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Improved consistency regarding quality of service is needed throughout the communications industry, especially in IP-related areas within and outside the ITU. + +This Recommendation provides a practical "top-down" path from a general quality definition (ISO 8402) to a QoS definition (ITU-T Rec. E.800) to network performance (ITU-T Rec. I.350, and Y.1540) to a functional breakdown of all components of service quality (the QoS definition matrix of ETSI ETR 003). Additionally presented are four viewpoints of QoS that make the definitions and framework meaningful for everyone: users, vendors, network operators, service providers, etc. + +This overall approach is believed to be highly useful because it encourages a consistent and uniform mapping between the top-down, framework definitions of QoS and the bottom-up, operational measures on network elements. Advantages of using this approach is that it not only helps identify QoS-related problems, but it also facilitates quantifying the problem from multiple views; the customer's (e.g. surveys and subjective tests) and the service provider's (network measurements). This helps assure that resolving the problem in one domain (e.g. the provider) also resolves it in the other (e.g. the customer). + +### **Source** + +ITU-T Recommendation G.1000 was prepared by ITU-T Study Group 12 (2001-2004) and approved under the WTSA Resolution 1 procedure on 29 November 2001. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +### NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2002 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +| | Page | +|---------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 1 | +| 4 Abbreviations and Acronyms ..... | 2 | +| 5 Communications Quality of Service: A framework and approach..... | 2 | +| 5.1 An elaboration on definitions for Quality and Quality of Service..... | 2 | +| 5.2 A framework for the quality of communications services..... | 2 | +| 5.3 Matrix for the determination of communications QoS criteria..... | 3 | +| 5.4 Relationship between QoS and Network performance..... | 4 | +| 5.5 Four viewpoints of QoS..... | 4 | +| 5.5.1 Customer's requirements of QoS ..... | 5 | +| 5.5.2 QoS offered by the service provider..... | 5 | +| 5.5.3 QoS achieved or delivered by the service provider..... | 5 | +| 5.5.4 QoS perceived by the customer ..... | 5 | +| 5.6 Relationship between the four viewpoints of QoS ..... | 6 | +| 5.7 The Challenge of IP-related QoS..... | 6 | +| 6 Conclusion ..... | 6 | +| Appendix I – Bibliography ..... | 7 | + + + +# Communications quality of service: A framework and definitions + +## 1 Scope + +This Recommendation addresses the need for a consistent approach to QoS, with a goal of setting a well-defined and relevant (e.g. customer-affecting) approach that can be readily used to plan and deploy networks, and to monitor service quality. Improved consistency regarding QoS is needed throughout the communications industry, especially in IP-related areas. + +While there is an urgent need in the industry for more consistency and uniformity in QoS as it applies to IP-related networks and services, the QoS framework and approach presented here can be applied to all communications services, such as mobile, wireline, multimedia, etc. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions, which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is published regularly. + +NOTE – The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- ETSI ETR 003 ed.2 (1994), *Network Aspects (NA); General Aspects of Quality of Service (QoS) and Network Performance (NP)*. +- ISO 8402:1994, *Quality management and quality assurance – Vocabulary*. +- ISO 9000:2000, *Quality management systems – Fundamentals and vocabulary*. +- ITU-T Recommendation E.800 (1994), *Terms and definitions related to quality of service and network performance including dependability*. +- ITU-T Recommendation G.1010 (2001), *End-user multimedia QoS categories*. +- ITU-T Recommendation I.350 (1993), *General aspects of quality of service and network performance in digital networks, including ISDN*. +- ITU-T Recommendation Y.1540 (1999), *Internet protocol data communication service – IP packet transfer and availability performance parameters*. + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 quality:** the totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs (ISO 8402). + +**3.2 quality of service (QoS):** the collective effect of service performances, which determine the degree of satisfaction of a user of the service (ITU-T Rec. E.800). + +**3.3 QoS requirements of user/customer:** a statement of the level of quality *required* by the applications of customers/users of a service, which may be expressed non-technically. + +**3.4 QoS offered/planned by provider:** a statement of the level of quality *expected* to be offered to the customer by the service provider. + +**3.5 QoS delivered/achieved by provider:** a statement of the level of the *actual* quality achieved and delivered to the customer. + +**3.6 QoS perceived by user/customer:** is a statement expressing the level of quality that customers *believe* they have experienced. + +## **4 Abbreviations and Acronyms** + +This Recommendation uses the following abbreviations: + +ETSI European Telecommunications Standards Institute + +FITCE Federation of Telecommunications Engineers of the European Community (*Fédération des ingénieurs et experts des télécommunications de la Communauté Européenne*) + +IETF Internet Engineering Task Force + +IP Internet Protocol + +ISO International Organization for Standardization + +ITU-T International Telecommunication Union – Telecommunication Standardization Sector + +NI Network Interface + +NP Network Performance + +QoS Quality of Service + +SLA Service Level Agreement + +# **5 Communications Quality of Service: A framework and approach** + +## **5.1 An elaboration on definitions for Quality and Quality of Service** + +The term *quality of service* (QoS) is extensively used today, not just in the telecommunications world in which it has its roots, but increasingly regarding broadband, wireless and multimedia services that are IP-based. Networks and systems are gradually being designed in consideration of end-to-end performance required by user applications; however, the term QoS is usually not well-defined, is used loosely, or worst of all, misused. + +In looking for candidate definitions of quality and QoS, ISO 8402 provides a general definition of quality itself, whereas ITU-T Rec. E.800 provides a definition of QoS: + +As noted, a definition of general quality is provided in ISO 8402 as "*the totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs.*" Similarly, ISO 9000 defines quality as the "*degree to which a set of inherent characteristics fulfills requirements.*" The ISO 8402 definition seems better from the user's view. In any event, QoS is clearly a subset of overall quality. + +As noted, ITU-T Rec. E.800 defines QoS as "*the collective effect of service performance which determine the degree of satisfaction of a user of the service.*" + +Most publications, including many standards, use the term QoS but either do not define it, or else point to one of these other few definitions. For example, in many industry standards, reports and specifications, QoS is not clearly defined, or else reference is made to ITU-T Rec. E.800. + +## **5.2 A framework for the quality of communications services** + +The framework described in ITU-T Rec. E.800 highlights some operational aspects of providing networks and services, but suffers from not being very application-oriented, and, in many areas, too + +vague to use. So while the definition of QoS in ITU-T Rec. E.800 is fairly widely used, the E.800 framework is not. + +Even if one adopts ISO 8402 as a definition of quality, and ITU-T Rec. E.800 as a definition of QoS, some way is still needed of relating the application-affecting functions of a service to the various criteria used to assess the quality with which these functions are performed. A telecommunications services quality framework [I.1] was adopted by the Federation of Telecommunications Engineers of the European Community (FITCE), with an extremely thorough assessment of how it could be used in practice. ETR 003 from ETSI provides a readily available source for this same framework and QoS approach, which is elaborated below. + +## 5.3 Matrix for the determination of communications QoS criteria + +Quality criteria of a telecommunications service may be derived from a matrix shown in Figure 1. Considerable thought has gone into its construction and has proven to be useful in identifying QoS criteria for customers before launching a new service (see ETSI ETR 003). The FITCE Study Commission found that, depending upon the granularity of QoS required for a service, as many as 43 QoS criteria may be deduced, and as few as 13 important ones for basic telephony service. + +| | | Service Quality Criteria | | | | | | | +|-------------------------------------------|-----------------------------------|--------------------------|---------------|-------------------|------------------|---------------|-----------------|------------------| +| | | SPEED
1 | ACCURACY
2 | AVAILABILITY
3 | RELIABILITY
4 | SECURITY
5 | SIMPLICITY
6 | FLEXIBILITY
7 | +| Service Function | | | | | | | | | +| SERVICE
MANAGEMENT | Sales & Pre-Contract Activities 1 | | | | | | | | +| | Provision 2 | | | | | | | | +| | Alteration 3 | | | | | | | | +| | Service Support 4 | | | | | | | | +| | Repair 5 | | | | | | | | +| | Cessation 6 | | | | | | | | +| CONNECTION
QUALITY | Connection Establish. 7 | | | | | | | | +| | Information Transfer 8 | | | | | | | | +| | Connection Release 9 | | | | | | | | +| Billing 10 | | | | | | | | | +| Network/Service management by customer 11 | | | | | | | | | + +**Figure 1/G.1000 – Matrix to facilitate identification of communications QoS criteria** + +This matrix may be used for any telecommunications service to determine the requisite QoS criteria. After determining the quality criteria, parameters can be defined and performance objectives set. + +## 5.4 Relationship between QoS and Network performance + +Network performance contributes towards QoS as experienced by the user/customer. Network performance may or may not be on an end to end basis. For example, access performance is usually separated from the core network performance in the operations of single IP network, while Internet performance often reflects the combined NP of several autonomous networks + +Other ITU-T Rec., such as I.350 and Y.1540, have gone on to develop far more detail for network performance and the NI-to-NI part of overall QoS, in addition to contrasting QoS and network performance. But ITU-T Rec. E.800 remains the most meaningful ITU-T definition from the user's perspective, even though, as mentioned, the framework of ITU-T Rec. E.800 is vague in areas and has thus led to a variety of interpretations. So while the framework of ITU-T Rec. E.800 needs to be more concrete and more application-oriented, its basic definition of QoS is good. + +## 5.5 Four viewpoints of QoS + +The QoS definition matrix of Figure 1 gives criteria for judging the quality of the communications functions that any service must support. However, even this definitional matrix can be viewed from different perspectives: + +- Customer's QoS requirements; +- Service provider's offerings of QoS (or planned/targeted QoS); +- QoS achieved or delivered; +- Customer survey ratings of QoS. + +For any framework of QoS to be truly useful and practical enough to be used across the industry, it must be meaningful from these four viewpoints, which are illustrated in Figure 2 and defined thereafter. While Figure 2 shows the "top down" relationship of these viewpoints, it does not indicate how, for example, QoS actually gets implemented by the service provider. This requires many detailed methods done in a more "bottom up" operation that is not addressed in this Recommendation. (The point of this Recommendation is that a single QoS definition and framework can support all of the viewpoints of Figure 2.) + +![Diagram illustrating the four viewpoints of QoS, showing the relationship between Customer and Service Provider perspectives.](c2fc2621e8206d24427b56bcb2398fc0_img.jpg) + +The diagram is titled "Figure 2/G.1000 – The four viewpoints of QoS". It is divided into two vertical panels by a dashed line. The left panel is labeled "CUSTOMER" and the right panel is labeled "SERVICE PROVIDER". + +In the CUSTOMER panel, there are two boxes: "Customer's QoS Requirements" at the top and "QoS Perceived By Customer" at the bottom. A blue arrow points from the bottom box to the top box. + +In the SERVICE PROVIDER panel, there are two boxes: "QoS Offered By Provider" at the top and "QoS Achieved by Provider" at the bottom. A blue arrow points from the top box to the bottom box. + +Horizontal blue arrows connect the panels: one from "Customer's QoS Requirements" to "QoS Offered By Provider", and another from "QoS Achieved by Provider" to "QoS Perceived By Customer". + +A small text label "T1213040-02" is located at the bottom right of the diagram. + +Diagram illustrating the four viewpoints of QoS, showing the relationship between Customer and Service Provider perspectives. + +Figure 2/G.1000 – The four viewpoints of QoS + +### **5.5.1 Customer's requirements of QoS** + +QoS requirements by the customer state the level of quality required of a particular service, which may be expressed in non-technical language. The customer is not concerned with how a particular service is provided, or with any aspects of the network's internal design, but only with the resulting end-to-end service quality. From the customer's point of view, quality of service is expressed by parameters, which: + +- focus on user-perceived effects, rather than their causes within the network; +- do not depend, in their definition, on assumptions about the internal design of the network; +- take into account all aspects of the service from the customer's point of view; +- may be assured to a user by the service providers, sometimes in contractual terms; +- are described in network-independent terms and create a common language understandable by both the user and the service provider. + +Of special interest is ITU-T Rec. G.1010 on the QoS requirements of end users for all their applications. This Recommendation explicitly addresses the "customer requirement" viewpoint, which can be used by the service provider to plan the network service level. + +### **5.5.2 QoS offered by the service provider** + +QoS offered by the service provider is a statement of the level of quality expected to be offered to the customer by the service provider. The level of quality is expressed by values assigned to QoS parameters. The principal use of this form of QoS is for planning and for Service Level Agreements. Each service would have its own set of QoS parameters (as in the QoS Classes of ITU-T Rec. Y.1540 for IP service offers). The service provider may express the offered QoS in non-technical terms for the benefit of customers, and in technical terms for use within the business. + +QoS offered by the service provider can be used in planning documents, to specify measurement systems and also can be used to form the basis of the SLAs. + +For example, a service provider may state, for the benefit of customers, that the availability of basic telephony service is planned to be 99.95% in a year with not more than a 15-minute break at any one occasion, and not more than 3 breaks over the year. + +#### **5.5.3 QoS achieved or delivered by the service provider** + +QoS achieved by the service provider is a statement of the level of quality actually achieved and delivered to the customer. This is expressed by values assigned to parameters, which should be the same as specified for the offered QoS so that the two can be compared to determine what was actually achieved to assess the level of performance achieved. These performance figures are summarised for specified periods of time, e.g. for the previous month. + +For example, the service provider may state that the achieved availability for the previous quarter was 99.95% with five breaks of service of which one lasted 65 minutes. The QoS achieved or delivered is used by the industry, sometimes by regulators, for publication in the interests of customers. + +#### **5.5.4 QoS perceived by the customer** + +QoS perceived by the users or customers is a statement expressing the level of quality experienced they 'believe' they have experienced. The Perceived QoS is expressed, usually in terms of degrees of satisfaction and not in technical terms. Perceived QoS is assessed by customer surveys and from customer's own comments on levels of service. Perceived QoS can be used by the service provider to determine customer satisfaction of the service quality. For example, a customer may state that on an unacceptable number of occasions, there was difficulty in getting through the network to make a call and may give it a rating of 2 on a 5-point scale: 5 indicating excellent service. Ideally there would be 1:1 correspondence between delivered and perceived QoS. + +## 5.6 Relationship between the four viewpoints of QoS + +The customer's QoS requirements (such as those given in ITU-T Rec. G.1010) may be considered as the logical starting point. A set of customer's QoS requirements may be treated in isolation as far as its capture is concerned. This requirement is an input to the service provider for the determination of the QoS to be offered or planned. The service provider may not always be in a position to offer customers the level of QoS they require. Considerations such as cost of quality, strategic aspects of the service providers' business, benchmarking ("best in class") and other factors will influence the level of quality offered. The customer's requirements may also influence what monitoring systems are to be instituted for the determination of achieved QoS for the purpose of regular reports on achieved quality. The combination of relationships forms the basis of a practical and effective management of service quality; one measure of progress could be considered to be when the four views of QoS begin to converge for a given service. + +## 5.7 The Challenge of IP-related QoS + +There are many issues presented by the use of IP-based networks and services, such as the lack of proven, robust and scalable standard mechanisms for: + +- dynamic allocations of resources (like packet loss and delay) among network segments; +- assuring that required end-to-end network performance objectives are in fact achieved; +- seamless signaling of desired end-to-end QoS across both network and peer interfaces; +- performance monitoring of IP-based networks and services that are consistent with methods used for network and service planning, and also meaningful to the user experience; and +- rapid and complete restoration of IP layer connectivity following severe outages (or attacks) of heavily loaded networks. + +If such issues are to be addressed in a timely fashion, a consistent QoS approach is clearly helpful. + +## 6 Conclusion + +In summary, this Recommendation provides a practical "top-down" path from a general quality definition (ISO 8402) to a QoS definition (ITU-T Rec. E.800) to network performance (ITU-T Rec. I.350 and Y.1540) to a functional breakdown of all components of service quality (the QoS definition matrix of ETSI ETR 003). Additionally presented are four viewpoints of QoS that make the definitions and framework meaningful for everyone: users, vendors, network operators, service providers, etc. + +This overall approach is believed to be highly useful because it encourages a consistent and uniform mapping between the top-down, framework definitions of QoS and the bottom-up, operational measures on network elements. Advantages of using this approach are that it not only helps identify QoS-related problems, but it also facilitates quantifying the problem from multiple viewpoints: the customer's (e.g. surveys and subjective tests) and the service provider's (network measurements). This helps assure that resolving the problem in one domain (e.g. the provider) also resolves it in the other (e.g. the customer). + +## APPENDIX I + +### **Bibliography** + +- [I.1] RICHTERS (J.S.), DVORAK (C.A.): A Framework for Defining the Quality of Communications Services, *IEEE Communications Magazine*, Volume 26, Issue 10, pp. 17-23, October 1988. + + + + + +### SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | 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b/marked/G/T-REC-G.1020-200607-I_PDF-E/raw.md @@ -0,0 +1,1088 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.1020** + +(07/2006) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Quality of service and performance – Generic and user-related aspects + +--- + +**Performance parameter definitions for quality of +speech and other voiceband applications +utilizing IP networks** + +ITU-T Recommendation G.1020 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Performance parameter definitions for quality of speech and other voiceband applications utilizing IP networks + +## Summary + +The transmission of speech and other voiceband applications over packet networks brings with it new, sometimes unique, forms of quality degradation. There are many existing definitions for packet network performance parameters, yet the desire to control the quality of non-elastic isochronous applications requires additional, complementary information. The purpose of this Recommendation is to define packet network and terminal performance parameters that better reflect the perceived quality of the target applications. It is largely focused on quality impairments resulting from delay variation and packet loss which are peculiar to IP and other packet-based technologies, and which do not appear in traditional TDM networks. It discusses the interactions and trade-offs among these packet impairments, and describes mechanisms such as de-jitter buffers and packet loss concealment for reducing their effects on the quality of speech and other applications. However, this Recommendation avoids overlap by making reference to existing definitions wherever possible. + +The parameters defined by this Recommendation extend beyond the IP layer in many cases. End-to-end packet system (combination of end terminals and network) parameters are also necessary to determine the speech/voiceband quality. Clauses 5, 6 and 7 collect the parameter definitions for source terminals, packet networks, and destination terminals, respectively. Overall parameters are defined in clause 8. + +In this version, the Recommendation adds formal definitions for many of the voice metrics identified in RFC 3611, RTCP Extended Reports (RTCP-XR). + +Annex A defines the gateway-specific reference points and parameters. Annex B provides information on packet loss distributions and packet loss models, and defines burst packet loss parameters. Annex C specifies an adaptive de-jitter buffer emulator and defines de-jitter buffer parameters. Appendix I tabulates the RTCP-XR parameters, along with the examination existing Recommendations and the final action, which typically was the addition of a parameter in this Recommendation. + +## Source + +ITU-T Recommendation G.1020 was approved on 14 July 2006 by ITU-T Study Group 12 (2005-2008) under the ITU-T Recommendation A.8 procedure. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2007 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +| | | Page | +|---------|---------------------------------------------------------------------------|------| +| 1 | Scope ..... | 1 | +| 2 | References..... | 3 | +| 3 | Definitions ..... | 3 | +| 4 | Abbreviations..... | 4 | +| 5 | Source terminal packet parameters..... | 5 | +| 5.1 | Analogue/digital conversion clock accuracy (free-running) ..... | 5 | +| 5.2 | Packet information field size ..... | 6 | +| 5.3 | Packet overhead..... | 6 | +| 5.4 | Source terminal delay ..... | 6 | +| 5.5 | Source terminal delay variation..... | 6 | +| 6 | Packet network performance parameters..... | 7 | +| 6.1 | Summary of network performance parameters ..... | 7 | +| 6.2 | Additional network parameters recommended..... | 8 | +| 7 | Destination terminal packet parameters..... | 9 | +| 7.1 | Discussion of destination packet processing..... | 10 | +| 7.2 | Taxonomy of de-jitter buffer types/parameters and models..... | 11 | +| 7.3 | System frequency offset, using destination clock as reference ..... | 15 | +| 7.4 | Packet loss concealment (type, delay)..... | 15 | +| 8 | Overall performance parameters..... | 16 | +| 8.1 | Overall delay (including source, network and destination)..... | 16 | +| 8.2 | End System Delay ..... | 16 | +| 8.3 | Round Trip Delay ..... | 16 | +| 8.4 | Time-scale discontinuities in post-de-jitter and PLC stream ..... | 16 | +| 8.5 | Overall (frame/packet) loss (including network and destination) ..... | 17 | +| Annex A | – VoIP gateway-specific reference points and performance parameters ..... | 18 | +| A.1 | Introduction ..... | 18 | +| A.2 | Definitions ..... | 18 | +| A.3 | Source gateway parameters ..... | 18 | +| A.4 | Destination gateway parameters..... | 19 | +| A.5 | Overall delay ..... | 20 | +| Annex B | – Packet loss distributions and packet loss models ..... | 20 | +| B.1 | Introduction ..... | 20 | +| B.2 | Common packet loss models ..... | 20 | +| B.3 | Example packet trace..... | 23 | +| B.4 | Bibliography to Annex B..... | 24 | + +| | Page | +|------------------------------------------------------------|-------------| +| Annex C – Example adaptive de-jitter buffer emulator ..... | 26 | +| C.1    Introduction ..... | 26 | +| C.2    Parameter definitions ..... | 26 | +| C.3    De-jitter buffer emulation ..... | 27 | +| Appendix I – List of RTCP XR metrics..... | 28 | +| BIBLIOGRAPHY ..... | 29 | + +# Introduction + +The transmission of speech and other voiceband applications over packet networks brings with it new, sometimes unique, forms of quality degradation. There are many existing definitions for packet network performance parameters, yet the desire to control the quality of non-elastic isochronous applications requires additional, complementary information. The purpose of this Recommendation is to define packet network and terminal performance parameters that better reflect the perceived quality of the target applications, extending beyond the IP layer in many cases. End-to-end packet system (combination of end terminals and network) parameters are also necessary to determine the speech/voiceband quality, and this Recommendation defines them as well. + + + +# **Performance parameter definitions for quality of speech and other voiceband applications utilizing IP networks** + +# **1 Scope** + +This Recommendation defines a set of performance parameters for packet networks and end terminals that can assist in quantifying the end-to-end quality of speech and other voiceband applications. It is largely focused on quality impairments resulting from delay variation and packet loss which are peculiar to IP and other packet-based technologies, and which do not appear in traditional TDM networks. It discusses the interactions and trade-offs among these packet impairments, and describes mechanisms such as de-jitter buffers and packet loss concealment for reducing their effects on the quality of speech and other applications. + +This Recommendation recognizes existing performance parameter definitions, and avoids duplication. Many factors that determine the quality of speech and voiceband applications are common to both TDM and IP-based networks, and are addressed in existing Recommendations. In the parlance of ITU-T Rec. I.350, the scope of this Recommendation is limited to the information transfer function of the $3 \times 3$ matrix, and only to the bearer channel. Call processing aspects of connection access and disengagement (e.g., dialtone delay and post-dialling delay) are not considered in this Recommendation. Furthermore, this Recommendation does not specify numerical objectives for packet networks or end terminals, although this will be the subject of follow-on work. + +Figure 1 illustrates this scope, along with some other specifications with their areas of coverage. This Recommendation only defines parameters that describe packet terminal and packet transmission impairments that are unique to speech and voiceband application quality assessment. + +![Diagram illustrating the scope of ITU-T Rec. G.1020 as it relates to other performance specifications. The diagram shows two communication stacks connected via IP Networks. The left stack includes Mic A/D coder, Form packets, RTP, UDP, IP, and Lower layers, connected to a LAN/End terminal via a UNI. The right stack includes Spkr D/A coder, De-pkt De-jitter, RTP, UDP, IP, and Lower layers, also connected to a LAN/End terminal via a UNI. A central 'Call processing (Y.1530)' block is shown between the UNIs. A large blue box labeled 'Scope of G.1020' encompasses the top layers of both stacks. Arrows indicate relationships to other specifications: 'Parameter definitions' point to the top layers, 'Y.1540' points to the IP layer, and 'Numeric objectives' point to the end-to-end path (LAN/End terminal to IP Networks Y.1541 to LAN/End terminal), with a specific reference to 'G.114'.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Diagram illustrating the scope of ITU-T Rec. G.1020 as it relates to other performance specifications. The diagram shows two communication stacks connected via IP Networks. The left stack includes Mic A/D coder, Form packets, RTP, UDP, IP, and Lower layers, connected to a LAN/End terminal via a UNI. The right stack includes Spkr D/A coder, De-pkt De-jitter, RTP, UDP, IP, and Lower layers, also connected to a LAN/End terminal via a UNI. A central 'Call processing (Y.1530)' block is shown between the UNIs. A large blue box labeled 'Scope of G.1020' encompasses the top layers of both stacks. Arrows indicate relationships to other specifications: 'Parameter definitions' point to the top layers, 'Y.1540' points to the IP layer, and 'Numeric objectives' point to the end-to-end path (LAN/End terminal to IP Networks Y.1541 to LAN/End terminal), with a specific reference to 'G.114'. + +**Figure 1/G.1020 – Scope of ITU-T Rec. G.1020 as it relates to other performance specifications** + +Note that the number of IP networks between terminals is not limited in these definitions. + +Other ITU-T Recommendations supplement the parameters provided in this Recommendation. For example, transmission planning over hybrid Internet/PSTN connections is covered in ITU-T Rec. G.177. Still, other Recommendations specify such parameters in the context of assessing the performance of IP packet transfer on international data communication services (e.g., ITU-T Rec. Y.1540). Network performance objectives for different QoS classes of IP-based services are described in ITU-T Rec. Y.1541, and end-to-end one-way delay objectives are specified in ITU-T Rec. G.114. + +New Recommendations that complement ITU-T Rec. G.1020 are anticipated. Call processing aspects of the connection are in development. The ITU-T is also currently working on new Recommendations dealing with situations where the network is mainly an IP network with islands of PSTN, and where the network is mainly a PSTN network with islands of IP. ITU-T work to specify the performance objectives for VoIP terminals and gateways was recently completed in ITU-T Rec. P.1010. Finally, there is work on methods to assess the performance by measuring metrics related to the end-to-end quality of VoIP. + +The definitions of packet transmission parameters that are unique to ATM networks are explicitly out of the scope of this Recommendation. + +This Recommendation should be particularly useful to those new to the area of Voice over IP (VoIP) who want to gain a better understanding of the factors affecting the quality of these telecommunication systems. Developers of telecommunication equipment can use the parameters defined in this Recommendation to specify relevant aspects of their contribution to end-to-end performance. Service providers can use these parameters to effectively summarize performance of IP network solutions. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- ITU-T Recommendation G.107 (2005), *The E-model, a computational model for use in transmission planning*. +- ITU-T Recommendation G.113 (2001), *Transmission impairments due to speech processing*. +- ITU-T Recommendation G.114 (2003), *One-way transmission time*. +- ITU-T Recommendation G.177 (1999), *Transmission planning for voiceband services over hybrid Internet/PSTN connections*. +- ITU-T Recommendation I.356 (2000), *B-ISDN ATM layer cell transfer performance*. +- ITU-T Recommendation P.51 (1996), *Artificial mouth*. +- ITU-T Recommendation P.57 (2005), *Artificial ears*. +- ITU-T Recommendation P.1010 (2004), *Fundamental voice transmission objectives for VoIP terminals and gateways*. +- ITU-T Recommendation Y.1540 (2002), *Internet protocol data communication service – IP packet transfer and availability performance parameters*. +- ITU-T Recommendation Y.1541 (2006), *Network performance objectives for IP-based services*. +- IETF RFC 3611 (2003), *RTP Control Protocol Extended Reports (RTCP XR)*. + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 ear reference point:** A virtual point for geometric reference located at the entrance to the listener's ear, traditionally used for calculating telephonometric loudness ratings [P.57]. + +**3.2 terminal input measurement point:** A measurement point in the physical medium connecting a terminal to an IP network that is crossed as IP packets leave the IP network and enter the terminal. This measurement point is as close to the terminal as possible. + +**3.3 IP terminal:** An endpoint device intended for connecting to an IP network to support speech communications. These devices can be dedicated (e.g., a telephone set) or general purpose (e.g., a computer running an application that performs the terminal function). + +**3.4 terminal output reference point:** A measurement point in the physical medium connecting a terminal to an IP network that is crossed as IP packets leave the terminal and enter the IP network. This measurement point is as close to the terminal as possible. + +**3.5 de-jitter buffer:** A buffer designed to remove the delay variation (i.e., jitter) in packet arrival times. Data is put into the de-jitter buffer at a variable rate (i.e., whenever they are received from the network), and taken out at a constant rate. + +**3.6 mouth reference point:** The point on the reference axis, 25 mm in front of the lip plane [P.51]. + +**3.7 real-time signal:** A signal accurately representing acoustic or electrical signals in the time domain. + +**3.8 receive electrical reference point:** An electrical point of reference that is equivalent to the ear reference point from a terminal delay measurement perspective. + +**3.9 send electrical reference point:** An electrical point of reference that is equivalent to the mouth reference point from a terminal delay measurement perspective. + +# **4 Abbreviations** + +This Recommendation uses the following abbreviations: + +| | | +|---------|-----------------------------------------------------| +| ADC | Analogue-to-Digital Converter | +| ATM | Asynchronous Transfer Mode | +| DAC | Digital-to-Analogue Converter | +| DSCP | Differentiated Services Code Point | +| Dst | Destination | +| HDLC | High-level Data Link Control | +| IETF | Internet Engineering Task Force | +| IP | Internet Protocol | +| IPER | IP Packet Error Ratio | +| IPErr | Errored IP Packet Count | +| IPLR | IP Packet Loss Ratio | +| IPPM | IP Performance Metrics working group | +| IPRE | IP packet transfer Reference Event | +| IPSLB | IP Packet Severe Loss Block | +| IPSLBR | IP Packet Severe Loss Block Ratio | +| IPTD | IP Packet Transfer Delay | +| IPv4 | Internet Protocol version 4 | +| IPv6 | Internet Protocol version 6 | +| MAPDV2 | Mean Absolute Packet Delay Variation 2 | +| NA | Not Available | +| PSTN | Public Switched Telephone Network | +| QoS | Quality of Service | +| RFC | Request For Comments | +| RSVP-TE | Resource Reservation Protocol – Traffic Engineering | +| RTCP | Real-time Transport Control Protocol | +| RTP | Real-time Transport Protocol | +| RTPErr | Errored RTP Packet Count | +| SPR | Spurious Packet Ratio | +| Src | Source | + +| | | +|--------|--------------------------| +| TDM | Time Division Multiplex | +| UDP | User Datagram Protocol | +| UDPErr | Errored UDP Packet Count | +| UNI | User-Network Interface | + +# 5 Source terminal packet parameters + +This clause gives the relevant sending terminal packet parameters that have a direct effect on perceived speech and voiceband application quality. Figure 2 indicates the positions of measurement points and system components. + +![Figure 2/G.1020 – Source terminal diagram and reference points. The diagram shows the signal flow from a microphone to a terminal output reference point. The signal starts at the 'Mouth reference point' and 'Send electrical reference point', passing through a 'Mic' to an 'A/D converter'. The A/D converter is connected to a clock source (indicated by a circle with a sine wave symbol). The output of the A/D converter is a 'Continuous digital' signal (dashed blue line) that passes through 'Source encoding', 'Channel encoding', and 'Packetization'. The output of 'Packetization' is an 'Asynchronous packets' signal (dotted red line) that passes through 'RTP/UDP', 'IP', 'Lower layers', and 'Physical interface'. The signal then reaches the 'Terminal output reference point'. A legend at the bottom left indicates: 'Waveform' (solid green line), 'Continuous digital' (dashed blue line), and 'Asynchronous packets' (dotted red line). The diagram is labeled 'G.1020(06)_F02'.](ff0952ef692c9d960ce5f6708bcc9711_img.jpg) + +Figure 2/G.1020 – Source terminal diagram and reference points. The diagram shows the signal flow from a microphone to a terminal output reference point. The signal starts at the 'Mouth reference point' and 'Send electrical reference point', passing through a 'Mic' to an 'A/D converter'. The A/D converter is connected to a clock source (indicated by a circle with a sine wave symbol). The output of the A/D converter is a 'Continuous digital' signal (dashed blue line) that passes through 'Source encoding', 'Channel encoding', and 'Packetization'. The output of 'Packetization' is an 'Asynchronous packets' signal (dotted red line) that passes through 'RTP/UDP', 'IP', 'Lower layers', and 'Physical interface'. The signal then reaches the 'Terminal output reference point'. A legend at the bottom left indicates: 'Waveform' (solid green line), 'Continuous digital' (dashed blue line), and 'Asynchronous packets' (dotted red line). The diagram is labeled 'G.1020(06)\_F02'. + +Figure 2/G.1020 – Source terminal diagram and reference points + +## 5.1 Analogue/digital conversion clock accuracy (free-running) + +The relative frequency offset of a clock may be specified as: + +$$\frac{\Delta f}{f_{\text{nominal}}} = \frac{f_{\text{measured}} - f_{\text{nominal}}}{f_{\text{nominal}}}$$ + +The measured frequency error should be minimized, and use of an atomic frequency reference for measurement is preferred (the nominal frequency should be as close to ideal as practical). + +The long-term (or end-of-life) accuracy of the clock oscillator technology (e.g., quartz crystal) may also be given if known, as it establishes an upper bound on the frequency offset. + +For example, assume that the nominal frequency of the analogue/digital conversion oscillator is 8000 Hz. A measurement on the source terminal oscillator indicates a frequency of 8000.0027 Hz. The relative frequency offset is then $0.0027/8000 = 3.38 \times 10^{-7}$ . Disciplined quartz oscillators can usually achieve offsets of $1 \times 10^{-6}$ based on their accuracy specifications. + +Note that it should be possible to infer the sending clock frequency from measurements of the source packet rate (under favourable circumstances, for example, when silence suppression is disabled). This would permit a measurement using externally available signals. The method is for further study. + +Relative frequency offset is a unit-less quantity, often specified as a fraction or in parts per million. + +## 5.2 Packet information field size + +The Packet information field size specifies the amount of encoded voiceband waveform that a packet contains. This size must be expressed unambiguously, using as many of the following units of measure as necessary: + +- 1) The number of 8-bit octets of encoded voiceband signals and supporting information (e.g., bits associated with forward error correction to aid packet loss concealment, or bits associated with encryption). +- 2) The number of encoder frames (the specific encoder and native frame size must also be specified). +- 3) The amount of continuous waveform time represented by the encoded bits in the field. + +Typical information fields contain one or two encoder frames and combine 10 or 20 ms of waveform time in a single packet. Annex A/G.114 provides guidance on the calculation of delay for various coders and packet information field sizes. + +## 5.3 Packet overhead + +The total octets appended to the packet information field should be counted separately for each protocol layer header. The total octets dedicated to non-information headers may be counted as the packet exits the terminal output reference point, therefore, including the effects of header compression, if any. The octet size of packets dedicated to media flow control, status/performance reports (e.g., RTCP), or other non-media carrying packets should be counted separately. Some typical overhead contributors are (in octets): + +RTP:12; UDP:8; IPv4:20; IPv6:40; HDLC Encapsulation:8; Flag:1. + +The unit of measure for packet overhead is 8-bit octets. + +## 5.4 Source terminal delay + +The source terminal delay is the interval defined by the time that a signal enters the mouth reference point and the time that the first bit of the corresponding encoded, packetized signal exits the terminal output reference point. When appropriate, the send electrical reference point may be substituted for the mouth reference point. By definition, the source terminal delay includes the entire packetization/depacketization time, and test waveforms and methods must retain sufficient information to assess packetization time variability due to alignment between the test signal and the packet boundaries. For example, the test signal must be of sufficient length to span packet boundaries, permitting boundary identification in time. The portion of the signal that is carried by the earliest part of the packet payload should be used. + +NOTE – This delay will include source terminal delay variation if present, and appropriate statistics should be applied to summarize the variation. + +The unit of measure for source terminal delay is time in seconds. + +## 5.5 Source terminal delay variation + +The fundamental notion of a 1-point delay variation parameter is the comparison between the actual packet emission pattern and the intended (usually periodic) emission pattern. Some variations of this definition include a "skipping clock" adjustment, as in ITU-T Rec. I.356. + +The source terminal delay variation is defined as the time difference between the first bit of a packet emission at the terminal output reference point and the ideal periodic reference time. For the first packet in a flow, the ideal periodic reference time is set equal to the emission time. Subsequent packets emissions are compared to this periodic time reference, as shown below: + +$$\text{Source Terminal Delay Variation} = t(\text{packet\_n}) - t(\text{reference\_packet\_n})$$ + +where $t(\text{reference\_packet\_n})$ is the emission time of $\text{packet\_n}$ of the ideal periodic reference stream. The time interval of measurement, along with appropriate statistics, should be provided. + +NOTE – Long interval measurements may include the undesired effects of source frequency offset. Variation due to source frequency offset should be noted and removed as a measurement error, when possible. + +The unit of measure for source terminal delay variation is seconds. + +# 6 Packet network performance parameters + +Standards for IP layer packet transfer performance (see e.g., ITU-T Recs Y.1540, Y.1541 and IETF RFCs 2330, 2678 through 2681, 3357 and 3393) include the following parameters: One-way transfer delay, delay variation, and packet loss. These parameters must be mapped to the application layer to adequately estimate user impact. + +## 6.1 Summary of network performance parameters + +Table 1 summarizes the IP network performance parameters relevant to this Recommendation, and the relationships among network and terminal parameters that form the basis for overall system parameters. Reading left to right, each row identifies a parameter and indicates how it may be combined with other parameters to derive a specific overall performance parameter for one aspect of the end-to-end or user-user quality (although the exact formulas are given in later clauses). + +**Table 1/G.1020 – Summary of IP network performance parameters and mapping to overall/user-user parameters** + +| IP network parameter (Note) | Translation to overall | Overall parameter | +|----------------------------------------------------------|-------------------------------------------------------------------------------------------|---------------------------------------------------| +| Transfer delay (IPTD, mean) | IPTD + Src delay + Dst delay | Mean user-user delay | +| Delay variation (IPDV, 99.9%tile minus the minimum) | Combine with Src delay variation distribution | Contributes to Dst delay, or audio frame loss | +| Delay jump (possibly captured by RFC 3393, for example) | May come from network path/facility change, or may only appear at de-jitter buffer output | Audio time-scale discontinuity | +| Errored packet (headers) | IPErr + UDPErr + RTPErr $\Rightarrow$ | Audio frame loss (packet or codec frame discard) | +| Reordered packet (Appendix VII/Y.1540) | (may be considered lost) $\Rightarrow$ | Audio frame loss | +| Lost packet | IP loss + (all audio defects) $\Rightarrow$ | Audio frame loss (pre-concealment) | +| IP severe loss block (IPSLB) | (depends on block duration) | Call cut-off | +| Loss patterns (e.g., RFC 3357) | Complete stream loss/arrival $\Rightarrow$ | Burst length/Consecutive loss | +| Packet rate (inferred from other system characteristics) | Difference of source and destination terminal ADC and DAC oscillators | System frequency offset (relative to destination) | +| NOTE – From ITU-T Rec. Y.1540, unless noted. | | | + +## 6.2 Additional network parameters recommended + +All the fundamental single packet outcomes are defined in ITU-T Rec. Y.1540 (and IETF RFCs listed in Bibliography). However, it is possible to derive additional parameters of interest when streams or flows of packets are considered, as in VoIP planning and measurement. + +### 6.2.1 Consecutive packet loss event + +For cases where successive packets, sent in a periodic stream (according to RFC 3432, for example), are designated as lost according to the definition of lost packet outcome in ITU-T Rec. Y.1540, then the length of the event should be specified as the number of packets lost in sequence. This length should be recorded separately for each event. Following a measurement encountering multiple consecutive loss events, the count for each event length should also be recorded. Sequence numbers contained in packet headers may assist this measurement. + +### 6.2.2 Degraded second + +A degraded second outcome occurs for a block of packets observed during a 1-second interval when the ratio of lost packets at the egress UNI to total packets in the corresponding second interval at the ingress UNI exceeds D%. Sequence numbers and timestamps contained in packet headers may be used to aid in this measurement. + +The value of D is provisionally set at 15%, and may change on the basis of further experience or study. For example, if a flow of packets at 50 packets per second is impaired by 8 losses (16%), then the quality will be degraded whether the losses are consecutive or distributed throughout the second. + +The unit of measure for the degraded second is a count of these outcomes. + +### 6.2.3 Short-term IP delay variation/jitter quantification + +The following clauses provide two approaches to short-term jitter quantification. When the distribution of delays over short intervals is available, then the first approach, based on short-term range is recommended. However, if the complete time series of delay variation is known, then the approach based on mean absolute packet delay variation may provide additional information. + +#### 6.2.3.1 Approach based on short-term range + +This definition is consistent with Appendix II/Y.1541. + +Short-term IP delay variation is defined as the maximum IPTD minus the minimum IPTD during a given short measurement interval. + +$$IPDV_{Short\_Term} = IPTD_{max} - IPTD_{min}$$ + +where: + +$IPTD_{max}$ is the maximum IPTD recorded during the short measurement interval; + +$IPTD_{min}$ is the minimum IPTD recorded during the short measurement interval. + +This is a simple and fairly accurate method for calculating IPDV in real-time. The length of the short measurement interval is for further study. The measurement interval influences the ability of the metric to capture low and high frequency variations in the IP packet delay behaviour. + +To be consistent with other parameter definitions in this Recommendation, a measurement interval of 1 second is provisionally agreed. + +Many values of $IPDV_{Short\_Term}$ are measured over a longer time interval (comprising many short measurement intervals). The 99.9th percentile of these $IPDV_{Short\_Term}$ values is expected to meet the Y.1541 objective of 50 ms (note that this objective was established for a 1-minute measurement interval and the percentile is evaluated on a per-packet basis, assuming a 50-packet per-second sending rate or higher). + +As an example, assume 1200 one-second measurements of $IPDV_{Short\_Term}$ , collected over 20 minutes. If two or more measurements of $IPDV_{Short\_Term}$ exceed 50 ms, then the Y.1541 objective may not have been met during a few intervals, and a more exact evaluation of the objective is warranted. + +The unit of measure for short-term range is seconds. + +#### 6.2.3.2 Approach based on mean absolute packet delay variation + +An alternative approach is to determine the mean absolute packet delay variation with regard to a short-term average or minimum value – termed here the *adjusted absolute packet delay variation*. This may provide a more meaningful relationship to de-jitter buffer behaviour. + +For packet 1: (or any packet arriving after 3 consecutive lost packets have been detected) + +$$D_1 = t_1$$ + +$$\text{Deviation } t_1 - D_1 = 0$$ + +should not be counted as Positive or Negative + +Do not compute MAPDV2 for the first packet. + +For subsequent packets: + +$$\text{mean delay } D_i = (15 \times D_{i-1} + t_{i-1})/16$$ + +if $t_i > D_i$ then + +$$\text{positive deviation } P_i = (7 \times P_{i-1} + t_i - D_i)/8$$ + +$$\text{negative deviation } N_i = (7 \times N_{i-1})/8$$ + +else (when $t_i \leq D_i$ ) + +$$\text{positive deviation } P_i = (7 \times P_{i-1})/8$$ + +$$\text{negative deviation } N_i = (7 \times N_{i-1} + D_i - t_i)/8$$ + +NOTE – For the first packet, $t_1, t_{i-1} = 0$ and $D_{i-1} = 0$ , so $t_1 = D_1$ , and deviations are not computed. + +We compute mean absolute packet delay variation 2 ( $MAPDV2$ ) for packet ( $i$ ) as: + +$$MAPDV2 = (P_i) + (N_i)$$ + +Note that the number of consecutive lost packets needed to reset the algorithm is based on an assumption that three lost packets will cause a typical de-jitter buffer to empty, and require priming as done at the beginning of a stream of packets. + +The unit of measure for $MAPDV2$ is seconds. + +# 7 Destination terminal packet parameters + +This clause gives the relevant destination terminal packet parameters that have a direct effect on perceived speech and voiceband application quality, and a set of overall packet parameters. Figure 3 indicates the positions of measurement points and system components. + +![Figure 3/G.1020 – Destination terminal components. This block diagram shows the signal flow from a terminal input reference point through various processing stages to an ear reference point. The top path consists of De-jitter buffer, De-packetize, Decoder & PLC, and D/A converter, connected by continuous digital signals (dashed blue arrows). The bottom path consists of Physical interface, Lower layers, IP, and RTP/UDP, connected by asynchronous packets (dotted red arrows). A green solid line represents the waveform output from the D/A converter to a speaker (Spkr). Reference points are marked at the input and output stages.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Legend: + +- Waveform (green solid line) +- - - Continuous digital (dashed blue line) +- - - Asynchronous packets (dotted red line) + +Figure 3/G.1020 – Destination terminal components. This block diagram shows the signal flow from a terminal input reference point through various processing stages to an ear reference point. The top path consists of De-jitter buffer, De-packetize, Decoder & PLC, and D/A converter, connected by continuous digital signals (dashed blue arrows). The bottom path consists of Physical interface, Lower layers, IP, and RTP/UDP, connected by asynchronous packets (dotted red arrows). A green solid line represents the waveform output from the D/A converter to a speaker (Spkr). Reference points are marked at the input and output stages. + +**Figure 3/G.1020 – Destination terminal components** + +## 7.1 Discussion of destination packet processing + +Figure 4 depicts the process through which IP packet parameters/impairments (transfer delay, delay variation, and packet loss and errors) can be mapped to application layer performance in terms of overall loss and delay. + +![Figure 4/G.1020 – Mapping IP packet performance to application layer. This diagram illustrates the mapping of network impairments to application layer performance. It shows layers from IP parameters/impairments up to overall application layer parameters. A de-jitter buffer is shown as a threshold for delay variation. Packets with delay variation below the threshold are accommodated (white area), while those above are lost (black area). The diagram includes labels for Delay, Loss, Error checking, and a threshold line.](9b9d2abd741ed4bafe7f78f89961c663_img.jpg) + +The diagram shows the following layers and components: + +- Overall parameters at application layer (top level) +- RTP +- UDP +- IP parameters/impairments (bottom level) + +Key elements include: + +- Delay:** Indicated at the bottom and top levels. +- Loss:** Indicated at the top level. +- Error checking:** Indicated at the UDP layer. +- De-jitter buffer:** A buffer that acts as a threshold for delay variation. +- Threshold:** A vertical line separating the 'Low' and 'High' delay variation ranges. +- Delay variation:** Ranges from 'Low' to 'High' at the IP layer. +- Loss/Errors:** Indicated at the IP layer. + +Figure 4/G.1020 – Mapping IP packet performance to application layer. This diagram illustrates the mapping of network impairments to application layer performance. It shows layers from IP parameters/impairments up to overall application layer parameters. A de-jitter buffer is shown as a threshold for delay variation. Packets with delay variation below the threshold are accommodated (white area), while those above are lost (black area). The diagram includes labels for Delay, Loss, Error checking, and a threshold line. + +**Figure 4/G.1020 – Mapping IP packet performance to application layer** + +At the bottom of the figure, packets arrive with various impairments due to the source terminal and network(s), or never arrive (lost). The arriving packets are processed as they move up the protocol stack to remove as much impairment as possible. We show that some forms of impairment (errors, jitter) map into other impairments (overall loss, overall delay). + +Figure 4 captures the trade-off between application level delay and loss as a threshold on the range of delay variation based on the size of the de-jitter buffer. Packets with delay variation in the "white" range are accommodated, while packets with larger variation (in the "black" range) would + +be discarded. A larger de-jitter buffer can accommodate packets with greater delay variation, hence, fewer packets would be lost overall at the expense of larger overall delay. Conversely, a smaller de-jitter buffer will produce less overall delay, but expose a larger fraction of packets to be discarded by the terminal and increase the overall loss. + +## 7.2 Taxonomy of de-jitter buffer types/parameters and models + +There are two main types of de-jitter buffers, fixed length and adaptive length. De-jitter buffers can be constructed in many different ways, including the following attributes identified in Table 2. The values of applicable de-jitter buffer parameters must be known when assessing the performance of a system. + +**Table 2/G.1020 – De-jitter buffer types and parameters** + +| Type | Attributes | Possibilities | | +|----------------------|-------------------------------------------------|--------------------------------------------|-----------------------------------------------------------------------------------------------------------| +| Fixed (and adaptive) | Size (configure maximum and nominal or minimum) | Integer number of packets | Fractional number of packets | +| Adaptive | Control | Timed delay if no over/under flow | Evaluate loss ratio (configure lowest acceptable threshold, and minimum packet count between adjustments) | +| | Adjustment | Timed | Silence gaps only | +| | Initialization | First packet | Small sample | +| | Adjustment granularity | Packet size | Fraction of packet size | +| | Restores packet order | Yes | No | +| | Voiceband data mode | Detect 2100 Hz tone, set to maximum length | None | + +### 7.2.1 Destination terminal delay and loss assessment + +The primary contributors to delay are variable sources. This clause illustrates how the de-jitter buffer size and network IP packet delay variation overlap, and how one must carefully accumulate specific delay statistics to achieve the correct delay totals. + +![Figure 5/G.1020 – Delay of packet networks and network elements. This diagram illustrates the cumulative delay of a packet through various network elements. It shows four main stages: Source delays (including packetization and minimum additional source delay), Network transfer delay (with minimum and 99.9%-tile transfer delay), De-jitter buffer (which accommodates delay variation from network and source terminal), and Other destination delays (including minimum playout buffer and DSP & other queuing).](12de9b926df0384ec07702671827c9cd_img.jpg) + +The diagram shows the following components and their contribution to total delay: + +- Source delays:** Includes 'Packetization' and 'Minimum additional source delay'. +- Network transfer delay:** Divided into 'Minimum transfer delay' and '99.9%-tile transfer delay'. +- De-jitter buffer:** Labeled 'Accommodates delay variation from network and source terminal'. +- Other destination delays:** Includes 'Minimum/playout buffer' and 'DSP & other queuing'. + +The diagram is labeled G.1020(06)\_F05. + +Figure 5/G.1020 – Delay of packet networks and network elements. This diagram illustrates the cumulative delay of a packet through various network elements. It shows four main stages: Source delays (including packetization and minimum additional source delay), Network transfer delay (with minimum and 99.9%-tile transfer delay), De-jitter buffer (which accommodates delay variation from network and source terminal), and Other destination delays (including minimum playout buffer and DSP & other queuing). + +**Figure 5/G.1020 – Delay of packet networks and network elements** + +Figure 5 shows some of the elements of a VoIP path that contribute to end-end delay. At the sender, packetization time can be significant. There is usually a variable delay as packets traverse the network. At the receiver, the de-jitter buffer exists to accommodate the delay variation and deliver a continuous payload stream. We note that packets with the minimum source and network delay spend the maximum time in the de-jitter buffer; likewise packets that encounter delays longer than the minimum spend less time in the buffer. There is also some minimum amount of time each packet must spend in a buffer at the receiver; possibly as long as an entire packet. + +The following subclauses give an overview of the process to combine the IP layer loss and delay with the additional contributions from destination terminal higher-layer functions, such as the de-jitter buffer. + +#### **7.2.1.1 Loss** + +Depending on the type of de-jitter buffer, there will be some criteria for determining whether or not each specific packet in a flow is accommodated or discarded. The result can completely change the distribution of overall packet losses. For example, if random bit errors are causing packets to fail the UDP checksum, then packet losses will have a random distribution as they proceed to the application layer. But, if several consecutive packets experience excessive delays, then the additional discards due to the limitations of the de-jitter buffer will make the overall loss distribution appear bursty rather than random. Therefore, categorization of the loss distribution must take place at the application layer (using techniques such as in Annex B, or the burst ratio, see Appendix I/G.113), before estimation of application performance with tools such as the E-model (see ITU-T Rec. G.107). + +There are circumstances where packet order may change during network transfer. Some de-jitter buffers are unable to restore order to these reordered packets (ITU-T Rec. Y.1540) and, in this case, they are designated as discarded packets. + +#### **7.2.1.2 Delay** + +The correct value of buffer delay to combine with the other delays depends on the descriptive statistics available. For example, the mean network delay should be summed with the average de-jitter buffer occupation time (and other delays) to obtain an overall average delay. This method allows for buffer adaptation, needing only the average queuing time for all packets in the assessment time interval. On the other hand, if only the minimum network delay is known, it should be summed with the maximum de-jitter buffer occupation (or size used, and other delays) to give an overall delay. + +We next consider initialization for a fixed-size de-jitter buffer. If the first packet to arrive has the minimum transfer delay, then the receiver will buffer the packet for the entire time requested, and buffering size will be as expected. Fortunately, many packets arrive at or near the minimum transfer time, so this case has a fair likelihood. + +On the other hand, if the first packet has a rather long delay, then more buffer space will be needed to accommodate the "early" arrival of packets at or near the minimum transfer time, and the de-jitter buffer will contribute more than the expected delay to the overall calculation. + +#### **7.2.1.3 Fixed de-jitter buffer and destination terminal model** + +The simplest effective model of loss due to a fixed de-jitter buffer is to designate as discarded all packets whose delay is greater than the minimum transfer delay for the packet stream plus the (fixed) de-jitter buffer length. + +The following procedure provides a mapping between the IP and application layers, assuming fixed length de-jitter buffers for destination terminal performance assessment. + +- 1) Designate as lost all packets failing the UDP Checksum. +- 2) Designate as discarded all packets whose delay is greater than the minimum transfer delay for the packet stream plus the (fixed) de-jitter buffer length, or whose delay is less than the established minimum. +- 3) Sum the mean network delay (IPTD) with the average source and destination terminal delay to obtain an overall average delay, OR, sum the minimum source terminal delay and the minimum network delay with the maximum destination terminal delay (reflecting the maximum de-jitter buffer occupation when network jitter is present, or maximum size used). + +In step 2 above, the minimum transfer delay should be evaluated over short intervals (provisionally a value of 10 seconds is used). The minimum for the first interval is used throughout, unless the short term minimum grows beyond the accommodation range of the buffer. In this case, no packets will be delivered to the upper layers and the de-jitter buffer must be reset to the new minimum, as would likely occur in practice. Alternatively, if the short term minimum should fall to a value where a high percentage (provisionally 50%) of packets would be designated lost due to early arrival, the de-jitter buffer must be reset to the new minimum. + +When calculating the overall impairment contribution of a fixed de-jitter buffer, the distribution of delay variation determines the proportion of packets that would be discarded. The distribution of packet delays that are accommodated (not discarded) can be used to calculate the mean de-jitter buffer occupation delay, as follows: + +$$\text{Mean occupation delay} = [\text{De-jitter Buffer Size}] - (\text{Mean Delay of Accom. Packets} - \text{Min. Delay})$$ + +This mean delay can be added with other destination terminal delay constants to produce an estimate of the mean destination terminal delay. If the exact delay distribution is not available, then there is agreement that a value of half the de-jitter buffer size may be substituted for the mean occupation delay in calculations supporting network planning. + +If the maximum destination terminal delay is needed in calculations, then the maximum de-jitter buffer size can be added with other destination terminal delay constants to produce an estimate of the maximum delay. + +#### **7.2.1.4 Adaptive de-jitter buffer model** + +The fixed de-jitter buffer in item 2 above may be replaced with an adaptive de-jitter buffer emulation, as described in this clause when a time series of packet stream information is at hand. + +The time series of packet arrivals may be used with an adaptive de-jitter buffer emulator to determine the buffer size dynamics and the mean de-jitter buffer occupation time (delay) over the series. This mean delay can be combined with other destination terminal delay constants to produce an estimate of the mean destination terminal delay. + +An example of an adaptive de-jitter buffer emulator is provided in Annex C. + +### **7.2.2 Destination terminal loss-related parameters** + +This clause defines two key parameters used in RTCP-XR [RFC 3611] reports, loss rate and discard rate, and several supporting terms. The definitions of these parameters are somewhat unique because they must be based solely on information present at the receiver, while most definitions of packet loss include sender knowledge and receiver observation. The principle ambiguity is avoided by declaring loss only when there is certainty that there is a gap in the received sequence numbers (e.g., when a packet with a larger than expected number arrives), as this is evidence that the sender did not simply stop sending. + +#### **7.2.2.1 Packet play-out time** + +The play-out time for any packet is determined by adding a fixed amount of time to the RTP timestamp. This added time includes the time for the packet to traverse the network and any buffering applied at the receiver, so that the play-out time is the instant the packet is removed from the buffer for decoding or other processing before presentation. Sequence numbers and scheduled play-out times are paired and tracked throughout the life of the stream. + +#### **7.2.2.2 Discard window** + +The discard window is the time interval for acceptable packet arrival referenced to the play-out time, possibly having asymmetric tolerance for early or late arrival. + +#### **7.2.2.3 Discarded packets** + +When a packet arrives and its play-out time is calculated (by adding a fixed time to the timestamp), the packet is declared discarded if the limits of the discard window have been exceeded. + +#### **7.2.2.4 Maximum waiting time for lost packets** + +The maximum waiting time for any packet is determined by adding a fixed amount of time to the play-out time estimated for that packet. This time will typically be significantly longer than the discard window as applied to late packets. + +#### **7.2.2.5 Lost packets** + +When the play-out time for a given packet is past by more than the maximum waiting time, and a packet with a larger sequence number has arrived, then the packet is declared lost. + +#### **7.2.2.6 Dimensions for evaluation** + +In the parameters above, time is expressed in seconds. It would be possible to evaluate these same parameters using the dimensions of packets, providing that each packet represents a fixed amount of play-out time (as is usually the case in VoIP). For example, the discard window would be expressed in packets using their sequence numbers, and if a packet arrives having a sequence number outside the bounds of the discard window, it is discarded. The maximum waiting time would instead be expressed as a number of packets with respect to the sequence number of the current packet being played-out. + +#### **7.2.2.7 Loss ratio for use in the RTCP-XR loss rate parameter** + +The ratio of the total number of packets declared lost to the total number expected from the beginning of reception to the reporting time, where the total number expected is determined from the earliest and latest sequence numbers. + +The unit of this parameter is a ratio of lost to total packets. + +#### **7.2.2.8 Discard ratio for use in the RTCP-XR discard rate parameter** + +The ratio of the total number of packets declared discarded to the total number expected from the beginning of reception to the reporting time, where the total number expected is determined from the earliest and latest sequence numbers. + +The unit of this parameter is a ratio of discarded to total packets. + +### **7.2.3 Destination terminal delay** + +The destination terminal delay is the interval defined as beginning when the first bit of a packet representing a waveform signal enters the terminal input reference point and ending when the corresponding decoded, depacketized signal exits the ear reference point. When appropriate, the receive electrical reference point may be substituted for the ear reference point. + +NOTE – This delay may vary if an adaptive de-jitter buffer is present, and appropriate statistics should be applied to summarize the variation. + +Since, by definition, the source terminal delay includes the entire packetization/depacketization time, destination terminal packet test signals should be constructed such that they occupy the earliest part of the payload. In this way, source and destination terminal delay measurements will be conducted at equivalent moments with respect to packetization time. + +The unit of measure for destination terminal delay is time in seconds. + +## 7.3 System frequency offset, using destination clock as reference + +The system frequency offset may be assessed by monitoring sequence number increment per unit time or accumulated time-stamp offset, and is a measure of the difference between source and destination analogue/digital conversion clock accuracy. The relative frequency offset between the source and destination clocks may be specified as: + +$$\frac{\Delta f}{f_{Destination}} = \frac{f_{Source} - f_{Destination}}{f_{Destination}}$$ + +This frequency offset may be used to determine the rate of buffer overflow or underflow events at the destination terminal, usually resulting in additional packet losses, by noting that the fractional frequency offset is equivalent to the time shift ( $\Delta t$ ) over an observation interval ( $T$ ). + +$$\frac{\Delta f}{f_{Destination}} = -\frac{\Delta t}{T}$$ + +(noting that frequency and time period differences have a negative relationship). For example, assume that the source frequency is 7999.997 Hz, the destination frequency is 8000.001 Hz, and the de-jitter buffer length is 20 ms. Since the destination's D/A converter clock is reading information faster than the source supplies it, the de-jitter buffer will eventually empty, or underflow. At a relative offset of: + +$$\frac{7999.997 - 8000.001}{8000.001} = -5 \times 10^{-7}$$ + +(where the minus sign indicates that the source clock pulses occur slower than the corresponding pulses at the destination), the time shift equal to the entire de-jitter buffer will accumulate in an observation interval of: + +$$T = \frac{-(\Delta t = 0.02)}{-5 \times 10^{-7}} = 40\,000 \text{ sec} = 667 \text{ min}$$ + +System frequency offset is a unit-less quantity, often specified as a fraction or in parts per million. + +## 7.4 Packet loss concealment (type, delay) + +Many standardized speech coders have a native Packet Loss Concealment (PLC), and it is sufficient to specify whether or not the PLC is on or off, and account for any additional delay. For example, Appendix I/G.711 adds at least 3.75 ms algorithmic delay, and possibly more depending on implementation. This PLC may be used with other waveform coders, such as G.726. + +Many forms of non-standardized PLC have emerged in practice, particularly for G.711 and other waveform coders. If these are used, the specific PLC algorithm and delay should be specified. + +Note that a PLC that sounds best to human users may not meet the needs of voiceband modem carrier detectors. If there is a signal classifier for voiceband data or fax modems, and a special PLC is selected to improve their operation on packet networks, then the PLC type and signal classification method should be specified. + +# 8 Overall performance parameters + +## 8.1 Overall delay (including source, network and destination) + +Following the analysis of the de-jitter buffer and other destination terminal components, as described throughout 7.2.1 and illustrated in Figure 5, it is possible to combine them with the delay of the source terminal and network(s) to determine the system's overall delay. The following formulas are acceptable, and their use is determined by the specific delay statistics available for computation. + +When the mean delays for all components are at hand: + +$$\text{Overall\_Mean\_Delay} = \text{mean}(\text{source\_delay}) + \text{mean}(\text{net\_delay}) + \text{mean}(\text{destination\_delay})$$ + +As Figure 5 clearly illustrates, the minimum delays for source terminal and network can be combined with the maximum destination terminal delay to obtain an estimate using constants: + +$$\text{Overall Delay (constant)} = \text{min}(\text{source\_delay}) + \text{min}(\text{net\_delay}) + \text{max}(\text{destination\_delay})$$ + +When measured directly, the overall delay is the interval defined from the time that a signal enters the mouth reference point and ending at the time when the corresponding signal exits the ear reference point (or equivalent reference points). + +One method for direct measurement of overall delay has been documented in Annex B of [10]. + +Several examples of the overall mean delay calculation are present in Appendix VII/Y.1541. These examples utilize various network configurations and reference terminals with several packet sizes, de-jitter buffers, and forms of packet loss concealment. Appendix VII/Y.1541 goes on to calculate E-model R values for each of these cases [G.107]. + +The unit of measure for overall delay is seconds. + +## 8.2 End System Delay + +This clause defines the End System Delay parameter used in RTCP-XR [RFC 3611] reports. + +The end system delay is defined as the sum of the Source delay and Destination delay for the end system reporting the value, and includes the sample accumulation delay, encoding delay, de-jitter buffer delay, decoding delay, and play out delay. The value may be estimated or measured. + +The unit of measure for end system delay is seconds. + +## 8.3 Round Trip Delay + +This clause defines the Round Trip Delay parameter used in RTCP-XR [RFC 3611] reports. + +The round trip time is defined as the time a packet takes to travel from the source RTP interface to the destination RTP interface and return to the source RTP interface. The most recently calculated time is reported. + +The unit of measure for round trip delay is seconds. + +## 8.4 Time-scale discontinuities in post-de-jitter and PLC stream + +A time-scale discontinuity is defined as a sudden change in the overall delay, measured from the mouth reference point to the ear reference point. This parameter captures how often the user's time reference shifts, due to the network path, the de-jitter buffer, or both. + +The units of measure for time-scale discontinuities are seconds, and an event count. + +## 8.5 Overall (frame/packet) loss (including network and destination) + +This parameter may be expressed in terms of packets, or coder frames. It is important to understand the relationship between frame loss and packet loss. For example, when two frames are combined in each packet, then every packet lost implies a burst of two frame losses and the decoder/PLC must attempt recovery under these more difficult circumstances than the isolated single frame loss. + +### 8.5.1 Overall (frame/packet) loss ratio + +The overall loss ratio for an evaluation interval is defined as follows: + +Overall Loss Ratio = + +$$1 - \frac{(\text{Total\_pkt\_sent} - \text{Lost\_net} - \text{Lost\_error\_check} - \text{Discarded\_de-jitter-buffer} - \text{Discarded\_reordering})}{\text{Total\_pkt\_sent}}$$ + +The unit of this parameter is a ratio of lost to total packets (or frames). + +### 8.5.2 Overall (frame/packet) loss model + +In order to assess the impact of losses and discards on VoIP applications, it is useful to consider distribution of these impairments over time. Typical approaches include the Gilbert-Elliott model and similar Markov-based models. RFC 3611 specifies the use of a Gilbert-Elliott model to describe packet loss and discard distribution and gives an example of a four-state Markov model to derive these parameters. Annex B provides a description of these models, and gives an example of a typical packet loss/discard distribution. The typical output parameters are the average gap length and loss/discard density, and the average burst length and loss/discard density. + +### 8.5.3 Overall consecutive (frame/packet) loss event count + +After examining a stream of packets sent according to [9], and a set of successive packets have been designated as lost or discarded according to all the relevant loss/discard criteria in the overall loss ratio parameter, then the length of the event should be specified as the number of packets lost in sequence. This length should be specified separately for each event, in units of packets. The count of each event size should also be provided as a result. Sequence numbers contained in packet headers may be used to aid in this measurement. + +### 8.5.4 Pitfalls and errors in calculating overall parameters + +One simplified approach to obtain the overall end-to-end delay has been to take the mean IP packet transfer delay, and combine it with constants for other elements in the mouth-to-ear path. This procedure may produce errors because of variable delays in some terminal components (e.g., the de-jitter buffer), or because the variable delay elements are ignored. + +Another potential pitfall would be to use the packet loss ratio as measured by a test receiver that allows, for example, 3 seconds before declaring a packet lost, thereby underestimating the loss ratio. A typical de-jitter buffer would have much less tolerance for long delays beyond the norm. Hereto, knowledge of the de-jitter buffer figures prominently in the mapping between IP packet performance and loss at the application layer. + +# Annex A + +## VoIP gateway-specific reference points and performance parameters + +## A.1 Introduction + +VoIP gateways are usually deployed to interconnect packet and circuit switched networks and require new reference points for delay and other parameters. This annex defines the gateway-specific reference points and parameters. + +## A.2 Definitions + +This annex defines the following terms: + +**A.2.1 packet input reference point:** A measurement point in the physical medium connecting an IP network to a gateway that is crossed as IP packets leave the IP network and enter the gateway. This measurement point is as close to the terminal as possible. + +**A.2.2 packet output reference point:** A measurement point in the physical medium connecting a gateway to an IP network that is crossed as IP packets leave the gateway and enter the IP network. This measurement point is as close to the gateway as possible. + +**A.2.3 TDM input reference point:** A measurement point in the physical medium connecting a Time Division Multiplex Network to a VoIP gateway. Signals that cross this point are packetized and enter the IP network. This measurement point is as close to the gateway as possible. + +**A.2.4 TDM output reference point:** A measurement point in the physical medium connecting a gateway to a Time Division Multiplex Network. Signals that cross this point are carried to the end terminal. This measurement point is as close to the gateway as possible. + +## A.3 Source gateway parameters + +This clause gives the relevant source gateway packet parameters that have a direct effect on perceived speech and voiceband application quality. Figure A.1 indicates the positions of measurement points and system components. + +![Figure A.1/G.1020 – Source gateway diagram and reference points. The diagram illustrates the signal flow from a microphone to a TDM gateway and then into an IP network. It shows three horizontal paths: a green solid line for 'Waveform' (from Mic & terminal to A/D converter), a blue dashed line for 'Continuous digital' (from A/D converter through Source encoding, Channel encoding, and TDM to the TDM gateway), and a red dotted line for 'Asynchronous packets' (from the TDM gateway through TDM DMUX, Channel encoding, Packetization, RTP/UDP, IP, Lower layers, and Physical interface). Reference points are marked: 'Mouth reference point' at the microphone, 'TDM input reference point' at the TDM gateway input, and 'Packet output reference point' at the Physical interface output. A legend at the bottom left defines the line types: green solid for Waveform, blue dashed for Continuous digital, and red dotted for Asynchronous packets. The diagram is labeled G.1020(06)_FA.1 at the bottom right.](e05c1a13b44ab41505609d82b00cf4df_img.jpg) + +Figure A.1/G.1020 – Source gateway diagram and reference points. The diagram illustrates the signal flow from a microphone to a TDM gateway and then into an IP network. It shows three horizontal paths: a green solid line for 'Waveform' (from Mic & terminal to A/D converter), a blue dashed line for 'Continuous digital' (from A/D converter through Source encoding, Channel encoding, and TDM to the TDM gateway), and a red dotted line for 'Asynchronous packets' (from the TDM gateway through TDM DMUX, Channel encoding, Packetization, RTP/UDP, IP, Lower layers, and Physical interface). Reference points are marked: 'Mouth reference point' at the microphone, 'TDM input reference point' at the TDM gateway input, and 'Packet output reference point' at the Physical interface output. A legend at the bottom left defines the line types: green solid for Waveform, blue dashed for Continuous digital, and red dotted for Asynchronous packets. The diagram is labeled G.1020(06)\_FA.1 at the bottom right. + +Figure A.1/G.1020 – Source gateway diagram and reference points + +We note that some gateways will include coders that provide bit rate compression, while others will simply packetize the PCM waveform, or provide other processing to the voiceband signals such as Fax Demod/Remod. + +Most of the source terminal parameters defined in clause 5 are relevant to source gateways. Some parameters require the following reference point substitutions in Table A.1. + +**Table A.1/G.1020 – Source Reference Point Substitution** + +| Source Terminal | Substitute Source Gateway Reference Point | +|---------------------------------|-------------------------------------------| +| Mouth Reference Point | TDM Input Reference Point | +| Send Electrical Reference Point | TDM Input Reference Point | +| Terminal Output Reference Point | Packet Output Reference Point | + +The source terminal to source gateway parameter mapping is as follows: + +**Table A.2/G.1020 – Source Parameter Mapping** + +| Source Terminal Parameter | Source Gateway Parameter | +|---------------------------------|--------------------------------| +| Source Terminal Delay | Source Gateway Delay | +| Source Terminal Delay Variation | Source Gateway Delay Variation | + +Parameters such as Packet Information Field Size require no modifications. + +## A.4 Destination gateway parameters + +This clause gives the relevant destination gateway packet parameters that have a direct effect on perceived speech and voiceband application quality. Figure A.2 indicates the positions of measurement points and system components. + +![Figure A.2/G.1020 – Destination gateway diagram and reference points. The diagram shows the signal flow from a TDM gateway to an ear reference point, and from a packet input reference point through various layers to the same ear reference point. The top path (TDM) consists of TDM DMUX, Decoder, D/A converter, and Terminal & spkr. The bottom path (Packet) consists of Physical interface, Lower layers, IP, RTP/UDP, De-jitter buffer, De-packetize, Decoder & PLC, and TDM. Reference points are marked with colored lines: green for waveform, dashed blue for continuous digital, and dotted red for asynchronous packets.](db5ab5d386827a5d5f5fad0f45612b90_img.jpg) + +The diagram illustrates the destination gateway architecture and measurement reference points. It is divided into two main signal paths: + +- TDM Path (Top):** A TDM gateway connects to a TDM DMUX, which outputs a continuous digital signal (dashed blue line) to a Decoder. The Decoder outputs to a D/A converter, which produces a waveform (green line) to a Terminal & speaker. The 'Ear reference point' is located at the speaker. +- Packet Path (Bottom):** A 'Packet input reference point' is located at the Physical interface. Asynchronous packets (dotted red line) flow from the Physical interface through Lower layers, IP, and RTP/UDP. The RTP/UDP layer is labeled 'G.1020(06)\_FA.2'. The packets then pass through a De-jitter buffer, De-packetize, Decoder & PLC, and TDM block. The TDM block outputs a continuous digital signal (dashed blue line) to the same D/A converter and Terminal & speaker as the TDM path. A 'TDM output reference point' is indicated at the output of the TDM block in the packet path. + +**Legend:** + +- Green solid line: Waveform +- Dashed blue line: Continuous digital +- Dotted red line: Asynchronous packets + +Figure A.2/G.1020 – Destination gateway diagram and reference points. The diagram shows the signal flow from a TDM gateway to an ear reference point, and from a packet input reference point through various layers to the same ear reference point. The top path (TDM) consists of TDM DMUX, Decoder, D/A converter, and Terminal & spkr. The bottom path (Packet) consists of Physical interface, Lower layers, IP, RTP/UDP, De-jitter buffer, De-packetize, Decoder & PLC, and TDM. Reference points are marked with colored lines: green for waveform, dashed blue for continuous digital, and dotted red for asynchronous packets. + +**Figure A.2/G.1020 – Destination gateway diagram and reference points** + +Most of the destination terminal parameters defined in clause 7 are relevant to destination gateways. Some parameters require the reference point substitutions in Table A.3. + +**Table A.3/G.1020 – Destination Reference Point Substitution** + +| Destination Terminal | Substitute Destination Gateway Reference Point | +|------------------------------------|------------------------------------------------| +| Ear Reference Point | TDM Output Reference Point | +| Receive Electrical Reference Point | TDM Output Reference Point | +| Terminal Input Reference Point | Packet Input Reference Point | + +The destination terminal to destination gateway parameter mapping is as follows. + +**Table A.4/G.1020 – Destination Parameter Mapping** + +| Destination Terminal Parameter | Destination Gateway Parameter | +|--------------------------------|-------------------------------| +| Destination Terminal Delay | Destination Gateway Delay | + +Parameters such as Packet Loss Concealment require no modifications. + +## **A.5 Overall delay** + +When a gateway is present in the end-end path, the additional delay in the TDM network between the Mouth or Ear Reference point and the gateway must be included in the overall delay. The TDM network elements usually have fixed delays, so they can be added to the delay for the packet network components. The unit of measure for overall delay is seconds. + +# **Annex B** + +## **Packet loss distributions and packet loss models** + +## **B.1 Introduction** + +It is generally understood that packet loss distribution in IP networks is "bursty", however, there is less certainty concerning the use of specific loss models and, in fact, some misunderstanding related to some commonly used models, for example the Gilbert Model. This annex outlines some key packet loss models, provides some analysis of packet loss data, and discusses the degree of "fit" of models and data. + +## **B.2 Common packet loss models** + +### **B.2.1 Historical background** + +Much of the early work on loss or error modelling occurred in the 1960's in relation to the distribution of bit errors on telephone channels. + +One approach used was a Markov or multi-state model. Gilbert [B-13] appears to be the first to describe a burst error model of this type, later extended by Elliott [B-10] and [B-11] and Cain and Simpson [B-6]. Blank and Trafton [B-3] produced higher state Markov models to represent error distributions. + +Another approach was to identify the statistical distribution of gaps. Mertz [B-16] used hyperbolic distributions and Berger and Mandelbrot [B-2] used Pareto distributions to model inter-error gaps. Lewis and Cox [B-15] found that in measured error distributions there was strong positive correlation between adjacent gaps. + +Packet loss modelling in IP networks seems to have followed a similar course, although the root cause of loss (typically congestion) may be different to that of bit errors (typically circuit noise or jitter). + +### **B.2.2 Bernoulli or independent model** + +The most widely used model is a simple independent loss channel, in which a packet is lost (or bit error occurs) with a probability $P_e$ . For some large number of packets $N$ , then the expected number of lost packets is $N \times P_e$ . The loss probability can be estimated by counting the number of lost packets and dividing this by the total number of packets transmitted. + +### **B.2.3 Gilbert and Gilbert-Elliott models** + +The most widely known burst model is the Gilbert model [B-13] and a variant known as the Gilbert-Elliott model [B-10] and [B-11]. These are both two state models that transition between a "good" or gap state 0 and a "bad" or burst state 1 according to state transition probabilities $P_{01}$ and $P_{11}$ : + +- i) *Gilbert model*: + - a) State 0 is a zero loss/error state; + - b) State 1 is a lossy state with independent loss probability $P_{e1}$ ; +- ii) *Gilbert-Elliott model*: + - a) State 0 is a low loss state with independent loss probability $P_{e0}$ ; + - b) State 1 is a lossy state with independent loss probability $P_{e1}$ . + +It is often assumed that the Gilbert model lossy state corresponds to a "loss" state, i.e., that the probability of packet loss in state 1 is 1, however, this is incorrect (it would be more proper to describe this as a 2-state Markov model). This leads to analysis of packet loss burstiness in terms solely of consecutive loss which misses the effects of longer periods of high loss density. These long periods of high loss density can have significant effect on voice over IP services. + +For example, consider the following: + +Loss pattern      0000011001010110110000000000000000000000 + +*Correct application of Gilbert Model – burst length 15, burst density 60%* + +*Incorrect application of Gilbert Model – mean burst length 1.5 packets* + +### **B.2.4 Markov models** + +A Markov model is a general multi-state model in which a system switches between states $i$ and $j$ with some transition probability $p(i, j)$ . + +A 2-state Markov model has some merit in that it is able to capture very short-term dependencies between lost packets, i.e., consecutive losses [B-1], [B-4], [B-14] and [B-18]. These are generally very short duration events (say 1-3 packets in length) but occasional link failures can result in very long loss sequences extending to tens of seconds [B-5]. + +By combining the 2-state model with a Gilbert-Elliott model, it is possible to capture both very short duration consecutive loss events and longer lower density events. + + + +#### **B.2.5.3 Gap** + +A gap is the longest sequence of packets beginning and ending with a loss or the start or end of reception, where the sequences of consecutive received packets are greater than or equal to $G_{min}$ in length. The units are packets. + +#### **B.2.5.4 Burst density** + +The burst density is the fraction of RTP data packets within burst periods since the beginning of reception that were either lost or discarded. This value is expressed as a fixed point number with the binary point at the left edge of the field. It is calculated by dividing the total number of packets lost or discarded (excluding duplicate packet discards) within burst periods by the total number of packets expected within the burst periods, multiplying the result of the division by 256, limiting the maximum value to 255 (to avoid overflow), and taking the integer part. The units are the ratio of lost and discarded packets to total packets. + +#### **B.2.5.5 Gap density** + +The gap density is the fraction of RTP data packets within inter-burst gaps since the beginning of reception that were either lost or discarded. The value is expressed as a fixed point number with the binary point at the left edge of the field. It is calculated by dividing the total number of packets lost or discarded (excluding duplicate packet discards) within gap periods by the total number of packets expected within the gap periods, multiplying the result of the division by 256, limiting the maximum value to 255 (to avoid overflow), and taking the integer part. The units are the ratio of lost and discarded packets to total packets. + +#### **B.2.5.6 Burst duration** + +The burst duration is the mean of the burst periods, expressed in units of milliseconds, which have occurred since the beginning of reception. The duration of each period is calculated based upon the packets that mark the beginning and end of that period. It is equal to the timestamp of the end packet, plus the duration of the end packet, minus the timestamp of the beginning packet. If the actual values are not available, estimated values MUST be used. If there have been no burst periods, the burst duration value MUST be zero. + +#### **B.2.5.7 Gap duration** + +The gap duration is the mean of the gap periods, expressed in units of milliseconds, which have occurred since the beginning of reception. The duration of each period is calculated based upon the packet that marks the end of the prior burst and the packet that marks the beginning of the subsequent burst. It is equal to the timestamp of the subsequent burst packet, minus the timestamp of the prior burst packet, plus the duration of the prior burst packet. If the actual values are not available, estimated values MUST be used. In the case of a gap that occurs at the beginning of reception, the sum of the timestamp of the prior burst packet and the duration of the prior burst packet are replaced by the reception start time. In the case of a gap that occurs at the end of reception, the timestamp of the subsequent burst packet is replaced by the reception end time. If there have been no gap periods, the gap duration value MUST be zero. + +## **B.3 Example packet trace** + +There are two charts shown below that were obtained from analysis of an example IP trace. The first chart shows a scatter diagram of burst length versus burst weight (Gilbert model). Burst length is the distance in packets between the first and last lost packets in a burst and burst weight is the number of packets lost within the burst. It can be clearly seen that bursts of up to 100 packets in length occur, and have a typical loss density of 20-25%. + +![Figure B.2/G.1020 – Trace W3 scatter diagram of burst length vs weight for packet loss only. The plot shows burst length on the x-axis (0 to 200) and burst weight on the y-axis (0 to 100). A dense cluster of points is visible below 100 burst length and 20 burst weight, with a few outliers extending towards higher values. A linear regression line is shown starting near the origin and trending upwards to the right. The label G.1020(06)_FB.2 is in the bottom right corner.](48a08e5cabec8b75386679d8a57dec3e_img.jpg) + +Figure B.2/G.1020 – Trace W3 scatter diagram of burst length vs weight for packet loss only. The plot shows burst length on the x-axis (0 to 200) and burst weight on the y-axis (0 to 100). A dense cluster of points is visible below 100 burst length and 20 burst weight, with a few outliers extending towards higher values. A linear regression line is shown starting near the origin and trending upwards to the right. The label G.1020(06)\_FB.2 is in the bottom right corner. + +**Figure B.2/G.1020 – Trace W3 scatter diagram of burst length vs weight for packet loss only** + +The second chart shows a scatter diagram of burst length versus burst weight for losses and discards, assuming a 50 ms fixed de-jitter buffer size. This shows a much larger number of bursts indicating that jitter was a significant problem on this trace. Burst density extends out to 500 packets and mean burst density is approximately 30%. + +![Figure B.3/G.1020 – Trace W3 scatter diagram of burst length vs weight for packet loss and packet discard (50 ms jitter buffer). The plot shows burst length on the x-axis (0 to 500) and burst weight on the y-axis (0 to 200). The data points are more widely distributed than in Figure B.2, with a significant number of points between burst lengths of 200 and 500. A linear regression line is shown starting near the origin and trending upwards to the right. The label G.1020(06)_FB.3 is in the bottom right corner.](853ef5420f0432e626e83987e3f38a0b_img.jpg) + +Figure B.3/G.1020 – Trace W3 scatter diagram of burst length vs weight for packet loss and packet discard (50 ms jitter buffer). The plot shows burst length on the x-axis (0 to 500) and burst weight on the y-axis (0 to 200). The data points are more widely distributed than in Figure B.2, with a significant number of points between burst lengths of 200 and 500. A linear regression line is shown starting near the origin and trending upwards to the right. The label G.1020(06)\_FB.3 is in the bottom right corner. + +**Figure B.3/G.1020 – Trace W3 scatter diagram of burst length vs weight for packet loss and packet discard (50 ms jitter buffer)** + +## **B.4 Bibliography to Annex B** + +- [B-1] ALTMAN (E.), AVRACHENKOV (K.), BARAKAT (C.): TCP in the Presence of Bursty Losses, *Performance Evaluation* 42, pp. 129-147, 2000. +- [B-2] BERGER (J.M.), MANDELBROT (B.): A New Model for Error Clustering in Telephone Circuits, *IBM J R&D*, July 1963. +- [B-3] BLANK (H.A.), TRAFON (P.J.): A Markov Error Channel Model, *Proc. Nat Telecomm Conference*, 1973. +- [B-4] BOLOT (J.C.), VEGA GARCIA (A.): The case for FEC based error control for packet audio in the Internet, *ACM Multimedia Systems*, 1997. +- [B-5] BOUTREMANS (C.), IANNACCONE (G.), DIOT (C.): Impact of Link Failures on VoIP Performance, *Sprint Labs Technical Report IC/2002/015*. + +- [B-6] CAIN (J.B.), SIMPSON (R.S.): The Distribution of Burst Lengths on a Gilbert Channel, *IEEE Trans IT*, 15 September 1969. +- [B-7] CLARK (A.): Modelling the effects of burst packet loss and recency on subjective voice quality, *IPtel 2001 workshop*. +- [B-8] DRAJIC (D.), VUCETIC (B.): Evaluation of Hybrid Error Control Systems, *IEE Proc. F*. Vol. 131, April 1984. +- [B-9] EBERT (J-P.), WILLIG (A.): A Gilbert-Elliott Model and the Efficient Use in Packet Level Simulation, *TKN Technical Report 99-002*. +- [B-10] ELLIOTT (E.O.): Estimates of Error Rates for Codes on Burst Noise Channels, *BSTJ 42*, September 1963. +- [B-11] ELLIOTT (E.O.): A Model of the Switched Telephone Network for Data Communications, *BSTJ 44*, January 1965. +- [B-12] ETSI TIPHON TS 101 329-5 VI.1.2 (2002), *Annex E, QoS measurements for Voice over IP*. +- [B-13] GILBERT (E.N.): Capacity of a Burst Noise Channel, *BSTJ*, September 1960. +- [B-14] JIANG (W.), SCHULZRINNE (H.): Modelling of Packet Loss and Delay and their effect on Real Time Multimedia Service Quality, *NOSSDAV*, 2000. +- [B-15] LEWIS (P.), COX (D.): A Statistical Analysis of Telephone Circuit Error Data, *IEEE Trans COM-14*, 1966. +- [B-16] MERTZ (P.): Statistics of Hyperbolic Error Distributions in Data Transmission, *IRE Trans CS-9*, December 1961. +- [B-17] SANNECK (H.), CARLE (G.): A Framework Model for Packet Loss Metrics Based on Loss Runlengths, *Proc. ACM MMNCN*, January 2000. +- [B-18] YAJNIK (M.), MOON (S.), KUROSE (J.), TOWSLEY (D.): Measuring and Modelling of the Temporal Dependence in Packet Loss, *UMASS CMPSCI Tech. Report 98-78*. + +# Annex C + +## Example adaptive de-jitter buffer emulator + +## C.1 Introduction + +This example of a de-jitter buffer emulator operates by tracking the short-term minimum delay and using this to position a time window equivalent in size to the de-jitter buffer size. The actual packet arrival time is compared to the time window to determine if the packet would be discarded or accommodated. + +The output from this de-jitter buffer emulator is a packet loss/discard event associated with a count of the number of good packets (i.e., not lost or discarded), which is input to the packet loss distribution model. + +The de-jitter buffer emulation algorithm determines the delay variation for each arriving RTP packet, based on the RTP timestamp/sequence number and a local clock. This approach is preferable to measuring packet-to-packet delay variation as it: + +- i) handles out-of-order packets without requiring them to be buffered, which reduces computational complexity; +- ii) is able to detect mid-long term delay variations, due to congestion, route changes or timing drift. + +## C.2 Parameter definitions + +### C.2.1 (De-)Jitter buffer adaptive + +A logical indication (expressed in two bit positions) of whether the de-jitter buffer size is adaptive (11) or fixed/non-adaptive (10). The bit pattern (00) indicates that the mode is unknown, and (01) is reserved. + +### C.2.2 (De-)Jitter buffer Rate + +The buffer adjustment rate is the approximate time it takes for an adaptive buffer to adjust to a step change in delay variation range from 30 ms to 100 ms. The rate, R, is calculated according to the following formula: adjustment time = $2 * R * (\text{packet payload size, in milliseconds})$ . + +### C.2.3 (De-)Jitter buffer Nominal Delay + +This is the current setting of buffering time applied to a packet that arrives exactly on time, meaning that the packet encounters exactly the same transfer delay as the reference packet used to align the de-jitter buffer (the first packet in the emulator below). The unit of measure is milliseconds. + +### C.2.4 (De-)Jitter buffer Maximum Delay + +This is the buffering time applied to a packet that represents the earliest arrival time for a packet that would not be discarded, meaning that the packet encounters a very short transfer delay with respect to the reference packet, but is still buffered and played-out successfully. The unit of measure is milliseconds. + +### C.2.5 (De-)Jitter buffer Absolute Maximum Delay + +This is the largest value of buffering delay that can be applied to a received packet, under adaptive buffer control. With fixed buffer control, this parameter is equal to the Maximum Delay, defined above. This is usually a configuration parameter. The unit of measure is milliseconds. + +## C.3 De-jitter buffer emulation + +The de-jitter buffer emulator operates as follows: + +*The first arriving RTP packet is the initial reference point with RTP timestamp $R_{ref}$ .* + +*Set Nominal equal to the delay for packets arriving on time (configuration parameter).* + +*Set Maximum Delay equal to the number of packets times the packet size (configuration parameter).* + +*Define early window = Maximum – Nominal.* + +*Define late window = Nominal.* + +*For each RTP packet associated with a stream that passes the monitoring point:* + +*Associate a local timestamp $L$ with the arrival time of the RTP packet* + +*Identify the RTP timestamp $R$ of the packet* + +*Estimate the expected arrival time of the RTP packet based on the reference RTP packet using the expression $L_{expected} = L_{ref} + (R - R_{ref})$* + +*Estimate the delay variation of the RTP packet as $D = L - L_{expected}$* + +*If $D < \text{early window}$ then* + +*mark the packet as discarded* + +*reset the reference point to this packet* + +*If $D > \text{late window}$ then* + +*mark the packet as discarded* + +*If packet is a duplicate of an already received packet, then silently discard* + +*Maintain a sliding window of 32 packets, ordered by sequence number, by default marked as lost – mark packets within this window as accommodated or discarded* + +*At the end of the window – identify packets as lost/discarded or accommodated* + +The early/late window can be dynamically adjusted to suit adaptive de-jitter buffer behaviour. + +Adjustment algorithm: + +*Define threshold $T1$ equal to the lowest unacceptable rate of discards (a configurable parameter)* + +*Define threshold $T2$ equal to the period between de-jitter buffer size downward adjustments (in packets, a configurable parameter)* + +*Maintain a running average of late discards $C1$ , with a scaling factor, $S$ (typically 15)* + +*$C1 = (C1 \times (S - 1) + D)/S$ where $D$ is 1 if packet discarded and 0 if not* + +*Maintain a count of the packets received since the last late discard $C2$* + +*if $C1$ exceeds a threshold, $T1$ , and the buffer is less than the maximum then increase the buffer size, and reset $C1$ ;* + +*if $C2$ exceeds a threshold, $T2$ , and the buffer is more than the minimum then reduce the buffer size, and reset $C2$ .* + +The maximum value of the time window, or de-jitter buffer maximum length, must be specified so that the emulator cannot grow the buffer to extreme values that would not be possible in practice. + +# Appendix I + +## List of RTCP XR metrics + +This appendix gives the mapping between RTCP-XR metrics and various ITU-T Recommendations, with a detailed description of the action taken to include these metrics in the main body of the Recommendation. + +| RTCP XR Metrics | Existing ITU-T references | Action | +|--------------------------------------|---------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Loss rate | Y.1540: IPLR is at the IP layer, need new definition for the RTP layer computed at receiver-only. | Definition added to 7.2.2, based on 4.7.1/RFC 3611. There are 2 alternative frameworks included for other definitions needed, such as the definition of a lost packet. | +| Discard rate | Mentioned in G.1020 Overall Loss, but not defined. | Definition added to 7.2.2, based on 4.7.1/RFC 3611. | +| burst density | The model is already defined in Annex B. | Define a loss model, based on the Gilbert-Elliott model.
Definitions in B.2.5. | +| gap density | | | +| burst duration | | | +| gap duration | | | +| G min | | | +| Round trip delay | | Take the definition of RFCs 3550 and 3611 (Needs refinement, added to 8.3) | +| End-system delay | Source Terminal and Destination Terminal Delay of G.1020 sum to this value. | Need to work on a precise definition (based on the one in RFC 3611, added to 8.2). | +| Signal level | P.56, P.561 | Promote the use of these standard methods. | +| Noise level | O.41, P.561 | | +| Residual echo return loss | G.122 for echo loss, G.168 (SG 16) for residual echo level | | +| R factor | G.107 | Need for specific default values | +| External R factor | G.107 | Need for specific default value | +| MOS LQ | P.862, P.563, P.564 | A field is missing in RTCP XR VoIP Metrics Report Block to define what model has been used | +| MOS CQ | P.562 (CCI), G.107 | A field is missing in RTCP XR VoIP Metrics Report Block to define what model has been used | +| Packet loss concealment | G.1020 has material on this in 7.4. | | +| Jitter buffer adaptive | Clause 7.2 covers most of the jitter buffer parameters. | | +| Jitter buffer rate | | There is a de-jitter buffer model in Annex C, and definitions have been added. (This was formerly App. II) | +| Jitter buffer nominal delay | | | +| Jitter buffer maximum delay | | | +| Jitter buffer absolute maximum delay | | | + +# BIBLIOGRAPHY + +- [1] [RFC 3550], RTP (2003), *A Transport Protocol for Real-Time Applications.* +- [2] [RFC 2330] (1998), *Framework for IP Performance Metrics.* +- [3] [RFC 2678] (1999), *IPPM Metrics for Measuring Connectivity.* +- [4] [RFC 2679] (1999), *A One-way Delay Metric for IPPM.* +- [5] [RFC 2680] (1999), *A One-way Packet Loss Metric for IPPM.* +- [6] [RFC 2681] (1999), *A Round-trip Delay Metric for IPPM.* +- [7] [RFC 3357] (2002), *One-way Loss Pattern Sample Metrics.* +- [8] [RFC 3393] (2002), *IP Packet Delay Variation Metric for IP Performance Metrics IPPM.* +- [9] [RFC 3432] (2002), *Network performance measurement for periodic streams.* +- [10] ETSI [TS 101 329-5] V1.1.2 (2002), *TIPHON release 3, End-to-End Quality of Service in TIPHON Systems, Part 5 Quality of Service (QoS) Measurement Methodologies.* + + + + + +# **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|----------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.1021-201207-I_PDF-E/042733dc5e8e7f5f30b60adba3266cde_img.jpg b/marked/G/T-REC-G.1021-201207-I_PDF-E/042733dc5e8e7f5f30b60adba3266cde_img.jpg new file mode 100644 index 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+ +Recommendation ITU-T G.1028 + +**ITU-T** + +![ITU logo: A globe with a red lightning bolt and the text 'ITU International Telecommunication Union'.](1d7527f4316cfe2d342b08d1653d1592_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a stylized globe with a red lightning bolt striking across it. To the right of the globe, the text "ITU" is written in a bold, blue font, and below it, "International Telecommunication Union" is written in a smaller, blue font. + +ITU logo: A globe with a red lightning bolt and the text 'ITU International Telecommunication Union'. + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.1028 + +# End-to-end quality of service for voice over 4G mobile networks + +## Summary + +Recommendation ITU-T G.1028 provides guidelines concerning the key aspects impacting end-to-end performance of managed voice applications over LTE networks and how they can be properly assessed using current elements of knowledge. + +Some typical end-to-end scenarios are described, involving cases with LTE access at both sides of the communication, or with a different access technology at one side (wireless or wireline access). These scenarios are based on typical reference connections defined in this Recommendation, composed of various segments, including: terminal, wireless access, backhaul network, core network. Considerations regarding the sharing of the budget of some key parameters and the location where they can be assessed across these segments are provided. + +As far as the specific impact of the circuit switched fall back (CSFB) procedure on quality of service (QoS) is concerned, dedicated information and material is available in the companion Recommendation ITU-T G.1028.2, *Assessment of the LTE circuit switched fall back – Impact on voice quality of service*. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.1028 | 2016-04-06 | 12 | 11.1002/1000/12748 | +| 2.0 | ITU-T G.1028 | 2019-06-29 | 12 | 11.1002/1000/13927 | + +## Keywords + +Quality of service, QoS, telephony, voice, VoLTE, 4G, LTE. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|--------------------------------------------------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 3 | +| 3.1 | Terms defined elsewhere ..... | 3 | +| 3.2 | Terms defined in this Recommendation ..... | 3 | +| 4 | Abbreviations and acronyms ..... | 3 | +| 5 | Conventions ..... | 6 | +| 6 | Brief introduction on Voice over LTE and assumptions ..... | 6 | +| 7 | Hypothetical reference models ..... | 9 | +| 7.1 | LTE-LTE communication on the same network ..... | 10 | +| 7.2 | LTE-LTE communication between two interconnected networks
(includes roaming) ..... | 11 | +| 7.3 | LTE-3G communication..... | 11 | +| 7.4 | LTE-PSTN communication ..... | 12 | +| 8 | Aspects of quality of service for voice over LTE services ..... | 12 | +| 9 | Relevant indicators and quality targets ..... | 14 | +| 10 | Recommendations for QoS monitoring and troubleshooting ..... | 21 | +| 10.1 | Recommended QoS monitoring points ..... | 21 | +| 10.2 | Monitoring strategy ..... | 26 | +| 10.3 | Available tools in ITU-T standards ..... | 29 | +| | Annex A – List of degradations encountered by end-users of VoLTE service and their
potential causes ..... | 33 | +| A.1 | QoS problem linked to call session performance ..... | 33 | +| A.2 | QoS problem linked to perceived speech quality ..... | 34 | +| | Bibliography..... | 36 | + + + +## Recommendation ITU-T G.1028 + +## End-to-end quality of service for voice over 4G mobile networks + +# 1 Scope + +This Recommendation works on the assumption that Voice over LTE (VoLTE) is a so-called "managed" voice service, in opposition to over the top (OTT) applications without use of session initiation protocol/IP multimedia subsystem (SIP/IMS) signalling and with no prioritized traffic. Video-telephony over LTE (ViLTE) is another service which is addressed in the specific Recommendation [ITU-T G.1028.2]. + +This Recommendation describes the key aspects impacting end-to-end performance of managed voice applications over LTE networks, for the most common call cases including circuit switched fall back (IMS tromboning is not considered, nor single radio voice call continuity (SRVCC), nor mobility under wireless local access network), and how they can be properly assessed using current elements of knowledge. + +Relevant quality of service (QoS) mechanisms used to manage the voice service, such as robust header compression (RoHC), transmission time interval (TTI) bundling, semi-persistent scheduling (SPS), discontinuous transmission (DTX) and reception (DRX), service domain selection (SDS) or SIP preconditions, are not considered in this Recommendation as a mandatory part of a VoLTE service, but their impact on end-to-end perceived quality will be taken into account. + +Analysis of the impact of VoLTE on quality of supplementary services (such as data streaming) or on device features (battery life) is outside the scope of this Recommendation. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T E.800] Recommendation ITU-T E.800 (2008), *Definitions of terms related to quality of services*. +- [ITU-T E.804] Recommendation ITU-T E.804 (2014), *Quality of service aspects for popular services in mobile networks*. +- [ITU-T G.107] Recommendation ITU-T G.107 (2015), *The E-model: a computational model for use in transmission planning*. +- [ITU-T G.107.1] Recommendation ITU-T G.107.1 (2015), *Wideband E-model* +- [ITU-T G.109] Recommendation ITU-T G.109 (1999), *Definition of categories of speech transmission quality*. +- [ITU-T G.114] Recommendation ITU-T G.114 (2003), *One-way transmission time* +- [ITU-T G.711] Recommendation ITU-T G.711 (1988), *Pulse code modulation (PCM) of voice frequencies*. +- [ITU-T G.1000] Recommendation ITU-T G.1000 (2001), *Communications quality of service: A framework and definitions*. + +- [ITU-T G.1028.1] Recommendation ITU-T G.1028.1 (2019), *End-to-end quality of service for video telephony over 4G mobile networks.* +- [ITU-T G.1028.2] Recommendation ITU-T G.1028.2 (2019), *Assessment of the LTE circuit switched fall back – impact on voice quality of service.* +- [ITU-T P.10] Recommendation ITU-T P.10/G.100 (2017), *Vocabulary for performance, quality of service and quality of experience.* +- [ITU-T P.563] Recommendation ITU-T P.563 (2004), *Single-ended method for objective speech quality assessment in narrow-band telephony applications.* +- [ITU-T P.564] Recommendation ITU-T P.564 (2007), *Conformance testing for voice over IP transmission quality assessment models.* +- [ITU-T P.800.1] Recommendation ITU-T P.800.1 (2016), *Mean opinion score (MOS) terminology.* +- [ITU-T P.862] Recommendation ITU-T P.862 (2001), *Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs.* +- [ITU-T P.863] Recommendation ITU-T P.863 (2018), *Perceptual objective listening quality prediction.* +- [ITU-T P.863.1] Recommendation ITU-T P.863.1 (2019), *Application guide for Recommendation ITU-T P.863.* +- [ITU-T Y.1540] Recommendation ITU-T Y.1540 (2016), *Internet protocol data communication service – IP packet transfer and availability performance parameters.* +- [ITU-T Y.1541] Recommendation ITU-T Y.1541 (2011), *Network performance objectives for IP-based services.* +- [ETSI TS 122 105] ETSI TS 122 105 v15.0.0 (2018), *Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Services and service capabilities.* +- [ETSI TS 123 203] ETSI TS 123 203 v 15.4.0 (2018), *Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; Policy and charging control architecture.* +- [ETSI TS 124 229] ETSI TS 124 229 v 15.6.0 (2019), *Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3.* +- [ETSI TS 126 114] ETSI TS 126 114 v 15.5.0 (2019), *Universal Mobile Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Multimedia telephony; Media handling and interaction.* +- [ETSI TS 126 131] ETSI TS 126 131 v 15.1.0 (2018), *Universal Mobile Telecommunications System (UMTS); LTE; Terminal acoustic characteristics for telephony; Requirements.* +- [ETSI TS 101 563] ETSI TS 101 563 v 1.4.1 (2015), *Speech and multimedia Transmission Quality (STQ); IMS/PES/VoLTE exchange performance requirements.* +- [ETSI TR 102 775] ETSI TR 102 775 v 1.6.3 (2014), *Speech and multimedia Transmission Quality (STQ); Guidance on objectives for Quality related Parameters at VoIP Segment-Connection Points; A support to NGN transmission planners.* + +- [ETSI TR 103 219] ETSI TR 103 219 v1.1.1 (2015), *Speech and multimedia Transmission Quality (STQ); Quality of Service aspects of voice communication in an LTE environment.* +- [ETSI TR 125 912] ETSI TR 102 912 v 15.0.0 (2018), *Universal Mobile Telecommunications System (UMTS); LTE; Feasibility study for evolved Universal Terrestrial Radio Access (UTRA) and Universal Terrestrial Radio Access Network (UTRAN).* +- [IETF RFC 6076] IETF RFC 6076 (2011), *Basic Telephony SIP End-to-End Performance Metrics.* +- [IETF RFC 3095] IETF RFC 3095 (2001), *Robust Header Compression (RoHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed.* + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 call set-up time** [ITU-T E.800]: The period starting when the address information required for setting up a call is received by the network (recognized on the calling user's access line) and finishing when the called party busy tone, or ringing tone or answer signal is received by the calling party (i.e., recognized on the calling user's access line). Local, national and service calls should be included, but calls to Other Licensed Operators should not, as a given operator cannot control the QoS delivered by another network. +- 3.1.2 speech quality** [ITU-T P.10]: Quality of spoken language as perceived when acoustically displayed. Result of a perception and assessment process, in which the assessing subject establishes a relationship between the perceived characteristics, i.e., the auditory event, and the desired or expected characteristics. +- 3.1.3 service accessibility performance** [ITU-T E.800]: The ability of a service to be obtained, within specified tolerances and other given conditions, when requested by the user. +- 3.1.4 mean one-way propagation time** [ITU-T P.10]: In a connection, the mean of the propagation times in the two directions of transmission. + +## 3.2 Terms defined in this Recommendation + +None. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-----|-------------------------------------------------------------| +| 2G | Second Generation of radio access network (also called GSM) | +| 3G | Third Generation of radio access network (also called UMTS) | +| 4G | Fourth Generation of radio access network (also called LTE) | +| ACK | Acknowledgment | +| AEC | Acoustical Echo Cancellation | +| AF | Application Function | +| AGC | Automatic Gain Control | +| AGW | Access Gateway | + +| | | +|----------|----------------------------------------------------------| +| AMR | Adaptive Multi Rate coding | +| AMR-WB | Wide-Band Adaptive Multi Rate coding | +| BGCF | Border Gateway Control Function | +| BTS | Base Transceiver Station | +| CDR | Call Detail Record | +| CNG | Comfort Noise Generation | +| CS | Circuit Switched | +| CSFB | Circuit Switched Fall Back | +| DL | Downlink | +| DRX | Discontinuous Reception | +| DTX | Discontinuous Transmission | +| EEC | Electrical Echo Cancellation | +| E-NodeB | Enhanced Node B | +| EPC | Evolved Packet Core | +| E-UTRAN | Evolved UMTS Terrestrial Radio Access Network | +| EVS | Enhanced Voice Services | +| GBR | Guaranteed Bit Rate | +| GERAN | GSM/Edge Radio Access Network | +| GGSN | Gateway GPRS (General Packet Radio Service) Service Node | +| GSM | Global System for Mobile Communications | +| GSMA | The GSM Association | +| GW | Gateway | +| HARQ | Hybrid Automatic-Repeat-Request | +| HD voice | High Definition voice | +| HO | Hand Over | +| HSS | Home Subscriber Server | +| I-CSCF | Interrogating Call Session Control Function | +| IMS | IP Multimedia Subsystem | +| IPDV | Internet Packet Delay Variation | +| IPER | Internet Packet Error Ratio | +| IPLR | Internet Packet Loss Ratio | +| IPTD | Internet Packet Transfer Delay | +| IRA | Ineffective Registration Attempt | +| KPI | Key Performance Indicator | +| LTE | Long Term Evolution (of radio access networks) | +| MGCF | Media Gateway Controller Function | +| MGW | Media Gateway | + +| | | +|--------|----------------------------------------------------------| +| MME | Mobility Management Entity | +| MOS | Mean Opinion Score | +| MOS-LQ | Mean Opinion Score – Listening Quality | +| MTAS | Multimedia Telephony Application Server | +| MTSI | Multimedia Telephony Service for IMS | +| NB | Narrow Band (voice spectrum) | +| NER | Network Error Rate | +| O-SDS | Originating Service Domain Selection | +| OTT | Over-The-Top | +| PCC | Policy and Charging Control | +| PCEF | Policy and Charging Enforcement Function | +| PCRF | Policy and Charging Rule Function | +| P-CSCF | Proxy Call Session Control Function | +| PDD | Post Dialling Delay | +| PGW | Packet Data Network Gateway | +| PLC | Packet Loss Concealment | +| PLMN | Public Land Mobile Network | +| PSTN | Public Switched Telephone Network | +| QCI | Quality Classification Identifier | +| QoS | Quality of Service | +| RACH | Random Access Channel | +| RoHC | Robust Header Compression | +| RRC | Radio Resource Control | +| RTCP | Real-time Transport Control Protocol | +| RTP | Real-time Transport Protocol | +| S-CSCF | Serving Call Session Control Function | +| SCR | Session Completion Ratio | +| SDP | Session Description Protocol | +| SDS | Service Domain Selection | +| SEER | Session Establishment Effectiveness Ratio | +| SGSN | Service GPRS (General Packet Radio Service) Support Node | +| SGW | Serving Gateway | +| SIP | Session Initiation Protocol | +| SIP-I | Session Initiation Protocol with encapsulated ISUP | +| SPR | Subscriber Profile Repository | +| SPS | Semi-Persistent Scheduling | +| SRD | Session Request Delay | + +| | | +|--------|-------------------------------------------| +| SRVCC | Single Radio Voice Call Continuity | +| SWB | Super Wide Band (voice spectrum) | +| T-ADS | Terminating Access Domain Selection | +| TDM | Time Domain Multiplication | +| TrFO | Transcoding Free Operation | +| TrGW | Trunking Gateway | +| T-SDS | Terminating Service Domain Selection | +| TTI | Transmission Time Interval | +| UDP | User Datagram Protocol | +| UE | User's Equipment | +| UL | Uplink | +| UMTS | Universal Mobile Telecommunication System | +| UTRAN | UMTS Terrestrial Radio Access Network | +| VAD | Voice Activity Detection | +| ViLTE | Video-telephony over LTE | +| VoWiFi | Voice over WiFi | +| VoLTE | Voice over LTE | +| VQE | Voice Quality Enhancement | +| WB | Wide Band (voice spectrum) | +| WiFi | Wireless Fidelity radio access network | + +# 5 Conventions + +None. + +# 6 Brief introduction on Voice over LTE and assumptions + +This Recommendation makes the following assumptions, in line with the IMS profile for voice defined by the global system for mobile communications association (GSMA) in [b-GSMA IR.92] and the multimedia telephony service for IMS (MTSI) media handling procedures (voice part only) defined by 3GPP in [ETSI TS 126 114], as far as Voice over LTE (VoLTE) is concerned: + +- Voice calls are initiated and/or received by a terminal connected to a 4G radio access network (evolved universal terrestrial radio access network, or E-UTRAN). +- Terminals connected to E-UTRAN embed a VoLTE client by default, either directly native on the chip or as a dedicated application. +- E-UTRAN is connected to an evolved packet core (EPC) network. The connecting point is an enhanced node B (e-NodeB). +- EPC enables the communication between 4G terminals and IMS core platforms, in order to set up calls using the session initiation protocol (SIP). There is no other possibility to set up calls. +- EPC supports quality of service (QoS) classification (between policy and charging enforcement function (PCEF) and the terminal), as defined in [ETSI TS 122 105] (section 5) and [ETSI TS 123 203] (section 6.1.7 and associated table partially reproduced in Table 1). + +- SIP signalling is assigned with the QoS quality classification identifier (QCI) 5. +- Real time voice signal during calls is carried out with the real-time transport protocol/user datagram protocol (RTP/UDP), and is assigned with the QCI 1. +- The application of QCI 5 for SIP signalling bearer and QCI 1 for real time voice bearer gives them a high priority over all data bearer, resulting in no degradation of the voice service when used in parallel with data session on the same device. +- Voice calls are possible seamless with any far end user of circuit switched (CS) voice connected to public switched telephone network (PSTN) or to 2G or 3G mobile access. This implies that the VoLTE service is assumed being deployed over the entire 4G network. Cases of VoLTE terminals being under 4G but non-VoLTE coverage are not considered. +- Voice calls between two VoLTE clients can be placed using any bit rate and codec mode of adaptive multi rate coding (AMR) and wide-band adaptive multi rate coding (AMR-WB), as indicated in section 3.2.1 of [b-GSMA IR.92]. In the near future, the super wide band (SWB) codec enhanced voice services (EVS) will also be supported. Entities ending the user plane (terminal, media gateways (MGWs)) support transcoding free operation (TrFO). +- The feature TrFO on SIP session initiation protocol with encapsulated ISUP (SIP-I) is activated which means that codec negotiation between VoLTE and the other networks is performed in an end-to-end way. + +**Table 1 – Quality classification identifiers in use for voice over LTE +(source: [ETSI TS 123 203])** + +| QCI | Resource type | Priority level | Packet delay budget | Packet error loss rate | Example services | +|-----|---------------|----------------|---------------------|------------------------|----------------------| +| 1 | GBR | 2 | 100 ms (Note) | $10^{-2}$ | Conversational voice | +| 5 | Non-GBR | 1 | 100 ms (Note) | $10^{-6}$ | IMS signalling | + +NOTE – A delay of 20 ms for the delay between a PCEF and a radio base station should be subtracted from a given packet delay budget to derive the packet delay budget that applies to the radio interface. This delay is the average between the case where the PCEF is located "close" to the radio base station (roughly 10 ms) and the case where the PCEF is located "far" from the radio base station, e.g., in case of roaming with home routed traffic (the one-way packet delay between Europe and North America west coast is roughly 50 ms). The average takes into account that roaming is a less typical scenario. It is expected that subtracting this average delay of 20 ms from a given packet delay budget will lead to desired end-to-end performance in most typical cases. Also, note that the packet delay budget defines an upper bound. Actual packet delays – in particular for guaranteed bit rate (GBR) traffic – should typically be lower than the packet delay budget specified for a QCI as long as the terminal has sufficient radio channel quality. + +These elements are constitutive of a so-called "managed" voice service, in opposition to OTT applications without use of SIP/IMS signalling and with no prioritized traffic. + +The two last characteristics of QCIs in Table 1 (packet delay budget, packet loss budget) seem to provide QoS targets, potentially in conflict to those proposed in Tables 4 to 7. In reality, as indicated in the Note below Table 1, these budgets are meant only for signalling messages exchanged between the radio access network and the IMS platform (and in particular the PCEF, i.e., mostly for charging procedures). + +Table 2 shows some realistic maximum values for packet delay budget on radio access for the user plane of VoLTE, as measured on some operational networks for mobile to mobile 4G calls on the same network, reproduced from [ETSI TR 102 775] (see Table A.13 and Table A.14) and [ETSI TR 125 912] (see Table 13.4). + +**Table 2 – Packet delay budget for user plane on 4G access network (4G-4G call)** + +| Step | Description | DL direction | UL direction | +|------|-----------------------------------------------------|------------------------|------------------------| +| 1 | eNB Processing Delay (S1-U->Uu) | 1 ms | 1 ms | +| 2 | Frame Alignment | 1.022 ms | 1.423 ms | +| 3 | TTI for DATA PACKET | 0.675 ms | 0.675 ms | +| 4 | HARQ Retransmission | 5 ms x HARQ proportion | 5 ms x HARQ proportion | +| 5 | UE Processing Delay | 1 ms | 1 ms | +| 6 | S1-U Transfer Delay and aGW | 7 ms | 15 ms | +| | Total one way delay (example with 30 % HARQ) | 12.2 ms | 20.6 ms | + +In cases when one of the critical elements above (VoLTE compatible terminal, IMS platform) is not available, then the call will be handled following the circuit switched fall back (CSFB) procedure (see clause 7). In what follows, whenever a provision of this Recommendation is applicable in both VoLTE and CSFB use cases, it will be mentioned explicitly. Whenever it is not applicable but relevant information is provided in [ITU-T G.1028.2], an explicit reference to this Recommendation will be indicated. + +Relevant QoS mechanisms used in 4G access network or in EPC and IMS platforms to manage the voice service are not considered in this Recommendation as a mandatory part of a VoLTE service, but their impact on end-to-end perceived quality will be taken into account as far as possible. The most frequent of these features are: + +- Robust header compression (RoHC, see [IETF RFC 3095]) is a method to shorten the size of voice packets (header often represents 60% of the total of a packet, and can be reduced by a factor of up to 20 thanks to RoHC) and thus limit the network bandwidth occupation. +- Transmission time interval (TTI) bundling is a mechanism to improve coverage at 4G cell edge or in poor radio conditions, by transmitting each packet four times in a row (without signalling overhead). +- Semi-persistent scheduling simplifies the allocation and re-allocation of radio resources in a cell and thus can allow more simultaneous VoLTE calls and a lower consumption of battery in devices. +- Discontinuous transmission (DTX) is a technique to reduce the bandwidth occupied by a voice call, by not transmitting data during silent periods. +- Discontinuous reception (DRX) puts the terminal into periodic repetition of sleep mode and wake up mode (to listen to messages from the network), allowing saving battery consumption. +- SIP preconditions, as specified in section 2.4.1 of [b-GSMA IR.92] and [ETSI TS 124 229], can be added to session description protocol (SDP) messages exchanged between terminals and IMS in order to ensure that the dedicated radio bearers are available before setting up the call. This strengthens the call set-up process but makes it longer by up to several seconds. +- Terminating or originating service domain selection (T-SDS and O-SDS) allows selecting between the CS or the IMS domain to provide the voice service to a VoLTE terminal under VoLTE and CS network coverage. The mechanism for the selection of domain to communicate call termination from the network to the terminal is called terminating access domain selection (T-ADS). + +# 7 Hypothetical reference models + +The global architecture supporting VoLTE services can be seen in Figure 1: + +![Overall architecture of VoLTE services diagram showing Device, Radio access, Mobile core, and Mobile IMS layers with various network components and interfaces.](724c7777b608e53be38b12b6fb3c43bc_img.jpg) + +The diagram illustrates the overall architecture of VoLTE services, organized into four main horizontal layers: Device, Radio access, Mobile core, and Mobile IMS. + +- Device:** Contains the LTE-UU (User Equipment) with layers for PDCP, RLC, DRB (Data Radio Bearer), UM (Unacknowledged Mode), AM (Acknowledged Mode), SRB2, SRB1, and SRB0. It also shows protocols like RTP, SIP/SDP, and RRC. +- Radio access:** Includes the eNodeB connected to the LTE-UU via S1-U. It also shows the GERAN (GPRS) and UTRAN (UMTS) access networks with components like BTS, BSC/RNC, NodeB, and RNC. The NGN (Next Generation Network) is also shown. +- Mobile core:** Features the S-GW (Serving Gateway) and P-GW (PDN Gateway) connected via S1-MME and S11 interfaces. The MME (Mobility Management Entity) is connected to the P-GW via S5 and S11 interfaces. The HSS (Home Subscriber Server) is connected to the MME via S6a and to the P-GW via S5. The P-CSCF (PDN Connectivity Session Management Function) is connected to the P-GW via S5 and to the SPR (Service Profile Repository) via S6a. The P-CEF (PDN Connectivity Session Management Function) is connected to the P-CSCF via S5 and to the SPR via S6a. The BGCF (Bibliography Gateway) is connected to the P-CSCF via S5 and to the SPR via S6a. +- Mobile IMS:** Contains the SRVCC (Single Radio Voice Call Continuity) component, which includes the ATGW (ATGW), ATCF (ATCF), SCC-AS (SCC-AS), ASs (ASs), TAS (TAS), and voicemail. The MRFP (Media Resource Function Processor) and MRFC (Media Resource Function Controller) are also shown. The IMS is connected to the P-CSCF via S5 and to the SPR via S6a. + +External connections include: + +- GERAN (GPRS):** Connected to the BSC/RNC. +- UTRAN (UMTS):** Connected to the NodeB and RNC. +- NGN:** Connected to the BSC/RNC and the eMSC. +- OT (Other Networks):** Connected to the IBCF and TrGW. +- PSTN:** Connected to the MGCF and MGW. +- Broadband IMS:** Connected to the MGCF and MGW. + +Overall architecture of VoLTE services diagram showing Device, Radio access, Mobile core, and Mobile IMS layers with various network components and interfaces. + +G.1028(16)\_F01 + +**Figure 1 – Overall architecture of VoLTE services** + +Several blocks are present and form the basic elements of a reference model: + +- The terminal +- The E-UTRAN +- The EPC network +- The mobile IMS core network +- Other radio access networks (GERAN and UTRAN) +- Mobile core networks for 2G and 3G +- Interconnection with other EPC or fixed networks + +The description above is simplified in Figure 2: + +![Figure 2 – Simplified architecture of VoLTE services. The diagram shows a linear flow from left to right: Terminal (UE) connected to E-UTRAN, which is connected to EPC, which is connected to Mobile IMS. Mobile IMS is connected to Interconnection. Above Mobile IMS, there is a box labeled 'Other mobile CN' which is connected to two boxes: 'GERAN + far-end UE (2G)' and 'UTRAN + far-end UE (3G)'. The text 'G.1028(16)_F02' is in the bottom right corner.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +``` + +graph LR + UE[Terminal (UE)] --- EUTRAN[E-UTRAN] + EUTRAN --- EPC[EPC] + EPC --- IMS[Mobile IMS] + IMS --- Interconnection[Interconnection] + IMS --- OtherCN[Other mobile CN] + OtherCN --- GERAN[GERAN + far-end UE (2G)] + OtherCN --- UTRAN[UTRAN + far-end UE (3G)] + +``` + +Figure 2 – Simplified architecture of VoLTE services. The diagram shows a linear flow from left to right: Terminal (UE) connected to E-UTRAN, which is connected to EPC, which is connected to Mobile IMS. Mobile IMS is connected to Interconnection. Above Mobile IMS, there is a box labeled 'Other mobile CN' which is connected to two boxes: 'GERAN + far-end UE (2G)' and 'UTRAN + far-end UE (3G)'. The text 'G.1028(16)\_F02' is in the bottom right corner. + +**Figure 2 – Simplified architecture of VoLTE services** + +This Recommendation provides an overview of the impact of various issues on perceived quality, together with an estimation of the quantization of this impact by building block of the hypothetical reference model, for several end-to-end scenarios falling into the scope of this Recommendation. + +A client of a VoLTE service can experience different types of calls: + +- Basic call: Either with another VoLTE user connected to the same 4G network (see clause 7.1) or with a user of another voice network (CS or PSTN, see clauses 7.3 and 7.4). +- Circuit switched fall back (CSFB): A call with another 4G terminal, when one of the two ends must perform a fall back to a CS connection over 3G or 2G before call set up. From a user point of view, CSFB is automatic and transparent, no action is required. The performance of CSFB in terms of call set up is seen as a sub-part of basic call performance and is addressed specifically in Recommendation ITU-T G.1028.2. Once the CSFB is performed, the performance objectives in terms of integrity and call retainability are similar to the ones of a basic call (see clauses 7.3 and 7.4). +- Interconnection: A call between two VoLTE terminals connected to two different interconnected networks (see clause 7.2). +- IMS tromboning: When the VoLTE terminal is under CS coverage, signalling and user planes go through the IMS domain. From the e2e performance perspective, this IMS tromboning should only impact end-to-end delay and post dialling delay (PDD). This call case is outside the scope of the present Recommendation. + +Due to mobility, a call initiated under a 4G VoLTE coverage may have to hand over (HO) to CS coverage in order to continue. This process, known as SRVCC, is also outside of the current scope of this Recommendation and under consideration for a further revision. + +A call initiated under a 4G VoLTE coverage may also have to hand over to wireless local access network coverage. A 4G terminal may also directly start a voice call on an IMS platform under this radio coverage. This use case, known as voice over WiFi (VoWiFi), is also outside of the current scope of this Recommendation and under consideration for a further revision. + +The most common scenarios, considered in this Recommendation, are detailed below. + +## 7.1 LTE-LTE communication on the same network + +As shown in Figure 3, two clients of the same VoLTE service are in communication. It is assumed that they are not located under the coverage of the same cell. + +![Figure 3: Hypothetical reference model for an LTE-LTE communication on the same network. The diagram shows two 'Terminal (UE)' blocks, each connected to an 'E-UTRAN' block. Both 'E-UTRAN' blocks are connected to a single 'EPC' block. The 'EPC' block is connected to a 'Mobile IMS' block. The label 'G.1028(16)_F03' is at the bottom right.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +Figure 3: Hypothetical reference model for an LTE-LTE communication on the same network. The diagram shows two 'Terminal (UE)' blocks, each connected to an 'E-UTRAN' block. Both 'E-UTRAN' blocks are connected to a single 'EPC' block. The 'EPC' block is connected to a 'Mobile IMS' block. The label 'G.1028(16)\_F03' is at the bottom right. + +**Figure 3 – Hypothetical reference model for an LTE-LTE communication on the same network** + +## 7.2 LTE-LTE communication between two interconnected networks (includes roaming) + +Figure 4 shows clients of VoLTE services of two different operators in communication. The IMS core networks are interconnected, allowing both signalling and user plane continuity. + +It is assumed that this interconnection is IP-based (time domain multiplication (TDM)) solution is not considered). Also TrFO on SIP SIP-I feature is assumed activated on both networks. + +![Figure 4: Hypothetical reference model for an LTE-LTE communication between two interconnected networks. The diagram shows two identical network stacks. The top stack consists of 'Terminal (UE)' -> 'E-UTRAN' -> 'EPC' -> 'Mobile IMS'. The bottom stack consists of 'Terminal (UE)' -> 'E-UTRAN' -> 'EPC' -> 'Mobile IMS'. The 'Mobile IMS' blocks of both stacks are connected to a common 'Interconnection' block. The label 'G.1028(16)_F04' is at the bottom right.](33a8f3f01dfa8bce75d23017855a13c5_img.jpg) + +Figure 4: Hypothetical reference model for an LTE-LTE communication between two interconnected networks. The diagram shows two identical network stacks. The top stack consists of 'Terminal (UE)' -> 'E-UTRAN' -> 'EPC' -> 'Mobile IMS'. The bottom stack consists of 'Terminal (UE)' -> 'E-UTRAN' -> 'EPC' -> 'Mobile IMS'. The 'Mobile IMS' blocks of both stacks are connected to a common 'Interconnection' block. The label 'G.1028(16)\_F04' is at the bottom right. + +**Figure 4 – Hypothetical reference model for an LTE-LTE communication between two interconnected networks** + +Two different VoLTE interconnections cases can be addressed: + +- The two networks are directly interconnected which yields the use of the same codec – as for intra public land mobile network (PLMN) case – and low values of PDD and end-to-end delay. +- The two networks are interconnected through a CS intermediate network that increases PDD and end-to-end delay, reduces the codec rate, and might even cause the loss of high definition voice (HD voice) (if WB AMR codec is not supported by the CS network). + +## 7.3 LTE-3G communication + +When a VoLTE client is in communication with a CS mobile client, the mobile IMS is connected to the 3G mobile core network (see Figure 5), allowing both signalling and user plane continuity. + +![Figure 5: Hypothetical reference model for an LTE-3G communication. The top stack consists of 'Terminal (UE)' -> 'UTRAN' -> '3Gmobile CN'. The bottom stack consists of 'Terminal (UE)' -> 'E-UTRAN' -> 'EPC' -> 'Mobile IMS'. The '3Gmobile CN' block and the 'Mobile IMS' block are connected to each other. The label 'G.1028(16)_F05' is at the bottom right.](b0d4609bc46c2d88a8318706bb5321f7_img.jpg) + +Figure 5: Hypothetical reference model for an LTE-3G communication. The top stack consists of 'Terminal (UE)' -> 'UTRAN' -> '3Gmobile CN'. The bottom stack consists of 'Terminal (UE)' -> 'E-UTRAN' -> 'EPC' -> 'Mobile IMS'. The '3Gmobile CN' block and the 'Mobile IMS' block are connected to each other. The label 'G.1028(16)\_F05' is at the bottom right. + +**Figure 5 – Hypothetical reference model for an LTE-3G communication** + +## 7.4 LTE-PSTN communication + +When a VoLTE client is in communication with a user on PSTN, the mobile IMS is connected to the fixed IMS (see Figure 6), allowing both signalling and user plane continuity. + +![Figure 6: Hypothetical reference model for an LTE-PSTN communication. The diagram shows a sequence of components: Terminal (UE) connected to E-UTRAN, which is connected to EPC, which is connected to Mobile IMS. The Mobile IMS is connected to an Interconnection block, which is connected to Fixed IMS, which is connected to PSTN. The diagram is labeled G.1028(16)_F06.](dfe556fea00682b09a59427aaf72051c_img.jpg) + +``` +graph LR; UE[Terminal (UE)] --- EUTRAN[E-UTRAN]; EUTRAN --- EPC[EPC]; EPC --- MobileIMS[Mobile IMS]; MobileIMS --- Interconnection[Interconnection]; Interconnection --- FixedIMS[Fixed IMS]; FixedIMS --- PSTN[PSTN]; +``` + +G.1028(16)\_F06 + +Figure 6: Hypothetical reference model for an LTE-PSTN communication. The diagram shows a sequence of components: Terminal (UE) connected to E-UTRAN, which is connected to EPC, which is connected to Mobile IMS. The Mobile IMS is connected to an Interconnection block, which is connected to Fixed IMS, which is connected to PSTN. The diagram is labeled G.1028(16)\_F06. + +**Figure 6 – Hypothetical reference model for an LTE-PSTN communication** + +All scenarios including interconnection to another network may include very long international paths. This is considered as a separate case and does not lead to considerations for the general budgeting of delays. + +# 8 Aspects of quality of service for voice over LTE services + +Figure 7 shows the QoS degradations that can be typically encountered on a VoLTE call. QoS is understood here as defined in [ITU-T E.800]. The main elements of the network are depicted to show the signalling and media elements as well as the connections with PSTN or mobile platforms. + +![Figure 7 – Typical degradations of VoLTE communications. A complex network diagram showing VoLTE traffic paths and associated quality degradation factors. At the top, an orange bar indicates 'E2E delay, E2E audio quality, availability of calls, PDD'. The diagram shows VoLTE traffic from user equipment (UE) through eUTRAN (eNodeB), SRVCC, and UTRAN GERAN to the EPC (MME, SGW, PGW). From the PGW, traffic goes to the IP Core network (AGW/CBGF) and then to the IMS (P-CSCF, I/S-CSCF, SCC-AS, AS, IMS, IBCF). The IMS connects to the PSTN (MGW, PSTN) and Fixed VoIP. Various degradation factors are listed in boxes around the network components. For example, at the UE, factors include Echo, Noise, Low/high audio level, Device acoustic, White calls, Chopped conversation, and Encoding/decoding issues. In the EPC, factors include Call drop, HandOver latency, and Radio degradations. In the IP Core network, factors include IP packet loss, Network delay variation (jitter), IP desequencing, Link failure, Unavailability of basic call, and Identification failure (SIM, etc.). In the IMS, factors include Unavailability, DTMF not recognised, and Encoding/decoding issues. In the PSTN, factors include Echo (A and E), Low/high audio level, Encoding/decoding issues, and Device acoustics. Other boxes mention IP packet loss (if IP), IP desequencing (if IP), Network delay variation (jitter), IP --> ATM loss, and Link failure. A box at the bottom right mentions 'Interworking PSTN/fixed VoIP/mobile'.](9c6461e1e94afae4dec455e69a2ce152_img.jpg) + +Figure 7 – Typical degradations of VoLTE communications. A complex network diagram showing VoLTE traffic paths and associated quality degradation factors. At the top, an orange bar indicates 'E2E delay, E2E audio quality, availability of calls, PDD'. The diagram shows VoLTE traffic from user equipment (UE) through eUTRAN (eNodeB), SRVCC, and UTRAN GERAN to the EPC (MME, SGW, PGW). From the PGW, traffic goes to the IP Core network (AGW/CBGF) and then to the IMS (P-CSCF, I/S-CSCF, SCC-AS, AS, IMS, IBCF). The IMS connects to the PSTN (MGW, PSTN) and Fixed VoIP. Various degradation factors are listed in boxes around the network components. For example, at the UE, factors include Echo, Noise, Low/high audio level, Device acoustic, White calls, Chopped conversation, and Encoding/decoding issues. In the EPC, factors include Call drop, HandOver latency, and Radio degradations. In the IP Core network, factors include IP packet loss, Network delay variation (jitter), IP desequencing, Link failure, Unavailability of basic call, and Identification failure (SIM, etc.). In the IMS, factors include Unavailability, DTMF not recognised, and Encoding/decoding issues. In the PSTN, factors include Echo (A and E), Low/high audio level, Encoding/decoding issues, and Device acoustics. Other boxes mention IP packet loss (if IP), IP desequencing (if IP), Network delay variation (jitter), IP --> ATM loss, and Link failure. A box at the bottom right mentions 'Interworking PSTN/fixed VoIP/mobile'. + +G.1028(16)\_F07 + +**Figure 7 – Typical degradations of VoLTE communications** + +From a customer point of view (QoS required and perceived, as defined in [ITU-T G.1000]), these degradations are divided into the following categories: + +- Call session performance + - Problems of registration to the service (IMS/SIP). + - Call set up issues (bad accessibility). + - Failed continuity (or retainability), including impact of mobility (radio hand-overs and SRVCC events). +- Perceived speech quality during the call (integrity) + - Frequency content. This refers to the speech spectrum of signals presented to end users (NB, WB or SWB) and its potential distortions. + - Interruptions. Concerns all events resulting in clipping of the speech signal during the conversation. + - End to end delay (impact on conversation interactivity) + - Presence of unwanted noises, from whatever origin. + +A more detailed list of typical degradations encountered by end-users of VoLTE service, together with potential causes, is provided in Annex A, completed for CSFB specific causes by clause 9 of [ITU-T G.1028.2]. + +VoLTE can also have an impact on other services or functionalities of the device. For instance: + +- data transfer performance is potentially influenced by the presence of VoLTE usage on the same cell; +- battery autonomy can become critical if the usage of a given application (here VoLTE) is consuming too much power. + +These aspects are however outside the scope of the present Recommendation. + +To report, monitor and troubleshoot these QoS issues experienced by customers, consistent measurements architecture must be set up with appropriate metrics. This is the purpose of following sections. + +# 9 Relevant indicators and quality targets + +From an end-to-end perspective, as perceived by an end-user located under a VoLTE compliant 4G network coverage and originating calls, the relevant indicators are given in the Table 3, together with the potential contributor network key performance indicator(s) (KPI(s)). + +**Table 3 – End-to-end quality indicators and corresponding network KPIs** + +| End-to-end indicators | Definition | IP network KPIs | +|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Registration success rate | Rate of successful registration attempts in the VoLTE service
Equivalent to IMS registration success ratio as defined in [ETSI TR 103 219]
This metric does not apply to CSFB | Registration success rate
KPI related to IMS and based on P-CSCF counters.
Equivalent to 1 – ineffective registration attempt (IRA) ratio, as defined in [IETF RFC 6076] | +| Service availability | End to end service availability in terms of capacity to establish calls from, and to, a VoLTE customer.
Equivalent to 1 – VoLTE session set-up failure ratio as defined in [ETSI TR 103 219]
Equivalent to 1 – telephony service non-accessibility as defined in [ITU-T E.804] (clause 7.3.6.1)
For CSFB, a specific metric is given in clause 7.1 of [ITU-T G.1028.2] | Network efficiency ratio
Measures the ability of network, from the service platform point of view, to deliver calls to the VoLTE customer
Based on SIP protocol, network error rate (NER) is equivalent to session establishment effectiveness ratio (SEER), as defined in [IETF RFC 6076] | + +**Table 3 – End-to-end quality indicators and corresponding network KPIs** + +| End-to-end indicators | Definition | IP network KPIs | +|----------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Post dialling delay | Time interval (in seconds) between the end of dialling by the caller and the reception back by him of the appropriate ringing tone or recorded announcement.
Equivalent to call set-up time, as defined in [ITU-T E.800]
Equivalent to telephony set-up time as defined in [ITU-T E.804] (clause 7.3.6.2)
This metric applies to CSFB, with some specificities provided in clause 7.2 of [ITU-T G.1028.2] | SIP session set-up time
Interval between sending INVITE message (with SDP) and ACK (180 or 200) message by the originating side.
Equivalent to successful session request delay (SRD), as defined in [IETF RFC 6076] | +| Voice quality (MOS-LQO) | Equivalent to speech quality as defined in [ITU-T P.10].
Models like those defined in [ITU-T P.862] and [ITU-T P.863] provide an objective view on the quality of the voice signal as it may be perceived by the customer.
Can be seen on a call basis or on a sample basis (see [ITU-T E.804] clauses 7.3.6.3 and 7.3.6.4)
This metric applies to CSFB | Network quality index
([ITU-T G.107], [ITU-T P.564])
IP Packet loss ratio (see definition of Internet packet loss ratio (IPLR) in [ITU-T Y.1540]) : several possible measurement points. | +| Mouth-to-ear delay | The time it takes for the speech signal to go from the mouth of the speaker to the ear of the listener
This metric applies to CSFB | IP packet transfer delay
(see definition of Internet packet transfer delay (IPTD) in [ITU-T Y.1540])
Round trip time
Corresponds approximately to twice the end-to-end delay
Can be measured based on RTCP protocol messages | +| Call drop rate | Service continuity in terms of capacity to maintain calls to their normal end.
Equivalent to telephony cut-off call ratio as defined in [ITU-T E.804] (clause 7.3.6.5)
This metric applies to CSFB | Session completion rate
KPI related to IMS and based on P-CSCF counters
Equivalent to session completion ratio (SCR), as defined in [IETF RFC 6076] | +| Speech bandwidth (NB, WB or SWB) | Measurement of the bandwidth used (normal NB or WB, or even partial and unwanted bandwidth limitation).
This metric applies to CSFB | Codec statistics
Information related to the selection of (AMR and AMR WB) codec and codec modes, as well as switch between them, accessible on SIP protocol messages. | + +It should be noted that the definition for post dialling delay in Table 3 is equivalent to those of other metrics defined elsewhere. The "equivalence" expressed here does not mean that post dialling delay and call setup time are two names for one unique metric. The only definition applicable for post + +dialling delay is the one provided in Table 3. Other metrics are only metrics "looking like" PDD, helpful to estimate PDD magnitude and variations. + +In Table 3, the IP KPI associated with post dialling delay (SIP session set up time) is defined with two possible end triggers: 180 Ringing or 200 OK. However, these two SIP messages have specific and different meanings. Below is guidance concerning their usage for the measurement of SIP session set up time: + +- From a user's point of view, the meaningful information is the ringing tone he can hear back in his phone. This ringing tone is generally triggered by reception of a 180 Ringing message. +- In roaming situations, some LTE networks are sending a 180 Ringing message to the calling user independent from the real status of the called user and network(in some networks the 180 Ringing can be sent independent from the preconditions status). The caller may hear a ring back tone when the call setup procedure has failed. Only the reception of a 200 OK after the 180 Ringing message can make sure that this is not the case. But this 200 OK message could arrive sometime after the caller's terminal is ringing, providing thus a overestimation of perceived PDD. + +Therefore, it is recommended: + +- to use the 180 Ringing message as trigger for the measurement of PDD as perceived by end users, with a strong restriction to the cases where one can be 100 % sure that the network does not send this message before the called party and network accept the call. +- to use the 200 OK message in all cases to measure IP session set up time and qualify a call setup when the preconditions are fulfilled, as well as trigger for the measurement of PDD as perceived by end users in all cases where the restriction above cannot be met. + +Measurement points in VoLTE session set-up and completion procedures have been captured in Figures 8 and 9. + +![Sequence diagram for VoLTE session set-up measurement flow. Lifelines: IMS client, Terminal, IMS core, MTAS. The process starts with 'User initiates session' at the IMS client, leading to 'Initiate session signal' to the Terminal. The Terminal sends 'SIP INVITE' to the IMS core, which is forwarded to the MTAS as 'SIP INVITE to terminating network'. The MTAS returns 'SIP 183 session progress', which is passed back through the IMS core and Terminal. The Terminal performs 'Resource reservation' and sends 'SIP PRACK' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (PRACK)', which is passed back through the IMS core and Terminal. The Terminal then sends 'SIP UPDATE' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (UPDATE)', which is passed back through the IMS core and Terminal. The MTAS also sends 'SIP 180 Ringing from terminating network', which is passed back through the IMS core and Terminal. The Terminal sends 'SIP 200 OK (INVITE)' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (INVITE)', which is passed back through the IMS core and Terminal. The Terminal sends 'Alerted signal' and 'Session setup notification' to the IMS client. The IMS client sends 'Callee alerted notification' and 'Session setup notification' to the user. Red annotations indicate measurement points: 'SIP handshake time (SIP PRACK to SIP 200 OK on PRACK)', 'Conversation start delay (SIP 200 OK on INVITE to first received RTP packet)', 'Session setup delay (SIP INVITE to SIP 180 Ringing)', and 'Session setup success +'.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +Session setup success + + Session setup failure triggered on reception of SIP status code 401, 403, 404, 405, 408, 415, 420, 480, 486, 488, 500, 501, 504, 600, 603, 604, or 606. + Also triggered on SIP request CANCEL and if 'SessionSetupFailureTimeout' TD internal timer expired (default 120s). + +Sequence diagram for VoLTE session set-up measurement flow. Lifelines: IMS client, Terminal, IMS core, MTAS. The process starts with 'User initiates session' at the IMS client, leading to 'Initiate session signal' to the Terminal. The Terminal sends 'SIP INVITE' to the IMS core, which is forwarded to the MTAS as 'SIP INVITE to terminating network'. The MTAS returns 'SIP 183 session progress', which is passed back through the IMS core and Terminal. The Terminal performs 'Resource reservation' and sends 'SIP PRACK' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (PRACK)', which is passed back through the IMS core and Terminal. The Terminal then sends 'SIP UPDATE' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (UPDATE)', which is passed back through the IMS core and Terminal. The MTAS also sends 'SIP 180 Ringing from terminating network', which is passed back through the IMS core and Terminal. The Terminal sends 'SIP 200 OK (INVITE)' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (INVITE)', which is passed back through the IMS core and Terminal. The Terminal sends 'Alerted signal' and 'Session setup notification' to the IMS client. The IMS client sends 'Callee alerted notification' and 'Session setup notification' to the user. Red annotations indicate measurement points: 'SIP handshake time (SIP PRACK to SIP 200 OK on PRACK)', 'Conversation start delay (SIP 200 OK on INVITE to first received RTP packet)', 'Session setup delay (SIP INVITE to SIP 180 Ringing)', and 'Session setup success +'. + +**Figure 8 – VoLTE session set-up measurement flow** + +![Sequence diagram for VoLTE session completion measurement flow. Lifelines: IMS client, Terminal, IMS core, MTAS. The process starts with 'User release session' at the IMS client, leading to 'Release session signal' to the Terminal. The Terminal sends 'SIP BYE' to the IMS core, which is forwarded to the MTAS as 'SIP BYE to terminating network'. The MTAS returns 'SIP 200 OK (BYE)', which is passed back through the IMS core and Terminal. The Terminal performs 'Release of resource' and sends 'SIP 200 OK (BYE)' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (BYE)', which is passed back through the IMS core and Terminal. The Terminal sends 'Session released signal' to the IMS client. The IMS client sends 'Release notification' to the user. Red annotations indicate measurement points: 'Session disconnect delay (SIP BYE to SIP 200 OK on BYE)' and 'Session completion success +'.](d734a6ea1b381280f043fcf70391b6db_img.jpg) + +Session completion success + + Session Completion Failure triggered if no RTP packet received during a period longer than 'SessionDropTimeout' TD internal timer (default 15s), OR triggered if no SIP Status Code 200 OK (BYE) request received within 'SessionHangupTimeout' TD internal timer (default 3s), OR triggered on reception of SIP Status Code 481 (BYE). + +Sequence diagram for VoLTE session completion measurement flow. Lifelines: IMS client, Terminal, IMS core, MTAS. The process starts with 'User release session' at the IMS client, leading to 'Release session signal' to the Terminal. The Terminal sends 'SIP BYE' to the IMS core, which is forwarded to the MTAS as 'SIP BYE to terminating network'. The MTAS returns 'SIP 200 OK (BYE)', which is passed back through the IMS core and Terminal. The Terminal performs 'Release of resource' and sends 'SIP 200 OK (BYE)' to the IMS core, which is forwarded to the MTAS. The MTAS returns 'SIP 200 OK (BYE)', which is passed back through the IMS core and Terminal. The Terminal sends 'Session released signal' to the IMS client. The IMS client sends 'Release notification' to the user. Red annotations indicate measurement points: 'Session disconnect delay (SIP BYE to SIP 200 OK on BYE)' and 'Session completion success +'. + +**Figure 9 – VoLTE session completion measurement flow** + +For most of the indicators in Table 3, a budget can be assigned to the various segments that compose end-to-end paths as seen in clause 6. Tables 4 to 7 provide indications of target values that can be reasonably reached on each of these segments for each of the hypothetical reference connections depicted in clause 7. The total budget is not necessarily the exact sum of all individual budgets. + +These targets are examples of realistic values that network operators may reach when using tools complying with up-to-date standards. For instance, the mean opinion scores (MOS) in Tables 4 to 7 are meant as average values when applying [ITU-T P.863] with the right reference sentence (i.e., complying with [ITU-T P.863.1]) and doing a small drive test with state-of-the art devices. For + +longer drive test, with e.g., hand over (HO) events, then these values may be seen as a maximum. For lab tests with clean stable environment, then this may be seen as minimum value. It should also be noted that this could change in the future with new devices and network set-ups. + +## LTE-LTE communication on the same network + +**Table 4 – Quality budgets for LTE-LTE communication on the same network** + +| End-to-end indicators | TOTAL budget | Terminal | E-UTRAN | EPC | Mobile IMS | Transmission network | +|---------------------------|--------------------------------------------------------|---------------------------------------------|-----------|-----------|------------|-------------------------------------------| +| Registration success rate | 99.9% | 99.9% | 99.9% | 100% | 99.9% | No target | +| Service availability | 99%
Note 1 | No target | No target | No target | No target | No target | +| Post dialling delay (PDD) | LTE-LTE:
3.5 s
(Note 2)
CSFB: 6 s
(Note 3) | No target | No target | No target | No target | No target | +| Voice quality (MOS-LQxSW) | 4
(Note 4) | No target | No target | No target | No target | No target | +| Mouth-to-ear delay | 400 ms
(Note 5) | 190 ms
(sending + receiving)
(Note 6) | 5 ms | 15 ms | 0 | 10 ms (may be bigger for large countries) | +| Call drop rate | 2 % | No target | No target | No target | No target | No target | + +NOTE 1 – Call processing performance objective according to [ETSI TS 101 563] is higher than 99.9%. + +NOTE 2 – [ETSI TS 101 563] recommends 5.9 s, with 95% of probability below 2.4 s. + +NOTE 3 – Only circuit switched fall back on mobile originating side is considered here. + +NOTE 4 – Assumes the use of AMR-WB at a 23.85 kbit rate. The use of other codecs and/or bit rates will result in other values. + +NOTE 5 – [ITU-T G.114] specifies a preferred maximum value at 150 ms, impossible to reach currently; some network operators are able to provide national calls with delays below 250 ms. + +NOTE 6 – According to [ETSI TS 126 131]. + +## **LTE-LTE communication between two interconnected networks (includes roaming)** + +**Table 5 – Quality budgets for LTE-LTE communication between +two interconnected networks** + +| End-to-end indicators | TOTAL budget | Terminal | E-UTRAN | EPC | Mobile IMS | (International) transmission network | +|---------------------------|-------------------------------------------------------|---------------------------------------------|---------------------|-----------|------------|----------------------------------------------| +| Registration success rate | 99.9% | 99.9% | 99.9% | 100% | 99.9% | No target | +| Service availability | 99% | No target | No target | No target | No target | No target | +| Post dialling delay (PDD) | LTE-LTE: 4 s
CSFB: 6 s
(Note 1) | No target | No target | No target | No target | No target | +| Voice quality (MOS-LQxSW) | 4 (if HD voice + TrFO)
(Note 2)
2.8 (otherwise) | No target | No target | No target | No target | No target | +| Mouth-to-ear delay | 400 ms
(Note 3) | 190 ms
(sending + receiving)
(Note 4) | 80 ms on both sides | 50 ms | 0 | see typical values in [b-GSMA IR.34] Table 7 | +| Call drop rate | 2 % | No target | No target | No target | No target | No target | + +NOTE 1 – Only circuit switched fall back on mobile originating side is considered here. + NOTE 2 – Assumes the use of AMR-WB at a 23.85 kbit rate. The use of other codecs and/or bit rates will result in other values. + NOTE 3 – [ITU-T G.114] specifies a preferred maximum value at 150 ms, impossible to reach currently; some network operators are able to provide national calls with delays below 250 ms. + NOTE 4 – According to [ETSI TS 126 131]. + +## **LTE-3G communication** + +**Table 6 – Quality budgets for LTE-3G communication** + +| End-to-end indicators | TOTAL budget | Terminal | E-UTRAN | EPC | Mobile IMS | (Inter-national) trans-mission network | Far end access network | Far end terminal | +|---------------------------|----------------------------------|-----------|-----------|-----------|------------|----------------------------------------|------------------------|------------------| +| Registration success rate | 99.9% | 99.9% | 99.9% | 100% | 99.9% | No target | No target | No target | +| Service availability | 98% | No target | No target | No target | No target | No target | No target | No target | +| Post dialling delay (PDD) | 4.5 s
CSFB: for further study | No target | No target | No target | No target | No target | No target | No target | + +**Table 6 – Quality budgets for LTE-3G communication** + +| End-to-end indicators | TOTAL budget | Terminal | E-UTRAN | EPC | Mobile IMS | (Inter-national) trans-mission network | Far end access network | Far end terminal | +|------------------------------|-------------------------------------------------------|----------------------------------------|----------------|------------|-------------------|-----------------------------------------------|-------------------------------|-------------------------| +| Voice quality (MOS-LQxSW) | 3.8 (if HD voice + TrFO)
2.8 (otherwise)
Note 1 | No target | No target | No target | No target | No target | No target | No target | +| Mouth-to-ear delay | 400 ms
Note 2 | 190 ms (sending + receiving)
Note 3 | 80 ms | 50 ms | 0 | see typical values in [b-GSMA IR.34] Table 7 | UTRAN: 90 | 0 | +| Call drop rate | 3 % | No target | No target | No target | No target | No target | No target | No target | + +NOTE 1 – Assumes the use of AMR-WB at a 12.65 kbit rate. The use of other codecs and/or bit rates will result in other values. +NOTE 2 – [ITU-T G.114] specifies a preferred maximum value at 150 ms, impossible to reach currently; some network operators are able to provide national calls with delays below 300 ms. +NOTE 3 – According to [ETSI TS 126 131]. + +## **LTE-PSTN communication** + +**Table 7 – Quality budgets for LTE-PSTN communication** + +| End-to-end indicators | TOTAL budget | Terminal | E-UTRAN | EPC | Mobile IMS | (International) transmission network | PSTN | +|------------------------------|--------------------------------|-----------------|----------------|------------|-------------------|---------------------------------------------|----------------| +| Registration success rate | 99.9% | 99.9% | 99.9% | 100% | 99.9% | No target | No target | +| Service availability | 99% | No target | No target | No target | No target | No target | 100 % | +| Post dialling delay (PDD) | 4 s
CSFB: for further study | No target | No target | No target | No target | No target | No target | +| Voice quality (MOS-LQxSW) | 3.1 (Note 1) | No target | No target | No target | No target | No target | No degradation | + +**Table 7 – Quality budgets for LTE-PSTN communication** + +| End-to-end indicators | TOTAL budget | Terminal | E-UTRAN | EPC | Mobile IMS | (International) transmission network | PSTN | +|-----------------------|-----------------|---------------------------------------|-----------|-----------|------------|----------------------------------------------|-------| +| Mouth-to-ear delay | 400 ms (Note 2) | 190 ms (sending + receiving) (Note 3) | 80 ms | 50 ms | 0 | see typical values in [b-GSMA IR.34] Table 7 | 10 ms | +| Call drop rate | 2% | No target | No target | No target | No target | No target | 0 % | + +NOTE 1 – Assumes the use of AMR at a 12.2 kbit rate. The use of other codecs and/or bit rates will result in other values. +NOTE 2 – [ITU-T G.114] specifies a preferred maximum value at 150 ms, impossible to reach currently; some network operators are able to provide national calls with delays below 250 ms. +NOTE 3 – According to [ETSI TS 126 131]. + +# 10 Recommendations for QoS monitoring and troubleshooting + +## 10.1 Recommended QoS monitoring points + +The measurement points are critical to locate the issues as economical and operational matters required to limit the number of probes, robots or other tools. + +The objective is to ensure a good representation of the covered territory in statistical terms for reporting, monitoring and troubleshooting with associated measurements sources or tools (probes, robots, counters and call detail records – CDRs). + +Three kinds of measurements points can be envisaged (see Figure 10 below): + +- At end points, where end-users access and experience the service (here A and J). +- At interfaces where the user plan is accessible, in general at demarcation points between network trunks or transmission technologies: here B, D, E and G. +- At points of presence of serving elements concerning signalling plan: here points C, F, and H (but also E). + +![Figure 10 – VoLTE QoS measurement points. This is a complex network architecture diagram showing various components and measurement points. On the left, three measurement points A1, A2, and A3 are shown at the user equipment (UE) level, connected to VoLTE services. The UE connects to eUTRAN (eNodeB) which is part of the EPC (Evolved Packet Core). The EPC includes an MME (Mobility Management Entity), SGW (Serving Gateway), and PGW (PDN Gateway). The MME is connected to the HSS (Home Subscriber Server) via the S6a interface. The PGW connects to an IP Core network. The IP Core network is connected to an AGW/CBGF (Access Gateway/Cellular Gateway), which is further connected to a PSTN MGW (Mobile Gateway). The PSTN MGW connects to the PSTN (Packet Switched Network). The IP Core network also connects to a Fixed VoIP network. The Fixed VoIP network is connected to a Call server, which is connected to an IBCF (Interconnection Border Control Function). The IBCF is connected to the PSTN via a TrGW (Trusted Gateway). The diagram also shows various interfaces: S1c, S1u, S11, S5/S8, S6a, S4, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50. Other measurement points are labeled: B (at eNodeB), C1, C2, C3, D1, D2, D3, E (at MGW), F (at HSS), G1, G2, H1, H2, H3, H4, I (at Call server), J (at PSTN MGW), and G3 (at TrGW). The diagram also includes labels for SRVCC, 2G/3G core, UTRAN GERAN, and Interconnections with PTO.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg) + +Figure 10 – VoLTE QoS measurement points. This is a complex network architecture diagram showing various components and measurement points. On the left, three measurement points A1, A2, and A3 are shown at the user equipment (UE) level, connected to VoLTE services. The UE connects to eUTRAN (eNodeB) which is part of the EPC (Evolved Packet Core). The EPC includes an MME (Mobility Management Entity), SGW (Serving Gateway), and PGW (PDN Gateway). The MME is connected to the HSS (Home Subscriber Server) via the S6a interface. The PGW connects to an IP Core network. The IP Core network is connected to an AGW/CBGF (Access Gateway/Cellular Gateway), which is further connected to a PSTN MGW (Mobile Gateway). The PSTN MGW connects to the PSTN (Packet Switched Network). The IP Core network also connects to a Fixed VoIP network. The Fixed VoIP network is connected to a Call server, which is connected to an IBCF (Interconnection Border Control Function). The IBCF is connected to the PSTN via a TrGW (Trusted Gateway). The diagram also shows various interfaces: S1c, S1u, S11, S5/S8, S6a, S4, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50. Other measurement points are labeled: B (at eNodeB), C1, C2, C3, D1, D2, D3, E (at MGW), F (at HSS), G1, G2, H1, H2, H3, H4, I (at Call server), J (at PSTN MGW), and G3 (at TrGW). The diagram also includes labels for SRVCC, 2G/3G core, UTRAN GERAN, and Interconnections with PTO. + +**Figure 10 – VoLTE QoS measurement points** + +### 10.1.1 Measurement points A1, A2 and A3 + +Measurement at the customer premises is absolutely necessary to answer the important need of knowledge on how the service quality is felt by end users. It gives a real end-to-end vision as there is no other place to obtain it. + +Then comes of course the question of representation: how many measurement points, what geographical repartition? The answer depends on the possible solutions at the concerned measurement points. + +Different implementation are possible: + +**A1** measurement point is intended for measurements from a reporting point of view (manual test campaigns). + +In fact, this point is not mandatory for supervision. But from an operator's point of view, a lot of QoS evaluations with this methodology are done each year on the entire network for regulatory or benchmark purposes. So, it is a way to check the QoS and to try to resolve encountered problems. + +It enables to test end-to-end metrics on accuracy mostly, but also availability, and continuity. Such methodology is generally based on: + +- A good and representative coverage of country area (rural, towns of different sizes, etc.). +- A selection of representative situation of communications (indoor, street, car, train, etc.). +- A selection of representative devices on the operator network. +- A selection of representative day periods to perform calls. +- A selection of representative calls. Narrowband and wideband calls must be taken into account. +- Enough measurements to have a correct view of QoS of the operator and relevant statistics. + +**A2** and **A3** measurement points are intended for measurements where tools replace the end user present in A1 and model his/her behaviour and quality judgment. They are recommended for reporting purposes, on end-to-end metrics on accuracy mostly, but also availability, continuity and service speed. This is where intrusive robots, drive test tools, radio tool analysers and soft agents are required. The cost of such solution stipulates that only a sampling strategy can be envisaged. The selection of measurement locations, devices and time periods follow similar criteria as for A1, but with less constraints since these are automatic tools. + +**A2** is inside the terminal. There soft agent can access decoded signal and/or information on how the communication is being processed (call set-up, call drop, IP jitter buffer behaviour, etc.). Such solutions are generally very cost-effective, can collect data on a very large panel of users and devices, but may require a participation or feedback of end-users. + +**A3** is where intrusive tools are required. This can be either static solutions based on robots (the focus will then be placed on service speed, accuracy and continuity) or mobile solutions (called drive test tools, with a larger focus enclosing also radio network performance). As seen before, for cost and operational reasons, only a sampling strategy can be envisaged with such tools (typically less than ten measurement points for national network). Moreover if a problem is reported by a measurement tool, it means that many users are probably impacted equally. As a consequence of the low number of measurements resulting from this sampling strategy, such tools will be mostly used for reporting purposes. Drive test tools are also commonly used for troubleshooting, when the enhancement of QoS is linked with the optimization of network coverage. + +It is important to understand that this end-to-end vision enables the detection or the confirmation of a problem but rarely to know the source of the degradation, unless it comes from the device. + +### **10.1.2 Measurement point B** + +The access part of the network is an important source of outages (biggest number of network elements). Therefore, its supervision is also necessary. One of the main difficulties is to take into account the radio part which can be clearly different according to the selected area. + +The **B** point is localized in eNodeB, which is the first ingress point to the LTE network. This measurement point assumes monitoring the interfaces on both radio and in the EPC direction. The strategy assumes differentiation of VoIP traffic from other data traffic based on adequate traffic class indicator (QCI). + +It is intended for measurements of: + +- radio performance in cells: It is recommended notably for troubleshooting purposes, on metrics on network performance. Together with A2, the eNodeB point should enable a correct view of radio coverage performances of area; +- signalling flows, to establish statistics about calls: It is highly recommended for reporting, monitoring and troubleshooting purposes on end-to-end metrics on service availability, continuity, accuracy, utilization and network performance. + +Supervision tools from RAN providers can enable a global aggregation of those kinds of information from all eNodeBs. + +The measurement strategy for this point should be rather cheap in implementation (i.e., performance counters accessible from the device) than exhaustive. + +### **10.1.3 Measurement points C1, C2 and C3** + +Points **C1** to **C3** corresponds to the interfaces of EPC (in fact all are localized close to mobility management entity (MME)) where most important signalling messages can be captured and analysed. They are recommended for reporting, monitoring and troubleshooting purposes on end-to-end metrics on service availability, continuity, and utilization. An exhaustive access to all data for all session is recommended, mostly through the usage of probes or network element call detail records (CDRs). + +**C1** covers signalling between MME and radio access (interface S1), **C2** supervises the link to serving GW (interface S11), whereas with **C3** the Sgs interface with MSC server is also addressed (this interface and S3, both corresponding to capture point C3, are the ones to be monitored for the assessment of CSFB procedures). + +Please note that the traffic captured on all interfaces covered by C points is tunnelled (GTP v2-C). + +These measurement point are important especially for the analysis of: + +- EPS bearer statistics. +- Mobility management (HO statistics, routing area update). +- Subscriber management (direct connection to HSS). + +### **10.1.4 Measurement points D1 and D2** + +Like C1, C2 and C3 these points are located inside the EPC, but covers interfaces where real time flows (using the RTP protocol) can be captured and analysed. + +**D1** is positioned at the egress between EPC and radio access (interface S1u of serving GW), whereas **D2** covers the link between serving and PDN GWs (interfaces S5-S8). + +The serving GW constitutes the anchor point for intra-LTE mobility, as well as for mobility between GSM/GPRS, 3G/HSPA and LTE. It supports transport level QoS through marking IP packets with appropriate DiffServ code points based on the parameters associated with the corresponding bearer. + +The PDN GW is the point of interconnect to external IP networks through the SGi interface. It also has a key role in supporting QoS for end-user IP services. + +With such critical measurement points, all information on the quality of transport of communication is accessible. They are highly recommended for reporting, monitoring and troubleshooting purposes on end-to-end metrics on service availability, continuity, accuracy, speed and network performance. An exhaustive access to all data for all session is recommended, mostly through the usage of probes or network element CDRs. + +### **10.1.5 Measurement point E** + +Measurement point **E** is located at the border between EPC and 3G core network. The corresponding equipment is the MSC server, which controls calls and mobility in 2G and 3G networks (e.g., in case of SRVCC). The MSC server is also in charge of TFO and TrFO functions. In many cases, MSC server is collocated with media gateway controller function (MGCF), in charge of creating and releasing connections at MGWs between IMS and CS domains. + +This point is therefore recommended for monitoring and troubleshooting purposes on most metrics concerning communications where roaming between LTE and 2G or 3G occurs. The concerned metrics fall in the service availability, continuity, and speed families mostly. + +### **10.1.6 Measurement point F** + +The policy and charging rule function (PCRF) is the central entity in policy control making policy and charging control (PCC) decisions. The decisions can be based on input from a number of different sources, including: + +- Operator configuration in the PCRF that defines the policies applied to given services. +- Subscription information for a given user, received from the subscriber profile repository (SPR). +- Information about the service received from the application function (AF). +- Information from the access network about what access technology is used, etc. + +The measurement point **F** is meant for monitoring the Rx interface between PCRF and the IMS domain proxy call session control function (P-CSCF). It is recommended for reporting, monitoring and troubleshooting purposes on metrics on service utilisation, availability, continuity, and speed. + +### **10.1.7 Measurement points G1, G2 and G3** + +This group of measurement points corresponds to media gateways (GWs). GWs are important locations to have specific information about evaluation of core network status (IP packets losses, delay and jitter), codec in core, transcoding and use of TrFO. These are points of interest for monitoring and troubleshooting purposes on metrics such as service accuracy and network performance. + +Proper monitoring of media flows (RTP) not only for interworking of services between EPC and other networks is supported by various types of GW: + +- **G1** – IMS MGW – this is a GW used for anchoring media legs between two VoLTE users but also in case of SRVCC (HO from VoLTE to mobile CS) or VoLTE – legacy mobile CS interworking. This gateway should also provide functionality for interworking between VoLTE and fixed VoIP users (with AMR/AMR-WB – ITU-T G.711 transcoding). +- **G2** – PSTN MGW – this is a place where monitoring, reporting and troubleshooting can be applied (for network performance), for outgoing IP (from IP to PSTN) flows. This is also (and this is its most interest) the place where the performance of cancellation of echoes coming from PSTN is performed. +- **G3** – Trunking gateway (TrGW) in case of interconnection with another IP domain operator. + +### **10.1.8 Measurement Points H1, H2, H3 and H4** + +This is the group of measurement points inside IMS platforms. Monitoring information which can be possessed here are related to the signalling traffic. Probes which can be deployed at the platform side should be complementary to the information received from CDRs and counters. Monitoring information which should be gathered at the corresponding measurement points are related to service availability, continuity and utilization. According to the service (voicemail, conferencing, etc.), accuracy and network performance supervisions can also be interesting to track audio problems. + +Instead of having one single point, it is recommended to separate the capture of metrics at the level of different entities: + +- **H1** – is located at the interface between EPC (PDN GW) and IMS (P-CSCF). This point covers passive monitoring of Gm interface, which is the first interface where none tunnelled SIP signalization coming from all users in the network is centralized; +- **H2** – is a global monitoring point localized on IMS platform (comprising at least elements such as I- and S-CSCF, AS and SCC-AS), ideal to make reporting on service utilization as the analysis will be highly statistically reliable. Monitoring data gathered in this point are focused on performance counters and billing data. As the most suitable platform element for gathering statistics may be metric dependent, detailed information on collection interface will be specified in metrics definitions; +- **H3** – measurement point (on call server/MGCF) can be used for an exhaustive view on the signalling protocol concerning all calls outgoing to PSTN network, since the call server is involved in all call negotiations. Service availability metrics (and other with less priority concerning continuity and network performance) are measurable at this point; +- **H4** – controls IBCF, where the interconnection between two operator domains is performed (including charging data records). SIP signalling information for interconnection can be monitored here. + +### **10.1.9 Measurement point J** + +The **J** measurement point is the circuit-switched network counterpart of A point. The same metrics can be measured for similar purposes (except radio network performance), and with the same sampling strategy. + +"Circuit switch", in this case means all possible interfaces: PSTN, 2G/3G PLMN as well as fixed VoIP access behind an FXS port of a DSL router. + +## **10.2 Monitoring strategy** + +This clause describes the location of the metrics that have to be measured according to their usage. In particular, it aims at defining: + +- what needs to be measured, how it will be measured (with what source of information, at what frequency) and why these measurements are needed; +- what kind of measurement tools and where (locations description and number) these measurements are needed. + +### **10.2.1 Reporting** + +The reporting will provide a general view on the service QoS, potentially in a benchmark perspective (between countries, or against domestic competitors), and on its evolution in time (longitudinal view). It can also allow identification of categories of customers that have a degraded QoS. + +![Figure 11 – VoLTE QoS measurement points – reporting. A complex network diagram showing various measurement points (A1, A2, A3, B, C1, C2, D1, D2, F, H1, H2, H3, H4, D3, C3, E, G1, G2, J, G3) for VoLTE QoS. Each point is linked to a list of metrics such as Service availability DB, Call success rate, Premature release ratio, Post dial delay, One way delay, Call setup time, RTP packet loss rate, Core network transmission quality index/stability, and Codecs statistics. The diagram includes components like eNodeB, MME, SGW, PGW, HSS, IMS, P-CSCF, I-S-CSCF, AS, SCC-AS, IBCF, TrGW, PSTN, Fixed VoIP, AGW/CBG, and UTRAN GERAN. It also shows interfaces like S1c, S1u, S11, S5/S8, S6a, S12, S4, S10, S14, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50, S51, S52, S53, S54, S55, S56, S57, S58, S59, S60, S61, S62, S63, S64, S65, S66, S67, S68, S69, S70, S71, S72, S73, S74, S75, S76, S77, S78, S79, S80, S81, S82, S83, S84, S85, S86, S87, S88, S89, S90, S91, S92, S93, S94, S95, S96, S97, S98, S99, S100.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +The diagram illustrates the network architecture for VoLTE and the specific measurement points for QoS reporting. The architecture includes: + +- Radio Access Network (RAN):** eUTRAN (eNodeB), UTRAN GERAN (BSC/RNC). +- Core Network:** MME, SGW, PGW, HSS, IMS (P-CSCF, I-S-CSCF, AS, SCC-AS, IBCF), PSTN, Fixed VoIP, AGW/CBG, TrGW. +- Interfaces:** S1c, S1u, S11, S5/S8, S6a, S12, S4, S10, S14, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50, S51, S52, S53, S54, S55, S56, S57, S58, S59, S60, S61, S62, S63, S64, S65, S66, S67, S68, S69, S70, S71, S72, S73, S74, S75, S76, S77, S78, S79, S80, S81, S82, S83, S84, S85, S86, S87, S88, S89, S90, S91, S92, S93, S94, S95, S96, S97, S98, S99, S100. +- Measurement Points and Metrics:** + - A1, A2, A3:** Service availability DB, Call success rate, Premature release ratio, Post dial delay, Call setup time, RTP packet loss rate, One way delay / Stability, Core network transmission quality index/stability, Codecs statistics. + - B:** Service Availability DB. + - C1, C2, D1, D2:** Service Availability DB, SRVCC HO/EUTRAN HO success rate. + - F:** Service availability DB, Call setup time, RTP packet loss rate, Core network transmission quality index/stability, Codecs statistics. + - H1, H2, H3, H4:** Service availability DB, Network efficiency ratio, Premature release ratio, SRVCC HO success rate (H2), Call setup time (H1), Call success rate, Total number of customers (H2), Number of active customers (H2), Total number of calls (H2), Mean duration of calls (H2). + - D3, C3, E:** Service availability DB, SRVCC HO/EUTRAN HO success rate. + - G1, G2, J, G3:** Service availability DB, Call success rate, Network efficiency ratio, Premature release ratio, Call setup time, SRVCC HO success rate. + - Other points:** Various other measurement points (e.g., between eNodeB and MME, between MME and SGW, between SGW and PGW, between PGW and IP Core network, between IP Core network and IMS, between IMS and PSTN, between PSTN and Fixed VoIP, between Fixed VoIP and AGW/CBG, between AGW/CBG and TrGW) with associated metrics like Call success rate, Premature release ratio, One way delay, MOS LQOx, One way delay stability, EUTRAN HO success rate, SRVCC HO success rate, and Stability of MOS LQOx. + +Figure 11 – VoLTE QoS measurement points – reporting. A complex network diagram showing various measurement points (A1, A2, A3, B, C1, C2, D1, D2, F, H1, H2, H3, H4, D3, C3, E, G1, G2, J, G3) for VoLTE QoS. Each point is linked to a list of metrics such as Service availability DB, Call success rate, Premature release ratio, Post dial delay, One way delay, Call setup time, RTP packet loss rate, Core network transmission quality index/stability, and Codecs statistics. The diagram includes components like eNodeB, MME, SGW, PGW, HSS, IMS, P-CSCF, I-S-CSCF, AS, SCC-AS, IBCF, TrGW, PSTN, Fixed VoIP, AGW/CBG, and UTRAN GERAN. It also shows interfaces like S1c, S1u, S11, S5/S8, S6a, S12, S4, S10, S14, S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28, S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41, S42, S43, S44, S45, S46, S47, S48, S49, S50, S51, S52, S53, S54, S55, S56, S57, S58, S59, S60, S61, S62, S63, S64, S65, S66, S67, S68, S69, S70, S71, S72, S73, S74, S75, S76, S77, S78, S79, S80, S81, S82, S83, S84, S85, S86, S87, S88, S89, S90, S91, S92, S93, S94, S95, S96, S97, S98, S99, S100. + +**Figure 11 – VoLTE QoS measurement points – reporting** + +All measurement points can actually provide data for reporting. Even not fully representative data, like those gathered from intrusive measurements, can be valuable for this purpose. + +The following dashboards can be built based on such measurements: + +- General view of the service utilisation (number of customers, number of calls, call durations, churn rate). +- Performance of service platforms and network equipment (service availability and continuity). +- QoS counters (availability, PDD, mean opinion score (MOS), call continuity). + +### 10.2.2 Monitoring + +All measurement points can provide data for monitoring, as long as they can provide a view on either end-to-end QoS or the contribution of a network section to this QoS. + +The hot mode monitoring (alarm raising) will provide real time information related to degradation of the service QoS impacting a great number of customers. + +![Figure 12 – VoLTE QoS measurement points – monitoring. A complex network diagram showing various measurement points (A1, A2, A3, B, C1, C2, D1, D2, F, H1, H2, H3, H4, D3, C3, E, G1, G2, J, G3) for VoLTE QoS monitoring. The diagram includes components like eNodeB, MME, SGW, PGW, HSS, IMS, PSTN, and various interconnections. Measurement points are labeled with specific QoS metrics such as Call success rate, Registration success rate, Premature release ratio, Post dial delay, Call setup time, RTP packet loss rate, One way delay / Stability, Radio quality, Core network transmission quality index/stability, Codecs statistics, Tracking area update (C1), EUTRAN HO success rate, Call setup time, MOS LQOx/stability, Speech signal measurements, Echo, SRVCC HO success rate, Network efficiency ratio, and Total number of calls (H2).](05eb72d372e4bf78e3d6a64949d77bcc_img.jpg) + +The diagram illustrates the network architecture for VoLTE and the locations of various QoS measurement points. The core network consists of eNodeBs connected to an MME, which is further connected to SGWs and a PGW. The PGW connects to the IP Core network and the HSS. The IP Core network includes components like PCRF, SCC-AS, AS, P-CSCF, I/S-CSCF, IMS, and IBCF. The network also interfaces with SRVCC, UTRAN GERAN, Fixed VoIP, PSTN, and Interconnections with TPO. Measurement points are indicated by letters (A1, A2, A3, B, C1, C2, D1, D2, F, H1, H2, H3, H4, D3, C3, E, G1, G2, J, G3) and are associated with specific QoS metrics listed in blue boxes. For example, point A1 is associated with metrics like Call success rate, Registration success rate, and Premature release ratio. Point B is associated with Radio quality. Point C1 is associated with Tracking area update (C1) and EUTRAN HO success rate. Point D2 is associated with Call setup time, RTP packet loss rate, and Core network transmission quality index/stability. Point F is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point G1 is associated with RTP packet loss rate, Core network transmission quality index/stability, Codecs statistics (G1), and Echo (G2). Point G2 is associated with Call success rate, Post dial delay, One way delay/stability, MOS LQOx/stability, Speech signal measurements, and Echo. Point H2 is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point J is associated with Call setup time, RTP packet loss rate, Core network transmission quality index/stability, and Codecs statistics. Point E is associated with SRVCC HO success rate. Point D3 is associated with Call success rate, Network efficiency ratio, Registration success rate, Premature release ratio, Call setup time, and SRVCC HO success rate. Point C3 is associated with SRVCC HO success rate. Point G3 is associated with Call success rate, Post dial delay, One way delay/stability, MOS LQOx/stability, Speech signal measurements, and Echo. Point H3 is associated with Call success rate, Premature release ratio, One way delay/stability, Radio quality, EUTRAN / SRVCC HO success rate, MOS LQOx/stability, Speech signal measurements, and Echo. Point H4 is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point A3 is associated with Call success rate, Premature release ratio, One way delay/stability, Radio quality, EUTRAN / SRVCC HO success rate, MOS LQOx/stability, Speech signal measurements, and Echo. Point A2 is associated with Call success rate, Registration success rate, Premature release ratio, Post dial delay, Call setup time, RTP packet loss rate, One way delay / Stability, Radio quality, Core network transmission quality index/stability, and Codecs statistics. Point B is associated with Radio quality. Point C1 is associated with Tracking area update (C1) and EUTRAN HO success rate. Point C2 is associated with Call setup time, RTP packet loss rate, Core network transmission quality index/stability, and Codecs statistics. Point D1 is associated with Call success rate, Premature release ratio, Post dial delay, One way delay/stability, MOS LQOx/stability, Speech signal measurements, and Echo. Point D2 is associated with Call setup time, RTP packet loss rate, Core network transmission quality index/stability, and Codecs statistics. Point F is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point H1 is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point H2 is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point H3 is associated with Call success rate, Premature release ratio, One way delay/stability, Radio quality, EUTRAN / SRVCC HO success rate, MOS LQOx/stability, Speech signal measurements, and Echo. Point H4 is associated with Call success rate, Registration success rate (H1, H2), Premature release ratio, Call setup time (H1), SRVCC HO success rate (H2), and Total number of calls (H2). Point D3 is associated with Call success rate, Network efficiency ratio, Registration success rate, Premature release ratio, Call setup time, and SRVCC HO success rate. Point C3 is associated with SRVCC HO success rate. Point E is associated with SRVCC HO success rate. Point G1 is associated with RTP packet loss rate, Core network transmission quality index/stability, Codecs statistics (G1), and Echo (G2). Point G2 is associated with Call success rate, Post dial delay, One way delay/stability, MOS LQOx/stability, Speech signal measurements, and Echo. Point J is associated with Call setup time, RTP packet loss rate, Core network transmission quality index/stability, and Codecs statistics. Point G3 is associated with Call success rate, Post dial delay, One way delay/stability, MOS LQOx/stability, Speech signal measurements, and Echo. + +Figure 12 – VoLTE QoS measurement points – monitoring. A complex network diagram showing various measurement points (A1, A2, A3, B, C1, C2, D1, D2, F, H1, H2, H3, H4, D3, C3, E, G1, G2, J, G3) for VoLTE QoS monitoring. The diagram includes components like eNodeB, MME, SGW, PGW, HSS, IMS, PSTN, and various interconnections. Measurement points are labeled with specific QoS metrics such as Call success rate, Registration success rate, Premature release ratio, Post dial delay, Call setup time, RTP packet loss rate, One way delay / Stability, Radio quality, Core network transmission quality index/stability, Codecs statistics, Tracking area update (C1), EUTRAN HO success rate, Call setup time, MOS LQOx/stability, Speech signal measurements, Echo, SRVCC HO success rate, Network efficiency ratio, and Total number of calls (H2). + +Figure 12 – VoLTE QoS measurement points – monitoring + +### 10.2.3 Troubleshooting + +The troubleshooting will provide additional information by: + +- In depth analysis of customer or access below the threshold, by trying to reproduce the causes for the encountered problems and analysing data collected during the problem by different sources (CDRs, probes). +- Remote testing/configuration checks, including trace capture and analysis at major network nodes. + +– On site investigations, including trace capture at the customer premise or in the access network. + +![Figure 13 – VoLTE QoS measurement points – troubleshooting. This diagram illustrates the network architecture for VoLTE and identifies key measurement points for troubleshooting. The architecture includes User Equipment (UE) connected to eNodeBs (eUTRAN), which are part of the Evolved Packet Core (EPC) containing the MME, SGW, and PGW. The MME is connected to the HSS, PCRF, and IMS (IP Multimedia Subsystem). The IMS includes components like SCC-AS, AS, P-CSCF, I/S-CSCF, and IBCF. The PGW connects to the IP Core network, which in turn connects to the PSTN via an AGW/CBGF and MGW. The diagram also shows interconnections with SRVCC, UTRAN GERAN, Fixed VoIP, and TrGW. Various measurement points are highlighted with colored boxes containing lists of KPIs such as call success rate, registration success rate, premature release ratio, post dial delay, call set-up time, RTP packet loss rate, one way delay/stability, radio quality, core network transmission quality index/stability, speech signal measurements, and echo. These measurement points are distributed across the network, from the UE to the PSTN interconnection points.](85e2327652d513a7fee8fdbf97ad06f1_img.jpg) + +Figure 13 – VoLTE QoS measurement points – troubleshooting. This diagram illustrates the network architecture for VoLTE and identifies key measurement points for troubleshooting. The architecture includes User Equipment (UE) connected to eNodeBs (eUTRAN), which are part of the Evolved Packet Core (EPC) containing the MME, SGW, and PGW. The MME is connected to the HSS, PCRF, and IMS (IP Multimedia Subsystem). The IMS includes components like SCC-AS, AS, P-CSCF, I/S-CSCF, and IBCF. The PGW connects to the IP Core network, which in turn connects to the PSTN via an AGW/CBGF and MGW. The diagram also shows interconnections with SRVCC, UTRAN GERAN, Fixed VoIP, and TrGW. Various measurement points are highlighted with colored boxes containing lists of KPIs such as call success rate, registration success rate, premature release ratio, post dial delay, call set-up time, RTP packet loss rate, one way delay/stability, radio quality, core network transmission quality index/stability, speech signal measurements, and echo. These measurement points are distributed across the network, from the UE to the PSTN interconnection points. + +G.1028(19)\_F13 + +**Figure 13 – VoLTE QoS measurement points – troubleshooting** + +## 10.3 Available tools in ITU-T standards + +Though based on new network technologies, VoLTE remains a telephony offer subject to all requirements expressed by end users concerning its usage, and in particular when it comes to QoS. Therefore, provisions already contained in existing ITU-T Recommendations concerning the procurement and evaluation of perceived quality of voice services apply in most cases to VoLTE as well. + +### 10.3.1 Definition of key performance indicators + +As can be seen in previous sections (in particular in Table 3), the metrics representative of the quality of service as perceived by end users are not specific to VoLTE. Most of them are already defined in + +[ITU-T P.10], and these definitions apply for this context. Following are the details of these references: + +- Service availability: see service accessibility performance (clause 3.1.1.2.2 in [ITU-T E.800]). +- Post dialling delay: see call set-up time (clause 3.1.1.2.1 in [ITU-T E.800]). +- Voice quality (MOS-LQ, see "Speech Quality" (S-28) in [ITU-T P.10] or the various definitions provided in [ITU-T P.800.1]). +- Mouth-to-ear delay: not defined as such in ITU-T Recommendations. See however mean one-way propagation time (M-1) in [ITU-T P.10], as well as explanation in [ITU-T G.114]. +- Call drop ratio: see telephony cut off call ratio in [ITU-T E.804]. +- Speech bandwidth (NB, WB or SWB): amendment 4 of [ITU-T P.10] gives very detailed definition of various audio bandwidth used in telephony. + +Registration success rate for VoLTE is not defined in Recommendations. [ITU-T E.804] (clause 7.2.2.1) defines a network selection and registration failure ratio, but this disregards the specificity of IMS registration. + +As far as the main QoS dimensions are concerned, the four viewpoints of QoS (see Figure 14) defined in [ITU-T G.1000] are also useful in the context of VoLTE. + +![Diagram illustrating the four viewpoints of QoS: Customer's QoS requirements, QoS offered by provider, QoS achieved by provider, and QoS perceived by customer.](1cac1845cf99a3f64ae00cd2bb4f9ed7_img.jpg) + +The diagram illustrates the four viewpoints of QoS, organized into two columns separated by a vertical dashed line. The left column is labeled 'Customer' and the right column is labeled 'Service provider'. In the 'Customer' column, there are two boxes: 'Customer's QoS requirements' at the top and 'QoS perceived by customer' at the bottom, connected by a vertical blue arrow pointing upwards. In the 'Service provider' column, there are two boxes: 'QoS offered by provider' at the top and 'QoS achieved by provider' at the bottom, connected by a vertical blue arrow pointing downwards. Horizontal blue arrows connect the boxes across the dashed line: from 'Customer's QoS requirements' to 'QoS offered by provider' and from 'QoS achieved by provider' to 'QoS perceived by customer'. The diagram is labeled 'G.1028(16)\_F14' at the bottom right. + +Diagram illustrating the four viewpoints of QoS: Customer's QoS requirements, QoS offered by provider, QoS achieved by provider, and QoS perceived by customer. + +Figure 14 – The four viewpoints of QoS (source: [ITU-T G.1000]) + +As far as it concerns metrics representative of the underlying network layers, [ITU-T Y.1540] provides information on IP-related metrics, while no ITU-T standards address radio metrics. + +### 10.3.2 Tools and models for the measurement and prediction of voice quality + +There are two approaches for the assessment of end-to-end voice quality: + +- Parametric tools take advantage of the good correlation between technical information of a connection and the corresponding end-to-end quality as perceived by end-users, to produce a relatively accurate estimate at a cheap implementation cost. Such a tool can be envisaged at edge points, close to the end-user, for a better prediction of individual quality, or inside the network, for a good knowledge of the general impact of network performance on end-to-end quality. [ITU-T P.564] describes a general class of parametric voice quality prediction models that provide highly scalable voice quality estimation using information in the IP/UDP/RTP header of packets. In addition, [ITU-T P.564] provides performance criteria for models of this type that operate on narrowband speech. + +- Another type of parametric tool is the E-model described in [ITU-T G.107], which is a widely used transmission planning tool. Most factors present in the model (now adapted for IP transmission and WB telephony, see [ITU-T G.107.1]) apply for VoLTE. +- Signal-based models are much more complicated than parametric tools since they require a capture and an analysis of the speech signal. This is why they are mostly used in a point-to-point perspective, in order to measure very accurately the end-to-end quality of a voice service at a given time and at a given location (and most of the time for a given service with a given end device). ITU-T developed several such tools: [ITU-T P.862] and [ITU-T P.863] for full-reference models, and [ITU-T P.563] for a single-ended implementation (restricted to narrowband telephony). + +### 10.3.3 Applicable acceptability thresholds and targets + +In general, ITU-T do not specify acceptability targets for end-user's metrics. However, there is a notorious exception for end-to-end delay, where [ITU-T G.114] specifies (in clause 4) a first threshold at 150 ms below which most users do not notice the delay, and a second one at 400 ms above which the quality is considered as unacceptable. + +R factor values computed with the E-model from [ITU-T G.107] (and translated into MOS-CQE scores, as shown on Figure 15) can also be compared with acceptability thresholds. Recommendation [ITU-T G.109] defines such categories (for NB telephony only) reproduced in Table 8: + +**Table 8 – Definition of categories of speech transmission quality (source: [ITU-T G.109])** + +| R-value range | Speech transmission quality category | User satisfaction | +|-------------------|--------------------------------------|-------------------------------| +| $90 \leq R < 100$ | Best | Very satisfied | +| $80 \leq R < 90$ | High | Satisfied | +| $70 \leq R < 80$ | Medium | Some users dissatisfied | +| $60 \leq R < 70$ | Low | Many users dissatisfied | +| $50 \leq R < 60$ | Poor | Nearly all users dissatisfied | + +![Figure 15: MOS-CQE as function of rating factor (source: [ITU-T G.107]). The graph shows a curve representing the relationship between the Mean Opinion Score (MOS) on the y-axis (ranging from 1 to 5) and the rating factor (R) on the x-axis (ranging from 0 to 100). The curve starts at (0, 1) and increases monotonically, leveling off towards (100, 5). The y-axis is labeled 'MOS' and has ticks for 'Excellent 5', 'Good 4', 'Fair 3', 'Poor 2', and 'Bad 1'. The x-axis is labeled 'R' and has ticks at 0, 20, 40, 60, 80, and 100. A small label 'G.1028(16)_F15' is present at the bottom right of the graph area.](1cd6a2d6e58e0e6d75c879a999be06ef_img.jpg) + +Figure 15: MOS-CQE as function of rating factor (source: [ITU-T G.107]). The graph shows a curve representing the relationship between the Mean Opinion Score (MOS) on the y-axis (ranging from 1 to 5) and the rating factor (R) on the x-axis (ranging from 0 to 100). The curve starts at (0, 1) and increases monotonically, leveling off towards (100, 5). The y-axis is labeled 'MOS' and has ticks for 'Excellent 5', 'Good 4', 'Fair 3', 'Poor 2', and 'Bad 1'. The x-axis is labeled 'R' and has ticks at 0, 20, 40, 60, 80, and 100. A small label 'G.1028(16)\_F15' is present at the bottom right of the graph area. + +**Figure 15 – MOS-CQE as function of rating factor (source: [ITU-T G.107])** + +Recommendation [ITU-T Y.1541] also provides performance objectives for various QoS classes (see Table 9) based on IP-network metrics defined and specified in [ITU-T Y.1540]. VoLTE falls into class 0 or 1: + +**Table 9 – IP network QoS class definitions and network performance objectives (source: [ITU-T Y.1541])** + +| Network performance parameter | Nature of network performance objective | QoS classes | | +|-------------------------------|--------------------------------------------------------------------------|--------------------|--------------------| +| | | Class 0 | Class 1 | +| IPTD | Upper bound on the mean IPTD | 100 ms | 400 ms | +| IPDV | Upper bound on the $1 - 10^{-3}$ quantile of IPTD minus the minimum IPTD | 50 ms | 50 ms | +| IPLR | Upper bound on the packet loss probability | $1 \times 10^{-3}$ | $1 \times 10^{-3}$ | +| IPER | Upper bound | $1 \times 10^{-4}$ | | + +# Annex A + +## List of degradations encountered by end-users of VoLTE service and their potential causes + +(This annex forms an integral part of this Recommendation.) + +This annex is completed for CSFB specific causes by clause 9 of [ITU-T G.1028.2]. + +## A.1 QoS problem linked to call session performance + +Table A.1 – degradations related to call session performance and their potential causes + +| Kind of degradation | Possible reasons: | Location | +|------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------| +| Identification Failure | – Problem with MME, HSS or PCRF | EPC | +| Unavailability of basic call | – Error in scheduling
– Radio resource control (RRC) connection set-up failure (reception of RRC connection reject, or expiry of timer T300, no RRC connection set-up complete sent after reception of RRC connection set-up).
– Not available due to load (serving gateway (SGW) or packet data network gateway (PGW))
– Failed negotiation (no allocation of QCI, no codec match, SIP preconditions unmet, etc.)
– Reception of several SIP error codes (e.g., 401 = Unauthorized, 405 = Method Not Allowed, etc.)
– Reception of SIP CANCEL from IMS
– TD internal timer expired, causing a "SessionSetupFailureTimeout" | eUTRAN
EPC | +| High post dialling delay | – Load
– Interworking between systems
– Use of SIP preconditions
– CS fall back or IMS tromboning at call set-up | All | +| Link failure | – Bad negotiation between two equipments of the network during call establishment (bad codec management) | eUTRAN/ EPC | +| White call | – Terminal is not able to code or decode speech while the signalling is OK for the communication | Terminal | +| Call drop | – Terminal bug, bad covered area, handover/SRVCC failures due to cells neighbourhood problem, etc.
– RRC connection drop (at reception of RRC connection re-establishment reject, or expiry of timer T301 or in case RRC connection release is received before new RRC connection set-up attempt)
– Link failure: System failure, bad re-negotiation between two equipments of the network during call.
– Reception of SIP status code 500 (Server Internal Error)
– No RTP packet received during a period longer than "SessionDropTimeout" TD internal timer
– No SIP 200 OK on BYE is received within the time measured by "SessionHangupTimeout" TD internal timer | Terminal/
eUTRAN
EPC | + +## A.2 QoS problem linked to perceived speech quality + +**Table A.2 – Degradations related to perceived speech quality and their potential causes** + +| Kind of degradation | Possible reasons: | Location | +|----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------| +| Noise | – Disturbing comfort noise generation (CNG) due to bad noise reduction. | Terminal | +| | – Noise due to bad electronic implementation on terminal (e.g., analogue /digital conversion). | | +| | – Disturbing residual noise due to bad noise reduction. | | +| | – Background noise (street, car, etc.). | | +| | – Additional noise due to eUTRAN configuration problem. | | +| Echo | – Bad performance of acoustic echo cancellation (AEC)/ No AEC. As reminder: Acoustic echo is the coupling between the loudspeaker and the microphone of the phone terminal. | Networks | +| | – Bad performance of electric echo cancellation (EEC)/No EEC . Reminder: Electrical echo is due to digital to analogue transformation for a call between mobile terminal and PSTN (No electrical echo for mobile to mobile call). | | +| Low/high speech level | – Bad performance of automatic gain control (AGC)/No AGC. | Terminal | +| Encoding / decoding issues | – Narrowband instead of wideband speech quality:
  • • Remote terminal not WB
  • • HO towards 2G
  • • Call with PSTN, 2G, mobile platforms, etc. where wideband is not deployed.
  • • Interworking with CS 3G not WB
| Terminal/ eUTRAN | +| | – Lower WB-AMR bitrate/AMR (Loaded cell, autonomous mode, etc.) leading to distortion on speech signal.
– Many transcodings (for example with call to voicemail) leading to distortion on speech signal
– Rebuffering and time scaling causing distortion | Terminal/ eUTRAN | +| Terminal Acoustic | – Although WB-AMR codec is supported, the acoustical performance of the terminal (on receiving and/or sending side) is not wideband compliant.
– Not well-balanced acoustic terminal can lead to a sound which seems too aggressive, too muffled, etc.
– Distortion due to transducers. | Terminal | +| Chopped Conversation | – Bad VAD/DTX/DRX implementation.
– Problem with voice quality enhancement (VQE) algorithm. | Terminal | +| | – IP packet loss or jitter in network (congestion, QoS prioritization, UL/DL scheduling delays, radio retransmissions, handover).
– Bad handling of IP packet loss and inter-arrival jitter by jitter buffers or packet loss concealment (PLC) inside terminals | All | +| DTMF not recognized | – Problem with in-band or out-band processing | All | + +**Table A.2 – Degradations related to perceived speech quality and their potential causes** + +| Kind of degradation | Possible reasons: | Location | +|----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------| +| E2E delay |
  • – Network load.– Media handling (packet construction, jitter buffer management)
  • – Speech processing in terminals
  • – Random access channel (RACH) upon receiving handover command
  • – RACH/contention procedure
  • – Additional RACH attempts
  • – Dynamic scheduling, link adaptation
  • – Radio link failure/re-establishment during handover (possibly different cell)
| All | +| RTP/IP packet loss |
  • – Network congestion (several causes : traffic load, distance from cell centre causing activation of TTI bundling, for instance)
  • – Jitter buffers not adapted to actual jitter amount or packet size (can depend on use of RoHC or not)
| EPC/
Terminal | +| RTP/IP Desequencing |
  • – New route after a problem such as congestion
| EPC | +| Network Delay Variation (Jitter) |
  • – Network congestion
  • – Jitter buffers not adapted
| EPC/
Terminal | +| Radio degradations |
  • – Limit of the cell coverage
  • – Interference
  • – Area not well covered (obstacle, etc.)
  • – Bad radio optimization
  • – Radio loss profile
  • – Bad radio scheduling
  • – No or bad use of hybrid automatic-repeat-request (HARQ) mechanisms
  • – Etc.
| eUTRAN | +| Handover latency |
  • – Latency due to new route after HO or SRVCC
| EPC/CS network | + +# Bibliography + +- [b-GSMA IR.34] GSMA IR.34 v 9.1 (2013), *Guidelines for IPX Provider networks.* +- [b-GSMA IR.92] GSMA IR.92 v 7.0 (2013), *IMS Profile for Voice and SMS.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.107.1-201906-I_PDF-E/raw.md b/marked/G/T-REC-G.107.1-201906-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..b0fddcb32ba6e6a0315d8ae3c224828dd480757b --- /dev/null +++ b/marked/G/T-REC-G.107.1-201906-I_PDF-E/raw.md @@ -0,0 +1,455 @@ + + +International Telecommunication Union + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.107.1** + +(06/2019) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +International telephone connections and circuits – +Transmission planning and the E-model + +--- + +**Wideband E-model** + +Recommendation ITU-T G.107.1 + +ITU-T + +![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a stylized globe with a red lightning bolt striking across it. The letters "ITU" are prominently displayed in blue and white within the globe. + +ITU logo + +International +Telecommunication +Union + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| Transmission planning and the E-model | G.100–G.109 | +| General Recommendations on the transmission quality for an entire international telephone connection | G.110–G.119 | +| General characteristics of national systems forming part of international connections | G.120–G.129 | +| General characteristics of the 4-wire chain formed by the international circuits and national extension circuits | G.130–G.139 | +| General characteristics of the 4-wire chain of international circuits; international transit | G.140–G.149 | +| General characteristics of international telephone circuits and national extension circuits | G.150–G.159 | +| Apparatus associated with long-distance telephone circuits | G.160–G.169 | +| Transmission plan aspects of special circuits and connections using the international telephone connection network | G.170–G.179 | +| Protection and restoration of transmission systems | G.180–G.189 | +| Software tools for transmission systems | G.190–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.107.1 + +## Wideband E-model + +## Summary + +Recommendation ITU-T G.107.1 gives the algorithm for the wideband (WB) version of the E-model as the common ITU-T transmission rating model for planning speech services that provide WB speech transmission (50-7000 Hz). This computational model can be useful to transmission planners, to help ensure that users will be satisfied with end-to-end transmission performance. The primary output of the model is a scalar rating of transmission quality. A major feature of this model is the use of transmission impairment factors that reflect the effects of different types of degradations occurring on the entire transmission path, mouth-to-ear. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.107.1 | 2011-12-14 | 12 | 11.1002/1000/11453 | +| 2.0 | ITU-T G.107.1 | 2015-06-29 | 12 | 11.1002/1000/12506 | +| 3.0 | ITU-T G.107.1 | 2019-06-29 | 12 | 11.1002/1000/13925 | + +## Keywords + +E-model, speech quality, transmission planning, wideband. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 WB E-model ..... | 3 | +| 6.1 Introduction ..... | 3 | +| 6.2 Transmission rating scale of the WB E-model..... | 3 | +| 7 The structure and basic algorithms of the WB E-model..... | 5 | +| 7.1 Calculation of the transmission rating factor, R..... | 6 | +| 7.2 Basic signal-to-noise ratio, $R_o$ , WB ..... | 6 | +| 7.3 Simultaneous impairment factor, $I_s$ , WB ..... | 6 | +| 7.4 Delay impairment factor, $I_d$ , WB ..... | 6 | +| 7.5 Equipment impairment factor, $I_e$ , WB ..... | 7 | +| 7.6 Advantage factor, A..... | 8 | +| 7.7 Default values ..... | 8 | +| Annex A – MOS values derived from the transmission rating factor R ..... | 9 | +| Bibliography..... | 10 | + + + +## Recommendation ITU-T G.107.1 + +## Wideband E-model + +## 1 Scope + +This Recommendation describes the wideband (WB) version of a computational model, known as the E-model, that has proven useful as a transmission planning tool for assessing the combined effects of variations in several transmission parameters that affect conversational1 quality. This computational model can be used, for example, by transmission planners to help ensure that users will be satisfied with end-to-end transmission performance whilst avoiding over-engineering of networks. It must be emphasized that the primary output from the model is the "rating factor" $R$ , but this can be transformed to give estimates of customer opinion. Such estimates are only made for transmission planning purposes and not for actual customer opinion prediction (for which there is no agreed-upon model recommended by the ITU-T). + +This version is an adapted version of the NB (300-3400 Hz) E-model, typically referred to as "the E-model", which is described in [ITU-T G.107]. The WB version addresses scenarios which include WB (50-7000 Hz) transmission. It does not replace the narrowband (NB) E-model. Instead, it describes a separate WB-version of the model that uses, within limits, similar concepts and input parameters as the NB E-model. The current version captures the effects of talker echo, absolute delay, WB speech coding, and voice-over-IP packet-loss. Degradations which are covered but have not yet been studied in detail are listener echo. Degradations which are not yet covered are loudness loss, non-optimum sidetone levels, background noise at the sending and receiving side, circuit noise and quantizing distortions. + +For many parameter combinations of high importance to transmission planners, ITU-T G.107.1 can be used with confidence (e.g., loudness loss, coding distortions), but for some parameter combinations of high importance (e.g., the effects of delay in conjunction with other impairments), WB E-model predictions have been questioned and are currently under study. + +Regarding the interpretation of the WB E-model ratings, note that the current versions of [b-ITU-T G.108], [b-ITU-T G.108.1] and [b-ITU-T G.109] do not refer to the WB version described here, but only to the NB version of the E-model described in [ITU-T G.107]. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +[ITU-T G.107] Recommendation ITU-T G.107 (2015), *The E-model: a computational model for use in transmission planning*. +<> + +--- + +1 Conversational quality in this context refers to transmission characteristics, e.g., long transmission times, effects of talker echoes, etc. However, the E-model, as described in this Recommendation, is not intended to model transmission impairments during double talk situations. + +- [ITU-T G.113] Recommendation ITU-T G.113 (2007), *Transmission impairments due to speech processing*. +[](http://www.itu.int/rec/T-REC-G.113) +- [ITU-T G.722] Recommendation ITU-T G.722 (2012), *7 kHz audio-coding within 64 kbit/s*. +[](http://www.itu.int/rec/T-REC-G.722) +- [ITU-T O.41] Recommendation ITU-T O.41 (1994), *Psophometer for use on telephone-type circuits*. +[](http://www.itu.int/rec/T-REC-O.41) +- [ITU-T P.800] Recommendation ITU-T P.800 (1996), *Methods for subjective determination of transmission quality*. +[](http://www.itu.int/rec/T-REC-P.800) +- [ITU-T P.833] Recommendation ITU-T P.833 (2001), *Methodology for derivation of equipment impairment factors from subjective listening-only tests*. +[](http://www.itu.int/rec/T-REC-P.833) +- [ITU-T P.833.1] Recommendation ITU-T P.833.1 (2009), *Methodology for the derivation of equipment impairment factors from subjective listening-only tests for wideband speech codecs*. +[](http://www.itu.int/rec/T-REC-P.833.1) +- [ITU-T P.834] Recommendation ITU-T P.834 (2015), *Methodology for the derivation of equipment impairment factors from instrumental models*. +[](http://www.itu.int/rec/T-REC-P.834) +- [ITU-T P.834.1] Recommendation ITU-T P.834.1 (2015), *Methodology for the derivation of equipment impairment factors from instrumental models for wideband speech codecs*. +[](http://www.itu.int/rec/T-REC-P.834.1) + +## 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +None. + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|-----------------------------| +| LSTR | Listener Sidetone Rating | +| MOS | Mean Opinion Score | +| NB | Narrowband | +| OLR | Overall Loudness Rating | +| PCM | Pulse Code Modulation | +| RLR | Receive Loudness Rating | +| SLR | Send Loudness Rating | +| STMR | Sidetone Masking Rating | +| TELR | Talker Echo Loudness Rating | +| WB | Wideband | + +## 5 Conventions + +None. + +# 6 WB E-model + +## 6.1 Introduction + +The complexity of modern networks requires that, for transmission planning, the many transmission parameters be not only considered individually, but also that their combined effects be taken into account. This can be done by "expert, informed guessing", but a more systematic approach is desirable, such as by using a computational model. The output from the model described here is a scalar transmission rating value, $R$ , which varies directly with the overall conversational quality. [ITU-T G.113] gives guidance about specific impairments, including combined effects based upon a simplification of the model. + +## 6.2 Transmission rating scale of the WB E-model + +For the narrowband (NB) case described in [ITU-T G.107], the transmission rating scale ranges from $R = 0$ (lowest possible quality) to $R = 100$ (optimum quality). On this scale, a default NB transmission channel including logarithmic Pulse Code Modulation (PCM) coding and a noise floor (default parameter values according to Table 2 of [ITU-T G.107]) obtains a rating of $R = 93.2$ . For a WB speech transmission channel, the quality is generally judged better than that for a NB channel. Thus, this scale range was extended in order to be also applicable to WB transmission scenarios. In the present WB version, the E-model is defined for a WB transmission channel of 50-7000 Hz, as it is defined in [ITU-T G.722]. + +Unfortunately, it is not possible to obtain direct human judgements on the $R$ -scale, as this scale has additivity properties which are not reflected by ordinary rating scales. Instead, for NB conditions, ITU-T recommends collecting judgements on a 5-point absolute category rating scale, see [ITU-T P.800]. The mean rating, averaged over all test participants and stimuli reflecting the same circuit condition, is then called a mean opinion score (MOS). + +It has been shown that MOS ratings differ between tests where only NB stimuli are presented and tests where both NB/WB or purely WB stimuli are presented, as the use of the scale is largely influenced by the stimulus set. On the other hand, there is also experimental evidence that judgements for WB samples collected in a purely WB context do not differ significantly from those collected in a mixed NB/WB context, see [b-Barriac] and [b-Takahashi]. In addition to the stimulus bandwidth, test results are influenced by the test participant group, the language, the participants' native country, etc. [b-Möller-01]. For a NB context, an average S-shaped relationship is defined between the $R$ -scale (range [0;100]) and MOS ratings (range [1;4.5]) collected from "average" test participants in an "average" experimental setting, see Annex B and Appendix I of [ITU-T G.107]. + +For a WB or a mixed NB/WB context, the $R$ -scale was extended in a way which leaves the NB use of the scale unaffected, including the position of the reference connection (default parameter settings according to Table 2 of [ITU-T G.107]). Such an extension can be based on pairs of auditory tests in which the same (NB) test stimuli have been judged once in a purely NB and once in a mixed NB/WB context. The judgements on these common stimuli define a relationship between the use of the MOS-scale in a NB and in a mixed NB/WB context [b-Raake-01]. + +Two pairs of tests have been carried out and will be considered in the following. Details on parts of the tests can be found in [b-Möller-02]. The MOS results from these tests have been transformed to the $R$ -scale using the NB transformation rule given in Annex B of [ITU-T G.107]. The resulting $R_{NB}$ + +values (NB test) and $R_{NB/WB}$ values (mixed NB/WB test) for the conditions which were common in each pair are displayed in Figure 1. + +![Figure 1: Comparison between R-values derived in a NB and in a mixed NB/WB context. The figure contains two scatter plots. The top plot shows R_NB on the y-axis (0 to 150) versus R_NB/WB on the x-axis (0 to 100). A diagonal line represents the relationship, ending at a point labeled R_max = 129. The bottom plot shows R_NB on the y-axis (0 to 140) versus R_NB/WB on the x-axis (0 to 100). A diagonal line represents the relationship, ending at a point labeled R_max = 129.5. Both plots show data points following the diagonal line, indicating a strong correlation between the two R-value scales.](4e0ade2f41b66d5602160da5cc978274_img.jpg) + +The figure consists of two vertically stacked scatter plots. The top plot has $R_{NB}$ on the y-axis (0 to 150) and $R_{NB/WB}$ on the x-axis (0 to 100). A solid diagonal line starts at (0,0) and ends at (100, 129), with an arrow pointing to the endpoint labeled $R_{max} = 129$ . Data points are represented by open circles. The bottom plot has $R_{NB}$ on the y-axis (0 to 140) and $R_{NB/WB}$ on the x-axis (0 to 100). A solid diagonal line starts at (0,0) and ends at (100, 129.5), with an arrow pointing to the endpoint labeled $R_{max} = 129.5$ . Data points are represented by open circles. Both plots show a strong positive correlation between the two R-value scales. + +Figure 1: Comparison between R-values derived in a NB and in a mixed NB/WB context. The figure contains two scatter plots. The top plot shows R\_NB on the y-axis (0 to 150) versus R\_NB/WB on the x-axis (0 to 100). A diagonal line represents the relationship, ending at a point labeled R\_max = 129. The bottom plot shows R\_NB on the y-axis (0 to 140) versus R\_NB/WB on the x-axis (0 to 100). A diagonal line represents the relationship, ending at a point labeled R\_max = 129.5. Both plots show data points following the diagonal line, indicating a strong correlation between the two R-value scales. + +**Figure 1 – Comparison between $R$ -values derived in a NB and in a mixed NB/WB context** + +Due to the use of the NB relationship between MOS and $R$ for deriving the $R_{NB/WB}$ values, the maximum $R_{NB/WB}$ value corresponding to MOS = 4.5 equals 100. The corresponding $R_{NB}$ value of the panels in Figure 1 shows the amount by which the $R$ -scale has to be extended in a NB/WB context. This maximum value is around $R_{max} = 129$ . In other words, the NB transmission rating scale of the E-model has been extended by approximately 29% to reflect the quality improvement when migrating from NB to WB. This extended $R$ -scale is a "universal" $R$ -scale and it is applicable to both NB and WB transmission channels. + +The primary output of the WB E-model is the transmission rating $R$ . However, the output can also give nominal estimates of user reactions, for instance in the form of MOS values, as described in Annex A. + +# 7 The structure and basic algorithms of the WB E-model + +The WB E-model is based on the equipment impairment factor method, following previous transmission rating models. The reference connection, as shown in Figure 2, is split into a send side + +and a receive side. The model estimates the conversational quality from mouth-to-ear as perceived by the user at the receive side, both as listener and talker. + +![Figure 2 – Reference connection of the WB E-model. This diagram illustrates the transmission path and associated parameters for the WB E-model. It shows a 'Send side' on the left and a 'Receive side' on the right, connected by a central 'Coding/decoding' block. Key parameters include: OLR (Overall Loudness Rating) as the sum of SLR (Send Loudness Rating) and RLR (Receive Loudness Rating); a '0 dBr point' reference; WEPL (Weighted Echo Pass Loss) and Round-trip delay Tr; STMR (Sidetone Masking Rating), LSTR (Listener Speech Transmission Ratio, defined as STMR + Dr), and TELR (Talker Echo Loudness Rating) on the receive side; and various delay and noise parameters like Mean one-way delay T, Absolute delay Ta, Circuit noise Nc, and Packet-loss probability Ppl.](5b4e774d63e0e0ed73801a9247755e5f_img.jpg) + +The diagram shows the reference connection for the WB E-model. On the left, the 'Send side' features a user icon with a 'Ds-factor' and 'Room noise Ps'. A signal path leads to a 'Coding/decoding' block. Above this block is a 'WEPL' and 'Round-trip delay Tr' loop. A '0 dBr point' is marked on the signal path. On the right, the 'Receive side' features another user icon with a 'Dr-factor' and 'Room noise Pr'. The signal path from the coding/decoding block to the receive side includes 'Circuit noise Nc referred to 0 dBr', 'Equipment impairment factor Ie', 'Packet-loss probability Ppl', and 'Packet-loss robustness factor Bpl'. Various delay and rating parameters are indicated with double-headed arrows: 'OLR' (Overall Loudness Rating) spanning both sides; 'SLR' (Send Loudness Rating) on the send side; 'RLR' (Receive Loudness Rating) on the receive side; 'Mean one-way delay T' between the send side and the receive side; 'Absolute delay Ta' between the send side and the receive side; and 'TELR' (Talker Echo Loudness Rating) on the receive side. Other parameters shown include 'Quantizing distortion qdu' and 'Advantage factor A'. The formula 'LSTR = STMR + Dr' is also shown. + +Figure 2 – Reference connection of the WB E-model. This diagram illustrates the transmission path and associated parameters for the WB E-model. It shows a 'Send side' on the left and a 'Receive side' on the right, connected by a central 'Coding/decoding' block. Key parameters include: OLR (Overall Loudness Rating) as the sum of SLR (Send Loudness Rating) and RLR (Receive Loudness Rating); a '0 dBr point' reference; WEPL (Weighted Echo Pass Loss) and Round-trip delay Tr; STMR (Sidetone Masking Rating), LSTR (Listener Speech Transmission Ratio, defined as STMR + Dr), and TELR (Talker Echo Loudness Rating) on the receive side; and various delay and noise parameters like Mean one-way delay T, Absolute delay Ta, Circuit noise Nc, and Packet-loss probability Ppl. + +Figure 2 – Reference connection of the WB E-model + +The transmission parameters used as an input to the computation model are shown in Figure 2. Values for room noise and for the $D$ -factors are handled separately in the algorithm for the send side and receive side and may be of different amounts. The parameters send loudness rating (SLR), receive loudness rating (RLR) and circuit noise $N_c$ are referred to a defined 0 dBr point. All other input parameters are either considered as values for the overall connection, such as overall loudness rating (OLR) (in any case, the sum of SLR and RLR), equipment impairment factors $I_e$ and advantage factor $A$ , or referred to only for the receive side, such as sidetone masking rating (STMR), LSTR, weighted echo pass loss (WEPL) (for calculation of listener echo) and talker echo loudness rating (TELR). + +There are three different parameters associated with transmission time. The absolute delay $T_a$ represents the total one-way delay between the send side and receive side and is used to estimate the impairment due to excessive delay. The parameter mean one-way delay $T$ represents the delay between the receive side (in talking state) and the point in a connection where a signal coupling occurs as a source of echo. The round-trip delay $T_r$ only represents the delay in a 4-wire loop, where the "double reflected" signal will cause impairments due to listener echo. + +Not all parameters listed in Figure 2 are currently used in the WB E-model. However, they are displayed here in order to provide a full description of the transmission channel considering also degradations which might be included in an updated WB E-model at a later stage. The current version is based on [b-Raake-02] and on further extensions for talker echo and delay which have been presented in ITU's Telecommunication Sector (ITU-T). + +## 7.1 Calculation of the transmission rating factor, $R$ + +For WB, the basic E-model formula (7-1 of [ITU-T G.107]) can be re-written as: + +$$R = R_{o, WB} - I_{s, WB} - I_{d, WB} - I_{e, eff, WB} + A \quad (7-1)$$ + +$Ro, WB$ represents in principle the basic signal-to-noise ratio, including noise sources such as circuit noise and room noise. Factor $Is, WB$ is a combination of all impairments which occur more or less simultaneously with the voice signal. Factor $Id, WB$ represents the impairments caused by delay and the effective equipment impairment factor $Ie, eff, WB$ represents impairments caused by low bit-rate codecs. It also includes impairment due to randomly distributed pack losses. The advantage factor $A$ allows for compensation of impairment factors when the user benefits from other types of access. The term $Id, WB$ is subdivided into further specific impairment values. The following clauses give the equations used in the WB E-model. + +## 7.2 Basic signal-to-noise ratio, $Ro, WB$ + +The basic signal-to-noise ratio $Ro, WB$ is defined by: + +$$Ro, WB = 129 \quad (7-2)$$ + +The effects of circuit noise $Nc$ , room noise at send side $Ps$ and room noise at receive side $Pr$ are items for further study. + +## 7.3 Simultaneous impairment factor, $Is, WB$ + +The factor $Is, WB$ is the sum of all impairments which may occur more or less simultaneously with the voice transmission. This aspect has not been analysed for the WB case so far, thus it is set to: + +$$Is, WB = 0 \quad (7-3)$$ + +## 7.4 Delay impairment factor, $Id, WB$ + +$Id, WB$ , the impairment factor representing all impairments due to delay of voice signals, is further divided into the three factors $Idte, WB$ , $Idle, WB$ and $Idd$ : + +$$Id, WB = Idte, WB + Idle, WB + Idd \quad (7-4)$$ + +The factor $Idte, WB$ gives an estimate for the impairments due to talker echo: + +$$Idte, WB = \left[ \frac{Roe - Re, WB}{2} + \sqrt{\frac{(Roe - Re, WB)^2}{4} + 100} - 1 \right] (1 - e^{-T}) \quad (7-5)$$ + +where: + +$$Roe = -1.5(No, WB - RLR) \quad (7-6)$$ + +$$Re, WB = 80 + 3(TERV, WB - 14) \quad (7-7)$$ + +$$TERV, WB = TELR + K - 40 \log \frac{1 + \frac{T}{10}}{1 + \frac{T}{150}} + 6e^{-0.3T^2} \quad (7-8)$$ + +For $T < 100$ ms: + +$$K = 0.08 \cdot T + 10 \quad (7-9)$$ + +For $T \geq 100$ ms: + +$$K = 18 \quad (7-10)$$ + +For the WB case, we currently do not assume any mutual influence between talker echo and sidetone. + +The factor $Idle, WB$ represents impairments due to listener echo. This impairment has not been specifically studied for the WB case, but it is assumed that the degradations will be similar to those of the NB case, so the formulae are congruent with the ones of the NB E-model: + +$$Idle, WB = \frac{Ro, WB - Rle}{2} + \sqrt{\frac{(Ro, WB - Rle)^2}{4} + 169} \quad (7-11)$$ + +where: + +$$Rle = 10.5(WEPL + 7)(Tr + 1)^{-0.25} \quad (7-12)$$ + +The factor $Idd$ represents the impairment caused by an absolute delay $Ta$ that is too long, which occurs even with perfect echo cancelling. + +For $Ta \leq 100$ ms: + +$$Idd = 0$$ + +For $Ta > 100$ ms: + +$$Idd = 25 \cdot 1.29 \left\{ (1 + X^6)^{\frac{1}{6}} - 3 \left( 1 + \left[ \frac{X}{3} \right]^6 \right)^{\frac{1}{6}} + 2 \right\} \quad (7-13)$$ + +with: + +$$X = \frac{\log\left(\frac{Ta}{100}\right)}{\log 2} \quad (7-14)$$ + +## 7.5 Equipment impairment factor, $Ie, WB$ + +The values for the equipment impairment factor $Ie, WB$ of elements using low bit-rate codecs are not related to other input parameters. They depend on subjective MOS test results as well as on network experience. Refer to Appendix IV of [ITU-T G.113] for the currently recommended values of $Ie, WB$ . + +In case of packet-loss, the packet-loss dependent effective equipment impairment factor $Ie, eff, WB$ is derived using the codec-specific value for the equipment impairment factor at zero packet-loss $Ie, WB$ and the packet-loss robustness factor $Bpl$ . With the packet-loss probability $Ppl$ , $Ie, eff, WB$ is calculated using the equation: + +$$Ie, eff, WB = Ie, WB + (95 - Ie, WB) \cdot \frac{Ppl}{Ppl + Bpl} \quad (7-15)$$ + +As can be seen from Equation 7-15, the effective equipment impairment factor in case of $Ppl = 0$ (no packet-loss) is equal to the $Ie, WB$ value defined in Appendix IV of [ITU-T G.113]. + +Corresponding values for $Bpl, wb$ can be found in Appendix IV of [ITU-T G.113]. + +One should derive $Ie, eff, WB$ by using the $Ie, wb$ and $Bpl$ values if they are provided in [ITU-T G.113]. If, for practical reasons, it is difficult to observe the packet-loss rate ( $Ppl$ ), one can use the approach found in [ITU-T P.834.1] to directly derive $Ie, eff, WB$ . + +If $Ie, wb$ is derived directly by using the instrumental method recommended in [ITU-T P.834.1], it already reflects the effect of packet-loss introduced in the preparation of speech materials under test. Therefore, one should not use equation (7-15). Rather, one should use the $Ie, wb$ value derived by [ITU-T P.834.1] in $Ie, eff, WB$ in equation (7-1). + +## 7.6 Advantage factor, $A$ + +Background information on the advantage factor $A$ can be found in Appendix II of [ITU-T G.113]. As this effect has not yet been studied for the WB case, it is recommended to set: + +$$A = 0 \quad (7-16)$$ + +## 7.7 Default values + +For all input parameters used in the algorithm of the E-model, the default values are listed in Table 1. It is strongly recommended to use these default values for all parameters which are not varied during planning calculation. + +**Table 1 – Default values and permitted ranges for the parameters** + +| Parameter | Abbr. | Unit | Default value | Permitted range | Remark | +|-----------------------------------------|--------|-------|---------------|-----------------|--------------| +| Send loudness rating | SLR | dB | +8 | - | (Note 3) | +| Receive loudness rating | RLR | dB | +2 | - | (Note 3) | +| Sidetone masking rating | STMR | dB | 15 | 10 ... 20 | (Note 2) | +| Listener sidetone rating | LSTR | dB | 18 | 13 ... 23 | (Note 2) | +| D-Value of telephone, send side | Ds | – | 3 | - | (Note 3) | +| D-Value of telephone, receive side | Dr | – | 3 | - | (Note 3) | +| Talker echo loudness rating | TELR | dB | 65 | 5 ... 65 | | +| Weighted echo path loss | WEPL | dB | 110 | 5 ... 110 | | +| Mean one-way delay of the echo path | T | ms | 0 | 0 ... 500 | | +| Round-trip delay in a 4-wire loop | Tr | ms | 0 | 0 ... 1000 | | +| Absolute delay in echo-free connections | Ta | ms | 0 | 0 ... 500 | | +| Equipment impairment factor | Ie, WB | – | 0 | 0 ... 56 | (Note 4) | +| Packet-loss robustness factor | Bpl | – | 4.3 | 4.3 ... 7.3 | (Notes 3, 4) | +| Random packet-loss probability | Ppl | % | 0 | 0 ... 20 | (Notes 3, 4) | +| Circuit noise referred to 0 dBr-point | Nc | dBm0p | –70 | - | (Note 3) | +| Noise floor at the receive side | Nfor | dBmp | –96 | – | (Note 3) | +| Room noise at the send side | Ps | dB(A) | 35 | - | (Note 3) | +| Room noise at the receive side | Pr | dB(A) | 35 | - | (Note 3) | +| Advantage factor | A | – | 0 | 0 ... 20 | | + +NOTE 1 – Total values between microphone or receiver and 0 dBr-point. +NOTE 2 – Fixed relation: LSTR = STMR + D. +NOTE 3 – Currently under study. +NOTE 4 – If Ppl > 0%, then the Bpl must match the codec, packet size, and PLC assumed. + +## Annex A + +### MOS values derived from the transmission rating factor $R$ + +(This annex forms an integral part of this Recommendation.) + +The transmission rating factor $R$ can be in the range from 0 to 129, where $R = 0$ represents an extremely bad quality and $R = 129$ represents a very high quality in the WB case. An estimated mean opinion score ( $\text{MOS}_{\text{CQEW}}$ ) for the conversational situation on the scale 1-5 can be obtained from the $R$ -factor by using the equations: + +$$R_x = \frac{R}{1.29} \quad (\text{A-1})$$ + +$$\text{For } R_x < 0: \quad \text{MOS}_{\text{CQEW}} = 1$$ + +$$\text{For } 0 < R_x < 100: \quad \text{MOS}_{\text{CQEW}} = 1 + 0.035 R_x + R_x(R_x - 60)(100 - R_x)7 \cdot 10^{-6} \quad (\text{A-2})$$ + +$$\text{For } R_x > 100: \quad \text{MOS}_{\text{CQEW}} = 4.5$$ + +## Bibliography + +- [b-ITU-T G.108] Recommendation ITU-T G.108 (1999), *Application of the E-model: A planning guide*. +- [b-ITU-T G.108.1] Recommendation ITU-T G.108.1 (2000), *Guidance for assessing conversational speech transmission quality effects not covered by the E-model*. +- [b-ITU-T G.109] Recommendation ITU-T G.109 (1999), *Definition of categories for speech transmission quality*. +- [b-Barriac] Barriac, V., Le Saout, J.-Y., and Lockwood C. (2004), *Discussion on Unified Methodologies for the Comparison of Voice Quality of Narrowband and Wideband Scenarios*, ETSI Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction, pp. 75-79. +- [b-Möller-01] Möller, S. (2000), *Assessment and Prediction of Speech Quality in Telecommunications*, Springer. +- [b-Möller-02] Möller, S., Raake, A., Kitawaki, N., Takahashi, A., Wältermann, M. (2006), *Impairment Factor Framework for Wideband Speech Codecs*, IEEE Trans. Audio, Speech and Language Processing 14(6), pp. 1969-1976. +- [b-Raake-01] Raake, A. (2006), *Speech Quality of VoIP – Assessment and Prediction*, Chichester, UK, Wiley. +- [b-Raake-02] Raake, A., Möller, S., Wältermann, M., Côté, N., Ramirez, J.-P. (2010), *Parameter-based Prediction of Speech Quality in Listening Context – Towards a WB E-Model*, in: Second International Workshop on Quality of Multimedia Experience (QoMEX'10), June 21-23, Trondheim, 182-187. +- [b-Takahashi] Takahashi, A., Kurashima, A., and Yoshino, H. (2005), *Subjective Quality Index for Compatibly Evaluating Narrowband and Wideband Speech*, Prague, Czech Republic, MESAQIN. + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation 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a/marked/G/T-REC-G.1091-201410-I_PDF-E/raw.md b/marked/G/T-REC-G.1091-201410-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..7117057679cdcd6f8112030875ce47bc67baa181 --- /dev/null +++ b/marked/G/T-REC-G.1091-201410-I_PDF-E/raw.md @@ -0,0 +1,479 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.1091** + +(10/2014) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Multimedia Quality of Service and performance – Generic +and user-related aspects + +# --- **Quality of Experience requirements for telepresence services** + +Recommendation ITU-T G.1091 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.1091 + +# Quality of Experience requirements for telepresence services + +## Summary + +Telepresence is an interactive audio-visual communications experience between remote locations, where users enjoy a strong sense of realism and presence between participants by optimizing a variety of attributes such as audio and video quality, eye contact, gaze awareness, body language, spatial audio, coordinated environments and natural image size. In this regard, delivering a high-level of quality of experience (QoE) is an important factor. Recommendation ITU-T G.1091 provides guidelines for achieving high QoE in telepresence services. First, a high-level description of a telepresence system is described, with an overview of important use cases. Then, specific audio and visual parameters, and other characteristics that are important from a QoE perspective are defined. Where possible, specific values for the parameters necessary to achieve high QoE are recommended, along with references to associated test methodologies. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.1091 | 2014-10-29 | 12 | 11.1002/1000/12310 | + +## Keywords + +QoE, telepresence. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2015 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|---------------------------------------------------------------|---| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 1 | +| 3.1 | Terms defined elsewhere ..... | 1 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Conventions ..... | 2 | +| 5.1 | Requirement terminology ..... | 2 | +| 5.2 | Icons used ..... | 2 | +| 6 | High-level QoE considerations for telepresence services ..... | 3 | +| 6.1 | Telepresence system description ..... | 4 | +| 6.2 | Use cases ..... | 4 | +| 7 | Audio characteristics ..... | 5 | +| 7.1 | Send and receive loudness ratings ..... | 5 | +| 7.2 | Send and receive side frequency responses..... | 5 | +| 7.3 | Send and receive side distortion ..... | 6 | +| 7.4 | Send and receive side noise ..... | 6 | +| 7.5 | Directionality of audio (spatial characteristics)..... | 6 | +| 7.6 | Acoustic echo/double talk ..... | 6 | +| 7.7 | Intelligibility of audio..... | 6 | +| 8 | Video characteristics..... | 6 | +| 8.1 | Actual size ..... | 6 | +| 8.2 | Resolution (definition)..... | 6 | +| 8.3 | Image quality ..... | 6 | +| 8.4 | Eye gaze..... | 7 | +| 8.5 | Spatial considerations for video ..... | 7 | +| 9 | Display characteristics ..... | 7 | +| 9.1 | Screen size ..... | 7 | +| 9.2 | Aspect ratios ..... | 7 | +| 9.3 | Continuity across borders ..... | 7 | +| 9.4 | Colour space (4:2:2, 4:2:0, 4:4:4)..... | 7 | +| 9.5 | Colour fidelity ..... | 7 | +| 9.6 | Mirrored image..... | 7 | +| 10 | Audiovisual characteristics ..... | 7 | +| 10.1 | Absolute delay of audio and video streams ..... | 8 | +| 10.2 | Lip sync ..... | 8 | +| 11 | Room characteristics..... | 8 | + +| | Page | +|-------------------------------------------|------| +| 11.1 Background noise ..... | 8 | +| 11.2 Reverberation ..... | 8 | +| 11.3 Lighting ..... | 8 | +| 11.4 Sound uniformity ..... | 8 | +| 11.5 Impact of seating arrangements ..... | 8 | +| 11.6 Temperature ..... | 8 | +| 11.7 Humidity ..... | 8 | +| 11.8 Audibility in local room ..... | 8 | +| 12 Other characteristics ..... | 9 | +| 12.1 Ease of use ..... | 9 | +| Bibliography ..... | 10 | + +# Recommendation ITU-T G.1091 + +# Quality of Experience requirements for telepresence services + +# 1 Scope + +This Recommendation provides guidelines for achieving high quality of experience (QoE) in telepresence services. First, a high-level description of a telepresence system is described, with an overview of important use cases. Then, specific audio and visual parameters, and other characteristics that are important from a QoE perspective are defined. Where possible, specific values for the parameters necessary to achieve high QoE are recommended, along with references to associated test methodologies. The list of parameters and requirements is not to be considered as an exhaustive list, and it is expected that this Recommendation will be updated as more experience is gained with telepresence systems. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T F.734] Recommendation ITU-T F.734 (2014), *Definitions, requirements and use cases for telepresence systems*. +- [ITU-T G.131] Recommendation ITU-T G.131 (2003), *Talker echo and its control*. +- [ITU-T H.420] Recommendation ITU-T H.420 (2014), *Telepresence system architecture*. +- [ITU-T P.300] Recommendation ITU-T P.300 (2001), *Transmission performance of group audio terminals (GATs)*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 actual size** [ITU-T F.734]: A rendered figure in a display is the same size as if the person is in the room. +- 3.1.2 gaze awareness** [ITU-T F.734]: Awareness of gaze direction of persons by watching their eyes, head and body position. There is awareness of both direct gaze and averted gaze. Direct gaze is the perception of persons looking at each other directly and simultaneously. Averted gaze is the perception that other persons are looking at someone/something else in the environment. +- 3.1.3 gaze direction** [ITU-T F.734]: The vector positioned along the visual axis, pointing from the fovea of the looker through the centre of the pupil to the gazed-at spot. +- 3.1.4 eye contact** [ITU-T F.734]: Technically equivalent to a mutual direct-gaze between two persons communicating. +- 3.1.5 render** [b-IETF RFC 7262]: The process of generating a representation from a media, such as displayed motion video or sound emitted from loudspeakers. + +**3.1.6 telepresence** [ITU-T F.734]: An interactive audio-visual communications experience between remote locations, where the users enjoy a strong sense of realism and presence between participants by optimizing a variety of attributes such as audio and video quality, eye contact, gaze awareness, body language, spatial audio, coordinated environments and natural image size. + +**3.1.7 telepresence system** [ITU-T H.420]: A set of functions, devices and network elements which are able to capture, deliver, manage and render multiple high quality interactive audio and video signals in a telepresence conference. An appropriate number of devices (e.g., cameras, screens, loudspeakers, microphones, codecs, multipoint control units, PCs) and environmental characteristics are used to establish telepresence. + +## **3.2 Terms defined in this Recommendation** + +None. + +# **4 Abbreviations and acronyms** + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|------------------------------| +| CRC | Call and Resource Controller | +| GW | Gateway | +| IP | Internet Protocol | +| MCU | Multipoint Control Unit | +| PC | Personal Computer | +| PLMN | Public Land Mobile Network | +| QoE | Quality of Experience | + +# **5 Conventions** + +## **5.1 Requirement terminology** + +In this Recommendation the following conventions are used: + +- "Shall" indicates a mandatory requirement. +- "Should" indicates a suggested but optional course of action. +- "May" indicates an optional course of action rather than a recommendation that something take place. + +## **5.2 Icons used** + +Figure 1 shows the meaning of icons used in this Recommendation. + +![A grid of 28 icons representing various telepresence and network components. The icons are arranged in 7 rows and 4 columns. Row 1: Single-screen telepresence endpoint (one screen with two people), Two-screen telepresence endpoint (two screens, one with two people, one with a bar chart), Three-screen telepresence endpoint (three screens, each with two people), Document camera (a physical camera). Row 2: Gate keeper (a box with two people and a shield), ITU-T H.320 endpoint (a small box labeled 'ITU-T H.320'), Legacy ITU-T H.323 endpoint (a box with a screen), Loudspeaker (a circular speaker). Row 3: Main camera (three camera icons), Management system (a laptop showing a network diagram), Main display (three screens, each with two people), Microphone (a vintage microphone). Row 4: Mobile phone (a mobile phone), Multipoint control unit (a box with three people and arrows), Personal computer (a laptop), Phone (a desktop telephone). Row 5: Presentation display (a monitor labeled 'HDTV'), Router (a circular icon with four arrows), SIP endpoint (a box labeled 'SIP'), Switch (a box with five horizontal lines). Row 6: Telepresence control unit (a box with people and a 'DBS' icon), Telepresence media codec (a box with a vertical bar and arrows), Telepresence media input/output control unit (a box with four arrows in a circle), Telepresence media processor (a box with three horizontal lines and arrows). Row 7: Touch control panel (a hand touching a screen), Video/voice gateway (a circular icon with 'X' and 'V' and arrows). The text 'G.1091(14)_F01' is in the bottom right corner.](fd955384881fd240be5518d3050588d9_img.jpg) + +A grid of 28 icons representing various telepresence and network components. The icons are arranged in 7 rows and 4 columns. Row 1: Single-screen telepresence endpoint (one screen with two people), Two-screen telepresence endpoint (two screens, one with two people, one with a bar chart), Three-screen telepresence endpoint (three screens, each with two people), Document camera (a physical camera). Row 2: Gate keeper (a box with two people and a shield), ITU-T H.320 endpoint (a small box labeled 'ITU-T H.320'), Legacy ITU-T H.323 endpoint (a box with a screen), Loudspeaker (a circular speaker). Row 3: Main camera (three camera icons), Management system (a laptop showing a network diagram), Main display (three screens, each with two people), Microphone (a vintage microphone). Row 4: Mobile phone (a mobile phone), Multipoint control unit (a box with three people and arrows), Personal computer (a laptop), Phone (a desktop telephone). Row 5: Presentation display (a monitor labeled 'HDTV'), Router (a circular icon with four arrows), SIP endpoint (a box labeled 'SIP'), Switch (a box with five horizontal lines). Row 6: Telepresence control unit (a box with people and a 'DBS' icon), Telepresence media codec (a box with a vertical bar and arrows), Telepresence media input/output control unit (a box with four arrows in a circle), Telepresence media processor (a box with three horizontal lines and arrows). Row 7: Touch control panel (a hand touching a screen), Video/voice gateway (a circular icon with 'X' and 'V' and arrows). The text 'G.1091(14)\_F01' is in the bottom right corner. + +**Figure 1 – Icons used in this Recommendation** + +# 6 High-level QoE considerations for telepresence services + +This clause provides a high-level description of telepresence systems. Some scenarios and use cases are also provided to provide a context for assessing the important factors from the point of view of QoE. + +## 6.1 Telepresence system description + +The term "telepresence systems" is used to refer to conferencing systems that provide high definition and high quality audio/video, enabling a "being-there" experience. A telepresence system includes endpoints (both telepresence and legacy), multipoint control unit (MCU), call and resource controller (CRC), gateway (GW), management system, etc., as shown in Figure 2. [ITU-T H.420], "Telepresence System Architecture", provides a detailed description of a telepresence system. + +![Figure 2: High-level telepresence architecture network model. This diagram shows a central cloud labeled 'IP network' connected to various devices. On the left, a 'PLMN' cloud connects to a mobile phone and a desktop phone. A central router connects to a 'SIP' server and an 'ITU-T H.320' gateway. The 'IP network' cloud is also connected to several telepresence endpoints, represented by icons of people and screens. Some endpoints are connected directly to the IP network, while others are connected through intermediate routers or gateways. The diagram illustrates a complex network architecture for telepresence systems.](cfda9df1319e04207eb28bcefd1dab7b_img.jpg) + +Figure 2: High-level telepresence architecture network model. This diagram shows a central cloud labeled 'IP network' connected to various devices. On the left, a 'PLMN' cloud connects to a mobile phone and a desktop phone. A central router connects to a 'SIP' server and an 'ITU-T H.320' gateway. The 'IP network' cloud is also connected to several telepresence endpoints, represented by icons of people and screens. Some endpoints are connected directly to the IP network, while others are connected through intermediate routers or gateways. The diagram illustrates a complex network architecture for telepresence systems. + +**Figure 2 – High-level telepresence architecture network model** + +## 6.2 Use cases + +Clause 6 of [ITU-T F.734], "Definitions, requirements, and use cases for telepresence systems", presents a set of use cases describing typical scenarios. The most common and basic use cases are introduced and illustrated in detail, which are described from the viewpoint of the users. + +### 6.2.1 Use case 1: Symmetric point-to-point meeting + +In this use case, each of the two sites has an identical number of screens, with cameras having fixed fields of view, and one camera for each screen. The number of screens or cameras is not relevant as long as both sites have the same number. The sound type is the same at each end. Figure 3 illustrates the use case. + +![Figure 3: Use case 1: Symmetric point-to-point meeting. This diagram shows two identical 'Two-screen telepresence endpoint' units connected via a central cloud labeled 'IP network'. Each endpoint consists of two screens: one showing two people and the other showing a bar chart. Above each screen is a camera. The endpoints are connected to the IP network cloud, which in turn connects to the other endpoint, illustrating a symmetric point-to-point meeting setup.](54fabc351eda5228d2fa28cd9ba07971_img.jpg) + +Figure 3: Use case 1: Symmetric point-to-point meeting. This diagram shows two identical 'Two-screen telepresence endpoint' units connected via a central cloud labeled 'IP network'. Each endpoint consists of two screens: one showing two people and the other showing a bar chart. Above each screen is a camera. The endpoints are connected to the IP network cloud, which in turn connects to the other endpoint, illustrating a symmetric point-to-point meeting setup. + +**Figure 3 – Use case 1: Symmetric point-to-point meeting** + +For further information, see clause 3.1 of [b-IETF RFC 7205]. + +### 6.2.2 Use case 2: Multipoint meeting + +In this use case of a multipoint telepresence conference, there are more than two sites participating. Figure 4 illustrates the use case. The number of screens or cameras can be different or the same. Each site can have different audio/video characteristics. + +For further information, see clause 3.3 of [b-IETF RFC 7205]. + +![Diagram illustrating Use case 2: Multipoint meeting. A central cloud labeled 'IP network' is connected to three telepresence endpoints. The top-left endpoint is a 'Two-screen telepresence endpoint' with two screens. The top-right endpoint is a 'Three-screen telepresence endpoint' with three screens. The bottom endpoint is also a 'Three-screen telepresence endpoint' with three screens. Each screen displays a person icon, and each endpoint has three camera icons above its screens. The diagram is labeled G.1091(14)_F04 in the bottom right corner.](5a4e62bead259c258d069fd3663ea670_img.jpg) + +Diagram illustrating Use case 2: Multipoint meeting. A central cloud labeled 'IP network' is connected to three telepresence endpoints. The top-left endpoint is a 'Two-screen telepresence endpoint' with two screens. The top-right endpoint is a 'Three-screen telepresence endpoint' with three screens. The bottom endpoint is also a 'Three-screen telepresence endpoint' with three screens. Each screen displays a person icon, and each endpoint has three camera icons above its screens. The diagram is labeled G.1091(14)\_F04 in the bottom right corner. + +Figure 4 – Use case 2: Multipoint meeting + +# 7 Audio characteristics + +This clause describes the audio characteristics related to QoE of telepresence services in more detail. + +## 7.1 Send and receive loudness ratings + +Telepresence systems shall send audio to other telepresence systems with a SendLoudnessRating of $(+13 - F_s)$ dB, measured in accordance with [ITU-T P.300]. + +In order to take into account the difference between the reference test positioning and the actual microphone-talker operating distance ( $d_s$ ), for which the terminal is adjusted, the following correction factor $F_s$ is defined: + +$$F_s[\text{dB}] = 20 \text{ Log} \left( \frac{d_s}{0.5} \right) \quad (d_s \text{ in metres})$$ + +Telepresence systems shall receive audio from other telepresence systems with a nominal Receive Loudness Rating of $(+5 - F_r)$ dB, measured in accordance with [ITU-T P.300]. + +In order to take into account the difference between the reference test positioning and the actual loudspeaker-listener operating distance ( $d_r$ ) for which the terminal is adjusted, the following correction factor $F_r$ is defined: + +$$F_r[\text{dB}] = 20 \text{ Log} \left( \frac{d_r}{0.5} \right) \quad (d_r \text{ in metres})$$ + +## 7.2 Send and receive side frequency responses + +Telepresence systems shall provide audio with send and receive side frequency responses from 100 Hz to 20 kHz. + +## **7.3 Send and receive side distortion** + +Telepresence systems shall provide audio with send and receive side distortion less than 3%. Note, different specifications exist for send and receive. + +For send side distortion the requirement is 2% (1% is a desired objective). + +For received side distortion the requirement is 3%. + +## **7.4 Send and receive side noise** + +Send side noise should be less than –63 dBm0p. Receive side noise should be less than 40 dBA (under maximum volume). + +### **7.5 Directionality of audio (spatial characteristics)** + +In telepresence systems, all the seats shall sense directions (e.g., left, middle, right for three screen telepresence endpoint) for rendering. + +The person who is talking shall be identified in correct spatial geometry. + +## **7.6 Acoustic echo/double talk** + +Single talk: The weighted terminal coupling loss (TCLw) should be greater than or equal to 45 dB. + +Double talk: Talker echo loss rating (TELR, as defined in [ITU-T G.131]) double talk should be greater than 27 dB. + +## **7.7 Intelligibility of audio** + +Telepresence systems shall provide audio with intelligibility greater than 94%. + +# **8 Video characteristics** + +This clause describes the video characteristics related to QoE of telepresence services in more detail. + +## **8.1 Actual size** + +Telepresence systems shall provide an actual-sized video display as far as possible: + +The difference in size between the original and displayed video should be limited within 10% of the original. + +## **8.2 Resolution (definition)** + +Telepresence systems shall provide video with resolution higher than 720 P. + +Telepresence systems shall provide a harmonic view among image displays of different resolutions. + +(One example could be that multiple video captures of different resolutions are to be displayed in one room.) + +## **8.3 Image quality** + +Telepresence systems shall provide images without noticeable geometric distortion. + +The overall geometric distortion should be less than 10%. + +Telepresence systems shall provide images without noticeable noise. + +## **8.4 Eye gaze** + +The remote participants' video images should be rendered within a tolerable angle in both horizontal and vertical axes from the gaze direction between the two communicating participants. The tolerable angles should be 3-5 degrees horizontal and up to 12 degrees upward and 8 degrees downward. + +## **8.5 Spatial considerations for video** + +Telepresence systems shall keep the spatial relationship of video as of physical relationship of participants. + +Sync of videos in different screens should also be considered. + +# **9 Display characteristics** + +This clause describes the display characteristics related to QoE of telepresence services in more detail. In contrast to the video characteristics, displays characteristics focus on physical arrangement for screens, consistency across multiple screens, etc. + +## **9.1 Screen size** + +Ideally, all screens of a telepresence room should be of the same size. However, if different sizes are used in the same room, they should display images for different purposes. + +## **9.2 Aspect ratios** + +Telepresence systems shall provide a harmonized view among screens of different aspect ratios. + +The displayed image size should not differ by more than 5% from the original image size even when different aspect ratios are used. + +## **9.3 Continuity across borders** + +Telepresence systems shall provide a continuous view across frame borders of adjacent screens. + +This is related to clause 9.1 and also illustrated in Figure 10 in clause 7 of [ITU-T F.734]. + +The width of the discontinuous part should be less than 3 cm. + +### **9.4 Colour space (4:2:2, 4:2:0, 4:4:4)** + +Telepresence systems shall provide a harmonized view among displays of different colour spaces. + +## **9.5 Colour fidelity** + +Telepresence systems shall ensure unnoticeable change in displayed colour, especially for skin colour and white balancing. + +## **9.6 Mirrored image** + +Telepresence systems shall not provide mirrored images of participants by default. + +When the local images are displayed on the local screens, it is recommended to provide mirrored images for the participants. + +# **10 Audiovisual characteristics** + +This clause describes the audiovisual characteristics related to QoE of telepresence services in more detail. + +## **10.1 Absolute delay of audio and video streams** + +- For telepresence systems: the end-to-end video delay shall be less than or equal to 320 ms. +- End-to-end audio delay shall be less than or equal to 280 ms. + +## **10.2 Lip sync** + +Audio streams should be less than 40 ms ahead of video streams, or less than 60 ms behind video streams. + +# **11 Room characteristics** + +### **11.1 Background noise** + +Telepresence systems shall enjoy a comfortable environment with background noise less than 40 dBA. + +## **11.2 Reverberation** + +Early reflecting sound should be between 1 kHz and 8 kHz and 15 ms after direct sound should attenuate 10 dB against direct sound. + +## **11.3 Lighting** + +Telepresence systems shall provide a suitable lighting mechanism in the room, which includes but is not limited to, gamut, colour temperature, colour rendering index, type of illumination, etc. + +Telepresence systems should provide a colour temperature of 6'500 K, a luminance of 250 Lux. + +## **11.4 Sound uniformity** + +Telepresence systems shall provide a uniform sound effect (to within 3 dB) for users in the same room. + +## **11.5 Impact of seating arrangements** + +Please note that not all people share the same QoE in the room. + +The maximum QoE difference should be less than 20%. + +### **11.6 Temperature** + +The room temperature should be set between 10~25 C, a suggested temperature is 18 C. + +## **11.7 Humidity** + +The relative humidity should be between 40% and 60%. + +## **11.8 Audibility in local room** + +Audibility for a single word should be greater than or equal to 90%. + +# **12 Other characteristics** + +## **12.1 Ease of use** + +The user interface for frequently used functions shall be optimized. The number of pushes or touches should be no more than five. + +A tutorial should be provided. + +The set-up of a telepresence call shall not exceed seven seconds. + +## Bibliography + +- [b-IETF RFC 7205] IETF RFC 7205 (2014), *Use Cases for Telepresence Multistreams.* +- [b-IETF RFC 7262] IETF RFC 7262 (2014), *Requirements for Telepresence Multistreams.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.114-200305-I_PDF-E/raw.md b/marked/G/T-REC-G.114-200305-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..a3d32e5dbed3e445d4b437b4aa960b4593e80b84 --- /dev/null +++ b/marked/G/T-REC-G.114-200305-I_PDF-E/raw.md @@ -0,0 +1,500 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.114** + +(05/2003) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +International telephone connections and circuits – General +Recommendations on the transmission quality for an +entire international telephone connection + +--- + +**One-way transmission time** + +ITU-T Recommendation G.114 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| General definitions | G.100–G.109 | +| General Recommendations on the transmission quality for an entire international telephone connection | G.110–G.119 | +| General characteristics of national systems forming part of international connections | G.120–G.129 | +| General characteristics of the 4-wire chain formed by the international circuits and national extension circuits | G.130–G.139 | +| General characteristics of the 4-wire chain of international circuits; international transit | G.140–G.149 | +| General characteristics of international telephone circuits and national extension circuits | G.150–G.159 | +| Apparatus associated with long-distance telephone circuits | G.160–G.169 | +| Transmission plan aspects of special circuits and connections using the international telephone connection network | G.170–G.179 | +| Protection and restoration of transmission systems | G.180–G.189 | +| Software tools for transmission systems | G.190–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.114** + +# **One-way transmission time** + +## **Summary** + +This Recommendation provides guidance on the effect of end-to-end one-way delay (sometimes termed latency), and an upper bound one-way network delay. + +While it is recommended that a one-way delay of 400 ms should not be exceeded for general network planning, it is important to appreciate that highly interactive tasks (e.g., many voice calls, interactive data applications, video conferencing) can be affected by much lower delays. + +The effects of delays below 500 ms on conversational speech are estimated using a curve derived from the E-model (ITU-T Rec. G.107). + +This version constitutes a major revision of this Recommendation in order to align with other ITU-T Recommendations of the G.100 series. + +###### **Source** + +ITU-T Recommendation G.114 was approved by ITU-T Study Group 12 (2001-2004) under the ITU-T Recommendation A.8 procedure on 6 May 2003. It includes the modifications introduced by ITU-T Rec. G.114 (2003) Appendix II approved on 30 September 2003. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2003 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +| | Page | +|---------------------------------------------------------------------------------|------| +| 1 Introduction ..... | 1 | +| 2 References..... | 1 | +| 3 Applicability to speech transmission quality – Use of the E-model..... | 2 | +| 4 Recommendations for one-way transmission time..... | 2 | +| 5 Estimating end-to-end delay based on assemblies of transmission elements..... | 3 | +| Annex A – End-to-end delay estimation..... | 4 | +| A.1 Planning values for the delay of transmission elements..... | 4 | +| A.2 Codec delay ..... | 5 | +| A.3 Delay due to IP delay variation buffer ..... | 7 | +| Appendix I – Delay introduced by coder-related processing..... | 8 | +| Appendix II – Guidance on one-way delay for voice over IP ..... | 12 | +| II.1 Introduction ..... | 12 | +| II.2 Achieving satisfactory delay ..... | 12 | + + + +# One-way transmission time + +# 1 Introduction + +This Recommendation provides guidance on the effect of end-to-end one-way delay (sometimes termed latency), and an upper bound on one-way network delay. The effect of delay on speech transmission quality can be estimated by the use of a curve derived from the Transmission Rating Model of ITU-T Rec. G.107 [3], which is the recommended ITU-T method for end-to-end speech transmission planning. ITU-T Rec. G.108 [4] gives detailed examples on how to use the model to assess the transmission performance of connections involving various impairments, including one-way delay; and ITU-T Rec. G.109 [5] maps transmission rating predictions of the model into categories of speech transmission quality. Thus, while ITU-T Rec. G.114 provides useful information regarding one-way delay as a parameter by itself, ITU-T Rec. G.107 [3] (and its ITU-T Rec. G.108 [4] and ITU-T Rec. G.109 [5] companions) should be used to assess the effects of delay in conjunction with other impairments (e.g., distortions due to speech processing). + +Highly interactive tasks (e.g., some speech, video conferencing and interactive data applications) may be affected by delays below 100 ms, as per test result documented in Annex B of previous versions of ITU-T Rec. G.114. For this reason, previous versions of this Recommendation noted that if delays were kept below 150 ms, then most *applications* would not be significantly affected. Additionally, an upper limit of 400 ms for *network* planning purposes was always a part of ITU-T Rec. G.114. However, this parallel treatment of network delays on one hand, with application ("mouth-to-ear") level delays on the other hand, led to confusion in how ITU-T Rec. G.114 should be applied. + +Fortunately, with the development and approval of the E-model (ITU-T Rec. G.107 [3]), which is based on subjective tests of delay (among other parameters), there now exists an agreed way of estimating the effects of delay on mouth-to-ear speech transmission quality. + +Accordingly, simple and straightforward guidance can now be provided for the effects of delay on speech transmission and is given in the present Recommendation. + +The lack of similar tools for non-speech applications is a subject for further study, so this Recommendation can only provide general planning guidance. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [1] ITU-T Recommendation G.100 (2001), *Definitions used in Recommendations on general characteristics of international telephone connections and circuits*. +- [2] ITU-T Recommendation G.101 (1996), *The transmission plan*. +- [3] ITU-T Recommendation G.107 (2003), *The E-Model, a computational model for use in transmission planning*. +- [4] ITU-T Recommendation G.108 (1999), *Application of the E-model: A planning guide*. + +- [5] ITU-T Recommendation G.109 (1999), *Definition of categories of speech transmission quality*. +- [6] ITU-T Recommendation G.131 (1996), *Control of talker echo*. +- [7] ITU-T Recommendation G.168 (2002), *Digital network echo cancellers*. +- [8] ITU-T Recommendation G.763 (1998), *Digital circuit multiplication equipment using G.726 ADPCM and digital speech interpolation*. +- [9] ITU-T Recommendation G.764 (1990), *Voice packetization – Packetized voice protocols*. +- [10] ITU-T Recommendation G.766 (1996), *Facsimile demodulation/remodulation for digital circuit multiplication equipment*. +- [11] ITU-T Recommendation G.767 (1998), *Digital circuit multiplication equipment using 16 kbit/s LD-CELP, digital speech interpolation and facsimile demodulation/remodulation*. +- [12] ITU-T Recommendation Q.551 (2002), *Transmission characteristics of digital exchanges*. +- [13] ITU-T Recommendation Y.1541 (2002), *Network performance objectives for IP-based services*. + +# 3 Applicability to speech transmission quality – Use of the E-model + +This Recommendation provides end-to-end limits for mean one-way delay, independent of other transmission impairments. The need to consider the combined effects of all impairments on speech transmission quality is addressed by the Transmission Rating Model of ITU-T Rec. G.107 [3], which is the recommended ITU-T method for end-to-end speech transmission planning. ITU-T Rec. G.108 [4] gives detailed examples on how to use the model to assess the transmission performance of connections involving various impairments, including delay; and ITU-T Rec. G.109 [5] maps transmission rating predictions of the model into categories of speech transmission quality. Thus, while this Recommendation provides useful information regarding mean one-way delay as a parameter by itself, ITU-T Rec. G.107 [3] (and its ITU-T Rec. G.108 [4] and ITU-T Rec. G.109 [5] companions) should be used to assess the effects of delay in conjunction with other impairments (e.g., distortions due to speech processing). + +# 4 Recommendations for one-way transmission time + +Regardless of the type of application, it is recommended to not exceed a one-way delay of 400 ms for general network planning (i.e., UNI to UNI, as illustrated, for example, in ITU-T Rec. Y.1541 [13]), a value that allows flexibility in deploying global networks, without making an excessive number of user experiences unacceptable. + +However, it is desirable to keep the delays seen by user applications as low as possible. The E-model should be used to estimate the effect of one-way delay (including all delay sources, i.e., "mouth-to-ear") on speech transmission quality for conversational speech as shown below. For non-speech applications such as interactive data or video, there are no agreed-upon assessment tools like the E-model, so the effects of delay on such applications must be carefully monitored. Although a few applications may be slightly affected by end-to-end (i.e., "mouth-to-ear" in the case of speech) delays of less than 150 ms, if delays can be kept below this figure, most applications, both speech and non-speech, will experience essentially transparent interactivity. + +While delays above 400 ms are unacceptable for general network planning purposes, it is recognized that in some exceptional cases this limit will be exceeded. An example of such an exception is an unavoidable double satellite hop for a hard-to-reach location, the impact of which can be estimated by use of the advantage factor in the E-model. + +Regarding the use of the E-model for speech applications, the effect of delay can be seen in the following graph of Transmission Rating, $R$ , versus delay. Also shown are the speech quality categories of ITU-T Rec. G.109 [5], which translate the $R$ values to levels of user acceptance. + +![Figure 1/G.114: Determination of the effects of absolute delay by the E-model. The graph plots the E-model rating R (y-axis, 50 to 100) against Mouth-to-ear-delay/ms (x-axis, 0 to 500). The curve starts at R ≈ 94 for 0 ms delay and decreases as delay increases. The graph is divided into five horizontal color-coded regions representing user satisfaction levels: 'Users very satisfied' (green, R ≈ 94-100), 'Users satisfied' (light green, R ≈ 90-94), 'Some users dissatisfied' (yellow, R ≈ 80-90), 'Many users dissatisfied' (pink, R ≈ 70-80), and 'Nearly all users dissatisfied' (red, R ≈ 50-70). The curve crosses the boundaries between these regions at approximately 150 ms, 250 ms, 350 ms, and 450 ms. Beyond 500 ms, the curve continues as a dashed line. The label 'G.114_F01' is in the bottom right corner.](b93cbfb52e37619e688175a6aad9edd9_img.jpg) + +Figure 1/G.114: Determination of the effects of absolute delay by the E-model. The graph plots the E-model rating R (y-axis, 50 to 100) against Mouth-to-ear-delay/ms (x-axis, 0 to 500). The curve starts at R ≈ 94 for 0 ms delay and decreases as delay increases. The graph is divided into five horizontal color-coded regions representing user satisfaction levels: 'Users very satisfied' (green, R ≈ 94-100), 'Users satisfied' (light green, R ≈ 90-94), 'Some users dissatisfied' (yellow, R ≈ 80-90), 'Many users dissatisfied' (pink, R ≈ 70-80), and 'Nearly all users dissatisfied' (red, R ≈ 50-70). The curve crosses the boundaries between these regions at approximately 150 ms, 250 ms, 350 ms, and 450 ms. Beyond 500 ms, the curve continues as a dashed line. The label 'G.114\_F01' is in the bottom right corner. + +**Figure 1/G.114 – Determination of the effects of absolute delay by the E-model** + +NOTE 1 – The curve in Figure 1 is based on the effect of pure delay only, i.e., in the complete absence of any echo. This is calculated by setting the G.107 E-model parameter $T_a$ equal to the total value of one-way delay from mouth-to-ear, with all other E-model input parameter values set to their default values. The effect of echo, as would be incurred due to imperfect echo control, will result in lower speech quality for a given value of one-way delay. + +NOTE 2 – The calculation also assumes an Equipment Impairment Factor ( $I_e$ ) of zero. Non-zero values, as would be incurred due to speech coding/processing, will result in lower speech quality for a given value of one-way delay. + +NOTE 3 – For one-way delay values exceeding 500 ms, the graph is continued as a dashed line to indicate that these results are not fully validated, but is the best estimate of what should be expected, and, therefore, provides useful guidance. + +# 5 Estimating end-to-end delay based on assemblies of transmission elements + +The nominal delay values and general planning rules given in Annex A, and the coder-related delays of Appendix I, may be used to estimate the total end-to-end transmission time. + +## Annex A + +### End-to-end delay estimation + +### A.1 Planning values for the delay of transmission elements + +**Table A.1/G.114 – Planning values for the delay of transmission elements** + +| Transmission or processing system | Contribution to one-way transmission time | Remarks | +|-------------------------------------------------------------------------------------------------------------------|-------------------------------------------|-----------------------------------------------------------------------| +| Terrestrial coaxial cable or radio-relay system: FDM and digital transmission | 4 µs/km | Allows for delay in repeaters and regenerators | +| Optical fibre cable system, digital transmission | 5 µs/km (Note 1) | | +| Submarine coaxial cable system | 6 µs/km | | +| Submarine optical fibre system:
– transmit terminal
– receive terminal | 13 ms
10 ms | Worst case | +| Satellite system:
– 400 km altitude
– 14 000 km altitude
– 36 000 km altitude | 12 ms
110 ms
260 ms | | +| FDM channel modulator or demodulator | 0.75 ms (Note 2) | | +| PLMS (Public Land Mobile System)
– objective 40 ms | 80-110 ms | | +| H.260-series video coders and decoders | Further study (Note 3) | | +| DCME (ITU-T Rec. G.763 [8]) per pair: for speech, VBD, and non-remodulated fax | 30 ms | Half the sum of transmission times in both directions of transmission | +| DCME (ITU-T Rec. G.767 [11]) per pair: for speech, VBD, and non-remodulated fax | 30 ms | | +| DCME (ITU-T Rec. G.766 [10] in conjunction with ITU-T Recs G.763 [8] or G.767 [11]) per pair: for remodulated fax | 200 ms | | +| PCME (ITU-T Rec. G.764 [9]) per pair:
– with speech and non-remodulated VBD
– with remodulated VBD | 35 ms
70 ms | | +| Transmultiplexer | 1.5 ms (Note 4) | Half the sum of transmission times in both directions of transmission | +| Digital transit exchange, digital-digital | 0.45 ms (Note 5) | | +| Digital local exchange, analogue-analogue | 1.5 ms (Note 5) | | +| Digital local exchange, analogue subscriber line-digital junction | 0.975 ms (Note 5) | | +| Digital local exchange, digital subscriber line-digital junction | 0.825 ms (Note 5) | | +| Echo cancellers | 0.5 ms (Note 6) | | +| ATM (CBR using AAL 1) | 6.0 ms (Note 7) | | + +**Table A.1/G.114 – Planning values for the delay of transmission elements** + +NOTE 1 – This value is provisional and is under study. + +NOTE 2 – These values allow for group-delay distortion around frequencies of peak speech energy and for delay of intermediate higher order multiplex and through-connecting equipment. + +NOTE 3 – Further study required. Delay for these devices is usually non-constant, and the range varies by implementation. Current implementations are of the order of several hundred milliseconds, and considerable delay is added to audio channels to achieve lip-synchronization. Manufacturers are encouraged to reduce their contribution to transmission time, in accordance with this Recommendation. + +NOTE 4 – For satellite digital communications where the transmultiplexer is located at the earth station, this value may be increased to 3.3 ms. + +NOTE 5 – These are mean values: depending on traffic loading, higher values can be encountered, e.g., 0.75 ms (1.950 ms, 1.350 ms, or 1.250 ms) with 0.95 probability of not exceeding. (For details see ITU-T Rec. Q.551 [12].) + +NOTE 6 – This is averaged for both directions of transmission. + +NOTE 7 – This is the cell formation delay of 64 kbit/s stream when it completely fills the cell (one voice channel per VC). In practical applications, additional delay will result, e.g., from cell loss detection and buffering. Other delays may be applicable to other AALs and cell mapping arrangements, and are for further study. + +### **A.2 Codec delay** + +Modern speech codecs operate on collections of speech samples known as frames. Each block of input speech samples is processed into a compressed frame. The coded speech frame is not generated until all speech samples in the input block have been collected by the encoder. Thus, there is a delay of one frame before processing can begin. In addition, many coders also look into the succeeding frame to improve compression efficiency. The length of this advance look is known as the look-ahead time of the coder. The time required to process an input frame is assumed to be the same as the frame length since efficient use of processor resources will be accomplished when an encoder/decoder pair (or multiple encoder/decoder pairs operating in parallel on multiple input streams) fully uses the available processing power (evenly distributed in the time domain). Thus, the delay through an encoder/decoder pair is normally assumed to be: + +$$2 \times \text{frame size} + \text{look-ahead}$$ + +#### **A.2.1 Delay in wirebound environment** + +If the output facility is running at the same rate as the speech codec (e.g., an 8 kbit/s facility for ITU-T Rec. G.729), then an additional frame of delay is incurred when clocking the compressed frame to the facility. Thus, the maximum delay attributable to codec-related processing in conventional wirebound systems (i.e., the PSTN) is: + +$$3 \times \text{frame size} + \text{look-ahead}$$ + +#### **A.2.2 Delay in mobile and wireless environment** + +If the output facility is a mobile network or a cordless facility, then the frame output by the encoder will function similar to the operation in wirebound environment but an additional delay is incurred for attaching the compressed frame to the airpath (assumed again that the mobile facility is running at the same rate as the speech codec). Thus, the maximum delay attributable to codec-related processing in mobile and wireless systems is: + +$$3 \times \text{frame size} + \text{look-ahead} + \text{air interface framing}$$ + +#### **A.2.3 Delay in IP environment (one frame per packet)** + +If the output facility is an IP network, then the frame output by the encoder will instantaneously be dropped into an IP packet. The additional delay required for IP packet assembly and presentation to the underlying link layer will depend on the link layer. When the link layer is a LAN (e.g., Ethernet), this additional time will usually be quite small. Thus, the minimum delay attributable to codec-related processing in IP-based systems is: + +$$2 \times \text{frame size} + \text{look-ahead}$$ + +When the link layer is one with lower clock rate (e.g., Modem connection) or one with high traffic load (e.g., congested LAN), the additional delay will increase substantially. In order to clock compressed frames at least with the same rate to the facility as the speech samples are collected at the input of the encoder, the additional delay should not exceed one frame size. Thus, the maximum delay attributable to codec-related processing in IP-based systems operating in real-time is: + +$$3 \times \text{frame size} + \text{look-ahead}$$ + +#### **A.2.4 Delay in IP environment (multiple frames per packet)** + +If multiple voice frames are grouped together into a single IP packet, further delay is added to the speech signal. This delay will be at least the duration of one extra voice frame at the encoder for each additional voice frame added to the IP packet. Thus, the minimum delay attributable to codec-related processing in IP-based systems with multiple frames per packet is: + +$$(N + 1) \times \text{frame size} + \text{look-ahead}$$ + +where N is the number of frames in each packet. + +When the link layer is one with lower clock rate (e.g., Modem connection) or one with high traffic load (e.g., congested LAN), additional delay will be incurred in delivering the packet to the facility. In order to clock compressed frames at least with the same rate to the facility as the speech samples are collected at the input of the encoder, the additional delay should, in case of multiple frames per packet, not exceed the length of the frames contained in one packet. It should be noted that clocking out a packet to the IP facility cannot start before all speech frames for this packet are available. Thus, the maximum delay attributable to codec-related processing in IP-based systems operating in real-time with multiple frames per packet is: + +$$(2N + 1) \times \text{frame size} + \text{look-ahead}$$ + +where N is the number of frames in each packet. + +The Figure A.1 provides an example for $N = 2$ : + +![Figure A.1/G.114 – Example: Composition of total codec-related delay in an IP Environment for N = 2. The diagram shows a sequence of events on a timeline, with horizontal arrows indicating durations. The events are: 1. collection of speech samples for frame #1; 2. look ahead; 3. processing of speech samples for frame #1; 4. collection of speech samples for frame #2; 5. look ahead; 6. processing of speech samples for frame #2; 7. clocking out a packet with two speech frames to the IP facility; 8. minimum delay to be attributed to the codec; 9. maximum delay to be attributed to the codec. The label G.114_FA.1 is at the bottom right.](4e4be0bd8b235167902f2c03e41da651_img.jpg) + +collection of speech samples for frame #1 + +look ahead + +processing of speech samples for frame #1 + +collection of speech samples for frame #2 + +look ahead + +processing of speech samples for frame #2 + +clocking out a packet with two speech frames to the IP facility + +minimum delay to be attributed to the codec + +maximum delay to be attributed to the codec + +G.114\_FA.1 + +Figure A.1/G.114 – Example: Composition of total codec-related delay in an IP Environment for N = 2. The diagram shows a sequence of events on a timeline, with horizontal arrows indicating durations. The events are: 1. collection of speech samples for frame #1; 2. look ahead; 3. processing of speech samples for frame #1; 4. collection of speech samples for frame #2; 5. look ahead; 6. processing of speech samples for frame #2; 7. clocking out a packet with two speech frames to the IP facility; 8. minimum delay to be attributed to the codec; 9. maximum delay to be attributed to the codec. The label G.114\_FA.1 is at the bottom right. + +**Figure A.1/G.114 – Example: Composition of total codec-related delay in an IP Environment for $N = 2$** + +### A.3 Delay due to IP delay variation buffer + +Packetized transmission systems exhibit variable delay (jitter) in packet delivery time. This is caused by the fact that different packets carrying speech samples of the same telephone conversation may encounter varying queue lengths, or different routes through the network. Details of this effect depend strongly on the specific mechanisms for transport, queuing or prioritization, which may be implemented in such a system. Nevertheless, delay variation must be removed prior to replaying the speech to the user, otherwise significant degradation will be noticeable. + +This is typically achieved by collecting packets in a de-jitter buffer at the receive side. This buffer rearranges the timely order of the packets, and is sized to take into account a certain range of network delay variation, effectively delaying all packets to correspond to the delay of the packet with the longest tolerable transit time. If the delivery time of a packet exceeds the length of the receive buffer, then this packet "arrives too late" with respect to its intended play-out time, and will be discarded. Consequently, the speech carried in this packet is lost for the decoding process. This "packet loss" impairs speech transmission quality (see ITU-T Rec. G.113). + +The contribution of the de-jitter buffer to one-way delay is based on the average time packets spend in the buffer, which is less than the peak buffer size. Depending on the specific type of implementation, as well as on the proper adjustment of the de-jitter buffer, this may be as low as one half of the peak buffer size (assuming symmetrically distributed delays). Packets that encounter the minimum transfer delay will wait the maximum time in the de-jitter buffer before being played out as a synchronous stream, while the reverse is true for packets with the maximum accommodated transfer delay (these packets spend the minimum time in the de-jitter buffer). For PLANNING PURPOSES, IT IS RECOMMENDED to assume that, a de-jitter buffer adds one half of its peak delay to the mean network delay. + +*Example* (taken from Appendix III/Y.1541 [13]): + +A jitter buffer designed to compensate for 50 ms packet delay variation range will introduce 25 ms additional delay, on average. + +Further Guidance on the effects of packet delay, as caused by de-jitter buffer, is provided by ITU-T Rec. Y.1541 [13]. + +It should be noted that, with the use of dynamic de-jitter buffer implementations, the delay of the speech replayed to the user will be subjected to infrequent transitional delay variations when the de-jitter buffer resizes. + +## Appendix I + +## Delay introduced by coder-related processing + +**Table I.1/G.114 – Delay values for coders in wirebound applications** + +| Coder type | Rate (kbit/s) | Frame size (ms) | Look-ahead (ms) | Mean one-way delay introduced by coder-related processing (ms) | Reference | +|------------|---------------|-----------------|-----------------|----------------------------------------------------------------|---------------------------| +| PCM | 64 | 0.125 | 0 | 0.375 | G.711, G.712 | +| ADPCM | 40 | 0.125 | 0 | 0.375 | G.726, G.727 | +| ADPCM | 32 | 0.125 | 0 | 0.375 | G.721(1988), G.726, G.727 | +| ADPCM | 24 | 0.125 | 0 | 0.375 | G.726, G.727 | +| ADPCM | 16 | 0.125 | 0 | 0.375 | G.726, G.727 | +| LD-CELP | 16 | 0.625 | 0 | 1.875 | G.728 | +| LD-CELP | 12.8 | 0.625 | 0 | 1.875 | G.728 | +| CS-ACELP | 8 | 10 | 5 | 35 | G.729 | +| VSELP | 7.95 | 20 | 0 | 60 | IS-54-B, TTA | +| ACELP | 7.4 | 20 | 5 | 65 | IS-641, TTA | +| QCELP | 8 | 20 | 0 | 60 | IS-96-A | +| RCELP | 8 | 20 | 10 | 70 | IS-127 | +| VSELP | 6.7 | 20 | 5 | 65 | Japanese PDC | +| RPE-LTP | 13 | 20 | 0 | 60 | GSM 06.10, Full-rate | +| VSELP | 5.6 | 20 | 0 | 60 | GSM 06.20, Half-rate | +| ACELP | 12.2 | 20 | 0 | 60 | GSM 06.60, Enhanced FR | +| ACELP | 5.3 | 30 | 7.5 | 97.5 | G.723.1 | +| MP-MLQ | 6.3 | 30 | 7.5 | 97.5 | G.723.1 | + +NOTE 1 – The PCM coder converts from analogue to digital and vice-versa while all other coders refer to the PCM domain; for PCM in the analogue domain, additional delay is incurred (0.375 ms). + +NOTE 2 – For wirebound applications, the mean one-way delay introduced by codec-related processing = $3 \times \text{frame size} + \text{look-ahead}$ (see A.2.1). + +**Table I.2/G.114 – Delay values for coders in mobile or cordless applications** + +| Coder type | Rate (kbit/s) | Frame size (ms) | Look-ahead (ms) | Air interface framing (ms) | Mean one-way delay introduced by coder-related processing (ms) | Reference | +|------------|---------------|-----------------|-----------------|----------------------------|----------------------------------------------------------------|---------------------------------| +| PCM | 64 | 0.125 | 0 | (See Note 3) | | G.711, G.712 | +| ADPCM | 40 | 0.125 | 0 | (See Note 3) | | G.726, G.727 | +| ADPCM | 32 | 0.125 | 0 | 13.625 | 14 | G.721(1988), G.726, G.727, DECT | +| ADPCM | 24 | 0.125 | 0 | (See Note 3) | | G.726, G.727 | +| ADPCM | 16 | 0.125 | 0 | (See Note 3) | | G.726, G.727 | +| LD-CELP | 16 | 0.625 | 0 | (See Note 3) | | G.728 | +| LD-CELP | 12.8 | 0.625 | 0 | (See Note 3) | | G.728 | +| CS-ACELP | 8 | 10 | 5 | (See Note 3) | | G.729 | +| VSELP | 7.95 | 20 | 0 | | | IS-54-B, TIA | +| ACELP | 7.4 | 20 | 5 | | | IS-641, TIA | +| QCELP | 8 | 20 | 0 | | | IS-96-A | +| RCELP | 8 | 20 | 10 | | | IS-127 | +| VSELP | 6.7 | 20 | 5 | | | Japanese PDC | +| RPE-LTP | 13 | 20 | 0 | 35 | 95 | GSM 06.10, Full-rate | +| VSELP | 5.6 | 20 | 0 | 35 | 95 | GSM 06.20, Half-rate | +| ACELP | 12.2 | 20 | 0 | 35 | 95 | GSM 06.60, Enhanced FR | +| ACELP | 5.3 | 30 | 7.5 | (See Note 3) | | G.723.1 | +| MP-MLQ | 6.3 | 30 | 7.5 | (See Note 3) | | G.723.1 | + +NOTE 1 – The PCM coder converts from analogue to digital and vice-versa while all other coders refer to the PCM domain; for PCM in the analogue domain, additional delay is incurred (0.375 ms). + +NOTE 2 – For mobile or cordless applications the mean one-way delay introduced by codec-related processing = $3 \times \text{frame size} + \text{look-ahead} + \text{air interface framing}$ (see A.2.2) + +NOTE 3 – For the marked types of coders, Study Group 12 is not aware of any mobile or cordless application. + +**Table I.3/G.114 – Delay values for coders in IP-based applications +(one frame per packet)** + +| Coder type | Rate (kbit/s) | Frame size (ms) | Look-ahead (ms) | Mean one-way delay introduced by coder-related processing (ms) (see Note 2) | | Reference | +|------------|---------------|-----------------|-----------------|-----------------------------------------------------------------------------|---------|---------------------------| +| | | | | Minimum | Maximum | | +| PCM | 64 | 0.125 | 0 | 0.25 | 0.375 | G.711, G.712 | +| ADPCM | 40 | 0.125 | 0 | 0.25 | 0.375 | G.726, G.727 | +| ADPCM | 32 | 0.125 | 0 | 0.25 | 0.375 | G.721(1988), G.726, G.727 | +| ADPCM | 24 | 0.125 | 0 | 0.25 | 0.375 | G.726, G.727 | +| ADPCM | 16 | 0.125 | 0 | 0.25 | 0.375 | G.726, G.727 | +| LD-CELP | 16 | 0.625 | 0 | 1.25 | 1.875 | G.728 | +| LD-CELP | 12.8 | 0.625 | 0 | 1.25 | 1.875 | G.728 | +| CS-ACELP | 8 | 10 | 5 | 25 | 35 | G.729 | +| VSELP | 7.95 | 20 | 0 | 40 | 60 | IS-54-B, TIA | +| ACELP | 7.4 | 20 | 5 | 45 | 65 | IS-641, TIA | +| QCELP | 8 | 20 | 0 | 40 | 60 | IS-96-A | +| RCELP | 8 | 20 | 10 | 50 | 70 | IS-127 | +| VSELP | 6.7 | 20 | 5 | 45 | 65 | Japanese PDC | +| RPE-LTP | 13 | 20 | 0 | 40 | 60 | GSM 06.10, Full-rate | +| VSELP | 5.6 | 20 | 0 | 40 | 60 | GSM 06.20, Half-rate | +| ACELP | 12.2 | 20 | 0 | 40 | 60 | GSM 06.60, Enhanced FR | +| ACELP | 5.3 | 30 | 7.5 | 67.5 | 97.5 | G.723.1 | +| MP-MLQ | 6.3 | 30 | 7.5 | 67.5 | 97.5 | G.723.1 | + +NOTE 1 – The PCM codec converts from analogue to digital and vice-versa while all other coders refer to the PCM domain; for PCM in the analogue domain, additional delay is incurred (0.375 ms). + +NOTE 2 – For IP-related applications, the mean one-way delay introduced by codec-related processing: + $= 2 \times \text{frame size} + \text{look-ahead}$ (minimum, see A.2.3) + $= 3 \times \text{frame size} + \text{look-ahead}$ (maximum, see A.2.3). + +**Table I.4/G.114 – Delay values for coders in IP-based applications +(multiple frames per packet)** + +| Coder type | Rate (kbit/s) | Frame size (ms) | Look-ahead (ms) | Mean one-way delay introduced by coder-related processing (ms) (see Note 2) | | Reference | +|------------|---------------|-----------------|-----------------|-----------------------------------------------------------------------------|----------------------------|---------------------------| +| | | | | Minimum | Maximum | | +| PCM | 64 | 0.125 | 0 | $(N + 1) \times 0.125$ | $(2N + 1) \times 0.125$ | G.711, G.712 | +| ADPCM | 40 | 0.125 | 0 | $(N + 1) \times 0.125$ | $(2N + 1) \times 0.125$ | G.726, G.727 | +| ADPCM | 32 | 0.125 | 0 | $(N + 1) \times 0.125$ | $(2N + 1) \times 0.125$ | G.721(1988), G.726, G.727 | +| ADPCM | 24 | 0.125 | 0 | $(N + 1) \times 0.125$ | $(2N + 1) \times 0.125$ | G.726, G.727 | +| ADPCM | 16 | 0.125 | 0 | $(N + 1) \times 0.125$ | $(2N + 1) \times 0.125$ | G.726, G.727 | +| LD-CELP | 16 | 0.625 | 0 | $(N + 1) \times 0.625$ | $(2N + 1) \times 0.625$ | G.728 | +| LD-CELP | 12.8 | 0.625 | 0 | $(N + 1) \times 0.625$ | $(2N + 1) \times 0.625$ | G.728 | +| CS-ACELP | 8 | 10 | 5 | $(N + 1) \times 10 + 5$ | $(2N + 1) \times 10 + 5$ | G.729 | +| VSELP | 7.95 | 20 | 0 | $(N + 1) \times 20$ | $(2N + 1) \times 20$ | IS-54-B, TIA | +| ACELP | 7.4 | 20 | 5 | $(N + 1) \times 20 + 5$ | $(2N + 1) \times 20 + 5$ | IS-641, TIA | +| QCELP | 8 | 20 | 0 | $(N + 1) \times 20$ | $(2N + 1) \times 20$ | IS-96-A | +| RCELP | 8 | 20 | 10 | $(N + 1) \times 20 + 10$ | $(2N + 1) \times 20 + 10$ | IS-127 | +| VSELP | 6,7 | 20 | 5 | $(N + 1) \times 20 + 5$ | $(2N + 1) \times 20 + 5$ | Japanese PDC | +| RPE-LTP | 13 | 20 | 0 | $(N + 1) \times 20$ | $(2N + 1) \times 20$ | GSM 06.10, Full-rate | +| VSELP | 5.6 | 20 | 0 | $(N + 1) \times 20$ | $(2N+1) \times 20$ | GSM 06.20, Half-rate | +| ACELP | 12.2 | 20 | 0 | $(N + 1) \times 20$ | $(2N + 1) \times 20$ | GSM 06.60, Enhanced FR | +| ACELP | 5.3 | 30 | 7.5 | $(N + 1) \times 30 + 7.5$ | $(2N + 1) \times 30 + 7.5$ | G.723.1 | +| MP-MLQ | 6.3 | 30 | 7.5 | $(N + 1) \times 30 + 7.5$ | $(2N + 1) \times 30 + 7.5$ | G.723.1 | + +NOTE 1 – The PCM codec converts from analogue to digital and vice-versa while all other coders refer to the PCM domain; for PCM in the analogue domain, additional delay is incurred (0.375 ms). + +NOTE 2 – For IP-related applications with multiple frames per packet, the mean one-way delay introduced by codec-related processing can be calculated as follows: + +$= (N + 1) \times \text{frame size} + \text{look-ahead}$ (minimum, see A.2.4) + +$= (2N + 1) \times \text{frame size} + \text{look-ahead}$ (maximum, see A.2.4). + +NOTE 3 – N = number of frames per packet. + +## Appendix II + +## Guidance on one-way delay for voice over IP + +### II.1 Introduction + +This appendix gives additional guidance on the application of ITU-T Rec. G.114. The main purpose is to provide practical information for end-to-end VoIP network planning. Also, this appendix provides a linkage to the IP network delay objectives in ITU-T Rec. Y.1541. + +### II.2 Achieving satisfactory delay + +For many *intra-regional* (e.g., within Africa, Europe, North America) routes in the range of 5000 km or less, users of VoIP connections are likely to experience mouth-to-ear delays <150 ms. Appendix III/Y.1541 illustrates this calculation using reference terminals with a total of 50 ms mean delay (10 ms packets). The calculation shows that the 100 ms objective of Y.1541 Class 0 can be met with a well-engineered access network (with a T1 or E1 rate or larger as Y.1541 requires) and with as many as 12 network routers. Appendix X/Y.1541 shows that similar speech quality can be maintained with reference terminals contributing a total delay of a less stringent 80 ms (using 20 ms packets and robust packet loss concealment). + +For *inter-regional* routes covered terrestrially, even those traversing the 27 500 km of the ITU's traditional worst-case Hypothetical Reference Connection, a VoIP mouth-to-ear path is likely to see a delay of just over 300 ms. This assumes terminals contributing a total of 80 ms delay (20 ms packets), a well-engineered access network and supporting IP network paths encountering 20 or fewer network routers (as per Appendix III/Y.1541). Of course, it is extremely unlikely that the worst case of 27 500 km will be encountered by many calls. For the much more frequent inter-regional calls of, for example, 10 000 km or less, the corresponding delays would be approximately 225 ms; certainly not as low (or as desirable) as 150 ms, but still quite satisfactory for the vast majority of users. + +Whilst delays in the mid-200 ms range may not be a serious problem for long inter-regional calls, where users expect calls to be somewhat different from regional calls, it is critical that network planners do not allow local and regional calls to encounter such delays because user expectations are that such calls be completely delay-transparent. + +Whilst it is recognized that using VoIP technologies will increase the delays well above that of non-packetized TDM transmission, this analysis demonstrates that the widespread use of end-end VoIP need not cause problematic delays if appropriate care and planning is exercised. + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.115-199602-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.115-199602-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..730c753f99adf50d5183cd5a452bb02194f65d9a --- /dev/null +++ b/marked/G/T-REC-G.115-199602-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:e110da6cf26f9d6ab2e00624ddd94bd14a5c0aa2847d3d115181438a09fa944e +size 8256 diff --git a/marked/G/T-REC-G.115-199602-I_PDF-E/raw.md b/marked/G/T-REC-G.115-199602-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..dce8b2ac2d810d7f08e0d72bfc3b8bc777b29f32 --- /dev/null +++ b/marked/G/T-REC-G.115-199602-I_PDF-E/raw.md @@ -0,0 +1,111 @@ + + +![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with the letters ITU and a lightning bolt. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.115** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(02/96) + +**TRANSMISSION SYSTEMS AND MEDIA** + +**GENERAL CHARACTERISTICS OF INTERNATIONAL +TELEPHONE CONNECTIONS AND INTERNATIONAL +TELEPHONE CIRCUITS** + +--- + +**MEAN ACTIVE SPEECH LEVEL FOR +ANNOUNCEMENTS AND SPEECH +SYNTHESIS SYSTEMS** + +**ITU-T Recommendation G.115** + +(Previously "CCITT Recommendation") + +--- + +# FOREWORD + +The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). + +ITU-T Recommendation G.115 was prepared by ITU-T Study Group 12 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 6th of February 1996. + +--- + +# NOTE + +In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# CONTENTS + +| | Page | +|---------------------------|-------------| +| 1 Introduction ..... | 1 | +| 2 Recommended level ..... | 1 | +| 3 Measuring method..... | 1 | +| 4 Reference point ..... | 2 | +| References ..... | 2 | + +# **SUMMARY** + +This Recommendation contains a recommendation for the mean active speech level to be used for setting the levels of announcement machines and speech synthesis systems in the telephone network. A level of $-19$ dBm0 is recommended, which presumes that the SLR of the telephones in the network is 8 dB, the long-term target value (referred to a 0 dBr point). If the present SLR in a national network is different, the recommended level can be adjusted, using a formula supplied, to a level consistent with that of live speech in the network. The recommended level is defined at the 0 dBr point, and to measure the level a speech voltmeter conforming to the requirements of Method B speech level meters in Recommendation P.56 should be used. + +# MEAN ACTIVE SPEECH LEVEL FOR ANNOUNCEMENTS AND SPEECH SYNTHESIS SYSTEMS + +(Geneva, 1996) + +# 1 Introduction + +With the deployment of automatic announcement systems and of speech synthesis systems in the telephone network, it is necessary to specify the proper level of the generated speech. The actual speech levels of live speech in the network depend on the send and receive efficiencies of the telephone sets. Recommendation P.310 specifies long-term objectives for the SLR and RLR of digital telephone sets. Different networks have different values of SLR and RLR in their telephones. Thus, the speech levels vary from one network to another. Information on actual speech levels in different networks and for different types of calls, e.g. national and international, is found in [1]. + +A recommendation on speech levels must take these differences into account. In this Recommendation, a recommended level based on the long-term SLR and RLR objectives is provided. As an option, a formula for adjusting the level to that of a particular network is also provided. + +## 2 Recommended level + +It is recommended that the mean active speech level generated in announcement machines in the telephone network be set to a nominal output level of $-19 \text{ dBm0}$ . + +This value presumes that the target value for SLR is 8 dB, referred to a 0 dBr point. Together with the target value for RLR of 2 dB, the recommended value of $-19 \text{ dBm0}$ will produce an average listening level at the subscriber's end that corresponds to the preferred listening level, as defined in Recommendation P.10. + +The recommended speech level also conforms with the existing levels in national networks, if the present SLR values are around 8 dB. If the national transmission plan for the present mixed analogue-digital network states a nominal $\text{SLR}_n$ (referred to a 0 dBr point) that differs significantly from 8 dB, an interim value for the level from announcement machines and synthesis systems which conforms better with the present levels in the network may be achieved by a correction for the difference. + +The correction, $C = 8 - \text{SLR}_n \text{ dB}$ , is added to the recommended value of $-19 \text{ dBm0}$ , in order to produce a higher or lower level, depending on the sign of the correction. By this correction, the interim level becomes: + +$L_i = -19 + C \text{ dBm0}$ , which is equivalent to: + +$L_i = -11 - \text{SLR}_n \text{ dBm0}$ . + +NOTE – For synthetic speech, it should be checked that the level balance between the individual words in an announcement, in particular for digits, is the same as for real speech. + +## 3 Measuring method + +The active speech level shall be measured in accordance with P.56 Method B. The necessary precision can be obtained for a duration of speech of at least 5 seconds. For longer announcements than 20 seconds, it is recommended that at least 20 seconds of active speech be measured. + +Instead of a speech signal, an artificial voice signal according to Recommendation P.50 may be used for setting the level. + +## 4 Reference point + +The reference point for the recommended speech level is 0 dBr as defined in Recommendation G.121. + +# References + +- [1] ITU-T COM 12-R 9-E (1994), *Report of WP 3/12 meeting* (Geneva, 23-24 February 1994), page 15, Table 1. +- [2] ITU-T COM 12-50-E (1995), *Basis for Recommendation G.115 on speech levels*, (Rapporteur Q.17/12). +- [3] ITU-T Recommendation P.310 (1996), *Transmission characteristics for telephone band (300-3400 Hz) digital telephones*. +- [4] ITU-T Recommendation P.10 (1993), *Vocabulary of terms on telephone transmission quality and telephone sets*. +- [5] ITU-T Recommendation P.56 (1993), *Objective measurement of active speech level*. +- [6] ITU-T Recommendation P.50 (1993), *Artificial voices*. +- [7] ITU-T Recommendation G.121 (1993), *Loudness Ratings (LRs) of national systems*. \ No newline at end of file diff --git a/marked/G/T-REC-G.120-199812-I_PDF-E/raw.md b/marked/G/T-REC-G.120-199812-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..adc3a48e3f800547061e55a25193335f98b0097a --- /dev/null +++ b/marked/G/T-REC-G.120-199812-I_PDF-E/raw.md @@ -0,0 +1,467 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.120** + +(12/98) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +International telephone connections and circuits – General +characteristics of national systems forming part of +international connections + +--- + +**Transmission characteristics of national +networks** + +ITU-T Recommendation G.120 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| General definitions | G.100–G.109 | +| General Recommendations on the transmission quality for an entire international telephone connection | G.110–G.119 | +| General characteristics of national systems forming part of international connections | G.120–G.129 | +| General characteristics of the 4-wire chain formed by the international circuits and national extension circuits | G.130–G.139 | +| General characteristics of the 4-wire chain of international circuits; international transit | G.140–G.149 | +| General characteristics of international telephone circuits and national extension circuits | G.150–G.159 | +| Apparatus associated with long-distance telephone circuits | G.160–G.169 | +| Transmission plan aspects of special circuits and connections using the international telephone connection network | G.170–G.179 | +| Protection and restoration of transmission systems | G.180–G.189 | +| Software tools for transmission systems | G.190–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +*For further details, please refer to ITU-T List of Recommendations.* + +# **TRANSMISSION CHARACTERISTICS OF NATIONAL NETWORKS** + +## **Summary** + +This Recommendation was revised to consolidate all the characteristics of national networks into one Recommendation. Additionally, it tightened the requirement for noise induced by power lines and it now makes provision for the addition of Asynchronous Transfer Mode (ATM) technology to be integrated into the PSTN. This Recommendation provides guidance regarding the performance of national networks. + +## **Source** + +ITU-T Recommendation G.120 was revised by ITU-T Study Group 12 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 3rd of December 1998. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | Page | +|--------------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References ..... | 1 | +| 3 Application of ITU-T Recommendations on telephone performance to national networks ..... | 2 | +| 4 National transmission plan ..... | 3 | +| 5 Attenuation distortion..... | 3 | +| 6 Circuit noise ..... | 5 | +| 6.1 Noise induced by power lines..... | 5 | +| 6.2 Noise contributed by transmission systems..... | 5 | +| 6.2.1 Analogue systems..... | 5 | +| 6.2.2 Use of companders to control noise on analogue systems..... | 6 | +| 6.2.3 Digital system..... | 6 | +| 6.2.4 Mixed circuits ..... | 6 | +| 6.3 Noise in a national 4-wire automatic exchange..... | 6 | +| 6.3.1 Analogue 4-wire automatic exchanges ..... | 6 | +| 6.3.2 Digital 4-wire automatic exchanges..... | 6 | +| 6.4 Noise allocation for a national system..... | 6 | +| 6.4.1 General planning assumptions ..... | 6 | +| 6.4.2 Noise allocations for planning digital systems..... | 7 | +| 6.4.3 Noise allocations for planning incremental analogue transport systems ..... | 7 | +| 7 Error on the reconstituted frequency ..... | 7 | +| 8 Group-delay distortion..... | 7 | +| 9 Linear crosstalk of circuits ..... | 8 | +| 10 Non-linear distortion of analogue transmission systems..... | 8 | +| 11 Variations of transmission loss with time ..... | 8 | +| Annex A – Noise allocation for a national system ..... | 8 | +| A.5 Large countries..... | 10 | + + + +## Recommendation G.120 + +# TRANSMISSION CHARACTERISTICS OF NATIONAL NETWORKS + +(revised in 1998) + +## 1 Scope + +This Recommendation provides transmission performance guidance for national networks that form part of international connections to provide international telephony services. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] *Transmission planning of switched telephone networks*, ITU, Geneva, 1976. +- [2] ITU-T Recommendation G.103 (1998), *Hypothetical reference connections*. +- [3] ITU-T Recommendation G.111 (1993), *Loudness Ratings (LRs) in an international connection*. +- [4] ITU-T Recommendation G.113 (1996), *Transmission impairments*. +- [5] ITU-T Recommendation G.114 (1996), *One-way transmission time*. +- [6] Recommendation G.1161, *Transmission performance objectives applicable to end-to-end international connections*. +- [7] ITU-T Recommendation G.121 (1993), *Loudness Ratings (LRs) of national systems*. +- [8] ITU-T Recommendation G.122 (1993), *Influence of national systems on stability and talker echo in international connections*. +- [9] ITU-T Recommendation G.131 (1996), *Control of talker echo*. +- [10] ITU-T Recommendation G.173 (1993), *Transmission planning aspects of the speech service in digital public land mobile networks*. +- [11] ITU-T Recommendation G.174 (1994), *Transmission performance objectives for terrestrial digital wireless systems using portable terminals to access the PSTN*. +- [12] ITU-T Recommendation G.175 (1997), *Transmission planning for private/public network interconnection of voice traffic*. +- [13] CCITT Recommendation G.232 (1984), *12-channel terminal equipments*. +- [14] Recommendation G.235 (1988, withdrawn, *Blue Book*, Volume III, Fascicle III.2.) – *16-channel terminal equipments*. + +--- + +1 Presently at the stage of draft. + +- [15] ITU-T Recommendation G.712 (1996), *Transmission performance characteristics of pulse code modulation channels.* +- [16] CCITT Recommendation Q.31 (1988), *Noise in a national 4-wire automatic exchange.* +- [17] CCITT Recommendation Q.45 (1984), *Transmission characteristics of an analogue international exchange.* +- [18] ITU-T Recommendation Q.551 (1996), *Transmission characteristics of digital exchanges.* +- [19] ITU-T Recommendation Q.552 (1996), *Transmission characteristics at 2-wire analogue interfaces of digital exchanges.* +- [20] ITU-T Recommendation Q.553 (1996), *Transmission characteristics at 4-wire analogue interfaces of digital exchanges.* +- [21] ITU-T Recommendation Q.554 (1996), *Transmission characteristics at digital interfaces of digital exchanges.* + +## 3 Application of ITU-T Recommendations on telephone performance to national networks + +The different parts of a national network provided by both analogue and digital transmission systems to be used for an international connection should meet the following general recommendations: + +### 3.1 The national sending and receiving systems should satisfy the limits recommended in: + +- Recommendation G.113 as regards to transmission impairments; +- Recommendation G.114 as regards to group delay; +- Recommendation G.121 as regards to Loudness Rating (LR); +- Recommendation G.122 as regards to balance return loss and transmission loss; +- Recommendation G.131 as regards to echo control2; +- Recommendation G.120: + - Clause 5 as regards to attenuation distortion; + - Clause 6 as regards to circuit noise; + - Clause 7 as regards to error on the reconstituted frequency; + - Clause 8 as regards to group delay distortion; + - Clause 9 as regards to linear crosstalk of circuits3; + - Clause 10 as regards to non-linear distortion of analogue transmission systems; and + - Clause 11 as regards to variations of transmission loss with time. + +### 3.2 Long-distance trunk circuits forming part of the main arteries of the national network should be high-velocity propagation circuits which enable the limits fixed in Recommendation G.114 to be respected. + +--- + +2 Recommendation G.131 applies to control of network originated echo. Additional guidance for echo control can be found in: Recommendation G.116 for terminals, Recommendation G.173 for connecting digital public land mobile networks, Recommendation G.174 for connecting terrestrial digital wireless systems using portable terminals and Recommendation G.175 for connecting private networks. + +3 Guidance applicable to linear crosstalk on connections can be found in Recommendation G.116. + +**3.3** National trunk circuits should have characteristics enabling them to conform to Recommendation G.131. + +**3.4** International centres [Plesiochronous Digital Hierarchy (PDH)/Synchronous Digital Hierarchy (SDH)] should satisfy Recommendations Q.551, Q.552, Q.553 and Q.554. + +National automatic analogue 4-wire centres should observe the noise limits specified in Recommendation Q.31.4 + +National digital switching centres should satisfy Recommendations Q.551, Q.552, Q.553 and Q.554. + +International and national switching centres (Asynchronous Transfer Mode) should, in general, meet the Q.500-series Recommendations.5 + +## **4 National transmission plan** + +Every Administration is free to choose whatever method it considers appropriate for specifying transmission performance and to adopt the appropriate limits to ensure satisfactory quality for national calls. Nevertheless, the recommendations relating to Loudness Ratings (LRs), Recommendation G.121, should be satisfied for international calls. + +NOTE – To meet this twofold condition with respect to national and international calls, each Administration has to draw up a national transmission plan, i.e. it must specify limits for each part of the national network. + +The manual cited in [1] contains descriptions of the transmission plans adopted by various countries and also some indications concerning the methods that can be used to establish such a plan. + +In particular, Annexes A and B to Recommendation G.111 contain useful information for Administrations who wish to apply the LR method to their national connections. + +## **5 Attenuation distortion** + +The circuit performance objectives for attenuation distortion of international circuits and national extension circuits were originally selected so that acceptable performance would be obtained on analogue 4-wire chains of up to 12 circuits. Although it is recognized that the network is continuing its evolution to an all digital network, it is recommended that the individual equipment network performance objectives as presented in the following Recommendations not be relaxed: G.232 (which gives equipment design objectives for analogue 12-channel terminal equipments); G.712 (which gives equipment design objectives for digital PCM channelizing equipments); and Q.552 and Q.553 (which give equipment design objectives for digital switches). + +It follows from the Recommendations mentioned above that, as a rule, the frequency band effectively transmitted by a telephone circuit, according to the definition adopted by the ITU-T (i.e. the band in which the attenuation distortion does not exceed 9 dB compared with the value for 1020 Hz), will be a little wider than the 300-3400 Hz band, and for a single pair of channel terminal equipments of this type, the attenuation distortion at 300 Hz and 3400 Hz should never exceed 3 dB and in a large number of equipments should not average more than 1.7 dB. It is recommended that all channel terminal equipments, including digital switches with analogue interfaces, be designed such that they can comply with the line-up limits specified in Figure 1. Analogue terminal equipments with + +--- + +4 In accordance with Recommendation Q.31, the limits are the same as those which were specified in Recommendation Q.45 of the *Red Book* (1984). + +5 For example, the group delay requirement cannot be met if cell assembly of DS-0 rates is performed. + +3-kHz-channel spacing, i.e. equipment intended to be G.235 compliant (Note that Recommendation G.235 is no longer in force.) is no longer recommended for use in international connections. + +![Figure 1/G.120 – Line-up limits of circuits with 4-kHz channel equipment. The graph shows Attenuation (dB) on the y-axis (from -1.0 to 10) versus Frequency (Hz) on the x-axis (from 200 to 3400). The curve is a step function representing the line-up limits. It starts at 0 dB from 200 Hz to 300 Hz, drops to -0.5 dB at 300 Hz, then to -1.0 dB at 400 Hz. It remains at -1.0 dB until 2400 Hz, where it steps up to 1.0 dB. At 3000 Hz, it steps up to 2.0 dB. At 3050 Hz, it steps up to 3.5 dB. At 3400 Hz, it steps up to 10 dB. The legend indicates this is for circuits with equipments having 4-kHz spacing, based on Recommendation G.232 [13].](4e0ade2f41b66d5602160da5cc978274_img.jpg) + +| Frequency (Hz) | Attenuation (dB) | +|----------------|------------------| +| 200 - 300 | 0 | +| 300 - 400 | -0.5 | +| 400 - 2400 | -1.0 | +| 2400 - 3000 | 1.0 | +| 3000 - 3050 | 2.0 | +| 3050 - 3400 | 3.5 | +| 3400 - 3400 | 10 | + +Figure 1/G.120 – Line-up limits of circuits with 4-kHz channel equipment. The graph shows Attenuation (dB) on the y-axis (from -1.0 to 10) versus Frequency (Hz) on the x-axis (from 200 to 3400). The curve is a step function representing the line-up limits. It starts at 0 dB from 200 Hz to 300 Hz, drops to -0.5 dB at 300 Hz, then to -1.0 dB at 400 Hz. It remains at -1.0 dB until 2400 Hz, where it steps up to 1.0 dB. At 3000 Hz, it steps up to 2.0 dB. At 3050 Hz, it steps up to 3.5 dB. At 3400 Hz, it steps up to 10 dB. The legend indicates this is for circuits with equipments having 4-kHz spacing, based on Recommendation G.232 [13]. + +**Figure 1/G.120 – Line-up limits of circuits with 4-kHz channel equipment** + +NOTE 1 – The ITU-T examined the possibility of recommending a specific frequency below 300 Hz as the lower limit of the frequency band effectively transmitted by network channelizing equipments, taking the following considerations into account: + +- 1) The results of subjective tests carried out by certain Administrations show that it is possible to improve transmission quality if the lower limit of the transmitted frequency band is reduced from 300 Hz to 200 Hz. These tests show a definite increase in the loudness of the received speech, and also in the quality of the transmission as judged by opinion tests; the improvement in articulation is, on the other hand, very slight. +- 2) However, such an extension would probably have the following disadvantages: + - a) it would slightly increase the cost of equipment; + - b) it would introduce some difficulties in balancing the terminating sets at the ends of the 4-wire chain, if it were desired to use 4-wire circuits without exceeding the values of nominal transmission loss recommended in the new transmission plan; + - c) it would increase the possible susceptibility to interference, whether as subjective noise or as disturbances interfering with carrier equipment; + +- d) the additional energy transmitted in consequence of extending the band could increase the loading of carrier systems; +- e) the out-of-band signalling systems recognized by the ITU-T could not be used. + +In view of the above, the ITU-T has issued the aforementioned Recommendations (G.232, G.712, Q.552 and Q.553) concerning signals transmitted at frequencies between 300 and 3400 Hz on network channelizing equipments. + +NOTE 2 – In applying the Recommendations (G.232, G.712, Q.552 and Q.553), Administrations may mutually agree to transmit signals at frequencies below 300 Hz over international circuits. Every Administration may, of course, decide to transmit signals at frequencies below 300 Hz over its national extension circuits, provided it is still able to apply the ITU-T transmission plan to international communications. + +## **6 Circuit noise** + +### **6.1 Noise induced by power lines** + +The network performance objective for the noise produced from the influence of all the power lines affecting one or more parts of a chain of telephone lines6 joining a subscriber's set to its international centre should not exceed 0.5 mV (psophometric weighed), this being the value at the line6 terminals of the subscriber's set (when receiving), it being assumed that the telecommunication installations inserted in that chain are balanced to earth as perfectly as possible, in conformity with the most modern equipment construction. + +It should be noted that, even in the case of perfectly balanced lines6, the insertion of equipment having too great a degree of unbalance to earth may cause unacceptable noise at the customer's terminal. + +In every national network, it is usually possible, in practice, to find switching centres such that some of the lines6 that terminate at those centres (lines6 in cable, conforming to ITU-T Recommendations) are free from noise arising from neighbouring power lines. It is then sufficient to determine the psophometric e.m.f.s arising from all the power lines6 affecting one or more parts of the chain of lines6 joining such a centre to the subscriber's set. + +### **6.2 Noise contributed by transmission systems** + +#### **6.2.1 Analogue systems** + +##### **6.2.1.1 Analogue circuit ranging in length from very short distances up to 2500 km** + +The circuits in question are mostly set up in cable or radio-relay link carrier systems, such that the noise objectives of Recommendation G.222 are applicable to a circuit with the same make-up as the hypothetical reference circuit 2500 km long. + +A consequence of Recommendation G.222 is that for a circuit the accumulated line noise should correspond to an average of not more than 2 pW0p/km, excluding very short circuits and those with a very complicated composition. Subclause 6.4 provides planning information regarding noise allocation for incremental analogue systems. + +NOTE 1 – The permissible noise contributions from equipment do not depend on whether the circuits form part of the international 4-wire chain or are connected to it by 2-wire switching. However, the circuit noise powers assume that the hypothetical reference connections of Recommendation G.103 are, or will be in + +--- + +6 "Line" as used in 6.1 should be understood as meaning subscriber's line, trunk junction or trunk circuit. + +future, reasonably typical of connections. They also assume that the total length of circuits connecting the local exchange to the primary centre is not excessive. + +NOTE 2 – Under the above conditions and assuming the maximum noise values permitted for pairs of channel modulators (200 pW0p), group modulators (80 pW0p) and supergroup modulators (60 pW0p), a total noise power of 500 pW0p will not be exceeded by a circuit connecting the local exchange to the primary centre (Figure 6/G.103) when its length is less than about 50 to 100 km. + +##### **6.2.1.2 Very long-distance circuits (about 2500-25 000 km)** + +The circuits in question are mostly set up in cable or radio-relay link carrier systems, such that the noise objectives of Recommendation G.222 are applicable. + +A consequence of Recommendation G.222 is that for these circuits the accumulated line noise should correspond to an average of not more than 2 pW0p/km. Subclause 6.4 provides planning information regarding noise allocation for incremental analogue systems. + +#### **6.2.2 Use of companders to control noise on analogue systems** + +Companders are no longer recommended for use on international connections. + +#### **6.2.3 Digital system** + +Circuits provided by PCM systems which accord with Recommendation G.712 will have an acceptable noise performance which is substantially independent of their length. + +#### **6.2.4 Mixed circuits** + +The noise value in a circuit provided by both analogue and digital transmission systems depends on the whole length of analogue sections and of the number of codecs in a circuit. The noise generated in the analogue segment of the circuit should not be inconsistent with the noise recommendations of 6.2.1 above. + +### **6.3 Noise in a national 4-wire automatic exchange7** + +#### **6.3.1 Analogue 4-wire automatic exchanges** + +The noise requirements for an analogue 4-wire automatic exchange are specified in Recommendation Q.31 which contained limits similar to those which were specified in Recommendation Q.45. + +The ITU-T recommends that no more than analogue 4-wire automatic exchanges be implemented to meet international traffic communications needs. + +#### **6.3.2 Digital 4-wire automatic exchanges** + +The digital switch should comply with Recommendations Q.551, Q.552, Q.553 and Q.554. + +### **6.4 Noise allocation for a national system** + +#### **6.4.1 General planning assumptions** + +Network planning should recognize the current state of evolution of the network and the rapid growth of digital wireless access services. As a result, operating configurations using analogue accesses and digital circuits, i.e. IDNs configured as per Figures 2/G.103 and 3/G.103, or digital accesses and telephone sets, i.e. ISDNs configured as per Figure 1/G.103, should be considered the norm in the majority of the national systems. + +--- + +7 In accordance with Recommendation Q.31 [16], the limits are the same as in Recommendation Q.45 [17]. + +#### **6.4.2 Noise allocations for planning digital systems** + +Noise allocation on a national basis is not required when national systems are planned using operating configurations consistent with Figures 1/G.103, 2/G.103 and 3/G.103. + +#### **6.4.3 Noise allocations for planning incremental analogue transport systems** + +Noise allocation, when planning to increment a national access arrangement using analogue technology, should comply with the following. + +The noise powers indicated in the following text are nominal values. + +Network planning should be such that the noise power entering the international network and attributable to national sending systems meets the limits of the following rule: + +The psophometric noise power introduced by the national sending system at a point of zero relative level on the first international circuit must not exceed either $(4000 + 4L)$ or $(7000 + 2L)$ pWp, whichever is less, and where $L$ is the total length in kilometres of the long-distance FDM carrier systems in the national chain. The corresponding quantities referred to the send virtual switching point are $(1800 + 1.8L)$ and $(3100 + 0.9L)$ pWp. + +The derivation of this rule is explained in Annex A. + +NOTE – A problem, which has already arisen in some national networks, as regards the receiving direction, is that when losses are reduced the circuit noise becomes more noticeable, particularly during periods of no conversation. This is particularly relevant in the case of large countries in which the noise contribution from line systems is high. Hence, if an Administration complies with a recommendation concerning national noise power levels and then subsequently improves transmission, perhaps by introducing 4-wire switching in lower-order exchanges, it may find itself in a worse situation as regards noise. It follows that it is important to preserve a proper balance between noise and loss. + +## **7 Error on the reconstituted frequency** + +The recommended method of implementing active echo control to operate in compliance with Recommendation G.131 is through the use of echo cancellers. However, echo cancellers require that there be constraints placed on the error on the reconstituted frequency within the echo path. As the channels of any international telephone circuit should be suitable for terminating any international call, the network performance objective for the accuracy of the virtual carrier frequencies should be such that the difference between an audio frequency applied to one end of the circuit and the frequency received at the other end should not exceed 2 Hz, even when there are intermediate modulating and demodulating processes. + +## **8 Group-delay distortion** + +The network performance objectives for the permissible differences for a national 4-wire extension, between the minimum group delay (throughout the transmitted frequency band) and the group delay at the lower and upper limits of this frequency band are indicated in the Table 1. + +Group-delay distortion is of importance over a band of frequencies where the attenuation is of importance, i.e. at which the attenuation is less than 10 dB relative to the value at 800 Hz. This will normally be the case for frequencies higher than about 260-320 Hz and lower than about 3150-3400 Hz respectively for the lower and upper limit of the frequency band as indicated in Table 1. + +**Table 1/G.120 – Group-delay distortion limits for national 4-wire extensions** + +| | Lower limit of frequency band (ms) | Upper limit of frequency band (ms) | +|--------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------|-------------------------------------------| +| Each of the national 4-wire extensions. | 15 | 7.5 | +| NOTE – Limits given in Table 1 should be met both for analogue circuits and mixed circuits with analogue and digital sections. | | | + +## **9 Linear crosstalk of circuits** + +The circuit performance objective for the near-end or far-end crosstalk ratio (intelligible crosstalk only) measured at audio-frequency at trunk exchanges between two complete circuits in terminal service position should not be less than 65 dB. + +NOTE – When a minimum noise level of at least 4000 pW0p is always present in a system (e.g. this may be the case in analogue satellite systems), a reduced crosstalk ratio of 58 dB between circuits is acceptable. + +## **10 Non-linear distortion of analogue transmission systems** + +Experience has shown that telephone circuits set up on systems for which the ITU-T has issued Recommendations (the elements of which systems, taken separately, meet the relevant non-linearity requirements) are suitable for telephone transmission. + +NOTE – In analogue carrier telephone circuits, the non-linear distortion produced by the line amplifiers and by modulation stages other than the channel-translating equipment can be ignored. Hence the above remarks are applicable to circuits of any length. + +## **11 Variations of transmission loss with time** + +The ITU-T recommends the following objectives: + +- The standard deviation of the variation in transmission loss of a circuit should not exceed 1 dB. This objective can be obtained already for circuits on a single group link equipped with automatic regulation and should be obtained for each national circuit, whether regulated or not. +- The difference between the mean value and the nominal value of the transmission loss for each circuit should not exceed 0.5 dB. + +## **ANNEX A** + +### **Noise allocation for a national system** + +**A.1** It is desirable that the noise power arising in national networks be limited in terms of the level appearing at the virtual switching points – the agreed interface between the national and the international network. In order to do this, some particular distribution of losses within the national network must be assumed. The solution is to adopt an agreed reference connection in order to specify maximum noise power levels from national sources referred to the virtual switching point of the international circuit. + +**A.2** Having regard to the way in which national networks are constructed, it is appropriate to express the noise allowance in the form $A + BL$ where $A$ is a fixed allowance resulting from noise in exchanges and from short-haul multiplex systems, $B$ is an allowance for a noise rate per unit length from long-haul multiplex systems and $L$ is the total length of these latter systems in the national portion of the international connection. Two such expressions are necessary, one for countries of average size and another for large countries (in the sense of Recommendation G.121). + +**A.3** This approach is comparatively straightforward in the national sending system and serves to limit the amount of noise injected into the international connection. + +**A.4** *Average-sized countries* [i.e. not greater than 1500 km from the International Switching Centre (ISC) to the most remote local exchange]. + +The relevant hypothetical reference chain for the national sending system is given in Figure A.1. The circuit between the local exchange and the primary centre is assumed to be routed on an FDM carrier system of length not exceeding 250 km and operated at a nominal loss of 3 dB. The noise power on this circuit is taken to be the maximum value of 2000 pW0. The circuit between the primary centre and the secondary centre is also assumed to be routed on an FDM carrier system of the same type. + +The line noise power rate of the two long-distance trunk circuits is assumed to be 4 pW/km and the total line length of these two circuits ( $L_1 + L_2$ in Figure A.1) approaches the limit of 1500 km arbitrarily defining "a country of average size" in Recommendation G.121. It is thus assumed that the distance covered by the two short-haul systems is a very small proportion of the total length of the complete national sending system. + +Each exchange is assumed to contribute 200 pWp in accordance with Recommendation G.103, Note 11 to Figure 6/G.103 and Recommendation Q.31. + +![Diagram of a hypothetical reference chain for the national sending system. It shows a sequence of nodes: Local exchange (Analogue), Primary centre (Analogue), Secondary centre (Analogue), Tertiary centre (Analogue), and ISC (Digital). The total distance from the Local exchange to the ISC is labeled as <1500 km. The distance from the Primary centre to the ISC is labeled as L. The distance from the Secondary centre to the ISC is labeled as L1. The distance from the Tertiary centre to the ISC is labeled as L2. The distance from the Local exchange to the Primary centre is labeled as 3 dB. The distance from the Primary centre to the Secondary centre is labeled as 0 dB. The distance from the Secondary centre to the Tertiary centre is labeled as 0 dB. The distance from the Tertiary centre to the ISC is labeled as 0 dB. The noise power at the Local exchange is 200 pW0p. The noise power at the Primary centre is 200 pW0p. The noise power at the Secondary centre is 200 pW0p. The noise power at the Tertiary centre is 200 pW0p. The noise power at the ISC is 0 pW0p. The noise power at the Local exchange is also labeled as 2000 pW0p. The noise power at the Primary centre is also labeled as 2000 pW0p. The noise power at the Secondary centre is also labeled as ≤ L1 pW0p. The noise power at the Tertiary centre is also labeled as ≤ L2 pW0p. The diagram is labeled T1208940-98.](9ae17964ddd9b814c7d905b1af2fddf2_img.jpg) + +Diagram of a hypothetical reference chain for the national sending system. It shows a sequence of nodes: Local exchange (Analogue), Primary centre (Analogue), Secondary centre (Analogue), Tertiary centre (Analogue), and ISC (Digital). The total distance from the Local exchange to the ISC is labeled as <1500 km. The distance from the Primary centre to the ISC is labeled as L. The distance from the Secondary centre to the ISC is labeled as L1. The distance from the Tertiary centre to the ISC is labeled as L2. The distance from the Local exchange to the Primary centre is labeled as 3 dB. The distance from the Primary centre to the Secondary centre is labeled as 0 dB. The distance from the Secondary centre to the Tertiary centre is labeled as 0 dB. The distance from the Tertiary centre to the ISC is labeled as 0 dB. The noise power at the Local exchange is 200 pW0p. The noise power at the Primary centre is 200 pW0p. The noise power at the Secondary centre is 200 pW0p. The noise power at the Tertiary centre is 200 pW0p. The noise power at the ISC is 0 pW0p. The noise power at the Local exchange is also labeled as 2000 pW0p. The noise power at the Primary centre is also labeled as 2000 pW0p. The noise power at the Secondary centre is also labeled as ≤ L1 pW0p. The noise power at the Tertiary centre is also labeled as ≤ L2 pW0p. The diagram is labeled T1208940-98. + +NOTE – The noise values shown in this figure are maximum values; see also the corresponding element of Figure 1/G.103. + +**Figure A.1/G.120** + +The total noise power level referred to a point of zero relative level on the first international circuit at the ISC is (moving from right to left and adding in each successive noise contribution encountered): + +$$0 + 4L_2 + 200 + 4L_1 + 200 + 2000 + 200 + \frac{1}{2}(2000) + \frac{1}{2}(200) = 3900 + 4L \text{ pW0}$$ + +where $L = L_1 + L_2$ . This may be conveniently rounded off to $4000 + 4L \text{ pW0}$ . + +This expression is valid for $L$ not exceeding 1500 km leading to, at that distance, 10 000 pW0. + +### A.5 Large countries + +When $L$ is in excess of 1500 km the additional long-distance circuits in the national network should in principle be engineered to international standards, and in particular some large countries have found it necessary to plan national systems with noise power rates lower than 4 pW/km. + +A convenient value to assume is 2 pW/km; this is in rough agreement with the practice of one such large country and is also in line with Recommendation G.153. + +The rule for large countries has been established as shown in Figure A.2 in which the $4000 + 4L$ rule is shown passing through the point (1500 km, 10 000 pW). A line with a slope of 2 pW/km is constructed to pass through the same point and its intercept is seen to be 7000 pW. Hence the rule for large countries is $7000 + 2L \text{ pW0}$ . (The 0.5 dB nominal loss of the last national circuit has been ignored for simplicity's sake.) + +![Figure A.2/G.120: A graph showing the sending noise power limit (pW0p) versus the total length of national long-distance FDM carrier system (km). The y-axis ranges from 0 to 20,000 pW0p in increments of 2,000. The x-axis ranges from 0 to 3,500 km in increments of 500. A solid line represents the 4000 + 4L rule, starting at 4,000 pW0p at 0 km and increasing with a slope of 4 pW/km until it reaches 10,000 pW0p at 1,500 km. From 1,500 km to 3,500 km, a dashed line represents the 7000 + 2L rule, starting at 10,000 pW0p and increasing with a slope of 2 pW/km. A shaded gray region is shown between the two lines from 0 to 1,500 km. Arrows indicate the slopes of 4 pW/km and 2 pW/km. The text 'T1208950-98' is in the bottom right corner.](0bd23f00e0632855cfef9274f1ab93d8_img.jpg) + +Figure A.2/G.120: A graph showing the sending noise power limit (pW0p) versus the total length of national long-distance FDM carrier system (km). The y-axis ranges from 0 to 20,000 pW0p in increments of 2,000. The x-axis ranges from 0 to 3,500 km in increments of 500. A solid line represents the 4000 + 4L rule, starting at 4,000 pW0p at 0 km and increasing with a slope of 4 pW/km until it reaches 10,000 pW0p at 1,500 km. From 1,500 km to 3,500 km, a dashed line represents the 7000 + 2L rule, starting at 10,000 pW0p and increasing with a slope of 2 pW/km. A shaded gray region is shown between the two lines from 0 to 1,500 km. Arrows indicate the slopes of 4 pW/km and 2 pW/km. The text 'T1208950-98' is in the bottom right corner. + +Figure A.2/G.120 + +## ITU-T RECOMMENDATIONS SERIES + +- Series A Organization of the work of the ITU-T +- Series B Means of expression: definitions, symbols, classification +- Series C General telecommunication statistics +- Series D General tariff principles +- Series E Overall network operation, telephone service, service operation and human factors +- Series F Non-telephone telecommunication services +- Series G Transmission systems and media, digital systems and networks** +- Series H Audiovisual and multimedia systems +- Series I Integrated services digital network +- Series J Transmission of television, sound programme and other multimedia signals +- Series K Protection against interference +- Series L Construction, installation and protection of cables and other elements of outside plant +- Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits +- Series N Maintenance: international sound programme and television transmission circuits +- Series O Specifications of measuring equipment +- Series P Telephone transmission quality, telephone installations, local line networks +- Series Q Switching and signalling +- Series R Telegraph transmission +- Series S Telegraph services terminal equipment +- Series T Terminals for telematic services +- Series U Telegraph switching +- Series V Data communication over the telephone network +- Series X Data networks and open system communications +- Series Y Global information infrastructure +- Series Z Programming languages \ No newline at end of file diff --git a/marked/G/T-REC-G.126-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.126-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..1c7c8ff27b9fff7480ea06921d044959dd607324 --- /dev/null +++ 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0000000000000000000000000000000000000000..283e2f0285ea1788e997f6979c4fc2db6538001f --- /dev/null +++ b/marked/G/T-REC-G.192-199603-I_PDF-E/raw.md @@ -0,0 +1,596 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.192** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(03/96) + +**GENERAL CHARACTERISTICS OF INTERNATIONAL +TELEPHONE CONNECTIONS AND INTERNATIONAL +TELEPHONE CIRCUITS** + +--- + +**A COMMON DIGITAL PARALLEL INTERFACE +FOR SPEECH STANDARDISATION ACTIVITIES** + +**ITU-T Recommendation G.192** + +(Previously "CCITT Recommendation") + +--- + +# FOREWORD + +The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). + +ITU-T Recommendation G.192 was prepared by ITU-T Study Group 15 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of March 1996. + +--- + +# NOTE + +In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# CONTENTS + +| | Page | +|----------------------------------------------------------------------------|-------------| +| 1 Scope..... | 1 | +| 2 Introduction ..... | 1 | +| 3 Definitions..... | 1 | +| 4 General Description of the Digital Parallel Interface ..... | 2 | +| 4.1 Logical Description ..... | 3 | +| 4.2 Master Clock and Reset..... | 3 | +| 4.3 Timing, Timeslots and Capacity ..... | 4 | +| 4.4 Reset procedure ..... | 5 | +| 5 Hardware implementation ..... | 5 | +| 5.1 Connector type, pin assignment and cabling ..... | 5 | +| 5.2 Line drivers and receiver termination ..... | 5 | +| 5.3 Distributed multiplexer..... | 5 | +| 5.4 Signal delays within devices..... | 9 | +| Annex A – DPI implementation using TTL logic integrated circuits..... | 9 | +| Annex B – Data formats ..... | 12 | +| B.1 Time signals..... | 13 | +| B.2 Coded bitstream ..... | 14 | +| Annex C – Rules for codec implementation..... | 15 | +| Annex D – Example host laboratory test configurations..... | 15 | +| Appendix I – The ITU-T 8 kbit/s speech codec test parallel interface ..... | 17 | +| I.1 Specialisation of the interface..... | 17 | +| I.2 Data formats..... | 18 | +| References ..... | 18 | + +# **ABSTRACT** + +This Recommendation defines the physical, electrical and logical specification of a digital parallel interface which is to be used to interconnect the different devices needed in standardisation activities of speech codecs sponsored by the ITU-T. + +Included in this Recommendation are the data formats at the input and output of the encoder, decoder and bit manipulation devices. + +Finally, rules for the implementation of codecs to guarantee proper interoperation of devices interconnected using that digital parallel interface are presented. + +# A COMMON DIGITAL PARALLEL INTERFACE FOR SPEECH STANDARDISATION ACTIVITIES + +(Geneva, 1996) + +# 1 Scope + +This Recommendation describes a 16-bit parallel input and output interface for the interconnection of test and reference devices in ITU-T standardisation activities. + +# 2 Introduction + +The history of the Digital Parallel Interface (DPI) specification goes back to the CCITT wideband speech 64 kbit/s codec tests that led to the present Recommendation G.722, where a similar parallel interface was used. That interface was simplified to fit into a 25-pin connector for the host laboratory sessions of the subjective tests of the GSM full rate codec. This simplified interface has also been used in the standardisation of the second generation GSM system and in the standardisation of the ITU-T 8 kbit/s speech coder. The interface is simple to build and easy to use and, compared to a serial interface, allows for a simpler access to the data flow for monitoring and measuring codec parameters, e.g. delay and timing. + +This Recommendation is structured as follows: initially an overview of the principles of the interface is given, with a functional description of the signals and data lines. Then hardware aspects are considered. Specialisations of the interface are given in the annexes. These specialisations involve: + +- the DPI implementation using TTL family integrated circuits; +- description of data formats based on the type of device where the DPI is employed; +- device implementation rules when the device is a speech coder; and +- configuration examples for the DPI. + +For information, a description of the specialisation used for the host laboratory work of the ITU-T 8 kbit/s coder is given as an appendix. + +# 3 Definitions + +For the purposes of this Recommendation, the following definitions and abbreviations apply. + +3.1 **codec**: An encoder/decoder pair. + +3.2 **coded bitstream signal**: One of the possible signal representations on the DPI, in general representing the signal at the output of an encoder, or the input of a decoder. May also be the representation of a communication channel. + +3.3 **CuT**: Codec under Test. + +3.4 **DPD**: Digital Processing Device. + +3.5 **DPI**: The Digital Parallel Interface defined in this Recommendation. + +3.6 **interface timeslot (INTI)**: A rising-edge to rising-edge time interval of the clock signal. A marked INTI refers to a INTI that occurs together with the Mark signal active (high) and an unmarked INTI when Mark is low. + +3.7 **LSb**: Least Significant bit. + +3.8 **mark signal (mark)**: A one-bit signal that indicates whether the data on the data bus is valid or not. + +3.9 **MSb**: Most Significant bit. + +**3.10 normal operation:** Mode of operation of the interface used for regular processing by the devices. Alternative to the reset operation. + +**3.11 reset operation:** A procedure started when the Reset signal is active for 16 INTIs, and that lasts 1616 INTIs in total. Used to synchronise all the devices in the chain to their initial reset state. After the end of the Reset Operation, the DPI and the interconnected devices resume Normal Operation. + +NOTE – 1616 INTIs represent 1 ms (16 INTIs) plus 100 ms (1600 INTIs) for a 16 kHz clock. + +**3.12 reset:** Active-low, one bit signal used to start the Reset Operation. + +**3.13 Rx\_Clk:** Backwards clock signal. Used to clock devices when the clock master lies in one of the intermediate devices of the chain. + +**3.14 softbit:** An element of the coded bitstream signal where logical bits '1' and '0' are represented by 16-bit right adjusted words. + +**3.15 synchronisation word:** An element of the coded bitstream signal provided for synchronisation and frame erasure purposes. + +**3.16 time signal:** Another of the possible signal representations on the DPI, in general representing time samples. Used necessarily between data source, data sink, and codecs. + +**3.17 Tx\_Clk:** Forward clock signal. A continuous-time running signal providing the basic rate of the interconnected devices. + +# 4 General Description of the Digital Parallel Interface + +Normally, a set of digital test data is processed over different Codecs under Test (CuT) during a standardisation procedure of a speech codec by the ITU-T. Figure 1 shows an example of test configuration where three Digital Processing Devices (DPD) are interconnected by means of the DPI. Each of the DPD have an input and an output DPI. + +![Diagram of a generic test configuration showing a Data Source connected to three Digital Processing Devices (DPD) in series, which are then connected to a Data Sink. Each connection point is labeled DPI.](43fec6623ab9cb223a9ff74e2d2a4402_img.jpg) + +The diagram illustrates a linear chain of components. On the far left is a 'Data Source' represented by a cylinder icon. A line connects it to a rectangular box labeled 'Digital Processing Device 1'. This connection is marked with a small black circle and the label 'DPI'. From 'Digital Processing Device 1', another line with a 'DPI' marker connects to a second rectangular box labeled 'Digital Processing Device 2'. From 'Digital Processing Device 2', a third line with a 'DPI' marker connects to a third rectangular box labeled 'Digital Processing Device 3'. Finally, a line with a 'DPI' marker connects 'Digital Processing Device 3' to a 'Data Sink' represented by a cylinder icon on the far right. + +Diagram of a generic test configuration showing a Data Source connected to three Digital Processing Devices (DPD) in series, which are then connected to a Data Sink. Each connection point is labeled DPI. + +T1519660-95/d01 + +FIGURE 1/G.192 + +## A generic test configuration where the DPI is used + +A set of digital test data (usually digitised speech) is sent out synchronously from the data source to the first DPD, what could be the encoding portion of a CuT. Processed data is then sent in an appropriate format to the second DPD in the chain, for example a channel model. After processing by the second DPD, data is sent to the final DPD in the example chain, what could be the decoding portion of a CuT. Data out of this last DPD is finally collected by the data sink. It should be noted that the data type in the different usages of the DPI in Figure 1 does not need to have the same format. + +Any number of DPD could be connected in principle, allowing to build complex structures (e.g. to simulate a tandem of codecs in two different digital cellular mobile systems). Other application examples are given in Annex D. + +The interface is able to transport in parallel up to 16 bits of Data (D15..D0) from one device (transmitter) to another (receiver). Valid data words are identified by mark bits. + +A clock signal is transmitted in parallel with the data lines of the interface in the forward direction (Tx\_Clk). A clock signal is also available in the backward direction (Rx\_Clk), what can be used for special purposes. An active-low /Reset signal is applied for synchronisation of the devices in a chain. + +## 4.1 Logical Description + +Test hardware configurations may differ in each standardisation process. However, the basic format for the data passing through the DPI is the same. It is composed of 16-bit data words, clocked in and out at a certain rate (e.g. 16 kHz) and marked as valid or invalid by a special mark bit, as indicated in Figure 2. The transmission throughout the test configuration is processed synchronously and the mark bit identifies whether the preceding device was ready to send out data or not. + +Figure 3 describes a generic hardware structure for the DPI. All data, mark and clock lines are buffered in both transmitter and receiver ends. The data and mark bits are stored in a parallel register during one interface timeslot. The hardware structure is independent of the logic family used, but the same family is needed for a given pair transmitter and receiver interconnected ends. If a termination is needed to reduce signal reflections, it needs to be adequate (and possibly specific) to the logic family chosen. + +![Timing diagram showing 16-bit data flow (D15-D0) and a Mark bit over time. The diagram uses 'i', 'n', 'v', 'a', 'l', 'd' for invalid and 't', 'a', 'd' for valid states. A legend at the bottom left defines the bit levels: 0 for Low bit, 1 for High bit, and grey for invalid data.](49ee89a1d5852ab005dbbab6de09a8a6_img.jpg) + +The diagram illustrates a sequence of 16-bit data words (D15 to D0) and a Mark bit over time. The vertical axis represents the data lines, and the horizontal axis represents time. The data is shown in two phases: an invalid phase (top) and a valid phase (bottom). The Mark bit indicates the validity of the data. A legend at the bottom left defines the bit levels: 0 for Low bit, 1 for High bit, and grey for invalid data, don't care. + +| Line | Invalid Phase | Valid Phase | Mark Bit | +|------|---------------|-------------|-------------------------| +| D15 | i n v a l d | d a t a | 0 0 1 0 1 0 1 0 1 0 0 0 | +| D14 | i n v a l d | d a t a | 0 1 1 1 1 | +| D13 | i n v a l d | d a t a | | +| D12 | i n v a l d | d a t a | | +| ⋮ | i n v a l d | d a t a | | +| D3 | i n v a l d | d a t a | | +| D2 | i n v a l d | d a t a | | +| D1 | i n v a l d | d a t a | | +| D0 | i n v a l d | d a t a | | + +Legend: + Invalid data, don't care (Grey) + 0 Low bit + 1 High bit + +T1519670-95/d02 + +Timing diagram showing 16-bit data flow (D15-D0) and a Mark bit over time. The diagram uses 'i', 'n', 'v', 'a', 'l', 'd' for invalid and 't', 'a', 'd' for valid states. A legend at the bottom left defines the bit levels: 0 for Low bit, 1 for High bit, and grey for invalid data. + +FIGURE 2/G.192 +**Example for a possible data flow in the DPI** + +While Figure 3 displays the interface from the point of view of two interconnected devices, Figure 4 displays the interface from a given device's point of view. There it can be seen where the algorithm resides, the data lines it is supposed to use, and how the other control signals are routed inside and through the given DPD. Examples are given in Figure 4 for 3 device setups. This figure is further described in 4.2. + +Currently only a TTL (Transistor-Transistor Logic) implementation of the basic hardware has been tested and used. Its description is given in Annex A. + +## 4.2 Master Clock and Reset + +The clock signal for devices interconnected by the DPI must be generated by only one device in the chain. This master clock in the simplest case is provided by the data source. In this case, only a clock line in the forward direction is necessary, i.e. from the data source towards the data sink through the interconnected devices. + +![Basic diagram for the hardware implementation of the DPI. The diagram shows a '25-p in connector male' on the left and a '25-p in connector female' on the right, connected by a 'Cable'. The male connector is labeled 'Transmitter side' and the female connector is labeled 'Receiver side'. The signals are: Voc (Vcc), Data (16-bit bus), Mark, Tx_Clks (Forward and Backwards), Rx_Clks, Reset, and Ground. The transmitter side contains a 'Register Set' for Data and Mark, and 'Line Driver' blocks for Data, Mark, Tx_Clks, and Reset. The receiver side contains 'Line Driver' blocks for Data, Mark, Tx_Clks, and Reset, and a 'Register Set' for Data and Mark. The Reset signal is driven by a 'Line Driver' with a 'Direction' input. The Data bus is labeled '16' at both ends. The Tx_Clks signal is labeled 'Forward' and 'Backwards' at the transmitter side. The Register Set on the transmitter side is connected to the Data and Mark signals. The Register Set on the receiver side is connected to the Data and Mark signals. The Line Drivers on the transmitter side are connected to the Data, Mark, Tx_Clks, and Reset signals. The Line Drivers on the receiver side are connected to the Data, Mark, Tx_Clks, and Reset signals. The Ground signal is connected to the Ground pin on both connectors.](3121ebddccf183ca63bb9781be440a7e_img.jpg) + +Basic diagram for the hardware implementation of the DPI. The diagram shows a '25-p in connector male' on the left and a '25-p in connector female' on the right, connected by a 'Cable'. The male connector is labeled 'Transmitter side' and the female connector is labeled 'Receiver side'. The signals are: Voc (Vcc), Data (16-bit bus), Mark, Tx\_Clks (Forward and Backwards), Rx\_Clks, Reset, and Ground. The transmitter side contains a 'Register Set' for Data and Mark, and 'Line Driver' blocks for Data, Mark, Tx\_Clks, and Reset. The receiver side contains 'Line Driver' blocks for Data, Mark, Tx\_Clks, and Reset, and a 'Register Set' for Data and Mark. The Reset signal is driven by a 'Line Driver' with a 'Direction' input. The Data bus is labeled '16' at both ends. The Tx\_Clks signal is labeled 'Forward' and 'Backwards' at the transmitter side. The Register Set on the transmitter side is connected to the Data and Mark signals. The Register Set on the receiver side is connected to the Data and Mark signals. The Line Drivers on the transmitter side are connected to the Data, Mark, Tx\_Clks, and Reset signals. The Line Drivers on the receiver side are connected to the Data, Mark, Tx\_Clks, and Reset signals. The Ground signal is connected to the Ground pin on both connectors. + +T1519680-95/d03 + +FIGURE 3/G.192 +**Basic diagram for the hardware implementation of the DPI** + +In other cases, as illustrated in Figure 4, the master clock may be a device somewhere in the chain. This could occur, for example, in connecting a codec to a real channel. In this situation the channel must provide the master clock and reset, and all other devices must synchronise to the channel. The channel has to generate clocks in the forward direction (Tx\_Clks) and in the backward direction (Rx\_Clks) through the chain. All devices in the chain must be configured to use either Rx\_Clks or Tx\_Clks, depending on where the master clock is located. See Figure 4 for an example configuration. + +The same holds for the reset signal, which a given device must derive either from its output interface (for devices before the master reset) or from its input interface (devices in forward direction). + +## 4.3 Timing, Timeslots and Capacity + +The data and mark bits are clocked out from the transmitter side on the rising edge of Tx\_Clks and clocked in at the receiver side on the falling edge of Tx\_Clks (see Figure 5). + +An “INterface TImeslot” (INTI) is defined as one clock period from rising edge to rising edge of the clock signal. Sixteen data bits, numbered D0 to D15, and one mark bit are transmitted by each INTI. INTIs with mark high (active high) are called “marked”, otherwise they are said to be “unmarked”. + +The functions of the interface are in principle independent from the clock rate, which can be as high as several MHz, constrained by cable lengths and the logic family of the integrated circuits used. For telephony codecs, a 16 kHz clock (Tx\_Clks) having a 50% duty cycle will be used in most cases. This gives in principle a total capacity of 256 kbit/s (16 bits × 16 kHz). + +If the master device is located within a chain of interconnected devices, as in Figure 4, then its input interface sends the Rx\_Clkl backwards in the chain. The neighbouring backwards device has to regenerate this clock signal and use it as Tx\_Clkl. Due to possible phase shifts between Rx\_Clkl and Tx\_Clkl, the data and mark bits shall always be triggered with the clock line in the forward direction, Tx\_Clkl. + +## 4.4 Reset procedure + +The reset signal /Reset is an active-low signal whose purpose is to synchronise all the devices in the chain. In normal operation, /Reset shall be inactive (high). The reset signal will be applied by the master reset (e.g. the data source or the channel) to the adjacent device(s) in the chain. For the reset procedure, the steps described below must be followed to guarantee the desired synchronisation. Figure 6 illustrates the signals during the reset procedure. + +The reset procedure is initiated by switching the reset signal /Reset to low (active) with the rising edge of Tx\_Clkl (same as Data and Mark bits). + +Every device in the chain has to receive the reset signal at its /Reset input and must regenerate and output the reset signal at its /Reset output (input and output may depend on the location of the master reset). + +All devices shall test the reset signal with the falling edge of Tx\_Clkl (same as data and mark bits) and start or continue their specific reset procedure when /Reset is active (low) at that time. + +The reset signal shall remain active for at least 16 clock cycles (1 ms for a 16 kHz clock) and be switched to inactive (high) with the rising edge of Tx\_Clkl. This is indicated in Figure 6. + +The source of data shall wait exactly for another 1600 clock cycles (100 ms for a 16 kHz clock) before the first INTI is marked to transmit the first valid data value (e.g. first sample to a speech encoder). This will be the available time for all devices in the chain to initialise properly and to be ready for processing. + +# 5 Hardware implementation + +## 5.1 Connector type, pin assignment and cabling + +At the transmitter side there is a 25 pin Sub-D male connector and at the receiver side there is a 25 pin Sub-D female connector. Table 1 shows the pin assignment for the digital parallel interface. + +It is advisable to use a cabling strategy that maximises noise rejection. For reducing the influence of noise, it is recommended to use twisted-pair parallel conductors with the pin assignment of Table 1. In this case, signals Mark, /Reset, Tx\_Clkl, and Rx\_Clkl should be twisted with ground especially in the case of regular to long cable lengths. + +## 5.2 Line drivers and receiver termination + +Because all data, mark, reset, and clock lines should be driven by equivalent line-drivers for the applied signalling voltage, there should be an adequate line termination to avoid reflections. The kind of termination will depend on the logic family. Annex A gives a specification for the TTL family. + +## 5.3 Distributed multiplexer + +The termination networks shall not be placed inside the receiving devices, but externally at the far end(s) of the cable. This makes possible the connection of more than one receiver to the same line, provided that only one is enabled at a given time, while the others are tri-stated. + +Both features together (external termination networks and tri-stated buffers) can be used to implement distributed multiplexers and demultiplexers. This function can be used, for example, for the randomisation of the speech material in subjective tests. + +![Schematic diagram of an Encoder, Channel model, and Decoder connected in series. Each block contains 'Data 16', 'Mark 1', and 'Processing' components. Clock signals (Tx_Clk, Rx_Clk) and Reset signals are shown. The Master Clock is located within the Channel model block. Data paths are labeled with widths 16 and 17. Reference T1519690-95/d04 is at the bottom right.](f4fdd410cdb84df81274da55721e56fb_img.jpg) + +The diagram illustrates a system architecture consisting of three main components connected in series: an Encoder, a Channel model, and a Decoder. Each component is enclosed in a dashed box. + +- Encoder:** Contains three main blocks. The first block has two inputs on the left (triangles) and two outputs on the right labeled "Data 16" and "Mark 1". The second block is labeled "Processing" and has two inputs on the left and two outputs on the right labeled "Data 16" and "Mark 1". The third block has two inputs on the left and two outputs on the right. A 17-bit wide data path (indicated by a slash and the number 17) connects the third block to the Channel model. +- Channel model:** Contains three main blocks. The first block has two inputs on the left and two outputs on the right labeled "Data 16" and "Mark 1". The second block is labeled "Processing" and has two inputs on the left and two outputs on the right labeled "Data 16" and "Mark 1". The third block has two inputs on the left and two outputs on the right. A 17-bit wide data path connects the third block to the Decoder. This block also contains a "Master Reset" block and a "Master Clock" block. The "Master Clock" is connected to the "Processing" block and the "Rx\_Clk" input. The "Master Reset" is connected to the "Reset" input. +- Decoder:** Contains three main blocks. The first block has two inputs on the left and two outputs on the right labeled "Data 16" and "Mark 1". The second block is labeled "Processing" and has two inputs on the left and two outputs on the right labeled "Data 16" and "Mark 1". The third block has two inputs on the left and two outputs on the right. + +Common signals are shown across the blocks: + +- Tx\_Clk:** Transmitted clock signal. It is generated in the Encoder and distributed to the Channel model and Decoder. +- Rx\_Clk:** Received clock signal. It is generated in the Channel model (from the Master Clock) and distributed to the Encoder and Decoder. +- Reset:** Reset signal. It is generated in the Channel model (from the Master Reset) and distributed to the Encoder and Decoder. + +Reference: T1519690-95/d04 + +Schematic diagram of an Encoder, Channel model, and Decoder connected in series. Each block contains 'Data 16', 'Mark 1', and 'Processing' components. Clock signals (Tx\_Clk, Rx\_Clk) and Reset signals are shown. The Master Clock is located within the Channel model block. Data paths are labeled with widths 16 and 17. Reference T1519690-95/d04 is at the bottom right. + +FIGURE 4/G.192 + Example for usage of the Rx\_Clk when the master clock lies inside the device chain – in this case, in the channel model + +![Timing diagram for INTI Interface Timeslot showing Marked INTI, Unmarked INTI, Sequence of marked INTIs, Tx_Clk, Data lines (D15..D0), and Mark bit. The diagram shows three distinct periods: a 'Marked INTI' period where the Mark bit is high, an 'Unmarked INTI' period where the Mark bit is low, and a 'Sequence of marked INTIs' where the Mark bit is high again. The Data lines (D15..D0) are shown as a single line with multiple transitions. The Tx_Clk signal is a periodic square wave. The Mark bit is a single line that goes high during the 'Marked INTI' and 'Sequence of marked INTIs' periods and low during the 'Unmarked INTI' period.](d48475a25698b1c0592e4cfe07138f2a_img.jpg) + +Timing diagram for INTI Interface Timeslot showing Marked INTI, Unmarked INTI, Sequence of marked INTIs, Tx\_Clk, Data lines (D15..D0), and Mark bit. The diagram shows three distinct periods: a 'Marked INTI' period where the Mark bit is high, an 'Unmarked INTI' period where the Mark bit is low, and a 'Sequence of marked INTIs' where the Mark bit is high again. The Data lines (D15..D0) are shown as a single line with multiple transitions. The Tx\_Clk signal is a periodic square wave. The Mark bit is a single line that goes high during the 'Marked INTI' and 'Sequence of marked INTIs' periods and low during the 'Unmarked INTI' period. + +INTI Interface Timeslot + +FIGURE 5/G.192 +Example of interface Timing + +![Timing diagram during the reset procedure (output of the source of data). The diagram shows the relationship between INTI, Tx_Clk, Reset, Data, and Mark signals over time. The INTI signal is shown as a series of pulses at indices 0, 1, 2, 16, 17, 18, and 1616. The Tx_Clk signal is a periodic square wave. The Reset signal is a single line that goes high at index 16. The Data signal is shown as 'Don't Care' from index 0 to 15 and 'Valid' from index 16 onwards. The Mark signal is shown as 'Don't Care' from index 0 to 15 and 'Valid' from index 16 onwards.](ff2492be4fa814905acbad18f261b8a5_img.jpg) + +Timing diagram during the reset procedure (output of the source of data). The diagram shows the relationship between INTI, Tx\_Clk, Reset, Data, and Mark signals over time. The INTI signal is shown as a series of pulses at indices 0, 1, 2, 16, 17, 18, and 1616. The Tx\_Clk signal is a periodic square wave. The Reset signal is a single line that goes high at index 16. The Data signal is shown as 'Don't Care' from index 0 to 15 and 'Valid' from index 16 onwards. The Mark signal is shown as 'Don't Care' from index 0 to 15 and 'Valid' from index 16 onwards. + +FIGURE 6/G.192 +Timing during the reset procedure (output of the source of data) + +Additional functionality can be added to the DPI by using pins 22, 23, and 24 as device address lines, instead of being grounded. This extended configuration allows the interface to be used as a simple data bus. Because these lines would usually represent ground twisted with the clock lines, this may introduce a loss in noise rejection1). The advantages of the use of address lines are the automatic selection by the data source of one out of several devices in a distributed multiplex configuration. + +To allow downward compatibility with existing devices, the address 0 shall be defined as “all devices selected” because this is electrically equivalent as having pins 22, 23, and 24 as ground. There is therefore address space for up to seven different devices in a multiplex configuration. Address line A0 is assigned to pin 24, A1 to pin 23, and A2 to pin 22. + +1) Further study is necessary in this topic to determine environmental and cabling conditions to assure reliable operation. + +TABLE 1/G.192 + +### Pin assignment for the Digital Parallel Interface + +| Pin | Signal name | Pin | Direction | Pin | Signal name | Pin | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|----------|--------------------------------------------------------------------|----------------|-------------|---------------| +| 14 | D14 | D15 | 1 | → | 1 | D15 | +| | | D13 | 2 | → | 2 | D13 | +| 15 | D12 | | | | | D12 | +| | | D11 | 3 | → | 3 | D11 | +| 16 | D10 | | | | | D10 | +| | | D9 | 4 | → | 4 | D9 | +| 17 | D8 | | | | | D8 | +| | | D7 | 5 | → | 5 | D7 | +| 18 | D6 | | | | | D6 | +| | | D5 | 6 | → | 6 | D5 | +| 19 | D4 | | | | | D4 | +| | | D3 | 7 | → | 7 | D3 | +| 20 | D2 | | | | | D2 | +| | | D1 | 8 | → | 8 | D1 | +| 21 | D0 | | | | | D0 | +| | | Mark | 9 | → | 9 | Mark | +| 22 | Ground/A2 | | | | | A2/Ground | +| | | /Reset | 10 | Gnd/→
(←) → | 10 | /Reset | +| 23 | Ground/A1 | | | | | A1/Ground | +| | | Tx_Clk | 11 | Gnd/→
→ | 11 | Tx_Clk | +| 24 | Ground/A0 | | | | | A0/Ground | +| | | Rx_Clk | 12 | Gnd/→
← | 12 | Rx_Clk | +| 25 | Ground | | | | | Ground | +| | | +5 V/2 Ω | 13 | | 13 | Not connected | +| Digital Output Interface
Male connector
view onto the pins | | | Digital Input Interface
Female connector
view onto the holes | | | | +| D15-D0 16 data bit in parallel (D15 = MSb; D0 = LSb)
A2-A0 Optional 3-bit address running in the forward direction
Mark Additional bit for special purposes
Tx_Clk Forward direction clock signal
Rx_Clk Backwards direction clock signal
/Reset Low-active reset signal to/from that device
+5 V/2 Ω Power supply for the termination network with a 2 Ω series resistance
Gnd/→ Either ground connection or the address line in the forward direction | | | | | | | + +![Diagram of a 25-pin male connector. The top row contains pins 1 through 13, labeled with signal names: D15, D13, D11, D9, D7, D5, D3, D1, M, /R, Tx, Rx, V. The bottom row contains pins 14 through 25, labeled with signal names: D14, D12, D10, D8, D6, D4, D2, D0, GA2, GA1, GA0, G. A legend below the diagram defines the abbreviations: M Mark, /R /Reset, Tx Transmit clock, Rx Receive clock, V Power, G ground. The text '(Male connector)' is centered below the legend.](27b06ec9f42b5d727a2630f61a5f1861_img.jpg) + +T15 19720-95/d07 + +M Mark    /R /Reset    Tx Transmit clock    Rx Receive clock +V Power    G ground +(Male connector) + +Diagram of a 25-pin male connector. The top row contains pins 1 through 13, labeled with signal names: D15, D13, D11, D9, D7, D5, D3, D1, M, /R, Tx, Rx, V. The bottom row contains pins 14 through 25, labeled with signal names: D14, D12, D10, D8, D6, D4, D2, D0, GA2, GA1, GA0, G. A legend below the diagram defines the abbreviations: M Mark, /R /Reset, Tx Transmit clock, Rx Receive clock, V Power, G ground. The text '(Male connector)' is centered below the legend. + +The address lines are active all the time, and the devices shall check the selection every falling edge of the Tx\_Clk, and the data source shall change it on the rising edge of the Tx\_Clk of an unmarked INTI. Unselected devices can either continue running as if the input is zero-valued, or just freeze. This is for further study. + +In the case these lines are used as address bits, they shall be buffered and have terminations as done for the data, mark, clock, and reset lines, always in the forward direction, as indicated in Table 1. If this feature is not used, these lines should be directly connected from the input to the output of the device. + +## 5.4 Signal delays within devices + +Devices which receive data at their input, process them and deliver data at their output, must handle the clocks and the reset signal in the way described, to ensure proper operation in the complete chain of devices. + +The clock signals Tx\_Clk and Rx\_Clk and the reset signal /Reset must be regenerated inside the devices and forwarded at the other end. The delay for these signals within the device shall be as low as possible (e.g. as low as the delay of two SN74LS245, i.e. up to 20 ns). This will guarantee proper phase relationship between all signals in practical applications and will simplify the timing for interconnecting master and slave devices. + +# Annex A + +## DPI implementation using TTL logic integrated circuits + +(This annex forms an integral part of this Recommendation) + +Figure A.1 shows the hardware implementation of the DPI from the point of view of interconnected devices using standard TTL (Transistor-Transistor Logic) integrated circuits. + +All data, mark and clock lines are driven by simple TTL-drivers of type SN74LS245. For the parallel data register a SN74LS273 is used. Equivalent integrated circuit types may be used, but care has to be taken in this case. + +The 5 V/2 Ω power supply is provided by the transmitter for the sole purpose of feeding the line termination network at the receiver side. Since termination networks are external to the interface, this line shall not be connected electrically on the receiver side. + +A special kind of cable termination is needed to avoid signal reflections. For cable lengths between 2 and 10 meters, all lines shall terminate at the destination (receiving) end of the signal with a passive network of 330/470 Ω to +5 V/Ground respectively. This is the reason why, in Figure A.1, all the signals in the forward direction are terminated at the receiver's side, while the only backward-direction signal, Rx\_Clk, is terminated at the transmitter's side. + +For short cable lengths (less than 2 meters) the termination may be omitted. For very long cables (more than 10 meters), termination networks may be necessary at both ends of the lines. + +SW1 in Figure A.1 connects Tx\_Clk to the position labelled forward when the transmitter side of a DPD is in the forward direction, and to the position labelled backward when the transmitter side is in the backwards direction respective to the master clock. See Figure 4 for connection examples. + +Signals Dir and $\overline{G}_R$ are generated internally by each DPD in the chain. Signal Dir indicate whether the DPD is in the forward direction ('0') or in the backwards direction ('1'). Signal $\overline{G}_R$ is an active-low signal that defines whether the DPD is enabled or disabled. $\overline{G}_R$ is generated from the address lines if the bus mode of the DPI is used. If the bus mode feature is not to be used, $\overline{G}_R$ shall be connected to ground. + +To help understand the description of the interface, the DPI is described in Figures A.2A and A.2B for a given DPD. Figure A.2A describes the DPI implementation for a device which is not a master clock/reset. This device will be operating in the forward direction if switch SW1 is in position F and in the backward direction if it is in position B. Figure A.2B describes the DPI implementation for a master-clock-and-reset device. + +![Basic configuration hardware interface diagram for two interconnected DPT. The diagram shows a Transmitter side and a Receiver side connected by a Cable. The Transmitter side includes a 2 Ω resistor on the +5 V line, a Data 17 bus (pins ...273) with Mark signal, a Direction switch (SW1) for Forward and Backward directions, Tx_Clk and Rx_Clk signals, an /Reset signal, and an optional Address Decode block for a 3-bit Address bus (pins ...245). The Receiver side includes a Data 17 bus (pins ...273) with Mark signal, Tx_Clk and Rx_Clk signals, an /Reset signal, and an optional Address Decode block for a 3-bit Address bus (pins ...245). The Cable contains 17 data lines, 1 Tx_Clk line, 1 Rx_Clk line, 1 /Reset line, and 3 Address lines. Termination resistors (330 Ω and 470 Ω) are shown on the cable lines. A note indicates that the +5 V line is not connected on the Receiver side (only used for cable terminations).](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +Basic configuration hardware interface diagram for two interconnected DPT. The diagram shows a Transmitter side and a Receiver side connected by a Cable. The Transmitter side includes a 2 Ω resistor on the +5 V line, a Data 17 bus (pins ...273) with Mark signal, a Direction switch (SW1) for Forward and Backward directions, Tx\_Clk and Rx\_Clk signals, an /Reset signal, and an optional Address Decode block for a 3-bit Address bus (pins ...245). The Receiver side includes a Data 17 bus (pins ...273) with Mark signal, Tx\_Clk and Rx\_Clk signals, an /Reset signal, and an optional Address Decode block for a 3-bit Address bus (pins ...245). The Cable contains 17 data lines, 1 Tx\_Clk line, 1 Rx\_Clk line, 1 /Reset line, and 3 Address lines. Termination resistors (330 Ω and 470 Ω) are shown on the cable lines. A note indicates that the +5 V line is not connected on the Receiver side (only used for cable terminations). + +T1519730-95/d08 + +FIGURE A.1/G.192 + +**Basic configuration hardware interface diagram for two interconnected DPT – +The address lines of the extended configuration are optional (see main body of this +Recommendation for details) – Signals Dir and $\overline{G_R}$ are generated by each DPD in the chain** + +![Basic configuration hardware interface diagram for a given DPD. The diagram shows a 'Receiving side' on the left and a 'Transmitting side' on the right, separated by a 'Ground' line. Key components include: 'Incoming power not used by DPD' on the far left; 'Data/Mark bits latched in on falling edge of Tx_Clk' (labeled ...273) and 'Data/Mark bits latched out on rising edge of Tx_Clk' (labeled ...273) connected to a central 'Processing' block; 'Tx_Clk' and 'Rx_Clk' lines with directional switches (A/B, Dir, G_R); a switch 'SW1' with positions 'F' and 'B' for 'Dir'; '/Reset' lines with directional switches; an 'Optional' 'Address' bus with an 'Address Decode' block; and a '+5 V' supply with a 2Ω resistor on the transmitting side. Various bus widths are indicated: ...245, ...273, Data 17, Mark, 3, and G_R.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +Basic configuration hardware interface diagram for a given DPD. The diagram shows a 'Receiving side' on the left and a 'Transmitting side' on the right, separated by a 'Ground' line. Key components include: 'Incoming power not used by DPD' on the far left; 'Data/Mark bits latched in on falling edge of Tx\_Clk' (labeled ...273) and 'Data/Mark bits latched out on rising edge of Tx\_Clk' (labeled ...273) connected to a central 'Processing' block; 'Tx\_Clk' and 'Rx\_Clk' lines with directional switches (A/B, Dir, G\_R); a switch 'SW1' with positions 'F' and 'B' for 'Dir'; '/Reset' lines with directional switches; an 'Optional' 'Address' bus with an 'Address Decode' block; and a '+5 V' supply with a 2Ω resistor on the transmitting side. Various bus widths are indicated: ...245, ...273, Data 17, Mark, 3, and G\_R. + +FIGURE A.2A/G.192 + +**Basic configuration hardware interface diagram for a given DPD when the device is not the master clock/reset – If switch SW1 is in position B, the device will be operating in the backward direction, and SW1 is in position F, the DPD will be operating in the forward direction** + +![Basic configuration hardware interface diagram for a master clock/reset DPD. The diagram shows a 'Receiving side' on the left and a 'Transmitting side' on the right, separated by a central 'Processing' block. The receiving side includes a 245 transceiver, a 273 flip-flop for latching 'Data 17' and 'Mark' bits on the falling edge of 'Tx_Clkl', and a 245 transceiver for 'Address' signals. The transmitting side includes a 273 flip-flop for latching 'Data 17' and 'Mark' bits on the rising edge of 'Tx_Clkl', and a 245 transceiver for 'Address' signals. A 'Master Clock' block generates 'Tx_Clkl' and 'Rx_Clkl' signals. A 'Master Reset' block generates the '/Reset' signal. An 'Address Decode' block takes a 3-bit 'Address' signal and generates the active-low signal 'G_R'. Power pins are shown on the left (incoming power not used by DPD) and right (+5 V and 2 ohm resistor). A 'Ground' line is shown at the bottom. Various signal names like 'Dir', 'A', 'B', and 'G_R' are present on the transceivers.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Basic configuration hardware interface diagram for a master clock/reset DPD. The diagram shows a 'Receiving side' on the left and a 'Transmitting side' on the right, separated by a central 'Processing' block. The receiving side includes a 245 transceiver, a 273 flip-flop for latching 'Data 17' and 'Mark' bits on the falling edge of 'Tx\_Clkl', and a 245 transceiver for 'Address' signals. The transmitting side includes a 273 flip-flop for latching 'Data 17' and 'Mark' bits on the rising edge of 'Tx\_Clkl', and a 245 transceiver for 'Address' signals. A 'Master Clock' block generates 'Tx\_Clkl' and 'Rx\_Clkl' signals. A 'Master Reset' block generates the '/Reset' signal. An 'Address Decode' block takes a 3-bit 'Address' signal and generates the active-low signal 'G\_R'. Power pins are shown on the left (incoming power not used by DPD) and right (+5 V and 2 ohm resistor). A 'Ground' line is shown at the bottom. Various signal names like 'Dir', 'A', 'B', and 'G\_R' are present on the transceivers. + +FIGURE A.2B/G.192 + +**Basic configuration hardware interface diagram for a master clock/reset DPD – This device will generate the forward clock (Tx\_Clkl) – and backward clock (Rx\_Clkl), as well as the /Reset signal, for the interconnected DPD – The Tx\_Clkl used by the Master DPD comes from the preceding DPD, which has regenerated Rx\_Clkl as its Tx\_Clkl** + +# Annex B + +## Data formats + +(This annex forms an integral part of this Recommendation) + +The DPI is capable of transporting different data structures between different devices without any changes in the physical and electrical specifications. However, different data formats and protocols have to be defined for higher layer operation. + +Currently, only two types of data are defined: time signals (representing, e.g. speech samples) and coded bitstreams (representing, e.g. codec parameters). The following is the description of the structure of these data types. + +## B.1 Time signals + +Time signals shall be transported in the format described below at the input of an encoder and the output of a decoder. This guarantees that different interconnection configurations can be used. + +The data representation is a left-justified, 16-bit 2's complement format, i.e. the most significant bit is always bit D15. If a bit resolution b other than 16-bit is required, the (16-b) least-significant bits shall be set to zero. This is also the convention adopted for the integer number representation by the ITU-T Software Tool Library defined in Recommendation G.191. + +The sampling frequency should be set to 8 kHz for the general case of telephony codecs. It should be noted that the sampling frequency is independent of the clock-rate signal (Tx\_Clks or Rx\_Clks) and can be higher than the sampling rate (e.g. 16 kHz for a telephony codec). + +Whenever a sample is transported by means of the digital interface, the mark bit is set (high). + +The data structure of a sampled data is defined by a marked INTI always followed by an unmarked INTI. This is done to allow real-time processing by the devices in the chain during speech sentences. Multiple unmarked INTIs in a row are only allowed between completely processed materials (e.g. between the end of a speech file and the start of the next one), because at that time there will be no time signals to be transported by the DPI. This simplifies the data handling inside the data source and the data sink. Further data structuring for the DPI time signal representation is not required at this level. See Figures B.1 and B.2. + +As described above, after applying the reset procedure, the encoder receives the first sample from the data source. All other samples will follow in the defined data structure, until the processing of the whole data is terminated. Figure B.1 illustrates a possible data flow where each sample has a 13-bit resolution. + +NOTE – For objective measurements (such as for voiceband data) the data source and sink can be an A/D and D/A converter device. This will use exactly the same data format. Also, the data format makes it possible to connect the data source directly to the data sink, e.g. for hardware verification purposes. + +![Timing diagram showing data flow for speech stimulus 'm', a gap, and stimulus 'm+1'. It displays 16-bit data words (D15-D0) and a 1-bit Mark signal over time. The diagram shows three samples of 13-bit resolution data, left-justified in 16-bit words. The first sample for stimulus 'm' has bits d, d, d, d, ..., d, 0, 0, 0. The second sample (Gap) has bits d, d, d, d, ..., d, 0, 0, 0. The third sample for stimulus 'm+1' has bits d, d, d, d, ..., d, 0, 0, 0. The Mark signal is shown as a series of pulses: 0 0 1 0 1 0 1 0 for the first sample, 1 0 0 0 1 0 1 Mark for the second, and 0 1 0 1 Mark for the third. Gray shaded areas indicate invalid data.](67518cfe156890dac13b5e67abd10dc1_img.jpg) + +Legend: + +- Invalid data, don't care (gray box) +- 0 Low bit +- 1 High bit + +T1519760-95/d11 + +Timing diagram showing data flow for speech stimulus 'm', a gap, and stimulus 'm+1'. It displays 16-bit data words (D15-D0) and a 1-bit Mark signal over time. The diagram shows three samples of 13-bit resolution data, left-justified in 16-bit words. The first sample for stimulus 'm' has bits d, d, d, d, ..., d, 0, 0, 0. The second sample (Gap) has bits d, d, d, d, ..., d, 0, 0, 0. The third sample for stimulus 'm+1' has bits d, d, d, d, ..., d, 0, 0, 0. The Mark signal is shown as a series of pulses: 0 0 1 0 1 0 1 0 for the first sample, 1 0 0 0 1 0 1 Mark for the second, and 0 1 0 1 Mark for the third. Gray shaded areas indicate invalid data. + +FIGURE B.1/G.192 +**Example of a time signal representing a sampled data with 13-bit resolution (left-justified)** + +![Diagram of a coded bitstream signal showing synchronization words, stimulus data, and a gap. The diagram is divided into three main sections: 'Stimulus "m"', 'Gap', and 'Stimulus "m+1"'. Each section contains a 'sync' word, a 'word' length indicator, and 'k' data bits. The 'sync' words are '00111111' and '00111111'. The 'word' length indicators are '123' and '123'. The data bits are labeled D15 through D00. A 'Mark' bit is shown at the end. A legend indicates that grey cells are 'Invalid data, don't care', '0' is 'Low bit', and '1' is 'High bit'.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Invalid data, don't care +0 Low bit +1 High bit + +Diagram of a coded bitstream signal showing synchronization words, stimulus data, and a gap. The diagram is divided into three main sections: 'Stimulus "m"', 'Gap', and 'Stimulus "m+1"'. Each section contains a 'sync' word, a 'word' length indicator, and 'k' data bits. The 'sync' words are '00111111' and '00111111'. The 'word' length indicators are '123' and '123'. The data bits are labeled D15 through D00. A 'Mark' bit is shown at the end. A legend indicates that grey cells are 'Invalid data, don't care', '0' is 'Low bit', and '1' is 'High bit'. + +FIGURE B.2/G.192 + +Example of a coded bitstream signal representing a data frame of k softbits, preceded by a synchronization word and its length k (all right-justified) + +## B.2 Coded bitstream + +When DPDs are implementations of the encoder portion of a codec, their output DPI will represent a coded bitstream. The same happens with the input DPI of a DPD implementing a decoder. + +In order to enable the DPI to transport different bitstream formats without electrical or physical changes, it is necessary to define a flexible format. + +Each bit of the bitstream data is represented as a 16-bit word, preceded by a synchronization word and a frame length word. This enables the implementation of the concept of “softbits”, what permits easy introduction of synchronisation words in the bitstream, and allows for the use of probabilistic models to hit samples or frames by errors of several types (e.g. random, burst, as well as frame erasure errors). + +The recommended definition for the softbits is given in the ITU-T Software Tool Library Manual. The bits out of an encoder are coded as 256-level softbit words. A bit '0' is coded as the softbit 0x007F and a bit '1' as the softbit 0x0081. Data at the decoder with these values are taken as correct, while other values in the range of 0..255 are taken as samples with an associated chance of being in error. The (hard) information of the softbit can be seen in the MSb of the 8-bit softbit data. Softbits in the range 0x6B21..0x6B2F are used as synchronisation words. The four LSbs of the synchronisation words are used to distinguish between the different kinds of synchronisation words that may appear in a system. A synchronisation word of 0x6B20 is the bad-frame indicator. The length word is always right-adjusted and its value will depend on the frame size and on the codec data rate. For example, the length word will be 80 (0x0050) for an 8 kbit/s codec with a frame size of 10 ms. + +Figure B.2 illustrates a coded bitstream layout, where the bitstream has k (soft) bits and every frame is preceded by a synchronisation word and its length k (all right-justified). + +# Annex C + +## Rules for codec implementation + +(This annex forms an integral part of this Recommendation) + +As described in Annex B, an undefined number of unmarked INTIs may occur at the digital output interface of the digital data source at any time, in order to simplify the file handling inside the data source and sink. Therefore, an encoder in the chain must not synchronise to the Tx\_Clk (which will be a continuously running clock, providing the transport medium), but rather to the Mark bit at its input (see Figure 4). For every received Mark bit another sample has to be shifted into the input buffer of the encoder and processed according to the encoding algorithm. + +The encoder output must transmit only valid and complete encoded frames. The Mark bit must be set accordingly as illustrated in Figure B.2. + +To guarantee proper start up after reset and to keep the delay to a minimum, all variables within the encoder should be reinitialised during the reset procedure. Reinitialising means setting all variables to values as if there would have been a 0-sample input sequence for an infinitely long time before the first sample from the control system or conditioning device is received. Possible exceptions to this rule are variables defined by the implementor as having a special initial reset value at the encoder. + +Devices that manipulate the encoded frame bitstream (e.g. error insertion devices) may introduce short delays of a few INTIs in the processing chain in order to synchronise their operation with a synchronisation word in the bitstream. + +Similarly to the encoder, the decoder must synchronise to the Mark bit at its input interface, process the received encoded word or frame and output its first valid sample when it is available. Before this event, only unmarked INTIs must be generated. The decoder should assume again an infinitely long sequence on “encoded silence” (0-sample sequence) before the first valid bitstream is received after reset. Again, possible exceptions to this rule are variables defined by the implementor as having a special initial reset value at the decoder. The decoder has to ensure that within a given speech stimulus (e.g. a speech file provided by a computer acting as data source), data will be output every other INTI without gaps (see Figure B.1). + +# NOTES + +1 This synchronisation protocol allows for real-time measurements using A/D and D/A converters, such as for voiceband data performance evaluation. The data sink will take the first sample emerging from the output of the decoder as the response to the first sample at the input of the encoder. + +2 By measuring the time interval between these two instants, one can derive an estimate of the signal delay for the chain “encoder, bit-manipulation devices and decoder”. + +# Annex D + +## Example host laboratory test configurations + +(This annex forms an integral part of this Recommendation) + +In general, in a test configuration there will be a control system that issues control signals to the interconnected devices, what also operates as the source and sink of data. The interconnected devices may be, for example, an encoder and its decoder connected by a hardware model of the transmission channel. This is represented in Figure D.1 a). + +Another configuration could be to have a signal conditioning device in between the control system and the codec, in order to perform pre- and post-processing of the source and sink data, respectively. This configuration is shown in Figure D.1 b). + +When measuring the performance of a system for analogue signals, it may be necessary that the source of data be an A/D converter, and the sink of data a D/A converter. This is the case for carrying out voiceband data measurements. This is shown in Figure D.1 c). + +The interface of this Recommendation has been defined to be flexible enough to accommodate a wide range of configurations that usually appear in the evaluation processes of ITU-T standardisation activities. + +![Diagram (a) shows a configuration without a signal conditioning device. A 'Data Source' and 'Data Sink' are connected to a 'Control System'. The 'Control System' is connected to an 'Encoder' and a 'Decoder' (both part of a 'Codec'). The 'Encoder' and 'Decoder' are connected to a 'Channel' via digital parallel interface paths (circles).](83852ec55d4802521a727926336bedab_img.jpg) + +Diagram (a) shows a configuration without a signal conditioning device. A 'Data Source' and 'Data Sink' are connected to a 'Control System'. The 'Control System' is connected to an 'Encoder' and a 'Decoder' (both part of a 'Codec'). The 'Encoder' and 'Decoder' are connected to a 'Channel' via digital parallel interface paths (circles). + +a) Configuration without a signal conditioning device + +![Diagram (b) shows a configuration with a signal conditioning device. A 'Data Source' and 'Data Sink' are connected to a 'Control System'. The 'Control System' is connected to 'Pre-processing' and 'Post-processing' (both part of a 'Signal Conditioning' device). The 'Signal Conditioning' device is connected to an 'Encoder' and a 'Decoder' (both part of a 'Codec'). The 'Encoder' and 'Decoder' are connected to a 'Channel' via digital parallel interface paths (circles). The entire 'Data Source', 'Data Sink', 'Control System', and 'Signal Conditioning' block is labeled 'Data source and sink', as seen by the Codec.](81a4cbf0b3c4cbc065efdf8f800dadde_img.jpg) + +Diagram (b) shows a configuration with a signal conditioning device. A 'Data Source' and 'Data Sink' are connected to a 'Control System'. The 'Control System' is connected to 'Pre-processing' and 'Post-processing' (both part of a 'Signal Conditioning' device). The 'Signal Conditioning' device is connected to an 'Encoder' and a 'Decoder' (both part of a 'Codec'). The 'Encoder' and 'Decoder' are connected to a 'Channel' via digital parallel interface paths (circles). The entire 'Data Source', 'Data Sink', 'Control System', and 'Signal Conditioning' block is labeled 'Data source and sink', as seen by the Codec. + +b) Configuration with a signal conditioning device + +![Diagram (c) shows a configuration with signal source from an A/D converter. 'Analogue Signals' are input to an 'A/D' converter. The 'A/D' converter is connected to 'Pre-processing' and 'Post-processing' (both part of a 'Signal Conditioning' device). The 'Signal Conditioning' device is connected to an 'Encoder' and a 'Decoder' (both part of a 'Codec'). The 'Encoder' and 'Decoder' are connected to a 'Channel' via digital parallel interface paths (circles). The 'D/A' converter is connected to the 'Post-processing' and outputs 'Analogue Signals'. The entire 'A/D', 'D/A', 'Pre-processing', 'Post-processing', and 'Signal Conditioning' block is labeled 'Data source and sink', as seen by the Codec.](3da1a07cb87051bf616c9876db958cf0_img.jpg) + +Diagram (c) shows a configuration with signal source from an A/D converter. 'Analogue Signals' are input to an 'A/D' converter. The 'A/D' converter is connected to 'Pre-processing' and 'Post-processing' (both part of a 'Signal Conditioning' device). The 'Signal Conditioning' device is connected to an 'Encoder' and a 'Decoder' (both part of a 'Codec'). The 'Encoder' and 'Decoder' are connected to a 'Channel' via digital parallel interface paths (circles). The 'D/A' converter is connected to the 'Post-processing' and outputs 'Analogue Signals'. The entire 'A/D', 'D/A', 'Pre-processing', 'Post-processing', and 'Signal Conditioning' block is labeled 'Data source and sink', as seen by the Codec. + +c) Configuration with signal source from an A/D converter + +T1519780-95/d13 + +FIGURE D.1/G.192 + +Example reference configurations for interconnecting devices using the digital parallel interface – The circles represent the digital parallel interface data paths and the squares a potentially specialised, high-performance interface (as used in the ITU-T 8 kbit/s codec Host Laboratory) + +## Appendix I + +### The ITU-T 8 kbit/s speech codec test parallel interface + +(This appendix does not form an integral part of this Recommendation) + +It was decided to use a full digital approach in the host laboratory session for the evaluation of the subjective speech quality of codec candidates for the ITU-T 8 kbit/s coder selection test. + +In the hardware setup used by the host laboratory, the “Host Laboratory Control System” (HLCS) was used as data source and data sink. The HLCS sends out stimulus data (test sentences) by means of a “Signal Conditioning Device” (SCD) to the (speech and channel) encoder under test and collect the output of the (speech and channel) decoder (resynthesised speech). Selection of stimulus data, control of the SCD and the “Error Insertion Device” (EID), and randomisation of processed sentences are done by software inside the HLCS. The error insertion device was used to implement the radio channel model. + +Figure I.1 gives an overview and shows the devices in the chain of the data flow. + +All interfaces at the inputs and outputs of the codec candidate under test, illustrated in Figure I.1, are completely digital and of the same type. + +![Figure I.1/G.192: Data flow for host laboratory session diagram.](812b773680b611c18d49243e102b895a_img.jpg) + +Detailed description of Figure I.1: This block diagram shows the data flow between various components. On the left is a large box labeled 'Host Laboratory Control System (HLCS)'. Arrows point from the HLCS to a 'Specialized Interface' which leads into a dashed box labeled 'Signal Conditioning Device (SCD)'. Inside the SCD, there are 'Pre-processing' and 'Post-processing' blocks. From 'Pre-processing', data flows into the 'Codec under test' dashed box, specifically to the 'Encoder'. The output of the 'Encoder' goes through a 'Digital Parallel Interface' to an 'Error Insertion Device'. The 'Error Insertion Device' is also connected to the HLCS via an 'RS-232' line. The output of the 'Error Insertion Device' returns to the 'Decoder' inside the 'Codec under test' box. The 'Decoder' output goes to 'Post-processing' in the SCD, and finally back to the HLCS. Below the SCD, three vertical boxes labeled 'Sample' are shown. Below the 'Error Insertion Device', a bitstream structure is shown starting with 'Sync', then '80', 'SB1', '...', and 'SB80'. + +Figure I.1/G.192: Data flow for host laboratory session diagram. + +FIGURE I.1/G.192 +**Data flow for host laboratory session** + +#### I.1 Specialisation of the interface + +The host laboratory for the selection tests of the ITU-T G.729 8 kbit/s speech coder used the DPI defined in this Recommendation. Not all functions of this interface were necessary in the host laboratory sessions of the codec selection and of the codec characterisation tests. + +To simplify the interface as much as possible, the following specialisations were defined: + +- i) Only one transmitter was connected to only one receiver. No distributed multiplexing was used. All line drivers at the transmitter and receiver side were always enabled. +- ii) Only Tx\_Clk was used throughout the tests; Rx\_Clk was not used (the HLCS device was the master clock source). + +**Recommendation G.192 (03/96)**      17 + +- iii) /Reset was used only in the forward direction (the HLCS was the master reset source). +- iv) Only marked INTIs held valid data. The data bits in unmarked INTIs were set to '0' at the transmitter side and were not considered at the receiver side. +- v) The source and sink of data was the HLCS/SCD (for processing of the speech material) or equivalent A/D and D/A converters (for objective measurements with voiceband data). + +## I.2 Data formats + +**Time signals.** The 8 kbit/s coder selection host laboratory configuration used the time signal format between the SCD and the codecs under test. + +**Bitstream signals.** For the signals between the EID and the codecs under test, a bitstream format with length word equal to 80 (01010000 in binary) was used. This bitstream format is illustrated in Figure I.2. In the event of frame erasures, the EID did not change the synchronisation word 0x6B21 to 0x6B20, but changed all the softbits in the frame to 0x0000 to indicate loss of information. + +Both definitions allowed the bypassing of the EID or of the codecs, for verification of the adequate operation of the system. + +![Timing diagram showing the channel signal for an 8 kbit/s codec. It displays two frames, 'Frame m' and 'Frame m+1', separated by a 'Gap'. Each frame contains 16 bits (D15 to D00). The bits are organized into columns: 'sync word' (8 bits), 'soft bits' (8 bits), and a 'Mark' bit. The 'sync word' bits are 00111111 for Frame m and 11111111 for Frame m+1. The 'soft bits' are grouped into four sets of four bits each. A legend at the bottom left indicates that grey cells are 'Invalid data, don't care', '0' is 'Low bit', and '1' is 'High bit'. The diagram is labeled T1519800-95/d15.](7d3d5fb5d09c0cd35a9d637be241651e_img.jpg) + +Timing diagram showing the channel signal for an 8 kbit/s codec. It displays two frames, 'Frame m' and 'Frame m+1', separated by a 'Gap'. Each frame contains 16 bits (D15 to D00). The bits are organized into columns: 'sync word' (8 bits), 'soft bits' (8 bits), and a 'Mark' bit. The 'sync word' bits are 00111111 for Frame m and 11111111 for Frame m+1. The 'soft bits' are grouped into four sets of four bits each. A legend at the bottom left indicates that grey cells are 'Invalid data, don't care', '0' is 'Low bit', and '1' is 'High bit'. The diagram is labeled T1519800-95/d15. + +FIGURE I.2/G.192 +**Channel signal representing the 8 kbit/s codec encoded bitstream + for a 10 ms speech frame length** + +# References + +- ITU-T Recommendation G.191 (1993), *Software tools for speech and audio coding standards.* +- ITU-T Recommendation G.729 (1996), *Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear-prediction (CS-ACELP).* \ No newline at end of file diff --git a/marked/G/T-REC-G.221-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.221-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.221-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.221-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.221-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..41cd1fad608b679f66101671c553e1e9a5f424dd --- /dev/null +++ b/marked/G/T-REC-G.221-198811-I_PDF-E/raw.md @@ -0,0 +1,86 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.221** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS** + +## --- **OVERALL RECOMMENDATIONS RELATING TO CARRIER-TRANSMISSION SYSTEMS** + +**ITU-T Recommendation G.221** + +(Extract from the *Blue Book*) + +--- + +### NOTES + +1 ITU-T Recommendation G.221 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +#### Recommendation G.221 + +## OVERALL RECOMMENDATIONS RELATING TO CARRIER-TRANSMISSION SYSTEMS + +(amended at Geneva, 1972 and 1980) + +### 1 Characteristics of complete circuits + +The characteristics of complete circuits, measured between audio-frequency terminals (overall loss in terminal service and in transit service, frequency bands effectively transmitted and attenuation distortion, variation of overall loss with time, phase distortion, stability, crosstalk, etc.) should meet the general conditions for 4-wire telephone circuits indicated in Section 1 of the Series G Recommendations. + +### 2 Linear crosstalk + +#### 2.1 Overall requirements + +The requirements as regards crosstalk ratio between circuits in the case of telephony are the subjects of Recommendation G.134 [1] and the Recommendation cited in [2]; for go-to-return crosstalk the Recommendation cited in [3] applies. + +As carrier transmission systems are also used for setting up sound-programme circuits, the relevant requirements given in the Series J Recommendations should be taken into consideration. Recommendation J.18 [4] gives general guidance on how the higher crosstalk ratios appropriate to sound-programme transmissions are achieved in a telephone network. + +In any case the near-end crosstalk ratio between the two directions of transmission at all frequencies used for the regulating and measuring pilots on carrier systems should be not less than 40 dB. + +#### 2.2 Intelligible crosstalk caused by intermodulation with a signal which is a multiple of 4 kHz + +Intelligible crosstalk may arise between circuits by way of intermodulation with a signal which is a multiple of 4 kHz, e.g. a line-regulating pilot. A design objective is that the intelligible crosstalk ratio in a single homogeneous section of the appropriate hypothetical reference circuit should be not less than 74 dB. + +### 3 Noise transmitted between interconnected systems + +A failure or malfunction in a chain of repeaters may lead to large values of noise in one or several signal bands being transmitted by that chain. It is known that such high noise levels are generally caused by the operation of particular types of automatic line regulators. Given that such high noise levels may be transmitted to other chain links, and may overload those to which they are interconnected, it is desirable and recommended that care should be taken in the future in order to avoid such troubles. + +Possible methods of dealing with this problem are described in Supplement No. 4 [5]. + +In respect of radio-relay links, it will be the concern of CCIR to enumerate suitable precautions. + +### 4 Single tone interference + +The Recommendation cited in [6] indicates a limit for the single tone interference level in telephone circuits. Depending on the origin of such interferences, wide-band services and non-telephony services (e.g. soundprogramme circuits, etc.) may also be affected. This should be considered when defining limits for transmission systems. + +Practical experience shows that broadcasting transmitters are the main external source of single tone interference. In order to be usable under normal environmental working conditions, the carrier transmission equipment should be designed in such a way that it allows a certain electromagnetic field strength in its vicinity, caused by transmitters. A figure of 0.5 to 0.7 V/m within a station should be tolerated by equipment which is installed as normally specified and working under normal conditions. Where higher field strengths are known to be expected, suitable screening measures in the building may have to be adopted. Special attention should also be given to the stating cabling including power distribution and to the wiring of distribution racks to prevent interferences from entering the equipment via these points. + +*Note* - The Supplement No. 27 contains some information on possible measures to reduce effects from interference and on measuring methods concerning interference. + +### 5 Total interference power + +In addition to the above limitation of the single tone interference, it should be ascertained that the total interference power in each telephone channel within the band 300-3400 Hz, for each individual case of interference, should be lower than -65 dBm0. + +## References + +- [1] CCITT Recommendation *Linear crosstalk*, Vol. III, Rec. G.134. +- [2] CCITT Recommendation *General performance objectives applicable to all modern international circuits and national extension circuits*, Vol. III, Rec. G.151, § 4.1. +- [3] *Ibid.*, § 4.2. +- [4] CCITT Recommendation *Crosstalk in sound-programme circuits set up on carrier systems*, Vol. III, Rec. J. 18. +- [5] *Certain methods of avoiding the transmission of excessive noise between interconnected systems*, Green Book, Vol. III-2, Supplement No. 4, ITU, Geneva, 1973. +- [6] CCITT Recommendation *General performance objectives applicable to all modern international circuits and national extension circuits*, Vol. III, Rec. 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This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## **UNWANTED MODULATION AND PHASE JITTER** + +*(Geneva, 1972, further amended)* + +### **1 Unwanted modulation by harmonies of the power supply and other low frequencies** + +#### **1.1 Requirements on carrier transmission systems** + +To enable the limit indicated in the Recommendation cited in [1] to be met, it is recommended that a minimum side component attenuation of 45 dB should be obtained when a signal is transmitted over a channel having the same composition as the 2500 km hypothetical reference circuit for the system concerned. + +This limit is subdivided as indicated in §§ 1.2 and 1.3 below into allocations to terminal and to line equipment. + +#### **1.2 Combined effect due to all translating equipment** + +The combined effect due to all translating equipment on the hypothetical reference circuit should correspond to a minimum side component attenuation of 48 dB. + +For each translating equipment, send and receive side taken separately, and measured at the signal output, a side component attenuation of at least 63 dB should be obtained under normal operating conditions. Under adverse power supply conditions a minimum of 60 dB should be met. It is expected that then an overall value of 48 dB, indicated above, will only rarely be exceeded. + +*Note* - The above requirements are derived from the hypothetical reference circuits for the 4 MHz, 12 MHz and 60 MHz systems. The same figures may be applied to other systems provided that their hypothetical reference circuit does not differ significantly from those referred to above. + +#### **1.3 Combined effects due to all line equipment** + +The combined effects due to all line equipment on the hypothetical reference circuit should correspond to a minimum side component attenuation of 48 dB. + +Line equipments can be subject to two types of interference which will cause side components on a transmitted signal: + +- Effects from power supplies (for example, a residual mains frequency ripple may be superimposed on the d.c. power feeding current). These are potentially systematic on the complete length of the circuit. +- Effects from voltages caused by induction (for example, from railway traction currents). They are not expected to occur as systematically as the effects from the power supplies. + +The influence caused by *power supply ripple* should be such that a minimum side component attenuation of 51 dB is observed for the combined effect of all line equipment on the hypothetical reference circuit. It is recommended that on a single power feeding section, the side component attenuation should not be less than $51 + 10 \log k$ dB, where $k$ is the number of power feeding sections on the hypothetical reference circuit. + +*Note* - Based on the assumptions that some power feeding sections may be powered from battery supplies and that adverse cumulation over the full length of the hypothetical reference connection is unlikely, it can be expected that the limit of 51 dB will be observed with a high probability. + +The influence caused by *induced voltages* should be such that a minimum side component attenuation of 51 dB is observed for the combined effects of all line equipment on the hypothetical reference circuit. However, voltages caused by induction vary considerably with time. The effect of a source of induction is very often confined to one power feeding section. It seems very unlikely that the induced voltage reaches its maximum value in more than one section at the same instant. + +It is recommended that the r.m.s. value of the longitudinal voltage in a power feeding section caused by induction under normal operating conditions (excluding short circuits and arcing on railways, etc.) should not exceed 150 volts. (This limit has been recommended regarding safety aspects and is contained in [2]. It seems reasonable to adopt the same value for the present purpose.) + +Calculations indicate that an allowance of 6 dB for the combined effect of several sections under the influence of induction should cover the majority of likely cases. It is therefore recommended that a minimum side component attenuation of 57 dB should be observed on a power feeding section under the influence of the maximum allowed induced voltage. It is estimated that then the value of 51 dB on a circuit of 2500 km would only be exceeded in rare circumstances and infrequently, particularly in view of the fact that only a fraction of the total length would be exposed to interference by induction. + +### 2 Phase jitter due to translating equipments + +For each translating equipment, send and receive sides taken separately, a phase jitter on a signal should not exceed 1° peak-to-peak when measured on the output of the equipment. The measurement should be of all phase jitter components on each side of the signal in the frequency band 20-300 Hz, i.e. equivalent to the frequency band indicated in Recommendation O.91 [3]. + +*Note 1* - The above requirement is derived from a consideration of data signals on a telephone-type circuit over a 2500-km hypothetical reference circuit. Conforming to this requirement will ensure a high probability that the overall phase jitter from this source will not exceed 6° peak-to-peak. This performance will also ensure a high probability that for telephone speech transmission the phase jitter will be below the detection threshold of a majority of listeners. + +*Note 2* - In practice it is expected that phase jitter of the magnitude given above will occur only on translating equipments using high frequency carriers and that correspondingly lower phase jitter will be caused by translating equipment using lower frequency carriers. + +*Note 3* - Where the phase jitter is caused mainly by random noise a peak-to-peak/r.m.s. ratio of 10 should be assumed. + +## References + +- [1] CCITT Recommendation *General performance objectives applicable to all modern international circuits and national extension circuits*, Vol. III, Rec. G.151, § 7. +- [2] CCITT manual *Directives concerning the protection of telecommunication lines against harmful effects from electricity lines*, Chapter IV, §§ 6, 7 and 71, ITU, Geneva, 1963, 1965, 1974, 1978. +- [3] CCITT Recommendation *Essential clauses for an instrument to measure phase jitter on telephone circuits*, Vol. IV, Rec. O.91. \ No newline at end of file diff --git a/marked/G/T-REC-G.242-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.242-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..c67c4eb0d0dd9dad039a9efddac238750669d7e5 --- /dev/null +++ b/marked/G/T-REC-G.242-198811-I_PDF-E/raw.md @@ -0,0 +1,284 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' in a bold, sans-serif font. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.242** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER - TRANSMISSION SYSTEMS** --- + +**THROUGH - CONNECTION OF GROUPS, +SUPERGROUPS, ETC.** + +**ITU-T Recommendation G.242** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +1 ITU-T Recommendation G.242 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## Recommendation G.242 + +## THROUGH-CONNECTION OF GROUPS, SUPERGROUPS, ETC. + +*(amended at Geneva, 1964; further amended)* + +### 1 General considerations1) + +It may be found desirable from both the technical and the economical points of view to provide facilities at the end of certain sections such that the channels routed over one section do not all have to be extended to the next section, this being done without demodulating all the channels to voice frequency, whole batches of channels being extended to different line sections. + +At such points, which are at the ends of *the line links* concerned, the through-connection of batches of telephone channels should be possible from one line link to another. This can be achieved by means of the following two methods which, though basically different, can nevertheless be used in association at a given point for different batches of channels. In both cases arrangements are necessary to ensure that the through-connected frequency band is "clear", that is to say, as far as possible the channel vestiges on the two sides of the through-connected batch of channels should be suppressed by means of a through-connection filter. + +#### 1.1 *Through-group, supergroup, mastergroup, supermastergroup or 15-supergroup assembly* + +It is assumed that the batch of through-connected channels occupies the frequency band of a group, supergroup, mastergroup, supermastergroup or 15-supergroup assembly, or that it can be split into several such bands. Each of the groups, supergroups, mastergroups, supermastergroups or 15-supergroup assemblies is then brought into the basic frequency band and is filtered in that band by means of a through-group filter, or through-supergroup, through-mastergroup, through-supermastergroup or through-15-supergroup assembly filter. + +*Note* - The frequency band occupied by the 15-supergroup assembly No. 3 (8620 to 12 336 kHz) is within the frequency band occupied by the basic supermastergroup (8516 to 12 388 kHz). Hence, when 15-supergroup assemblies are used in the conditions specified in Recommendation G.211 (procedure 2), 15-supergroup assembly No. 3 can be through-connected by means of through-supermastergroup filters. + +#### 1.2 *Direct through-connection* + +It is also possible to through-connect a group, supergroup, mastergroup, supermastergroup or 15-supergroup assembly or a batch of them by direct line filtration without demodulation and passage via the basic frequency band. It is then necessary to have direct through-connection filters connected to the line equipment to effect the necessary separation. An example of this possibility is given in Recommendation G.333 for the 60 MHz system. + +In fixing the degree of suppression of unwanted components, it is convenient to use the following definitions: + +##### **intelligible crosstalk components** + +*F: composantes de diaphonie intelligible* + +*S: componentes de diafonía intelible* + +--- + +1) This Recommendation does not consider certain precautions necessary for the protection of various pilots and additional measuring frequencies. Such precautions are given in Recommendation G.243. + +Transferred speech currents which can introduce intelligible crosstalk into certain channels at the point considered. + +##### **unintelligible crosstalk components** + +*F: composantes de diaphonie inintelligible* + +*S: componentes de diafonía ininteligible* + +Transferred speech currents which can introduce unintelligible crosstalk into certain channels at the point considered. + +##### **possible crosstalk components** + +*F: composantes possibles de diaphonie* + +*S: componentes posibles de diafonía* + +Transferred speech currents which, at the point considered, do not intrude into the channels of other systems but which may do so elsewhere. + +##### **harmful out-of-band components** + +*F: composantes extra-bandes nuisibles* + +*S: componentes fuera de banda perjudiciales* + +Transferred currents arising from speech, or pilots, or additional measuring frequencies, and of frequencies such that they will always lie outside the useful frequency band (corresponding to speech frequencies) of the carrier systems, but which may interfere with pilots or additional measuring frequencies. + +##### **harmless out-of-band components** + +*F: composantes extra-bandes neutres* + +*S: componentes fuera de banda neutras* + +Transferred currents arising from speech or pilots which, at all translation points, have frequencies outside the useful frequency band corresponding to audio frequencies or pilot frequencies. + +The term "wanted component" is applied below in respect to speech band, to an 800-Hz signal with a power of 1 milliwatt sent to a zero relative level point, and in respect of pilots or additional measuring frequencies, to the signal of specified frequency and level at the point where it is normally injected. + +### **2 Through-group connection** + +#### **2.1 Ratio between the wanted and unwanted components** + +In the case of through-connection of a group, the ratio between the wanted components and the various unwanted components defined above should be: + +- 1) intelligible crosstalk components: 70 dB; +- 2) unintelligible crosstalk components: 70 dB; +- 3) possible crosstalk components: 35 dB wherever possible components appear; +- 4) harmful out-of-band components: 40 dB; +- 5) harmless out-of-band components: 17 dB. + +All these separations must be provided by the transfer filter itself. They relate to the nominal level, 84 kHz which is the reference frequency (close to the group pilots) at which the loss of the group transfer filter is set. At the other frequencies, account should be taken of the tolerance allowed for the distortion loss of this filter. + +At any temperature between 10 ° C and 40 ° C, insertion loss for all the through-group connection equipment2) at any frequency of the passband (60.6 to 107.7 kHz3)) should not depart from the loss at 84 kHz4) by more than ± 1 dB. + +The loss between 10 ° C and 40 ° C at 84 kHz should not differ by more than ± 1 dB from the loss at 25 ° C. + +*Note 1* - It would be technically difficult for the CCITT to recommend a distribution of these overall limits among the equipments mentioned in footnote 2 on this page. + +*Note 2* - The value of 70 dB shown in 1) and 2) above for the intelligible or unintelligible crosstalk components is the minimum standard value for telephony. A value of 80 dB is recommended in the band which, in each group adjacent to the through-connected group, corresponds to the band 84 to 96 kHz in the basic group and which may therefore be used for programme transmissions by systems, whether or not equipped with compressors having the characteristics defined in Recommendation J.31, § 1.5 [1]. + +This condition should be fulfilled both when the adjacent group is direct and when it is inverted. + +*Note 3* - As a consequence of the condition in Note 2 above, in each through-connected group, the value recommended will also be achieved in the band corresponding to the band 72 to 84 kHz in the basic group. + +*Note 4* - The values recommended above for the intelligible or unintelligible crosstalk components are also compatible with the use of 15 kHz circuits (Recommendation J.21 [2]) and 7 kHz circuits (Recommendation J.23 [3]) for programme transmission. Consideration is given to the fact that the equipments used to set up these circuits (Recommendation J.31 [1] and Annexes, Recommendation J.34 [4]) are single sideband systems with compandors or double sideband systems. Account was also taken of the frequency band occupied by the programme channels of the equipments in the basic group and of the frequency response characteristics of the weighting network referred to in Recommendation J.16 [5]. + +#### 2.2 *Group-delay distortion of the through-group filter* + +In the case of through-connection of a group in the basic frequency band 60-108 kHz, it is recommended that the limits in Figure 1/G.242 for the group-delay distortion (relative to the value at 84 kHz) should not be exceeded by the through-group filter. + +*Note* - The range of measured values on modern equipments is indicated in Supplement 17 at the end of this fascicle. + +--- + +2) This equipment comprises a group demodulation equipment, the through-group filter proper and a group modulation equipment. + +3) If 16-channel groups be used, the passband must be extended from 60.1 to 107.9 kHz or, by agreement between the Administrations concerned, the band indicated in the present recommendation must be kept, in which event Note 1 to Recommendation G.235 will have to be carefully borne in mind. + +4) Slightly different loss limits apply outside the band occupied by the telephone channels when out-of-band signalling is used; this point can be settled on the national level or by agreement between the Administrations concerned. + +![Figure 1/G.242: A graph showing Group-delay distortion (ΔT) in microseconds (μs) versus Frequency in kHz. The y-axis ranges from -20 to 220 μs, with major ticks at -20, 0, 50, 80, and 220. The x-axis ranges from 60 to 108 kHz, with major ticks at 60, 64, 68, 72, 84, 96, 100, 104, and 108 kHz. The graph shows a piecewise constant function with shaded regions indicating tolerance limits. The function is 0 μs from 60 to 64 kHz, 220 μs from 64 to 68 kHz, 80 μs from 68 to 72 kHz, 50 μs from 72 to 96 kHz, 80 μs from 96 to 100 kHz, and 220 μs from 100 to 104 kHz. Shaded regions are shown above and below the 0 μs line, and above the 220 μs line in the 64-68 kHz and 100-104 kHz bands. A small circle is marked on the 0 μs line at 84 kHz. The text 'CCITT - 32861' is in the bottom right corner.](431b8889a0e7f676f0eef40859590349_img.jpg) + +Figure 1/G.242: A graph showing Group-delay distortion (ΔT) in microseconds (μs) versus Frequency in kHz. The y-axis ranges from -20 to 220 μs, with major ticks at -20, 0, 50, 80, and 220. The x-axis ranges from 60 to 108 kHz, with major ticks at 60, 64, 68, 72, 84, 96, 100, 104, and 108 kHz. The graph shows a piecewise constant function with shaded regions indicating tolerance limits. The function is 0 μs from 60 to 64 kHz, 220 μs from 64 to 68 kHz, 80 μs from 68 to 72 kHz, 50 μs from 72 to 96 kHz, 80 μs from 96 to 100 kHz, and 220 μs from 100 to 104 kHz. Shaded regions are shown above and below the 0 μs line, and above the 220 μs line in the 64-68 kHz and 100-104 kHz bands. A small circle is marked on the 0 μs line at 84 kHz. The text 'CCITT - 32861' is in the bottom right corner. + +FIGURE 1/G.242 + +### 3 Through-supergroup connection + +#### 3.1 Ratio between the wanted and unwanted components + +In the case of through-connection of a supergroup, the ratio between the wanted components and the various unwanted components defined above should be: + +- | | | +|-----------------------------------------|--------------------------------------------| +| 1) intelligible crosstalk components: | 70 dB; | +| 2) unintelligible crosstalk components: | 70 dB; | +| 3) possible crosstalk components: | 35 dB wherever possible components appear; | +| 4) harmful out-of-band components: | 40 dB 5) ; | +| 5) harmless out-of-band components: | 17 dB. | + +5) The specified attenuation should be met at the nominal frequencies of the pilots and additional measuring frequencies involved (at a point where these are 308 kHz or 556 kHz) in accordance with the definition of harmful out-of-band components. + +All these separations must be provided by the through-supergroup filter itself. They relate to the nominal level 412 kHz, which is the reference frequency (close to the supergroup pilots), at which the loss of the supergroup transfer filter is set. At the other frequencies, account should be taken of the tolerance allowed for the distortion loss of this filter. + +At any temperature between 10 ° C and 40 ° C, insertion loss for all the through-supergroup connection equipment6) at any frequency of the passband (312.3 to 551.4 kHz) should not depart from the loss at 412 kHz7) by more than $\pm 1$ dB. + +The loss between 10 ° C and 40 ° C at 412 kHz should not differ by more than $\pm 1$ dB from the loss at 25 ° C. + +*Note 1* - It would be technically difficult for the CCITT to recommend a distribution of these overall limits among the equipments mentioned in footnote 6 above. + +*Note 2* - The ratio of 70 dB shown in 1) and 2) above for the intelligible or unintelligible crosstalk components is a minimum standard value for telephony. A separation of 80 dB is advocated for the bands liable to be used for programme transmission in each supergroup adjacent to the transferred supergroup. + +*Note 3* - In the case of through-connection of supergroup 1 or 3, the range of insertion loss of the combined through-supergroup equipment can reach 3 dB in the passband of the filter around 312 kHz or 552 kHz. + +#### 3.2 Group-delay distortion of the through-supergroup filter + +In the case of through-connection of a supergroup in the basic frequency band 312-552 kHz, it is recommended that the limits in Figure 2/G.242 for the group-delay distortion (relative to the value at 412 kHz) should not be exceeded by the through-supergroup filter. + +*Note* - The range of measured values on modern equipments is indicated in Supplement 17 at the end of this fascicle. + +![Figure 2/G.242: A graph showing Group-delay distortion (ΔT) in microseconds (μs) versus Frequency in kHz. The y-axis ranges from -5 to 25 μs, with major ticks at -5, 0, 12, and 25. The x-axis ranges from 312 to 552 kHz, with major ticks at 312, 352, 364, 412, 500, 512, and 552. A reference point is marked at 412 kHz on the x-axis. The graph shows a shaded region representing the allowed distortion limits. The upper limit is 25 μs from 352 kHz to 364 kHz, then drops to 12 μs from 364 kHz to 500 kHz, and rises back to 25 μs from 500 kHz to 512 kHz. The lower limit is -5 μs from 352 kHz to 512 kHz. The region between 352-364 kHz and 500-512 kHz is shaded with diagonal lines, while the region between 364-500 kHz is shaded with horizontal lines.](797231cfee084ca299de599340240401_img.jpg) + +Figure 2/G.242: A graph showing Group-delay distortion (ΔT) in microseconds (μs) versus Frequency in kHz. The y-axis ranges from -5 to 25 μs, with major ticks at -5, 0, 12, and 25. The x-axis ranges from 312 to 552 kHz, with major ticks at 312, 352, 364, 412, 500, 512, and 552. A reference point is marked at 412 kHz on the x-axis. The graph shows a shaded region representing the allowed distortion limits. The upper limit is 25 μs from 352 kHz to 364 kHz, then drops to 12 μs from 364 kHz to 500 kHz, and rises back to 25 μs from 500 kHz to 512 kHz. The lower limit is -5 μs from 352 kHz to 512 kHz. The region between 352-364 kHz and 500-512 kHz is shaded with diagonal lines, while the region between 364-500 kHz is shaded with horizontal lines. + +FIGURE 2/G.242 + +6) This equipment comprises a supergroup demodulation equipment, the through-supergroup filter proper and a supergroup modulation equipment. + +7) Slightly different loss limits apply outside the band occupied by the telephone channels when out-of-band signalling is used; this point can be settled on the national level or by agreement between the Administrations concerned. + +### 4 Through-mastergroup connection + +For the through-mastergroup connection, the ratio between wanted components and the various unwanted components defined above should be: + +- 1) intelligible crosstalk components: 70 dB; +- 2) unintelligible crosstalk components: 70 dB; +- 3) possible crosstalk components: 35 dB wherever possible components appear; +- 4) harmful out-of-band components: 40 dB8); +- 5) harmless out-of-band components: 17 dB. + +All these ratios should be achieved by the through-mastergroup filter itself. They refer to the nominal level of the 1552-kHz reference frequency (mastergroup pilot) by which the loss of the through-mastergroup filter is fixed. At other frequencies, the attenuation/frequency distortion tolerance allowed for this filter should be taken into consideration. + +At any temperature between 10 °C and 40 °C, the loss at any frequency within the passband (812 to 2044 kHz) of the combined through-mastergroup equipment9) should not deviate by more than $\pm 1$ dB from the loss at 1552 kHz. + +The loss between 10 °C and 40 °C, at 1552 kHz, should not deviate by more than $\pm 1$ dB from the loss at 25 °C. + +Within each supergroup the total variation of the insertion loss should not exceed $\pm 1$ dB relative to the loss at the frequency of the supergroup reference pilot. + +*Note* - The ratio of 70 dB shown in 1) and 2) above for intelligible or unintelligible crosstalk components is a minimum standard value for telephony. A separation of 80 dB is advocated for the bands liable to be used for programme transmission in each mastergroup adjacent to the transferred mastergroup. + +### 5 Through-supermastergroup connection + +For the through-supermastergroup connection, the ratio between wanted components and the various unwanted components defined above should be: + +- 1) intelligible crosstalk components: 70 dB; +- 2) unintelligible crosstalk components: 70 dB; +- 3) possible crosstalk components: 35 dB; wherever possible components appear; +- 4) harmful out-of-band components: 40 dB10); +- 5) harmless out-of-band components: 17 dB. + +All these ratios should be achieved by the through-supermastergroup filter itself. They refer to the nominal level of the 11 096 kHz reference frequency (supermastergroup pilot) by which the loss of the combined supermastergroup equipment11) is fixed. At other frequencies the attenuation/frequency distortion tolerance allowed for this filter should be taken into consideration. + +--- + +8) The specified attenuation should be met over a band corresponding to the recommended frequency stability of the original frequencies of the pilots or the additional measuring frequencies involved (where these are translated to 768 kHz or 2088 kHz) in accordance with the definition of harmful out-of-band components. + +9) This equipment comprises a mastergroup demodulation equipment, the through-mastergroup filter proper, and a mastergroup translating equipment. + +10) The specified attenuation should be met over a band corresponding to the recommended frequency stability of the original frequencies of the pilots or the additional measuring frequencies involved (after frequency translation of the supermastergroup into the basic 8516-12 388 kHz band) in accordance with the definition of harmful out-of-band components. + +11) This equipment comprises the supermastergroup demodulation equipment, the through-supermastergroup filter proper and supermastergroup translating equipment. + +At any temperature between 10 ° C and 40 ° C, the insertion loss at any frequency within the passband 8516 to 12 388 kHz of the combined through-supermastergroup equipment should not deviate by more than $\pm 1.5$ dB from the loss at 11 096 kHz. Within each mastergroup the total variation in insertion loss should not exceed $\pm 1$ dB relative to the loss at the frequency of the mastergroup pilot. + +The loss between 10 ° C and 40 ° C, at 11 096 kHz, should not deviate by more than $\pm 1$ dB from the loss at 25 ° C. + +*Note* - The ratio of 70 dB shown in 1) and 2) above for intelligible or unintelligible crosstalk components is a minimum standard value for telephony. A separation of 80 dB is advocated for the bands liable to be used for programme transmission in each supermastergroup adjacent to the transferred supermastergroup. + +### 6 Through-15-supergroup assembly connection + +For through-15-supergroup assembly (No. 1) connection, the ratio between wanted components and the various unwanted components defined above should be: + +- 1) intelligible crosstalk components: 70 dB; +- 2) unintelligible crosstalk components: 70 dB; +- 3) possible crosstalk components: 35 dB wherever possible components appear; +- 4) harmful out-of-band components: 40 dB12); +- 5) harmless out-of-band components: 17 dB. + +All these ratios should be achieved by the through-15-supergroup filter itself. They refer to the nominal level of the 1552-kHz reference frequency (frequency of the basic 15-supergroup assembly pilot) by which the loss of the through basic 15-supergroup assembly No. 1 filter is fixed. At other frequencies, the attenuation/frequency distortion tolerance allowed for the filter should be taken into consideration. + +Alternatively, the above ratios may be provided by a through-connection equipment13) that incorporates the necessary filtering within the 15-supergroup assembly demodulator and the 15-supergroup assembly modulator. + +At any temperature between 10 ° C and 40 ° C, the loss at any frequency within the passband (312 to 4028 kHz) of the combined through-15-supergroup equipment13) should not deviate by more than $\pm 1.5$ dB from the loss at 1552 kHz. + +The loss between 10 ° C and 40 ° C at 1552 kHz should not deviate by more than $\pm 1$ dB from the loss at 25 ° C. + +Within each supergroup, the total variation of the insertion loss should not exceed $\pm 1$ dB relative to the loss at the frequency of the supergroup reference pilot. + +*Note* - The ratio of 70 dB shown in 1) and 2) above for intelligible or unintelligible crosstalk components is a minimum standard value for telephony. A separation of 80 dB is advocated for the bands liable to be used for programme transmission in each 15-supergroup assembly adjacent to the transferred 15-supergroup assembly. + +### 7 Direct through-connection + +The values recommended for the attenuation of the various crosstalk components are the same as those given in §§ 2 to 6 above for through-connection of groups, supergroups, etc., in as far as they are not in contradiction with those recommended in Recommendation G.243, § 5. + +--- + +12) The specified attenuation should be met over a band corresponding to the recommended frequency stability of the original frequencies of the pilots or the additional frequencies involved (after frequency translation of the 15-supergroup assembly into the basic 312-4028 kHz band) in accordance with the definition of harmful out-of-band components. + +13) This equipment comprises the 15-supergroup assembly demodulation equipment, the through-connection filter (if any) and the 15-supergroup assembly-translating equipment. + +## References + +- [1] CCITT Recommendation *Characteristics of equipment and lines used for setting up 15 kHz type sound-programme circuits*, Vol. III, Rec. J.31. +- [2] CCITT Recommendation *Performance characteristics of 15 kHz type sound-programme circuits*, Vol. III, Rec. J.21. +- [3] CCITT Recommendation *Performance characteristics of narrow-bandwidth sound-programme circuits*, Vol. III, Rec. J.23. +- [4] CCITT Recommendation *Characteristics of equipment used for setting up 7 kHz type sound-programme circuits*, Vol. III, Rec. J.34. +- [5] CCITT Recommendation *Measurement of weighted noise in sound-programme circuits*, Vol. III, Rec. J.16. \ No newline at end of file diff --git a/marked/G/T-REC-G.322-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.322-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..19768f4e722015715ee33261625d3d7548dfd5fa --- /dev/null +++ b/marked/G/T-REC-G.322-198811-I_PDF-E/raw.md @@ -0,0 +1,423 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.322** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES** --- + +## **GENERAL CHARACTERISTICS RECOMMENDED FOR SYSTEMS ON SYMMETRIC PAIR CABLES** + +**ITU-T Recommendation G.322** + +(Extract from the *Blue Book*) + +--- + +### NOTES + +1 ITU-T Recommendation G.322 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +###### Recommendation G.322 + +## GENERAL CHARACTERISTICS RECOMMENDED FOR SYSTEMS ON SYMMETRIC PAIR CABLES + +This Recommendation applies to systems using types of cable so far recommended by the CCITT (see Recommendation G.611) and providing 1, 2, 3, 4 or 5 groups or 2 supergroups. + +## 1 General recommendations + +### 1.1 Hypothetical reference circuits + +1.1.1 The hypothetical reference circuit on symmetric pairs is 2500 km long, and is set up on a symmetric pair carrier system. For each direction of transmission, it has a total of: + +- three pairs of channel modulators and demodulators, +- six pairs of group modulators and demodulators, +- six pairs of supergroup modulators and demodulators1). + +Figure 1/G.322 shows a diagram of the hypothetical reference circuit on symmetric pairs. It will be seen that there is a total of 15 modulations and 15 demodulations for each direction of transmission supposing that each modulation or demodulation is effected by a single stage1). + +![Diagram of the hypothetical reference circuit on symmetric cable pairs. The diagram shows a 2500 km long circuit composed of six homogeneous sections. Each section contains a series of modulators and demodulators. The first section is labeled 'Line-frequency band', the second 'Audio-frequency band', and the third 'Basic group frequency band'. The diagram is labeled 'CCITT - 45480' at the bottom right.](b612b838f94982799a69461ffb078a73_img.jpg) + +The diagram illustrates a 2500 km long hypothetical reference circuit on symmetric cable pairs. It is divided into six homogeneous sections of equal length. Each section contains a series of modulators and demodulators. The first section is labeled 'Line-frequency band', the second 'Audio-frequency band', and the third 'Basic group frequency band'. The diagram is labeled 'CCITT - 45480' at the bottom right. + +Diagram of the hypothetical reference circuit on symmetric cable pairs. The diagram shows a 2500 km long circuit composed of six homogeneous sections. Each section contains a series of modulators and demodulators. The first section is labeled 'Line-frequency band', the second 'Audio-frequency band', and the third 'Basic group frequency band'. The diagram is labeled 'CCITT - 45480' at the bottom right. + +FIGURE 1/G.322 + +##### Diagram of the hypothetical reference circuit on symmetric cable pairs + +This hypothetical reference circuit consists of 6 homogeneous sections of equal length (see Recommendation G.212). + +The number of pairs in the cable is assumed to be the same in all sections. + +The hypothetical reference circuit on symmetric pairs thus defined is used for systems providing 1, 2, 3, 4 or 5 groups. + +1) Where systems provide 1, 2, 3 or 4 groups, it is possible to have a smaller number of modulations, but this does not detract from the usefulness of the idea of a hypothetical reference circuit on symmetric pairs. + +1.1.2 The composition of the hypothetical reference circuit for a 10-group (2-supergroup) carrier system should be the same as that of the hypothetical reference circuit for a 16-supergroup coaxial cable system (see [1]). + +### 1.2 *Design objectives for circuit noise* + +The objectives mentioned in Recommendation G.222 are applicable to hypothetical reference circuits in the circumstances indicated in Recommendation G.223. + +In practice, it is sufficient to check by calculation that, for every telephone channel as defined by the hypothetical reference circuit on symmetric pairs, the mean psophometric power at the end of the channel referred to a point of zero relative level does not exceed 10 000 pW0p during any period of one hour. + +The subdivision of the total noise between: + +- basic noise, +- intermodulation noise, +- noise due to crosstalk, + +is left entirely to the designer of the system, within the limits of 2500 pW0p for the terminal equipment and 7500 pW0p for the line. + +*Note* - In planning a carrier system on symmetric pairs, calculation of the noise due to crosstalk could be carried out by the methods described in [2], [3] and [4]. + +### 1.3 *Line-frequency spectrum* + +##### 1.3.1 *Systems providing 1, 2 or 3 groups* + +The line-frequency spectrum should be in accordance with the scheme shown in Figure 2 a)/G.322. + +##### 1.3.2 *Systems providing 4 groups* + +The frequency spectrum transmitted to line should be in accordance with Scheme 1 of Figure 2 b)/G.322. + +*Note* - By agreement between the Administrations concerned, it is possible to omit one group of supergroup 1\* shown in Scheme 2 of Figure 2 c)/G.322, for systems with five groups; if this is done, Scheme 1 *bis* of Figure 2 b)/G.322, is obtained. + +##### 1.3.3 *Systems providing 5 groups* + +The frequency spectrum transmitted to line should be in accordance with Scheme 2 of Figure 2 c)/G.322. + +*Note 1* - Where there is direct interconnection between a system with 5 groups on symmetric pairs and systems with a smaller number of groups, by agreement between the Administrations concerned, the system with 5 groups, shown in Scheme 2 *bis* of Figure 2 c)/G.322, may be used. + +*Note 2* - By agreement between the Administrations concerned, the arrangement in Figure 3/G.322 can be used for a supergroup on a coaxial cable system which is to be interconnected at basic supergroup frequencies (312-552 kHz) with either a 5-group system on symmetric pairs using Scheme 2 *bis* [Figure 2 c)/G.322], or with a 4-group system using Scheme 1 [Figure 2 b)/G.322]. + +Supplement No. 8 [5] shows a simple way of assembling basic groups B into a supergroup in accordance with one of the schemes shown in Figure 3/G.322 and in Figure 1/G.338 [6] and vice versa. + +##### 1.3.4 *Systems providing 2 supergroups* + +The frequency spectrum transmitted to line should be in accordance with either Scheme 3 or Scheme 4 of Figure 4/G.322, whichever the Administration decides. + +Supergroups 1 and 2 are the same as those in coaxial cable carrier systems. Supergroup 1\* is the same as that normally recommended for 5-group systems on symmetric cable pairs. + +*Note* - By agreement between the Administrations concerned, for five group systems on symmetric cable pairs, instead of supergroup 1\*, supergroup 1\*' may be used [Scheme 2 bis, Figure 2 c)/G.322], which gives the arrangement shown in Scheme 3 bis of Figure 4/G.322. + +### 1.4 Line-regulating pilots + +##### 1.4.1 Systems providing 1, 2, 3, 4 or 5 groups + +Either of the following methods can be used (see Figure 5/G.322). + +Either of these methods can be chosen by the Administrations concerned and can be used without difficulty, provided the pilots are efficiently suppressed at the end of a regulated-line section. + +![Figure 2/G.322: Line-frequency allocation for international carrier systems on symmetric cable pairs. The figure shows three sub-diagrams (a, b, c) illustrating different group and supergroup configurations. Each diagram plots Group/Supergroup labels and Channel Numbers against frequency in kHz. Schemes 1 and 2 are recommended, while Schemes 1 bis and 2 bis are optional by agreement.](0ad3f61f997eb05afb341fc46024bf2b_img.jpg) + +**Group** +**Channel No.** + +**A B C** + +12 60 108 156 kHz + +1...12 12...1 12...1 + +a) Systems providing one, two or three groups + +**Group** +**Channel No.** + +**A B C D** + +12 60 108 156 204 kHz + +1...12 12...1 12...1 12...1 + +**Scheme 1 (recommended)** + +**Supergroup** + +1\* + +**Group** +**Channel No.** + +**5 4 3 2** + +12 60 108 156 204 kHz + +12...1 12...1 12...1 12...1 + +**Scheme 1 bis (which may be used by agreement between Administrations)** + +b) Systems providing four groups + +**Supergroup** + +1\* + +**Group** +**Channel No.** + +**5 4 3 2 1** + +12 60 108 156 204 252 kHz + +12...1 12...1 12...1 12...1 12...1 + +**Scheme 2 (recommended)** + +**Supergroup** + +1\*' + +**Group** +**Channel No.** + +**A B C D E** + +12 60 108 156 204 252 kHz + +1...12 12...1 12...1 12...1 12...1 + +**Scheme 2 bis (which may be used by agreement between Administrations)** + +CCITT - 38790 + +c) Systems providing five groups + +Figure 2/G.322: Line-frequency allocation for international carrier systems on symmetric cable pairs. The figure shows three sub-diagrams (a, b, c) illustrating different group and supergroup configurations. Each diagram plots Group/Supergroup labels and Channel Numbers against frequency in kHz. Schemes 1 and 2 are recommended, while Schemes 1 bis and 2 bis are optional by agreement. + +FIGURE 2/G.322 + +Line-frequency allocation for international carrier systems on symmetric cable pairs + +![Diagram showing the internal structure of a supergroup. It is divided into five groups (A, B, C, D, E) and 12 channels. The frequency range is from 554 kHz to 804 kHz. The diagram shows the relative positions of groups and channels within supergroup 3'.](4086a572c080354982c11f1de4d6921d_img.jpg) + +Supergroup 3' + +Group: A, B, C, D, E + +Channel No.: 1, 12, 12, 1, 12, 1, 12, 1, 12, 1 + +554 612 660 708 756 804 kHz + +Diagram showing the internal structure of a supergroup. It is divided into five groups (A, B, C, D, E) and 12 channels. The frequency range is from 554 kHz to 804 kHz. The diagram shows the relative positions of groups and channels within supergroup 3'. + +a) Arrangement of groups and channels (supergroup 3' has been shown as an example) + +![Two diagrams showing the arrangement of groups and channels in a supergroup. The top diagram shows supergroups 1, 2, 3', and 4. The bottom diagram shows supergroups 1, 2', 3, and 4. Frequency markers are provided at 60, 300, 312, 552, 564, 804, 812, and 1052 kHz.](c0843c6d138705289960d9f53a6e72a1_img.jpg) + +Supergroup: 1, 2, 3', 4 + +Group: 5, 4, 3, 2, 1 | 1, 2, 3, 4, 5 | A, B, C, D, E | 5, 4, 3, 2, 1 + +60 300 312 552 564 804 812 1052 kHz + +Supergroup: 1, 2', 3, 4 + +Group: 5, 4, 3, 2, 1 | E, D, C, B, A | 5, 4, 3, 2, 1 | 5, 4, 3, 2, 1 + +60 300 312 552 564 804 812 1052 kHz + +CCITT - 45500 + +Two diagrams showing the arrangement of groups and channels in a supergroup. The top diagram shows supergroups 1, 2, 3', and 4. The bottom diagram shows supergroups 1, 2', 3, and 4. Frequency markers are provided at 60, 300, 312, 552, 564, 804, 812, and 1052 kHz. + +b) Example of possible positions, in the coaxial line-frequency band of the supergroup corresponding to Scheme 2 bis of Figure 2c)/G.322 + +FIGURE 3/G.322 + +Arrangement of groups in a supergroup, which may be used in coaxial carrier systems interconnected with systems on symmetric pairs + +![Three diagrams showing different schemes for arranging groups in a supergroup. Scheme 3 (recommended) uses groups 1-5 and 1-5. Scheme 3 bis (may be used by agreement) uses groups A-E and 1-5. Scheme 4 (recommended) uses groups 1-5 and 1-5. Frequency markers are provided at 12, 60, 108, 156, 204, 252, 312, 360, 408, 456, 504, 552, and 556 kHz.](01da0d212fb571933f10f96556157745_img.jpg) + +Supergroup: 1\*, 2 + +Group: 5, 4, 3, 2, 1 | 1, 2, 3, 4, 5 + +12 60 108 156 204 252 312 360 408 456 504 552 556 kHz + +Scheme 3 (recommended) + +Supergroup: 1\*', 2 + +Group: A, B, C, D, E | 1, 2, 3, 4, 5 + +12 60 108 156 204 252 312 360 408 456 504 552 556 kHz + +Scheme 3 bis (may be used by agreement between Administrations) + +Supergroup: 1, 2 + +Group: 5, 4, 3, 2, 1 | 1, 2, 3, 4, 5 + +60 108 156 204 252 300 312 360 408 456 504 552 556 kHz + +Scheme 4 (recommended) + +CCITT - 38800 + +Three diagrams showing different schemes for arranging groups in a supergroup. Scheme 3 (recommended) uses groups 1-5 and 1-5. Scheme 3 bis (may be used by agreement) uses groups A-E and 1-5. Scheme 4 (recommended) uses groups 1-5 and 1-5. Frequency markers are provided at 12, 60, 108, 156, 204, 252, 312, 360, 408, 456, 504, 552, and 556 kHz. + +FIGURE 4/G.322 + +Line-frequency allocation for international carrier systems providing 2 supergroups on symmetric pair cables + +![Figure 5/G.322: Line-regulating pilots for carrier systems on symmetric pairs. The figure shows two variants, A and B, for 1-group, 2-group, 3-group, 4-group, and 5-group systems. Variant A shows a single pilot at 60 kHz for 1-group systems, and additional pilots at 112, 160, 208, and 256 kHz for 2, 3, 4, and 5-group systems respectively. Variant B shows two pilots at 16 and 56 kHz for 1-group systems, and additional pilots at 104, 152, 200, and 248 kHz for 2, 3, 4, and 5-group systems respectively. The power level for all pilots is -15 dBm0. The frequency axis is in kHz, ranging from 12 to 252. A note indicates that the group shown dotted can be inverted without changing the frequencies recommended for pilots. CCITT - 45510 is noted at the bottom right.](c3c305cefbac2e7b13be34ab87054d1e_img.jpg) + +Figure 5/G.322: Line-regulating pilots for carrier systems on symmetric pairs. The figure shows two variants, A and B, for 1-group, 2-group, 3-group, 4-group, and 5-group systems. Variant A shows a single pilot at 60 kHz for 1-group systems, and additional pilots at 112, 160, 208, and 256 kHz for 2, 3, 4, and 5-group systems respectively. Variant B shows two pilots at 16 and 56 kHz for 1-group systems, and additional pilots at 104, 152, 200, and 248 kHz for 2, 3, 4, and 5-group systems respectively. The power level for all pilots is -15 dBm0. The frequency axis is in kHz, ranging from 12 to 252. A note indicates that the group shown dotted can be inverted without changing the frequencies recommended for pilots. CCITT - 45510 is noted at the bottom right. + +a) Recommended frequency; there are systems using 253 kHz. + +*Note* – The group shown dotted + +Image: dotted line with arrow + + can be inverted without changing the frequencies recommended for pilots. + +FIGURE 5/G.322 + +##### **Line-regulating pilots for carrier systems on symmetric pairs** + +###### *Method A* + +- 1) A pilot at 60 kHz with a power level of -15 dBm0, this frequency being in the gap between groups A and B and it being understood that this pilot would be used for regulation of the line on all regulated-line sections, whatever their length, and also for synchronization or checking of frequencies. +- 2) Where necessary, and especially for long regulated-line sections, an additional line-regulating pilot 4 kHz above the maximum frequency transmitted to line and with a power level of -15 dBm0. + +*Note* - There are in existence systems with five groups in which this pilot is only 1 kHz above the maximum frequency transmitted. + +The recommendation under § 2) above does not apply to systems with a single group. + +The recommended accuracy for these pilot frequencies is: + +± 1 Hz for the 60-kHz pilot; + +± 3 Hz for auxiliary pilot located 4 kHz above the maximum frequency of the channel group concerned. + +###### *Method B* + +Two pilots situated in the basic group B at 64 kHz and at 104 kHz transmitted with a power level of -17 dBm0. + +On the high-frequency line, it is possible to have two pilots per 48 kHz of transmitted band and, from amongst these pilots, 16 kHz and the maximum transmitted frequency less 4 kHz are selected. + +For systems having two or more groups, a third line-pilot is used, located between the top and bottom pilots, 64 kHz is the frequency used in 2-group systems, and 112 kHz in 5-group systems. + +Note - Method B is hardly compatible with the use of a supergroup pilot and/or the alternative group pilot 104.08 kHz (Table 4/G.232 and Recommendation G.233, § 9). + +##### 1.4.2 *System providing 2 supergroups* + +The following frequencies and levels are recommended (as shown in Method A of § 1.4.1 above): + +- lower pilot: 60 kHz power level of -15 dBm0; +- upper pilot: 4 kHz above the highest transmitted frequency, i.e. at 556 kHz, power level of -15 dBm0. + +The recommended accuracy for the frequencies of these pilots is as follows: + +± 1 Hz for the 60-kHz pilot; + +± 3 Hz for the 556-kHz pilot. + +*Note* - If a supergroup is through-connected from a coaxial-pair system to occupy the position of the upper supergroup in the band of line frequencies, there can be a residue from a line-regulating pilot or additional measuring frequency. The recommendations for the through-supergroup equipment (Recommendation G.243) ensure that this residue will be sufficiently attenuated to cause no interference with the line-regulating pilots or additional measuring frequencies of another coaxial-pair system when these are sent at a power level of -10 dBm0. So that there will be no interference with the 120-circuit system line-regulating pilot sent at -15 dBm0, this system should incorporate its own additional protection of 5 dB at 556 kHz for a through-connected supergroup. + +### 1.5 *Matching of repeater and line impedances* + +It is desirable to limit the return-current coefficient at the ends of an elementary cable section so that the effect of the reflected near-end crosstalk does not contribute excessively to the total far-end crosstalk. + +For example, in a cable which has a near-end crosstalk ratio of 56.5 dB and which meets the limit for far-end crosstalk ratio (direct far-end crosstalk) of at least 69.5 dB (the cable being between impedances equal to its characteristic impedance), the contribution of the reflected near-end crosstalk would be insignificant compared with the effect of the far-end crosstalk at the maximum frequency transmitted, if the return current coefficients between repeaters and line have the following values. + +The modulus of the return-current coefficient between the input (or output) impedance of the repeater (in its normal operating condition and including line transformers and equalizers) measured between the line terminals at the frequency $f$ , and the nominal value of the impedance at the frequency $f$ of the cable pair connected to the input (or output) of the repeater, should not exceed the value given by the formulae: + +$$0.15 \sqrt{\frac{f_{max}}{f}} \text{ or } 0.25 \text{ for systems with 1, 2 and 3 groups;}$$ + +$$0.08 \sqrt{\frac{f_{max}}{f}} \text{ or } 0.10 \text{ for systems with 4 and 5 groups or systems with 2 supergroups on paper-insulated cables (types II and III in Recommendation G.611);}$$ + +$$0.10 \sqrt{\frac{f_{max}}{f}} \text{ or } 0.17 \text{ for systems with 5 groups or systems with 2 supergroups on polythene or styroflex-insulated cables (types II bis and III bis in Recommendation G.611).}$$ + +*Note* - The values of the return-current coefficient recommended for systems with 1, 2 or 3 groups would in general be unsatisfactory if they were tolerated on all the sections of a line link; but they have been accepted as limits for a frontier section because, first, an international circuit will usually comprise only one such frontier interconnection and, second, the matching conditions at such a point may be complicated by the fact that one of the repeaters of this section may not have been specified for the exact type of cable to which it is connected. + +## 2 Special recommendations (formerly Part B) + +### 2.1 Systems to be used simultaneously with valve-type systems in the same cables + +In those exceptional cases when some pairs in an elementary cable section are already equipped with valve-type systems and it is desired to equip the free pairs with new transistor systems without changing the existing installations, the new system using transistors must meet the recommendations in § 1 above and also the provisions of Recommendation G.324 [7] relating to valve-type systems. However, it may depart from those Recommendations specifying permissible values for amplifier harmonic margin and overload point [8]. + +*Note* - Recommendation G.323 gives an example of a 60-channel high-gain transistor system. + +### 2.2 Low-gain systems + +##### 2.2.1 Relative level at the output of the repeaters + +The relative level per channel, at any frequency, at the output of each repeater shall be: + +- 11 dBr for systems with 1, 2 or 3 groups; +- 14 dBr for systems with 4 or 5 groups or 2 supergroups. + +##### 2.2.2 Monitoring frequencies + +If a monitoring (or fault-locating) frequency is sent over a normally operating system, it may for example be in the band 560-600 kHz for a 2-supergroup system. + +*Note* - Frequencies sent only over a system already withdrawn from service because of a fault can be selected by each Administration on the national level. + +##### 2.2.3 Harmonic distortion + +The harmonic distortion of a repeater should not exceed a value corresponding to the limits shown in the Table I/G.322. + +TABLE I/G.322 + +| Limits for | Systems providing | | | +|-----------------------------------------|-------------------|---------------|---------------| +| | 1, 2 or 3 groups | 4 or 5 groups | 2 supergroups | +| 2nd-order harmonic margin a) | 79 dB | 82 dB | 85 dB | +| 3rd-order harmonic margin a) | 92 dB | 98 dB | 104 dB | + +a) For definition, see Reference [9]. + +*Note* - These values are measured for a power of 1 mW applied at a point of zero relative level on any channel. + +##### 2.2.4 Noise factor + +The noise factor of a complete repeater (taking into account noise due to the transistors, the input network and the line-matching network) must not exceed 10 dB. + +##### 2.2.5 *Overload point* + +The overload point, defined in § 6.1 of Recommendation G.223, must be at least 14 dBm for the intermediate repeaters. + +*Note* - For determination of this overload point, account has been taken of a margin of a few decibels for level variations due to geographical differences with respect to the theoretical site of a repeater, to temperature variations of the cable, to equalization inaccuracies, etc. In stations where this margin is unnecessary, a repeater overload point that is slightly lower may therefore be chosen. + +##### 2.2.6 *Crosstalk ratio between repeaters in the same station* + +A typical figure for the crosstalk ratio between repeaters in the same station is 87 dB. With this figure it is possible to use repeater stations regardless of the cable-balancing method adopted. + +*Note* - If, however, the cable is balanced by elementary sections in the conventional way, a figure of 80 dB is adequate. + +The figures given above apply to all the equipment at the repeater station, from the input transformer to the output transformer. + +##### 2.2.7 *Power feeding* + +In the absence of a special agreement between the Administrations concerned in a power-feeding section crossing a frontier, it is recommended that each Administration power-feed only the repeater stations on its own territory. + +## References + +- [1] CCITT Recommendation *4-MHz valve-type systems on standardized 2.6/9.5-mm coaxial cable pairs*, Orange Book, Vol. III-1, Rec. G.338, c), ITU, Geneva, 1977. +- [2] *Method of use by the French Administration of the hypothetical reference circuit for carrier systems on symmetric pairs*, CCITT Blue Book, Vol. III, Part 4, Annex 14, ITU, Geneva, 1965. +- [3] *Contribution by the Federal German Administration to the study of noise on carrier systems worked over symmetric pairs*, CCITT Blue Book, Vol. III, Part 4, Annex 15, ITU, Geneva, 1965. +- [4] *Calculation of crosstalk noise on symmetric pair systems*, CCITT Blue Book, Vol. III, Part 4, Annex 16, ITU, Geneva, 1965. +- [5] *Method proposed by the Belgian Telephone Administration for interconnection between coaxial and symmetric pair systems*, Green Book, Vol. III-2, Supplement No. 8, ITU, Geneva, 1973. +- [6] CCITT Recommendation *4-MHz valve-type systems on standardized 2.6/9.5-mm coaxial cable pairs*, Orange Book, Vol. III-1, Rec. G.338, Figure 1/G.338, ITU, Geneva, 1977. +- [7] CCITT Recommendation *General characteristics for valve-type systems on symmetric cable pairs*, Orange Book, Vol. III-1, Rec. G.324, ITU, Geneva, 1977. +- [8] *Ibid.*, B.c) and B.d). +- [9] CCITT Definition: *$n^{\text{th}}$ order harmonic distortion*, Vol. X (Terms and Definitions). \ No newline at end of file diff --git a/marked/G/T-REC-G.325-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.325-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..e7770f66c6c649db88cedc4e76e8a26f7e2aba18 --- /dev/null +++ b/marked/G/T-REC-G.325-198811-I_PDF-E/raw.md @@ -0,0 +1,178 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.325** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES** --- + +### **GENERAL CHARACTERISTICS RECOMMENDED FOR SYSTEMS PROVIDING 12 TELEPHONE CARRIER CIRCUITS ON A SYMMETRIC CABLE PAIR [12 + 12) SYSTEMS]** + +**ITU-T Recommendation G.325** + +(Extract from the *Blue Book*) + +--- + +### NOTES + +1 ITU-T Recommendation G.325 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +#### Recommendation G.325 + +### GENERAL CHARACTERISTICS RECOMMENDED FOR SYSTEMS PROVIDING 12 TELEPHONE CARRIER CIRCUITS ON A SYMMETRIC CABLE PAIR [(12 + 12) SYSTEMS] + +Systems of the (12 + 12) type on symmetric pair in cable are used for carrier working either on old deloaded cables or on cables specially constructed for the purpose (without a second cable being required). These systems may be used in regional or local relations, or in long-distance relations, trunk or international. + +This Recommendation applies to systems for long-distance relations making use of the kinds of cable at present recommended by the CCITT (see Recommendation G.611) and to multiple-twin quad cables with conductors of 0.9 mm diameter, with an effective capacitance of 35 to 40 nF/km or other kinds of deloaded cables of equivalent quality. For systems used for local or regional relations, some clauses of the present Recommendation may be made less stringent. + +#### 1 Frequency spectrum transmitted to line + +The CCITT recommends that the line-frequency spectrum should be in accordance with Scheme 1 or 2 of Figure 1/G.325. + +![Figure 1/G.325: Arrangement of line-transmitted frequencies for international (12 + 12) cable systems. The figure shows two frequency schemes. Scheme 1 has a frequency range from 12 kHz to 120 kHz, with 12 channels numbered 1 to 12. Pilot frequencies are indicated at 60 kHz and 72 kHz. Scheme 2 has a frequency range from 6 kHz to 108 kHz, also with 12 channels numbered 1 to 12. Pilot frequencies are indicated at 54 kHz and 60 kHz. Both schemes show a triangular envelope for the channel frequencies. The text 'CCITT - 45520' is present near Scheme 2.](9455ca65b9fc488df790769b0122628e_img.jpg) + +Figure 1/G.325: Arrangement of line-transmitted frequencies for international (12 + 12) cable systems. The figure shows two frequency schemes. Scheme 1 has a frequency range from 12 kHz to 120 kHz, with 12 channels numbered 1 to 12. Pilot frequencies are indicated at 60 kHz and 72 kHz. Scheme 2 has a frequency range from 6 kHz to 108 kHz, also with 12 channels numbered 1 to 12. Pilot frequencies are indicated at 54 kHz and 60 kHz. Both schemes show a triangular envelope for the channel frequencies. The text 'CCITT - 45520' is present near Scheme 2. + +FIGURE 1/G.325 + +##### Arrangement of line-transmitted frequencies for international (12 + 12) cable systems + +Administrations concerned in setting up such an international system should agree to use either one or the other of the two schemes. + +#### 2 Line-regulating pilots + +The following frequencies are recommended: + +- with Scheme 1: 60 kHz and 72 kHz; +- with Scheme 2: 54 kHz and 60 kHz. + +The recommended accuracy is $\pm 1$ Hz for the 60-kHz pilot. The frequency tolerance for other pilots will be decided by agreement between the Administrations concerned. + +All these pilots should be transmitted at power level of -15 dBm0. + +#### 3 Hypothetical reference circuit for (12 + 12) symmetric-pair system + +This is 2500 kilometres long, and for each direction of transmission comprises a total of: + +- three channel translation pairs; +- nine special translation pairs translating a basic group into the band transmitted to line, and vice versa. + +This circuit is carried on a (12 + 12) symmetric-pair system in cable, with pairs assumed to be of conductors of 0.9-mm diameter, with an effective capacitance of 35 to 40 nF/km. + +Figure 2/G.325 shows one of the three identical parts of which this hypothetical reference circuit is made up. All in all, it has 18 homogeneous sections, each 140 kilometres long. + +![Diagram of one-third of the hypothetical reference circuit for symmetric pair (12 + 12) systems. The diagram shows two parallel transmission lines. The top line has arrows pointing right, representing transmission in one direction. The bottom line has arrows pointing left, representing transmission in the opposite direction. Each line consists of a series of blocks: a square block (Channel translating equipment) followed by three pairs of a square block and a square block with a diagonal line (Special translation equipment). Above the diagram, a dimension line indicates a total length of 6 x 140 = 840 km. A legend at the bottom left defines the symbols: a square for 'Channel translating equipment' and a square with a diagonal line for 'Special translation equipment (for 1 basic group in the line frequency band)'. A legend on the right shows frequency bands for two schemes: Scheme No. 1 (12-60 kHz for group A, 72-120 kHz) and Scheme No. 2 (60-108 kHz for basic group B, 6-54 kHz). The text 'CCITT - 45530' is in the bottom right corner.](0c9723d1620cf51bc2b7a380ce7e23c0_img.jpg) + +Diagram of one-third of the hypothetical reference circuit for symmetric pair (12 + 12) systems. The diagram shows two parallel transmission lines. The top line has arrows pointing right, representing transmission in one direction. The bottom line has arrows pointing left, representing transmission in the opposite direction. Each line consists of a series of blocks: a square block (Channel translating equipment) followed by three pairs of a square block and a square block with a diagonal line (Special translation equipment). Above the diagram, a dimension line indicates a total length of 6 x 140 = 840 km. A legend at the bottom left defines the symbols: a square for 'Channel translating equipment' and a square with a diagonal line for 'Special translation equipment (for 1 basic group in the line frequency band)'. A legend on the right shows frequency bands for two schemes: Scheme No. 1 (12-60 kHz for group A, 72-120 kHz) and Scheme No. 2 (60-108 kHz for basic group B, 6-54 kHz). The text 'CCITT - 45530' is in the bottom right corner. + +FIGURE 2/G.325 + +##### Basic diagram of one-third of the hypothetical reference circuit for symmetric pair (12 + 12) systems + +*Note 1* - There are only half as many translation pairs as there are homogeneous sections, because one of the two bands transmitted to line corresponds to a basic group (see Figure 2/G.325). + +*Note 2* - With systems using frequency-frogging in the repeaters, the appropriate modulators form part of the high-frequency line. + +#### 4 Design objectives for circuit noise + +The objectives set forth in Recommendation G.222 apply to the hypothetical reference circuit for symmetric-pair (12 + 12) systems, in the circumstances described in Recommendation G.223. + +In practice, it will suffice to check by calculation that the mean psophometric power at the end of every telephone channel as defined by the hypothetical reference circuit, at zero relative level, does not exceed 10 000 pW0p during any hour. + +Provisionally, it is recommended that this overall limit be apportioned between the total noise components as follows: + +- | | | +|--------------------------------------------------------------------------|-----------| +| – line noise (including noise due to special translation equipment)..... | 9000 pW0p | +| – noise due to channel translating equipment ..... | 1000 pW0p | + +Apportionment of total noise inherent in the system among: + +- basic noise, +- intermodulation noise, +- noise due to crosstalk, + +is left entirely to the discretion of the carrier system designer, up to 1000 pW0p for channel translating equipment and 9000 pW0p for the line. + +*Note* - In accordance with all recommendations on cable systems in the Series G Recommendations, the design objective as regards noise power does not take into consideration noise from external sources; it is assumed that this is negligible compared with the figure of 10 000 pW0p. + +With regard to real circuits, Administrations must take whatever steps are required in each individual case to ensure that clicks arising on audio-frequency pairs in the same cable as a (12 + 12) system and transmitted by crosstalk do not create excessive noise on the circuits of that system which may be used for international communications. + +#### 5 Error on the reconstituted frequency + +The difference between a frequency sent at the origin of a homogeneous section 140 km long (see § 3 above and Figure 2/G.325) and the frequency received at the end of that section, should not exceed a figure provisionally fixed at 0.3 Hz; this figure is the same whether there is frequency-frogging in the intermediate repeaters or not. + +#### 6 Direct line interconnection + +When Administrations desire the direct line interconnection of two systems (with, of course, the same allocation of line-transmitted frequencies) it is recommended that each of these systems should meet the following requirements on the interconnection section (except where agreed otherwise between the Administrations concerned): + +- 1) Relative level per channel, at all frequencies, at the output of the frontier repeaters: -15 dBr1). +- 2) Attenuation of the frontier elementary cable section at the highest frequency transmitted to line: 25 dB1). + +*Note* - For composite cables, agreement should be reached between the two Administrations concerned to fix the attenuation of the frontier section in such a way that the repeaters of the symmetric pairs and those of the coaxial cables can be housed in the same frontier stations. + +- 3) Matching of the impedances of the frontier repeaters and the line. The modulus of the return-current coefficient between the input (or output) impedance of a repeater and the characteristic impedance of the line should not exceed the lower of the two values: + +$$0.15 \sqrt{\frac{f_{max}}{f}} \text{ or } 0.25$$ + +--- + +1) These values apply to low-gain systems. They are not valid for high-gain systems, i.e. for systems whose gain is substantially above 30 dB. + +If such interconnection is necessary, either for operating reasons or because the two systems to be interconnected use different allocations of frequencies transmitted to line, one of the following procedures may be followed: + +- 1) interconnection at a group distribution frame, with use of the basic group, levels and impedance applied normally by the Administration to which the frame belongs; +- 2) direct interconnection between the two systems. If they use different allocations of frequencies transmitted to line, the two Administrations concerned shall reach agreement on which of them shall install the necessary demodulators (the line of separation between the two types of equipment will then be CC' or DD' on Figure 3/G.325). + +![Figure 3/G.325: Direct interconnection of two (12 + 12) systems using different allocations of frequencies transmitted to line. The diagram shows two systems, A and B, connected via a central switching or routing area. System A uses frequency allocation 72-120 Sch. 1, and System B uses 6-54 Sch. 2. The connection points are labeled C, C', D, and D'. A diagonal line represents the separation between the two systems. A legend indicates that a square with a diagonal line represents a 'Special group modulator normally used in one of the systems'. The diagram is labeled CCITT - 46540.](f6d72d7c790e7f585532140f3971639a_img.jpg) + +The diagram illustrates the direct interconnection of two (12 + 12) systems, A and B, using different frequency allocations. System A is associated with the frequency range 72-120 Sch. 1, and System B with 6-54 Sch. 2. The connection is shown in two horizontal sections. In the top section, System A's signal enters from the left, passes through a point C, then a modulator (square with diagonal line), and exits to the right. System B's signal enters from the right, passes through a point D, then a modulator, and exits to the left. A diagonal line labeled CC' separates the two systems. In the bottom section, System A's signal enters from the left, passes through a point C', then a modulator, and exits to the right. System B's signal enters from the right, passes through a point D', then a modulator, and exits to the left. A diagonal line labeled DD' separates the two systems. A legend at the bottom left shows a square with a diagonal line and the text 'Special group modulator normally used in one of the systems'. The diagram is labeled CCITT - 46540. + +Figure 3/G.325: Direct interconnection of two (12 + 12) systems using different allocations of frequencies transmitted to line. The diagram shows two systems, A and B, connected via a central switching or routing area. System A uses frequency allocation 72-120 Sch. 1, and System B uses 6-54 Sch. 2. The connection points are labeled C, C', D, and D'. A diagonal line represents the separation between the two systems. A legend indicates that a square with a diagonal line represents a 'Special group modulator normally used in one of the systems'. The diagram is labeled CCITT - 46540. + +FIGURE 3/G.325 + +Direct interconnection of two (12 + 12) systems using different allocations of frequencies transmitted to line + +In the absence of such an agreement, each incoming system must comprise equipment required for the outgoing system, in each direction of transmission (the separating line in Figure 3/G.325 would then be the oblique DC'). + +Unless there is a specific agreement, the relative power level will be -36 dBr at sending (input of each system - points C' and D in the case of Figure 3/G.325). The points considered do not correspond to points T and T' defined in Recommendation G.213. In particular, a translating equipment of any type cannot be connected to it without precautionary measures (see the levels indicated in the Table 1/G.233). + +By agreement between Administrations, interconnection can be effected as indicated in Figure 4/G.325, a method whereby it is possible to replace three modulators by one. + +![Figure 4/G.325: Method of interconnection that can be used by agreement between Administrations. The diagram shows four configurations of modulators (rectangles) and frequency bands (kHz).](1956f44611abd5c3c41049836aa78ad8_img.jpg) + +The diagram illustrates four methods of interconnection between three modulators, labeled I, A, B, and II. The modulators are represented by rectangles, and the frequency bands are indicated by arrows and numbers in kHz. + +- Top Configuration:** A central modulator (126) is connected to three modulators (132, 120, 114) via a common bus. Modulator 132 is connected to frequency bands 72-120 and 12-60. Modulator 120 is connected to frequency band 120. Modulator 114 is connected to frequency bands 6-54 and 60-108. The bus is labeled with 126 at the top and bottom. +- Second Configuration:** Similar to the top configuration, but the bus is labeled with 126 at the top and bottom, and the frequency bands are 12-60 and 72-120 for modulator 132, 120 for modulator 120, and 60-108 and 6-54 for modulator 114. +- Third Configuration:** Modulator 132 is connected to frequency bands 12-60 and 72-120. Modulator 120 is connected to frequency band 120. Modulator 114 is connected to frequency bands 6-54 and 60-108. The bus is labeled with 126 at the top and bottom. +- Bottom Configuration:** Modulator 132 is connected to frequency bands 72-120 and 12-60. Modulator 120 is connected to frequency band 120. Modulator 114 is connected to frequency bands 60-108 and 6-54. The bus is labeled with 126 at the top and bottom. + +The diagram is labeled with CCITT - 46550 at the bottom right. + +Figure 4/G.325: Method of interconnection that can be used by agreement between Administrations. The diagram shows four configurations of modulators (rectangles) and frequency bands (kHz). + +FIGURE 4/G.325 + +Method of interconnection that can be used by agreement between Administrations +(the numbers on this diagram show frequencies in kHz; A and B indicate the basic group concerned) + +#### 8 Essential clauses for a model specification + +See Recommendation G.326. \ No newline at end of file diff --git a/marked/G/T-REC-G.341-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.341-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..2bacea077f963457340d5a48236d8569e24b8886 --- /dev/null +++ b/marked/G/T-REC-G.341-198811-I_PDF-E/raw.md @@ -0,0 +1,209 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.341** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES** --- + +**1.3 MHz SYSTEMS ON STANDARDIZED +1.2/4.4 mm COAXIAL CABLE PAIRS** + +**ITU-T Recommendation G.341** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +1 ITU-T Recommendation G.341 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## 1.3 MHz SYSTEMS ON STANDARDIZED 1.2/4.4 mm COAXIAL CABLE PAIRS + +(amended at Geneva, 1964; further amended) + +### Preliminary note + +The present Recommendation describes two types of systems on coaxial cable pairs providing 300 telephone channels in the approximate frequency band 0.06 to 1.3 MHz. The length of the elementary cable section is about 6 km for the first type of system and about 8 km for the second. The first is to be preferred when it is planned to equip the cable with 6 MHz repeaters later on, the second when it is planned to install systems belonging to the other family on the cable later on, i.e. the 4 MHz system, 12 MHz system or 18 MHz system. + +### 1 Line frequencies + +The system will carry 300 telephony channels, transmitted to line: + +- either between 60 kHz and 1300 kHz as supergroups Nos. 1-5 of the 4 MHz system (Figure 1 a)/G.341); +- or between 64 kHz and 1296 kHz as a mastergroup with erect channel sidebands (Figure 1 b)/G.341). + +![Figure 1/G.341: Line-frequency arrangements for international carrier 1.3-MHz systems on 1.2/4.4-mm coaxial pair. The figure contains two diagrams, (a) and (b). Diagram (a) shows the 'Supergroups Nos. 1 to 5 arrangement' with five supergroups (1-5) in the 60-1300 kHz band. Diagram (b) shows the 'Mastergroup arrangement' with eight supergroups (1'-8) in the 64-1296 kHz band. Both diagrams show frequency bands, pilot frequencies (60, 308, 556, 804, 1056, 1304, 1364 kHz), and channel sidebands.](e3921a931e5c1e184cf30effc70ded74_img.jpg) + +a) Supergroups Nos. 1 to 5 arrangement + +b) Mastergroup arrangement CCITT - 36770 + +Figure 1/G.341: Line-frequency arrangements for international carrier 1.3-MHz systems on 1.2/4.4-mm coaxial pair. The figure contains two diagrams, (a) and (b). Diagram (a) shows the 'Supergroups Nos. 1 to 5 arrangement' with five supergroups (1-5) in the 60-1300 kHz band. Diagram (b) shows the 'Mastergroup arrangement' with eight supergroups (1'-8) in the 64-1296 kHz band. Both diagrams show frequency bands, pilot frequencies (60, 308, 556, 804, 1056, 1304, 1364 kHz), and channel sidebands. + +FIGURE 1/G.341 + +#### Line-frequency arrangements for international carrier 1.3-MHz systems on 1.2/4.4-mm coaxial pair + +### 2 Pilots and additional measuring frequencies + +#### 2.1 Line-regulating pilot + +The CCITT recommends that 1364 kHz be used for the main line-regulating pilot on all regulated-line sections + +crossing a frontier. The main line-regulating pilot is used for automatic correction of cable attenuation with the temperature. + +In any regulated-line section crossing a frontier, it is recommended that in both directions of transmission the Administration on the transmitting side permanently transmit an auxiliary line-regulating pilot at 60 or 308 kHz, as the Administration on the receiving side may choose, so as to provide for additional regulation, for example. + +The frequency accuracy recommended for the pilots is $\pm 1 \times 10^{-5}$ . + +The power level of these pilots should be adjusted at the output of the transmit amplifier to have a nominal value of -10 dBm0. The harmonics of the 60 and 308 kHz pilots should each have a level not higher than -70 dBm0. + +The tolerances for this level are the same as in Recommendation G.332, § 2.1. + +*Note* - Some systems in use employ a pilot at -1.2 Nm0. + +#### 2.2 *Frequency-comparison pilots* + +For national frequency comparison, it is recommended that a 60 or 308 kHz pilot be used. Should international frequency comparison appear desirable, the Administrations concerned will reach agreement on which of these two frequencies they will use. + +The power level of a frequency-comparison pilot should be adjusted at the output of the transmit amplifier, to a nominal value of -10 dBm0. The harmonics of the frequency-comparison pilots should each have a level not higher than -70 dBm0. + +#### 2.3 *Additional measuring frequencies* + +Frequencies that can be used as additional measuring frequencies are as follows: + +- supergroups Nos. 1 to 5 frequency allocation: (60), (308), 556, 808, 1056, 1304 kHz; +- mastergroup frequency allocation: (60), (308), 804, 1052, 1304 kHz. + +*Note* - One of the two frequencies in brackets will be used for the auxiliary line-regulating pilot. + +The power level of these additional measuring frequencies should be adjusted, at the output of the transmit amplifier, to have a nominal value of -10 dBm0. The harmonics of the additional measuring frequencies below 650 kHz should each have a level at this point not higher than -70 dBm0. + +*Note* - Some systems in use employ additional pilots at -1.2 Nm0. + +The additional measuring frequencies should not be permanently transmitted. They will be transmitted only for as long as is necessary for actual measurement purposes. + +### 3 **Hypothetical reference circuit** + +The CCITT has defined two hypothetical reference circuits, one for supergroup arrangement and the other for mastergroup arrangement. Both are 2500 km long and are divided into nine homogeneous sections of 280 km each. + +#### 3.1 *Hypothetical reference circuit used in supergroup arrangement1)* + +This hypothetical reference circuit (see Figure 2/G.341) has, for each direction of transmission, a total of: + +- three pairs of channel modulators, each pair including translation from the audio-frequency band to the basic group and vice versa; +- six pairs of group modulators, each pair including translation from the basic group to the basic supergroup + +--- + +1) This hypothetical reference circuit is also used for 4 MHz and 6 MHz systems transmitting supergroups on 1.2/4.4 mm coaxial pairs and for systems providing two supergroups on symmetric pairs. + +and vice versa; + +- nine pairs of supergroup modulators, each pair including translation from the basic supergroup to the frequency band transmitted on the coaxial cable and vice versa. + +It will be seen that there is a total of 18 modulations and 18 demodulations for each direction of transmission, assuming that each modulation or demodulation is carried out in a single stage. + +![Diagram of the hypothetical reference circuit for 1.3-MHz systems on coaxial cable using supergroup arrangement. The diagram shows a 2500 km transmission line with various frequency bands and modulators. From left to right, the components are: a modulator, a label 'Frequency band transmitted over the coaxial cable', a modulator, a label 'Audio-frequency band', a modulator, a label 'Basic group frequency band', a modulator, a label 'Basic supergroup frequency band', and a final modulator. The diagram is labeled 'CCITT - 45740' at the far right.](aa81b9b80bd1e3d723922b3a033564a2_img.jpg) + +The diagram illustrates a 2500 km hypothetical reference circuit. It features a horizontal line representing the transmission path with vertical markers and various rectangular blocks representing modulation/demodulation equipment. Labels below the line indicate specific frequency bands: 'Frequency band transmitted over the coaxial cable', 'Audio-frequency band', 'Basic group frequency band', and 'Basic supergroup frequency band'. Arrows point from these labels to specific points on the circuit. The rightmost label is 'CCITT - 45740'. + +Diagram of the hypothetical reference circuit for 1.3-MHz systems on coaxial cable using supergroup arrangement. The diagram shows a 2500 km transmission line with various frequency bands and modulators. From left to right, the components are: a modulator, a label 'Frequency band transmitted over the coaxial cable', a modulator, a label 'Audio-frequency band', a modulator, a label 'Basic group frequency band', a modulator, a label 'Basic supergroup frequency band', and a final modulator. The diagram is labeled 'CCITT - 45740' at the far right. + +FIGURE 2/G.341 + +##### **Diagram of the hypothetical reference circuit for 1.3-MHz systems on coaxial cable using supergroup arrangement** + +#### **3.2 Hypothetical reference circuit used in mastergroup arrangement** + +This hypothetical reference circuit (see Figure 3/G.341) has, for each direction of transmission, a total of: + +- three pairs of channel modulators, each pair including translation from the audio-frequency band to the basic group and vice versa; +- three pairs of group modulators, each pair including translation from the basic group to the basic supergroup and vice versa; +- six pairs of supergroup modulators, each pair including translation from the basic supergroup to the frequency band of the basic mastergroup and vice versa; +- nine pairs of mastergroup modulators, each pair including translation from the basic mastergroup to the frequency band transmitted on the coaxial cable and vice versa. + +![Diagram of a hypothetical reference circuit for 1.3-MHz coaxial pair systems using mastergroup arrangement. The diagram shows a 2500 km transmission line with various frequency bands and modulators. From left to right, the components are: a modulator, a label 'Line-frequency band', a modulator, a label 'Audio-frequency band', a modulator, a label 'Basic supergroup frequency band', a modulator, a label 'Basic mastergroup frequency band', and a final modulator. The diagram is labeled 'CCITT - 45620' at the far right.](b4a7906eddfd40aaa750e19e56c94a8b_img.jpg) + +This diagram shows a 2500 km hypothetical reference circuit for mastergroup arrangement. Similar to Figure 2, it depicts a transmission line with equipment blocks. Labels below the line identify: 'Line-frequency band', 'Audio-frequency band', 'Basic supergroup frequency band', and 'Basic mastergroup frequency band'. Arrows indicate the corresponding points in the circuit. The rightmost label is 'CCITT - 45620'. + +Diagram of a hypothetical reference circuit for 1.3-MHz coaxial pair systems using mastergroup arrangement. The diagram shows a 2500 km transmission line with various frequency bands and modulators. From left to right, the components are: a modulator, a label 'Line-frequency band', a modulator, a label 'Audio-frequency band', a modulator, a label 'Basic supergroup frequency band', a modulator, a label 'Basic mastergroup frequency band', and a final modulator. The diagram is labeled 'CCITT - 45620' at the far right. + +FIGURE 3/G.341 + +##### **Diagram of a hypothetical reference circuit for 1.3-MHz coaxial pair systems using mastergroup arrangement** + +### **4 Circuit noise** + +The general target noise values for cable systems (see Recommendation G.222) apply also to systems on 1.2/4.4 mm coaxial pairs, with the conditions given in Recommendation G.223. + +In practice, it is sufficient to check by calculation that, for every telephone channel as defined by the relevant + +hypothetical reference circuit, the mean psophometric power at the end of the channel, referred to a zero relative level point, does not exceed 10 000 pW0p during any period of one hour. + +### 5 Matching of the coaxial pair impedance and the repeater impedances + +The sum $N$ of three terms defined in Recommendation G.332, § 5 must be at least equal to: + +- 54 dB for a 6 km elementary cable section; +- 52 dB for an 8 km elementary cable section. + +These figures have been calculated so as to get a ripple in the attenuation/frequency characteristic not exceeding 0.8 dB at the end of a homogeneous section 280 km long. It has been assumed that the reflected currents add in phase in all the elementary cable sections of this homogeneous section (the spacing of the buried repeaters, on a small coaxial pair, generally being very regular). In addition, it has been assumed that it is highly improbable that a telephone channel will be on more than one homogeneous section of the hypothetical reference circuit in the lower part of the band of line frequencies. At higher frequencies, $N$ should be well above the limit. + +### 6 Relative levels and interconnection + +#### 6.1 *Relative levels and cabling loss for any repeater section* + +6.1.1 The loss on any 6 km elementary cable section should be 35 dB at 1300 kHz. The relative power level at the input of the cable section (output of the repeater equipment) should be -13 dBr at 1300 kHz. Each Administration may so select the pre-emphasis characteristic that the level at this point and at frequency 60 kHz lies in the range -18 to -28 dBr. + +6.1.2 The nominal loss on any 8 km elementary cable section should be 49 dB at 1300 kHz. The relative levels at the input of any cable section are not strictly standardized, values of -3.5 dBr and -4.3 dBr at the top channel are being used in connection with pre-emphasis values of 9 dB and 10 dB respectively. + +#### 6.2 *Frontier section* + +For interconnection between two systems using different pre-emphasis characteristics, unless there are special arrangements between the Administrations concerned, the following recommendation will be applied: + +6.2.1 In a 6 km elementary cable section crossing a frontier, the level at the end of the cable section (input of the repeater equipment) should be equal to -48 dBr at 1300 kHz. + +As it may be necessary to insert equipment at the frontier crossing to eliminate the monitoring or fault-locating frequencies used in each country or to terminate the remote power supply section, it is possible that the sending relative power level at 1300 kHz may be less than -13 dBr. It is then necessary that the frontier section should be less than 6 km long. If the difference between the pre-emphasis characteristics used in both countries is too great to be compensated for in this way, one of the Administrations concerned, chosen by mutual agreement, will have to make up for this difference at the attended receiving station on its territory which lies closest to the frontier. + +6.2.2 For interconnection between two different systems of this type with 8-km elementary cable sections, the relative level at the frequency 1300 kHz should be -4.0 dBr at the input of the frontier cable section. According to Recommendation G.352 one of the Administrations concerned, chosen by mutual agreement, will have to make up for the slight differences in relative level and pre-emphasis at the attended repeater station which lies closest to the frontier. + +#### 6.3 *Relative levels in a terminal station; interconnection with other systems* + +Recommendation G.213 explains the general principles to be adopted to facilitate interconnection of different systems in terminal stations. + +### 7 Power-feeding and alarm systems + +#### 7.1 *Power-feeding across a frontier* + +In the absence of a special agreement between the Administrations concerned with a power-feeding section crossing a frontier, it is recommended that each Administration power-feed only those repeater stations in its own country. Many Administrations use looped power-feeding on the two sides of a power-feeding station, half of each of the sections between this station and the adjacent power stations being so fed; they can close the loop at their frontier stations. Agreements will be necessary if, for example, the frontier is very far from the mid-point between the two nearest feeding stations, or if the Administrations concerned use looped power-feeding on the entire section between two feeding stations. + +If the repeater stations in a country are fed from another country, special precautions will be required to protect the staff working on the cables. + +#### 7.2 *Remote power-feeding systems* + +The CCITT is studying these systems from the following viewpoints: + +- precautions to be taken to protect staff against normal voltages and remote power-feed currents, or the use of voltages and currents which are innocuous to persons working in repeater stations or on lines; +- protection of staff and equipment against induced voltages and currents; +- trouble in remote power-feeding operation caused by induced voltages and currents. + +#### 7.3 *Supervision and alarms in a frontier section* + +This should be governed by agreement between the Administrations concerned. In particular, it is necessary at the points of interconnection between two systems that if frequencies are used for monitoring or for locating faults they be attenuated to a level of -50 dBm0 on the receiving sides to prevent any disturbance to similar frequencies used in the system farther down the line. + +*Note* - Frequencies sent only over a system already withdrawn from service because of a fault may be selected by each Administration on the national level. \ No newline at end of file diff --git a/marked/G/T-REC-G.346-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.346-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.346-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.346-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.346-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..72b91a341a34bc48c518323116052d446466c08a --- /dev/null +++ b/marked/G/T-REC-G.346-198811-I_PDF-E/raw.md @@ -0,0 +1,45 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.346** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +# **INTERNATIONAL ANALOGUE CARRIER SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES** --- + +**18 MHz SYSTEMS ON STANDARDIZED +1.2/4.4 mm COAXIAL CABLE PAIRS** + +**ITU-T Recommendation G.346** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +- 1 ITU-T Recommendation G.346 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## Recommendation G.346 + +### 18 MHz SYSTEMS ON STANDARDIZED 1.2/4.4 mm COAXIAL CABLE PAIRS + +*(Geneva, 1980)* + +The provisions of this Recommendation are those appearing in Recommendation G.334 for 18 MHz systems on 2.6/9.5 mm coaxial pair, with the exception of the following provision: + +### 5 Matching of repeater and line impedances + +For an elementary cable section about 2 km in length, the recommended value of $N$ is 63 dB throughout the transmitted frequency band, $N$ being defined as in Recommendation G.332, § 5. \ No newline at end of file diff --git a/marked/G/T-REC-G.411-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.411-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.411-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.411-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.411-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..6a2fefb152d12bd0414eca16194e59d1cae83fae --- /dev/null +++ b/marked/G/T-REC-G.411-198811-I_PDF-E/raw.md @@ -0,0 +1,57 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.411** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**INTERNATIONAL ANALOGUE CARRIER SYSTEMS +GENERAL CHARACTERISTICS OF INTERNATIONAL +CARRIER TELEPHONE SYSTEMS ON +RADIO - RELAY OR SATELLITE LINKS AND +INTERCONNECTION WITH METALLIC LINES** + +--- + +**USE OF RADIO - RELAY SYSTEMS FOR +INTERNATIONAL TELEPHONE CIRCUITS** + +**ITU-T Recommendation G.411** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +- 1 ITU-T Recommendation G.411 was published in Fascicle III.2 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## Recommendation G.411 + +# USE OF RADIO-RELAY SYSTEMS FOR INTERNATIONAL TELEPHONE CIRCUITS + +The CCITT + +*unanimously recommends1)* + +that, between fixed points, telephone communications should be effected wherever possible by means of metallic conductors or radio-relay links using frequencies above 30 MHz to make the allocation of radio-frequencies less difficult and, where this can be realized, the objective should be to attain the transmission performance recommended by the CCITT for international telephone circuits on metallic conductors. + +## Reference + +- [1] CCIR Recommendation *Use of radio links in international telephone circuits*, Vol. III, Rec. 335, Dubrovnik, 1986. + +--- + +1) This Recommendation is the same as an extract from CCIR Recommendation 335 [1]. \ No newline at end of file diff --git a/marked/G/T-REC-G.621-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.621-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.621-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.640-200603-I_PDF-E/raw.md b/marked/G/T-REC-G.640-200603-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..c86755095e4fbe4fc1bc827557ea9526d3e15f29 --- /dev/null +++ b/marked/G/T-REC-G.640-200603-I_PDF-E/raw.md @@ -0,0 +1,639 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.640** + +(03/2006) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Transmission media characteristics – Submarine cables + +--- + +**Co-location longitudinally compatible interfaces +for free space optical systems** + +ITU-T Recommendation G.640 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| General | G.600–G.609 | +| Symmetric cable pairs | G.610–G.619 | +| Land coaxial cable pairs | G.620–G.629 | +| Submarine cables | G.630–G.649 | +| Optical fibre cables | G.650–G.659 | +| Characteristics of optical components and subsystems | G.660–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| ETHERNET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.640** + +## **Co-location longitudinally compatible interfaces for free space optical systems** + +## **Summary** + +This Recommendation provides a procedure for establishing that two co-located Free Space Optical (FSO) transmission systems will not interfere with each other. Calculations of the conditions required to be met to prevent interference in some examples of co-located FSO systems are also included. + +### **Source** + +ITU-T Recommendation G.640 was approved on 29 March 2006 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2006 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +| | Page | +|---------------------------------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 2.1 Normative references..... | 1 | +| 2.2 Informative references..... | 1 | +| 3 Terms and definitions ..... | 1 | +| 3.1 Definitions ..... | 1 | +| 3.2 Terms defined in other Recommendations..... | 2 | +| 4 Abbreviations..... | 2 | +| 5 Reference points ..... | 3 | +| 6 Co-location longitudinal compatibility..... | 3 | +| 6.1 Crosstalk ratio between two FSO systems ..... | 5 | +| 6.2 Effect of the weather on crosstalk ratio ..... | 9 | +| 6.3 Case A – interference between two systems that can be at the same wavelength..... | 10 | +| 6.4 Case B – interference between two systems which cannot be at the same wavelength..... | 11 | +| 6.5 Procedure for establishing whether the conditions for co-location longitudinal compatibility are met..... | 12 | +| 7 Optical safety considerations..... | 13 | +| Appendix I – Example crosstalk calculations ..... | 13 | +| I.1 Example 1 ..... | 13 | +| I.2 Example 2 ..... | 15 | +| I.3 Example 3 ..... | 16 | + + + +## ITU-T Recommendation G.640 + +## Co-location longitudinally compatible interfaces for free space optical systems + +# 1 Scope + +This Recommendation defines optical interfaces for "co-location longitudinally compatible" free space optical transmission systems thereby enabling interference-free coexistence of more than one point-to-point free space optical system at a location. + +This Recommendation also includes definitions of parameters that are relevant for the characterization of free space optical systems. + +Free space optical systems are commonly referred to as "FSO" systems. + +# 2 References + +## 2.1 Normative references + +The following ITU-T Recommendations and other references contain provisions, which through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- ITU-T Recommendation G.957 (2006), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy*. +- IEC 60825-1 (2001), *Safety of laser products – Part 1: Equipment classification, requirements and user's guide*. +- IEC 60825-2 (2005), *Safety of laser products – Part 2: Safety of optical fibre communication systems (OFCS)*. +- IEC 60825-12 (2005), *Safety of laser products – Part 12: Safety of free space optical communication systems used for transmission of information*. + +## 2.2 Informative references + +- ITU-T G-series Recommendations – Supplement 39 (2006), *Optical system design and engineering considerations*. + +# 3 Terms and definitions + +## 3.1 Definitions + +This Recommendation defines the following terms: + +**3.1.1 acceptance angle:** The acceptance angle (of an FSO receiver) is the angle between the lines at which the power detected by the receiver falls to $1/e^2$ . This parameter is also called the Field of View (FOV) of an FSO receiver and is commonly defined to be where the power density falls to $1/e^2$ , $1/e$ or 50%. + +**3.1.2 beam divergence:** The beam divergence is the angle between the lines at which the power density of an FSO beam falls to $1/e^2$ . + +NOTE 1 – This parameter is also commonly defined to be where the power density falls to either $1/e$ or 50%. + +NOTE 2 – The beam divergence should be measured at a distance at least five times the Rayleigh distance from the lens (see 3.1.8) to ensure that it is measured under far field conditions. + +**3.1.3 inter-channel crosstalk:** The ratio of the disturbing optical power to the wanted optical power detected by the receiver where the wanted and disturbing signals are at different wavelengths. + +**3.1.4 inter-channel crosstalk penalty:** The penalty assigned in the system budget to account for inter-channel crosstalk. + +**3.1.5 interferometric crosstalk:** The ratio of the disturbing optical power to the wanted optical power detected by the receiver where the wanted and disturbing signals can be at the same wavelength. + +**3.1.6 interferometric crosstalk penalty:** The penalty assigned in the system budget to account for interferometric crosstalk. + +**3.1.7 transmitter (or receiver) setting error:** The maximum angle between the axis of the transmitter (or receiver) and a straight line joining the transmitter and receiver together. + +**3.1.8 Rayleigh distance:** This is defined as: + +$$\text{Rayleigh distance} = \frac{2D^2}{\lambda}$$ + +where: + +D is the diameter of the transmitter lens + +$\lambda$ is the wavelength + +## 3.2 Terms defined in other Recommendations + +This Recommendation uses the following term defined in ITU-T Rec. G.957: + +- Extinction ratio. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +FOV Field Of View + +FSO Free Space Optical + +$R_{\text{fso}}$ Reference plane just before the optical receiver input lens + +Rx Receiver + +$S_{\text{fso}}$ Reference plane just after the optical transmitter output lens + +Tx Transmitter + +# 5 Reference points + +![Figure 5-1/G.640 – Free space optical link reference diagram. The diagram shows two 'FSO Black-Boxes' connected by an 'FSO link'. Each black box contains an 'Interface unit' and a transceiver with 'Tx' (transmitter) and 'Rx' (receiver) components. The reference planes are labeled: S_fso (just after the Tx output lens), R_fso (just before the Rx input lens) for the left box, and R_fso (just after the Tx output lens), S_fso (just before the Rx input lens) for the right box. The diagram is labeled G.640_F1 in the bottom right corner.](acfc53eca625d62b38aa2563efa95c3e_img.jpg) + +The diagram illustrates the reference points for a free space optical (FSO) link. Two dashed boxes represent the 'FSO Black-Boxes'. Inside each box is an 'Interface unit' connected to a transceiver with 'Tx' (transmitter) and 'Rx' (receiver) components. The reference planes are defined as follows: $S_{\text{fso}}$ is a reference plane just after the optical transmitter output lens, and $R_{\text{fso}}$ is a reference plane just before the optical receiver input lens. The 'FSO link' is the free space between the $S_{\text{fso}}$ plane of one box and the $R_{\text{fso}}$ plane of the other. The diagram is labeled G.640\_F1 in the bottom right corner. + +Figure 5-1/G.640 – Free space optical link reference diagram. The diagram shows two 'FSO Black-Boxes' connected by an 'FSO link'. Each black box contains an 'Interface unit' and a transceiver with 'Tx' (transmitter) and 'Rx' (receiver) components. The reference planes are labeled: S\_fso (just after the Tx output lens), R\_fso (just before the Rx input lens) for the left box, and R\_fso (just after the Tx output lens), S\_fso (just before the Rx input lens) for the right box. The diagram is labeled G.640\_F1 in the bottom right corner. + +**Figure 5-1/G.640 – Free space optical link reference diagram** + +The reference planes in Figure 5-1 are defined as follows: + +- $S_{\text{fso}}$ is a reference plane just after the optical transmitter output lens; +- $R_{\text{fso}}$ is a reference plane just before the optical receiver input lens. + +# 6 Co-location longitudinal compatibility + +The free space between the $S_{\text{fso}}$ and $R_{\text{fso}}$ reference planes in an FSO system is a shared medium employed by many other users for a variety of different purposes. In order to establish criteria for the co-location of FSO systems, the crosstalk ratio $C$ generated by one system interfering with another is described in 6.1 and the effect of the weather on this crosstalk ratio is considered in 6.2. The optical power penalty caused by this crosstalk is then defined for two cases: + +- Case A – where the two systems can be at the same wavelength (see 6.3). +- Case B – where the two systems can **not** be at the same wavelength (see 6.4). + +The difference between these two cases is illustrated in Figure 6-1. + +![Figure 6-1/G.640 – Illustration of the difference between the cases covered by clauses 6.3 and 6.4. The figure contains two diagrams, Case A and Case B, plotted on a 'Wavelength' axis. Case A (see 6.3) shows two adjacent shaded rectangles representing the 'Possible wavelength range of Tx1' and 'Possible wavelength range of Tx2'. An arrow points to the boundary between them with the text 'Overlap between ranges, or gap smaller than the equivalent of the receiver electrical bandwidth'. Case B (see 6.4) shows two separate shaded rectangles for the same transmitter ranges. An arrow points to the gap between them with the text 'Gap between ranges of at least the equivalent of the receiver electrical bandwidth'. A label 'G.640_F6-1' is in the bottom right of the figure area.](4e0ade2f41b66d5602160da5cc978274_img.jpg) + +Possible wavelength range of Tx1 + +Possible wavelength range of Tx2 + +Case A (see 6.3) + +Overlap between ranges, or gap smaller than the equivalent of the receiver electrical bandwidth + +Wavelength + +Possible wavelength range of Tx1 + +Possible wavelength range of Tx2 + +Case B (see 6.4) + +Gap between ranges of at least the equivalent of the receiver electrical bandwidth + +Wavelength + +G.640\_F6-1 + +Figure 6-1/G.640 – Illustration of the difference between the cases covered by clauses 6.3 and 6.4. The figure contains two diagrams, Case A and Case B, plotted on a 'Wavelength' axis. Case A (see 6.3) shows two adjacent shaded rectangles representing the 'Possible wavelength range of Tx1' and 'Possible wavelength range of Tx2'. An arrow points to the boundary between them with the text 'Overlap between ranges, or gap smaller than the equivalent of the receiver electrical bandwidth'. Case B (see 6.4) shows two separate shaded rectangles for the same transmitter ranges. An arrow points to the gap between them with the text 'Gap between ranges of at least the equivalent of the receiver electrical bandwidth'. A label 'G.640\_F6-1' is in the bottom right of the figure area. + +**Figure 6-1/G.640 – Illustration of the difference between the cases covered by clauses 6.3 and 6.4** + +For bidirectional systems the two directions have to be considered separately. + +NOTE 1 – For some FSO systems the source coherence is sufficiently low (especially in the case of LED-based systems) that even when the wavelengths are the same, interferometric crosstalk is not observed. For these co-located FSO systems, case B always applies. + +NOTE 2 – Even for some laser-based FSO systems, the assumption of interferometric crosstalk may be pessimistic because the laser coherence may be largely destroyed by the atmosphere at some wavelengths. + +## 6.1 Crosstalk ratio between two FSO systems + +On the assumption that the beam produced by an FSO transmitter can be approximated by a Gaussian beam, Figure 6-2 contains a reference diagram for a general FSO transmitter. + +![Figure 6-2/G.640 – Gaussian beam reference diagram for an FSO transmitter. The diagram shows an FSO black box containing a Laser Tx. A beam axis extends from the laser through a reference plane S_fso. The beam diverges at an angle d, forming a Gaussian profile. The optical power density at the center of the beam is O_c. The beam axis is labeled. Two surfaces are shown where the power density has fallen to P_c/e^2. The angle between the beam axis and the measurement point is theta.](e9314c83043183351ed74908e9bf2f90_img.jpg) + +The diagram illustrates a Gaussian beam profile originating from a laser transmitter (Laser Tx) within an FSO black box. A reference plane $S_{\text{fso}}$ is defined at the output aperture. The beam axis is a horizontal line extending from the laser. The beam divergence angle $d$ is the angle between the beam axis and the lines where the power density has fallen to $1/e^2$ of the central value. The optical power density at the center of the beam is $O_c$ . The angle $\theta$ is the angle between the beam axis and the measurement point. The surfaces where the power density has fallen to $P_c/e^2$ are shown as dashed ellipses. + +Figure 6-2/G.640 – Gaussian beam reference diagram for an FSO transmitter. The diagram shows an FSO black box containing a Laser Tx. A beam axis extends from the laser through a reference plane S\_fso. The beam diverges at an angle d, forming a Gaussian profile. The optical power density at the center of the beam is O\_c. The beam axis is labeled. Two surfaces are shown where the power density has fallen to P\_c/e^2. The angle between the beam axis and the measurement point is theta. + +Figure 6-2/G.640 – Gaussian beam reference diagram for an FSO transmitter + +The optical power density of this beam at an angle $\theta$ to the beam axis is given by: + +$$O = O_c e^{-\frac{\theta^2}{d^2}} \quad (6-1)$$ + +where: + +- $O_c$ is the optical power density at the centre of the beam +- $d$ is the beam divergence (the angle between the lines at which the power density falls to $1/e^2$ ) and +- $\theta$ is the angle between the beam axis and the measurement point + +If the curve of optical power density vs angle is known for a particular FSO system, then values from the curve should be used in place of the approximation from Equation 6-1. An example measured curve is shown in Figure 6-3. + +![Figure 6-3/G.640: Example measured curve of power density vs angle. The graph plots Relative power (dB) on the y-axis (from -30 to 5) against Angle from axis θ (mrad) on the x-axis (from -4 to 4). A solid blue line with markers represents the 'Measured characteristic', which peaks at 0 dB at 0 mrad and drops to about -22 dB at ±3 mrad. A dashed black line represents the 'Gaussian approximation with the same beam divergence', which follows the measured curve closely. A horizontal dashed red line at approximately -8.7 dB is labeled 1/e².](36ac3e730a00d3f42d3400f5709f641a_img.jpg) + +Figure 6-3/G.640: Example measured curve of power density vs angle. The graph plots Relative power (dB) on the y-axis (from -30 to 5) against Angle from axis θ (mrad) on the x-axis (from -4 to 4). A solid blue line with markers represents the 'Measured characteristic', which peaks at 0 dB at 0 mrad and drops to about -22 dB at ±3 mrad. A dashed black line represents the 'Gaussian approximation with the same beam divergence', which follows the measured curve closely. A horizontal dashed red line at approximately -8.7 dB is labeled 1/e². + +**Figure 6-3/G.640 – Example measured curve of power density vs angle** + +The corresponding reference diagram for the FSO receiver is given in Figure 6-4. + +![Figure 6-4/G.640: Reference diagram for an FSO receiver. The diagram shows a receiver (Rx) represented by a yellow oval. A horizontal dash-dot line represents the receiver axis. A red dashed line at an angle φ from the axis represents the surface where power has fallen by 1/e². A blue dashed line at an angle a from the axis represents another surface where power has fallen by 1/e². Labels include 'Surface along which power detected by receiver has fallen by 1/e²' for both lines, 'φ', 'a', and 'Rx'.](27b06ec9f42b5d727a2630f61a5f1861_img.jpg) + +Figure 6-4/G.640: Reference diagram for an FSO receiver. The diagram shows a receiver (Rx) represented by a yellow oval. A horizontal dash-dot line represents the receiver axis. A red dashed line at an angle φ from the axis represents the surface where power has fallen by 1/e². A blue dashed line at an angle a from the axis represents another surface where power has fallen by 1/e². Labels include 'Surface along which power detected by receiver has fallen by 1/e²' for both lines, 'φ', 'a', and 'Rx'. + +**Figure 6-4/G.640 – Reference diagram for an FSO receiver** + +The characteristic of detected power vs angle for an FSO receiver depends on a number of parameters including the focal length of the lens, the lens quality, and the diameter of the detector. + +If the diameter of the spot formed by the lens is smaller than the diameter of the detector, then the characteristic is approximately rectangular. However, if the diameter of the spot is approximately the same as the diameter of the detector, then the characteristic is an approximately Gaussian curve where the optical power (incident at an angle $\phi$ to the receiver axis) detected by the receiver is given by: + +$$R = R_a e^{\frac{-8\phi^2}{a^2}} \quad (6-2)$$ + +where: + +$R_a$ is the optical power detected by the receiver when the light is incident along the receiver axis + +$a$ is the acceptance angle (the angle between the lines at which the power detected by the receiver falls to $1/e^2$ ) + +$\phi$ is the angle between the incident light and the axis of the receiver + +The two cases defined above are illustrated in Figures 6-5 and 6-6. + +![Figure 6-5/G.640: Example measured curve of received power vs angle showing a rectangular shape. The graph plots Relative received power (dB) on the y-axis (from -30 to 0) against Angle from axis φ (mrad) on the x-axis (from -5 to 5). A solid blue line represents the 'Measured characteristic of an FSO receiver', which is flat at 0 dB between approximately -1.5 and 1.5 mrad and drops sharply to -30 dB outside this range. A dashed black line represents a 'Gaussian curve' that follows the flat top of the measured curve. A horizontal red dashed line at approximately -8.7 dB indicates the 1/e² power level. The label G.640_F6-5 is in the bottom right corner.](8791f79b259a7463279c1aeb14c31580_img.jpg) + +Figure 6-5/G.640: Example measured curve of received power vs angle showing a rectangular shape. The graph plots Relative received power (dB) on the y-axis (from -30 to 0) against Angle from axis φ (mrad) on the x-axis (from -5 to 5). A solid blue line represents the 'Measured characteristic of an FSO receiver', which is flat at 0 dB between approximately -1.5 and 1.5 mrad and drops sharply to -30 dB outside this range. A dashed black line represents a 'Gaussian curve' that follows the flat top of the measured curve. A horizontal red dashed line at approximately -8.7 dB indicates the 1/e² power level. The label G.640\_F6-5 is in the bottom right corner. + +**Figure 6-5/G.640 – Example measured curve of received power vs angle showing a rectangular shape** + +![Figure 6-6/G.640: Example measured curve of received power vs angle showing a Gaussian shape. The graph plots Relative received power (dB) on the y-axis (from -20 to 0) against Angle from axis φ (mrad) on the x-axis (from -10 to 10). A solid blue line represents the 'Measured characteristic of an FSO receiver', which has a smooth, rounded peak at 0 dB. A dashed black line represents a 'Gaussian approximation' that closely follows the measured curve. A horizontal red dashed line at approximately -8.7 dB indicates the 1/e² power level. The label G.640_F6-6 is in the bottom right corner.](c222a9006d6d60a8d81e6ffbfc0e74ad_img.jpg) + +Figure 6-6/G.640: Example measured curve of received power vs angle showing a Gaussian shape. The graph plots Relative received power (dB) on the y-axis (from -20 to 0) against Angle from axis φ (mrad) on the x-axis (from -10 to 10). A solid blue line represents the 'Measured characteristic of an FSO receiver', which has a smooth, rounded peak at 0 dB. A dashed black line represents a 'Gaussian approximation' that closely follows the measured curve. A horizontal red dashed line at approximately -8.7 dB indicates the 1/e² power level. The label G.640\_F6-6 is in the bottom right corner. + +**Figure 6-6/G.640 – Example measured curve of received power vs angle showing a Gaussian shape** + +As can be seen from Figure 6-5, the fit between the measured characteristic and the Gaussian curve is not very good for the rectangular case. + +Consequently, if the curve of optical power detected by the receiver vs angle is known for a particular FSO system, then values from the curve should be used in place of the approximation from Equation 6-2. + +For the case where the two systems cannot be at the same wavelength, optical filtering at the receiver may further reduce the amount of interfering power detected with respect to the wanted power. This effect is illustrated in Figure 6-7. + +![Figure 6-7/G.640 – Illustration of reduction of the interfering power due to optical filtering. The graph shows Filter loss (dB) on the y-axis and Wavelength on the x-axis. A U-shaped curve represents the filter loss. Two shaded rectangular regions on the x-axis represent the 'Possible wavelength range of interferer' and the 'Possible wavelength range of wanted transmitter'. The vertical distance between the filter loss curve at the interferer's wavelength range and the wanted transmitter's wavelength range is labeled 'Minimum loss over interferer wavelength range' and 'Maximum loss over wanted wavelength range'. The difference in loss between these two points is labeled '10Log(L)'.](0332672e127cd13bb6d2fc8d1e27bfa2_img.jpg) + +Figure 6-7/G.640 – Illustration of reduction of the interfering power due to optical filtering. The graph shows Filter loss (dB) on the y-axis and Wavelength on the x-axis. A U-shaped curve represents the filter loss. Two shaded rectangular regions on the x-axis represent the 'Possible wavelength range of interferer' and the 'Possible wavelength range of wanted transmitter'. The vertical distance between the filter loss curve at the interferer's wavelength range and the wanted transmitter's wavelength range is labeled 'Minimum loss over interferer wavelength range' and 'Maximum loss over wanted wavelength range'. The difference in loss between these two points is labeled '10Log(L)'. + +**Figure 6-7/G.640 – Illustration of reduction of the interfering power due to optical filtering** + +Figure 6-8 shows the general case of one FSO system interfering with another. + +![Figure 6-8/G.640 – FSO system crosstalk reference diagram. This 3D diagram shows a 'Wanted Tx' (transmitter) and an 'Interfering Tx' (transmitter) both pointing towards a common 'Rx' (receiver). The wanted transmitter's beam is shown with dashed lines and an angle 'a'. The interfering transmitter's beam is shown with solid lines and an angle 'd'. The receiver has two apertures, 'Ow' (wanted) and 'Oi' (interfering). The angle between the wanted transmitter's beam and the receiver's wanted aperture is 'phi'. The angle between the interfering transmitter's beam and the receiver's interfering aperture is 'theta'. The distance between the two transmitters is labeled 'd'.](1b5a812c8aa20fd5cba28e97001d32de_img.jpg) + +Figure 6-8/G.640 – FSO system crosstalk reference diagram. This 3D diagram shows a 'Wanted Tx' (transmitter) and an 'Interfering Tx' (transmitter) both pointing towards a common 'Rx' (receiver). The wanted transmitter's beam is shown with dashed lines and an angle 'a'. The interfering transmitter's beam is shown with solid lines and an angle 'd'. The receiver has two apertures, 'Ow' (wanted) and 'Oi' (interfering). The angle between the wanted transmitter's beam and the receiver's wanted aperture is 'phi'. The angle between the interfering transmitter's beam and the receiver's interfering aperture is 'theta'. The distance between the two transmitters is labeled 'd'. + +**Figure 6-8/G.640 – FSO system crosstalk reference diagram** + +This leads to an equation for the crosstalk ratio $C$ : + +$$C = L \frac{O_I}{O_W} e^{\frac{-8\theta^2}{d^2}} e^{\frac{-8\phi^2}{a^2}} \quad (6-3)$$ + +where: + +- $L$ is the ratio of optical filter loss between the wanted and interfering wavelength ranges as illustrated in Figure 6-7 (this would be 1 if the ranges overlap (Case A) or if both ranges are within a flat region of the filter characteristic) +- $O_W$ is the minimum power density at the centre of the wanted beam +- $O_I$ is the maximum power density at the centre of the interfering beam at the same distance from the interfering transmitter as the receiver +- $\theta$ is the angle between the interfering beam axis and a line between the interfering transmitter and the receiver +- $d$ is the beam divergence (the angle between the lines at which the power density falls to $1/e^2$ ) of the interfering transmitter +- $\phi$ is the angle between the receiver axis and a line between the interfering transmitter and the receiver +- $a$ is the receiver acceptance angle (the angle between the lines at which the power detected by the receiver falls to $1/e^2$ ) + +If the curve of optical power density vs angle is known for the interfering transmitter, then the term $e^{\frac{-8\theta^2}{d^2}}$ in Equation 6-3 should be replaced by the (linear) value from the curve. + +Likewise, if the curve of optical power detected by the receiver vs angle is known, then the term $e^{\frac{-8\phi^2}{a^2}}$ in Equation 6-3 should be replaced by the (linear) value from the curve. + +## 6.2 Effect of the weather on crosstalk ratio + +Practical FSO systems are typically designed to be able to accommodate a wide variety of weather conditions. The two main effects due to the weather that must be taken into consideration in the calculation of crosstalk ratio are attenuation and beam divergence. + +### 6.2.1 Attenuation change + +In applying Equation 6-3 to calculate crosstalk ratio, care must be taken in the evaluation of the factor $\frac{O_I}{O_W}$ to ensure that the value used is the worst that can occur for any weather conditions that + +the wanted link must tolerate. Specifically, in the case where the interfering transmitter is closer to the receiver than the wanted transmitter, the worst-case ratio between the interfering power density and the wanted power density at the centre of their respective beams will be when the attenuation of the wanted link is at its maximum (i.e., in the worst weather conditions that it is required to tolerate). For an example of this, see Example 3 in Appendix I. + +### 6.2.2 Beam divergence change + +A second effect of the weather on FSO links is that the effective beam divergence may increase somewhat due to some adverse weather conditions. This effect should be taken into account in setting the value of $d$ used in Equation 6-3 to calculate the crosstalk ratio. + +In the case where the two co-located links operate at different wavelengths, the attenuation of the wanted and interfering beams due to the weather may be different. The degree of the attenuation difference, however, depends on a number of parameters such as the water droplet size. + +## 6.3 Case A – interference between two systems that can be at the same wavelength + +When the wavelengths of two co-located FSO systems can be the same, then to prevent mutual disturbance, each FSO system must claim some physical space. The space that they must claim is dependent on the level of interferometric crosstalk generated by the interferer. + +The interferometric crosstalk penalty from ITU-T G-series Recommendations – Supplement 39 (and including the effect of imperfect extinction ratio) is: + +$$P_I = 10 \log_{10} \left( \frac{\frac{r-1}{r+1}}{\frac{r-1}{r+1} + 10^{\frac{C_I}{10}} - 4 \sqrt{\frac{r}{r+1}} 10^{\frac{C_I}{10}}} \right) \quad [\text{dB}] \quad (6-4)$$ + +for an average power decision threshold, and: + +$$P_I = -10 \log_{10} \left( 1 - 2 \left( \frac{(1 + \sqrt{r}) \sqrt{10^{\frac{C_I}{10}} (r + 1)}}{r - 1} \right) \right) \quad [\text{dB}] \quad (6-5)$$ + +for an optimized decision threshold. + +where: + +$P_I$ is the interferometric crosstalk penalty (dB) + +$C_I = \log_{10}(C)$ is the interferometric crosstalk (dB) i.e., the ratio of the disturbing power to the wanted power detected by the receiver + +$r$ is the linear extinction ratio of the wanted signal + +The interferometric crosstalk penalty for an ideal wanted signal and one with 6 dB extinction ratio is plotted in Figure 6-9. + +![Figure 6-9/G.640 – Graph of optical penalty vs interferometric crosstalk for a single interferer (bounded model). The graph plots Optical penalty P_i (dB) on the y-axis (0 to 3) against Interferometric crosstalk C_i (dB) on the x-axis (-40 to -15). Four curves are shown: a black curve for '6 dB extinction ratio (r ≈ 4) on wanted signal', a red curve for 'Average power decision threshold', a blue curve for 'Optimum decision threshold', and a green curve for 'Ideal wanted signal'. The curves show that optical penalty increases with crosstalk and is highest for the 6 dB extinction ratio case and lowest for the ideal wanted signal case.](af06598cfb31b517e79b50d74f72a0ca_img.jpg) + +Figure 6-9/G.640 – Graph of optical penalty vs interferometric crosstalk for a single interferer (bounded model). The graph plots Optical penalty P\_i (dB) on the y-axis (0 to 3) against Interferometric crosstalk C\_i (dB) on the x-axis (-40 to -15). Four curves are shown: a black curve for '6 dB extinction ratio (r ≈ 4) on wanted signal', a red curve for 'Average power decision threshold', a blue curve for 'Optimum decision threshold', and a green curve for 'Ideal wanted signal'. The curves show that optical penalty increases with crosstalk and is highest for the 6 dB extinction ratio case and lowest for the ideal wanted signal case. + +**Figure 6-9/G.640 – Graph of optical penalty vs interferometric crosstalk for a single interferer (bounded model)** + +## 6.4 Case B – interference between two systems which cannot be at the same wavelength + +When the wavelengths of two co-located FSO systems **cannot** be the same (as illustrated in Figure 6-1 Case B) then the crosstalk generated by the interferer is inter-channel crosstalk. + +The inter-channel crosstalk penalty from ITU-T G-series Recommendations – Supplement 39 (and including the effect of imperfect extinction ratio) is: + +$$P_C = 10 \log_{10} \left( 1 - 10^{\frac{C_C}{10}} \frac{r+1}{r-1} \right) \quad [\text{dB}] \quad (6-6)$$ + +where: + +$P_C$ is the inter-channel crosstalk penalty (dB) + +$C_C = \log_{10}(C)$ is the inter-channel crosstalk (dB), i.e., the ratio of the disturbing power to the wanted power detected by the receiver + +$r$ is the linear extinction ratio of the wanted signal. + +The inter-channel crosstalk penalty for an ideal wanted signal, and one with 6 dB extinction ratio, is plotted in Figure 6-10. + +![Figure 6-10/G.640 – Graph of optical penalty vs inter-channel crosstalk for a single interferer. The graph shows two curves: a green curve for 'single interferer 6 dB extinction ratio (r = 3.98) on wanted signal' and a blue curve for 'Single interferer Ideal wanted signal'. The x-axis is 'Inter-channel crosstalk C_c dB' from -20 to 0. The y-axis is 'Optical penalty P_c dB' from 0 to 3. The green curve is above the blue curve, indicating a higher optical penalty for the same crosstalk level when the wanted signal has a 6 dB extinction ratio.](8ccbc9fa77bf60ba0ca0b79dec8681b8_img.jpg) + +| Inter-channel crosstalk $C_c$ (dB) | Optical penalty $P_c$ (dB) - Ideal wanted signal (Blue) | Optical penalty $P_c$ (dB) - 6 dB extinction ratio (Green) | +|------------------------------------|---------------------------------------------------------|------------------------------------------------------------| +| -20 | 0.1 | 0.1 | +| -18 | 0.15 | 0.2 | +| -16 | 0.2 | 0.3 | +| -14 | 0.3 | 0.5 | +| -12 | 0.4 | 0.8 | +| -10 | 0.6 | 1.2 | +| -8 | 1.0 | 2.0 | +| -6 | 1.5 | > 3.0 | + +Figure 6-10/G.640 – Graph of optical penalty vs inter-channel crosstalk for a single interferer. The graph shows two curves: a green curve for 'single interferer 6 dB extinction ratio (r = 3.98) on wanted signal' and a blue curve for 'Single interferer Ideal wanted signal'. The x-axis is 'Inter-channel crosstalk C\_c dB' from -20 to 0. The y-axis is 'Optical penalty P\_c dB' from 0 to 3. The green curve is above the blue curve, indicating a higher optical penalty for the same crosstalk level when the wanted signal has a 6 dB extinction ratio. + +**Figure 6-10/G.640 – Graph of optical penalty vs inter-channel crosstalk for a single interferer** + +## 6.5 Procedure for establishing whether the conditions for co-location longitudinal compatibility are met + +When it is required to site two FSO systems in close proximity to each other, the following procedure allows an assessment to be made as to whether the two systems will produce unacceptable interference with each other. The procedure must be completed twice for each pair of FSO systems, once with one system as the wanted and the other as interferer and then again with the roles reversed. + +- 1) Establish the optical penalty due to crosstalk that is allowed for in the power budget of the wanted system. For example this might be 0.5 dB. +- 2) Determine which of the two cases illustrated in Figure 6-1 applies. If there is a gap between the possible wavelength ranges of the two transmitters of at least the equivalent of the receiver electrical bandwidth then it is Case B and the crosstalk is inter-channel, otherwise it is Case A – interferometric crosstalk. +- 3) Calculate the crosstalk ratio. This is different depending upon the result of step 2. + - a) Case A. For interferometric crosstalk, use Equation 6-4 or 6-5 (depending on whether the receiver decision point is optimized or not) to calculate what value of crosstalk would generate the maximum penalty found in step 1. For example, a wanted transmitter with 6 dB extinction ratio, and a receiver with an average power decision threshold, will have a 0.5 dB penalty for a $C_I$ of approximately –35 dB (see Figure 6-9). + - b) Case B. For inter-channel crosstalk, use Equation 6-6 to calculate what value of crosstalk would generate the maximum penalty found in step 1. For example, a wanted transmitter with 6 dB extinction ratio will have a 0.5 dB penalty for a $C_C$ of approximately –12 dB (see Figure 6-10). + +- 4) Using Equation 6-3 and values for the physical parameters of the two FSO systems, calculate whether the physical locations proposed for the two systems will allow the maximum crosstalk levels found in step 3 to be met under all conditions. The information provided in 6.2 should be taken into account to make sure that the parameter values used correspond to the worst case that may be encountered for any weather conditions under which the wanted system is expected to operate satisfactorily. + +Examples of the use of this procedure in practical FSO systems can be found in Appendix I. + +# 7 Optical safety considerations + +Information on optical safety considerations relevant to FSO systems can be found in IEC 60825-1, IEC 60825-2 and IEC 60825-12. + +IEC 60825-12, *Safety of free space optical communication systems used for transmission of information*, in particular, gives details of the classification of locations where FSO systems might be operated and specifies the requirements on equipment operated in each of them. + +# Appendix I + +## Example crosstalk calculations + +### I.1 Example 1 + +Two FSO systems of the same design are needed to be installed between the same pair of buildings resulting in two parallel free space links. The characteristics of the individual systems are: + +- Distance between transmitter and receiver 400 m. +- Overall transmitted power maximum 8 mW and minimum 5 mW. +- Maximum transmitter beam divergence under worst weather conditions (d) 4 mrad. +- Transmitter minimum extinction ratio 8.2 dB. +- Maximum receiver acceptance angle (a) 5 mrad. +- Receiver has an average power decision threshold. +- Transmitter and receiver setting accuracy 1 mrad. +- Maximum crosstalk penalty 0.5 dB. + +What is the minimum separation of the two systems? A reference diagram for this example is shown in Figure I.1. + +![Figure I.1/G.640 – Example 1 crosstalk reference diagram. The diagram shows two transmitters (Tx) on the left and two receivers (Rx) on the right, separated by a distance of 400 m. The top Tx is labeled 'Wanted Tx' and the bottom Tx is labeled 'Interfering Tx'. The top Rx is labeled 'Rx' and the bottom Rx is also labeled 'Rx'. The vertical separation between the Tx and Rx pairs is labeled 'X'. The diagram illustrates crosstalk from the interfering Tx to the wanted Rx. The wanted Rx has an optical power level labeled 'O_w' and the interfering Rx has an optical power level labeled 'O_l'. The diagram also shows 'Rx setting error' and 'Tx setting error' as angular deviations. The angles are labeled 'a', 'φ', 'θ', and 'd'. The diagram is labeled 'G.640_F1.1' at the bottom right.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +Figure I.1/G.640 – Example 1 crosstalk reference diagram. The diagram shows two transmitters (Tx) on the left and two receivers (Rx) on the right, separated by a distance of 400 m. The top Tx is labeled 'Wanted Tx' and the bottom Tx is labeled 'Interfering Tx'. The top Rx is labeled 'Rx' and the bottom Rx is also labeled 'Rx'. The vertical separation between the Tx and Rx pairs is labeled 'X'. The diagram illustrates crosstalk from the interfering Tx to the wanted Rx. The wanted Rx has an optical power level labeled 'O\_w' and the interfering Rx has an optical power level labeled 'O\_l'. The diagram also shows 'Rx setting error' and 'Tx setting error' as angular deviations. The angles are labeled 'a', 'φ', 'θ', and 'd'. The diagram is labeled 'G.640\_F1.1' at the bottom right. + +**Figure I.1/G.640 – Example 1 crosstalk reference diagram** + +Following the procedure in 6.5 gives: + +- 1) The maximum optical penalty due to crosstalk is 0.5 dB. +- 2) Because the two systems are the same design, the wavelengths can be the same so it is case A – interferometric crosstalk. +- 3) Calculate the crosstalk ratio for case A. + - a) Case A. For interferometric crosstalk with an average power decision threshold, use Equation 6-4 to calculate that $C_I = -33.3$ dB would generate a 0.5 dB penalty with an extinction ratio of 8.2 dB. In linear terms this is $C_I = 0.000463$ . +- 4) Because, in this example, the links are parallel and the setting errors for the transmitter and receiver are the same, the angles $\theta$ and $\phi$ are the same for all values of separation $X$ . Because the two links are the same length, the ratio of $O_l$ to $O_w$ is the same as the ratio of the maximum to minimum transmitted power (since the interfering transmitter could be at the maximum power and the wanted transmitter at the minimum). Also, because the wavelengths are the same, $L = 1$ . Equation 6-3 therefore becomes: + +$$0.000463 = \frac{8}{5} e^{\frac{-80^2}{4^2}} e^{\frac{-80^2}{5^2}}$$ + +This equation is satisfied when $\theta$ (and therefore $\phi$ ) is 3.06 mrad. + +From the geometry of the links: + +$$\tan\left(\frac{1 + 3.06}{1000}\right) = \frac{X}{200}$$ + +which is satisfied for a separation $X = 1.6$ m. + +### I.2 Example 2 + +This example is the same as example 1 except that the worst-case characteristics of the transmitter beam are known to be inside the curve in Figure I.2, and the worst-case values of the optical power detected by the receiver vs angle are inside the curve in Figure I.3. + +![Figure I.2/G.640: Worst-case curve of power density vs angle for the transmitters. The graph shows Relative power (dB) on the y-axis (from -40 to 0) versus Angle from axis θ (mrad) on the x-axis (from -6 to 6). A solid black curve is shown, which is flat at 0 dB between -2 and 2 mrad. It has a linear decrease from 0 dB at -2 mrad to -40 dB at -5 mrad, and a linear increase from 0 dB at 2 mrad to -40 dB at 5 mrad. A horizontal dashed red line is drawn at -9 dB, labeled with the fraction 1/e² on the right. The curve intersects this dashed line at approximately ±3.2 mrad. The label G.640_Fl.2 is at the bottom right.](2a77eb32ef4c4d8a5c1758a53a908336_img.jpg) + +Figure I.2/G.640: Worst-case curve of power density vs angle for the transmitters. The graph shows Relative power (dB) on the y-axis (from -40 to 0) versus Angle from axis θ (mrad) on the x-axis (from -6 to 6). A solid black curve is shown, which is flat at 0 dB between -2 and 2 mrad. It has a linear decrease from 0 dB at -2 mrad to -40 dB at -5 mrad, and a linear increase from 0 dB at 2 mrad to -40 dB at 5 mrad. A horizontal dashed red line is drawn at -9 dB, labeled with the fraction 1/e² on the right. The curve intersects this dashed line at approximately ±3.2 mrad. The label G.640\_Fl.2 is at the bottom right. + +**Figure I.2/G.640 – Worst-case curve of power density vs angle for the transmitters** + +![Figure I.3/G.640: Worst-case curve of optical power detected by the receiver vs angle. The graph shows Relative received power (dB) on the y-axis (from -40 to 0) versus Angle from axis φ (mrad) on the x-axis (from -6 to 6). A solid black curve is shown, which is flat at 0 dB between -1.5 and 1.5 mrad. It has a linear decrease from 0 dB at -1.5 mrad to -40 dB at -5 mrad, and a linear increase from 0 dB at 1.5 mrad to -40 dB at 5 mrad. A horizontal dashed red line is drawn at -9 dB, labeled with the fraction 1/e² on the right. The curve intersects this dashed line at approximately ±3.5 mrad. The label G.640_Fl.3 is at the bottom right.](79cb7fa0e9c78ec5cd0b0de977824f8d_img.jpg) + +Figure I.3/G.640: Worst-case curve of optical power detected by the receiver vs angle. The graph shows Relative received power (dB) on the y-axis (from -40 to 0) versus Angle from axis φ (mrad) on the x-axis (from -6 to 6). A solid black curve is shown, which is flat at 0 dB between -1.5 and 1.5 mrad. It has a linear decrease from 0 dB at -1.5 mrad to -40 dB at -5 mrad, and a linear increase from 0 dB at 1.5 mrad to -40 dB at 5 mrad. A horizontal dashed red line is drawn at -9 dB, labeled with the fraction 1/e² on the right. The curve intersects this dashed line at approximately ±3.5 mrad. The label G.640\_Fl.3 is at the bottom right. + +**Figure I.3/G.640 – Worst-case curve of optical power detected by the receiver vs angle** + +The procedure for this example is identical to that of example 1, up to step 4. Now Equation 6-3 becomes: + +$$0.000463 = \frac{8}{5} \text{ (value from Figure I.2} \times \text{value from Figure I.3)}$$ + +This equation is satisfied when $\theta$ (and therefore $\phi$ ) is 3.82 mrad. + +From the geometry of the links: + +$$\tan\left(\frac{1+3.82}{1000}\right) = \frac{X}{200}$$ + +which is satisfied for a separation $X = 1.9$ m. + +### I.3 Example 3 + +Two FSO systems of the same design are needed to be installed in the arrangement shown in Figure I.4. + +![Diagram of Example 3 configuration showing two FSO links. Link 1 is a horizontal line between Tx 1 and Rx 1, labeled 'Link 1 400 m'. Link 2 is a diagonal line between Tx 2 and Rx 2, labeled 'Link 2 300 m'. Tx 1 and Tx 2 are on the left, and Rx 1 and Rx 2 are on the right. A vertical line on the left indicates a height of 2 m from the ground to Tx 1. A vertical line on the right indicates a height of 1.2 m from the ground to Rx 1. The ground is represented by a dashed line. The diagram is labeled G.640_F1.4 in the bottom right corner.](7d3d5fb5d09c0cd35a9d637be241651e_img.jpg) + +The diagram illustrates the configuration for Example 3. It shows two FSO links. Link 1 is a horizontal line between transmitter Tx 1 and receiver Rx 1, with a distance of 400 m. Link 2 is a diagonal line between transmitter Tx 2 and receiver Rx 2, with a distance of 300 m. Tx 1 and Tx 2 are on the left, and Rx 1 and Rx 2 are on the right. A vertical line on the left indicates a height of 2 m from the ground to Tx 1. A vertical line on the right indicates a height of 1.2 m from the ground to Rx 1. The ground is represented by a dashed line. The diagram is labeled G.640\_F1.4 in the bottom right corner. + +Diagram of Example 3 configuration showing two FSO links. Link 1 is a horizontal line between Tx 1 and Rx 1, labeled 'Link 1 400 m'. Link 2 is a diagonal line between Tx 2 and Rx 2, labeled 'Link 2 300 m'. Tx 1 and Tx 2 are on the left, and Rx 1 and Rx 2 are on the right. A vertical line on the left indicates a height of 2 m from the ground to Tx 1. A vertical line on the right indicates a height of 1.2 m from the ground to Rx 1. The ground is represented by a dashed line. The diagram is labeled G.640\_F1.4 in the bottom right corner. + +**Figure I.4/G.640 – Example 3 configuration** + +The characteristics of the two systems are: + +- Overall transmitted power maximum 8 mW and minimum 5 mW. +- Maximum transmitter beam divergence under worst weather conditions (d) 4 mrad. +- Transmitter minimum extinction ratio 10 dB. +- Maximum receiver acceptance angle (a) 6 mrad. +- Receiver has an average power decision threshold. +- Transmitter and receiver setting accuracy 1 mrad. +- Maximum crosstalk penalty 0.5 dB. +- Link 1, distance between transmitter and receiver 400 m. +- Allocation in Link 1 budget for atmospheric attenuation 25 dB. +- Link 2, distance between transmitter and receiver 300 m. + +Will the crosstalk penalty be acceptable for both systems? + +A reference diagram with link 1 as the wanted system is shown in Figure I.5. + +![Figure I.5/G.640 – Example 3 crosstalk reference diagram for link 1. The diagram shows two transmitters, Wanted Tx 1 and Interfering Tx 2, and two receivers, Rx 1 and Rx 2. Tx 1 is connected to Rx 1 via a solid line, and Tx 2 is connected to Rx 2 via a solid line. Dashed lines represent crosstalk paths from Tx 1 to Rx 2 and from Tx 2 to Rx 1. Angles are labeled: alpha (α) for the main beam divergence at Rx 1, phi (φ) for the angle from Tx 2 to Rx 1, theta (θ) for the angle from Tx 1 to Rx 2, and d for the distance between the main beams. Labels include 'Rx setting error' and 'Tx setting error'.](365b54f616aff249b4e6c0edafdcb9b3_img.jpg) + +Figure I.5/G.640 – Example 3 crosstalk reference diagram for link 1. The diagram shows two transmitters, Wanted Tx 1 and Interfering Tx 2, and two receivers, Rx 1 and Rx 2. Tx 1 is connected to Rx 1 via a solid line, and Tx 2 is connected to Rx 2 via a solid line. Dashed lines represent crosstalk paths from Tx 1 to Rx 2 and from Tx 2 to Rx 1. Angles are labeled: alpha (α) for the main beam divergence at Rx 1, phi (φ) for the angle from Tx 2 to Rx 1, theta (θ) for the angle from Tx 1 to Rx 2, and d for the distance between the main beams. Labels include 'Rx setting error' and 'Tx setting error'. + +**Figure I.5/G.640 – Example 3 crosstalk reference diagram for link 1** + +Following the procedure in 6.5 for Tx 1 as the wanted transmitter and Tx 2 as the interferer gives: + +- 1) The maximum optical penalty due to crosstalk is 0.5 dB. +- 2) Because the two systems are the same design, the wavelengths can be the same so it is Case A – interferometric crosstalk. +- 3) Calculate the crosstalk ratio for Case A. + - a) Case A. For interferometric crosstalk with an average power decision threshold use Equation 6-4 to calculate that $C_I = -32.6$ dB would generate 0.5 dB penalty with an extinction ratio of 10 dB. In linear terms this is $C_I = 0.000545$ . +- 4) From the geometry defined in Figure I.4, the angle $\phi \approx 1000 \times \arctan(2/300) - 1$ mrad which is 5.67 mrad, and the angle $\theta \approx 1000 \times \arctan(1.2/300) - 1$ mrad which is 3.0 mrad. Because link 2 is shorter than link 1, the ratio of $O_I$ to $O_W$ depends on the square of the link distances, the weather conditions, and the ratio of the maximum to minimum transmitted power (since the interfering transmitter could be at the maximum power and the wanted transmitter at the minimum power). This ratio is therefore: + +$$\frac{O_I}{O_W} = \frac{8 \cdot 400^2}{5 \cdot 300^2} 10^{\frac{\left(25 - 25 \frac{300}{400}\right)}{10}} = 12$$ + +with the last term taking account of the atmospheric attenuation in link 2 in conditions where there is 25 dB of attenuation in link 1. Because the wavelengths can be the same, $L = 1$ . Equation 6-3 therefore becomes: + +$$C = 12 e^{-\frac{8 \times 3.0^2}{4^2}} e^{-\frac{8 \times 5.67^2}{6^2}} = 0.0000106 = -39.7 \text{ dB}$$ + +Since this level of crosstalk is below the value of $-32.6$ dB, which is the maximum the receiver can tolerate, the proposed geometry of the links is acceptable to link 1. + +A reference diagram with link 2 as the wanted system is shown in Figure I.6. + +![Figure I.6/G.640 – Example 3 crosstalk reference diagram for link 2. The diagram shows two transmitters, Interfering Tx 1 and Wanted Tx 2, and two receivers, Rx 1 and Rx 2. Tx 1 is at the top left, Tx 2 is at the bottom left. Rx 1 is at the top right, Rx 2 is at the bottom right. Green dashed lines represent the signal from Tx 1 to Rx 1, with an angle 'd' at Tx 1 and an arrow pointing to the line labeled 'Tx setting error'. Red dashed lines represent the signal from Tx 1 to Rx 2, with an angle 'θ' at Tx 1. Black dashed lines represent the signal from Tx 2 to Rx 2, with an angle 'φ' at Tx 2 and an arrow pointing to the line labeled 'Rx setting error'. Blue dashed lines represent the signal from Tx 2 to Rx 1, with an angle 'a' at Rx 2. The diagram is labeled 'G.640_F1.6' at the bottom right.](73b5cce955ba9415a98791db7b0080ad_img.jpg) + +Figure I.6/G.640 – Example 3 crosstalk reference diagram for link 2. The diagram shows two transmitters, Interfering Tx 1 and Wanted Tx 2, and two receivers, Rx 1 and Rx 2. Tx 1 is at the top left, Tx 2 is at the bottom left. Rx 1 is at the top right, Rx 2 is at the bottom right. Green dashed lines represent the signal from Tx 1 to Rx 1, with an angle 'd' at Tx 1 and an arrow pointing to the line labeled 'Tx setting error'. Red dashed lines represent the signal from Tx 1 to Rx 2, with an angle 'θ' at Tx 1. Black dashed lines represent the signal from Tx 2 to Rx 2, with an angle 'φ' at Tx 2 and an arrow pointing to the line labeled 'Rx setting error'. Blue dashed lines represent the signal from Tx 2 to Rx 1, with an angle 'a' at Rx 2. The diagram is labeled 'G.640\_F1.6' at the bottom right. + +**Figure I.6/G.640 – Example 3 crosstalk reference diagram for link 2** + +Following the procedure in 6.5 for Tx 2 as the wanted transmitter and Tx 1 as the interferer gives: + +- 1) The maximum optical penalty due to crosstalk is 0.5 dB. +- 2) Because the two systems are the same design, the wavelengths can be the same so it is Case A – interferometric crosstalk. +- 3) Calculate the crosstalk ratio for Case A. + - a) Case A. For interferometric crosstalk with an average power decision threshold, use Equation 6-4 to calculate that $C_I = -32.6$ dB would generate a 0.5 dB penalty with an extinction ratio of 10 dB. In linear terms this is $C_I = 0.000545$ . +- 4) From the geometry defined in Figure I.4 the angle $\varphi \approx 1000 \times (\arctan(0.8/300) + \arctan(1.2/400)) - 1$ mrad which is 4.67 mrad, and the angle $\theta \approx 1000 \times \arctan(1.2/400) - 1$ mrad which is 2.0 mrad. + +Because link 2 is shorter than link 1, the ratio of $P_I$ to $P_W$ depends on the square of the link distances, the weather conditions, and the ratio of the maximum to minimum transmitted power (since the interfering transmitter could be at the maximum power and the wanted transmitter at the minimum). The crosstalk will be worst for clear conditions, so the worst ratio is therefore: + +$$\frac{P_I}{P_W} = \frac{8\,300^2}{5\,400^2} = 0.9$$ + +Because the wavelengths can be the same, $L = 1$ . Equation 6-3 therefore becomes: + +$$C = 0.9 e^{-\frac{8 \times 2.0^2}{4^2}} e^{-\frac{8 \times 4.67^2}{6^2}} = 0.000964 = -30.2 \text{ dB}$$ + +Since this level of crosstalk is above the value of $-32.6$ dB, which is the maximum the receiver can tolerate, the proposed geometry of the links must be changed in order to avoid link 1 exceeding its maximum crosstalk penalty. This can be achieved by increasing the separation of the receivers to at least 1.4 m. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.656-201007-I_PDF-E/raw.md b/marked/G/T-REC-G.656-201007-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..8e064beb2101421198a64caca0502190761fb24d --- /dev/null +++ b/marked/G/T-REC-G.656-201007-I_PDF-E/raw.md @@ -0,0 +1,529 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.656** + +(07/2010) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Transmission media and optical systems characteristics – +Optical fibre cables + +# --- **Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport** + +Recommendation ITU-T G.656 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| General | G.600–G.609 | +| Symmetric cable pairs | G.610–G.619 | +| Land coaxial cable pairs | G.620–G.629 | +| Submarine cables | G.630–G.639 | +| Free space optical systems | G.640–G.649 | +| Optical fibre cables | G.650–G.659 | +| Characteristics of optical components and subsystems | G.660–G.679 | +| Characteristics of optical systems | G.680–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.656 + +# Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport + +## Summary + +Recommendation ITU-T G.656 describes the geometrical, mechanical, and transmission attributes of a single-mode optical fibre which has the positive value of the chromatic dispersion coefficient greater than some non-zero value throughout the wavelength range of anticipated use 1460-1625 nm. This dispersion reduces the growth of non-linear effects which are particularly deleterious in dense wavelength division multiplexing systems. + +This fibre can be used for both CWDM (coarse wavelength division multiplexing) and DWDM (dense wavelength division multiplexing) systems throughout the wavelength region between 1460 and 1625 nm. + +Edition 2 limits the chromatic dispersion coefficient by a pair of bounding curves vs wavelength for the range of 1460 nm to 1625 nm, which provides information to support CWDM and DWDM applications. + +Edition 3 removes jumper cut-off wavelength definition and adds a note allowing higher maximum cabled attenuation for short jumper cables. + +## History + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.656 | 2004-06-13 | 15 | +| 2.0 | ITU-T G.656 | 2006-12-14 | 15 | +| 3.0 | ITU-T G.656 | 2010-07-29 | 15 | + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2011 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +| | Page | +|----------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 4 Abbreviations..... | 2 | +| 5 Fibre attributes ..... | 2 | +| 5.1 Mode field diameter ..... | 2 | +| 5.2 Cladding diameter ..... | 2 | +| 5.3 Core concentricity error..... | 2 | +| 5.4 Non-circularity ..... | 3 | +| 5.5 Cut-off wavelength..... | 3 | +| 5.6 Macrobending loss..... | 3 | +| 5.7 Material properties of the fibre..... | 4 | +| 5.8 Refractive index profile..... | 4 | +| 5.9 Longitudinal uniformity of chromatic dispersion..... | 4 | +| 5.10 Chromatic dispersion coefficient..... | 4 | +| 6 Cable attributes ..... | 5 | +| 6.1 Attenuation coefficient ..... | 5 | +| 6.2 Polarization mode dispersion (PMD) coefficient..... | 5 | +| 7 Table of recommended values ..... | 6 | +| Appendix I – Information for link attributes and system design ..... | 8 | +| I.1 Attenuation ..... | 8 | +| I.2 Chromatic dispersion..... | 8 | +| I.3 Differential group delay (DGD) ..... | 9 | +| I.4 Non-linear coefficient..... | 9 | +| I.5 Tables of common typical values ..... | 10 | +| I.6 Chromatic dispersion coefficient limits..... | 10 | +| Bibliography..... | 12 | + + + +## Recommendation ITU-T G.656 + +# Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport + +# 1 Scope + +This Recommendation describes a single-mode fibre with chromatic dispersion that is greater than some non-zero value throughout the wavelength range of 1460-1625 nm. This dispersion reduces the growth of non-linear effects that can be particularly deleterious in dense wavelength division multiplexing (DWDM) systems. This fibre uses non-zero dispersion to reduce four-wave mixing and cross-phase modulation over a wider wavelength range than the fibre described in [b-ITU-T G.655]. Extensions are possible, in the future, to wavelengths beyond the 1460-1625 nm region (to be determined). The geometrical, optical, transmission, and mechanical parameters are described below in three categories of attributes: + +- fibre attributes are those attributes that are retained throughout cabling and installation; +- cable attributes that are recommended for cables as they are delivered; +- link attributes that are characteristics of concatenated cables, describing estimation methods of system interface parameters based on measurements, modelling, or other considerations. Information for link attributes and system design are given in Appendix I. + +This fibre can be utilized for CWDM and DWDM systems throughout the extended wavelength transmission region between 1460 and 1625 nm. + +This Recommendation, and the category found in the table of clause 7, is intended to support the following related system Recommendations: + +- [b-ITU-T G.691]; +- [b-ITU-T G.692]; +- [b-ITU-T G.693]; +- [b-ITU-T G.695]; +- [b-ITU-T G.959.1]; +- [b-ITU-T G.698.1]; +- [b-ITU-T G.696.1]. + +The meaning of the terms used in this Recommendation and the guidelines to be followed in the measurement to verify the various characteristics are given in [ITU-T G.650.1] and [ITU-T G.650.2]. The characteristics of this fibre, including the definitions of the relevant parameters, their test methods and relevant values, will be refined as studies and experience progress. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.650.1] Recommendation ITU-T G.650.1 (2010), *Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable.* +- [ITU-T G.650.2] Recommendation ITU-T G.650.2 (2007), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable.* +- [ITU-T G.694.1] Recommendation ITU-T G.694.1 (2002), *Spectral grids for WDM applications: DWDM frequency grid.* + +# 3 Definitions + +For the purposes of this Recommendation, the definitions given in [ITU-T G.650.1] and [ITU-T G.650.2] apply. Values shall be rounded to the number of digits given in the table of Recommended values before conformance is evaluated. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------------------|-----------------------------------------| +| $A_{\text{eff}}$ | Effective Area | +| CWDM | Coarse Wavelength Division Multiplexing | +| DGD | Differential Group Delay | +| DWDM | Dense Wavelength Division Multiplexing | +| PMD | Polarization Mode Dispersion | +| PMD Q | Statistical parameter for PMD link | +| SDH | Synchronous Digital Hierarchy | +| TBD | To Be Determined | + +# 5 Fibre attributes + +Only those characteristics of the fibre providing a minimum essential design framework for fibre manufacturers are recommended in this clause. Ranges or limits on values are presented in the table of clause 7. Of these, cable manufacture or installation may significantly affect the cabled fibre cut-off wavelength and PMD. Otherwise, the recommended characteristics will apply equally to individual fibres, fibres incorporated into a cable wound on a drum, and fibres in an installed cable. + +## 5.1 Mode field diameter + +Both a nominal value and tolerance about that nominal value shall be specified at 1550 nm. The nominal value that is specified shall be within the range found in clause 7. The specified tolerance shall not exceed the value in clause 7. The deviation from nominal shall not exceed the specified tolerance. + +## 5.2 Cladding diameter + +The recommended nominal value of the cladding diameter is 125 µm. A tolerance is also specified and shall not exceed the value in clause 7. The cladding deviation from nominal shall not exceed the specified tolerance. + +## 5.3 Core concentricity error + +The core concentricity error shall not exceed the value specified in clause 7. + +## 5.4 Non-circularity + +#### 5.4.1 Mode field non-circularity + +In practice, the mode field non-circularity of fibres having nominally circular mode fields is found to be sufficiently low that propagation and jointing are not affected. It is, therefore, not considered necessary to recommend a particular value for the mode field non-circularity. It is not normally necessary to measure the mode field non-circularity for acceptance purposes. + +#### 5.4.2 Cladding non-circularity + +The cladding non-circularity shall not exceed the value found in clause 7. + +## 5.5 Cut-off wavelength + +Two useful types of cut-off wavelength can be distinguished: + +- a) Cable cut-off wavelength, $\lambda_{cc}$ . +- b) Fibre cut-off wavelength, $\lambda_c$ . + +NOTE – For some specific submarine cable applications, other cable cut-off wavelength values may be required. + +The correlation of the measured values of $\lambda_c$ and $\lambda_{cc}$ depends on the specific fibre and cable design and the test conditions. While in general, $\lambda_{cc} < \lambda_c$ , a general quantitative relationship cannot be easily established. The importance of ensuring single-mode transmission in the minimum cable length between joints at the minimum operating wavelength is paramount. This may be performed by recommending the maximum cable cut-off wavelength $\lambda_{cc}$ of a cabled single-mode fibre to be 1450 nm, or for worst-case length and bends, by recommending a maximum fibre cut-off wavelength to be 1440 nm. + +The cable cut-off wavelength, $\lambda_{cc}$ , shall be less than the maximum specified in clause 7. + +## 5.6 Macrobending loss + +Macrobending loss varies with wavelength, bend radius and number of turns about a mandrel with a specified radius. Macrobending loss shall not exceed the maximum given in clause 7 for the specified wavelength(s), bend radius, and number of turns. + +NOTE 1 – A qualification test may be sufficient to ensure that this requirement is being met. + +NOTE 2 – The recommended number of turns corresponds to the approximate number of turns deployed in all splice cases of a typical repeater span. The recommended radius is equivalent to the minimum bend-radius widely accepted for long-term deployment of fibres in practical systems installations to avoid static-fatigue failure. + +NOTE 3 – If, for practical reasons, fewer than the recommended number of turns are chosen to implement, it is suggested that not less than 40 turns, and a proportionately smaller loss increase be required. + +NOTE 4 – The macrobending loss recommendation relates to the deployment of fibres in practical single-mode fibre installations. The influence of the stranding-related bending radii of cabled single-mode fibres on the loss performance is included in the loss specification of the cabled fibre. + +NOTE 5 – In the event that routine tests are required, a smaller diameter loop with one or several turns can be used instead of the recommended test, for accuracy and measurement ease. In this case, the loop diameter, number of turns, and the maximum permissible bend loss for the several-turn test should be chosen so as to correlate with the recommended test and allowed loss. + +## 5.7 Material properties of the fibre + +#### 5.7.1 Fibre materials + +The substances of which the fibres are made should be indicated. + +NOTE – Care may be needed in fusion splicing fibres of different substances. Provisional results indicate that adequate splice loss and strength can be achieved when splicing different high-silica fibres. + +#### 5.7.2 Protective materials + +The physical and chemical properties of the material used for the fibre primary coating and the best way of removing it (if necessary) should be indicated. In the case of single jacketed fibre, similar indications shall be given. + +#### 5.7.3 Proofstress level + +The specified proofstress, $\sigma_p$ , shall not be less than the minimum specified in clause 7. + +NOTE – The definitions of the mechanical parameters are contained in clauses 3.2 and 5.7 of [ITU-T G.650.1]. + +## 5.8 Refractive index profile + +The refractive index profile of the fibre does not generally need to be known. + +## 5.9 Longitudinal uniformity of chromatic dispersion + +Under study. + +NOTE – At a particular wavelength, the local absolute value of the chromatic dispersion coefficient can vary away from the value measured on a long length. If the value decreases to a small value at a wavelength that is close to an operating wavelength in a DWDM system, four-wave mixing can induce the propagation of power at other wavelengths, including, but not limited to, other operating wavelengths. The magnitude of the four-wave mixing power is a function of the absolute value of the chromatic dispersion coefficient, the chromatic dispersion slope, the operating wavelengths, the optical power, and the distance over which four-wave mixing occurs. + +## 5.10 Chromatic dispersion coefficient + +The chromatic dispersion coefficient, $D$ , is specified with a wavelength range. [ITU-T G.650.1] provides measurement methods. There are two methods for specifying the limits, the original method, which is a box-like specification, and a newer method, in which the dispersion coefficient values are bound both by a pair of curves and by the value at 1550 nm. + +The measured group delay or chromatic dispersion per unit fibre length versus wavelength shall be fitted by either the 5-term Sellmeier equation or the 4th order polynomial equation as defined in Annex A of [ITU-T G.650.1]. (See clause 5.5 of [ITU-T G.650.1] for guidance on the interpolation of dispersion values to unmeasured wavelengths.) + +The fitted equation should not be used to predict chromatic dispersion at wavelength outside the range used for the fit. + +For each wavelength, $\lambda$ , the chromatic dispersion coefficient, $D(\lambda)$ , shall be restricted to a range of values associated with two limiting curves, $D_{\min}(\lambda)$ and $D_{\max}(\lambda)$ , for one or more specified wavelength ranges defined in terms of $\lambda_{\min}$ and $\lambda_{\max}$ . + +An example set of curves is represented symbolically as a pair of straight lines: + +$$D_{\min}(\lambda) = a_{\min} + b_{\min} (\lambda - 1460) \text{ [ps/nm} \cdot \text{km]}$$ + +$$D_{\max}(\lambda) = a_{\max} + b_{\max} (\lambda - 1460) \text{ [ps/nm} \cdot \text{km]}$$ + +$$D_{\min}(\lambda) \leq D(\lambda) \leq D_{\max}(\lambda) \text{ [ps/nm} \cdot \text{km]}$$ + +The bounding curves may vary from one wavelength range to another. + +NOTE 1 – Chromatic dispersion uniformity should be consistent with the functioning of the system. + +NOTE 2 – The requirements on chromatic dispersion follow from WDM system design, which must balance first order chromatic dispersion with various non-linear effects, such as four-wave mixing, cross-phase modulation, modulation instability, stimulated Brillouin scattering, and soliton formation (see [b-ITU-T G.663]). The effect of chromatic dispersion is interactive with the fibre non-linearity, described by the non-linear coefficient. + +NOTE 3 – It is not necessary to measure the chromatic dispersion coefficient on a routine basis. + +# **6 Cable attributes** + +Since the geometrical and optical characteristics of fibres given in clause 5 are barely affected by the cabling process, this clause will give recommendations mainly relevant to transmission characteristics of cabled factory lengths. Environmental and test conditions are paramount and are described in the guidelines for test methods. + +## **6.1 Attenuation coefficient** + +The attenuation coefficient is specified with a maximum value at one or more wavelengths in the 1460 nm, 1550 nm and 1625 nm regions. The optical fibre cable attenuation coefficient values shall not exceed the values found in clause 7. + +NOTE – The attenuation coefficient may be calculated across a spectrum of wavelengths, based on measurements at a few (3 to 4) predictor wavelengths. This procedure is described in clause 5.4.4 of [ITU-T G.650.1] and an example is given in Appendix III of [ITU-T G.650.1]. + +## **6.2 Polarization mode dispersion (PMD) coefficient** + +When required, cabled fibre polarization mode dispersion shall be specified on a statistical basis, not on an individual fibre basis. The requirements pertain only to the aspect of the link calculated from cable information. The metrics of the statistical specification are found below. Methods of calculations are found in [b-IEC/TR 61282-3], and are summarized in Appendix IV of [ITU-T G.650.2]. + +The manufacturer shall supply a PMD link design value, $\text{PMD}_Q$ , that serves as a statistical upper bound for the PMD coefficient of the concatenated optical fibre cables within a defined possible link of $M$ cable sections. The upper bound is defined in terms of a small probability level, $Q$ , which is the probability that a concatenated PMD coefficient value exceeds $\text{PMD}_Q$ . For the values of $M$ and $Q$ given in clause 7, the value of $\text{PMD}_Q$ shall not exceed the maximum PMD coefficient specified in clause 7. + +Measurements and specifications on uncabled fibre are necessary, but not sufficient to ensure the cabled fibre specification. The maximum link design value specified on uncabled fibre shall be less than or equal to that specified for the cabled fibre. The ratio of PMD values for uncabled fibre to cabled fibre depends on the details of the cable construction and processing, as well as on the mode coupling condition of the uncabled fibre. [ITU-T G.650.2] recommends a low mode coupling deployment requiring a low tension wrap on a large diameter spool for uncabled fibre PMD measurements. + +The limits on the distribution of PMD coefficient values can be interpreted as being nearly equivalent to limits on the statistical variation of the differential group delay (DGD), that varies randomly with time and wavelength. When the PMD coefficient distribution is specified for optical fibre cable, equivalent limits on the variation of DGD can be determined. The metrics and values for link DGD distribution limits are found in Appendix I. + +NOTE 1 – PMDQ specification would be required only where cables are employed for systems that have the specification of the max DGD, i.e., for example, PMDQ specification would not be applied to systems recommended in [b-ITU-T G.957]. + +NOTE 2 – PMDQ should be calculated for various types of cables, and they should usually be calculated using sampled PMD values. The samples would be taken from cables of similar construction. + +NOTE 3 – The PMDQ specification should not be applied to short cables such as jumper cables, indoor cables and drop cables. + +# 7 Table of recommended values + +Table 1 summarizes the recommended values for a category of fibres that satisfy the objectives of this Recommendation. + +Table 1, "ITU-T G.656 attributes", defines the chromatic dispersion coefficient requirements as a pair of bounding curves vs wavelength for wavelengths from 1460 nm to 1625 nm. This is also intended to support optical interface Recommendations such as [b-ITU-T G.691], [b-ITU-T G.692], [b-ITU-T G.959.1] and [b-ITU-T G.693]. + +For DWDM systems, channel spacings defined in [ITU-T G.694.1] are supported, depending on the minimum dispersion that is selected. The PMD requirement allows operation of STM-64 systems to lengths of up to 2000 km, depending on other system elements. + +**Table 1 – ITU-T G.656 attributes** + +| Fibre attributes | | | +|--------------------------------------------------------------|------------------------------------|------------------------------------------| +| Attribute | Detail | Value | +| Mode field diameter | Wavelength | 1550 nm | +| | Range of nominal values | 7.0-11.0 µm | +| | Tolerance | ±0.7 µm | +| Cladding diameter | Nominal | 125.0 µm | +| | Tolerance | ±1 µm | +| Core concentricity error | Maximum | 0.8 µm | +| Cladding non-circularity | Maximum | 2.0% | +| Cable cut-off wavelength | Maximum | 1450 nm | +| Macrobend loss | Radius | 30 mm | +| | Number of turns | 100 | +| | Maximum at 1625 nm | 0.50 dB | +| Proof stress | Minimum | 0.69 GPa | +| Chromatic dispersion coefficient
(ps/nm · km)
(Note 1) | $D_{\min}(\lambda)$ : 1460-1550 nm | $\frac{2.60}{90}(\lambda - 1460) + 1.00$ | +| | $D_{\min}(\lambda)$ : 1550-1625 nm | $\frac{0.98}{75}(\lambda - 1550) + 3.60$ | +| | $D_{\max}(\lambda)$ : 1460-1550 nm | $\frac{4.68}{90}(\lambda - 1460) + 4.60$ | +| | $D_{\max}(\lambda)$ : 1550-1625 nm | $\frac{4.72}{75}(\lambda - 1550) + 9.28$ | +| Uncabled fibre PMD coefficient | Maximum | (Note 2) | + +**Table 1 – ITU-T G.656 attributes** + +| Cable attributes | | | +|-------------------------------------|--------------------------|--------------| +| Attribute | Detail | Value | +| Attenuation coefficient
(Note 3) | Maximum at 1460 nm | 0.4 dB/km | +| | Maximum at 1550 nm | 0.35 dB/km | +| | Maximum at 1625 nm | 0.4 dB/km | +| PMD coefficient | M | 20 cables | +| | Q | 0.01% | +| | Maximum PMD Q | 0.20 ps/√km | + +NOTE 1 – If a Raman pump is used outside this wavelength region, fibre properties must be suitable for accommodating this pump. + +NOTE 2 – According to clause 6.2, a maximum PMDQ value on uncabled fibre is specified in order to support the primary requirement on cabled PMDQ. + +NOTE 3 – The attenuation coefficient values listed in this table should not be applied to short cables such as jumper cables. For example, [b-IEC 60794-2-11] specifies the attenuation coefficient of indoor cable as 1.0 dB/km or less at both 1310 and 1550 nm. + +# Appendix I + +## Information for link attributes and system design + +(This appendix does not form an integral part of this Recommendation) + +A concatenated link usually includes a number of spliced factory lengths of optical fibre cable. The requirements for factory lengths are given in clauses 5 and 6. The transmission parameters for concatenated links must take into account not only the performance of the individual cable lengths but also the statistics of concatenation. + +The transmission characteristics of the factory length optical fibre cables will have a certain probability distribution which often needs to be taken into account if the most economic designs are to be obtained. The following clauses should be read with this statistical nature of the various parameters in mind. + +Link attributes are affected by factors other than optical fibre cables by such things as splices, connectors, and installation. These factors cannot be specified in this Recommendation. For the purpose of link attribute values estimation, typical values of optical fibre links are provided in clause I.5. The estimation methods of parameters needed for system design are based on measurements, modelling, or other considerations. + +### I.1 Attenuation + +The attenuation, $A$ , of a link is given by: + +$$A = \alpha L + \alpha_s x + \alpha_c y \quad (\text{I-1})$$ + +where: + +$\alpha$ = typical attenuation coefficient of fibre cables in a link + +$\alpha_s$ = mean splice loss + +$x$ = number of splices in a link + +$\alpha_c$ = mean loss of line connectors + +$y$ = number of line connectors in a link (if provided) + +$L$ = length of a link + +A suitable margin should be allocated for future modifications of cable configurations (additional splices, extra cable lengths, ageing effects, temperature variations, etc.). Equation I-1 does not include the loss of equipment connectors. The typical values found in clause I.5 are for the attenuation coefficient of optical fibre link. The attenuation budget used in designing an actual system should account for the statistical variations in these parameters. + +### I.2 Chromatic dispersion + +The chromatic dispersion in ps/nm can be calculated from the chromatic dispersion coefficients of the factory lengths, assuming a linear dependence on length, and with due regard for the signs of the coefficients (see clause 5.10). + +When these fibres are used for transmission in the 1550 nm region, chromatic dispersion accommodation is sometimes employed. In this case, the average link chromatic dispersion is used for design. + +For simplified estimation, the relationship is described in terms of the typical chromatic dispersion coefficient and chromatic dispersion slope coefficient at 1550 nm. + +Typical values for the chromatic dispersion coefficient, $D_{1550}$ , and chromatic dispersion slope coefficient, $S_{1550}$ , at 1550 nm vary with the specific implementation. These values, together with link length, $L_{Link}$ , can be used to calculate the typical dispersion for use in optical link design. + +$$D_{Link}(\lambda) = L_{Link} [D_{1550} + S_{1550}(\lambda - 1550)] \quad (\text{ps/nm}) \quad (\text{I-2})$$ + +For estimation with improved accuracy, the relationship is described in terms of the typical chromatic dispersion coefficients at 1460, 1550 and 1625 nm, and chromatic dispersion slope coefficient at 1550 nm. These values, together with link length, $L_{Link}$ , can be used to calculate the typical dispersion for use in optical link design. + +See [b-ITU-T G-Sup39] for additional information on system design and the statistics of chromatic dispersion. + +### I.3 Differential group delay + +The differential group delay (DGD) is the difference in arrival times of the two polarization modes at a particular wavelength and time. For a link with a specific PMD coefficient, the DGD of the link varies randomly with time and wavelength as a Maxwell distribution that contains a single parameter, which is the product of the PMD coefficient of the link and the square root of the link length. The system impairment due to PMD at a specific time and wavelength depends on the DGD at that time and wavelength. So, means of establishing useful limits on the DGD distribution as it relates to the optical fibre cable PMD coefficient distribution and its limits have been developed and are documented in [b-IEC/TR 61282-3]. The metrics of the limitations of the DGD distribution follow: + +NOTE – The determination of the contribution of components other than optical fibre cable is beyond the scope of this Recommendation, but is discussed in [b-IEC/TR 61282-3]. + +Reference link length, $L_{Ref}$ : A maximum link length to which the maximum DGD and probability will apply. For longer link lengths, multiply the maximum DGD by the square root of the ratio of actual length to the reference length. + +Typical maximum cable length, $L_{Cab}$ : The maxima are assured when the typical individual cables of the concatenation or the lengths of the cables that are measured in determining the PMD coefficient distribution are less than this value. + +Maximum DGD, $DGD_{max}$ : The DGD value that can be used when considering optical system design. + +Maximum probability, $P_F$ : The probability that an actual DGD value exceeds $DGD_{max}$ . + +### I.4 Non-linear coefficient + +The effect of chromatic dispersion is interactive with the non-linear coefficient, $n_2/A_{eff}$ , regarding system impairments induced by non-linear optical effects (see [b-ITU-T G.663] and [ITU-T G.650.2]). Typical values vary with the implementation. The test methods for non-linear coefficient remain under study. + +### I.5 Tables of common typical values + +The values in Tables I.1 and I.2 are representative of concatenated optical fibre links according to clauses I.1 and I.3, respectively. The implied fibre induced maximum DGD values in Table I.2 are intended for guidance in regard to the requirement for other optical elements that may be in the link. + +**Table I.1 – Representative value of concatenated optical fibre link** + +| Attribute | Wavelength region | Typical link value (Note) | +|------------------------------------------------------------------------------------------------------------------------|-------------------|---------------------------| +| Attenuation coefficient | 1460 nm-1530 nm | 0.35 dB/km | +| | 1530 nm-1565 nm | 0.275 dB/km | +| | 1565 nm-1625 nm | 0.35 dB/km | +| Typical dispersion coefficient | $D_{1460}$ | TBD | +| | $D_{1550}$ | TBD | +| | $D_{1625}$ | TBD | +| | $S_{1550}$ | TBD | +| NOTE – Typical link value corresponds to the link attenuation coefficient used in [b-ITU-T G.957] and [b-ITU-T G.691]. | | | + +**Table I.2 – Differential group delay** + +| Maximum PMD Q
(ps/√km) | Link length
(km) | Implied fibre induced
maximum DGD
(ps) | Channel bit rates | +|-----------------------------------------------------------------|---------------------|----------------------------------------------|-------------------| +| No specification | | | Up to 2.5 Gbit/s | +| 0.5 | 400 | 25.0 | 10 Gbit/s | +| | 40 | 19.0 (Note) | 10 Gbit/s | +| | 2 | 7.5 | 40 Gbit/s | +| 0.20 | 3000 | 19.0 | 10 Gbit/s | +| | 80 | 7.0 | 40 Gbit/s | +| 0.10 | > 4000 | 12.0 | 10 Gbit/s | +| | 400 | 5.0 | 40 Gbit/s | +| NOTE – This value applies also for 10 Gigabit Ethernet systems. | | | | + +NOTE – Cable section length is 10 km except for the 0.10 ps/√km/> 4000 km link, where if set to 25 km, the probability level is $6.5 \times 10^{-8}$ . + +### I.6 Chromatic dispersion coefficient limits + +The equations bounding the chromatic dispersion coefficient vs wavelength are based on a survey for the ITU-T G.656 fibres. There were nine products from seven vendors. Each provided average and standard deviation as a function of wavelength for wavelengths from 1460 nm to 1625 nm in 5 nm increments. For wavelength and vendor, the average plus and minus three standard deviation was calculated. Then the minimum and maximum across vendors was calculated. These results were fitted with a line spline using a breakpoint at 1550 nm to minimize the sum of absolute values of the difference while maintaining the principle of including all the data within the envelope. + +The result is shown in Figure I.1. The dashed lines are the limits from clause 7. The rest of the data represents the survey results. + +![Line graph showing Chromatic dispersion coefficient [ps/nm·km] vs Wavelength [nm] for various fiber types (Type 1 to Type 9) and their +/- 3 sigma limits. The graph includes a red dashed box representing prior ITU-T G.656 limits and upper/lower limit curves.](1d529a819ad929684331c55eed6673bb_img.jpg) + +The graph plots the chromatic dispersion coefficient in ps/nm·km on the y-axis (ranging from 0.0 to 16.0) against wavelength in nm on the x-axis (ranging from 1440 to 1640). A red dashed rectangle indicates the prior ITU-T G.656 (ver.1, 2004) limits, spanning from approximately 1460 nm to 1625 nm and 2.0 to 14.0 ps/nm·km. Above this rectangle, a dashed black line represents the upper limit curve, and below it, another dashed black line represents the lower limit curve. Multiple solid lines represent the dispersion characteristics for different fiber types, each with a -3 sigma and +3 sigma limit. The fiber types shown are Type 1, Type 2, Type 3, Type 4, Type 6, Type 7, and Type 9. Most fiber types show an increasing trend in dispersion coefficient with wavelength, starting from around 1460 nm. Type 9 fibers generally exhibit the highest dispersion coefficients, while Type 6 fibers show the lowest. + +Line graph showing Chromatic dispersion coefficient [ps/nm·km] vs Wavelength [nm] for various fiber types (Type 1 to Type 9) and their +/- 3 sigma limits. The graph includes a red dashed box representing prior ITU-T G.656 limits and upper/lower limit curves. + +Figure I.1 – Table 1 fibre dispersion + +## Bibliography + +- [b-ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable.* +- [b-ITU-T G.663] Recommendation ITU-T G.663 (2000), *Application related aspects of optical amplifier devices and subsystems.* +- [b-ITU-T G.691] Recommendation ITU-T G.691 (2006), *Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers.* +- [b-ITU-T G.692] Recommendation ITU-T G.692 (1998), *Optical interfaces for multichannel systems with optical amplifiers.* +- [b-ITU-T G.693] Recommendation ITU-T G.693 (2009), *Optical interfaces for intra-office systems.* +- [b-ITU-T G.694.2] Recommendation ITU-T G.694.2 (2003), *Spectral grids for WDM applications: CWDM wavelength grid.* +- [b-ITU-T G.695] Recommendation ITU-T G.695 (2009), *Optical interfaces for coarse wavelength division multiplexing applications.* +- [b-ITU-T G.696.1] Recommendation ITU-T G.696.1 (2005), *Longitudinally compatible intra-domain DWDM applications.* +- [b-ITU-T G.698.1] Recommendation ITU-T G.698.1 (2009), *Multichannel DWDM applications with single-channel optical interfaces.* +- [b-ITU-T G.957] Recommendation ITU-T G.957 (2006), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy.* +- [b-ITU-T G.959.1] Recommendation ITU-T G.959.1 (2009), *Optical transport network physical layer interfaces.* +- [b-ITU-T G-Sup39] ITU-T G-series Recommendations – Supplement 39 (2006), *Optical system design and engineering considerations.* +- [b-IEC 60794-2-11] IEC 60794-2-11 (2005), *Optical fibre cables – Part 2-11: Indoor cables – Detailed specification for simplex and duplex cables for use in premises cabling.* +- [b-IEC/TR 61282-3] IEC/TR 61282-3 (2006), *Fibre optic communication design guides – Part 3: Calculation of link polarization mode dispersion.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.666-201102-I_PDF-E/2834bdd6eb8540277e609decbb924003_img.jpg b/marked/G/T-REC-G.666-201102-I_PDF-E/2834bdd6eb8540277e609decbb924003_img.jpg new file mode 100644 index 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TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| General | G.600–G.609 | +| Symmetric cable pairs | G.610–G.619 | +| Land coaxial cable pairs | G.620–G.629 | +| Submarine cables | G.630–G.639 | +| Free space optical systems | G.640–G.649 | +| Optical fibre cables | G.650–G.659 | +| Characteristics of optical components and subsystems | G.660–G.679 | +| Characteristics of optical systems | G.680–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.666 + +## Characteristics of polarization mode dispersion compensators and of receivers that compensate for polarization mode dispersion + +## Summary + +Recommendation ITU-T G.666 contains parameters and definitions for devices providing polarization mode dispersion (PMD) compensation needed for transmission and detection of optical signals in a system exhibiting high levels of PMD which would otherwise cause unacceptable levels of system outage. Single and multichannel line PMD compensators are described, as well as single and multichannel PMD compensating receivers. Information on test configurations describing implementation examples of first order and second order PMD emulators and implementation options of PMD compensators can be found in informative appendices. + +This revised version adds an example implementation of a receiver-based single-channel optical polarization mode dispersion compensator (PMDC) to Appendix II. This new non-normative text is the only change relative to the 2008 version of this Recommendation. + +## History + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.666 | 2005-07-14 | 15 | +| 2.0 | ITU-T G.666 | 2008-03-29 | 15 | +| 3.0 | ITU-T G.666 | 2011-02-25 | 15 | + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2012 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|----------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Terms and definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 3 | +| 5 Reference configurations ..... | 4 | +| 5.1 Line PMDCs..... | 4 | +| 5.2 PMDC receivers ..... | 4 | +| 6 Parameters of PMDCs ..... | 5 | +| Appendix I – Measurements of parameters of PMDCs ..... | 9 | +| I.1 Measurement of parameters for PMDC receivers ..... | 9 | +| I.2 Measurement of parameters for line PMDCs..... | 11 | +| I.3 First order dynamic PMD emulator implementation..... | 11 | +| I.4 First and second order PMD emulator implementation ..... | 12 | +| Appendix II – Single-channel and multichannel PMDC receiver implementation ..... | 16 | +| II.1 Single-channel PMDC receiver implementation..... | 16 | +| II.2 Multichannel PMDC receiver implementation ..... | 17 | +| II.3 Optical single-channel PMDC implementation example..... | 17 | +| Bibliography..... | 19 | + + + +## Recommendation ITU-T G.666 + +# Characteristics of polarization mode dispersion compensators and of receivers that compensate for polarization mode dispersion + +# 1 Scope + +This Recommendation contains parameters and definitions for devices providing polarization mode dispersion (PMD) compensation needed for transmission and detection of optical signals in a system exhibiting high levels of PMD. The PMD compensating devices described include both single and multichannel applications. This Recommendation defines requirements and key parameters for first and higher order PMD compensators (PMDCs) and includes dynamic PMD characteristics. This Recommendation distinguishes line PMDCs from PMDC receivers which may comprise electrical as well as optical forms of PMD compensation. + +Measurement methods for PMD-related impairments can be found in [ITU-T G.650.2]. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.650.2] Recommendation ITU-T G.650.2 (2005), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable.* +- [ITU-T G.652] Recommendation ITU-T G.652 (2005), *Characteristics of a single-mode optical fibre and cable.* +- [ITU-T G.653] Recommendation ITU-T G.653 (2003), *Characteristics of a dispersion-shifted single-mode optical fibre and cable.* +- [ITU-T G.654] Recommendation ITU-T G.654 (2004), *Characteristics of a cut-off shifted single-mode optical fibre and cable.* +- [ITU-T G.655] Recommendation ITU-T G.655 (2003), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable.* +- [ITU-T G.656] Recommendation ITU-T G.656 (2004), *Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport.* +- [ITU-T G.661] Recommendation ITU-T G.661 (1998), *Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems.* +- [ITU-T G.662] Recommendation ITU-T G.662 (2005), *Generic characteristics of optical amplifier devices and subsystems.* +- [ITU-T G.665] Recommendation ITU-T G.665 (2005), *Generic characteristics of Raman amplifiers and Raman amplified subsystems.* +- [ITU-T G.671] Recommendation ITU-T G.671 (2005), *Transmission characteristics of optical components and subsystems.* +- [ITU-T G.694.1] Recommendation ITU-T G.694.1 (2002), *Spectral grids for WDM applications: DWDM frequency grid.* + +# 3 Terms and definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +**3.1.1 differential group delay (DGD)** [ITU-T G.650.2]: Symbol $\Delta\tau$ . + +**3.1.2 polarization dispersion vector (PDV)** [ITU-T G.650.2]: Symbol $\vec{\Omega}$ . + +NOTE – In a former version of this Recommendation, PDV was called "First order DGD vector". The renaming is due to an alignment of terms with respect to [ITU-T G.650.2]. + +**3.1.3 principal state of polarization vector** [ITU-T G.650.2]: Symbol $\vec{p}$ . + +**3.1.4 ripple** [ITU-T G.671]. + +**3.1.5 spectral excursion** [ITU-T G.698.1]. + +**3.1.6 Stokes vector** [ITU-T G.650.2]: Symbol $\vec{s}$ . + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 differential group delay (DGD) rate of change:** The DGD rate of change is defined as the absolute value of the derivative of the DGD with respect to time, i.e., $\left| \frac{\partial \Delta\tau}{\partial t} \right|$ , and is measured in ps/ms. + +**3.2.2 optical signal-to-noise ratio (OSNR) penalty due to DGD:** An optical signal that has been subject to a DGD requires a larger OSNR at the receiver to achieve $\text{BER} = 10^{-12}$ than an optical signal which has not been affected by DGD (i.e., $\Delta\tau = 0$ ), assuming the same receiver input power in both cases. This OSNR difference is called the OSNR penalty due to DGD. In this case, no second-order polarization mode dispersion (SOPMD) is considered. + +NOTE – For applications where FEC bytes are required to be transmitted, the BER of $10^{-12}$ is required to be met only after the error correction (if used) has been applied. The BER at the input of the FEC decoder for these cases can therefore be significantly higher than $10^{-12}$ . + +**3.2.3 polarization rotation speed (PRS):** The polarization rotation speed is the absolute value of the temporal change of the Stokes vector $\vec{s}$ , i.e., $\text{PRS} = \left| \frac{\partial \vec{s}}{\partial t} \right|$ , and is measured in rad/ms. + +**3.2.4 polarization mode dispersion compensator (PMDC) receiver sensitivity:** The value of the mean received power at point MPI-R needed to achieve the specified BER. This must be met across all states of input polarization with a worst-case transmitter, but does not have to be met with degradations of the optical path other than the PMD. + +**3.2.5 principal state of polarization (PSP) rate of change:** The PSP rate of change is defined as the derivative of the principal state of polarization vector $\vec{p}$ in Stokes space with respect to time, i.e., $\left| \frac{\partial \vec{p}}{\partial t} \right|$ , and is measured in rad/ms. + +**3.2.6 second-order PMD (SOPMD):** Second-order PMD is defined by $SOPMD = \bar{\Omega}_\omega = \Delta\tau_\omega \bar{p} + \Delta\tau \bar{p}_\omega$ . This is the derivative of the polarization dispersion vector (PDV) (first-order DGD vector) with respect to the optical frequency $\omega$ . The SOPMD consists of two terms, namely $\Delta\tau_\omega \bar{p}$ and $\Delta\tau \bar{p}_\omega$ . The first term, $\Delta\tau_\omega \bar{p}$ , represents the polarization-dependent chromatic dispersion term (PCD), while $\Delta\tau \bar{p}_\omega$ is the so-called depolarization term (DEPOL) which describes the PSP unit vector rotation with respect to frequency (at the centre frequency of the signal). The corresponding magnitudes of these quantities are given as follows: Magnitude of the SOPMD = $|\bar{\Omega}_\omega|$ , magnitude of the depolarization = $|\Delta\tau \bar{p}_\omega|$ , magnitude of the PCD = $|\Delta\tau_\omega|$ . + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-----------|-------------------------------------------------------------------| +| BER | Bit Error Ratio | +| DEMUX | Demultiplexer | +| DEPOL | Depolarization term | +| DGD | Differential Group Delay | +| DP | Degree of Polarization | +| LPMDC | Line Polarization Mode Dispersion Compensator | +| M-LPMDC | Multichannel Line Polarization Mode Dispersion Compensator | +| M-PMDC-Rx | Multichannel Polarization Mode Dispersion Compensating Receiver | +| MPI | Main Path Interface | +| MUX | Multiplexer | +| NRZ | Non-Return to Zero | +| OA | Optical Amplifier | +| O-E-O | Optical-Electrical-Optical (conversion) | +| OSNR | Optical Signal-to-Noise Ratio | +| PCD | Polarization-dependent Chromatic Dispersion | +| PDL | Polarization Dependent Loss | +| PDV | Polarization Dispersion Vector | +| PMD | Polarization Mode Dispersion | +| PMDC | Polarization Mode Dispersion Compensator | +| PMDC-Rx | Polarization Mode Dispersion Compensating Receiver | +| PRBS | Pseudo-Random Binary Sequence | +| PRS | Polarization Rotation Speed | +| PSP | Principal State of Polarization | +| RZ | Return to Zero | +| S-LPMDC | Single-Channel Line Polarization Mode Dispersion Compensator | +| S-PMDC-Rx | Single-Channel Polarization Mode Dispersion Compensating Receiver | +| SOP | State of Polarization | + +| | | +|-------|-------------------------------------------| +| SOPMD | Second-Order Polarization Mode Dispersion | +| Tx | Transmitter | +| WDM | Wavelength Division Multiplexing | + +# 5 Reference configurations + +PMDCs are intended to be used in optical transmission systems in order to reduce PMD-induced signal degradations. Therefore, characteristics of PMDCs must be considered, at least in part, in conjunction with a whole transmission system. + +A generic configuration of a transmission system with PMDC(s) is shown in Figure 5-1. It consists of a transmitter terminal, a receiver terminal and a transmission link in between with optional line PMDC(s). A single-channel system contains a single-channel transmitter and receiver terminal while a multichannel transmitter and receiver terminal is used in a multichannel system. The receiver terminal can also contain optional PMDC functionalities and is called a "PMDC receiver" in this case. In the following clauses, optical line PMDCs (LPMDCs) are distinguished from PMDC receivers. A black box approach is applied for the PMDCs and PMDC receivers. Monitoring and control (if present) is included in the black box. + +![Figure 5-1: Generic configuration of a transmission system with PMDCs. The diagram shows a 'Transmitter terminal' connected via an 'MPI-S' interface to a 'Transmission link with optional line PMDC(s)'. This link is connected via an 'MPI-R' interface to a 'Receiver terminal with optional PMDC(s)'. The diagram is labeled G.666_F5-1.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg) + +Figure 5-1: Generic configuration of a transmission system with PMDCs. The diagram shows a 'Transmitter terminal' connected via an 'MPI-S' interface to a 'Transmission link with optional line PMDC(s)'. This link is connected via an 'MPI-R' interface to a 'Receiver terminal with optional PMDC(s)'. The diagram is labeled G.666\_F5-1. + +Figure 5-1 – Generic configuration of a transmission system with PMDCs + +## 5.1 Line PMDCs + +Line PMDCs have an optical input and an optical output port and no O-E-O conversion is performed inside a line PMDC. A single-channel line PMDC (S-LPMDC) can handle a single-channel optical signal, while a multichannel line PMDC (M-LPMDC) is constructed for a multichannel optical signal. Both types are illustrated schematically in Figures 5-2 and 5-3, respectively. + +![Figure 5-2: Reference configuration of a single-channel line PMDC (S-LPMDC). The diagram shows an optical signal entering a box labeled 'S-LPMDC' from the left through an input port labeled R_S. The signal exits the box through an output port labeled S_S to the right. Optical connectors are shown at both the input and output. The diagram is labeled G.666_F5-2.](54fabc351eda5228d2fa28cd9ba07971_img.jpg) + +Figure 5-2: Reference configuration of a single-channel line PMDC (S-LPMDC). The diagram shows an optical signal entering a box labeled 'S-LPMDC' from the left through an input port labeled R\_S. The signal exits the box through an output port labeled S\_S to the right. Optical connectors are shown at both the input and output. The diagram is labeled G.666\_F5-2. + +Figure 5-2 – Reference configuration of a single-channel line PMDC (S-LPMDC) + +![Figure 5-3: Reference configuration of a multichannel line PMDC (M-LPMDC). The diagram shows an optical signal entering a box labeled 'M-LPMDC' from the left through an input port labeled R_M. The signal exits the box through an output port labeled S_M to the right. Optical connectors are shown at both the input and output. The diagram is labeled G.666_F5-3.](b0211cee4b20034939d883ac0d70f696_img.jpg) + +Figure 5-3: Reference configuration of a multichannel line PMDC (M-LPMDC). The diagram shows an optical signal entering a box labeled 'M-LPMDC' from the left through an input port labeled R\_M. The signal exits the box through an output port labeled S\_M to the right. Optical connectors are shown at both the input and output. The diagram is labeled G.666\_F5-3. + +Figure 5-3 – Reference configuration of a multichannel line PMDC (M-LPMDC) + +## 5.2 PMDC receivers + +In the case of PMDC receivers (PMDC-Rx), the PMDC functionality is embedded in the receiver terminal. There are a number of options regarding how to realize PMDC receivers. Single-channel PMDC receivers are distinguished from multichannel PMDC receivers. + +A schematic diagram of a single-channel PMDC receiver (S-PMDC-Rx) is shown in Figure 5-4. A single-channel optical signal enters the receiver terminal at the reference point MPI-R. There, the PMDC functionality is performed and the signal is then detected. Implementation details on single-channel PMDC receivers (e.g., optical vs electrical) can be found in Appendix II. + +![Figure 5-4: Reference configuration of a single-channel PMDC receiver. The diagram shows an optical signal entering a 'Single-channel PMDC receiver (S-PMDC-Rx)' at the reference point MPI-R. The signal is represented by a blue line with two circles at the input. The receiver is a grey box with a red border. The label 'G.666_F5-4' is in the bottom right corner.](5b4e774d63e0e0ed73801a9247755e5f_img.jpg) + +Figure 5-4: Reference configuration of a single-channel PMDC receiver. The diagram shows an optical signal entering a 'Single-channel PMDC receiver (S-PMDC-Rx)' at the reference point MPI-R. The signal is represented by a blue line with two circles at the input. The receiver is a grey box with a red border. The label 'G.666\_F5-4' is in the bottom right corner. + +**Figure 5-4 – Reference configuration of a single-channel PMDC receiver** + +A multichannel PMDC receiver is presented schematically in Figure 5-5. A multichannel optical signal enters the receiver terminal at the reference point MPI-R. There, it either passes a PMDC before entering a demultiplexer (DEMUX) and the receivers (Rx) for the individual optical channels, or it passes directly through the demultiplexer where all of the receivers are PMDC-Rx. Further implementation details can be found in clause II.2. + +![Figure 5-5: Reference configuration of a multichannel PMDC receiver (M-PMDC-Rx). The diagram shows an optical signal entering a 'Multichannel PMDC receiver' at the reference point MPI-R. Inside the receiver, the signal can pass through an 'Optional PMDC' (yellow box with a dashed green border) or directly to a 'DEMUX' (white box). The DEMUX outputs to multiple '(PMDC) Rx' (yellow boxes with red borders). The label 'M-PMDC-Rx' is at the bottom left of the receiver box. The label 'G.666_F5-5' is in the bottom right corner.](d26959f4514c26ca19c3d6f00da85956_img.jpg) + +Figure 5-5: Reference configuration of a multichannel PMDC receiver (M-PMDC-Rx). The diagram shows an optical signal entering a 'Multichannel PMDC receiver' at the reference point MPI-R. Inside the receiver, the signal can pass through an 'Optional PMDC' (yellow box with a dashed green border) or directly to a 'DEMUX' (white box). The DEMUX outputs to multiple '(PMDC) Rx' (yellow boxes with red borders). The label 'M-PMDC-Rx' is at the bottom left of the receiver box. The label 'G.666\_F5-5' is in the bottom right corner. + +**Figure 5-5 – Reference configuration of a multichannel PMDC receiver (M-PMDC-Rx)** + +# 6 Parameters of PMDCs + +In this clause, parameters for PMDCs are presented. Some parameters apply to all PMDC types and they are summarized in Table 6-1. In the following Tables 6-2 to 6-5, additional parameters can be found which apply to the individual PMDC types. + +**Table 6-1 – Common parameters which apply to all PMDC types** + +| Parameters | Reference point | Unit | Examples (for illustration of particular applications only) | +|--------------------------------------------|-------------------------------------------------------------------------|------|--------------------------------------------------------------------------------| +| Fibre type | | | | +| Line fibre type | MPI-S → R S or
MPI-S → R M or
MPI-S → MPI-R | – | ITU-T G.652.D,
ITU-T G.653,
ITU-T G.654,
ITU-T G.655,
ITU-T G.656. | +| Parameters related to optical power | | | | +| Minimum total input power | R S or R M or MPI-R | dBm | | +| Maximum total input power | R S or R M or MPI-R | dBm | | +| Maximum reflectance at the input port | R S or R M or MPI-R | dB | | + +**Table 6-1 – Common parameters which apply to all PMDC types** + +| Parameters | Reference point | Unit | Examples (for illustration of particular applications only) | +|--------------------------------------------------------------------------|---------------------------------------------------------------------------------------|-----------------|--------------------------------------------------------------------| +| Polarization dependent reflectance at the input port | $R_S$ or $R_M$ or MPI-R | dB | | +| Optical signal characteristics | | | | +| Minimum bit rate | $R_S$ or $R_M$ or MPI-R | Gbit/s | | +| Maximum bit rate | $R_S$ or $R_M$ or MPI-R | Gbit/s | | +| Modulation format (or "signal format") | $R_S$ or $R_M$ or MPI-R | – | "Any format", "only NRZ", "NRZ and RZ" | +| Polarization-independent parameters of the preceding optical path | | | | +| Minimum amount of accumulated chromatic dispersion | MPI-S $\rightarrow R_S$ or
MPI-S $\rightarrow R_M$ or
MPI-S $\rightarrow MPI-R$ | ps/nm | | +| Maximum amount of accumulated chromatic dispersion | MPI-S $\rightarrow R_S$ or
MPI-S $\rightarrow R_M$ or
MPI-S $\rightarrow MPI-R$ | ps/nm | | +| Polarization parameters at the input port | | | | +| Maximum average input DGD | $R_S$ or $R_M$ or MPI-R | ps | | +| Maximum instantaneous input DGD | $R_S$ or $R_M$ or MPI-R | ps | | +| Maximum polarization rotation speed | $R_S$ or $R_M$ or MPI-R | rad/ms | | +| Maximum DGD rate of change | $R_S$ or $R_M$ or MPI-R | ps/ms | | +| PSP rate of change | $R_S$ or $R_M$ or MPI-R | rad/ms | | +| Maximum magnitude of the PCD | $R_S$ or $R_M$ or MPI-R | ps 2 | | +| Maximum magnitude of the depolarization | $R_S$ or $R_M$ or MPI-R | ps 2 | | + +**Table 6-2 – Parameters which apply to a single-channel line PMDC (S-LPMDC)** + +| Parameters | Reference point | Unit | Examples (for illustration of particular applications only) | +|--------------------------------------------------|------------------------|-------------|--------------------------------------------------------------------| +| General single-channel optical parameters | | | | +| Nominal central optical frequency | $R_S$ | THz | | +| Maximum spectral excursion | $R_S$ | GHz | | +| Parameters related to optical power | | | | +| Minimum insertion loss (incl. optional OA unit) | $R_S \rightarrow S_S$ | dB | | +| Maximum insertion loss (incl. optional OA unit) | $R_S \rightarrow S_S$ | dB | | +| Maximum insertion loss deviation | $R_S \rightarrow S_S$ | dB | | +| Ripple | $R_S \rightarrow S_S$ | dB | | +| Noise figure (if an OA unit is used) | $R_S \rightarrow S_S$ | dB | | + +**Table 6-2 – Parameters which apply to a single-channel line PMDC (S-LPMDC)** + +| Parameters | Reference point | Unit | Examples (for illustration of particular applications only) | +|--------------------------------------------------------------------|-----------------------|-----------------|-------------------------------------------------------------| +| Polarization dependent loss (PDL) | $R_S \rightarrow S_S$ | dB | | +| Polarization parameters related to the output port (Note 1) | | | | +| Maximum average output DGD (Note 2) | $S_S$ | ps | | +| Maximum instantaneous output DGD (Note 2) | $S_S$ | ps | | +| Maximum magnitude of the SOPMD (Note 2) | $S_S$ | ps 2 | | + +NOTE 1 – In order to ensure transverse compatibility between line PMDCs and optical receivers, additional parameters may be required. +NOTE 2 – These parameters must be met for input PMD within the limits indicated in the "polarization parameters at the input port" section in Table 6-1. + +**Table 6-3 – Parameters which apply to a multichannel line PMDC (M-LPMDC)** + +| Parameters | Reference point | Unit | Examples (for illustration of particular applications only) | +|---------------------------------------------------------|-----------------------|------|-------------------------------------------------------------| +| General multichannel optical parameters | | | | +| Maximum number of channels | $R_M$ | – | | +| Nominal channel central frequencies | $R_M$ | THz | $191.9 + 0.2 m$ , $m = 0$ to $19$ | +| Channel spacing | $R_M$ | GHz | 200 | +| Maximum spectral excursion | $R_M$ | GHz | | +| Parameters related to optical power | | | | +| Minimum channel input power | $R_M$ | dBm | | +| Maximum channel input power | $R_M$ | dBm | | +| Minimum channel insertion loss (incl. optional OA unit) | $R_M \rightarrow S_M$ | dB | | +| Maximum channel insertion loss (incl. optional OA unit) | $R_M \rightarrow S_M$ | dB | | +| Maximum channel insertion loss deviation | $R_M \rightarrow S_M$ | dB | | +| Ripple | $R_M \rightarrow S_M$ | dB | | +| Noise figure (if an OA unit is used) | $R_M \rightarrow S_M$ | dB | | +| Polarization dependent loss (PDL) | $R_M \rightarrow S_M$ | dB | | + +**Table 6-3 – Parameters which apply to a multichannel line PMDC (M-LPMDC)** + +| Parameters | Reference point | Unit | Examples (for illustration of particular applications only) | +|--------------------------------------------------------------------------------------------|-----------------|-----------------|-------------------------------------------------------------| +| Polarization parameters applied to each channel related to the output port (Note 1) | | | | +| Maximum average output DGD (Note 2) | $S_M$ | ps | | +| Maximum instantaneous output DGD (Note 2) | $S_M$ | ps | | +| Maximum magnitude of SOPMD (Note 2) | $S_M$ | ps 2 | | + +NOTE 1 – In order to ensure transverse compatibility between line PMDCs and optical receivers, additional parameters may be required. +NOTE 2 – These parameters must be met for input PMD within the limits indicated in the "polarization parameters at the input port" section in Table 6-1. + +**Table 6-4 – Parameters which apply to a single-channel PMDC receiver (S-PMDC-Rx)** + +| Parameters | Unit | Examples (for illustration of particular applications only) | +|------------------------------------------------------|------|-------------------------------------------------------------| +| General single-channel optical parameters | | | +| Nominal central optical frequency | THz | | +| Maximum spectral excursion | GHz | | +| Single-channel transmission system parameters | | | +| Maximum OSNR penalty due to DGD | dB | | +| Minimum PMDC receiver sensitivity | dBm | | + +**Table 6-5 – Parameters which apply to a multichannel PMDC receiver (M-PMDC-Rx)** + +| Parameters | Unit | Examples (for illustration of particular applications only) | +|----------------------------------------------------------------------------|------|-------------------------------------------------------------| +| General multichannel optical parameters | | | +| Maximum number of channels | – | | +| Nominal channel central frequencies | THz | $191.9 + 0.2 m$ , $m = 0$ to $19$ | +| Channel spacing | GHz | 200 | +| Maximum spectral excursion | GHz | | +| Parameters related to optical power | | | +| Minimum channel input power | dBm | | +| Maximum channel input power | dBm | | +| Multichannel transmission system parameters applied to each channel | | | +| Maximum OSNR penalty due to DGD | dB | | +| Minimum PMDC receiver sensitivity | dBm | | + +# Appendix I + +## Measurements of parameters of PMDCs + +(This appendix does not form an integral part of this Recommendation.) + +This appendix covers approaches to the measurement of the parameters of PMDCs. A test configuration should contain a transmission link with PMD tuning capabilities (thus including the transmission fibre and a PMD emulator) followed by the PMDC and a test instrumentation to measure the PMDC characteristics. + +There are two different categories of PMDCs, namely PMDC receivers and line PMDCs. PMDC receivers include S-PMDC-Rxs and M-PMDC-Rxs. Line PMDCs include S-LPMDCs and M-LPMDCs. A generic approach to measurement of parameters for these PMDCs is shown below. + +### I.1 Measurement of parameters for PMDC receivers + +A generic test configuration for measuring parameters of PMDC receivers is shown in Figure I.1. For reasons of simplicity, single-channel transmitter and receiver terminals are assumed. The single-channel optical signal passes a transmission link which contains an adjustable PMD emulator and an optical noise source. Additional optical components (not shown here) are used to ensure constant optical input power at the reference point MPI-R in front of the PMDC receiver. + +![Figure I.1 – Generic configuration for measuring parameters of PMDC receivers](bffdddb47fced140f8d17fdc2a29f592_img.jpg) + +``` +graph LR + Tx[Tx terminal] -- MPI-S --- TL + subgraph TL [Transmission link including modification of the PMD characteristics] + PMDE[PMD emulator] -- " " --- ONS[Optical noise source] + end + TL -- MPI-R --- Rx[Rx terminal] + subgraph Rx + PMDCR[PMDC Receiver] + end +``` + +The diagram shows a signal path from a Tx terminal on the left to an Rx terminal on the right. The Tx terminal is connected to a large box labeled "Transmission link including modification of the PMD characteristics" at reference point MPI-S. Inside this box, the signal passes through a "PMD emulator" and then an "Optical noise source". The output of the transmission link box is at reference point MPI-R, which connects to the Rx terminal. The Rx terminal contains a "PMDC Receiver". The diagram is labeled G.666\_FI-1. + +Figure I.1 – Generic configuration for measuring parameters of PMDC receivers + +**Figure I.1 – Generic configuration for measuring parameters of PMDC receivers** + +In order to measure the OSNR penalty with respect to DGD, a first order PMD emulator is adjusted to DGD values in the DGD interval $0 \leq \Delta\tau \leq \Delta\tau_{\max}$ . Here, $\Delta\tau$ denotes the differential group delay (DGD), and $\Delta\tau_{\max}$ is the limit of the first order PMD that the receiver is required to tolerate. + +**NOTE** – Most commercially available PMD emulators require a fixed input polarization of $45^\circ$ with respect to their input PSP for optimum operation. Thus, the state of polarization at the input of the PMD emulator has to be controlled. Two approaches for this are: + +- 1) A fixed and stable $45^\circ$ state of polarization is ensured at the input of the PMD emulator. In this case, the distance between the Tx terminal and the PMD emulator is usually very short, thus avoiding unwanted polarization fluctuations due to a long length of fibre. +- 2) If a long fibre section between the Tx terminal and the input of the PMD emulator is unavoidable, then the state of polarization at the input of the PMD emulator is usually random. In order to cope with this problem, a polarization controller which continuously rotates the polarization is inserted in front of the PMD emulator. As a consequence, the influence of the random polarization is averaged. The rotation speed of this polarization controller has to be adapted carefully to the input requirements of the PMDC receiver. + +The BER is measured versus OSNR (while maintaining a constant optical input power $P_{in}$ at MPI-R). The BER curve at a value $\Delta\tau > 0$ may be shifted with respect to the BER curve at zero DGD (i.e., at $\Delta\tau = 0$ ). A schematic view of this behaviour is shown in Figure I.2. The PMD-induced penalty at BER = $10^{-12}$ between a polarization state with DGD $\Delta\tau > 0$ and the zero DGD state ( $\Delta\tau = 0$ ) is denoted as $\delta\tau$ . + +![Figure I.2: Schematic view of the BER versus OSNR for zero and non-zero DGD Δτ. The graph shows two curves: a blue curve for (Δτ = 0) and a red curve for (Δτ > 0). The y-axis is BER and the x-axis is OSNR. A horizontal dashed line at BER = 10^-12 intersects both curves. The horizontal distance between the intersection points is labeled δτ(Δτ). The text G.666(08)_FI-2 is at the bottom right.](b05fbb6a015ea153c1e25245772b1a1b_img.jpg) + +Figure I.2: Schematic view of the BER versus OSNR for zero and non-zero DGD Δτ. The graph shows two curves: a blue curve for (Δτ = 0) and a red curve for (Δτ > 0). The y-axis is BER and the x-axis is OSNR. A horizontal dashed line at BER = 10^-12 intersects both curves. The horizontal distance between the intersection points is labeled δτ(Δτ). The text G.666(08)\_FI-2 is at the bottom right. + +**Figure I.2 – Schematic view of the BER versus OSNR for zero and non-zero DGD $\Delta\tau$** + +The measurement set-up shown in Figure I.1 can also be used to measure the OSNR penalty with respect to both the DGD and SOPMD. In this case, a second order PMD emulator is used. This PMD emulator can be adjusted to any pair of values $(\Delta\tau, \Omega')$ in the DGD interval $0 \leq \Delta\tau \leq \Delta\tau_{max}$ and the SOPMD interval $0 \leq \Omega' \leq \Omega'_{max}$ . Here, $\Delta\tau$ denotes the differential group delay (DGD), $\Omega' = |\bar{\Omega}_{\omega}|$ denotes the amount of SOPMD, whereby $\bar{\Omega}_{\omega}$ is the derivative of the PDV (first order DGD vector) $\bar{\Omega}(\omega)$ with respect to $\omega$ , and $\Delta\tau_{max}$ and $\Omega'_{max}$ are the limits of the DGD and SOPMD that the receiver is required to tolerate. + +The same principle is applied as shown in Figure I.2. However, the BER curves are measured as a function of two PMD parameters, namely DGD and SOPMD. A schematic view of this behaviour is shown in Figure I.3. + +![Figure I.3: Schematic view of the BER versus OSNR for zero and non-zero DGD Δτ and SOPMD Ω'. The graph shows two curves: a blue curve for (Δτ = 0, Ω' = 0) and a red curve for (Δτ > 0, Ω' > 0). The y-axis is BER and the x-axis is OSNR. A horizontal dashed line at BER = 10^-12 intersects both curves. The horizontal distance between the intersection points is labeled δτ(Δτ, Ω'). The text G.666(08)_FI-3 is at the bottom right.](fc857414626a8d94d132e12d9afe52a4_img.jpg) + +Figure I.3: Schematic view of the BER versus OSNR for zero and non-zero DGD Δτ and SOPMD Ω'. The graph shows two curves: a blue curve for (Δτ = 0, Ω' = 0) and a red curve for (Δτ > 0, Ω' > 0). The y-axis is BER and the x-axis is OSNR. A horizontal dashed line at BER = 10^-12 intersects both curves. The horizontal distance between the intersection points is labeled δτ(Δτ, Ω'). The text G.666(08)\_FI-3 is at the bottom right. + +**Figure I.3 – Schematic view of the BER versus OSNR for zero and non-zero DGD $\Delta\tau$ and SOPMD $\Omega'$** + +The BER is measured versus OSNR (rather than versus optical input power) at the reference point MPI-R for the following reason: PMD usually becomes an issue for very high data rates (10 Gbit/s and above) and long optically transparent link lengths. In other words, PMD usually becomes an issue in multi-span transmission systems which (per definition) include optical amplifiers (OAs). OSNR is a fundamental limitation of such multi-span systems due to noise accumulation of the OAs. The minimum OSNR that the system can tolerate is given by the minimum OSNR in the absence of any PMD-induced distortions plus the additional penalty $\delta\tau$ ( $\Delta\tau$ , $\Omega'$ ) due to the impact of DGD and SOPMD. The additional penalty $\delta\tau$ ( $\Delta\tau$ , $\Omega'$ ) in dB is represented by the amount that the OSNR must be improved in the presence of PMD to maintain the required BER. + +### I.2 Measurement of parameters for line PMDCs + +A generic test configuration for measuring parameters of line PMDCs is shown in Figure I.4. + +![Figure I.4: Generic configuration for measuring parameters of line PMDCs. The diagram shows an optical test signal source connected to a transmission link at MPI-S. The transmission link includes a modification of PMD characteristics and a PMD emulator. The output of the transmission link is connected to a line PMDC at R_S or R_M. The output of the line PMDC is connected to optical test equipment at S_S or S_M. The diagram is labeled G.666_FI-4.](8307f6b04df072c9332f9987e034272c_img.jpg) + +Figure I.4: Generic configuration for measuring parameters of line PMDCs. The diagram shows an optical test signal source connected to a transmission link at MPI-S. The transmission link includes a modification of PMD characteristics and a PMD emulator. The output of the transmission link is connected to a line PMDC at R\_S or R\_M. The output of the line PMDC is connected to optical test equipment at S\_S or S\_M. The diagram is labeled G.666\_FI-4. + +**Figure I.4 – Generic configuration for measuring parameters of line PMDCs** + +In the case of line PMDCs, only optical parameters are measured at the input and the output port of the line PMDC. The BER is not measured. + +### I.3 First order dynamic PMD emulator implementation + +Figure I.5 shows one possible realization of a test set-up suitable for the evaluation of a PMDC receiver with respect to dynamic DGD tolerance. Higher order effects cannot be measured with this set-up. + +The basic approach is to provide a PMD emulator (consisting of two deterministic polarization controllers with a DGD element in between) with completely deterministic settings. The deterministic behaviour includes dynamic changes of the state of polarization (SOP) with a well-defined polarization rotation speed (PRS, measured in rad/ms). With random polarization scrambling, the maximum PRS can be selected, but it will only rarely be present. The same is true for the polarization at the input of the DGD element, which sets the signal distortion. With deterministic scrambling, it is possible to test the PMDC receiver under worst-case conditions and therefore to reduce measurement time and increase reproducibility of the results dramatically. + +![Figure I.5: Possible test set-up for characterizing the first order PMD tolerance of a PMDC receiver. The diagram shows a Tx terminal connected to a deterministic polarization controller (PC1) and an inline polarimeter. This is followed by a DGD element (tau). The signal then passes through another deterministic polarization controller (PC2) and an inline polarimeter. The output is connected to an Rx terminal at MPI-R. The Rx terminal is connected to a PMDC-receiver, which is connected to an error detector. An optical noise source is also connected to the Rx terminal. The diagram is labeled G.666(08)_FI-5.](29f586959675cafdf81cf934954908eb_img.jpg) + +Figure I.5: Possible test set-up for characterizing the first order PMD tolerance of a PMDC receiver. The diagram shows a Tx terminal connected to a deterministic polarization controller (PC1) and an inline polarimeter. This is followed by a DGD element (tau). The signal then passes through another deterministic polarization controller (PC2) and an inline polarimeter. The output is connected to an Rx terminal at MPI-R. The Rx terminal is connected to a PMDC-receiver, which is connected to an error detector. An optical noise source is also connected to the Rx terminal. The diagram is labeled G.666(08)\_FI-5. + +**Figure I.5 – Possible test set-up for characterizing the first order PMD tolerance of a PMDC receiver** + +In the case that the input polarization to the dynamic PMD emulator is stable over the measurement time (normal scenario), the inline polarimeters are only used during the calibration process of the PMD emulator. For applications where this is not the case, the inline polarimeter at PC1 can be used to detect changes of the input polarization and a correction via PC1 can be implemented. After calibration, the polarization controllers can be used to set the SOP, the PRS and the PSP rate of change in a deterministic way. The first polarization controller (PC1) is used to adjust the SOP at the input of the DGD element and therefore to set the PRS and worst-case polarization (i.e., continuously rotating the SOP such that the power splitting between the fast and slow axis of the DGD element changes continuously from 0 to 0.5 to 1 to 0.5, and so on). The second polarization controller (PC2) is used to rotate the PSP of the PMD emulator with a predefined PSP rate of change. This results in a relative change of the emulator PSP to the PSP of any DGD element which is possibly used inside the PMDC-receiver. A calibration procedure can be used to find the appropriate settings of PC2 corresponding to the desired values of the PSP rate of change. For testing the PMDC receiver, both PCs can be operated simultaneously. The PRS at MPI-R will be a result of the PRS induced by PC1 and the PSP rate of change induced by PC2. + +### I.4 First and second order PMD emulator implementation + +This clause shows an implementation example for the evaluation of a PMDC receiver with respect to static PMD tolerance for first order and second order PMD. Unlike the arrangement described in clause I.3, this implementation is not able to apply or track fast PMD changes. + +#### I.4.1 Measurement procedure + +The measurement set-up is shown in Figure I.6. Between the transmitter (Tx) and PMDC receiver are inserted a polarization scrambler, PMD emulator and chromatic dispersion emulator. This enables a known magnitude of first and second order PMD to be applied together with a known amount of chromatic dispersion. An optical noise source is also included to provide noise loading at the input of the PMDC receiver. + +![Figure I.6: Measurement set-up for determination of first and second order PMD tolerance. The diagram shows a Tx (Transmitter) connected to an MPI-S (Main Interface-S), which is connected to a Polarization scrambler. The Polarization scrambler is connected to a PMD emulator (1st + 2nd order), which is connected to a Chromatic dispersion emulator. The output of the Chromatic dispersion emulator is split into three paths: one path goes to an MPI-R (Main Interface-R), which is connected to a PMDC-receiver; the other two paths go to an Optical noise source and an Optical spectrum analyser. The PMDC-receiver is connected to an Error detector. A Pattern generator is connected to the Tx via a PRBS (Pseudo Random Bit Sequence) input. The diagram is labeled G.666(08)_FI-6.](9cd90f495b95ad2116ff780248c26d95_img.jpg) + +``` + +graph LR + Tx[Tx] -- MPI-S --> PS[Polarization scrambler] + PS --> PMD[PMD emulator 1st + 2nd order] + PMD --> CDE[Chromatic dispersion emulator] + CDE --> Split(( )) + Split --> MPI-R[MPI-R] + Split --> ONS[Optical noise source] + Split --> OSA[Optical spectrum analyser] + MPI-R --> PMDC[PMDC-receiver] + PMDC --> ED[Error detector] + PG[Pattern generator] -- PRBS --> Tx + +``` + +Figure I.6: Measurement set-up for determination of first and second order PMD tolerance. The diagram shows a Tx (Transmitter) connected to an MPI-S (Main Interface-S), which is connected to a Polarization scrambler. The Polarization scrambler is connected to a PMD emulator (1st + 2nd order), which is connected to a Chromatic dispersion emulator. The output of the Chromatic dispersion emulator is split into three paths: one path goes to an MPI-R (Main Interface-R), which is connected to a PMDC-receiver; the other two paths go to an Optical noise source and an Optical spectrum analyser. The PMDC-receiver is connected to an Error detector. A Pattern generator is connected to the Tx via a PRBS (Pseudo Random Bit Sequence) input. The diagram is labeled G.666(08)\_FI-6. + +**Figure I.6 – Measurement set-up for determination of first and second order PMD tolerance** + +The PMD emulator is set to different combinations of first and second order PMD and the BER and OSNR values are measured with an optical spectrum analyser (OSA) and bit error ratio tester (BERT), respectively. As a result, a certain OSNR penalty with respect to the undistorted case is measured as illustrated in Figure I.7. In this figure, the X and Y axes are the magnitude of the first order (DGD) and second order PMD (SOPMD) respectively, and the lines are contours of constant OSNR penalty (in dB). This plot is also called a two-dimensional distortion plane. + +During the measurement process, all points in this plane need to be measured or, more practically, obtained by interpolation from measurements in the neighbourhood. For the example shown in Figure I.7, the allowable OSNR penalty is set at 2.0 dB maximum and the region where this penalty is exceeded is shown shaded. + +![Figure I.7: A plot showing constant OSNR penalty contours for first and second order PMD. The x-axis is DGD (ps) and the y-axis is SOPMD (ps²). Contours are labeled 0.5, 1.0, 1.5, and 2.0. A shaded region at the top right indicates OSNR penalty > 2.0 dB. The plot is labeled G.666(08)_FI-7.](b2d16e07bfa79d67a8adabf7e26c7764_img.jpg) + +Figure I.7: A plot showing constant OSNR penalty contours for first and second order PMD. The x-axis is DGD (ps) and the y-axis is SOPMD (ps²). Contours are labeled 0.5, 1.0, 1.5, and 2.0. A shaded region at the top right indicates OSNR penalty > 2.0 dB. The plot is labeled G.666(08)\_FI-7. + +**Figure I.7 – Example lines of constant OSNR penalty for first and second order PMD (DGD and SOPMD)** + +The shape of this two-dimensional distortion plane, however, also depends on the value of the chromatic dispersion present in the link, so this whole measurement procedure must be repeated for various levels of chromatic dispersion, including the limiting residual dispersion values of the target application. + +Measurement examples of this two-dimensional distortion plane have been published [b-Klekamp] for 43 Gbit/s NRZ and RZ formats without additional chromatic dispersion emulation. + +Figure I.8 shows the joint probability density function for first and second order PMD. The axes are the same as for Figure I.7, but the lines are now drawn through points of equal probability of occurrence. This is the joint probability density function (pdf $p_j$ ) for a particular value of mean DGD. + +![Figure I.8: A plot showing the joint probability density function for first and second order PMD. The x-axis is DGD (ps) and the y-axis is SOPMD (ps²). Contours represent constant probability levels, labeled from 10⁻² to 10⁻⁹. The plot is labeled G.666(08)_FI-8.](93587f920736a2fdcefeba94b29f302a_img.jpg) + +Figure I.8: A plot showing the joint probability density function for first and second order PMD. The x-axis is DGD (ps) and the y-axis is SOPMD (ps²). Contours represent constant probability levels, labeled from 10⁻² to 10⁻⁹. The plot is labeled G.666(08)\_FI-8. + +**Figure I.8 – Joint probability density function for first and second order PMD (DGD and SOPMD)** + +#### I.4.2 PMD vector in Stokes space + +Generally, PMD can be described by a Taylor series according to: + +$$\vec{\Omega}(\omega_0 + \Delta\omega) = \vec{\Omega}(\omega_0) + \vec{\Omega}' \cdot \Delta\omega + \dots \quad (I-1)$$ + +Focusing on the first and second order contribution, the PMD is determined by the PDV (first order DGD vector) $\vec{\Omega}(\omega_0)$ with $\omega_0$ as the signal centre frequency and the second order PMD vector: + +$$\text{SOPMD} = \vec{\Omega}' = \vec{\Omega}_{\omega_0} = \Delta\tau_{\omega_0} \vec{p} + \Delta\tau \vec{p}_{\omega_0} \quad (\text{I-2})$$ + +Figure I.9 depicts possible orientations of different PMD contributions in Stokes space together with the signal state of polarization $\vec{s}$ . + +![Figure I.9: PMD vectors in Stokes space. The diagram shows a 3D coordinate system with a vertical axis. A vector labeled \vec{\Omega} = \Delta\tau \vec{p} points along the vertical axis. A vector labeled \vec{\Omega}' = \vec{\Omega}_{\omega_0} = \Delta\tau_{\omega_0} \vec{p} + \Delta\tau \vec{p}_{\omega_0} points at an angle \xi from the vertical axis. A vector labeled \Delta\tau_{\omega_0} \vec{p} = PCD points at an angle \theta from the vertical axis. A vector labeled \Delta\tau \vec{p}_{\omega_0} = DEPOL points at an angle \phi from the vertical axis. A vector labeled \vec{s} points at an angle \theta from the vertical axis. The diagram is labeled G.666(08)_FI-9.](63c666b05041841b01fdef9fa4153ff7_img.jpg) + +Figure I.9: PMD vectors in Stokes space. The diagram shows a 3D coordinate system with a vertical axis. A vector labeled \vec{\Omega} = \Delta\tau \vec{p} points along the vertical axis. A vector labeled \vec{\Omega}' = \vec{\Omega}\_{\omega\_0} = \Delta\tau\_{\omega\_0} \vec{p} + \Delta\tau \vec{p}\_{\omega\_0} points at an angle \xi from the vertical axis. A vector labeled \Delta\tau\_{\omega\_0} \vec{p} = PCD points at an angle \theta from the vertical axis. A vector labeled \Delta\tau \vec{p}\_{\omega\_0} = DEPOL points at an angle \phi from the vertical axis. A vector labeled \vec{s} points at an angle \theta from the vertical axis. The diagram is labeled G.666(08)\_FI-9. + +**Figure I.9 – PMD vectors $\Omega$ (first order) and $\Omega'$ (second order), including PCD, DEPOL and signal state of polarization (SOP) $\vec{s}$** + +#### I.4.3 Calculation of outage probability (OP) versus first and second order PMD + +Generally, the distortion of a signal degraded by first and second order PMD and the corresponding outage probability can be quantified by numerical integration over a set of five parameters as reported in [b-Bülow] and [b-Foschini]: + +$$OP = \iiint \iiint_{OSNR\ penalty > limit} p_j^* d|\vec{\Omega}| d|\vec{\Omega}'| d\theta d\phi d\xi \quad (\text{I-3})$$ + +The measurement and calculation of the OP can be accelerated by a reduction of the PMD emulation to only two parameters, by: + +- Scrambling the state of polarization (SOP) of the signal during BER acquisition to eliminate the need to set the two angles $\theta$ and $\phi$ describing the orientation relative to the PSP vector $\vec{p}$ . +- Setting the mutual orientation ( $\xi$ ) between the first and second order PMD vectors $\Omega$ and $\Omega_{\omega_0}$ to 90 degrees in the PMD emulator. This corresponds to a worst-case distortion of the second order PMD (maximum depolarization and no PMD-induced chromatic dispersion). + +The reduction by three distortion parameters leads to the two dimensional pdf $p_j$ by the integration of $p_j^*$ over the angles $\theta$ , $\phi$ and $\xi$ . Thus, the outage probability formula (Equation I-3) can be simplified and expressed by: + +$$OP = \iint_{OSNR\ penalty > limit} p_j d|\vec{\Omega}| d|\vec{\Omega}'| \equiv \iint_{OSNR\ penalty > limit} p_j dDGD dSOPMD \quad (\text{I-4})$$ + +Finally, the outage probability is the numerical integration of the pdf $p_j$ over the area with the OSNR penalty exceeding the limit (shaded area in Figure I.7). The two integration parameters are the DGD in ps (magnitude of the first order PMD vector $\Omega$ ) and SOPMD, the second order PMD in ps/GHz or ps2 (magnitude of the second order PMD vector $\Omega'$ ), respectively. + +Figure I.10 shows an example of the calculated OP versus PMD derived from measurement of the two dimensional distortion plane using a 43 Gbit/s NRZ transmitter and receiver, with and without a receiver based PMDC. The X axis of Figure I.10 (labelled PMD) is equal to the mean DGD value which indicates the level of both first and second order PMD. An OSNR penalty of 2 dB has been applied as the OSNR penalty limit. If the outage probability that is considered acceptable is $10^{-5}$ , then the maximum input PMD of the receiver (PMD tolerance) at 2 dB of OSNR penalty are 2.7 ps and 4.5 ps for the cases without and with PMDC, respectively. + +![Figure I.10: Outage probability versus PMD at 43 Gbit/s NRZ, with and without PMDC. The graph shows two curves: 'Without PMDC' (blue squares) and 'With PMDC' (magenta circles). The Y-axis is Outage probability (log scale from 1.E+00 to 1.E-08) and the X-axis is PMD (ps) (linear scale from 0 to 10). The 'Without PMDC' curve drops sharply, reaching 1.E-05 at approximately 2.7 ps. The 'With PMDC' curve drops more gradually, reaching 1.E-05 at approximately 4.5 ps.](f8630b0582d6e5b1d81f877880ef0dda_img.jpg) + +| PMD (ps) | Outage probability (Without PMDC) | Outage probability (With PMDC) | +|----------|-----------------------------------|--------------------------------| +| 2.5 | 1.E-08 | - | +| 3.0 | 1.E-05 | - | +| 3.5 | 1.E-06 | - | +| 4.0 | 1.E-07 | - | +| 4.5 | - | 1.E-05 | +| 5.0 | - | 1.E-06 | +| 6.0 | - | 1.E-07 | +| 8.0 | - | 1.E-08 | + +Figure I.10: Outage probability versus PMD at 43 Gbit/s NRZ, with and without PMDC. The graph shows two curves: 'Without PMDC' (blue squares) and 'With PMDC' (magenta circles). The Y-axis is Outage probability (log scale from 1.E+00 to 1.E-08) and the X-axis is PMD (ps) (linear scale from 0 to 10). The 'Without PMDC' curve drops sharply, reaching 1.E-05 at approximately 2.7 ps. The 'With PMDC' curve drops more gradually, reaching 1.E-05 at approximately 4.5 ps. + +**Figure I.10 – Outage probability versus PMD at 43 Gbit/s NRZ, with and without PMDC** + +## Appendix II + +## Single-channel and multichannel PMDC receiver implementation + +(This appendix does not form an integral part of this Recommendation.) + +### II.1 Single-channel PMDC receiver implementation + +Single-channel PMDC receivers (as shown generically in Figure 5-4) can be realized by different implementation schemes. One option is a single-channel line PMDC (S-LPMDC) as presented in Figure II.1, together with a conventional receiver. The optical signal behind the reference point MPI-R passes through an optical PMDC before entering the receiver. The optional feedback loop shown with a dashed line in Figure II.1 allows the PMDC to operate in an optimized regime. + +![Figure II.1: Implementation option A of a single-channel PMDC receiver (S-PMDC-Rx).](7d3d5fb5d09c0cd35a9d637be241651e_img.jpg) + +The diagram shows an optical signal entering from the left at a reference point labeled MPI-R. The signal then enters a yellow rectangular block labeled 'PMDC'. This block is part of a larger system labeled 'S-PMDC-Rx'. To the right of the PMDC block is a red rectangular block labeled 'Rx'. A dashed line with arrows at both ends connects the top of the PMDC block to the top of the Rx block, representing an optional feedback loop. Above the PMDC and Rx blocks, the text 'Single-channel PMDC receiver' is present. The diagram is labeled 'G.666\_FII-1' in the bottom right corner. + +Figure II.1: Implementation option A of a single-channel PMDC receiver (S-PMDC-Rx). + +**Figure II.1 – Implementation option A of a single-channel PMDC receiver (S-PMDC-Rx)** + +An alternative implementation is the use of a receiver including electrical PMDC, as indicated in Figure II.2. No additional optical device is used for the purpose of PMD compensation. Instead, the PMDC function is achieved inside the receiver by electrical means. For example, in a coherent receiver, the PMD can be compensated by electronic processing in the receiver. + +![Figure II.2: Implementation option B of a single-channel PMDC receiver (S-PMDC-Rx).](b2ea162a0f53d5e0504b7d28346e0754_img.jpg) + +The diagram shows an optical signal entering from the left at a reference point labeled MPI-R. The signal then enters a red rectangular block labeled 'Rx including electrical PMDC'. The diagram is labeled 'G.666\_FII-2' in the bottom right corner. + +Figure II.2: Implementation option B of a single-channel PMDC receiver (S-PMDC-Rx). + +**Figure II.2 – Implementation option B of a single-channel PMDC receiver (S-PMDC-Rx)** + +A combination of the two above implementations is also possible, as shown in Figure II.3. + +![Figure II.3: Implementation option C of a single-channel PMDC receiver (S-PMDC-Rx).](2834bdd6eb8540277e609decbb924003_img.jpg) + +The diagram shows an optical signal entering from the left at a reference point labeled MPI-R. The signal then enters a yellow rectangular block labeled 'PMDC'. This block is part of a larger system labeled 'S-PMDC-Rx'. To the right of the PMDC block is a red rectangular block labeled 'PMDC-Rx'. A dashed line with arrows at both ends connects the top of the PMDC block to the top of the PMDC-Rx block, representing an optional feedback loop. Above the PMDC and PMDC-Rx blocks, the text 'Single-channel PMDC receiver' is present. The diagram is labeled 'G.666\_FII-3' in the bottom right corner. + +Figure II.3: Implementation option C of a single-channel PMDC receiver (S-PMDC-Rx). + +**Figure II.3 – Implementation option C of a single-channel PMDC receiver (S-PMDC-Rx)** + +### II.2 Multichannel PMDC receiver implementation + +Similarly to clause II.1, there are three implementation options for multichannel PMDC receivers. These are illustrated in Figures II.4 to II.6. Option A includes an optical PMDC in front of the demultiplexer with conventional receivers. Option B uses only PMDC receivers. Option C uses a combination of both an optical PMDC in front of the demultiplexer and PMDC receivers. + +![Figure II.4: Implementation option A of a multichannel PMDC receiver (M-PMDC-Rx).](d734a6ea1b381280f043fcf70391b6db_img.jpg) + +Diagram of Implementation option A. An optical fiber input labeled 'MPI-R' enters a 'Multichannel PMDC receiver' box. Inside, the signal passes through a 'PMDC' block (highlighted with a dashed green border). The output goes to a 'DEMUX' block. The DEMUX has multiple outputs; two are shown connected to yellow 'Rx' blocks, with three dots between them indicating multiple channels. The entire internal assembly is labeled 'M-PMDC-Rx'. Reference label 'G.666\_FII-4' is at the bottom right. + +Figure II.4: Implementation option A of a multichannel PMDC receiver (M-PMDC-Rx). + +**Figure II.4 – Implementation option A of a multichannel PMDC receiver (M-PMDC-Rx)** + +![Figure II.5: Implementation option B of a multichannel PMDC receiver (M-PMDC-Rx).](844077b3034f0030b404207db0ad76b4_img.jpg) + +Diagram of Implementation option B. An optical fiber input labeled 'MPI-R' enters a 'Multichannel PMDC receiver' box and goes directly to a 'DEMUX' block. The DEMUX outputs are connected to yellow 'PMDC Rx' blocks. Three dots indicate multiple channels. The assembly is labeled 'M-PMDC-Rx'. Reference label 'G.666\_FII-5' is at the bottom right. + +Figure II.5: Implementation option B of a multichannel PMDC receiver (M-PMDC-Rx). + +**Figure II.5 – Implementation option B of a multichannel PMDC receiver (M-PMDC-Rx)** + +![Figure II.6: Implementation option C of a multichannel PMDC receiver (M-PMDC-Rx).](ab846b81e78dbc8da2a6f9511e2f248a_img.jpg) + +Diagram of Implementation option C. An optical fiber input labeled 'MPI-R' enters a 'Multichannel PMDC receiver' box, passes through a 'PMDC' block (dashed green border), and then enters a 'DEMUX' block. The DEMUX outputs are connected to yellow 'PMDC Rx' blocks. Three dots indicate multiple channels. The assembly is labeled 'M-PMDC-Rx'. Reference label 'G.666\_FII-6' is at the bottom right. + +Figure II.6: Implementation option C of a multichannel PMDC receiver (M-PMDC-Rx). + +**Figure II.6 – Implementation option C of a multichannel PMDC receiver (M-PMDC-Rx)** + +### II.3 Optical single-channel PMDC implementation example + +A single-channel optical PMDC implementation example consists of two fast electro-optic polarization controllers, denoted as PC1 and PC2 and two pieces of polarization maintaining fibres with constant DGD elements of $\Delta\tau_1$ and $\Delta\tau_2$ , a fast optical polarimeter to provide a feedback signal that is indicating the deviation of the PMDC settings from optimal, and a control algorithm running on a fast controller, as shown in Figure II.7. The compensated degree of polarization (DOP) provides a reliable error signal, as directly related to the impairments coming from PMD. The + +optimization with respect to the applied modulation format, the tolerable receiver sensitivity penalty, the compensation limit, etc., depends on the choice of the two incorporated DGD elements $\Delta\tau_1$ and $\Delta\tau_2$ . + +![Block diagram of a two-stage optical PMDC implementation example. The diagram shows a sequence of blocks: PC1, Δτ1, PC2, Δτ2, and Polarimeter. A Controller block is connected to the output of the Polarimeter and has feedback lines to the PC1 and PC2 blocks.](73b5cce955ba9415a98791db7b0080ad_img.jpg) + +``` + +graph LR + In(( )) --> PC1[PC1] + PC1 --> DT1[Δτ1] + DT1 --> PC2[PC2] + PC2 --> DT2[Δτ2] + DT2 --> Polarimeter[Polarimeter] + Polarimeter --> Out(( )) + Polarimeter --> Controller[Controller] + Controller --> PC1 + Controller --> PC2 + +``` + +Block diagram of a two-stage optical PMDC implementation example. The diagram shows a sequence of blocks: PC1, Δτ1, PC2, Δτ2, and Polarimeter. A Controller block is connected to the output of the Polarimeter and has feedback lines to the PC1 and PC2 blocks. + +**Figure II.7 – Block diagram of a two-stage optical PMDC implementation example** + +The principle of the PMDC is shown in vector form in Figure II.8, where $\vec{\Omega}$ and $\vec{\Omega}_\omega$ are the first order and second order PMD vectors of the transmission link, respectively. Vectors $\vec{A}$ and $\vec{B}$ are the vectors of the first and second compensation sections of the PMDC. All the vectors are referenced to the input of the PMDC. The polarization controller PC2 controls the angle between $\vec{A}$ and $\vec{B}$ . The polarization controller PC1 will be adjusted to align $\vec{A} + \vec{B}$ versus $\vec{\Omega}$ , allowing for the compensation of the first-order PMD vector $\vec{\Omega}$ , as depicted in Figure II.8. Furthermore, PC1 may also control the rotation of $\vec{A}$ and $\vec{B}$ versus $\vec{\Omega}$ to align with $\vec{A} \times \vec{B}$ to become "anti-parallel" to the component of $(\vec{\Omega}_\omega \perp \vec{\Omega})$ , allowing for a partial compensation of the SOPMD vector $\vec{\Omega}_\omega$ . + +![Vector diagram in Stokes space showing PMD vectors. It depicts a vector addition where vector A (labeled Δτ₁ a) and vector B (labeled Δτ₂ b) sum to a vector that aligns with Ω (labeled Δτ p). A vertical vector Ω_ω is shown, with a horizontal component labeled (Ω_ω ⊥ Ω). A vector A × B is shown pointing away from the junction of A and B.](4b87467ad9642943235f48f7d4b59449_img.jpg) + +Vector diagram in Stokes space showing PMD vectors. It depicts a vector addition where vector A (labeled Δτ₁ a) and vector B (labeled Δτ₂ b) sum to a vector that aligns with Ω (labeled Δτ p). A vertical vector Ω\_ω is shown, with a horizontal component labeled (Ω\_ω ⊥ Ω). A vector A × B is shown pointing away from the junction of A and B. + +**Figure II.8 – PMD vectors in Stokes space** + +# Bibliography + +- [b-ITU-T G-Sup.39] ITU-T G-series Recommendations – Supplement 39 (2003), *Optical system design and engineering considerations*. +- [b-IEC/TR 61282-9] IEC/TR 61282-9 (2006), *Fibre optic communication system design guides – Part 9: Guidance on polarization mode dispersion measurements and theory*. +<> +- [b-Bülow] Bülow, H. (1998), *System Outage Probability Due to First- and Second-Order PMD*, IEEE Photonics Technology Letters, Vol. 10, No. 5, May, pp. 696-698. +- [b-Foschini] Foschini, J., Poole, C.D. (1991), *Statistical Theory of Polarization Dispersion in Single Mode Fibres*, Journal of Lightwave Technology, Vol. 9, No.11, pp. 1439-1456. +- [b-Klekamp] Klekamp, A., and Bülow, H. (2006), *Experimental Comparison of PMD Tolerances of Binary 43Gb/s Modulation Formats without and with PMD Compensation*, Technical Digest of ECOC 2006, paper Tu4.2.4. +- [b-Lanne] S. Lanne, *et al.* (2001), *Demonstration of adaptive PMD compensation at 40 Gb/s*, Proceedings OFC 2001, paper TuP3. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.697-201611-I_PDF-E/raw.md b/marked/G/T-REC-G.697-201611-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..357c9fed51c7b0c55bd2eb2e49dd06003cbacf43 --- /dev/null +++ b/marked/G/T-REC-G.697-201611-I_PDF-E/raw.md @@ -0,0 +1,996 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.697** + +(11/2016) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Transmission media and optical systems characteristics – +Characteristics of optical systems + +# --- **Optical monitoring for dense wavelength division multiplexing systems** + +Recommendation ITU-T G.697 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| General | G.600–G.609 | +| Symmetric cable pairs | G.610–G.619 | +| Land coaxial cable pairs | G.620–G.629 | +| Submarine cables | G.630–G.639 | +| Free space optical systems | G.640–G.649 | +| Optical fibre cables | G.650–G.659 | +| Characteristics of optical components and subsystems | G.660–G.679 | +| Characteristics of optical systems | G.680–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.697 + +# Optical monitoring for dense wavelength division multiplexing systems + +## Summary + +Recommendation ITU-T G.697 defines optical monitoring (OM) that can help in dense wavelength division multiplexing (DWDM) systems to perform the following activities: + +- configuration management for system and channel activation, addition of new channels, etc.; +- fault management to detect and to isolate faults; +- degradation management in order to keep the system running and to detect degradations before a fault occurs. + +DWDM technology is improving at a rapid pace, continuously stretching the channel count, channel speeds and reach limits. Long-haul multi-span DWDM systems are capable of taking optical signals thousands of kilometres without electrical terminations or regeneration. + +This continuing trend is driving the increasing importance of OM, which is the subject of this Recommendation. + +This edition of this Recommendation provides additional information on OM for 40 Gbit/s and 100 Gbit/s signals, adds beat noise method to the clause for optical signal-to-noise ratio (OSNR) measurements, and introduces a new clause on security considerations. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|---------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.697 | 2004-06-13 | 15 | 11.1002/1000/7322 | +| 2.0 | ITU-T G.697 | 2009-11-13 | 15 | 11.1002/1000/10394 | +| 2.1 | ITU-T G.697 (2009) Cor. 1 | 2011-02-25 | 15 | 11.1002/1000/11327 | +| 3.0 | ITU-T G.697 | 2012-02-13 | 15 | 11.1002/1000/11483 | +| 4.0 | ITU-T G.697 | 2016-11-13 | 15 | 11.1002/1000/13079 | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2017 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +| | | Page | +|-------|----------------------------------------------------------------------------------------------------------------------------------------------|------| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 2.1 | Normative references..... | 1 | +| 3 | Terms and definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation ..... | 2 | +| 4 | Abbreviations and acronyms ..... | 3 | +| 5 | Optical monitoring overview ..... | 4 | +| 6 | Classification of monitoring methods..... | 5 | +| 6.1 | Signal monitoring ..... | 5 | +| 6.2 | Equipment monitoring (indirect methods) ..... | 6 | +| 6.3 | Fibre link monitoring..... | 6 | +| 6.4 | Monitoring based on received signals ..... | 6 | +| 6.5 | Embedded monitoring equipment ..... | 6 | +| 6.6 | External monitoring equipment..... | 7 | +| 7 | Optical impairments..... | 7 | +| 8 | Optical monitoring parameters ..... | 9 | +| 9 | Correlation between impairment effects and optical monitoring parameters
degradation ..... | 10 | +| 9.1 | Variation of attenuation ..... | 10 | +| 9.2 | Frequency (or wavelength) deviation from nominal ..... | 10 | +| 9.3 | Optical channel power changes due to gain variations ..... | 10 | +| 10 | Applications..... | 11 | +| 11 | Optical safety considerations..... | 11 | +| 12 | Security considerations..... | 11 | +| | Appendix I – Severity of optical impairments ..... | 12 | +| | Appendix II – Penalty severity value X ..... | 14 | +| | Appendix III – Optical monitoring performance ..... | 15 | +| III.1 | Optical signal-to-noise ratio measurement ..... | 17 | +| III.2 | Q -factor measurement (for up to approximately 10 Gbit/s signals)..... | 21 | +| | Appendix IV – Possible positions for suitable monitoring equipment and their relative
functions in several optical network elements ..... | 25 | +| IV.1 | Introduction ..... | 25 | +| IV.2 | Embedded monitoring points ..... | 26 | +| IV.3 | External monitoring points ..... | 28 | + +| | Page | +|--------------------------------------------|-------------| +| Appendix V – Parameter encoding ..... | 30 | +| V.1    Wavelength ID (32 bits) ..... | 30 | +| V.2    Parameter ID source (8 bits)..... | 31 | +| V.3    Parameter ID (8 bits) ..... | 31 | +| V.4    Value of parameters (32 bits) ..... | 31 | +| Bibliography..... | 32 | + +## Recommendation ITU-T G.697 + +# Optical monitoring for dense wavelength division multiplexing systems + +# 1 Scope + +The purpose of this Recommendation is to indicate a minimum, but not exhaustive, set of optical parameters that can be used to perform optical monitoring (OM) functions in dense wavelength division multiplexing (DWDM) systems and optical network elements [ONEs, e.g., reconfigurable optical add-drop multiplexers (ROADMs)], particularly relevant to those network elements without optical-electrical-optical conversions. In order to achieve this objective, this Recommendation: + +- 1) indicates methods for measuring the optical signal degradation; +- 2) classifies those methods by type; +- 3) defines suitable optical parameters to detect optical signal degradation; and +- 4) describes the applications or conditions where these optical parameters can be relevant. + +This Recommendation refers to DWDM systems and ONEs with optical channels with bit rates up to approximately 10 Gbit/s using non-return to zero (NRZ) or return to zero (RZ) line coding and bit rates at approximately 40 Gbit/s and 100 Gbit/s using advanced modulation formats, such as (dual polarization) quadrature phase shift keying. Bit rates above 100 Gbit/s and systems employing other modulation formats are for further study. + +# 2 References + +## 2.1 Normative references + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.650.2] Recommendation ITU-T G.650.2 (2015), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable*. +- [ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*. +- [ITU-T G.653] Recommendation ITU-T G.653 (2010), *Characteristics of a dispersion-shifted single-mode optical fibre and cable*. +- [ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable*. +- [ITU-T G.663] Recommendation ITU-T G.663 (2011), *Application-related aspects of optical amplifier devices and subsystems*. +- [ITU-T G.664] Recommendation ITU-T G.664 (2012), *Optical safety procedures and requirements for optical transmission systems*. +- [ITU-T G.692] Recommendation ITU-T G.692 (2005), *Optical interfaces for multichannel systems with optical amplifiers*. + +- [ITU-T O.201] Recommendation ITU-T O.201 (2003), *Q-factor test equipment to estimate the transmission performance of optical channels*. +- [ITU-T X.805] Recommendation ITU-T X.805 (2003), *Security architecture for systems providing end-to-end communications*. + +# 3 Terms and definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following term defined in [ITU-T G.650.2]: + +- stimulated Brillouin scattering (SBS) + +This Recommendation uses the following terms defined in [ITU-T G.663]: + +- polarization mode dispersion (PMD) (1st and higher orders) +- four-wave mixing (FWM) +- amplified spontaneous emission (ASE) noise in optical amplification (OA) +- chromatic dispersion +- reflections (see reflectance) +- cross-phase modulation (XPM) +- self-phase modulation (SPM) +- stimulated Raman scattering (SRS) + +This Recommendation uses the following term defined in [ITU-T G.692]: + +- Frequency (or wavelength) deviation from nominal (see central frequency deviation) + +This Recommendation uses the following term defined in [ITU-T O.201]: + +- *Q*-factor + +This Recommendation uses the following terms defined in [b-ITU-T G-Sup.39]: + +- optical signal-to-noise ratio (OSNR) +- inter-channel crosstalk +- interferometric crosstalk + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 chromatic dispersion slope:** The slope of the curve of chromatic dispersion coefficient versus wavelength. + +**3.2.2 fully regenerated optical network:** Optical network where optical-electrical-optical conversion is performed in each network element using re-amplification, reshaping and retiming (3R) regeneration. + +**3.2.3 transparent optical network element:** An optical network element where there is no optical-electrical-optical conversion of the optical signal. + +# **4 Abbreviations and acronyms** + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|---------------------------------------------| +| 3R | Re-amplification, Reshaping and Retiming | +| ASE | Amplified Spontaneous Emission | +| BER | Bit Error Ratio | +| CWDM | Coarse Wavelength Division Multiplexing | +| DCM | Dispersion Compensation Module | +| Demux | Demultiplexer | +| DGD | Differential Group Delay | +| DSP | Digital Signal Processing | +| DWDM | Dense Wavelength Division Multiplexing | +| EME | Embedded Monitoring Equipment | +| EMP | External Monitoring Point | +| ESR | Errored Second Ratio | +| FEC | Forward Error Correction | +| FWM | Four-Wave Mixing | +| Mux | Multiplexer | +| NOC | Network Operations Centre | +| NRZ | Non-Return to Zero | +| OA | Optical Amplification | +| OADM | Optical Add-Drop Multiplexer | +| OD | Optical Demultiplexing | +| O/E | Optical to Electrical | +| OM | Optical Monitoring | +| ONE | Optical Network Element | +| OSA | Optical Spectrum Analyser | +| OSNR | Optical Signal-to-Noise Ratio | +| OTDR | Optical Time Domain Reflectometer | +| OTN | Optical Transport Network | +| PDL | Polarization-Dependent Loss | +| PMD | Polarization Mode Dispersion | +| ROADM | Reconfigurable Optical Add-Drop Multiplexer | +| RZ | Return to Zero | +| SBS | Stimulated Brillouin Scattering | +| SDH | Synchronous Digital Hierarchy | + +| | | +|------|-------------------------------| +| SESR | Severely Errored Second Ratio | +| SLA | Service Level Agreement | +| SPM | Self-Phase Modulation | +| SRS | Stimulated Raman Scattering | +| XPM | cross-Phase Modulation | + +# 5 Optical monitoring overview + +The management of existing synchronous digital hierarchy (SDH) networks relies on monitoring digital parameters such as bit error ratio (BER), errored second ratio (ESR) and severely errored second ratio (SESR), which are measured at the electrical layer (at 3R regenerators), as described in [b-ITU-T G.826]. + +A similar approach is used in the optical transport network (OTN), using ITU-T G.709 framing, for monitoring the end-to-end connections and the optical connections at the electrical level. + +While these methods give a reliable measure of the end-to-end performance of an optical channel, they cannot be applied inside a transparent optical domain where no 3R regenerators are available to terminate the frame overhead. Therefore, they may not provide sufficient information to isolate the root cause of problems in complex DWDM networks. + +Moreover, the rapid progress in optical technology is leading to ever-increasing channel counts and transmission speeds and to longer all-optical connections inside an optical domain. + +This leads to the increasing influence of linear and non-linear distortions, which makes system commissioning an increasingly complex task. + +An optimum solution for an OTN combines: + +- proper network design to limit noise sources, dispersion and intermodulation effects; +- suitable alarms for the active optical components and the optical fibre links within the network for fault detection and isolation; +- the use of appropriate OM throughout the network to monitor the most critical optical parameters. + +Individually, these three actions cannot guarantee a suitable optical quality but, when combined, they provide a suitable solution for the management of OTNs. + +An appropriate level of OM gives some visibility inside optical networks ensuring that channel paths are properly configured and optical parameters are appropriate for reliable service delivery. The collection of OM data in a network operations centre (NOC) makes the management of complex DWDM networks easier. + +The objectives of OM are to detect anomalies, defects, degradations and faults affecting the quality of the optical layer. The optical parameters to be monitored should be established and defined according to specific requirements. + +The ability to improve end-to-end monitoring with distributed OM may have both reliability and cost benefits for configuration management and fault/degradation management, since some defects, degradations and faults affecting the quality of the optical layer are more easily detected and isolated through OM. + +Aging effects, changes in noise due to changes in the temperature and humidity, are impairments that can seriously degrade the quality of the signal transmission. OM makes it possible to detect these degradations in a reliable way. + +OM is a proactive process that can help to manage service level agreements (SLAs) and to mitigate operational costs (although often at the expense of increased equipment costs). OM is increasingly important in the maintenance of a high degree of equipment reliability, coupled with the ability to diagnose degradations and failures quickly, and locate and repair network problems. The technique is also becoming more and more challenging as network complexity increases. + +OM is an important complement to the monitoring techniques applied at the digital client layers of the optical layer network. + +OM is a key element in the management of the optical networks, since it is possible to manage only what it is possible to measure. + +While OM is implemented (and in service) in many current optical transmission systems, there are significant differences in OM requirements between them. This is due to the presence of different transmission and control system designs, and different strategies for impairment management in the various systems. For this reason, a general requirement for a set of parameters with a defined accuracy as a reliable indicator of the operational condition of such a system cannot be generalized. Even within a single system, the parameters that are of importance may vary between different network elements and the monitoring requirements, even for internal control, are different for the various network elements. Consequently, a general requirement for supervision of particular parameters will normally lead to a sub-optimal (and, therefore, non-cost-effective) solution. An appropriate optical supervision scheme will, for this reason, always be related to the particular transmission and control system design, engineering rules and implementation of impairment management of such a system. However, based on what is feasible from the technological point of view and on what network operators need, some monitoring choices can be identified, as outlined in this Recommendation. + +# **6 Classification of monitoring methods** + +Clauses 6.1 to 6.6 describe two different forms of signal monitoring, namely time domain and frequency domain methods, and explain the differences between signal monitoring and equipment monitoring, as well as the differences between embedded and external monitoring devices. + +## **6.1 Signal monitoring** + +This Recommendation is limited to non-intrusive measurements that allow in-service monitoring of the optical signal quality. + +The measurements defined in this Recommendation do not measure every single impairment listed in Table 1 for up to 10 Gbit/s systems or Table 2 for 40 Gbit/s and 100 Gbit/s systems, but rather the effect of these impairments on the parameters that can be measured. + +A distinction between frequency and time domain measurement methods can be made. + +### **6.1.1 Time domain methods** + +Methods which analyse the behaviour of the optical signal in the time domain tend to be closer to the full BER measurement than those in the frequency domain. These methods are sensitive to both noise and distortion effects. Sampling oscilloscopes and *Q*-factor metres, as described in [b-ITU-T O.201], are representative of sampling methods (synchronous methods). However, time domain methods generally need optical demultiplexing (OD), optical to electrical conversion and, in the case of sampling methods, synchronization to the bit rate. Also, the difference in the characteristics of the reference receiver compared to the system receiver and the effect of residual dispersion at the measurement point, as discussed in clause III.2, has to be considered. + +NOTE – The above description of sampling oscilloscopes and *Q*-factor metres is for up to 10 Gbit/s NRZ or RZ signals. Sampling oscilloscope and *Q*-factor measurements may not provide useful results for 40 Gbit/s or 100 Gbit/s signals with advanced modulation formats. + +### 6.1.2 Frequency (or wavelength) domain methods + +Frequency/wavelength domain methods of OM analyse the spectral characteristics of the optical signal. These spectral methods have in common that they do not sample the signal or synchronize to it, thereby eliminating the entire reference receiver. Typically, they employ a spectrum analyser device, which may be of varying resolution, and may or may not sense all channels simultaneously. + +The simplest form of a spectral analysis is simple power monitoring of each channel. This can be done with, for example, a diffraction grating and detector array to sense all of the channel powers simultaneously. At the expense of an increase in the complexity and resolution, this method can also be extended to look at the precise shape of the signal spectrum. + +The fundamental property of these spectral methods is that they are averaging methods that, by definition, do not sense the pulse distortion. This means that quality monitoring by spectral methods will be insensitive to all of the effects due to distortions. + +## 6.2 Equipment monitoring (indirect methods) + +Indirect methods make use of an empirical correlation between equipment failures and signal quality. Equipment failures, such as power supply failures and laser temperature, may be detected by built-in self-test functions. These indicators are likely to be very system and implementation dependent. + +Indirect methods mainly indicate that the system is operating, and it is assumed that the signal quality is also degraded, when an equipment parameter is outside the specified range. + +However, a correct equipment parameter is no guarantee of signal integrity, since there may be other impairments that affect the signal quality (e.g., fibre attenuation). + +## 6.3 Fibre link monitoring + +An optical time domain reflectometer (OTDR), which may be embedded, can detect and locate fibre link failures, such as fibre cut and abnormal attenuation. Fibre link monitoring indicates the current state of fibre link, and can be used to detect and to isolate fibre link faults. However, a normal fibre link status is no guarantee of signal integrity, since there may be other impairments that affect the signal quality. + +## 6.4 Monitoring based on received signals + +Coherent receivers are commonly used in 40 Gbit/s and 100 Gbit/s systems using advanced modulation formats. Digital signal processing (DSP) in coherent receivers may include chromatic dispersion compensation, nonlinear compensation, polarization equalization, and forward error correction (FEC) processing. From these processing steps, parameters can be extracted that provide information on the transmission quality of the optical path (transmitter to receiver) of the received channel. Some optical impairments, such as chromatic dispersion and differential group delay, could be estimated from the DSP. However, chromatic dispersion or differential group delay are not expected to be likely faults in a DWDM network using coherent receivers. + +## 6.5 Embedded monitoring equipment + +Embedded monitoring equipment (EME) is usually tightly integrated with the management functions of an optical network element (ONE). For cost reasons, embedded monitoring is usually limited to a few basic parameters. + +Different monitoring points placed in the same network element can share the EME. + +### **6.5.1 Embedded monitoring equipment accuracy** + +It is desirable that the accuracy of embedded monitoring devices is sufficiently high to provide meaningful input for automated management decisions, should any be defined. This can often be achieved with relatively low effort compared to a general purpose test instrument since, in many cases, only the deviation from a known nominal value is of interest, and the normal operating range of network elements is narrow. + +## **6.6 External monitoring equipment** + +External monitoring equipment typically serves a different purpose than EME. It is normally used to measure additional, more sophisticated performance parameters or when a more accurate value of certain performance parameters is required. + +The main applications are the location of hard-to-find failures that cannot be isolated by the embedded monitoring devices, as well as function tests and accurate parameter measurements during installation, commissioning or repair. + +In contrast to EME, external monitoring instruments are usually not permanently installed, but rather connected on-demand to critical network segments and used in an interactive mode, often remote controlled from an NOC. + +### **6.6.1 External monitoring equipment accuracy** + +External monitoring equipment generally has higher accuracy and a wider measurement range than embedded monitoring devices, since it must provide reliable absolute measurements over the full operating range of an optical transmission system and the higher cost implied by this can be shared over a large number of ONEs. + +# **7 Optical impairments** + +This clause lists and categorizes the main systems impairments at the optical layer that limit the capacity of the system to transport information. + +Lists of the possible main system impairments are given in Table 1 for up to 10 Gbit/s systems using NRZ or RZ line coding, and in Table 2 for 40 Gbit/s and 100 Gbit/s coherent systems using advanced modulation formats, respectively. + +**Table 1 – Optical impairments in up to 10 Gbit/s systems using non-return to zero or return to zero line coding** + +| Variation of the impairment | Relative frequency of occurrence | Description | +|--------------------------------------------------------------------------|-----------------------------------------|--------------------------------------------------------------| +| Attenuation | High | | +| Optical channel power changes due to gain variations | High | | +| Frequency (or wavelength) deviation from nominal | High | [ITU-T G.692] | +| Polarization mode dispersion (PMD) (1st and higher orders) | Medium | Appendix II of [ITU-T G.663] | +| Four-wave mixing (FWM) | Medium | Appendix II of [ITU-T G.663] | +| Amplified spontaneous emission (ASE) noise in optical amplification (OA) | Medium | Appendix II of [ITU-T G.663] | +| Chromatic dispersion | Medium | Appendix II of [ITU-T G.663] | +| Chromatic dispersion slope | Medium | [ITU-T G.652], [ITU-T G.653], [ITU-T G.655] | +| Reflections | Medium | Appendix III of [ITU-T G.663] | +| Laser noise | Medium | | +| Inter-channel crosstalk | Medium | [b-ITU-T G-Sup.39] | +| Interferometric crosstalk | Medium | [b-ITU-T G-Sup.39] | +| Cross-phase modulation (XPM) | Low | Appendix II of [ITU-T G.663] | +| Self-phase modulation (SPM) | Low | Appendix II of [ITU-T G.663] | +| Stimulated Brillouin scattering (SBS) | Low | Appendix II of [ITU-T G.650.2], Appendix II of [ITU-T G.663] | +| Stimulated Raman scattering (SRS) | Low | Appendix II of [ITU-T G.663] | + +**Table 2 – Optical impairments in 40 Gbit/s and 100 Gbit/s coherent systems using advanced modulation formats** + +| Variation of the impairment | Relative frequency of occurrence | Description | +|------------------------------------------------------------|-----------------------------------------|------------------------------| +| Attenuation | High | | +| Optical channel power changes due to gain variations | High | | +| Frequency (or wavelength) deviation from nominal | High | [ITU-T G.692] | +| Polarization mode dispersion (PMD) (1st and higher orders) | Low | Appendix II of [ITU-T G.663] | +| Four-wave mixing (FWM) | Medium | Appendix II of [ITU-T G.663] | + +**Table 2 – Optical impairments in 40 Gbit/s and 100 Gbit/s coherent systems using advanced modulation formats** + +| Variation of the impairment | Relative frequency of occurrence | Description | +|--------------------------------------------------------------------------|----------------------------------|--------------------------------------------------------------| +| Amplified spontaneous emission (ASE) noise in optical amplification (OA) | Medium | Appendix II of [ITU-T G.663] | +| Chromatic dispersion | Low | Appendix II of [ITU-T G.663] | +| Chromatic dispersion slope | Low | [ITU-T G.652], [ITU-T G.653], [ITU-T G.655] | +| Reflections | Medium | Appendix III of [ITU-T G.663] | +| Laser noise | Medium | | +| Inter-channel crosstalk | Medium | [b-ITU-T G-Sup.39] | +| Interferometric crosstalk | Medium | [b-ITU-T G-Sup.39] | +| Cross-phase modulation (XPM) | Low | Appendix II of [ITU-T G.663] | +| Self-phase modulation (SPM) | Low | Appendix II of [ITU-T G.663] | +| Cross-polarization modulation (XPolM) | Low | Appendix II of [ITU-T G.663] | +| Stimulated Brillouin scattering (SBS) | Low | Appendix II of [ITU-T G.650.2], Appendix II of [ITU-T G.663] | +| Stimulated Raman scattering (SRS) | Low | Appendix II of [ITU-T G.663] | + +All these impairments are capable of being severe enough to cause severe degradation of an optical signal up to a level where the receiver is no longer able to detect the data with a reasonable error ratio. For any of the impairments, there exists a curve of penalty versus the probability of occurrence per unit time (see Appendix I). + +The levels of relative frequency of occurrence in Table 1 and Table 2 are as follows. + +- Low: When the probability of the effect being severe enough to cause a penalty of $x$ dB is $\sim 1$ event per 10 years. +- Medium: When the probability of the effect being severe enough to cause a penalty of $x$ dB is $\sim 1$ event per year. +- High: When the probability of the effect being severe enough to cause a penalty of $x$ dB is $\sim 10$ events per year. + +NOTE 1 – The figures in the preceding paragraph refer to the steady state period of the life of the systems. An event could cause $x$ dB penalty on a single optical channel, or on a multichannel system. Indicative values for $x$ dB penalty are given in Appendix II. + +NOTE 2 – The relative frequency of occurrence of the optical impairments given in Table 1 refers to optical signals with bit rates up to approximately 10 Gbit/s, and that in Table 2 refers to optical signals with bit rates of approximately 40 Gbit/s and 100 Gbit/s for advanced modulation formats. Impairments for optical signals with bit rates higher than 100 Gbit/s are for further study. + +# 8 Optical monitoring parameters + +The list of the optical parameters that can be measured using current technology in optical transmission systems is: + +- channel power; +- total power; + +- OSNR when no significant noise shaping is present; +- channel wavelength; +- *Q*-factor. + +Appendix III contains information about the performance obtainable from currently available monitoring technology. + +# 9 Correlation between impairment effects and optical monitoring parameters degradation + +See Table 3. + +**Table 3 – List of correlation between the underlined impairments and monitoring parameters** + +| Parameters | Total power | Channel power | Channel wavelength | Optical signal-to-noise ratio | Q -factor | +|------------------------------------------------------|-------------|---------------|--------------------|-------------------------------|------------------| +| Variation of attenuation | × | × | | × | × | +| Frequency (or wavelength) deviation from nominal | | × | × | × | × | +| Optical channel power changes due to gain variations | | × | | × | × | + +## 9.1 Variation of attenuation + +For further study. + +## 9.2 Frequency (or wavelength) deviation from nominal + +There is a direct correlation between the impairment of "frequency deviation from nominal" and the OM parameter "channel wavelength". The required measurement accuracy for the channel wavelength depends upon the "maximum central frequency deviation" for the channel. [ITU-T G.692] gives a value for this parameter of $n/5$ (where $n$ is the channel spacing) for applications with channel spacing of 200 GHz and above, but no value is given for channel spacing below this. + +## 9.3 Optical channel power changes due to gain variations + +There is a direct correlation between the impairment "optical channel power changes due to gain variations" and the OM parameter "channel power". For slow variations in channel gain, optical channel power monitoring will provide adequate information to establish the location of the gain variation. However, DWDM systems may involve many built-in control loops, such as laser wavelength tuning and output power control, channel equalization power control, amplifier gain control and transient control and channel receiver power and dispersion controls, to maintain end-to-end transmission performance. These control loops may operate over millisecond or even microsecond timescales and will respond to or even create sub-second photonic events that may impact end-to-end transmission quality. Since it is not practical to monitor channel power with a time granularity sufficiently small to capture these events, it is helpful to acquire the maximum and minimum of control function input and output parameters within a coarser time granularity. + +# **10 Applications** + +In DWDM systems, OM could help in the following activities: + +- i) configuration management for system and channel activation, addition of new channels, etc.; +- ii) fault management to detect and to isolate faults; +- iii) degradation management in order to keep the system running and to detect degradations before a fault occurs. + +In order to achieve the above objectives, one or more of the following monitoring choices could be considered for internal monitoring in DWDM systems with the resulting data available both locally and from a remote location. The choice of which option to include depends upon the specific characteristics of the DWDM system (e.g., length, number of spans, number of channels, inaccessibility of the sites) as well as cost/benefit considerations: + +- a) total power at input of various stages of OA; +- b) total power at output of various stages of OA; +- c) channel power at the DWDM transmitter output before the multiplexer (mux); +- d) channel power at the DWDM receiver input after the demultiplexer (demux); +- e) channel power at the output of various stages of OA; +- f) channel OSNR at the output of various stages of OA; +- g) channel wavelength deviation at least at one point along the optical path. + +A tap at the output of the various stages of OA enables a more detailed analysis of the optical channel status to be performed via external measurement equipment. Whether to include this tap depends upon the specific characteristics of the DWDM system as well as cost/benefit considerations. + +# **11 Optical safety considerations** + +See [ITU-T G.664] for optical safety considerations. + +# **12 Security considerations** + +EMPs might be exposed to malicious or inadvertent access and appropriate actions may be necessary to keep them secure. Security aspects relevant to the OM of DWDM systems may include, but are not limited to, communication security, non-repudiation, access control, availability and data integrity as described in [ITU-T X.805]. The description of the appropriate actions is considered to be outside the scope of this Recommendation. + +# Appendix I + +## Severity of optical impairments + +(This appendix does not form an integral part of this Recommendation.) + +The optical impairments listed in Table 1 and Table 2 are all capable of causing severe degradation of an optical signal to the point of failure of the receiver to be able to detect the data with a reasonable error ratio. For any of the impairments, it is possible to plot a curve of penalty versus occurrence rate (the probability of occurrence per time). An example curve in the case of attenuation might take the form of the curve in Figure I.1. + +![Figure I.1: Example curve of penalty versus occurrence rate due to attenuation variation. The graph shows LOG occurrence rate on the y-axis and Penalty on the x-axis. The curve starts high on the y-axis and decreases sharply, then levels off. Three regions are labeled: 'Small penalty with high probability' at the top left, 'Medium penalty with medium probability' in the middle, and 'High penalty with low probability' at the bottom right. The label G.697(09)_Fl.1 is at the bottom right of the graph.](ef25c3cf1fdb334fc8679e85ab5265ca_img.jpg) + +Figure I.1 is a line graph showing the relationship between LOG occurrence rate (y-axis) and Penalty (x-axis) for attenuation variation. The curve starts at a high LOG occurrence rate for low penalty and decreases rapidly, then levels off into a plateau. Three specific points on the curve are highlighted with arrows and labels: 'Small penalty with high probability' points to the initial steep drop, 'Medium penalty with medium probability' points to the middle section, and 'High penalty with low probability' points to the final plateau. The graph is labeled G.697(09)\_Fl.1. + +Figure I.1: Example curve of penalty versus occurrence rate due to attenuation variation. The graph shows LOG occurrence rate on the y-axis and Penalty on the x-axis. The curve starts high on the y-axis and decreases sharply, then levels off. Three regions are labeled: 'Small penalty with high probability' at the top left, 'Medium penalty with medium probability' in the middle, and 'High penalty with low probability' at the bottom right. The label G.697(09)\_Fl.1 is at the bottom right of the graph. + +**Figure I.1 – Example curve of penalty versus occurrence rate due to attenuation variation** + +The shape of the curve and the probability levels will, of course, be different for each of the impairments on the list. On the curve for attenuation, small impairments of the order of 0.1 dB being very probable and large impairments (for example, 6 dB or greater) being very much less probable. The curve for a different impairment will have a different shape. For example, SBS might look like the curve in Figure I.2. + +![Figure I.2: Example curve of penalty versus occurrence rate due to stimulated Brillouin scattering variation. The graph shows LOG occurrence rate on the y-axis and Penalty on the x-axis. The curve is relatively flat and low on the y-axis, with a slight downward slope at the end. A label 'High penalty with low probability' points to this final downward slope. The label G.697(09)_Fl.2 is at the bottom right of the graph.](dc0cec98faa3ead994c1b171cb56265d_img.jpg) + +Figure I.2 is a line graph showing the relationship between LOG occurrence rate (y-axis) and Penalty (x-axis) for stimulated Brillouin scattering variation. The curve is nearly horizontal and low on the y-axis for most of the x-axis range, with a slight downward slope at the far right. An arrow labeled 'High penalty with low probability' points to this final downward slope. The graph is labeled G.697(09)\_Fl.2. + +Figure I.2: Example curve of penalty versus occurrence rate due to stimulated Brillouin scattering variation. The graph shows LOG occurrence rate on the y-axis and Penalty on the x-axis. The curve is relatively flat and low on the y-axis, with a slight downward slope at the end. A label 'High penalty with low probability' points to this final downward slope. The label G.697(09)\_Fl.2 is at the bottom right of the graph. + +**Figure I.2 – Example curve of penalty versus occurrence rate due to stimulated Brillouin scattering variation** + +Here, the occurrence rate is very low (failure of the dither circuit or very much higher power in the fibre than expected) but the penalty generated can be very severe. + +Since this is the case, the approach that has been taken within this Recommendation is to define an approximate penalty that is considered as constituting a significant impairment (e.g., 3 dB) and then give an indication of the frequency with which this occurs in a typical optical network. + +## **Appendix II** + +## **Penalty severity value X** + +(This appendix does not form an integral part of this Recommendation.) + +One operator, referring to a 10 000 km DWDM network, suggests defining the *x* value equal to a 3 dB penalty as a figure that constitutes a significant impairment. + +# Appendix III + +## Optical monitoring performance + +(This appendix does not form an integral part of this Recommendation.) + +This appendix contains information concerning the performance obtainable from currently available OM technology. This information should not be interpreted as a requirement or specification, but is intended to help in identifying those cases where a particular desired OM performance requirement can (or cannot) be met using currently available technology. Requirements for OM performance can only be generated with respect to a particular function and for a particular system design and, in most cases, practical and cost-effective specifications for any individual monitoring solution may be very different from the data given in Tables III.1 to III.4. + +Table III.1 gives information on the standard measurement performance that might be obtainable with low-cost measurement equipment embedded in the ONEs at the DWDM receiver input. Table III.2 gives information on the standard measurement performance that might be obtainable with low-cost measurement equipment embedded in the ONEs at multichannel points where there is no requirement to measure OSNR. Table III.3 gives the same information for low-cost measurement equipment embedded in the ONEs that can measure OSNR. Table III.4 gives measurement performance for premium measurement equipment with costs appropriate to measurements in a much-reduced number of places in the network by the maintenance staff. + +**Table III.1 – Performance of embedded optical monitoring at the dense wavelength division multiplexing receiver input** + +| Parameter | Accuracy | Repeatability | Measurement range | +|---------------|----------------|---------------|-----------------------------------| +| Channel power | ±2 dB (Note 1) | ±0.5 dB | Receiver operating range (Note 2) | + +NOTE 1 – Since this function must be performed within every DWDM receiver, it must be very simple to remain cost effective and, for this reason, this value is relaxed compared to the value in Table III.2. +NOTE 2 – The input power range over which the receiver would normally be expected to operate. + +**Table III.2 – Performance of embedded optical monitoring without optical signal-to-noise ratio** + +| Parameter | Accuracy | Repeatability | Measurement range | +|---------------|----------------|---------------|--------------------------------------| +| Total power | ±1 dB (Note 1) | ±0.5 dB | (-60 to +5) + tap loss dBm (Note 2) | +| Channel power | ±1 dB (Note 1) | ±0.5 dB | (-60 to -10) + tap loss dBm (Note 2) | + +NOTE 1 – This value includes contributions from both measurement uncertainty and tap loss variation. In some systems, the tap loss variation may lead to worse accuracy than this, although this may be compensated by calibration (with additional cost). +NOTE 2 – Since different systems use monitoring taps with different splitting fractions (e.g., 5% or 2%), the measurement range is shown at the output of the tap. To derive the measurement range, the tap loss must be added to the values. For example, a 2% tap would make the values 17 dB higher. + +**Table III.3 – Performance of embedded optical monitoring with optical signal-to-noise ratio** + +| Parameter | Accuracy | Repeatability | Measurement range | +|----------------------------------------------------------------------------------|----------------|---------------|--------------------------------------------------------------------------------------------------------------------| +| Total power | ±1 dB (Note 1) | | | +| Channel power | ±1 dB (Note 1) | ±0.5 dB | (-40 to -10) + tap loss dBm (Note 2) | +| Channel wavelength | ±75 pm | | | +| OSNR where no significant noise shaping is present (in 0.1 nm optical bandwidth) | ±1.5 dB | ±0.5 dB | For channel power ≥25 dBm
OSNR 10 to 30 dB for ≥100 GHz spacing
OSNR 10 to 25 dB for 50 GHz spacing (Note 3) | + +NOTE 1 – This value includes contributions from both measurement uncertainty and tap loss variation. In some systems, the tap loss variation may lead to worse accuracy than this, although this may be compensated by calibration (with additional cost). + +NOTE 2 – Since different systems use monitoring taps with different splitting fractions (e.g., 5% or 2%), the measurement range is shown at the output of the tap. To derive the measurement range, the tap loss must be added to the values. For example, a 2% tap would make the values 17 dB higher. + +NOTE 3 – This measurement range may not be obtainable if there is significant spectral broadening due to non-linear effects in the link. + +**Table III.4 – Performance of premium optical monitoring equipment** + +| Parameter | Accuracy | Repeatability | Measurement range | +|----------------------------------------------------------------------------------|----------------------------------------|---------------|--------------------------------------------------------------------------| +| Total power | ±0.2 dB (Note 1) | | | +| Channel power | ±0.4 dB (Note 1) | ±0.2 dB | (-80 to +23) + tap loss dBm (Note 2) | +| Channel wavelength | ±0.5 pm | | | +| OSNR where no significant noise shaping is present (in 0.1 nm optical bandwidth) | ±0.4 dB OSNR < 20
±0.7 dB OSNR < 30 | | 0 to 42 dB for 100 GHz spacing
0 to 28 dB for 50 GHz spacing (Note 3) | +| Q-factor | ±10% | ±5% | 4 to 14 | +| Others | | | | + +NOTE 1 – This value does not include any contribution from tap loss variation, which would have to be compensated by calibration. + +NOTE 2 – Since different systems use monitoring taps with different splitting fractions (e.g., 5% or 2%), the measurement range is shown at the output of the tap. To derive the measurement range, the tap loss must be added to the values. For example, a 2% tap would make the values 17 dB higher. + +NOTE 3 – This measurement range may not be obtainable if there is significant spectral broadening due to non-linear effects. + +## III.1 Optical signal-to-noise ratio measurement + +OSNR measurement currently uses the principle of measuring the noise between channels in order to estimate the noise at the channel wavelength. See Figure III.1. + +![Figure III.1: Optical signal-to-noise ratio measurement method graph.](9b5411fa2d169b66f6185fbf67b49766_img.jpg) + +A graph showing Power on the y-axis and Wavelength on the x-axis. It displays three optical channels as purple peaks. The central peak is labeled $P_i + N_i$ at its top. The noise level between the channels is indicated by three red 'x' marks: one at the center of the main channel labeled $N_i$ , and two on the adjacent channels labeled $N(v_i - \Delta v)$ and $N(v_i + \Delta v)$ . The text 'G.697(09)\_FIII.1' is in the bottom right corner. + +Figure III.1: Optical signal-to-noise ratio measurement method graph. + +**Figure III.1 – Optical signal-to-noise ratio measurement method** + +This method works well for simple point-to-point systems with nothing but fibre and amplifiers in the optical path. For more complex DWDM systems, however, the introduction of any element which causes shaping of the noise between channels renders this method inaccurate. + +In the section of a DWDM system illustrated in Figure III.2, for example, there is a simple optical add-drop multiplexer (OADM), which is configured to drop and add a single channel. + +![Figure III.2: Section of a dense wavelength division multiplexing system with an optical add-drop multiplexer.](ab846b81e78dbc8da2a6f9511e2f248a_img.jpg) + +A schematic diagram of an optical path. From left to right, it consists of an amplifier (triangle), two optical isolators (circles), another amplifier, and an optical add-drop multiplexer (OADM) represented by a box with multiple horizontal lines. Two green square icons representing optical transceivers are connected to the OADM. Point A is marked with a blue arrow above the OADM input, and point B is marked with a blue arrow below the OADM output. The text 'G.697(09)\_FIII.2' is in the bottom right corner. + +Figure III.2: Section of a dense wavelength division multiplexing system with an optical add-drop multiplexer. + +**Figure III.2 – Section of a dense wavelength division multiplexing system with an optical add-drop multiplexer** + +The optical spectra that might be found at points marked A and B are shown in Figures III.3 and III.4, respectively. + +As can be seen from Figure III.3, at point A the method of OSNR measurement illustrated in Figure III.1 gives accurate results as the variation in noise with wavelength is fairly slow. + +NOTE – Channel 3 of this hypothetical 10-channel system is not present. + +![Figure III.3: Optical spectrum at point A. The plot shows a series of sharp, narrow peaks representing optical channels, spaced evenly across the wavelength range from 1542 nm to 1560 nm. The power level of the peaks is approximately -5 dB, and the noise floor between the channels is relatively flat and low, around -25 dB. The x-axis is labeled from 1542 to 1560 nm in 2 nm increments. The y-axis is labeled from 0 to -45 dB in 5 dB increments. A small label 'G.697(09)_FIII.3' is visible in the bottom right corner of the plot area.](9ce50bc10864dc86e1cdee4be08f1897_img.jpg) + +Figure III.3: Optical spectrum at point A. The plot shows a series of sharp, narrow peaks representing optical channels, spaced evenly across the wavelength range from 1542 nm to 1560 nm. The power level of the peaks is approximately -5 dB, and the noise floor between the channels is relatively flat and low, around -25 dB. The x-axis is labeled from 1542 to 1560 nm in 2 nm increments. The y-axis is labeled from 0 to -45 dB in 5 dB increments. A small label 'G.697(09)\_FIII.3' is visible in the bottom right corner of the plot area. + +**Figure III.3 – Optical spectrum at point A** + +Figure III.4 shows the spectrum after the mux of the OADM and a booster amplifier. Here, the situation is radically different. The noise between the channels has been strongly shaped by the combined filtering function of the demux/mux. As can be seen by the noise peak at the wavelength of the missing channel in this example, there is about 15 dB more noise at the channel wavelengths than at the mid-points between channels and, hence, the OSNR estimate at this point is about 15 dB optimistic. For the wavelength that has been added, however, we have the reverse situation and the noise level at the mid-points is much higher than the noise added at the channel wavelength. The OSNR estimate for this channel is, therefore, seriously pessimistic. + +[b-IEC 61280-2-9] could be a useful reference for additional information on OSNR measurements. + +![Figure III.4: Optical spectrum at point B. The plot shows the same optical channels as Figure III.3, but the noise floor is significantly more complex. The noise is shaped by filtering, resulting in a periodic pattern of peaks and valleys. The noise peaks occur at the channel wavelengths (around -25 dB) and the noise valleys occur at the mid-points between channels (around -40 dB). This indicates a 15 dB difference in noise level between channel and mid-point. The axes and labels are identical to Figure III.3, with a small label 'G.697(09)_FIII.4' in the bottom right corner.](06ccd604e7eac77c7a5a323b6a913f15_img.jpg) + +Figure III.4: Optical spectrum at point B. The plot shows the same optical channels as Figure III.3, but the noise floor is significantly more complex. The noise is shaped by filtering, resulting in a periodic pattern of peaks and valleys. The noise peaks occur at the channel wavelengths (around -25 dB) and the noise valleys occur at the mid-points between channels (around -40 dB). This indicates a 15 dB difference in noise level between channel and mid-point. The axes and labels are identical to Figure III.3, with a small label 'G.697(09)\_FIII.4' in the bottom right corner. + +**Figure III.4 – Optical spectrum at point B** + +For a realistic OSNR measurement in the presence of noise shaping, it is essential to measure the filtered noise value in the passband of the optical filters in a system (often called "in-band" OSNR measurement). Three methods of achieving this are described in clauses III.1.1 to III.1.4. + +#### III.1.1 Narrow-band optical spectrum analyser method + +If the signal spectrum does not occupy the full channel bandwidth and the optical filter shape has a flat region, the OSNR can be measured with a narrow-band optical spectrum analyser (OSA). An example of this is shown in Figure III.5 for the case of a 10 Gbit/s signal in a 100 GHz channel spacing system. Here, the OSNR can be estimated by measuring the signal power and the noise in the flat region away from the signal. Care must be taken to measure the signal with a sufficiently large resolution bandwidth to capture all of the signal power, while measuring the noise with a small enough resolution bandwidth to exclude the signal. This may require a different resolution bandwidth for each part of the measurement and for the noise power to be scaled from the measurement bandwidth to the usual reference value of 0.1 nm. + +![Figure III.5: Optical spectrum plot showing a signal peak and noise floor.](a1545557e366b6302109d13360b199c3_img.jpg) + +The figure is a line graph representing an optical spectrum. The vertical axis (y-axis) represents power in dB, ranging from -45 to 0 in increments of 5. The horizontal axis (x-axis) represents wavelength in nm, ranging from 1549.5 to 1550.5 in increments of 0.2. A purple curve shows the spectrum. It features a broad, relatively flat noise floor between approximately 1549.5 nm and 1550.5 nm, with a power level around -30 dB. A sharp, narrow peak labeled 'Signal' is centered at approximately 1549.95 nm, reaching a power level of 0 dB. Two arrows labeled 'Noise' point to the flat regions on either side of the signal peak, indicating where the noise power should be measured. The text 'G.697(12)\_FIII.5' is located at the bottom right of the plot area. + +Figure III.5: Optical spectrum plot showing a signal peak and noise floor. + +**Figure III.5 – Optical spectrum where signal does not occupy full channel bandwidth** + +However, as the baud rate becomes comparable with the channel spacing, the signal spectrum completely overlaps with the noise floor as illustrated in Figure III.6. In this case, a different measurement principle is required. Also, if the signal traverses multiple optical filters, the combined filter function becomes progressively less flat topped, thereby making accurate determination of the noise level more difficult. + +![Figure III.6: Optical spectrum plot showing power (dB) versus wavelength (nm). The x-axis ranges from 1549.5 to 1550.5 nm with major ticks every 0.2 nm. The y-axis ranges from -45 to 0 dB with major ticks every 5 dB. The spectrum shows a broad signal peak centered around 1549.9 nm, reaching a maximum power of approximately -10 dB. The signal occupies the full channel bandwidth from approximately 1549.7 nm to 1550.3 nm. A small label 'G.697(12)_FIII.6' is present at the bottom right of the plot area.](97f61e67792478fb6ce089868e503063_img.jpg) + +Figure III.6: Optical spectrum plot showing power (dB) versus wavelength (nm). The x-axis ranges from 1549.5 to 1550.5 nm with major ticks every 0.2 nm. The y-axis ranges from -45 to 0 dB with major ticks every 5 dB. The spectrum shows a broad signal peak centered around 1549.9 nm, reaching a maximum power of approximately -10 dB. The signal occupies the full channel bandwidth from approximately 1549.7 nm to 1550.3 nm. A small label 'G.697(12)\_FIII.6' is present at the bottom right of the plot area. + +**Figure III.6 – Optical spectrum where signal occupies full channel bandwidth** + +#### III.1.2 Time domain extinction measurement + +In this method, the signal for the channel to be measured is gated on and off at the entry point into the optical system using an acoustic-optical switch. The signal at the point to be measured is then sampled using a second switch, either in phase to measure the signal or out of phase to measure the noise power. This method requires fast high-extinction acoustic-optical switches or a gated OSA. The average signal level of the channel being measured is kept the same as during normal operation to maintain the operating point of the amplifiers. + +Obvious drawbacks of this method of measurement are that it requires equipment to be inserted at multiple points in the system and that it cannot be used to measure OSNR while the channel is in service. + +#### III.1.3 Polarization extinction measurement + +An alternative method of separating the signal from the noise is to exploit the fact that, to a first approximation, the optical transmission signal is polarized, whereas the ASE noise is unpolarized. In its simplest form, a combination of a variable polarization controller and a polarization beam splitter/filter is used to separate the polarized signal from the unpolarized noise as shown in Figure III.7. + +![Figure III.7: Polarization extinction method block diagram. The input 'Signal + ASE' enters a 'Polarization controller'. The output of the controller enters a 'Polarization beam splitter'. The beam splitter has two output branches. The upper branch is labeled 'Signal + ASE/2' and shows a spectrum plot. The lower branch is labeled 'ASE/2' and also shows a spectrum plot. Both branches enter separate photodetectors (represented by triangles with a horizontal line). The outputs of the photodetectors are fed into a 'Signal processing' block, which outputs the final result 'OSNR'. A dashed line encloses the 'Polarization beam splitter', the two photodetectors, and the 'Signal processing' block. A small label 'G.697(12)_FIII.7' is present at the bottom right of the diagram.](20136850feb70fd71c7d41cdae203ebb_img.jpg) + +Figure III.7: Polarization extinction method block diagram. The input 'Signal + ASE' enters a 'Polarization controller'. The output of the controller enters a 'Polarization beam splitter'. The beam splitter has two output branches. The upper branch is labeled 'Signal + ASE/2' and shows a spectrum plot. The lower branch is labeled 'ASE/2' and also shows a spectrum plot. Both branches enter separate photodetectors (represented by triangles with a horizontal line). The outputs of the photodetectors are fed into a 'Signal processing' block, which outputs the final result 'OSNR'. A dashed line encloses the 'Polarization beam splitter', the two photodetectors, and the 'Signal processing' block. A small label 'G.697(12)\_FIII.7' is present at the bottom right of the diagram. + +**Figure III.7 – Polarization extinction method block diagram** + +By variation of the polarization controller in front of the polarization beam splitter, it is possible to suppress the polarized signal and get access to the non-polarized in-band noise at one branch, where the other branch shows the signal plus noise [b-Rasztovits-Wiech, 1998]. + +Four problems with this measurement method are: + +- if the polarization state of the signal at the measurement point evolves rapidly (this is likely to be a particular problem with aerial fibre) or the signal becomes de-polarized, then it is very difficult to obtain a good extinction of the signal; +- if there is crosstalk between the channels, the crosstalk may or may not be included in the noise measurement depending on the relative polarizations of the signal and the crosstalk; +- polarization-dependent loss (PDL) can lead to significant measurement error due to the noise with the same polarization as the signal having a different amplitude to the noise with the orthogonal polarization; +- for a polarization multiplexed signal, there is a separate signal on each of the two orthogonal polarizations, so it is not possible to extinguish the signal using a polarization beam splitter. Hence, it is not possible to use this method of OSNR measurement for these signals. + +#### III.1.4 Beat noise measurement + +In this OSNR measurement method, the tapped optical signal with ASE noise is first photodetected with a low-bandwidth receiver. The optical to electrical-converted (O/E-converted) signal is split into two branches and its DC component and AC component, respectively, are obtained with a low-pass filter (LPF) and a band-pass filter (BPF) as shown in Figure III.8. Then the signal processing unit calculates the OSNR based on the obtained DC component, the obtained AC component and calibration information that depends on the modulation format and bit rate of the optical signal. + +The basic principle of this method is as follows. The DC component of the O/E-converted signal is related to the optical signal power and ASE power, while the AC component of the O/E-converted signal, mainly comprising signal–ASE beat noise and ASE–ASE beat noise, is also related to the optical signal power and ASE power [b-Chung, 2000]. Therefore, with some calibration, the optical signal power and ASE power can be extracted from the DC component and AC component and subsequently the OSNR can be obtained. + +This OSNR monitoring method is more suitable for optical phase-modulated signals, and may not work well for intensity-modulated signals. Moreover, since the O/E converted spectrum of an optical tributary signal often includes a number of tones, special care should be taken to exclude any tones within the AC component in the signal processing. + +![Schematic configuration of the beat noise measurement method](088921fa3f5a44c8551815122517eefd_img.jpg) + +The diagram illustrates the schematic configuration of the beat noise measurement method. An optical signal from a 'Monitoring port' is first processed by a 'Tunable optical filter'. The filtered signal is then sent to a 'Photo detector'. The output of the photo detector is split into two parallel processing paths: one through a 'LPF' (Low Pass Filter) and another through a 'BPF' (Band Pass Filter). Both filtered signals are then fed into a 'Signal processing' block. This block is part of a 'Monitoring module' and is connected to a 'Calibration module' via a dashed line, indicating that calibration information is provided to the signal processing unit. The diagram is labeled 'G.697(16)\_FIII.8' at the bottom right. + +Schematic configuration of the beat noise measurement method + +**Figure III.8 – Schematic configuration of the beat noise measurement method** + +### III.2 Q-factor measurement (for up to approximately 10 Gbit/s signals) + +A *Q*-factor measurement occupies an intermediate position between the classical optical parameters (power, OSNR and wavelength) and the digital end-to-end performance parameters based on BER. + +A $Q$ -factor is measured in the time domain by analysing the statistics of the pulse shape of the optical signal. Full details can be found in [ITU-T O.201]. A $Q$ -factor is a comprehensive measure for the signal quality of an optical channel taking into account the effects of noise, filtering and linear/non-linear distortions on the pulse shape, which is not possible with simple optical parameters alone. + +Under ideal conditions (only additive Gaussian noise, no linear or non-linear distortions, etc.), the BER of a binary optical channel should be the same as that indicated by a $Q$ -factor measurement. However, these idealized conditions are rarely present in real systems and the correlation between the $Q$ -factor of an optical signal and the BER measured after regeneration is influenced by the different receiver characteristics (noise bandwidth, impulse response, etc.) in the regenerator compared to that of the $Q$ -factor meter. + +NOTE – The above description of $Q$ -factor measurement is for up to 10 Gbit/s NRZ or RZ signals. $Q$ -factor measurement may not apply to 40 Gbit/s or 100 Gbit/s signals with advanced modulation formats and this is for further study. + +An additional factor that has a serious effect on the validity of a $Q$ -factor measurement at any point in an optical path is the residual dispersion present at that point. Figure III.9 is a block diagram for a simple five-span transmission system incorporating dispersion compensation modules (DCMs) in the line amplifiers. In such a system, while the end points labelled E and F usually have nominally zero residual dispersion, $Q$ -factor measurements at intermediate points of the optical path are only possible with proper dispersion compensation at those points. + +![Figure III.9: Block diagram of a five-span transmission system with dispersion compensation modules (DCMs) in the line amplifiers. The diagram shows a sequence of five spans. Each span consists of an optical fiber (represented by a circle with two loops) followed by a line amplifier (represented by a triangle). The first four spans are shown in series. The fifth span is represented by a large rectangle containing five parallel lines, representing multiple channels. Point E is at the input of the first span. Point C is between the third and fourth spans. Point D is between the fourth and fifth spans. Point F is at the output of the fifth span. Two small green boxes with arrows are shown below the fifth span, labeled G.697(16)_FIII.9.](eb5677b570ab2a3e9d8f5d35ca5b8a4d_img.jpg) + +The diagram illustrates a five-span optical transmission system. It begins with a multi-channel input at point E, which enters a series of four individual spans. Each of these spans consists of an optical fiber (indicated by a circle with two loops) and a line amplifier (indicated by a triangle). The third and fourth spans are marked with points C and D respectively. The system then enters a fifth span, which is depicted as a large rectangle containing five parallel lines, representing multiple channels. The output of this fifth span is at point F. Below the fifth span, there are two small green boxes with arrows, labeled G.697(16)\_FIII.9. + +Figure III.9: Block diagram of a five-span transmission system with dispersion compensation modules (DCMs) in the line amplifiers. The diagram shows a sequence of five spans. Each span consists of an optical fiber (represented by a circle with two loops) followed by a line amplifier (represented by a triangle). The first four spans are shown in series. The fifth span is represented by a large rectangle containing five parallel lines, representing multiple channels. Point E is at the input of the first span. Point C is between the third and fourth spans. Point D is between the fourth and fifth spans. Point F is at the output of the fifth span. Two small green boxes with arrows are shown below the fifth span, labeled G.697(16)\_FIII.9. + +**Figure III.9 – Five-span transmission system incorporating dispersion compensation modules in the line amplifiers** + +Figure III.10 shows the residual dispersion versus distance for a system where the dispersion of each nominally 80 km span is compensated by an 80 km DCM embedded in each line amplifier, and an additional DCM within the receiving preamplifier. In this case, for example, the *Q*-factor measured at point C (the input to the third line amplifier) is quite different to the *Q*-factor at point D (the output of the same amplifier) due to the large difference in residual dispersion of the two points. + +![Figure III.10: Residual dispersion versus distance for a simple system. The graph shows a sawtooth pattern of residual dispersion (ps/nm) over distance (km). The y-axis ranges from -200 to 1600 ps/nm, and the x-axis ranges from 0 to 450 km. The dispersion increases linearly from 0 ps/nm at 0 km to approximately 1400 ps/nm at 80 km, then drops sharply to approximately -100 ps/nm at 80 km. This pattern repeats for subsequent spans. Point C is marked at the peak of the third sawtooth (approx. 240 km, 1400 ps/nm), and point D is marked at the trough of the third sawtooth (approx. 240 km, -100 ps/nm). The label G.697(16)_FIII.10 is in the bottom right corner.](920eeb131e71a5b81535239f1c838c68_img.jpg) + +Figure III.10: Residual dispersion versus distance for a simple system. The graph shows a sawtooth pattern of residual dispersion (ps/nm) over distance (km). The y-axis ranges from -200 to 1600 ps/nm, and the x-axis ranges from 0 to 450 km. The dispersion increases linearly from 0 ps/nm at 0 km to approximately 1400 ps/nm at 80 km, then drops sharply to approximately -100 ps/nm at 80 km. This pattern repeats for subsequent spans. Point C is marked at the peak of the third sawtooth (approx. 240 km, 1400 ps/nm), and point D is marked at the trough of the third sawtooth (approx. 240 km, -100 ps/nm). The label G.697(16)\_FIII.10 is in the bottom right corner. + +**Figure III.10 – Residual dispersion versus distance for a simple system** + +A solution to the dispersion map, illustrated in Figure III.10, is to only measure the *Q*-factor at the amplifier outputs (e.g., point D). + +The residual dispersion map in Figure III.10 is for a wavelength where the fibre dispersion is reasonably accurately compensated for by the DCM. In long-haul systems that cover a large wavelength range, however, the fact that the slope of the fibre dispersion with wavelength typically does not exactly match the inverse of the slope of the DCM dispersion with wavelength means that the residual dispersion map is different over the range of channel wavelengths. This is illustrated in Figure III.11 where the residual dispersion maps of the extreme wavelength channels are also shown. + +![Figure III.11: Residual dispersion versus distance for a simple system with a wide wavelength range. The graph shows five linearly increasing dispersion curves starting from 0 ps/nm at 0 km. The curves are labeled C (top) and D (bottom). At each amplifier location (approx. 80, 160, 240, 320 km), the dispersion is abruptly reset to a negative value. The x-axis is Distance (km) from 0 to 450, and the y-axis is Residual dispersion (ps/nm) from -1000 to 2500. A label G.697(16)_FIII.11 is in the bottom right.](a2dcc4a0703102026ec86e82caa4985e_img.jpg) + +Figure III.11: Residual dispersion versus distance for a simple system with a wide wavelength range. The graph shows five linearly increasing dispersion curves starting from 0 ps/nm at 0 km. The curves are labeled C (top) and D (bottom). At each amplifier location (approx. 80, 160, 240, 320 km), the dispersion is abruptly reset to a negative value. The x-axis is Distance (km) from 0 to 450, and the y-axis is Residual dispersion (ps/nm) from -1000 to 2500. A label G.697(16)\_FIII.11 is in the bottom right. + +**Figure III.11 – Residual dispersion versus distance for a simple system with a wide wavelength range** + +In the case of a more complex dispersion map, as illustrated in Figure III.12, where there are DCMs in the transmitter and the receiver as well as embedded in the line amplifiers, the points with zero dispersion do not now necessarily coincide with the output of line amplifiers. Here, additional compensation devices in the measuring equipment would be required for *Q*-factor measurement to be valid at these monitoring points. + +![Figure III.12: Residual dispersion versus distance for a more complex system. The graph shows a single dispersion curve starting at -1000 ps/nm at 0 km (labeled E). The curve increases linearly and is reset at amplifier locations (approx. 80, 160, 240, 320 km). The final point at 400 km is labeled F. The x-axis is Distance (km) from 0 to 450, and the y-axis is Residual dispersion (ps/nm) from -1500 to 1500. A label G.697(16)_FIII.12 is in the bottom right.](20e597e389dfd8d131e05ad6e1617dcd_img.jpg) + +Figure III.12: Residual dispersion versus distance for a more complex system. The graph shows a single dispersion curve starting at -1000 ps/nm at 0 km (labeled E). The curve increases linearly and is reset at amplifier locations (approx. 80, 160, 240, 320 km). The final point at 400 km is labeled F. The x-axis is Distance (km) from 0 to 450, and the y-axis is Residual dispersion (ps/nm) from -1500 to 1500. A label G.697(16)\_FIII.12 is in the bottom right. + +**Figure III.12 – Residual dispersion versus distance for a more complex system** + +## Appendix IV + +## Possible positions for suitable monitoring equipment and their relative functions in several optical network elements + +(This appendix does not form an integral part of this Recommendation.) + +### IV.1 Introduction + +While OM is implemented (and in service) in many current optical transmission systems, there are significant differences between the OM deployments between them. This is due to the presence of different transmission and control system designs, the size of the network and different strategies for impairment management in the various systems. For this reason, a general requirement as to which parameter value with which particular accuracy is a reliable indicator of the operational condition of such a system cannot be generalized. + +The choice of which option to deploy depends upon the specific characteristics of the ONE, in particular for a DWDM system, whose characteristics include length, number of spans, number of channels and inaccessibility of the sites, as well as cost/benefit considerations. Particular consideration is required because, as the number of monitoring points grows, there is an increasing consumption of signal power with a consequent reduction of the DWDM system reach. + +As a conclusion, it is underlined that the possible positions for suitable monitoring points and their relative functions in several ONEs which are shown in this appendix should be considered as examples and not as requirements. These examples are of interest because they can show what is feasible from the technological point of view and what network operators could need. + +A general model for possible monitoring positions in an ONE is shown in Figure IV.1. + +![Diagram of an optical network element showing possible monitoring positions.](dc1f232cfd39be5c20b21374ad4c04c0_img.jpg) + +The diagram illustrates a general model for an optical network element (ONE) enclosed in a dashed box. At the top, a box labeled 'Optical functions (receiving, transmitting)' is connected to the external network. Below this, three stacked boxes represent internal optical functions: 'Optical switching functions', 'Optical DEMUX/MUX functions', and 'Optical amplification functions'. Arrows indicate the flow of optical signals between these functions. Red dots, labeled 'Possible monitoring position' in the legend, are placed at various points: at the input/output of the top box, between the top box and the switching functions, between the switching and DEMUX/MUX functions, between the DEMUX/MUX and amplification functions, and at the output of the amplification functions. The diagram is labeled 'G.697(12)\_FIV.1' at the bottom right. + +Diagram of an optical network element showing possible monitoring positions. + +Figure IV.1 – Example of embedded monitoring equipment positioning inside an optical network element + +### IV.2 Embedded monitoring points + +#### IV.2.1 Dense wavelength division multiplexing line segment + +An example of positioning of EME in a long-distance DWDM line segment with optical channels operating at 10 Gbit/s, 40 Gbit/s or 100 Gbit/s is shown in Figure IV.2. + +![Figure IV.2: Example of embedded monitoring equipment positioning inside a long-distance dense wavelength division multiplexing line segment. The diagram shows a DWDM line segment with two stages of optical amplification. Each stage consists of an optical multiplexer (OM), a booster amplifier (B), a dispersion compensating module (DCM), a preamplifier (P), and an optical demultiplexer (OD). The first stage is labeled 'Two-stage line amplifier' and contains components 3, 4, 5, 6, 7, 8. The second stage contains components 9, 10. The line segment starts at point 1 with single channel interfaces (Rx, Tx λ1, Rx, Tx λN) and ends at point 12 with single channel interfaces (Rx λ1, Tx, Rx λN, Tx). Possible EME positions are indicated by red dots at points 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12. A legend at the bottom defines the symbols: B = Booster amplifier, P = Preamplifier, Tx = Transmitter, Rx = Receiver, DCM = Dispersion compensating module, and a red dot = Possible EME position. The diagram is labeled G.697(12)_FIV.2.](e05b36c0d46549e681ce6581422c66b2_img.jpg) + +Figure IV.2: Example of embedded monitoring equipment positioning inside a long-distance dense wavelength division multiplexing line segment. The diagram shows a DWDM line segment with two stages of optical amplification. Each stage consists of an optical multiplexer (OM), a booster amplifier (B), a dispersion compensating module (DCM), a preamplifier (P), and an optical demultiplexer (OD). The first stage is labeled 'Two-stage line amplifier' and contains components 3, 4, 5, 6, 7, 8. The second stage contains components 9, 10. The line segment starts at point 1 with single channel interfaces (Rx, Tx λ1, Rx, Tx λN) and ends at point 12 with single channel interfaces (Rx λ1, Tx, Rx λN, Tx). Possible EME positions are indicated by red dots at points 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12. A legend at the bottom defines the symbols: B = Booster amplifier, P = Preamplifier, Tx = Transmitter, Rx = Receiver, DCM = Dispersion compensating module, and a red dot = Possible EME position. The diagram is labeled G.697(12)\_FIV.2. + +**Figure IV.2 – Example of embedded monitoring equipment positioning inside a long-distance dense wavelength division multiplexing line segment** + +The optical parameters listed in clause 10 can be measured in the various monitoring points of Figure IV.2 according to Table IV.1. + +**Table IV.1 – Possible monitoring in a dense wavelength division multiplexing line segment** + +| Monitoring parameters | Embedded monitoring equipment position | +|---------------------------------------------------------------------------|----------------------------------------| +| a) Total power at input of various stages of optical amplification | 3, 5, 7, 9 | +| b) Total power at output of various stages of optical amplification | 4, 6, 8, 10 | +| c) Channel input power | 1, 11 | +| d) Channel output power | 2, 12 | +| e) Channel power at the output of various stages of optical amplification | 4, 6, 8, 10 | +| f) Channel OSNR at the output of various stages of optical amplification | 4, 6, 8, 10 | +| g) Channel wavelength | 2 | + +NOTE – This table lists possible monitoring positions. The appropriate choice of monitoring depends on the particular system (see clause IV.1). + +#### IV.2.2 Reconfigurable optical add-drop multiplexers + +An example of positioning of embedded monitoring equipment in a ROADM is shown in Figure IV.3. + +![Figure IV.3: Example of embedded monitoring equipment positioning inside a reconfigurable optical add-drop multiplexer. The diagram shows a ROADM connected to two DWDM line segments via Optical Line Amplifiers (OLA). The ROADM contains an internal structure with an Input port, a Pre-amplifier (PA), a Demux or WSS, a Wavelength Selective Switch (WSS), a Booster-amplifier (BA), and an Output port. Drop and Add ports are also shown. Red dots indicate possible EME positions at various points within the ROADM components.](318886a86a1dcc59e1fc83db6f157c60_img.jpg) + +The diagram illustrates the internal architecture of a ROADM. It consists of an Input port (3) leading to a Pre-amplifier (PA), which then connects to a Demux or WSS. The Demux or WSS has multiple output paths, one of which leads to Drop port(s) (2). Another path from the Demux or WSS connects to a Wavelength Selective Switch (WSS). The WSS has multiple output paths, one of which leads to a Booster-amplifier (BA), which then connects to the Output port (6). Other output paths from the WSS lead to Add port(s) (1). Red dots indicate possible EME positions at various points: at the input (3), after the PA (4), at the Demux or WSS (7), at the WSS (5), and at the BA (6). The ROADM is connected to two DWDM line segments via OLAs and Fibres. The legend identifies the symbols for PA, BA, Possible EME position, Wavelength multiplexer or demultiplexer, and WSS. + +Figure IV.3: Example of embedded monitoring equipment positioning inside a reconfigurable optical add-drop multiplexer. The diagram shows a ROADM connected to two DWDM line segments via Optical Line Amplifiers (OLA). The ROADM contains an internal structure with an Input port, a Pre-amplifier (PA), a Demux or WSS, a Wavelength Selective Switch (WSS), a Booster-amplifier (BA), and an Output port. Drop and Add ports are also shown. Red dots indicate possible EME positions at various points within the ROADM components. + +**Figure IV.3 – Example of embedded monitoring equipment positioning inside a reconfigurable optical add-drop multiplexer** + +The optical parameters listed in clause 10 can be measured in the various EMEs of Figure IV.3 according to Table IV.2. + +**Table IV.2 – Possible monitoring in an example reconfigurable optical add-drop multiplexer** + +| Monitoring parameters | Embedded monitoring equipment position | +|---------------------------------------------------------------------------|----------------------------------------| +| a) Total power at input of various stages of optical amplification | 3, 5 | +| b) Total power at output of various stages of optical amplification | 4, 6 | +| c) Channel input power | 1 | +| d) Channel output power | 2 | +| e) Channel power at the output of various stages of optical amplification | 4, 6 | +| f) Channel OSNR at the output of various stages of optical amplification | 4, 6 | +| g) Channel wavelength | 1 | +| h) Total power | 7 | + +NOTE – This table lists possible monitoring positions. The appropriate choice of monitoring depends on the particular system (see clause IV.1). + +The position and the function of the EMEs inside the WSS are for further study. + +### IV.3 External monitoring points + +#### IV.3.1 Dense wavelength division multiplexing line segment + +An example of positioning of EMPs in a long-distance DWDM line segment with optical channels operating at 10 Gbit/s, 40 Gbit/s or 100 Gbit/s is shown in Figure IV.4. + +![Diagram of a long-distance DWDM line segment showing external monitoring point (EMP) positioning. The diagram illustrates two parallel optical paths. Each path starts with 'Single channel interfaces' (Rx/Tx blocks for λ1 and λN) connected to an Optical Multiplexer (OM). The OM output connects to a Booster amplifier (B), which has an EMP position marked. This is followed by a 'Two-stage line amplifier' block containing a Dispersion Compensating Module (DCM) and two more EMP positions. The line amplifier output connects to a Preamplifier (P), which also has an EMP position. Finally, the Preamplifier output connects to an Optical Demultiplexer (OD), which then connects back to the 'Single channel interfaces' (Tx/Rx blocks for λ1 and λN). A legend at the bottom defines the components: B = Booster amplifier, P = Preamplifier, ● = Possible EMP position, Tx = Transmitter, Rx = Receiver, and DCM = Dispersion compensating module. The diagram is labeled G.697(12)_FIV.4.](05eb72d372e4bf78e3d6a64949d77bcc_img.jpg) + +Two-stage line amplifier + +G.697(12)\_FIV.4 + +B = Booster amplifier +P = Preamplifier +● = Possible EMP position +Tx = Transmitter +Rx = Receiver +DCM = Dispersion compensating module + +Diagram of a long-distance DWDM line segment showing external monitoring point (EMP) positioning. The diagram illustrates two parallel optical paths. Each path starts with 'Single channel interfaces' (Rx/Tx blocks for λ1 and λN) connected to an Optical Multiplexer (OM). The OM output connects to a Booster amplifier (B), which has an EMP position marked. This is followed by a 'Two-stage line amplifier' block containing a Dispersion Compensating Module (DCM) and two more EMP positions. The line amplifier output connects to a Preamplifier (P), which also has an EMP position. Finally, the Preamplifier output connects to an Optical Demultiplexer (OD), which then connects back to the 'Single channel interfaces' (Tx/Rx blocks for λ1 and λN). A legend at the bottom defines the components: B = Booster amplifier, P = Preamplifier, ● = Possible EMP position, Tx = Transmitter, Rx = Receiver, and DCM = Dispersion compensating module. The diagram is labeled G.697(12)\_FIV.4. + +**Figure IV.4 – Example of external monitoring point positioning inside a long-distance dense wavelength division multiplexing line segment** + +All of the optical parameters listed in clause 8 can be measured in the various monitoring points of Figure IV.4 with suitable external measurement equipment. The appropriate choice of which monitoring points are provided depends on the particular system (see clause IV.1). + +#### IV.3.2 Reconfigurable optical add-drop multiplexers + +An example of positioning of EMPs in a ROADM is shown in Figure IV.5. + +![Diagram of a ROADM internal structure showing monitoring points. The top part shows a ROADM connected to two DWDM line segments via fibre and OLA (Optical Line Amplifier) units. The bottom part is a detailed view of the ROADM internal components: Input port (1), PA (Pre-amplifier), Demux or WSS, Drop port(s), WSS, BA (Booster-amplifier), Output port (4), and Add port(s). Red dots indicate possible EMP (External Monitoring Point) positions at various locations within the internal components. A legend defines the symbols: green triangle for PA, red triangle for BA, red dot for Possible EMP position, trapezoid for Wavelength multiplexer or demultiplexer, and WSS for Wavelength selective switch. The diagram is labeled G.697(12)_FIV.5.](f9c64800d9bace9b4315646d1057be3c_img.jpg) + +Diagram of a ROADM internal structure showing monitoring points. The top part shows a ROADM connected to two DWDM line segments via fibre and OLA (Optical Line Amplifier) units. The bottom part is a detailed view of the ROADM internal components: Input port (1), PA (Pre-amplifier), Demux or WSS, Drop port(s), WSS, BA (Booster-amplifier), Output port (4), and Add port(s). Red dots indicate possible EMP (External Monitoring Point) positions at various locations within the internal components. A legend defines the symbols: green triangle for PA, red triangle for BA, red dot for Possible EMP position, trapezoid for Wavelength multiplexer or demultiplexer, and WSS for Wavelength selective switch. The diagram is labeled G.697(12)\_FIV.5. + +**Figure IV.5 – Example of external monitoring point positioning inside an example reconfigurable optical add-drop multiplexer** + +All of the optical parameters listed in clause 10 can be measured in the various monitoring points of Figure IV.5 with suitable external measurement equipment. The appropriate choice of which monitoring points are provided depends on the particular system (see clause IV.1). + +# Appendix V + +## Parameter encoding + +(This appendix does not form an integral part of this Recommendation.) + +This appendix contains a possible encoding scheme for the communication of information relating to optical parameters. The use of this information, how it is communicated, whether information for any particular parameter is included and whether the value for any parameter is obtained by measurement, measurement prior to system installation or purely provisioned, is outside the scope of this appendix. + +## V.1 Wavelength ID (32 bits) + +This field contains the wavelength label and is composed of four sub-fields: + +- **Grid** (3 bits, 0 to 2): The value for grid is set to 1 for the ITU-T DWDM grid as defined in [b-ITU-T G.694.1], set to 2 for the ITU-T coarse wavelength division multiplexing (CWDM) grid as defined in [b-ITU-T G.694.2]. The values of 0 and 3 to 7 are reserved for future use. +- **Channel spacing** (4 bits, 3 to 6): The channel spacing encoding when Grid is set to "1" (DWDM) is shown in Table V.1 and the channel spacing encoding when Grid is set to "2" (CWDM) is shown in Table V.2 + +**Table V.1 – Dense wavelength division multiplexing channel spacing encoding** + +| Channel spacing (GHz) | Value | +|-------------------------|------------| +| 100 | 1 | +| 50 | 2 | +| 25 | 3 | +| 12.5 | 4 | +| Flexible grid | 5 | +| Reserved for future use | 0, 6 to 15 | + +For channel spacings greater than 100 GHz, there is more than one possible choice of grid (see [b-ITU-T G.694.1]), so the appropriate element of the 100 GHz spaced grid should be encoded. + +**Table V.2 – Coarse wavelength division multiplexing channel spacing encoding** + +| Channel spacing (nm) | Value | +|-------------------------|------------| +| 20 | 1 | +| Reserved for future use | 0, 2 to 15 | + +- $n$ (16 bits, 7 to 22): The value used to compute the frequency as shown below: When the grid is "1", frequency (THz) = $193.1 \text{ THz} + n \times \text{channel spacing (THz)}$ For the case where the channel spacing value is set to "5", a channel spacing of 6.25 GHz should be used in the above formula. When the grid is "2", wavelength (nm) = $1\,471 \text{ nm} + n \times \text{channel spacing (nm)}$ $n$ is encoded as a 16-bit two's complement number. +- $m$ (9 bits, 23 to 31): When the grid is "1" and the channel spacing value is set to "5" this is the value used to compute the slot width as: $\text{slot width (GHz)} = 12.5 \text{ GHz} \times m$ (see [b-ITU-T G.694.1]) otherwise set to 0; $m$ is encoded as a 9-bit unsigned integer. + +As an example, the encoding of the 193.85 THz element (approximately 1 546.518 nm) from the 50 GHz spaced grid in [b-ITU-T G.694.1] would be grid = 1, channel spacing = 2, $n = 15$ , Reserved = 0. This results in an encoding of 000000000 0000000000001111 0010 001 or 0x00000791. + +### V.2 Parameter ID source (8 bits) + +This field defines the source of the parameter ID lookup table. The value "1" corresponds to this Recommendation, all other values are reserved for future use. + +### V.3 Parameter ID (8 bits) + +When the parameter ID source is equal to "1", the parameter encoding shown in Table V.3 applies. For all other values of the parameter ID source, the parameter encoding is given in the document referred to in V.2. + +**Table V.3 – Parameter ID encoding** + +| Value | Parameter | Unit | Notes | +|-------|------------------------------------|-------------|-------------------------------------------------------------------------------------------------------| +| 1 | Total power | dBm | | +| 2 | Channel power | dBm | | +| 3 | Frequency deviation from nominal | GHz | For DWDM channels | +| 4 | Wavelength deviation from nominal | nm | For CWDM channels | +| 5 | OSNR | dB (0.1 nm) | Referred to a 0.1 nm noise bandwidth | +| 6 | Q | – | Linear $Q$ | +| 7 | Polarization mode dispersion (PMD) | ps | Mean differential group delay (DGD). This parameter is normally only measured at time of installation | +| 8 | Residual dispersion | ps/nm | This parameter is normally only measured at time of installation | + +All other values of the parameter ID are reserved for future use. + +### V.4 Value of parameters (32 bits) + +The parameter value is encoded as a 32-bit floating-point number according to [b-IEEE 754]. The 32-bit number is divided into a sign (1 bit), an exponent (8 bits) and a mantissa (23 bits). The parameter value is then: + +$$\text{Value} = (-1)^{\text{sign}} \times 2^{(\text{exponent} - 127)} \times (\text{number between 1.0 and 2.0 derived from mantissa})$$ + +For details see [b-IEEE 754]. + +# Bibliography + +- [b-ITU-T G.694.1] Recommendation ITU-T G.694.1 (2012), *Spectral grids for WDM applications: DWDM frequency grid*. +- [b-ITU-T G.694.2] Recommendation ITU-T G.694.2 (2003), *Spectral grids for WDM applications: CWDM wavelength grid*. +- [b-ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016), *Interfaces for the optical transport network*. +- [b-ITU-T G.826] Recommendation ITU-T G.826 (2002), *End-to-end error performance parameters and objectives for international, constant bit-rate digital paths and connections*. +- [b-ITU-T G-Sup.39] ITU-T G-series Recommendations – Supplement 39 (2016), *Optical system design and engineering considerations*. +- [b-IEC 61280-2-9] IEC 61280-2-9:2009, *Fibre optic communication subsystem test procedures – Part 2-9: Digital systems – Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems*. +- [b-IEEE 754] IEEE Std 754-2008, *IEEE Standard for Floating-Point Arithmetic*. +- [b-Chung, 2000] Chung, Y.C., Shin, S.K., Park, K.J. (2000), *A novel optical signal-to-noise ratio monitoring technique for WDM networks. In: Proceedings of the Optical Fiber Communication Conference (OFC2000)*, Baltimore, March 2000, vol. 2, pp. 182-184, paper WK6. Technical Digest Series. Washington, DC: Optical Society of America. +- [b-Rasztovits-Wiech, 1998] Rasztovits-Wiech, M., Danner, M., Leeb, W.R. (1998), *Optical signal-to-noise measurement in WDM networks using polarization extinction. In: Proceedings of the 34th European Conference on Optical Communication (ECOC 1998)*, Madrid, September 1998, pp. 549-550. + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.7041-201608-I_PDF-E/raw.md b/marked/G/T-REC-G.7041-201608-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..3b0b5564c6ee942c0cf994c0b6ae4671133baccf --- /dev/null +++ b/marked/G/T-REC-G.7041-201608-I_PDF-E/raw.md @@ -0,0 +1,2756 @@ + + +**ITU-T** + +**G.7041/Y.1303** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(08/2016) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Data over Transport – Generic aspects – General + +SERIES Y: GLOBAL INFORMATION +INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, +NEXT-GENERATION NETWORKS, INTERNET OF +THINGS AND SMART CITIES + +Internet protocol aspects – Transport + +# --- **Generic framing procedure** + +Recommendation ITU-T G.7041/Y.1303 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| General | G.7000–G.7099 | +| Transport network control aspects | G.7700–G.7799 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.7041/Y.1303 + +# Generic framing procedure + +# Summary + +Recommendation ITU-T G.7041/Y.1303 defines a generic framing procedure (GFP) to delineate octet-aligned, variable-length payloads from higher-level client signals for subsequent mapping into octet-synchronous paths, such as those defined in Recommendations ITU-T G.707/Y.1322, ITU-T G.8040/Y.1340 and ITU-T G.709/Y.1331. This Recommendation defines: + +- frame formats for protocol data units (PDUs) transferred between GFP initiation and termination points; +- the mapping procedure for the client signals into GFP; +- responses to certain defect conditions. + +This edition adds the information from Amendment 1 (2012), Amendment 2 (2012) and Amendment 3 (2015) to Recommendation ITU-T G.7041 (2011), in addition to new material and text enhancements from contributions to the February 2016 meeting. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.7041/Y.1303 | 2001-12-14 | 15 | 11.1002/1000/5644 | +| 1.1 | ITU-T G.7041/Y.1303 (2001) Amd. 1 | 2002-06-13 | 15 | 11.1002/1000/6062 | +| 1.2 | ITU-T G.7041/Y.1303 (2001) Cor. 1 | 2003-03-16 | 15 | 11.1002/1000/6285 | +| 1.3 | ITU-T G.7041/Y.1303 (2001) Amd. 2 | 2003-03-16 | 15 | 11.1002/1000/6284 | +| 2.0 | ITU-T G.7041/Y.1303 | 2003-12-14 | 15 | 11.1002/1000/7082 | +| 2.1 | ITU-T G.7041/Y.1303 (2003) Amd. 1 | 2004-10-07 | 15 | 11.1002/1000/7352 | +| 2.2 | ITU-T G.7041/Y.1303 (2003) Amd. 2 | 2004-06-13 | 15 | 11.1002/1000/7353 | +| 2.3 | ITU-T G.7041/Y.1303 (2003) Cor. 1 | 2005-01-13 | 15 | 11.1002/1000/7476 | +| 2.4 | ITU-T G.7041/Y.1303 (2003) Amd. 3 | 2005-01-13 | 15 | 11.1002/1000/7475 | +| 3.0 | ITU-T G.7041/Y.1303 | 2005-08-22 | 15 | 11.1002/1000/8528 | +| 3.1 | ITU-T G.7041/Y.1303 (2005) Amd. 1 | 2006-03-29 | 15 | 11.1002/1000/8769 | +| 3.2 | ITU-T G.7041/Y.1303 (2005) Cor. 1 | 2006-12-14 | 15 | 11.1002/1000/8997 | +| 3.3 | ITU-T G.7041/Y.1303 (2005) Amd. 2 | 2007-07-29 | 15 | 11.1002/1000/9170 | +| 4.0 | ITU-T G.7041/Y.1303 | 2008-10-07 | 15 | 11.1002/1000/9399 | +| 4.1 | ITU-T G.7041/Y.1303 (2008) Amd. 1 | 2009-01-13 | 15 | 11.1002/1000/9655 | +| 4.2 | ITU-T G.7041/Y.1303 (2008) Amd. 2 | 2010-07-29 | 15 | 11.1002/1000/10893 | +| 5.0 | ITU-T G.7041/Y.1303 | 2011-04-13 | 15 | 11.1002/1000/11133 | +| 5.1 | ITU-T G.7041/Y.1303 (2011) Amd. 1 | 2012-02-13 | 15 | 11.1002/1000/11506 | +| 5.2 | ITU-T G.7041/Y.1303 (2011) Amd. 2 | 2012-10-29 | 15 | 11.1002/1000/11799 | +| 5.3 | ITU-T G.7041/Y.1303 (2011) Amd. 3 | 2015-01-13 | 15 | 11.1002/1000/12378 | +| 6.0 | ITU-T G.7041/Y.1303 | 2016-08-06 | 15 | 11.1002/1000/12801 | + +## Keywords + +Generic framing procedure, optical transport network, synchronous digital hierarchy + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2017 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +| | | Page | +|-------|---------------------------------------------------------------------------------------------------------|------| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Terms and definitions ..... | 3 | +| 4 | Abbreviations and acronyms ..... | 4 | +| 5 | Conventions ..... | 6 | +| 6 | Aspects common to both frame-mapped and transparent-mapped modes of GFP ..... | 6 | +| 6.1 | Basic signal structure for GFP client frames ..... | 7 | +| 6.2 | GFP control frames..... | 18 | +| 6.3 | GFP frame-level functions ..... | 19 | +| 6.4 | Management communications frame ..... | 24 | +| 7 | Payload-specific aspects for frame-mapped GFP ..... | 24 | +| 7.1 | Ethernet media access control payload..... | 24 | +| 7.2 | HDLC/PPP payload..... | 27 | +| 7.3 | Fibre channel payload via FC-BBW_SONET ..... | 28 | +| 7.4 | Error handling in frame-mapped GFP ..... | 29 | +| 7.5 | IEEE 802.17 resilient packet ring payload ..... | 29 | +| 7.6 | Direct mapping of multiprotocol label switching into GFP-F frames..... | 30 | +| 7.7 | Direct mapping of IP and OSI network layer PDUs into GFP-F frames ..... | 31 | +| 7.8 | DVB ASI payload..... | 32 | +| 7.9 | Transporting Ethernet 10GBASE-R payloads with preamble transparency
and ordered set information..... | 33 | +| 7.10 | Precision time protocol..... | 36 | +| 7.11 | Synchronization status messages..... | 37 | +| 8 | Payload-specific aspects for transparent mapping of 8B/10B clients into GFP ..... | 38 | +| 8.1 | Common aspects of GFP-T ..... | 38 | +| 8.2 | Running disparity in 64B/65B codes..... | 42 | +| 8.3 | Client-specific signal fail aspects ..... | 44 | +| 8.4 | Synchronous full-rate transparent mapping of 8B/10B clients into GFP ..... | 47 | +| 8.5 | Asynchronous (full- or sub-rate) mapping of 8B/10B clients into GFP ..... | 50 | +| | Appendix I – Examples of functional models for GFP applications ..... | 51 | +| | Appendix II – Sample GFP payload types..... | 53 | +| | Appendix III – GFP frame example illustrating transmission order and CRC calculation ..... | 54 | +| III.1 | Worked example for a GFP-F frame ..... | 54 | +| III.2 | Worked example for a GFP-T superblock CRC calculation ..... | 57 | +| III.3 | Worked example for a GFP-F encapsulated MPLS frame ..... | 57 | + +| | Page | +|------------------------------------------------------------------------------------|-------------| +| Appendix IV – Number of superblocks used in transparent GFP..... | 59 | +| IV.1    Introduction ..... | 59 | +| IV.2    Calculation of spare bandwidth ..... | 59 | +| IV.3    Calculation of available bandwidth for CMFs and MCFs..... | 60 | +| Appendix V – Bandwidth requirements for Ethernet transport ..... | 62 | +| Appendix VI – Ethernet physical layer defect signals ..... | 65 | +| Appendix VII – Ethernet throughput of ODUflex for GFP-F mapped client signals..... | 67 | +| Bibliography..... | 69 | + +# Introduction + +A generic framing procedure (GFP) provides a generic mechanism to adapt traffic from higher-layer client signals over a transport network. Client signals may be protocol data unit- (PDU)-oriented [such as Internet protocol/point-to-point protocol (IP/PPP) or Ethernet media access control (MAC)] or block-code oriented constant bit rate stream [such as fibre channel or enterprise systems connection/single-byte command code sets connection (ESCON/SBCON)]. + +The GFP specification consists of both common and client-specific aspects. Common aspects of GFP apply to all GFP-adapted traffic and they are specified in clause 6. Client-specific aspects of GFP are specified in clauses 7 and 8. Currently, two modes of client signal adaptation are defined for GFP. + +- A PDU-oriented adaptation mode, referred to as frame-mapped GFP (GFP-F), is specified in clause 7. +- A block-code oriented adaptation mode, referred to as transparent GFP (GFP-T), is specified in clause 8. + +Figure 1 illustrates the relationship between the higher-layer client signals, GFP and GFP transport paths. + +![](d793cf7c174b89eb024d132f00679787_img.jpg) + +| | | | +|------------------------------------------------------|-------------------------------|----------------------| +| Ethernet | IP/PPP | Other client signals | +| GFP – Client-specific aspects
(payload dependent) | | | +| GFP – Common aspects
(payload independent) | | | +| SDH VC- n path | Other octet-synchronous paths | OTN ODUk path | + +G.7041-Y.1303(11)\_F01 + +**Figure 1 – GFP relationship to client signals and transport paths** + +Figure 2 illustrates the environment in which GFP operates. + +![Figure 2: GFP functional model (single client). The diagram shows a central 'Transport layer network' connected to two 'Bridge or switch or router function in TNE' blocks. The left TNE is connected to a 'Data layer network' and a 'PHY-X' block (which connects to interfaces A and B). The right TNE is connected to a 'PHY-X' block (which connects to interfaces B' and A'). Both TNEs have 'GFP-T' and 'GFP-F' blocks connected to the transport network. The 'Data layer network' has interfaces C and C' connected to 'GFP-F' blocks. The 'PHY-X' blocks are connected to various physical interfaces: 10BASE, 100BASE, 1000BASE, 10GBASE, ESCON, FICON, Fibre channel, and 1000BASE.](9791722d75115ddcc599b07d7bc35d73_img.jpg) + +G.7041-Y.1303(11)\_F02 + +Figure 2: GFP functional model (single client). The diagram shows a central 'Transport layer network' connected to two 'Bridge or switch or router function in TNE' blocks. The left TNE is connected to a 'Data layer network' and a 'PHY-X' block (which connects to interfaces A and B). The right TNE is connected to a 'PHY-X' block (which connects to interfaces B' and A'). Both TNEs have 'GFP-T' and 'GFP-F' blocks connected to the transport network. The 'Data layer network' has interfaces C and C' connected to 'GFP-F' blocks. The 'PHY-X' blocks are connected to various physical interfaces: 10BASE, 100BASE, 1000BASE, 10GBASE, ESCON, FICON, Fibre channel, and 1000BASE. + +**Figure 2 – GFP functional model (single client)** + +In the frame-mapped adaptation mode, the client/GFP adaptation function may operate at the data link layer (or higher layer) of the client signal. Client PDU visibility is required. This visibility is obtained when the client PDUs are received from either the data layer network [e.g., Internet protocol (IP) router fabric or Ethernet switch fabric (C/C' in Figure 2)] or, e.g., a bridge, switch or router function in a transport network element (TNE). In the latter case, the client PDUs are received via, e.g., an Ethernet interface (A/A' in Figure 2). + +For the transparent adaptation mode, the client/GFP adaptation function operates on the coded character stream rather than on the incoming client PDUs. Thus, processing of the incoming codeword space for the client signal is required (B/B' in Figure 2). + +Typically, interconnections can be set up between ports A and A', B and B', C and C', A and C', and C and A'. Note that the physical port type of B and B' must be the same to support an interconnection, while the physical port type of A and A' may be different. + +Some high-level functional models associated with the above GFP processing can be found in Appendix I. + +# Generic framing procedure + +# 1 Scope + +This Recommendation defines a generic framing procedure (GFP) to encapsulate variable-length payload of various client signals for subsequent transport over synchronous digital hierarchy (SDH), plesiochronous digital hierarchy (PDH) and optical transport network (OTN) networks as defined in [ITU-T G.707], [ITU-T G.8040] and [ITU-T G.709]. This Recommendation defines the: + +- frame formats for protocol data units (PDUs) transferred between GFP initiation and termination points; +- mapping procedure for the client signals into GFP. + +The framing procedure described in this Recommendation can be applied to both the encapsulation of entire client frames (frame-mapped GFP), in which a single client frame is mapped into a single GFP frame, and to character-mapped transport (transparent GFP), in which a number of client data characters are mapped into efficient block codes for transport within a GFP frame. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.707] Recommendation ITU-T G.707/Y.1322 (2007), *Network node interface for the synchronous digital hierarchy (SDH)*. +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016), *Interfaces for the optical transport network (OTN)*. +- [ITU-T G.781] Recommendation ITU-T G.781 (2008), *Synchronization layer functions*. +- [ITU-T G.783] Recommendation ITU-T G.783 (2006), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks*. +- [ITU-T G.798] Recommendation ITU-T G.798 (2012), *Characteristics of optical transport network hierarchy equipment functional blocks*. +- [ITU-T G.806] Recommendation ITU-T G.806 (2012), *Characteristics of transport equipment – Description methodology and generic functionality*. +- [ITU-T G.8021] Recommendation ITU-T G.8021/Y.1341 (2016), *Characteristics of Ethernet transport network equipment functional blocks*. +- [ITU-T G.8040] Recommendation ITU-T G.8040/Y.1340 (2005), *GFP frame mapping into plesiochronous digital hierarchy (PDH)*. +- [ITU-T G.8264] Recommendation ITU-T G.8264/Y.1364 (2013), *Distribution of timing information through packet networks*. +- [ITU-T G.8275.1] Recommendation ITU-T G.8275.1/Y.1369.1 (2016), *Precision time protocol telecom profile for phase/time synchronization with full timing support from the network*. + +| | | +|-------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T H.222.0] | Recommendation ITU-T H.222.0 (2014) ISO/IEC 13818-1:2015, Information technology – Generic coding of moving pictures and associated audio information: Systems. | +| [ITU-T I.363.1] | Recommendation ITU-T I.363.1 (1996), B-ISDN ATM Adaptation Layer specification: Type 1 AAL. | +| [ITU-T I.432.1] | Recommendation ITU-T I.432.1 (1999), B-ISDN user-network interface – Physical layer specification: General characteristics. | +| [ITU-T X.233] | Recommendation ITU-T X.233 (1997) ISO/IEC 8473-1:1998, Information technology – Protocol for providing the connectionless-mode network service: Protocol specification. | +| [ANSI INCITS 230] | ANSI INCITS 230-1994 (R1999), Information Technology – Fibre Channel – Physical and Signaling Interface (FC-PH). | +| [ANSI INCITS 296] | ANSI INCITS 296-1997 (R2007), Information Technology – Single-Byte Command Code Sets CONnection (SBCON) Architecture. | +| [EN 50083-9] | EN 50083-9:2002, Cable networks for television signals, sound signals and interactive services – Part 9: Interfaces for CATV/SMATV headends and similar professional equipment for DVB/MPEG-2 transport streams. | +| [ETSI TR 101 290] | ETSI TR 101 290 (2014), Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems. | +| [IETF RFC 791] | IETF RFC 791 (1981), Internet Protocol. | +| [IETF RFC 1661] | IETF RFC 1661 (1994), The Point-to-Point Protocol (PPP). | +| [IETF RFC 1662] | IETF RFC 1662 (1994), PPP in HDLC-like Framing. | +| [IETF RFC 2460] | IETF RFC 2460 (1998), Internet Protocol, Version 6 (IPv6) Specification. | +| [IETF RFC 3032] | IETF RFC 3032 (2001), MPLS Label Stack Encoding. | +| [IEEE 802.3] | IEEE 802.3-2015, IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications. | +| [IEEE 802.17] | IEEE 802.17-2011, IEEE standard for information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 17: Resilient packet ring (RPR) access method and physical layer specifications. | +| [ISO 9542] | ISO 9542:1988, Information processing systems – Telecommunications and information exchange between systems – End system to Intermediate system routeing exchange protocol for use in conjunction with the Protocol for providing the connectionless-mode network service (ISO 8473). | +| [ISO/IEC 10589] | ISO/IEC 10589:2002, Information technology – Telecommunications and information exchange between systems – Intermediate System to Intermediate System intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO 8473). | + +- [ISO/IEC 13239] ISO/IEC 13239:2002, *Information technology – Telecommunications and information exchange between systems – High-level data link control (HDLC) procedures.* +- [ISO/IEC 13818-9] ISO/IEC 13818-9:1996, *Information technology – Generic coding of moving pictures and associated audio information – Part 9: Extension for real time interface for systems decoders.* +- [ISO/IEC 14165-241] ISO/IEC 14165-241:2005, *Information technology – Fibre Channel – Part 241: Backbone 2 (FC-BB-2).* + +# 3 Terms and definitions + +This Recommendation defines the following terms: + +**3.1 channel identifier (CID):** An 8-bit binary number used to indicate one of 256 communication channels at a generic framing procedure (GFP) initiation/termination point. + +**3.2 client data frame:** A generic framing procedure (GFP) frame that contains payload data from a client signal. + +**3.3 client defect clear indication (DCI):** A fast explicit indication from the client that a client signal fail, reverse defect or forward defect event has cleared. The DCI allows the generic framing procedure (GFP) sink adaptation function to respond to the fault clearing immediately rather than detecting the clearing through a time out in the arrival of Client Signal Fail (CSF), reverse defect indication (RDI) or forward defect indication (FDI) frames. + +**3.4 client forward defect indication (FDI):** A generic framing procedure (GFP) client management frame (CMF) used to communicate client forward defect information from the GFP-F source to the sink adaptation functions. Some clients transmit an indication of local faults affecting the forward signal direction, with the indication encoded into the client physical layer signal. + +**3.5 client management frame (CMF):** A generic framing procedure (GFP) frame containing information associated with the management of the GFP connection between the GFP source and sink. + +**3.6 client reverse defect indication (RDI):** A generic framing procedure (GFP) client management frame (CMF) used to communicate this client reverse defect information from the GFP-F source to the sink adaptation functions. Some clients transmit an indication of faults in the reverse signal direction, with the indication encoded into the client physical layer signal. + +**3.7 control frame:** A generic framing procedure (GFP) frame used to control the GFP connection. The only control defined at this time is the idle frame. + +**3.8 frame-mapped GFP:** A type of generic framing procedure (GFP) mapping in which a client signal frame is received and mapped in its entirety into one GFP frame. + +**3.9 management communications frame (MCF):** A generic framing procedure (GFP) frame used to provide a management communications channel (MCC) capability across the GFP link. The definition of this channel and its applications are beyond the scope of this Recommendation. + +**3.10 maximum transmission unit (MTU):** Maximum size of the generic framing procedure (GFP) payload area, in octets. + +**3.11 running disparity (RD):** A procedure used by block line codes, such as 8B/10B, to balance the total of number of 1s and 0s transmitted over time. The running disparity at the end of a line code sub-block is positive if more 1s than 0s have been sent up to that point, and negative if more 0s than 1s have been sent. The encoder uses the running disparity value to choose which of the two possible codes to transmit for the next character mapping in order to balance the number of transmitted 1s and 0s. + +**3.12 source port/destination port (SP/DP):** A logical addressable entity on a physical interface. + +**3.13 superblock:** A transparent generic framing procedure (GFP) structure that combines multiple 64B/65B codes along with a CRC-16 for the purposes of providing payload octet alignment and error control over the bits in the superblock. + +NOTE – See Figure 8-3. + +**3.14 transparent GFP:** A type of generic framing procedure (GFP) mapping in which block-coded client characters are decoded and then mapped into a fixed-length GFP frame and may be transmitted immediately without waiting for the reception of an entire client data frame. + +# **4 Abbreviations and acronyms** + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|---------------------------------------| +| 1GbE | 1 Gbit/s Ethernet | +| ACFC | Address-and-Control-Field-Compression | +| AIS | Alarm Indication Signal | +| ASI | Asynchronous Serial Interface | +| ATM | Asynchronous Transfer Mode | +| BBW | Backbone WAN | +| cHEC | core Header Error Check | +| CID | Channel Identifier | +| CLNP | Connectionless Network Protocol | +| CMF | Client Management Frame | +| CoS | Class of Service | +| CRC | Cyclic Redundancy Check | +| CSF | Client Signal Fail | +| DCI | Defect Clear Indication | +| DE | Discard Eligibility | +| DP | Destination Port | +| DVB | Digital Video Broadcast | +| eHEC | extension Header Error Check | +| ES-IS | End System-to-Intermediate System | +| EOF | End of Frame | +| ESCON | Enterprise Systems Connection | +| EXI | Extension header Identifier | +| FC | Fibre Channel | +| FCS | Frame Check Sequence | +| FDI | Forward Defect Indication | +| FEFI | Far-End Fault Indication | +| FICON | Fibre Connection | + +| | | +|-------|-----------------------------------------------------------------------------------------| +| FIFO | First-In, First-Out | +| GFP | Generic Framing Procedure | +| GFP-F | Generic Framing Procedure, Frame-mapped | +| GFP-T | Generic Framing Procedure, Transparent | +| HDLC | High-level Data Link Control | +| HEC | Header Error Check | +| IFG | Inter-Frame Gap | +| IP | Internet Protocol | +| IPG | Inter-Packet Gap | +| ISDN | Integrated Services Digital Network | +| IS-IS | Intermediate System-to-Intermediate System | +| LCC | Last Control Character | +| LCP | Link Control Protocol | +| LF | Local Fault | +| LOL | Loss of Light | +| LOS | Loss of Signal | +| LSB | Least Significant Bit | +| MAC | Media Access Control | +| MAPOS | Multiple Access Protocol Over Synchronous optical network/synchronous digital hierarchy | +| MCC | Management Communications Channel | +| MCF | Management Communications Frame | +| MPEG | Moving Picture Expert Group | +| MPLS | Multiprotocol Label Switching | +| MSB | Most Significant Bit | +| MTU | Maximum Transmission Unit | +| NE | Network Element | +| OSI | Open Systems Interconnection | +| OTN | Optical Transport Network | +| PCS | Physical Coding Sublayer | +| PDH | Plesiochronous Digital Hierarchy | +| PDU | Protocol Data Unit | +| pFCS | payload Frame Check Sequence | +| PFI | Payload Frame check sequence Indicator | +| PLI | Payload Length Indicator | +| PLL | Phase-Locked Loop | +| PPP | Point-to-Point Protocol | +| PTI | Payload Type Identifier | + +| | | +|--------------|------------------------------------------| +| PTP | Precision Time Protocol | +| RD | Running Disparity | +| RDI | Reverse Defect Indication | +| RF | Remote Fault | +| RPR | Resilient Packet Ring | +| RS | Reed-Solomon | +| SBCON | Single-Byte command code sets Connection | +| SBW | Spare Bandwidth | +| SDH | Synchronous Digital Hierarchy | +| SFD | Start of Frame Delimiter | +| SOF | Start of Frame | +| SONET | Synchronous Optical Network | +| SP | Source Port | +| SSF | Server Signal Failure | +| SSM | Synchronization Status Message | +| tHEC | type Header Error Check | +| TS | Transport Stream | +| TSF | Trail Signal Fail | +| UPI | User Payload Identifier | +| VC- n | Virtual Container- n | + +# 5 Conventions + +**Transmission order:** The order of transmission of information in all the figures in this Recommendation is first from left to right and then from top to bottom. Within each byte, the most significant bit (MSB) is transmitted first. The MSB is shown at the left of all the figures. + +**Undefined field values:** The default value for any undefined header fields is 0, unless otherwise stated. + +# 6 Aspects common to both frame-mapped and transparent-mapped modes of GFP + +This clause discusses the common (protocol-independent) aspects of GFP for octet-aligned payloads. The mapping of the framed payloads into an SDH VC-*n* is specified in [ITU-T G.707]. The mapping of the framed payloads into an OTN ODUk payload is specified in [ITU-T G.709]. + +GFP uses a variation of the HEC-based frame delineation mechanism defined for asynchronous transfer mode (ATM) (see [ITU-T I.432.1]). Two kinds of GFP frames are defined: GFP client frames and GFP control frames. Frame formats for GFP client and control frames are defined in clauses 6.1 and 6.2. GFP also supports a flexible (payload) header extension mechanism to facilitate the adaptation of GFP for use with diverse transport mechanisms. Currently defined payload extension header types are specified in clause 6.1.2.1.3. + +## 6.1 Basic signal structure for GFP client frames + +The format for GFP frames is shown in Figure 6-1. GFP frames are octet-aligned and consist of a GFP core header and, except for GFP idle frames, a GFP payload area. + +![Diagram showing the basic signal structure of a GFP frame. It consists of a 'Core header' (4 octets) and a 'Payload area' (4-65535 octets). The 'Octet transmission order' is indicated by a downward arrow on the left, numbered 1 to n. The 'Bit transmission order' is indicated by a rightward arrow at the bottom, numbered 1 to 8.](724c7777b608e53be38b12b6fb3c43bc_img.jpg) + +Octet transmission order + +1 2 3 4 5 . . . n + +Core header + +4 + +Payload area + +4-65535 + +1 2 3 4 5 6 7 8 → Bit transmission order + +Diagram showing the basic signal structure of a GFP frame. It consists of a 'Core header' (4 octets) and a 'Payload area' (4-65535 octets). The 'Octet transmission order' is indicated by a downward arrow on the left, numbered 1 to n. The 'Bit transmission order' is indicated by a rightward arrow at the bottom, numbered 1 to 8. + +a) Frame size and transmission order + +![Diagram showing the fields constituting a GFP client frame. The 'Core header' is expanded to show '16-bit payload length indicator' and 'cHEC (CRC-16)'. The 'Payload area' is expanded to show 'Payload headers (4-64 bytes)', 'Client payload information field', and 'Optional payload FCS (CRC-32)'.](75f0cb39f1cd165dfe4a6aa6c4d9388d_img.jpg) + +Core header + +16-bit payload length indicator + +cHEC (CRC-16) + +Payload area + +Payload headers (4-64 bytes) + +Client payload information field + +Optional payload FCS (CRC-32) + +Diagram showing the fields constituting a GFP client frame. The 'Core header' is expanded to show '16-bit payload length indicator' and 'cHEC (CRC-16)'. The 'Payload area' is expanded to show 'Payload headers (4-64 bytes)', 'Client payload information field', and 'Optional payload FCS (CRC-32)'. + +b) Field constituting a GFP client frame + +G.7041-Y.1303(11)\_F6-1 + +**Figure 6-1 – Frame format for GFP client frames** + +### 6.1.1 GFP core header + +The GFP core header format is shown in Figure 6-2. The four octets of the GFP core header consist of a 16-bit payload length indicator (PLI) field and a 16-bit core header error check (cHEC) field. This header allows GFP frame delineation independent of the content of the higher layer PDUs. + +![](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +*Octet transmission order* + +↓ + +| | | | +|---|-------------|---------| +| 1 | PLI | <15:08> | +| 2 | PLI | <7:00> | +| 3 | cHEC | <15:08> | +| 4 | cHEC | <7:00> | + +1 2 3 4 5 6 7 8 → *Bit transmission order* + +G.7041-Y.1303(11)\_F6-2 + +**Figure 6-2 – GFP core header format** + +#### 6.1.1.1 Payload length indicator field + +The two-octet PLI field contains a binary number representing the number of octets in the GFP payload area. The absolute minimum value of the PLI field in a GFP client frame is four octets. PLI values 0–3 are reserved for GFP control frame usage (see clause 6.2). + +#### 6.1.1.2 Core header error control field + +The two-octet cHEC field contains a cyclic redundancy check-16 (CRC-16) error control code that protects the integrity of the contents of the core header by enabling both single-bit error correction and multi-bit error detection. The cHEC sequence is calculated over the octets of the core header as specified in clause 6.1.1.2.1. + +##### 6.1.1.2.1 HEC processing + +The header error check (HEC) generating polynomial is $G(x) = x^{16} + x^{12} + x^5 + 1$ , with an initialization value of zero, where $x^{16}$ corresponds to the MSB and $x^0$ corresponds to the least significant bit (LSB). + +The cHEC field is generated by the source adaptation process using the following steps (see Appendix I of [b-ITU-T V.41]). + +- 1) The first two octets of the GFP frame are taken in network octet order, MSB first, to form a 16-bit pattern representing the coefficients of a polynomial $M(x)$ of degree 15. +- 2) $M(x)$ is multiplied by $x^{16}$ and divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ of degree 15 or less. +- 3) The coefficients of $R(x)$ are considered to be a 16-bit sequence, where $x^{15}$ is the MSB. +- 4) This 16-bit sequence is the CRC-16 where the first bit of the CRC-16 to be transmitted is the coefficient of $x^{15}$ and the last bit transmitted is the coefficient of $x^0$ . + +The sink adaptation process performs steps 1)–3) in the same manner as the source adaptation process, except that here, the $M(x)$ polynomial of step 1) includes the CRC-16 bits in received order, and has degree 23. In the absence of bit errors, the remainder shall be 0000 0000 0000 0000. + +This single error correction shall be performed on the core header. The GFP sink adaptation process shall discard any of those GFP frames where multi-bit errors are detected. The sink adaptation process also updates any relevant system records for performance monitoring purposes. + +#### 6.1.1.3 Core header scrambling + +The core header is scrambled for DC balance by an exclusive-OR operation (modulo 2 addition) with the hexadecimal number B6AB31E0. This number is the maximum transition, minimum side-lobe, Barker-like sequence of length 32. The scrambling of the GFP core header improves the robustness of the GFP frame delineation procedure and provides a sufficient number of 0-1 and 1-0 transitions during idle transmission periods. + +### 6.1.2 GFP payload area + +The GFP payload area, which consists of all octets in the GFP frame after the GFP core header, is used to convey higher-layer specific protocol information. This variable length area may include from 4 to 65 535 octets. As shown in Figure 6-3, the GFP payload area consists of two common components: a payload header and a payload information field. An optional payload frame check sequence (pFCS) field is also supported. + +![Diagram of GFP payload area format showing octet transmission order and bit transmission order.](2cde062fd82833415971a8bd1a2cafab_img.jpg) + +The diagram illustrates the structure of the GFP payload area. It shows three main components stacked vertically: a 'Payload header' (octets 5 to 8), a 'Payload information field' (octets 9 to n), and an optional 'Payload FCS' (octets n-3 to n). The 'Payload header' has a variable length X, ranging from 4 to 64 octets. The 'Payload information field' has a variable length ranging from 0 to 65535 - X octets. The 'Payload FCS' is an optional 4-octet field. The diagram also indicates the 'Octet transmission order' (vertical arrow pointing down) and the 'Bit transmission order' (horizontal arrow pointing right). The reference G.7041-Y.1303(11)\_F6-3 is noted at the bottom right. + +Diagram of GFP payload area format showing octet transmission order and bit transmission order. + +Figure 6-3 – GFP payload area format + +Practical GFP maximum transmission unit (MTU) sizes for the GFP payload area are application specific. An implementation should support transmission and reception of GFP frames with GFP payload areas of at least 2 000 octets. By prior arrangement, consenting GFP implementations may use other MTU values. Implementations supporting frame-mapped fibre channel (FC) should support GFP payload areas of at least 2 156 octets. + +#### 6.1.2.1 Payload header + +The payload header is a variable-length area, 4 to 64 octets long, intended to support data link management procedures specific to the higher-layer client signal. The structure of the GFP payload header is illustrated in Figure 6-4. The area contains two mandatory fields, the type and the type header error check (tHEC) fields, and a variable number of additional payload header fields. This group of additional payload header fields is referred to as the extension header. The presence of the extension header, and its format, and the presence of the optional pFCS are specified by the type field. The tHEC protects the integrity of the type field. + +![Diagram of GFP payload header format showing octets 5 to n. Octet 5 is 'Type', octet 6 is 'tHEC', octets 7-9 are 'Extension header field', and octet n is 'eHEC'. Bit transmission order is shown from 1 to 8 at the bottom. Vertical arrows on the right indicate sizes: 2 for Type, 2 for tHEC, 0 to 60 for Extension header field, and 2 for eHEC.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +*Octet transmission order* + +G.7041-Y.1303(11)\_F6-4 + +Diagram of GFP payload header format showing octets 5 to n. Octet 5 is 'Type', octet 6 is 'tHEC', octets 7-9 are 'Extension header field', and octet n is 'eHEC'. Bit transmission order is shown from 1 to 8 at the bottom. Vertical arrows on the right indicate sizes: 2 for Type, 2 for tHEC, 0 to 60 for Extension header field, and 2 for eHEC. + +**Figure 6-4 – GFP payload header format** + +An implementation shall support reception of a GFP frame with a payload header of any length in the range 4 to 64 octets. + +##### 6.1.2.1.1 GFP type field + +The GFP type field is a mandatory two-octet field of the payload header that indicates the content and format of the GFP payload information field (see clause 6.1.2.2). The type field distinguishes between GFP frame types and between different services in a multi-service environment. As shown in Figure 6-5, the type field consists of a payload type identifier (PTI), a pFCS indicator (PFI), an extension header identifier (EXI) and a user payload identifier (UPI). + +![Diagram of GFP type field format. Octet 5 contains PTI (bits 15-13), PFI (bit 12), and EXI (bits 11-8). Octet 6 contains UPI (bits 7-0). Bit transmission order is shown from 1 to 8 at the bottom. Bit numbers 15-8 are shown above octet 5, and 7-0 are shown below octet 5.](9cd90f495b95ad2116ff780248c26d95_img.jpg) + +*Octet transmission order* + +G.7041-Y.1303(11)\_F6-5 + +Diagram of GFP type field format. Octet 5 contains PTI (bits 15-13), PFI (bit 12), and EXI (bits 11-8). Octet 6 contains UPI (bits 7-0). Bit transmission order is shown from 1 to 8 at the bottom. Bit numbers 15-8 are shown above octet 5, and 7-0 are shown below octet 5. + +**Figure 6-5 – GFP type field format** + +The interpretation of the UPI field for PTI values different from 000 or 100 is for further study. Sample type field values are illustrated in Appendix II. + +###### 6.1.2.1.1.1 Payload type identifier + +This 3-bit subfield of the type field identifies the type of GFP client frame. Three kinds of client frames are currently defined, user data frames (PTI = 000), CMFs (PTI = 100) and management communication frames (PTI = 101). PTI codepoints are given in Table 6-1. + +**Table 6-1 – GFP payload type identifiers** + +| Type bits <15:13> | Usage | +|-------------------|---------------------------| +| 000 | User data | +| 100 | Client management | +| 101 | Management communications | +| Others | Reserved | + +###### 6.1.2.1.1.2 Payload frame check sequence indicator + +This one-bit subfield of the type field indicates the presence (PFI = 1) or absence (PFI = 0) of the pFCS field. + +###### 6.1.2.1.1.3 Extension header identifier (EXI) + +This 4-bit subfield of the type field identifies the type of extension header GFP. Three kinds of extension headers are currently defined: a null extension header; a linear extension header; and a ring extension header. EXI codepoints are given in Table 6-2. + +**Table 6-2 – GFP extension header identifiers** + +| Type bits <11:8> | Usage | +|------------------|-----------------------| +| 0000 | Null extension header | +| 0001 | Linear frame | +| 0010 | Ring frame | +| Others | Reserved | + +###### 6.1.2.1.1.4 User payload identifier + +This 8-bit field identifies the type of payload conveyed in the GFP payload information field. Interpretation of the UPI field is relative to the type of GFP client frame as indicated by the PTI subfield. UPI values for client data frames are specified in clause 6.1.3.1 and UPI values for CMFs are specified in clause 6.1.3.2. + +##### 6.1.2.1.2 Type header error control field + +The two-octet tHEC field contains a CRC-16 error control code that protects the integrity of the contents of the type field by enabling both single-bit error correction and multi-bit error detection. The type header consists of the type field and the tHEC. + +The content of the tHEC field is generated using the same steps as the cHEC (see clause 6.1.1.2.1) with the following exception: + +- for the tHEC, step 1 is modified such that $M(x)$ is formed from all the octets in the type field, excluding the tHEC field itself at the source, but including the tHEC field at the sink. + +The GFP sink adaptation process shall perform single-bit error correction on the type field, which is protected by a tHEC field. The GFP sink adaptation process shall discard any of those GFP frames where multi-bit errors are detected. The sink adaptation process also updates any relevant system records for performance monitoring purposes. + +##### 6.1.2.1.3 GFP extension headers + +The payload extension header is a 0-to-60 octet extended field [including the extension header error check (eHEC)] that supports technology-specific data link headers such as virtual link identifiers, source/destination addresses, port numbers, class of service (CoS) and extension header error control. The type of the extension header is indicated by the content of the EXI bits in the type field of the payload header. + +Three extension header variants are currently defined to support client-specific data over a logical ring or logical point-to-point (linear) configurations. + +This clause describes the various fields in each extension header. The default value for any undefined fields is 0 unless otherwise stated. + +###### 6.1.2.1.3.1 Null extension header + +The payload header for a frame with a null extension header is shown in Figure 6-6. This extension header applies to a logical point-to-point configuration. It is intended for scenarios where the transport path is dedicated to one client signal. + +![](5445597cceefaca1ac89e710fe339325_img.jpg) + +*Octet transmission order* + +↓ + +| | | | +|---|------|---------| +| 5 | Type | <15:08> | +| 6 | Type | <7:00> | +| 7 | tHEC | <15:08> | +| 8 | tHEC | <7:00> | + +1 2 3 4 5 6 7 8 → *Bit transmission order* + +G.7041-Y.1303(11)\_F6-6 + +**Figure 6-6 – Payload header for a GFP frame with a null extension header** + +###### 6.1.2.1.3.2 Extension header for a linear frame + +The payload header for a linear (point-to-point) frame with an extension header, shown in Figure 6-7, is intended for scenarios where there are several independent links requiring aggregation on to a single transport path. + +![](2eb23c2210154279f8013a1594fbcc5a_img.jpg) + +*Octet transmission order* + +↓ + +| | | | +|----|-------|---------| +| 5 | Type | <15:08> | +| 6 | Type | <7:00> | +| 7 | tHEC | <15:08> | +| 8 | tHEC | <7:00> | +| 9 | CIDe | <7:00> | +| 10 | Spare | <7:00> | +| 11 | eHEC | <15:08> | +| 12 | eHEC | <7:00> | + +1 2 3 4 5 6 7 8 → *Bit transmission order* + +G.7041-Y.1303(11)\_F6-7 + +**Figure 6-7 – Payload header for a linear (point-to-point) frame including the extension header** + +###### 6.1.2.1.3.2.1 Channel ID field + +The CID is an 8-bit binary number used to indicate one of 256 communication channels at a GFP termination point. + +###### 6.1.2.1.3.2.2 Spare field + +The 8-bit spare field is reserved for future use. + +###### 6.1.2.1.3.2.3 Extension header error check field + +See clause 6.1.2.1.4. + +###### 6.1.2.1.3.3 Extension header for a ring frame + +For further study. + +##### 6.1.2.1.4 Extension header error check field + +The two-octet eHEC field contains a CRC-16 error control code that protects the integrity of the contents of the extension headers by enabling both single-bit error correction (optional) and multi-bit error detection. + +The content of the eHEC field is generated using the same steps as the cHEC (see clause 6.1.1.2.1) with the following exception: + +- for the eHEC, step 1 is modified such that $M(x)$ is formed from all the octets in the extension header, but excluding the eHEC field itself. + +The GFP sink adaptation process may perform single-bit error correction on all of the fields protected by a tHEC field. Single error correction is optional for the extension header. The GFP sink adaptation process shall discard any of those GFP frames where multi-bit errors are detected or where any error occurs in a header field that does not make use of single error correction. The sink adaptation process also updates any relevant system records for performance monitoring purposes. + +#### 6.1.2.2 Payload information field + +The payload information field contains the framed PDU for frame-mapped GFP or, in the case of transparent GFP, a group of client signal characters. This variable-length field may include from 0 to $65\,535 - X$ octets, where $X$ is the size of the payload header. This field may include an optional pFCS field. The client PDU/signal is always transferred into the GFP payload information field as an octet-aligned packet stream. + +##### 6.1.2.2.1 Payload frame check sequence field + +The GFP pFCS, as shown in Figure 6-8, is an optional, four-octet long, FCS. It contains a CRC-32 sequence that protects the contents of the GFP payload information field. The FCS generation process is defined in clause 6.1.2.2.1.1. A value of 1 in the PFI bit within the type field identifies the presence of the pFCS field. + +![Diagram of GFP payload frame check sequence format showing four octets of pFCS with their bit ranges and transmission orders.](5fbb4f0de01736f1293333e599410c99_img.jpg) + +Octet transmission order +↓ + +| | | +|------|---------| +| pFCS | <31:24> | +| pFCS | <23:16> | +| pFCS | <15:08> | +| pFCS | <7:00> | + +1 2 3 4 5 6 7 8 —→ *Bit transmission order* + +G.7041-Y.1303(11)\_F6-8 + +Diagram of GFP payload frame check sequence format showing four octets of pFCS with their bit ranges and transmission orders. + +**Figure 6-8 – GFP payload frame check sequence format** + +###### 6.1.2.2.1.1 Payload frame check sequence generation + +The pFCS is generated using the CRC-32 generating polynomial [ISO/IEC 13239] $G(x) = x^{32} + x^{26} + x^{23} + x^{22} + x^{16} + x^{12} + x^{11} + x^{10} + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + 1$ , where $x^{32}$ corresponds to the MSB and $x^0$ corresponds to the LSB. + +The pFCS field is generated using the following steps. + +- 1) The $N$ octets from the GFP payload information field, excluding the FCS are taken in network octet order, MSB first, to form a $8N$ -bit pattern representing the coefficients of a polynomial $M'(x)$ of degree $8N - 1$ . + +- 2) $M'(x)$ is multiplied by $x^{32}$ , added to the product of $x^{8N}$ and the all-1s polynomial $U(x) = 1 + x^1 + x^2 + \dots + x^{31}$ , and divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ of degree 31 or less. + +NOTE – The addition of $x^{8N} [1 + x^1 + x^2 + \dots + x^{31}]$ is equivalent to presetting the shift register to all-1s for typical shift register implementations using presets. Either method is equivalent to complementing the 32 MSBs of the GFP payload information field for the purpose of calculating the FCS. + +- 3) The coefficients of $R(x)$ are considered to be a 32-bit sequence, where $x^{31}$ is the MSB. +4) The complement of this 32-bit sequence is the CRC-32. + +The sink adaptation process performs steps 1)–3) in the same manner as the source adaptation process. In the absence of errors, the remainder shall be 11000111\_00000100\_11011101\_01111011, in the order $x^{31}$ to $x^0$ . + +#### 6.1.2.3 Payload area scrambling + +Scrambling of the GFP payload area is required to provide security if the payload information happens to be the same as the scrambling word (or its inverse) from a frame-synchronous scrambler, such as those used in the SDH Reed-Solomon (RS) layer or in an OTN OPU $k$ channel. Figure 6-9 illustrates the scrambler and descrambler processes. + +![Figure 6-9 shows two diagrams illustrating the scrambling and descrambling processes for GFP. The left diagram shows the scrambling process: an input signal X(t) is added to the output of a 43-bit shift register (labeled 'x^43 + 1' scrambler) to produce the scrambled output Y(t). The shift register consists of 43 delay elements (D1, D2, ..., D43) connected in series, with the output of D43 fed back to the input of D1. The right diagram shows the descrambling process: the scrambled input Y(t) is added to the output of a 43-bit shift register (labeled 'x^43 + 1' descrambler) to produce the descrambled output X(t). The shift register consists of 43 delay elements (D1, D2, ..., D43) connected in series, with the output of D43 fed back to the input of D1. Both diagrams include a label 'G.7041-Y.1303(11)_F6-9'.](5793a44ffdadd039928e2f9fe6daae06_img.jpg) + +Figure 6-9 shows two diagrams illustrating the scrambling and descrambling processes for GFP. The left diagram shows the scrambling process: an input signal X(t) is added to the output of a 43-bit shift register (labeled 'x^43 + 1' scrambler) to produce the scrambled output Y(t). The shift register consists of 43 delay elements (D1, D2, ..., D43) connected in series, with the output of D43 fed back to the input of D1. The right diagram shows the descrambling process: the scrambled input Y(t) is added to the output of a 43-bit shift register (labeled 'x^43 + 1' descrambler) to produce the descrambled output X(t). The shift register consists of 43 delay elements (D1, D2, ..., D43) connected in series, with the output of D43 fed back to the input of D1. Both diagrams include a label 'G.7041-Y.1303(11)\_F6-9'. + +Figure 6-9 – $x^{43}+1$ scrambler and descrambler processes for GFP + +All octets in the GFP payload area are scrambled using a $1 + x^{43}$ self-synchronous scrambler. Scrambling is done in network bit order. + +At the source adaptation process, scrambling is enabled starting at the first transmitted octet after the cHEC field, and is disabled after the last transmitted octet of the GFP frame. When the scrambler or descrambler is disabled, its state is retained. Hence, the scrambler or descrambler state at the beginning of a GFP frame payload area will thus be the last 43 payload area bits of the GFP frame transmitted in that channel immediately prior to the current GFP frame. + +The activation of the sink adaptation process descrambler also depends on the present state of the cHEC check algorithm: + +- a) in the HUNT and PRESYNC states, the descrambler is disabled; +b) in the SYNC state, the descrambler is enabled only for the octets between the cHEC field and the end of the candidate GFP frame. + +NOTE – The GFP sink adaptation process can reliably forward GFP frames to the higher-layer entity only when the sink adaptation process is in the SYNC state. + +### 6.1.3 GFP client frames + +Two types of GFP client frames are currently defined, client data and client management. GFP client data frames are used to transport data from the client signal. GFP CMFs are used to transport information associated with the management of the client signal or GFP connection. + +#### 6.1.3.1 Client data frames + +Client data is transported over GFP using client data frames. Client data frames are GFP client frames consisting of a core header and a payload area. The type field of the client data frames uses the following Type subfield values: + +- PTI = 000 +- PFI = Payload specific +- EXI = Payload specific +- UPI = Payload specific + +The PFI shall be set as required depending on whether FCS is enabled or not. The EXI shall be set consistently with the frame multiplexing and topology requirements for the GFP connection. The UPI shall be set according to the transported client signal type. Defined UPI values for client data frames are given Table 6-3. + +**Table 6-3 – User payload identifiers for GFP client frames** + +| PTI = 000 and 101 (See Notes 2 and 3) | | +|----------------------------------------------|-------------------------------------------------------------------------------------------| +| Type bits <7:0> | GFP frame payload area | +| 0000 0000
and
1111 1111 | Reserved and not available | +| 0000 0001 | Frame-mapped Ethernet | +| 0000 0010 | Frame-mapped PPP | +| 0000 0011 | Transparent fibre channel | +| 0000 0100 | Transparent FICON | +| 0000 0101 | Transparent ESCON/SBCON | +| 0000 0110 | Transparent Gbit Ethernet | +| 0000 0111 | Reserved for future use | +| 0000 1000 | Frame-mapped multiple access protocol over SDH (MAPOS) | +| 0000 1001 | Transparent DVB ASI | +| 0000 1010 | Framed-mapped IEEE 802.17 resilient packet ring | +| 0000 1011 | Frame-mapped fibre Channel FC-BBW | +| 0000 1100 | Asynchronous transparent fibre channel | +| 0000 1101 | Frame-mapped MPLS | +| 0000 1110 | See Note 6 | +| 0000 1111 | Frame-mapped OSI network layer protocols (IS-IS, ES-IS, CLNP) | +| 0001 0000 | Frame-mapped IPv4 | +| 0001 0001 | Frame-mapped IPv6 | +| 0001 0010 | Frame-mapped DVB ASI | +| 0001 0011 | Frame-mapped 64B/66B encoded Ethernet, including the Ethernet frame preamble (see Note 4) | +| 0001 0100 | Frame-mapped 64B/66B encoded Ethernet ordered set information (see Note 5) | +| 0001 0101 | Transparent transcoded FC-1200 (see clause 17.8.2 of [ITU-T G.709]) | + +**Table 6-3 – User payload identifiers for GFP client frames** + +| PTI = 000 and 101 (See Notes 2 and 3) | | +|----------------------------------------------|-------------------------------------------------------------| +| Type bits <7:0> | GFP frame payload area | +| 0001 0110 | Precision time protocol (PTP) message | +| 0001 0111 | Synchronization status message (see clause 7.11 and Note 7) | +| 0001 1000
through
1110 1111 | Reserved for future standardization | +| 1111 0000
through
1111 1110 | Reserved for proprietary use (See Note 1) | + +NOTE 1 – The use of proprietary code values is described in Annex A of [ITU-T G.806]. +NOTE 2 – The UPI value applies to the PDU in the payload area of that GFP frame. +NOTE 3 – Not all of these UPI types are applicable with PTI = 101. +NOTE 4 – The former [b-ITU-T G-Sup.43] description of this mapping recommended using UPI = 1111 1101. +NOTE 5 – The former [b-ITU-T G-Sup.43] description of this mapping recommended using UPI = 1111 1110. +NOTE 6 – This UPI value had been assigned to multicast MPLS frames, which is a mapping that is no longer applicable. This UPI value should not be used. +NOTE 7 – The same UPI is used for the both types of messages in 7.11. Both include a synchronization status message (SSM) octet, with the extended SSM appending additional message fields. + +#### 6.1.3.2 GFP client management frames + +CMFs provide a generic mechanism for the GFP client-specific source adaptation process to optionally send CMFs to the GFP client-specific sink adaptation process. As illustrated in Figure 6-10, the CMFs are GFP client frames consisting of a core header and a payload area. The type field of the client data frames uses the following Type subfield values: + +- PTI = 100 +- PFI = Payload specific +- EXI = Payload specific +- UPI = Payload specific + +![Diagram of GFP client management frame structure showing octet and bit transmission orders, core header, payload header, extension header, payload area, and optional FCS.](7133ccf78043568ca62ecbcd43628a4a_img.jpg) + +Octet transmission order + +| | | | | | | | | | | | +|------|------------------|-----|-----|-----|--|--|--|---|----------------|-----------------------------| +| 1 | Length | | | | | | | | 2 | Core header | +| 2 | cHEC | | | | | | | | 2 | | +| 3 | PTI | PFI | EXI | UPI | | | | 2 | Payload header | | +| 4 | tHEC | | | | | | | | | 2 | +| 5 | Extension header | | | | | | | | | 0-58 | +| 6 | eHEC | | | | | | | | 2 | Extension header (optional) | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | Payload area | +| 9-66 | | | | | | | | | | | +| +1 | | | | | | | | | | | +| +2 | | | | | | | | | | | +| +3 | | | | | | | | | | | +| +4 | | | | | | | | | | | +| +5 | | | | | | | | | | | +| +6 | | | | | | | | | | | +| +7 | | | | | | | | | | | +| +8 | | | | | | | | | | | +| +9 | | | | | | | | | | FCS (optional) | +| +n | | | | | | | | | | | +| +n+1 | | | | | | | | | | | +| +n+2 | | | | | | | | | | | +| +n+3 | | | | | | | | | | FCS (optional) | +| +n+4 | | | | | | | | | | | + +1 2 3 4 5 6 7 8 → Bit transmission order + +G.7041-Y.1303(11)\_F6-10 + +Diagram of GFP client management frame structure showing octet and bit transmission orders, core header, payload header, extension header, payload area, and optional FCS. + +**Figure 6-10 – GFP client management frame** + +For use as a GFP CMF, the PFI shall be set as required depending on whether FCS is enabled [note that the use of FCS in GFP CMFs reduces the amount of spare bandwidth (SBW) that can be used for such frames]. The extension header indicator (EXI) shall be set as required depending on whether the extension header is employed (note that the use of an extension header in the GFP CMF will significantly reduce the amount of SBW that can be used for such frames). + +The UPI defines the use of the GFP CMF payload. In this way, the GFP CMF may be used for multiple purposes. Table 6-4 defines the GFP CMF payload uses. + +**Table 6-4 – GFP client management frame user payload identifier** + +| PTI = 100 | | +|-------------------------------------------------------------------------------------|--------------------------------------------------------| +| UPI value | Usage | +| 0000 0000
1111 1111 | Reserved | +| 0000 0001 | Client signal fail (loss of client signal) | +| 0000 0010 | Client signal fail (loss of character synchronization) | +| 0000 0011 | Client defect clear indication (DCI) | +| 0000 0100 | Client forward defect indication (FDI) | +| 0000 0101 | Client reverse defect indication (RDI) | +| 0000 0110
through
1101 1111 | Reserved for future use | +| 1110 0000
through
1111 1110 | Reserved for proprietary use
(Note) | +| NOTE – The use of proprietary code values is described in Annex A of [ITU-T G.806]. | | + +## 6.2 GFP control frames + +GFP control frames are used in the management of the GFP connection. The only control frame specified at this time is the GFP idle frame. + +### 6.2.1 GFP idle frames + +The GFP idle frame is a special four-octet GFP control frame consisting of only a GFP core header with the PLI and cHEC fields (see clause 6.1.1) set to 0, and no payload area. The idle frame is intended for use as a filler frame for the GFP source adaptation process to facilitate the adaptation of the GFP octet stream to any given transport medium where the transport medium channel has a higher capacity than required by the client signal. The GFP idle frame format is shown in Figure 6-11, with the parenthetical values indicating the values after the Barker-like scrambling has been performed. + +![Diagram of GFP idle frame structure showing octet transmission order (1-4) and bit transmission order (1-8) for each octet. The octets are: 1: 00 (B6) hex, 2: 00 (AB) hex, 3: 00 (31) hex, 4: 00 (E0) hex.](392a79ccd95e682ccd08f35ab2e64144_img.jpg) + +*Octet transmission order* + +| | | +|---|-------------| +| 1 | 00 (B6) hex | +| 2 | 00 (AB) hex | +| 3 | 00 (31) hex | +| 4 | 00 (E0) hex | + +1 2 3 4 5 6 7 8 → *Bit transmission order* + +G.7041-Y.1303(11)\_F6-11 + +Diagram of GFP idle frame structure showing octet transmission order (1-4) and bit transmission order (1-8) for each octet. The octets are: 1: 00 (B6) hex, 2: 00 (AB) hex, 3: 00 (31) hex, 4: 00 (E0) hex. + +**Figure 6-11 – GFP idle frame (Barker-like scrambled frame)** + +### 6.2.2 Other control frames + +Control frames with PLI = 1, 2 or 3 are for further study. + +## 6.3 GFP frame-level functions + +This clause discusses frame-level processes common to all payloads that are framed via GFP. Processes specific to particular payloads are discussed in clauses 7 and 8. The relationships among these processes are illustrated in Figure 6-12. + +![Figure 6-12: GFP common (protocol-independent) procedures. The diagram shows two main processes: Frame multiplex and Frame demultiplex. Frame multiplex takes inputs from client-specific source adaptation processes, client management, and idle insert, and outputs to a core header scrambler and a payload scrambler, which then output to octet streams to/from payload mapping. Frame demultiplex takes inputs from octet streams to/from payload mapping, which pass through a payload descrambler and a core header check, and then output to client-specific sink adaptation processes, client management, and idle termination.](a149b400127a3e3e50b3c98d27c5935c_img.jpg) + +The diagram illustrates the GFP common (protocol-independent) procedures. It is divided into two main sections: Frame multiplex and Frame demultiplex. + +**Frame multiplex:** On the left, inputs include "Octet streams from client-specific source adaptation processes" (indicated by a bracket and vertical dots), "Client management", and "Idle insert". These inputs enter a "Frame multiplex" block. The output of the multiplex block splits into two parallel blocks: "Core header scrambler" and "Payload scrambler". The outputs of these two blocks merge and are labeled "Octet streams to/from payload mapping". + +**Frame demultiplex:** On the right, the "Octet streams to/from payload mapping" enter a "Payload descrambler" block. The output of the descrambler enters a "Core header check" block. The output of the check block then splits into two paths: one leading to "Octet streams to client-specific sink adaptation processes" (indicated by a bracket and vertical dots), and another leading to "Client management" and "Idle termination". These final outputs enter a "Frame demultiplex" block. + +A reference code "G.7041-Y.1303(11)\_F6-12" is located at the bottom right of the diagram. + +Figure 6-12: GFP common (protocol-independent) procedures. The diagram shows two main processes: Frame multiplex and Frame demultiplex. Frame multiplex takes inputs from client-specific source adaptation processes, client management, and idle insert, and outputs to a core header scrambler and a payload scrambler, which then output to octet streams to/from payload mapping. Frame demultiplex takes inputs from octet streams to/from payload mapping, which pass through a payload descrambler and a core header check, and then output to client-specific sink adaptation processes, client management, and idle termination. + +**Figure 6-12 – GFP common (protocol-independent) procedures** + +### 6.3.1 GFP frame delineation algorithm + +The GFP uses a modified version of the HEC algorithm specified in clause 7.3.3.2 of [ITU-T I.432.1] to provide GFP frame delineation. The frame delineation algorithm used in the GFP differs from that in [ITU-T I.432.1] in two basic ways: + +- a) the algorithm uses the PLI field of the GFP core header to find the end of the GFP frame; and +- b) HEC field calculation uses a 16-bit polynomial and, consequently, generates a two-octet cHEC field. + +GFP frame delineation is performed based on the correlation between the first two octets of the GFP frame and the embedded two-octet cHEC field. There are two alternative frame delineation methods, 6.3.1.1 and 6.3.1.2. + +#### 6.3.1.1 Frame delineation alternative using only the core header + +Figure 6-13 shows the state diagram for the GFP frame delineation method based on only using the core header. + +The state diagram works as follows: + +- 1) In the HUNT state, the GFP process performs frame delineation by searching, octet-by-octet, for a correctly formatted core header over the last received sequence of four octets. The core header single error correction is disabled while in this state. Once a correct cHEC match is detected in the candidate PLI and cHEC fields, a candidate GFP frame is identified and the receive process enters the PRESYNC state. + +- 2) In the PRESYNC state, the GFP process performs frame delineation by checking, frame-by-frame, for a correct cHEC match in the presumed core header of the next candidate GFP frame. The PLI field in the core header of the preceding GFP frame is used to find the beginning of the next candidate GFP frame. Core header single error correction remains disabled while in this state. The process repeats until DELTA consecutive correct cHECs are confirmed, at which point the process enters the SYNC state. If an incorrect cHEC is detected, the process returns to the HUNT state. The total number of consecutive correct cHECs required to move from the HUNT state to the SYNC state is therefore DELTA + 1. +- 3) In the SYNC state, the GFP process performs frame delineation by checking for a correct cHEC match on the next candidate GFP frame. The PLI field in the core header of the preceding GFP frame is used to find the beginning of the next candidate GFP frame. Single-bit core header error correction is enabled while in this state. Frame delineation is lost whenever multiple bit errors are detected in the core header by the cHEC. In this case, a GFP loss of frame delineation event is declared, the framing process returns to the HUNT state, and a client server signal failure (SSF) is indicated to the client adaptation process. +- 4) Idle GFP frames participate in the delineation process and are then discarded. + +![Figure 6-13 – GFP frame delineation state diagram. The diagram shows three main states: PRESYNC, HUNT, and SYNC. PRESYNC is shown in two groups: 'Frame-by-frame (error correction disabled)' and 'Frame-by-frame (error correction enabled)'. The 'Frame-by-frame (error correction disabled)' group contains multiple PRESYNC sub-states (cHEC_ID, cHEC_11, etc.) and a 'Virtual framers (up to M)' block. Transitions from these PRESYNC sub-states to HUNT are labeled 'Correct cHEC' and 'Incorrect cHEC'. The 'Frame-by-frame (error correction enabled)' group contains PRESYNC sub-states (cHEC_MD, cHEC_M1, etc.). Transitions from these PRESYNC sub-states to HUNT are labeled 'Correct cHEC' and 'Incorrect HEC (multi-bit-errors)'. Transitions from HUNT to PRESYNC sub-states are labeled 'Correct cHEC'. A transition from SYNC to HUNT is labeled 'Incorrect HEC (multi-bit-errors)'. A transition from PRESYNC (error correction enabled) to SYNC is labeled 'Delta consecutive correct cHECs'. Below the diagram, 'Octet-by-octet (error correction disabled)' and 'Frame-by-frame (error correction enabled)' are labeled. The reference 'G.7041-Y.1303(11)_F6-13' is at the bottom right.](d17aa1fcc3b86503ad1dd0717a6c34c2_img.jpg) + +Figure 6-13 – GFP frame delineation state diagram. The diagram shows three main states: PRESYNC, HUNT, and SYNC. PRESYNC is shown in two groups: 'Frame-by-frame (error correction disabled)' and 'Frame-by-frame (error correction enabled)'. The 'Frame-by-frame (error correction disabled)' group contains multiple PRESYNC sub-states (cHEC\_ID, cHEC\_11, etc.) and a 'Virtual framers (up to M)' block. Transitions from these PRESYNC sub-states to HUNT are labeled 'Correct cHEC' and 'Incorrect cHEC'. The 'Frame-by-frame (error correction enabled)' group contains PRESYNC sub-states (cHEC\_MD, cHEC\_M1, etc.). Transitions from these PRESYNC sub-states to HUNT are labeled 'Correct cHEC' and 'Incorrect HEC (multi-bit-errors)'. Transitions from HUNT to PRESYNC sub-states are labeled 'Correct cHEC'. A transition from SYNC to HUNT is labeled 'Incorrect HEC (multi-bit-errors)'. A transition from PRESYNC (error correction enabled) to SYNC is labeled 'Delta consecutive correct cHECs'. Below the diagram, 'Octet-by-octet (error correction disabled)' and 'Frame-by-frame (error correction enabled)' are labeled. The reference 'G.7041-Y.1303(11)\_F6-13' is at the bottom right. + +**Figure 6-13 – GFP frame delineation state diagram** + +Robustness against false delineation in the re-synchronization process depends on the value of DELTA. A value of DELTA = 1 is suggested. + +Frame delineation acquisition speed can be improved by the implementation of multiple "virtual framers", whereby the GFP process remains in the HUNT state and a separate PRESYNC sub-state is spawned for each candidate GFP frame detected in the incoming octet stream, as depicted in Figure 6-13. + +#### 6.3.1.2 Frame delineation alternative using both the core and type headers + +An alternative algorithm uses both the core and type headers, as illustrated in Figure 6-14. This algorithm can be advantageous for high-speed interfaces that are typically protected by FEC and where circuit implementations often use wide data bus structures. The state machine works similarly to that shown in Figure 6-13, except for the PRESYNC state operation. That operation works as follows: + +- In the PRESYNC state, the four octets following the candidate cHEC are checked: + - if the candidate cHEC corresponds to a GFP Idle frame (i.e., PLI=0), and the subsequent four octets contain a valid cHEC, proceed to the SYNC state; + - if the candidate cHEC does not correspond to a GFP Idle frame (i.e., PLI≠0), and the subsequent four octets contain a valid tHEC, proceed to the SYNC state; + - otherwise, go back to the HUNT state. + +Error correction continues to be disabled for both the core and type headers during this state. The tHEC check requires retaining the 43 data bits immediately prior to the candidate cHEC, so that the tHEC value can be properly descrambled. + +![Figure 6-14 – GFP frame delineation state diagram using cHEC and tHEC. The diagram shows three states: HUNT, PRESYNC, and SYNC. Transitions are based on cHEC and tHEC checks. HUNT to PRESYNC is labeled 'Correct cHEC'. PRESYNC to HUNT is labeled 'Incorrect cHEC or tHEC'. PRESYNC to SYNC is labeled 'Correct tHEC or second consecutive cHEC'. SYNC to HUNT is labeled 'Incorrect cHEC (multiple bit errors)'. Above the PRESYNC state is the text 'Frame-by-frame (error correction disabled)'. Below the HUNT state is 'Octet-by-octet (error correction disabled)'. Below the SYNC state is 'Frame-by-frame (error correction enabled)'. A reference code 'G.7041-Y.1303(16)_F6-14' is at the bottom right.](dcb5711d118ae6753b0e12f86eda37db_img.jpg) + +``` + +stateDiagram-v2 + [*] --> HUNT + HUNT --> PRESYNC : Correct cHEC + PRESYNC --> HUNT : Incorrect cHEC or tHEC + PRESYNC --> SYNC : Correct tHEC or second consecutive cHEC + SYNC --> HUNT : Incorrect cHEC (multiple bit errors) + + note for PRESYNC "Frame-by-frame (error correction disabled)" + note for HUNT "Octet-by-octet (error correction disabled)" + note for SYNC "Frame-by-frame (error correction enabled)" + +``` + +G.7041-Y.1303(16)\_F6-14 + +Figure 6-14 – GFP frame delineation state diagram using cHEC and tHEC. The diagram shows three states: HUNT, PRESYNC, and SYNC. Transitions are based on cHEC and tHEC checks. HUNT to PRESYNC is labeled 'Correct cHEC'. PRESYNC to HUNT is labeled 'Incorrect cHEC or tHEC'. PRESYNC to SYNC is labeled 'Correct tHEC or second consecutive cHEC'. SYNC to HUNT is labeled 'Incorrect cHEC (multiple bit errors)'. Above the PRESYNC state is the text 'Frame-by-frame (error correction disabled)'. Below the HUNT state is 'Octet-by-octet (error correction disabled)'. Below the SYNC state is 'Frame-by-frame (error correction enabled)'. A reference code 'G.7041-Y.1303(16)\_F6-14' is at the bottom right. + +**Figure 6-14 – GFP frame delineation state diagram using cHEC and tHEC** + +NOTE – The choice between the frame delineation algorithm alternatives is left to the implementer and shall not be a provisional option. Equipment developed prior to the 2012 version of this Recommendation used the frame delineation algorithm method based on only using the core header. Equipment developed subsequently may use either alternative. + +### 6.3.2 Frame multiplexing + +GFP frames from multiple ports and multiple client types are multiplexed on a frame-by-frame basis. The choice of scheduling algorithms is outside the scope of this Recommendation. + +When there are no other GFP frames available for transmission, GFP idle frames shall be inserted, thus providing a continuous stream of frames for mapping into an octet-aligned physical layer. + +### 6.3.3 Client signal fail and defect indications + +The GFP provides a generic mechanism for a GFP client-specific source adaptation process to propagate indications of a client signal fail (CSF) or a local or remote client defect to the far-end GFP client-specific sink-adaptation process on detection of the condition. + +#### 6.3.3.1 Client signal fail indication + +Detection rules for CSF events are, by definition, client-specific (see clauses 7 and 8). Upon detection, a GFP source adaptation process should generate a CMF (PTI = 100). The PFI subfield is set to 0 (no payload information field FCS) and the EXI subfield is set to the appropriate extension header type as applicable. The two types of CSF use the following UPI field values: + +- loss of client signal (UPI = 0000 0001); +- loss of client character synchronization (UPI = 0000 0010). + +Upon detection of the CSF condition, the GFP client-specific source adaptation process should send CSF indications to the far-end GFP client-specific sink adaptation process once every $100 \text{ ms} \leq T \leq 1\,000 \text{ ms}$ , beginning as soon as possible. When no client frames are available, GFP idle frames shall be transmitted before and between CSF frames. + +Upon reception of the CSF indication, the GFP client sink adaptation process declares a sink CSF. Defect handling is discussed in clause 6.3.4. + +The GFP client-specific sink adaptation process should clear the defect condition upon one of the following conditions: + +- 1) no CSF frame is received in $N \times 1\,000 \text{ ms}$ (a value of 3 is suggested for $N$ ); or +- 2) upon receiving a valid GFP client data frame; or +- 3) upon receiving a DCI. + +Handling of incomplete GFP frames at the onset of a CSF event should be consistent with the error handling procedures specified in clause 8.3 for transparent-mapped GFP and in clause 7.4 for frame-mapped GFP. The use of CSF with frame-mapped GFP is client-specific, as specified in clause 7. + +#### 6.3.3.2 Client link fault status indications + +Two types of GFP CMF frames are defined to communicate the explicit client fault indication signals:1 + +- client reverse defect indication (RDI); +- client forward defect indication (FDI). + +Detection rules for local and remote defect indications are client-specific and specified in clause 7. The format of these client link fault status signals is specified in the associated standards for the client signal. Upon detection of the explicit forward (reverse) client link fault status signal, the GFP client-specific source adaptation process should send an FDI (RDI) signal to the far-end GFP client-specific sink adaptation process. The FDI/RDI signal shall be sent once every $100 \text{ ms} \leq T \leq 1\,000 \text{ ms}$ , beginning as soon as possible. When no client frames are available, GFP idle frames shall be transmitted before and between FDI and RDI frames. + +Upon reception of the FDI (RDI) signal, the GFP client sink adaptation process should regenerate the native forward (reverse) client link fault status signal towards the near-end client port to communicate the remote client link fault status information to the near-end client signal sink. The format of the egress client fault status signal is specified in the associated standards for that client signal interface. + +The GFP client-specific sink adaptation process should clear the defect condition upon one of the following conditions: + +- 1) no FDI (RDI) CMF frames are received in $N \times 1\,000 \text{ ms}$ (a value of 3 is suggested for $N$ ); or +- 2) receiving a valid GFP client data frame; or +- 3) receiving a DCI. + +For the FDI and RDI, the PFI subfield is set to 0 (no payload information field FCS) and the EXI subfield is set to the appropriate extension header type, as applicable. + +The process of client link fault status propagation is illustrated in Figure 6-15 (reverse fault) and Figure 6-16 (forward fault). The figures depict a typical link connection scenario between two client network elements (NE A and NE D) interconnected through a generic transport network. Client NE A connects to transport node NE B and client NE D connects to transport node NE C. Figure 6-15 depicts a scenario where client NE A detects a link fault in the D-to-A receive path and transmits a + +--- + +1 Note that neither loss of client signal nor loss of client synchronization are considered "explicit" client fault indications, since they are detected by the GFP client-specific source adaptation process. + +well-defined client (reverse) link fault status indication for the reverse path over the A-to-D link connection towards NE D. Similarly, Figure 6-16 depicts a scenario where client NE D detects a link fault in its D-to-A transmit path and transmits a well-defined client (forward) link fault status indication for the transmit path over the D-to-A link connection towards NE A. The client link fault status indications are propagated by GFP-capable NEs by mapping the signalled client link fault indications into a corresponding RDI (Figure 6-15) or FDI (Figure 6-16) GFP CMF frame. + +![Figure 6-15: Examples of a reverse defect indication of a client link fault status indication. The diagram shows four nodes: NE A, NE B, NE C, and NE D. NE A is on the left, and NE D is on the right. A red dashed line with an arrow pointing right from NE A to NE B is labeled 'RFI' (Remote Fault Indication). A red 'X' is on the line between NE A and NE B. A blue arrow pointing left from NE B to NE C is labeled 'CMF/RDI'. A red dashed line with an arrow pointing right from NE C to NE D is labeled 'RFI'. A bracket between NE B and NE C is labeled 'GFP/CMF reverse defect indication'. A bracket between NE C and NE D is labeled 'Regenerated client remote fault indication (RFI)'. A legend at the bottom shows a grey triangle pointing right labeled 'GFP process (and associated server trail)'. The text 'G.7041-Y.1303(16)_F6-15' is in the bottom right.](5d3455c6c2a37cb3aff761fedeb8644e_img.jpg) + +Figure 6-15: Examples of a reverse defect indication of a client link fault status indication. The diagram shows four nodes: NE A, NE B, NE C, and NE D. NE A is on the left, and NE D is on the right. A red dashed line with an arrow pointing right from NE A to NE B is labeled 'RFI' (Remote Fault Indication). A red 'X' is on the line between NE A and NE B. A blue arrow pointing left from NE B to NE C is labeled 'CMF/RDI'. A red dashed line with an arrow pointing right from NE C to NE D is labeled 'RFI'. A bracket between NE B and NE C is labeled 'GFP/CMF reverse defect indication'. A bracket between NE C and NE D is labeled 'Regenerated client remote fault indication (RFI)'. A legend at the bottom shows a grey triangle pointing right labeled 'GFP process (and associated server trail)'. The text 'G.7041-Y.1303(16)\_F6-15' is in the bottom right. + +**Figure 6-15 – Examples of a reverse defect indication of a client link fault status indication** + +![Figure 6-16: Examples of a forward defect indication of a client link fault status indication. The diagram shows four nodes: NE A, NE B, NE C, and NE D. NE A is on the left, and NE D is on the right. A red dashed line with an arrow pointing left from NE D to NE C is labeled 'LFI' (Local Fault Indication). A red 'X' is on the line between NE C and NE D. A blue arrow pointing right from NE C to NE B is labeled 'CMF/FDI'. A red dashed line with an arrow pointing left from NE B to NE A is labeled 'LFI'. A bracket between NE B and NE C is labeled 'GFP/CMF forward defect indication'. A bracket between NE A and NE B is labeled 'Regenerate client local fault indication (LFI)'. A legend at the bottom shows a grey triangle pointing right labeled 'GFP process (and associated server trail)'. The text 'G.7041-Y.1303(16)_F6-16' is in the bottom right.](00504fc688ebcf131ccbeff94dfc9939_img.jpg) + +Figure 6-16: Examples of a forward defect indication of a client link fault status indication. The diagram shows four nodes: NE A, NE B, NE C, and NE D. NE A is on the left, and NE D is on the right. A red dashed line with an arrow pointing left from NE D to NE C is labeled 'LFI' (Local Fault Indication). A red 'X' is on the line between NE C and NE D. A blue arrow pointing right from NE C to NE B is labeled 'CMF/FDI'. A red dashed line with an arrow pointing left from NE B to NE A is labeled 'LFI'. A bracket between NE B and NE C is labeled 'GFP/CMF forward defect indication'. A bracket between NE A and NE B is labeled 'Regenerate client local fault indication (LFI)'. A legend at the bottom shows a grey triangle pointing right labeled 'GFP process (and associated server trail)'. The text 'G.7041-Y.1303(16)\_F6-16' is in the bottom right. + +**Figure 6-16 – Examples of a forward defect indication of a client link fault status indication** + +For instance, in Figure 6-15, the native client link fault status indication at transport node NE B is received by the GFP source adaptation process, mapped into a CMF RDI and then forwarded to the GFP sink adaptation process in transport node NE C. At NE C, the CMF RDI is extracted, mapped back into native client link fault status indication and regenerated in the port towards the near-end client NE D. Similarly, in Figure 6-16, the native client link fault status indication at transport node NE C is forwarded to the GFP source adaptation process, mapped into a CMF FDI client link fault status and then forwarded to the GFP sink process in transport node NE B. At NE B, the CMF FDI is extracted, mapped into the native client link fault status indication and regenerated back in the port toward NE A. + +Note that processing of native client link fault status indications and its mapping into a GFP CMF for client link fault status indication can be based solely on near-end client link fault status information. + +#### 6.3.3.3 Client defect clear indications + +In addition to the implicit defect clearance mechanisms in clause 6.3.3, the GFP also provides an explicit event-driven mechanism to help expedite clearance of native client link fault conditions called the client defect clear indication (DCI). + +Clearance rules for native client link fault events are client-specific. + +Upon detection of the native client link fault clearance event condition, the GFP client-specific source adaptation process may send a DCI signal to the GFP client-specific sink adaptation process. The + +DCI should be sent as soon as possible upon detection of the defect clearing. Subsequent DCI frames may be transmitted. Interim frames shall be GFP idle frames when no client data frames are available. + +Upon reception of the DCI signal, the GFP client sink adaptation process should stop inserting the native reverse (forward) client link fault clearance signal. If the standard for the associated client signal interface specifies a link fault clearance signal, the GFP client sink adaptation process should regenerate and transmit it to the near-end client port. + +### 6.3.4 Defect handling in GFP + +Figure 6-17 depicts the causal relationship between various defects detected or indicated by the GFP process. Trail signal fail (TSF) events refer to failure events detected in the SDH or OTN transport network as defined in [ITU-T G.783] and [ITU-T G.798]. GFP server signal fail events refer to GFP loss of frame delineation events as defined in the GFP state machine (clause 6.3.1) or propagation of TSF events to the GFP clients. CSF events refer to failure events detected in the client signal on ingress (communicated to the far-end by a CSF CMF) or egress (client-specific mapping defects such as payload errors, see clauses 7 and 8). + +![Figure 6-17: Defect signal propagation in GFP. The diagram shows two stacks of layers representing the Ingress and Egress client processes. The Ingress stack has four layers: Ingress client process (top, with a red X), GFP client-specific source adaptation process, GFP common process (client source adaptation), and Transport network (bottom). The Egress stack has four layers: Egress client process (top), GFP client-specific sink adaptation process (with a red X), GFP common process (client sink adaptation) (with a red X), and Transport network (bottom, with a red X). Arrows indicate defect signal propagation: from the Ingress client process down through the layers, and from the Transport network up through the layers to the Egress client process. Labels CSF, SSF, and TSF are on the right, corresponding to the layers: CSF points to the GFP client-specific sink adaptation process, SSF points to the GFP common process (client sink adaptation), and TSF points to the Transport network. A dashed line connects the Ingress client process to the Egress client-specific sink adaptation process. A small text 'G.7041-Y.1303(16)_F6-17' is at the bottom right.](9f9386d5b3d6cbeb1ed104a799320ebf_img.jpg) + +Figure 6-17: Defect signal propagation in GFP. The diagram shows two stacks of layers representing the Ingress and Egress client processes. The Ingress stack has four layers: Ingress client process (top, with a red X), GFP client-specific source adaptation process, GFP common process (client source adaptation), and Transport network (bottom). The Egress stack has four layers: Egress client process (top), GFP client-specific sink adaptation process (with a red X), GFP common process (client sink adaptation) (with a red X), and Transport network (bottom, with a red X). Arrows indicate defect signal propagation: from the Ingress client process down through the layers, and from the Transport network up through the layers to the Egress client process. Labels CSF, SSF, and TSF are on the right, corresponding to the layers: CSF points to the GFP client-specific sink adaptation process, SSF points to the GFP common process (client sink adaptation), and TSF points to the Transport network. A dashed line connects the Ingress client process to the Egress client-specific sink adaptation process. A small text 'G.7041-Y.1303(16)\_F6-17' is at the bottom right. + +**Figure 6-17 – Defect signal propagation in GFP** + +Upon detection of a TSF event or a GFP loss of frame delineation event, the GFP sink adaptation process generates a GFP SSF indication to its client-specific sink adaptation processes. These failure events are cleared as soon as the GFP process regains link synchronization. + +Upon detection of CSF events other than a far-end CSF indication, the GFP client-specific sink adaptation processes should take client-specific (as well as server-specific) actions to deal with those failure events. + +## 6.4 Management communications frame + +Management communications frames (MCFs), which use PTI = 101, are used to provide an in-band management communications channel (MCC) capability between a GFP source and sink. The type of PDUs carried in these frames are identified by the UPI values specified in Table 6-3. The MCFs are for further study. + +# 7 Payload-specific aspects for frame-mapped GFP + +This clause describes those aspects of the generic encapsulation specific to the adaptation of client signals using a frame-by-frame mapping of the client payload into GFP. + +## 7.1 Ethernet media access control payload + +The format of Ethernet media access control (MAC) frames is defined in clause 3.1 of [IEEE 802.3]. There is a one-to-one mapping between a higher-layer PDU and a GFP PDU. Specifically, the boundaries of the GFP PDU are aligned with boundaries of the framed higher layer PDUs. This relationship between Ethernet MAC frames and GFP frames is illustrated in Figure 7-1. + +![Diagram showing the relationship between an Ethernet MAC frame and a GFP frame. The Ethernet MAC frame consists of Preamble (7 octets), Start of frame delimiter (1 octet), Destination address (DA) (6 octets), Source address (SA) (6 octets), Length/type (2 octets), MAC client data (0-60 octets), Pad (0-4 octets), and Frame check sequence (FCS) (4 octets). The GFP frame consists of PLI (2 octets), cHEC (2 octets), Type (2 octets), tHEC (2 octets), GFP extension header (0-60 octets), and GFP payload. The GFP payload contains the Ethernet MAC frame from DA to FCS. Bit numbering is shown at the bottom: 1-8 for the first octet, 1-8 for the second octet, etc.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +| Ethernet MAC frame | | Octets | GFP frame | +|--------------------|-----------------------------------|--------|-----------------------------| +| | | 2 | PLI | +| | | 2 | cHEC | +| | | 2 | Type | +| | | 2 | tHEC | +| Octets | | 0-60 | GFP extension header | +| 7 | Preamble | | GFP payload | +| 1 | Start of frame delimiter | | | +| 6 | Destination address (DA) | | | +| 6 | Source address (SA) | | | +| 2 | Length/type | | | +| | MAC client data | | | +| | Pad | | | +| 4 | Frame check sequence (FCS) | | | +| | 1 2 3 4 5 6 7 8 Bits | | 1 2 3 4 5 6 7 8 Bits | + +G.7041-Y.1303(11)\_F7-1 + +Diagram showing the relationship between an Ethernet MAC frame and a GFP frame. The Ethernet MAC frame consists of Preamble (7 octets), Start of frame delimiter (1 octet), Destination address (DA) (6 octets), Source address (SA) (6 octets), Length/type (2 octets), MAC client data (0-60 octets), Pad (0-4 octets), and Frame check sequence (FCS) (4 octets). The GFP frame consists of PLI (2 octets), cHEC (2 octets), Type (2 octets), tHEC (2 octets), GFP extension header (0-60 octets), and GFP payload. The GFP payload contains the Ethernet MAC frame from DA to FCS. Bit numbering is shown at the bottom: 1-8 for the first octet, 1-8 for the second octet, etc. + +**Figure 7-1 – Ethernet and GFP frame relationships** + +### 7.1.1 Ethernet media access control encapsulation + +The Ethernet MAC octets from destination address through FCS, inclusive, are placed in the GFP payload information field. Octet alignment is maintained and bit identification within octets is maintained. Specifically, on an octet-by-octet basis, bits 0 and 7 in clause 3 of [IEEE 802.3] correspond to bits 8 and 1, respectively, in this GFP Recommendation. + +### 7.1.2 Ethernet inter-packet gap deletion and restoring + +The following rules apply to the deletion and restoration of Ethernet inter-packet gaps (IPGs) when the client is not a native frame-mapped GFP client. + +- 1) IPGs are deleted before the Ethernet MAC frame is processed by the GFP source adaptation process and restored after the GFP frame is processed by the GFP sink adaptation process. +- 2) IPGs are deleted as the Ethernet MAC frame is extracted from the client bit stream. The extracted (decoded) Ethernet MAC frame is then forwarded to the GFP source adaptation process for subsequent encapsulation into a GFP frame. +- 3) IPGs are restored after the Ethernet MAC frame is extracted from the GFP frame by the GFP termination element. The extracted (uncoded) Ethernet MAC frame is then forwarded to the client layer for subsequent processing. IPGs are restored by ensuring that sufficient octets containing an idle pattern of 00 hex are present between consecutive received Ethernet MAC frames to meet the minimum receiver inter-frame gap (IFG) requirements. Minimum receiver IFG requirements are stated in clause 4.4 of [IEEE 802.3]. + +### 7.1.3 Client-specific signal fail aspects + +Clauses 7.1.3.1 to 7.1.3.6 identify various client link fault conditions and define actions that should be taken at client signal egress in response to a corresponding CMF signal, or any client adaptation or transport defects that make it impossible to regenerate a client signal. + +NOTE – For further details of processing these signals and consequent action, refer to [ITU-T G.8021] and [ITU-T G.806]. + +#### 7.1.3.1 Common aspects for Ethernet clients + +Upon detection of a loss of client signal by the GFP source adaptation process, CSF (loss of client signal) is transmitted until the client signal is restored, as described in clause 6.3.3.1. + +Upon detection of a loss of client synchronization by the GFP source adaptation process, CSF (loss of client synchronization) is transmitted until character synchronization is regained, as described in clause 6.3.3.1. + +NOTE – The insertion of RDI and FDI CMFs is specific to certain IEEE 802.3 physical layers, and is only applicable for GFP-F. + +#### **7.1.3.2 10BASE-FB client** + +The remote fault (RF) signal is defined in clause 17 of [IEEE 802.3]. When this signal is detected by the GFP source adaptation process, it causes CMF RDI frames to be inserted until the RF signal is no longer detected, as described in clause 6.3.3.2. When CMF RDI is received by the GFP sink adaptation process, it causes the RF signal to be output on the egress client signal. + +#### **7.1.3.3 100BASE-FX client or 100Base-TX over shielded twisted pair client** + +The far-end fault indication (FEFI) is defined in clauses 24.3.2.1 and 24.3.4 of [IEEE 802.3]. When this signal is detected by the GFP source adaptation process, it causes CMF RDI frames to be inserted until the FEFI signal is no longer detected, as described in clause 6.3.3.2. When CMF RDI is received by the GFP sink adaptation process, it is recommended that the FEFI signal be output on the egress client signal in order to cause far-end fault detection and the associated action at the downstream Ethernet receiver. + +When the GFP sink adaptation process receives a CSF (loss of client signal) or any other transport failure events, the client adaptation process should transmit nothing, forcing loss of signal (LOS) detection and associated action at the downstream Ethernet receiver. + +#### **7.1.3.4 10/100/1000BASE-TX over unshielded twisted pair client** + +A link enabled to support the IEEE auto-negotiation process, defined in clause 28 of [IEEE 802.3], is considered failed if it fails to reach completion of the auto-negotiation process after it has started. The common behaviour for LOS described in clause 7.1.3.1 applies. + +#### **7.1.3.5 1000BASE-X client** + +Gigabit Ethernet physical media dependent (PMD) signal detect requirements are specified in clauses 38.2.4 and 39.2.3 of [IEEE 802.3] for fibre and copper interfaces, respectively. Conditions for declaring a client signal in or out of 8B/10B codeword synchronization are specified in clause 36.2.5.2.6 and Figure 36-9 of [IEEE 802.3]. + +When the GFP sink adaptation process receives a CSF (loss of client signal) or any other transport failure events, the GFP adaptation sink process should transmit nothing, forcing LOS detection and associated action at the downstream 1 Gbit/s Ethernet (1GbE) receiver. + +A link enabled to support the IEEE auto-negotiation process, defined in clause 37 of [IEEE 802.3], is considered failed if it fails to reach completion of the auto-negotiation process after it has started. The common behaviour for LOS described in clause 7.1.3.1 applies. + +When the GFP sink adaptation process receives a CSF (loss of character synchronization), it is recommended that the egress 1GbE transmitter continuously output the /V/ ordered set per clause 36.2.4.16 of [IEEE 802.3]. Alternatively, in response to the CSF (loss of character synchronization) condition, the client adaptation process may transmit nothing, forcing LOS detection and associated action at the downstream 1GbE receiver. + +#### **7.1.3.6 10G client** + +The local fault (LF) and RF signals are defined in clause 46.3.4 of [IEEE 802.3]. + +When the RF signal is detected by the GFP source adaptation process, it causes CMF RDI frames to be inserted until the RF signal is no longer detected, as described in clause 6.3.3.2. When CMF RDI + +is received by the GFP sink adaptation process, it is recommended that the RF signal be output on the 10 Gbit Ethernet egress client signal. + +When the LF signal is detected by the GFP source adaptation process, it causes CMF FDI frames to be inserted until the LF signal is no longer detected, as described in clause 6.3.3.2. When a CMF FDI is received by the GFP sink adaptation process, it is recommended that the LF signal be output on the 10 Gbit Ethernet egress client signal. + +Note that clause 46.3.4.3 of [IEEE 802.3] specifies that the LF or RF should go away within 0.7 µs of the fault clearing. Consequently, it is appropriate to send a DCI immediately after detecting that the link is healthy again. + +10GBASE-R client signals use ordered sets to communicate detected remote and LF indications. The 10GBASE-R mapping specified in this clause (UPI = 0000 0001) does not preserve ordered set information and consequently communicates the 10GBASE-R remote and LF information between the GFP source and sink through GFP CMF RDI and FDI frames. The 10GBASE-R mapping specified in 7.9 (UPI = 0001 0011 and 0001 0100) preserves the ordered set information. Consequently, it does not use GFP CMF RDI or FDI frames, but passes the client signal's ordered sets for this purpose. + +## 7.2 HDLC/PPP payload + +The direct mapping of high-level data link control/point-to-point protocol (HDLC/PPP) into GFP is intended for applications that wish to transport HDLC/PPP frames in their native mode. HDLC/PPP payloads are natively encapsulated into an HDLC-like frame. The format of a PPP frame is defined in clause 2 of [IETF RFC 1661]. The format of the HDLC-like frame is defined in clause 3 of [IETF RFC 1662]. Unlike [IETF RFC 1662], no octet stuffing procedure is performed to identify flag or control escape characters during the GFP adaptation process. There is a one-to-one mapping between a higher-layer PPP/HDLC PDU and a GFP PDU. Specifically, the boundaries of the GFP PDU are aligned with boundaries of the framed higher layer HDLC/PPP PDUs. This relationship between the HDLC/PPP frame and the GFP frame is illustrated in Figure 7-2. + +Similar clients, such as MAPOS, are mapped in the same manner as PPP frames. + +![](875c6f4f441fdd3ca7e1908fd1582983_img.jpg) + +| PPP/HDLC frame | | Octets | GFP frame | | +|----------------|-----------------------------------|--------|-----------|-----------------------------| +| | | 2 | | PLI | +| | | 2 | | cHEC | +| | | 2 | | Type | +| | | 2 | | tHEC | +| Octets | | 0-60 | | GFP extension header | +| 1 | Flag | | | GFP payload | +| 1 | Address | | | | +| 1 | Control | | | | +| 2 | PPP type | | | | +| | PPP information | | | | +| | (Pad) | | | | +| 4 | Frame check sequence (FCS) | | | | +| | 1 2 3 4 5 6 7 8 Bits | | | 1 2 3 4 5 6 7 8 Bits | + +G.7041-Y.1303(1-)\_F7-2 + +**Figure 7-2 – HDLC/PPP and GFP frame relationships** + +### 7.2.1 PPP frame encapsulation + +All octets from the PPP/HDLC frame, including any optional PPP information field padding, are placed in the payload information field of a GFP frame. Octet alignment is maintained and bit identification within octets is also maintained. Bits 0 and 7 of the PPP/HDLC byte (see [ISO/IEC 13239]) correspond to bits 8 and 1 of the GFP payload byte, respectively. + +### 7.2.2 GFP/HDLC delineation interworking + +GFP does not rely on flag characters, and associated control escape octet, for frame delineation purposes. The following rules apply to the processing of octet-synchronous HDLC frames by a GFP/HDLC interworking function: + +- 1) Flags and associated control escape octets are removed (as specified in clause 4.2 of [IETF RFC 1662]) as the PPP/HDLC frame is extracted from the incoming client octet stream. The extracted (decoded) PPP/HDLC frame is then forwarded to the GFP source adaptation process for subsequent encapsulation into a GFP frame. +- 2) The GFP extracts the PPP/HDLC frame from the GFP frame. The extracted (uncoded) PPP/HDLC frame is then forwarded to the client layer for subsequent processing. Flags and control escape characters are then restored by inserting flag characters (e.g., hexadecimal 0x7e) and escape control characters (e.g., hexadecimal 0x7d) as specified in clause 4 of [IETF RFC 1662]. + +### 7.2.3 PPP payload configuration options + +Modifications to the PPP/HDLC-like frame format may be negotiated using the link control protocol (LCP) configuration option procedures as defined in clause 6 of [IETF RFC 1661]. For example, the format of the GFP frame after a successful negotiation of the address-and-control-field-compression (ACFC) configuration option is illustrated in Figure 7-3. Such configuration procedures are client-specific and transparent to the GFP process. + +![Diagram showing the mapping of a PPP/HDLC-like frame into a GFP frame. The PPP/HDLC frame consists of a protocol field, information field, optional padding, and FCS. These are encapsulated into the GFP payload. The GFP frame also includes PLI, cHEC, Type, tHEC, and an extension header.](315bdbeafb39026e19b77c26b19d9d1f_img.jpg) + +| PPP/HDLC-like frame | | Octets | GFP frame | | +|-----------------------------|-------------------------------|---------------|-----------------------------|--| +| | | 2 | PLI | | +| | | 2 | cHEC | | +| | | 2 | Type | | +| | | 2 | tHEC | | +| | | 0-60 | GFP extension header | | +| Octets | PPP protocol | | GFP
payload | | +| 1-2 | PPP information | | | | +| 1 | PPP padding (optional) | | | | +| 2
4 | PPP/HDLC FCS | | | | +| 1 2 3 4 5 6 7 8 Bits | | | 1 2 3 4 5 6 7 8 Bits | | + +G.7041-Y.1303(11)\_F7-3 + +Diagram showing the mapping of a PPP/HDLC-like frame into a GFP frame. The PPP/HDLC frame consists of a protocol field, information field, optional padding, and FCS. These are encapsulated into the GFP payload. The GFP frame also includes PLI, cHEC, Type, tHEC, and an extension header. + +**Figure 7-3 – PPP/HDLC and GFP frame relationships (with PPP's ACFC configuration option)** + +## 7.3 Fibre channel payload via FC-BBW\_SONET + +The format of an FC broadband-2\_SONET (FC-BBW\_SONET) PDU is defined in clause 6 of [ISO/IEC 14165-241]. For the purposes of GFP-F-based adaptation, a one-to-one mapping is assumed between FC PDUs and FC-BBW\_SONET PDUs (as per the FC-BB specification), and between FC-BBW\_SONET PDUs and GFP PDU (as per this Recommendation). Only the mapping + +relationship between the FC-BBW\_SONET PDU and the GFP PDU is specified in this Recommendation. + +### 7.3.1 FC-BB-2\_SONET PDU encapsulation + +All octets in the FC-BBW\_SONET PDU, starting from the LLC/SNAP\_Header to the backbone WAN (BBW) message payload, inclusive, are placed in the payload information field of a GFP frame. Both octet alignment and bit identification within octets are maintained within the GFP PDU. The construction of the BBW\_Header and the BBW message payload (if present) for the FC-BBW\_SONET PDUs are specified in [ISO/IEC 14165-241]. This relationship between FC-BBW\_SONET frames and GFP frames is illustrated in Figure 7-4. + +![Diagram showing the mapping of FC-BB-2_SONET PDU fields to GFP frame fields. The FC-BB-2_SONET PDU consists of LLC/SNAP_Header (8 octets), BBW header (4 octets), and BBW message payload (0-2148 octets). These are mapped into the GFP frame's GFP information field, which also includes PLI (2 octets), cHEC (2 octets), Type (2 octets), tHEC (2 octets), and GFP extension header (0-60 octets).](78ff716475b2f65bf01c3a4d02d89fc4_img.jpg) + +| FC-BB-2_SONET PDU | | Octets | GFP frame | +|-------------------|---------------------|--------|----------------------| +| | | 2 | PLI | +| | | 2 | cHEC | +| | | 2 | Type | +| | | 2 | tHEC | +| | | 0-60 | GFP extension header | +| Octets | 8 | ----- | GFP information | +| | 4 | | | +| | 0-2148 | | | +| | LLC/SNAP_Header | | | +| | BBW header | | | +| | BBW message payload | | | + +1 2 3 4 5 6 7 8 Bits      1 2 3 4 5 6 7 8 Bits +G.7041-Y.1303(16)\_F7-4 + +Diagram showing the mapping of FC-BB-2\_SONET PDU fields to GFP frame fields. The FC-BB-2\_SONET PDU consists of LLC/SNAP\_Header (8 octets), BBW header (4 octets), and BBW message payload (0-2148 octets). These are mapped into the GFP frame's GFP information field, which also includes PLI (2 octets), cHEC (2 octets), Type (2 octets), tHEC (2 octets), and GFP extension header (0-60 octets). + +Figure 7-4 – Fibre channel broadband-2 SONET (FC-BBW\_SONET) and GFP frame relationships + +## 7.4 Error handling in frame-mapped GFP + +On ingress, PDUs detected in error before transmission by the client source adaptation process should be discarded. PDUs detected in error while in transmission by the client source adaptation process should be padded with an all-1s bit sequence and transmitted with a pFCS that has all 32-bits complemented, when present. These actions ensure that the termination GFP process, or the client end, will drop the errored PDU. + +### 7.4.1 Client-specific signal fail aspects + +When frame-mapped GFP source adaptation process detects a CSF at ingress, the preferred action is to output the appropriate client signal AIS if available. + +In the case where no client alarm indication signal (AIS) is available, it is possible to generate a CMF[csf] at the GFP-F source adaptation process, which may send a "client signal fail" indication as described in clause 6.3.3. Other implementation-dependent indications of a failed client signal (e.g., loss-of-clock from an interface between integrated circuits) may be encoded as client signal fail. NOTE – For further details of processing this signal and consequent action, refer to [ITU-T G.8021] and [ITU-T G.806]. + +## 7.5 IEEE 802.17 resilient packet ring payload + +The format of resilient packet ring (RPR) frames is defined in clause 8 of [IEEE 802.17]. There is a one-to-one mapping between a RPR frame and a GFP PDU. For clarity, this relationship between RPR frames and GFP frames is illustrated in Figure 7-5. + +![Diagram showing the mapping of an RPR frame into a GFP frame. The RPR frame is shown as a grey rectangle with dimensions N (Octets) and Bits (MSB to LSB). The GFP frame is shown as a table with four header fields (PLI, cHEC, Type, tHEC) and a payload field. The RPR frame is mapped into the GFP payload field. The header fields are 2 octets each. The payload field is labeled 'GFP payload' and has 8 bits per octet. The diagram is labeled G.7041-Y.1303(11)_F7-5.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +| RPR frame | | Octets | GFP frame | +|-----------|-----------|--------|-------------| +| N | RPR frame | 2 | PLI | +| | | 2 | cHEC | +| | | 2 | Type | +| | | 2 | tHEC | +| | | | GFP payload | + +Octets / Bits MSB LSB 1 2 3 4 5 6 7 8 + +G.7041-Y.1303(11)\_F7-5 + +Diagram showing the mapping of an RPR frame into a GFP frame. The RPR frame is shown as a grey rectangle with dimensions N (Octets) and Bits (MSB to LSB). The GFP frame is shown as a table with four header fields (PLI, cHEC, Type, tHEC) and a payload field. The RPR frame is mapped into the GFP payload field. The header fields are 2 octets each. The payload field is labeled 'GFP payload' and has 8 bits per octet. The diagram is labeled G.7041-Y.1303(11)\_F7-5. + +**Figure 7-5 – RPR and GFP frame relationships** + +### 7.5.1 RPR encapsulation + +All of the RPR frame octets (as defined in clause 8 of [IEEE 802.17]) are placed in the GFP payload information field. The default is no header extension and the pFCS field is not used. Octet alignment is maintained and bit identification within octets is maintained. Specifically, on an octet-by-octet basis, the LSB and MSB in clause 8 and Annex C of [IEEE 802.17] correspond to bits 8 and 1, respectively, in this GFP Recommendation. A complete definition of this encapsulation is contained in Annex C of [IEEE 802.17]. + +## 7.6 Direct mapping of multiprotocol label switching into GFP-F frames + +The direct mapping of multiprotocol label switching (MPLS) into GFP is intended for applications that wish to transport MPLS-shim PDUs directly over a transport network such as OTN, SDH, or PDH. The MPLS PDU contains one or more MPLS-specific label stack entries (as specified in [IETF RFC 3032]) and an MPLS payload information field. All octets in the MPLS PDU are placed in the payload information field of a GFP-F frame. Both octet alignment and bit identification within octets are maintained within the GFP-F PDU. This direct mapping of MPLS into GFP is intended to be the default mapping when MPLS client signals are directly carried over a transport network. + +The GFP pFCS is required and is computed as specified in clause 6.1.2.2.1.1 and inserted into the pFCS field. The PFI field is set to 1. + +This relationship between MPLS PDU and GFP-F frames is illustrated in Figure 7-6. + +![Diagram showing MPLS PDU and GFP frame relationships. The MPLS PDU consists of a label stack (one entry of 4 octets, followed by N optional entries of 4 octets each) and a payload. The GFP frame consists of a header (PLI, cHEC, Type, tHEC, and an extension header of 0-60 octets) and a payload information field that carries the MPLS PDU. The pFCS is at the end of the GFP frame. Bit and octet alignment is shown at the bottom.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +| MPLS PDU | | Octets | GFP frame | | +|----------|----------------------|--------|---------------------------|-------------------------| +| | | 2 | | PLI | +| | | 2 | | cHEC | +| | | 2 | | Type | +| | | 2 | | tHEC | +| | | 0-60 | | Extension header | +| Octets | 4 | ----- | Payload information field | | +| | N x 4 | | | | +| | 4 | | | | +| | | | | pFCS | +| | 1 2 3 4 5 6 7 8 Bits | | 1 2 3 4 5 6 7 8 Bits | | + +G.7041-Y.13C3(11)\_F7-6 + +Diagram showing MPLS PDU and GFP frame relationships. The MPLS PDU consists of a label stack (one entry of 4 octets, followed by N optional entries of 4 octets each) and a payload. The GFP frame consists of a header (PLI, cHEC, Type, tHEC, and an extension header of 0-60 octets) and a payload information field that carries the MPLS PDU. The pFCS is at the end of the GFP frame. Bit and octet alignment is shown at the bottom. + +**Figure 7-6 – MPLS PDU and GFP frame relationships** + +## **7.7 Direct mapping of IP and OSI network layer PDUs into GFP-F frames** + +The direct mapping of IPv4, IPv6 and open systems interconnection (OSI) network layer PDUs into GFP is intended for applications that wish to transport IP/OSI PDUs directly over SDH containers. The IPv4 PDU [IETF RFC 791], IPv6 PDU [IETF RFC 2460], CLNP PDU [ITU-T X.233], end system-to-intermediate system (ES-IS) PDU [ISO 9542] and intermediate system-to-intermediate system (IS-IS) PDU [ISO/IEC 10589] contain one or more client-specific header entry and a client payload information field. All octets in the client PDU are placed in the payload information field of a GFP-F frame. Both octet alignment and bit identification within octets are maintained within the GFP-F PDU. + +The GFP pFCS is required and is computed as specified in clause 6.1.2.2.1.1 and inserted in the pFCS field. The PFI field is set to 1. This relationship between the IPv4, IPv6 or OSI network layer PDUs and GFP-F frame is illustrated in Figure 7-7. + +![Diagram showing IPv4/IPv6/OSI network layer PDUs and GFP frame relationships. The Client PDU (IPv4, IPv6, or OSI network layer PDU) is mapped directly into the Payload information field of the GFP frame. The GFP frame header includes PLI, cHEC, Type, tHEC, and a GFP extension header. The pFCS is at the end. Bit and octet alignment is shown at the bottom.](4ff00a489baaa34a0c01070de1d613db_img.jpg) + +| Client PDU | | Octets | GFP frame | | +|------------|-------------------------------------------------|--------|---------------------------|-----------------------------| +| | | 2 | | PLI | +| | | 2 | | cHEC | +| | | 2 | | Type | +| | | 2 | | tHEC | +| | | 0-60 | | GFP extension header | +| Octets | IPv4 PDU, or IPv6 PDU, or OSI network layer PDU | ----- | Payload information field | | +| | | | | | +| | 4 | | | pFCS | +| | 1 2 3 4 5 6 7 8 Bits | | 1 2 3 4 5 6 7 8 Bits | | + +G.7041-Y.13C3(11)\_F7-7 + +Diagram showing IPv4/IPv6/OSI network layer PDUs and GFP frame relationships. The Client PDU (IPv4, IPv6, or OSI network layer PDU) is mapped directly into the Payload information field of the GFP frame. The GFP frame header includes PLI, cHEC, Type, tHEC, and a GFP extension header. The pFCS is at the end. Bit and octet alignment is shown at the bottom. + +**Figure 7-7 – IPv4/IPv6/OSI network layer PDUs and GFP frame relationships** + +## 7.8 DVB ASI payload + +The formats of transport stream (TS) packets are defined in [EN 50083-9] as either 188 bytes or 204 bytes, the latter being referred to as RS-coded TS packets. There is a one-to-one mapping between a TS packet (or a RS-coded TS packet) and a GFP PDU. Specifically, the boundaries of the GFP PDU are aligned with boundaries of the TS packet (or of the RS-coded TS packet). This relationship between TS packets (or RS-coded TS packets) and GFP frames is illustrated in Figure 7-8. + +![Diagram illustrating the relationship between a Transport stream packet (or RS coded transport stream packet) and a GFP frame. The diagram shows the mapping of octets and bits from the TS packet to the GFP frame header and information field.](e151d3468319b81f042ca232c4d82e4b_img.jpg) + +| Transport stream packet
or
RS coded transport stream packet | | Octets | GFP frame | +|-------------------------------------------------------------------|---------------------------------------------------|--------|-----------| +| Octets | 188
TS packet header
+
TS packet payload | 2 | PLI | +| | | 2 | cHEC | +| | | 2 | Type | +| | | 2 | tHEC | +| 16
RS code (optional) | GFP information | | | + +1 2 3 4 5 6 7 8 Bits      1 2 3 4 5 6 7 8 Bits +G.7041-Y.1303(11)\_F7-8 + +Diagram illustrating the relationship between a Transport stream packet (or RS coded transport stream packet) and a GFP frame. The diagram shows the mapping of octets and bits from the TS packet to the GFP frame header and information field. + +Figure 7-8 – TS packet and GFP frame relationships + +### 7.8.1 DVB ASI encapsulation + +The 188 or 204 TS packet octets are placed in the GFP payload information field. Octet alignment is maintained and bit identification within octets is maintained with respect to [ITU-T H.222.0]. Specifically, on an octet-by-octet basis, data bits d7 and d0 (corresponding to 8B information characters H and A) in [EN 50083-9] for a digital video broadcast asynchronous serial interface (DVB ASI) correspond to GFP payload byte bits 1 and 8, respectively. + +### 7.8.2 DVB ASI operations + +#### 7.8.2.1 DVB ASI ingress interface operations + +At the ingress interface, the data bytes and their clock are recovered from the received DVB ASI signal; the processing includes: optical receiver (for fibre-optic-based links) or coupling/impedance matching (for coaxial cable), amplifier/buffer, clock/data recovery and serial-to-parallel conversion, FC comma deletion, 8B/10B decoding, as specified in Annex B of [EN 50083-9]. + +##### 7.8.2.1.1 DVB ASI loss of light + +By reference to FC standards, DVB ASI LOS is an implementation-dependent option. When supported, applicable loss of light (LOL) and signal detect requirements are found in clauses 5.6, 6.2.3.2 and H.10 of [ANSI INCITS 230]. + +##### 7.8.2.1.2 DVB ASI 8B/10B loss of synchronization + +Per Appendix B of [EN 50083-9], DVB ASI codeword synchronization shall be achieved on receipt of two /K28.5/ characters having the same alignment within five consecutive received characters. Enterprise systems connection/single-byte command code sets connection (ESCON/SBCON) character-based codeword loss-of-synchronization criteria should be those specified in clause 7.1 of [ANSI INCITS 296]. + +NOTE – [EN 50083-9] does not specify criteria for declaring loss of codeword synchronization. FC criteria may not be applied since DVB ASI codeword synchronization and transmission is character based, rather than 4-character transmission word based. + +#### **7.8.2.2 TS packet ingress operations** + +The function realizes the synchronization acquisition of the MPEG-2-TS packets or of the RS-coded MPEG-2 TS packets, on the basis of the method proposed in clause 5.2 of [ETSI TR 101 290] (five consecutive correct synchronization bytes for synchronization acquisition; two or more consecutive corrupted synchronization bytes should indicate synchronization loss). + +The packet size (188 bytes or 204 bytes) may be recovered from the received signals on the basis of the periodicity of the synchronization bytes. + +In the case of ingress client failure (either LOS or loss of character synchronization or loss of packet synchronization) it is not possible to delineate any packet; in fact, the impossibility to delineate packets causes the generation of GFP idle frames only. + +GFP-F encapsulation function uses PFI = "0" (no pFCS) and EXI = "0000" (null extension header). + +#### **7.8.2.3 TS packet egress operations** + +At the egress interface, the GFP-F de-encapsulation function removes the core header, de-scrambles the payload area, then passes the TS packet (or the RS-coded TS packet) to the next block also in the case of uncorrectable tHEC assuming the default type conditions. The type of packet (MPEG-2 TS packet or RS-coded MPEG-2 TS packet) is determined on the basis of the length of the received GFP frame. + +In order to recover the TS packet (or RS-coded TS packet) timing information and to remove received packet jitter (due to GFP idle frames, pointer movements, etc.), an end-to-end synchronization method is required. The method to be used is the adaptive clock method described in [ITU-T I.363.1]. + +NOTE – This method is appropriate because it is not necessary in the case of the transport of compressed video programmes to comply with the wander specifications of [b-ITU-T G.823]. Furthermore, the adaptive clock method does not rely on the availability of an external reference clock. End-to-end synchronization of the TS packets (or of the RS-coded TS packets) can be recovered on the basis of arrival time of received GFP frames. + +The transport packet jitter shall meet the jitter requirements specified in [ISO/IEC 13818-9]. + +#### **7.8.2.4 DVB ASI egress interface operations** + +The processing includes 8B/10B coding, FC comma symbols insertion, parallel-to-serial conversion, amplifier buffer and optical emitter (for fibre-optic-based links) or coupling/impedance matching (for coaxial cable), as specified in Annex B of [EN 50083-9]. + +The running disparity (RD) aspects shall adhere to the FC standard, which are found in clause 11 of [ANSI INCITS 230]. + +When the receiving buffer underflows, the egress DVB ASI transmitter should continuously output the 10B neutral disparity codeword, depending on the beginning running disparity (RD- or RD+), following the rules described in clause 8.1.1.1, forcing loss-of-synchronization detection and any associated action at the downstream DVB ASI receiver. + +## **7.9 Transporting Ethernet 10GBASE-R payloads with preamble transparency and ordered set information** + +The mapping of this clause is defined for applications where there is a requirement to preserve the Ethernet frame preamble and ordered set information when the 10GBASE-R signal is carried by GFP-F in addition to the Ethernet frames. This preamble and ordered set information is not defined to be part of the Ethernet frame by [IEEE 802.3], and consequently is not carried by GFP-F in the Ethernet frame-based mapping defined in clause 7.1. + +### 7.9.1 Using 64B/66B information to delimit data and ordered sets + +A 10GBASE LAN signal is made up of several layers: + +![Figure 7-9 – 10GBASE-R LAN model diagram showing layers: MAC, Reconciliation, PCS, PMA, PMD, and 10GBase-R. An XGMII interface is shown between Reconciliation and PCS.](1ab49904e6a60be337d5b75cb7cc8ab7_img.jpg) + +The diagram illustrates the 10GBASE-R LAN model layers. From top to bottom, the layers are: MAC, Reconciliation, PCS, PMA, and PMD. The Reconciliation layer is connected to the PCS layer via an XGMII interface, indicated by an arrow pointing to the interface. The PMD layer is connected to the 10GBase-R physical medium. A reference code G.7041-Y.1303(11)\_F7-9 is shown at the bottom. + +Figure 7-9 – 10GBASE-R LAN model diagram showing layers: MAC, Reconciliation, PCS, PMA, PMD, and 10GBase-R. An XGMII interface is shown between Reconciliation and PCS. + +Figure 7-9 – 10GBASE-R LAN model + +The physical coding sublayer (PCS) is described in clause 49.2 of [IEEE 802.3], including the delimiting of data frames and ordered sets. + +### 7.9.2 GFP-F encapsulation + +As shown in [IEEE 802.3] Figure 46-3, the Ethernet data stream at the XGMII consists of: . For the purposes of these mappings, the client data frames include the information, and the ordered sets include specific information carried in the characters. The mapping of both client data frames and ordered sets into GFP-F frames is described in this clause. Each GFP-F frame uses the core header and type header. The GFP type field is shown in Figure 6-5. The UPI field indicates data or ordered sets. The rest of the fields are static: + +- PTI = 000 (client data) +- PFI = 0 (no FCS) +- EXI = 0000 (null extension header) + +The functional model of the mapping is illustrated in Figure 7-10. EthPP represents the Ethernet PDU with its preamble and EthOS represents the Ethernet ordered set information. Note that there is no Ethernet MAC termination function. Consequently, since no error checking is performed on the Ethernet MAC frames, errored MAC frames are forwarded at both the ingress and egress to the GFP adaptation functions. + +NOTE 1 – Since no MAC function exists at the GFP source or sink, Ethernet auto-negotiation is performed between Ethernet terminals across the GFP link rather than between the Ethernet terminal and the GFP source/sink equipment. + +![Figure 7-10 – Functional model for mapping 10GBASE-R information into the ODUk diagram showing data flow from Client data stream through ETY and ODUk/EthPP/ODUk/EthOS blocks into an OTH network.](63a2519518616620ef0e53d98b923c05_img.jpg) + +The diagram shows the functional model for mapping 10GBASE-R information into the ODUk. On the left, a 'Client data stream' enters an 'ETY' block. Above the 'ETY' block is 'ETH\_CI + preamble' information, which is also input to the 'ETY' block. The 'ETY' block outputs 'ETY ordered set information' and 'ETY\_CI'. The 'ETY ordered set information' is input to an 'ODUk/EthPP' and 'ODUk/EthOS' block. This block outputs to an 'OTH network' (represented by an oval). On the right side, the 'OTH network' outputs to another 'ODUk/EthPP' and 'ODUk/EthOS' block. This block outputs 'ETY ordered set information' and 'ETY\_CI'. The 'ETY ordered set information' is input to an 'ETY' block, which also receives 'ETH\_CI + preamble' information. The 'ETY' block outputs the final 'Client data stream'. A reference code G.7041-Y.1303(11)\_F7-10 is shown at the bottom right. + +Figure 7-10 – Functional model for mapping 10GBASE-R information into the ODUk diagram showing data flow from Client data stream through ETY and ODUk/EthPP/ODUk/EthOS blocks into an OTH network. + +Figure 7-10 – Functional model for mapping 10GBASE-R information into the ODUk + +NOTE 2 – The Ethernet control codes such as idle, error and the reserved codes are not transferred. + +At the egress from the GFP sink adaptation process, the IEEE 802.3 rules shall be observed in the reconstituted Ethernet data stream, including the appropriate insertion of IFG characters. + +#### 7.9.2.1 Client data frame encapsulation + +Unlike the Ethernet frame mapping specified in clause 7.1, this mapping includes the Ethernet frame preamble information in the GFP-F payload area along with the client Ethernet data frame. See Figure 7-11. As specified in clause 46.2 of [IEEE 802.3], the preamble consists of seven octets beginning with the /S/ (start) control character and followed by the start of frame delimiter (SFD) character. Since the /S/ control character is always present at the beginning of the preamble, as shown in Figure 7-11, it is mapped as a fixed value of 0x55 when it is inserted into the GFP-F frame. The SFD character is included, however, to ensure there is no ambiguity regarding the beginning of the client data frame. Specifically, the six preamble octets and the SFD are pre-pended to the Ethernet data frame in their network octet transmission order. Consistent with the Ethernet data mapping into GFP, the bit order of each octet is mapped such that preamble/SFD octet bit 7 corresponds to GFP octet bit 1 and preamble/SFD octet bit 0 corresponds to GFP octet bit 8. + +![Diagram showing the mapping of an Ethernet client data frame and its preamble into a GFP frame. The diagram is split into two columns: 'Ethernet client data frame' on the left and 'GFP frame' on the right. The left column lists fields like /S/, preamble characters, frame start delimiter, Destination address (DA), Source address (SA), Length/type, MAC client data, Pad, and FCS, with their respective octet sizes. The right column shows the GFP frame structure with a Core header (Payload length (PLI), cHEC) and a Type header (Payload type information, tHEC). The /S/ octet is mapped to a fixed 0x55 value. The remaining fields (preamble through FCS) are mapped into the GFP payload area. Bit and octet numbering is indicated at the top of each column.](ddee3e67e0dfc22e25188fa635a19558_img.jpg) + +| Ethernet client data frame | | GFP frame | | +|-----------------------------------|--------------------------|------------------|--------------------------| +| Octets | Bit # | Bit # | Octets | +| 1 2 3 4 5 6 7 8 | | 1 2 3 4 5 6 7 8 | | +| 1 | /S/ | Core header | Payload length (PLI) | +| 6 | preamble characters | | cHEC | +| 1 | frame start delimiter | Type header | Payload type information | +| 6 | Destination address (DA) | | tHEC | +| 6 | Source address (SA) | | 0x55 | +| 2 | Length/type | GFP payload | | +| | MAC client data | | | +| | Pad | | | +| 4 | FCS | | | + +G.7341-Y.1303(11)\_F7-1 + +Diagram showing the mapping of an Ethernet client data frame and its preamble into a GFP frame. The diagram is split into two columns: 'Ethernet client data frame' on the left and 'GFP frame' on the right. The left column lists fields like /S/, preamble characters, frame start delimiter, Destination address (DA), Source address (SA), Length/type, MAC client data, Pad, and FCS, with their respective octet sizes. The right column shows the GFP frame structure with a Core header (Payload length (PLI), cHEC) and a Type header (Payload type information, tHEC). The /S/ octet is mapped to a fixed 0x55 value. The remaining fields (preamble through FCS) are mapped into the GFP payload area. Bit and octet numbering is indicated at the top of each column. + +Figure 7-11 – Ethernet client data frame and preamble mapping into GFP-F + +#### 7.9.2.2 Ordered set encapsulation + +The 10 Gbit Ethernet ordered set is defined in clause 49.2.4 of [IEEE 802.3]. An ordered set consists of four octets, beginning with a special character (/O/) followed by three data octets. Each ordered set is mapped into its own GFP-F frame, as shown in Figure 7-12. The first octet of the ordered set has the four MSBs set to all-zeros and the four LSBs equal to the O code. This way both sequence ordered sets (O code = 0000) and signal ordered sets (O code = 1111) can be transferred. The next three octets contain the three data bytes of the ordered set. The ordered set octets are mapped into the GFP payload area in network octet transmission order. Consistent with the Ethernet data mapping into GFP, the bit order of each octet is mapped such that ordered set octet bit 7 corresponds to GFP octet bit 1 and ordered set octet bit 0 corresponds to GFP octet bit 8. + +During a link fault condition, clause 46.3.4 of [IEEE 802.3] specifies that the fault be signalled by continuously transmitting the appropriate fault status ordered set. The additional bandwidth required + +for the GFP encapsulation prevents all of the ordered sets from being transmitted. However, since the stream of ordered sets is continuous, [IEEE 802.3] allows some of these ordered sets to be discarded as long as some are passed to the Ethernet sink to communicate the link status. The GFP source adaptation process shall encapsulate and transmit these link status ordered sets as bandwidth allows, and discard others. In the same manner as for all ordered sets, the GFP sink adaptation process shall convert the ordered set information it receives in a GFP frame into an ordered set that is transmitted on the 10GBASE-R egress link. + +![Diagram showing the mapping of an Ethernet ordered set into a GFP frame. The Ethernet ordered set (left) consists of an /O/ character in octet 1 and Data in octet 3. The GFP frame (right) consists of a Core header (Payload length (PLI) and cHEC), a Type header (Payload type info. and tHEC), and a GFP payload. The /O/ character maps to a field with '0000' and 'O code', while the Data maps to the GFP payload.](b05bae46f7079e5c9b1da38adb2319e8_img.jpg) + +**GFP frame** + +| Ethernet ordered set | | Bit # | | | | | | | | Octets | +|-----------------------------|-----------------|----------------------|---|---|---|--------|---|---|---|--------| +| Octets | Bit # | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | | +| 1 | 1 2 3 4 5 6 7 8 | Payload length (PLI) | | | | | | | | 2 | +| | | cHEC | | | | | | | | 2 | +| 1 | /O/ | Payload type info. | | | | | | | | 2 | +| 3 | Data | tHEC | | | | | | | | 2 | +| | | 0000 | | | | O code | | | | 4 | +| | | GFP payload | | | | | | | | | + +G.7041-Y.1303(11)\_F7-12 + +Diagram showing the mapping of an Ethernet ordered set into a GFP frame. The Ethernet ordered set (left) consists of an /O/ character in octet 1 and Data in octet 3. The GFP frame (right) consists of a Core header (Payload length (PLI) and cHEC), a Type header (Payload type info. and tHEC), and a GFP payload. The /O/ character maps to a field with '0000' and 'O code', while the Data maps to the GFP payload. + +**Figure 7-12 – Ethernet ordered set mapping into GFP-F** + +#### 7.9.2.3 Fault handling + +There are three types of Ethernet PCS faults that can be detected at the ingress to the GFP source adaptation process: + +- LOS +- loss of codeword synchronization +- high bit error rate + +When any of these conditions is detected, GFP client signal fail frames are sent from the GFP source to the GFP sink as specified in clause 6.3. The consequent action of the 10GBASE-R source at the egress of the GFP sink adaptation function is for further study. + +NOTE – The response to the reception of /E/ error termination characters is not defined. + +## 7.10 Precision time protocol + +The precision time protocol (PTP) uses packets to communicate highly accurate frequency, phase and time-of-day information. PTP messages are encapsulated in GFP-F frames as illustrated in Figure 7-13. The content of the PTP common message header and message fields are specified in [ITU-T G.8275.1]. The types of PTP messages used for a given application are defined in the Recommendation associated with that application. + +![Figure 7-13: PTP message mapping into GFP-F. This diagram shows the mapping of a PTP frame into a GFP frame. The PTP frame consists of a 34-octet 'PTP common message header' and 'm' octets of 'PTP message fields'. The GFP frame structure includes a 2-octet 'PLI', 2-octet 'cHEC', 2-octet 'Type', 2-octet 'tHEC', a 'GFP payload' (which carries the PTP frame), and a 4-octet 'pFCS'. Bit positions 1-8 are indicated for both frames.](e8e818455bb0d1a6153299a388b94868_img.jpg) + +PTP frame + +GFP frame + +Octets + +2 PLI + +2 cHEC + +2 Type + +2 tHEC + +34 PTP common message header + +m PTP message fields + +GFP payload + +4 pFCS + +1 2 3 4 5 6 7 8 Bits + +1 2 3 4 5 6 7 8 Bits + +G.7041-Y.1303(16)\_F7-13 + +Figure 7-13: PTP message mapping into GFP-F. This diagram shows the mapping of a PTP frame into a GFP frame. The PTP frame consists of a 34-octet 'PTP common message header' and 'm' octets of 'PTP message fields'. The GFP frame structure includes a 2-octet 'PLI', 2-octet 'cHEC', 2-octet 'Type', 2-octet 'tHEC', a 'GFP payload' (which carries the PTP frame), and a 4-octet 'pFCS'. Bit positions 1-8 are indicated for both frames. + +Figure 7-13 – PTP message mapping into GFP-F + +## 7.11 Synchronization status messages + +A synchronization status message (SSM) provides information regarding the quality of the clock source being used by the SSM source. + +An SSM is encapsulated in GFP-F frames as illustrated in Figure 7-14. The contents of the SSM are specified in [ITU-T G.781]. The basic SSM is a single octet message, using only the first octet of the SSM message field shown in Figure 7-14. + +![Figure 7-14: SSM mapping into GFP-F. This diagram shows the mapping of an SSM frame into a GFP frame. The SSM frame structure includes a 1-octet 'SSM message' (with bits 0-7), a 'Reserved' octet, an 'Extended QL TLV, including the extended SSM message' (0 or 20 octets), and 'Reserved' octets (0 - n). The GFP frame structure is identical to Figure 7-13, with the SSM frame as the 'GFP payload'. Bit positions 1-8 are indicated for both frames.](67d03c9e89620d73e3786c869e559752_img.jpg) + +SSM frame + +GFP frame + +Octets + +2 PLI + +2 cHEC + +2 Type + +2 tHEC + +1 SSM message Reserved + +0 or 20 Extended QL TLV, including the extended SSM message + +0 - n Reserved + +GFP payload + +4 pFCS + +1 2 3 4 5 6 7 8 Bits + +1 2 3 4 5 6 7 8 Bits + +G.7041-Y.1303(16)\_F7-14 + +Figure 7-14: SSM mapping into GFP-F. This diagram shows the mapping of an SSM frame into a GFP frame. The SSM frame structure includes a 1-octet 'SSM message' (with bits 0-7), a 'Reserved' octet, an 'Extended QL TLV, including the extended SSM message' (0 or 20 octets), and 'Reserved' octets (0 - n). The GFP frame structure is identical to Figure 7-13, with the SSM frame as the 'GFP payload'. Bit positions 1-8 are indicated for both frames. + +Figure 7-14 – SSM mapping into GFP-F + +In order to support enhanced clocks and new functionality, an extended SSM is defined in Figure 7-14. The contents of the extended SSM are defined in clause 11.3.1.3 of [ITU-T G.8264]. The Extended SSM includes the 20-byte field after the SSM octet, and may optionally include other TLVs as they are defined in the future. Consistent with [ITU-T G.8264] and [IEEE 802.3], on an octet-by-octet bases, bits 0 and 7 of the extended SSM correspond to bits 8 and 1 in the GFP frame. + +# 8 Payload-specific aspects for transparent mapping of 8B/10B clients into GFP + +Transparent mapping of 8B/10B payloads into GFP is intended to facilitate the transport of 8B/10B block-coded client signals for scenarios that require very low transmission latency. Examples of such client signals include FC, ESCON, fibre connection (FICON) and gigabit Ethernet. Rather than buffering an entire frame of the client data into its own GFP frame, the individual characters of the client signal are demapped from the client block codes and then mapped into periodic, fixed-length GFP frames. The mapping occurs regardless of whether the client character is a data or a control character, which thus preserves the client 8B/10B control codes. Frame multiplexing is not precluded with transparent GFP. + +NOTE – Throughout this clause, the term "ESCON" is used to refer to both the ESCON and SCON client signals. + +## 8.1 Common aspects of GFP-T + +The transparent GFP frame uses the same frame structure as the frame-mapped GFP, including the required payload header. The pFCS is optional. The transparent GFP frame format is depicted in Figure 8-1. + +![Diagram of Transparent GFP frame format showing Core header and Payload area structures.](b44f89b176c971c7dd264c07bfef2c2a_img.jpg) + +The diagram illustrates the structure of a Transparent GFP frame. It is divided into two main sections: the Core header and the Payload area. + +- Core header:** Consists of two fields: "16-bit payload length indicator" and "cHEC (CRC-16)". +- Payload area:** Contains the following fields: + - Payload header:** 4-64 bytes. + - Payload information field:** Calculated as $[N \times ((8 \times 65B) + 16)]$ . + - Optional payload FCS:** CRC-32. + +On the right side, a detailed view of the payload structure is shown, which includes: + +- 16-bit payload type field +- tHEC (CRC-16) +- Extension header (0-58 bytes) – marked as **Optional** +- eHEC (CRC-16) – marked as **Optional** + +Source: G.7041-Y.1303(11)\_F8-1 + +Diagram of Transparent GFP frame format showing Core header and Payload area structures. + +Figure 8-1 – Transparent GFP frame format + +### 8.1.1 Adapting 8B/10B client signals via 64B/65B block codes + +As depicted in the functional model in Figure 2, the first step in the client adaptation process is to decode the physical layer of the client signal. For 8B/10B line codes, the received 10-bit character is decoded into its original 8-bit value, if it is an 8B/10B data codeword, or into a control character if it is an 8B/10B control codeword. The 8B/10B control codewords are mapped into one of the 16 possible 4-bit control code indicators for the 8-bit control characters available in transparent GFP (see Table 8-1). + +**Table 8-1 – Mapping between 8B/10B control characters +and the 64B/65B control code indicators** + +| Name | Octet value | 10B codeword (RD–)
abcdei fghj | 10B codeword (RD+)
abcdei fghj | 64B/65B
4-bit mapping | +|---------|-------------|-----------------------------------|-----------------------------------|--------------------------| +| /K28.0/ | 1C | 001111 0100 | 110000 1011 | 0000 | +| /K28.1/ | 3C | 001111 1001 | 110000 0110 | 0001 | +| /K28.2/ | 5C | 001111 0101 | 110000 1010 | 0010 | +| /K28.3/ | 7C | 001111 0011 | 110000 1100 | 0011 | +| /K28.4/ | 9C | 001111 0010 | 110000 1101 | 0100 | +| /K28.5/ | BC | 001111 1010 | 110000 0101 | 0101 | +| /K28.6/ | DC | 001111 0110 | 110000 1001 | 0110 | +| /K28.7/ | FC | 001111 1000 | 110000 0111 | 0111 | +| /K23.7/ | F7 | 111010 1000 | 000101 0111 | 1000 | +| /K27.7/ | FB | 110110 1000 | 001001 0111 | 1001 | +| /K29.7/ | FD | 101110 1000 | 010001 0111 | 1010 | +| /K30.7/ | FE | 011110 1000 | 100001 0111 | 1011 | +| 10B_ERR | 01 | Unrecognized RD– | Unrecognized RD+ | 1100 | +| 65B_PAD | 02 | N/A | N/A | 1101 | +| Spare | 03 | N/A | N/A | 1110 | +| Spare | 04 | N/A | N/A | 1111 | + +NOTE 1 – While all 256 data characters must be supported, only 12 special 8B/10B control codewords are recognized and used for 64B/65B control characters in gigabit Ethernet, FC, FICON and ESCON. Hence, the compression of special 8B/10B control codewords into 4-bit values is possible without restricting client signals, or providing protocol-specific handling of 8B/10B control codewords. + +NOTE 2 – The re-coding process is entirely unaware of the meaning of control words or ordered sets. It simply generically recodes data and control words into 65B blocks. No knowledge of start-of-frame, end-of-frame, errors, idles, control codes, ordered sets, etc., is required. + +The decoded 8B/10B characters are then mapped into a 64B/65B block code. The structure of the 64B/65B block code is shown in Figure 8-2. The leading bit of the 65-bit block, the flag bit, indicates whether that block contains only 64B/65B 8-bit data characters or whether client control characters are also present in that block (flag bit = 0 indicates data octets only and flag bit = 1 indicates at least one control octet in the block). Client control characters, which are mapped into 8-bit 64B/65B control characters, are located at the beginning of the 64-bit block payload if they are present in that block. The first bit of the 64B/65B control character contains a last control character (LCC) flag bit which indicates whether this control character is the last one in this block (LCC = 0), or whether there is another control character in the next octet (LCC = 1). The next three bits contain the control code locator, which indicates the original location of the 8B/10B control code character within sequence of the eight client characters contained in the block. The last 4 bits, the control code indicator, give the 4-bit representation of the 8B/10B control code character. The explicit mapping of 8B/10B control code characters into the 4-bit control codes is defined in Table 8-1. The control codes are mapped into the payload bytes of the 64B/65B code in the order in which they were received. Note that, as a result, the control code addresses aaa-hhh in Figure 8-2 will be in ascending order. + +| Input client characters | Flag bit | 64-bit (8-octet) field | | | | | | | | +|-------------------------|----------|------------------------|-------------|-------------|-------------|-------------|-------------|-------------|-------------| +| | | D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8 | +| All data | 0 | D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8 | +| 7 data, 1 control | 1 | 0 aaa
C1 | D1 | D2 | D3 | D4 | D5 | D6 | D7 | +| 6 data, 2 control | 1 | 1 aaa
C1 | 0 bbb
C2 | D1 | D2 | D3 | D4 | D5 | D6 | +| 5 data, 3 control | 1 | 1 aaa
C1 | 1 bbb
C2 | 0 ccc
C3 | D1 | D2 | D3 | D4 | D5 | +| 4 data, 4 control | 1 | 1 aaa
C1 | 1 bbb
C2 | 1 ccc
C3 | 0 ddd
C4 | D1 | D2 | D3 | D4 | +| 3 data, 5 control | 1 | 1 aaa
C1 | 1 bbb
C2 | 1 ccc
C3 | 1 ddd
C4 | 0 eee
C5 | D1 | D2 | D3 | +| 2 data, 6 control | 1 | 1 aaa
C1 | 1 bbb
C2 | 1 ccc
C3 | 1 ddd
C4 | 1 eee
C5 | 0 fff
C6 | D1 | D2 | +| 1 data, 7 control | 1 | 1 aaa
C1 | 1 bbb
C2 | 1 ccc
C3 | 1 ddd
C4 | 1 eee
C5 | 1 fff
C6 | 0 ggg
C7 | D1 | +| 8 control | 1 | 1 aaa
C1 | 1 bbb
C2 | 1 ccc
C3 | 1 ddd
C4 | 1 eee
C5 | 1 fff
C6 | 1 ggg
C7 | 0 hhh
C8 | + +- Leading bit in a control octet (LCC) = 1 if there are more control octets and = 0 if this payload octet contains the last control octet in that block. +- aaa = 3-bit representation of the first control code's original position (first control code locator). +- bbb = 3-bit representation of the second control code's original position (second control code locator). +- ... +- hhh = 3-bit representation of the eighth control code's original position (eighth control code locator). +- Ci = 4-bit representation of the i-th control code (control code indicator). +- Di = 8-bit representation of the i-th data value in order of transmission. + +**Figure 8-2 – Transparent GFP 64B/65B code components +(see Figure 8-3 for actual superblock structure)** + +For example, if there is a single 64B/65B control character in a block, and it was originally located between 8B/10B data codewords D2 and D3, the first octet of the 64B/65B block will contain 0.010.C1. The LCC value of 0 indicates that this 64B/65B control character is the last one in that block and the value of aaa = 010 indicates C1's location between D2 and D3. At the demapper, the 64B/65B data characters are remapped as 8-bit data octets and then encoded back into the 8B/10B data codewords. For 64B/65B control characters, the four-bit control code indicators are remapped into the appropriate 8B/10B control codewords with their positions within the original character stream restored based on the three-bit control code locator. + +#### 8.1.1.1 10B\_ERR code + +Certain client signal defects may produce 8B/10B codewords on ingress to the GFP source adaptation process that cannot be recognized by the 64B/65B adaptation process (e.g., a CSF, an illegal 8/10B codeword or a legal codeword with an RD error, see clause 8.2). A special 64B/65B control character, the 10B\_ERR code, is provided to convey such "unrecognized 8B/10B codeword" client signal defects. + +When reconstructing the client signal on egress from the transport network, it is recommended that received 10B\_ERR codes be typically recoded by the demapper into an invalid transmission character of either 001111 0001 (RD–) or 110000 1110 (RD+) (fixed, illegal 8B/10B codewords with neutral disparity, containing a transition within both the first three bits and last three bits of the codeword), depending on RD (see clause 8.2.3 for other client-specific RD considerations). Although the actual value of the unrecognized 8B/10B codeword is not retained, the occurrence and location of the client signal defect are preserved. + +In addition to the recommended invalid transmission character (whose construction minimizes the possible creation of aliased commas when combined with adjacent characters), 10B\_ERR events may also be demapped into alternate invalid transmission characters, provided that these alternate invalid transmission characters also meet all 8B/10B coding rules, are of neutral disparity and contain a minimum of one transition within both the first four bits and last four bits of the codeword. + +#### 8.1.1.2 Insertion of 65B\_PAD code and GFP client management frames + +Since the transparent GFP application requires that the available path (channel) capacity is at least that of the client signal base (pre-encoding) data rate, the input receive (ingress) buffer at the mapper will regularly approach underflow. For rate adaptation purposes, if a transparent GFP frame is currently being transmitted and if there are no client characters ready for transmission by the transparent GFP mapper, the mapper shall insert a 65B\_PAD padding character. The pad character is mapped into the GFP frame in the same manner as a control character and is recognized and removed by the GFP demapper. Client-specific considerations for 65B\_PAD code handling are given in clause 8.4.1. + +Client data frames are transmitted with priority over CMFs. If a GFP CMF is available to transmit, and the ingress buffer is nearly empty (e.g., if a 65B\_PAD character has been sent during the current client data frame), then the CMF may be sent after the current client data frame. In order to maintain low latency, it is recommended that, for a right-sized channel, only a single CMF be sent between client data frames. It is also recommended that CMFs used with transparent GFP be limited to a payload information field of eight bytes or less. Note that low latency may also be maintained by increasing the channel size to allow the exchange of additional CMFs. + +### 8.1.2 Adapting 64B/65B code blocks into GFP + +To preserve the octet alignment of the transparent GFP signal with the transport SDH/ODUk frame, the first step in the adaptation process is to group eight 64B/65B codes into a superblock as shown in Figure 8-3. The leading (flag) bits of each of the eight 64B/65B codes are grouped together into a first trailing octet. The 16 bits of the last two trailing octets are used for a CRC-16 error check over the bits of this superblock. + +| | | | | | | | | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|--------|--------|--------|--------|--------|--------| +| Octet 1, 1 | | | | | | | | +| Octet 1, 2 | | | | | | | | +| Octet 1, 3 | | | | | | | | +| ⋮ | | | | | | | | +| Octet 8, 7 | | | | | | | | +| Octet 8, 8 | | | | | | | | +| L1 | L2 | L3 | L4 | L5 | L6 | L7 | L8 | +| CRC-1 | CRC-2 | CRC-3 | CRC-4 | CRC-5 | CRC-6 | CRC-7 | CRC-8 | +| CRC-9 | CRC-10 | CRC-11 | CRC-12 | CRC-13 | CRC-14 | CRC-15 | CRC-16 | +| where: Octet j, k is the k -th octet of the j -th 64B/65B code in the superblock
Lj is the leading (flag) bit j -th 64B/65B code in the superblock
CRC- i is the i -th error control bit where CRC-1 is the MSB of the CRC | | | | | | | | + +**Figure 8-3 – Superblock structure for mapping 64B/65B code components into the GFP frame** + +NOTE – To minimize latency, the transparent GFP mapper can begin transmitting data as soon as the first 64B/65B code in the group has been formed rather than waiting for the entire superblock to be formed. + +Assuming no pFCS and a null extension header, the resulting GFP frame is $\{N \times [(65 \times 8) + 16] + (8 \times 8)\}$ bits long, where *N* is the number of superblocks in the GFP frame. The value of *N* depends + +on the base, uncoded rate of the client signal and on the transport channel capacity. Suggested SDH virtually concatenated channel capacities and the associated minimum values for $N$ are shown in Appendix IV. Suggested channel capacities for other transport paths are for further study. The minimum value of $N$ depends on the data rate of the client signal, the number of GFP frame overhead octets (e.g., 8 with no optional pFCS and a null extension header), and the size of the payload envelope, as shown in Appendix IV. Specifically, $N_{\min}$ must be chosen such that for the fastest tolerance client clock rate and slowest tolerance SDH/OTN clock rate, the time required to transmit the GFP frame containing the $N \times 8 \times 8$ client characters is less than the time in which the client can deliver these $N \times 8 \times 8$ characters to the GFP mapper. + +Note that $N$ may be optionally configurable according to SBW requirements for the transport of CMFs (see Appendix IV). + +#### 8.1.2.1 Error control with transparent GFP + +The 16-error control bits in a superblock (see Figure 8-3) contain a CRC-16 error check code over the 536 bits in that superblock. If the demapper detects an error, it should output either 10B error characters or unrecognized 10B characters in place of all of the client characters contained in that superblock. The 10B error and unrecognized characters are described for disparity errors in the client-specific aspects (see clause 8.2). This replacement guarantees that the client receiver will be able to detect the presence of the error. + +The generator polynomial for the CRC-16 is $G(x) = x^{16} + x^{15} + x^{12} + x^{10} + x^4 + x^3 + x^2 + x + 1$ with an initialization value of zero, where $x^{16}$ corresponds to the MSB and $x^0$ to the LSB. The superblock CRC is generated by the source adaptation process using the following steps: + +- 1) the first 65 octets of the superblock are taken in network octet order (see Figure 8-3), MSB first, to form a 520-bit pattern representing the coefficients of a polynomial $M(x)$ of degree 519; +- 2) $M(x)$ is multiplied by $x^{16}$ and divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ of degree 15 or less; +- 3) The coefficients of $R(x)$ are considered to be a 16-bit sequence, where $x^{15}$ is the MSB; +- 4) This 16-bit sequence is the CRC-16. + +NOTE – Single error correction is also possible with this CRC-16. However, since the sink adaptation process performs the CRC-16 check after the payload descrambling is performed, the error correction circuit should account for single bit errors, as well as double errors spaced 43 bits apart coming out of the descrambler. + +The sink adaptation process performs steps 1)–3) in the same manner as the source adaptation process, except that here, the $M(x)$ polynomial of step 1 includes the CRC-16 bits in received order, and has degree 535. In the absence of bit errors, the remainder shall be 0000 0000 0000 0000. + +## 8.2 Running disparity in 64B/65B codes + +8B/10B codewords are designed to facilitate error-free transmission by maintaining DC balance, providing significant transitions for clock recovery and limiting run-length of consecutive 1s or 0s. DC balance is measured on a codeword-by-codeword basis by keeping track of RD. RD is either positive (indicating more 1s than 0s have been sent), or negative (more 0s than 1s sent). + +In order to maintain DC balance in 8B/10B codewords, each 8-bit data character and each of the 12 recognized "special control characters" have two 10-bit encodings. Depending on current RD, the 8B/10B encoder will select which of the two encodings to transmit for next data or control character in order to either flip the RD, or to maintain the current RD. Specifically, the new codeword flips the RD from negative to positive if there have been more 0s than 1s transmitted, from positive to negative if there have been more 1s than 0s transmitted or maintains the RD if there has been an equal number of 1s and 0s. + +Transmission bit errors may cause a received 8B/10B codeword to have the wrong disparity for the current beginning RD state. In these cases, an RD error is detected. Independent of the received character's validity, the received transmission character shall be used to calculate a new value of RD. The new value shall be used as the receiver's current RD for the next received transmission character. + +NOTE – Transmission bit errors may also result in the errored codeword being received with correct disparity and a corrupted but legal 8B/10B codeword that results in some later non-errored codeword being detected with an RD error. In some cases, protocol-specific RD rules have been created to ensure each data packet begins or ends with defined disparity so that errors will not be propagated across data packets. + +### **8.2.1 Handling of running disparity on ingress** + +On ingress, the initial RD, upon power-on, reset or transition from an LOS or loss of codeword synchronization phase, may be assumed to be either positive or negative. + +A match to the received 10B character is searched for in the appropriate RD+ or RD– column of the 8B/10B valid codeword lookup table, depending on the current beginning RD. If no match is found, either an illegal codeword or a legal codeword with a RD error has been detected. Both are treated as 8B/10B code violations, and are replaced with the 10B\_ERR code in the 64B/65B mapping process. + +### **8.2.2 Handling of running disparity on egress** + +On egress, the initial RD upon power-on, reset or transition from an LOS or loss of codeword synchronization phase shall be assumed to be negative. + +Transparent transport implementations must generate correct RDs using any applicable protocol-specific rules. References are provided in clause 8.2.3 to the standard(s) that define each currently applicable protocol's disparity rules. + +10B\_ERR codes are recoded into client signals either as an unrecognized codeword with valid RD or as a protocol-specific error, depending on the protocol, as described in clause 8.2.3. + +### **8.2.3 Client-specific running disparity aspects** + +This clause describes the client-specific RD rules for each of the identified, supported 8B/10B client protocols. + +#### **8.2.3.1 Fibre channel payload** + +RD rules for a FC are found in clause 11 of [ANSI INCITS 230]. In addition to the "generic" RD rules specified in clause 11.2 of [ANSI INCITS 230] FC-specific rules in clause 11.4 of [ANSI INCITS 230] provide two versions of each end of frame (EOF) ordered set, and dictate their use to ensure that a negative RD will result after processing of the final character of the EOF ordered set. Ordered sets defined for the primitive signals and primitive sequences preserve this negative disparity, ensuring that the ordered sets associated with start of frame (SOF) delimiters (SFDs), primitive signals and primitive sequences will also always be transmitted with a negative beginning RD. This restriction allows FC idle words to be removed and added from an encoded bit stream one word at a time without altering the beginning RD. + +To prevent subsequent valid FC frames from being declared invalid, the K28.5 character associated with all ordered sets except EOF should be generated assuming a beginning negative RD. In the event that a previous transmission error results in an incorrect EOF for the current RD, the next ordered set will be generated with RD– K28.5, forcing the ending RD to be negative. As a result, transmission errors will not cause a RD error to be propagated across frames. + +For "transparent transport" of FC payloads, 10B\_ERR shall be recoded into an unrecognized 10B neutral disparity codeword, depending on the beginning running disparity (RD– or RD+), following the rules described in clause 8.1.1.1. + +#### 8.2.3.2 ESCON payload + +RD rules for ESCON are found in clause 6.2.2 of [ANSI INCITS 296]. Since ESCON does not define an error code to substitute for code violations, on egress, 10B\_ERR shall be recoded into an unrecognized 10B neutral disparity codeword, depending on the beginning running disparity (RD- or RD+), following the rules described in clause 8.1.1.1. + +#### 8.2.3.3 FICON payload + +For purposes of mapping into transparent GFP, the RD rules for FICON are identical to those specified for FC in [ANSI INCITS 230]. + +#### 8.2.3.4 Gigabit Ethernet payload + +RD rules for gigabit Ethernet are found in clause 36.2.4 of [IEEE 802.3]. Two idle encodings are provided, indicated as /I1/ and /I2/. The first /I/ following a packet or configuration ordered set restores the current RD to a negative value. All subsequent /I/s are /I2/ to ensure a negative ending RD. This restriction allows single /I2/s to be inserted/removed for rate adaptation without altering the beginning RD associated with the code-group subsequent to the inserted or removed /I2/. + +In order to ensure beginning negative RD for each SOF, all /I2/ idles should be generated with RD-K28.5, ensuring a beginning negative RD for the next idle or SOF. + +As per clause 36.2.4.16 of [IEEE 802.3], RD errors detected on ingress (and replaced with 10B\_ERR codeword in 64B/65B encoding process) should be replaced with /V/ codeword (K30.7) having correct disparity on egress. As an option, it is also permissible to recode received 10B\_ERR into one of the following unrecognized 10B neutral disparity codewords, depending on beginning running disparity: 001111 0001 (RD-) or 110000 1110 (RD+). As an option, it is also permissible to recode received 10B\_ERR into an unrecognized 10B neutral disparity codeword, depending on the beginning running disparity (RD- or RD+), following the rules described in clause 8.1.1.1. + +It should be noted that such optional introduction of demapped 10B\_ERR codes into the data stream is only appropriate when the attached Ethernet system is not using error logging for system maintenance support. + +NOTE – In [ITU-T G.709], two replacement signals are defined for GbE: + +- the failed GbE signal is replaced by a stream of 10B blocks, with a bit rate of $1\,250\,000\text{ kbit/s} \pm 100\text{ ppm}$ , each carrying a link fault indication as specified in [IEEE 802.3] (applicable at ingress and egress side), or +- the GFP-T signal is replaced by a stream of GFP client signal fail (CSF) and GFP-idle frames with a bit rate of $15/16 \times 1\,250\,000\text{ kbit/s} \pm 100\text{ ppm}$ (applicable at the ingress side only). + +#### 8.2.3.5 DVB ASI payload + +The RD aspects of the DVB ASI mapping in GFP shall adhere to the FC standard, which are found in clause 11 of [ANSI INCITS 230]. On egress, 10B\_ERR shall be recoded into an unrecognized 10B neutral disparity codeword, depending on the beginning running disparity (RD- or RD+), following the rules described in clause 8.1.1.1. + +## 8.3 Client-specific signal fail aspects + +When transparent GFP mapping detects a CSF at ingress, it may send a "client signal fail" indication as described in clause 6.3.3. Client signal fail conditions include, as a minimum, loss of 8B/10B synchronization and, in some cases, LOS. Other implementation-dependent indications of a failed client signal (e.g., loss-of-clock from an interface between integrated circuits) may be encoded as client signal fail. + +Since client signals are provided as a continuous serial stream of 10-bit characters, it is necessary to find codeword alignment. Special characters containing the "comma" delimiter provide the + +information necessary to achieve and maintain codeword alignment. While all 8B/10B client signals employ the same bit alignment technique, conditions for detecting and clearing loss of 8B/10B synchronization are protocol-specific, and are identified in the following protocol-specific clauses. + +Server layer failures in the GFP process itself, in the 64B/65B adaptation process or in the transport network, may induce a CSF indication to the client adaptation process. + +If the onset of CSF occurs within a GFP client data frame, the remainder of the 64B/65B blocks of that GFP frame shall be filled with 10B\_ERR codes. At the far-end, these shall be decoded as errors. + +At the far-end of a transport network, transparently transported client signals must still be reconstructed and output in a manner that is compliant with the physical and coding interface requirements specific to each protocol. The following client-specific clauses define what action should be taken at client signal egress in response to a received far-end client signal fail indication, or any adaptation or transport defects that make it impossible to extract a client signal. + +### **8.3.1 Fibre channel payload** + +#### **8.3.1.1 Fibre channel loss of light** + +FC LOS is an implementation-dependent option. When supported, applicable LOL and signal detect requirements are found in clauses 5.6, 6.2.3.2 and H.10 of [ANSI INCITS 230]. + +Other implementation-dependent indications of a failed client signal (e.g., loss-of-clock from a SerDes) may be encoded as client signal fail. + +#### **8.3.1.2 Fibre channel 8B/10B loss of synchronization** + +FC conditions for declaring in/out of 8B/10B codeword synchronization are specified in clause 12.1 of [ANSI INCITS 230]. + +#### **8.3.1.3 Fibre channel output due to ingress or transport signal fail** + +Since the goal of transparent GFP mapping is to transport client signals as transparently as possible, it is not appropriate to initiate link initialization or link recovery procedures on egress due to client signal fail or transport failures. It is recommended that the egress FC transmitter generate the Not\_Operational primitive sequence per clause 16.4.2 of [ANSI INCITS 230]. + +NOTE – Older equipment was allowed to continuously output the neutral disparity decoding for 10B\_ERR, forcing loss-of-synchronization detection and the associated action at the downstream FC receiver. + +If the CSF condition persists, the client adaptation process may transmit nothing, forcing LOS detection and associated action at the downstream FC receiver. + +### **8.3.2 ESCON payload** + +#### **8.3.2.1 ESCON loss of signal** + +Optical LOS detection requirements are specified in clauses 5.2 and 5.3 of [ANSI INCITS 296], respectively. + +#### **8.3.2.2 ESCON 8B/10B loss of synchronization** + +ESCON conditions for declaring being in or out of 8B/10B codeword synchronization are specified in clause 7.1 of [ANSI INCITS 296]. + +#### **8.3.2.3 ESCON output due to ingress or transport signal fail** + +Since the goal of transparent GFP mapping is to transport client signals as transparently as possible, it is not appropriate to initiate link initialization or link recovery procedures on egress due to client signal fail or transport failures. It is recommended that the egress ESCON transmitter generate the not-operational sequence per clause 7.4.2 of [ANSI INCITS 296]. + +NOTE – Older equipment was allowed to continuously output the neutral disparity decoding for 10B\_ERR, forcing loss-of-synchronization detection and the associated action at the downstream ESCON receiver. + +If the CSF condition persists, the client adaptation process may transmit nothing, forcing LOS detection and associated action at the downstream ESCON receiver. + +### 8.3.3 FICON payload + +The CSF handling requirements for FICON are identical to those for FC, as specified in [ANSI INCITS 230]. + +### 8.3.4 Full-duplex gigabit Ethernet payload + +#### 8.3.4.1 Gigabit Ethernet loss of signal + +Gigabit Ethernet physical media dependent (PMD) signal detect requirements are specified in clauses 38.2.4 and 39.2.3 of [IEEE 802.3] for fibre and copper interfaces, respectively. + +#### 8.3.4.2 Gigabit Ethernet 8B/10B loss of synchronization + +Gigabit Ethernet conditions for declaring being in or out of 8B/10B codeword synchronization are specified in clause 36.2.5.2.6 and Figure 36-9 of [IEEE 802.3]. + +#### 8.3.4.3 Gigabit Ethernet output due to ingress or transport signal fail + +Since the goal of transparent GFP mapping is to transport client signals as transparently as possible, it is not appropriate to initiate link initialization or link recovery procedures on egress due to client signal fail or transport failures. It is recommended that the egress GbE transmitter continuously output the /V/ ordered set per clause 36.2.4.16 of [IEEE 802.3]. + +If the CSF condition persists, the client adaptation process may transmit nothing, forcing LOS detection and associated action at the downstream GbE receiver. + +NOTE – In [ITU-T G.709], two replacement signals are defined for GbE: + +- the failed GbE signal is replaced by a stream of 10B blocks, with a bit rate of $1\,250\,000\text{ kbit/s} \pm 100\text{ ppm}$ , each carrying a link fault indication as specified in [IEEE 802.3] (applicable at ingress and egress side); or +- the GFP-T signal is replaced by a stream of GFP client signal fail (CSF) and GFP-idle frames with a bit rate of $(15/16) \times 1\,250\,000\text{ kbit/s} \pm 100\text{ ppm}$ (applicable at the ingress side only). + +### 8.3.5 DVB ASI payload + +#### 8.3.5.1 DVB ASI loss of light + +By reference to FC standards, DVB ASI LOS is an implementation-dependent option. When supported, applicable LOL and signal detect requirements are found in clauses 5.6, 6.2.3.2 and H.10 of [ANSI INCITS 230]. + +Other implementation-dependent indications of a failed client signal (e.g., loss-of-clock from a SerDes) may be encoded as client signal fail. + +#### 8.3.5.2 DVB ASI 8B/10B loss of synchronization + +As per Appendix B of [EN 50083-9], DVB ASI codeword synchronization shall be achieved on receipt of two /K28.5/ characters having the same alignment within five consecutive received characters. [EN 50083-9] does not specify criteria for declaring loss of codeword synchronization. FC criteria may not be applied since DVB ASI codeword synchronization and transmission are character based, rather than 4-character transmission word based. In the absence of guidance from [EN 50083-9], ESCON/SBCON character-based codeword loss-of-synchronization criteria should be those specified in clause 7.1 of [ANSI INCITS 296]. + +#### **8.3.5.3 DVB ASI output due to ingress or transport signal fail** + +The egress DVB ASI transmitter should continuously output the neutral disparity decoding for 10B\_ERR, forcing loss-of-synchronization detection and any associated action at the downstream DVB ASI receiver. If the CSF condition persists, the client adaptation process may transmit nothing, forcing LOS detection and associated action at the downstream DVB ASI receiver. + +## **8.4 Synchronous full-rate transparent mapping of 8B/10B clients into GFP** + +Transparent mapping of 8B/10B block-coded clients can be accomplished via a synchronous (full-rate) mapping of all received client characters. This transparent mapping utilizes common character-based mapping described in clause 8.1 as well as client-specific processes described in clauses 8.2.3 and 8.3. In addition, client-specific requirements described in the following clauses are applied before mapping and encapsulating (in the ingress direction) and after de-mapping, extracting 64B/65B blocks and decoding them into 8B/10B block codes (in the egress direction). + +### **8.4.1 Rate adaptation in 64B/65B codes** + +On ingress, rate adaptation to the output payload data rate occurs in the 64B/65B encoding process. If there is not an 8B/10B codeword available for the mapper to recode into 64B/65B block code, the mapper inserts a 65B\_PAD as described in clause 8.1.1.2. Essentially, this 65B\_PAD is a non-client-idle that is used to pad 64/65B blocks for rate adaptation purposes. On egress, the demapper removes these non-client-idle signals. Since fixed-length GFP frames are used, and frames may be padded with 65B\_PADs for rate adaptation, there is no need to buffer an entire GFP frame prior to inserting it into the payload of the outgoing transport signal, thus reducing buffering and delay in the mapping process. + +#### **8.4.1.1 Egress rate adaptation procedures** + +There are two approaches for generating the client egress data interface clock at the GFP client-specific sink-adaptation process. One approach is to adapt the client signal to a clock source that is local to the GFP sink adaptation process. The other approach is to generate the client signal egress clock by deriving it from the received GFP signal and transport clock. + +Should a failure occur in either the ingress client signal or during SDH/OTN transport, a protocol-specific local reference clock is still required at the client data egress point if the client expects a client rate link failure signal to replace the failed client. + +##### **8.4.1.1.1 Rate adaptation to a local reference clock** + +The currently supported 8B/10B client signals specify operating frequencies with clock-offset requirements of $\pm 100$ ppm to $\pm 200$ ppm, which are significantly relaxed compared to SDH or OTN. Each of these client signals is designed to allow rate adaptation to a local reference clock, either at repeaters or at the far-end, through client idle (or fill-word) insertion or removal. To facilitate this rate adaptation, each of these client signals impose minimum IPG rules, which specify the minimum number of idle codewords that must be inserted between data packets. Each of these client signals also specifies the maximum data packet size. Minimum IPG rules have been established to ensure that where rate adaptation to a local clock is required, even under the worst-case condition where a fast input clock and slow output clock require some IPG idles to be deleted, a sufficient IPG will remain between packets for successful client frame delineation. + +This scheme may be employed equally well when reconstructing transparent-mapped client data on egress. With this approach, a local reference clock is supplied at the GFP sink adaptation process. As client data is demapped from GFP frames and recoded into 8B/10B codewords, it is rate adapted to the local reference clock through idle insertion/removal. Client-specific processing is required to recognize legal opportunities to insert/remove idle codewords, generate proper idle codes and insert such codes in the egress bit stream. An example of a client-specific parameter is the minimum and maximum number of idles that are allowed to be inserted or removed. + +Even in links containing multiple repeaters, if all "local" clocks meet the accuracy requirements for the specific protocol, sufficient opportunities for idle insertion or removal will occur, since aggregate timing offsets through cascaded repeaters cannot exceed worst-case clock offset requirements. + +With this approach, timing characteristics such as the jitter and wander of the reconstructed client signal depend primarily on the quality of the local reference clock. The local reference clock is protocol rate-specific (e.g., gigabit Ethernet, FC and ESCON do not share common frequencies). + +##### **8.4.1.1.2 Rate adaptation from the transported client signal** + +Client signals are provided at a smooth protocol-specific clock rate on ingress. While there may be gaps in the client data packets themselves, these are filled with an IPG at a constant clock rate. Transparent mapping preserves all of the client data, control and IPG information when re-coding it using 64B/65B (assuming no client LOS or loss of character synchronization occurs). However, the recoded data is then mapped into GFP frames with 65B\_PAD stuffing to rate-adapt to the higher bandwidth transport payload channel. GFP client management or control frames may also be inserted periodically or opportunistically between GFP client data frames. Transport frames add their own overhead (section and path overhead plus fixed stuff bytes in the case of SDH). No alignment between client data, stuffing bytes or blocks, GFP frames or transport overhead is maintained. + +On egress, clock recovery is expected to require a first-in, first-out (FIFO) and desynchronizer, where the desynchronizer would require a reference clock, phase-locked loop (PLL) and filter. Recovered clock timing would depend on some filtered version of the FIFO fill level. The FIFO itself would be subject to fairly dramatic changes in level under normal operating conditions due to the occurrence of large blocks of section/transport overhead, GFP frame overhead and GFP CMFs. Under worst-case conditions, it is possible that all of the client data "gapping" mechanisms will align into one contiguous "no client data" block. The relatively non-periodic nature of some of the gaps combined with the relative large client data source clock frequency tolerance complicate the FIFO and PLL design. + +The advantage of this desynchronizer approach is that no protocol-specific knowledge is required to recover the client clock on egress. + +The jitter and wander timing characteristics of the reconstructed client signal depend primarily on the design of the clock recovery system. With a more complex design, a wide range of client rates may be supported with a single design. + +#### **8.4.1.2 Client-specific rate adaptation aspects** + +On egress, transparently transported client signals must be reconstructed and output in a manner that is compliant with the physical interface requirements specific to each protocol. Regardless of the selected client egress timing approach, protocol-specific timing requirements must be met, as defined in applicable standards for each client protocol. Clauses 8.4.1.2.1 to 8.4.1.2.5 identify key applicable requirements, but other protocol-specific requirements may apply. + +##### 8.4.1.2.1 Fibre channel payload + +FC full rate output data rate (after 8B/10B encoding) shall be $531.25, 1\,062.5, 2\,125$ or $4\,250$ Mbit/s $\pm 100$ ppm, as specified in clause 5.1 of [ANSI INCITS 230]. Output signal timing requirements are further specified in clauses 6.1.1 (single-mode optical output interface), 6.2.1 (multi-mode optical output interface) and 7 (electrical cable interface) of [ANSI INCITS 230]. Output signals will normally be generated with a minimum of six primitive signals (idles and R\_RDY) between frames, as specified in clause 17.1 of [ANSI INCITS 230]. If rate adaptation is performed using FC idle insert/removal, rate adaptation shall be applied such that the destination receives at least two idles preceding each frame, as specified in clause 17.1 of [ANSI INCITS 230]. + +Rate adaptation may also be required when a continuous stream of FC primitive sequences is received, where primitive sequences are defined in Table 26 of [ANSI INCITS 230]. Since a minimum of three consecutive identical primitive sequences are required to be received before the sequence is recognized (per clause 16.4.1 of [ANSI INCITS 230]), rate adaptation by inserting one replica of the received four-character sequence, or deleting a received sequence, shall only occur after three consecutive identical sequences have been received and retransmitted. + +Depending on implementation, a continuous stream of 10B\_ERR neutral disparity characters could be generated at egress, although rate adaptation is still required here. In this case, rate adaptation may be performed by removing or inserting a 10B\_ERR neutral disparity character after 12 consecutive 10B\_ERR characters have been received and retransmitted. + +##### 8.4.1.2.2 ESCON payload + +ESCON output data rate (after 8B/10B encoding) shall be $200$ Mbit/s $\pm 0.04$ Mbit/s, as specified in clause 5.1.2 of [ANSI INCITS 296]. Output signal timing requirements are further specified in clauses 5.2.1 (multi-mode output interface) and 5.3.1 (single-mode output interface) of [ANSI INCITS 296]. Output signals will normally be generated with a minimum of four idle characters (K28.5) between data frames, as specified in clause 6.3 of [ANSI INCITS 296]. According to the rules of clause 7.2 of [ANSI INCITS 296], if rate adaptation is performed using ESCON idle insert/removal, such adaptation is limited to one insert/removal event between any two frames, and said insert/removal event consists of the addition or removal of either one or two idle characters. However, one insert/removal event between frames may not provide for sufficient rate correction capability when the interval between frames becomes sufficiently large. Therefore, for GFP-T egress adaptation purposes, any number of insert/removal events is permitted between frames, provided that such events occur no more frequently than once every 2 500 characters on average and do not result in fewer than two idles remaining between frames. Rate adaptation may also be required when a continuous stream of ordered set sequences is received, where ordered set sequences are defined in Table 15 of [ANSI INCITS 296]. Since a minimum of eight consecutive sequences are required to be received before the sequence is recognized (per clause 6.3 of [ANSI INCITS 296]), rate adaptation by inserting a replica of the received two-character sequence, or deleting a received sequence shall only occur after eight consecutive identical sequences have been received and retransmitted. + +Depending on implementation, a continuous stream of 10B\_ERR neutral disparity characters could be generated at egress, although rate adaptation is still required here. In this case, rate adaptation may be performed by removing or inserting a 10B\_ERR neutral disparity character after 12 consecutive 10B\_ERR characters have been received and retransmitted. + +##### 8.4.1.2.3 FICON payload + +The timing requirements for FICON are the same as those specified for FC in [ANSI INCITS 230]. + +##### 8.4.1.2.4 Full-duplex gigabit Ethernet payload + +GbE output data rate (after 8B/10B encoding) shall be $1\,250$ Mbit/s $\pm 100$ ppm, as specified in [IEEE 802.3]. Output signal timing requirements are further specified in clauses 38.5 and 38.6 + +(1000BASE-LX optical fibre interfaces) and clauses 39.3.1 and 39.3.3 of [IEEE 802.3] [1000BASE-CX (short-haul copper interface)]. Output signals will normally be generated with a minimum IPG of 12 octets, per clause 4.4.2.3 of [IEEE 802.3]. GbE idle characters are two octets, as defined in clause 36.2.4.12 of [IEEE 802.3]. If rate adaptation is performed using full-duplex GbE Idle insert/removal, any number of /I2/s may be removed in any IPG, such that their removal shall not result in no /I/ and not less than 8 octets including /T/, /R/ and /I/ remaining between frames (see Note), as required for successful frame delineation according to Figures 36-7a and 36-7b of [IEEE 802.3]. Any number of /I2/s may be added in any IPG. Rate adaptation may also be required when a continuous stream of eight-character configuration ordered sets (consisting of alternating /C1/C2/) is received. Since a minimum of three consecutive /C1/C2/ configuration ordered sets are required to be received before the configuration set is recognized, rate adaptation, by inserting a replica of the received /C1/C2/ sequence, or deleting a received /C1/C2/ sequence shall only occur after three consecutive identical /C1/C2/ sequences have been received and retransmitted. Depending on implementation, a continuous stream of 10B\_ERR neutral disparity or transmission error (/V/) characters could be generated at egress, which still requires rate adaptation. In this case, rate adaptation may be performed by removing or replicating a 10B\_ERR or /V/ character after 12 consecutive 10B\_ERR or /V/ characters have been received and retransmitted. + +NOTE – The 8-octet limit is described in Note 3 of clause 4.4.2 of [IEEE 802.3]. Note that [IEEE 802.3] does not specify the amount of IPG shrinkage that the receiver must tolerate without frame loss. + +##### 8.4.1.2.5 DVB ASI payload + +DVB ASI output data rate (after 8B/10B encoding) shall be 270 Mbit/s $\pm$ 100 ppm, as specified in Appendix B of [EN 50083-9]. Output signal timing requirements are further specified by reference to FC specification [ANSI INCITS 230]. + +A minimum of two /K28.5/ characters must occur between Moving Picture Expert Group (MPEG) packets. Additional rate-adapting /K28.5/ characters may occur within or between packets. If rate adaptation is performed using /K28.5/ removal, rate adaptation shall be applied such that the destination receives at least two /K28.5/ characters preceding each frame, as specified in Appendix B of [EN 50083-9]. If rate adaptation requires insertion of /K28.5/ characters, they may be inserted either between or within MPEG packets. + +Depending on implementation, a continuous stream of 10B\_ERR neutral disparity characters could be received or generated at egress (e.g., in response to received client signal fail). In this case, rate adaptation may be performed by removing or inserting a 10B\_ERR neutral disparity character after 12 consecutive 10B\_ERR characters have been received and retransmitted. + +## 8.5 Asynchronous (full- or sub-rate) mapping of 8B/10B clients into GFP + +Sub-rate transport of 8B/10B block-coded clients can be accomplished via an asynchronous (full- or sub-rate) mapping of received client characters. Asynchronous transparent mapping utilizes common character-based mapping described in clause 8.1 as well as the client-specific processes of clauses 8.2.3 and 8.3. However, asynchronous mapping is typically a less transparent character-based mapping in which client-specific processing (on ingress) deletes client idle characters from the codeword stream. Flow control may be applied to ensure lossless client signal transport over transport paths offering less bandwidth than full-rate client signals support. Client-specific requirements described in 8.5.1 are applied before mapping and encapsulating (in the ingress direction) and after de-mapping, extracting 64B/65B blocks and decoding them into 8B/10B block codes (in the egress direction). + +### 8.5.1 Fibre channel specific aspects for asynchronous GFP-T mapping + +FC client-specific aspects for asynchronous GFP-T mapping are for further study. + +# Appendix I + +## Examples of functional models for GFP applications + +(This appendix does not form an integral part of this Recommendation.) + +This appendix presents some examples of functional models for GFP applications. In the absence of layer network architectures for data layer networks (e.g., IP and Ethernet), the models presented are for illustration purposes only. + +GFP can be deployed in transport NEs (e.g., SDH) and in data NEs (e.g., IP, Ethernet). + +In the former case, a physical data interface (Ethernet or storage area network type) is provided as a tributary interface port on the transport NE. If the physical data signal is an 8B/10B coded signal, it can be transported through the transport network as a transparent stream using GFP-T mapping (Figure I.1). If only a part of the physical interface bandwidth is carrying traffic and only this traffic is to be transported through the transport network, the physical data interface signal is terminated, data PDUs are extracted and forwarded via GFP-F mapping over a VC-m-Xv, VC-n, VC-n-Xc or VC-n-Xv signal (Figure I.2). + +In the latter case, GFP processing is performed between the IP router (Ethernet switch) fabric and the, e.g., STM-N interface port functions (Figures I.3 and I.4). The FC tributary interface port using FC-BBW\_SONET and GFP-F mapping in an SDH NE is shown in Figure I.5. + +![Figure I.1: Functional model for FC/ES/FI/GE tributary interface port using full-rate GFP-T mapping. The diagram shows two vertical paths: a physical path on the left and a GFP-T mapping path on the right. The left path includes 8B/10B decoding and clock recovery leading to a physical signal. The right path shows PHY layer characters encapsulated in GFP frames and mapped into VC-n-Xv payload, leading to X VC-n signals.](b774dfc5023e15e9c352b97ca25a56d4_img.jpg) + +``` + +graph TD + A1["– 8B/10B (de)coding +– Clock/data recovery"] --> B1["PHY-t/CBR-t"] + B1 --> C1["PHY-t"] + C1 --> D1["Physical signal"] + + A2["– PHY layer CHARACTERS (data, control) encapsulated in fixed length GFP frames +– GFP stream mapped into VC-n-Xv payload"] --> B2["Sn-X/CBR-t (GFP-T)"] + B2 --> C2["Sn-Xv"] + C2 --> D2["X VC-n signals"] + + subgraph Legend + L["t = FC (fibre channel) +ES (ESCON) +FI (FICON) +GE (1000BASE)"] + end + +``` + +G.7041-Y.1303(11)\_FI-1 + +Figure I.1: Functional model for FC/ES/FI/GE tributary interface port using full-rate GFP-T mapping. The diagram shows two vertical paths: a physical path on the left and a GFP-T mapping path on the right. The left path includes 8B/10B decoding and clock recovery leading to a physical signal. The right path shows PHY layer characters encapsulated in GFP frames and mapped into VC-n-Xv payload, leading to X VC-n signals. + +**Figure I.1 – FC/ES/FI/GE tributary interface port using full-rate GFP-T mapping in an SDH network element** + +![Figure I.2: Functional model for Ethernet tributary interface port using GFP-F mapping. The diagram shows a complex flow from Ethernet MAC frames through extraction, control character termination, and line decoding on the left, and through an Ethernet path, bridge/switch function, and GFP-F encapsulation on the right. The paths converge to physical signals and VC-n signals.](30fe9e9487585118063341332e802e98_img.jpg) + +``` + +graph TD + MAC["Ethernet MAC frames"] --> Ext["Ethernet MAC frame extraction"] + Ext --> EthS_P["EthS/EthP"] + EthS_P --> Path["Ethernet path"] + Path --> Bridge["Bridge or switch function"] + + Term["Ethernet control character termination"] --> EthS["EthS"] + EthS --> SnX["Sn[-X]/EthP (GFP-F)"] + + Line["– Ethernet-PHY line (de)coding +– Clock/data recovery"] --> PHY_EthS["PHY-t/EthS"] + PHY_EthS --> SnXv["Sn[-Xv]"] + + PHY_t["PHY-t"] --> PhysSig["Physical signal"] + SnXv --> VC_Sig["VC-n signal or X VC-n signals"] + + subgraph Legend + L2["t = Ethernet (10BASE) +Fast Ethernet (100BASE) +GigEthernet (1000BASE) +10GigEthernet (10GBASE)"] + end + +``` + +G.7041-Y.1303(11)\_FI-2 + +Figure I.2: Functional model for Ethernet tributary interface port using GFP-F mapping. The diagram shows a complex flow from Ethernet MAC frames through extraction, control character termination, and line decoding on the left, and through an Ethernet path, bridge/switch function, and GFP-F encapsulation on the right. The paths converge to physical signals and VC-n signals. + +**Figure I.2 – Ethernet tributary interface port using GFP-F mapping in an SDH network element** + +![Diagram of IP router fabric port showing encapsulation and mapping steps.](c2c4e63ebb9afc1ab64e39a159890e0f_img.jpg) + +The diagram illustrates the internal structure of an IP router fabric port. On the left, a grid represents the 'IP router fabric' with an 'Interface port' at the bottom. A dashed line connects the fabric to a series of processing blocks on the right. The first block is an oval labeled 'IP' with 'IP router fabric' text next to it. Below this is a trapezoid labeled 'VC-n[-Xv/Xc]/IP (GFP-F)'. A list of four steps is provided to the right of this block: + + +- IP frame encapsulated in PPP frame +- PPP frame encapsulated in HDLC frame +- PPP/HDLC frame encapsulated in GFP frame +- GFP stream mapped into VC-n[-Xv/Xc] payload + + Below the first trapezoid is another trapezoid labeled 'VC-n [-Xv/Xc]'. To its right is the text 'VC-n[-Xv/Xc] path termination'. At the bottom of the signal path is the text 'VC-n[-Xc] signal or X VC-n signals'. The reference code 'G.7041-Y.1303(11)\_FI-3' is located in the bottom right corner. + +Diagram of IP router fabric port showing encapsulation and mapping steps. + +**Figure I.3 – VC-n/VC-n-Xv/VC-n-Xc port on IP router or IP router function embedded in hybrid SDH/IP equipment** + +![Diagram of Ethernet switch function port showing encapsulation and mapping steps.](cac61a60141d0335b4ae7a081f6b18d4_img.jpg) + +The diagram illustrates the internal structure of an Ethernet switch function port. On the left, a grid represents the 'Ethernet switch fabric' with an 'Interface port' at the bottom. A dashed line connects the fabric to a series of processing blocks on the right. The first block is an oval labeled 'Ethernet path' with 'Switch function' text next to it. Below this is a trapezoid labeled 'Sn[-Xv]/EthP (GFP-F)'. A list of two steps is provided to the right of this block: + + +- Ethernet MAC frame encapsulated in GFP frame +- GFP stream mapped into VC-n[-Xv] payload + + Below the first trapezoid is another trapezoid labeled 'Sn[-Xv]'. To its right is the text 'VC-n path termination or VC-n-Xv path termination'. At the bottom of the signal path is the text 'VC-n[-Xc] signal or X VC-n signals'. The reference code 'G.7041-Y.1303(11)\_FI-4' is located in the bottom right corner. + +Diagram of Ethernet switch function port showing encapsulation and mapping steps. + +**Figure I.4 – VC-n-Xv port on Ethernet switch or Ethernet switch function embedded in hybrid SDH/Ethernet equipment** + +![Diagram of Fibre channel tributary interface port using FC-BBW_SONET and GFP-F mapping.](efbdfb3d9d5a7a7782ef29e131f9f280_img.jpg) + +The diagram illustrates the internal structure of a Fibre channel tributary interface port using FC-BBW\_SONET and GFP-F mapping. It shows two parallel processing paths. The left path starts with 'FC MAC extraction/delineation n (from FC-1)' leading to a trapezoid 'FC-1/FC-2', then 'PHY-FC (FC-1) link control processing' leading to a trapezoid 'FC-1', then a list of two steps: '– FC-PHY line (de)coding' and '– Clock/data recovery' leading to a trapezoid 'PHY-FC/FC-1', then 'PHY-FC (FC-0) e.g., 1G, 2G, 4G and 10G FC' leading to a trapezoid 'PHY-FC', and finally 'Physical signal'. The right path starts with 'FC MAC extraction (from FC-BBW\_SONET)' leading to a trapezoid 'FC-BBW\_SONET /FC-2', then 'FC-BBW\_SONET termination' leading to a trapezoid 'FC-BBW', then a list of three steps: '– FC-BBW\_SONET frames encapsulated in GFP-F', '– GFP frame stream mapped in VC-n/VC-n-Xv', and 'VC-n/VC-n-Xv path termination' leading to a trapezoid 'Sn[-X]/FC-BBW (GFP-F)', then a trapezoid 'Sn[-X]', and finally 'VC-n or signal or X VC-n signals'. The reference code 'G.7041-Y.1303(11)\_FI-5' is located in the bottom right corner. + +Diagram of Fibre channel tributary interface port using FC-BBW\_SONET and GFP-F mapping. + +**Figure I.5 – Fibre channel tributary interface port using FC-BBW\_SONET and GFP-F mapping in an SDH network element** + +# Appendix II + +## Sample GFP payload types + +(This appendix does not form an integral part of this Recommendation.) + +Table II.1 – GFP payload types + +| Payload type identifier (binary) | Payload frame check sequence identifier (binary) | Extension header identifier (binary) | User payload identifier (binary) | Type | GFP frame payload area | Length of extension headers | +|----------------------------------|--------------------------------------------------|--------------------------------------|----------------------------------|-------|---------------------------------------------------------------------|-----------------------------| +| Type bits <15:13> | Type bit <12> | Type bits <11:8> | Type bits <7:0> | (HEX) | | (No. octets) | +| 000 | 0 | xxxx | 0000 0000 | 0x00 | Reserved | | +| 000 | 1 | xxxx | 0000 0000 | 1x00 | Reserved | | +| 000 | 0 | 0000 | 0000 0001 | 0001 | Ethernet with null extension header and no pFCS | 0 | +| 000 | 0 | 0000 | 0000 0010 | 0002 | PPP with null extension header and no pFCS | 0 | +| 000 | 0 | 0001 | 0000 0001 | 0101 | Ethernet with linear extension header and no pFCS | 4 | +| 000 | 0 | 0001 | 0000 0010 | 0102 | PPP with linear extension header and no pFCS | 4 | +| 000 | 0 | 0010 | 0000 0001 | 0201 | Ethernet with ring extension header and no pFCS | 18 | +| 000 | 0 | 0010 | 0000 0010 | 0202 | PPP with ring extension header and no pFCS | 18 | +| 000 | 0 | 0000 | 0000 0011 | 0003 | Transparent fibre channel with null extension header and no pFCS | 0 | +| 000 | 0 | 0000 | 0000 0100 | 0004 | Transparent FICON with null extension header and no pFCS | 0 | +| 000 | 0 | 0000 | 0000 0101 | 0005 | Transparent ESCON with null extension header and no pFCS | 0 | +| 000 | 0 | 0000 | 0000 0110 | 0006 | Transparent gigabit Ethernet with null extension header and no pFCS | 0 | +| 1xx | x | xxxx | xxxx xxxx | – | Reserved | – | +| x1x | x | xxxx | xxxx xxxx | – | Reserved | – | +| xx1 | x | xxxx | xxxx xxxx | – | Reserved | – | + +# Appendix III + +## GFP frame example illustrating transmission order and CRC calculation + +(This appendix does not form an integral part of this Recommendation.) + +## III.1 Worked example for a GFP-F frame + +Transmit: + +User\_data → GFP\_source adaptation → scramble and DC\_balance → SDH + +Receive: + +SDH → un\_DC\_balance and unscramble → GFP\_sink decapsulation → client data + +The following worked example shows the encapsulation of a 64-byte Ethernet frame with linear header and FCS, before DC balancing and self-synchronous scrambling. The Ethernet data octets are mapped to the GFP octet according to a reversed transmission bit order relative to the Ethernet transmission bit order (i.e., bit 0 in clause 3 of [IEEE 802.3] corresponds to GFP octet bit 8, and bit 7 in clause 3 of [IEEE 802.3] corresponds to GFP octet bit 1). The hex values in this example are oriented such that the MSB is on the left and the LSB right. + +| Byte | Field | Value (hex) | Comment | +|------|------------|-------------|---------------------------------------------------------------| +| 1 | PLI[15:8] | 00 | ; PLI = Length { payload header + payload information field } | +| 2 | PLI[7:0] | 48 | ; = 8 + 64 = 72 bytes | +| 3 | cHEC[15:8] | C9 | ; | +| 4 | cHEC[7:0] | CC | ; | +| 5 | TYPE[15:8] | 01 | ; [15:13] = '000' (client data) | +| 6 | TYPE[7:0] | 01 | ; [12] = '0' (pFCS disabled) | +| 7 | tHEC[15:8] | 23 | ; [11:8] = '0001' (linear header) | +| 8 | tHEC[7:0] | 10 | ; [7:0] = '00000001' (Ethernet) | +| 9 | EHDR[15:8] | 80 | ; CID[07:00] = 0x8000 (the value is just an example) | +| 10 | EHDR[7:0] | 00 | ; SPARE[7:0] | +| 11 | eHEC[15:8] | 1B | ; eHEC calculated over CID,SPARE | +| 12 | eHEC[7:0] | 98 | ; End extension header | +| 13 | DATA | FF | ; 1d Ethernet DA = 0xFFFFFFFFFFFF | +| 14 | DATA | FF | ; 2d | +| 15 | DATA | FF | ; 3d | +| 16 | DATA | FF | ; 4d | +| 17 | DATA | FF | ; 5d | +| 18 | DATA | FF | ; 6d | +| 19 | DATA | 06 | ; 7d Ethernet SA = 0x060504030201 | +| 20 | DATA | 05 | ; 8d | +| 21 | DATA | 04 | ; 9d | +| 22 | DATA | 03 | ; 10d | +| 23 | DATA | 02 | ; 11d | + +| Byte | Field | Value (hex) | Comment | +|------|-------|-------------|----------------------------| +| 24 | DATA | 01 | ; 12d | +| 25 | DATA | 00 | ; 13d Ethernet TYPE/LENGTH | +| 26 | DATA | 2E | ; 14d | +| 27 | DATA | 00 | ; 15d Ethernet payload | +| 28 | DATA | 01 | ; 16d | +| 29 | DATA | 02 | ; 17d | +| 30 | DATA | 03 | ; 18d | +| 31 | DATA | 04 | ; 19d | +| 32 | DATA | 05 | ; 20d | +| 33 | DATA | 06 | ; 21d | +| 34 | DATA | 07 | ; 22d | +| 35 | DATA | 08 | ; 23d | +| 36 | DATA | 09 | ; 24d | +| 37 | DATA | 0A | ; 25d | +| 38 | DATA | 0B | ; 26d | +| 39 | DATA | 0C | ; 27d | +| 40 | DATA | 0D | ; 28d | +| 41 | DATA | 0E | ; 29d | +| 42 | DATA | 0F | ; 30d | +| 43 | DATA | 10 | ; 31d | +| 44 | DATA | 11 | ; 32d | +| 45 | DATA | 12 | ; 33d | +| 46 | DATA | 13 | ; 34d | +| 47 | DATA | 14 | ; 35d | +| 48 | DATA | 15 | ; 36d | +| 49 | DATA | 16 | ; 37d | +| 50 | DATA | 17 | ; 38d | +| 51 | DATA | 18 | ; 39d | +| 52 | DATA | 19 | ; 40d | +| 53 | DATA | 1A | ; 41d | +| 54 | DATA | 1B | ; 42d | +| 55 | DATA | 1C | ; 43d | +| 56 | DATA | 1D | ; 44d | +| 57 | DATA | 1E | ; 45d | +| 58 | DATA | 1F | ; 46d | +| 59 | DATA | 20 | ; 47d | +| 60 | DATA | 21 | ; 48d | +| 61 | DATA | 22 | ; 49d | +| 62 | DATA | 23 | ; 50d | +| 63 | DATA | 24 | ; 51d | +| 64 | DATA | 25 | ; 52d | + +| Byte | Field | Value (hex) | Comment | +|------|-------|-------------|-------------------------------------------| +| 65 | DATA | 26 | ; 53d | +| 66 | DATA | 27 | ; 54d | +| 67 | DATA | 28 | ; 55d | +| 68 | DATA | 29 | ; 56d | +| 69 | DATA | 2A | ; 57d | +| 70 | DATA | 2B | ; 58d | +| 71 | DATA | 2C | ; 59d | +| 72 | DATA | 2D | ; 60d | +| 73 | DATA | DE | ; 61d Ethernet FCS computed over 60 bytes | +| 74 | DATA | E1 | ; 62d | +| 75 | DATA | 90 | ; 63d | +| 76 | DATA | D0 | ; 64d | + +The core header is XORed with the DC Barker code, the rest of the GFP frame is unchanged. + +| Byte | Field | Value (hex) | Comment | +|------|------------|-------------|-------------| +| 1 | PLI[15:8] | B6 | ; 00 XOR B6 | +| 2 | PLI[7:0] | E3 | ; 48 XOR AB | +| 3 | cHEC[15:8] | F8 | ; C9 XOR 31 | +| 4 | cHEC[7:0] | 2C | ; CC XOR E0 | +| 5 | ... | | | + +The following example shows the calculation of the cHEC for PLI[15:0] = 0x0048. The polynomial is $G(x) = x^{16} + x^{12} + x^5 + 1$ . The PLI is shifted into the CRC-16 calculator with PLI[15:8] first, then PLI[7:0], MSB first for each octet. + +$x^{15}$                      ...                      $x^0$ + +0000000000000000 ← CRC-16 initial state + +Input bit    1   0001000000100001 ← CRC-16 after input bit +                   0   0010000001000010 +                   0   0100000010000100 +                   1   1001000100101001 +                   0   0011001001110011 +                   0   0110010011100110 +                   0   1100100111001100 + +Transmit the CRC-16 starting from $x^{15}$ gives the GFP octets cHEC[15:0] = 0xC9CC. + +The GFP frame is input to the $x^{43}+1$ scrambler in network bit order (MSB first). Starting with the first byte of the TYPE field (the core header is not scrambled): + +Bit #1 TYPE[15] + +Bit #2 TYPE[14] + +Bit #3 TYPE[13] + +... + +## III.2 Worked example for a GFP-T superblock CRC calculation + +This clause provides a worked example calculation of the CRC-16 for a GFP-T superblock. For this example, the first octet of the superblock (octet 1,1) contains the value 80 hex (i.e., a 1 in the MSB position), and all other octets in the superblock, including the L-bit octet, contain all 0s. The resulting CRC-16 value will be 1001 1010 1010 0010 (9AA2 hex) in bits CRC-1-CRC-16, respectively. + +## III.3 Worked example for a GFP-F encapsulated MPLS frame + +The following worked example shows the encapsulation of a 28-byte MPLS frame with null extension header and FCS, before DC balancing and self-synchronous scrambling. The same methods as in clause III.1 are used for core and type header CRC calculation and the core header encoding. The hex values in this example are oriented such that the MSB is on the left and the LSB right. + +| Byte | Field | Value (hex) | Comment | +|------|------------|-------------|----------------------------------------------------------------------| +| 1 | PLI[15:8] | 00 | ; PLI = Length { payload header + payload information field + pFCS } | +| 2 | PLI[7:0] | 24 | ; = 4 + 28 + 4 = 36 bytes | +| 3 | cHEC[15:8] | 64 | ; | +| 4 | cHEC[7:0] | E6 | ; | +| 5 | TYPE[15:8] | 10 | ; [15:13] = '000' (client data) | +| 6 | TYPE[7:0] | 0D | ; [12] = '1' (pFCS enabled) | +| 7 | tHEC[15:8] | D2 | ; [11:8] = '0000' (null extension header) | +| 8 | tHEC[7:0] | DE | ; [7:0] = '00001101' (MPLS) | +| 9 | DATA | 00 | ; 1d MPLS headers | +| 10 | DATA | 01 | ; 2d | +| 11 | DATA | 70 | ; 3d | +| 12 | DATA | FE | ; 4d | +| 13 | DATA | 00 | ; 5d | +| 14 | DATA | 01 | ; 6d | +| 15 | DATA | 21 | ; 7d | +| 16 | DATA | FF | ; 8d | +| 17 | DATA | 49 | ; 9d MPLS payload | +| 18 | DATA | 54 | ; 10d | +| 19 | DATA | 55 | ; 11d | +| 20 | DATA | 2D | ; 12d | +| 21 | DATA | 54 | ; 13d | + +| Byte | Field | Value (hex) | Comment | +|------|------------|-------------|-----------------------------------------| +| 22 | DATA | 20 | ; 14d | +| 23 | DATA | 52 | ; 15d | +| 24 | DATA | 65 | ; 16d | +| 25 | DATA | 63 | ; 17d | +| 26 | DATA | 20 | ; 18d | +| 27 | DATA | 47 | ; 19d | +| 28 | DATA | 2E | ; 20d | +| 29 | DATA | 37 | ; 21d | +| 30 | DATA | 30 | ; 22d | +| 31 | DATA | 34 | ; 23d | +| 32 | DATA | 31 | ; 24d | +| 33 | DATA | 20 | ; 25d | +| 34 | DATA | 47 | ; 26d | +| 35 | DATA | 46 | ; 27d | +| 36 | DATA | 50 | ; 28d | +| 37 | FCS[31:24] | 87 | ; First byte of GFP pFCS | +| 38 | FCS[23:16] | 64 | ; Covers only payload information field | +| 39 | FCS[15:8] | 8B | ; (i.e., 28 bytes) | +| 40 | FCS[7:0] | BB | ; Last byte of GFP pFCS. | + +The core header is XORed with the DC Barker code, the rest of the GFP frame is unchanged. + +| Byte | Field | Value (hex) | Comment | +|------|------------|-------------|-------------| +| 1 | PLI[15:8] | B6 | ; 00 XOR B6 | +| 2 | PLI[7:0] | 8F | ; 24 XOR AB | +| 3 | cHEC[15:8] | 55 | ; 64 XOR 31 | +| 4 | cHEC[7:0] | 06 | ; E6 XOR E0 | +| 5 | ... | | | + +# Appendix IV + +## Number of superblocks used in transparent GFP + +(This appendix does not form an integral part of this Recommendation.) + +## IV.1 Introduction + +In GFP-T, there is an integer number ( $N$ ) of 536-bit superblocks in a client data frame. The value of $N$ must be chosen so that the efficiency of the client data bits relative to the GFP frame overhead bits allows enough bandwidth to transport the client data signal. The value of $N$ can be chosen to allow enough additional SBW in the channel for the transport of CMFs and MCFs. The minimum values of $N$ are shown here as a function of the various overhead bits and the number of CMFs (CMFs) or MCFs that are allowed to be transmitted between successive GFP-T client data frames. + +## IV.2 Calculation of spare bandwidth + +The SBW in a GFP-T channel is specified as: + +$$\begin{aligned}\text{SBW} &= (\text{minimum bit rate for carrying client bits in the channel}) - (\text{client data bit rate}) \\ &= (\text{minimum channel bit rate}) (\text{ratio of client data bits to total bits}) - (\text{client data bit rate})\end{aligned}$$ + +where: + +the client data bit rate is the data rate after decoding the block line code (e.g., 8B/10B), and the total number of bits in the channel is the client data bits plus all GFP-T overhead bits. + +SBW as a function of $N$ is: + +$$\begin{aligned}\text{SBW}(N) &= (\text{Min.Chan.rate}) \left( \frac{\text{client data bits/GFP-T frame}}{\text{total bits/GFP-T frame}} \right) - (\text{Max. client data rate}) \\ \text{SBW}(N) &= \frac{(512)(N)(\text{ChBW}_{\min})}{\text{GFPOH} + (536)(N)} - \text{CSBW}_{\max}\end{aligned}$$ + +where: + +$\text{ChBW}_{\min}$ = transport channel bandwidth with slowest end of the transport clock tolerance + +$\text{CSBW}_{\max}$ = client signal data rate with fastest end of the client clock tolerance + +$\text{GFPOH}$ = the number of GFP overhead bits + +The minimum value of $N$ is the smallest $N$ such that $\text{SBW}(N) > 0$ : + +$$N_{\min} = \left\lceil \frac{(\text{CSBW}_{\max})(\text{GFPOH})}{(512)(\text{ChBW}_{\min}) - (536)(\text{CSBW}_{\max})} \right\rceil$$ + +where the notation $\lceil x \rceil$ represents the smallest integer that is $\geq x$ . + +The minimum VC path sizes with their associated $N_{\min}$ values are shown in Table IV.1. + +**Table IV.1 – SDH path capacity and number of superblocks per transparent GFP frame** + +| Client unencoded data rate | Example client signal | VC path size | Min. number of superblocks/GFP frame | +|----------------------------|-----------------------|--------------|--------------------------------------| +| 160 Mbit/s | ESCON | VC-3-4v | 1 | +| 216 Mbit/s | DVB ASI | VC-4-2v | 1 | +| 425 Mbit/s | Fibre channel | VC-4-3v | 13 | +| 850 Mbit/s | Fibre channel/FICON | VC-4-6v | 13 | +| 1 000 Mbit/s | Gigabit Ethernet | VC-4-7v | 95 | +| 1 700 Mbit/s | Fibre channel | VC-4-12v | 13 | +| 3 400 Mbit/s | Fibre channel | VC-4-24v | 13 | + +NOTE – The minimum number of superblocks shown here assumes a null extension header and no optional pFCS. + +## IV.3 Calculation of available bandwidth for CMFs and MCFs + +For compactness, CMF is used in this clause to indicate either CMFs or MCFs. The bandwidth available to be used for CMFs is the SBW subject to the constraints on the number of CMFs that can be transmitted between two client data frames. If there were no restrictions on the number of CMFs that could be transmitted, then the largest allowable value of $N$ would give the largest amount of bandwidth available for CMFs, where: + +$$\begin{aligned} + N_{\max} &= (65\,536 - \text{GFPOH})/67 \\ + &= 978 \text{ with no extension header or pFCS; and} \\ + &= 977 \text{ with extension header or pFCS} + \end{aligned}$$ + +In order to minimize the latency and buffering requirements associated with the ingress to the GFP-T source adaptation process, it is desirable to send no more than one CMF between client data frames. The longer the client data frames are, the fewer the opportunities per second exist for transmitting CMFs (i.e., the fewer inter-client data frame gaps exist for sending CMFs). As a result, as $N$ increases, the number of CMF transmission opportunities decreases, and hence the available CMF bandwidth decreases. With this restriction, the optimum value of $N$ is the one that fills the entire bandwidth with exactly one CMF per client data frame. A smaller value of $N$ would reduce the SBW such that it is not adequate to allow a CMF between each client data frame. A larger value of $N$ would result in fewer CMFs per second. In general, if $m$ CMFs are allowed to be transmitted between client data frames, the available CMF bandwidth is: + +$$\begin{aligned} + \text{CMFBW}(N, m) &= (\text{CMF/second})(\text{bits/CMF}) \\ + \text{CMFBW}(N, m) &= \frac{(\text{ChBW}_{\min})(\text{CMFL})(m)}{(m)(\text{CMFL}) + \text{GFPOH} + (536)(N)} + \end{aligned}$$ + +where: + +CMFL = CMF frame length + +$m$ = the number of CMFs that can be transmitted between client data frames, and there is a constraint that: + +$$\frac{(512)(N)(\text{ChBW}_{\min})}{\text{GFPOH} + (536)(N) + (m)(\text{CMFL})} \geq \text{CSBW}_{\max}$$ + +The actual payload bandwidth of the CMFs is the ratio of the CMF payload area to the total CMF frame length: + +$$\text{CMPLBW} = [\text{CMFBW}(N, m)] \left( \frac{\text{CMFPAL}}{\text{CMFL}} \right)$$ + +where: + +CMPLBW = the CMF usable payload bandwidth + +CMFPAL = the number of bits in the CMF payload area used for CMF payload (i.e., the payload area minus the pFCS, if it is used) + +For a given value of $m$ , the value of $N$ that gives the most useable CMF bandwidth will be the integer closest to: + +$$N_{\text{opt}} = \frac{(\text{CSBW}_{\max}) [\text{GFPOH} + (m)(\text{CMFL})]}{(512)(\text{ChBW}_{\min}) - (536)(\text{CSBW}_{\max})}$$ + +# Appendix V + +## Bandwidth requirements for Ethernet transport + +(This appendix does not form an integral part of this Recommendation.) + +This appendix shows the transport bandwidth requirements for client data over Ethernet over GFP over a synchronous optical network (SONET) as a function of the Ethernet MAC rate, the client payload field length, whether the network has inserted a VLAN tag, and whether the GFP pFCS is used. This information is shown in Tables V.1 to V.4. + +NOTE – The MAC bit rate in Tables V.1 to V.3 is the actual bit rate of the Ethernet MAC frames after the removal of the 12-byte IPG plus 7-byte preamble + 1-byte SFD. In other words, MAC bit rate = (Ethernet interface rate) (No. of bits in the MAC frame)/(No. of bits in the MAC frame + 12-byte IPG + 7-byte preamble + 1-byte SFD). The calculations in Table V.4 are the same, except that the 10 Gbit Ethernet uses a 5-byte minimum IPG instead of 12 bytes. + +**Table V.1 – Maximum (un)tagged MAC bit rate per "10 Mbit/s" MAC server signal** + +| | | | Payload bit rate (nominal bit rate for Ethernet) | | | | | | | | | +|---------|----------|------------------|------------------------------------------------------------------------|----------|------------|----------|------------|----------|------------|----------|------------| +| | | | 10 000 | 9 600 | 11 200 | 8 704 | 10 880 | | | | | +| | | | MAC bit rate (kbit/s), throughput (%) relative to maximum MAC bit rate | | | | | | | | | +| GFP-FCS | VLAN tag | MAC-size (bytes) | 10Base-T | VC-11-6v | Throughput | VC-11-7v | Throughput | VC-12-4v | Throughput | VC-12-5v | Throughput | +| 0 | 0 | 64 | 7 619 | 8 533 | 112.0 | 9 956 | 131 | 7 737 | 101.5 | 9 671 | 127 | +| 0 | 0 | 128 | 8 649 | 9 055 | 104.5 | 10 541 | 122 | 8 192 | 94.7 | 10 240 | 118 | +| 0 | 0 | 256 | 9 275 | 9 309 | 100.4 | 10 861 | 117 | 8 440 | 91.0 | 10 550 | 114 | +| 0 | 0 | 512 | 9 624 | 9 452 | 98.2 | 11 028 | 115 | 8 570 | 89.0 | 10 713 | 111 | +| 0 | 0 | 1 024 | 9 808 | 9 526 | 97.1 | 11 113 | 113 | 8 637 | 88.1 | 10 796 | 110 | +| 0 | 0 | 1 518 | 9 870 | 9 550 | 96.8 | 11 141 | 113 | 8 658 | 87.7 | 10 823 | 110 | +| 0 | 0 | 9 618 | 9 979 | 9 592 | 96.1 | 11 191 | 112 | 8 697 | 87.1 | 10 871 | 109 | +| 0 | 1 | 64 | 7 727 | 8 589 | 111.2 | 10 021 | 130 | 7 788 | 100.8 | 9 735 | 126 | +| 0 | 1 | 128 | 8 684 | 9 051 | 104.2 | 10 560 | 122 | 8 207 | 94.5 | 10 258 | 118 | +| 0 | 1 | 256 | 9 286 | 9 313 | 100.3 | 10 866 | 117 | 8 444 | 90.9 | 10 555 | 114 | +| 0 | 1 | 512 | 9 627 | 9 453 | 98.2 | 11 029 | 115 | 8 571 | 89.0 | 10 714 | 111 | +| 0 | 1 | 1 024 | 9 809 | 9 526 | 97.1 | 11 114 | 113 | 8 637 | 88.0 | 10 796 | 110 | +| 0 | 1 | 1 518 | 9 870 | 9 550 | 96.8 | 11 141 | 113 | 8 658 | 87.7 | 10 823 | 110 | +| 0 | 1 | 9 618 | 9 979 | 9 592 | 96.1 | 11 191 | 112 | 8 697 | 87.1 | 10 871 | 109 | + +NOTE 1 – GFP-FCS; no = 0, yes = 1. VLAN tag; value gives the number of VLAN tags (no VLAN tag = 0). + +NOTE 2 – Encapsulation overhead; 20 bytes for physical Ethernet interface (7-byte preamble, 1-byte SFD and 12-byte minimum IPG). 8-byte encapsulation overhead for GFP without GFP-FCS and 12-byte encapsulation overhead for GFP with GFP-FCS. + +**Table V.2 – Maximum (un)tagged MAC bit rate per "100 Mbit/s" MAC server signal** + +| | | | Payload bit rate (nominal bit rate for Ethernet) | | | | | +|---------|----------|------------------|------------------------------------------------------------------------|---------|------------|---------|------------| +| | | | 100 000 | 96 768 | | 149 760 | | +| | | | MAC bit rate (kbit/s), throughput (%) relative to maximum MAC bit rate | | | | | +| GFP-FCS | VLAN tag | MAC-size (bytes) | 100Base-T | VC-3-2v | Throughput | VC-4 | Throughput | +| 0 | 0 | 64 | 76 190 | 86 016 | 100.0 | 133 120 | 100.0 | +| 0 | 0 | 128 | 86 486 | 91 076 | 100.0 | 140 951 | 100.0 | +| 0 | 0 | 256 | 92 754 | 93 836 | 100.0 | 145 222 | 100.0 | +| 0 | 0 | 512 | 96 241 | 95 279 | 99.0 | 147 456 | 100.0 | +| 0 | 0 | 1 024 | 98 084 | 96 018 | 97.9 | 148 599 | 100.0 | +| 0 | 0 | 1 518 | 98 700 | 96 261 | 97.5 | 148 975 | 100.0 | +| 0 | 0 | 9 618 | 99 792 | 96 688 | 96.9 | 149 636 | 100.0 | +| 0 | 1 | 64 | 77 273 | 86 582 | 100.0 | 133 996 | 100.0 | +| 0 | 1 | 128 | 86 842 | 91 238 | 100.0 | 141 202 | 100.0 | +| 0 | 1 | 256 | 92 857 | 93 879 | 100.0 | 145 290 | 100.0 | +| 0 | 1 | 512 | 96 269 | 95 291 | 99.0 | 147 474 | 100.0 | +| 0 | 1 | 1 024 | 98 092 | 96 021 | 97.9 | 148 604 | 100.0 | +| 0 | 1 | 1 518 | 98 703 | 96 262 | 97.5 | 148 977 | 100.0 | +| 0 | 1 | 9 618 | 99 793 | 96 688 | 96.9 | 149 636 | 100.0 | + +NOTE 1 – GFP-FCS; no = 0, yes = 1. VLAN tag; value gives the number of VLAN tags (no VLAN tag = 0). + +NOTE 2 – Encapsulation overhead; 20 bytes for physical Ethernet interface (7-byte preamble, 1-byte SFD and 12-byte minimum IPG). 8-byte encapsulation overhead for GFP without GFP-FCS and 12-byte encapsulation overhead for GFP with GFP-FCS. + +**Table V.3 – Maximum (un)tagged MAC bit rate per "1 Gbit/s" MAC server signal** + +| | | | Payload bit rate (nominal bit rate for Ethernet) | | | | | +|---------|----------|------------------|------------------------------------------------------------------------|---------|------------|-----------|------------| +| | | | 1 000 000 | 898 560 | | 1 048 320 | | +| | | | MAC bit rate (kbit/s), throughput (%) relative to maximum MAC bit rate | | | | | +| GFP-FCS | VLAN tag | MAC-size (bytes) | 1000Base-X | VC-4-6v | Throughput | VC-4-7v | Throughput | +| 0 | 0 | 64 | 761 905 | 798 720 | 100.0 | 931 840 | 100.0 | +| 0 | 0 | 128 | 864 865 | 845 704 | 97.8 | 986 654 | 100.0 | +| 0 | 0 | 256 | 927 536 | 871 331 | 93.9 | 1 016 553 | 100.0 | +| 0 | 0 | 512 | 962 406 | 884 736 | 91.9 | 1 032 192 | 100.0 | +| 0 | 0 | 1 024 | 980 843 | 891 594 | 90.9 | 1 040 193 | 100.0 | +| 0 | 0 | 1 518 | 986 996 | 893 849 | 90.6 | 1 042 824 | 100.0 | +| 0 | 0 | 9 618 | 997 925 | 897 813 | 90.0 | 1 047 449 | 100.0 | +| 0 | 1 | 64 | 772 727 | 803 975 | 100.0 | 937 971 | 100.0 | +| 0 | 1 | 128 | 868 421 | 847 214 | 97.6 | 988 416 | 100.0 | +| 0 | 1 | 256 | 928 571 | 871 737 | 93.9 | 1 017 027 | 100.0 | +| 0 | 1 | 512 | 962 687 | 884 842 | 91.9 | 1 032 315 | 100.0 | +| 0 | 1 | 1 024 | 980 916 | 891 621 | 90.9 | 1 040 225 | 100.0 | +| 0 | 1 | 1 518 | 987 030 | 893 862 | 90.6 | 1 042 839 | 100.0 | +| 0 | 1 | 9 618 | 997 926 | 897 814 | 90.0 | 1 047 449 | 100.0 | + +NOTE 1 – GFP-FCS; no = 0, yes = 1. VLAN tag; value gives the number of VLAN tags (no VLAN tag = 0). + +NOTE 2 – Encapsulation overhead; 20 bytes for physical Ethernet interface (7-byte preamble, 1-byte SFD and 12-byte minimum IPG). 8-byte encapsulation overhead for GFP without GFP-FCS and 12-byte encapsulation overhead for GFP with GFP-FCS. + +**Table V.4 – Maximum (un)tagged MAC bit rate per "10 Gbit/s" MAC server signal** + +| | | | Payload bit rate (nominal bit rate for Ethernet) | | | | | | | +|----------------|-----------------|-------------------------|-------------------------------------------------------------------------------|------------------|-------------------|------------------|-------------------|-------------|-------------------| +| | | | 10 000 000 | 9 884 160 | 9 953 280 | 9 995 277 | | | | +| | | | MAC bit rate (kbit/s), throughput (%) relative to maximum MAC bit rate | | | | | | | +| GFP-FCS | VLAN tag | MAC-size (bytes) | 10GBase-R | VC-4-66v | Throughput | ODU1-4v | Throughput | ODU2 | Throughput | +| 0 | 0 | 64 | 8 311 688 | 8 785 920 | 100.0 | 8 847 360 | 100.0 | 8 884 691 | 100.0 | +| 0 | 0 | 128 | 9 078 014 | 9 302 739 | 100.0 | 9 367 793 | 100.0 | 9 407 319 | 100.0 | +| 0 | 0 | 256 | 9 516 729 | 9 584 640 | 100.0 | 9 651 665 | 100.0 | 9 692 390 | 100.0 | +| 0 | 0 | 512 | 9 752 381 | 9 732 096 | 99.8 | 9 800 153 | 100.0 | 9 841 503 | 100.0 | +| 0 | 0 | 1 024 | 9 874 638 | 9 807 539 | 99.3 | 9 876 123 | 100.0 | 9 917 794 | 100.0 | +| 0 | 0 | 1 518 | 9 915 088 | 9 832 343 | 99.2 | 9 901 100 | 99.9 | 9 942 877 | 100.0 | +| 0 | 0 | 9 618 | 9 986 502 | 9 875 945 | 98.9 | 9 945 008 | 99.6 | 9 986 970 | 100.0 | +| 0 | 1 | 64 | 8 395 062 | 8 843 722 | 100.0 | 8 905 566 | 100.0 | 8 943 143 | 100.0 | +| 0 | 1 | 128 | 9 103 448 | 9 319 351 | 100.0 | 9 384 521 | 100.0 | 9 424 118 | 100.0 | +| 0 | 1 | 256 | 9 523 810 | 9 589 110 | 100.0 | 9 656 167 | 100.0 | 9 696 910 | 100.0 | +| 0 | 1 | 512 | 9 754 253 | 9 733 257 | 99.8 | 9 801 322 | 100.0 | 9 842 677 | 100.0 | +| 0 | 1 | 1 024 | 9 875 120 | 9 807 834 | 99.3 | 9 876 421 | 100.0 | 9 918 093 | 100.0 | +| 0 | 1 | 1 518 | 9 915 309 | 9 832 478 | 99.2 | 9 901 237 | 99.9 | 9 943 014 | 100.0 | +| 0 | 1 | 9 618 | 9 986 508 | 9 875 949 | 98.9 | 9 945 011 | 99.6 | 9 986 974 | 100.0 | + +NOTE 1 – GFP-FCS; no = 0, yes = 1. VLAN tag; value gives the number of VLAN tags (no VLAN tag = 0). + +NOTE 2 – Encapsulation overhead; 13 bytes for physical Ethernet interface (7-byte preamble, 1-byte SFD and 5-byte minimum IPG). 8-byte encapsulation overhead for GFP without GFP-FCS and 12-byte encapsulation overhead for GFP with GFP-FCS. + +# Appendix VI + +## Ethernet physical layer defect signals + +(This appendix does not form an integral part of this Recommendation.) + +Ethernet defines a number a PHY-specific signals to indicate local and remote defects. These signals fall into two broad categories that are useful to communicate across the GFP-F link: remote defect indications and FDIs. + +Tables VI.1 and VI.2 summarize these PHY-specific signals, the conditions under which they are inserted and the PHY layer responses to receiving them. The information in these tables is provided for information only. [IEEE 802.3] is the standard for the complete specification of these signals. GFP RDI frames are sent in response to the remote defect signals of Table VI.1, and GFP FDI frames are sent in response to the local defect signals of Table VI.2. + +**Table VI.1 – Ethernet PHY remote defect signals** + +| PHY | Remote defect | Condition(s) for insertion | Response when received (per [IEEE 802.3]) | +|-------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 10BASE-FB
(clause 17 of [IEEE 802.3]) | Remote_fault is indicated continuously via a specific pattern of code violations. | Receive jabber, low light or invalid data detected, or continuous clock recovery not met. | Send idle on the link, indicate link is idle. | +| 100BASE-FX,
100BASE-TX over shielded twisted pair
(clause 24.3.2.1 of [IEEE 802.3]) | Far-end fault indication (FEFI) is indicated continuously via a specific pattern that can be detected but does not cause carrier detect. | PMD sub-layer detects a loss of signal. | Send idle on the link, indicate link is failed. | +| 10/100/1000BASE-TX over UTP
(clause 28.2.3.5 of [IEEE 802.3]) | Remote fault can be communicated via auto-negotiation. A single bit indicates the presence of a remote fault. The 'next page' capability can further indicate the type of fault as test, link loss or jabber. | Auto-negotiation is invoked immediately when a local failure is detected. The remote fault information is included in the auto-negotiation signalling. The auto-negotiation process will not complete while the local failure exists. When the local failure clears, auto-negotiation stops signalling the remote failure. | Continue auto-negotiation until it completes successfully. The remote fault is indicated in the status register. The link is considered failed until auto-negotiation is complete. | + +**Table VI.1 – Ethernet PHY remote defect signals** + +| PHY | Remote defect | Condition(s) for insertion | Response when received (per [IEEE 802.3]) | +|--------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------| +| 1000BASE-X (clause 37.2.1.5 of [IEEE 802.3]) | Remote fault is detected if the received configuration register information is all zeros for longer than the expected amount of time. The configuration register also includes bits to indicate a remote fault, but those bits are not set until the fault has cleared, so they are not useful as an indication that a remote fault exists (the fault has cleared by the time the bits are set). | Auto-negotiation is invoked immediately when a failure is detected. In the absence of character synchronization, the state machine remains in the an_enable state, which fixes the configuration register information at all zeros. | Continue auto-negotiation until it completes successfully. The link is considered failed until auto-negotiation is complete. | +| All 10G PHYs (clauses 46.3.4 and 66.3 of [IEEE 802.3]) | Remote fault is indicated continuously via an ordered set. | The receive reconciliation sub-layer detects a local fault. | Send idle on the link. | + +**Table VI.2 – Ethernet PHY local defect signals** + +| PHY | local defect | Inserted when... | Response when received (per [IEEE 802.3]) | +|--------------------------------------------------------|-----------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1000Base-X (clause 37.2.1.5 of [IEEE 802.3]) | Offline can be communicated via auto-negotiation. | When a management action causes the link to be administratively out of service, the link can be renegotiated with the offline signal included. Having sent this indication, the local end can then take the link out of service without waiting for auto-negotiation to complete. | No direct response to receiving offline, but the link will be considered failed until auto-negotiation completes successfully and the offline status will be set in the status register. | +| All 10G PHYs (clauses 46.3.4 and 66.3 of [IEEE 802.3]) | Local fault is indicated continuously via an ordered set. | A local fault in the transmitter is detected. | Generate remote fault. | + +# Appendix VII + +## Ethernet throughput of ODUflex for GFP-F mapped client signals + +(This appendix does not form an integral part of this Recommendation.) + +While the normal application of ODUflex for GFP-F mapped client signals is to provide a sub-rate or VLAN service, it is instructive to examine the Ethernet packet throughput available for various ODUflex sizes. + +The sizes of ODUflex for various tributary slot sizes are shown in Table VII.1. + +**Table VII.1 – ODUflex(GFP) capacity per tributary slot** + +| | ODUflex(GFP)
capacity | OPUflex(GFP)
capacity | +|----------------------------------------------------------|----------------------------------|----------------------------------| +| ODUflex(GFP) of $n$ tributary slots, $1 \leq n \leq 8$ | $n \times 1\,249\,177.230$ | $n \times 1\,243\,950.547$ | +| ODUflex(GFP) of $n$ tributary slots, $9 \leq n \leq 32$ | $n \times 1\,254\,470.354$ | $n \times 1\,249\,221.524$ | +| ODUflex(GFP) of $n$ tributary slots, $33 \leq n \leq 80$ | $n \times 1\,301\,467.133$ | $n \times 1\,296\,021.664$ | + +Figure VII.1 indicates packet data throughput against packet size for ODUflex(GFP) as well as Ethernet PHYs (1000BASE-X, 10GBASE-R). + +![Line graph showing MAC-Bit rate [kbit/s] vs MAC-Size [Byte] for various network configurations. The y-axis ranges from 750'000 to 10'250'000 kbit/s in increments of 250'000. The x-axis ranges from 0 to 2'048 bytes. The graph shows that throughput increases with MAC-Size and plateaus as size increases. Higher ODU levels and higher 'n' values for ODUflex(GFP) correspond to higher bit rates.](795f43a3b6469179db3a5670f31388b5_img.jpg) + +The graph illustrates the MAC-Bit rate (kbit/s) as a function of MAC-Size (Byte) for several network configurations. The configurations shown in the legend are: + +- ODU2 / GFP (light green line with circles) +- ODUflex(GFP), n = 8 (orange line with circles) +- 10GBase-R (darker orange line with crosses) +- ODUflex(GFP), n = 7 (pale green line with circles) +- ODUflex(GFP), n = 6 (pink line with crosses) +- ODUflex(GFP), n = 5 (light blue line with crosses) +- ODUflex(GFP), n = 4 (orange line with triangles) +- ODUflex(GFP), n = 3 (teal line with squares) +- ODU1 / GFP (light blue line with diamonds) +- ODUflex(GFP), n = 2 (purple line with diamonds) +- ODUflex(GFP), n = 1 (blue line with circles) +- ODU0 / GFP (light grey line with diamonds) +- 100Base-X (red line with diamonds) + +| Configuration | 64 B | 512 B | 1024 B | 2048 B | +|-------------------|------------|------------|------------|-------------| +| ODU2 / GFP | ~8,000,000 | ~9,800,000 | ~9,950,000 | ~10,000,000 | +| ODUflex(GFP), n=8 | ~8,000,000 | ~9,750,000 | ~9,900,000 | ~9,950,000 | +| 10GBase-R | ~7,500,000 | ~9,600,000 | ~9,850,000 | ~9,900,000 | +| ODUflex(GFP), n=7 | ~7,000,000 | ~8,550,000 | ~8,650,000 | ~8,700,000 | +| ODUflex(GFP), n=6 | ~6,000,000 | ~7,350,000 | ~7,450,000 | ~7,500,000 | +| ODUflex(GFP), n=5 | ~5,000,000 | ~6,100,000 | ~6,200,000 | ~6,250,000 | +| ODUflex(GFP), n=4 | ~4,000,000 | ~4,900,000 | ~4,950,000 | ~5,000,000 | +| ODUflex(GFP), n=3 | ~3,000,000 | ~3,650,000 | ~3,700,000 | ~3,750,000 | +| ODU1 / GFP | ~2,000,000 | ~2,450,000 | ~2,480,000 | ~2,500,000 | +| ODUflex(GFP), n=2 | ~2,000,000 | ~2,420,000 | ~2,450,000 | ~2,480,000 | +| ODUflex(GFP), n=1 | ~1,000,000 | ~1,220,000 | ~1,240,000 | ~1,250,000 | +| ODU0 / GFP | ~1,000,000 | ~1,210,000 | ~1,230,000 | ~1,240,000 | +| 100Base-X | ~800,000 | ~950,000 | ~980,000 | ~1,000,000 | + +G.7041-Y.1303(16)\_FVII.1 + +Line graph showing MAC-Bit rate [kbit/s] vs MAC-Size [Byte] for various network configurations. The y-axis ranges from 750'000 to 10'250'000 kbit/s in increments of 250'000. The x-axis ranges from 0 to 2'048 bytes. The graph shows that throughput increases with MAC-Size and plateaus as size increases. Higher ODU levels and higher 'n' values for ODUflex(GFP) correspond to higher bit rates. + +**Figure VII.1 – Packet data throughput for ODUflex(GFP), $n = 1, …, 8$ , ODU $k$ ( $k = 0, 1, 2$ ), 1000Base-X, 10GBase-R** + +# Bibliography + +- [b-ITU-T G.823] Recommendation ITU-T G.823 (2000), *The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy.* +- [b-ITU-T V.41] Recommendation ITU-T V.41 (1988), *Code-independent error-control system.* +- [b-ITU-T G-Sup.43] Supplement ITU-T G-Sup.43 (2011), *Transport of IEEE 10GBASE-R in optical transport networks (OTN).* + + + +# ITU-T Y-SERIES RECOMMENDATIONS + +# **GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES** + +| | | +|--------------------------------------------------------------------|----------------------| +| GLOBAL INFORMATION INFRASTRUCTURE | | +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | +| INTERNET PROTOCOL ASPECTS | | +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | +| IPTV over NGN | Y.1900–Y.1999 | +| NEXT GENERATION NETWORKS | | +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Enhancements to NGN | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Network control architectures and protocols | Y.2500–Y.2599 | +| Packet-based Networks | Y.2600–Y.2699 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | +| Carrier grade open environment | Y.2900–Y.2999 | +| FUTURE NETWORKS | | +| | Y.3000–Y.3499 | +| CLOUD COMPUTING | | +| | Y.3500–Y.3999 | +| INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES | | +| General | Y.4000–Y.4049 | +| Definitions and terminologies | Y.4050–Y.4099 | +| Requirements and use cases | Y.4100–Y.4249 | +| Infrastructure, connectivity and networks | Y.4250–Y.4399 | +| Frameworks, architectures and protocols | Y.4400–Y.4549 | +| Services, applications, computation and data processing | Y.4550–Y.4699 | +| Management, control and performance | Y.4700–Y.4799 | +| Identification and security | Y.4800–Y.4899 | +| Evaluation and assessment | Y.4900–Y.4999 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and 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+# **ITU-T G.709.1 (03/2024)** + +SERIES G: Transmission systems and media, digital systems and networks + +Digital terminal equipments – General + +--- + +## **Flexible OTN common elements** + +![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white. + +ITU logo + +# ITU-T G-SERIES RECOMMENDATIONS + +## Transmission systems and media, digital systems and networks + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100-G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200-G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300-G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400-G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450-G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600-G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700-G.799 | +| General | G.700-G.709 | +| Coding of voice and audio signals | G.710-G.729 | +| Principal characteristics of primary multiplex equipment | G.730-G.739 | +| Principal characteristics of second order multiplex equipment | G.740-G.749 | +| Principal characteristics of higher order multiplex equipment | G.750-G.759 | +| Principal characteristics of transcoder and digital multiplication equipment | G.760-G.769 | +| Operations, administration and maintenance features of transmission equipment | G.770-G.779 | +| Principal characteristics of multiplexing equipment for the synchronous digital hierarchy | G.780-G.789 | +| Other terminal equipment | G.790-G.799 | +| DIGITAL NETWORKS | G.800-G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900-G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000-G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000-G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000-G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000-G.8999 | +| ACCESS NETWORKS | G.9000-G.9999 | + +For further details, please refer to the list of ITU-T Recommendations. + +# Recommendation ITU-T G.709.1 + +## Flexible OTN common elements + +# Summary + +Recommendation ITU-T G.709.1 specifies common elements and signal structures used by various types of flexible optical transport network (FlexO) interfaces. + +Edition 3.0 removes short-reach interfaces which are moved to Recommendation ITU-T G.709.5. This Recommendation is renamed and focuses on common FlexO elements. + +## History \* + +| Edition | Recommendation | Approval | Study Group | Unique ID | +|---------|--------------------------------------|------------|-------------|--------------------| +| 1.0 | ITU-T G.709.1/Y.1331.1 | 2017-01-12 | 15 | 11.1002/1000/13082 | +| 2.0 | ITU-T G.709.1/Y.1331.1 | 2018-06-22 | 15 | 11.1002/1000/13521 | +| 2.1 | ITU-T G.709.1/Y.1331.1 (2018) Amd. 1 | 2019-04-06 | 15 | 11.1002/1000/13743 | +| 2.2 | ITU-T G.709.1/Y.1331.1 (2018) Cor. 1 | 2020-05-07 | 15 | 11.1002/1000/14200 | +| 2.3 | ITU-T G.709.1/Y.1331.1 (2018) Amd. 2 | 2020-12-22 | 15 | 11.1002/1000/14519 | +| 2.4 | ITU-T G.709.1/Y.1331.1 (2018) Amd. 3 | 2022-11-13 | 15 | 11.1002/1000/15135 | +| 2.5 | ITU-T G.709.1/Y.1331.1 (2018) Amd. 4 | 2023-08-22 | 15 | 11.1002/1000/15561 | +| 3.0 | ITU-T G.709.1 | 2024-03-08 | 15 | 11.1002/1000/15810 | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2024 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------------|--------------------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 3 | +| 5 | Conventions ..... | 5 | +| 6 | Introduction and applications ..... | 5 | +| 6.1 | Short-reach FlexO interfaces ..... | 6 | +| 6.2 | Long-reach FlexO interfaces ..... | 6 | +| 7 | Structure and processes..... | 6 | +| 7.1 | Basic signal structure..... | 6 | +| 7.2 | Processing and information flow ..... | 7 | +| 8 | FlexO frame and maintenance ..... | 7 | +| 8.1 | Frame structure ..... | 7 | +| 8.2 | Multi-frame structure..... | 8 | +| 8.3 | Bit rates and frame periods..... | 8 | +| 8.4 | FlexO-x(e) frame structure ..... | 9 | +| 8.5 | FlexO maintenance ..... | 9 | +| 9 | Overhead..... | 10 | +| 9.1 | Alignment mechanism..... | 10 | +| 9.2 | Basic overhead (BOH) description..... | 11 | +| 9.3 | Extended overhead (EOH) description..... | 17 | +| 10 | FlexO mapping procedures..... | 23 | +| 10.1 | BMP mapping of OTUCn client into FlexO-n ..... | 23 | +| 10.2 | GMP mapping of Ethernet clients into FlexO-ne..... | 26 | +| 10.3 | GMP mapping of OTUCn clients into FlexO-n ..... | 33 | +| 10.4 | FlexO-n group alignment and deskewing..... | 38 | +| 10.5 | FlexO payload PRBS test pattern ..... | 38 | +| Annex A | – FlexOsec encryption and authentication ..... | 40 | +| A.1 | GCM-AES-256 frame payload encryption..... | 40 | +| Annex B | – Applying generic mapping procedure principles in a FlexO-n(e)..... | 45 | +| B.1 | Applying GMP in a FlexO-n(e)..... | 45 | +| Annex C | – Transporting Ethernet client and Regen Local Degrade and Remote Degrade..... | 50 | +| C.1 | Ethernet client CSTAT LD/RD ..... | 50 | +| C.2 | Ethernet client CSTAT and Regen RSTAT LD/RD ..... | 52 | +| Appendix I | – Example short-reach applications ..... | 53 | + +| | | +|----------------------------------------------------|----| +| Appendix II – Example long-reach applications..... | 55 | +| Bibliography..... | 58 | + +# Recommendation ITU-T G.709.1 + +## Flexible OTN common elements + +# 1 Scope + +This Recommendation specifies common elements and signal structures used by various types of flexible optical transport network (FlexO) interfaces, both for single vendor applications and multi-vendor interoperable applications. Such definitions include FlexO frame, FlexO instance interleaving, mapping procedures to FlexO-n(e) and FlexO overhead. FlexO interfaces support bonding (i.e., grouping) of multiple interfaces such that one or more client signals (e.g., OTUCn or Ethernet) can be transferred via one or more optical tributary signals (OTSi) over one or more physical interfaces. Interoperable short-reach and long-reach interfaces are defined in other Recommendations such as [ITU-T G.709.3], [ITU-T G.709.5] and [ITU-T G.709.6]. + +In addition, some introduction material for the various short and long-reach applications is included. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.698.2] Recommendation ITU-T G.698.2 (2018), *Amplified multichannel dense wavelength division multiplexing applications with single channel optical interfaces*. +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2020), *Interfaces for the optical transport network*. +- [ITU-T G.709.3] Recommendation ITU-T G.709.3 (2024), *Flexible OTN B100G long-reach interfaces*. +- [ITU-T G.709.5] Recommendation ITU-T G.709.5 (2024), *Flexible OTN short-reach interfaces*. +- [ITU-T G.709.6] Recommendation ITU-T G.709.6 (2024), *Flexible OTN B400G long-reach interfaces*. +- [ITU-T G.798] Recommendation ITU-T G.798 (2023), *Characteristics of optical transport network hierarchy equipment functional blocks*. +- [ITU-T G.872] Recommendation ITU-T G.872 (2024), *Architecture of the optical transport network*. +- [ITU-T G.959.1] Recommendation ITU-T G.959.1 (2024), *Optical transport network physical layer interfaces*. +- [ITU-T G.7041] Recommendation ITU-T G.7041/Y.1303 (2016), *Generic framing procedure*. +- [ITU-T G.8260] Recommendation ITU-T G.8260 (2022), *Definitions and terminology for synchronization in packet networks*. +- [IEEE 802.3] IEEE Std. 802.3-2022, *IEEE Standard for Ethernet*. + +- [IEEE 802.3df] IEEE Std. 802.3df-2023, *IEEE Standard for Ethernet Amendment 9: Media Access Control Parameters for 800 Gb/s and Physical Layers and Management Parameters for 400 Gb/s and 800 Gb/s Operation* +- [NIST SP 800-38D] National Institute of Standards and Technology (2007), *Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC*. +- [OIF FlexE] Optical Interworking Forum, OIF (2021), *FlexEthernet Implementation Agreement 2.2*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +### 3.1.1 Terms defined in [ITU-T G.709]: + +- completely standardized OTUCn (OTUCn) +- optical transport network (OTN) + +**3.1.2 cipher text** [b-ITU-T X.800]: Data produced through the use of encipherment. The semantic content of the resulting data is not available. + +**3.1.3 confidentiality** [b-ITU-T X.800]: The property that information is not made available or disclosed to unauthorized individuals, entities, or processes. + +**3.1.4 encryption** [b-ITU-T X.800]: The cryptographic transformation of data to produce ciphertext. + +**3.1.5 integrity** [b-ITU-T X.800]: The property that data has not been altered or destroyed in an unauthorized manner. + +**3.1.6 key** [b-ITU-T X.800]: A sequence of symbols that controls the operations of encipherment and decipherment. + +**3.1.7 plaintext** [b-ISO/IEC 18033-3]: Unenciphered information. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 FlexO**: Information structure with a specific bit rate and frame format, consisting of overhead and payload, intended to be used in a group. + +**3.2.2 FlexO-n**: Information structure consisting of a group of $n$ ( $n \geq 1$ ) FlexO instances for the transport of OTUCn and Ethernet clients. + +**3.2.3 FlexO-x**: Information structure consisting of $x$ ( $x \geq 1$ ) interleaved FlexO instances, intended to be used in a group with $m$ ( $m = \lceil n/x \rceil$ ) instances for the transport of client signals such as OTUCn or Ethernet. The order $x$ signifies the FlexO-x interface rate in units of 100G. + +**3.2.4 FlexO-x-**: Information structure consisting of a FlexO-x plus FEC parity and possibly DSP framing. In some instances, name indicates modulation type. + +**3.2.5 FlexO-x- interface**: Refers to an individual member interface that is part of a FlexO-x--m interface group. + +NOTE – The terms "member" and "PHY" are often used to refer to a FlexO-x- interface. + +**3.2.6 FlexO-x--m interface group**: Refers to the group of $m \times$ FlexO-x- interfaces. + +NOTE – The text may use "FlexO group" as short-hand for FlexO-x--m interface group. + +**3.2.7 FOICx.k-**: Refers to a FlexO-x- interface using k parallel lanes. + +NOTE – "FOICx.k" is the FlexO equivalent of "OTLk.m" for OTUk as defined in [ITU-T G.709]. + +# **4 Abbreviations and acronyms** + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-----------------|-------------------------------------------------------------------| +| AAD | Additional Authenticated Data | +| AIS | Alarm Indication Signal | +| AM i | Alignment Marker of index i | +| AM | Alignment Mechanism | +| AT | Authentication Tag | +| B100G | Beyond 100G | +| B400G | Beyond 400G | +| BIP | Bit Interleaved Parity | +| BMP | Bit-synchronous Mapping Procedure | +| BOH | Basic Overhead Field | +| CFP2 | C (100G) Form-factor Pluggable Optical Module, form factor type 2 | +| CRC | Cyclic Redundancy Check | +| CSF | Client Signal Fail | +| CST | Cipher Suite Type | +| CSTAT | Client status | +| EOH | Extended Overhead Field | +| FA | Frame Alignment | +| FAS | Frame Alignment Signal | +| FBA | FEC Block Alignment | +| FCC0/1 | FlexO Communications Channel 0 or 1 | +| FEC | Forward Error Correction | +| FlexE | Flexible Ethernet | +| FlexO | Flexible Optical Transport Network | +| FN | Frame Number | +| FS | Fixed Stuff | +| GFP | Generic Framing Procedure | +| GID | Group Identification | +| GMP | Generic Mapping Procedure | +| IA | Implementation Agreement | +| IID | FlexO Instance Identification | +| IV | Initialization Vector | +| KCC | Key exchange Communication Channel | + +| | | +|--------|---------------------------------------------------| +| KI | Key Index | +| LCK | Locked | +| LD | Local Degrade | +| LF | Local Fault | +| LSB | Least Significant Bit | +| MAP | FlexO Map field | +| MDI | Media Dependent Interface | +| MFAS | Multi-Frame Alignment Signal | +| MNT | Maintenance | +| MS | Multiplexed Section | +| MSB | Most Significant Bit | +| ODU | Optical Data Unit | +| OFEC | Open FEC | +| OH | Overhead | +| OPU | Optical Payload Unit | +| OSMC | OTN Synchronization Messaging Channel | +| OTL | Optical Transport Lane | +| OTN | Optical Transport Network | +| OTSi | Optical Tributary Signal | +| OTU | Optical Transport Unit | +| OTUCn | OTU order Cn | +| PCS | Physical Coding Sublayer | +| PHY | Physical Layer | +| PRBS | Pseudo Random Binary Sequence | +| PT | Payload type | +| PTP | Precision Time Protocol | +| QSFP28 | Quad (100G) Small Form-factor Pluggable | +| RD | Remote degrade | +| RES | Reserved for Future International Standardization | +| RPF | Remote Physical Layer Fault | +| RS | Reed-Solomon | +| RSTAT | Regen Status | +| SSM | Synchronization Status Message | +| STAT | FlexO Status | +| RTTI | Regen Trail Trace Identifier | +| WDM | Wavelength Division Multiplexing | + +# 5 Conventions + +This Recommendation uses the following conventions: + +## Names of information structures and interfaces + +The terms FlexO-n, FlexO-x, FlexO-x-, FlexO-x--m, and FOICx.k- are used to refer to FlexO information structures and interfaces that are optimized for OTN bit rates. + +**n:** The index "n" is used to represent the number of FlexO instances that are in a FlexO group. + +**x:** The index "x" is used to represent the bit rate of the FlexO interface, in 100G increments. For example, x=1 for 100G, x=2 for 200G, x=4 for 400G, etc. + +**(e):** When used as FlexO-x(e), it is short-hand for "or" (e.g., FlexO-x or FlexO-xe), with the "e" meaning optimized for Ethernet payloads. Same short-hand concept is used for FlexO-n(e). + +**m:** The index "m" is used to represent the number of interfaces in a FlexO group. m is also used to represent the number of bits in a block of data/stuff in client mappings. + +**k:** The index "k" is used to represent the number of lanes on an FOICx.k- interface. + +**:** The placeholder is used by specific short-reach and long-reach interface Recommendations to provide a unique name to the interface. The interface can be identified by a FEC type or a combination of FEC type and modulation type. + +**Transmission order:** The order of transmission of information in all the diagrams in this Recommendation is first from left to right and then from top to bottom. Within each byte the most significant bit is transmitted first. The most significant bit (bit 1) is illustrated on the left side of all diagrams. + +**Value of reserved bit(s):** The value of an overhead bit, which is reserved for future international standardization, shall be set to "0". + +**Value of non-sourced bit(s):** Unless stated otherwise, any non-sourced bits shall be set to "0". + +# 6 Introduction and applications + +Flexible optical transport network (FlexO) interface groups (FlexO-x(e)--m) are defined for a variety of applications. They complement [ITU-T G.709], by providing interfaces for OTUCn transport as well as interfaces for Ethernet optimized transport. A FlexO-x--m interface group provides modularity by bonding standard-rate interfaces (e.g., 100G and 400G), over which the OTUCn clients are adapted and multiplexed. A FlexO-xe--m interface group is optimized for adapting and multiplexing Ethernet clients. + +A FlexO-x(e)--m interface provides FEC, scrambling, bit alignment as well as operational, administrative and maintenance overhead. Common elements of the information structure (e.g., FlexO-x) can be leveraged for functionally standardized single vendor interfaces. Fully standardized multi-vendor interoperable interfaces are also defined in companion FlexO Recommendations for both short-reach and long-reach applications. + +FlexO instance rates are designed to support reuse of 100G pluggable modules that also support OTU4 as specified in [ITU-T G.709]. + +A FlexO-x(e)--m interface group: + +- provides an interoperable system OTN interface; +- enables higher capacity clients (e.g., ODUflex and OTUCn), by means of bonding m interfaces in a group; +- provides a FEC tailored for the application; +- provides optional encryption at the FlexO layer; + +- provides interface rate modularity and flexibility; +- provides a frame, alignment, deskew, group management, management communication channel and such functions that are not associated with the client signal; +- enables regeneration applications. + +## 6.1 Short-reach FlexO interfaces + +Short-reach interfaces are specified in [ITU-T G.709.5] using a Reed-Solomon forward error correction or RS FEC typical of similar Ethernet interfaces and are intended to support multi-vendor interoperable connectivity. Short-reach interfaces are often supported on direct detect multi-lane modules such as QSFP28, QSFPDD, OSFP and CFP2. Short-reach interfaces only support OTUCn clients, and do not include Ethernet optimized variants. + +NOTE – The logical signal format of FlexO short-reach interface (FOICx.k-RS) can be reused on a system internal interface (interoperable component-to-component interface) specified in [b-ITU-T G-Sup.58]. + +Example applications are provided in Appendix I. + +## 6.2 Long-reach FlexO interfaces + +Long-reach applications can be both single vendor and multi-vendor interoperable. The multi-vendor long-reach FlexO interfaces are fully specified in [ITU-T G.709.3] for B100G rates of 100G-400G (FlexO-x with x =1, 2 and 4) and [ITU-T G.709.6] for B400G rates of 400G-800G (FlexO-x with x =4 and 8). In order to mitigate the impairments of accumulated noise, these interfaces use forward error correction (FEC) schemes with a higher coding gain than the FEC type deployed in FlexO short-reach interfaces. Long-reach FlexO interfaces are typically used with wavelength division multiplexing (WDM) and are based on coherent detection. + +Example applications are shown in Appendix II. + +# 7 Structure and processes + +This clause introduces the functions associated with a FlexO-x(e)--m interface group and the basic signal structure, processes and atomic functions associated with the common FlexO elements across different types of interfaces. + +## 7.1 Basic signal structure + +The FlexO-x(e)--m interface group architecture is specified in [ITU-T G.872]. The information structure for FlexO-x(e)--m interface group is represented by information containment relationships and flows. + +The principal information containment relationship for a FlexO-x(e)--m group interface is described in Figure 7-1. One or many client signals (OTUCn or Ethernet) are mapped into a FlexO-n(e) signal. The n FlexO instances from the FlexO-n(e) signal are mapped into m (m ≤ n) FlexO-x- interfaces. Each FlexO-x- interface contains one or more FlexO instances from the FlexO-n(e) signal. Finally, forward error correction (FEC) adaptation consists of adding FEC parity bits, and appropriate padding. The details of FEC adaptation are beyond the scope of this Recommendation. + +In scenarios involving mapping of FlexO-n(e) into a FlexO-x(e)--m group interface and $n < (m \times x)$ , some instances are marked unequipped as described in clause 10. + +![Diagram illustrating the principal information containment relationship for FlexO-x(e). It shows the hierarchy from Client (1 or more clients) down to FlexO-n(e), then m FlexO-x(e) interfaces, and finally FlexO-x(e)--m interfaces. Each level shows the payload and overhead (Alignment OH, EOH, BOH) structure. The diagram also indicates that FlexO instances are interleaved and FEC adapted. A legend defines the overhead types: Alignment OH (hatched), EOH (dotted), and BOH (cross-hatched).](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Client + +1 or more clients + +FlexO-n(e) + +n +2 +1 + +Payload + +m FlexO-x(e) + +$m = \lceil n/x \rceil$ + +m +2 +1 + +Payload + +FlexO-x(e)--m + +$m = \lceil n/x \rceil$ + +m +2 +1 + +Payload + ++ FEC + +*FlexO instances (OH and payload) interleaved and FEC adapted* + +Legend: + +- Alignment OH (hatched) +- EOH (dotted) +- BOH (cross-hatched) + +G.709.1(24) + +Diagram illustrating the principal information containment relationship for FlexO-x(e). It shows the hierarchy from Client (1 or more clients) down to FlexO-n(e), then m FlexO-x(e) interfaces, and finally FlexO-x(e)--m interfaces. Each level shows the payload and overhead (Alignment OH, EOH, BOH) structure. The diagram also indicates that FlexO instances are interleaved and FEC adapted. A legend defines the overhead types: Alignment OH (hatched), EOH (dotted), and BOH (cross-hatched). + +**Figure 7-1 – FlexO-x(e) principal information containment relationship** + +## 7.2 Processing and information flow + +Functions, processes and information flows are more formally specified in [ITU-T G.798]. + +# 8 FlexO frame and maintenance + +A FlexO frame is associated with a FlexO-x(e)- interface and is independent of client structures carried within the FlexO payload. A FlexO frame structure can be used for FlexO-x or Ethernet optimized FlexO-xe interfaces. + +A FlexO frame consists of a frame alignment mechanism field (AM), extended overhead field (EOH), basic overhead field (BOH) and payload area. + +The FlexO frames carried over m interfaces of a FlexO-x(e)--m interface group are frame/multi-frame aligned at the source. + +## 8.1 Frame structure + +The FlexO frame structure is shown in Figure 8-1 and consists of 128 rows by 5,140 1-bit columns. It contains a frame alignment mechanism field (AM) in row 1, columns 1 to 480, an extended overhead field (EOH) in row 1, columns 481 to 960, a basic overhead field (BOH) in row 1 columns 961 to 1280 and a $(128 \times 5140 - 1280 = 656640 \text{ bit})$ payload area in the remainder of the frame. + +NOTE – The FlexO frame structure is derived from 100Gbit/s Ethernet clause 91 [IEEE 802.3] FEC alignment and lane architecture, without any 66b alignment or 256b/257b transcoding functions. + +![Figure 8-1 – FlexO frame structure diagram showing a grid of 128 rows and 5140 columns. The first row contains AM (columns 1-480), EOH (columns 481-960), and BOH (columns 961-1280). The remaining columns (1281-5140) in all rows are labeled 'Payload'. A double-headed arrow at the bottom indicates the total width is 5140 bits. Reference G.709.1-Y.1331.1(18)-Amd.2(20)_F8-1 is noted.](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +Figure 8-1 – FlexO frame structure diagram showing a grid of 128 rows and 5140 columns. The first row contains AM (columns 1-480), EOH (columns 481-960), and BOH (columns 961-1280). The remaining columns (1281-5140) in all rows are labeled 'Payload'. A double-headed arrow at the bottom indicates the total width is 5140 bits. Reference G.709.1-Y.1331.1(18)-Amd.2(20)\_F8-1 is noted. + +**Figure 8-1 – FlexO frame structure** + +## 8.2 Multi-frame structure + +In order to provide space for additional OH fields, an 8-frame FlexO multi-frame structure is defined. It uses the three least significant bits of the multi-frame alignment signal (MFAS) overhead to identify the eight frames within the multi-frame. + +The multi-frame payload structure details are defined in clause 10. + +## 8.3 Bit rates and frame periods + +The bit rates and tolerances of the FlexO signal interfaces are defined in Table 8-1. + +**Table 8-1 – FlexO-n(e) bit rates** + +| Interface Type | FlexO-n(e) nominal bit rate | FlexO-n(e) bit-rate tolerance | +|----------------|----------------------------------------------------------|-------------------------------| +| FlexO-n | $n \times 491384/462961 \times 99\,532\,800$ kbit/s | $\pm 20$ ppm | +| FlexO-ne | $n \times 21845/25984 \times 766 \times 156\,250$ kbit/s | $\pm 20$ ppm | + +NOTE 1 – The nominal FlexO-n bit rate is approximately: $n \times 105\,643\,510.782$ kbit/s. The FlexO-n bit rate can be derived from the OTUC bit rate as follows: $4112/4097 \times n \times \text{OTUC bit rate} = 4112/4097 \times 239/226 \times n \times 99\,532\,800$ kbit/s. + +NOTE 2 – The nominal FlexO-ne bit rate is approximately: $n \times 100\,622\,438.327$ kbit/s. The FlexO-ne bit rate can be derived from 156M Ethernet clock multiple as follows: $n \times 514/544 \times 1445/1624 \times 766 \times 156\,250$ kbit/s. + +The frame and multi-frame periods of the FlexO signal interfaces are defined in Table 8-2. + +**Table 8-2 – FlexO-n(e) frame and multi-frame periods** + +| Interface Type | Frame period (Note) | 8-frame multi-frame period (Note) | 4-frame multi-frame period (Note) | +|----------------|---------------------------|-----------------------------------|-----------------------------------| +| FlexO-n | $\sim 6.228\ \mu\text{s}$ | $49.822\ \mu\text{s}$ | $24.911\ \mu\text{s}$ | +| FlexO-ne | $\sim 6.539\ \mu\text{s}$ | $52.310\ \mu\text{s}$ | $26.155\ \mu\text{s}$ | + +NOTE – The period is an approximated value, rounded to 3 decimal places. + +FlexO maintenance signals such as alarm indication signal (AIS) and locked (LCK), are generated using a local clock. + +## 8.4 FlexO-x(e) frame structure + +This section defines generic z-bit interleaving for FlexO-x(e)- interfaces with $x > 1$ . The value of z is interface specific and defined by [ITU-T G.709.3], [ITU-T G.709.5] and [ITU-T G.709.6]. + +The FlexO-1(e) frame structure is equal to the FlexO instance frame structure as shown in Figure 8-1. + +The FlexO-x(e) frame structure is shown in Figure 8-2 and consists of $x \times 64$ rows by 10280 1-bit columns. The x FlexO instances are z-bit interleaved into the FlexO-x(e) frame in order from lowest identification (IID) to highest IID. + +![Figure 8-2 – FlexO-x(e) frame structure diagram showing the interleaving of multiple FlexO instances into a single frame.](75f0cb39f1cd165dfe4a6aa6c4d9388d_img.jpg) + +The diagram illustrates the frame structure for FlexO-x(e). At the top, three individual FlexO instances are shown as red, green, and yellow rectangles, labeled FlexO #1 (lowest IID), FlexO #2, and FlexO #x (highest IID). Each instance has 128 rows and 5140 columns. The first 1280 columns are divided into three overhead fields: AM (columns 1-480), EOH (columns 481-960), and BOH (columns 961-1280). The remaining 3860 columns (1281-5140) form the 'Payload area'. Below these, a dashed line indicates the interleaving process. The bottom part shows the resulting FlexO-x(e) frame, which has $x \times 64$ rows and 10280 columns. Each row contains a small segment of data from each of the x instances, z-bit interleaved. The first 480 columns are labeled 'AM' and contain the interleaved overhead. The remaining 9800 columns (481-10280) form the interleaved payload area. A small detail at the bottom right shows a single row with colored blocks representing the interleaved data from different instances. + +Figure 8-2 – FlexO-x(e) frame structure diagram showing the interleaving of multiple FlexO instances into a single frame. + +Figure 8-2 – FlexO-x(e) frame structure + +## 8.5 FlexO maintenance + +FlexO maintenance states are indicated in the maintenance (MTN) field of the STAT overhead as described in clause 9.2.3.3. + +LCK and AIS definitions and behaviour are the same as [ITU-T G.709]. An alarm indication signal (AIS) is a signal sent downstream as an indication that an upstream defect has been detected. An AIS signal is generated in an adaptation sink function. An AIS signal is detected in a trail termination sink function to suppress defects or failures that would otherwise be detected as a consequence of the interruption of the transport of the original signal at an upstream point. A locked (LCK) is a signal sent downstream as an indication that upstream the connection is "locked", and no signal has passed through. An LCK signal is generated in an adaptation source or sink function. An LCK signal is detected in a trail termination sink function. + +LCK is specified as a repeating "0101 0101" pattern and AIS is specified as a repeating "1111 1111" in the entire FlexO payload, BOH, EOH and AM as shown in Figure 8-3. + +![Figure 8-3: FlexO AIS/LCK squelch diagram. A grid showing Columns (1 to 5140) and Rows (1 to 128). Row 1 contains AM, EOH, and BOH fields. Rows 2 through 64 are labeled 'Repeating pattern'. Rows 65 through 128 are empty. The diagram is labeled G.709.1(24).](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Figure 8-3: FlexO AIS/LCK squelch diagram. A grid showing Columns (1 to 5140) and Rows (1 to 128). Row 1 contains AM, EOH, and BOH fields. Rows 2 through 64 are labeled 'Repeating pattern'. Rows 65 through 128 are empty. The diagram is labeled G.709.1(24). + +Figure 8-3 – FlexO AIS/LCK squelch + +Before they are presented at the optical transport network (OTN) interface, the LCK and AIS FlexO signals are extended with AM, the MFAS and cyclic redundancy check (CRC) fields from the BOH, and may also get extended by regenerator fields from EOH and FCC1 field from BOH. This is dependent on the functionality between the LCK and AIS insertion points, and the OTN interface. The presence of LCK and AIS is detected by monitoring the MNT bits in the STAT overhead field. + +# 9 Overhead + +The FlexO frame overhead consists of alignment mechanism field (AM), basic overhead (BOH) and extended overhead (EOH). FlexO total overhead fields in an elementary FlexO frame consist of 1,280 bits per FlexO instance, 480 bits for AM, 480 bits for EOH and 320 bits for BOH. + +The aggregate frame of a higher rate FlexO-x(e)- interface is constructed by interleaving multiple FlexO frame instances. + +An overview of FlexO frame overhead areas is presented in Figure 9-1. + +![Figure 9-1: Overhead overview diagram. A grid showing Columns (1 to 5140) and Rows (1 to 128). The grid is divided into four main columns: FlexOfec, Regen, FlexOsec, and RES. The first column, FlexOfec, is further divided into sub-columns: AM, EOH, BOH, MFAS, STAT, GID, RES, IID, MAP, CRC, FCC1/RES, and OSMC/RES. The diagram shows the mapping of overhead fields across multiple frames (Frame 1 and Frame 2) and includes a legend for the overhead fields.](cb4cfa42ce34febde7bdb882f3fc3094_img.jpg) + +| Columns | FlexOfec | | | | | | | | | | | | Regen | | | | FlexOsec | | | | RES | | | | +|---------|----------|-----|-----|------|------|-------|-----|-----|-----|-----|----------|----------|-------|--|--|--|----------|--|--|--|-----|--|--|--| +| Rows | AM | EOH | BOH | MFAS | STAT | GID | RES | IID | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 1 | | | | MFAS | STAT | AVAIL | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 2 | | | | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 64 | | | | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 65 | | | | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 128 | | | | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 1 | AM | EOH | BOH | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 65 | | | | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | +| 128 | | | | MFAS | STAT | | | | MAP | CRC | FCC1/RES | OSMC/RES | | | | | | | | | | | | | + +Legend: + +- MFAS: Multi-frame alignment +- STAT: Status +- GID: Group identification +- IID: Instance identification +- AVAIL: OTUC availability +- PT: Payload type +- RES: Reserved/unused +- MAP: PHY/member map +- CRC: Cyclic redundancy check +- FCC1: FlexO communications channel +- OSMC: OTN synchronization message channel + +Figure 9-1: Overhead overview diagram. A grid showing Columns (1 to 5140) and Rows (1 to 128). The grid is divided into four main columns: FlexOfec, Regen, FlexOsec, and RES. The first column, FlexOfec, is further divided into sub-columns: AM, EOH, BOH, MFAS, STAT, GID, RES, IID, MAP, CRC, FCC1/RES, and OSMC/RES. The diagram shows the mapping of overhead fields across multiple frames (Frame 1 and Frame 2) and includes a legend for the overhead fields. + +Figure 9-1 – Overhead overview + +## 9.1 Alignment mechanism + +The alignment mechanism details are interface specific and outside the scope of this Recommendation. + +## 9.2 Basic overhead (BOH) description + +The FlexO BOH field is contained in the 320 bits following the FlexO frame EOH field. The BOH structure amounts to 2,560 bits (320 bytes) and is distributed across an 8-frame multi-frame, as shown in Figure 9-2. Each frame contains 40 BOH bytes. + +![](2cde062fd82833415971a8bd1a2cafab_img.jpg) + +**BOH bytes for FlexO instance #1** + +| MFAS bits | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | ..... | 26 | 27 | 28 | 29 | ..... | 40 | +|-------------|---|------|------|-------|-----|-----|-----|-----|---|-----|-----|------|------|-------|----|----|----|----|-------|----| +| [678] frame | | | | | | | | | | | | | | | | | | | | | +| 000 | 1 | MFAS | STAT | GID | GID | GID | RES | IID | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 001 | 2 | MFAS | STAT | AVAIL | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 010 | 3 | MFAS | STAT | | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 011 | 4 | MFAS | STAT | | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 100 | 5 | MFAS | STAT | | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 101 | 6 | MFAS | STAT | | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 110 | 7 | MFAS | STAT | | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | +| 111 | 8 | MFAS | STAT | | | | | | | MAP | CRC | FCC1 | OSMC | | | | | | | | + +**BOH bytes for FlexO instance #2 to #x** + +| MFAS bits | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | ..... | 26 | 27 | 28 | 29 | ..... | 40 | +|-------------|---|------|------|-------|-----|-----|-----|-----|---|-----|-----|-----|-----|-------|----|----|----|----|-------|----| +| [678] frame | | | | | | | | | | | | | | | | | | | | | +| 000 | 1 | MFAS | STAT | GID | GID | GID | RES | IID | | MAP | CRC | RES | RES | | | | | | | | +| 001 | 2 | MFAS | STAT | AVAIL | | | | | | MAP | CRC | RES | RES | | | | | | | | +| 010 | 3 | MFAS | STAT | | | | | | | MAP | CRC | RES | RES | | | | | | | | +| 011 | 4 | MFAS | STAT | | | | | | | MAP | CRC | RES | RES | | | | | | | | +| 100 | 5 | MFAS | STAT | | | | | | | MAP | CRC | RES | RES | | | | | | | | +| 101 | 6 | MFAS | STAT | | | | | | | MAP | CRC | RES | RES | | | | | | | | +| 110 | 7 | MFAS | STAT | | | | | | | MAP | CRC | RES | RES | | | | | | | | +| 111 | 8 | MFAS | STAT | | | | | | | MAP | CRC | RES | RES | | | | | | | | + +G.709.1(24) + +**Figure 9-2 – FlexO BOH structure** + +The FlexO BOH field contains the following subfields (see Figure 9-2): + +- multi-frame alignment signal (MFAS) +- status (STAT) +- group management overhead including: + - group identification (GID) + - FlexO instance identification (IID) + - FlexO map (MAP) +- payload overhead including: + - payload type (PT) + - client mapping specific + - OTUC availability (AVAIL) – defined in clause 9.2.6.1 +- cyclic redundancy check (CRC) +- FlexO management communication channel (FCC1) +- OTN synchronization message channel (OSMC) +- bits reserved for future international standardization (RES) + +### 9.2.1 Multi-frame alignment signal (MFAS) + +An 8-bit (1 byte) multi-frame alignment signal field is provided and incremented in every FlexO frame. This MFAS field counts 0x00 to 0xFF and provides a 256-frame FlexO multi-frame. + +This central multi-frame is used to lock 2-frame, 4-frame, 8-frame, 16-frame, 32-frame, etc. multi-frame structures of overhead and payload structure to the principal frame. The MFAS sequence is shown in Figure 9-3. + +![](ff7ce44f3fdd51bae7b231f34df07c6a_img.jpg) + +| | | | | | | | | +|--------------|---|---|---|---|---|---|---| +| MFAS OH byte | | | | | | | | +| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| ⋮ | | | | | | | | +| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | +| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | +| 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | +| 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | +| 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | +| ⋮ | | | | | | | | +| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | +| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | +| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | +| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | + +MFAS sequence + +G.709.1(24) + +**Figure 9-3 – Multi-frame alignment signal overhead** + +The MFAS field is located in all FlexO frames, in overhead byte 1 immediately following the AM. + +### 9.2.2 Group management overhead + +#### 9.2.2.1 Group identification (GID) + +A 20-bit (2.5 bytes) FlexO group identification (GID) field is provided to indicate the interface group instance that the FlexO-x(e)- interface is a member of. The GID provides the ability to check at the receive side that the interface belongs to the intended FlexO group. + +The GID field is located in frame 1, in overhead bytes 3, 4 and 5. + +The same FlexO group identification value is used in both directions of transport. + +Non-zero values for GID are valid and the value of "0" is reserved for this field. + +A FlexO instance is marked as unequipped with its FlexO GID value default to "0" when it does not belong to any FlexO-n group and so does not carry any client signal in its payload. A FlexO-x(e)- interface that is not part of any group carries unequipped FlexO instances. + +#### 9.2.2.2 FlexO instance identification (IID) + +A FlexO-x(e)--m interface group is composed of m FlexO-x(e)- interfaces, also referred to as members. An 8-bit (1 byte) IID field is provided to uniquely identify each FlexO instance of a group and the order of each instance and member in the group. This information is required in the reordering process. + +The IID values of the interfaces in a FlexO group are not necessarily arranged consecutively. The IID values indicate the order of the interfaces within the FlexO group, from low to high. The first FlexO-x(e)- interface in the group is the one with the lowest IID value(s). + +The FlexO instances identification value(s) (IID) within a FlexO-x(e)- interface shall all be larger than the IID value(s) within the prior FlexO-x(e)- interface in the group, and shall all be smaller than the IID value(s) within the next FlexO-x(e)- interface in the group. + +The IID field is located in frame 1, in overhead byte 6. The values "0" and "255" are reserved for this field. + +The same FlexO instance identification value is used in both directions of transport. + +#### 9.2.2.3 FlexO map (MAP) + +A 256-bit (32 bytes) field is provided to indicate the members belonging to the group. Each bit in the field, is set to "1" indicating that an instance is part of the group. The bit position of the MAP corresponds to the IID set for the member FlexO-x(e)- interface, with the most significant bit (MSB) corresponding to lowest numbered IID. The remaining unused fields in the MAP are set to "0". The full MAP is sent and received on all members of the group. + +The MAP field is located in all frames of all FlexO instances in a group, in overhead bytes 7, 8, 9 and 10. As shown in Figure 9-4, bit 2 of overhead byte 7 in frame 1 is associated with IID#1 and bit 7 of overhead byte 10 in frame 8 is associated with IID #254. Additionally, bit 1 of overhead byte 7 in frame 1, and bit 8 of overhead byte 10 in frame 8 are reserved. + +![](8fa679f79a1bb1f527cba9f29e784e89_img.jpg) + +| Frame | MAP bytes | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|-------|-----------|----|---|---|---|---|---|---|---|---|----|----|----|----|----|----|----|----|----|----|----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|---| +| | 7 | | | | | | | 8 | | | | | | | | 9 | | | | | | | | 10 | | | | | | | | | | +| 1 | RES | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | | +| 2 | 32 | 33 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | +| 3 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | +| 4 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | +| 5 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | +| 6 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | +| 7 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | +| 8 | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | 245 | 246 | 247 | 248 | 249 | 250 | 251 | 252 | 253 | 254 | RES | | + +G.709.1(24) + +Figure 9-4 – FlexO MAP field + +### 9.2.3 Status (STAT) + +An 8-bit (1 byte) field, as shown in Figure 9-5, is provided for general purpose status indication for the FlexO instance. + +- Remote fault (RF) +- Maintenance (MNT) +- Reserved (RES) + +![](40f30e4d577a17052f8b1e6dc802a0d8_img.jpg) + +| Bits | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +|------|----|-----|---|---|-----|---|---|---| +| | RF | MNT | | | RES | | | | + +G.709.1(24) + +Figure 9-5 – FlexO BOH STAT field + +The STAT field is located in all frames, in overhead byte 2 as shown in Figure 9-2. + +NOTE – Implementations developed prior to Edition 2.5 of this Recommendation do not support the MNT field, those bits are Reserved. Previous Editions also only have RPF field in the first instance, and this has been repurposed in Edition 2.5 to the RF field in all instances. + +#### 9.2.3.1 Remote fault (RF) + +For section monitoring, a single bit remote fault (RF) indication conveys the signal fail status detected at the remote FlexO sink function in the upstream direction. + +RF is set to "1" to indicate a remote fault/defect indication; otherwise, it is set to "0". + +NOTE – Editions prior to 2.5 of this Recommendation referred to this field as remote physical layer fault (RPF). + +#### 9.2.3.2 Reserved (RES) + +Four bits of the STAT byte are reserved for future international standardization as shown in Figure 9-5. These bits are set to "0". + +#### 9.2.3.3 Maintenance (MNT) + +Three bits of the STAT byte are used for signalling maintenance states. + +- 000 – Normal operation +- 111 – AIS +- 101 – LCK + +NOTE – 100 value is reserved due to FlexOsec squelch pattern. + +### 9.2.4 Payload overhead + +The FlexO payload overhead consists of: OTUC availability (AVAIL), payload type (PT) and client mapping specific overhead as shown in Figure 9-2. + +#### 9.2.4.1 OTUC availability (AVAIL) + +The AVAIL field is unused and should be set to a value of 1 for FlexO-1-RS 100G interfaces. For other cases it is reserved. + +The AVAIL field is located in frame 2, in overhead byte 3. + +#### 9.2.4.2 Payload type (PT) + +A one-byte FlexO payload type signal is defined to indicate the composition of the FlexO payload signal. The PT field is located in frame 5, in basic overhead byte 6 in all n FlexO instances. The code points are defined in Table 9-1. + +**Table 9-1 – FlexO payload type code points** + +| MSB
1 2 3 4 | LSB
5 6 7 8 | Hex code
(Note 1) | Interpretation | +|----------------|----------------|----------------------|------------------------------------------------------------------------| +| 0 0 0 0 | 0 0 0 0 | 00 | BMP mapping OTUCn into FlexO-n | +| 0 0 0 0 | 0 0 0 1 | 01 | Experimental mapping (Note 2) | +| 0 0 0 0 | 0 0 1 0 | 02 | GMP mapping OTUCn into FlexO-n | +| 0 0 0 0 | 0 1 0 0 | 04 | Reserved for FlexOsec SquelchText value | +| 0 0 0 0 | 0 1 0 1 | 05 | GMP mapping Ethernet into FlexO-ne | +| 0 1 0 0 | 0 0 0 0 | 40 | Reserved OIF 800ZR mapping and multiplexing of Ethernet clients | +| 0 1 0 0 | 0 0 0 1 | 41 | Reserved OIF 800ZR PRBS test pattern | +| 1 0 0 0 | x x x x | 80-8F | Reserved codes for proprietary use (Note 3) | +| 0 1 0 1 | 0 1 0 1 | 55 | Reserved for FlexO LCK maintenance signal, see clause 8.5 | +| 1 1 1 1 | 1 1 1 0 | FE | PRBS test pattern, see clause 10.5 | +| 1 1 1 1 | 1 1 1 1 | FF | Reserved for FlexO AIS maintenance signals, see clause 8.5 | + +NOTE 1 – There are 230 spare codes left for future international standardization. Refer to Annex A of [b-ITU-T G.806] for the procedure to obtain one of these codes for a new payload type. + +NOTE 2 – Value "01" is only to be used for experimental activities in cases where a mapping code is not defined in this table. Refer to Annex A of [b-ITU-T G.806] for more information on the use of this code. + +NOTE 3 – These 16 code values will not be subject to further standardization. Refer to Annex A of [b-ITU-T G.806] for more information on the use of these codes. + +#### 9.2.4.3 Client specific overhead allocation + +Fourteen bytes are reserved in the FlexO basic overhead for the client mapping specific overhead. These bytes are located in rows 2 to 8, basic overhead byte 5; rows 2 to 4 and 6 to 8, basic overhead byte 6; and row 8, basic overhead byte 3. + +The use of these bytes depends on the specific client signal mapping and is activated per PT configuration. + +### 9.2.5 Cyclic redundancy check (CRC) + +The CRC-16 (2 bytes) is located in overhead bytes 11 and 12 of each FlexO frame. The CRC protects the integrity of the OH fields in bytes 2 to 10 and excludes the MFAS, OSMC and FCC1 fields. The CRC-16 uses the $G(x) = x^{16} + x^6 + x^5 + x^3 + 1$ generator polynomial and is calculated as follows: + +- 1) The overhead bytes 2 to 10 of the OH frame are taken in network byte order, most significant bit first, to form a 72-bit pattern representing the coefficients of a polynomial $M(x)$ of degree 71. +- 2) $M(x)$ is multiplied by $x^{16}$ and divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ of degree 15 or less. +- 3) The coefficients of $R(x)$ are considered to be a 16-bit sequence, where $x^{15}$ is the most significant bit. +- 4) This 16-bit sequence is the CRC-16 where the first bit of the CRC-16 to be transmitted is the coefficient of $x^{15}$ and the last bit transmitted is the coefficient of $x^0$ . + +The demapper process performs steps 1-3 in the same manner as the mapper process, except that here, the $M(x)$ polynomial of step 1 includes the CRC-16 bits in received order and has degree 87. In the absence of bit errors, the remainder shall be 0. + +### 9.2.6 FlexO management communications channel (FCC1) + +An 896-bit (112 bytes) field per multi-frame is provided for a FlexO-x(e)- interface generic management communications channel. As shown in Figure 9-6, these fields are allocated across all 8 frames of the multi-frame of the first FlexO instance. This provides a clear channel. Format and content of the management channel is outside the scope of this recommendation. + +The FCC1 field is located in all frames, in overhead bytes 13 to 26. If unused, the management channel shall be filled with all-0s prior to scrambling. The FCC1 bytes provide a communication channel per FlexO-x(e)- interface with an approximate bandwidth of ~18 Mbit/s. + +![Diagram showing the transmission order of FCC1 bytes across multiple frames. It displays Frame 1, Frame 2, and Frame 3, with overhead bytes 13 through 26 highlighted for each frame. An arrow below indicates the transmission order from left to right. The diagram is labeled G.709.1(24) in the bottom right corner.](7ede87328f6b696dcffa65ebc4570cc8_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|----------|---------|----|----|----|----|----|----|----|----|----|----|----|----|----|---------|----|----|----|----|----|----|----|----|----|----|----|----|----|---------|----|----|-----| +| | Frame 1 | | | | | | | | | | | | | | Frame 2 | | | | | | | | | | | | | | Frame 3 | | | | +| OH bytes | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 13 | 14 | 15 | ... | +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +Transmission order → + +G.709.1(24) + +Diagram showing the transmission order of FCC1 bytes across multiple frames. It displays Frame 1, Frame 2, and Frame 3, with overhead bytes 13 through 26 highlighted for each frame. An arrow below indicates the transmission order from left to right. The diagram is labeled G.709.1(24) in the bottom right corner. + +**Figure 9-6 – FCC1 transmission order** + +NOTE – Editions prior to 2.5 of this Recommendation referred to this field as FCC. + +### 9.2.7 FlexO reserved overhead (RES) + +112.5 bytes of the FlexO basic overhead field in the FlexO multi-frame structure are reserved for future international standardization. These bytes/bits are located in frame 1/byte 5, frame 2/byte 4, frames 3 to 7/bytes 3 to 4, frame 8 byte 4 and frames 1 to 8/bytes 29 to 40. These bytes/bits are set to all-0s prior to scrambling. + +### 9.2.8 OTN synchronization message channel (OSMC) + +A 128-bit (16 bytes) field per multi-frame is provided for an OTN synchronization message channel (OSMC). As shown in Figure 9-2, these are allocated across all eight frames of the multi-frame. This field provides a clear channel, to transport synchronization status message (SSM) and precision time protocol (PTP) messages. + +The OSMC is only defined on the first FlexO instance (lowest IID value) of a FlexO-x(e)--m interface group. + +The OSMC field is located in all frames, in overhead bytes 27 and 28. If unused, the OTN synchronization message channel bytes shall be filled with all-0s prior to scrambling. The OSMC bytes are combined to provide a messaging channel, as illustrated in Figure 9-7, with an approximate bandwidth of 2.56 Mbit/s per 100G interface. + +![Diagram showing the transmission order of OSMC bytes across multiple frames. It shows three frames (1, 2, 3) with overhead bytes 27 and 28. Below the bytes are boxes representing the OSMC field. An arrow labeled 'Transmission order' points from left to right. The diagram is labeled G.709.1(24).](09955ff8214ffb6947951fc0f60eb6ab_img.jpg) + +| | | | | | | | | +|----------|----|----|----|----|----|----|-----| +| Frame | 1 | | 2 | | 3 | | ... | +| OH bytes | 27 | 28 | 27 | 28 | 27 | 28 | | +| | | | | | | | | + +Transmission order → +G.709.1(24) + +Diagram showing the transmission order of OSMC bytes across multiple frames. It shows three frames (1, 2, 3) with overhead bytes 27 and 28. Below the bytes are boxes representing the OSMC field. An arrow labeled 'Transmission order' points from left to right. The diagram is labeled G.709.1(24). + +Figure 9-7 – OSMC transmission order + +The SSM and PTP messages within a FlexO instance are encapsulated into generic framing procedure frame-mapped (GFP-F) frames as specified in [ITU-T G.7041]. PTP event messages are timestamped and after encapsulation into GFP-F frames, they are inserted into the OSMC as specified in this clause. GFP-F encapsulated SSM messages (and PTP non-event messages) are inserted into the OSMC at the earliest opportunity. Generic framing procedure (GFP) idle frames may be inserted between successive GFP frames. + +The mapping of GFP frames is performed by aligning the byte structure of every GFP frame with the byte of the OSMC overhead field. Since the GFP frames are of variable length and may be longer than 16 bytes, a GFP frame may cross the FlexO multi-frame boundary. + +#### 9.2.8.1 Generation of event message timestamp + +The message timestamp point [ITU-T G.8260] for a PTP event message transported over the OSMC shall be the 32-frame multi-frame event (corresponding to MFAS[4:8] = 00000) preceding the beginning of the GFP frame, in which the PTP event message is carried. Since the GFP frames may be longer than 64 bytes, a frame may cross the FlexO 32-frame multi-frame boundary. Figure 9-8 shows a timestamp diagram example and the relationship to the GFP frames (PTP message). + +All PTP event messages are timestamped on egress and ingress interfaces. The timestamp shall be the time at which the event message timestamp point passes the reference plane [ITU-T G.8260] marking the boundary between the PTP node (i.e., OTN node) and the network. + +Event message timestamps are generated at the FlexO Access Point. The message timestamp point is specified below as the 32-frame FlexO multi-frame event corresponding to MFAS[4:8] = 00000. For this application, the FlexO multi-frame event is defined as when the first bit of the first alignment mechanism (AM), corresponding to MFAS[4:8] = 00000 frame, on a lane crosses between the PTP node (i.e., OTN node) and the network (i.e., the analogous point to Ethernet MDI). In the case of a multi-lane PHY, the PTP path data delay is measured from the beginning of the AM field at the reference plane, which is equivalent to Ethernet MDI of the lane with the maximum media propagation delay. In practice: + +- On egress interfaces, since the AM fields for all lanes are transmitted at the same time conceptually, any AMs can be used for timestamping. +- On ingress interfaces, AM fields are present in all the lanes, but different lanes may be skewed from each other. The last received AM across all the lanes shall be used for timestamping. + +NOTE 1 – The first byte of a GFP (PTP event message) frame is inserted into the FlexO OSMC between 4 and 31 frames after the 32-frame multi-frame boundary. + +NOTE 2 – The guard band of four frames is defined to simplify implementation. + +![Timing diagram example for OSMC showing three consecutive 32-frame FlexO multi-frame periods. A horizontal axis at the bottom is labeled 'Time'. Above the axis, three double-headed arrows indicate the duration of each '32-frame FlexO multi-frame period'. Below each period, a yellow box labeled 'PTP event message via OSMC' is shown. Red curved arrows point from the start of each multi-frame period to its corresponding PTP event message box. A vertical double-headed arrow on the far left, labeled 'Y=4', indicates the time offset from the start of the first multi-frame period to the start of the first PTP event message. The text 'G.709.1(24)' is in the bottom right corner.](eb03559a4d92ea9ebd63ea9be663c50a_img.jpg) + +Timing diagram example for OSMC showing three consecutive 32-frame FlexO multi-frame periods. A horizontal axis at the bottom is labeled 'Time'. Above the axis, three double-headed arrows indicate the duration of each '32-frame FlexO multi-frame period'. Below each period, a yellow box labeled 'PTP event message via OSMC' is shown. Red curved arrows point from the start of each multi-frame period to its corresponding PTP event message box. A vertical double-headed arrow on the far left, labeled 'Y=4', indicates the time offset from the start of the first multi-frame period to the start of the first PTP event message. The text 'G.709.1(24)' is in the bottom right corner. + +**Figure 9-8 – Timing diagram example for OSMC** + +NOTE 3 – This time synchronization over FlexO-x-RS interface implementation does not generate event message timestamps using a point other than the message timestamp point [ITU-T G.8260]. + +In this time synchronization over FlexO-x-RS interface implementation, the timestamps are generated at a point removed from the reference plane. Furthermore, the time offset from the reference plane is likely to be different for inbound and outbound event messages. To meet the requirement of this clause, the generated timestamps should be corrected for these offsets. Figure 19 in [b-IEEE 1588] illustrates these offsets. Based on this model, the appropriate corrections are as follows: + +$$\langle \text{egressTimestamp} \rangle = \langle \text{egressMeasuredTimestamp} \rangle + \text{egressLatency}$$ + +$$\langle \text{ingressTimestamp} \rangle = \langle \text{ingressMeasuredTimestamp} \rangle - \text{ingressLatency}$$ + +where the actual timestamps $\langle \text{egressTimestamp} \rangle$ and $\langle \text{ingressTimestamp} \rangle$ measured at the reference plane are computed from the detected, i.e., measured, timestamps by their respective latencies. Failure to make these corrections results in a time offset between the follower and leader. + +The PTP timestamp is associated with the first FlexO instance (lowest IID value) of a FlexO-x(e)--m interface group. + +## 9.3 Extended overhead (EOH) description + +The FlexO EOH field is contained in the 480 bits (60 bytes) following the FlexO frame AM field. The EOH overhead does not use the 8-frame multi-frame. The EOH structure is shown in Figure 9-9. + +NOTE – FlexO extended overhead was specified as FlexO PAD in Editions 1.0 to 2.2 of this Recommendation. + +Extended overhead that is not used for a specific application contains the all-0's pattern. + +FlexO extended overhead applications include FlexOfec, FlexOsec and regen. Further applications may be defined in future editions of this Recommendation. + +![Figure 9-9: FlexO extended overhead diagrams for instance #1 and instance #2-x. The diagrams show the structure of the overhead bytes (1-60) and the specific fields for each instance. Instance #1 includes FlexOfec (FBA, RES), Regen (RMFAS, RES, RTTI, RSTAT, FCC0), FlexOsec (Authentication tag, KCC, RES, CST, RES, FN, RES), and a final RES byte. Instance #2-x is similar but the Regen application fields are RMFAS, RES, RSTAT, and RES. A legend defines the fields: RMFAS (Regen MFAS), RTTI (Regen trail trace identifier), RSTAT (Regen status), FCC0 (FlexO communication channel), AT (Authentication tag), CST (Cipher suite type), FN (Frame number), KCC (Key exchange communications channel), KI (Key index), FBA (FEC block alignment), and RES (Reserved for future international standardization).](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg) + +**EOH bytes for FlexO instance #1** + +1 ..... 4 5 ..... 20 21 ..... 52 53 ..... 60 + +FlexOfec Regen FlexOsec RES + +FlexOfec application + +1 2 ... 4 + +FBA RES + +Regen application + +5 6 ... 10 11 12 13 ..... 20 + +RMFAS RES RTTI RSTAT FCC0 + +FlexOsec application + +21 ..... 36 37 38 39 40 41 ..... 48 49 ..... 52 + +Authentication tag KCC RES CST RES FN RES + +**EOH bytes for FlexO instance #2-x** + +1 ..... 4 5 ..... 20 21 ..... 52 53 ..... 60 + +FlexOfec Regen FlexOsec RES + +FlexOfec application + +1 2 ... 4 + +FBA RES + +Regen application + +5 6 ... 11 12 13 ..... 20 + +RMFAS RES RSTAT RES + +FlexOsec application + +21 ..... 36 37 38 39 40 41 ..... 48 49 ..... 52 + +Authentication tag KCC RES CST RES FN RES + +RMFAS: Regen MFAS +RTTI: Regen trail trace identifier +RSTAT: Regen status +FCC0: FlexO communication channel +AT: Authentication tag +CST: Cipher suite type +FN: Frame number +KCC: Key exchange communications channel +KI: Key index +FBA: FEC block alignment +RES: Reserved for future international standardization + +G.709.1(24) + +Figure 9-9: FlexO extended overhead diagrams for instance #1 and instance #2-x. The diagrams show the structure of the overhead bytes (1-60) and the specific fields for each instance. Instance #1 includes FlexOfec (FBA, RES), Regen (RMFAS, RES, RTTI, RSTAT, FCC0), FlexOsec (Authentication tag, KCC, RES, CST, RES, FN, RES), and a final RES byte. Instance #2-x is similar but the Regen application fields are RMFAS, RES, RSTAT, and RES. A legend defines the fields: RMFAS (Regen MFAS), RTTI (Regen trail trace identifier), RSTAT (Regen status), FCC0 (FlexO communication channel), AT (Authentication tag), CST (Cipher suite type), FN (Frame number), KCC (Key exchange communications channel), KI (Key index), FBA (FEC block alignment), and RES (Reserved for future international standardization). + +**Figure 9-9 – FlexO extended overhead** + +### 9.3.1 FlexOfec overhead + +FlexOfec overhead application in this Edition is associated with the staircase FEC (SC FEC) specified in [ITU-T G.709.3]. + +#### 9.3.1.1 Staircase FEC block alignment (FBA) field + +Figure 9-9 shows the "FBA" overhead byte in byte 1 of the extended overhead field. Refer to [ITU-T G.709.3] for the FBA specification. + +### 9.3.2 FlexOsec overhead + +FlexOsec provides secure communications between two FlexO interfaces which are interconnected by an unsecured fibre, a point-to-point optical line system or an optical network. An authenticated and authorized FlexO security entity within each FlexO interface uses the unsecured transmission through the fibre, point-to-point optical line system or optical network to provide the secure transmission to its FlexO client. + +The FlexOsec overhead is specific and defined for all FlexO instances within a FlexO group interface. The FlexOsec overhead is illustrated in Figure 9-9 and contains the following fields: + +- Authentication tag (AT) +- Frame number (FN) +- Key index (KI) +- Cipher suite type (CST) +- Key exchange communication channel (KCC) +- Bits reserved for future international standardization (RES) + +#### 9.3.2.1 Authentication tag (AT) + +A 128-bit (16 byte) authentication tag field is provided to secure the integrity of transport of the bits in a FlexO frame. The cryptographic algorithms used to generate the integrity value and the various portions of the authenticated FlexO frame depend on the cipher suite type used. Additional details can be found in Annex A. + +The AT overhead field is used individually per FlexO instance within a group interface. An authentication tag calculated over (portions of) a FlexO instance #i frame #j is inserted in the following FlexO instance #i frame #j+1. + +The AT field is located in bytes 21 to 36 of the extended overhead field. + +#### 9.3.2.2 Frame number (FN) + +A 64-bit (8 byte) frame number field is provided to synchronize the invocation counters on both ends of a FlexOsec connection. The use of FN as invocation counter and initialization vector (IV) construction is specific to the cipher suite type and further defined in Annex A. An IV is a nonce that is associated with an invocation of authenticated encryption on a particular plaintext and additional authenticated data (AAD). + +The FlexOsec frame number is also used to create a 4-frame FlexOsec multi-frame which is separate to the FlexO MFAS multi-frame. FN is applicable to the current FlexO frame. FN increments by 1 on every FlexO frame, however on key change events FN is assumed to be reset to 0. + +The FN field is located in bytes 41 to 48 of the extended overhead field. + +#### 9.3.2.3 Key index (KI) + +A 2-bit key index field is provided for an in-band mechanism to coordinate use of keys on both ends. At the source, the KI value increments on key change/roll events. The value of KI is constant across 4-frame FlexOsec multi-frames and increments on multi-frame boundaries as defined by $FN[63, 64] = 00$ . The value of KI in the current multi-frame #k indicates the key to be used starting at the next multi-frame #k+1. Figure 9-10 shows key index boundaries. + +![Diagram illustrating key index boundaries in a multi-frame sequence. It shows columns 1 to 5140 and rows 1 to 128. The diagram highlights four multi-frame boundaries where the Key Index (KI) is consistent across frames. The Frame Number (FN) for the 64th and 65th rows is shown for each boundary: FN[63, 64] = 00, FN[63, 64] = 01, FN[63, 64] = 10, and FN[63, 64] = 11. The first frame of each multi-frame contains AM, EOH, and BOH fields. A note indicates that the KI is consistent across the 4-frame multi-frame and is accepted/used for the next multi-frame boundary. The diagram is labeled G.709.1(24).](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg) + +Diagram illustrating key index boundaries in a multi-frame sequence. It shows columns 1 to 5140 and rows 1 to 128. The diagram highlights four multi-frame boundaries where the Key Index (KI) is consistent across frames. The Frame Number (FN) for the 64th and 65th rows is shown for each boundary: FN[63, 64] = 00, FN[63, 64] = 01, FN[63, 64] = 10, and FN[63, 64] = 11. The first frame of each multi-frame contains AM, EOH, and BOH fields. A note indicates that the KI is consistent across the 4-frame multi-frame and is accepted/used for the next multi-frame boundary. The diagram is labeled G.709.1(24). + +**Figure 9-10 – Key index boundaries** + +The key index is used to select among 4 possible keys as shown in Table 9-2. + +**Table 9-2 – Key index coding** + +| KI bits [12] | Interpretation | +|--------------|----------------| +| 00 | Key #0 | +| 01 | Key #1 | +| 10 | Key #2 | +| 11 | Key #3 | + +The KI field is located in bits 1 and 2 of byte 39 of the extended overhead field. + +#### 9.3.2.4 Cipher suite type (CST) + +A 6-bit cipher suite type field is provided to identify and distinguish different types of ciphers (including absence of cipher), profiles or applications. The code points are defined in Table 9-3. Code point value 000000 indicates that there is no source FlexOsec. + +The CST field is located in bits 3 to 8 of byte 39 of the extended overhead field. + +**Table 9-3 – Cipher suite type code points** + +| CST bits
[123456] | Interpretation | +|----------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 0 0 0 0 0 | No source FlexOsec | +| 0 0 0 0 0 1 | GCM-AES-256 FlexOsec without OH encryption. Refer to Annex A.1. | +| 0 0 0 0 1 0 – 1 1 0 1 1 1 | Codepoints reserved for future standardized cryptographic cipher suites (defined by national or international standards bodies or government agencies) for use with FlexO. | +| 0 1 0 1 0 1 | Reserved for FlexO LCK maintenance signal, see clause 8.5 | +| 1 1 1 0 0 0 – 1 1 1 1 1 0 | Reserved codes for proprietary use (Note) | +| 1 1 1 1 1 1 | Reserved for FlexO AIS maintenance signal, see clause 8.5 | +| NOTE – These 7 code values will not be subject to further standardization. | | + +#### 9.3.2.5 Key exchange communication channel (KCC) + +An optional 8-bit (1 byte) key exchange communication channel field is provided to exchange key agreement protocols in-band using FlexO overhead. + +The KCC field is located in byte 37 of the extended overhead field. + +NOTE 1 – Key agreement protocols may be vendor, operator or user specific for the case that multi-vendor, multi-operator or multi-user interoperability is not required. + +NOTE 2 – KCC is only present in the first FlexO-x(e)- interface. + +#### 9.3.2.6 Reserved (RES) + +6 bytes of the FlexOsec overhead area are reserved for future international standardization. These are located in bytes 38, 40, 49, 50, 51 and 52. These bytes/bits are set to all-0s. + +### 9.3.3 FlexO regeneration overhead (regen) + +Regen overhead is used to enable FlexO regeneration functions and is terminated on every interface. NOTE – Implementations developed prior to Edition 2.5 of this Recommendation do not support the regen overhead and associated functions. + +The regen overhead is illustrated in Figure 9-9 and contains the following fields: + +- Regen multi-frame alignment signal (RMFAS) +- Regen status (RSTAT) +- Regen trail trace identifier (RTTI) +- FlexO regen communication channel (FCC0) + +#### 9.3.3.1 Regen multi-frame alignment signal (RMFAS) + +An 8-bit (1 byte) regen multi-frame alignment signal field is provided and incremented in every FlexO frame. This RMFAS field counts 0x00 to 0xFF and provides a 256-frame FlexO multi-frame. This multi-frame is used to lock 2-frame, 4-frame, 8-frame, 16-frame, 32-frame, etc. multi-frame structures of overhead to the FlexO frame. The RMFAS sequence is identical to what is shown in Figure 9-3 for the MFAS. The RMFAS (EOH) and MFAS (BOH) increment independently. + +#### 9.3.3.2 Regen status (RSTAT) + +An 8-bit (1 byte) field, as shown in Figure 9-11, is provided for general purpose status indication. + +- Remote fault indication (RF) +- Local and remote degradates (LD, RD) +- Reserve (RES) + +![Diagram of the FlexO EOH RSTAT field showing 8 bits. Bit 1 is RF, bits 2-6 are RES, bit 7 is RD, and bit 8 is LD.](759c7d62402f0b4651ddce292be5bdef_img.jpg) + +| | | | | | | | | | +|------|----|-----|---|---|---|----|----|---| +| Bits | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| | RF | RES | | | | RD | LD | | + +G.709.1(24) + +Diagram of the FlexO EOH RSTAT field showing 8 bits. Bit 1 is RF, bits 2-6 are RES, bit 7 is RD, and bit 8 is LD. + +Figure 9-11 – FlexO EOH RSTAT field + +The RSTAT field is located in all frames, in EOH byte 12 as shown in Figure 9-9. + +##### 9.3.3.2.1 Remote fault indication (RF) + +For regen section monitoring, a single bit remote fault indication (RF) conveys the signal fail status detected at the remote FlexO sink function in the upstream direction. + +RF is set to "1" to indicate a remote defect indication; otherwise, it is set to "0". + +##### 9.3.3.2.2 Degrade indication (LD/RD) + +The 2-bit link degrade indication field is defined to indicate the quality of the FlexO-x(e)- interface. Local and remote degrade (LD and RD) fields are asserted and set to "1" on detection of terminated FlexO-x(e)- pre-FEC BER link degrade; otherwise they are set to "0". LD is propagated in the forward direction and can cover multiple regen spans. RD is propagated in the backwards direction and only covers a single FlexO-x(e)- interface span. + +NOTE – Annex C.2 illustrates the propagation of LD/RD in RSTAT for the case of multiple optical links and the interworking with the native indications in an Ethernet client link. + +##### 9.3.3.2.3 Reserved (RES) + +Five bits of the RSTAT byte are reserved for future international standardization as shown in Figure 9-11. These bits are set to "0". + +#### 9.3.3.3 Regen trail trace identifier (RTTI) + +For FlexO section monitoring, a one byte regen trail trace identifier (RTTI) overhead is defined to transport the 64-byte RTTI signal specified in clause 15.2 and Figure 15-4 of [ITU-T G.709]. + +The FlexO-x(e)- interface contains one RTTI overhead in the first instance as shown in Figure 9-9. + +The 64-byte RTTI signal shall be aligned with the FlexO regen multi-frame (RMFAS). Byte 0 of the 64-byte RTTI signal shall be present when the value of the FlexO RMFAS is xx00 0000. + +#### 9.3.3.4 FlexO regen communication channel (FCC0) + +A 64-bit (8 bytes) field per frame is provided for a FlexO-x(e)- interface regen generic management communications channel. As shown in Figure 9-9, this field is located in the EOH in byte locations 13 to 20 of the first FlexO instance. + +The FCC0 bytes provide a communication channel per FlexO-x(e)- interface with an approximate bandwidth of ~10 Mbit/s. + +# 10 FlexO mapping procedures + +FlexO payload can be mapped with different clients, such as OTUCn, Ethernet and pseudo random binary sequence (PRBS). + +## 10.1 BMP mapping of OTUCn client into FlexO-n + +The n OTUC instances of a single OTUCn are mapped to a single FlexO-n (group of n FlexO instances). For the reordering of FlexO members and deskewing of the OTUCn client after demapping from FlexO-n, see clause 10.4.1. + +An OTUCn is mapped in order into n FlexO instances with ascending IID values. + +### 10.1.1 Distributing OTUCn and combining OTUC instances + +An OTUCn frame structure is specified in clause 11.3 [ITU-T G.709] and contains n instances of OTUC frame structures. As shown in Figure 10-1, the FlexO source adaptation consists of splitting the OTUCn frame into $n \times$ OTUC instances. Similarly, the sink adaptation combines $n \times$ OTUC instances into an OTUCn. A single OTUC instance is then associated to a FlexO instance, and multiple FlexO instances are associated to a FlexO-n. + +![Diagram illustrating the distribution of an OTUCn frame into multiple FlexO frames. The OTUCn frame is split into n OTUC instances, which are then mapped to n FlexO frames, which are finally combined into a single FlexO-n payload.](84e5b251aa38db522f76f5cc3afcb853_img.jpg) + +The diagram shows the hierarchical decomposition of an OTUCn frame. At the top, a box labeled 'OTUCn SMOH' and 'OTUCn' is shown. Two arrows point down from this box to two separate boxes, each labeled 'OTUC'. Between these two boxes is a vertical ellipsis. From each 'OTUC' box, an arrow points down to a dashed box labeled 'BMP #1' and 'BMP #n'. Between these dashed boxes is another vertical ellipsis. From each 'BMP' box, an arrow points down to a box labeled 'FlexO frame #1' and 'FlexO frame #n'. Between these boxes is a third vertical ellipsis. Finally, arrows from the 'FlexO frame' boxes point down to a single, wide box at the bottom labeled 'FlexO-n (Payload)'. In the bottom right corner of the diagram area, the text 'G.709.1(24)' is present. + +Diagram illustrating the distribution of an OTUCn frame into multiple FlexO frames. The OTUCn frame is split into n OTUC instances, which are then mapped to n FlexO frames, which are finally combined into a single FlexO-n payload. + +Figure 10-1 – OTUCn distributed into FlexO-n + +### 10.1.2 FlexO multi-frame payload + +For bit-synchronous mapping procedure (BMP), fixed stuffing is used to pad the OTUCn up to a FlexO-n rate. In order to pad the payload area, an 8-frame FlexO multi-frame structure is defined. It uses the three least significant bits of the multi-frame alignment signal (MFAS) overhead to identify the eight frames within the multi-frame. + +The FlexO multi-frame structure is shown in Figure 10-2. The multi-frame contains seven fixed stuff (FS) locations in the payload area of FlexO frames, each containing 1,280 bits. These fixed-stuff locations are located in row 65, columns 1 to 1,280 of the first seven frames within the multi-frame. The last frame within the multi-frame does not contain fixed stuff. + +The fixed stuff bits are filled with all-0s and are not checked at the receiver sink function. + +The FlexO multi-frame payload, excluding the FS locations, consists of 5,244,160 bits (655,520 bytes) out of the total 5,263,360 bits (657,920 bytes) per FlexO multi-frame. + +![Diagram of FlexO BMP multi-frame structure showing columns (1 to 5140) and rows (1 to 128) for multiple frames. Each frame starts with AM, EOH, and BOH headers. Row 65 contains Fixed Stuff (FS) for the first seven frames. The eighth frame does not contain FS. MFAS bits [678] are shown for each frame: 000 for Frame 1, 001 for Frame 2, 110 for Frame 7, and 111 for Frame 8.](dd5771673aececa53d42ece89218299d_img.jpg) + +The diagram illustrates the FlexO BMP multi-frame structure. It shows a grid of columns (1 to 5140) and rows (1 to 128) for multiple frames. Each frame starts with AM, EOH, and BOH headers. Row 65 contains Fixed Stuff (FS) for the first seven frames. The eighth frame does not contain FS. MFAS bits [678] are shown for each frame: 000 for Frame 1, 001 for Frame 2, 110 for Frame 7, and 111 for Frame 8. + +Columns: 1, ..., 5140 + +Rows: 1, 2, ..., 64, 65, ..., 128 + +Frame 1: MFAS bits [678] = 000 + +Frame 2: MFAS bits [678] = 001 + +Frame 7: MFAS bits [678] = 110 + +Frame 8: MFAS bits [678] = 111 + +G.709.1-Y.1331.1(18)-Amd.2(20)\_F10-2 + +Diagram of FlexO BMP multi-frame structure showing columns (1 to 5140) and rows (1 to 128) for multiple frames. Each frame starts with AM, EOH, and BOH headers. Row 65 contains Fixed Stuff (FS) for the first seven frames. The eighth frame does not contain FS. MFAS bits [678] are shown for each frame: 000 for Frame 1, 001 for Frame 2, 110 for Frame 7, and 111 for Frame 8. + +**Figure 10-2 – FlexO BMP multi-frame structure** + +The FlexO multi-frame payload area is divided in 128-bit blocks. The 128-bit blocks are aligned to the start of a FlexO payload area (following AM, EOH and BOH). The FlexO frame payload consists of 5,120 blocks (frame #1-7 of the multi-frame, with fixed stuff payload) and 5,130 blocks (frame eight of the multi-frame, without fixed stuffing). + +NOTE – This 128-bit (16-byte) word/block alignment of the 100G OTUC is analogous to the 66b block alignment of a 100G Ethernet PCS stream that is kept through the clause 91 [IEEE 802.3] adaptation process. + +### 10.1.3 Mapping of OTUC into FlexO multi-frame payload + +Groups of 128 successive bits (16 bytes) of the OTUC signal are mapped into a 128-bit block of the FlexO frame payload area using a bit-synchronous mapping procedure (BMP) control mechanism as specified in clause 17 of [ITU-T G.709]. The 128-bit group of OTUC is aligned to the OTUC frame structure. + +The OTUC frame structure is floating in respect to the FlexO frame. + +The serial bit stream of an OTUC signal is inserted into the FlexO frame payload so that the bits will be transmitted on the FlexO-x- interface in the same order that they were received at the input of the mapper function. + +In clause 8.3, the shown bit rate ratio between FlexO frame and the OTUC client is 4112/4097. The bit rate of the OTUC signal (with up to $\pm 20$ ppm bit-rate tolerance) is $1/n$ the bit rate of the OTUCn client specified in [ITU-T G.709] Table 7-1. + +#### 10.1.3.1 Mapping of OTUC into FlexO frame + +There exists a one-to-one relationship between an OTUC and a FlexO instance. The FlexO payload area is segmented in 128-bit blocks. The OTUC is mapped in contiguous 128-bit segments. + +There are $(5,140 \times 128 \times 8 - 1,280 \times 15) / (239 \times 16 \times 8 \times 4) \sim 42.86$ OTUC frames per FlexO multi-frame. The numerator is the number of payload bits in the FlexO multi-frame, which is computed based on the number of bits in the multi-frame (5140 bits per row times 128 rows per frame times 8 frames per multi-frame) minus the bits used for overhead or fixed stuff – 8 instances of 1280 bits of overhead in the multi-frame, plus 7 instances of 1280 bits of fixed stuff. The denominator is the number of bits per OTUC frame, which would be more clearly expressed as $3824 \text{ bytes/row} \times 8 \text{ bits/byte} \times 4 \text{ rows/frame}$ . This results in $\sim 5$ OTUC frames per FlexO frame, or a new OTUC frame every $\sim 24$ FlexO frame rows, as shown in Figure 10-3. + +![Diagram illustrating the mapping of OTUC blocks into 128-bit FlexO payload blocks. The OTUC frame structure shows OH (Overhead) and Payload. The FlexO frame structure shows Columns 1 to 5140, with AM (Alignment) and OH (Overhead) blocks. Arrows indicate the mapping of OTUC blocks into the FlexO payload area. A note states: '128-bit block spills over FlexO frame payload and is not a perfect multiple'. The diagram is labeled G.709.1(24).](dc1f232cfd39be5c20b21374ad4c04c0_img.jpg) + +The diagram illustrates the mapping of OTUC blocks into 128-bit FlexO payload blocks. At the top, an OTUC frame is shown with an Overhead (OH) section and a Payload section. Below it, the FlexO frame structure is depicted as a grid of columns, numbered 1 to 5140. The first column is labeled 'Columns' and contains 'AM' (Alignment) and 'OH' (Overhead) blocks. Arrows show the mapping of OTUC blocks into the FlexO payload area. A note at the bottom indicates that the 128-bit block spills over the FlexO frame payload and is not a perfect multiple. The diagram is labeled G.709.1(24). + +Diagram illustrating the mapping of OTUC blocks into 128-bit FlexO payload blocks. The OTUC frame structure shows OH (Overhead) and Payload. The FlexO frame structure shows Columns 1 to 5140, with AM (Alignment) and OH (Overhead) blocks. Arrows indicate the mapping of OTUC blocks into the FlexO payload area. A note states: '128-bit block spills over FlexO frame payload and is not a perfect multiple'. The diagram is labeled G.709.1(24). + +**Figure 10-3 – OTUC mapped into 100G FlexO frame payload** + +The FlexO frame payload does not divide elegantly into 128-bit blocks in a single row. The block will spill over and cross row boundaries as shown in Figure 10-3. The 128-bit alignment is always consistent across FlexO frames and the first 128-bit block starts immediately following the overhead area. + +During a signal fail condition of the incoming OTUCn signal, this failed incoming signal will contain the OTUCn-AIS signal as specified in clause 16.4.2 of [ITU-T G.709]. This OTUCn-AIS is then mapped into the n FlexO instances payload. + +### 10.1.4 Client mapping specific overhead + +The client mapping specific overhead shown in Figure 9-2 is not used for OTUCn BMP mapping and reserved. + +## 10.2 GMP mapping of Ethernet clients into FlexO-ne + +One or more Ethernet clients (with up to $\pm 100$ ppm bit-rate tolerance) can be mapped directly to $n$ FlexO instances (FlexO-ne) using generic mapping procedure (GMP). The $n$ FlexO frames are phase-locked and multi-frame aligned. Table 10-2 specifies the Ethernet clients defined by this mapping procedure. + +For each Ethernet client and prior to mapping, the mapper shall first recover the 257b client stream, which is referred to as the OTN reference signal. + +For 100GBASE-R clients, the bit interleaved parity (BIP) counters in the alignment markers are discarded. Because 100GBASE-R does scrambling prior to 257b transcoding, there is no descrambling performed for these clients. + +For 200GBASE-R and 400GBASE-R clients, the $am\_sf\langle 2:0 \rangle$ bits are extracted from the alignment markers prior to their removal and the 257b blocks are descrambled per clause 119.2.4.3 of [IEEE 802.3]. + +For 800GBASE-R client, the $am\_sf\langle 2:0 \rangle$ bits are extracted from the alignment markers prior to their removal, ORed together between both 400G flows and the two 257b streams are descrambled (400G flow 0 and 400G flow 1) without alignment markers as per clause 172.2.4.2 of [IEEE 802.3df]. + +At the demapper, the inverse processes are performed. For 200GE/400GE/800GE client types, the 257b blocks are scrambled following the procedures in clause 119.2.4.3 of [IEEE 802.3] and the $am\_sf\langle 2:0 \rangle$ fields extracted from the received FlexO frame overhead fields are processed as described in CSTAT clause 10.2.3.3 and inserted in the appropriate locations in the alignment marker fields. For 100GE clients the BIP counters are recomputed and inserted. For 100GE clients, no scrambling is performed (the blocks are intrinsically scrambled). + +![Diagram illustrating the mapping of multiple Ethernet clients (y_00GE 1, y_00GE 2, ..., y_00GE N) into a single FlexO-ne frame. Each client stream is processed through GMP processes (GMP #1 to GMP #y_1 for client 1, GMP #y_1+1 to GMP #y_1+y_2 for client 2, etc.) which are locked together in the mapper. The output of each GMP process is a FlexO frame (FlexO frame #1 to FlexO frame #y_1 for client 1, FlexO frame #y_1+1 to FlexO frame #y_1+y_2 for client 2, etc.). All these FlexO frames are then mapped into the payload area of a single FlexO-ne frame. A note 'G.709.1(24)' is present in the bottom right corner of the diagram.](1c9a5a80a4ed18fdfda1c8ae915966bf_img.jpg) + +Diagram illustrating the mapping of multiple Ethernet clients (y\_00GE 1, y\_00GE 2, ..., y\_00GE N) into a single FlexO-ne frame. Each client stream is processed through GMP processes (GMP #1 to GMP #y\_1 for client 1, GMP #y\_1+1 to GMP #y\_1+y\_2 for client 2, etc.) which are locked together in the mapper. The output of each GMP process is a FlexO frame (FlexO frame #1 to FlexO frame #y\_1 for client 1, FlexO frame #y\_1+1 to FlexO frame #y\_1+y\_2 for client 2, etc.). All these FlexO frames are then mapped into the payload area of a single FlexO-ne frame. A note 'G.709.1(24)' is present in the bottom right corner of the diagram. + +**Figure 10-4 – Mapping of Ethernet clients using GMP** + +For 100GBASE-R (100GE) clients, the 257b stream is mapped directly into the payload area of the corresponding FlexO instance. + +For $y_{00GBASE-R}$ ( $y=2,4,8$ ) clients, the 257b stream is split on a 257b block basis, in a round-robin fashion into $y$ 100G 257b streams which are mapped into the payload areas of the corresponding $y$ FlexO instances. + +### 10.2.1 FlexO frame and 4-frame multi-frame payload structure + +The FlexO frame payload area is divided in 257-bit payload blocks (see Figure 10-5). A 5b padding (following AM, EOH and BOH) is used to align to 257-bit multiples. The 257-bit payload blocks are aligned to the start of a FlexO payload following the 5b padding area. The FlexO frame payload contains 2555 257-bit blocks. + +NOTE – There is no fixed stuff in frames 1 to 7 of the FlexO 8-frame multi-frame in this mapping. + +![Diagram of a FlexO frame structure showing columns and rows. Columns are numbered 1 to 5140, with specific markers at 1280 and 1285. Rows are numbered 1 to 128. Row 1 contains a 5b padding area starting at column 1285. Row 2 contains payload blocks 16, 17, and 18. Row 128 contains 2555 payload blocks.](c76da2d73c064464051d1583fd80bb6b_img.jpg) + +The diagram illustrates the structure of a FlexO frame. The horizontal axis represents columns, numbered from 1 to 5140. The vertical axis represents rows, numbered from 1 to 128. Row 1 is a header row, with a '5b padding area' indicated between columns 1280 and 1285. Row 2 contains payload blocks, with blocks 16, 17, and 18 shown at the beginning. Row 128 contains 2555 payload blocks. Ellipses indicate that the structure continues between the shown elements. + +Diagram of a FlexO frame structure showing columns and rows. Columns are numbered 1 to 5140, with specific markers at 1280 and 1285. Rows are numbered 1 to 128. Row 1 contains a 5b padding area starting at column 1285. Row 2 contains payload blocks 16, 17, and 18. Row 128 contains 2555 payload blocks. + +**Figure 10-5 – FlexO frame showing payload with 257b blocks** + +The FlexO payload 4-frame multi-frame structure with 257-bit payload blocks in the payload area for the mapping of Ethernet client signals is illustrated in Figure 10-6. This per server payload area consists of 10220 257-bit blocks for Ethernet client mapping. Note that a y00GE client is GMP mapped over y phase-locked and 4-frame multi-frame aligned FlexO instances, so its server payload area actually consists of $10220 \times [y \times 257]$ -bit blocks. + +![Diagram of FlexO instance payload 4-frame multi-frame structure with 257-bit payload blocks for the GMP mapping of Ethernet client signal. The diagram shows a grid of columns (1 to 5140) and rows (MFAS bits 00, 01, 10, 11). Each frame contains 128 rows. Row 1 of each frame has 5b padding at columns 1280-1284, followed by payload blocks starting at column 1285. The payload blocks are 257 bits wide, starting at columns 1285, 2571, 5126, and 7681. The diagram shows the first few rows of each frame, with the last row of each frame containing 2555, 2570, 5110, 5125, 5145, 7665, 7680, 7700, and 10220 bits respectively. The diagram is labeled G.709.1(24).](7ae836e598020d937ed1478c2ef13025_img.jpg) + +Diagram of FlexO instance payload 4-frame multi-frame structure with 257-bit payload blocks for the GMP mapping of Ethernet client signal. The diagram shows a grid of columns (1 to 5140) and rows (MFAS bits 00, 01, 10, 11). Each frame contains 128 rows. Row 1 of each frame has 5b padding at columns 1280-1284, followed by payload blocks starting at column 1285. The payload blocks are 257 bits wide, starting at columns 1285, 2571, 5126, and 7681. The diagram shows the first few rows of each frame, with the last row of each frame containing 2555, 2570, 5110, 5125, 5145, 7665, 7680, 7700, and 10220 bits respectively. The diagram is labeled G.709.1(24). + +**Figure 10-6 – FlexO instance payload 4-frame multi-frame structure with 257-bit payload blocks for the GMP mapping of Ethernet client signal** + +The FlexO-ne payload bit rate is defined in Table 10-1. + +**Table 10-1 – FlexO-ne payload bit rates** + +| Interface Type | FlexO-ne payload nominal bit rate | FlexO-n(e) payload bit-rate tolerance | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------|---------------------------------------| +| FlexO-ne | $n \times 1594685/1900544 \times 766 \times 156\,250$ kbit/s | $\pm 20$ ppm | +| NOTE – The nominal FlexO-ne payload bit rate is approximately: $n \times 100\,425\,910.128$ kbit/s. The FlexO-ne payload bit rate can be derived from 156M Ethernet clock multiple as follows: $n \times 511/512 \times 514/544 \times 1445/1624 \times 766 \times 156\,250$ kbit/s. | | | + +### 10.2.2 Ethernet client + +Each adapted and mapped Ethernet client is a sequence of 257B blocks, with alignment markers removed. + +In the mapping (source) direction, the Ethernet clients are recovered using a similar process as described in [IEEE 802.3] clause 91 for 100GBASE-R, clause 119 for 200GBASE-R/400GBASE-R and clause 172 for 800GBASE-R. The lane(s) of the physical interface are bit-deinterleaved into logical lanes of 26 562 500 kbit/s. Lane alignment marker lock is acquired on each PCS lane, allowing lane deskew and reorder, and for FEC code word synchronization and error correction. The mapper shall extract the FEC parity bits and alignment markers, and performs descrambling (except for 100GBASE-R clients). The 257B/256B encoded signal is adapted into the FlexO-ne payload. Uncorrectable FEC code words shall be replaced with error control blocks in transcoded 257B block format. The order and bit ordering of these blocks shall match the ordering in the signal prior to FEC decoding. For 100GBASE-R clients, the alignment markers contain BIP counters which are discarded along with the alignment markers. The client am\_sf<2:0> bits are extracted for 200GBASE-R/400GBASE-R/800GBASE-R client types prior to alignment marker removal for transmission in the overhead fields of the FlexO frame and the 257B blocks are descrambled following the procedures in clause 119.2.4.3 of [IEEE 802.3] standard. + +The inverse process is implemented in the demapping (sink) direction. For 200GBASE-R/400GBASE-R client types, the 257b blocks are scrambled following the procedures in clause 119.2.4.3 of [IEEE 802.3] and the am\_sf<2:0> fields extracted from the received FlexO frame overhead fields are processed as described in CSTAT clause 10.2.3.3 and inserted in the appropriate locations in the alignment markers. For 100GBASE-R clients the BIP counters are recomputed and inserted. For 100GBASE-R clients, no scrambling is performed (the blocks are intrinsically scrambled). For 800GBASE-R, the 257B client data blocks are then deinterleaved into 400G flow 0 and 400G flow 1, to retrieve the 800GBASE-R client stream at the OTN reference signal as specified in clause 172.2.4.2 of [IEEE 802.3df]. Scrambling is performed and alignment markers and FEC parity bits are inserted on each 400G flow prior to the 800GBASE-R PCS lane distribution and interleaving into physical lanes at the PMA interface. + +The bit rates of the FlexO-ne Ethernet clients are listed in Table 10-2 and the corresponding replacement signals are listed in Table 10-3. + +**Table 10-2 – FlexO-ne Ethernet clients** + +| Client signal | Nominal bit rate (kbit/s) | Bit-rate tolerance (ppm) | +|-------------------|---------------------------------------------|--------------------------| +| 100GBASE-R | $16383/16384 \times 100\ 390\ 625$ | $\pm 100$ | +| 200GBASE-R | $20479/20480 \times 200\ 781\ 250$ | $\pm 100$ | +| 400GBASE-R | $20479/20480 \times 401\ 562\ 500$ | $\pm 100$ | +| 800GBASE-R (Note) | $2 \times 20479/20480 \times 401\ 562\ 500$ | $\pm 50$ | + +NOTE – This signal represents two aligned and unscrambled 256B/257B encoded 400G flows (400G flow 0 and 400G flow 1), without alignment markers. + +**Table 10-3 – Replacement signal for FlexO-ne Ethernet clients** + +| Client signal | Replacement signal | Bit-rate tolerance (ppm) | +|---------------|-----------------------|--------------------------| +| 100GBASE-R | Scrambled LF (Note 1) | ±100 | +| 200GBASE-R | LF (Note 1) | ±100 | +| 400GBASE-R | LF (Note 1) | ±100 | +| 800GBASE-R | LF (Note 2) | ±50 | + +NOTE 1 – The replacement signal for a 100GBASE-R, 200GBASE-R and 400GBASE-R signal is a continuous stream of LF sequence ordered sets encoded according to Figure 82-5 of [IEEE 802.3] using control block type 0x4B. 257B transcoding plus alignment marker insertion will be performed on the stream in the demapping direction. 200GBASE-R/400GBASE-R signals are then scrambled. + +NOTE 2 – The replacement signal for an 800GBASE-R signal is a continuous stream of LF sequence ordered sets encoded according to Figure 82-5 of [IEEE 802.3] using control block type 0x4B and then 256B/257B transcode as specified in clause 119.2.4.2 of [IEEE 802.3]. 257-bit blocks deinterleaving into two aligned 400G flows and alignment marker insertion will be performed on these two aligned 400G streams of 257-bit blocks in the demapping direction after which these signals are scrambled. + +### 10.2.3 Client mapping specific overhead + +The client mapping specific overhead shown in Figure 9-2 consists of a multiplex structure identifier (MSI), justification control (JC1-JC6) and client status (CSTAT) overhead as shown in Figure 10-7. The FlexO overhead locations are present in each FlexO instance. + +![Figure 10-7: Client mapping specific overhead for mapping Ethernet to FlexO-ne. The diagram shows the overhead structure across multiple frames (000 to 111) and columns (3 to 8). It details the placement of Justification Control (JC1-JC6), Multiplex Structure Identifier (MSI), and Client Status (CSTAT) overhead bytes. The MSI byte in frame 5, column 5 is expanded to show its bit structure: Occ (bit 1) and TPID (bits 2-8). A legend defines the TPID values for tributary ports 1 through 128. Other overhead details include 14-bit Cm sequences for JC1 and JC2, decrement/increment indicators for JC3, and client-specific 5-bit ΣCnD sequences for JC4, JC5, and JC6.](ac31fdfebb9751f7f10416dfe33bc872_img.jpg) + +**MFAS bits [678] Frame** + +| | | | | | +|-----|---|-------|--------|-----| +| 000 | 1 | 3 | 5 | 6 | +| 001 | 2 | | JC4 | JC1 | +| 010 | 3 | | JC5 | JC2 | +| 011 | 4 | | JC6 | JC3 | +| 100 | 5 | | MSI[x] | | +| 101 | 6 | | JC4 | JC1 | +| 110 | 7 | | JC5 | JC2 | +| 111 | 8 | CSTAT | JC6 | JC3 | + +**Client specific OH bytes for FlexO payload instance #1 to #n** + +**Bit** + +| | | | | | | | | | +|-----|-------|-----|-----|-----|-----|-----|-----------------------|------------------------------------------| +| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| JC1 | C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 ← 14-bit C m (m = y * 257) | +| JC2 | C9 | C10 | C11 | C12 | C13 | C14 | II | DI | +| JC3 | CRC-8 | | | | | | ↑ Decrement indicator | ↑ Increment indicator | + +| | | | | | | | | | +|-----|---|-----|---|---|---|-------|----|---------------------------------------------| +| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| JC4 | | RES | | | | D1 | D2 | D3 ← Client specific 5-bit ΣC nD | +| JC5 | | RES | | | | D4 | D5 | RES | +| JC6 | | RES | | | | CRC-3 | | | + +| | | | | | | | | | +|--------|------|------|---|---|---|---|---|---| +| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| MSI[x] | Occ. | TPID | | | | | | | + +0: Unallocated      000 000: Tributary port #1 +1: Allocated          000 001: Tributary port #2 +                          000 010: Tributary port #3 +                          ... +                          111 111: Tributary port #128 + +NOTE – x = 1 .. n + +G.709.1(24) + +Figure 10-7: Client mapping specific overhead for mapping Ethernet to FlexO-ne. The diagram shows the overhead structure across multiple frames (000 to 111) and columns (3 to 8). It details the placement of Justification Control (JC1-JC6), Multiplex Structure Identifier (MSI), and Client Status (CSTAT) overhead bytes. The MSI byte in frame 5, column 5 is expanded to show its bit structure: Occ (bit 1) and TPID (bits 2-8). A legend defines the TPID values for tributary ports 1 through 128. Other overhead details include 14-bit Cm sequences for JC1 and JC2, decrement/increment indicators for JC3, and client-specific 5-bit ΣCnD sequences for JC4, JC5, and JC6. + +**Figure 10-7 – Client mapping specific overhead for mapping Ethernet to FlexO-ne** + +#### 10.2.3.1 FlexO multiplex structure identifier (MSI) + +The FlexO multiplex structure identifier (MSI) overhead is located in frame 5, in overhead byte 5 in all n FlexO frames, as illustrated in Figure 10-8. The MSI indicates the Ethernet content of each FlexO instance payload. One byte is used for each FlexO instance. + +- The FlexO occupation (OCC) bit 1 indicates if the FlexO instance payload is allocated or unallocated. +- The tributary port identifier (TPID) in bits 2 to 8 indicates the tributary port number of the Ethernet client which is being transported in this FlexO instance; Ethernet tributary ports are numbered 1 to 128. The value is set to all-0s when the occupation bit has the value 0 (FlexO instance is unallocated). + +![](f57c7b37d7a05a99618104f390089f03_img.jpg) + +| | | | | | | | | +|-----|------|---|---|---|---|---|---| +| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| OCC | TPID | | | | | | | + +G.709.1(24) + +**Figure 10-8 – Ethernet GMP MSI** + +#### 10.2.3.2 FlexO justification overhead (JC) + +GMP overhead is carried once per 4-frame multi-frame in bytes JC1-JC6. The 14-bit $C_m(t)$ (i.e., m-bit block count value) is carried in bits C1-14 of JC1 and JC2 (C1=MSB, ..., C14=LSB) and the encoded 5-bit $\sum C_{nD}(t)$ (cumulative value of $C_{nD}(t)$ ) is carried in bit D1-D5 of JC4 and JC5 (D1=MSB, ..., D5=LSB). + +$C_m(t)$ shall be protected with a CRC8 (carried in JC3 OH byte) and $\sum C_{nD}(t)$ shall be protected with a CRC3 (carried in the four LSBs of JC6 OH byte). Note that because a set of JC1-JC6 bytes are per 4-frame multi-frame, they appear twice in the 8-frame multi-frame shown in Figure 10-7. + +#### 10.2.3.3 Client status (CSTAT) + +An 8-bit (1 byte) field, as shown in Figure 10-9, is provided for general purpose status indication. + +- Client signal fail (CSF) +- Maintenance (MNT) +- Client local and remote degradates (LD, RD) +- Reserved (RES) + +![](9ff1b32449ea068bba9647d71904bd59_img.jpg) + +| | | | | | | | | | +|------|-----|-----|---|---|-----|----------|----|----| +| Bits | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| | CSF | MNT | | | RES | am
sf | RD | LD | + +G.709.1(24) + +**Figure 10-9 – Ethernet GMP CSTAT field** + +##### 10.2.3.3.1 Client signal fail (CSF) + +The client signal fail (CSF) bit is set to "1" to indicate that an incoming client fault was detected; otherwise it is set to "0". The client signal fail (CSF) bit indicates forward signal fail status detected at the local RX client interface in the downstream direction. The replacement signal for client fault conditions is Ethernet local fault (LF) as defined in [IEEE 802.3] generated using a local clock and shown in Table 10-3. + +##### 10.2.3.3.2 Reserved (RES) + +One bit of the CSTAT byte is reserved for future international standardization as shown in Figure 10-9. This bit is set to "0". + +##### 10.2.3.3.3 Maintenance (MNT) + +Three bits of the CSTAT byte are used for signalling maintenance states. + +- 000 – Normal operation +- 101 – LCK + +NOTE – 100 value is reserved due to FlexOsec squelch pattern. + +A locked (LCK) is a signal sent downstream as an indication that upstream the connection is "locked". The replacement signal for client locked maintenance is Ethernet local fault (LF) as defined in [IEEE 802.3] generated using a local clock. + +##### 10.2.3.3.4 Client degrade indication (LD/RD) + +The 3-bit host link degrade indication field is defined to indicate to the downstream device the quality of the client. This is transparently passed from the client's terminated alignment markers, which are referred to as $am\_sf<0>$ (reserved), $am\_sf<1>$ (remote degrade RD) and $am\_sf<2>$ (local degrade LD). + +These are only applicable to 200GBASE-R, 400GBASE-R and 800GBASE-R clients. These are applied as described in Annex C. + +### 10.2.4 Mapping of y00GBASE-R client into y FlexO instances of a FlexO-ne + +The mapping of an y00GBASE-R signal (with up to $\pm 100$ or $\pm 50$ ppm bit-rate tolerance) into y FlexO payload instances of a FlexO-ne is performed by means of a generic mapping procedure as specified in Annex D of [ITU-T G.709] and Annex B in this Recommendation. + +The y FlexO payload instances of a FlexO-ne are created from a locally generated clock (within the limits specified in Table 8-3), which is independent of the y00GBASE-R signal. + +The y00GBASE-R signal is adapted to the locally generated y FlexO payload instances of a FlexO-ne clock by means of a generic mapping procedure (GMP) as specified in Annex D [ITU-T G.709]. The value of $n$ in $c_n$ and $C_n(t)$ and $C_{nD}(t)$ is specified in Annex B. + +A group of y successive y00GBASE-R 257-bit words is mapped into a group of y successive FlexO payload instances of a FlexO-ne 257-bit words. + +NOTE 1 – The 257-bit word alignment of the y00GBASE-R is preserved through the mapping procedure; e.g., the position of the first 257 bits of the y00GBASE-R is always located after an integer number of 257-bit words from the start of the y FlexO payload instances of a FlexO-ne structure. + +For the case of y00GBASE-R signals, the generic mapping process generates once per y FlexO payload instances of a FlexO-ne multi-frame the $C_m(t)$ and $C_{nD}(t)$ information according to Annex D [ITU-T G.709] and encodes this information in the y FlexO payload instances of a FlexO-ne justification control overhead JC1/JC2/JC3 and JC4/JC5/JC6. For clients which are split across multiple FlexO payload instances of a FlexO-ne the mappers are locked and the JC bytes are replicated and present in all FlexO instances carrying the client. + +The support for n-bit timing information ( $\Sigma C_{nD}$ ) in the JC4/JC5/JC6 OH is required. + +During a signal fail condition of the incoming y00GBASE-R signal, this failed incoming signal will contain the y00GBASE-R replacement signal as specified in Table 10-3. This y00GBASE-R replacement signal is then mapped into the y FlexO payload instances of a FlexO-ne. + +The y 100G streams of a client signal are mapped to the y FlexO payload instances of a FlexO-ne structure as y 100G aligned 257b block streams. The payload area for this mapping consists of the payload of the aligned 4-frame multi-frames of y FlexO instances in ascending IID order. Groups of m consecutive bits of the client are mapped into m bits of the y aligned 4-frame multi-frame payload areas under control of the GMP data/stuff control mechanism. Each group of m in the y aligned 4-frame multi-frame payload areas may carry either m client bits or m stuff bits. The stuff bits shall be transmitted as zeros and shall be ignored on receive. + +The equations and values of the GMP parameters $m$ , $C_{m,nom}$ , $C_{m,min}$ , $C_{m,max}$ , $n$ , $C_{n,nom}$ , $C_{n,min}$ and $C_{n,max}$ for y00GBASE-R client into "y FlexO payload instances of a FlexO-ne" are specified in Table B.1. + +GMP is a positional mapping with non-fixed stuff locations. The stuff locations within the payload are determined using a delta-sigma algorithm based on the $C_m(t)$ value. + +For information only, Table 10-4 shows the location of the "stuff" GMP blocks for a few specific $C_m$ values. + +**Table 10-4 – GMP stuff locations** + +| $C_m$ | locations | +|-------|---------------------------------| +| 10220 | N/A | +| 10219 | 1 | +| 10218 | 1, 5111 | +| 10217 | 1, 3407, 6814 | +| 10216 | 1, 2556, 5111, 7666 | +| 10215 | 1, 2045, 4089, 6133, 8177 | +| 10214 | 1, 1704, 3407, 5111, 6814, 8517 | + +The de-mapping process decodes $C_m(t)$ and $C_{nd}(t)$ from JC1/JC2/JC3 and JC4/JC5/JC6 and interprets $C_m(t)$ and $C_{nd}(t)$ according to Annex B. CRC-8 shall be used to protect against an error in bits 1 to 8 of the JC1, JC2, JC3 signals. CRC-3 shall be used to protect against an error in bits 6 to 8 of JC4, JC5, JC6 signals. + +A group of $y$ successive $y00GBASE-R$ 257-bit words is de-mapped from a group of $y$ successive FlexO payload instances of a FlexO-ne 257-bit blocks. + +During a signal fail condition of the incoming FlexO-ne signal the $y00GBASE-R$ replacement signal pattern as specified in Table 10-3 is generated as a replacement signal for the lost $y00GBASE-R$ signal. + +## 10.3 GMP mapping of OTUCn clients into FlexO-n + +This clause specifies the multiplexing of OTUCni into FlexO-n payload using a client agnostic generic mapping procedure (GMP). + +This OTUCni into FlexO-n payload multiplexing is performed by means of asynchronous mapping of OTUCni into $n_i$ FlexO payload instances using GMP. + +The FlexO-n supports up to $n$ different OTUCni signals. + +A set of $n$ FlexO instances (FlexO-n) may carry multiple OTUCni ( $i = 1..N$ ) signals via GMP. In the most general case, the $n = n_1 + n_2 + \dots + n_N$ OTUC instances of the OTUCni ( $i = 1..N$ ) are mapped to a FlexO-n. For the reordering of FlexO members and deskewing of each OTUCni client after demapping from FlexO-n, see Clause 10.1.4. + +An OTUCni is mapped in order into $n_i$ FlexO instances with ascending IID values. + +### 10.3.1 Distributing OTUCni and combining OTUC instances + +An OTUCn frame structure is specified in clause 11.3 of [ITU-T G.709] and contains $n$ synchronous instances of OTUC frame structures. As shown in Figure 10-10, the OTUCni multiplexing consists of splitting each of the OTUCni frames into $n_i \times$ OTUC instances and then the mapping of each OTUC instance in a FlexO instance under control of a GMP process. The $n_i$ GMP processes associated with one OTUCni may be locked together at the OTUCni to FlexO mapper, or could be operated independently. At the demapper, each GMP process is operated independently. + +Similarly, the OTUCni demultiplexing consists of extracting each OTUC instance from its FlexO instance under control of a GMP process and combining the $n_i \times$ OTUC instances of each OTUCni into the OTUCni. + +![Diagram showing the mapping of multiple OTUCn clients onto FlexO-n. At the top, OTUCn1, OTUCn2, and OTUCnN are shown, each with an SMOH and OTUCn payload. These are mapped to OTUC blocks, which are then mapped to GMP processes (GMP #1 to GMP #n1, GMP #n1+1 to GMP #n1+n2, etc.). These GMP processes are then mapped to FlexO frames (FlexO frame #1 to FlexO frame #n1, FlexO frame #n1+1 to FlexO frame #n1+n2, etc.), which are finally mapped to the FlexO-n payload.](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg) + +G.709.1(24) + +Diagram showing the mapping of multiple OTUCn clients onto FlexO-n. At the top, OTUCn1, OTUCn2, and OTUCnN are shown, each with an SMOH and OTUCn payload. These are mapped to OTUC blocks, which are then mapped to GMP processes (GMP #1 to GMP #n1, GMP #n1+1 to GMP #n1+n2, etc.). These GMP processes are then mapped to FlexO frames (FlexO frame #1 to FlexO frame #n1, FlexO frame #n1+1 to FlexO frame #n1+n2, etc.), which are finally mapped to the FlexO-n payload. + +**Figure 10-10 – Mapping multiple OTUCn clients onto FlexO-n** + +### **10.3.2 FlexO frame and 4-frame multi-frame payload structure** + +The FlexO frame payload area is divided in 256-bit payload blocks (see Figure 10-11). The 256-bit payload blocks are aligned to the start of a FlexO payload area (following AM, EOH and BOH). The FlexO frame payload consists of 2565 256-bit blocks. + +NOTE – There is no fixed stuff in frames 1 to 7 of the FlexO 8-frame multi-frame in this mapping. + +![Diagram of FlexO frame payload structure with 256-bit payload blocks. It shows a grid of 128 rows and 5140 columns. The first 1280 columns are grouped under 'Columns' 1. The first 16 rows are highlighted in yellow. The last row (row 128) has 2565 blocks.](0b3d9fe35da3ee0c88f1420bb9ed7a03_img.jpg) + +G.709.1(24) + +Diagram of FlexO frame payload structure with 256-bit payload blocks. It shows a grid of 128 rows and 5140 columns. The first 1280 columns are grouped under 'Columns' 1. The first 16 rows are highlighted in yellow. The last row (row 128) has 2565 blocks. + +**Figure 10-11 – FlexO frame payload structure with 256-bit payload blocks** + +![Diagram of FlexO frame payload structure in 128-bit block format with 256-bit GMP blocks. It shows a grid of 24 columns (labeled 1 to 24) and 2580 rows (labeled 2561 to 2580). The first 1280 columns are grouped under 'Columns' 1. The first 16 rows are highlighted in yellow. The last row (row 2580) has 2565 blocks.](26e334e61dd059cff029338a2a604d8d_img.jpg) + +G.709.1(24) + +Diagram of FlexO frame payload structure in 128-bit block format with 256-bit GMP blocks. It shows a grid of 24 columns (labeled 1 to 24) and 2580 rows (labeled 2561 to 2580). The first 1280 columns are grouped under 'Columns' 1. The first 16 rows are highlighted in yellow. The last row (row 2580) has 2565 blocks. + +**Figure 10-12 – FlexO frame payload structure in 128-bit block format with 256-bit GMP blocks** + +The FlexO payload 4-frame multi-frame structure with 256-bit payload blocks in the payload area for the mapping of an OTUC client signal is illustrated in Figures 10-13 and 10-14. The payload area consists of 10,260 256-bit blocks. + +![Figure 10-13: FlexO payload 4-frame multi-frame structure with 256-bit payload blocks for the GMP mapping of an OTUC client signal. The diagram shows a grid of columns (1 to 5140) and rows (1 to 128) organized into four multi-frames (00, 01, 10, 11). Each multi-frame contains 128 rows. Row 1 of each multi-frame is highlighted in grey and contains MFAS bits. Rows 2-128 contain payload blocks. The first row of each multi-frame also contains specific bit indices: Row 1 of 00 (1, 2, ..., 15, 16), Row 1 of 01 (2566, 2567, ..., 2580, 2581), Row 1 of 10 (5131, 5132, ..., 5145, 5146), and Row 1 of 11 (7696, 7697, ..., 7710, 7711).](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +Figure 10-13: FlexO payload 4-frame multi-frame structure with 256-bit payload blocks for the GMP mapping of an OTUC client signal. The diagram shows a grid of columns (1 to 5140) and rows (1 to 128) organized into four multi-frames (00, 01, 10, 11). Each multi-frame contains 128 rows. Row 1 of each multi-frame is highlighted in grey and contains MFAS bits. Rows 2-128 contain payload blocks. The first row of each multi-frame also contains specific bit indices: Row 1 of 00 (1, 2, ..., 15, 16), Row 1 of 01 (2566, 2567, ..., 2580, 2581), Row 1 of 10 (5131, 5132, ..., 5145, 5146), and Row 1 of 11 (7696, 7697, ..., 7710, 7711). + +Figure 10-13 – FlexO payload 4-frame multi-frame structure with 256-bit payload blocks for the GMP mapping of an OTUC client signal + +![Figure 10-14: FlexO payload 4-frame multi-frame structure in 128-bit block format with 256-bit payload blocks for the GMP mapping of an OTUC client signal. This diagram is a detailed view of the payload blocks from Figure 10-13, organized by MFAS Block bits [78] (00, 01, 10, 11) and columns (1 to 5140). It shows the mapping of 256-bit payload blocks into 128-bit blocks. The first column of each multi-frame (columns 1, 2561, 5121, 7681) contains MFAS bits. The remaining columns contain payload blocks, with specific bit indices listed for each block. For example, in multi-frame 00, the first payload block (column 2) contains bits 1-7, and the last payload block (column 2560) contains bits 2557-2565.](95e259e8cb3519025066052af263f8c0_img.jpg) + +Figure 10-14: FlexO payload 4-frame multi-frame structure in 128-bit block format with 256-bit payload blocks for the GMP mapping of an OTUC client signal. This diagram is a detailed view of the payload blocks from Figure 10-13, organized by MFAS Block bits [78] (00, 01, 10, 11) and columns (1 to 5140). It shows the mapping of 256-bit payload blocks into 128-bit blocks. The first column of each multi-frame (columns 1, 2561, 5121, 7681) contains MFAS bits. The remaining columns contain payload blocks, with specific bit indices listed for each block. For example, in multi-frame 00, the first payload block (column 2) contains bits 1-7, and the last payload block (column 2560) contains bits 2557-2565. + +Figure 10-14 – FlexO payload 4-frame multi-frame structure in 128-bit block format with 256-bit payload blocks for the GMP mapping of an OTUC client signal + +The FlexO-n payload bit rate is defined in Table 10-5. + +**Table 10-5 – FlexO-n payload bit rates** + +| Interface type | FlexO-n payload nominal bit rate | FlexO-n payload bit-rate tolerance | +|----------------|-----------------------------------------------------|------------------------------------| +| FlexO-n | $n \times 490428/462961 \times 99\,532\,800$ kbit/s | $\pm 20$ ppm | + +NOTE – The nominal FlexO-n payload bit rate is approximately: $n \times 105\,437\,978.660$ kbit/s. The FlexO-n payload bit rate can be derived from the OTUC bit rate as follows: $n \times 513/514 \times 4112/4097 \times \text{OTUC bit rate} = n \times 513/514 \times 4112/4097 \times 239/226 \times 99\,532\,800$ kbit/s + +### 10.3.3 Client mapping specific overhead + +For OTUCn multiplexing, the mapping specific overhead consists of a multiplex structure identifier (MSI) and justification control (JC1-JC6) overhead. The FlexO MSI and JC1-JC6 overhead locations are illustrated in Figure 10-15 and are present in each FlexO instance of the group of $n = n_1 + n_2 + \dots + n_N$ FlexO instances. + +![Figure 10-15 – FlexO multiplex and justification overhead. The diagram shows the structure of FlexO frames, including MFAS bits, BOH columns, and various overhead bytes (JC1-JC6, MSI[x]).](e05122559f56af5699789b7118d8fe87_img.jpg) + +The diagram illustrates the FlexO multiplex and justification overhead structure across multiple frames and columns. + +**MFAS bits [678] frame** and **BOH column** (5 and 6) mapping: + +| MFAS bits [678] frame | BOH column 5 | BOH column 6 | +|-----------------------|--------------|--------------| +| 000 | 1 | | +| 001 | JC4 | JC1 | +| 010 | JC5 | JC2 | +| 011 | JC6 | JC3 | +| 100 | MSI[x] | | +| 101 | JC4 | JC1 | +| 110 | JC5 | JC2 | +| 111 | JC6 | JC3 | + +**Client specific OH bytes for FlexO payload instance #1 to #n** + +**Bit** (1 to 8) mapping for Justification Control (JC) bytes: + +| Bit | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +|-----|-------|-----|-----|-----|-----|-----|----|----| +| JC1 | C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | +| JC2 | C9 | C10 | C11 | C12 | C13 | C14 | II | DI | +| JC3 | CRC-8 | | | | | | | | + +Annotations for JC1-JC3: + +- ← 14-bit $C_m (m=256)$ (pointing to JC1 bytes C1-C8) +- ↑ Decrement indicator (pointing to II bit in JC2) +- ↑ Increment indicator (pointing to DI bit in JC2) + +**Bit** (1 to 8) mapping for Justification Control (JC) bytes (continued): + +| Bit | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +|-----|---|-----|---|---|---|-------|----|-----| +| JC4 | | RES | | | | D1 | D2 | D3 | +| JC5 | | RES | | | | D4 | D5 | RES | +| JC6 | | RES | | | | CRC-3 | | | + +Annotation for JC4-JC6: ← Client specific 5-bit $\Sigma C_{gp}$ (pointing to D1-D5 bits) + +**MSI[x]** structure: + +| Bit | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +|--------|------|------|---|---|---|---|---|---| +| MSI[x] | Occ. | TPID | | | | | | | + +Legend for MSI[x]: + +- 0: Unallocated +- 1: Allocated + +Legend for TPID: + +- 000 000: Tributary port #1 +- 000 001: Tributary port #2 +- 000 010: Tributary port #3 +- 111 111: Tributary port #128 + +NOTE – $x = 1..n$ + +G.709.1(24) + +Figure 10-15 – FlexO multiplex and justification overhead. The diagram shows the structure of FlexO frames, including MFAS bits, BOH columns, and various overhead bytes (JC1-JC6, MSI[x]). + +**Figure 10-15 – FlexO multiplex and justification overhead** + +#### 10.3.3.1 FlexO multiplex structure identifier (MSI) + +The FlexO multiplex structure identifier (MSI) overhead, which encodes the OTUC multiplex structure in the FlexO-n payload is located in frame 5, in overhead byte 5 in all n FlexO frames, as illustrated in Figure 10-15. The MSI indicates the OTUC content of each FlexO instance payload. One byte is used for each FlexO instance. + +- The FlexO occupation bit 1 indicates if the FlexO instance payload is allocated or unallocated. +- The tributary port identifier in bits 2 to 8 indicates the tributary port number of the OTUCni of which an OTUC instance is being transported in this FlexO instance; for the case of a OTUCni carried in two or more FlexO instances a flexible assignment of tributary port to FlexO instance is possible. OTUCni tributary ports are numbered 1 to N. The value is set to all-0s when the occupation bit has the value 0 (FlexO instance is unallocated). + +#### 10.3.3.2 FlexO justification overhead + +The FlexO justification control overhead (JOH), which carry GMP justification control overhead, is located in frames 2, 3, 4, 6, 7 and 8 in overhead bytes 5 and 6 in all $n$ FlexO frames, as illustrated in Figure 10-15. It consists of two groups of six bytes of justification control: JC1, JC2, JC3 and JC4, JC5, JC6. + +The JC1, JC2 and JC3 bytes consist of a 14-bit $C_m(t)$ field (bits C1 (MSB), C2, ..., C14 (LSB)), a 1-bit increment indicator (II) field, a 1-bit decrement indicator (DI) field and a 8-bit CRC-8 field which contains an error check code over the JC1, JC2 and JC3 bytes. + +The JC4, JC5 and JC6 bytes consist of a 5-bit $\Sigma C_{nD}$ field (bits D1, D2, ..., D5), a 3-bit CRC-3 field which contains an error check code over bits 6 to 8 in the JC4, JC5 and JC6 fields and sixteen bits reserved for future international standardization (RES). + +The value of 'm' in $C_m$ is 256. + +The value of 'n' represents the timing granularity of the GMP $C_n$ parameter, which is also present in $\Sigma C_{nD}$ . The value of $n$ is 8. + +The value of $C_m$ controls the distribution of groups of two 128-bit OTUC data blocks into 256-bit GMP blocks in the FlexO payload. Refer to Annex D of [ITU-T G.709] and Annex B for further specification of this process. + +The value of $\Sigma C_{nD}$ provides additional 'n'-bit timing information, which is necessary to control the jitter and wander performance experienced by the OTUC signal. + +The value of $C_n$ (i.e., number of client n-bit data entities per FlexO payload 4-frame multi-frame) is computed as follows: $C_n(t) = m/n \times C_m(t) + (\Sigma C_{nD}(t) - \Sigma C_{nD}(t-1))$ . Note that the value $C_{nD}$ is effectively an indication of the amount of data in the mapper's virtual queue that it could not send during that multi-frame due to it being less than a 256-bit word. For the case where the value of $\Sigma C_{nD}$ in a multi-frame 't' is corrupted, it is possible to recover from such error in the next multi-frame 't+1'. + +### 10.3.4 Mapping of OTUC $_n$ into $n_i$ FlexO instances of a FlexO-n + +The mapping of an OTUC $_n$ signal (with up to $\pm 20$ ppm bit-rate tolerance) into $n_i$ FlexO instances payload is performed by means of a generic mapping procedure. + +The $n_i$ FlexO payload instances are created from a locally generated clock (within the limits specified in Table 8-3), which is independent of the OTUC $_n$ signal. + +Specifically, an OTUC instance of an OTUC $_n$ is mapped into a FlexO instance payload of the $n_i$ FlexO instances payload. The bit rate of the OTUC instance is $1/n_i$ the bit rate of the OTUC $_n$ client specified in [ITU-T G.709] Table 7 1. + +An OTUC signal is adapted to the locally generated FlexO instance payload clock by means of a generic mapping procedure (GMP) as specified in Annex D [ITU-T G.709]. The value of $n$ in $c_n$ and $C_n(t)$ and $C_{nD}(t)$ is specified in Annex B. + +An OTUC 32-byte (256-bit) word is mapped into a FlexO payload instance 32-byte (256-bit) word. + +NOTE 1 – The 32-byte word alignment of the OTUC is preserved through the mapping procedure; e.g., the position of the first 32 bytes of the OTUC is always located after an integer number of 32-byte words from the start of the FlexO payload instance structure. + +For the case of OTUC signals, the generic mapping process generates once per FlexO payload instance multi-frame the $C_m(t)$ and $C_{nD}(t)$ information according to Annex D [ITU-T G.709] and encodes this information in the FlexO payload instance justification control overhead JC1/JC2/JC3 and JC4/JC5/JC6. The de-mapping process decodes $C_m(t)$ and $C_{nD}(t)$ from JC1/JC2/JC3 and JC4/JC5/JC6 and interprets $C_m(t)$ and $C_{nD}(t)$ according to Annex B. CRC-8 shall be used to protect + +against an error in bits 1 to 8 of the JC1, JC2, JC3 signals. CRC-3 shall be used to protect against an error in bits 6 to 8 of JC4, JC5, JC6 signals. + +During a signal fail condition of the incoming OTUCn signal, this failed incoming signal will contain the OTUCn-AIS signal as specified in clause 16.4.2 of [ITU-T G.709]. This OTUCn-AIS is then mapped into the $n_i$ FlexO instances payload. + +An OTUC 32-byte word is de-mapped from a FlexO payload instance 32-byte block. + +The equations and values of GMP parameters $m$ , $C_{m,nom}$ , $C_{m,min}$ , $C_{m,max}$ , $n$ , $C_{n,nom}$ , $C_{n,min}$ and $C_{n,max}$ for OTUCn client into FlexO- $n_i$ payload area are specified in Table B.1. + +#### 10.3.4.1 Mapping OTUC into FlexO instance payload + +Groups of 32-byte/256-bit words of the OTUC signal are mapped into a 32-byte block of the FlexO instance payload area under control of the GMP data/stuff control mechanism. Each 32-byte block in the FlexO instance payload area may either carry an OTUC 32-byte word, or carry a stuff 32-byte word. The value of the stuff bytes is set to all-0s. + +The 32-byte blocks in the FlexO instance payload area are numbered from 1 to 10260. + +The FlexO instance payload 32-byte numbering for GMP 32-byte ( $m$ -bit) blocks is illustrated in Figures 10-12 and 10-13. + +## 10.4 FlexO- $n$ group alignment and deskewing + +### 10.4.1 Alignment and deskewing of OTUCn clients + +FlexO members are identified within a FlexO- $n$ group and reordered using GID, MAP and IID FlexO BOH field. + +For OTUCn BMP and GMP mappings defined in clauses 10.1 and 10.3, deskewing in the sink process is performed between OTUC frames within the group, using OTUC FAS as specified in [ITU-T G.709]. + +The OTUC frame skew requirements are intended to account for variations due to digital mapping and cable lengths. The skew tolerance requirements are specified in [ITU-T G.709.3], [ITU-T G.709.5] and [ITU-T G.709.6]. + +During a signal fail condition of the incoming FlexO- $n$ signal or if the OTUCn deskewing has failed, the OTUCn-AIS pattern as specified in clause 16.4.2 [ITU-T G.709] is generated as a replacement signal for the lost OTUCn signal. + +## 10.5 FlexO payload PRBS test pattern + +A framed FlexO PRBS test pattern is used for validating FlexO- $x(e)$ - interfaces through links and regens. The required PRBS31 is per [IEEE 802.3] with the initial generator state (see Figure 10-16) being all 1's. + +- The PRBS polynomial pattern is inserted per FlexO instance, replicated in all instances on a FlexO- $x(e)$ - interface. +- The PRBS pattern will be identified by a unique payload type identifier as shown in Table 9-1. +- The PRBS in the source is inserted in the full payload area shown in Figure 8-1. Stuffing or padding used by mapping procedures is ignored (overwritten) when PRBS is used. +- The PRBS in the sink is monitored from the FlexO payload area. The PRBS checker shall recover and verify the PRBS31 sequence. + +![Diagram of FlexO PRBS generator showing a sequence of state elements S0 through S30 with a feedback loop and an output tap.](e8e818455bb0d1a6153299a388b94868_img.jpg) + +The diagram illustrates a PRBS31 generator. It consists of a series of state elements labeled S0, S1, S2, followed by an ellipsis, then S27, S28, S29, and S30. The elements are connected in a linear sequence from left to right. A feedback loop originates from the output of state element S30, passes through a summation node (represented by a circle with a '+' sign), and then branches: one path goes back to the input of state element S0, and the other path goes through an inverter (represented by a triangle with a small circle at its tip) to produce the 'PRBS31 pattern output'. The text 'G.709.1(24)' is located in the bottom right corner of the diagram area. + +Diagram of FlexO PRBS generator showing a sequence of state elements S0 through S30 with a feedback loop and an output tap. + +**Figure 10-16 – FlexO PRBS** + +### 10.5.1 Client mapping specific overhead + +The client mapping specific overhead shown in Figure 9-2 is not used for PRBS test pattern and reserved. + +# Annex A + +## FlexOsec encryption and authentication + +(This annex forms an integral part of this Recommendation.) + +This annex specifies encryption and authentication of fixed-length FlexO frame structures. It contains specific authentication and encryption process details for the different cipher suite types (profiles). + +A cipher suite type is an interoperable specification of cryptographic algorithms together with the values of parameters (e.g., key size) to be used by those algorithms. Specification of the cryptographic functions required by FlexOsec in terms of cipher suite types increase interoperability by providing a clear default and a limited number of alternatives. + +## A.1 GCM-AES-256 frame payload encryption + +The GCM-AES-256 cipher suite corresponds to CST value of 000001 as shown in Table 9-3. This profile is based on cryptographic algorithms and processes as defined in [NIST SP 800-38D]. + +In this cipher suite type, the FlexO frame payload is encrypted for confidentiality as shown in Figure A.1. The FlexO frame payload along with BOH and a subset of EOH are authenticated for integrity as shown in Figure A.2. + +In the FlexOsec scheme, confidentiality and integrity are applied individually per FlexO instance. The frame format discussed in this annex is prior to FEC adaptation and FlexO-x interface interleaving. + +### A.1.1 GCM-AES-256 confidentiality (encryption) + +The bits in the FlexO frame payload area are encrypted prior to transmission for cases where confidentiality on the interface is required, as illustrated in Figure A.1. These bits correspond to the FlexO frame payload area and are excluding AM, EOH and BOH fields. For the purpose of FlexOsec application, the FlexO frame structure can be represented as $5140 \times 128$ -bit fixed-length blocks. An alternate representation using 128-bit blocks is shown in Figure A.2. + +![Diagram of FlexO frame encryption structure showing columns and rows. Columns are numbered 1, 480, 960, 1280, ..., 5140. Rows are numbered 1, 2, 3, ..., 128. Row 1 contains AM, EOH, and BOH fields. The remaining area is the Payload area. The total width is 5140 bits.](762a17cd79880dbca172bcbbe9375223_img.jpg) + +The diagram illustrates the FlexO frame structure as a grid of 128 rows and 5140 columns. The columns are labeled at the top: 1, 480, 960, 1280, ..., 5140. The rows are labeled on the left: 1, 2, 3, ..., 128. Row 1 is divided into three segments: AM (columns 1 to 480), EOH (columns 481 to 960), and BOH (columns 961 to 1280). The remaining part of the frame, from column 1281 to 5140 and from row 2 to 128, is a large blue rectangle labeled 'Payload area'. A double-headed arrow at the bottom indicates the total width is '5140 bits'. The reference 'G.709.1(24)' is in the bottom right corner. + +Diagram of FlexO frame encryption structure showing columns and rows. Columns are numbered 1, 480, 960, 1280, ..., 5140. Rows are numbered 1, 2, 3, ..., 128. Row 1 contains AM, EOH, and BOH fields. The remaining area is the Payload area. The total width is 5140 bits. + +Figure A.1 – FlexO frame encryption + +![Figure A.2: FlexO frame encryption (128-bit representation). This diagram shows a sequence of 128-bit blocks. The first block is labeled 'Block #' and contains sub-fields: EOH, BOH, and BOH. Subsequent blocks are numbered 1 through 24. The diagram then shows a series of blocks with indices 2561 through 2580, and another series with indices 5123 through 5140. A horizontal double-headed arrow below the blocks is labeled 'FlexO frame 5140 x 128 bits'. The reference 'G.709.1(24)' is in the bottom right corner.](c1df61cc3717e878a48e530218403403_img.jpg) + +Figure A.2: FlexO frame encryption (128-bit representation). This diagram shows a sequence of 128-bit blocks. The first block is labeled 'Block #' and contains sub-fields: EOH, BOH, and BOH. Subsequent blocks are numbered 1 through 24. The diagram then shows a series of blocks with indices 2561 through 2580, and another series with indices 5123 through 5140. A horizontal double-headed arrow below the blocks is labeled 'FlexO frame 5140 x 128 bits'. The reference 'G.709.1(24)' is in the bottom right corner. + +**Figure A.2 – FlexO frame encryption (128-bit representation)** + +### A.1.2 GCM-AES-256 integrity (authentication) + +The bits in the FlexO frame payload area, BOH and subset of the EOH are authenticated prior to transmission for cases where the integrity of the information on the interface is required, as illustrated in Figure A.3. An alternate representation using 128-bit blocks is shown in Figure A.4. The authentication starts at bit 769 (in the EOH), which corresponds to the 7th 128-bit word, and runs until the end of the frame. + +![Figure A.3: FlexO frame authentication. This diagram shows a grid with 'Columns' at the top (1, 480, 768, 960, 1280, ..., 5140) and 'Rows' on the left (1, 2, 3, ..., 128). The first row contains three segments: 'AM' (from column 1 to 480), 'EOH' (from column 480 to 768), and 'BOH' (from column 768 to 1280). The rest of the grid is a large green area labeled 'Payload area'. A horizontal double-headed arrow at the bottom is labeled '5140 bits'. The reference 'G.709.1(24)' is in the bottom right corner.](036ceaf207a7b289ca76e160892eb724_img.jpg) + +Figure A.3: FlexO frame authentication. This diagram shows a grid with 'Columns' at the top (1, 480, 768, 960, 1280, ..., 5140) and 'Rows' on the left (1, 2, 3, ..., 128). The first row contains three segments: 'AM' (from column 1 to 480), 'EOH' (from column 480 to 768), and 'BOH' (from column 768 to 1280). The rest of the grid is a large green area labeled 'Payload area'. A horizontal double-headed arrow at the bottom is labeled '5140 bits'. The reference 'G.709.1(24)' is in the bottom right corner. + +**Figure A.3 – FlexO frame authentication** + +![Figure A.4: FlexO frame authentication (128-bit representation). This diagram shows a sequence of 128-bit blocks. The first block is labeled 'Block #' and contains sub-fields: EOH, BOH, and BOH. Subsequent blocks are numbered 1 through 24. The diagram then shows a series of blocks with indices 2561 through 2580, and another series with indices 5123 through 5140. A horizontal double-headed arrow below the blocks is labeled 'FlexO frame 5140 x 128 bits'. The reference 'G.709.1(24)' is in the bottom right corner.](683f755e8456c884716de4fce48c7e63_img.jpg) + +Figure A.4: FlexO frame authentication (128-bit representation). This diagram shows a sequence of 128-bit blocks. The first block is labeled 'Block #' and contains sub-fields: EOH, BOH, and BOH. Subsequent blocks are numbered 1 through 24. The diagram then shows a series of blocks with indices 2561 through 2580, and another series with indices 5123 through 5140. A horizontal double-headed arrow below the blocks is labeled 'FlexO frame 5140 x 128 bits'. The reference 'G.709.1(24)' is in the bottom right corner. + +**Figure A.4 – FlexO frame authentication (128-bit representation)** + +An authentication tag (AT) is created using algorithms specified in clause A.1.2, with 128-bit words from the FlexO instance #i frame #j. The AT is then inserted in the next EOH of FlexO instance #i frame #j+1. The authentication tag is unique to each FlexO instance. + +![Diagram illustrating FlexO AT insertion. It shows two frame structures. The top frame has a header with AM, EOH, and BOH fields, followed by a large green 'Payload area'. An arrow points from the end of the payload area to a green box labeled 'AT'. The bottom frame has a similar header (AM, EOH, BOH) and a white 'Payload area'. An arrow points from the 'AT' box in the top frame to the 'EOH' field in the bottom frame, indicating the insertion of the authentication tag into the next frame's overhead.](38cbce07f83fba6d5a7c46605bd5743f_img.jpg) + +Diagram illustrating FlexO AT insertion. It shows two frame structures. The top frame has a header with AM, EOH, and BOH fields, followed by a large green 'Payload area'. An arrow points from the end of the payload area to a green box labeled 'AT'. The bottom frame has a similar header (AM, EOH, BOH) and a white 'Payload area'. An arrow points from the 'AT' box in the top frame to the 'EOH' field in the bottom frame, indicating the insertion of the authentication tag into the next frame's overhead. + +G.709.1(24) + +**Figure A.5 – FlexO AT insertion** + +In the process flow, some values in the FlexOsec overhead are inserted after AT calculation (algorithm) in the source functions and before in the sink functions. Some OH values will be assumed as all-0s for the AT algorithms and these are reflected in Table A.1. Figure A.5 shows FlexO AT insertion. + +**Table A.1 – FlexOsec OH AT calculation** + +| FlexOsec OH field | Tag calculation | Note | +|-------------------------|-----------------------------|------------------------------------| +| Authentication tag (AT) | Not part of tag calculation | | +| Frame number (FN) | Use FN value | | +| Key index (KI) | Use KI value | | +| Cipher suite type (CST) | Use CST value | | +| KCC | All-0s | KCC inserted after tag calculation | +| Reserved (RES) | All-0s | | + +Since the AT value of a current frame (n) is presented in the following frame (n+1), buffering of a FlexO frame could optionally be required for some applications that discard frames that have failed integrity check (authentication failures). The individual frames can be optionally replaced with a repeating SquelchText = 0x04 byte pattern replacing the area covered by authentication as shown in Figure A.3. Figure A.6 shows per instance FlexO processing. + +![Diagram illustrating per instance FlexO processing. It shows 'n FlexO instances' stacked vertically. Each instance has a header with AM, EOH, and BOH fields, followed by a large 'Payload area'. Arrows from the payload areas point to 'AT' (Authentication Tag) blocks. The diagram is labeled G.709.1(24).](12c19090355e19922e23044633b9d1ea_img.jpg) + +Diagram illustrating per instance FlexO processing. It shows 'n FlexO instances' stacked vertically. Each instance has a header with AM, EOH, and BOH fields, followed by a large 'Payload area'. Arrows from the payload areas point to 'AT' (Authentication Tag) blocks. The diagram is labeled G.709.1(24). + +**Figure A.6 – Per instance FlexO processing** + +### A.1.3 IV construction + +The 96-bit initial vector for this cipher suite type is based on deterministic construction as defined in clause 8.2.1 of [NIST SP 800-38D]. In order to promote interoperability for the default IV length of 96 bits, the leading (i.e., leftmost) 32 bits of the IV hold a user configurable fixed identifier and the trailing (i.e., rightmost) 64 bits hold the invocation field, which is the frame number (FN). + +NOTE – The construction described in this clause meets the total number of invocation requirements as specified in clause 8.3 of [NIST SP 800-38D]. + +### A.1.4 GCM-AES-256 algorithms + +The authenticated encryption and authenticated decryption algorithms for this cipher suite type are based on the GCM specifications in clause 7 of [NIST SP 800-38D]. These are referred to as algorithms 4 and 5, for the authenticated encryption and authenticated decryption functions, respectively. The specifications include the inputs, the outputs, the steps of the algorithm, diagrams, and summaries. The GCM-AES-256 parameters are listed in Table A.2. + +**Table A.2 – GCM-AES-256 parameters** + +| Parameter | Name | Length | +|-----------|----------------------------------------------------------|-------------------------------| +| C | CipherText | 656640 bits (5130 × 128 bits) | +| P | PlainText | 656640 bits (5130 × 128 bits) | +| A | Additional authenticated data | 512 bits (4 × 128 bits) | +| T | Authentication tag (referred to as AT in recommendation) | 128 bits | +| K | Key | 256 bits | +| IV | Initial vector | 96 bits | + +Figure A.7 shows how the FlexO frame bits are processed with respective cryptographic algorithms. There are three inputs into the NIST authenticated encryption algorithm referred to as algorithm 4: J0, AAD and P (plaintext). The first bits transmitted are the leftmost bits in the figure. + +| | | | | | | | | | | | | | | | | | | +|---|-------------------------|--|--|--|-------------------|--|--|--|--|--|--|--|------|------|------|-----------|-----| +| 1 | 32-bit fixed identifier | | | | 64-bit invocation | | | | | | | | 0x00 | 0x00 | 0x00 | 000000001 | 128 | +| | | | | | FN[1 : 64] | | | | | | | | | | | | | + +EOH byte 41 +EOH byte 48 + +| | | | +|---|---------------------------------------|-----| +| 1 | 128-bit additional authenticated data | 128 | +| | Portions EOH and BOH | | + +e.g., EOH byte 37 + e.g., EOH byte 53 + e.g., BOH byte 9 + e.g., BOH byte 25 + +EOH byte 52 + BOH byte 8 + BOH byte 24 + EOH byte 40 + +| | | | +|---|-------------------------|-----| +| 1 | 128-bit plaintext | 128 | +| | FlexO payload [1 : 128] | | + +Payload byte 1 + +Payload byte 16 +G.709.1(24) + +**Figure A.7 – FlexOsec bit ordering** + +44      **Rec. ITU-T G.709.1 (03/2024)** + +# Annex B + +## Applying generic mapping procedure principles in a FlexO-n(e) + +(This annex forms an integral part of this Recommendation.) + +This annex complements Annex D in [ITU-T G.709] with FlexO specific aspects. It presents application principles of GMP within the FlexO cases when a client is mapped into a FlexO-n(e) payload. + +## B.1 Applying GMP in a FlexO-n(e) + +Clauses 10.2 and 10.3 of this Recommendation specify GMP as the asynchronous generic mapping method for the mapping of Ethernet and OTN client signals into a FlexO-n(e). Asynchronous mappings have a timing granularity $n$ as shown in Table B.1. + +### B.1.1 Mapping granularity + +#### 257y-bit granularity mapping + +Clause 10.2 of this Recommendation specifies that the mapping of Ethernet bits into the payload of an FlexO-ne is performed with $257 \times y$ -bit (257y-bit) granularity, where $y$ is the number of FlexO payload instances occupied by the client signal, as shown in Table D.1 of [ITU-T G.709]. The value of $m$ discussed in clause D.2 of [ITU-T G.709] is $257 \times y$ . The remaining $C_{nD}(t)$ data entities are signalled in the justification overhead as additional timing/phase information. + +The corresponding $c_m$ , $C_m(t)$ , $c_{nD}$ and $C_{nD}(t)$ values can be calculated using equations D-12 through D-15 in [ITU-T G.709], with $m = 257 \times y$ . + +The FlexO 257y-bit granularity uses the 14-bit $C_m(t)$ described in clause B.1.2.1, with the corresponding 5-bit $\sum C_{nD}(t)$ described in clause B.1.3.1. + +#### 256ni-bit/32ni-byte granularity mapping + +Clause 10.3 of this Recommendation specifies that the mapping of OTUC $n_i$ bits into the payload of $n_i$ FlexO instances of an FlexO-n is performed with 256-bit (32-byte) granularity per OTUC/FlexO instance, as shown in Table B.1. The value of $m$ discussed in clause D.2 of [ITU-T G.709] is 256. The remaining $C_{nD}(t)$ data entities are signalled in the justification overhead as additional timing/phase information. + +The corresponding $c_m$ , $C_m(t)$ , $c_{nD}$ and $C_{nD}(t)$ values can be calculated using equations D-12 through D-15 in [ITU-T G.709], with $m = 256$ . + +The FlexO 32i-byte granularity uses the 14-bit $C_m(t)$ described in the example below in clause D.3.2.2 of [ITU-T G.709] with the corresponding 5-bit $\sum C_{nD}(t)$ described in clause D.3.3.2 of [ITU-T G.709]. + +#### Values of GMP parameters for FlexO servers + +The values for $n$ , $m$ , $f_{client}$ , $f_{server}$ , $T_{server}$ , $B_{server}$ , $O_{server}$ , $P_{server}$ , $f_{n,server}$ , $P_{n,server}$ , $P_{m,server}$ and $\sum C_{nD}$ are specified in Table B.1. + +**Table B.1 – FlexO-n(e) GMP parameters** + +| GMP parameter | Equations | y00GBASE-R into y FlexO payload instances of a FlexO-ne | OTUC into FlexO instance payload | +|-----------------------------|-----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------| +| $n$ | | $y \times 8.03125$
100GBASE-R: $8.03125 \times 1 = 8.03125$
200GBASE-R: $8.03125 \times 2 = 16.0625$
400GBASE-R: $8.03125 \times 4 = 32.125$
800GBASE-R: $8.03125 \times 8 = 64.25$ | 8 | +| $m$ | | $m = 257 \times y$
100GBASE-R: $257 \times 1 = 257$
200GBASE-R: $257 \times 2 = 514$
400GBASE-R: $257 \times 4 = 1028$
800GBASE-R: $257 \times 8 = 2056$ | $m = 256$ | +| $f_{client}$ | | Ethernet nominal bit rate (Table 10-2)
100GBASE-R: 100,384,497,642.517 bit/s
200GBASE-R: $2 \times 100,385,723,114.014$ bit/s
400GBASE-R: $4 \times 100,385,723,114.014$ bit/s
800GBASE-R: $8 \times 100,385,723,114.014$ bit/s | OTUC nominal bit rate ( $1/n_i \times$ OTUCn i bit rate specified Table 7-1 [ITU-T G.709])

105,258,138,053.097 bit/s | +| $f_{client\_tolerance}$ | | Ethernet tolerance (Table 10-2)
100GBASE-R: 100 ppm
200GBASE-R: 100 ppm
400GBASE-R: 100 ppm
800GBASE-R: 50 ppm | OTUCn i tolerance (Table 7-1 of [ITU-T G.709])

20 ppm | +| $f_{server}$ | | FlexO-ne nominal bit rate (Table 8-1)
$y \times 100,622,438,327.432$ bit/s | FlexO nominal bit rate (Table 8-1)
105,643,510,782.118 | +| $f_{server\_tolerance}$ | | FlexO-ne tolerance (Table 8-1)
20 ppm | FlexO tolerance (Table 8-1)
20 ppm | +| $T_{server}$ | | FlexO-ne 4-frame period (Table 8-2)
$\sim 26.155 \mu\text{s}$ | FlexO 4-frame period (Table 8-2)
$\sim 24.911 \mu\text{s}$ | +| $B_{server}$ | | $y \times 10240 \times 257$ bits =
$y \times 2,631,680$ bits | $10280 \times 256$ bits =
2,631,680 bits | +| $O_{server}$ | | $y \times 20 \times 257$ bits =
$y \times 5,140$ bits | $20 \times 256$ bits =
5120 bits | +| $P_{server} = P_{n,server}$ | | $10220 \times 257$ bits / $8.03125 = 10220 \times 32 = 327,040$ n-bits | $10260 \times 256$ bits / $n = 10260 \times 32 = 328,320$ n-bits | +| $f_{p,server}$ | | $y \times$ FlexO payload instances bit rate and tolerance (Table 10-1)
$y \times 100,425,910,127.574$ bit/s | FlexO payload bit rate and tolerance (Table 10-5)
105,437,978,659.973 bit/s | +| $P_{m,server}$ | | 10220 m-bits | 10260 m-bits | +| $\Sigma C_{nD}$ range | | 0 to +31 | 0 to +31 | + +**Table B.1 – FlexO-n(e) GMP parameters** + +| GMP parameter | Equations | y00GBASE-R into y FlexO payload instances of a FlexO-ne | OTUC into FlexO instance payload | +|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------|----------------------------------| +| $C_{m,nom}$ | $C_{m,nom} = \left( \frac{f_{client\_nom} \times P_{m,server}}{f_{p,server\_nom}} \right)$ | 100GBASE-R: 10 215.785
y00GBASE-R: 10 215.910 (y = 2,4,8) | 10242.5 | +| $C_{m,min}$
(note) | $C_{m,min} = C_{m,nom} \times \left( \frac{1 - f_{client\_tolerance}}{1 + f_{p,server\_tolerance}} \right)$
$C_{m,min} = \lfloor C_{m,min} \rfloor$ | 100GBASE-R: 10 214.559
y00GBASE-R: 10 214.684 (y = 2,4)
800GBASE-R: 10 215.195 | 10 242.090 | +| $C_{m,max}$
(note) | $C_{m,max} = C_{m,nom} \times \left( \frac{1 + f_{client\_tolerance}}{1 - f_{p,server\_tolerance}} \right)$
$C_{m,max} = \lceil C_{m,max} \rceil$ | 100GBASE-R: 10 217.011
y00GBASE-R: 10 217.136 (y = 2,4)
800GBASE-R: 10 216.625 | 10 242.910 | +| $C_{n,nom}$ | $C_{n,nom} = \left( \frac{f_{client\_nom} \times P_{n,server}}{f_{p,server\_nom}} \right)$ | 100GBASE-R: 326 905.139
y00GBASE-R: 326 909.130 (y = 2,4,8) | 327 760 | +| $C_{n,min}$
(note) | $C_{n,min} = C_{n,nom} \times \left( \frac{1 - f_{client\_tolerance}}{1 + f_{p,server\_tolerance}} \right)$
$C_{n,min} = \lfloor C_{n,min} \rfloor$ | 100GBASE-R: 326 865.9111
y00GBASE-R: 326 869.902 (y = 2,4)
800GBASE-R : 326 886.247 | 327 746.890 | +| $C_{n,max}$
(note) | $C_{n,max} = C_{n,nom} \times \left( \frac{1 + f_{client\_tolerance}}{1 - f_{p,server\_tolerance}} \right)$
$C_{n,max} = \lceil C_{n,max} \rceil$ | 100GBASE-R: 326 944.368
y00GBASE-R: 326 948.360 (y = 2,4)
800GBASE-R : 327 773.111 | 327 773.111 | + +NOTE – $C_{m,min}$ , $C_{n,min}$ , $C_{m,max}$ and $C_{n,max}$ values represent the boundaries of client and server payload ppm offset combinations (i.e., min. client/max. payload and max. client/min. payload). In steady state, given instances of client and server payload offset combinations should not result in generated $C_m$ and $C_n$ values throughout this range but rather should be within as small a range as possible. + +Under transient ppm offset conditions (e.g., replacement signal to normal signal), it is possible that $C_n$ and $C_m$ values outside the range $C_{n,min}$ to $C_{n,max}$ and $C_{m,min}$ to $C_{m,max}$ may be generated and a GMP de-mapper should be tolerant of such occurrences. + +### B.1.2 FlexO $C_m(t)$ encoding and decoding + +$C_m(t)$ is encoded in the FlexO justification control bytes JC1, JC2 and JC3 specified in clause 10.2.3 and 10.3.3 of this Recommendation for the 14-bit count. + +#### B.1.2.1 FlexO $C_m(t)$ encoding and decoding for FlexO-ne and FlexO-n + +The encoding of $C_m(t)$ into bytes JC1 and JC2 for FlexO-n(e) is defined using the 14-bit count field of Table B.2. An "I" entry in the table indicates an inversion of that bit. A CRC-8 in JC3 verifies whether the transmitted $C_m(t)$ value has been received correctly. + +**Table B.2 – 14-bit $C_m(t)$ increment and decrement indicator patterns** + +| C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | C9 | C10 | C11 | C12 | C13 | C14 | II | DI | Change | +|--------------------------------------------------------------------------------|----|----|----|----|----|----|----|----|-----|-----|-----|-----|-----|----|----|--------------------| +| U | U | U | U | U | U | U | U | U | U | U | U | U | U | 0 | 0 | 0 | +| I | U | I | U | I | U | I | U | I | U | I | U | I | U | 1 | 0 | +1 | +| U | I | U | I | U | I | U | I | U | I | U | I | U | I | 0 | 1 | -1 | +| U | I | I | U | U | I | I | U | U | I | I | U | U | I | 1 | 0 | +2 | +| I | U | U | I | I | U | U | I | I | U | U | I | I | U | 0 | 1 | -2 | +| binary value | | | | | | | | | | | | | | 1 | 1 | More than
+2/-2 | +| NOTE:
– I indicates inverted $C_j$ bit
– U indicates unchanged $C_j$ bit | | | | | | | | | | | | | | | | | + +The CRC-8 located in JC3 is calculated over the JC1 and JC2 bits. The CRC-8 uses the $G(x) = x^8 + x^3 + x^2 + 1$ generator polynomial, and is calculated as follows: + +- 1) The JC1 and JC2 octets are taken in network octet order, most significant bit first, to form a 16-bit pattern representing the coefficients of a polynomial $M(x)$ of degree 15. +- 2) $M(x)$ is multiplied by $x^8$ and divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ of degree 7 or less. +- 3) The coefficients of $R(x)$ are considered to be an 8-bit sequence, where $x^7$ is the most significant bit. +- 4) This 8-bit sequence is the CRC-8 where the first bit of the CRC-8 to be transmitted is the coefficient of $x^7$ and the last bit transmitted is the coefficient of $x^0$ . + +The demapper process performs steps 1-3 in the same manner as the mapper process, except that here, the $M(x)$ polynomial of step 1 includes the CRC bits of JC3, resulting in $M(x)$ having degree 23. In the absence of bit errors, the remainder shall be 0000 0000. + +A parallel logic implementation of the source CRC-8 associated with the 14-bit $C_m(t)$ encoding of Table B.2 is illustrated in Appendix VI of [ITU-T G.709]. + +Figure D.7 in [ITU-T G.709] is applied to the GMP sink synchronization for the 14-bit $C_m(t)$ . When $II \neq DI$ in frame $i$ , the Hunt state is determined by the values of the II and DI bits and the count least significant bit (LSB) (C14) in frame $i$ . When frame $i+1$ is received, Figure D.7 in [ITU-T G.709] synchronization state machine "S" state interpretation associated with the 14-bit count field is specified in Table B.3. + +**Table B.3 – "S" state interpretation (see Figure D.7) with 14-bit $C_m$** + +| S state | Interpretation/Action | +|---------|-------------------------------------------------------------------------------------------------| +| S+2 | Count = C1-C14 after inverting C2, C3, C6, C7, C10, C11, & C14; Increment +2 for the next frame | +| S+1 | Count = C1-C14 after inverting C1, C3, C5, C7, C9, C11, & C13; Increment +1 for the next frame | +| S-1 | Count = C1-C14 after inverting C2, C4, C6, C8, C10, C12, & C14; Decrement -1 for next frame | +| S-2 | Count = C1-C14 after inverting C1, C4, C5, C8, C9, C12, C13; Decrement -2 for next frame | + +When synchronized, the GMP sink uses the updated $C_m(t)$ value to extract the client data from the next FlexO-n tributary unit frame as described above in clause D.2.2 in [ITU-T G.709], interpreting the received JC octets according to the inversion patterns of Table B.2. + +### B.1.3 FlexO $\Sigma C_{nd}(t)$ encoding and decoding + +#### B.1.3.1 $\Sigma C_{nd}(t)$ encoding and decoding for FlexO-n(e) + +The cumulative value of $C_{nd}(t)$ ( $\Sigma C_{nd}(t)$ ) is encoded in bits 4-8 of the FlexO justification control bytes JC4, JC5 and JC6. Bits D1 to D10 in JC4 and JC5 carry the value of $\Sigma C_{nd}(t)$ . Bit D1 carries the most significant bit and bit D10 carries the least significant bit. + +The CRC-3 is calculated over bits 6-8 in JC4 and JC5. The CRC-3 uses the $G(x) = x^3 + x^2 + 1$ generator polynomial, and is calculated as follows: + +- 1) The JC4 bits 6-8 and JC5 bits 6-8 are taken in network transmission order, most significant bit first, to form a 6-bit pattern representing the coefficients of a polynomial $M(x)$ of degree 5. +- 2) $M(x)$ is multiplied by $x^3$ and divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ of degree 2 or less. +- 3) The coefficients of $R(x)$ are considered to be a 3-bit sequence, where $x^2$ is the most significant bit. +- 4) This 3-bit sequence is the CRC-3 where the first bit of the CRC-3 to be transmitted is the coefficient of $x^2$ and the last bit transmitted is the coefficient of $x^0$ . + +The demapper process performs steps 1-3 in the same manner as the mapper process. In the absence of bit errors, the remainder shall be 000. + +NOTE – Refer to clause 6.2.8 of [b-ITU-T G.7044] for a parallel logic implementation of CRC-3. Replace RCOH1 and RCOH2 bits 1-3 by JC4 and JC5 bits 6-8. + +# Annex C + +## Transporting Ethernet client and Regen local degrade and remote degrade + +(This annex forms an integral part of this Recommendation.) + +## C.1 Ethernet client CSTAT LD/RD + +IP routers may support a "soft reroute" feature, which will direct IP traffic away from an optical link that experiences an increased number of forward error correction (FEC) errors on that optical link. 200G, 400G and 800G Gbit/s Ethernet interfaces that are compliant with [IEEE 802.3] will be able to support this feature. This application is described in more detail in Annex K of [ITU-T G.709]. + +[IEEE 802.3] has specified three bits in the alignment marker field (am\_sf<2:0>) to carry link status information to support this feature. Bit am\_sf<2> is defined as a remote degrade (RD) signal, bit am\_sf<1> is defined as a local degrade (LD) signal and bit am\_sf<0> is reserved. In the case of 800G Ethernet, the am\_sf<2:0> bits are duplicated and present in the two 400G PCS streams (flow 0 and flow 1) alignment marker fields. + +Note that in both Figures C.1 and C.2 router B includes the optional extender sublayer (XS) comprising a PHY XS connected to a DTE XS over an AUI. + +![Figure C.1: Local/remote degrade interworking between router and OTN muxponders/transponders for 200G/400G Ethernet. The diagram shows the flow of Ethernet client data and status signals (LD, RD, Reserved) through various layers (PCS, FEC, OTN, PHY XS) between Router A and Router B via OTN transponders X and Y. A legend at the bottom identifies green boxes as Ethernet FEC and blue boxes as OTN FEC.](0997dbaa9dfecedd60029d70b53327b8_img.jpg) + +The diagram illustrates the interworking of local and remote degrade signals between Router A and Router B through two OTN transponders, X and Y. The components and signal flows are as follows: + +- Router A:** Contains a PCS layer with Ethernet FEC blocks. It sends and receives alignment marker (am\_sf) bits: Reserved am\_sf<0>, RD am\_sf<2>, and LD am\_sf<1>. The LD am\_sf<1> signal is passed through an AND gate and then to the PCS layer of Router B. +- OTN transponder or muxponder X:** Consists of a (De)Mapper, OTN FEC blocks, and an OTN transponder application. It receives signals from Router A's PCS layer, processes them through the OTN transponder application, and passes them to the next stage. It also handles CSTAT signals: Reserved CSTAT[6], RD CSTAT[7], and LD CSTAT[8]. +- OTN transponder or muxponder Y:** Similar to transponder X, it contains a (De)Mapper, OTN FEC blocks, and an OTN transponder application. It receives signals from the previous stage and passes them to Router B. It also handles CSTAT signals: Reserved CSTAT[6], RD CSTAT[7], and LD CSTAT[8]. +- Router B:** Contains a PHY XS layer connected to a DTE XS layer over an AUI. It receives signals from the PCS layer of Router A (via the AND gate) and passes them through its own PCS layer to the PHY XS. It also receives and processes signals from the DTE XS layer, including the LD am\_sf<1> signal which is passed through an AND gate and then to the PCS layer of Router A. Router B also handles alignment marker (am\_sf) bits: Reserved am\_sf<0>, RD am\_sf<2>, and LD am\_sf<1>. + +The diagram also shows the flow of "Single optical span and FEC" between the two OTN transponders. A legend at the bottom indicates that green boxes represent Ethernet FEC and blue boxes represent OTN FEC. + +Figure C.1: Local/remote degrade interworking between router and OTN muxponders/transponders for 200G/400G Ethernet. The diagram shows the flow of Ethernet client data and status signals (LD, RD, Reserved) through various layers (PCS, FEC, OTN, PHY XS) between Router A and Router B via OTN transponders X and Y. A legend at the bottom identifies green boxes as Ethernet FEC and blue boxes as OTN FEC. + +G.709.1(24) + +Figure C.1 – Local/remote degrade interworking between router and OTN muxponders/transponders for 200G/400G Ethernet + +![Figure C.2: Local/remote degrade interworking between router and OTN muxponders/transponders for 800G Ethernet. The diagram shows the signal flow from Router A through OTN muxponder X, then through OTN muxponder Y, and finally to Router B. It details the handling of various alignment markers (am_sf<0>, am_sf<1>, am_sf<2>), RD and LD status bits, and the use of Ethernet and OTN FEC blocks. A legend at the bottom identifies green blocks as Ethernet FEC and blue blocks as OTN FEC.](cbab05075b3d7dc0d27c4cbb0c914a94_img.jpg) + +The diagram illustrates the interworking of 800G Ethernet signals between Router A and Router B via two OTN muxponders/transponders, X and Y. The signal is split into two flows (flow0 and flow1) at Router A, each passing through an Ethernet PCS and FEC block. The signals then enter OTN muxponder X, where they are processed through an OTN mapper and FEC blocks. The OTN transponder application and single optical span and FEC are shown in the center. The signals then pass through OTN muxponder Y, which performs similar processing. Finally, the signals are received by Router B through its own PCS and FEC blocks. The diagram shows the mapping of various alignment markers (am\_sf<0>, am\_sf<1>, am\_sf<2>), RD (Remote Defect) and LD (Link Defect) status bits, and the use of Ethernet and OTN FEC blocks. A legend at the bottom indicates that green blocks represent Ethernet FEC and blue blocks represent OTN FEC. + +Figure C.2: Local/remote degrade interworking between router and OTN muxponders/transponders for 800G Ethernet. The diagram shows the signal flow from Router A through OTN muxponder X, then through OTN muxponder Y, and finally to Router B. It details the handling of various alignment markers (am\_sf<0>, am\_sf<1>, am\_sf<2>), RD and LD status bits, and the use of Ethernet and OTN FEC blocks. A legend at the bottom identifies green blocks as Ethernet FEC and blue blocks as OTN FEC. + +G.709.1(24) + +**Figure C.2 – Local/remote degrade interworking between router and OTN muxponders/transponders for 800G Ethernet** + +The use case for 200GE and 400GE is illustrated in Figure C.1 and for 800GE in Figure C.2. The OTN muxponders/transponders X and Y can forward the information in the reserved ( $am\_sf<0>$ ) and RD ( $am\_sf<2>$ ) bits between ingress and egress muxponder/transponder. For 800G Ethernet client mapping illustrated in Figure C.2, the two sets of $am\_sf<2:0>$ values bits extracted from the two 400G PCS streams (flow 0 and flow 1) and present at the client interface shall be ORed to form a single set of $am\_sf<2:0>$ for further processing. The figures illustrate a single instance of client and CSTAT field, but muxponder designs may have multiple clients, whereas transponders would have a single client. The information in $am\_sf$ can be carried in CSTAT FlexO overhead using corresponding fields. The additional processing comprises the OR'ing of the LD status in the $am\_sf<1>$ bits of a 200GE, 400GE or 800GE signal with the local Ethernet pre-FEC BER link degrade status in the ingress transponder (X). In the egress transponder (Y), additional processing comprises the OR'ing of the LD status in CSTAT overhead bit of the FlexO signal with the local OTN pre-FEC BER link degrade status in the transponder (details defined by [ITU-T G.798]). The resulting LD status is then carried in the $am\_sf<1>$ bit of the 200GE, 400GE or 800GE signal. Note that in the case of 800 Gbit/s Ethernet signal, the single set of $am\_sf<2:0>$ bits value generated from the OTN demapping processes is duplicated towards both 400G flows (flow 0 and flow 1) at the client interface to be carried in both sets of alignment markers. + +## C.2 Ethernet client CSTAT and Regen RSTAT LD/RD + +The RSTAT field also contains LD/RD status bits and the use case is illustrated in Figure C.3. The OTN muxponder/transponder X is connected to a regen node. At a regen node, the received RSTAT[8] LD is ORed with the OTN pre-FEC BER link degrade status. + +In the opposite direction, muxponder/transponder X is terminating the FlexO section and demapping the Ethernet client; the received RSTAT[8] LD, as the received CSTAT[8] LD and OTN pre-FEC BER link degrade status are ORed to generate the Ethernet client's am\_sf<1> field as described in clause C.1. + +The RSTAT[7] RD field is only used for a single regen span. It is asserted in the reverse direction when a pre-FEC OTN link degrade is detected as shown in Figure C.3. + +Client Ethernet CSTAT LD/RD is fully transparent to the FlexO regen section. The CSTAT[7] RD signal and corresponding Ethernet client RD am\_sf<2> signal are not shown in Figure C.3 for clarity. + +![Figure C.3: Local/remote degrade interworking with regens. This block diagram shows the signal flow and status bit handling between Router A, an OTN muxponder/transponder X, and a Regen node. Router A contains PCS and Ethernet FEC blocks. The OTN muxponder/transponder X contains PCS, Ethernet FEC, OTN FEC, and a (De)Mapper. The Regen node contains a 'Regen section' and OTN FEC blocks. Status signals shown include RD CSTAT[7], RD RSTAT[7], LD CSTAT[8], and LD RSTAT[8]. LD am_sf<1> signals are generated at the Router A PCS and the OTN muxponder/transponder X (De)Mapper. Legend: Green box with 'FEC' is Ethernet FEC; Blue box with 'FEC' is OTN FEC.](1033dc9fde75540d224c907681b1b7aa_img.jpg) + +The diagram illustrates the interworking of local/remote degrade signals across different network elements. Router A's PCS block generates an LD am\_sf<1> signal (indicated by a '0' input to an OR gate) and receives an RD signal. This LD signal is passed to the OTN muxponder/transponder X. The OTN muxponder/transponder X contains a (De)Mapper that also generates an LD am\_sf<1> signal. The OTN transponder application within the muxponder transmits LD CSTAT[8], LD RSTAT[8], RD CSTAT[7], and RD RSTAT[7] signals. These signals are passed through the Regen section. At the Regen node, the LD RSTAT[8] signal is ORed with the OTN pre-FEC BER link degrade status. The regenerated signals (LD CSTAT[8], LD RSTAT[8], RD CSTAT[7], RD RSTAT[7]) are then passed back to the OTN muxponder/transponder X, which in turn passes them back to Router A. The legend indicates that green 'FEC' blocks represent Ethernet FEC and blue 'FEC' blocks represent OTN FEC. + +Figure C.3: Local/remote degrade interworking with regens. This block diagram shows the signal flow and status bit handling between Router A, an OTN muxponder/transponder X, and a Regen node. Router A contains PCS and Ethernet FEC blocks. The OTN muxponder/transponder X contains PCS, Ethernet FEC, OTN FEC, and a (De)Mapper. The Regen node contains a 'Regen section' and OTN FEC blocks. Status signals shown include RD CSTAT[7], RD RSTAT[7], LD CSTAT[8], and LD RSTAT[8]. LD am\_sf<1> signals are generated at the Router A PCS and the OTN muxponder/transponder X (De)Mapper. Legend: Green box with 'FEC' is Ethernet FEC; Blue box with 'FEC' is OTN FEC. + +G.709.1(24) + +Figure C.3 – Local/remote degrade interworking with regens + +# Appendix I + +## Example short-reach applications + +(This appendix does not form an integral part of this Recommendation.) + +FlexO-x-RS-m interface group can be used for a variety of applications. Example applications for a FlexO-x-RS interface are shown in Figure I.1 and Figure I.2. An interoperable interface might represent an OTN handoff between router (R) and transport (T) nodes, or could be a handoff between different administrative domains. + +![Figure I.1: Example FlexO-x-RS handoff router-transport. The diagram shows a router (R) connected to a transport (T) node, which is part of a transport/switch network. The router is connected to the transport node via a FlexO-x-RS-m interface. Below the network diagram, three horizontal lines represent the OTN layers: ODUk/flex (top), ODUCn (middle), and OTUCn (bottom). The ODUk/flex layer is continuous across the router and transport nodes. The ODUCn layer is shown as a dashed line between the router and transport nodes, indicating a handoff. The OTUCn layer is shown as a solid line between the router and transport nodes, indicating a handoff. The reference G.709.1-Y.1331.1(18)_FI.1 is at the bottom right.](03d9aaba6c1af8bfd8e42c1d2422ae5c_img.jpg) + +Figure I.1: Example FlexO-x-RS handoff router-transport. The diagram shows a router (R) connected to a transport (T) node, which is part of a transport/switch network. The router is connected to the transport node via a FlexO-x-RS-m interface. Below the network diagram, three horizontal lines represent the OTN layers: ODUk/flex (top), ODUCn (middle), and OTUCn (bottom). The ODUk/flex layer is continuous across the router and transport nodes. The ODUCn layer is shown as a dashed line between the router and transport nodes, indicating a handoff. The OTUCn layer is shown as a solid line between the router and transport nodes, indicating a handoff. The reference G.709.1-Y.1331.1(18)\_FI.1 is at the bottom right. + +**Figure I.1 – Example FlexO-x-RS handoff router-transport** + +The R-T topology is used in Figure I.1, to draw an analogy between FlexO-x-RS and FlexE use cases presented in [OIF FlexE]. The ODUk/flex (which can be a rate higher than 100Gbit/s) is the transport service (path) and maintenance entity in the OTN transport/switch network. The ODUCn/OTUCn is the section and FlexO-x-RS provides the interfacing capabilities (e.g., FEC, bonding and scrambling). + +![Figure I.2: Example FlexO-x-RS inter-domain handoff. The diagram shows two administrative domains, Admin domain A and Admin domain B, each containing a transport/switch network. In Admin domain A, there is an OTN XC and a regen node. In Admin domain B, there is an OTN XC node. The two domains are connected via a FlexO-x-RS-m interface. Below the network diagram, two horizontal lines represent the OTN layers: ODUk/flex (top) and ODUCn (bottom). The ODUk/flex layer is continuous across both domains. The ODUCn layer is shown as a dashed line between the regen node in Admin domain A and the OTN XC node in Admin domain B, indicating a handoff. The reference G.709.1(24) is at the bottom right.](b774dfc5023e15e9c352b97ca25a56d4_img.jpg) + +Figure I.2: Example FlexO-x-RS inter-domain handoff. The diagram shows two administrative domains, Admin domain A and Admin domain B, each containing a transport/switch network. In Admin domain A, there is an OTN XC and a regen node. In Admin domain B, there is an OTN XC node. The two domains are connected via a FlexO-x-RS-m interface. Below the network diagram, two horizontal lines represent the OTN layers: ODUk/flex (top) and ODUCn (bottom). The ODUk/flex layer is continuous across both domains. The ODUCn layer is shown as a dashed line between the regen node in Admin domain A and the OTN XC node in Admin domain B, indicating a handoff. The reference G.709.1(24) is at the bottom right. + +**Figure I.2 – Example FlexO-x-RS inter-domain handoff** + +The example of Figure I.2 shows a FlexO-x-RS inter-domain interface used as a handoff between two OTN switch/transport administrative domains (A and B). The administrative domains can represent different carriers, different equipment vendors within a carrier or different segments (metro vs core) within a carrier. + +# Appendix II + +## Example long-reach applications + +(This appendix does not form an integral part of this Recommendation.) + +FlexO-x(e)- ( = DO-modulation or DSH-modulation) group interfaces can be used for a variety of applications. + +Example applications for a FlexO-x(e)--m interface group are shown in Figure II.1 and Figure II.2. Such an interface group might represent an OTN handoff between router (R) and transport (T) nodes within one administrative domain or could be a handoff between OTN equipment of different vendors in one administrative domain. + +Optical transport networks are typically subdivided into metro and core where the core interconnects metro networks. Transport services may stay in one metro network or they may extend over different ones. In the latter case they may be passed through the core network. + +Network elements in the metro network play different roles such as metro/core gateway, edge towards customer and transit nodes. The customer facing functions lead to some diversity of client interfaces. Network elements from different vendors may be used to serve this broad scope of functions. FlexO long-reach interfaces could be used to interconnect network elements of different vendors or the same vendor. + +Figure II.1 illustrates an OTN core network with associated metro networks. The figure shows: + +- packet switching nodes (labelled Router) of vendor Z interconnected with the router of vendor X using a FlexO-x(e)--m interface group +- OTN ODU cross connect nodes with electrical switch fabric (labelled EXC) of vendor Z interconnected with EXC of either Z or vendor X using a FlexO-x--m interface group +- interconnection of the above EXC or router nodes through a metro OTN network which connects with a backbone/core network of the same vendor X, thereby allowing a single management domain +- interconnection of EXC or router nodes from the same vendor X, establishing a path over which the OCh or OTSiA overhead can be exchanged (via the OCC, internal to the network and not illustrated) as specified in [ITU-T G.872], [ITU-T G.709] and [b-ITU-T G.7712] enabling end-to-end optical path monitoring +- interconnection in backbone/core network is also possible if the FlexO-x(e)- FEC is adequate. + +Details of the optical paths supporting the FlexO-x(e)- signals are defined in [ITU-T G.698.2]. + +![Figure II.1: Example FlexO-x--m deployments in one administrative domain. The diagram shows four network scenarios: 1) Router vendor Z connected to Metro OTN network vendor Y via FlexO-x(e)--m over m fibres, which is then connected to Router vendor X. 2) EXC vendor Z connected to Metro OTN network vendor Y via FlexO-x(e)--m over m fibres, which is then connected to EXC. 3) EXC vendor Z connected to Metro OTN network vendor X via FlexO-x(e)--m over m fibres, which is then connected to EXC in a Backbone/core network Vendor X. 4) EXC connected to Metro OTN network vendor X via FlexO-x(e)--m over m fibres, which is then connected to EXC. A note indicates that FlexO-x(e)--m could potentially be used in the backbone/core networks if FEC is adequate. A legend defines EXC as Electrical OTN XC, OM/OD as Optical mux/demux, and OA as Optical amplifier.](7e14467740b2570a44379b347a697921_img.jpg) + +OTUCn or Ethernet + +FlexO-x(e)--m + +OCC + +Router vendor Z + +OM/OD OA + +OM/OD OA + +Router vendor X + +m fibres + +FlexO group + +Metro OTN network vendor Y + +OTUCn or Ethernet + +FlexO-x(e)--m + +OCC + +EXC vendor Z + +OM/OD OA + +OM/OD OA + +EXC + +m fibres + +FlexO group + +Metro OTN network vendor Y + +FlexO group + +OCC + +EXC vendor Z + +OM/OD OA + +OM/OD OA + +FlexO group + +EXC + +m fibres + +FlexO-x(e)--m + +OTUCn or Ethernet + +Metro OTN network vendor X + +Backbone/core network Vendor X + +FlexO-x(e)--m could potentially be used in the backbone/core networks if FEC is adequate + +EXC: Electrical OTN XC +OM/OD: Optical mux/demux +OA: Optical amplifier + +Metro OTN network vendor X + +FlexO group + +EXC + +OM/OD OA + +OM/OD OA + +FlexO group + +EXC + +m fibres + +FlexO-x(e)--m (can be hidden for management/control) + +OTUCn or Ethernet + +G.709.1(24) + +Figure II.1: Example FlexO-x--m deployments in one administrative domain. The diagram shows four network scenarios: 1) Router vendor Z connected to Metro OTN network vendor Y via FlexO-x(e)--m over m fibres, which is then connected to Router vendor X. 2) EXC vendor Z connected to Metro OTN network vendor Y via FlexO-x(e)--m over m fibres, which is then connected to EXC. 3) EXC vendor Z connected to Metro OTN network vendor X via FlexO-x(e)--m over m fibres, which is then connected to EXC in a Backbone/core network Vendor X. 4) EXC connected to Metro OTN network vendor X via FlexO-x(e)--m over m fibres, which is then connected to EXC. A note indicates that FlexO-x(e)--m could potentially be used in the backbone/core networks if FEC is adequate. A legend defines EXC as Electrical OTN XC, OM/OD as Optical mux/demux, and OA as Optical amplifier. + +**Figure II.1 – Example FlexO-x--m deployments in one administrative domain** + +Figure II.2 illustrates interconnection of the EXC or router nodes through a set of m point-to-point fibres, establishing an inter-domain group interface beyond the distances supported by the FlexO-x-RS-m specified in [ITU-T G.709.5] and [ITU-T G.959.1]. + +![Diagram showing two network deployment scenarios for FlexO-x(e)--m. The top scenario connects Router vendor Z to Router vendor X using m fibres, supporting OTUCn or Ethernet. The bottom scenario connects EXC vendor Z to EXC vendor X using m fibres. Both scenarios use FlexO-x(e)--m interfaces.](5a9cdc1fed33ae8fb871a8cd4d591729_img.jpg) + +OTUCn or Ethernet + +FlexO-x(e)--m + +Router vendor Z + +Router vendor X + +m fibres + +FlexO-x(e)--m + +EXC vendor Z + +EXC vendor X + +G.709.1(24) + +Diagram showing two network deployment scenarios for FlexO-x(e)--m. The top scenario connects Router vendor Z to Router vendor X using m fibres, supporting OTUCn or Ethernet. The bottom scenario connects EXC vendor Z to EXC vendor X using m fibres. Both scenarios use FlexO-x(e)--m interfaces. + +**Figure II.2 – Example FlexO-x(e)--m deployments establishing an inter-domain group interface beyond the distances supported by the FlexO-x-RS-m** + +# Bibliography + +- [b-ITU-T G.806] Recommendation ITU-T G.806 (2012), *Characteristics of transport equipment – Description methodology and generic functionality*. +- [b-ITU-T G.7044] Recommendation ITU-T G.7044/Y.1347 (2011), *Hitless adjustment of ODUflex(GFP)*. +- [b-ITU-T G.7712] Recommendation ITU-T G.7712/Y.1703 (2019), *Architecture and specification of data communication network*. +- [b-ITU-T G-Sup.58] ITU-T G-series Recommendations – Supplement 58 (2022), *Optical transport network module framer interfaces*. +- [b-ITU-T X.800] Recommendation ITU-T X.800 (1991), *Security architecture for Open Systems Interconnection for CCITT applications*. +- [b-IEEE 1588] IEEE 1588-2008 – *IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems*. +- [b-ISO/IEC 18033-3] ISO/IEC 18033-3:2010, *Information technology – Security techniques – Encryption algorithms – Part 3: Block ciphers*. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, 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Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.739** + +# **GENERAL ASPECTS OF DIGITAL TRANSMISSION SYSTEMS** + +## **TERMINAL EQUIPMENTS** --- + +## **CHARACTERISTICS OF AN EXTERNAL ACCESS EQUIPMENT OPERATING AT 2048 kbit/s OFFERING SYNCHRONOUS DIGITAL ACCESS AT 320 kbit/s AND/OR 64 kbit/s** + +**ITU-T Recommendation G.739** + +(Extract from the *Blue Book*) + +--- + +## NOTES + +1 ITU-T Recommendation G.739 was published in Fascicle III.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## **CHARACTERISTICS OF AN EXTERNAL ACCESS EQUIPMENT OPERATING AT 2048 kbit/s OFFERING SYNCHRONOUS DIGITAL ACCESS AT 320 kbit/s AND/OR 64 kbit/s** + +*(Melbourne, 1988)* + +This Recommendation gives the characteristics of equipment (external to PCM multiplexes) operating at 2048 kbit/s and providing one or several of the following tributaries into/from channel time slots of a 2048 kbit/s composite signal: + +- bidirectional synchronous 64 kbit/s access (Figure 1 a/G.739); +- unidirectional synchronous 320 kbit/s access (Figure 1 b/G.739). + +The 320 kbit/s channel is based on the allocation of 5 x 64 kbit/s time slots, e.g. for setting up sound-programme circuits according to Recommendations J.43 and J.44. Because these circuits are specified as unidirectional, the equipment for insertion/extraction has to be separated as shown in Figure 1 b/G.739. + +## **1 General characteristics** + +### **1.1 Bit rate** + +The nominal bit rate is 2048 kbit/s. The tolerance on this rate is $\pm 50$ parts per million (ppm). + +### **1.2 Types of external access** + +- a) Bidirectional synchronous insertion/extraction of 64 kbit/s data channels (see Figure 1 a/G.739). + +*Note 1* - The timing signal for the insertion side should be derived from the 2048 kbit/s incoming signal at the insertion side ( $I_0$ ); the timing signal for the extraction side should be derived from the 2048 kbit/s incoming signal at the extraction side ( $E_1$ ). + +*Note 2* - The provision of a timing signal output, available for the purpose of synchronizing other equipments, is an option that might be required depending upon national synchronization arrangements. + +*Note 3* - Further study is required on the possible need for an internal clock. + +- b) Unidirectional synchronous insertion and extraction of a digital sound-programme signal into/out of a 320 kbit/s channel (see Figure 1 b/G.739). + +*Note* - The synchronous insertion equipment for 320 kbit/s signals requires the internal regeneration of a timing signal synchronized by the 2048 kbit/s input signal $I_0$ . This timing signal output of the synchronous insertion equipment is used for synchronizing the sampling frequency of the analogue/digital converter. + +## **2 Frame structure and use of derived channel time slots** + +### **2.1 Frame structure of the 2048 kbit/s signal** + +Refer to § 2.3 of Recommendation G.704. Bit 1 of the frame should be used in accordance with § 2.3.3 of Recommendation G.704, i.e. for a CRC check bit procedure. + +### **2.2 Use of derived channel time slots** + +Time slots not accessed flow transparently through the equipment. + +*Note* - Further study is required as to whether the binary content of time slots used at the access points should be replaced, after extraction from the composite signal, by the AIS. + +#### 2.2.1 64 kbit/s access + +The number of accessible channel time slots should be at least four and the equipment shall allow access to any of channel time slots 1 to 15 and 17 to 31. + +*Note* - Equipment exists which provides access to at least four channel time slots in the following order of priority: 6 - 22 - 14 - 30 - 2 - 18 - 10 - 26 - 4 - 20 - 12 - 28 - 8 - 24 - 5 - 21 - 13 - 29 - 1 - 17 - 9 - 25 - 3 - 19 - 11 - 27 - 7 - 23 - 15 - 31. + +![Diagram (a) showing bidirectional synchronous insertion/extraction of 64 kbit/s data channels. A central rectangular block represents the equipment. On the left, a '2048 kbit/s interface' has input I0 and output E0. On the right, another '2048 kbit/s interface' has output I1 and input E1. Below the central block, a '64 kbit/s interface' shows multiple pairs of inputs (I2) and outputs (E2) connected to the equipment via dashed lines representing channel paths.](d3ca266c298aeb34b019960c6c36f187_img.jpg) + +Diagram (a) showing bidirectional synchronous insertion/extraction of 64 kbit/s data channels. A central rectangular block represents the equipment. On the left, a '2048 kbit/s interface' has input I0 and output E0. On the right, another '2048 kbit/s interface' has output I1 and input E1. Below the central block, a '64 kbit/s interface' shows multiple pairs of inputs (I2) and outputs (E2) connected to the equipment via dashed lines representing channel paths. + +*a) Bidirectional synchronous insertion/extraction of 64 kbit/s data channels* + +![Diagram (b) showing unidirectional synchronous insertion and extraction of digital sound-programme (DSP) signal. The top part shows a '2048 kbit/s interface' on the left with I0 and E0, and on the right with I1 and E1. A central block has 'DSP access' points I3 and T (Timing signal) on top, and E3 on the bottom. The bottom part shows another '2048 kbit/s interface' with I0, E0, I1, and E1, and a central block with 'DSP access' points E3 on the bottom.](f0bae10b54c4f3cf8d0e33f5e2fb7cfa_img.jpg) + +Diagram (b) showing unidirectional synchronous insertion and extraction of digital sound-programme (DSP) signal. The top part shows a '2048 kbit/s interface' on the left with I0 and E0, and on the right with I1 and E1. A central block has 'DSP access' points I3 and T (Timing signal) on top, and E3 on the bottom. The bottom part shows another '2048 kbit/s interface' with I0, E0, I1, and E1, and a central block with 'DSP access' points E3 on the bottom. + +*b) Unidirectional synchronous insertion and extraction of digital sound-programme (DSP) signal into/out of a 320 kbit/s channel* + +| | | +|--------------------------------|--------------------------------------------------------------| +| $I_0, I_1$ Insertion side | $I_3, E_3$ Synchronous digital sound-programme signal access | +| $E_0, E_1$ Extraction side | T Timing signal | +| $I_2, E_2$ 64 kbit/s interface | | + +FIGURE 1/G.739 + +**External access equipment for 64 and 320 kbit/s channels** + +#### 2.2.2 320 kbit/s access + +The time slot allocation for digital channels with bit rate at 320 kbit/s is given in Table 1/G.739. + +TABLE 1/G.739 + +| 320 kbit/s channels (Note 1) | | | | | | Digital sound-programme access points | +|------------------------------|--------------------------|------------------------------|------------------------------|------------------------------|------------------------------|---------------------------------------| +| A | B | C | D | E | F | | +| 1 - 2 -
3 - 4 -
5 | 6 - 7 -
8 - 9 -
10 | 11 - 12
- 13 -
14 - 15 | 17 - 18
- 19 -
20 - 21 | 22 - 23
- 24 -
25 - 26 | 27 - 28
- 29 -
30 - 31 | I3, T, E3
Figure 1b/G.738 | + +Note 1 - The six possible 320 kbit/s channels in a 2048 kbit/s stream are numbered A to F. Preferably the channel pairs A-B, C-D and E-F should be used for stereophonic transmission. + +Note 2 - If the channel time slot 16 which is assigned to signalling as covered in § 5 is not needed for signalling, it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. + +## 3 Frame alignment and CRC procedures both at insertion (I0) and extraction (E1) sides + +An illustration of the procedure is given in Figure 2/G.706. + +### 3.1 Loss of frame alignment + +Refer to § 4.1.1 of Recommendation G.706. + +### 3.2 Recovery of frame alignment + +Refer to § 4.1.2 of Recommendation G.706. + +### 3.3 CRC multiframe alignment in TSO + +Refer to § 4.2 of Recommendation G.706. + +### 3.4 CRC bit monitoring + +Refer to § 4.3 of Recommendation G.706. + +## 4 Fault conditions and consequent actions + +### 4.1 Fault conditions + +The equipment should detect the following conditions: + +#### 4.1.1 Failure of power supply. + +#### 4.1.2 Loss of incoming signal at I2 or I3. + +Note - This detection is not mandatory when contradirectional interfaces are used. + +4.1.3 Loss of the incoming signal at 2048 kbit/s both at insertion ( $I_0$ ) and extraction ( $E_1$ ) sides. + +*Note 1* - The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. + +*Note 2* - Where separate circuits are used for the digital signal and the timing signal, the loss of either or both should constitute loss of the incoming signal. + +4.1.4 Loss of frame alignment both at insertion ( $I_0$ ) and extraction ( $E_1$ ) sides. + +4.1.5 Excessive bit error ratio detected by monitoring the frame alignment signal at both the insertion ( $I_0$ ) and extraction ( $E_1$ ) sides. + +*Note* - The detection of this fault condition at insertion side ( $I_0$ ) depends on the type of application of this equipment in a network and therefore is not mandatory. + +4.1.5.1 With a random bit error ratio of $\leq 10^{-4}$ , the probability of activating the indication of fault condition within a few seconds should be less than $10^{-6}$ . + +With a random bit error ratio of $\geq 10^{-3}$ , the probability of activating the indication of fault condition within a few seconds should be higher than 0.95. + +4.1.5.2 With a random bit error ratio of $\geq 10^{-3}$ , the probability of deactivating the indication of fault condition within a few seconds should be almost 0. + +With a random bit error ratio of $\leq 10^{-4}$ , the probability of deactivating the indication of fault condition within a few seconds should be higher than 0.95. + +*Note* - The activating and deactivating period specified as "a few seconds" is intended to be in the order of 4 to 5 seconds. + +### 4.2 *Consequent actions* + +Further to the detection of fault condition, appropriate actions should be taken as specified in Table 2/G.739. The consequent actions are as follows: + +4.2.1 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. When the AIS at the 2048 kbit/s inputs ( $I_0$ , $E_1$ ) is detected (see General Notes below to § 4.2), the prompt maintenance alarm indication associated with loss of frame alignment (see § 4.1.4) and excessive error rate (see § 4.1.5) should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table 2/G.739 with the two fault conditions. + +*Note* - The location and provision of any visual and/or audible alarm activated by the alarm indications given in § 4.2.1 is left to the discretion of each Administration. + +4.2.2 AIS applied to $E_2$ , $E_3$ outputs (see General Notes below to § 4.2). This action should be taken as soon as possible and not later than 2 ms after the detection of the fault condition. + +4.2.3 AIS applied to relevant time slots in the composite 2048 kbit/s output signal at insertion side ( $I_1$ ) if supervision of the incoming $I_2$ and $I_3$ signal is provided. + +4.2.4 Inhibition of $I_2$ or $I_3$ digital information insertion. + +4.2.5 Both 2048 kbit/s signals are bypassed. + +*Note* - The provision of this consequent action depends on the type of application of this equipment in a network and therefore is not mandatory. + +4.2.6 AIS applied to the 2048 kbit/s output, extraction side ( $E_0$ ). + +*Note* - The provision of this consequent action depends on the type of application of this equipment in a network and therefore is not mandatory. + +4.2.7 AIS applied to the 2048 kbit/s output, insertion side ( $I_1$ ). + +*Note* - The provision of this consequent action depends on the type of this equipment in a network and therefore is not mandatory. + +*General Notes to § 4.2* + +*Note 1* - The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of binary 1s. The strategy for detecting the presence of the AIS should be such that with a high probability the AIS is detectable even in the presence of random errors having a mean error ratio $1 \times 10^{-3}$ . Nevertheless, a signal in which all the binary elements, with the exception of the frame alignment signal, are in the state 1, should not be taken as an AIS. + +*Note 2* - All timing requirements quoted apply equally to restoration, subsequent to the fault condition clearing. + +## 5 Interfaces + +The digital interfaces at 2048 kbit/s should be in accordance with Recommendation G.703. + +The digital interfaces at 64 kbit/s should be either of the codirectional or the contradirectional type specified in Recommendation G.703. + +The need to define a digital interface operating at 320 kbit/s is under study. + +*Note 1* - It should be noted that according to the principle of minimizing the number of different types of interfaces, the information rate of 320 kbit/s will be offered to customers at the user/network interface level using the 2048 kbit/s interface as defined in Recommendations I.431 and G.703. + +*Note 2* - In the case of the 64 kbit/s codirectional interface, the design of the input ports should take into account the need to provide octet alignment, to allow controlled slips when the tributary timing and that of the multiplexer timing source are plesiochronous, and to absorb jitter and wander up to the limits given in Recommendation G.823. + +**TABLE 2/G.739** +**Fault conditions and consequent actions for the external access equipment** + +| Fault conditions (see § 4.1) | | Consequent actions (see § 4.2) | | | | Both 2048 kbit/s signals are bypassed (see Note under § 4.2.5) | AIS applied to the 2048 kbit/s output, extraction side (E 0 ) (see Note under § 4.2.6) | AIS applied to the 2048 kbit/s output, insertion side (I 1 ) (see Note under § 4.2.7) | +|---------------------------------------------------------------------------------------------|---------------------------|------------------------------------------------|---------------------------------------------------------|-----------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------|---------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------| +| | | Prompt maintenance alarms indication generated | AIS applied to E 2 or E 3 outputs | Inhibition of digital information insertion I 2 , I 3 | AIS applied to the relevant time slot of the 2048 kbit/s composite signal at insertion side (I 0 ) | | | | +| Failure of power supply | | Yes | | | | Yes | Yes
(if practicable) | Yes
(if practicable) | +| Loss of incoming signal at I 2 or I 3 inputs (see Note under § 4.1.2) | | Yes | | | Yes | | | | +| Loss of incoming signal at 2048 kbit/s | Extr.s. (E 1 ) | Yes | Yes | | | | Yes | | +| | Ins.s. (I 0 ) | Yes | | Yes | | | | Yes | +| Loss of frame alignment (see Note 2 of Rec. G.706, § 4.2) | Extr.s. (E 1 ) | Yes
(see § 4.2.1) | Yes | | | | Yes | | +| | Ins.s. (I 0 ) | Yes
(see § 4.2.1) | | Yes | | | | Yes | +| Error ratio $1 \cdot 10^{-3}$ on the frame | Extr.s. (E 1 ) | Yes
(see § 4.2.1) | Yes | | | | Yes | | +| alignment signal (see Note under § 4.1.5) | Ins.s. (I 0 ) | Yes
(see § 4.2.1) | | Yes | | | | Yes | + +*Note* - A *Yes* in the table signifies that an action should be taken as a consequence of the relevant fault condition. An *open space* in the table signifies that the relevant action should not be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present, the relevant action should be taken if, for at least one of the conditions, a *Yes* is defined in relation to this action. + +## 6 Jitter + +### 6.1 Jitter at 2048 kbit/s output + +When there is no jitter on the 2048 kbit/s inputs ( $I_0$ , $E_1$ ) the peak-to-peak jitter at the 2048 kbit/s outputs ( $I_1$ , $E_0$ ) should not exceed 0.10 UI when it is measured within the frequency range from $f_1 = 20$ Hz to $f_4 = 100$ kHz. The equivalent binary content of the test signal applied at the 2048 kbit/s input shall be a pseudo-random bit sequence of length $2^{15} - 1$ as specified in Recommendation O.151. See Figure 2/G.823. + +*Note* - It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. + +### 6.2 Jitter at $E_2$ and $E_3$ outputs + +6.2.1 The jitter at the $E_2$ (64 kbit/s) output when there is no jitter at the 2048 kbit/s input ( $E_1$ ) should not exceed 0.025 UI when measured within the frequency range from $f_1 = 20$ Hz to $f_4 = 100$ kHz. The equivalent binary content of the test signal applied at the 2048 kbit/s input shall be a pseudo-random bit sequence of length $2^{15} - 1$ as specified in Recommendation O.151. + +*Note* - In order to carry out this measurement without invoking AIS at the 64 kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. + +6.2.2 Since the physical and electrical characteristics of a 320 kbit/s interface are identical to those of the 2048 kbit/s interface, the jitter at the $E_3$ (synchronous 320 kbit/s) output when there is no jitter at the 2048 kbit/s input ( $E_1$ ) is according to § 6.1 above. + +### 6.3 Jitter transfer functions + +6.3.1 The jitter transfer function between the 2048 kbit/s input ( $I_0$ , $E_1$ ) and the output ( $I_1$ , $E_0$ ) should not exceed the gain/frequency limits given in Figure 2/G.739. + +Some Administrations require that equipment be fitted with jitter reducers. In this case, the jitter transfer function should not exceed the gain/frequency limits given in Figure 3/G.739. + +*Note 1* - The 2048 kbit/s signal shall be modulated with sinusoidal jitter. The equivalent binary content of the test signal shall be 1000. + +*Note 2* - It may be necessary to include a frame alignment signal in the test signal to enable the measurement to be carried out. + +6.3.2 The jitter transfer function between the 2048 kbit/s input ( $E_1$ ) and the $E_2$ (64 kbit/s) output should not exceed -29.6 dB when measured over the frequency range $f_0$ to 10 kHz. The frequency $f_0$ should be less than 20 Hz and as low as possible (e.g. 10 Hz), taking into account the limitations of measuring equipment. + +*Note 1* - The 2048 kbit/s test signal shall be modulated by sinusoidal jitter. The equivalent binary content of the test signal shall be 1000. + +*Note 2* - In order to carry out this measurement without invoking AIS at the 64 kbit/s output, it will normally be necessary to include a frame alignment signal in the test signal. + +*Note 3* - The jitter reduction of 1/32 due to demultiplexing is equivalent to -30.1 dB. + +6.3.3 Since the physical and electrical characteristics of a 320 kbit/s interface are identical to those of the 2048 kbit/s interface, the jitter transfer function between the 2048 kbit/s input ( $E_1$ ) and $E_3$ (synchronous 320 kbit/s) output is according to § 6.3.1 above. + +![Figure 2/G.739: A graph showing the relationship between 20 log J_out/J_in (dB) and frequency. The y-axis ranges from -19.5 to 0.5 dB. The x-axis has markers for f_0, 1.4 kHz, 36 kHz, and 100 kHz. The graph shows a flat region at 0.5 dB from f_0 to 1.4 kHz, a downward slope of 20 dB/decade from 1.4 kHz to 36 kHz, and a flat region at -8.4 dB from 36 kHz to 100 kHz. A shaded region is shown above the 0.5 dB line and below the -8.4 dB line. A dashed horizontal line is drawn at approximately 0.1 dB. A label 'Note 3' with an arrow points to the downward slope. The code 'TI502350-89' is at the bottom right.](adb1f42239329fa8283d1a40005f989f_img.jpg) + +Figure 2/G.739: A graph showing the relationship between 20 log J\_out/J\_in (dB) and frequency. The y-axis ranges from -19.5 to 0.5 dB. The x-axis has markers for f\_0, 1.4 kHz, 36 kHz, and 100 kHz. The graph shows a flat region at 0.5 dB from f\_0 to 1.4 kHz, a downward slope of 20 dB/decade from 1.4 kHz to 36 kHz, and a flat region at -8.4 dB from 36 kHz to 100 kHz. A shaded region is shown above the 0.5 dB line and below the -8.4 dB line. A dashed horizontal line is drawn at approximately 0.1 dB. A label 'Note 3' with an arrow points to the downward slope. The code 'TI502350-89' is at the bottom right. + +*Note 1* - The frequency $f_0$ should be less than 20 Hz and as low as possible (e.g. 10 Hz), taking into account the limitations of measuring equipment. + +*Note 2* - To achieve accurate measurements, the use of a selective method is recommended with a bandwidth sufficiently small referred to the relevant measurement frequency, but not wider than 40 Hz. + +*Note 3* - For interfaces within national boundaries, this characteristic may be used. + +FIGURE 2/G.739 + +![Figure 3/G.739: A graph showing the relationship between 20 log J_out/J_in (dB) and frequency. The y-axis ranges from -19.5 to 0.5 dB. The x-axis has markers for f_0, 40 Hz, 400 Hz, and 100 kHz. The graph shows a flat region at 0.5 dB from f_0 to 40 Hz, a downward slope of 20 dB/decade from 40 Hz to 400 Hz, and a flat region at -19.5 dB from 400 Hz to 100 kHz. A shaded region is shown above the 0.5 dB line and below the -19.5 dB line. A dashed horizontal line is drawn at approximately 0.1 dB. The code 'TI502360-89' is at the bottom right.](8ee3b76dd49f31624d287885bc2c81ee_img.jpg) + +Figure 3/G.739: A graph showing the relationship between 20 log J\_out/J\_in (dB) and frequency. The y-axis ranges from -19.5 to 0.5 dB. The x-axis has markers for f\_0, 40 Hz, 400 Hz, and 100 kHz. The graph shows a flat region at 0.5 dB from f\_0 to 40 Hz, a downward slope of 20 dB/decade from 40 Hz to 400 Hz, and a flat region at -19.5 dB from 400 Hz to 100 kHz. A shaded region is shown above the 0.5 dB line and below the -19.5 dB line. A dashed horizontal line is drawn at approximately 0.1 dB. The code 'TI502360-89' is at the bottom right. + +*Note 1* - The frequency $f_0$ should be less than 20 Hz and as low as possible (e.g. 10 Hz), taking into account the limitations of measuring equipment. + +*Note 2* - To achieve accurate measurements, the use of a selective method is recommended with a bandwidth sufficiently small referred to the relevant measurement frequency, but not wider than 40 Hz. + +FIGURE 3/G.739 \ No newline at end of file diff --git a/marked/G/T-REC-G.747-198811-I_PDF-E/0ad3f61f997eb05afb341fc46024bf2b_img.jpg b/marked/G/T-REC-G.747-198811-I_PDF-E/0ad3f61f997eb05afb341fc46024bf2b_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..ad9402f5874c9f439fb4f06355201f9b21f80a1e --- /dev/null +++ b/marked/G/T-REC-G.747-198811-I_PDF-E/0ad3f61f997eb05afb341fc46024bf2b_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:971525e1f7a76f96d052893c274a87bad1a0010d0e76c4bd4be74bc0cee8d90a +size 46942 diff --git a/marked/G/T-REC-G.747-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.747-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..64672153e39c851d9e16fdbc702e526c7ba7e8a7 --- /dev/null +++ b/marked/G/T-REC-G.747-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:454a9958ffe168868cb7d38a0eb24418dafe31a7a4245c992089b2316ac37d3e +size 7392 diff --git a/marked/G/T-REC-G.747-198811-I_PDF-E/7a3561af571faf036baa93f5f4b1bdb9_img.jpg b/marked/G/T-REC-G.747-198811-I_PDF-E/7a3561af571faf036baa93f5f4b1bdb9_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..0b42ef5f3481111fb8441838e12e01b3dca7fc6c --- /dev/null +++ b/marked/G/T-REC-G.747-198811-I_PDF-E/7a3561af571faf036baa93f5f4b1bdb9_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:3cfa8f6b5478a5e29ecabe9ee4fcdddcaccac5f4c6772563284fdffd71b5acf6 +size 23110 diff --git a/marked/G/T-REC-G.747-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.747-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..7046d6f45a7bbb646acda790cf2de62f7e9821a2 --- /dev/null +++ b/marked/G/T-REC-G.747-198811-I_PDF-E/raw.md @@ -0,0 +1,233 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' written across the center. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.747** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**GENERAL ASPECTS OF DIGITAL TRANSMISSION +SYSTEMS** + +**TERMINAL EQUIPMENTS** + +--- + +**SECOND ORDER DIGITAL MULTIPLEX +EQUIPMENT OPERATING AT 6312 kbit/s +AND MULTIPLEXING THREE TRIBUTARIES +AT 2048 kbit/s** + +**ITU-T Recommendation G.747** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.747 was published in Fascicle III.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **SECOND ORDER DIGITAL MULTIPLEX EQUIPMENT OPERATING AT 6312 kbit/s AND MULTIPLEXING THREE TRIBUTARIES AT 2048 kbit/s** + +*(Melbourne, 1988)* + +## **1 General** + +The digital multiplex equipment described in this Recommendation is intended for use between networks using different digital hierarchies as specified in Recommendations G.702 and G.802. + +## **2 Bit rate** + +The bit rates of the tributary and multiplex signals should be $2048 \text{ kbit/s} \pm 50 \text{ ppm}$ and $6312 \text{ kbit/s} \pm 30 \text{ ppm}$ , respectively, as specified in Recommendation G.703. + +## **3 Frame structure** + +Table 1/G.747 gives the recommended 6312 kbit/s multiplexing frame structure. + +## **4 Loss and recovery of frame alignment and consequent action** + +Loss of frame alignment should be assumed to have taken place when four consecutive frame alignment signals have been incorrectly received in their predicted positions. + +When frame alignment is assumed to be lost, the frame alignment device should decide that such alignment has effectively been recovered when it detects the presence of three consecutive correct frame alignment signals. + +The frame alignment device, having detected the appearance of a single correct frame alignment signal, should begin a new search for the frame alignment signal when it detects the absence of the frame alignment signal in one of the two following frames. + +*Note* - As it is not strictly necessary to specify the detailed frame alignment strategy, any suitable frame alignment strategy may be used provided the performance achieved is at least as efficient in all respects as that obtained by the above frame alignment strategy. + +## **5 Multiplexing and justification methods** + +Cyclic bit interleaving in the tributary numbering order and positive justification are recommended. + +The justification control signal should be distributed and use the $C_{ji}$ -bits ( $j = 1, 2, 3; i = 1, 2, 3$ ) (see Note 5 to Table 1/G.747). + +Positive justification should be indicated by the justification control signal 111 and no justification by the signal 000. Majority decision is recommended. + +Table 1/G.747 gives the maximum justification rate per tributary and the nominal justification ratio. + +TABLE 1/G.747 +**6312 kbit/s multiplexing frame structure** + +| | | +|------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------| +| Nominal tributary bit rate (kbit/s) | 2048 | +| Number of tributaries | 3 | +| Frame structure | Bit number | +| Frame alignment signal (111010000)
Bits from tributaries | Set I
1 to 9
10 to 168 | +| Alarm indication to the remote multiplex equipment (Note 1)
Parity bit (Notes 2 and 3)
Bit reserved for future use (Note 4)
Bits from tributaries | Set II
1
2
3
4 to 168 | +| Justification control bits $C_{j1}$ (Note 5)
Bits from tributaries | Set III
1 to 3
4 to 168 | +| Justification control bits $C_{j2}$ (Note 5)
Bits from tributaries | Set IV
1 to 3
4 to 168 | +| Justification control bits $C_{j3}$ (Note 5)
Bits from tributaries available for justification
Bits from tributaries | Set V
1 to 3
4 to 6
7 to 168 | +| Frame length | 840 bits | +| Bits per tributary in a frame | 273 bits | +| Maximum justification rate per tributary | 7.5 kbit/s | +| Nominal justification ratio | 0.453 | + +*Note 1* - See § 10.2.1. + +*Note 2* - The parity bit = 1 if the number of marks in all tributary bits including the bits in the justifiable time-slots in the preceding frame is odd; the parity bit = 0 if the number of marks in all tributary bits including the bits in the justifiable time-slots in the preceding frame is even. + +*Note 3* - The implementation and the use of this parity bit procedure are for further study. + +*Note 4* - This bit should be set to 1 when not used. + +*Note 5* - $C_{ji}$ ( $j = 1, 2, 3$ ; $i = 1, 2, 3$ ) indicates the $i$ th justification control bit of the $j$ th tributary. + +## 6 jitter + +### 6.1 *Mulder jitter transfer characteristic* + +A 2048 kbit/s signal, modulated by sinusoidal jitter, should be subject to a muldex jitter transfer characteristic + +within the gain/frequency limits given in Figure 1/G.747. The equivalent binary content of the test signal should be 1000. + +*Note* - In addition, the need to specify a demultiplexer tributary jitter transfer characteristic from the 6312 kbit/s demultiplexer input to the 2048 kbit/s demultiplexer output is for further study. + +![Figure 1/G.747: Muldex jitter transfer characteristic. The graph shows Jitter gain (dB) on the y-axis (0 to 0.5) versus Frequency (f) (log scale) in Hz on the x-axis. The gain is 0.5 dB from f0 to fc = 40 Hz, then decreases with a 20 dB/decade slope to 0 dB at 400 Hz. The region above 0.5 dB is shaded. The label 'CCITT - 31720' is at the bottom right.](7a3561af571faf036baa93f5f4b1bdb9_img.jpg) + +Figure 1/G.747: Muldex jitter transfer characteristic. The graph shows Jitter gain (dB) on the y-axis (0 to 0.5) versus Frequency (f) (log scale) in Hz on the x-axis. The gain is 0.5 dB from f0 to fc = 40 Hz, then decreases with a 20 dB/decade slope to 0 dB at 400 Hz. The region above 0.5 dB is shaded. The label 'CCITT - 31720' is at the bottom right. + +*Note* - The frequency $f_0$ should be as low as possible, taking into account the limitations of measuring equipment. In any case, $f_0$ should be no greater than 10 Hz. The selective measurement method should be used. + +FIGURE 1/G.747 + +#### **Muldex jitter transfer characteristic** + +### 6.2 *Output jitter* + +#### 6.2.1 *Tributary output jitter* + +With no jitter applied to the input ports of the multiplexer and with the multiplexer directly connected to the demultiplexer, the peak-to-peak jitter at the tributary output port should not exceed 0.2 UI over a measurement interval of one minute in the frequency range from $f_0$ to 100 kHz (see Note 1). + +When measured with an instrument incorporating a bandpass filter having a lower cutoff frequency of 18 kHz, a roll-off of 20 dB/decade and an upper limit of 100 kHz, the peak-to-peak output jitter should not exceed 0.05 UI when measured over a one minute interval (see Note 2). + +*Note 1* - The frequency $f_0$ should be as low as possible, taking into account the limitations of measurement equipment. In any case $f_0$ should be no greater than 10 Hz. + +*Note 2* - For interfaces meeting the national high Q option, detailed in Recommendation G.823, the lower cutoff frequency for the above measurement should be 700 Hz. + +#### 6.2.2 *Multiplexer output jitter* + +The peak-to-peak jitter at the 6312 kbit/s output port should not exceed 0.05 UI when it is measured over one minute interval within the frequency range from $f_1 = 10$ Hz to $f_4 = 60$ kHz. + +### 6.3 *Input jitter* + +#### 6.3.1 *Tributary input jitter* + +The 2048 kbit/s input port should be capable of accommodating levels of input jitter up to the limits given in + +#### 6.3.2 *Demultiplexer input jitter* + +The 6312 kbit/s input port should be capable of accommodating levels of input jitter up to the limits given in Figure 2/G.747. + +*Note 1* - Current Recommendation G.703 does not refer to the jitter tolerated at the digital distribution frame at 6312 kbit/s nor at the input port of equipment connected to this distribution frame. + +*Note 2* - The jitter accommodation requirement should be met when the jittered input signal is composed of the multiplexed tributary signals having any value of jitter allowed for the 2048 kbit/s. + +![A log-log plot showing peak-to-peak sinusoidal jitter amplitude versus jitter frequency. The y-axis is labeled 'Peak-to-peak sinusoidal jitter amplitude (log scale)' with values A1 and A2. The x-axis is labeled 'Jitter frequency (log scale)' with values f1, f2, f3, and f4. The plot shows a horizontal line at A1 from f1 to f2, a downward sloping line from f2 to f3 with a label '20 dB/decade', and a horizontal line at A2 from f3 to f4. The label 'TI502370-89' is in the bottom right corner.](0ad3f61f997eb05afb341fc46024bf2b_img.jpg) + +| Peak-to-peak sinusoidal jitter amplitude | | Frequency | | | | +|------------------------------------------|---------------------|---------------------|---------------------|----------------------|----------------------| +| A 1 (UI) | A 2 (UI) | f 1 (Hz) | f 2 (Hz) | f 3 (kHz) | f 4 (kHz) | +| 5.0 | 0.15 | 10 | 120 | 4 | 60 | + +A log-log plot showing peak-to-peak sinusoidal jitter amplitude versus jitter frequency. The y-axis is labeled 'Peak-to-peak sinusoidal jitter amplitude (log scale)' with values A1 and A2. The x-axis is labeled 'Jitter frequency (log scale)' with values f1, f2, f3, and f4. The plot shows a horizontal line at A1 from f1 to f2, a downward sloping line from f2 to f3 with a label '20 dB/decade', and a horizontal line at A2 from f3 to f4. The label 'TI502370-89' is in the bottom right corner. + +FIGURE 2/G.747 + +##### **Lower limit of maximum tolerable sinusoidal input jitter at 6312 kbit/s** + +## **7 Digital interfaces** + +The digital interfaces at 2048 kbit/s and 6312 kbit/s should be in accordance with Recommendation G.703. + +## **8 Timing signal** + +If it is economically feasible, it may be desirable to be able to derive the multiplexing timing signal from an external source as well as from an internal source. + +## 9 Service digits + +Three bits per frame are available for service functions (see Table 1/G.747): bit 1 of Set II is used to transmit an alarm indication to the remote multiplex equipment when specific fault conditions are detected in the multiplex equipment (see § 10 below); bit 2 of Set II may be used for a parity check; bit 3 of Set II is reserved for future use. + +## 10 Fault conditions and consequent actions + +### 10.1 Fault conditions + +10.1.1 The digital multiplex equipment should detect the following fault conditions: + +- 1) failure of power supply; +- 2) loss of an incoming 2048 kbit/s tributary signal at a multiplexer input port; +- 3) loss of an incoming 6312 kbit/s multiplex signal at a demultiplexer input port; +- 4) loss of frame alignment signal at a demultiplexer input port; +- 5) detection of an alarm indication received from the remote multiplex equipment at a demultiplexer input port; +- 6) detection of alarm indication signal (AIS) at a demultiplexer input port. + +*Note 1* – The equivalent binary content of the AIS at 2048 and 6312 kbit/s should be a continuous stream of binary 1s (marks) as recommended in Recommendation M.20. + +*Note 2* – Some current 44 736/6312 kbit/s demultiplexers do not issue a 6312 kbit/s AIS. Thus no detection can take place in that case. + +*Note 3* – The strategy for detecting the presence of the AIS should be such that the AIS is detectable even in the presence of an error ratio of $1 \cdot 10^{-3}$ . However, a signal with all bits except the frame alignment signal in the state of 1 should not be mistaken as an AIS. + +10.1.2 The need to monitor the degradation of the incoming 6312 kbit/s signal for the purpose of end-to-end error performance monitoring of the 6132 kbit/s digital block as well as the procedure for detecting such degradation, are for further study. + +### 10.2 Consequent actions + +Further to the detection of a fault condition, the appropriate actions should be taken as specified in Table 2/G.747. + +*Note 1* – The concept and definition of prompt maintenance alarm indication is given in Recommendation M.20. + +*Note 2* – When the alarm indication signal (AIS) is detected at the input of the demultiplexer, the prompt maintenance alarm indication associated with loss of frame alignment should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table 2/G.747 with the fault condition. + +10.2.1 Alarm indication to the remote multiplex equipment should be generated by changing bit 1 of Set II (see Table 1/G.747) from the state 0 to the state 1. + +10.2.2 AIS should be applied to the following as specified in Table 2/G.747. + +- all three 2048 kbit/s tributary outputs from the demultiplexer; +- 6312 kbit/s output of the multiplexer; +- the time slots of the 6312 kbit/s signal at the output of the multiplexer, corresponding to the relevant 2048 kbit/s tributary. + +TABLE 2/G.747 + +### **Fault conditions and consequent actions** + +| Equipment part | Fault condition (see § 10.1) | Consequent actions (see § 10.2) | | | | | +|-------------------------------|---------------------------------------------------------------|-----------------------------------------------|--------------------------------------------------------------|------------------------|-------------------------|----------------------------------------------------| +| | | Prompt maintenance alarm indication generated | Alarm indication to the remote multiplex equipment generated | AIS applied | | | +| | | | | To all the tributaries | To the composite signal | To the relevant time slots of the composite signal | +| Multiplexer and demultiplexer | Failure of power supply | Yes | | Yes (if practicable) | Yes (if practicable) | | +| Multiplexer only | Loss of incoming signal on a tributary | Yes | | | | Yes | +| Demultiplexer only | Loss of incoming signal at 6312 kbit/s | Yes | Yes | Yes | | | +| | Loss of frame alignment | Yes | Yes | Yes | | | +| | Alarm indication received from the remote multiplex equipment | | | | | | + +*Note - A Yes in the table signifies that a certain action should be taken as a consequence of the relevant fault condition. An open space in the table signifies that the relevant action should not be taken as a consequence of the relevant fault condition, if this condition is the only one present. 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This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). +- 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **CHARACTERISTICS OF DIGITAL MULTIPLEX EQUIPMENTS BASED ON A SECOND ORDER BIT RATE OF 6312 kbit/s AND USING POSITIVE JUSTIFICATION** + +*(Geneva, 1976; amended at Geneva, 1980)* + +The CCITT, + +*considering* + +- (a) that various third- and higher-order multiplex equipments exist due to the differing characteristics of networks and signal sources in those networks; +- (b) that, although studies will continue with the aim of reducing the differences between various systems, the existing situation cannot be changed in the near future; + +*recommends the following* + +(1) when countries using 1544 kbit/s primary multiplex equipments, such as the PCM multiplex equipment according to Recommendation G.733 and second-order multiplex using 6312 kbit/s according to Recommendations G.743 and G.746, are planning digital paths requiring interconnection at higher bit rates they should, when practical, utilize third-order bit rates of either 32 064 kbit/s or 44 736 kbit/s. When countries using 32 064 kbit/s third-order multiplex equipments are planning digital paths requiring interconnection at higher bit rates, they should, when practical, utilize the fourth-order bit rate of 97 728 kbit/s. + +For Figure 1/G.752 refer to Figure 1/G.702 for the basic multiplex arrangements recommended for Administrations using 1544 kbit/s primary multiplex equipment. The bit rates of terrestrial systems should accommodate multiples of 1544 kbit/s. Whenever practical, the bit rate should also accommodate a multiple of 6312 kbit/s, either 32 064 or 44 736 kbit/s, and 97 728 kbit/s; + +- (2) the characteristics of the third-order multiplex equipments using positive justification is given in § 1, below; +- (3) the characteristics of the fourth-order multiplex equipments using positive justification is given in § 2 below. + +## **1 Third-order digital multiplex equipment based on second-order bit rate of 6312 kbit/s and using positive justification** + +### **1.1 General** + +The third-order digital multiplex equipment using positive justification described below, is intended for use on digital paths and between countries using 1544 kbit/s and 6312 kbit/s primary and secondary multiplex equipments. + +A bit rate of either 32 064 kbit/s or 44 736 kbit/s is recommended to allow for the efficient and economical coding of wideband signals in the networks of Administrations using primary systems according to Recommendations G.733 and G.743. For instance for a 300 voice-circuit mastergroup (Recommendation G.233 [1]) 32 064 kbit/s is appropriate, while for a 600 voice-circuit mastergroup 44 736 kbit/s coding is appropriate. + +### **1.2 Third-order digital multiplex equipment operating at 32 064 kbit/s** + +#### **1.2.1 Bit rate** + +The nominal bit rate should be 32 064 kbit/s. The tolerance on that rate should be $\pm 10$ parts per million (ppm). + +#### 1.2.2 Frame structure + +Table 1/G.752 gives: + +- the tributary bit rate and the number of tributaries; +- the number of bits per frame; +- the bit numbering scheme; +- the bit assignment; +- the frame alignment signal. + +TABLE 1/G.752 +**32 064 kbit/s multiplexing frame structure** + +| Tributary bit rate (kbit/s) | 6312 | +|------------------------------------------------------------------------|--------------------------| +| Number of tributaries | 5 | +| Frame structure | Bit number | +| Bits for frame alignment signal (see Note 1) | Set I
1 to 5 | +| Bits from tributaries | 6 to 320 | +| $C_{j1}$ ( $j = 1$ to 5) for justification control signal (see Note 2) | Set II
1 to 5 | +| Bits from tributaries | 6 to 320 | +| $C_{j2}$ ( $j = 1$ to 5) for justification control signal (see Note 2) | Set III
1 to 5 | +| Bits from tributaries | 6 to 320 | +| Bits for frame alignment (see Note 3) | Set IV
1 to 5 | +| Bits from tributaries | 6 to 320 | +| $C_{j3}$ ( $j = 1$ to 5) for justification control signal (see Note 2) | Set V
1 to 5 | +| Bits from tributaries | 6 to 320 | +| Auxiliary bits $H_n$ ( $n = 1, 2, 3, 4, 5$ ) (see Note 4) | Set VI
1 to 5 | +| Bits from tributaries | 6 to 320 | +| Frame length | 1 920 bits | +| Bits per tributary (including justification) | 378 bits | +| Maximum justification rate per tributary | 16 700 bit/s | +| Nominal justification ratio | 0.036 | + +*Note 1* - The frame alignment signal is a 11010 pattern. + +*Note 2* - $C_{jn}$ indicates the $n$ th justification control bit of the $j$ th tributary ( $j = 1$ to 5). + +*Note 3* - The frame alignment signal is a 00101 pattern. + +*Note 4* - $H_5$ is used for transmitting failure information from the receive end to the transmit end. + +*Note 5* - The bit available for the justification of each tributary is the first slot of the tributary in set VI. + +#### 1.2.3 *Loss and recovery of frame alignment and consequent action* + +The frame alignment recovery time should not exceed 8 ms. The signal to be applied to the tributaries during the out-of-frame alignment time should be studied. + +#### 1.2.4 *Multiplexing method* + +Cyclic bit interleaving in the tributary numbering order and positive justification is recommended. + +The justification control signal should be distributed and the $C_{jn}$ -bits should be used ( $n = 1, 2, 3$ , see Table 1/G.752). + +Positive justification should be indicated by the signal 111, no justification by the signal 000. Majority decision is recommended. + +Table 1/G.752 gives the maximum justification rate per tributary and the nominal justification ratio. + +#### 1.2.5 *Jitter* + +##### 1.2.5.1 *Specifications at the input ports* + +The digital signal presented at the input ports shall be as defined in Recommendation G.703 modified by the transmission characteristic of the interconnecting cable. The input ports shall be able to tolerate a digital signal with these electrical characteristics but modified by sinusoidal jitter up to the limits specified by the amplitude frequency relationship in Figure 2/G.752. The equivalent binary content of the signal, with jitter modulation, applied to the inputs shall be a pseudo-random bit sequence of length $2^{15} - 1$ . + +*Note* - The signal with jitter modulation applied to the demultiplexer input shall contain the bits necessary for framing and justification in addition to information bits. + +![Graph showing Peak-to-peak jitter amplitude (UI) versus Jitter frequency (f). The graph shows a piecewise linear relationship with a 20 dB/decade slope. The y-axis has labels A1 and A2. The x-axis has labels f1, f2, f3, f4. The text 'CCITT - 31780' is present.](c82c7d8107cba121734a9cfba891216d_img.jpg) + +The graph shows the relationship between peak-to-peak jitter amplitude (UI) and jitter frequency (f). The y-axis is labeled 'Peak-to-peak jitter amplitude (UI)' and has two horizontal lines labeled $A_1$ and $A_2$ . The x-axis is labeled 'Jitter frequency (f)' and has four vertical lines labeled $f_1$ , $f_2$ , $f_3$ , and $f_4$ . The graph consists of three segments: a horizontal line from $f_1$ to $f_2$ at level $A_1$ , a downward-sloping line from $f_2$ to $f_3$ with a label '20 dB/decade', and a horizontal line from $f_3$ to $f_4$ at level $A_2$ . The text 'CCITT - 31780' is located at the bottom right of the graph. + +Graph showing Peak-to-peak jitter amplitude (UI) versus Jitter frequency (f). The graph shows a piecewise linear relationship with a 20 dB/decade slope. The y-axis has labels A1 and A2. The x-axis has labels f1, f2, f3, f4. The text 'CCITT - 31780' is present. + +| Input | $A_1$ (UI) | $A_2$ (UI) | $f_1$ (Hz) | $f_2$ (kHz) | $f_3$ (kHz) | $f_4$ (kHz) | +|--------------------------------|------------|------------|------------|-------------|-------------|-------------| +| 6312 kbit/s | 1 | 0.05 | 60 | 1.6 | 32 | 160 | +| 32 064 kbit/s
(provisional) | 5 | 0.05 | 60 | 1.6 | 160 | 800 | + +UI Unit interval + +FIGURE 2/G.752 +**Lower limit of maximum tolerable input jitter** + +##### 1.2.5.2 Multiplex signal output jitter + +The jitter at the 32 064 kbit/s output of the multiplexer should not exceed 0.01 UI rms. + +##### 1.2.5.3 Demultiplexer output jitter with no multiplexer or demultiplexer input jitter + +The peak-to-peak jitter at a tributary output of the demultiplexer with no jitter at the inputs should not exceed 0.2 UI. + +##### 1.2.5.4 Demultiplexer jitter transfer characteristic + +A 6312 kbit/s signal, modulated by sinusoidal jitter, should be subject to a demultiplexer jitter transfer characteristic within the gain/frequency limits given in Figure 3/G.752. + +![Figure 3/G.752: Demultiplexer transfer characteristic. A graph showing Jitter gain (dB) on the y-axis versus Jitter frequency (f) (Hz) on the x-axis. The y-axis has a value of 0.5 dB. The x-axis has values f0 and 65 Hz. The graph shows a flat line at 0.5 dB from f0 to 65 Hz, followed by a downward slope with a label '20 dB/decade'. The area above the 0.5 dB line is shaded with diagonal lines. The text 'CCITT - 31790' is at the bottom right.](e1dda754c2c88a8ad0b968aea4fc0786_img.jpg) + +The figure is a graph of Jitter gain (dB) versus Jitter frequency (f) (Hz). The y-axis is labeled 'dB' and has a value of '0,5'. The x-axis is labeled 'Jitter frequency (f)' and 'Hz', with markers for $f_0$ and '65'. The graph shows a horizontal line at 0.5 dB from $f_0$ to 65 Hz. Beyond 65 Hz, the line slopes downward with a label '20 dB/decade'. The region above the 0.5 dB line is shaded with diagonal lines. The text 'CCITT - 31790' is located at the bottom right of the graph. + +Figure 3/G.752: Demultiplexer transfer characteristic. A graph showing Jitter gain (dB) on the y-axis versus Jitter frequency (f) (Hz) on the x-axis. The y-axis has a value of 0.5 dB. The x-axis has values f0 and 65 Hz. The graph shows a flat line at 0.5 dB from f0 to 65 Hz, followed by a downward slope with a label '20 dB/decade'. The area above the 0.5 dB line is shaded with diagonal lines. The text 'CCITT - 31790' is at the bottom right. + +Note - The frequency $f_0$ should be as low as possible taking into account the limitations of measuring equipment. + +FIGURE 3/G.752 + +###### Demultiplexer transfer characteristic + +#### 1.2.6 Digital interface + +The digital interfaces at 6312 kbit/s and 32 064 kbit/s should be in accordance with Recommendation G.703. + +#### 1.2.7 Timing signal + +If it is economically feasible, it may be desirable to be able to derive the multiplexer timing signal from an external source as well as from an internal source. + +#### 1.2.8 Service digits + +The service digits are reserved for national use. + +### 1.3 Third-order digital multiplex operating at 44 736 kbit/s + +#### 1.3.1 Bit rate + +The nominal bit rate should be 44 736 kbit/s. The tolerance on that rate should be $\pm 20$ parts per million (ppm). + +#### 1.3.2 Frame structure (see Table 2/G.752). + +#### 1.3.3 Loss and recovery of frame and multiframe alignment and consequent action + +The frame alignment recovery time should not exceed 2.5 ms. The signal to be applied to the tributaries during the out-of-frame alignment time should be studied. Once frame alignment is established, multiframe alignment should be recovered in less than 250 $\mu\text{s}$ . + +#### 1.3.4 Multiplexing method + +Cyclic bit interleaving in the tributary numbering order and positive justification is recommended. + +The justification control signal should be distributed and the $C_{jn}$ -bits should be used ( $n = 1, 2, 3$ , see Table 2/G.752). + +Positive justification should be indicated by the signal 111, no justification by the signal 000. Majority decision is recommended. + +Table 2/G.752 gives the maximum justification rate per tributary and the nominal justification ratio. + +TABLE 2/G.752 + +##### **44 736-kbit/s multiplexing frame structure** + +| | | +|--------------------------------------------------------------|----------------------| +| Tributary bit rate (kbit/s) | 6312 | +| Number of tributaries | 7 | +| Frame structure (see Note 1) | Bit number | +| Bit for multiframe alignment signal ( $M_j$ ) (see Note 1) | Set I
1 | +| Bits from tributaries | 2 to 85 | +| 1st bit for frame alignment signal ( $F_{11}$ ) (see Note 2) | Set II
1 | +| Bits from tributaries | 2 to 85 | +| 1st bit for justification control signal ( $C_{j1}$ ) | Set III
1 | +| Bits from tributaries | 2 to 85 | +| 2nd bit for frame alignment signal ( $F_0$ ) | Set IV
1 | +| Bits from tributaries | 2 to 85 | +| 2nd bit for justification control signal ( $C_{j2}$ ) | Set V
1 | +| Bits from tributaries | 2 to 85 | +| 3rd bit for frame alignment signal ( $F_0$ ) | Set VI
1 | +| Bits from tributaries | 2 to 85 | +| 3rd bit for justification control signal ( $C_{j3}$ ) | Set VII
1 | +| Bits from tributaries | 2 to 85 | +| 4th bit frame alignment signal ( $F_{12}$ ) | Set VIII
1 | +| Bits from tributaries (see Note 3) | 2 to 85 | +| Frame length | 680 bits | +| Multiframe length | 4760 bits | +| Bits per tributary per multiframe (including justification) | 672 bits | +| Maximum justification rate per tributary | 9398 bit/s | +| Nominal justification ratio | 0.390 | + +*Note 1* - This frame is repeated 7 times to form a multiframe with frames designated $j = 1, 2, 3, 4, 5, 6, 7$ . The multiframe alignment signal is an XXPP010 pattern where X is a bit assigned to service function, and P is the parity bit for the preceding multiframe (i.e. from $M_1$ to $M_7$ ). P = 1 if the number of marks in all tributary bits in the preceding multiframe is odd, P = 0 if the number of marks in all tributary bits in the preceding multiframe is even. Note that the two X bits are identical in any multiframe, as are the two P bits. + +Note 2 - The frame alignment signal is $F_0 = 0$ and $F_{11} = F_{12} = 1$ . + +Note 3 - The bit available for the justification of tributary $j$ is the first slot of tributary $j$ following $F_{12}$ in the $j$ th frame. + +#### 1.3.5 Jitter + +##### 1.3.5.1 Specifications at the input ports + +The digital signal presented at the input ports shall be as defined in Recommendation G.703 modified by the transmission characteristic of the interconnecting cable. The input ports shall be able to tolerate a digital signal with these electrical characteristics but modified by sinusoidal jitter up to the limits specified by the amplitude frequency relationship in Figure 4/G.752. The equivalent binary content of the signal, with jitter modulation, applied to the inputs shall be a pseudo-random bit sequence of length $2^{15} - 1$ . + +Note - The signal with jitter modulation applied to the demultiplexer input shall contain the bits necessary for framing and justification in addition to information bits. + +![Figure 4/G.752: Lower limit of maximum tolerable input jitter. A graph showing Peak-to-peak jitter amplitude (UI) on the y-axis versus Jitter frequency (f) on the x-axis. The graph shows a piecewise linear relationship: from f1 to f2, the amplitude is constant at A1; from f2 to f3, the amplitude decreases with a slope of 20 dB/decade; from f3 to f4, the amplitude is constant at A2. The x-axis is labeled with f1, f2, f3, and f4. The y-axis is labeled with A1 and A2. The text 'CCITT - 31800' is present at the bottom right of the graph.](27b22513fc27a0ff5f230b062ad3112f_img.jpg) + +Figure 4/G.752: Lower limit of maximum tolerable input jitter. A graph showing Peak-to-peak jitter amplitude (UI) on the y-axis versus Jitter frequency (f) on the x-axis. The graph shows a piecewise linear relationship: from f1 to f2, the amplitude is constant at A1; from f2 to f3, the amplitude decreases with a slope of 20 dB/decade; from f3 to f4, the amplitude is constant at A2. The x-axis is labeled with f1, f2, f3, and f4. The y-axis is labeled with A1 and A2. The text 'CCITT - 31800' is present at the bottom right of the graph. + +| Input | $A_1$ (UI) | $A_2$ (UI) | $f_1$ (Hz) | $f_2$ (kHz) | $f_3$ (kHz) | $f_4$ (kHz) | +|---------------|------------|------------|------------|-------------|-------------|-------------| +| 6312 kbit/s | 2 | 0.05 | 10 | 0.6 | 24 | 120 | +| 44 736 kbit/s | 14 | 0.05 | 10 | 3.2 | 900 | 4500 | + +UI Unit interval + +FIGURE 4/G.752 + +###### Lower limit of maximum tolerable input jitter + +##### 1.3.5.2 Multiplex signal output jitter + +The jitter at the 44 736 kbit/s multiplexer output should not exceed 0.01 UI rms. + +##### 1.3.5.3 Demultiplexer output jitter with no multiplexer or demultiplexer input jitter + +With no jitter at the input to the multiplexer and demultiplexer, the jitter at the demultiplexer output should not exceed 1/5 UI peak-to-peak. + +##### 1.3.5.4 Demultiplexer jitter transfer characteristic + +The gain of the jitter transfer characteristic should not exceed the limits given in Figure 5/G.752. + +![Figure 5/G.752: Demultiplexer jitter transfer characteristic. A graph showing Jitter gain (dB) on the y-axis versus Jitter frequency (f) on the x-axis. The y-axis has a value of 0.1 dB. The x-axis has markers for f0, 0.5, 2.5, and 15 kHz. The graph shows a flat region at 0.1 dB from f0 to 0.5 kHz, followed by a 40 dB/decade roll-off until 2.5 kHz, and then a 20 dB/decade roll-off until 15 kHz. The area above the curve is shaded with diagonal lines. The text 'CCITT - 31810' is at the bottom right.](91be14371a97fb5ce9eeb29ae18d07c3_img.jpg) + +The figure is a plot of Jitter gain in dB against Jitter frequency (f) in kHz. The y-axis has a horizontal line at 0.1 dB. The x-axis has vertical lines at $f_0$ , 0.5, 2.5, and 15 kHz. The gain is constant at 0.1 dB from $f_0$ to 0.5 kHz. At 0.5 kHz, the gain begins to decrease with a slope of 40 dB/decade until it reaches 2.5 kHz. At 2.5 kHz, the slope changes to 20 dB/decade, continuing until 15 kHz. The region above the gain curve is shaded with diagonal lines. The text 'CCITT - 31810' is located at the bottom right of the graph. + +Figure 5/G.752: Demultiplexer jitter transfer characteristic. A graph showing Jitter gain (dB) on the y-axis versus Jitter frequency (f) on the x-axis. The y-axis has a value of 0.1 dB. The x-axis has markers for f0, 0.5, 2.5, and 15 kHz. The graph shows a flat region at 0.1 dB from f0 to 0.5 kHz, followed by a 40 dB/decade roll-off until 2.5 kHz, and then a 20 dB/decade roll-off until 15 kHz. The area above the curve is shaded with diagonal lines. The text 'CCITT - 31810' is at the bottom right. + +Note - The frequency $f_0$ should be as low as possible taking into account the limitations of measuring equipment. + +FIGURE 5/G.752 + +###### Demultiplexer transfer characteristic + +#### 1.3.6 Digital interfaces + +The digital interfaces at 6312 kbit/s and 44 736 kbit/s should be in accordance with Recommendation G.703. + +#### 1.3.7 Timing signal + +If it is economically feasible, it may be desirable to be able to derive the multiplexer timing signal from an external source as well as from an internal source. + +#### 1.3.8 Service digits + +The service digits are reserved for national use. + +## 2 Fourth-order multiplex equipment operating at 97 728 kbit/s + +### 2.1 Bit rate + +The nominal bit rate should be 97 728 kbit/s. The tolerance on that rate should be $\pm 10$ parts per million (ppm). + +### 2.2 Frame structure + +Table 3/G.752 gives: + +- the tributary bit rate and the number of tributaries; +- the number of bits per frame; +- the bit numbering scheme; +- the bit assignment; +- the frame alignment signal. + +### 2.3 Loss and recovery of frame alignment and consequent action + +The mean frame alignment recovery time should not exceed 1 ms. + +The signal to be applied to the tributaries during the out-of-frame alignment time should be all 1s pattern. + +### 2.4 Multiplexing method + +Cyclic bit interleaving in the tributary numbering order and positive justification is recommended. + +The justification control signal should be distributed and the $C_{jn}$ -bits should be used ( $n = 1, 2, 3$ , see Table 3/G.752). + +Positive justification should be indicated by the signal 111, no justification by the signal 000. Majority decision is recommended. + +Table 3/G.752 gives the maximum justification rate per tributary and the nominal justification ratio. + +TABLE 3/G.752 +**97 728 kbit/s multiplexing frame structure** + +| | | +|-------------------------------------------------------------------------------|--------------------------------------| +| Tributary bit rate (kbit/s) | 32 064 | +| Number of tributaries | 3 | +| Frame structure | Bit number | +| Frame alignment signal (110)
Bits from tributaries | Set I
1 to 3
4 to 192 | +| Justification control bits $C_{j1}$ (see Note 1)
Bits from tributaries | Set II
1 to 3
4 to 192 | +| For justification control bits $C_{j2}$ (see Note 1)
Bits from tributaries | Set III
1 to 3
4 to 192 | +| Frame alignment signal (001)
Bits from tributaries | Set IV
1 to 3
4 to 192 | +| Justification control bits $C_{j3}$ (see Note 1)
Bits from tributaries | Set V
1 to 3
4 to 92 | +| Auxiliary bits $H_n$ ( $n = 1, 2, 3$ ) (see Note 2)
Bits from tributaries | Set VI
1 to 3
4 to 192 | +| Frame length | 1 152 bits | +| Bits per tributary per frame (including justification) | 378 bits | +| Maximum justification rate per tribute | 84 833 bits | +| Nominal justification ratio | 0.035 | + +*Note 1* - $C_{jn}$ indicates the $n$ th justification bit of the $j$ th tributary ( $j = 1, 2, 3$ ). + +*Note 2* - This signal is $H_1 H_2 H_3$ pattern where $H_1$ is the parity bit for the preceding frame, and $H_2$ is a bit reserved for national use, and $H_3$ is a bit to transmit the failure information from the receiving end to the transmitting end. + +*Note 3* - The bit available for justification of tributary $j$ is the first slot of tributary $j$ following $H_n$ . + +### 2.5 Jitter + +#### 2.5.1 Specifications at the input ports + +The digital signal presented at the input ports shall be as defined in Recommendation G.703 modified by the transmission characteristic of the interconnecting cable. The input ports shall be able to tolerate a digital signal with these electrical characteristics but modified by sinusoidal jitter up to the limits specified by the amplitude frequency relationship in Figure 6/G.752. The equivalent binary content of the signal, with jitter modulation, applied to the inputs shall be a pseudo-random bit sequence of length $2^{15} - 1$ . + +*Note* - The signal with jitter modulation applied to the demultiplexer input shall contain the bits necessary for framing and justification in addition to information bits. + +![Graph showing Peak-to-peak jitter amplitude (UI) versus Jitter frequency (f). The graph shows a piecewise linear relationship with a 20 dB/decade slope. The amplitude is constant at A1 from f1 to f2, then decreases linearly to A2 at f3, and remains constant at A2 from f3 to f4. The x-axis is labeled 'Jitter frequency (f)' and the y-axis is labeled 'Peak-to-peak jitter amplitude (UI)'. The text 'CCITT - 31700' is present at the bottom right.](b712e7522f1bb7135730c7d1abb46d43_img.jpg) + +Graph showing Peak-to-peak jitter amplitude (UI) versus Jitter frequency (f). The graph shows a piecewise linear relationship with a 20 dB/decade slope. The amplitude is constant at A1 from f1 to f2, then decreases linearly to A2 at f3, and remains constant at A2 from f3 to f4. The x-axis is labeled 'Jitter frequency (f)' and the y-axis is labeled 'Peak-to-peak jitter amplitude (UI)'. The text 'CCITT - 31700' is present at the bottom right. + +| Input | $A_1$ (UI) | $A_2$ (UI) | $f_1$ (Hz) | $f_2$ (kHz) | $f_3$ (kHz) | $f_4$ (kHz) | +|---------------|------------|------------|------------|-------------|-------------|-------------| +| 32 064 kbit/s | 2 | 0.2 | 10 | 0.8 | 8 | 400 | +| 97 728 kbit/s | 6 | 0.1 | 10 | 5.5 | 325 | 1000 | + +UI Unit interval + +FIGURE 6/G.752 +**Lower limit of maximum tolerable input jitter + (provisional)** + +#### 2.5.2 Multiplex signal output jitter + +The jitter at the 97 728 kbit/s output of the multiplexer should not exceed 0.01 UI rms. + +#### 2.5.3 Demultiplexer output jitter with no multiplexer or demultiplexer input jitter + +The peak-to-peak jitter at a tributary output of the demultiplexer with no jitter at the inputs should not exceed 0.25 UI. + +#### 2.5.4 Demultiplexer jitter transfer characteristic + +A 32 064 kbit/s signal, modulated by sinusoidal jitter, should be subject to a demultiplexer jitter transfer characteristic within the gain/frequency limits given in Figure 7/G.752. + +![Figure 7/G.752: Demultiplexer transfer characteristic graph. The y-axis is 'Jitter gain' in dB, with a value of 0.5 marked. The x-axis is 'Jitter frequency (f)' in Hz, with markers for f0 and 320. The graph shows a horizontal line at 0.5 dB from f0 to 320 Hz, followed by a downward-sloping line with a label '20 dB/decade'. The area above the horizontal part of the graph is shaded with diagonal lines. The text 'CCITT - 31 791' is at the bottom right of the graph.](f176174c2978785e86a8352bd45e322e_img.jpg) + +Figure 7/G.752: Demultiplexer transfer characteristic graph. The y-axis is 'Jitter gain' in dB, with a value of 0.5 marked. The x-axis is 'Jitter frequency (f)' in Hz, with markers for f0 and 320. The graph shows a horizontal line at 0.5 dB from f0 to 320 Hz, followed by a downward-sloping line with a label '20 dB/decade'. The area above the horizontal part of the graph is shaded with diagonal lines. The text 'CCITT - 31 791' is at the bottom right of the graph. + +*Note* - The frequency $f_0$ should be as low as possible taking into account the limitations of measuring equipment. + +FIGURE 7/G.752 + +##### Demultiplexer transfer characteristic + +### 2.6 Digital interface + +The digital interfaces at 32 064 kbit/s and 97 728 kbit/s should be in accordance with Recommendation G.703. + +### 2.7 Service digits + +The service digits are reserved for national use. + +# Reference + +- [1] CCITT Recommendation *Recommendations concerning translating equipments*, Vol. III, Rec. G.233. \ No newline at end of file diff --git a/marked/G/T-REC-G.755-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.755-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..cdf3a1fb8bbc3616902030893b2c45c0c9f3e0c6 --- /dev/null +++ b/marked/G/T-REC-G.755-198811-I_PDF-E/raw.md @@ -0,0 +1,239 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' in a bold, sans-serif font. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.755** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**GENERAL ASPECTS OF DIGITAL TRANSMISSION +SYSTEMS** + +**TERMINAL EQUIPMENTS** + +--- + +**DIGITAL MULTIPLEX EQUIPMENT +OPERATING AT 139 264 kbit/s AND +MULTIPLEXING THREE TRIBUTARIES +AT 44 736 kbit/s** + +**ITU-T Recommendation G.755** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.755 was published in Fascicle III.4 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **DIGITAL MULTIPLEX EQUIPMENT OPERATING AT 139 264 KBIT/S AND MULTIPLEXING THREE TRIBUTARIES AT 44 736 KBIT/S** + +*(Melbourne, 1988)* + +## **1 General** + +The digital multiplex equipment described in this Recommendation is intended for use between networks using different digital hierarchies as specified in Recommendations G.702 and G.802. + +## **2 Bit rate** + +The bit rates of the tributary and multiplex signals should be $44\,736\text{ kbit/s} \pm 20\text{ ppm}$ and $139\,264\text{ kbit/s} \pm 15\text{ ppm}$ , respectively, as specified in Recommendation G.703. + +## **3 Frame structure** + +Table 1/G.755 gives the recommended 139 264 kbit/s multiplexing frame structure. + +## **4 Loss and recovery of frame alignment and consequent action** + +Loss of frame alignment should be assumed to have taken place when four consecutive frame alignment signals have been incorrectly received in their predicted positions. + +When frame alignment is assumed to be lost, the frame alignment device should decide that such alignment has effectively been recovered when it detects the presence of three consecutive correct frame alignment signals. + +The frame alignment device, having detected the appearance of a single correct frame alignment signal, should begin a new search for the frame alignment signal when it detects the absence of the frame alignment signal in one of the two following frames. + +*Note* - As it is not strictly necessary to specify the detailed frame alignment strategy, any suitable frame alignment strategy may be used provided the performance achieved is at least as efficient in all respects as that obtained by the above frame alignment strategy. + +## **5 Multiplexing and justification methods** + +Cyclic bit interleaving in the tributary numbering order and positive justification are recommended. + +The justification control signal should be distributed and use the $C_{ji}$ -bits ( $j = 1, 2, 3; i = 1, 2, 3, 4, 5$ ) (see Note 6 to Table 1/G.755). + +Positive justification should be indicated by the justification control signal 11111 and no justification by the signal 00000. Majority decision is recommended. + +Table 1/G.755 gives the maximum justification rate per tributary and the nominal justification ratio. + +## **6 Jitter** + +### **6.1 Demultiplexer tributary jitter transfer characteristic** + +The demultiplexer 44 736 kbit/s tributary jitter transfer characteristic should meet the gain/frequency limits given in Figure 1/G.755. The equivalent binary content of the test signal used should result in a tributary output signal of 1000. + +TABLE 1/G.755 + +#### **139 264 kbit/s multiplexing frame structure** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------| +| Nominal tributary bit rate (kbit/s) | 44 736 | +| Number of tributaries | 3 | +| Frame structure | Bit number | +| Frame alignment signal (111110100000)
Bits from tributaries | Set I
1 to 12
13 to 159 | +| Justification control bits $C_{j1}$ (Note 1)
Bits from tributaries | Set II
1 to 3
4 to 159 | +| Justification control bits $C_{j2}$ (Note 1)
Bits from tributaries | Set III
1 to 3
4 to 159 | +| Justification control bits $C_{j3}$ (Note 1)
Alarm indication to the remote multiplex equipment (Note 2)
Parity bit (Notes 3, 4 and 5)
Bits reserved for future use (Note 6)
Bits from tributaries | Set IV
1 to 3
4
5
6 to 9
10 to 159 | +| Justification control bits $C_{j4}$ (Note 1)
Bits from tributaries | Set V
1 to 3
4 to 159 | +| Justification control bits $C_{j5}$ (Note 1)
Bits from tributaries available for justification
Bits from tributaries | Set VI
1 to 3
4 to 6
7 to 159 | +| Frame length | 954 bits | +| Bits per tributary in a frame | 307 bits | +| Maximum justification rate per tributary | 146 kbit/s | +| Nominal justification ratio | 0.545 | + +*Note 1* - $C_{ji}$ ( $j = 1, 2, 3$ ; $i = 1, 2, 3, 4, 5$ ) indicates the $i$ th justification control bit of the $j$ th tributary. + +*Note 2* - See § 10.2.1. + +*Note 3* - The parity bit = 1 if the number of marks in all tributary bits including the bits in the justifiable time-slots in the preceding frame is odd; the parity bit = 0 if the number of marks in all tributary bits including the bits in the justifiable time-slots in the preceding frame is even. + +*Note 4* - It is recognized that existing multiplex equipment installed prior to adoption of this Recommendation does not insert the parity bit. + +*Note 5* - The implementation and the use of this parity bit procedure are for further study. + +*Note 6* - These bits should be set to 1 when not used. + +*Note 1* - This characteristic is usually measured between the high speed and low speed interfaces of the demultiplexer and the measurements are taken in unit intervals. It is then necessary to introduce a correction factor to account for the difference in the size of unit intervals. + +*Note 2* - In addition, the need to specify a muldex jitter transfer characteristic is for further study. + +*Note 3* - It is recognized that the existing multiplex equipment designed prior to the adoption of this Recommendation might need tributary test signals incorporating the 44 736 kbit/s frame structure defined in Recommendation G.572. + +![Figure 1/G.755: Demultiplexer tributary jitter transfer characteristic graph. The y-axis represents Jitter gain in dB, ranging from 0 to 0.1. The x-axis represents Frequency on a log scale. The graph shows a flat response at 0.1 dB from frequency f0 to fc = 1 kHz. From fc, the gain rolls off at a rate of 20 dB/decade, passing through 15 kHz. The area under the curve is shaded with diagonal lines. The label TI802260-86 is in the bottom right corner.](6de7dcb072cef2388026fb0f504084b2_img.jpg) + +The figure is a graph titled 'Demultiplexer tributary jitter transfer characteristic'. The vertical axis is labeled 'Jitter gain' and 'dB', with markings at 0 and 0.1. The horizontal axis is labeled 'Frequency (log scale)' and has markings for $f_0$ , $f_c = 1 \text{ kHz}$ , and 15 kHz. The graph shows a shaded region representing the jitter gain. From $f_0$ to $f_c$ , the gain is constant at 0.1 dB. At $f_c$ , the gain begins to roll off with a slope of 20 dB/decade. The roll-off continues until 15 kHz. The label 'TI802260-86' is located at the bottom right of the graph. + +Figure 1/G.755: Demultiplexer tributary jitter transfer characteristic graph. The y-axis represents Jitter gain in dB, ranging from 0 to 0.1. The x-axis represents Frequency on a log scale. The graph shows a flat response at 0.1 dB from frequency f0 to fc = 1 kHz. From fc, the gain rolls off at a rate of 20 dB/decade, passing through 15 kHz. The area under the curve is shaded with diagonal lines. The label TI802260-86 is in the bottom right corner. + +*Note* - The frequency $f_0$ should be as low as possible, taking into account the limitations of measuring equipment. In any case $f_0$ should be no greater than 10 Hz. The selective measurement method should be used. + +FIGURE 1/G.755 + +#### Demultiplexer tributary jitter transfer characteristic + +### 6.2 Output jitter + +#### 6.2.1 Tributary output jitter + +With no jitter applied to the input ports of the multiplexer and with the multiplexer directly connected to the demultiplexer, the peak-to-peak jitter at the tributary output port should not exceed 0.3 UI when measured over a one minute interval within the frequency range from $f_1 = 10 \text{ Hz}$ to $f_4 = 400 \text{ Hz}$ . + +When measured with an instrument incorporating a bandpass filter having a lower cutoff frequency of $f_3 = 60 \text{ kHz}$ , a roll-off of 20 dB/decade and an upper limit of $f_4 = 400 \text{ kHz}$ , the peak-to-peak output jitter should not exceed 0.05 UI when it is measured over a one minute interval. + +#### 6.2.2 Multiplexer output jitter + +The peak-to-peak jitter at the 139 264 kbit/s output port should not exceed 0.05 UI when it is measured over a one minute interval within the frequency range from 200 Hz to 3500 kHz. + +### 6.3 Input jitter + +#### 6.3.1 Tributary input jitter + +The 44 736 kbit/s input port should be capable of accommodating levels of input jitter up to the limits given in Figure 2/G.755. + +*Note* - Current Recommendation G.703 does not refer to the jitter tolerated at the digital distribution frame at 44 736 kbit/s nor at the input port of equipment connected to this distribution frame. + +![Graph showing Peak-to-peak sinusoidal jitter amplitude (log scale) versus Jitter frequency (log scale). The graph shows a constant amplitude A1 from f1 to f2, a linear decrease from A1 at f2 to A2 at f3, and a constant amplitude A2 from f3 to f4. The text 'T1808700-88' is in the bottom right corner.](431b8889a0e7f676f0eef40859590349_img.jpg) + +Graph showing Peak-to-peak sinusoidal jitter amplitude (log scale) versus Jitter frequency (log scale). The graph shows a constant amplitude A1 from f1 to f2, a linear decrease from A1 at f2 to A2 at f3, and a constant amplitude A2 from f3 to f4. The text 'T1808700-88' is in the bottom right corner. + +| Peak-to-peak sinusoidal jitter amplitude | | Frequency | | | | +|------------------------------------------|------------|------------|------------|-------------|-------------| +| $A_1$ (UI) | $A_2$ (UI) | $f_1$ (Hz) | $f_2$ (Hz) | $f_3$ (kHz) | $f_4$ (kHz) | +| 5.0 | 0.1 | 10 | 2.3 | 60 | 400 | + +FIGURE 2/G.755 + +##### **Lower limit of maximum tolerable sinusoidal input jitter at 44 736 kbit/s** + +#### 6.3.2 *Demultiplexer input jitter* + +The 139 264 kbit/s input port should be capable of accommodating levels of input jitter up to the limits given in Recommendation G.823. + +*Note* - The jitter accommodation requirement should be met when the jittered input signal is composed of the multiplexed tributary signals having any value of jitter allowed for the 44 736 kbit/s level. + +## **7 Digital interfaces** + +The digital interfaces at 44 736 kbit/s and 139 264 kbit/s should be in accordance with Recommendation G.703. + +## **8 Timing signal** + +If it is economically feasible, it may be desirable to be able to derive the multiplexing timing signal from an external source as well as from an internal source. + +## **9 Service digits** + +Six bits per frame are available for service functions (see Table 1/G.755): bit 4 of Set IV is used to transmit an alarm indication to the remote multiplex equipment when specific fault conditions are detected in the multiplex equipment when specific fault conditions are detected in the multiplex equipment (see § 10 below); bit 5 of Set IV may be used for a parity check; bits 6 to 9 of Set IV are reserved for further use. + +## 10 Fault conditions and consequent actions + +### 10.1 Fault conditions + +10.1.1 The digital multiplex equipment should detect the following fault conditions: + +- 1) failure of power supply; +- 2) loss of an incoming 44 736 kbit/s tributary signal at a multiplexer input port; +- 3) loss of an incoming 139 264 kbit/s multiplex signal at a demultiplexer input port; + +*Note* - The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. + +- 4) loss of frame alignment signal at a demultiplexer input port; +- 5) detection of an alarm indication received from the remote multiplex equipment at a demultiplexer input port; +- 6) detection of alarm indication signal (AIS) at a demultiplexer input port. + +*Note 1* - The equivalent binary content of the AIS at 139 264 kbit/s should be a continuous stream of binary 1s (marks) as recommended in Recommendation M.20. + +*Note 2* - The strategy for detecting the presence of the AIS should be such that the AIS is detectable even in the presence of an error ratio of $1 \cdot 10^{-3}$ . However, a signal with all bits except the frame alignment signal in the state of 1 should not be mistaken as an AIS. + +10.1.2 The need to monitor the degradation of the incoming 139 264 kbit/s signal for the purpose of end-to-end error performance monitoring of the 139 264 kbit/s digital block, as well as the procedure for detecting such degradation are for further study. + +### 10.2 Consequent actions + +Further to the detection of a fault condition, the appropriate actions should be taken as specified in Table 2/G.755. + +*Note 1* - The concept and definition of prompt maintenance alarm indication is given in Recommendation M.20. + +*Note 2* - When the alarm indication signal (AIS) is detected at the input of the demultiplexer, the prompt maintenance alarm indication associated with loss of frame alignment should be inhibited, while the rest of the consequent actions are in accordance with those associated in Table 2/G.755 with the fault condition. + +10.2.1 Alarm indication to the remote multiplex equipment should be generated by changing bit 4 of Set IV (see Table 1/G.755) from the state 0 to the state 1. + +10.2.2 AIS should be applied to the following as specified in Table 2/G.755: + +- all three 44 736 kbit/s tributary outputs from the demultiplexer; +- 139 264 kbit/s output of the multiplexer; +- the time slots of the 139 264 kbit/s signal at the output of the multiplexer, corresponding to the relevant 44 736 kbit/s tributary. + +*Note* - The equivalent binary content of the AIS at 44 736 kbit/s is a signal with a valid frame alignment signal, parity and justification control bits as defined in Table 2/G.752, with the tributary bits being set to a 1010 ... sequence, starting with a binary 1 after each frame alignment, multi-frame alignment and justification control bit, and with all justification control bits being set to binary 0. + +**TABLE 2/G.755** +**Fault conditions and consequent actions** + +| Equipment part | Fault condition (see § 10.1) | Consequent actions (see §10.2) | | | | | +|-------------------------------|---------------------------------------------------------------|-----------------------------------------------|--------------------------------------------------------------|------------------------|-------------------------|----------------------------------------------------| +| | | Prompt maintenance alarm indication generated | Alarm indication to the remote multiplex equipment generated | AIS applied | | | +| | | | | To all the tributaries | To the composite signal | To the relevant time slots of the composite signal | +| Multiplexer and demultiplexer | Failure of power supply | Yes | | Yes, if practicable | Yes, if practicable | | +| Multiplexer only | Loss of incoming signal on a tributary | Yes | | | | Yes | +| Demultiplexer only | Loss of incoming signal at 139 264 kbit/s | Yes | Yes | Yes | | | +| | Loss of frame alignment | Yes | Yes | Yes | | | +| | Alarm indication received from the remote multiplex equipment | | | | | | + +*Note - A Yes in the table signifies that a certain action should be taken as a consequence of the relevant fault condition. An open space in the table signifies that the relevant action should not be taken as a consequence of the relevant fault condition, if this condition is the only one present. If more than one fault condition is simultaneously present the relevant action should be taken if, for at least one of the conditions, a Yes is defined in relation to this action.* \ No newline at end of file diff --git a/marked/G/T-REC-G.7714-200508-I_PDF-E/raw.md b/marked/G/T-REC-G.7714-200508-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..83948708429bba78e4f8b07784ed78542cd80993 --- /dev/null +++ b/marked/G/T-REC-G.7714-200508-I_PDF-E/raw.md @@ -0,0 +1,806 @@ + + +**ITU-T** + +**G.7714/Y.1705** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(08/2005) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Data over Transport – Generic aspects – Transport +network control aspects + +SERIES Y: GLOBAL INFORMATION +INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS +AND NEXT-GENERATION NETWORKS + +Internet protocol aspects – Operation, administration and +maintenance + +# --- **Generalized automatic discovery for transport entities** + +ITU-T Recommendation G.7714/Y.1705 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| General | G.7000–G.7099 | +| Transport network control aspects | G.7700–G.7799 | +| ETHERNET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.7714/Y.1705** + +# **Generalized automatic discovery for transport entities** + +## **Summary** + +This Recommendation describes the discovery process for transport entities, their sub-processes and basic interactions in a protocol-neutral manner. + +## **Source** + +ITU-T Recommendation G.7714/Y.1705 was approved on 22 August 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. + +## **Keywords** + +Auto-discovery, discovery agent, layer adjacency discovery, transport capability exchange. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2006 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +| | Page | +|--------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Terms and definitions ..... | 2 | +| 4 Abbreviations..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Discovery process overview ..... | 3 | +| 7 Discovery trigger process ..... | 4 | +| 8 Layer Adjacency Discovery (LAD)..... | 4 | +| 8.1 Methods for layer adjacency discovery ..... | 5 | +| 8.2 Timescales for layer adjacency discovery ..... | 6 | +| 9 Transport entity capability exchange..... | 7 | +| 10 Requirements ..... | 8 | +| 10.1 Discovery agent ..... | 8 | +| 10.2 (T)CPs under the responsibility of a Discovery Agent ..... | 8 | +| 10.3 Discovery process instance..... | 8 | +| 10.4 Discovery of a transport entity ..... | 8 | +| 10.5 Discovery of a unidirectional transport entity ..... | 9 | +| 10.6 Discovery of a bidirectional transport entity ..... | 9 | +| 10.7 Discovery of transport entity capabilities..... | 9 | +| 11 Discovery messages..... | 9 | +| 11.1 LAD process ..... | 10 | +| 11.2 TCE process..... | 11 | +| 12 Discovery state machine descriptions..... | 11 | +| 12.1 LAD state machine ..... | 12 | +| 12.2 TCE state machine..... | 15 | +| Appendix I – Discovery process state machines..... | 19 | +| Appendix II – Mapping of TCE state machine to RFC 1661 LCP state machine ..... | 21 | +| Appendix III – Rationale for removal of CELA process ..... | 22 | + + + +# **Generalized automatic discovery for transport entities** + +# **1 Scope** + +This Recommendation describes the discovery process for transport entities (Link Connection, Trail and Network Connection). Their sub-processes and basic interactions within the Discovery process are described in a protocol-neutral manner. Other aspects of discovery, such as further specification of mechanisms, protocols and how discovery may be used by applications, is outside the scope of this Recommendation. This version of ITU-T Rec. G.7714/Y.1705 allows the discovery process to be used by the Management Plane as well as the Control Plane1. + +In this Recommendation, the Discovery Agent is broken down into the following discovery processes: + +- a) Discovery Trigger; +- b) Layer Adjacency Discovery; +- c) Transport Entity Capability Exchange. + +# **2 References** + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- ITU-T Recommendation G.805 (2000), *Generic functional architecture of transport networks*. +- ITU-T Recommendation G.806 (2004), *Characteristics of transport equipment – Description methodology and generic functionality*. +- ITU-T Recommendation G.852.2 (1999), *Enterprise viewpoint description of transport network resource model*. +- ITU-T Recommendation G.853.1 (1999), *Common elements of the information viewpoint for the management of a transport network*. +- ITU-T Recommendation M.3100 (2005), *Generic network information model*. +- ITU-T Recommendation G.8080/Y.1304 (2001), *Architecture for the automatically switched optical network (ASON)*, plus Amendment 2 (2005). + +--- + +1 The 2001 version of ITU-T Rec. G.7714/Y.1705 assumed discovery was limited to use by the Control Plane. + +# 3 Terms and definitions + +This Recommendation makes use of the following terms defined in other ITU-T Recommendations. + +- 3.1 **Access Point (AP)**: See ITU-T Rec. G.805. +- 3.2 **Connection Termination Point (CTP)**: See ITU-T Rec. M.3100. +- 3.3 **continuity supervision**: See ITU-T Rec. G.806. +- 3.4 **Discovery Agent (DA)**: See ITU-T Rec. G.8080/Y.1304. +- 3.5 **link**: See ITU-T Recs G.852.2 and G.853.1. +- 3.6 **link connection**: See ITU-T Rec. G.805. +- 3.7 **network connection**: See ITU-T Rec. G.805. +- 3.8 **Subnetwork Point (SNP)**: See ITU-T Rec. G.8080/Y.1304. +- 3.9 **trail**: See ITU-T Rec. G.805. +- 3.10 **Trail Termination Point (TTP)**: See ITU-T Rec. M.3100. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +- AP Access Point +- CI Characteristic Information +- CP Connection Point +- CTP Connection Termination Point +- DA Discovery Agent +- DCN Data Communication Network +- DT Discovery Trigger +- ID Identifier +- LAD Layer Adjacency Discovery +- LC Link Connection +- LCP Link Control Protocol +- LRM Link Resource Manager +- MS Multiplexing Section +- NC Network Connection +- NE Network Element +- PPP Point-to-Point Protocol +- RS Regenerator Section +- Rx Receive +- SNP Subnetwork Point +- TAP Termination and Adaptation Performer +- TCE Transport Entity Capability Exchange +- TCP Termination Connection Point + +TTP Trail Termination Point + +Tx Transmit + +VC Virtual Container + +# 5 Conventions + +In this Recommendation the notation "R-n" is used to identify requirements. + +The notation (T)CP is used to represent a TCP or a CP. + +# 6 Discovery process overview + +The overall discovery process for transport entities is illustrated in Figure 6-1. It is a generic process that is applicable to any layer of multilayer networks as described in ITU-T Rec. G.805. + +There is no proscribed location or distribution for the entities that support the discovery process (e.g., management systems, NEs, etc.). It shall be possible for the Management Plane to enable and disable the discovery process and individual sub-processes that will be discussed in subsequent clauses. + +As shown in Figure 6-1, the discovery process is documented for the three sub-processes: Discovery Trigger (DT), Layer Adjacency Discovery (LAD) and Transport Entity Capability Exchange (TCE)2. + +- The DT process is responsible for triggering the LAD and TCE processes. The DT process is realized through the Discovery Agent (DA). +- The LAD process is used for deriving an association between two TCPs/CPs that form a network connection/link connection in a particular layer network. The association discovered through layer adjacency discovery is valid as long as the trail supporting the link connection is valid. Preconditions of the LAD process include knowledge of the (T)CP IDs. +- The TCE process is used for exchanging information about the capabilities of the transport entities (e.g., Link Connections, Trails) in order to facilitate the negotiation of an agreed set of capabilities. Preconditions of the TCE process include knowledge of the Layer Adjacency information and the local capabilities information. + +NOTE – If Layer Adjacency has been preconfigured, the LAD process may be omitted. + +--- + +2 TCE was called SCE (Service Capability Exchange) in ITU-T Rec. G.7714/Y.1305 (2001). + +![Figure 6-1/G.7714/Y.1705 – Discovery sub-process interaction diagram. The diagram shows four main entities: DT_A, LAD_A, TCE_A, and DT_Z, LAD_Z, TCE_Z. DT_A and DT_Z are on the left and right respectively, connected to LAD_A, LAD_Z, TCE_A, and TCE_Z. LAD_A and LAD_Z exchange DiscMsg and DiscAckMsg. TCE_A and TCE_Z exchange TCECapReqMsg, TCECapAckMsg, and TCECapNackMsg. DT_A and DT_Z send Start/Stop and Notify messages to the other entities.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +The diagram illustrates the interaction between discovery sub-processes at two ends, A and Z. At end A, there are three sub-processes: DTA, LADA, and TCEA. At end Z, there are three sub-processes: DTZ, LADZ, and TCEZ. DTA and DTZ are connected to LADA, LADZ, TCEA, and TCEZ via 'Start/Stop' and 'Notify' messages. LADA and LADZ exchange 'DiscMsg(ATX)', 'DiscAckMsg(ARX)', 'DiscMsg(ZTX)', and 'DiscAckMsg(ZRX)' messages. TCEA and TCEZ exchange 'TCECapReqMsg(ATX)', 'TCECapAckMsg/ TCECapNackMsg(ARX)', 'TCECapReqMsg(ZTX)', and 'TCECapAckMsg/ TCECapNackMsg(ZRX)' messages. The diagram is labeled G.7714/Y.1705\_F6-1. + +Figure 6-1/G.7714/Y.1705 – Discovery sub-process interaction diagram. The diagram shows four main entities: DT\_A, LAD\_A, TCE\_A, and DT\_Z, LAD\_Z, TCE\_Z. DT\_A and DT\_Z are on the left and right respectively, connected to LAD\_A, LAD\_Z, TCE\_A, and TCE\_Z. LAD\_A and LAD\_Z exchange DiscMsg and DiscAckMsg. TCE\_A and TCE\_Z exchange TCECapReqMsg, TCECapAckMsg, and TCECapNackMsg. DT\_A and DT\_Z send Start/Stop and Notify messages to the other entities. + +**Figure 6-1/G.7714/Y.1705 – Discovery sub-process interaction diagram** + +The following clauses describe in detail the sub-processes that encompass discovery, i.e., DT, LAD and TCE. A detailed description of the interfaces and message exchanges is provided in clause 11. + +# 7 Discovery trigger process + +The discovery trigger process is enabled by the Management Plane, which specifies the types of scenarios that need to be supported. The scenario profile has multiple parameters including whether or not particular discovery sub-processes are supported, what type, under what conditions, and what management information needs to be provided under each condition. The default profile is a policy decision. For example: + +- Whether LAD is used. If LAD is not used, the Management Plane shall provide (T)CP binding information. If LAD is used, what type (Type 1 or Type 2 as described in 8.1), and under what conditions (return-to-service triggered or continuous as described in 8.2). +- Whether TCE is used. If TCE is not used, the Management Plane shall provide local and remote end information. If TCE is used, the detailed capabilities of the end point transport entities shall be provided, as governed by policy. + +# 8 Layer Adjacency Discovery (LAD) + +The discovery process for transport entities takes place on a per-layer basis, consistent with ITU-T Rec. G.805. The LAD process is used to discover the association between the end points of a link connection (LC) or network connection (NC) within a particular layer (i.e., between the two TCP/CPs that constitute a connection). A pre-condition for the discovery process is that (T)CP IDs shall exist for the end points being discovered. It shall be possible for the Management Plane to enable and disable the LAD process on a per-(T)CP basis. + +The LAD process involves the sending of discovery and discovery acknowledgement messages between the end points of a LC or NC in a particular layer, shown as "A" and "Z" in Figure 6-1. The LAD process at the A-end starts by periodically sending discovery messages to the Z-end containing information that allows the Z-end to determine the A-end's (T)CP ID and the Discovery Agent (DA) ID scoping the (T)CP ID. When the Z-end has received that message, it sends a discovery acknowledgement message back to the A-end that contains: + +- the information the Z-end has received from the A-end; + +– the information about the Z-end where the discovery message was received. + +The exchanged information allows both sides to identify the A-Z unidirectional connection. This process is performed in parallel for the Z-A direction to identify the Z-A unidirectional connection. + +After both unidirectional connections associated with a (T)CP have been identified, the unidirectional links are verified to be between the same pair of (T)CPs. If they are not, a misconnection is detected and reported. If the two unidirectional links are between the same pair of (T)CPs, the LAD process is assumed to be complete. The Management Plane may then stop the LAD process or keep it active to continually supervise the adjacency. + +![Diagram illustrating Layer adjacency discovery (LAD) between two client layers connected via a server layer trail. The diagram shows three layers: Client layer (top), Server layer (middle), and Network layer (bottom). Two client layers are connected via a 'Client layer link' composed of three 'Client layer LCs'. Each client layer is connected to an 'AP' (Access Point) in the server layer. The two APs are connected by a 'Server layer trail'. Below the APs are 'Server layer network connections' to the network layer. On the left, two callouts show the internal structure of a client layer node: the top one shows SNP (G.8080/Y.1304), CP (G.805), and CTP (M.3100); the bottom one shows TTP (M.3100), TCP (G.805), and SNP (G.8080/Y.1304). The diagram is labeled G.7714/Y.1705_F8-1.](5a4e62bead259c258d069fd3663ea670_img.jpg) + +Diagram illustrating Layer adjacency discovery (LAD) between two client layers connected via a server layer trail. The diagram shows three layers: Client layer (top), Server layer (middle), and Network layer (bottom). Two client layers are connected via a 'Client layer link' composed of three 'Client layer LCs'. Each client layer is connected to an 'AP' (Access Point) in the server layer. The two APs are connected by a 'Server layer trail'. Below the APs are 'Server layer network connections' to the network layer. On the left, two callouts show the internal structure of a client layer node: the top one shows SNP (G.8080/Y.1304), CP (G.805), and CTP (M.3100); the bottom one shows TTP (M.3100), TCP (G.805), and SNP (G.8080/Y.1304). The diagram is labeled G.7714/Y.1705\_F8-1. + +**Figure 8-1/G.7714/Y.1705 – Layer adjacency discovery – Example** + +The example in Figure 8-1 illustrates discovery processes applied in both the client and server layers to discover layer network topology. Two APs that are associated over a server layer network connection form a trail at the server layer. In this example, the server layer trail supports the association of three pairs of CPs in the client layer to form a client layer link composed of three LCs. Here the LAD process discovers the association between the two TCPs in the server layer as well as the relationships between the CPs in the client layer. The associations established at the two layers are valid only as long as the supporting server layer network connection is valid. + +NOTE 1 – The physical media layer is conceptually no different from any other transport entity layer adjacency. In the 2001 version of ITU-T Rec. G.7714/Y.1705, this was called PMAD (Physical Media Adjacency Discovery). + +NOTE 2 – The LAD process for multilayer networks may be optimized by deriving the client layer adjacencies from the discovered server layer adjacencies, using the TCE information provided by the TCE process. + +## 8.1 Methods for layer adjacency discovery + +The discovery methodology uses the processes defined in the following clauses to determine the TCP-to-TCP relationship. Once the TCP-to-TCP relationship has been determined, the CP-to-CP connectivity relationships are derived using local information. Two types of discovery methodology + +are available for supporting Layer Adjacency Discovery, one involving usage of the server layer trail overhead (Type 1) and the other utilizing the client layer payload area (Type 2). + +![Diagram illustrating Type 1 and Type 2 Layer Adjacency Discovery (LAD) processes. The diagram shows two stacks of network layers. The top stack represents the Client layer, containing TCP1A, CP2A, CP2Z, and TCP1Z. The bottom stack represents the Server layer, containing TCP3A and TCP3Z. Type 2 discovery (blue arrow) is shown in the Client layer, using the client payload to discover CP2A and CP2Z. Type 1 discovery (blue arrow) is shown in the Server layer, using trail overhead to discover TCP3A and TCP3Z. Dashed lines labeled 'derived' show the relationship between TCPs and CPs. A red arrow labeled 'LC being discovered' points from CP2A to CP2Z. A label 'G.7714/Y.1705_F8-2' is in the bottom right.](007b053fe94a8348f75128a584503fd0_img.jpg) + +Diagram illustrating Type 1 and Type 2 Layer Adjacency Discovery (LAD) processes. The diagram shows two stacks of network layers. The top stack represents the Client layer, containing TCP1A, CP2A, CP2Z, and TCP1Z. The bottom stack represents the Server layer, containing TCP3A and TCP3Z. Type 2 discovery (blue arrow) is shown in the Client layer, using the client payload to discover CP2A and CP2Z. Type 1 discovery (blue arrow) is shown in the Server layer, using trail overhead to discover TCP3A and TCP3Z. Dashed lines labeled 'derived' show the relationship between TCPs and CPs. A red arrow labeled 'LC being discovered' points from CP2A to CP2Z. A label 'G.7714/Y.1705\_F8-2' is in the bottom right. + +**Figure 8-2/G.7714/Y.1705 – Type 1 and Type 2 LAD** + +In the Type 1 Discovery process, the server layer trail overhead is used to discover the peer TCPs (e.g., TCP3A to TCP3Z in Figure 8-2). The server layer trail overhead is used to carry the discovery message. The CP-to-CP relationships are derived from the TCP-to-TCP relationships using local knowledge of the configuration of the adaptation function and its relationship with the trail termination function. + +The Type 2 Discovery Process transmits a discovery message in the client layer payload to discover the peer TCPs (e.g., TCP1A to TCP1Z in Figure 8-2). The CP-to-CP relationship is derived from the local knowledge of the matrix connection that was previously set up to connect the test signal to the desired CP (shown in Figure 8-2). + +## 8.2 Timescales for layer adjacency discovery + +The layer adjacency discovery process is responsible for discovering the binding of a local (T)CP to a remote (T)CP created by the transport entity connecting them. There are two different approaches that can be taken regarding when the LAD process needs to be run. + +### 8.2.1 Return-to-service triggered + +Many transport technologies manifest certain behaviour whereby it is impossible to change the endpoints of a transport entity without causing a continuity failure (as detected by continuity supervision). When the continuity failure occurs, the transport entity will become operationally out-of-service and the LAD information is invalidated. When the continuity failure is removed, the transport entity will become operationally in-service, and the binding of local and remote (T)CPs needs to be rediscovered. This transition is used to cause the LAD state machine to relearn the binding. + +### 8.2.2 Continuous + +Cases also exist where continuous operation of the LAD process is necessary; for example, where no continuity supervision is performed. In such cases, the (T)CP binding created by the transport entity needs to be continually relearned and reviewed for any changes. + +# 9 Transport entity capability exchange + +The TCE process exchanges messages to notify the transport entities at either end about the functional capabilities that they are willing to support. These capabilities include supported adaptation(s), Characteristic Information etc., associated with the two adjacent (T)CPs. Unlike the LAD process, this is a multi-stage process wherein the network elements at both ends of the link negotiate a set of capabilities that each is willing to support. + +As described earlier, and illustrated in Figure 9-1 below, TCE information can be combined with the results of the LAD process to derive potential client layer CPs. + +The capabilities exchanged are listed in 11.2. + +![Diagram illustrating Transport entity capability exchange. The top part shows three Client Points (CP 1, CP 2, CP 3) on each side connected by arrows labeled 'Information exchange over DCN' and 'CP association inferred'. The bottom part shows two network elements (represented by inverted triangles) connected by an arrow labeled 'TCP association discovered' and 'Needs at least one in-band event'. A small note 'G.7714/Y.1705_F9-1' is present near the bottom right.](ddc7460821484f1ae2835c67955c554c_img.jpg) + +The diagram illustrates the Transport entity capability exchange process. It is divided into two horizontal sections. The top section shows two groups of three green circles, labeled CP 1, CP 2, and CP 3 from top to bottom. Each group is enclosed in an oval. Three horizontal double-headed arrows connect the corresponding circles in the left and right groups. The top arrow is labeled 'Information exchange over DCN' and the bottom arrow is labeled 'CP association inferred'. The middle arrow is unlabeled. The bottom section shows two network elements, each represented by an inverted triangle with three small circles above it. Below each triangle is a vertical line connecting to a small oval containing a green circle. A horizontal double-headed arrow connects these two ovals, labeled 'TCP association discovered' and 'Needs at least one in-band event'. A small note 'G.7714/Y.1705\_F9-1' is present near the bottom right of the diagram. + +Diagram illustrating Transport entity capability exchange. The top part shows three Client Points (CP 1, CP 2, CP 3) on each side connected by arrows labeled 'Information exchange over DCN' and 'CP association inferred'. The bottom part shows two network elements (represented by inverted triangles) connected by an arrow labeled 'TCP association discovered' and 'Needs at least one in-band event'. A small note 'G.7714/Y.1705\_F9-1' is present near the bottom right. + +**Figure 9-1/G.7714/Y.1705 – Transport entity capability exchange – Example** + +The TCE processes at each end start by the transmission of TCECapReqMsg messages (as shown in Figure 6-1) containing the capabilities that the local end point supports. When the message is received by the TCE process for the remote end point, it compares the list of capabilities it has received with the ones it is willing to support, and if not matched, it sends a TCECapNackMsg with a modified set of capabilities that it is willing to support. The originating end, on receiving this modified capabilities set, can either agree to support this set of capabilities by sending a TCECapAckMsg, or negotiate further by transmitting a new TCECapReqMsg with a new and modified set of capabilities. Once both ends agree upon a set of capabilities, each end will stop transmission of these capability messages. + +It should be noted that the capabilities exchanged could be asymmetric across the two directions of a bidirectional link. + +# **10 Requirements** + +## **10.1 Discovery agent** + +- R-1 The Discovery Agent shall discover the link topology supported by its set of (T)CPs. +- R-2 The Discovery Agent shall have a unique identifier within the operational region where the Discovery process may be run +- R-3 The link topology information for a (T)CP shall be provided by the Discovery Agent to corresponding registered control/management entities. + +## **10.2 (T)CPs under the responsibility of a Discovery Agent** + +- R-4 The (T)CP shall have a unique identifier within the scope of the local (or responsible) Discovery Agent. +- R-5 A discovery process instance shall exist for each (T)CP managed by the Discovery Agent. + +The following definition applies to all remaining requirements: the (T)CP that a discovery process instance is responsible for shall be referred to as the local (T)CP. + +## **10.3 Discovery process instance** + +- R-6 A discovery process instance shall identify bidirectional transport entities that are bound to the local (T)CP through one of two processes: configuration by the Management Plane or LAD. +- R-7 The bidirectional transport entity shall be identified by the combination of the local (T)CP, local DA, remote (T)CP and remote DA Identifiers. +- R-8 The discovery process shall be able to identify the capabilities of the remote (T)CP. +- R-9 The discovery process shall be able to retrieve the capabilities of the local (T)CP. +- R-10 The discovery process shall be able to negotiate the capabilities allowed by remote operator policy for the local (T)CP. +- R-11 The discovery process shall be able to negotiate the capabilities allowed by local operator policy for the remote (T)CP. +- R-12 The discovery process shall allow the capabilities negotiated for the remote (T)CP and negotiated for the local (T)CP to be different. + +## **10.4 Discovery of a transport entity** + +- R-13 The LAD process shall support use of one or both of the following in-band channels: trail overhead associated with the local (T)CP (Type 1), or trail payload associated with the local (T)CP (Type 2). +- R-14 It shall be possible for the Management Plane to enable/disable the transmission of the discovery message. +- R-15 The discovery process shall enable the LAD process when the method for identifying a transport entity is set for LAD. +- R-16 The LAD process shall not run when the method to identify the transport entity is set to management configuration. +- R-17 The discovery process shall be able to stop the transmission of the discovery message once the transport entity has been discovered. + +## **10.5 Discovery of a unidirectional transport entity** + +R-18 To facilitate the discovery of a unidirectional transport entity, a discovery process shall periodically send a discovery message on the in-band channel associated with the local (T)CP containing information to uniquely identify the local (T)CP. + +R-19 The LAD process shall identify the remote (T)CP bound to the inbound unidirectional transport entity by listening to the in-band channel associated with the local (T)CP for a discovery message. + +R-20 The local LAD process shall notify the remote LAD process of the inbound unidirectional transport entity identified by sending a discovery acknowledgment containing the received (T)CP ID, received DA ID, and the (T)CP ID and DA ID for the local (T)CP. + +## **10.6 Discovery of a bidirectional transport entity** + +R-21 The LAD process shall identify the bidirectional transport entity by separately identifying the inbound and outbound unidirectional transport entities associated with the local (T)CP. + +R-22 The LAD process shall identify if the two unidirectional transport entities are connected to the same remote (T)CP. + +R-23 The LAD process shall notify the discovery process instance if the two unidirectional transport entities are not connected to the same remote (T)CP. + +## **10.7 Discovery of transport entity capabilities** + +R-24 The TCE process shall support exchanging at a minimum the following type of information: + +- Transport plane capabilities of the end point attached to the transport entity. + +R-25 A common generic process should exist to support all types of transport entity capability information. + +R-26 It shall be possible to add additional TCE information types without complete re-specification of the TCE process. + +R-27 The various types of transport entity capability information related to a trail shall be allowed to have separate, independent TCE sessions. + +R-28 It shall be possible to update the transport entity capability information without taking a link/trail out of service. + +R-29 The TCE process shall count the number of failed capability negotiation attempts and may stop after exceeding a management configurable threshold. + +R-30 The TCE process shall continue to use the already negotiated capabilities if a re-negotiation of new capabilities cannot be accomplished. + +R-31 The consequent actions for a failed TCE re-negotiation attempt shall be defined by Management Plane policy. + +R-32 The TCE process shall only start to use new capabilities after re-negotiation has been completed. + +# **11 Discovery messages** + +The LAD process uses a message-based scheme which exchanges identity attributes. There is no assumption made on whether the same or different protocols are needed for the different instances of discovery. The actual protocol may operate in either an acknowledged or unacknowledged mode. In the acknowledged mode, the discovery message might carry the near-end identity attributes and + +the acknowledgement can carry the far-end identity attributes in response to the received near-end attributes. Additionally, the transport entity capability information may also be carried as part of the acknowledgement. In the unacknowledged mode, each end sends its respective identity attributes, and TCE is done at a different time. In either mode, the messages shall be sent until the discovery process is completed. Clauses 11.1 and 11.2 provide the messages and attributes for an acknowledged discovery process. + +## 11.1 LAD process + +### 11.1.1 LAD-LAD interface + +**Table 11-1/G.7714/Y.1705 – LAD-LAD interface messages** + +| | | +|----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| LADDiscMsg | LAD Message contains:
(T)CP ID for local (T)CP,
DA ID for local (T)CP. | +| LADDiscAckMsg | LAD Ack Message contains:
(T)CP ID for local (T)CP,
(T)CP ID received in the LADDiscMsg,
DA ID for the local (T)CP,
DA ID received in the LADDiscMsg. | + +NOTE – If the (T)CP ID is from a global name space, then the DA-scoped (T)CP ID and the DA ID can be derived, removing the need to pass the DA ID. + +### 11.1.2 DT-LAD interface + +**Table 11-2/G.7714/Y.1705 – DT-LAD interface message** + +| | | +|----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DTLADStart | LAD Start Message contains:
Channel to use for discovery,
Selection of continuous or edge-trigger discovery,
Local-endpoint DA ID and (T)CP ID. | +| DTLADStop | LAD Stop Message: No attributes are required. | +| LADDTMiswire | LAD Miswire Notification Message contains:
Local-endpoint DA ID and (T)CP ID,
Local-endpoint DA ID and (T)CP ID received in DiscAckMsg,
Remote-endpoint DA ID and (T)CP ID received in DiscAckMsg,
Remote-endpoint DA ID and (T)CP ID received in DiscMsg. | +| LADDTLinkDisc | LAD Transport Entity Binding Discovered Message contains:
Local-endpoint DA ID and (T)CP ID,
Remote-endpoint DA ID and (T)CP ID. | +| LADDTLinkLost | LAD Transport Entity Binding Lost Message contains:
Local-endpoint DA ID and (T)CP ID,
Remote-endpoint DA ID and (T)CP ID. | + +## 11.2 TCE process + +The capability attributes exchanged in these messages include: + +- i) The client CI types supported. +- ii) The ability to support flexible adaptation. +- iii) The adaptations supporting the client CI types. +- iv) Attributes used by specific applications (e.g., routing, signalling, management applications). + +NOTE – The A-end only sends A-end TCE attributes to the Z-end and vice versa. Moreover, the TCE attributes are exchanged on a per-layer basis and the set of TCE attributes defined above is exchanged for each layer (e.g., RS, MS, VC-4, VC-4-nc, VC-12). + +### 11.2.1 TCE-TCE interface + +**Table 11-3/G.7714/Y.1705 – TCE-TCE interface messages** + +| | | +|-------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------| +| TCECapReq | TCE Capability Request Message contains:
Local-endpoint DA ID and (T)CP ID,
Remote-endpoint DA ID and (T)CP ID,
Local-endpoint offered capability. | +| TCECapAck | TCE Capability Ack Message contains:
Local-endpoint DA ID and (T)CP ID,
Remote-endpoint DA ID and (T)CP ID. | +| TCECapNack | TCE Capability Nack Message contains:
Local-endpoint DA ID and (T)CP ID,
Remote-endpoint DA ID and (T)CP ID,
Refused capability or capability setting. | + +### 11.2.2 DT-TCE interface + +**Table 11-4/G.7714/Y.1705 – DT-TCE interface messages** + +| | | +|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DTTCEStart | TCE Negotiation Start Message contains:
Local DA ID and (T)CP ID,
Remote DA ID and (T)CP ID,
Capability of local endpoint,
Negotiation Policy for local endpoint,
Negotiation Policy for remote endpoint. | +| DTTCEStop | TCE Stop Message: No attributes are required. | +| TCEDTCapCom | TCE Negotiation Complete contains:
Capability negotiated for local endpoint,
Capability negotiated for remote endpoint. | + +# 12 Discovery state machine descriptions + +The state machines of the discovery process presented in clause 6 are described in the following subclauses. + +## 12.1 LAD state machine + +The LAD sub-process shown in Figure 6-1 is elaborated in a state diagram that is depicted in Figure I.1. The state descriptions, event descriptions and state transitions are shown in Tables 12-1 to 12-6. + +Within Figure I.1, the LAD sub-process is broken down into two independent state machines. Both state machines need to be run at each end of the transport entity (e.g., trail or link) in order for its end points to be discovered. If one end is not running the LAD process, the end points of the transport entity will not be discovered. + +The LAD Tx state machine handles the periodic transmission of discovery messages. The LAD state machine handles the receipt of discovery messages as well as generation of discovery acknowledgments. + +The discovery messages being exchanged identify the unidirectional links that make up a bidirectional link. Once both unidirectional links have been identified and validated for miswiring, a notification will be provided to the DT process identifying the end points discovered. If miswiring is identified or a change in the end points is identified, the DT process will be notified. + +When the LAD state machine instance is created, the state machine enters State 1 ( $S_{IDLE}$ ) and the LAD Tx state machine instance is created. The LAD state machine will transition through the left or right branches of the LAD state machine depending on the time sequence of the received discovery messages. Once the LAD state machine identifies the end points of the link, it enters State 4 ( $S_{A-Z-Z-UNKNOWN}$ ). When transitioning to State 4 of the LAD state machine, the LAD Tx State Machine may be stopped. + +Note that the state machine runs at one end of the transport entity, and an identical machine runs at the other end. The left and right branches off the State 1 ( $S_{IDLE}$ ) do not depict this end and the far end, but specify the behaviour when the Discovery message (from the far end) is received before or after the DiscAck message for the local DiscMsg. Every time the State 1 ( $S_{IDLE}$ ) is entered it is ensured that the LAD Tx state machine is running. + +If the connection is found to be miswired, the state machine remains in states 2 or 3 and a notification is sent to the DT process. + +The NULL state is before the LAD state machine is created. + +**Table 12-1/G.7714/Y.1705 – LAD events** + +| | | +|---------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| StartLADInstance | This event occurs when the LAD Instance is created by the DT process. | +| RxDiscMsgMatchedZ | This event occurs when a Discovery Message is received, and the Z-end point identifier contained matches the Z identifier previously observed. | +| RxDiscMsgUnMatchedZ | This event occurs when a Discovery Message is received, and the Z-end point identifier contained does not match the Z-end point identifier previously observed. | +| RxDiscAckMatchedZ | This event occurs when a Discovery Ack Message is received, and the Z-end point identifier contained matches the Z-end point identifier previously observed. | +| RxDiscAckUnMatchedZ | This event occurs when a Discovery Ack Message is received, and the Z-end point identifier contained does not match the Z-end point identifier previously observed. | +| FAIL | This event occurs when the connectivity supervision lost indication occurs for the (T)CP. | +| StopLADInstance | This event occurs when the LAD Instance is destroyed by the DT process. | + +**Table 12-2/G.7714/Y.1705 – LAD actions** + +| | | +|--------------------------|-------------------------------------------------------------------------------------| +| StartLADTxInstance | This action creates a LADTx Instance operating on the local (T)CP. | +| TerminateLADTxInstance | This action destroys a LAD Tx Instance operating on the local (T)CP. | +| SetObservedZIdentifier | This action records the Z-end point identifier received in a DiscMsg or DiscAckMsg. | +| UnsetObservedZIdentifier | This action invalidates the Z-end point identifier previously observed. | +| NotifyDTMiswire | This action sends a LADDTMiswire message to DT. | +| NotifyDTLinkFound | This action sends a LADDTLinkDisc message to DT. | +| NotifyDTLinkLost | This action sends a LADDTLinkLost message to DT. | +| TxDiscAck | This action sends a LADDiscAckMsg to the remote LAD instance. | + +**Table 12-3/G.7714/Y.1705 – LADTx events** + +| | | +|--------------------|----------------------------------------------------------------------------| +| StartLADTxInstance | This event occurs when the LADTx Instance is created by the LAD process. | +| Timeout | This event occurs when the transmission timer expires. | +| StopLADInstance | This event occurs when the LADTx Instance is destroyed by the LAD process. | + +**Table 12-4/G.7714/Y.1705 – LADTx Actions** + +| | | +|------------------|-------------------------------------------------------------------------------------------------| +| StartTxTimer | This action sets the transmission timer and starts the timer. | +| RestartTxTimer | This action resets the transmission timer and starts the timer. | +| TerminateTxTimer | This action stops the transmission timer. No expiration can occur until the timer is restarted. | +| TxDiscMsg | This action sends a LADDiscMsg on the local (T)CP to the remote LAD process. | + +**Table 12-5/G.7714/Y.1705 – LAD state machine** + +| Events | Actions | +|---------------------|----------------------------------------------------------------| +| StartLADInstance | slt = StartLADTxInstance
tlr = TerminateLADTxInstance | +| RxDiscMsgMatchedZ | | +| RxDiscMsgUnMatchedZ | uoz = UnsetObservedZIdentifier
soz = SetObservedZIdentifier | +| RxDiscAckMatchedZ | | +| RxDiscAckUnMatchedZ | ndm = NotifyDTMiswire
nlf = NotifyDTLinkFound | +| FAIL | nll = NotifyDTLinkLost | +| StopLADInstance | tda = TxDiscAck | + +| States | 0 | 1 | 2 | 3 | 4 | +|---------------------|-----------|-------------------|--------------------------|-----------------------|---------------------------| +| Events | NULL | S IDLE | S A-ZKnown | S Z-AKnown | S A-Z-Z-AKnown | +| StartLADInstance | 1 slt,uoz | – | – | – | – | +| RxDiscAckMatchedZ | – | 2 soz | 2 soz | 4 tlt (Note),nlf | 4 | +| RxDiscAckUnMatchedZ | – | 2 soz | 2 soz | 3 ndm | 1 slt,uoz,nll | +| RxDiscMsgMatchedZ | – | 3 soz,tda | 4 tlt (Note),
nlf,tda | 3 soz,tda | 4 tda | +| RxDiscMsgUnMatchedZ | – | 3 soz,tda | 2 ndm,tda | 3 soz,tda | 3
slt,soz,nll,tda | +| FAIL | – | 1 | 1 uoz | 1 uoz | 1 slt,uoz,nll | +| StopLADInstance | – | 0 tlt (Note) | 0 tlt (Note) | 0 tlt (Note) | 0 | + +NOTE – The LAD Tx Instance may be stopped when transitioning to State 4, allowing the in-band channel to be used by other applications. Transitions out of State 4 to other states requires restarting the LADTxInstance. If the LADTxInstance is not stopped when transitioning to State 4, then it must be stopped when a StopLADInstance event occurs in State 4. + +**Table 12-6/G.7714/Y.1705 – LAD Tx state machine** + +| Events | Actions | | +|--------------------|------------------------------------------------|--| +| StartLADTxInstance | stt = StartTxTimer | | +| StopLADTxInstance | rtt = RestartTxTimer
ttt = TerminateTxTimer | | +| Timeout | tdm = TxDiscMsg | | + + + +| | | | | +|-------------------|--------|-----------|-------------------| +| | States | 0 | 1 | +| Events | | NULL | S IDLE | +| StartLADInstance | | 1 stt,tdm | – | +| Timeout | | – | 1 rtt,tdm | +| StopLADTxInstance | | – | 0 ttt | + +## 12.2 TCE state machine + +The state table shown in Table 12-9 defines the state machine for the TCE process. A separate instance of the TCE state machine is created for each (T)CP for which discovery is enabled. Therefore, for any transport entity discovered by LAD, a separate instance of the TCE state machine will exist for each end of the transport entity. These instances will communicate with each other using the messages defined in Table 11-2 as well as their respective Discovery Trigger (DT) processes. As messages are received, they cause the events shown in Table 12-7. These events in turn cause state transitions and/or the actions defined in Table 12-83. + +The state machine starts in State 2 when created. The Discover Trigger process will start the TCE process with a DTTCEStart message, causing the TCE process to initialize the retransmission timer and send a TCECapReq message to the remote TCE process. As TCECapReq or TCECapAck messages are received from the remote TCE process, the state machine will transition to either state 7 or 8, depending on the order the messages are received. If TCECapReq messages are received containing capabilities that are supported, a TCECapAck message will be sent, otherwise a TCECapNak will be sent containing the capability that is not supported/allowed by the local (T)CP. If an excessive number of renegotiations occur (as defined by management), then the state machine will stop, and enter State 3. It will only be restarted if the DT Process terminates and restarts TCE. + +When both sides have successfully negotiated capabilities information, the state machine will transition to State 9. It is possible to negotiate a change in capabilities while in State 9 by sending a TCECapReq message to the far TCE process containing the set of capabilities already negotiated and the requested new capabilities. If the far TCE process will support/allow the capabilities in the TCECapReq message, then a TCECapAck will be returned. If not supported/allowed, then a TCECapNak will be returned. + +If the DT process wishes to stop the TCE process, it will send a DTTCEStop message to the TCE instance. If the DT process is in States 6, 7, 8, 9 or 10, it will attempt to gracefully stop the TCE process by sending a TCETermReq message. This will be retransmitted until either a TCETermAck message is received, or the retransmission count is exceeded. + +3 The specific transitions and actions are found by locating the intersection of current state of the state machine and the event received in the state table. The numeric value indicates the resulting state, while the mnemonics indicate the actions to perform. + +The TCE state machine is shown in Figure I.2. The state descriptions, event descriptions and state transitions are shown in Tables 12-7 to 12-9. + +**Table 12-7/G.7714/Y.1705 – TCE events** + +| | | +|-----------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------| +| StartTCE | This event occurs when the TCE instance receives a DTTCEStart message. | +| TerminateTCE | This event occurs when the TCE instance receives a DTTCEStop message. | +| Change Capabilities | This event occurs when the capabilities of the local (T)CP is changed. | +| Timeout with counter >0 | This event occurs when the transmission timer expires, and the transmission counter is not less than zero. | +| Timeout with counter expired | This event occurs when the transmission timer expires, and the transmission counter is 0. | +| Receive-Capability-Request (Good) | This event occurs when a TCECapReqMsg is received, and the capabilities included are acceptable given the local policy for the (T)CP. | +| Receive-Capability-Request (Bad) | This event occurs when a TCECapReqMsg is received, and the capabilities included are not acceptable given the local policy for the (T)CP. | +| Receive-Capability-Ack | This event occurs when a TCECapAckMsg is received indicating that the capabilities previously sent are acceptable to the remote discovery TCE instance. | +| Receive-Capability-Nak/Rej | This event occurs when a TCECapNakMsg is received indicating that the capabilities previously sent are not acceptable to the remote discovery TCE instance. | +| Receive-Terminate-Request | This event occurs when a TCETermReq is received indicating that the remote discovery TCE instance is going out-of-service. | +| Receive-Terminate-Ack | This event occurs when a TCETermAck is received indicating that the remote discovery TCE instance has received the locally generated TCETermReq. | + +**Table 12-8/G.7714/Y.1705 – TCE actions** + +| | | +|--------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NotifyDTCapNegComplete | This action sends a TCEDTCapCom message to the DT | +| NotifyDTCapNegLost | This action sends a TCEDTCapLost message to the DT indicating that TCE Negotiation has been terminated at the request of the remote TCE instance. | +| Initialize-Restart-Count | This action resets the retransmission counter to a maximum number of retransmission attempts specified by the management plane. | +| Zero-Restart-Count | This action sets the transmission counter to zero. | +| Send-Capability-Request | This action sends a TCECapReq message to the remote TCE, and decrements the retransmission counter. | +| Send-Capability-Ack | This action sends a TCECapAck message to the remote TCE. It does not decrement the retransmission timer. | +| Send-Capability-Nack/Rej | This action sends a TCECapNack message to the remote TCE. It does not decrement the retransmission timer. | +| Send-Terminate-Request | This action sends a TCETermReq message to the remote TCE notifying it that Capabilities Exchange is being stopped. It decrements the retransmission counter. | +| Send-Terminate-Ack | This action sends a TCETermAck message to the remote TCE acknowledging a received TCETermReq message. It does not decrement the retransmission counter. | + +**Table 12-9/G.7714/Y.1705 – TCE state machine** + +| Events | Actions | +|------------------------------------------|--------------------------------| +| STCE = Start TCE | tlu = NotifyDTPCapNegComplete | +| TTCE = Terminate TCE | tld = NotifyDTPCapNegLost | +| CC = ChangeCapabilities | | +| TO+ = Timeout with counter > 0 | irc = Initialize-Restart-Count | +| TO- = Timeout with counter expired | zrc = Zero-Restart-Count | +| RCR+ = Receive-Capability-Request (Good) | scr = Send-Capability-Request | +| RCR- = Receive-Capability-Request (Bad) | | +| RCA = Receive-Capability-Ack | sca = Send-Capability-Ack | +| RCN = Receive-Capability-Nak/Rej | scn = Send-Capability-Nak/Rej | +| RTR = Receive-Terminate-Request | str = Send-Terminate-Request | +| RTA = Receive-Terminate-Ack | sta = Send-Terminate-Ack | + +| States | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | +|--------|--------------------|------------------|---------|----------|-----------------|-------------------|-------------------|------------------|--------------------| +| Events | A-Z/Z-A
Unknown | Stopped | Closing | Stopping | CapReq-
Sent | A-ZOK,
Z-AUnkn | Z-AOK,
A-ZUnkn | A-ZOK,
Z-AOK | Z-AOK,
A-ZReneg | +| STCE | 6 irc,scr | 3 | 5 | 5 | 6 | 7 | 8 | 9 | 10 | +| TTCE | 2 | 2 | 4 | 4 | 4 irc,str | 4 irc,str | 4 irc,str | 4 tld,irc,str | 4 tld,irc,str | +| CC | 2 | 3 | 4 | 5 | 6 scr | 6 scr | 8 scr | 10 scr | 10 scr | +| TO+ | – | – | 4 str | 5 str | 6 scr | 6 scr | 8 scr | – | 10 scr | +| TO– | – | – | 2 | 3 | 3 | 3 | 3 | – | 9 | +| RCR+ | 2 sta | 8
irc,scr,sca | 4 | 5 | 8 sca | 9 sca,tlu | 8 sca | 9 tlu,sca | 10 sca | +| RCR– | 2 sta | 6
irc,scr,scn | 4 | 5 | 6 scn | 7 scn | 6 scn | 9 scn | 10 scn | +| RCA | 2 sta | 3 sta | 4 | 5 | 7 irc | 6 scr | 9 irc,tlu | 6 tld,scr | 9 tlu | +| RCN | 2 sta | 3 sta | 4 | 5 | 6 irc,scr | 6 scr | 8 irc,scr | 6 tld,scr | 10 scr | +| RTR | 2 sta | 3 sta | 4 sta | 5 sta | 6 sta | 6 sta | 6 sta | 5
tld,zrc,sta | 5
tld,zrc,sta | +| RTA | 2 | 3 | 2 | 3 | 6 | 6 | 8 | 6 tld,scr | 6 tld,scr | + +# Appendix I + +## Discovery process state machines + +![LAD state machine diagram showing four states (1-4) and transitions between them. Includes an inset for the LAD Tx State Machine.](552265bdbcf6d43d341fd018a9076269_img.jpg) + +The diagram illustrates the LAD state machine and the LAD Tx State Machine. + +**LAD state machine** + +The main state machine has four states: 1 (SIDLE), 2 (SA-ZKnown), 3 (SZ-AKnown), and 4 (SA-Z-Z-AKnown). + +- State 1 (SIDLE):** Initial state. Transitions to State 2 on "RxDiscAckMatchedZ, RxDiscAckUnmatchedZ/ SetObservedZIdentifier". Transitions to State 3 on "RxDiscMsgMatchedZ, RxDiscMsgUnmatchedZ/ TxDiscAck, SetObservedZIdentifier". Transitions to State 4 on "FAIL/ UnsetObservedZIdentifier". Self-loops on "FAIL". External transitions: "StartLADInstance/ StartLADTxInstance" (entry), "StopLADInstance/ StopLADTxInstance" (exit). +- State 2 (SA-ZKnown):** Transitions to State 1 on "UnsetObservedZIdentifier". Transitions to State 3 on "RxDiscMsgUnMatchedZ/ TxDiscAck, NotifyDTMiswire". Transitions to State 4 on "RxDiscMsgMatchedZ/ TxDiscAck, StopLADTxInstance\*, NotifyDALink". Self-loops on "RxDiscAckMatchedZ, RxDiscAckUnmatchedZ/ SetObservedZIdentifier" and "RxDiscMsgUnMatchedZ/ TxDiscAck, NotifyDTMiswire". External transition: "StopLADInstance/ StopLADTxInstance" (exit). +- State 3 (SZ-AKnown):** Transitions to State 1 on "UnsetObservedZIdentifier". Transitions to State 2 on "RxDiscMsgUnMatchedZ/ TxDiscAck, NotifyDTMiswire". Transitions to State 4 on "RxDiscMsgUnMatchedZ/ TxDiscAck, SetObservedZIdentifier/ StartLADTxInstance\*, NotifyDALinkDown". Self-loops on "RxDiscMsgMatchedZ, RxDiscMsgUnmatchedZ/ TxDiscAck, SetObservedZIdentifier" and "RxDiscAckUnmatchedZ/ NotifyDTMiswire". External transition: "StopLADInstance/ StopLADTxInstance" (exit). +- State 4 (SA-Z-Z-AKnown):** Transitions to State 1 on "FAIL/ UnsetObservedZIdentifier". Transitions to State 2 on "RxDiscAckUnmatchedZ/ StartLADTxInstance\*, UnsetObservedZIdentifier, NotifyDALinkDown". Transitions to State 3 on "RxDiscAckMatchedZ/ StopLADTxInstance\*, NotifyDALink". Self-loops on "RxDiscAckMatchedZ" and "RxDiscMsgMatchedZ/ TxDiscAck". External transition: "StopLADInstance/ StopLADTxInstance\*" (exit). + +**LAD Tx State Machine** + +The LAD Tx State Machine has one state: 1 (SIDLE). + +- State 1 (SIDLE):** Transitions to itself on "StartLADTxInstance/ StartTimer, TxDiscMsg" and "Timeout/ RestartTimer, TxDiscMsg". External transition: "StopLADTxInstance" (exit). + +**\* NOTE –** The LAD Tx Instance may be stopped when transitioning to State 4, allowing the in-band channel to be used by other applications. Transitions from State 4 to other states requires restarting the LADTxInstance. If the LADTxInstance is not stopped when entering State 4, it must be stopped when a StopLADInstance event occurs in State 4. + +LAD state machine diagram showing four states (1-4) and transitions between them. Includes an inset for the LAD Tx State Machine. + +G.7714/Y.1705\_FI-1 + +Figure I.1/G.7714/Y.1705 – LAD state Machine + +![State machine diagram for TCE (Figure I.2/G.7714/Y.1705). The diagram shows 10 states (1-10) and their transitions based on various triggers and actions. States include S_A-Z-Z-A Unknown, S_STOPPED, S_CAPREQ-SENT, S_A-ZOK-Z-AUNKN, S_CLOSING, S_Z-AOK-Z-AUNKN, S_Z-AOK-A-ZRENEG, S_A-ZOK-Z-AOK, S_STOPPING, and S_A-ZOK-A-ZRENEG. Transitions are labeled with conditions and actions like TTCE, CC, RTA, STCE, RCR, RCA, RCN, RTR, TO, etc.](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg) + +The diagram illustrates the TCE state machine with 10 states and their transitions: + +- State 1:** $S_{A-Z-Z-A\ Unknown}$ . Initial state via CREATE/. Transitions: to 2 (STCE/irc,scr), to 3 (STCE,CC,RTA/scr), to 6 (RCA/irc), to 7 (TO-/scr), to 8 (RCR-/irc,scr,scn), to 9 (RCR-/irc,scr,scn), to 10 (RCR-/irc,scr,scn). +- State 2:** $S_{A-Z-Z-A\ Unknown}$ . Self-loops: TTCE,CC,RTA/ (no action), RCR+,RCR-,RCA,RCN/ (no action), RTR/ (no action). +- State 3:** $S_{STOPPED}$ . Self-loops: STCE,CC,RTA/scr (no action), TTCE/ (no action), RCA,RCN,RTR/scr (no action). +- State 4:** $S_{CLOSING}$ . Transitions: to 2 (STCE,CC,RTA/scr), to 3 (TO-/scr), to 6 (RCR-/irc,scr,scn), to 7 (TO-/scr), to 8 (RCR-/irc,scr,scn), to 9 (RCR-/irc,scr,scn), to 10 (RCR-/irc,scr,scn). +- State 5:** $S_{STOPPING}$ . Self-loops: TO-/RTA/ (no action), STCE,CC,RCR+,RCR-,RCA,RCN/ (no action), TO+/str (no action), RTR/ (no action). +- State 6:** $S_{CAPREQ-SENT}$ . Transitions: to 2 (STCE,CC,RTA/scr), to 3 (TO-/scr), to 4 (RCR-/irc,scr,scn), to 7 (TO-/scr), to 8 (RCR-/irc,scr,scn), to 9 (RCR-/irc,scr,scn), to 10 (RCR-/irc,scr,scn). +- State 7:** $S_{A-ZOK-Z-AUNKN}$ . Transitions: to 2 (STCE,CC,RTA/scr), to 3 (TO-/scr), to 4 (RCR-/irc,scr,scn), to 6 (RCR-/irc,scr,scn), to 8 (RCR-/irc,scr,scn), to 9 (RCR-/irc,scr,scn), to 10 (RCR-/irc,scr,scn). +- State 8:** $S_{Z-AOK-Z-AUNKN}$ . Transitions: to 2 (STCE,CC,RTA/scr), to 3 (TO-/scr), to 4 (RCR-/irc,scr,scn), to 6 (RCR-/irc,scr,scn), to 7 (RCR-/irc,scr,scn), to 9 (RCR-/irc,scr,scn), to 10 (RCR-/irc,scr,scn). +- State 9:** $S_{A-ZOK-Z-AOK}$ . Transitions: to 2 (STCE,CC,RTA/scr), to 3 (TO-/scr), to 4 (RCR-/irc,scr,scn), to 6 (RCR-/irc,scr,scn), to 7 (RCR-/irc,scr,scn), to 8 (RCR-/irc,scr,scn), to 10 (RCR-/irc,scr,scn). +- State 10:** $S_{Z-AOK-A-ZRENEG}$ . Transitions: to 2 (STCE,CC,RTA/scr), to 3 (TO-/scr), to 4 (RCR-/irc,scr,scn), to 6 (RCR-/irc,scr,scn), to 7 (RCR-/irc,scr,scn), to 8 (RCR-/irc,scr,scn), to 9 (RCR-/irc,scr,scn). + +State machine diagram for TCE (Figure I.2/G.7714/Y.1705). The diagram shows 10 states (1-10) and their transitions based on various triggers and actions. States include S\_A-Z-Z-A Unknown, S\_STOPPED, S\_CAPREQ-SENT, S\_A-ZOK-Z-AUNKN, S\_CLOSING, S\_Z-AOK-Z-AUNKN, S\_Z-AOK-A-ZRENEG, S\_A-ZOK-Z-AOK, S\_STOPPING, and S\_A-ZOK-A-ZRENEG. Transitions are labeled with conditions and actions like TTCE, CC, RTA, STCE, RCR, RCA, RCN, RTR, TO, etc. + +G.7714/Y.1705\_FI-2 + +**Figure I.2/G.7714/Y.1705 – TCE state machine** + +NOTE – The numbering of the states in this figure is consistent with the description contained in Appendix II. + +## Appendix II + +### Mapping of TCE state machine to RFC 1661 LCP state machine + +The TCE state machine defined in this Recommendation is derived from the Link Control Protocol (LCP) state machine defined in IETF RFC 1661, "Point-to-Point Protocol". This state machine is used by PPP to negotiate the configuration details, including the capabilities of an endpoint, for packet layer protocols operating over a point-to-point connection. This state machine has been widely deployed in systems using many different interoperable implementations. The modifications from the LCP state machine are described in this Appendix. + +### Removal of operational state change-events + +The TCE process is initiated by the Discovery Trigger process. This process already handles the transitions related to Administrative State (OPEN and CLOSE) and Operational State (UP and DOWN), making the handling of Operational State change-events in the TCE state machine unnecessary. With the removal of UP and DOWN events, the state machine now starts in *State 2: Closed*, instead of *State 0: Initial*. Furthermore *State 1: Starting*, previously used to handle the transition to Administrative Enabled while Operationally Out-of-Service, is also no longer necessary. + +### Addition of change capabilities negotiation + +Requirement R-28 states that it must be possible to change the capabilities information for an endpoint and notify the endpoint bound to the other end of the transport entity without taking the transport entity out of service. However, LCP does not allow for configuration information to change without taking the connection out of service. To handle this, the *Receive Cap Req (RCR)* event is now processed in *State 9: A-ZOK, Z-AOK* instead of transitioning to *State 6: CapReqSent* or *State 8: Z-AOK, A-ZUNKN*. Additionally, a new event *ChangeCap* and a new state *State 10: Renegotiation* has been added to handle the reception of a *ChangeCap* event while in *State 9: A-ZOK, Z-AOK*. + +### Change of state names + +The state names for LCP focus on the events that have occurred in the past without describing the amount of information known. The TCE state names focus on the information known as each state is achieved. To assist those familiar with LCP states, the mapping between LCP states and TCE states is shown in Table II.1. + +**Table II.1/G.7714/Y.1705 – Mapping of LCP states to TCE states** + +| RFC 1661 LCP State Name | G.7714/Y.1705 TCE State Name | +|--------------------------------|-------------------------------------| +| State 0: Initial | – | +| State 1: Starting | – | +| State 2: Closed | State 2: A-Z, Z-A Unknown | +| State 3: Stopped | State 3: Stopped | +| State 4: Closing | State 4: Closing | +| State 5: Stopping | State 5: Stopping | +| State 6: ConfReq Sent | State 6: CapReq Sent | +| State 7: Ack-Recvd | State 7: A-Z OK, Z-A Unkn | +| State 8: Ack-Sent | State 8: Z-A OK, A-Z Unkn | +| State 9: Opened | State 9: A-Z OK, Z-A OK | +| – | State 10: Z-A OK, A-Z Reneg | + +## **Appendix III** + +## **Rationale for removal of CELA process** + +The 2001 version of ITU-T Rec. G.7714/Y.1705 included discussion of Control Entity Logical Adjacency, or CELA. This was previously defined as the association that existed between two discovery processes to facilitate communication between a pair of control entities across the SCN. The term CELA was utilized prior to the development of the G.8080 discovery architecture, and prior to consideration that the Management Plane could benefit from the automatic discovery process. + +This version of ITU-T Rec. G.7714/Y.1705 allows the discovery process to be used by the Management Plane as well as the Control Plane, making the term CELA inappropriate. As the G.8080 architectural construct is the DA (Discovery Agent), the appropriate term to substitute for CELA would be Discovery Agent adjacency. However, after further inspection, it was determined that the adjacency did not need to be pre-established; it could be created dynamically while other parts of the discovery process (i.e., LAD and TCE) were being executed. Furthermore, it was determined that the communications that occurred across the adjacency were not scoped by the adjacency, removing the distinction from the messaging services provided by the DCN. + +Consequently, discussion of the Discovery Agent adjacency is not included in this Recommendation. + +## ITU-T Y-SERIES RECOMMENDATIONS + +## GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS + +### GLOBAL INFORMATION INFRASTRUCTURE + +| | | +|-------------------------------------------|-------------| +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | + +### INTERNET PROTOCOL ASPECTS + +| | | +|--------------------------------------------------------------------|----------------------| +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | + +### NEXT GENERATION NETWORKS + +| | | +|-------------------------------------------------------------------|---------------| +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Numbering, naming and addressing | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Network control architectures and protocols | Y.2500–Y.2599 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.7714.1-201708-I_PDF-E/raw.md b/marked/G/T-REC-G.7714.1-201708-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..99ebdfdb370c3dc43ba1c6c2ac6e8206e2bd98dd --- /dev/null +++ b/marked/G/T-REC-G.7714.1-201708-I_PDF-E/raw.md @@ -0,0 +1,1321 @@ + + +**ITU-T** + +**G.771.1/Y.1705.1** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(08/2017) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Data over Transport – Generic aspects – Transport +network control aspects + +SERIES Y: GLOBAL INFORMATION +INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, +NEXT-GENERATION NETWORKS, INTERNET OF +THINGS AND SMART CITIES + +Internet protocol aspects – Operation, administration and +maintenance + +# --- **Protocol for automatic discovery in transport networks** + +Recommendation ITU-T G.771.1/Y.1705.1 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| General | G.7000–G.7099 | +| Transport network control aspects | G.7700–G.7799 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.7714.1/Y.1705.1 + +# Protocol for automatic discovery in transport networks + +## Summary + +Recommendation ITU-T G.7714.1/Y.1705.1 describes the methods, procedures and transport plane mechanisms for discovering layer adjacency according to the requirements of Recommendation ITU-T G.7714/Y.1705. Layer adjacency discovery describes the process of discovering link connection end-point relationships and verifying their connectivity. Two alternative methods are described: one using a test set in the client layer, the other using in-band overhead in the server layer. Additional actions that may be required for obtaining physical media adjacency discovery, transport entity capability exchange, etc., will be addressed in future Recommendations. + +Recommendation ITU-T G.7714.1/Y.1705.1 (2017) includes: + +- 1) support for transport networks other than synchronous digital hierarchy (SDH) and optical transport network (OTN), specifically Ethernet (ETH); and +- 2) errata updates. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|---------------------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.7714.1/Y.1705.1 | 2003-04-22 | 15 | 11.1002/1000/6291 | +| 1.1 | ITU-T G.7714.1/Y.1705.1 (2003) Amd. 1 | 2006-02-17 | 15 | 11.1002/1000/8748 | +| 2.0 | ITU-T G.7714.1/Y.1705.1 | 2010-09-06 | 15 | 11.1002/1000/10896 | +| 3.0 | ITU-T G.7714.1/Y.1705.1 | 2015-01-13 | 15 | 11.1002/1000/12379 | +| 4.0 | ITU-T G.7714.1/Y.1705.1 | 2017-08-13 | 15 | 11.1002/1000/13337 | + +## Keywords + +Auto-discovery, automatic switched optical network, automatic switched transport network, layer adjacency discovery, network resources. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2017 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | | Page | +|--------------|------------------------------------------------------------------------------------------------------------------|------| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Discovery methodology..... | 4 | +| 5.1 | CP-CP connectivity relationships determination..... | 5 | +| 6 | Mechanisms for layer adjacency discovery ..... | 5 | +| 6.1 | Layer adjacency discovery of transport entities ..... | 5 | +| 7 | Attributes used in layer adjacency ..... | 6 | +| 8 | Layer adjacency based on trail trace string..... | 7 | +| 8.1 | Discovery message formats ..... | 9 | +| 9 | Layer adjacency based on embedded control channel messages..... | 11 | +| 9.1 | LAPD-based mechanism ..... | 12 | +| 9.2 | PPP-based mechanism..... | 12 | +| 9.3 | Interoperable solution when using ECC based mechanism ..... | 12 | +| 9.4 | PPP-based support in OTN ECC..... | 13 | +| 10 | Layer adjacency based on packet OAM frames ..... | 14 | +| 10.1 | Ethernet link discovery mechanism..... | 14 | +| 10.2 | MPLS-TP transport entity discovery mechanism..... | 14 | +| 11 | Procedures..... | 15 | +| 12 | Discovery response message ..... | 15 | +| 12.1 | Miswiring detection..... | 16 | +| 12.2 | Misconnection detection..... | 16 | +| Appendix I | – Implementation example of discovery process..... | 17 | +| I.1 | Layer adjacency discovery information flow ..... | 17 | +| Appendix II | – Miswiring detection..... | 19 | +| II.1 | Auto-discovery procedures..... | 19 | +| II.2 | Example: Interaction between two DAs using different DM formats..... | 23 | +| Appendix III | – Example of discovery response message using a generalized multi-protocol label signalling-based mechanism..... | 25 | +| Appendix IV | – Layer adjacency discovery implementation examples..... | 27 | +| Appendix V | – In-band message encoding example..... | 28 | +| Appendix VI | – Usage of the different discovery mechanisms ..... | 30 | +| VI.1 | Introduction ..... | 30 | +| VI.2 | Categories of Type 1 layer adjacency discovery use cases ..... | 30 | + +| | Page | +|-----------------------------------------------------|-------------| +| VI.3 Use cases and scenarios ..... | 30 | +| VI.4 Guidelines for mechanisms and procedures ..... | 33 | +| Bibliography..... | 37 | + +## Recommendation ITU-T G.7714.1/Y.1705.1 + +# Protocol for automatic discovery in transport networks + +# 1 Scope + +This Recommendation describes the methods, procedures and transport plane mechanisms for discovering layer adjacency according to the requirements of [ITU-T G.7714]. Layer adjacency discovery (LAD) describes the process of discovering link connection (LC) end-point relationships and verifying their connectivity. The term "discovery" is used throughout the Recommendation to refer to both "discovery" and verification. Two alternative methods are described: one using a test set in the client layer; the other using in-band overhead in the server layer. Additional actions that may be required to obtain physical media adjacency discovery, transport entity capability exchange, etc., will be addressed in future Recommendations. + +Equipment developed prior to this Recommendation might not interwork with some of the features developed within this Recommendation. Care should be taken where old and new equipment are to interwork. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016) *Interfaces for the optical transport network.* +- [ITU-T G.805] Recommendation ITU-T G.805 (2000), *Generic functional architecture of transport networks.* +- [ITU-T G.831] Recommendation ITU-T G.831 (2000), *Management capabilities of transport networks based on the synchronous digital hierarchy (SDH).* +- [ITU-T G.7701] Recommendation ITU-T G.7701 (2016), *Common control aspects.* +- [ITU-T G.7712] Recommendation ITU-T G.7712/Y.1703 (2010), *Architecture and specification of data communication network.* +- [ITU-T G.7714] Recommendation ITU-T G.7714/Y.1705 (2005), *Generalized automatic discovery for transport entities.* +- [ITU-T G.8010] Recommendation ITU-T G.8010/Y.1306 (2004), *Architecture of Ethernet layer networks.* +- [ITU-T T.50] Recommendation ITU-T T.50 (1992), *International Reference Alphabet (IRA) (Formerly International Alphabet No. 5 or IA5) – Information technology – 7-bit coded character set for information interchange.* +- [IEEE 802.1AB] IEEE Std 802.1AB-2016, *IEEE Standard for local and metropolitan area networks – Station and media access control connectivity discovery.* +- [IEEE 802.3] IEEE Std 802.3-2015, *Standard for Ethernet.* +- [IETF RFC 1570] IETF RFC 1570 (1994), *PPP LCP extensions.* + +| | | +|-----------------|---------------------------------------------------------------------------------------------------------------------------| +| [IETF RFC 1662] | IETF RFC 1662 (1994), PPP in HDLC-like framing . | +| [IETF RFC 2045] | IETF RFC 2045 (1996), Multipurpose internet mail extensions (MIME) – Part One: Format of Internet message bodies . | +| [IETF RFC 3518] | IETF RFC 3518 (2003), Point-to-point protocol (PPP) bridging control protocol (BCP) . | + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +#### 3.1.1 [ITU-T G.805]: + +- a) adaptation +- b) link +- c) link connection +- d) trail + +#### 3.1.2 [ITU-T G.7701]: + +- a) discovery agent +- b) policy +- c) termination adaptation performer (TAP) + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 local TCP-ID:** A termination connection point identifier (TCP-ID) that has local significance to the discovery agent transmitting the discovery messages. + +**3.2.2 local CP-ID:** A connection point identifier (CP-ID) that has local significance to the discovery agent transmitting the discovery messages. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|-------------------------------------------| +| ADM | Add-Drop Multiplexer | +| AIS | Alarm Indication Signal | +| AITs | Acknowledged Information Transfer Service | +| API | Access Point Identifier | +| ASON | Automatically Switched Optical Network | +| BCP | Bridging Control Protocol | +| CO | Central Office | +| CP | Connection Point | +| CP-ID | Connection Point Identifier | +| DA-ID | Discovery Agent Identifier | +| DA | Discovery Agent | + +| | | +|-------|----------------------------------------------------------| +| DA ID | Discovery Agent Identifier | +| DAPI | Destination Access Point Identifier | +| DCC | Data Communications Channel | +| DCN | Data Communications Network | +| DM | Discovery Message | +| DXC | Digital cross Connect | +| ECC | Embedded Communication Channel | +| ETH | Ethernet | +| ETY | Ethernet PHY | +| GCC | General Communications Channel | +| GMPLS | Generalized Multi-Protocol Label Signalling | +| HDLC | High-level Data Link Control | +| HOVC | Higher Order Virtual Container | +| IP | Internet Protocol | +| IRV | International Reference Version | +| LAD | Layer Adjacency Discovery | +| LAPD | Link Access Procedure D-channel | +| LC | Link Connection | +| LCP | Link Control Protocol | +| LL | Link Layer | +| LLCF | Link Layer Convergence Function | +| LLDP | Link Layer Discovery Protocol | +| LOVC | Lower Order Virtual Container | +| MAC | Media Access Control | +| MIB | Management Information Base | +| MPLS | Multi-Protocol Label Signalling | +| MS | Multiplex Section | +| NE | Network Element | +| NMS | Network Management System | +| OAM | Operations Administration and Maintenance | +| ODUk | Optical channel Data Unit-k | +| OTN | Optical Transport Network | +| OTUk | completely standardized Optical channel Transport Unit-k | +| PC | Protocol Controller | +| PDU | Protocol Data Unit | +| PM | Path Monitoring | +| PPP | Point-to-Point Protocol | + +| | | +|--------|---------------------------------------------| +| RS | Regenerator Section | +| SAPI | Source Access Point Identifier | +| SDH | Synchronous Digital Hierarchy | +| SM | Section Monitoring | +| SNP | Subnetwork Point | +| STM | Synchronous Transport Module | +| TAP | Termination and Adaptation Performer | +| TCE | Transport entity Capability Exchange | +| TCM | Tandem Connection Monitoring | +| TCP | Termination Connection Point | +| TCP-ID | Termination Connection Point Identifier | +| TIM | Trace Identifier Mismatch | +| TLV | Type-Length-Value | +| TT | Trail Termination | +| TTI | Trail Trace Identifier | +| UDP | User Datagram Protocol | +| UI | Unnumbered Information | +| UITS | Unacknowledged Information Transfer Service | +| WDM | Wavelength Division Multiplexing | + +# 5 Discovery methodology + +The discovery methodology uses the processes specified in clauses 6 to 12 to determine the termination connection point- (TCP)- to-TCP relationship. Once the TCP-to-TCP relationship is determined, the connection point- (CP)- to-CP connectivity relationships are derived using local information. The following two discovery methods are defined. + +### a) *Link discovery process using server trail overhead method* + +In this process, the server layer trail overhead is used to discover the peer TCPs (e.g., TCP3S to TCP3R in Figure 1). The server layer trail overhead is used to carry the discovery message (DM). The CP-to-CP relationships are inferred from the TCP-to-TCP relationships using local knowledge of the configuration of the adaptation function and its relationship with the trail termination (TT) function. This process does not disrupt the client signal being carried by the link. + +## b) *Link discovery process using client layer payload method* + +In this process, a signal is injected into the client layer payload to discover the peer TCPs (e.g., TCP1S to TCP1R in Figure 1). The CP-to-CP relationship is inferred from the local knowledge of the matrix connection that was previously set up to connect the test signal to the desired CP (shown in Figure 1). In contrast to the link discovery process using the server trail overhead, this approach may impact the client traffic being carried in the LC. + +![Diagram illustrating entities in in-service and out-of-service discovery processes. It shows two layers: Client layer and Server layer. In the Client layer, a 'Test signal carried in client payload' is shown between two client nodes. A 'Client payload method' is indicated by a double-headed arrow. In the Server layer, a 'Test signal carried in trail overhead' is shown between two server nodes. A 'Server trail overhead method' is indicated by a double-headed arrow. Between the layers, there are connection points (CPs) labeled CP2S and CP2R. These are connected to 'MATRIX' blocks. The 'Relation being discovered' is shown as a dashed red line between the two MATRIX blocks. Arrows labeled 'Inferred' point from the CPs to the MATRIX blocks. The diagram is labeled G.7714.1-Y.1705.1(15)_F01.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Diagram illustrating entities in in-service and out-of-service discovery processes. It shows two layers: Client layer and Server layer. In the Client layer, a 'Test signal carried in client payload' is shown between two client nodes. A 'Client payload method' is indicated by a double-headed arrow. In the Server layer, a 'Test signal carried in trail overhead' is shown between two server nodes. A 'Server trail overhead method' is indicated by a double-headed arrow. Between the layers, there are connection points (CPs) labeled CP2S and CP2R. These are connected to 'MATRIX' blocks. The 'Relation being discovered' is shown as a dashed red line between the two MATRIX blocks. Arrows labeled 'Inferred' point from the CPs to the MATRIX blocks. The diagram is labeled G.7714.1-Y.1705.1(15)\_F01. + +**Figure 1 – Entities in the in-service and out-of-service discovery processes** + +The discovery methodology, namely the information elements, message formats and the transport mechanisms, described in clause 5.1 is identical for both processes. + +## 5.1 CP-CP connectivity relationships determination + +The goal of the LAD process is to discover the relationship between connection points CP2S and CP2R as shown in Figure 1. This can be indirectly inferred by means of either: + +- discovering the relationship between TCP1S and TCP1R (using the out-of-service discovery mechanism); or +- discovering the relationship between TCP3S and TCP3R (using the in-service discovery mechanism). + +Once the TCP-to-TCP relationship is determined, CP-to-CP connectivity must be inferred or derived using local information of the CP-TCP bindings. This information (i.e., the name binding between CP2S and TCP1S/3S as well as between CP2R and TCP1R/3R) is pre-provisioned and resides in the equipment. + +NOTE – A validation method for optical transport network (OTN) name-binding relationships is for further study. + +# 6 Mechanisms for layer adjacency discovery + +## 6.1 Layer adjacency discovery of transport entities + +The mechanisms defined to support the LAD process apply on a per layer basis. Within each of the layer networks that support the discovery process, different mechanisms are available. These may reuse the available embedded communication channels (ECCs) for the particular layer. The following mechanisms are applicable to synchronous digital hierarchy (SDH) layer network transport entities: + +- RS layer – within the regenerator section (RS) layer, the J0 section trace and section data communications channel (DCC) may be used to support discovery of the RS TCP-to-TCP adjacency; + +- MS layer – within the multiplex section (MS) layer, the multiplex section DCC may be used to support discovery of the MS TCP-to-TCP adjacency; +- HOVC layer – within the higher order virtual container (HOVC) layer, the higher order path layer J1 trace may be used to support discovery of the HOVC TCP-to-TCP adjacency; +- LOVC layer – within the lower order virtual container (LOVC) layer, the lower order path layer J2 trace may be used to support discovery of the LOVC TCP-to-TCP adjacency. + +The following mechanisms are applicable to the OTN layer network transport entities. + +- OTUk layer – within the completely standardized optical channel transport unit-k (OTUk) layer, the section monitoring (SM) byte and the general communications channel- (GCC-) 0 may be used to support discovery of the OTUk adjacency. Specifically, the source access point identifier (SAPI) subfield within the SM is used to carry the DM. +- ODUk layer – within the optical channel data unit-k (ODUk) layer, the path monitoring (PM) byte and the GCC-1 and GCC-2 bytes may be used to support discovery of the ODUk adjacency. Specifically, the SAPI subfield within the PM is used to carry the DM. +- ODUkT layer – within the ODUkT sublayers, the trail trace identifier (TTI) field may be used to support discovery of the ODUk adjacency. By default, the ODU tandem connection monitoring (TCM) sublayer 6 (TCM6) is used for discovery. Specifically, the SAPI subfield within the TTI field is used to carry the DM. + +The following mechanisms are applicable to ITU-T G.8010 Ethernet (ETH) layer network transport entities: + +- ETY layer – discovery of the Ethernet PHY (ETY) trail is performed using the client payload method. IEEE 802.1AB [link layer discovery protocol (LLDP)] operations administration and maintenance (OAM) messages are inserted at the media access control (MAC)/ETH\_A, which are carried across the ETH link. Within the LLDP messages, the chassis ID and port ID type-length-values (TLVs) are used to carry the DM identifiers. + +Appendix VI provides clarification of the network scenarios under which the various discovery mechanisms described in this Recommendation may be utilized. This includes guidelines for their usage, as well as potential associated implications. + +# 7 Attributes used in layer adjacency + +- **Discovery agent identifier** + +The discovery agent identifier (DA ID) must be unique within the context of the link being discovered. Two different representations of the DA ID exist: a discovery agent (DA; also known in [ITU-T G.7714] as a type of control entity) address and a DA name. + +- **Discovery agent address** + +Two attributes are defined to support the DA address: + +- **Data communications network context identifier** + +This represents an assigned number (a globally assigned number would be desirable). This attribute may be used in conjunction with the data communications network (DCN) address attribute to guarantee uniqueness for the DA ID. If the sending and receiving discovery agents at each end of the link are within different DCN contexts, but use the same DCN addresses, they may be unable to communicate. + +### – **DA DCN address** + +This represents the address used to identify the discovery agent. + +### – **Discovery agent name** + +This is a name that can be resolved into a DA address. The DA name may be assigned a DCN name. + +### – **TCP-ID** + +The termination connection point identifier (TCP-ID) contains the identifier for the TCP being discovered. This has only local significance within the scope of the DA. + +### – **DCN Identifier** + +The DCN identifier, or DCN ID, is a DCN name or a DCN address. When used for discovery agents, the term DA DCN ID may be used. + +# 8 Layer adjacency based on trail trace string + +The trail trace bytes (Jx in SDH or TTI in OTN) provides a mechanism to pass a message that is 16 bytes in length. Each trace byte consists of a message start bit and 7-bits for "payload". The message start bit is set for the first byte in the message and clear for all remaining bytes in the message. The payload of the first trace byte is reserved to carry a 7-bit cyclic redundancy check (CRC) for the message in SDH and is set to all zeroes in OTN. The payload of the second and subsequent bytes is the access point identifier (API), as described in [ITU-T G.831], which specifies two different formats: + +- a) one-, two- or three-character E.164; and +- b) two- or three-character b-ISO 3166 country code, with country-specific extension. + +All characters are alphanumeric characters from the ITU-T T.50 7-bit international reference version (IRV) set (with trailing NULLs or SPACEd). As a result, the second byte conforming to the two formats listed above is limited to the following characters: + +- A-Z; +- a-z; +- 0-9. + +This Recommendation defines a third type of format, which is differentiated from the ITU-T G.831-specified formats by placing a non-numerical and non-alphabetic character in the second byte of the message.1 The remaining 14 bytes are used to carry the information required by [ITU-T G.7714], namely the DA ID and TCP-ID. These 14 bytes provide 84 bits for the discovery data. + +Since the DA ID and TCP-ID are typically numbers, a method for encoding numbers into printable characters is used. Base64 encoding, as defined in [IETF RFC 2045], provides a relatively efficient method to represent 6 bits of information in a printable character, which allows existing provisioning interfaces to be used to provision the DM when required. This yields 3 nibbles or 12 bits for every two printable characters. + +Figure 2 shows the overall J0/J1/J2 or SAPI 16-byte format and depicts how the DM is formatted as compared to the ITU-T G.831 API. + +--- + +1 See Appendix IV for use cases requiring printable characters. + +![Figure 2: Auto-discovery message format within the trail trace format. The diagram shows the mapping of SDH TTI and OTN TTI bytes to ITU-T G.831 API and ITU-T G.7714.1 DM fields. It includes a detailed view of the DM payload structure with Base64 encoding of nibbles.](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +The diagram illustrates the mapping of SDH TTI and OTN TTI bytes to ITU-T G.831 API and ITU-T G.7714.1 DM fields. + +**SDH TTI** (bytes 1-8): + 1: 0 C1 C2 C3 C4 C5 C6 C7 + 2-16: 0 [Yellow Payload] b7 b6 b5 b4 b3 b2 b1 + +**OTN TTI** (bytes 0-15): + 0: 0 0 0 0 0 0 0 0 + 1-15: 0 [Yellow Payload] b7 b6 b5 b4 b3 b2 b1 + 16-31: 0 [Blue Payload] b7 b6 b5 b4 b3 b2 b1 + 32-63: [Operator specific] + +**Mapping to ITU-T G.831 API and ITU-T G.7714.1 DM:** + +- Country code:** OTN TTI bytes 0-7 map to ITU-T G.831 API Country code. +- National segment:** OTN TTI bytes 8-15 map to ITU-T G.831 API National segment. +- Discovery message:** OTN TTI bytes 16-31 map to ITU-T G.7714.1 DM Discovery message. +- Operator specific:** OTN TTI bytes 32-63 map to ITU-T G.7714.1 DM Operator specific. + +**DM Payload Structure:** + +The DM payload is divided into 14 segments (DM[1] to DM[14]). Each segment contains 8 nibbles (0-9, A-F). The nibbles are grouped into Base64 encoding blocks: + +- Base64 encoding 1: nibble[i], nibble[i+1], nibble[i+2] → b6 b5 b4 b3 b2 b1 +- Base64 encoding 2: nibble[i+3], nibble[i+4], nibble[i+5] → b6 b5 b4 b3 b2 b1 + +Example mapping for DM[1]: + Nibbles: 0 1 2 3 4 5 6 7 + Base64 1: 0 1 2 → b6 b5 b4 b3 b2 b1 + Base64 2: 3 4 5 → b6 b5 b4 b3 b2 b1 + +Figure 2: Auto-discovery message format within the trail trace format. The diagram shows the mapping of SDH TTI and OTN TTI bytes to ITU-T G.831 API and ITU-T G.7714.1 DM fields. It includes a detailed view of the DM payload structure with Base64 encoding of nibbles. + +**Figure 2 – Auto-discovery message format within the trail trace format** + +Use of the trail trace bytes for the discovery process does not necessarily mean that an in-service test is being performed. This is a consequence of sharing the trail trace bytes with other functions such as in-service connection monitoring and non-intrusive layer monitoring. If these functions are unable to handle the DM (either due to configuration or software limitation), the functions will need to be disabled while the discovery process is being performed. The interaction between the discovery process and other functions using the trail trace bytes is for further study. + +## 8.1 Discovery message formats + +The messages defined in this clause are independent of the mechanism chosen to support them. [ITU-T G.7714] defines the attributes identified through the exchange of DMs as: + +- DA ID; +- TCP-ID. + +This information can be contained directly in the message or can be derived from the message by an external process, such as a name-server. A number of formats for the DM are therefore necessary. + +To facilitate these formats, the general message format shown in Figure 3 is used. This format contains 4 bits of format ID and 80 bits of format specific data. + +![Figure 3 – General discovery message format diagram showing a bit-level layout with a 4-bit Format ID and 80-bit Format specific data field.](9b6b5924b48bf2fd5f347f88f06f45b3_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|-----------|---|---|---|----------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| +| 0 | | | | 1 | | | | | | | | | | 2 | | | | | | | | | | 3 | | | | | | | | +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | +| Format ID | | | | Format specific data | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +Figure 3 – General discovery message format diagram showing a bit-level layout with a 4-bit Format ID and 80-bit Format specific data field. + +**Figure 3 – General discovery message format** + +This Recommendation defines formats 1, 2, 3 and 4 as defined in clauses 8.1.1 to 8.1.4. Additional formats may be provided in the future. If a DM is received with unknown format IDs, the message should be discarded. + +### 8.1.1 TCP name format + +The TCP name format contains a TCP name. The sending and receiving discovery agents are part of a federation that provides a name-server allowing the name to be uniquely resolved into the discovery agent DCN address and TCP-ID. The namespace may be subdivided among different name servers that are responsible for resolving names within the assigned parts of the name space. The format of the name is defined by the context of the name server, and is not specified here. + +The sender and receiver are required to have *a priori* knowledge of the common context for the name. The context defines the method to uniquely resolve the name. The method for resolving the received names into the address of the remote discovery agent and the remote TCP-ID is outside the scope of this Recommendation. The address of the name-server that performs the resolution is a well-known attribute that is scoped per trail. This means that the name-server can be different for each trail terminating a DM. + +The DM to be used with the TCP-ID name format is shown in Figure 4. This format contains 4 bits of format ID and 80 bits of TCP name. + +![Figure 4 – TCP-ID name message format diagram showing a bit-level layout with Format ID set to 0001 and an 80-bit TCP name to look up field.](18722c46c9e8475524e634dedd08bac2_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|---|---|---|---|---------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| +| 0 | | | | 1 | | | | | | | | | | 2 | | | | | | | | | | 3 | | | | | | | | +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | +| 0 | 0 | 0 | 1 | TCP name to look up | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +Figure 4 – TCP-ID name message format diagram showing a bit-level layout with Format ID set to 0001 and an 80-bit TCP name to look up field. + +**Figure 4 – TCP-ID name message format** + +This approach allows the internal distribution of discovery agents to be hidden from the receiving discovery agent. It also allows a discovery agent to manage TCP-ID name spaces larger than 32 bits. + +### 8.1.2 DA DCN address format + +The DA DCN address format contains the actual discovery agent ID and TCP-ID values. The discovery agent ID consists of a DCN context ID2 as well as the DCN address of the sending discovery agent. The remainder of the message contains a TCP-ID, which has local significance to the discovery agent transmitting the DM. This is called the local TCP-ID. + +The DM to be used with the DA DCN address format is shown in Figure 5. This format contains 4 bits of format ID, 16 bits of DA DCN context ID, 32 bits of DA DCN address and 32-bits of TCP-ID. + +![](1a827b10290f33d4fec04d0e8ef7a897_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|-----------------------|---|---|---|-------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|----------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|--| +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 2 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 3 | 0 | 1 | | +| 0 | 0 | 1 | 0 | DA DCN context ID | | | | | | | | | | | | | | | | DA DCN address | | | | | | | | | | | | | | | | +| DA DCN address cont'd | | | | | | | | | | | | | | | | | | | | Local TCP-ID | | | | | | | | | | | | | | | | +| Local TCP-ID cont'd | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +**Figure 5 – DA DCN address message format** + +The use of this format is recommended when the distribution of the discovery agents is not hidden, and the DCN addresses as well as the TCP-IDs used by a discovery agent can fit within 32 bits. + +### 8.1.3 DA DCN name format + +Similar to the DA DCN address format, the DA DCN name format also contains the discovery agent name and the TCP-ID value. However, unlike the DCN address format, the discovery agent name is in the form of a DCN name. Consequently, a name-server must be used to translate the DCN name into the DCN address of the discovery agent. + +As with the TCP-ID name format, the sending and receiving discovery agents are part of a federation that provides a name-server allowing the name to be uniquely resolved into the discovery agent DCN address and TCP-ID. The namespace may be subdivided among different name-servers that are responsible for resolving names within the assigned parts of the name space. The format of the name is defined by the context of the name-server, and is not specified here. + +The remainder of the message contains the local TCP-ID, which has local significance to the discovery agent transmitting the DM. + +The DM to be used with the DA DCN name format is shown in Figure 6. This format contains 4 bits of format ID, 48 bits of DA DCN name and 32 bits of TCP-ID. + +![](96b0240f56d14453b5da05ec30fd5c6e_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|---------------------------------|---|---|---|--------------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|--------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|--| +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 2 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 3 | 0 | 1 | | +| 0 | 0 | 1 | 1 | Discovery agent DCN name | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| Discovery agent DCN name cont'd | | | | | | | | | | | | | | | | | | | | Local TCP-ID | | | | | | | | | | | | | | | | +| Local TCP-ID cont'd | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +**Figure 6 – DA DCN name message format** + +2 The DCN context ID defines the context of the received DCN address. This value is included in the discovery message to aid in the debugging of the discovery process and is not interpreted by the receiving discovery agent. If the sending and receiving discovery agents at each end of the link are within different DCN contexts, but use the same DCN addresses, they may be unable to communicate. This ID may be, for example, a 2-byte Internet AS-Number as defined in [b-IETF RFC 1930]. If the DCN context ID has not been configured, then the value of 0 is used. + +Unlike the TCP-ID name format, the discovery agent responsible for the TCP-ID value provided in this DM format is not hidden. Use of this format is recommended when the TCP-IDs, used by a discovery agent, can fit within 32 bits, but the DA DCN address cannot fit within 32 bits. This format also allows for independent reconfiguration of the DCN addresses used to reach the DA. + +#### 8.1.4 ETH MAC address format + +Similar to the DCN address format, the ETH MAC name format also contains the discovery agent ID and the TCP-ID value. However, unlike the DCN address format, the discovery agent ID can have different types including: a chassis ID or an Ethernet MAC address. Consequently, a name-server may be needed to translate the DCN name into the DCN address of the discovery agent. + +The DM also contains the local TCP-ID, which has local significance to the transmitting discovery agent. As with the chassis ID, the local TCP-ID can have different types, including: an Ethernet MAC address or an interface index. + +A DM format has been defined for backward compatibility with SDH and OTN discovery agents making it possible to configure LLDP parameters without specifically supporting the LLDP management information base (MIB). This format, shown in Figure 7, contains 4 bits of format ID, containing a 48-bit Ethernet MAC address to be used for chassis ID and a 32-bit interface-index to be used as the port ID. + +![](33a8f3f01dfa8bce75d23017855a13c5_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|----------------------------------------|---|---|---|---------------------------------|---|---|---|---|---|---|---|---|---|-----------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 2 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 3 | 0 | 1 | +| 0 | 1 | 0 | 0 | Chassis ID Ethernet MAC address | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| Chassis ID Ethernet MAC address cont'd | | | | | | | | | | | | | | Port ID ifIndex | | | | | | | | | | | | | | | | | | | | | +| Port ID ifIndex cont'd | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +**Figure 7 – ETH MAC address message format** + +This message is never actually sent in an LLDP message. Instead, it is used by a discovery agent to provide a network element (NE) with the chassis ID and port ID values for transmission in LLDP messages. + +# 9 Layer adjacency based on embedded control channel messages + +There are two functions required to realize embedded communication channel- (see [ITU-T G.7712]; ECC-) based LAD: the ECC link layer convergence function (LLCF) and LAD protocol control function. These messages are applied to the specific layer adjacency that is being discovered. Note that the ECC is provided by a technology-specific mechanism as specified in clause 6. + +Figure 8 illustrates the header and data information included in each layer. + +![Figure 8: Layer adjacency discovery functions of importance for ECC messages. The diagram shows two network elements connected by an ECC link connection. Each element has a stack of layers: Physical layer, Data link protocol, LLCF protocol, Discovery message, and Adjacency attributes. The diagram illustrates the encapsulation of a Discovery message (DM PDU) through the layers. On the left, the DM PDU is encapsulated into an LLCF header, which is then encapsulated into an LL header, LLCF header, DM PDU, and LL trailer by the Data link protocol. On the right, the process is reversed. The Physical layer is connected to the Data link protocol, which is connected to the LLCF protocol, which is connected to the Discovery message, which is connected to the Adjacency attributes. The ECC link connection is shown between the Physical layers of the two network elements.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Figure 8: Layer adjacency discovery functions of importance for ECC messages. The diagram shows two network elements connected by an ECC link connection. Each element has a stack of layers: Physical layer, Data link protocol, LLCF protocol, Discovery message, and Adjacency attributes. The diagram illustrates the encapsulation of a Discovery message (DM PDU) through the layers. On the left, the DM PDU is encapsulated into an LLCF header, which is then encapsulated into an LL header, LLCF header, DM PDU, and LL trailer by the Data link protocol. On the right, the process is reversed. The Physical layer is connected to the Data link protocol, which is connected to the LLCF protocol, which is connected to the Discovery message, which is connected to the Adjacency attributes. The ECC link connection is shown between the Physical layers of the two network elements. + +**Figure 8 – Layer adjacency discovery functions of importance for ECC messages** + +Two mechanisms are available at the ECC based on the link layer protocol that is supported. + +## 9.1 LAPD-based mechanism + +[b-ITU-T G.784] requires both acknowledged information transfer service (AITS) and unacknowledged information transfer service (UITS) modes to be supported by every NE, so they can be utilized simultaneously over a single ECC channel. The LLCF uses link access procedure D-channel (LAPD) UITS for transport of LAD information. The interface from LLCF to LAPD utilizes DL\_UNIT DATA primitives to request the transmission of unnumbered information frames. This discovery information is transferred between peer entities, employing the message used in the point-to-point protocol (PPP) transport. + +The sending of DL\_UNIT DATA primitives can occur at any time and does not affect the LAPD state machine, permitting the OSI/IP network layer to continue using AITS, if desired. Therefore, the DMs can be sent even in the cases where only unidirectional link exists or miswiring of a bidirectional connection. + +The payload of this string shall be as defined for the trace (see clause 8) and shall interwork with PPP receivers. + +## 9.2 PPP-based mechanism + +Message exchange over PPP shall conform to [IETF RFC 1570] and [ITU-T G.7712] ([b-IETF RFC 1661] and [IETF RFC 1662]) using the identification message [link control protocol (LCP) code-point 12] defined in [IETF RFC 1570]. The payload of this string shall be as defined for the trace (see clause 8) and shall interwork with LAPD receivers. + +## 9.3 Interoperable solution when using ECC based mechanism + +When utilizing high-level data link control (HDLC; in SDH) over the ECC for discovery as described in clauses 9.1 and 9.2, the HDLC address field of the frame shall be used to distinguish between LAPD and PPP link layer frames using the second octet of the frame. + +In a PPP frame the address field is set to a fixed value of All-Stations (single octet value 0xff) as specified in [IETF RFC 1662], whereas the address field (second octet) of the LAPD frame can never have a single octet value of 0xff. PPP MUST NOT be permitted to negotiate Address-and-Control-Field-Compression as outlined in clause 3.2 of [IETF RFC 1662] to allow both link layer protocols to function simultaneously over the ECC. + +A PPP-only NE acting as a receiver would distinguish the adjacency discovery LAPD frame (based on contents of the HDLC address field), pass it through a trivial LAPD link layer to remove the fixed LAPD header fields, and pass the information field to the discovery agent. No other LAPD frames would need to be supported by a PPP-only NE. + +On transmission the trivial LAPD link layer would place the local NE's discovery data in the LAPD type B unnumbered information packet information field with the specific addressing for discovery and pass it to HDLC for sending over the ECC. + +When LAPD is used for discovery, a SAPI/terminal endpoint identifier (TEI) of 61/0 shall be used for DMs. This is different than the 62/0 used by OSI/LAPD over the DCC, as the unnumbered information (UI) frames for discovery could be mistaken for OSI protocol data units (PDUs). + +![Diagram illustrating ECC-based layer adjacency discovery using LAPD between NE A and NE B. The process involves four steps: 1) DL-UNIT DATA request from DA to ECC LAPD in NE A; 2) ECC in-band discovery message using LAPD UI frame (second octet not 0xFF) from ECC LAPD in NE A to NE B; 3) DL-UNIT DATA indication from ECC PPP to DA in NE B, with a link layer check for the second octet; 4) Out-of-band discovery response message from DA to PC in NE B, then to PC in NE A, and finally to DA in NE A.](8fa679f79a1bb1f527cba9f29e784e89_img.jpg) + +The diagram shows the interaction between two network elements, NE A and NE B, connected by a central control channel. + - **NE A (Left):** Contains a Discovery Agent (DA), a Packet Controller (PC), and an ECC LAPD block. DA sends a '1) DL-UNIT DATA request' to ECC LAPD. + - **NE B (Right):** Contains a PC, a DA, an ECC PPP block, and a Trivial LAPD block. + - **Step 1:** DA in NE A sends a 'DL-UNIT DATA request' to its ECC LAPD block. + - **Step 2:** ECC LAPD in NE A sends an 'ECC in-band discovery message using LAPD UI frame (second octet not 0xFF)' to NE B. + - **Step 3:** In NE B, the message is received by the Trivial LAPD block, which performs a 'Link layer check' on the second octet. If it is not 0xFF, it sends a 'DL-UNIT DATA indication' to the DA. + - **Step 4:** The DA in NE B sends an 'Out-of-band discovery response message' to its PC, which then forwards it through the central 'Discovery response message in control channel' to the PC in NE A, which finally passes it to the DA in NE A. + +Diagram illustrating ECC-based layer adjacency discovery using LAPD between NE A and NE B. The process involves four steps: 1) DL-UNIT DATA request from DA to ECC LAPD in NE A; 2) ECC in-band discovery message using LAPD UI frame (second octet not 0xFF) from ECC LAPD in NE A to NE B; 3) DL-UNIT DATA indication from ECC PPP to DA in NE B, with a link layer check for the second octet; 4) Out-of-band discovery response message from DA to PC in NE B, then to PC in NE A, and finally to DA in NE A. + +**Figure 9 – ECC-based layer adjacency discovery using LAPD** + +This solution does not require that a PPP-only NE implement the LAPD state machine, given the unnumbered information frame mechanism being utilized passes through the existing LAPD state machine without forcing a state transition. + +## 9.4 PPP-based support in OTN ECC + +Message exchange over the OTN ECC can be performed over GCC-0, GCC-1 and GCC-2. These are specified in clauses 15.7.2.2 and 15.8.2.3 of [ITU-T G.709]. When using GCC-1 and GCC-2 for neighbour discovery, NEs on either end of the link must have access to the ODU frame structure. As per clause 7.1.2.2.2 of [ITU-T G.7712], PPP in HDLC framing over GCC is used. + +### 9.4.1 LLDP/PPP + +For the discovery trigger and adjacency discovery, the LCP identification message of PPP is used as defined in clause 9.2. The payload of the LCP identification message is an LLDP message as described in clause 10. In the chassis ID TLV of the LLDP message, an IP address is used as the DA DCN name or address, and the port ID field is used to convey the local TCP-IDs. + +### 9.4.2 LLDP/MAC/PPP + +LLDP may also be supported over MAC layer as originally specified in [IEEE 802.1AB]. Carrying MAC frames over PPP can be accomplished using the following options in [IETF RFC 3518]. + +- 1) After LCP/NCP protocols complete, run bridging control protocol (BCP) with the MAC-Support option (3) with MAC type of 1 for [IEEE 802.3] Ethernet. + +- 2) After BCP reaches opened state, use clause 4.2 of [IETF RFC 3518] to send untagged frames. PPP bridging is specified as 0x0031 in the PPP header. The MAC type of 1 is also specified. +- 3) To send an LLDP packet in a MAC frame, fill the destination MAC with 01-80-C2-00-00-0E. This specifies the "Nearest bridge" Group MAC address for LLDP. The EtherType field is set to 0x88cc. + +Discovery information is carried in LLDP as described in clauses 9.4.1 and 10.1. + +# 10 Layer adjacency based on packet OAM frames + +## 10.1 Ethernet link discovery mechanism + +As with ECC-based LAD, there are two functions required to realize LLDP OAM frame discovery: the ETH OAM LLCF and LAD protocol control function. These OAM messages are applied to the Ethernet link being discovered. + +Figure 10 illustrates the header and data information included by each layer. + +![Diagram illustrating the Layer adjacency discovery functions of importance for ETH link discovery. It shows two Network elements connected by an ETH link connection. The left Network element has layers: Adjacency attributes, Discovery attributes, LLDP protocol, Data link protocol, and Physical layer. The right Network element has layers: Adjacency attributes, Discovery attributes, LLDP protocol, Data link protocol, and Physical layer. The diagram shows the flow of data from the left side to the right side, with DM data being added at the Discovery attributes layer and LLDP header being added at the LLDP protocol layer. The Physical layer is connected to the ETH link connection.](2eb23c2210154279f8013a1594fbcc5a_img.jpg) + +The diagram illustrates the encapsulation and transmission of LLDP frames between two Network elements (NEs) over an Ethernet link. The layers involved are: + +- Adjacency attributes:** The top-level data to be transmitted. +- Discovery attributes:** Encapsulated within the Adjacency attributes. +- LLDP protocol:** Adds an LLDP header to the Discovery attributes. +- Data link protocol:** Adds an LL header to the LLDP protocol data. +- Physical layer:** The final layer for transmission over the ETH link connection. + +The right side of the diagram shows the corresponding decapsulation process, with arrows pointing upwards through the layers. A label 'G.7714.1-Y.1705.1(15)\_F10' is present at the bottom right. + +Diagram illustrating the Layer adjacency discovery functions of importance for ETH link discovery. It shows two Network elements connected by an ETH link connection. The left Network element has layers: Adjacency attributes, Discovery attributes, LLDP protocol, Data link protocol, and Physical layer. The right Network element has layers: Adjacency attributes, Discovery attributes, LLDP protocol, Data link protocol, and Physical layer. The diagram shows the flow of data from the left side to the right side, with DM data being added at the Discovery attributes layer and LLDP header being added at the LLDP protocol layer. The Physical layer is connected to the ETH link connection. + +**Figure 10 – Layer adjacency discovery functions of importance for ETH link discovery** + +The encoding of the DM is as defined in [IEEE 802.1AB] (LLDP). The outgoing PDU shall utilize destination and source MAC addresses as defined in clauses 7.1 and 7.2, respectively, of [IEEE 802.1AB] and carry the mandatory chassis ID, port ID, time-to-live and end of LLDP PDU TLVs. The chassis ID field is used to convey the DA DCN name or DA DCN address, and the port ID field is used to convey the local TCP-IDs. + +Since LLDP is a one-way, transmit-only protocol, there is no mechanism for active bidirectional link detection or transport entity capability exchange (TCE) negotiation. However, passive TCE negotiation is possible. In this approach, the negotiation process does not actively exchange proposed, accepted and not-accepted configuration parameters. Instead, the process uses a well-defined set of behaviours that all NEs follow to determine configuration given the parameters provided. + +As an example of passive negotiation, LLDP has an optional TLV to convey the maximum frame size supported by a port. Instead of specifically stating what size peer to use, with acknowledge or negative-acknowledge (ACK/NAK) exchanges, this option provides the peer with the max frame size supported and it is expected that the peer will observe that limit. + +## 10.2 MPLS-TP transport entity discovery mechanism + +For further study. + +# 11 Procedures + +The discovery methods and procedures described in this clause are independent of the transport mechanism. The procedure for LAD is as follows: + +- 1) the initiating discovery agent transmits the DM, populating the attributes as required within clause 7; +- 2) upon receiving an appropriately formatted DM, the responding DA checks to determine the applicability of the message using the distinguishing character to validate the DM; +- 3) after determining that the received message is a DM, the responding discovery agent then determines whether the values received are unique with respect to already discovered neighbours as follows: + - i) if the DM uses a TCP-ID name format, a name-server is needed to determine the DA DCN address and TCP-ID, + - ii) if the DM uses a format containing the DA DCN Address, then no further address translation is needed, + - iii) if the DM uses a format containing a DA DCN Name, then address translation is needed to convert the DA DCN name into a DA DCN Address; +- 4) when active discovery is in use, generate a discovery response message. + +# 12 Discovery response message + +When the discovery agent receives the DM for the first time, it may notify the originating discovery agent using the discovery response message that the message was received on a TT associated with a particular TCP. This TCP, called the discovery sink TCP, is identified in the response using the discovery information currently being sent on the TCP. Additional optional attributes may be included as a part of an implementation. The discovery response message is sent using the DCN. It may also be sent in-band if the technology is capable of that. See Table 1. + +**Table 1 – Discovery response message attributes** + +| | | +|----------------------|-----------------------------------------------------------------| +| | DA DCN ID contained in the received DM | +| | TCP-ID contained in the received DM | +| | DA DCN ID actively being sent by the responding discovery agent | +| | TCP-ID actively being sent by the responding discovery agent | +| | Identifier for the TCP on which the DM was received | + +The received DA DCN ID field shall be included in the discovery response if the following condition is met: the received DM includes a DA DCN ID. If the DA DCN ID is a DCN name, the name must be copied exactly into the response message and not be translated when being sent in the discovery response. This attribute shall not be included if a DA DCN ID was not included in the received DM (i.e., the TCP-ID format is in use). + +The sent DA DCN ID field shall be included in the discovery response if the following condition is met: the format of the DM currently being sent on the discovery Sink TCP includes a DCN identifier. The sent DA DCN ID will contain the same DA DCN ID being sent on the discovery Sink TCP. This attribute shall not be included if the DA DCN ID is not included in the current DM being sent on the discovery Sink TCP. + +The received TCP-ID is the TCP Identifier received in the DM. The format of the TCP-ID is determined by the format of the DM that was received. + +The sent Tx TCP-ID is the TCP Identifier currently being sent in DMs on the discovery Sink TCP. The format of this identifier is determined by the format of the DM being sent. + +The sent Rx TCP-ID is the TCP identifier for the receive side of the discovery Sink TCP. The format of this identifier is the same as for the sent Tx TCP-ID. This shall always be sent with bidirectional links, allowing for different TCP-IDs to be used for the Tx and Rx directions on a Trail. It shall also be sent when the Tx and Rx TCP-IDs are the same. This attribute shall not be sent for a unidirectional TCP-endpoint. + +The DCN Address of the discovery agent to which the discovery response message is sent will be determined from the DA DCN ID received in the DM. If the format of the DM received does not include a DA DCN ID, then it is expected that a name-server function has been provided to allow the DCN Address to be looked up given the received TCP-ID. + +When the DA DCN ID received in a DM is a name, then it is expected that a name-server function has been provided to allow the DCN address to be looked up given the received DA DCN name. However, if the DA DCN ID received contains a DCN address, then the DCN address may be used directly. + +## **12.1 Miswiring detection** + +Once a DM has been received on a resource and a discovery response message describing the same resource is received over the DCN, it is possible to correlate the messages and determine whether a bidirectional link exists. If the TCP-ID corresponding to the remote endpoint of the LC is not the same in both messages, then a miswired condition exists. If the TCP-ID is the same, then the Transmit/Receive signal pair has been properly wired. This is described in greater detail in Appendix II. + +## **12.2 Misconnection detection** + +Once a bidirectional link has been discovered, it should be checked against management-provided policy to determine whether correct TCP-LC endpoints have been correctly connected. If the policy states that the TCP-LC endpoints may not be paired to form a link, then a misconnection condition exists. In absence of this policy, it is not possible to identify a misconnection condition. + +# Appendix I + +## Implementation example of discovery process + +(This appendix does not form an integral part of this Recommendation.) + +This appendix provides an implementation example intended to validate the protocol design choices made and specified in this Recommendation. + +## I.1 Layer adjacency discovery information flow + +As described in [ITU-T G.7714], the discovery process includes the following steps: + +- LAD; +- service capability exchange. + +Completing the LAD process requires a number of functions to interact to identify the TCP LC. Further, the relationship between the LAD process and the service capability exchange mechanism needs to be described. Figure I.1 is a sequence diagram detailing the interactions. + +![Sequence diagram for Figure I.1 showing interactions between various network elements including Local DA PC / DA protocol controller, Local DA / discovery agent, Local TAP / termination adaptation performer, Local TT / trail termination, Remote TT / trail termination, Remote TAP / termination adaptation performer, Remote DA / discovery agent, Local ASON controller / ASON control plane, and Local DA PC / DA protocol controller. The diagram illustrates the sequence of messages for discovery and trail trace correlation across DCN.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg) + +``` + +sequenceDiagram + participant External + participant Local_DAPC as Local DA PC / DA protocol controller + participant Local_DA as Local DA / discovery agent + participant Local_TAP as Local TAP / termination adaptation performer + participant Local_TT as Local TT / trail termination + participant Remote_TT as Remote TT / trail termination + participant Remote_TAP as Remote TAP / termination adaptation performer + participant Remote_DA as Remote DA / discovery agent + participant Local_ASON as Local ASON controller / ASON control plane + participant Local_DAPC_2 as Local DA PC / DA protocol controller + + External->>Local_DA: Management create DA + Local_DA->>Local_TAP: Request TCP mapping / capability information + Local_TAP-->>Local_DA: Receive TCP mapping / capability information + Local_DA->>Local_DAPC: Register with DCN for DA address + Local_ASON->>Local_DA: Management assign resource + Local_ASON->>Local_TAP: Configure TT trail trace + Local_TAP->>Local_TT: Configure TT trail trace + Local_TT->>Remote_TT: Send trail trace message (repeatedly) + Remote_TT->>Remote_TAP: Trail trace change notification + Remote_TAP->>Remote_DA: Provide trail trace message + Remote_DA->>Local_DAPC_2: Associate discovery response message with resource + Local_DAPC_2->>Local_ASON: Associate ASON SNP ID with DA local scope TCP ID + Local_ASON->>Local_DAPC: Deliver received message + Local_DAPC->>Local_DA: Associate discovery response message with resource + Local_DA->>Local_TAP: Provide trail trace message + Local_TAP->>Local_TT: Associate trail trace received with resource + Local_TT->>Remote_TT: Send trail trace message (repeatedly) + Remote_TT->>Remote_TAP: Trail trace change notification + Remote_TAP->>Remote_DA: Provide trail trace message + Remote_DA->>Local_DAPC_2: Send discovery response message + Local_DAPC_2->>Local_ASON: Transit message across DCN + Local_ASON->>Local_DAPC: Deliver received message + Local_DAPC->>Local_DA: Correlate discovery response message with trail trace + Local_DA->>Local_DAPC: Send capability information available + Local_DAPC->>Local_ASON: Transit message across DCN + Local_ASON->>Local_DAPC: Deliver received message + Local_DAPC->>Local_DA: Provide ASON TCP ID + Local_DAPC->>Local_ASON: Transit message across DCN + Local_ASON->>Local_DAPC: Deliver received message + Local_DAPC->>Local_ASON: Request ASON TCP ID + Local_ASON->>Local_DAPC: Transit message across DCN + Local_DAPC->>Local_ASON: Deliver received message + +``` + +Sequence diagram for Figure I.1 showing interactions between various network elements including Local DA PC / DA protocol controller, Local DA / discovery agent, Local TAP / termination adaptation performer, Local TT / trail termination, Remote TT / trail termination, Remote TAP / termination adaptation performer, Remote DA / discovery agent, Local ASON controller / ASON control plane, and Local DA PC / DA protocol controller. The diagram illustrates the sequence of messages for discovery and trail trace correlation across DCN. + +Figure I.1 – Sequence diagram + +# Appendix II + +## Miswiring detection + +(This appendix does not form an integral part of this Recommendation.) + +This appendix describes how the LAD procedure can detect that the interfaces between two NEs are miswired. In the examples of this appendix, the DA DCN address format as defined in clause 8.1.2 is used for the in-band DM. This does not, however, preclude other message formats from being used. + +## II.1 Auto-discovery procedures + +To automatically discover a layer adjacency between two NEs (e.g., NE A and NE B), both NEs have to perform the discovery procedure in order to learn the association between the local TCPs and the remote TCPs. The two discovery processes on the two NEs are executed independently, i.e., there is no specific protocol message exchange that triggers the neighbouring NE to perform the discovery process. This is depicted in Figures II.1 and II.2. Figure II.1 illustrates the discovery process that is initiated by the DA responsible for NE A, whereas Figure II.2 shows the process that is triggered by the DA responsible for NE B. When the discovery process initiated by the DA related to NE A (DA\_A) is completed (i.e., DA\_A has received the discovery response message), both DA\_A and DA\_B (DA related to NE B) have the following set of information elements: + +< DA-ID\_A, TCP-ID\_A\_t, DA-ID\_B, TCP\_ID\_B\_r, [TCP\_ID\_B\_t] > + +These information elements have the following meaning: + +- DA-ID\_A: DCN ID of DA related to NE A; +- TCP-ID\_A\_t: local TCP-ID of TCP in NE A from which the DM was transmitted; +- DA-ID\_B: DCN ID of DA related to NE B; +- TCP\_ID\_B\_r: local TCP\_ID of TCP in NE B that received the DM from NE A; +- [TCP\_ID\_B\_t]: local TCP\_ID of TCP in NE B (transmit direction) associated with TCP\_ID\_B\_r. + +![Diagram of Layer adjacency discovery procedure initiated by NE A. The diagram shows two network elements, NE A and NE B, connected by a trail overhead channel. NE A contains a DA (Data Administration) and a PC (Packet Controller). NE B also contains a DA and a PC. The discovery process is initiated by NE A. A 'Discovery message in trail overhead channel' is sent from NE A to NE B. This message contains 'TCP-ID_A_t' and 'DA DCN ID'. NE B receives this message and sends a 'Discovery response message in control channel' back to NE A. This response message contains 'TCP-ID' and 'DA DCN ID'. The process is labeled '1) In-band discovery message' for the initial message and '2) Out-of-band discovery response message' for the response. The diagram also shows internal components like switches and triangles representing network interfaces.](ea4fd10a9a501c602f2bea0f7f711877_img.jpg) + +Diagram of Layer adjacency discovery procedure initiated by NE A. The diagram shows two network elements, NE A and NE B, connected by a trail overhead channel. NE A contains a DA (Data Administration) and a PC (Packet Controller). NE B also contains a DA and a PC. The discovery process is initiated by NE A. A 'Discovery message in trail overhead channel' is sent from NE A to NE B. This message contains 'TCP-ID\_A\_t' and 'DA DCN ID'. NE B receives this message and sends a 'Discovery response message in control channel' back to NE A. This response message contains 'TCP-ID' and 'DA DCN ID'. The process is labeled '1) In-band discovery message' for the initial message and '2) Out-of-band discovery response message' for the response. The diagram also shows internal components like switches and triangles representing network interfaces. + +Figure II.1 – Layer adjacency discovery procedure initiated by NE A + +When the discovery process initiated by the DA related to NE B (DA\_B) is completed (i.e., DA\_B has received the discovery response message), both DA\_B and DA\_A have the following set of information elements: + +< DA-ID\_B, TCP-ID\_B\_t, DA-ID\_A, TCP\_ID\_A\_r, [TCP\_ID\_A\_t] > + +These information elements have the following meaning: + +- DA-ID\_B: DCN ID of DA related to NE B; +- TCP-ID\_B\_t: local TCP-ID of TCP in NE B from which the DM was transmitted; +- DA-ID\_A: DCN ID of DA related to NE A; +- TCP\_ID\_A\_r: local TCP\_ID of TCP in NE A that received the DM from NE B; +- [TCP\_ID\_A\_t]: local TCP\_ID of TCP in NE A (transmit direction) associated with TCP\_ID\_A\_r. + +![Diagram of Layer adjacency discovery procedure initiated by NE B. The diagram shows two network elements, NE A and NE B, each containing a DA (Data Administration) and a PC (Packet Control) component. NE B initiates the process with an 'In-band discovery message' (1) sent from its DA to NE A's DA via the control channel. NE A responds with a 'Discovery response message in control channel' (2) from its DA to NE B's DA. Below the control channel, a 'Discovery message in trail overhead channel' is shown, containing 'DA DCN ID' and 'TCP-ID' fields. Arrows indicate the flow of these messages between the DAs and PCs. Labels TCP-ID_A_r and TCP-ID_B_t are present near the bottom of the diagram, indicating the local TCP-IDs used in the discovery process.](58f4167687de8d7339594e5f6fbe0bc6_img.jpg) + +Diagram of Layer adjacency discovery procedure initiated by NE B. The diagram shows two network elements, NE A and NE B, each containing a DA (Data Administration) and a PC (Packet Control) component. NE B initiates the process with an 'In-band discovery message' (1) sent from its DA to NE A's DA via the control channel. NE A responds with a 'Discovery response message in control channel' (2) from its DA to NE B's DA. Below the control channel, a 'Discovery message in trail overhead channel' is shown, containing 'DA DCN ID' and 'TCP-ID' fields. Arrows indicate the flow of these messages between the DAs and PCs. Labels TCP-ID\_A\_r and TCP-ID\_B\_t are present near the bottom of the diagram, indicating the local TCP-IDs used in the discovery process. + +**Figure II.2 – Layer adjacency discovery procedure initiated by NE B** + +In order to perform miswiring detection, it is necessary that both discovery processes on the two neighbouring NEs (NE A and NE B) have completed. Once both DA\_A and DA\_B have reached this state, they both have the following two sets of information elements that can be correlated for miswiring detection on either side (see Figure II.4): + +- < DA-ID\_A, TCP-ID\_A\_t, DA-ID\_B, TCP\_ID\_B\_r, [TCP\_ID\_B\_t] > and +- < DA-ID\_B, TCP-ID\_B\_t, DA-ID\_A, TCP\_ID\_A\_r, [TCP\_ID\_A\_t] > + +From the perspective of DA\_A, the two sets of information elements that are bound to the same local pair of TCPs need to be found in a first step. This can be done based on the local TCP-IDs that were locally assigned to the TCPs (TCP\_ID\_A\_t in the transmit direction, i.e., from NE A to NE B and TCP-ID\_A\_r in the receive direction, i.e., from NE B to NE A). When the two information element sets are identified that are locally bound together, the following consistency checks can be performed: + +- Check whether the DA-IDs are the same on both sides. +- Check whether the remote TCP-IDs (TCP-ID\_B\_t and TCP-ID\_B\_r) are also bound to the correct TCPs on the remote side. + +Depending on whether the same TCP-ID value is used for the remote TCPs in transmit and receive direction or whether they both have different values, the DA\_A needs to know the binding between the two TCP-IDs on the remote side. If the remote TCP-IDs in the transmit and receive direction are the same (TCP-ID\_B\_t = TCP-ID\_B\_r) the remote DA (DA\_B) does not need to include the TCP-ID in the transmit direction (TCP-ID\_B\_t) in the discovery + +response message. If the remote TCP-IDs are different ( $TCP-ID\_B\_t \neq TCP-ID\_B\_r$ ), the remote DA ( $DA\_B$ ) must include the optional TCP-ID in the transmit direction ( $TCP-ID\_B\_t$ ) in the discovery response message. + +The DA-ID check ensures that the same two DAs are involved in the discovery process in both directions (the one initiated by $DA\_A$ and the one initiated by $DA\_B$ ). This also ensures that the scope of the TCP-IDs is the same. It shall be noted that the TCP-IDs only have local significance and are only unique within the scope of a single DA. + +When the DA-ID check is passed successfully, the consistency check on the remote TCP-IDs can be performed. It checks whether the pairs of remote TCP-IDs received via the out-of-band discovery response message and the in-band DM from $DA\_B$ are consistent. + +In the two examples shown in Figure II.3 and Figure II.4, the TCP-IDs in transmit and receive direction on both NE A and NE B are the same. In Figure II.3, the wiring between NE A and NE B is correct. In Figure II.4, the interfaces I/F n and I/F m on NE A and the interfaces I/F k and I/F l on NE B are miswired. Table II.1 and Table II.2 contain the corresponding sets of discovery information $DA\_A$ has obtained after the DM exchange. + +![Figure II.3: Auto-discovery in case of correctly wired interfaces. The diagram shows two network elements, NE A and NE B, each containing a DA (Discovery Agent) and an interface (I/F n for NE A, I/F k for NE B). DA_A in NE A sends a discovery message (1a) to DA_B in NE B via I/F n. DA_B in NE B sends a discovery message (1b) to DA_A in NE A via I/F k. DA_A in NE A sends an out-of-band discovery response message (2a) to DA_B in NE B. DA_B in NE B sends an out-of-band discovery response message (2b) to DA_A in NE A. The diagram also shows TCP-IDs: TCP-ID_A_t (=14) and TCP-ID_A_r (=14) for DA_A, and TCP-ID_B_r (=11) and TCP-ID_B_t (=11) for DA_B. The wiring is correct as the discovery messages and response messages are received by the correct DAs.](e90987faabad6a6665cd8ed1151dc474_img.jpg) + +Figure II.3: Auto-discovery in case of correctly wired interfaces. The diagram shows two network elements, NE A and NE B, each containing a DA (Discovery Agent) and an interface (I/F n for NE A, I/F k for NE B). DA\_A in NE A sends a discovery message (1a) to DA\_B in NE B via I/F n. DA\_B in NE B sends a discovery message (1b) to DA\_A in NE A via I/F k. DA\_A in NE A sends an out-of-band discovery response message (2a) to DA\_B in NE B. DA\_B in NE B sends an out-of-band discovery response message (2b) to DA\_A in NE A. The diagram also shows TCP-IDs: TCP-ID\_A\_t (=14) and TCP-ID\_A\_r (=14) for DA\_A, and TCP-ID\_B\_r (=11) and TCP-ID\_B\_t (=11) for DA\_B. The wiring is correct as the discovery messages and response messages are received by the correct DAs. + +Figure II.3 – Auto-discovery in case of correctly wired interfaces + +Table II.1 – Example of the two sets of discovery information from the perspective of $DA\_A$ for the correctly wired case depicted in Figure II.3 + +| Process Initiator | | Received TCP-ID associated with interface n | | associated with interface k | Optional associated with interface k/n | +|-------------------|----------------------|---------------------------------------------|------------------|----------------------------------------------|---------------------------------------------------------| +| $DA\_A$ | $DA-ID\_A$ | $TCP-ID\_A\_t$ | $DA-ID\_B$ | $TCP-ID\_B\_r$ | $TCP-ID\_B\_t$ | +| Value | 1 | 14 | 2 | 11 | 11 | +| $DA\_B$ | $DA-ID\_B$ | $TCP-ID\_B\_t$ | $DA-ID\_A$ | $TCP-ID\_A\_r$ | $TCP-ID\_A\_t$ | +| Value | 2 | 11 | 1 | 14 | 14 | + +![Figure II.4: Auto-discovery in case of miswired interfaces. The diagram shows two network elements, NE A and NE B, each containing a Data Aggregator (DA) and two interfaces (I/F n, I/F m for NE A; I/F k, I/F l for NE B). Discovery messages (1a, 1b) and out-of-band discovery response messages (2a, 2b) are shown between the DAs. TCP-IDs are assigned to interfaces: TCP-ID_A_t and TCP-ID_A_r for NE A (both = 14); TCP-ID_B_r and TCP-ID_B_t for NE B (both = 11). The diagram illustrates a miswiring scenario where the discovery process detects inconsistent TCP-IDs.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg) + +Figure II.4: Auto-discovery in case of miswired interfaces. The diagram shows two network elements, NE A and NE B, each containing a Data Aggregator (DA) and two interfaces (I/F n, I/F m for NE A; I/F k, I/F l for NE B). Discovery messages (1a, 1b) and out-of-band discovery response messages (2a, 2b) are shown between the DAs. TCP-IDs are assigned to interfaces: TCP-ID\_A\_t and TCP-ID\_A\_r for NE A (both = 14); TCP-ID\_B\_r and TCP-ID\_B\_t for NE B (both = 11). The diagram illustrates a miswiring scenario where the discovery process detects inconsistent TCP-IDs. + +Figure II.4 – Auto-discovery in case of miswired interfaces + +Table II.2 – Example of the two sets of discovery information from the perspective of DA\_B for the miswired case depicted in Figure II.4 + +| Process Initiator | | Received TCP-ID associated with interface n | | associated with interface k | Optional associated with interface k/n | +|-------------------|----------------------|---------------------------------------------|------------------|----------------------------------------------|---------------------------------------------------------| +| DA_A | DA-ID_A | TCP-ID_A_t | DA-ID_B | TCP-ID_B_r | TCP-ID_B_t | +| Value | 1 | 14 | 2 | 11 | 11 | +| DA_B | DA-ID_B | TCP-ID_B_t | DA-ID_A | TCP-ID_A_r | TCP-ID_A_t | +| Value | 2 | 12 | 1 | 14 | 14 | + +The values given in Table II.1 show that the two sets of discovery information from the perspective of DA\_A belong together because the local TCP-ID\_A\_t and TCP-ID\_A\_r have the same value (TCP-ID\_A\_t = TCP-ID\_A\_r = 14) and hence, are related to the same bidirectional TCP. In the next step, the DA-ID consistency check is performed. In the examples given, the information sets are DA-consistent because the sent and received DA DCN IDs (1-2 and 2-1) indicate that the same two DAs are involved in the discovery process. Finally, whether the remote TCP-IDs (from the DA\_A perspective) refer to the same remote TCP is checked. In the example, the check leads to a positive result, since TCP-ID\_B\_r and TCP-ID\_B\_t are equal and both have the same value 11 in the two discovery information sets. + +In the second example, all the checks are passed successfully, as in the previous example, except the final remote TCP consistency check. This final TCP-ID check reveals that the remote TCP-IDs (from the perspective of DA\_A) do not refer to the same remote TCP, because TCP-ID\_B\_r and TCP-ID\_B\_t have different values (11 in the out-of-band discovery response message versus 12 in the in-band DM). Hence, DA\_A can indicate the detected miswiring by raising an appropriate alarm, for example. + +## II.2 Example: Interaction between two DAs using different DM formats + +The procedure also works when two DAs actively engaged in discovering a link are using different DM formats. This example shows one discovery agent using TCP name format, while the other is using DCN DA address format. + +![Sequence diagram showing the interaction between two Discovery Agents (DAs) and a Federated Nameserver. The initiating DA uses TCP name format (Fmt=1), while the responding DA uses DCN DA address format (Fmt=2).](dcb5711d118ae6753b0e12f86eda37db_img.jpg) + +``` + +sequenceDiagram + participant IDA as Initiating DA / discovery_agent + participant RDA as Responding DA / discovery_agent + participant NS as Feder. Nameserver/ TCPID Nameserver + + IDA->>RDA: Disc(Fmt=1, TCPID=0x00000000000008675309) + RDA->>NS: Lookup(TCPID=0x00000000000008675309) + Note over RDA: Associate discovery message with discovery Sync TCP + NS-->>RDA: LookupResp(DA DCN Addr=2.1.3.4, TCPID=0x00000000000008675309) + Note over RDA: Associate discovery response message with discovery sync TCP + RDA->>IDA: DiscResp(RCV TCPID=0x00000000000008675309, SND DA DCNID=2.3.4.1, SND Tx TCP ID=0x00000012, SND Rx TCPID=0x00000042) + Note over IDA: Associate discovery response message with discovery sync TCP + IDA->>RDA: Disc(Fmt=2, DA DCN ID=2.3.4.1, TCPID=0x00000012) + Note over IDA: Associate discovery message with Disc Sync TCP + IDA->>RDA: DiscResp(RCV DA DCNID=2.3.4.1, RCV TCPID=0x00000012, SND Tx TCPID=0x00000000000008675309, SND Rx TCPID=0x00000000000007365000) + Note over RDA: Associate discovery response message with Disc Sync TCP + Note over RDA: Correlate discovery with discovery response + Note over IDA: Correlate discovery with discovery response + +``` + +G.7714.1-Y.1705.1(15)\_FII.5 + +Sequence diagram showing the interaction between two Discovery Agents (DAs) and a Federated Nameserver. The initiating DA uses TCP name format (Fmt=1), while the responding DA uses DCN DA address format (Fmt=2). + +**Figure II.5 – Sequence for discovery between two DAs using different message formats** + +In this example, the initiating discovery agent sends a DM in TCP name format. The DM *DISC(Fmt=1, TCPID=0x00000000000008675309)* is sent in band to the responding discovery agent. When received by the responding discovery agent, the Rx TCP (*0x42*) on which the DM was received is recorded. This is called the Sink TCP. + +The TCP name (*0x00000000000008675309*) in the received DM is then translated into the DA DCN address for the initiating discovery agent (*address = 2.1.3.4*) and TCP-ID (*0x00000000000008675309*) using a name-server. + +Once the DA DCN address is known, a discovery response message is returned to the initiating discovery agent. The discovery response message includes the attributes in the received DM, the attributes that are currently being sent on the Tx TCP (*Fmt=2, DA DCN Address=2.3.4.1, Tx TCPID=0x0000 0012*) related to the Sink TCP, as well as the TCP-ID for the Sink TCP (*Rx TCPID=0x0000 0042*). Once received by the initiating discovery agent, a unidirectional LC has been identified. + +This process is repeated for the opposite direction. However, since this time the DA DCN address format is being used, the DM *DISC (Fmt=2, DA DCN Address=2.3.4.1, TCPID=0x0000 0012)* sent includes a DA DCN Address and TCP-ID. When the DM is received, the Sink TCP on which it was received is recorded (*0x00000000000007365000*). Since the DM received includes a DCN Address, the Discovery Response can be returned without a name-server lookup. + +As before, the response includes the attributes in the DM received, the current attributes being sent on the Tx TCP (*Fmt=1, TCPID=0x00000000000008675309*) related to the Sink TCP, as well as the + +TCP-ID of the Sink TCP (*0x00000000000007365000*). Again, when the discovery response message is received, a unidirectional LC has been identified. + +At this time, it is possible for the discovery response messages to be correlated by each of the ends of the LC to determine whether the bidirectional link has been miswired. Specifically, see Table II.3. + +**Table II.3 – Correlation of discovery response messages** + +| | A \geq B Tx TCPID | A \geq B Rx TCPID | B \geq A DA DCN ID | B \geq A Tx TCPID | B \geq A Rx TCPID | +|------------|---------------------------------------|---------------------------------------|----------------------------------------|---------------------------------------|---------------------------------------| +| A $\geq$ B | 00000000000008675309 | | 2.3.4.1 | 0x12 | 0x42 | +| B $\geq$ A | 00000000000008675309 | 00000000000007365000 | 2.3.4.1 | 0x12 | | + +Since the A $\geq$ B Tx TCPID, the B $\geq$ A DA DCN ID, and B $\geq$ A Tx TCPID fields match, the link is correctly connected. + +The Tx and Rx TCPIDs may now be provided to service capability exchange to determine the capabilities of the link. + +# Appendix III + +## Example of discovery response message using a generalized multi-protocol label signalling-based mechanism + +(This appendix does not form an integral part of this Recommendation.) + +This appendix illustrates one implementation of the LAD as described in this Recommendation, using a generalized multi-protocol label signalling- (GMPLS-) based mechanism. Other possible GMPLS-based implementations are left for further study. + +This example assumes the use of the DA DCN-ID (in-band) DM format (as described in clauses 8.1.2 and 8.1.3) and that the bidirectional control channel between involved parties is established and available for exchanging the discovery response message (as described in clause 11). The bidirectional control channel establishment and maintenance mechanisms and related message exchange are outside of the scope of this appendix. In addition, it is assumed that at a given TCP-ID represents both transmitter and receiver, i.e., the identifier of the TCP where the (received) TCP-ID is received corresponds to the sent TCP-ID. + +In this context, when using J0, the local/remote TCP-ID is equivalent to an interface index, and referenced as an unnumbered LOCAL/REMOTE INTERFACE\_ID, respectively. When using J1/J2, the local/remote TCP-ID is equivalent to an SDH Label (at both end-points) that can be referenced as an unnumbered LOCAL/REMOTE INTERFACE\_ID, respectively. The local/Remote DA DCN-ID corresponds to the IPv4 LOCAL/\_REMOTE\_CONTROL\_ ADDRESS of the local/remote discovery agent, respectively. + +In Figure III.1, summarizing the DM exchange, Node A is referred to as the remote node, and Node B as the local node. + +![Sequence diagram showing discovery message exchange between Node A and Node B.](fc0735d325f0ebd9214171975c68a888_img.jpg) + +The diagram illustrates a sequence of messages between Node A (left) and Node B (right). The sequence is as follows: + +- A green arrow points from Node A to Node B, labeled "In-band discovery message (unnumbered interface ID, control address)". +- A double-headed arrow between Node A and Node B is labeled "Control channel establisheda)". +- A black arrow points from Node B to Node A, labeled "TraceMonitor message (unnum local interface ID, local control address unnum remote interface ID, remote control address, local interface ID)". +- A black arrow points from Node A to Node B, labeled "TraceMonitorAck message". + +a) Process of establishing control channel is outside of the scope of this appendix. + +G.7714.1-Y.1705.1(15)\_FIII.1 + +Sequence diagram showing discovery message exchange between Node A and Node B. + +**Figure III.1 – Summary of discovery messages used in GMPLS based implementations** + +Upon reception of the in-band DM from the DA of node A, an out-of-band discovery response message referred to as the (extended) TraceMonitor message is sent toward the DA of node B over the bidirectional control channel using user datagram protocol/Internet protocol (UDP/IP). This message includes the following information elements (i.e., objects): + + ::= + [] + +where: + + ::= + + type of the trace byte (i.e., J0, J1 or J2) used by the local in-band discovery message + + length in bytes of the + + contains the and the fields + + ::= + + type of the trace byte (i.e., J0, J1 or J2) used by the remote in-band discovery message + + length in bytes of the + + contains the fields + +Upon reception of the TraceMonitor message from the DA of node B, a TraceMonitorAck message is sent to the DA of Node A to acknowledge its reception. + + ::= + +NOTE – Subsequent message exchanges are outside of the scope of this appendix. + +# Appendix IV + +## Layer adjacency discovery implementation examples + +(This appendix does not form an integral part of this Recommendation.) + +The use of discovery is independent of the automatically switched optical network (ASON) control plane realization, which may range from fully centralized to fully distributed. + +- Example 1: External discovery agent controlling trail trace or ECC to implement LAD + +When the discovery agent is located in an external system, an external interface is used by the NE to provision and receive the trail trace message. As an existing text-oriented man-machine language may be reused to provide this interface, the DM should be limited to printable characters defined by [ITU-T T.50]. + +- Example 2: Internal discovery agent controlling trail trace or ECC to implement LAD + +When the discovery agent is located on the NE, the interface used to provision and receive the trail trace message is a local implementation matter. + +# Appendix V + +## In-band message encoding example + +(This appendix does not form an integral part of this Recommendation.) + +Given the message formats defined in clause 8.1, the transmission of the TCP-ID, and discovery agent name or address is accomplished by encoding a sequence of six bits as a printable ITU-T T.50 character. The mapping of the bits to printable ITU-T T.50 characters is defined in [IETF RFC 2045]. Figure V.1 shows the relationship of the octet string to be mapped, and the printable string that results from mapping. + +| | | | | | | | | +|--------------------|----------|----------|----------|----------|----------|----------|-------| +| Octet String (Hex) | 0x11 | 0x23 | 0x45 | 0x67 | 0x8A | 0xBC | ... | +| Binary String | 00010001 | 00100011 | 01000101 | 01100111 | 10001010 | 10111100 | ... | +| 6-bit Decimal | 4 | 18 | 13 | 5 | 25 | 56 | 42 60 | +| Mapped Character | E | S | N | F | Z | 4 | q 8 | + +**Figure V.1 – Relationship between DM octet string and 6-bit mapped characters** + +Once the DM has been mapped, the distinguishing character "+" is prepended yielding the discovery string. + +Some example encoding for the different formats are as follows: + +### Format 1: TCP name format + +Format type: 00012 + Name: 0x1234 5678 ABCD EF00 4321 + The octet string that will be mapped is: 0x1123 4567 8ABC DEF0 0432 1x3 + The printable character string after mapping is: ESNFZ4q83vAEMh64 + The resulting discovery string is: +ESNFZ4q83vAEMh + +### Format 2: DA DCN address format + +Format Type: 00102 + DCN Context ID: 0x0000 (octet string) + DA DCN address: 0x10203040 (octet string) + TCP-ID: 0x12345678 (octet string) + The octet string that will be mapped is: 0x2000 0102 0304 0123 4567 8x3 + The printable character string after mapping is: IAABAgMEASNFZ464 + The resulting discovery string is: +IAABAgMEASNFZ4 + +3 Since 14 characters are available in the trace message, 84 bits are available for carrying the discovery data. This yields 10 octets, with 4 bits remaining. The last octet shown here contains the 4 remaining bits in the high order nibble, causing the lower order nibble to have no meaning as signified by the "x" used here and is not mapped. + +### **Format 3: DA DCN name format** + +| | | +|--------------------------------------------------|--------------------------------------------| +| Format Type: | 0011 2 | +| Name: | 0x9876 5432 10AA | +| TCP-ID: | 0x12345678 (octet string) | +| The octet string that will be mapped is: | 0x3987 6543 210A A123 4567 8x 3 | +| The printable character string after mapping is: | OYdlQyEKoSNFZ4 64 | +| The resulting discovery string is: | +OYdlQyEKoSNFZ4 | + +# Appendix VI + +## Usage of the different discovery mechanisms + +(This appendix does not form an integral part of this Recommendation.) + +## VI.1 Introduction + +This appendix provides clarification of the network scenarios under which the various discovery mechanisms described in the main body of this Recommendation may be utilized, including guidelines for usage of mechanisms and procedures as well as potential associated implications. + +## VI.2 Categories of Type 1 layer adjacency discovery use cases + +The auto-discovery use cases can be subdivided into the categories depicted in Figure VI.1, i.e., pre-service, in-service and out-of-service. Within the context of this Recommendation, the terms pre-service, in-service and out-of-service are defined as follows. + +**pre-service:** The entity that is in a pre-service state is the trail whose associated client LCs have not been allocated. As a consequence, operations will not impact any traffic. Pre-service includes scenarios where discovery is done immediately after a fault has been cleared and before service is considered restored (e.g., during a soaking interval). + +**in-service:** The entity that is in an in-service state is the trail whose associated client LCs have been allocated (one or more). + +**out-of-service:** The entity that is in an out-of-service state is the trail where all allocated client LCs are in a failed or non-usable state. + +This appendix only addresses auto-discovery use cases where the applied auto-discovery mechanism may cause some behavioural problems in the network, i.e., in-service cases. The pre-service and out-of-service use cases, drawn with dotted lines in Figure VI.1, are not further discussed. Moreover, a type 2 LAD is also not considered because the LCs cannot be in service (i.e., carry traffic) at the same time as a type 2 LAD is applied (see [ITU-T G.7714] for the definition of type 1 and type 2 LADs). + +![Figure VI.1 – Categorization of discovery scenarios. A hierarchical diagram showing 'Configuration scenarios' branching into 'Pre-service', 'In-service', and 'Out-of-service'. 'Pre-service' and 'Out-of-service' are dashed boxes with dashed sub-components: 'Both NEs supporting LAD' and 'Only one NE supporting LAD'. 'In-service' is a solid box with solid sub-components: 'Both NEs supporting LAD' and 'Only one NE supporting LAD'. A small code 'G.7714.1-Y1705.1(15)_FVI.1' is at the bottom right.](f1cbfa3fc27f58581615654fec4335d8_img.jpg) + +``` +graph TD; CS[Configuration scenarios] --> PS[Pre-service]; CS --> IS[In-service]; CS --> OS[Out-of-service]; PS -.-> PS1[Both NEs supporting LAD]; PS -.-> PS2[Only one NE supporting LAD]; IS --> IS1[Both NEs supporting LAD]; IS --> IS2[Only one NE supporting LAD]; OS -.-> OS1[Both NEs supporting LAD]; OS -.-> OS2[Only one NE supporting LAD]; style PS stroke-dasharray: 5 5; style OS stroke-dasharray: 5 5; style PS1 stroke-dasharray: 5 5; style PS2 stroke-dasharray: 5 5; style OS1 stroke-dasharray: 5 5; style OS2 stroke-dasharray: 5 5; style IS stroke-width: 2px; style IS1 stroke-width: 2px; style IS2 stroke-width: 2px; +``` + +Figure VI.1 – Categorization of discovery scenarios. A hierarchical diagram showing 'Configuration scenarios' branching into 'Pre-service', 'In-service', and 'Out-of-service'. 'Pre-service' and 'Out-of-service' are dashed boxes with dashed sub-components: 'Both NEs supporting LAD' and 'Only one NE supporting LAD'. 'In-service' is a solid box with solid sub-components: 'Both NEs supporting LAD' and 'Only one NE supporting LAD'. A small code 'G.7714.1-Y1705.1(15)\_FVI.1' is at the bottom right. + +Figure VI.1 – Categorization of discovery scenarios + +## VI.3 Use cases and scenarios + +The various use cases where a type 1 LAD can be applied are described in this clause and guidelines are provided in clause VI.4 that explain how discovery can be accomplished based on the constraints imposed by the different scenarios. As specified in the main body of this Recommendation, it is assumed that there is always congruency between the signal being used for LAD and the entity being discovered. In describing the various scenarios, two cases are broadly distinguished: + +- where all the NEs are auto-discovery capable; and + +b) where some of the NEs within the network are not auto-discovery capable. + +### VI.3.1 All NEs are auto-discovery capable (ubiquitous deployment) + +Ubiquitous deployment means that all NEs are auto-discovery capable and it is assumed that all involved NEs support LAD as defined in [ITU-T G.7714] and in the main body of this Recommendation. For this subset of cases, either trail-trace-based or ECC-based DMs can be used, provided all the NEs agree on a specific common mechanism. + +### VI.3.2 All NEs are not auto-discovery capable + +If some of the NEs within the network are assumed to be unable to understand the auto-DMs (e.g., legacy equipment). We consider two scenario classes for the case where auto-discovery is being performed at a particular layer between the two NEs that represent the endpoints of that layer: + +- where both NEs are LAD-capable; +- where one of the two NEs does not support LAD. + +##### VI.3.2.1 Auto-discovery between LAD-capable NEs + +As described in [ITU-T G.7714], the LAD process requires that two NEs that are performing LAD must be immediate neighbours with respect to the layer where discovery is taking place (e.g., for SDH at RS, MS, HO or LO path layer). It is not possible, for example, to perform LAD based on using the section trail trace (J0), RS DCCs, or MS DCCs when there is a NE between the two LAD-capable NEs that does not support LAD and terminates the RS and MS. Therefore, it is only possible to perform LAD at the path layer for such a configuration and the HOVC path-trace (J1)-based discovery method may have to be used. This is illustrated in Figure VI.2. It is also possible for the network management system (NMS) to run the HO path layer LAD process by proxy for the NEs, as depicted in Figure VI.3. + +![Figure VI.2: Immediate discovery-capable neighbours at HO path layer – LAD done by NEs. The diagram shows two discovery-capable NEs connected via a non-discovery-capable NE. The top part shows the HO path LAD message exchange over STM-4 links. The bottom part shows the HO path LAD process at the HO path layer, with J1 path traces and S4, MS, RS, and DCC layers.](1ad662a678c4f002de911d403f00de8e_img.jpg) + +The diagram illustrates the network configuration for HO path layer LAD. At the top, two 'Discovery-capable NE' units, each containing a 'LAD' circle and an 'NE' box, are connected via a central 'Non-discovery-capable NE' box. The connections are labeled 'STM-4'. A dashed double-headed arrow between the discovery-capable NEs is labeled 'HO path LAD message exchange'. Below this, a detailed view shows three nodes. Each node has a top section with a 'J1' label and an 'S4' oval. The middle section contains 'MS' (Multiplex Section) and 'RS' (Regenerator Section) blocks, with 'MS-DCC' and 'RS-DCC' labels. The bottom section shows 'J0' labels. A blue double-headed arrow labeled 'HO path LAD' spans across the top of the three nodes. The central node's S4 oval contains dashed boxes representing internal components. + +Figure VI.2: Immediate discovery-capable neighbours at HO path layer – LAD done by NEs. The diagram shows two discovery-capable NEs connected via a non-discovery-capable NE. The top part shows the HO path LAD message exchange over STM-4 links. The bottom part shows the HO path LAD process at the HO path layer, with J1 path traces and S4, MS, RS, and DCC layers. + +**Figure VI.2 – Immediate discovery-capable neighbours at HO path layer – LAD done by NEs** + +![Diagram illustrating immediate discovery-capable neighbours at the HO path layer with LAD done by NMS. The diagram shows three Network Elements (NEs) connected in a line via STM-4 links. The left and right NEs are 'Discovery-capable NE', while the middle one is a 'Non-discovery-capable NE'. Above the NEs, an NMS box contains two 'LAD' circles connected by a dashed double-headed arrow. Dashed lines connect each NE to the NMS. A dashed oval labeled 'HO path LAD message exchange' spans between the left and right NEs, passing through the NMS. Below the NEs, a detailed view shows the protocol stack: J1 (antenna), S4 (circle), MS (MS-DCC), RS (RS-DCC), and J0 (bottom line). The left and right stacks are connected to the middle stack via MS-DCC and RS-DCC lines. A thick blue double-headed arrow labeled 'HO path LAD' connects the J1 points of the left and right stacks. The text 'G.7714.1-Y.1705.1(15)_FVI.3' is in the bottom right corner.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +Diagram illustrating immediate discovery-capable neighbours at the HO path layer with LAD done by NMS. The diagram shows three Network Elements (NEs) connected in a line via STM-4 links. The left and right NEs are 'Discovery-capable NE', while the middle one is a 'Non-discovery-capable NE'. Above the NEs, an NMS box contains two 'LAD' circles connected by a dashed double-headed arrow. Dashed lines connect each NE to the NMS. A dashed oval labeled 'HO path LAD message exchange' spans between the left and right NEs, passing through the NMS. Below the NEs, a detailed view shows the protocol stack: J1 (antenna), S4 (circle), MS (MS-DCC), RS (RS-DCC), and J0 (bottom line). The left and right stacks are connected to the middle stack via MS-DCC and RS-DCC lines. A thick blue double-headed arrow labeled 'HO path LAD' connects the J1 points of the left and right stacks. The text 'G.7714.1-Y.1705.1(15)\_FVI.3' is in the bottom right corner. + +**Figure VI.3 – Immediate discovery-capable neighbours at HO path layer – LAD done by NMS** + +##### VI.3.2.2 Auto-discovery between a LAD-capable NE and a non-LAD-capable NE + +In this case, it is assumed that the non-LAD-capable NE terminates the layer being discovered (see Figure VI.4). In such a case, LAD cannot be performed at that specific layer, since the DMs sent by the LAD-capable NE are not understood by the non-LAD-capable NE. In such a scenario, it is important that the non-LAD-capable NE does not generate alarms and, more important, not perform consequent actions that could unnecessarily disrupt service. One possible means for the network operator to avoid such alarms and consequent actions is to disable the transmission of DMs at the LAD-capable NE or to obey the guidelines described in clause VI.4. + +![Figure VI.4: Discovery-capable NE trying to discover a non-discovery-capable NE. The diagram is split into two parts. The top part shows a 'Discovery-capable NE' containing a 'LAD' circle and an 'NE' box, connected via a dashed line labeled 'MS LAD message exchange' and a solid line labeled 'STM-4' to a 'Non-discovery-capable NE' containing an 'NE' box. The bottom part shows a more detailed view of the layers: an 'S4' oval at the top with 'J1' and 'MS-DCC' labels; a triangle labeled 'MS' below it with 'MS LAD' (blue arrow) and 'RS-DCC' labels; a triangle labeled 'RS' below that with 'J0' labels; and a bottom line. The same layers are shown on the right side, but the 'MS LAD' blue arrow is missing, indicating no discovery message exchange.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +Figure VI.4: Discovery-capable NE trying to discover a non-discovery-capable NE. The diagram is split into two parts. The top part shows a 'Discovery-capable NE' containing a 'LAD' circle and an 'NE' box, connected via a dashed line labeled 'MS LAD message exchange' and a solid line labeled 'STM-4' to a 'Non-discovery-capable NE' containing an 'NE' box. The bottom part shows a more detailed view of the layers: an 'S4' oval at the top with 'J1' and 'MS-DCC' labels; a triangle labeled 'MS' below it with 'MS LAD' (blue arrow) and 'RS-DCC' labels; a triangle labeled 'RS' below that with 'J0' labels; and a bottom line. The same layers are shown on the right side, but the 'MS LAD' blue arrow is missing, indicating no discovery message exchange. + +**Figure VI.4 – Discovery-capable NE trying to discover a non-discovery-capable NE** + +## VI.4 Guidelines for mechanisms and procedures + +This clause provides guidelines on the usage of the trail trace (J0, J1 and J2) and ECC (MS DCC or RS DCC) mechanisms for LAD for the various use cases and scenarios described in clause VI.3. + +#### VI.4.1 ECC-based LAD + +Auto-discovery using the DCC is a viable option when the DCC is available on the synchronous transport module-n (STM-n) interface that needs to be discovered. The DCC provides a packet-based interface; its use for LAD is not affected by the service state (in-service, out-of-service, pre-service) of the given STM-n interface it is associated with. The LAD process making use of the DCC does not have any impact on the traffic on the STM-n interface. However, there are a number of use cases where the DCC may not be sufficient for LAD, based on DCC availability given the DCN deployment scenarios described in clause IV.4.1.1. + +##### VI.4.1.1 DCN deployment scenarios impacting the availability of DCCs + +There are two scenarios which affect the deployment of DCC-based LAD messages. + +- a) No DCC connectivity [e.g., central office (CO) LAN supporting the DCN]. + +In this scenario, there is no DCC connectivity between the add-drop multiplexers (ADMs) and the digital cross connect (DXC) in the CO. Instead, as shown in Figure VI.5, the CO LAN is used to carry the management communication between the NEs in the CO. Although there is connectivity (e.g., STM-n) between the ADMs and the DXC, the management communication does not follow the same topology as these optical connections that contain the DCCs. The DXC could be used to interconnect low-speed optical interfaces between ADMs within a CO – and therefore the DCCs on these low-speed optical interfaces are not available for auto-discovery. + +![Diagram of a central office with disabled DCC connectivity. A central box labeled 'DXC' is connected to a 'Central office LAN' at the top. On either side of the DXC are 'ADM' (Add-Drop Multiplexer) units. Arrows pointing to the interfaces between the ADMs and the DXC are labeled 'DCCs disabled'. The diagram is labeled 'G.7714.1-Y.1705.1(15)_FVI.5'.](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg) + +Diagram of a central office with disabled DCC connectivity. A central box labeled 'DXC' is connected to a 'Central office LAN' at the top. On either side of the DXC are 'ADM' (Add-Drop Multiplexer) units. Arrows pointing to the interfaces between the ADMs and the DXC are labeled 'DCCs disabled'. The diagram is labeled 'G.7714.1-Y.1705.1(15)\_FVI.5'. + +**Figure VI.5 – Central office with disabled DCC connectivity** + +- b) Limited DCC availability or DCCs not enabled on all parallel interfaces between two NEs. +- In this scenario, as depicted in Figure VI.6, there may be limited or no DCC availability for management communication between NEs – e.g., due to disabling of DCCs, or limited DCC resources. This could occur between multiple carriers, at a customer-to-carrier interface, or where only out-of-band connectivity is available between the NEs – and therefore the DCC is not available for auto-discovery. It is also possible that there are multiple parallel optical interfaces connecting the two NEs. However, the DCCs on only one link or a small subset of links may be enabled. This may be the case for several administrative reasons, e.g.: +- DCC processing not supported for all interfaces; + - configuration decision (e.g., in case of multiple parallel links, the DCCs are only enabled on some of them, since the capacity of a single DCC may be sufficient for management communication between the two NEs); + - policy decisions in the case of connectivity of NEs between different administrative domains. + +In all these cases, it may not be possible to perform LAD on every link using DCC, because some of the links may not have the DCC enabled. + +![Diagram of a central office with DCC enabled on only one link or using an out-of-band DCN. Two 'NE' (Network Element) boxes are connected by multiple parallel lines. The top line is labeled 'Out-of-band DCN'. An arrow pointing to the top line is labeled 'DCC enabled'. Arrows pointing to the lower parallel lines are labeled 'DCC disabled'. The diagram is labeled 'G.7714.1-Y.1705.1(15)_FVI.6'.](f5deee2f3301ee351c4008283ffafbb3_img.jpg) + +Diagram of a central office with DCC enabled on only one link or using an out-of-band DCN. Two 'NE' (Network Element) boxes are connected by multiple parallel lines. The top line is labeled 'Out-of-band DCN'. An arrow pointing to the top line is labeled 'DCC enabled'. Arrows pointing to the lower parallel lines are labeled 'DCC disabled'. The diagram is labeled 'G.7714.1-Y.1705.1(15)\_FVI.6'. + +**Figure VI.6 – Central office with DCC enabled on only one link or using an out-of-band DCN** + +#### VI.4.2 Trail-trace-based LAD + +##### Case A (using J0, J1 and J2 bytes) + +The trail-trace bytes can be utilized for Type 1 LAD, which allows the client layer LCs to be inferred from the discovered server layer trail as depicted in Figure 1. Depending on the configuration of the TT functions involved in the LAD process, some behavioural issues could arise. In particular, traffic impact has to be avoided while the interfaces are in the in-service state and are carrying traffic. These scenarios where such behavioural issues might occur are addressed in this clause and are discussed in detail in the following. Moreover, application and configuration guidelines are provided in order to avoid traffic impacts. + +##### Case B (using the TTI field of the TCM sublayer 6) + +If intermediate equipment such as wavelength division multiplexing (WDM) transponders terminate the OTU layer, the TTI field of TCM sublayer 6 is used for auto-discovery in OTN networks. This scenario is illustrated in Figure VI.7. + +![Diagram illustrating the OTN architecture for auto-discovery using the TTI field of the TCM sublayer 6. The diagram shows two end systems, ODU-XC A and ODU-XC B, connected via two intermediate WDM devices, WDM-Device C and WDM-Device D. ODU-XC A and ODU-XC B each contain a Discovery agent (A and B respectively) connected to an ODUk layer. The ODUk layer is connected to two ODUkT layers (one yellow, one green in A; one green, one purple in B). The ODUkT layers are connected to two OTUk layers. The OTUk layers are connected to the WDM-Device C and WDM-Device D. Each WDM device contains two OTUk layers connected to an OCh layer, which is connected to an OMS layer, which is connected to an OTS layer. The OTS layers are connected to each other. The Discovery agents send discovery messages (Disc. Msg) carried in the OTUkT TTI field. The TTI field is shown being passed through the ODUkT layers and the OTUk layers. The WDM devices are shown as terminating the OTU layer and passing the OCh layer. The diagram is labeled G.7714.1-Y.1705.1(15)_FVI.7.](95e259e8cb3519025066052af263f8c0_img.jpg) + +Diagram illustrating the OTN architecture for auto-discovery using the TTI field of the TCM sublayer 6. The diagram shows two end systems, ODU-XC A and ODU-XC B, connected via two intermediate WDM devices, WDM-Device C and WDM-Device D. ODU-XC A and ODU-XC B each contain a Discovery agent (A and B respectively) connected to an ODUk layer. The ODUk layer is connected to two ODUkT layers (one yellow, one green in A; one green, one purple in B). The ODUkT layers are connected to two OTUk layers. The OTUk layers are connected to the WDM-Device C and WDM-Device D. Each WDM device contains two OTUk layers connected to an OCh layer, which is connected to an OMS layer, which is connected to an OTS layer. The OTS layers are connected to each other. The Discovery agents send discovery messages (Disc. Msg) carried in the OTUkT TTI field. The TTI field is shown being passed through the ODUkT layers and the OTUk layers. The WDM devices are shown as terminating the OTU layer and passing the OCh layer. The diagram is labeled G.7714.1-Y.1705.1(15)\_FVI.7. + +**Figure VI.7 – Example of ODUkT TTI (SAPI sub-field)-based LAD for OTN with WDM equipment** + +##### VI.4.2.1 Pre-service and out-of-service cases + +The use of the trail-trace bytes for LAD does not cause any behavioural issues as long as the interface is in a pre-service or out-of-service state because no traffic is being carried over it. + +##### VI.4.2.2 In-service cases + +It should be noted that discovery enabling or disabling capability is provided at each link end at a specific layer independent of the remote end. Note that the discovery process is only permitted to change (provision) the TTI when the discovery process is enabled. + +Usage of the trail-trace bytes as defined in [b-ITU-T G.707] allow transmission and reception of APIs so that the receiving terminal can verify its continued connection to the intended transmitter. The formats used for LAD are different to formats commonly used for pre-existing applications. It is expected that new equipment should be able to recognize this usage. In order to avoid undesired trace identifier mismatch (TIM) alarms for some legacy equipment, the discovery-capable NE should not change the TTI (i.e., should disable auto-discovery) at its trail end when there is a non-discovery capable NE at the other end. Discovery should also be disabled when the trail includes monitors that are monitoring the TTI and are unable to distinguish DMs. + +Note that the discovery process could be performed in a management system, thereby making an NE discovery capable. + +For some existing equipment, use of the trail-trace bytes for discovery may raise alarms, and if the consequent action [alarm indication signal (AIS) insertion] is not disabled, may cause traffic loss. Therefore, TT points that allow trail-trace-based discovery should set TIMAISdis=true to prevent the insertion of an AIS when the TTI does not match. In national networks where TIMAISdis is required to be always false (see [b-ITU-T G.806]), trail-trace-based discovery should not be performed. + +If dTIM detection is enabled, the LAD process can use the MI\_cTIM as a notification that the trail trace has changed (MI\_AcTI). + +##### **Non-intrusive monitoring** + +Non-intrusive monitor functions (see [b-ITU-T G.783]) may observe the trail trace. If the non-intrusive monitor function is not aware of the use of trail-trace for discovery, unexpected changes in TTI will be observed. + +#### **VI.4.3 Inter-carrier, user-provider implications** + +The LAD process can be enabled or disabled on each interface. This allows the network operators to configure the interfaces according to their policy. + +# Bibliography + +- [b-ITU-T G.707] Recommendation ITU-T G.707/Y.1322 (2007), *Network node interface for the synchronous digital hierarchy (SDH)*. +- [b-ITU-T G.783] Recommendation ITU-T G.783 (2006), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks*. +- [b-ITU-T G.784] Recommendation ITU-T G.784 (2008), *Management aspects of Synchronous digital hierarchy (SDH) transport network elements*. +- [b-ITU-T G.806] Recommendation ITU-T G.806 (2012), *Characteristics of transport equipment – Description methodology and generic functionality*. +- [b-ISO 3166] International Standard 3166 (all parts), *Codes for the representation of names of countries and their subdivisions*. +- [b-IETF RFC 1661] IETF RFC 1661 (1994), *The point-to-point protocol*. +- [b-IETF RFC 1930] IETF RFC 1930 (1996), *Guidelines for creation, selection, and registration of an Autonomous System (AS)*. + + + +## ITU-T Y-SERIES RECOMMENDATIONS + +## GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES + +| | | +|--------------------------------------------------------------------|----------------------| +| GLOBAL INFORMATION INFRASTRUCTURE | | +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | +| INTERNET PROTOCOL ASPECTS | | +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | +| IPTV over NGN | Y.1900–Y.1999 | +| NEXT GENERATION NETWORKS | | +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Enhancements to NGN | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Network control architectures and protocols | Y.2500–Y.2599 | +| Packet-based Networks | Y.2600–Y.2699 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | +| Carrier grade open environment | Y.2900–Y.2999 | +| FUTURE NETWORKS | Y.3000–Y.3499 | +| CLOUD COMPUTING | Y.3500–Y.3999 | +| INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES | | +| General | Y.4000–Y.4049 | +| Definitions and terminologies | Y.4050–Y.4099 | +| Requirements and use cases | Y.4100–Y.4249 | +| Infrastructure, connectivity and networks | Y.4250–Y.4399 | +| Frameworks, architectures and protocols | Y.4400–Y.4549 | +| Services, applications, computation and data processing | Y.4550–Y.4699 | +| Management, control and performance | Y.4700–Y.4799 | +| Identification and security | Y.4800–Y.4899 | +| Evaluation and assessment | Y.4900–Y.4999 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.7719-202106-I_PDF-E/raw.md b/marked/G/T-REC-G.7719-202106-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..cc2be6d4538a480bab16776ac2517b3e6da7c2aa --- /dev/null +++ b/marked/G/T-REC-G.7719-202106-I_PDF-E/raw.md @@ -0,0 +1,654 @@ + + +**ITU-T** + +**G.7719** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(06/2021) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Data over Transport – Generic aspects – Transport +network control aspects + +--- + +**Management information model for +management-control components and functions** + +Recommendation ITU-T G.7719 + +# ITU-T G-SERIES RECOMMENDATIONS + +## TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| General | G.7000–G.7099 | +| Transport network control aspects | G.7700–G.7799 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +For further details, please refer to the list of ITU-T Recommendations. + +## Recommendation ITU-T G.7719 + +# Management information model for management-control components and functions + +## Summary + +Recommendation ITU-T G.7719 establishes a protocol-neutral information model to manage components that provide management and control (MC) functions for transport network resources. Management requirements for such MC components are specified in Recommendation ITU-T G.7718 to support the MC functions specified in Recommendations ITU-T G.7701, ITU-T G.7702 and ITU-T G.7703. The information model established in Recommendation ITU-T G.7719 is specified using the Unified Modeling Language (UML). + +This Recommendation includes an electronic attachment with the UML model developed for the Recommendation. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.7718.1/Y.1709.1 | 2006-12-14 | 15 | 11.1002/1000/9002 | +| 2.0 | ITU-T G.7719 | 2021-06-29 | 15 | 11.1002/1000/14711 | + +## Keywords + +ASON, component, control, control domain, controller, management, protocol-neutral information model, SDN, UML, virtual network. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2021 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 5.1 Information modelling conventions ..... | 3 | +| 6 Management requirements for management-control components and functions..... | 3 | +| 7 Management information model for management and control ..... | 4 | +| 7.1 Representation of a management and control system ..... | 4 | +| 7.2 Representation of management-control components ..... | 5 | +| 7.3 Representation of contexts ..... | 7 | +| 7.4 Interworking of client, server and administrative contexts ..... | 10 | +| 7.5 Management-control component attributes..... | 11 | +| 7.6 Context attributes..... | 13 | +| 8 UML model file ..... | 15 | +| Bibliography..... | 16 | + +Electronic attachment : The Papyrus UML developed for the Recommendation. + + + +# Management information model for management-control components and functions + +# 1 Scope + +This Recommendation1 establishes a protocol-neutral information model to manage the components that provide management and control (MC) functions for transport network resources. The concept whereby MC functions are considered to be a continuum is known as the management-control continuum (MCC); i.e., it expresses the view that MC functions are essentially the same and thus can be grouped into one set. The management requirements for such MC components are specified in [ITU-T G.7718] to support the MC functions specified in [ITU-T G.7701], [ITU-T G.7702], and [ITU-T G.7703]. + +The information model established in this Recommendation is interface protocol neutral and specified using the Unified Modeling Language (UML). The information model is derived through pruning and refactoring the ITU-T G.7711 core information model, extended with MC function specific characteristics. The information model can be used to derive the data model to be used in the interface to the administrative context or to client contexts. The translation of the information model into the data model of a specific protocol, such as NETCONF/YANG, is a decision of protocol-specific modelling design and lies outside the scope of this Recommendation. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.798] Recommendation ITU-T G.798 (2017), *Characteristics of optical transport network hierarchy equipment functional blocks*. +- [ITU-T G.874] Recommendation ITU-T G.874 (2017), *Management aspects of optical transport network elements*. +- [ITU-T G.7701] Recommendation ITU-T G.7701 (2016), *Common control aspects*. +- [ITU-T G.7702] Recommendation ITU-T G.7702 (2018), *Architecture for SDN control of transport networks*. +- [ITU-T G.7703] Recommendation ITU-T G.7703 (2021), *Architecture for the automatically switched optical network*. +- [ITU-T G.7711] Recommendation ITU-T G.7711/Y.1702 (2018), *Generic protocol-neutral management information model for transport resources*. +- [ITU-T G.7718] Recommendation ITU-T G.7718/Y.1709 (2020), *Framework for the management of management-control components and functions*. + +--- + +1 This Recommendation includes an electronic attachment with the UML developed for the Recommendation. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **component**: [ITU-T G.7701]. +- 3.1.2 **connection controller (CC)**: [ITU-T G.7701]. +- 3.1.3 **discovery agent (DA)**: [ITU-T G.7701]. +- 3.1.4 **link resource manager (LRM)**: [ITU-T G.7701]. +- 3.1.5 **network call controller (NCC)**: [ITU-T G.7701]. +- 3.1.6 **protocol controller (PC)**: [ITU-T G.7701]. +- 3.1.7 **routing controller (RC)**: [ITU-T G.7701]. +- 3.1.8 **subnetwork point (SNP)**: [ITU-T G.7701]. +- 3.1.9 **subnetwork point pool (SNPP)**: [ITU-T G.7701]. +- 3.1.10 **termination and adaptation performer (TAP)**: [ITU-T G.7701]. +- 3.1.11 **virtual network (VN)**: [ITU-T G.7701]. + +## 3.2 Terms defined in this Recommendation + +None. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-----|-------------------------------| +| BRI | Boundary Resource Identifier | +| CC | Connection Controller | +| CPI | Control Plane Interface | +| DA | Discovery Agent | +| DCN | Data Communication Network | +| EMS | Element Management System | +| FP | Forwarding Point | +| ID | Identifier | +| LRM | Link Resource Manager | +| MC | Management and Control | +| MCC | Management-Control Continuum | +| MCS | Management and Control System | +| NCC | Network Call Controller | +| NE | Network Element | +| NMS | Network Management System | +| OTN | Optical Transport Network | + +| | | +|------|--------------------------------------| +| PC | Protocol Controller | +| PNG | Portable Network Graphic | +| RC | Routing Controller | +| SCN | Signalling Communication Network | +| SDN | Software-Defined Networking | +| SNP | Subnetwork Point | +| SNPP | Subnetwork Point Pool | +| TAP | Termination and Adaptation Performer | +| UML | Unified Modeling Language | +| VN | Virtual Network | + +# 5 Conventions + +## 5.1 Information modelling conventions + +### 5.1.1 UML modelling conventions + +See clause 5.1 of [ITU-T G.7711]. + +### 5.1.2 Model artefact lifecycle stereotype conventions + +See clause 5.2 of [ITU-T G.7711]. + +### 5.1.3 Forwarding entity terminology conventions + +See clause 5.3 of [ITU-T G.7711]. + +### 5.1.4 Conditional package conventions + +See clause 5.4 of [ITU-T G.7711]. + +### 5.1.5 Pictorial diagram conventions + +See clause 5.5 of [ITU-T G.7711]. + +# 6 Management requirements for management-control components and functions + +The management of MC components and functions is part of the transport network MC as shown in Figure 6-2 of [ITU-T G.7701]. MC components themselves need to be managed or controlled to fulfil their intended functionality. Their requirements for management include that of faults, configuration (including lifecycle), accounts, performance and security. + +[ITU-T G.7718] specifies the management requirements of MC components or functions established in [ITU-T G.7701], [ITU-T G.7702] and [ITU-T G.7703]. The management requirements of components in an MC system are established in a similar way to the relationship between a transport technology functional block model (e.g., [ITU-T G.798] for optical transport network (OTN) functional blocks) and its management requirements (e.g., [ITU-T G.874] for OTN management requirements). + +MC components are modelled by pruning and refactoring model artefacts such as ControlConstruct, ConstraintDomain, ExposureContext and ControlPort that are specified in Annex H of + +[ITU-T G.7711]. These objects need to be managed, including creation or deletion, for lifecycle management whenever a new client controller is connected to or disconnected from a server controller via the ControlPort. + +Detailed management requirements of the MC components and functions are specified in clause 8 of [ITU-T G.7718]. Information models representing each control component and transport service are established in this Recommendation. + +# 7 Management information model for management and control + +Clause 6.8 and Annex H of [ITU-T G.7711] establish the general model suitable for representation of the capabilities that control the network and for representation of the relationship to the model of the network from the control perspective. This general control model can be used to model functional groupings, e.g., a software-defined networking (SDN) controller, giving a consistent view of the different elements in the control domain. The capability of the model is generalized so that it can handle all aspects of the management and control system (MCS). + +## 7.1 Representation of a management and control system + +In Figure 7-1, the control port, control construct and constraint domain represent the interface, functions and boundary respectively of an MCS managed by the administration role. The MCS could be an SDN controller, an element management system/network management system (EMS/NMS) or the equipment management function block of a network element (NE). Through the control constructs and control ports, the administration role can configure the MCS on initialization. If more than one server context is present in the associated constraint domain, the control constructs will also manage the links between the subnetworks in different server contexts. + +![Diagram of Figure 7-1: Control construct for SDN controller or EMS/NMS or network element. The diagram shows an 'Administration' box at the top connected via a dashed line labeled 'Logical association' to a 'Control construct' box inside a large blue box labeled 'Constraint domain (Controller or EMS/NMS or NE)'. A 'Control port' is indicated by an arrow pointing to the interface between the Administration and the Control construct.](053f1077d592e6622cd21dc4bb4cb366_img.jpg) + +The diagram illustrates the control construct for an SDN controller, EMS/NMS, or network element. At the top, an orange box labeled 'Administration' is shown. Below it, a dashed vertical line labeled 'Logical association' connects to another orange box labeled 'Control construct'. This 'Control construct' is located inside a large light blue rectangular area labeled 'Constraint domain (Controller or EMS/NMS or NE)'. A blue arrow labeled 'Control port' points from the 'Administration' box to the interface between the 'Administration' and the 'Control construct' box. The diagram is labeled 'G.7719(21)\_F7-1' in the bottom right corner. + +Diagram of Figure 7-1: Control construct for SDN controller or EMS/NMS or network element. The diagram shows an 'Administration' box at the top connected via a dashed line labeled 'Logical association' to a 'Control construct' box inside a large blue box labeled 'Constraint domain (Controller or EMS/NMS or NE)'. A 'Control port' is indicated by an arrow pointing to the interface between the Administration and the Control construct. + +**Figure 7-1 – Control construct for SDN controller or EMS/NMS or network element** + +In Figure 7-2, multiple constraint domains, control constructs and control ports are used to represent the contexts of a client, server and administration inside an SDN controller, which interacts with the other SDN controllers at adjacent levels. + +![Figure 7-2 – ControlConstruct for SDN controller. This diagram illustrates the hierarchical structure of SDN controllers. At the top is an 'Administration' box. Below it, a large blue box represents 'Controller n'. Inside this box, there's a 'Control construct Mn' box connected to 'Administration' via a dashed line labeled 'Logical association'. 'Control construct Mn' is also connected to a 'Control port' box. The 'Control port' box is connected to 'Control construct Cn (1)' box. 'Control construct Cn (1)' is connected to a 'Resources available to client' box. 'Control construct Cn (1)' is also connected to a 'Control construct Sn (1)' box. 'Control construct Sn (1)' is connected to a 'Resources provided by server' box. 'Control construct Sn (1)' is also connected to 'Control construct Cn-1 (1)' box. 'Control construct Cn-1 (1)' is connected to a 'Resources available to client' box. 'Control construct Cn-1 (1)' is also connected to a 'Control construct Sn+1 (1)' box. 'Control construct Sn+1 (1)' is connected to a 'Resources provided by server' box. Various 'Constraint domain' labels are present: 'Constraint domain (Administrative context)' pointing to 'Administration', 'Constraint domain (Server context in client controller)' pointing to 'Resources provided by server' (top), 'Constraint domain (Client context)' pointing to 'Resources available to client' (middle), 'Constraint domain (Server context)' pointing to 'Resources provided by server' (middle), 'Constraint domain (Controller n)' pointing to the blue box, 'Constraint domain (Client context in server controller)' pointing to 'Resources available to client' (bottom), and 'Constraint domain (Server context)' pointing to 'Resources provided by server' (bottom). Vertical double-headed arrows on the right indicate 'Client Server' relationships between 'Controller n+1' and 'Controller n', and between 'Controller n' and 'Controller n-1'. A label 'G.7719(21)_F7-2' is at the bottom right.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Figure 7-2 – ControlConstruct for SDN controller. This diagram illustrates the hierarchical structure of SDN controllers. At the top is an 'Administration' box. Below it, a large blue box represents 'Controller n'. Inside this box, there's a 'Control construct Mn' box connected to 'Administration' via a dashed line labeled 'Logical association'. 'Control construct Mn' is also connected to a 'Control port' box. The 'Control port' box is connected to 'Control construct Cn (1)' box. 'Control construct Cn (1)' is connected to a 'Resources available to client' box. 'Control construct Cn (1)' is also connected to a 'Control construct Sn (1)' box. 'Control construct Sn (1)' is connected to a 'Resources provided by server' box. 'Control construct Sn (1)' is also connected to 'Control construct Cn-1 (1)' box. 'Control construct Cn-1 (1)' is connected to a 'Resources available to client' box. 'Control construct Cn-1 (1)' is also connected to a 'Control construct Sn+1 (1)' box. 'Control construct Sn+1 (1)' is connected to a 'Resources provided by server' box. Various 'Constraint domain' labels are present: 'Constraint domain (Administrative context)' pointing to 'Administration', 'Constraint domain (Server context in client controller)' pointing to 'Resources provided by server' (top), 'Constraint domain (Client context)' pointing to 'Resources available to client' (middle), 'Constraint domain (Server context)' pointing to 'Resources provided by server' (middle), 'Constraint domain (Controller n)' pointing to the blue box, 'Constraint domain (Client context in server controller)' pointing to 'Resources available to client' (bottom), and 'Constraint domain (Server context)' pointing to 'Resources provided by server' (bottom). Vertical double-headed arrows on the right indicate 'Client Server' relationships between 'Controller n+1' and 'Controller n', and between 'Controller n' and 'Controller n-1'. A label 'G.7719(21)\_F7-2' is at the bottom right. + +Figure 7-2 – ControlConstruct for SDN controller (Figure 3-14 of [b-ONF TR-512]) + +## 7.2 Representation of management-control components + +### 7.2.1 Generic control model + +Annex H of [ITU-T G.7711] provides the general control model. Figure 7-3 summarizes the control model. + +The ConstraintDomain (CD) object class represents the boundary of a view that can represent the network resource or network control functions within its scope. An SDN controller can be represented by a ConstraintDomain object instance. Network resources and control functions inside a ConstraintDomain instance can be exposed to the client via a control port and then viewed by the client through the control plane interface (CPI). + +The ExposureContext (EC) object class sets the rules and requirements for how the ConstraintDomain is to be exposed and can be accessed. The same resource can be exposed to different customers with different rules. The ExposureContext object class has an attribute pointing to a ConstraintDomain that determines the view of (i.e., groups of) the control functions or network resources to be exposed for management purposes. The ExposureContext has its lifecycle and different rules when it is exposed to different customers. + +The ProcessingConstruct (PC) object class represents generalized processing functionality; it can be used to represent control processes. + +The ControlConstruct (CtrlC) object class is a specialized PC. It represents the control capability and functionality. A ControlConstruct processes information to control other functions. + +The ControlPort object class represents the port used for connections between controllers. Network resources and functions are exposed to client controllers via the ControlPort. + + + +![Figure 7-4: Pruning and refactoring for control components. This UML class diagram shows the hierarchy and associations for control components. At the top is the 'CoreModel:ProcessingConstructModel:ObjectClasses' object class, which contains 'ConstraintDomain'. Below it are 'CoreModel:GeneralControllerModel:ObjectClasses' (with 'ControlConstruct') and 'CoreModel:GeneralControlModel:ObjectClasses' (with 'ControlPort'). Further down are 'Itu-mc-mgmt:ObjectClasses' for 'HuMcComponent', 'PcComponent', 'LmComponent', 'TapComponent', 'DcComponent', 'RcComponent', 'NcComponent', 'CoComponent', and 'NotificationComponent'. Associations include 'CdConstrainsHuMcComponent', 'HuMcComponentRealizesControlConstruct', 'PcComponentRealizesHuMcComponent', 'DcComponentRealizesProcessingConstruct', 'PcCommunicatesWithOtherPc', 'PcAssociatedWithControlPort', 'DcComponentAssociatedWithPc', 'RcComponentAssociatedWithPc', 'NcAssociatedWithPc', 'CoAssociatedWithPc', and 'DaAssociatedWithPc'.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Figure 7-4: Pruning and refactoring for control components. This UML class diagram shows the hierarchy and associations for control components. At the top is the 'CoreModel:ProcessingConstructModel:ObjectClasses' object class, which contains 'ConstraintDomain'. Below it are 'CoreModel:GeneralControllerModel:ObjectClasses' (with 'ControlConstruct') and 'CoreModel:GeneralControlModel:ObjectClasses' (with 'ControlPort'). Further down are 'Itu-mc-mgmt:ObjectClasses' for 'HuMcComponent', 'PcComponent', 'LmComponent', 'TapComponent', 'DcComponent', 'RcComponent', 'NcComponent', 'CoComponent', and 'NotificationComponent'. Associations include 'CdConstrainsHuMcComponent', 'HuMcComponentRealizesControlConstruct', 'PcComponentRealizesHuMcComponent', 'DcComponentRealizesProcessingConstruct', 'PcCommunicatesWithOtherPc', 'PcAssociatedWithControlPort', 'DcComponentAssociatedWithPc', 'RcComponentAssociatedWithPc', 'NcAssociatedWithPc', 'CoAssociatedWithPc', and 'DaAssociatedWithPc'. + +Figure 7-4 – Pruning and refactoring for control components + +![Figure 7-5: Detail view of control components. This diagram provides a detailed view of the control components, showing their attributes and associations. The 'HuMcComponent' has attributes like 'controlPort: ControlPort [?]' and 'viewMapping: [1]'. Other components like 'PcComponent', 'LmComponent', 'TapComponent', 'DcComponent', 'RcComponent', 'NcComponent', 'CoComponent', and 'NotificationComponent' also have specific attributes. Associations between these components are shown, such as 'NcAssociatedWithPc', 'DcAssociatedWithNc', 'CoAssociatedWithPc', 'PcAssociatedWithPc', and 'DaAssociatedWithPc'.](eefe19c5e14dc4d6c316b7f7fbb7d7d7_img.jpg) + +Figure 7-5: Detail view of control components. This diagram provides a detailed view of the control components, showing their attributes and associations. The 'HuMcComponent' has attributes like 'controlPort: ControlPort [?]' and 'viewMapping: [1]'. Other components like 'PcComponent', 'LmComponent', 'TapComponent', 'DcComponent', 'RcComponent', 'NcComponent', 'CoComponent', and 'NotificationComponent' also have specific attributes. Associations between these components are shown, such as 'NcAssociatedWithPc', 'DcAssociatedWithNc', 'CoAssociatedWithPc', 'PcAssociatedWithPc', and 'DaAssociatedWithPc'. + +Figure 7-5 – Detail view of control components + +## 7.3 Representation of contexts + +The ClientContext, ServerContext and AdministrativeContext object classes are derived in this Recommendation by pruning and refactoring the ITU-T G.7711 ConstraintDomain object class. Additional classes that contain context-specific attributes are also derived for decorating or augmenting these context object classes. + +The ITU-T G.7711 ExposureContext object class represents that which can be accessed through a ControlPort and the rules regarding who can access the resources exposed by the ExposureContext. The ExposureContext object class exposes the highest-level (outermost) ConstraintDomain object class, which can contain multiple lower level (inner) ConstraintDomains. A new object class ItuExposureContext is derived by pruning and refactoring ExposureContext, extended with additional attributes for management purposes. + +Multiple ExposureContext instances can be created within a ClientContext, ServerContext and AdministrativeContext to represent different exposure policies and scopes. + +The ViewMappingFunction translates the resources, reserved for a specific client, inside the ClientContext instance to a view to be exposed to the upper level controller. Namespace translation may be needed if a different namespace is used by the exposed view from the namespace used in the local resource database. + +The ViewMappingFunction in the server context translates the resources in a view exposed by the lower level controller to the local resource database; a namespace may be translated if different namespaces are used. + +The pruning and refactoring of the ITU-T G.7711 ClientContext, ServerContext, AdministrativeContext and ExposureContext object classes are shown in Figure 7-6. Detailed attributes of these object classes are shown in Figure 7-7. + +![UML Class Diagram showing the hierarchy and associations for Context and Attribute classes.](bd671b21db63e6fdb2196e9b18502aac_img.jpg) + +``` + +classDiagram + class ConstraintDomain { + <> + (CoreModel:ProcessingConstructModel:ObjectClasses) + ConstraintDomain + } + class ExposureContext { + <> + (CoreModel:GeneralControllerModel:ObjectClasses) + ExposureContext + } + class AdministrativeContext { + <> + (itu-mc-mgmt:ObjectClasses) + AdministrativeContext + } + class ClientContext { + <> + (itu-mc-mgmt:ObjectClasses) + ClientContext + } + class ServerContext { + <> + (itu-mc-mgmt:ObjectClasses) + ServerContext + } + class ItuExposureContext { + <> + (itu-mc-mgmt:ObjectClasses) + ItuExposureContext + } + class AcAttribute { + <> + (itu-mc-mgmt:ObjectClasses) + AcAttribute + } + class CcAttribute { + <> + (itu-mc-mgmt:ObjectClasses) + CcAttribute + } + class ScAttribute { + <> + (itu-mc-mgmt:ObjectClasses) + ScAttribute + } + class ItuEcAttribute { + <> + (itu-mc-mgmt:ObjectClasses) + ItuEcAttribute + } + + ConstraintDomain <|-- AdministrativeContext : AdministrativeContextRealizesCd + ConstraintDomain <|-- ClientContext : ClientContextRealizesCd + ConstraintDomain <|-- ServerContext : ServerContextRealizesCd + ExposureContext <|-- ItuExposureContext : ItuExposureContextRealizesEc + + AcAttribute <|-- AdministrativeContext : AcHasAcAttribute + CcAttribute <|-- ClientContext : CcHasCcAttribute + ScAttribute <|-- ServerContext : ScHasScAttribute + ItuEcAttribute <|-- ItuExposureContext : ItuEcHasItuEcAttribute + + ConstraintDomain "1" -- "*" ExposureContext : ExposureContextDefinedByCd + +``` + +The diagram illustrates the object class hierarchy and associations. At the top, **ConstraintDomain** (CoreModel:ProcessingConstructModel:ObjectClasses) is the base class for **AdministrativeContext**, **ClientContext**, and **ServerContext** (allITU-mc-mgmt:ObjectClasses). **ExposureContext** (CoreModel:GeneralControllerModel:ObjectClasses) is the base class for **ItuExposureContext** (itu-mc-mgmt:ObjectClasses). **AcAttribute**, **CcAttribute**, **ScAttribute**, and **ItuEcAttribute** (allITU-mc-mgmt:ObjectClasses) are base classes for **AdministrativeContext**, **ClientContext**, **ServerContext**, and **ItuExposureContext** respectively. A directed association **ExposureContextDefinedByCd** exists from **ConstraintDomain** (multiplicity 1) to **ExposureContext** (multiplicity \*). + +UML Class Diagram showing the hierarchy and associations for Context and Attribute classes. + +Figure 7-6 – Pruning and refactoring for context + +![Figure 7-7 – Detailed view of context. This UML class diagram shows the hierarchy of context object classes. At the top is 'CoreModel:ProcessingConstructModel:ObjectClasses:ConstraintDomain', which contains attributes like 'cdPort', 'ltpDomain: LogicalTerminationPoint', 'cscdDomain: ConfigurationAndSwitchControl', 'equipmentDomain: Equipment', 'rldDomain: ForwardingConstruct', 'ltdDomain: LogicalTerminationPoint', 'controlConstructDomain: ControlConstruct', 'ltpDomain: LogicalTerminationPoint', 'linkDomain: Link', 'runningDomain: RunningOperatingSystem', 'runningSoftwareApplicationDomain: RunningSoftwareApplication', 'runningNativeVmInDomain: RunningNativeVm', 'fileSystemDomain: FileSystem', and 'vmRtdDomain: ViewMappingFunction'. Below it are four specialized context classes: 'AdministrativeContext' (realized by 'AdministrativeContextRealizesCd'), 'ClientContext' (realized by 'ClientContextRealizesCd'), 'ServerContext' (realized by 'ServerContextRealizesCd'), and 'ItuExposureContext' (realized by 'ItuExposureContextRealizesEc'). Each context class has its own set of attributes. 'AdministrativeContext' includes 'vmRtdDomain: ViewMappingFunction', 'controlConstructDomain: ControlConstruct', and 'cdPort'. 'ClientContext' includes 'clientContext: ClientContext', 'serverContext: ServerContext', 'resourceCd: ConstraintDomain', and 'ituExposureContext: ItuExposureContext'. 'ServerContext' includes 'resourceCd: ConstraintDomain', 'ltpDomain: LogicalTerminationPoint', and 'ituExposureContext: ItuExposureContext'. 'ItuExposureContext' includes 'exposurePolicy', 'clientAccessPolicy', 'clientSupportInformation', and 'exposedResourceCd: ConstraintDomain'. Associations show relationships between these classes and other elements like 'Action', 'CcAttribute', 'ScAttribute', and 'ItuCcAttribute'.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +Figure 7-7 – Detailed view of context. This UML class diagram shows the hierarchy of context object classes. At the top is 'CoreModel:ProcessingConstructModel:ObjectClasses:ConstraintDomain', which contains attributes like 'cdPort', 'ltpDomain: LogicalTerminationPoint', 'cscdDomain: ConfigurationAndSwitchControl', 'equipmentDomain: Equipment', 'rldDomain: ForwardingConstruct', 'ltdDomain: LogicalTerminationPoint', 'controlConstructDomain: ControlConstruct', 'ltpDomain: LogicalTerminationPoint', 'linkDomain: Link', 'runningDomain: RunningOperatingSystem', 'runningSoftwareApplicationDomain: RunningSoftwareApplication', 'runningNativeVmInDomain: RunningNativeVm', 'fileSystemDomain: FileSystem', and 'vmRtdDomain: ViewMappingFunction'. Below it are four specialized context classes: 'AdministrativeContext' (realized by 'AdministrativeContextRealizesCd'), 'ClientContext' (realized by 'ClientContextRealizesCd'), 'ServerContext' (realized by 'ServerContextRealizesCd'), and 'ItuExposureContext' (realized by 'ItuExposureContextRealizesEc'). Each context class has its own set of attributes. 'AdministrativeContext' includes 'vmRtdDomain: ViewMappingFunction', 'controlConstructDomain: ControlConstruct', and 'cdPort'. 'ClientContext' includes 'clientContext: ClientContext', 'serverContext: ServerContext', 'resourceCd: ConstraintDomain', and 'ituExposureContext: ItuExposureContext'. 'ServerContext' includes 'resourceCd: ConstraintDomain', 'ltpDomain: LogicalTerminationPoint', and 'ituExposureContext: ItuExposureContext'. 'ItuExposureContext' includes 'exposurePolicy', 'clientAccessPolicy', 'clientSupportInformation', and 'exposedResourceCd: ConstraintDomain'. Associations show relationships between these classes and other elements like 'Action', 'CcAttribute', 'ScAttribute', and 'ItuCcAttribute'. + +Figure 7-7 – Detailed view of context + +### 7.3.1 Client context model + +The ClientContext object class has a subset of the attributes of ConstraintDomain as shown in Figure 7-7. Additional attributes for client context are modelled by a new abstract object class CcAttribute which decorates ClientContext, e.g., pointing to the grouping (via the ConstraintDomain instance) of resources reserved for the client and the ItuParamContext instance(s) within the client context as shown in Figure 7-7. + +### 7.3.2 Server context model + +The ServerContext object class has a subset of attributes of ConstraintDomain as shown in Figure 7-7. Besides these attributes, server context has additional parameters, e.g., pointing to the TAP component, which performs the forwarding point (FP) namespace to SNPP namespace binding when the ServerContext has the visibility of the FP name space. + +The ServerContext object class retains some attributes of ConstraintDomain, including pointing to ControlConstructs that represent the control functions. The control construct in the server context communicates with the corresponding control construct in the client context of the server controller to manage and control the resources. The new attributes for ServerContext are established in a new abstract object class ScAttribute. One new attribute is a pointer to ConstraintDomain and this ConstraintDomain contains the objects representing the set of network resources provided by the lower level controller. + +The attributes for ServerContext and ScAttribute are shown in Figure 7-7. These attributes are determined based on the specification, function and management requirements of server context in clause 6.5.2.3 of [ITU-T G.7718], Figure 7-1 of [ITU-T G.7702] and [ITU-T G.7711]. + +### 7.3.3 Administrative context model + +The administrative context is modelled as AdministrativeContext by pruning and refactoring the ITU-T G.7711 ConstraintDomain object class. It retains some of the attributes of ConstraintDomain + +and is extended with additional attributes established in a new abstract class AcAttribute as shown in Figure 7-6 and Figure 7-7. + +The AdministrativeContext object class represents a set of information used by the administration role, which has unrestricted visibility and authority to perform all necessary operations on the resources within its scope. New ClientContext, ServerContext and ExposureContext instances can be created via the AdministrativeContext. + +The attributes, operations for AdministrativeContext and AcAttribute are shown in Figure 7-7. These attributes are determined based on the definition, function and management requirements of the administrative context in clause 9 of [ITU-T G.7718] and [ITU-T G.7711]. + +## 7.4 Interworking of client, server and administrative contexts + +Figure 7-8 illustrates interworking among the administrative, client and server contexts. It shows, as examples, the interactions among the ConstraintDomain (CD), ControlConstruct (CC), ExposureContext, and ViewMappingFunction (Vmf) object instances. Note that in Figure 7-8, the details of the VN views are intentionally not shown for simplicity. The transport resources and the topology of a VN can be represented by using object classes such as LTP, ForwardingDomain (FD), ForwardingConstruct (FC) and Link. + +![Figure 7-8: Interworking between contexts. The diagram shows two vertical stacks representing SDN controller levels N and N-1. Each stack contains nested boxes for AdministrativeContext CD, ClientContext CD, and ServerContext CD. Inside AdministrativeContext CD are ControlConstruct (CC) instances and a 'CD for CC management'. Inside ClientContext CD are ExposureContext instances (containing 'CD for VN view' and 'VN view'), a ViewMappingFunction (Vmf) instance, and 'Network resource for client'. Inside ServerContext CD are ExposureContext instances (containing 'CD for resource from server' and 'Network resource from server'), a Vmf instance, and 'Network resource from server'. Arrows show interactions: 'Administration role' points to CC; CC points to ExposureContext and ServerContext CD; ExposureContext points to Vmf and Network resource; Vmf points to Network resource. A dashed line with 'Control port' labels connects CC instances between levels N and N-1. A 'CPI' label is near the connection point on level N-1. A label 'To SDN controller level N + 1' is on the far left.](a83ba9e3e2c1e21dd69953a7b09e45b4_img.jpg) + +Figure 7-8: Interworking between contexts. The diagram shows two vertical stacks representing SDN controller levels N and N-1. Each stack contains nested boxes for AdministrativeContext CD, ClientContext CD, and ServerContext CD. Inside AdministrativeContext CD are ControlConstruct (CC) instances and a 'CD for CC management'. Inside ClientContext CD are ExposureContext instances (containing 'CD for VN view' and 'VN view'), a ViewMappingFunction (Vmf) instance, and 'Network resource for client'. Inside ServerContext CD are ExposureContext instances (containing 'CD for resource from server' and 'Network resource from server'), a Vmf instance, and 'Network resource from server'. Arrows show interactions: 'Administration role' points to CC; CC points to ExposureContext and ServerContext CD; ExposureContext points to Vmf and Network resource; Vmf points to Network resource. A dashed line with 'Control port' labels connects CC instances between levels N and N-1. A 'CPI' label is near the connection point on level N-1. A label 'To SDN controller level N + 1' is on the far left. + +Figure 7-8 – Interworking between contexts + +## 7.5 Management-control component attributes + +### 7.5.1 PcComponent attributes + +| Attribute name | Description | Related Recommendations | +|----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------| +| pcIdentifier | PC component supports the configuration of unique identifier (ID) for their points of attachment to the data communication network (DCN), signalling communication network (SCN). | Clause 8.2.1 of [ITU-T G.7718] | +| dcnAddress | The DCN address of the PC component. The DCN address depends on the DCN technology used. | [ITU-T G.7712] | +| managementAndControlProtocolName | The management and control protocol name | | +| protocolConfigurations | Configurations for a specific protocol | | +| _controlPort | Protocol control component communicates with other PC via a list of control port | | +| pcPolicies | Protocol control policies | Clause 8.2.1 of [ITU-T G.7718] | +| _ccComponent | The association with CC | | +| _pcComponent | The association with PC | | +| _daComponent | The association with DA | | +| _rcComponent | The association with RC | | +| _nccComponent | The association with NCC | | + +### 7.5.2 NccComponent attributes + +| Attribute name | Description | Related Recommendations | +|----------------|--------------------------------------------------------------------------|------------------------------| +| callAttributes | The attributes of the calls | Clause 8.2.2 of ITU-T G.7718 | +| _ccComponent | The association with CC | | +| _dsComponent | The association with DS | | +| _controlPort | Protocol control component communicates with other PC via a control port | | +| _viewMapping | The association with view mapping functions | | + +### 7.5.3 DsComponent attributes + +| Attribute name | Description | Related Recommendations | +|-------------------------------|--------------------|--------------------------------| +| nameSpaceBindingConfiguration | Name space binding | Clause 8.2.3 of [ITU-T G.7718] | + +### 7.5.4 TapComponent attributes + +| Attribute name | Description | Related Recommendations | +|-------------------------|--------------------------------------------------------------------------|--------------------------------| +| fpNamespaceToSNPBinding | The binding relationship between FP and SNP | Clause 8.2.4 of [ITU-T G.7718] | +| _controlPort | Protocol control component communicates with other PC via a control port | | +| _lrmComponent | The association with LRM | | + +### 7.5.5 LrmComponent attributes + +| Attribute name | Description | Related Recommendations | +|------------------|--------------------------------------------------------------------------|--------------------------------| +| snpConfiguration | Configuration information for the SNPP | Clause 8.2.5 of [ITU-T G.7718] | +| _controlPort | Protocol control component communicates with other PC via a control port | | +| _rcComponent | The association with RC | | +| _tapComponent | The association with TAP | | + +### 7.5.6 RcComponent attributes + +| Attribute name | Description | Related Recommendations | +|-----------------------------|--------------------------------------------------------------------------|--------------------------------| +| routingInformationBase | The routing information within the RC | Clause 8.2.6 of [ITU-T G.7718] | +| _controlPort | Protocol control component communicates with other PC via a control port | | +| routingAreaConfigurations | Configuration information for routing area | Clause 8.2.6 of [ITU-T G.7718] | +| diverseRoutingConfiguration | Configuration information for diverse routing | Clause 8.2.6 of [ITU-T G.7718] | + +### 7.5.7 CcComponent attributes + +| Attribute name | Description | Related Recommendations | +|--------------------------------|-------------------------------------------------------------|--------------------------------| +| connectionList | List of connections managed by connection control component | Clause 8.2.7 of [ITU-T G.7718] | +| connectionStatusInformation | Status of connections | Clause 8.2.7 of [ITU-T G.7718] | +| connectionProtectionAttributes | Configurations about connection protection | Clause 8.2.7 of [ITU-T G.7718] | +| connectionReroutingAttributes | Configurations about connection re-routing | Clause 8.2.7 of [ITU-T G.7718] | +| _lrmComponent | The association with LRM | | +| _rcComponent | The association with RC | | + +| Attribute name | Description | Related Recommendations | +|-----------------------|--------------------------------------------------------------------------|--------------------------------| +| _controlPort | Protocol control component communicates with other PC via a control port | | + +### 7.5.8 DaComponent attributes + +| Attribute name | Description | Related Recommendations | +|-----------------------------------|--------------------------------------------------------------------------|--------------------------------| +| discoveredResourceInformationBase | Information about the discovered peers | Clause 8.2.8 of [ITU-T G.7718] | +| discoveryDisclosureInformation | Information disclosed to peers | Clause 8.2.8 of [ITU-T G.7718] | +| _pcComponent | The association with PC | | +| _rcComponent | The association with RC | | +| _tapComponent | The association with TAP | | +| _controlPort | Protocol control component communicates with other PC via a control port | | + +### 7.5.9 NotificationComponent attributes + +| Attribute name | Description | Related Recommendations | +|---------------------------|------------------------------------|--------------------------------| +| _controlPort | Notification through a ControlPort | | +| notificationSubscriptions | Notification subscriptions | Clause 8.2.9 of [ITU-T G.7718] | + +## 7.6 Context attributes + +### 7.6.1 AdministrativeContext attributes + +| Attribute name | Description | Related Recommendations | +|---------------------------|----------------------------------------------------|--------------------------------| +| _vmfInDomain | View mapping function in the AdministrativeContext | | +| _controlConstructInDomain | Control constructs in the CD | | +| _pcInDomain | Processing constructs in the CD | | +| _cdPort | Constraint domain port | | + +### 7.6.2 AcAttribute attributes + +| Attribute name | Description | Related Recommendations | +|-----------------------|--------------------------------------------|--------------------------------| +| _resourceCd | The resource constraint domain | | +| _clientContext | The ClientContext in AdministrativeContext | [ITU-T G.7718] | +| _serverContext | The ServerContext in AdministrativeContext | [ITU-T G.7718] | +| _ituExposureContext | The ExposureContext in ServerContext | [ITU-T G.7718] | + +### 7.6.3 AcAction + +| Action name | Description | Related Recommendations | +|---------------------|----------------------------------------|-------------------------| +| createClientContext | The action of creating a ClientContext | [ITU-T G.7718] | +| updateClientContext | The action of updating a ClientContext | [ITU-T G.7718] | +| deleteClientContext | The action of deleting a ClientContext | [ITU-T G.7718] | +| queryClientContext | The action of querying a ClientContext | [ITU-T G.7718] | + +### 7.6.4 ClientContext attributes + +| Attribute name | Description | Related Recommendations | +|---------------------------|--------------------------------------------|-------------------------| +| _vmfInDomain | View mapping function in the ClientContext | | +| _controlConstructInDomain | Control constructs in the CD | | +| _pcInDomain | Processing constructs in the CD | | +| _cdPort | Constraint domain port | | + +### 7.6.5 CcAttribute attributes + +| Attribute name | Description | Related Recommendations | +|---------------------|--------------------------------------|-------------------------| +| _resourceCd | The resource constraint domain | | +| _ituExposureContext | The ExposureContext in ClientContext | | + +### 7.6.6 ServerContext attributes + +| Attribute name | Description | Related Recommendations | +|---------------------------|--------------------------------------------|-------------------------| +| _vmfInDomain | View mapping function in the ServerContext | | +| _controlConstructInDomain | Control constructs in the CD | | +| _pcInDomain | Processing constructs in the CD | | +| _cdPort | Constraint domain port | | + +### 7.6.7 ScAttribute attributes + +| Attribute name | Description | Related Recommendations | +|---------------------|--------------------------------------|-------------------------| +| _resourceCd | The resource constraint domain | | +| _tapInServerContext | The TAP in the ServerContext | | +| _ituExposureContext | The ExposureContext in ServerContext | | + +### 7.6.8 ItuEcAttribute attributes + +| Attribute name | Description | Related Recommendations | +|--------------------------|--------------------------------------|-------------------------| +| exposurePolicy | The policy of exposure | | +| clientAccessPolicy | The TAP in the ServerContext | | +| clientSupportInformation | The ExposureContext in ServerContext | | +| _exposedResourceCd | ConstraintDomain be exposed | | + +# 8 UML model file + +The UML model for this Recommendation developed using the Papyrus open-source modelling tool [b-Eclipse-Papyrus] can be found at [https://www.itu.int/ITU-T/formal-language/itu-t/g/g7719/2021/g7719\\_v1.06\\_uml.zip](https://www.itu.int/ITU-T/formal-language/itu-t/g/g7719/2021/g7719_v1.06_uml.zip). + +This zip file contains the following folders: + +- The G.7719\_v1.06 folder, which contains the following files: + - The Papyrus project file. + - .project. + - The .di, .notation, and .uml files of the itut-mc-mgmt module. + - itut-mc-mgmt.di; + - itut-mc-mgmt.notation; + - itut-mc-mgmt.uml. + - The UmlProfiles sub-folder, which contains the UML Profiles that establish the properties of the UML artefacts. + - The OpenModelProfile folder, which contains the .di, .notation, and uml of the *open model profile*; + - The OpenInterfaceModelProfile folder, which contains the .di, .notation, and uml of the *open model interface profile*; + - The ProfileLifecycleProfile folder, which contains the .di, .notation, and uml of the *profile lifecycle profile*; + - The ClassDiagramStyleSheet.css style sheet. + - The OnfModel sub-folder, which contains the ITU-T G.7711 Core model (identical to the Open Network Foundation (ONF) Core model [b-ONF TR-512]) that is needed (i.e., imported) by the ITU-T G.7719 model. + - The diagrams sub-folder, which contains the portable network graphic (PNG) images of all the class diagrams. + +To load the ITU-T G.7719 UML model into an Eclipse Papyrus workspace, proceed as follows. + +- In the Project Explorer / right click / Import / General / Projects from Folder or Archive / Next / Archive / Select the [ITU-T G.7719] zip file / Open / Select the folders of the models to be loaded (NOTE) / Finish. + +NOTE – If a supporting (i.e., to be imported by [ITU-T G.7719]) model already exists in the workspace, do not select it for loading. + +# Bibliography + +- [b-ITU-T G.7710] Recommendation ITU-T G.7710/Y.1701 (2020), *Common equipment management function requirements*. +- [b-Eclipse-Papyrus] Eclipse Foundation (2020). *Eclipse Papyrus: Modeling environment*, v5.0.0. Available [viewed 2021-08-27] at: +- [b-ONF TR-512] ONF TR-512 (2018), *Core information model (CoreModel)*, v1.4. Available [viewed 2021-08-27] at: [https://www.opennetworking.org/wp-content/uploads/2018/12/TR-512\\_v1.4\\_OnfCoreIm-info.zip](https://www.opennetworking.org/wp-content/uploads/2018/12/TR-512_v1.4_OnfCoreIm-info.zip) + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.772-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.772-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..a38d70f00c5f509f4fac9887015f65f9811cbb22 --- /dev/null +++ b/marked/G/T-REC-G.772-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:757283a7956e0944826355110e7a406113461f1425011d3dc658d00b046aa004 +size 8254 diff --git a/marked/G/T-REC-G.772-199303-I_PDF-E/4d7f667796a8cdcdd745e953ac11e289_img.jpg b/marked/G/T-REC-G.772-199303-I_PDF-E/4d7f667796a8cdcdd745e953ac11e289_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..f883f00cdc6759d4ea51c769b59d35dbabcd05e6 --- /dev/null +++ b/marked/G/T-REC-G.772-199303-I_PDF-E/4d7f667796a8cdcdd745e953ac11e289_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:6bf905ebd17ca1ad877b836882f4cdd219f0326aaa0db3ebe907ea5d27029742 +size 26527 diff --git a/marked/G/T-REC-G.773-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.773-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..856edd620ee4881ec6f1a135962bd51e3761bbfd --- /dev/null +++ b/marked/G/T-REC-G.773-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:ddba2538850c4cfb70d41737d953af441a7329636d9b7d86e177aa20e404d655 +size 8206 diff --git a/marked/G/T-REC-G.773-199303-I_PDF-E/a738993919a50143787084ee7ce6e2f2_img.jpg b/marked/G/T-REC-G.773-199303-I_PDF-E/a738993919a50143787084ee7ce6e2f2_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..ee4149d96059ea3739b9fd76516dd63fe55285ec --- /dev/null +++ b/marked/G/T-REC-G.773-199303-I_PDF-E/a738993919a50143787084ee7ce6e2f2_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:353ca7e0875a1eeba5fd20bbdde16c23efe87f77495cb61b92e5dafb2545fa40 +size 106887 diff --git a/marked/G/T-REC-G.773-199303-I_PDF-E/raw.md b/marked/G/T-REC-G.773-199303-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..acf1bd9164d5cd8a10d7a70043d0d6760b45d626 --- /dev/null +++ b/marked/G/T-REC-G.773-199303-I_PDF-E/raw.md @@ -0,0 +1,824 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.773** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(03/93) + +**GENERAL ASPECTS OF DIGITAL +TRANSMISSION SYSTEMS** + +--- + +**PROTOCOL SUITES FOR Q-INTERFACES +FOR MANAGEMENT OF TRANSMISSION +SYSTEMS** + +**ITU-T Recommendation G.773** + +(Previously "CCITT Recommendation") + +--- + +# FOREWORD + +The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecommunication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +ITU-T Recommendation G.773 was revised by the ITU-T Study Group XV (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). + +# --- NOTES + +1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. + +In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms "CCITT, CCIR or IFRB" or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. + +2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# CONTENTS + +| | | Page | +|-----|----------------------------------------------------------------|-------------| +| 1 | Introduction ..... | 1 | +| 1.1 | Scope ..... | 1 | +| 1.2 | Abbreviations and symbols..... | 1 | +| 2 | Protocol suites overview ..... | 3 | +| 3 | Physical layer ..... | 4 | +| 3.1 | Physical layer for A1 ..... | 4 | +| 3.2 | Physical layer for A2 ..... | 6 | +| 4 | Data link layer ..... | 7 | +| 4.1 | Data link layer for A1 ..... | 7 | +| 4.2 | Data link layer for A2..... | 9 | +| 5 | Network layer for A1 and A2..... | 10 | +| 5.1 | Service ..... | 10 | +| 5.2 | Network protocol ..... | 11 | +| 6 | Mapping functions for A1 and A2 ..... | 12 | +| 6.1 | Introduction ..... | 12 | +| 6.2 | Service ..... | 12 | +| 6.3 | Procedure ..... | 12 | +| 7 | Application layer for A1 and A2..... | 13 | +| 7.1 | Overview ..... | 13 | +| 7.2 | Syntax and encoding..... | 13 | +| 7.3 | Association control ..... | 13 | +| 7.4 | Remote operations ..... | 13 | +| 7.5 | Common management information ..... | 14 | +| 8 | Conformance ..... | 14 | +| | References ..... | 15 | +| | Annex A – Example of extended mode for A1 protocol suite ..... | 16 | +| A.1 | Extended mode ..... | 16 | +| A.2 | Configuration – Full duplex..... | 16 | +| A.3 | Electrical Requirements..... | 16 | +| A.4 | Line code ..... | 16 | +| A.5 | Speed ..... | 16 | + + + +# PROTOCOL SUITES FOR Q-INTERFACES FOR MANAGEMENT OF TRANSMISSION SYSTEMS + +*(Geneva, 1990; revised at Helsinki, 1993)* + +# 1 Introduction + +## 1.1 Scope + +This Recommendation defines the characteristics of protocol suites for Q-interfaces to connect transmission systems/equipments, as defined in Recommendation M.3010 [1]. Protocol suites for Q-interfaces of other systems/equipments will be specified in other Recommendations. The interfaces will support bidirectional data transfer for the management of telecommunications systems. + +This Recommendation defines: + +- the layer services; +- the layer protocols; +- the application service elements and protocols; +- the conformance requirements to be met by an implementation of these interfaces. + +This Recommendation does not define: + +- the structure or meaning of the management information that is transmitted by means of the protocol suites; +- the manner in which management is accomplished as a result of the application protocol exchanges; +- the interactions which result in the use of the application layer protocols. + +## 1.2 Abbreviations and symbols + +### 1.2.1 Abbreviations + +For the purposes of this Recommendation, the following abbreviations apply: + +| | | +|-------|-----------------------------------------------| +| AARE | A-associate response | +| AARQ | A-associate request | +| ACSE | Association control service element | +| AFI | Authority and format identifier | +| ASE | Application service element | +| ASN.1 | Abstract Syntax Notation One | +| CD | Collision detection | +| CLNS | Connectionless-mode network service | +| CMIP | Common management information protocol | +| CMIS | Common management information service | +| CMISE | Common management information service element | +| Conf | Confirm | +| CONS | Connection oriented-mode network service | +| CSMA | Carrier sense multiple access | +| DCE | Data circuit terminating equipment | +| DIS | Draft international standard | + +| | | +|--------|-------------------------------------------------| +| DLC | Data link connection | +| DLS | Data link service | +| DSP | Domain specific part | +| DTE | Data terminal equipment | +| EOC | Embedded operations channel | +| HDLC | High-level data link control | +| Ind | Indication | +| ISO | International Organization for Standardization | +| LLC | Logical link control | +| LME | Layer management entity | +| MAC | Media access control | +| NDM | Normal disconnected mode | +| NE | Network element | +| NRM | Normal response mode | +| NRZ | Non return to zero | +| NRZI | Non return to zero inverted | +| NS | Network service | +| NSAP | Network service access point | +| OSI | Open Systems Interconnection | +| PhC | Physical connection | +| Ph | Physical | +| PhS | Physical service | +| PICS | Protocol implementation conformance statement | +| PLS | Physical layer service | +| QOS | Quality of Service | +| Req | Request | +| Res | Response | +| ROSE | Remote operations service element | +| SDH | Synchronous digital hierarchy | +| SM-ASE | System management-application service element | +| SP | Session protocol | +| TMN | Telecommunications management network | +| UNC | Unbalanced operation normal response mode class | + +### 1.2.2 Symbols and abbreviations used in tables + +- M Mandatory +- The parameter is not present in the interaction described by the service or primitive concerned +- (=) The value of the parameter is equal to the value of the parameter in the column to the left + +# 2 Protocol suites overview + +The structures of the protocol suites with the present layers are shown in Figure 1. The defined communication services and protocols are in accordance with the Open System Interconnection (OSI) reference model [2]. + +![Diagram showing two protocol stacks, A1 and A2, across seven layers. Stack A1 includes SM-ASE, CMISE, ROSE, and ACSE in Layer 7, a Mapping Function in Layer 6, Network layer (ISO 8473, ISO 8473/AD3) in Layer 3, Data link layer (ISO 3309, ISO 7809, ISO 4335) in Layer 2, and Physical layer (ISO 8482, EIA 485) in Layer 1. Stack A2 includes Network layer (ISO 8473) in Layer 3, Data link layer (ISO 8802-2 + DAD2, ISO 8802-3) in Layer 2, and Physical layer (not specified) in Layer 1. Annotations 1 and 2 point to CMISE and ACSE respectively.](a738993919a50143787084ee7ce6e2f2_img.jpg) + +The diagram illustrates two protocol stacks, A1 and A2, mapped against the seven layers of the OSI model. Stack A1 is a more complete suite, including the Application Layer (Layer 7) with SM-ASE, CMISE (ISO 9595, ISO 9596), ROSE (Rec. X.219, X.229), and ACSE (Rec. X.217, X.227). A 'Mapping Function' is shown in Layer 6. Stack A2 is a shorter stack, starting from the Network layer (Layer 3) with ISO 8473. Both stacks share the Data link layer (Layer 2) and Physical layer (Layer 1) protocols. Annotations 1 and 2 point to CMISE and ACSE in Stack A1, indicating their roles in network management transaction-oriented applications. + +| Layer | Stack A1 | Stack A2 | +|---------|----------------------------------------------------------------------------------------|------------------------------------------------| +| Layer 7 | SM-ASE
CMISE ISO 9595, ISO 9596
ROSE Rec. X.219, X.229
ACSE Rec. X.217, X.227 | | +| Layer 6 | Mapping Function | | +| Layer 5 | | | +| Layer 4 | | | +| Layer 3 | Network layer: ISO 8473, ISO 8473/AD3 | Network layer: ISO 8473 | +| Layer 2 | Data link layer: ISO 3309, ISO 7809, ISO 4335 | Data link layer: ISO 8802-2 + DAD2, ISO 8802-3 | +| Layer 1 | Physical layer: ISO 8482, EIA 485 | Physical layer: not specified | + +1 Support ASE for network management transaction-oriented applications + 2 Optionally support ASE + +T1507850-92/d01 + +Diagram showing two protocol stacks, A1 and A2, across seven layers. Stack A1 includes SM-ASE, CMISE, ROSE, and ACSE in Layer 7, a Mapping Function in Layer 6, Network layer (ISO 8473, ISO 8473/AD3) in Layer 3, Data link layer (ISO 3309, ISO 7809, ISO 4335) in Layer 2, and Physical layer (ISO 8482, EIA 485) in Layer 1. Stack A2 includes Network layer (ISO 8473) in Layer 3, Data link layer (ISO 8802-2 + DAD2, ISO 8802-3) in Layer 2, and Physical layer (not specified) in Layer 1. Annotations 1 and 2 point to CMISE and ACSE respectively. + +FIGURE 1/G.773 +**Overview of protocol suites short stacks** + +The protocols for the different layers are based on CCITT Recommendations and/or ISO Standards. + +Two types of protocol suites are recommended to connect transmission systems/equipment to a TMN: + +- The short stack protocol suites (A1 and A2) which will be used mainly as Qx protocol suites as specified in Recommendation M.3010 [1]. +- The full 7 layer stack protocol suites (CONS1, CLNS1 and CLNS2) which can be used as Qx/Q3 protocol suites, as defined by Recommendation M.3010 [1] and are mainly used to satisfy the requirements of complex NEs (e.g. equipment for the synchronous digital hierarchy). + +Protocol profiles for CONS1, CLNS1 and CLNS2 layers 1, 2 and 3 are defined in Recommendation Q.811 [30]. Protocol profiles for CONS1, CLNS1 and CLNS2 layers 4, 5, 6 and 7 are defined in Recommendation Q.812 [31]. + +To support already existing networks and to provide maximum flexibility, several possibilities are defined for layers 1, 2 and 3. Each Administration should select depending on its own specific requirements needed. Layers 5, 6 and 7 are identical for the three protocol suites CONS1, CLNS1 and CLNS2 whilst almost identical requirements apply to layer 4. + +This Recommendation defines the two protocol suites A1 and A2. + +Because of the nulling of the transport layer, session layer and presentation layer for short stack protocol suites, mapping functions have been defined. + +NOTE – The protocol suites CONS1, CLNS1 and CLNS2 replace the B protocol suites from the 1990 issue of this Recommendation. + +In particular: + +CONS1 replaces B1, + +CLNS1 replaces B3, + +CLNS2 replaces B2. + +# **3 Physical layer** + +## **3.1 Physical layer for A1** + +### **3.1.1 Service** + +#### **3.1.1.1 Definition** + +The service definition for the physical layer is in accordance with Recommendation X.211 [3]. + +The following classes of physical services shall be supported: + +- type of transmission is synchronous; +- mode of operation is half-duplex; +- topology is point-to-multipoint by a bus. + +#### **3.1.1.2 Service provided by the physical layer** + +The physical layer provides the physical service primitives and parameters as listed in Table 1. + +The services PhC-Activation and PhC-Deactivation will be provided to the layer management entity (LME) of the physical layer. + +TABLE 1/G.773 + +##### **Provided physical service** + +| Service | Primitive | Parameters | +|------------------|--------------------------|---------------| +| PhC-Activation | Ph-ACTIVATE request | | +| | Ph-ACTIVATE indication | | +| Data Transfer | Ph-DATA request | PhS-User data | +| | Ph-DATA indication | | +| PhC-Deactivation | Ph-DEACTIVATE request | | +| | Ph-DEACTIVATE indication | | + +### **3.1.2 Physical interface** + +#### **3.1.2.1 Physical characteristics** + +##### **3.1.2.1.1 Configuration** + +Serial bus operation in accordance with ISO 84821) [4], in half-duplex mode. + +##### **3.1.2.1.2 Transmission pairs** + +Two screened balanced pairs, one for each direction of transmission. + +##### **3.1.2.1.3 Connector** + +The Administration shall specify the connector type. + +#### **3.1.2.2 Electrical characteristics** + +##### **3.1.2.2.1 Static and dynamic characteristics** + +The static and dynamic characteristics of each bus connection shall be in accordance with ISO 8482 [4]. When all generators connected to the bus are in the high impedance state, the bus shall be set to logical level "1". + +##### **3.1.2.2.2 Bus termination** + +Each bus end shall be terminated in accordance with ISO 8482 [4]. + +##### **3.1.2.2.3 Load connection** + +Each receiver shall present a maximum of one unit load, as defined in ISO 8482 [4], to the bus. The number of load connections is limited to 32. + +##### **3.1.2.2.4 Bit rate** + +The bit rate shall be 19 200 bit/s or 64 000 bit/s. A bit rate of 128 000 bit/s may be necessary in some applications. The bit rate tolerance shall be $\pm 0.05$ %. + +##### **3.1.2.2.5 Turn-off time** + +For bit rates of 19 200 bit/s and 64 000 bit/s a transmitting station shall put its generator in the high impedance state within 0.750 ms from the end of the last bit of the closing flag. For a bit rate of 128 000 bit/s the turn-off time shall be not more than 0.375 ms. This point is not applicable to a primary station (see 4.1.2.1.3). + +1) Compliance assumes that full compatibility with EIA 485 [32] is guaranteed. + +##### 3.1.2.2.6 Switch-on transient + +Following the enabling of the generator an implementation dependent preamble of no more than 4 bit times is allowed. No assumption as to the state of the bus during this preamble is allowed. + +#### 3.1.2.3 Line code + +The line code shall be NRZI. + +##### 3.1.2.3.1 Principle + +Each ISO 8482 [4] transition shall represent a ZERO, and no transition shall represent a ONE bit. + +##### 3.1.2.3.2 Lock-in sequence + +Where required for clock extraction, it shall be possible to send a lock-in sequence containing at least four transitions immediately prior to the beginning of the starting flag of the frame to be transmitted. + +#### 3.1.2.4 Extended mode + +An example of extended mode is given in Annex A. + +## 3.2 Physical layer for A2 + +### 3.2.1 Overview + +Protocol suite A2 employs local area network technology for the physical and data link layers. Administrations will select the appropriate physical medium, e.g. coaxial cable, screened pairs, optical fibre according to technological and operational requirements. + +### 3.2.2 Service + +#### 3.2.2.1 Definition + +The service definition for the physical layer shall comply with that specified in clause 6 of ISO 8802-3 [20]. + +#### 3.2.2.2 Service provided by the physical layer + +All of the primitives defined and listed in Table 2 are mandatory. + +TABLE 2/G.773 + +##### Primitives of the physical layer + +| Primitives | +|------------------------| +| PLS-DATA request | +| PLS-DATA indication | +| PLS-CARRIER indication | +| PLS-SIGNAL indication | + +### 3.2.3 Bit rate + +The bit rate shall be 1 Mbit/s or higher. + +# 4 Data link layer + +## 4.1 Data link layer for A1 + +### 4.1.1 Service + +#### 4.1.1.1 Definition + +The service definition of the data link layer is in accordance with Recommendation X.212 [5]. The class of data link service that shall be provided by the data link layer is + +- connection-mode service. + +#### 4.1.1.2 Service required from the physical layer + +The data link layer requires the Data Transfer service from the physical layer. + +#### 4.1.1.3 Service provided by the data link layer + +The data link layer shall provide the data link service, primitives and parameters as listed in Tables 3 to 5. + +##### 4.1.1.3.1 DLC-Establishment + +See Table 3. + +TABLE 3/G.773 + +###### DLC-Establishment service + +| Parameter name | Request/Indication | Response/Confirmation | +|--------------------|--------------------|-----------------------| +| Called address | M | – | +| Calling address | M | – | +| Responding address | – | M | +| QOS | M | M | + +##### 4.1.1.3.2 DLC-Release + +See Table 4. + +TABLE 4/G.773 + +###### DLC-Release service + +| Parameter name | Request | Indication | +|----------------|---------|------------| +| Originator | – | M | +| Reason | M | M | + +##### 4.1.1.3.3 Normal Data Transfer + +See Table 5. + +TABLE 5/G.773 + +###### Normal Data Transfer service + +| Parameter name | Request | Indication | +|----------------|---------|------------| +| DLS-User data | M | M | + +### 4.1.2 Data link protocol + +The data link protocol is synchronous HDLC type. + +#### 4.1.2.1 HDLC frame structure + +The HDLC frame structure shall conform to ISO 3309 (frame structure) [6]. + +##### 4.1.2.1.1 Addressing field + +The addressing field shall be one octet. + +##### 4.1.2.1.2 Information field + +The information field in any HDLC frame shall be an integral number of octets. + +Information field octets shall be sent least significant bit first. The maximum length of the information field shall be 256 octets. + +##### 4.1.2.1.3 Inter-frame time fill + +A primary station shall transmit contiguous flags as inter-frame time fill. + +#### 4.1.2.2 Addressing + +The secondary station shall be capable of being assigned any address in the range 1 to 254. + +##### 4.1.2.2.1 All-station address + +The address field pattern “11111111” is defined as the all-station address. + +##### 4.1.2.2.2 No-station address + +The address field pattern “00000000” is defined as the no-station address. The no-station address shall never be assigned to a secondary station. + +##### 4.1.2.2.3 Group addresses + +Not used. + +#### 4.1.2.3 HDLC procedure + +The HDLC procedure is defined in ISO 4335 [7]. + +##### 4.1.2.3.1 Commands and response + +The following HDLC commands and responses must be supported: + +- *commands* + - SNRM Set normal response mode + - DISC Disconnect +- *commands or responses* + - I Information + - RR Receive ready + - RNR Receive not ready +- *responses* + - FRMR Frame reject + - UA Unnumbered acknowledgement + - DM Disconnect mode + +##### 4.1.2.3.2 Modes + +Two modes are selected: + +- *one operational mode*: Normal response mode (NRM); +- *one non-operational mode*: Normal disconnected mode (NDM). + +#### 4.1.2.4 Class of procedure + +The unbalanced operation normal response mode class (UNC) as defined in ISO 7809 [8] shall be implemented. + +##### 4.1.2.4.1 HDLC optional functions + +The following HDLC optional functions shall be implemented: + +- unnumbered information (option No. 4); +- data link test (option No. 12). + +#### 4.1.2.5 Other parameters of data link layer + +##### 4.1.2.5.1 Window size + +The window size for unacknowledged frames is to be optional between 1 and 7. The default value is 1. + +##### 4.1.2.5.2 Waiting-time before a repetition + +In the case of no-reply or lost-reply, the primary station shall provide a waiting time function. The waiting-time before a repetition shall be greater than the duration of the longest frame to be sent by the primary station, added to the response-time of the secondary station and the duration of the longest frame to be sent by the secondary station. + +##### 4.1.2.5.3 Number of repetitions + +Under the conditions described in 4.1.2.5.2, the maximum number of repetitions before detecting a no-reply or a lost-reply condition is fixed to 5 (6 requests). + +##### 4.1.2.5.4 Response time + +The secondary station shall commence the opening flag of its response not later than 5 ms after the end of the closing flag of the frame sent from the primary station. + +## 4.2 Data link layer for A2 + +### 4.2.1 Overview + +The data link layer provides the acknowledged connectionless mode service. The access method employed is carrier sense multiple access with collision detection (CSMA/CD). + +### 4.2.2 Media access control (MAC) + +4.2.2.1 The services and protocol of the CSMA/CD access method shall comply with those specified in ISO 8802-3 [20]. + +4.2.2.2 The address length used at the MAC sublayer shall be 48 bits. + +### 4.2.3 Logical link control (LLC) + +4.2.3.1 The definition of the acknowledged connectionless mode LLC service shall comply with that specified in ISO 8802-2/DAD2 [23]. All of the primitives defined for type 3 operation (see Table 6) are mandatory. + +TABLE 6/G.773 + +#### Primitives for type 3 operation + +| | +|-----------------------------------| +| DL-DATA-ACK request/indication | +| DL-DATA-ACK-STATUS indication | +| DL-REPLY request/indication | +| DL-REPLY-STATUS indication | +| DL-REPLY-UPDATE request | +| DL-REPLY-UPDATE-STATUS indication | + +4.2.3.2 The protocol used to provide the acknowledged connectionless mode LLC service shall be as specified in ISO 8802-2 [22] and ISO 8802-2/DAD2 [23]. All of the commands and responses defined for type 3 operation (see Table 7) are mandatory. + +TABLE 7/G.773 + +#### Commands and responses for type 3 operation + +| Commands | Responses | +|----------|-----------| +| AC0 | AC0 | +| AC1 | AC1 | + +# 5 Network layer for A1 and A2 + +## 5.1 Service + +### 5.1.1 Service definition + +The definition of the connectionless mode network service shall comply with that specified in ISO 8348/AD1 [9]. Address formats supported shall conform to ISO 8348/AD2 [10]. + +### 5.1.2 Service required from the data link layer + +The network layer requires the normal Data Transfer service from the data link layer. + +### 5.1.3 Service provided by the network layer + +The network layer shall provide the N-UNITDATA service as listed in Table 8. + +TABLE 8/G.773 + +#### N-UNITDATA service + +| Parameter name | Request | Indication | +|---------------------|---------|------------| +| Source address | M | M(=) | +| Destination address | M | M(=) | +| QOS | M | M | +| NS-User data | M | M(=) | + +## 5.2 Network protocol + +### 5.2.1 General + +The network protocol is as specified in ISO 8473 [11]. The sub-network dependent convergence function required for protocol suite A1 is specified in ISO 8473/AD3 [19]. ISO 8473 [11] defines in addition to the full protocol (see 5.2.4), two subsets namely: + +- inactive network layer protocol (see 5.2.2); +- non-segmenting network layer protocol (see 5.2.3). + +The address part shall have the structure as defined in ISO 8348/AD2 [10]. + +For protocol suite A1 the authority and format identifier (AFI) shall be set to 49, coded by 2 decimal digits as defined in ISO 8348/AD2 [10], which specifies “local” and binary coding of the domain specific part (DSP). + +For protocol suite A2 the authority and format identifier (AFI) shall be set to 38, 39, 48 or 49, coded by two decimal digits as defined in ISO 8348/AD2 [10], which means ISO data country code (ISO DCC) and decimal coding of domain specific part (DSP), ISO DCC and binary coding of DSP, “local” and decimal coding of DSP, or “local” and binary coding of DSP, respectively. + +The full protocol and the two subsets permit the use of known sub-network characteristics and are therefore not sub-network independent. + +Depending on the required usage and the sub-network architecture the full protocol, or one or both subsets, shall be supported by protocol suite A. The selection shall be put in the protocol implementation conformance statement (PICS). + +### 5.2.2 Inactive network layer protocol + +The protocol shall be in accordance with the inactive subset of the protocol as defined in ISO 8473 [11]. + +### 5.2.3 Non-segmenting network layer protocol + +The protocol shall be in accordance with category “type 1” functions of the non-segmenting subset of the protocol as defined in ISO 8473 [11]. + +From the optional functions (type 3) defined in the non-segmenting subset only the “priority function” shall be supported as defined in ISO 8473 [11]. + +### 5.2.4 Full network layer protocol + +The full protocol subset of category "type 1" functions, as specified in ISO 8473 [11], shall be supported. + +An implementation shall not transmit PDUs encoded using the inactive subset. Received PDUs encoded using the inactive subset will be discarded. + +An implementation shall not generate data PDUs without a segmentation part, i.e. the "segmentation permitted flag" shall be set to 1 and the segmentation part shall be included. However, an implementation shall be capable of receiving and correctly processing PDUs which do not contain the segmentation part. + +# 6 Mapping functions for A1 and A2 + +## 6.1 Introduction + +No transport layer, session layer and presentation layer will be specified for protocol suites A1 and A2. + +To provide the required service to the application layer and using the provided service of the network layer a mapping function is defined. + +No protocol for the mapping function is defined. + +## 6.2 Service + +### 6.2.1 Service definition + +The service definition of the mapping function, which provides the required presentation service to the application layer, shall be in accordance with Recommendation X.216 [12]. + +### 6.2.2 Service required from network layer + +The mapping function requires the N-UNITDATA as the connectionless mode network service. + +### 6.2.3 Service provided by the mapping function + +The mapping function shall provide the presentation service as listed in Table 9. + +When ACSE is supported in the application layer the mapping function shall also provide the presentation services P-CONNECT, P-RELEASE, P-U-ABORT and P-P-ABORT. Only the parameters defined as mandatory in Recommendation X.216 [12] shall be supported. The value of the mode parameter of P-CONNECT shall be "normal". + +TABLE 9/G.773 + +#### Service provided by the mapping function + +| Service | Primitive | Parameters | +|---------|-------------------|------------| +| P-DATA | P-DATA request | User data | +| | P-DATA indication | | + +## 6.3 Procedure + +The mapping function will provide the values for the source address, destination address, QOS and NS-User data as required by the network service parameters. The mapping function will translate the presentation addresses to the network service access point (NSAP) addresses and vice versa. It will provide the value of the quality of service parameter of N-UNITDATA request. The NS-user data will be provided by the User data of P-DATA and vice versa. + +NOTE – This is not a mapping protocol. While the service description of this function is standard, the implementation itself needs not to be standardized. + +# 7 Application layer for A1 and A2 + +## 7.1 Overview + +The network management application layer shall provide the CMISE service to the SM-ASE. + +The required application service elements for this service are common management information service element (CMISE) and remote operations service element (ROSE). Some applications may require the addition of the association control service element (ACSE). + +## 7.2 Syntax and encoding + +The application layer protocol data unit presentation is described by using Abstract Syntax Notation One (ASN.1), as defined in Recommendation X.208 [15] and is encoded in accordance with the basic encoding rules for ASN.1, as defined in Recommendation X.209 [16]. + +## 7.3 Association control + +**7.3.1** The ACSE service description is detailed in Recommendation X.217 [25]. When the ACSE is used all of the defined ACSE services (see Table 10) are mandatory. The value of mode parameter of A-ASSOCIATE shall be "normal". + +TABLE 10/G.773 + +**ACSE services and associated APDUs** + +| ACSE service | Associated APDUs | Related P-Service | +|--------------|------------------|-------------------| +| A-ASSOCIATE | AARQ, AARE | P-CONNECT | +| A-RELEASE | RLRQ, RLRE | P-RELEASE | +| A-ABORT | ABRT | P-U-ABORT | +| A-P-ABORT | (None) | P-P-ABORT | + +**7.3.2** The protocol specification for ACSE shall follow Recommendation X.227 [26]. When the ACSE is used all five APDUs (see Table 10) specified in the standard are mandatory. The value of protocol version field of AARQ and AARE shall be "version 1" only. + +## 7.4 Remote operations + +**7.4.1** The remote operations service element (ROSE) shall be a mandatory service element for the protocol suite A1 and A2. The ROSE service description is detailed in Recommendation X.219 [14]. All of the defined ROSE services (see Table 11) are mandatory. + +TABLE 11/G.773 + +### **ROSE services and associated APDUs** + +| ROSE service | Associated APDUs | Related underlying service | +|--------------|------------------|----------------------------| +| RO-INVOK | ROIV | P-DATA | +| RO-RESULT | RORS | P-DATA | +| RO-ERROR | ROER | P-DATA | +| RO-REJECT-U | RORJ | P-DATA | +| RO-REJECT-P | RORJ | P-DATA | + +**7.4.2** The protocol specification for ROSE shall follow Recommendation X.229 [18]. All four APDUs specified in the standard (see Table 11) are mandatory. In addition, the ability to support correct origination and reception of the linked-ID protocol element is required for protocol suite A1 and A2. + +The requirement specified in Table 11 implies association class 3 in ROSE. + +## 7.5 Common management information + +**7.5.1** The common management information service element (CMISE) shall be a mandatory service element for the protocol suite A1 and A2. The CMISE service description is detailed in ISO 9595 [13]. The CMISE services are listed in Table 12. + +TABLE 12/G.773 + +### **CMISE services** + +| Service | Type | +|----------------|-------------------------| +| M-EVENT-REPORT | Confirmed/Non-confirmed | +| M-GET | Confirmed | +| M-SET | Confirmed/Non-confirmed | +| M-ACTION | Confirmed/Non-confirmed | +| M-CREATE | Confirmed | +| M-DELETE | Confirmed | +| M-CANCEL-GET | Confirmed | + +**7.5.2** The protocol specification for CMISE shall follow ISO 9596 [17]. + +# 8 Conformance + +For further study. + +# References + +- [1] CCITT Recommendation M.3010 (1993), *Principles for a telecommunications management network (TMN)*. +- [2] CCITT Recommendation X.200 (1984), *Reference model of open system interconnection for CCITT applications*, (ISO 7498, 1984). +- [3] CCITT Recommendation X.211 (1988), *Physical layer service definition of open system interconnection (OSI) for CCITT applications* (ISO 10022, 1989). +- [4] ISO 8482:1987, *Information processing systems – Data communication – Twisted pair multipoint interconnections*. +- [5] CCITT Recommendation X.212 (1988), *Data link service definition for open system interconnection for CCITT applications* (ISO 8886, 1988). +- [6] ISO 3309:1988, *Information processing systems – Data communication – High-level data link control procedures – Frame structure*. +- [7] ISO 4335:1987, *Information processing systems – Data communication – Consolidation of elements of procedures*. +- [8] ISO 7809:1984, *Information processing systems – Data communication – High-level data link control procedures – Consolidation of classes of procedures*. +- [9] ISO 8348/AD1:1987, *Information processing systems – Data communications – Network service definition; Addendum 1: Connectionless-mode transmission*. +- [10] ISO 8348/AD2:1988, *Information processing systems – Data communications – Network service definition; Addendum 2: Network layer addressing*. +- [11] ISO 8473:1988, *Information processing systems – Data communications – Protocol for providing the connectionless-mode network service*. +- [12] CCITT Recommendation X.216 (1988), *Presentation service definition for open system interconnection for CCITT applications* (ISO 8822, 1987). +- [13] ISO 9595:1992, *Information processing systems – Open systems interconnection – Common management information service definition (CMIS)*. +- [14] CCITT Recommendation X.219 (1988), *Remote operations: Model, notation and service definition* (ISO 9072-1, 1988). +- [15] CCITT Recommendation X.208 (1988), *Specification of Abstract Syntax Notation One (ASN.1)* (ISO 8824, 1987). +- [16] CCITT Recommendation X.209 (1988), *Specification of basic encoding rules for Abstract Syntax Notation One (ASN.1)* (ISO 8825, 1987). +- [17] ISO 9596:1992, *Information processing systems – Open systems interconnection – Common management information protocol specification (CMIP)*. +- [18] CCITT Recommendation X.229 (1988), *Remote operations: Protocols specification*. +- [19] ISO 8473/AD3:1989, *Information processing systems – Data communications – Protocol for providing the connectionless-mode network service; Addendum 3: Provision of the underlying service assumed by ISO 8473 over sub-networks which provide the OSI data link service*. +- [20] ISO 8802-3:1988, *Information processing systems – Local area networks – Part 3 – Carrier sense multiple access with collision detection – Access method and physical layer specifications*. +- [21] CCITT Recommendation E.164 (1988), *Numbering plan for the ISDN era*. +- [22] ISO 8802-2:1988, *Information processing systems – Local area networks – Part 2 – Logical link control*. +- [23] ISO 8802-2/DAD2:1988, *Logical link control; Addendum 2: Acknowledged connectionless-mode service and protocol, type 3 operation*. + +- [24] ISO 4902:1980, *Data communication – 37 pin and 9 pin DTE/DCE interface connectors and pin assignments*. +- [25] CCITT Recommendation X.217 (1988), *Association control service definition for open system interconnections for CCITT applications* (ISO 8649, 1988). +- [26] CCITT Recommendation X.227 (1988), *Association control protocol specification for open system interconnections for CCITT applications* (ISO 8650, 1988). +- [27] IEEE 488 (1978), *Standard digital interface for programmable instrumentation*. +- [28] CCITT Recommendation V.24 (1988), *List of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE)*. +- [29] EIA 449 (1980), *General purpose 37-position and 9-position interface for data terminal equipment and data circuit-terminating equipment employing serial binary data interchange*. +- [30] CCITT Recommendation Q.811 (1993), *Lower layer protocol profiles for the Q3-interface*. +- [31] CCITT Recommendation Q.812 (1993), *Upper layer protocol profiles for the Q3-interface*. +- [32] EIA 485 (1983), *Standard for electrical characteristics of generators and receivers for use in balanced digital multipoint systems*. + +# **Annex A** + +## **Example of extended mode for A1 protocol suite** + +(This annex forms an integral part of this Recommendation) + +## **A.1     Extended mode** + +For those cases where it is required to extend beyond the range of the bus, one of several different capabilities may be used. For the case using modems the requirements of 3.1.2.1 to 3.1.2.3 apply with the following exceptions. + +## **A.2     Configuration – Full duplex** + +The connector shall conform to IEEE 488 [27]. Appropriate signal lines are to be provided for modem control in accordance with Recommendation V.24 [32, 33]. See Table A.1. + +## **A.3     Electrical Requirements** + +Data set control leads shall conform to Recommendation V.24 [28, 29]. + +## **A.4     Line code** + +NRZ line code shall be employed. A separate clock distribution shall be provided. + +## **A.5     Speed** + +The bit rate shall be 9600 bit/s or 64 000 bit/s. Lower speeds, e.g. 1200 bit/s, 2400 bit/s and 4800 bit/s, may be necessary in some applications. + +TABLE A.1/G.773 + +### **Pin description of 24-pin IEEE 488 [27] connector** + +| Pin | Circuit | | | Description | Notes | +|-----|-----------|---------|-----------|------------------------------------|-------| +| | EIA 232-C | EIA 449 | Rec. V.24 | | | +| 1 | AA | Shield | 101 | Protective ground | 1 | +| 13 | AB | SG | 102 | Signal ground | | +| 2 | BA | SD | 103 | Send data A-wire | | +| 14 | | SD | 103 | Send data B-wire | | +| 11 | BB | RD | 104 | Receive data A-wire | | +| 23 | | RD | 104 | Receive data B-wire | | +| 3 | CA | RS | 105 | Request to send A-wire | 2 | +| 15 | | RS | 105 | Request to send B-wire | 2 | +| 7 | CB | CS | 106 | Clear to send A-wire | 2 | +| 19 | | CS | 106 | Clear to send B-wire | 2 | +| 8 | CC | DM | 107 | Data mode A-wire | 2 | +| 20 | | DM | 107 | Data mode B-wire | 2 | +| 9 | CF | RR | 109 | Receiver ready A-wire | 2 | +| 21 | | RR | 109 | Receiver ready B-wire | 2 | +| 6 | DB | ST | 114 | Send timing A-wire (DCE to DTE) | | +| 18 | | ST | 114 | Send timing B-wire (DCE to DTE) | | +| 10 | DD | RT | 115 | Receive timing A-wire (DCE to DTE) | | +| 22 | | RT | 115 | Receive timing B-wire (DCE to DTE) | | + +NOTES + +- 1 Equipment: removable strap to frame ground or other equivalent grounding arrangement. Cable: connected to shield. +- 2 These circuits are optional for connection to an EOC or modem and are not used for connections to a multipoint bus. +- 3 Circuits are grouped by function: ground, data, control, and timing. +- 4 Provision should be made at each interface point on a multipoint bus for the continuation of the interface to the next network element. +- 5 Provision shall be made for the termination of the lines in their characteristic impedance (typically 120 ohms, resistive), should the equipment be at one end of a multipoint bus. +- 6 For further information, see EIA 485 [32] and EIA 449 [29], Recommendation V.24 [28] and IEEE 488 [27]. \ No newline at end of file diff --git a/marked/G/T-REC-G.774.2-200102-I_PDF-E/0a06de972d61ab9bb901bd74dd4ff51f_img.jpg b/marked/G/T-REC-G.774.2-200102-I_PDF-E/0a06de972d61ab9bb901bd74dd4ff51f_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..12c1287dcddba49cd1631ab1fb810d32eba97133 --- /dev/null +++ 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features of transmission equipment + +--- + +**Synchronous digital hierarchy (SDH) – +Management of multiplex-section protection for +the network element view** + +ITU-T Recommendation G.774.3 + +(Formerly CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS + +## TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| General | G.700–G.709 | +| Coding of analogue signals by pulse code modulation | G.710–G.719 | +| Coding of analogue signals by methods other than PCM | G.720–G.729 | +| Principal characteristics of primary multiplex equipment | G.730–G.739 | +| Principal characteristics of second order multiplex equipment | G.740–G.749 | +| Principal characteristics of higher order multiplex equipment | G.750–G.759 | +| Principal characteristics of transcoder and digital multiplication equipment | G.760–G.769 | +| Operations, administration and maintenance features of transmission equipment | G.770–G.779 | +| Principal characteristics of multiplexing equipment for the synchronous digital hierarchy | G.780–G.789 | +| Other terminal equipment | G.790–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +For further details, please refer to the list of ITU-T Recommendations. + +# **Synchronous digital hierarchy (SDH) – Management of multiplex-section protection for the network element view** + +## **Summary** + +This Recommendation provides an information model for the Synchronous Digital Hierarchy (SDH). This model describes the managed object classes and their properties for the protection switching function, as defined in ITU-T G.803 and as related to SDH transmission resources. These objects are useful to describe information exchanged across interfaces defined in ITU-T M.3010 Telecommunications Management Network (TMN) architecture for the management of the protection function. + +| Document History | | +|-------------------------|----------------------------------------------------------------------------------| +| Issue | Notes | +| 2001 | First revision incorporated the changes documented in the G.774.3 Corrigendum 1. | +| 11/1994 | Initial version of the Recommendation. | + +###### **Source** + +ITU-T Recommendation G.774.3 was revised by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 9 February 2001. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2002 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. + +## CONTENTS + +###### Page + +| | | | +|-------|-------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Terms and Definitions ..... | 3 | +| 4 | Abbreviations..... | 3 | +| 5 | Multiplex-section protection management model ..... | 4 | +| 5.1 | Overview..... | 4 | +| 5.2 | SDH multiplex-section protection requirements ..... | 5 | +| 5.2.1 | Generic SDH transmission protection functional requirements ..... | 5 | +| 5.2.2 | SDH multiplex-section specific functional requirements..... | 5 | +| 6 | Managed Object Class Definitions ..... | 6 | +| 6.1 | APS report record ..... | 7 | +| 6.2 | Protected TTP bidirectional ..... | 7 | +| 6.3 | Protected TTP sink..... | 7 | +| 6.4 | Protected TTP source..... | 8 | +| 6.5 | Protection group..... | 8 | +| 6.6 | Protection unit..... | 9 | +| 6.7 | SDH multiplex-section protection group..... | 10 | +| 6.8 | SDH multiplex-section protection unit..... | 10 | +| 6.9 | Unprotected CTP bidirectional ..... | 11 | +| 6.10 | Unprotected CTP sink..... | 11 | +| 6.11 | Unprotected CTP source..... | 11 | +| 7 | Packages..... | 12 | +| 7.1 | Extra traffic control..... | 12 | +| 7.2 | Last attempt result..... | 12 | +| 7.3 | Protection Switch Exercise ..... | 12 | +| 7.4 | Protection Mismatch Status ..... | 12 | +| 7.5 | Priority ..... | 12 | +| 7.6 | SDH Priority ..... | 12 | +| 8 | Attributes ..... | 13 | +| 8.1 | Channel Number ..... | 13 | +| 8.2 | Last attempt result..... | 13 | +| 8.3 | Priority ..... | 13 | +| 8.4 | Protected trail termination point identifier..... | 13 | + +| | | Page | +|------|-----------------------------------------------------|-------------| +| 8.5 | Reported protection unit | 14 | +| 8.6 | Protection group identifier | 14 | +| 8.7 | Protection group type | 14 | +| 8.8 | Protection mismatch status | 14 | +| 8.9 | Protection status | 15 | +| 8.10 | Protection switch mode | 17 | +| 8.11 | Protection unit identifier | 18 | +| 8.12 | Protecting | 18 | +| 8.13 | Reliable resource pointer | 18 | +| 8.14 | Revertive | 18 | +| 8.15 | SDH Priority | 19 | +| 8.16 | Unprotected connection termination point identifier | 19 | +| 8.17 | Unreliable resource pointer | 19 | +| 8.18 | Wait to restore time | 19 | +| 8.19 | Notified protection unit | 20 | +| 9 | Actions | 20 | +| 9.1 | Invoke exercise | 20 | +| 9.2 | Invoke protection | 20 | +| 9.3 | Release protection | 21 | +| 10 | Notifications | 21 | +| 10.1 | Protection Switch Reporting | 22 | +| 11 | Parameters | 22 | +| 11.1 | Invoke Protection Error | 22 | +| 11.2 | Release Protection Error | 22 | +| 11.3 | Protection Status Parameter | 23 | +| 12 | Name Bindings | 23 | +| 12.1 | Protected Trail Termination Point | 24 | +| 12.2 | Protection Group | 25 | +| 12.3 | Aug | 25 | +| 12.4 | Protection unit | 25 | +| 12.5 | Unprotected connection termination point | 25 | +| 13 | Subordination rules | 26 | +| 14 | Pointer constraints | 26 | +| 15 | Supporting ASN.1 productions | 26 | + +| | Page | +|----------------------------------------------------|-------------| +| Appendix I – Naming and Inheritance Diagrams ..... | 30 | +| Appendix II – Examples of MS Protection..... | 32 | + + + +## **Synchronous digital hierarchy (SDH) – Management of multiplex-section protection for the network element view** + +## **1 Scope** + +This Recommendation provides an information model, as related to the protection function for the Synchronous Digital Hierarchy (SDH). It identifies the Telecommunications Management Network (TMN) object classes required for the management of the protection function for SDH network elements. These objects are relevant to information exchanged across standardized interfaces defined in the Recommendation ITU-T M.3010 TMN architecture. + +This Recommendation applies to SDH network elements which perform the Multiplex Section protection function and those systems in the TMN that manage SDH network elements. Functional capabilities of SDH multiplex equipment, particularly the Multiplex Section protection switching function, are given in ITU-T G.783. Performance monitoring requirements for Multiplex Section protection (for the management of SDH equipment with this capability) are provided in ITU-T G.784, however, the information model which supports these can be found in ITU-T G.774.1. + +The new objects defined in this Recommendation supersede those defined in ITU-T G.774.3 (1994). For each object class, attribute, action, notification, parameter defined in this Recommendation it shall be indicated what the impacts upon the existing ITU-T G.774.3 (1994) are. + +## **Structure of this Recommendation** + +Clause 5.1 provides an overview of the SDH protection information model in this Recommendation. Clauses 3 to 15 describe the information model using the notation mechanisms defined in ITU-T X.722 Guidelines for the Definition of Managed Objects. Clause 15 contains the syntax definitions of the information carried in the protocol using Abstract Syntax Notation One (ASN.1) defined in ITU-T X.680-X.683. Naming and Inheritance are diagrammatically shown in informative Appendix I. Diagrams illustrating the application of the SDH protection model are provided in informative Appendix II. + +## **2 References** + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- ITU-T G.707/Y.1322 (2000), *Network node interface for the synchronous digital hierarchy (SDH)*. +- ITU-T G.773 (1993), *Protocol suites for Q-interfaces for management of transmission systems*. +- ITU-T G.774 (2001), *Synchronous digital hierarchy (SDH) – Management information model for the network element view*. +- ITU-T G.783 (2000), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks*. + +- ITU-T G.784 (1999), *Synchronous digital hierarchy (SDH) management.* +- ITU-T G.803 (2000), *Architecture of transport networks based on the synchronous digital hierarchy (SDH).* +- ITU-T G.831 (2000), *Management capabilities of transport networks based on the synchronous digital hierarchy (SDH).* +- ITU-T G.958 (1994), *Digital line systems based on the synchronous digital hierarchy for use on optical fibre cables.* +- ITU-T M.60 (1993), *Maintenance terminology and definitions.* +- ITU-T M.2120 (2000), *PDH path, section and transmission system and SDH path and multiplex section fault detection and localization procedures.* +- ITU-T M.3010 (2000), *Principles for a telecommunications management network.* +- ITU-T M.3013 (2000), *Considerations for a telecommunications management network.* +- ITU-T M.3100 (1995), *Generic network information model.* +- ITU-T Q.811 (1997), *Lower layer protocol profiles for the Q3 and X interfaces.* +- ITU-T Q.812 (1997), *Upper layer protocol profiles for the Q3 and X interfaces.* +- ITU-T Q.822 (1994), *Stage 1, Stage 2 and Stage 3 description for the Q3-interface – Performance management.* +- ITU-T X.680 to X.683 (1997), *Information technology – Abstract Syntax Notation One (ASN.1).* +- ITU-T X.701 (1997), *Information technology – Open Systems Interconnection – Systems management overview.* +- ITU-T X.710 (1997), *Information technology – Open Systems Interconnection – Common management information service.* +- ITU-T X.711 (1997), *Information technology – Open Systems Interconnection – Common management information protocol: Specification.* +- ITU-T X.720 (1992), *Information technology – Open Systems Interconnection – Structure of Management Information: Management information model, plus Amd.1 (1995) and Cor.1 (1994).* +- ITU-T X.721 (1992), *Information technology – Open Systems Interconnection – Structure of management information: Definition of management information, plus Cor.1 (1994), Cor.2 (1996), Cor.3 (1998) and Cor.4 (2000).* +- ITU-T X.722 (1992), *Information technology – Open Systems Interconnection – Structure of management information: Guidelines for the definition of managed objects, plus Amd.1 (1995), Amd.2 (1997) and Cor.1 (1996).* +- ITU-T X.730 (1992), *Information technology – Open Systems Interconnection – Systems management: Object management function, plus Amd.1 (1995) and Amd.1/Cor.1 (1996).* +- ITU-T X.731 (1992), *Information technology – Open Systems Interconnection – Systems management: State management function, plus Amd.1 (1995), Cor.1 (1995) and Amd.1/Cor.1 (1996).* +- ITU-T X.733 (1992), *Information technology – Open Systems Interconnection – Systems management: Alarm reporting function, plus Cor.1 (1994), Amd.1 (1995), Amd.1/Cor.1 (1996) and Cor.2 (1999).* + +- ITU-T X.734 (1992), *Information technology – Open Systems Interconnection – Systems management: Event report management function, plus Cor.1 (1994), Amd.1 (1995), Amd.1/Cor.1 (1996) and Cor.2 (1999)*. +- ITU-T X.735 (1992), *Information technology – Open Systems Interconnection – Systems management: Log control function, plus Amd.1 (1995) and Amd.1/Cor.1 (1996)*. + +## 3 Terms and Definitions + +This Recommendation uses the terms and definitions defined in ITU-T G.774, ITU-T G.784 and ITU-T M.3100. + +## 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|-------|----------------------------------------------------------------------------------| +| APDU | Application Protocol Data Unit | +| APS | Automatic Protection Switching | +| CMIP | Common Management Information Protocol | +| CMIS | Common Management Information Service | +| CTP | Connection Termination Point | +| ISO | International Organization for Standardization | +| ITU | International Telecommunication Union | +| ITU-T | International Telecommunication Union – Telecommunication Standardization Sector | +| LOS | Loss of Signal | +| MS | Multiplex Section | +| MSP | Multiplex Section Protection | +| NE | Network Element | +| OS | Operations System | +| OSI | Open Systems Interconnection | +| Pkg | Package | +| RDN | Relative Distinguished Name | +| SD | Signal Degrade | +| SDH | Synchronous Digital Hierarchy | +| SF | Signal Fail | +| STM-N | Synchronous Transport Module N | +| TMN | Telecommunications Management Network | +| TP | Termination Point | +| TTP | Trail Termination Point | +| WTR | Wait-to-Restore | + +## 5 Multiplex-section protection management model + +### 5.1 Overview + +The SDH information model for the multiplex-section protection switching function is based on the requirements to provide the protection function for transmission in SDH networks. Resources which must be protected have been modelled and are described in ITU-T G.774. They are based on the Generic Network Information Model of ITU-T M.3100. The Generic Network Information Model includes a Termination Point fragment which serves as a structure for specialization for specific technologies such as the SDH. + +The information exchanged at a management interface is modelled using design principles outlined in ITU-T X.720 Management Information Model. Resources are modelled as objects, and the management view of a resource is a managed object. Objects with similar attributes may be grouped into object classes. An object is characterized by its object class and object instance, and may possess multiple attribute types and associated values. The terms managed object class and managed object instance apply specifically to objects that are being managed. This Recommendation specifies the properties of the resource visible for management. + +An object class may be a subclass of another class. A subclass inherits attribute types, packages and behaviours of its super class, in addition to possessing its own specific attributes and properties. The SDH specific object classes are all derived from super classes in the Generic Network Information Model ITU-T M.3100. + +Object classes and attribute types are defined only for the purpose of communicating network management messages between systems, and need not be related to the structure of data within those systems. The object classes defined in this issue of the SDH information model can apply to multiple management functional areas (e.g. fault management and configuration management). + +There are several different viewpoints of management information that may be defined for management purposes. The network element viewpoint is concerned with the information that is required to manage a network element. This refers to information required to manage the protection function and the physical aspects of the network element. This Recommendation addresses only the network element viewpoint. + +#### Revisions that require re-registration + +This clause provides replacement managed object class definitions for the existing ITU-T G.774.3 (1994). Any managed object class replaced by one in this clause is considered to be deprecated. The reasons for the replacement of a managed object class are as follows: + +- 1) The replaced managed object class is faulty and must be fixed. +- 2) The replaced managed object class includes an attribute, package, notification or action which has been re-registered in this or another Recommendation. +- 3) The replaced managed object class inherits from a managed object class which has been re-registered in this or another Recommendation. + +In each case where a class is replaced, the new class will be registered within this Recommendation. The textual label for the class will be revised to include the text "R1". For example, in the managed object class "protectionGroup", the revised label will become "protectionGroupR1". + +Below is a table of classes deprecated from ITU-T G.774.3 (1994) and the G.774.3 classes which replace them: + +#### *Deprecated G.774.3 (1994) Classes* + +protectionGroup +sdhMSPProtectionGroup + +#### *Replacement G.774.3 Classes* + +protectionGroupR1 +sdhMSPProtectionGroupR1 + +### 5.2 SDH multiplex-section protection requirements + +The SDH specific objects specified in this Recommendation shall be used to manage the specific transport resources of SDH network elements, as related to the multiplex-section protection function. Implementations shall conform to both the management information defined in clauses 3 to 15 and the requirements identified in 5.2. + +This Recommendation addresses the management of the automatic protection switching within the network element at the Multiplex Section. The management for multiplex-section protection is based on the protection function described in ITU-T G.803. + +#### 5.2.1 Generic SDH transmission protection functional requirements + +The application specific management models for SDH systems are based on a generic protection model for transmission which satisfies the following common protection requirements: + +- 1) Manage a group of protected resources together with their protecting resources as one protection group, where all members of the protection group in a network element may be configured for: + - a) m:n or 1 + 1 type protection; + - b) revertive or non-revertive type switching; + - c) a specific wait-to-restore time (in the case of revertive systems). +- 2) Indicate the ability of the group of protection units as a whole to provide the protection switching function properly and to send a notification when a change in this operational state occurs. +- 3) Indicate the status of each individual protection unit such as automatic switch completed. +- 4) Send a notification, identifying the protection unit and protection group, when a protection switch event occurs. Specific notification requirements are application specific. +- 5) Send a notification when protection resources are added or removed on the NE. +- 6) For each protected or protecting resource, the ability to perform the following management operations: + - a) invoke a manual protection request; + - b) invoke a forced protection switch; + - c) lockout a protection or working channel; + - d) determine the operational state of the protection group; + - e) indicate a resource as protecting or protected (although most but not all 1 + 1 systems are symmetrical with respect to their protection switching or management functionality). The equipment in the NE determines this operation and provides this indication; + - f) ability to set the switch priority for protected resources in 1:n systems. + +The generic information model for SDH protection management is provided by the **protectionGroup** and **protectionUnit** objects. + +#### 5.2.2 SDH multiplex-section specific functional requirements + +The management information model for linear system multiplex-section protection provided in this Recommendation is based on the generic model and approach to protection, which satisfies the requirements described in 5.2.1. Additionally, the following SDH MS specific requirements exist: + +- 1) Ability to configure the protection switch mode for all protection resources within a protection group as uni- or bidirectional. + +- 2) Ability to send a notification of the protection status of each protected or protecting resource. The protection status value shall indicate the current switch request active or pending (in the case of automatic switch requests only) on any given protection unit (resource). +- 3) Manage extra traffic as follows: + - a) ability to explicitly suspend and resume extra traffic in a protection unit; + - b) prevent extra traffic from being pre-empted by other switch requests; + - c) allow Extra Traffic to be pre-empted by higher priority requests and allow Extra Traffic to be automatically re-established when the higher priority request is removed; + - d) ability to change between modes b) and c). +- 4) Send the following protection switch related notifications: + - a) when a protected resource, having been switched to a protecting resource, is pre-empted by a higher priority request from the same or another protected resource (applicable in 1:n systems); + - b) when a protected resource (unit) is switched onto a protecting resource; + - c) when any switch is released; + - d) when an auto-switch condition exists but cannot be served due to a higher priority request already being served. +- 5) Ability to detect a mismatch between near and far-end protection group type configured values (1 + 1 or 1:n). +- 6) Ability to invoke an exercise on a protected channel. +- 7) Allow only one protecting resource. +- 8) Store the most recent protection switch or exercise result, and provide a notification, against the associated group of protection resources as a whole, when a failure to perform the protection function is detected. + +With respect to ITU-T G.774 termination points which represent the protected (working channels) resources, the following requirements exist: + +- 9) Provide a relationship between the termination points which represent the protected (working channels) and the termination point which represents the protecting (protection channel), and the termination point which reflects the reliable resource. +- 10) In performing a protection switch, update the connectivity pointers of the affected termination points to indicate the new traffic flow. + +The objects relevant to SDH MS Protection Switching are the following sub-classes: + +**sdhMSProtectionGroup** and **sdhMSProtectionUnit**. Additionally, sub-classes of the termination point model are required. These are **protectedTTPSink**, **protectedTTPSource**, **protectedTTPBidirectional**, **unprotectedCTPSink**, **unprotectedCTPSource**, and **unprotectedCTPBidirectional**. + +With respect to the creation/deletion of the protection management objects: + +- 11) It is the responsibility of the NE to create and delete the objects related to protection management according to the make up and mode of the NE. + +## 6 Managed Object Class Definitions + +To allow SDH equipment to be represented in a consistent manner across the interface, the conditional package **crossConnectionObjectPointerPackage** in ITU-T M.3100 is made mandatory in this Recommendation. The following conditional packages inherited from ITU-T M.3100 shall + +not be used when the SDH object classes defined in this Recommendation are instantiated: +**ttpInstancePackage, ctpInstancePackage, networkLevelPackage,** +**characteristicInformationPackage, channelNumberPackage.** + +### 6.1 APS report record + +``` +apsReportRecord MANAGED OBJECT CLASS + DERIVED FROM "Recommendation X.721 | ISO/IEC 10165-2": eventLogRecord; + CHARACTERIZED BY + apsReportRecordPkg PACKAGE + BEHAVIOUR apsReportRecordBeh; + ATTRIBUTES + reportedProtectionUnit GET;;; + REGISTERED AS { g774-03MObjectClass 1 }; + apsReportRecordBeh BEHAVIOUR + DEFINED AS + "An instance of the apsReportRecord object is created when a + protectionSwitchReportingNotification is generated. The protectionStatusParameter + must be included in the management extension. + "; +``` + +### 6.2 Protected TTP bidirectional + +``` +protectedTTPBidirectional MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": trailTerminationPointBidirectional, + protectedTTPSource, + protectedTTPSink; + CHARACTERIZED BY + protectedTTPBidirectionalPkg PACKAGE + BEHAVIOUR protectedTTPBidirectionalBeh;;; + REGISTERED AS { g774-03MObjectClass 2 }; + protectedTTPBidirectionalBeh BEHAVIOUR + DEFINED AS + "The protectedTTPBidirectional object class is a class of objects that represents + the bidirectional protected resources in a protection system. If the SDH + bidirectional multiplex section protection switching function is present, this + object class shall be supported. + "; +``` + +### 6.3 Protected TTP sink + +``` +protectedTTPSink MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": trailTerminationPointSink; + CHARACTERIZED BY + "Recommendation M.3100": crossConnectionPointerPackage, + protectedTTPSinkPkg PACKAGE + BEHAVIOUR protectedTTPSinkBeh; + ATTRIBUTES + protectedTTPId GET;;; + REGISTERED AS { g774-03MObjectClass 3 }; + protectedTTPSinkBeh BEHAVIOUR + DEFINED AS + "The protectedTTPSink object class is a class of objects that represents the + protected resources in a protection system. An instance of this object class is + pointed to by the reliableResourcePointer attribute in an instance of the + protectionUnit object class. The crossConnectionObjectPointer attribute in an + instance of this object class points to its associated protectionUnit instance + which has the reliableResourcePointer attribute pointing back to the instance of + this object class. The upstreamConnectivityPointer in an instance of this object + class points to either null or its associated unprotected CTP object instance; it + indicates the actual signal flow, and when a signal is switched to another unit, + the value of the upstreamConnectivityPointer is updated. If the +``` + +attributeValueChangeNotification package is present, then a change in the value of the supportedByObjectList shall cause an attributeValueChange notification. +"; + +### 6.4 Protected TTP source + +``` +protectedTTPSource MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": trailTerminationPointSource; + CHARACTERIZED BY + "Recommendation M.3100": crossConnectionPointerPackage, + protectedTTPSourcePkg PACKAGE + BEHAVIOUR protectedTTPSourceBeh; + ATTRIBUTES + protectedTTPIdGET;; + REGISTERED AS { g774-03MObjectClass 4 }; +protectedTTPSourceBeh BEHAVIOUR + DEFINED AS + "The protectedTTPSource object class is a class of objects that represents the + protected resources in a protection system. An instance of this object class is + pointed to by the reliableResourcePointer attribute in an instance of the + protectionUnit object class. The crossConnectionObjectPointer attribute in an + instance of this object class points to its associated protectionUnit object + instance which has the reliableResourcePointer attribute pointing back to the + instance of this object class. The downstreamConnectivityPointer in an instance + of this object class points to either null or its associated unprotected CTP + object instance(s); it indicates the actual signal flow, and when a signal is + switched to another unit, the pointer is updated. If the + attributeValueChangeNotification package is present, then a change in the value + of the supportedByObjectList shall cause an attributeValueChange notification. + "; +``` + +### 6.5 Protection group + +``` +protectionGroupR1 MANAGED OBJECT CLASS + DERIVED FROM "Recommendation X.721 | ISO/IEC 10165-2":top; + CHARACTERIZED BY + protectionGroupPkgR1 PACKAGE + BEHAVIOUR protectionGroupR1Beh; + ATTRIBUTES + "Recommendation X.721 | ISO/IEC 10165-2":operationalState GET, + "Recommendation X.721 | ISO/IEC 10165-2":availabilityStatus GET, + protectionGroupId GET, + protectionGroupType GET-REPLACE, + revertive REPLACE-WITH-DEFAULT + DEFAULT VALUE SDHProtASN1.booleanTrueDefault GET-REPLACE, + "Recommendation M.3100":supportedByObjectList GET, + waitToRestoreTime GET-REPLACE; + ACTIONS + invokeProtection, + releaseProtection; + NOTIFICATIONS + protectionSwitchReportingR1, + "Recommendation X.721 | ISO/IEC 10165-2":stateChange;; + CONDITIONAL PACKAGES + "Recommendation M.3100":createDeleteNotificationsPackage + PRESENT IF "an instance supports it", + "Recommendation M.3100":attributeValueChangeNotificationPackage + PRESENT IF "an instance supports it"; + REGISTERED AS { g774-03MObjectClass 12 }; + +protectionGroupR1Beh BEHAVIOUR + DEFINED AS +``` + +"A **protectionGroup** object instance contains zero or more **protectionUnit** objects for defining a protection switching relationship where one or more standby (i.e. backup) entities provide protection for one or more working (i.e. regular or preferred) entities. + +The **invokeProtection** action can be used to request a lockout, a forced switch, or a manual switch (i.e. normal switch) on one or more **protectionUnit** instances contained in the **protectionGroup** object. The **releaseProtection** action can be used to release a lockout, a forced switch, or a manual switch (i.e. normal switch) on one or more **protectionUnit** instances contained in the **protectionGroup** object. + +The **protectionSwitchReporting** notification is emitted from the **protectionGroup** object to report any protection switch events, such as protection switching (forced switch, manual switch, or automatic switch), protection release (release of forced switch, manual switch, or automatic switch), lockout or release of lockout. + +If the **attributeValueChangeNotification** package is present, then changes to the **protectionGroupType** attribute, the **revertive** attribute or the **waitToRestoreTime** attribute shall cause an **attributeValueChange** notification to be emitted. The **protectionGroupType** attribute shall have the value 'colon' when more than one **protectionUnit** is protected. Changing the value of this attribute between 'plus' and 'colon' is allowed when only one protected **protectionUnit** and one protecting **protectionUnit** are contained by the **protectionGroup**. The change from 'plus' to 'colon' is only allowed if the underlying resources support M:N protection."; + +### 6.6 Protection unit + +``` +protectionUnit MANAGED OBJECT CLASS + DERIVED FROM "Recommendation X.721 | ISO/IEC 10165-2": top; + CHARACTERIZED BY + protectionUnitPkg PACKAGE + BEHAVIOUR protectionUnitBeh; + ATTRIBUTES + protectionUnitId GET, + protecting GET, + reliableResourcePointer GET, + unreliableResourcePointer GET;; + CONDITIONAL PACKAGES + priorityPkg PRESENT IF "an instance supports it", + "Recommendation M.3100": attributeValueChangeNotificationPackage + PRESENT IF "an instance supports it"; +REGISTERED AS { g774-03MObjectClass 6 }; +``` + +``` +protectionUnitBeh BEHAVIOUR +``` + +``` +DEFINED AS +``` + +"A **protectionUnit** object represents a protected (i.e. working, regular, or preferred) unit or a protecting (i.e. backup or standby) unit. For a protecting **protectionUnit**, the attribute **protecting** shall have the value TRUE. For a protected **protectionUnit**, the attribute **protecting** shall have the value FALSE. The value of the **unreliableResourcePointer** attribute points to an unreliable resource (e.g. equipment hardware or termination point) that is associated with the **protectionUnit** instance. The value of the **reliableResourcePointer** attribute points to a reliable resource (e.g. termination point) that is associated with the **protectionUnit** instance. + +If the **attributeValueChangeNotificationPackage** is present, then changes to the **unreliableResourcePointer** attribute, the **priority** attribute or the **reliableResourcePointer** attribute shall cause an **attributeValueChange** notification to be emitted. + +``` +"; +``` + +### 6.7 SDH multiplex-section protection group + +``` +sdhMSProtectionGroupR1 MANAGED OBJECT CLASS + DERIVED FROM protectionGroupR1; + CHARACTERIZED BY + sdhMSProtectionGroupR1Pkg PACKAGE + BEHAVIOUR sdhMSProtectionGroupR1Beh; + ATTRIBUTES + protectionSwitchMode GET-REPLACE; + NOTIFICATIONS + protectionSwitchReportingR1 + protectionStatusParameter;; + CONDITIONAL PACKAGES + protectionMismatchStatusPkg + PRESENT IF "the APS protocol is used", + protectionSwitchExercisePkg + PRESENT IF "an instance supports it"; + REGISTERED AS { g774-03MObjectClass 13 }; +``` + +``` +sdhMSProtectionGroupR1Beh BEHAVIOUR + DEFINED AS +``` + +"This object class is used specifically for representing a SDH multiplex-section protection group in a protection system. Only one protecting protection unit is allowed. The **protectionMismatchStatus** indicates a mismatch between the provisioned **protectionGroupType** of this protection group and the provisioned **protectionGroupType** of the far-end. It also indicates mismatch of uni-directional versus bi-directional switch provisioning between the two protection groups."; + +### 6.8 SDH multiplex-section protection unit + +``` +sdhMSProtectionUnit MANAGED OBJECT CLASS + DERIVED FROM protectionUnit; + CHARACTERIZED BY + sdhMSProtectionUnitPkg PACKAGE + BEHAVIOUR sdhMSProtectionUnitBeh; + ATTRIBUTES + channelNumber GET, + protectionStatus GET, + reliableResourcePointer PERMITTED VALUES + SDHProtASN1.SDHMSResourcePointer, + unreliableResourcePointer PERMITTED VALUES + SDHProtASN1.SDHMSResourcePointer;; + CONDITIONAL PACKAGES + sdhPriorityPkg PRESENT IF "this is a 1:n system", + lastAttemptResultPkg PRESENT IF "the APS protocol is used", + extraTrafficControlPkg PRESENT IF "extra traffic may be suspended and + resumed"; + REGISTERED AS { g774-03MObjectClass 8 }; +``` + +``` +sdhMSProtectionUnitBeh BEHAVIOUR + DEFINED AS +``` + +"This object class is specific to SDH multiplex section protection systems. Instances of this object class are used to represent a relationship between a **protectedTTP** and an **unprotectedCTP**. If this is a protecting protection unit, the **reliableResourcePointer** points to the **protectedTTP** for extra traffic or NULL if there is no extra traffic. + +The **channelNumber** attribute value represents the number of the channel used by the SDH MSP protocol, if any. + +If the **sdhMSProtectionUnit** is protecting, then the **channelNumber** attribute shall have the value 0. If the **sdhMSProtectionUnit** is protected, the **channelNumber** attribute shall have a value between 1 and 14. + +For Lockout of protecting unit, protected channels 1 to 14 are incapable of being carried on protection. + +"; + +### 6.9 Unprotected CTP bidirectional + +``` +unprotectedCTPBidirectional MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": +connectionTerminationPointBidirectional, + unprotectedCTPSource, + unprotectedCTPSink; + CHARACTERIZED BY + unprotectedCTPBidirectionalPkg PACKAGE + BEHAVIOUR unprotectedCTPBidirectionalBeh;;; +REGISTERED AS { g774-03MObjectClass 9 }; +unprotectedCTPBidirectionalBeh BEHAVIOUR +DEFINED AS +"The unprotectedCTPBidirectional object class is a class of objects that +represents the unprotected resources in a protection system. +"; +``` + +### 6.10 Unprotected CTP sink + +``` +unprotectedCTPSink MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": connectionTerminationPointSink; + CHARACTERIZED BY + "Recommendation M.3100": crossConnectionPointerPackage, + unprotectedCTPSinkPkg PACKAGE + BEHAVIOUR unprotectedCTPSinkBeh; + ATTRIBUTES + unprotectedCTPID GET;;; +REGISTERED AS { g774-03MObjectClass 10 }; +unprotectedCTPSinkBeh BEHAVIOUR +DEFINED AS +"The unprotectedCTPSink object class is a class of objects that represents the +unprotected resources in a protection system. An instance of this object class is +pointed to by the unreliableResourcePointer attribute in an instance of the +protectionUnit object class (or its subclasses). The crossConnectionObjectPointer +attribute in an instance of this object class points to its associated +protectionUnit object instance which has the unreliableResourcePointer attribute +pointing back to the instance of this object class. +"; +``` + +### 6.11 Unprotected CTP source + +``` +unprotectedCTPSource MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": connectionTerminationPointSource; + CHARACTERIZED BY + "Recommendation M.3100": crossConnectionPointerPackage, + unprotectedCTPSourcePkg PACKAGE + BEHAVIOUR unprotectedCTPSourceBeh; + ATTRIBUTES + unprotectedCTPID GET;;; +REGISTERED AS { g774-03MObjectClass 11 }; +unprotectedCTPSourceBeh BEHAVIOUR +DEFINED AS +"The unprotectedCTPSource object class is a class of objects that represents the +unprotected resources in a protection system. An instance of this object class is +pointed to by the unreliableResourcePointer attribute in an instance of the +protectionUnit object class (or its subclasses). The crossConnectionObjectPointer +attribute in an instance of this object class points to its associated +protectionUnit object instance which has the reliableResourcePointer attribute +pointing back to the instance of this object class. +"; +``` + +## 7 Packages + +### 7.1 Extra traffic control + +``` +extraTrafficControlPkg PACKAGE + BEHAVIOUR extraTrafficControlPkgBeh; + ATTRIBUTES + "Recommendation X.721 | ISO/IEC 10165-2": administrativeState + GET-REPLACE; + REGISTERED AS { g774-03Package 1 }; + extraTrafficControlPkgBeh BEHAVIOUR + DEFINED AS + "Attribute administrativeState is used to suspend or resume extra traffic on the + protecting channel. When in the Locked state, no extra traffic is carried on the + protecting channel, however, this does not prevent protected channel traffic from + being switched to the protecting channel. When unlocked, extra traffic is resumed + on the protecting channel as long as there is no request from a protected channel + of higher priority than on the protecting channel. + "; +``` + +### 7.2 Last attempt result + +``` +lastAttemptResultPkg PACKAGE + ATTRIBUTES + lastAttemptResult GET; + REGISTERED AS { g774-03Package 2 }; +``` + +### 7.3 Protection Switch Exercise + +``` +protectionSwitchExercisePkg PACKAGE + ACTIONS + invokeExercise; + REGISTERED AS { g774-03Package 3 }; +``` + +### 7.4 Protection Mismatch Status + +``` +protectionMismatchStatusPkg PACKAGE + ATTRIBUTES + protectionMismatchStatus GET; + REGISTERED AS { g774-03Package 4 }; +``` + +### 7.5 Priority + +``` +priorityPkg PACKAGE + ATTRIBUTES + priority GET-REPLACE; + REGISTERED AS { g774-03Package 5 }; +``` + +### 7.6 SDH Priority + +``` +sdhPriorityPkg PACKAGE + ATTRIBUTES + sdhPriority PERMITTED VALUES SDHProtASN1.SDHMSPriority GET-REPLACE; + REGISTERED AS { g774-03Package 6 }; +``` + +## 8 Attributes + +### 8.1 Channel Number + +``` +channelNumber ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.Integer; + MATCHES FOR EQUALITY, ORDERING; + BEHAVIOUR channelNumberBeh; +REGISTERED AS { g774-03Attribute 1 }; +channelNumberBeh BEHAVIOUR +DEFINED AS +"This attribute indicates the channel number associated with a protectionUnit. +"; +``` + +### 8.2 Last attempt result + +``` +lastAttemptResult ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.LastAttemptResult; + MATCHES FOR EQUALITY; + BEHAVIOUR lastAttemptResultBeh; +REGISTERED AS { g774-03Attribute 2 }; +lastAttemptResultBeh BEHAVIOUR +DEFINED AS +"The value of the last exercise result or the result of a protection group/unit +diagnostic or switch attempt which performs at least the same functionality as an +exercise, is available from this attribute. If a failure occurs, the +availabilityStatus of the protectionGroup object will be set to degraded. The +successful completion of a protection group/unit diagnostic or switch attempt +which performs at least the same functionality as an exercise causes the +availabilityStatus attribute to be set to NULL (i.e. available), and the +lastAttemptResult value is set to success. +"; +``` + +### 8.3 Priority + +``` +priority ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.Integer; + MATCHES FOR EQUALITY, ORDERING; + BEHAVIOUR priorityBeh; +REGISTERED AS { g774-03Attribute 3 }; +priorityBeh BEHAVIOUR +DEFINED AS +"This attribute specifies the priority of the service (e.g. traffic) carried on +the resource associated with the protected protectionUnit instance. Valid values +for this attribute are integers, where the value 1 indicates the highest +priority, and a larger value indicates a lower priority. +For a protecting protectionUnit, the value of this attribute indicates the +priority of choice of the protecting protectionUnit relative to other available +protecting protectionUnit(s) within the same protectionGroup. The lower the +value, the more preferred the protectionUnit is relative to other +protectionUnits. +"; +``` + +### 8.4 Protected trail termination point identifier + +``` +protectedTTPIId ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.NameType; + MATCHES FOR EQUALITY, ORDERING, SUBSTRINGS; + BEHAVIOUR protectedTTPIIdBeh; +REGISTERED AS { g774-03Attribute 4 }; +protectedTTPIIdBeh BEHAVIOUR +``` + +#### DEFINED AS + +"This attribute is used as an RDN for naming instances of the **protectedTTP** object classes. If the string choice of the syntax is used, then matching on substrings is permitted. If the number choice for the syntax is used, then matching on ordering is permitted. +"; + +### 8.5 Reported protection unit + +reportedProtectionUnit ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.RelativeDistinguishedName; + MATCHES FOR EQUALITY; + REGISTERED AS { g774-03Attribute 5 }; + +### 8.6 Protection group identifier + +protectionGroupId ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.NameType; + MATCHES FOR EQUALITY, ORDERING, SUBSTRINGS; + BEHAVIOUR protectionGroupIdBeh; + REGISTERED AS { g774-03Attribute 6 }; + protectionGroupIdBeh BEHAVIOUR + DEFINED AS + "The **protectionGroupId** attribute is an attribute type whose distinguished value can be used as an RDN when naming an instance of the **protectionGroup** object class. If the string choice of the syntax is used, then matching on substrings is permitted. If the number choice for the syntax is used, then matching on ordering is permitted. +"; + +### 8.7 Protection group type + +protectionGroupType ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.ProtectionGroupType; + MATCHES FOR EQUALITY; + BEHAVIOUR protectionGroupTypeBeh; + REGISTERED AS { g774-03Attribute 7 }; + protectionGroupTypeBeh BEHAVIOUR + DEFINED AS + "This attribute specifies whether the protection scheme used is 1 + 1 (plus) or M:N (colon). M:N includes the cases where M = 1 and/or N = 1. +"; + +### 8.8 Protection mismatch status + +protectionMismatchStatus ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.ProtectionMismatchStatus; + MATCHES FOR EQUALITY; + BEHAVIOUR protectionMismatchStatusBeh; + REGISTERED AS { g774-03Attribute 8 }; + protectionMismatchStatusBeh BEHAVIOUR + DEFINED AS + "This attribute indicates a mismatch between the local and far-end provisioned values for the **protectionGroupType** attribute and has a separate indication for a mismatch between the local and far-end provisioned values for the **protectionSwitchMode** attribute. +"; + +### 8.9 Protection status + +**protectionStatus ATTRIBUTE** + +**WITH ATTRIBUTE SYNTAX SDHProtASN1.ProtectionStatus; +MATCHES FOR EQUALITY, SET-COMPARISON, +SET-INTERSECTION;** + +**BEHAVIOUR protectionStatusBeh;** + +**REGISTERED AS { g774-03Attribute 9 };** + +**protectionStatusBeh BEHAVIOUR** + +**DEFINED AS** + +"This attribute is used to indicate the status of the protection switch in a **protectionUnit** instance. This attribute is set-valued because some requests are allowed to be pending. The following rule shall be followed: Only one of the values **lockout**, **forcedSwitch**, or **manualSwitch** can be present at the same time, either local or remote. It is also possible to have two or more pending automatic switch requests. The **protectionStatus** attribute of a protection Unit which provides protection is used to hold the protection request which is actually performed on that **protectionUnit**. + +Locally invoked management operations (e.g. manual, forced, lockout switch completions) can be overridden at the near end or the far end, but may only be released at the near end. + +Single-ended systems keep the status of local and far-end switch requests as separate entities in the **protectionStatus** attribute. + +The remainder of this behaviour provides the allowable **protectionStatus** attribute values for protected and protecting units for both revertive and non-revertive systems. + +The following allowable **protectionStatus** values are associated with each protected unit: + +- **No Request** – No switch request is present on the unit. +- **Manual Switch to Protecting Complete** – The unit has completed a Manual Switch. +- **Release failed** – A switch has been released or pre-empted and a timeout occurs while waiting for a release of associated bridges, or the near-end switch. +- **Automatic Switch (SF) Pending** – The unit has a Signal Fail condition present and the protecting unit is unavailable. +- **Automatic Switch (SD) Pending** – The unit has a Signal Degrade condition present and the protecting unit is unavailable. +- **Automatic Switch (SF) Complete** – The unit has completed an Automatic Switch to the protecting unit due to a Signal Fail condition. +- **Automatic Switch (SD) Complete** – The unit has completed an Automatic Switch to the protecting unit due to a Signal Degrade condition. +- **Automatic Switch (SF) Present, Operate failed** – An automatic switch (SF) request is in progress and a time-out occurs while waiting for completion. +- **Automatic Switch (SD) Present, Operate failed** – An automatic switch (SD) request is in progress and a time-out occurs while waiting for completion. +- **Force Switch Complete, Automatic Switch (SF) Pending** – The unit has completed a Force Switch. Additionally, the unit has an automatic switch (SF) pending. +- **Force Switch Complete, Automatic Switch (SD) Pending** – The unit has completed a Force Switch. Additionally, the unit has an automatic switch (SD) pending. +- **Automatic Switch Complete, Wait-to-Restore** – The unit has completed an Automatic Switch to the protecting unit. +- **Force Switch Complete** – The unit has completed a Force Switch to the protecting unit. +- **Protected Unit Lockout Completed** – The unit has been locked out from the protecting unit. +- **Protected Unit Lockout complete, Operate Failed** – The unit has been locked out from the protecting unit, and, the previously completed switch could not be released within the expected time-out. When the switch is released, the operate failed status is removed. + +Additionally, the non-revertive protected protection unit has the following status values: + +- **Do Not Revert** – The protected unit has been switched to the protecting unit and the request to do so has been released. The switch to the protecting unit is maintained. +- **Manual Switch to Protected Unit Complete** – The unit has completed a Manual Switch from the protecting unit to the protected unit. +- **Force Switch to Protected Unit Complete** – The unit has completed a Force Switch from the protecting unit to the protected unit. +- **Automatic Switch (SF) to Protected Unit Complete** – The protecting unit has a Signal Fail condition present and traffic is now being carried on the protected unit. +- **Automatic Switch (SD) to Protected Unit Complete** – The protecting unit has a Signal Degrade condition present and traffic is now being carried on the protected unit. +- **Automatic Switch (SD) to Protected Unit Complete, Signal Degrade Present** – The protecting unit has a Signal Degrade condition present and traffic is now being carried on the protected unit. Additionally, the protected unit has a Signal Degrade condition present. +- **Automatic Switch (SF) to Protected Unit Complete, Signal Degrade Present** – The protecting unit has a Signal Fail condition present and traffic is now being carried on the protected unit. Additionally, the protected unit has a Signal Degrade condition present. +- **Force Switch from Protecting Unit Complete, Automatic Switch (SF) Pending** – The unit has completed a Force Switch from the protecting unit to the protected unit. Additionally, the protected unit has an automatic switch (SF) condition present. +- **Force Switch from Protecting Unit Complete, Automatic Switch (SD) Pending** – The unit has completed a Force Switch from the protecting unit to the protected unit. Additionally, the protected unit has an automatic switch (SD) condition present. + +The following allowable **protectionStatus** values are associated with each protecting unit: + +- **No Request** – No request is present on the protecting unit. +- **Manual Switch to Protecting Unit Complete** – The protected unit has completed a Manual Switch. +- **Automatic Switch Complete (SF) to Protecting Unit** – The protected unit has completed an automatic switch (SF) to the protecting unit. +- **Automatic Switch Complete (SD) to Protecting Unit** – The protected unit has completed an automatic switch (SD) to the protecting unit. +- **Automatic Switch Complete (SD) to Protecting Unit, Protecting Unit Signal Degraded** – The protected unit has completed an automatic switch to the protecting unit. Additionally, the protecting unit has a Signal Degrade condition present. This applies to 1:n systems only. +- **Automatic Switch Complete (SF) to Protecting Unit, Protecting Unit Signal Degraded** – The protected unit has completed an automatic switch to the protecting unit. Additionally, the protecting unit has a Signal Degrade condition present. This applies to 1:n systems only. +- **Protecting Unit SD Present** – The protecting unit has a Signal Degrade condition present. This state may also be a result of invalid or toggling APS byte values. This applies to 1:n systems only. +- **Protecting Unit SF Present** – The protecting unit has a Signal Fail condition present. This state may also be a result of invalid or toggling APS byte values. This applies to 1:n systems only. +- **Force Switch Complete to Protecting Unit** – The unit has completed a Force Switch of a protected unit to the protecting unit. +- **Force Switch Complete to Protecting Unit, SD Present on Protecting Unit** – The unit has completed a Force Switch of a protected unit to the protecting unit. Additionally, there is a Signal Degrade present on the protecting unit. + +- **Force Switch Complete to Protecting, SF Present on Protecting Unit** – The unit has completed a Force Switch of a protected unit to the protecting unit. Additionally, there is a Signal Fail (1 + 1 unidirectional systems only) present on the protecting unit. +- **Protecting Unit Locked Out** – The protecting unit has been locked out. +- **Protecting Unit Locked Out, Release Failed** – A release of a lockout is in progress and a timeout occurs waiting for the lockout condition to clear. Additionally, the non-revertive protecting unit has the following values: + - **Do Not Revert** – The protected unit has been switched to the protecting unit and the request to do so has been released. The switch to the protecting unit is maintained. +- **Manual Switch to Protected Unit Complete** – The unit has completed a Manual Switch from the protecting unit to the protected unit. +- **Force Switch to Protected Unit Complete** – The protecting unit has completed a forced switch to the protected unit. +- **Force Switch to Protected Unit Complete, Protecting Unit Signal Degraded** – The protecting unit has completed a forced switch to the protected unit. Additionally, there is a Signal Degrade condition on the protecting unit. +- **Force Switch to Protected Unit Complete, Protecting Unit Signal Failed** – The protecting unit shows a forced switch to the protected unit. Additionally, there is a Signal Fail condition on the protecting unit. +- **Automatic Switch (SF) to Protected Unit Complete** – The protecting unit has a Signal Fail condition present and traffic is now being carried on the protected unit. +- **Automatic Switch (SD) to Protected Unit Complete** – The protecting unit has a Signal Degrade condition present and traffic is now being carried on the protected unit. +- **Automatic Switch Complete (SD) to Protecting, Automatic Switch (SD) to Protected Unit Pending** – The protected unit has completed an automatic switch to the protecting unit. Additionally, the protecting unit has a Signal Degrade condition present. +- **Automatic Switch Complete (SF) to Protecting, Automatic Switch (SD) to Protected Unit Pending** – The protected unit has completed an automatic switch to the protecting unit. Additionally, the protecting unit has a Signal Degrade condition present. + +APS timeout detected by the exerciser, or, during an attempt to invoke a manual or forced switch will not be indicated as APS failure (operate or release fail) in the **protectionStatus** attribute. Instead, the **actionReply** for the invoked action will report this. Additionally, attribute **lastAttemptResult** will provide a record of the failure, until a successful exercise or protection switch causes this attribute to be cleared. + +"; + +### 8.10 Protection switch mode + +``` + +protectionSwitchMode ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.ProtectionSwitchMode; + MATCHES FOR EQUALITY; + BEHAVIOUR protectionSwitchModeBeh; +REGISTERED AS { g774-03Attribute 10 }; +protectionSwitchModeBeh BEHAVIOUR +DEFINED AS +"This attribute specifies whether protection switching is done on a +unidirectional or bidirectional basis. +"; +``` + +### 8.11 Protection unit identifier + +``` +protectionUnitId ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.NameType; + MATCHES FOR EQUALITY, ORDERING, SUBSTRINGS; + BEHAVIOUR protectionUnitIdBeh; +REGISTERED AS { g774-03Attribute 11 }; +protectionUnitIdBeh BEHAVIOUR +DEFINED AS +"The protectionUnitId attribute is an attribute type whose distinguished value +can be used as an RDN when naming an instance of the protectionUnit object class. +If the string choice of the syntax is used, then matching on substrings is +permitted. If the number choice for the syntax is used, then matching on ordering +is permitted. +"; +``` + +### 8.12 Protecting + +``` +protecting ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.Boolean; + MATCHES FOR EQUALITY; + BEHAVIOUR protectingBeh; +REGISTERED AS { g774-03Attribute 12 }; +protectingBeh BEHAVIOUR +DEFINED AS +"This attribute specifies the type of the protectionUnit. A value of TRUE +indicates that the protectionUnit is a protecting (i.e. backup or standby) unit. +A value of FALSE indicates that the protectionUnit is a protected (i.e. a +regular, working, or preferred) unit. +"; +``` + +### 8.13 Reliable resource pointer + +``` +reliableResourcePointer ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.ResourcePointer; + MATCHES FOR EQUALITY; + BEHAVIOUR reliableResourcePointerBeh; +REGISTERED AS { g774-03Attribute 13 }; +reliableResourcePointerBeh BEHAVIOUR +DEFINED AS +"The value of the reliableResourcePointer attribute points to the reliable +resource(s) (e.g. termination point) that is/are associated with the +protectionUnit instance. +"; +``` + +### 8.14 Revertive + +``` +revertive ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.Boolean; + MATCHES FOR EQUALITY; + BEHAVIOUR revertiveBeh; +REGISTERED AS { g774-03Attribute 14 }; +revertiveBeh BEHAVIOUR +DEFINED AS +"This attribute indicates whether the protection scheme is revertive or not. If +the value of this attribute is TRUE, the traffic is returned to the protected +protectionUnit instance that initiated the switch after the fault clears and the +waitToRestoreTime interval (if any) has expired. If the value of this attribute +is FALSE, then after the fault has cleared, traffic does not revert to the +protectionUnit that initiated the switch. +"; +``` + +### 8.15 SDH Priority + +``` +sdhPriority ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.Integer; + MATCHES FOR EQUALITY; + BEHAVIOUR sdhPriorityBeh; +REGISTERED AS { g774-03Attribute 15 }; +sdhPriorityBeh BEHAVIOUR +DEFINED AS +"SDH priority may be High or Low for protected protection units. This is intended +for prioritizing SD and SF conditions on 1:n systems. +"; +``` + +### 8.16 Unprotected connection termination point identifier + +``` +unprotectedCTPID ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.NameType; + MATCHES FOR EQUALITY, ORDERING, SUBSTRINGS; + BEHAVIOUR unprotectedCTPIDBeh; +REGISTERED AS { g774-03Attribute 16 }; +unprotectedCTPIDBeh BEHAVIOUR +DEFINED AS +"This attribute is used as an RDN for naming instances of the unprotectedCTP +object classes. If the string choice of the syntax is used, then matching on +substrings is permitted. If the number choice for the syntax is used, then +matching on ordering is permitted. +"; +``` + +### 8.17 Unreliable resource pointer + +``` +unreliableResourcePointer ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.ResourcePointer; + MATCHES FOR EQUALITY; + BEHAVIOUR unreliableResourcePointerBeh; +REGISTERED AS { g774-03Attribute 17 }; +unreliableResourcePointerBeh BEHAVIOUR +DEFINED AS +"The value of the unreliableResourcePointer attribute points to the unreliable +resource(s) (e.g. equipment hardware or termination point) that is/are associated +with the protectionUnit instance. +"; +``` + +### 8.18 Wait to restore time + +``` +waitToRestoreTime ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.Integer; + MATCHES FOR EQUALITY, ORDERING; + BEHAVIOUR waitToRestoreTimeBeh; +REGISTERED AS { g774-03Attribute 18 }; +waitToRestoreTimeBeh BEHAVIOUR +DEFINED AS +"This attribute specifies the amount of time, in seconds, to wait after a fault +clears before restoring traffic to the protected protectionUnit that initiated +the switching. +"; +``` + +### 8.19 Notified protection unit + +``` +notifiedProtectionUnit ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHProtASN1.ProtectionUnit; + MATCHES FOR EQUALITY; +REGISTERED AS { g774-03Attribute 19 }; +``` + +## 9 Actions + +### 9.1 Invoke exercise + +``` +invokeExercise ACTION + BEHAVIOUR invokeExerciseBeh; + MODE CONFIRMED; + WITH INFORMATION SYNTAX SDHProtASN1.InvokeExerciseArg; + WITH REPLY SYNTAX SDHProtASN1.InvokeExerciseReply; +REGISTERED AS { g774-03Action 1 }; +invokeExerciseBeh BEHAVIOUR +DEFINED AS +"The invokeExercise action can be used to request a protection exercise routine +to be performed on one or more protectionUnit instances contained in the +protectionGroup object. +The action argument contains indications of the protected and protecting units to +which the request applies. If a protecting unit is identified in the +protectedUnits field, or if a protected unit is identified in the protectingUnits +field, the action fails. +The protectionEntity field may be absent, indicating that the request applies to +all contained protection units. +While an exercise is in progress, the value of the protectionStatus attribute +shall continue to indicate No Request. When an exercise routine has completed for +any protectionUnit instances, the lastAttemptResult attribute is updated to +reflect pass or fail for each exercised protection unit. +"; +``` + +### 9.2 Invoke protection + +NOTE – The definition of Lockout, Forced Switch, and Manual Switch is provided in ITU-T G.783. + +``` +invokeProtection ACTION + BEHAVIOUR invokeProtectionBeh; + MODE CONFIRMED; + PARAMETERS invokeProtectionError; + WITH INFORMATION SYNTAX SDHProtASN1.InvokeProtectionArg; +REGISTERED AS { g774-03Action 2 }; +invokeProtectionBeh BEHAVIOUR +DEFINED AS +"The invokeProtection action can be used to request a lockout, a forced switch, +or a manual (i.e. normal switch) on one or more protectionUnit instances +contained in the protectionGroup object. +The action argument contains a request (Forced Switch, Manual Switch, or Lockout) +and indications of the protected and protecting units to which the request +applies. If a protecting unit is identified in the protectedUnits field, or if a +protected unit is identified in the protectingUnits field, the action fails. +If the request is Forced Switch or Manual Switch, the protectedUnits field shall +identify one or more protection units. If only one unit is identified in the +protectedUnits field, and there is only one protecting unit in the protection +group, the protectingUnits field may be omitted. If the protectingUnits field is +present, it shall identify the same number of units as the protectedUnits field. +If the request is Lockout, the protectionEntity field may be absent, indicating +that the request applies to all contained protection units. If the +protectionEntity field is present, any number of protection units may be +``` + +identified in the **protectedUnits** and/or **protectingUnits** field, and either field may be absent. + +For a Lockout request, the specified protected units and/or protecting units are locked out. + +For requests which cannot be completed, either because the request is the protecting unit is serving a request of higher priority (in the error parameter of the CMIP APDU, reason: pre-empted), or failure occurs (failure), or timeout occurs (timeout), the reply shall indicate why the request could not be completed, and the request shall not be made pending. The CMIP error APDU contains the failure reasons. + +"; + +### 9.3 Release protection + +**releaseProtection ACTION** + +**BEHAVIOUR** releaseProtectionBeh; + +**MODE** CONFIRMED; + +**PARAMETERS** releaseProtectionError; + +**WITH INFORMATION SYNTAX** SDHProtASN1.ReleaseProtectionArg; + +**REGISTERED AS** { g774-03Action 3 }; + +releaseProtectionBeh **BEHAVIOUR** + +**DEFINED AS** + +"The **releaseProtection** action can be used to release a lockout, a forced switch, or a manual (i.e. normal switch) on one or more **protectionUnit** instances contained in the **protectionGroup** object. + +The action argument contains a request (Forced Switch, Manual Switch, or Lockout) and indications of the protected and protecting units to which the request applies. If a protecting unit is identified in the **protectedUnits** field, or if a protected unit is identified in the **protectingUnits** field, the action fails. + +If the request is Forced Switch or Manual Switch, the **protectedUnits** field shall identify one or more protection units, and the **protectingUnits** field shall be omitted. For each identified protected unit, if it is not switched to a protecting unit, the action fails. + +If the request is Lockout, the **protectionEntity** field may be absent, indicating that the request applies to all contained protection units. If the **protectionEntity** field is present, any number of protection units may be identified in the **protectedUnits** and/or **protectingUnits** field, and either field may be absent. + +For a Lockout request, the specified protected units and/or protecting units are no longer locked out. That is, the protected units are now under protection and the protecting units are now capable of providing protection. For release requests which cannot be completed, the reply shall indicate why the request could not be completed. + +"; + +## 10 Notifications + +#### Revisions that require re-registration + +This clause provides replacement notification definitions for the existing ITU-T G.774.3 (1994). Any notification replaced by one in this clause is considered to be deprecated. The reason for the replacement of a notification is as follows: + +– The replaced action is faulty and must be fixed. + +In each case where a notification is replaced, the new notification will be registered within this Recommendation. The textual label for the notification will be revised to include the text "R1". For example in "protectionSwitchReporting", the revised label will become "protectionSwitchReportingR1". + +Below is a table of notifications deprecated from ITU-T G.774.3 (1994) and the G.774.3 notifications which replace them: + +`protectionSwitchReporting``protectionSwitchReportingR1` + +### 10.1 Protection Switch Reporting + +``` +protectionSwitchReportingR1 NOTIFICATION + BEHAVIOUR protectionSwitchReportingR1Beh; + WITH INFORMATION SYNTAX SDHProtASN1.ProtectionSwitchReportingInfo + AND ATTRIBUTE IDS + protectingUnitReportedProtectionUnit, + additionalInfo "Recommendation X.721": additionalInformation; +REGISTERED AS { g774-03Notification 2 }; +``` + +``` +protectionSwitchReportingR1Beh BEHAVIOUR +DEFINED AS +"The protectionSwitchReporting notification is emitted from the protectionGroup +object to report any protection switch events."; +``` + +## 11 Parameters + +### 11.1 Invoke Protection Error + +``` +invokeProtectionError PARAMETER + CONTEXT SPECIFIC-ERROR; + WITH SYNTAX SDHProtASN1.InvokeProtectionError; + BEHAVIOUR invokeProtectionErrorBeh; +REGISTERED AS { g774-03Parameter 1 }; +invokeProtectionErrorBeh BEHAVIOUR +DEFINED AS +"This parameter is included in the error parameter of the CMIP APDU when the +invoke protection action fails. The pre-empted choice means that a higher +priority switch request exists on the protecting protection unit. The failure +choice indicates that the request has not been performed due to an abnormal +condition on the protection system. The timeout choice indicates that the +protection switch has not been performed in the required time frame. +"; +``` + +### 11.2 Release Protection Error + +``` +releaseProtectionError PARAMETER + CONTEXT SPECIFIC-ERROR; + WITH SYNTAX SDHProtASN1.ReleaseProtectionError; + BEHAVIOUR releaseProtectionErrorBeh; +REGISTERED AS { g774-03Parameter 2 }; +releaseProtectionErrorBeh BEHAVIOUR +DEFINED AS +"This parameter is included in the error parameter of the CMIP APDU when the +release protection action fails. The failure choice indicates that the request +has not been performed due to an abnormal condition on the protection system. The +timeout choice indicates that the protection switch has not been performed in the +required time frame. +"; +``` + +### 11.3 Protection Status Parameter + +``` +protectionStatusParameter PARAMETER + CONTEXT EVENT-INFO; + WITH SYNTAX SDHProtASN1.ProtectionStatusParameter; + BEHAVIOUR protectionStatusParameterBeh; +REGISTERED AS { g774-03Parameter 3 }; +protectionStatusParameterBeh BEHAVIOUR +DEFINED AS +"This parameter is included in the additional info parameters of the protection +switching reporting notification. +This notification is sent by the protection group according to the following +rules. There are several cases: +- The switch from protected to protecting or protecting to protected has been +done without pre-empting an existing switch. In this case the old and new +values of the Protection Status attribute of the protecting channel shall be +reported in the notification by means of the oldProtectionStatus and +newProtectionStatus parameters respectively. +- A switch is preformed by pre-empting an existing one. In this case the old +and new values of the Protection Status attribute of the protecting channel +shall be reported in the notification by means of the oldProtectionStatus +and newProtectionStatus parameters respectively. +- An auto-switch condition exists on a channel but the auto-switch cannot be +served due to the unavailability of the channel that otherwise protects it. +In this case the oldProtectionStatus and newProtectionStatus parameters +refer to the protection status attribute value of the channel on which the +autoswitch condition arises. The exception is when the channel is already +forced or locked out, in which case no notification is sent. +- A working channel (protected unit) has been locked out or released from +lockout without modifying any existing switch. In this case the +oldProtectionStatus and newProtectionStatus parameters refer to the +protection status attribute value of the working channel which has been +locked out. +- A protection channel (protecting unit) has been locked out or release from +lockout without modifying the existing switch. In this case the +oldProtectionStatus and newProtectionStatus parameters refer to the +protection status attribute value of the protection channel which has been +locked out. +- The protectionSwitchReporting is not sent when the automatic switch +condition is toggling between SD, SF and WTR condition. While in the lockout +of forced switch state no notification is sent except for ending of release +failure. +"; +``` + +## 12 Name Bindings + +#### Revisions that require re-registration + +This clause provides replacement namebinding definitions for the existing ITU-T G.774.3 (1994). Any namebinding replaced by one in this clause is considered to be deprecated. The reasons for the replacement of a namebinding are as follows: + +- 1) The replaced namebinding is faulty and must be fixed. +- 2) The replaced namebinding refers to a superior managed object class which has been re-registered in this or another Recommendation. +- 3) The replaced namebinding refers to a subordinate managed object class which has been re-registered in this or another Recommendation. +- 4) The replaced namebinding refers to a naming attribute which has been re-registered in this or another Recommendation. + +In each case where a namebinding is replaced, the new namebinding will be registered within this Recommendation. The textual label for the namebinding will be revised to include the text "R1". For example, in the namebinding "protectionGroup-managedElement", the revised label will become namebinding "protectionGroupR1-managedElement". Note the "R1" is placed immediately following the revised class which impacts the namebinding. + +Below is a table of namebindings deprecated from Recommendation G.774.3 (1994) and the G.774.3 namebindings which replace them: + +#### *Deprecated G.774.3 (1994) Namebindings* + +#### *Replacement G.774.3 Namebindings* + +protectionGroup-managedElement +protectionUnit-protectionGroup + +protectionGroupR1-managedElement +protectionUnit-protectionGroupR1 + +### 12.1 Protected Trail Termination Point + +``` +protectedTTPBidirectional-sdhNE NAME BINDING + SUBORDINATE OBJECT CLASS protectedTTPBidirectional; + NAMED BY SUPERIOR OBJECT CLASS "Recommendation G.774": sdhNE; + WITH ATTRIBUTE protectedTTPId; + BEHAVIOUR protectedTTPBidirectional-sdhNEBeh; +REGISTERED AS { g774-03NameBinding 1 }; +protectedTTPBidirectional-sdhNEBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex section +protection switching function is present. Instances of this object class may also +be instantiated when other types of protection switching functions, such as path +protection, are present. +"; +protectedTTPSink-sdhNE NAME BINDING + SUBORDINATE OBJECT CLASS protectedTTPSink; + NAMED BY SUPERIOR OBJECT CLASS "Recommendation G.774": sdhNE; + WITH ATTRIBUTE protectedTTPId; + BEHAVIOUR protectedTTPSink-sdhNEBeh; +REGISTERED AS { g774-03NameBinding 2 }; +protectedTTPSink-sdhNEBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex section +protection switching function is present. Instances of this object may also be +instantiated when other types of protection switching functions, such as path +protection, are present. +"; +protectedTTPSource-sdhNE NAME BINDING + SUBORDINATE OBJECT CLASS protectedTTPSource; + NAMED BY SUPERIOR OBJECT CLASS "Recommendation G.774": sdhNE; + WITH ATTRIBUTE protectedTTPId; + BEHAVIOUR protectedTTPSource-sdhNEBeh; +REGISTERED AS { g774-03NameBinding 3 }; +protectedTTPSource-sdhNEBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex section +protection switching function is present. Instances of this object class may also +be instantiated when other types of protection switching functions, such as path +protection, are present. +"; +``` + +### 12.2 Protection Group + +``` +protectionGroupR1-managedElement NAME BINDING + SUBORDINATE OBJECT CLASS protectionGroupR1 AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS + "Recommendation M.3100":managedElement AND SUBCLASSES; + WITH ATTRIBUTE protectionGroupId; +REGISTERED AS { g774-03NameBinding 12 }; +``` + +### 12.3 Aug + +``` +augBidirectional-protectedTTPBidirectional NAME BINDING + SUBORDINATE OBJECT CLASS "Recommendation G.774": augBidirectional; + NAMED BY SUPERIOR OBJECT CLASS protectedTTPBidirectional; + WITH ATTRIBUTE "Recommendation G.774": augId; + BEHAVIOUR augBidirectional-protectedTTPBidirectionalBeh; +REGISTERED AS { g774-03NameBinding 5 }; +augBidirectional-protectedTTPBidirectionalBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex-section +protection switching function is present. +"; +augSink-protectedTTPSink NAME BINDING + SUBORDINATE OBJECT CLASS "Recommendation G.774": augSink; + NAMED BY SUPERIOR OBJECT CLASS protectedTTPSink; + WITH ATTRIBUTE "Recommendation G.774": augId; + BEHAVIOUR augSink-protectedTTPSinkBeh; +REGISTERED AS { g774-03NameBinding 6 }; +augSink-protectedTTPSinkBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex-section +protection switching function is present. +"; +augSource-protectedTTPSource NAME BINDING + SUBORDINATE OBJECT CLASS "Recommendation G.774": augSource; + NAMED BY SUPERIOR OBJECT CLASS protectedTTPSource; + WITH ATTRIBUTE "Recommendation G.774": augId; + BEHAVIOUR augSource-protectedTTPSourceBeh; +REGISTERED AS { g774-03NameBinding 7 }; +augSource-protectedTTPSourceBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex-section +protection switching function is present. +"; +``` + +### 12.4 Protection unit + +``` +protectionUnit-protectionGroupR1 NAME BINDING + SUBORDINATE OBJECT CLASS + protectionUnit AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS protectionGroupR1 AND SUBCLASSES; + WITH ATTRIBUTE protectionUnitId; +REGISTERED AS { g774-03NameBinding 13 }; +``` + +### 12.5 Unprotected connection termination point + +``` +unprotectedCTPBidirectional-msTTPBidirectional NAME BINDING + SUBORDINATE OBJECT CLASS unprotectedCTPBidirectional; + NAMED BY SUPERIOR OBJECT CLASS "Recommendation G.774": msTTPBidirectional; + WITH ATTRIBUTE unprotectedCTPID; + BEHAVIOUR unprotectedCTPBidirectional-msTTPBidirectionalBeh; +REGISTERED AS { g774-03NameBinding 9 }; +``` + +``` + +unprotectedCTPBidirectional-msTTPBidirectionalBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex section +protection switching function is present. +"; +unprotectedCTPSink-msTTPSink NAME BINDING + SUBORDINATE OBJECT CLASS unprotectedCTPSink; + NAMED BY SUPERIOR OBJECT CLASS "Recommendation G.774": msTTPSink; + WITH ATTRIBUTE unprotectedCTPID; + BEHAVIOUR unprotectedCTPSink-msTTPSinkBeh; +REGISTERED AS { g774-03NameBinding 10 }; + +unprotectedCTPSink-msTTPSinkBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex section +protection switching function is present. +"; + +unprotectedCTPSource-msTTPSource NAME BINDING + SUBORDINATE OBJECT CLASS unprotectedCTPSource; + NAMED BY SUPERIOR OBJECT CLASS "Recommendation G.774": msTTPSource; + WITH ATTRIBUTE unprotectedCTPID; + BEHAVIOUR unprotectedCTPSource-msTTPSourceBeh; +REGISTERED AS { g774-03NameBinding 11 }; + +unprotectedCTPSource-msTTPSourceBeh BEHAVIOUR +DEFINED AS +"The subordinate managed objects are instantiated when the multiplex section +protection switching function is present. +"; + +``` + +## 13 Subordination rules + +None. + +## 14 Pointer constraints + +None. + +## 15 Supporting ASN.1 productions + +The following text replaces the entire text within clause 15/G.774.3 (1994). No textual changes (except adding of protectionUnit, which was missing) have been made; the ASN.1 definitions have simply been alphabetically ordered for convenience. + +``` + +SDHProtASN1 {itu-t(0) recommendation(0) g(7) g774(774) hyphen(127) prot(03) +informationModel(0) asn1Module(2) sdhmsp(0)} + +``` + +``` + +DEFINITIONS IMPLICIT TAGS ::= +BEGIN + +``` + +``` + +-- EXPORTS everything + +``` + +``` + +IMPORTS + +``` + +``` + +NameType + +``` + +``` + + FROM + +``` + +``` + + ASN1DefinedTypesModule {itu-t(0) recommendation m gnm(3100) + +``` + +``` + + informationModel(0) asn1Modules(2) asn1DefinedTypesModule(0)} + +``` + +``` + +RelativeDistinguishedName + +``` + +``` + + FROM + +``` + +``` + + InformationFramework {joint-iso-itu-t ds(5) modules(1) + +``` + +``` + + informationFramework(1)} + +``` + +``` + +ObjectInstance + FROM + CMIP-1 {joint-iso-ccitt ms(9) cmip(1) modules(0) protocol(3)} + AdditionalInformation, ManagementExtension + FROM + Attribute-ASN1Module {joint-iso-itu-t ms(9) smi(3) part2(2) + asn1Module(2) 1}; + +sdhProt OBJECT IDENTIFIER ::= {itu-t(0) recommendation(0) g(7) g774(774) + hyphen(127) + prot(03) informationModel(0)} + +g774-03MObjectClass OBJECT IDENTIFIER ::= {sdhProt managedObjectClass(3)} + +g774-03Attribute OBJECT IDENTIFIER ::= {sdhProt attribute(7)} + +g774-03NameBinding OBJECT IDENTIFIER ::= {sdhProt nameBinding(6)} + +g774-03Action OBJECT IDENTIFIER ::= {sdhProt action(9)} + +g774-03Notification OBJECT IDENTIFIER ::= {sdhProt notification(10)} + +g774-03Parameter OBJECT IDENTIFIER ::= {sdhProt parameter(5)} + +g774-03Package OBJECT IDENTIFIER ::= {sdhProt package(4)} + +-- default value definitions +booleanTrueDefault Boolean ::= TRUE + +-- supporting productions +AutoSwitchReason ::= CHOICE { + waitToRestore [0] NULL, + signalDegrade [1] NULL, + signalFail [2] NULL} + +Boolean ::= BOOLEAN + +FromAndToProtectionUnit ::= CHOICE { + fromProtectionUnitNumber [0] RelativeDistinguishedName , + toProtectionUnitNumber [1] RelativeDistinguishedName } + +--The fromProtectionUnitNumber is used for protecting protection unit in order to +--hold the name of the protected protection unit which has been protected by that +--protecting protection unit. The toProtectionUnitNumber is used for protected +--protection unit in order to hold the number of the protecting protection unit +--to which it has been switched to. In case of a MSP 1+1 system these parameters +--are not mandatory.-- + +Integer ::= INTEGER + +InvokeExerciseArg ::= SEQUENCE { + protectionEntity ProtectionEntity OPTIONAL, -- if absent, all PUs + otherInfo SET OF ManagementExtension OPTIONAL} + +InvokeExerciseReply ::= SET OF SEQUENCE { + protectionUnit RelativeDistinguishedName, + result LastAttemptResult} + +InvokeProtectionArg ::= SEQUENCE { + switchType SwitchType, + protectionEntity ProtectionEntity OPTIONAL, -- if absent, all PUs + otherInfo SET OF ManagementExtension OPTIONAL} + +``` + +``` + +InvokeProtectionError ::= ENUMERATED { + preempted (0), + failure (1), + timeout (2)} + +LastAttemptResult ::= CHOICE { + success [0] NULL, -- default value + denied [1] NULL, + fail [2] RxBTxAPS} + +ProtectionDirection ::= ENUMERATED { + transmit (0), + receive (1), + bidirectional (2) } + +ProtectionEntity ::= SEQUENCE { + protectedUnits [0] SEQUENCE OF RelativeDistinguishedName OPTIONAL, + protectingUnits [1] SEQUENCE OF RelativeDistinguishedName OPTIONAL +} + +--In case of a 1+1 non-revertive MSP system for a manual switch from the +--protecting protection unit to the protected one, the protectingUnits field +--shall be used and shall indicate the protection unit which has the channel +--number 0. If both fields are present they should be compatible sequences-- + +ProtectionGroupType ::= ENUMERATED { + plus (0), -- 1+1 (1 plus 1) or hot-standby + colon (1) -- M:N (M for N) +} + +ProtectionMismatchStatus ::= SEQUENCE { + uniBi [0] BOOLEAN, + plusColon [1] BOOLEAN} + +ProtectionStatus ::= SET OF CHOICE { + noRequest [0] NULL, + doNotRevert [1] NULL, + manualSwitch [2] SEQUENCE { + requestSource [0] RequestSource OPTIONAL, + switchStatus [1] SwitchStatus, + relatedChannel [2] FromAndToProtectionUnit}, + autoSwitch [3] SEQUENCE { + requestSource [0] RequestSource OPTIONAL, + switchStatus [1] SwitchStatus, + relatedChannel [2] FromAndToProtectionUnit, + autoSwitchReason [3] AutoSwitchReason}, + forcedSwitch [4] SEQUENCE { + requestSource [0] RequestSource OPTIONAL, + switchStatus [1] SwitchStatus , + relatedChannel [2] FromAndToProtectionUnit}, + lockout [5] SEQUENCE { + requestSource [0] RequestSource OPTIONAL, + switchStatus [1] SwitchStatus}, + releaseFailed [6] NULL, + protectionFailCondApsInvalid [7] BOOLEAN, + protectionFailCondChannelMismatch [8] BOOLEAN } + +ProtectionStatusParameter ::= SEQUENCE { + oldProtectionStatus ProtectionStatus, + newProtectionStatus ProtectionStatus, + psDirection ProtectionDirection DEFAULT bidirectional} + +``` + +``` + +ProtectionSwitchMode ::= ENUMERATED { + bidirectional (0), + unidirectional (1)} + +ProtectionSwitchReportingInfo ::= SEQUENCE { + protectingUnit RelativeDistinguishedName, + additionalInfo AdditionalInformation} + +ProtectionUnit ::= CHOICE { + protectingUnit [0] RelativeDistinguishedName, + protectedUnit [1] RelativeDistinguishedName } + +ReleaseProtectionArg ::= SEQUENCE { + switchType SwitchType, + protectionEntity ProtectionEntity, + otherInfo SET OF ManagementExtension OPTIONAL} + +ReleaseProtectionError ::= ENUMERATED { + failure (0), + timeout (1)} + +RequestSource ::= ENUMERATED { + local (0), + remote (1) } + +ResourcePointer ::= CHOICE { + null NULL, + objectInstances SEQUENCE OF ObjectInstance } + +RxTxAPS ::= SEQUENCE { + rxAPSvalue [0] INTEGER, + txAPSvalue [1] INTEGER} -- APS byte 1 in low order byte , byte 2 + -- in high order byte + +SDHMSPriority ::= Integer(1 .. 2) +-- 1 = high priority, 2 = low priority + +SDHMSResourcePointer ::= ResourcePointer(WITH COMPONENTS { + ..., + objectInstances(SIZE(1)) +} ) + +SwitchStatus ::= ENUMERATED { + pending (0), + completed (1), + operateFailed (2)} + +SwitchType ::= ENUMERATED { + manual (0), + forced (1), + lockout (2)} + +END + +``` + +## APPENDIX I + +### **Naming and Inheritance Diagrams** + +See Figures I.1 and I.2. + +![Inheritance diagrams for SDH MS Protection. The first diagram shows the hierarchy for connection termination points (Sink, Source, Bidirectional) and unprotected CTPs. The second diagram shows the hierarchy for trail termination points (Sink, Source, Bidirectional) and protected TTPs. The third diagram shows the hierarchy for top (X.721) objects like protection unit, protection group, and event log record, leading to sdhMsProtectionUnit, sdhMsProtectionGroup, and apsReportRecord. A legend at the bottom left indicates that shaded boxes are 'Not defined in this Recommendation.'](6629e8a87e7552e2454b7c3e9f6d73a0_img.jpg) + +``` +graph TD; subgraph CTP_Hierarchy; CTPS[connectionTerminationPointSink (M.3100)]; CTPSO[connectionTerminationPointSource (M.3100)]; CTPB[connectionTerminationPointBidirectional (M.3100)]; UCTPS[unprotectedCTPSink]; UCTPSO[unprotectedCTPSource]; UCTPB[unprotectedCTPBidirectional]; CTPS --- CTPB; CTPSO --- CTPB; CTPB --- UCTPS; CTPB --- UCTPSO; UCTPS --- UCTPB; UCTPSO --- UCTPB; end; subgraph TTP_Hierarchy; TTPTS[trailTerminationPointSink (M.3100)]; TTPTSO[trailTerminationPointSource (M.3100)]; TTPTB[trailTerminationPointBidirectional (M.3100)]; PTTPS[protectedTTPSink]; PTTPSO[protectedTTPSource]; PTTPB[protectedTTPBidirectional]; TTPTS --- TTPTB; TTPTSO --- TTPTB; TTPTB --- PTTPS; TTPTB --- PTTPSO; PTTPS --- PTTPB; PTTPSO --- PTTPB; end; subgraph Top_Hierarchy; TOP[top (X.721)]; ELR[eventLogRecord (X.721)]; PU[protectionUnit]; PG[protectionGroup]; ARR[apsReportRecord]; SMU[sdhMsProtectionUnit]; SMG[sdhMsProtectionGroup]; TOP --- PU; TOP --- PG; ELR --- ARR; PU --- SMU; PG --- SMG; end; style CTPS fill:#ccc; style CTPSO fill:#ccc; style CTPB fill:#ccc; style TTPTS fill:#ccc; style TTPTSO fill:#ccc; style TTPTB fill:#ccc; style TOP fill:#ccc; style ELR fill:#ccc; +``` + +Not defined in this Recommendation. + +Inheritance diagrams for SDH MS Protection. The first diagram shows the hierarchy for connection termination points (Sink, Source, Bidirectional) and unprotected CTPs. The second diagram shows the hierarchy for trail termination points (Sink, Source, Bidirectional) and protected TTPs. The third diagram shows the hierarchy for top (X.721) objects like protection unit, protection group, and event log record, leading to sdhMsProtectionUnit, sdhMsProtectionGroup, and apsReportRecord. A legend at the bottom left indicates that shaded boxes are 'Not defined in this Recommendation.' + +**Figure I.1/G.774.3 – SDH MS Protection Inheritance Diagram** + +![SDH MS Protection Naming Diagram showing the hierarchy of elements under sdhNE. The diagram is divided into three main branches: Unprotected CTP, Protected TTP, and SDH MS Protection. The Unprotected CTP branch includes msTTPSource, msTTPSink, msTTPBidirectional, unprotectedCTPSource, unprotectedCTPSink, and unprotectedCTPBidirectional. The Protected TTP branch includes protectedTTPSource, protectedTTPSink, protectedTTPBidirectional, augSource, augSink, and augBidirectional. The SDH MS Protection branch includes sdhMSprotectionGroup, sdhMSprotectionUnit, managedElement (and subclasses, e.g. sdhNE), protectionGroup, and protectionUnit. A legend at the bottom left indicates that elements in grey boxes are not defined in this Recommendation.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +``` + +graph TD + sdhNE[sdhNE] --> msTTPSource[msTTPSource] + sdhNE --> msTTPSink[msTTPSink] + sdhNE --> sdhMSprotectionGroup[sdhMSprotectionGroup] + msTTPSource --> msTTPBidirectional[msTTPBidirectional] + msTTPSink --> msTTPBidirectional + msTTPBidirectional --> unprotectedCTPSource[unprotectedCTPSource] + msTTPBidirectional --> unprotectedCTPSink[unprotectedCTPSink] + unprotectedCTPSource --> unprotectedCTPBidirectional[unprotectedCTPBidirectional] + unprotectedCTPSink --> unprotectedCTPBidirectional + sdhMSprotectionGroup --> sdhMSprotectionUnit[sdhMSprotectionUnit] + sdhMSprotectionUnit --> managedElement["managedElement +(and subclasses, +e.g. sdhNE)"] + managedElement --> protectionGroup[protectionGroup] + protectionGroup --> protectionUnit[protectionUnit] + sdhNE --> protectedTTPSource[protectedTTPSource] + sdhNE --> protectedTTPSink[protectedTTPSink] + protectedTTPSource --> protectedTTPBidirectional[protectedTTPBidirectional] + protectedTTPSink --> protectedTTPBidirectional + protectedTTPBidirectional --> augSource[augSource] + protectedTTPBidirectional --> augSink[augSink] + augSource --> augBidirectional[augBidirectional] + augSink --> augBidirectional + +``` + +SDH MS Protection Naming Diagram showing the hierarchy of elements under sdhNE. The diagram is divided into three main branches: Unprotected CTP, Protected TTP, and SDH MS Protection. The Unprotected CTP branch includes msTTPSource, msTTPSink, msTTPBidirectional, unprotectedCTPSource, unprotectedCTPSink, and unprotectedCTPBidirectional. The Protected TTP branch includes protectedTTPSource, protectedTTPSink, protectedTTPBidirectional, augSource, augSink, and augBidirectional. The SDH MS Protection branch includes sdhMSprotectionGroup, sdhMSprotectionUnit, managedElement (and subclasses, e.g. sdhNE), protectionGroup, and protectionUnit. A legend at the bottom left indicates that elements in grey boxes are not defined in this Recommendation. + +T1514870-94 + +Not defined in this Recommendation. + +**Figure I.2/G.774.3 – SDH MS Protection Naming Diagram** + +## APPENDIX II + +### Examples of MS Protection + +See Figures II.1 to II.6. + +![Diagram of 1 + 1 Linear MS protection, normal case, traffic on channel 1. The diagram shows two parallel channels, channel 0 and channel 1, each with a sequence of network elements: opt-TTP, rs-TTP, ms-TTP, and U-CTP. Channel 1 is active, with traffic passing through a PG (Protection Group) containing two PUs (Protection Units) to a P-TTP, which is then split to an AUG and an AU4-CTP. Channel 0 is idle, with null signals. The diagram includes various pointers: us (Upstream pointer), ds (Downstream pointer), ur (Unreliable resource pointer), rr (Reliable resource pointer), and ccop (Cross-connect object pointer). A legend at the bottom left explains the containment notation (A names B) and defines the pointer types.](329c96049bb432e9c2cbda4e224a0c9c_img.jpg) + +Legend: + +- us Upstream pointer (TP) +- ds Downstream pointer (TP) +- ur Unreliable resource pointer (PU) +- rr Reliable resource pointer (PU) +- ccop Cross-connect object pointer (TP) + +A names B +(commonly called containment). + +T1514880-94 + +Diagram of 1 + 1 Linear MS protection, normal case, traffic on channel 1. The diagram shows two parallel channels, channel 0 and channel 1, each with a sequence of network elements: opt-TTP, rs-TTP, ms-TTP, and U-CTP. Channel 1 is active, with traffic passing through a PG (Protection Group) containing two PUs (Protection Units) to a P-TTP, which is then split to an AUG and an AU4-CTP. Channel 0 is idle, with null signals. The diagram includes various pointers: us (Upstream pointer), ds (Downstream pointer), ur (Unreliable resource pointer), rr (Reliable resource pointer), and ccop (Cross-connect object pointer). A legend at the bottom left explains the containment notation (A names B) and defines the pointer types. + +Figure II.1/G.774.3 – Example of 1 + 1 Linear MS protection, normal case, traffic on channel 1 + +![Diagram of 1+1 Linear MS protection with a failure in channel 1. The diagram shows four parallel processing paths. The top two paths are labeled 'null' and 'us/ds'. The third path is labeled 'channel 1 null' and has a failure symbol (X) on its input. The bottom path is labeled 'channel 0'. Each path consists of blocks: 'opt-TTP', 'rs-CTP', 'rs-TTP', 'ms-CTP', 'ms-TTP', and 'U-CTP'. The 'U-CTP' blocks connect to 'PU' (Protection Unit) blocks, which are part of a 'PG' (Protection Group). The 'PG' blocks connect to 'P-TTP', 'AUG', and 'AU4 CTP' blocks. Arrows indicate traffic flow, with labels like 'ur/ccop', 'ur', 'rr', and 'ccop/rr'. A reference code 'T1514890-94' is in the bottom right.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +Diagram of 1+1 Linear MS protection with a failure in channel 1. The diagram shows four parallel processing paths. The top two paths are labeled 'null' and 'us/ds'. The third path is labeled 'channel 1 null' and has a failure symbol (X) on its input. The bottom path is labeled 'channel 0'. Each path consists of blocks: 'opt-TTP', 'rs-CTP', 'rs-TTP', 'ms-CTP', 'ms-TTP', and 'U-CTP'. The 'U-CTP' blocks connect to 'PU' (Protection Unit) blocks, which are part of a 'PG' (Protection Group). The 'PG' blocks connect to 'P-TTP', 'AUG', and 'AU4 CTP' blocks. Arrows indicate traffic flow, with labels like 'ur/ccop', 'ur', 'rr', and 'ccop/rr'. A reference code 'T1514890-94' is in the bottom right. + +**Figure II.2/G.774.3 – Example of 1 + 1 Linear MS protection, failure of channel 1, traffic switched onto channel 0** + +![Diagram of 1:1 Linear MS protection in a normal case. The diagram shows four parallel processing paths. The top two paths are labeled 'null' and 'us/ds'. The third path is labeled 'channel 1 null'. The bottom path is labeled 'channel 0'. Each path consists of blocks: 'opt-TTP', 'rs-CTP', 'rs-TTP', 'ms-CTP', 'ms-TTP', and 'U-CTP'. The 'U-CTP' blocks connect to 'PU' (Protection Unit) blocks, which are part of a 'PG' (Protection Group). The 'PG' blocks connect to 'P-TTP', 'AUG', and 'AU4 CTP' blocks. Arrows indicate traffic flow, with labels like 'ur/ccop', 'ur', 'rr', and 'ccop/rr'. A reference code 'T1514900-94' is in the bottom right.](95e259e8cb3519025066052af263f8c0_img.jpg) + +Diagram of 1:1 Linear MS protection in a normal case. The diagram shows four parallel processing paths. The top two paths are labeled 'null' and 'us/ds'. The third path is labeled 'channel 1 null'. The bottom path is labeled 'channel 0'. Each path consists of blocks: 'opt-TTP', 'rs-CTP', 'rs-TTP', 'ms-CTP', 'ms-TTP', and 'U-CTP'. The 'U-CTP' blocks connect to 'PU' (Protection Unit) blocks, which are part of a 'PG' (Protection Group). The 'PG' blocks connect to 'P-TTP', 'AUG', and 'AU4 CTP' blocks. Arrows indicate traffic flow, with labels like 'ur/ccop', 'ur', 'rr', and 'ccop/rr'. A reference code 'T1514900-94' is in the bottom right. + +**Figure II.3/G.774.3 – Example of 1:1 Linear MS protection, normal case, no extra traffic** + +![Diagram of 1:1 Linear MS protection with a failure in the working channel (channel 1).](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +This diagram illustrates a 1:1 Linear MS protection scenario where the working channel (channel 1) has failed. The system consists of four horizontal paths representing different channels. The top two paths are labeled 'null' at their left ends. The third path is labeled 'channel 1 null' and has an 'X' mark on its left side, indicating a failure. The bottom path is labeled 'channel 0'. Each path passes through a series of blocks: 'opt-TTP', 'rs-CTP', 'rs-TTP', 'ms-CTP', 'ms-TTP', and 'U-CTP'. On the right side, each 'U-CTP' is connected to a 'PU' (Protection Unit) block, which is further connected to a 'P-TTP' block. Each 'P-TTP' block is associated with an 'AUG' and an 'AU4 CTP' block. Arrows indicate the flow of data and control signals. In this failure scenario, traffic from channel 1 is switched onto the protecting channel (channel 0). Control signals like 'ur/ccop', 'ur', 'us/ds', 'rr', and 'ccop/rr' are shown between the 'U-CTP', 'PU', and 'P-TTP' blocks. A reference code 'T1514910-94' is present in the bottom right corner. + +Diagram of 1:1 Linear MS protection with a failure in the working channel (channel 1). + +**Figure II.4/G.774.3 – Example of 1:1 Linear MS protection, failure of working channel (channel 1), traffic switched onto protecting channel** + +![Diagram of 1:1 Linear MS protection with extra traffic in a normal case.](1ab49904e6a60be337d5b75cb7cc8ab7_img.jpg) + +This diagram illustrates a 1:1 Linear MS protection scenario with extra traffic in a normal case. The system architecture is identical to the previous diagram, with four horizontal paths. The top two paths are labeled 'null'. The third path is labeled 'channel 1 null' and the bottom path is labeled 'channel 0'. Each path passes through the same sequence of blocks: 'opt-TTP', 'rs-CTP', 'rs-TTP', 'ms-CTP', 'ms-TTP', and 'U-CTP'. On the right side, each 'U-CTP' connects to a 'PU', which connects to a 'P-TTP', which in turn connects to an 'AUG' and an 'AU4 CTP' block. In this normal case, both the working channel (channel 1) and the protecting channel (channel 0) carry traffic. The protecting channel (channel 0) carries its own 'Extra Traffic' in addition to the protected traffic from channel 1. Control signals such as 'ur/ccop', 'ur', 'us/ds', 'rr', and 'ccop/rr' are shown. A reference code 'T1514920-94' is present in the bottom right corner. + +Diagram of 1:1 Linear MS protection with extra traffic in a normal case. + +**Figure II.5/G.774.3 – Example of 1:1 Linear MS protection with extra traffic, normal case** + +![Diagram of 1:1 Linear MS protection with extra traffic. It shows two parallel paths: a working path (channel 1) and a protecting path (channel 0). Each path consists of opt-TTP, rs-CTP, rs-TTP, ms-CTP, and ms-TTP/U-CTP blocks. The protecting path carries 'Extra Traffic' and traffic from the failed working channel. Labels include 'null', 'us/ds', 'ur/ccop', 'ccop/rr', 'PG', 'PU', 'P-TTP', 'AUG', and 'AU4 CTP'. Reference T1514930-94 is noted at the bottom right.](798679874d1c29f8343506a156c79d7e_img.jpg) + +T1514930-94 + +Diagram of 1:1 Linear MS protection with extra traffic. It shows two parallel paths: a working path (channel 1) and a protecting path (channel 0). Each path consists of opt-TTP, rs-CTP, rs-TTP, ms-CTP, and ms-TTP/U-CTP blocks. The protecting path carries 'Extra Traffic' and traffic from the failed working channel. Labels include 'null', 'us/ds', 'ur/ccop', 'ccop/rr', 'PG', 'PU', 'P-TTP', 'AUG', and 'AU4 CTP'. Reference T1514930-94 is noted at the bottom right. + +**Figure II.6/G.774.3 – Example of 1:1 Linear MS protection with extra traffic, failure of working channel (channel 1), traffic switched onto protecting channel** + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.774.4-200102-I_PDF-E/raw.md b/marked/G/T-REC-G.774.4-200102-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..d5cacaa68809f48091da1a58e6bd3bdcb524ea11 --- /dev/null +++ b/marked/G/T-REC-G.774.4-200102-I_PDF-E/raw.md @@ -0,0 +1,1825 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.774.4** + +(02/2001) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital terminal equipments – Operations, administration +and maintenance features of transmission equipment + +--- + +**Synchronous digital hierarchy (SDH) – +Management of the subnetwork connection +protection for the network element view** + +ITU-T Recommendation G.774.4 + +(Formerly CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| General | G.700–G.709 | +| Coding of analogue signals by pulse code modulation | G.710–G.719 | +| Coding of analogue signals by methods other than PCM | G.720–G.729 | +| Principal characteristics of primary multiplex equipment | G.730–G.739 | +| Principal characteristics of second order multiplex equipment | G.740–G.749 | +| Principal characteristics of higher order multiplex equipment | G.750–G.759 | +| Principal characteristics of transcoder and digital multiplication equipment | G.760–G.769 | +| Operations, administration and maintenance features of transmission equipment | G.770–G.779 | +| Principal characteristics of multiplexing equipment for the synchronous digital hierarchy | G.780–G.789 | +| Other terminal equipment | G.790–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# **Synchronous digital hierarchy (SDH) – Management of the subnetwork connection protection for the network element view** + +## **Summary** + +This Recommendation provides an information model for the management of subnetwork connection protection of Synchronous Digital Hierarchy (SDH) subnetwork. This model describes the managed object classes and their properties for the subnetwork connection protection function, as defined in ITU-T G.803 and as related to SDH network elements. These objects are useful to describe information exchanged across interfaces defined in M.3010 Telecommunications Management Network (TMN) architecture for the management of the subnetwork connection protection function. + +| Document history | | +|-------------------------|----------------------------------------------------------------------------------| +| Issue | Notes | +| 2001 | First revision incorporated the changes documented in the G.774.4 Corrigendum 1. | +| 7/1995 | Initial version of the Recommendation. | + +###### **Source** + +ITU-T Recommendation G.774.4 was revised by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 9 February 2001. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2002 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. + +# CONTENTS + +###### Page + +| | | | +|------|---------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Terms and Definitions ..... | 3 | +| 4 | Abbreviations..... | 3 | +| 5 | Subnetwork connection protection management model ..... | 4 | +| 5.1 | Overview..... | 4 | +| 5.2 | SDH subnetwork connection protection requirements ..... | 4 | +| 6 | Managed object class definitions..... | 5 | +| 6.1 | Connection protection group ..... | 6 | +| 6.2 | Connection protection..... | 6 | +| 6.3 | Multipoint connection protection..... | 7 | +| 6.4 | Subnetwork connection protection fabric ..... | 9 | +| 7 | Packages..... | 9 | +| 7.1 | Hold off time package..... | 9 | +| 8 | Attributes ..... | 9 | +| 8.1 | Hold off time..... | 9 | +| 8.2 | Protection criteria..... | 10 | +| 8.3 | Switch status ..... | 10 | +| 9 | Actions ..... | 11 | +| 9.1 | Protected connect action ..... | 11 | +| 9.2 | Protect unprotect connection action..... | 12 | +| 10 | Parameters..... | 13 | +| 10.1 | Switch status ..... | 13 | +| 11 | Name bindings ..... | 14 | +| 11.1 | Connection protection..... | 15 | +| 11.2 | Connection protection group R1 ..... | 15 | +| 11.3 | Cross connection..... | 15 | +| 11.4 | Multipoint connection protection..... | 16 | +| 11.5 | Multipoint cross connection..... | 16 | +| 12 | Subordination rules ..... | 16 | +| 13 | Pointer constraints..... | 16 | +| 14 | Supporting ASN.1 productions..... | 16 | + +| | Page | +|-----------------------------------------------------------------------------------------|-------------| +| Annex A – Inheritance and naming diagrams ..... | 19 | +| Annex B – Examples of subnetwork connection protection..... | 21 | +| B.1   Legends ..... | 21 | +| B.2   Subnetwork connection protection examples ..... | 22 | +| B.3   Bidirectional subnetwork connection protection in rings ..... | 28 | +| B.4   Interconnection of protected rings by a cross-connect ..... | 29 | +| B.5   Interconnections of subnetwork with ADMs (SNCP/SNCP) in SNCP interworking | 30 | +| B.6   Logical connections in SNCP interworking rings ..... | 31 | +| B.7   Logical connections in MS SHARED RINGs interworking ..... | 33 | +| B.8   Logical connections in SNCPRing and MS SHARED RING interworking ..... | 35 | +| Annex C – State transition diagrams ..... | 37 | +| C.1   State diagrams ..... | 37 | +| C.2   Allowable values of switchStatus for a protected (mp) connection protection ..... | 37 | +| C.3   Allowable values of switchStatus for a protecting (mp) connection protection..... | 38 | +| C.4   State diagram for a protected connection protection (non-revertive) ..... | 38 | +| C.5   State diagram for a protecting connection protection (non-revertive)..... | 41 | +| C.6   State diagram for a protected connection protection (revertive) ..... | 43 | +| C.7   State diagram for a protecting connection protection (revertive)..... | 45 | + +# **Synchronous digital hierarchy (SDH) – Management of the subnetwork connection protection for the network element view** + +# **1 Scope** + +This Recommendation addresses the management of the automatic protection switching within network element at the high and low order path layers. It covers the subnetwork connection protection as described in ITU-T G.803 and G.841. + +This Recommendation provides an information model, as related to the subnetwork connection protection function for the Synchronous Digital Hierarchy (SDH). It identifies the Telecommunications Management Network (TMN) object classes required for the management of the subnetwork connection protection function for SDH network elements. These objects are relevant to information exchanged across standardized interfaces defined in ITU-T M.3010 TMN architecture. + +This Recommendation applies to SDH network elements which perform the subnetwork connection protection function and those systems in the TMN that manage SDH network elements. + +The new objects defined in this Recommendation supersede those defined in ITU-T G.774.4 (1995). For each object class, attribute, action, notification, parameter defined in this Recommendation it shall be indicated what the impacts upon the existing ITU-T G.774.4 (1995) are. + +## **Structure of this Recommendation** + +Clause 5.1 provides an overview of the SDH subnetwork connection protection information model. Clauses 6-14 describe the information model using the notation mechanisms defined in ITU-T X.722, Guidelines for the Definition of Managed Objects. Clause 14 contains the syntax definitions of the information carried in the protocol using Abstract Syntax Notation One (ASN.1) defined in ITU-T X.680-X.683. Naming and Inheritance are illustrated in Annex A. The state transition diagrams are provided in Annex C. Diagrams illustrating the subnetwork connection protection are provided in Annex B. + +# **2 References** + +The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- ITU-T G.707/Y.1322 (2000), *Network node interface for the synchronous digital hierarchy (SDH)*. +- ITU-T G.773 (1993), *Protocol suites for Q-interfaces for management of transmission systems*. +- ITU-T G.774 (2001), *Synchronous digital hierarchy (SDH) – Management information model for the network element view*. +- ITU-T G.783 (2000), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks*. + +- ITU-T G.784 (1999), *Synchronous digital hierarchy (SDH) management.* +- ITU-T G.803 (2000), *Architecture of transport networks based on the synchronous digital hierarchy (SDH).* +- ITU-T G.831 (2000), *Management capabilities of transport networks based on the synchronous digital hierarchy (SDH).* +- ITU-T G.958 (1994), *Digital line systems based on the synchronous digital hierarchy for use on optical fibre cables.* +- ITU-T M.60 (1993), *Maintenance terminology and definitions.* +- ITU-T M.2120 (2000), *PDH path, section and transmission system and SDH path and multiplex section fault detection and localization procedures.* +- ITU-T M.3010 (2000), *Principles for a telecommunications management network.* +- ITU-T M.3013 (2000), *Considerations for a telecommunications management network.* +- ITU-T M.3100 (1995), *Generic network information model.* +- ITU-T Q.811 (1997), *Lower layer protocol profiles for the Q3 and X interfaces.* +- ITU-T Q.812 (1997), *Upper layer protocol profiles for the Q3 and X interfaces.* +- ITU-T Q.822 (1994), *Stage 1, Stage 2 and Stage 3 description for the Q3-interface – Performance management.* +- ITU-T X.680 to X.683 (1997), *Information technology – Abstract Syntax Notation One (ASN.1).* +- ITU-T X.701 (1997), *Information technology – Open Systems Interconnection – Systems management overview.* +- ITU-T X.710 (1997), *Information technology – Open Systems Interconnection – Common management information service.* +- ITU-T X.711 (1997), *Information technology – Open Systems Interconnection – Common management information protocol: Specification.* +- ITU-T X.720 (1992), *Information technology – Open Systems Interconnection – Structure of Management Information: Management information model, plus Amd.1 (1995) and Cor.1 (1994).* +- ITU-T X.721 (1992), *Information technology – Open Systems Interconnection – Structure for management information: Definition of management information, plus Cor.1 (1994), Cor.2 (1996), Cor.3 (1998) and Cor.4 (2000).* +- ITU-T X.722 (1992), *Information technology – Open Systems Interconnection – Structure of management information: Guidelines for the definition of managed objects, plus Amd.1 (1995), Amd.2 (1997) and Cor.1 (1996).* +- ITU-T X.730 (1992), *Information technology – Open Systems Interconnection – Systems Management: Object management function, plus Amd.1 (1995) and Amd.1/Cor.1 (1996).* +- ITU-T X.731 (1992), *Information technology – Open Systems Interconnection – Systems Management: State management function, plus Amd.1 (1995), Cor.1 (1995) and Amd.1/Cor.1 (1996).* +- ITU-T X.733 (1992), *Information technology – Open Systems Interconnection – Systems Management: Alarm reporting function, plus Cor.1 (1994), Amd.1 (1995), Amd.1/Cor.1 (1996) and Cor.2 (1999).* + +- ITU-T X.734 (1992), *Information technology – Open Systems Interconnection – Systems Management: Event report management function, plus Cor.1 (1994), Amd.1 (1995), Amd.1/Cor.1 (1996) and Cor.2 (1999)*. +- ITU-T X.735 (1992), *Information technology – Open Systems Interconnection – Systems Management: Log control function, plus Amd.1 (1995) and Amd.1/Cor.1 (1996)*. + +# 3 Terms and Definitions + +This Recommendation uses the terms and definitions defined in ITU-T G.774, ITU-T G.784 and ITU-T M.3100. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|-------|----------------------------------------------------------------------------------| +| APDU | Application Protocol Data Unit | +| APS | Automatic Protection Switching | +| BSHR | Bidirectional Self Healing Ring | +| CMIP | Common Management Information Protocol | +| CMIS | Common Management Information Service | +| CTP | Connection Termination Point | +| ISO | International Organization for Standardization | +| ITU-T | International Telecommunication Union – Telecommunication Standardization Sector | +| LOS | Loss Of Signal | +| MS | Multiplex Section | +| MSP | Multiplex Section Protection | +| NE | Network Element | +| OS | Operations System | +| OSI | Open Systems Interconnection | +| Pkg | Package | +| RDN | Relative Distinguished Name | +| RRP | Reliable Resource Pointer | +| SD | Signal Degrade | +| SDH | Synchronous Digital Hierarchy | +| SF | Signal Fail | +| SNCP | Subnetwork Connection Protection | +| STM-N | Synchronous Transport Module N | +| TMN | Telecommunications Management Network | +| TP | Termination Point | +| TTP | Trail Termination Point | +| URP | Unreliable Resource Pointer | + +# 5 Subnetwork connection protection management model + +## 5.1 Overview + +The model is based on those generic classes and modelling principles outlined in ITU-T M.3100 and on those common classes from ITU-T G.774.3. + +It provides a similar way to control and operate the subnetwork connection protection function as the other protection functions. The model defines three subclasses of the generic protection model: + +- connectionProtectionGroupR1 which represents the association of unreliable resources for the purpose of automatic protection switching and which is the focal point for all management operation related to the protection function. +- connectionProtection which represents the protected or the protecting unit and which represents the assignment of an unreliable resource to one reliable resource. The connectionProtection is contained by a connectionProtectionGroupR1. +- mpConnectionProtection used to model protected broadcast. Each leg of the protected broadcast is represented by individual crossConnection contained by the mpConnectionProtection. + +It defines also a subclass of the fabric: sncpFabric derived from the M.3100 fabric. The sncpFabric is used to handle by means of the protectedConnect and protectUnprotect action, in addition to the connect and disconnect actions of the fabric, the following capabilities: + +- Configure protected cross connections using the connection protections and multipoint connection protections. +- Change from unprotected to protected connection without traffic cut. +- Change from protected to unprotected connection without traffic cut. + +## 5.2 SDH subnetwork connection protection requirements + +The management of the subnetwork connection protection function shall provide the following management capabilities: + +- The ability to manage a 1 + 1 single ended subnetwork connection protection for unidirectional and/or bidirectional subnetwork connection. +- The ability to manage the protection of broadcast where all legs are protected altogether and they do not act independently. +- The ability to manage the protection of broadcast where a part of the legs are protected altogether and the other part of the legs are not protected. +- Support of inter-connection of rings using add and drop multiplexer where no interaction between rings exists and where subnetwork connection protection exists in each ring. +- Support of inter-connection of rings using add and drop multiplexer where no interaction between rings exists and where a subnetwork connection protection exists in one ring and a Multiplex Section Shared Protection Ring exists in the other ring. +- Support of inter-connection of rings using add and drop multiplexer where no interaction between rings exists and where a Multiplex Section Shared Protection Ring exists in both rings. +- Support of inter-connection of rings/subnetwork using cross-connections where subnetwork connection protection exists in each ring/subnetwork. +- The ability to configure the protection before activating it. + +- The ability to configure the protection without any traffic flow and to resume the traffic afterwards. +- The ability to change the unreliable (alternate routes) resource while the protection is configured. +- The ability to pass from an existing non-protected connection to a protected connection without traffic cut. +- The ability to pass from a protected connection to an unprotected connection without any traffic cut on the transmit direction. +- The ability to pass from a protected leg of a protected broadcast to an unprotected leg without any traffic cut on the transmit direction. +- The ability to pass from an unprotected leg of a broadcast to a protected leg without any traffic cut. +- The ability when passing from a protected connection to an unprotected connection to select which of the two connections will carry the traffic afterwards. +- The ability to initiate and terminate forced and manual switch. +- The ability to lock out the protected and the protecting connection. +- The ability to suspend and resume the traffic on the protected and the protecting connections. +- The ability to configure the switching criteria. +- The ability to control a switch hold off time and a wait to restore time. +- The ability to configure the protection in a single management operation at each end of the subnetwork connection. +- The ability to add or remove a leg to/from a protected broadcast. +- The network element should not store any historical information about connection configuration before it has been configured in the protection state. + +NOTE – Throughout this Recommendation the terms protecting and protected are used, it is considered that these terms are respectively equivalent to terms used in ITU-T G.841, protection and working, which are no longer used in that Recommendation. + +# 6 Managed object class definitions + +The following object class can be used to model an automatic 1 + 1 single-ended protection system for subnetwork connection protection. + +### Revisions that require re-registration + +This clause provides replacement managed object class definitions for the existing ITU-T G.774.4 (1995). Any managed object class replaced by one in this clause is considered to be deprecated. The reasons for the replacement of a managed object class are as follows: + +- 1) The replaced managed object class is faulty and must be fixed. +- 2) The replaced managed object class includes an attribute, package, notification or action which has been re-registered in this or another Recommendation. +- 3) The replaced managed object class inherits from a managed object class which has been re-registered in this or another Recommendation. + +In each case where a class is replaced, the new class will be registered within this Recommendation. The textual label for the class will be revised to include the text "R1". For example, in the revision of the G.774.4 (1995) managed object class "connectionProtectionGroup", the revised label will become "connectionProtectionGroupR1". + +Below is a table of classes deprecated from ITU-T G.774.4 (1995) and the G.774.4 classes which replace them: + +### *Deprecated G.774.4 (1995) Classes* + +### *Replacement G.774.4 Classes* + +connectionProtectionGroup + +connectionProtectionGroupR1 + +## 6.1 Connection protection group + +``` +connectionProtectionGroupR1 MANAGED OBJECT CLASS +DERIVED FROM "Recommendation G.774.03":protectionGroupR1; +CHARACTERIZED BY + connectionProtectionGroupPkgR1 PACKAGE + BEHAVIOUR connectionProtectionGroupR1Behaviour; + ATTRIBUTES + protectionCriteria GET-REPLACE ADD-REMOVE; + NOTIFICATIONS + "Recommendation G.774.03":protectionSwitchReportingR1 + switchStatusParameter; +CONDITIONAL PACKAGES + holdOffTimePackage +PRESENT IF "an instance supports it"; +REGISTERED AS { g774-04MObjectClass 5 } ; +``` + +``` +connectionProtectionGroupR1Behaviour BEHAVIOUR +DEFINED AS "This object class is used to model an automatic protection +system for subnetwork connection protection. The protectionGroupType attribute +indicates that the protection scheme used is 1+1 (plus). This object class is a +focal point for management operations and notifications related to management of +the protection system. Actual signal flow across the subnetwork connection +protection is reflected by the connectivity pointers of the TPs involved in the +subnetwork connection protection. At instantiation time of an instance of this +class the protectionCriteria attribute is initialized by +local initial value."; +``` + +## 6.2 Connection protection + +``` +connectionProtection MANAGED OBJECT CLASS +DERIVED FROM "Recommendation G.774.03": protectionUnit; +CHARACTERIZED BY + connectionProtectionPkg PACKAGE + BEHAVIOUR connectionProtectionBehaviour; + ATTRIBUTES + switchStatus GET, + "Recommendation X.721": administrativeState GET-REPLACE, + "Recommendation X.721": operationalState GET, + "Recommendation M.3100": signalType GET, + "Recommendation M.3100": directionality GET; + NOTIFICATIONS + "Recommendation X.721": stateChange, + "Recommendation X.721": objectDeletion, + "Recommendation X.721": objectCreation; +REGISTERED AS { g774-04MObjectClass 2 }; +connectionProtectionBehaviour BEHAVIOUR +``` + +``` +DEFINED AS "This object class is used to represent the assignment between +an unreliable resource (TP) and a reliable resource (TP) for the purpose of +subnetwork connection protection. This object class has properties of a cross- +connection since it represents a flexible assignment of termination points in the +context of subnetwork protection, according to Recommendation G.803. The +directionality attribute represents the type of traffic which flows through the +connection protection (CP). It can be either: +``` + +- Bidirectional - The traffic flow is passing between the unreliable and the reliable resource in both directions. + +- Unidirectional - The traffic flow is unidirectional and passing from the unreliable to the reliable resource. + +The Unreliable Resource Pointer (URP) points to one termination point which represents one of the alternatives for the protection system. The URP points to a TP according to the directionality of the CP, i.e.: + +- the URP of a Bidirectional CP must point to a Bidirectional TP or GTP; +- the URP of an Unidirectional CP must point to a Sink TP or GTP, or to a Bidirectional TP or GTP. + +The Unreliable Resource Pointer points to Null when the corresponding (unreliable) TP has been temporarily disconnected from the connection protection. The **crossConnectionObjectPointer** of the corresponding TP points to the **connectionProtection**. + +The Reliable Resource Pointer points either: + +- to Null in the case of a Protecting Connection Protection; or +- to a Termination Point (CTP or TTP) or GTP instance that represents one end of the subnetwork connection in the case of a protected Connection Protection. + +This termination point shall have the same signal type than the CTP or GTP representing the unreliable resource used for protection. + +The **crossConnectionObjectPointer** of the corresponding TP points to the **connectionProtection**. + +The attribute Signal Type describes the signal that is cross-connected. The termination points or GTPs that are cross-connected must have signal types that are compatible. + +If the objects listed in the Unreliable Resource Pointer and Reliable Resource Pointer attributes are GTPs, the nth element of the Unreliable Resource GTP is related to the nth element of the Reliable Resource GTP (for every n). + +#### Administrative state + +- *Unlocked* - The Connection Protection object is administratively unlocked. Traffic is allowed to pass through the Connection Protection. +- *Locked* - No traffic is allowed to pass through the Connection Protection. The traffic flow is suspended between the termination points representing the reliable and the unreliable resources. The connectivity pointers in the corresponding unreliable resources and reliable resources are updated to reflect the suspension of traffic flow. + +Setting the administrative state to locked does not prevent the protection function from attempting to operate. + +#### Operational state + +The operational state reflects only the connection capability of the connection protection: + +- *Enabled* - The Connection Protection is performing its normal cross-connection function. +- *Disabled* - The Connection Protection is incapable of performing its normal cross-connection function. + +The operational state of Disabled is considered as a signal failure on the corresponding connection and as such it must be taken into account in the protection mechanism. + +The **switchStatus** indicates the status of the switching requests."; + +## 6.3 Multipoint connection protection + +``` +mpConnectionProtection MANAGED OBJECT CLASS + DERIVED FROM "Recommendation G.774.03": protectionUnit; + CHARACTERIZED BY + mpConnectionProtectionPkg PACKAGE + BEHAVIOUR mpConnectionProtectionBehaviour; + ATTRIBUTES + switchStatus GET, + "Recommendation X.721": administrativeState GET-REPLACE, + "Recommendation X.721": operationalState GET, + "Recommendation X.721": availabilityStatus GET, +``` + +``` + +"Recommendation M.3100": signalType GET; +NOTIFICATIONS +"Recommendation X.721": stateChange, +"Recommendation X.721": objectDeletion, +"Recommendation X.721": objectCreation;; +REGISTERED AS { g774-04MObjectClass 3 }; +mpConnectionProtectionBehaviour BEHAVIOUR +DEFINED AS "This object class is used to represent the assignment between +an unreliable resource, which is the termination point or GTP object listed in +the Unreliable Resource Pointer attribute, and a set of reliable resources for +the purpose of protection of point-to-multipoint connection. The reliable +resources are the termination point or GTP objects listed in the To Termination +attributes of the crossConnectionmanaged objects contained by protected mp +Connection Protection. +This object class has properties of a multipoint cross-connection since it +represents a flexible assignment of termination points in the context of +subnetwork protection according to Recommendation G.803. +The Unreliable Resource Pointer (URP) points to one termination point or GTP +which represents one of the two alternatives for the protection system. +The URP must point to a Sink CTP or GTP, or to a Bidirectional TP or GTP. +The Unreliable Resource Pointer points to Null when the corresponding +(unreliable) TP has been temporarily disconnected from the multipoint connection +protection. +The crossConnectionObjectPointer of the corresponding TP points to the +mpConnectionProtection. +The Reliable Resource Pointer has always the value NULL. The reliable resources +are represented by all the termination point or GTP objects pointed to by the To +Termination attribute of the crossConnection managed objects contained by the +protected mpConnectionProtection. +The attribute Signal Type describes the signal that is cross-connected. The +termination points or GTPs that are cross-connected must have signal types that +are compatible. + +``` + +### Administrative state + +- *Unlocked* - The Multipoint Connection Protection object is administratively unlocked. It allows traffic to pass through each contained cross-connection depending on its administrative state. +- *Locked* - No traffic is allowed to pass through the Cross-Connection between the cross-connected termination points. The effect of this value overrides the effect of the administrative state of each contained cross-connection. Setting the administrative state to locked does not prevent the protection function from attempting to operate. + +### Operational state + +The operational state of a Multipoint Connection Protection object reflects the overall health of the cross-connection including all the Cross-Connection objects contained in the Multipoint Connection Protection. + +- *Enabled* - The Cross-Connection is performing its normal function. Note that some (but not all) of the cross-connection objects contained in the protected Multipoint Connection Protection may be disabled. +- *Disabled* - The Cross-Connection is incapable of performing its normal cross-connection function. All the cross-connection objects contained in the protected Multipoint Connection Protection are disabled. + +The operational state of Disabled is considered as a signal failure on the corresponding connection and as such it must be taken into account in the protection mechanism. + +### Availability status + +The supported values for this attribute are: + +- *Degraded* - The Multipoint Connection Protection is degraded in some respect. For instance, if one or more (but not all) Cross-Connection objects contained in the protected Multipoint Connection Protection are disabled, the Multipoint Connection Protection will be considered as degraded. The Multipoint Connection Protection remains available for service (i.e. its operational state is enabled) while it is degraded. No automatic protection switch occurs. +- *Empty SET*. + +The **switchStatus** indicates the status of the switching requests." + +## 6.4 Subnetwork connection protection fabric + +``` +sncpFabric MANAGED OBJECT CLASS + DERIVED FROM "Recommendation M.3100": fabric; + CHARACTERIZED BY + sncpFabricPackage PACKAGE + BEHAVIOUR sncpFabricBehaviour; + ACTIONS + protectUnprotect, + protectedConnect;; +REGISTERED AS { g774-04MObjectClass 4 }; +sncpFabricBehaviour BEHAVIOUR + DEFINED AS "The subnetwork connection protection fabric object represents +the function of managing the establishment and release of protected cross- +connections."; +``` + +# 7 Packages + +## 7.1 Hold off time package + +``` +holdOffTimePackage PACKAGE + ATTRIBUTES + holdOffTime GET-REPLACE; +REGISTERED AS { g774-04Package 1 }; +``` + +# 8 Attributes + +## 8.1 Hold off time + +``` +holdOffTime ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHSNCPASN1.HoldOffTime; + MATCHES FOR EQUALITY; + BEHAVIOUR holdOffTimeBehaviour; +REGISTERED AS { g774-04Attribute 1 }; +holdOffTimeBehaviour BEHAVIOUR + DEFINED AS "This attribute specifies the amount of 100 ms periods which +represents the time to wait before performing a protection switch after a defect +has occurred on either the protecting or protected protection unit. The minimum +value is zero (no hold off time) and the maximum value is 100 (representing 10 +seconds). The hold off time is defined in G.841."; +``` + +## 8.2 Protection criteria + +``` +protectionCriteria ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHSNCPASN1.ProtectionCriteria; + MATCHES FOR EQUALITY; + BEHAVIOUR protectionCriteriaBehaviour; +REGISTERED AS { g774-04Attribute 2 }; +protectionCriteriaBehaviour BEHAVIOUR + DEFINED AS "This attribute specifies the list of configurable criteria +that are to be used for automatic switch decision supplementing those criteria +which are defined as mandatory and fixed within the SNCP function as stated in +G.841. "; +``` + +## 8.3 Switch status + +``` +switchStatus ATTRIBUTE + WITH ATTRIBUTE SYNTAX SDHSNCPASN1.ProtectionStatus; + MATCHES FOR EQUALITY; + BEHAVIOUR switchStatusBehaviour; +REGISTERED AS { g774-04Attribute 3 }; +switchStatusBehaviour BEHAVIOUR + DEFINED AS "The following is a list of all the possible status values of +the switchStatus attribute for protected connection protection or protected +mpConnectionProtection: +- No request - There is no outstanding request. An active switch hold off time +is considered a no request. +- Do Not Revert - The protected connection protection has been switched to the +protecting connection protection and the request to do so has been +subsequently cleared. This status is only applicable to 1 + 1 non-revertive +systems. +- Wait-to-Restore - The protected connection protection has recovered from an +auto switch condition and the WTR timer is activated. +- Manual switch to the protecting connection protection completed - The +protected connection protection has been switched to the protecting +connection protection by a manual switch request. +- Auto switch to the protecting connection protection completed - The protected +connection protection has been switched to the protecting connection +protection due to an auto switch condition. +- Auto switch pending - An auto switch request cannot be completed due to +the unavailability of the protecting connection protection. +- Forced switch to the protecting connection protection completed - The +protected connection protection has been forced to switch to the protecting +connection protection. +- Forced switch to the protecting connection protection completed - auto +switch pending - An auto switch request cannot be completed due to a +completed forced switch (to protecting connection protection). +- Lockout of protected connection protection - The protected connection +protection is prevented from switching to protection. +- Lockout of protected connection protection - auto switch pending - An auto +switch request cannot be completed due to the lockout of the protected +connection protection. +``` + +The following is a list of all the possible status values of the **switchStatus** attribute for protecting connection protection or protecting **mpConnectionProtection**: + +- *No request* - There is no outstanding request. An active switch hold off time is considered a no request. +- *Do Not Revert* - The protected connection protection has been switched to the protecting connection protection and the request to do so has been cleared. This status is only applicable to 1 + 1 non-revertive systems. +- *Manual switch to the protecting connection protection completed* - The protected connection protection has been switched to the protecting connection protection by a manual switch request. + +- *Auto switch to the protecting connection protection completed* - A protected connection protection has been switched to the protecting connection protection due to an auto switch condition. +- *Signal fail* - A signal fail condition exists on the protecting connection protection (no traffic is being carried on the protecting connection protection). +- *Forced switch to the protecting connection completed* - The protected connection protection has been forced to switch to the protecting connection protection. +- *Lockout of protection* - The protecting connection protection is prevented from providing protection. +- *Lockout of protection - auto switch condition on protecting connection protection* - A lockout of protection is in place, and an auto switch condition exists on the protecting connection protection."; + +# 9 Actions + +## 9.1 Protected connect action + +``` + +protectedConnect ACTION + BEHAVIOUR protectedConnectBehaviour; + MODE CONFIRMED; + WITH INFORMATION SYNTAX SDHSNCPASN1.ProtectedConnectInformation; + WITH REPLY SYNTAX SDHSNCPASN1.ProtectedConnectResult; +REGISTERED AS { g774-04Action 1 }; +protectedConnectBehaviour BEHAVIOUR + DEFINED AS "This action offers the capability, in a single action, to: +1) Establish a protected connection between termination points/GTPs (connect +Choice of the syntax). The connection to be established is part of a +subnetwork connection protection. The Termination Points/GTP involved in +this protected connection must not be already connected for the concerned +direction. In this case this connection establishment is done according to +the following rules: +- The protecting TP is used to describe the unreliable TP(s) of the +protecting connection. This must be done according to the description +of the protection Connection Type. +- The protection Connection Type is used to describe the type of +connection to be established, i.e. unidirectional or bidirectional. The +protection Connection Type describes the connection between the +unreliable TPs and the reliable TPs for the protected connection. +- If the protection Connection Type is bidirectional, a +connectionProtectionGroupR1 is created. The To TP part of the syntax +represents the reliable resource. +- If the protection Connection Type is unidirectional, it can concern +either: +- A unidirectional point-to-point subnetwork connection protection. +In this case a connectionProtectionGroupR1 is created. +- A unidirectional point-to-multipoint subnetwork connection +protection where all legs are protected altogether. In this case a +connectionProtectionGroupR1 is created, containing: +a) the mpConnectionProtection of the working channel, connecting +the unreliable TP. The reliable TPs are connected by +crossConnection objects contained by the +mpConnectionProtection. +b) the mpConnectionProtection of the protecting channel. This +mpConnectionProtection does not contain crossConnection +object. + +``` + +The administrative state of the created connections objects is specified as an optional parameter of this action. If this parameter is omitted, the administrative state will be set to 'unlocked'. + +- 2) Add TPs/GTPs as destinations of a point-to-multipoint connection. (**addLeg** Choice of the syntax). + - The legs may be added as part of the protected legs (corresponding to the sub-choice protected Legs of the syntax). In that case each **crossConnection** object corresponding to each individual leg is created, these **crossConnections** are contained by the protected **mpConnectionProtection** contained by the **connectionProtectionGroupR1**. + - The legs may be added as non-protected legs (corresponding to the sub-choice unprotected Legs of the syntax). In that case each **crossConnection** object corresponding to each individual leg is created, these **crossConnections** are contained by the **mpCrossConnection** representing the unprotected broadcast. If no unprotected **mpCrossConnection** exists then an **mpCrossConnection** is created, containing all the specified unprotected legs (if only one unprotected leg exists, then a point-to-point unidirectional cross-connection is created). If this action concerns an existing unidirectional point-to-point cross-connection then a point-to-multipoint cross-connection is created which contains the **crossConnections** representing legs. +- The administrative state of the created cross-connection or connection protection objects will be the same as that of the containing multipoint cross-connection or multipoint connection protection object unless otherwise specified in the action parameters. +- 3) Connect a TP as the unreliable resource of an existing protected connection (protected or protecting **connectionProtection** or **mpConnectionProtection** contained in a **connectionProtectionGroupR1**). (**addUnreliable** Choice of the syntax) + - If the specified TP is not already connected for the corresponding direction (**notConnected** sub-choice of the syntax), it will be connected by the specified **connectionProtection** or **mpConnectionProtection**. + - If the specified TP is already connected for the corresponding direction (connected sub-choice of the syntax) by a unidirectional connection (point-to-point or multipoint), the TP will point to the **connectionProtection** or **mpConnectionProtection** in addition to the existing connection(s)."; + +## 9.2 Protect unprotect connection action + +``` + +protectUnprotect ACTION + BEHAVIOUR protectUnprotectBehaviour; + MODE CONFIRMED; + WITH INFORMATION SYNTAX SDHSCNPASN1.ProtectUnprotectInformation; + WITH REPLY SYNTAX SDHSCNPASN1.ProtectedConnectResult; +REGISTERED AS { g774-04Action 2 }; +protectUnprotectBehaviour BEHAVIOUR + DEFINED AS "This action offers the capability, in a single action, to: + +``` + +- 1) Protect an existing unprotected connection (**protect** Choice of the syntax). The description for protecting an existing connection uses the same syntax as the establishment of a new protected connection, and follows the same rules, except that all the TPs or GTP specified in the **protectionConnectionType** part must be explicitly specified by their object instances (i.e. no **tpPool**, no GTP expressed by a sequence of TPs). The connectivity specified by the **protectionConnectionType** part of the syntax must reflect the same connectivity (signal flow expressed by the connectivity pointers) as the existing one, i.e.: + - For a unidirectional point-to-point, the TP specified as the From and the To must be already cross-connected the same way as described and they should not be already protected for the concerned direction. + - For a bidirectional point-to-point, the TPs specified as the from and the To must be already cross-connected the same way as described, i.e.: a bidirectional cross-connection connecting the From TP and the To TP (reliable TP) must already exist. + - For a point-to-multipoint, the TP specified as the From and all the TPs specified as the To must be already cross-connected the same way and none of them should be already part of a protection scheme for the + +concerned direction. Only those legs which are specified as part of the **protectedConnect** Information will be involved in the protection scheme. A **connectionProtectionGroupR1**, two **mpConnectionProtection's** and each **crossConnection** representing each leg are created as the result of this action. If all legs are involved in the protection scheme then the existing **mpCrossConnection** is deleted. The administrative state of the new created connection objects will be the same as that of the existing one they are to replace, unless otherwise specified in the action parameters. The result, if OK is given by the connected Choice of the syntax. + +- 2) Unprotect an existing protected connection (unprotect Choice of the syntax). The description for unprotecting an existing connection uses the same syntax as the establishment of a new unprotected connection, i.e. the **ConnectionType** and **ConnectionTypeBi**, and follows the same rules, except that all the described connections must already exist, and all the TPs or GTP specified in this action must be explicitly specified by their object instances. The connectivity specified by the syntax must reflect the same connectivity as the existing one for either the working or the protect part of the **ConnectionProtectionGroupR1**, i.e.: +- For a unidirectional point-to-point connection protection, the TP specified as the From and the To must be respectively the unreliable TP and the reliable TP of the (protected or protecting) **connectionProtection**. + - For a bidirectional point-to-point, the TPs specified as the From and the To must be respectively the unreliable TP of either the protected or protecting **connectionProtection** and the reliable TP of the protected **connectionProtection**. When the choice single of the syntax is used, a bidirectional cross-connection is created (uniform route) connecting the specified Unreliable TP and the Reliable TP. When the choice multiple of the syntax is used, two unidirectional cross-connections are created (diverse route), one connecting the specified Unreliable TP to the Reliable TP, and the other connecting the Reliable TP to the specified Unreliable TP. + - For a point-to-multipoint, the TP specified as the From and all the TPs specified as the To must be respectively the unreliable TP of the protected mp Connection Protection and the To TPs of the cross-connections contained in the mp connection protection. If TPs are specified which do not pertain to the protection scheme, the requests fail with the logical problem mismatching TP Instances. Only those TPs which are explicitly specified as part of the **protectedUnprotectInformation** will be unprotected, and if no **mpCrossConnection** was already existing then one is created which holds each **crossConnection** corresponding to each unprotected leg. If no other TP remains in the protected scheme, then the **connectionProtectionGroupR1** is deleted and consequently all its contained objects. The administrative state of the new created connection objects will be the same as that of the existing one they are to replace, unless otherwise specified in the action parameters."; + +# 10 Parameters + +## 10.1 Switch status + +``` + +switchStatusParameter PARAMETER + CONTEXT EVENT-INFO; + WITH SYNTAX SDHSNCPASN1.ProtectionStatusParameter; + BEHAVIOUR switchStatusParameterBeh; +REGISTERED AS { g774-04Parameter 1 }; +switchStatusParameterBeh BEHAVIOUR + DEFINED AS "This parameter is included in the additional info parameters +of the protection switching reporting notification. This notification is sent by +the protection group according to the following rules. There are several cases: + +``` + +- The switch from protected to protecting or protecting to protected has been done without preempting an existing switch. In this case, the old and new values of the Switch status attribute of the protecting channel shall be reported in the notification by means of the **oldSwitchStatus** and **newSwitchStatus** parameters respectively. +- A switch is performed by preempting an exiting one. In this case, the old and new values of the Switch status attribute of the protecting channel shall be reported in the notification by means of the **oldSwitchStatus** and **newSwitchStatus** parameters respectively. +- An auto switch condition exists on a channel but the auto switch cannot be served due to the unavailability of the channel that otherwise protects it. In this case the **oldSwitchStatus** and **newSwitchStatus** parameters refer to the switch status attribute value of the channel on which the auto switch condition arises. The exception is when the channel is already forced or locked out, in which case no notification is sent. +- A working channel (protected unit) has been locked out or released from lockout without modifying any existing switch. In this case the **oldSwitchStatus** and **newSwitchStatus** parameters refer to the switch status attribute value of the working channel which has been locked out. +- A protection channel (protecting unit) has been locked out or released from lockout without modifying the existing switch. In this case, the **oldSwitchStatus** and **newSwitchStatus** parameters refer to the switch status attribute value of the protection channel which has been locked out. + +The **protectionSwitchReporting** is not sent when the automatic switch condition is toggling between SF and WTR condition. While in the lockout of forced switch state no notification is sent except for ending of release failure."; + +# 11 Name bindings + +### Revisions that require re-registration + +This clause provides replacement namebinding definitions for the existing ITU-T G.774.4 (1995). Any namebinding replaced by one in this clause is considered to be deprecated. The reasons for the replacement of a namebinding are as follows: + +- 1) The replaced namebinding is faulty and must be fixed. +- 2) The replaced namebinding refers to a superior managed object class which has been re-registered in this or another Recommendation. +- 3) The replaced namebinding refers to a subordinate managed object class which has been re-registered in this or another Recommendation. +- 4) The replaced namebinding refers to a naming attribute which has been re-registered in this or another Recommendation. + +In each case where a namebinding is replaced, the new namebinding will be registered within this Recommendation. The textual label for the namebinding will be revised to include the text "R1". For example, in the revision of the G.774.4 (1995) namebinding "connectionProtection-connectionProtectionGroup", the revised label will become "connectionProtection-connectionProtectionGroupR1". Note the "R1" is placed immediately following the revised class which impacts the namebinding. + +Below is a table of namebindings deprecated from ITU-T G.774.4 (1995) and the G.774.4 namebindings which replace them: + +### *Deprecated G.774.4 (1995) Namebindings* + +connectionProtection-connectionProtectionGroup +connectionProtectionGroup-sncpFabric +mpConnectionProtection-connectionProtectionGroup + +### Replacement G.774.4 Namebindings + +connectionProtection-connectionProtectionGroupR1 +connectionProtectionGroupR1-sncpFabric +mpConnectionProtection-connectionProtectionGroupR1 + +## 11.1 Connection protection + +``` +connectionProtection-connectionProtectionGroupR1 NAME BINDING + SUBORDINATE OBJECT CLASS connectionProtection AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS connectionProtectionGroupR1 + AND SUBCLASSES; + WITH ATTRIBUTE "Recommendation G.774.03":protectionUnitId; + BEHAVIOUR + connectionProtection-connectionProtectionGroupR1Beh BEHAVIOUR + DEFINED AS "The connection protection is contained by a +connection protection Group managed object instance. There must be two and only +two CP (Connection Protection) in the CPG (Connection Protection Group), with the +same signal type and the same directionality. This is used to represent a +point-to-point unidirectional or bidirectional connection protection. One of +these CPs must be the protected one (protecting attribute with the value +'FALSE'), and the other must be the protecting one (protecting attribute with the +value 'TRUE')." ; +REGISTERED AS { g774-04NameBinding 7 } +; +``` + +## 11.2 Connection protection group R1 + +``` +connectionProtectionGroupR1-sncpFabric NAME BINDING + SUBORDINATE OBJECT CLASS + connectionProtectionGroupR1 AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS + sncpFabric AND SUBCLASSES; + WITH ATTRIBUTE "Recommendation G.774.03":protectionGroupId; + BEHAVIOUR connectionProtectionGroupR1-sncpFabricBeh BEHAVIOUR + DEFINED AS "A Connection Protection Group is created as the +result of the establishment of a protected connection (point-to-point or point- +to-multipoint) or of the protection of an existing non-protected connection. When +disconnecting a TP involved in a protected connection: +- if the TP is the reliable resource of a point-to-point connection +protection, or the last reliable resource (last leg) of a multipoint +connection protection, this leads to the disconnection of the protection, +resulting in the deletion of the connection protection group and all +contained objects. +- if the TP is the unreliable resource of a connection protection or +multipoint connection protection, the corresponding Unreliable Resource +Pointer is set to NULL. Such a disconnection shall be considered as a signal +failure. A new unreliable resource (TP) may be connected using the +capability to add a new unreliable resource of the protected connect action. +When both unreliable TPs are disconnected, this leads to the disconnection +of the protection, resulting in the deletion of the connection protection +group and all contained objects. " ; +REGISTERED AS { g774-04NameBinding 8 }; +``` + +## 11.3 Cross connection + +``` +crossConnection-mpConnectionProtection NAME BINDING + SUBORDINATE OBJECT CLASS "Recommendation M.3100": +crossConnection AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS mpConnectionProtection AND SUBCLASSES; + WITH ATTRIBUTE "Recommendation M.3100":crossConnectionId; + DELETE ONLY-IF-NO-CONTAINED-OBJECTS; +REGISTERED AS { g774-04NameBinding 3 }; +``` + +``` + +crossConnection-sncpFabric NAME BINDING + SUBORDINATE OBJECT CLASS "Recommendation M.3100": +crossConnection AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS sncpFabric AND SUBCLASSES; + WITH ATTRIBUTE "Recommendation M.3100":crossConnectionId; + DELETE ONLY-IF-NO-CONTAINED-OBJECTS; +REGISTERED AS { g774-04NameBinding 5 }; + +``` + +## 11.4 Multipoint connection protection + +``` + +mpConnectionProtection-connectionProtectionGroupR1 NAME BINDING + SUBORDINATE OBJECT CLASS mpConnectionProtection AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS + connectionProtectionGroupR1 AND SUBCLASSES; + WITH ATTRIBUTE1 "Recommendation G.774.03":protectionUnitId; + BEHAVIOUR mpConnectionProtection-connectionProtectionGroupR1Beh + BEHAVIOUR + DEFINED AS "MultiPoint Connection Protection are created as +the result of the establishment of a protected multipoint connection or of the +protection of an existing non-protected multipoint connection. The multipoint +connection protections are contained directly by the connection protection Group +managed object instance. There must be two and only two mpConnectionProtections +in the connectionProtectionGroup, with the same signal type. This is used to +represent the point to multipoint unidirectional connection protection. +One of these mpConnectionProtection must be the protected one (protecting +attribute with the value FALSE), and the other must be the protecting one +(protecting attribute with the value TRUE). +Only the protected mpConnectionProtection can contain cross-connections +representing the reliable resources. The configuration may be done prior to any +existing cross-connection or on an existing multipoint cross-connection." ; ; +REGISTERED AS { g774-04NameBinding 9 }; + +``` + +## 11.5 Multipoint cross connection + +``` + +mpCrossConnection-sncpFabric NAME BINDING + SUBORDINATE OBJECT CLASS "Recommendation M.3100": +mpCrossConnection AND SUBCLASSES; + NAMED BY SUPERIOR OBJECT CLASS sncpFabric AND SUBCLASSES; + WITH ATTRIBUTE "Recommendation M.3100":mpCrossConnectionId; +REGISTERED AS { g774-04NameBinding 6 }; + +``` + +# 12 Subordination rules + +None. + +# 13 Pointer constraints + +None. + +# 14 Supporting ASN.1 productions + +``` + +SDHSCNPASN1 { itu-t(0) recommendation(0) g(7) g774(774) hyphen(127) sncp(04) +informationModel(0) asnlModule(2) sdhscnp (0) } +DEFINITIONS IMPLICIT TAGS ::= +BEGIN + -- EXPORTS everything -- + IMPORTS + ObjectInstance + FROM CMIP-1 { joint-iso-ccitt ms(9) cmip(1) modules(0) protocol(3) } + +``` + +``` + +AdministrativeState, OperationalState +FROM Attribute-ASN1Module { joint-iso-ccitt ms(9) smi(3) part2(2) asn1Module(2) 1 +} +AddLeg, Connected, ConnectionType, ConnectionTypeBi, Directionality, +ExplicitPtoMP, +ExplicitPtoP, ExplicitTP, Failed, PointToMultipoint, PointToPoint, PtoMPools, +PtoTPPool +FROM ASN1DefinedTypesModule { ccitt recommendation m(13) gnm(3100) +informationModel(0) asn1Modules(2) asn1DefinedTypesModule(0) } +Boolean, Integer, ProtectionStatus, ProtectionStatusParameter +FROM SDHProtASN1 { itu-t(0) recommendation(0) g(7) g774(774) hyphen(127) prot(03) +informationModel(0) asn1Module(2) sdhmsp(0) }; +sdhSNCP OBJECT IDENTIFIER ::= { itu-t(0) recommendation(0) g(7) g774(774) +hyphen(127) +sncp(04) informationModel(0) } +g774-04MObjectClass OBJECT IDENTIFIER ::= { sdhSNCP managedObjectClass(3) } +g774-04Attribute OBJECT IDENTIFIER ::= { sdhSNCP attribute(7) } +g774-04Action OBJECT IDENTIFIER ::= { sdhSNCP action(9) } +g774-04NameBinding OBJECT IDENTIFIER ::= { sdhSNCP nameBinding(6) } +g774-04Parameter OBJECT IDENTIFIER ::= { sdhSNCP parameter(5) } +g774-04Package OBJECT IDENTIFIER ::= { sdhSNCP package(4) } +g774-04StandardSpecificExtension OBJECT IDENTIFIER ::= { sdhSNCP +standardSpecificExtension(0) } +-- The following value assignments are for the Protection Criteria in the +-- context of SDH. +-- These values shall always be assigned by this Recommendation in the context +-- of SDH. +sncpProtectionCriteria OBJECT IDENTIFIER ::= +{ g774-04StandardSpecificExtension 0 } +sncpPathTraceMismatchCriteria OBJECT IDENTIFIER ::= { sncpProtectionCriteria 1 } +sncpExcessiveErrorCriteria OBJECT IDENTIFIER ::= { sncpProtectionCriteria 2 } +ConnectUnreliableTP ::= CHOICE { + notConnected [0] UnreliableTp, + connected [1] UnreliableTp +} +HoldOffTime ::= INTEGER +PointToPointProtection ::= SEQUENCE { + protectedPointToPoint PointToPoint, + protectingPointToPoint ProtectingConnection +} +-- The object Instance of the xCon of PointToPoint represents the object +-- instance of the created connectionProtection +PointToMultipointProtection ::= SEQUENCE { + protectedPointToMultipoint PointToMultipoint, + protectingPointToMultipoint ProtectingConnection +} +-- The object Instance of the xConnections and mpXCon of PointToMultipoint +-- represents the object instances of the created crossConnections and +-- mpConnectionProtection +-- The protectingPointToMultipoint represents the object instance of the +-- unreliable TP and the object instance of the created mpConnectionProtection +-- of the protecting connection +ProtectedAddLeg ::= CHOICE { + protected [0] AddLeg, + unProtected [1] AddLeg +} +-- The object Instance of the mpXCon of AddLeg represents the object instance of +-- the mpConnectionProtection to which new legs are added + +``` + +``` + +ProtectedConnectInformation ::= SEQUENCE OF SEQUENCE { + CHOICE { + connect [0] ProtectedConnection, + addleg [1] ProtectedAddLeg, + addUnreliable [2] ConnectUnreliableTP + }, + administrativeState AdministrativeState OPTIONAL +} +ProtectedConnection ::= SEQUENCE { + protectionConnectionType ProtectionConnectionType, + protectingTP ExplicitTP, + revertive Boolean, + waitToRestore [0] Integer OPTIONAL, + holdOffTime [1] HoldOffTime OPTIONAL +} +ProtectionConnectionType ::= CHOICE { + unidirectional [0] ConnectionType, + bidirectional [1] ConnectionTypeBi +} +ProtectedConnectionResult ::= SEQUENCE { + CHOICE { + pointToPoint [0] PointToPointProtection, + pointToMultipoint [1] PointToMultipointProtection + }, + connectionPG ObjectInstance +} +ProtectedConnectResult ::= SEQUENCE OF CHOICE { + failed [0] Failed, + protected [1] ProtectedConnectionResult, + unprotected [2] Unprotected +} +-- the n-th element in the "SEQUENCE OF" is related to the n-th element in the +-- "SEQUENCE OF" of the "ProtectedConnectInformation" type. +ProtectingConnection ::= SEQUENCE { + unreliableTp ObjectInstance, + conProt ObjectInstance +} +ProtectionCriteria ::= SET OF Criterion +Criterion ::= OBJECT IDENTIFIER +ProtectUnprotectInformation ::= SEQUENCE OF SEQUENCE { + CHOICE { + protect [3] ProtectedConnection, + unprotect [4] UnprotectConnection + }, + administrativeState AdministrativeState OPTIONAL +} +Unprotected ::= CHOICE { + uniform [0] Connected, + divers [1] UnprotectedMultiple +} +UnprotectedMultiple ::= SEQUENCE { + sending PointToPoint, + receiving PointToPoint +} +UnprotectConnection ::= CHOICE { + uniPToP [0] ExplicitPtoP, + pToMp [1] ExplicitPtoMP, + bidirectional [2] UnprotectBi +} +UnprotectBi ::= CHOICE { + uniformRoute [0] ExplicitPtoP, + diverseRoute [1] UnprotectMultiple +} + +``` + +``` + +UnprotectMultiple ::= SEQUENCE { + firstXCon ExplicitPtoP, + secondXCon ExplicitPtoP +} +UnreliableTp ::= SEQUENCE { + unreliableTp ExplicitTP, + connectionProtection ObjectInstance +} +END + +``` + +# ANNEX A + +## Inheritance and naming diagrams + +![Inheritance subtree diagram for subnetwork connection protection. The hierarchy starts with 'top' at the root, which branches into 'protectionGroup', 'protectionUnit', and 'Fabric'. 'protectionGroup' branches into 'crossConnection' and 'connectionProtection Group'. 'protectionUnit' branches into 'mpCrossConnection' and 'connectionProtection'. 'Fabric' branches into 'sncpFabric'. Each of 'connectionProtection Group', 'connectionProtection', and 'sncpFabric' has a 'B' diamond with a downward arrow, indicating further inheritance or naming.](26d664119ad25250780f554633444e54_img.jpg) + +``` + +graph TD + top[top] --> B1{B} + B1 --> PG[protectionGroup] + B1 --> PU[protectionUnit] + B1 --> F[Fabric] + PG --> CC[crossConnection] + PG --> CPG[connectionProtection Group] + PU --> MCP[mpCrossConnection] + PU --> CP[connectionProtection] + F --> SF[sncpFabric] + CPG --> B2{B} + CP --> B3{B} + SF --> B4{B} + B2 --> CPG_desc[ ] + B3 --> CP_desc[ ] + B4 --> SF_desc[ ] + style CPG_desc fill:none,stroke:none + style CP_desc fill:none,stroke:none + style SF_desc fill:none,stroke:none + +``` + +Inheritance subtree diagram for subnetwork connection protection. The hierarchy starts with 'top' at the root, which branches into 'protectionGroup', 'protectionUnit', and 'Fabric'. 'protectionGroup' branches into 'crossConnection' and 'connectionProtection Group'. 'protectionUnit' branches into 'mpCrossConnection' and 'connectionProtection'. 'Fabric' branches into 'sncpFabric'. Each of 'connectionProtection Group', 'connectionProtection', and 'sncpFabric' has a 'B' diamond with a downward arrow, indicating further inheritance or naming. + +T1517020-94 + +Figure A.1/G.774.4 – Inheritance subtree of subnetwork connection protection + +![Containment tree of the subnetwork connection protection diagram showing hierarchy from sdhNE down to crossConnections via fabric, sncpFabric, mpCrossConnection, connectionProtectionGroup, and mpConnectionProtection components.](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg) + +``` + +graph TD + sdhNE[sdhNE] -- C --> fabric[fabric] + sdhNE -- C --> sncpFabric[sncpFabric] + fabric -- C --> crossConnection1[crossConnection] + fabric -- C --> mpCrossConnection[mpCrossConnection] + sncpFabric -- C --> crossConnection1 + sncpFabric -- C --> connectionProtectionGroup[connectionProtectionGroup] + mpCrossConnection -- C --> crossConnection2[crossConnection] + connectionProtectionGroup -- C --> connectionProtection[connectionProtection] + connectionProtectionGroup -- C --> mpConnectionProtection[mpConnectionProtection] + mpConnectionProtection -- C --> crossConnection3[crossConnection] + +``` + +T1517030-94 + +Containment tree of the subnetwork connection protection diagram showing hierarchy from sdhNE down to crossConnections via fabric, sncpFabric, mpCrossConnection, connectionProtectionGroup, and mpConnectionProtection components. + +**Figure A.2/G.774.4 – Containment tree of the subnetwork connection protection** + +# ANNEX B + +## Examples of subnetwork connection protection + +### B.1 Legends + +In the following figures, the following legends and symbols will be used as described in Figure B.1. + +| Legend | | | | +|--------|---------------------------------------------|-------|---------------------------| +| | U-Pd: Unidirectional Protected | U-Pg: | Unidirectional Protecting | +| | B-Pd: Bidirectional Protected | B-Pg: | Bidirectional Protecting | +| | Naming | | | +| → | Downstream connectivity pointer | | | +| → | RRP Reliable Resource Pointer | | | +| → | COP Cross Connection Object Ptr | | | +| → | DCOP Downstream Cross Connection Object Ptr | | | +| → | UCOP Upstream Cross Connection Object Ptr | | | +| → | Upstream connectivity pointer | | | +| → | URP Unreliable Resource Pointer | | | +| → | To TP | | | +| → | From TP | | | + +T1517040-94 + +Figure B.1/G.774.4 – Legend + +## B.2 Subnetwork connection protection examples + +See Figures B.2 to B.7. + +![Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains TPA, XC, and TPA1. NE-B contains TPB1, XC, and TPB. A solid line with arrows shows signal flow from TPA1 to TPB1. A dashed line represents the subnetwork connection between TPA1 and TPB1.](b235edb1dbe659e2782c9a0e47775ca4_img.jpg) + +Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains TPA, XC, and TPA1. NE-B contains TPB1, XC, and TPB. A solid line with arrows shows signal flow from TPA1 to TPB1. A dashed line represents the subnetwork connection between TPA1 and TPB1. + +a) Non-protected unidirectional subnetwork connection between NE-A and NE-B + +![Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains TPA, MPXC, XC (C), TPA1, XC, and TPA2. NE-B contains TPB1, CPG (CPr U-Pd), TPB, TPB2, and CPG (CPr U-Pg). Signal flow is shown from TPA to TPA1 and TPA2, then through protected and protecting subnetwork connections to TPB1 and TPB2, and finally to TPB. NULL connections are shown from TPB2 and CPr U-Pg.](eb5677b570ab2a3e9d8f5d35ca5b8a4d_img.jpg) + +Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains TPA, MPXC, XC (C), TPA1, XC, and TPA2. NE-B contains TPB1, CPG (CPr U-Pd), TPB, TPB2, and CPG (CPr U-Pg). Signal flow is shown from TPA to TPA1 and TPA2, then through protected and protecting subnetwork connections to TPB1 and TPB2, and finally to TPB. NULL connections are shown from TPB2 and CPr U-Pg. + +b) Protected unidirectional subnetwork connection between NE-A and NE-B + +T1517050-94 + +**Figure B.2/G.774.4 – Unidirectional cross-connection and connection protection modeled at the transmit end as a normal broadcast and at the receiving end by connection protection group** + +![Diagram (a) showing a non-protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains XC, TPA, and TPA1. NE-B contains XC, TPB1, and TPB. A dashed line labeled 'Subnetwork Connection' connects TPA1 and TPB1. Signal flow is indicated by a double-headed arrow above the connection.](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg) + +Diagram (a) showing a non-protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains XC, TPA, and TPA1. NE-B contains XC, TPB1, and TPB. A dashed line labeled 'Subnetwork Connection' connects TPA1 and TPB1. Signal flow is indicated by a double-headed arrow above the connection. + +a) Non-protected bidirectional subnetwork connection between NE-A and NE-B + +![Diagram (b) showing a protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains two CPG units: one with CPr B-Pd (connected to TPA) and one with CPr B-Pg (connected to TPA2). NE-B contains two CPG units: one with C-Pr B-Pd (connected to TPB1) and one with CPr B-Pg (connected to TPB2). A 'Protected Subnetwork Connection' (dashed line) connects TPA to TPB1, and a 'Protecting Subnetwork Connection' (dashed line) connects TPA2 to TPB2. Signal flow is indicated by a double-headed arrow between the two connections. NULL pointers are shown at the bottom of each node.](dcb5711d118ae6753b0e12f86eda37db_img.jpg) + +Diagram (b) showing a protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains two CPG units: one with CPr B-Pd (connected to TPA) and one with CPr B-Pg (connected to TPA2). NE-B contains two CPG units: one with C-Pr B-Pd (connected to TPB1) and one with CPr B-Pg (connected to TPB2). A 'Protected Subnetwork Connection' (dashed line) connects TPA to TPB1, and a 'Protecting Subnetwork Connection' (dashed line) connects TPA2 to TPB2. Signal flow is indicated by a double-headed arrow between the two connections. NULL pointers are shown at the bottom of each node. + +b) Protected bidirectional subnetwork connection between NE-A and NE-B + +T1517060-94 + +Figure B.3/G.774.4 – Bidirectional cross-connection and connection protection (uniform route) + +![Diagram (a) showing non-protected bidirectional subnetwork connection diverse route between NE-A and NE-B. NE-A contains XC, TPA, TPA1, NULL, TPA2, and XC. NE-B contains XC, TPB1, NULL, TPB2, NULL, and XC. Signal flow is indicated by arrows between the two networks.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg) + +Diagram (a) illustrates a non-protected bidirectional subnetwork connection diverse route between NE-A and NE-B. NE-A is a box containing two XC (Cross-Connection) blocks, a TPA block on the left, and TPA1 and TPA2 blocks on the right. Arrows connect TPA to both XCs, and both XCs to TPA1 and TPA2. TPA1 and TPA2 also have arrows pointing to NULL terminations. NE-B is a similar box with TPB on the right, TPB1 and TPB2 on the left, and two XC blocks. Dashed lines labeled 'Subnetwork Connections' connect TPA1 to TPB1 and TPA2 to TPB2. Large arrows indicate 'Signal Flow' in both directions between the NEs. + +Diagram (a) showing non-protected bidirectional subnetwork connection diverse route between NE-A and NE-B. NE-A contains XC, TPA, TPA1, NULL, TPA2, and XC. NE-B contains XC, TPB1, NULL, TPB2, NULL, and XC. Signal flow is indicated by arrows between the two networks. + +a) **Non-protected bidirectional subnetwork connection diverse route between NE-A and NE-B** + +![Diagram (b) showing protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains TPA, CPG (with CPr B-Pd and CPr B-Pg), TPA2, NULL, TPA1, and NULL. NE-B contains TPB1, CPG (with CPr B-Pd and CPr B-Pg), TPB2, NULL, and NULL. Protected and protecting subnetwork connections are shown between the networks.](fa01531ea2c45beeb4036005da3037a4_img.jpg) + +Diagram (b) illustrates a protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA block connected to a CPG (Connection Protection Group) box. Inside CPG are two blocks: CPr B-Pd and CPr B-Pg. CPr B-Pd connects to TPA2, and CPr B-Pg connects to TPA1. Both TPA1 and TPA2 have arrows pointing to NULL terminations. NE-B has a mirrored structure with TPB, a CPG (containing CPr B-Pd and CPr B-Pg), TPB1, and TPB2. A dashed line labeled 'Protected Subnetwork Connection' connects TPA2 to TPB1. Another dashed line labeled 'Protecting Subnetwork Connection' connects TPA1 to TPB2. A double-headed arrow indicates 'Signal Flow'. + +Diagram (b) showing protected bidirectional subnetwork connection between NE-A and NE-B. NE-A contains TPA, CPG (with CPr B-Pd and CPr B-Pg), TPA2, NULL, TPA1, and NULL. NE-B contains TPB1, CPG (with CPr B-Pd and CPr B-Pg), TPB2, NULL, and NULL. Protected and protecting subnetwork connections are shown between the networks. + +b) **Protected bidirectional subnetwork connection between NE-A and NE-B** + +**Figure B.4/G.774.4 – Cross-connection and connection protection (diverse route)** + +![Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, XC, and TPA1. NE-B contains TPB1, MPXC, three XC units, and TPBX, TPBY, TPBZ. Signal flow is from NE-A to NE-B.](c494cd874a082a97b50b3c4d3938f467_img.jpg) + +Diagram (a) illustrates a non-protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA, an XC, and a TPA1. NE-B contains a TPB1, an MPXC, three XC units, and three TPB units (TPBX, TPBY, TPBZ). The connection is unidirectional, with signal flow from NE-A to NE-B. The connection is labeled 'Subnetwork Connection' and 'Signal Flow'. + +Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, XC, and TPA1. NE-B contains TPB1, MPXC, three XC units, and TPBX, TPBY, TPBZ. Signal flow is from NE-A to NE-B. + +a) Non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B + +![Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, MPXC, two XC units, and TPA1, TPA2. NE-B contains TPB1, CPG (with MPCP U-Pd and MPCP U-Pg), three XC units, and TPBX, TPBY, TPBZ. Signal flow is from NE-A to NE-B.](dcf37c460c66ec011dbe6ca08de44ff9_img.jpg) + +Diagram (b) illustrates a protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA, an MPXC, two XC units, and two TPA units (TPA1, TPA2). NE-B contains a TPB1, a CPG (containing MPCP U-Pd and MPCP U-Pg), three XC units, and three TPB units (TPBX, TPBY, TPBZ). The connection is unidirectional, with signal flow from NE-A to NE-B. The connection is labeled 'Protected Subnetwork Connection' and 'Signal Flow'. The connection is also labeled 'Protecting Subnetwork Connection'. + +Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, MPXC, two XC units, and TPA1, TPA2. NE-B contains TPB1, CPG (with MPCP U-Pd and MPCP U-Pg), three XC units, and TPBX, TPBY, TPBZ. Signal flow is from NE-A to NE-B. + +b) Protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B + +T1517080-94 + +Figure B.5/G.774.4 – Unidirectional upstream point-to-multipoint cross-connection and connection protection (All the legs (TPBX, TPBY and TPBZ) are protected as a whole) + +![Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, XC, and TPA1. NE-B contains MPXC, TPB1, XC, TPBX, TPBY, and TPBZ. Signal flow is from NE-A to NE-B.](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +Diagram (a) illustrates a non-protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA connected to an XC, which is connected to TPA1. A subnetwork connection (dashed line) links TPA1 to NE-B. In NE-B, the connection enters TPB1, which is connected to an MPXC. The MPXC is connected to three XCs, which are in turn connected to TPBX, TPBY, and TPBZ respectively. Signal flow is indicated by arrows pointing from NE-A to NE-B. + +Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, XC, and TPA1. NE-B contains MPXC, TPB1, XC, TPBX, TPBY, and TPBZ. Signal flow is from NE-A to NE-B. + +a) Non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B + +![Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, MPXC, XC, TPA1, and TPA2. NE-B contains TPB1, XC, CPG, MPCP U-Pd, TPBX, TPBY, TPBZ, TPB2, and MPCP U-Pg. Signal flow is from NE-A to NE-B. Protection is provided for legs TPBY and TPBZ.](14252bcd35912bd656e98b16b2ee51c0_img.jpg) + +Diagram (b) illustrates a protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA connected to an MPXC, which is connected to two XCs, which are in turn connected to TPA1 and TPA2 respectively. A protected subnetwork connection (dashed line) links TPA1 to NE-B. In NE-B, the connection enters TPB1, which is connected to an XC. The XC is connected to a CPG (containing MPCP U-Pd), which is connected to two XCs, which are in turn connected to TPBY and TPBZ respectively. A protecting subnetwork connection (dashed line) links TPA2 to TPB2, which is connected to an MPCP U-Pg. Signal flow is indicated by arrows pointing from NE-A to NE-B. The protection is provided for legs TPBY and TPBZ. + +Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains TPA, MPXC, XC, TPA1, and TPA2. NE-B contains TPB1, XC, CPG, MPCP U-Pd, TPBX, TPBY, TPBZ, TPB2, and MPCP U-Pg. Signal flow is from NE-A to NE-B. Protection is provided for legs TPBY and TPBZ. + +b) Protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B + +T1517090-94 + +Figure B.6/G.774.4 – Unidirectional upstream point-to-multipoint cross-connection and connection protection (Only the legs TPBY and TPBZ are protected) + +![Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains a TPA block connected to an XC block, which connects to a TPA1 block. A 'Subnetwork Connection' line connects TPA1 in NE-A to TPB1 in NE-B. NE-B contains an MPXC block at the top, which controls four XC blocks. TPB1 distributes the signal to these four XC blocks. Each XC block then connects to a corresponding termination point: TPBW, TPBX, TPBY, and TPBZ. Signal flow is indicated by a large arrow pointing right. Right arrow](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +Diagram (a) illustrates a non-protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA, an XC, and a TPA1. NE-B contains an MPXC, a TPB1, and multiple XC units connected to TPBW, TPBX, TPBY, and TPBZ. Signal flow is indicated by arrows pointing from NE-A to NE-B. + +Signal Flow + +Subnetwork Connection + +Diagram (a) showing a non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A contains a TPA block connected to an XC block, which connects to a TPA1 block. A 'Subnetwork Connection' line connects TPA1 in NE-A to TPB1 in NE-B. NE-B contains an MPXC block at the top, which controls four XC blocks. TPB1 distributes the signal to these four XC blocks. Each XC block then connects to a corresponding termination point: TPBW, TPBX, TPBY, and TPBZ. Signal flow is indicated by a large arrow pointing right. Right arrow + +**a) Non-protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B** + +![Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A now includes an MPXC and two output termination points, TPA1 and TPA2, connected via XC blocks. A 'Protected Subnetwork Connection' line connects TPA1 to TPB1. A dashed 'Protecting Subnetwork Connection' line connects TPA2 to TPB2. NE-B is more complex, featuring a CPG (Connection Protection Group) containing an MPCP U-Pd and an MPCP U-Pg. TPB1 feeds the unprotected legs (TPBW, TPBX) and the working side of the protected legs (TPBY, TPBZ) via XC blocks. TPB2 feeds the protection side of the protected legs (TPBY, TPBZ) via XC blocks. Signal flow is indicated by a large arrow pointing right. Right arrow](318886a86a1dcc59e1fc83db6f157c60_img.jpg) + +Diagram (b) illustrates a protected unidirectional subnetwork connection between NE-A and NE-B. NE-A contains a TPA, an MPXC, an XC, TPA1, and TPA2. NE-B contains an MPXC, a TPB1, a CPG (containing MPCP U-Pd and MPCP U-Pg), XC blocks, TPBW, TPBX, TPBY, TPBZ, and TPB2. Signal flow is indicated by arrows pointing from NE-A to NE-B. Protection paths are indicated by dashed lines connecting TPA2 to TPB2. + +Protected Subnetwork Connection + +Signal Flow + +Protecting Subnetwork Connection + +Diagram (b) showing a protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B. NE-A now includes an MPXC and two output termination points, TPA1 and TPA2, connected via XC blocks. A 'Protected Subnetwork Connection' line connects TPA1 to TPB1. A dashed 'Protecting Subnetwork Connection' line connects TPA2 to TPB2. NE-B is more complex, featuring a CPG (Connection Protection Group) containing an MPCP U-Pd and an MPCP U-Pg. TPB1 feeds the unprotected legs (TPBW, TPBX) and the working side of the protected legs (TPBY, TPBZ) via XC blocks. TPB2 feeds the protection side of the protected legs (TPBY, TPBZ) via XC blocks. Signal flow is indicated by a large arrow pointing right. Right arrow + +**b) Protected unidirectional subnetwork connection between NE-A and NE-B with broadcast in NE-B** + +T1517100-94 + +### Figure B.7/G.774.4 – Unidirectional upstream point-to-multipoint cross-connection and connection protection (Only the legs TPBY and TPBZ are protected) + +### B.3 Bidirectional subnetwork connection protection in rings + +See Figure B.8. + +![Diagram (A), (B), and (C) showing ADM ring configurations. (A) Without protection: single line ring. (B) With protection: dual line ring. (C) With protection: dual line ring with a failure (X) on the top right segment. Nodes are labeled A, B, C, D with ADM boxes. Arrows show clockwise traffic. External connections are at nodes A and C.](cfb98c691c1af5befe32ff9442eea511_img.jpg) + +(A) Without protection + +(B) With protection + +(C) With protection T1517110-94 + +Diagram (A), (B), and (C) showing ADM ring configurations. (A) Without protection: single line ring. (B) With protection: dual line ring. (C) With protection: dual line ring with a failure (X) on the top right segment. Nodes are labeled A, B, C, D with ADM boxes. Arrows show clockwise traffic. External connections are at nodes A and C. + +a) Uniform Route + +![Diagram (A), (B), and (C) showing NE ring configurations. (A) Without protection: single line ring. (B) With protection: dual line ring. (C) With protection: dual line ring with a failure (X) on the top right segment. Nodes are labeled A, B, C, D with NE boxes. Arrows show clockwise traffic. External connections are at nodes A and C.](b51423b6c049f5b5fcde42e50b58f18b_img.jpg) + +(A) Without protection + +(B) With protection + +(C) With protection T1517120-94 + +Diagram (A), (B), and (C) showing NE ring configurations. (A) Without protection: single line ring. (B) With protection: dual line ring. (C) With protection: dual line ring with a failure (X) on the top right segment. Nodes are labeled A, B, C, D with NE boxes. Arrows show clockwise traffic. External connections are at nodes A and C. + +b) Diverse route: counter clockwise + +![Legend for the diagrams. A solid line represents 'Working SNC'. A double line represents 'Protecting SNC'. An 'X' represents 'Failure'.](a1890b9a9b85f13e67ed59bbad623659_img.jpg) + +Working SNC + +Protecting SNC + +X Failure + +Legend for the diagrams. A solid line represents 'Working SNC'. A double line represents 'Protecting SNC'. An 'X' represents 'Failure'. + +**Figure B.8/G.774.4 – Bidirectional subnetwork connection protection** + +### B.4 Interconnection of protected rings by a cross-connect + +See Figures B.9 and B.10. + +![Figure B.9/G.774.4 – Interconnection of protected rings by a cross-connect. The diagram shows two optical rings connected via a central DXC. The top ring has nodes NE (F, E, D) and TP-A, TP-B. The bottom ring has nodes NE (G, A, B) and TP-C, TP-D. A central DXC connects TP-A to TP-C and TP-B to TP-D. A 'Zoom' circle provides a detailed view of the DXC, showing four ports (TP-A, TP-B, TP-C, TP-D) with 'U-Pg' and 'U-Pd' labels. Solid lines represent protected connections, and dashed lines represent protecting connections. A legend at the bottom left defines the line types: solid for 'Protected connection' and dashed for 'Protecting connection'. A reference code 'T1517130-94' is present.](dcc2d5a5b39f780e7a224bb01ba1ef6e_img.jpg) + +Legend for Figure B.9: + +- Protected SNC (thick solid line) +- Protecting SNC (thin solid line) + +Zoomed-in view of the DXC: + +- TP-A (U-Pg) +- TP-B (U-Pd) +- TP-C (U-Pd) +- TP-D (U-Pg) + +Legend for Zoomed view: + +- Protected connection (solid line) +- Protecting connection (dashed line) + +T1517130-94 + +Figure B.9/G.774.4 – Interconnection of protected rings by a cross-connect. The diagram shows two optical rings connected via a central DXC. The top ring has nodes NE (F, E, D) and TP-A, TP-B. The bottom ring has nodes NE (G, A, B) and TP-C, TP-D. A central DXC connects TP-A to TP-C and TP-B to TP-D. A 'Zoom' circle provides a detailed view of the DXC, showing four ports (TP-A, TP-B, TP-C, TP-D) with 'U-Pg' and 'U-Pd' labels. Solid lines represent protected connections, and dashed lines represent protecting connections. A legend at the bottom left defines the line types: solid for 'Protected connection' and dashed for 'Protecting connection'. A reference code 'T1517130-94' is present. + +Figure B.9/G.774.4 – Interconnection of protected rings by a cross-connect + +![Figure B.10/G.774.4 – Interconnection of protected rings by a cross-connect: managed objects view. This diagram shows the internal components of the cross-connects. Two CPG (Control Plane Gateway) blocks are shown, each containing an MPCP (Multi-Protocol Control Plane) and two XC (Cross-Connect) blocks. The left CPG is connected to TP-A and TP-B. The right CPG is connected to TP-C and TP-D. Arrows labeled 'DCOP', 'URP', and 'UCOP' show the flow of management and control signals between the TP nodes, MPCP, and XC blocks. Reference codes 'T1517140-94' and 'T1517130-94' are present.](9870bf462aa0d916a16d14b5a100c60a_img.jpg) + +Managed objects view of the cross-connect: + +- Left CPG: TP-A, TP-B, DCOP, URP, To, MPCP, XC, UCOP +- Right CPG: TP-C, TP-D, DCOP, URP, To, MPCP, XC, UCOP + +T1517140-94 +T1517130-94 + +Figure B.10/G.774.4 – Interconnection of protected rings by a cross-connect: managed objects view. This diagram shows the internal components of the cross-connects. Two CPG (Control Plane Gateway) blocks are shown, each containing an MPCP (Multi-Protocol Control Plane) and two XC (Cross-Connect) blocks. The left CPG is connected to TP-A and TP-B. The right CPG is connected to TP-C and TP-D. Arrows labeled 'DCOP', 'URP', and 'UCOP' show the flow of management and control signals between the TP nodes, MPCP, and XC blocks. Reference codes 'T1517140-94' and 'T1517130-94' are present. + +Figure B.10/G.774.4 – Interconnection of protected rings by a cross-connect: managed objects view + +### B.5 Interconnections of subnetwork with ADMs (SNCP/SNCP) in SNCP interworking + +See Figure B.11. + +![Diagram illustrating the interconnection of subnetworks with ADMs (SNCP/SNCP) in SNCP interworking. The top part shows a network topology with nodes A, B, C, and others, including zoomed-in views. The bottom part is a detailed view of an ADM (Add-Drop Multiplexer) structure showing internal components like sncpFabric, CPG, and TP-A, TP-B, TP-C interfaces.](1142ba0197b158bb198186fe8baccc32_img.jpg) + +The diagram illustrates the interconnection of subnetworks with ADMs (SNCP/SNCP) in SNCP interworking. The top portion shows a network topology with nodes A, B, C, and others, including zoomed-in views. The bottom portion is a detailed view of an ADM (Add-Drop Multiplexer) structure showing internal components like sncpFabric, CPG, and TP-A, TP-B, TP-C interfaces. + +The top diagram shows a network topology with nodes A, B, C, and others. Node A is connected to node B, which is connected to node C. Node C is connected to a node labeled 'Optional'. The 'Optional' node is connected to a node labeled 'Zoom'. The 'Zoom' node is connected to a node labeled 'TP-A'. The 'TP-A' node is connected to a node labeled 'TP-B'. The 'TP-B' node is connected to a node labeled 'TP-C'. The 'TP-C' node is connected to a node labeled 'NULL'. + +The bottom diagram is a detailed view of an ADM structure. It shows a box labeled 'ADM' containing several components: + + +- sncpFabric**: Contains a box labeled 'XC' with inputs 'DCOP' and 'UCOP'. +- CPG**: Contains two boxes labeled 'CPr U-Pd' and 'CPr U-Pg', both with inputs 'DCOP' and 'UCOP'. +- RRP**: A box labeled 'RRP' with an input 'NULL'. +- TP-A**: A box labeled 'TP-A' with an input 'From' and an output 'URP'. +- TP-B**: A box labeled 'TP-B' with an input 'To' and an output 'URP'. +- TP-C**: A box labeled 'TP-C' with an input 'RRP'. + + The 'URP' outputs from 'TP-A' and 'TP-B' are connected to the 'RRP' box. The 'RRP' box is also connected to the 'CPr U-Pd' and 'CPr U-Pg' boxes. The 'CPr U-Pd' and 'CPr U-Pg' boxes are connected to the 'XC' box. The 'XC' box is connected to the 'TP-A' and 'TP-B' boxes. + +Diagram illustrating the interconnection of subnetworks with ADMs (SNCP/SNCP) in SNCP interworking. The top part shows a network topology with nodes A, B, C, and others, including zoomed-in views. The bottom part is a detailed view of an ADM (Add-Drop Multiplexer) structure showing internal components like sncpFabric, CPG, and TP-A, TP-B, TP-C interfaces. + +T1517150-94 + +**Figure B.11/G.774.4 – Interconnection of subnetwork with ADMs (SNCP/SNCP) in SNCP interworking** + +### B.6 Logical connections in SNCP interworking rings + +See Figures B.12 and B.13. + +![Diagram showing logical connections in SNCP interworking rings. Four ADM (Add-Drop Multiplexer) nodes are arranged in a 2x2 grid. Each ADM contains a ring of nodes labeled A, B, and C. Arrows indicate the flow of data between nodes within an ADM and between different ADMs. External connections are shown entering and leaving the ADMs.](145d00f59802048185303f15937ea65c_img.jpg) + +The diagram illustrates the logical connections in SNCP interworking rings. It consists of four ADM (Add-Drop Multiplexer) nodes arranged in a 2x2 grid. Each ADM contains a ring of nodes labeled A, B, and C. Arrows indicate the flow of data between nodes within an ADM and between different ADMs. External connections are shown entering and leaving the ADMs. + +Top-left ADM: Node A (white circle) is connected to node B (black circle) and node C (white circle). Node B is connected to node C. Node C is connected to node A. External connections enter node A and leave node C. + +Top-right ADM: Node A (black circle) is connected to node B (white circle) and node C (black circle). Node B is connected to node C. Node C is connected to node A. External connections enter node A and leave node C. + +Bottom-left ADM: Node A (white circle) is connected to node B (black circle) and node C (white circle). Node B is connected to node C. Node C is connected to node A. External connections enter node A and leave node C. + +Bottom-right ADM: Node A (black circle) is connected to node B (white circle) and node C (black circle). Node B is connected to node C. Node C is connected to node A. External connections enter node A and leave node C. + +Inter-ADM connections: + +- Vertical: Node C of the top-left ADM is connected to node C of the bottom-left ADM. Node C of the top-right ADM is connected to node C of the bottom-right ADM. +- Horizontal: Node B of the top-left ADM is connected to node B of the top-right ADM. Node B of the bottom-left ADM is connected to node B of the bottom-right ADM. + +T1517160-94 + +Diagram showing logical connections in SNCP interworking rings. Four ADM (Add-Drop Multiplexer) nodes are arranged in a 2x2 grid. Each ADM contains a ring of nodes labeled A, B, and C. Arrows indicate the flow of data between nodes within an ADM and between different ADMs. External connections are shown entering and leaving the ADMs. + +Figure B.12/G.774.4 – Logical connections in SNCP interworking rings connectivity view + +![Figure B.13/G.774.4 – Logical connections in SNCP interworking rings: management view. The diagram shows four ADM (Add-Drop Multiplexer) nodes arranged in a square, interconnected by optical fibers. Each ADM contains a 'snepFabric' block with an 'XC' (Cross-Connect) node, a 'CPG' (Control Plane Gateway) block with 'CPr U-Pd' and 'CPr U-Pg' components, and various signaling interfaces: 'DCOP', 'UCOP', 'URP', and 'RRP'. The interfaces are connected to 'TP' (Terminal Point) nodes labeled TP-A, TP-B, and TP-C. Arrows indicate the flow of management and control signals between the TP nodes and the internal components of the ADMs. The four ADMs are interconnected in a mesh-like fashion at the TP-A and TP-B nodes. A reference code 'T1517170-94' is located at the bottom right of the diagram area.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +Figure B.13/G.774.4 – Logical connections in SNCP interworking rings: management view. The diagram shows four ADM (Add-Drop Multiplexer) nodes arranged in a square, interconnected by optical fibers. Each ADM contains a 'snepFabric' block with an 'XC' (Cross-Connect) node, a 'CPG' (Control Plane Gateway) block with 'CPr U-Pd' and 'CPr U-Pg' components, and various signaling interfaces: 'DCOP', 'UCOP', 'URP', and 'RRP'. The interfaces are connected to 'TP' (Terminal Point) nodes labeled TP-A, TP-B, and TP-C. Arrows indicate the flow of management and control signals between the TP nodes and the internal components of the ADMs. The four ADMs are interconnected in a mesh-like fashion at the TP-A and TP-B nodes. A reference code 'T1517170-94' is located at the bottom right of the diagram area. + +Figure B.13/G.774.4 – Logical connections in SNCP interworking rings: management view + +### B.7 Logical connections in MS SHARED RINGs interworking + +See Figures B.14 and B.15. + +![Diagram showing logical connections in MS SHARED RINGs interworking. Four ADM nodes are arranged in a 2x2 grid, each containing a ring with multiple ports (A, B, C). Arrows indicate bidirectional logical connections between adjacent nodes and within each node's ring. The bottom-left node is labeled 'See Zoom-B'.](47a7beddcb8a1b7abdca746967e32bb4_img.jpg) + +The diagram illustrates four ADM (Add-Drop Multiplexer) nodes arranged in a 2x2 grid, representing a mesh network of shared rings. Each ADM node is shown as a rectangular box containing a ring with several ports. The top-left ADM has ports labeled A, B, and C. The top-right ADM has two ports. The bottom-left ADM has ports labeled A, B, and C, and is labeled 'See Zoom-B'. The bottom-right ADM has two ports. Arrows indicate bidirectional logical connections between adjacent nodes (horizontal and vertical) and within each node's ring. The text 'T1517180-94' is located in the bottom right corner of the diagram area. + +Diagram showing logical connections in MS SHARED RINGs interworking. Four ADM nodes are arranged in a 2x2 grid, each containing a ring with multiple ports (A, B, C). Arrows indicate bidirectional logical connections between adjacent nodes and within each node's ring. The bottom-left node is labeled 'See Zoom-B'. + +Figure B.14/G.774.4 – Logical connections in MS SHARED RINGs interworking: connectivity view + +![Diagram showing logical connections in MS SHARED RINGS interworking management view. It consists of four ADM nodes arranged in a 2x2 grid. The top-left ADM contains an 'snepFabric' with TP-A, TP-B, and TP-C interfaces, and internal components RRP, CPG, COP, CPr B-Pd, CPr B-Pg, and NULL. The top-right ADM contains a 'fabric' with TP-A, TP-B, and TP-C interfaces, and internal components To, COP, XC (Bid), and From. The bottom-left ADM contains TP-A, TP-B, and TP-C interfaces, and internal components RRP, CPG, COP, CPr B-Pd, CPr B-Pg, and NULL. The bottom-right ADM contains TP-A, TP-B, and TP-C interfaces, and internal components To, COP, XC (Bid), and From. Arrows indicate logical connections between these components across the ADMs.](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg) + +The diagram illustrates the logical connections in MS SHARED RINGS interworking management view, showing four ADM (Add-Drop Multiplexer) nodes arranged in a 2x2 grid, interconnected by logical links. + +**Top-Left ADM:** Contains an **snepFabric** block. It has three interfaces: **TP-A**, **TP-B**, and **TP-C**. Inside the snepFabric, there are components: **RRP**, **CPG**, **COP**, **CPr B-Pd**, **CPr B-Pg**, and **NULL**. Arrows show connections between these components and the interfaces. + +**Top-Right ADM:** Contains a **fabric** block. It has three interfaces: **TP-A**, **TP-B**, and **TP-C**. Inside the fabric, there are components: **To**, **COP**, **XC (Bid)**, and **From**. Arrows show connections between these components and the interfaces. + +**Bottom-Left ADM:** Contains an **snepFabric** block, similar to the top-left one, with interfaces **TP-A**, **TP-B**, and **TP-C**, and internal components **RRP**, **CPG**, **COP**, **CPr B-Pd**, **CPr B-Pg**, and **NULL**. + +**Bottom-Right ADM:** Contains a **fabric** block, similar to the top-right one, with interfaces **TP-A**, **TP-B**, and **TP-C**, and internal components **To**, **COP**, **XC (Bid)**, and **From**. + +**Interconnections:** + +- TP-C** of the top-left ADM is connected to **TP-C** of the bottom-left ADM. +- TP-B** of the top-left ADM is connected to **TP-A** of the top-right ADM. +- TP-B** of the bottom-left ADM is connected to **TP-A** of the bottom-right ADM. +- TP-C** of the bottom-left ADM is connected to **TP-C** of the bottom-right ADM. + +External connections are shown as curved arrows pointing outwards from the **TP-A** and **TP-B** interfaces of the top and bottom ADMs. + +T1517190-94 + +Diagram showing logical connections in MS SHARED RINGS interworking management view. It consists of four ADM nodes arranged in a 2x2 grid. The top-left ADM contains an 'snepFabric' with TP-A, TP-B, and TP-C interfaces, and internal components RRP, CPG, COP, CPr B-Pd, CPr B-Pg, and NULL. The top-right ADM contains a 'fabric' with TP-A, TP-B, and TP-C interfaces, and internal components To, COP, XC (Bid), and From. The bottom-left ADM contains TP-A, TP-B, and TP-C interfaces, and internal components RRP, CPG, COP, CPr B-Pd, CPr B-Pg, and NULL. The bottom-right ADM contains TP-A, TP-B, and TP-C interfaces, and internal components To, COP, XC (Bid), and From. Arrows indicate logical connections between these components across the ADMs. + +**Figure B.15/G.774.4 – Logical connections in MS SHARED RINGS interworking: management view** + +### B.8 Logical connections in SNCP Ring and MS SHARED RING interworking + +See Figures B.16 and B.17. + +![Diagram showing logical connections in SNCP Ring and MS SHARED RING interworking. It consists of four ADM (Add-Drop Multiplexer) nodes arranged in a 2x2 grid. The top-left node is labeled 'Zoom-B' and has ports A, B, and C. The top-right node is labeled 'ADM' and has two ports. The bottom-left node is labeled 'ADM' and 'See Zoom-A', with ports A, B, and C. The bottom-right node is labeled 'ADM' and 'See Zoom-A', with ports A, B, and C. Arrows indicate the flow of data between these nodes and external sources. A small text 'T1517200-94' is in the bottom right corner.](95e259e8cb3519025066052af263f8c0_img.jpg) + +T1517200-94 + +Diagram showing logical connections in SNCP Ring and MS SHARED RING interworking. It consists of four ADM (Add-Drop Multiplexer) nodes arranged in a 2x2 grid. The top-left node is labeled 'Zoom-B' and has ports A, B, and C. The top-right node is labeled 'ADM' and has two ports. The bottom-left node is labeled 'ADM' and 'See Zoom-A', with ports A, B, and C. The bottom-right node is labeled 'ADM' and 'See Zoom-A', with ports A, B, and C. Arrows indicate the flow of data between these nodes and external sources. A small text 'T1517200-94' is in the bottom right corner. + +**Figure B.16/G.774.4 – Logical connections in SNCP Ring and MS SHARED RING interworking: connectivity view** + +![A complex network diagram showing logical connections between four ADM (Add-Drop Multiplexer) nodes. Each ADM contains various components like snepFabric, fabric, XC (Bidirectional Cross-Connect), CPG (Control Plane Group), RRP (Resilient Ring Protocol), URP (Unidirectional Ring Protocol), and COP (Control Plane). The nodes are interconnected via TP-A, TP-B, and TP-C interfaces. The diagram illustrates the management view of logical connections in an SNCP Ring and MS SHARED RING interworking scenario. The top-left ADM contains an 'snepFabric' with CPG, COP, CPr (B-Pd), and CPr (B-Pg) components. The top-right ADM contains a 'fabric' with XC (Bid) and COP. The bottom-left and bottom-right ADMs contain 'snepFabric' with XC, CPG, CPr (U-Pd), and CPr (U-Pg) components. Arrows indicate the flow of control plane signals between these components and the interfaces.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +A complex network diagram showing logical connections between four ADM (Add-Drop Multiplexer) nodes. Each ADM contains various components like snepFabric, fabric, XC (Bidirectional Cross-Connect), CPG (Control Plane Group), RRP (Resilient Ring Protocol), URP (Unidirectional Ring Protocol), and COP (Control Plane). The nodes are interconnected via TP-A, TP-B, and TP-C interfaces. The diagram illustrates the management view of logical connections in an SNCP Ring and MS SHARED RING interworking scenario. The top-left ADM contains an 'snepFabric' with CPG, COP, CPr (B-Pd), and CPr (B-Pg) components. The top-right ADM contains a 'fabric' with XC (Bid) and COP. The bottom-left and bottom-right ADMs contain 'snepFabric' with XC, CPG, CPr (U-Pd), and CPr (U-Pg) components. Arrows indicate the flow of control plane signals between these components and the interfaces. + +T1517210-94 + +**Figure B.17/G.774.4 – Logical connections in SNCP Ring and MS SHARED RING interworking: management view** + +# ANNEX C + +## State transition diagrams + +### C.1 State diagrams + +### C.2 Allowable values of switchStatus for a protected (mp) connection protection + +| State | Protection status | Description of the state | +|---------------------------------------------------------------------|----------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| STA01 | noRequest | No request is currently active on the protected connection protection. The traffic is passed through on the protected connection protection. | +| STA02 | AutoSwitchSFPending | An automatic switch Signal Failure condition is active but could not be protected due to the unavailability of the protecting connection protection. | +| STA03 | AutoSwitchSFComplete | An automatic switch has been successfully completed to the protecting connection protection due to a Signal Failure condition on the protected connection protection. | +| STA04 | ForcedSwitchComplete | A forced switch has been completed successfully to the protecting connection protection. | +| STA05 | ForcedSwitchComplete-
AutoSwitchSFPending | A forced switch to the protecting connection protection has been completed successfully. Additionally, an automatic switch Signal Failed condition is active on the protected connection protection. | +| STA06 | LockoutComplete | The protected connection protection has been locked out. | +| The following are additional values for 1 + 1 non-revertive systems | | | +| STA07 | DoNotRevert | The protected connection protection has been switched to the protecting connection protection and the request to do so has been released. The switch to the protecting connection protection is maintained. | +| The following are additional values for 1 + 1 revertive systems | | | +| STA08 | manualSwitchToProtectingComplete | The protected connection protection has completed a manual switch to the protecting connection protection. | +| STA09 | AutoSwitchCompleteWaitToRestore | An automatic switch has been successfully completed to the protecting connection protection. The switch condition has cleared on the protected connection protection, and the wait to restore timer is started for switching back (revertive systems only). | + +### C.3 Allowable values of switchStatus for a protecting (mp) connection protection + +| State | Protection status | Description of the state | +|---------------------------------------------------------------------|---------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| STA01 | noRequest | No request is present on the protecting connection protection. | +| STA02 | AutoSwitchSFToProtectingComplete | The protected connection protection has completed an automatic switch (SF) to the protecting connection protection. | +| STA03 | ForcedSwitchToProtectingComplete | The protected connection protection has completed a Forced Switch to the protecting connection protection. | +| STA04 | ForcedSwitchToProtecting-CompleteSFPresentOn-Protecting | The protected connection protection has completed a Forced Switch to the protecting connection protection. Additionally the protecting connection protection has an SF condition present (1 + 1 unidirectional systems only). | +| STA05 | LockoutComplete | The protecting connection protection has been locked out. | +| STA06 | AutomaticSwitchSFToProtectedPending | A Signal Failure condition is active on the protecting connection protection. | +| The following are additional values for 1 + 1 non-revertive systems | | | +| STA07 | DoNotRevert | The protected connection protection has been switched to the protecting connection protection and the request to do so has been released. The switch to the protecting connection protection is maintained. | +| The following are additional values for 1 + 1 revertive systems | | | +| STA08 | manualSwitchToProtectingComplete | The protected connection protection has completed a manual switch to the protecting connection protection. | +| STA09 | AutoSwitchCompleteWaitToRestore | An automatic switch has been successfully completed to the protecting connection protection. The switch condition has cleared on the protected connection protection, and the wait to restore timer is started for switching back (Only for Revertive Systems). | + +### C.4 State diagram for a protected connection protection (non-revertive) + +#### Condition + +- c1: The request on the protected connection protection has a higher priority than the existing one on the protecting connection protection. (Refer to the protection switch decision table.) +- c2: There is an auto switch condition present on the protected connection protection. +- c3: The request has been completed. +- c4: There is an auto switch condition present on the protecting connection protection. + +#### Process + +- p1: Request switch to protecting connection protection. +- p2: Release the current switch. +- p3: Notify switch report. (The protection switch report is sent by the protection group however the condition under which such notification is sent is specified in the connection protection state diagram using such process.) + +#### States + +| | | +|-------|-----------------------------------------| +| STA01 | noRequest | +| STA02 | AutoSwitchSFPending | +| STA03 | AutoSwitchSFComplete | +| STA04 | ForcedSwitchComplete | +| STA05 | ForcedSwitchCompleteAutoSwitchSFPending | +| STA06 | LockoutComplete | +| STA07 | DoNotRevert | + +#### Event + +| | | +|--------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Req. Lock. | A lockout request has been issued on the protected connection protection. | +| Rel. Lock. | A release request of lockout has been issued on the protecting connection protection. | +| Req. Force | A Forced Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Force | A release request of Forced Switch has been issued on the protected connection protection. | +| Req. Man. | A Manual Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Man. | A Release Manual Switch request has been issued. As Manual Switch is not memorized, this will result as a failed request. | +| A-S Cond. | An automatic switch condition has occurred on the protected connection protection. | +| A-S Clr | The automatic switch condition on the protecting connection protection has disappeared. | +| P-ing Avail. | One or more requests (including Lockout request) have disappeared on the protecting connection protection, so that the protecting connection protection becomes available for use in the protection scheme (i.e. the highest priority request that could remain on the protecting connection protection has lower priority than existing ones on the protected connection protection). | +| P-ing Unav. | One or more requests (including Lockout request) have appeared on the protecting connection protection, so that the protecting connection protection becomes unavailable for use in the protection scheme (i.e. the highest priority request on the protecting connection protection has higher priority than existing ones on the protected connection protection). | +| Man. P-ing | A Manual Switch request has been issued to switch from the protecting connection protection to the protected connection protection. | +| Set Rev. | The connection protection group mode has been changed from non-revertive mode to revertive mode. | + +| State diagram for a protected connection protection in a 1 + 1 non-revertive system | | | | | | | | | +|-------------------------------------------------------------------------------------|-------------------------------|-------------------------------|---------------------------|--------------------|--------------------------------|-------------------------------|-----------------------------|--| +| Event | STA01
No Req. | STA02
A-S Pend. | STA03
A-S Comp. | STA04
F-S Comp. | STA05
F-S Comp
A-S Pend. | STA06
LockComp
(Note 1) | STA07
Do not revert | | +| Req. Lock. | p3:STA06 | p3:STA06 | p2,p3:
STA06 | p2,p3:
STA06 | p2,p3:
STA06 | STA06 | p2,p3:
STA06 | | +| Rel. Lock. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | c1&c2&c3
p1,p3:STA03 | STA07
(Note 2) | | +| | | | | | | (^c1V^c3)&
c2:p3:STA02 | | | +| | | | | | | ^c2:p3:STA01 | | | +| Req. Force | c1&c3:p1,
p3:STA04 | c1&c3:p1,
p3:STA05 | p3:STA05 | STA04 | STA05 | STA06
(Note 2) | p3:STA04 | | +| | ^c1V^c3:
STA01
(Note 2) | ^c1V^c3:
STA02
(Note 2) | | | | | | | +| Rel. Force | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | p3:STA07 | c1&c3:p3:
STA03 | STA06
(Note 2) | STA07
(Note 2) | | +| | | | | | ^c1V^c3:p2,
p3: STA02 | | | | +| Req. Man. | c1&c3:p1,
p3:STA07 | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | STA07 | | +| | ^c1V^c3:
STA01
(Note 2) | | | | | | | | +| Rel. Man. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | STA07
(Note 2) | | +| A-S Cond. | c1&c3:p1,
p3:STA03 | c1&c3:p1,
p3:STA03 | STA03 | STA05 | STA05 | STA06 | p3:STA03 | | +| | ^c1V^c3:
p3:STA02 | ^c1V^c3:
STA02 | | | | | | | +| A-S Clr | – | ^c2:p3: STA01 | ^c2 & ^c4:
p3:STA07 | – | ^c2:STA04 | STA06 | – | | +| | | | ^c2 & ^c4:p2,
p3:STA01 | | c2:STA05 | | – | | +| | | | c2:STA02 | | | | – | | +| | | c2:STA02 | c2&^c1:p2,
p3:STA02 | | | | – | | +| | | | c2&c1:
STA03 | | | | | | +| P-ing Unav. | STA01 | STA02 | p2,p3:
STA02 | p2,p3:
STA01 | p2,p3:
STA02 | STA06 | p2,p3:
STA01 | | +| P-ing Avail. | STA01 | c3:p1,p3:
STA03 | – | – | – | STA06 | – | | +| | | ^c3:STA02 | | | | | | | +| Man.
P-ing | STA01 | – | – | – | – | – | p2,p3:
STA01 | | +| Set Rev. | STA01
(Note 3) | STA02
(Note 3) | STA03
(Note 3) | STA04
(Note 3) | STA05
(Note 3) | STA06
(Note 3) | p2,p3:
STA01
(Note 3) | | + +NOTE 1 – An automatic switch condition may be pending. + +NOTE 2 – It results as a failed request. + +NOTE 3 – The state table to be considered after having changed the state is the state table of the revertive system. + +### C.5 State diagram for a protecting connection protection (non-revertive) + +#### Condition + +- c1: The request on the protected connection protection has a higher priority than the existing one on the protecting connection protection. (Refer to the protection switch decision table.) +- c2: There is an auto switch condition present on the protected connection protection. +- c3: The request has been completed. +- c4: There is an auto switch condition present on the protecting connection protection. + +#### Process + +- p1: Request switch to protecting connection protection. +- p2: Release switch. +- p3: Notify switch report. (The protection switch report is sent by the protection group; however, the condition under which such notification is sent is specified in the connection protection state diagram using such process.) + +#### Event + +| | | +|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Req. Lock. | A lockout request has been issued on the protecting connection protection. | +| Rel. Lock. | A release request of lockout has been issued on the protecting connection protection. | +| Req. Force | A Forced Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Force | A release request of Forced Switch has been issued on the protected connection protection. | +| Req. Man. | A Manual Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Man. | A Release Manual Switch request has been issued. As Manual Switch is not memorized, this will result as a failed request. | +| A-S Cond. | An automatic switch condition has occurred on the protecting connection protection. | +| A-S Clr | The automatic switch condition on the protecting connection protection has disappeared. | +| P-ted Lock | The protected connection protection has been locked out. | +| P-ted Avail. | One or more A-S requests have disappeared on the protected connection protection, so that the protected connection protection becomes available for use in the protection scheme (i.e. the highest priority request that could remain on the protected connection protection has lower priority than existing ones on the protecting connection protection). | +| P-ted Unav. | One or more A-S requests have appeared on the protected connection protection, so that the protected connection protection becomes unavailable for use in the protection scheme (i.e. the highest priority request on the protected connection protection has higher priorities than existing ones on the protected connection protection). | +| Set Rev. | The connection protection group mode has been changed from non-revertive to revertive mode. | +| Req. Man. To P-ted | A Manual Switch request has been issued to switch from the protecting connection protection to the protected connection protection. | + +#### States + +| | | +|-------|-------------------------------------------------------| +| STA01 | noRequest | +| STA02 | AutoSwitchSFTToProtectingComplete | +| STA03 | ForcedSwitchToProtectingComplete | +| STA04 | ForcedSwitchToProtectingCompleteSFPresentOnProtecting | +| STA05 | LockoutComplete | +| STA06 | AutomaticSwitchSFTToProtectedPending | +| STA07 | DoNotRevert | + +| State diagram for a protected connection protection in a 1 + 1 non-revertive system | | | | | | | | +|-------------------------------------------------------------------------------------|---------------------------------|-------------------------------------------|-------------------------------------|-----------------------------------------|-------------------------------|---------------------------------------------------------------|--------------------------| +| Event | STA01
No Req. | STA02
A-S Comp. | STA03
F-S Comp. | STA04
F-S Comp.
A-S Pend. | STA05
LockComp
(Note 1) | STA06
A-S Pend. | STA07
Do Not Revert | +| Req. Lock. | p3:STA05 | p2,p3: STA05 | p2,p3: STA05 | p2,p3: STA05 | STA05 | p3: STA05 | p2,p3: STA05 | +| Rel. Lock. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | ^c4:STA01
c4: STA06 | STA06
(Note 2) | STA07
(Note 2) | +| Req. Force | p1,p3:
STA03 | p3:STA03 | STA03 | STA04 | STA05
(Note 2) | p1,p3:
STA04 | p3:STA03 | +| Rel. Force | STA01
(Note 2) | STA02
(Note 2) | ^c2:p3:
STA07
c2:p3:
STA02 | ^c1:p3:
STA02
^c1:p2,p3:
STA06 | STA05
(Note 2) | STA06
(Note 2) | STA07
(Note 2) | +| Req. Man. | p1,p3:
STA07 | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | STA07 | +| Rel. Man. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | STA07
(Note 2) | +| A-S Cond. | STA06 | c1:STA02
^c1:p2,p3:
STA06 | STA04 | STA04 | STA05 | STA06 | p2,p3:
STA06 | +| A-S Clr | – | STA02 | – | c4:STA04
^c4:STA03 | STA05 | c1:p1,p3:
STA02
^c1^c4:p3:
STA01
^c1&c4:
STA06 | – | +| P-ted Lock | STA01 | ^c4:p2,p3:
STA01
c4:p2,p3:
STA06 | p2,p3:
STA01 | p2,p3: STA06 | STA05 | STA06 | p2,p3: STA01 | +| P-ted Unav. | c3:p1,p3:
STA02
^c3:STA01 | STA02 | STA03 | STA04 | STA05 | c1&c3:p1,
p3:STA02
^c1V^c3:
STA06 | p3:STA02 | +| P-ted Avail. | STA01 | ^c4:p3
STA07
c4:p2,p3:
STA06 | STA03 | STA04 | STA05 | STA06 | STA07 | +| Req. Man. To P-ted | STA01 | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | p2,p3:
STA01 | +| Set Rev. | STA01
(Note 3) | STA02
(Note 3) | STA03
(Note 3) | STA04
(Note 3) | STA05
(Note 3) | STA06
(Note 3) | p2,p3: STA01
(Note 3) | + +NOTE 1 – An automatic switch condition may be pending. +NOTE 2 – It results as a failed request. +NOTE 3 – The state table to be considered after having changed the state is the state table of the revertive system. + +### **C.6 State diagram for a protected connection protection (revertive)** + +#### **Condition** + +- c1: The request on the protected connection protection has a higher priority than the existing one on the protecting connection protection. (Refer to the protection switch decision table.) +- c2: There is an auto switch condition present on the protected connection protection. +- c3: The request has been completed. +- c4: There is an auto switch condition present on the protecting connection protection. + +#### **Process** + +- p1: Request switch to protecting connection protection. +- p2: Release the current switch. +- p3: Notify switch report. (The protection switch report is sent by the protection group; however, the condition under which such notification is sent is specified in the connection protection state diagram using such process.) +- p4: Start wait to restore timer. +- p5: Stop wait to restore timer. + +#### **States** + +| | | +|-------|-----------------------------------------| +| STA01 | noRequest | +| STA02 | AutoSwitchSFPending | +| STA03 | AutoSwitchSFComplete | +| STA04 | ForcedSwitchComplete | +| STA05 | ForcedSwitchCompleteAutoSwitchSFPending | +| STA06 | LockoutComplete | +| STA08 | manualSwitchToProtectingComplete | +| STA09 | AutoSwitchCompleteWaitToRestore | + +#### **Event** + +| | | +|--------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Req. Lock. | A lockout request has been issued on the protected connection protection. | +| Rel. Lock. | A release request of lockout has been issued on the protected connection protection. | +| Req. Force | A Forced Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Force | A release request of Forced Switch has been issued on the protected connection protection. | +| Req. Man. | A Manual Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Man. | A Release of Manual Switch request has been issued. | +| A-S Cond. | An automatic switch condition has occurred on the protected connection protection. | +| A-S Clr | The automatic switch condition has disappeared. | +| P-ing Avail. | One or more requests (including Lockout request) have disappeared on the protecting connection protection, so that the protecting connection protection becomes available for use in the protection scheme (i.e. the highest priority request that could remain on the protecting connection protection has lower priority than existing ones on the protected connection protection). | + +| | | +|--------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| P-ing Unav. | One or more requests (including Lockout request) have appeared on the protecting connection protection, so that the protecting connection protection becomes unavailable for use in the protection scheme (i.e. the highest priority request on the protecting connection protection has higher priority than existing ones on the protected connection protection). | +| WTR | The Wait-to-Restore Time has elapsed. | +| Set Non-Rev. | The connection protection group mode has been changed from revertive to non-revertive mode. | + +| State diagram for a protected connection protection in a 1 + 1 revertive system | | | | | | | | | | | | +|---------------------------------------------------------------------------------|-------------------------------|----------------------------|-------------------------------|--------------------|--------------------------------|-------------------------------|--------------------|--------------------------|--|--|--| +| Event | STA01
No Req. | STA02
A-S Pend. | STA03
A-S Comp. | STA04
F-S Comp. | STA05
F-S Comp
A-S Pend. | STA06
LockComp
(Note 1) | STA08
M-S Comp. | STA09
A-S Comp
WTR | | | | +| Req. Lock. | p3:STA06 | p3:STA06 | p2,p3:
STA06 | p2,p3:
STA06 | p2,p3:
STA06 | STA06 | p2,p3:
STA06 | p2,p3,p5:
STA06 | | | | +| Rel. Lock. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | c1&c2&c3
p1,p3:
STA03 | STA08
(Note 2) | STA09
(Note 2) | | | | +| | | | | | | (^c1V^c3)&
c2:p3:
STA02 | | | | | | +| | | | | | | ^c2:p3:
STA01 | | | | | | +| Req. Force | c1&c3:p1,
p3:STA04 | c1&c3:p1,
p3:STA05 | p3:STA05 | STA04 | STA05 | STA06
(Note 2) | p3:STA04 | p3,p5:
STA04 | | | | +| | ^c1V^c3:
STA01
(Note 2) | ^c1V^c3: STA02
(Note 2) | | | | | | | | | | +| Rel. Force | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | p2,p3:
STA01 | c1:p3:
STA03 | STA06
(Note 2) | STA08
(Note 2) | STA09
(Note 2) | | | | +| | | | | | ^c1:p2,p3:
STA02 | | | | | | | +| Req. Man. | c1&c3:p1,
p3:STA08 | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | STA08 | p3,p5:
STA08 | | | | +| | ^c1V^c3:
STA01
(Note 2) | | | | | | | | | | | +| Rel. Man. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | p2,p3:
STA01 | STA09
(Note 2) | | | | +| A-S Cond. | c1&c3:p1,
p3:STA03 | c1&c3:p1,
p3:STA03 | STA03 | STA05 | STA05 | STA06 | p3:STA03 | p3,p5:
STA03 | | | | +| | ^c1V^c3:
p3:STA02 | ^c1V^c3: STA02 | | | | | | | | | | +| A-S Clr | - | ^c2:p3: STA01 | ^c2 & ^c4:
p3,p4:
STA09 | - | ^c2:STA04 | STA06 | - | - | | | | +| | | | ^c2 & c4:p2,
p3:STA01 | | c2:STA05 | | | | | | | +| | | c2:STA02 | c2&^c1:p2,
p3:STA02 | | | | | | | | | +| | | | c2&c1: STA03 | | | | | | | | | + +| State diagram for a protected connection protection in a 1 + 1 revertive system | | | | | | | | | +|--------------------------------------------------------------------------------------------------------------------------|-------------------|------------------------------|-------------------|-------------------|-------------------|-------------------|--------------------------|---------------------------------| +| P-ing Unav. | STA01 | STA02 | p2,p3:
STA02 | p2,p3:
STA01 | p2,p3:
STA02 | STA06 | p2,p3:
STA01 | p2,p3,p5:
STA01 | +| P-ing Avail. | STA01 | c3:p1,p3: STA03
^c3:STA02 | – | – | – | STA06 | – | – | +| WTR | – | – | – | – | – | – | – | p2,p3:
STA01 | +| Set
Non-Rev. | STA01
(Note 3) | STA02
(Note 3) | STA03
(Note 3) | STA04
(Note 3) | STA05
(Note 3) | STA06
(Note 3) | p3:STA07
(Notes 3, 4) | p3,p5:
STA07
(Notes 3, 4) | +| NOTE 1 – An automatic switch condition may be pending. | | | | | | | | | +| NOTE 2 – It results as a failed request. | | | | | | | | | +| NOTE 3 – The state table to be considered after changing the state is the state table of the non-revertive system. | | | | | | | | | +| NOTE 4 – This state pertains to the state diagram for a protected connection protection in a 1 + 1 non-revertive system. | | | | | | | | | + +### C.7 State diagram for a protecting connection protection (revertive) + +#### Condition + +- c1: The request on the protected connection protection has a higher priority than the existing one on the protecting connection protection. (Refer to the protection switch decision table.) +- c2: There is an auto switch condition present on the protected connection protection. +- c3: The request has been completed. +- c4: There is an auto switch condition present on the protecting connection protection. + +#### Process + +- p1: Request switch to protecting connection protection. +- p2: Release switch. +- p3: Notify switch report. (The protection switch report is sent by the protection group; however, the condition under which such notification is sent is specified in the connection protection state diagram using such process.) +- p4: Start wait to restore timer. +- p5: Stop wait to restore timer. + +#### Event + +| | | +|--------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Req. Lock. | A lockout request has been issued on the protecting connection protection. | +| Rel. Lock. | A release request of lockout has been issued on the protecting connection protection. | +| Req. Force | A Forced Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Force | A release request of Forced Switch has been issued on the protected connection protection. | +| Req. Man. | A Manual Switch request has been issued to switch from the protected connection protection to the protecting connection protection. | +| Rel. Man. | A Release of Manual Switch request has been issued. | +| A-S Cond. | An automatic switch condition has occurred on the protecting connection protection. | +| A-S Clr | The automatic switch condition on the protecting connection protection has disappeared. | +| P-ted Lock | The protected connection protection has been locked out. | +| P-ted Avail. | One or more A-S requests have disappeared on the protected connection protection, so that the protected connection protection becomes available for use in the protection scheme (i.e. the highest priority request that could remain on the protected connection protection has lower priority than existing ones on the protecting connection protection). | +| P-ted Unav. | One or more A-S requests have appeared on the protected connection protection, so that the protected connection protection becomes unavailable for use in the protection scheme (i.e. the highest priority request on the protected connection protection has higher priorities than existing ones on the protecting connection protection). | +| WTR | The Wait-to-Restore Time has elapsed. | +| Set Non-Rev. | The connection protection group mode has been changed from revertive to non-revertive mode. | + +#### States + +| | | +|-------|-------------------------------------------------------| +| STA01 | noRequest | +| STA02 | AutoSwitchSFTToProtectingComplete | +| STA03 | ForcedSwitchToProtectingComplete | +| STA04 | ForcedSwitchToProtectingCompleteSFPresentOnProtecting | +| STA05 | LockoutComplete | +| STA06 | AutomaticSwitchSFPending | +| STA08 | manualSwitchToProtectingComplete | +| STA09 | AutoSwitchCompleteWaitToRestore | + +| State diagram for a protecting connection protection in a 1 + 1 revertive system | | | | | | | | | +|----------------------------------------------------------------------------------|-----------------------------------------|--------------------------------------------------|--------------------|---------------------------------|---------------------------------------|------------------------------------------------------------------------|--------------------------|---------------------------------| +| Event | STA01
No Req. | STA02
A-S
Comp. | STA03
F-S Comp. | STA04
F-S Comp.
A-S Pend. | STA05
F-S Comp
Comp
(Note 1) | STA06
A-S Pend. | STA08
M-S Comp. | STA09
A-S Comp
WTR | +| Req. Lock. | p3:STA05 | p2,p3:
STA05 | p2,p3:
STA05 | p2,p3:
STA05 | STA05 | p3:
STA05 | p2,p3:
STA06 | p2,p3,p5:
STA06 | +| Rel. Lock | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | ^c4:STA01
c4: STA06 | STA06
(Note 2) | STA08
(Note 2) | STA09
(Note 2) | +| Req. Force | p1,p3:
STA03 | p3:STA03 | STA03 | STA04 | STA05
(Note 2) | p1,p3:
STA04 | p3:
STA03 | p3,p5:
STA03 | +| Rel. Force | STA01
(Note 2) | STA02
(Note 2) | p2,p3:
STA01 | p2,p3:
STA06 | STA05
(Note 2) | STA06
(Note 2) | STA08
(Note 2) | STA09
(Note 2) | +| Req. Man. | p1,p3:
STA08 | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | STA08 | p3,p5:
STA08 | +| Rel. Man. | STA01
(Note 2) | STA02
(Note 2) | STA03
(Note 2) | STA04
(Note 2) | STA05
(Note 2) | STA06
(Note 2) | p2,p3:
STA01 | STA09
(Note 2) | +| A-S Cond. | STA06 | c1:STA02

^c1:p2,p3:
STA06 | STA04 | STA04 | STA05 | STA06 | p2,p3:
STA06 | p2,p3,p5:
STA06 | +| A-S Clr | – | STA02 | – | c4:STA04

^c4:STA03 | STA05 | c1:p1,p3:
STA02

^c1&^c4:
p3:STA01

^c1&c4:
STA06 | – | – | +| P-ted Lock | STA01 | ^c4: p2,p3:
STA01

c4:p2,p3:
STA06 | p2,p3:
STA01 | p2,p3:
STA06 | STA05 | STA06 | p2,p3:
STA01 | p2,p3,p5:
STA01 | +| P-ted Unav. | c3:p1,p3:
STA02

^c3:
STA01 | STA02 | STA03 | STA04 | STA05 | c1&c3:p1,
p3:STA02

^c1V^c3:
STA06 | p3: STA02 | p3,p5:
STA02 | +| P-ted Avail. | STA01 | ^c4:p2,p3:
STA06

c4:p2,p3,
p4:STA09 | STA03 | STA04 | STA05 | STA06 | STA08 | – | +| WTR | – | – | – | – | – | – | – | p2,p3:
STA01 | +| Set Non-Rev. | STA01
(Note 3) | STA02
(Note 3) | STA03
(Note 3) | STA04
(Note 3) | STA05
(Note 3) | STA06
(Note 3) | p3:STA07
(Notes 3, 4) | p3,p5:
STA07
(Notes 3, 4) | + +NOTE 1 – An automatic switch condition may be pending. + +NOTE 2 – It results as a failed request. + +NOTE 3 – The state table to be considered after having changed the state is the state table of the revertive system. + +NOTE 4 – This state pertains to the state diagram for a protected connection protection in a 1 + 1 non-revertive system. + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.8012-202202-I_PDF-E/08441fa90c5fd11994626f662ac13f19_img.jpg b/marked/G/T-REC-G.8012-202202-I_PDF-E/08441fa90c5fd11994626f662ac13f19_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..28889943d62e20ec24075bafe3bd955651633bc7 --- /dev/null +++ b/marked/G/T-REC-G.8012-202202-I_PDF-E/08441fa90c5fd11994626f662ac13f19_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:7e5a3117afad6b5748037b6b1873e4e74ebe9c0df5e983a9acfaf265aa6028d9 +size 44003 diff --git a/marked/G/T-REC-G.8012-202202-I_PDF-E/10781f43062bf3e9601a1e086710556c_img.jpg b/marked/G/T-REC-G.8012-202202-I_PDF-E/10781f43062bf3e9601a1e086710556c_img.jpg 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+DIGITAL SYSTEMS AND NETWORKS + +Packet over Transport aspects – MPLS over Transport +aspects + +--- + +**Dual-homing protection for multi-protocol label +switching transport profile pseudowires** + +Recommendation ITU-T G.8133 + +ITU-T + +![ITU International Telecommunication Union logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a stylized globe with a red lightning bolt striking through it. The letters "ITU" are prominently displayed in blue, with the full name "International Telecommunication Union" written in smaller blue text to the right. + +ITU International Telecommunication Union logo + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| Ethernet over Transport aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Synchronization, quality and availability targets | G.8200–G.8299 | +| Service Management | G.8600–G.8699 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.8133 + +# Dual-homing protection for multi-protocol label switching transport profile pseudowires + +## Summary + +Recommendation ITU-T G.8133 provides architecture and mechanisms for pseudowire (PW) dual-homing protection in multi-protocol label switching transport profile (MPLS-TP) networks. It also describes the dual-homing coordination (DHC) protocol described in [IETF RFC 8184] and [IETF RFC 8185]. + +The mechanisms defined herein protect point-to-point MPLS-TP PWs against failures within or at the edges of the MPLS-TP network. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.8133 | 2019-08-29 | 15 | 11.1002/1000/14009 | + +## Keywords + +Dual-homing, MPLS-TP, protection. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Overview..... | 3 | +| 7 Dual-homing protection architecture ..... | 4 | +| 7.1 One-side dual-homing ..... | 5 | +| 7.2 Two-side dual-homing..... | 5 | +| 8 Protection signalling ..... | 5 | +| 9 Functional model ..... | 5 | +| 10 Hold-off timer ..... | 8 | +| 11 Wait-to-restore timer ..... | 8 | +| 12 Protection procedures ..... | 8 | +| 13 External commands ..... | 9 | +| 14 Failure detection ..... | 9 | +| Annex A – Forwarding state tables of protection switching..... | 10 | +| Appendix I – One-side and two-side dual-homing protection examples..... | 11 | +| I.1 One-side dual-homing ..... | 11 | +| I.2 Two-side dual-homing..... | 11 | +| Appendix II – Network objectives ..... | 13 | + + + +## Recommendation ITU-T G.8133 + +## Dual-homing protection for multi-protocol label switching transport profile pseudowires + +# 1 Scope + +This Recommendation provides architecture and mechanisms for pseudowire (PW) dual-homing protection in multi-protocol label switching transport profile (MPLS-TP) networks. It also describes the dual-homing coordination (DHC) protocol defined in [IETF RFC 8184] and [IETF RFC 8185]. + +Both one-side and two-side dual-homing protection mechanisms are provided. + +The mechanisms defined herein protect point-to-point MPLS-TP PWs against failures within or at the edges of the MPLS-TP network. + +This Recommendation provides a representation of the MPLS-TP technology using the methodologies that have been used for other transport technologies (e.g., synchronous digital hierarchy (SDH), optical transport network (OTN) and the Ethernet).1 + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.808] Recommendation ITU-T G.808 (2016), *Terms and definitions for network protection and restoration*. +- [ITU-T G.7701] Recommendation ITU-T G.7701 (2016), *Common control aspects*. +- [ITU-T G.8113.1] Recommendation ITU-T G.8113.1/Y.1372.1 (2016), *Operations, administration and maintenance mechanisms for MPLS-TP in packet transport networks*. +- [ITU-T G.8121] Recommendation ITU-T G.8121 (2018), *Characteristics of MPLS-TP equipment functional blocks*. +- [ITU-T G.8131] Recommendation ITU-T G.8131 (2014), *Linear protection switching for MPLS transport profile*. +- [ITU-T X.84] Recommendation ITU-T X.84 (2004), *Support of frame relay services over MPLS core networks* +- [IETF RFC 3985] IETF RFC 3985 (2005), *Pseudo wire emulation edge-to-edge (PWE3) architecture*. +- [IETF RFC 5586] IETF RFC 5586 (2009), *MPLS generic associated channel*. +- [IETF RFC 5654] IETF RFC 5654 (2009), *Requirements of an MPLS transport profile*. +- [IETF RFC 6371] IETF RFC 6371 (2011), *Operations, administration, and maintenance framework for MPLS-based transport networks*. + +--- + +1 This ITU-T Recommendation is intended to be aligned with the IETF MPLS RFCs normatively referenced by this Recommendation. + +[IETF RFC 8184] IETF RFC 8184 (2017), *Dual-homing protection for MPLS and the MPLS transport profile (MPLS-TP) pseudowires*. + +[IETF RFC 8185] IETF RFC 8185 (2017), *Dual-homing coordination for MPLS transport profile (MPLS-TP) pseudowires protection*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +**3.1.1 attachment circuit (AC)** [IETF RFC 3985]. + +**3.1.2 customer edge (CE)** [ITU-T X.84]. + +**3.1.3 protection transport entity** [ITU-T G.808]. + +**3.1.4 provider edge (PE)** [ITU-T X.84]. + +**3.1.5 recovery domain** [ITU-T G.7701]. + +**3.1.6 working transport entity** [ITU-T G.808]. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 attachment circuit recovery domain:** A recovery domain that is adjacent to the multi-protocol label switching transport profile (MPLS-TP) dual-homing protection domain and provides reliable transfer of information of the client traffic using two redundant attachment circuits between the MPLS-TP dual-homing protection domain and one customer edge node. + +**3.2.2 dual-homing nodes:** Two provider edge (PE) nodes that are dual homed to the same customer edge node to provide PE node resiliency at the boundary of the multi-protocol label switching transport profile transport network. + +**3.2.3 dual-node interconnection transport entity:** The transport entity (i.e., pseudowire) established between dual-homing nodes. The dual-node interconnection transport entity is pre-established and used when there is a need for fast switchover. + +**3.2.4 multi-protocol label switching transport profile dual-homing protection domain:** A recovery domain that uses the mechanisms described in this Recommendation to provide reliable transfer of information of client traffic through a multi-protocol label switching transport profile network. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|-----------------------------------| +| AC | Attachment Circuit | +| APC | Automatic Protection Coordination | +| CE | Customer Edge | +| DHC | Dual-Homing Coordination | +| DNI | Dual-Node Interconnection | +| G-ACH | Generic Associated Channel | +| LSP | Label Switched Path | + +| | | +|---------|--------------------------------------------------| +| MEP | Maintenance Entity Point | +| MPLS | Multi-Protocol Label Switching | +| MPLS-TP | Multi-Protocol Label Switching Transport Profile | +| OAM | Operation, Administration and Maintenance | +| PE | Provider Edge | +| PW | Pseudowire | +| SD | Signal Degrade | +| SF | Signal Fail | +| WTR | Wait to Restore | + +# 5 Conventions + +In this document, the term DHC protocol is used to describe the means to coordinate the two MPLS-TP dual-homing nodes via the exchange of messages as described in [IETF RFC 8185]. + +# 6 Overview + +[IETF RFC 8184] describes the scenarios and applications for using dual-node interconnection (DNI) PWs to provide dual-homing protection. Both one-side and two-side dual-homing protection scenarios are provided as described in clauses 2.2.1 and 2.2.2 of [IETF RFC 8184], respectively. + +Figure 6-1 illustrates a reference network to describe the one-side dual-homing protection scenario where one customer edge (CE) (i.e., CE1) is attached to single node A and another CE (i.e., CE2) is attached to two dual-homing nodes (Z1 and Z2). A working transport entity (i.e., working PW) connects node A to node Z1, a protection transport entity (i.e., protection PW) connects node A to node Z2, and a DNI transport entity (DNI PW) is used to provide connectivity between nodes Z1 and Z2 during protection-switching conditions. MPLS-TP label switched paths (LSPs) are established as underlay server-layer trails for each PW, but they are not shown in Figure 6-1. + +In Figure 6-1, if an attachment circuit (AC) to Z1 (i.e., AC1) fails, then the AC to Z2 (i.e., AC2) is activated and DNI PW forwards the traffic between Z1 and Z2, so that the working PW works as usual. + +![Figure 6-1: One-side MPLS-TP dual-homing reference network diagram. The diagram shows a network topology where Node A is connected to CE1 via AC3. Node A is also connected to Node Z1 via a Working PW and to Node Z2 via a Protection PW. Node Z1 and Node Z2 are connected to each other via a DNI PW. Node Z1 is connected to CE2 via AC1, and Node Z2 is connected to CE2 via AC2. The diagram is divided into two domains by vertical dashed lines: the 'MPLS-TP dual-homing protection domain' (containing Node A, Node Z1, and Node Z2) and the 'AC recovery domain' (containing CE1 and CE2). The label 'G.8133(19)_F6-1' is present at the bottom right.](0b87abe67b21a93777287649c33e755d_img.jpg) + +Figure 6-1: One-side MPLS-TP dual-homing reference network diagram. The diagram shows a network topology where Node A is connected to CE1 via AC3. Node A is also connected to Node Z1 via a Working PW and to Node Z2 via a Protection PW. Node Z1 and Node Z2 are connected to each other via a DNI PW. Node Z1 is connected to CE2 via AC1, and Node Z2 is connected to CE2 via AC2. The diagram is divided into two domains by vertical dashed lines: the 'MPLS-TP dual-homing protection domain' (containing Node A, Node Z1, and Node Z2) and the 'AC recovery domain' (containing CE1 and CE2). The label 'G.8133(19)\_F6-1' is present at the bottom right. + +**Figure 6-1 – One-side MPLS-TP dual-homing reference network** + +[IETF RFC 8185] specifies mechanisms to provide dual-homing protection against failures within the MPLS-TP dual-homing protection domain and the DHC protocol to coordinate protection- + +switching action between dual-homing nodes (Z1 and Z2). The coordination messages are transported on the DNI transport entity (DNI PW) over the generic associated channel (G-ACh). + +This Recommendation assumes that the automatic protection coordination (APC) protocol, described in [ITU-T G.8131], is used to coordinate protection-switching actions between the two ends of the MPLS-TP dual-homing protection domains (i.e., nodes A and Z2). + +Figure 6-2 illustrates a reference network to describe the two-side dual-homing protection scenario where CE1 is also attached to two dual-homing nodes (A1 and A2). In this case, one DHC protocol is used to coordinate protection switching between nodes A1 and A2, the other DHC protocol is used to coordinate protection switching between nodes Z1 and Z2, and the APC protocol is assumed to be used to coordinate protection switching between nodes A2 and Z2. + +![Figure 6-2: Two-side MPLS-TP dual-homing reference network diagram. The diagram shows two Customer Equipment (CE) units, CE1 and CE2, connected to four dual-homing nodes: Node A1, Node A2, Node Z1, and Node Z2. CE1 is connected to Node A1 via AC1 and to Node A2 via AC2. CE2 is connected to Node Z1 via AC3 and to Node Z2 via AC4. Node A1 and Node Z1 are connected by a 'Working PW'. Node A2 and Node Z2 are connected by a 'Protection PW'. Node A1 and Node A2 are connected by 'DNI PW1'. Node Z1 and Node Z2 are connected by 'DNI PW2'. The network is divided into three domains by vertical dashed lines: an 'AC recovery domain' on the left (containing CE1 and nodes A1, A2), an 'MPLS-TP dual-homing protection domain' in the center (containing nodes A1, A2, Z1, Z2), and another 'AC recovery domain' on the right (containing CE2 and nodes Z1, Z2). A horizontal double-headed arrow at the bottom indicates these domains. The diagram is labeled 'G.8133(19)_F6-2' in the bottom right corner.](e6df2733626a85205c1db682e6259c46_img.jpg) + +Figure 6-2: Two-side MPLS-TP dual-homing reference network diagram. The diagram shows two Customer Equipment (CE) units, CE1 and CE2, connected to four dual-homing nodes: Node A1, Node A2, Node Z1, and Node Z2. CE1 is connected to Node A1 via AC1 and to Node A2 via AC2. CE2 is connected to Node Z1 via AC3 and to Node Z2 via AC4. Node A1 and Node Z1 are connected by a 'Working PW'. Node A2 and Node Z2 are connected by a 'Protection PW'. Node A1 and Node A2 are connected by 'DNI PW1'. Node Z1 and Node Z2 are connected by 'DNI PW2'. The network is divided into three domains by vertical dashed lines: an 'AC recovery domain' on the left (containing CE1 and nodes A1, A2), an 'MPLS-TP dual-homing protection domain' in the center (containing nodes A1, A2, Z1, Z2), and another 'AC recovery domain' on the right (containing CE2 and nodes Z1, Z2). A horizontal double-headed arrow at the bottom indicates these domains. The diagram is labeled 'G.8133(19)\_F6-2' in the bottom right corner. + +**Figure 6-2 – Two-side MPLS-TP dual-homing reference network** + +The mechanisms used to provide protection against failures within the AC recovery domains lie outside the scope of this Recommendation. It is assumed that these mechanisms will activate one and only one AC at a given time within each AC recovery domain and are capable of reporting the active/stand-by status of a local AC to the PE node. + +MPLS-TP PW dual-homing protection mechanisms operates independently from the client layer protocols (i.e., the client services in transport) encapsulated in the PW and therefore are applicable to any PW client such as the Ethernet, time division multiplexing and asynchronous transfer mode. + +Through these working and protection PWs and their LSPs, services over dual-homing nodes can be protected from a single failure on either the working PW, the protection PW, a dual-homing node (node Z1 or node Z2) or an AC connecting a CE with dual-homing nodes. Recovery of multiple-failure scenarios lies outside the scope of this Recommendation. + +# 7 Dual-homing protection architecture + +Dual-homing protection architecture is based on 1:1 PW trail protection. + +It supports only the bidirectional protection-switching type, i.e., both directions of the connection for a service, including the affected direction and the unaffected direction, are switched to protection. + +Both revertive and non-revertive operation types are supported. + +Both one-side and two-side dual-homing architectures are supported. + +## **7.1 One-side dual-homing** + +In one-side dual-homing, only one side of the client sites is dual homed. The scenario is described in clause 2.2.1 of [IETF RFC 8184]. + +## **7.2 Two-side dual-homing** + +In two-side dual-homing, both sides of the client sites are dual homed. The scenario is described in clause 2.2.2 of [IETF RFC 8184]. + +# **8 Protection signalling** + +To coordinate the switching of working and protection PWs (i.e., the working and protection transport entities) and activate the DNI PW (i.e., DNI transport entity), between the dual-homing nodes, the DHC protocol as specified in clause 4 of [IETF RFC 8185] shall be used. Any status and switchover coordination messages between the dual-homing nodes shall be sent over the G-ACh [IETF RFC 5586] of the DNI PW. + +The switching of working and protection PWs, between the two ends of the MPLS-TP dual-homing protection domains, is coordinated using the mechanisms described in [ITU-T G.8131]. The APC messages shall be sent over the protection PW as described in [ITU-T G.8131]. + +# **9 Functional model** + +The end points of each working transport entity shall have PW operation, administration and maintenance (OAM) functions to monitor the status of the working transport entity (working PW). Because the protection transport entity and the DNI transport entity are pre-established, the status of the protection transport entity (protection PW) and of the DNI transport entity (DNI PW) shall also be monitored at the end points using PW OAM functions. + +APC messages are transported over the protection transport entity, and the DHC messages are exchanged over the DNI transport entity. + +The functional architecture of DNI protection is shown in Figure 9-1. + +![Figure 9-1 – MPLS-TP Dual-homing protection architecture diagram. The diagram shows three nodes: Node A, Node Z1, and Node Z2. Node A is on the left, containing a bridge/selector, two MEPs (one for Working PW, one for Protection PW), and an APC process. Node Z1 is in the middle, containing two MEPs (one for Working PW, one for Protection PW), a DNI slave process, and bridges/selectors. Node Z2 is on the right, containing two MEPs (one for Working PW, one for Protection PW), a DNI Master process, an APC process, and bridges/selectors. The diagram illustrates the flow of traffic and control messages (DHC, APC) between the nodes. The Working PW and Protection PW are shown as solid lines, while the DNI PW is shown as a dashed line. The AC recovery domain is indicated on the far right.](d4af765160d04ecef538e5066006dc77_img.jpg) + +The diagram illustrates the MPLS-TP Dual-homing protection architecture across three nodes: Node A, Node Z1, and Node Z2. + +- Node A:** Contains a bridge/selector, two MEPs (one for Working PW, one for Protection PW), and an APC process. The bridge/selector is connected to the Working PW and Protection PW. The APC process exchanges status information (W-PW status, P-PW status, APC) with the MEPs and the bridge/selector. +- Node Z1:** Contains two MEPs (one for Working PW, one for Protection PW), a DNI slave process, and bridges/selectors. The Working PW and Protection PW are connected to the MEPs. The DNI slave process exchanges status information (DNI PW status, W-PW status, Local (Z1) AC status) with the MEPs and the bridges/selectors. +- Node Z2:** Contains two MEPs (one for Working PW, one for Protection PW), a DNI Master process, an APC process, and bridges/selectors. The Working PW and Protection PW are connected to the MEPs. The DNI Master process exchanges status information (DNI PW status, Local (Z2) AC status, b/s position) with the MEPs and the bridges/selectors. The APC process exchanges status information (P-PW status, W-PW status, APC info.) with the MEPs and the DNI Master process. + +Key components and connections: + +- Working PW:** Solid line connecting Node A to Node Z1. +- Protection PW:** Solid line connecting Node A to Node Z2. +- DNI PW:** Dashed line connecting Node Z1 and Node Z2, labeled with (DHC message). +- Control Messages:** + - DHC message:** Exchanged between Node Z1 and Node Z2. + - APC message:** Exchanged between Node A and Node Z2. + +The diagram is labeled G.8133(19)\_F9-1. + +Figure 9-1 – MPLS-TP Dual-homing protection architecture diagram. The diagram shows three nodes: Node A, Node Z1, and Node Z2. Node A is on the left, containing a bridge/selector, two MEPs (one for Working PW, one for Protection PW), and an APC process. Node Z1 is in the middle, containing two MEPs (one for Working PW, one for Protection PW), a DNI slave process, and bridges/selectors. Node Z2 is on the right, containing two MEPs (one for Working PW, one for Protection PW), a DNI Master process, an APC process, and bridges/selectors. The diagram illustrates the flow of traffic and control messages (DHC, APC) between the nodes. The Working PW and Protection PW are shown as solid lines, while the DNI PW is shown as a dashed line. The AC recovery domain is indicated on the far right. + +**Figure 9-1 – MPLS-TP Dual-homing protection architecture** + +Node A implements PW trail protection, as described in [ITU-T G.8121], so that protection switching to the protection PW in both directions can be realized as specified in [ITU-T G.8131]; while nodes Z1 and Z2 implement PW DNI protection, as described in this Recommendation and in [IETF RFC 8184] and [IETF RFC 8185]. + +The bridges/selectors, in nodes Z1 and Z2, implement the forwarding behaviour described in Table 1 of [IETF RFC 8185]. + +The APC process in node Z2 determines the new switching states of the working PW and the protection PW based on the local status of the protection PW (determined by the protection PW maintenance entity point (MEP)), the status of the working PW (from the DHC messages received by the DNI master process), the commands of the local operator and the APC messages exchanged with the remote node A. The switching state of a PW indicates whether the PW is active (i.e., used for transmitting and receiving traffic) or not. Only one of the working and protection PWs should be active at any given time. + +The DNI master process in node Z2 controls the bridges/selectors forwarding behaviour within node Z2, implementing the state machine described in [IETF RFC 8185] based on the local status of the DNI PW (determined by the DNI PW MEP), the local AC status, and the switching state of the protection PW (determined by the APC process). It also exchanges DHC messages with the peer DNI slave process to send the switching state of the working PW (determined by the APC process) and to receive the peer status of the working PW. + +The DNI slave process in node Z1 controls the bridges/selectors forwarding behaviour within node Z1, implementing the state machine described in [IETF RFC 8185] based on local status of the DNI PW (determined by the DNI PW MEP), the local AC status, and the switching state of the working PW (based on received DHC messages). It also transmits to the peer DNI master process, DHC messages carrying the local status of the working PW (determined by the working PW MEP). + +The MPLS-TP dual-homing protection switching is modelled as an MPLS-TP dual-homing protection sub-layer (MTd), as shown in Figures 9-2 and 9-3: + +- The MTd\_C atomic function is a connection function implementing the dual-homing protection switching using the bridges/selectors, the DNI processes and the APC process as shown in Figure 9-1. The MTd\_C atomic functions in nodes Z1 and Z2 differ depending on whether the APC process exists or not and whether the DNI process is a master or a slave. +- The MT/MTd\_A atomic function inserts/extracts the APC and DHC messages to/from the protection PW and DNI PW, respectively. + +![Diagram of MPLS-TP dual-homing protection sub-layer (Z1) showing the flow of traffic and control messages between a Working PW MEP, a Client CP, and a DNI PW MEP through various MT and MTd components.](ff0952ef692c9d960ce5f6708bcc9711_img.jpg) + +The diagram illustrates the internal architecture of the MPLS-TP dual-homing protection sub-layer in node Z1. It is enclosed in a dashed box. On the left, an 'MT\_CP' connects to a 'Working PW MEP' (represented by a triangle with three lines). This connects to an 'MT\_AP' (two circles), which then connects to an 'MT/MTd' block (a yellow trapezoid). This block connects to an 'MTd\_CP' (two circles), which connects to the 'MTd\_C' function (a yellow circle). From 'MTd\_C', another 'MTd\_CP' connects to a second 'MT/MTd' block (yellow trapezoid), which is labeled 'MT/Client'. This block connects to a 'Client\_CP' on the right. Below the 'MTd\_C' function, a vertical path consists of an 'MTd\_CP', an 'MT/MTd' block (yellow trapezoid), an 'MT\_AP', and a 'DNI PW MEP' (triangle with three lines), ending at an 'MT\_CP' at the bottom. The label 'G.8133(19)\_F9-1' is in the bottom right corner. + +Diagram of MPLS-TP dual-homing protection sub-layer (Z1) showing the flow of traffic and control messages between a Working PW MEP, a Client CP, and a DNI PW MEP through various MT and MTd components. + +Figure 9-2 – MPLS-TP dual-homing protection sub-layer (Z1) + +![Diagram of MPLS-TP dual-homing protection sub-layer (Z2).](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +The diagram illustrates the MPLS-TP dual-homing protection sub-layer (Z2). It features a central yellow oval labeled 'MTd\_C' connected to two yellow trapezoidal blocks labeled 'MT/MTd'. The left 'MT/MTd' block is connected to a 'Working PW MEP' (represented by a triangle with three vertical lines) and an 'MT\_AP' (represented by two small circles). The right 'MT/MTd' block is connected to a 'Client\_CP' (represented by two small circles) and an 'MT/Client' block (represented by a triangle with three vertical lines). Above the central 'MTd\_C' block, another 'MTd\_CP' (two small circles) is connected to a yellow trapezoidal block labeled 'MT/MTd', which is in turn connected to an 'MT\_AP' (two small circles). This 'MT\_AP' is connected to a 'DNI PW MEP' (represented by a triangle with three horizontal lines), which is finally connected to an 'MT\_CP' (two small circles) at the top. The entire structure is enclosed in a dashed rectangular box. The label 'G.8133(19)\_F9-2' is located at the bottom right of the diagram. + +Diagram of MPLS-TP dual-homing protection sub-layer (Z2). + +**Figure 9-3 – MPLS-TP dual-homing protection sub-layer (Z2)** + +## 10 Hold-off timer + +MPLS-TP dual-homing protection relies upon the hold-off timer logic described in [ITU-T G.8131] to coordinate timing of protection switches at multiple layers for working and protection PWs. + +As a consequence, the hold-off timer of the APC process within the protection PE shall be configured via MTd\_C\_MI\_PS\_HoTime. + +## 11 Wait-to-restore timer + +MPLS-TP dual-homing protection relies upon the wait to restore (WTR) state described in [ITU-T G.8131] to prevent frequent operations of the protection switch due to an intermittent defect of the working transport entity. + +As a consequence, the wait-to-restore timer of the APC process within the protection PE shall be configured via MTd\_C\_MI\_PS\_WTR. + +## 12 Protection procedures + +Protection procedures for MPLS-TP PW dual-homing mechanisms are described in clause 4.2 of [IETF RFC 8185]. + +Some examples on how they apply to one-side and two-side dual-homing scenarios are provided in Appendix I. + +## 13 External commands + +MPLS-TP dual-homing protection relies upon the external commands applied to the APC process, as described in [ITU-T G.8131], to allow operator control of the switching state of working and protection transport entities. In case of multiple protection-switching requests, the priority logic described in [ITU-T G.8131] is used to determine the switching states of the working and protection transport entities. + +As a consequence, the external command shall be input into the APC process within the protection PE via MTd\_C\_MI\_PS\_ExtCMD. + +## 14 Failure detection + +The MPLS-TP PW layer OAM is used to monitor the status of the working PW, the protection PW and the DNI PW(s). Dual-homing nodes in the dual-homing protection domain shall support the PW OAM mechanisms as defined in clause 4.3 of [IETF RFC 6371]. + +The defect conditions on each MPLS-TP PW are detected as described in [ITU-T G.8121]. + +Signal fail (SF) is declared on working and protection PW when the MPLS-TP trail termination sink (MT\_TT\_Sk) function in the MPLS-TP dual-homing protection domain detects a trail SF as described in [ITU-T G.8121]. + +Signal degrade (SD) is declared on working and protection when the MPLS-TP trail termination sink (MT\_TT\_Sk) function in the MPLS-TP dual-homing protection domain detects a trail signal degrade as described in [ITU-T G.8121]. + +DNI PW is declared to be in a down state when the MPLS-TP trail termination sink (MT\_TT\_Sk) function detects a trail SF or a remote defect indication (RDI) condition as described in [ITU-T G.8121]. + +A dual-homing node failure is regarded as the failure of the AC and of the two PWs attached to that dual-homing node. + +## **Annex A** + +### **Forwarding state tables of protection switching** + +(This annex forms an integral part of this Recommendation.) + +The state machines for MPLS-TP dual-homing protection are described in clause 4 of [IETF RFC 8185]. In order to achieve MPLS-TP dual-homing protection, the dual-homing nodes need to exchange PW status and protection coordination requests to coordinate their behaviours. + +In order to avoid potential mistakes in duplicating the state transition tables from [IETF RFC 8185], they are omitted in this Recommendation. + +## Appendix I + +### One-side and two-side dual-homing protection examples + +(This appendix does not form an integral part of this Recommendation.) + +### I.1 One-side dual-homing + +One-side dual-homing protection is shown in clause 2.2.1 of [IETF RFC 8184] and in Figure 6-1. + +When the local AC of node Z1 fails, nodes Z1 and Z2 follow the recovery procedures described in clause 4.2 of [IETF RFC 8185] while node A does not perform any protection-switching action. After the recovery procedures are completed, node A keeps forwarding the traffic between its local AC (A) and the working PW; node Z1 forwards traffic between the working PW and the DNI-PW; and node Z2 forwards traffic between the DNI-PW and its local AC (Z2). + +When the working PW fails, nodes A, Z1 and Z2 apply the recovery procedures described in clause 4.2 of [IETF RFC 8185]: in particular, nodes A and Z2 use the protection-switching mechanisms described in [ITU-T G.8131] to coordinate the activation of the protection PW. After the recovery procedures are completed, node A forwards traffic between its local AC (A) and the protection PW; node Z2 forwards traffic between the protection PW and the DNI-PW; and node Z1 forwards traffic between the DNI-PW and its local AC (Z1). + +When node Z1 fails, nodes A and Z2 follow the recovery procedures described in clause 4.2 of [IETF RFC 8185]: in particular, they use the protection-switching mechanisms described in [ITU-T G.8131] to coordinate the activation of the protection PW. After the recovery procedures are completed, node A forwards the traffic between its local AC (A) and the protection PW; and node Z2 forwards traffic between the protection PW and its local AC (Z2). + +### I.2 Two-side dual-homing + +Two-side dual-homing protection is shown in clause 2.2.2 of [IETF RFC 8184] and Figure 6-2. + +When the local AC of node Z1 fails, nodes Z1 and Z2 follow the same recovery procedures described in clause 4.2 of [IETF RFC 8185], which are independent of whether the other side is using dual-homing or not, while nodes A1 and A2 do not perform any protection-switching action. After the recovery procedures are completed, node A1 keeps forwarding traffic between its local AC (A1) and the working PW; node Z1 forwards traffic between the working PW and its DNI-PW (Z1-Z2), and node Z2 forwards traffic between its DNI-PW (Z1-Z2) and its local AC (Z2). + +When the working PW fails, nodes A1 and A2, as well as nodes Z1 and Z2, follow the same recovery procedures described in clause 4.2 of [IETF RFC 8185], which are independent of whether the other side is using dual-homing or not: in particular, nodes A2 and Z2 use the protection-switching mechanisms described in [ITU-T G.8131] to coordinate the activation of the protection PW. After the recovery procedures are completed, node A1 forwards traffic between its local AC (A1) and its DNI-PW (A1-A2); node A2 forwards the traffic between its DNI PW (A1-A2) and the protection PW; node Z2 forwards the traffic between the protection PW and its DNI-PW (Z1-Z2), and node Z1 forwards the traffic between its DNI-PW (Z1-Z2) and its local AC (Z1). + +When node Z1 fails, node Z2 follows the same recovery procedures described in clause 4.2 of [IETF RFC 8185], which are independent of whether the other side is using dual-homing or not, while nodes A1 and A2 follows the same recovery procedure described above for the case of a working PW failure: in particular, nodes A2 and Z2 use the protection-switching mechanisms described in [ITU-T G.8131] to coordinate the activation of the protection PW. After the recovery procedures are completed, node A1 forwards traffic between its local AC (A1) and its DNI-PW (A1-A2); node A2 forwards the traffic between its DNI PW (A1-A2) and the protection PW, and node Z2 forwards traffic between the protection PW and its local AC (Z2). + +## Appendix II + +## Network objectives + +(This appendix does not form an integral part of this Recommendation.) + +This appendix lists network objectives. + +- 1) MPLS-TP dual-homing protection shall be capable of protecting against the following events: + - a) MPLS-TP PW layer failures, without relying on restoration of a particular server layer; + - b) dual-homing edge node failures; + - c) ingress or egress link failures, but how the edge nodes detect an ingress or egress link failure or coordinate with the client site to switch to another dual-homing ingress or egress link lies outside the scope of this Recommendation. +- 2) Transfer time (Tt) in response to a single failure should be less than 50 ms within the MPLS-TP network. +- 3) Support only bidirectional protection switching to ensure that forward traffic and reverse traffic of a protected service are always co-routed. +- 4) Reuse the OAM mechanisms as described for MPLS-TP (e.g., see [ITU-T G.8113.1]). +- 5) Reuse the linear protection mechanism as specified in [ITU-T G.8131], and be capable to coexist with it. +- 6) The following externally initiated commands shall be supported (Requirement 76 of [IETF RFC 5654]): Lockout of working, lockout of protection (Requirement 105 of [IETF RFC 5654]), forced switch, manual switch, exercise and clear. +- 7) The following automatically initiated commands shall be supported (SF - working, SF - protection, wait-to-restore, reverse request and no request. The criteria for SF are the same as those used in [ITU-T G.8121]). +- 8) Support the nesting of multiple levels of protection (such as linear protection in the server LSP layer). To achieve this, mechanism(s) that allow for coordination of protection activities (e.g., hold-off timer) shall be supported. +- 9) Avoid protection-switching flapping (e.g., support of wait-to-restore timer). +- 10) Protection-switching activation can be initiated by either end or both ends of the MPLS-TP dual-homing protection domain. +- 11) Both revertive and non-revertive protection switching should be supported. +- 12) Prioritized protection between SF, SD and operator requests should be supported. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | 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b/marked/G/T-REC-G.8201-201104-I_PDF-E/raw.md @@ -0,0 +1,590 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.8201** + +(04/2011) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Packet over Transport aspects – Quality and availability +targets + +--- + +**Error performance parameters and objectives +for multi-operator international paths within +optical transport networks** + +Recommendation ITU-T G.8201 + +![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking across it. The letters 'ITU' are written in blue below the globe. + +International +Telecommunication +Union + +ITU logo + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| Ethernet over Transport aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Quality and availability targets | G.8200–G.8299 | +| Service Management | G.8600–G.8699 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.8201 + +## Error performance parameters and objectives for multi-operator international paths within optical transport networks + +## Summary + +Recommendation ITU-T G.8201 defines error performance parameters and objectives for international ODUk paths transported by the optical transport network (OTN), as described in Recommendation ITU-T G.709/Y.1331. While this Recommendation specifically addresses objectives for international ODUk paths, the allocation principles can be applied to the design of error performance for national or private ODUk paths. This Recommendation is based upon a block-based measurement concept using error detection code (EDC) and EDC usage inherent to the path under test; the block repetition rate being in accordance with OTN technology in accordance with Recommendation ITU-T G.709/Y.1331. This simplifies in-service measurements. The events, parameters and objectives are defined accordingly. In addition to path performance assessment, tandem connection monitoring is covered. + +## History + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.8201 | 2003-09-13 | 13 | +| 2.0 | ITU-T G.8201 | 2011-04-13 | 15 | + +## Keywords + +Background block error (BBE), block-based concept, error detection code (EDC), EDC usage, error performance objectives, error performance parameters, hypothetical reference optical path (HROP), in-service monitoring (ISM), optical channel data unit-k (ODUk) path, severely errored second (SES), tandem connection monitoring (TCM). + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2012 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|----------------------------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 1.1 Application of this Recommendation ..... | 1 | +| 1.2 Transport network layers ..... | 1 | +| 1.3 Allocation of end-to-end performance ..... | 2 | +| 2 References..... | 2 | +| 3 Terms and Definitions ..... | 3 | +| 4 Abbreviations..... | 4 | +| 5 Measurement of the block ..... | 5 | +| 5.1 In-service monitoring ..... | 5 | +| 5.2 Out-of-service measurements ..... | 5 | +| 6 Performance monitoring at the near end and far end of a path..... | 6 | +| 7 Relationship between path performance monitoring and the block-based parameters..... | 6 | +| 7.1 General ..... | 6 | +| 7.2 Estimation of the performance parameters..... | 7 | +| 7.3 Estimation of performance events at the far end of a path ..... | 7 | +| 8 Error performance objectives ..... | 7 | +| 8.1 End-to-end objectives..... | 7 | +| 8.2 Hypothetical reference optical path..... | 8 | +| 8.3 Allocation of end-to-end performance objectives ..... | 9 | +| Annex A – Criteria for entry to and exit from the unavailable state..... | 10 | +| A.1 Criteria for a single direction..... | 10 | +| A.2 Criterion for a bidirectional path ..... | 10 | +| A.3 Criterion for a unidirectional path ..... | 10 | +| A.4 Consequences on error performance measurements ..... | 11 | +| Appendix I – Flow chart illustrating the recognition of anomalies, defects, errored blocks, and SES..... | 12 | +| Appendix II – Example of OTN layer network trails ..... | 14 | +| Bibliography..... | 15 | + + + +## Recommendation ITU-T G.8201 + +## Error performance parameters and objectives for multi-operator international paths within optical transport networks + +# 1 Scope + +This Recommendation specifies error performance events, parameters and objectives for ODUk paths1 of the optical transport network (OTN), as specified in [ITU-T G.709]. Clauses 1.1 to 1.3 give further details. + +## 1.1 Application of this Recommendation + +This Recommendation is applicable to international paths of the optical transport network as described in [ITU-T G.709]. These paths are at the ODUk layer of the OTN, and are digital paths (see [ITU-T G.709] for a description of the ODUk layer). While this Recommendation specifically addresses objectives for international ODUk paths, the allocation principles can be applied to the design of error performance for national or private paths. + +The quality of client services, as well as the performance of the network elements belonging to the service layer, is outside of the scope of this Recommendation. However, ITU-T G.8201-based paths can carry various clients (e.g., SDH, ATM, GFP (i.e., IP, Ethernet, etc., encapsulated in GFP), etc.; see [ITU-T G.709]). ODUk paths meeting the objectives of this Recommendation will enable client layer traffic to meet its respective performance objectives. + +The error performance objectives are applicable to each direction of the ODUk path independently. The values apply end-to-end over a 27 500 km hypothetical reference path (see Figure 3). The performance of multiplex and cross-connect functions of client layers of the OTN (i.e., higher layers, above the OPUk, e.g., SDH, ATM, etc.; see [ITU-T G.709] for a description of the OPUk) are not included in these values. + +The parameter definitions are block-based with the block repetition rate in accordance with OTN technology, making in-service measurement convenient. In addition to in-service measurements, compliance with this Recommendation can be assessed using out-of-service measurements or estimated by measures compatible with this Recommendation as those specified in clause 7. + +The objectives given in this Recommendation are long-term objectives to be met over an evaluation period of typically 30 consecutive days (one month). Shorter measurement periods required for maintenance and bringing-into-service are covered in [b-ITU-T M.2401]. + +## 1.2 Transport network layers + +This Recommendation specifies the error performance of ODUk paths in a given transport network layer. In the context of this Recommendation, an ODUk digital path is a trail carrying an OPUk payload and associated OPUk and ODUk overhead through the layered transport network between the path terminating equipment (see Figure 1). + +--- + +1 In this Recommendation, unless otherwise specified, the term *path* means *ODUk path* ( $k = 1, 2, \text{ or } 3$ ). The nominal ODUk rates are approximately 2.5 Gbit/s for ODU1, 10 Gbit/s for ODU2, and 40 Gbit/s for ODU3. + +![Figure 1 – OTN signal structure diagram showing the hierarchy of OTN layers from Client signal down to Optical carrier network.](3121ebddccf183ca63bb9781be440a7e_img.jpg) + +The diagram illustrates the OTN signal structure hierarchy. At the top is a green box labeled 'Client signal'. Below it, a yellow box labeled 'OH' is added to the left of the signal, which is now labeled '= OCh Payload unit'. Below this, another yellow box labeled 'OH' is added to the left, and the signal is now labeled '= OCh Data unit k'. The signal is now labeled 'OPUk'. Below this, a yellow box labeled 'OH' is added to the left, and a green box labeled 'FEC' is added to the right. The signal is now labeled '= OCh Transport unit k' and 'ODUk'. Below this, the signal is labeled 'OTUk'. At the bottom, the signal is labeled 'Optical carrier network'. The diagram is labeled 'G.8201\_F01' at the bottom right. + +Figure 1 – OTN signal structure diagram showing the hierarchy of OTN layers from Client signal down to Optical carrier network. + +**Figure 1 – OTN signal structure** + +The scope of application of this Recommendation is from path-end-point to path-end-point as illustrated in Figure 2. + +![Figure 2 – Application of ITU-T G.8201 for an end-to-end ODUk path diagram showing the scope of the recommendation between two path end points A and B.](d0abac95583b52a3b35f74a215567334_img.jpg) + +The diagram shows a central oval labeled 'ODUk path layer network' connected to two rectangular boxes labeled 'A' and 'B'. Above the oval, a double-headed arrow spans from box A to box B, labeled 'Application of ITU-T G.8201'. The diagram is labeled 'G.8201(11)\_F02' at the bottom right. + +Figure 2 – Application of ITU-T G.8201 for an end-to-end ODUk path diagram showing the scope of the recommendation between two path end points A and B. + +NOTE – A and B are path end points located at the path terminations as defined in [ITU-T G.798]. + +**Figure 2 – Application of ITU-T G.8201 for an end-to-end ODUk path** + +## 1.3 Allocation of end-to-end performance + +Allocations of end-to-end performance of ODUk paths are derived using the rules laid out in clause 8.3, which are length and complexity based. Detailed allocations of ITU-T G.8201 performance to the individual components (sections, multiplexers and cross-connects, etc.) are outside the scope of this Recommendation but, when such allocations are performed, the requirements of clause 8.3 should be met. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2009), *Interfaces for the Optical Transport Network (OTN)*. +- [ITU-T G.798] Recommendation ITU-T G.798 (2010), *Characteristics of optical transport network hierarchy equipment functional blocks*. +- [ITU-T G.826] Recommendation ITU-T G.826 (2002), *End-to-end error performance parameters and objectives for international, constant bit-rate digital paths and connections*. +- [ITU-T G.827] Recommendation ITU-T G.827 (2003), *Availability performance parameters and objectives for end-to-end international constant bit-rate digital paths*. +- [ITU-T G.828] Recommendation ITU-T G.828 (2000), *Error performance parameters and objectives for international, constant bit-rate synchronous digital paths*. +- [ITU-T G.872] Recommendation ITU-T G.872 (2010), *Architecture of optical transport networks*. +- [ITU-T G.874] Recommendation ITU-T G.874 (2001), *Management aspects of optical transport network elements*. +- [ITU-T I.356] Recommendation ITU-T I.356 (2000), *B-ISDN ATM layer cell transfer performance*. + +# 3 Terms and Definitions + +This Recommendation defines the following terms: + +**3.1 error performance events:** In the following definitions, this Recommendation neither assumes nor requires that forward error correction (FEC) is used (see [ITU-T G.709]). However, if FEC is used, all the performance parameters and events are defined after FEC (i.e., post-FEC). In other words, the detection of the performance events (e.g., BBE, SES) is after any error correction. + +**3.1.1 errored block (EB):** A block in which one or more bits are in error. + +**3.1.2 severely errored second (SES):** A one-second period which contains $\geq 15\%$ errored blocks or at least one defect (see Notes 1 and 2). + +NOTE 1 – The defects and related performance criteria are listed in clause 7. + +NOTE 2 – To simplify measurement processes, the defect is used in the definition of SES instead of defining SES directly in terms of severe errors affecting the path. While this approach simplifies the measurement of SES, it should be noted that there may exist error patterns of severe intensity that would not trigger a defect as defined in clause 7. Thus, these would not be considered as an SES under this definition. If, in the future, such severe user-affecting events are found, this definition will have to be studied again. + +**3.1.3 background block error (BBE):** An errored block not occurring as part of an SES. + +**3.2 error performance parameters:** Error performance should only be evaluated whilst the path is in the available state. For a definition of the entry/exit criteria for the unavailable state, see [ITU-T G.827] and Annex A. + +In the following definitions, this Recommendation neither assumes nor requires that forward error correction (FEC) is used (see [ITU-T G.709]). However, if FEC is used, all the performance parameters and events are defined after FEC (i.e., post-FEC). In other words, the detection of the performance events (e.g., BBE, SES) is after any error correction. + +**3.2.1 severely errored second ratio (SESR):** The ratio of SES in available time to total seconds in available time during a fixed measurement interval. + +**3.2.2 background block error ratio (BBER):** The ratio of BBE in available time to total blocks in available time during a fixed measurement interval. The count of total blocks excludes all blocks during SESs. + +**3.3 generic definition of the block:** This Recommendation is based upon the error performance measurement of blocks consistent with an OTN hierarchy frame. This clause offers a generic definition of the term "block" as follows: + +A block is a set of consecutive bits associated with the path; each bit belongs to one, and only one, block. Consecutive bits may not be contiguous in time. + +**3.4 hypothetical reference optical path (HROP):** A hypothetical reference optical path is defined as the whole means of digital transmission of an ODUk digital signal (which is a digital signal of a specified rate given in [ITU-T G.709]), including the path overhead, between equipment at which the signal originates and terminates. An end-to-end hypothetical reference path spans a distance of 27'500 km. + +**3.5 ODUk path:** An ODUk path is a trail carrying an OPUk payload and associated OPUk and ODUk overhead through the layered optical transport network between the ODUk path terminating equipment. An ODUk path may be bidirectional or unidirectional and may comprise both customer-owned portions and network operator-owned portions. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------|--------------------------------------| +| AIS | Alarm Indication Signal | +| ATM | Asynchronous Transfer Mode | +| BBE | Background Block Error | +| BBER | Background Block Error Ratio | +| BDI | Backward Defect Indication | +| BEI | Backward Error Indication | +| BIP | Bit Interleaved Parity | +| BIS | Bringing into Service | +| BOD | Backbone Operator Domain | +| CBR | Constant Bit Rate | +| CSES | Consecutive Severely Errored seconds | +| EB | Errored Block | +| EDC | Error Detection Code | +| ES | Errored Second | +| FEC | Forward Error Correction | +| GFP | Generic Framing Procedure | +| HROP | Hypothetical Reference Optical Path | +| IAE | Incoming Alignment Error | +| IP | Internet Protocol | +| ISM | In-Service Monitoring | +| LCK | Locked Defect | + +| | | +|------|--------------------------------| +| LOD | Local Operator Domain | +| LOF | Loss of Frame Alignment | +| LOM | Loss of Multiframe Alignment | +| LOS | Loss of Signal | +| LTC | Loss of Tandem Connection | +| OCI | Open Connection Indication | +| ODUk | Optical Channel Data Unit-k | +| OG | Operator Gateway | +| OOS | Out-of-Service | +| OPUk | Optical Channel Payload Unit-k | +| OTN | Optical Transport Network | +| PEP | Path End Point | +| PLM | Payload Label Mismatch | +| ROD | Regional Operator Domain | +| SDH | Synchronous Digital Hierarchy | +| SES | Severely Errored Second | +| SESR | Severely Errored Second Ratio | +| STM | Synchronous Transport Module | +| TC | Tandem Connection | +| TCM | Tandem Connection Monitoring | +| TIM | Trace Identifier Mismatch | + +# 5 Measurement of the block + +## 5.1 In-service monitoring + +Each block is monitored by means of an inherent bit interleaved parity (BIP) error detection code (EDC) with a specified EDC usage. The EDC bits are physically separated from the block to which they apply. It is not normally possible to determine whether a block or its controlling EDC bits are in error. If there is a discrepancy between the EDC and its controlled block, it is always assumed that the controlled block is in error. + +The EDC for the ODUk path and ODUk TC is BIP-8. The block size for the ODUk path and ODUk TC is given in Table 8-1, and is equal to the number of bits in the ODUk frame (payload plus overhead). Note that the BIP-8 EDC is computed over the OPUk payload plus OPUk overhead bits, but not the ODUk overhead bits. The EDC Usage is $1 \times \text{BIP-8}$ . + +## 5.2 Out-of-service measurements + +Out-of-service measurements shall also be block-based. It is expected that the out-of-service error detection capability will be superior to the in-service capability described in clause 5.1. + +# 6 Performance monitoring at the near end and far end of a path + +By monitoring SES events for both directions at a single path end point, a network provider is able to determine the unavailable state of the path (see Annex A). In some cases, it is also possible to monitor the full set of error performance parameters in both directions from one end of the path. Specific in-service indicators for deriving far end performance of a path are listed in clause 7. + +# 7 Relationship between path performance monitoring and the block-based parameters + +## 7.1 General + +In addition to path performance monitoring, this clause covers tandem connection monitoring (TCM) as shown in Tables 7-1 to 7-3. ODUk path and ODUk tandem connection trails are equivalent from a performance perspective. The established rules for ODUk Path apply also to ODUk TC. Further details are given in [ITU-T G.709], [ITU-T G.798] and [ITU-T G.872]. + +### 7.1.1 Anomalies + +In-service anomaly conditions are used to determine the error performance of an ODUk path when the path is not in a defect state. The following anomaly is defined: + +a1 an EB as indicated by an EDC with the respective EDC usage. (See clause 5.1.) + +### 7.1.2 Defects + +In-service defect conditions defined in [ITU-T G.798] are used to determine the change of performance state which may occur on a path. Tables 7-1 and 7-2 show the defects used in this Recommendation. + +**Table 7-1 – Defects resulting in a near-end severely errored second** + +| Near-end defects (Notes 2, 3, 4) | | | +|----------------------------------|-----------------------|-------------------| +| Path termination | Non-intrusive monitor | Tandem connection | +| OCI (Note 1) | | OCI (Note 1) | +| AIS | | AIS | +| | | IAE | +| LCK | | LCK | +| | | LTC | +| PLM | | | +| TIM | | TIM | + +NOTE 1 – Paths not actually completed, e.g., during path set-up, will contain the ODUk-OCI (open connection indication) signal. + +NOTE 2 – The above defects are path defects only. Section defects such as OCh LOS, OTUk LOF, OTUk AIS, OTUk TIM, and OTM LOS give rise to an AIS defect in the path layers. + +NOTE 3 – When a near-end SES is caused by a near-end defect as defined above, the far-end performance event counters are not incremented, i.e., an error-free period is assumed. When a near-end SES results from $\geq 15\%$ errored blocks, the far-end performance evaluation continues during the near-end SES. This approach does not allow reliable evaluation of far-end data if the near-end SES is caused by a defect. It should be noted in particular that the evaluation of far-end events (such as SES or unavailability) can be inaccurate in the case where far-end SESs occur in coincidence with near-end SESs caused by a defect. Such inaccuracies cannot be avoided, but are negligible in practice because of the low probability of the occurrence of such phenomena. + +NOTE 4 – Refer to [ITU-T G.798] for defects contributing to performance monitoring in each trail termination sink function. + +**Table 7-2 – Defects resulting in a far-end severely errored second** + +| Far-end defects | | | +|------------------|-----------------------|-------------------| +| Path termination | Non-intrusive monitor | Tandem connection | +| BDI | BDI | BDI | + +## 7.2 Estimation of the performance parameters + +For ODUk transmission paths, the full set of performance parameters shall be estimated using the following events: + +**SES** An SES is observed when, during one second, at least 15% EBs, derived from anomaly a1, or one defect according to Tables 7-1 and 7-2, occur (see Table 7-3). + +**BBE** A BBE is observed when an anomaly a1 occurs in a block not being part of an SES. + +NOTE – The errored block threshold resulting in an SES is shown in Table 7-3 for each ODUk path type. + +**Table 7-3 – Threshold for the declaration of a severely errored second** + +| Bit rate (kbit/s) | Path type | Threshold for SES (Number of errored blocks in one second) | +|-----------------------------------|-----------|------------------------------------------------------------| +| 1 244 160 | ODU0 | 1 526 | +| 2 498 775 | ODU1 | 3 064 | +| 10 037 273 | ODU2 | 12 304 | +| 10 399 525 | ODU2e | 12 748 | +| 40 319 218 | ODU3 | 49 424 | +| 104 794 445 | ODU4 | 128 459 | +| Any bit rate $X \geq 1\ 244\ 160$ | ODUflex | $\text{ceiling}((150 \times X)/122\ 368)$ | + +## 7.3 Estimation of performance events at the far end of a path + +The following indications available at the near end or at an intermediate point along the path/tandem connection are used to estimate the performance events (occurring at the far end) for the reverse direction: + +- ODUk path/tandem connection BDI and BEI ([ITU-T G.709]). +- ODUk path/tandem connection BEIs are anomalies which are used to determine the occurrence of BBE and SES at the far end. +- ODUk path/tandem connection BDIs are defects which estimate the occurrence of SES at the far end. + +# 8 Error performance objectives + +## 8.1 End-to-end objectives + +Table 8-1 specifies the end-to-end objectives for a 27'500 km HROP in terms of the parameters defined in clause 3.2. The SESR and BBER objectives assume that the standardized ITU-T G.709 FEC is used. The actual objectives applicable to a real path are derived from Table 8-1 using the allocation principles detailed in clause 8.3. Each direction of the path shall independently satisfy the allocated objectives for all parameters. In other words, a path fails to satisfy this Recommendation if any parameter exceeds the allocated objective in either direction at the end of the given evaluation + +period. The objectives given in this Recommendation are understood to be long-term objectives to be met over an evaluation period of typically 30 consecutive days (1 month). + +**Table 8-1 – End-to-end error performance objectives +for a 27'500 km international ODUk HROP** + +| Nominal bit rate (kbit/s) | Path type
(Notes 1
and 2) | Blocks/s (Note 3) | SESR | BBER | +|-----------------------------------|------------------------------------------|----------------------------|-------------|----------------------| +| 1 244 160 | ODU0 | 10 168 | 0.002 | $2.5 \times 10^{-6}$ | +| $239/238 \times 2\,488\,320$ | ODU1 | 20 421 | 0.002 | $2.5 \times 10^{-6}$ | +| $239/237 \times 9\,953\,280$ | ODU2 | 82 026 | 0.002 | $2.5 \times 10^{-6}$ | +| $239/237 \times 10\,312\,500$ | ODU2e | 84 986 | 0.002 | $2.5 \times 10^{-6}$ | +| $239/236 \times 39\,813\,120$ | ODU3 | 329 492 | 0.002 | $2.5 \times 10^{-6}$ | +| $239/227 \times 99\,532\,800$ | ODU4 | 856 388 | 0.002 | $2.5 \times 10^{-6}$ | +| Any bit rate $X \geq 1\,244\,160$ | ODUflex | $(1000 \times X)/122\,368$ | 0.002 | $2.5 \times 10^{-6}$ | + +NOTE 1 – The block size for ODUk, k = 0, 1, 2, 2e, 3, 4, flex is equal to the ODUk frame size, which is $4 \times 3\,824 \times 8 = 122\,368$ bits. + +NOTE 2 – The EDC is BIP-8, and is computed over the OPUk payload ( $4 \times 3\,808 \times 8$ bits) plus OPUk overhead ( $4 \times 2 \times 8$ bits), for a total of $4 \times 3\,810 \times 8 = 121\,920$ bits. The EDC usage is $1 \times \text{BIP-8}$ . + +NOTE 3 – These values are rounded to the nearest upper unit. + +## 8.2 Hypothetical reference optical path + +The reference model in this Recommendation uses the notion of operator domains rather than national and international portions. Three types of domains are identified, the local operator domain (LOD), the regional operator domain (ROD), and the backbone operator domain (BOD). The boundary between the domains is called an operator gateway (OG). For correspondence with [ITU-T G.826] and [ITU-T G.828], the LOD and ROD are associated with the national portion, while the BODs are associated with the international portion. For continued consistency with [ITU-T G.826] and [ITU-T G.828], four BODs (one for each transit country) and two pairs of LOD-ROD are used for a total of eight (8) operator domains. The HROP, therefore, originates and terminates in the domain of a local operator; it traverses the domains of regional operators and backbone operators. + +The hypothetical reference optical path is a 27'500 km long path, spanning a total of 8 domains, as illustrated in Figure 3. + +![Diagram of a hypothetical reference optical path showing various operator domains (LOD, ROD, BOD) and Operator Gateways (OG) between two PEP points. The total distance is 27,500 km. A bracket indicates that there are a maximum of 4 backbone operator domains (BOD).](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +The diagram illustrates a hypothetical reference optical path between two PEP (Packet End Point) nodes. The path consists of several operator domains connected by Operator Gateways (OG). From left to right, the sequence is: LOD (Local Operator Domain), ROD (Regional Operator Domain), BOD (Backbone Operator Domain), BOD, ROD, and LOD. Each domain is represented by a cloud shape, and the connections between them are marked with OG (Operator Gateway) labels. A dashed line in the center indicates a break in the path. A horizontal dimension line at the bottom shows a total distance of 27,500 km. A bracket above the two BOD clouds is labeled 'Backbone operator domains (4 max)'. The text 'G.8201\_F03' is in the bottom right corner. + +OG Operator Gateway + BOD Backbone Operator Domain + LOD Local Operator Domain + ROD Regional Operator Domain + +Diagram of a hypothetical reference optical path showing various operator domains (LOD, ROD, BOD) and Operator Gateways (OG) between two PEP points. The total distance is 27,500 km. A bracket indicates that there are a maximum of 4 backbone operator domains (BOD). + +**Figure 3 – Hypothetical reference optical path** + +## 8.3 Allocation of end-to-end performance objectives + +For the three types of operator domains, the following block allocations apply: + +- a block allocation of 5% for a backbone operator domain; +- a block allocation of 5% for a regional operator domain; +- a block allocation of 7.5% for a local operator domain. + +An additional distance-based allocation is also given to each operator domain. This distance-based allocation is 0.2% per 100 km based on the product of the air route distance and a routing factor. The distance-based allocation is added to the block allocation to yield the total allocation for an operator domain. + +The routing factor is specified as follows for each operator domain (between OGs): + +- if the air route distance between two OGs is <1000 km, the routing factor is 1.5; +- if the air route distance is $\geq 1000$ km and <1200 km, the calculated route length is taken to be 1500 km; +- if the air route distance between two OGs is $\geq 1200$ km, the routing factor is 1.25. + +NOTE – A single operator may span several domains, such as one LOD, one ROD and one BOD. In this case, the allocation to the operator is the sum of the various domain allocations. + +## Annex A + +## Criteria for entry to and exit from the unavailable state + +(This annex forms an integral part of this Recommendation.) + +### A.1 Criteria for a single direction + +A period of unavailable time begins at the onset of ten consecutive SES events. These ten seconds are considered to be part of unavailable time. A new period of available time begins at the onset of 10 consecutive non-SES events. These ten seconds are considered to be part of available time. Figure A.1 illustrates the definition of criteria for transition to/from the unavailable state. + +![Figure A.1: Example of unavailability determination. A timeline diagram showing a sequence of seconds represented by boxes. A sequence of 10 consecutive grey boxes (SES) marks the start of a 'Period of unavailable time'. A subsequent sequence of 10 consecutive white boxes (Error-free) marks the start of a 'Period of available time'. A short sequence of boxes (some grey, some with an 'X') between the two periods indicates a transition. Labels include '10 s', '<10 s', 'Unavailability detected', and 'Availability detected'. A legend defines the box types: grey for SES, box with 'X' for ES (but not SES), and white for Error-free Second.](fc857414626a8d94d132e12d9afe52a4_img.jpg) + +Legend: + +- Severely Errored Second (SES) +- ⊠ Errored Second (ES) (but not an SES) +- Error-free Second + +Figure A.1: Example of unavailability determination. A timeline diagram showing a sequence of seconds represented by boxes. A sequence of 10 consecutive grey boxes (SES) marks the start of a 'Period of unavailable time'. A subsequent sequence of 10 consecutive white boxes (Error-free) marks the start of a 'Period of available time'. A short sequence of boxes (some grey, some with an 'X') between the two periods indicates a transition. Labels include '10 s', '<10 s', 'Unavailability detected', and 'Availability detected'. A legend defines the box types: grey for SES, box with 'X' for ES (but not SES), and white for Error-free Second. + +Figure A.1 – Example of unavailability determination + +NOTE – In the context of this annex, the term errored second (ES) is used not to denote a performance event but rather a one-second interval with at least one errored block. + +### A.2 Criterion for a bidirectional path + +A bidirectional path is in the unavailable state if either one or both directions are in the unavailable state. This is shown in Figure A.2. + +![Figure A.2: Example of the unavailable state of a path. A diagram showing three horizontal lines: 'Forward direction', 'Backward direction', and 'Path'. Grey rectangular blocks on the lines indicate periods of unavailability. Vertical dashed lines connect the start and end of these blocks across the three lines. A legend at the bottom shows a grey rectangle labeled 'Unavailable state'.](02ab1c6abcb5a2d487a30d019a5454b6_img.jpg) + +Legend: + +- Unavailable state + +Figure A.2: Example of the unavailable state of a path. A diagram showing three horizontal lines: 'Forward direction', 'Backward direction', and 'Path'. Grey rectangular blocks on the lines indicate periods of unavailability. Vertical dashed lines connect the start and end of these blocks across the three lines. A legend at the bottom shows a grey rectangle labeled 'Unavailable state'. + +Figure A.2 – Example of the unavailable state of a path + +### A.3 Criterion for a unidirectional path + +The criterion for a unidirectional path is defined in clause A.1 above. + +### **A.4 Consequences on error performance measurements** + +When a bidirectional path is in the unavailable state, SES and BBE counts may be collected in both directions and may be helpful in the analysis of the trouble. However, it is recommended that these SES and BBE counts are not included in estimates of SESR and BBER performance. + +Some existing systems may not support the above requirement. For these systems, the performance of a bidirectional path can be approximated by evaluating the parameters in each direction, independently of the state of availability of the other direction. It should be noted that this approximation method may result in a worse estimate of performance in the event that only one direction of a bidirectional path becomes unavailable. + +NOTE – This is not an issue for unidirectional paths. + +## Appendix I + +### Flow chart illustrating the recognition of anomalies, defects, errored blocks, and SES + +(This appendix does not form an integral part of this Recommendation.) + +![Flow chart illustrating the recognition of anomalies, defects, errored blocks, and SES](4356776ca004ecba5d599667a155d7d4_img.jpg) + +``` +graph TD; A([Monitored Second]) --> B{Defects?}; B -- Y --> D{Path in available State?}; B -- N --> C{Anomalies?}; C -- N --> End([End]); C -- Y --> E{%EB ≥ 15?}; E -- Y --> SES[SES]; E -- N --> D; E -- ES["ES (but not a SES)"] --> D; D -- N --> End; D -- Y --> F[cSES = cSES + 1]; F --> End; F --> G[cBBE = cBBE + EB(s)]; G --> End; +``` + +The flow chart starts with 'Monitored Second' (oval), leading to 'Defects?' (diamond). If 'Y' (Yes), it goes to 'Path in available State?' (diamond). If 'N' (No), it goes to 'Anomalies?' (diamond). If 'Anomalies?' is 'N', it goes to 'End' (oval). If 'Anomalies?' is 'Y', it goes to '%EB ≥ 15?' (diamond). If '%EB ≥ 15?' is 'Y', it goes to 'SES' (rectangle). If '%EB ≥ 15?' is 'N', it goes to 'Path in available State?' (diamond). If '%EB ≥ 15?' is 'ES (but not a SES)', it also goes to 'Path in available State?' (diamond). From 'Path in available State?' (diamond), if 'N', it goes to 'End' (oval). If 'Y', it goes to 'cSES = cSES + 1' (rectangle), which then goes to 'cBBE = cBBE + EB(s)' (rectangle), which finally goes to 'End' (oval). The label 'G.8201\_FI.1' is at the bottom right. + +Flow chart illustrating the recognition of anomalies, defects, errored blocks, and SES + +(See Notes) + +Figure I.1 – Flow chart illustrating the recognition of anomalies, defects, errored blocks, SES and BBE + +Notes to Figure I.1: + +NOTE 1 – In the context of this appendix, the term errored second (ES) is used not to denote a performance event, but rather a one-second interval with at least one errored block. + +NOTE 2 – The determination of unavailability time introduces a delay of 10 seconds. This delay should be considered when counting BBE and SES. + +NOTE 3 – cSES and cBBE represent counts of SES and BBE respectively. These counts are reset at the start of a measurement period. + +NOTE 4 – EB is the count of errored blocks within an ES whilst %EB represents the proportion of errored blocks within an ES compared to the number of blocks per second. + +NOTE 5 – ITU-T G.8201 parameters can be evaluated during, or at the end of, a measurement period P as follows, taking into account unavailable seconds (UAS): + +$$\text{BBER} = \text{cBBE} / [(P - \text{UAS}) \times \text{blocks per second}]$$ + +$$\text{SESR} = \text{cSES} / (P - \text{UAS})$$ + +NOTE 6 – In the simplified diagrams, no action is taken if the path is in the unavailable state. This is because the diagram does not consider the transition between availability states when, in fact, event counters must be modified. In practice, the status of a second (i.e., non-SES or SES) must always be determined before a test is made on the status of path availability. In other words, error events are always detected regardless of whether the path is available or not. Only the counting of events is inhibited during unavailability periods for the purposes of long-term performance monitoring. This process is reflected in the flow chart although consequent actions on changes of availability state are not. + +## Appendix II + +### Example of OTN layer network trails + +(This appendix does not form an integral part of this Recommendation.) + +Figure II.1 illustrates the role of the OTN in carrying various higher layer clients such as STM-N, and the supporting role of lower layer protocols such as the OTUk, OTSn, etc. + +![Diagram illustrating the transport of an STM-N signal in OTN. The diagram shows a path from a Client through various network elements including DXC, OTM0, LT, R, OCADM, and OCXC, with nested protocol layers like STM-N, ODUk, OCh, OTUk, OMSn, and OTSn. A legend defines the components: LT (Line terminal), OCADM (Optical channel add/drop multiplexer), OCXC (Optical channel cross-connect), 3R (O/E/O) (Re-amplification, re-shaping and re-timing), and R (Repeater).](523ab7b925beb555f88b2e1e1336974f_img.jpg) + +The diagram illustrates the transport of an STM-N signal through an OTN network. The signal path starts at a Client, passes through a DXC, then an OTM0 unit. It then enters a sequence of components: a Line Terminal (LT), a Repeater (R), another Repeater (R), an Optical Channel Add/Drop Multiplexer (OCADM), a 3R (O/E/O) unit, an Optical Channel Cross-Connect (OCXC), another 3R (O/E/O) unit, a Repeater (R), a Line Terminal (LT), and finally an OTM-n unit, ending at another DXC connected to an STM-N Client. The diagram shows nested protocol layers: STM-N (outermost), ODUk, OCh/OTUk, OMSn, and OTSn. The label G.8201(11)\_FII-1 is present in the bottom right. + +Legend: + +- LT: Line terminal +- OCADM: Optical channel add/drop multiplexer +- OCXC: Optical channel cross-connect +- 3R (O/E/O): Re-amplification, re-shaping and re-timing +- R: Repeater + +Diagram illustrating the transport of an STM-N signal in OTN. The diagram shows a path from a Client through various network elements including DXC, OTM0, LT, R, OCADM, and OCXC, with nested protocol layers like STM-N, ODUk, OCh, OTUk, OMSn, and OTSn. A legend defines the components: LT (Line terminal), OCADM (Optical channel add/drop multiplexer), OCXC (Optical channel cross-connect), 3R (O/E/O) (Re-amplification, re-shaping and re-timing), and R (Repeater). + +Figure II.1 – Example of the transport of an STM-N signal in OTN + +# Bibliography + +- [b-ITU-T M.2401] Recommendation ITU-T M.2401 (2003), *Error performance limits and procedures for bringing-into-service and maintenance of multi-operator international paths and sections within an optical transport network.* + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.822-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.822-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..aa99cb7392fdc3b08a51863f73b842088af80ae8 --- /dev/null +++ b/marked/G/T-REC-G.822-198811-I_PDF-E/raw.md @@ -0,0 +1,138 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' written across the center. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.822** + +**DIGITAL NETWORKS** + +--- + +**CONTROLLED SLIP RATE OBJECTIVES ON +AN INTERNATIONAL DIGITAL CONNECTION** + +**ITU-T Recommendation G.822** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.822 was published in Fascicle III.5 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **CONTROLLED SLIP RATE OBJECTIVES ON AN INTERNATIONAL DIGITAL CONNECTION** + +*(Geneva, 1980; further amended)* + +## **1 General** + +This Recommendation deals with end-to-end *controlled octet slip rate* objectives for 64-kbit/s international digital connections. The objectives are presented for various operational conditions in relation to the evaluation of connection quality. + +Under design conditions for digital network nodes and within defined normal transmission characteristics, it may be assumed that there are zero slips in a synchronized digital network. However, the defined transmission characteristics can be exceeded under operating conditions and cause a limited number of slips to occur even in a synchronized network. + +Under temporary loss of timing control within a particular synchronized network, additional slips may be incurred, resulting in a larger number of slips for an end-to-end connection. + +With plesiochronous operation, the number of slips on the international links will be governed by the sizes of buffer stores and the accuracies and the stabilities of the interconnecting national clocks. + +## **2 Scope and considerations** + +2.1 The end-to-end slip rate performance should satisfy the service requirements for telephone and non-telephone services on a 64-kbit/s digital connection in an ISDN. + +2.2 The slip rate objectives for an international end-to-end connection are stated with reference to the standard digital Hypothetical Reference Connection (HRX) of Figure 1/G.801 [1] of 27 500 km in length. + +2.3 It is assumed that international switching centres (ISC) are interconnected by international links which are operating plesiochronously, using clocks with accuracies as specified in Recommendation G.811. It is recognized that one slip in 70 days per plesiochronous interexchange link is the resulting maximum theoretical slip rate, taking into account clock accuracies according to Recommendation G.811 only, and provided that the performance of the transmission and switching requirements remain within their design limits. + +2.4 In the case where the connection includes all of the 13 nodes identified in the HRX (Recommendation G.801) and these nodes are all operating together in a plesiochronous mode, the nominal slip performance of a connection could be 1 in 70/12 days or 1 in 5.8 days. However, since in practice some nodes in such a connection would be part of the same synchronized network a better nominal slip performance can be expected (e.g. where the National Networks at each end are synchronized. The Nominal Slip Performance of the connection would be 1 in 70/4 or 1 in 17.5 days). + +*Note - These calculations assume a maximum of four international links.* + +2.5 In a practical international end-to-end connection containing both international and national portions, the slip rate may significantly exceed the value computed from $n$ plesiochronous interexchange links due to various design, environmental and operational conditions in international and national sections. These include: + +- a) configuration of the international digital network, +- b) national timing control arrangements, +- c) wander due to extreme temperature variations, +- d) operational performance characteristics of various types of switches and transmission links (including diurnal variations of satellite facilities), +- e) temporary disturbances on transmission and synchronization links (network rearrangements, protection switching, human errors, etc.). + +*Note - The maximum number, $n$ , of plesiochronous interexchange links is under study.* + +2.6 A threshold of slip performance is a suitable compromise between desired service requirements and normally achievable performance. Slip levels according to category (b) (see Table 1/G.822) exceeding this threshold will begin to affect performance and can cause some services to be considered degraded. In order to ensure that a trend of performance has been identified, the threshold rate must be measured over a sufficient period to record a significant number of slips. An objective limit is placed on the total time that the threshold is exceeded during the period of one year. The performance objectives are intended to represent a uniform set of specifications. + +Slip is one of several contributing factors to impairment of a digital connection. The performance objectives for the rate of octet slips on an international connection of 27 500 km in length or a corresponding bearer channel are given in Table 1/G.822. Further study is required to confirm that these values are compatible with other objectives, e.g. the error performance as listed in Recommendation G.821. + +TABLE 1/G.822 + +### **Controlled slip performance on a 64 kbit/s international connection or bearer channel** + +| Performance category | Mean slip rate | Proportion of time (Note 1) | +|----------------------|------------------------------------------------------|-----------------------------| +| (a)
(Note 2) | ≤ 5 slips in 24 hours | > 98.9 % | +| (b) | > 5 slips in 24 hours
and
≤ 30 slips in 1 hour | < 1.0 % | +| (c) | > 30 slips in 1 hour | < 0.1 % | + +Note 1 - Total time ≥ 1 year. + +Note 2 - The nominal slip performance due to plesiochronous operation alone is not expected to exceed 1 slip in 5.8 days (see § 2.4). + +## 3 Allocation of impairments + +3.1 The probability of more than one section of the network experiencing excessive slips which will simultaneously affect any given connection, is low. Advantage is taken of this factor in the allocation process. + +3.2 Because the impact of slips occurring in different parts of a connection will vary in importance depending upon the type of service and the level of traffic affected, the allocation process includes placing tighter limits on slips detected at international and national transit exchanges and less stringent limits on small local exchanges. + +3.3 The recommended allocation process is based on subdividing the percentage of time objectives for performance categories (b) and (c) (Table 1/G.822). A provisional allocation is made to the various portions of the HRX as shown in Table 2/G.822. + +TABLE 2/G.822 + +### **Allocation of controlled slip performance objectives** + +| Portion of HRX derived from Figure 1/G.801 [1] | Allocated proportion of each objective in Table 1/G.822 | Objectives as proportion of total time | | +|------------------------------------------------|---------------------------------------------------------|----------------------------------------|---------| +| | | (b) | (c) | +| International transit portion | 8.0 % | 0.08 % | 0.008 % | +| Each national transit portion (Note 2) | 6.0 % | 0.06 % | 0.006 % | +| Each local portion (Note 2) | 40.0 % | 0.4 % | 0.04 % | + +*Note 1* - The portions of the HRX are defined in Figure 1/G.822. They are derived from but not identical to Recommendation G.801. + +*Note 2* - The allocation between national transit portion and local portion is given for guidance only. Administrations are free to adopt a different apportionment provided the total for each national portion (local plus transit) does not exceed 46%. + +*Note 3* - Performance levels are defined in Table 1/G.822. + +*Note 4* - Total time $\geq$ one year. + +![Diagram showing the subdivision of the HRX into Local, National transit, and International transit portions. The sequence of elements is: T, LE, PC, SC, TC, ISC, ISC, ISC, ISC, ISC, TC, SC, PC, LE. The diagram is labeled CCITT-#3200.](1b896a95bc9974ad01fac7ac6f541a96_img.jpg) + +The diagram illustrates the sequence of elements in a digital transmission path, categorized into three portions: + + +- Local:** Includes the first LE (Line Equipment) and the last LE. +- National transit:** Includes the first PC (Packet Controller), SC (Switching Center), TC (Terminating Center), and the second PC, SC, and TC. +- International transit:** Includes the five ISC (Inter-switching Center) elements in the middle of the sequence. + + The sequence from left to right is: T, LE, PC, SC, TC, ISC, ISC, ISC, ISC, ISC, TC, SC, PC, LE. The diagram is labeled CCITT-#3200. + +Diagram showing the subdivision of the HRX into Local, National transit, and International transit portions. The sequence of elements is: T, LE, PC, SC, TC, ISC, ISC, ISC, ISC, ISC, TC, SC, PC, LE. The diagram is labeled CCITT-#3200. + +FIGURE 1/G.822 + +**Subdivision of the HRX for the purpose of allocation of slip performance objectives** + +## **Reference** + +[1] CCITT Recommendation *Digital transmission models*, Vol. III, Rec. 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over Transport aspects – Synchronization, quality +and availability targets + +SERIES Y: GLOBAL INFORMATION +INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, +NEXT-GENERATION NETWORKS, INTERNET OF +THINGS AND SMART CITIES + +Internet protocol aspects – Transport + +--- + +**Time and phase synchronization aspects of +telecommunication networks** + +Recommendation ITU-T G.8271/Y.1366 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| Ethernet over Transport aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Synchronization, quality and availability targets | G.8200–G.8299 | +| Service Management | G.8600–G.8699 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.8271/Y.1366 + +# Time and phase synchronization aspects of telecommunication networks + +## Summary + +Recommendation ITU-T G.8271/Y.1366 defines time and phase synchronization aspects in packet networks. It specifies the suitable methods to distribute the reference timing signals that can be used to recover the phase synchronization and/or time synchronization according to the required quality. + +The requirements for the synchronization characteristics that are specified in this Recommendation must be adhered to in order to ensure interoperability of equipment produced by different manufacturers and a satisfactory network performance. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.8271/Y.1366 | 2012-02-13 | 15 | 11.1002/1000/11527 | +| 1.1 | ITU-T G.8271/Y.1366 (2012) Amd. 1 | 2013-08-29 | 15 | 11.1002/1000/12033 | +| 1.2 | ITU-T G.8271/Y.1366 (2012) Amd. 2 | 2015-01-13 | 15 | 11.1002/1000/12391 | +| 2.0 | ITU-T G.8271/Y.1366 | 2016-07-07 | 15 | 11.1002/1000/12812 | +| 2.1 | ITU-T G.8271/Y.1366 (2016) Amd. 1 | 2017-08-13 | 15 | 11.1002/1000/13322 | +| 3.0 | ITU-T G.8271/Y.1366 | 2017-08-13 | 15 | 11.1002/1000/13383 | +| 3.1 | ITU-T G.8271/Y.1366 (2017) Amd. 1 | 2018-03-16 | 15 | 11.1002/1000/13549 | +| 3.2 | ITU-T G.8271/Y.1366 (2017) Amd. 2 | 2018-11-29 | 15 | 11.1002/1000/13767 | +| 4.0 | ITU-T G.8271/Y.1366 | 2020-03-15 | 15 | 11.1002/1000/14209 | + +## Keywords + +Methods and interfaces, time and phase synchronization requirements. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2020 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | | Page | +|------|---------------------------------------------------------------------------------------------------------|------| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Conventions ..... | 4 | +| 6 | The need for time and phase synchronization ..... | 4 | +| 7 | Time and phase synchronization methods ..... | 6 | +| 7.1 | Distributed PRTC ..... | 7 | +| 7.2 | Packet based methods with timing support of intermediate nodes..... | 8 | +| 8 | Network reference model ..... | 9 | +| 8.1 | Access section of HRM with PTP/native access IWF ..... | 11 | +| 9 | Time and phase synchronization interfaces ..... | 12 | +| | Annex A – One pulse-per-second (1PPS) time and phase synchronization interface specification..... | 13 | +| A.1 | 1PPS ITU-T V.11 interface ..... | 13 | +| A.2 | 1PPS 50 $\Omega$ phase synchronization measurement interface ..... | 20 | +| | Appendix I – Time and phase noise sources in time distribution chains..... | 21 | +| I.1 | Noise introduced by a primary reference time clock (PRTC)..... | 21 | +| I.2 | Noise introduced by a packet master clock function..... | 21 | +| I.3 | Noise introduced by a packet slave clock function ..... | 21 | +| I.4 | Noise introduced by a telecom transparent clock..... | 22 | +| I.5 | Noise introduced by a link..... | 22 | +| I.6 | Derivation of delay asymmetry ..... | 22 | +| I.7 | Characteristics of the noise sources..... | 24 | +| I.8 | Time error accumulation in a chain of clocks ..... | 26 | +| | Appendix II – Time and phase end application synchronization requirements..... | 27 | +| | Appendix III – Asymmetry compensation for use of different wavelengths..... | 31 | +| | Appendix IV – Link and network asymmetry compensation ..... | 32 | +| | Appendix V – Delay asymmetry resulting from interface rate change in PTP-unaware network elements ..... | 35 | +| | Appendix VI – Time synchronization aspects in TDD based mobile communication systems..... | 38 | +| VI.1 | An overview of radio-interference in TDD systems ..... | 38 | +| VI.2 | Signal frame format of TDD systems..... | 39 | +| VI.3 | Base station to base station interference..... | 40 | +| VI.4 | User equipment to user equipment interference..... | 41 | + +| | Page | +|----------------------------------------------|-------------| +| Appendix VII – Time scales ..... | 42 | +| VII.1 Time scales ..... | 42 | +| VII.2 Relationship between time scales ..... | 43 | +| Bibliography..... | 44 | + +## Recommendation ITU-T G.8271/Y.1366 + +# Time and phase synchronization aspects of telecommunication networks + +# 1 Scope + +This Recommendation defines time and phase synchronization aspects in telecommunication networks. It specifies the suitable methods to distribute the reference timing signals that can be used to recover the phase synchronization and/or time synchronization according to the required quality. It also specifies the relevant time and phase synchronization interfaces and related performance. + +The telecommunication networks that are in the scope of this Recommendation are currently limited to the following scenarios: + +- Ethernet ([IEEE 802.3] and [IEEE 802.1Q]); +- multiprotocol label switching (MPLS) ([IETF RFC 3031] and [ITU-T G.8110]); +- internet protocol (IP) ([IETF RFC 791] and [RFC 2460]); +- optical transport network (OTN) ([ITU-T G.709]). + +The physical layers that are relevant to this Recommendation are the Ethernet media types, as defined in [IEEE 802.3], and, for OTN, the optical OCh layer with optical transport network (OTU) frame as defined in [ITU-T G.709]. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.703] Recommendation ITU-T G.703 (2016), *Physical/electrical characteristics of hierarchical digital interfaces*. +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2016), *Interfaces for the optical transport network*. +- [ITU-T G.810] Recommendation ITU-T G.810 (1996), *Definitions and terminology for synchronization networks*. +- [ITU-T G.8110] Recommendation ITU-T G.8110/Y.1370 (2005), *MPLS layer network architecture*. +- [ITU-T G.8260] Recommendation ITU-T G.8260 (2020), *Definitions and terminology for synchronization in packet networks*. +- [ITU-T G.8261] Recommendation ITU-T G.8261/Y.1361 (2019), *Timing and synchronization aspects in packet networks*. +- [ITU-T G.8272] Recommendation ITU-T G.8272/Y.1367 (2018), *Timing characteristics of primary reference time clocks*. +- [ITU-T V.11] Recommendation ITU-T V.11/X.27 (1996), *Electrical characteristics for balanced double-current interchange circuits operating at data signalling rates up to 10 Mbit/s*. + +- [IEEE 802.1Q] IEEE 802.1Q-2018, *IEEE Standard for Local and metropolitan area networks – Bridges and Bridged Networks*. +[https://standards.ieee.org/standard/802\\_1Q-2018.html](https://standards.ieee.org/standard/802_1Q-2018.html) +- [IEEE 802.3] IEEE 802.3-2018, *IEEE Standard for Ethernet*. +[https://standards.ieee.org/standard/802\\_3-2018.html](https://standards.ieee.org/standard/802_3-2018.html) +- [IEEE 1588] IEEE 1588-2008, *IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems*. + +- [IETF RFC 791] IETF RFC 791 (1981), *Internet Protocol (IP)*. + +- [IETF RFC 2460] IETF RFC 2460 (1998), *Internet Protocol, Version 6 (IPv6) Specification*. + +- [IETF RFC 3031] IETF RFC 3031 (2001), *Multiprotocol Label Switching Architecture*. + + +## 3 Definitions + +The terms and definitions used in this Recommendation are contained in [ITU-T G.810], [ITU-T G.8260] and [IEEE 1588]. + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|---------|----------------------------------------------------| +| 1PPS | One Pulse Per Second | +| ARP | Antenna Reference Point | +| BIPM | International Bureau of Weights and Measures | +| BBU | Base Band Unit | +| CA | Carrier Aggregation | +| CDMA | Code Division Multiple Access | +| CoMP | Co-ordinated Multi-Point | +| CRC | Cyclic Redundancy Check | +| CU | Centralized Unit | +| DCF | Dispersion Compensating Fibre | +| DU | Distributed Unit | +| eNB | E-UTRAN Node B | +| EN-DC | E-UTRAN New radio – Dual Connectivity | +| ERA | Earth Rotation Angle | +| E-UTRAN | Evolved Universal Terrestrial Radio Access Network | +| FCS | Frame Check Sequence | +| FDD | Frequency Division Duplexing | +| FR1 | Frequency Range 1 | +| FR2 | Frequency Range 2 | +| GBAS | Ground Based Augmentation System | + +| | | +|---------|-------------------------------------------------------------------------------------| +| GLONASS | GLObalnaya NAVigazionnaya Sputnikovaya Sistema (Global Navigation Satellite System) | +| GMT | Greenwich Mean Time | +| gNB | 5G (NR) Node B | +| GNSS | Global Navigation Satellite System | +| GPS | Global Positioning System | +| HRM | Hypothetical Reference Model | +| HRPD | High Rate Packet Data | +| IP | Internet Protocol | +| IRNSS | Indian Regional Navigation Satellite System | +| IWF | Interworking Function | +| LTE | Long Term Evolution | +| LTE-A | Long Term Evolution – Advanced | +| MAC | Medium Access Control | +| MBMS | Multimedia Broadcast Multicast Service | +| MBSFN | MBMS based on Single Frequency Network | +| MIMO | Multiple Input Multiple Output | +| MRTD | Maximum Received Time Difference | +| M2M | Machine to Machine | +| NR | New Radio | +| NTP | Network Time Protocol | +| OTDOA | Observed Time Difference of Arrival | +| OTN | Optical Transport Network | +| PDV | Packet Delay Variation | +| PHY | Physical Layer Protocol | +| PON | Passive Optical Network | +| PRTC | Primary Reference Time Clock | +| PSN | Packet Switched Network | +| PTP | Precision Time Protocol | +| QZSS | Quasi-Zenith Satellite System | +| RTT | Radio Transmission Technology | +| RX | Receive | +| SBAS | Satellite Based Augmentation System | +| SI | International System of Units | +| SMTC | SSB Measurement Timing Configuration | +| SSB | Synchronization Signal Block | +| TAE | Time Alignment Error | + +| | | +|----------|-------------------------------------------------| +| TAI | International Atomic Time | +| TDD | Time Division Duplexing | +| TD-SCDMA | Time Domain Synchronized CDMA | +| T-BC | Telecom Boundary Clock | +| T-GM | Telecom Grandmaster | +| T-TC | Telecom Transparent Clock | +| T-TSC | Telecom Time Slave Clock | +| TX | Transmit | +| UDP | User Datagram Protocol | +| UE | User Equipment | +| UT | Universal Time | +| UTC | Universal Time Co-ordinated | +| UTRA | Universal Terrestrial Radio Access | +| WCDMA | Wideband CDMA | +| WDM | Wavelength-Division-Multiplexing | +| WiMAX | Worldwide Interoperability for Microwave Access | + +## 5 Conventions + +Within this Recommendation, the following conventions are used: The term precision time protocol (PTP) is the protocol defined by [IEEE 1588]. As an adjective, it indicates that the modified noun is specified in or interpreted in the context of [IEEE 1588]. + +# 6 The need for time and phase synchronization + +Time synchronization has traditionally been required to support billing and alarm functions (maintenance or fault isolation). In this context, synchronization must in general be accurate to within hundreds of milliseconds. + +Another time synchronization application is the monitoring of delays in Internet protocol (IP) networks. In this case, the requirement is accuracy to within some hundreds of microseconds (the actual requirement depends on the application). + +Stringent time synchronization requirements (i.e., in the range of a few microseconds) apply to the generation of signals over the air interface of some mobile systems, such as code division multiple access (CDMA)2000 or long term evolution frequency division duplexing (LTE FDD) unicast, when it is required to support synchronous CDMA2000 interworking. + +Phase synchronization is often needed to support requirements for the air interface of some mobile systems, as in the case of time division duplexing (TDD) systems (for instance, LTE TDD), or when supporting multimedia broadcast/multicast service (MBMS). Note that ordinary wideband CDMA (WCDMA) MBMS does not require accurate phase synchronization since it has been specified and designed to work properly in networks that satisfy the 50 ppb frequency accuracy requirement. This requirement, which is guaranteed by the WCDMA node synchronization function (see [b-3GPP TS 25.402]), limits phase drift to between 10 and 20 ms. But when MBMS is based on single-frequency network (MBSFN) mode, timing must be accurate to within a few microseconds. This is because identical waveforms are transmitted simultaneously from multiple cells. The signals from these cells are then combined as the multipath components of a single cell. Terminals must thus + +perceive the signals of an entire group of transmitting cells as though they came from a single cell. Therefore, all transmissions must be very tightly synchronized and deliver exactly the same content to each base station. + +The main requirements applicable at the output of the application (e.g., on the radio interface in the case of a wireless application) are summarized in Appendix II. + +Based on Table II.1, it is possible to classify the applications into classes of requirements, as shown in Table 1 below. + +NOTE – In the case of mobile applications as described in Table II.1, the requirements are generally expressed in terms of phase error between base stations. In the case of a centralized master, the requirement could be expressed as $\pm$ half of the accuracy requirement applicable to the specific technology. Table 1 presents the requirement in this format in order to allow the analysis of time error budgeting as distributed from a primary reference time clock (PRTC) towards the end application. + +**Table 1 – Time and phase requirement classes** + +| Class level of accuracy | Time error requirements (Note 1) | Typical applications (for information) | +|-------------------------|----------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | 500 ms | Billing, alarms. | +| 2 | 100 – 500 $\mu$ s | IP delay monitoring.
Synchronization signal block (SSB)-measurement timing configuration (SMTC) window. | +| 3 | 5 $\mu$ s | LTE TDD (large cell).
Synchronous Dual Connectivity (for up to 7 km propagation difference between eNBs/gNBs in FR1). (Note 2) | +| 4 | 1.5 $\mu$ s | UTRA-TDD, LTE-TDD (small cell), NR TDD, WiMAX-TDD (some configurations).
Synchronous dual connectivity (for up to 9 km propagation difference between eNBs/gNBs in FR1) (Note 2).
New radio (NR) intra-band non-contiguous and inter-band carrier aggregation, with or without multiple input multiple output (MIMO) or transmit (TX) diversity. | +| 5 | 1 $\mu$ s | WiMAX-TDD (some configurations). | +| 6 | x ns (Note 4) | Various applications, including location based services and some coordination features. (Note 3) | + +NOTE 1 – The requirement is expressed in terms of time error with respect to a common reference. Some of the original requirements were expressed in terms of relative time error. + +NOTE 2 – FR1: 410 MHz – 7.125 GHz; FR2: 24.25 – 52.6 GHz + +NOTE 3 – The performance requirements of some of these features are under study. For information purposes only, values between 500 ns and 1.5 $\mu$ s have been mentioned for some features. Depending on the final specifications developed by 3GPP, these applications may be handled in a different level of accuracy. + +NOTE 4 – For the value x, refer to Table 2 and Table II.2 of Appendix II. + +Based on Table II.2, it is possible to classify the class 6 level of accuracy into a further three sub-classes, as shown in Table 2. + +**Table 2 – Time and phase requirements for cluster based synchronisation** + +| Class level of accuracy | Maximum relative time error requirements (Note 1) | Typical applications (for information) | +|-------------------------|---------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 3A | 5 µs | LTE MBSFN. | +| 4A | 3 µs | NR intra-band non-contiguous (FR1 only) and inter-band carrier aggregation; with or without MIMO or TX diversity. | +| 6A | 260 ns | LTE intra-band non-contiguous carrier aggregation with or without MIMO or TX diversity, and inter-band carrier aggregation with or without MIMO or TX diversity.
NR intra-band contiguous (FR1 only) and Intra-band non-contiguous (FR2 only) carrier aggregation, with or without MIMO or TX diversity. | +| 6B | 130 ns | LTE intra-band contiguous carrier aggregation, with or without MIMO or TX diversity.
NR (FR2) intra-band contiguous carrier aggregation, with or without MIMO or TX diversity. | +| 6C
(Note 2) | 65 ns | LTE and NR MIMO or TX diversity transmissions, at each carrier frequency. | + +NOTE 1 – The maximum relative time error requirements represent the largest timing difference measured between any two elements of the cluster. See Appendix VII of [b-ITU-T G.8271.1] for illustration of how requirements are specified in a cluster. In 3GPP terminology this is equivalent to time alignment error (TAE). + +NOTE 2 – Level 6C is an internal equipment specification, and does not result in a synchronization requirement on the transport network. + +This Recommendation deals mainly with the class 4, 5, and 6A levels of accuracy requirement, as indicated in Table 2. + +# 7 Time and phase synchronization methods + +Packet-based methods (typically using the network time protocol (NTP)) without timing support from the network are traditionally used to support applications with less strict time and phase synchronization requirements (class 1 according to Table 1). + +This Recommendation focuses on applications corresponding to classes 4, 5, and 6 according to Table 1. + +For these applications, the following options are considered in this Recommendation: + +- a distributed primary reference time clock (PRTC) approach, implementing a global navigation satellite system (GNSS) receiver in the end application (a global positioning system (GPS) receiver, for example); +- packet-based methods with timing support of intermediate nodes. + +NOTE 1 – Additional solutions may be considered as a complement to the above solutions. As an example, timing may be carried over the radio interface of mobile systems. Applicability to the general hypothetical reference model (HRMs) is for further study. + +NOTE 2 – The use of packet-based methods with limited timing support, or without timing support of intermediate nodes, is considered capable of addressing applications corresponding to class 4. + +The following clauses provide details on the synchronization methods based on the distributed PRTC approach, and packet based methods with timing support of intermediate nodes. + +### 7.1 Distributed PRTC + +One method to achieve time and phase synchronization is to distribute a synchronization signal directly to each clock in the network. This method is referred to as a distributed primary reference time clock and, in general, is feasible with radio distribution because a network-wide wire-based distribution would require a complete extra network, which may be impractical. However, in some cases, a remote distribution of the PRTC signal via cables might also be possible. The radio distribution is normally achieved by means of GNSS, as for instance the GPS. Other radio systems may also be used. + +The main objective of a synchronization network is to synchronize the end applications which require a timing reference. If there are several end applications in one site, a single PRTC reference can be deployed in the site and the time/phase reference can be further distributed within the site from a centralized function. The details of the centralized function are for further study. + +Figure 1 below gives a generic representation of the distributed PRTC method. In the case of GNSS-based synchronization, the reference timing signal is distributed by the satellite signals and the GNSS receiver acts as the PRTC of the network. The receiver (RX) in Figure 1 processes the GNSS signal and extracts a reference signal for the end applications. + +![Diagram of a distributed PRTC synchronization network showing radio and cable distribution paths to end applications.](ddc7460821484f1ae2835c67955c554c_img.jpg) + +The diagram illustrates a distributed PRTC synchronization network. At the top, an oval labeled "Radio distributed PRTC, e.g., GNSS or distribution via cables" represents the source of the synchronization signal. Below this, there are three distinct synchronization paths. The first path shows a dashed line (radio) leading to an antenna, then a solid line (cable) to a box labeled "Rx", then a dashed line to a box labeled "End application". The second path shows a dashed line (radio) leading to an antenna, then a solid line (cable) to a box labeled "Rx", which then branches out via three dashed lines (radio) to three separate boxes labeled "End application". The third path shows a dashed line (radio) leading directly to a box labeled "End application". Horizontal dashed lines labeled "PRTC limits" are shown between the "Rx" boxes and the "End application" boxes. A legend at the bottom indicates that a dashed line with an arrow represents "Time or phase synchronization distribution via cable" and a dashed line with a lightning bolt symbol represents "Time or phase synchronization distribution via radio". The text "G.8271-Y.1366(12)\_F01" is in the bottom right corner. + +Diagram of a distributed PRTC synchronization network showing radio and cable distribution paths to end applications. + +**Figure 1 – Example of a distributed PRTC synchronization network** + +#### 7.1.1 Main characteristics + +One of the main advantages for a distributed PRTC approach is that the reference timing signals are available world-wide in the case of GNSS. This approach also allows for a flat distribution hierarchy with no risk of timing loops. In general, the overall network planning is also easier. + +The main disadvantages of this approach are the dependency on the operator of the navigation system, the requirements for an antenna with a wide-angle view to the sky, the need to address lightning protection and, in general, the issues related to the antenna cabling. + +Finally, GNSS-based systems present a risk of interference, e.g., by television (TV) systems, saturation and jamming. + +It should be mentioned, however, that evolution of the technology reduces some of the main drawbacks (e.g., installation, reliability, etc.). Moreover, it should be possible to secure the GNSS + +receivers, for instance when an accurate frequency reference, such as a synchronous Ethernet signal, is available. The options for securing GNSS receivers are for further study. + +In terms of performance, the accuracy that can be achieved by means of a PRTC system is defined in [ITU G.8272]. + +### 7.2 Packet based methods with timing support of intermediate nodes + +Time synchronization can be distributed via timing protocols such as PTP (see [IEEE 1588]). This Recommendation currently focuses on the cases where the timing reference is carried with support from the network. + +The timing support in the intermediate nodes (e.g., Ethernet switches) concerns specific hardware as well as software timing functions (see Figure 2). + +![Diagram illustrating a packet-based method with support from network nodes. A Telecom Grandmaster (T-GM) sends PTP messages (represented by green rectangles) to a network of Telecom Boundary Clocks (T-BC). The T-BCs are interconnected and also receive PTP messages. One T-BC is connected to an End application. The diagram shows the flow of PTP messages from the T-GM through the T-BC network to the End application.](a26e142d3df5bef41a84a9dd099d7825_img.jpg) + +The diagram shows a Telecom Grandmaster (T-GM) on the left sending PTP messages (green rectangles) to a network of Telecom Boundary Clocks (T-BC). The T-BCs are interconnected and also receive PTP messages. One T-BC is connected to an End application on the right. The diagram shows the flow of PTP messages from the T-GM through the T-BC network to the End application. A legend at the bottom left indicates that green rectangles represent PTP messages. The diagram is labeled G.8271-Y.1366(16)\_F02. + +Diagram illustrating a packet-based method with support from network nodes. A Telecom Grandmaster (T-GM) sends PTP messages (represented by green rectangles) to a network of Telecom Boundary Clocks (T-BC). The T-BCs are interconnected and also receive PTP messages. One T-BC is connected to an End application. The diagram shows the flow of PTP messages from the T-GM through the T-BC network to the End application. + +**Figure 2 – Example of packet-based method with support from network nodes** + +In the case of PTP, these functions can correspond either to the telecom boundary clock (T-BC) or to the telecom transparent clock (T-TC), with hardware timestamping at the related interfaces. + +The T-BC terminates and regenerates timestamp messages. + +The T-TC provides a means of measuring the delays that have been added by the network element and by the links connected to the network element. This Recommendation considers only T-BC support in this version. The use of T-TC in telecom applications is for further study. + +The Figure 3 shows an example of phase/time synchronization distributed via packet-based methods with timing support from the network. A packet master clock function in a telecom grandmaster (T-GM) having access to a reference timing signal compliant with the PRTC limits originates the packet timing distribution, and every transport node implements a T-BC. + +![Diagram illustrating time synchronization distribution via packet-based methods. At the top, a 'Radio distributed PRTC, e.g., GNSS or distribution via cables' provides a reference signal. This signal is received by an 'Rx' unit, which outputs 'PRTC limits'. Below the 'Rx' unit, the diagram shows two parallel distribution paths. The left path starts with an 'End application' and a 'Packet master clock'. The 'Packet master clock' feeds into a 'Packet timing distribution network' containing two 'Transport node' units, each marked with a 'T-BC' symbol. These nodes feed into 'Packet slave clock' units, which in turn feed into two 'End application' units. The right path starts with a 'Packet master clock' that feeds into a 'Packet timing distribution network' containing one 'Transport node' unit, marked with a 'T-BC' symbol. This node feeds into a 'Packet slave clock' unit, which feeds into two 'End application' units. A legend at the bottom indicates that dashed lines represent 'Time or phase synchronization distribution via cable' and dashed lines with an arrowhead represent 'Time or phase synchronization distribution via radio'. The diagram is labeled 'G.8271-Y.1366(12)_F03'.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +Diagram illustrating time synchronization distribution via packet-based methods. At the top, a 'Radio distributed PRTC, e.g., GNSS or distribution via cables' provides a reference signal. This signal is received by an 'Rx' unit, which outputs 'PRTC limits'. Below the 'Rx' unit, the diagram shows two parallel distribution paths. The left path starts with an 'End application' and a 'Packet master clock'. The 'Packet master clock' feeds into a 'Packet timing distribution network' containing two 'Transport node' units, each marked with a 'T-BC' symbol. These nodes feed into 'Packet slave clock' units, which in turn feed into two 'End application' units. The right path starts with a 'Packet master clock' that feeds into a 'Packet timing distribution network' containing one 'Transport node' unit, marked with a 'T-BC' symbol. This node feeds into a 'Packet slave clock' unit, which feeds into two 'End application' units. A legend at the bottom indicates that dashed lines represent 'Time or phase synchronization distribution via cable' and dashed lines with an arrowhead represent 'Time or phase synchronization distribution via radio'. The diagram is labeled 'G.8271-Y.1366(12)\_F03'. + +**Figure 3 – Example of time synchronization distributed via packet based methods** + +#### 7.2.1 Main characteristics + +The main advantage of a time synchronization distribution solution via packet-based methods is the significantly reduced number of GNSS receivers. Note that if the PRTC is based on GNSS, then GNSS receivers would be required at the PRTC locations. + +Among the disadvantages, it can be noted that the network planning is in this case more complex (e.g., with risk of timing loops). In addition, noise accumulation has also to be taken into account. Finally, another issue with this methodology is the time error due to asymmetries in the network that needs to be controlled (e.g., implying calibration of fibre lengths). + +## 8 Network reference model + +Figure 4 describes the network reference model used to define the time and phase synchronization performance objectives when the reference timing signal is carried over the transport network: + +![Figure 4 – Network reference model. The diagram shows a sequence of components: Network time reference (e.g., GNSS engine) connected to a PRTC (Primary reference time clock). The PRTC output (A) connects to a Packet master clock. The Packet master clock output (B) connects to a Packet network. The Packet network output (C) connects to a Packet slave clock. The Packet slave clock output (D) connects to an End application time clock. The End application time clock output (E) is the final output. A dashed line indicates a Packet timing signal path from the Packet master clock through the Packet network to the Packet slave clock. A legend indicates that solid lines represent Physical timing signals (for phase and/or time synchronization) and dashed lines represent Packet timing signals. A detailed view of the Packet network shows it is composed of a Transport part and an Access part. The diagram is labeled G.8271-Y.1366(16)-Amd.1(17)_F04.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Figure 4 – Network reference model. The diagram shows a sequence of components: Network time reference (e.g., GNSS engine) connected to a PRTC (Primary reference time clock). The PRTC output (A) connects to a Packet master clock. The Packet master clock output (B) connects to a Packet network. The Packet network output (C) connects to a Packet slave clock. The Packet slave clock output (D) connects to an End application time clock. The End application time clock output (E) is the final output. A dashed line indicates a Packet timing signal path from the Packet master clock through the Packet network to the Packet slave clock. A legend indicates that solid lines represent Physical timing signals (for phase and/or time synchronization) and dashed lines represent Packet timing signals. A detailed view of the Packet network shows it is composed of a Transport part and an Access part. The diagram is labeled G.8271-Y.1366(16)-Amd.1(17)\_F04. + +**Figure 4 – Network reference model** + +The following reference points are defined. All the requirements related to these reference points are defined with respect to a common time reference, i.e., any recognized time reference such as GPS time. + +- A: PRTC output; +- B: Packet master clock output; +- C: Packet slave clock input; +- D: Packet slave clock output; +- E: End application output. + +Some specific access technologies may need to be considered in the network reference model in some cases. For instance, the network between points B and C can be composed in some cases of a transport part and an access part. Each part would then have its own phase/time budget derived from the media specific mechanisms that have been developed to transport frequency and time synchronization. + +NOTE 1 – In Figure 4 the packet master clock could correspond to a T-GM and the packet slave clock could correspond to a telecom time slave clock (T-TSC). + +NOTE 2 – The performance studies documented in [b-ITU-T G.8271.1] are based on a full timing support in the network with hardware timestamping (e.g., T-BC in every node in the case of [IEEE 1588]) and with physical layer frequency synchronization support (e.g., synchronous Ethernet support). The case of partial timing support, where some or all of the nodes are not capable of providing timing support to the PTP layer, is covered in [b-ITU-T G.8271.2]. + +NOTE 3 – In some cases, specific access technologies may need to be considered in the network reference model. For instance in some cases, the packet network between points B and C can be composed of a transport part and an access part. Each part would then have its own phase/time budget. In some radio access networks (RAN) scenarios, for instance when the RAN is split based on different radio functions, from the point of view of timing, the starting point for the RAN may be present between points B and C shown in Figure 4. Alternatively, the entire network model may be present within the RAN. Details are for further study. + +NOTE 4 – Additional detail for the network reference model of Figure 4 for the case of PTP over non-packet technologies (e.g., OTN, gigabit passive optical network (GPON), microwave) is for further study. + +The overall budget relates to measurement point 'E' (i.e., the time error at E with respect to the common time reference). + +'A', 'B', 'C' and 'D' define the other relevant measurement reference points and related network limits, that also indicate the budget of the noise that can be allocated to the relevant network segments (e.g., 'A to C', 'A to D', etc.). + +The measurement points that are of interest for a specific application may depend on where the network administrative domain borders apply. + +Also, as described above, the measurement in some cases needs to be performed on a two-way timing signal, which would require a specific test set-up and metrics to be used. + +The measurement set-up for two-way timing signals as well as the noise that can be added by the measurement test equipment is an item for further study. + +Another possibility is to perform the measurement using an external dedicated output phase/time reference, such as a one pulse per second (1PPS) interface. Annex A provides guidance about this type of interface. + +### 8.1 Access section of HRM with PTP/native access IWF + +The general network reference model in Figure 4 can be further expanded to illustrate different types of access technology that may be used at the edge of the network such as microwave, digital subscriber line (DSL) or passive optical network (PON). + +Generally access technologies can be categorized as either point-to-multipoint shared technologies or point-to-point technologies. An example of a point-to-multipoint shared media technology is a PON with a single multi-port head end and multiple end devices. An example of a point to point technology is a microwave system. Figure 5 expands the access section to show the media conversion that occurs between the Ethernet technology that forms the existing synchronization HRM of the transport section and the technologies in the access section of the HRM. The time error budget of this section may depend on the specific type of technology. + +![Figure 5 – Network reference model with access section. The diagram shows a network reference model with several components and interfaces. At the top, a 'Network time reference (e.g., GNSS engine)' is connected to a 'PRTC' (Primary reference time clock). The PRTC is connected to a 'Packet master clock' at interface A. The Packet master clock is connected to a 'Packet network' at interface B.0. The Packet network is connected to a 'Packet slave clock' at interface C. The Packet slave clock is connected to an 'End application time clock' at interface D. Below the Packet network, there is a 'Transport section' and an 'Access section' at interface B.1. The Transport section is connected to the Packet network at B.0 and to the Access section at B.1. The Access section is connected to the Packet slave clock at C. Below the Access section, there is a detailed view of the 'Access section' which includes a 'PTP-Medium IWF', an 'Access medium', and a 'Medium-PTP IWF'. The PTP-Medium IWF is connected to the Transport section at B.1 and to the Access medium. The Access medium is connected to the Medium-PTP IWF. The Medium-PTP IWF is connected to the Packet slave clock at C. A legend indicates that solid lines represent 'Physical timing signal (for phase and/or time synchronization)' and dashed lines represent 'Packet timing signal'. The diagram is labeled 'G.8271-Y.1366(16)-Amd.1(17)_F05'.](21ad58fee90f2be50708ff541d225507_img.jpg) + +Figure 5 – Network reference model with access section. The diagram shows a network reference model with several components and interfaces. At the top, a 'Network time reference (e.g., GNSS engine)' is connected to a 'PRTC' (Primary reference time clock). The PRTC is connected to a 'Packet master clock' at interface A. The Packet master clock is connected to a 'Packet network' at interface B.0. The Packet network is connected to a 'Packet slave clock' at interface C. The Packet slave clock is connected to an 'End application time clock' at interface D. Below the Packet network, there is a 'Transport section' and an 'Access section' at interface B.1. The Transport section is connected to the Packet network at B.0 and to the Access section at B.1. The Access section is connected to the Packet slave clock at C. Below the Access section, there is a detailed view of the 'Access section' which includes a 'PTP-Medium IWF', an 'Access medium', and a 'Medium-PTP IWF'. The PTP-Medium IWF is connected to the Transport section at B.1 and to the Access medium. The Access medium is connected to the Medium-PTP IWF. The Medium-PTP IWF is connected to the Packet slave clock at C. A legend indicates that solid lines represent 'Physical timing signal (for phase and/or time synchronization)' and dashed lines represent 'Packet timing signal'. The diagram is labeled 'G.8271-Y.1366(16)-Amd.1(17)\_F05'. + +**Figure 5 – Network reference model with access section** + +For example, between B.0 and B.1 the transport section consists of a network chain from [b-ITU-T G.8271.1] comprised of full timing aware ITU-T G.8273.2 T-BCs using PTP & SyncE. Between B.1 and C of the access section, there may also be T-BCs, and in this case they are connected to and from native access clocks. These native access clocks provide the direct connection to the medium. Essentially, the T-BC and native access clock provides an interworking function (IWF) that converts between Ethernet carrying PTP and the access medium. + +The access section will have a time error that is a combination of the constant and dynamic components of the medium as well as contribution from the clocks in the access section. + +## 9 Time and phase synchronization interfaces + +Time and phase synchronization interfaces are needed for the following two purposes: + +### 1) measurement interface: + +in order to allow network operators to measure the quality of the time/phase synchronization distributed along a synchronization chain, each PRTC, T-GM, T-BC and T-TSC must have a dedicated external phase/time output interface implemented; + +a one pulse-per-second (1PPS) interface is an adequate measurement interface, and should be implemented according to one of the interfaces specified in Annex A. Additional measurements interfaces are for further study. + +### 2) distribution interface: + +time and phase synchronization interfaces are sometimes needed to connect systems belonging to a time/phase synchronization distribution chain; + +a typical application is the case of a T-TSC connected to an end-application, such as a base station, which is equipped with an existing input 1PPS interface. The details of the distribution interfaces are for further study. + +Figure 6 shows examples of both types of time and phase synchronization interfaces: measurement interfaces (reference point 1) and distribution interfaces (reference point 2). Different requirements may apply to these points. + +![Diagram of a synchronization chain showing measurement and distribution interfaces.](3fa8bfee86764e3c3a1a6fbbe61bbd52_img.jpg) + +The diagram illustrates a synchronization chain starting with a PRTC (Primary Reference Time Clock) at the top left. An arrow labeled '1' points out from the PRTC to the right, representing a measurement interface. Below the PRTC, a vertical arrow points down to a T-GM (Timing Generator). From the T-GM, a horizontal line extends to the right, connecting to a series of four T-BC (Timing Boundary Clock) units. Below each T-BC unit, a dashed vertical arrow points down to a '1', representing measurement interfaces. The last T-BC unit connects to a T-TSC (Timing Synchronization Clock). Below the T-TSC, a dashed vertical arrow points down to a '1', representing another measurement interface. Above the T-TSC, a solid vertical arrow points up to a triangle labeled 'End application', with the number '2' next to it, representing a distribution interface. The text 'G.8271-Y.1366(16)\_F06' is located at the bottom right of the diagram. + +Diagram of a synchronization chain showing measurement and distribution interfaces. + +**Figure 6 – Possible locations of external time and phase interfaces in a chain of telecom-boundary clocks** + +# Annex A + +## One pulse-per-second (1PPS) time and phase synchronization interface specification + +(This annex forms an integral part of this Recommendation.) + +### A.1 1PPS ITU-T V.11 interface + +The 1PPS time/phase interface uses a point-to-point ITU-T V.11 interface as specified in [ITU-T V.11] with an additional requirement on the rise/fall times of the 1PPS signal as defined in [ITU-T G.703]. This is needed to provide the accuracy required for the 1PPS signal. + +This interface can be used for time synchronization distribution as well as for time measurement. + +The interface is a balanced interface that can tolerate significant common mode noise. + +The 1PPS interface consists of a balanced 100 ohm 1PPS differential signal that can be used to connect to the next clock or to measurement equipment. + +![Diagram of a balanced 1PPS V.11 interface showing a DRIVER connected to a RECEIVER via a TWISTED CABLE. The DRIVER has PPS_OUT and TX+/TX- outputs. The RECEIVER has PPS_IN and RX+/RX- inputs. A 100 ohm load is connected across the PPS_IN+ and PPS_IN- inputs. A performance measurement point is indicated on the cable near the DRIVER. The cable length is labeled L.](40f30e4d577a17052f8b1e6dc802a0d8_img.jpg) + +The diagram illustrates a balanced 1PPS V.11 interface. On the left, a yellow block labeled 'DRIVER' has two output pairs: 'PPS\_OUT' (indicated by an arrow) and 'TX+/TX-' (indicated by '+' and '-' signs). The 'DRIVER' is connected to ground. The 'TX+/TX-' outputs are connected to a blue connector labeled 'CONN'. A red circle highlights a 'Performance measurement point' on the cable just after the first connector. The cable is labeled 'TWISTED CABLE' and has a length 'L' indicated by a dashed line between the two connectors. The second 'CONN' is connected to a yellow block labeled 'RECEIVER'. The 'RECEIVER' has two input pairs: 'PPS\_IN' (indicated by an arrow) and 'RX+/RX-' (indicated by '+' and '-' signs). A '100 ohm load' is connected across the 'PPS\_IN+' and 'PPS\_IN-' inputs. The 'RECEIVER' is also connected to ground. The text 'G.8271-Y.1366(12)-Amd.1(13)\_FA.1' is at the bottom right. + +Diagram of a balanced 1PPS V.11 interface showing a DRIVER connected to a RECEIVER via a TWISTED CABLE. The DRIVER has PPS\_OUT and TX+/TX- outputs. The RECEIVER has PPS\_IN and RX+/RX- inputs. A 100 ohm load is connected across the PPS\_IN+ and PPS\_IN- inputs. A performance measurement point is indicated on the cable near the DRIVER. The cable length is labeled L. + +Figure A.1 – Balanced 1PPS V.11 interface + +#### A.1.1 Interface signals + +The signals of this interface are defined in this clause as follows: + +- 1PPS\_OUT+/1PPS\_OUT-: This output signal pair indicates the significant event occurring on the leading edge of the signal and is generated by the time master; +- 1PPS\_IN+/1PPS\_IN-: This input signal pair indicates the significant event occurring on the leading edge of the signal and is used by the time slave; +- TX+/TX-: This output signal pair is used for a serial communication channel for transfer of time messages and status messages between the time master and the time slave; +- RX+/RX-: This input signal pair is used for a serial communication channel for transfer of messages between the time master and the time slave. + +The connector is defined in [ITU-T G.703], which specifies the physical aspects of this interface. + +The connection requires the use of a crossed cable that connects the signal pairs as specified in Table A.1. + +Table A.1 – Cable connections + +| Connector A | Connector B | +|---------------------|---------------------| +| 1PPS_OUT+/1PPS_OUT- | 1PPS_IN+/1PPS_IN- | +| 1PPS_IN+/1PPS_IN- | 1PPS_OUT+/1PPS_OUT- | +| TX+/TX- | RX+/RX- | +| RX+/RX- | TX+/TX- | + +**Table A.1 – Cable connections** + +NOTE – Not all the signals in Table A.1 will necessarily be needed at the same time (e.g., one direction only might be sufficient in some cases). The backward direction of the messaging channel is for further study. + +#### **A.1.2 Automatic cable delay compensation (optional)** + +The 1PPS ITU-T V.11 interface can optionally support automatic cable delay compensation. The enhanced 1PPS ITU-T V.11 interface adds support for automatic cable and ITU-T V.11 transceiver compensation using a feedback loop that allows the time master to measure the round-trip delay of the 1PPS signal and compensate for the path delay when generating the 1PPS signal. + +The 1PPS signal is initially generated by the timing master at the 1-second boundary, T1. This signal is delayed through the cable before it arrives at the timing slave. The 1PPS signal is looped back at the slave and sent to the time master. The time master captures the time of reception of the 1PPS signal from the time slave, T2, and measures the round-trip delay as the time since the generation of the 1PPS signal. + +Assuming that the path is symmetrical, the time master calculates the mean cable delay as: $(T2 - T1)/2$ and either compensates for the cable delays by advancing the 1PPS signal by the mean cable delay or alternatively informs the time slave about the mean cable delay through the ITU-T V.11 serial communication channel so that the slave can perform the compensation. + +The protocol used on the serial communication channel is defined in clause A.1.3 below. + +The time slave performs a loopback of the 1PPS signal at some point after the ITU-T V.11 transceiver. + +#### **A.1.3 Serial communication channel** + +##### **A.1.3.1 Transmission characteristics** + +The following characteristics apply to the serial communication channel: + +- 1) the default baud rate is 9600, without parity check; +- 2) when every byte data is sent, it shall include one start bit denoted by low voltage level, eight bits data and one end bit denoted by high voltage level. During non-data interval, it should be kept at high voltage level; +- 3) the message data should be sent no sooner than 1ms after the rising edge of 1PPS and must be finished within 500 ms; +- 4) the message represents the time at which the current 1PPS starts; +- 5) the messages should be sent once per second. + +##### **A.1.3.2 Message structure** + +The message structure is defined in Figure A.2. + +![Diagram of Time of day message structure showing fields: SYNC CHAR 1, SYNC CHAR 2, CLASS, ID, LENGTH, PAYLOAD, and FCS. Annotations show 'Length' for PAYLOAD and 'Check sum' for CLASS, ID, LENGTH, and PAYLOAD.](1bf34e86af3591c80bfbc1c318f811c0_img.jpg) + +The diagram illustrates the structure of a time of day message. It consists of seven fields: SYNC CHAR 1, SYNC CHAR 2, CLASS, ID, LENGTH, PAYLOAD, and FCS. A bracket labeled 'Length' spans the PAYLOAD field. A bracket labeled 'Check sum' spans the CLASS, ID, LENGTH, and PAYLOAD fields. The text 'G.8271-Y.1366(16)\_FA.2' is located at the bottom right of the diagram. + +Diagram of Time of day message structure showing fields: SYNC CHAR 1, SYNC CHAR 2, CLASS, ID, LENGTH, PAYLOAD, and FCS. Annotations show 'Length' for PAYLOAD and 'Check sum' for CLASS, ID, LENGTH, and PAYLOAD. + +**Figure A.2 – Time of day message structure** + +Each message is a multiple of 8 bits (octets) with frame check sequence (FCS). The messages are identified by the message CLASS and message ID. The transmission order of octets within multi-octet fields should comply with "big endian" rules, i.e., from the most significant octet first to the least significant octet last. The transmission of bits within one octet should be from bit 0 to bit 7. The transmission of the payload should start from offset 0 (see Tables A.3, A.5 and A.7). + +Multiple messages may be sent on the serial communications channel. The messages can be sent with either no delay between messages or with a non-zero delay between messages. However the transmission of all messages must be completed within the time period indicated in clause A.1.3.1. + +The interpretation of each message field is as follows: + +###### 1) start of message: + +The start of a message has two octets: SYNC CHAR 1 and SYNC CHAR 2. These two octets are used for message alignment. A common value of 0x43 and 0x4D has been given to each octet representing the ASCII characters "C" and "M" respectively. + +###### 2) header: + +The message header includes the sub-fields CLASS (1 octet) and message ID (1 octet). CLASS shows the basic type of the message. ID is encoded as the subtype of each class of message. + +###### 3) length: + +The length field has two octets which indicates the length of the payload (not including the length of Sync Char 1, Sync Char 2, Header, Length and FCS field). + +###### 4) payload: + +The payload field contains the contents of the message. This field may vary in length, depending on the message type. + +###### 5) FCS: + +The FCS has one octet, consisting of a cyclic redundancy check (CRC)-8 calculated over the header, length and payload fields of each message type (excluding Sync Chars 1 and 2). The CRC-8 uses the generator polynomial $G(x) = x^8 + x^5 + x^4 + 1$ , and is calculated as follows: + +- the input bits are taken in network transmission order, i.e., the most significant octet first, and within each octet the least significant bit first, to form an $N$ -bit pattern representing the coefficients of a polynomial $M(x)$ of degree $N-1$ (where $N$ is the number of bits in the message); +- $M(x)$ is pre-pended with the hexadecimal value 0xFC, then multiplied by $x^8$ . The result is then divided (modulo 2) by $G(x)$ , producing a remainder $R(x)$ ; +- the coefficients of $R(x)$ are considered to be an 8-bit sequence, where $x^7$ is the most significant bit; +- this 8-bit sequence is the CRC-8 where the first bit of the CRC-8 to be transmitted is the coefficient of $x^7$ and the last bit transmitted is the coefficient of $x^0$ . + +The de-mapper process performs the above calculation in the same manner as the mapper process, except that here, the $M(x)$ polynomial of step (a) includes the CRC-8 bits of the FCS field, resulting in $M(x)$ having degree $N+7$ . In the absence of bit errors, the remainder shall be 0000 0000. + +Alternatively, the de-mapper may exclude the FCS field in which case, in the absence of bit errors, the remainder shall be equal to the value of the FCS field. + +Figure A.3 shows an example of a time-of-day time event message. Using the CRC-8 calculation method defined above, the calculated CRC-8 value in network transmission order is 1010 0100. Represented as an octet field, the FCS value is 0x25. + +NOTE – In step (b), the polynomial $M(x)$ is pre-pended with the value 0xFC. In the optimized implementation used by most actual CRC-generators, this is the mathematical equivalent of setting the initial value to 0xFF for the generator polynomial defined, but without pre-pending the value 0xFC. + +| Field | Sync Char 1 | Sync Char 2 | Class | ID | Length | +|----------------------------------------|-------------|-------------|-----------|-----------|---------------------| +| Hexadecimal Value | 43 | 4D | 01 | 01 | 00 0E | +| Transmission order (first bit on left) | 1100 0010 | 1011 0010 | 1000 0000 | 1000 0000 | 0000 0000 0111 0000 | + + + +| Field | Payload | | | | | | | | | | | | | | +|----------------------------------------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------| +| | Time | | | | | | R | F | cUTCO | | R | | | | +| Hexadecimal Value | 00 | 00 | 59 | 09 | DF | B8 | 00 | 06 | 16 | 0F | 00 | 00 | 00 | 00 | +| Transmission order (first bit on left) | 0000 0000 | 0000 0000 | 1001 1010 | 1001 0000 | 1111 1011 | 0001 1101 | 0000 0000 | 0110 0000 | 0110 1000 | 1111 0000 | 0000 0000 | 0000 0000 | 0000 0000 | 0000 0000 | + + + +| Field | FCS | +|----------------------------------------|-----------| +| Hexadecimal Value | 25 | +| Transmission order (first bit on left) | 1010 0100 | + +Figure A.3 – Example time of day message + +##### A.1.3.3 Message contents + +There are three message types defined for the serial communication channel of the 1PPS V.11 interface: + +- **time event message** – timestamp and basic traceability information: +This message is typically transmitted by all clock types using this interface; +- **time announce message** – virtual PTP announce message: +This message is typically transmitted by a PTP clock; +- **GNSS status message** – provides information about the status of a GNSS timing receiver: +This message is typically transmitted by a GNSS-based clock. + +###### A.1.3.3.1 Time event message + +This message is used to output the time of day across the 1PPS V.11 interface. + +Table A.2 – Time event message + +| | | | | | | | | +|-----------------|------------------------|-------------|-------|------|--------|---------------|--------------------| +| Name | Time event message | | | | | | | +| Description | Time event information | | | | | | | +| Type | Reported every second | | | | | | | +| Frame structure | Sync Char 1 | Sync Char 2 | Class | ID | Length | Payload | FCS | +| | 0x43 | 0x4D | 0x01 | 0x01 | 0x000E | See Table A.3 | See clause A.1.3.2 | + +**Table A.3 – Time event message payload** + +| Offset | Length (octets) | Name | Notes | +|--------|-----------------|------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | 6 | Time | PTP seconds (unsigned 48-bit integer) | +| 6 | 1 | Reserved | Reserved | +| 7 | 1 | Flags | Bit 0: leap61 – Positive Leap Second pending
Bit 1: leap59 – Negative Leap Second pending
Bit 2: UTC offset valid
Bit 3: Reserved
Bit 4: timeTraceable – time traceable to a primary time standard
Bit 5: frequencyTraceable – frequency traceable to a primary frequency standard
Bits 6, 7: Reserved | +| 8 | 2 | currentUTCOffset | Current value of the offset between TAI and UTC (i.e., TAI – UTC) | +| 10 | 4 | Reserved | Reserved | + +###### **A.1.3.3.2 Time announce message** + +This message is used to output the quality and traceability of the time delivered across the 1PPS V.11 interface of equipment containing a PTP clock. + +Use of this message on an output interface of a PRTC is for further study, unless the equipment containing a PRTC also contains a T-GM. + +The fields of this message are direct copies of the equivalent named fields of the PTP announce message, as described in [IEEE 1588]. A PTP clock receiving the time of day (ToD) information may treat this information as having been received on a virtual PTP port according to the relevant PTP profile (e.g., [ITU-T G.8275.1]). + +**Table A.4 – Time announce message** + +| | | | | | | | | +|-----------------|----------------------------------------------------------------------------------------------------------------------------------|-------------|-------|------|--------|---------------|--------------------| +| Name | Time announce message | | | | | | | +| Description | Provides information on the quality and traceability of the time source, equivalent to that contained in a PTP announce message. | | | | | | | +| Type | Reported every second | | | | | | | +| Frame structure | Sync Char 1 | Sync Char 2 | Class | ID | Length | Payload | FCS | +| | 0x43 | 0x4D | 0x01 | 0x02 | 0x0020 | See Table A.5 | See clause A.1.3.2 | + +**Table A.5 – Time announce message payload** + +| Offset | Length (octets) | Name | Notes | +|--------|-----------------|-------------------------------------------------|------------------------------------------------------------| +| 0 | 1 | versionPTP | PTP version number | +| 1 | 1 | domainNumber | PTP domain number | +| 2 | 2 | flagField | PTP flag field (see Note) | +| 4 | 8 | sourcePortIdentity.clockIdentity | clockIdentity of the sending clock | +| 12 | 2 | sourcePortIdentity.portNumber | Port number of the sending virtual PTP port | +| 14 | 1 | grandmasterPriority1 | Priority1 value of the PTP Grandmaster | +| 15 | 1 | grandmasterPriority2 | Priority2 value of the PTP Grandmaster | +| 16 | 1 | grandmasterClockQuality.clockClass | clockClass of the PTP Grandmaster | +| 17 | 1 | grandmasterClockQuality.clockAccuracy | clockAccuracy of the PTP Grandmaster | +| 18 | 2 | grandmasterClockQuality.offsetScaledLogVariance | offsetScaledLogVariance of the PTP Grandmaster | +| 20 | 8 | grandmasterClockIdentity | clockIdentity of the PTP Grandmaster | +| 28 | 2 | stepsRemoved | StepsRemoved from the PTP Grandmaster | +| 30 | 1 | timeSource | Type of the source of time provided by the PTP Grandmaster | +| 31 | 1 | Reserved | Reserved | + +NOTE – This is copied directly from the flagfield in the header portion of the PTP announce message, even though some of the flags are not relevant. + +###### A.1.3.3.3 GNSS status message + +This message is used to output the status or alarms of GNSS receivers across the 1PPS V.11 interface of a PRTC. It is not normally produced by a PTP clock, unless they are contained within the same equipment as a GNSS timing receiver. + +**Table A.6 – GNSS status message** + +| | | | | | | | | +|-----------------|----------------------------------------|-------------|-------|------|--------|---------------|--------------------| +| Name | GNSS status message | | | | | | | +| Description | Current status of GNSS timing receiver | | | | | | | +| Type | Reported every second | | | | | | | +| Frame structure | Sync Char 1 | Sync Char 2 | Class | ID | Length | Payload | FCS | +| | 0x43 | 0x4D | 0x01 | 0x03 | 0x0008 | See Table A.7 | See clause A.1.3.2 | + +**Table A.7 – GNSS status message payload** + +| Offset | Length (octets) | Name | Notes | +|--------|-----------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | 1 | Types of time source | 0x00: Beidou (Compass)
0x01: GPS
0x02: PTP
0x03: Galileo
0x04: Glonass
0x05: QZSS
0x06: IRNSS
0x07: GNSS (Combination of constellations)
0x08: Unknown (in case there is no information about which GNSS timescale is really used and no possible action to compel the module to work with a specific GNSS timescale)
0x09 ~ 0xFF: Reserved | +| 1 | 1 | Status of time source | GNSS Fix Type:
0x00: Position unknown
0x01: dead reckoning only (see Note 1)
0x02: 2D-fix
0x03: 3D-fix
0x04: GNSS + dead reckoning combined
0x05: Time only fix
0x06: A-GNSS
0x07: GNSS + SBAS
0x08: GNSS + GBAS
0x09 ~ 0xFF: reserved | +| 2 | 2 | Alarm Status Monitor | Time source alarm status:
Bit 0: Reserved
Bit 1: Antenna open
Bit 2: Antenna shorted
Bit 3: Not tracking satellites
Bit 4: Reserved
Bit 5: Survey-in progress
Bit 6: no stored position
Bit 7: Leap second pending
Bit 8: In test mode
Bit 9: GNSS solution (i.e., derived position and time) is uncertain (see Note 2)
Bit 10: Reserved
Bit 11: Almanac not complete
Bit 12: PPS was generated
Bit 13 ~ Bit 15: Reserved | +| 4 | 4 | Reserved | Reserved | + +NOTE 1 – Dead Reckoning Only – Position from GNSS is lost. Current position is estimated from the last-known position, plus knowledge of the velocity and acceleration of the antenna since the GNSS-based position was known. + +NOTE 2 – GNSS solution is uncertain. When this bit is 1, it indicates that the accuracy of the position derived from GNSS is uncertain, possibly due to not being able to see enough satellites. This alarm may indicate that the antenna has been moved or fallen from place since the unit completed the last self-survey. + +### A.2 1PPS 50 $\Omega$ phase synchronization measurement interface + +The 1PPS interface consists of an unbalanced 50-ohm 1PPS signal that can be used to connect to measurement equipment (see Figure A.4). + +The physical characteristics of this interface are defined in [ITU-T G.703]. + +![Diagram of the unbalanced 1PPS 50 Ω measurement interface showing a driver, connector, cable, and receiver.](58f4167687de8d7339594e5f6fbe0bc6_img.jpg) + +The diagram illustrates the signal flow for an unbalanced 1PPS 50 $\Omega$ measurement interface. On the left, a signal labeled 'PPS\_OUT' enters a yellow 'DRIVER' block, which is connected to ground. The driver's output goes into a blue 'CONN' (connector) block. A red circle at the output of this connector identifies the 'Performance measurement point'. A green 'CABLE' with a break symbol in the middle connects this first connector to a second blue 'CONN' block. Below the cable, a dashed double-headed arrow indicates 'Cable length L'. The second connector feeds into a yellow 'RECEIVER' block, which contains a '50 ohm load' and is also connected to ground. The final output signal is labeled 'PPS\_IN'. The diagram is identified by the code 'G.8271-Y.1366(20)\_FA.4' in the bottom right corner. + +Diagram of the unbalanced 1PPS 50 Ω measurement interface showing a driver, connector, cable, and receiver. + +**Figure A.4 – Unbalanced 1PPS 50 $\Omega$ measurement interface** + +The system must compensate for the internal delays in the system to ensure that the 1PPS signal timing is met at the edge of the box. + +The measurement equipment is expected to compensate for the delays associated with the interconnection of the 1PPS interface. + +## Appendix I + +## Time and phase noise sources in time distribution chains + +(This appendix does not form an integral part of this Recommendation.) + +Quantifying the sources of errors in the time distribution chain is essential in the process to defining noise budget in the network reference model. + +The sources of errors listed in this appendix are based on a network with full timing support provided by telecom boundary clocks (T-BCs). + +In the case of no timing support in some of the nodes, (or in all the nodes), additional sources of noise should be considered. This is for further study. + +The sources of noise due to timing support provided by telecom transparent clocks (T-TCs) are also for further study. + +### I.1 Noise introduced by a primary reference time clock (PRTC) + +Table I.1 provides the sources of errors in a PRTC. + +**Table I.1 – Source of errors in a primary reference time clock** + +| | Source of error | Explanation/Assumptions | +|---|----------------------|-------------------------| +| 1 | Reference time error | See clause I.7.1 | + +### I.2 Noise introduced by a packet master clock function + +Table I.2 provides the sources of errors in a packet master clock function. The packet master clock function may be a part of a T-GM or a T-BC. + +**Table I.2 – Source of errors in a packet master clock function** + +| | Source of error | Explanation/Assumptions | +|---|-----------------------------------------------------------------------|-------------------------| +| 1 | Physical layer protocol (PHY) latency asymmetry internal to the nodes | See clause I.7.2 | + +### I.3 Noise introduced by a packet slave clock function + +Table I.3 provides the sources of errors in a packet slave clock function. The packet slave clock function may be part of a T-TSC or a T-BC. + +**Table I.3 – Source of errors in a packet slave clock function** + +| | Source of error | Explanation/Assumptions | +|---|---------------------------------------------|-------------------------| +| 1 | Local oscillator phase noise | See clause I.7.4 | +| 2 | PHY latency asymmetry internal to the nodes | See clause I.7.2 | +| 3 | Timestamping granularity | See clause I.7.3 | +| 4 | Frequency reference phase error | See clause I.7.5 | +| 5 | Time transients | See clause I.7.6 | + +### I.4 Noise introduced by a telecom transparent clock + +The sources of error in a telecom transparent clock are for further study. + +### I.5 Noise introduced by a link + +Table I.4 provides the sources of errors in a link. + +**Table I.4 – Source of errors in a link** + +| | Source of error | Explanation/Assumptions | +|---|-----------------|-------------------------| +| 1 | Link asymmetry | See clause I.7.7 | + +### I.6 Derivation of delay asymmetry + +Figure I.1 illustrates the delays between a packet slave clock function, or requestor (denoted as slave throughout this clause), and a packet master clock function, or responder (denoted as master throughout this clause). The mean propagation delay is measured at the slave after exchange of event messages. If the Delay Request and the Delay Response mechanism is used (see [IEEE 1588]), the slave sends Delay\_Req and the master sends Delay\_Resp and, separately, Sync and Follow\_Up (i.e., the sending of Sync and Follow\_Up are not part of the Delay\_Req/Delay\_Resp exchange; the Follow\_Up message is sent if, and only if, the clock is two-step). If the Peer Delay mechanism is used (see [IEEE 1588]), the slave sends Pdelay\_Req and the master sends Pdelay\_Resp and, if the clock is two-step, Pdelay\_Resp\_Follow\_Up. + +The figure shows the effective points in the protocol stack of each clock where timestamps are generated, after any corrections for ingress and egress latencies are made (see clause 7.3.4 and Figure 19 of [IEEE 1588]). These points would ideally be at the reference plane, i.e., the boundary point between the PHY and the network physical medium. However, in practice, the corrections for ingress and egress latencies are not perfect, and the effective points at which the timestamps are generated differ from the reference plane. The delays between the effective points where timestamps are taken and the reference plane are denoted $d_{tx}^{PHY,M}$ and $d_{rx}^{PHY,M}$ for egress and ingress, respectively, at the master, and $d_{tx}^{PHY,S}$ and $d_{rx}^{PHY,S}$ for egress and ingress, respectively, at the slave. In this notation, the subscript $t$ (transmit) is used for egress and the subscript $r$ (receive) is used for ingress. In general, these four quantities can all be different. + +The figure also shows the link delays, which are measured from the reference plane of one clock to the reference plane of the other clock. The delay from the master to the slave is denoted $d_{ms}^{link}$ , and the delay from the slave to the master is denoted $d_{sm}^{link}$ . + +![Diagram illustrating delays between a packet master clock function (responder) and a packet slave clock function (requestor). The diagram shows two protocol stacks, each with MAC and PHY layers. A 'Reference plane' is indicated by a dashed line. Delays are labeled as d_rx^PHY,M, d_tx^PHY,M, d_ms^link, d_sm^link, d_rx^PHY,S, and d_tx^PHY,S. Text labels indicate the 'Effective point in protocol stack for ingress/egress timestamp, after any correction for ingress/egress latency' for both master and slave. The diagram is labeled G.8271-Y.1366(12)-Amd.2(15)_Fl.1.](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg) + +Diagram illustrating delays between a packet master clock function (responder) and a packet slave clock function (requestor). The diagram shows two protocol stacks, each with MAC and PHY layers. A 'Reference plane' is indicated by a dashed line. Delays are labeled as d\_rx^PHY,M, d\_tx^PHY,M, d\_ms^link, d\_sm^link, d\_rx^PHY,S, and d\_tx^PHY,S. Text labels indicate the 'Effective point in protocol stack for ingress/egress timestamp, after any correction for ingress/egress latency' for both master and slave. The diagram is labeled G.8271-Y.1366(12)-Amd.2(15)\_Fl.1. + +**Figure I.1 – Illustration of delays between a packet slave clock function, or requestor, and a packet master clock function, or responder** + +The total delay from the master to the slave, $t_{ms}$ , is the sum of the delays in that direction: + +$$t_{ms} = d_{tx}^{PHY,M} + d_{ms}^{link} + d_{rx}^{PHY,S} \quad (I-1)$$ + +Similarly, the total delay from the slave to the master, $t_{sm}$ , is the sum of the delays in that direction: + +$$t_{sm} = d_{tx}^{PHY,S} + d_{sm}^{link} + d_{rx}^{PHY,M} \quad (I-2)$$ + +For the sign convention for the delay asymmetry, the same convention as in clause 7.4.2 of [IEEE 1588] is adopted. Let $D_{mean}$ denote the measured mean path delay (i.e., the measured result of the exchange of Delay\_Req and Delay\_Resp or of Peer Delay messages), and $D_{asym}$ denote the total delay asymmetry. Then, $D_{asym}$ is defined to be positive when the delay from the master to the slave is larger than the delay from the slave to the master. Likewise, $D_{asym}$ is defined to be negative when the delay from the master to the slave is smaller than the delay from the slave to the master. Then: + +$$\begin{aligned} t_{ms} &= D_{mean} + D_{asym} \\ t_{sm} &= D_{mean} - D_{asym} \end{aligned} \quad (I-3)$$ + +Equations (I-3) imply that: + +$$D_{mean} = \frac{t_{ms} + t_{sm}}{2} \quad (I-4)$$ + +as required. Substituting equations (I-1) and (I-2) into equation (I-4) gives: + +$$D_{mean} = \frac{(d_{tx}^{PHY,M} + d_{ms}^{link} + d_{rx}^{PHY,S}) + (d_{tx}^{PHY,S} + d_{sm}^{link} + d_{rx}^{PHY,M})}{2} \quad (I-5)$$ + +Either of the two equations (I-3) may be used with equation (I-4) to obtain the delay asymmetry in terms of the component delays. Using the first of equations (I-3) produces: + +$$\begin{aligned} +D_{asym} &= t_{ms} - D_{mean} \\ +&= (d_{tx}^{PHY,M} + d_{ms}^{link} + d_{rx}^{PHY,S}) - \frac{(d_{tx}^{PHY,M} + d_{ms}^{link} + d_{rx}^{PHY,S}) + (d_{tx}^{PHY,S} + d_{sm}^{link} + d_{rx}^{PHY,M})}{2} \\ +&= \frac{d_{tx}^{PHY,M} - d_{rx}^{PHY,M}}{2} + \frac{d_{ms}^{link} - d_{sm}^{link}}{2} + \frac{d_{rx}^{PHY,S} - d_{tx}^{PHY,S}}{2} \\ +&= e_{phy}^M + e_{link-asym} - e_{phy}^S +\end{aligned} \tag{I-6}$$ + +where: + +$$e_{phy}^M = \frac{d_{tx}^{PHY,M} - d_{rx}^{PHY,M}}{2} \tag{I-7}$$ + +$$e_{link-asym} = \frac{d_{ms}^{link} - d_{sm}^{link}}{2} \tag{I-8}$$ + +$$e_{phy}^S = \frac{d_{tx}^{PHY,S} - d_{rx}^{PHY,S}}{2} \tag{I-9}$$ + +Equations (I-7) and (I-9) are the errors due to PHY latency asymmetry at the master and slave respectively. Equation (I-8) is the error due to link asymmetry. Equation (I-6) indicates that, in computing the total asymmetry, the errors due to PHY latency at the master and due to the link are added, while the error due to PHY latency at the slave is subtracted. + +### I.7 Characteristics of the noise sources + +Each of the sources of noise identified in previous clauses has different characteristics in terms of modelling and accumulation. As an example, the noise due to cascaded T-BC could be analysed according to the traditional approach followed in ITU-T for a chain of clocks. + +The following clauses analyse the noise sources listed in the table above. + +#### I.7.1 Reference time error + +The packet master clock function of the T-GM receives a reference time to distribute. The error can be attributed to: + +GNSS time error. Distribution schemes that use different GNSS systems (e.g., both GPS and future Galileo) might have an inherent time error due to the difference between the atomic clock ensembles that drive the systems. + +GNSS implementation limitations. A GNSS receiver may produce a time signal that has an offset from another GNSS receiver that uses the same satellite system. + +This noise source is applicable to PRTC only. + +The way the noise source, $e_{ref}$ , is modelled is for further study. + +#### I.7.2 PHY latency variation and asymmetry + +This noise source is related to the hardware timestamping function, i.e., to the difference between the timestamp measurement point and the interface to the medium (e.g., [IEEE 802.3] defines the minimum and maximum transmit and receive values possible for each PHY supporting + +[IEEE 802.3]). For a proper implementation, this will typically be in the range of nanoseconds. The PHY latency asymmetry is defined as $(d_{tx}-d_{rx})/2$ , where $d_{tx}$ is the delay on the transmit path and $d_{rx}$ is the delay on the receive path, as indicated in clause I.6 and Figure I.1. + +The delays ( $d_{tx}$ , $d_{rx}$ ) discussed here can be further divided into static delays, which may change based on triggers such as link status reset and power reset, and dynamic delays, which may vary from packet to packet based on triggers such as varying traffic. Depending on the characteristics of any particular delay component, it may or may not be possible to measure and compensate for it. Further detail about the different types of delays involved and their impact on PTP performance of a system is for further study. + +This noise source is applicable to the packet master clock function (in a T-GM or a T-BC) and packet slave clock function (in a T-BC or in a T-TSC). + +The way the noise source, $e_{phy}$ , is modelled is for further study. + +#### I.7.3 Timestamping granularity + +The timestamping granularity depends on the rate of the timestamping clock. The timestamping granularity error is limited in extent by $T_{ts,rX}$ , the increment in the timestamp counter at the receiver: + +$$0 \leq e_{ts} < T_{ts,rX} \quad (\text{I-10})$$ + +If the timestamping clock rate at the receiver is an integer multiple/submultiple of the rate at the sender then the beating effect may be observed and the error $e_{ts}$ is almost static and cannot be reduced by the low-pass filtering inherent in phase-locked loops. If the rates are relatively prime then the error $e_{ts}$ is randomized and is well modelled as white noise (flat spectrum). + +This noise source is applicable to time-of-arrival measurements at the packet master and packet slave. The same model may apply for the time-of-departure measurements. + +#### I.7.4 Local oscillator phase noise + +The packet slave clock function uses the master timing data as reference to filter out its local reference phase noise, so as to produce a time error as small as possible. The better the local oscillator, the less noise it produces. Not all of the phase noise can be filtered out. + +This noise source is applicable to the packet slave clock function (in a T-BC or in a T-TSC) when the frequency is recovered from the PTP messages (i.e., there is no physical layer frequency synchronization support). + +The way the noise source, $e_{\phi}$ , is modelled is for further study. + +#### I.7.5 Frequency reference phase error + +The packet slave clock function (in a T-BC or in a T-TSC) may use an external frequency reference instead of its local oscillator to help with the recovery of time. The frequency reference will have much better timing characteristics than the local oscillator, but it will not be perfect. + +This noise source is applicable to packet slave clock. + +This noise source, $e_{syncE}$ , is defined by the network limits in clause 9.2 of [ITU-T G.8261]. The way this noise source is modelled is for further study. + +#### I.7.6 Time transients + +Reference switches or short interruptions may cause time transients. Failure in the grandmaster or in a link may produce network rearrangement. During such period, time error can accumulate due to some form of holdover functionality. + +This noise source is applicable to packet slave clock. + +The way the noise source, $e_{transient}$ , is modelled is for further study. + +#### I.7.7 Link asymmetry + +Packet timing protocols (such as the network time protocol and the precision time protocol (PTP)) measure the round-trip delay through a network, i.e., the delay from a server to a client and back (or vice versa). The one-way delay is then estimated using the assumption that the forward delay through a network is the same as the reverse delay. Any difference between the forward and reverse delay, (known as delay asymmetry), creates an error in the estimate of the client clock's offset from the server. + +The use of full timing support (such as T-BC or T-TC in every node) can eliminate delay asymmetry due to packet delay variation (PDV), and different traffic load on the two traffic directions and asymmetry caused by packets taking different routes in each direction (in this case an end-to-end transparent clock however would not solve the issue). However, it is unable to correct delay asymmetry on point-to-point links between network elements. This asymmetry arises because the forward and reverse paths travel down different fibres or copper pairs in the same cable. These fibres or pairs may have different lengths and different electrical or optical characteristics which are sufficient to create delay differences. + +Delay asymmetry created by fibre links can have several nanoseconds per metre of difference in each direction. When used over multiple fibre links, the magnitude of this error can become significant relative to the very tight tolerances required by some of the applications being considered. + +The link asymmetry is defined as $(d_{ms} - d_{sm})/2$ , where $d_{ms}$ is the delay on the path from the master clock or responder to the slave clock or requestor, and $d_{sm}$ is the delay on the path from the slave clock or requestor to the master clock or responder, as indicated in clause I.6 and Figure I.1. + +This noise source is applicable to links. + +The way the noise source, $e_{link-asym}$ , is modelled is for further study. + +#### I.7.8 Error in distributing time inside a node + +This error is due to various internal delays when distributing a time reference from a centralized location in a node (e.g., system card) to other locations in a node (e.g., line card). This error might be attributed, for example, to the length of backplane traces, connectors, and various logic functions. + +NOTE – These delays might be non-negligible and proper design and compensation should be performed. + +This noise source is defined as $e_{intranode}$ , and is for further study. This noise source is applicable to T-GM, T-BC and T-TSC. + +### I.8 Time error accumulation in a chain of clocks + +The total time error can be viewed as the sum of a constant time error component and a dynamic time error component. + +NOTE – It is assumed that frequency offset and drift components are not present; therefore, only random components are included in the dynamic time error. + +These two components have different characteristics in terms of modelling and accumulation. See Appendix IV of [b-ITU-T G.8271.1] for further details. + +# Appendix II + +## Time and phase end application synchronization requirements + +(This appendix does not form an integral part of this Recommendation.) + +The following table summarizes the main requirements applicable at the output of the application (e.g., on the radio interface in the case of wireless application). + +**Table II.1 – Time and phase end-application requirements** + +| Application/
Technology | Accuracy | Specification | +|-------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------| +| CDMA2000 |

±3 µs with respect to CDMA System Time, which uses the GPS timescale (which is traceable and synchronous to UTC except for leap second corrections).

±10 µs with respect to CDMA System Time for a period not less than 8 hours (when the external source of CDMA system time is disconnected).

|

[b-3GPP2 C.S0002]
clause 1.3

[b-3GPP2 C.S0010]
clause 4.2.1.1

| +| TD-SCDMA
(NodeB TDD mode) | 3 µs maximum deviation in frame start times between any pair of cells on the same frequency that have overlapping coverage areas. | [b-3GPP TS 25.123]
clause 7.2 | +| WCDMA-TDD
(NodeB TDD mode) | In TDD mode, to support Intercell Synchronization and Handoff, a common timing reference among NodeB is required, and the relative phase difference of the synchronization signals at the input port of any NodeB in the synchronized area shall not exceed 2.5 µs. | [b-3GPP TS 25.402]
clauses 6.1.2 and 6.1.2.1 | +| W-CDMA
MBSFN | 12.8 µs for MBMS over a single frequency network, where the transmission of NodeB is closely time synchronized to a common reference time. | [b-3GPP TS 25.346]
clauses 7.1A and 7.1B.2.1 | +| LTE MBSFN | The cell phase synchronization accuracy measured at BS antenna connectors shall be better than 5 µs. | [b-3GPP TS 36.133]
clause 7.25.2 | +| W-CDMA
(Home NodeB
TDD mode) | Microsecond level accuracy (no hard requirement listed). | [b-3GPP TR 25.866]
clause 8 | +| WiMAX |

1) The downlink frames transmitted by the serving base station and the Neighbour base station shall be synchronized to a level of at least 1/8 cyclic prefix length (which is equal to 1.428 µs).
At the base station, the transmitted radio frame shall be time-aligned with the 1PPS timing pulse.

2) The base station transmit reference timing shall be time-aligned with the 1PPS pulse with an accuracy of ± 1 µs.

|

[b-IEEE 802.16]
Table 6-160,
clause 8.4.13.4

[b-WMF T23-001]
clause 4.2.2

| +| LTE-TDD
(Wide-Area Base station) |

3 µs for small cell (< 3 km radius).

10 µs for large cell (> 3 km radius).

maximum absolute deviation in frame start timing between any pair of cells on the same frequency that have overlapping coverage areas.

| [b-3GPP TS 36.133]
clause 7.4.2 | + +**Table II.1 – Time and phase end-application requirements** + +| Application/
Technology | Accuracy | Specification | +|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------| +| LTE-TDD
(home-area base station) | 1) 3 µs for small cell (< 500m radius). For large cell (> 500 m radius), $1.33 + T_{propagation}$ µs time difference between base stations, where $T_{propagation}$ is the propagation delay between the Home base station and the cell selected as the network listening synchronization source. In terms of the network listening synchronization source selection, the best accurate synchronization source to GNSS should be selected. If the Home base station obtains synchronization without using network listening, the small cell requirement applies.
2) The requirement is 3.475 µs but in many scenarios a 3 µs sync requirement can be adopted. | [b-3GPP TS 36.133]
clause 7.4.2
[b-3GPP TR 36.922]
clause 6.4.1.2 | +| LTE-TDD to CDMA 1xRTT and HRPD handovers | eNB shall be synchronized to GPS time. With external source of CDMA system time disconnected, the eNB shall maintain the timing accuracy within $\pm 10$ µs with respect to CDMA system time for a period of not less than 8 hours. | [b-3GPP TS 36.133]
clause 7.5.2.1 | +| NR TDD | The cell phase synchronization accuracy measured at BS antenna connectors shall be better than 3 µs. | [b-3GPP TS 38.133]
clause 7.4.2 | +| IP network delay monitoring | The requirement depends on the level of quality that shall be monitored. As an example $\pm 100$ µs with respect to a common time reference (e.g., UTC) may be required. $\pm 1$ ms has also been mentioned. | No standard requirement is currently defined. Requirements are operator dependent (depending on the application). | +| Billing and alarms | $\pm 100$ ms with respect to a common time reference (e.g., UTC). | | + +NOTE 1 – In the case of mobile applications, the requirements are generally expressed in terms of phase error between base stations. In the case of a centralized master, the requirement could be expressed as $\pm$ half of the accuracy requirement applicable to the specific technology. +NOTE 2 – The requirements are generally valid during normal conditions. The applicable requirements during failure conditions are for further study. + +**Table II.2 – Other time and phase requirements** + +| Typical applications
(for information) | Synchronization requirements
(MRTD or TAE)
(Note 1) | Specification | +|------------------------------------------------------------------------------------------------------|-----------------------------------------------------------|-----------------------------------------------| +| LTE asynchronous dual connectivity (Note: applicable only for FDD-FDD inter-band dual connectivity). | No network synchronization requirement (Note 2) | [b-3GPP TS 36.133]
clause 7.15.2 | +| LTE synchronous dual connectivity. | 33 µs MRTD | [b-3GPP TS 36.133]
clauses 7.13 and 7.15.2 | + +**Table II.2 – Other time and phase requirements** + +| Typical applications
(for information) | Synchronization
requirements
(MRTD or TAE)
(Note 1) | Specification | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------|------------------------------------------------| +| Inter-band asynchronous EN-DC (E-UTRAN NR Dual Connectivity) (Note 3) | No network synchronization requirement (Note 2) | [b-3GPP TS 38.133]
clause 7.6.2 | +| Inter-band synchronous EN-DC (E-UTRAN NR Dual Connectivity) (Note 3). | 33 µs MRTD | [b-3GPP TS 38.133]
clause 7.6.2 | +| NR Inter-band carrier aggregation. | 33µs MRTD (FR1)
8 µs MRTD (FR2)
25µs MRTD (FR1-FR2)
(Notes 4) | [b-3GPP TS 38.133]
clause 7.6.4 | +| NR Intra-band synchronous EN dual connectivity (Note: applicable for E-UTRA TDD – NR TDD and E-UTRA FDD – NR FDD). | 3 µs MRTD
(Note 6) | [b-3GPP TS 38.133]
clause 7.6.3 | +| NR Inter-band carrier aggregation; with or without MIMO or TX diversity. | 3 µs TAE | [b-3GPP TS 38.104]
clauses 9.6.3.2, 9.6.3.3 | +| NR Intra-band non-contiguous carrier aggregation, with or without MIMO or TX diversity. | 3 µs TAE (FR1)
260ns TAE (FR2)
(Note 7) | [b-3GPP TS 38.104]
clauses 9.6.3.2, 9.6.3.3 | +| NR Intra-band contiguous carrier aggregation, with or without MIMO or TX diversity. | 260 ns TAE (FR1)
130 ns TAE (FR2)
(Notes 4, 7, 8) | [b-3GPP TS 38.104]
clauses 9.6.3.2, 9.6.3.3 | +| LTE Intra-band non-contiguous carrier aggregation with or without MIMO or TX diversity, and inter-band carrier aggregation with or without MIMO or TX diversity. | 260 ns TAE
(Notes 9, 10) | [b-3GPP TS 36.104]
clause 6.5.3.1 | +| LTE Intra-band contiguous carrier aggregation, with or without MIMO or TX diversity. | 130 ns TAE
(Notes 8, 9) | [b-3GPP TS 36.104]
clause 6.5.3.1 | +| Location-based services using OTDOA. | x ns
(Note 11) | | +| NR MIMO or TX diversity transmissions, at each carrier frequency. | 65 ns TAE
(Notes 5, 8) | [b-3GPP TS 38.104]
clauses 9.6.3.2, 9.6.3.3 | +| LTE MIMO or TX diversity transmissions, at each carrier frequency. | 65 ns TAE
(Notes 5, 8) | [b-3GPP TS 36.104]
clause 6.5.3.1 | + +**Table II.2 – Other time and phase requirements** + +| Typical applications
(for information) | Synchronization
requirements
(MRTD or TAE)
(Note 1) | Specification | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------|---------------| +|

NOTE 1 – The synchronization requirements in the 3GPP specifications are expressed in terms of either maximum received timing difference (MRTD) or time alignment error (TAE):

  • – In case of dual connectivity, MRTD concerns the maximum absolute timing mismatch between subframes which are transmitted by Master eNB/gNB (MeNB/MgNB) and Secondary eNB/gNB (SeNB/SgNB) and are scheduled for the same user equipment (UE). For carrier aggregation, MRTD is between the Primary Cell (PCell) and Secondary Cell (SCell). This means that part of this budget should be allocated to propagation time difference between MeNB/MgNB and SeNB/SgNB (in case of dual connectivity) or between PCell and SCell (in case of carrier aggregation). As an example, a 9 km propagation difference accounts for approximately 30 µs, which leaves 3 µs time error between the eNBs. A 7 km propagation difference accounts for approximately 23 µs, which leaves 10 µs time error between the eNBs. The same is applicable for NR.
  • – TAE is defined in [b-3GPP TS 36.104] and [b-3GPP TS 38.104] as the largest timing difference between any two radio signals at the antenna connectors of the base stations. For further details, refer to the relevant 3GPP specifications. In ITU-T terminology, this is equivalent to the maximum relative time error between the two radio signals.

NOTE 2 – For asynchronous dual connectivity there is no network synchronization requirement implied for the base stations. The MRTD values indicated in the 3GPP specification are tolerance requirements on the UE to accept MRTD of up to half of the corresponding time slot length (e.g., half of 1 ms). This is the maximum possible delay difference, since if it is larger than this, the next time slot would be referenced.

NOTE 3 – For inter-band dual connectivity, it is mandatory for the UE to support the asynchronous mode. For intra-band FDD-FDD dual connectivity, it is optional for the UE to support asynchronous mode.

NOTE 4 – FR1: 410 MHz – 7.125 GHz; FR2: 24.25 – 52.6 GHz.

NOTE 5 – The 65ns TAE requirement for MIMO and TX Diversity is an internal equipment specification, and does not result in a requirement on the transport network.

NOTE 6 – Intra-band synchronous EN-DC is defined for co-located deployments only (therefore no budget related to the propagation time differences is allocated to the MRTD in this case).

NOTE 7 – For NR intra-band carrier aggregation, only co-located deployment is applicable.

NOTE 8 – The requirement assumes co-located deployments (e.g., antennas installed on the same roof).

NOTE 9 – Although phase/time accuracy requirements for CA and CoMP are generic and are not defined for any particular network topology, this level of phase error budget in general could be achieved by antennas that are co-located with or connected to the same base band unit (BBU) or centralized unit/distributed unit (CU/DU) via direct links. The support of some of these synchronization requirements for scenarios where the antennas are neither co-located (e.g., as related to Inter-site carrier aggregation) nor connected via direct links to the same BBU or CU/DU is for further study.

NOTE 10 – For the cases of LTE Intra-band non-contiguous carrier aggregation and inter-band carrier aggregation, MRTD requirements are also provided (30.26 µs, see [b-3GPP 36.133] clauses 7.9.2 and 7.9.3).

NOTE 11 – The synchronization accuracy requirements depends on the applicable location accuracy requirements. As an example, to achieve a location accuracy of 40-60m, a max TER of 200ns is required when using OTDOA with a minimum of three basestations as per [b-3GPP TR 37.857]

| | | + +## Appendix III + +## Asymmetry compensation for use of different wavelengths + +(This appendix does not form an integral part of this Recommendation.) + +The compensation of asymmetry due to the use of different wavelengths is obtained by calculating the group delay applicable to wavelengths used in the forward and in the reverse direction. + +Indicating with $A$ the asymmetry, the following applies: + +$$A = d_f - d_r = L * (n_r - n_f)/c$$ + +Where $L$ is the distance, $c$ is the speed of light, $d_f$ and $d_r$ are the forward and reverse transmission delay, and $n_r$ and $n_f$ are the group refractive indexes applicable at the wavelength used in the forward and reverse direction, respectively. + +The evaluation of the refractive indexes can be done either using known chromatic dispersion data (e.g., from the optical fibre data-sheet) or, in the case that the dispersion is unknown, making a direct delay measurement at three different wavelengths (the refractive index for an arbitrary wavelength can then be derived by quadratic interpolation). + +These data can then be used to derive the group delay of a generic wavelength. In particular, in the case of an ITU-T G.652 compliant fibre, the group delay at the applicable wavelengths can be calculated making use of the Sellmeier equations as described in [b-ITU-T G.652]. + +## Appendix IV + +## Link and network asymmetry compensation + +(This appendix does not form an integral part of this Recommendation.) + +In order to compensate for link delay asymmetry, it might be desirable to have in place some automatic link asymmetry calibration procedure. This could be based on calculating the propagation delays by means of two-way measurements made on the fibres used by the traffic. + +The procedure can be done separately on both fibres (in the fibre used in the forward direction and in the fibre used for the reverse direction) providing the forward propagation delay $d_f$ and the reverse propagation delay $d_r$ . This is shown in Figure IV.1. + +![Diagram of link asymmetry calibration process (performed separately on both fibres).](382a9c9e4816bd229191ab4591424dd8_img.jpg) + +The diagram shows two nodes, Node 1 and Node 2, connected by two fibres. Node 1 contains a Transmitter (Tx) and a Receiver (Rx). Node 2 contains a Receiver (Rx) and a Transmitter (Tx). A double-headed arrow labeled 'Calibration for $d_f$ ' is positioned above the top fibre, which is labeled 'Fibre 1 – forward direction' and has an arrow pointing from Node 1 Tx to Node 2 Rx. Another double-headed arrow labeled 'Calibration for $d_r$ ' is positioned below the bottom fibre, which is labeled 'Fibre 2 – reverse direction' and has an arrow pointing from Node 2 Tx to Node 1 Rx. The text 'G.8271-Y.1366(12)-Amd.2(15)\_FIV.1' is at the bottom right. + +Diagram of link asymmetry calibration process (performed separately on both fibres). + +Figure IV.1 – Link asymmetry calibration process (performed separately on both fibres) + +Alternatively, the round trip measurement could be done in two steps on both fibres by reversing the direction of transmission. This is shown in Figure IV.2. + +![Diagram of link asymmetry calibration process (performed on both fibres at the same time).](d8698aacaeead6dfed9a1e448670a2e4_img.jpg) + +The diagram illustrates a two-step calibration process. In 'Step 1', Node 1 (Tx, Rx) and Node 2 (Rx, Tx) are connected by 'Fibre 1 – forward direction, $d_f$ ' (Tx to Rx) and 'Fibre 2 – reverse direction, $d_r$ ' (Tx to Rx). In 'Step 2', the roles are reversed: Node 1 (Rx, Tx) and Node 2 (Tx, Rx) are connected by 'Fibre 1 – reverse direction' (Rx to Tx) and 'Fibre 2 – forward direction' (Tx to Rx). A large downward arrow on the left points to the text 'Calibration of $d_f, d_r$ '. The text 'G.8271-Y.1366(12)-Amd.2(15)\_FIV.2' is at the bottom right. + +Diagram of link asymmetry calibration process (performed on both fibres at the same time). + +Figure IV.2 – Link asymmetry calibration process (performed on both fibres at the same time) + +NOTE 1 – In the case of the connection between master and slave, as shown in Figure I.1, the following would apply: + +$$d_f = d_{ms}$$ + +$$d_r = d_{sm}$$ + +The link asymmetry calibration mechanism must meet an accuracy objective for $d_f$ and $d_r$ estimations. This limit is for further study. + +NOTE 2 – In the case during the asymmetry calculation procedure where one node enters holdover (e.g., caused by the fibres-swapping if this is required by the procedure), the effect of the frequency holdover needs to be taken into account as it might impact the accuracy of the measurement. + +Several implementations are possible, e.g., based on optical switches or fixed or tunable add drop filters. Depending on the implementation, it may not be required to interrupt the traffic during the calibration process and hence in-service operation might be possible. However, the asymmetry compensation is a process that is only required at start-up or during rearrangements in the network. + +This measurement is applicable for wavelength-division-multiplexing (WDM) systems (including optical transport network (OTN)) and non-WDM systems. In the case of wavelength-division-multiplexing systems, this measurement should also take into account possible delay due to dispersion-compensating fibre (DCF). + +NOTE 3 – In the case of WDM systems, the asymmetry due to the use of different wavelengths in the two directions should also be taken into account. Indeed, the use of different wavelengths on the two fibres, (or in a single fibre in the case of a transmission system using a single fibre), would result in different delays even if the fibres have the same length. Note also that a compensation related to the same aspect would be required if the wavelength used during the link asymmetry calibration process is different from the wavelength used by the traffic. Suitable methodologies to address this point are introduced in Appendix III. + +The difference ( $d_f - d_r$ ) can be used in the evaluation of the delay asymmetry to be used in the time recovering process. In particular the *delayAsymmetry* parameter as defined in clause 7.4 of [IEEE 1588] would be half of that difference. + +NOTE 4 – If a T-BC is implemented in every node, the compensation can be triggered directly by the T-BC, which would know the difference ( $d_f - d_r$ ). If this is not the case, some means have to be provided in order to make the difference ( $d_f - d_r$ ) available at the points in the network where the precision time protocol (PTP) messages are processed. This is for further study. + +NOTE 5 – In the case of a time synchronization carried by PTP, the PTP connection may have asymmetry due to a variety of reasons, including network paths, loading levels or cable lengths. The asymmetry of a PTP connection may be evaluated at a PTP network element, if the network element has access to a second time synchronization source that is not significantly impacted by asymmetry (such as a GNSS receiver, or a time synchronization reference carried via timing protocols such as PTP with proper accuracy) as shown in Figure IV.3. If the asymmetry of the PTP connection is evaluated using such a second time synchronization source, then the offset caused by the asymmetry may be compensated by the network element. The same principle could be applied between network elements in a chain. + +![Figure IV.3 – PTP slave evaluating PTP connection asymmetry. The diagram shows two examples. Example #1 shows a PTP master connected to a packet network, which is connected to a PTP slave via Port 1. The PTP slave is also connected to a GNSS connection without asymmetry via Port 2. The PTP connection path is labeled 'PTP connection path with asymmetry'. Example #2 shows a PTP master connected to a packet network, which is connected to a PTP slave via Port 1. The PTP slave is also connected to a Reference PTP master via Port 2. The PTP connection path is labeled 'PTP connection path with asymmetry'. The Reference PTP master is labeled 'Time synchronization reference carried via timing protocols such as PTP with proper accuracy (e.g., direct fibre connection without asymmetry)'.](9f862801bce82634d3b5a1e0a195a799_img.jpg) + +The diagram illustrates two scenarios for a PTP slave to evaluate connection asymmetry. In 'Example #1', a PTP master is connected to a packet network, which in turn connects to a PTP slave through Port 1. The PTP slave also has a GNSS connection without asymmetry at Port 2. The path from the master to the slave is labeled 'PTP connection path with asymmetry'. In 'Example #2', the PTP master connects to a packet network, which connects to a PTP slave through Port 1. The PTP slave connects to a 'Reference PTP master' at Port 2. This reference source provides a 'Time synchronization reference carried via timing protocols such as PTP with proper accuracy (e.g., direct fibre connection without asymmetry)'. The PTP connection path in this example is also labeled 'PTP connection path with asymmetry'. + +Figure IV.3 – PTP slave evaluating PTP connection asymmetry. The diagram shows two examples. Example #1 shows a PTP master connected to a packet network, which is connected to a PTP slave via Port 1. The PTP slave is also connected to a GNSS connection without asymmetry via Port 2. The PTP connection path is labeled 'PTP connection path with asymmetry'. Example #2 shows a PTP master connected to a packet network, which is connected to a PTP slave via Port 1. The PTP slave is also connected to a Reference PTP master via Port 2. The PTP connection path is labeled 'PTP connection path with asymmetry'. The Reference PTP master is labeled 'Time synchronization reference carried via timing protocols such as PTP with proper accuracy (e.g., direct fibre connection without asymmetry)'. + +G.8271-Y.1366(12)-Amd.2(15)\_FIV.3 + +Figure IV.3 – PTP slave evaluating PTP connection asymmetry + +There are cases when asymmetry is generally static but can change over time due to rare network rearrangements, or the re-start of network nodes. This could happen, for example, in the case of OTN + +networks. In these cases, it has been reported that clients carried over OTN may be impacted by changes in the asymmetry whenever a network node is re-started or there are network rearrangements. These can be considered relatively rare events (e.g., in the order of weeks/months), but with an impact that could be on the order of microseconds. Similar events may happen in packet networks (e.g., re-routing). + +These cases can be referred to as "*semi-static asymmetry*". + +For these cases, assuming the phase change in one of the references is sufficiently large compared with the relevant level of accuracy (see Table 1), and sufficiently fast compared with the relevant clock bandwidth, changes in semi-static asymmetry may be controlled when at least 2 independent timing references are available, with the assumptions that only one at the time is impacted by such changes. This is illustrated in Figure IV.4. + +In this example, it is assumed that the asymmetry from all links is first compensated at the start-up by means of a trusted synchronization reference (e.g., via temporary connection to a GNSS reference, or via availability of the GNSS reference as a regular synchronization input). + +![Diagram titled 'Example #3' illustrating the monitoring of semi-static asymmetry. It shows two 'PTP master' boxes at the top, each connected to a 'PTP network' oval. Both 'PTP network' ovals point to a 'PTP slave' box at the bottom. The 'PTP slave' box contains two blue rectangles labeled 'PTP port 1' and 'PTP port 2'. An arrow labeled 'Trusted synchronization reference (e.g., GNSS)' points to the right side of the 'PTP slave' box. Below the diagram is the text 'G.8271-Y.1366(17)-Amd.1(18)_FIV.4'.](f5deee2f3301ee351c4008283ffafbb3_img.jpg) + +Diagram titled 'Example #3' illustrating the monitoring of semi-static asymmetry. It shows two 'PTP master' boxes at the top, each connected to a 'PTP network' oval. Both 'PTP network' ovals point to a 'PTP slave' box at the bottom. The 'PTP slave' box contains two blue rectangles labeled 'PTP port 1' and 'PTP port 2'. An arrow labeled 'Trusted synchronization reference (e.g., GNSS)' points to the right side of the 'PTP slave' box. Below the diagram is the text 'G.8271-Y.1366(17)-Amd.1(18)\_FIV.4'. + +**Figure IV.4 – Monitoring of semi-static asymmetry** + +The PTP network in this example could be based on full timing support or (assisted) partial timing support. + +Assuming only one reference at the time is impacted by changes of network asymmetry (and that, as mentioned earlier, the phase step is sufficiently large and fast), the second reference (not experiencing significant and sudden changes of the relevant parameters, e.g., meanPathDelay, offsetFromMaster) can be used to correct for changes in asymmetry and/or issue an alarm. This may assume that full exchange of PTP messages is present also on the PTP port which is not in the SLAVE state. + +The correction for asymmetries during normal operation requires proper operation in the slave as to control phase transients, according to the relevant clock specification. + +NOTE 6 – Correction for asymmetry may not be sufficiently accurate after several compensations. Therefore, recalibration with a trusted source would be required. + +NOTE 7 – The PTP slave shown in Figures IV.3 and IV.4 could be implemented in a T-BC (i.e., there could be downstream nodes connected to the node correcting for asymmetries in the network). + +NOTE 8 – The procedures for scheduled or on-demand measurement of asymmetry are for further study. + +# Appendix V + +## Delay asymmetry resulting from interface rate change in PTP-unaware network elements + +(This appendix does not form an integral part of this Recommendation.) + +In case the master and slave are not connected to a PTP aware network element (e.g., boundary clock (BC) or transparent clock (TC)) and are not using the same Ethernet line speed, a delay asymmetry can be generated due to the "store and forwarding" nature of Ethernet switches, meaning the switch needs to receive the entire frame before starting transmission on port with a faster line speed, to ensure that the packet data is available for transmission. The minimal time necessary to transfer the packet across the switch depends on the length of the packet and the ingress line rate. Sync and Delay\_Req PTP packets have been defined to have the same length in order to reduce delay asymmetry caused by different transition delay, however Ethernet speed mismatch will generate asymmetry. + +The expected asymmetry can be estimated based on the PTP event message packet size and interfaces speed. + +In case the static asymmetry caused by the speed mismatch is known, it can be compensated by the slave using asymmetric delay compensation mechanism defined in [IEEE 1588], clause 11.6. + +The following example is used to illustrate the asymmetry generated by a speed mismatch: + +- packet format uses UDP/IPv4/Ethernet header, giving total packet size of 86 bytes (excluding preamble and FCS); +- preamble is 8 bytes; +- FCS is 4 bytes; +- PTP Grand Master timestamp event interface is GE (1000 Mbit/s); +- PTP slave timestamp event interface is FE (100 Mbit/s); +- the packet switched network (PSN) delay is assumed to be symmetrical. + +![Diagram illustrating a speed mismatch example in a network. A Master (IG) sends a 'Sync' message to a Slave (100M) via two Switches (one IG, one 100M). The network is labeled 'Network (PSN)'. The diagram shows buffering delays at the IG and 100M interfaces. The Slave sends a 'Delay request' back to the Master. The diagram is labeled G.8271-Y.1366(16)_FV.1.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +The diagram shows a network topology with a Master connected to an IG (Interface Group) switch, which is connected to a Network (PSN) cloud. The Network (PSN) cloud is connected to another switch (100M) which is connected to a Slave (100M). The Master sends a 'Sync' message to the Slave. The Slave sends a 'Delay request' back to the Master. The diagram shows buffering delays at the IG and 100M interfaces. The diagram is labeled G.8271-Y.1366(16)\_FV.1. + +Diagram illustrating a speed mismatch example in a network. A Master (IG) sends a 'Sync' message to a Slave (100M) via two Switches (one IG, one 100M). The network is labeled 'Network (PSN)'. The diagram shows buffering delays at the IG and 100M interfaces. The Slave sends a 'Delay request' back to the Master. The diagram is labeled G.8271-Y.1366(16)\_FV.1. + +**Figure V.1 – Speed mismatch example** + +This yields the following equation for delay between the timestamp event points. + +In the forward direction from the master to the slave, the delay between the timestamp event points is: + +$$t2 = (L_{PKT} + L_{FCS})_{bytes} \times 8_{bits/byte} \times GE_{ns/bit} + D_{PSN} + (L_{Pre-amble})_{bytes} \times 8_{bits/byte} \times FE_{ns/bit} + t1 \quad (V-1)$$ + +In the reverse direction from the slave to the master, the delay between the timestamp event points is: + +$$t4 = (L_{PKT} + L_{FCS})_{bytes} \times 8_{bits/byte} \times FE_{ns/bit} + D_{PSN} + (L_{Pre-amble})_{bytes} \times 8_{bits/byte} \times GE_{ns/bit} + t3 \quad (V-2)$$ + +The $\langle meanPathDelay \rangle$ formula from equation (V-2) is: + +$$\langle meanPathDelay \rangle = \frac{[(t2 - t1) + (t4 - t3)]}{2} \quad (V-3)$$ + +Substituting $(t2 - t1)$ for equation (V-1) and $(t4 - t3)$ for equation (V-2) then: + +$$\langle meanPathDelay \rangle = \frac{(L_{PKT} + L_{FCS} + L_{Pre-amble}) \times 8 \times (GE + FE)_{ns} + 2 \times D_{PSN}}{2} \quad (V-4)$$ + +$$\langle meanPathDelay \rangle = (L_{PKT} + L_{FCS} + L_{Pre-amble}) \times 8 \times \frac{GE + FE}{2}_{ns} + D_{PSN} \quad (V-5)$$ + +By convention the $\langle delayPathAsymmetry \rangle$ is positive when the forward path is longer than the reverse path. + +The delay path asymmetry is then the difference between equations (V-1) and (V-5). + +$$\langle delayPathAsymmetry \rangle = (L_{PKT} + L_{FCS}) \times 8 \times \left( \frac{GE - FE}{2} \right)_{ns} + (L_{Pre-amble}) \times 8 \times \left( \frac{FE - GE}{2} \right)_{ns} \quad (V-6)$$ + +or as the difference between equations (V-5) and (V-2) + +$$\langle \text{delayPathAsymmetry} \rangle = (L_{\text{PKT}} + L_{\text{FCS}}) \times 8 \times \left( \frac{GE - FE}{2} \right)_{\text{ns}} + (L_{\text{Pre-amble}}) \times 8 \times \left( \frac{FE - GE}{2} \right)_{\text{ns}} \quad (\text{V-7})$$ + +Substituting for real values into equation (V-6) we obtain: + +$$\langle \text{delayPathAsymmetry} \rangle = (86 + 4) \times 8 \times \left( \frac{1 - 10}{2} \right)_{\text{ns}} + (8) \times 8 \times \left( \frac{10 - 1}{2} \right)_{\text{ns}}$$ + +$$\langle \text{delayPathAsymmetry} \rangle = -2952_{\text{ns}}$$ + +The general term for the delay asymmetry caused by the speed mismatch: + +$$\langle \text{delayPathAsymmetry} \rangle = (L_{\text{PKT}} + L_{\text{FCS}}) \times 8 \times \left( \frac{V_{\text{Master}} - V_{\text{Slave}}}{2} \right) + (L_{\text{Pre-amble}}) \times 8 \times \left( \frac{V_{\text{Master}} - V_{\text{Slave}}}{2} \right) \quad (\text{V-8})$$ + +Where: + +$L_{\text{PKT}}$ is the length of the packet (excluding the preamble and FCS) in bytes + +$L_{\text{FCS}}$ is the length of the packet FCS in bytes + +$L_{\text{Pre-amble}}$ is the length of the packet preamble in bytes + +$V_{\text{Master}}$ is the timestamp interface bit period on the PTP Master Clock in seconds/bit + +$V_{\text{Slave}}$ is the timestamp interface bit period on the PTP Slave Clock in seconds/bit + +# Appendix VI + +## Time synchronization aspects in TDD based mobile communication systems + +(This appendix does not form an integral part of this Recommendation.) + +In TDD-based mobile communication systems (hereafter, TDD systems), uplink (UL) signals which are transmitted from user equipment (UE) to base stations (BS), and downlink (DL) signals which are transmitted in the opposite direction, are multiplexed along the time axis alternately on a common frequency channel. Interference in TDD systems occur when signals from adjacent cells overlap a UL time slot at a base station or DL time slot at a UE. + +Synchronization errors at a single base station can lead to performance degradation of neighbouring base stations, whether the base stations are of the same operator or different operators. This is due to the interference caused by the neighbouring base station. Hence, in TDD systems, it is essential that base stations receive accurate synchronization. + +The frequency allocation for TDD systems operated by multiple mobile operators usually includes guard frequency bands between frequency bands assigned to different operators to avoid interferences resulting from spurious noises as shown in Figure VI.1. If TDD systems are operated without guard frequency bands, not only intra-operator time synchronization but also inter-operator time synchronization to a common timing standard is required. One possibility is to make it explicit that the reference must be traceable to a specific common recognized time standard source. Co-ordinated Universal Time (UTC) might be a good candidate. In fact, as per Recommendation [b-ITU-R TF.460] all standard-frequency and time-signal emissions should conform to UTC. Further information is provided in [b-3GPP TS 38.401]. + +NOTE – Given the 3GPP requirement for a continuous timescale, the actual implementation in this case could make use of the content of the distributed UTC information that is not impacted by leap seconds, e.g., GPS time in case the reference is carried by a GPS signal. + +It should be mentioned that in addition to having synchronization references traceable to a common recognized time standard source, adopting common TDD signal frame patterns is also required. + +![Figure VI.1: Examples of frequency allocation for TDD systems with and without guard frequency bands. The figure shows two scenarios: 'With guard frequency bands' and 'Without guard frequency bands'. In the 'With guard frequency bands' scenario, three operators (A, B, and C) are shown with sub-bands of 80 MHz each, separated by guard bands (GB) of 20 MHz. The total frequency range is from 3400 MHz to 3700 MHz. In the 'Without guard frequency bands' scenario, the same three operators are shown with sub-bands of 100 MHz each, with no guard bands (GB = 0 MHz) between them. The total frequency range is also from 3400 MHz to 3700 MHz.](0cda1f4c603972dc23aefc2cc3cbd135_img.jpg) + +With guard frequency bands + +Operator A sub-band 1 80 MHz + +Operator B sub-band 2 80 MHz + +Operator C sub-band 3 80 MHz + +3400 MHz GB > 20 MHz GB > 20 MHz 3700 MHz + +Without guard frequency bands + +Operator A sub-band 1 100 MHz + +Operator B sub-band 2 100 MHz + +Operator C sub-band 3 100 MHz + +3400 MHz GB = 0 MHz GB = 0 MHz 3700 MHz + +G.8271-Y.1366(20)\_FVI.1 + +Figure VI.1: Examples of frequency allocation for TDD systems with and without guard frequency bands. The figure shows two scenarios: 'With guard frequency bands' and 'Without guard frequency bands'. In the 'With guard frequency bands' scenario, three operators (A, B, and C) are shown with sub-bands of 80 MHz each, separated by guard bands (GB) of 20 MHz. The total frequency range is from 3400 MHz to 3700 MHz. In the 'Without guard frequency bands' scenario, the same three operators are shown with sub-bands of 100 MHz each, with no guard bands (GB = 0 MHz) between them. The total frequency range is also from 3400 MHz to 3700 MHz. + +Figure VI.1 – Examples of frequency allocation for TDD systems with and without guard frequency bands + +### VI.1 An overview of radio-interference in TDD systems + +As shown in Figure VI.2, TDD systems have two types of interference conditions: BS-to-BS and UE-to-UE. Interferences occur in TDD systems due to propagation delay of signals in each scenario described below. The propagation delay of a DL signal is higher in large cells than in small cells. + +Moreover, the propagation delay of a DL signal is not proportional to the cell radius in inter-operator interference, unlike in intra-operator interferences as shown in Figure VI.3. Thus, in addition to the relative time error between cells, there are other aspects that should be considered regarding the occurrence of interferences in TDD systems. + +![Figure VI.2: Overview of interference patterns in TDD systems. The diagram shows two overlapping cells, Cell A and Cell B. Each cell contains a Base Station (BS) and User Equipment (UE). Signal power is plotted against time (t) for Downlink (DL) and Uplink (UL) transmissions, with a Guard Period (GP) between them. Time errors are indicated for both cells. Propagation delays are shown as dashed lines between BS A and BS B, and between UE A and UE B. BS-to-BS interference and UE-to-UE interference are indicated by double-headed arrows between the respective components in the two cells. The diagram is labeled G.8271-Y.1366(20)_FVI.2.](878d9539700bd792e7d12ad6f1203c5d_img.jpg) + +Figure VI.2: Overview of interference patterns in TDD systems. The diagram shows two overlapping cells, Cell A and Cell B. Each cell contains a Base Station (BS) and User Equipment (UE). Signal power is plotted against time (t) for Downlink (DL) and Uplink (UL) transmissions, with a Guard Period (GP) between them. Time errors are indicated for both cells. Propagation delays are shown as dashed lines between BS A and BS B, and between UE A and UE B. BS-to-BS interference and UE-to-UE interference are indicated by double-headed arrows between the respective components in the two cells. The diagram is labeled G.8271-Y.1366(20)\_FVI.2. + +**Figure VI.2 – Overview of interference patterns in TDD systems** + +![Figure VI.3: Relationship between intra- and inter-operator interference. The diagram shows two overlapping cells, Operator A Cell and Operator B Cell. Each cell contains two Base Stations (BS). Intra-operator interference is shown as a dashed double-headed arrow between the two BSs within Operator A Cell. Inter-operator interference is shown as a solid double-headed arrow between a BS in Operator A Cell and a BS in Operator B Cell. The diagram is labeled G.8271-Y.1366(20)_FVI.3.](8e80de0cac529b2c3775d677c5203133_img.jpg) + +Figure VI.3: Relationship between intra- and inter-operator interference. The diagram shows two overlapping cells, Operator A Cell and Operator B Cell. Each cell contains two Base Stations (BS). Intra-operator interference is shown as a dashed double-headed arrow between the two BSs within Operator A Cell. Inter-operator interference is shown as a solid double-headed arrow between a BS in Operator A Cell and a BS in Operator B Cell. The diagram is labeled G.8271-Y.1366(20)\_FVI.3. + +**Figure VI.3 – Relationship between intra- and inter-operator interference** + +### VI.2 Signal frame format of TDD systems + +Guard periods (GPs) in the signal frame format of TDD systems are provided at the switching point around DL-to-UL and UL-to-DL switching as shown in Figure VI.4. Guard periods are not used for signal transmission but contribute to reducing interference during DL to UL switching. $T_{DL\_UL}$ is + +defined to allow sufficient time for the BTS and UE transceivers to switch between sending and receiving. The guard period allocated for UL to DL switching is guaranteed by the $TA_{offset}$ , which is added to the RF air delay-dependent timing advance (see [b-3GPP TS 38.211] and [b-3GPP TS 38.133]) for controlling the transmission timing of the UL radio frames. + +![Figure VI.4: Signal frame format of TDD systems. The diagram shows a sequence of five blocks: DL, GP, UL, GP, DL. Above the first GP, an arrow labeled T_DL_UL points from the DL/GP boundary to the GP/UL boundary. Above the second GP, an arrow labeled TA_offset points from the UL/GP boundary to the GP/DL boundary. The text G.8271-Y.1366(20)_FVI.4 is at the bottom right.](6cc85a2b62fd8a2a3faab29730f20e81_img.jpg) + +Figure VI.4: Signal frame format of TDD systems. The diagram shows a sequence of five blocks: DL, GP, UL, GP, DL. Above the first GP, an arrow labeled T\_DL\_UL points from the DL/GP boundary to the GP/UL boundary. Above the second GP, an arrow labeled TA\_offset points from the UL/GP boundary to the GP/DL boundary. The text G.8271-Y.1366(20)\_FVI.4 is at the bottom right. + +Figure VI.4 – Signal frame format of TDD systems + +### VI.3 Base station to base station interference + +#### VI.3.1 Downlink to uplink switching point + +The time synchronization error between base stations ( $T_{Sync}$ ) is defined as the timing error at the Antenna Reference Point (ARP). If the propagation time between interfering and interfered base stations is represented as $T_{prop\_BS2BS}$ , and power ramp-down time at the base station transmitter as $T_{bts\_rampdown}$ , BS-to-BS interference at DL-to-UL switching occurs under the following condition (see Figure VI.5): + +$$T_{Sync} > T_{DL\_UL} - T_{prop\_BS2BS} - T_{bts\_rampdown} \quad (VI-1)$$ + +![Figure VI.5: BS to BS interference at DL to UL switching point. The diagram shows two base stations, 'Interfering BS' (top) and 'Interfered BS' (bottom). The Interfering BS has a DL segment followed by a UL segment. The Interfered BS also has a DL segment followed by a UL segment. A dashed line from the DL/UL switching point of the Interfering BS shows a 'Propagation delay' to the DL/UL switching point of the Interfered BS. The time difference between the DL/UL switching point of the Interfered BS and the start of its UL segment is labeled T_DL_UL. The time difference between the DL/UL switching point of the Interfered BS and the start of its DL segment is labeled T_prop_BS2BS. The time difference between the start of the UL segment and the start of the interference (shaded grey) is labeled T_bts_rampdown. The interference is shown as a shaded grey area in the UL segment of the Interfered BS. Above the diagram, the condition T_Sync > T_DL_UL - T_prop_BS2BS - T_bts_rampdown is given. The text G.8271-Y.1366(20)_FVI.5 is at the bottom right.](a93de4c3f80bd4a972ab65510b09b68d_img.jpg) + +Figure VI.5: BS to BS interference at DL to UL switching point. The diagram shows two base stations, 'Interfering BS' (top) and 'Interfered BS' (bottom). The Interfering BS has a DL segment followed by a UL segment. The Interfered BS also has a DL segment followed by a UL segment. A dashed line from the DL/UL switching point of the Interfering BS shows a 'Propagation delay' to the DL/UL switching point of the Interfered BS. The time difference between the DL/UL switching point of the Interfered BS and the start of its UL segment is labeled T\_DL\_UL. The time difference between the DL/UL switching point of the Interfered BS and the start of its DL segment is labeled T\_prop\_BS2BS. The time difference between the start of the UL segment and the start of the interference (shaded grey) is labeled T\_bts\_rampdown. The interference is shown as a shaded grey area in the UL segment of the Interfered BS. Above the diagram, the condition T\_Sync > T\_DL\_UL - T\_prop\_BS2BS - T\_bts\_rampdown is given. The text G.8271-Y.1366(20)\_FVI.5 is at the bottom right. + +Figure VI.5 – BS to BS interference at DL to UL switching point + +Note that the interference decays as the path loss increases with increased $T_{prop\_BS2BS}$ , so that at after certain distance it will not be significant. + +#### VI.3.2 Uplink to downlink switching point + +BS-to-BS interference at the UL-to-DL switching point occurs under the following condition where $T_{bts\_rampup}$ is the power ramp-up time at the base station transmitter (see Figure VI.6): + +$$T_{sync} > TA_{offset} + T_{prop\_BS2BS} - T_{bts\_rampup} \quad (VI-2)$$ + +Propagation delay may take a smaller value in inter-operator interference than in intra-operator interference, so this type of interference may have a greater possibility of occurring. + +![Diagram illustrating BS to BS interference at the UL to DL switching point. It shows three horizontal timelines for 'Interfering BS', an intermediate BS, and 'Interfered BS'. The 'Interfering BS' timeline has UL and DL sections separated by a 'TA_offset'. A 'Propagation delay' arrow points from the UL section of the 'Interfering BS' to the UL section of the intermediate BS. The intermediate BS timeline also has UL and DL sections separated by a 'TA_offset'. A 'T_prop_BS2BS' arrow points from the start of the UL section of the 'Interfering BS' to the start of the UL section of the intermediate BS. A 'T_bts_rampup' arrow points from the start of the DL section of the intermediate BS to the start of the DL section of the 'Interfered BS'. The 'Interfered BS' timeline has UL and DL sections separated by a 'TA_offset'. A shaded gray rectangle in the UL section of the 'Interfered BS' represents the interference. An arrow labeled 'Interference' points from the DL section of the intermediate BS to this shaded rectangle. A 'T_Sync' arrow points from the start of the UL section of the 'Interfered BS' to the start of the shaded interference rectangle. The diagram is labeled 'G.8271-Y.1366(20)_FVI.6'.](c1df61cc3717e878a48e530218403403_img.jpg) + +Diagram illustrating BS to BS interference at the UL to DL switching point. It shows three horizontal timelines for 'Interfering BS', an intermediate BS, and 'Interfered BS'. The 'Interfering BS' timeline has UL and DL sections separated by a 'TA\_offset'. A 'Propagation delay' arrow points from the UL section of the 'Interfering BS' to the UL section of the intermediate BS. The intermediate BS timeline also has UL and DL sections separated by a 'TA\_offset'. A 'T\_prop\_BS2BS' arrow points from the start of the UL section of the 'Interfering BS' to the start of the UL section of the intermediate BS. A 'T\_bts\_rampup' arrow points from the start of the DL section of the intermediate BS to the start of the DL section of the 'Interfered BS'. The 'Interfered BS' timeline has UL and DL sections separated by a 'TA\_offset'. A shaded gray rectangle in the UL section of the 'Interfered BS' represents the interference. An arrow labeled 'Interference' points from the DL section of the intermediate BS to this shaded rectangle. A 'T\_Sync' arrow points from the start of the UL section of the 'Interfered BS' to the start of the shaded interference rectangle. The diagram is labeled 'G.8271-Y.1366(20)\_FVI.6'. + +**Figure VI.6 – BS to BS interference at UL to DL switching point** + +### VI.4 User equipment to user equipment interference + +Reachability of the signal from interfering UE to interfered UE is lower in the case of UE-to-UE interference than in the case of BS-to-BS interference. Thus, only the condition under which both UEs are located close to the cell edge can cause intra-operator interferences. On the other hand, UE-to-UE interference may occur anywhere in the cell in the case of inter-operator interference. Similar relationships can be derived for BS-to-BS interference, where time synchronization error between base stations exceeding a certain threshold would cause interference between the UEs. + +# Appendix VII + +## Time scales + +(This appendix does not form an integral part of this Recommendation.) + +This appendix gives some introductions on time scales and the relationship between them. + +### VII.1 Time scales + +#### Universal Time (UT) + +UT is a time standard based on Earth's rotation. It is a modern continuation of Greenwich Mean Time (GMT), i.e., the mean solar time on the Prime Meridian at Greenwich, England. UT1 is the principal form of UT with the Earth Rotation Angle (ERA) adjustment. + +A mean solar day is 24 mean solar hours, and is 86400 mean solar seconds, which means a UT second is 1/86400 of a mean solar day. + +#### International Atomic Time (TAI) + +In October 1967, the General Conference on Weights and Measures redefined the International System of Units (SI) second to be based on the hyperfine resonance of Cesium. The latest definition of SI second is provided in [b-SI System] published by the International Bureau of Weights and Measures (BIPM). + +International Atomic Time (TAI) is a continuous time scale counted with the SI second, with the latest definition also provided in [b-SI System]. The beginning time or epoch of TAI is 0h 1st Jan. 1958 (UT), which means that TAI was synchronized with UT at the time. The two timescales have drifted apart ever since, due to the irregular rotation of Earth. + +TAI is maintained by the BIPM using data from some 400 atomic clocks in over 80 national laboratories that maintain the best primary Cesium standards. + +#### Coordinated Universal Time (UTC) + +TAI is a uniform metering system, which is very important for measuring time intervals. UT, on the other hand, always reflects the position of Earth in space, and corresponds to the four seasons and day and night. It is a time that is familiar in daily life. To balance these two needs, UTC was introduced. + +UTC time includes two concepts: + +- UTC second is TAI second, i.e., SI second as measured using Cesium atoms; +- UTC day is UT day, i.e., mean solar day as measured by the rotation of the earth. + +UTC is based on TAI with leap seconds added at irregular intervals to compensate for the slowing rotation of Earth. Leap seconds keep UTC within 0.9 second of UT1. The dates of application of the leap second are decided by the International Earth Rotation Service (IERS). + +NOTE – This means that the UT second has a longer duration to the SI second used in the TAI and UTC timescales. + +UTC is also maintained by the BIPM. Physical realizations of UTC, UTC(k), are maintained in national metrology institutes or observatories contributing with their clock data to the BIPM. These time laboratories then use UTC to steer their clock. Values of UTC-UTC(k) at five-day intervals are published in the monthly BIPM *Circular T* [b-Circular-T], which gives official traceability of UTC to its representations UTC(k). + +[b-ITU-R TF.460] recommends that all standard-frequency and time-signal emissions should conform to UTC. + +### **VII.2 Relationship between time scales** + +The atomic time scales TAI and UTC are disseminated monthly through the BIPM *Circular T* [b-Circular-T]. After the leap second on 1st January 2017, the difference between the time scales was 37s. + +## Bibliography + +- [b-ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*. +- [b-ITU-T G.8271.1] Recommendation ITU-T G.8271.1/Y.1366.1 (2020), *Network limits for time synchronization in packet networks*. +- [b-ITU-T G.8271.2] Recommendation ITU-T G.8271.2/Y.1366.2 (2017), *Network limits for time synchronization in packet networks with partial timing support from the network*. +- [b-ITU-R TF.460] Recommendation ITU-R TF.460 (2002), *Standard-frequency and time-signal emissions*. +- [b-IEEE 802.16] IEEE 802.16-2017, *IEEE Standard for Air Interface for Broadband Wireless Access Systems*. +<[https://standards.ieee.org/standard/802\\_16-2017.html](https://standards.ieee.org/standard/802_16-2017.html)> +- [b-WMF T23-001] WMF-T23-001-R015v03 (2012), *WiMAX Forum® Air Interface Specifications – Mobile System Profile Specification – Common Part*. +<[http://wimaxforum.org/sites/wimaxforum.org/files/technical\\_document/2012/04/WMF-T23-001-R015v03\\_MSP-Common-Part.pdf](http://wimaxforum.org/sites/wimaxforum.org/files/technical_document/2012/04/WMF-T23-001-R015v03_MSP-Common-Part.pdf)> +- [b-3GPP TR 25.836] 3GPP TR 25.836 (2001), *Node B synchronization for TDD*. +<> +- [b-3GPP TR 25.866] 3GPP TR 25.866 (2010), *1.28 Mcps TDD Home NodeB (HNB) study item technical report*. +<> +- [b-3GPP TR 36.814] 3GPP TR 36.814 (2017), *Evolved Universal Terrestrial Radio Access 3GPP TS 25.123 (2019) (E-UTRA); Further advancements for E-UTRA physical layer aspects*. +<> +- [b-3GPP TR 36.922] 3GPP TR 36.922 (2018), *Evolved Universal Terrestrial Radio Access (E-UTRA); TDD Home eNode B (HeNB) Radio Frequency (RF) requirements analysis*. +<> +- [b-3GPP TR 37.857] 3GPP TR 37.857 (2016), *Study on indoor positioning enhancements for UTRA and LTE*. +<> +- [b-3GPP TS 25.123] 3GPP TS 25.123 (2019), *Requirements for support of radio resource management (TDD)*. +<> +- [b-3GPP TS 25.346] 3GPP TS 25.346 (2018), *Introduction of the Multimedia Broadcast/Multicast Service (MBMS) in the Radio Access Network (RAN); Stage 2*. +<[https://www.etsi.org/deliver/etsi\\_ts/125300\\_125399/125346/15.00.00\\_60/ts\\_125346v150000p.pdf](https://www.etsi.org/deliver/etsi_ts/125300_125399/125346/15.00.00_60/ts_125346v150000p.pdf)> +- [b-3GPP TS 25.402] 3GPP TS 25.402 (2018), *Universal Mobile Telecommunications Systems (UMTS); Synchronization in UTRAN Stage 2*. +<[https://www.etsi.org/deliver/etsi\\_ts/125400\\_125499/125402/15.00.00\\_60/ts\\_125402v150000p.pdf](https://www.etsi.org/deliver/etsi_ts/125400_125499/125402/15.00.00_60/ts_125402v150000p.pdf)> +- [b-3GPP TS 36.104] 3GPP TS 36.104 (2019), *LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio transmission and reception*. +<[https://www.etsi.org/deliver/etsi\\_ts/136100\\_136199/136104/15.05.00\\_60/ts\\_136104v150500p.pdf](https://www.etsi.org/deliver/etsi_ts/136100_136199/136104/15.05.00_60/ts_136104v150500p.pdf)> + +- [b-3GPP TS 36.133] 3GPP TS 36.133 (2019), *LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for support of radio resource management.* +[https://www.etsi.org/deliver/etsi\\_ts/125400\\_125499/125402/15.00.00\\_60/ts\\_125402v150000p.pdf](https://www.etsi.org/deliver/etsi_ts/125400_125499/125402/15.00.00_60/ts_125402v150000p.pdf) +- [b-3GPP TS 38.104] 3GPP TS 38.104 (2019), *5G; NR; Base Station (BS) radio transmission and reception.* +[https://www.etsi.org/deliver/etsi\\_ts/138100\\_138199/138104/15.05.00\\_60/ts\\_138104v150500p.pdf](https://www.etsi.org/deliver/etsi_ts/138100_138199/138104/15.05.00_60/ts_138104v150500p.pdf) +- [b-3GPP TS 38.133] 3GPP TS 38.133 (2019), *5G; NR; Requirements for support of radio resource management.* +[https://www.etsi.org/deliver/etsi\\_ts/138100\\_138199/138133/15.06.00\\_60/ts\\_138133v150600p.pdf](https://www.etsi.org/deliver/etsi_ts/138100_138199/138133/15.06.00_60/ts_138133v150600p.pdf) +- [b-3GPP TS 38.211] 3GPP TS 38.211 (2019), *5G; NR; Physical channels and modulation.* +[https://www.etsi.org/deliver/etsi\\_ts/138200\\_138299/138211/15.02.00\\_60/ts\\_138211v150200p.pdf](https://www.etsi.org/deliver/etsi_ts/138200_138299/138211/15.02.00_60/ts_138211v150200p.pdf) +- [b-3GPP TS 38.401] 3GPP TS 38.401(2019), *5G; NG-RAN; Architecture description.* +[https://www.etsi.org/deliver/etsi\\_ts/138400\\_138499/138401/15.05.00\\_60/ts\\_138401v150500p.pdf](https://www.etsi.org/deliver/etsi_ts/138400_138499/138401/15.05.00_60/ts_138401v150500p.pdf) +- [b-3GPP2 C.S0002] 3GPP2 C.S0002-F v2.0 (2014), *Physical layer standard for cdma2000 Spread Spectrum Systems.* +[https://www.3gpp2.org/Public\\_html/Specs/C.S0002-D\\_v2.0\\_051006.pdf](https://www.3gpp2.org/Public_html/Specs/C.S0002-D_v2.0_051006.pdf) +- [b-3GPP2 C.S0010] 3GPP2 C.S0010-E v2.0 (2014), *Recommended Minimum Performance Standards for cdma2000 Spread Spectrum Base Stations.* +[http://www.arib.or.jp/english/html/overview/doc/STD-T64v7\\_00/Specification/ARIB\\_STD-T64-C.S0010-Ev2.0.pdf](http://www.arib.or.jp/english/html/overview/doc/STD-T64v7_00/Specification/ARIB_STD-T64-C.S0010-Ev2.0.pdf) +- [b-SI System] BIPM, 9th Edition (2019), *The International System of Units.* + +- [b-Circular-T] BIPM, *Circular -T* (published monthly). + + + + +## ITU-T Y-SERIES RECOMMENDATIONS + +## GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES + +| | | +|--------------------------------------------------------------------|----------------------| +| GLOBAL INFORMATION INFRASTRUCTURE | | +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | +| INTERNET PROTOCOL ASPECTS | | +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | +| IPTV over NGN | Y.1900–Y.1999 | +| NEXT GENERATION NETWORKS | | +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Enhancements to NGN | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Network control architectures and protocols | Y.2500–Y.2599 | +| Packet-based Networks | Y.2600–Y.2699 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | +| Carrier grade open environment | Y.2900–Y.2999 | +| FUTURE NETWORKS | Y.3000–Y.3499 | +| CLOUD COMPUTING | Y.3500–Y.3999 | +| INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES | | +| General | Y.4000–Y.4049 | +| Definitions and terminologies | Y.4050–Y.4099 | +| Requirements and use cases | Y.4100–Y.4249 | +| Infrastructure, connectivity and networks | Y.4250–Y.4399 | +| Frameworks, architectures and protocols | Y.4400–Y.4549 | +| Services, applications, computation and data processing | Y.4550–Y.4699 | +| Management, control and performance | Y.4700–Y.4799 | +| Identification and security | Y.4800–Y.4899 | +| Evaluation and assessment | Y.4900–Y.4999 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.8275.1-202211-I_PDF-E/raw.md b/marked/G/T-REC-G.8275.1-202211-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..fbb700f7c3ba77fdbdad85e33f2aec95c8575196 --- /dev/null +++ b/marked/G/T-REC-G.8275.1-202211-I_PDF-E/raw.md @@ -0,0 +1,1859 @@ + + +# Recommendation**ITU-T G.827.1/Y.1369.1 (11/2022)** + +SERIES G: Transmission systems and media, digital systems and networks + +Packet over Transport aspects – Synchronization, quality and availability targets + +SERIES Y: Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities + +Internet protocol aspects – Transport + +--- + +### **Precision time protocol telecom profile for phase/time synchronization with full timing support from the network** + +![ITU logo](6ed175c791b5e156d9c98a8dbcc3318c_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font superimposed on the globe. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| Ethernet over Transport aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Synchronization, quality and availability targets | G.8200–G.8299 | +| Mobile network transport aspects | G.8300–G.8399 | +| Service Management | G.8600–G.8699 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.827.1/Y.1369.1 + +# Precision time protocol telecom profile for phase/time synchronization with full timing support from the network + +## Summary + +Recommendation ITU-T G.827.1/Y.1369.1 contains the ITU-T precision time protocol (PTP) profile for phase and time distribution with full timing support from the network. It provides the necessary details to utilize IEEE 1588 in a manner consistent with the architecture described in Recommendation ITU-T G.827.1/Y.1369. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|--------------------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.827.1/Y.1369.1 | 2014-07-22 | 15 | 11.1002/1000/12197 | +| 1.1 | ITU-T G.827.1/Y.1369.1 (2014) Cor. 1 | 2015-01-13 | 15 | 11.1002/1000/12397 | +| 2.0 | ITU-T G.827.1/Y.1369.1 | 2016-06-22 | 15 | 11.1002/1000/12815 | +| 2.1 | ITU-T G.827.1/Y.1369.1 (2016) Amd. 1 | 2017-08-29 | 15 | 11.1002/1000/13329 | +| 2.2 | ITU-T G.827.1/Y.1369.1 (2016) Amd. 2 | 2018-03-16 | 15 | 11.1002/1000/13553 | +| 2.3 | ITU-T G.827.1/Y.1369.1 (2016) Amd. 3 | 2019-08-29 | 15 | 11.1002/1000/14017 | +| 3.0 | ITU-T G.827.1/Y.1369.1 | 2020-03-15 | 15 | 11.1002/1000/14215 | +| 3.1 | ITU-T G.827.1/Y.1369.1 (2020) Amd. 1 | 2020-11-13 | 15 | 11.1002/1000/14543 | +| 3.2 | ITU-T G.827.1/Y.1369.1 (2020) Amd. 2 | 2021-06-29 | 15 | 11.1002/1000/14709 | +| 3.3 | ITU-T G.827.1/Y.1369.1 (2020) Amd. 3 | 2022-02-13 | 15 | 11.1002/1000/14913 | +| 4.0 | ITU-T G.827.1/Y.1369.1 | 2022-11-13 | 15 | 11.1002/1000/15131 | + +## Keywords + +IEEE 1588, phase, profile, PTP, time. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2023 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|---------|-------------------------------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 3 | +| 5 | Conventions ..... | 4 | +| 6 | Use of PTP for phase/time distribution ..... | 4 | +| 6.1 | High-level design requirements..... | 5 | +| 6.2 | PTP modes and options ..... | 5 | +| 6.3 | Protection aspects and Alternate BMCA..... | 9 | +| 6.4 | Phase/time traceability information..... | 16 | +| 7 | ITU-T PTP profile for phase/time distribution with full timing support from the network ..... | 19 | +| 8 | Security aspects ..... | 19 | +| Annex A | – ITU-T PTP profile for phase/time distribution with full timing support from the network ..... | 20 | +| A.1 | Profile identification ..... | 20 | +| A.2 | PTP attribute values..... | 20 | +| A.3 | PTP options ..... | 29 | +| A.4 | Best master clock algorithm options ..... | 30 | +| A.5 | Path delay measurement option (delay request/delay response) ..... | 30 | +| A.6 | Clock identity format..... | 30 | +| A.7 | Configuration management options ..... | 30 | +| A.8 | Security aspects ..... | 30 | +| A.9 | Other optional features of IEEE 1588 ..... | 30 | +| A.10 | PTP common header flags..... | 30 | +| A.11 | Profile version compatibility ..... | 32 | +| Annex B | – Options to establish the PTP topology with the Alternate BMCA..... | 33 | +| Annex C | – Inclusion of an external phase/time input interface in a T-BC..... | 34 | +| Annex D | – Path trace (optional) ..... | 35 | +| Annex E | – Synchronization uncertain indication (optional)..... | 36 | +| Annex F | – Use of stepsRemoved to limit reference chain (optional)..... | 37 | +| Annex G | – Monitoring alternate master time information provided by a peer PTP port (optional) ..... | 38 | +| G.1 | Use Case 1 – PASSIVE port monitoring MASTER port..... | 39 | +| G.2 | Use Case 2 –MASTER port monitoring PASSIVE port..... | 39 | +| G.3 | Use Case 3 –MASTER port monitoring MASTER port..... | 40 | + +| | Page | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------| +| Annex H – Transport of PTP over OTN ..... | 41 | +| Annex I – Transport PTP over MTN ..... | 42 | +| Annex J – Transport PTP over FlexE Links ..... | 43 | +| Annex K – Dynamic Monitoring based on PTSF (Optional) ..... | 44 | +| Appendix I – Considerations on the use of transparent clock..... | 45 | +| Appendix II – Considerations on the transmission of Delay_Req messages..... | 46 | +| Appendix III – Considerations on the choice of the PTP Ethernet multicast destination address ..... | 48 | +| Appendix IV – Considerations on the use of priority2 ..... | 49 | +| Appendix V – Description of PTP clock modes and associated contents of Announce messages ..... | 50 | +| Appendix VI – Operations over link aggregation..... | 51 | +| Appendix VII – Relationship between clockClass and holdover specification ..... | 52 | +| Appendix VIII – Considerations on a T-TSC connected to an end application ..... | 54 | +| Appendix IX – Calculation of offsetScaledLogVariance for T-GM timed by PRTC or ePRTC ..... | 55 | +| IX.1    Observation interval and TDEV noise generation..... | 55 | +| IX.2    Computation of PTP variance from TDEV ..... | 55 | +| IX.3    Computation of offsetScaledLogVariance from PTP variance ..... | 56 | +| Appendix X – Description of a T-BC extended clockClass application..... | 58 | +| X.1    Purpose of T-BC extended clockClass application ..... | 58 | +| X.2    DefaultDS data set member specifications under this extended application.. | 58 | +| Appendix XI – Considerations on native access equipment..... | 60 | +| Appendix XII – Monitoring alternate master time information provided by a peer PTP port..... | 61 | +| Appendix XIII – Considerations on the use of [IEEE 1588-2019]..... | 62 | +| Appendix XIV – Considerations in an environment of more than two PTP ports on a single PTP communication path when using transparent clocks and multicast addressing ..... | 63 | +| Appendix XV – Considerations of deploying ePRTC and PRTC in the network ..... | 65 | +| Bibliography..... | 66 | + +# Recommendation ITU-T G.827.1/Y.1369.1 + +# Precision time protocol telecom profile for phase/time synchronization with full timing support from the network + +# 1 Scope + +This Recommendation specifies a profile for telecommunication applications based on IEEE 1588 precision time protocol (PTP). The profile specifies the IEEE 1588 functions that are necessary to ensure network element interoperability for the delivery of accurate phase/time synchronization. The profile is based on the full timing support from the network architecture as described in [ITU-T G.827.5] and definitions described in [ITU-T G.826.0]. + +This version of the profile specifies the high-level design requirements, modes of operation for the exchange of PTP messages, the PTP protocol mapping, the best master clock algorithm (BMCA) options, as well as the PTP protocol configuration parameters. + +NOTE 1 – The parameters defined in this version of the profile are chosen based on the case where physical layer frequency support is provided, and the case without physical layer frequency support (i.e., PTP only) is for further study. + +This Recommendation also specifies some aspects necessary for use in a telecom environment that are outside the scope of and complement the PTP profile. + +An implementation compliant with this profile can claim compliance with either IEEE Std 1588-2008 [IEEE 1588-2008] or IEEE Std 1588-2019 [IEEE 1588-2019]. Considerations on the use of one or the other profile are provided in Appendix XIII. Compliance for a specific implementation with either the [IEEE 1588-2008] or [IEEE 1588-2019] versions of the standard should be stated when referring to this profile. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2020), *Interfaces for the optical transport network*. +- [ITU-T G.709.1] Recommendation ITU-T G.709.1/1331.1 (2018), *Flexible OTN short-reach interfaces*. +- [ITU-T G.781] Recommendation ITU-T G.781 (2020), *Synchronization layer functions for frequency synchronization based on the physical layer*. +- [ITU-T G.810] Recommendation ITU-T G.810 (1996), *Definitions and terminology for synchronization networks*. +- [ITU-T G.704.1] Recommendation ITU-T G.704.1/Y.1303 (2016), *Generic framing procedure*. +- [ITU-T G.826.0] Recommendation ITU-T G.826.0 (2022), *Definitions and terminology for synchronization in packet networks*. +- [ITU-T G.826.5.1] Recommendation ITU-T G.826.5.1/Y.1365.1 (2022), *Precision time protocol telecom profile for frequency synchronization*. + +- [ITU-T G.8271] Recommendation ITU-T G.8271/Y.1366 (2020), *Time and phase synchronization aspects of telecommunication networks*. +- [ITU-T G.8271.1] Recommendation ITU-T G.8271.1/Y.1366.1 (2022), *Network limits for time synchronization in packet networks with full timing support from the network*. +- [ITU-T G.8272] Recommendation ITU-T G.8272/Y.1367 (2018), *Timing characteristics of primary reference time clocks*. +- [ITU-T G.8272.1] Recommendation ITU-T G.8272.1/Y.1367.1 (2016), *Timing characteristics of enhanced primary reference time clocks*. +- [ITU-T G.8273] Recommendation ITU-T G.8273/Y.1368 (2018), *Framework of phase and time clocks*. +- [ITU-T G.8273.2] Recommendation ITU-T G.8273.2/Y.1368.2 (2020), *Timing characteristics of telecom boundary clocks and telecom time slave clocks for use with full timing support from the network*. +- [ITU-T G.8273.3] Recommendation ITU-T G.8273.3/Y.1368.3 (2020), *Timing characteristics of telecom transparent clocks for use with full timing support from the network*. +- [ITU-T G.8275] Recommendation ITU-T G.8275/Y.1369 (2020), *Architecture and requirements for packet-based time and phase distribution*. +- [ITU-T G.8312] Recommendation ITU-T G.8312 (2020), *Interfaces for metro transport networks*. +- [IEEE 1588] Either [IEEE 1588-2008] or [IEEE 1588-2019] depending on the specific implementation. See clause 5 Conventions for more details. +- [IEEE 1588-2008] IEEE 1588-2008, *IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems*. +- [IEEE 1588-2019] IEEE 1588-2019, *IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems*. +- [OIF FLEXE IA] Optical Internetworking Forum, IA OIF-FLEXE-02.2 (2021), *FlexE 2.2 Implementation Agreement*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +The terms and definitions used in this Recommendation are contained in [ITU-T G.810] and [ITU-T G.8260]. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following term: + +**3.2.1 special port:** A PTP special port is a PTP port that translates between the native timing mechanism of a medium and PTP. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|---------------------------------------| +| AVAR | Allan Variance | +| BC | Boundary Clock | +| BMCA | Best Master Clock Algorithm | +| EEC | synchronous Ethernet Equipment Clock | +| ePRTC | Enhanced Primary Reference Time Clock | +| EUI | Extended Unique Identifier | +| FlexE | Flex Ethernet | +| FPM | Flicker Phase Modulation | +| GM | Grandmaster | +| GNSS | Global Navigation Satellite System | +| LAG | Link Aggregation | +| MA-L | MAC Address – Large | +| MA-M | MAC Address – Medium | +| MA-S | MAC Address – Small | +| MTN | Metro Transport Network | +| MVAR | Modified Allan Variance | +| OC | Ordinary Clock | +| OEC | OTN Equipment Clock | +| OSMC | OTN synchronization messaging channel | +| OUI | Organizationally Unique Identifier | +| PRC | Primary Reference Clock | +| PRS | Primary Reference Source | +| PRTC | Primary Reference Time Clock | +| PSD | Power Spectral Density | +| PTP | Precision Time Protocol | +| PTSF | Packet Timing Signal Fail | +| QL | Quality Level | +| SDH | Synchronous Digital Hierarchy | +| SSM | Synchronization Status Message | +| SSU | Synchronization Supply Unit | +| SSU-A | primary level SSU | +| SSU-B | secondary level SSU | +| ST2 | Stratum 2 | +| ST3E | Stratum 3 Enhanced | +| T-BC | Telecom Boundary Clock | + +| | | +|-------|----------------------------| +| TC | Transparent Clock | +| T-GM | Telecom Grandmaster | +| T-TC | Telecom Transparent Clock | +| T-TSC | Telecom Time Slave Clock | +| TLV | Type Length Value | +| TVAR | Time Variance | +| VLAN | Virtual Local Area Network | +| WPM | White Phase Modulation | + +# 5 Conventions + +Within this Recommendation, the following conventions are used: the term PTP refers to the PTP defined in [IEEE 1588]. PTP messages used within this Recommendation are defined in [IEEE 1588] and are identified using italicized text. + +The term telecom boundary clock (T-BC) refers to a device consisting of a boundary clock (BC) as defined in [IEEE 1588] and this Recommendation, with additional performance characteristics defined in [ITU-T G.8273.2]. + +The term telecom transparent clock (T-TC) refers to a device consisting of a transparent clock (TC) as defined in [IEEE 1588] and this Recommendation, with additional performance characteristics defined in [ITU-T G.8273.3]. + +The term telecom grandmaster (T-GM) refers to a device consisting of a grandmaster (GM) clock as defined in [IEEE 1588] and this Recommendation, with additional performance characteristics for further study. + +The term telecom time slave clock (T-TSC) refers to a device consisting of a slave-only ordinary clock (OC) as defined in [IEEE 1588] and this Recommendation, with additional performance characteristics defined in the Annex C of [ITU-T G.8273.2]. + +The term primary reference time clock (PRTC) refers to the clock defined in [ITU-T G.8272]. The term enhanced primary reference time clock (ePRTC) refers to an enhanced version of the PRTC, which is being studied. + +Within this Recommendation, some requirements are stated as requiring compliance to [IEEE 1588]. For implementations based on [IEEE 1588-2008], the reference to [IEEE 1588] means compliance to [IEEE 1588-2008]. For implementations based on [IEEE 1588-2019], the reference to [IEEE 1588] means compliance to [IEEE 1588-2019]. Some of these references to [IEEE 1588] includes a specific clause number. In these cases, the clause number is the same in both [IEEE 1588-2008] and [IEEE 1588-2019]. If the requirements are in different clauses in the two versions of IEEE 1588, then the text of this Recommendation shall include the specific clause for [IEEE 1588-2008] and the specific cause for [IEEE 1588-2019]. + +# 6 Use of PTP for phase/time distribution + +The [IEEE 1588] standard defines the precision time protocol designed to enable accurate time transfer. It introduces the concept of "profile", whereby aspects of the protocol may be selected and specified for a particular application. + +A PTP profile has been defined in [ITU-T G.8265.1] to address applications requiring frequency synchronization only. This Recommendation defines another PTP profile, for telecom applications requiring accurate phase and time synchronization. It supports the specific architecture described in + +[ITU-T G.8275] in order to allow the distribution of phase/time with full timing support from the network and is based on [IEEE 1588]. + +In order to claim compliance with the telecom profile, the requirements of this Recommendation and the relevant requirements of [IEEE 1588], as referenced in Annex A, must be met. + +The detailed aspects related to the telecom profile are described in the following clauses, while the profile itself is contained in Annex A. It follows the general rules for profile specification developed in [IEEE 1588]. + +This PTP telecom profile defines the parameters from [IEEE 1588] to be used in order to guarantee protocol interoperability between implementations and specifies the optional features, default values of configurable attributes and mechanisms that must be supported. However, it does not guarantee that the performance requirements of a given application will be met. These performance aspects are defined in other ITU-T Recommendations and imply additional elements beyond the content of the PTP profile itself. + +## 6.1 High-level design requirements + +[IEEE 1588] states: + +*"The purpose of a PTP profile is to allow organizations to specify specific selections of attribute values and optional features of PTP that, when using the same transport protocol, inter-work and achieve a performance that meets the requirements of a particular application."* + +For operation in a telecom network, some additional criteria are also required to be consistent with standard telecom synchronization practices. Therefore, the PTP profile for time and phase distribution must meet the following high-level requirements: + +- 1) Mechanisms must be specified to allow interoperability between the various phase/time clocks belonging to the architecture defined in [ITU-T G.8275] and described in [ITU-T G.8273]. +- 2) Mechanisms must permit consistent operation over managed wide area telecom networks. +- 3) Packet-based mechanisms must allow the synchronization network to be designed and configured in a fixed arrangement. +- 4) Protection schemes used by packet-based systems must be based on standard telecom operational practice and allow telecom time slave clocks the ability to take phase and time from multiple geographically separate telecom grandmaster clocks. +- 5) Phase/time reference source selection based on received phase/time traceability and local priority, as well as automatic establishment of the phase/time synchronization network topology, should be permitted. + +## 6.2 PTP modes and options + +#### 6.2.1 PTP domains + +A domain consists of a logical grouping of clocks communicating with each other using the PTP protocol. + +PTP domains are used to partition a network within an administrative entity. The PTP messages and data sets are associated with a domain and therefore, the PTP protocol is independent for different domains. + +In this PTP telecom profile, the default PTP domain number is 24, and the range of applicable PTP domain numbers is {24 – 43}. + +NOTE – This range has been selected from the user-defined PTP domain number range defined in [IEEE 1588]. Although non-overlapping ranges have been considered for the different PTP telecom profiles + +so that interactions between the profiles are prevented, nothing precludes another industry from using the same user-defined PTP domain number range when defining a non-telecom PTP profile. It is the responsibility of the network operator to identify if the risk of unintentional interactions between PTP profiles exists, and to take the necessary actions to prevent such behaviour. + +### 6.2.2 PTP messages used in the profile + +This PTP profile uses the messages: *Sync*, *Follow\_Up*, *Announce*, *Delay\_Req*, and *Delay\_Resp*. + +The use of *Signalling* and *Management* messages is for further study. + +*Pdelay\_Req*, *Pdelay\_Resp*, and *Pdelay\_Resp\_Follow\_Up* messages are not used. + +### 6.2.3 Types of PTP clocks supported in the profile + +The ordinary clock (OC), boundary clock (BC) and transparent clock (TC) according to [IEEE 1588] are used in this profile. + +There are two types of OCs: + +- 1) An OC that can only be a grandmaster (T-GM according to the architecture defined in [ITU-T G.8275], and as included in [ITU-T G.8272]). +- 2) An OC that can only be a slave, i.e., slave-only OC (T-TSC according to the architecture defined in [ITU-T G.8275], and compliant with [ITU-T G.8273.2]). + +There are two types of BCs: + +- 1) A BC that can only be a grandmaster (T-GM according to the architecture defined in [ITU-T G.8275], and as included in [ITU-T G.8272]). +- 2) A BC that can become a grandmaster and can also be slaved to another PTP clock (T-BC according to architecture defined in [ITU-T G.8275] and compliant with [ITU-T G.8273.2]). + +NOTE – T-GM and grandmaster (GM) are different concepts; GM is a status defined in [IEEE 1588] that a PTP clock may obtain if it wins the best master clock algorithm (BMCA), while T-GM is a type of clock defined in the [ITU-T G.8275] architecture. + +The transparent clock used in this profile (T-TC according to the architecture defined in [ITU-T G.8275] and compliant with [ITU-T G.8273.3]) is the end-to-end transparent clock defined in [IEEE 1588]. It is not permitted to use peer-to-peer transparent clocks in this profile. + +The support of OTN ports on a T-TC is for further study. + +The support of metro transport network (MTN) ports as defined in [ITU-T G.8312] on a T-TC is for further study. + +The support of FlexE as defined in [OIF FlexE IA] on a T-TC is for further study. + +The mapping between these PTP clockTypes and the phase/time clocks defined in the [ITU-T G.8275] architecture is described in Table 1. + +**Table 1 – Mapping between [ITU-T G.8275.1] deviceTypes and PTP clockTypes** + +| deviceType from [ITU-T G.8275.1] | Description | clockType from [IEEE 1588] | +|----------------------------------|--------------------------------------------------------------------------------------------------------------------|----------------------------| +| T-GM | Master-only ordinary clock
(master with a single PTP port, always a GM, cannot be slaved to another PTP clock) | OC | +| | Master-only boundary clock
(master with multiple PTP ports, always a GM, cannot be slaved to another PTP clock) | BC | + +**Table 1 – Mapping between [ITU-T G.8275.1] deviceTypes and PTP clockTypes** + +| deviceType from [ITU-T G.8275.1] | Description | clockType from [IEEE 1588] | +|-----------------------------------------|----------------------------------------------------------------------------|-----------------------------------| +| T-BC | Boundary clock
(may become a GM, or may be slaved to another PTP clock) | BC | +| T-TSC | Slave-only ordinary clock
(always a slave, cannot become a GM) | OC | +| T-TC | Transparent clock | End-to-end TC | + +#### 6.2.3.1 Dataset member for PTP clocks supported in the profile + +A management system can configure and/or read the deviceType of a PTP clock; this allows the management node to configure other properties that are specific for that type of clock implemented in the equipment that is being deployed in the network. Equipment may support different types of clocks, and therefore deviceType is a configurable attribute. + +The data type for deviceType is Enumeration8, using the enumerated value per Table 2. + +**Table 2 – deviceType enumeration value** + +| deviceType from [ITU-T G.8275.1] | Enumeration value (hex) | +|-----------------------------------------|--------------------------------| +| T-GM | 0x10 | +| T-BC | 0x11 | +| T-TSC | 0x12 | +| T-TC | 0x13 | + +### 6.2.4 One-way versus two-way operation + +PTP operation must be two-way in this profile in order to transport phase/time synchronization, because propagation delay must be measured. Therefore, only two-way mode is allowed in this profile. + +#### 6.2.5 One-step versus two-step clock mode + +Both one-step and two-step clocks are supported in the profile. A clock compliant with the profile may use either a one-step clock or a two-step clock. + +To be compliant with [IEEE 1588], a slave port must be capable of receiving and processing messages from both one-step clocks and two-step clocks, without any particular configuration. + +#### 6.2.6 Ethernet multicast addressing for PTP messages + +For the PTP profile specified in this Recommendation, when using the PTP mapping defined in [IEEE 1588-2008] Annex F or [IEEE 1588-2019] Annex E, Ethernet multicast addressing is used for the Ethernet frames that carry the PTP messages. Both the non-forwardable multicast address 01-80-C2-00-00-0E and the forwardable multicast address 01-1B-19-00-00-00 are supported. + +A T-GM, T-BC, T-TSC or T-TC clock compliant with this profile must be capable of handling both the non-forwardable multicast address 01-80-C2-00-00-0E and the forwardable multicast address 01-1B-19-00-00-00 on all its PTP-capable Ethernet ports. + +For a T-GM, T-BC and T-TSC clock, the choice of the multicast address is made by configuration on a per-port basis; all the PTP messages of an Ethernet port must use the configured address for transmitting PTP messages to the remote PTP port. In case the remote PTP port is configured with the other address, the local PTP port must accept and process the received messages. + +The default address depends on the operator policy. See information in Appendix III. + +On transmission, the default mode for a T-TC that supports only Ethernet transport does not require any configuration: the PTP messages retransmitted by the T-TC must use the same multicast destination address as the received PTP message. It is mandatory to support this default mode in transmission. The default mode of transmission at an Ethernet port for a T-TC that supports both Ethernet and non-Ethernet ports is for further study. + +NOTE – This profile uses [IEEE 1588-2008] Annex F, *Transport of PTP over IEEE802.3/Ethernet*, or [IEEE 1588-2019] Annex E, *Transport of PTP over IEEE 802.3 transports* for the transport layer when the transport layer is Ethernet. In particular, according to the relevant Ethernet bridge models, the appropriate MAC address of the transmit Ethernet port is placed into the source address field of the header of the Ethernet frame encapsulating the PTP packets sent by any of the PTP clocks defined in this profile (i.e., T-GM, T-BC, T-TC or T-TSC). + +#### 6.2.7 PTP mapping + +This PTP telecom profile is based on the PTP mapping defined in + +- a) [IEEE 1588-2008] Annex F, *Transport of PTP over IEEE 802.3/Ethernet*, or [IEEE 1588-2019] Annex E, *Transport of PTP over IEEE 802.3 transports*, +- b) Annex H of this Recommendation, *Transport of PTP over OTN*, +- c) Annex I of this Recommendation, *Transport of PTP over MTN*, and +- d) Annex J of this Recommendation, *Transport of PTP over FlexE*. + +Therefore, a PTP clock compliant with the profile described in this Recommendation must be compliant with [IEEE 1588] for ports that use Ethernet transport, with Annex H of this Recommendation for ports that use OTN transport, with Annex I of this Recommendation for ports that use MTN, and with Annex J of this Recommendation for ports that use FlexE. This profile processes PTP messages with: + +- a) Ethernet multicast encapsulation when the transport layer is Ethernet; +- b) Either: + - i) GFP-F encapsulation and insertion into the OTUk OSMC or FlexO OSMC, or + - ii) Vendor-specific encapsulation into the OSC OSMC, + +when the transport layer is OTN; + +NOTE – OSC OSMC does not allow interoperability between different vendors. The test of this function is for further study. + +- c) Ethernet multicast encapsulation, and insertion into the MTN overhead per clause 9.2.5 of [ITU-T G.8312], when the transport layer is MTN; +- d) Ethernet multicast encapsulation, and insertion into the Synchronization Messaging Channel per clause 7.3.5 of [OIF FlexE IA], when the transport layer is FlexE. + +PTP messages with other encapsulations should be forwarded based on the forwarding rules of the respective transport. + +The transportSpecific field is used in this profile and must be set to "0". + +In the scenarios currently considered, e.g., based on full timing support with T-BC and T-TC, the insertion of a virtual local area network (VLAN) tag in the frames carrying PTP messages over + +Ethernet is not allowed for T-GMs, T-BCs and T-TSC. In this case, when receiving a PTP message within a frame containing a VLAN tag, this frame must be discarded by the T-GM, T-BC, and T-TSC. + +Some specific T-TC based configurations are discussed in Appendix I. + +Using VLAN tags in other scenarios is for further study. + +#### 6.2.8 Message rates + +Within the scope of the profile, the following messages can be used, and the corresponding indicated nominal rates shall be respected: + +- *Sync* messages (if used, *Follow\_up* messages will have the same rate) – nominal rate: 16 packets-per-second. +- *Delay\_Req/Delay\_Resp* messages – nominal rate: 16 packets-per-second. +- *Announce* messages – nominal rate: 8 packets-per-second. + +Inter-message interval requirements shall also be respected for the transmission of *Sync* (clause 9.5.9 of [IEEE 1588]) and *Announce* (clause 9.5.8 of [IEEE 1588]) messages. In addition, the time between successive *Sync* messages shall not exceed twice the mean *Sync* interval specified above, and the time between successive *Announce* messages shall not exceed twice the mean *Announce* interval specified above. + +The transmission of *Delay\_Req* messages is specified in clause 9.5.11.2 of [IEEE 1588]. + +In addition to clause 9.5.11.2 of [IEEE 1588-2008] (first and second dashed items) or of [IEEE 1588-2019] (items (a) and (b)), a clock compliant to this profile shall follow one of the following options: + +- Transmission time requirements according to clause 9.5.11.2 of [IEEE 1588-2008] (third dashed item) or of [IEEE 1588-2019] (item (c), subitem (1)), using an implementation-specific distribution. In this case, the PTP node shall, with 90% confidence, issue *Delay\_Req* messages with inter-message intervals within $\pm 30\%$ of $2^{\log\text{MinDelayReqInterval}}$ seconds. +- Transmission time requirements specified in clause 9.5.11.2 of [IEEE 1588-2008] (forth dashed item) or of [IEEE 1588-2019] (item (c), subitem (2)). + +In addition, the time between successive *Delay\_Req* messages shall not exceed $2^{\log\text{MinDelayReqInterval}+1}$ seconds. + +As per clause 9.5.12 of [IEEE 1588], the Master sets the *logMessageInterval* in the header of *Delay\_Resp* messages to a value accepted by the Master. In this profile that value is $-4$ (16 pps). + +Additional background information concerning the *Delay\_Req* message transmission specified in clause 9.5.11.2 of [IEEE 1588] is included in Appendix II. + +The use of *signalling* and *management* messages is for further study. + +## 6.3 Protection aspects and Alternate BMCA + +### 6.3.1 Alternate BMCA + +The PTP profile specified in this Recommendation uses an Alternate BMCA, as described in clause 9.3.1 of [IEEE 1588]. This Alternate BMCA differs from the default BMCA of [IEEE 1588] as follows: + +- a) This profile uses the per port Boolean attribute *masterOnly* as specified in Annex E of [ITU-T G.8275]. +- b) The profile uses the per port Boolean attribute *notMaster* as specified in Annex E of [ITU-T G.8275]. + +- c) The profile allows for multiple clocks to be active GMs simultaneously (clocks with clockClass less than 128 cannot be a slave). If there are multiple active GMs, every clock that is not a GM is synchronized by a single GM in the PTP domain. +- d) The per-port attribute localPriority is assigned to each port r of a clock and is used in the determination of Erbest and Ebest. Each parent clock or foreign master clock data set, whose *Announce* information was received on the port r, is appended with the localPriority attribute of the local port r before the data set comparison defined in Figure 2 and Figure 3 below is invoked. The localPriority attribute is not transmitted in *Announce* messages. This attribute is used as a tie-breaker in the data set comparison algorithm, in the event that all other previous attributes of the data sets being compared are equal. The localPriority attribute is set via the configurable, unsigned integer, port data set member portDS.localPriority. The data type for this attribute is UInt8. The range of values for this attribute is {1-255}. The default value for this attribute is 128. A clock compliant with this PTP profile is allowed to support a subset of the values defined in the range. +- e) The attribute localPriority is assigned to the local clock, to be used if needed when the data associated with the local clock, D0, is compared with data on another potential GM received via an *Announce* message. The local clock localPriority attribute is set via the configurable, unsigned integer, default data set member defaultDS.localPriority. The data type for this attribute is UInt8. The range of values for this attribute is {1-255}. The default value for this attribute is 128. A clock compliant with this PTP profile is allowed to support a subset of the values defined in the range. +- f) The data set comparison algorithm is modified according to Figures 2 and 3 in clause 6.3.7. + NOTE 1 – For a T-BC, the ports for which the masterOnly attribute is FALSE should be selected according to the network synchronization plan. One typical use case where this parameter should remain TRUE is to prevent timing from propagating from the access portion of the network to the core portion of the network. + NOTE 2 – The use of masterOnly is intended primarily to be used in two scenarios: + - 1) A PTP port of a T-GM; + - 2) A PTP port of a T-BC that is facing the 'downstream' direction towards the access portion of a tree topology. + +The use of the masterOnly parameter in other scenarios, such as on PTP ports participating in a ring architecture, may result in unintended operation, especially during re-configuration or topology changes. + +#### 6.3.2 Considerations on the use of the localPriority attributes + +The localPriority attributes provide a powerful tool in defining the synchronization network architecture. + +The use of the default values for these attributes as defined by the Alternate BMCA results in a timing-loop free synchronization network. + +Proper planning will be mandatory to avoid timing-loops when configuring values different from the default ones. + +#### 6.3.3 Static clock attribute priority1 + +In this PTP profile, the clock attribute priority1 is static. It is initialized to a default value equal to the midpoint value, 128, of its range, and this value must not be changed. + +The priority1 parameter is not used in this version of the PTP telecom profile. Future versions may consider using this attribute, this is for further study. + +#### 6.3.4 Clock attribute priority2 + +In this PTP profile, the clock attribute priority2 is configurable. + +It is initialized to a default value, equal for T-GM and T-BC clocks to the midpoint value, 128, of its range {0-255}. The default value for T-TSC clocks is 255, and the range is {255}. + +A T-GM or T-BC compliant with this PTP profile must support all the values of priority2 defined in the range. A T-TSC compliant with this profile must support, on reception, all the values of priority2 defined in the full [IEEE 1588] range (i.e., {0-255}). + +Appendix IV describes possible use cases for the priority2 attribute; Appendix X describes possible use cases for the priority2 attribute under Note 3 of Table 3; other cases are for further study. + +#### 6.3.5 Other clock attributes + +A PTP clock compliant with this PTP profile must support all the values of clockClass, clockAccuracy, and offsetScaledLogVariance upon reception [shall not discard] defined in the full [IEEE 1588] range. + +The applicable values of the clock attribute clockClass are specified in clause 6.4. + +NOTE – It is not expected that equipment compliant to this profile and deployed in an ITU-T G.8275.1 network will receive clockClass values not specified in Table 3 or Table 5. If a clockClass value not specified in Table 3 or Table 5 is received, then the equipment may raise an implementation specific alarm. Future revisions of this profile may include clockClass values not defined in Table 3 or Table 5. + +The following values of the clock attribute clockAccuracy apply for the following situations: + +- 0x20 for a T-GM connected to an enhanced primary reference time clock (ePRTC) in locked-mode (i.e., ePRTC traceable to global navigation satellite system (GNSS)); +- 0x21 for a T-GM connected to a PRTC in locked-mode (i.e., PRTC traceable to GNSS) or a T-GM connected to an ePRTC where the ePRTC is in phase/time holdover within ITU-T G.8272.1 ePRTC-A specification as specified in Table 3 of [ITU-T G.8272.1]; +- 0xFE for a T-GM not connected to an ePRTC nor a PRTC in locked-mode, or a T-GM connected to an ePRTC in phase/time holdover but outside the holdover specification in Table 3 of [ITU-T G.8272.1]; +- 0xFE for a T-BC, all the time. + +The following values of the clock attribute offsetScaledLogVariance apply for the following situations: + +- 0x4B32 for a T-GM connected to an ePRTC in locked-mode (i.e., ePRTC traceable to GNSS). This corresponds to TDEV of 10 ns, at observation interval of 1 000 000 s. The corresponding value of PTP Variance (PTPVAR) is $1.271 \times 10^{-16} \text{ s}^2$ (see Appendix IX); +- 0x4E5D for a T-GM connected to a PRTC in locked-mode (i.e., PRTC traceable to GNSS). This corresponds to TDEV of 30 ns, at observation interval of 10 000 s. The corresponding value of PTP Variance (PTPVAR) is $1.144 \times 10^{-15} \text{ s}^2$ (see Appendix IX); +- 0xFFFF for a T-GM not connected to an ePRTC in locked-mode nor to a PRTC in locked-mode; +- 0xFFFF for a T-BC, all the time. + +### 6.3.6 State decision algorithm + +The state decision algorithm applicable to the Alternate BMCA of the PTP profile specified in this Recommendation is given in Figure 1. After a decision is reached by use of this algorithm, the data sets of the local clock are updated as specified in clause 9.3.5 of [IEEE 1588]. Details on the use of the algorithm are given in clause 9.3.3 of [IEEE 1588]. + +#### 6.3.7 Data set comparison algorithm + +The data set comparison algorithm for the Alternate BMCA of the PTP profile specified in this Recommendation is given in Figures 2 and 3 below. With this algorithm, one clock is compared with another using the data sets representing those clocks, appended with the localPriority attribute. Details on the use of the algorithm are given in clause 9.3.4 of [IEEE 1588]. + +If either of the data sets, A or B, in Figures 2 and 3 contain the data of the parent clock or a foreign master clock, the corresponding localPriority for its data set is the localPriority of the local port $r$ on which the information from that parent clock or foreign master clock has been received (see item (d) of clause 6.3.1). + +If either of the data sets, A or B, in Figures 2 and 3 contain the data of the local clock, $D_0$ , the corresponding localPriority for that data set is the localPriority of the local clock (see item (e) of clause 6.3.1). + +NOTE 1 – It is recommended that the entire data set comparison algorithm described in Figures 2 and 3 be implemented even if some parameters are currently static, because they may be used in future versions of this Recommendation. + +NOTE 2 – The block in Figure 2 "GM clockClass of A is 127 or less" enables different T-BCs in the network to be synchronized by different T-GMs when multiple T-GMs are deployed. + +NOTE 3 – If portDS.SF is TRUE on port $r$ , then the PTP port should set the respective $E_{\text{rbest}}$ to the empty set. As a result, the computation of $E_{\text{best}}$ will not use the information contained in any Announce messages received on the port $r$ . Signal fail (SF) is described in clause 6.3.9. + +![Flowchart of the state decision algorithm for Alternate BMCA. The process starts with 'State decision algorithm for port 'r' on clock C0'. It checks if E_best is empty and the port is in LISTENING state. If yes, it remains in LISTENING. If no, it checks if D0 is Class 1 through 127. If yes, it checks if D0 is better or better by topology than E_rbest. If yes, it becomes BMC_MASTER (D0) M1. If no, it becomes BMC_PASSIVE (E_rbest) P1. If D0 is not Class 1 through 127, it checks if D0 is better or better by topology than E_best. If yes, it becomes BMC_MASTER (D0) M2. If no, it proceeds to check if E_best received on port 'r'. If yes, it becomes BMC_SLAVE (E_best = E_rbest) S1. If no, it checks if E_best is better by topology than E_rbest. If yes, it becomes BMC_PASSIVE (E_rbest) P2. If no, it becomes BMC_MASTER (E_best) M3. A key indicates that recommended states are in shaded boxes.](9c6461e1e94afae4dec455e69a2ce152_img.jpg) + +``` + +graph TD + Start([State decision algorithm for port 'r' on clock C0]) --> D1{E_best is the empty set AND Port state is LISTENING} + D1 -- Yes --> R1([Remain in LISTENING state]) + D1 -- No --> D2{D0 is Class 1 through 127} + D2 -- Yes --> D3{D0 better or better by topology than E_rbest} + D2 -- No --> D4{D0 better or better by topology than E_best} + D3 -- Yes --> M1([BMC_MASTER D0 M1]) + D3 -- No --> P1([BMC_PASSIVE E_rbest P1]) + D4 -- Yes --> M2([BMC_MASTER D0 M2]) + D4 -- No --> D5{E_best received on port 'r'} + D5 -- Yes --> S1([BMC_SLAVE E_best = E_rbest S1]) + D5 -- No --> D6{E_best better by topology than E_rbest} + D6 -- Yes --> P2([BMC_PASSIVE E_rbest P2]) + D6 -- No --> M3([BMC_MASTER E_best M3]) + +``` + +KEY + +Recommended state (basis for data set updates) + +G.8275.1-Y.1369.1(16)\_F01 + +Flowchart of the state decision algorithm for Alternate BMCA. The process starts with 'State decision algorithm for port 'r' on clock C0'. It checks if E\_best is empty and the port is in LISTENING state. If yes, it remains in LISTENING. If no, it checks if D0 is Class 1 through 127. If yes, it checks if D0 is better or better by topology than E\_rbest. If yes, it becomes BMC\_MASTER (D0) M1. If no, it becomes BMC\_PASSIVE (E\_rbest) P1. If D0 is not Class 1 through 127, it checks if D0 is better or better by topology than E\_best. If yes, it becomes BMC\_MASTER (D0) M2. If no, it proceeds to check if E\_best received on port 'r'. If yes, it becomes BMC\_SLAVE (E\_best = E\_rbest) S1. If no, it checks if E\_best is better by topology than E\_rbest. If yes, it becomes BMC\_PASSIVE (E\_rbest) P2. If no, it becomes BMC\_MASTER (E\_best) M3. A key indicates that recommended states are in shaded boxes. + +Figure 1 – State decision algorithm for Alternate BMCA + +![Flowchart of the data set comparison algorithm for Alternate BMCA. It starts with 'Compare data set A to B' and proceeds through a series of decision diamonds: 'Compare GM clockClass values of A and B', 'Compare GM clockAccuracy values of A and B', 'Compare GM offsetScaledLogVariance values of A and B', 'Compare GM priority2 values of A and B', 'Compare localPriority values of A and B', 'GM clockClass of A is 127 or less', and 'Compare GM clockIdentity values of A and B'. Each diamond has 'A > B', 'A = B', and 'A < B' branches. The 'A > B' branches lead to 'Return B better than A', the 'A = B' branches lead to a connector 'x', and the 'A < B' branches lead to 'Return A better than B'. A connector 'x' is also reached if 'GM clockClass of A is 127 or less' is 'Yes'.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +``` + +graph TD + Start([Compare data set A to B]) --> D1{Compare GM clockClass values of A and B} + D1 -- A > B --> EndB([Return B better than A]) + D1 -- A = B --> D2{Compare GM clockAccuracy values of A and B} + D1 -- A < B --> EndA([Return A better than B]) + D2 -- A > B --> EndB + D2 -- A = B --> D3{Compare GM offsetScaledLogVariance values of A and B} + D2 -- A < B --> EndA + D3 -- A > B --> EndB + D3 -- A = B --> D4{Compare GM priority2 values of A and B} + D3 -- A < B --> EndA + D4 -- A > B --> EndB + D4 -- A = B --> D5{Compare localPriority values of A and B} + D4 -- A < B --> EndA + D5 -- A > B --> EndB + D5 -- A = B --> D6{GM clockClass of A is 127 or less} + D5 -- A < B --> EndA + D6 -- Yes --> X1((x)) + D6 -- No --> D7{Compare GM clockIdentity values of A and B} + D7 -- A > B --> EndB + D7 -- A = B --> X2((x)) + D7 -- A < B --> EndA + +``` + +G.8275.1-Y.1369.1(16)\_F02 + +Flowchart of the data set comparison algorithm for Alternate BMCA. It starts with 'Compare data set A to B' and proceeds through a series of decision diamonds: 'Compare GM clockClass values of A and B', 'Compare GM clockAccuracy values of A and B', 'Compare GM offsetScaledLogVariance values of A and B', 'Compare GM priority2 values of A and B', 'Compare localPriority values of A and B', 'GM clockClass of A is 127 or less', and 'Compare GM clockIdentity values of A and B'. Each diamond has 'A > B', 'A = B', and 'A < B' branches. The 'A > B' branches lead to 'Return B better than A', the 'A = B' branches lead to a connector 'x', and the 'A < B' branches lead to 'Return A better than B'. A connector 'x' is also reached if 'GM clockClass of A is 127 or less' is 'Yes'. + +**Figure 2 – Data set comparison algorithm, part 1, for Alternate BMCA** + +![Flowchart of the data set comparison algorithm, part 2, for Alternate BMCA. The process starts at node 'x' and proceeds through a series of decision diamonds and action ovals. The first decision is 'Compare stepsRemoved values of A and B'. If A > B+1, it goes to 'Return B better than A' (Receiver < Sender). If A+1 < B, it goes to 'Return A better than B' (Receiver < Sender). If A is within 1 of B, it proceeds to the next decision: 'Compare portIdentities of receiver of A and sender of A' vs 'Compare portIdentities of receiver of B and sender of B'. If A > B, it goes to 'Compare portIdentities of sender of A and sender of B'. If A < B, it goes to 'Return A better by topology than B' (Receiver > Sender). If A = B, it proceeds to 'Compare portNumbers of receiver of A and receiver of B'. If A > B, it goes to 'Return B better by topology than A' (Receiver > Sender). If A < B, it goes to 'Return A better by topology than B' (Receiver > Sender). If A = B, it goes to 'error-2'. If Receiver = Sender at any point, it goes to 'error-1'.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +``` + +graph TD + x((x)) --> D1{Compare stepsRemoved values of A and B} + D1 -- "A > B+1" --> O1([Return B better than A]) + O1 -- "Receiver < Sender" --> D2{Compare portIdentities of receiver of A and sender of A} + D1 -- "A+1 < B" --> O2([Return A better than B]) + O2 -- "Receiver < Sender" --> D3{Compare portIdentities of receiver of B and sender of B} + D1 -- "A within 1 of B" --> D4{Compare portIdentities of receiver of A and sender of A} + D4 -- "A > B" --> D5{Compare portIdentities of sender of A and sender of B} + D4 -- "A < B" --> D3 + D4 -- "A = B" --> D6{Compare portNumbers of receiver of A and receiver of B} + D5 -- "A > B" --> O3([Return B better by topology than A]) + O3 -- "Receiver > Sender" --> D2 + D5 -- "A < B" --> O4([Return A better by topology than B]) + O4 -- "Receiver > Sender" --> D3 + D5 -- "A = B" --> D6 + D6 -- "A > B" --> O3 + D6 -- "A < B" --> O4 + D6 -- "A = B" --> E2([error-2]) + D2 -- "Receiver < Sender" --> O1 + D2 -- "Receiver > Sender" --> O3 + D2 -- "Receiver = Sender" --> E1a([error-1]) + D3 -- "Receiver < Sender" --> O2 + D3 -- "Receiver > Sender" --> O4 + D3 -- "Receiver = Sender" --> E1b([error-1]) + +``` + +Flowchart of the data set comparison algorithm, part 2, for Alternate BMCA. The process starts at node 'x' and proceeds through a series of decision diamonds and action ovals. The first decision is 'Compare stepsRemoved values of A and B'. If A > B+1, it goes to 'Return B better than A' (Receiver < Sender). If A+1 < B, it goes to 'Return A better than B' (Receiver < Sender). If A is within 1 of B, it proceeds to the next decision: 'Compare portIdentities of receiver of A and sender of A' vs 'Compare portIdentities of receiver of B and sender of B'. If A > B, it goes to 'Compare portIdentities of sender of A and sender of B'. If A < B, it goes to 'Return A better by topology than B' (Receiver > Sender). If A = B, it proceeds to 'Compare portNumbers of receiver of A and receiver of B'. If A > B, it goes to 'Return B better by topology than A' (Receiver > Sender). If A < B, it goes to 'Return A better by topology than B' (Receiver > Sender). If A = B, it goes to 'error-2'. If Receiver = Sender at any point, it goes to 'error-1'. + +**Figure 3 – Data set comparison algorithm, part 2, for Alternate BMCA** + +#### 6.3.8 Unused PTP fields + +Some PTP fields are not used in this PTP profile. This clause defines the actions applicable to these unused PTP fields. + +Table A.8 in clause A.10 of this Recommendation defines the PTP common header flag values, and whether or not each flag is used in this profile. + +In addition, the following fields are not used in this profile: + +- The "controlField" in the common header of PTP messages is not used in this profile. This field must be ignored by the receiver for all types of PTP messages; +- The "priority1" field in the *Announce* message is not used and must be set to a fixed value specified in clause 6.3.3. + +When a PTP clock receives a PTP message with a field, whose use is not specified in this PTP profile, containing a value outside the allowed range, then this field of the PTP message must be ignored, without discarding the PTP message. + +As an example, a PTP clock compliant with this PTP profile must ignore on reception the field value for the following fields. A clock compliant with this PTP profile must not update its local data sets with the ingress value for these fields: + +- flagField – alternateMasterFlag; +- flagField – unicastFlag; +- flagField – PTP profile Specific 1; +- flagField – PTP profile Specific 2. + +When a PTP clock receives a PTP message with a field, whose use is specified in this PTP profile, containing a value outside the allowed range for reception, then this entire PTP message must be discarded. The allowed range for a parameter on reception is the same as the range for the corresponding default dataset parameter, except for the attributes clockClass, clockAccuracy, offsetScaledLogVariance, and priority2 (see clauses 6.3.4 and 6.3.5). + +As an example, a compliant clock must discard on reception the ingress packet (General and Event messages) when any of the following fields are outside of the allowed range for the profile: + +- domainNumber; +- versionPTP. + +The clock's local data set must not be updated with the ingress value. + +NOTE 1 – If a clock receives an *Announce* message with the "priority1" field set to a value other than 128, and if the clock advertising this value is selected as the GM, then 128 must be re-advertised by the receiving clock. The unused attribute priority1 is ignored by the receiving clock for the purpose of the Alternate BMCA. + +NOTE 2 – The allowed ranges for reception for the clock attributes priority2, clockClass, clockAccuracy, and offsetScaledLogVariance are the respective full [IEEE 1588] ranges, see clauses 6.3.4 and 6.3.5. + +#### 6.3.9 Packet timing signal fail + +This clause is optional but, if implemented, it is necessary for the equipment to conform to the requirements contained herein. An implementation may support all, none, or a subset of these types of PTSF. + +This clause defines the notion of packet timing signal fail (PTSF), which corresponds to a signal indicating a failure of the PTP packet timing signal received by a port. + +Three types of PTSF may be raised in a PTP clock: + +- 1) PTSF-lossOfTimingMessages, lack of reception of PTP timing messages from a master (loss of the packet timing signal): if the slave or passive port of a PTP clock no longer receives the timing messages sent by a master (i.e., *Sync* and subsequently *Follow\_Up* and *Delay\_Resp* messages), then a PTSF-lossOfTimingMessages associated with this master must occur. A timeout period for reception of *Sync* messages or *Delay\_Resp* messages (i.e., *syncReceiptTimeout* and *delayRespReceiptTimeout*) for these timing messages must be implemented in the PTP port before triggering the PTSF-lossOfTimingMessages (the range and default value of these timeout parameters are defined in Table A.5). + +The value of *syncReceiptTimeout* shall specify the number of *Sync* message intervals that have to pass without receipt of a *Sync* and, if the *twoStep* flag of the *Sync* message is TRUE, a *Follow\_Up* message before the triggering of the PTSF-lossOfTimingMessages event. + +The value of *delayRespReceiptTimeout* shall specify the number of *Delay\_Req* message intervals that have to pass without receipt of a *Delay\_Resp* message before the triggering of the PTSF-lossOfTimingMessages event. + +When the PTP port enters the UNCALIBRATED or PASSIVE state, a timer should be activated. + +- 2) PTSF-unusable, unusable PTP packet timing signal received by the slave or passive port of a PTP clock, exceeding the input tolerance of the PTP clock (noisy packet timing signal): if the PTP packet timing signal is not usable for the PTP clock to achieve the performance target (e.g., excessive noise or abnormal PTP timestamps), then a PTSF-unusable associated with this master must occur. The criteria used to determine that the packet timing signal is not suitable to be used are for further study. + +- 3) PTSF-synchronizationUncertain: uncertain timing signal received by the slave or passive port of a PTP clock, if the synchronizationUncertain flag of an Announce message received from an upstream clock is TRUE, a PTSF-synchronizationUncertain associated with this master must occur. + +When a PTSF occurs, the clock may set the PTP portDS.SF to TRUE and generate a state decision event, which triggers the running of the alternate BMCA. As described in clause 6.3.7 a value of portDS.SF of TRUE can be used to exclude PTP ports from the alternate BMCA selection process. An implementation may set the PTP portDS.SF to TRUE for only a subset of PTSF listed above; that is, the implementation may set portDS.SF to TRUE for some PTSF and leave portDS.SF as FALSE for others. For example, when PTSF-synchronizationUncertain is raised, if portDS.SF is not set to TRUE, then this would allow the PTP topology to be built as described in Annex D of [ITU-T G.8275]. + +NOTE 1 – See Appendix XIV for more discussion of deployments with transparent clocks. + +NOTE 2 – Annex K includes an option for dynamic monitoring by a PTP port when its portDS.SF has been set to TRUE due to PTSF. + +## 6.4 Phase/time traceability information + +To deliver phase/time traceability information, the clockClass values described in Table 3 must be used in this PTP telecom profile. Additional information for interworking purposes is provided in Table 5. + +The frequencyTraceable flag present in the header of the PTP messages is defined in this profile as follows: if the PTP clock + +- is a T-GM that is traceable to a PRTC in locked mode or +- is a T-GM or a T-BC in holdover or free-run mode that has a timescale traceable to a primary reference clock (PRC), + +then this parameter must be set to TRUE, otherwise it must be FALSE. This flag is not used in the Alternate BMCA defined in clause 6.3; the values provided for this flag in Table 3 can be used by a network operator for monitoring purposes or by end applications to take definitive action as described in Appendix VIII. + +When a T-GM first enters holdover, it downgrades the clockClass value that it uses to 7. It then calculates if the time error at its output is still within the holdover specification. When the T-GM determines that the time error at its output has exceeded the holdover specification, it downgrades the clockClass value that it uses to 140, 150 or 160 depending on the quality of its frequency reference (internal oscillator or received physical layer frequency signal on an external interface). + +When a T-BC first enters holdover, it downgrades the clockClass value that it uses to 135. It then calculates if the time error at its output is still within the holdover specification. When the T-BC determines that the time error at its output has exceeded the holdover specification, it downgrades the clockClass value that it uses to 165 (internal oscillator or received physical layer frequency signal on an external interface). + +NOTE 1 – The applicable holdover specification depends on the design and budgeting of the synchronization network. See Appendix V of [ITU-T G.8271.1] for examples of network budgeting. A typical value for the holdover budget, described in the failure scenario (b) depicted in [ITU-T G.8271.1] Table V.1, when using the T-GM or T-BC for holdover while still meeting a total time error of 1.5 µs, is 400 ns. + +NOTE 2 – When the term clockClass is used with respect to the property of the individual PTP clock (T-GM, T-BC, T-TSC) it is referring to data set member defaultDS.clockQuality.clockClass. + +NOTE 3 – For the T-BC in locked mode, the traceability information of the currently selected best master clock will be passed to the downstream nodes, as per PTP. This means that the attributes and flags in the PTP header will always reflect the phase/time traceability information from the current parent clock, regardless of + +the frequency traceability of the T-BC's physical layer clock. Failure scenarios including holdover are for further study. + +**Table 3 – Applicable clockClass values** + +| Phase/time traceability description | defaultDS.
clockQuality.
clockClass | frequencyTraceable
flag | timeTraceable
flag | +|--------------------------------------------------------------------------------------------------------|-------------------------------------------|----------------------------|-----------------------| +| T-GM connected to a PRTC in locked mode (e.g., PRTC traceable to GNSS) | 6 | TRUE | TRUE | +| T-GM in holdover, within holdover specification, traceable to Category 1 frequency source (Note 1) | 7 | TRUE | TRUE | +| T-GM in holdover, within holdover specification, non-traceable to Category 1 frequency source (Note 1) | 7 | FALSE | TRUE | +| T-BC in holdover, within holdover specification, traceable to Category 1 frequency source (Note 1) | 135 | TRUE | TRUE | +| T-BC in holdover, within holdover specification, non-traceable to Category 1 frequency source (Note 1) | 135 | FALSE | TRUE | +| T-GM in holdover, out of holdover specification, traceable to Category 1 frequency source (Note 1) | 140 | TRUE | FALSE | +| T-GM in holdover, out of holdover specification, traceable to Category 2 frequency source (Note 1) | 150 | FALSE | FALSE | +| T-GM in holdover, out of holdover specification, traceable to Category 3 frequency source (Note 1) | 160 | FALSE | FALSE | +| T-BC in holdover, out of holdover specification (Note 1) | 165 | (Note 2) | FALSE | +| T-GM or T-BC in free-run mode | 248 | (Note 2) | FALSE | +| Slave only OC (does not send Announce messages) | 255 | (Note 2) | As per PTP | + +NOTE 1 – The holdover specification threshold controlling the time spent advertising clockClass values 7 or 135 could be set to zero so that the T-GM or T-BC would advertise a degraded clockClass value directly after losing traceability to a PRTC. In this case, initially after advertising clockClass values 140, 150, 160, or 165, a clock may still be within the holdover specification. + +NOTE 2 – The frequencyTraceable flag may be TRUE or FALSE, depending on the availability of a PRC-traceable physical layer frequency input signal. + +NOTE 3 – As an option, the clockClass range of a T-BC can be extended from (135, 165, 248) to (135, 140, 150, 160, 165, 248) for some cases, where (a) 140, 150, 160, and 165 are related to the quality of the frequency reference, (b) the applicable circumstances of 140, 150, and 160 are the same as for the T-GM, and (c) 165 corresponds to synchronous Ethernet equipment clock (EEC) or the OTN equipment clock (OEC). Details are in Appendix X. If this option is used, then in a single PTP domain, all PTP clocks should implement this option (and should not be intermixed with clocks that do not implement this option). Details are for further study. + +NOTE 4 – The term "holdover" in this table refers to "time holdover". + +**Table 3 – Applicable clockClass values** + +| | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NOTE 5 – Refer to Appendix VII for more information about the behaviour of a T-BC that was previously synchronizing to a T-GM or a T-BC that is advertising 'within holdover specification', 'out of holdover specification', or 'free-run mode'. | +| NOTE 6 – A T-BC that is locked to a PRTC through virtual PTP port (refer to Figure II.1 in ITU-T G.8275, Appendix II) and meets the holdover performance requirements of a T-GM, may follow the clockClass assignments of a T-GM if the T-BC enters holdover (a) due to the loss of the connectivity to that PRTC, and (b) no other PTP source is available. | + +Table 4 describes how the clock quality levels (QLs) defined in [ITU-T G.781] are mapped to Category 1, 2 and 3 frequency sources used in Table 3. + +**Table 4 – Mapping of [ITU-T G.781] clock QLs to Category 1, 2, 3 frequency sources** + +| Category
(in Table 3 and 5) | ITU-T G.781
option I QLs | ITU-T G.781
option II QLs | +|--------------------------------|------------------------------------|------------------------------------| +| Category 1 frequency source | QL-ePRTC, QL-PRTC, QL-ePRC, QL-PRC | QL-ePRTC, QL-PRTC, QL-ePRC, QL-PRS | +| Category 2 frequency source | QL-SSU-A | QL-ST2 | +| Category 3 frequency source | QL-SSU-B | QL-ST3E | + +NOTE – Other frequency source categories, while not used in Table 3, are possible. An example is a category containing QL-EEC1 and QL-EEC2. + +NOTE 4 – The case of a T-BC acting as a GM, with an external phase/time input coming from a PRTC, is handled by means of a virtual PTP port with associated $E_{rbest}$ attributes as described in Annex C of this Recommendation. The general case of a T-BC with a phase/time external synchronization input different from PRTC is for further study. + +Table 5 presents a subset of the clockClass values of Table 3 based on the quality of the frequency reference, and the mapping of the corresponding values used by some equipment deployed prior to this Recommendation. + +NOTE 5 – When interoperability with equipment deployed prior to this Recommendation is needed, both sets of clockClass values would need to be supported. Other aspects may be required for full interoperability. + +**Table 5 – clockClass values for equipment deployed prior to this Recommendation** + +| Phase/time traceability description | Values
defined in
Table 3 | Values prior to
this Rec. | +|----------------------------------------------------------------------------------------------------|---------------------------------|------------------------------| +| T-GM connected to a PRTC in locked mode (e.g., PRTC traceable to GNSS) | 6 | 6 | +| T-GM in holdover, out of holdover specification, traceable to Category 1 frequency source (Note 1) | 140 | 7 | +| T-GM in holdover, out of holdover specification, traceable to Category 2 frequency source (Note 1) | 150 | (Note 2) | +| T-GM in holdover, out of holdover specification, traceable to Category 3 frequency source (Note 1) | 160 | 52 | +| T-BC in holdover, out of holdover specification, using unspecified frequency source (Note 1) | 165 | 187 | + +**Table 5 – clockClass values for equipment deployed prior to this Recommendation** + +| | | | +|--------------------------------------------------------------------------------------------------------------------------------|-----|-----| +| Slave only OC (does not send Announce messages) | 255 | 255 | +| NOTE 1 – Initially after advertising clockClass values greater than 6, a clock may still be within the holdover specification. | | | +| NOTE 2 – Refer to the applicable value specified for the equipment. | | | +| NOTE 3 – The term "holdover" in this table refers to "time holdover". | | | + +# **7 ITU-T PTP profile for phase/time distribution with full timing support from the network** + +The PTP profile for phase/time distribution with full timing support from the network is contained in Annex A. + +# **8 Security aspects** + +For further study. + +## Annex A + +## ITU-T PTP profile for phase/time distribution with full timing support from the network + +(This annex forms an integral part of this Recommendation.) + +This annex contains the PTP telecom profile for phase/time distribution with full timing support from the network, as required by [IEEE 1588]. In order to claim compliance with this PTP telecom profile, the requirements in this annex and in the body of this Recommendation must both be met. + +### A.1 Profile identification + +profileName: ITU-T PTP profile for phase/time distribution with full timing support from the network + +profileVersion: 2.4 (for an implementation based on IEEE Std 1588-2008 [IEEE 1588-2008]) + +profileVersion: 2.5 (for an implementation based on IEEE Std 1588-2019 [IEEE 1588-2019]) + +profileIdentifier: 00-19-A7-01-02-04 (for an implementation based on IEEE Std 1588-2008 [IEEE 1588-2008]) + +profileIdentifier: 00-19-A7-01-02-05 (for an implementation based on IEEE Std 1588-2019 [IEEE 1588-2019]) + +See clause A.11 for details of compatibility between profile versions. + +This profile is specified by ITU-T. + +A copy may be obtained from [www.itu.int](http://www.itu.int). + +### A.2 PTP attribute values + +The default values and ranges of the PTP attributes for use in this profile are contained in Tables A.1, A.2, A.3, A.4, A.5, A.6 and A.7. For the attributes clockClass, clockAccuracy, offsetScaledLogVariance, and priority2, the ranges shown are those for the defaultDS. + +NOTE 1 – A boundary clock follows the rules of [IEEE 1588] for selection of parent clock, updating of parentDS, and transmission of Announce messages, so it may transmit values different from the defaultDS values. + +Attributes not specified by this profile must use the default initialization values and ranges defined in [IEEE 1588]. + +These tables provide a default initialization value and range for each data set member for: + +- Telecom grandmaster: ordinary clock or boundary clock that can only act as a GM (T-GM according to [ITU-T G.8275] – first PTP clock of the chain); +- Telecom time slave clock: ordinary clock with a clockClass = 255 (T-TSC according to [ITU-T G.8275] – last PTP clock of the chain); +- Telecom boundary clock: boundary clock that may or may not be a GM; such a clock will be a GM if it is the best clock in the network (T-BC according to [ITU-T G.8275] – intermediate PTP clocks of the chain); +- Telecom transparent clock: end-to-end transparent clock (T-TC according to [ITU-T G.8275] – intermediate PTP clock of the chain). + +The mapping between these PTP clockTypes and the phase/time clocks defined in the [ITU-T G.8275] architecture is described in Table 1, clause 6.2.3. + +The attributes defined in Tables A.6 and A.7 are only required for implementations based on [IEEE 1588-2008]; they have been deprecated in [IEEE 1588-2019]. For implementations based on [IEEE 1588-2008], these transparent clock datasets are not used for telecom grandmasters, telecom time slave clocks and telecom boundary clocks. For implementations based on [IEEE 1588-2008], they are mandatory for telecom transparent clocks. For implementations based on [IEEE 1588-2019], these transparent clock datasets are optional. + +NOTE 2 – A feature that is deprecated by [IEEE 1588], is no longer recommended or required. + +Some attributes in these tables are associated with optional features of this Recommendation. Therefore, these attributes are also optional, unless the associated feature is implemented, in which case these attributes must be supported. + +Unless explicitly documented within these tables, the data type of a dataset member is as per PTP. + +**Table A.1 – defaultDS data set member specifications** + +| [IEEE 1588-2008] | | [IEEE 1588-2019] | | Members of the data set | Telecom grandmaster requirements | | Telecom time slave clock requirements | | Telecom boundary clock requirements | | +|------------------|--------------|------------------|--------------|-----------------------------------------------------------|---------------------------------------|---------------------------------|---------------------------------------|---------------|---------------------------------------|-----------------| +| Clause | Data type | Clause | Data type | | Default initialization value (Note 5) | Range | Default initialization value (Note 5) | Range | Default initialization value (Note 5) | Range | +| 8.2.1.2.1 | As per PTP | (Note 3) | (Note 3) | defaultDS.twoStepFlag (static) | As per PTP | {FALSE, TRUE} | As per PTP | {FALSE, TRUE} | As per PTP | {FALSE, TRUE} | +| 8.2.1.2.2 | As per PTP | 8.2.1.2.2 | As per PTP | defaultDS.clock Identity (static) (Note 2) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.1.2.3 | As per PTP | 8.2.1.2.3 | As per PTP | defaultDS.numberPorts (dynamic) (Note 2) | 1 for OC
As per PTP for BC | {1} for OC
As per PTP for BC | 1 | {1} | As per PTP | As per PTP | +| 8.2.1.3.1.1 | As per PTP | 8.2.1.3.1.2 | As per PTP | defaultDS.clock Quality.clockClass (dynamic) | 248 | {6, 7, 140, 150, 160, 248} | 255 | {255} | 248 | {135, 165, 248} | +| 8.2.1.3.1.2 | As per PTP | 8.2.1.3.1.3 | As per PTP | defaultDS.clock Quality.clockAccuracy (dynamic) | 0xFE | As per PTP (Note 1) | 0xFE | {0xFE} | 0xFE | {0xFE} | +| 8.2.1.3.1.3 | As per PTP | 8.2.1.3.1.4 | As per PTP | defaultDS.clock Quality.offsetScaledLogVariance (dynamic) | 0xFFFF | As per PTP (Note 1) | 0xFFFF | {0xFFFF} | 0xFFFF | {0xFFFF} | +| 8.2.1.4.1 | As per PTP | 8.2.1.4.1 | As per PTP | defaultDS.priority1 (configurable) | 128 | {128} | 128 | {128} | 128 | {128} | +| 8.2.1.4.2 | As per PTP | 8.2.1.4.2 | As per PTP | defaultDS.priority2 (configurable) | 128 | {0-255} | 255 | {255} | 128 | {0-255} | +| 8.2.1.4.3 | As per PTP | 8.2.1.4.3 | As per PTP | defaultDS.domain Number (configurable) (Note 2) | 24 | {24-43} | 24 | {24-43} | 24 | {24-43} | +| 8.2.1.4.4 | As per PTP | 8.2.1.4.4 | As per PTP | defaultDS.slave Only (configurable) | FALSE | {FALSE} | TRUE | {TRUE} | FALSE | {FALSE} | +| (Note 4) | As per PTP | 8.2.1.4.5 | As per PTP | defaultDS.sdoId (configurable) (Note 2) | 0x000 | 0x000 | 0x000 | 0x000 | 0x000 | 0x000 | +| New member | UInteger8 | New member | UInteger8 | defaultDS.local Priority (configurable) | 128 | {1-255} | 128 | {1-255} | 128 | {1-255} | +| New member | UInteger8 | 8.2.1.5.4 | As per PTP | defaultDS.maxStepsRemoved (configurable) | 255 | {2-255} | 255 | {2-255} | 255 | {2-255} | +| New member | Enumeration8 | New member | Enumeration8 | defaultDS.deviceType (configurable) | (Note 6) | (Note 6) | (Note 6) | (Note 6) | (Note 6) | (Note 6) | +| New member | Octet[6] | New member | Octet[6] | defaultDS.profileIdentifier (configurable) | (Note 7) | (Note 7) | (Note 7) | (Note 7) | (Note 7) | (Note 7) | + +**Table A.1 – defaultDS data set member specifications** + +| | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NOTE 1 – Examples of applicable values are shown in clause 6.3.5. Additional values, not specified in clause 6.3.5, may be applicable to future use cases. These additional values are for further study. | +| NOTE 2 – Applicable also to T-TC in case of an [IEEE 1588-2019] based implementation. | +| NOTE 3 – In case of [IEEE 1588-2019] based implementations this data set member is deprecated. | +| NOTE 4 – Applicable to [IEEE 1588-2019] based implementations; this data set member does not exist in [IEEE 1588-2008]. | +| NOTE 5 – If a default value is not provided by this Recommendation, then it is implementation specific. | +| NOTE 6 – This attribute can be used to set the deviceType in use in the PTP clock instance. See clause 6.2.3.1 for more information and applicable values. | +| NOTE 7 – This dataset member is set according to the profileIdentifier specified in clause A.1 | + +**Table A.2 – currentDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Clause from [IEEE 1588-2019] | Members of the data set | Telecom grandmaster requirements | | Telecom time slave clock requirements | | Telecom boundary clock requirements | | +|------------------------------|------------------------------|--------------------------------------|---------------------------------------|------------|---------------------------------------|------------|---------------------------------------|------------| +| | | | Default initialization value (Note 3) | Range | Default initialization value (Note 3) | Range | Default initialization value (Note 3) | Range | +| 8.2.2.2 | 8.2.2.2 | currentDS.stepsRemoved (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.2.3 | 8.2.2.3 | currentDS.offsetFromMaster (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.2.4 | (Note 1) | currentDS.meanPathDelay (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| (Note 2) | 8.2.2.4 | currentDS.meanDelay (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | + +| | +|-------------------------------------------------------------------------------------------------------------------------| +| NOTE 1 – In case of [IEEE 1588-2019] based implementations this data set member is deprecated. | +| NOTE 2 – Applicable to [IEEE 1588-2019] based implementations; this data set member does not exist in [IEEE 1588-2008]. | +| NOTE 3 – If a default value is not provided by this Recommendation, then it is implementation specific. | + +**Table A.3 – parentDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Clause from [IEEE 1588-2019] | Members of the data set | Telecom grandmaster requirements | | Telecom time slave clock requirements | | Telecom boundary clock requirements | | +|------------------------------|------------------------------|----------------------------------------------------------|---------------------------------------|------------|---------------------------------------|------------|---------------------------------------|------------| +| | | | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | +| 8.2.3.2 | 8.2.3.2 | parentDS.parentPortIdentity (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.3.3 | 8.2.3.3 | parentDS.parentStats (dynamic) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | +| 8.2.3.4 | 8.2.3.4 | parentDS.observedParentOffsetScaledLogVariance (dynamic) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | + +**Table A.3 – parentDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Clause from [IEEE 1588-2019] | Members of the data set | Telecom grandmaster requirements | | Telecom time slave clock requirements | | Telecom boundary clock requirements | | +|------------------------------|------------------------------|-------------------------------------------------------|---------------------------------------|------------|---------------------------------------|------------|---------------------------------------|------------| +| | | | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | +| 8.2.3.5 | 8.2.3.5 | parentDS.observedParentClockPhaseChangeRate (dynamic) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note) | (Note 1) | +| 8.2.3.6 | 8.2.3.6 | parentDS.grandmasterIdentity (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.3.7 | 8.2.3.7 | parentDS.grandmasterClockQuality (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.3.8 | 8.2.3.8 | parentDS.grandmasterPriority1 (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.3.9 | 8.2.3.9 | parentDS.grandmasterPriority2 (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | + +NOTE 1 – It is not used in this profile, and therefore equipment is not required to support it. +NOTE 2 – If a default value is not provided by this Recommendation, then it is implementation specific. + +**Table A.4 – timePropertiesDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Clause from [IEEE 1588-2019] | Members of the data set | Telecom grandmaster requirements | | Telecom time slave clock requirements | | Telecom boundary clock requirements | | +|------------------------------|------------------------------|--------------------------------------------------|---------------------------------------|---------------|---------------------------------------|---------------|---------------------------------------|---------------| +| | | | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | +| 8.2.4.2 | 8.2.4.2 | timePropertiesDS.currentUtcOffset (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.4.3 | 8.2.4.3 | timePropertiesDS.currentUtcOffsetValid (dynamic) | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | +| 8.2.4.4 | 8.2.4.4 | timePropertiesDS.leap59 (dynamic) | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | +| 8.2.4.5 | 8.2.4.5 | timePropertiesDS.leap61 (dynamic) | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | +| 8.2.4.6 | 8.2.4.6 | timePropertiesDS.timeTraceable (dynamic) | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | FALSE | {FALSE, TRUE} | + +**Table A.4 – timePropertiesDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Clause from [IEEE 1588-2019] | Members of the data set | Telecom grandmaster requirements | | Telecom time slave clock requirements | | Telecom boundary clock requirements | | +|------------------------------|------------------------------|-----------------------------------------------|---------------------------------------|------------------------|---------------------------------------|------------------------|---------------------------------------|------------------------| +| | | | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | Default initialization value (Note 2) | Range | +| 8.2.4.7 | 8.2.4.7 | timePropertiesDS.frequencyTraceable (dynamic) | FALSE | {FALSE, TRUE} (Note 1) | FALSE | {FALSE, TRUE} (Note 1) | FALSE | {FALSE, TRUE} (Note 1) | +| 8.2.4.8 | 8.2.4.8 | timePropertiesDS.ptpTimescale (dynamic) | TRUE | {TRUE} | TRUE | {TRUE} | TRUE | {TRUE} | +| 8.2.4.9 | 8.2.4.9 | timePropertiesDS.timeSource (dynamic) | 0xA0 | As per PTP | 0xA0 | As per PTP | 0xA0 | As per PTP | + +NOTE 1 – Refer to clause 6.4 for details on when each value applies. +NOTE 2 – If a default value is not provided by this Recommendation, then it is implementation specific. + +**Table A.5 – portDS data set member specifications** + +| [IEEE 1588-2008] | | [IEEE 1588-2019] | | Members of the data set | Master port requirements of telecom grandmaster | | Slave port requirements of telecom time slave clock | | Telecom boundary clock requirements | | +|------------------|------------|------------------|------------|-----------------------------------------------------|-------------------------------------------------|---------------------------------|-----------------------------------------------------|------------|---------------------------------------|------------| +| Clause | Data type | Clause | Data type | | Default initialization value (Note 7) | Range | Default initialization value (Note 7) | Range | Default initialization value (Note 7) | Range | +| 8.2.5.2.1 | As per PTP | 8.2.15.2.1 | As per PTP | portDS.portIdentity.clockIdentity (static) (Note 3) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.5.2.1 | As per PTP | 8.2.15.2.1 | As per PTP | portDS.portIdentity.portNumber (static) (Note 3) | 1 for OC
As per PTP for BC | {1} for OC
As per PTP for BC | 1 | {1} | As per PTP | As per PTP | +| 8.2.5.3.1 | As per PTP | 8.2.15.3.1 | As per PTP | portDS.portState (dynamic) | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | As per PTP | +| 8.2.5.3.2 | As per PTP | 8.2.15.3.2 | As per PTP | portDS.logMinDelayReqInterval (dynamic) (Note 3) | -4 | {-4} | -4 | {-4} | -4 | {-4} | + +**Table A.5 – portDS data set member specifications** + +| [IEEE 1588-2008] | | [IEEE 1588-2019] | | Members of the data set | Master port requirements of telecom grandmaster | | Slave port requirements of telecom time slave clock | | Telecom boundary clock requirements | | +|------------------|------------|------------------|------------|---------------------------------------------------|-------------------------------------------------|---------------------|-----------------------------------------------------|---------------------|---------------------------------------|---------------------| +| Clause | Data type | Clause | Data type | | Default initialization value (Note 7) | Range | Default initialization value (Note 7) | Range | Default initialization value (Note 7) | Range | +| 8.2.5.3.3 | As per PTP | (Note 4) | (Note 4) | portDS.peerMeanPathDelay (dynamic) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | +| (Note 5) | (Note 5) | 8.2.15.3.3 | As per PTP | portDS.meanLinkDelay | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | +| 8.2.5.4.1 | As per PTP | 8.2.15.4.1 | As per PTP | portDS.logAnnounceInterval (configurable) | -3 | {-3} | -3 (Note 2) | {-3} (Note 2) | -3 | {-3} | +| 8.2.5.4.2 | As per PTP | 8.2.15.4.2 | As per PTP | portDS.announceReceiptTimeout (configurable) | 3 | {3 - z}
z is FFS | 3 | {3 - z}
z is FFS | 3 | {3 - z}
z is FFS | +| 8.2.5.4.3 | As per PTP | 8.2.15.4.3 | As per PTP | portDS.logSyncInterval (configurable) | -4 | {-4} | -4 (Note 2) | {-4} (Note 2) | -4 | {-4} | +| 8.2.5.4.4 | As per PTP | 8.2.15.4.4 | As per PTP | portDS.delayMechanism (configurable) | 01 | {01} | 01 | {01} | 01 | {01} | +| 8.2.5.4.5 | As per PTP | 8.2.15.4.5 | As per PTP | portDS.logMinPdelayReqInterval (configurable) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | (Note 1) | +| 8.2.5.4.6 | As per PTP | 8.2.15.4.6 | As per PTP | portDS.versionNumber (configurable) | 2 | {2} | 2 | {2} | 2 | {2} | +| (Note 5) | (Note 5) | 8.2.15.4.7 | As per PTP | portDS.minorVersionNumber (configurable) (Note 3) | 1 | {1} | 1 | {1} | 1 | {1} | +| (Note 5) | (Note 5) | 8.2.15.4.8 | As per PTP | portDS.delayAsymmetry (configurable) (Note 3) | NA | NA | As per PTP | As per PTP | As per PTP | As per PTP | +| New member | Boolean | 9.2.2.2 | As per PTP | portDS.masterOnly (configurable) (Note 6) | TRUE | {TRUE, FALSE} | FALSE | {FALSE} | TRUE | {TRUE, FALSE} | +| New member | UInteger8 | New member | UInteger8 | portDS.localPriority (configurable) | 128 | {1-255} | 128 | {1-255} | 128 | {1-255} | +| New member | UInteger16 | New member | UInteger16 | portDS.syncReceiptTimeout (configurable) | NA | NA | FFS | FFS | FFS | FFS | + +**Table A.5 – portDS data set member specifications** + +| [IEEE 1588-2008] | | [IEEE 1588-2019] | | Members of the data set | Master port requirements of telecom grandmaster | | Slave port requirements of telecom time slave clock | | Telecom boundary clock requirements | | +|------------------|------------|------------------|------------|-----------------------------------------------|-------------------------------------------------|---------------|-----------------------------------------------------|---------------|---------------------------------------|---------------| +| Clause | Data type | Clause | Data type | | Default initialization value (Note 7) | Range | Default initialization value (Note 7) | Range | Default initialization value (Note 7) | Range | +| New member | UInteger16 | New member | UInteger16 | portDS.delayRespReceiptTimeout (configurable) | NA | NA | FFS | FFS | FFS | FFS | +| New member | Boolean | New member | Boolean | portDS.SF (dynamic) | FALSE | {FALSE} | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | +| New member | Boolean | New member | Boolean | portDS.notMaster (configurable) (Note 6) | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | +| New member | Boolean | New member | Boolean | portDS.monitorSender (configurable) | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | +| New member | Boolean | New member | Boolean | portDS.monitorReceiver (configurable) | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | FALSE | {TRUE, FALSE} | + +NOTE 1 – It is not used in this profile, and therefore equipment is not required to support it. +NOTE 2 – This type of message is not sent by a slave-only OC. +NOTE 3 – Applicable also to T-TC in case of an [IEEE 1588-2019] based implementation. +NOTE 4 – In case of [IEEE 1588-2019] based implementations this data set member is deprecated. +NOTE 5 – Applicable to [IEEE 1588-2019] based implementations; this data set member does not exist in [IEEE 1588-2008]. +NOTE 6 – Setting both portDS.masterOnly and portDS.notMaster with value TRUE concurrently is not permitted. +NOTE 7 – If a default value is not provided by this Recommendation, then it is implementation specific. + +**Table A.6 – transparentClockDefaultDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Members of the data set | Telecom transparent clock requirements | | +|------------------------------|---------------------------------------------------------|----------------------------------------|-------------------| +| | | Default initialization value (Note) | Range | +| 8.3.2.2.1 | transparentClockDefaultDS.clockIdentity (static) | As per PTP | As per PTP | +| 8.3.2.2.2 | transparentClockDefaultDS.numberPorts (dynamic) | As per PTP for TC | As per PTP for TC | +| 8.3.2.3.1 | transparentClockDefaultDS.delayMechanism (configurable) | 01 | {01} | +| 8.3.2.3.2 | transparentClockDefaultDS.primaryDomain (configurable) | 24 | {24-43} | + +NOTE – If a default value is not provided by this Recommendation, then it is implementation specific. + +NOTE – According to [IEEE 1588-2019], the transparent clock data set members used in [IEEE 1588-2008] are deprecated. The relevant dataset members of a PTP instance should apply instead (see Tables A.1 and A.5). + +**Table A.7 – transparentClockPortDS data set member specifications** + +| Clause from [IEEE 1588-2008] | Members of the data set | Telecom transparent clock requirements | | +|------------------------------|----------------------------------------------------------|----------------------------------------|---------------| +| | | Default initialization value (Note 2) | Range | +| 8.3.3.2.1 | transparentClockPortDS.portIdentity (static) | As per PTP | As per PTP | +| 8.3.3.3.1 | transparentClockPortDS.logMinPdelayReqInterval (dynamic) | (Note 1) | (Note 1) | +| 8.3.3.3.2 | transparentClockPortDS.faultyFlag (dynamic) | FALSE | {FALSE, TRUE} | +| 8.3.3.3.3 | transparentClockPortDS.peerMeanPathDelay (dynamic) | (Note 1) | (Note 1) | + +NOTE 1 – It is not used in this profile, and therefore equipment is not required to support it. +NOTE 2 – If a default value is not provided by this Recommendation, then it is implementation specific + +NOTE – According to [IEEE 1588-2019], the transparent clock data set members used in [IEEE 1588-2008] are deprecated. The relevant dataset members of a PTP instance should apply instead (see Tables A.1 and A.5). + +### A.3 PTP options + +#### A.3.1 Node types required, permitted, or prohibited + +In this profile, the permitted node types are: ordinary clocks, boundary clocks and end-to-end transparent clocks. + +In this profile, the prohibited node types are: peer-to-peer transparent clocks. + +#### A.3.2 One-step versus two-step clock mode + +Both one-step and two-step clocks are permitted. A clock must be capable of receiving and handling messages transmitted from both one-step and two-step clocks. A clock is not required to support both one-step and two-step mode for transmitting messages. + +#### A.3.3 Transport mechanisms required, permitted, or prohibited + +In this profile, the allowed transport mechanisms are: + +- a) IEEE 802.3/Ethernet, as per Annex F of [IEEE 1588-2008] or Annex E of [IEEE 1588-2019]; +- b) OTN via: (i) GFP-F encapsulation as per [ITU-T G.704], and insertion of the GFP-F frames into the OTUk OSMC as per clause 15.7.2.4 of [ITU-T G.709] or into the FlexO OSMC as per clause 9.2.10.1 of [ITU-T G.709.1], or (ii) the OSC OSMC as per clause 14.1 of [ITU-T G.709], where in this case the encapsulation is vendor-specific; +- c) MTN, with PTP in Ethernet frames transported per clause 9.2.5 of [ITU-T G.832]; +- d) FlexE links, with PTP in Ethernet frames transported per clause 7.3.5 of [OIF FlexE IA]. + +At least one of the four transport mechanisms must be supported. For transport over IEEE 802.3/Ethernet, both the non-forwardable multicast address, 01-80-C2-00-00-0E, and the forwardable multicast address, 01-1B-19-00-00-00, are required to be supported for compliance with this profile. + +All other transport mechanisms are for further study within the scope of this profile. + +#### A.3.4 Unicast messages + +All messages are sent multicast, using one of the two multicast addresses in clause A.3.3. The unicast mode is not permitted in this version of the profile. + +### **A.4 Best master clock algorithm options** + +This profile uses the Alternate BMCA described in clause 6.3. + +### **A.5 Path delay measurement option (delay request/delay response)** + +The delay request/delay response mechanism is used in this profile. The peer delay mechanism must not be used in this profile. + +### **A.6 Clock identity format** + +For implementations based on [IEEE 1588-2008], the procedures to use an EUI-48 to create the EUI-64 clockIdentity as described in clause 7.5.2.2.2 of [IEEE 1588-2008] are no longer recommended. If a clockIdentity is formed by mapping an EUI-48 to an EUI-64, and if the EUI-48 was assigned from an MA-M or MA-S, it is possible that the clockIdentity will be a duplicate of a clockIdentity formed directly from a different MA-M or MA-S (i.e., by appending bits to the end of that different MA-M or MA-S). Only if the EUI-48 was formed from an OUI (MA-L), is the uniqueness ensured. For new implementations based on [IEEE 1588-2019], the clockIdentity shall be constructed as per clause 7.5.2.2.2 of [IEEE 1588-2019]. Non-IEEE clockIdentity formats are not supported. + +For implementations based on [IEEE 1588-2019], the clockIdentity shall be constructed as per clause 7.5.2.2.2 of [IEEE 1588-2019]. + +### **A.7 Configuration management options** + +Management aspects are for further study and will be specified in a future version of this profile. + +### **A.8 Security aspects** + +Security aspects are for further study. + +### **A.9 Other optional features of IEEE 1588** + +Other optional features of [IEEE 1588] are not used in this version of the profile. + +For implementations based on [IEEE 1588-2008] these include unicast message negotiation (clause 16.1 of [IEEE 1588-2008]), alternate timescales (clause 16.3 of [IEEE 1588-2008]), grandmaster clusters (clause 17.3 of [IEEE 1588-2008]), unicast discovery (clause 17.5 of [IEEE 1588-2008]), acceptable master table (clause 17.6 of [IEEE 1588-2008]), and the experimental cumulative frequency scale factor offset (Annex L of [IEEE 1588-2008]). + +For implementations based on [IEEE 1588-2019] these include unicast message negotiation (clause 16.1 of [IEEE 1588-2019]), alternate timescale offsets (clause 16.3 of [IEEE 1588-2019]), grandmaster clusters (clause 17.2 of [IEEE 1588-2019]), unicast discovery (clause 17.4 of [IEEE 1588-2019]), acceptable master table (clause 17.5 of [IEEE 1588-2019]), and the Cumulative frequency transfer method for synchronizing clocks (clause 16.10 of [IEEE 1588-2019]). + +Some aspects of the optional feature of alternate master are used by optional Annexes G and K of this Recommendation. + +### **A.10 PTP common header flags** + +The PTP common header flag values, and whether or not each flag is used in this profile, are given in Table A.8. + +NOTE – Some of these flags are used only in certain PTP messages, and not in all the PTP messages, see [IEEE 1588-2008] clause 13.3.2.6 or [IEEE 1588-2019] clause 13.3.2.8. + +For implementations based on [IEEE 1588-2008] the following rule defined in [IEEE 1588-2008] clause 13.3.2.6, must be respected: "For message types where the bit is not defined in Table 20, the values shall be FALSE." + +For implementations based on [IEEE 1588-2019] the following rule defined in [IEEE 1588-2019] clause 13.3.2.8, must be respected: "For message types where the bit is not defined in Table 37, the values shall be FALSE." + +**Table A.8 – PTP flags** + +| Octet | Bit | Flag | Value to be sent | Behaviour for the receiving node | +|-------|-----|------------------------|---------------------|-------------------------------------| +| 0 | 0 | alternateMasterFlag | FALSE | As per PTP | +| 0 | 1 | twoStepFlag | As per PTP | Used | +| 0 | 2 | unicastFlag | FALSE | Flag is ignored | +| 0 | 5 | PTP profile Specific 1 | FALSE | Flag is ignored | +| 0 | 6 | PTP profile Specific 2 | FALSE | Flag is ignored | +| 0 | 7 | Reserved | FALSE | Reserved by PTP and flag is ignored | +| 1 | 0 | leap61 | As per PTP (Note 2) | Used | +| 1 | 1 | leap59 | As per PTP (Note 2) | Used | +| 1 | 2 | currentUtcOffsetValid | As per PTP (Note 3) | Used (Notes 3, 4, 5, 6) | +| 1 | 3 | ptpTimescale | TRUE | Used | +| 1 | 4 | timeTraceable | See Table 3 | Used | +| 1 | 5 | frequencyTraceable | See Table 3 | Used | +| 1 | 6 | (Note 1) | (Note 1) | (Note 1) | + +NOTE 1 – An additional flag "synchronizationUncertain" has been defined in Annex E; the use of the "synchronizationUncertain" flag is optional. + +NOTE 2 – When a clock is in holdover, within holdover specification, the PTP clock may continue to advertise the last known leap second event. If there was no pending leap second event, then the PTP clock continues to advertise FALSE for the pending leap second fields (leap59 and leap61). If there was a pending leap second event, the PTP clock may choose either to advertise FALSE for the pending leap second fields immediately or to continue to advertise the leap second event. In the latter instance the PTP clock would clear the leap59 and leap61 second event field(s) and adjust the UTC offset field at the appropriate time based on its local PTP time (i.e., the local PTP time's UTC timescale rolling over at UTC midnight) if the PTP clock is still in holdover, within holdover specification. When a clock is in holdover, out of holdover specifications, the PTP clock behaviour with respect to leap second event is implementation specific. It is recommended that the PTP clock continue to advertise any upcoming leap second event as appropriate. + +NOTE 3 – When a clock is in holdover, within holdover specification, the PTP clock may continue to advertise the last known UTC offset with UTC offset valid TRUE. If the last known UTC offset valid was FALSE, then the PTP clock continues to advertise FALSE. If the last known UTC offset valid was TRUE then the PTP clock may choose either to advertise UTC offset valid FALSE immediately (freezing the UTC offset value) or to continue to advertise the last known UTC offset with UTC offset valid TRUE. The UTC offset field may be updated as described in Note 2 above. When a clock is in holdover, out of holdover specifications, the PTP clock behaviour with respect to UTC offset is implementation specific. + +NOTE 4 – Usage of currentUtcOffset from an Announce message, which indicates currentUtcOffsetValid as FALSE, may lead to wrong UTC time calculation. + +NOTE 5 – The alternate ABMCA in this profile does not consider or use currentUtcOffsetValid or currentUtcOffset. + +**Table A.8 – PTP flags** + +NOTE 6 – The PTP clocks in this profile do not use currentUtcOffsetValid or currentUtcOffset for phase/time synchronization. + +### A.11 Profile version compatibility + +A specific profile version may have backward compatibility with earlier versions of this profile. Table A.9 lists which earlier versions are compatible with each version. Compatibility means that the nodes can operate in the same network provided optional features in a specific profile that are not present in the earlier version are not enabled. + +**Table A.9 – profileVersion compatibility** + +| profileVersion | Base IEEE version | Compatible with the earlier profileVersions | +|----------------|-------------------|---------------------------------------------| +| 2.5 | [IEEE 1588-2019] | 2.4, 2.3, 2.2, 2.1, 2.0,
1.0 (Note) | +| 2.4 | [IEEE 1588-2008] | 2.2, 2.1, 2.0,
1.0 (Note) | +| 2.3 | [IEEE 1588-2019] | 2.2, 2.1, 2.0,
1.0 (Note) | +| 2.2 | [IEEE 1588-2008] | 2.1, 2.0,
1.0 (Note) | +| 2.1 | [IEEE 1588-2008] | 2.0,
1.0 (Note) | +| 2.0 | [IEEE 1588-2008] | 1.0 (Note) | +| 1.0 | [IEEE 1588-2008] | | + +NOTE – Version 1 of this profile enforced a limited range on acceptable values for clockClass, clockAccuracy, offsetScaledLogVariance and, for the T-TSC, priority2. Reception of values outside of the acceptable range caused the Announce message to be discarded. Version 2.x of the profile supports the full range of these attributes as defined by PTP. In networks deploying ePRTC, which use new values of clockAccuracy and offsetScaledLogVariance that are outside of the version 1 range, all clocks need to use version 2.x of the profile. If no ePRTC are to be deployed in the network, then the network can operate with a mixture of version 1 and version 2.x clocks. + +## **Annex B** + +## **Options to establish the PTP topology with the Alternate BMCA** + +(This annex forms an integral part of this Recommendation.) + +Options to establish the PTP topology with the Alternate BMCA are described in Annex C of [ITU-T G.8275]. + +## **Annex C** + +## **Inclusion of an external phase/time input interface in a T-BC** + +(This annex forms an integral part of this Recommendation.) + +The model for inclusion of a unidirectional, external phase/time interface on a PTP clock is provided in Annex B of [ITU-T G.8275]. + +## Annex D + +## Path trace (optional) + +(This annex forms an integral part of this Recommendation.) + +In order to track the actual path of the PTP synchronization reference in the network, the Path trace option as per clause 16.2 in [IEEE 1588] can be optionally supported by the PTP clock compliant with this profile. + +This feature is optional; however, if it is supported it is necessary that it be supported as described below. + +As an example, this option can be used to support troubleshooting analysis in case of failures in the network. + +It should be possible to configure a PTP clock so that the Path trace type length value (TLV) is not further forwarded by that clock (e.g., this could be required at the network administration interfaces). + +NOTE 1 – There might be cases when not all PTP clocks in the network support the Path trace TLV. The expected behaviour is that in the case of an incoming Announce message carrying the Path trace TLV, this TLV is dropped by these nodes. + +NOTE 2 – T-TCs in the path could add their own clockIdentity in the Path trace TLV. + +## **Annex E** + +## **Synchronization uncertain indication (optional)** + +(This annex forms an integral part of this Recommendation.) + +The synchronization uncertain indication is described in Annex D of [ITU-T G.8275]. + +## Annex F + +## Use of stepsRemoved to limit reference chain (optional) + +(This annex forms an integral part of this Recommendation.) + +The parameter stepsRemoved is defined in [IEEE 1588] is used to indicate the distance between a clock and the grandmaster clock in the network. It was originally intended to be used as a helpful tool to detect cyclic paths that may occur in PTP systems. By default, it is required that a clock not qualify any Announce messages where the stepsRemoved field is equal to, or greater than, 255 in order to ensure that rogue frames are extinguished. + +This profile includes a default dataset member, maxStepsRemoved, that allows the operator to configure the value to less than 255. The value configured is typically the same in all clocks in the PTP domain. When configured, a clock would not qualify any Announce messages received where the stepsRemoved field in the ingress header matched or exceeded the maxStepsRemoved field. There would be two primary use cases for this configurability. + +First, referring to [ITU-T G.8271.1] and [ITU-T G.8275] analysis has been performed to show that up to 20 clocks may be traversed between the grandmaster and slave while maintaining the proper network performance. If the operator wanted to ensure the network performance limit was not exceeded, or that the chain length was not exceeded, the operator may configure the value smaller (such as 20 or 21). + +Second, if the operator does deploy PTP in a ring topology, the operator may configure the maxStepsRemoved parameter to a smaller value so that the clocks may more quickly identify rogue frames and take corrective action to extinguish them and update the topology. + +## Annex G + +## Monitoring alternate master time information provided by a peer PTP port (optional) + +(This annex forms an integral part of this Recommendation.) + +This annex is optional but, if implemented, it is necessary for the equipment to conform to the requirements contained herein. + +A PTP clock must synchronize only to a PTP port of its parent clock that is in the MASTER state. The synchronization must be received on, and only on, the port of the PTP clock that is in the SLAVE state. However, in some instances it may be desirable for a PTP port to monitor a peer PTP port in a non-traditional situation, where the local PTP port is not in the SLAVE state and/or the peer PTP port is not in the MASTER state. + +The monitoring is enabled through the use of the portDS.monitorSender and portDS.monitorReceiver. When portDS.monitorSender is TRUE, and the portDS.portState is not MASTER, the PTP port sends Announce, Sync, Follow\_Up and Delay\_Resp messages with the alternateMasterFlag set to TRUE. When portDS.monitorReceiver is TRUE, and the portDS.portState is not SLAVE, the PTP port sends Delay\_Req messages with alternateMasterFlag set to FALSE. These messages may allow a PTP port to acquire knowledge of the characteristics of the transmission path. Some examples of use cases where a PTP port may want to acquire knowledge of the characteristics of the transmission path are included in the next sub-clauses. + +The monitoring feature uses some of the functionality of alternate master (clause 17.4 of [IEEE 1588-2008], clause 17.3 of [IEEE 1588-2019]), limited to the ability to transmit and process PTP messages in the PTP port states as described above, with the alternateMasterFlag set as appropriate. + +The following table captures various combinations of Port A and Port B states showing when Port A is able to monitor Port B. Some combinations may occur due to the use of masterOnly, notMaster, slaveOnly or some other means to override the default behaviour. + +**Table G.1 – Combination of PTP port states with monitoring** + +| Port A State | Port B State | Port A monitoring of Port B is supported when | | +|--------------|--------------|------------------------------------------------|----------------------------------------------| +| | | Port A configuration of portDS.monitorReceiver | Port B configuration of portDS.monitorSender | +| SLAVE | MASTER | (NOTE 1) | (NOTE 2) | +| PASSIVE | MASTER | TRUE | (NOTE 2) | +| MASTER | SLAVE | TRUE | TRUE | +| MASTER | PASSIVE | TRUE | TRUE | +| MASTER | MASTER | TRUE | (NOTE 2) | + +NOTE 1 – The configuration of portDS.monitorReceiver does not impact the operation of a PTP port in the SLAVE state (i.e., is not required to be TRUE). +NOTE 2 – The configuration of portDS.monitorSender does not impact the operation on a PTP port in the MASTER state (i.e., is not required to be TRUE). + +NOTE – Table G.1 lists the most typical combinations of PTP port states. The monitoring function described in this annex also applies to other combinations. + +### G.1 Use case 1 – PASSIVE port monitoring MASTER port + +Figure G.1 shows an example to illustrate where a PTP clock with a PTP port in the PASSIVE state (portDS.monitorReceiver is TRUE) monitors a peer PTP port in the MASTER state. As shown below, T-BC #4 has a PTP port in the PASSIVE state and it is desirable to monitor T-BC #2 that has a PTP port in the MASTER state. When the T-BC #4 PTP PASSIVE port receives the Sync and Delay\_Resp message from the T-BC #2 PTP MASTER port, the T-BC #4 can get the time error based on PTP timestamps. If the difference of the time error of PASSIVE port and the time error of SLAVE port exceeds a threshold, this PTP clock may generate an alarm, which means that a fibre asymmetric, or a clock failure could be present in this PTP network. Note this alarm is just used for PTP monitoring and should not trigger the BMCA. Additionally, the threshold used for this alarm should be properly configured to avoid inappropriate alarms. + +![Diagram illustrating Use case 1: PASSIVE port monitoring MASTER port. A PTP network (MASTER) is connected to T-BC #1. T-BC #1 has Port 1 (SLAVE), Port 3 (MASTER), and Port 4 (MASTER). Port 4 (MASTER) is connected to T-BC #2. T-BC #2 has Port 2 (SLAVE) and Port 3 (MASTER). Port 3 (MASTER) is connected to T-BC #3. T-BC #3 has Port 1 (SLAVE) and Port 4 (MASTER). Port 4 (MASTER) is connected to T-BC #4. T-BC #4 has Port 1 (PASSIVE) and Port 2 (SLAVE). A dashed arrow indicates monitoring from T-BC #4 Port 1 (PASSIVE) to T-BC #2 Port 3 (MASTER).](60ffbad6c0fb7371a57fe8f267d2d141_img.jpg) + +The diagram shows a hierarchy of PTP clocks. At the top is a cloud labeled 'PTP network (MASTER)'. Below it is T-BC #1, which has three ports: Port 1 (SLAVE), Port 3 (MASTER), and Port 4 (MASTER). Port 4 (MASTER) is connected to T-BC #2. T-BC #2 has two ports: Port 2 (SLAVE) and Port 3 (MASTER). Port 3 (MASTER) is connected to T-BC #3. T-BC #3 has two ports: Port 1 (SLAVE) and Port 4 (MASTER). Port 4 (MASTER) is connected to T-BC #4. T-BC #4 has two ports: Port 1 (PASSIVE) and Port 2 (SLAVE). A dashed arrow points from T-BC #4 Port 1 (PASSIVE) to T-BC #2 Port 3 (MASTER), indicating the monitoring path. The text 'G.8275.1-Y.1369.1(22)\_FG.1' is at the bottom right. + +Diagram illustrating Use case 1: PASSIVE port monitoring MASTER port. A PTP network (MASTER) is connected to T-BC #1. T-BC #1 has Port 1 (SLAVE), Port 3 (MASTER), and Port 4 (MASTER). Port 4 (MASTER) is connected to T-BC #2. T-BC #2 has Port 2 (SLAVE) and Port 3 (MASTER). Port 3 (MASTER) is connected to T-BC #3. T-BC #3 has Port 1 (SLAVE) and Port 4 (MASTER). Port 4 (MASTER) is connected to T-BC #4. T-BC #4 has Port 1 (PASSIVE) and Port 2 (SLAVE). A dashed arrow indicates monitoring from T-BC #4 Port 1 (PASSIVE) to T-BC #2 Port 3 (MASTER). + +Figure G.1 – PASSIVE port monitors MASTER port + +### G.2 Use case 2 – MASTER port monitoring PASSIVE port + +Figure G.2 shows an example to illustrate where a PTP clock with a PTP port in the MASTER state (portDS.monitorReceiver is TRUE) monitors a peer PTP port in the PASSIVE state (portDS.monitorSender is TRUE). In the situation shown, Port 2 could be a PTP port or a virtual PTP port in the SLAVE state preferring to synchronize to the local GNSS receiver. Port 1 in the MASTER state is used for monitoring of the PTP network, and through the monitoring function, the PTP clock is able to measure the time error on the PTP network. + +Note that in Figure G.2 it is assumed that the PTP Clock Port 1 is in the MASTER state and the peer port in the PTP network is in the PASSIVE state, but that the opposite may also occur (where Port 1 is PASSIVE and the peer port in the PTP Network is MASTER, which is described in clause G.1) depending on the network planning and the BMCA. + +![Diagram of a PTP clock with Port 1 (MASTER) connected to a passive PTP network and Port 2 (SLAVE) connected to a PRTC.](0a42e05c07941450f34e4f7117725834_img.jpg) + +The diagram shows a rectangular box labeled "PTP clock" at the bottom. Inside the box, there are two ports: "Port 1 (MASTER)" on the left and "Port 2 (SLAVE)" on the right. Above Port 1, an arrow points up to a cloud labeled "PTP network (PASSIVE)". Above Port 2, an arrow points down from a rectangle labeled "PRTC". Below the ports, the text "PTP clock" is written. At the bottom right of the diagram, the text "G.827.5.1-Y.1369.1(22)\_FG.2" is present. + +Diagram of a PTP clock with Port 1 (MASTER) connected to a passive PTP network and Port 2 (SLAVE) connected to a PRTC. + +**Figure G.2 – MASTER port monitors PASSIVE port** + +### G.3 Use Case 3 – MASTER port monitoring MASTER port + +Figure G.3 shows a use case where a PTP probe may monitor information from a PTP clock. Additionally, the PTP clock may likewise monitor information from the PTP probe. Considering a PTP probe working as a monitor function instead of a PTP reference, it is assumed that the PTP clock Port 2 is configured with portDS.masterOnly TRUE in order to prevent the PTP probe from being selected by the BMCA of the PTP clock. To allow the PTP probe to monitor the PTP clock, the port of the PTP probe is configured with portDS.monitorReceiver TRUE. To allow the PTP clock to monitor the PTP probe, Port 2 of PTP clock is configured with portDS.monitorReceiver TRUE. Once both are configured as described there may be a full exchange of information between the PTP probe and the PTP clock. As a result, the PTP probe may full characterize/probe the PTP clock (receiving Sync & Delay\_Resp), but also the PTP clock may gain the full knowledge of the PTP probe, by reception of Sync & Delay\_Resp from the PTP probe. + +Note, for some use cases, it may be only necessary to monitor the timing of one direction but not both, e.g., a PTP probe monitors a PTP clock, or a PTP clock monitors a PTP probe to estimate its accuracy. + +![Diagram of a PTP clock with Port 1 (SLAVE) connected to a master PTP network and Port 2 (MASTER) connected to a master PTP probe.](b44f89b176c971c7dd264c07bfef2c2a_img.jpg) + +The diagram shows a rectangular box labeled "PTP clock" at the bottom. Inside the box, there are two ports: "Port 1 (SLAVE)" on the left and "Port 2 (MASTER)" on the right. Above Port 1, an arrow points down from a cloud labeled "PTP network (MASTER)". Above Port 2, an arrow points down from a rectangle labeled "PTP probe (MASTER)". Below the ports, the text "PTP clock" is written. At the bottom right of the diagram, the text "G.827.5.1-Y.1369.1(22)\_FG.3" is present. + +Diagram of a PTP clock with Port 1 (SLAVE) connected to a master PTP network and Port 2 (MASTER) connected to a master PTP probe. + +**Figure G.3 – MASTER port monitors MASTER port** + +## Annex H + +## Transport of PTP over OTN + +(This annex forms an integral part of this Recommendation.) + +The transport of PTP over OTN shall be performed by encapsulating the PTP messages into GFP-F frames as specified in clause 7.10 of [ITU-T G.704], and then inserting the GFP-F frames into the OTUk OSMC as specified in clause 15.7.2.4 of [ITU-T G.709] and the FlexO OSMC as specified in clause 9.2.10 of [ITU-T G.709.1]. + +The PTP messages shall be timestamped as specified in clause 15.7.2.4.1 of [ITU-T G.709] and in clause 9.2.10.1 of [ITU-T G.709.1]. + +PTP messages may also be carried over the OSC OSMC as specified in clause 14.1 of [ITU-T G.709]. The PTP encapsulation in this latter case is vendor specific. + +All bits of the transportSpecific field (see clause 13.3.2.1 of (IEEE 1588-2008)) shall be transmitted as zero and shall be ignored by the receiver. + +The value of the networkProtocol enumeration for the transport of PTP over OTN shall be F000 (hex). + +## **Annex I** + +## **Transport PTP over MTN** + +(This annex forms an integral part of this Recommendation.) + +The transport of PTP over MTN is performed by encapsulating PTP messages into Ethernet frames that are transported by the MTN overhead per Clause 9.2.5 of [ITU-T G.8312]. The PTP event messages are timestamped. The timestamp generation is for further study. + +The value of the networkProtocol enumeration for the transport of PTP over MTN is F001 (hex). + +## **Annex J** + +## **Transport PTP over FlexE links** + +(This annex forms an integral part of this Recommendation.) + +The transport of PTP over FlexE shall be performed by encapsulating PTP messages into Ethernet frames that are transported by the FlexE overhead per clause 7.3.5 of [OIF FlexE IA]. The PTP event messages shall be timestamped as per clause 7.3.5 of [OIF FlexE IA]. + +The value of the networkProtocol enumeration for the transport of PTP over FlexE shall be F002 (hex). + +## Annex K + +## Dynamic Monitoring based on PTSF (Optional) + +(This annex forms an integral part of this Recommendation.) + +This annex is optional but, if implemented, it is necessary for the equipment to conform to the requirements contained herein. + +This annex describes an approach to dynamic monitoring of a neighbour PTP port by a PTP port with local PTSF. When this annex is implemented, a PTP port is additionally permitted to transmit Delay\_Req messages and process received Delay\_Resp messages irrespective of the PTP port state based on the PTSF status, as described below. The PTSF function is specified by clause 6.3.9. + +When a PTSF event has occurred at a PTP port of a PTP clock, the PTP clock may set portDS.SF to TRUE according to clause 6.3.9. Upon the change of portDS.SF to TRUE, even if the PTP port state is not in the SLAVE state, the PTP port is allowed to send Delay\_Req message and receive Delay\_Resp messages. This functionality allows the local PTP port to update the PTSF status. If it is verified that the PTSF has cleared, portDS.SF of the PTP port is set to FALSE. As a result, the PTP port is considered as a candidate reference with normal handling of PTP messages. + +The monitoring feature uses some of the functionality of alternate master (clause 17.4 of [IEEE 1588-2008], clause 17.3 of [IEEE 1588-2019]), limited to the ability to transmit and processes PTP messages in the PTP port states as described above, with the alternateMasterFlag set as appropriate. + +An example for the case of T-BC is shown by Figure K.1. + +![Diagram illustrating an example of PTSF restoration. T-BC #1 (bottom) has Port 1 (MASTER) and Port 2 (SLAVE). Port 1 is connected to Port 1 (MASTER) of T-BC #2 (top left) and Port 1 (MASTER) of T-BC #3 (top right). The diagram shows Port 1 of T-BC #1 in the MASTER state, indicating restoration after a failure.](5c3dd31372f59e15250f0ab1613ca485_img.jpg) + +The diagram shows three Time Boundary Clocks (T-BCs): T-BC #1, T-BC #2, and T-BC #3. T-BC #1 is at the bottom and contains two ports: Port 1 (MASTER) and Port 2 (SLAVE). T-BC #2 is at the top left and contains Port 1 (MASTER). T-BC #3 is at the top right and contains Port 1 (MASTER). Arrows indicate connections from Port 1 of T-BC #2 and Port 1 of T-BC #3 to Port 1 of T-BC #1. A label 'G.8275.1-Y.1369.1(22)\_FK.1' is located at the bottom right of the diagram. + +Diagram illustrating an example of PTSF restoration. T-BC #1 (bottom) has Port 1 (MASTER) and Port 2 (SLAVE). Port 1 is connected to Port 1 (MASTER) of T-BC #2 (top left) and Port 1 (MASTER) of T-BC #3 (top right). The diagram shows Port 1 of T-BC #1 in the MASTER state, indicating restoration after a failure. + +Figure K.1 – An example of PTSF restoration + +In Figure K.1, Port 1 of T-BC #1 was previously in the SLAVE state synchronizing with Port 1 of T-BC #2. After a while, T-BC #1 detects a PTSF event at Port 1 and changes its portDS.SF to TRUE. According to clause 6.3.9, T-BC #1 runs its alternate BMCA, selects Port 1 of T-BC #3 as its new reference, and sets Port 2 to SLAVE, Port 1 to MASTER. + +In order to recover the PTSF failure of Port 1 of T-BC #1, that T-BC needs to continue to send messages towards T-BC#2 to detect when the SF condition is resolved. The event of portDS.SF with TRUE triggers Port 1 of T-BC #1 to continue to send Delay\_Req messages. Port 1 of T-BC #2 in MASTER is able to reply with Delay\_Resp messages. As a result, Port 1 of T-BC #1 will continue to receive Announce, Sync and Delay\_Resp messages in order to determine if the signal fail condition has been cleared. If the failure is cleared, T-BC #1 puts portDS.SF of Port 1 to FALSE and then Announce messages received on Port 1 of T-BC #1 can be considered in the alternate BMCA. + +## Appendix I + +### Considerations on the use of transparent clock + +(This appendix does not form an integral part of this Recommendation.) + +The integration of the transparent clock in this profile is considered of particular interest for applications such as 2-port type of devices. + +For more complex topologies and multiport devices some careful analysis is recommended. In particular, some specific node configuration may be required if the operator wants to prevent multicast packets flooding the network. + +Some options could be considered, e.g., by configuration of the T-TCs with insertion of a VLAN tag in the frames carrying PTP. In this case all T-TCs in the PTP communication path where this option is used should support this option. The last T-TC node would need to remove the VLAN tag. By using this option to connect the physical ports of the T-GM, T-BC, and T-TSCs through VLAN virtual connections across the T-TCs, the multicast flooding can be avoided. In this way the PTP port of a T-GM, T-BC or T-TSC would never process a VLAN tagged frame. + +The related operational implications would need to be carefully considered. + +## Appendix II + +### Considerations on the transmission of Delay\_Req messages + +(This appendix does not form an integral part of this Recommendation.) + +This appendix discusses the requirements defined in [IEEE 1588] for the transmission of *Delay\_Req* messages when using the default uniform distribution defined in bullet 3 of clause 9.5.11.2 of [IEEE 1588-2008] and bullet (1) of clause 9.5.11.2 of [IEEE 1588-2019]. This uniform distribution is not used in the PTP telecom profile defined in this Recommendation; a profile-specific distribution has been defined in clause 6.2.8. + +The second dashed item of the requirements defined in clause 9.5.11.2 of [IEEE 1588-2008] and bullet (b) of clause 9.5.11.2 of [IEEE 1588-2019] controls the variability of the times between successive *Delay\_Req* messages. It is analogous to the corresponding requirement for the sending of *Sync* and *Announce* messages, given in clause 7.7.2.1 of [IEEE 1588]. However, a key difference is that, while the requirement for *Sync* messages applies to the population of inter-message intervals, the requirement for *Delay\_Req* messages applies only to the mean of the population. + +To be more precise, assume that a population of $N$ inter-message intervals has been measured, and let $T_j$ be the measured values, $j = 1, 2, \dots, N$ . The sample mean, $m$ , is just the numerical average, i.e., + +$$m = \frac{1}{N} \sum_{j=1}^N T_j \quad (\text{II.1})$$ + +Let $T_{min}$ be the minimum *Delay Request* interval; it is equal to $2^{\text{portDS.logMinDelayReqInterval}}$ s. The second dashed item above states that the mean of the distribution must be greater than or equal to $T_{min}$ with 90% or greater statistical confidence. + +The statistical test for this is well-known and is based on the fact that the distribution of $m$ approaches a normal distribution as $N$ becomes large (i.e., it is based on the central limit theorem). Let $\sigma$ be the standard deviation of the distribution of the inter-message times, i.e., the distribution of the $T_j$ . Let $z_{0.90}$ be the 90th percentile of the standard normal distribution; it is given by $z_{0.90} = 1.281$ . Then, the probability that the true mean of the distribution exceeds the quantity + +$$q_{0.1} = m - z_{0.90} \sqrt{\frac{\sigma}{N}} \quad (\text{II.2})$$ + +is 0.9, i.e., 90%. The probability that the mean of the distribution is less than this value is 0.1. In addition, if $\sigma$ is not known, the sample standard deviation, $s$ , may be used in equation (II.2) and the Normal distribution is replaced by the Student- $t$ distribution with $N - 1$ degrees of freedom. The sample standard deviation is given by: + +$$s = \left[ \frac{1}{N-1} \sum_{j=1}^N (T_j - m)^2 \right]^{1/2} \quad (\text{II.3})$$ + +To meet the requirement, the quantity $q_{0.1}$ must exceed $T_{min}$ . It is seen from equation (II.2) that $q_{0.1}$ approaches $m$ as $N$ approaches infinity. Since $m$ converges to the mean of the distribution of inter-message times as $N$ approaches infinity, the requirement can be met for sufficiently large $N$ as long as the mean of the distribution exceeds $T_{min}$ . The mean of the distribution must exceed $T_{min}$ ; the requirement cannot be met if the mean of the distribution is exactly equal to $T_{min}$ or less than $T_{min}$ . + +If it is chosen to comply with the requirement of the third dashed item of clause 9.5.11.2 of [IEEE 1588-2008] or bullet (1) of clause 9.5.11.2 of [IEEE 1588-2019], one way of meeting this + +requirement is to increase the upper end of the probability distribution by 10%. If this is done, the transmission times are selected such that the interval between successive *Delay\_Req* messages is taken from a uniform distribution over the interval between 0 and $2.2T_{min}$ . A new random value for the transmission interval is computed for each message transmitted. When computing the mean *Delay\_Req* interval from measured samples to check if it exceeds $T_{min}$ with 90% or greater statistical confidence (if the third dashed item is used), the number of measured samples $N$ must be at least 1000. The granularity of the distribution must be less than or equal to 1/16 *Sync* interval. + +If it is chosen to meet the requirement of the fourth dashed item of clause 9.5.11.2 of [IEEE 1588] or bullet (2) of clause 9.5.11.2 of [IEEE 1588-2019], a *Delay\_Req* message is transmitted as soon as possible after receipt of a *Sync* message, subject to not violating the second dashed item. + +## Appendix III + +### Considerations on the choice of the PTP Ethernet multicast destination address + +(This appendix does not form an integral part of this Recommendation.) + +This PTP profile supports both the non-forwardable multicast address 01-80-C2-00-00-0E and forwardable multicast address 01-1B-19-00-00-00 when the PTP mapping defined in Annex F of [IEEE 1588-2008] or Annex E of [IEEE 1588-2019] is used. + +The Ethernet multicast address to be used depends on the operator policy; further considerations are provided hereafter. + +Layer 2 bridging function associated with the PTP port of a T-BC or T-TC should not forward any frame with destination MAC address 01-1B-19-00-00-00; this could be done by properly provisioning this multicast address in the filtering database. + +#### Option 1 – Use of the non-forwardable multicast address 01-80-C2-00-00-0E + +Some network operators consider that the PTP messages must never be forwarded through PTP-unaware network equipment. + +The use of the non-forwardable multicast address 01-80-C2-00-00-0E guarantees this property most of the time (exceptions exist for some older Ethernet equipment). + +Therefore, in the case of network equipment misconfiguration (e.g., if the PTP functions are not enabled in PTP-aware network equipment), the use of this multicast address prevents incorrect distribution of synchronization, since the PTP messages will be blocked by the PTP-unaware network equipment. + +#### Option 2 – Use of the forwardable multicast address 01-1B-19-00-00-00 + +Some network operators consider that using a forwardable multicast address is more flexible and that it is preferable to forward the PTP messages to keep the synchronization link running in case some equipment is misconfigured as non PTP nodes, although there are potentially risks of performance degradation. The network management system (NMS) will easily find the misconfiguration and will send alarms. + +However, it is possible to block the PTP messages by properly provisioning this multicast address in the filtering database of each Ethernet equipment. + +## Appendix IV + +### Considerations on the use of priority2 + +(This appendix does not form an integral part of this Recommendation.) + +The PTP attribute priority2 is configurable in this profile. In some special circumstances, the use of the priority2 attribute can simplify the network management. This appendix describes two use cases; other possible cases are for further study. + +#### Case 1 + +Operators can configure the PTP attribute priority2 to make all of the T-BCs either traceable to one T-GM, or traceable to two different T-GMs at the same time. + +![Diagram illustrating the use of priority2 with two T-GMs in the network. Two T-GMs (orange circles) are shown at the top. The left T-GM is connected to a T-BC (EEC) (orange circle) via a red square. The right T-GM is connected to another T-BC (EEC) (orange circle) via a red square. The two T-BCs (EECs) are connected to each other via a dashed line, with red squares on the connections. The diagram is labeled G.8275.1-Y.1369.1(14)_FIV.1.](21327313f7b18a481da0c87a6472a80d_img.jpg) + +G.8275.1-Y.1369.1(14)\_FIV.1 + +Diagram illustrating the use of priority2 with two T-GMs in the network. Two T-GMs (orange circles) are shown at the top. The left T-GM is connected to a T-BC (EEC) (orange circle) via a red square. The right T-GM is connected to another T-BC (EEC) (orange circle) via a red square. The two T-BCs (EECs) are connected to each other via a dashed line, with red squares on the connections. The diagram is labeled G.8275.1-Y.1369.1(14)\_FIV.1. + +Figure IV.1 – Use of priority2 with two T-GMs in the network + +For example, in Figure IV.1, if all other PTP attributes of the two T-GMs are the same, and the two T-GMs are configured with the same priority2 value, each T-BC will select the T-GM with the shortest path. If the two T-GMs are configured with different priority2 values, all of the T-BCs will synchronize to the T-GM with the smallest priority2 value. + +#### Case 2 + +Operators can configure the PTP attribute priority2 to prevent the T-BCs of an upstream network from synchronizing with the T-BCs of a downstream network when the T-GM is in failure. + +![Diagram illustrating the use of priority2 with T-BCs of different network layers. A T-GM (orange circle) is connected to a T-BC (EEC) (orange circle) via a red square. This T-BC is part of an 'Upstream network' (oval) containing three T-BCs (EECs) (orange circles) connected in a chain. The last T-BC in the upstream network is connected to a T-BC (EEC) (orange circle) via a red square. This T-BC is part of a 'Downstream network' (oval) containing three T-BCs (EECs) (orange circles) connected in a chain. The last T-BC in the downstream network is connected to a T-TSC (EEC) (orange circle) via a red square. The diagram is labeled G.8275.1-Y.1369.1(14)_FIV.2.](daf05db9f13b34fb12da52f007bbfe5b_img.jpg) + +G.8275.1-Y.1369.1(14)\_FIV.2 + +Diagram illustrating the use of priority2 with T-BCs of different network layers. A T-GM (orange circle) is connected to a T-BC (EEC) (orange circle) via a red square. This T-BC is part of an 'Upstream network' (oval) containing three T-BCs (EECs) (orange circles) connected in a chain. The last T-BC in the upstream network is connected to a T-BC (EEC) (orange circle) via a red square. This T-BC is part of a 'Downstream network' (oval) containing three T-BCs (EECs) (orange circles) connected in a chain. The last T-BC in the downstream network is connected to a T-TSC (EEC) (orange circle) via a red square. The diagram is labeled G.8275.1-Y.1369.1(14)\_FIV.2. + +Figure IV.2 – Use of priority2 with T-BCs of different network layers + +For example, in Figure IV.2, if all other PTP attributes of all of the T-BCs are the same, and the PTP attribute priority2 of all of T-BCs are configured with the same value, then when the T-GM is in failure, the T-BCs in the upstream network can synchronize with the T-BCs in the downstream network, depending on the clockIdentity values of all of the T-BCs. If the T-BCs in the upstream network are configured with a smaller priority2 value than the T-BCs in the downstream network then, when the T-GM is in failure, the T-BCs in the downstream network will synchronize to the T-BCs in the upstream network. + +## Appendix V + +### **Description of PTP clock modes and associated contents of Announce messages** + +(This appendix does not form an integral part of this Recommendation.) + +Description of PTP clock modes and associated contents of Announce messages are described in Appendix VIII of [ITU-T G.8275]. + +## Appendix VI + +### Operations over link aggregation + +(This appendix does not form an integral part of this Recommendation.) + +When two devices embedding PTP clocks compliant with this profile are connected via a link aggregation (LAG) as defined in [b-IEEE 802.1AX], each physical link should be accessed directly to transmit PTP messages, bypassing the LAG. This method prevents potential asymmetries that may be present when the forward and reverse paths are delivered over different links belonging to the LAG. + +Alternative solutions taking advantage of some LAG features exist, such as the bidirectional congruity as defined by [b-IEEE 802.1AX]. For the scenarios currently considered, the insertion of a VLAN tag in the frames carrying PTP messages is not allowed. However, the bidirectional congruity alternative solution can be applied to untagged PTP frames by assigning a conversation ID equal to zero to a given physical link. These solutions are for further study. + +## Appendix VII + +### Relationship between clockClass and holdover specification + +(This appendix does not form an integral part of this Recommendation.) + +The clockClass values that are used in this profile are described in Table 3. The values may be divided into four different categories: + +- 1) T-GM locked to a PRTC or ePRTC; +- 2) T-GM or T-BC in holdover, within holdover specification; +- 3) T-GM or T-BC in holdover, outside of holdover specification; +- 4) Slave clock, or clock that has not been synchronized. + +A short footnote (Note 1 of clause 6.4) refers to Appendix V of [ITU-T G.8271.1] for more information on the meaning of "in holdover, within holdover specification" and "in holdover, out of holdover specification". That appendix describes possible budget models for the synchronization performance. The exact model depends on the operator's network and design parameters, but each budget is broken down into several components: + +- 1) PRTC/T-GM allocation; +- 2) Random time error from noise accumulation through the network (dTE); +- 3) Node asymmetry (cTE, the sum of the asymmetry of all the nodes in the system); +- 4) Link asymmetry (cTE, the sum of the asymmetry of all the links in the system); +- 5) Holdover budget; +- 6) End application budget. + +Table V.1 of [ITU-T G.8271.1] shows that for one example budget, 400 ns may be allocated to holdover within the network (this is termed failure scenario (b) in the table). The operator may have different budget allocations, depending on their deployment scenario. The 400 ns holdover budget is allocated to the entire synchronization chain, and not to an individual clock. + +The intended operation of the T-GM is, therefore, as follows: + +- When the T-GM is synchronised to a PRTC locked to GNSS, it outputs clockClass 6. +- If the PRTC loses its connection to GNSS, it enters holdover. The T-GM should degrade the advertised clockClass to indicate "in holdover, but within holdover specification" (clockClass 7). +- The T-GM estimates when the holdover budget will potentially be exceeded. Factors to consider include the known quality of any external frequency support (e.g., SyncE QL), temperature variations, and/or the quality of the internal oscillator. +- When the T-GM considers that the clock is out of holdover specification (i.e., it is now estimated to have drifted by more than the holdover budget), the T-GM will advertise a clockClass of 140, 150 or 160. + +In the event of a network failure, where the T-GM is disconnected from the synchronization chain, a T-BC will take over as the grandmaster of the chain. That T-BC will be operating in holdover. The clockClass that the T-BC is allowed to advertise depends on the clockClass of the T-GM to which it was synchronized prior to losing connectivity. + +For example, if the T-BC was synchronized to a T-GM of clockClass 6, none of the holdover budget will have been consumed, and therefore the T-BC may use a clockClass indicating "within holdover specification" (e.g., clockClass 135). This value is chosen to be higher than that of a T-GM that is out of holdover specification, since the T-BC is likely to have more accurate time because it has been locked to a traceable time source more recently. Therefore, if the two clocks (a T-BC in holdover, + +within holdover specification and a T-GM in holdover, but out of holdover specification) are compared in the Alternate BMCA operation of a subsequent clock, the subsequent clock will synchronize to the T-BC that is within holdover specification instead of a T-GM that is out of holdover specification. + +In another example, if the T-BC was synchronized to a T-GM indicating that the T-GM is in holdover but out of holdover specification (e.g., parentDS clockClass 140, 150 or 160), the T-BC should also use a clockClass indicating "out of holdover specification" (e.g., defaultDS clockClass 165). This is because the T-GM was indicating that, in its estimation, the holdover budget has already been consumed. + +In another example, if the T-BC was synchronized to another T-BC, and the other T-BC indicates that it is in holdover but out of holdover specification (e.g., parentDS clockClass 165), the original T-BC should also use a clockClass indicating "out of holdover specification" (e.g., defaultDS clockClass 165). This is because the other T-BC was indicating that, in its estimation, the holdover budget has already been consumed. + +In a final example, if the T-BC was synchronized to a T-GM or another T-BC that was already in holdover but still within the holdover specification, the original T-BC could indicate "within holdover specification". However, some of the holdover budget will have already been consumed by the T-GM or T-BC. If it is not known how much of the budget is left, the T-BC should indicate "out of holdover specification". + +NOTE 1 – When the term clockClass is used with respect to the property of the individual PTP clock (T-GM, T-BC, T-TSC) it is referring to data set member defaultDS.clockQuality.clockClass. + +NOTE 2 – If a T-BC was synchronized to a T-GM or to another T-BC that was in free-run mode (advertising clockClass 248), the T-BC should continue to advertise clockClass 248 even after it loses its reference. + +## Appendix VIII + +### Considerations on a T-TSC connected to an end application + +(This appendix does not form an integral part of this Recommendation.) + +The default T-TSC clockclass 255 implies that the T-TSC will always lock to an external PTP reference when available. + +The actual synchronization source ultimately used by the end application depends on the applicable synchronization needs. This process is out of the scope of this Recommendation. + +As an example, the decision to use the PTP reference that has been selected by the T-TSC (e.g., instead of entering holdover), could depend on the actual clockQuality, frequencyTraceable flag, timeTraceable flag, and synchronizationUncertain flag associated to the external PTP reference. Additional aspects as related to performance monitoring of the external reference might also be considered. This is implementation specific. + +As an example, when it is required to meet the network timing requirements as per e.g., [ITU-T G.8271.1], it would be necessary that the external PTP reference has clockClass 6, 7 or 135 and that the timeTraceable flag is TRUE in order to be used by the end application. When this condition is not met, the end application may decide to enter holdover (either using the internal oscillator or driven by SyncE). + +NOTE – The specific behaviour for a T-TSC embedded in the end application is outside the scope of this Recommendation. It is assumed that interoperability with the profile is maintained. + +## Appendix IX + +### Calculation of offsetScaledLogVariance for T-GM timed by PRTC or ePRTC + +(This appendix does not form an integral part of this Recommendation.) + +### IX.1 Observation interval and TDEV noise generation + +The offsetScaledLogVariance is an offset, scaled representation of the PTP variance (PTPVAR). PTPVAR is described in clause 7.6.3 of [IEEE 1588]; it is equal to Allan variance multiplied by $\tau^2/3$ , where $\tau$ is the observation interval. PTP variance is therefore not a single value; it is a function of observation interval. Clause 7.6.3 of [IEEE 1588] specifies that the observation interval $\tau$ shall be the value defined in the applicable PTP profile. Clause 7.6.3 of [IEEE 1588] refers to $\tau$ as the sampling period. However, comparison of the equations in clause 7.6.3.2 of [IEEE 1588] with the equations for Allan variance in clause II.1 of [ITU-T G.810] indicates that $\tau$ in clause 7.6.3 of [IEEE 1588] is the observation interval of [ITU-T G.810], and not the sampling interval $\tau_0$ . + +The offsetScaledLogVariance, i.e., defaultDS.clockQuality.offsetScaledLogVariance, is a clock attribute used in the BMCA. As indicated in clause 7.6.3.5 of [IEEE 1588], it is "an estimate of the variations of the local clock from a linear timescale when it is not synchronized to another clock using the protocol" (quoted text is from [IEEE 1588]; the "protocol" refers to the PTP protocol). Since a clock is not synchronized to another clock via PTP when it is grandmaster, the offsetScaledLogVariance should represent the long-term noise that the clock generates, because it is this noise that is generated if the clock is grandmaster. Therefore, the observation interval should be the longest interval over which noise generation for the clock in question is specified. + +For a T-GM timed by a PRTC, i.e., a clock that meets the requirements of [ITU-T G.8272], the longest observation interval for which noise generation TDEV is specified is 10000 s (see Figure 2 of [ITU-T G.8272]). For this interval, TDEV is 30 ns. The specified noise type for intervals ranging from 1000 s to 10000 s is flicker phase modulation (FPM), with TDEV equal to 30 ns in this range. For a T-GM timed by an ePRTC, the longest observation interval for which noise generation TDEV is specified is $10^6$ s. For this interval, TDEV is 10 ns. The specified noise type for intervals ranging from $3 \times 10^5$ s to $10^6$ s is FPM, with TDEV equal to 10 ns in this range. + +The value of the observation interval is not used directly in the PTP protocol and is not carried in any PTP messages. It is used only in evaluating PTP variance. + +The above values of observation interval and corresponding noise generation TDEV, for the PRTC and ePRTC, are summarized in Table IX.1. + +**Table IX.1 – Observation intervals, and corresponding noise generation TDEV values and noise type, for T-GM timed by PRTC and T-GM timed by ePRTC** + +| Clock that T-GM is timed by | Observation interval ( $\tau$ ) for offsetScaledLogVariance (s) | $n = \tau / \tau_0$ (see clause IX.2 below) | Noise type | TDEV (ns) | +|-----------------------------|-----------------------------------------------------------------|---------------------------------------------|------------|-----------| +| PRTC | 1000 – 10000 | $1.6 \times 10^4$ to $1.6 \times 10^5$ | FPM | 30 | +| ePRTC | 300 000 – 1 000 000 | $4.8 \times 10^6$ to $1.6 \times 10^7$ | FPM | 10 | + +### IX.2 Computation of PTP variance from TDEV + +The next step is to compute PTP variance from the TDEV values given in the previous clause. Since PTP variance is equal to $\tau^2/3$ multiplied by Allan variance, and time variance (TVAR) is equal to $\tau^2/3$ multiplied by modified Allan variance, the ratio of TVAR to PTP variance is equal to the ratio of modified Allan variance (MVAR) to Allan variance. This latter ratio is discussed and computed for various noise types in section A.6 of [b-Sullivan]. The results given there are based on [b-Walls] and + +[b-Lesage]. In addition, the relations between power spectral density (PSD) and Allan variance are given in Table 5.4 of [b-Bregni], and between PSD and modified Allan variance in Table 5.5 of [b-Bregni] (when using relations between PSD and various time-domain stability parameters, it is important to take note of whether the PSD is of time ( $S_x(f)$ ) or of frequency ( $S_y(f)$ )). + +Let $n$ be the ratio of observation interval $\tau$ to sampling interval $\tau_0$ , i.e., $\tau = n\tau_0$ . In general, the ratio of MVAR to AVAR, denoted $R(n)$ , depends on $n$ , though at least for the noise types white phase modulation (WPM), flicker FPM, white frequency modulation (WFM), flicker frequency modulation (FFM), and random-walk frequency modulation (RWFM), it approaches an asymptotic value for large $n$ . In addition, for the case of FPM $R(n)$ depends on the measurement system bandwidth (for WPM, both AVAR and MVAR individually depend on measurement system bandwidth, though their ratio does not). Since time synchronization information from whichever clock is selected as grandmaster is transported via Sync messages, the sampling interval $\tau_0$ can be taken equal to the Sync interval. The actual successive Sync intervals vary with time, as allowed by clause 7.7.2.1 of [IEEE 1588]; for simplicity, we may take $\tau_0$ equal to the mean Sync interval. This is 1/16 s in [ITU-T G.8275.1]. Then, using the observation interval values in Table IX.1 above, the corresponding values of $n$ range from $1.6 \times 10^4$ to $1.6 \times 10^5$ for a T-GM timed by a PRTC, and from $4.8 \times 10^5$ to $1.6 \times 10^5$ for a T-GM timed by an ePRTC. The values of $n$ are also summarized in Table IX.1 above. + +From Table IX.1, it is seen that the range of $n$ is different for the PRTC and ePRTC. This means that, even though the noise type in the ranges of interest for these clocks is the same, $R(n)$ will be different, and TVAR for each clock will be adjusted by a different factor to obtain PTPVAR. However, the PRTC and ePRTC stability (as well as the stability of other clocks used in telecommunications) are specified using TDEV (i.e., square root of TVAR), and not using PTPDEV or PTPVAR. It therefore would be desirable to adjust TVAR for the PRTC and ePRTC by the same factor. In previous work, in which TVAR for the PRTC was compared to TVAR for a T-BC timed by SyncE, $R(n)$ was equal to 0.787. This value is used here for convenience, for both the PRTC and ePRTC. + +With the above assumption, PTPVAR for the PRTC is given by: + +$$\text{PTPVAR (PRTC)} = \frac{\text{TVAR}}{R(n)} = \frac{(30 \times 10^{-9})^2 \text{ s}^2}{0.787} = 1.144 \times 10^{-15} \text{ s}^2 \quad (\text{IX.1})$$ + +and PTPVAR for the ePRTC is given by: + +$$\text{PTPVAR (ePRTC)} = \frac{\text{TVAR}}{R(n)} = \frac{(10 \times 10^{-9})^2 \text{ s}^2}{0.787} = 1.271 \times 10^{-16} \text{ s}^2 \quad (\text{IX.2})$$ + +### IX.3 Computation of offsetScaledLogVariance from PTP variance + +offsetScaledLogVariance is now computed from the PTPVAR results of the previous clause, using the procedure described in clause 7.6.3.3 of [IEEE 1588]. This procedure is: + +- a) The logarithm to base 2 of PTPVAR expressed in units of $\text{s}^2$ is computed; +- b) The result of (a) is multiplied by $2^8$ to produce a scaled value; +- c) The scaled value is modified per the hysteresis specification of clause 7.6.3.3 of [IEEE 1588]. (This step is not needed here, because offsetScaledLogVariance is being computed from a specification, rather than from real-time measurements.); +- d) The result of (c) is represented as a 2s complement Integer16 (i.e., it is represented as a signed integer, where negative values are represented in 2s complement form (since PTPVAR is less than $1 \text{ s}^2$ in almost all cases of practical interest, and certainly in the cases described in the previous clause, the result of (c) will almost always be negative)); +- e) The value 0x8000 is added to the result of (d), and any overflow is ignored; + +- f) The result of (e) is cast as an Integer16. This result, which may also be expressed in writing in hexadecimal form, is offsetScaledLogVariance. + +#### IX.3.1 Computation of offsetScaledLogVariance for a T-GM timed by a PRTC + +From Eq. (IX.1), PTPVAR = $1.144 \times 10^{-15}$ s2. Using steps (a) – (f) above, we obtain + +$$\begin{aligned} \log_2(\text{PTPVAR}) &= \frac{\ln(1.144 \times 10^{-15})}{\ln 2} = -49.6348 \\ 2^8 \log_2(\text{PTPVAR}) &= \frac{(256) \ln(1.144 \times 10^{-15})}{\ln 2} = -12706.5176 @ 12707 \end{aligned} \quad (\text{IX.3})$$ + +Representing the above as a signed integer in 2s complement form produces + +$$12707 = 31A3_{16} \mapsto CE5C_{16} \text{ (1s complement form)} \mapsto CE5D_{16} \text{ (2s complement form)} \quad (\text{IX.4})$$ + +Adding $8000_{16}$ to the above and ignoring any overflow produces + +$$CE5D_{16} + 8000_{16} = 14E5D_{16} \mapsto 4E5D_{16} \quad (\text{IX.5})$$ + +The resulting offsetScaledLogVariance is $4E5D_{16}$ . + +#### IX.3.2 Computation of offsetScaledLogVariance for a T-GM timed by an ePRTC + +The logarithm to base 2 of PTPVAR expressed in units of s2 is computed and the result is multiplied by $2^8$ to produce a scaled value. + +$$\begin{aligned} \log_2(\text{PTPVAR}) &= \frac{\ln(1.271 \times 10^{-16})}{\ln 2} = -52.8049 \\ 2^8 \log_2(\text{PTPVAR}) &= \frac{(256) \ln(1.271 \times 10^{-16})}{\ln 2} = -13518.0507 \cong -13518 \end{aligned} \quad (\text{IX.6})$$ + +Representing the above as a signed integer in 2s complement form produces + +$$13518 = 34CE_{16} \Rightarrow CB31_{16} \text{ (1s complement form)} \Rightarrow CB32_{16} \text{ (2s complement form)} \quad (\text{IX.7})$$ + +Adding $8000_{16}$ to the above and ignoring any overflow produces + +$$CB32_{16} + 8000_{16} = 14B32_{16} \Rightarrow 4B32_{16} \quad (\text{IX.8})$$ + +The resulting offsetScaledLogVariance is $4B32_{16}$ . + +## Appendix X + +## Description of a T-BC extended clockClass application + +(This appendix does not form an integral part of this Recommendation.) + +Table 3 of [ITU-T G.8275.1] defines a T-BC extended clockClass application. This appendix describes the purpose of this extended application, and its corresponding value amendments, including defaultDS data set member specifications of Annex A of [ITU-T G.8275.1] (corresponding to Table A.1) and T-BC Announce message contents of Appendix V of [ITU-T G.8275.1] (corresponding to Table V.3). + +### X.1 Purpose of T-BC extended clockClass application + +PTP is the only synchronization source in an [IEEE 1588] network, therefore the clockClass values have been only applied to the PTP clock for indicating its inherent characteristics. The clockClass in Table 5 of the [IEEE 1588-2008] and Table 4 of [IEEE 1588-2019], such as 6,7,52,187, only represents the T-GM. The clockClass may not reflect the change of synchronization states in the T-BCs deployed in the network. + +Since it is possible that there are two separate synchronization sources (GNSS time and physical frequency) in a telecom network, an extension mechanism of the clockClass range to cover the case of both T-GM and T-BC changes is provided. The definition of the clockClass values is extended into two parts: + +- 1) for a T-GM, the range of clockClass includes 6, 7, 140, 150 and 160. The clockClass values of 140/150/160 represent the time output of T-GM when it is in time holdover instead of tracking to GNSS. The time quality is consistent with the clock quality of the frequency category 1, 2, and 3 respectively; +- 2) for a T-BC, the clockClass includes 135 and 165. The value of 135 means that when a T-BC is in time holdover, the output time signal is within specification, clockClass 165 means that the output time signal is out of time holdover specification. + +The case of two separated sources has been considered in [ITU-T G.8271.1] HRM-2 and HRM-3. In order to extend the advantages of two separated sources, it is better to treat a T-BC differently when it is traceable to frequency of a different quality. The clockClass of 165 could be assigned to a T-BC when the T-BC is traceable to a frequency in QL-SEC, and the T-BC could share the clockClass value of 140/150/160 with the T-GM when it is traceable to a different quality of frequency. In this way, the appropriate T-BC can be selected to be the GM of the network so that better time signals can be sent to the end-users. + +For a telecom network, it is crucial to make sure that the best clock selection principle is valid in any PTP network, especially in the case where there exists an isolated time region (which cannot receive any signals from the T-GM) in the network. In this region, if the T-BC has a preferred frequency quality, the T-BC can act as a T-GM and send out precise time/phase signals (where the signal quality is still close to UTC). In telecom networks, from the perspective of synchronization performance, any of the T-BCs could supersede the old T-GM to be the new PTP source of the network. + +### X.2 DefaultDS data set member specifications under this extended application + +In some cases, the values of clockClass/accuracy/variance will likely be the same as that delivered by the announce packets from the T-GM and T-BC per Table 3/Note 3. As such, the T-BC should synchronize the T-GM. It is suitable for priority 2 to achieve this goal, and the range of priority 2 should be divided into two parts, 0-127 for the T-GM, 128-255 for the T-BC. + +In this PTP profile, the clock attribute priority2 is configurable. + +If this feature is used, then the *priority2* for the T-GM should be set to a lower value compared to T-BCs, in particular the range for *priority2* could be allocated as follows: + +- for T-GM, the range {0-127}; +- for T-BC, the range {128-255}. + +As an example of a default value for *priority2*, it is suggested to set the T-GM to 100 and the T-BC to 128. + +## Appendix XI + +### Considerations on native access equipment + +(This appendix does not form an integral part of this Recommendation.) + +In some deployments, native access equipment such as xDSL, xPON, and microwave equipment may have implemented T-BC functionality. This appendix provides information on how such equipment may be modeled as a pair of T-BCs defined in this Recommendation. The following Figure XI.1 shows an example of equipment that is transferring the PTP timing between native PTP and native access media. Examples of such equipment may be an xPON OLT & ONU, an xDSL DSLAM & RT-DSLAM, or microwave equipment. Only one PTP port and one Special port are shown in the diagram, although the equipment may contain multiple ports. Within this simplified diagram there are two PTP ports on the T-BC; one is a normal PTP port and one is a Special PTP port. On both the PTP port and the Special PTP port, the Announce information and Signalling messages are handled according to normal T-BC operation. The difference is that on the PTP port, the timing messages (Sync, Delay\_Req, Delay\_Resp) are handled normally, while on the Special PTP port they are not present as they are replaced by native timing messages. If the timing flow hierarchy is known in advance (such as that of a PON OLT, which will only transfer timing downstream on its Special PTP ports) then the PTP ports, Special PTP ports, or the PTP clock may be configured with masterOnly or slaveOnly parameters (such as a PON OLT configured with Special PTP ports as masterOnly TRUE, or a PON ONU configured with slaveOnly TRUE). + +![Diagram illustrating the timing flow between native PTP and native access media. The diagram shows a central box representing the equipment, divided into two main sections: 'Native-access clock' and 'PTP clock', separated by a 'Native-access to PTP IWF' (Interworking Function). The 'Native-access clock' section contains a 'Special port (state: timing slave)'. The 'PTP clock' section contains a 'PTP port (state: timing master)'. Arrows indicate the flow of messages: 'Native timing transfer' (blue) between the top external port and the Special port; 'Announce info' (purple) and 'Signalling' (purple) between the top external port and the PTP port; 'Sync', 'Delay Req', and 'Delay Resp' (blue) between the bottom external port and the PTP port; and 'Announce' (purple) and 'Signalling' (purple) between the bottom external port and the PTP port. Dashed lines indicate that the top and bottom external ports 'May be one physical port'.](74b540f71bcf10a8a66b2f01ea8c08ec_img.jpg) + +Diagram illustrating the timing flow between native PTP and native access media. The diagram shows a central box representing the equipment, divided into two main sections: 'Native-access clock' and 'PTP clock', separated by a 'Native-access to PTP IWF' (Interworking Function). The 'Native-access clock' section contains a 'Special port (state: timing slave)'. The 'PTP clock' section contains a 'PTP port (state: timing master)'. Arrows indicate the flow of messages: 'Native timing transfer' (blue) between the top external port and the Special port; 'Announce info' (purple) and 'Signalling' (purple) between the top external port and the PTP port; 'Sync', 'Delay Req', and 'Delay Resp' (blue) between the bottom external port and the PTP port; and 'Announce' (purple) and 'Signalling' (purple) between the bottom external port and the PTP port. Dashed lines indicate that the top and bottom external ports 'May be one physical port'. + +G.8275.1-Y.1369.1(16)-Amd.1(17)\_FXI.1 + +**Figure XI.1 – Timing flow between native PTP and native access media** + +This appendix shows one possible way to model native access media (as a pair of T-BCs). Other ways to model native access media may exist. + +## **Appendix XII** + +### **Monitoring alternate master time information provided by a peer PTP port** + +(This appendix does not form an integral part of this Recommendation.) + +The contents of this appendix have been moved into Annex G. + +## **Appendix XIII** + +### **Considerations on the use of [IEEE 1588-2019]** + +(This appendix does not form an integral part of this Recommendation.) + +Considerations on the use of [IEEE 1588-2019] are discussed in Appendix IX of [ITU-T G.8275]. + +## Appendix XIV + +### Considerations in an environment of more than two PTP ports on a single PTP communication path when using transparent clocks and multicast addressing + +(This appendix does not form an integral part of this Recommendation.) + +There are some aspects of PTP topology that are unique to a multicast environment that uses transparent clocks. When the network is restricted to ordinary and boundary clocks, each transport layer connection has only two PTP ports. On an ordinary clock or boundary clock each local PTP port will only ever communicate with one external PTP port. When transparent clocks are introduced, this situation changes and one local PTP port may communicate with more than one external PTP port. + +In Figure XIV.1, PTP clocks A, B, and C are connected using a transparent clock. This makes the three PTP ports A.1, B.1, and C.1 endpoints of a single PTP communication path. Each of these ports shall have a portDS dataset within their respective clocks. + +In this example, it is assumed that PTP ports A.1 and B.1 either have masterOnly set to TRUE or, due to some transport layer distribution of Announce messages (not shown in Figure XIV.1) and/or the rules of the alternate BCMA of [ITU-T G.8275.1], both ports are in MASTER state. Both ports will transmit Announce messages advertising the quality of the grandmaster clocks they are using. Port C.1 will receive the Announce messages from ports A.1 and B.1 due to the transparent clock connection. + +According to [IEEE 1588], port C.1 may use a foreign master table and compute an Erbbest based on the data of these two flows of Announce messages. In this example, the grandmaster information from port A.1 is better than the grandmaster information from port B.1. The BMCA in clock C shall cause clock A to be the parent PTP instance, shall set parentDS.parentPortIdentity to be port A.1 and shall place port C.1 into SLAVE state. + +If there is a problem in the PTP communication between PTP port A.1 and PTP port C.1 then one of the events specified in clause 6.3.9 may be raised by clock C. These PTSF conditions may only apply to that PTP communication; there may be no such condition in the PTP communication between ports B.1 and C.1. Clock C should switch from using port A.1 to port B.1 as its source of timing. + +If the PTP communication between Port A.1 and Port C.1 has a PTSF event, the Port C.1 should select the data set associated with the Port B.1 as its Erbbest data set instead of setting portDS.SF to TRUE. However, if both PTP communications with the Port A.1 and Port B.1 have a PTSF event, the Port C.1 should set portDS.SF to TRUE. + +![Diagram showing three PTP ports (Port A.1 (M), Port B.1 (M), Port C.1) interconnected via a central T-TC (Transparent Clock) using multicast addressing. Clock A, Clock B, and Clock C are associated with the ports. The diagram includes a small text label: G.8275.1-Y.1369.1(20)-Amd.2(21)_FXIV.1.](6a7ea9d5162b0a0cfbd8d77c6cac90d1_img.jpg) + +The diagram illustrates a network topology for Precision Time Protocol (PTP) using multicast addressing. At the top, two boxes represent Clock A and Clock B. Clock A contains 'Port A.1 (M)' and Clock B contains 'Port B.1 (M)'. Below them is a central box labeled 'T-TC' (Transparent Clock). At the bottom is another box containing 'Port C.1' and 'Clock C'. Blue arrows indicate the flow of PTP messages: from Port A.1 to the T-TC, from Port B.1 to the T-TC, and from the T-TC to Port C.1. A dashed blue line connects the T-TC to Port C.1. Below the Port C.1 box is the text 'G.8275.1-Y.1369.1(20)-Amd.2(21)\_FXIV.1'. + +Diagram showing three PTP ports (Port A.1 (M), Port B.1 (M), Port C.1) interconnected via a central T-TC (Transparent Clock) using multicast addressing. Clock A, Clock B, and Clock C are associated with the ports. The diagram includes a small text label: G.8275.1-Y.1369.1(20)-Amd.2(21)\_FXIV.1. + +**Figure XIV.1 – Three PTP ports interconnected using a transparent clock with multicast addressing** + +## Appendix XV + +### Considerations of deploying ePRTC and PRTC in the network + +(This appendix does not form an integral part of this Recommendation.) + +In some deployment scenarios, both ePRTC and PRTC may be deployed in a same PTP network, e.g., an ePRTC in a central location in the network, and a PRTC closer to the end application. In this scenario, there could be several T-BCs between the ePRTC and the end application, and there will be PTP noise accumulation through the chain of T-BCs. Therefore, for the end application closer to a PRTC, it may be better to select the PRTC instead of an ePRTC due to the noise accumulation through the chain of T-BCs. + +To allow the current Alternate BMCA of this recommendation to choose a T-GM connected to a PRTC instead of an ePRTC in such deployment scenario as described above, operators may choose to use clock accuracy of 0x21 for the ePRTC instead of 0x20, and to use offsetScaledLogVariance of 0x4E5D for the ePRTC instead of 0x4B32. + +NOTE – There may be other solutions to address this case (e.g., an Alternate BMCA using an enhanced synchronization accuracy metrics TLV); they are for further study. + +# Bibliography + +- [b-IEEE 802.1AX] IEEE 802.1AX (2020), *IEEE Standard for Local and metropolitan area networks – Link Aggregation*. +- [b-Bregni] Stefano Bregni, (2002), *Synchronization of Digital Telecommunications Networks*, Wiley. +- [b-Lesage] Paul Lesage and Theophane Ayi (1984), *Characterization of Frequency Stability: Analysis of the Modified Allan Variance and Properties of Its Estimate*, IEEE Transactions on Instrumentation and Measurement, Vol. IM-33, No. 4 (included in [b-Sullivan] as paper D.6). +- [b-Sullivan] D.B. Sullivan, D.W. Allan, D.A. Howe, and F.L. Walls (1990), *Characterization of Clocks and Oscillators*, NIST Technical Note 1337. +- [b-Walls] F.L. Walls, John Gary, Abbie O'Gallagher, Roland Sweet, and Linda Sweet (1991), *Time Domain Frequency Stability Calculated from the Frequency Domain Description: Use of the SIGINT Software Package to Calculate Time Domain Frequency Stability from the Frequency Domain*, NIST Report NISTR 89-3916 Revised (revision of 1989 version of this report). + +# ITU-T Y-SERIES RECOMMENDATIONS + +## **GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES** + +### **GLOBAL INFORMATION INFRASTRUCTURE** + +| | | +|-------------------------------------------|-------------| +| General | Y.100–Y.199 | +| Services, applications and middleware | Y.200–Y.299 | +| Network aspects | Y.300–Y.399 | +| Interfaces and protocols | Y.400–Y.499 | +| Numbering, addressing and naming | Y.500–Y.599 | +| Operation, administration and maintenance | Y.600–Y.699 | +| Security | Y.700–Y.799 | +| Performances | Y.800–Y.899 | + +### **INTERNET PROTOCOL ASPECTS** + +| | | +|--------------------------------------------------------------------|----------------------| +| General | Y.1000–Y.1099 | +| Services and applications | Y.1100–Y.1199 | +| Architecture, access, network capabilities and resource management | Y.1200–Y.1299 | +| Transport | Y.1300–Y.1399 | +| Interworking | Y.1400–Y.1499 | +| Quality of service and network performance | Y.1500–Y.1599 | +| Signalling | Y.1600–Y.1699 | +| Operation, administration and maintenance | Y.1700–Y.1799 | +| Charging | Y.1800–Y.1899 | +| IPTV over NGN | Y.1900–Y.1999 | + +### **NEXT GENERATION NETWORKS** + +| | | +|-------------------------------------------------------------------|---------------| +| Frameworks and functional architecture models | Y.2000–Y.2099 | +| Quality of Service and performance | Y.2100–Y.2199 | +| Service aspects: Service capabilities and service architecture | Y.2200–Y.2249 | +| Service aspects: Interoperability of services and networks in NGN | Y.2250–Y.2299 | +| Enhancements to NGN | Y.2300–Y.2399 | +| Network management | Y.2400–Y.2499 | +| Computing power networks | Y.2500–Y.2599 | +| Packet-based Networks | Y.2600–Y.2699 | +| Security | Y.2700–Y.2799 | +| Generalized mobility | Y.2800–Y.2899 | +| Carrier grade open environment | Y.2900–Y.2999 | + +### **FUTURE NETWORKS** + +### **CLOUD COMPUTING** + +### **BIG DATA** + +### **QUANTUM KEY DISTRIBUTION NETWORKS** + +### **INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES** + +| | | +|---------------------------------------------------------|---------------| +| General | Y.4000–Y.4049 | +| Definitions and terminologies | Y.4050–Y.4099 | +| Requirements and use cases | Y.4100–Y.4249 | +| Infrastructure, connectivity and networks | Y.4250–Y.4399 | +| Frameworks, architectures and protocols | Y.4400–Y.4549 | +| Services, applications, computation and data processing | Y.4550–Y.4699 | +| Management, control and performance | Y.4700–Y.4799 | +| Identification and security | Y.4800–Y.4899 | +| Evaluation and assessment | Y.4900–Y.4999 | + +For further details, please refer to the list of ITU-T Recommendations. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and 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sha256:a792cdaacbaa45a842c32842c38c6d43eac797ad31f46262efa3951151c3661d +size 48867 diff --git a/marked/G/T-REC-G.828-200003-I_PDF-E/raw.md b/marked/G/T-REC-G.828-200003-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..5bbd1b834573d104f24fec8bc9ceff0ef018553f --- /dev/null +++ b/marked/G/T-REC-G.828-200003-I_PDF-E/raw.md @@ -0,0 +1,746 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.828** + +(03/2000) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – Quality +and availability targets + +--- + +**Error performance parameters and objectives +for international, constant bit rate synchronous +digital paths** + +ITU-T Recommendation G.828 + +(Formerly CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# **Error performance parameters and objectives for international, constant bit rate synchronous digital paths** + +## **Summary** + +This Recommendation defines error performance parameters and objectives for international synchronous digital paths. While this Recommendation specifically addresses objectives for international digital paths, the allocation principles can be applied to the design of error performance for national or private synchronous digital paths. The objectives given are independent of the physical network supporting the path. This Recommendation is based upon a block-based measurement concept using error detection codes inherent to the path under test; the block repetition rate being in accordance with SDH technology. This simplifies in-service measurements. The events, parameters and objectives are defined accordingly. In addition to path performance assessment, tandem connection monitoring is covered. + +It is not required to apply this Recommendation to SDH paths using equipment designed prior to the date of adoption of this version of ITU-T Recommendation G.828 (March 2000). + +## **Source** + +ITU-T Recommendation G.828 was prepared by ITU-T Study Group 13 (1997-2000) and approved under the WTSC Resolution 1 procedure on 10 March 2000. + +## **Keywords** + +Background Block Error (BBE), block-based concept, Error Detection Codes (EDC), error performance objectives, error performance parameters, Errored Second (ES), In-Service Measurements (ISM), Severely Errored Period (SEP), Severely Errored Second (SES), synchronous digital path, Tandem Connection Monitoring (TCM). + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2001 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | Page | +|-------------------------------------------------------------------------------------------------|-------------| +| 1 Scope..... | 1 | +| 1.1 Application of this Recommendation ..... | 1 | +| 1.2 Transport network layers ..... | 2 | +| 1.2.1 SDH transport networks ..... | 2 | +| 1.2.2 ATM connections ..... | 2 | +| 1.3 Allocation of end-to-end performance..... | 3 | +| 2 References..... | 3 | +| 3 Definitions and abbreviations ..... | 3 | +| 3.1 Abbreviations..... | 3 | +| 3.2 Terms and Definitions ..... | 5 | +| 3.2.4 Error performance events ..... | 5 | +| 3.2.5 Error performance parameters ..... | 5 | +| 3.2.6 Additional error performance event / performance parameter ..... | 6 | +| 4 Measurement of the block..... | 6 | +| 4.1 In-service monitoring..... | 6 | +| 4.2 Out-of-service measurements ..... | 6 | +| 5 Performance monitoring at the near end and far end of a path ..... | 6 | +| 6 Error performance objectives..... | 7 | +| 6.1 End-to-end objectives ..... | 7 | +| 6.2 Apportionment of end-to-end objectives ..... | 8 | +| 6.2.1 Allocation to the national portion of the end-to-end path..... | 9 | +| 6.2.2 Allocation to the international portion of the end-to-end path ..... | 9 | +| Annex A – Criteria for entry to and exit from the unavailable state..... | 10 | +| A.1 Criteria for a single direction ..... | 10 | +| A.2 Criterion for a bidirectional path..... | 10 | +| A.3 Criterion for a unidirectional path..... | 11 | +| A.4 Consequences on error performance measurements ..... | 11 | +| Annex B – Relationship between path performance monitoring and the block-based parameters ..... | 11 | +| B.1 General..... | 11 | +| B.1.1 Converting BIP measurements into errored blocks ..... | 11 | +| B.1.2 Block size for monitoring SDH paths..... | 11 | +| B.1.3 Anomalies..... | 12 | + +| | Page | +|----------------------------------------------------------------------------------------|-------------| +| B.1.4 Defects ..... | 12 | +| B.2 Estimation of the performance parameters ..... | 13 | +| B.3 Estimation of performance events at the far end of a path..... | 14 | +| Appendix I – Flow chart illustrating the recognition of anomalies ..... | 14 | +| Appendix II – Applicability of ITU-T Recommendation G.828 to non-public networks ..... | 17 | + +## **Error performance parameters and objectives for international, constant bit rate synchronous digital paths** + +# **1 Scope** + +This Recommendation specifies error performance events, parameters and objectives for synchronous digital paths. Subclauses 1.1 to 1.3 give further details. + +## **1.1 Application of this Recommendation** + +This Recommendation is applicable to international, constant bit rate digital paths based on Synchronous Digital Hierarchies. While this Recommendation specifically addresses objectives for international digital paths, the allocation principles can be applied to the design of error performance for national or private synchronous digital paths. This Recommendation is generic in that it defines the parameters and objectives for paths independent of the physical transport network providing the paths. + +Compliance with the performance specification of this Recommendation will, in most cases, also ensure that subtending connections will meet the requirements laid out in ITU-T Recommendations G.821 ( $N \times 64$ kbit/s) [5] and G.826 [6]. Therefore, this Recommendation is the only Recommendation required for designing the error performance of synchronous digital paths (see Note). In accordance with the definition of a digital path, path end points may be located at user's premises. + +NOTE – It is not required to apply this Recommendation to SDH paths using equipment designed prior to the adoption of this Recommendation in March 2000. Performance events and objectives for paths using equipment designed prior to this date are given in ITU-T G.826. + +Paths are used to support services such as circuit switched, packet switched and leased circuit services. The quality of such services, as well as the performance of the network elements belonging to the service layer, is outside of the scope of this Recommendation. However, G.828-based paths can carry ATM traffic. Synchronous digital paths meeting the objectives of this Recommendation will enable the ATM traffic to meet I.356 [9]. + +The error performance objectives are applicable to each direction of the path independently. The values apply end-to-end over a 27 500 km Hypothetical Reference Path (see Figure 3) which may include optical fibre, digital radio relay, metallic cable and satellite transmission systems. The performance of multiplex and cross-connect functions employing ATM techniques is not included in these values. + +The parameter definitions are block-based with the block repetition rate in accordance with SDH technology, making in-service measurement convenient. In addition to in-service measurements, compliance with this Recommendation can be assessed using out-of-service measurements or estimated by measures compatible with this Recommendation as those specified in Annex B. + +The objectives given in this Recommendation are long-term objectives to be met over an evaluation period of typically 30 consecutive days (one month). Shorter measurement periods required for maintenance and bringing-into-service are covered in ITU-T Recommendation M.2101 [10]. + +## 1.2 Transport network layers + +This Recommendation specifies the error performance of synchronous digital paths in a given transport network layer. Two cases are considered: + +- 1) End-to-end Synchronous Digital Hierarchy (SDH) transport. +- 2) SDH paths forming the physical layer portions of ATM connections. + +See 1.2.1 and 1.2.2 for details. + +NOTE – For the purpose of this Recommendation, SDH transport includes other SDH type systems such as the Synchronous Optical Network (SONET). + +### 1.2.1 SDH transport networks + +In the context of this Recommendation, an SDH digital path is a trail carrying an SDH payload and associated overhead through the layered transport network between the path terminating equipment (see Figure 1). ITU-T Recommendation M.2101 [10] provides Bringing into-Service (BIS) and maintenance requirements which ensure that G.828 objectives are met. + +![Diagram of an SDH Path Layer Network between points A and B.](07b17a620c75522d53916a11e12d1bff_img.jpg) + +The diagram shows a central oval labeled "SDH Path Layer Network" connected to two rectangular boxes labeled "A" and "B". Above the network, a double-headed arrow spans from A to B, labeled "Application of ITU-T Recommendation G.828". Below box B, the text "T1316620-94" is present. + +Diagram of an SDH Path Layer Network between points A and B. + +NOTE – A and B are path end points located at the terminations as defined in ITU-T Recommendation G.783 [2]. + +**Figure 1/G.828 – Application of ITU-T Recommendation G.828 for an end-to-end SDH path** + +### 1.2.2 ATM connections + +Where the path forms the physical part of an ATM connection (see Figure 2), the overall end-to-end performance of the ATM connection is defined by ITU-T Recommendation I.356 [9]. In this case, this Recommendation can be applied with an appropriate allocation to the performance between the path end points terminated by the physical layer of ATM cross-connects or switches (see Recommendation I.321 [8]). ATM transmission paths in the physical layer correspond to a stream of cells mapped into SDH frame structures. + +![Diagram showing the architectural relationship between ITU-T Recommendations G.828 and I.356 for ATM connections.](3b621c21b0af3a504a28d2547e87138f_img.jpg) + +The diagram illustrates three stacked protocol layers: AAL (ATM Adaptation Layer), ATM, and SDH. On the left, a stack of these three layers is shown. A line labeled "ITU-T Recommendation I.356" points from the AAL layer to a similar stack on the right. Between the left and right stacks, there is a section labeled "ITU-T Recommendation G.828" which contains two "SDH" boxes. The right stack also consists of AAL, ATM, and SDH layers. Below the diagram, a legend defines the layers: AAL (ATM Adaptation Layer), ATM (ATM Layer), and SDH (SDH Layer). The text "T1316630-95" is located at the bottom right of the diagram. + +Diagram showing the architectural relationship between ITU-T Recommendations G.828 and I.356 for ATM connections. + +**Figure 2/G.828 – Architectural relationship between ITU-T Recommendations G.828 and I.356 [9]** + +## 1.3 Allocation of end-to-end performance + +Allocations of end-to-end performance of synchronous digital paths are derived using the rules laid out in 6.2, which are length and complexity based. Detailed allocations of G.828 performance to the individual components (lines, sections, multiplexers and cross-connects, etc.) are outside the scope of this Recommendation, but when such allocations are performed, the requirements of 6.2 with regard to national and international allocations should be met. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.707 (1996), *Network node interface for the synchronous digital hierarchy (SDH)*. +- [2] ITU-T Recommendation G.783 (1997), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks*. +- [3] ITU-T Recommendation G.784 (1999), *Synchronous digital hierarchy (SDH) management*. +- [4] ITU-T Recommendation G.803 (2000), *Architecture of transport networks based on the synchronous digital hierarchy (SDH)*. +- [5] ITU-T Recommendation G.821 (1996), *Error performance of an international digital connection operating at a bit rate below the primary rate and forming part of an integrated services digital network*. +- [6] ITU-T Recommendation G.826 (1999), *Error performance parameters and objectives for international, constant bit rate digital paths at or above the primary rate*. +- [7] ITU-T Recommendation G.827 (2000), *Availability parameters and objectives for path elements of international constant bit rate digital paths at or above the primary rate*. +- [8] CCITT Recommendation I.321 (1991), *B-ISDN Protocol reference model and its application*. +- [9] ITU-T Recommendation I.356 (2000), *B-ISDN ATM layer cell transfer performance*. +- [10] ITU-T Recommendation M.2101 (2000), *Performance limits for bringing-into-service and maintenance of international SDH paths and multiplex sections*. + +# 3 Definitions and abbreviations + +## 3.1 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|-----|----------------------------| +| AAL | ATM Adaptation Layer | +| AIS | Alarm Indication Signal | +| ATM | Asynchronous Transfer Mode | +| AU | Administrative Unit | +| BBE | Background Block Error | + +| | | +|--------|--------------------------------------| +| BBER | Background Block Error Ratio | +| BIP | Bit Interleaved Parity | +| B-ISDN | Broadband ISDN | +| CBR | Constant Bit Rate | +| CSES | Consecutive Severely Errored Seconds | +| EB | Errored Block | +| EDC | Error Detection Code | +| ES | Errored Second | +| ESR | Errored Second Ratio | +| HP | Higher order Path | +| HPTC | Higher order Path Tandem Connection | +| HRP | Hypothetical Reference Path | +| IG | International Gateway | +| ISDN | Integrated Services Digital Network | +| ISM | In-Service Monitoring | +| LOF | Loss of Frame Alignment | +| LOM | Loss of Multiframe Alignment | +| LOP | Loss of Pointer | +| LOS | Loss of Signal | +| LP | Lower order Path | +| LPTC | Lower order Path Tandem Connection | +| LTC | Loss of Tandem Connection Monitoring | +| N-ISDN | Narrow-Band ISDN | +| OOS | Out-Of-Service | +| PEP | Path End Point | +| PLM | Payload Label Mismatch | +| RDI | Remote Defect Indication | +| REI | Remote Error Indication | +| RS | Regenerator Section | +| SDH | Synchronous Digital Hierarchy | +| SEP | Severely Errored Period | +| SEPI | Severely Errored Period Intensity | +| SES | Severely Errored Second | +| SESR | Severely Errored Second Ratio | +| SONET | Synchronous Optical Network | +| STM | Synchronous Transport Module | +| S UNEQ | Supervisory Unequipped | + +| | | +|------|------------------------------| +| TC | Tandem Connection | +| TCM | Tandem Connection Monitoring | +| TIM | Trace Identifier Mismatch | +| TU | Tributary Unit | +| UNEQ | Unequipped | +| VC | Virtual Container | + +## 3.2 Terms and Definitions + +This Recommendation defines the following terms: + +**3.2.1 hypothetical reference path:** A Hypothetical Reference Path (HRP) is defined as the whole means of digital transmission of a digital signal of a specified rate, including the path overhead, between equipment at which the signal originates and terminates. An end-to-end Hypothetical Reference Path spans a distance of 27 500 km. + +**3.2.2 SDH digital path:** An SDH digital path is a trail carrying an SDH payload and associated overhead through the layered transport network between the path terminating equipment. A digital path may be bidirectional or unidirectional and may comprise both customer owned portions and network operator owned portions. + +**3.2.3 Generic definition of the block:** This ITU-T Recommendation is based upon the error performance measurement of blocks consistent with a synchronous digital hierarchy frame. This clause offers a generic definition of the term "block" as follows: + +A block is a set of consecutive bits associated with the path; each bit belongs to one and only one block. Consecutive bits may not be contiguous in time. + +### 3.2.4 Error performance events + +**3.2.4.1 errored block (EB):** A block in which one or more bits are in error. + +**3.2.4.2 errored second (ES):** A one second period with one or more errored blocks or at least one defect (see Note 1). + +**3.2.4.3 severely errored second (SES):** A one-second period which contains $\geq 30\%$ errored blocks or at least one defect. SES is a subset of ES. (See Notes 1 and 2.) + +NOTE 1 – The defects and related performance criteria are listed in Annex B. + +NOTE 2 – To simplify measurement processes, the defect is used in the definition of SES instead of defining SES directly in terms of severe errors affecting the path. While this approach simplifies the measurement of SES, it should be noted that there may exist error patterns of severe intensity that would not trigger a defect as defined in Annex B. Thus, these would not be considered as an SES under this definition. If in the future such severe user-affecting events were found, this definition will have to be studied again. + +**3.2.4.4 background block error (BBE):** An errored block not occurring as part of an SES. + +### 3.2.5 Error performance parameters + +Error performance should only be evaluated whilst the path is in the available state. For a definition of the entry/exit criteria for the unavailable state see ITU-T Recommendation G.827 [7] and Annex A. + +**3.2.5.1 errored second ratio (ESR):** The ratio of ES in available time to total seconds in available time during a fixed measurement interval. + +**3.2.5.2 severely errored second ratio (SESR):** The ratio of SES in available time to total seconds in available time during a fixed measurement interval. + +**3.2.5.3 background block error ratio (BBER):** The ratio of BBE in available time to total blocks in available time during a fixed measurement interval. The count of total blocks excludes all blocks during SESs. + +### **3.2.6 Additional error performance event / performance parameter** + +The support of this event/of this parameter and its related functionalities within one network operator's domain is a network operator option. If implemented, the following definitions apply: + +**3.2.6.1 severely errored period (SEP):** A sequence of between 3 to 9 consecutive SES. The sequence is terminated by a second which is not a SES. (See Note 1.) + +NOTE 1 – The Severely Errored Period (SEP) event is identical to the CSES event contained in ITU-T Recommendation G.784 [3] on condition that the lower threshold is fixed at three consecutive SESs. + +**3.2.6.2 Severely Errored Period Intensity (SEPI):** The number of SEP events in available time, divided by the total available time in seconds. (See Notes 2, 3 and 4.) + +NOTE 2 – The SEPI parameter has a unit of (1/s). This is to enable the SEPI objective to be easily translated to the equivalent number of SEP events over a specific measurement interval. It should be noted that the SEP event has no significance over a time interval of less than three seconds. + +NOTE 3 – Ongoing studies of the SEP event and the SEPI parameter shall prove their usefulness in complementing the SESR parameter. Any objectives for the SEPI parameter (presently under study) shall empirically demonstrate this value. + +NOTE 4 – The impact of SEP/SEPI on customer services has to be investigated. + +# **4 Measurement of the block** + +## **4.1 In-service monitoring** + +Each block is monitored by means of an inherent (Bit Interleaved Parity) Error Detection Code (EDC). The EDC bits are physically separated from the block to which they apply. It is not normally possible to determine whether a block or its controlling EDC bits are in error. If there is a discrepancy between the EDC and its controlled block, it is always assumed that the controlled block is in error. + +No specific EDC is given in this generic definition but it is recommended that for in-service monitoring purposes, future designs should be equipped with an EDC capability such that the probability to detect an error event is $\geq 90\%$ assuming Poisson error distribution. + +Estimation of errored blocks on an in-service basis is dependent upon the path configuration and the EDC choice. Annex B describes how in-service estimates of errored blocks can be obtained from the ISM facilities of the SDH network fabric. + +## **4.2 Out-of-service measurements** + +Out-of-service measurements shall also be block-based. It is expected that the out-of-service error detection capability will be superior to the in-service capability described in 4.1. + +# **5 Performance monitoring at the near end and far end of a path** + +By monitoring SES events for both directions at a single path end point, a network provider is able to determine the unavailable state of the path (see Annex A). In some cases, it is also possible to monitor the full set of error performance parameters in both directions from one end of the path. Specific in-service indicators for deriving far end performance of a path are listed in Annex B. + +# 6 Error performance objectives + +## 6.1 End-to-end objectives + +Table 1 specifies the end-to-end objectives for a 27 500 km HRP in terms of the parameters defined in 3.2.5. The actual objectives applicable to a real path are derived from Table 1 using the allocation principles detailed in 6.2. Each direction of the path shall independently satisfy the allocated objectives for all parameters. In other words, a path fails to satisfy this Recommendation if any parameter exceeds the allocated objective in either direction at the end of the given evaluation period. The objectives given in this ITU-T Recommendation are understood to be long-term objectives to be met over an evaluation period of typically 30 consecutive days (1 month)1. + +**Table 1/G.828 – End-to-end error performance objectives for a 27 500 km international synchronous digital HRP** + +| Bit rate (kbit/s) | Path type | Blocks/s | ESR | SESR | BBER | SEPI | +|-------------------|--------------------|----------|----------|-------|--------------------------------|----------| +| 1 664 | VC-11, TC-11 | 2 000 | 0.01 | 0.002 | $5 \times 10^{-5}$ | (Note 3) | +| 2 240 | VC-12, TC-12 | 2 000 | 0.01 | 0.002 | $5 \times 10^{-5}$ | (Note 3) | +| 6 848 | VC-2, TC-2 | 2 000 | 0.01 | 0.002 | $5 \times 10^{-5}$ | (Note 3) | +| 48 960 | VC-3, TC-3 | 8 000 | 0.02 | 0.002 | $5 \times 10^{-5}$ | (Note 3) | +| 150 336 | VC-4, TC-4 | 8 000 | 0.04 | 0.002 | $1 \times 10^{-4}$ | (Note 3) | +| 601 344 | VC-4-4c, TC-4-4c | 8 000 | (Note 1) | 0.002 | $1 \times 10^{-4}$ | (Note 3) | +| 2 405 376 | VC-4-16c, TC-4-16c | 8 000 | (Note 1) | 0.002 | $1 \times 10^{-4}$ | (Note 3) | +| 9 621 504 | VC-4-64c, TC-4-64c | 8 000 | (Note 1) | 0.002 | $1 \times 10^{-3}$
(Note 2) | (Note 3) | + +NOTE 1 – ESR objectives tend to lose significance for applications at high bit rates and are therefore not specified for paths operating at bit rates above 160 Mbit/s. Nevertheless, it is recognized that the observed performance of synchronous digital paths is error-free for long periods of time even at Gbit/s rates; and that significant ESR indicates a degraded transmission system. Therefore, for maintenance purposes ES monitoring should be implemented within any error performance measuring devices operating at these rates. + +NOTE 2 – This BBER objective corresponds to a equivalent bit error ratio of $8.3 \times 10^{-10}$ , an improvement over the bit error ratio of $5.3 \times 10^{-9}$ for the VC-4 rate. Equivalent Bit Error Ratio is valuable as a rate-independent indication of error performance, as BBER objectives cannot remain constant as block sizes increase. + +NOTE 3 – SEPI objectives require further study. + +Synchronous digital paths operating at bit rates covered by this Recommendation are carried by transmission systems (digital sections) operating at higher bit rates. Such systems must meet their allocations of the end-to-end objectives for the highest bit rate paths which are foreseen to be carried. Meeting the allocated objectives for this highest bit rate path should be sufficient to ensure that all paths through the system are achieving their objective. For example, in SDH, an STM-1 section may + +1 In cases (e.g. paths transported via radio-relay or satellite systems) where a one month evaluation period may not permit accurate statistical estimation, a longer evaluation period (up to one year) may be used for design purposes. + +carry a VC-4 path and therefore the STM-1 section should be designed such that it will ensure that the objectives as specified in this Recommendation for the bit rate corresponding to a VC-4 path are met. + +NOTE 1 – Digital sections are defined for higher bit rates. In addition to this subclause, guidance on evaluating the performance of digital sections can be found in a Recommendation dealing with section performance events. + +NOTE 2 – Objectives are allocated in this Recommendation to the national and international portions of a path. In the above example, if the STM-1 section does not form a complete national or international portion, the corresponding national/international allocation must be subdivided to determine the appropriate allocation for the digital section. This is outside the scope of this Recommendation. + +## 6.2 Apportionment of end-to-end objectives + +The apportionment methodology in this subclause specifies the levels of performance expected from the national and international portions of an HRP. Further subdivision of these objectives is beyond the scope of this Recommendation. (See Figure 3.) + +![Diagram of a Hypothetical Reference Path (HRP) showing national and international portions between two terminating countries, separated by four intermediate countries. The path includes PEPs at the ends and IGs at the boundaries and between intermediate countries. The total length is 27,500 km.](a26e142d3df5bef41a84a9dd099d7825_img.jpg) + +The diagram illustrates a Hypothetical Reference Path (HRP) between two 'Terminating country' endpoints. At each end, there is a 'PEP (Note 1)' represented by a solid black square. The path consists of several segments: + + +- A 'National portion' at each end, starting from the PEP and ending at an 'IG' (International Gateway, represented by a solid black square). +- An 'International portion' that spans between the first IG of the first terminating country and the last IG of the second terminating country. +- Between the first and last IGs, there are four 'Intermediate countries (Note 3)'. Each intermediate country contains an 'IG'. +- The segment between the second and third IGs (counting from left to right) is labeled 'Inter-country (e.g. Path carried over a submarine cable)'. +- A dashed line separates the second and third IGs. +- The total length of the path is labeled 'Hypothetical Reference Path 27 500 km'. +- A reference code 'T1316640-99' is shown at the bottom right. + +Diagram of a Hypothetical Reference Path (HRP) showing national and international portions between two terminating countries, separated by four intermediate countries. The path includes PEPs at the ends and IGs at the boundaries and between intermediate countries. The total length is 27,500 km. + +NOTE 1 – If a path is considered to terminate at the IG, only the international portion allocation applies. + +NOTE 2 – One or two International Gateways (entry or exit) may be defined per intermediate country. + +NOTE 3 – Four intermediate countries are assumed. + +**Figure 3/G.828 – Hypothetical Reference Path** + +For the purposes of this Recommendation the boundary between the national and international portions is defined to be at an International Gateway which usually corresponds to a cross-connect, a higher-order multiplexer or a switch (N-ISDN or B-ISDN). IGs are always terrestrially based equipment physically resident in the terminating (or intermediate) country. Higher-order paths (relative to the HRP under consideration) may be used between IGs. Such paths receive only the allocation corresponding to the international portion between the IGs. In intermediate countries, the IGs are only located in order to calculate the overall length of the international portion of the path in order to deduce the overall allocation. + +The following allocation methodology applies to each parameter defined in 3.2.5 and takes into account both the length and complexity of the international path. All paths should be engineered to meet their allocated objectives as described in 6.2.1 and 6.2.2. If the overall allocation exceeds 100%, then the performance of the path may not fulfil the objectives of Table 1. Network Operators should note that if performance could be improved in practical implementations to be superior to allocated objectives, the occurrence of paths exceeding the objectives of Table 1 can be minimized. + +### 6.2.1 Allocation to the national portion of the end-to-end path + +Each national portion is allocated a fixed block allowance of 17.5% of the end-to-end objective. Furthermore, a distance based allocation is added to the block allowance. The actual route length between the PEP and IG should first be calculated if known. The air route distance between the PEP and IG should also be determined and multiplied by an appropriate routing factor. This routing factor is specified as follows: + +- If the air route distance is $< 1\ 000$ km, the routing factor is 1.5; +- If the air route distance is $\geq 1\ 000$ km and $< 1\ 200$ km, the calculated route length is taken to be 1 500 km; +- If the air route distance is $\geq 1\ 200$ km, the routing factor is 1.25. + +When both actual and calculated route lengths are known, the smaller value is retained. This distance should be rounded up to the nearest 100 km. An allocation of 0.2% per 100 km is then applied to the resulting distance. The two national portions are allocated a minimum of 500 km (i.e. 1%) each. + +NOTE – If a path comprises portions that are privately owned (private in this context means that the network portion is customer owned and not available to the public), end-to-end performance objectives apply to the portion situated between the two Network Terminating Equipment (NTE). Between the NTE and the Terminal Equipment (TE), no specific requirements are given. However, careful attention should be paid concerning this portion because overall performance depends on it. Appendix II contains details for the case of Leased Circuits. + +While the performance sub-allocation of the 17.5% national portion block allowance is beyond the scope of this Recommendation, it is the expectation that such a sub-allocation would be done by national standards bodies or regulators in an equitable manner. When making such sub-allocation, the national standards bodies or regulators are urged to take into consideration the empirical evidence that most of the error impairments can occur in that part of the path nearest to its end point. + +When a national portion includes a satellite hop, a total allowance of 42% of the end-to-end objectives in Table 1 is allocated to this national portion. The 42% allowance completely replaces both the distance-based allowance and the 17.5% block allowance otherwise given to national portions. + +### 6.2.2 Allocation to the international portion of the end-to-end path + +The international portion is allocated a block allowance of 2% per intermediate country plus 1% for each terminating country. Furthermore, a distance based allocation is added to the block allowance. As the international path may pass through intermediate countries, the actual route length between consecutive IGs (one or two for each intermediate country) should be added to calculate the overall length of the international portion. The air route distance between consecutive IGs should also be determined and multiplied by an appropriate routing factor. This routing factor is specified as follows for each element between IGs: + +- If the air route distance between two IGs is $< 1\ 000$ km, the routing factor is 1.5; +- If the air route distance is $\geq 1\ 000$ km and $< 1\ 200$ km, the calculated route length is taken to be 1 500 km; +- If the air route distance between two IGs is $\geq 1\ 200$ km, the routing factor is 1.25. + +When both actual and calculated route lengths are known, the smaller value is retained for each element between IGs for the calculation of the overall length of the international portion. This overall distance should be rounded up to the nearest 100 km but shall not exceed 26 500 km. An allocation of 0.2% per 100 km is then applied to the resulting distance. + +Independent of the distance spanned, any satellite hop in the international portion receives a 35% allocation of the objectives in Table 1. The 35% allowance completely replaces all distance-based and block allowances otherwise given to parts of the international portion spanned by the satellite hop. + +## ANNEX A + +## Criteria for entry to and exit from the unavailable state + +## A.1 Criteria for a single direction + +A period of unavailable time begins at the onset of ten consecutive SES events. These ten seconds are considered to be part of unavailable time. A new period of available time begins at the onset of 10 consecutive non-SES events. These ten seconds are considered to be part of available time. SEP indicates a severe condition, which does not result in unavailability. Figure A.1 illustrates the definition of criteria for transition to/from the unavailable state, including the relationship with SEP. + +![Figure A.1/G.828 – Example of unavailability determination. This diagram shows a timeline of seconds categorized into four types: Severely Errored Second (SES) represented by a solid grey square, Severely Errored Period (SEP) represented by a square with an 'X', Errored Second (ES) represented by a square with a cross, and Error-free Second represented by a white square. The timeline shows a sequence of these squares. A 'Period of unavailable time' is marked with a double-headed arrow, starting at the onset of 10 consecutive SES events and ending at the onset of 10 consecutive non-SES events. The duration of this period is labeled '10 s'. A 'Period of available time' is marked with a double-headed arrow, starting at the onset of 10 consecutive non-SES events and continuing. The duration of this period is also labeled '10 s'. A 'Severely Errored Period (SEP)' is indicated by a square with an 'X' that spans less than 10 seconds, labeled '<10 s'. The text 'Unavailability detected' is placed below the start of the unavailable period, and 'Availability detected' is placed below the start of the available period. The diagram is labeled 'T1316650-99' at the bottom right.](fc857414626a8d94d132e12d9afe52a4_img.jpg) + +Figure A.1/G.828 – Example of unavailability determination. This diagram shows a timeline of seconds categorized into four types: Severely Errored Second (SES) represented by a solid grey square, Severely Errored Period (SEP) represented by a square with an 'X', Errored Second (ES) represented by a square with a cross, and Error-free Second represented by a white square. The timeline shows a sequence of these squares. A 'Period of unavailable time' is marked with a double-headed arrow, starting at the onset of 10 consecutive SES events and ending at the onset of 10 consecutive non-SES events. The duration of this period is labeled '10 s'. A 'Period of available time' is marked with a double-headed arrow, starting at the onset of 10 consecutive non-SES events and continuing. The duration of this period is also labeled '10 s'. A 'Severely Errored Period (SEP)' is indicated by a square with an 'X' that spans less than 10 seconds, labeled '<10 s'. The text 'Unavailability detected' is placed below the start of the unavailable period, and 'Availability detected' is placed below the start of the available period. The diagram is labeled 'T1316650-99' at the bottom right. + +Figure A.1/G.828 – Example of unavailability determination + +### A.2 Criterion for a bidirectional path + +A bidirectional path is in the unavailable state if either one or both directions are in the unavailable state. This is shown in Figure A.2. + +![Figure A.2/G.828 – Example of the unavailable state of a path. This diagram shows three horizontal lines representing 'Forward direction', 'Backward direction', and 'Path'. The 'Forward direction' line has two grey rectangular blocks representing the 'Unavailable state'. The 'Backward direction' line also has two grey rectangular blocks. The 'Path' line has two grey rectangular blocks. Vertical dashed lines connect the start and end of the unavailable state blocks across the three lines. The legend indicates that a grey rectangle represents the 'Unavailable state'. The diagram is labeled 'T1306440-95' at the bottom right.](865a630eb1b708bd28250dfeb33dd8f1_img.jpg) + +Figure A.2/G.828 – Example of the unavailable state of a path. This diagram shows three horizontal lines representing 'Forward direction', 'Backward direction', and 'Path'. The 'Forward direction' line has two grey rectangular blocks representing the 'Unavailable state'. The 'Backward direction' line also has two grey rectangular blocks. The 'Path' line has two grey rectangular blocks. Vertical dashed lines connect the start and end of the unavailable state blocks across the three lines. The legend indicates that a grey rectangle represents the 'Unavailable state'. The diagram is labeled 'T1306440-95' at the bottom right. + +Figure A.2/G.828 – Example of the unavailable state of a path + +### **A.3 Criterion for a unidirectional path** + +The criterion for a unidirectional path is defined in A.1 above. + +## **A.4 Consequences on error performance measurements** + +When a bidirectional path is in the unavailable state, ES, SES and BBE counts may be collected in both directions and may be helpful in the analysis of the trouble. However, it is recommended that these ES, SES and BBE counts are not included in estimates of ESR, SESR and BBER performance (see 3.2.5). + +Some existing systems may not support the above requirement. For these systems, the performance of a bidirectional path can be approximated by evaluating the parameters in each direction, independently of the state of availability of the other direction. It should be noted that this approximation method may result in a worse estimate of performance in the event that only one direction of a bidirectional path becomes unavailable. + +NOTE – This is not an issue for unidirectional paths. + +## **ANNEX B** + +## **Relationship between path performance monitoring and the block-based parameters** + +### **B.1 General** + +In addition to path performance monitoring, this Annex covers Tandem Connection Monitoring (TCM) as shown in Tables B.1 to B.4. VC-n and TC-n trails are equivalent from a performance perspective. The established rules for VC-n apply also to TC-n. Further details are given in ITU-T Recommendations G.707 [1], G.783 [2] and G.803 [4]. + +#### **B.1.1 Converting BIP measurements into errored blocks** + +Subclause 3.2.4 describes error performance events used in defining performance parameters. The method of converting BIP measurements into errored blocks is described below. + +Since this ITU-T Recommendation defines a block as consecutive bits associated with a path, each BIP-n (Bit Interleaved Parity, order "n") in the SDH path overhead pertains to a single defined block. For the purpose of this annex, a BIP-n corresponds to a G.828 block. The BIP-n is NOT interpreted as checking "n" separate interleaved parity check blocks. If any of the "n" separate parity checks fails, the block is assumed to be in error. + +NOTE – It shall be noted that BIP-2 does not satisfy the error detection probability of $\geq 90\%$ . + +#### **B.1.2 Block size for monitoring SDH paths** + +The number of bits per block for in-service performance monitoring of SDH Paths, as specified in ITU-T Recommendation G.707 [1], are given in Table B.1. Paths operating at VC-11, VC-12 or VC-2 rates use 500 $\mu$ sec measurement blocks, i.e. 2 000 blocks per second. + +**Table B.1/G.828 – Block sizes for synchronous digital path performance monitoring** + +| Bit rate (kbit/s) | Path type | SDH block size used in G.828 | EDC | +|-------------------|--------------------|------------------------------|-------| +| 1 664 | VC-11, TC-11 | 832 bits | BIP-2 | +| 2 240 | VC-12, TC-12 | 1 120 bits | BIP-2 | +| 6 848 | VC-2, TC-2 | 3 424 bits | BIP-2 | +| 48 960 | VC-3, TC-3 | 6 120 bits | BIP-8 | +| 150 336 | VC-4, TC-4 | 18 792 bits | BIP-8 | +| 601 344 | VC-4-4c, TC-4-4c | 75 168 bits | BIP-8 | +| 2 405 376 | VC-4-16c, TC-4-16c | 300 672 bits | BIP-8 | +| 9 621 504 | VC-4-64c, TC-4-64c | 1 202 688 bits | BIP-8 | + +#### B.1.3 Anomalies + +In-service anomaly conditions are used to determine the error performance of an SDH path when the path is not in a defect state. The following anomaly is defined: + +a1 an EB as indicated by an EDC. (See B.1.1) + +#### B.1.4 Defects + +In-service defect conditions defined in ITU-T Recommendations G.707 [1] and G.783 [2] are used to determine the change of performance state which may occur on a path. Tables B.2 and B.3 show the defects used in this Recommendation. + +**Table B.2/G.828 – Defects resulting in a near-end Severely Errored Second** + +| Near end defects (Notes 5, 6 and 7) | | | Kind of path | +|-------------------------------------|-------------------------|--------------------|----------------------------------------------------------------------| +| Path termination | Non-Intrusive Monitor | Tandem Connection | | +| LP UNEQ (Note 3) | LP UNEQ (Notes 3 and 4) | LPTC UNEQ (Note 3) | Applicable to lower order paths and lower order tandem connections | +| LP TIM | LP TIM | LPTC TIM | | +| – | – | LPTC LTC | | +| – | LP VC AIS (Note 2) | – | | +| TU LOP | TU LOP | TU LOP | | +| TU AIS | TU AIS | TU AIS | | +| HP LOM (Note 1) | HP LOM (Note 1) | HP LOM (Note 1) | | +| HP PLM | HP PLM | HP PLM | | +| HP UNEQ (Note 3) | HP UNEQ (Notes 3 and 4) | HPTC UNEQ (Note 3) | | +| HP TIM | HP TIM | HPTC TIM | Applicable to higher order paths and higher order tandem connections | +| – | – | HPTC LTC | | +| – | HP VC AIS (Note 2) | – | | +| AU LOP | AU LOP | AU LOP | | +| AU AIS | AU AIS | AU AIS | | + +**Table B.2/G.828 – Defects resulting in a near-end Severely Errored Second (concluded)** + +| | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NOTE 1 – This defect is not related to VC-3. | +| NOTE 2 – VC AIS defect applies to monitoring a path at an intermediate point by means of non-intrusive monitoring. | +| NOTE 3 – Paths not actually completed, e.g. during path set-up, will contain the unequipped VC-n signal. | +| NOTE 4 – Two types of non-intrusive monitor functions are defined in ITU-T Recommendation G.783. The original (version 1) type detect the UNEQ defect when an unequipped or a supervisory-unequipped VC signal is received. The advanced (version 2) type detects the UNEQ condition as type 1 but validates this condition by means of checking the content of the trace identifier; the receipt of a supervisory-unequipped VC signal will not result in an UNEQ defect. Neither will the receipt of a supervisory-unequipped VC signal result in the contribution of UNEQ condition to performance monitoring; if the supervisory-unequipped VC signal was not the expected signal, TIM defect will contribute to performance monitoring instead. | +| NOTE 5 – The above defects are path defects only. Section defects such as MS AIS, RS TIM, STM LOF and STM LOS give rise to an AIS defect in the path layers. | +| NOTE 6 – When a near-end SES is caused by a near-end defect as defined above, the far-end performance event counters are not incremented, i.e. an error-free period is assumed. When a near-end SES results from $\geq 30\%$ errored blocks, the far-end performance evaluation continues during the near-end SES. This approach does not allow reliable evaluation of Far-End data if the Near-End SES is caused by a defect. It should be noted in particular, that the evaluation of Far-End events (such as SES or Unavailability) can be inaccurate in the case where Far-End SESs occur in coincidence with Near-End SESs caused by a defect. Such inaccuracies cannot be avoided, but are negligible in practice because of the low probability of the occurrence of such phenomena. | +| NOTE 7 – Refer to ITU-T Recommendation G.783 for defects contributing to performance monitoring in each trail termination sink function. | + +**Table B.3/G.828 – Defects resulting in a far-end Severely Errored Second** + +| Far end defects | | | Kind of path | +|------------------|-----------------------|-------------------|----------------------------------------------------------------------| +| Path termination | Non-Intrusive Monitor | Tandem Connection | | +| LP RDI | LP RDI | LPTC TC RDI | Applicable to lower order paths and lower order tandem connections | +| HP RDI | HP RDI | HPTC TC RDI | Applicable to higher order paths and higher order tandem connections | + +### B.2 Estimation of the performance parameters + +For SDH transmission paths, the full set of performance parameters shall be estimated using the following events: + +ES: An ES is observed when, during one second, at least one anomaly $a_1$ , or one defect according to Tables B.2 and B.3 occurs. For the ES event, the actual count of EBs is irrelevant, it is only the fact that an EB has occurred in a second which is significant. + +SES: An SES is observed when, during one second, at least 30% EBs – derived from anomaly $a_1$ or one defect according to Tables B.2 and B.3 occur (see Table B.4). + +BBE: A BBE is observed when an anomaly $a_1$ occurs in a block not being part of an SES. + +NOTE – The errored block threshold resulting in an SES is shown in Table B.4 for each SDH path type. + +**Table B.4/G.828 – Threshold for the declaration of a severely errored second** + +| Bit rate (kbit/s) | Path type | Threshold for SES (Number of Errored Blocks/s) | +|-------------------|--------------------|------------------------------------------------| +| 1 664 | VC-11, TC-11 | 600 | +| 2 240 | VC-12, TC-12 | 600 | +| 6 848 | VC-2, TC-2 | 600 | +| 48 960 | VC-3, TC-3 | 2 400 | +| 150 336 | VC-4, TC-4 | 2 400 | +| 601 344 | VC-4-4c, TC-4-4c | 2 400 | +| 2 405 376 | VC-4-16c, TC-4-16c | 2 400 | +| 9 621 504 | VC-4-64c, TC-4-64c | 2 400 | + +### **B.3 Estimation of performance events at the far end of a path** + +The following indications available at the near end or at an intermediate point along the path/tandem connection are used to estimate the performance events (occurring at the far end) for the reverse direction: + +- Higher and lower order path/tandem connection RDI and REI (ITU-T Recommendation G.707 [1]). +- Higher or lower order path/tandem connection REIs are anomalies which are used to determine the occurrence of ES, BBE and SES at the far end. +- Higher or lower order path/tandem connection RDIs are defects which estimate the occurrence of SES at the far end. + +## **APPENDIX I** + +## **Flow chart illustrating the recognition of anomalies** + +Notes to Figures I.1 and I.2: + +NOTE 1 – The determination of unavailability time introduces a delay of 10 seconds. This delay should be considered when counting BBE, ES and SES. + +NOTE 2 – cES, cSES, cSEP and cBBE represent counts of ES, SES, SEP and BBE respectively. These counts are reset at the start of a measurement period. + +NOTE 3 – EB is the count of errored blocks within an ES whilst %EB represents the proportion of errored blocks within an ES compared to the number of blocks per second. + +NOTE 4 – G.828 parameters can be evaluated during, or at the end of, a measurement period P as follows, taking into account Unavailable Seconds (UAS): + +$$\text{BBER} = \text{cBBE} / [(P - \text{UAS}) \cdot \text{blocks/second}]$$ + +$$\text{ESR} = \text{cES} / (P - \text{UAS})$$ + +$$\text{SESR} = \text{cSES} / (P - \text{UAS})$$ + +$$\text{SEPI} = \text{cSEP} / (P - \text{UAS})$$ + +NOTE 5 – In the simplified diagrams, no action is taken if the path is in the unavailable state. This is because the diagram does not consider the transition between availability states when, in fact, event counters must be modified retrospectively. In practice, the status of a second (i.e. error-free, ES or SES) must always be determined before a test is made on the status of path availability. In other words, error events are always detected regardless of whether the path is available or not – only the *counting* of events is inhibited during unavailability periods for the purposes of long-term performance monitoring. This process is reflected in the flow chart although consequent actions on changes of availability state are not. + +![Flowchart for recognition of anomalies, defects, errored blocks, ES, SES and BBE. It starts with 'Monitored Second' and proceeds through decision diamonds for 'Defects?', 'Anomalies?', and '%EB ≥ 30?'. It includes logic for counting errored seconds (cES), errored blocks (cBBE), and severely errored seconds (cSES) based on path availability and error thresholds. The flowchart ends at 'End'.](812e188283162af0b54fb3e30ffee51b_img.jpg) + +``` + +graph TD + Start([Monitored Second]) --> Defects{Defects?} + Defects -- Y --> PathAvail1{Path in available State?} + Defects -- N --> Anomalies{Anomalies?} + Anomalies -- Y --> EB30{"%EB ≥ 30?"} + Anomalies -- N --> End + EB30 -- Y --> SES_note["SES +(and therefore an ES)"] + EB30 -- N --> ES_note["ES +(but not a SES)"] + SES_note --> PathAvail2{Path in available State?} + ES_note --> PathAvail1 + PathAvail1 -- Y --> cES1["cES = cES + 1"] + PathAvail1 -- N --> End + cES1 --> cBBE["cBBE = cBBE + EB(s)"] + cBBE --> End + PathAvail2 -- Y --> cES2["cES = cES + 1"] + PathAvail2 -- N --> End + cES2 --> cSES["cSES = cSES + 1"] + cSES --> End + T1316660-99[T1316660-99] + +``` + +Flowchart for recognition of anomalies, defects, errored blocks, ES, SES and BBE. It starts with 'Monitored Second' and proceeds through decision diamonds for 'Defects?', 'Anomalies?', and '%EB ≥ 30?'. It includes logic for counting errored seconds (cES), errored blocks (cBBE), and severely errored seconds (cSES) based on path availability and error thresholds. The flowchart ends at 'End'. + +**Figure I.1/G.828 – Recognition of anomalies, defects, errored blocks, ES, SES and BBE** + +![Flowchart for Recognition of SEP. It starts with a starting condition of n consecutive SESs preceded and terminated by non-SES. It then checks if the path is available. If not, it skips to the end. If available, it checks if n < 3. If yes, it increments cSES by n. If no, it checks if n > 9. If yes, it goes to an unavailable state. If no, it checks if a SEP event of n seconds occurs in available time. If yes, it increments cSEP by 1 and cSES by n. All paths lead to the end.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +``` + +graph TD + Start([Starting condition: +n consecutive SESs preceded +and terminated by non-SES]) --> Path{Path in +available state prior to +n consecutive SESs?} + Path -- N --> End([End]) + Path -- Y --> n3{n < 3?} + n3 -- Y --> cSES_n[cSES = cSES + n] + n3 -- N --> n9{n > 9?} + n9 -- Y --> Unavailable[Unavailable state] + n9 -- N --> SEP_event{SEP event of n seconds +occurring in available time} + SEP_event -- Y --> cSEP_cSES[cSEP = cSEP + 1 +cSES = cSES + n] + SEP_event -- N --> End + cSES_n --> End + Unavailable --> End + cSEP_cSES --> End + +``` + +*Do not count the occurrence +of SEPs for the purposes of +performance assessment* + +T1316670-99 + +Flowchart for Recognition of SEP. It starts with a starting condition of n consecutive SESs preceded and terminated by non-SES. It then checks if the path is available. If not, it skips to the end. If available, it checks if n < 3. If yes, it increments cSES by n. If no, it checks if n > 9. If yes, it goes to an unavailable state. If no, it checks if a SEP event of n seconds occurs in available time. If yes, it increments cSEP by 1 and cSES by n. All paths lead to the end. + +**Figure I.2/G.828 – Recognition of SEP** + +## APPENDIX II + +### Applicability of ITU-T Recommendation G.828 to non-public networks + +Figure II.1 depicts a typical leased circuit situation where a path is composed of three independent networks: Two private networks at both path ends and a public network connecting them where the public network provides a leased circuit to connect the two private networks. + +However, the problem is not restricted to the case shown in the figure but is of more general nature. For instance, similar considerations are applicable in cases where the public network operator has no access to the path end point. + +![Diagram of a digital path composed of two private networks and a leased circuit provided by a public network operator.](844077b3034f0030b404207db0ad76b4_img.jpg) + +The diagram illustrates a digital path across three countries: Terminating country 1, Intermediate countries, and Terminating country 2. The path consists of the following components from left to right: Terminal Equipment (TE), Network Terminating Equipment (NTE), International Gateway (IG), IG, IG, IG, NTE, and TE. The path is divided into segments: Private network (between TE and NTE), National portion (between NTE and IG), International portion (between the IG in Terminating country 1 and the IG in Terminating country 2), National portion (between IG and NTE), and Private network (between NTE and TE). A 'Leased circuit' is indicated between the NTE in Terminating country 1 and the NTE in Terminating country 2. The 'End-to-end path' is shown as the entire sequence from the first TE to the last TE. A reference code 'T1316680-99' is present in the bottom right corner of the diagram area. + +TE Terminal Equipment +NTE Network Terminating Equipment +IG International Gateway + +Diagram of a digital path composed of two private networks and a leased circuit provided by a public network operator. + +**Figure II.1/G.828 – Digital path composed of two private networks and a leased circuit provided by a public network operator** + +Taking into account that a public operator can only control the public network from NTE to NTE (Network Terminating Equipment), no performance objectives can be given for the portion between NTE and TE. Nevertheless, transmission performance between NTEs may be estimated e.g. by using non-intrusive monitoring. + +It may also be that the public network operator provides the connection by other means than a leased circuit. + +## **SERIES OF ITU-T RECOMMENDATIONS** + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.8310-202012-I_PDF-E/raw.md b/marked/G/T-REC-G.8310-202012-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..9a48fab3fd0a220c922ac889599ccd53c6d8c74d --- /dev/null +++ b/marked/G/T-REC-G.8310-202012-I_PDF-E/raw.md @@ -0,0 +1,678 @@ + + +International Telecommunication Union + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.8310** + +(12/2020) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Packet over Transport aspects – Mobile network transport +aspects + +# --- **Architecture of the metro transport network** + +Recommendation ITU-T G.8310 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| Ethernet over Transport aspects | G.8000–G.8099 | +| MPLS over Transport aspects | G.8100–G.8199 | +| Synchronization, quality and availability targets | G.8200–G.8299 | +| Mobile network transport aspects | G.8300–G.8399 | +| Service Management | G.8600–G.8699 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.8310 + +# Architecture of the metro transport network + +## Summary + +Recommendation ITU-T G.8310 describes the functional architecture of the metro transport network (MTN) using the modelling methodology described in Recommendations ITU-T G.800 and ITU-T G.805. MTN is primarily intended to support transport of distributed radio access network (D-RAN) and cloud radio access network (C-RAN) traffic. The MTN functionality is described from a network level viewpoint, taking into account the client characteristic information, client/server layer associations, networking topology, and layer network functionality that provide multiplexing, routing and supervision of the digital clients. + +MTN consists of two non-recursive layers, the MTN path layer, and the MTN section layer. The MTN path layer uses the MTN section layer as its server layer. The MTN path layer provides configurable connection-oriented connectivity. The server layer for the MTN section layer is provided by 50GBASE-R, 100GBASE-R, 200GBASE-R, and 400GBASE-R Ethernet interfaces. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.8310 | 2020-12-22 | 15 | 11.1002/1000/14516 | + +## Keywords + +Ethernet, FlexE, metro transport network, MTN. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2021 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Functional architecture of the MTN ..... | 3 | +| 7 MTN digital layer networks..... | 4 | +| 7.1 MTNP layer network..... | 5 | +| 7.2 MTNS layer ..... | 7 | +| 7.3 Client/server associations ..... | 9 | +| 8 Architecture of the media network supporting the MTN ..... | 9 | +| 8.1 Media constructs..... | 9 | +| 8.2 Optical tributary signal group (OTSiG) ..... | 10 | +| 8.3 Client/server associations ..... | 12 | +| 9 Management capabilities ..... | 13 | +| 9.1 Capabilities ..... | 13 | +| 9.2 Connection supervision techniques ..... | 14 | +| 9.3 Connection supervision applications ..... | 14 | +| 10 Survivability techniques ..... | 15 | +| Annex A – Relationship of MTN to other technologies ..... | 16 | +| Bibliography..... | 17 | + + + +# Recommendation ITU-T G.8310 + +# Architecture of the metro transport network + +# 1 Scope + +This Recommendation describes the functional architecture of the metro transport network (MTN) using the modelling methodology described in [ITU-T G.800], [ITU-T G.805] for the digital layer networks and [ITU-T G.807] for the optical media network. + +The MTN functionality is described from a network-level viewpoint. This takes into account the characteristic information (CI) of the client (Ethernet MAC frames), the client/server layer associations, network topology, the network structure, and the layer network functionalities that provide multiplexing, routing, supervision, performance assessment and network survivability for the client. The digital layers of the MTN use the frame formats defined in [ITU-T G.8312]. The media portion of the network is defined in [IEEE 802.3] and is described, in this Recommendation, in terms of media constructs described in [ITU-T G.807]. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.800] Recommendation ITU-T G.800 (2016), *Unified functional architecture of transport networks*. +- [ITU-T G.805] Recommendation ITU-T G.805 (2000), *Generic functional architecture of transport networks*. +- [ITU-T G.807] Recommendation ITU-T G.807 (2020), *Generic functional architecture of the optical media network*. +- [ITU-T G.808.1] Recommendation ITU-T G.808.1 (2014), *Generic protection switching - Linear trail and subnetwork protection*. +- [ITU-T G.959.1] Recommendation ITU-T G.959.1 (2018), *Optical transport network physical layer interfaces*. +- [ITU-T G.7712] Recommendation ITU-T G.7712/Y.1703 (2019), *Architecture and specification of data communication network*. +- [ITU-T G.8312] Recommendation ITU-T G.8312 (2021), *Interfaces for the metro transport network*. +- [IEEE 802.3] IEEE Std 802.3 (2018), *IEEE Standard for Ethernet*. +- [OIF FLEXE IA] Optical Internetworking Forum (OIF), *Flex Ethernet Implementation Agreement 2.1* (2019). + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **access point (AP)**: See [ITU-T G.805] +- 3.1.2 **adaptation**: See [ITU-T G.805] +- 3.1.3 **adapted information (AI)**: See [ITU-T G.805] +- 3.1.4 **characteristic information (CI)**: See [ITU-T G.805] +- 3.1.5 **connection supervision**: See [ITU-T G.805] +- 3.1.6 **connection**: See [ITU-T G.805] +- 3.1.7 **connection point**: See [ITU-T G.805] +- 3.1.8 **forwarding point**: See [ITU-T G.800] +- 3.1.9 **forwarding end point**: See [ITU-T G.800] +- 3.1.10 **layer network**: See [ITU-T G.805] +- 3.1.11 **link**: See [ITU-T G.805] +- 3.1.12 **optical tributary signal (OTSi)**: See [ITU-T G.959.1] +- 3.1.13 **optical tributary signal group (OTSiG)**: See [ITU-T G.807] +- 3.1.14 **subnetwork**: See [ITU-T G.805] +- 3.1.15 **topological component**: See [ITU-T G.805] +- 3.1.16 **transport entity**: See [ITU-T G.800] +- 3.1.17 **transport processing function**: See [ITU-T G.805] + +## 3.2 Terms defined in this Recommendation + +None. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-------|----------------------------------| +| AI | Adapted Information | +| AIS | Alarm Indication Signal | +| AP | Access Point | +| CI | Characteristic Information | +| CP | Connection Point | +| C-RAN | Cloud Radio Access Network | +| D-RAN | Distributed Radio Access Network | +| ETH | Ethernet MAC layer | +| FEC | Forward Error Correction | +| FlexE | Flex Ethernet | +| FP | Forwarding Point | + +| | | +|-------|-----------------------------------| +| FwEP | Forwarding End Point | +| IPG | Inter-packet Gap | +| M-AI | Modulator Adapted Information | +| MTN | Metro Transport Network | +| MTNP | MTN Path | +| MTNS | MTN Section | +| NMC | Network Media Channel | +| NMCG | NMC Group | +| OCI | Open Connection Indication | +| OSME | Optical Signal Maintenance Entity | +| OTSi | Optical Tributary Signal | +| OTSiG | OTSi Group | +| PCS | Physical Coding Sublayer | +| PMA | Physical Medium Attachment | +| PMD | Physical Medium Dependent | +| PTP | Precision Time Protocol | +| SSF | Server Signal Fail | +| TTI | Trail Trace Identifier | + +# 5 Conventions + +This Recommendation uses the diagrammatic conventions defined in [ITU-T G.800], [ITU-T G.805] and [ITU-T G.807]. + +The forwarding point (FP), defined in [ITU-T G.800], is used in this Recommendation and is equivalent to the connection point (CP), defined in [ITU-T G.805]. + +This Recommendation uses the following textual conventions to identify information elements: + +**Block:** A 66-bit information element. The first two bits are a sync header which identifies the type of block; the remaining 64 bits carry data or control information. The 64B/66B block coding format is described in clause 82 of [IEEE 802.3]. + +**Sequence:** A series of information elements for which sequential arrangement must be maintained during transmission, but the time interval between information elements need not be maintained. + +**Stream:** A sequence where the time interval between information elements is maintained. + +# 6 Functional architecture of the MTN + +The metro transport network (MTN) consists of two non-recursive digital layer networks; the MTN path (MTNP) layer and the MTN section (MTNS) layer. The rates and formats used in the MTN are defined in [ITU-T G.8312]. + +The MTNS is supported by an MTN optical media layer. The MTN media layer provides fixed point-to-point connections between Ethernet interfaces. The layer structure of the MTN is shown in Figure 6-1. + +![](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +| | | | +|----------------------------------------------------|--------------------------------------|-------------------------------| +| Digital client of the MTN
(Ethernet MAC frames) | | | +| Path (MTNP) | MTN
digital layers | | +| Section (MTNS) | | | +| OTSiG | Ethernet
optical signals | MTN
optical media
layer | +| Media constructs | Ethernet
optical media
network | | + +**Figure 6-1 – MTN layer structure** + +The only client defined for the MTN is Ethernet MAC frames which are encoded into 64B/66B blocks as defined in clause 82 of [IEEE 802.3] for transport across the MTN. + +The MTNP layer provides channel forwarding, as described in clause 6.3.1 of [ITU-T G.800], for Ethernet MAC frames. + +The MTNP layer does not transfer client Ethernet MAC frame timing information. Any link status indication blocks (e.g., LF, RF, LPI) present on the UNI links are terminated by the UNI interface and are not transferred across the MTN layer networks. + +The only server layer defined for the MTNP is the MTNS. An instance of a MTNP layer network cannot be a client or server for another instance of a MTNP layer network. + +The only client defined for the MTNS layer is the MTNP layer. The MTNS layer provides fixed point to point connectivity for its MTNP layer clients at bitrates in multiples of ~5 Gb/s. The MTNS is based on Flex Ethernet (FlexE) as defined in [OIF FLEXE IA]. + +The server layer for the MTNS layer is provided by any of the Ethernet physical layers that use the encoding defined in clause 82 of [IEEE 802.3]. The Ethernet interfaces defined at the time this Recommendation was published are: 50GBASE-R, 100GBASE-R, 200GBASE-R and 400GBASE-R [IEEE 802.3]. + +The MTNS characteristic information (CI) is adapted to a modulator input by the lower functions of the physical coding sublayer (PCS) defined in clause 82 of [IEEE 802.3], the physical medium attachment (PMA) defined in clause 83 of [IEEE 802.3] and corresponding physical medium dependent (PMDs) of [IEEE 802.3]. The processing includes; scrambling, lane distribution, insertion of alignment markers, forward error correction (FEC) (except for some 100GBASE-R interfaces) and mapping to one or more digital lanes for modulation. + +Annex A provides a description of the relationship between the MTN layer networks and Ethernet [IEEE 802.3] and FlexE [OIF FLEXE IA]. + +The MTN digital layers are described in clause 7, the MTN optical media network is described in clause 8. + +# 7 MTN digital layer networks + +The client/server associations of the MTN digital layers are shown in Figure 7-1. + +![Figure 7-1: Client/server layer associations of the MTN digital layer networks. The diagram shows two vertical stacks of network layers. The top stack represents the MTNP layer network, starting with an MTNP/ETH_A source/sink at the top, connected via an MTNP AP to an MTNP_TT source/sink. This is connected via an MTNP network connection to an MTNP FwEP, which is then connected to an MTNS/MTNP_A source/sink. The bottom stack represents the MTNS layer network, starting with an MTNS/MTNP_A source/sink at the top, connected via an MTNS AP to an MTNS_TT source/sink. This is connected via an MTNS network connection to an MTNS FwEP. Vertical double-headed arrows on the left indicate the MTNP layer network and MTNS layer network boundaries. Horizontal dashed lines represent trails and network connections between corresponding entities in the two stacks. The diagram is labeled G.8310(20)_F7-1 at the bottom right.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Figure 7-1: Client/server layer associations of the MTN digital layer networks. The diagram shows two vertical stacks of network layers. The top stack represents the MTNP layer network, starting with an MTNP/ETH\_A source/sink at the top, connected via an MTNP AP to an MTNP\_TT source/sink. This is connected via an MTNP network connection to an MTNP FwEP, which is then connected to an MTNS/MTNP\_A source/sink. The bottom stack represents the MTNS layer network, starting with an MTNS/MTNP\_A source/sink at the top, connected via an MTNS AP to an MTNS\_TT source/sink. This is connected via an MTNS network connection to an MTNS FwEP. Vertical double-headed arrows on the left indicate the MTNP layer network and MTNS layer network boundaries. Horizontal dashed lines represent trails and network connections between corresponding entities in the two stacks. The diagram is labeled G.8310(20)\_F7-1 at the bottom right. + +**Figure 7-1 – Client/server layer associations of the MTN digital layer networks** + +## 7.1 MTNP layer network + +The MTNP layer network provides a MTNP trail transport entity to support the transport of Ethernet MAC frames across the MTN. The MTNP trail is supported by zero or more MTNS trail(s) as shown in Figures 7-2 and 7-3. The MTNS trail is described in clause 7.2. The MTNP trail transport entity supports only bidirectional, symmetrical, point to point connectivity. The description of the supported client layer network is outside the scope of this Recommendation. + +The MTNP trail transport entity provides channel forwarding, as described in clause 6.3.1 of [ITU-T G.800], for the client Ethernet MAC frames. + +The MTNP layer network provides configurable connectivity between path forwarding end points (FwEPs), or between a path FwEP and a path FP or between path FPs. + +The MTNP layer network is non-recursive i.e., a MTNP layer cannot be a client of another MTNP layer network. The only server layer for the MTNP layer is the MTNS layer described in clause 7.2. + +The CI of a MTNP layer network is a sequence of 64B/66B blocks encoded as defined in clause 82 of [IEEE 802.3] and is composed of: + +- A contiguous sequence of 64B/66B blocks that carry a MAC frame (called a packet) with a minimum gap between packets (called the inter-packet gap (IPG)). +- MTNP overhead encoded into 64B/66B blocks. + +The duration of the IPG can be modified to provide rate adaptation between the client MAC frames and the MTNP. Therefore, the MTNP layer network does not transfer client timing information. Also, any link status indications blocks (e.g., LF, RF, LPI) present on the UNI links are terminated by the UNI interface and are not transferred across the MTN layer networks. + +Details of the format of the MTNP CI are provided in [ITU-T G.8312]. + +To provide end-to-end networking, the following capabilities are included in the MTNP layer network: + +- MTNP connection rearrangement for flexible network routing; +- MTNP overhead processes to verify the integrity of the client adapted information (AI); +- MTNP operations, administration and maintenance functions, including network survivability. + +The MTNP layer network, shown in Figure 7-2, contains the transport processing functions, transport entities, and topological components described in clauses 7.1.1, 7.1.2 and 7.1.3 respectively. The interlayer adaptation functions are described in clause 7.3.1. + +![Figure 7-2: MTNP layer network diagram showing a path from an MTNP AP through an MTNP TT source, MTNP FwEP, MTNP SNC, MTNP FP, MTNP link connection, MTNP SNC, MTNP FP, MTNP link connection, MTNP SNC, MTNP FP, MTNP FwEP, MTNP TT sink, and MTNP AP. The path is labeled MTNP trail and MTNP network connection. The diagram is labeled G.8310(20)_F7-2.](27b06ec9f42b5d727a2630f61a5f1861_img.jpg) + +The diagram illustrates the MTNP layer network architecture. At the top, two MTNP AP (Access Point) icons are connected by a dashed line labeled "MTNP trail". Below each MTNP AP is an MTNP TT (Transport Terminal) icon, labeled "MTNP TT source" on the left and "MTNP TT sink" on the right. Each MTNP TT is connected to an MTNP FwEP (Forwarding Edge Point) icon. The MTNP FwEP icons are connected by a dashed line labeled "MTNP network connection". Below each MTNP FwEP is an MTNP SNC (Segment Connection) icon. Each MTNP SNC is connected to an MTNP FP (Forwarding Point) icon. The MTNP FP icons are connected by a solid line labeled "MTNP link connection". The MTNP link connections are connected to another MTNP SNC icon. Each MTNP SNC icon is connected to an MTNP FP icon. The MTNP FP icons are connected to an MTNP subnetwork, represented by a blue arrow pointing upwards. The diagram is labeled "G.8310(20)\_F7-2" in the bottom right corner. + +Figure 7-2: MTNP layer network diagram showing a path from an MTNP AP through an MTNP TT source, MTNP FwEP, MTNP SNC, MTNP FP, MTNP link connection, MTNP SNC, MTNP FP, MTNP link connection, MTNP SNC, MTNP FP, MTNP FwEP, MTNP TT sink, and MTNP AP. The path is labeled MTNP trail and MTNP network connection. The diagram is labeled G.8310(20)\_F7-2. + +**Figure 7-2 – MTNP layer network** + +As described in [ITU-T G.800], the MTNP subnetwork may represent the aggregation of contained subnetworks and links or, it may represent the limit of subnetwork recursion which is a matrix. + +A MTNP subnetwork may provide a subnetwork connection directly between MTNP FwEPs without adaptation to an MTN section layer. This is illustrated in Figure 7-3. + +![Figure 7-3: MTNP subnetwork example diagram showing a path from an MTNP AP through an MTNP TT source, MTNP FwEP, MTNP SNC, MTNP FwEP, MTNP TT sink, and MTNP AP. The path is labeled MTNP trail and MTNP network connection. The diagram is labeled G.8310(20)_F7-3.](853f59c89931a666c07903b31d098277_img.jpg) + +The diagram illustrates an MTNP subnetwork example. At the top, two MTNP AP (Access Point) icons are connected by a dashed line labeled "MTNP trail". Below each MTNP AP is an MTNP TT (Transport Terminal) icon, labeled "MTNP TT source" on the left and "MTNP TT sink" on the right. Each MTNP TT is connected to an MTNP FwEP (Forwarding Edge Point) icon. The MTNP FwEP icons are connected by a dashed line labeled "MTNP network connection". Below the MTNP FwEP icons is an MTNP SNC (Segment Connection) icon. The MTNP SNC icon is connected to an MTNP subnetwork, represented by a blue arrow pointing upwards. The diagram is labeled "G.8310(20)\_F7-3" in the bottom right corner. + +Figure 7-3: MTNP subnetwork example diagram showing a path from an MTNP AP through an MTNP TT source, MTNP FwEP, MTNP SNC, MTNP FwEP, MTNP TT sink, and MTNP AP. The path is labeled MTNP trail and MTNP network connection. The diagram is labeled G.8310(20)\_F7-3. + +**Figure 7-3 – MTNP subnetwork example** + +### 7.1.1 MTNP trail termination + +The following generic processes are assigned to the MTNP trail termination: + +- validation of connectivity integrity; +- assessment of transmission quality; +- transmission defect detection and indication. + +The requirements for these processes are outlined in clause 9. + +There are three types of MTNP trail termination: + +- MTNP bidirectional trail termination: consists of a pair of collocated MTNP trail termination source and sink functions; +- MTNP trail termination source: accepts AI from a client layer network at its input, generates and inserts the MTNP trail overhead as a separate and distinct logical data stream and presents the CI of the MTNP layer network at its output; +- MTNP trail termination sink: accepts the CI of the MTNP layer network at its input, extracts and processes the separate and distinct logical data stream containing the MTNP trail overhead and presents the AI at its output. + +### 7.1.2 MTNP transport entities + +Network connections, subnetwork connections, link connections and trails are as described in [ITU-T G.800]. Tandem connections are not supported. + +### 7.1.3 MTNP topological components + +Layer network, subnetworks, links and access groups are as described in [ITU-T G.800]. + +The MTNP subnetwork provides configurable subnetwork connections between an input forwarding point (FP) or forwarding end point (FwEP) and an output FP or FwEP. + +## 7.2 MTNS layer + +The MTNS layer network provides a fixed point-to-point MTNS trail transport entity, that is bidirectional and symmetrical to support the transport of the MTNP client. The MTNS trail is supported by an optical signal tributary group (OTSiG). The OTSiG is implemented by one or more Ethernet optical interfaces as described in clause 8.2. + +The MTNS layer network is non-recursive and the only client for the MTNS layer network is the MTNP layer network. + +The CI of an MTNS layer network is a stream of 64B/66B blocks encoded as defined in clause 82 of [IEEE 802.3] and is composed of: + +- Client MTNP CI; and +- MTNS overhead encoded into 64B/66B blocks. + +The format of the MTNS is based on FlexE that is defined in [OIF FLEXE IA], details of the format are provided in [ITU-T G.8312]. The MTNS is structured as a set of calendar slots each with a capacity of ~5Gbit/s. The number of calendar slots supported by the MTNS is dependent on the OTSiG that supports the MTNS. A MTNP client is allocated one or more calendar slots. + +The duration of the IPG (in the MTNP CI) can be modified by adding or removing 64B/66B blocks (in the IPG) to provide rate adaptation between the MTNP CI and the calendar slots allocated to it in the MTNS. + +The capabilities of the MTNS layer network include: + +- MTNS overhead processes to confirm the integrity of the client AI and conditioning for its transport over an OTSiG; +- MTNS operations, administration and maintenance functions. + +The MTNS layer network, shown in Figure 7-4 contains the transport processing functions, transport entities, and topological components described in clauses 7.2.1, 7.2.2 and 7.2.3 respectively. The interlayer adaptation functions are described in clause 7.3.2. + +![Diagram of the MTNS layer network showing the flow from MTNS TT source to MTNS TT sink through MTNS AP, MTNS network connection, and MTNS link connection components.](a33da0f14e456f92539ce3e9b7d81f9a_img.jpg) + +The diagram illustrates the MTNS layer network architecture. On the left, an 'MTNS TT source' (represented by a downward-pointing triangle) is connected to an 'MTNS AP' (represented by a circle with two internal nodes). The 'MTNS AP' is connected to an 'MTNS network connection' (represented by a dashed line). This connection leads to another 'MTNS AP' on the right, which is then connected to an 'MTNS TT sink' (represented by an upward-pointing triangle). Below the 'MTNS network connection' is an 'MTNS link connection' (represented by a solid line). The entire diagram is labeled 'G.8310(20)\_F7-4' at the bottom right. + +Diagram of the MTNS layer network showing the flow from MTNS TT source to MTNS TT sink through MTNS AP, MTNS network connection, and MTNS link connection components. + +**Figure 7-4 – MTNS layer network** + +The MTNS network connection is supported by an OTSiG as described in clause 8.2. + +### 7.2.1 MTNS trail termination + +The following generic processes are assigned to the MTNS trail termination: + +- Validation of connectivity integrity. + +The requirements for these processes are outlined in clause 9. + +There are three types of MTNS trail termination: + +- MTNS bidirectional trail termination: consists of a pair of collocated MTNS trail termination source and sink functions; +- MTNS trail termination source: accepts AI from the MTNP client layer network at its input, generates and inserts the MTNS trail overhead as a separate and distinct logical data stream and presents the CI of the MTNS layer network at its output. If bonding is supported (see clause 8.2.2) it inverse multiplexes the client AI onto a group of homogenous Ethernet interfaces; +- MTNS trail termination sink: accepts the CI of the MTNS layer network at its input, extracts and processes the separate and distinct logical data stream containing the MTNS trail overhead and presents the MTNP AI at its output. If bonding is supported (see clause 8.2.2) it accepts the input from a group Ethernet interfaces, aligns the members of the group and reconstructs the payload at the aggregate line rate. + +### 7.2.2 MTNS transport entities + +Network connections, link connections and trails are as described in [ITU-T G.800]. Subnetwork connections and tandem connections are not supported. + +### 7.2.3 MTNS topological components + +Layer network and access groups are as described in [ITU-T G.800]. Subnetworks are not supported. + +## **7.3 Client/server associations** + +### **7.3.1 MTNP/Ethernet MAC frame (ETH) adaptation** + +The bidirectional MTNP/ETH adaptation function is performed by a collocated pair of source and sink MTNP/ETH adaptation functions. + +The MTNP/ETH adaptation source performs the following processes between its input and its output: + +- all the processing required to encode the client MAC frame into a contiguous sequence of 64B/66B blocks as defined in clauses 81 and 82 of [IEEE 802.3]; +- generation of management/maintenance signals as described in clause 9. + +The MTNP/ETH adaptation sink performs the following processes between its input and its output: + +- recovery of the client MAC frames from the contiguous sequence of 64B/66B blocks as defined in clauses 81 and 82 of [IEEE 802.3]; +- termination of management/maintenance signals as described in clause 9. + +### **7.3.2 MTNS/MTNP adaptation** + +The bidirectional MTNS/MTNP adaptation function is performed by a collocated pair of source and sink MTNS/MTNP adaptation functions. + +The MTNS/MTNP adaptation source performs the following processes between its input and its output: + +- all the processing required to map 664B/66B blocks of the MTNP CI into a defined number of calendar slots; +- generation and termination of relevant management/maintenance signals as described in clause 9. + +The MTNS/MTNP adaptation sink performs the following processes between its input and its output: + +- recovery of the MTNP CI from the assigned calendar slots; +- generation and termination of management/maintenance signals as described in clause 9. + +# **8 Architecture of the media network supporting the MTN** + +The architecture of the media network, defined in [IEEE 802.3], is described using the media constructs listed in clause 8.1 to represent the different functions that are present in the media network. Media constructs operate on the signal envelope (e.g., constrain or direct the media channel, etc.) and are not aware of the information being carried. Media constructs do not modulate or demodulate the signal and therefore do not process the digital information that is carried by the signal. + +A full description of the generic functional architecture of the media network is provided in [ITU-T G.807]. + +The media network that support the MTNS only provides fixed point to point media associations and does not support the optical signal maintenance entity (OSME) described in [ITU-T G.807]. + +## **8.1 Media constructs** + +The following media constructs used to describe the architecture of the media network are described in [ITU-T G.807]: + +- media port; +- media channel; + +- media channel group; +- fibre. + +## 8.2 Optical tributary signal group (OTSiG) + +The MTNS is supported by an OTSiG. The OTSiG is a management/control abstraction that represents a group of one or more optical tributary signals (OTSi), see [ITU-T G.807]. The OTSiG consists of one or more Ethernet physical layer interfaces defined in [IEEE 802.3]. Each unidirectional optical tributary signal (OTSi) is carried in an independent network media channel (NMC). The NMC is described in clause 7.1.2.1 of [ITU-T G.807]. The digital information stream from the MTNS present at the FwEP is mapped and encoded by an adaptation source function. + +NOTE – The encoding process in the M-AI/MTNS adaptation may include the computation and insertion of a forward error correction (FEC) code. + +The resultant modulator adapted information (M-AI) is used by a modulator source to create an OTSi. The OTSi is converted back to M-AI by a demodulator sink according to a specific modulation/demodulation mechanism. The adaptation sink function processes the M-AI to recreate the MTNS digital information stream. As illustrated in Figure 8-2, the MTNS client may be carried by more than one OTSi (depending on the particular Ethernet interface that is used). The functional models for these interfaces are provided in Figures 8-1 and 8-2. Note that in most Ethernet interfaces the modulators and filters are not configurable. + +At the time of publication of this Recommendation the Ethernet interfaces, defined in [IEEE 802.3], that can be used in the MTN media network are: 50GBASE-R, 100GBASE-R, 200GBASE-R and 400GBASE-R. + +### 8.2.1 MTNS carried over a single Ethernet interface + +The case where the MTNS is carried by one Ethernet interface that uses a single OTSi is shown in Figure 8-1. The OTSi is carried from the media port on the modulator source to the media port on the demodulator sink by a network media channel (NMC). + +![Figure 8-1: Mapping an MTNS to an OTSiG that contains one OTSi. The diagram shows a vertical stack of components. At the top is a triangle labeled 'MTNS'. Below it is a circle with two arrows pointing towards it, labeled 'FwEP' on the left and 'MTNS CI' on the right. Below the circle is a trapezoid labeled 'M-AI/MTNS'. Below this is a square labeled 'M'. To the left of the 'M' square is an arrow labeled 'M-AI' and 'Modulator adapted information'. To the right of the 'M' square is an arrow labeled 'M-AP' and 'Modulator access point'. Below the 'M' square is a dashed circle labeled 'OTSiG'. Below that is a solid circle labeled 'OTSi'. Below that is a horizontal line labeled 'Media port'. Below the media port is a horizontal line labeled 'NMC'. To the right of the 'NMC' line is a dashed circle labeled 'NMCG'. At the bottom right is the text 'G.8310(20)_F8-1'.](b90144cfbb81a2d610d920240fda689d_img.jpg) + +Figure 8-1: Mapping an MTNS to an OTSiG that contains one OTSi. The diagram shows a vertical stack of components. At the top is a triangle labeled 'MTNS'. Below it is a circle with two arrows pointing towards it, labeled 'FwEP' on the left and 'MTNS CI' on the right. Below the circle is a trapezoid labeled 'M-AI/MTNS'. Below this is a square labeled 'M'. To the left of the 'M' square is an arrow labeled 'M-AI' and 'Modulator adapted information'. To the right of the 'M' square is an arrow labeled 'M-AP' and 'Modulator access point'. Below the 'M' square is a dashed circle labeled 'OTSiG'. Below that is a solid circle labeled 'OTSi'. Below that is a horizontal line labeled 'Media port'. Below the media port is a horizontal line labeled 'NMC'. To the right of the 'NMC' line is a dashed circle labeled 'NMCG'. At the bottom right is the text 'G.8310(20)\_F8-1'. + +**Figure 8-1 – Mapping an MTNS to an OTSiG that contains one OTSi** + +The case where an MTNS is carried by one Ethernet interface that uses more than one OTSi is illustrated in Figure 8-2. + +![Diagram illustrating the mapping of an MTNS to an OTSiG that contains more than one OTSi. The diagram shows the flow from an MTNS (triangle) through FwEP and MTNS CI to an M-AI/MTNS block. Below this, multiple instances of M-AI are shown, with one instance connected to an M block. The M block is connected to an OTSiG, which is further connected to an OTSi. The OTSi is connected to a Media port, which is part of an NMC. The NMC is connected to an NMCG. The diagram is labeled G.8310(20)_F8-2.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +The diagram illustrates the mapping of an MTNS to an OTSiG that contains more than one OTSi. At the top, an MTNS (triangle) is connected to a FwEP (Forwarding Entity Point) and an MTNS CI (Control Interface). Below this, an M-AI/MTNS block is shown. Multiple instances of M-AI are connected to this block, with one instance connected to an M block. The M block is connected to an OTSiG, which is further connected to an OTSi. The OTSi is connected to a Media port, which is part of an NMC. The NMC is connected to an NMCG. The diagram is labeled G.8310(20)\_F8-2. + +Diagram illustrating the mapping of an MTNS to an OTSiG that contains more than one OTSi. The diagram shows the flow from an MTNS (triangle) through FwEP and MTNS CI to an M-AI/MTNS block. Below this, multiple instances of M-AI are shown, with one instance connected to an M block. The M block is connected to an OTSiG, which is further connected to an OTSi. The OTSi is connected to a Media port, which is part of an NMC. The NMC is connected to an NMCG. The diagram is labeled G.8310(20)\_F8-2. + +**Figure 8-2 – Mapping an MTNS to an OTSiG that contains more than one OTSi** + +The differential delay between members of the OTSiG must be controlled, this is represented by placing all of the NMCs in a single NMC group (NMCG). Normally these functions are supported by an Ethernet interface and all members of the OTSiG are carried over the same fibre. + +### 8.2.2 MTNS carried over more than one Ethernet interface + +The MTNS may be carried by a group of two or more Ethernet interfaces. In the description of FlexE in [OIF FLEXE IA] this is referred to as bonding. This is modelled by expanding the MTNS trail termination to provide an inverse multiplexing sub-layer as described in clause 5.3.3.1.2 of [ITU-T G.805]. This is shown in Figure 8-3, in this example each Ethernet interface is supported by a single OTSi. Each of the Ethernet interfaces may be supported by more than one OTSi as shown in Figure 8-2. + +![Figure 8-3: Mapping an MTNS to a set of bonded Ethernet interfaces. The diagram shows a top-down view of the MTNS TT (Transport Terminal) at the top, which contains an 'Inverse multiplexing sublayer'. Below this, the signal is split into two parallel paths. Each path contains an 'M-AI/MTNS' adaptation block, followed by an 'M' (Media) block. The 'M' blocks are connected to 'OTSiG' and 'OTSi' layers. The signals then pass through 'Media port' blocks and are combined into a single 'NMC' (Network Medium Concatenation) layer, which is further divided into 'NMCG' (Network Medium Concatenation Group) layers. The diagram is labeled 'G.8310(20)_F8-3' at the bottom right.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Figure 8-3: Mapping an MTNS to a set of bonded Ethernet interfaces. The diagram shows a top-down view of the MTNS TT (Transport Terminal) at the top, which contains an 'Inverse multiplexing sublayer'. Below this, the signal is split into two parallel paths. Each path contains an 'M-AI/MTNS' adaptation block, followed by an 'M' (Media) block. The 'M' blocks are connected to 'OTSiG' and 'OTSi' layers. The signals then pass through 'Media port' blocks and are combined into a single 'NMC' (Network Medium Concatenation) layer, which is further divided into 'NMCG' (Network Medium Concatenation Group) layers. The diagram is labeled 'G.8310(20)\_F8-3' at the bottom right. + +**Figure 8-3 – Mapping an MTNS to a set of bonded Ethernet interfaces** + +In this case the OTSi that supports each of the Ethernet interfaces is in the same OTSiG and the differential delay of the members of the OTSiG must be constrained. + +## 8.3 Client/server associations + +### 8.3.1 M-AI/MTNS adaptation + +The bidirectional M-AI/MTNS adaptation function is performed by a collocated pair of source and sink M-AI/MTNS adaptation functions. + +The M-AI/MTNS adaptation source performs the following processes between its input and its output: + +- all the processing required to encode and map the MTNS client into one or more instances of M-AI. These processes include scrambling, lane distribution, insertion of alignment markers, forward error correction (FEC), PMA and physical medium dependent (PMD) sublayers. FEC is required on all Ethernet interfaces except for some legacy 100GBASE-R Ethernet interfaces. These processes are described in [IEEE 802.3]. + +The M-AI/MTNS adaptation sink performs the following processes between its input and its output: + +- All the processes necessary to recover the MTNS client from one or more instances of M-AI. These processes are described in [IEEE 803.3]. +- If the Ethernet interface uses FEC: + - ensure that all blocks in an uncorrectable FEC codeword are error marked; + - replace all 64B/66B blocks with an invalid sync header with a /E/ block. + +# **9 Management capabilities** + +This clause provides an overview of the fault, performance and configuration management capabilities provided by the MTN. The capabilities are described in [ITU-T G.8312]. + +NOTE – Further details will be provided in the MTN equipment Recommendation. + +The MTN digital layers (MTNP, MTNS) use digital overhead to provide OAM, which can report on the status of the layer and may be used to infer the status of the server layer. + +The media network that is deployed as a part of an MTN network uses point-to-point Ethernet links and is not expected to support fault, performance and configuration management. + +## **9.1 Capabilities** + +### **9.1.1 Fault, configuration and performance management** + +The MTNP layer network provides the capabilities to: + +- configure the interconnection of reference points e.g., FPs, FwEPs; +- detect faults and initiate recovery actions where applicable; +- support single-ended maintenance; +- detect and report misconnections; +- detect performance degradation and verify quality of service. + +The MTNS layer network provides the capabilities to: + +- interconnect the FwEP reference points; +- detect faults; +- support single-ended maintenance; +- detect and report misconnections. + +### **9.1.2 Client/server interaction** + +The server detects and indicates to the client layer when a digital stream or optical signal is not present. + +To avoid unnecessary, inefficient or conflicting survivability actions, escalation strategies (e.g., introduction of hold-off times and alarm suppression methods) may be required: + +- within a layer; +- between a server and client layer. + +### **9.1.3 Adaptation management** + +Adaptation management refers to the set of processes for managing the adaptation of a client layer network to/from the server layer network. + +### **9.1.4 Connection supervision** + +#### **9.1.4.1 Continuity supervision** + +Continuity supervision refers to the set of processes for monitoring the continuity of a transport entity (e.g., trail). + +In general, a continuity fault in a server is indicated to a client through server signal fail (SSF) indication. + +#### **9.1.4.2 Connectivity supervision** + +Connectivity supervision refers to the set of processes for monitoring the integrity of the routing of a connection between the source and sink trail terminations. + +Connectivity supervision is necessary to confirm proper routing of a connection between trail termination source and sink during the connection set-up process. Furthermore, connectivity supervision is needed to ensure that connectivity is maintained while the connection is active. + +Trail trace identifier (TTI) is necessary to ensure that the signal received by a trail termination sink originates from the intended trail termination source: + +- TTI is provided by the trail transport entity for the MTNS layer to ensure proper MTNS layer connections. +- TTI is provided by the trail transport entity for the MTNP layer to ensure proper MTNP layer connections. + +#### **9.1.4.3 Maintenance information** + +Maintenance information refers to the set of processes for indicating defects in a connection, which is part of a trail. The defect indications are given in the downstream and upstream directions of a bidirectional trail. + +The capabilities are described in [ITU-T G.8312]. + +NOTE – Further details will be provided in the MTN equipment Recommendation. + +Two maintenance information processes are identified for the digital layers: + +- alarm indication signal (AIS); +- open connection indication (OCI). + +These processes enable defect localization and single-ended maintenance. + +### **9.1.5 Connection quality supervision** + +Connection quality supervision refers to the set of processes for monitoring the performance of a connection. Generic processes include parameter measurement, collection, filtering and processing. Connection quality supervision is supported for the MTNP layer network. Delay measurement is also supported by the MTNP layer. + +### **9.1.6 Management communications** + +Management communications are transported via an embedded communication channel as specified in [ITU-T G.7712]. The MTNS provides a management communications channel (MCC), the MTNP does not support management communications. + +### **9.1.7 Frequency and time synchronization** + +The communication of time and frequency information using either precision time protocol (PTP) as defined in [b-ITU-T G.8265.1] or in [b-ITU-T G.8275.1] or synchronization status message (SSM) as defined in [b-ITU-T G.8264] may be supported by the MTNS (using the FlexE synchronization messaging channel). + +## **9.2 Connection supervision techniques** + +Connection supervision is the process of monitoring the integrity of a given connection in the digital layers of the MTN. The integrity may be verified by means of detecting and reporting connectivity and transmission performance defects for a given connection. Only inherent monitoring defined in [ITU-T G.805] is supported. + +## **9.3 Connection supervision applications** + +### **9.3.1 Unused connections** + +In order to detect the inadvertent opening of a MTNP subnetwork connection a distinct replacement signal (open connection indication (OCI)) is used. + +### **9.3.2 Connection monitoring** + +Only the MTNP and MTNS trail transport entities are monitored. + +# **10 Survivability techniques** + +It is expected that survivability techniques will only be used in the MTN for the trail transport entity in the MTNP layer network. It is only envisioned that 1+1 linear path protection as described in [ITU-T G.808.1] will be used. The MTNP overhead is used to detect faults or performance degradations (see clause 9) and these events may be used to trigger the replacement of the failed transport entity with a protection transport entity. Details of the mechanism are out of the scope of this Recommendation. + +# Annex A + +## Relationship of MTN to other technologies + +(This annex forms an integral part of this Recommendation.) + +Figure A.1 shows the relationship between the MTN layer networks, Ethernet as defined in [IEEE 802.3] and FlexE as defined in [OIF FLEXE IA]. + +The MTN path to Ethernet client adaptation is defined by reference to [IEEE 802.3]. The AI at the MTNP\_AP consists of a sequence of [IEEE 802.3] clause 82-compliant 64B/66B blocks. The adaptation of the MTN section to media is described by [IEEE 802.3]. The CI at the MTNS FwEP consists of a stream of [IEEE 802.3] clause 82-compliant 64B/66B blocks. The use of [IEEE 802.3] clause 82-compliant 64B/66B blocks allows the MTN section layer to be carried over Ethernet PHYs that use [IEEE 802.3] clause 82 PCS. Figure A.1 shows the relationship of MTN to [IEEE 802.3] and [OIF FLEXE IA] for the case where the Ethernet signal is carried by a single OTSi (see Figure 8-1) and bonding (described in clause 8.2.2) is not used. + +![Diagram showing the relationship of MTN to [IEEE 802.3] Ethernet and [OIF FLEXE IA] FlexE. The diagram is divided into three vertical columns: IEEE model, MTN layer networks, and OIF FlexE shim. The IEEE model column shows the standard Ethernet stack: MAC, RS (Clause 81), 64B/66B, PCS (Clause 82) sublayers (Scramble, Lane distribution, AM, Lower sublayers). The MTN layer networks column shows the MTN stack: Client clock domain, MTNP AP, MTNP FwEP, MTNP subnetwork, MTNP FP, MTNS AP, MTNS FwEP, M-AI/MTNS, M-AI AP, and M. The OIF FlexE shim column shows the OIF flex E shim. Vertical dashed lines indicate clock domains: Client clock domain, Local clock domain, and Line clock domain. Horizontal dashed lines separate the MTN path layer, MTN section layer, and MTN optical media layer. Arrows indicate data flow and adaptation points between the layers.](7d3d5fb5d09c0cd35a9d637be241651e_img.jpg) + +Diagram showing the relationship of MTN to [IEEE 802.3] Ethernet and [OIF FLEXE IA] FlexE. The diagram is divided into three vertical columns: IEEE model, MTN layer networks, and OIF FlexE shim. The IEEE model column shows the standard Ethernet stack: MAC, RS (Clause 81), 64B/66B, PCS (Clause 82) sublayers (Scramble, Lane distribution, AM, Lower sublayers). The MTN layer networks column shows the MTN stack: Client clock domain, MTNP AP, MTNP FwEP, MTNP subnetwork, MTNP FP, MTNS AP, MTNS FwEP, M-AI/MTNS, M-AI AP, and M. The OIF FlexE shim column shows the OIF flex E shim. Vertical dashed lines indicate clock domains: Client clock domain, Local clock domain, and Line clock domain. Horizontal dashed lines separate the MTN path layer, MTN section layer, and MTN optical media layer. Arrows indicate data flow and adaptation points between the layers. + +G.8310(20)\_FA.1 + +Figure A.1 – Relationship of MTN to [IEEE 802.3] Ethernet and [OIF FLEXE IA] FlexE + +## Bibliography + +- [b-ITU-T G.8264] Recommendation ITU-T G.8264/Y.1364 (2017), *Distribution of timing information through packet networks.* +- [b-ITU-T G.8265.1] Recommendation ITU-T G.8265.1/Y.1365.1 (2014), *Precision time protocol telecom profile for frequency synchronization.* +- [b-ITU-T G.8275.1] Recommendation ITU-T G.8275.1/Y.1369.1 (2020), *Precision time protocol telecom profile for phase/time synchronization with full timing support from the network.* + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.853.10-199903-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.853.10-199903-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..a7da83ecb82b51a4cef7694858eef2c35f1986ff --- /dev/null +++ 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0000000000000000000000000000000000000000..4d9304932d8a207c6d118287cbe8b8166dfb665d --- /dev/null +++ b/marked/G/T-REC-G.853.10-199903-I_PDF-E/acfc53eca625d62b38aa2563efa95c3e_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:73d4b4fbedc8ebb4a1a76f104b3a01faaa87b15f4b12e1f5b91df152677e5fb8 +size 118075 diff --git a/marked/G/T-REC-G.853.10-199903-I_PDF-E/raw.md b/marked/G/T-REC-G.853.10-199903-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..7d6d77e97f802979fb50a3bfff71ea5cbe3fe32b --- /dev/null +++ b/marked/G/T-REC-G.853.10-199903-I_PDF-E/raw.md @@ -0,0 +1,449 @@ + + +![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with the letters ITU and a lightning bolt. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.853.10** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(03/99) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – +Management of transport network + +--- + +**Information viewpoint for pre-provisioned link +connection management** + +ITU-T Recommendation G.853.10 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +# **INFORMATION VIEWPOINT FOR PRE-PROVISIONED LINK CONNECTION MANAGEMENT** + +## **Summary** + +The pre-provisioned link connection management community is used to assign transport entities (link connections or connection termination points) to a caller and to control and update the available capacity of the linking entity (link or link end) that contains the transport entities. The available capacity of the linking entity contains all the unassigned transport entities. This community should be used in the case where transport entities have already been provisioned inside the linking entity using the pre-provisioned adaptation management service (G.85x.8 series of Recommendations). + +The capability of having pre-provisioned transport entities is available in technologies such as SDH or WDM. + +### **Source** + +ITU-T Recommendation G.853.10 was prepared by ITU-T Study Group 4 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 26th of March 1999. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +### NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +###### Page + +| | | | +|------|--------------------------------------------------------------------|---| +| 1 | Scope ..... | 1 | +| 2 | References ..... | 1 | +| 3 | Definitions ..... | 1 | +| 4 | Abbreviations ..... | 1 | +| 5 | Conventions ..... | 2 | +| 6 | Class diagrams ..... | 2 | +| 6.1 | UML class diagram representing relationships between classes ..... | 2 | +| 6.2 | UML class diagram representing the Inheritance Hierarchy ..... | 3 | +| 7 | Label references ..... | 3 | +| 8 | Information object class definitions ..... | 4 | +| 8.1 | plcmLayerNetworkDomain ..... | 4 | +| 8.2 | plcmLink ..... | 4 | +| 8.3 | plcmLinkConnection ..... | 4 | +| 8.4 | plcmLinkEnd ..... | 5 | +| 8.5 | plcmNetworkCTP ..... | 5 | +| 9 | Information relationship definitions ..... | 5 | +| 10 | Static schemas ..... | 5 | +| 11 | Dynamic schemas ..... | 5 | +| 12 | Attributes ..... | 6 | +| 12.1 | plcmCallerId ..... | 6 | + + + +###### Recommendation G.853.10 + +# INFORMATION VIEWPOINT FOR PRE-PROVISIONED LINK CONNECTION MANAGEMENT + +(Geneva, 1999) + +# 1 Scope + +This information viewpoint specification is related to the pre-provisioned link connection management enterprise specification defined in Recommendation G.852.10. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.851.1 (1996), *Management of the transport network – Application of the RM-ODP framework.* +- [2] ITU-T Recommendation G.853.1 (1999), *Common elements of the information viewpoint for the management of a transport network.* +- [3] ITU-T Recommendation G.852.10 (1999), *Enterprise viewpoint for pre-provisioned link connection management.* +- [4] ITU-T Recommendation G.854.10 (1999), *Computational viewpoint for pre-provisioned link connection management.* + +# 3 Definitions + +None. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations. + +| | | +|--------|-------------------------------------------------| +| CTP | Connection Termination Point | +| Id | Identifier | +| imp | imported | +| LC | Link Connection | +| LE | Link End | +| LND | Layer Network Domain | +| pam | pre-provisioned adaptation management | +| plcm | pre-provisioned link connection management | +| RM-ODP | Reference Model for Open Distributed Processing | +| UML | Unified Modelling Language | + +# 5 Conventions + +None. + +# 6 Class diagrams + +## 6.1 UML class diagram representing relationships between classes + +![UML class diagram showing relationships between plcLayerNetworkDomain, plcLink, plcLinkEnd, plcLinkConnection, and plcNetworkCTP.](35a7554182eb055209552843f341a1ae_img.jpg) + +``` +classDiagram + class plcLayerNetworkDomain + class plcLink + class plcLinkEnd + class plcLinkConnection + class plcNetworkCTP + + plcLink --|> plcLayerNetworkDomain : containerLND (1..1) layerNetworkDomain IsMadeOf element (1..N) + plcLinkEnd --|> plcLayerNetworkDomain : containerLND (1..1) layerNetworkDomain IsMadeOf element (1..N) + plcLinkConnection --|> plcLink : containerLink (1..1) linkHasLinkConnections elementLC (1..N) + plcLinkConnection --|> plcNetworkCTP : element (1..N) + plcLinkEnd --|> plcNetworkCTP : containerLE (1..1) linkEndHasNetworkCTPs elementCTP (1..N) +``` + +The diagram illustrates the following classes and their relationships: + +- plcLayerNetworkDomain**: The base class for network domains. +- plcLink**: A class representing a network link. It has a generalization relationship with **plcLayerNetworkDomain** (labeled *containerLND* (1..1) *layerNetworkDomain IsMadeOf* *element* (1..N)). +- plcLinkEnd**: A class representing an end of a network link. It also has a generalization relationship with **plcLayerNetworkDomain** (labeled *containerLND* (1..1) *layerNetworkDomain IsMadeOf* *element* (1..N)). +- plcLinkConnection**: A class representing a connection between two links. It has a generalization relationship with **plcLink** (labeled *containerLink* (1..1) *linkHasLinkConnections* *elementLC* (1..N)) and with **plcNetworkCTP** (labeled *element* (1..N)). +- plcNetworkCTP**: A class representing a network control point. It has a generalization relationship with **plcLinkEnd** (labeled *containerLE* (1..1) *linkEndHasNetworkCTPs* *elementCTP* (1..N)). + +T0410780-99 + +UML class diagram showing relationships between plcLayerNetworkDomain, plcLink, plcLinkEnd, plcLinkConnection, and plcNetworkCTP. + +Figure 1/G.853.10 – UML class diagram with relationships between classes + +## 6.2 UML class diagram representing the Inheritance Hierarchy + +![UML class diagram showing inheritance hierarchy for G.853.1 classes. Root: G.853.1: networkInformationTop (resourceId). Subclasses: G.853.1: transportConnection (signalIdentification, directionality), G.853.1: networkCTP (signalIdentification, pointDirectionality), G.853.1: link (signalIdentification, linkDirectionality), G.853.1: linkEnd (signalIdentification, topologicalEndDirection). Further subclasses include G.853.1: linkConnection, plcmNetworkCTP (userLabel (imp), plcmCallerId), plcmLink (pamAvailableLinkCapacity (imp)), plcmLinkEnd (pamAvailableLinkCapacity (imp)). G.853.1: layerNetworkDomain (signalIdentification) is also shown with plcmLayerNetworkDomain subclass. T0410790-99](acfc53eca625d62b38aa2563efa95c3e_img.jpg) + +``` + +classDiagram + class G853_1_networkInformationTop["G.853.1: networkInformationTop"] { + resourceId + } + class G853_1_transportConnection["G.853.1: transportConnection"] { + signalIdentification + directionality + } + class G853_1_networkCTP["G.853.1: networkCTP"] { + signalIdentification + pointDirectionality + } + class G853_1_link["G.853.1: link"] { + signalIdentification + linkDirectionality + } + class G853_1_linkEnd["G.853.1: linkEnd"] { + signalIdentification + topologicalEndDirection + } + class G853_1_linkConnection["G.853.1: linkConnection"] + class plcmNetworkCTP["plcmNetworkCTP"] { + G.853.1: userLabel (imp) + plcmCallerId + } + class plcmLink["plcmLink"] { + pamAvailableLinkCapacity (imp) + } + class plcmLinkEnd["plcmLinkEnd"] { + pamAvailableLinkCapacity (imp) + } + class G853_1_layerNetworkDomain["G.853.1: layerNetworkDomain"] { + signalIdentification + } + class plcmLayerNetworkDomain["plcmLayerNetworkDomain"] + class plcmLinkConnection["plcmLinkConnection"] { + G.853.1: userLabel (imp) + plcmCallerId + } + + G853_1_transportConnection --|> G853_1_networkInformationTop + G853_1_networkCTP --|> G853_1_networkInformationTop + G853_1_link --|> G853_1_networkInformationTop + G853_1_linkEnd --|> G853_1_networkInformationTop + G853_1_linkConnection --|> G853_1_transportConnection + plcmNetworkCTP --|> G853_1_networkCTP + plcmLink --|> G853_1_link + plcmLinkEnd --|> G853_1_linkEnd + plcmLinkConnection --|> G853_1_linkConnection + plcmLayerNetworkDomain --|> G853_1_layerNetworkDomain + +``` + +UML class diagram showing inheritance hierarchy for G.853.1 classes. Root: G.853.1: networkInformationTop (resourceId). Subclasses: G.853.1: transportConnection (signalIdentification, directionality), G.853.1: networkCTP (signalIdentification, pointDirectionality), G.853.1: link (signalIdentification, linkDirectionality), G.853.1: linkEnd (signalIdentification, topologicalEndDirection). Further subclasses include G.853.1: linkConnection, plcmNetworkCTP (userLabel (imp), plcmCallerId), plcmLink (pamAvailableLinkCapacity (imp)), plcmLinkEnd (pamAvailableLinkCapacity (imp)). G.853.1: layerNetworkDomain (signalIdentification) is also shown with plcmLayerNetworkDomain subclass. T0410790-99 + +Figure 2/G.853.10 – UML class diagram representing the Inheritance Hierarchy + +# 7 Label references + +| Full label reference | Local label reference | +|------------------------------------------------------------------------|----------------------------| +| <"Rec. G.853.1", INFORMATION_OBJECT: layerNetworkDomain> | layerNetworkDomain | +| <"Rec. G.853.1", INFORMATION_OBJECT: link> | link | +| <"Rec. G.853.1", INFORMATION_OBJECT: linkConnection> | linkConnection | +| <"Rec. G.853.1", INFORMATION_OBJECT: linkEnd> | linkEnd | +| <"Rec. G.853.1", INFORMATION_OBJECT: networkCTP> | networkCTP | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: layerNetworkDomainIsMadeOf> | layerNetworkDomainIsMadeOf | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkHasLinkConnections> | linkHasLinkConnections | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkEndHasNetworkCTPs> | linkEndHasNetworkCTPs | +| <"Rec. G.853.8", ATTRIBUTE: pamAvailableLinkCapacity> | pamAvailableLinkCapacity | +| <"Rec. G.853.1", ATTRIBUTE: userLabel> | userLabel | + +# 8 Information object class definitions + +## 8.1 plcmlayerNetworkDomain + + + +#### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + +-- none additional + +#### RELATIONSHIP + + + +## 8.2 plcmlink + + + +#### DEFINITION + +"This object class is derived from ." + +#### ATTRIBUTE + + + +"pamAvailableLinkCapacity provides the number of free linkconnections in the plcmlink available for a client usage. This attribute is imported from "Rec. G.853.8", COMMUNITY: pre-provisioned adaptation management." + +#### RELATIONSHIP + + + + + +## 8.3 plcmlinkconnection + + + +#### DEFINITION + +"This object class is derived from ." + +#### ATTRIBUTE + + + +" + +This attribute is imported from Recommendation G.853.1 and it is used to hold a user friendly name of the plcmlinkconnection." + + + +"This attribute is used to indicate to which caller the plcmlinkconnection has been assigned. The initial value for this attribute is NULL." + +#### RELATIONSHIP + + + + + +## 8.4 **plcmLinkEnd** + + + +#### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + + + +"pamAvailableLinkCapacity provides the number of free networkCTPs in the plcmLinkEnd available for a client usage. This attribute is imported from "Rec. G.853.8", COMMUNITY: pre-provisioned adaptation management." + +#### RELATIONSHIP + + + + + +## 8.5 **plcmNetworkCTP** + + + +#### DEFINITION + +"This object class is derived from ." + +### ATTRIBUTE + + + +" + +This attribute is imported from Recommendation G.853.1 and it is used to hold a user friendly name of the plcmNetworkCTP." + + + +"This attribute is used to indicate to which caller the plcmNetworkCTP has been assigned. The initial value for this attribute is NULL." + +#### RELATIONSHIP + + + + + +## 9 **Information relationship definitions** + +None additional. + +## 10 **Static schemas** + +None. + +## 11 **Dynamic schemas** + +None. + +## 12 Attributes + +## 12.1 plcmCallerId + + + + + + + +#### DEFINITION + +"This attribute is used to indicate to which caller the transport entity has been assigned. When the transport entity is not assigned, the value has to be NULL. When the transport entity is assigned, the value has to be different from NULL." + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file 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sha256:80569a14d99f9af2d2c8282e2471f34f1e146dc8d6daac64fcc172d6284f9fa7 +size 25781 diff --git a/marked/G/T-REC-G.854.3-199903-I_PDF-E/raw.md b/marked/G/T-REC-G.854.3-199903-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..5393e32dcdbe9c93449e0bbcd04b95294ecbdd24 --- /dev/null +++ b/marked/G/T-REC-G.854.3-199903-I_PDF-E/raw.md @@ -0,0 +1,2177 @@ + + +![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with the letters ITU and a lightning bolt. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.854.3** + +(03/99) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital networks – +Management of transport network + +# --- **Computational viewpoint for topology management** + +ITU-T Recommendation G.854.3 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.849 | +| Management of transport network | G.850–G.859 | +| SDH radio and satellite systems integration | G.860–G.869 | +| Optical transport networks | G.870–G.879 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +# **COMPUTATIONAL VIEWPOINT FOR TOPOLOGY MANAGEMENT** + +## **Summary** + +The topology management community is used to managing the topology of a layer network domain and the relationships between the resources of the layer network domain being managed. The service provided by the community allows for the creation and deletion of the following resources inside a layer network domain: subnetwork, link, topological link, link end, topological link end and access group. The service also provides a set of reporting actions to advise potential notification receivers of creation and deletion of resources in the community. The service is available between one single caller and one single provider. + +The partitioning of subnetworks and links is not addressed in this community. + +Enterprise community actions covered by this specification: + +- create access group; +- delete access group; +- create link; +- delete link; +- create link end; +- delete link end; +- create subnetwork; +- delete subnetwork; +- create topological link; +- delete topological link; +- create topological link end; +- delete topological link end; +- report access group creation; +- report access group deletion; +- report link creation; +- report link deletion; +- report link end creation; +- report link end deletion; +- report subnetwork creation; +- report subnetwork deletion; +- report topological link creation; +- report topological link deletion; +- report topological link end creation; +- report topological link end deletion. + +### **Source** + +ITU-T Recommendation G.854.3 was prepared by ITU-T Study Group 4 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 26th of March 1999. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +### NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +###### Page + +| | | | +|-------|-------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References ..... | 1 | +| 3 | Definitions ..... | 1 | +| 4 | Abbreviations ..... | 1 | +| 5 | Conventions ..... | 2 | +| 6 | Label references ..... | 2 | +| 7 | Interfaces ..... | 3 | +| 7.1 | Query interfaces ..... | 3 | +| 7.2 | Operational interfaces ..... | 6 | +| 7.2.1 | Common resource interface ..... | 6 | +| 7.2.2 | Topology resources provisioning interface ..... | 7 | +| 7.3 | Report interfaces ..... | 20 | +| 7.3.1 | Common report resourceId change interface ..... | 20 | +| 7.3.2 | Topology resources reporting interface ..... | 21 | +| 7.4 | ASN.1 supporting productions ..... | 30 | + + + +# **COMPUTATIONAL VIEWPOINT FOR TOPOLOGY MANAGEMENT** + +*(Geneva, 1999)* + +# **1 Scope** + +This computational viewpoint specification is related to the topology management enterprise specification defined in Recommendation G.852.3 and the topology management information specification defined in Recommendation G.853.3. + +# **2 References** + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.851.1 (1996), *Management of the transport network – Application of the RM-ODP framework.* +- [2] ITU-T Recommendation G.853.1 (1999), *Common elements of the information viewpoint for the management of a transport network.* +- [3] ITU-T Recommendation G.852.3 (1999), *Enterprise viewpoint for topology management.* +- [4] ITU-T Recommendation G.853.3 (1999), *Information viewpoint for topology management.* + +# **3 Definitions** + +None. + +# **4 Abbreviations** + +This Recommendation uses the following abbreviations: + +| | | +|---------|---------------------------------------| +| AG | Access Group | +| ASN.1 | Abstract Syntax Notation One | +| CTP | Connection Termination Point | +| Id | Identifier | +| Ifce | Interface | +| inv | invariant | +| ITU | International Telecommunication Union | +| layerND | layer Network Domain | +| LE | Link End | +| LND | Layer Network Domain | + +| | | +|--------|-------------------------------------------------| +| NTTP | Network Trail Termination Point | +| RM-ODP | Reference Model for Open Distributed Processing | +| SN | Subnetwork | +| SNC | Subnetwork Connection | +| SNTP | Subnetwork Termination Point | +| TL | Topological Link | +| TLE | Topological Link End | +| topman | topology management | +| TP | Termination Point | +| TTP | Trail Termination Point | + +# 5 Conventions + +In order to increase the readability of the behaviour in the operations: + +- parameters are written in **bold**; +- elements defined in the information specification are written in *italic*. + +# 6 Label references + +| Full label reference | Local label reference | +|-------------------------------------------------------------------------------|--------------------------------| +| <"Rec. G.853.1", INFORMATION_OBJECT:linkConnection> | linkConnection | +| <"Rec. G.853.1", INFORMATION_OBJECT:networkCTP> | networkCTP | +| <"Rec. G.853.1", INFORMATION_OBJECT:subnetworkConnection> | subnetworkConnection | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanAccessGroup> | topmanAccessGroup | +| <"Rec. G.853.3", INFORMATION_OBJECT:
topmanLayerNetworkDomain> | topmanLayerNetworkDomain | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanLink> | topmanLink | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanLinkEnd> | topmanLinkEnd | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanNetworkTTP> | topmanNetworkTTP | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanSubnetwork> | topmanSubnetwork | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanSubnetworkTP> | topmanSubnetworkTP | +| <"Rec. G.853.3", INFORMATION_OBJECT: topmanTopologicalLink> | topmanTopologicalLink | +| <"Rec. G.853.3", INFORMATION_OBJECT:
topmanTopologicalLinkEnd> | topmanTopologicalLinkEnd | +| <"Rec. G.853.1", ATTRIBUTE: linkDirectionality> | linkDirectionality | +| <"Rec. G.853.1", ATTRIBUTE: pointDirectionality> | pointDirectionality | +| <"Rec. G.853.1", ATTRIBUTE: resourceId> | resourceId | +| <"Rec. G.853.1", ATTRIBUTE: signalIdentification> | signalIdentification | +| <"Rec. G.853.1", ATTRIBUTE: topologicalEndDirection> | topologicalEndDirection | +| <"Rec. G.853.1", ATTRIBUTE: userLabel> | userLabel | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP:
accessGroupIsMadeOfNetworkTTPs> | accessGroupIsMadeOfNetworkTTPs | + +| Full label reference | Local label reference | +|---------------------------------------------------------------------------------------------|--------------------------------------------------| +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: layerNetworkDomainIsMadeOf> | layerNetworkDomainIsMadeOf | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkBinds> | linkBinds | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkConnectionIsTerminatedByTopologicalEntities> | linkConnectionIsTerminatedByTopological Entities | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkEndHasNetworkCTPs> | linkEndHasNetworkCTPs | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkEndIsBoundTo> | linkEndIsBoundTo | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: linkHasLinkConnections> | linkHasLinkConnections | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: subnetworkHasSubnetworkConnections> | subnetworkHasSubnetwork Connections | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: subnetworkIsDelimitedBy> | subnetworkIsDelimitedBy | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: subnetworkTPIsRelatedToExtremity> | subnetworkTPIsRrelatedToExtremity | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: topologicalLinkEndIsSupportedByNetworkTTP> | topologicalLinkEndIsSupportedBy NetworkTTP | +| <"Rec. G.853.1", INFORMATION_RELATIONSHIP: topologicalLinkIsSupportedByTrail> | topologicalLinkIsSupportedByTrail | + +| Full ASN.1 production reference | Local label reference | +|------------------------------------------------------------|-----------------------| +| <"Rec. X.721:1992: Attribute-ASN1Module" : SimpleNameType> | SimpleNameType | +| <"Rec. X.680:1997" : GraphicString> | GraphicString | + +# 7 Interfaces + +This specification does not define operations which change the *userLabel* of the resources or report this change to the notification receiver because they do not change the state of the system. Their exact signature will be developed as part of the engineering viewpoint, with the concerned technology. + +## 7.1 Query interfaces + +This specification refers to interfaces that allow get access to identification and properties of resources involved in the "topology management" community. As the invocation of contained operations do not modify any state, there is no interest to develop them explicitly. Their exact signature will be developed as part of the engineering viewpoint, with the concerned technology. These interfaces are listed in the following table with the information they allow access to. + +| Interface name | Information object | Attributes and relationships | +|-----------------------------------|----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| topmanAccessGroupQueryIfce | |





| +| topmanLayerNetworkDomainQueryIfce | |

| +| topmanLinkEndQueryIfce | |





| +| topmanLinkQueryIfce | |





| +| topmanNetworkTTPQueryIfce | |



| + +| Interface name | Information object | Attributes and relationships | +|------------------------------------|----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| topmanSubnetwork QueryIfce | |







| +| topmanSubnetworkTP QueryIfce | |




| +| topmanTopological LinkEndQueryIfce | |





| +| topmanTopological LinkQueryIfce | |





| + +## 7.2 Operational interfaces + +### 7.2.1 Common resource interface + +The common resource interface provides functionality for changing the resource identifier of the resources by using the operation "change resource identifier". It satisfies the enterprise requirements stated in <"Rec. G.852.2", COMMUNITY: Transport Network Enterprise Model, General policy>. + +COMPUTATIONAL\_INTERFACE commonResourceIfce { + +OPERATION ; } + +#### 7.2.1.1 Change resource identifier + +<"Rec. G.852.2", COMMUNITY: Transport Network Enterprise Model, General policy> + +OPERATION changeResourceId { + +INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId ::= TopmanLayerNetworkDomainQueryIfce; +involvedResource: ResourceChoice +newResourceIdentifier: UserIdentifier ::= SimpleNameType; + +OUTPUT\_PARAMETERS + +agreedResourceIdentifier: UserIdentifier ::= SimpleNameType; + +RAISED\_EXCEPTIONS + +invalidResource: NULL; +newResourceIdentifierNotUnique: newResourceIdentifier; +failureToChangeId: NULL; + +BEHAVIOUR + +SEMI\_FORMAL + +PARAMETER\_MATCHING + +layerND: ; +involvedResource: ; +newResourceIdentifier: ; +agreedResourceIdentifier: ; + +PRE\_CONDITIONS + +inv\_existingInvolvedResource + +"**involvedResource** shall refer to *element* in the same relationship where **layerND** refers to *containerLND*." + +inv\_uniqueResourceId + +"**newResourceIdentifier** must not be equal to of any *element* in the same relationship where **layerND** refers to *containerLND*." + +POST\_CONDITIONS + +inv\_idChanged + +" of the resource referred to by **involvedResource** has to be equal to **newResourceIdentifier** and **agreedResourceIdentifier**." + +EXCEPTIONS + +IF PRE\_CONDITION inv\_existingInvolvedResource NOT\_VERIFIED RAISE\_EXCEPTION +invalidResource; +IF PRE\_CONDITION inv\_uniqueResourceId NOT\_VERIFIED RAISE\_EXCEPTION +newResourceIdentifierNotUnique; + +``` + + IF POST_CONDITION inv_idChanged NOT_VERIFIED RAISE_EXCEPTION failureToChangeId; +; } + +``` + +### 7.2.2 Topology resources provisioning interface + +The Topology Resources Provisioning Interface provides functionality for the provisioning of the resources defined in <"Rec. G.852.2", COMMUNITY: Transport Network Enterprise Model>. + +``` + +COMPUTATIONAL_INTERFACE topologyResourcesProvisioningIfce { + OPERATION + ; + ; + ; + ; + ; + ; + ; + ; + ; + ; + ; + ; } + +``` + +#### 7.2.2.1 Create access group + + + +``` + +OPERATION createAccessGroup { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + suppliedUserIdentifier: UserIdentifier; + -- zero length string or 0 implies none supplied. + suppliedUserLabel: GraphicString; + -- zero length string implies none supplied. + suppliedDirection: topologicalEndDirection; + + OUTPUT_PARAMETERS + accessGroup: AccessGroupId; + + RAISED_EXCEPTIONS + userIdentifierNotUnique: suppliedUserIdentifier; + failureToSetUserIdentifier: NULL; + failureToSetUserLabel: NULL; + failureToCreateAccessGroup: NULL; + failureToSetDirection: NULL; + +``` + +##### BEHAVIOUR + +##### SEMI\_FORMAL + +##### PARAMETER\_MATCHING + +``` + + layerND: ; + suppliedUserIdentifier: ; + suppliedUserLabel: ; + accessGroup: ; + suppliedDirection: ; + +``` + +##### PRE\_CONDITIONS + +inv\_uniqueUserIdentifier + +"The **suppliedUserIdentifier** value shall not be equal to the value of any element in the relationship where the **layerND** refers to *containerLND*." + +##### POST\_CONDITIONS + +inv\_agreedUserIdentifier + +"The ** value of ** referred to by **accessGroup** is equal to the **suppliedUserIdentifier** value, if it is supplied." + +inv\_agreedUserLabel + +"The ** value of ** referred to by **accessGroup** is equal to the **suppliedUserLabel** value, if it is supplied." + +inv\_existingAccessGroup + +"**accesssGroup** refers to *element* in the ** relationship where **layerND** refers to *containerLND*." + +inv\_agreedDirection + +"The ** value of ** referred to by **accessGroup** is equal to the **suppliedDirection** value, if it is supplied, or set to 'undefined' if not supplied." + +##### EXCEPTIONS + +IF PRE\_CONDITION inv\_uniqueUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION +userIdentifierNotUnique; + +IF POST\_CONDITION inv\_agreedUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetUserIdentifier; + +IF POST\_CONDITION inv\_agreedUserLabel NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetUserLabel; + +IF POST\_CONDITION inv\_existingAccessGroup NOT\_VERIFIED RAISE\_EXCEPTION +failureToCreateAccessGroup; + +IF POST\_CONDITION inv\_agreedDirection NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetDirection; + +;} + +#### 7.2.2.2 Delete access group + + + +OPERATION deleteAccessGroup { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +accessGroup: AccessGroupId; + +##### OUTPUT\_PARAMETERS + +-- none + +##### RAISED\_EXCEPTIONS + +incorrectAccessGroup: accessGroup; +networkTTPsExisting: NULL; +failureToDeleteAccessGroup: NULL; + +##### BEHAVIOUR + +##### SEMI\_FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +accessGroup: ; + +##### PRE\_CONDITIONS + +inv\_existingAccessGroup + +"**accesssGroup** refers to *element* in the ** relationship where **layerND** refers to *containerLND*." + +inv\_noNetworkTTPs + +"**accessGroup** shall not refer to any *containerAG* in a ** relationship." + +``` + +POST_CONDITIONS +inv_noAccessGroup + "accessGroup does not refer to any element in the relationship." + +EXCEPTIONS + IF PRE_CONDITION inv_existingAccessGroup NOT_VERIFIED RAISE_EXCEPTION + incorrectAccessGroup; + IF PRE_CONDITION inv_noNetworkTTPs NOT_VERIFIED RAISE_EXCEPTION networkTTPsExisting; + IF POST_CONDITION inv_noAccessGroup NOT_VERIFIED RAISE_EXCEPTION + failureToDeleteAccessGroup; +;} + +``` + +#### 7.2.2.3 Create link + + + +``` + +OPERATION createLink { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + a_End: LinkEndChoice; + z_End: LinkEndChoice; + suppliedUserIdentifier: UserIdentifier; + -- zero length string or 0 implies none supplied. + suppliedUserLabel: GraphicString; + -- zero length string implies none supplied. + suppliedDirectionality: linkDirectionality; + + OUTPUT_PARAMETERS + link: LinkId; + + RAISED_EXCEPTIONS + incorrectLinkEnds: LinkEndChoice; + userIdentifierNotUnique: suppliedUserIdentifier; + failureToSetUserIdentifier: NULL; + failureToCreateLink: NULL; + failureToBindLink: NULL; + failureToSetUserLabel: NULL; + failureToSetDirectionality: NULL; + + BEHAVIOUR + SEMI_FORMAL + PARAMETER_MATCHING + layerND: ; + subnetwork: ; + accessGroup: ; + suppliedUserIdentifier: ; + suppliedUserLabel: ; + suppliedDirectionality: ; + link: ; + + PRE_CONDITIONS + inv_sameLayerND + "a_End and z_End shall both refer to element in the same relationship + where layerND refers to containerLND." + + inv_uniqueUserIdentifier + "The suppliedUserIdentifier value shall not be equal to the value of any element in the + relationship where layerND refers to containerLND." + +``` + +``` + + POST_CONDITIONS + inv_existingLink + "link, a_End and z_End refer to element in the relationship where + layerND refers to containerLND." + + inv_linkBinds + "a_End and z_End respectively refer to a_endTopological and z_endTopological in the + relationship where link refers to transferCapacityLink." + + inv_agreedUserIdentifier + "The value of referred to by link is equal to the suppliedUserIdentifier value, + if it is supplied." + + inv_agreedUserLabel + "The value of referred to by link is equal to the suppliedUserLabel value, if it is + supplied." + + "inv_agreedDirectionality + "The value of referred to by link is equal to the + suppliedDirectionality value, if it is supplied, or set to 'undefined' if not supplied." + + EXCEPTIONS + IF PRE_CONDITION inv_sameLayerND NOT_VERIFIED RAISE_EXCEPTION incorrectLinkEnds; + IF PRE_CONDITION inv_uniqueUserIdentifier NOT_VERIFIED RAISE_EXCEPTION + userIdentifierNotUnique; + IF POST_CONDITION inv_existingLink NOT_VERIFIED RAISE_EXCEPTION failureToCreateLink; + IF POST_CONDITION inv_linkBinds NOT_VERIFIED RAISE_EXCEPTION failureToBindLink; + IF POST_CONDITION inv_agreedUserIdentifier NOT_VERIFIED RAISE_EXCEPTION + failureToSetUserIdentifier; + IF POST_CONDITION inv_agreedUserLabel NOT_VERIFIED RAISE_EXCEPTION failureToSetUserLabel; + IF POST_CONDITION inv_agreedDirectionality NOT_VERIFIED RAISE_EXCEPTION + failureToSetDirectionality; + ;} + +``` + +#### 7.2.2.4 Delete link + + + +``` + +OPERATION deleteLink { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + link: LinkId; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + incorrectLink: link; + linkConnectionExisting: NULL; + failureToDeleteLink: NULL; + + BEHAVIOUR + SEMI_FORMAL + PARAMETER_MATCHING + layerND: ; + link: ; + +``` + +``` + + PRE_CONDITIONS; + inv_existingLink + "link refers to the element in the relationship where layerND refers to containerLND." + + inv_noLinkConnection + "link shall not refer to any containerLink of a relationship." + + POST_CONDITIONS + inv_noLink + "link does not participate in any AND relationships." + + EXCEPTIONS + IF PRE_CONDITION inv_existingLink NOT_VERIFIED RAISE_EXCEPTION incorrectLink; + IF PRE_CONDITION inv_noLinkConnection NOT_VERIFIED RAISE_EXCEPTION + linkConnectionExisting; + IF POST_CONDITION inv_noLink NOT_VERIFIED RAISE_EXCEPTION failureToDeleteLink; +;} + +``` + +#### 7.2.2.5 Create link end + +This operation creates a link end bound to a subnetwork. + + + +``` + +OPERATION createLinkEnd { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + subnetwork: SubnetworkId; + suppliedUserIdentifier: UserIdentifier; + -- zero length string or 0 implies none supplied. + suppliedUserLabel: GraphicString; + -- zero length string implies none supplied. + suppliedDirection: topologicalEndDirection; + + OUTPUT_PARAMETERS + linkEnd: LinkEndId; + + RAISED_EXCEPTIONS + incorrectSubnetwork: subnetwork; + userIdentifierNotUnique: suppliedUserIdentifier; + failureToCreateLinkEnd: NULL; + failureToBindLinkEnd: NULL; + failureToSetUserIdentifier: NULL; + failureToSetUserLabel: NULL; + failureToSetDirection: NULL; + + BEHAVIOUR + SEMI_FORMAL + + PARAMETER_MATCHING + layerND: ; + subnetwork: ; + suppliedUserIdentifier: ; + suppliedUserLabel: ; + suppliedDirection: ; + linkEnd: ; + +``` + +##### PRE\_CONDITIONS + +inv\_subnetworkExisting + +"**subnetwork** shall refer to *element* in the ** relationship where **layerND** refers to *containerLND*." + +inv\_uniqueUserIdentifier + +"The **suppliedUserIdentifier** value shall not be equal to the ** value of any *element* in the ** relationship where **layerND** refers to *containerLND*." + +##### POST\_CONDITIONS + +inv\_existingLinkEnd + +"**linkEnd** and **subnetwork** refer to *element* in the same ** relationship where **layerND** refers to *containerLND*." + +inv\_boundLinkEnd + +"**linkEnd** refers to *transferCapacityLE* in the ** relationship where **subnetwork** refers to *topologicalEntity*." + +inv\_agreedUserIdentifier + +"The ** value of ** referred to by **linkEnd** is equal to the **suppliedUserIdentifier** value, if it is supplied." + +inv\_agreedUserLabel + +"The ** value of ** referred to by **linkEnd** is equal to the **suppliedUserLabel** value, if it is supplied." + +inv\_agreedDirection + +"The ** value of ** referred to by **linkEnd** is equal to the **suppliedDirection** value, if it is supplied, or set to 'undefined' if not supplied." + +##### EXCEPTIONS + +IF PRE\_CONDITION inv\_subnetworkExisting NOT\_VERIFIED RAISE\_EXCEPTION +incorrectSubnetwork; + +IF PRE\_CONDITION inv\_uniqueUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION +userIdentifierNotUnique; + +IF POST\_CONDITION inv\_existingLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION +failureToCreateLinkEnd; + +IF POST\_CONDITION inv\_boundLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION failureToBindLinkEnd; + +IF POST\_CONDITION inv\_agreedUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetUserIdentifier; + +IF POST\_CONDITION inv\_agreedUserLabel NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetUserLabel; + +IF POST\_CONDITION inv\_agreedDirection NOT\_VERIFIED RAISE\_EXCEPTION failureToSetDirection; + +;} + +#### 7.2.2.6 Delete link end + + + +OPERATION deleteLinkEnd { + +INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; + +linkEnd: LinkEndId; + +OUTPUT\_PARAMETERS + +-- none + +RAISED\_EXCEPTIONS + +incorrectLinkEnd: linkEnd; + +networkCTPExisting: NULL; + +failureToDeleteLinkEnd: NULL; + +##### BEHAVIOUR + +##### SEMI\_FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +linkEnd: ; + +##### PRE\_CONDITIONS + +inv\_existingLinkEnd + +"**linkEnd** refers to *element* in the <*layerNetworkDomainIsMadeOf*> relationship where **layerND** refers to *containerLND*." + +inv\_noNetworkCTPs + +"**linkEnd** shall not refer to any *containerLE* in a <*linkEndHasNetworkCTPs*> relationship." + +##### POST\_CONDITIONS + +inv\_noLinkEnd + +"**linkEnd** does not refer to any *element* in the <*layerNetworkDomainIsMadeOf*> relationship." + +##### EXCEPTIONS + +IF PRE\_CONDITION inv\_existingLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION incorrectLinkEnd; +IF PRE\_CONDITION inv\_noNetworkCTPs NOT\_VERIFIED RAISE\_EXCEPTION networkCTPExisting; +IF POST\_CONDITION inv\_noLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION failureToDeleteLinkEnd; + +;} + +#### 7.2.2.7 Create subnetwork + + + +OPERATION createSubnetwork { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +suppliedUserIdentifier: UserIdentifier; +-- *zero length string or 0 implies none supplied.* +suppliedUserLabel: GraphicString; +-- *zero length string implies none supplied.* + +##### OUTPUT\_PARAMETERS + +subnetwork: SubnetworkId; +networkTTPs: SetOfNetworkTTPs; +-- *the networkTTPs parameter value is provided when is supported.* + +##### RAISED\_EXCEPTIONS + +userIdentifierNotUnique: suppliedUserIdentifier; +failureToSetUserIdentifier: NULL; +failureToSetUserLabel: NULL; +failureToCreateSubnetwork: NULL; +failureToCreateNTTP: NULL; +failureToAssociateNTTP: NULL; + +##### BEHAVIOUR + +##### SEMI\_FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +suppliedUserIdentifier: ; +suppliedUserLabel: ; +subnetwork: ; +networkTTPs ELEMENTS: ; + +##### PRE\_CONDITIONS + +inv\_uniqueUserIdentifier + +"The **suppliedUserIdentifier** value shall not be equal to the ** value of any *element* in the ** relationship where **layerND** refers to *containerLND*." + +##### POST\_CONDITIONS + +inv\_agreedUserIdentifier + +"The ** value of the ** referred to by **subnetwork** is equal to the **suppliedUserIdentifier** value, if it is supplied." + +inv\_agreedUserLabel + +"The ** value of the ** referred to by **subnetwork** is equal to the **suppliedUserIdentifier** value, if it is supplied." + +inv\_existingSubnetwork + +"**subnetwork** refers to *element* in the ** relationship where **layerND** refers to *containerLND*." + +-- NOTE – The following invariants are only needed if the networkTTPs appear automatically when the subnetwork is created. + +inv\_existingNetworkTTP + +"**networkTTPs** refers to *element* in the ** relationship where **layerND** refers to *containerLND*." + +inv\_nttpAssociated + +"**networkTTPs** refers to *extremity* of the ** relationship where the *abstractionSNTP* (which is a subnetworkTP) is also *elementSNTP* of a ** relationship where **subnetwork** refers to *containerSN*." + +![UML Class Diagram showing relationships between subnetwork, subnetworkTP, and networkTTP classes.](37819f1170c36655c57129b6bd8a5ceb_img.jpg) + +``` + +classDiagram + subnetwork "1..1" -- "1..N" subnetworkTP : subnetworkIsDelimitedBy + subnetworkTP "1..N" -- "1..1" networkTTP : subnetworkTPsIsRelatedToExtremity + + subnetwork : containerSN (1..1) + subnetworkTP : elementSNTP (1..N) + subnetworkTP : abstractionSNTP (1..N) + networkTTP : extremity (1..1) + +``` + +The diagram shows three stacked boxes representing classes. + Top box: **subnetwork**. + Middle box: **subnetworkTP**. + Bottom box: **networkTTP**. + A vertical line connects **subnetwork** to **subnetworkTP**. Near **subnetwork**, it is labeled *containerSN* (1..1). Near **subnetworkTP**, it is labeled *elementSNTP* (1..N). The relationship is named *subnetworkIsDelimitedBy*. + A vertical line connects **subnetworkTP** to **networkTTP**. Near **subnetworkTP**, it is labeled *abstractionSNTP* (1..N). Near **networkTTP**, it is labeled *extremity* (1..1). The relationship is named *subnetworkTPsIsRelatedToExtremity*. + +UML Class Diagram showing relationships between subnetwork, subnetworkTP, and networkTTP classes. + +"; + +##### EXCEPTIONS + +IF PRE\_CONDITION inv\_uniqueUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION + +userIdentifierNotUnique; + +IF POST\_CONDITION inv\_agreedUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION + +failureToSetUserIdentifier; + +IF POST\_CONDITION inv\_agreedUserLabel NOT\_VERIFIED RAISE\_EXCEPTION failureToSetUserLabel; + +IF POST\_CONDITION inv\_existingSubnetwork NOT\_VERIFIED RAISE\_EXCEPTION + +failureToCreateSubnetwork; + +IF POST\_CONDITION inv\_existingNetworkTTP NOT\_VERIFIED RAISE\_EXCEPTION + +failureToCreateNTTP; + +``` +IF POST_CONDITION inv_nttpAssociated NOT_VERIFIED RAISE_EXCEPTION failureToAssociateNTTP; +;} +``` + +#### 7.2.2.8 Delete subnetwork + + + +OPERATION deleteSubnetwork { + +INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; + +subnetwork: SubnetworkId; + +OUTPUT\_PARAMETERS + +-- none + +RAISED\_EXCEPTIONS + +incorrectSubnetwork: subnetwork; + +subnetworkInUse: NULL; + +subnetworkContainsSubnetworkConnections: NULL; + +boundSubnetwork: NULL; + +failureToDeleteSubnetwork: NULL; + +BEHAVIOUR + +SEMI\_FORMAL + +PARAMETER\_MATCHING + +layerND: ; + +subnetwork: ; + +PRE\_CONDITIONS + +inv\_existingSubnetwork + +"**subnetwork** refers to *element* in the relationship where **layerND** refers to *containerLND*." + +inv\_noSubnetworkTP + +"**subnetwork** shall not refer to any *containerSN* in a relationship." + +inv\_noSubnetworkConnections + +"**subnetwork** shall not refer to any *containerSN* in a relationship." + +inv\_noBinding + +"**subnetwork** shall not refer to any *a\_endTopological* or *z\_endTopological* in a or relationship or to any *topologicalEntity* in a relationship." + +POST\_CONDITIONS + +inv\_noSubnetwork + +"**subnetwork** must not refer to any *element* in a relationship." + +EXCEPTIONS + +IF PRE\_CONDITION inv\_existingSubnetwork NOT\_VERIFIED RAISE\_EXCEPTION + +incorrectSubnetwork; + +IF PRE\_CONDITION inv\_noSubnetworkTP NOT\_VERIFIED RAISE\_EXCEPTION subnetworkInUse; + +IF PRE\_CONDITION inv\_noSubnetworkConnection NOT\_VERIFIED RAISE\_EXCEPTION + +subnetworkContainsSubnetworkConnections; + +IF PRE\_CONDITION inv\_noBinding NOT\_VERIFIED RAISE\_EXCEPTION boundSubnetwork; + +IF POST\_CONDITION inv\_noSubnetwork NOT\_VERIFIED RAISE\_EXCEPTION + +failureToDeleteSubnetwork; + +;} + +#### 7.2.2.9 Create topological link + + + +OPERATION createTopologicalLink { + +INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +a\_End: LinkEndChoice; +z\_End: LinkEndChoice; +suppliedUserIdentifier: UserIdentifier; +-- zero length string or 0 implies none supplied. +suppliedUserLabel: GraphicString; +-- zero length string implies none supplied. +suppliedDirectionality: linkDirectionality; + +OUTPUT\_PARAMETERS + +topologicalLink: TopologicalLinkId; + +RAISED\_EXCEPTIONS + +incorrectLinkEnds: LinkEndChoice; +userIdentifierNotUnique: suppliedUserIdentifier; +failureToSetUserIdentifier: NULL; +failureToCreateTopologicalLink: NULL; +failureToBindTopologicalLink: NULL; +failureToSetUserLabel: NULL; +failureToSetDirectionality: NULL; + +BEHAVIOUR + +SEMI\_FORMAL + +PARAMETER\_MATCHING + +layerND: ; +subnetwork: ; +accessGroup: ; +suppliedUserIdentifier: ; +suppliedUserLabel: ; +suppliedDirectionality: ; +topologicalLink: ; + +PRE\_CONDITIONS + +inv\_sameLayerND + +"**a\_End** and **z\_End** shall both refer to *element* in the same relationship where **layerND** refers to *containerLND*." + +inv\_uniqueUserIdentifier + +"The **suppliedUserIdentifier** value shall not be equal to the value of any *element* in the relationship where **layerND** refers to *containerLND*." + +POST\_CONDITIONS + +inv\_existingTopologicalLink + +"**link**, **a\_End** and **z\_End** refer to *element* in the relationship where **layerND** refers to *containerLND*." + +inv\_linkBinds + +"**a\_End** and **z\_End** respectively refer to *a\_endTopological* and *z\_endTopological* in the relationship where **topologicalLink** refers to *transferCapacityLink*." + +inv\_agreedUserIdentifier + +"The value of referred to by **topologicalLink** is equal to the **suppliedUserIdentifier** value, if it is supplied." + +``` + +inv_agreedUserLabel + "The value of referred to by topologicalLink is equal to the + suppliedUserLabel value, if it is supplied." + +"inv_agreedDirectionality + "The value of referred to by topologicalLink is equal to the + suppliedDirectionality value, if it is supplied, or set to 'undefined' if not supplied." + +EXCEPTIONS + IF PRE_CONDITION inv_sameLayerND NOT_VERIFIED RAISE_EXCEPTION incorrectLinkEnds; + IF PRE_CONDITION inv_uniqueUserIdentifier NOT_VERIFIED RAISE_EXCEPTION + userIdentifierNotUnique; + IF POST_CONDITION inv_existingTopologicalLink NOT_VERIFIED RAISE_EXCEPTION + failureToCreateTopologicalLink; + IF POST_CONDITION inv_linkBinds NOT_VERIFIED RAISE_EXCEPTION failureToBindTopologicalLink; + IF POST_CONDITION inv_agreedUserIdentifier NOT_VERIFIED RAISE_EXCEPTION + failureToSetUserIdentifier; + IF POST_CONDITION inv_agreedUserLabel NOT_VERIFIED RAISE_EXCEPTION failureToSetUserLabel; + IF POST_CONDITION inv_agreedDirectionality NOT_VERIFIED RAISE_EXCEPTION + failureToSetDirectionality; +;} + +``` + +#### 7.2.2.10 Delete topological link + + + +``` + +OPERATION deleteTopologicalLink { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + topologicalLink: TopologicalLinkId; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + incorrectTopologicalLink: topologicalLink; + serverTrailExisting: NULL; + failureToDeleteTopologicalLink: NULL; + + BEHAVIOUR + SEMI_FORMAL + PARAMETER_MATCHING + layerND: ; + topologicalLink: ; + + PRE_CONDITIONS; + inv_existingTopologicalLink + "topologicalLink refers to the element in the relationship where + layerND refers to containerLND." + + inv_noServerTrail + "topologicalLink shall not refer to any clientTL of a relationship." + + POST_CONDITIONS + inv_noTopologicalLink + "topologicalLink does not participate in any AND + relationships." + +``` + +##### EXCEPTIONS + +``` +IF PRE_CONDITION inv_existingTopologicalLink NOT_VERIFIED RAISE_EXCEPTION + incorrectTopologicalLink; +IF PRE_CONDITION inv_noServerTrail NOT_VERIFIED RAISE_EXCEPTION serverTrailExisting; +IF POST_CONDITION inv_noTopologicalLink NOT_VERIFIED RAISE_EXCEPTION + failureToDeleteTopologicalLink; +``` + +;} + +#### 7.2.2.11 Create topological link end + +This operation creates a topological link end bound to a subnetwork. + + + +OPERATION createTopologicalLinkEnd { + +##### INPUT\_PARAMETERS + +``` +layerND: LayerNetworkDomainId; +subnetwork: SubnetworkId; +suppliedUserIdentifier: UserIdentifier; + -- zero length string or 0 implies none supplied. +suppliedUserLabel: GraphicString; + -- zero length string implies none supplied. +suppliedDirection: topologicalEndDirection; +``` + +##### OUTPUT\_PARAMETERS + +``` +topologicalLinkEnd: TopologicalLinkEndId; +``` + +##### RAISED\_EXCEPTIONS + +``` +incorrectSubnetwork: subnetwork; +userIdentifierNotUnique: suppliedUserIdentifier; +failureToCreateTopologicalLinkEnd: NULL; +failureToBindTopologicalLinkEnd: NULL; +failureToSetUserIdentifier: NULL; +failureToSetUserLabel: NULL; +failureToSetDirection: NULL; +``` + +##### BEHAVIOUR + +##### SEMI\_FORMAL + +##### PARAMETER\_MATCHING + +``` +layerND: ; +subnetwork: ; +suppliedUserIdentifier: ; +suppliedUserLabel: ; +suppliedDirection: ; +topologicalLinkEnd: ; +``` + +##### PRE\_CONDITIONS + +``` +inv_subnetworkExisting +``` + +"**subnetwork** shall refer to *element* in the relationship where **layerND** refers to *containerLND*." + +``` +inv_uniqueUserIdentifier +``` + +"The **suppliedUserIdentifier** value shall not be equal to the value of any *element* in the relationship where **layerND** refers to *containerLND*." + +##### POST\_CONDITIONS + +``` +inv_existingTopologicalLinkEnd +``` + +"**topologicalLinkEnd** and **subnetwork** refer to *element* in the same relationship where **layerND** refers to *containerLND*." + +inv\_boundTopologicalLinkEnd +"topologicalLinkEnd refers to *transferCapacityLE* in the relationship where +subnetwork refers to *topologicalEntity*." + +inv\_agreedUserIdentifier +"The value of referred to by topologicalLinkEnd is equal to +the suppliedUserIdentifier value, if it is supplied." + +inv\_agreedUserLabel +"The value of referred to by topologicalLinkEnd is equal to +the suppliedUserLabel value, if it is supplied." + +inv\_agreedDirection +"The value of referred to by +topologicalLinkEnd is equal to the suppliedDirection value, if it is supplied, or set to 'undefined' if not +supplied." + +##### EXCEPTIONS + +IF PRE\_CONDITION inv\_subnetworkExisting NOT\_VERIFIED RAISE\_EXCEPTION +incorrectSubnetwork; +IF PRE\_CONDITION inv\_uniqueUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION +userIdentifierNotUnique; +IF POST\_CONDITION inv\_existingTopologicalLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION +failureToCreateTopologicalLinkEnd; +IF POST\_CONDITION inv\_boundTopologicalLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION +failureToBindTopologicalLinkEnd; +IF POST\_CONDITION inv\_agreedUserIdentifier NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetUserIdentifier; +IF POST\_CONDITION inv\_agreedUserLabel NOT\_VERIFIED RAISE\_EXCEPTION failureToSetUserLabel; +IF POST\_CONDITION inv\_agreedDirection NOT\_VERIFIED RAISE\_EXCEPTION +failureToSetDirection; + +;} + +#### 7.2.2.12 Delete topological link end + + + +OPERATION deleteTopologicalLinkEnd { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +topologicalLinkEnd: TopologicalLinkEndId; + +##### OUTPUT\_PARAMETERS + +-- none + +##### RAISED\_EXCEPTIONS + +incorrectTopologicalLinkEnd: topologicalLinkEnd; +serverTTPEXisting: NULL; +failureToDeleteTopologicalLinkEnd: NULL; + +##### BEHAVIOUR + +##### SEMI\_FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +topologicalLinkEnd: ; + +##### PRE\_CONDITIONS + +inv\_existingTopologicalLinkEnd +"topologicalLinkEnd refers to *element* in the relationship where +layerND refers to *containerLND*." + +inv\_noServerTTP + +"**topologicalLinkEnd** shall not refer to any *clientTLE* in a + relationship." + +##### **POST\_CONDITIONS** + +inv\_noTopologicalLinkEnd + +"**topologicalLinkEnd** does not refer to any *element* in the relationship." + +##### **EXCEPTIONS** + +IF PRE\_CONDITION inv\_existingTopologicalLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION +incorrectTopologicalLinkEnd; + +IF PRE\_CONDITION inv\_noServerTTP NOT\_VERIFIED RAISE\_EXCEPTION serverTTPExisting; + +IF POST\_CONDITION inv\_noTopologicalLinkEnd NOT\_VERIFIED RAISE\_EXCEPTION +failureToDeleteTopologicalLinkEnd; + +;} + +## 7.3 Report interfaces + +### 7.3.1 Common report resourceId change interface + +The common report resourceId change interface provides functionality for reporting the change of the resource identifier of the resources by using the operation "report resourceId change". It satisfies the enterprise requirements stated in <"Rec. G.852.2", COMMUNITY: Transport Network Enterprise Model, General policy>. + +COMPUTATIONAL\_INTERFACE commonReportResourceIdChangeIfce { +OPERATION ; } + +#### 7.3.1.1 Report resourceId change + +<"Rec. G.852.2", COMMUNITY: Transport Network Enterprise Model, General policy> + +OPERATION reportResourceIdChange { + +##### **INPUT\_PARAMETERS** + +layerND: LayerNetworkDomainId; + +involvedResource: ResourceChoice + +oldResourceIdIdentifier: UserIdentifier ::= SimpleNameType; + +newResourceIdIdentifier: UserIdentifier ::= SimpleNameType; + +##### **OUTPUT\_PARAMETERS** + +-- none + +##### **RAISED\_EXCEPTIONS** + +-- none + +##### **BEHAVIOUR** + +##### **SEMI-FORMAL** + +##### **PARAMETER\_MATCHING** + +layerND: ; + +involvedResource: ; + +oldResourceIdIdentifier: ; + +newResourceIdIdentifier: ; + +##### **TRIGGERING\_CONDITIONS** + +##### **PRE\_CONDITIONS** + +inv\_existingInvolvedResource + +"**involvedResource** shall refer to *element* in the same relationship +where **layerND** refers to *containerLND*." + +``` + + inv_oldResourceIdentifier + " of the resource referred to by involvedResource must be equal to oldResourceIdentifier."; + + inv_differentNewResourceIdentifier + " of the resource referred to by involvedResource must be different from + newResourceIdentifier."; + + POST_CONDITIONS + inv_newResourceIdentifier + " of the resource referred to by involvedResource must be equal to newResourceIdentifier."; + + EXCEPTIONS + -- none +;} + +``` + +### 7.3.2 Topology resources reporting interface + +The Topology Resources Reporting Interface provides functionality for the reporting of the creation and deletion of the resources defined in <"Rec. G.852.2", COMMUNITY: Transport Network Enterprise Model>. + +``` + +COMPUTATIONAL_INTERFACE topologyResourcesReportingIfce { + OPERATION ; + ; + ; + ; + ; + ; + ; + ; + ; + ; } + ; + ; + ; + ; } + +``` + +#### 7.3.2.1 Report access group creation + + + +``` + +OPERATION reportAccessGroupCreation { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + accessGroup: AccessGroupId; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + -- none + + BEHAVIOUR + SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + accessGroup: ; + +``` + +``` + +TRIGGERING_CONDITIONS +PRE_CONDITIONS + -- none + +POST_CONDITIONS +inv_existingAccessGroup + "accessGroup refers to element in the relationship where layerND refers + to containerLND." + +EXCEPTIONS + -- none +;} + +``` + +#### 7.3.2.2 Report access group deletion + + + +``` + +OPERATION reportAccessGroupDeletion { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + accessGroup: AccessGroupId; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + -- none + + BEHAVIOUR + SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + accessGroup: ; + + TRIGGERING_CONDITIONS + PRE_CONDITIONS + inv_existingAccessGroup + "accessGroup refers to element in the relationship where layerND refers + to containerLND." + + inv_noNetworkTTPs + "accessGroup shall not refer to any containerAG in an + relationship." + + POST_CONDITIONS + inv_noAccessGroup + "accessGroup shall not refer to any element in the relationship." + + EXCEPTIONS + -- none +;} + +``` + +#### 7.3.2.3 Report link creation + + + +``` + +OPERATION reportLinkCreation { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + link: LinkId; + +``` + +a\_End: LinkEndChoice; +z\_End: LinkEndChoice; + +##### OUTPUT PARAMETERS + +-- none + +##### RAISED EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; link: ; +subnetwork: ; +accessGroup: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +-- none + +##### POST\_CONDITIONS + +##### inv\_existingLink + +"**link** refers to *element* in the relationship where **layerND** refers to *containerLND*." + +##### inv\_linkBinds + +"**a\_End** and **z\_End** respectively refer to *a\_endTopological* and *z\_endTopological* in the relationship where **link** refers to *transferCapacityLink*." + +##### EXCEPTIONS + +-- none + +;} + +#### 7.3.2.4 Report link deletion + + + +##### OPERATION reportLinkDeletion { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +link: LinkId; + +##### OUTPUT\_PARAMETERS + +-- none + +##### RAISED\_EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +link: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +##### inv\_existingLink + +"**link** refers to *element* in the relationship where **layerND** refers to *containerLND*." + +``` + +inv_noLinkConnection + "link shall not refer to any containerLink of a relationship." + +POST_CONDITIONS +inv_noLink + "link does not refer to any element in the relationship." + +EXCEPTIONS + -- none +;} + +``` + +#### 7.3.2.5 Report link end creation + + + +``` + +OPERATION reportLinkEndCreation { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + linkEnd: LinkEndId; + subnetwork: SubnetworkId; + + OUTPUT PARAMETERS + -- none + + RAISED EXCEPTIONS + -- none + +BEHAVIOUR +SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + linkEnd: ; + subnetwork: ; + + TRIGGERING_CONDITIONS + PRE_CONDITIONS + -- none + + POST_CONDITIONS + inv_existingLinkEnd + "linkEnd and subnetwork refer to element in the same relationship + where layerND refers to containerLND." + + inv_boundLinkEnd + "linkEnd refers to transferCapacityLE in the relationship where subnetwork refers to + topologicalEntity." + +EXCEPTIONS + -- none +;} + +``` + +#### 7.3.2.6 Report link end deletion + + + +``` + +OPERATION reportLinkEndDeletion { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + linkEnd: LinkEndId; + +``` + +##### OUTPUT PARAMETERS + +-- none + +##### RAISED EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +linkEnd: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +inv\_existingLinkEnd + +"**linkEnd** refers to *element* in the relationship where **layerND** refers to *containerLND*." + +inv\_existingLinkEndBinding + +"**linkEnd** refers to *topologicalEntity* in the relationship." + +inv\_noNetworkCTPs + +"**linkEnd** shall not refer to any *containerLE* in a relationship." + +##### POST\_CONDITIONS + +inv\_noLinkEnd + +"**linkEnd** does not refer to any *element* in the relationship where **layerND** refers to *containerLND*." + +##### EXCEPTIONS + +-- none + +;} + +#### 7.3.2.7 Report subnetwork creation + + + +OPERATION reportSubnetworkCreation { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +subnetwork: SubnetworkId; +networkTTPs: SetOfNnetworkTTPs; +-- the networkTTPs parameter value is provided when is supported. + +##### OUTPUT\_PARAMETERS + +-- none + +##### RAISED\_EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +subnetwork: ; +networkTTPs ELEMENTS: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +-- none + +``` + + POST_CONDITIONS + inv_existingSubnetwork + "subnetwork refer to the element in the relationship where layerND + refers to containerLND." + ; + + EXCEPTIONS + -- none +; +} + +``` + +#### 7.3.2.8 Report subnetwork deletion + + + +``` + +OPERATION reportSubnetworkDeletion { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + subnetwork: SubnetworkId; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + -- none + + BEHAVIOUR + SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + subnetwork: ; + + TRIGGERING_CONDITIONS + PRE_CONDITIONS + inv_existingSubnetwork + "subnetwork must refer to element in a relationship where layerND + refers to containerLND." + + inv_noSubnetworkTP + "subnetwork shall not refer to any containerSN in a relationship." + + inv_noBinding + "subnetwork shall not refer to any a_endTopological or z_endTopological in a relationship or + to any topologicalEntity in a relationship." + + POST_CONDITIONS + inv_noSubnetwork + "subnetwork does not participate in the relationship." + + EXCEPTIONS + -- none +; +} + +``` + +#### 7.3.2.9 Report subnetworkTP creation + + + +``` + +OPERATION reportSubnetworkTPCreation { + INPUT PARAMETERS + layerND: LayerNetworkDomainId; + subnetworkTP: SubnetworkTPId ::= SimpleNameType; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + -- none + + BEHAVIOUR + SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + subnetworkTP: ; + + TRIGGER CONDITION + PRE_CONDITIONS + -- none + + POST_CONDITIONS + inv_existingSubnetworkTP + "subnetworkTP refer to the element in the relationship where layerND + refers to containerLND." + ; + + EXCEPTIONS + -- none +}; + +``` + +#### 7.3.2.10 Report subnetworkTP deletion + + + +``` + +OPERATION reportSubnetworkTPDeletion { + INPUT PARAMETERS + layerND: LayerNetworkDomainId; + subnetworkTP: SubnetworkTPId ::= SimpleNameType; + + OUTPUT_PARAMETERS + -- none + + RAISED_EXCEPTIONS + -- none + + BEHAVIOUR + SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + subnetworkTP: ; + + TRIGGER CONDITION + PRE_CONDITIONS + inv_existingSubnetworkTP + "subnetworkTP must refer to element in a relationship where layerND + refers to containerLND." + ; + +``` + +``` + +POST_CONDITIONS + inv_noSubnetworkTP + "subnetworkTP does not participate in the relationship." + +EXCEPTIONS + -- none +;} + +``` + +#### 7.3.2.11 Report topological link creation + + + +``` + +OPERATION reportTopologicalLinkCreation { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + topologicalLink: TopologicalLinkId; + a_End: LinkEndChoice; + z_End: LinkEndChoice; + + OUTPUT PARAMETERS + -- none + + RAISED EXCEPTIONS + -- none + + BEHAVIOUR + SEMI-FORMAL + PARAMETER_MATCHING + layerND: ; + topologicalLink: ; + subnetwork: ; + accessGroup: ; + + TRIGGERING_CONDITIONS + PRE_CONDITIONS + -- none + + POST_CONDITIONS + inv_existingTopologicalLink + "topologicalLink refers to element in the relationship where layerND + refers to containerLND." + + inv_linkBinds + "a_End and z_End respectively refer to a_endTopological and z_endTopological in the + relationship where link refers to transferCapacityLink." + + EXCEPTIONS + -- none +;} + +``` + +#### 7.3.2.12 Report topological link deletion + + + +``` + +OPERATION reportTopologicalLinkDeletion { + INPUT_PARAMETERS + layerND: LayerNetworkDomainId; + topologicalLink: TopologicalLinkId; + +``` + +##### OUTPUT\_PARAMETERS + +-- none + +##### RAISED\_EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +topologicalLink: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +inv\_existingTopologicalLink + +"**topologicalLink** refers to *element* in the relationship where **layerND** refers to *containerLND*." + +inv\_noLinkConnection + +"**topologicalLink** shall not refer to any *containerLink* of a relationship." + +##### POST\_CONDITIONS + +inv\_noLink + +"**topologicalLink** does not refer to any *element* in the relationship." + +##### EXCEPTIONS + +-- none + +;} + +#### 7.3.2.13 Report topological link end creation + + + +OPERATION reportTopologicalLinkEndCreation { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +topologicalLinkEnd: TopologicalLinkEndId; +subnetwork: SubnetworkId; + +##### OUTPUT PARAMETERS + +-- none + +##### RAISED EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +topologicalLinkEnd: ; +subnetwork: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +-- none + +##### POST\_CONDITIONS + +inv\_existingLinkEnd + +"**topologicalLinkEnd** and **subnetwork** refer to *element* in the same relationship where **layerND** refers to *containerLND*." + +inv\_boundTopologicalLinkEnd +"**topologicalLinkEnd** refers to *transferCapacityLE* in the ** relationship where +**subnetwork** refers to *topologicalEntity*." + +##### EXCEPTIONS + +-- none + +;} + +#### 7.3.2.14 Report topological link end deletion + + + +OPERATION reportTopologicalLinkEndDeletion { + +##### INPUT\_PARAMETERS + +layerND: LayerNetworkDomainId; +topologicalLinkEnd: TopologicalLinkEndId; + +##### OUTPUT PARAMETERS + +-- none + +##### RAISED EXCEPTIONS + +-- none + +##### BEHAVIOUR + +##### SEMI-FORMAL + +##### PARAMETER\_MATCHING + +layerND: ; +topologicalLinkEnd: ; + +##### TRIGGERING\_CONDITIONS + +##### PRE\_CONDITIONS + +inv\_existingTopologicalLinkEnd + +"**topologicalLinkEnd** refers to *element* in the ** relationship where +**layerND** refers to *containerLND*." + +inv\_existingTopologicalLinkEndBinding + +"**topologicalLinkEnd** refers to *topologicalEntity* in the ** relationship." + +inv\_noNetworkCTPs + +"**topologicalLinkEnd** shall not refer to any *containerLE* in a ** relationship." + +##### POST\_CONDITIONS + +inv\_noTopologicalLinkEnd + +"**topologicalLinkEnd** does not refer to any *element* in the ** relationship +where **layerND** refers to *containerLND*." + +##### EXCEPTIONS + +-- none + +;} + +## 7.4 ASN.1 supporting productions + +In this specification, when an interface name is used within an ASN.1 production, the same label will be used, starting with a capital letter. The complete ASN.1 type definition for this query interface (e.g. use of ObjectIdentifier, INTEGER, ...) will be developed as part of the engineering viewpoint, with the concerned technology. + +``` + +AccessGroupId ::= CHOICE { + accessGroupQueryIfce TopmanAccessGroupQueryIfce + userIdentifer UserIdentifer}; +LayerNetworkDomainId ::= CHOICE { + layerNetworkDomainQueryIfce TopmanLayerNetworkDomainQueryIfce, + userIdentifer UserIdentifer }; +LinkEndChoice ::= CHOICE { + subnetwork SubnetworkId, + accessGroup AccessGroupId }; +LinkEndId ::= CHOICE { + linkEndQueryIfce TopmanLinkEndQueryIfce, + userIdentifer UserIdentifer }; +LinkId ::= CHOICE { + linkQueryIfce TopmanLinkQueryIfce, + userIdentifer UserIdentifer }; +ResourceChoice ::= CHOICE { + resourceId ResourceIfce, + userIdentifer SimpleNameType}; +SetOfNetworkTTPs ::= SET OF CHOICE { + networkTTPId TopmanNetworkTTPQueryIfce, + userIdentifer SimpleNameType} +SubnetworkId ::= CHOICE { + subnetworkQueryIfce TopmanSubnetworkQueryIfce, + userIdentifer UserIdentifer}; +TopologicalLinkEndId ::= CHOICE { + topologicalLinkEndQueryIfce TopmanTopologicalLinkEndQueryIfce, + userIdentifer UserIdentifer }; +TopologicalLinkId ::= CHOICE { + topologicalLinkQueryIfce TopmanTopologicalLinkQueryIfce, + userIdentifer UserIdentifer }; +UserIdentifer ::= SimpleNameType; + +``` + + + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.855.1-199903-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.855.1-199903-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..a7da83ecb82b51a4cef7694858eef2c35f1986ff --- /dev/null +++ b/marked/G/T-REC-G.855.1-199903-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:d77a478c5b78d330a2a6abbd32e7d0ac053d8b9c1ffe8a96476214afa6ddf7ae +size 8196 diff --git a/marked/G/T-REC-G.855.1-199903-I_PDF-E/af7916c89a458fdab6c3f443217388ae_img.jpg b/marked/G/T-REC-G.855.1-199903-I_PDF-E/af7916c89a458fdab6c3f443217388ae_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..8e170eb4ae05dab984a58ff0d265b70dfb7f9130 --- /dev/null +++ b/marked/G/T-REC-G.855.1-199903-I_PDF-E/af7916c89a458fdab6c3f443217388ae_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:f481fbd993883afb1da9a75b73d13795f19884b747e55e16ef6f00dd6883b955 +size 71940 diff --git a/marked/G/T-REC-G.855.1-199903-I_PDF-E/cab0834804fb031b43865554cc8d06ab_img.jpg b/marked/G/T-REC-G.855.1-199903-I_PDF-E/cab0834804fb031b43865554cc8d06ab_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..3d384be1297e2294fb74228e1c1afe4b35e4266e --- /dev/null +++ b/marked/G/T-REC-G.855.1-199903-I_PDF-E/cab0834804fb031b43865554cc8d06ab_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:283e69b1ea1e58ad31d50c27d290847c83ac6517a89bb571798baae57ce2f1b4 +size 83048 diff --git a/marked/G/T-REC-G.921-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.921-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..4a704a607d3bb814cb17721f6a2ef57b1c0dcc12 --- /dev/null +++ b/marked/G/T-REC-G.921-198811-I_PDF-E/raw.md @@ -0,0 +1,228 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt superimposed on it, and the letters 'ITU' in a bold, sans-serif font. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.921** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**DIGITAL SECTIONS AND DIGITAL LINE SYSTEMS** + +--- + +**DIGITAL SECTIONS BASED ON +THE 2048 kbit/s HIERARCHY** + +**ITU-T Recommendation G.921** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.921 was published in Fascicle III.5 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **DIGITAL SECTIONS BASED ON THE 2048 kbit/s HIERARCHY** + +*(Malaga-Torremolinos, 1984; amended at Melbourne, 1988)* + +## **1 Characteristics of digital sections** + +### 1.1 *General features* + +#### 1.1.1 *Bit rate* + +The digital sections based on the 2048 kbit/s hierarchy should be able to transmit signals at the nominal bit rates with their corresponding tolerances as indicated in Table 1/G.921. + +TABLE 1/G.921 + +##### **Tolerances on transmitted signals** + +| | | | | | +|---------------------------|------|------|--------|---------| +| Nominal bit rate (kbit/s) | 2048 | 8448 | 34 368 | 139 264 | +| Tolerance (ppm) | 50 | 30 | 20 | 15 | + +*Note - The 2048 kbit/s digital sections may be operating synchronously or plesiochronously within the same environment.* + +#### 1.1.2 *Special properties* + +The digital sections based on the 2048 kbit/s hierarchy should be bit sequence independent. + +### 1.2 *Characteristics of interfaces* + +The digital interfaces should comply with Recommendation G.703. + +### 1.3 *Performance standards* + +The performance requirements (e.g. errors, jitter and availability) are specified in terms of a Hypothetical Reference Digital Section (HRDS). Such a model is defined in Recommendation G.801. + +#### 1.3.1 *Error performance* + +Depending on the various applications in the different parts of a connection as specified in Recommendation G.821, different section quality classes have been defined in Table 2/G.921. + +#### 1.3.2 *Jitter* + +To ensure that the maximum network limit of jitter (see § 2 of Recommendation G.823) is not exceeded within a digital network it is necessary to control the jitter contributed by transmission systems. + +##### 1.3.2.1 Introduction + +The jitter specifications relate to hypothetical reference digital sections (HRDS) defined in Table 2/G.921. + +The limits given below have been derived on the basis that only a few digital sections will be connected in cascade and, moreover, no account has been taken of jitter originating from asynchronous multiplexing equipment. However, in certain real network configurations some Administrations may find it necessary to have more sections in cascade along with many asynchronous digital multiplex. For effective jitter control in these situations it might be necessary to satisfy more demanding limits and/or to use other means of jitter minimization. + +All the limits given below for digital sections are to be satisfied for all sections regardless of length and the number of repeaters. + +It is important to note that the limits must be met regardless of the transmitted signal. In such circumstances the choice for a test sequence is left to the discretion of national Administrations. The measurement guidelines given in § 4 of Recommendation G.823 should be taken into account. + +##### 1.3.2.2 Lower limit of tolerable input jitter + +The requirements given in Figure 2/G.823 and Table 2/G.823 should be met. + +*Note* - It is recognized that for 2048 kbit/s line sections and under practical conditions of interference the permissible maximum input jitter may have to be reduced in the frequency range $f_3$ to $f_4$ (but retaining the existing 20 dB/decade slope below the frequency $f_3$ which would result in a slightly lower value for frequency $f_2$ ). Considering that these sections are used in the lowest levels of the network and that actual 2048 kbit/s sources have very low output jitter in the high frequency range (cf. Recommendations G.732, G.742 and Q.551), the resulting performance will be entirely satisfactory. + +##### 1.3.2.3 Jitter transfer characteristics + +The maximum gain of the jitter transfer function should not exceed the value of 1 dB. + +*Note 1* - The low frequency limit should be as low as possible taking into account the limitations of measuring equipment. A value in the order of 5 Hz is considered acceptable. + +*Note 2* - For line sections at 2048 kbit/s complying with the alternative national interface option (Note 2 to Table 2/G.823), a jitter gain of 3 dB is permitted. + +TABLE 2/G.921 + +###### Digital section quality classifications for error performance + +| Section quality classification | HRDS length (km)
(see Figure 4/G.801) (Note 2) | Allocation
(Notes 3, 4) | To be used in circuit classification
(see Figure 1/G.821)
(Notes 5 and 6) | +|--------------------------------|---------------------------------------------------|----------------------------|---------------------------------------------------------------------------------| +| 1 | 280 | 0.45 % | High grade | +| 2 | 280 | 2 % | Medium grade | +| 3 | 50 | 2 % | Medium grade | +| 4 | 50 | 5 % | Medium grade | + +*Note 1* - There is no intention to confine any quality classification to any specific bit rate. The possibility of introducing additional options (for instance concerning length) requires further study. + +*Note 2* - The indicated values of length are those identified in Recommendation G.801. They should be understood to correspond to maximum lengths of real digital sections. If a real digital section is shorter, there will be no reduction of the bit error allocation (i.e. percentage value in the third column). This takes into account that: + +- in many line systems (especially on copper wire pairs) most bit errors occur at the ends of the system; +- in the interest of economy, short-haul systems may be designed with greater per-kilometre error ratio than long-haul systems. + +If a real digital section is longer (e.g. 450 km), its overall allocation should correspond to that of an integer number of HRDSs (of the same quality classification) the combined lengths of which are at least as long as the real section length (e.g. 2 x 280 km). + +*Note 3* - The values in this column are percentages of the overall degradation (at 64 kbit/s) specified in Recommendation G.821; i.e. of the 8% errored seconds, of the 10% degraded minutes and of the 0.1% severely errored seconds which are allocated according to the same rules as the two other parameters. + +*Note 4* - To obtain 64 kbit/s error performance data from error measurement at primary bit rates and above, the method described in Recommendation G.821, Annex D, should be used. + +*Note 5* - May also be used within a lower grade portion of the connection as defined per Figure 1/G.821. + +*Note 6* - To take account of adverse propagation conditions on radio systems as detailed in Recommendation G.821, an additional percentage of 0.05% of severely errored seconds has been allocated to a 2500 km radio-relay HRDP for systems operating in the high and medium grade quality part of the HRX. This corresponds for a 280 km section to a value of 0.0055% to be added to section quality classification 1 and 2 allocation when applied to severely errored seconds. + +This would result in an additional allowance of 0.025% of severely errored seconds available for the medium grade part of the connection if it is realized entirely with class 1 radio sections. Where the medium grade portion of the network is realized with a mixture of different classifications, part of this additional allowance may be allocated to classes 3 and 4 at the discretion of Administrations. + +To be consistent with the statistical assumptions made in G.821 § 3.3 b) regarding the number of radio sections in the HRX, and the occurrence of worst month effects it may be necessary to take into account the probability of worst month effects occurring simultaneously for all radio sections in a connection. A statistical model to be used for network planning and performance evaluation to assess the consistency of a given connection to the overall objective of G.821 is under study. + +##### 1.3.2.4 *Output jitter in the absence of input jitter* + +The maximum peak-to-peak jitter in the absence of input jitter, for any valid signal condition, should not exceed the limit given in Table 3/G.921. + +TABLE 3/G.921 + +###### **The maximum output jitter in the absence of input jitter for a digital section** + +(Measurements are made in accordance with the method shown in Figure 1/G.823) + +| Bit rate (kbit/s) | HRDS length (km) | Maximum output jitter for a digital section | | Measurement filter bandwidth | | | +|-------------------|------------------|---------------------------------------------------------------------|----------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------|-------------------|-----------| +| | | Low frequency limit ( $f_1$ - $f_4$ )
unit interval peak-to-peak | High frequency limit ( $f_3$ - $f_4$ )
unit interval peak-to-peak | Band-pass filter having a lower cut-off frequency $f_1$ or $f_3$ and an upper cut-off frequency $f_4$ | | | +| | | | | $f_1$ | $f_3$ | $f_4$ | +| 2 048 | 50 | 0.75 | 0.2 | 20 Hz | 18 Hz
(700 Hz) | 100 kHz | +| 8 448 | 50 | 0.75 | 0.2 | 20 Hz | 3 kHz
(80 kHz) | 400 kHz | +| 34 368 | 50 | 0.75 | 0.15 | 100 Hz | 10 kHz | 800 kHz | +| 34 368 | 280 | 0.75 | 0.15 | 100 Hz | 10 kHz | 800 kHz | +| 139 264 | 280 | 0.75 | 0.075 | 200 Hz | 10 kHz | 3 500 kHz | + +*Note* - For interfaces within national networks the frequency values ( $f_2$ and $f_3$ ) shown in parenthesis may be used. + +#### 1.3.3 *Availability* + +Under study. + +This performance requirement will be defined taking into account Recommendations G.821, E.800 and CCIR Recommendation 557. + +### 1.4 *Fault conditions and consequent actions* + +#### 1.4.1 *Fault conditions* + +The digital sections should detect the following fault conditions. + +##### 1.4.1.1 *Internal power failure of the line terminal equipment* + +*Note* - Line refers to both cable and radio-relay equipments. + +##### 1.4.1.2 *Error ratio > 1 · 10-3* + +The consequent actions should be taken when the bit error ratio is considered to exceed $1 \cdot 10^{-3}$ . Some form of persistence check should be employed to establish with appropriate confidence that a fault condition does exist. In any case, the alarm indication should be given with 500 ms of the start of the fault condition; this period includes the detection and any persistence check time. + +The alarm indication should be removed once it has been established, with appropriate confidence, that the fault condition has disappeared. + +##### 1.4.1.3 *Loss of the signal at the receiving terminal* + +*Note -* The detection of this fault condition is required only when it does not result in an indication "error ratio > $1 \cdot 10^{-3}$ ". + +##### 1.4.1.4 *Loss of alignment when alphabetic line codes or additional frames are used* + +*Note -* The detection of this fault condition is required only when it does not result in an indication "error ratio > $1 \cdot 10^{-3}$ ". + +##### 1.4.1.5 *Loss of incoming interface signal* + +#### 1.4.2 *Consequent action* + +Further to the detection of a fault condition, appropriate actions should be taken as specified in Table 4/G.921. + +TABLE 4/G.921 + +**Fault conditions and consequent actions for digital sections based on the 2048 kbit/s hierarchy** + +| Equipment | Fault conditions | Maintenance alarms | | AIS to | | +|-------------------------|----------------------------------------------------------------------------|--------------------|------------------------|----------------|----------------| +| | | prompt | deferred
(see Note) | Line side | Interface side | +| Line terminal equipment | Internal power failure | yes | | if practicable | if practicable | +| Line side only | Error ratio > $1 \cdot 10^{-3}$ | yes | | | yes | +| | Loss of the signal at the receiving terminal | yes | | | yes | +| | Loss of alignment when alphabetic line codes or additional frames are used | yes | | | yes | +| Interface side only | Loss of incoming signal | yes | | yes | | + +*Note -* As far as network performance objectives are concerned, criteria to activate deferred maintenance alarm are needed. They should be provided by the systems if possible. + +1.4.2.1 Prompt maintenance alarm indication generated to signify that performance is below acceptable standards and maintenance attention is required locally. + +*Note* - The location and provision of any visual and/or audible alarm activated by the alarm indications given in § 1.4.2.1 above, is left to the discretion of each Administration. + +1.4.2.2 AIS applied to the line side (see Notes 1 and 2). + +1.4.2.3 AIS applied to the interface side. + +*Note 1* - The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of ones. + +*Note 2* - The bit rate of this AIS should be within the tolerance limits defined in Table 1/G.921. + +*Note 3* - In the case of power failure apply AIS only if practicable. + +1.4.3 *Time requirements for application of AIS* + +In general, the AIS should be transmitted coincident with the detection of the fault conditions given in Table 4/G.921, except for AIS under the fault condition "error ratio $> 1 \cdot 10^{-3}$ "; in this latter case the time requirements given in § 1.4.1.2 should be respected. + +*Note* - For wholly national digital sections and, with the agreement of the countries involved digital sections which cross international boundaries, an option to delay the transmission of an AIS of up to a few seconds may be needed when the application of an AIS is controlled by means of a G.921 threshold monitoring process based on the severely errored second G.821 parameter. Short downstream alarms in international digital links which are routed via wholly national digital sections may appear during these few seconds. \ No newline at end of file diff --git a/marked/G/T-REC-G.950-198811-I_PDF-E/raw.md b/marked/G/T-REC-G.950-198811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..84574f18395ff90eaf259b0c6992b6132b14fb5a --- /dev/null +++ b/marked/G/T-REC-G.950-198811-I_PDF-E/raw.md @@ -0,0 +1,84 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.950** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**DIGITAL SECTIONS AND DIGITAL LINE SYSTEMS** + +--- + +**GENERAL CONSIDERATIONS ON DIGITAL +LINE SYSTEMS** + +**ITU-T Recommendation G.950** + +(Extract from the *Blue Book*) + +--- + +# NOTES + +1 ITU-T Recommendation G.950 was published in Fascicle III.5 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below). + +2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# **GENERAL CONSIDERATIONS ON DIGITAL LINE SYSTEMS** + +*(Malaga-Torremolinos, 1984; amended at Melbourne, 1988)* + +## **1 Introduction** + +Digital line systems are the means of providing digital line sections. Recommendations on digital line systems may recognize, for digital line sections operating at a given bit rate, specific transmission media and transmission techniques (e.g. coaxial cable, regenerative transmission, etc.). Performance requirements of digital line systems are for the guidance of systems designers and users (equipment design objectives) and may be related to hypothetical digital paths of defined constitution. + +All digital line systems operating on the same medium at a given bit rate shall comply with the characteristics of the digital line section at the same bit rate. + +## **2 General requirements for digital line systems** + +The following general requirements apply to all digital line systems on metallic pair cables and where applicable with appropriate interpretation, also to those on optical fibre cables. + +### **2.1 *Environmental conditions*** + +#### **2.1.1 *Climatic conditions*** + +Data concerning the classification of climatic stresses that can be expected for overground equipment is available in IEC Publication series No. 721. Conditions for underground equipment and further details for overground equipment need further study. + +*Note* - Supplement No. 34 contains some information on climatic conditions in underground repeater housing. + +#### **2.1.2 *Pressurization*** + +The repeaters of digital line systems may be operated in pressurized housings. + +#### **2.1.3 *Protection against induced voltages and currents caused by lightning and power lines, etc.*** + +The repeaters, line terminals and the power feeding arrangement should be protected against induced voltages and currents (caused by lightning or other sources) in accordance with Recommendation K.17. + +The system shall be physically protected from the above induced voltages and currents so that no damage is sustained. In addition, the performance of the system shall not be adversely affected by steady state induced voltages and currents although it may be affected by surges for the duration of the surge in certain circumstances. + +In addition the CCITT Directives [1] give guidance on these problems. + +#### **2.1.4 *Protection against interference from other sources*** + +The performance of Digital Line Systems should not be affected significantly by interference from sources within stations such as fluorescent lamp, tools, ventilation plant, etc., and especially sources giving rise to pulse type interference. Performance degradation due to interferences from radio and broadcast transmitters should also be prevented. + +*Note* - The Supplement No. 27 contains some information on possible measures to reduce effects from interference and measuring methods concerning interference. + +#### 2.1.5 *Interference to other systems* + +Conducted and radiated emissions must not interfere with other equipment, radio and broadcast services. In particular, digital line systems must coexist in the same cable with other digital and analogue line systems. (Some restrictions might, however, be necessary for joint use of different line systems on symmetrical pair cables.) + +## **Reference** + +- [1] CCITT Manual *Directives concerning the protection of telecommunication lines against harmful effects from electric power and electrified railway lines*, ITU, Geneva, 1988. \ No newline at end of file diff --git a/marked/G/T-REC-G.955-199611-I_PDF-E/1d3994bfe548ae7545d57df703e32a02_img.jpg b/marked/G/T-REC-G.955-199611-I_PDF-E/1d3994bfe548ae7545d57df703e32a02_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..6f772bb1da3a7181de99d9450e8f42c9cce55c65 --- /dev/null +++ b/marked/G/T-REC-G.955-199611-I_PDF-E/1d3994bfe548ae7545d57df703e32a02_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:ac499bb8a1cfcd1f625b27c0340f6774636b0f82ea67120f1fc6188976b9f372 +size 21320 diff --git a/marked/G/T-REC-G.955-199611-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg 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+version https://git-lfs.github.com/spec/v1 +oid sha256:e0e5b5545c1337859b8d38a0f644a8050eeb06abfff0d543ad8058a30015ccfa +size 28275 diff --git a/marked/G/T-REC-G.955-199611-I_PDF-E/raw.md b/marked/G/T-REC-G.955-199611-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..41e77fa829ece92e7daca01efaef291b336f9670 --- /dev/null +++ b/marked/G/T-REC-G.955-199611-I_PDF-E/raw.md @@ -0,0 +1,822 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.955** + +(11/96) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital sections and digital +line system – Digital line systems + +--- + +**Digital line systems based on the 1544 kbit/s +and the 2048 kbit/s hierarchy on optical fibre +cables** + +ITU-T Recommendation G.955 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| General | G.700–G.709 | +| Coding of analogue signals by pulse code modulation | G.710–G.719 | +| Coding of analogue signals by methods other than PCM | G.720–G.729 | +| Principal characteristics of primary multiplex equipment | G.730–G.739 | +| Principal characteristics of second order multiplex equipment | G.740–G.749 | +| Principal characteristics of higher order multiplex equipment | G.750–G.759 | +| Principal characteristics of transcoder and digital multiplication equipment | G.760–G.769 | +| Operations, administration and maintenance features of transmission equipment | G.770–G.779 | +| Principal characteristics of multiplexing equipment for the synchronous digital hierarchy | G.780–G.789 | +| Other terminal equipment | G.790–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| General aspects | G.800–G.809 | +| Design objectives for digital networks | G.810–G.819 | +| Quality and availability targets | G.820–G.829 | +| Network capabilities and functions | G.830–G.839 | +| SDH network characteristics | G.840–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +## **ITU-T RECOMMENDATION G.955** + +# **DIGITAL LINE SYSTEMS BASED ON THE 1544 kbit/s AND THE 2048 kbit/s HIERARCHY ON OPTICAL FIBRE CABLES** + +## **Summary** + +This Recommendation provides specifications for the transmission of optical signals based on both the 1544 kbit/s and 2048 kbit/s hierarchies. + +### **Source** + +ITU-T Recommendation G.955 was revised by ITU-T Study Group 15 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 8th of November 1996. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had/had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1997 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | | Page | +|-------|-------------------------------------------------------------|------| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Terms and definitions ..... | 2 | +| 4 | Abbreviations..... | 2 | +| 5 | Type of transmission medium..... | 3 | +| 6 | System margin ..... | 3 | +| 7 | System specifications..... | 4 | +| 7.1 | Regenerator section lengths ..... | 4 | +| 7.2 | Error performance..... | 5 | +| 7.3 | Receiver dynamic range..... | 9 | +| 7.4 | Optical source ..... | 9 | +| 7.5 | Operating wavelength range ..... | 9 | +| 7.6 | Optical path allowances for multimode fibre systems..... | 10 | +| 7.7 | Optical path allowances for single-mode fibre systems..... | 10 | +| 7.8 | Equipment margin ( $M_e$ ) ..... | 10 | +| 7.9 | Wavelength division multiplexing..... | 10 | +| 8 | Power feeding ..... | 11 | +| 9 | Systems for short haul applications ..... | 11 | +| 10 | Working conditions..... | 11 | +| 11 | Overall design features ..... | 11 | +| 12 | Maintenance strategy ..... | 12 | +| 12.1 | Type of supervision and fault location..... | 12 | +| 12.2 | Fault conditions and consequent actions..... | 12 | +| 13 | Safety considerations ..... | 12 | +| | Appendix I – Calculation of regenerator section length..... | 13 | +| I.1 | Approaches ..... | 13 | +| I.1.1 | Worst-case approach..... | 13 | +| I.1.2 | Statistical approach..... | 14 | +| I.1.3 | Semi-statistical approach..... | 15 | +| I.2 | Statistical data form ..... | 16 | +| I.3 | Examples..... | 16 | +| I.4 | An example of a statistical optical power budget..... | 16 | + + + +# **DIGITAL LINE SYSTEMS BASED ON THE 1544 kbit/s AND THE 2048 kbit/s HIERARCHY ON OPTICAL FIBRE CABLES1** + +*(revised in 1996)* + +# **1 Scope** + +This Recommendation covers digital line systems for the transmission of signals based on both the 1544 kbit/s and the 2048 kbit/s hierarchy on optical fibre cables and includes systems conveying the following bit rates: + +| | | +|--------------------|---------------------------| +| 2 048 kbit/s | 1 544 kbit/s | +| 8 448 kbit/s | 3 152 kbit/s | +| 34 368 kbit/s | 6 312 kbit/s | +| 139 264 kbit/s | 32 064 kbit/s | +| 4 × 139 264 kbit/s | 44 736 kbit/s | +| | $n \times 44\ 736$ kbit/s | +| | 97 728 kbit/s | +| | 4 × 97 728 kbit/s | + +The requirements for overall performance and interfaces of the corresponding digital sections are given in G.900-Series Recommendations. + +The aim of this Recommendation is to achieve longitudinal compatibility on elementary cable sections of different digital line systems, i.e. the possibility of installing digital line systems, produced by different manufacturers, on the same optical fibre cable. + +For the purpose of this Recommendation, optical fibre digital line systems can be represented as in Figure 1. The system may have no intermediate regenerators as in diagram a) of Figure 1, one intermediate regenerator as in diagram b) of Figure 1 or a larger number depending on the system design and route length. + +This Recommendation covers requirements for equipment intended to meet the relevant performance objectives of Recommendations G.821 and G.921 under all normally envisaged operating conditions. In any event, Recommendation G.821 remains the overriding performance objective of the network. + +# **2 References** + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- ITU-T Recommendation G.650 (1997), *Definition and test methods for the relevant parameters of single-mode fibres*. + +--- + +1 Recommendation G.955 totally replaces Recommendations G.955 and G.956 as contained in the *Blue Book*. + +- ITU-T Recommendation G.651 (1993), *Characteristics of a 50/125 µm multimode graded index optical fibre cable.* +- ITU-T Recommendation G.652 (1997), *Characteristics of a single-mode optical fibre cable.* +- ITU-T Recommendation G.653 (1997), *Characteristics of a dispersion-shifted single-mode optical fibre cable.* +- ITU-T Recommendation G.654 (1997), *Characteristics of a cut-off shifted single-mode optical fibre cable.* +- CCITT Recommendation G.703 (1991), *Physical/electrical characteristics of hierarchical digital interfaces.* +- ITU-T Recommendation G.821 (1996), *Error performance of an international digital connection operating at a bit rate below the primary rate and forming part of an integrated services digital network.* +- CCITT Recommendation G.921 (1988), *Digital sections based on the 2048 kbit/s hierarchy.* +- CCITT Recommendation G.950 (1988), *General considerations on digital line systems.* +- ITU-T Recommendation G.957 (1995), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy.* +- IEC 479, *Effects of current on human beings and livestock, Part 1 (1994) – General aspects; Part 2 (1987) – Special aspects.* +- IEC 825 (1993), *Safety of laser products, Part 1 – Equipment classification, requirements and user's guide; Part 2 – Safety of optical fibre communication systems.* + +# 3 Terms and definitions + +This Recommendation defines the following terms: + +**3.1 longitudinal compatibility:** The capability of installing digital line systems, produced by different manufacturers on the same optical fibre cable. + +**3.2 cable margin:** See 6.1. + +**3.3 equipment margin:** See 6.2. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|----------------|---------------------------| +| BER | Bit Error Ratio | +| C | Connector | +| FWHM | Full-Width Half-Maximum | +| ISI | Inter-Symbol Interference | +| LED | Light-Emitting Diode | +| M c | Cable Margin | +| M e | Equipment Margin | +| MLM | Multi-Longitudinal Mode | +| N/A | Not Applicable | +| OFA | Optical Fibre Amplifier | + +| | | +|-----|-----------------------------------| +| PDF | Probability Distribution Function | +| REG | Regenerator | +| Rx | Receiver | +| SLM | Single Longitudinal Mode | +| Tx | Transmitter | + +# 5 Type of transmission medium + +Multimode optical fibres conforming to Recommendation G.651 or single-mode optical fibres conforming to Recommendations G.652, G.653 and G.654 are considered suitable for these systems. Operation may be in the region of either 850 nm, 1310 nm or 1550 nm or some other wavelength depending on the fibre and system type employed. The attenuation considered the most appropriate for operation at the various bit rates and wavelengths will be chosen by the Administrations in relation to the characteristics of the link to be realized and in accordance with this Recommendation. Similarly, splice losses, connector losses and the cable margin must be chosen together with the attenuation of the optical fibre in order to achieve the overall attenuation specified in clause 7. + +# 6 System margin + +For the purpose of this Recommendation, the total system margin [see diagram a) of Figure 1], or regenerator section margin [see diagram b) of Figure 1], is subdivided into two main contributions. The disposition of these margins is shown in Figure 2. + +![Figure 1/G.955: System margin diagrams. Diagram a) shows a transmitter (TX) connected to a receiver (RX) via an optical fibre with a splice. Diagram b) shows a transmitter (TX) connected to a regenerator (REG) and then to a receiver (RX) via optical fibres with splices. Points T, T', C, S, and R are marked along the optical path.](367926125450c2bc3f4bdca9d59a62ba_img.jpg) + +Figure 1/G.955 consists of two diagrams, a) and b), illustrating system margin points in optical communication links. + +Diagram a) shows a Transmitter (TX) connected to a Receiver (RX) via an optical fibre. The TX is connected to an optical fibre at point C (Connector). Point S (Splice) is located on the optical fibre just after the TX. Point R (Receiver) is located on the optical fibre just before the RX. The RX is connected to the optical fibre at point C (Connector). The TX and RX are connected to equipment interfaces T and T' respectively. + +Diagram b) shows a Transmitter (TX) connected to a Regenerator (REG) and then to a Receiver (RX) via optical fibres. The TX is connected to an optical fibre at point C (Connector). Point S (Splice) is located on the optical fibre just after the TX. Point R (Receiver) is located on the optical fibre just before the REG. The REG is connected to the optical fibre at point C (Connector). Point S (Splice) is located on the optical fibre just after the REG. Point R (Receiver) is located on the optical fibre just before the RX. The RX is connected to the optical fibre at point C (Connector). The TX and RX are connected to equipment interfaces T and T' respectively. + +T, T' Equipment interface in accordance with Recommendation G.703. + S Point on the optical fibre just after the Transmitter (TX) or the Regenerator (REG) optical Connector (C). + R Point on the optical fibre just before the Receiver (RX) or the Regenerator (REG) optical Connector (C). + +NOTE – Additional connectors at a distribution frame (if used) are considered to be part of fibre link and to be located between points S and R. + +Figure 1/G.955: System margin diagrams. Diagram a) shows a transmitter (TX) connected to a receiver (RX) via an optical fibre with a splice. Diagram b) shows a transmitter (TX) connected to a regenerator (REG) and then to a receiver (RX) via optical fibres with splices. Points T, T', C, S, and R are marked along the optical path. + +Figure 1/G.955 + +![Figure 2/G.955: Block diagram of a regenerator section. The diagram shows a sequence of components from left to right: a transmitter (TX) with two right-pointing arrows inside, connected to a connector (C) at point T'. This is followed by a splice (S), a fiber optic cable symbol (circle with a diagonal arrow), a cable margin block (Mc), a connector (R), another connector (C), an equipment margin block (Me), and a receiver (RX) ending at point T. Points T', C, S, R, C, and T are labeled above the line.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +``` + +graph LR + T_prime((T')) --- TX[TX] + TX --- C1(C) + C1 --- S(S) + S --- Fiber((/)) + Fiber --- Mc[Mc] + Mc --- R(R) + R --- C2(C) + C2 --- Me[Me] + Me --- RX[RX] + RX --- T((T)) + +``` + +Figure 2/G.955: Block diagram of a regenerator section. The diagram shows a sequence of components from left to right: a transmitter (TX) with two right-pointing arrows inside, connected to a connector (C) at point T'. This is followed by a splice (S), a fiber optic cable symbol (circle with a diagonal arrow), a cable margin block (Mc), a connector (R), another connector (C), an equipment margin block (Me), and a receiver (RX) ending at point T. Points T', C, S, R, C, and T are labeled above the line. + +T1507400-92 + +NOTE – $M_e$ represents the total combined equipment impairments from both transmitter and receiver. + +**Figure 2/G.955** + +**6.1 cable margin ( $M_c$ ):** The cable margin, $M_c$ , covers allowances for: + +- i) future modifications to the cable configuration (additional splices, increased cable lengths, etc.); +- ii) fibre cable performance variations due to environment factors; and +- iii) degradation of any connector between points S and R when provided. + +**6.2 equipment margin ( $M_e$ ):** The equipment margin, ( $M_e$ ), covers allowances for the effect of time and environmental factors on equipment performance (e.g. transmitter launched power, receiver sensitivity, equipment connector degradations). + +NOTE 1 – The design margin, which covers the allowance for the tolerances on the characteristics of the various components of the system, is not considered because worst-case values for such characteristics are reflected in the specifications of clause 7. + +NOTE 2 – The system margin is in relation to a BER threshold of $1 \times 10^{-10}$ even though for practical reasons the measurements of receiver sensitivity may be carried out at other thresholds. + +NOTE 3 – The approaches adopted in this Recommendation leave some additional margin in operating systems which can be considered as an unallocated margin. + +# 7 System specifications + +The optical link of a regenerator section can be represented as in Figure 2 from the point of the system specifications. + +As a minimum requirement for maximum section length of typical commercially available systems, the transmitter and the receiver shall be designed so that the error performance requirements of 7.2 are obtained with an optical path as defined in 7.6 or 7.7. + +## 7.1 Regenerator section lengths + +The regenerator section length achievable with the systems specified in this Recommendation is related to the fibre characteristics and the specific capabilities of the transmitter/receiver equipment. + +Examples are given in Appendix I. + +For multimode systems, the description of the baseband response with a single value (the $-3$ dB optical bandwidth) may not be sufficient to determine the suitability of the fibre for the specified system. In some cases, a more detailed description of this characteristic or the description of the impulse response may be necessary. Additionally, the overall $-3$ dB optical bandwidth is assumed to include modal and chromatic contributions. + +For single-mode systems, a principle characteristic is that, for a given section length, they exhibit less pulse broadening than multimode systems, provided that the central wavelength of the laser is sufficiently close to the fibre's zero-dispersion wavelength. + +In general, for single-mode fibre systems employing laser sources operating near or below a nominal bit rate of $6 \times 44\,736$ kbit/s, the regenerator section length is expected to be limited by loss and not by dispersion. At higher bit rates, the regenerator section length may be limited by dispersion. Therefore, it is desirable to check whether a regenerator section length is limited by loss or dispersion: + +- *Loss-limited systems:* The loss-limited regenerator section length can be calculated taking into account the system gain, the loss introduced by the sum of connector and splice losses, fibre attenuation at the operating wavelength, cable margin, and the additional loss due to any dispersion penalty (including mode partition noise). +- *Dispersion-limited systems:* The dispersion-limited regenerator section length is dependent upon the receiver tolerance to pulse distortion (e.g. due to the transmitter source spectral characteristics, mode partition noise, and the fibre chromatic dispersion). The determination of section length should be consistent with Recommendation G.651 for multimode fibre systems, and with Recommendation G.957 for single-mode fibre systems. + +## 7.2 Error performance + +The transmitter and receiver shall be designed so that a BER not worse than $1 \times 10^{-10}$ is obtained when operating over an optical path between points S and R corresponding to the relevant values given in Table 1 for multimode fibre systems and Table 2 for single-mode fibre systems. + +**Table 1/G.955 – Recommended optical path allowances for digital line systems on multimode optical fibre conforming to Recommendation G.651 with a single optical transmission signal** + +| Nominal bit rate (kbit/s) | Nominal wavelength (nm) | Source type | Allowances between S and R at $1 \times 10^{-10}$ BER | | +|---------------------------|-------------------------|-------------|-------------------------------------------------------|-----------------------------------------------| +| | | | Maximum attenuation (dB) | Minimum overall –3 dB optical bandwidth (MHz) | +| 2 048 | 850 | Laser | 51 | 10 | +| | | LED | a) | 10 | +| | 1 310 | Laser | 46 | 10 | +| | | LED | 30 | 10 | +| 6 312 | 850 | Laser | 47 | 17 | +| | | LED | 34 | 17 | +| | 1 310 | Laser | 34 | 17 | +| | | LED | 21 | 17 | +| 8 448 | 850 | Laser | 47 | 20 | +| | | LED | a) | a) | +| | 1 310 | Laser | a) | a) | +| | | LED | a) | a) | +| 32 064 | 850 | Laser | a) | a) | +| | | LED | a) | a) | +| | 1 310 | Laser | 33 | 65 | +| | | LED | a) | a) | +| 34 368 | 850 | Laser | 41 | 50 | +| | | LED | a) | a) | +| | 1 310 | Laser | 35 | 50 | +| | | LED | 22 b) | 50 | +| 44 736 | 850 | Laser | 42 | 62 | +| | | LED | 29 | 62 | +| | 1 310 | Laser | 33 | 62 | +| | | LED | 21 | 62 | +| $2 \times 44\ 736$ | 850 | Laser | 42 | 90 | +| | | LED | a) | a) | +| | 1 310 | Laser | 30 | 81 | +| | | LED | a) | a) | + +**Table 1/G.955 – Recommended optical path allowances for digital line systems on multimode optical fibre conforming to Recommendation G.651 with a single optical transmission signal (*concluded*)** + +| Nominal bit rate (kbit/s) | Nominal wavelength (nm) | Source type | Allowances between S and R at $1 \times 10^{-10}$ BER | | +|---------------------------|-------------------------|-------------|-------------------------------------------------------|-----------------------------------------------| +| | | | Maximum attenuation (dB) | Minimum overall –3 dB optical bandwidth (MHz) | +| 97 728 | 850 | Laser | a) | a) | +| | 850 | LED | a) | a) | +| | 1 310 | Laser | 31 | 100 | +| | 1 310 | LED | a) | a) | +| $3 \times 44\,736$ | 850 | Laser | a) | a) | +| | 850 | LED | a) | a) | +| | 1 310 | Laser | 28 | 120 | +| | 1 310 | LED | a) | a) | +| 139 264 | 850 | Laser | 35 | 100 | +| | 850 | LED | a) | a) | +| | 1 310 | Laser | 27 | 100 | +| | 1 310 | LED | 18 b) | 100 | + +a) Values under study. + +b) Provisional value. + +NOTE 1 – The description of the baseband response with a single value (the –3 dB optical bandwidth) may not be sufficient to determine the suitability of the fibre for the specified system. A quasi-Gaussian impulse response may be assumed for design purposes but a more detailed description of the fibre response may be necessary in some cases. + +NOTE 2 – In the case of LED systems for the values given in the table, the optical fibre is assumed to have a nominal numerical aperture of 0.20 to 0.21. Additionally, the overall –3 dB optical bandwidth (modal and chromatic) is assumed to be measured with an optical source having a maximum linewidth (FWHM) of 60 nm and 100 nm centred at 850 nm and 1310 nm respectively. + +NOTE 3 – Values given in this table are for source types other than Single Longitudinal Mode (SLM) lasers. + +NOTE 4 – Refer to 7.1, Regenerator section lengths, for other considerations. + +**Table 2/G.955 – Recommended optical path allowances for digital line systems on single-mode optical fibre conforming to Recommendation G.652 with a single optical transmission signal** + +| Nominal bit rate (kbit/s) | Nominal wavelength (nm) | Source type | Allowances between S and R at $1 \times 10^{-10}$ BER | | +|---------------------------|-------------------------|-------------|-------------------------------------------------------|-----------------------------------| +| | | | Maximum attenuation (dB) | Maximum dispersion ps/nm (Note 1) | +| 2 048 | 1 310 | Laser | 46 | N/A | +| | 1 550 | | a) | a) | +| 8 448 | 1 310 | Laser | 40 | N/A | +| | 1 550 | | a) | a) | +| 34 368 | 1 310 | Laser | 35 | N/A (MLM) | +| | 1 550 | | a) | a) | +| 44 736 | 1 310 | Laser | 32 | N/A (MLM) | +| | 1 550 | | a) | a) | +| 97 728 | 1 310 | Laser | 31 | a) | +| | 1 550 | | a) | a) | +| $3 \times 44 736$ | 1 310 | Laser | 28 | N/A (MLM) | +| | 1 550 | | a) | a) | +| 139 264 | 1 310 | Laser | 28 | 215 (MLM) (Note 4) | +| | 1 550 | | 28 | a) | +| $4 \times 44 736$ | 1 310 | Laser | 26 | N/A (MLM) | +| | 1 550 | | a) | a) | +| $6 \times 44 736$ | 1 310 | Laser | 26 | (Note 2) | +| | 1 550 | | a) | a) | +| $4 \times 97 728$ | 1 310 | Laser | 28 | (Note 2) | +| | 1 550 | | a) | a) | +| $9 \times 44 736$ | 1 310 | Laser | 26 | (Note 2) | +| | 1 550 | | a) | a) | +| $12 \times 44 736$ | 1 310 | Laser | 24 | (Note 2) | +| | 1 550 | | a) | a) | +| $4 \times 139 264$ | 1 310 | Laser | 24 | 92 (MLM) (Note 3) | +| | 1 550 | | 24 (Note 5) | a) | +| $18 \times 44 736$ | 1 310 | Laser | 24 | (Note 2) | +| | 1 550 | | a) | a) | +| $24 \times 44 736$ | 1 310 | Laser | 24 | (Note 2) | +| | 1 550 | | a) | a) | +| $36 \times 44 736$ | 1 310 | Laser | 23 | (Note 2) | +| | 1 550 | | a) | a) | + +**Table 2/G.955 – Recommended optical path allowances for digital line systems on single-mode optical fibre conforming to Recommendation G.652 with a single optical transmission signal (concluded)** + +a) Values under study. + +N/A Not Applicable. + +NOTE 1 – The reference to MLM- or SLM-lasers is related to a minimum condition for the indicated dispersion limit. In case of MLM-lasers, SLM-lasers should not be precluded. + +NOTE 2 – Regenerator section lengths may be dispersion-limited. Specific values are dependent upon several factors and require further study. Refer to 7.1, Regenerator section lengths, for other considerations. + +NOTE 3 – This value indicates the maximum permissible dispersion for $4 \times 139\,264$ kbit/s systems at the limits of the operating wavelength range specified (1300 and 1325 nm). The system supplier will need to determine any resultant design penalty considering the effect of mode partition noise, chromatic dispersion, etc., due to the spectral characteristics of the optical source. + +NOTE 4 – This value indicates the maximum permissible dispersion for 139 264 kbit/s system at the limit of the operating wavelength range specified (1280 to 1335 nm). + +NOTE 5 – There are several network situations in which the need arises for increasing regenerator span length value of $4 \times 140$ Mbit/s systems at 1550 nm with respect to $4 \times 140$ Mbit/s systems at 1310 nm (already installed). In these cases an available attenuation higher than 24 dB between points S and R could be required. This requirement arises from the need to use existing network infrastructure (e.g. repeater cabinets built for existing 1310 nm $4 \times 140$ Mbit/s systems). + +NOTE 6 – The maximum attenuation values may be increased in certain cases by future use of optical fibre amplifiers (OFAs). Details are for further study. + +## **7.3 Receiver dynamic range** + +The optical receiver dynamic range should automatically accommodate a range of input levels to compensate for equipment production tolerances, cable attenuation ranges and tolerances, and the effects of temperatures and ageing. + +It is desirable that the dynamic range of the receiver should also minimize the need for line building out attenuators. + +## **7.4 Optical source** + +Multimode systems may employ either lasers or light-emitting diodes as sources. Single-mode systems generally employ lasers, although light-emitting diodes may have specific applications at certain bit rates. Single-mode systems using light-emitting diodes require further study. + +## **7.5 Operating wavelength range** + +The nominal wavelengths of 850 nm and 1310 nm imply possible use anywhere in the range 820 to 910 nm and 1280 to 1335 nm respectively, for systems operating up to and including 140 Mbit/s. For systems at higher nominal bit rates, the 1310 nm range is reduced to 1285 to 1330 nm. The range for the region around 1550 nm is under study. + +It may be noted that operating wavelengths of 1310 nm and 1550 nm correspond to optical frequencies of about 229 THz and 193 THz, respectively. + +NOTE 1 – For single-mode systems operating in the 1310 nm range, the lower wavelength limit is determined from consideration of dispersion and cut-off wavelength effects, while the upper wavelength limit is due to consideration of dispersion and attenuation. In particular it should be noted that the range quoted in this Recommendation is restricted compared to the dispersion range of 1271 to 1360 nm quoted in Recommendation G.652 because of the possibility of OH peak-related excess losses. To ensure satisfactory system operation, the cut-off wavelength of the shortest length of cabled fibre in a single-mode elementary cable section must not exceed the operating wavelength. The second order ( $LP_{11}$ ) mode should be sufficiently attenuated along the fibre such that at the detector modal noise and bimodal dispersion effects are negligible. + +NOTE 2 – The nominal wavelength ranges specified above are for LEDs and Multi-longitudinal Mode (MLM) lasers. Single Longitudinal Mode (SLM) lasers require further study. + +## **7.6 Optical path allowances for multimode fibre systems** + +The optical path allowances between points S and R are given in Table 1 for multimode fibre systems employing LEDs or MLM lasers. These allowances include the cable margin, $M_c$ , and comprise the overall attenuation and 3 dB optical bandwidth. + +These allowances represent the worst-case parameter values derived from current practice within which a given system can be designed. Trade-offs among bandwidth, attenuation, dispersion, coding, etc. can vary these parameters. + +The calculation of attenuation between points S and R should consider the variation of the optical fibre loss over the actual wavelength range of the optical source. + +## **7.7 Optical path allowances for single-mode fibre systems** + +The optical path allowances between points S and R are given in Table 2 for single-mode fibre systems employing LEDs or MLM lasers. These allowances include the cable margin $M_c$ and comprise the overall attenuation and dispersion. + +These allowances represent the worst-case parameter values derived from current practice within which a given system can be designed. Trade-offs among attenuation, dispersion, coding, etc. can vary these parameters. + +The calculation of attenuation between points S and R should consider the variation of the optical fibre loss over the actual wavelength range of the optical source. + +## **7.8 Equipment margin ( $M_e$ )** + +The equipment margin as defined in 6.2 depends on the system characteristics, the environmental conditions and the maintenance strategy. Administrations will need to choose a suitable value in cooperation with the system supplier for their applications. + +A minimum margin of 3 dB is considered appropriate for systems using temperature stabilized lasers and PIN detectors, which operate in a typical station environment. + +Greater margins may be necessary in systems using light-emitting diodes or non-temperature stabilized lasers, or in systems operating in an outdoor environment. + +## **7.9 Wavelength division multiplexing** + +The requirements for digital line systems employing wavelength division multiplexing techniques operating either within the same wavelength region or in separate wavelength regions are under study. + +It may be noted that an optical wavelength interval of 1 nm corresponds to an optical frequency of about 175 GHz and 125 GHz at 1310 nm and 1550 nm, respectively. + +# **8 Power feeding** + +The use of dependent regenerative repeaters is not generally required for optical fibre systems. It is not, therefore, necessary to recommend a specific remote power feeding system. + +Where remote power feeding is required for specific applications, only constant current d.c. feeding should be used. + +Where local power feeding is required, a d.c.-voltage is sufficient. + +Precautions must be taken to protect staff from any possible danger arising from the normal operating voltages and remote power feed currents as well as from induced voltages and currents. Appropriate safety measures should be adopted to ensure that under abnormal conditions the requirements of IEC 479 are met. + +Precautions are also needed for the protection of the equipment against induced voltages and currents. + +NOTE – Precautions against induced voltages and currents require further study. The K-Series Recommendations may be relevant to this study. + +# **9 Systems for short haul applications** + +The allowances for digital line systems found in Tables 1 and 2 are aimed at specifying minimum requirements for transmission systems with maximized section lengths. However, for applications not requiring maximized section lengths, more economical equipment can be used. Parameters for such equipment may differ from those in Tables 1 and 2 by allowing trade-offs to be made. + +Furthermore, remote power feeding and remote supervision of intermediate regenerators may not be necessary. + +# **10 Working conditions** + +See Recommendation G.950. + +# **11 Overall design features** + +Three possible approaches for the design of the elementary cable section are a worst-case design, a statistical design, and a semi-statistical design. + +The worst-case approach gives an absolute confidence that the required performances between points S and R will be met, at the expenses of a more conservative regenerator section length. + +The statistical approach is based on designing an enhanced regenerator section, but admits a predetermined possibility of insufficient optical path allowances between point S and R. In this way a cost saving can be achieved in long-haul, high-bit-rate optical systems through the reduction of the number of repeaters. + +When using the statistical approach, the sub-system parameters can be expressed in terms of their statistical distributions, which need to be available from the manufacturers. Such distributions can be handled either numerically (e.g. by Montecarlo or mapping methods) or analytically (e.g. Gaussian averages and standard deviations). + +Examples of parameters which can be considered statistical in nature are the following: + +- cable attenuation; +- cable chromatic dispersion (zero-dispersion wavelength and zero-dispersion slope); + +- splice and connector losses; +- transmitter spectral characteristics (central wavelength, spectral width, etc.); +- available system gain between points S and R (e.g. optical power available at point S and receiver sensitivity at point R. These parameters may need to be considered separately for transverse compatibility considerations). + +According to design practices, each of the above parameters can be considered either statistical or worst-case. + +In a semi-statistical approach, those parameters assumed deterministic may be given a zero-width distribution around the worst-case value (see Appendix I). + +In general, the statistical consideration of the cable attenuation coefficient, dispersion coefficient and splice loss is particularly significant for the advantages taken from statistical and semi-statistical design approach. The choice of deterministic or statistical parameters is based on the experience of the particular administration/operator. + +# 12 Maintenance strategy + +## 12.1 Type of supervision and fault location + +In-service monitoring or out-of-service fault location can be used. For bit rates equal to or above 139 264 kbit/s, in-service monitoring is recommended. In the absence of suitable metallic conductors in the optical cable the supervision of the intermediate regenerator, where appropriate, should be provided by the same two optical fibres used for the line systems. + +## 12.2 Fault conditions and consequent actions + +The following fault conditions should be detected in addition to those specified in Recommendation G.821 for the relevant digital sections, and the associated consequent actions should be taken: + +- failure of remote power feeding* (if applicable) + - A prompt maintenance alarm should be generated, if practicable. +- low error ratio threshold exceeded* + - This threshold is $1 \times 10^{-5}$ for systems up to 8448 kbit/s and $1 \times 10^{-6}$ for systems at higher bit rates. + +A deferred maintenance alarm should be generated to signify that performance is deteriorating. + +Furthermore, for systems with a laser, means to detect laser deterioration are considered advisable. For this fault condition, a deferred maintenance alarm indication is considered adequate. + +# 13 Safety considerations + +IEC Standard 825 or appropriate national standards on laser safety may be used for guidance in this area. + +Automatic laser shutdown may also be employed to achieve necessary standards for safety. + +# APPENDIX I + +## Calculation of regenerator section length + +### I.1 Approaches + +In general, three possible approaches can be defined in multimode and single-mode optical fibre system design: + +- worst-case approach (purely deterministic); +- statistical approach (all parameters are statistically defined); +- semi-statistical approach (only some parameters are statistically defined). + +#### I.1.1 Worst-case approach + +This approach consists of considering the worst possible values for all design parameters of the repeater span. This approach penalizes the achievable span length with respect to statistical or semi-statistical combination of design parameters, but guarantees in 100% of cases, over the lifetime of the system, an attenuation and a dispersion between points S and R lower than the specified system values. + +In this approach, the regenerator section length can be calculated considering that for a specified application at the end of the optical path between points S and R (see Figure 2) the overall attenuation should not exceed the specified value. + +The optical path attenuation between points S and R is evaluated according to: + +$$P_T - A_{tot} - P_D - M_e - P_R \geq 0$$ + +The optical path attenuation satisfies also: + +$$A_{tot} = (\alpha_c + \alpha_m) \cdot L + (N - 1) \cdot l_s + N_c \cdot l_c$$ + +where: + +- $P_T$ is the transmitted power at point S (dBm); +- $A_{tot}$ is the total attenuation allowable between points S and R (dB); +- $P_D$ is the dispersion power penalty (dB); +- $M_e$ is the equipment margin (dB); +- $P_R$ is the received power at point R (dBm); +- $\alpha_c$ is the cable attenuation coefficient (dB/km); +- $\alpha_m$ is the cable margin coefficient (dB/km); +- $L$ is the total length of fibre cable (km); +- $N$ is the number of cable factory length in the repeater section; +- $l_s$ is the splice loss (dB); +- $N_c$ is the number of connectors between points S and R; +- $l_c$ is the connector loss (dB). + +The optical total length of cable satisfies: + +$$L \leq \frac{P_T - P_R - P_D - M_e - (N - 1) \cdot l_s - N_c \cdot l_c}{\alpha_c + \alpha_m}$$ + +Concerning chromatic dispersion of single-mode fibre in order to obtain the regenerator section length defined by the power budget and to respect the overall limit defined in Tables 1 and 2, one defines the dispersion power penalty. + +This penalty ( $P_D$ ) contains effects of Inter-Symbol Interference (ISI), mode partition noise (for MLM lasers) and wavelength chirping (for SLM lasers). + +For additional information on the calculation of elementary cable section lengths, refer to Recommendation G.651. + +Concerning the bandwidth for multimode fibre, in order to obtain the regenerator section length defined by the power budget and to respect the overall limit defined in Tables 1 and 2, the following condition has to be satisfied (see 3/G.651). + +$$B_T = [B_{MODAL}^{-2} + B_{CHROMATIC}^{-2}]^{1/2}$$ + +For additional information on the calculation of bandwidth for elementary cable section, refer to Recommendation G.651. + +#### I.1.2 Statistical approach + +In this approach, the statistic distributions of each parameters design, which influence the attenuation and dispersion of regenerator section length, are considered. + +In general, the parameters which can be considered statistical in nature are the following: + +- cable attenuation; +- splice loss; +- connector loss; +- zero-dispersion wavelength; +- zero-dispersion slope; +- operating wavelength; +- optical power available at the transmitter; +- receiver sensitivity; +- equipment improvements. + +With this approach, the design, starting from the characteristics of statistical distribution, consists in defining a statistical confidence level (e.g. 99%) by which it is possible to satisfy the attenuation and dispersion limits imposed in the regeneration section length. + +When using the statistical approach, the sub-system parameters are expressed in terms of statistical distributions, which are assumed to be available from the manufacturers or from data obtained from equipment production facilities. Such distributions can be handled either analytically (e.g. convolution functions or Gaussian averages and standard deviations) or numerically (e.g. by Montecarlo method or mapping methods). Applying convolution functions, the Probability Distribution Functions (PDF) of all design parameters existing between the optical transmitter and the optical receiver have to be known. + +The design of optical transmission path involves the convolution of the PDFs of all the relevant parameters. This method requires more computation effort than the analytical one but will provide a more accurate estimation of the performance of real systems. + +If all parameters have Gaussian statistical distributions, a simple design process may be used considering for each one mean value ( $\mu$ ) and standard deviation ( $\sigma$ ). + +The formulae to be implemented for this approach need further study. + +Some of the design parameters cannot be assumed to have Gaussian distributions (e.g. splice attenuation). However, in this case, we can consider the following hypotheses: + +- 1) The mean values and standard deviations are representative of the parameters over time and sample sizes are sufficient to warrant the use of Gaussian statistical theory. +- 2) The parameter distributions are reasonably Gaussian in shape. +- 3) All connector and splice losses are uncorrelated with fibre losses. +- 4) The loss allowance associated with transmitter wavelength drift is correlated in different reels. +- 5) Cable losses, except those associated with transmitter wavelength variation, are correlated over the mean reel length but are uncorrelated from reel to reel. +- 6) All cables are represented by the same statistics. + +Assuming that mean values plus two sigma (standard deviation) are less than the worst-case values, it is possible to invoke a valid statistical method, with a simple analytic method, in 97.7% of cases. + +Nevertheless, in a very small percentage of cases, it is possible that attenuation or dispersion between points S and R is larger than specified system values. In these cases, it will be necessary to sacrifice part of the system margin or selecting source and receiver to overcome power budget and/or dispersion limit problems. However, the remedies produce several problems of logistic and operating nature. + +#### **I.1.3 Semi-statistical approach** + +Considering the previous statistical approach, the parameters relating to fibres and passive devices can confidently be considered statistical; on the other hand, parameters such as optical transmitter power and receiver sensitivity should not be considered on a statistical basis, because deterministic values of these parameters are set in the factory and because this Recommendation specifications are recommended in terms of allowable attenuation and dispersion between points S and R. However, statistical data could be generated from production measurements. + +In this situation, the semi-statistical approach considers some parameters in a deterministic way (worst-case), as, for example, operating wavelength, optical power available at the transmitter and receiver sensitivity. For other parameters (as fibre attenuation coefficient, splice loss, etc.), statistical distributions are considered, with suitable statistical parameters (e.g. mean value, standard deviation, skewness). + +For example a semi-statistical method can use a set of values distributed according to Gaussian distribution generated through a Montecarlo algorithm starting from the factory statistical values (e.g. mean value, standard deviation, skewness). This set of values is used to evaluate the total dispersion and the total attenuation over the repeater section. The calculation is iterated a number $N$ of times. A number of iterations equal to 100 gives a statistical confidence level better than 99% relating to the largest regenerator section length at which the allowable attenuation and dispersion limits between points S and R are not exceeded. A three-term Sellmeier equation is used to calculate the total dispersion, at the wavelength of interest, over the regenerator section. + +As regards total attenuation, the power budget is calculated taking into account the relationship reported in the worst-case approach (see I.1.1). + +### I.2 Statistical data form + +One form is shown in Table I.1 which may be used to record statistical data. In this form, besides the parameters mean values and standard deviations, the distribution type is required where possible for further information. + +**Table I.1/G.955 – Statistical data form** + +| Parameter | Unit | Worst-case approach | Statistical approach | | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------|---------------------|----------------------|----------|-------------------| +| | | | $\mu$ | $\sigma$ | Distribution type | +| $P_T$ | dBm | | | | | +| $P_R$ | dBm | | | | | +| $P_D$ | dBm | | | | | +| $\lambda$ | nm | | | | | +| $\Delta\lambda$ | nm | | | | | +| $l_c$ | dB | | | | | +| $a_c$ | dB | | | | | +| $l_s$ | dB | | | | | +| $\lambda_0$ | nm | | | | | +| $s_0$ | ps/(nm 2 · km) | | | | | +| $P_T$ Transmitted power at point S – Transmitted power can be controlled to be within the specified limits throughout its working life. Margin is accounted for in the standard deviation.
$P_R$ Input optical power at point R that is necessary to achieve a specified bit-error ratio.
$\lambda$ Source operating central wavelength.
$P_D$ Dispersion power penalty (dB) due to inter-symbol interference, mode partition noise and chirping.
$\Delta\lambda$ Source spectral width.
$l_c$ Connector loss.
$a_c$ Cable loss (at ambient temperature) at the end of cable lifetime and at the transmitter's nominal central wavelength.
$l_s$ Splice loss at ambient temperature.
$\lambda_0$ Zero-dispersion wavelength of the fibre.
$s_0$ Zero-dispersion slope of the fibre. | | | | | | + +### I.3 Examples + +For further study. + +### I.4 An example of a statistical optical power budget + +This clause gives an example of an optical power budget for a hypothetical rather than any particular system. Statistical convolution is applied to the equipment components only, the outside plant between points S and R is not included in the analysis. Rather than manipulating mean and standard deviation values of the individual budget components, all parameters are represented as frequency – histograms based on a common 0.1 dB magnitude increment. The overall result is then obtained by direct convolution of these components. + +Two typical distributions are shown in Figure I.1. + +![Histogram of Receiver sensitivity (dBm) distribution.](e9f324c9d7f5305a55cb156855e95b95_img.jpg) + +Relative frequency of occurrence + +Mean value: -50.5 dBm +Standard deviation: 0.218 dBm + +-51.2 -51.0 -50.8 -50.6 -50.4 -50.2 -50.0 -49.8 -49.6 -49.4 -49.2 -49.0 -48.8 + +Receiver sensitivity (dBm) + +This histogram shows the distribution of receiver sensitivity in dBm. The x-axis ranges from -51.2 to -48.8 dBm with major tick marks every 0.2 dBm. The y-axis represents the relative frequency of occurrence. The distribution is roughly bell-shaped, centered around -50.5 dBm. The mean value is -50.5 dBm and the standard deviation is 0.218 dBm. + +Histogram of Receiver sensitivity (dBm) distribution. + +![Histogram of Optical connector loss (dB) distribution.](9b5411fa2d169b66f6185fbf67b49766_img.jpg) + +Relative frequency of occurrence + +Mean value: 0.4 dB +Standard deviation: 0.202 dB + +0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 + +T1507410-92 + +Optical connector loss (dB) + +This histogram shows the distribution of optical connector loss in dB. The x-axis ranges from 0 to 2.4 dB with major tick marks every 0.2 dB. The y-axis represents the relative frequency of occurrence. The distribution is roughly bell-shaped, centered around 0.4 dB. The mean value is 0.4 dB and the standard deviation is 0.202 dB. A small code 'T1507410-92' is visible near the bottom right of the x-axis. + +Histogram of Optical connector loss (dB) distribution. + +**Figure I.1/G.955 – Typical parameter distribution histograms** + +Table I.2 shows the budget for the hypothetical system including the worst-case (extreme) and typical (mean) values taken from the eleven system parameter distributions. Direct arithmetic summation of these values gives the worst-case and typical system margins of 39.05 and 41.80 dB, respectively. + +**Table I.2/G.955 – Hypothetical system power budgets** + +| | | Worst case | Typical case | +|----|------------------------------------------------|-------------------|---------------------| +| 1 | Average transmitted power | –2.95 dBm | –2.65 dBm | +| 2 | Receiver sensitivity | –50.05 dBm | –50.50 dBm | +| | Available power ratio | 47.10 dB | 47.85 dB | +| | System impairments | | | +| 3 | Source variations with temperature and time | 0.95 dB | 0.74 dB | +| 4 | Receiver variations with temperature and time | 2.45 dB | 2.04 dB | +| 5 | Reflection effects | 0.05 dB | 0.05 dB | +| 6 | Pattern dependant and equalisation impairments | 0.95 dB | 0.85 dB | +| 7 | Transmitter pulse imperfections | 0.45 dB | 0.39 dB | +| 8 | Extinction-ratio and dispersion effects | 0.65 dB | 0.54 dB | +| 9 | Error-rate correction | 0.65 dB | 0.65 dB | +| 10 | Transmitter connector loss | 0.95 dB | 0.40 dB | +| 11 | Receiver connector loss | 0.95 dB | 0.40 dB | +| | Total impairments | 8.05 dB | 6.05 dB | +| | | | | +| | System margin | 39.05 dB | 41.80 dB | + +Figure I.2 shows the result of the statistical analysis; in particular, it gives the system margin as a function of probability of occurrence. + +For example, point "A" in Figure I.2 shows that a system margin of 40.4 dB will be achieved with a probability of 999 cases in 1000. + +Note that the form of the overall system margin probability distribution is nearly Gaussian despite the non-Gaussian form of the individual parameter distributions as shown in Figure I.2. + +Any deterministic parameter, such as No. 9, the "error-rate adjustment", is represented in the distribution table as a single-column histogram 0.1 dB wide. + +![Graph of Log (distribution function) vs System margin (dB). The curve starts at (39, -10) and levels off at 0. A point 'A' is marked at approximately (40.5, -2.5).](645bea0b27d63e4a9a300af5793ae7d2_img.jpg) + +Log (distribution function) + +System margin (dB) + +Graph of Log (distribution function) vs System margin (dB). The curve starts at (39, -10) and levels off at 0. A point 'A' is marked at approximately (40.5, -2.5). + +![Graph of Probability density function vs System margin (dB). The curve is a bell shape centered at approximately 41.8 dB. The x-axis is labeled from 39 to 49 dB.](1d3994bfe548ae7545d57df703e32a02_img.jpg) + +Probability density function + +System margin (dB) + +T1507420-92 + +Graph of Probability density function vs System margin (dB). The curve is a bell shape centered at approximately 41.8 dB. The x-axis is labeled from 39 to 49 dB. + +**Figure I.2/G.955 – Probability distribution of system margin** + +# ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|----------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communication | +| Series Z | Programming languages | \ No newline at end of file diff --git a/marked/G/T-REC-G.962-199303-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg 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DIGITAL SECTION FOR ISDN PRIMARY RATE AT 1544 kbit/s** + +**ITU-T Recommendation G.963** + +(Previously "CCITT Recommendation") + +--- + +# FOREWORD + +The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecommunication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +ITU-T Recommendation G.963 was prepared by the ITU-T Study Group XVIII (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). + +# --- NOTES + +1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. + +In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms "CCITT, CCIR, or IFRB" or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. + +2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# CONTENTS + +*Page* + +| | | | +|------------|----------------------------------------------------------------------------------------|----| +| 1 | General ..... | 1 | +| 1.1 | Scope ..... | 1 | +| 1.2 | Configuration ..... | 1 | +| 1.3 | Application ..... | 2 | +| 1.4 | Abbreviations ..... | 3 | +| 2 | Modelling and relationship between the digital section and the ET ..... | 3 | +| 3 | Functions ..... | 3 | +| 3.1 | B-channel ..... | 3 | +| 3.2 | H0-channel ..... | 5 | +| 3.3 | H11-channel ..... | 5 | +| 3.4 | D-channel ..... | 5 | +| 3.5 | Bit timing ..... | 5 | +| 3.6 | Octet timing ..... | 6 | +| 3.7 | Frame alignment ..... | 6 | +| 3.8 | CRC procedure ..... | 6 | +| 3.9 | Power feeding ..... | 6 | +| 3.10 | Operations and maintenance ..... | 6 | +| 4 | Network performance ..... | 6 | +| 4.1 | Availability ..... | 6 | +| 4.2 | Signal transfer delay ..... | 6 | +| 4.3 | Error performance ..... | 6 | +| 4.4 | Jitter ..... | 7 | +| 5 | Operations and maintenance ..... | 7 | +| 5.1 | General ..... | 7 | +| 5.2 | Control facilities ..... | 7 | +| 5.3 | Monitoring ..... | 10 | +| 6 | Operation and maintenance procedures ..... | 12 | +| 6.1 | General ..... | 12 | +| 6.2 | 4 kbit/s data link ..... | 13 | +| 6.3 | Partitioning of functions ..... | 15 | +| 6.4 | Definitions of signals at the T reference point ..... | 18 | +| 6.5 | Definition of FEs at the V3 reference point ..... | 18 | +| 6.6 | PH and MPH primitives ..... | 21 | +| 6.7 | Digital section (DS) state machine ..... | 21 | +| 6.8 | Definition of ET layer 1 state machine ..... | 24 | +| Annex A | – System management requirements ..... | 26 | +| A.1 | Introduction ..... | 26 | +| A.2 | System management requirements ..... | 26 | +| Appendix I | – Transmission algorithm of performance report messages at NT1 based on option 2 ..... | 29 | + + + +# ACCESS DIGITAL SECTION FOR ISDN PRIMARY RATE AT 1544 kbit/s + +(Helsinki, 1993) + +# 1 General + +## 1.1 Scope + +This Recommendation describes the characteristics of the primary rate access digital section at 1544 kbit/s between the user network interface (at the T reference point, defined in Recommendation I.411) and the local exchange (at the V3 reference point, defined in Recommendation Q.512) supporting the 1544 kbit/s primary rate interface structures defined in Recommendation I.412 and the required additional functions. + +In this Recommendation and unless otherwise indicated, the term TE is used to indicate terminating layer 1 aspects of TE1, TA and NT2 functional groups. + +When the term TE indicates terminating layer 1 aspects of TE1, then according to Figure 2/I.411, the S and T reference points coincide. + +The terminology used in this Recommendation is contained in Recommendations I.112 and G.701. + +## 1.2 Configuration + +Figure 1 shows the boundaries of the access digital section in relation to the digital transmission system. + +![Diagram showing the boundaries of the 1544 kbit/s primary rate access digital section and digital transmission system. It includes components TE, NT1, LT, and ET, with reference points T and V3 marked.](4d7f667796a8cdcdd745e953ac11e289_img.jpg) + +The diagram illustrates the network configuration for a 1544 kbit/s primary rate access. It shows four main components connected in a linear sequence: TE (Terminating Equipment), NT1 (Network Termination 1), LT (Line Termination), and ET (Exchange Termination). The TE is connected to the NT1 at the 'T reference point'. The NT1 is connected to the LT via a dashed line. The LT is connected to the ET at the 'V3 reference point'. Above the NT1 and LT, a double-headed arrow labeled '1544 kbit/s primary rate access digital transmission system (Note)' indicates the scope of the transmission system. Below the T and V3 reference points, another double-headed arrow labeled '1544 kbit/s primary rate access digital section' indicates the scope of the access digital section. The text 'T1814670-92/d01' is located at the bottom right of the diagram. + +Diagram showing the boundaries of the 1544 kbit/s primary rate access digital section and digital transmission system. It includes components TE, NT1, LT, and ET, with reference points T and V3 marked. + +NOTE – The 1544 kbit/s primary rate access digital transmission system refers to either a line system using metallic media or optical fibres, or radio systems. + +FIGURE 1/G.963 +The 1544 kbit/s primary rate access digital section and digital transmission system boundaries + +The concept of an access digital section is used in order to allow a functional and procedural description and a definition of network requirements. + +NOTE – From a functional point of view, the information transferred acrosss reference points T and V3 is different and therefore the 1544 kbit/s primary rate access digital section may not be symmetrical. + +The concept of a digital transmission system is used in order to describe the characteristics of an implementation using a specific medium in support of the access digital section. + +NOTE – The T and V3 reference points are defined in Recommendations I.411 and Q.512, respectively. + +## 1.3 Application + +The 1544 kbit/s primary rate access digital section may be applied as given in Figure 2 for: + +- direct access to the local exchange (V3 reference point); +- access via higher order multiplex equipment to the local exchange. + +![Figure 2/G.963: Examples of equipment configurations in the ISDN subscriber primary rate access at 1544 kbit/s. The diagram shows two configurations. The top configuration shows a direct access path from a Terminal Equipment (TE) through an NT1 to a Local Terminal (LT) at reference point V3, labeled as the '1544 kbit/s primary rate access digital section'. The bottom configuration shows a more complex path where two TE/NT1/LT units connect to a Multiplexer (MUX). The path from the first LT to the MUX is labeled as the '1544 kbit/s primary rate access digital section'. The path between the MUX and a second LT is labeled as a 'Digital link'. The second LT connects to another MUX, which then connects to an Exchange Terminal (ET) at reference point V3'. The entire path from the first LT to V3' is labeled as a 'Digital access link'. Reference points T and V3 are marked at the beginning of the sections. A note 'T1817070-92/d02' is at the bottom right.](1d27fed9c01eb99f6535283f35fe3bbf_img.jpg) + +Figure 2/G.963: Examples of equipment configurations in the ISDN subscriber primary rate access at 1544 kbit/s. The diagram shows two configurations. The top configuration shows a direct access path from a Terminal Equipment (TE) through an NT1 to a Local Terminal (LT) at reference point V3, labeled as the '1544 kbit/s primary rate access digital section'. The bottom configuration shows a more complex path where two TE/NT1/LT units connect to a Multiplexer (MUX). The path from the first LT to the MUX is labeled as the '1544 kbit/s primary rate access digital section'. The path between the MUX and a second LT is labeled as a 'Digital link'. The second LT connects to another MUX, which then connects to an Exchange Terminal (ET) at reference point V3'. The entire path from the first LT to V3' is labeled as a 'Digital access link'. Reference points T and V3 are marked at the beginning of the sections. A note 'T1817070-92/d02' is at the bottom right. + +#### NOTES + +- 1 1544 kbit/s primary rate access digital sections may include one or more regenerators. +- 2 Multiple applications of digital links and multiplexors are possible. + +FIGURE 2/G.963 +Examples of equipment configurations in the ISDN subscriber primary rate access +at 1544 kbit/s + +## 1.4 Abbreviations + +A number of abbreviations are used in this Recommendation, some of which are commonly used in the ISDN reference configuration while others have been created only for this Recommendation, as follows: + +| | | +|------|---------------------------------------------------| +| DS | (1544 kbit/s Primary Rate) access Digital Section | +| FE | Function Element used between ET and LT | +| SIG | SIGnal between LT and NT1 | +| DL | 4 kbit/s Data Link (m-bits) | +| PRM | Performance Report Message | +| HDLC | High level Data Link Control procedures | + +# 2 Modelling and relationship between the digital section and the ET + +The general model shown in Figure 3 depicts the whole ISDN customer access layer 1 and adjacent entities and provides the basis to describe the functions performed by the DS and those performed by TE, ET and system management and how various functions are grouped. In particular, according to this model the maintenance functions specified in this Recommendation are not confined to functions performed by the DS but include functions associated with ET layer 1. + +This model includes primitive procedures between ET layer 1 and ET layer 2 and between ET layer 1 and system management: + +- I.431 to Q.920/Q.921 interactions between ET layer 1 and ET layer 2 and between ET layer 1 and system management based on PH and MPH primitives, respectively, as defined in Recommendation I.431. These interactions are for the support of functions specified in Recommendations Q.920 and Q.921; +- interactions between ET layer 1 and system management for the support of functions associated with the DS, based on MPH primitives. + +The primitive procedures within TE comply with the specification according to Recommendation I.431. + +This model does not constrain layer 1 arrangements between LT and NT1, or the primary rate access digital transmission system technology. + +# 3 Functions + +For each direction of transmission of the DS the following shall be provided: + +- 24 time-slots at 64 kbit/s for the transport of any appropriate allocation of the following: B-, H0-, and H11-channels; +- 1 time-slot at 64 kbit/s within 24 time-slots for the transport of a D-channel when this channel is present; +- 8 kbit/s for frame alignment, and to follow the procedure for multiframe alignment, CRC, and the utilization of the m-bits, as described in Recommendations G.704 and G.706. + +Figure 4 shows the functions which must be supported by the DS. + +## 3.1 B-channel + +This function provides for the bidirectional transmission of independent B-channel signals each having a bit rate of 64 kbit/s as defined in Recommendation I.412. + +![General model of ISDN customer access layer 1 and adjacent entities diagram. The diagram shows the flow of signals and primitives between a Terminal Equipment (TE) and an External Terminal (ET) through an NT1 and an LT. The TE consists of Layer 2 and Layer 1. Layer 2 connects to Layer 1 via B Channels. Layer 1 connects to the NT1 via Signals (T). The NT1 connects to the LT via SIGs (Note 2). The LT connects to the ET via elements (FEs) (Note 2) and V3. The ET also consists of Layer 2 and Layer 1. Layer 2 connects to Layer 1 via B Channels. Layer 1 connects to the line system via MPH-primitives according to I.431 and MPH-primitives associated with line system. System management (Note 3) is shown at both ends, with PH-primitives and MPH-primitives according to I.431. A 1544 kbit/s primary rate access digital transmission (Note 1) is indicated between the NT1 and the LT. A 1544 kbit/s primary rate access digital section is indicated between the TE Layer 1 and the ET Layer 1.](2ee59e629035d641140e55f4d215b0d7_img.jpg) + +General model of ISDN customer access layer 1 and adjacent entities diagram. The diagram shows the flow of signals and primitives between a Terminal Equipment (TE) and an External Terminal (ET) through an NT1 and an LT. The TE consists of Layer 2 and Layer 1. Layer 2 connects to Layer 1 via B Channels. Layer 1 connects to the NT1 via Signals (T). The NT1 connects to the LT via SIGs (Note 2). The LT connects to the ET via elements (FEs) (Note 2) and V3. The ET also consists of Layer 2 and Layer 1. Layer 2 connects to Layer 1 via B Channels. Layer 1 connects to the line system via MPH-primitives according to I.431 and MPH-primitives associated with line system. System management (Note 3) is shown at both ends, with PH-primitives and MPH-primitives according to I.431. A 1544 kbit/s primary rate access digital transmission (Note 1) is indicated between the NT1 and the LT. A 1544 kbit/s primary rate access digital section is indicated between the TE Layer 1 and the ET Layer 1. + +T1814770-92/d03 + +#### NOTES + +- 1 The digital transmission system refers to either a digital line transmission system using metallic media or optical fibres, or radio systems. +- 2 SIGs, FEs and primitives refer to an exchange of information. They do not imply any specific implementation. Some of these functions may be terminated in the LT and then would not pass the digital transmission system. +- 3 The term "system management" corresponds to both system and layer management as defined in Recommendation Q.940. + +FIGURE 3/G.963 +General model of ISDN customer access layer 1 and adjacent entities + +![Diagram of 1544 kbit/s primary rate access digital section functions between T and V3 reference points.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg) + +The diagram illustrates the functions of a 1544 kbit/s primary rate access digital section. It is bounded by a 'T reference point' on the left and a 'V3 reference point' on the right. The functions are listed in a vertical stack within a central box: + +- B-, H0- or H11-channels +- 1 D-channel 64 kbit/s (Note 1) +- Bit timing +- Octet timing +- Frame alignment +- CRC procedures (Note 3) +- Power feeding (Note 2) +- Operations & Maintenance + +Double-headed arrows connect each function to both the T and V3 reference points, except for 'Power feeding' which has a single-headed arrow pointing from the T reference point. The diagram is labeled 'T1814780-92/d04' at the bottom right. + +Diagram of 1544 kbit/s primary rate access digital section functions between T and V3 reference points. + +#### **NOTES** + +- 1 Provided when this channel is present. +- 2 This power feeding function is optional. Only NT1 may be powered from the interface at the T reference point (see Recommendation I.431). +- 3 The generation, monitoring, or termination of the CRC bits is optional. + +FIGURE 4/G.963 + +#### **Functions** + +## **3.2 H0-channel** + +This function provides for the bidirectional transmission of independent H0-channel signals each having a bit rate of 384 kbit/s as defined in Recommendation I.412. + +## **3.3 H11-channel** + +This function provides for the bidirectional transmission of an H11-channel signal having a bit rate of 1536 kbit/s as defined in Recommendation I.412. + +## **3.4 D-channel** + +This function provides for the bidirectional transmission of a D-channel signal having a bit rate of 64 kbit/s as defined in Recommendation I.412. + +## **3.5 Bit timing** + +This function provides bit (signal element) timing to enable the TE or NT and LT or ET to recover information from the aggregate bit stream. + +## **3.6 Octet timing** + +This function provides 8 kHz timing for TE or NT and LT or ET to enable an octet structure for voice coders and for other timing purposes as required. + +## **3.7 Frame alignment** + +This function provides information to enable the TE or NT and LT or ET to recover the time-division multiplexed channels. + +## **3.8 CRC procedure** + +This function protects against false framing and may provide for error performance monitoring of the access digital section. This includes the multiframe procedure defined in Recommendation G.704. + +## **3.9 Power feeding** + +This optional function feeds power to NT1 via the user network interface in accordance with Recommendation I.431. + +## **3.10 Operations and maintenance** + +This optional function supports required actions and information for operating and maintaining the DS controlled by the ET as defined in Recommendation I.604. The function is conveyed by a bidirectional 4 kbit/s data link transported in the m-bits. + +Four categories of functions have been identified: + +- commands regarding LT, regenerator, or NT1; +- information from LT, regenerator, or NT1; +- indications of defect conditions; +- indications of access digital section power feeding status. + +# **4 Network performance** + +## **4.1 Availability** + +The definition of availability is given in Annex A/G.821. The availability objective of the DS should be consistent with the availability requirement for the hypothetical reference digital section as given in Recommendations G.801 and I.350. + +## **4.2 Signal transfer delay** + +Signal transfer delay is specified for B-channels and is defined as absolute signal delay between T and V3 reference points for each direction of transmission. The value shall be less than 2 ms when systems are implemented using metallic media, optical fibres, or a radio relay system. The application of a satellite system in the DS is also possible; however, for speech services, Recommendation G.114 may limit such an application until appropriate methods to control double satellite hops and switching of echo control devices are available. These methods are outside the scope of this Recommendation. + +In case of remote application of the DS (see Figure 2 with a digital link between the DS and the ET) the signal transfer delay is defined for the DS between the T and V3 reference points. + +## **4.3 Error performance** + +Error performance must be consistent with the requirements given in Recommendation G.821, local grade. + +## 4.4 Jitter + +### 4.4.1 Output/input jitter at the T reference point + +The requirements are defined in 4.5/I.431. + +### 4.4.2 Jitter at the V3 reference point + +The input jitter limits are described in Recommendation G.824. + +NOTE – If models described in Figure 2 are used to connect a customer to the ET, jitter reduction is not required at V3. + +# 5 Operations and maintenance + +## 5.1 General + +This subclause describes the operations and maintenance functions for the DS. + +Further assumptions regarding system management are given in Annex A. The maintenance functions defined in Recommendation I.604 provide the capability to maintain the DS to the level of network performance given in 4. + +It must be possible to test and maintain the DS in accordance with Recommendation I.604 regardless of the subscriber installation. + +The main features are: + +- a) control of maintenance and test support facilities; +- b) monitoring of the function elements to provide operating and performance information and fault condition indications; +- c) maintenance communication facility. + +## 5.2 Control facilities + +### 5.2.1 Loopbacks + +Loopbacks are maintenance tools used to assist in locating faults in the network. This specification covers loopback 1, 1A and 2 (see Recommendation I.604), all of which are complete loopbacks. Loopbacks are controlled by the codewords specified in Table 2. + +#### 5.2.1.1 Loopback implementation + +The various loopbacks are summarized below, and illustrated in Figure 5. + +- 1) Loopback 1 is located within the LT. It loops the 1544 kbit/s signal back to the ET. +- 2) Loopback 1A is located within the regenerator. It loops the 1544 kbit/s signal back to the ET. +- 3) Loopback 2 is located within the NT1 and loops the 1544 kbit/s signal (line loopback) or 1536 kbit/s signal (payload loopback) back to the ET. Loopback 2 may be implemented as a line loopback or as a payload loopback depending on whether the NT1 terminates framing. + +NOTE – Line loopback shall result in a full 1544 kbit/s loopback back to the interface of the received bit stream. Bit sequence integrity shall be maintained. + +A payload loopback is implemented only in equipment that terminates framing of the primary rate access line. The signal looped back to the received signal is 1536 kbit/s. The framing bits are originated at the loopback point. The payload loopback shall maintain bit sequence integrity for the information bits; however, the payload loopback need not maintain the integrity of eight-bit time slots, frames, or multi-frames. + +![Diagram of the 1544 kbit/s access digital section showing loopbacks. The section is divided into three main components: NT1, REG, and LT. On the left, a TE (Terminal Equipment) is connected to the NT1. On the right, an ET (Exchange Terminal) is connected to the LT. The NT1, REG, and LT are connected in series. Each component has a loopback mechanism: Loopback 2 at the NT1, Loopback 1A at the REG, and Loopback 1 at the LT. AIS (Alarm Indication Signal) arrows show the flow of signals between components and loopbacks. A bracket at the top labeled 'Access digital section' spans the NT1, REG, and LT components. The diagram is labeled T1814790-92/d05 at the bottom right.](d4af765160d04ecef538e5066006dc77_img.jpg) + +Diagram of the 1544 kbit/s access digital section showing loopbacks. The section is divided into three main components: NT1, REG, and LT. On the left, a TE (Terminal Equipment) is connected to the NT1. On the right, an ET (Exchange Terminal) is connected to the LT. The NT1, REG, and LT are connected in series. Each component has a loopback mechanism: Loopback 2 at the NT1, Loopback 1A at the REG, and Loopback 1 at the LT. AIS (Alarm Indication Signal) arrows show the flow of signals between components and loopbacks. A bracket at the top labeled 'Access digital section' spans the NT1, REG, and LT components. The diagram is labeled T1814790-92/d05 at the bottom right. + +FIGURE 5/G.963 +**Loopbacks associated with the 1544 kbit/s access digital section** + +#### 5.2.1.2 Loopback procedure + +The loopback control conforms with Recommendation I.604. + +A normal call set-up request cannot override a request for loopback 1, 1A or 2. + +A sequence for the loopback procedure when controlled by the ET system management is: + +- ET generates an operation command for the required loopback; +- ET receives loopback operation acknowledgement; +- ET performs the test; +- ET generates a release command; +- ET receives a loopback release indication. + +Activation of loopback shall be a two step process, as follows: + +- ET issues a loopback activate code 10 times in 160 consecutive m-bit positions; +- the requested loopback is activated when the loopback activate code is detected at least 5 times and is no longer detected. + +This procedure is applicable to options 1, 2 and 4 defined in Recommendation I.604. Refer to Figures 6, 7 and 8 for description to the options 1, 4 and 2, respectively. + +Whenever a loopback is activated, AIS shall be sent forward as a replacement for the looped signal. + +Loopbacks shall be deactivated upon receipt of any one (or combination) of the following: + +- The loopback deactivate codeword; +- AIS; +- a data link message consisting of two occurrences of the one-per-second PRM separated by uninterrupted idle code. + +![Diagram of an access digital section using Option 1 NT1. It shows a TE (Terminal Equipment) on the left and an ET (Exchange Terminal) on the right connected by a 'Digital link'. The TE contains a CRC monitor (M) and a CRC generator (G). The ET contains a CRC generator (G) and a CRC monitor (M). Solid lines represent mandatory connections, and dashed lines represent optional connections. Labels T and V3 are at the bottom of the diagram. Reference T1814800-92/d06 is in the bottom right.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +— Mandatory + Optional + +- L Local CRC error information +- R Remote CRC error information +- M CRC monitor +- G CRC generator + +Diagram of an access digital section using Option 1 NT1. It shows a TE (Terminal Equipment) on the left and an ET (Exchange Terminal) on the right connected by a 'Digital link'. The TE contains a CRC monitor (M) and a CRC generator (G). The ET contains a CRC generator (G) and a CRC monitor (M). Solid lines represent mandatory connections, and dashed lines represent optional connections. Labels T and V3 are at the bottom of the diagram. Reference T1814800-92/d06 is in the bottom right. + +FIGURE 6/G.963 +**Access digital section using Option 1 NT1** +**(No CRC processing)** + +![Diagram of an access digital section using Option 4 NT1. It shows a TE on the left, an NT1 (Network Terminal 1) in the middle, and an ET on the right connected by a 'Digital link'. The NT1 contains a CRC monitor (M), a storage for network side monitor (SN), and a storage for user side monitor (SU). The TE contains a CRC monitor (M) and a CRC generator (G). The ET contains a CRC generator (G) and a CRC monitor (M). Solid lines represent mandatory connections, and dashed lines represent optional connections. Labels T and V3 are at the bottom of the diagram. Reference T1814810-92/d07 is in the bottom right.](eefe19c5e14dc4d6c316b7f7fbb7d7d7_img.jpg) + +— Mandatory + Optional + +- L Local CRC error information +- R Remote CRC error information +- M CRC monitor +- G CRC generator +- SN Storage for network side monitor +- SU Storage for user side monitor + +Diagram of an access digital section using Option 4 NT1. It shows a TE on the left, an NT1 (Network Terminal 1) in the middle, and an ET on the right connected by a 'Digital link'. The NT1 contains a CRC monitor (M), a storage for network side monitor (SN), and a storage for user side monitor (SU). The TE contains a CRC monitor (M) and a CRC generator (G). The ET contains a CRC generator (G) and a CRC monitor (M). Solid lines represent mandatory connections, and dashed lines represent optional connections. Labels T and V3 are at the bottom of the diagram. Reference T1814810-92/d07 is in the bottom right. + +FIGURE 7/G.963 +**Access digital section using Option 4 NT1** +**(CRC monitoring in the NT1)** + +![Diagram of a digital link section showing TE, NT1, LT, and ET components with CRC monitoring paths. The diagram illustrates the flow of operational frames and PRMs between a Terminal Equipment (TE) and an Exchange Terminal (ET) via an NT1 and a Line Terminal (LT). CRC monitoring is performed using CRC monitors (M) and CRC generators (G). PRMs are categorized into network, ET, TE, and user types. The legend defines the symbols for Local (L) and Remote (R) CRC error information, CRC monitors (M), CRC generators (G), operational frames, mandatory PRMs, and optional PRMs.](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +① PRMnetwork + ② PRMET + ③ PRMTE + ④ PRMuser + +L Local CRC error information + R Remote CRC error information + M CRC monitor + G CRC generator + Operational frame with active associated CRC bits + PRMs (mandatory) + PRMs (optional) + +Diagram of a digital link section showing TE, NT1, LT, and ET components with CRC monitoring paths. The diagram illustrates the flow of operational frames and PRMs between a Terminal Equipment (TE) and an Exchange Terminal (ET) via an NT1 and a Line Terminal (LT). CRC monitoring is performed using CRC monitors (M) and CRC generators (G). PRMs are categorized into network, ET, TE, and user types. The legend defines the symbols for Local (L) and Remote (R) CRC error information, CRC monitors (M), CRC generators (G), operational frames, mandatory PRMs, and optional PRMs. + +NOTE – See Table 4. + +FIGURE 8/G.963 +Access digital section using Option 2 NT1 +(CRC processing in the NT1) + +## 5.3 Monitoring + +### 5.3.1 Functions + +The following operational conditions are monitored throughout the section: + +- a) the defect conditions; +- b) the transmission performance; +- c) the power feed status (optional). + +### 5.3.2 Anomaly and defect conditions and consequent actions + +#### 5.3.2.1 Anomaly and defect conditions + +The DS shall detect the following anomalies or defects: + +From the user side and the exchange side of the DS: + +- loss of power at NT1 (optional); +- loss of incoming signal; +- loss of frame alignment (see Recommendations G.706 and I.431); +- CRC error (optional). + +NOTE – DS equipment (NT1, LT ... ) must detect loss of incoming signal or loss of frame alignment (option 2 only) and must generate downstream (to reference point V3) the fault indication signal AIS. + +#### 5.3.2.2 Detection of anomaly and defect indication signals + +Unless otherwise noted, the following anomaly and defect indications shall be detected under options 2 and 4 only: + +- a) Within the access digital section: + - loss of incoming signal or loss of frame alignment (options 1, 2 and 4 apply); + - CRC error; + - excessive CRC errors; + - CRC error information (optional in option 4); + - loss of power at NT1 (optional); + - AIS at line side of NT1. +- b) At the interface at the T reference point: + - loss of incoming signal or loss of frame alignment (options 1, 2 and 4 apply); + - CRC error; + - excessive CRC errors; + - CRC error information (optional in option 4); + - loss of power feeding (optional). +- c) At the interface at the V3 reference point: + - loss of incoming signal (options 1, 2 and 4 apply). + +#### 5.3.2.3 Consequent actions + +The actions that the DS must take after defect detection or defect indication detection are given in Table 5 (see 6.7.2). + +Failure indication information (RAI and AIS) is automatically transmitted from the DS to the ET. + +When the defect conditions have disappeared or the defect indication signals are not received anymore, the defect indication signals AIS and RAI should disappear as soon as possible. + +### 5.3.3 Error performance monitoring + +#### 5.3.3.1 General + +Monitoring error performance of the DS and reporting on such performance is optional. + +NOTE – For CRC processing functions within the DS, refer to the options as given in Recommendation I.604. + +#### 5.3.3.2 Error performance parameters + +The ET will receive the following transmission-error information to allow it to evaluate the error performance parameters defined in Recommendation G.821. + +Occurrences of transmission-error events indicate the quality of transmission. The occurrences that shall be detected and reported are: + +- no events; +- CRC error; +- severely-errored framing. + +The occurrences that should be detected and reported are: + +- frame synchronization bit error; +- line code violation; +- controlled slip. + +These are defined in the following subclauses. + +**5.3.3.2.1 CRC error event:** A CRC error event is the occurrence of a received CRC code that is not identical to the corresponding locally-calculated code. + +**5.3.3.2.2 Severely-errored framing event:** A severely-errored framing event is the occurrence of two or more framing-bit errors within a 3 ms period. Contiguous 3 ms intervals shall be examined. The 3 ms period may coincide with the multi-frame defined in Recommendation G.704. + +NOTE – The use of existing 2 of 4, 2 of 5, 3 of 5, etc. framing error detection criteria may be substituted for this criterion. + +**5.3.3.2.3 Frame synchronization bit error event:** A frame synchronization bit error event is the occurrence of a received framing-bit error. + +**5.3.3.2.4 Line code violation event:** A line code violation event is the occurrence of a received violation that is not part of a line code substitution rule. + +**5.3.3.2.5 Controlled slip event:** A controlled slip event is the occurrence of a replication, or deletion, of a frame by the receiving terminal. A controlled slip may occur when there is a difference between the timing of a synchronous receiving terminal and the carrier signal. A controlled slip event is normally associated with the ET and TE layer 1. + +**5.3.4 Status report functions:** Status report functions cover information which relates to the overall operation and performance of the DS. + +Listed below are descriptions of the status report functions: + +- i) Transmission errors + +This information, derived in the DS, allows the ET to evaluate transmission error performance. + +- ii) Loopback 1 status + +This information gives the status of loopback 1. + +- iii) Loopback 1A status + +This information gives the status of loopback 1A. + +- iv) Loopback 2 status + +This information gives the status of loopback 2. + +- v) User network interface power feed status (optional) + +This information indicates the status of the power feed at the user network interface at T reference point. + +- vi) User network interface power feed fault (optional) + +This information indicates a failure of the normal power source. + +- vii) Defect indication information + +This information is transmitted automatically under conditions specified in 5.3.2.1. + +# 6 Operation and maintenance procedures + +## 6.1 General + +This subclause describes the operational and procedural functions associated with access digital sections implementing the CRC processing capabilities described in Annex A/I.604. + +This CRC processing is part of the overall operation and maintenance functionality prescribed for the DS under NT1 options 1, 4 and 2. CRC generation and results reporting occur in the functional groupings ET, NT1 (option 2 only) and TE. + +The following subset of the DS maintenance functions may be assigned to the NT1. + +- Recognition of loss of incoming signal (6.5). +- Recognition of loss of frame alignment (only option 2). +- Generation of AIS (6.5). +- Generation of CRC (option 2 only, see Note 1). +- Monitoring of DL: The NT1 must monitor the received DL (at each of its two interfaces) for messages that require some NT1 action (e.g. loopback) and these messages are not usually passed to the opposite interface. DS passes the DL messages transparently or non-transparently depending on options according to Recommendation I.604. +- Monitoring of CRC: Figures 6, 7 and 8 illustrate this functionality which is consistent with Annex A/I.604, NT1 options 1, 2 and 4, respectively. In NT1 using option 2 or option 4, as an option, the NT1 may monitor the received CRC block from each interface. +- Calculation, storage and thresholding of performance monitoring (PM) data: As an option, the NT1 may calculate layer 1 performance parameters (i.e. CRC check sums and their interpretation) or provide storage for PM-data history, or provide threshold reporting for PM data, or any logical combination of these functions (Note 2). +- Provision of loopback 2 functionality: The NT1 must provide loopback 2 functionality; i.e. activate and release a loopback 2 in response to priority message received via the DL of either interface. + +#### NOTES + +- 1 The NT1 using option 4 must not generate new CRCs and the NT1 using option 2 must generate new CRCs. +- 2 In the NT1 using option 2, layer 1 performance parameters calculated at both sides of NT should be transmitted to both the ET and the TE using LAPD frames (see Figure 8). + +## 6.2 4 kbit/s data link + +The 4 kbit/s data link (DL) is derived from the m-bits of 1544 kbit/s frame overhead. The DL carries two types of information: control signals and performance data. Unless otherwise indicated, the specification of these signals is the same for both directions of transmission. + +The control signals are pre-emptive, i.e. when sent, they overwrite other signals on the DL. The two categories of control signals (priority and command messages) are defined in 6.2.1.1 and 6.2.1.2. + +The performance data is transmitted in a simplified format similar to the Q.921/LAPD protocol and is described in 6.2.2. + +### 6.2.1 Control signals + +Control signals are repetitive bit-oriented codewords used to convey alarm and command information. Control signals preempt all other uses of the DL. + +Control signals consist of multiple repetitions of bit-oriented codewords conforming to the format: + +11111111 0xxxxxx0 (where the leftmost bit is transmitted first.) + +Table 1 defines the specific codewords used for priority messages, e.g. alarms, and for commands, appropriate to the DS. Other bit-oriented codewords may be used on the DL to support operation and maintenance of digital links and of TEs. NT1s and regenerators shall not act upon any bit-oriented codewords other than those listed in Table 1. NT1s/regenerators shall not source any messages other than AIS and priority messages listed in Table 1 and then only under conditions prescribed for their use. + +TABLE 1/G.963 + +#### **Assigned bit-oriented data link messages** + +| Function | Codeword
(Note 1) | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------| +| Priority messages | | +| RAI | 11111111 00000000 | +| Loopback retention | 11111111 01010100 (Note 3) | +| NT1 power off (option 2 only) | 11111111 00111000 | +| Command messages (Note 2) | | +| Loopback 1A activate | 11111111 01001000 | +| Loopback 2 activate | 11111111 01110000 | +| Loopback 2 deactivate | 11111111 00011100 | +| Universal loopback deactivate | 11111111 00100100 | +| NOTES
1 The leftmost bit is transmitted first.
2 The loopbacks are defined in 5.2.1.
3 The codeword “Loopback Operate Acknowledge” (LOA) is the same codeword as “Loopback Retention”. | | + +#### **6.2.1.1 Priority messages** + +Priority messages indicate a service-affecting condition. They shall be transmitted until the condition no longer exists, but not for less than one second. These messages may be interrupted for a maximum of 100 ms per interruption with a minimum interval of one second between the start of interruptions. + +NOTE – The ET is aware that the state “NT1 power off” may appear to the access digital section as a fault state. In NT1 option 2, to distinguish between NT1 power off and the fault state, the DS must transmit NPO to the ET in the “Loss of NT1 power” state (dying gasp). + +#### **6.2.1.2 Command messages** + +Command messages are transmitted to perform loopback functions for the DS. They may also be used to support the DS and TE maintenance functions. Only those messages listed in Table 1 shall be acted on by NT1s/regenerators. Command codewords will be repeated at least 10 times. NT1s/regenerators shall act upon commands (see Recommendation I.604) when the appropriate codewords are detected at least 5 times in 10 intervals. + +### **6.2.2 Performance report message (PRM)** + +Performance verification of the DS is based on facility monitoring and calculation and comparison of check sums generated by framing sources. Framers insert a six-bit check sum into the C1 through C6 bit positions of the 1544 kbit/s frame F-bits overhead. This CRC-6 polynomial is the check sum associated with the preceding multi-frame. + +Partial verification of the performance is possible at any point in the section by securing a 1544 kbit/s frame reference, calculating CRC-6 check sums, and comparing them to those (received in the bit positions reserved for C1 through C6) calculated and inserted by the framer. Upstream performance can thus be verified from the monitoring point for both ET and NT/TE generated information. The downstream performance can be inferred from the performance report described below. + +#### 6.2.2.1 Method of operation + +This subclause illustrates the use of the m-bits for conveying performance information specified in 5.3.3.2. Performance information appearing in one direction of transmission is a quantification of the quality of transmission in the opposite direction. + +A simplified version of the LAPD protocol, utilizing only unnumbered frames, is used for this purpose. Reports are transmitted at one second intervals, and that data for each second is repeated in four messages in subsequent reporting periods. The repetitions provide robustness to the method. The specification of these signals is the same for both directions of transmission. + +NOTE – As mentioned in 6.2, the m-bits are also used for the transmission of priority messages, e.g. alarms and command and response messages. In the DS supporting options 1 and 4 (see Recommendation I.604), such messages have a priority over performance report. In system supporting option 2 of Recommendation I.604, the performance report message including CRC error information can be sent at a maximum of 100 ms per interruption while transmitting RAI. + +Both the received and the transmitted signals include PRMs sent each second. The one-second timing (which defines the measurement interval) may be derived from the transmitted or received signal, as applicable, or from any source with an accuracy of $\pm 32$ ppm, or better. The phase of the one-second periods with respect to the occurrence of error events is arbitrary, i.e. the one-second timing does not depend on the time of occurrence of any error event. + +The message structure is shown in Figure 9 and an example in Figure 10. PRMs are summarized in Tables 3 and 4. + +Counts of events are accumulated in each contiguous one-second interval. At the end of each one-second interval, a modulo 4 counter is incremented, and the appropriate performance bits are set in the $t_0$ octets (octets 5 and 6 in Figure 9). These octets, along with octets that carry the performance bits of the preceding three one-second intervals, form the performance report. + +Complete specifications for generation and application of the performance report message are found in Recommendation I.431. + +###### NOTES + +1 A single PRM occupies 15 bytes. This is transmitted once per second. A PRM with one address should not be blocked or overwritten by one with another address. When the NT1 with CRC processing (option 2 according to Recommendation I.604) transmits three kinds of 15-byte PRMs. The three PRMs occupy 45 bytes per second (see Figure 8). The transmission algorithm for PRMs is given in Appendix I. + +2 In the DS based on option 2, the bits “TEI” and “C/R” of the LAPD frame are used as addresses to indicate the monitored locations (ET to NT1 networkside)/(NT1 networkside to ET)/(NT1 userside to TE)/(TE to NT1 userside) of performance information contained in a message. The C/R bit indicates whether the PRMs source is NT1-networkside source/TE source (C/R = 0) or ET source/NT1-userside source (C/R = 1). The TEI bit indicates whether the monitored section is the link between ET and NT1 (TEI = 0) or the link between NT1 and TE (TEI = 1). + +## 6.3 Partitioning of functions + +Recommendation I.431 defines the network side of the user-network interface at reference point T as one functional block which supports the operation and maintenance procedures across the T reference point and the primitive procedures at the ET layer 1/ET layer 2 boundary and at the ET layer 1/system management boundary. This block includes the functional groupings NT1, LT and ET layer 1. + +This concept is described in terms of a state machine, called the G state machine in Recommendation I.431. + +![](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +| Octet No. | Octet label | | | | | | | | Octet control | | +|-----------|--------------|----|----|----|----|-----|----|----|----------------------|----------------------| +| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | | +| 1 | Opening flag | | | | | | | | 01111110 | | +| 2 | SAPI | | | | | C/R | EA | | 00111000 or 00111010 | | +| 3 | TEI | | | | | | | EA | | 00000001 or 00000011 | +| 4 | Control | | | | | | | | 00000011 | | +| 5 | G3 | LV | G4 | U1 | U2 | G5 | SL | G6 | One-second report | | +| 6 | FE | SE | LB | G1 | R | G2 | Nm | N1 | | | +| 7 | G3 | LV | G4 | U1 | U2 | G5 | SL | G6 | | | +| 8 | FE | SE | LB | G1 | R | G2 | Nm | N1 | | | +| 9 | G3 | LV | G4 | U1 | U2 | G5 | SL | G6 | | | +| 10 | FE | SE | LB | G1 | R | G2 | Nm | N1 | | | +| 11 | G3 | LV | G4 | U1 | U2 | G5 | SL | G6 | | | +| 12 | FE | SE | LB | G1 | R | G2 | Nm | N1 | | | +| 13 | FCS | | | | | | | | Variable | | +| 14 | | | | | | | | | | | +| 15 | Closing flag | | | | | | | | | | + +T1817080-92/d09 + +### Address + +00111000 +00111010 +00000001 +00000011 + +#### Interpretation + +SAPI = 14, C/R = 0 (NT1 – networkside/TE), EA = 0 +SAPI = 14, C/R = 1 (ET/NT1 – userside), EA = 0 +TEI = 0, EA = 1 (Performance report related to the access digital section) (Note 2) +TEI = 1, EA = 1 (Performance report related to the link between NT1 and TE) (Note 3) + +### Control + +00000011 + +#### Interpretation + +Unacknowledged information transfer + +### One-second report + +G1 = 1 +G2 = 1 +G3 = 1 +G4 = 1 +G5 = 1 +G6 = 1 +SE = 1 +FE = 1 +LV = 1 +SL = 1 +LB = 1 +U1, U2, R +NmN1 = 00, 01, 10, 11 + +#### Interpretation + +CRC error event = 1 + $1 < \text{CRC error event} \leq 5$ + $5 < \text{CRC error event} \leq 10$ + $10 < \text{CRC error event} \leq 100$ + $100 < \text{CRC error event} \leq 319$ +CRC error event $\geq 320$ +Severely-errored framing bit $\geq 1$ (FE shall be = 0) +Framing synchronization bit error event $\geq 1$ (SE shall be = 0) +Line code violation event $\geq 1$ +Slip event $\geq 1$ +Loopback 3 activated indication +Reserved for national option (Default value is all "0") +One-second report modulo 4 counter + +### FCS + +Variable + +#### Interpretation + +CRC16 Frame Check Sequence + +###### NOTES + +- 1 The rightmost bit is transmitted first. +- 2 In options 1 and 4 of Recommendation I.604, this report is between the ET and TE. In option 2 of Recommendation I.604, this report is between the ET and NT1. +- 3 This applies only to implementations following option 2 of Recommendation I.604. + +FIGURE 9/G.963 + +### Performance report message structure + +| | $t = t_0$ | $t = t_{0+1}$ | $t = t_{0+2}$ | $t = t_{0+3}$ | +|------------------------------------------------------------------------------------------|-----------|---------------|---------------|---------------| +| FLAG | 01111110 | 01111110 | 01111110 | 01111110 | +| ADDRESS OCTET 1 | 00111000 | 00111000 | 00111000 | 00111000 | +| ADDRESS OCTET 2 | 00000001 | 00000001 | 00000001 | 00000001 | +| CONTROL | 00000011 | 00000011 | 00000011 | 00000011 | +| MESSAGE OCTET 1 | 00000001 | 00000000 | 10000000 | 00100000 | +| MESSAGE OCTET 2 | 00000000 | 00000001 | 00000010 | 00000011 | +| MESSAGE OCTET 3 | 00000000 | 00000001 | 00000000 | 10000000 | +| MESSAGE OCTET 4 | 00010011 | 00000000 | 00000001 | 00000010 | +| MESSAGE OCTET 5 | 00000000 | 00000000 | 00000001 | 00000000 | +| MESSAGE OCTET 6 | 01000010 | 00010011 | 00000000 | 00000001 | +| MESSAGE OCTET 7 | 00000010 | 00000000 | 00000000 | 00000001 | +| MESSAGE OCTET 8 | 00000001 | 01000010 | 00010011 | 00000000 | +| FCS OCTET 1 | xxxxxxx | xxxxxxx | xxxxxxx | xxxxxxx | +| FCS OCTET 2 | xxxxxxx | xxxxxxx | xxxxxxx | xxxxxxx | +| $t = t_{0-3}$ , Slip = 1, all other parameters = 0, $N(t) = 1$ | | | | | +| $t = t_{0-2}$ , Severely errored framing event = 1, all other parameters = 0, $N(t) = 2$ | | | | | +| $t = t_{0-1}$ , CRC error events = 1, all other parameters = 0, $N(t) = 3$ | | | | | +| $t = t_0$ , CRC error events = 320, all other parameters = 0, $N(t) = 0$ | | | | | +| $t = t_{0+1}$ , CRC error events = 0, all other parameters = 0, $N(t) = 1$ | | | | | +| $t = t_{0+2}$ , CRC error events = 6, all other parameters = 0, $N(t) = 2$ | | | | | +| $t = t_{0+3}$ , CRC error events = 40, all other parameters = 0, $N(t) = 3$ | | | | | +| NOTE – This example describes the C/R = 0/TEI = 0 case only. | | | | | + +FIGURE 10/G.963 + +### Performance report messages – Example + +Two state machines are defined to describe the relationship between signals across reference point T (which are indicated as signals (SIGs) in Figure 3 and defined in Recommendation I.431) and signals across reference point V3 (which are indicated as function elements (FEs) in Figure 3 and defined in 6.5) and the relationship between FEs and primitives. One of these state machines is in the DS (DS virtual state machine), and the other is at the network side of the V3 reference point (ET layer 1 virtual state machine). Figure 11 illustrates this approach. + +In addition to primitives defined in Recommendations I.431 and Q.920 related to call control, Figure 11 also introduces a new set of primitives related to configuration control and the control of loopbacks. Partitioning of operation and maintenance procedures between two state machines is used for the convenience of easy and accurate description. The ET layer 1 state machine is to be viewed as virtual and is not intended to imply any particular implementation; however, the functional behaviour shall be as defined in the ET state tables (see Table A.1). This is required to interwork with the DS state machine defined in this Recommendation and to satisfy the requirements specified in the G state table in Recommendation I.431. + +However, in order to implement a customer access, the virtual DS state machine has to be partitioned further. Figure 12 shows the partitioning of the DS state machine into NT1 state machine (NT-states) and LT state machine (LT-states). + +The NT1 state machine supports user-network interface procedures in accordance with Recommendation I.431 based on signals, and interacts with the LT state machine by means of a signal repertoire (SIGs) which must be supported by the line transmission system. The LT state machine interacts with the ET layer 1 state machine by means of a set of function elements (FEs). The ET layer 1 state machine contains those states which represent the local exchange view of the status of the interface at reference point T and of DS. It supports the already specified primitive procedures to provide services to ET layer 2 and system management in accordance with Recommendation I.431, and additional primitive procedures for the support of functions associated with DS. + +Figure 12 provides information for the description of the 1544 kbit/s primary rate access digital transmission system defined in Figure 1. + +## 6.4 Definitions of signals at the T reference point + +Signals exchanged between the DS and TE via the interface at reference point T under normal and defect conditions are defined in Recommendation I.431. + +## 6.5 Definition of FEs at the V3 reference point + +The function elements represent input signals which are consumed if a state transition occurs, even if it is a null transition (remains in the same state), and are no longer available to initiate one more state transition. + +![Diagram of state machines showing the DS state machine, ET layer 1 state machine, ET layer 2, and System management components.](90ddf538ef276510e2b631f7b96654e6_img.jpg) + +The diagram illustrates the interaction between several state machines in a digital transmission system. On the left, a vertical line represents the 'Access digital section'. At the top of this line is reference point 'T' with 'Signals' entering from the left. The line connects to a box labeled 'DS state machine'. From the right side of this box, the line continues to reference point 'V3', where 'FEs' (Function Elements) are indicated. The line then connects to a large box labeled 'ET layer 1 state machine (ET states)'. From the right side of this box, three arrows point to other components: + + +- An arrow labeled 'I.431' points to a box labeled 'ET layer 2'. +- An arrow labeled 'I.431' points to a box labeled 'related to call control'. +- An arrow labeled 'additional' points to a box labeled 'related to configuration control'. +- Another arrow labeled 'additional' points to a box labeled 'related to loopback control'. + + The boxes 'related to call control', 'related to configuration control', and 'related to loopback control' are grouped together by a large curly brace on their right side, labeled 'System management'. At the bottom right of the diagram is the text 'T1814850-92/d10'. + +Diagram of state machines showing the DS state machine, ET layer 1 state machine, ET layer 2, and System management components. + +FIGURE 11/G.963 +State machines + +![Diagram illustrating the partitioning of the DS state machine. The diagram shows three main state machines: NT1 state machine (NT states), LT state machine (LT states), and ET layer 1 state machine (ET states). The NT1 state machine is connected to external signals and the LT state machine via SIGs. The LT state machine is connected to the ET layer 1 state machine via function elements. The ET layer 1 state machine is connected to ET layer 2 and to the Operation control procedure (part of System management) via MPH-AI, MPH-DI, MPH-L..., and MPH-EI. A 'Virtual DS state machine (DS states)' is shown at the bottom, connected to T and V3. A 'Access digital section' is indicated between the NT1 state machine and the function elements. Reference T1817090-92/d11 is present.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +Diagram illustrating the partitioning of the DS state machine. The diagram shows three main state machines: NT1 state machine (NT states), LT state machine (LT states), and ET layer 1 state machine (ET states). The NT1 state machine is connected to external signals and the LT state machine via SIGs. The LT state machine is connected to the ET layer 1 state machine via function elements. The ET layer 1 state machine is connected to ET layer 2 and to the Operation control procedure (part of System management) via MPH-AI, MPH-DI, MPH-L..., and MPH-EI. A 'Virtual DS state machine (DS states)' is shown at the bottom, connected to T and V3. A 'Access digital section' is indicated between the NT1 state machine and the function elements. Reference T1817090-92/d11 is present. + +FIGURE 12/G.963 +**Partitioning of the DS state machine** + +The following repertoire of function elements associated with the operation and maintenance procedures is defined by the coding given in Table 2: + +- FE A (LT <-- ET) indication of operational frames to DS +- FE B (LT --> ET) indication of operational frames from DS +- FE C (LT --> ET) indication of RAI from DS +- FE D (LT <-- ET) indication of RAI to DS +- FE E (LT --> ET) indication of LOS from DS +- FE F (LT <-- ET) indication of LOS to DS +- FE G (LT --> ET) indication of AIS from DS +- FE H (LT --> ET) indication of CRC error information from TE/NT2 +- FE I (LT <-- ET) indication of CRC error information to DS +- FE J (LT <-- ET) request for loopback 2 activate +- FE K (LT <-- ET) request for loopback 1 activate + +- FE L(LT <-- ET) request for loopback 1A activate +- FE N (LT --> ET) loopback operate acknowledge +- FE O (LT <-- ET) request for loopback deactivate +- FE R (LT <-- ET) request for loopback 2 deactivate +- FE S (LT -->ET) indication of NT1 power off (optional) +- FE T (LT -->ET) indication of CRC error information from NT1-networkside (option 2 only) +- FE U (LT --> ET) indication of CRC error information from NT1-userside (option 2 only) +- FE X (LT <-- ET) indication of AIS to DS + +Tables 3 and 4 illustrate PRMs associated with the ET, NT1 or TE and transmitted through the DS. + +TABLE 2/G.963 + +### **Signals between ET and DS at reference point V3 under normal and abnormal conditions** + +| Name | Conditions | FE | +|-----------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| NOF
(Normal operational frame) | Operational frame with:
– active associated CRC bits;
– no defect indication;
– PRMs transmitted and other m-bits available (tables 3 and 4). | FE A, FE B | +| RAI | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of eight binary ONEs and eight binary ZEROs (11111111 00000000) in the m-bits;
– PRMs transmitted during the maximum of 100 ms interval (option 2 only). | FE C, FE D | +| LOS | No received incoming signal (Loss of signal). | FE E, FE F | +| AIS | Continuous stream of binary ONEs (Recommendation M.20). | FE G, FE X | +| RLIA | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of 11111111 01001000 in the m-bits for request for loopback 1A activate. | FE L | +| RL2 | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of 11111111 01110000 in the m-bits for request for loopback 2 activate. | FE J | +| L2D | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of 11111111 00011100 in the m-bits for request for loopback 2 deactivate. | FE R | +| LD | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of 11111111 00100100 in the m-bits for request for loopback deactivate. | FE O | +| LOA | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of 11111111 01010100 in the m-bits for loopback operate acknowledge. | FE N | +| NPO
(Optional) | Operational frame with:
– active associated CRC bits;
– 16-bit sequence of 11111111 00111000 in the m-bits for indication of NT1 power off. | FE S | + +TABLE 3/G.963 + +### **Definition of performance report messages (Options 1 and 4 NT1)** + +| Name | Information | TEI | C/R | FEs | +|-------------------|-------------------------------------------------|-----|-----|------| +| PRM ET | Includes performance information detected at ET | 0 | 1 | FE I | +| PRM TE | Includes performance information detected at TE | 0 | 0 | FE H | + +TABLE 4/G.963 + +### **Definition of performance report messages (Option 2 NT1)** + +| Name | Information | TEI | C/R | FEs | +|------------------------|---------------------------------------------------------------------|-----|-----|------| +| PRM network | Includes performance information detected at the networkside of NT1 | 0 | 0 | FE T | +| PRM ET | Includes performance information detected at ET | 0 | 1 | FE I | +| PRM TE | Includes performance information detected at TE | 1 | 0 | FE H | +| PRM user | Includes performance information detected at the userside of NT1 | 1 | 1 | FE U | + +## **6.6 PH and MPH primitives** + +### **6.6.1 The repertoire of PH and MPH primitives within ET for the support of functions specified in Recommendations Q.920 and Q.921 for call control** + +The repertoire of these primitives is defined in Recommendations I.431 and Q.921. + +### **6.6.2 Repertoire of MPH primitives within ET for the support of functions associated with the digital section** + +The following primitives should be used between layers 1 and 2 (primitives PH) or between layer 1 and the management entity (primitives MPH). + +| | | +|---------|---------------------------------------------------------------------------------| +| PH-AI | PH Activate indication | +| PH-DI | PH Deactivate indication | +| MPH-AI | MPH Activate indication (used as error recovery and initialization information) | +| MPH-EIn | MPH Error indication with parameter "n" | +| n | Parameter which defines the failure condition relevant to the reported error | + +## **6.7 Digital section (DS) state machine** + +The DS state machine specifies the relationship between signals at reference point T and FEs at reference point V3 under failure conditions and during loopback procedures. + +The state transition table specifies the procedures. It includes the actions to be taken on various events while in a specific state. + +### 6.7.1 DS state definitions + +Hereafter are defined the states that the DS may enter as a result of: signals received across the interface at the T reference point; FEs received across the interface at reference point V3; or internal events. + +The DS states are classified into the following six groups: + +| | | +|--------------|-------------------------------------------------------------------------| +| STATE DS 0.x | NT1 power on/off. In these states LT power is on; | +| STATE DS 1.x | LT power on/off. In these states NT1 power is on; | +| STATE DS 2.x | DS is operational and detects failure conditions at reference point T; | +| STATE DS 3.x | internal DS failure exists; | +| STATE DS 4.x | DS is operational and detects failure conditions at reference point V3; | +| STATE DS 5.x | loopback procedures. | + +#### DS 0.1 state: NT1 power off + +- In general, the DS can neither transmit nor receive signals at reference point T. + +#### DS 0.2 state: NT1 power on + +- This is a transient state, and the DS may change state after detection of the signal received. + +#### DS 1.1 state: LT power off + +- In general, the DS can neither transmit nor receive signals at reference point V3. + +#### DS 1.2 state: LT power on + +- This is a transient state and DS may change state after detection of the signal received. + +#### DS 2.1 state: Operational condition + +- Network timing and layer 1 link are available. +- The DS transmits and receives normal operational frames. + +#### DS 2.2 state: Fault condition No. 2 (FC2) + +- Network timing is not available at reference point T. +- The DS receives RAI (see Recommendation I.431) from reference point T and normal operational frames (NOF) (see Table 2) from reference point V3. +- The DS transmits normal operational frames (see Recommendation I.431) to reference point T and RAI (see Table 2) to reference point V3. + +#### DS 2.3 state: Fault condition No. 4 (FC4) + +- Network timing is available at reference point T. +- The DS recognizes “Loss of signal (LOS)” or “Loss of frame alignment (LFA)” at reference point T and receives RAI from reference point V3 (Recommendation I.431). +- The DS transmits RAI to reference point T and AIS (see Table 2) to reference point V3. + +#### **DS 3.1 state: Fault condition No. 1 (FC1)** + +- Network timing is available at reference point T. +- The DS receives normal operational frames from reference point T and RAI from reference point V3. +- The DS transmits RAI to reference point T and no signal to reference point V3. + +#### **DS 3.2 state: Fault condition No. 3 (FC3)** + +- Network timing is not available at reference point T. +- The DS receives RAI from reference point T and NOF from reference point V3. +- The DS transmits AIS (see Recommendation I.431) to reference point T and RAI to reference point V3. + +#### **DS 3.3 state: Fault condition No. 1 and fault condition No. 3 (FC1 and FC3)** + +- Network timing is not available at reference point T. +- The DS transmits AIS to reference point T and no signal to reference point V3. + +#### **DS 4.1 state: AIS from ET** + +- The DS transmits AIS to reference point T and RAI to reference point V3. + +#### **DS 4.2 state: RAI from ET** + +- The DS transmits RAI to reference point T and NOF to reference point V3. + +#### **DS 5.1 state: Loopback 1A activated** + +- The DS receives at least 10 repetitions of RL1A (see Table 2) followed by loopback retention from the ET. +- The DS operates loopback 1A. +- The DS transmits AIS to reference point T, and LOA (see Table 2) to reference point V3. + +#### **DS 5.2 state: Loopback 2 activated** + +- The DS receives at least 10 repetitions of RL2 (see Table 2) followed by loopback retention from the ET (see Note). +- The DS operates loopback 2. +- The DS transmits AIS to reference point T, and LOA to reference point V3. + +NOTE – In another procedure, NT1 may receive continuous RL2 from the ET. + +### **6.7.2 DS state transition matrix** + +Table 5 provides the DS state transition matrix for 1544 kbit/s primary rate. The indication of DS failure to the ET should have priority over the indication of user-network interface failure to the ET, and the indication of an upstream failure to the ET should have priority over the indication of a downstream failure to the ET. + +The signal specifications and state tables for the user and network sides of reference point T are contained in Recommendation I.431. + +## **6.8 Definition of ET layer 1 state machine** + +The definition of the ET layer 1 state machine is outside the scope of this Recommendation, but because it is important for the understanding of the behaviour of the DS, information on this issue is given in A.2.6. + +TABLE 5/G.963 + +### DS state transition matrix + +| State | | DS0.1 | DS0.2 | DS1.1 | DS1.2 | DS2.1 | DS2.2 | DS2.3 | DS3.1 | DS3.2 | DS3.3 | DS4.1 | DS4.2 | DS5.1 | DS5.2 | +|--------------------------------------------|-------------------------------------------------------------------|---------------|---------------|--------------|---------------|---------------|---------------|-------|---------------|-----------------|---------------|---------------|---------------|-----------------------|----------------------| +| Operational condition or Failure condition | | NT1 power off | NT1 power on | LT power off | LT power on | Operational | FC2 | FC4 | FC1 | FC3 without FC1 | FC3 with FC1 | AIS at V3 | RAI at V3 | Loopback 1A activated | Loopback 2 activated | +| Signal transmitted toward V3 (FEs) | | FE E (Note 3) | FE E | FE E | FE E | FE B | FE C (Note 2) | FE G | FE E (Note 1) | FE C (Note 2) | FE E (Note 1) | FE C (Note 2) | FE B | FE N | FE N | +| Signal transmitted toward T (signals) | | No signal | No signal | AIS | AIS | NOF | NOF | RAI | RAI | AIS | AIS | AIS | RAI | AIS | AIS | +| At T | Reception of NOF from TE | / | / | / | / | – | DS2.1 | DS2.1 | – | / | / | / | – | / | / | +| | Reception of RAI from TE | / | FE C (Note 2) | – | FE C (Note 2) | FE C (Note 2) | – | / | – | – | – | – | FE C (Note 2) | – | – | +| | Loss of incoming signal (LOS)/ Loss of frame alignment (LAF) at T | / | DS2.3 | – | DS2.3 | DS2.3 | DS2.3 | – | – | DS2.3 | – | – | DS2.3 | – | – | +| I
N
T
E
R
N
A
L | No internal network failure | / | – | / | – | – | – | – | DS2.1 | DS2.1 | DS2.1 | – | – | / | / | +| | FC1 | / | DS3.1 | / | DS3.1 | DS3.1 | DS3.1 | DS3.1 | – | DS3.3 | – | DS3.1 | DS3.1 | DS3.1 | DS3.1 | +| | FC3 | / | DS3.2 | / | DS3.2 | DS3.2 | DS3.2 | DS3.2 | DS3.3 | – | – | DS3.2 | DS3.2 | DS3.2 | DS3.2 | +| | Loss of NT1 power | / | DS0.1 | / | DS0.1 | DS0.1 | DS0.1 | DS0.1 | – | DS0.1 | – | DS0.1 | DS0.1 | – | DS0.1 | +| | Return of NT1 power | DS0.2 | / | / | / | / | / | / | / | / | / | / | / | – | / | +| | Loss of LT power | – | DS1.1 | / | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | DS1.1 | +| | Return of LT power | – | DS1.2 | DS1.2 | / | / | / | / | / | / | / | / | / | / | / | +| At V3 | FE A | / | / | / | / | – | – | / | / | – | / | DS2.1 | DS2.1 | DS2.1 | DS2.1 | +| | FE X | / | DS4.1 | – | DS4.1 | DS4.1 | DS4.1 | DS4.1 | DS4.1 | – | – | – | DS4.1 | DS4.1 | DS4.1 | +| | FE D | / | DS4.2 | / | DS4.2 | DS4.2 | – | – | – | – | – | DS4.2 | – | – | – | +| | FE L | / | DS5.1 | / | DS5.1 | DS5.1 | DS5.1 | DS5.1 | DS5.1 | – | – | / | DS5.1 | / | / | +| | FE J | / | DS5.2 | / | DS5.2 | DS5.2 | DS5.2 | DS5.2 | DS5.2 | – | – | / | / | / | / | +| | FE R | / | / | / | / | / | / | / | / | / | / | / | / | / | DS2.1 | +| | FE O | / | / | / | / | / | / | / | / | / | / | / | / | DS2.1 | / | + +### Fault conditions + +– No state change + +/ Impossible situation + +FE x + +DS y Issue function element x + +Go to state DS y + +#### NOTES + +1 When the DS provides AIS rather than LOS, the ET cannot distinguish between FC1 and FC4. + +2 In options 1 and 4, the performance report message cannot be sent from the DS while transmitting RAI. FC2 and FC3 faults are indicated identically at reference point V3. Option 2 allows performance report messages including CRC error information to be sent while transmitting RAI, to localize faults FC2 and FC3 at the ET. + +3 As an option, the DS may transmit FE S followed by FE E to the ET. + +# **Annex A** (to Recommendation G.963) + +## **System management requirements** + +(This annex forms an integral part of this Recommendation) + +## **A.1 Introduction** + +This Recommendation specifies the required functions of the 1544 kbit/s primary rate access digital section and the ET layer 1. In order to ensure correct operation, it is necessary to take into account the assumptions made about the management functions involved. It is assumed that the structure of the management is as given in Recommendation Q.940. + +In this Recommendation, distinction is only made between ET layer 1 and system management. Where the term "system management" is used it corresponds to both system management and layer management as defined in Recommendation Q.940. + +## **A.2 System management requirements** + +### **A.2.1 General** + +System management shall not initiate more than one action at a time to ET layer 1. An action is delimited by the primitive which is issued by system management and the corresponding primitive which confirms completion of the task. + +### **A.2.2 Error indications** + +The management entity takes account of the sequence of primitives before and after the reception of MPH-EI. From the sequence of the primitives, system management may determine the cause of the MPH-EI primitive (e.g. loss of synchronization or loss of signal at the interface at reference point T). + +Upon the occurrence of an error, ET layer 1 shall notify the event to system management by means of the primitive MPH-EI. System management must decide which appropriate actions should be taken (e.g. hold or abandon call). + +### **A.2.3 Loopback operations** + +System management should take into account that when ET layer 1 is in loopback operation it does not send any primitives to ET layer 2. If a primitive is sent by ET layer 2 to ET layer 1 during loopback operation, it will be ignored by ET layer 1. + +The setting of loopback is initiated by system management by issuing a primitive MPH-LxAR, where x indicates the type of loopback (2, 1 or 1A). + +The setting of loopbacks 2, 1 and 1A is confirmed to system management by means of the loopback acknowledge primitive. System management should be able to interpret this loopback acknowledge as a loopback confirmation. + +### **A.2.4 Information to be sent in the D-channel during loopback operation** + +The information sent in the D-channel should not imitate any HDLC pattern. However, it is the responsibility of system management to decide to send the required pattern for fault localization. + +### **A.2.5 Configuration control** + +System management shall ensure that any action related to configuration control will be issued only while the access is not active with user traffic. + +### **A.2.6 ET state machine** + +#### **A.2.6.1 ET state definitions** + +Hereafter are defined the states that ET layer 1 may enter as a result of: function elements (FEs) received across reference point V3; service primitives received (PH-, MPH-primitive); or internal events. + +##### **ET0.1 state: Loss of power state** + +- In this state the ET can neither transmit nor receive signals. + +##### **ET1.1 state: Operational state** + +- Layer 1 link is available. +- The ET receives normal operational frames (NOF) (see Table 2). +- The ET transmits NOF to reference point V3. +- The ET checks the received frame for CRC and other errors and generates a PRM to reference point V3. + +##### **ET2.1 state: Fault condition No. 1 (FC1: see Recommendation I.431)** + +- The ET detects loss of incoming signal. +- The ET transmits RAI (see Table 2) to reference point V3. + +##### **ET2.2 state: Fault condition No. 2 or No. 3 (FC2 or FC3)** + +- The ET receives RAI (see Note). +- The ET transmits NOF to reference point V3. +- The ET checks the received frame for CRC and other errors and generates a PRM to reference point V3. + +##### **ET2.3 state: Fault condition No.4 (FC4)** + +- The ET detects AIS. +- The ET transmits RAI to reference point V3. + +##### **ET2.4 state: Power on state** + +- This is not a stable state, the ET cannot remain in it. +- No signal is transmitted to reference point V3. +- The ET must change state after identification of a received signal or recognition that no signal is being received (loss of signal, loss of frame alignment event). + +NOTE – The DS supporting NT1 option 2 allows transmission of performance report messages including CRC error information to both interfaces while transmitting RAI (see Appendix I). The ET can localize a failure to either: + +- i) the T reference point (FC2). If frames with performance report messages from TE including continuous CRC error information (defined in Recommendation I.431) are received; or +- ii) within the access digital section (FC3), if frames with performance report messages from the NT1 network side including continuous CRC error information are received. + +In options 1 and 4, the performance report message cannot be sent while transmitting RAI. FC2 and FC3 faults are indicated identically at reference point V3. + +#### A.2.6.2 ET state matrix + +The state transition table specifies the procedures. It includes the action to be taken on various events while in a specific state. It specifies the interactions with ET layer 2 and system management which are required to support the layer interface procedures in accordance with Recommendation I.431 (sequences of PH- and MPH-primitives in compliance with I.431) and the interactions across the layer interface between ET layer 1 and system management for the support of functions within the DS. + +The ET state matrix is given in Table A.1. + +TABLE A.1/G.963 + +##### ET state transmission matrix + +| | State | ET0.1 | ET1.1 | ET2.1 | ET2.2 | ET2.3 | ET2.4 | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------|-----------------|--------------------------------|--------------------------|----------------------------|--------------------------|------------------| +| Definition of the states | Operational condition of the reference point V3 | Power off at ET | Operational | FC1 | FC2/FC3 | FC4 | Power on at ET | +| | Signal toward the reference point V3 | FE F | FE A | FE D | FE A (see Note in A.2.6.1) | FE D | FE F | +| New received event | Loss of ET power | – | PH-DI
MPH-EI0
ET0.1 | MPH-EI0
ET0.1 | MPH-EI0
ET0.1 | MPH-EI0
ET0.1 | MPH-EI0
ET0.1 | +| | Return of ET power | ET2.4 | / | / | / | / | / | +| | FE B | / | – | PH-AI
MPH-AI
ET1.1 | PH-AI
MPH-AI
ET1.1 | PH-AI
MPH-AI
ET1.1 | / | +| | FE C | / | PH-DI
MPH-EI1,
2/3 ET2.2 | MPH-EI2/3
ET2.2 | – | MPH-EI2/3
ET2.2 | ET2.2 | +| | FE E | / | PH-DI
MPH-EI1
ET2.1 | – | MPH-EI1
ET2.1 | MPH-EI1
ET2.1 | ET2.1 | +| | FE G | / | PH-DI
MPH-EI4
ET2.3 | MPH-EI4
ET2.3 | MPH-EI4
ET2.3 | – | ET2.3 | +| Fault conditions | | | | | | | | +| – | No state change | | | | | | | +| / | Impossible situation | | | | | | | +| PH-AI | Physical layer activate indication | | | | | | | +| PH-DI | Physical layer deactivate indication | | | | | | | +| MPH-AI | Management physical layer activate indication | | | | | | | +| MPH-EIn | Management physical layer error indication | | | | | | | +| n = 0 | Power off | | | | | | | +| n = 1 | FC1 fault indication | | | | | | | +| n = 2/3 | FC2/FC3 fault indication | | | | | | | +| n = 4 | FC4 fault indication | | | | | | | +| NOTE – The PH and MPH primitives are discussed in Recommendations Q.921 and I.431. PH-AR primitive is not shown since the interface is not subject to a deactivation procedure. | | | | | | | | + +# **Appendix I** (to Recommendation G.963) + +## **Transmission algorithm of performance report messages at NT1 based on option 2** + +(This appendix does not form an integral part of this Recommendation) + +The equipment supporting option 2 (ET, NT1, TE, ...) transmits PRMs to the interfaces at the beginning of any one-second interval (see Figure 8). + +Each end of the links between ET and NT1 and between NT1 and TE, determine 1 second intervals counting 8000 frames. An NT1 based on option 2 counts the transmission performance events of the received signals from ET and TE within a one-second interval ( $T_n$ ). For that interval ( $T_n$ ), NT1 calculates the performance parameters of each side and inserts them into each LAPD frame. + +At the beginning of interval $T_{n+1}$ , $PRM_{network}$ is transmitted first followed by $PRM_{user}$ . $PRM_{network}$ is transmitted from both sides at the same time, and likewise for $PRM_{user}$ . + +If NT1 receives $PRM_{TE}$ from TE it transmits $PRM_{TE}$ to ET after transmitting $PRM_{network}$ and $PRM_{user}$ at the beginning of the next interval. 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telecommunications. To the right of the globe, the text "International Telecommunication Union" is written in a blue, sans-serif font. + +ITU logo + +International +Telecommunication +Union + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9710 + +# Multi-gigabit fast access to subscriber terminals (MGfast) – Power spectral density specification + +## Summary + +Recommendation ITU-T G.9710 specifies power spectral density (PSD) mask requirements for multi-gigabit fast access to subscriber terminals (MGfast), a set of tools to support reduction of the transmit PSD mask, and a methodology for transmit PSD verification. It supports operation over both twisted pair and coaxial cable media. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.9710 | 2020-02-07 | 15 | 11.1002/1000/14022 | + +## Keywords + +PSD, MGfast. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2020 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Transmit PSD mask ..... | 3 | +| 6.1 Overview ..... | 3 | +| 6.2 Limit PSD mask (LPM)..... | 3 | +| 6.3 Subcarrier masking..... | 4 | +| 6.4 Power spectral density shaping ..... | 4 | +| 6.5 Notching of specific frequency bands ..... | 4 | +| 6.6 Low frequency edge stop-band masking..... | 6 | +| 7 Specification of spectral content..... | 7 | +| 7.1 PSD type ..... | 7 | +| 7.2 PSD mask specifications ..... | 7 | +| 8 Transmit PSD verification ..... | 10 | +| Annex A to Annex O ..... | 12 | +| Annex P – Adaptation to the twisted pair medium ..... | 13 | +| P.1 Termination impedance ..... | 13 | +| Annex Q – Adaptation to the coaxial cable medium ..... | 14 | +| Q.1 Termination impedance ..... | 14 | +| Q.2 Transmit PSD verification ..... | 14 | +| Appendix I – International amateur radio bands ..... | 15 | +| Appendix II – Other aeronautical communication, radio navigation and broadcasting services ..... | 16 | +| Appendix III – Definition of transmitter PSD (TXPSD) for non-continuous transmissions... | 17 | + + + +## Recommendation ITU-T G.9710 + +## Multi-gigabit fast access to subscriber terminals (MGfast) – Power spectral density specification + +# 1 Scope + +This Recommendation specifies the power spectral density for multi-gigabit fast access to subscriber terminals (MGfast), which supports transmission at an aggregate net data rate (the sum of upstream and downstream rates) up to approximately 10 Gbit/s on metallic wires, including twisted pairs and coaxial cables. The adaptations to these two media are specified in Annexes P and Q respectively. In this edition of the Recommendation, only one peer MTU-R/NT is connected to the MTU at the optical network unit (MTU-O); multiple MTU-R/NTs connecting to a single MTU-O is out of scope of this edition of the Recommendation. MGfast spectral usage complies with the 424 MHz and 848 MHz PSD types, while in this edition of the Recommendation only the 424 MHz power spectral density (PSD) type is specified. + +It specifies: + +- power spectral density (PSD) limit mask requirements; +- a set of tools to support reduction of the transmit PSD mask; and +- a methodology and termination impedance requirements for transmit PSD verification. + +This ensures that the technology can address: + +- regional requirements; +- operator deployment requirements, for example, compatibility with other digital subscriber line (DSL) technologies; +- applicable electromagnetic compatibility (EMC) regulations or standards; and +- local EMC issues. + +Conformance of equipment with this ITU-T Recommendation may not ensure compliance with specific national or regional regulations on electromagnetic compatibility when installations are taken into service. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +[ITU-T G.993.2] Recommendation ITU-T G.993.2 (2019), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. + +[ITU-T G.997.2] Recommendation ITU-T 997.2 (2019), *Physical layer management for G.fast transceivers*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 ceiling(*x*):** The smallest integer which is not less than *x*. + +**3.2.2 floor(*x*):** The largest integer which is not greater than *x*. + +**3.2.3 *fsc*:** A parameter representing the frequency of subcarrier spacing. + +**3.2.4 subcarrier:** A fundamental element of a discrete multitone (DMT) modulator. The modulator partitions the channel bandwidth into a set of parallel subchannels. The centre frequency of each subchannel is a subcarrier onto which bits may be modulated for transmission over a channel. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------|-----------------------------------------------------------| +| DAB | Digital Audio Broadcasting | +| DMT | Discrete Multitone | +| EMC | Electromagnetic Compatibility | +| ESD | Energy Spectral Density | +| FDS | Full duplex compatible Downstream Sub-frame | +| FDX | Full Duplex | +| FM | Frequency Modulation | +| FUS | Full duplex compatible Upstream Sub-frame | +| IAR | International Amateur Radio | +| LESM | Low-frequency Edge Stop-band Mask | +| LPM | Limit PSD Mask | +| MGfast | Multi-gigabit Fast Access to Subscriber Terminals | +| MIB | Management Information Base | +| MTU | MGfast Transceiver Unit | +| MTU-O | MTU at the Optical Network Unit | +| MTU-R | MTU at the Remote Site (i.e., subscriber end of the loop) | +| NM | Notching Mask | +| PSD | Power Spectral Density | +| PSM | PSD Shaping Mask | +| RFI | Radio Frequency Interference | +| SM | Subcarrier Mask | +| TDD | Time-Division Duplexing | +| TxPSDM | Transmit PSD Mask | + +VHF Very High Frequency + +# 5 Conventions + +None. + +# 6 Transmit PSD mask + +## 6.1 Overview + +The transmit PSD mask (TxPSDM) is constructed from the combination of the following masks: + +- limit PSD mask (LPM); +- subcarrier mask (SM); +- PSD shaping mask (PSM); +- notching mask (NM); and +- low-frequency edge stop-band mask (LESM). + +The TxPSDM applied to the MGfast transceiver unit (MTU) at the optical network unit (MTU-O) or at the MTU remote site (i.e., subscriber end of the loop) (MTU-R) may be different. + +For an MTU, the PSD of the transmit signal at any frequency shall never exceed the TxPSDM. + +The LPM (see clause 7.2.1) specifies the absolute maximum limit of the TxPSDM. The subcarrier mask (SM), PSD shaping mask (PSM), notching mask (NM) and low-frequency edge stop-band mask (LESM) provide reduction of the TxPSDM using the following mechanism: + +- subcarrier masking; +- notching of specific frequency bands; +- PSD shaping; and +- low-frequency edge stop-band masking. + +Support of these mechanisms is mandatory in both the MTU-O and the MTU-R. + +The TxPSDM shall comply with applicable national and regional regulatory requirements. + +NOTE 1 – When determining the correct PSD to use in a particular jurisdiction, operators should use tools provided to ensure compliance with national and regional electromagnetic compatibility (EMC) regulations giving special consideration to protecting receivers for the safety of life services which may not be immediately adjacent to the drop wires carrying MGfast signals. Examples include various very high frequency (VHF) aeronautical radio navigation channels in the band 108-117.975 MHz, smart grid utility management systems channels in the band 450-470 MHz, and aeronautical emergency communications channels (e.g., 121.5 MHz, 406 MHz) and maritime emergency communications channels in the HF and VHF bands. + +NOTE 2 – TXPSDM is defined in various averaging bandwidths according to frequency as defined in Table 8-1, except in sub-bands at the low frequency band edge and in the region of management information base (MIB) defined notches, where TXPSDM\_W (1 MHz wideband) and TXPSDM\_N (10 kHz narrowband) masks apply as described in clauses 6.5 and 6.6. + +NOTE 3 – In point-to-multipoint operation, multiple MTU-Rs are connected to one MTU-O. In this mode of operation, the MTU-O controls transmission levels of upstream signals of each individual MTU-R to ensure compliance to the TxPSDM during upstream transmission. + +## 6.2 Limit PSD mask (LPM) + +The limit PSD mask (LPM) defines the absolute maximum PSD limit of the TxPSDM that shall never be exceeded. All the other mask definitions and mechanisms used to construct the TxPSDM can only result in a reduction of the mask from the limits established by the LPM. + +## 6.3 Subcarrier masking + +Subcarrier masking shall be used to eliminate transmission on one or more subcarriers. The subcarrier mask (SM) is configured in the distribution point management information base (DP-MIB) by use of the ITU-T G.997.2 parameter CARMASK. The transmit power of subcarriers specified in the SM shall be set to zero (linear scale). The SM shall override all other instructions related to the transmit power of the subcarrier. + +The SM is defined as a number of masked frequency bands. Each band is specified by a start subcarrier index ( $x_L$ ) and a stop subcarrier index ( $x_H$ ), as $\{x_L, x_H\}$ . An SM including $S$ bands can be represented in the following format: + +$$SM(S) = [\{x_{L1}, x_{H1}\}, \{x_{L2}, x_{H2}\}, \dots, \{x_{LS}, x_{HS}\}]$$ + +All subcarriers within the band, i.e., with indices higher than or equal to $x_L$ and lower than or equal to $x_H$ , shall be switched off (transmitted with zero power). + +NOTE – The SM is intended to incorporate both masked subcarriers that are defined by an annex defining regional requirements so as to comply with local regulations and masked subcarriers that are defined by the user or service provider to facilitate local deployment practices. Protection of radio services is not intended to be addressed by subcarrier masking; it is addressed by notching (see clause 6.5). + +## 6.4 Power spectral density shaping + +Power spectral density (PSD) shaping allows reduction of the TxPSDM in some parts of the spectrum, mainly for spectrum compatibility and coexistence with other access and home network technologies. The PSD shaping mask (PSM) is configured in the DP-MIB by use of the ITU-T G.997.2 parameter PSDMASK. + +The PSM is defined on the frequency range between the lowest subcarrier $x_1$ (with $x_1 = \text{ceiling}(f_{tr1}/f_{sc})$ ) and the highest subcarrier $x_H$ (with $x_H = \text{floor}(f_{tr2}/f_{sc})$ ), and consists of one or more frequency segments. The boundaries of the segments are defined by set breakpoints. Within each segment, the PSM may either be constant or form a linear slope between the given breakpoints (in dBm/Hz) with the frequency expressed in a linear scale. + +Each breakpoint of the PSM is specified by a subcarrier index $x_n$ and a value of $PSD_n$ at that subcarrier expressed in dBm/Hz, $\{x_n, PSD_n\}$ . $PSD_1$ shall also apply to subcarriers below $x_1$ , and $PSD_H$ shall also apply to subcarriers above $x_H$ . A PSM including $S$ segments can be represented by $(S+1)$ breakpoints in the following format: + +$$PSM(S) = [\{x_1, PSD_1\}, \{x_2, PSD_2\}, \dots, \{x_S, PSD_S\}, \{x_H, PSD_H\}]$$ + +An MTU shall support configuration of at least 32 PSM breakpoints. + +If one or more PSM breakpoints are set above the LPM, the transmit PSD mask shall be set to: $TxPSDM = \min(PSM, LPM)$ . All values of $PSD_n$ of PSM breakpoints shall be set above $-90$ dBm/Hz. + +## 6.5 Notching of specific frequency bands + +The MTU shall be capable of being configured to notch one or more specific frequency bands in order to protect radio services; for example, amateur radio bands or broadcast radio bands. The international amateur radio (IAR) bands to be notched are referred to as IAR bands, whilst the rest of the bands to be notched are referred to as radio frequency interference (RFI) bands. + +For RFI bands, each notch in the notching mask (NM) shall be defined in terms of subcarrier indices $SC_{start}$ and $SC_{stop}$ . + +The valid range of notch start tone index, $SC_{start}$ , is all valid tone indices that are less than or equal to the minimum frequency of the protected radio band minus $f_{sc}/2$ . The valid range of notch stop + +tone index, $SC_{stop}$ , is all valid tone indices that are higher than or equal to the maximum frequency of the protected radio band plus $f_{sc}/2$ . + +An MTU shall support notching of 32 RFI bands simultaneously. + +In addition, an MTU shall support notching of 15 IAR bands. The frequency of these IAR bands is detailed in Appendix I. MTUs should be capable of being configured to notch amateur radio bands individually based on the needed protection. + +Within a notch, all subcarriers shall be turned off and the notching mask (NM) shall be equal to LPM –20 dB. + +NOTE 1 – Subcarriers at either side of the masked subcarriers may also need to be turned off in order to meet the requirement on TxPSDM notch depth. + +For a notch, two PSD masks are defined: + +- Narrowband transmit PSD mask (TXPSDM\_N) + +This mask is defined to verify the PSD using an MBW=10 kHz centred on the frequency in question. + +The TXPSDM\_N is defined as the maximum of the NM and a lower limit of –100 dBm/Hz: + +$$TxPSDM\_N = \max[NM, -100 \text{ dBm/Hz}].$$ + +- Wideband transmit PSD mask (TXPSDM\_W) + +This mask is defined to verify a mathematically calculated wideband average PSD (PSD\_W), obtained by averaging the narrowband measurements (PSD\_N) (measured in an MBW=10 kHz) over a 1 MHz window centred on the frequency in question: + +$$PSD\_W(f) = 10 \times \log_{10} \left( \left( \frac{1}{100} \right) \times \sum_{i=(-49)}^{50} 10^{\left( \frac{PSD\_N(f+i \times 10kHz)}{10} \right)} \right)$$ + +with: + +PSD\_N( $f$ ) the narrowband measurement at frequency $f$ , expressed in dBm/Hz + +PSD\_W( $f$ ) the mathematically calculated wideband average PSD at frequency $f$ , expressed in dBm/Hz. + +The TXPSDM\_W is defined as the maximum of the notch mask (NM) and a lower limit as defined in Table 6-1 for the frequency in question: + +$$TxPSDM\_W(f) = \max[NM(f), \text{lower limit}(f)].$$ + +**Table 6-1 – TXPSDM\_W lower limit requirements** + +| Frequency MHz | TXPSDM_W lower limit [dBm/Hz] | +|---------------|-------------------------------| +| 2.0-4.0 | –100 | +| 4.0-5.0 | –110 | +| > 5.0 | –112 | + +For notches that are narrower than 1 MHz: + +- the transmit PSD is only required to satisfy the narrowband transmit PSD mask TXPSDM\_N, and this for frequencies $(SC_{start} \times f_{sc} + \frac{1}{2} \times MBW) < f < (SC_{stop} \times f_{sc} - \frac{1}{2} \times MBW)$ . + +For notches that are 1 MHz or wider: + +- the transmit PSD is required to satisfy the narrowband transmit PSD mask TxPSDM\_N for frequencies $(SC_{start} \times f_{SC} + \frac{1}{2} \times MBW) < f < (SC_{stop} \times f_{SC} - \frac{1}{2} \times MBW)$ , and +- the wideband average transmit PSD ( $PSD\_W(f)$ ) is required to satisfy the wideband transmit PSD mask TxPSDM\_W for frequencies $(SC_{start} \times f_{SC} + \frac{1}{2} \times MBW + 0.5\text{MHz}) < f < (SC_{stop} \times f_{SC} - \frac{1}{2} \times MBW - 0.5\text{MHz})$ . The mask value to be compared against shall be the maximum value the mask takes within the 1 MHz window $[f - 0.5\text{ MHz}, f + 0.5\text{ MHz}]$ . + +Appendix II details the frequencies for the broadcast radio services (frequency modulation (FM), digital audio broadcasting (DAB), aeronautical communication and radio navigation). + +FM, DAB and other radio services may require different notch configurations depending on the characteristics of the specific radio service. + +NOTE 2 – NM may be used to notch individual broadcast stations depending on spectrum utilization. + +## 6.6 Low frequency edge stop-band masking + +For the low frequency edge stop-band mask (LESM), two PSD masks are defined: + +- Narrowband transmit PSD mask (TxPSDM\_N) + +This mask is defined to verify the PSD using an $MBW=10\text{ kHz}$ centred on the frequency in question. + +The TxPSDM\_N is defined as shown in Figure 6-1, where $PSD_{tr3}$ is the value of the in-band LPM at frequency $f_{tr3}$ . The mask values in the transition band are obtained using linear interpolation in dB over a linear frequency scale. + +The transmit PSD is required to satisfy the narrowband transmit PSD mask TxPSDM\_N, for frequencies $(0.5\text{ MHz} + \frac{1}{2} \times MBW) < f < (f_{tr3} - \frac{1}{2} \times MBW)$ , where $f_{tr1} \leq f_{tr3} \leq 30\text{ MHz}$ . The PSD values above the transition frequency $f_{tr3}$ are considered as in-band and defined in clause 7.2.1.1. + +![Figure 6-1: Low-frequency edge stop-band mask. The graph shows PSD (dBm/HZ) on the y-axis and Frequency (kHz) on the x-axis. The y-axis has labels for PSD_tr3, -80, and -100. The x-axis has labels for 500 and f_tr3. The mask is a step function that is -100 dBm/HZ from 500 kHz to a transition band starting at f_tr3 - 175 kHz. In this 175 kHz transition band, the PSD increases linearly to -80 dBm/HZ at f_tr3. For frequencies above f_tr3, the PSD is constant at PSD_tr3.](79d61011f426d34fb542d86176482d2c_img.jpg) + +Figure 6-1: Low-frequency edge stop-band mask. The graph shows PSD (dBm/HZ) on the y-axis and Frequency (kHz) on the x-axis. The y-axis has labels for PSD\_tr3, -80, and -100. The x-axis has labels for 500 and f\_tr3. The mask is a step function that is -100 dBm/HZ from 500 kHz to a transition band starting at f\_tr3 - 175 kHz. In this 175 kHz transition band, the PSD increases linearly to -80 dBm/HZ at f\_tr3. For frequencies above f\_tr3, the PSD is constant at PSD\_tr3. + +Figure 6-1 – Low-frequency edge stop-band mask + +- Wideband transmit PSD mask (TxPSDM\_W) + +This mask is defined to verify a mathematically calculated wideband average PSD over a 1 MHz window ( $PSD\_W(f)$ ) as defined in clause 6.5. + +The TXPSDM\_W( $f$ ) is defined in Table 6-2 for the frequency in question. + +The wideband average transmit PSD ( $PSD\_W(f)$ ) is required to satisfy the wideband transmit PSD mask TxPSDM\_W for frequencies $(2.0 \text{ MHz} + \frac{1}{2} \times \text{MBW} + 0.5 \text{ MHz}) < f < (f_{tr3} - 175 \text{ kHz} - \frac{1}{2} \times \text{MBW} - 0.5 \text{ MHz})$ . The mask value to be compared against shall be the maximum value the mask takes within the 1 MHz window $[f - 0.5 \text{ MHz}, f + 0.5 \text{ MHz}]$ . + +**Table 6-2 – LESM TXPSDM\_W requirements** + +| Frequency (MHz) | LESM TXPSDM_W (dBm/Hz) | +|-----------------|------------------------| +| 2.0 to 4.0 | -100 | +| 4.0 to 5.0 | -110 | +| > 5.0 | -112 | + +# 7 Specification of spectral content + +## 7.1 PSD type + +Each PSD type specifies normative values for the following parameter: + +- the limit PSD mask (LPM); + +Table 7-1 shows the valid parameters for each PSD type. + +**Table 7-1 – PSD type parameters** + +| Parameter | PSD type (Note) | | +|-----------|------------------|-------------------| +| | 424 MHz | 848 MHz | +| LPM | See clause 7.2.1 | for further study | + +NOTE – Future PSD types may be defined provided that they are within the bounds of the limit PSD mask specified in this Recommendation. + +## 7.2 PSD mask specifications + +### 7.2.1 Limit PSD mask (LPM) + +The limit PSD mask (LPM) represents the absolute maximum that the TxPSDM shall never exceed. The in-band LPM for the 424 MHz PSD type is presented in clause 7.2.1.1. The out-of-band LPMs are defined in clause 7.2.1.2. + +#### 7.2.1.1 In-band LPM + +The in-band LPM for the 424 MHz PSD type is shown in Figure 7-1. The parameters for this LPM is presented in Table 7-2. + +![Figure 7-1: In-band limit PSD mask for 424 MHz PSD type. The graph shows PSD in dBm/Hz on the y-axis with marked levels at -65, -73, -76, and -79. The x-axis represents Frequency in kHz with marked points at f_tr1, 30, 106, 212, and f_tr2. The mask starts at -65 dBm/Hz at f_tr1, stays flat until 30 kHz, then drops to -73 dBm/Hz. From 30 kHz, it slopes down through -76 dBm/Hz at 106 kHz to -79 dBm/Hz at 212 kHz, then remains flat at -79 dBm/Hz until f_tr2. A dashed line indicates the slope between 30 and 212 kHz.](7c1f9e78e0f033d391b687f1652f6e47_img.jpg) + +Figure 7-1: In-band limit PSD mask for 424 MHz PSD type. The graph shows PSD in dBm/Hz on the y-axis with marked levels at -65, -73, -76, and -79. The x-axis represents Frequency in kHz with marked points at f\_tr1, 30, 106, 212, and f\_tr2. The mask starts at -65 dBm/Hz at f\_tr1, stays flat until 30 kHz, then drops to -73 dBm/Hz. From 30 kHz, it slopes down through -76 dBm/Hz at 106 kHz to -79 dBm/Hz at 212 kHz, then remains flat at -79 dBm/Hz until f\_tr2. A dashed line indicates the slope between 30 and 212 kHz. + +**Figure 7-1 – In-band limit PSD mask for 424 MHz PSD type** + +**Table 7-2 – Parameters of in-band LPM for 424 MHz PSD type** + +| Parameter | Frequency (MHz) | PSD (dBm/Hz) | Description | +|-----------|-----------------|--------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $f_{tr1}$ | 2 | –65 | The LPM below $f_{tr1}$ is defined in clause 7.2.1.2. | +| | 30 | –65 | | +| | 30 | –73 | The PSD limit values between the points listed shall be obtained by linear interpolation in dB over a linear frequency scale. The LPM above $f_{tr2}$ is defined in clause 7.2.1.2. | +| | 106 | –76 | | +| | 212 | –79 | | +| $f_{tr2}$ | 424 | –79 | | + +NOTE – When additional spectrum shaping is used as described in clause 6 (for example, to provide spectrum compatibility or to comply with wideband power limit), various parts of the TxPSDM could be reduced by switching subcarriers off or reducing their transmit power. Additional frequency notches may also be applied if required. + +#### 7.2.1.2 Out-of-band LPM + +The out-of-band LPM shall be as shown in Figure 7-2 for the low-frequency edge, and in Figure 7-3 for the high-frequency edge, where $PSD_{tr1}$ is the value of the in-band LPM at frequency $f_{tr1}$ and $PSD_{tr2}$ is the value of the in-band LPM at frequency $f_{tr2}$ . The parameters for these LPMs are presented in Table 7-3 and Table 7-4, respectively. + +The out-of-band LPM applies for frequencies below the low-edge transition frequency $f_{tr1}$ and for frequencies above the high-edge transition frequency $f_{tr2}$ . The PSD values between the transition frequencies $f_{tr1}$ and $f_{tr2}$ are considered as in-band and defined in clause 7.2.1.1. + +![Figure 7-2: Low-frequency edge out-of-band LPM. A graph showing Power Spectral Density (PSD) in dBm/HZ versus Frequency in kHz. The y-axis has labels PSDtr1, -80, -90, -97.5, and -100. The x-axis has labels 4, 20, 500, and ftr1. The graph shows a piecewise linear function: from 4 kHz to 20 kHz, it rises from -97.5 dBm/HZ to -90 dBm/HZ; from 20 kHz to 500 kHz, it is constant at -90 dBm/HZ; from 500 kHz to ftr1, it drops to -100 dBm/HZ and then rises linearly to -80 dBm/HZ at ftr1. A horizontal dashed line at PSDtr1 is shown above -80 dBm/HZ. A shaded region is shown below 4 kHz. A note 'See ITU-T G.993.2 Annex A, B, C or N' is present. A horizontal double-headed arrow indicates a 175 kHz width near ftr1. The label G.9710(20)_F7-2 is at the bottom right.](71ab4df17511d75261da8d462d643b1a_img.jpg) + +Figure 7-2: Low-frequency edge out-of-band LPM. A graph showing Power Spectral Density (PSD) in dBm/HZ versus Frequency in kHz. The y-axis has labels PSDtr1, -80, -90, -97.5, and -100. The x-axis has labels 4, 20, 500, and ftr1. The graph shows a piecewise linear function: from 4 kHz to 20 kHz, it rises from -97.5 dBm/HZ to -90 dBm/HZ; from 20 kHz to 500 kHz, it is constant at -90 dBm/HZ; from 500 kHz to ftr1, it drops to -100 dBm/HZ and then rises linearly to -80 dBm/HZ at ftr1. A horizontal dashed line at PSDtr1 is shown above -80 dBm/HZ. A shaded region is shown below 4 kHz. A note 'See ITU-T G.993.2 Annex A, B, C or N' is present. A horizontal double-headed arrow indicates a 175 kHz width near ftr1. The label G.9710(20)\_F7-2 is at the bottom right. + +**Figure 7-2 – Low-frequency edge out-of-band LPM** + +Requirements for frequencies below 4 kHz are specified in Annexes A, B, C and N of [ITU-T G.993.2] for the regions of North America, Europe, Japan and China, respectively. + +![Figure 7-3: High-frequency edge out-of-band LPM. A graph showing Power Spectral Density (PSD) in dBm/HZ versus Frequency in kHz. The y-axis has labels PSDtr2 and -110. The x-axis has labels ftr2 and Frequency (kHz). The graph shows a piecewise linear function: from ftr2 to ftr2 + Δfth, it drops linearly from PSDtr2 to -110 dBm/HZ; from ftr2 + Δfth onwards, it is constant at -110 dBm/HZ. Vertical dashed lines mark the start and end of the transition. A horizontal double-headed arrow indicates the width Δfth. The label G.9710(20)_F7-3 is at the bottom right.](0a8d173734e4e46c344178e8d21bcbc3_img.jpg) + +Figure 7-3: High-frequency edge out-of-band LPM. A graph showing Power Spectral Density (PSD) in dBm/HZ versus Frequency in kHz. The y-axis has labels PSDtr2 and -110. The x-axis has labels ftr2 and Frequency (kHz). The graph shows a piecewise linear function: from ftr2 to ftr2 + Δfth, it drops linearly from PSDtr2 to -110 dBm/HZ; from ftr2 + Δfth onwards, it is constant at -110 dBm/HZ. Vertical dashed lines mark the start and end of the transition. A horizontal double-headed arrow indicates the width Δfth. The label G.9710(20)\_F7-3 is at the bottom right. + +**Figure 7-3 – High-frequency edge out-of-band LPM** + +**Table 7-3 – Parameters of low-frequency edge out-of-band LPM** + +| $f_{tr1}$
(MHz) | $PSD_{tr1}$
(dBm/Hz) | Description | +|--------------------|-------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 2 | -65 |

The PSD limit at transition frequency f_{tr1} drops from PSD_{tr1} to -80 dBm/Hz.

The PSD limit in the transition band shall be obtained by linear interpolation in dB over a linear frequency scale.

The PSD limit between 4 and 20 kHz shall be obtained by linear interpolation in dB over a \log(f) scale.

Subcarriers below f_{tr1} shall not be used for transmission (neither data nor any auxiliary information).

| + +**Table 7-4 – Parameters of high-frequency edge out-of-band LPM** + +| $f_{tr2}$
(MHz) | $PSD_{tr2}$
(dBm/Hz) | Transition band, $\Delta f_{th}$
(MHz) | Description | +|--------------------|-------------------------|-------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 424 | -79 | 80 |

The PSD limit in the transition band (\Delta f_{th}) shall be obtained by linear interpolation in dB over linear frequency scale.

Subcarriers above f_{tr2} shall not be used for transmission (neither data nor any auxiliary information).

| + +#### 7.2.2 Permanently masked subcarriers + +For the 424 MHz PSD type, subcarriers with indices from 0 to 39 (inclusive) shall be permanently masked. They shall not be used for transmission (neither for data nor for any auxiliary information). + +# 8 Transmit PSD verification + +The values of the transmit PSD mask are defined in this Recommendation under the assumption that transmission is continuous. In systems using time-division duplexing (TDD) mode, transmission in a particular direction is not continuous but occurs only during designated time periods. In systems using full duplex (FDX) mode, in a given transmission direction, the transmit PSD in the full duplex compatible downstream sub-frame (FDS) may be different from that of the full duplex compatible upstream sub-frame (FUS). These shall be taken into account by the applied measurement procedure. + +The measurement bandwidth (MBW) for evaluation of the PSD shall be as defined in Table 8-1. The measurement bandwidth shall be centred on the frequency in question. + +The mask value to be compared against shall be the maximum value the mask takes within a window $[f - \frac{1}{2} \times \text{MBW}, f + \frac{1}{2} \times \text{MBW}]$ . + +NOTE – If in a certain frequency range both a narrowband transmit PSD mask (TXPSDM\_N) and a wideband transmit PSD mask (TXPSDM\_W) are defined, the MBW values defined in this clause relate to the narrowband PSD measurements $PSD\_N$ . + +PSD masks are specified with respect to a reference termination impedance, as defined in clauses P.1 and Q.1. + +**Table 8-1 – Measurement bandwidth settings for transmit PSD verification** + +| Frequency band | Measurement bandwidth (MBW) | +|---------------------------------------------------------------------------------------------------|------------------------------------| +| $4 \text{ kHz} < f < 20 \text{ kHz}$ | 1 kHz | +| $20 \text{ kHz} < f < f_{ir1}$ | 10 kHz | +| $(f_{ir1} + \frac{1}{2} \times \text{MBW})$ to $(30 \text{ MHz} - \frac{1}{2} \times \text{MBW})$ | 1 MHz | +| $(30 \text{ MHz} + \frac{1}{2} \times \text{MBW})$ to $(f_{ir2} - \frac{1}{2} \times \text{MBW})$ | 1 MHz | +| $> f_{ir2}$ to 300 MHz | 100 kHz | +| Any notched frequency band | 10 kHz | + +## **Annex A to Annex O** + +*Annex A to Annex O have been intentionally left blank.* + +## Annex P + +### Adaptation to the twisted pair medium + +(This annex forms an integral part of this Recommendation.) + +### P.1 Termination impedance + +For a transceiver operating over twisted pairs, a termination impedance of $R_V = 100$ Ohm, purely resistive, at the U interface, shall be used for both the MTU-O and the MTU-R. In particular, $R_V = 100$ Ohm shall be used as a termination for the transmit PSD and aggregate transmit power definition and verification. + +## Annex Q + +### Adaptation to the coaxial cable medium + +(This annex forms an integral part of this Recommendation.) + +### **Q.1 Termination impedance** + +For a transceiver operating over coaxial cables, a termination impedance of $R_V = 75$ Ohm, purely resistive, at the U interface, shall be used for both the MTU-O and the MTU-R. In particular, $R_V = 75$ Ohm shall be used as a termination for the transmit PSD and aggregate transmit power definition and verification. + +### **Q.2 Transmit PSD verification** + +In systems operating over coaxial cables using FDX mode, in a given transmission direction, the transmit PSD shall be the same for both FDS and FUS. This shall be taken into account by the applied measurement procedure. + +## Appendix I + +### International amateur radio bands + +(This appendix does not form an integral part of this Recommendation.) + +Table I.1 lists the international amateur radio bands in the frequency range 1.8 MHz - 900 MHz. + +**Table I.1 – International amateur radio bands +in the frequency range 1.8 MHz - 900 MHz** + +| Band start
(kHz) | Band stop
(kHz) | +|-----------------------------|----------------------------| +| 1 800 | 2 000 | +| 3 500 | 4 000 | +| 5 351.5 | 5 366.5 | +| 7 000 | 7 300 | +| 10 100 | 10 150 | +| 14 000 | 14 350 | +| 18 068 | 18 168 | +| 21 000 | 21 450 | +| 24 890 | 24 990 | +| 28 000 | 29 700 | +| 50 000 | 54 000 | +| 69 900 | 70 500 | +| 144 000 | 148 000 | +| 219 000 | 225 000 | +| 420 000 | 450 000 | + +## Appendix II + +### Other aeronautical communication, radio navigation and broadcasting services + +(This appendix does not form an integral part of this Recommendation.) + +Table II.1 lists other aeronautical communication, radio navigation and broadcasting services in the frequency range 1.8 MHz - 900 MHz. + +**Table II.1 – Other aeronautical communication, radio navigation and broadcasting services in the frequency range 1.8 MHz - 900 MHz** + +| Service | Band start (kHz) | Band stop (kHz) | +|-----------------------------------------------------------------------------|------------------|-----------------| +| FM | 87 500 | 108 000 | +| Digital terrestrial television (Region 2) | 174 000 | 216 000 | +| Digital terrestrial television/Digital audio broadcasting (Regions 1 and 3) | 174 000 | 230 000 | +| Smart grid utility management systems | 450 000 | 470 000 | +| COSPAS-SARSAT EPIRBs | 460 000 | 460 100 | + +## Appendix III + +### Definition of transmitter PSD (TXPSD) for non-continuous transmissions + +(This appendix does not form an integral part of this Recommendation.) + +This appendix provides a formal definition for transmitter power spectral density (TXPSD) for signals comprising a stream of symbols including quiet periods, such as those produced by time division duplexed DMT systems. + +This appendix defines TXPSD that is applicable to a stream of transmitted symbols, a punctured stream of symbols, or a continuous stream of symbols. Transmitted symbols are all symbols transmitted in the transmission period for the transmission direction. There are two transmission periods namely FDS and FUS in the PDX frame. The measurement of TXPSD is performed separately for the FDS and FUS transmission period. The quiet symbol positions in the transmission period are excluded. The particular measurement technique is beyond the scope of this Appendix. + +This appendix defines TXPSD in terms of an intermediate variable, "Transmitter Symbol PSD" (TXSPSD). TXSPSD is defined in relation to the expectation of the energy spectral density (ESD) of symbols transmitted in a particular direction. + +The ESD of a symbol voltage waveform $V_s(t)$ is derived into a reference impedance of 100 $\Omega$ . + +$$ESD(V_s, f) = \frac{1}{R_0} \left| \int_{-\infty}^{\infty} V_s(t) \cdot e^{-i2\pi ft} dt \right|^2 \text{ (in unit of Joule/Hz)}$$ + +$$R_0 = 100 \Omega$$ + +TXSPSD is derived from the Expectation of the ESD over a set of transmitted symbols within a transmission period (FDS or FUS). + +$$TXSPSD(f) = f_{DMT} \cdot E[ESD(V(t), f); V \in S] \text{ (in unit of W/Hz)}$$ + +$$S = \{S_0, S_1, \dots, S_N\}$$ + +$S_0, S_1, \dots, S_N$ is a valid sequence of transmitted symbols within a transmission period (FDS or FUS) + +$E[x]$ is the statistical expectation of $x$ . + +This normalization by the period of the symbol ensures that in the limit an infinite sequence of symbols has TXSPSD that converges to the classical PSD derived from the Fourier transform of the autocorrelation function. + +The verifiable TXPSD is defined in a particular bandwidth $bw$ as follows: + +$$TXPSD(bw, f) = 30 + 10 \times \log_{10} \left( \frac{1}{bw} \int_{f-\frac{bw}{2}}^{f+\frac{bw}{2}} TXSPSD(f_b) df_b \right) \text{ (in unit of dBm/Hz)}$$ + +$TXPSDM(f)$ is the maximum permitted level for $TXPSD(bw, f)$ of a long symbol sequence. + +Methods for compliance verification are out of the scope of this Recommendation. + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.973.1-200911-I_PDF-E/84a1d09fb489061482111515543b60dc_img.jpg b/marked/G/T-REC-G.973.1-200911-I_PDF-E/84a1d09fb489061482111515543b60dc_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..d7891ad4da866f8afa77ca25dc85476b390f8447 --- /dev/null +++ b/marked/G/T-REC-G.973.1-200911-I_PDF-E/84a1d09fb489061482111515543b60dc_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:4a02d9c72e32cfb302c5fd9b64b961d1940f565b2e5e663e9ed88d0336be29b1 +size 7391 diff --git a/marked/G/T-REC-G.973.1-200911-I_PDF-E/a234352dfaccdc24745c88eef7724cc6_img.jpg b/marked/G/T-REC-G.973.1-200911-I_PDF-E/a234352dfaccdc24745c88eef7724cc6_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..7ae3c829d3190589bca213afd89e74a9c224cf91 --- /dev/null +++ b/marked/G/T-REC-G.973.1-200911-I_PDF-E/a234352dfaccdc24745c88eef7724cc6_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:3a5483368031783938ed76cc17a795e4ee4744ca0536e6136a688b677e0cb131 +size 53567 diff --git a/marked/G/T-REC-G.973.1-200911-I_PDF-E/daa4a6fa7e2ba1954258f86b4928eb32_img.jpg b/marked/G/T-REC-G.973.1-200911-I_PDF-E/daa4a6fa7e2ba1954258f86b4928eb32_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..ba547130c5f4ff387f708ca8212a8c842f3ae648 --- /dev/null +++ b/marked/G/T-REC-G.973.1-200911-I_PDF-E/daa4a6fa7e2ba1954258f86b4928eb32_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:33dbca9109193af2e61d77a0ba9b1ce964cb3550a00bfa6f23b777842a12d51d +size 16763 diff --git a/marked/G/T-REC-G.973.1-200911-I_PDF-E/raw.md b/marked/G/T-REC-G.973.1-200911-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..ff753cb9fd9aed20bd4d47a25c3e4e94d4b0d639 --- /dev/null +++ b/marked/G/T-REC-G.973.1-200911-I_PDF-E/raw.md @@ -0,0 +1,464 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.973.1** + +(11/2009) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical fibre +submarine cable systems + +--- + +**Longitudinally compatible DWDM applications +for repeaterless optical fibre submarine cable +systems** + +Recommendation ITU-T G.973.1 + +![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking it, symbolizing global communication. The text "ITU" is prominently displayed in blue, with "International Telecommunication Union" written in smaller blue text to the right. + +ITU logo + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **Recommendation ITU-T G.973.1** + +## **Longitudinally compatible DWDM applications for repeaterless optical fibre submarine cable systems** + +## **Summary** + +Recommendation ITU-T G.973.1 provides physical layer specifications for dense wavelength division multiplexing (DWDM) applications for repeaterless optical fibre submarine cable systems. Longitudinally compatible applications for DWDM applications for repeaterless optical fibre submarine cable systems are described for point-to-point, multichannel line systems without remotely pumped optical amplifiers. The primary purpose is to enable multiple vendors to design DWDM transmission equipment for submarine fibre links that are compliant with this Recommendation. + +## **History** + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.973.1 | 2009-11-13 | 15 | + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2010 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +| | Page | +|-----------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Terms and definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Classification of optical interfaces..... | 3 | +| 6.1 Applications..... | 3 | +| 6.2 Reference configurations..... | 3 | +| 7 Single-span longitudinal compatibility ..... | 4 | +| 8 Parameters..... | 4 | +| 8.1 Maximum attenuation..... | 4 | +| 8.2 Fibre types ..... | 4 | +| 8.3 Wavelength ranges ..... | 5 | +| 8.4 Maximum chromatic dispersion ..... | 5 | +| 8.5 Minimum local chromatic dispersion coefficient..... | 5 | +| 8.6 Maximum differential group delay..... | 6 | +| 8.7 Minimum effective area ..... | 7 | +| 9 Characteristics and performance of the system ..... | 7 | +| 9.1 System reliability performance..... | 7 | +| 9.2 System capacity upgrading..... | 7 | +| 10 Characteristics and performance of the submarine cable ..... | 8 | +| 11 Optical safety considerations..... | 8 | +| Bibliography..... | 9 | + + + +## Recommendation ITU-T G.973.1 + +## Longitudinally compatible DWDM applications for repeaterless optical fibre submarine cable systems + +# 1 Scope + +This Recommendation provides physical layer specifications for dense wavelength division multiplexing (DWDM) applications in point-to-point repeaterless optical fibre submarine cable systems. The goal is to enable longitudinally compatible applications. + +The primary purpose is to enable multiple vendors to provide transmission equipment for submarine fibre links that are compliant with this Recommendation. + +This Recommendation includes a generic reference model for the physical layer applications. The specifications take into account parameters such as maximum attenuation, fibre types, wavelength ranges, maximum chromatic dispersion, minimum local chromatic dispersion coefficient, maximum differential group delay, and minimum effective area. + +This Recommendation focuses on repeaterless optical fibre submarine cable systems without remotely pumped optical amplifiers. + +This Recommendation presumes that the optical tributary signals transported within optical channels are digital. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.650.2] Recommendation ITU-T G.650.2 (2007), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable*. +- [ITU-T G.652] Recommendation ITU-T G.652 (2009), *Characteristics of a single-mode optical fibre and cable*. +- [ITU-T G.653] Recommendation ITU-T G.653 (2006), *Characteristics of a dispersion-shifted single-mode optical fibre and cable*. +- [ITU-T G.654] Recommendation ITU-T G.654 (2006), *Characteristics of a cut-off shifted single-mode optical fibre and cable*. +- [ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable*. +- [ITU-T G.656] Recommendation ITU-T G.656 (2006), *Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport*. +- [ITU-T G.959.1] Recommendation ITU-T G.959.1 (2009), *Optical transport network physical layer interfaces*. +- [ITU-T G.978] Recommendation ITU-T G.978 (2006), *Characteristics of optical fibre submarine cables*. + +# **3 Terms and definitions** + +## **3.1 Terms defined elsewhere** + +This Recommendation uses the following terms defined elsewhere: + +**3.1.1** The following term is defined in [ITU-T G.650.2]: + +- polarization mode dispersion (PMD) + +**3.1.2** The following term is defined in [b-ITU-T G.696.1]: + +- client class + +**3.1.3** The following term is defined in [b-ITU-T G.709]: + +- optical transport hierarchy (OTH) + +**3.1.4** The following term is defined in [b-ITU-T G.780]: + +- synchronous digital hierarchy (SDH) + +**3.1.5** The following terms are defined in [b-ITU-T G.972]: + +- dense wavelength division multiplexing (DWDM) +- dense wavelength division multiplexing system (DWDMS) +- wavelength division multiplexing (WDM) + +**3.1.6** The following terms are defined in [ITU-T G.959.1]: + +- multichannel receive main path interface reference point (MPI-RM) +- multichannel source main path interface reference point (MPI-SM) + +**3.1.7** The following term is defined in [b-ITU-T G-Sup.40]: + +- dispersion compensating single-mode fibre (DCF) + +# **4 Abbreviations and acronyms** + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------------------|-----------------------------------------------| +| A eff | Effective area | +| CSF | Cut-off Shifted single-mode Fibre | +| DCF | Dispersion Compensating single-mode Fibre | +| DGD | Differential Group Delay | +| DSF | Dispersion Shifted single-mode Fibre | +| DWDM | Dense Wavelength Division Multiplexing | +| DWDMS | Dense Wavelength Division Multiplexing System | +| FWM | Four-Wave Mixing | +| LEF | Large Effective area single-mode Fibre | +| MPI | Main Path Interface | +| MUX | Multiplexer | +| NDF | Negative Dispersion single-mode Fibre | +| NRZ | Non-Return to Zero | +| NZDSF | Non-Zero Dispersion Shifted single-mode Fibre | +| OA | Optical Amplifier | + +| | | +|-------|------------------------------------------------| +| OTH | Optical Transport Hierarchy | +| PMD | Polarization Mode Dispersion | +| RZ | Return to Zero | +| SDH | Synchronous Digital Hierarchy | +| TTE | Terminal Transmission Equipment | +| WDMS | Wavelength Division Multiplexing System | +| WNZDF | Wideband Non-Zero Dispersion single-mode Fibre | + +# 5 Conventions + +This clause is intentionally left blank. + +# 6 Classification of optical interfaces + +## 6.1 Applications + +This Recommendation addresses longitudinally compatible DWDM application in point-to-point repeaterless optical fibre submarine cable system. + +## 6.2 Reference configurations + +For the purpose of this Recommendation, the relevant reference points applicable to the DWDM application for point-to-point repeaterless optical fibre submarine cable systems are shown in Figure 6-1. + +![Figure 6-1: Reference configuration for DWDM system. The diagram shows two main components connected by optical fibers. The left component is a transmitter (Tx) side with multiple transmitters (Tx1 to Txn) connected to a Multiplexer (MUX), which is then connected to an Optical Amplifier (OA). The output of the OA is labeled MPI-SM. The right component is a receiver (Rx) side with an Optical Amplifier (OA) connected to a Demultiplexer (DEMUX), which is then connected to multiple receivers (Rx1 to Rxn). The input of the OA is labeled MPI-RM. The two components are connected by a central optical fiber with two repeaters (represented by two overlapping circles). The fiber between the left OA and the first repeater is labeled MPI-RM, and the fiber between the second repeater and the right OA is labeled MPI-SM.](a234352dfaccdc24745c88eef7724cc6_img.jpg) + +Figure 6-1: Reference configuration for DWDM system. The diagram shows two main components connected by optical fibers. The left component is a transmitter (Tx) side with multiple transmitters (Tx1 to Txn) connected to a Multiplexer (MUX), which is then connected to an Optical Amplifier (OA). The output of the OA is labeled MPI-SM. The right component is a receiver (Rx) side with an Optical Amplifier (OA) connected to a Demultiplexer (DEMUX), which is then connected to multiple receivers (Rx1 to Rxn). The input of the OA is labeled MPI-RM. The two components are connected by a central optical fiber with two repeaters (represented by two overlapping circles). The fiber between the left OA and the first repeater is labeled MPI-RM, and the fiber between the second repeater and the right OA is labeled MPI-SM. + +Figure 6-1 – Reference configuration for DWDM system + +The reference points MPI-SM and MPI-RM in Figure 6-1 are defined as follows, using the same nomenclature as in [ITU-T G.959.1]: + +- MPI-SM is a (multichannel) reference point on the optical fibre just after the optical network element transport interface output optical connector; + +- MPI-RM is a (multichannel) reference point on the optical fibre just before the optical network element transport interface input optical connector. + +# 7 Single-span longitudinal compatibility + +The applications covered by this Recommendation are single-span longitudinally compatible. It is defined as follows. + +The systems are defined to be "longitudinally compatible" when both ends of an optical section are terminated by equipment from the same manufacturer. Systems from different vendors can be installed on the various optical fibres of the cable. In this case only the cable characteristics (attenuation, dispersion, DGD) are specified. A single-span longitudinally compatible system is illustrated in Figure 7-1. + +![Diagram illustrating single-span longitudinal compatibility. A transmitter (Tx) and a receiver (Rx) are connected by an optical fibre. The Tx is labeled 'Vendor A' and 'Vendor B'. The Rx is labeled 'Vendor A' and 'Vendor B'. The fibre has a splice or connector in the middle.](daa4a6fa7e2ba1954258f86b4928eb32_img.jpg) + +The diagram shows a Tx (Transmitter) on the left and an Rx (Receiver) on the right, connected by a horizontal line representing an optical fibre. In the center of the fibre, there are three overlapping circles representing a splice or connector. Above the Tx is the label 'Vendor A' and below it is 'Vendor B'. Similarly, above the Rx is 'Vendor A' and below it is 'Vendor B'. This indicates that both ends of the optical section are terminated by equipment from the same manufacturer (Vendor A or Vendor B). + +Diagram illustrating single-span longitudinal compatibility. A transmitter (Tx) and a receiver (Rx) are connected by an optical fibre. The Tx is labeled 'Vendor A' and 'Vendor B'. The Rx is labeled 'Vendor A' and 'Vendor B'. The fibre has a splice or connector in the middle. + +**Figure 7-1 – Single-span longitudinal compatibility** + +NOTE – For multi-span systems, longitudinal compatibility is so far impossible to achieve because all fibre pairs make use of the same repeaters. It means that each amplifier module of each fibre is located into the same repeater housing which is supplied by one single vendor. The same applies for the other equipment of the wet plant (e.g., equalizers, branching units). + +# 8 Parameters + +## 8.1 Maximum attenuation + +The maximum attenuation from MPI-SM to MPI-RM is specified for an operating wavelength region, which include loss caused by splices, connectors, optical attenuators and other passive optical devices (if used) as well as fibre loss. + +The maximum attenuation coefficient of each G.652, G.653, G.654, G.655 and G.656 fibre is specified in the corresponding ITU-T Recommendations. In these Recommendations, the maximum attenuation coefficients at 1550 nm of cabled fibres are specified in the 0.22 to 0.4 dB/km range. It should be noted that a submarine transmission system sometimes requires smaller attenuation value. + +The typical maximum attenuation value is for further study. + +## 8.2 Fibre types + +In submarine systems, several types of optical fibres are used to construct an optical path. These include the following: + +- single-mode fibres defined in ITU-T Recommendations: + - non-dispersion shifted single-mode fibre (SMF) defined in [ITU-T G.652]; + - dispersion shifted single-mode fibre (DSF) defined in [ITU-T G.653]; + - cut-off shifted single-mode fibre (CSF) defined in [ITU-T G.654]; + - non-zero dispersion-shifted single-mode fibre (NZDSF) defined in [ITU-T G.655]; + - wideband non-zero dispersion single-mode fibre (WNZDF) defined in [ITU-T G.656]; + +- positive dispersion single-mode fibre (PDF); +- negative dispersion single-mode fibre (NDF); +- large effective area single-mode fibre (LEF); +- dispersion compensating single-mode fibre (DCF). + +Depending on the system specifications, various combinations of these fibre types may be used to ensure that the system performs correctly. Further information about each type of fibre can be found in [ITU-T G.978]. + +## 8.3 Wavelength ranges + +The operating wavelength range consists of one or more of the wavelength bands, as defined in [b-ITU-T G-Sup.41]. See Table 8-1. + +**Table 8-1 – Wavelength ranges** + +| S | Descriptor | Range (nm) | +|---|------------------|--------------| +| O | Original | 1260 to 1360 | +| E | Extended | 1360 to 1460 | +| S | Short wavelength | 1460 to 1530 | +| C | Conventional | 1530 to 1565 | +| L | Long wavelength | 1565 to 1625 | + +## 8.4 Maximum chromatic dispersion + +This parameter defines the maximum value of the optical path chromatic dispersion from $\text{MPI-S}_M$ to $\text{MPI-R}_M$ in the operating wavelength region. The chromatic dispersion of optical path must be held within certain limits to ensure acceptable system operation, which is expressed in ps/nm. Chromatic dispersion can be calculated as the product of the chromatic dispersion coefficient of each fibre (ps/nm·km) and its length (km). It is noted that, for submarine systems, the optical path could consist of several types of fibres with different chromatic dispersion coefficients. + +The chromatic dispersion coefficient of each G.652, G.653, G.654, G.655 and G.656 fibre is specified in the corresponding ITU-T Recommendations. + +Further information regarding chromatic dispersion impairment can be found in [b-ITU-T G-Sup.39]. + +## 8.5 Minimum local chromatic dispersion coefficient + +The chromatic dispersion value of an optical path must be held at an acceptable system tolerance value. On the other hand, for DWDM systems, the local dispersion coefficient of the transmission fibre must have a minimum value to avoid the impairment caused by non-linear effects such as four-wave mixing (FWM) and cross-phase modulation (XPM). These non-linear effects in a fibre are strong when the chromatic dispersion coefficient at the operating wavelength region is close to zero and they induce degradation in the transmission performance. The impairment caused by non-linear effects depends on many aspects of system design such as the channel spacing, power level and path length. In general, DWDM systems with narrow channel spacing, high power level and long path length are more likely to suffer from these effects. In such systems, it is especially required to take particular care over the minimum value of the local chromatic dispersion coefficient to prevent the occurrence of non-linear effects. + +Further information regarding non-linear effects can be found in [b-ITU-T G.663], and [b-ITU-T G-Sup.39]. + +## 8.6 Maximum differential group delay + +The maximum differential group delay (DGD) applies to the whole link between a transmitter (shown as "Tx" connected to a MUX in Figure 6-1) and the corresponding receiver ("Rx" connected to the DEMUX in Figure 6-1). + +The equation below can be used to calculate the maximum DGD of a link (containing multiple components and fibre sections) with a defined probability of being exceeded. + +$$DGD_{max\_link} = \left[ DGD_{max\_F}^2 + S^2 \sum_i PMD_{Ci}^2 \right]^{1/2}$$ + +where: + +$DGD_{max\_link}$ : is the maximum link DGD (ps); + +$DGD_{max\_F}$ : is the maximum concatenated optical fibre cable DGD (ps); + +$S$ : is Maxwell adjustment factor (see Table 8-2); + +$PMD_{Ci}$ : is PMD value of the $i$ th component (ps). + +This equation assumes that the statistics of the instantaneous DGD are approximated by a Maxwell distribution, with the probability of the instantaneous DGD exceeding $DGD_{max\_link}$ being controlled by the value of the Maxwell adjustment factor taken from Table 8-2. + +**Table 8-2 – S values and probabilities** + +| Ratio of max. to mean (S) | Probability of exceeding max. | Ratio of max. to mean (S) | Probability of exceeding max. | +|---------------------------|-------------------------------|---------------------------|-------------------------------| +| 3 | $4.2 \times 10^{-5}$ | 4 | $7.4 \times 10^{-9}$ | +| 3.2 | $9.2 \times 10^{-6}$ | 4.2 | $9.6 \times 10^{-10}$ | +| 3.4 | $1.8 \times 10^{-6}$ | 4.4 | $1.1 \times 10^{-10}$ | +| 3.6 | $3.2 \times 10^{-7}$ | 4.6 | $1.2 \times 10^{-11}$ | +| 3.8 | $5.1 \times 10^{-8}$ | | | + +Further details can be found in [ITU-T G.650.2] and in [b-ITU-T G.691]. The value of $DGD_{max\_F}$ (the maximum DGD due to the fibre part) can either be measured or, alternatively, an upper limit can be calculated for a given fibre length using the $PMD_Q$ coefficient in the corresponding fibre Recommendation. + +The DGD limits for the entire link are given in Table 8-3 for NRZ systems and in Table 8-4 for RZ systems. + +**Table 8-3 – Maximum link differential group delay for NRZ** + +| Client class | Units | Value | +|--------------|-------|-------| +| 2.5G | ps | 120 | +| 10G | ps | 30 | +| 40G | ps | 7.5 | + +**Table 8-4 – Maximum link differential group delay for RZ** + +| Client class | Units | Value | +|--------------|-------|-------| +| 2.5G | ps | ffs | +| 10G | ps | ffs | +| 40G | ps | ffs | + +## 8.7 Minimum effective area + +Effective area is a parameter that is closely related to optical fibre non-linear effects and will affect the transmission quality of optical fibre systems. In submarine systems, large effective area single-mode fibre (LEF) could be used to reduce such non-linear effects. When adopting LEF, the minimum effective area of the fibre should be specified. + +The method for measuring the effective area $A_{eff}$ in a single-mode fibre is described in [ITU-T G.650.2]. + +# 9 Characteristics and performance of the system + +## 9.1 System reliability performance + +The reliability of the submarine portion of an optical fibre submarine cable system is generally characterized by: + +- The expected number of repairs requiring intervention by a cableship and due to system component (e.g., splices, transitions, etc.) failures during the system design life: + +The usual requirement for the reliability of a repeaterless system is less than one failure requiring cableship intervention during the system design life. + +- The system design life: + +The period of time over which the optical fibre submarine cable system is designed to be operational in conformance with its performance specification. Usually, the system design life is a period of 25 years starting at the provisional acceptance date of the system, i.e., the date following installation when the system is claimed to be compliant with the performance specifications. + +## 9.2 System capacity upgrading + +It may be advantageous to increase the transmission capacity by increasing the signal bit rate and/or the number of transmission channels (WDMS or DWDMs). Such upgrading can be beneficial because the reuse of cables can be achieved cost-effectively over the equipment's long life, typically 25 years. + +Bit-rate upgradeability demands that systems be constructed with cables optimized for the higher bit rate, while the lower bit-rate TTE may be initially used. Even after upgrading, the bit rate of TTE output must comply with SDH or OTH specifications to ensure compatibility with standard terrestrial equipment. + +Upgradeability also demands that the initially installed cable be capable of carrying the maximum number of channels expected in the future. Upgrading by increasing signal bit rate or by adding more channels is much different from many viewpoints of system design including the post-amplifier output power, pre-amplifier input power, power budget, signal-to-noise ratio, fibre chromatic dispersion, and fibre non-linearities. It is therefore recommended that the systems be designed properly considering the possibility of future upgrades. + +# **10 Characteristics and performance of the submarine cable** + +The recommended characteristics and performance of the submarine cable are given in [ITU-T G.978]. + +# **11 Optical safety considerations** + +While this Recommendation relates to the fibre infrastructure and does not specify the characteristics of the optical transmission systems operating over it, such systems may well operate at relatively high optical power levels. Information on optical safety considerations can be found in [b-ITU-T G.664], [b-IEC 60825-1], and [b-IEC 60825-2]. + +# Bibliography + +- [b-ITU-T G.663] Recommendation ITU-T G.663 (2000), *Application related aspects of optical amplifier devices and subsystems.* +- [b-ITU-T G.664] Recommendation ITU-T G.664 (2006), *Optical safety procedures and requirements for optical transport systems.* +- [b-ITU-T G.691] Recommendation ITU-T G.691 (2006), *Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers.* +- [b-ITU-T G.696.1] Recommendation ITU-T G.696.1 (2005), *Longitudinally compatible intra-domain DWDM applications.* +- [b-ITU-T G.707] Recommendation ITU-T G.707/Y.1322 (2007), *Network node interface for the synchronous digital hierarchy (SDH).* +- [b-ITU-T G.709] Recommendation ITU-T G.709/Y.1331 (2003), *Interfaces for the Optical Transport Network (OTN).* +- [b-ITU-T G.780] Recommendation ITU-T G.780/Y.1351 (2008), *Terms and definitions for synchronous digital hierarchy (SDH) networks.* +- [b-ITU-T G.972] Recommendation ITU-T G.972 (2008), *Definition of terms relevant to optical fibre submarine cable systems.* +- [b-ITU-T G.973] Recommendation ITU-T G.973 (2007), *Characteristics of repeaterless optical fibre submarine cable systems.* +- [b-ITU-T G-Sup.39] ITU-T G-series Recommendations – Supplement 39 (2008), *Optical system design and engineering considerations.* +- [b-ITU-T G-Sup.40] ITU-T G-series Recommendations – Supplement 40 (2006), *Optical fibre and cable Recommendations and standards guideline.* +- [b-ITU-T G-Sup.41] ITU-T G-series Recommendations – Supplement 41 (2007), *Design guidelines for optical fibre submarine cable systems.* +- [b-IEC 60825-1] IEC 60825-1 (2007), *Safety of laser products – Part 1: Equipment classification and requirements.* +- [b-IEC 60825-2] IEC 60825-2 (2007), *Safety of laser products – Part 2: Safety of optical fibre communication systems (OFCS).* + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9801-201308-I_PDF-E/raw.md b/marked/G/T-REC-G.9801-201308-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..74cced31f459a016661a0b46816f1ce109aa85e7 --- /dev/null +++ b/marked/G/T-REC-G.9801-201308-I_PDF-E/raw.md @@ -0,0 +1,766 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9801** + +(08/2013) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – Optical line systems for local and +access networks + +# --- Ethernet passive optical networks using OMCI + +Recommendation ITU-T G.9801 + +![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking it, and the text "ITU International Telecommunication Union" to its right. + +ITU logo + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9801 + +# Ethernet passive optical networks using OMCI + +# Summary + +Recommendation ITU-T G.9801 describes requirements and specifications of Ethernet passive optical network (EPON) systems using the ONU management and control interface (OMCI), which is called OMCI-EPON. + +OMCI-EPON is based on IEEE 802.3 and IEEE 1904.1 for user data transport, and applies Annex C of Recommendation ITU-T G.988 for its management. OMCI-EPON supports 1G-EPON, 10/1G-EPON and 10/10G-EPON architectures defined in IEEE 802.3, and provides a mechanism that enables coexistence with the existing PON systems using time division multiple access (TDMA) technologies and/or wavelength blocking filter (WBF). + +# History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------------| +| 1.0 | ITU-T G.9801 | 2013-08-29 | 15 | 11.1002/1000/12009-en | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +# INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2014 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +###### Page + +| | | | +|-----|----------------------------------------------------------------------------------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 5 | +| 5 | Conventions ..... | 6 | +| 6 | Architecture of the optical access network..... | 8 | +| 6.1 | Network architecture ..... | 8 | +| 6.2 | Reference architecture ..... | 8 | +| 6.3 | ODN architectures ..... | 9 | +| 7 | Scenarios and services ..... | 11 | +| 7.1 | Scenarios..... | 11 | +| 7.2 | Services..... | 12 | +| 7.3 | Maximum/Mean signal transfer delay tolerance ..... | 12 | +| 7.4 | Frame length..... | 12 | +| 7.5 | Synchronization features and quality ..... | 12 | +| 7.6 | QoS and traffic management ..... | 13 | +| 8 | Requirements ..... | 13 | +| 8.1 | Physical layer and MAC layer requirements ..... | 13 | +| 8.2 | System level requirements..... | 14 | +| 8.3 | Operational requirements ..... | 14 | +| 8.4 | Resilience and protection on ODN..... | 15 | +| 9 | Optical network requirements..... | 15 | +| 9.1 | Physical medium dependent (PMD) sublayer ..... | 15 | +| 9.2 | Media access control (MAC), extensions of the reconciliation sublayer (RS) and physical coding sublayer (PCS)/physical media attachment (PMA)..... | 15 | +| 9.3 | OMCI-EPON management ..... | 17 | +| | Bibliography..... | 18 | + + + +## Recommendation ITU-T G.9801 + +# Ethernet passive optical networks using OMCI + +# 1 Scope + +The Ethernet passive optical network (EPON) system is a general name for PON systems that are based on the IEEE 802.3 standard and the IEEE 1904.1 standard. This Recommendation focuses on EPON systems that apply the ONU management and control interface (OMCI) defined by [ITU-T G.988] to create an effective PON operation system. This Recommendation calls these EPON systems OMCI-EPON. + +OMCI-EPON includes 1G-EPON, 10/1G-EPON and 10/10G-EPON architectures defined in [IEEE 802.3]. + +The requirements and specifications of OMCI-EPON conform to [IEEE 802.3] and the IEEE 1904.1 Package B standard and to the operational requirements and specifications defined by Annex C of [ITU-T G.988]. The requirements and specifications of OMCI-EPON enable the use of OMCI to manage IEEE 802.3/IEEE 1904.1 Package B compliant systems, thus providing 1G-EPON and 10G-EPON solutions to network operators who prefer OMCI management. + +As much as possible, this Recommendation maintains backward compatibility with existing optical distribution networks (ODN) that comply with the existing PON systems defined by [IEEE 802.3] and ITU-T Recommendations such as [b-ITU-T G.983.x], [b-ITU-T G.984.x] and [b-ITU-T G.987.x]. Furthermore, this Recommendation provides a mechanism that enables coexistence with the existing PON systems using TDMA technologies and/or wavelength blocking filter (WBF). + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.902] Recommendation ITU-T G.902 (1995), *Framework Recommendation on functional access networks (AN) – Architecture and functions, access types, management and service node aspects.* +- [ITU-T G.984.1] Recommendation ITU-T G.984.1 (2008), *Gigabit-capable passive optical networks (GPON): General characteristics.* +- [ITU-T G.988] Recommendation ITU-T G.988 (2012), *Optical network unit management and control interface specification.* +- [IEEE 1904.1] IEEE 1904.1-2013, *IEEE Standard for Service Interoperability in Ethernet Passive Optical Networks (SIEPON).* +- [IEEE 802.3] IEEE 802.3-2012, *IEEE Standard for Ethernet.* + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +**3.1.1 access network (AN)** [ITU-T G.902]: An implementation comprising those entities (such as cable plant, transmission facilities, etc.) which provide the required transport bearer capabilities for the provision of telecommunications services between a service node interface (SNI) and each of the associated user-network interfaces (UNI). + +**3.1.2 Ethernet LAN service (E-LAN)** [b-MEF 6.1]: An Ethernet service type that is based on a multipoint-to-multipoint Ethernet virtual connection. + +**3.1.3 Ethernet line service (E-Line)** [b-MEF 6.1]: An Ethernet service type that is based on a point-to-point Ethernet virtual connection. + +**3.1.4 Ethernet tree service (E-Tree)** [b-MEF 6.1]: An Ethernet service type that is based on a rooted-multipoint Ethernet virtual connection. + +**3.1.5 Ethernet virtual connection (EVC)** [b-MEF 6.1]: An association of UNIs to which the exchange of service frames is limited. + +**3.1.6 service node (SN)** [ITU-T G.902]: A network element that provides access to various switched and/or permanent telecommunication services. + +**3.1.7 service node interface (SNI)** [ITU-T G.902]: An interface which provides customer access to a service node. + +**3.1.8 user-network interface (UNI)** [b-ITU-T I.112]: The interface between the terminal equipment and a network termination at which interface the access protocols apply. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +*Terms related to optical access architecture* + +**3.2.1 Ethernet passive optical network (EPON)**: A general name for PON systems that are based on the [IEEE 802.3] standard and the [IEEE 1904.1] standard. + +**3.2.2 OMCI-EPON**: An EPON system that applies the ONU Management and Control Interface (OMCI) defined by [ITU-T G.988]. + +**3.2.3 optical access network (OAN)**: A part of an access network whose network elements are interconnected by optical communication channels. + +NOTE – An OAN may or may not extend all the way to the UNI, so that the user-side interface of the OAN does not necessarily coincide with the UNIs of the AN. + +**3.2.4 optical distribution network (ODN)**: A point-to-multipoint optical fibre infrastructure. A *simple* ODN is entirely passive and is represented by a single-rooted point-to-multipoint tree of optical fibres with splitters, combiners, filters, and possibly other passive optical components. A *composite* ODN consists of two or more passive *segments* interconnected by active devices, each of the segments being either an optical trunk line segment or an optical distribution segment. A passive optical distribution segment is a simple ODN itself. Two ODNs with distinct roots can share a common subtree. + +**3.2.5 optical line termination (OLT)**: A network element in an ODN-based optical access network that terminates the root of at least one ODN and provides an OAN SNI. + +**3.2.6 optical network terminal (ONT)**: An ONU supporting a single subscriber. + +**3.2.7 optical network unit (ONU):** A network element in an ODN-based optical access network that terminates a leaf of the ODN and provides an OAN UNI. + +**3.2.8 passive optical network (PON) system:** A combination of network elements in an ODN-based optical access network that includes an OLT and multiple ONUs and implements a particular coordinated suite of physical medium dependent layer, transmission convergence layer, and management protocols. + +*Terms related to optical parameters, power and loss budget* + +**3.2.9 attenuation:** The total relative optical power loss of an optical signal propagating through the ODN. Attenuation is caused by absorption and scattering of light in the fibre (caused by fibre impurities and imperfections, fluctuations of the refractive index, material dispersion), as well as connectors, splices, splitters, wavelength couplers, attenuators, and other passive optical components. + +**3.2.10 differential fibre distance:** The absolute difference between the fibre distances of two particular ONUs connected to the same OLT PON interface. + +**3.2.11 dispersion:** A physical phenomenon comprising the dependence of the phase or group velocity of a light wave in the medium on its propagation characteristics such as optical frequency (wavelength) or polarization mode. + +**3.2.12 dynamic range:** An optical receiver characteristic that represents the difference between the worst-case sensitivity (i.e., maximum over the operating conditions) and the worst-case overload (i.e., minimum over the operating conditions), and is usually expressed as a ratio of the former to the latter. + +**3.2.13 extinction ratio:** With respect to a digital signal generated by an optical source (laser diode), the ratio of the two optical power levels corresponding to the high and low intensities of light emission. + +**3.2.14 fibre distance:** The overall length of fibre (and, if applicable, equivalent fibre runs representing delay-inducing components) between the R/S and S/R reference points. + +**3.2.15 mean optical launch power:** An optical transmitter characteristic expressing the average optical power of an optical signal transmitted into the fibre and carrying a given digital sequence. When specified as a range, the minimum mean launch power provides the power level that the transmitter should guarantee at all times, and the maximum mean launch power provides the power level that the transmitter should never exceed. When applied to burst mode transmission, the term pertains to the time interval during which the transmitter is fully active, and excludes possible starting and ending transient behaviour. + +**3.2.16 nominal line rate:** The total number of bits that can be physically transferred per unit of time over a communication link. Nominal line rate accounts for useful data as well as for all possible protocol overheads and necessarily exceeds the effective data rate on any given protocol level. + +**3.2.17 optical path penalty (OPP):** The apparent reduction of receiver sensitivity due to distortion of the signal waveform during its transmission over the optical path. The optical path penalty accounts for total degradations including the effects of reflections, intersymbol interference, mode partition noise, and laser chirp. + +**3.2.18 optical return loss (ORL):** The total reflection at the source reference point of the optical signal propagation path associated with both discrete reflections at the refractive index discontinuities and distributed backscattering, such as Rayleigh scattering, along the path. Optical return loss is measured as a ratio of the transmitted power to the reflected power. + +**3.2.19 overload:** A receiver parameter that characterizes the maximum value of the average received optical power to achieve the BER at or below the specified reference level. + +**3.2.20 reflectance:** The reflection from any single discrete reflection point in the optical signal propagation path, which is defined to be the ratio of the reflected optical power present at a point, to the optical power incident to that point. + +**3.2.21 sensitivity:** A receiver parameter that characterizes the minimum value of the average received optical power to achieve the BER at or below the specified reference level. + +**3.2.22 tolerance to reflected power (receiver):** A receiver parameter that characterizes the minimum admissible ratio of the average optical input power incident at the receiver to the average reflected power regarded as a noise. + +**3.2.23 tolerance to reflected power (transmitter):** A transmitter parameter that characterizes the maximum admissible ratio of the average reflected optical transmit power incident at the transmitter to the average optical transmit power. + +### *Other terms* + +**3.2.24 activation:** A set of distributed procedures executed by the OLT and the ONUs that allows an inactive ONU to join or resume operations on the PON. The activation process includes three phases: parameter learning, serial number acquisition, and ranging. + +**3.2.25 activation cycle:** A time interval between ONU's consecutive entries into the Initial state (O1). + +**3.2.26 bandwidth allocation:** An upstream transmission opportunity granted by the OLT for a specified time interval to a specified traffic-bearing entity within an ONU. + +**3.2.27 dynamic bandwidth assignment (DBA):** A process by which the OLT distributes upstream PON capacity between the traffic-bearing entities within ONUs, based on dynamic indication of their traffic activity and their configured traffic contracts. + +**3.2.28 effective key length:** The number of randomly generated bits of a cryptographic key. The effective key length may be less than the nominal key length of a particular cryptosystem, if a part of the key is replaced by a well-known bit pattern. + +**3.2.29 equalization delay (EqD):** The requisite delay assigned by the OLT to an individual ONU in order to ensure that the ONU's transmissions are precisely aligned on a common OLT-based upstream frame reference. The ONU's equalization delay is assigned as a result of ranging and is subject to in-service updates in the course of burst arrival phase monitoring. + +**3.2.30 Logical Link Identifier (LLID):** A numeric identifier assigned to a Point-to-Multi Point association between an OLT and ONU established through the Point-to-Point Emulation sublayer. Each Point-to-Multi Point association is assigned a unique LLID. The Point-to-Multi Point association is bound to a logical ONU, where a MAC would observe a private association. + +**3.2.31 ONU management and control interface (OMCI):** An operation and management channel between the OLT and an ONU that is message-based and employs an extendable management information base. + +**3.2.32 physical layer OAM (PLOAM):** An operation and management channel between the OLT and the ONUs that is close to real time and is based on a fixed set of messages. + +**3.2.33 quiet window:** A time interval during which the OLT suppresses all bandwidth allocations to in-service ONUs in order to avoid collisions between their upstream transmissions and the transmissions from ONUs whose burst arrival time is uncertain. The OLT opens a quiet window to allow new ONUs to join the PON and to perform ranging of specific ONUs. + +**3.2.34 ranging:** A procedure of measuring the logical distance between the OLT and any of its subtending ONUs with the objective to determine and assign the appropriate equalization delay, which is necessary to align the ONU's upstream transmissions on a common OLT-based upstream frame reference. Ranging is performed during ONU activation and may be performed while the ONU is in service. + +**3.2.35 requisite delay:** A general term denoting the total extra delay the OLT may require an ONU to apply to the upstream transmission beyond the ONU's regular response time. The purpose of requisite delay is to compensate for variation of propagation and processing delays of individual ONUs, and to avoid or reduce the probability of collisions between upstream transmissions. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|---------|------------------------------------------------------------------------------------| +| AN | Access Network | +| BER | Bit-Error Ratio | +| BW | Bandwidth | +| CAPEX | Capital Expenditure | +| CBU | Cell-site Backhauling Unit | +| CIR | Committed Information Rate | +| CO | Central Office | +| DBA | Dynamic Bandwidth Assignment | +| DSL | Digital Subscriber Line | +| E-LAN | Ethernet LAN service | +| E-Line | Ethernet Line service | +| EPON | Ethernet Passive Optical Network | +| E-Tree | Ethernet Tree Service | +| EVC | Ethernet Virtual Connection | +| FEC | Forward Error Correction | +| FTTCell | Fibre to the Cell site base stations | +| FTTx | Fibre to the x (B – building, business; H – home; C – cabinet, curb, P – premises) | +| G-PON | Gigabit-capable Passive Optical Network | +| ID | Identifier | +| IP | Internet Protocol | +| IPTV | Internet Protocol TV | +| LAN | Local Area Network | +| LLID | Logical Link Identifier | +| MAC | Media Access Control | +| MDU | Multi-Dwelling Unit | +| ME | Managed Entity | +| MIB | Management Information Base | + +| | | +|--------|-------------------------------------------------------------------| +| MPCPDU | Multipoint Control Protocol Data Unit | +| MTU | Multi-Tenant Unit | +| OAM | Operation, Administration and Management | +| OAN | Optical Access Network | +| ODN | Optical Distribution Network | +| OLT | Optical Line Terminal | +| OMCI | Optical network unit Management and Control Interface | +| ONT | Optical Network Terminal | +| ONU | Optical Network Unit | +| OPEX | Operational Expenditure | +| PIR | Peak Information Rate | +| PLOAM | Physical Layer Operations, Administration and Maintenance | +| PM | Performance Monitoring | +| PMD | Physical Medium Dependent (protocol layer) | +| PON | Passive Optical Network | +| QoS | Quality of Service | +| RE | Reach Extender | +| R/S | Reference point at the interface of the ONU to the ODN | +| R'/S' | Reference point at the interface of the Reach extender to the OTL | +| RF | Radio Frequency | +| Rx | Receiver | +| S'/R' | Reference point at the interface of Reach extender to ODN | +| S/R | Reference point at the interface of the OLT to the ODN | +| SNI | Service Node Interface | +| TDMA | Time Division Multiple Access | +| Tx | Transmitter | +| UNI | User Network Interface | +| VLAN | Virtual Local Area Network | +| VoIP | Voice over IP | +| VPN | Virtual Private Network | +| V-Rx | Video Receiver | +| V-Tx | Video Transmitter | +| WBF | Wavelength Blocking Filter | +| WDM | Wavelength Division Multiplexing | +| X/S | Crosstalk-to-Signal ratio | + +# 5 Conventions + +OMCI-EPON has sublayers in both the physical layer and the data link layer for the user data channel and has some clients and functions for the management channel, as shown in Figure 5-1. The sublayers are detailed in [IEEE 802.3], while the clients and functions are detailed in [IEEE 1904.1]. OMCI-EPON replaces the OAM client functions which IEEE 1904.1 Package B defines with OMCI client functions defined by Annex C of [ITU-T G.988]. + +The physical layer consists of the physical medium dependent (PMD) sublayer, physical medium attachment (PMA) sublayer, physical coding (PCS) sublayer and reconciliation sublayer. The medium dependent interface (MDI) connects the optical fibre to PMD. The gigabit medium-independent interface (GMII) and 10 gigabit medium-independent interface (XGMII) are defined between PCS and reconciliation. The PMD sublayer and MDI make reference to clauses 60 and 75 of [IEEE 802.3], and the other sublayers and interfaces refer to clauses 65 and 76 of [IEEE 802.3]. + +The data link layer consists of a media access control (MAC) sublayer, multipoint MAC control (MPMC) sublayer, operations, administration and maintenance (OAM) sublayer and MAC client sublayer. The specifications of the MAC sublayer are the same as gigabit Ethernet except for the preamble, and make reference to clause 56 of [IEEE 802.3]. The MPMC sublayer makes reference to clause 64 of [IEEE 802.3]. The OAM sublayer makes reference to clause 57 of [IEEE 802.3]. MAC client sublayer makes reference to clause 6 of [IEEE 1904.1]. + +The management channel consists of the MAC control client, OAM client and their functions. The MAC control client is a pointer between the MPMC sublayer and its functions, and OAM client is a pointer between the OAM sublayers and OMCI, which corresponds to OAM client functions. These clients and their functions make reference to clause 5 of [IEEE 1904.1]. + +When OMCI is used for EPON ONU management, the same functionality as G-PON PLOAM can be adopted by EPON. The MAC control extension which is defined in Annex 31C of [IEEE 802.3] is a suitable control channel for some requirements such as power management (clause 10.5.4 of [IEEE 1904.1]) and protection (clause 9.3.7 of [IEEE 1904.1]) because of its broadcasting capability and lack of frame rate limitation. The use of the MAC control extension frame payload in OMCI-EPON is described in clause 9.2.4. + +ITU-T Recommendations such as [b-ITU-T G.984.x] and [b-ITU-T G.987.x] separate PON specifications into three documents: PMD layer Recommendation, TC layer Recommendation and OMCI Recommendation. The PMD layer Recommendation corresponds to the specifications of the PMD sublayer and MDI of EPON. The OMCI Recommendation corresponds to the OAM client functions of EPON as described above. The TC layer Recommendation corresponds to the specifications of the other sublayers, clients and functions of EPON. + +![Figure 5-1: Layer structure of OMCI-EPON. The diagram shows the protocol stack for the Data link layer and Physical layer. The Data link layer includes MAC Client, OAM, Multi-Point MAC Control, MAC, and Reconciliation. The Physical layer includes PCS, PMA, and PMD. Management functions (OAM functions, OMCI, MAC control client functions) are shown interacting with the MAC Client and MAC Control Client. The legend indicates ITU-T G.988 (blue), IEEE 1904.1 (black), and IEEE 802.3 (grey).](4801720824e4b5e2361a5564f91cfb70_img.jpg) + +The diagram illustrates the layer structure of OMCI-EPON. It is divided into two main sections: and . The section consists of the Data link layer and the Physical layer. The Data link layer includes the MAC Client, OAM, Multi-Point MAC Control, MAC, and Reconciliation. The Physical layer includes PCS, PMA, and PMD. The Management section includes OAM functions, OMCI, and MAC control client functions. The MAC Client and MAC Control Client are shown interacting with the Management functions. The legend indicates that ITU-T G.988 is represented by a blue box, IEEE 1904.1 by a black box, and IEEE 802.3 by a grey box. + +Figure 5-1: Layer structure of OMCI-EPON. The diagram shows the protocol stack for the Data link layer and Physical layer. The Data link layer includes MAC Client, OAM, Multi-Point MAC Control, MAC, and Reconciliation. The Physical layer includes PCS, PMA, and PMD. Management functions (OAM functions, OMCI, MAC control client functions) are shown interacting with the MAC Client and MAC Control Client. The legend indicates ITU-T G.988 (blue), IEEE 1904.1 (black), and IEEE 802.3 (grey). + +**Figure 5-1 – Layer structure of OMCI-EPON** + +# 6 Architecture of the optical access network + +## 6.1 Network architecture + +The optical section of a local access network system can be either active or passive and its architecture can be either point-to-point or point-to-multipoint. Figure 6-1 shows the architectures considered, such as fibre to the home (FTTH), fibre to the cell sites (FTTCell), fibre to the building/curb (FTTB/C) and fibre to the cabinet (FTTCab). The optical distribution network (ODN) is common to all architectures as shown in Figure 6-1; hence the commonality of this system has the potential to generate large worldwide volumes. + +![Figure 6-1: Network architecture. The diagram shows three network architectures: FTTH/Cell, FTTB/C, and FTTCab. Each architecture consists of a Home network (UNI) connected to an ONU, which is connected to an OLT via a fibre. The FTTB/C and FTTCab architectures include a Network Termination (NT) unit between the Home network and the ONU. The legend defines ONU as Optical network unit, OLT as Optical line termination, NT as Network termination, UNI as User network interface, and SNI as Service node interface.](a26e142d3df5bef41a84a9dd099d7825_img.jpg) + +The diagram illustrates the network architecture for three different FTTx options: FTTH/Cell, FTTB/C, and FTTCab. All three options share a common optical distribution network (ODN) represented by a vertical line on the right. The FTTH/Cell option shows a direct fibre connection from the ONU to the OLT. The FTTB/C and FTTCab options show a copper connection from the NT to the ONU, followed by a fibre connection from the ONU to the OLT. The legend defines the components: ONU (Optical network unit), OLT (Optical line termination), NT (Network termination), UNI (User network interface), and SNI (Service node interface). + +Figure 6-1: Network architecture. The diagram shows three network architectures: FTTH/Cell, FTTB/C, and FTTCab. Each architecture consists of a Home network (UNI) connected to an ONU, which is connected to an OLT via a fibre. The FTTB/C and FTTCab architectures include a Network Termination (NT) unit between the Home network and the ONU. The legend defines ONU as Optical network unit, OLT as Optical line termination, NT as Network termination, UNI as User network interface, and SNI as Service node interface. + +**Figure 6-1 – Network architecture** + +The differences among these FTTx options are mainly due to the different services supported and the different locations of the ONUs rather than the ODN itself, so they can be treated as one in this + +Recommendation. It must be noted that a single OLT optical interface might accommodate a combination of several of the scenarios described in clause 7. + +## 6.2 Reference architecture + +A high level and simple reference architecture of OMCI-EPON is depicted in Figure 6-2 which shows a high level reference architecture very similar to those of [b-ITU-T G.983.x], [b-ITU-T G.984.x] and [b-ITU-T G.987.x]. + +As depicted in Figure 6-2, the ONU provides the UNI towards end users, while the OLT provides the SNI towards core networks. The interface types of UNI/SNI depend on the services offered by the service provider. Typical interfaces are Ethernet interfaces such as 10/100/1000 Base-T. The interface at reference points S/R and R/S at OLT and ONU optical port is a PON-specific interface based on Ethernet frames. + +![Figure 6-2: High level reference architecture of OMCI-EPON. The diagram shows the flow from User side to Network side. On the User side, there are two ONUs and an AF (Access Function). The ONUs connect to a central ODN (Optical Distribution Network) via R/S (Repeater/Splitter) interfaces. The AF connects to one of the ONUs. Above the ONUs, there is a box for 'Access network management functions'. The ODN connects to an OLT (Optical Line Terminal) via another R/S interface. The OLT connects to 'Service node functions' via an SNI (Service Network Interface) at reference point (V). The UNI (User Network Interface) at the AF is labeled as reference point (T). A double-headed arrow at the bottom separates the 'User side' from the 'Network side'.](75f0cb39f1cd165dfe4a6aa6c4d9388d_img.jpg) + +Figure 6-2: High level reference architecture of OMCI-EPON. The diagram shows the flow from User side to Network side. On the User side, there are two ONUs and an AF (Access Function). The ONUs connect to a central ODN (Optical Distribution Network) via R/S (Repeater/Splitter) interfaces. The AF connects to one of the ONUs. Above the ONUs, there is a box for 'Access network management functions'. The ODN connects to an OLT (Optical Line Terminal) via another R/S interface. The OLT connects to 'Service node functions' via an SNI (Service Network Interface) at reference point (V). The UNI (User Network Interface) at the AF is labeled as reference point (T). A double-headed arrow at the bottom separates the 'User side' from the 'Network side'. + +Figure 6-2 – High level reference architecture of OMCI-EPON + +## 6.3 ODN architectures + +OMCI-EPON can use the same ODN architecture as existing PON systems such as B-PON ([b-ITU-T G.983.x]), G-PON ([b-ITU-T G.984.x]) and XG-PON ([b-ITU-T G.987.x]) defined in ITU-T Recommendations, and 1G-EPON and 10G-EPON defined in [IEEE 802.3]. + +The PON systems can be categorized into 1G class PON and 10G class PON by their downstream line rates. 1G class PON includes 1G-EPON described in [IEEE 802.3] and G-PON defined by [b-ITU-T G.984.x]. 10G class PON includes 10G-EPON described in [IEEE 802.3] and XG-PON defined by ITU-T [b-ITU-T G.987.x]. 1G class PON, 10G class PON and video distribution services can co-exist on the same ODN because their downstream signals use different wavelengths. However, TDMA technology is necessary for multiplexing upstream signals of 1G class PON and 10G class PON because some of their wavelengths are the same. + +Figure 6-3 is a reference diagram of the ODN architecture that supports the coexistence of 1G class PON and 10G class PON by OMCI-EPON. Typical line rate of OMCI-EPON is 10G class, but it permits dual rate mode of 10G-EPON and 1G-EPON because clause 75.6 of [IEEE 802.3] defines the dual rate mode. The figure assumes that wavelength blocking filters (WBFs) are used when 10G class EPON, 1G class EPON and video signal are shared within the same ODN. + +Note that this diagram simply provides a reference architecture of the ODN and WBF, and is not intended to limit future designs and implementations. For example, when only 10G-EPON is used, WBF is not necessary. In addition, the coexistence of the 10G-EPON and the 1G-EPON can be achieved by TDMA, but the method of TDMA implementation lies outside the scope of this clause since this would not affect WDM configuration. + +![Figure 6-3: Reference optical architecture for EPON coexistence through splitter. The diagram shows four types of ONUs (ONU(10G-EPON), ONU(10G-EPON+video), ONU(1G-EPON), and ONU(1G-EPON+video)) connected to a central ODN via splitters. The ONUs are connected to a 'Splitter (Second stage, 1 by M)', which is then connected to a 'Splitter (First stage, 2 by N)'. The ODN is connected to an OLT(10G/1G dual rate-EPON) and an OLT(video). The OLT(10G/1G dual rate-EPON) contains a WDM-10/1G-L, Rx, and Tx. The OLT(video) contains a V-Tx. The ONUs contain Logic, Tx, Rx, WBF, WDM, and for the video-enabled ones, V-Rx and WBF-V. Interfaces are labeled IF_10GEPON, IF_1GEPON, and IF_Video.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Figure 6-3: Reference optical architecture for EPON coexistence through splitter. The diagram shows four types of ONUs (ONU(10G-EPON), ONU(10G-EPON+video), ONU(1G-EPON), and ONU(1G-EPON+video)) connected to a central ODN via splitters. The ONUs are connected to a 'Splitter (Second stage, 1 by M)', which is then connected to a 'Splitter (First stage, 2 by N)'. The ODN is connected to an OLT(10G/1G dual rate-EPON) and an OLT(video). The OLT(10G/1G dual rate-EPON) contains a WDM-10/1G-L, Rx, and Tx. The OLT(video) contains a V-Tx. The ONUs contain Logic, Tx, Rx, WBF, WDM, and for the video-enabled ones, V-Rx and WBF-V. Interfaces are labeled IF\_10GEPON, IF\_1GEPON, and IF\_Video. + +G.9801(13)\_F6-3 + +**Figure 6-3 – Reference optical architecture for EPON coexistence through splitter** + +Functions of WBFs and WDMs that enable the 10G-EPON and the 1G-EPON coexistence, shown in Figure 6-3, are listed as follows: + +| | | +|-------------|--------------------------------------------------------------------------------------------------------------------------------------------| +| Tx | Optical transmitter | +| Rx | Optical receiver | +| V-Tx | Video transmitter | +| V-Rx | Video receiver | +| WBF | Wavelength blocking filter for blocking interference signals to Rx. | +| WBF-V | Wavelength blocking filter for blocking interference signals to V-Rx. | +| WDM-10G | WDM filter in the 10G-EPON ONU to combine/isolate the wavelengths of the 10G-EPON upstream and downstream. | +| WDM-10G' | WDM filter in the 10G-EPON ONU to combine/isolate the wavelengths of the 10G-EPON upstream and downstream and isolate the video signal(s). | +| WDM-1G | WDM filter in the 1G-EPON ONU to combine/isolate the wavelengths of the 1G-EPON upstream and downstream. | +| WDM-G' | WDM filter in 1G-EPON ONU to combine/isolate the wavelengths of the 1G-EPON upstream and downstream and isolate the video signal(s). | +| WDM-10G-L | WDM filter in the 10G-EPON OLT to combine/isolate the wavelengths of the 10G-EPON upstream and downstream. | +| WDM-10/1G-L | WDM filter in the 10G/1G dual rate-EPON OLT to combine/isolate the wavelengths of the 10G-EPON and 1G-EPON upstream and downstream. | + +# **7 Scenarios and services** + +## **7.1 Scenarios** + +### **7.1.1 FTTH scenario** + +Within this scenario, the following service categories are considered: + +- Asymmetric broadband services (e.g., IPTV, digital broadcast services, VOD, file download, etc.); +- Symmetric broadband services (e.g., content broadcast, e-mail, file exchange, distance learning, telemedicine, online-game, etc.); +- Voice services – the access network must be able to provide, in a flexible way, narrow-band telephone services. + +### **7.1.2 FTTO scenario** + +Fibre to the office (FTTO) has the same architecture as FTTH, but it addresses business ONUs dedicated to small business customers. Within this scenario, the following service categories are considered: + +- Symmetric broadband services (e.g., group software, content broadcast, e-mail, file exchange, etc.); +- Voice services – the access network must be able to provide, in a flexible way, narrow-band telephone services; +- Private line – the access network must be able to provide, in a flexible way, private line services at several rates. + +### **7.1.3 FTTB scenario** + +The FTTB scenario is divided into two scenarios, one for multi-dwelling units (MDUs) and the other for businesses or mixed environments (MTUs). Each scenario has the following service categories: + +### **7.1.4 FTTB for MDU served residential users** + +Within this scenario, the same service categories as FTTH are considered. + +### **7.1.5 FTTB for MTU-served business users** + +Within this scenario, the same service categories as FTTO are considered. + +### **7.1.6 FTTC and FTTCab scenario** + +Within this scenario, the following service categories have been added to the FTTH scenario: + +- xDSL backhaul. + +### **7.1.7 FTTCell wireless scenario** + +Within this scenario, the ONU is called CBU and will have to offer connectivity to wireless base stations: + +- Symmetric TDM services (e.g., 2G cell site backhaul); +- Symmetric/Asymmetric packet-based broadband services (e.g., 3G/4G cell site backhaul); +- Hot spots. + +### **7.1.8 Environment conditions in outdoor scenarios** + +To support the wide range of scenarios and applications, optical parameters for the OLT and the ONU should be determined to allow outdoor operation. + +## 7.2 Services + +Telecommunication networks are evolving from traditional circuit-based networks to packet-based (i.e., IP/Ethernet-oriented) next-generation networks (NGN), which can effectively provide various services with a common platform [b-ITU-T Y.2201], [b-ITU-T Y.2001]. + +Table 7-1 summarizes examples of PON services for NGN. + +**Table 7-1 – Examples of PON services for NGN** + +| | Service | | Remark | +|-----------------------------------------------------------------|----------------------------|-------------------------|-------------------------------------------------------------------------------------------------| +| 1 | Telephony | VoIP | | +| 2 | TV (real time) | IPTV | To be transported using IP multicast/unicast | +| | | Digital TV broadcasting | Transported using RF-video overlay (see [b-ITU-T G.984.5], [b-ITU-T J.185] and [b-ITU-T J.186]) | +| 3 | High speed Internet access | | UNI is typically Gigabit Ethernet | +| 4 | Mobile backhaul | | Accurate frequency/phase/time synchronization should be supported | +| 5 | L2 VPN services | | Such as Ethernet services, etc. | +| 6 | IP services | | Such as L3 VPN, VoIP, etc. | +| NOTE – See [b-ITU-T G.810], [b-ITU-T G.8261], [b-ITU-T G.8262]. | | | | + +For the business applications, OMCI-EPON should provide access to Ethernet services such as point-to-point, multipoint-to-multipoint and rooted-multipoint Ethernet virtual connection (EVC) services. OMCI-EPON shall also support accurate frequency/phase/time synchronization for the mobile backhaul application. + +As a general requirement, OMCI-EPON needs to support IPv6. + +## 7.3 Maximum/Mean signal transfer delay tolerance + +OMCI-EPON may accommodate services that require a maximum mean signal transfer delay of 1.5 ms for 20 km PONs. Specifically, OMCI-EPON systems may have a maximum mean signal transfer delay time of less than 1.5 ms between T-V (or (a)-V, depending on operator's preference). See clause 12 of [b-ITU-T G.982]. Delays introduced by the adaptation functions such as circuit emulation are not included in this value. + +Although a section of the delay measurement is T-V for FTTH system or (a)-V for the other application in [b-ITU-T G.982], in OMCI-EPON systems the reference points are not restricted by the system configuration. + +## 7.4 Frame length + +OMCI-EPON technology shall support Ethernet frames having a maximum length of 2000 bytes. + +## 7.5 Synchronization features and quality + +Network operators are motivated to leverage the OMCI-EPON infrastructure and systems to deliver high bandwidth to mobile cell sites optionally. This requires accurate synchronization and timing delivery to the cell sites. Typically, T1 or E1 interfaces have been used for backhaul and these provide the necessary synchronization and timing references. However, driven by the popularity of 3G/4G wireless, it is increasingly important to provide accurate synchronization and timing over packet interfaces (e.g., Ethernet), especially to the cell sites where no T1/E1 interface is available. + +OMCI-EPON OLTs for this application may be able to receive a high-quality timing clock as well as to serve as a master timing source for the ONUs. The ONUs may be able to distribute accurate timing/synchronization to the cell sites to meet the cell site frequency/phase/time synchronization requirements. + +For this purpose, OMCI-EPON may be required to transfer accurate phase/time information between OLT and ONUs taking into account the propagation delay and the processing delay between them. Additional inaccuracy incurred in the PON section should be much less than the reference accuracy to leave a margin for other network sections in order to apply the optional function. [b-ITU-T G.8261] and [b-ITU-T G.8262] contain synchronization requirements for different wireless technologies. + +The mechanisms, for instance as specified in [b-ITU-T G.8261] and [b-ITU-T G.8262], for distributing accurate timing to the 3G/4G cell sites are for further study depending on the performance and economics. In view of the extra complexity in delivering timing to applications such as mobile backhaul, the additional functionality might be limited to specific "CBU" ONUs. + +## **7.6 QoS and traffic management** + +OMCI-EPON may be capable of supporting multiple existing and emerging services across multiple market segments, such as consumer, business and mobile backhaul. OMCI-EPON may provide simultaneous access to packet-based services, such as high speed Internet access, IPTV and VoIP. In addition, OMCI-EPON may provide access to carrier-grade Metro Ethernet services, such as point-to-point, multipoint-to-multipoint and rooted-multipoint EVC services for business customers. These varieties of services present a broad range of QoS characteristics, which demand systems that provide appropriate traffic management mechanisms. + +To provide access to various packet-based services, such as IPTV, VoIP, L2/L3 VPNs and high speed Internet access, OMCI-EPON may provide at least 4 classes of services to map UNI flows. It is desirable for OMCI-EPON to provide at least 6 classes of services to map UNI flows. OMCI-EPON may also support drop precedence within at least 2 traffic classes. + +In addition to the priority-based class of services, OMCI-EPON ONU may support rate-controlled services (e.g., CIR/PIR) with policing and shaping function in addition to the priority-based traffic management, for instance for business applications and mobile backhaul. Business customer ONUs may also support industry specifications at UNI ports. + +OMCI-EPON may support any mix of residential, business and mobile backhaul traffic within the same PON as shown in clause 7.1. It may also support a mix of consumer and business users within a multiple subscriber ONU. OMCI-EPON may support a mix of rate-based (including CIR/PIR provisioning, policing, shaping, etc.) and priority-based traffic management within the same PON and same ONU. + +OMCI-EPON OLT must support Transparent VLAN mode, Tagging VLAN mode and Translation VLAN mode. Furthermore OMCI-EPON ONU must support Transparent VLAN mode, Tagging VLAN mode and ToS/CoS Conversion VLAN mode. + +# **8 Requirements** + +## **8.1 Physical layer and MAC layer requirements** + +Physical layer specifications and MAC layer specifications of OMCI-EPON are the IEEE 802.3 standard. + +## **8.2 System level requirements** + +System level requirements and specifications are based on the IEEE 1904.1 standard, with some additional requirements as below. + +### **8.2.1 Power saving and energy efficiency** + +See clause 10.5.4 of [IEEE 1904.1]. + +### **8.2.2 Authentication/Identification/Encryption** + +See clause 11.3.4 of [IEEE 1904.1]. + +### **8.2.3 Dynamic bandwidth assignment (DBA)** + +OMCI-EPON OLT may support DBA for the efficient sharing of upstream bandwidth among the connected ONUs and the traffic-bearing entities within the individual ONUs based on the dynamic indication of their activity. + +The OLT may support any of the dynamic activity indication methods or a combination thereof. It is outside the scope of the requirement specification to define how the OLT utilizes the obtained dynamic activity indication information, or how the OLT upstream scheduler is implemented. + +### **8.2.4 Eye safety** + +Given the high launched optical powers that can be injected into the fibre in OMCI-EPONs, both at the OLT level and the RE level, all necessary mechanisms must be provided to ensure that end users unaware of the risks suffer no eye damage, especially if fibre is terminated inside the home. OMCI-EPON elements need to conform to the following specific classes defined in the IEEE 802.3 standard, respectively: + +- Class 1 for OLT +- Class 1 for ONU + +## **8.3 Operational requirements** + +Operational requirements and specifications are defined in [IEEE 1904.1] Package B. Additional requirements are described as below. + +### **8.3.1 ONU management** + +#### **8.3.1.1 OMCI managed ONU** + +It is necessary from the network operation perspective to manage OMCI-EPON, i.e., an OLT together with its ONUs, as a single entity, with ONUs being managed via OLTs, wherever possible. Therefore, OMCI-EPON shall support full PON real time management through OMCI for EPON defined by Annex C of [ITU-T G.988]. + +#### **8.3.1.2 Dual managed ONU** + +OMCI-EPON should support collaborative ONU management partition between EPON OMCI and remote configuration mechanisms. + +### **8.3.2 PON supervision** + +While it is most important to minimize CAPEX in the initial stage of FTTH deployment, it is getting more important to reduce OPEX as well as to optimize the balance between CAPEX and OPEX according to the full deployment of FTTH. The goal of PON supervision is to reduce the OPEX of PON systems, without significantly increasing the CAPEX by including as much test and diagnostic capability as possible without compromising the available bandwidth for services. Test and diagnostics must not impact the service. + +The ability to reliably differentiate between optical and electrical faults and establish if the faults are in the ODN or in the electronics is a key operator requirement. Inference can usually be made from the presence (i.e., power or equipment failure) or absence (i.e., fibre failure) of the ONU Dying Gasp Alarm. Several key points for the supervision of OMCI-EPON can be summarized as follows: + +- Transceiver status monitoring: + +See clause 9.1.5 of [IEEE 1904.1]. + +- ODN monitoring/checking: + +Monitoring and on-demand checking the condition of ODN independently from a PON system is important to differentiate ODN failures from device failures. It is desirable that such monitoring and checking are available regardless of whether the ONU is in service or even not connected. An Optical Time Domain Reflectometer (OTDR) is a powerful tool for diagnosing such faults in the ODN, and a power meter and light source can be used to aid the process. Several demarcation devices are under research for further improving the ODN monitoring and checking. + +OMCI-EPON systems would benefit from the ability to automatically and autonomously detect and locate ODN faults. This is especially critical for the feeder section between the serving CO and the first-stage splitter, the length of which can be up to 60 km if RE is used. + +- End-to-end performance monitoring up to the Ethernet layer: + +End-to-end performance monitoring enables operators to diagnose and identify where customer traffic may have been dropped or throttled. Higher layer tools, such as Ethernet performance monitoring, need to support the capability of monitoring and verification of ingress and egress traffic flows in PON network elements. + +- Proactive versus reactive repair: + +PON systems with their monitoring and control systems will allow operators to make decisions regarding the utilization of proactive or reactive fault repairs in most fault cases. It is of course up to the operators to decide on how to use PON status reports. + +## **8.4 Resilience and protection on ODN** + +See clause 9.3.7 of [IEEE 1904.1]. + +# **9 Optical network requirements** + +## **9.1 Physical medium dependent (PMD) sublayer** + +This clause addresses physical media dependent layer requirements for OMCI-EPON. OMCI-EPON shall support the parameters specified in the following clause of [IEEE 802.3]. + +For 1G link, see clause 60 of [IEEE 802.3]. + +For 10G link, see clause 75 of [IEEE 802.3]. + +## **9.2 Media access control (MAC), extensions of the reconciliation sublayer (RS) and physical coding sublayer (PCS)/physical media attachment (PMA)** + +This clause addresses data link layer requirements and physical layer requirements except on the PMD layer for OMCI-EPON. + +### **9.2.1 Extensions of the reconciliation sublayer (RS) and physical coding sublayer (PCS)/physical media attachment (PMA)** + +This clause addresses the functions that modify the bit stream modulating the optical transmitter with the goal of improving the detection, reception and delineation properties of the signal transmitted over the optical medium. Forward error correction and line coding functionalities are included in this clause. OMCI-EPON shall comply with the specifications described in the following clauses of [IEEE 802.3]. + +For 1G link, see clause 65 of [IEEE 802.3]. + +For 10G link, see clause 76 of [IEEE 802.3]. + +### **9.2.2 Media access control (MAC) frame and packet specifications** + +This clause addresses the frame format of data link layer for OMCI-EPON. OMCI-EPON shall comply with the specifications described in the following clause of [IEEE 802.3]. + +See clause 3 of [IEEE 802.3]. + +### **9.2.3 Multipoint MAC control** + +This clause addresses the mechanism and control protocols required in order to reconcile the point to multi-point topology into the Ethernet framework. OMCI-EPON shall comply with the specifications described in the following clause of [IEEE 802.3]. + +For 1G link, see clause 64 of [IEEE 802.3]. + +For 10G link, see clause 77 of [IEEE 802.3]. + +### **9.2.4 MAC control extension** + +As OMCI is adopted for EPON ONU management, the same functionality of PLOAM can be adopted by the EPON system for supporting functionalities such as protection switching and ONU power saving. For such functionalities, MAC control extension, which is defined in Annex 31C of [IEEE 802.3], is the suitable control channel because of its broadcast capability and lack of frame rate limitation. Definition of the MAC control extension frame payload is reserved for ITU-T. This Recommendation provides a detailed definition of the MAC control extension frame. + +Specifications for the MAC control-frame structure and the various messages for the optical link protection function are found in clause 9.3.5 of [IEEE 1904.1]. + +Specifications for the MAC control-frame structure and the various messages for the ONU power management function are found in clause 10.5.4 of [IEEE 1904.1]. + +### **9.2.5 Resource allocation and Quality of Service** + +This clause addresses the REPORT MPCPDU format and Quality of Service mechanisms. OMCI-EPON shall support the requirements described in the following clause of [IEEE 1904.1]. + +See clause 8.4.3 of [IEEE 1904.1]. + +In EPON, REPORT MPCPDU format is configurable. The OLT configures the REPORT MPCPDU with related attributes in ANI-E ME in [ITU-T G.988]. + +### **9.2.6 Performance monitoring, supervision and defects** + +This clause addresses the mechanisms to detect link failure and monitor the health and performance of links. + +#### **9.2.6.1 Performance monitoring** + +OMCI-EPON shall support the event monitoring functions described in the following clause of [IEEE 1904.1]. + +See clause 9.2.7 of [IEEE 1904.1]. + +#### **9.2.6.2 Defects** + +See clauses 9.2.6 and 9.2.8 of [IEEE 1904.1]. + +### **9.2.7 Security** + +This clause addresses the encryption mechanism and the authentication mechanism for OMCI-EPON. OMCI-EPON shall support the requirements described in the following clauses in [IEEE 1904.1]. + +For encryption mechanism, see clause 11.2.3 of [IEEE 1904.1]. + +For authentication mechanism, see clause 11.3.4 of [IEEE 1904.1]. + +In [IEEE 1904.1] Package B, encryption capability is mandatory for 10G-EPON. The OLT enables or disables encryption function with the encryption capability and configuration attribute in ANI-E ME in [ITU-T G.988]. + +### **9.2.8 ONU power management** + +This clause addresses the ONU power management mechanism for OMCI-EPON. OMCI-EPON shall optionally support the requirements described in the following clauses in [IEEE 1904.1]. + +For signalling protocol, see clause 10.5.4 of [IEEE 1904.1]. + +The OLT configures parameters for ONU power management with ONU dynamic power management control ME in [ITU-T G.988]. + +### **9.2.9 Optical link protection** + +This clause addresses the optical link protection mechanism for OMCI-EPON. That protection scheme is the same configuration as type-B protection in [ITU-T G.984.1]. OMCI-EPON shall optionally support the requirements described in the following clauses in [IEEE 1904.1]. + +For signalling protocol, see clause 9.3.7 of [IEEE 1904.1]. + +In EPON, a timer for the type-B protection is defined as HoldOver timer. It is similar to timer TO2 in G-PON/XG-PON, and its value is configurable. Triggers for state transition of the ONU to the HoldOver state are defined as LoS\_Optical and LoS\_MAC. Durations for these parameters are configurable. The OLT configures the parameters for the optical link protection with related attributes of ANI-E ME in [ITU-T G.988]. + +### **9.2.10 Connectivity configurations** + +This clause addresses the VLAN configurations and multicast configurations for OMCI-EPON. OMCI-EPON shall support the requirements in the following clause in [IEEE 1904.1]. + +For VLAN configurations, see clauses 7.2.2.1.1, 7.2.2.1.3 and 7.2.2.1.5 of [IEEE 1904.1]. + +For multicast configurations, see clause 7.4.2 of [IEEE 1904.1]. + +The OLT configures parameters for multicast configurations with L2 multicast GEM interworking termination point ME in [ITU-T G.988]. + +## **9.3 OMCI-EPON management** + +See Annex C of [ITU-T G.988]. + +# Bibliography + +- [b-ITU-T G.810] Recommendation ITU-T G.810 (1996), *Definitions and terminology for synchronization networks.* +- [b-ITU-T G.982] Recommendation ITU-T G.982 (1996), *Optical access networks to support services up to the ISDN primary rate or equivalent bit rates.* +- [b-ITU-T G.983.x] Recommendation ITU-T G.983.x-series, *Broadband optical access systems.* +- [b-ITU-T G.983.1] Recommendation ITU-T G.983.1 (2005), *Broadband optical access systems based on Passive Optical Networks (PON).* +- [b-ITU-T G.983.2] Recommendation ITU-T G.983.2 (2005), *ONT management and control interface specification for B-PON.* +- [b-ITU-T G.983.3] Recommendation ITU-T G.983.3 (2001), *A broadband optical access system with increased service capability by wavelength allocation.* +- [b-ITU-T G.984.x] Recommendation ITU-T G.984.x-series, *Gigabit-capable passive optical networks (GPON).* +- [b-ITU-T G.984.2] Recommendation ITU-T G.984.2 (2003), *Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification.* +- [b-ITU-T G.984.3] Recommendation ITU-T G.984.3 (2008), *Gigabit-capable Passive Optical Networks (G-PON): Transmission convergence layer specification.* +- [b-ITU-T G.984.5] Recommendation ITU-T G.984.5 (2007), *Gigabit-capable Passive Optical Networks (G-PON): Enhancement band.* +- [b-ITU-T G.987.x] Recommendation ITU-T G.987.x-series (2012), *10-Gigabit-capable passive optical networks (XG-PON).* +- [b-ITU-T G.987] Recommendation ITU-T G.987 (2012), *10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations and acronyms.* +- [b-ITU-T G.987.1] Recommendation ITU-T G.987.1 (2010), *10-Gigabit-capable passive optical networks (XG-PON): General requirements.* +- [b-ITU-T G.987.2] Recommendation ITU-T G.987.2 (2010), *10-Gigabit-capable passive optical networks (XG-PON): Physical media dependent (PMD) layer specification.* +- [b-ITU-T G.987.3] Recommendation ITU-T G.987.3 (2010), *10-Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification.* +- [b-ITU-T G.8261] Recommendation ITU-T G.8261/Y.1361 (2008), *Timing and synchronization aspects in packet networks.* +- [b-ITU-T G.8262] Recommendation ITU-T G.8262/Y.1362 (2010), *Timing characteristics of a synchronous Ethernet equipment slave clock.* +- [b-ITU-T I.112] Recommendation ITU-T I.112 (1993), *Vocabulary of terms for ISDNs.* + +- [b-ITU-T J.185] Recommendation ITU-T J.185 (2012), *Transmission equipment for transferring multi-channel television signals over optical access networks by frequency modulation conversion.* +- [b-ITU-T J.186] Recommendation ITU-T J.186 (2008), *Transmission equipment for multi-channel television signals over optical access networks by sub-carrier multiplexing (SCM).* +- [b-ITU-T Y.2001] Recommendation ITU-T Y.2001 (2004), *General overview of NGN.* +- [b-ITU-T Y.2201] Recommendation ITU-T Y.2201 (2009), *Requirements and capabilities for ITU-T NGN.* +- [b-BBF TR-200] BBF TR-200 (2011), *Using EPON in the Context of TR-101.* +- [b-MEF 6.1] MEF Technical Specification MEF 6.1 (2008), *Ethernet Services Definitions – Phase 2.* +- [b-MEF 10.1] MEF Technical Specification MEF 10.1 (2006), *Ethernet Services Attributes Phase 2.* + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph 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CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9804.3 + +# 50-Gigabit-capable passive optical networks (50G-PON): Physical media dependent (PMD) layer specification + +## Summary + +Recommendation ITU-T G.9804.3 describes a 50-Gigabit-capable passive optical network (50G-PON) system in an optical access network for residential, business, mobile backhaul and other applications. This system operates over a point-to-multipoint optical access infrastructure at the nominal line rate of 50 Gbit/s in the downstream direction. In the upstream direction, 12.5 Gbit/s and 25 Gbit/s nominal line rates are currently defined; a 50 Gbit/s nominal line rate is for future study. This Recommendation contains the references, the common definitions, acronyms, abbreviations and the specifications of the physical media dependent layer of the 50G-PON system. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.9804.3 | 2021-09-06 | 15 | 11.1002/1000/14714 | + +## Keywords + +50-Gigabit-capable, 50G-PON, asymmetric line rates, coexistence, multi-PON module (MPM), passive optical network (PON), physical medium dependent (PMD), transmitter and dispersion eye closure (TDEC). + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2021 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-----------------------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 4 | +| 4 Abbreviations and acronyms ..... | 6 | +| 5 Conventions ..... | 7 | +| 6 Architecture of the optical access network..... | 7 | +| 6.1 Classes for optical path loss ..... | 8 | +| 6.2 Categories for fibre differential distance..... | 9 | +| 7 This clause is intentionally left blank ..... | 9 | +| 8 This clause is intentionally left blank ..... | 9 | +| 9 Optical network requirements..... | 9 | +| 9.1 Layered structure of optical network..... | 9 | +| 9.2 PMD layer requirements for the 50G-PON ..... | 10 | +| 10 X/S tolerance of 50G-PON ONU and OLT..... | 30 | +| 10.1 Versatile WDM configuration..... | 31 | +| 11 Upstream physical layer overhead..... | 33 | +| Appendix I – Relationship between OMA, penalty, extinction ratio and average power ..... | 34 | +| Appendix II – Physical layer measurements required to support optical layer supervision.... | 36 | +| Appendix III – Allocation of the physical layer overhead time..... | 37 | +| Appendix IV – Relationship among optical interface parameters for 49.7664 Gbit/s
downstream..... | 40 | +| Bibliography..... | 41 | + + + +## Recommendation ITU-T G.9804.3 + +# 50-Gigabit-capable passive optical networks (50G-PON): Physical media dependent (PMD) layer specification + +# 1 Scope + +This Recommendation pertains to flexible access networks using optical fibre technology. The focus is primarily on a network supporting services with bandwidth requirements ranging from those of voice traffic to data services running at up to 50 Gbit/s. Also included are broadcast services. + +This Recommendation describes the characteristics of the physical medium dependent (PMD) layer of an optical access network (OAN) with the capability of transporting various services between the user-network interface and the service node interface. + +The OAN considered in this Recommendation enables the network operator to provide a flexible upgrade to meet future customer requirements, in particular, in the area of the optical distribution network (ODN). The ODN considered is based on a point-to-multipoint tree and branch option. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.652] Recommendation ITU-T G.652 (2005), *Characteristics of a single-mode optical fibre cable*. +- [ITU-T G.657] Recommendation ITU-T G.657 (2016), *Characteristics of a bending loss insensitive single mode optical fibre and cable for the access network*. +- [ITU-T G.902] Recommendation ITU-T G.902 (1995): *Framework Recommendation on functional access networks (AN) – Architecture and functions, access types, management and service node aspects*. +- [ITU-T G.959.1] Recommendation ITU-T G.959.1 (2018), *Optical transport network physical layer interfaces*. +- [ITU-T G.982] Recommendation ITU-T G.982 (1996), *Optical access networks to support services up to the ISDN primary rate or equivalent bit rates*. +- [ITU-T G.983.1] Recommendation ITU-T G.983.1 (2005), *Broadband optical access systems based on Passive Optical Networks (PON)*. +- [ITU-T G.984.2] Recommendation ITU-T G.984.2 (2019), *Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification*. +- [ITU-T G.984.5] Recommendation ITU-T G.984.5 (2014) Amendment 2 (10/20), *Gigabit-capable passive optical networks (G-PON): Enhancement band*. +- [ITU-T G.987] Recommendation ITU-T G.987 (2012), *10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations and acronyms*. + +| | | +|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T G.989] | Recommendation ITU-T G.989 (2015), 40-Gigabit-capable passive optical networks (NG-PON2): Definitions, abbreviations and acronyms. | +| [ITU-T G.989.2] | Recommendation ITU-T G.989.2 (2020), 40-Gigabit-capable passive optical networks 2 (NG-PON2): Physical media dependent (PMD) layer specification - Amendment 1. | +| [ITU-T G.9804.1] | Recommendation ITU-T G.9804.1 (2019), Higher speed passive optical networks – Requirements. | +| [ITU-T G.9804.2] | Recommendation ITU-T G.9804.2 (2021), Higher speed passive optical networks: Common transmission convergence layer specification. | +| [ITU-T G.9807.1] | Recommendation ITU-T G.9807.1 (2016) Amendment 2 (10/20), 10-Gigabit-capable symmetric passive optical network (XGS-PON). | +| [ITU-T L.313] | Recommendation ITU-T L.313 (2016), Optical fibre cable maintenance criteria for in-service fibre testing in access networks. | +| [IEEE 802.3] | IEEE 802.3-2018, IEEE Standard for Ethernet. | + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendations uses the following terms defined elsewhere: + +**3.1.1 10-Gigabit-capable PON encapsulation method (XGEM)** [ITU-T G.9804.1]: A data frame transport scheme that is connection-oriented and that supports fragmentation of user data frames into variable sized transmission fragments. + +**3.1.2 10-Gigabit-capable passive optical network (XG(S)-PON)** [ITU-T G.9804.1]: A PON system supporting nominal transmission rates on the order of 10 Gbit/s in at least one direction, and implementing the suite of protocols specified in ITU-T G.987.x series of Recommendations (XG-PON) or in the ITU-T G.9807.1 (XGS-PON), as the realization of next generation passive optical network 1 (NG-PON1). + +**3.1.3 attenuation:** See optical path loss. + +**3.1.4 coexistence element** [ITU-T G.9804.1]: A bidirectional functional element used to connect passive optical network (PON) systems defined in different Recommendation series to the same optical distribution network (ODN). + +**3.1.5 consecutive identical digit (CID) immunity** [ITU-T G.9807.1]: The longest continuous sequence of identical bits that can be present in a digital signal without causing degradation such that the system specifications are no longer met. + +**3.1.6 differential fibre distance dynamic range** [ITU-T G.9804.1]: An optical receiver characteristic that is equal to the ratio of the receiver overload to the receiver sensitivity. + +**3.1.7 dispersion** [ITU-T G.9804.1]: A physical phenomenon comprising the dependence of the phase or group velocity of a light wave in the medium on its propagation characteristics such as optical frequency (wavelength) or polarization mode. + +**3.1.8 dynamic bandwidth assignment (DBA)** [ITU-T G.9804.1]: A process by which the optical line terminal (OLT) distributes upstream passive optical network (PON) capacity between the traffic-bearing entities within optical network units (ONUs), based on the dynamic indication of their traffic activity and their configured traffic contracts. + +**3.1.9 extinction ratio** [ITU-T G.9804.1]: With respect to a digital On-Off keying signal generated by an optical transmitter, the ratio of the average optical power level at the centre of the binary digit corresponding to the high intensity of light to the average optical power level at the centre of a binary + +digit corresponding to the low intensity of light. For the burst mode signal, averaging is performed over the time periods when the transmitter is enabled but excluding the associated transient times (see clause 5.13 in [ITU-T G.9804.1]). For the continuous mode signal, averaging is performed over the entire signal string. + +**3.1.10 fibre differential distance** [ITU-T G.9804.1]: The absolute difference between the fibre distances of any two given paths between the R/S and S/R [or S/Rm] reference points in the same ODN. + +**3.1.11 gigabit-capable passive optical network (G-PON)** [ITU-T G.9804.1]: A PON system supporting transmission rates in excess of 1 Gbit/s in at least one direction and implementing the suite of protocols specified in the ITU-T G.984.x series of Recommendations. + +**3.1.12 jitter (timing jitter)** [b-ITU-T G.810]: The short-term variations of the significant instants of a timing signal from their ideal positions in time (where short-term implies that these variations are of frequency greater than or equal to 10 Hz). + +**3.1.13 line code** [ITU-T G.9804.1]: In the higher speed PON (HSP) context, a code that transforms a binary digital signal into an amplitude- and time-discrete waveform for transmission over a physical channel. + +**3.1.14 nominal line rate** [ITU-T G.9804.1]: The total number of bits that can be physically transferred per unit of time over a communication link. Nominal line rate accounts for useful data as well as for all possible protocol overheads and necessarily exceeds the effective data rate on any given protocol level. + +**3.1.15 ODN fibre distance class** [ITU-T G.9807.1]: A categorization of an optical distribution network (ODN) based on the predefined values of minimum and maximum fibre distance between the S/R [or S/Rm] and any of R/S reference points. + +**3.1.16 ODN optical path loss class (ODN class)** [ITU-T G.9804.1]: A categorization of an optical distribution network (ODN) based on the predefined values of minimum and maximum optical path loss over all possible paths between the S/R [or S/Rm] and any of the R/S reference points and over all possible operating wavelengths of a specific PON system. + +**3.1.17 optical access network (OAN)** [ITU-T G.987]: A part of an access network whose network elements are interconnected by optical communication channels. + +NOTE – An OAN may or may not extend all the way to the UNI, so that the user-side interface of the OAN does not necessarily coincide with the UNIs of the AN. + +**3.1.18 optical distribution network (ODN)** [ITU-T G.9804.1]: A point-to-multipoint optical fibre infrastructure. A simple ODN is entirely passive and is represented by a single-rooted point-to-multipoint tree of optical fibres with splitters, combiners, filters and possibly other passive optical components. A composite ODN consists of two or more passive segments interconnected by active devices, each of the segments being either an optical trunk line segment or an optical distribution segment. A passive optical distribution segment is a simple ODN itself. Two ODNs with distinct roots can share a common subtree. + +**3.1.19 optical distribution segment (ODS)** [ITU-T G.9804.1]: A simple optical distribution network (ODN), that is, a point-to-multipoint optical fibre infrastructure that is entirely passive and is represented by a single-rooted tree of optical fibres with splitters, combiners, filters, and possibly other passive optical components. + +**3.1.20 optical line termination (OLT)** [ITU-T G.9804.1]: A network element in an ODN-based optical access network that terminates the root of at least one optical distribution network (ODN) and provides an optical access network (OAN) service node interface (SNI). + +**3.1.21 optical modulation amplitude (OMA)** [ITU-T G.9807.1]: The absolute difference between the optical power of a logic one level and the optical power of a logic zero level. See Appendix I of [ITU-T G.9807.1] for more details on OMA. + +**3.1.22 optical network unit (ONU)** [ITU-T G.9804.1]: A network element in an ODN-based optical access network that terminates a leaf of the optical distribution network (ODN) and provides an optical access network (OAN) user-network interface (UNI). + +**3.1.23 optical path loss:** The reduction in the optical power of light having traversed the ODN expressed as a ratio in decibel units. This loss may be caused by the fibre, connectors, splices, splitters, wavelength couplers, attenuators, and other passive optical components. + +**3.1.24 optical path penalty (OPP)** [ITU-T G.9804.1]: The apparent degradation of receiver sensitivity due to impairments from fibre transmission and apparent increase in ODN loss due to Raman depletion. The optical path penalty accounts for the effects of reflections, inter-symbol interference, mode partition noise, fibre dispersion, and fibre non-linearities. + +**3.1.25 optical return loss (ORL)** [ITU-T G.9804.1]: The total reflection at the source reference point of the optical signal propagation path, measured as a ratio of the transmitted optical power to the reflected optical power. + +**3.1.26 passive optical network (PON) system** [ITU-T G.9804.1]: A combination of network elements in an ODN-based optical access network that includes an optical trunk line and one or more optical network units and implements a particular coordinated suite of physical medium dependent layer, transmission convergence layer, and management protocols. + +**3.1.27 reflectance** [ITU-T G.9804.1]: The reflection from any single discrete reflection point in the optical signal propagation path, which is defined to be the ratio of the reflected optical power present at a point, to the optical power incident to that point. + +**3.1.28 side mode suppression ratio** [ITU-T G.9804.1]: The ratio of the power of the largest peak of the transmitter spectrum to that of the second largest peak. The second largest peak may be next to the main peak, or far removed from it. Within this definition, spectral peaks that are separated from the largest peak by the clock frequency are not considered to be side modes. + +**3.1.29 tolerance to reflected optical power** [ITU-T G.9804.1]: A transmitter parameter that characterizes the maximum admissible ratio of the average reflected optical transmit power incident at the transmitter to the average optical transmit power. + +**3.1.30 transmission container (T-CONT)** [ITU-T G.9804.1]: A traffic-bearing object within an optical network unit (ONU) that represents a group of logical connections, is managed via the ONU management and control channel (OMCC), and, through its TC layer Alloc-ID, is treated as a single entity for the purpose of upstream bandwidth assignment on the passive optical network (PON). + +**3.1.31 XG-PON** [ITU-T G.9804.1]: Asymmetric 10-Gigabit Passive Optical Network. + +**3.1.32 XGS-PON** [ITU-T G.9804.1]: A variant of 10-Gigabit-capable passive optical network system that operates at a nominal line rate of 10 Gbit/s downstream and upstream, implementing the suite of protocols specified in [ITU-T G.9807.1]. + +## **3.2 Terms defined in this Recommendation** + +This Recommendation defines the following terms: + +**3.2.1 differential optical path loss:** The absolute difference between the optical losses, expressed in decibel units, of any two given paths between the R/S and S/R for channel group (S/R-CG) reference points in the same optical distribution network (ODN). + +NOTE – Definition based on the one provided in [ITU-T G.9804.1]. + +**3.2.2 fibre distance:** The overall length of fibre (and, if applicable, equivalent fibre runs representing delay-inducing components) between the R/S and S/R for channel group (S/R-CG) reference points. + +NOTE – Definition based on the one provided in [ITU-T G.9804.1]. + +**3.2.3 mask of transmitter eye diagram:** A general method of transmitter pulse shape characterisation that allows the combined specification of rise time, fall time, pulse overshoot/undershoot, ringing and jitter to ensure satisfactory operation with a compliant receiver. Transmitter mask compliance is required at the appropriate reference point (S/R for channel group (S/R-CG) for downstream, R/S for upstream). + +NOTE – Definition based on the one provided in [ITU-T G.9804.1]. + +**3.2.4 mean launch optical power:** An optical transmitter characteristic expressing the average optical power of an optical signal transmitted into the fibre and carrying a given digital sequence, referring to the optical power of an individual wavelength channel at the appropriate reference point (S/R or S/Rm for downstream direction, R/S for upstream direction). When specified as a range, the minimum mean launch optical power provides the power level that the transmitter should guarantee at all times, and the maximum mean launch optical power provides the power level that the transmitter should never exceed. When applied to burst mode transmission, the term pertains to the time interval during which the transmitter is enabled and excludes possible starting and ending transient behaviour. + +NOTE – Definition based on the one provided in [ITU-T G.9804.1]. + +**3.2.5 overload:** A receiver parameter equal to the maximum average received optical power that produces the specified bit error ratio (BER) reference level, referring to the optical power of an individual wavelength channel at the appropriate reference point (S/R-CG for upstream direction, R/S for downstream direction) measured with the worst-case signal, but without the optical path impairments. + +NOTE – Definition based on the one provided in [ITU-T G.9804.1]. + +**3.2.6 sensitivity:** A receiver parameter equal to the minimum average received optical power that produces the specified bit error ratio (BER) reference level, referring to the optical power of an individual wavelength channel at the appropriate reference point (S/R-CG for upstream direction, R/S for downstream direction) measured with the worst-case signal, but without the optical path impairments. + +NOTE – Definition based on the one provided in [ITU-T G.9804.1]. + +**3.2.7 transmitter and dispersion eye closure (TDEC):** TDEC is an optical transmitter quality metric derived using histograms extracted from the eye diagram. The optical transmitter is measured using a waveform monitoring device in a set-up that emulates the worst-case channel, including fibre, reference receiver and equalizer. + +**3.2.8 transmitter disable time:** For a burst-mode transmitter, the allocated transient time on de-assertion of the TxEnable signal, measured in bit periods with respect to the transmitter nominal line rate. + +NOTE – This definition is the same as that for transmitter disable transient time in [ITU-T G.9804.1]. + +**3.2.9 transmitter enable time:** For a burst-mode transmitter, the allocated transient time on assertion of the TxEnable signal, measured in bit periods with respect to the transmitter nominal line rate. + +NOTE – This definition is the same as that for transmitter enable transient time in [ITU-T G.9804.1]. + +**3.2.10 transmitter eye closure (TEC):** TEC is an optical transmitter quality metric derived using histograms extracted from the eye diagram. The optical transmitter is measured using the same method as TDEC but without the optical path impairments. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-----------------|---------------------------------------------------------------------| +| APD | Avalanche Photodiode | +| BER | Bit Error Ratio | +| CE x | Coexistence Element Type x (x = 1, 2, etc.) | +| CID | Consecutive Identical Digits | +| CRU | Clock Recovery Unit | +| DBA | Dynamic Bandwidth Assignment | +| DC | Direct Current | +| DD | Differential Distance | +| ER | Extinction Ratio | +| FEC | Forward Error Correction | +| FFE | Feedforward Equalizer | +| FFS | For Further Study | +| HSP | Higher Speed PON | +| LDPC | Low-density Parity Check | +| MPM | Multi-PON Module | +| NRZ | Non-Return to Zero | +| OAM | Operation, Administration and Maintenance | +| OAN | Optical Access Network | +| ODN | Optical Distribution Network | +| ODS | Optical Distribution Segment | +| O/E | Optical-to-electrical | +| OLT | Optical Line Terminal | +| OMA | Optical Modulation Amplitude | +| ONU | Optical Network Unit | +| OPL | Optical Path Loss | +| OPP | Optical Path Penalty | +| ORL | Optical Return Loss | +| PHY | Physical interface | +| PIN | Positive Intrinsic Negative (photodiode type) | +| PMD | Physical Medium Dependent | +| PON | Passive Optical Network | +| PSBu | Physical Synchronization Block, upstream | +| QoS | Quality of Service | +| R/S | Receive/Send reference point at the interface of the ONU to the ODN | +| Rx | Receiver | + +| | | +|-----------|--------------------------------------------------------------------| +| SLM | Single Longitudinal Mode (laser type) | +| S/R | Send/Receive reference point at the OLT side | +| S/Rm | Send/Receive reference point at the OLT side for MPM case | +| SSPR | Short Stressed Pattern Random | +| T-CONT | Transmission Container | +| TC | Transmission Convergence | +| TDEC | Transmitter and Dispersion Eye Closure | +| TEC | Transmitter Eye Closure | +| TDM | Time Division Multiplexing | +| Tx | Transmitter | +| UI | Unit Interval | +| WBF | Wavelength Blocking Filter | +| WDM | Wavelength Division Multiplexing | +| XG-PON | Asymmetric 10-Gigabit Passive Optical Network (ITU-T G.987 series) | +| XGS-PON | Symmetric 10-Gigabit Passive Optical Network [ITU-T G.9807.1] | +| XG(S)-PON | XG-PON or XGS-PON | +| XGEM | 10-Gigabit-capable PON Encapsulation Method | +| X/S | Crosstalk-to-Signal Ratio | + +# 5 Conventions + +See clause 5 of [ITU-T G.9804.1]. + +# 6 Architecture of the optical access network + +When a PON system is migrated from a legacy PON to a 50G-PON, there can be several approaches, among which are the OLT multi-PON module (MPM) method [ITU-T G.984.5] Appendix IV, and the external wavelength division multiplexing (WDM) method [ITU-T G.984.5] Appendix I. + +Figure 6-1 shows the general architectural reference diagram of 50G-PON coexisting with legacy PON using the OLT MPM method (see below for a definition of the reference points in the figure). + +![Figure 6-1: General architectural reference diagram of 50G-PON coexisting with legacy PON using the OLT MPM method. The diagram shows an OLT port containing an OLT multi-PON module. This module includes a Legacy PON OLT transceiver and a 50G PON OLT transceiver connected to a WDM (Wavelength Division Multiplexer). The WDM output is connected to an Optical Distribution Network (ODN), which consists of a fiber and a Splitter. The Splitter has two outputs: one connected to a Legacy PON ONU and another connected to a 50G PON ONU. Reference points S/Rm and R/S are indicated by vertical dashed lines. S/Rm is at the OLT side of the ODN, and R/S is at the ONU side of the ODN.](ddc7460821484f1ae2835c67955c554c_img.jpg) + +Figure 6-1: General architectural reference diagram of 50G-PON coexisting with legacy PON using the OLT MPM method. The diagram shows an OLT port containing an OLT multi-PON module. This module includes a Legacy PON OLT transceiver and a 50G PON OLT transceiver connected to a WDM (Wavelength Division Multiplexer). The WDM output is connected to an Optical Distribution Network (ODN), which consists of a fiber and a Splitter. The Splitter has two outputs: one connected to a Legacy PON ONU and another connected to a 50G PON ONU. Reference points S/Rm and R/S are indicated by vertical dashed lines. S/Rm is at the OLT side of the ODN, and R/S is at the ONU side of the ODN. + +**Figure 6-1 – General architectural reference diagram of 50G-PON coexisting with legacy PON using the OLT MPM method** + +Figure 6-2 shows the general architectural reference diagram of 50G-PON coexisting with legacy PON using the external coexistence element type x (CEx) method (see below for a definition of the reference points in the figure). When there is no coexistence requirement, the 50G-PON OLT may use a direct ODN connection. + +![Figure 6-2: General architectural reference diagram of 50G-PON coexisting with legacy PON using the external CEx method. The diagram shows two OLTs (Legacy PON OLT and 50G PON OLT) connected to a CEx (Coexistence Element). The CEx is connected to a Splitter via an optical fiber. The Splitter is connected to multiple ONUs (Legacy PON ONU and 50G PON ONU) via optical fibers. The ODN (Optical Distribution Network) is shown between the CEx and the Splitter. Reference points S/R and R/S are indicated at the ends of the ODN.](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg) + +The diagram illustrates the optical architecture for 50G-PON coexisting with legacy PON using the external CEx method. On the left, two OLTs are shown: 'Legacy PON OLT' and '50G PON OLT'. Both are connected to a trapezoidal component labeled 'CEx'. From the CEx, an optical fiber (represented by a line with two circles) leads to a triangular component labeled 'Splitter'. The Splitter has multiple output fibers leading to ONUs on the right. The first output is labeled 'Legacy PON ONU', followed by a vertical ellipsis, and then '50G PON ONU'. Above the diagram, a double-headed arrow labeled 'ODN' spans between two vertical dashed lines. The left dashed line is labeled 'S/R' and the right one is labeled 'R/S'. In the bottom right corner, the text 'G.9804.3(21)' is present. + +Figure 6-2: General architectural reference diagram of 50G-PON coexisting with legacy PON using the external CEx method. The diagram shows two OLTs (Legacy PON OLT and 50G PON OLT) connected to a CEx (Coexistence Element). The CEx is connected to a Splitter via an optical fiber. The Splitter is connected to multiple ONUs (Legacy PON ONU and 50G PON ONU) via optical fibers. The ODN (Optical Distribution Network) is shown between the CEx and the Splitter. Reference points S/R and R/S are indicated at the ends of the ODN. + +**Figure 6-2 – General architectural reference diagram of 50G-PON coexisting with legacy PON using the external CEx method** + +The following reference points are defined in Figure 6-1 and Figure 6-2: + +- S: Point on the optical fibre just after the OLT [Downstream]/ONU [Upstream] optical connection point (i.e., optical connector or optical splice). +- R: Point on the optical fibre just before the ONU [Downstream]/OLT [Upstream] optical connection point (i.e., optical connector or optical splice). +- S/Rm: Combination of points S and R existing simultaneously at the common port of WDM in a single fibre in the OLT MPM method, when operating in bidirectional mode. +- R/S: Combination of points R and S existing simultaneously in a single fibre, when operating in bidirectional mode. +- S/R: Combination of points S and R existing simultaneously in a single fibre in non-MPM and direct ODN connection use cases, when operating in bidirectional mode. + +The two directions for optical transmission in the ODN are identified as follows: + +- Downstream direction for signals travelling from the OLT to the ONU(s), and +- Upstream direction for signals travelling from the ONU(s) to the OLT. + +Transmission in downstream and upstream directions takes place on the same fibre and components (duplex/diplex configuration). + +## 6.1 Classes for optical path loss + +The classes for optical path loss using the OLT MPM method and external CEx method (or direct ODN connection method) are shown in Table 6-1 and Table 6-2, respectively. + +**Table 6-1 – ODN optical path loss classes (ODN classes) for the OLT MPM method** + +| OPL class | Class N1 | Class C+ | +|---------------------------|----------|----------| +| Minimum optical path loss | 14 dB | 17 dB | +| Maximum optical path loss | 29 dB | 32 dB | + +**Table 6-2 – ODN optical path loss classes (ODN classes) for non-MPM use cases using external CEx or direct ODN connection methods** + +| OPL class | Class N1 | Class N2 | Class E1 | Class E2 | +|---------------------------|----------|----------|----------|----------| +| Minimum optical path loss | 14 dB | 16 dB | 18 dB | 20 dB | +| Maximum optical path loss | 29 dB | 31 dB | 33 dB | 35 dB | + +All the physical medium dependent (PMD) parameters for class N1 in Table 6-2 are same as those for Class N1 in clause 9.2.6. + +PMD related parameters for Class N2, E1 and E2 in Table 6-2 are for further study (FFS). + +## 6.2 Categories for fibre differential distance + +The categories for fibre differential distance (DD) are shown in Table 6-3. + +**Table 6-3 – Categories for fibre DD defined in this Recommendation** + +| | DD20 | DD40 | +|-----------------------------------------|-------|-------| +| Maximum differential distance | 20 km | 40 km | +| NOTE – Specifications for DD40 are FFS. | | | + +7 This clause is intentionally left blank + +8 This clause is intentionally left blank + +# 9 Optical network requirements + +## 9.1 Layered structure of optical network + +The protocol reference model is divided into the physical medium, as defined in this Recommendation, transmission convergence (TC) [ITU-T G.9804.2] and path layers (see [ITU-T G.902]). An example applied to 50G-PON is shown in Table 9-1. + +**Table 9-1 – Layered structure of 50G-PON protocol reference model** + +| Path layer | | | | +|--------------------------------------------------------------------------|----------------------------------------------------------|----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmission medium layer (see Note) | TC layer | Service adaptation | XGEM encapsulation | +| | | Framing and PHY adaptation | DBA
XGEM port bandwidth allocation
QoS handling and T-CONT management
Privacy and security
Frame alignment
Ranging
Burst synchronization
Bit/byte synchronization | +| | PMD layer | | | +| | Electrical/Optical adaptation
WDM
Fibre connection | | | +| NOTE – The transmission medium layer provides the related OAM functions. | | | | + +## 9.2 PMD layer requirements for the 50G-PON + +All parameters are specified as follows, and are in accordance with Tables 9-5 to 9-8. + +All parameter values specified are worst-case values to be met over the range of standard operating conditions (i.e., temperature and humidity), and include ageing effects. The parameters are specified relative to an optical section design objective of a bit error ratio (BER) not worse than the values specified in Tables 9-5 to 9-8, for the extreme case of optical path attenuation and dispersion conditions. + +### 9.2.1 Line rate + +The transmission line rate is a multiple of 8 kHz. This Recommendation defines a downstream line rate of 49.7664 Gbit/s and three upstream line rates shown in Table 9-2. + +**Table 9-2 – 50G-PON Line rates** + +| Direction | Units | Line rate | +|------------|--------|-----------| +| Downstream | Gbit/s | 49.7664 | +| Upstream | Gbit/s | 49.7664 | +| | Gbit/s | 24.8832 | +| | Gbit/s | 12.4416 | + +#### 9.2.1.1 Downstream frequency accuracy + +When the OLT and its timing source are in their normal operating state, the OLT is typically traceable to a Stratum-1 reference (accuracy of $1 \times 10^{-11}$ ). When the OLT is in its free-running mode, the accuracy of the downstream signal is at least that of a Stratum-4 clock ( $3.2 \times 10^{-5}$ ). Those OLTs intended for timing-critical applications such as mobile backhaul may require Stratum-3 clock ( $4.6 \times 10^{-6}$ ) quality in free-running mode. + +NOTE – The OLT may derive its timing either from a dedicated timing signal source or from a synchronous data interface (line timing). A packet-based timing source may also be used. + +#### 9.2.1.2 Upstream frequency accuracy + +When in one of its operating states and granted an allocation, the ONU shall transmit its signal with frequency accuracy equal to that of the received downstream signal, with jitter limited to the values defined in clause 9.2.9.7. + +### 9.2.2 Forward error correction (FEC) code selection for 50G-PON + +The forward error correction (FEC) codes used for 50G-PON are indicated in Table 9-3. + +**Table 9-3 – FEC codes used for 50G-PON** + +| Direction | Line rate | Type | Notation | BER reference level | FEC code [ITU-T G.9804.2] | +|------------|----------------|------|---------------------|---------------------|---------------------------| +| Downstream | 49.7664 Gbit/s | LDPC | LDPC (17280, 14592) | 1E-2 | Annex B.1.2 | +| Upstream | 49.7664 Gbit/s | FFS | FFS | FFS | FFS | +| | 24.8832 Gbit/s | LDPC | LDPC (17280, 14592) | 1E-2 | Annex B.1.2 | +| | 12.4416 Gbit/s | LDPC | LDPC (17280, 14592) | 1E-2 | Annex B.1.2 | + +Additional optional upstream FEC codes are FFS in [ITU-T G.9804.2]. + +### **9.2.3 Physical media and transmission method** + +#### **9.2.3.1 Transmission medium** + +This Recommendation is based on the fibre described in [ITU-T G.652]. Other fibre types may be compatible with this Recommendation, e.g., [ITU-T G.657] fibre used, for example, for in-building cabling, drop section. + +#### **9.2.3.2 Transmission direction** + +The signal is transmitted both upstream and downstream through the transmission medium. + +#### **9.2.3.3 Transmission methodology** + +Bidirectional transmission is accomplished by the use of WDM technique on a single fibre. + +### **9.2.4 Line code and interleaving** + +The scrambling method and any interleaving method (if applicable) are defined in [ITU-T G.9804.2]. + +The convention used for optical logic levels is: + +- High level of light emission for a binary ONE; +- Low level of light emission for a binary ZERO. + +#### **9.2.4.1 Downstream** + +Downstream line coding for 50G-PON: Scrambled NRZ with optional interleaving. + +The scrambling method is defined in clause 10.4.1 of [ITU-T G.9804.2]. + +The interleaving method is defined in clause 10.5 of [ITU-T G.9804.2]: + +- Interleaving is optionally on – at the discretion of the OLT. +- Interleaving Depth $D = 4$ . + +#### **9.2.4.2 Upstream** + +Upstream line coding for 50G-PON: + +12.4416 Gbit/s: Scrambled NRZ, + +24.8832 Gbit/s: Scrambled NRZ, + +49.7664 Gbit/s: FFS + +The scrambling method is defined in clause 10.4.2 of [ITU-T G.9804.2]. + +NOTE – Interleaving in the upstream direction for 12.4416 Gbit/s and 24.8832 Gbit/s upstream line rates is not used. Use of interleaving for line rate 49.7664 Gbit/s is FFS. + +### **9.2.5 Operating wavelength** + +#### **9.2.5.1 Downstream wavelength allocation** + +The operating wavelength range for 50G-PON for the downstream direction is defined in Table 9-5. + +#### **9.2.5.2 Upstream wavelength allocation** + +The operating wavelength range for 50G-PON for the upstream direction is defined in Tables 9-6 to 9-8. + +### **9.2.6 50G-PON PMD parameters** + +#### **9.2.6.1 50G-PON compatible ODN** + +50G-PON shall operate over an ODN whose parameters are described by Table 9-4a. Table 9-4a shows the physical parameters of the optical distribution segment (ODS). Table 9-4b shows the 3 bits + +ODN class encoding in PON-ID (PIT) for 50G-PON; for more details see clause 10.1.1.3 in [ITU-T G.9804.2]. + +**Table 9-4a – Physical parameters of a simple ODN (ODS)** + +| Item | Unit | Specification | +|-------------------------------------------------------------|-----------------------------------------------------------------------|--------------------------------------------------------------------------------| +| Fibre type (Note) | – | [ITU-T G.652] or compatible | +| Attenuation range (as defined in clause 6.1) | MPM-based coexistence | dB
Class N1: 14–29
Class C+: 17–32 | +| | Non-MPM use cases using external CEx or direct ODN connection methods | dB
Class N1: 14–29
Class N2: 16–31
Class E1: 18–33
Class E2: 20–35 | +| Maximum fibre distance between S/R (or S/Rm) and R/S points | km | DD20: 20
DD40: 40 | +| Minimum fibre distance between S/R (or S/Rm) and R/S points | km | 0 | +| Bidirectional transmission | – | 1-fibre WDM | +| Maintenance wavelength | nm | [ITU-T L.3.13] | +| NOTE – See clause 9.2.3.1 | | | + +**Table 9-4b – ODN optical path loss (OPL) class encoding** + +| Code value | ODN OPL class | +|------------|---------------| +| 000 | N1 | +| 001 | N2 | +| 010 | E1 | +| 011 | E2 | +| 100 | C+ | +| 101-111 | Reserved | + +#### 9.2.6.2 Optical interface parameters of 49.7664 Gbit/s downstream direction + +**Table 9-5 – Optical interface parameters of 49.7664 Gbit/s downstream direction** + +| Item | Unit | Value | +|-----------------------------------------------------------------|--------|----------------------| +| OLT transmitter (optical interface S/Rm) | | | +| Nominal line rate | Gbit/s | 49.7664 | +| Operating wavelength | nm | 1340–1344 | +| Line code | – | NRZ | +| Mask of the transmitter eye diagram | – | See clause 9.2.7.6.1 | +| Maximum reflectance at S/Rm, measured at transmitter wavelength | dB | NA | +| Minimum ORL of ODN (Note 1) | dB | 32 | + +**Table 9-5 – Optical interface parameters of 49.7664 Gbit/s downstream direction** + +| Item | Unit | Value | | +|----------------------------------------------------------------|-------|-----------------------------|------------------| +| ODN Class | | N1                      C1+ | | +| Mean launch power minimum (Note 2) | dBm | +5.5
(Note 3) | +8.5
(Note 4) | +| Mean launch power maximum | dBm | +11 | +14 | +| Launch power in OMA minus TDEC (min) (Note 5) | dBm | +4.75 | +7.75 | +| Maximum transmitter and dispersion eye closure (TDEC) (Note 5) | dB | 5 | | +| Launch optical power without input to the transmitter | dBm | NA | | +| Minimum extinction ratio (Note 6) | dB | 7 | | +| Transmitter tolerance to reflected optical power (Note 7) | dB | More than −15 | | +| Dispersion range (DD20) | ps/nm | 0~77.1 | | +| Minimum side mode suppression ratio | dB | 30 | | +| Maximum differential optical path loss | dB | 15 | | +| Jitter generation | – | See clause 9.2.9.7.3 | | +| ONU receiver (optical interface R/S) | | | | +| Maximum optical path penalty (DD20) (Note 8) | dB | 3.5 | | +| Maximum reflectance at R/S, measured at receiver wavelength | dB | −20 | | +| Bit error ratio reference level (Notes 9, 10) | – | 1.0E-2 | | +| ODN class | | N1                      C+ | | +| Sensitivity at BER reference level (Note 11) | dBm | −24.0 | −24.0 | +| OMA Sensitivity at BER reference level | dBm | −22.75 | −22.75 | +| Overload at BER reference level (Note 12) | dBm | −3 | −3 | +| Consecutive identical digit immunity | bit | 72 | | +| Jitter tolerance | – | See clause 9.2.9.7.2 | | +| Receiver tolerance to reflected optical power | dB | Less than 10 | | + +NOTE 1 – There are optional cases where the "minimum ORL of ODN at S/Rm and R/S" can be as low as 20 dB. (See Appendix I of [ITU-T G.983.1]). + +NOTE 2 – A lower "mean launch power minimum" is allowed but will be compensated by a higher extinction ratio, within the limits of the "Launch power in OMA minus TDEC (min)" value. If the actual TDEC is worse than 2.0 dB, it will be compensated by increasing the transmitter mean launch power minimum specification by $X$ dB for each $X$ dB of extra TDEC allowance, where $X \leq 3.0$ dB, while meeting all other Tx specifications. + +NOTE 3 – The mean launch power minimum value is consistent with a minimum "OMA minus TDEC" of +4.75 dBm when ER = 7 dB and TDEC = 2.0 dB. Even if the TDEC is lower than 2.0 dB, the mean launch power minimum should still exceed this value at 7 dB ER. + +**Table 9-5 – Optical interface parameters of 49.7664 Gbit/s downstream direction** + +| Item | Unit | Value | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|-------| +| NOTE 4 – The mean launch power minimum value is consistent with a minimum "OMA minus TDEC" of +7.75 dBm when ER = 7 dB and TDEC = 2.0 dB. Even if the TDEC is lower than 2.0 dB, the mean launch power minimum should still exceed this value at 7 dB ER.
NOTE 5 – TDEC is measured, following the method in clause 9.2.7.8, using an appropriate fibre length to ensure the worst-case eye closure penalty over the full dispersion range.
NOTE 6 – This "minimum extinction ratio" is the minimum value required to meet the "mean launch power minimum" value in this table. A lower extinction ratio is allowed if compensated by a larger transmitter launch power within the limits of the "mean launch power maximum" value. In no case should the ER be lower than 5 dB. A lower "mean launch power minimum" is allowed if compensated by a higher extinction ratio. For quantitative treatment examples of these tradeoffs, see Appendix I.
NOTE 7 – Parameter known in [ITU-T G.984.2] as "tolerance to the transmitter incident light power".
NOTE 8 – Optical path penalty is informative.
NOTE 9 – See clause 9.4.1 of [b-ITU-T G.Sup39] for additional details on BER in FEC enabled applications.
NOTE 10 – This BER reference level assumes hard-decision FEC decoding with interleaving defined in [ITU-T G.9804.2]. Without interleaving, this BER reference level may not achieve the target FEC output BER of 1e-12. When soft-decision FEC decoding is used, this value is higher.
NOTE 11 – This Rx sensitivity is based on a transmitter with a transmitter eye closure (TEC) = 1.5 dB at 7 dB extinction ratio in back to back; it is equivalent to -22.75 dBm sensitivity in OMA. In addition, the Rx sensitivity in OMA with fibre, R(TDEC), should also comply with $R(TDEC) \leq \text{maximum}(-22.25, TDEC - 24.25)$ dBm using an appropriate fibre length to ensure the worst-case eye closure within the dispersion range. (For $TDEC \leq 5.0$ dB), see Figure 9-1.
NOTE 12 – Overload is based on a received signal with worst-case TDEC. | | | + +For the C+ OPL class, Figure 9-1 illustrates the relationship between TDEC and both the OLT transmitter power and the ONU receiver sensitivity specifications. Moreover, Appendix IV provides additional information on the relationship among between optical interface parameters specified in Table 9-5 for 49.7664 Gbit/s downstream. + +![Figure 9-1: Illustration of the relationship between transmitter power, receiver sensitivity and TDEC for 49.7664 Gbit/s downstream (C+ OPL class).](5ed9189841659dfb01f809b8e3b21f74_img.jpg) + +The graph shows the relationship between transmitter power, receiver sensitivity, and TDEC for 49.7664 Gbit/s downstream (C+ OPL class). The x-axis represents TDEC (dB) from 0.0 to 5.0. The left y-axis represents Tx power in OMA (dBm) from 9.75 to 15.25. The right y-axis represents Rx sensitivity in OMA (dBm) from -22.75 to -19.25. A horizontal line at 15.25 dBm is labeled 'Tx OMA maximum'. A horizontal line at 9.75 dBm is labeled 'Tx OMA minimum'. A vertical double-headed arrow between these two lines is labeled 'ODN loss 32 dB (C+)'. A diagonal line labeled 'Rx sensitivity with fibre, R (TDEC)' starts at -22.75 dBm at TDEC min (approx. 1.5 dB) and increases to -19.25 dBm at TDEC max (5.0 dB). A point on the left y-axis is labeled 'Rx sensitivity without fibre at TEC = 1.5 dB'. + +Figure 9-1: Illustration of the relationship between transmitter power, receiver sensitivity and TDEC for 49.7664 Gbit/s downstream (C+ OPL class). + +Figure 9-1 – Illustration of the relationship between transmitter power, receiver sensitivity and TDEC for 49.7664 Gbit/s downstream (C+ OPL class) + +#### 9.2.6.3 Optical interface parameters of upstream direction + +Table 9-6 – Optical interface parameters of 12.4416 Gbit/s upstream direction + +| Item | Unit | Value | | +|-----------------------------------------------------------------------------|--------|----------------------|-----------| +| ONU transmitter (optical interface R/S) | | | | +| Nominal line rate | Gbit/s | 12.4416 | | +| Operating wavelength | nm | Option 1 | Option 2 | +| | | 1260~1280 | 1290~1310 | +| Line code | – | NRZ | | +| Mask of the transmitter eye diagram | – | See clause 9.2.7.6.2 | | +| Maximum reflectance of equipment at R/S, measured at transmitter wavelength | dB | –10 | | +| Minimum ORL of ODN (Note 1) | dB | 32 | | +| ODN Class | | N1 | C+ | +| Mean launch power minimum (Note 2) | dBm | +4.0 | +4.0 | +| Mean launch power maximum | dBm | +9.0 | +9.0 | +| Launch optical power without input to the transmitter (Note 3) | dBm | Less than –45 | | + +**Table 9-6 – Optical interface parameters of 12.4416 Gbit/s upstream direction** + +| Item | Unit | Value | | | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|------------------------------------------------|-------|--|--| +| Maximum Tx enable time (Note 3) | bits (ns) | 1600 (~128.6) | | | | +| Maximum Tx disable time (Note 3) | bits (ns) | 1600 (~128.6) | | | | +| Minimum extinction ratio (Note 2) | dB | 6 | | | | +| Transmitter tolerance to reflected optical power (Note 4) | dB | More than –15 | | | | +| Dispersion range (DD20) | ps/nm | 0 to –140 (option 1)
–66 to 18.4 (option 2) | | | | +| Minimum side mode suppression ratio | dB | 30 | | | | +| Jitter transfer | – | See clause 9.2.9.7.1 | | | | +| Jitter generation | – | See clause 9.2.9.7.3 | | | | +| OLT receiver (optical interface S/Rm) | | | | | | +| ODN Class | | N1 | C+ | | | +| Maximum optical path penalty (DD20) | dB | 1.0 | 1.0 | | | +| Maximum reflectance at S/Rm, measured at receiver wavelength | dB | -12 | | | | +| Bit error ratio reference level (Note 5)
(Note 6) | – | 1.0E-2 | | | | +| ODN class | | N1 | C+ | | | +| Sensitivity at BER reference level (Note 7) | dBm | –26.0 | –29.0 | | | +| Overload at BER reference level | dBm | –5.0 | –8.0 | | | +| Consecutive identical digit immunity | bit | 72 | | | | +| Jitter tolerance | – | See clause 9.2.9.7.2 | | | | +| NOTE 1 – There are optional cases where the "minimum ORL of ODN at S/Rm and R/S" can be as low as 20 dB. (See Appendix I of [ITU-T G.983.1]). | | | | | | +| NOTE 2 – The minimum average launch power and the minimum ER are consistent with a minimum OMA of 4.78 dBm. (For further details, see Figure I.1.1 of Appendix I in [ITU-T G.9807.1]). | | | | | | +| NOTE 3 – As defined in clause 9.2.7.3.1. The values in nanoseconds are informative. | | | | | | +| NOTE 4 – Parameter known in [ITU-T G.984.2] as "tolerance to the transmitter incident light power". | | | | | | +| NOTE 5 – See clause 9.4.1 of [b-ITU-T G.Sup39] for additional details on BER in FEC enabled applications. | | | | | | +| NOTE 6 – This BER reference level assumes hard-decision FEC decoding. When soft-decision FEC decoding is used, this value is higher. | | | | | | +| NOTE 7 – The sensitivity is based on ER = 6.0 dB received signal. | | | | | | + +**Table 9-7 – Optical interface parameters of 24.8832 Gbit/s upstream direction** + +| Item | Unit | Value | | | +|----------------------------------------------------------------|----------------|-------------------------------------------------------------------------------------|---------------------------|--| +| ONU transmitter (optical interface R/S) | | | | | +| Nominal line rate | Gbit/s | 24.8832 | | | +| Operating wavelength | nm | Option 1 | Option 2 | | +| | | 1260~1280 | 1290~1310
(wideband) | | +| | | | 1298~1302
(narrowband) | | +| Line code | – | NRZ | | | +| Mask of the transmitter eye diagram | – | See clause 9.2.7.6.2 | | | +| Maximum reflectance at R/S, measured at transmitter wavelength | dB | –10 | | | +| Minimum ORL of ODN (Note 1) | dB | 32 | | | +| ODN Class | | N1 | C+ | | +| Mean launch power minimum (Note 2) | dBm | +5 | +5 | | +| Mean launch power maximum | dBm | +9 | +9 | | +| Launch power in OMA minus OPP (min) | dBm | 4.7
4.5 | 4.7
4.5 | | +| – When ER < 6 dB
– When ER ≥ 6 dB | | | | | +| Launch optical power without input to the transmitter (Note 3) | dBm | Less than –45 | | | +| Maximum Tx enable time (Note 3) | Bits
(nsec) | 3200
(~128.6) | | | +| Maximum Tx disable time (Note 3) | Bits
(nsec) | 3200
(~128.6) | | | +| Minimum extinction ratio (Note 4) | dB | 5 | | | +| Transmitter tolerance to reflected optical power (Note 5) | dB | More than –15 | | | +| Dispersion range (DD20) | ps/nm | 0 to –140 (option 1)
–66 to 18.4 (option 2 wide)
–50 to 3.7 (option 2 narrow) | | | +| Minimum side mode suppression ratio | dB | 30 | | | +| Jitter transfer | – | See clause 9.2.9.7.1 | | | +| Jitter generation | – | See clause 9.2.9.7.3 | | | +| OLT receiver (optical interface S/Rm) | | | | | +| Maximum optical path penalty (DD20) | dB | 1.5 | | | +| Maximum reflectance at S/Rm, measured at receiver wavelength | dB | –12 | | | +| Bit error ratio reference level (Notes 6, 7) | – | 1.0E-2 | | | +| ODN class | | N1 | C+ | | +| Sensitivity at BER reference level (Note 8) | dBm | –24.5 | –27.5 | | +| Overload at BER reference level | dBm | –5 | –8 | | + +**Table 9-7 – Optical interface parameters of 24.8832 Gbit/s upstream direction** + +| Item | Unit | Value | +|--------------------------------------|------|----------------------| +| Consecutive identical digit immunity | bit | 72 | +| Jitter tolerance | – | See clause 9.2.9.7.2 | + +NOTE 1 – There are optional cases where the "minimum ORL of ODN at S/Rm and R/S" can be as low as 20 dB. (See Appendix I of [ITU-T G.983.1].) + +NOTE 2 – The mean launch power minimum value is consistent with a minimum "OMA minus OPP" of 4.7 dBm when ER = 5 dB and OPP = 0.5 dB. A lower "mean launch power minimum" is allowed but will be compensated by a higher extinction ratio, within the limits of the "launch power in OMA minus OPP (min)" value. If the actual OPP is worse than 0.5 dB, it will be compensated by increasing the transmitter mean launch power minimum specification by $X$ dB for each $X$ dB of extra OPP allowance, where $X < 1.0$ dB while meeting all other Tx specifications. For a quantitative treatment of these tradeoffs, see Appendix I. + +NOTE 3 – As defined in clause 9.2.7.3.1. The values in nanoseconds are informative. + +NOTE 4 – A lower extinction ratio is allowed but will be compensated by a larger transmitter launch power within the limits of the "mean launch power maximum" value. A lower "mean launch power minimum" is allowed but will be compensated by a higher extinction ratio. For quantitative treatment of these trade-offs, see Appendix I. + +NOTE 5 – Parameter known in [ITU-T G.984.2] as "tolerance to the transmitter incident light power". + +NOTE 6 – See clause 9.4.1 of [b-ITU-T G.Sup39] for additional details on BER in FEC enabled applications. + +NOTE 7 – This BER reference level assumes hard-decision FEC decoding. When soft-decision FEC decoding is used, this value is higher + +NOTE 8 – The sensitivity is based on ER = 5.0 dB received signal. + +**Table 9-8 – Optical interface parameters of 49.7664 Gbit/s upstream direction***49.7664 Gbit/s upstream specification is for further study.* + +All the PMD parameters for N1 class at S/Rm in Tables 9-5 to 9-7 are also applicable to N1 class at S/R defined in Table 6-2. + +### 9.2.7 Transmitter at S/R (or S/Rm) and R/S + +All parameters are specified as follows, and are in accordance with Tables 9-5 to 9-8. + +#### 9.2.7.1 Source type + +Considering the attenuation/dispersion characteristics of the target fibre channel, feasible transmitter devices include only single longitudinal mode (SLM) lasers. The indication of a nominal source type in this Recommendation is not a requirement, though it is also expected that only SLM lasers will meet all the distance and line rate requirements of the 50G-PON systems both for the downstream and upstream links. + +The use of multilongitudinal mode (MLM) lasers is not contemplated in this Recommendation due to their practical distance/line-rate limitations. + +#### 9.2.7.2 Spectral characteristics + +For SLM lasers, the laser is specified as its fibre dispersion range, the range over which the laser characteristics and fibre dispersion result in a defined penalty at a specified fibre distance, under standard operating conditions. Additionally, for control of mode partition noise in SLM systems, a minimum value for the laser side mode suppression ratio is specified. The actual spectral + +characteristics are limited by the maximum TDEC or amount of optical path penalty (OPP) produced with the worst-case optical dispersion in the data channel. + +#### 9.2.7.3 Mean launch power + +The mean launch power at the optical interfaces S/R (or S/Rm) and R/S is the average power of a pseudo-random data sequence coupled into the fibre by the transmitter. It is given as a range to allow for some cost optimization and to cover all allowances for operation under standard operating conditions, transmitter connector degradation, measurement tolerances and ageing effects. + +In the operating state, the lower figure is the minimum power to be provided and the higher one is the power that should not be exceeded. + +NOTE – Measurement of the launch power at the R/S optical interface must take into account the bursty nature of the upstream traffic transmitted by the ONUs. + +##### 9.2.7.3.1 Launch optical power without input to the transmitter + +In the upstream direction, the ONU transmitter should ideally launch no power into the fibre in all the bursts that are not assigned to that ONU. However, an optical power level less than or equal to the launch power without input to the transmitter is allowed during bursts that are not assigned to that ONU. During the Tx enable bit period immediately preceding the assigned burst, which may be used for laser pre-bias, and during the Tx disable bit period immediately following the assigned burst, the maximum launch power level allowed is the zero level corresponding to the extinction ratio specified in Tables 9-6 to 9-8. + +The specification of the maximum number of Tx enable and Tx disable bit periods is provided in Tables 9-6 to 9-8. + +The relationship between ONU power levels and burst times is shown in Figure 9-2. + +![Figure 9-2: Relationship between ONU power levels and burst times. The graph shows transmit power over bit durations. The y-axis has '1 Level', '0 Level', and 'Transmit power'. The x-axis is 'Bit durations'. The burst is divided into 'Tx enable', 'Preamble', 'Delimiter', 'Rest of burst', and 'Tx disable'. The 'Rest of burst' shows a power ramp. The 'Launched optical power without input to the transmitter' is indicated by a shaded area below the 0 level during the Tx enable and Tx disable periods.](64f0cbd62402f4f1a601aad887f85b95_img.jpg) + +The figure is a line graph showing the relationship between ONU power levels and burst times. The vertical axis represents 'Transmit power' with two main levels: '1 Level' and '0 Level'. The horizontal axis represents 'Bit durations'. The burst is divided into five segments: 'Tx enable', 'Preamble', 'Delimiter', 'Rest of burst', and 'Tx disable'. During the 'Tx enable' and 'Tx disable' segments, the power is at the '0 Level'. During the 'Preamble' and 'Delimiter' segments, the power is at the '1 Level'. During the 'Rest of burst' segment, the power ramps from the '0 Level' to the '1 Level'. A shaded area below the '0 Level' during the 'Tx enable' and 'Tx disable' segments represents the 'Launched optical power without input to the transmitter'. + +Figure 9-2: Relationship between ONU power levels and burst times. The graph shows transmit power over bit durations. The y-axis has '1 Level', '0 Level', and 'Transmit power'. The x-axis is 'Bit durations'. The burst is divided into 'Tx enable', 'Preamble', 'Delimiter', 'Rest of burst', and 'Tx disable'. The 'Rest of burst' shows a power ramp. The 'Launched optical power without input to the transmitter' is indicated by a shaded area below the 0 level during the Tx enable and Tx disable periods. + +Figure 9-2 – Relationship between ONU power levels and burst times + +#### 9.2.7.4 Minimum extinction ratio + +The ER is defined for ONU transmitters up to 25 Gbit/s as: + +$$ER = 10 \log_{10} (A/B) \quad (9-1)$$ + +where $A$ is the average optical power level at the centre of the binary 1 and $B$ is the average optical power level at the centre of the binary 0. + +The extinction ratio for the upstream direction burst mode signal is applied from the first bit of the preamble to the last bit of the burst signal inclusively. + +NOTE – In the context of this PMD Recommendation, the generic term "preamble" refers to the portion of the upstream physical synchronization block (PSBu), without the delimiter delineating the burst payload. The PSBu is described in clause 10.2.1, Figure 10-6 in [ITU-T G.9804.2]. + +For OLT transmitters that pass the eye mask in clause 9.2.7.6.1 using an equalizer, the extinction ratio is defined as follows: + +$$ER = 10 \log_{10} (P1/P0) \quad (9-2)$$ + +where: + +$P1$ is the average optical power over the central region of the 72-bit sequence of one bits (see Figure 9-8) in a Short Stressed Pattern Random (SSPR) [b-OIF] + +$P0$ is the average optical power over the central region of the 72-bit sequence of zero bits (see Figure 9-8) in an SSPR [b-OIF]. + +#### 9.2.7.5 Maximum reflectance of equipment measured at transmitter wavelength + +Reflections from equipment (ONU/OLT) back to the cable plant are specified by the maximum permissible reflectance of equipment measured at S/R, S/Rm or R/S, in accordance with Tables 9-4 to 9-8. + +#### 9.2.7.6 Mask of transmitter eye diagram + +In this Recommendation, general transmitter pulse shape characteristics including rise time, fall time, pulse overshoot, pulse undershoot and ringing, all of which should be controlled to prevent excessive degradation of the receiver sensitivity, are specified in the form of a mask of the transmitter eye diagram at S/R, S/Rm or R/S. For the purpose of assessing the transmit signal, it is important to consider not only the eye opening but also the overshoot and undershoot limitations. + +##### 9.2.7.6.1 OLT transmitter + +The parameters specifying the mask of the eye diagram (see Figure 9-3) for the OLT transmitter are shown in Table 9-9. The test set-up for the measurement of the mask of the eye diagram is shown in Figure 9-4. The waveform monitoring instrument includes a virtual feed forward equalizer (FFE) using 13 taps (symbol spaced) with coefficients optimized to minimize the eye closure of the measured waveform. The clock recovery unit (CRU) has a corner frequency of 4 MHz and a slope of 20 dB/decade. The CRU can be implemented in hardware or software depending on oscilloscope technology. + +![Figure 9-3: Mask of the eye diagram for OLT transmitter. The diagram shows a normalized eye diagram with a shaded 'mask' area. The horizontal axis represents normalized time from 0 to 1, with markers at 0, x1, x2, x3, 1-x3, 1-x2, 1-x1, and 1. The vertical axis represents normalized amplitude from -y3 to 1+y3, with markers at -y3, 0, y1, y2, 0.5, 1-y2, 1-y1, 1, and 1+y3. The shaded region is bounded by x2 and 1-x2 horizontally, and y1 and 1-y1 vertically. The mean level of the center of logical '1' is indicated at 1, and the mean level of the center of logical '0' is indicated at 0. The text 'G.9804.3(21)' is in the bottom right corner.](bfb6d182d624680db577069bbc0b2a93_img.jpg) + +Figure 9-3: Mask of the eye diagram for OLT transmitter. The diagram shows a normalized eye diagram with a shaded 'mask' area. The horizontal axis represents normalized time from 0 to 1, with markers at 0, x1, x2, x3, 1-x3, 1-x2, 1-x1, and 1. The vertical axis represents normalized amplitude from -y3 to 1+y3, with markers at -y3, 0, y1, y2, 0.5, 1-y2, 1-y1, 1, and 1+y3. The shaded region is bounded by x2 and 1-x2 horizontally, and y1 and 1-y1 vertically. The mean level of the center of logical '1' is indicated at 1, and the mean level of the center of logical '0' is indicated at 0. The text 'G.9804.3(21)' is in the bottom right corner. + +**Figure 9-3 – Mask of the eye diagram for OLT transmitter** + +**Table 9-9 – Mask of the eye diagram for OLT transmitter – Numeric values** + +| | 49.7664 Gbit/s | +|-------------------|-----------------------| +| x1 | 0.25 | +| x2 | 0.425 | +| x3 | 0.45 | +| y1 | 0.25 | +| y2 | 0.28 | +| y3 | 0.4 | +| Maximum hit ratio | $5 \times 10^{-5}$ | + +NOTE – The values are taken from clause 7.2.2.14 of [ITU-T G.959.1], "NRZ 10G Ratio small". The "hit ratio" is the acceptable ratio of samples inside to outside the shaded area. + +![Figure 9-4: Test set-up for mask of the eye diagram for OLT transmitter. The block diagram shows a sequence of four components: 'Optical transmitter' -> 'Attenuator a)' -> 'O/E converter fourth order Bessel-Thomson filter b)' -> 'Waveform monitor'. The text '[Test set-up]' is above the first component. The text 'G.9804.3(21)' is in the bottom right corner.](4cde160bcc69b7b6c81b648dd0e4252e_img.jpg) + +``` + +graph LR + A[Optical transmitter] --> B[Attenuator a)] + B --> C[O/E converter fourth order Bessel-Thomson filter b)] + C --> D[Waveform monitor] + +``` + +Figure 9-4: Test set-up for mask of the eye diagram for OLT transmitter. The block diagram shows a sequence of four components: 'Optical transmitter' -> 'Attenuator a)' -> 'O/E converter fourth order Bessel-Thomson filter b)' -> 'Waveform monitor'. The text '[Test set-up]' is above the first component. The text 'G.9804.3(21)' is in the bottom right corner. + +a) Attenuator is used if necessary + +b) Cut-off frequency (3 dB attenuation frequency) of filter is 0.75 times output nominal bit rate + +**Figure 9-4 – Test set-up for mask of the eye diagram for OLT transmitter** + +For 49.7664 Gbit/s downstream, the fourth order Bessel-Thomson filter cut-off frequency is equal to 37.3 GHz. + +##### 9.2.7.6.2 ONU transmitter + +The parameters specifying the mask of the eye diagram (see Figure 9-5) for the ONU transmitter are shown in Table 9-10. The test set-up for the measurement of the mask of the eye diagram is shown in Figure 9-6. The CRU has a corner frequency of 4 MHz and a slope of 20 dB/decade. The CRU can be implemented in hardware or software depending on oscilloscope technology. + +![Figure 9-5: Mask of the eye diagram for ONU transmitter. The diagram shows a normalized eye diagram with a central black eye shape. The vertical axis represents signal level from 0 to 1, with markers at 0, y1, y2, 0.5, 1-y2, 1-y1, 1, and 1+y3. The horizontal axis represents time from 0 to 1, with markers at 0, x1, x2, x3, 1-x3, 1-x2, 1-x1, and 1. Two shaded regions represent the mask: a dark grey inner region and a light grey outer region. Horizontal dashed lines indicate the mean level of the center of logical '1' (at level 1) and logical '0' (at level 0). The diagram is labeled G.9804.3(21).](2a23751710f7827065d2b99b6df588df_img.jpg) + +Figure 9-5: Mask of the eye diagram for ONU transmitter. The diagram shows a normalized eye diagram with a central black eye shape. The vertical axis represents signal level from 0 to 1, with markers at 0, y1, y2, 0.5, 1-y2, 1-y1, 1, and 1+y3. The horizontal axis represents time from 0 to 1, with markers at 0, x1, x2, x3, 1-x3, 1-x2, 1-x1, and 1. Two shaded regions represent the mask: a dark grey inner region and a light grey outer region. Horizontal dashed lines indicate the mean level of the center of logical '1' (at level 1) and logical '0' (at level 0). The diagram is labeled G.9804.3(21). + +**Figure 9-5 – Mask of the eye diagram for ONU transmitter** + +![](b235edb1dbe659e2782c9a0e47775ca4_img.jpg) + +``` + +graph LR + A("[Test set-up] +Optical +transmitter") --> B("Attenuator a)") + B --> C("O/E converter +fourth order Bessel- +Thomson filter b)") + C --> D("Waveform +monitor") + +``` + +G.9804.3(21) + +a) Attenuator is used if necessary + +b) Cut-off frequency (3 dB attenuation frequency) of filter is 0.75 times output nominal bit rate + +**Figure 9-6 – Test set-up for mask of the eye diagram for ONU transmitter** + +**Table 9-10 – Mask of the eye diagram for ONU transmitter – Numeric values** + +| | 12.4416 Gbit/s | 24.8832 Gbit/s | 49.7664 Gbit/s | +|------------------------------------------------------------------------------------------------------|--------------------|--------------------|----------------| +| x1 | 0.25 | 0.31 | FFS | +| x2 | 0.4 | 0.4 | FFS | +| x3 | 0.45 | 0.45 | FFS | +| y1 | 0.25 | 0.34 | FFS | +| y2 | 0.28 | 0.38 | FFS | +| y3 | 0.4 | 0.4 | FFS | +| Maximum hit ratio | $5 \times 10^{-5}$ | $5 \times 10^{-5}$ | FFS | +| NOTE – The "hit ratio" is the acceptable ratio of samples inside to outside the hatched/shaded area. | | | | + +The mask of the eye diagram for the upstream direction burst mode signal is applied from the first bit of the preamble to the last bit of the burst signal inclusively. + +#### 9.2.7.7 Transmitter tolerance to reflected optical power + +The specified transmitter performance must be met in the presence of the optical reflection level at reference point S specified in Tables 9-5 to 9-8. + +#### 9.2.7.8 Transmitter and dispersion eye closure + +Transmitter and dispersion eye closure (TDEC) is a parameter used to characterize the quality of an optical transmitter. It measures vertical eye closure based on histogram data from eye diagrams captured in an oscilloscope with an optical-to-electrical converter. Within the test instrument, filtering is implemented to limit the bandwidth to that defined by a reference receiver. Furthermore, equalization of the captured (and filtered) waveform is performed inside the instrument using a virtual reference equalizer. The final TDEC value is determined by both the closure of the tested eye diagram after equalization and the noise enhancement factor of the equalizer. For background relating to the TDEC method described here, consult clauses 95.8.5 and 121.8.5.3 of [IEEE 802.3]. + +The TDEC method defined in this Recommendation is not exactly the same as that given clause 95.8.5 of [IEEE 802.3]. The key differences are that noise enhancement from the reference equalizer (similar to clause 121.8.5.3 of [IEEE 802.3]) and the noise properties of avalanche photodiode (APD) based receivers, as typically used in PON, are accounted for in the TDEC calculation in clause 9.2.7.8.1. + +The general test set-up used for the measurement of TDEC is shown in Figure 9-7. + +![Figure 9-7: Test set-up for TDEC measurement of an optical transmitter. The diagram shows a block diagram of the test setup. An Optical transmitter is connected to a Fibre. The output of the Fibre is connected to an O/E converter. The output of the O/E converter is connected to a CRU (Clock Recovery Unit). The output of the O/E converter also branches to the CRU, which then connects to the Pattern triggered oscilloscope. The output of the Pattern triggered oscilloscope is connected to a Reference equalizer and analysis. The text 'G.9804.3(21)' is visible in the bottom right corner of the diagram.](474a819357587e34949a3e110ff19b30_img.jpg) + +``` + +graph LR + A[Optical transmitter] --> B((Fibre)) + B --> C[O/E converter] + C --> E[Pattern triggered oscilloscope] + C --> D[CRU] + D --> E + E --> F[Reference equalizer and analysis] + +``` + +Figure 9-7: Test set-up for TDEC measurement of an optical transmitter. The diagram shows a block diagram of the test setup. An Optical transmitter is connected to a Fibre. The output of the Fibre is connected to an O/E converter. The output of the O/E converter is connected to a CRU (Clock Recovery Unit). The output of the O/E converter also branches to the CRU, which then connects to the Pattern triggered oscilloscope. The output of the Pattern triggered oscilloscope is connected to a Reference equalizer and analysis. The text 'G.9804.3(21)' is visible in the bottom right corner of the diagram. + +**Figure 9-7 – Test set-up for TDEC measurement of an optical transmitter** + +The CRU has a corner frequency of 4 MHz and a slope of 20 dB/decade. The CRU can be implemented in hardware or software depending on oscilloscope technology. + +##### 9.2.7.8.1 OLT TDEC test method + +For the 50G-PON OLT transmitter, the test set-up in Figure 9-7 is used with the following configuration: + +- The test pattern applied to the optical transmitter is a SSPR pattern as defined in Annex 2.D.2 of OIF-CEI-04.0 [b-OIF]. +- Optical-to-electrical (O/E) converters are assumed to be PIN photodiode. +- The overall response of the O/E converter and subsequent filtering matches a reference receiver with a fourth order Bessel-Thomson response with a 3 dB bandwidth of 18.75 GHz. +- A reference equalizer is applied to the waveform after filtering with the following characteristics: FFE with 13 symbol spaced taps. The tap weights of the reference equalizer are optimized to give a minimum mean-squared error for the eye closure. +- The fibre link for the test should be set up to emulate the worst-case link parameters, such as reflections, as specified in this Recommendation. + +The test instrument monitoring the waveforms should be configured to capture the complete SSPR pattern for processing. The dispersion of the fibre should be representative of the worst-case dispersion range given in the relevant PMD table in clause 9.2.6. The launch power at the fibre input should be kept low enough to ensure operation in the linear regime, but high enough to ensure that noise from the O/E converter does not significantly impact measurement accuracy. + +For the TDEC measurement, the optical modulation amplitude ( $OMA_{TDEC}$ ) of the signal should be determined from the regions of the optical signal where long sequences of identical symbols are present. For example, with the SSPR pattern there are sequences consisting of both 72 bit zero and one sequences. An average power level from the middle of such a sequence is taken and the $OMA_{TDEC}$ is calculated as the linear power difference between the mean 1 and 0 (see Figure 9-8). + +![Figure 9-8: Illustration of the OMA measurement. The diagram shows a digital waveform with a transition. On the left, a flat section is labeled '50 zero bits' and 'mean '0' level'. On the right, a flat section is labeled '50 one bits' and 'mean '1' level'. A vertical double-headed arrow between these two levels is labeled OMA_TDEC. A break in the waveform is indicated by '//'.](a2dcc4a0703102026ec86e82caa4985e_img.jpg) + +G.9804.3(21) + +Figure 9-8: Illustration of the OMA measurement. The diagram shows a digital waveform with a transition. On the left, a flat section is labeled '50 zero bits' and 'mean '0' level'. On the right, a flat section is labeled '50 one bits' and 'mean '1' level'. A vertical double-headed arrow between these two levels is labeled OMA\_TDEC. A break in the waveform is indicated by '//'. + +**Figure 9-8 – Illustration of the OMA measurement** + +The waveform monitoring instrument should be calibrated appropriately to determine the noise level with no optical signal applied. The idea behind TDEC is to estimate how much noise can be added mathematically to the captured waveform before reaching the reference BER. The instrument noise is effectively removed mathematically using the noise calibration step above. + +Figure 9-9 illustrates the construction of the TDEC measurement. Four vertical histograms are measured through the eye diagram, centred at 0.425 UI and 0.575 UI, and above and below $P_{th}$ (the average level). Each histogram's temporal sampling width is 0.04 UI. The vertical histogram sampling limit inside the eye is set by a level close to $P_{th}$ such that no further samples would be captured by moving this level closer to $P_{th}$ . Similarly, the vertical histogram sampling limit at the high and low levels are set outside the eye diagram such that no further samples would be captured by increasing the outer boundary of the histogram sampling window. + +The distributions of the two histograms on the left are each multiplied by Q functions, which represent an estimate of the probability of errors caused by each part of the distribution for the greatest tolerable noise that could be added by an optical channel and a receiver. The resulting distributions are integrated, and each integral is divided by the integral of the distribution it was derived from, giving two-bit error probabilities. The Q function uses a standard deviation, $\sigma_L$ , chosen so that the average of these two-bit error probabilities is the reference BER. Similarly, for the two histograms on the right, a standard deviation, $\sigma_R$ , is found. + +![Figure 9-9: Illustration of the TDEC measurement. The graph shows a waveform with two vertical bars at 0.5 ± 0.075 UI. The upper distribution is labeled f_u(y) and the lower distribution is labeled f_l(y). The threshold level is labeled P_th. The eye opening is labeled OMA. The upper and lower levels are labeled y_1 and y_0 respectively. The x-axis is labeled G.9804.3(21) and ranges from 0 to 1. The y-axis has a grid.](bafe3665fa89ba09857af5a2532c79fe_img.jpg) + +Figure 9-9: Illustration of the TDEC measurement. The graph shows a waveform with two vertical bars at 0.5 ± 0.075 UI. The upper distribution is labeled f\_u(y) and the lower distribution is labeled f\_l(y). The threshold level is labeled P\_th. The eye opening is labeled OMA. The upper and lower levels are labeled y\_1 and y\_0 respectively. The x-axis is labeled G.9804.3(21) and ranges from 0 to 1. The y-axis has a grid. + +**Figure 9-9 – Illustration of the TDEC measurement** + +The TDEC method finds a value of $\sigma_G$ such that the following equation is satisfied: + +$$\frac{1}{2} \left( \frac{\int f_u(y) Q\left(\frac{y-P_{th}}{C_{eq} \cdot \sigma_G(y)}\right) dy}{\int f_u(y) dy} \right) + \frac{1}{2} \left( \frac{\int f_l(y) Q\left(\frac{P_{th}-y}{C_{eq} \cdot \sigma_G(y)}\right) dy}{\int f_l(y) dy} \right) = \text{BER}_{\text{target}} \quad (9-3)$$ + +where + +$f_u(y)$ and $f_l(y)$ are the upper and lower distributions of the samples in the eye + +$\text{BER}_{\text{target}}$ is the reference BER + +$Q(x)$ is the area under a normal curve larger than $x$ , in this way, $Q\left(\frac{y-P_{th}}{\sigma_G}\right)$ can be regarded as the error probability when adding noise to samples with $y$ amplitude level + +$\sigma_G$ is the left or right standard deviation, $\sigma_L$ or $\sigma_R$ , given by + +$$\sigma_G(y) = \sqrt{(M^2(y)(\sigma_{0,G}^2 + S^2) - S^2)} \quad (9-4)$$ + +$$M(y) = \begin{cases} \frac{m(y-y_0)+(y_1-y)}{(y_1-y_0)} & \text{for } y \geq y_0 \\ 1 & \text{for } y < y_0 \end{cases} \quad (9-5)$$ + +$m = \frac{\sigma_1}{\sigma_0}$ , where $\sigma_0$ and $\sigma_1$ are the noise for input levels $y_0$ and $y_1$ respectively. $m$ must be set appropriately for APD receivers to $m = 1.5$ + +$C_{eq}$ is the noise enhancement factor caused by the reference equalizer, and is expressed as + +$$C_{eq} = \sqrt{\int_f \Phi(f) \times |H_{eq}(f)|^2 df} \quad (9-6)$$ + +where $\Phi(f)$ is the normalized noise spectrum obtained by filtering white noise with the reference filter. $H_{eq}(f)$ is the frequency response of the reference equalizer. + +$$\int_f \Phi(f) df = 1 \quad (9-7)$$ + +$$H_{eq}(f) = 1, \quad f = 0$$ + +The T-spaced FFE filter taps should be optimized for minimum TDEC while fixing the main FFE tap location in the middle allowing for the same amount of pre- and post-cursors. + +Once the optimal T-spaced FFE filter tap response is found, it should be up-sampled by inserting a zero tap between each of the 13 tap values to extend the frequency up to the baud rate. The reference noise and filter response integration for $C_{eq}$ should be computed from DC to 50 GHz. + +Accordingly, the noise $\sigma_{estimated\_DUT}$ that could be added by a receiver is given by, + +$$\sigma_{estimated\_DUT} = \sqrt{N^2 + S^2} \quad (9-8)$$ + +where + +$$N = \min(\sigma_{0,L}, \sigma_{0,R})$$ + +$S$ is the standard deviation of the scope noise with no input signal. + +The ideal transmitter is calculated to have a noise standard deviation $\sigma_{0,ideal}$ which can be calculated using the equation: + +$$2\text{BER}_{\text{target}} = Q\left(\frac{OMA}{2\sigma_{0,ideal}}\right) + Q\left(\frac{OMA}{2m\sigma_{0,ideal}}\right) \quad (9-9)$$ + +While there is no closed form solution to this equation, a simple numerical search can be used to estimate $\sigma_{0,ideal}$ . Finally, TDEC is calculated as: + +$$TDEC = 10 \cdot \log_{10} \left( \frac{\sigma_{0,ideal}}{\sigma_{estimated\_DUT}} \right) \quad (9-10)$$ + +Care should be taken to ensure measurement instruments follow the method described in clause 9.2.7.8.1 when measuring 50G-PON OLT transmitters, the noise enhancement factor of the equalizer ( $C_{eq}$ ) should be added into the final TDEC value together with eye closure of the test eye diagram after equalization, if the test equipment does not implement such summation function. In this case TDEC is calculated as: + +$$TDEC = 10 \cdot \log_{10} \left( C_{eq} \frac{\sigma_{0,ideal}}{\sigma_{eq}} \right) \quad (9-11)$$ + +Where $\sigma_{eq}$ is the maximum noise that could be added to a receiver without taking $C_{eq}$ into account. + +### 9.2.8 Optical path between S/R (or S/Rm) and R/S + +#### 9.2.8.1 Attenuation range + +Six classes of attenuation range are specified in clause 6.1. + +Attenuation specifications are assumed to be worst-case values at all wavelengths specified in Table 9-4a, including losses due to splices, connectors, optical attenuators (if used) or other passive optical devices, and any additional cable margin to cover allowances for: + +- 1) Future modifications to the cable configuration (additional splices, increased cable lengths, etc.); +- 2) Fibre cable performance variations due to environmental factors; and +- 3) Degradation of any connector, optical attenuators (if used) or other passive optical devices between points S and R, when provided. + +#### **9.2.8.2 Minimum optical return loss of the cable plant at point R/S including any connectors** + +Overall minimum optical return loss (ORL) specification at point R/S in the ODN is specified in Tables 9-5 to 9-8. + +Optionally, the minimum ORL specification at point R/S in the ODN is specified in Tables 9-5 to 9-8. + +NOTE – The overall reflectance at the S/R (or S/Rm) point for an ODN model is dominated by the optical connectors at the optical distribution frame (ODF). The maximum reflectance of a single discrete element within [ITU-T G.982] is $-35$ dB. The reflectance from the two ODF connectors leads to a figure of $-32$ dB. However, based on another network model, the overall reflectance may become worse than $-20$ dB. + +#### **9.2.8.3 Maximum discrete reflectance between points S and R** + +All discrete reflectances in the ODN shall be better than $-35$ dB as defined in [ITU-T G.982]. + +#### **9.2.8.4 Dispersion** + +Systems considered limited by dispersion have the maximum values of dispersion (ps/nm) specified in Tables 9-5 to 9-8. These values are consistent with the maximum TDEC and optical path penalties specified. They take into account the specified transmitter type and the fibre dispersion coefficient over the operating wavelength range. + +### **9.2.9 Receiver at S/R (or S/Rm) and R/S** + +All parameters are specified as follows, in accordance with Tables 9-5 to 9-8. + +#### **9.2.9.1 Receiver sensitivity** + +The values are specified in Tables 9-5 to 9-8. Receiver sensitivity takes into account power penalties caused by the use of a transmitter under standard operating conditions with specified values of extinction ratio and worst-case values of pulse rise and fall times, ORL at point R/S, receiver connector degradation and measurement tolerances. The receiver sensitivity does not include power penalties associated with dispersion, jitter or reflections from the optical path; these effects are specified separately in the allocation of maximum optical path penalty. + +#### **9.2.9.2 Receiver overload** + +The values are specified in Tables 9-5 to 9-8, accordingly. The receiver should have a certain robustness against increased optical power level due to start-up or potential collisions during ranging, for which the BER, specified in Tables 9-5 to 9-8, is not guaranteed. + +#### **9.2.9.3 Maximum optical path penalty** + +The receiver is required to tolerate an optical path penalty not exceeding the value. + +#### **9.2.9.4 Maximum reflectance at R/S measured at receiver wavelength** + +Reflections from equipment (ONU/OLT) back to the cable plant are specified by the maximum permissible reflectance of equipment measured at optical interfaces S/R (or S/Rm) and R/S. It shall be in accordance with Tables 9-5 to 9-8. + +#### **9.2.9.5 Differential optical path loss** + +Differential OPL means the OPL difference between the highest and lowest OPL in the same ODN. The maximum differential OPL is defined in Tables 9-5 to 9-8. + +#### **9.2.9.6 Clock extraction capability** + +NOTE – The clock of the upstream transmission signal is extracted rapidly from several alternating bits in the preamble. The clock extracted from the preamble is maintained at least during the reception of the signal from + +the delimiter to the end of the upstream assigned burst, or is continuously extracted from the signal after the preamble during the reception of the assigned burst. + +#### 9.2.9.7 Jitter performance + +This clause defines jitter requirements for optical interfaces of 50G-PON. + +##### 9.2.9.7.1 Jitter transfer + +The jitter transfer specification applies only to the ONU. + +The jitter transfer function is defined as: + +$$jitter\ transfer = 20 \log_{10} \left[ \frac{jitter\ on\ upstream\ signal\ UI}{jitter\ on\ downstream\ signal\ UI} \times \frac{down\ stream\ bit\ rate}{upstream\ bit\ rate} \right]$$ + +The jitter transfer function of an ONU shall be under the curve given in Figure 9-10, when input sinusoidal jitter up to the mask level in Figure 9-11 is applied, with the parameters specified in Figure 9-10 for each line rate. + +![Figure 9-10: Jitter transfer mask for ONU. The figure consists of a graph and a table. The graph shows Jitter gain on the y-axis and Frequency on the x-axis. The gain is constant at P from f_L to f_C, then decreases with a slope of -20 dB/dec until f_H. The table provides the values for f_L, f_C, f_H, and P for three upstream line rates.](30ffebf544a71997b61e5f4be3d321ef_img.jpg) + +| Upstream line rate [Gbit/s] | $f_L$ [kHz] | $f_C$ [kHz] | $f_H$ [kHz] | P [dB] | +|-----------------------------|-------------|-------------|-------------|--------| +| 12.4416 | 10 | 4000 | 100 000 | 0.1 | +| 24.8832 | 10 | 4000 | 200 000 | 0.1 | +| 49.7664 | 10 | 4000 | 400 000 | 0.1 | + +Figure 9-10: Jitter transfer mask for ONU. The figure consists of a graph and a table. The graph shows Jitter gain on the y-axis and Frequency on the x-axis. The gain is constant at P from f\_L to f\_C, then decreases with a slope of -20 dB/dec until f\_H. The table provides the values for f\_L, f\_C, f\_H, and P for three upstream line rates. + +G.9804.3(21) + +**Figure 9-10 – Jitter transfer mask for ONU** + +NOTE – The jitter gain mask in Figure 9-10 defines the value of transferred jitter that on frequencies above 100, 200 or 400 MHz is negligible relative to the expected generation jitter (see Table 9-11) and therefore may be completely masked by the generation jitter in the measurement set-up. + +![Figure 9-11: Sinusoidal jitter mask for jitter transfer evaluation. The graph shows input jitter amplitude on the y-axis and frequency on the x-axis. The amplitude is constant at A3 from 0 to f2, then decreases with a slope of -20 dB/dec until it reaches A4 at f3, where it remains constant. The table below provides the values for these parameters.](24b549c0c4b79c515b244625cf4f4978_img.jpg) + +| Downstream line rate [Gbit/s] | A 3 [UI p-p ] | A 4 [UI p-p ] | f 2 [kHz] | f 3 [kHz] | +|-------------------------------|-------------------------------------|-------------------------------------|----------------------|----------------------| +| 49.7664 | 0.75 | 0.075 | 400 | 4000 | + +G.9804.3(21) + +Figure 9-11: Sinusoidal jitter mask for jitter transfer evaluation. The graph shows input jitter amplitude on the y-axis and frequency on the x-axis. The amplitude is constant at A3 from 0 to f2, then decreases with a slope of -20 dB/dec until it reaches A4 at f3, where it remains constant. The table below provides the values for these parameters. + +**Figure 9-11 – Sinusoidal jitter mask for jitter transfer evaluation** + +##### 9.2.9.7.2 Jitter tolerance + +Jitter tolerance is defined as the peak-to-peak amplitude of sinusoidal jitter applied on the input of 50G-PON signal that causes a 1 dB optical power penalty at the optical equipment. Note that it is a stress test to ensure that no additional penalty is incurred under typical operating conditions. + +The ONU shall tolerate, as a minimum, the input jitter applied according to the mask in Figure 9-12, with the parameters specified in that figure for the downstream line rate. The OLT should tolerate, as a minimum, the input jitter applied according to the mask in Figure 9-12, with the parameters specified in that figure for the upstream line rate. The jitter tolerance specification for the OLT is informative as it can only be measured in a setting that permits continuous operation of the upstream. + +![Figure 9-12: Jitter tolerance mask. The graph shows input jitter amplitude on the y-axis and frequency on the x-axis. The amplitude is constant at A2 from 0 to f0, then decreases with a slope of -20 dB/dec until it reaches A1 at ft, where it remains constant. The table below provides the values for these parameters for different line rates.](a8f5e96261c2ea20a0f83f121d8fcbcb_img.jpg) + +| Line rate [Gbit/s] | f 0 [kHz] | f t [kHz] | A 1 [UI p-p ] | A 2 [UI p-p ] | +|--------------------|----------------------|----------------------|-------------------------------------|-------------------------------------| +| 12.4416 | 400 | 4000 | 0.075 | 0.75 | +| 24.8832 | 400 | 4000 | 0.075 | 0.75 | +| 49.7664 | 400 | 4000 | 0.075 | 0.75 | + +G.9804.3(21) + +Figure 9-12: Jitter tolerance mask. The graph shows input jitter amplitude on the y-axis and frequency on the x-axis. The amplitude is constant at A2 from 0 to f0, then decreases with a slope of -20 dB/dec until it reaches A1 at ft, where it remains constant. The table below provides the values for these parameters for different line rates. + +**Figure 9-12 – Jitter tolerance mask** + +NOTE – The values of A1 and A2 in Figure 9-12 assume that the generated jitter (see Table 9-11) is not dominated by a single or a few strong sinusoidal components. + +##### 9.2.9.7.3 Jitter generation + +An ONU shall not generate a peak-to-peak jitter amplitude more than that shown in Table 9-11 at line rates of 12.4416 Gbit/s, 24.8832 Gbit/s, and 49.7664 Gbit/s, with no jitter applied to the downstream input and with a measurement bandwidth as specified in Table 9-11. An OLT shall not generate a + +peak-to-peak jitter amplitude more than that shown in Table 9-11 at a line rate of 49.7664 Gbit/s, with no jitter applied to its timing reference input and with a measurement bandwidth as specified in Table 9-11. + +**Table 9-11 – Jitter generation requirements** + +| Line rate (Gbit/s) | Measurement band
(-3 dB frequencies)
(Note 1) | | Peak-to-peak amplitude
(UI)
(Note 2) | +|--------------------|-----------------------------------------------------|------------------------------|--------------------------------------------| +| | High-pass
(kHz) | Low-pass (MHz)
-60 dB/dec | | +| 12.4416 | 10 | 100 | 0.5 | +| | 25 | 100 | 0.3 | +| | 4000 | 100 | 0.1 | +| 24.8832 | 10 | 200 | 0.7 | +| | 50 | 200 | 0.3 | +| | 4000 | 200 | 0.1 | +| 49.7664 | 10 | 400 | 1.0 | +| | 100 | 400 | 0.3 | +| | 4000 | 400 | 0.15 | + +NOTE 1 – The high-pass and low-pass measurement filter transfer functions are defined in clause 5 of [b-ITU-T G.825]. + +NOTE 2 – The measurement time and pass/fail criteria are defined in clause 5 of [b-ITU-T G.825]. + +#### 9.2.9.8 Consecutive identical digit (CID) immunity + +The OLT and the ONU shall have a consecutive identical digit (CID) immunity as specified in Tables 9-5 to 9-8. + +#### 9.2.9.9 Receiver tolerance to reflected power + +The receiver tolerance to reflected power is the allowable ratio of optical input average power of S/R (or S/Rm) and R/S to reflected optical average power when multiple reflections are regarded as a noise light at the optical interfaces S/R (or S/Rm) and R/S, respectively. + +The receiver tolerance to reflected power is defined at minimum receiver sensitivity. + +#### 9.2.9.10 Transmission quality and error performance + +To avoid system down time or failures, the frame structure should be robust in the presence of transmission BER up to the values defined in Tables 9-5 to 9-8. + +The average BER on individual links across the entire PON system will typically be lower than the values defined in Tables 9-5 to 9-8. Optical components should provide BER better than the values defined in Tables 9-5 to 9-8 when conditions allow. + +# 10 X/S tolerance of 50G-PON ONU and OLT + +The minimum optical sensitivity of a 50G-PON ONU must be met in the presence of interference signals. Interference signals are caused by other services such as legacy PON and/or video signals specified in clause 6.3 of [ITU-T G.9804.1]. To minimize the effect of interference signals, 50G-PON ONUs need to isolate them using an appropriate wavelength blocking filter (WBF) and WDM filter. This Recommendation does not specify the isolation characteristics of the WBF and WDM filters directly, but specifies the X/S tolerance of the 50G-PON ONU. Here, S is the optical power of the + +50G-PON signal, and X is that of the interference signal(s). Both are measured at the ONU reference point R/S, corresponding to the ONU reference point IF50GTDM specified in clause 6.3 in [ITU-T G.9804.1]. + +The interference signal format for measuring X/S tolerance is a NRZ pseudo-random code with the same line rate as the 50G-PON downstream signal or a lower line rate within the bandwidth of the 50G-PON receiver. + +## 10.1 Versatile WDM configuration + +This clause describes the X/S tolerance of 50G-PON ONUs and OLT. This tolerance can be used to design a variety of WDM configurations at the ONU. This clause specifies the X/S tolerance mask that should not cause the 50G-PON receiver to fail to meet its sensitivity requirements. Implementers need to specify the isolation characteristics of the WBF and WDM filters to obtain enough isolation of the interference signal(s). This allows the 50G-PON sensitivity requirement to be met in the presence of this level of interference. + +For the basic wavelength set, the wavelengths and total optical launch power of additional services must fall beneath the mask of Figure 10-1 to allow coexistence with 50G-PON. + +![Figure 10-1: X/S tolerance mask for 50G-PON ONU (Versatile WDM configuration). The figure includes a graph of X/S (dB) vs Wavelength (nm) and two tables providing class and wavelength details.](fd38170a3981416226ab91f7437ba821_img.jpg) + +The graph shows the X/S tolerance mask. The vertical axis is X/S (dB) with levels y1 and y2. The horizontal axis is Wavelength (nm) with markers λ3, λ4', λ4, 1340, 1344, λ5, λ5', and λ6. A '50G PON band' is indicated between 1340 nm and 1344 nm. The mask consists of two hatched regions: one on the left from λ3 to λ4 with a slope between λ4' and λ4, and one on the right from λ5 to λ6 with a slope between λ5 and λ5'. The levels y1 and y2 are indicated by horizontal dashed lines. + +| Class | y1 (dB) | y2 (dB) | +|--------|---------|---------| +| N1, C+ | 3 | 18.5 | + + + +| Wavelength (nm) | λ3 | λ4' | λ4 | λ5 | λ5' | λ6' | +|-----------------|------|------|------|------|------|------| +| | 1260 | 1290 | 1330 | 1356 | 1400 | 1675 | + +S: Received power of 50G-PON band. +X: Maximum total power of additional services received in the blocking wavelength range. +X/S: The mask (hatched area) should not cause the 50G-PON receiver to fail to meet its sensitivity requirements. + +Figure 10-1: X/S tolerance mask for 50G-PON ONU (Versatile WDM configuration). The figure includes a graph of X/S (dB) vs Wavelength (nm) and two tables providing class and wavelength details. + +**Figure 10-1 – X/S tolerance mask for 50G-PON ONU (Versatile WDM configuration)** + +X/S tolerance of 50G-PON OLT can be used to design a variety of WDM configurations at the OLT (see Figures 10-2 to 10-4). This clause specifies the X/S tolerance mask that should not cause the 50G-PON OLT receiver to fail to meet its sensitivity requirements. Implementers need to specify the isolation characteristics of the WBF and WDM filters to obtain sufficient isolation of the interference signal(s) in the implementation. This allows the 50G-PON OLT sensitivity requirement to be met in the presence of this level of interference. + +![Figure 10-2: X/S tolerance mask for upstream wavelength option 1 50G-PON OLT. The graph shows X/S (dB) on the y-axis and Wavelength (nm) on the x-axis. A rectangular box labeled 'Option 1' is between 1260 nm and 1280 nm. A hatched rectangular area is between 1290 nm and 1675 nm. A dashed horizontal line labeled 'Y' extends from the top of the 'Option 1' box to the start of the hatched area. A table below the graph shows Class N1, C+ with Y(dB) = -6. Reference G.9804.3(21) is noted.](f899c67120dc04a5e5a5c2d94461a077_img.jpg) + +| Class | Y(dB) | +|--------|-------| +| N1, C+ | -6 | + +G.9804.3(21) + +Figure 10-2: X/S tolerance mask for upstream wavelength option 1 50G-PON OLT. The graph shows X/S (dB) on the y-axis and Wavelength (nm) on the x-axis. A rectangular box labeled 'Option 1' is between 1260 nm and 1280 nm. A hatched rectangular area is between 1290 nm and 1675 nm. A dashed horizontal line labeled 'Y' extends from the top of the 'Option 1' box to the start of the hatched area. A table below the graph shows Class N1, C+ with Y(dB) = -6. Reference G.9804.3(21) is noted. + +- S: Received power of basic band. +- X: Maximum total power of additional services received in the blocking wavelength range. +- X/S: The mask (hatched area) should not cause the 50G-PON receiver to fail to meet its sensitivity requirements. + +**Figure 10-2 – X/S tolerance mask for upstream wavelength option 1 50G-PON OLT** + +![Figure 10-3: X/S tolerance mask for upstream wavelength option 2 (Wideband) 50G-PON OLT. The graph shows X/S (dB) on the y-axis and Wavelength (nm) on the x-axis. A rectangular box labeled 'Optional 2 (Wide)' is between 1290 nm and 1310 nm. Hatched rectangular areas are between 1260 nm and 1280 nm, and between 1340 nm and 1675 nm. A dashed horizontal line labeled 'Y' extends from the top of the 'Optional 2 (Wide)' box to the hatched areas. A table below the graph shows Class N1, C+ with Y(dB) = -5. Reference G.9804.3(21) is noted.](771c18f874d31c59c3b8c4e247be16ca_img.jpg) + +| Class | Y(dB) | +|--------|-------| +| N1, C+ | -5 | + +G.9804.3(21) + +Figure 10-3: X/S tolerance mask for upstream wavelength option 2 (Wideband) 50G-PON OLT. The graph shows X/S (dB) on the y-axis and Wavelength (nm) on the x-axis. A rectangular box labeled 'Optional 2 (Wide)' is between 1290 nm and 1310 nm. Hatched rectangular areas are between 1260 nm and 1280 nm, and between 1340 nm and 1675 nm. A dashed horizontal line labeled 'Y' extends from the top of the 'Optional 2 (Wide)' box to the hatched areas. A table below the graph shows Class N1, C+ with Y(dB) = -5. Reference G.9804.3(21) is noted. + +- S: Received power of basic band. +- X: Maximum total power of additional services received in the blocking wavelength range. +- X/S: The mask (hatched area) should not cause the 50G-PON receiver to fail to meet its sensitivity requirements. + +**Figure 10-3 – X/S tolerance mask for upstream wavelength option 2 (Wideband) 50G-PON OLT** + +![Figure 10-4: X/S tolerance mask for upstream wavelength option 2 (Narrowband) 50G-PON OLT. The graph shows a power mask with a dashed line at Y dB and hatched blocking regions. A table below defines Class N1, C+ with Y = -5 dB.](bd4a5cf22b8d8060c4bf3577beb30df8_img.jpg) + +The figure illustrates the X/S tolerance mask for upstream wavelength option 2 (Narrowband) 50G-PON OLT. The x-axis represents Wavelength (nm) with markers at 1260, 1280, 1298, 1302, 1340, and 1675. The y-axis represents X/S (dB) with a marker Y. A dashed horizontal line is drawn at Y dB. Two hatched rectangular regions are shown: one from 1260 nm to 1280 nm, and another from 1340 nm to 1675 nm. A central box labeled 'Optional 2 (Narrow)' spans from 1298 nm to 1302 nm. Below the graph is a table: + +| Class | Y(dB) | +|--------|-------| +| N1, C+ | -5 | + +G.9804.3(21) + +Figure 10-4: X/S tolerance mask for upstream wavelength option 2 (Narrowband) 50G-PON OLT. The graph shows a power mask with a dashed line at Y dB and hatched blocking regions. A table below defines Class N1, C+ with Y = -5 dB. + +- S: Received power of basic band. +X: Maximum total power of additional services received in the blocking wavelength range. +X/S: The mask (hatched area) should not cause the 50G-PON receiver to fail to meet its sensitivity requirements. + +**Figure 10-4 – X/S tolerance mask for upstream wavelength option 2 (Narrowband) 50G-PON OLT** + +# 11 Upstream physical layer overhead + +The 50G-PON frame structure is described in [ITU-T G.9804.2], which is devoted to the specification of the TC layer. However, upstream burst transmissions must be preceded by suitable physical layer overhead time ( $T_{plo}$ ), which is used to accommodate several physical processes. Table 11-1 shows the length of the physical layer overhead for the upstream line rate specified in this Recommendation. The OLT takes its actual overhead time requirements into account when computing the BWmap. + +**Table 11-1 – Objective 50G-PON upstream physical layer overhead** + +| Upstream line rate | Overhead bits | +|--------------------|---------------| +| 12.4416 Gbit/s | 2560 | +| 24.8832 Gbit/s | 5120 | +| 49.7664 Gbit/s | FFS | + +Moreover, Appendix III provides information on the physical processes that have to be performed during the $T_{plo}$ , and some guidelines for allocation of $T_{plo}$ . Appendix III also indicates the potential worst-case $T_{plo}$ values. + +## Appendix I + +### Relationship between OMA, penalty, extinction ratio and average power + +(This appendix does not form an integral part of this Recommendation.) + +The transmitter characteristics are measured by the transmitter extinction ratio, its average power and the penalty after fibre transmission. In this Recommendation, OPP is used as the ONU transmitter penalty parameter for 12.4416 Gbit/s and 24.8832 Gbit/s upstream, and TDEC is used as the OLT transmitter penalty parameter for downstream. This appendix is intended to describe how optical modulation amplitude (OMA), ER, (OPP or TDEC) penalty and average power ( $P_{\text{mean}}$ ) are related to one other. + +Clause 58.7.6 of [IEEE 802.3] defines the transmitter parameter, OMA, whose relationship with averaged launch power and extinction ratio is as follows: + +$$OMA = P_1 - P_0 \quad (\text{I.1})$$ + +$$ER = \frac{P_1}{P_0} \quad (\text{I.2})$$ + +$$P_{\text{mean}} \approx \frac{P_1 + P_0}{2} \quad (\text{I.3})$$ + +$$OMA \approx 2 \times P_{\text{mean}} \times \frac{ER-1}{ER+1} \quad (\text{I.4})$$ + +Where $P_1$ and $P_0$ are the mean one and zero level powers of the NRZ signal, respectively. + +NOTE – The $P_{\text{mean}}$ and $ER$ are all in linear units in the above equations. OMA and launch power should be expressed in watt. + +For a compliant transmitter, the relationship between OMA, $ER$ and average power can be derived based on equations (I.1) to (I.4). + +If the 24.8832 Gbit/s upstream ONU transmitter specification defined in Table 9-5 is taken as an example, the minimum "OMA minus OPP" is 4.7 dBm and 4.5 dBm for $ER < 6$ dB and $ER \geq 6$ dB, respectively. The minimum extinction ratio is 5 dB. + +| ODN class | | N1 | C+ | +|-------------------------------------|-----|-----|-----| +| Launch power in OMA minus OPP (min) | | | | +| – When $ER < 6$ dB | dBm | 4.7 | 4.7 | +| – When $ER \geq 6$ dB | | 4.5 | 4.5 | +| Minimum extinction ratio | dB | 5 | | + +When the OPP is 0.5 dB, this will require 5.2 dBm minimum launch OMA for $ER < 6$ dB, and require 5 dBm minimal launch OMA for $ER \geq 6$ dB. Based on the above equations (I.1) to (I.4), the following example with lower boundaries of mean launch power and $ER$ pairs can be derived as shown in Table I.1: + +**Table I.1 – Lower boundary mean launch power and ER pairs of the 24.8832 Gbit/s upstream ONU transmitter admissible region** + +| Parameters | Unit | $(\bar{P}_1, ER_1)$ | $(\bar{P}'_2, ER'_2)$ | $(\bar{P}_2, ER_2)$ | $(\bar{P}_3, ER_3)$ | $(\bar{P}_5, ER_5)$ | +|---------------------------|------|---------------------|-----------------------|---------------------|---------------------|---------------------| +| Mean launch optical power | dBm | 5.0 | 4.4 | 4.2 | 3.7 | 3.4 | +| ER | dB | 5 | 5.99\dot{9} | 6 | 7 | 8 | +| OMA | dBm | 5.2 | | 5.0 | | | +| OPP | dB | 0.5 | | | | | + +The parameters of the transmitter jointly specified by $\bar{P}$ and $ER$ shall lie within an admissible region (shown as a hatched area in Figure I.1). + +![Figure I.1: A line graph showing Average Tx power (dBm) on the y-axis from 2.0 to 10.0 and ER (dB) on the x-axis from 4.0 to 8.0. A hatched region represents the admissible transmitter power. The lower boundary of this region is defined by a series of points: (5.0, 5.0) labeled (P1, ER1), (6.0, 4.2) labeled (P2, ER2), (7.0, 3.7) labeled (P3, ER3), and (8.0, 3.4) labeled (P5, ER5). There is also a point (P'2, ER'2) at (5.999, 4.4) and a point (P4, ER4) indicated on the line. The region extends vertically upwards from this boundary to 9.0 dBm and horizontally to the right from ER=5.0.](516d9f1866cc2e359a35fb1d8c046454_img.jpg) + +Mean launch power vs ER 24.88 Gb/s upstream (0.5 dB OPP) + +| ER (dB) | Average Tx power (dBm) | Point Label | +|-------------|------------------------|-----------------------| +| 5.0 | 5.0 | $(\bar{P}_1, ER_1)$ | +| 5.99\dot{9} | 4.4 | $(\bar{P}'_2, ER'_2)$ | +| 6.0 | 4.2 | $(\bar{P}_2, ER_2)$ | +| 7.0 | 3.7 | $(\bar{P}_3, ER_3)$ | +| 8.0 | 3.4 | $(\bar{P}_5, ER_5)$ | + +G.9804.3(21) + +Figure I.1: A line graph showing Average Tx power (dBm) on the y-axis from 2.0 to 10.0 and ER (dB) on the x-axis from 4.0 to 8.0. A hatched region represents the admissible transmitter power. The lower boundary of this region is defined by a series of points: (5.0, 5.0) labeled (P1, ER1), (6.0, 4.2) labeled (P2, ER2), (7.0, 3.7) labeled (P3, ER3), and (8.0, 3.4) labeled (P5, ER5). There is also a point (P'2, ER'2) at (5.999, 4.4) and a point (P4, ER4) indicated on the line. The region extends vertically upwards from this boundary to 9.0 dBm and horizontally to the right from ER=5.0. + +**Figure I.1 – Transmitter power and ER admissible region (hatched) for 24.8832 Gbit/s upstream when OPP = 0.5dB** + +Arbitrary mean launch power and $ER$ pairs may be generated based on equations (I.1) to (I.4). + +When the OPP is more than 0.5 dB, the minimal launch power requirement should be increased accordingly to maintain the same "OMA minus penalty" requirement. + +## **Appendix II** + +### **Physical layer measurements required to support optical layer supervision** + +(This appendix does not form an integral part of this Recommendation.) + +See Appendix II of [ITU-T G.989.2]. + +## Appendix III + +### Allocation of the physical layer overhead time + +(This appendix does not form an integral part of this Recommendation.) + +The physical layer overhead time ( $T_{plo}$ ) is used to accommodate five physical processes in the PON. These are: laser on/off time, timing drift tolerance, level recovery, clock recovery and start of burst delineation. The exact division of the physical layer time to all these functions is determined partly by constraint equations and partly by implementation choices. This appendix reviews the constraints that the OLT must comply with, and suggests values for the discretionary values. + +$T_{plo}$ includes three sections with respect to what ONU data pattern is transmitted. For simplicity, these sections can be referred to as the guard time ( $T_g$ ), the preamble time ( $T_p$ ) and the delimiter time ( $T_d$ ). It thus follows that $T_{plo} \geq T_g + T_p + T_d$ . During $T_g$ , the ONU will transmit no more power than the nominal zero level. During $T_p$ , the ONU will transmit a preamble pattern that provides the desired transition density and signal pattern for fast level adjustment, clock recovery and optional equalization functions. Lastly, during $T_d$ , the ONU will transmit a special data pattern, a delimiter, with optimal autocorrelation properties that enable the OLT to find the beginning of the burst payload. Table III.2 gives recommended values for $T_g$ , $T_p$ , $T_d$ and $T_{plo}$ . Figure III.1 shows the timing relationship between the various physical layer overhead times. + +![Timing diagram showing the relationship between physical layer overhead times (T_plo, T_u, T_on, T_p, T_d, T_off, T_g) for two bursts (ONU i and ONU j).](9a14684f8ae1345c6efea6f5994c730c_img.jpg) + +The diagram illustrates the timing relationship between two consecutive bursts, 'End of previous burst, ONU i' and 'Beginning of body, next burst, ONU j'. The total physical layer overhead time $T_{plo}$ is shown as a horizontal double-headed arrow spanning from the start of the guard time $T_g$ to the start of the delimiter time $T_d$ . The guard time $T_g$ is the first segment, starting from the end of the previous burst. It is followed by the preamble time $T_p$ and the delimiter time $T_d$ . The timing uncertainty $T_u$ is shown as a segment within the guard time $T_g$ . The laser on time $T_{on}$ and laser off time $T_{off}$ are also indicated. The diagram is labeled G.9804.3(21). + +Timing diagram showing the relationship between physical layer overhead times (T\_plo, T\_u, T\_on, T\_p, T\_d, T\_off, T\_g) for two bursts (ONU i and ONU j). + +**Figure III.1 – Timing relationship between the various physical layer overhead times** + +An additional parameter of the control logic on the PON is the total peak-to-peak timing uncertainty ( $T_u$ ). This uncertainty arises from variations of the time of flight caused by the fibre and component variations with temperature and other environmental factors. + +The constraint conditions with which the OLT must comply are then: + +$$T_g > T_{on} + T_u, \text{ and}$$ + +$$T_g > T_{off} + T_u$$ + +These conditions can be explained as follows. The first condition makes sure that the following burst's laser on ramp-up does not fall on top of the last burst's data. The second condition makes sure that the last burst's laser off tail-off does not fall on top of the following burst's preamble. + +$T_p$ must be sufficient for the physical layer to recover the signal level (essentially, setting the decision threshold) and the signal clock phase and allow for equalizer convergence, should equalization be necessary. There are many diverse design approaches to the first two problems, each with its own benefits and costs. Some designs are very fast, but require an external trigger signal and produce sub-optimal error performance. Other designs are slower, but do not require a reset signal and produce bit errors that are normally distributed. In addition, each of these designs may have special requirements on the data pattern used for the preamble. Some designs prefer a maximum transition density pattern, while others prefer a pattern with a balance of transitions and controlled runs of identical digits. + +Since the design is up to the OLT implementer, the OLT configures the details of the preamble that is transmitted by the ONU. This is part of the burst profile discussion below. + +$T_a$ must be long enough to provide a robust delimiter function in the face of bit errors. The error resistance of the delimiter depends on the exact implementation of the pattern correlator, but a simple approximate relationship between the number of bits in the delimiter ( $N$ ) and the number of bit errors tolerated ( $E$ ) is as expressed in equation (III.1): + +$$E = \lfloor N/4 \rfloor - 1, \quad (\text{III.1})$$ + +where $\lfloor \cdot \rfloor$ denotes a floor function. Equation (III.1) has been empirically verified by a numerical search of all delimiters of sizes with 32 and 64 bits. This search was performed under the assumption that the preamble pattern was a '1010' repeating pattern, and that the delimiter had an equal number of zeroes and ones. The Hamming distance ( $D$ ) of the best delimiter from all shifted patterns of itself and the preamble was found to be $D = \lfloor N/2 \rfloor - 1$ , yielding the error tolerance shown. + +Given a certain bit error ratio ( $BER$ ), the probability of a severely errored burst ( $P_{seb}$ ) is given by: + +$$P_{seb} = \binom{N}{E+1} BER^{E+1} \quad (\text{III.2})$$ + +Substituting equation (III.1) into equation (III.2), the resultant $P_{seb}$ is given by equation (III.3): + +$$P_{seb} = \binom{N}{\lfloor N/4 \rfloor} BER^{\lfloor N/4 \rfloor} \quad (\text{III.3})$$ + +Values of $P_{seb}$ for various bit error ratios and delimiter lengths are given in Table III.1. The choice of delimiter length and pattern is made by the OLT as part of the burst profile. + +**Table III.1 – Probability of a severely errored burst as a function of bit error ratio and delimiter length** + +| Delimiter length ( $N$ ) | Probability of a severely errored burst ( $P_{seb}$ ) | | | +|--------------------------|-------------------------------------------------------|----------------------------|----------------------------| +| | $BER = 2.0 \times 10^{-2}$ | $BER = 1.0 \times 10^{-2}$ | $BER = 5.0 \times 10^{-3}$ | +| 32 | $2.7 \times 10^{-7}$ | $1.1 \times 10^{-9}$ | $4.1 \times 10^{-12}$ | +| 64 | $3.2 \times 10^{-13}$ | $4.9 \times 10^{-18}$ | $7.5 \times 10^{-23}$ | + +With these considerations taken into account, the worst-case and objective allocations of the physical layer overhead are given in Table III.2. This table also lists the values for the ONU transmitter enable time and transmitter disable time, and the total physical layer overhead time for reference. The worst-case values are intended to provide a reasonable bound for easy implementation, and the objective values are intended to be the design target for more efficient implementation with optimized components. These values are for a simple ODN without reach extenders. Reach extenders may require their own guard and preamble time allowances, making the total overhead larger. The values in nanoseconds are for information only. + +**Table III.2 – Recommended allocation +of burst mode overhead time for 50G-PON OLT functions** + +| | Transmitter enable time | Transmitter disable time | Total time, $T_{plo}$ | Guard time, $T_g$ | Preamble time, $T_p$ | Delimiter time, $T_d$ | +|-------------------------------------------|-------------------------|--------------------------|-----------------------|-------------------|----------------------|-----------------------| +| 12.4416 Gbit/s
Worst case in bits (ns) | 1600
(128.6) | 1600
(128.6) | 10 240
(823.1) | 2560
(205.8) | 7600
(610.9) | 64
(5.14) | +| 12.4416 Gbit/s
Objective in bits (ns) | 320
(25.7) | 320
(25.7) | 2560
(205.8) | 640
(51.4) | 1856
(149.2) | 64
(5.14) | +| 24.8832 Gbit/s
Worst case in bits (ns) | 3200
(128.6) | 3200
(128.6) | 20 480
(823.1) | 5120
(205.8) | 15 200
(610.9) | 64
(2.57) | +| 24.8832 Gbit/s
Objective in bits (ns) | 640
(25.7) | 640
(25.7) | 5120
(205.8) | 1280
(51.4) | 3776
(151.75) | 64
(2.57) | +| 49.7664 Gbit/s
Worst case in bits (ns) | FFS | FFS | FFS | FFS | FFS | FFS | +| 49.7664 Gbit/s
Objective in bits (ns) | FFS | FFS | FFS | FFS | FFS | FFS | + +In addition to the design dependent aspects of the burst overhead, there can be operationally dependent factors. For example, detecting an ONU's ranging burst is a more difficult problem than receiving an ONU's regular transmission. As another example, the received power for some ONUs may be higher and therefore easier to detect, eliminating the need for FEC. For these reasons, the OLT may request different burst profiles depending on the context. + +The concept of a burst profile captures all the aspects of burst overhead control. A burst profile specifies the preamble pattern and length, the delimiter pattern and length, and whether FEC parity should be sent. The OLT establishes one or more burst profiles, and then requests a particular burst profile for each burst transmission. + +The OLT has considerable latitude in setting up the profiles, because the OLT's burst receiver is sensitive to the profile parameters. Therefore, the OLT should use profiles that ensure adequate response in its burst mode receiver. However, some basic requirements from the ONU side must be met. Namely, the preamble and delimiter patterns should be balanced, and they should have a reasonable transition density. If not, the ONU transmitter driver circuitry may be adversely affected. Also note that the preamble and delimiter patterns could differ in each profile, and this difference could be used by the OLT receiver as an in-band indication of the format of each burst (e.g., FEC active or not). + +The details of distributing the burst profiles and signalling their use are described in [ITU-T G.9804.2] Common Transmission Convergence Layer Specification. + +## Appendix IV + +### Relationship among optical interface parameters for 49.7664 Gbit/s downstream + +(This appendix does not form an integral part of this Recommendation.) + +The relationship between certain optical interface parameters for 49.7664 Gbit/s downstream is described below. We use the following notations: + +- $P_{OMA-TDEC}$ is the 'minimum launch power in OMA minus TDEC' in dBm specified in Table 9-5. +- $S_{OMA}$ is the 'OMA sensitivity at BER reference level' in dBm specified in Table 9-5. It is based on a transmitter with a $TEC_{ref} = 1.5$ dB. +- $R(TDEC)_{OMA}$ is the OMA sensitivity at BER reference level in dBm when receiving a signal with a given TDEC. This parameter is expressed as an equation in Table 9-5; it is related to $S_{OMA}$ as explained below (also see Note 9 of Table 9-5 and Figure 9-1). +- $OPL_{max}$ is the maximum optical path loss in dB for the specified ODN class (see Table 6-1 and Table 6-2). +- $TEC_{ref}$ is the transmitter eye closure of the transmitter used to determine the ONU Rx sensitivity in back to back ( $S_{OMA}$ ). It is 1.5 dB. +- $P(TDEC)_{OMA}$ is the minimum required launch OMA from an OLT Tx with a certain TDEC. +- TDEC is a value in dB used to determine $P(TDEC)_{OMA}$ and $R(TDEC)_{OMA}$ . +- $TDEC_{DUT}$ is the actual TDEC value in dB of a particular OLT transmitter. +- $TDEC_0$ is the lowest TDEC considered for an OLT transmitter. A value of $TDEC_0 = 2.0$ dB is used for the specifications in Table 9-5 (see Note below). +- $TDEC_{max}$ is the highest TDEC for an OLT transmitter. A value of $TDEC_{max} = 5.0$ dB is used for the specifications in Table 9-5. + +TDEC is given by, + +$$TDEC = \max(TDEC_0, TDEC_{DUT}) \text{ for } TDEC_{DUT} \leq TDEC_{max}$$ + +$$P(TDEC)_{OMA} \text{ is given by } P(TDEC)_{OMA} = P_{OMA-TDEC} + TDEC$$ + +From Note 11 in Table 9-5, + +$$R(TDEC)_{OMA} \leq \max(S_{OMA} - TEC_{ref} + TDEC_0, S_{OMA} - TEC_{ref} + TDEC)$$ + +In the worst case for $R(TDEC)_{OMA}$ (i.e., when equality is achieved in the above relation), + +$$P(TDEC)_{OMA} = R(TDEC)_{OMA} + OPL_{max}$$ + +Mean power values for the OLT transmitter and ONU receiver specifications are derived from the OMA values assuming $ER = 7$ dB. They are indicated in Table 9-5 to aid in-service troubleshooting operations with optical power meters. + +NOTE – The derivation of the value of $TDEC_0 = 2.0$ dB was from an assumption of a hypothetical full bandwidth OLT transmitter with a $TEC = 1.5$ dB and allowing for 0.5 dB when adding fibre impairments. + +## Bibliography + +- [b-ITU-T G.810] Recommendation ITU-T G.810 (1996), *Definitions and terminology for synchronization networks*. +- [ITU T G.825] Recommendation ITU-T G.825 (2000), *The control of jitter and wander within digital networks which are based on the synchronous digital hierarchy (SDH)*. +- [b-ITU-T G.Sup39] Recommendation ITU-T G.Sup39 (2016), *Optical system design and engineering considerations*. +- [b-OIF] Optical Internetworking Forum (2017), *Common Electrical I/O (CEI) - Electrical and Jitter Interoperability agreements for 6G+ bps, 11G+ bps, 25G+ bps I/O and 56G+ bps, IA # OIF-CEI-04.0*. <> + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.981-199401-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/G/T-REC-G.981-199401-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..845a7b96264588e7d5a7743cfb989d6ee1db9b28 --- /dev/null +++ b/marked/G/T-REC-G.981-199401-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:3c9dc466b2bbc4e2f654ecfc9516f595306f5c18389d50c56d96caf557d5a74f +size 8281 diff --git a/marked/G/T-REC-G.981-199401-I_PDF-E/547f726730e589392f239257a833ede3_img.jpg b/marked/G/T-REC-G.981-199401-I_PDF-E/547f726730e589392f239257a833ede3_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..a5616353763f999efeecd57459a44833b191c7ea --- /dev/null +++ b/marked/G/T-REC-G.981-199401-I_PDF-E/547f726730e589392f239257a833ede3_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:2d525946ed02d62645fa1df78ffeeffa390f6efdc649c4c831e6c34fe8de6485 +size 39693 diff --git a/marked/G/T-REC-G.981-199401-I_PDF-E/562f471e8153729557e6a4ee6343c32c_img.jpg b/marked/G/T-REC-G.981-199401-I_PDF-E/562f471e8153729557e6a4ee6343c32c_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..dc55f95aa383a987ac0ebd11c1528739f459cefb --- /dev/null +++ b/marked/G/T-REC-G.981-199401-I_PDF-E/562f471e8153729557e6a4ee6343c32c_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:c130e2de2bc4b8d19f6afc2908e306bc163adc2fd26e405cce51ce74dc272180 +size 11583 diff --git a/marked/G/T-REC-G.981-199401-I_PDF-E/d0abac95583b52a3b35f74a215567334_img.jpg b/marked/G/T-REC-G.981-199401-I_PDF-E/d0abac95583b52a3b35f74a215567334_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..7f9b7bcc60b9863d05c3b630fa1539901bab5399 --- /dev/null +++ b/marked/G/T-REC-G.981-199401-I_PDF-E/d0abac95583b52a3b35f74a215567334_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:3f304cae6f1fa9c74edd7640a0eb8496f6d35700b29796c91b275363bdd8f0ee +size 45071 diff --git a/marked/G/T-REC-G.981-199401-I_PDF-E/fc46871d72c65d3381d9201646d23439_img.jpg b/marked/G/T-REC-G.981-199401-I_PDF-E/fc46871d72c65d3381d9201646d23439_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..808e00e53c8c43df869cb15fd3172ebd77ef67ee --- /dev/null +++ b/marked/G/T-REC-G.981-199401-I_PDF-E/fc46871d72c65d3381d9201646d23439_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:361b60af66beade77e102a50c44a0f0b7b99a3ec99b269a2caf7ceaef22ad406 +size 62279 diff --git a/marked/G/T-REC-G.981-199401-I_PDF-E/raw.md b/marked/G/T-REC-G.981-199401-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..0797e936f2c11dafb376161851fbe8af1fe1028d --- /dev/null +++ b/marked/G/T-REC-G.981-199401-I_PDF-E/raw.md @@ -0,0 +1,386 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.981** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(01/94) + +**DIGITAL SECTIONS AND DIGITAL +LINE SYSTEMS** + +--- + +**PDH OPTICAL LINE SYSTEMS +FOR THE LOCAL NETWORK** + +**ITU-T Recommendation G.981** + +(Previously "CCITT Recommendation") + +--- + +# FOREWORD + +The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). + +ITU-T Recommendation G.981 was prepared by ITU-T Study Group 15 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 20th of January 1994. + +--- + +# NOTE + +In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +# CONTENTS + +| | Page | +|------------------------------------------------------------------|-------------| +| 1 General ..... | 1 | +| 1.1 Scope ..... | 1 | +| 1.2 Objectives ..... | 1 | +| 1.3 Definitions ..... | 1 | +| 1.4 Applications and configurations ..... | 1 | +| 2 Functions ..... | 4 | +| 3 Optical transmission ..... | 4 | +| 3.1 Duplex method ..... | 4 | +| 3.2 Transmission medium ..... | 4 | +| 3.3 Definition of margins ..... | 5 | +| 3.4 Transmitter ..... | 5 | +| 3.5 Receiver ..... | 6 | +| 3.6 Optical characteristics of one-fibre line terminations ..... | 6 | +| 3.7 Optical path ..... | 6 | +| 4 System performance ..... | 7 | +| 4.1 Error performance ..... | 7 | +| 4.2 Jitter ..... | 7 | +| 5 Operation and maintenance ..... | 7 | +| 6 Power feeding ..... | 8 | +| 7 Environmental conditions ..... | 8 | +| 8 Safety considerations ..... | 8 | + + + +# **PDH OPTICAL LINE SYSTEMS FOR THE LOCAL NETWORK** + +*(Geneva, 1994)* + +# **1 General** + +## **1.1 Scope** + +This Recommendation covers digital line systems for the transmission of signals based on the plesiochronous hierarchy on optical fibre cables in the local network and includes systems conveying the following bit rates: + +- 1544 kbit/s; +- 2048 kbit/s; +- 34 368 kbit/s. + +This Recommendation is applicable together with the relevant Recommendations on digital sections for the respective applications. Those include: + +- G.962 for ISDN primary rate access at 2048 kbit/s; +- G.963 for ISDN primary rate access at 1544 kbit/s. + +## **1.2 Objectives** + +The aim of this Recommendation is to achieve longitudinal compatibility of different digital line systems on elementary cable sections, i.e. the possibility of installing digital line systems, produced by different manufacturers, on the same optical fibre cable. + +The systems should: + +- be in line with the error performance specified in Recommendations G.821 (local grade) and G.826 and should harmonize with the relevant Recommendations; +- be able to provide access to the majority of customers without the use of regenerators; +- be able to support the relevant maintenance functions; +- comply with various national regulations concerning EMI. + +NOTE – The possibility of transverse compatibility is for further study. + +## **1.3 Definitions** + +For the purpose of this Recommendation, the digital optical line systems can be represented as in Figure 1. The systems have no intermediate regenerators. + +## **1.4 Applications and configurations** + +The transmission system may be applied for ISDN-primary rate access, leased lines or access to other network capabilities using the bit rates defined in 1.1. + +Possible configurations in the access network are shown in Figure 2. + +![Diagram showing two fibre system (a) and one fibre system (b) configurations. (a) shows separate transmit (Tx) and receive (Rx) paths between an NT1 and an LT. (b) shows a single fibre path with bidirectional traffic between an NT1 and an LT. Reference points T, V, C, S, and R are indicated.](547f726730e589392f239257a833ede3_img.jpg) + +**a) Two-fibre system** + +T1512170-92/d01 + +**b) One-fibre system** + +Diagram showing two fibre system (a) and one fibre system (b) configurations. (a) shows separate transmit (Tx) and receive (Rx) paths between an NT1 and an LT. (b) shows a single fibre path with bidirectional traffic between an NT1 and an LT. Reference points T, V, C, S, and R are indicated. + +NT1 Line termination function, customer side (network termination) for ISDN applications: network termination 1 as defined in Recommendation I.411 + +LT Line termination function, network side for ISDN applications: line termination as defined in Recommendation I.112 + +C Optical connector at the equipment + +T Equipment interface according to Recommendation G.703, customer side for ISDN applications: user network interface as defined in Recommendation I.431 + +V Equipment interface according to Recommendation G.703, network side for ISDN applications: digital exchange interface as defined in Recommendation Q.512 + +S Point on the optical fibre just after the transmitter (TX) optical connector (C) + +R Point on the optical fibre just before the receiver (RX) optical connector (C) + +#### NOTES + +1 Additional connectors at a distribution frame (if used) are considered to be part of fibre link and to be located between points S and R. + +2 The coupling function of one-fibre systems which combines the two directions on one fibre, is considered part of the line terminal and not of the optical path. + +3 The abbreviations NT1 and LT have been defined elsewhere for ISDN reference configurations. In this Recommendation they are used more generically, i.e. in all applications. + +FIGURE 1/G.981 +**Reference points for system specification** + +![Diagram showing two configurations of a digital system: Direct access and Remote access. Both show the flow from Customer equipment through NT1 and LT components to an ISDN-Switch (ET) or transmission score network. The Direct access path includes an 'Access digital section' between NT1 and LT, and a 'Bit-transparent digital path' ending at the ISDN-Switch. The Remote access path includes multiple 'Access digital sections' and a central switching area with LT', MUX, and multiple applications (Note 1, Note 2). The ISDN-Switch is labeled with '(Note 3) V''.](fc46871d72c65d3381d9201646d23439_img.jpg) + +Customer equipment + +Direct access + +NT1 + +LT + +Access digital section + +Remote access + +NT1 + +LT + +Access digital section + +V + +(Note 1) + +LT' + +LT + +(Note 2) + +MUX + +(Note 3) V' + +ISDN-Switch (ET) or transmission score network or other network node + +Bit-transparent digital path + +T1512180-92/d02 + +Diagram showing two configurations of a digital system: Direct access and Remote access. Both show the flow from Customer equipment through NT1 and LT components to an ISDN-Switch (ET) or transmission score network. The Direct access path includes an 'Access digital section' between NT1 and LT, and a 'Bit-transparent digital path' ending at the ISDN-Switch. The Remote access path includes multiple 'Access digital sections' and a central switching area with LT', MUX, and multiple applications (Note 1, Note 2). The ISDN-Switch is labeled with '(Note 3) V''. + +#### NOTES + +- 1 This application requires line systems LT' of the same bit rate as the NT1/LT line system. The LT' are outside the scope of this Recommendation. +- 2 Multiple applications of digital sections and multiplexers are possible. +- 3 In the case of "remote access" in ISDN the digital access link is terminated at the ET by a V3' interface, which is electrically identical with the V3 reference point as in the case of the direct access. + +FIGURE 2/G.981 +Examples of configurations of the digital system + +## 2 Functions + +The functions are detailed in the relevant Recommendations on digital sections. + +Figure 3 gives an overview of the generic functions of the systems. + +![Diagram showing the generic functions of NT1 and LT systems. The diagram consists of two main blocks, NT1 and LT, connected by horizontal lines representing data flow. NT1 has six stacked boxes: Information channels (Note 1), Bit timing, Other timing (Note 2), Frame alignment (Note 3), Power feeding, and Operations and maintenance. LT has five corresponding stacked boxes. Arrows indicate bidirectional flow for most functions, except for Power feeding which is unidirectional from LT to NT1.](d0abac95583b52a3b35f74a215567334_img.jpg) + +The diagram illustrates the generic functions of NT1 and LT systems. It shows two main blocks, NT1 and LT, connected by horizontal lines representing data flow. NT1 has six stacked boxes: Information channels (Note 1), Bit timing, Other timing (Note 2), Frame alignment (Note 3), Power feeding, and Operations and maintenance. LT has five corresponding stacked boxes. Arrows indicate bidirectional flow for most functions, except for Power feeding which is unidirectional from LT to NT1. + +T1512190-92/d03 + +Diagram showing the generic functions of NT1 and LT systems. The diagram consists of two main blocks, NT1 and LT, connected by horizontal lines representing data flow. NT1 has six stacked boxes: Information channels (Note 1), Bit timing, Other timing (Note 2), Frame alignment (Note 3), Power feeding, and Operations and maintenance. LT has five corresponding stacked boxes. Arrows indicate bidirectional flow for most functions, except for Power feeding which is unidirectional from LT to NT1. + +#### NOTES + +- 1 The type of information channels depends on the application. They are defined in the relevant section Recommendation. +- 2 The processing of other timing (e.g. octet timing) is based on bit timing as far as the functions in NT1 and LT are concerned. +- 3 The necessity and details of this function depend on the application and are specified in the appropriate section Recommendation. + +FIGURE 3/G.981 +Overview of the generic functions of the systems + +## 3 Optical transmission + +## 3.1 Duplex method + +The system may use one of the following duplex methods: + +- 1) the use of two fibres, one fibre for each direction; +- 2) the use of one fibre for both directions, applying: + - a) time division to separate the directions (TDM); or + - b) wavelength division to separate the directions (WDM); or + - c) subcarrier division to separate the directions (SCDM). + +## 3.2 Transmission medium + +Single mode optical fibres conforming to Recommendation G.652 should be used. + +NOTE – Some Administrations may use already installed multimode fibres conforming to Recommendation G.651. Performance of such systems is beyond the scope of this Recommendation. + +## 3.3 Definition of margins + +For the purposes of this Recommendation, the total system margin is subdivided into two main contributions. The allocation of these margins is shown in Figure 4. + +![Diagram illustrating the allocation of margins in an optical system. The system consists of a Transmitter (Tx) connected to a cable, which is connected to a receiver (Rx). The cable margin (Mc) is defined between points S and R. The equipment margin (Me) is defined between points R and C. The diagram shows the flow from Tx to Rx, with the cable margin (Mc) and equipment margin (Me) indicated.](562f471e8153729557e6a4ee6343c32c_img.jpg) + +The diagram shows a block diagram of an optical communication system. It starts with a transmitter (Tx) on the left, followed by a cable. The cable has two interfaces: S (Source) at the Tx end and R (Receiver) at the Rx end. The cable margin (Mc) is indicated between S and R. The equipment margin (Me) is indicated between R and the receiver (Rx) on the right. There are also labels C (Connector) at both the Tx and Rx ends. A reference code T1512200-92/d04 is shown below the Rx block. + +Diagram illustrating the allocation of margins in an optical system. The system consists of a Transmitter (Tx) connected to a cable, which is connected to a receiver (Rx). The cable margin (Mc) is defined between points S and R. The equipment margin (Me) is defined between points R and C. The diagram shows the flow from Tx to Rx, with the cable margin (Mc) and equipment margin (Me) indicated. + +FIGURE 4/G.981 +Allocation of margins + +### 3.3.1 Cable margin (Mc) + +The cable margin (Mc) covers allowances for: + +- i) future modifications to the cable configuration (additional splices, increased cable lengths, etc.); +- ii) fibre cable performance variations due to environmental factors; +- iii) degradation of any connector and optical passive devices between points S and R when provided. + +### 3.3.2 Equipment margin (Me) + +The equipment margin (Me) covers allowances for the effect of time and environmental factors on equipment performance (e.g. launched power, receiver sensitivity, equipment connector degradations). + +#### NOTES + +1 The design margin, which covers the allowance for the tolerances on the characteristics of the various components of the system, is not considered because worst-case values for such characteristics are reflected in the specifications of clause 4. + +2 The system margin is in relation to a BER threshold of $1 \times 10^{-10}$ even though for practical reasons the measurements of receiver sensitivity may be carried out at other thresholds. + +3 The worst-case approach adopted in this Recommendation leaves some additional margin in operating systems which can be considered as an unallocated margin. + +## 3.4 Transmitter + +### 3.4.1 Optical source type + +The systems may employ either MLM-lasers (multi-longitudinal mode lasers) or LEDs (light-emitting diodes) as sources. Lasers should not require cooling. + +### 3.4.2 Spectral characteristics + +The spectrum and wavelength ranges of the optical source are determined by the characteristics of the optical path and the minimum performance required. + +NOTE – For single-mode systems the lower wavelength limit is determined from consideration of cut-off wavelength and possibly dispersion effects, while the upper wavelength limit is due to consideration of attenuation, in particular OH peak related excess losses, and possibly dispersion. The possibility of specifying spectral characteristics of the line interface is for further study. + +## 3.5 Receiver + +The optical receiver dynamic range should be sufficient to automatically compensate for equipment production tolerances and the effects of temperatures and ageing, as well as for the total range of optical path attenuation. + +The maximum optical path penalty should be $\leq 1$ dB. The optical path penalty takes into account the transmitter spectral characteristics and the fibre dispersion. + +## 3.6 Optical characteristics of one-fibre line terminations + +For one-fibre systems the optical reflectance of the line termination as seen from reference point S/R should be less than $-20$ dB. + +## 3.7 Optical path + +The optical path specifications serve two purposes: + +- to indicate to the network planner the worst-case characteristics the optical path may exhibit to assure satisfactory operation with any equipment; +- to indicate to the equipment designer the worst-case path characteristics the equipment must be able to accommodate. + +The overall characteristics of the optical path between reference points S and R are determined by: + +- the characteristics of: + - the cabled optical fibres; + - splices; + - connectors; + - other passive optical devices (if any); +- the cable margin. + +Optical fibre cable specifications are given in Recommendation G.652. + +Overall optical path specifications between reference points S and R are given in Table 1 together with the following subclauses. + +TABLE 1/G.981 + +### Optical path specifications + +| Nominal bit rate | | Allowance between S and R at $1 \times 10^{-10}$ BER | | | | +|----------------------------|------------|------------------------------------------------------|-----------------------------------------|---------------------------------------|---------------------------------------------| +| | | Maximum attenuation at 1310 nm (dB) | Maximum dispersion relevant length (km) | Minimum optical return loss at S (dB) | Maximum propagation delay ( $\mu\text{s}$ ) | +| 1544 kbit/s or 2048 kbit/s | Two fibres | 24 | n.a. | n.a. | n.a. | +| | One fibre | 12 | n.a. | 20 | 85 | +| 34 368 kbit/s | Two fibres | 12 | 17 | n.a. | n.a. | +| | One fibre | 12 | 17 | 20 | 85 | +| n.a. Not applicable | | | | | | + +### 3.7.1 Attenuation + +Attenuation specifications are given in terms of worst-case values, including losses to splices, connectors, any passive optical devices (if used) and the cable margin. The values are given for the reference wavelength of 1310 nm (value for further study). The values of fibre attenuation at other wavelengths may be calculated with the procedure specified in Appendix I/G.652. + +### 3.7.2 Dispersion + +The maximum dispersion is determined by the worst-case chromatic dispersion coefficient and the maximum dispersion relevant length. + +The worst-case chromatic dispersion coefficient is specified in Recommendation G.652. Table 1 therefore only specifies the maximum dispersion relevant length. + +NOTE – The length specification in Table 1 refers to chromatic dispersion only. The network operator may choose to deploy fibres with better than worst-case chromatic dispersion, thus allowing longer spans in terms of real length, if the original system were dispersion limited. + +### 3.7.3 Optical return loss + +At the considered bit rates and using LED or MLM lasers this parameter is not expected to be relevant for systems employing one fibre per direction. However it may be relevant for systems employing one fibre for both directions with time or subcarrier division to separate directions. + +The optical return loss includes reflections in the optical path between S and R but not at the receiving connector and at the electro-optical receiving device. + +## 4 System performance + +## 4.1 Error performance + +The digital line systems described in this Recommendation are required to provide error performance in accordance with the relevant section Recommendations under all specified working conditions. + +The transmitter and receiver should be designed so that a $BER \leq 1 \times 10^{-10}$ is obtained when operating over an optical path between points S and R as specified in 3.7 with no external electromagnetic or electrostatic interference. + +## 4.2 Jitter + +Jitter is specified in the relevant Recommendations on digital sections. + +## 5 Operation and maintenance + +The required minimum operation and maintenance functions are specified in the relevant Recommendations on digital sections. + +System specific operation and maintenance functions are for further study. + +The necessity and specification of an F interface at the LT (for local supervision, workstation) and/or a Q-interface at the LT (for connection to the Telecommunications Management Network according to Recommendation G.771) is for further study. + +## **6 Power feeding** + +Both NT1 and LT are fed locally. The details of power feeding should comply with national standards. + +Power feeding of NT1 in the application of ISDN primary rate access is defined in Recommendation I.431. Other power requirements are for further study. + +## **7 Environmental conditions** + +Climatic conditions and electromagnetic compatibility requirements are under study in IEC. Appropriate references include IEC 721-3-1 for climatic conditions and IEC 801-2 and 801-3 for electromagnetic compatibility. Equipment shall meet all specifications when normal operating conditions are fulfilled. + +## **8 Safety considerations** + +The Recommendations for guidance for the safe use, maintenance and service of line systems on optical fibre cables with operating wavelengths between 400 nm and 3000 nm are to be found in IEC 825-1 and IEC 825-2. \ No newline at end of file diff --git a/marked/G/T-REC-G.983.2-200507-I_PDF-E/00a8a26e216a931d627c3524c0ccb6cd_img.jpg b/marked/G/T-REC-G.983.2-200507-I_PDF-E/00a8a26e216a931d627c3524c0ccb6cd_img.jpg new file mode 100644 index 0000000000000000000000000000000000000000..11be3fe246b1a934feecb8a2126b508078fb0a87 --- /dev/null +++ b/marked/G/T-REC-G.983.2-200507-I_PDF-E/00a8a26e216a931d627c3524c0ccb6cd_img.jpg @@ -0,0 +1,3 @@ +version https://git-lfs.github.com/spec/v1 +oid sha256:2ae33cda7536e6054dd58c648f1433d449658b5aa8b1af569de25095df34d771 +size 38880 diff --git a/marked/G/T-REC-G.983.2-200507-I_PDF-E/02420fc52f01ed8c3d754ce46e269309_img.jpg 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sha256:c446c4b6876986b36025491f3722050c3d931cea7079420ba123be7a178bd757 +size 41369 diff --git a/marked/G/T-REC-G.983.4-200111-I_PDF-E/raw.md b/marked/G/T-REC-G.983.4-200111-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..7e4426f86a0e5c439a5440d4643732ac0ed6ecac --- /dev/null +++ b/marked/G/T-REC-G.983.4-200111-I_PDF-E/raw.md @@ -0,0 +1,3003 @@ + + +![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with intersecting lines. + +ITU logo + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.983.4** + +(11/2001) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical line +systems for local and access networks + +--- + +**A broadband optical access system with +increased service capability using dynamic +bandwidth assignment** + +ITU-T Recommendation G.983.4 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# **A broadband optical access system with increased service capability using dynamic bandwidth assignment** + +## **Summary** + +This Recommendation specifies requirements for adding Dynamic Bandwidth Assignment (DBA) functionality to the Broadband Optical Access Systems defined in ITU-T Rec. G.983.1. The use of DBA functionality enables dynamic sharing of upstream bandwidth. This dynamic sharing uses upstream bandwidth more efficiently and enables additional services flexibility. This Recommendation captures specifications for DBA operation and for DBA-related communication between the OLT and the ONUs/ONTs. + +###### **Source** + +ITU-T Recommendation G.983.4 was prepared by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 29 November 2001. + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2002 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. + +# CONTENTS + +###### Page + +| | | | +|-------|-----------------------------------------------------------------|----| +| 1 | Introduction ..... | 1 | +| 1.1 | Scope ..... | 1 | +| 1.2 | Background..... | 1 | +| 1.2.1 | Bandwidth assignment in non-DBA G.983.1 systems..... | 1 | +| 1.2.2 | Enhancing the bandwidth assignment on G.983.1 PON systems ..... | 2 | +| 1.2.3 | Effectiveness of dynamic bandwidth assignment ..... | 2 | +| 1.2.4 | General DBA approaches..... | 3 | +| 1.2.5 | Features and Migration scenarios for DBA..... | 4 | +| 1.2.6 | Requirements for this Recommendation ..... | 4 | +| 1.2.7 | Layered architecture ..... | 4 | +| 1.3 | Architectural Drawing ..... | 5 | +| 1.4 | T-CONT priority hierarchy ..... | 6 | +| 1.5 | Objectives..... | 7 | +| 2 | References ..... | 7 | +| 3 | Abbreviations ..... | 8 | +| 4 | Definitions ..... | 10 | +| 5 | Architecture of the optical access network..... | 12 | +| 5.1 | Network architecture ..... | 12 | +| 5.1.1 | FTTCab/C/B scenario ..... | 13 | +| 5.1.2 | FTTH scenario..... | 13 | +| 5.1.3 | DBA installations Scenario for FTTx ..... | 14 | +| 5.2 | Reference configuration ..... | 14 | +| 5.2.1 | Service node interface ..... | 15 | +| 5.2.2 | Interface at the reference points S/R and R/S..... | 15 | +| 5.3 | Functional blocks..... | 15 | +| 5.3.1 | Optical line termination..... | 15 | +| 5.3.2 | Optical network unit/optical network termination ..... | 16 | +| 5.3.3 | Optical distribution network..... | 16 | +| 5.4 | ONU/ONT functional block ..... | 17 | +| 5.4.1 | NSR-ONU/ONT functional block..... | 17 | +| 5.4.2 | SR-ONU/ONT functional block..... | 18 | +| 5.5 | Optical Line Termination functional block ..... | 19 | +| 5.5.1 | Non-DBA-OLT functional block..... | 19 | +| 5.5.2 | DBA-OLT functional block ..... | 20 | +| 5.6 | Optical distribution network functional block..... | 21 | +| 5.6.1 | Passive optical elements..... | 21 | + +| | Page | +|-------------------------------------------------------------------------|-------------| +| 5.6.2 Optical interfaces..... | 22 | +| 6 Services..... | 23 | +| 7 User network interface and service node Interface ..... | 24 | +| 8 Optical network requirements ..... | 24 | +| 8.1 Layered structure of the optical network..... | 24 | +| 8.2 Physical medium dependent layer requirements for the ATM-PON ..... | 25 | +| 8.3 Transmission convergence layer requirements for the ATM-PON..... | 25 | +| 8.3.1 Point-to-multipoint capacities for downstream and upstream..... | 25 | +| 8.3.2 Maximum payload capacities for downstream and upstream ..... | 25 | +| 8.3.3 Downstream interface ..... | 25 | +| 8.3.4 Upstream interface ..... | 25 | +| 8.3.5 Transport specific TC interface..... | 25 | +| 8.3.6 ATM specific TC functions..... | 47 | +| 8.3.7 OAM functions..... | 47 | +| 8.3.8 Messages in the PLOAM channel..... | 52 | +| 8.3.9 Automatic protection switching ..... | 59 | +| 8.4 Ranging method..... | 59 | +| 8.4.1 Scope of the applied ranging method ..... | 59 | +| 8.4.2 Features of ranging method for DBA..... | 59 | +| 8.4.3 Phase relation specification between downstream and upstream..... | 59 | +| 8.4.4 Definition of messages used in the ranging protocol ..... | 59 | +| 8.4.5 Ranging procedure ..... | 59 | +| 8.4.6 Ranging time requirements ..... | 64 | +| 8.5 Handshake procedures..... | 64 | +| 8.5.1 Overall handshake procedure ..... | 64 | +| 8.5.2 Negotiated parameters ..... | 64 | +| 8.5.3 Detailed procedures..... | 65 | +| 8.6 Operations for creation and deletion of T-CONTs..... | 68 | +| 8.6.1 Requirements for operations of T-CONT status change ..... | 68 | +| 8.6.2 Operations for creation of T-CONTs ..... | 68 | +| 8.6.3 Operations for deletion of T-CONTs ..... | 72 | +| 8.6.4 Impact by T-CONT status change..... | 74 | +| 9 Operations Administration and Maintenance (OAM) functionality ..... | 75 | +| 10 Performance..... | 75 | +| 11 Environmental condition ..... | 75 | +| 12 Safety ..... | 75 | + +| | Page | +|-----------------------------------------------------------------------------|-------------| +| Appendix I – Algorithm for DBA..... | 76 | +| I.1   Algorithms for detecting ONU/ONT status for SR-ONU/ONT..... | 76 | +| I.2   Algorithms for monitoring cell streams at OLT from NSR-ONUs/ONTs..... | 76 | +| I.3   Algorithms to update bandwidth ..... | 76 | +| I.5   Algorithms for grant assignment..... | 79 | +| I.6   Control allowing for Upstream Congestion of the OLT NNI ..... | 79 | +| Appendix II – Options for minislot format and negotiating procedures ..... | 80 | +| II.1   Extended T-CONT reporting options ..... | 80 | +| II.1.1   Report type field..... | 80 | +| II.1.2   Reporting capability ..... | 80 | +| II.1.3   Usage of extended reporting types ..... | 81 | + + + +# **A broadband optical access system with increased service capability using dynamic bandwidth assignment** + +# **1 Introduction** + +## **1.1 Scope** + +This Recommendation describes enhanced capabilities for flexible optical access networks based on ITU-T Rec. G.983.1. Specifically, this Recommendation describes the functions that extend ITU-T Rec. G.983.1 to enable Dynamic Bandwidth Assignment (DBA). + +The requirements and specifications preserve backward compatibility and interoperability with the current G.983.1 systems, including management systems. + +This Recommendation includes: + +- Performances objectives (for example bandwidth assignment delay, maximum waiting time). +- Application functionality (for example dynamic bandwidth assignment for bursty traffic and for ONU/ONT aggregated traffic composed of different traffic classes). +- Fairness criteria and protocols (for example dynamic bandwidth assignment based on ONU/ONT status reporting, dynamic bandwidth assignment based on OLT monitoring, dynamic bandwidth assignment based on a combination of reporting and monitoring). +- Backwards compatibility and interoperability that allows legacy OLTs and ONUs/ONTs to operate in systems where DBA is employed. + +It is anticipated that the introduction of DBA functionality into B-PON systems will increase efficiency and therefore lower the cost of providing broadband services. + +## **1.2 Background** + +### **1.2.1 Bandwidth assignment in non-DBA G.983.1 systems** + +The current method for bandwidth assignment via grant control on ITU-T G.983.1 systems is described below. + +ITU-T Rec. G.983.1 specifies a flexible access platform to provide broadband services through passive optical networks. It defines physical and link layer requirements. Traffic is conveyed in the passive optical network in the following frame formats. + +The upstream traffic from the ONUs/ONTs to the OLT is transferred in a frame of 53 timeslots (cells/slots). Each timeslot consists of three bytes of PON layer overhead and an ATM cell or a PLOAM cell. The upstream bandwidth is shared among the associated ONUs/ONTs. The OLT controls each upstream transmission from the ONUs/ONTs on a timeslot-by-timeslot basis. This is accomplished by sending data grants in downstream PLOAM cells. + +PLOAM data grant cells are sent in the downstream direction to all ONUs/ONTs. The data grants are addressed to specific ONUs/ONTs and contain parameters that include the number of upstream data grants and the timeslots for the grants that are assigned to the individual ONU/ONT. Currently the grants are assigned in a static manner. + +### 1.2.2 Enhancing the bandwidth assignment on G.983.1 PON systems + +In ITU-T Rec. G.983.1, the OLT grant generation and distribution are updated when a new connection is provisioned on a PON or an existing connection is removed from a PON. However, there are also other occasions when bandwidth is reassigned. Once the bandwidth is provisioned, the OLT will continuously send the assigned grants to the associated ONUs/ONTs; subsequently, the OLT will receive corresponding user cells in the upstream. This current granting mechanism is most efficient for real time traffic. For example, real time traffic (represented by circuit emulation services) is a typical application that is provided over an ATM DBR Class 1 service connection. This service will generate a well-behaved traffic pattern and can be readily accommodated using the static bandwidth assignment method. + +However, ITU-T Rec. G.983.1 is intended to enable a wide range of broadband services, including those that do not have a constant bit rate. For example, the Internet connects to many bursty traffic sources, which are best accommodated by ATM SBR Class 2 or GFR, which have less rigid requirements on cell transfer delay and cell delay variation. Mapping these non-real-time services into a fixed bandwidth channel prevents the ONUs/ONTs on a PON from dynamically sharing the upstream PON bandwidth. For these non-real-time traffic types, the ability to assign bandwidth dynamically is expected to provide higher efficiency than the current static granting mechanisms. + +### 1.2.3 Effectiveness of dynamic bandwidth assignment + +A Dynamic Bandwidth Assignment (DBA) mechanism improves the efficiency of the PON upstream bandwidth by dynamically adjusting the bandwidth among the ONUs/ONTs in response to ONU/ONT bursty traffic requirements. The practical benefits of DBA are twofold. First, the network operators can add more subscribers to the PON due to more efficient bandwidth use. Second, the subscribers can enjoy enhanced services, such as those requiring bandwidth peaks that would extend beyond the traditional fixed allocation. A comparison between the current static mechanism and DBA is shown in Figure 1. Three ONUs/ONTs are represented and labelled No. 1, No. 2 and No. 3. ONU/ONT No. 1 requires constant bit rate traffic such as DBR Class 1, which is carried efficiently using the static bandwidth assignment method. ONU/ONT No. 2 and ONU/ONT No. 3, however, both have bursts of traffic; traffic from ONU/ONT No. 3 also has delay requirements. With static bandwidth allocation (shown in Figure 1 a)), traffic from ONU/ONT No. 2 would be lost and traffic from ONU/ONT No. 3 would be delayed. The efficiency of DBA is shown in Figure 1 b)), where ONU/ONT No. 3 is dynamically assigned enough bandwidth to carry its traffic burst, followed by ONU/ONT No. 2 being dynamically assigned sufficient bandwidth for its traffic. + +![Figure 1/G.983.4 – Comparison between the current mechanism and DBA. The diagram is divided into two parts: (a) Transfer by Static bandwidth assignment and (b) Transfer by DBA. Part (a) shows three ONUs/ONTs (1, 2, and 3) with different traffic types: ONT #1 has constant bit rate traffic, ONT #2 has bursty traffic, and ONT #3 has bursty and delay sensitive traffic. Under static assignment, ONT #2 loses traffic and ONT #3 experiences delayed traffic. Part (b) shows the same ONUs/ONTs under DBA, where bandwidth is dynamically assigned, allowing all traffic to be transferred without loss or delay.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Constant bit rate traffic + +Original traffic + +ONU/ONT #1 + +ONU/ONT #2 + +Bursty traffic + +Bursty and delay sensitive traffic + +ONU/ONT #3 + +Lost traffic in #2 + +Delayed traffic in #3 + +ONU/ONT #1 + +ONU/ONT #2 + +ONU/ONT #3 + +a) Transfer by Static bandwidth assignment + +ONU/ONT #1 + +ONU/ONT #2 + +ONU/ONT #3 + +b) Transfer by DBA + +T1546240-02 + +Figure 1/G.983.4 – Comparison between the current mechanism and DBA. The diagram is divided into two parts: (a) Transfer by Static bandwidth assignment and (b) Transfer by DBA. Part (a) shows three ONUs/ONTs (1, 2, and 3) with different traffic types: ONT #1 has constant bit rate traffic, ONT #2 has bursty traffic, and ONT #3 has bursty and delay sensitive traffic. Under static assignment, ONT #2 loses traffic and ONT #3 experiences delayed traffic. Part (b) shows the same ONUs/ONTs under DBA, where bandwidth is dynamically assigned, allowing all traffic to be transferred without loss or delay. + +**Figure 1/G.983.4 – Comparison between the current mechanism and DBA** + +### 1.2.4 General DBA approaches + +Two different DBA mechanisms are summarized below. + +Method one is referred to as "idle cell adjustment". In this approach, the OLT monitors the bandwidth used by each of the ONUs/ONTs. If the utilization exceeds a predefined threshold, then additional bandwidth will be assigned if it is available. In this approach, no bandwidth resources are needed for the ONU/ONT to report status; the OLT infers individual ONU/ONT bandwidth needs from the current utilization. However, a possible drawback of this approach would be slow reaction to ONUs/ONTs requesting upstream bandwidth. + +Method two is called "buffer status reporting". ONUs/ONTs using this approach report the status of their buffers by using mini-slots. The OLT reassigns the bandwidth according to the ONU/ONT reports. + +### 1.2.5 Features and Migration scenarios for DBA + +Other features of DBA include the ability to accommodate several Transmission Containers (T-CONTs) in one ONU/ONT. T-CONTs in an ONU/ONT can operate independently of one another. The DBA mechanism associates grant characteristics to a T-CONT type classification. This classification enables the PON to better handle traffic flows that have similar characteristics. This classification is not intended, in any way or form, to change the related ITU-T Recommendations concerning ATM services. + +The introduction of DBA into a system can be broken down into several steps. In the first step, an OLT with DBA capability is installed into a system that previously had no DBA capability. With no DBA capability, the system ONUs/ONTs do not explicitly report their buffer status and are called Non-Status-Reporting ONUs/ONTs (NSR-ONUs/ONTs). The OLT can use the idle cell adjustment approach for DBA. Next, ONUs/ONTs with buffer status reporting capability – called Status Reporting ONUs/ONTs (SR-ONUs/ONTs) – can be installed and the OLT can use the buffer status reports to allocate bandwidth to the ONUs/ONTs. DBA must also operate in a mixed case of NSR-ONUs/ONTs and SR-ONUs/ONTs. Moreover, if we define multiple T-CONTs in one ONU/ONT, DBA can provide more complicated services. + +### 1.2.6 Requirements for this Recommendation + +This Recommendation is needed to ensure interoperability between OLTs and ONUs/ONTs where one or more OLTs and/or ONUs/ONTs on a PON use DBA functionality. The specifications, including the PON frame formats and existing PLOAM cell format and message types, are consistent with ITU-T Rec. G.983.1 whenever possible. Full compatibility is required between DBA-capable and non-DBA-capable elements. Specifically the following combinations must be supported: + +- NSR-ONUs/ONTs must interoperate with non-DBA-OLTs (a non-DBA system). +- NSR-ONUs/ONTs must interoperate with DBA-OLTs (idle cell monitoring). +- SR-ONUs/ONTs must interoperate with non-DBA OLTs (by disabling ONU/ONT status reporting). +- SR-ONUs/ONTs must interoperate with DBA-OLTs (status reporting DBA or idle cell monitoring). + +In addition, both non-DBA-OLTs and DBA-OLTs must be able to support a mixture of NSR-ONUs/ONTs and SR-ONUs/ONTs on the same PON. The detailed operations in these combinations are described in 8.3.5.10.5. + +The following items are included in this Recommendation: + +The method for reporting ONU/ONT status is defined for SR-ONUs/ONTs. + +The definition of T-CONT types, including support for variable rate services. + +Performance benchmarks are addressed for: + +- ONU/ONT bandwidth request detection. +- ONU/ONT bandwidth request reporting. +- OLT grant recalculation and distribution. + +The number of types and definitions of T-CONTs are described. + +### 1.2.7 Layered architecture + +As previewed in ITU-T Rec. G.983.1, DBA is a Transmission Convergence layer function, not an ATM layer function. Figure 2 shows an example of the layered architecture. + +![Figure 2/G.983.4 – The layer architecture in PON. This diagram illustrates the layered structure of a Passive Optical Network (PON). At the top, three main components are shown in boxes: ONU/ONT, ODN, and OLT. Below the ONU/ONT and OLT boxes, there are two sets of stacked rectangular blocks representing data units. The top set is labeled 'VP' (Virtual Path) and the bottom set is labeled 'VC' (Virtual Circuit). Arrows point from these labels to the corresponding layers in the ONU/ONT and OLT. Below the ONU/ONT, there is a label 'Trail (Note) in PON physical layer' with an arrow pointing to the physical connection area. Below the OLT, there is a label 'T-CONT' with an arrow pointing to a specific layer. The diagram uses 3D perspective to show the internal structure of the data units and their relationship to the network components. A small code 'T1546250-02' is visible at the bottom right of the diagram area.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Figure 2/G.983.4 – The layer architecture in PON. This diagram illustrates the layered structure of a Passive Optical Network (PON). At the top, three main components are shown in boxes: ONU/ONT, ODN, and OLT. Below the ONU/ONT and OLT boxes, there are two sets of stacked rectangular blocks representing data units. The top set is labeled 'VP' (Virtual Path) and the bottom set is labeled 'VC' (Virtual Circuit). Arrows point from these labels to the corresponding layers in the ONU/ONT and OLT. Below the ONU/ONT, there is a label 'Trail (Note) in PON physical layer' with an arrow pointing to the physical connection area. Below the OLT, there is a label 'T-CONT' with an arrow pointing to a specific layer. The diagram uses 3D perspective to show the internal structure of the data units and their relationship to the network components. A small code 'T1546250-02' is visible at the bottom right of the diagram area. + +NOTE – Physical layer Trail includes the point to multi-points relationship between OLT and ONUs/ONTs + +**Figure 2/G.983.4 – The layer architecture in PON** + +## 1.3 Architectural Drawing + +A single queue and multiple queues feeding a single T-CONT Buffer are shown in Figures 3 and 4. + +![Figure 3/G.983.4 – Configurations of T-CONT buffers in one ONU/ONT. This diagram shows the internal architecture of an ONU/ONT. On the left, 'Upstream user cells' enter through a 'UNI' (User Network Interface), represented by a line with a perpendicular tick mark. Inside the ONU/ONT box, there are two stacked 'T-CONT buffer' units, each represented by a dashed oval. Arrows show data flow from the UNI into both buffers. From the buffers, arrows lead to a central point where the data is multiplexed. This multiplexed stream then passes through an 'ODN' (Optical Distribution Network), represented by a line with a circle and three outgoing branches, to an 'OLT' (Optical Line Terminal) box. A small code 'T1546260-02' is visible at the bottom right of the diagram area.](410562339ce067fdc6fa41940c118658_img.jpg) + +Figure 3/G.983.4 – Configurations of T-CONT buffers in one ONU/ONT. This diagram shows the internal architecture of an ONU/ONT. On the left, 'Upstream user cells' enter through a 'UNI' (User Network Interface), represented by a line with a perpendicular tick mark. Inside the ONU/ONT box, there are two stacked 'T-CONT buffer' units, each represented by a dashed oval. Arrows show data flow from the UNI into both buffers. From the buffers, arrows lead to a central point where the data is multiplexed. This multiplexed stream then passes through an 'ODN' (Optical Distribution Network), represented by a line with a circle and three outgoing branches, to an 'OLT' (Optical Line Terminal) box. A small code 'T1546260-02' is visible at the bottom right of the diagram area. + +**Figure 3/G.983.4 – Configurations of T-CONT buffers in one ONU/ONT** + +In Figure 3, an ONU/ONT supports one or more T-CONT buffers that are the object of data grants by an OLT regardless of any internal mechanism as shown in Figure 4. + +![Diagram of internal mechanisms in a T-CONT buffer. It shows an ONU/ONT connected to a UNI (Upstream user cells) and an ODN (Optical Distribution Network) which leads to an OLT. Inside the ONU/ONT, there are multiple T-CONT buffers. One T-CONT buffer is shown with a dashed outline, containing a 'Class buffer' and a 'Priority control' mechanism. Arrows indicate data flow from the UNI through the T-CONT buffers, then through the ODN to the OLT. The diagram is labeled T1546270-02.](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg) + +Diagram of internal mechanisms in a T-CONT buffer. It shows an ONU/ONT connected to a UNI (Upstream user cells) and an ODN (Optical Distribution Network) which leads to an OLT. Inside the ONU/ONT, there are multiple T-CONT buffers. One T-CONT buffer is shown with a dashed outline, containing a 'Class buffer' and a 'Priority control' mechanism. Arrows indicate data flow from the UNI through the T-CONT buffers, then through the ODN to the OLT. The diagram is labeled T1546270-02. + +**Figure 4/G.983.4 – An example of internal mechanisms in a T-CONT buffer** + +In Figure 4, some T-CONT buffers are serviced by an internal scheduler or some other mechanism in an upper layer (for example, the ATM layer). This figure shows one T-CONT buffer with no internal scheduler and one T-CONT buffer that consists of one or more traffic class buffers. In some applications, a priority control mechanism is used. + +## 1.4 T-CONT priority hierarchy + +The priority hierarchy for data grants to T-CONTs is shown in Figure 5. + +![Diagram showing the priority hierarchy for grant allocation. It consists of four stacked boxes representing different bandwidth types. From top to bottom: 'Best effort bandwidth', 'Non-assured bandwidth', 'Assured bandwidth', and 'Fixed bandwidth'. The top box is labeled 'Lowest priority bandwidth' and the bottom box is labeled 'Highest priority bandwidth'. To the right of the boxes, there are double-headed arrows: one spanning the top two boxes labeled 'Additional bandwidth', and another spanning the bottom two boxes labeled 'Guaranteed bandwidth'. The diagram is labeled T1546280-02.](1b5a812c8aa20fd5cba28e97001d32de_img.jpg) + +Diagram showing the priority hierarchy for grant allocation. It consists of four stacked boxes representing different bandwidth types. From top to bottom: 'Best effort bandwidth', 'Non-assured bandwidth', 'Assured bandwidth', and 'Fixed bandwidth'. The top box is labeled 'Lowest priority bandwidth' and the bottom box is labeled 'Highest priority bandwidth'. To the right of the boxes, there are double-headed arrows: one spanning the top two boxes labeled 'Additional bandwidth', and another spanning the bottom two boxes labeled 'Guaranteed bandwidth'. The diagram is labeled T1546280-02. + +**Figure 5/G.983.4 – Priority of bandwidth for grant allocation** + +## 1.5 Objectives + +When providing DBA functionality the following objectives should be observed. + +Compatibility should be maintained with ITU-T Rec. G.983.1 and ITU-T Rec. G.983.2: + +- A single PON will support both SR-ONUs/ONTs and NSR-ONUs/ONTs. + +The cost to implement DBA should remain as low as possible: + +- Cost includes the overall system. +- Strategies that add cost to all ONUs/ONTs (for example requiring excessively large memory buffers at the ONU/ONT) are less desirable. + +Equipment from different vendors should interoperate. + +ATM traffic contracts should be met for each ATM connection in all T-CONTs: + +Grants from the OLT to the T-CONTs on a PON should be equitably distributed. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provision of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.652 (2000), *Characteristics of a single-mode optical fibre cable.* +- [2] ITU-T Recommendation G.671 (2001), *Transmission characteristics of optical components and subsystems.* +- [3] ITU-T Recommendation G.783 (2000), *Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks.* +- [4] ITU-T Recommendation G.902 (1995), *Framework Recommendation on functional access networks (AN) – Architecture and functions, access types, management and service node aspects.* +- [5] ITU-T Recommendation G.957 (1999), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy.* +- [6] ITU-T Recommendation G.958 (1994), *Digital line systems based on the synchronous digital hierarchy for use on optical fibre cables.* +- [7] ITU-T Recommendation G.982 (1996), *Optical access networks to support services up to the ISDN primary rate or equivalent bit rates.* +- [8] ITU-T Recommendation G.983.1 (1998), *Broadband optical access systems based on Passive Optical Networks (PON).* +- [9] ITU-T Recommendation G.983.2 (2000), *ONT management and control interface specification for ATM-PON.* +- [10] ITU-T Recommendation I.321 (1991), *B-ISDN protocol reference model and its application.* +- [11] ITU-T Recommendation I.326 (1995), *Functional architecture of transport networks based on ATM.* +- [12] ITU-T Recommendation I.356 (2000), *B-ISDN ATM layer cell transfer performance.* +- [13] ITU-T Recommendation I.361 (1999), *B-ISDN ATM layer specification.* + +- [14] ITU-T Recommendation I.371 (2000), *Traffic control and congestion control in B-ISDN.* +- [15] ITU-T Recommendation I.371.1 (2000), *Guaranteed frame rate ATM transfer capability.* +- [16] ITU-T Recommendation I.432.1 (1999), *B-ISDN user-network interface – Physical layer specification: General characteristics.* +- [17] ITU-T Recommendation I.610 (1999), *B-ISDN operation and maintenance principles and functions.* +- [18] ITU-T Recommendation I.732 (2000), *Functional characteristics of ATM equipment.* +- [19] ITU-T Recommendation I.751 (1996), *Asynchronous transfer mode management of the network element view.* + +# 3 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|--------|-----------------------------------------------| +| AF | Adaptation Function | +| AN | Access Network | +| APS | Automatic Protection Switching | +| ATC | ATM Transfer Capability | +| ATM | Asynchronous Transfer Mode | +| BER | Bit Error Ratio | +| BIP | Bit Interleaved Parity | +| B-ISDN | Broadband Integrated Services Digital Network | +| B-PON | Broadband Passive Optical Network | +| CID | Consecutive Identical Digit | +| CPE | Cell Phase Error | +| CRC | Cyclic Redundancy Check | +| DBA | Dynamic Bandwidth Assignment | +| DSL | Digital Subscriber Line | +| E/O | Electrical/Optical | +| FTTB/C | Fibre to the Building/Curb | +| FTTCab | Fibre to the Cabinet | +| FTTH | Fibre to the Home | +| HEC | Header Error Control | +| IEC | International Electrotechnical Commission | +| ISDN | Integrated Services Digital Network | +| LAN | Local Area Network | +| LCD | Loss of Cell Delineation | +| LCF | Laser Control Field | +| LSB | Least Significant Bit | +| LT | Line Terminal | + +| | | +|--------|-------------------------------------------| +| MAC | Media Access Control | +| MSB | Most Significant Bit | +| NSR | Non Status Reporting | +| NT | Network Termination | +| OAM | Operations Administration and Maintenance | +| OAN | Optical Access Network | +| ODF | Optical Distribution Frame | +| ODN | Optical Distribution Network | +| OLT | Optical Line Termination | +| ONT | Optical Network Termination | +| ONU | Optical Network Unit | +| OpS | Operations System | +| PLOAM | Physical Layer OAM | +| PON | Passive Optical Network | +| PRBS | Pseudo Random Bit Sequence | +| PST | PON Section Trace | +| PSTN | Public Switched Telephone Network | +| QoS | Quality of Service | +| RAU | Request Access Unit | +| RMS | Root Mean Square | +| SDH | Synchronous Digital Hierarchy | +| SN | Serial Number | +| SNI | Service Node Interface | +| SR | Status Reporting | +| TC | Transmission Convergence | +| T-CONT | Transmission Container | +| TDMA | Time Division Multiple Access | +| UI | Unit Interval | +| UNI | User Network Interface | +| UPC | Usage Parameter Control | +| VC | Virtual Channel | +| VCC | Virtual Channel Connection | +| VCI | Virtual Channel Identifier | +| VoD | Video-on-Demand | +| VP | Virtual Path | +| VPC | Virtual Path Connection | + +| | | +|-----|-------------------------| +| VPG | Virtual Path Group | +| VPI | Virtual Path Identifier | +| WRR | Weighted Round Robin | + +# 4 Definitions + +This Recommendation defines the following terms: + +**4.1 additional bandwidth:** Additional Bandwidth is the summation of Non-assured Bandwidth and Best Effort Bandwidth. + +**4.2 assured bandwidth:** Assured Bandwidth is bandwidth that is always available to the ONU/ONT if the T-CONT buffer is expected to have cells to transmit. If the T-CONT buffer does not have cells to transmit, this bandwidth may be used by other T-CONTs. Assured Bandwidth is therefore able to participate in DBA. + +**4.3 best effort bandwidth:** Best Effort Bandwidth is bandwidth that a T-CONT may be able to use if no higher-priority traffic consumes the bandwidth; there is no assurance or guarantee that the bandwidth will be available. Best Effort Bandwidth is able to participate in DBA. + +**4.4 broadband passive optical network (B-PON):** B-PONs are one-to-many broadband optical transmission systems. B-PONs can transparently transport any type of data, for example voice, video, IP data, etc. The B-PON is able to carry data regardless of the type of data link frame (i.e. not only native ATM but also HDLC Ethernet frame, etc.). + +**4.5 churning:** Churning is a function that can be applied to the downstream user data from an OLT to its ONUs/ONTs. Churning provides the necessary function of data scrambling and offers a low level of protection for data confidentiality. It is installed at the TC layer of the ATM-PON system and can be activated for point-to-point downstream connections. + +**4.6 data grant:** A data grant is sent from an OLT to a T-CONT in an ONU/ONT and indicates permission for the T-CONT to transmit an upstream cell. + +**4.7 dynamic bandwidth assignment (DBA):** is the process by which ONUs/ONTs (and their associated T-CONTs) dynamically request upstream bandwidth (either implicitly or explicitly) and the method, through idle cell monitoring at OLT or buffer status reporting from ONUs/ONTs to OLT, the OLT reassigns upstream bandwidth accordingly. + +**4.8 DBA-OLT:** An OLT that is able to provide DBA functionality on one or more PONs. + +**4.9 diplex working:** Bidirectional communication using a different wavelength for each direction of transmission over a single fibre. + +**4.10 duplex working:** Bidirectional communication using the same wavelength for both directions of transmission over a single fibre. + +**4.11 fixed bandwidth:** Fixed Bandwidth is entirely reserved and cyclically allocated in order to achieve a low cell transfer delay. If a T-CONT is provisioned with Fixed Bandwidth and has no cells to send, grants associated with the Fixed Bandwidth are still sent from the OLT and consequently idle cells will be sent upstream from the ONU/ONT to the OLT. + +**4.12 guaranteed bandwidth:** Guaranteed Bandwidth is the summation of Assured Bandwidth and Fixed Bandwidth. + +**4.13 logical reach:** The logical reach is defined as the maximum length that can be achieved for a particular transmission system independent of optical budget. + +**4.14 maximum bandwidth:** Maximum Bandwidth is the upper limit of bandwidth to be assigned to a T-CONT and is the sum of Guaranteed Bandwidth and the upper limit of Additional Bandwidth. + +**4.15 mean signal transfer delay:** The average upstream and downstream delay values between reference points "V" and "T" in Figure 7; a given value is determined by measuring round-trip delay, then dividing by 2. + +**4.16 non-DBA-OLT:** An OLT that does not provide DBA services but conforms to the existing ITU-T Rec. G.983.1 and G.983.2. + +**4.17 non-assured bandwidth:** Non-assured Bandwidth is a high priority variation of Additional Bandwidth that is assigned to T-CONTs with Assured Bandwidth. Non-assured bandwidth is able to participate in DBA. + +**4.18 Non-Status Reporting ONU/ONT (NSR-ONU/ONT):** ONUs/ONTs that do not communicate their bandwidth needs and requirements to a DBA-OLT. All ONUs/ONTs conforming to ITU-T Recs. G.983.1 and G.983.2 but that do not report buffer status are NSR-ONUs/ONTs. + +**4.19 Optical Access Network (OAN):** The set of access links sharing the same network-side interfaces and supported by optical access transmission systems. The OAN may include a number of ODNs connected to the same OLT. + +**4.20 Optical Distribution Network (ODN):** An ODN provides the optical transport between the OLT and its associated ONUs/ONTs. It uses passive optical components. + +**4.21 Optical Line Termination (OLT):** An OLT provides the network-side interface of the OAN, and is connected to one or more ODNs. + +**4.22 Optical Network Termination (ONT):** An ONT provides the customer-side interface for the OAN, and is connected to one ODN. An ONT is used for FTTH and includes the User Port function. From a DBA point of view, ONT and ONU are identical and are represented by the term "ONU/ONT" in this Recommendation. + +**4.23 Optical Network Unit (ONU):** An ONU provides (directly or remotely) the user-side interface of the OAN, and is connected to the ODN. From a DBA point of view, ONU and ONT are identical and are represented by the term "ONU/ONT" in this Recommendation. + +**4.24 QoS class:** In the context of ATM services, QoS refers to a set of performance parameters that constitute the traffic contract between the subscriber equipment and the network. Examples of these performance parameters include, cell loss ratio, cell transfer delay, and cell delay variation tolerance. The parameters are used to define distinct QoS classes. + +**4.25 ranging:** Ranging is a method of measuring the logical distance between each ONU/ONT and its associated OLT and determining the transmission timing such that upstream cells sent from different ONUs/ONTs on the same ODN do not collide. + +**4.26 service port function:** The Service Port Function (SPF) adapts the requirements defined for a specific SNI to the common bearers handling function and selects the relevant information for treatment in the AN system management function. + +**4.27 Status Reporting ONU/ONT (SR-ONU/ONT):** An ONU/ONT that reports the status of its T-CONT buffers to a DBA-OLT. + +**4.28 surplus bandwidth:** Surplus Bandwidth is PON bandwidth not committed to Fixed Bandwidth or Assured Bandwidth or bandwidth reserved for special usage like OAM. Surplus Bandwidth is able to participate in DBA. + +**4.29 Transmission Containers (T-CONTs):** T-CONTs are used for the management of upstream bandwidth allocation in the PON section of the Transmission Convergence layer. T-CONTs are primarily used to improve the upstream bandwidth use on the PON. + +- T-CONTs carry ATM VPCs and VCCs and report their buffer status to their associated OLTs. +- T-CONTs dynamically receive grants from the OLT. + +- A single T-CONT can carry ATM traffic with various service classes and VCCs and/or VPCs. +- A T-CONT can accommodate one or more physical queues and aggregates them into a single logical buffer. +- A DBA-T-CONT status report summarizes the status of the logical buffer of that T-CONT. +- A T-CONT is a transport entity in the TC layer that transfers higher-layer information transparently from input to output. +- Information traversing a T-CONT is unchanged except where degradation occurs in the transfer process. +- A data grant is associated with one and only one T-CONT. T-CONTs physically occur in the ONU/ONT hardware and software. + +See subclause 8.3.5.10.2 T-CONT types for detailed T-CONT definition and examples. This subclause also details the T-CONT sub-types. + +**4.30 Time Division Multiple Access (TDMA):** Transmission technique that allocates specific timeslot(s) to each traffic source that shares a transmission medium. + +**4.31 user port function:** The User Port Function (UPF) adapts the specific UNI requirements to the core and management functions. The AN may support a number of different accesses and user network interfaces which require specific functions according to the relevant interface specification and the access bearer capability requirements, i.e. bearers for information transfer and protocols. + +**4.32 verification:** It is possible for a malicious user to masquerade as another ONU/ONT and use the network if the user knows that the ONU/ONT is power-off. Verification is a function to check whether the connected ONU/ONT is masquerading. + +# 5 Architecture of the optical access network + +## 5.1 Network architecture + +The optical section of a local access network system could be either point-to-point, point-to-multipoint, active, or passive. Figure 6 shows the architectures considered, which range from Fibre to the Home (FTTH), through Fibre to the Building/Curb (FTTB/C) to Fibre to the Cabinet (FTTCab). The Optical Access Network (OAN) is common to all architectures shown in Figure 6, hence commonality in this system has the potential to generate large worldwide volumes. + +![Diagram of network architecture showing three scenarios: FTTH, FTTB/C, and FTTCab. Each scenario shows a connection from a Home network (UNI) through an Optical Network Unit (ONU) or Network Termination (NT) and then via Fibre or Copper to an Optical Line Termination (OLT) at the SNI. FTTH uses an ONT connected to Fibre. FTTB/C and FTTCab use an NT connected to Copper, which is then connected to an ONU connected to Fibre. The OLT is common to all three scenarios. A legend defines ONU as Optical Network Unit, ONT as Optical Network Termination, OLT as Optical Line Termination, and NT as Network Termination. The diagram is labeled T1528110-98.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +ONU Optical Network Unit + ONT Optical Network Termination + OLT Optical Line Termination + NT Network Termination + +T1528110-98 + +Diagram of network architecture showing three scenarios: FTTH, FTTB/C, and FTTCab. Each scenario shows a connection from a Home network (UNI) through an Optical Network Unit (ONU) or Network Termination (NT) and then via Fibre or Copper to an Optical Line Termination (OLT) at the SNI. FTTH uses an ONT connected to Fibre. FTTB/C and FTTCab use an NT connected to Copper, which is then connected to an ONU connected to Fibre. The OLT is common to all three scenarios. A legend defines ONU as Optical Network Unit, ONT as Optical Network Termination, OLT as Optical Line Termination, and NT as Network Termination. The diagram is labeled T1528110-98. + +**Figure 6/G.983.4 – Network architecture** + +The FTTB/C and FTTCab network options are predominantly different only as a result of implementation, as a result they can be treated the same in this Recommendation. Protocols supported by ONTs on the fibre are the same as those supported by ONUs. In this Recommendation, ONU and ONT are represented as "ONU/ONT". + +### 5.1.1 FTTCab/C/B scenario + +Within this scenario the following service categories have been considered: + +- Asymmetric broadband services (e.g. digital broadcast services, VoD, Internet, distance learning, telemedicine, etc.). +- Symmetric broadband services (e.g. telecommunication services for small business customers, teleconsulting, etc.). +- PSTN and ISDN. The access network must be able to provide, in a flexible way, the narrowband telephone services. + +### 5.1.2 FTTH scenario + +Fibre-to-the-Home service drivers are similar to those of the previous scenarios and include: + +- Consideration of indoor ONUs/ONTs resulting from more favourable environmental conditions. +- No change of an existing ONU/ONT is required when upgrading access network capabilities to accommodate future evolution of broadband and multimedia services. +- Easier maintenance resulting from a passive fibre plant between the OLT and ONUs/ONTs, because fibre systems are regarded as more reliable than hybrid fibre-metallic systems. +- FTTH is a driver for the development of advanced optoelectronics technologies. The higher volumes associated with FTTH should help reduce the costs of optoelectronic components. + +When these factors can be fully used they may counterbalance a slightly higher per line cost when compared to metallic alternatives. In this situation the FTTH scenario may be regarded as economically feasible even in the short term. + +### **5.1.3 DBA installations Scenario for FTTx** + +DBA can be installed for FTTx to increase availability of bandwidth by dynamically allocating all or part of the upstream bandwidth among the ONUs/ONTs. In short, DBA can provide higher performance for services in the FTTx systems specified in 5.1.1 and 5.1.2. DBA should allow the network to accommodate more users than in a non-DBA FTTx system. Bursty data applications should benefit significantly from DBA. + +#### **5.1.3.1 Compatibility between DBA and conventional systems specified in G.983.1** + +Systems and components that are controlled by DBA shall maintain backward compatibility and interoperability with existing systems that conform to ITU-T Rec. G.983.1. In particular, interoperability is required for the following combinations: + +- A DBA-OLT can be replaced by a Non-DBA-OLT that supports NSR-ONUs/ONTs without modification of network design. +- A DBA-OLT shall be able to distinguish between NSR-ONUs/ONTs and SR-ONUs/ONTs without modification to the NSR-ONUs/ONTs. +- A DBA-OLT running in non-DBA mode shall have the same downstream capabilities and provide the same environment as a non-DBA-OLT. Detailed operations of combined configurations for OLTs and ONUs/ONTs are described in 8.3.5.10.5. + +#### **5.1.3.2 Interoperability in multi-vendor environment** + +Multi-vendor interoperability shall be required for all OLTs and ONUs/ONTs. The following requirements should be met: + +- A DBA-OLT shall dynamically and fairly allocate bandwidth on a PON that includes NSR-ONUs/ONTs from different vendors. +- A DBA-OLT shall dynamically and fairly allocate bandwidth on a PON that includes SR-ONUs/ONTs from different vendors as long as these SR-ONUs/ONTs conform to the status reporting technique specified in this Recommendation. +- A DBA-OLT shall dynamically and fairly allocate bandwidth on a PON to any combinations of NSR-ONUs/ONTs and SR-ONUs/ONTs from different vendors. + +## **5.2 Reference configuration** + +The reference configuration is shown in Figure 7. + +The ODN offers one or more optical paths between one OLT and one or more ONUs/ONTs. Each optical path is defined between reference points S and R in a specific wavelength window. The two directions for optical transmission in the ODN are identified as follows: + +- downstream direction is defined as the direction of flow of information from the OLT to the ONU/ONT(s); +- upstream direction is defined as the direction of flow of information from the ONU/ONT(s) to the OLT. + +![Figure 7/G.983.4 – Reference configuration for an ATM based PON. The diagram illustrates the architecture of an ATM-based Passive Optical Network (PON). At the top, a block labeled 'Access Network System Management Functions' is connected via a 'Q3' reference point. Below this, the main signal path flows from left to right. On the left, 'UNI' (User Network Interface) leads to an 'AF' (Adaptation Function) block, which connects to an 'ONU/ONT' (Optical Network Unit/Optical Network Termination) block. Another 'ONU/ONT' is shown above it. These connect via 'R/S' and 'IF_PON' reference points to a central 'ODN' (Optical Distribution Network). The ODN connects via 'S/R' and 'IF_PON' reference points to an 'OLT' (Optical Line Termination) block. The OLT connects via an 'SNI' (Service Node Interface) to a 'Service node function' block. Reference points '(T_B)/(T)' and '(V_B)/(V)' are marked at the UNI and SNI boundaries respectively. A reference point '(a)' is marked between the AF and ONU/ONT blocks.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +- (a) Reference point – This reference point is added to differentiate the AF from the ONU +- AF Adaptation Function +- ODN Optical Distribution Network +- OLT Optical Line Termination +- ONT Optical Network Termination +- ONU Optical Network Unit +- R Point on the optical fibre just before the ONU/ONT[Downstream] or OLT[Upstream] optical point (i.e. optical connector or optical splice) +- S Point on the optical fibre just after the OLT[Downstream] or ONU/ONT[Upstream] optical point (i.e. optical connector or optical splice) + +T1546290-02 + +Figure 7/G.983.4 – Reference configuration for an ATM based PON. The diagram illustrates the architecture of an ATM-based Passive Optical Network (PON). At the top, a block labeled 'Access Network System Management Functions' is connected via a 'Q3' reference point. Below this, the main signal path flows from left to right. On the left, 'UNI' (User Network Interface) leads to an 'AF' (Adaptation Function) block, which connects to an 'ONU/ONT' (Optical Network Unit/Optical Network Termination) block. Another 'ONU/ONT' is shown above it. These connect via 'R/S' and 'IF\_PON' reference points to a central 'ODN' (Optical Distribution Network). The ODN connects via 'S/R' and 'IF\_PON' reference points to an 'OLT' (Optical Line Termination) block. The OLT connects via an 'SNI' (Service Node Interface) to a 'Service node function' block. Reference points '(T\_B)/(T)' and '(V\_B)/(V)' are marked at the UNI and SNI boundaries respectively. A reference point '(a)' is marked between the AF and ONU/ONT blocks. + +**Figure 7/G.983.4 – Reference configuration for an ATM based PON** + +The B-PON system consists of Optical Line Termination (OLT), Optical Network Unit/Optical Network Termination (ONU/ONT), fibre cable, and one or more passive optical splitter(s). Light from the OLT is passively split and distributed to multiple ONUs/ONTs on the ODN. Since each ONU/ONT receives all the information emanating downstream from the OLT, additional capabilities are required to provide privacy and security. In the upstream direction a Time-Division Multiple Access (TDMA) protocol is required. + +### 5.2.1 Service node interface + +See ITU-T Rec. G.902. + +### 5.2.2 Interface at the reference points S/R and R/S + +The interface at reference points S/R and R/S is defined as $IF_{PON}$ . This is a PON-specific interface that supports all the protocol elements necessary to allow the transmission between OLT and ONUs/ONTs. + +## 5.3 Functional blocks + +### 5.3.1 Optical line termination + +The optical line termination (OLT) interfaces to services nodes via the SNI and to the ONUs/ONTs via the ODN. The OLT is responsible for managing all the PON specific aspects of the ATM transport system. An ONU/ONT and its associated OLT provide transparent ATM transport service between the UNIs and the SNI over the PON. Both Non-DBA-OLTs and DBA-OLTs are covered in this Recommendation. + +#### **5.3.1.1 Non-DBA-OLT** + +This type of OLT supports functions specified in ITU-T Rec. G.983.1. + +#### **5.3.1.2 DBA-OLT** + +A DBA-OLT is capable of assigning upstream bandwidth dynamically based on the service contracts of data traffic in the active T-CONTs, the requested bandwidth of the T-CONTs, and the available bandwidth upstream on the PON. In general, operations for DBA can be categorized into three approaches as follows: + +In the first approach, a DBA-OLT updates allocated bandwidth depending on traffic monitoring in the DBA-OLT. + +In the second case, the DBA-OLT updates allocated bandwidth based on reports from SR-ONUs/ONTs. + +The third case, the DBA-OLT updates allocated bandwidth based on the combination of the traffic monitoring in the DBA-OLT and reports from SR-ONUs/ONTs. + +### **5.3.2 Optical network unit/optical network termination** + +The ONU/ONT interfaces over the IFPON to the OLT, and to the UNI. Together with the OLT, the ONU/ONT is responsible for providing transparent ATM transport service between the UNI and the SNI. + +In this architecture, the ATM transport protocols at an IFPON are described as consisting of Physical Media Dependent layer, Transmission Convergence layer, and ATM layer. This architecture is only intended to address the transport of ATM; further detail is contained in ITU-T Rec. I.732. + +The Physical Media Dependent layer includes the modulation schemes for both the upstream and downstream channels (they may be different). It may be possible for the specification to allow for more than one type of Physical Media Dependent layer in a single direction. + +The Transmission Convergence layer will be responsible for managing the distributed access to the upstream PON resource across the multiple ONUs/ONTs. This is a key protocol element and will directly affect the resulting ATM QoS. + +The ATM protocols should see no change in the way they operate over the PON. Within both the OLT and the ONU/ONT functions performed at the ATM layer at both the OLT and ONU/ONT include cell relaying. + +In this Recommendation, ONUs/ONTs are classified into two types: SR-ONU/ONT and NSR-ONU/ONT. These are defined in the following clauses. + +#### **5.3.2.1 NSR-ONU/ONT** + +NSR-ONUs/ONTs do not report T-CONT buffer status explicitly. ONUs/ONTs specified in ITU-T Rec. G.983.1 are NSR-ONUs/ONTs. + +#### **5.3.2.2 SR-ONU/ONT** + +An SR-ONU/ONT reports the status of its T-CONT buffers to the OLT. + +### **5.3.3 Optical distribution network** + +The Optical Distribution Network provides the optical transport between the OLT and its associated ONUs/ONTs. It uses passive optical components. + +## 5.4 ONU/ONT functional block + +As an example, the FTTH ONU/ONT is active and decouples the access network delivery mechanism from the in-house distribution. The ONU/ONT core consists of ODN interface, User Port, Transmission, Services and Customers Multiplexing (MUX)/demultiplexing functions and powering, see Figure 8. + +![Figure 8/G.983.4 – Example of NSR-ONU/ONT functional blocks. The diagram shows a functional block diagram of an NSR-ONU/ONT. It is divided into three main shells: Service shell, Core shell, and Common shell. The Service shell contains two 'User port function' blocks, each with four asterisks below it, representing multiple user ports. The Core shell contains three main blocks: 'Customer and services multiplex/demultiplex function', 'Transmission multiplex/demult. function', and 'ODN interface function'. The Common shell contains 'Power' and 'OAM' blocks. The entire unit is connected to 'Customer' on the left and 'ODN' on the right. A label 'T1546300-02' is at the bottom right.](552265bdbcf6d43d341fd018a9076269_img.jpg) + +The diagram illustrates the functional architecture of an NSR-ONU/ONT. It is structured into three horizontal layers or shells. The top layer, labeled 'Service shell', contains two 'User port function' blocks, each followed by four asterisks (\*), indicating multiple user ports for customer connection. The middle layer, labeled 'Core shell', contains three main functional blocks: 'Customer and services multiplex/demultiplex function', 'Transmission multiplex/demult. function', and 'ODN interface function'. The bottom layer, labeled 'Common shell', contains 'Power' and 'OAM' (Operations, Administration, and Management) blocks. The entire assembly is shown within a large rectangular frame. On the left, two horizontal lines represent the 'Customer' interface. On the right, four horizontal lines represent the 'ODN' (Optical Distribution Network) interface, with four asterisks (\*) between them. A small label 'T1546300-02' is located at the bottom right corner of the diagram. + +Figure 8/G.983.4 – Example of NSR-ONU/ONT functional blocks. The diagram shows a functional block diagram of an NSR-ONU/ONT. It is divided into three main shells: Service shell, Core shell, and Common shell. The Service shell contains two 'User port function' blocks, each with four asterisks below it, representing multiple user ports. The Core shell contains three main blocks: 'Customer and services multiplex/demultiplex function', 'Transmission multiplex/demult. function', and 'ODN interface function'. The Common shell contains 'Power' and 'OAM' blocks. The entire unit is connected to 'Customer' on the left and 'ODN' on the right. A label 'T1546300-02' is at the bottom right. + +Figure 8/G.983.4 – Example of NSR-ONU/ONT functional blocks + +### 5.4.1 NSR-ONU/ONT functional block + +#### 5.4.1.1 Optical Distribution Network interface + +The ODN interface handles the optoelectronic conversion process. The ODN interface extracts ATM cells from the downstream PON payload and inserts ATM cells into the upstream PON payload based on synchronization acquired from the downstream frame timing. Moreover, if multiple T-CONTs exist in one ONU/ONT, these operations are invoked for every T-CONT. + +#### 5.4.1.2 Multiplexing + +The multiplexer (MUX) multiplexes service interfaces to the ODN interface. Only valid ATM cells can be passed through the MUX, so many VPs can share the assigned upstream bandwidth effectively. Moreover, if multiple T-CONTs exist in one ONU/ONT, these operations are invoked for every T-CONT. + +#### 5.4.1.3 User port + +The specific information is described in ITU-T Rec. G.983.1. + +#### 5.4.1.4 ONU/ONT powering + +The specific information is described in ITU-T Rec. G.983.1. + +### 5.4.2 SR-ONU/ONT functional block + +The FTTH ONU/ONT is active and decouples the access network delivery mechanism from the in-house distribution. The ONU/ONT core consists of the ODN interface, User Port, Transmission, Services and Customers Multiplexing (MUX)/demultiplexing functions, status reporting function, detecting function, and powering, see Figure 9. + +![Figure 9/G.983.4 – Example of SR-ONU/ONT functional blocks. The diagram shows a functional block diagram of an SR-ONU/ONT. It is divided into three main sections: Service shell, Core shell, and Common shell. The Service shell contains two 'User port function' blocks, each with three asterisks (*) below it, and a 'Customer and services multiplex/demultiplex function' block. The Core shell contains 'Transmission multiplex/demult. function', 'Status reporting function', and 'Detecting information function' blocks, along with an 'ODN interface function' block. The Common shell contains 'Power' and 'OAM' blocks. The entire unit is connected to 'Customer' on the left and 'ODN' on the right. A label 'T1528130-98' is present at the bottom right.](5a1abd59a95fa47ae192807de151e9eb_img.jpg) + +The diagram illustrates the functional architecture of an SR-ONU/ONT. It is organized into three horizontal layers. The top layer, labeled 'Service shell', contains two 'User port function' blocks on the left, each followed by three asterisks (\*). In the center of this shell is a 'Customer and services multiplex/demultiplex function' block. The middle layer, labeled 'Core shell', contains three stacked blocks: 'Transmission multiplex/demult. function', 'Status reporting function', and 'Detecting information function'. To the right of these is a large 'ODN interface function' block. The bottom layer, labeled 'Common shell', contains 'Power' and 'OAM' blocks. The entire assembly is flanked by 'Customer' on the left and 'ODN' on the right. A small text label 'T1528130-98' is located at the bottom right of the diagram. + +Figure 9/G.983.4 – Example of SR-ONU/ONT functional blocks. The diagram shows a functional block diagram of an SR-ONU/ONT. It is divided into three main sections: Service shell, Core shell, and Common shell. The Service shell contains two 'User port function' blocks, each with three asterisks (\*) below it, and a 'Customer and services multiplex/demultiplex function' block. The Core shell contains 'Transmission multiplex/demult. function', 'Status reporting function', and 'Detecting information function' blocks, along with an 'ODN interface function' block. The Common shell contains 'Power' and 'OAM' blocks. The entire unit is connected to 'Customer' on the left and 'ODN' on the right. A label 'T1528130-98' is present at the bottom right. + +Figure 9/G.983.4 – Example of SR-ONU/ONT functional blocks + +#### 5.4.2.1 Optical Distribution Network interface + +The ODN interface handles the optoelectronic conversion process. The ODN interface extracts ATM cells from the downstream PON payload and inserts ATM cells into the upstream PON payload based on synchronization acquired from the downstream frame timing. Moreover, if multiple T-CONTs exist in one ONU/ONT, these operations are invoked for every T-CONT. + +#### 5.4.2.2 Multiplexing + +The multiplexer (MUX) multiplexes service interfaces to the ODN interface. Only valid ATM cells can be passed through the MUX, so many VPs can share the assigned upstream bandwidth effectively. Moreover, if multiple T-CONTs are contained in one ONU/ONT, these operations are invoked in every T-CONT. + +#### 5.4.2.3 User port + +The specific information is described in ITU-T Rec. G.983.1. + +#### 5.4.2.4 ONU/ONT powering + +The specific information is described in ITU-T Rec. G.983.1. + +#### 5.4.2.5 Reporting function + +A DBA reporting function provides information indicating the bandwidth request status in every T-CONT to the DBA-OLT. Variations of the DBA reporting methods and format are described in 8.3.5.10.1.3. + +#### 5.4.2.6 Detecting function + +The SR-ONU/ONT is capable of performing the status detecting function by monitoring each T-CONT in the SR-ONU/ONT. The queue status of a T-CONT in the ONU/ONT can be detected using this function. + +## 5.5 Optical Line Termination functional block + +### 5.5.1 Non-DBA-OLT functional block + +The OLT is connected to switched networks via standardized interfaces (VB5.x, V5.x, and NNI's). At the distribution side, it presents optical access according to the agreed requirements, in terms of bit rate, power budget, etc. + +The OLT consists of four parts: the service port function; ODN interface; MUX for VP grooming, and static grant assignment (see Figure 10). This combination is not intended to preclude the Virtual Channel (VC) layer function in the OLT. VC layer function is for further study. + +#### 1) *Service port function* + +The function interfaces to service nodes. The service port function may handle inserting ATM cells into the upstream SDH payload and extracting ATM cells from the downstream SDH payload. The function may be duplicated, in which case the protection switching function is necessary. + +#### 2) *MUX* + +The MUX provides VP connections between the service port function and the ODN interface. Different VPs are assigned to different services at IFPON. Various types of information such as bearer content, signalling, and OAM flows are exchanged by using VCs of the VP. + +#### 3) *ODN interface* + +The PON Line Terminal handles the optoelectronic conversion process. The ODN interface handles inserting ATM cells into the downstream PON payload and extracting ATM cells from the upstream PON payload. The difference in functional blocks between Non-DBA-OLT and DBA-OLT is the functionality of Media Access Control (MAC) in ODN interface. For a Non-DBA-OLT, the MAC assigns grants to each T-CONT contained in one ODN according to the T-CONT's contracted service. + +![Functional block diagram of a Non-DBA-OLT showing Core shell, Service shell, ODN interface functions, Transmission MUX/DMUX, ATM cross-connect function, Power, OAM, and Service port functions with their respective network interfaces.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg) + +The diagram illustrates the functional architecture of a Non-DBA-OLT, organized into two main vertical sections: the Core shell and the Service shell. + +- Core shell:** + - Contains two **ODN interface function** blocks, each with a **Static grant assignment** sub-block. These are connected to the left side of the shell. + - A central **Transmission MUX/DMUX** block. + - An **ATM cross-connect function** block. + - At the bottom, there are **Power** and **OAM** blocks. +- Service shell:** + - Contains two **Service port function** blocks, one at the top and one at the bottom. + - The top Service port function is connected to the **Core network** via a **V5.x/VB interface**. + - The bottom Service port function is connected to a **Local exchange**. + +Vertical dotted lines indicate internal connections within the Core shell and between the Service port functions and the network interfaces. + +T1546310-02 + +Functional block diagram of a Non-DBA-OLT showing Core shell, Service shell, ODN interface functions, Transmission MUX/DMUX, ATM cross-connect function, Power, OAM, and Service port functions with their respective network interfaces. + +**Figure 10/G.983.4 – Example of Non-DBA-OLT functional blocks** + +### 5.5.2 DBA-OLT functional block + +The DBA-OLT shares many identical functional blocks with the Non-DBA-OLT (see Figure 11). In short, it is connected to the same networks via the same interfaces as the Non-DBA-OLT. + +![Figure 11/G.983.4 – Example of DBA-OLT functional blocks. The diagram shows a DBA-OLT architecture divided into a Core shell and a Service shell. The Core shell contains ODN interface functions (Static and Dynamic grant assignment), Transmission MUX/DMUX, and ATM cross-connect function. The Service shell contains Service port functions. Below the Core shell are Power and OAM blocks. The Service shell is connected to a Core network via a V5.x/V_B interface and to a Local exchange via another Service port function. The diagram is labeled T1546320-02.](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg) + +The diagram illustrates the functional blocks of a DBA-OLT. It is structured into two main vertical sections: the Core shell and the Service shell. The Core shell is further divided into three vertical columns. The leftmost column contains two 'ODN interface function' blocks; the top one is associated with 'Static grant assignment' and the bottom with 'Dynamic grant assignment', connected by a dashed vertical line. The middle column contains a 'Transmission MUX/DMUX' block. The rightmost column contains an 'ATM cross-connect function' block. Below the Core shell, there are two blocks: 'Power' on the left and 'OAM' on the right. The Service shell, located to the right of the Core shell, contains two 'Service port function' blocks. The top Service port function is connected via a dashed vertical line to a 'Core network' block, with a 'V5.x/VB interface' label between them. The bottom Service port function is connected to a 'Local exchange' block. The entire diagram is enclosed in a large rectangular frame, with the identifier 'T1546320-02' at the bottom right. + +Figure 11/G.983.4 – Example of DBA-OLT functional blocks. The diagram shows a DBA-OLT architecture divided into a Core shell and a Service shell. The Core shell contains ODN interface functions (Static and Dynamic grant assignment), Transmission MUX/DMUX, and ATM cross-connect function. The Service shell contains Service port functions. Below the Core shell are Power and OAM blocks. The Service shell is connected to a Core network via a V5.x/V\_B interface and to a Local exchange via another Service port function. The diagram is labeled T1546320-02. + +**Figure 11/G.983.4 – Example of DBA-OLT functional blocks** + +The difference between the functional blocks of a Non-DBA-OLT and a DBA-OLT is grant assignment on the ODN interface. In a DBA-OLT, the MAC assigns grants to individual T-CONTs on one ODN statically and/or dynamically according to the contract of these T-CONTs and/or their bandwidth request status. Bandwidth request status is collected from ONU/ONT reports and/or OLT surveillance of incoming cells. Moreover, it may be recognized by other methods, for example, bandwidth request from network interfaces. + +## 5.6 Optical distribution network functional block + +In general, the Optical Distribution Network (ODN) provides the optical transport between the ONUs/ONTs and their associated OLT. + +Individual ODNs may be combined and extended through the use of optical amplifiers (see ITU-T Rec. G.982). + +### 5.6.1 Passive optical elements + +The ODN consists of passive optical elements: + +- single-mode optical fibres and cables; +- optical fibre ribbons and ribbon cables; +- optical connectors; +- passive branching components; +- passive optical attenuators; +- splices. + +The specific information required to describe passive optical components is described in ITU-T Rec. G.671. + +The specific information for optical fibres and cable is described in ITU-T Rec. G.652. + +### 5.6.2 Optical interfaces + +In the context of the reference configuration, Figure 12 shows the generic physical configuration of an ODN. + +![Figure 12/G.983.4 – Generic physical configuration of the Optical Distribution Network. The diagram illustrates the connectivity between multiple ONU/ONT units (labeled ONU/ONT1 and ONU/ONTn) on the left and an OLT unit on the right, mediated by an ODN (Optical Distribution Network) block. Reference points R/S are located between the ONU/ONTs and the ODN, while reference point S/R is between the ODN and the OLT. Optical interfaces O_rd and O_ru are at the R/S point; O_ld and O_lu are at the S/R point. Solid lines represent one or more fibres, and dashed lines represent optional protection fibres. The OLT block is marked with T1528150-98.](fa01531ea2c45beeb4036005da3037a4_img.jpg) + +``` + +graph LR + subgraph ONU_Side + ONU1[ONU/ONT1] + ONUn[ONU/ONTn] + end + ODN[ODN] + OLT[OLT] + + ONU1 -- "R/S (O_rd, O_ru)" --- ODN + ONUn -- "R/S (O_rd, O_ru)" --- ODN + ODN -- "S/R (O_ld, O_lu)" --- OLT + ODN -. "Optional Protection" .- OLT + +``` + +$O_{rd}, O_{ru}, O_{ld}, O_{lu}$ Optical interfaces + R and S Reference points + ————— Represent one or more fibres + - - - - - Represent optional protection fibres + +Figure 12/G.983.4 – Generic physical configuration of the Optical Distribution Network. The diagram illustrates the connectivity between multiple ONU/ONT units (labeled ONU/ONT1 and ONU/ONTn) on the left and an OLT unit on the right, mediated by an ODN (Optical Distribution Network) block. Reference points R/S are located between the ONU/ONTs and the ODN, while reference point S/R is between the ODN and the OLT. Optical interfaces O\_rd and O\_ru are at the R/S point; O\_ld and O\_lu are at the S/R point. Solid lines represent one or more fibres, and dashed lines represent optional protection fibres. The OLT block is marked with T1528150-98. + +**Figure 12/G.983.4 – Generic physical configuration of the Optical Distribution Network** + +The two directions for optical transmission in the ODN are identified as follows: + +- downstream direction for signals travelling from the OLT to the ONU/ONT(s); +- upstream direction for signals travelling from the ONU/ONT(s) to the OLT. + +Transmission in downstream and upstream directions can take place on the same fibre and components (duplex/diplex working) or on separate fibres and components (simplex working). + +If additional connectors or other passive devices are needed for ODN rearrangement, they shall be located between S and R and their losses shall be taken into account in any optical loss calculation. + +The ODN offers one or more optical paths between one OLT and one or more ONUs/ONTs. Each optical path is defined between reference points in a specific wavelength window. + +The following optical interfaces are defined in Figure 12: + +- $O_{ru}, O_{rd}$ Optical interface at the reference point R/S between the ONU/ONT and the ODN for the upstream and downstream directions respectively. +- $O_{lu}, O_{ld}$ Optical interfaces at the reference point S/R between the OLT and the ODN for the upstream and downstream directions respectively. + +At the physical layer, the interfaces may require more than one fibre, e.g. for separation of transmission directions or different types of signals (services). + +Specification of the optical interfaces ( $O_{ru}, O_{rd}, O_{lu}, O_{ld}$ ) are defined in clause 8. + +The optical properties of the ODN shall enable the provisioning of any presently foreseeable service, without the need of extensive modifications to the ODN itself. This requirement has an impact on the properties of the passive optical components that constitute the ODN. A set of essential requirements, which have a direct influence on the optical properties of the ODN, are identified as follows: + +- *optical wavelength transparency*: devices, such as optical branching devices, which are not intended to perform any wavelength-selective function, shall be able to support transmission of signals at any wavelength in the 1310 nm and 1550 nm regions; +- *reciprocity*: reversal of input and output ports shall not cause significant changes of the optical loss through the devices; +- *fibre compatibility*: all optical components shall be compatible with single-mode fibre as specified in ITU-T Rec. G.652. + +#### 5.6.2.1 Optical Distribution Network model loss calculations + +This is described in ITU-T Rec. G.982. + +#### 5.6.2.2 Optical Distribution Network model loss calculation technique + +This is described in ITU-T Rec. G.982. + +# 6 Services + +The high-speed access systems described in this Recommendation could provide the complete range of all currently known and new services being discussed for the residential subscribers and business customers. These services could include: + +- Data communications, including LAN interconnection. +- Private Line services. +- Telephony. +- Entertainment video distribution and video conferencing. +- Electronic commerce and data transfer + +These services imply a broad range of network requirements that include: + +- bit rate; +- symmetry/asymmetry; +- delay; +- delay variation; +- transparent Virtual Paths; +- support for ATC/QoS. + +In particular, even if DBA is installed to economize network resources, ATM services with any ATC/QoS over PON can be provided without degradation of criteria for quality as described in ITU-T Rec. I.356. Moreover, DBA produces benefits for carrying variable bit rate traffic, such as bursty traffic (e.g. SBR and GFR), which may be particularly useful for data communication and video communication. + +What specific services should be provided differs among operators and depends heavily on the particular regulatory conditions in each operator's markets, as well as on market potential. How these services are delivered in a cost effective way is a function not only of legal conditions but also of factors including existing telecommunications infrastructure, dwelling distribution, customer density and residential/business customers mix. + +In spite of this varied market background there are some features that have been perceived as common to all parties. They can be summarized as follows: + +- Some services require bit rates higher than those supported by PSTN and basic ISDN. These bit rates are best delivered on fibre based or fibre hybrid networks. +- As the services evolve and newer services are introduced the bandwidth and management requirements will increase. This requires the access network to be flexible and easily upgraded. + +# 7 User network interface and service node Interface + +The specific information is described in ITU-T Rec.G.983.1. + +# 8 Optical network requirements + +## 8.1 Layered structure of the optical network + +Layering is based on ITU-T Rec. G.982. The ODN refers to the fibre distribution network based on passive optical splitter branching components. The OAN is the system between the "V" and "T" reference points (Figure 7). The ONU/ONT may have an adaptation function (AF), for digital subscriber line (DSL) transmission over copper to the customer. The OAN is managed as one element, through a Q3 management interface. + +The protocol reference model is divided into physical medium, TC, and path layer (ITU-T Recs. G.902, I.326, and G.982). As an example an ATM-PON is shown in Table 1. In the ATM-PON network, path layer corresponds to the VP (Virtual Path) of the ATM layer. + +**Table 1/G.983.4 – Layered structure of ATM-PON Network** + +| | | | | | +|------------------------------------------------------------------------------|----------|------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--| +| Path layer | | | Refer to ITU-T Recs. I.732 and I.326 | | +| Transmission medium layer (Note) | TC layer | Adaptation | Refer to ITU-T Recs. I.732 and I.432 | | +| | | PON transmission | Ranging based on ITU-T Rec. G.983.1 and DBA
MAC
Cell slot allocation based on statistical bandwidth assignment and DBA
Detection of offered traffic load for DBA
Bandwidth allocation based on traffic contract and bandwidth request
Privacy and security
Frame alignment
Burst synchronization
Bit/byte synchronization | | +| Physical medium layer | | | E/O adaptation
Wavelength division multiplexing
Fibre connection | | +| NOTE – The transmission medium layer must provide the related OAM functions. | | | | | + +The TC layer is divided into PON transmission and adaptation sublayers, which correspond to the transmission convergence sublayer of the B-ISDN (Broadband Integrated Services Digital Network) in ITU-T Rec. I.321. The PON transmission sublayer terminates the required transmission function + +on the ODN. The PON specific functions are terminated by the PON transmission sublayer, and are not seen from the adaptation sublayer. The PON transmission sublayer includes MAC functions for cell slot allocation and bandwidth allocation. DBA is positioned as a part of the MAC functions in the PON transmission sublayer. As shown in Table 1, MAC provides cell slot allocation and bandwidth allocation according to the traffic contract based on ITU-T Rec. G.983.1. However, to support DBA, it provides these functions based on traffic load in addition to functions based on ITU-T Rec. G.983.1. Moreover, the Detection of Offered Traffic Load function is required to support the above-mentioned functions based on traffic load, which can be changed dynamically, for DBA. Additionally, Ranging in the PON transmission sublayer and some extensions of procedures in ITU-T Rec.G.983.1 are specified. + +## **8.2 Physical medium dependent layer requirements for the ATM-PON** + +The specific information is described in ITU-T Rec. G.983.1. + +## **8.3 Transmission convergence layer requirements for the ATM-PON** + +The specific information is described in ITU-T Rec. G.983.1. + +### **8.3.1 Point-to-multipoint capacities for downstream and upstream** + +The specific information is described in ITU-T Rec. G.983.1. + +### **8.3.2 Maximum payload capacities for downstream and upstream** + +The specific information is described in ITU-T Rec. G.983.1. + +### **8.3.3 Downstream interface** + +The specific information is described in ITU-T Rec. G.983.1. + +### **8.3.4 Upstream interface** + +The Physical Layer overhead includes: PLOAM cells, minislots for the MAC channel and overhead bytes which are added in front of each upstream ATM cell, PLOAM cell or minislot. + +The transfer capacity for the 155.52 Mbit/s interface has an upper limit of 147.2 Mbit/s ( $155.52 \times 53/56$ Mbit/s). Some extra bandwidth is allocated by the OLT for the upstream PLOAM channel and the minislots for MAC channel. Mini-slots can be transferred from several ONUs/ONTs to the OLT synchronously. Bandwidth for minislots can be programmable according to reporting capability. For example, if a large amount of bandwidth is reserved for minislots, the OLT can receive and process the information that is sent by the ONUs/ONTs quickly, although bandwidth for other uses is reduced. This amount of bandwidth reserved for minislots should be determined by several factors, including network configuration, service guidelines and the implementation of OLTs and ONUs/ONTs. Moreover, the OLT can assign multiple minislots to an ONU/ONT in order to change the reporting frequency of any ONU/ONT. Therefore, the ONU/ONT must also manage the multiple minislots. Detailed examples are described in 8.3.5.10.1.3. The number of minislots assigned is also determined by multiple factors. + +The upstream transfer capacity is shared between the ONUs/ONTs and/or T-CONTs based on their allocated upstream bandwidth. + +### **8.3.5 Transport specific TC interface** + +#### **8.3.5.1 Frame structure** + +The downstream interface structure for both 155.52 Mbit/s and 622.08 Mbit/s consists of a continuous stream of timeslots, each timeslot containing 53 octets of an ATM cell or a PLOAM cell. + +Every 28th timeslot a PLOAM cell is inserted. A downstream frame contains two such PLOAM cells and is 56 slots long for the 155 Mbit/s downstream case. For the 622 Mbit/s case, it contains eight PLOAM cells and is 224 slots long. + +In the upstream direction the frame contains 53 timeslots of 56 bytes. The OLT requests an ONU/ONT to transmit an ATM cell via grants conveyed in downstream PLOAM cells. At a programmable rate, the OLT requests an ONU/ONT to transmit a PLOAM cell or a minislot. The upstream PLOAM rate depends on the required functionality contained in these PLOAM cells. These PLOAM cells may transfer information concerning the status of ONUs/ONTs in order to support DBA. The minimum PLOAM rate per ONU/ONT is one PLOAM cell every 100 ms. The OLT defines the bandwidth allocated to the upstream minislots. Although allocation of minislots can be programmable, several values will be recommended in order to obtain adequate performance. + +The PLOAM cells are used to convey the Physical Layer OAM information. In addition, downstream PLOAM cells carry the grants used by the ONUs/ONTs for upstream access. + +A divided\_slot occupies a complete upstream timeslot, and contains a number of minislots from a set of ONUs/ONTs. The MAC protocol based on reporting status uses minislots to transfer to the OLT the status of the ONUs/ONTs in order to implement DBA. This serves as the mandatory method for reporting T-CONT status in SR-ONUs/ONTs. Therefore, since an OLT may expect reports from all of the SR-ONUs/ONTs on one physical interface with minimized time lag, divided\_slots may be allocated consecutively to gather all of the reports within a short period. + +The described frames, cells, bytes and bits are transmitted in the following order referring to their numbering: frames are transmitted in ascending order, cells within a frame are transmitted in ascending order, the bytes within a cell are transmitted in ascending order and within a byte, the most significant bit is transmitted first. The most significant bit in a byte is bit number 1 and the least significant bit is bit number 8, so for example the MSB of 0b10101010 is equal to 1. + +##### **8.3.5.1.1 Frame structure for symmetric PON** + +The specific information is described in ITU-T Rec. G.983.1. + +##### **8.3.5.1.2 Frame structure for 622/155 Mbit/s PON** + +The specific information is described in ITU-T Rec. G.983.1. + +##### **8.3.5.1.3 Time relation downstream – upstream frame** + +The specific information is described in ITU-T Rec. G.983.1. + +#### **8.3.5.2 Physical layer cell identification** + +The specific information is described in ITU-T Rec. G.983.1. + +#### **8.3.5.3 Downstream PLOAM structure** + +The specific information is described in ITU-T Rec. G.983.1. + +##### **8.3.5.3.1 PLOAM cell termination** + +The specific information is described in ITU-T Rec. G.983.1. + +##### **8.3.5.3.2 PLOAM identification** + +The specific information is described in ITU-T Rec. G.983.1. + +##### **8.3.5.3.3 Frame synchronization** + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.3.4 Synchronization field (SYNC1-SYNC2) + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.3.5 Grants + +Each PLOAM cell is filled with 27 grants. These grants are used by the ONUs/ONTs for access to the upstream fibre. Per frame only 53 are needed. The 53 grants are mapped in the first two PLOAM cells of the downstream frame. All 53 grants are non-idle grants. The last grant of the second PLOAM cell is filled with an idle grant. The grant fields of the six remaining PLOAM cells for the 622 Mbit/s downstream case are all filled with idle grants and hence will not be used by the ONU/ONT. The length of a grant is 8 bits and the following types are defined in Table 2. + +**Table 2/G.983.4 – Specification of the grants** + +| Type | Encoding | Definition | +|--------------------|---------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Data grant | Any value except
1111 1101
1111 1110
1111 1111 | For indicating an upstream T-CONT-specific data grant. The value of the first data grant is assigned to the ONU/ONT during the ranging protocol using the grant_allocation message. The ONU/ONT can send an OMCI cell by this first assigned data grant to maintain backward compatibility with existing ONU/ONT specified in ITU-T Rec. G.983.1. Moreover the values of the additional data grant are assigned to the T-CONT in an operating state using the additional_grant_allocation message. The T-CONT can send a data cell by first or additional data grant. The ONU/ONT can send a data cell or an idle cell if no data cell is available. | +| PLOAM grant | Any value except
1111 1101
1111 1110
1111 1111 | For indicating an upstream ONU/ONT-specific PLOAM grant. The value of the PLOAM grant is assigned to the ONU/ONT during the ranging protocol using the grant_allocation message. The ONU/ONT always sends a PLOAM cell in response to this grant. | +| Divided_slot grant | Any value except
1111 1101
1111 1110
1111 1111 | For indicating an upstream group of ONU/ONT specific divided_slot grants. The OLT allocates the grant to a set of ONUs/ONTs using the Divided_slot_grant_configuration message. Each ONU/ONT of this set sends a minislot. The divided slot is used to report a queue length of the T-CONT to the OLT. The ONU/ONT processes one or more divided_slot grants up to the maximum specified by its Maximum_divided_slot_grants parameter. | +| Reserved grants | Any value except
1111 1101
1111 1110
1111 1111 | In a future version of this Recommendation other grant types will be used for specific data grants (e.g. to address a specific ONU/ONT interface or QoS class). | +| Ranging grant | 1111 1101 | Used for the ranging process. The response to this grant is described in the ranging protocol. | +| Unassigned grant | 1111 1110 | For indicating an unused upstream slot. | +| Idle grant | 1111 1111 | For decoupling the downstream PLOAM rate from the upstream cell rate. These grants are ignored by the ONU/ONT. | + +The OLT shall be able to address 32 ONUs/ONTs at the same time on a PON. Optionally the OLT may address up to 64 ONUs/ONTs on a single PON. + +##### 8.3.5.3.6 Grants protection + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.3.7 MESSAGE field + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.3.8 Bit Interleaved Parity (BIP) + +The specific information is described in ITU-T Rec. G.983.1. + +#### 8.3.5.4 Upstream PLOAM structure + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.4.1 PLOAM cell termination + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.4.2 PLOAM identification + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.4.3 MESSAGE field + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.4.4 Bit Interleaved Parity (BIP) + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.4.5 Laser Control Field (LCF) + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.3.5.4.6 Receiver Control Field (RXCF) + +The specific information is described in ITU-T Rec. G.983.1. + +#### 8.3.5.5 Divided\_slots + +An upstream slot can contain a divided\_slot. The divided\_slot fits into one upstream slot and contains a number of minislots coming from a set of ONUs/ONTs. The OLT assigns one divided\_slot grant to this set of ONUs/ONTs for sending their minislots. The format of the divided\_slot is shown in Figure 13. + +![Diagram showing the hierarchical structure of an upstream frame, upstream slot, divided slot, and minislot.](275d1aff687b9dd7f744df07ae877422_img.jpg) + +The diagram illustrates the format of a divided slot within an upstream frame. At the top level, an 'Upstream frame' is shown as a sequence of slots, with slots 1, 2, k (highlighted), and 53 visible. Slot k is an 'upstream slot' that contains a 'Divided slot'. The 'Divided slot' is further broken down into multiple 'minislot' units originating from different ONUs/ONTs, labeled ONU/ONTx, ONU/ONTy, and ONU/ONTz. Each 'minislot' consists of a '3 upstream overhead bytes' section followed by a 'minislot payload, 1 to 53 bytes'. The diagram uses nested boxes and lines to show the containment hierarchy. A small label 'T1528250-98' is present in the bottom right corner of the diagram area. + +Diagram showing the hierarchical structure of an upstream frame, upstream slot, divided slot, and minislot. + +Figure 13/G.983.4 – Format of divided\_slot + +The minislot is used to report the queue length of the T-CONT to the OLT in the case of SR-ONUs/ONTs. + +The length of the minislot is an integral number of bytes, ranging from a minimum of 5 to a maximum of 56 bytes. Each minislot is composed of the physical layer overhead bytes, one or more T-CONT report bytes, and CRC-8 trailer. + +NOTE – For exceptionally long minislots where the payload is greater than 15 bytes, additional CRC-8s must be inserted. + +The three overhead bytes have the same definition as stated in Table 6/G.983.1. + +The minislot payload is protected by a Cyclic Redundancy Check (CRC). The formula for generating the CRC polynomial for the minislot payload is: + +$$g(x) = x^8 + x^2 + x + 1$$ + +#### **8.3.5.6 Churning** + +The specific information is described in ITU-T Rec. G.983.1. + +#### **8.3.5.7 Verification function** + +The specific information is described in ITU-T Rec. G.983.1. + +#### **8.3.5.8 VP/VC for higher layer** + +The specific information is described in ITU-T Rec. G.983.1. + +#### **8.3.5.9 Duplex PON system** + +In the case of a duplex system where a redundant PON protects the active PON, protection switching will be activated by using specified messages in PLOAM cells. This sequence will require that the line numbers of the OLT must be exactly the same as those of the ONU/ONT. This line identifier is assigned to a transmitter based on the interconnection scheme of OLTs with ONUs/ONTs. The line identifier is sent to both the OLT and the ONU/ONT to check whether the received line identifier is the same as its own identifier. This is defined as the PON Section Trace (PST) message. Then individual equipment can verify that it is connected to the proper transmitter. If the received line number differs from the expected line number, the equipment generates an alarm, MIS (Link Mismatching) to notify the operator or user of the problem. + +The PST messages include the K1 and K2 bytes as they are specified in ITU-T Rec. G.783 for performing Automatic Protection Switching. + +In case of an unprotected system, link mismatching is optional. + +##### **8.3.5.9.1 Relationship between DBA and protection functions** + +DBA has some impacts on protection functions in the cases of protection Types C and D as defined in Appendix IV/G.983.1. These impacts and outstanding operations in DBA will be discussed in the future. For Types A and B, DBA does not have any impact because each ONU/ONT has only one interface to the OLT. However, in the cases of Types C and D, some additional capabilities in DBA to support the protection functions may be specified, such as provisioned parameters, identification of T-CONTs, and grant allocation. + +The typical example is shown in Figure 14. In this example, both side-0 and side-1 are used in the normal state as shown in Figure 14 a). When a failure occurs between the splitter and the ONU/ONT's working side, the other side's extra bandwidth is assigned for the ONU/ONT as shown in Figure 14 b). + +![Bandwidth allocation diagram for normal state. A vertical double-headed arrow on the left is labeled 'Maximum Bandwidth per line'. The diagram is divided into two columns: 'Side 0' and 'Side 1'. 'Side 0' contains three boxes: 'unused' at the top, 'ONU/ONT#1's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#3's Minimum BW + Available BW for DBA' at the bottom. 'Side 1' contains three boxes: 'unused' at the top, 'ONU/ONT#2's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#5's Minimum BW + Available BW for DBA' at the bottom. Dashed lines connect the bottom boxes of Side 0 and Side 1 to the top 'unused' boxes of the opposite side.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +Bandwidth allocation diagram for normal state. A vertical double-headed arrow on the left is labeled 'Maximum Bandwidth per line'. The diagram is divided into two columns: 'Side 0' and 'Side 1'. 'Side 0' contains three boxes: 'unused' at the top, 'ONU/ONT#1's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#3's Minimum BW + Available BW for DBA' at the bottom. 'Side 1' contains three boxes: 'unused' at the top, 'ONU/ONT#2's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#5's Minimum BW + Available BW for DBA' at the bottom. Dashed lines connect the bottom boxes of Side 0 and Side 1 to the top 'unused' boxes of the opposite side. + +![Network topology diagram for normal state. An 'Optical splitter' is connected to two OLTs: 'OLT(Side 0)' and 'OLT(Side 1)'. The OLTs are connected to the splitter via 'cell' units. The splitter is connected to multiple ONUs/ONTs: 'ONU/ONT#1 (Side 0)', 'ONU/ONT#1 (Side 1)', 'ONU/ONT#2 (Side 0)', 'ONU/ONT#2 (Side 1)', 'ONU/ONT#3 (Side 0)', 'ONU/ONT#3 (Side 1)', and 'ONU/ONT#5 (Side 0)'. Each ONU/ONT is connected to the splitter via a 'cell' unit. Dashed lines connect the ONUs/ONTs to the splitter.](7f5df81190b8dc50dad2604562ae0715_img.jpg) + +Network topology diagram for normal state. An 'Optical splitter' is connected to two OLTs: 'OLT(Side 0)' and 'OLT(Side 1)'. The OLTs are connected to the splitter via 'cell' units. The splitter is connected to multiple ONUs/ONTs: 'ONU/ONT#1 (Side 0)', 'ONU/ONT#1 (Side 1)', 'ONU/ONT#2 (Side 0)', 'ONU/ONT#2 (Side 1)', 'ONU/ONT#3 (Side 0)', 'ONU/ONT#3 (Side 1)', and 'ONU/ONT#5 (Side 0)'. Each ONU/ONT is connected to the splitter via a 'cell' unit. Dashed lines connect the ONUs/ONTs to the splitter. + +a) Normal state + +![Bandwidth allocation diagram after failure. A vertical double-headed arrow on the left is labeled 'Maximum Bandwidth per line'. The diagram is divided into two columns: '(Side 0)' and '(Side 1)'. '(Side 0)' contains three boxes: 'unused' at the top, 'ONU/ONT#3's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#4's Minimum BW + Available BW for DBA' at the bottom. '(Side 1)' contains three boxes: 'unused' at the top, 'ONU/ONT#1's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#2's Minimum BW + Available BW for DBA' at the bottom. Dashed lines connect the bottom boxes of Side 0 and Side 1 to the top 'unused' boxes of the opposite side.](6629e8a87e7552e2454b7c3e9f6d73a0_img.jpg) + +Bandwidth allocation diagram after failure. A vertical double-headed arrow on the left is labeled 'Maximum Bandwidth per line'. The diagram is divided into two columns: '(Side 0)' and '(Side 1)'. '(Side 0)' contains three boxes: 'unused' at the top, 'ONU/ONT#3's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#4's Minimum BW + Available BW for DBA' at the bottom. '(Side 1)' contains three boxes: 'unused' at the top, 'ONU/ONT#1's Minimum BW + Available BW for DBA' in the middle, and 'ONU/ONT#2's Minimum BW + Available BW for DBA' at the bottom. Dashed lines connect the bottom boxes of Side 0 and Side 1 to the top 'unused' boxes of the opposite side. + +![Network topology diagram after failure. An 'Optical splitter' is connected to two OLTs: 'OLT(Side 0)' and 'OLT(Side 1)'. The OLTs are connected to the splitter via 'cell' units. The splitter is connected to multiple ONUs/ONTs: 'ONU/ONT#1 (Side 0)', 'ONU/ONT#1 (Side 1)', 'ONU/ONT#2 (Side 0)', 'ONU/ONT#2 (Side 1)', 'ONU/ONT#3 (Side 0)', 'ONU/ONT#3 (Side 1)', and 'ONU/ONT#5 (Side 0)'. Each ONU/ONT is connected to the splitter via a 'cell' unit. Dashed lines connect the ONUs/ONTs to the splitter. A 'Failure' is indicated by a cross on the line between 'ONU/ONT#1 (Side 0)' and the 'Optical splitter'.](04cfca33e3fc26513abe649d7474f733_img.jpg) + +Network topology diagram after failure. An 'Optical splitter' is connected to two OLTs: 'OLT(Side 0)' and 'OLT(Side 1)'. The OLTs are connected to the splitter via 'cell' units. The splitter is connected to multiple ONUs/ONTs: 'ONU/ONT#1 (Side 0)', 'ONU/ONT#1 (Side 1)', 'ONU/ONT#2 (Side 0)', 'ONU/ONT#2 (Side 1)', 'ONU/ONT#3 (Side 0)', 'ONU/ONT#3 (Side 1)', and 'ONU/ONT#5 (Side 0)'. Each ONU/ONT is connected to the splitter via a 'cell' unit. Dashed lines connect the ONUs/ONTs to the splitter. A 'Failure' is indicated by a cross on the line between 'ONU/ONT#1 (Side 0)' and the 'Optical splitter'. + +b) After the failure occurred + +T1546330-02 + +BW Bandwidth + +**Figure 14/G.983.4 – Relationship between DBA and protection function** + +#### 8.3.5.10 MAC protocol + +The MAC layer in the OLT needs specific information to fairly allocate bandwidth between ONUs/ONTs on a PON. The MAC protocol is also referred to as the DBA protocol if the OLT supports dynamic assignment of bandwidth in the upstream direction. The MAC protocol is implemented in the PON transmission part of the TC layer described in 8.1. As the MAC protocol, DBA should ensure transparency to higher layers, such as the ATM layer. In short, ATM cells should be transported through and across the PON in a completely transparent manner without any impact on ATC/QoS. + +When a DBA-OLT supports SR-ONUs/ONTs, the required information is mapped into the payload field of the minislot using the mandatory reporting method. An ONU/ONT is allowed to send this minislot after receiving a divided\_slot grant. Specifically, the Divided\_Slot\_Grant\_configuration message is used for this type of grant, and the length and offset of the upstream minislot are carried in the same message. The MAC also includes a bandwidth allocation function based on conventional static grant assignment according to the traffic contract. + +##### **8.3.5.10.1 DBA protocol** + +The DBA protocol consists of three strategies, referred to as NSR, SR, and Hybrid types. The NSR type strategy is invoked by monitoring traffic in the OLT. The SR type strategy is invoked by status reports sent from ONUs/ONTs to the OLT. The Hybrid strategy is invoked by both monitoring traffic in the OLT and processing in the OLT the status reports from ONUs/ONTs. This Recommendation does not specify detailed mechanisms or algorithms for these strategies, but rather requirements and the required interfaces at reference points IFPON (S/R and R/S) are described (see clause 5.2). The detailed mechanisms and the scheme for how to combine NSR and SR types in the Hybrid strategy are out of scope for this Recommendation. + +###### **8.3.5.10.1.1 Working unit for DBA** + +The DBA protocol is executed on every T-CONT active in a SR-ONU/ONT. Operations and assigned resources among T-CONTs can be independent from each other. In short, one or more T-CONTs can be defined in one ONU/ONT, if all of the T-CONTs on the reference point S/R can be identified by grant codes specified in 8.3.5.3.5. T-CONTs do not interfere with each other. + +###### **8.3.5.10.1.2 DBA protocol with OLT monitoring** + +This clause describes how an OLT can collect the bandwidth request information from the T-CONTs in its associated ONUs/ONTs without using status reporting. The OLT inspects each incoming cell from a specific T-CONT in a predefined time frame. For example, the OLT calculates the utilization rate of the currently assigned bandwidth by monitoring the number of effective received cells from specific T-CONTs, and uses this value as the bandwidth request information. + +These mechanisms are applied to cases where a DBA-OLT supports NSR-ONUs/ONTs and/or SR-ONUs/ONTs that may suspend reporting. + +Moreover, if SR-ONUs/ONTs report status, the OLT can work based on monitoring results independently of these reports if the OLT concludes that the monitoring approach is more suitable for the current situation. For example, when the ONU/ONT reports are insufficient, the monitoring operation can be invoked. + +###### **8.3.5.10.1.3 DBA protocol with status reporting** + +This clause describes how an SR-ONU/ONT explicitly reports to its DBA-OLT PON interface. Since a number of ONUs/ONTs and their DBA T-CONTs may report queue lengths of T-CONT buffers, it is imperative to balance the amount of information with the upstream bandwidth consumption of these reports. Reporting methods and reported information are specified as follows. + +###### **8.3.5.10.1.3.1 Reporting minislot format** + +Minislots contained in the divided\_slot are specified using the mandatory status reporting method. The reporting cycle is one of the parameters that should be provisioned by the operators to obtain suitable performance. + +Generally the OLT will generate divided\_slot grants to request a queue length for the specified ONU/ONT according to the service requirements. When an ONU/ONT recognizes a divided\_slot grant, the ONUs/ONTs can transfer information in a minislot in the divided\_slot. This minislot contains the queue length for every T-CONT using non-linear coding and CRC-8. + +In this queue length reporting, fields in a divided\_slot are identified by two offset values, minislot\_offset and field\_offset, as shown in Figure 15. The minislot\_offset identifies the location of a minislot for the ONU/ONT. It is specified by a Divided\_Slot\_Grant\_configuration message, which is one of the PLOAM messages and is mentioned in 8.3.8. The field\_offset identifies the location of a T-CONT in the minislot, when two or more T-CONTs are specified in an ONU/ONT. It can be specified by the Additional\_Grant\_Allocation message. A minislot in a divided\_slot can report queue length for up to 49 T-CONTs, if the default reported information described in 8.3.5.10.1.3.2 is used. However, if 50 or more T-CONTs are specified in an ONU/ONT, multiple divided\_slots can be allocated to report the queue lengths. In this case, mapping between these slots and the reporting field for each T-CONT should be managed by the OLT. On the other hand, when the configuration of T-CONTs is changed and a T-CONT is deactivated, the queue length for this T-CONT should not be reported. In this case, the reporting field for this T-CONT is removed according to the procedures described in 8.6.3. + +![Figure 15/G.983.4 – Relationship between a divided_slot and minislots. The diagram shows a horizontal bar labeled 'One slot' containing several minislots: 'Minislot for ONU/ONT_k', 'Minislot for ONU/ONT_i', 'Minislot for ONU/ONT_j', and 'Minislot for ONU/ONT_n'. The 'minislot_offset' is indicated by a double-headed arrow from the start of the slot to the start of the first minislot. The 'Length' is indicated by a double-headed arrow from the start of the first minislot to the start of the second. Below the second minislot, a callout shows its internal structure: '3 bytes overhead', a small box for 'field_offset', 'Minislot payload', and '1 byte CRC'.](67114ecf6da13c97a89aeff0d86885d5_img.jpg) + +Figure 15/G.983.4 – Relationship between a divided\_slot and minislots. The diagram shows a horizontal bar labeled 'One slot' containing several minislots: 'Minislot for ONU/ONT\_k', 'Minislot for ONU/ONT\_i', 'Minislot for ONU/ONT\_j', and 'Minislot for ONU/ONT\_n'. The 'minislot\_offset' is indicated by a double-headed arrow from the start of the slot to the start of the first minislot. The 'Length' is indicated by a double-headed arrow from the start of the first minislot to the start of the second. Below the second minislot, a callout shows its internal structure: '3 bytes overhead', a small box for 'field\_offset', 'Minislot payload', and '1 byte CRC'. + +minislot\_offset To identify the starting point for particular ONU/ONT minislot +field\_offset To identify the starting point for particular TCONT within one ONU/ONT minislot + +**Figure 15/G.983.4 – Relationship between a divided\_slot and minislots** + +###### 8.3.5.10.1.3.2 Reported information + +This clause describes reported information from SR-ONUs/ONTs using minislots. The reported information should not be limited by any DBA algorithms that are adopted or restricted by the set-up values of bandwidth types. Moreover, the bandwidth for any T-CONT should be adjustable to any value based on the reported information. + +SR-ONUs/ONTs shall report the queue length of their T-CONTs using non-linear coding, when requested to do so by their OLT. The queue length is the sum of the total number of cells in all the class buffers that are connected to a particular T-CONT in an ONU/ONT. All equipment must support the format type, as shown in Figure 16. + +The information conveyed in the minislot from the ONU/ONT should be protected by the CRC, and the information should be used only when the CRC check is correct. + +Additional reported information may be useful. The additional reported information and the negotiation procedure to use additional reported information are described as an informative option in Appendix II. In Appendix II, standard reported information is dealt with as "default reporting field meaning" and the combination of standard reported information and additional reported information are dealt with as "optional report field meanings". Even if the OLT and the ONU/ONT have applied optional report field definitions in Appendix II, all OLTs and ONUs/ONTs must support the standard reported information definitions or "default reporting field meaning" in Appendix II. + +![Figure 16/G.983.4 – The detailed minislot format for one ONU/ONT. The diagram shows a minislot structure with 3 bytes overhead, followed by a series of 1-byte T_CONT reporting fields (T_CONT#1, T_CONT#2, ..., T_CONT#14, T_CONT#15, T_CONT#16) and CRC bytes. The overhead is 3 bytes, and there are 14 T-CONTs. The CRC is inserted after every 14 bytes of payload. The diagram shows the first 14 T-CONTs, followed by a CRC, then T_CONT#15, T_CONT#16, and another CRC.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +One minislot for ONU/ONTi + +| | | | | | | | | | +|------------------|--------------------|--------------------|-------|---------------------|--------|---------------------|---------------------|--------| +| 3 bytes overhead | 1 Byte | 1 Byte | ----- | 1 Byte | 1 Byte | 1 Byte | 1 Byte | 1 Byte | +| | T_CONT#1 reporting | T_CONT#2 reporting | | T_CONT#14 reporting | CRC | T_CONT#15 reporting | T_CONT#16 reporting | CRC | + +Figure 16/G.983.4 – The detailed minislot format for one ONU/ONT. The diagram shows a minislot structure with 3 bytes overhead, followed by a series of 1-byte T\_CONT reporting fields (T\_CONT#1, T\_CONT#2, ..., T\_CONT#14, T\_CONT#15, T\_CONT#16) and CRC bytes. The overhead is 3 bytes, and there are 14 T-CONTs. The CRC is inserted after every 14 bytes of payload. The diagram shows the first 14 T-CONTs, followed by a CRC, then T\_CONT#15, T\_CONT#16, and another CRC. + +T1546350-02 + +**Figure 16/G.983.4 – The detailed minislot format for one ONU/ONT** + +One CRC is inserted for every 14 bytes of minislot payload at the ONU/ONT. The CRC shall be the remainder (modulo 2) of the division by the polynomial $x^8 + x^2 + x + 1$ into the report fields between the preceding CRC or the beginning of the minislot and the CRC itself. If the minislot payload is not evenly divisible into 14 byte segments, a CRC byte should be appended to the end of the minislot payload. An example of the detailed minislot format is shown in Figure 16. The maximum number of T-CONTs that can be supported in one minislot is 49 (the whole slot = 56 byte = 3 bytes overhead + 3 \* 14 bytes (T-CONTs) + 3 bytes CRC + 7 T-CONTs + 1 CRC). This situation only happens when one complete slot is assigned to one ONU/ONT. This may be caused by one ONU/ONT having 49 or more activated T-CONTs. + +###### 8.3.5.10.1.3.3 Report field coding + +The default minislot format is shown in Figure 16 in 8.3.5.10.1.3.2. The reported 1 byte queue length is the non-linear coded value of the actual number of cells in a T-CONT of a specific ONU/ONT. The mapping between the number of cells (the input), the 1 byte value (the code) and the decoded message (the output) is given in Table 3 as default code points. Note that the decoded output is effectively rounded up to the largest value that could have resulted in that particular code point. This property ensures that the coding error is always positive. + +**Table 3/G.983.4 –Non-linear coding for report field of minislot** + +| Queue Length | Binary Input (ONU/ONT) | Coding of octet (minislot) | Binary Output (OLT) | +|--------------|------------------------|----------------------------|---------------------| +| 0-127 | 00000000abcdefg | 0abcdefg | 00000000abcdefg | +| 128-255 | 00000001abcdeFx | 10abcdef | 00000001abcdef1 | +| 256-511 | 0000001abcdeFxx | 110abcde | 0000001abcde111 | +| 512-1023 | 000001abcdFxxxx | 1110abcd | 000001abcd11111 | +| 1024-2047 | 00001abcFxxxxxx | 11110abc | 00001abc1111111 | +| 2048-4095 | 0001abFxxxxxxxxxx | 111110ab | 0001ab111111111 | +| 4096-8191 | 001axFxxxxxxxxxxx | 1111110a | 001a11111111111 | +| >8191 | 001111111111111 | 11111110 | 011111111111111 | +| Reserved | N/A | 11111111 | N/A | + +The code point described in Table 3 may be changed according to the service situation and the implementation of OLTs and ONUs/ONTs. However, alternative code points have not been specified in this Recommendation. + +NOTE – The reserved value (0xFF) is used to indicate an unassigned report field. + +###### 8.3.5.10.1.4 DBA protocol with OLT monitoring and status reporting + +A DBA-OLT can combine NSR and SR strategies and then apply them to SR-ONUs/ONTs. For example, even if an SR-ONU/ONT reports status, the DBA-OLT is not required to use the information and may instead use cell monitoring results to update the bandwidth. The schemes for how to combine both types depend on the service situation and implementation. A DBA-OLT can select schemes based on either NSR or SR strategies, or the combination of NSR and SR strategies in every SR-ONU/ONT associated with one physical ATM-PON interface. + +###### 8.3.5.10.1.5 DBA and upstream congestion of the OLT NNI + +As a future extension, the DBA protocol may operate based on not only the requested bandwidth of the T-CONTs and the available bandwidth of the upstream PON links but also the upstream congestion on the OLT NNIs as shown in Figure 17. The DBA-OLT could decrease the grants to T-CONTs carrying VPCs/VCCs that are congested upstream to their assured bandwidth level. The DBA-OLT could also intelligently control distribution of additional bandwidth available in the PON to an SR-ONU/ONT / T-CONT. In short, there are two congestion patterns such as a) and b) in Figure 17. In the first case, the bandwidth for T-CONTs included in the congested NNI may be reduced. However, in the second case, since the group that detected congestion on the network interface cannot band T-CONTs on ATM-PON physical links, blocking the upstream traffic carried by some T-CONTs may be caused as in Figure 17 (b). To avoid this blocking, some mechanisms and implementations can be studied. However, these are not included in this Recommendation. + +![Figure 17/G.983.4 – Configuration of T-CONTs on the network interface. The diagram shows two scenarios (a and b) of T-CONT connections to an OLT's network interfaces (Network IF #1 and Network IF #2) via an ATM-PON interface. In (a), connections are banded. In (b), connections are disbanded due to congestion on IF #1.](838c31609fac483fa2c01c7896a2fd6d_img.jpg) + +The diagram illustrates the configuration of T-CONTs on the network interface of an OLT. It is divided into two parts, (a) and (b), showing different congestion scenarios. + +**a) Banded connections in every T-CONT on a network IF** + +In this scenario, four T-CONTs (T-CONT#1, T-CONT#2, T-CONT#3, T-CONT#4) are connected to the OLT via an ATM-PON interface. The OLT has two network interfaces: Network IF #1 and Network IF #2. Connections from T-CONT#1 and T-CONT#2 are banded to Network IF #1. Connections from T-CONT#3 and T-CONT#4 are banded to Network IF #2. A congestion point is indicated by a starburst symbol on Network IF #1. Arrows labeled "Congested TCs" point to T-CONT#1 and T-CONT#2. + +**b) Disbanded connections in every T-CONT on a network IF** + +In this scenario, the same four T-CONTs are connected to the OLT. However, due to congestion on Network IF #1 (indicated by a starburst), the connections for T-CONT#1, T-CONT#2, and T-CONT#3 are shown as being blocked or disbanded. A box labeled "Blocked connections by congestion on IF #1" points to these three connections. T-CONT#4 remains connected to Network IF #2. Arrows labeled "Congested TCs" point to T-CONT#1 and T-CONT#2. + +Figure 17/G.983.4 – Configuration of T-CONTs on the network interface. The diagram shows two scenarios (a and b) of T-CONT connections to an OLT's network interfaces (Network IF #1 and Network IF #2) via an ATM-PON interface. In (a), connections are banded. In (b), connections are disbanded due to congestion on IF #1. + +Figure 17/G.983.4 – Configuration of T-CONTs on the network interface + +##### 8.3.5.10.2 T-CONT types + +This clause presents definitions of T-CONTs, their types and typical applications for each T-CONT type. DBA-OLTs shall support all T-CONT types. ONUs/ONTs can support all or some of them according to the services they support. Basically, T-CONT types are independent of applications, such as ATC/QoS specified in the ATM layer. In short, one T-CONT type can accommodate any ATC/QoS, and can contain multiple different classes. However, typical applications in each type are mentioned to make use of maximal effectiveness of DBA. + +###### 8.3.5.10.2.1 Definition of T-CONT + +T-CONTs are essentially "pipes" that carry ATM VPs or VCs. Multiplexing of VPs and VCs having different ATC/QoS into one T-CONT is programmable. For example, the following scenarios can be assumed. + +- one or more VPs with the same ATC/QoS mapped into one T-CONT (e.g. VP switching case). +- one or more VPs with the different ATC/QoS mapped into one T-CONT (e.g. VP switching case). +- one or more VPs banding VCs with the same ATC/QoS mapped into one T-CONT (e.g. VC switching case). +- one or more VPs banding VCs with the different ATC/QoS mapped into one T-CONT (e.g. VC switching case) + +Note that one VP on the PON cannot be assigned to several T-CONTs in the current ATM-PON model specified in ITU-T Rec. G.983.1. + +For the sake of convenience, T-CONTs can be classified into 5 types, which are T-CONT Type 1, T-CONT Type 2, T-CONT Type 3, T-CONT Type 4, and T-CONT Type 5. + +Recommended supportability of ATC/QoS (or ATM Forum Service Category) in each T-CONT type is summarized in Table 4. + +**Table 4/G.983.4 – Relationship between ATC/QoS and T-CONT types** + +| ITU
ATC/QoS | ATM Forum
Service category | T-CONT types | | | | | +|---------------------------|-------------------------------|--------------|---|---|---|---| +| | | 1 | 2 | 3 | 4 | 5 | +| DBR [1] | CBR | X | | | | X | +| DBR [2] | VBR.1-nrt (SCR = PCR) | X | X | X | | X | +| DBR [U] | UBR.1 | X | X | X | X | X | +| SBR1 [1] | VBR.1-rt | X | | | | X | +| SBR1 [2] | VBR.1-nrt | X | X | X | | X | +| SBR1 [U] | UBR.1 | X | X | X | X | X | +| SBR2 [3] | VBR.2-nrt | X | X | X | | X | +| SBR2 [U] | UBR.1 | X | X | X | X | X | +| SBR3 [3] | VBR.3-nrt | X | X | X | | X | +| SBR3 [U] | UBR.2 | X | X | X | X | X | +| ABT/DT [1],
ABT/IT [1] | – | X | | | | X | +| ABT/DT [2],
ABT/IT [2] | – | X | X | X | | X | + +**Table 4/G.983.4 – Relationship between ATC/QoS and T-CONT types** + +| | | | | | | | +|---------------------------|-----|---|---|---|---|---| +| ABT/DT [U],
ABT/IT [U] | – | X | X | X | X | X | +| ABR [3] | ABR | X | X | X | | X | +| ABR [U] | ABR | X | X | X | X | X | +| GFR | GFR | X | X | X | | X | + +###### 8.3.5.10.2.2 Relationship among assigned bandwidth + +Each T-CONT type is characterized by the kinds of assigned bandwidth types it supports. Before a description of T-CONT types, the relationship among assigned bandwidth is clarified as follows. + +Assigned bandwidth consists of 4 types: Fixed bandwidth, Assured bandwidth, Non-assured bandwidth and Best-effort bandwidth (Maximum bandwidth can also be set in some cases). + +**Table 5/G.983.4 – Summary of assignable bandwidth** + +| | Delay sensitive | Assignment type | Applicable T-CONT types | | | | | +|-------------|-----------------|-----------------|-------------------------|--------|--------|--------|--------| +| | | | Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | +| Fixed | Yes | Provisioned | X | | | | X | +| Assured | No | Provisioned | | X | X | | X | +| Non-assured | No | Dynamic | | | X | | X | +| Best-effort | No | Dynamic | | | | X | X | + +NOTE – In Types 3, 4 and 5, assignable bandwidth has the upper bound specified by Maximum bandwidth that should be provisioned for these types. + +In the table, Dynamic Assignment type represents additional bandwidth. Non-assured bandwidth is paired with Assured bandwidth. Non-assured bandwidth for each T-CONT that requests additional bandwidth is allocated in proportion to the Assured bandwidth for the T-CONT from the pool of surplus bandwidth. If Assured bandwidth is zero, Non-assured bandwidth is fairly allocated as well as Best-effort bandwidth. For example, T-CONTs which request additional bandwidth and do not have Assured bandwidth fairly share surplus bandwidth. Moreover, Assured bandwidth assignment to any T-CONTs should be guaranteed. + +Assignable bandwidth can be prioritized as follows. + +| | | +|-------------------------------|-----------------------| +| Priority 1 (Highest priority) | Fixed bandwidth | +| Priority 2 | Assured bandwidth | +| Priority 3 | Non-assured bandwidth | +| Priority 4 (Lowest priority) | Best effort bandwidth | + +In the bandwidth assignment, Fixed bandwidth is reserved first, including slot location to minimize delay and delay variation. Assured bandwidth is reserved next using the remaining bandwidth. Bandwidth that is still not reserved is released to the pool of surplus bandwidth for Non-assured bandwidth and Best effort bandwidth. Non-assured bandwidth has higher priority than Best effort bandwidth. + +###### 8.3.5.10.2.3 T-CONT Type 1 + +###### 1) Definition + +T-CONT Type 1 is characterized by Fixed bandwidth only. For T-CONT Type 1, the bandwidth shall be exclusively and cyclically allocated with a fixed rate and controlled cell transfer delay. + +Traffic descriptor for T-CONT Type 1: Fixed bandwidth: Provisioned + +###### 2) *Applications* + +T-CONT Type 1 is able to accommodate any ATC/QoS. This T-CONT works in the same manner as the existing G.983.1 and G.983.2 Recommendations. Moreover, a Non-DBA-OLT is able to support any ATC/QoS as an application of T-CONT Type 1. DBA-OLTs accommodate real-time traffic as an application of this T-CONT type. DBA-OLTs always assign fixed bandwidth to connections on a T-CONT Type 1 regardless of whether there are cells to send or not. This T-CONT is not dynamically allocated and can be used to provide existing services (DS-1, E-1, J-1, etc). DBA-OLTs accommodate all of ATC/QoS classes in the ATM layer specified in ITU-T Recs. I.356 and I.371. + +Mechanisms to transfer cells in the T-CONT and provisioning policies to guarantee QoS on the ATM level depend on the implementation of the ONU/ONT. + +###### 3) *Behaviours of multiplexed VPCs and VCCs in the ATM layer* + +Multiple ATM connections are multiplexed into T-CONTs. Although configuration of T-CONT buffers depends on the implementation, Figure 18 illustrates an example of multiplexing DBR ATM connections using a typical implementation based on FIFO. As shown in Figure 18, though grants are allocated by a strict interval, CDV can be generated according to the behaviour of each ATM connection and/or contention among multiplexed connections. + +![Figure 18/G.983.4 – Behaviours of multiplexed connections on T-CONT type 1. The diagram shows three horizontal lines representing connection #1, connection #2, and connection #3. Connection #1 has a cell at the start. Connection #2 has a cell at the start. Connection #3 has a cell at the start. Below these, a box labeled 'Multiplexed connections on T-CONT' shows the cells being combined. A 'Delay' is indicated between the individual connections and the multiplexed stream. The multiplexed stream is labeled '1/PCR_connection #3'. A box labeled 'CDV=0' is shown on the multiplexed stream. The output of the multiplexed stream is labeled '1/PCR_connection #3' and shows a 'CDV' (Cell Delay Variation) between the cells. The bottom of the diagram shows a 'Fixed interval (= 1/Fixed Bandwidth of T-CONT)' with a double-headed arrow. The diagram is labeled 'T1546370-02'.](ff5f89b660edddb67971d7d3d4ce87ef_img.jpg) + +Figure 18/G.983.4 – Behaviours of multiplexed connections on T-CONT type 1. The diagram shows three horizontal lines representing connection #1, connection #2, and connection #3. Connection #1 has a cell at the start. Connection #2 has a cell at the start. Connection #3 has a cell at the start. Below these, a box labeled 'Multiplexed connections on T-CONT' shows the cells being combined. A 'Delay' is indicated between the individual connections and the multiplexed stream. The multiplexed stream is labeled '1/PCR\_connection #3'. A box labeled 'CDV=0' is shown on the multiplexed stream. The output of the multiplexed stream is labeled '1/PCR\_connection #3' and shows a 'CDV' (Cell Delay Variation) between the cells. The bottom of the diagram shows a 'Fixed interval (= 1/Fixed Bandwidth of T-CONT)' with a double-headed arrow. The diagram is labeled 'T1546370-02'. + +Figure 18/G.983.4 – Behaviours of multiplexed connections on T-CONT type 1 + +###### 8.3.5.10.2.4 T-CONT Type 2 + +###### 1) *Definition* + +T-CONT Type 2 is characterized by Assured bandwidth only. Assured bandwidth means Fixed average bandwidth over some specified time interval. In traffic engineering, this bandwidth is distinguished from Fixed bandwidth in T-CONT Type 1 (Deterministic assignment) which is controlled for the short-term range from a delay-sensitive point of view. In short, although T-CONT Type 1 guarantees cell transfer delay and delay variation + +in addition to the transmission rate, T-CONT Type 2 guarantees the average transmission rate only. T-CONT Type 2 is supported only by DBA-OLTs. + +Traffic descriptor for T-CONT Type 2: Assured bandwidth: Provisioned + +###### 2) *Application* + +T-CONT Type 2 accommodates all ATC/QoS classes with the exception of class 1, that is non-real time service. The ATC/QoS in the ATM layer shown in Table 4 can be accommodated in this T-CONT type. + +Mechanisms to transfer cells in the T-CONT and provisioning policies to guarantee QoS at the ATM level depend on the implementation of the ONU/ONT. + +###### 3) *Behaviours of multiplexed VPCs and VCCs in the ATM layer* + +Multiple ATM connections are multiplexed into T-CONTs. Although configuration of T-CONT buffers depends on the implementation, Figure 19 illustrates an example of multiplexing DBR ATM connections using a typical implementation based on FIFO. As shown in Figure 19, since grants are allocated by interval with a variation, CDV for each ATM connection can be generated by such variation in addition to the behaviour of each ATM connection and/or contention among multiplexed connections. + +![Figure 19/G.983.4 – Behaviours of multiplexed connections on T-CONT type 2. The diagram shows three connections (#1, #2, #3) being multiplexed onto a single T-CONT. Connection #3 is specifically labeled '1/PCR_connection #3'. The multiplexed connections are shown entering a 'Delay' block, which is associated with 'CDV=0'. The output of the delay block is labeled '1/PCR_connection #3' and is shown exiting the T-CONT. The output is then shown being delayed again, with 'CDV' indicated. The diagram includes vertical dashed lines representing time intervals, with a label 'Varied interval (mean = 1/Assured Bandwidth of T-CONT)' at the bottom. The text 'T1551070-02' is visible in the bottom right corner of the diagram area.](a93de4c3f80bd4a972ab65510b09b68d_img.jpg) + +Figure 19/G.983.4 – Behaviours of multiplexed connections on T-CONT type 2. The diagram shows three connections (#1, #2, #3) being multiplexed onto a single T-CONT. Connection #3 is specifically labeled '1/PCR\_connection #3'. The multiplexed connections are shown entering a 'Delay' block, which is associated with 'CDV=0'. The output of the delay block is labeled '1/PCR\_connection #3' and is shown exiting the T-CONT. The output is then shown being delayed again, with 'CDV' indicated. The diagram includes vertical dashed lines representing time intervals, with a label 'Varied interval (mean = 1/Assured Bandwidth of T-CONT)' at the bottom. The text 'T1551070-02' is visible in the bottom right corner of the diagram area. + +Figure 19/G.983.4 – Behaviours of multiplexed connections on T-CONT type 2 + +###### 8.3.5.10.2.5 T-CONT Type 3 + +###### 1) *Definition* + +T-CONT Type 3 has Assured bandwidth and Non-assured bandwidth. T-CONT Type 3 shall be allocated bandwidth equivalent to its Assured bandwidth, only when it has cells at a rate equivalent to Assured bandwidth or more than Assured bandwidth. Non-assured bandwidth shall be allocated across all T-CONTs with Assured bandwidth that are requesting additional bandwidth in proportion to the Assured bandwidth of the individual T-CONTs on the PON, e.g. Weighted Round Robin method. The sum of the Assured bandwidth and Non-assured bandwidth allocated to this T-CONT should not exceed its Maximum bandwidth, which is a provisioned value. + +Traffic descriptor for T-CONT Type 3: + +Assured bandwidth: Provisioned + +Non-assured bandwidth: Dynamic assignment + +Maximum bandwidth: Provisioned + +###### 2) *Application* + +T-CONT Type 3 accommodates variable bit rate transmission having QoS classes with the exception of class 1, that is non-real time service. ATC/QoS in the ATM layer described in Table 4 can be accommodated in this T-CONT type. + +Mechanisms to transfer cells in the T-CONT and provisioning policies to guarantee QoS on the ATM level depend on the implementation of the ONU/ONT. + +###### 3) *Behaviours of multiplexed VPCs and VCCs in the ATM layer* + +Multiple ATM connections are multiplexed into T-CONTs. Although the configuration of T-CONT buffers depends on the implementation, Figure 20 illustrates an example of bandwidth assignment based on the characteristics of T-CONT type 3. As shown in Figure 20, behaviours can be divided into four parts: Phases 1, 2, 3, and 4. In stable phases, such as Phases 1 and 3, these behaviours are the same as the case of T-CONT type 2. Multiplexing behaviours in transition phases, such as Phases 2 and 4, are illustrated in Figures 21 and 22, respectively, in the case of DBR connections. + +![Figure 20/G.983.4 – Outline of bandwidth assignment in T-CONT type 3](07c5a1c0fddd7da92a8427f5af840ffa_img.jpg) + +The diagram illustrates bandwidth assignment over time (t). The vertical axis represents bandwidth levels: 'Assured BW' and 'Non-assured BW'. The horizontal axis represents time, divided into four phases: + +- Phase 1: Bandwidth is at the 'Assured BW' level. +- Phase 2: Bandwidth increases to include 'Non-assured BW' on top of 'Assured BW'. +- Phase 3: Bandwidth remains at the combined 'Assured BW' and 'Non-assured BW' level. +- Phase 4: Bandwidth decreases back to the 'Assured BW' level. + +The label T1546390-02 is located at the bottom right of the graph. + +Figure 20/G.983.4 – Outline of bandwidth assignment in T-CONT type 3 + +Figure 20/G.983.4 – Outline of bandwidth assignment in T-CONT type 3 + +![Figure 21/G.983.4 – Behaviour of multiplexed connections in Phase 2 in T-CONT type 3](0713e654c91c38bdef6c70e14e82de23_img.jpg) + +This diagram shows the multiplexing of three connections onto a T-CONT during Phase 2. + +- Top section: 'Queued cells' for connection #1 (3 cells), connection #2 (1 cell), and connection #3 (2 cells) are shown on separate timelines. +- Middle section: Arrows show these cells being multiplexed onto a single 'Multiplexed connections on T-CONT' timeline. For connection #3, the interval between cells is marked as $1/\text{PCR\_connection \#3}$ and the Cell Delay Variation (CDV) is indicated. +- Bottom section: Two 'Varied interval' measurements are shown for the multiplexed stream: + - The first interval corresponds to 'Grant allocation according to assured BW', with $\text{mean} = 1/\text{Assured BW of T-CONT}$ . + - The second interval corresponds to 'Grant allocation according to assured BW + Non-assured BW', with $\text{mean} = 1/(\text{Assured BW} + \text{Non-assured BW of T-CONT})$ . +- A specific point on the timeline is marked with $\text{CDV}=0$ . + +The label T1546400-02 is at the bottom right. + +Figure 21/G.983.4 – Behaviour of multiplexed connections in Phase 2 in T-CONT type 3 + +Figure 21/G.983.4 – Behaviour of multiplexed connections in Phase 2 in T-CONT type 3 + +![Figure 22/G.983.4 – Behaviour of multiplexed connections in Phase 4 in T-CONT type 3. The diagram shows three connections (connection #1, #2, #3) with queued cells being multiplexed onto a T-CONT. Connection #1 has three cells, connection #2 has one, and connection #3 has two. These are multiplexed into a single T-CONT stream. The diagram illustrates the timing and bandwidth allocation for connection #3, showing a 1/PCR_connection #3 interval, CDV=0, and varied intervals for assured and non-assured bandwidth. The bottom part shows grant allocation according to assured BW + Non-assured BW and grant allocation according to assured BW. A label T1546410-02 is present.](38cbce07f83fba6d5a7c46605bd5743f_img.jpg) + +The diagram illustrates the multiplexing of three connections (connection #1, connection #2, and connection #3) into a single T-CONT. Connection #1 has three queued cells, connection #2 has one, and connection #3 has two. The multiplexed connections on the T-CONT are shown as a sequence of cells. For connection #3, the diagram highlights the 1/PCR\_connection #3 interval, which is marked as CDV=0. It also shows a varied interval (mean=1/Assured BW of T-CONT) and another varied interval (mean=1/(Assured BW + Non-assured BW of T-CONT)), both marked as CDV=0. The bottom part of the diagram shows two grant allocation periods: one for 'Grant allocation according to assured BW + Non-assured BW' and another for 'Grant allocation according to assured BW'. A label 'T1546410-02' is present in the bottom right. + +Figure 22/G.983.4 – Behaviour of multiplexed connections in Phase 4 in T-CONT type 3. The diagram shows three connections (connection #1, #2, #3) with queued cells being multiplexed onto a T-CONT. Connection #1 has three cells, connection #2 has one, and connection #3 has two. These are multiplexed into a single T-CONT stream. The diagram illustrates the timing and bandwidth allocation for connection #3, showing a 1/PCR\_connection #3 interval, CDV=0, and varied intervals for assured and non-assured bandwidth. The bottom part shows grant allocation according to assured BW + Non-assured BW and grant allocation according to assured BW. A label T1546410-02 is present. + +**Figure 22/G.983.4 – Behaviour of multiplexed connections in Phase 4 in T-CONT type 3** + +###### 8.3.5.10.2.6 T-CONT Type 4 + +###### 1) Definition + +T-CONT Type 4 has Best-effort bandwidth only and does not have any Guaranteed bandwidth. T-CONT Type 4 shall only use bandwidth that has not been allocated as Fixed bandwidth, Assured bandwidth or Non-assured bandwidth to T-CONTs in the PON. Best-effort bandwidth is allocated to each T-CONT Type 4 equally, e.g. based on the Round Robin method, up to the Maximum bandwidth. + +Traffic descriptor for T-CONT Type 4: + +Best-effort bandwidth: Dynamic assignment + +Maximum bandwidth: Provisioned + +###### 2) Application + +T-CONT Type 4 accommodates unspecified class as shown in Table 4. + +Mechanisms to transfer cells in the T-CONT and provisioning policies to guarantee QoS on the ATM level depend on the implementation of the ONU/ONT. + +###### 3) Behaviours of multiplexed VPCs and VCCs in the ATM layer + +Multiple ATM connections are multiplexed into T-CONTs. Although configuration of T-CONT buffers depends on the implementation, Figure 23 illustrates an example of bandwidth assignment based on the characteristics of T-CONT type 4. As shown in Figure 23, behaviours can be divided into four parts, such as Phases 1, 2, 3, and 4. In stable phases, such as Phases 1 and 3, these behaviours are the same as the cases of T-CONT types 2 and 3. Multiplexing behaviours in transition phases, such as Phases 2 and 4, are the same as the case of T-CONT type 3. + +![Figure 23/G.983.4 – Outline of bandwidth assignment in T-CONT type 4. The diagram shows a graph of bandwidth over time (t). The y-axis is labeled 'Best effort BW'. The graph is divided into four phases: Phase 1, Phase 2, Phase 3, and Phase 4. In Phase 1, the bandwidth is at a low level. In Phase 2, it increases to a higher level. In Phase 3, it decreases back to the low level. In Phase 4, it increases again to the higher level. The graph is labeled 'T1546420-02' at the bottom right.](657acccf744d33f1fc3a1652741a256e_img.jpg) + +Figure 23/G.983.4 – Outline of bandwidth assignment in T-CONT type 4. The diagram shows a graph of bandwidth over time (t). The y-axis is labeled 'Best effort BW'. The graph is divided into four phases: Phase 1, Phase 2, Phase 3, and Phase 4. In Phase 1, the bandwidth is at a low level. In Phase 2, it increases to a higher level. In Phase 3, it decreases back to the low level. In Phase 4, it increases again to the higher level. The graph is labeled 'T1546420-02' at the bottom right. + +**Figure 23/G.983.4 – Outline of bandwidth assignment in T-CONT type 4** + +###### 8.3.5.10.2.7 T-CONT Type 5 + +###### 1) *Definition* + +T-CONT Type 5 is the super set of all of T-CONT types. T-CONT Type 5 may accommodate any ATC/QoS described in Table 4, and can be downgraded to one or more of the other T-CONT types. T-CONT Type 5 is characterized by the following descriptors. + +Traffic descriptor for T-CONT Type 5: + +Fixed bandwidth: Provisioned + +Assured bandwidth: Provisioned + +Non-assured bandwidth: Dynamic assignment + +Best-effort bandwidth: Dynamic assignment + +Maximum bandwidth: Provisioned + +Assignment mechanisms depend on the implementation. For example, the following mechanisms can be assumed. + +*Step 1:* Fixed bandwidth and Assured bandwidth are assigned. + +*Step 2:* Non-assured bandwidth is assigned in proportion to Assured bandwidth. + +*Step 3:* If additional bandwidth is still requested, Best-effort bandwidth is assigned up to the Maximum bandwidth. + +###### 2) *Application* + +T-CONT type 5 can accommodate any application including real-time or resource-guaranteed applications. It can be applied to any ATC/QoS as shown in Table 4. + +Mechanisms to transfer cells in the T-CONT and provisioning policies to guarantee QoS on the ATM level depend on the implementation of the ONU/ONT. + +###### 3) *Behaviours of multiplexed VPCs and VCCs in the ATM layer* + +Multiple ATM connections are multiplexed into T-CONTs. Although configuration of T-CONT buffers depends on the implementation, Figure 24 illustrates an example of bandwidth assignment based on the characteristics of T-CONT type 5. As shown in Figure 24, behaviours can be divided into four parts: Phases 1, 2, 3, and 4. In stable Phases, such as Phases 1 and 3, these behaviours are shown in Figure 25. Multiplexing behaviours in transition phases, such as Phases 2 and 4, are the same as the cases of T-CONT type 3. + +![Figure 24/G.983.4 – Outline of bandwidth assignment in T-CONT type 5. The diagram shows a timeline 't' divided into four phases: Phase 1, Phase 2, Phase 3, and Phase 4. Two bandwidth levels are indicated: 'Non-assured BW + Best effort BW' and 'Fixed + Assured BW'. The 'Fixed + Assured BW' is a constant level across all phases. The 'Non-assured BW + Best effort BW' is zero in Phase 1, increases in Phase 2, and returns to zero in Phase 4. A label 'T1546430-02' is at the bottom right.](6ef03c6e28f2f1fd4f98529146ffeccc_img.jpg) + +Figure 24/G.983.4 – Outline of bandwidth assignment in T-CONT type 5. The diagram shows a timeline 't' divided into four phases: Phase 1, Phase 2, Phase 3, and Phase 4. Two bandwidth levels are indicated: 'Non-assured BW + Best effort BW' and 'Fixed + Assured BW'. The 'Fixed + Assured BW' is a constant level across all phases. The 'Non-assured BW + Best effort BW' is zero in Phase 1, increases in Phase 2, and returns to zero in Phase 4. A label 'T1546430-02' is at the bottom right. + +Figure 24/G.983.4 – Outline of bandwidth assignment in T-CONT type 5 + +![Figure 25/G.983.4 – Behaviour of multiplexed connections in Phases 1 and 3 in T-CONT type 5. The diagram shows three connections (connection #1, #2, #3) being multiplexed onto a T-CONT. Connection #3 is highlighted with a '1/PCR_connection #3' label. The diagram shows the 'Variable interval' (mean = 1/Assured BW) or (mean = 1/(Assured + Non-assured + Best effort BW)) and the 'Fixed interval (= 1/Fixed Bandwidth of T-CONT)'. The 'CDV=0' and 'CDV' labels indicate cell delay variation. A label 'T1546440-02' is at the bottom right.](7e2465b81aed11b2e58575a811424b75_img.jpg) + +Figure 25/G.983.4 – Behaviour of multiplexed connections in Phases 1 and 3 in T-CONT type 5. The diagram shows three connections (connection #1, #2, #3) being multiplexed onto a T-CONT. Connection #3 is highlighted with a '1/PCR\_connection #3' label. The diagram shows the 'Variable interval' (mean = 1/Assured BW) or (mean = 1/(Assured + Non-assured + Best effort BW)) and the 'Fixed interval (= 1/Fixed Bandwidth of T-CONT)'. The 'CDV=0' and 'CDV' labels indicate cell delay variation. A label 'T1546440-02' is at the bottom right. + +Figure 25/G.983.4 – Behaviour of multiplexed connections in Phases 1 and 3 in T-CONT type 5 + +###### 8.3.5.10.2.8 Notes for traffic behaviours + +When the PCR of a connection is smaller than the maximum bandwidth, implementing DBA may increase the CDV of the connection. Figure 26 shows a case of increasing CDV. In order to avoid cell discard by UPC, traffic descriptors for the T-CONT and the CDVT value for each connection should be considered carefully. + +![Figure 26/G.983.4 – CDV caused by DBA. The diagram shows two horizontal timelines: 'Actual arrival time' and 'Ideal arrival time'. On the 'Ideal arrival time' line, cells 'a', 'b', 'c', 'd', and 'e' are spaced at intervals of 1/PCR_VC. On the 'Actual arrival time' line, the same cells are shown, but their arrival times are shifted. A vertical dashed line marks a point where 'Bandwidth is changed'. Before this line, the interval between cells is 1/BWa. After the line, the intervals are 1/BWb. CDV (Cell Delay Variation) for each cell is indicated by horizontal double-headed arrows between the ideal and actual arrival times: 'CDV for cell 'b'', 'CDV for cell 'c'', 'CDV for cell 'd'', and 'CDV for cell 'e''. Cell 'a' is before the bandwidth change and has no CDV shown. The diagram is labeled T1546450-02.](dbd074feb5cce1300f42f91da8f673d1_img.jpg) + +Figure 26/G.983.4 – CDV caused by DBA. The diagram shows two horizontal timelines: 'Actual arrival time' and 'Ideal arrival time'. On the 'Ideal arrival time' line, cells 'a', 'b', 'c', 'd', and 'e' are spaced at intervals of 1/PCR\_VC. On the 'Actual arrival time' line, the same cells are shown, but their arrival times are shifted. A vertical dashed line marks a point where 'Bandwidth is changed'. Before this line, the interval between cells is 1/BWa. After the line, the intervals are 1/BWb. CDV (Cell Delay Variation) for each cell is indicated by horizontal double-headed arrows between the ideal and actual arrival times: 'CDV for cell 'b'', 'CDV for cell 'c'', 'CDV for cell 'd'', and 'CDV for cell 'e''. Cell 'a' is before the bandwidth change and has no CDV shown. The diagram is labeled T1546450-02. + +In case of " $BW\_min \leq BWa < PCR < BWb \leq BW\_max$ " + +**Figure 26/G.983.4 – CDV caused by DBA** + +##### 8.3.5.10.3 Additional requirements for surplus bandwidth assignment + +###### 8.3.5.10.3.1 Surplus bandwidth sharing and fairness on an ONU/ONT + +Surplus bandwidth in one ONU/ONT can be fairly shared with other DBA-T-CONTs in the same ONU/ONT and that can use surplus bandwidth (T-CONT type 3, T-CONT type 4 and T-CONT type 5). In short, one T-CONT working for T-CONT Types 3, 4 or 5 in one ONU/ONT can capture grants for surplus bandwidth which are then allocated to other T-CONTs in the ONU/ONT, if the other T-CONTs do not have transmission cells available. However, mechanisms to maintain a long-term balance of used grants among T-CONTs is for further study. + +##### 8.3.5.10.4 Requirements for grant allocation mechanisms + +This clause specifies the requirements for grant allocation mechanisms and their backgrounds. + +###### 8.3.5.10.4.1 Grant assignment for fixed bandwidth + +###### 1) Requirements + +This requirement is to restrict the fluctuation in the grant allocation interval to T-CONT Type 1 and the fixed bandwidth part of T-CONT Type 5 (this requirement is based on Peak-to-Peak CDV and maximum Cell Transfer Delay specified in ATM QoS parameters for Class 1). The maximum fluctuation of the interval between data grants in one T-CONT should take into account the following factors: + +- the time of the ranging window; +- the number of T-CONT Type 1 and T-CONT Type 5 in the same PON-IF; +- one cell time for one PLOAM cell or Divided\_slot; +- plus several cell times as margin. + +###### 2) Background + +These T-CONTs are used for DBR [Class 1] the same as the existing G.983.1 and G.983.2 Recommendations. Therefore, the limitation on burst allocation is the same as that of the system in the existing G.983.1 and G.983.2 Recommendations. In short, grant assignment for fixed bandwidth in a T-CONT can emulate the T-CONT as a physical link without + +contention among T-CONTs. Therefore, although it can be applied to all ATC/QoS; time sensitive applications, such as Class 1, are the most suitable. For example, in the case of T-CONT type 1 which uses only fixed bandwidth, when the sum of the PCRs of all ATM connections in this T-CONT are less than the fixed bandwidth assigned to this T-CONT and each connection has no CDV, maximum Cell Transfer Delay (CTD) and CDV can be specified logically as follows (see Figure 27). + +$$CTD < N * 1 / \text{Fixed bandwidth}$$ + +$$CDV < 1 / \text{PCR for the target connection} - 1 / \text{Fixed bandwidth}$$ + +where N is the number of multiplexing connections in one T-CONT. + +![Figure 27: CTD and CDV on T-CONT using only Fixed bandwidth. The diagram shows three connections (connection #1, #2, #3) entering a T-CONT. Connection #1 has a peak cell rate (PCR) of 1/PCR. The T-CONT has a fixed bandwidth of 1/Fixed bandwidth. The diagram illustrates the Cell Transfer Delay (CTD) and Cell Delay Variation (CDV) for connection #1. CTD is the time interval between the arrival of a cell at the T-CONT and its departure. CDV is the time interval between the departure of a cell and the next cell's departure. The diagram also shows the grant assignment interval and the T1546460-02 standard reference.](fb4274c4b7882a4059103f1dbca9b111_img.jpg) + +Figure 27: CTD and CDV on T-CONT using only Fixed bandwidth. The diagram shows three connections (connection #1, #2, #3) entering a T-CONT. Connection #1 has a peak cell rate (PCR) of 1/PCR. The T-CONT has a fixed bandwidth of 1/Fixed bandwidth. The diagram illustrates the Cell Transfer Delay (CTD) and Cell Delay Variation (CDV) for connection #1. CTD is the time interval between the arrival of a cell at the T-CONT and its departure. CDV is the time interval between the departure of a cell and the next cell's departure. The diagram also shows the grant assignment interval and the T1546460-02 standard reference. + +**Figure 27/G.983.4 – CTD and CDV on T-CONT using only Fixed bandwidth** + +###### 8.3.5.10.4.2 Grant assignment for other bandwidth + +###### 1) *Requirements* + +This requirement is to restrict the fluctuation in the grant allocation interval in every T-CONT to comply with the CDVT specified in each VPC or VCC at the UPC. + +###### 2) *Background* + +DBA should not cause cell loss by violating the CDVT at the UPC. Therefore, grant assignment should take this into account. There are two situations that may increase CDV. One is by burst grant assignment, and the other is by radical bandwidth update. + +The first case can be illustrated by the following examples. Figure 28 shows comparison of grant assignment methods. Figure 28 a) shows the case of grant assignment as Fixed bandwidth assignment. Figure 28 b) shows burst assignment. Figure 29 shows examples of performance in each grant assignment method. These examples show cases where the utilization rate in one T-CONT is 0.8. + +![Figure 28/G.983.4 – Comparison between grant assignment methods. Part (a) shows continuous grant assignment with six vertical bars. Part (b) shows burst grant assignment with a group of five bars followed by a long horizontal line with a double-headed arrow labeled 'N*the number of transmission frames'. The text 'T1546470-02' is at the bottom right.](4162c218fc7881cd90fc9574e07d2327_img.jpg) + +Figure 28/G.983.4 – Comparison between grant assignment methods. Part (a) shows continuous grant assignment with six vertical bars. Part (b) shows burst grant assignment with a group of five bars followed by a long horizontal line with a double-headed arrow labeled 'N\*the number of transmission frames'. The text 'T1546470-02' is at the bottom right. + +Figure 28/G.983.4 – Comparison between grant assignment methods + +![Figure 29/G.983.4 – Examples of performance in each grant assignment method. A line graph showing CDV [cells] on a logarithmic y-axis (1.00E+00 to 1.00E+03) versus The number of transmission frames (4 to 20). The 'Continuous grant assignment' line (blue diamonds) is flat at approximately 3 cells. The 'Burst grant assignment' line (pink squares) increases from about 150 cells at 4 frames to 1000 cells at 20 frames. The text 'T1546480-02' is at the bottom right.](b1601cda0f9b4fadfd55056c4f8ebce1_img.jpg) + +| The number of transmission frames | Continuous grant assignment [cells] | Burst grant assignment [cells] | +|-----------------------------------|-------------------------------------|--------------------------------| +| 4 | ~3 | ~150 | +| 8 | ~3 | ~300 | +| 12 | ~3 | ~500 | +| 16 | ~3 | ~800 | +| 20 | ~3 | ~1000 | + +Figure 29/G.983.4 – Examples of performance in each grant assignment method. A line graph showing CDV [cells] on a logarithmic y-axis (1.00E+00 to 1.00E+03) versus The number of transmission frames (4 to 20). The 'Continuous grant assignment' line (blue diamonds) is flat at approximately 3 cells. The 'Burst grant assignment' line (pink squares) increases from about 150 cells at 4 frames to 1000 cells at 20 frames. The text 'T1546480-02' is at the bottom right. + +Figure 29/G.983.4 – Examples of performance in each grant assignment method + +However, other methods to prevent the violation of CDVT, such as the new provisioning schemes for CDVT in the ATM-PON environment with DBA, may be required as future extensions. + +###### 8.3.5.10.4.3 Limitation of burst allocation for grant assignment + +###### 1) *Requirements* + +The burst allocation for grants to T-CONTs shall be limited to within a few milliseconds, if the DBA-T-CONTs have enough traffic to use those grants. + +###### 2) *Backgrounds* + +An excessively large burst allocation would result in discarded upstream cells by the UPC or would burden upstream shaping functions. Additionally, an excessively large burst allocation implies a long waiting time after the burst allocation. This causes large round trip times. TCP/IP Van-Jacobson slow start algorithm prevents very steep bandwidth ramp ups. The detailed criteria for the limitation of burst grant allocation and performance are under study. + +##### 8.3.5.10.5 Operations of grant assignment in combined environment + +Table 6 presents operations concerning grant assignment for possible combinations of these OLTs and ONUs/ONTs when DBA functions are activated. It shows the bandwidth allocation schemes that may be used for each specific combination. The DBA enhancement should inherit the G.983.1 downstream frame format. OLTs and ONUs/ONTs from different equipment manufacturers should be interoperable based on Table 6. + +**Table 6/G.983.4 – Operations of grant assignment** + +| | NSR-ONU/ONT | SR-ONU/ONT | NSR-ONU/ONT and SR-ONU/ONT | +|-------------|-------------|----------------------|--------------------------------------------------------------------------------------------| +| Non-DBA-OLT | (non-DBA) | (non-DBA) | (non-DBA) | +| DBA-OLT | NSR-DBA | SR-DBA
Or NSR-DBA | NSR-DBA for NSR-ONUs/ONTs and SR-DBA for SR-ONUs/ONTs
Or NSR-DBA for both ONU/ONT types | + +The operation of NSR-DBA and SR-DBA described in this table are detailed in 8.3.5.10.1.2 and 8.3.5.10.1.3, respectively. + +##### 8.3.5.10.6 Target performance + +This clause recommends some performance targets for the DBA protocol. The first two subclauses show performance targets that should be met regardless of input traffic or other variables. The remainder of this clause shows target performance for a standardized model for input traffic. + +###### 8.3.5.10.6.1 Waiting time + +###### 1) *Definition* + +This is the waiting time for dynamic bandwidth allocation to a T-CONT with Assured bandwidth (T-CONT Types 2, 3, and 5) since the T-CONT buffer in the ONU/ONT receives new cells under the condition that it has not been allocated grants (See Figure 30). + +![Figure 30/G.983.4 – Waiting time. A graph showing Bandwidth (BW) on the y-axis and time (t) on the x-axis. A horizontal dashed line represents the 'Assured bandwidth'. A vertical dashed line marks the point where 'The ONU/ONT receives new cells'. A horizontal double-headed arrow labeled 'Waiting time' spans from this vertical line to the start of a solid black horizontal line representing the granted bandwidth. The solid line starts at a higher bandwidth level than the assured bandwidth. The text 'T1546490-02' is in the bottom right corner.](468ad549a121ee06a5aa05e6915b7c39_img.jpg) + +Figure 30/G.983.4 – Waiting time. A graph showing Bandwidth (BW) on the y-axis and time (t) on the x-axis. A horizontal dashed line represents the 'Assured bandwidth'. A vertical dashed line marks the point where 'The ONU/ONT receives new cells'. A horizontal double-headed arrow labeled 'Waiting time' spans from this vertical line to the start of a solid black horizontal line representing the granted bandwidth. The solid line starts at a higher bandwidth level than the assured bandwidth. The text 'T1546490-02' is in the bottom right corner. + +**Figure 30/G.983.4 – Waiting time** + +###### 2) *Target performance* + +A few milliseconds shall be required (target of 2 ms). + +###### 3) *Background* + +Longer waiting time means that greedier traffic gets more bandwidth. The waiting time should be kept short so that users generating less traffic are still allocated sufficient bandwidth. This requirement is related to allocation delay (based on reporting cycle, transmission delay, updating cycle of bandwidth allocation and so on) after rest time. + +###### 8.3.5.10.6.2 Transition time + +###### 1) *Definition* + +The transition time is defined as the time from an ONU/ONT's status change to a state where the ONU/ONT is consistently allocated the proper bandwidth (See Figure 31). + +![Figure 31/G.983.4 – Transition time. A graph showing Bandwidth (BW) on the y-axis and time (t) on the x-axis. The graph shows a step-like increase in bandwidth. A horizontal dashed line represents the 'Proper bandwidth'. A solid line represents the bandwidth allocation. The line starts at a lower level, then at a point labeled 'ONU/ONT status change', it begins to rise linearly. It reaches the 'Proper bandwidth' level at a point labeled 'Transition time'. After this point, the line remains constant at the 'Proper bandwidth' level. The x-axis is labeled 't' and has a small code 'T1546500-02' at the bottom right.](1bc1bf231ada31f57cd9f0d8791b784b_img.jpg) + +Figure 31/G.983.4 – Transition time. A graph showing Bandwidth (BW) on the y-axis and time (t) on the x-axis. The graph shows a step-like increase in bandwidth. A horizontal dashed line represents the 'Proper bandwidth'. A solid line represents the bandwidth allocation. The line starts at a lower level, then at a point labeled 'ONU/ONT status change', it begins to rise linearly. It reaches the 'Proper bandwidth' level at a point labeled 'Transition time'. After this point, the line remains constant at the 'Proper bandwidth' level. The x-axis is labeled 't' and has a small code 'T1546500-02' at the bottom right. + +Figure 31/G.983.4 – Transition time + +###### 2) *Target performance* + +Ten milliseconds shall be required (target of 6 ms). + +###### 3) *Background* + +During transition time, bandwidth allocation is not fair. This requirement is related to the convergence time to achieve steady bandwidth allocation. + +### 8.3.6 ATM specific TC functions + +The specific information is described in ITU-T Rec. G.983.1. + +### 8.3.7 OAM functions + +The OAM functions that are installed in the ONU/ONT and OLT are shown in Figure 32. This figure also shows the notification signals between OLT and ONU/ONT. These signals are mapped into the message fields of the PLOAM cells. The general principles as defined in ITU-T Rec. I.610 can be applied to the PON. However, due to the point-to-multipoint nature of the physical medium, some notifications from OLT to ONU/ONT are obsolete principally due to the fact that the ONU/ONT is a slave to the OLT and the ONU/ONT is unable to do anything with these notifications. + +![Diagram of OAM functions between ONU/ONT and OLT. The ONU/ONT side lists various alarm signals: PEE, TF, BIP, REI, MEM, R_INH, ERR, SD, SUF, OAML, FRML, LCD, LOS, PEE, DIS, DACT, PST, and MIS. The OLT side lists corresponding alarm signals: PEEi, LOSi, LCDi, CPEi, OAMLi, SUFi, SDi, ERRi, REIi, LOAi, MEMi, R_INHi, BIP, DFi, TF, PEE, DACTi, MISi, and PST. Arrows indicate the flow of alarm notifications from the ONU/ONT to the OLT and from the OLT to external notification systems. A legend at the bottom left defines the symbols: ● Detection point, ○ Originating point, and ◉ Calculation and originating point. The diagram is labeled T1528310-98.](a2251e3bbfcd726b68cc50b091e53b02_img.jpg) + +● Detection point +○ Originating point +◉ Calculation and originating point + +T1528310-98 + +Diagram of OAM functions between ONU/ONT and OLT. The ONU/ONT side lists various alarm signals: PEE, TF, BIP, REI, MEM, R\_INH, ERR, SD, SUF, OAML, FRML, LCD, LOS, PEE, DIS, DACT, PST, and MIS. The OLT side lists corresponding alarm signals: PEEi, LOSi, LCDi, CPEi, OAMLi, SUFi, SDi, ERRi, REIi, LOAi, MEMi, R\_INHi, BIP, DFi, TF, PEE, DACTi, MISi, and PST. Arrows indicate the flow of alarm notifications from the ONU/ONT to the OLT and from the OLT to external notification systems. A legend at the bottom left defines the symbols: ● Detection point, ○ Originating point, and ◉ Calculation and originating point. The diagram is labeled T1528310-98. + +**Figure 32/G.983.4 – OAM functions** + +When multiple T-CONTs are specified in the ONU/ONT, alarms in each T-CONT are merged and represented as alarms for the ONU/ONT accommodating these T-CONTs. Moreover, the specific alarm for divided\_slots shall be defined to support SR-DBA. Figure 33 shows this alarm. This alarm is detected at the OLT and is described in 8.3.7.1. + +![Diagram showing OAM functions for divided_slot. It consists of two boxes labeled ONU/ONT and OLT. An arrow points from the OLT box to a signal labeled LOMSi, which is marked with a detection point symbol (●). The diagram is labeled T1546510-02.](2cf3896394a2342a2b46c504ab9a8830_img.jpg) + +T1546510-02 + +Diagram showing OAM functions for divided\_slot. It consists of two boxes labeled ONU/ONT and OLT. An arrow points from the OLT box to a signal labeled LOMSi, which is marked with a detection point symbol (●). The diagram is labeled T1546510-02. + +**Figure 33/G.983.4 – OAM functions for divided\_slot** + +#### 8.3.7.1 Items detected at OLT + +This clause describes the items detected at the OLT. The items are captured in Table 7 and are listed according to type. Detail is provided for the detection conditions and associated actions as well as the cancellation conditions and associated actions. + +Table 7/G.983.4 – Items detected at OLT + +| Type | Description | | +|----------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------| +| | Detection conditions | Actions | +| | Cancellation conditions | Actions | +| Transmitter failure | | | +| TF | The OLT transmitter is declared in failure when there is no nominal backfacet photocurrent or when the drive currents go beyond the maximum specification. | | +| Startup failure of ONUi/ONTi | | | +| SUFi | The ranging of ONU/ONTi has failed n times (n = 2; refer to 8.4.4.3.3) while the OLT has received optical bursts from this ONU/ONT. | Send three times deactivate_PON_ID messages. | +| | The ONU/ONT is reranged successfully. | | +| Physical equipment error of ONUi/ONTi | | | +| PEEi | When the OLT receives a PEE from the ONU/ONT. | Generate Loss_of_physical_layer_I notification. | +| | When the OLT does not receive a PEE message from the ONUi/ONTi in three seconds. | Stop Loss_of_physical_layer_I notification. | +| Loss of cell delineation of ONUi/ONTi | | | +| LCDi | When eight consecutive invalid delimiters or invalid HECs from ONUi/ONTi are received. | Send three times deactivate_PON_ID messages.
Generate Loss_of_physical_layer_I notification. | +| | When cell delineation for ONUi/ONTi is achieved in the operating state. | | +| PLOAM cell loss for ONUi/ONTi | | | +| OAMLi | When three consecutive PLOAM cells of ONUi/ONTi are missing. | Send three times deactivate_PON_ID messages.
Generate Loss_of_physical_layer_I notification. | +| | When the OLT receives a PLOAM cell corresponding to its PLOAM grant in the Operating state. | | +| Cell phase error for ONUi/ONTi | | | +| CPEi | When the OLT is able to receive the correct delimiter and the received cell phase is beyond the limits and the corrective actions of the OLT do not solve the problem. | Send three times deactivate_PON_ID messages.
Generate Loss_of_physical_layer_I notification. | +| | When the OLT receives a cell in the correct position in the operating state. | | + +**Table 7/G.983.4 – Items detected at OLT** + +| | Description | | +|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------| +| | Loss of signal of ONUi/ONTi | | +| LOSi | No valid optical signal at the O/E receiver received when expected for ONUi/ONTi during eight upstream sequential cells. | Send three times deactivate_PON_ID messages.
Generate Loss_of_physical_layer_I notification. | +| | When the OLT receives a valid optical signal corresponding to its grant in the Operating state. | | +| | Loss of acknowledge with ONUi/ONTi | | +| LOAi | The OLT does not receive an acknowledge from ONUi/ONTi after a set of downstream messages that imply an upstream acknowledge. | Send three times deactivate_PON_ID messages.
Generate Loss_of_physical_layer_I notification. | +| | When the OLT receives an acknowledge. | | +| | Deactivate failure of ONUi/ONTi | | +| DFi | The ONU/ONT does not react correctly after three DACT messages. | | +| | Cancelled by the operator. | | +| | Block error detection of ONUi/ONTi | | +| ERRi | The upstream received BIP8 is compared with the calculated BIP8 on the received stream. When there is a difference between them, the OLT issues ERRi. | | +| | ERRi should be renewed when the next upstream PLOAM cell is received at the OLT from ONUi/ONTi. | | +| | Signal degraded of ONUi/ONTi | | +| SDi | The number of differing bits is accumulated in Error_I during interval Tmeasure. The BER is defined as $BER = Error\_i / (BW * Tmeasure)$ where BW is the allocated upstream bandwidth.
When the upstream BER of ONUi/ONTi becomes $\geq 10^{-5}$ , this state is entered. | | +| | When the upstream BER of ONUi/ONTi becomes $< 10^{-5}$ , this state is cleared. | | +| | Remote error indication of ONUi/ONTi | | +| REIi | When the OLT receives a REI message it issues REIi. | | +| | ERRi should be renewed when the REI message is received at OLT from ONUi/ONTi. | | + +**Table 7/G.983.4 – Items detected at OLT** + +| | Description | | +|---------------|--------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------| +| MEMi | Message_error message from ONUi/ONTi | | +| | When the OLT receives an unknown message from ONUi/ONTi or received message_error message. | | +| | When the operator is informed. | | +| R-INHi | Receive alarm inhibition of ONUi/ONTi | | +| | When the OLT receives R-INH message from ONUi/ONTi, R-INHi is detected. | Ignore received alarms from this ONU/ONT.
Generate Loss_of_physical_layer_I notification. | +| | When the OLT receives a PLOAM cell in the ranging process of ONUi/ONTi. | | +| MISi | Link mismatch of ONUi/ONTi | | +| | The OLT detects that the received PSTi and the transmitted PST are different. | | +| | The OLT detects that received PSTi and the transmitted PST are the same. | | + +Table 8 lists the items detected at the OLT that are specific to divided slots. + +**Table 8/G.983.4 – Specific items for divided\_slots detected at OLT** + +| Type | Description | | +|--------------|--------------------------------------------------------------------------------------------------|----------------| +| | Detection conditions | Actions | +| | Cancellation conditions | Actions | +| LOMSi | Loss Of MiniSlot for ONUi/ONTi | | +| | When eight consecutive minislots of ONUi/ONTi are missing. | | +| | When the OLT receives a minislot corresponding to its divided slot grant in the operating state. | | + +NOTE – Detailed specifications of detection and cancellation conditions are defined as follows. + +Detection conditions: + +- When one or more of following conditions is detected, LOMSi is generated. +- No valid optical signal at the O/E receiver received for ONUi/ONTi when expected during eight upstream sequential mini-slots. +- When eight consecutive invalid delimiters of mini-slots from ONUi/ONTi are received. +- When the OLT can receive the correct delimiter and the received mini-slot cell phase is beyond the limits and the corrective actions of the OLT do not solve the problem. + +Cancellation conditions: + +- When all of following conditions are recognized, LOMSi is cancelled. + +- When the OLT receives a valid optical signal corresponding to its mini-slot grant in the DBA operating state. +- When mini-slot cell delineation for ONUi/ONTi is achieved in the operating state. +- When the OLT receives a mini-slot cell in the correct position in the operating state. + +#### **8.3.7.2 Items detected at ONU/ONT** + +The specific information is described in ITU-T Rec. G.983.1. + +### **8.3.8 Messages in the PLOAM channel** + +The specific information is described in ITU-T Rec. G.983.1. + +#### **8.3.8.1 Message definition** + +Message definitions for communication between the OLT and ONUs/ONTs are detailed in Table 9. + +**Table 9/G.983.4 – Message definition** + +| | Message Name | Function | Direction | Trigger | Number of times sent | Effect of receipt | +|---|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------|----------------------------------------------------------------------------|----------------------------------|---------------------------------------------------------------------------------------------------------------------------------------| +| 1 | No message | No message available when a PLOAM cell is transmitted. | OLT →
ONU/ONT | Empty message queue. | – | Discard. | +| 2 | New_churning_key_rq | Requests a new churning key from the ONU/ONT. | OLT →
ONU/ONT | OLT needs a new key for the churning mechanism. | 1 | ONU/ONT generates a new key and sends the key to the OLT with a new_churning_key message. | +| 3 | Upstream_RX_control | Instruct the ONU/ONT which pattern to fill in the RXCF part of the upstream PLOAM cell. | OLT →
ONU/ONT | Each time a ranging process is started. | 3 | The ONU/ONT sets the upstream RXCF field of the upstream PLOAM cell. | +| 4 | Upstream_overhead | Instruct the ONU/ONT which overhead and pre-assigned equalization delay to use in the upstream direction. | OLT →
ONU/ONT | Each time a ranging process is started. | 3 | The ONU/ONT sets the upstream overhead and the pre-assigned equalization delay. | +| 5 | Serial_number_mask | Provides a serial number and a mask masking a part of this serial number. | OLT →
ONU/ONT | To find the serial number of a unique ONU/ONT. | 1 | If serial number and mask match the ONU/ONT's serial number, the ONU/ONT is enabled to react on ranging grants. | +| 6 | Assign_PON_ID | Links a free PON_ID number with the serial number also provided in this message. | OLT →
ONU/ONT | When the OLT has found the serial number of a unique ONU/ONT. | 3 | The ONU/ONT with this serial number uses the returned PON_ID and will be addressed by this PON_ID. | +| 7 | Ranging_time | It indicates the value expressed in number of upstream bits that an ONU/ONT with the corresponding PON_ID must fill in into its equalization delay register. | OLT →
ONU/ONT | When the OLT decides that the delay must be updated, see ranging protocol. | 3 | The ONU/ONT fills in the equalization delay register with this value. | +| 8 | Deactivate_PON_ID | It instructs an ONU/ONT with this PON_ID to stop sending upstream traffic and reset itself. It can also be a broadcast message. | OLT →
ONU/ONT | When the LOSi, LCDi, OAMLi, LOAi, SUFi or CPEi are detected. | 3 | The ONU/ONT with this PON_ID switches off its laser and the PON_ID is discarded. It should be activated when the MPU is out of order. | +| 9 | Disable_serial_number | To disable an ONU/ONT with this serial number. | OLT →
ONU/ONT | On command from the OpS. | 3 or until no burst is detected. | Moves the ONU/ONT to the emergency stop state. The ONU/ONT cannot respond to grants. | + +**Table 9/G.983.4 – Message definition** + +| | | | | | | | +|----|------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 10 | Churning_key_update | To indicate to the ONU/ONT when the new churning key becomes valid.
Priority level is 1. | OLT → ONU/ONT | When the OLT is ready to churn data for ONU/ONT with PON_ID. | 3 | The ONU/ONT switches to the new churning key 48*Tframe after the first update message. Send one acknowledge after each correctly received message. | +| 11 | Grant_allocation message | To allocate a data and PLOAM grant to an ONU/ONT. | OLT → ONU/ONT | After a PON_ID is allocated to the ONU/ONT, it needs a data and PLOAM grant for sending the upstream data and PLOAM cells. | 3 | The ONU/ONT stores the two grant types. | +| 12 | Divided_slot_grant_configuration message | To allocate or deallocate a Divided_slot_grant to an ONU/ONT and identify the minislot length and offset position. | OLT → ONU/ONT | The OLT needs/no longer needs the service provided by the minislot. | 3 | The ONU/ONT sends the minislot after receiving this allocated divided_slot grant. If deallocated, it no longer reacts to this Divided_Slot_grant. | +| 13 | Configure_VP/VC | This message activates or deactivates a VP/VC in downstream and upstream for communication at the ATM layer. | OLT → ONU/ONT | When the OLT wants to set up or tear down a connection with the ONU/ONT, for example, for configuration of the UPC function, filling filtering tables or configuration of the interfaces of the ONU/ONT. | 3 | The ONU/ONT activates/deactivates these VP/VCs for the communication channel. Send one acknowledge after each correctly received message. | +| 14 | BER_interval | This defines the accumulation interval per ONU/ONT expressed in the number of downstream frames for the ONU/ONT counting the number of downstream bit errors. Same time-out as for Configure_VP/VC. | OLT → ONU/ONT | OpS defines this interval and can focus on one particular ONU/ONT. | 3 | The ONU/ONT starts a BER_interval timer and accumulates the downstream bit errors. Send one acknowledge after each correctly received message.

The sequence number in the REI messages is reset. | +| 15 | PST message | To check the OLT-ONU/ONT connectivity in a redundant configuration and perform APS. | OLT → ONU/ONT | Send it at a certain rate. | 1 time/second | ONU/ONT checks link number with own link number and generates a Link Mismatch MIS if different. | +| 16 | Physical_equipment_error message (PEE) | To indicate to the ONUs/ONTs that the OLT is unable to send both ATM cells and OMCC cells in the direction from ATM layer to TC layer. | OLT → ONU/ONT | When the OLT detects it cannot send both ATM cells and OMCC cells in the direction from ATM layer to TC layer. | 1 time/second | System specific. | + +**Table 9/G.983.4 – Message definition** + +| | | | | | | | +|----|--------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|-------------------------------------------------------------------------------|------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 17 | Churned_VP | To indicate to the ONUs/ONTs which VP/VC are churned or not. | OLT → ONU/ONT | When a new VP must be churned or not. | 3 | (Un)Mark this VP as churning. Send one acknowledge after each correctly received message. | +| 18 | Request_password message | Request the password from an ONU/ONT in order to verify it. The OLT has a local table of passwords for the connected ONUs/ONTs. If after a reranging, the password has changed, it will not activate this ONU/ONT. | OLT → ONU/ONT | After an ONU/ONT is ranged. This is optional. | 1 | Send the password message three times. | +| 19 | POPUP message | The OLT can request all connected ONUs/ONTs to restore their settings with the exception of the equalization delay and force the ONUs/ONTs to go from POPUP state to Operating standby state 3 (O7). | OLT → ONU/ONT | To speed up the reranging of a subset or all of the connected ONUs/ONTs. | 3 | The ONU/ONT restores the parameters it was using in operating state before it detected an LOS, LCD, OAML or FRML, with the exception of the equalization delay which is set to the pre-assigned equalization delay value. | +| 20 | Vendor_specific message | A number of Message_IDs are reserved for vendor specific messages. | OLT → ONU/ONT | Vendor specific. | Vendor specific. | Vendor specific. | +| 21 | No message | No message available when a PLOAM cell is transmitted. | OLT ← ONU/ONT | Empty message queue. | | Discard. | +| 22 | New_churning_key | Contains a new key to be used on the downstream churned cells to this ONU/ONT.
Priority level is 1. | OLT ← ONU/ONT | After the OLT request, the ONU/ONT fetches a new key and sends it to the OLT. | 3 times | The OLT initializes the churning engine with this new key if it receives three consecutive identical keys and switches to the new key 48*Tframe after the first churning_key_update message. | +| 23 | Acknowledge | This is used by the ONU/ONT to indicate the reception of a downstream Configure_VP/VC, Churning_key_update, Churned_VP, BER_interval message or Additional_Grant allocation message. Priority is 1 for the acknowledge on the churning_key_update message. The priority level is 0 for the others. The time-out for the acknowledge is 300 ms. | OLT ← ONU/ONT | After receiving every correct corresponding downstream message. | 1 time | The OLT is informed of good reception of the downstream message it was sending and performs the corresponding actions. | + +**Table 9/G.983.4 – Message definition** + +| | | | | | | | +|----|-------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------| +| 24 | Serial_number_ONU/ONT | This message contains the serial number of an ONU/ONT. | OLT ←
ONU/ONT | The ONU/ONT sends this message when in ranging mode and on receipt of a ranging grant or a PLOAM grant. | X (may be sent several times during the ranging protocol). | The OLT extracts the serial number and can assign a free PON_ID to this ONU/ONT. | +| 25 | Message_error message | This indicates that the ONU/ONT is unable to comply with a message from the OLT. | OLT ←
ONU/ONT | When the ONU/ONT is unable to comply with a message contained in a downstream PLOAM cell. | 3 | Inform the operator. | +| 26 | REI (Remote Error Indication) | This contains the number of downstream BIP mismatches (one count per bit mismatch) counted during the BER_interval. | OLT ←
ONU/ONT | When the BER_interval has expired. | 1 time/BER_interval | The OLT can show the average BER in function of time for an ONU/ONT. | +| 27 | R-INH | Used to inform the OLT that the ONU/ONT will power-off in a normal manner. This is to prevent the OLT from issuing unnecessary alarm reports. Priority level is 2. | OLT ←
ONU/ONT | The ONU/ONT generates this message when the power-off (such as the power switch off or the power cord extraction without battery backup) is activated in a normal operation. | At least 3 times | Discard any following alarms from this ONU/ONT.
Inform OpS. | +| 28 | PST message | To check the OLT-ONU/ONT connectivity in a redundant configuration and perform APS. | OLT ←
ONU/ONT | Send it at a certain rate. | 1 time/second | OLT checks link number with own link number and generates a Link Mismatch MISi if different. | +| 29 | Physical_equipment_error | To indicate to the OLT that the ONU/ONT is unable to send both ATM cells and OMCC cells in the direction from ATM layer to TC layer. | OLT ←
ONU/ONT | When the ONU/ONT detects it cannot send both ATM cells and OMCC Cells in the direction from ATM layer to TC layer. | 1 time/second | System specific | +| 30 | Password | Used to verify an ONU/ONT based on its password. | OLT ←
ONU/ONT | When the OLT requests the password by the request_password message. | 3 | If OLT receives three identical passwords, it is declared as valid. Further processing is system dependent. | +| 31 | Vendor_specific message | A number of Message_Ids are reserved for vendor specific messages. | OLT ←
ONU/ONT | Vendor specific. | Vendor specific | Vendor specific. | +| 32 | Additional_Grant_allocation message | To allocate 2nd or additional data grants to ONU/ONT. | OLT →
ONU/ONT | After a PON_ID is allocated to the ONU/ONT, it needs a data grant for sending the upstream data. | 3 | ONU/ONT has 2nd or additional data grant. Send one acknowledge after each correctly received message. | + +#### 8.3.8.2 Message formats + +This clause defines the contents of messages in the previous clause . + +##### 8.3.8.2.1 Downstream message formats + +This clause describes the downstream message formats. + +The following messages are described in ITU-T Rec. G.983.1: + +*No message* + +*Upstream\_Rx\_Control message* + +*Upstream\_overhead message* + +*Ranging\_time message* + +*Serial\_number\_mask message* + +*Assign\_PON\_ID message* + +*Deactivate\_PON\_ID message* + +*Disable\_serial\_number message* + +*New\_churning\_key\_request message* + +*Churning\_key\_update message* + +*Configure VP/VC message* + +*Physical\_equipment\_error message* + +*Request\_password message* + +*Churned\_VP message* + +*POPUP message* + +*Vendor\_specific message* + +*PST message* + +*BER\_interval message* + +Additional messages are used to accommodate DBA. Given the ONU/ONT's DBA parameters, the OLT can then configure the ONU/ONT to recognize additional data grants, send reports containing T-CONT buffer status via the divided slot channel, and reconfigure the reporting of T-CONTs without interruption of the reporting service. The three messages in the PLOAM channel that are used to perform this are the Grant\_allocation\_message, the Additional\_grant\_allocation message, and the Divided\_slot\_configuration message. The formats of these messages are given below. + +###### 1) *Grant\_allocation message* + +This message is applied to the first grant allocation. The format of this message is described in Table 10 and is the same as in ITU-T Rec. G.983.1. + +###### 2) *Additional\_grant\_allocation message* + +A new message called Additional\_grant\_allocation message is defined as follows to address the grant assignment to T-CONTs. The message id is 32. This message is used for the DBA system. The original Grant\_allocation message is only used initially during the ranging process. After that, the new Additional\_grant\_allocation message should be used to specify the divided slot grant, field offset, report type of this T-CONT, and grant. The format of this message is shown in Table 11. + +This message is sent to an ONU/ONT for each T-CONT inside the ONU/ONT. Each T-CONT is assigned a unique data grant. In other words, there is a one-to-one mapping between each data grant and each T-CONT. The T-CONT\_ID is used to provide an extra layer of abstraction between the grant number and the T-CONT buffer in the ONU/ONT. These must always exist in a one-to-one mapping between an active T-CONT\_ID and data grant. This abstraction allows for the grant number to be changed while maintaining the VP/VC configuration with the T-CONT\_ID, which is likely to occur in reranging or provisioned scenarios. + +###### 3) *Divided\_slot\_grant\_configuration message* + +Divided\_slot\_grant\_configuration message is unchanged from its definition in ITU-T Rec. G.983.1. For ease of reference, this message is shown in Table 12. + +**Table 10/G.983.4 – Grant\_allocation message** + +| Octet | Content | Description | +|--------|-----------|----------------------------------------------------------------------------------------------| +| 35 | PON_ID | Directed message to one ONU/ONT | +| 36 | 0000 1010 | Message identification "Grant_allocation" | +| 37 | dddd dddd | data grant allocated to the ONU/ONT with this PON_ID | +| 38 | 0000 000a | a:1 = Activate data grant for this ONU/ONT
a:0 = Deactivate data grant for this ONU/ONT | +| 39 | pppp pppp | PLOAM grant allocated to the ONU/ONT with this PON_ID | +| 40 | 0000 000a | a:1 = Activate PLOAM grant for this ONU/ONT
a:0 = Deactivate PLOAM grant for this ONU/ONT | +| 41..46 | 0000 0000 | Reserved | + +NOTE – Grant\_allocation message is used for first data grant and is the same in ITU-T Rec. G.983.1. + +**Table 11/G.983.4 – Additional\_grant\_allocation message** + +| Octet | content | Description | +|---------|------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 35 | PON_ID | Directed message to one ONU/ONT | +| 36 | 0010 0000 | Message identification for "Additional_grant_allocation" | +| 37 | dddd dddd | Data grant allocated to a T-CONT within the ONU/ONT with this PON_ID | +| 38 | 0000 000a | a: 1 – Activate data grant for this T-CONT
a: 0 – Deactivate data grant for this T-CONT | +| 39 | T-CONT_ID | The T-CONT_ID associated with this grant | +| 40 | DS_GR | Divided slot grant that this T-CONT will use to report status. 255 = no reporting for this T-CONT | +| 41 | RPT_type | Report type for this T-CONT
0 = default (1 byte, non-linear, total cells in buffer)
Other values are for future use, described in Appendix II | +| 42 | FLD_offset | field_offset for this T-CONT. Within the range [0, 52]. field_offset = 0 means T-CONT report starts right after the 3 bytes of overhead within the minislot. Offsets include any CRC fields contained within the minislot, hence an offset of 14, 29, 44, or 52 is always invalid here. | +| 43...46 | 0000 0000 | Reserved | + +**Table 12/G.983.4 – Divided\_Slot\_Grant\_configuration message** + +| Octet | Content | Description | +|--------|------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 35 | PON_ID | Directed message to one ONU/ONT | +| 36 | 0000 1011 | Message identification "Divided_slot_grant_configuration" | +| 37 | 0000 000a | a:1 = Activate grant for this ONU/ONT
a:0 = Deactivate grant for this ONU/ONT | +| 38 | DS_GR | Defines the grant value allocated to this ONU/ONT for sending a minislot. NOTE – the OLT can assign plural data grants. | +| 39 | LENGTH | Defines the length of the minislot payload in number of bytes. | +| 40 | OFFSET | Defines the offset of the start of the minislot in number of bytes from the start of an upstream cell slot.
OFFSET = 0 means minislot starts at the first byte of the upstream slot. | +| 41 | Service_ID | Defines the service to be mapped into the minislot.
0000 0000 is used for the MAC protocol.
Other values are for reserved for expansion. | +| 42..46 | 0000 0000 | Reserved | + +##### 8.3.8.2.2 Upstream message formats + +The specific information is described in ITU-T Rec. G.983.1. + +### 8.3.9 Automatic protection switching + +The specific information is described in ITU-T Rec. G.983.1. + +## 8.4 Ranging method + +### 8.4.1 Scope of the applied ranging method + +The specific information is described in ITU-T Rec. G.983.1. + +### 8.4.2 Features of ranging method for DBA + +Basically, the ranging method for DBA is the same as that in ITU-T Rec. G.983.1 to maintain backward compatibility with the existing ONU/ONT specified in ITU-T Rec. G.983.1. Moreover, the ONU/ONT should accept Additional\_grant\_allocation messages when in an operating state in order to be sent multiple data grants by the OLT. + +### 8.4.3 Phase relation specification between downstream and upstream + +The specific information is described in 8.4.2/G.983.1. + +### 8.4.4 Definition of messages used in the ranging protocol + +The specific information is described in 8.4.3/G.983.1. + +### 8.4.5 Ranging procedure + +#### 8.4.5.1 Overall ranging procedure + +The specific information is described in ITU-T Rec. G.983.1. + +#### 8.4.5.2 Ranging procedure in the ONU/ONT + +The specific information is described in ITU-T Rec. G.983.1. + +#### 8.4.5.3 States of the ONU/ONT + +The states and state transitions for the ONU/ONT are shown in Table 13. This table is similar to the state table found in Table 28/G.983.1 but includes an Additional\_Grant\_Allocation message. + +#### 8.4.5.4 Behaviour specification in the ONU/ONT + +The ability to support multiple T-CONTs is achieved by allocating a new grant in the Operating state when the PON\_ID matches its own PON\_ID. + +##### 8.4.5.4.1 Message reception + +The messages conveyed in the PLOAM cells from the OLT should be protected by the CRC, and the message receive-event should be generated when the CRC check is correct. In the case of a), c), d), and e) below, these messages are sent three times to ensure correct reception at the ONU/ONT. In these cases the message receive-event is generated after the message has been received correctly at least once. + +- a) *The receive-event of Upstream\_overhead message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- b) *The receive-event of Serial\_number\_mask message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- c) *The receive-event of Assign\_PON\_ID message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- d) *The receive-event of the Grant\_allocation message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- e) *The receive-event of Ranging\_time message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- f) *The receive-event of Deactivate\_PON\_ID message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- g) *The receive-event of Disable\_serial\_number message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- h) *The receive-event of POPUP message* + +The specific information is described in 8.4.4.2.2.1/G.983.1. + +- i) *The receive-event of the Additional\_grant\_allocation message* + +When the PON\_ID in the Additional\_Grant\_allocation message matches its own PON\_ID, an additional data grant is assigned and an acknowledgement is sent. + +##### 8.4.5.4.2 Grant reception + +The specific information is described in ITU-T Rec. G.983.1. + +##### 8.4.5.4.3 Other events + +The specific information is described in ITU-T Rec. G.983.1. + +**Table 13/G.983.4 – The state diagram of the ONU/ONT** + +| | Initial state
(O1) | Ranging standby state-1
(O2) | Ranging standby state-2
(O3) | Ranging standby state-3
(O4) | +|----------------------------------------|-------------------------------|-------------------------------------------------------------------|---------------------------------------------------|---------------------------------------------------| +| Upstream_overhead message | – | extract overhead
set pre-assigned
delay Te $\Rightarrow$ O3 | – | – | +| Optical power set-up complete | – | – | timer TO1 start
$\Rightarrow$ O5 | timer TO1 start
$\Rightarrow$ O5 | +| Serial_number_mask message | – | – | match SN(valid
bits)? $\Rightarrow$ O4 | unmatch
SN(valid bits)?
$\Rightarrow$ O3 | +| Assign_PON_ID message | – | – | – | – | +| Grant_allocation message | – | – | – | – | +| POPUP message | – | – | – | – | +| timer TO2 expire | – | – | – | – | +| timer TO1 expire | – | – | – | – | +| Ranging_time message | – | – | – | – | +| data grant | – | – | – | – | +| PLOAM grant | – | – | – | – | +| ranging grant | – | – | – | send PLOAM
cell | +| Deactivate_PON_ID message
(Note) | – | – | match PON_ID?
$\Rightarrow$ O2 | match PON_ID?
$\Rightarrow$ O2 | +| Disable_serial_number
message | – | Match SN and
enable = FFh?
$\Rightarrow$ O9 | match SN and
enable = FFh?
$\Rightarrow$ O9 | match SN and
enable = FFh?
$\Rightarrow$ O9 | +| detect LOS or LCD or OAML
or FRML | – | $\Rightarrow$ O1 | $\Rightarrow$ O1 | $\Rightarrow$ O1 | +| clear LOS and LCD and
OAML and FRML | $\Rightarrow$ O2 | – | – | – | +| Additional_grant_allocation
message | – | – | – | – | + +**Table 13/G.983.4 – The state diagram of the ONU/ONT** + +| | Operating standby state-1 (O5) | Operating standby state-2 (O6) | Operating standby state-3 (O7) | +|-------------------------------------|-----------------------------------------------------|-----------------------------------------------------|--------------------------------------------------------------------| +| Upstream_overhead message | – | – | – | +| Optical power set-up complete | – | – | – | +| Serial_number_mask message | match SN(valid bits)?
⇒ O6 | unmatch SN(valid bits)?
⇒ O5 | – | +| Assign_PON_ID message | match SN? → assign PON_ID | match SN? → assign PON_ID | – | +| Grant_allocation message | match PON_ID? → allocate data/PLOAM grant ⇒ O7 | match PON_ID? → allocate data/PLOAM grant ⇒ O7 | – | +| POPUP message | – | – | – | +| timer TO2 expire | – | – | – | +| timer TO1 expire | ⇒ O3 (alarm SUF) | ⇒ O3 ( alarm SUF) | ⇒ O3 ( alarm SUF) | +| Ranging_time message | – | – | match PON_ID?
→ timer TO1 stop
→ set equalization delay ⇒ O8 | +| data grant | – | – | – | +| PLOAM grant | – | – | send PLOAM cell | +| ranging grant | – | send PLOAM cell | – | +| Deactivate_PON_ID message (Note) | match PON_ID?
→ timer TO1 stop
⇒ O2 | match PON_ID?
→ timer TO1 stop
⇒ O2 | match PON_ID?
→ timer TO1 stop
⇒ O2 | +| Disable_serial_number message | match SN and enable = FFh? → timer TO1 stop
⇒ O9 | match SN and enable = FFh? → timer TO1 stop
⇒ O9 | match SN and enable = FFh? → timer TO1 stop
⇒ O9 | +| detect LOS or LCD or OAML or FRML | Timer TO1 stop
⇒ O1 | timer TO1 stop
⇒ O1 | timer TO1 stop
⇒ O1 | +| clear LOS and LCD and OAML and FRML | – | – | – | +| Additional_grant_allocation message | – | – | – | + +**Table 13/G.983.4 – The state diagram of the ONU/ONT** + +| | Operating
state
(O8) | Emergency stop
state-1
(O9) | POPUP
state
(O10) | +|-------------------------------------|-------------------------------------------------------------------------|-------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------| +| Upstream_overhead message | – | – | – | +| Optical power set-up complete | – | – | – | +| Serial_number_mask message | – | | | +| Assign_PON_ID message | – | – | – | +| Grant_allocation message | – | – | – | +| POPUP message | – | – | Restore laser settings, Upstream_overhead, LCF and RXCF fields, Te, PON_ID, and Grant allocation, timer TO1 start $\Rightarrow$ O7 | +| timer TO2 expire | – | – | $\Rightarrow$ O1 | +| timer TO1 expire | – | – | – | +| Ranging_time message | match PON_ID?
$\rightarrow$ update equalization delay | – | – | +| data grant | send ATM cell | – | – | +| PLOAM grant | send PLOAM cell | – | – | +| ranging grant | – | – | – | +| Deactivate_PON_ID message (Note) | match PON_ID? $\Rightarrow$ O2 | – | – | +| Disable_serial_number message | match SN and enable = FFh? $\Rightarrow$ O9 | match SN and enable = 00h? or enable = 0Fh and SN irrelevant $\Rightarrow$ O1 | – | +| detect LOS or LCD or OAML or FRML | Start timer TO2 $\Rightarrow$ O10 | – | $\Rightarrow$ O10 | +| clear LOS and LCD and OAML and FRML | – | – | – | +| Additional_grant_allocation message | match PON_ID?
$\rightarrow$ allocate data grant and send acknowledge | – | – | +| | | | | + +NOTE – Receive-event of a broadcast Deactivate\_PON\_ID message (the 35th octet of PON\_ID = 40h) is also assumed. +An ONU/ONT will leave the Operating state if a fault occurs or power is removed from the ONU/ONT. +Only maintenance signals of LOS, LCD, OAML, and FRML are considered in this state diagram. +"–" means no action for corresponding event. +PLOAM cell in the state of O4 should be transmitted in pre-assigned delay Te. +PON\_ID and Grant allocation should be cleared or discarded when the state transitions to O1, O2, O3, and O9 occur, and pre-assigned delay Te should be cleared in transitions to O1 and O2. + +##### 8.4.5.4.4 Ranging procedure in the OLT + +The specific information is described in ITU-T Rec. G.983.1. + +### 8.4.6 Ranging time requirements + +The specific information is described in 8.4.5/G.983.1. + +## 8.5 Handshake procedures + +### 8.5.1 Overall handshake procedure + +The typical model of class queues and T-CONTs in the ONU/ONT is shown in Figure 34. The procedures relating T-CONTs to grants are defined in this Recommendation; the procedures relating VP to class queues are defined in ITU-T Rec. G.983.2, and the procedures relating queues to T-CONTs are defined in ITU-T Rec. G.983.7. + +![Diagram of class queue and T-CONT mapping in an ONU/ONT.](f06d7a2fad72d80fe12fca1b65fc805b_img.jpg) + +The diagram illustrates the internal structure of an ONU/ONT. On the left, multiple input queues are shown. Arrows indicate the mapping of these queues to three T-CONTs (Traffic Containers) labeled ID=a, ID=b, and ID=c. This mapping is labeled 'Flexible mapping by the new OMCI'. Below the T-CONTs, a box labeled 'Identify H/W facilities of T-CONT' is shown, with an arrow pointing to it from the text 'Mapping by Additional\_grant\_allocation message'. To the right of each T-CONT, an arrow points outwards, labeled 'Grant code=x', 'Grant code=y', and 'Grant code=z' respectively. The entire diagram is enclosed in a box labeled 'ONU/ONT' at the top. A small code 'T1546520-02' is visible near the bottom right of the diagram. + +Diagram of class queue and T-CONT mapping in an ONU/ONT. + +Figure 34/G.983.4 – Typical model of class queue and T-CONTs in the ONU/ONT + +### 8.5.2 Negotiated parameters + +To configure the additional data grants and divided slot reporting, the OLT must learn the capabilities of the ONU/ONT in question. This information shall be obtained using the OMCI channel. The detailed procedures of the information exchange are described in ITU-T Rec. G.983.7. The key parameters for the TC layer functions described here are listed in Table 14. + +Table 14/G.983.4 – ONU/ONT parameters obtained via the DBA OMCI handshake + +| Parameter Name | Valid range | +|-------------------------------|-------------| +| Maximum_data_grants | 1..252 | +| Maximum_divided_slot_grants | 0..252 | +| T-CONT_buffer_reporting_types | 0..255 | + +The maximum\_data\_grants parameter can range from 1 (for an ONU/ONT with a single T-CONT) up to the theoretical maximum of 252 data grants (all the data grants on a PON with one ONU/ONT, although this is unlikely). + +The maximum\_divided\_slot\_grants parameter can range from 0 to 252. The minimum in this case (0) is for NSR-ONUs/ONTs. The cases of one or more divided\_slot\_grants are applied to SR-ONUs/ONTs. If operations of glitch-free reconfiguration specified in 8.6.2 are applied, two or more divided\_slot\_grants should be reserved. One of these divided\_slot\_grants cannot be used for real service, and should be used to step aside in transition of glitch-free operations according to 8.6.2. In SR-DBA, when glitch-free reconfiguration is not required, the case of one divided\_slot\_grant can be applicable. Moreover, if glitch-free operations that do not require one reserved divided\_slot\_grant besides operations in 8.6.2 are specified in the future, the case of one divided\_slot\_grants can be applicable even if glitch-free reconfiguration can be supported. The maximum is the same as for the data grants. + +The T-CONT-buffer\_reporting\_types is a special code that indicates the kinds of reports that this ONU/ONT can perform. Only one code (0) is defined as a normative default, and this signifies that the ONU/ONT shall report the total number of cells in the T-CONT buffer. Other codes are described in Appendix II. + +### 8.5.3 Detailed procedures + +Figure 35 shows the handshake sequence between the OLT and the ONU/ONT. + +#### Step 1 – Basic configuration of ONU/ONT + +This procedure is specified in UIT-T Rec. G.983.1. A grant is allocated in the ranging procedure, although the ONU/ONT is assumed to be NSR for the moment. + +#### Step 2 –The OLT gets the information about ONUs/ONTs + +This procedure is specified in UIT-T Rec. G.983.7. The OLT gets the following DBA support information from ONU/ONT: + +- The number of divided slot grants supported in this ONU/ONT. +- The number of T-CONTs supported in this ONU/ONT. +- The capability of T-CONT buffer reporting types for this ONU/ONT. + +#### Step 3 – Allocating a Divided-slot grant to the ONU/ONT + +If the ONU/ONT is able to report buffer status, the OLT sends "Divided\_Slot\_Grant\_configuration message" to the ONU/ONT. + +In this message the OLT specifies: + +- The minislot grant for this ONU/ONT. +- The minislot length for this ONU/ONT. +- The minislot offset for this ONU/ONT. + +#### Step 4 – Allocating a new data grant to the T-CONTs, or re-binding an existing data grant to a reporting field + +The OLT sends Additional\_grant\_allocation message to the ONU/ONT. In this message the OLT specifies: + +- The additional data grant for this ONU/ONT. +- The T-CONT ID associated with this data grant. + +- The minislot report type of this T-CONT. +- The divided slot grant for this T-CONT to use for reporting. +- The minislot field\_offset for this T-CONT within the minislot. + +After receiving this message, the ONU/ONT is able to associate the new or existing data grant to the appropriate minislot report field. + +If the ONU/ONT has multiple T-CONTs (grants), then the OLT needs to send this message multiple times, once per T-CONT. + +#### **Step 5 –Configuration of user VPs** + +This procedure is specified in ITU-T Recs. G.983.1, G.983.2 and G.983.7. The class queue is related to the T-CONT by the OMCI message. + +#### **Step 6 – Status reporting** + +This is the actual transmission of minislot reports in response to divided slot grants, as described in this Recommendation. + +![Sequence diagram showing the interaction between ONU/ONT and DBA-OLT. The diagram is divided into steps: STEP 1 G.983.1 (Initial handshake), STEP 2 G.983.7 (get_TC_information), STEP 3 G.983.1 (Divided_slot_grant_configuration), STEP 4 G.983.4 (Creation of T-CONT), STEP 5 G.983.1, G.983.2, and G.983.7 (VP Configuration), and STEP 6 G.983.4 (Divided slot grant).](8c3eb53c927f55acd19723cfcd0c43b6_img.jpg) + +``` + +sequenceDiagram + participant ONU as ONU/ONT + participant OLT as DBA-OLT + + Note over ONU, OLT: STEP 1 G.983.1 + OLT->>ONU: Upstream_overhead message + OLT->>ONU: Serial_number_mask message + OLT->>ONU: Ranging grant + ONU->>OLT: PLOAM cell + OLT->>ONU: Assign_PON_ID message + OLT->>ONU: Grant_allocation message + OLT->>ONU: PLOAM grant + ONU->>OLT: PLOAM cell + OLT->>ONU: Ranging_time message + Note left of ONU: "O8" + OLT->>ONU: Request_password message + ONU->>OLT: Password message + OLT->>ONU: Configure VP/VC message + ONU->>OLT: ACK + OLT->>ONU: BER_interval message (Optional) + ONU->>OLT: ACK + Note over ONU, OLT: (Wait/Loop symbol) + OLT->>ONU: Churning_key_update message (Optional) + ONU->>OLT: ACK + + Note over ONU, OLT: STEP 2 G.983.7 + OLT->>ONU: get_TC_information + Note over ONU, OLT: Negotiating the Minislot format (Optional) + + Note over ONU, OLT: STEP 3 G.983.1 + OLT->>ONU: Divided_slot_grant_configuration message + + Note over ONU, OLT: STEP 4 G.983.4 + OLT->>ONU: Additional_grant_allocation message + ONU->>OLT: ACK + + Note over ONU, OLT: STEP 5 G.983.1, G.983.2, and G.983.7 + rect rgb(255, 255, 255) + Note over ONU, OLT: VP Configuration + end + + Note over ONU, OLT: STEP 6 G.983.4 + OLT->>ONU: Divided slot grant + ONU->>OLT: Divided slot transmission + +``` + +The sequence diagram illustrates the interaction between the ONU/ONT and the DBA-OLT. The sequence is as follows: + +- STEP 1 G.983.1**: The DBA-OLT sends a series of messages to the ONU/ONT: Upstream\_overhead message, Serial\_number\_mask message, Ranging grant, PLOAM cell, Assign\_PON\_ID message, Grant\_allocation message, PLOAM grant, PLOAM cell, and Ranging\_time message. The ONU/ONT reaches state "O8". The DBA-OLT then sends Request\_password message, Password message, Configure VP/VC message, ACK, BER\_interval message (Optional), ACK, Churning\_key\_update message (Optional), and ACK. This entire sequence is labeled as "Initial handshake". +- STEP 2 G.983.7**: The OLT sends a get\_TC\_information message to the ONU/ONT. This is followed by an optional "Negotiating the Minislot format (Optional)" block. +- STEP 3 G.983.1**: The DBA-OLT sends a Divided\_slot\_grant\_configuration message to the ONU/ONT. +- STEP 4 G.983.4**: The DBA-OLT sends an Additional\_grant\_allocation message to the ONU/ONT, which responds with an ACK. This sequence is labeled as "Creation of T-CONT". +- STEP 5 G.983.1, G.983.2, and G.983.7**: A "VP Configuration" block is shown. +- STEP 6 G.983.4**: The DBA-OLT sends a Divided slot grant message to the ONU/ONT, which responds with a Divided slot transmission message. + +T1546530-02 + +Sequence diagram showing the interaction between ONU/ONT and DBA-OLT. The diagram is divided into steps: STEP 1 G.983.1 (Initial handshake), STEP 2 G.983.7 (get\_TC\_information), STEP 3 G.983.1 (Divided\_slot\_grant\_configuration), STEP 4 G.983.4 (Creation of T-CONT), STEP 5 G.983.1, G.983.2, and G.983.7 (VP Configuration), and STEP 6 G.983.4 (Divided slot grant). + +**Figure 35/G.983.4 – The sequence between the OLT and the ONU/ONT** + +## 8.6 Operations for creation and deletion of T-CONTs + +### 8.6.1 Requirements for operations of T-CONT status change + +T-CONTs on the ONU/ONT will be activated or deactivated according to user services in the operating status. In this situation the following requirements shall be met: + +#### a) *Partial activation of T-CONTs in a single SR-ONU/ONT* + +The OLT shall be able to activate individual T-CONTs in an SR-ONU/ONT as necessary. (R) + +The number and configuration of T-CONTs is expected to vary from SR-ONU/ONT to SR-ONU/ONT. The number of T-CONTs activated for any SR-ONU/ONT may not be the maximum number of T-CONTs that particular SR-ONU/ONT is capable of physically supporting. + +#### b) *The modification of the number of activated T-CONT in operating state (O8)* + +In operating state (O8), the number of activated T-CONTs inside an individual ONU/ONT shall be able to be modified according to changes of user configuration, operational situation, etc. (R) + +#### c) *Impact of addition or deletion of T-CONTs* + +Addition or deletion of individual T-CONTs shall not affect other T-CONTs serviced by an individual ONU/ONT. (R) + +Addition or deletion of individual T-CONTs or groups of T-CONTs shall not affect service to other T-CONTs served from an individual PON-IF board (or any other PON-IF board – this includes connections and ATM traffic). + +The change of set-up values of one T-CONT shall not affect the other T-CONTs serviced by the same ONU/ONT and serviced by the same PON-IF board, their connections, nor their ATM traffic. + +#### d) *Selection of T-CONT buffers* + +Any T-CONT buffer shall be individually selectable to support operational requirements. + +When a T-CONT number is mapped to a specific T-CONT buffer, the selection of the T-CONT number inside the ONU/ONT shall also be selected. + +### 8.6.2 Operations for creation of T-CONTs + +#### Reconfiguration of minislot reporting without impairments + +Configuration and reconfiguration of the minislot reporting system shall not cause any data errors or omissions in the underlying MAC information. There are two major parts of configuration: + +- Configuration of the divided slots, +- Configuration of the T-CONT reports within the minislots. + +The divided slots are configured using the Divided\_slot\_grant\_configuration message. The configuration of the divided slot has the properties that: + +- 1) multiple ONUs/ONTs can be affected by a change; +- 2) the timing recovery at the OLT must be coordinated with the configuration, and +- 3) the CRC checking must be coordinated with the configuration. For these reasons, it is not practical to modify a divided slot configuration. + +The only allowed operations are activate and deactivate. Specifically, for any divided slot grant/PON\_ID combination, it may be illegal to send consecutive activating Divided\_slot\_grant\_configuration messages with a different offset or size. + +For example, suppose an ONU/ONT has a divided slot configured that contains 4 report fields and then needs a fifth reporting field. It is not permissible to send a new configuration with a longer length, even if space exists in the divided slot. This is because the ONU/ONT will respond asynchronously to the new configuration, and the OLT will not know where to look for the trailing CRC. A similar problem occurs with changing the offset (start) of the minislot. The OLT will not know when to start looking for the start of the minislot. In either case, the OLT will not receive the information, and there will be a reporting impairment. + +Therefore, to achieve a resizing or relocation of a minislot retransmission, the procedure will be to first create a new minislot, transfer the reporting functionality to this new minislot, and then delete the old minislot. Since an ONU/ONT can only transmit one minislot per divided slot grant, this implies that the new minislot must exist in another divided slot. This is not as restrictive as it sounds, because to achieve optimal packing of the variable sized minislots into the divided slots it will be necessary to move all the minislots contained in one divided slot to a new divided slot. + +The configuration of the T-CONT reports within the minislots is mediated by the *Additional\_grant\_allocation* message. The fields in this message specify the current divided slot grant and offset to be used in reporting the T-CONT status. Note that this message can be sent in 3 cases: + +*Case 1:* This is a new grant allocation. + +*Case 2:* This is an existing grant deallocation. + +*Case 3:* This is an existing grant, being reconfigured to report in a different minislot. + +The first and second cases are clear, as they are the simple activate-deactivate pair, much like the use of the *Grant\_allocation* message in ITU-T Rec. G.983.1. The third case is used to reconfigure an existing T-CONT report to a new minislot, offset combination. Thus, the behaviour of the ONU/ONT upon receiving an *Additional\_grant\_allocation* message containing a grant number that was previously allocated is as follows: + +- Do not modify any of the traffic-affecting properties of the T-CONT. +- Change the minislot reporting association of that T-CONT to the newly specified one. +- Fill the now unused field in the old minislot with the idle code (0xFF). + +No particular timing relationship between the receipt of the message and the change is assumed. The OLT will be able to determine which of the two fields is active by looking for the idle code. Note that case 3 of the *Additional\_grant\_allocation* message can be applied to the grant that was provisioned using the *Grant\_allocation\_message* during the ranging procedure. In this way, that initial grant can be made into whatever type of T-CONT is needed for service. + +An illustration of the divided slot configuration and reconfiguration at creation of T-CONTs is given in Figure 36. The presumed sequence of this process is that the ONU/ONT is initially configured with 3 T-CONTs and then requires a fourth T-CONT. Note that in this sequence, steps 1-4 are the initial configuration, and steps 5-9 are the reconfiguration actions. The figure shows the contents of two minislots in divided slots No. 23 and No. 24 in the middle and right columns, respectively. + +NOTE – When the minislot is first created, the unused fields are filled with the idle code (0xFF). + +Note that between steps 1 and 9, the minislot with offset zero in divided\_slot No. 23 is well defined. Its beginning is at offset 0, and it has a total length of 7 bytes; therefore, its only CRC is found at offset = 6. This CRC is calculated by the ONU/ONT on whatever the minislot contains (idle codes or real reports). Hence, the OLT calculates the CRC on the received sequence, no matter what step the configuration process is in. The same applies to the other minislot contained in divided\_slot No. 24 from step 5 onward. This ensures that the lower layer processing at the OLT always has integrity. + +The approach being taken here is that the minislot transmission is exactly the right size for the number of T-CONTs being reported. This obviously requires a significant amount of messaging effort to maintain, and in many cases it will not reduce the bandwidth consumed by the minislots. A more efficient approach is to provision a modest but non-zero number of idle report fields for each ONU/ONT and utilize these as T-CONTs are provisioned and de-provisioned. + +Also note that the interchange in Figure 36 only concerns one ONU/ONT's transmissions. So, while ONU/ONT 1 moves its minislot from divided slot No. 23 to No. 24, another ONU/ONT could perhaps move its minislot from yet another divided slot to divided slot No. 23. In this case, divided slot No. 23 would not be unscheduled (following step 10). By moving ONUs/ONTs back and forth between a given set of divided slot grants, much reconfiguration can be achieved without actually adding new divided slots or removing old ones. However, there is a limit to the reconfigurations possible in this piecewise reconfiguration, as gaps between odd-size minislots are bound to form. This problem is addressed by the process of divided slot configuration, described below. + +![](c6212a3b14736d6a8c81ace75ae94ccf_img.jpg) + +Sequence diagram illustrating the creation procedure of T-CONTs and glitch-free minislot transmission for one ONU/ONT. + +**ONU/ONT 1** and **DBA-OLT** are the participants. + +**1st T-CONT is created.** + +Step 1. *Divided\_grant\_slot\_configuration* (PON\_ID=1, Activate DS\_grant=23, Offset=0, Length=7) + +Step 2. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=1, T-CONT ID=1, DS\_grant=23, Report Type=0, Offset=0) + +**Divided Slot #23** + +| | | | | | +|-------------|------|------|------|-----| +| PL Overhead | Idle | Idle | Idle | CRC | +|-------------|------|------|------|-----| + +**Divided Slot #23** + +| | | | | | +|-------------|-----------|------|------|-----| +| PL Overhead | R1 | Idle | Idle | CRC | +|-------------|-----------|------|------|-----| + +**2nd T-CONT is created.** + +Step 3. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=2, T-CONT ID=2, DS\_grant=23, Report Type=0, Offset=1) + +**Divided Slot #23** + +| | | | | | +|-------------|----|-----------|------|-----| +| PL Overhead | R1 | R2 | Idle | CRC | +|-------------|----|-----------|------|-----| + +**3rd T-CONT is created.** + +Step 4. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=3, T-CONT ID=3, DS\_grant=23, Report Type=0, Offset=2) + +**Divided Slot #23** + +| | | | | | +|-------------|----|----|-----------|-----| +| PL Overhead | R1 | R2 | R3 | CRC | +|-------------|----|----|-----------|-----| + +**4th T-CONT is created.** + +Step 5. *Divided\_slot\_grant\_configuration* (PON\_ID=1, Activate DS\_grant=24, Offset=0, Length=8) + +Step 6. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=1, T-CONT ID=1, DS\_grant=24, Report Type=0, Offset=0) + +Step 7. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=2, T-CONT ID=2, DS\_grant=24, Report Type=0, Offset=1) + +Step 8. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=1, T-CONT ID=3, DS\_grant=24, Report Type=0, Offset=2) + +Step 9. *Additional\_grant\_allocation* (PON\_ID=1, Activate grant=4, T-CONT ID=4, DS\_grant=24, Report Type=0, Offset=3) + +Step 10. *Divided\_slot\_grant\_configuration* (PON\_ID=1, Activate DS\_grant=23, Offset=n/a, Length=n/a) + +ONU/ONT 1 is now configured with 3 data grants, being reported in Divided\_slot #23. +A new service request requires one more data grant to be configured. + +**Divided Slot #23** + +| | | | | | +|-------------|----|----|----|-----| +| PL Overhead | R1 | R2 | R3 | CRC | +|-------------|----|----|----|-----| + +**Divided Slot #24** + +| | | | | | | +|-------------|------|------|------|------|-----| +| PL Overhead | Idle | Idle | Idle | Idle | CRC | +|-------------|------|------|------|------|-----| + +**Divided Slot #23** + +| | | | | | +|-------------|------|----|----|-----| +| PL Overhead | Idle | R2 | R3 | CRC | +|-------------|------|----|----|-----| + +**Divided Slot #24** + +| | | | | | | +|-------------|-----------|------|------|------|-----| +| PL Overhead | R1 | Idle | Idle | Idle | CRC | +|-------------|-----------|------|------|------|-----| + +**Divided Slot #23** + +| | | | | | +|-------------|------|------|----|-----| +| PL Overhead | Idle | Idle | R3 | CRC | +|-------------|------|------|----|-----| + +**Divided Slot #24** + +| | | | | | | +|-------------|----|-----------|------|------|-----| +| PL Overhead | R1 | R2 | Idle | Idle | CRC | +|-------------|----|-----------|------|------|-----| + +**Divided Slot #23** + +| | | | | | +|-------------|------|------|------|-----| +| PL Overhead | Idle | Idle | Idle | CRC | +|-------------|------|------|------|-----| + +**Divided Slot #24** + +| | | | | | | +|-------------|----|----|-----------|------|-----| +| PL Overhead | R1 | R2 | R3 | Idle | CRC | +|-------------|----|----|-----------|------|-----| + +**Divided Slot #23** + +| | | | | | +|-------------|------|------|------|-----| +| PL Overhead | Idle | Idle | Idle | CRC | +|-------------|------|------|------|-----| + +**Divided Slot #24** + +| | | | | | | +|-------------|----|----|----|-----------|-----| +| PL Overhead | R1 | R2 | R3 | R4 | CRC | +|-------------|----|----|----|-----------|-----| + +**Divided Slot #24** + +| | | | | | | +|-------------|----|----|----|----|-----| +| PL Overhead | R1 | R2 | R3 | R4 | CRC | +|-------------|----|----|----|----|-----| + +T1546540-02 + +Figure 36/G.983.4 - Creation procedure of T-CONTs and glitch-free minislot transmission for one ONU/ONT + +### 8.6.3 Operations for deletion of T-CONTs + +An illustration of the divided slot configuration and reconfiguration at deletion of a T-CONT is given in Figure 37. The presumed sequence of this process is that the ONU/ONT is initially configured with 4 T-CONTs and then no longer requires the 2nd and 4th T-CONTs. Note that in this sequence, steps 12-13 are the deletion actions, and steps 14-17 are the defragmentation action. The Figure shows the contents of two minislots in divided slots No. 23 and No. 24 in the middle and right columns, respectively. + +Note that between steps 12 and 16, the minislot with offset zero in divided\_slot No. 24 is well defined. Its beginning is at offset 0, and it has a total length of 8 bytes; therefore, its only CRC is found at offset = 7. This CRC is calculated by the ONU/ONT on whatever the minislot contains (idle codes or real reports). Hence, the OLT calculates the CRC on the received sequence, no matter what step the configuration process is in. This ensures that the lower layer processing at the OLT always has integrity. + +![](e404de9a69c05473fbd6af28ee32311b_img.jpg) + +ONU/ONT 1 + +DBA-OLT + +ONU/ONT 1 is now configured with 4 data grants, being reported in Divided\_slot #24. + +Divided Slot #24 + +| | | | | | | +|-------------|----|----|----|----|-----| +| PL Overhead | R1 | R2 | R3 | R4 | CRC | +|-------------|----|----|----|----|-----| + +2nd T-CONT is deleted. + +Step 12. Additional\_grant\_allocation +(PON\_ID=1, Activate grant=2, T-CONT ID=2, DS\_grant=24, Report Type=n/a, Offset=n/a) + +Divided Slot #24 + +| | | | | | | +|-------------|----|------|----|----|-----| +| PL Overhead | R1 | Idle | R3 | R4 | CRC | +|-------------|----|------|----|----|-----| + +ONU/ONT 1 is now reconfigured with three data grants being reported in Divided\_slot #24 +The unassigned field in the minislot can be left for future use or eventual consolidation. + +4th T-CONT is deleted. + +Step 13. Additional\_grant\_allocation +(PON\_ID=1, Activate grant=3, T-CONT ID=3, DS\_grant=24, Report Type=n/a, Offset=n/a) + +Divided Slot #24 + +| | | | | | | +|-------------|----|------|----|------|-----| +| PL Overhead | R1 | Idle | R3 | Idle | CRC | +|-------------|----|------|----|------|-----| + +ONU/ONT 1 is now reconfigured with three data grants being reported in Divided\_slot #24 +The unassigned field in the minislot can be left for future use or eventual consolidation. + +If defragmentation is expected. + +Step 14. Divided\_slot\_grant\_configuration +(PON\_ID=1, Activate DS\_grant=23, Offset=0, Length=6) + +Divided Slot #23 + +| | | | | +|-------------|------|------|-----| +| PL Overhead | Idle | Idle | CRC | +|-------------|------|------|-----| + +Step 15. Additional\_grant\_allocation +(PON\_ID=1, Activate grant=1, T-CONT ID=1, DS\_grant=23, Report Type=0, Offset=0) + +Divided Slot #23 + +| | | | | +|-------------|----|------|-----| +| PL Overhead | R1 | Idle | CRC | +|-------------|----|------|-----| + +Step 16. Additional\_grant\_allocation +(PON\_ID=1, Activate grant=3, T-CONT ID=2, DS\_grant=23, Report Type=0, Offset=1) + +Divided Slot #23 + +| | | | | +|-------------|----|----|-----| +| PL Overhead | R1 | R3 | CRC | +|-------------|----|----|-----| + +Divided Slot #24 + +| | | | | | | +|-------------|----|------|----|------|-----| +| PL Overhead | R1 | Idle | R3 | Idle | CRC | +|-------------|----|------|----|------|-----| + +Step 17. Divided\_slot\_grant\_configuration +(PON\_ID=1, Activate DS\_grant=24, Offset=n/a, Length=n/a) + +Divided Slot #23 + +| | | | | +|-------------|----|----|-----| +| PL Overhead | R1 | R3 | CRC | +|-------------|----|----|-----| + +Divided Slot #24 + +| | | | | | | +|-------------|------|------|------|------|-----| +| PL Overhead | Idle | Idle | Idle | Idle | CRC | +|-------------|------|------|------|------|-----| + +T1546550-0 + +Figure 37/G.983.4 – Creation procedure of T-CONTs and glitch-free minislot transmission for one ONU/ONT + +### 8.6.4 Impact by T-CONT status change + +As described in 8.6.2 and 8.6.3 and to avoid glitches, the OLT should reconfigure minislots without interruption of the reporting service. + +Figure 38 describes in general terms the process of divided slot consolidation, where several ONUs/ONTs' minislots are reconfigured in order to fit them into a small number of divided slots. + +Note that in the beginning case, two divided slots contain a number of poorly utilized and poorly spaced minislots. By a process of shifting each of these minislots into a more efficient version in a third minislot, all of the ONUs/ONTs can report in a single slot, and the two inefficient divided slots can be completely deconfigured and then taken out of the grant scheduler. + +![Diagram illustrating the reconfiguration of divided slots for multiple ONUs/ONTs. The diagram shows three levels of divided slots. Divided slot #1 contains minislots 1, 2, 3 for ONU/ONT1; 4, 5 for ONU/ONT2; and 6, 7 for ONU/ONT3. Divided slot #2 contains minislot E for ONU/ONT1; 8, 9, a for ONU/ONT4; N for ONU/ONT2; b for ONU/ONT5; U for ONU/ONT3; and c, d for ONU/ONT6. Divided slot #3 is a consolidated slot containing minislots 1, 2, 3 for ONU/ONT1; 8, 9, a for ONU/ONT4; 4, 5 for ONU/ONT2; b for ONU/ONT5; 6, 7 for ONU/ONT3; and c, d for ONU/ONT6. Arrows show the mapping of minislots from the first two slots into the third slot, with intermediate boxes (A, F, K, O, R, V) and grouped boxes (B,C,D, G,H,I, L,M, P, S,T, W,X) indicating the consolidation process. A small label T1546560-02 is present at the bottom right.](e5ded42f8e352da02ee86cb55550c45d_img.jpg) + +Diagram illustrating the reconfiguration of divided slots for multiple ONUs/ONTs. The diagram shows three levels of divided slots. Divided slot #1 contains minislots 1, 2, 3 for ONU/ONT1; 4, 5 for ONU/ONT2; and 6, 7 for ONU/ONT3. Divided slot #2 contains minislot E for ONU/ONT1; 8, 9, a for ONU/ONT4; N for ONU/ONT2; b for ONU/ONT5; U for ONU/ONT3; and c, d for ONU/ONT6. Divided slot #3 is a consolidated slot containing minislots 1, 2, 3 for ONU/ONT1; 8, 9, a for ONU/ONT4; 4, 5 for ONU/ONT2; b for ONU/ONT5; 6, 7 for ONU/ONT3; and c, d for ONU/ONT6. Arrows show the mapping of minislots from the first two slots into the third slot, with intermediate boxes (A, F, K, O, R, V) and grouped boxes (B,C,D, G,H,I, L,M, P, S,T, W,X) indicating the consolidation process. A small label T1546560-02 is present at the bottom right. + +Figure 38/G.983.4 – An illustration of a bandwidth conserving reconfiguration of divided slots + +List of the messages as indicated on the figure: + +Divided\_slot\_configuration PONID=1, Activate DS\_grant=3, Offset=0, Length=7 + +Additional\_grant\_allocation PONID=1, Activate grant=1, T-CONT\_ID=1, DS\_grant=3, Offset=0 + +Additional\_grant\_allocation PONID=1, Activate grant=2, T-CONT\_ID=2, DS\_grant=3, Offset=1 + +Additional\_grant\_allocation PONID=1, Activate grant=3, T-CONT\_ID=3, DS\_grant=3, Offset=2 + +Divided\_slot\_configuration PONID=1, Deactivate DS\_grant=1, Offset=n/a, Length=n/a + +Divided\_slot\_configuration PONID=4, Activate DS\_grant=3, Offset=7, Length=7 + +Additional\_grant\_allocation PONID=4, Activate grant=8, T-CONT\_ID=8, DS\_grant=3, Offset=0 + +Additional\_grant\_allocation PONID=4, Activate grant=9, T-CONT\_ID=9, DS\_grant=3, Offset=1 + +Additional\_grant\_allocation PONID=4, Activate grant=a, T-CONT\_ID=a, DS\_grant=3, Offset=2 + +Divided\_slot\_configuration PONID=4, Deactivate DS\_grant=2, Offset=n/a, Length=n/a + +Divided\_slot\_configuration PONID=2, Activate DS\_grant=3, Offset=14, Length=6 + +Additional\_grant\_allocation PONID=2, Activate grant=4, T-CONT\_ID=4, DS\_grant=3, Offset=0 +Additional\_grant\_allocation PONID=2, Activate grant=5, T-CONT\_ID=5, DS\_grant=3, Offset=1 +Divided\_slot\_configuration PONID=2, Deactivate DS\_grant=1, Offset=n/a, Length=n/a +Divided\_slot\_configuration PONID=5, Activate DS\_grant=3, Offset=20, Length=5 +Additional\_grant\_allocation PONID=5, Activate grant=b, T-CONT\_ID=b, DS\_grant=3, Offset=0 +Divided\_slot\_configuration PONID=5, Deactivate DS\_grant=2, Offset=n/a, Length=n/a +Divided\_slot\_configuration PONID=3, Activate DS\_grant=3, Offset=25, Length=6 +Additional\_grant\_allocation PONID=3, Activate grant=6, T-CONT\_ID=6, DS\_grant=3, Offset=0 +Additional\_grant\_allocation PONID=3, Activate grant=7, T-CONT\_ID=7, DS\_grant=3, Offset=1 +Divided\_slot\_configuration PONID=3, Deactivate DS\_grant=1, Offset=n/a, Length=n/a +Divided\_slot\_configuration PONID=6, Activate DS\_grant=3, Offset=31, Length=6 +Additional\_grant\_allocation PONID=6, Activate grant=c, T-CONT\_ID=c, DS\_grant=3, Offset=0 +Additional\_grant\_allocation PONID=6, Activate grant=d, T-CONT\_ID=d, DS\_grant=3, Offset=1 +Divided\_slot\_configuration PONID=6, Deactivate DS\_grant=2, Offset=n/a, Length=n/a +Remove Divided slot grants No. 1 and No. 2 from scheduler. + +Note that this kind of full defragmentation of the divided slots is the fullest expression of the reconfiguration process. As mentioned previously, it is also possible to add and subtract individual minislots on an ONU/ONT by ONU/ONT basis, especially if the implementation chooses to configure minislots of a fixed size, since doing so avoids having unusable spaces in the divided slots. + +#### **Frequency of divided slot consolidation** + +The purpose of divided slot consolidation is the conservation of bandwidth. However, unless the consolidation results in a net reduction of the total number of divided slot grants in use, it will not result in any saved bandwidth. Hence, before any reconfiguration is attempted, it should be determined if one (or more) divided slots can be fully eliminated. If not, then reconfiguration can be delayed. This prevents needless message activity on the PON. + +# **9 Operations Administration and Maintenance (OAM) functionality** + +The specific information is described in ITU-T Rec. G.983.1. + +# **10 Performance** + +Performance of the ATM level specified in ITU-T Rec. I.356 should be guaranteed for any ATC/QoS. However, detailed performance in the network with DBA should be discussed as a future issue. + +# **11 Environmental condition** + +The specific information is described in ITU-T Rec. G.983.1. + +# **12 Safety** + +The specific information is described in ITU-T Rec. G.983.1. + +# Appendix I + +## Algorithm for DBA + +This appendix presents some recommended algorithms for a DBA protocol, such as bandwidth assignment and grant allocation in the OLT. Currently, many algorithms have been evaluated. After completion of performance evaluation and comparison among these algorithms from several points of view, these algorithms are introduced in this appendix. + +DBA algorithms are classified into several parts as follows. + +## I.1 Algorithms for detecting ONU/ONT status for SR-ONU/ONT + +To detect congestion in the T-CONT, we can monitor the queue length at the ONU/ONT. Monitoring queue length means counting the number of waiting cells for transmission on the PON link. These processes are invoked in every T-CONT. + +### *Procedures* + +*Step 1:* The ONU/ONT monitors the queue length in every T-CONT buffer. + +*Step 2:* The ONU/ONT receives the divided slot grants from the OLT. + +*Step 3:* The ONU/ONT sends the total queue length information for every T-CONT. + +## I.2 Algorithms for monitoring cell streams at OLT from NSR-ONUs/ONTs + +We can detect congestion on the PON link by monitoring the number of receiving cells at the OLT. We present the procedures of this mechanism as one example. + +### *Procedures* + +*Step 1:* Monitor the number of received cells at the OLT in the fixed interval. + +*Step 2:* Calculate the utilization rate (= used BW/Current assigned BW) by using the results of real time monitoring in Step 1. + +*Step 3:* Recognize congestion by comparison between the utilization rate and thresholds. + +### *Notice* + +NOTE – In Step 1, we should study the definition of monitored cells, such as idle cell monitoring, user cell monitoring, or used cell monitoring. + +## I.3 Algorithms to update bandwidth + +When we calculate the updated bandwidth at the OLT, we can divide these mechanisms into three types, such as memory-less, stepwise increase, and stepwise increase and decrease. We can summarize these types as follows. + +### 1) *Memory-less* + +When we detect congestion in a T-CONT, we allocate more resources to this group independent of previously allocated resources. We present the outline of this mechanism as follows and illustrate operations in Figure I.1. + +![Diagram illustrating the operation in memory-less bandwidth update for three T-CONTs. Each T-CONT has a 'Max.' and 'Min.' bandwidth level. The diagram shows the allocation of bandwidth over time, with a 'Fixed interval to update BW' indicated by a double-headed arrow. T-CONT #1 has a pink bar between Min. and Max. levels. T-CONT #2 has a pink bar between Min. and Max. levels, with a blue line indicating a change. T-CONT #3 has a pink bar between Min. and Max. levels. The diagram is labeled T1546570-02.](caeb1637753f79f4cd005eda3768d1d5_img.jpg) + +Diagram illustrating the operation in memory-less bandwidth update for three T-CONTs. Each T-CONT has a 'Max.' and 'Min.' bandwidth level. The diagram shows the allocation of bandwidth over time, with a 'Fixed interval to update BW' indicated by a double-headed arrow. T-CONT #1 has a pink bar between Min. and Max. levels. T-CONT #2 has a pink bar between Min. and Max. levels, with a blue line indicating a change. T-CONT #3 has a pink bar between Min. and Max. levels. The diagram is labeled T1546570-02. + +**Figure I.1/G.983.4 – Operation in Memory-less bandwidth update** + +#### **Notations** + +Max: maximum bandwidth for one B-PON physical interface + +Max(i): maximum bandwidth for T-CONTi + +Min(i): minimum bandwidth for T-CONTi + +Old(i): allocated bandwidth for T-CONTi in the previous round + +New(i): updated bandwidth for T-CONTi + +SR(i): Shared bandwidth ratio for T-CONTi + +C(i): Congestion status at T-CONTi + +C(i)=1 if congestion for T-CONTi + +C(i)=0 if non congestion for T-CONTi + +Ad: Additional bandwidth for congested T-CONT + +#### **Procedures** + +If C(i) = 0 + +New(i) = Min(i) + +If C(i) = 1 + +New(i) = SR(i) \* (Max - sum(Min(j) : for any j)) + Min(i) + +If New(i) > Max(i) + +Ad = Ad + New(i) - Max(i) + +New(i) = Max(i) + +For example, in these procedures, SR(i) can be specified as follows1. + +$SR(i) = \frac{Min(i)}{\sum(C(j) * Min(j) : \text{for any } j)}$ + +1 As the similar method, we present SR(i) as follows. + +$SR(i) = \frac{(Max(i) - Min(i))}{\sum(C(j) * (Max(j) - Min(j)) : \text{for any } j)}$ + +Moreover, we should determine the procedure of how to share "Ad" to congested grant groups that can accept additional bandwidth after assignment of bandwidth. In short, we should specify the maximum number of retry calculations for each grant group until convergence of updated bandwidth. + +### 2) *Stepwise increase* + +When we detect congestion in a T-CONT, we increase resources stepwise to this group based on previously allocated resources. We present the sample pseudo codes using the above notations and illustrate operations in Figure I.2. + +![Figure I.2/G.983.4 – Operation in Stepwise increase bandwidth update. The diagram shows three horizontal bars representing T-CONT #1, T-CONT #2, and T-CONT #3. Each bar has a 'Max.' and 'Min.' level. T-CONT #1 shows a green bar at the 'Min.' level. T-CONT #2 shows a green bar at the 'Min.' level with a pink bar extending above it, and a blue arrow pointing to the pink bar. T-CONT #3 shows a green bar at the 'Min.' level with a pink bar extending above it, and a blue arrow pointing to the pink bar. A 'Fixed interval to update BW' is indicated by a double-headed arrow at the top. The text 'No decrease during congestion' is at the bottom.](b7b9fb0d8504e5e0dc06d2f930fc2444_img.jpg) + +Figure I.2/G.983.4 – Operation in Stepwise increase bandwidth update. The diagram shows three horizontal bars representing T-CONT #1, T-CONT #2, and T-CONT #3. Each bar has a 'Max.' and 'Min.' level. T-CONT #1 shows a green bar at the 'Min.' level. T-CONT #2 shows a green bar at the 'Min.' level with a pink bar extending above it, and a blue arrow pointing to the pink bar. T-CONT #3 shows a green bar at the 'Min.' level with a pink bar extending above it, and a blue arrow pointing to the pink bar. A 'Fixed interval to update BW' is indicated by a double-headed arrow at the top. The text 'No decrease during congestion' is at the bottom. + +Figure I.2/G.983.4 – Operation in Stepwise increase bandwidth update + +#### **Procedures(1)** + +``` + +If C(i) = 0 + New(i) = Min(i) +If C(i) = 1 + New(i) = SR(i) * [Max - sum{(1-C(j))*Min(j) : for any j}] + Old(i) + If New(i) > Max(i) + Ad = Ad + New(i) - Max(i) + New(i) = Max(i) + +``` + +For example, in these procedures, SR(i) can be specified as follows. + +$$SR(i) = Min(i) / \sum(C(j) * Min(j) : \text{for any } j)$$ + +Moreover, we can present another example of simplified procedures. + +#### **Procedures(2)** + +``` + +If C(i) = 0 + New(i) = Min(i) +If C(i) = 1 + New(i) = SR(i) * Old(i) + Old(i) + If New(i) > Max(i) + Ad = Ad + New(i) - Max(i) + New(i) = Max(i) + New(i) = min{New(i), New(i) / sum(New(j) : for any j) * Max} + +``` + +In this case, SR(i) can be a constant value, which is similar to the Rate Decrease Factor in ABR behaviour. + +### 3) *Stepwise increase and decrease* + +When we recognize update of congestion in a T-CONT, we increase and decrease resources stepwise to this group based on previously allocated resources and illustrate operations in Figure I.3. + +![Figure I.3/G.983.4 – Operation in Stepwise increase and decrease bandwidth update. The diagram shows three T-CONTs (T-CONT #1, #2, #3) over time. Each has a 'Max.' and 'Min.' bandwidth level. T-CONT #1 shows a decrease in bandwidth (orange arrow) after a congestion event (purple starburst). T-CONT #2 shows an increase in bandwidth (blue arrow) after a congestion event. T-CONT #3 shows a decrease in bandwidth (blue arrow) after a congestion event. A 'Fixed interval to update BW' is indicated by a double-headed arrow at the top. Below the diagram, the text 'No decrease during congestion' and 'No increase during non congestion' is underlined. The code 'T1546590-02' is visible at the bottom right of the diagram.](c41f93a5e921782a4d8e7705f52f74b5_img.jpg) + +Figure I.3/G.983.4 – Operation in Stepwise increase and decrease bandwidth update. The diagram shows three T-CONTs (T-CONT #1, #2, #3) over time. Each has a 'Max.' and 'Min.' bandwidth level. T-CONT #1 shows a decrease in bandwidth (orange arrow) after a congestion event (purple starburst). T-CONT #2 shows an increase in bandwidth (blue arrow) after a congestion event. T-CONT #3 shows a decrease in bandwidth (blue arrow) after a congestion event. A 'Fixed interval to update BW' is indicated by a double-headed arrow at the top. Below the diagram, the text 'No decrease during congestion' and 'No increase during non congestion' is underlined. The code 'T1546590-02' is visible at the bottom right of the diagram. + +**Figure I.3/G.983.4 – Operation in Stepwise increase and decrease bandwidth update** + +#### **Procedures** + +``` + +If C(i)=0 + New(i)=Old(i)-SR(i)*Old(i) + If New(i)Max(i) + Ad=Ad+New(i)-Max(i) + New(i)=Max(i) + New(i)=min{New(i), New(i)/sum(New(j): for any j)*Max} + +``` + +For example, in these procedures, SR(i) can be a constant value to simplify these procedures. It looks like the Rate Increase or Decrease Factor in ABR behaviour. + +## **I.4 Algorithms for grant assignment** + +Grants are assigned according to behaviours of each T-CONT type. + +## **I.5 Control allowing for Upstream Congestion of the OLT NNI** + +For Further Study. + +# Appendix II + +## Options for minislot format and negotiating procedures + +## II.1 Extended T-CONT reporting options + +It has been shown that to support T-CONTs that contain both CLP = 0 and CLP = 1 cells, it is necessary to report multiple cell counts to the OLT to ensure bandwidth fairness. Full reporting of each queue is impractical, as it would require excessive minislot fields. Therefore, a more compact notation is needed. This clause outlines the optional extended reporting options. + +### II.1.1 Report type field + +The reporting type appears in Octet 41 of the Additional\_grant\_allocation message. The defined values for this field are: + +Field = 0: Default: The report has one field, which contains the non-linear coding of the total number of cells in the T-CONT buffer. Each T-CONT buffer reporting uses 1 byte. Support of this type is mandatory. + +Field = 1: Two byte: The report has two fields, the first contains the non-linear coding of the total numbers of cells in T-CONT buffer that have PCR tokens (1 byte), and the second field contains the non-linear coding of the total number of cells in T-CONT buffer that have SCR tokens (1 byte). This type of reporting uses 2 bytes in total. This is suitable for T-CONT type 3 and type 5 reporting + +Field = 2: Four byte: The report has four fields. The first contains the non-linear coding of total number of T-CONT No. 2 class cells that have PCR tokens (assured BW) (1 byte). The second field contains the non-linear coding of the total number of T-CONT No. 3 class cells that have SCR tokens (assured BW) (1 byte). The third field contains the non-linear coding of the total number of T-CONT No. 3 class cells that have PCR tokens (non-assured BW) (1 byte). The fourth field contains the non-linear coding of the total number of T-CONT No. 4 class cells that have PCR tokens (best effort BW) (1 byte). This type of reporting uses 4 bytes in total. This is suitable for T-CONT type 5 reporting. + +Note that all reporting methods use the same non-linear coding for each subfield. + +### II.1.2 Reporting capability + +The reporting capability determined in the DBA OMCI handshaking exchange indicates the reporting capabilities of the ONU/ONT. The defined values of this capability code are: + +Code = 0: Default one byte reporting only is supported; + +Code = 1: One byte and two byte reporting supported; + +Code = 2: One byte and four byte reporting supported; + +Code = 3: One, two, and four byte reporting supported. + +Note that these codes basically specify a bit field that indicates support for the two optional reporting formats recommended in this appendix, allowing any combination of support. Note that all possible combinations include the normative one byte reporting method, ensuring interoperability over all ONU/ONT types. + +### II.1.3 Usage of extended reporting types + +The purpose of these extended reports is to give the OLT more information on the types of traffic waiting in the T-CONT buffer. Because the T-CONT buffer can contain multiple connections of multiple ATM service classes, a single cell count does not always give sufficient information on the traffic state of the T-CONT. + +An example of the implementation of a T-CONT buffer that supports two-byte reporting is shown in Figure II.1. This shows a buffer that implements a weighted round robin type of scheduler, and each queue is policed using the standard dual-leaky bucket generic cell rate algorithm (GCRA). The derivation of the two cell counts to be sent in the two-byte report is shown to be the sum over all queues of the cells that have SCR tokens and PCR tokens, respectively. With these counts, the OLT DBA algorithm can send grants to those T-CONTs that have more SCR tokens first, ensuring fairness. + +A similar process would be done to compute the four counts required for the four-byte reporting method, with the sums being taken over the groups of connections as listed for that mode. + +![Block diagram of a WRR dual-leaky bucket regulated scheduler. The diagram shows a 'WRR Control Logic' block receiving a 'Grant Arrival' and outputting a 'Selected Address To Queue Server'. It interacts with a 'WRR \'Wheel\' Table' (outputting signal i) and an 'Address Decoder' (receiving signal j). The Address Decoder controls multiple queue stages (1 to n). Each stage includes a 'Cells in Queue' buffer fed by an 'AAL' from a 'Line Interface'. Each stage has two leaky bucket mechanisms: one for PCR (Peak Cell Rate) and one for SCR (Sustainable Cell Rate). Each mechanism consists of a timer, a token counter, and a 'min' block. The 'min' blocks output signals p_1, s_1 through p_n, s_n back to the control logic and address decoder. Summation blocks (Σ) at the bottom calculate 'Total SCR tokened cells' and 'Total PCR tokened cells'. An 'or' gate at the top combines signals from the control logic and address decoder.](d1ad05f1189b0d80188fee24ae33c112_img.jpg) + +The diagram illustrates the architecture of a WRR dual-leaky bucket regulated scheduler. On the left, a 'Grant Arrival' signal enters the 'WRR Control Logic' block. This block also outputs a 'Selected Address To Queue Server' signal and provides signals $p_j$ and $s_j$ to the 'Address Decoder'. The 'WRR Control Logic' is connected to a 'WRR \'Wheel\' Table' which outputs a signal $i$ . The 'Address Decoder' receives inputs from the 'WRR Control Logic' and the 'WRR \'Wheel\' Table' (signal $j$ ). Above the 'Address Decoder' is an 'or' gate. Below the 'Address Decoder' are two summation blocks, $\Sigma$ , which output 'Total SCR tokened cells' and 'Total PCR tokened cells'. The 'Address Decoder' outputs are connected to multiple queues, labeled 1 to $n$ . Each queue consists of a 'Cells in Queue' block, a 'min' block for PCR tokens, and a 'min' block for SCR tokens. The 'Cells in Queue' block is connected to an 'AAL' block labeled 'From Line Interface'. The 'min' blocks are connected to 'PCR tokens' and 'SCR tokens' blocks, which are in turn connected to 'PCR timer' and 'SCR timer' blocks. The 'min' blocks also output signals $p_1, s_1, \dots, p_n, s_n$ . The 'WRR Control Logic' block also outputs a signal 'To Queue Server'. + +Block diagram of a WRR dual-leaky bucket regulated scheduler. The diagram shows a 'WRR Control Logic' block receiving a 'Grant Arrival' and outputting a 'Selected Address To Queue Server'. It interacts with a 'WRR \'Wheel\' Table' (outputting signal i) and an 'Address Decoder' (receiving signal j). The Address Decoder controls multiple queue stages (1 to n). Each stage includes a 'Cells in Queue' buffer fed by an 'AAL' from a 'Line Interface'. Each stage has two leaky bucket mechanisms: one for PCR (Peak Cell Rate) and one for SCR (Sustainable Cell Rate). Each mechanism consists of a timer, a token counter, and a 'min' block. The 'min' blocks output signals p\_1, s\_1 through p\_n, s\_n back to the control logic and address decoder. Summation blocks (Σ) at the bottom calculate 'Total SCR tokened cells' and 'Total PCR tokened cells'. An 'or' gate at the top combines signals from the control logic and address decoder. + +**Figure II.1/G.983.4 – An implementation of a WRR dual-leaky bucket regulated scheduler** + +Note that the control logic is triggered by the arrival of a grant and then selects the next queue to be served based on: the weights configured in the 'wheel table', the availability of SCR and PCR tokens, and the presence of SCR tokenized cells in any queue. Also note that the occupancy of the multiple queues is summarized by calculating the total SCR and PCR tokenized cells. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.984.5-202202-I_PDF-E/raw.md b/marked/G/T-REC-G.984.5-202202-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..25bf36045188ef13f89f40793f7a6b15e625649a --- /dev/null +++ b/marked/G/T-REC-G.984.5-202202-I_PDF-E/raw.md @@ -0,0 +1,549 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.984.5** + +(02/2022) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical line +systems for local and access networks + +--- + +**Gigabit-capable passive optical networks +(G-PON): Enhancement band** + +Recommendation ITU-T G.984.5 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.984.5 + +## Gigabit-capable passive optical networks (G-PON): Enhancement band + +## Summary + +Recommendation ITU-T G.984.5 defines wavelength ranges reserved for additional service signals to be overlaid via wavelength division multiplexing (WDM) in gigabit-capable passive optical networks (G-PONs) for maximizing the value of optical distribution networks (ODNs). + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.984.5 | 2007-09-22 | 15 | 11.1002/1000/9185 | +| 1.1 | ITU-T G.984.5 (2007) Amd.1 | 2009-10-09 | 15 | 11.1002/1000/10543 | +| 2.0 | ITU-T G.984.5 | 2014-05-14 | 15 | 11.1002/1000/12184 | +| 2.1 | ITU-T G.984.5 (2014) Amd. 1 | 2018-05-07 | 15 | 11.1002/1000/13527 | +| 2.2 | ITU-T G.984.5 (2014) Amd. 2 | 2020-10-29 | 15 | 11.1002/1000/14490 | +| 3.0 | ITU-T G.984.5 | 2022-02-13 | 15 | 11.1002/1000/14927 | + +## Keywords + +Coexistence element, enhancement band, G-PON, wavelength blocking filter, WDM filter. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2022 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|--------------------------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation..... | 2 | +| 4 Abbreviations and acronyms ..... | 3 | +| 5 Conventions ..... | 4 | +| 6 Reference architecture ..... | 4 | +| 7 Operating wavelength..... | 6 | +| 8 X/S tolerance of G-PON ONU ..... | 8 | +| Appendix I – Example of WDM1, WDM1r, CEx and CEMx characteristics..... | 10 | +| Appendix II – Examples of wavelength allocation for NGA services and video distribution services ..... | 11 | +| II.1 Introduction ..... | 11 | +| II.2 Case 1: Integrated filter for video..... | 11 | +| II.3 Case 2: Discrete WDM filter for video ..... | 13 | +| Bibliography..... | 15 | + + + +## Recommendation ITU-T G.984.5 + +## Gigabit-capable passive optical networks (G-PON): Enhancement band + +## 1 Scope + +The purpose of this Recommendation is to define wavelength ranges reserved for additional service signals to be overlaid via wavelength division multiplexing (WDM) in gigabit-capable passive optical networks (G-PONs) for maximizing the value of optical distribution networks (ODNs). + +For this purpose, this Recommendation defines and provides: + +- wavelength ranges to be reserved; and +- X/S tolerance in PON optical network units (ONUs). + +Appendices I and II provide: + +- a general reference diagram of coexistence elements, and sample parameters of a discrete WDM filter that combines and isolates up/down signals of passive optical network (PON) systems, radio frequency (RF) signals and optical time-domain reflectometer (OTDR) signals at the optical line termination (OLT) side; +- examples of wavelength allocation for next generation access (NGA) services and video distribution services. + +The physical media dependent (PMD) layer specification for G-PON in the absence of an enhancement band is defined in [ITU-T G.984.2]. PMD layer specifications for G-PON in the presence of enhancement bands are defined by the combination of [ITU-T G.984.2] and this Recommendation. Whenever a parameter specified in [ITU-T G.984.2] is not explicitly mentioned in this Recommendation, its value given in [ITU-T G.984.2] remains valid. Whenever a parameter is specified in both this Recommendation and [ITU-T G.984.2], the specification in this Recommendation takes precedence. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*. +- [ITU-T G.671] Recommendation ITU-T G.671 (2019), *Transmission characteristics of optical components and subsystems*. +- [ITU-T G.983.1] Recommendation ITU-T G.983.1 (2005), *Broadband optical access systems based on Passive Optical Networks (PON)*. +- [ITU-T G.983.3] Recommendation ITU-T G.983.3 (2001), *A broadband optical access system with increased service capability by wavelength allocation*. +- [ITU-T G.984.2] Recommendation ITU-T G.984.2 (2019), *Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification*. + +| | | +|------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T G.987] | Recommendation ITU-T G.987 (2012), 10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations and acronyms. | +| [ITU-T G.987.2] | Recommendation ITU-T G.987.2 (2016), 10-Gigabit-capable passive optical networks (XG-PON): Physical media dependent (PMD) layer specification. | +| [ITU-T G.989] | Recommendation ITU-T G.989 (2014), 40-Gigabit-capable passive optical network (NG-PON2) systems: Definitions, abbreviations and acronyms. | +| [ITU-T G.989.1] | Recommendation ITU-T G.989.1 (2013), 40-Gigabit-capable passive optical networks (NG-PON2): General requirements. | +| [ITU-T G.9805] | Recommendation ITU-T G.9805 (2022), Coexistence of passive optical network systems. | +| [ITU-T G.9807.1] | Recommendation ITU-T G.9807.1 (2016), 10-Gigabit-capable symmetric passive optical network (XGS-PON). | +| [ITU-T L.313] | Recommendation ITU-T L.313/L.66 (2007), Optical fibre cable maintenance criteria for in-service fibre testing in access networks. | + +# 3 Definitions + +This Recommendation makes frequent use of the terms defined in [ITU-T G.983.1], [ITU-T G.983.3] and [ITU-T G.984.2]. For purposes of convenience, the main definitions related to the G-PON enhancement bands are reported in this clause. + +### 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **10-Gigabit-capable passive optical network (XG-PON)**: [ITU-T G.987]. +- 3.1.2 **coexistence element (CE)**: [ITU-T G.989]. +- 3.1.3 **NG-PON2**: [ITU-T G.989]. +- 3.1.4 **optical distribution network (ODN)**: [ITU-T G.984.2]. +- 3.1.5 **optical line termination (OLT)**: [ITU-T G.984.2]. +- 3.1.6 **optical network unit (ONU)**: [ITU-T G.984.2]. +- 3.1.7 **PtP WDM PON**: [ITU-T G.989]. +- 3.1.8 **TWDM PON**: [ITU-T G.989]. +- 3.1.9 **wavelength division multiplexing (WDM)**: [ITU-T G.984.2]. +- 3.1.10 **wavelength multiplexer (WM)**: [ITU-T G.989]. +- 3.1.11 **XGS-PON**: [ITU-T G.9807.1]. + +### 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +- 3.2.1 **next generation access (NGA)**: A possible new optical access system that coexists with gigabit-capable passive optical network (G-PON) on the same optical distribution network (ODN). +- 3.2.2 **wavelength blocking filter (WBF)**: An optical filter to prevent an optical receiver from receiving unwanted optical signals with different wavelengths. + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|---------|-------------------------------------------------| +| APD | Avalanche Photo Diode | +| BER | Bit Error Rate | +| BM | Burst Mode | +| B-PON | Broadband Passive Optical Network | +| CDR | Clock Data Recovery | +| CE | Coexistence Element | +| CEM | Coexistence Element/Multiplexer | +| CNR | Carrier-to-Noise Ratio | +| DBA | Determined By Application | +| DFB | Distributed Feedback Laser | +| G-PON | Gigabit-capable Passive Optical Network | +| HSP | Higher Speed Passive Optical Network | +| LA | Limiting Amplifier | +| MPM | Multi-PON Module | +| NRZ | Non Return to Zero | +| NG-PON2 | Next Generation Passive Optical Network phase 2 | +| NGA | Next Generation Access | +| OAN | Optical Access Network | +| ODN | Optical Distribution Network | +| OLT | Optical Line Termination | +| ONU | Optical Network Unit | +| OPL | Optical Path Loss | +| OSA | Optical Sub-Assembly | +| OTDR | Optical Time-Domain Reflectometer | +| PLC | Planar Lightwave Circuit | +| PMD | Physical Media Dependent | +| PON | Passive Optical Network | +| PtP WDM | Point-to-Point Wavelength Division Multiplexing | +| RF | Radio Frequency | +| TIA | Trans-Impedance Amplifier | +| TDM | Time Division Multiplexing | +| TWDM | Time and Wavelength Division Multiplexing | +| WBF | Wavelength Blocking Filter | +| WDM | Wavelength Division Multiplexing | +| WM | Wavelength Multiplexer | + +| | | +|-----------|-----------------------------------------------| +| XG-PON | Asymmetric 10-Gigabit Passive Optical Network | +| XGS-PON | Symmetric 10-Gigabit Passive Optical Network | +| XG(S)-PON | XG-PON or XGS-PON | + +## 5 Conventions + +None. + +## 6 Reference architecture + +Figure 1, reproduced here for convenience from Figure 5 of [ITU-T G.983.1], shows the generic physical configuration of an optical access network (OAN). + +![Figure 1: Generic physical configuration of the optical access network. The diagram shows an Optical Line Termination (OLT) on the right connected to an Optical Distribution Network (ODN) in the center. The ODN is connected to multiple Optical Network Units (ONUs), labeled ONU1 and ONU_n. Each ONU is connected to the ODN via two optical interfaces, O_id and O_ru. The OLT is connected to the ODN via two optical interfaces, O_ld and O_lu. Reference points R/S are indicated at the ONU and OLT interfaces. A legend at the bottom defines the symbols: O_id, O_ru, O_ld, O_lu for optical interfaces; R and S for reference points; a solid line for one or more fibres; and a dashed line for optional protection fibres. The diagram is labeled G.984.5(14)-Amd.2(20)_F01.](b8661c6c54f72ecc7ff6cb05e47b2891_img.jpg) + +Figure 1: Generic physical configuration of the optical access network. The diagram shows an Optical Line Termination (OLT) on the right connected to an Optical Distribution Network (ODN) in the center. The ODN is connected to multiple Optical Network Units (ONUs), labeled ONU1 and ONU\_n. Each ONU is connected to the ODN via two optical interfaces, O\_id and O\_ru. The OLT is connected to the ODN via two optical interfaces, O\_ld and O\_lu. Reference points R/S are indicated at the ONU and OLT interfaces. A legend at the bottom defines the symbols: O\_id, O\_ru, O\_ld, O\_lu for optical interfaces; R and S for reference points; a solid line for one or more fibres; and a dashed line for optional protection fibres. The diagram is labeled G.984.5(14)-Amd.2(20)\_F01. + +**Figure 1 – Generic physical configuration of the optical access network** +(Reproduced from Figure 5 of [ITU-T G.983.1]) + +The two directions for optical transmission in the optical distribution network ODN are identified as follows: + +- downstream direction for signals travelling from the optical line termination (OLT) to the optical network unit(s) (ONU); +- upstream direction for signals travelling from the ONU(s) to the OLT. + +According to [ITU-T G.983.1], transmission in downstream and upstream directions can take place on the same fibre and components (duplex/diplex working) or on separate fibres and components (simplex working). This Recommendation covers only diplex working, i.e., bidirectional transmission using different wavelengths over a single fibre. + +There can be several types of ODN architectures to achieve the coexistence of gigabit-capable passive optical network (G-PON) and additional services including next generation access (NGA) and video distribution services. + +Figures 2 and 3 are reference diagrams of optical access network (OAN) architectures and assume that wavelength blocking filters (WBFs) are used when G-PON, video and NGA share the same ODN. + +Note that these reference diagrams only provide reference configurations of the ODN and WBF and are not intended to limit future designs and implementations. + +![Figure 2: Optical access network architecture reference diagram 1. This diagram shows a central office (OLT side) connected to various Optical Network Units (ONUs) via an Optical Distribution Network (ODN). The ODN contains a Splitter and a WDM1 element. The ONUs include: ONU (G-PON), ONU (G-PON + video), ONU (NGA), and ONU (NGA + video). Each ONU has internal components like Logic, Tx, Rx, WBF, and WDM-N. The OLT side includes OLT (G-PON), OLT (NGA), and OLT (video). Interfaces are labeled IFG-PON, IFNGA, and IFvideo.](5b4e774d63e0e0ed73801a9247755e5f_img.jpg) + +Detailed description of Figure 2: The diagram illustrates the connectivity between various types of ONUs and OLTs through an ODN. On the left, four ONU types are shown: ONU (G-PON), ONU (G-PON + video), ONU (NGA), and ONU (NGA + video). Each ONU contains a Logic block and transmitter (Tx)/receiver (Rx) components. Some include a video receiver (V-Rx) and Wavelength Blocking Filters (WBF, WBF-V). These connect to WDM modules (WDM-N, WDM-N', WDM-NGA, WDM-NGA'). The ODN in the center consists of a Splitter and a WDM1 block. On the right, the OLT side includes OLT (G-PON) with WDM-L, OLT (NGA) with WDM-NGA-L and multiple Rx/Tx pairs, and OLT (video) with a V-Tx. Interfaces are marked as IFG-PON, IFNGA, and IFvideo. + +Figure 2: Optical access network architecture reference diagram 1. This diagram shows a central office (OLT side) connected to various Optical Network Units (ONUs) via an Optical Distribution Network (ODN). The ODN contains a Splitter and a WDM1 element. The ONUs include: ONU (G-PON), ONU (G-PON + video), ONU (NGA), and ONU (NGA + video). Each ONU has internal components like Logic, Tx, Rx, WBF, and WDM-N. The OLT side includes OLT (G-PON), OLT (NGA), and OLT (video). Interfaces are labeled IFG-PON, IFNGA, and IFvideo. + +(NOTE – WDM1 can be replaced by WDM1r, CE or CEM.) + +**Figure 2 – Optical access network architecture reference diagram 1** + +![Figure 3: Optical access network architecture reference diagram 2. This diagram is similar to Figure 2 but uses a two-stage splitting architecture in the ODN. The first stage is a 'Splitter (1st stage, 3 by N)' and the second stage is a 'Splitter (2nd stage, 1 by M)'. The ONUs and OLTs are the same as in Figure 2. The interfaces are also labeled IFG-PON, IFNGA, and IFvideo.](d26959f4514c26ca19c3d6f00da85956_img.jpg) + +Detailed description of Figure 3: This diagram follows the same general structure as Figure 2 but modifies the ODN. Instead of a single splitter and WDM1, it features a two-stage splitting process. The first stage is labeled 'Splitter (1st stage, 3 by N)' which connects to the OLT side. The second stage is labeled 'Splitter (2nd stage, 1 by M)' which connects to the ONU side. The ONU and OLT configurations remain identical to Figure 2, including the logic, Tx/Rx components, and WDM modules. Interfaces IFG-PON, IFNGA, and IFvideo are maintained. + +Figure 3: Optical access network architecture reference diagram 2. This diagram is similar to Figure 2 but uses a two-stage splitting architecture in the ODN. The first stage is a 'Splitter (1st stage, 3 by N)' and the second stage is a 'Splitter (2nd stage, 1 by M)'. The ONUs and OLTs are the same as in Figure 2. The interfaces are also labeled IFG-PON, IFNGA, and IFvideo. + +**Figure 3 – Optical access network architecture reference diagram 2** + +The following abbreviations are used in Figures 2 and 3: + +- CE** Coexistence element that may be located in the central office to combine/isolate the wavelengths of next generation passive optical network phase 2 (NG-PON2) and legacy PON signals and which occasionally combines the video signals and/or OTDR signals +- CEM** Coexistence element that may be located in the central office to combine/isolate the wavelengths of TWDM PON, PtP WDM PON and legacy PON signals and which occasionally combines the video signals and/or OTDR signals + +| | | +|-----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Rx | Optical receiver | +| Tx | Optical transmitter | +| V-Rx | Video receiver | +| V-Tx | Video transmitter | +| WBF | Wavelength blocking filter for blocking interference signals to Rx | +| WBF-V | Wavelength blocking filter for blocking interference signals to V-Rx | +| WDM-N | WDM filter in G-PON ONU to combine/isolate the wavelengths of G-PON upstream and downstream | +| WDM-N' | WDM filter in G-PON ONU to combine/isolate the wavelengths of G-PON upstream and downstream and isolate the video signal(s) | +| WDM-NGA | WDM filter in NGA ONU to combine/isolate the wavelengths of NGA upstream and downstream | +| WDM-NGA' | WDM filter in NGA ONU to combine/isolate the wavelengths of NGA upstream and downstream and isolate the video signal(s) | +| WDM-L | WDM filter in G-PON OLT to combine/isolate the wavelengths of G-PON upstream and downstream | +| WDM-NGA-L | WDM filter in NGA OLT to combine/isolate the wavelengths of NGA upstream and downstream of one or more channels | +| WDM1 | WDM filter that may be located in the central office to combine/isolate the wavelengths of G-PON and NGA signals and which occasionally combines the video signals and/or OTDR signals | +| WDM1r | WDM filter that may be located in the central office to combine/isolate the wavelengths of G-PON and XG-PON signals and which occasionally combines the video signals and/or OTDR signals. | + +## 7 Operating wavelength + +The wavelength range of the G-PON downstream signal (single fibre system) is specified in [ITU-T G.984.2] as 1480 nm to 1500 nm and that of the G-PON upstream signal as 1260 nm to 1360 nm. This Recommendation redefines the reserved wavelength range and specifies the tolerance for interference signals of G-PON ONUs to enable the coexistence of G-PON and additional services including NGA and video services. + +Figure 4 and Table 1 define the wavelength allocation plan including the wavelength bands reserved for additional services. The wavelength range of the G-PON downstream signal is referred to as the "basic band". Reserved bands are referred to as the "enhancement band". Applications for the enhancement band include video services and NGA services. The wavelength range for video services remains as defined in [ITU-T G.983.3]. + +A guard band separates the G-PON upstream and/or basic band from the enhancement band. Interference between signals in these two bands causes signal degradation to each. This signal degradation must be kept to a negligible level. Wavelength blocking filters (WBFs) are used to obtain the required isolation outside the guard band. The wavelength values specified in Table 1 take into account guard bands that may be achievable by commercially available low-cost WBFs. + +NOTE – Wavelengths in the enhancement band may be used not only for downstream but also for upstream signal transmission in the WDM scheme. + +![Figure 4 – Wavelength allocation diagram showing three wavelength bands: 1.3 μm (upstream), Intermediate (upstream/downstream), and 1.5 μm (upstream/downstream).](af7916c89a458fdab6c3f443217388ae_img.jpg) + +The diagram illustrates wavelength allocation across three bands: + +- 1.3 μm wavelength band (upstream):** A green block labeled "G-PON upstream" spans from $\lambda 1$ to $\lambda 2$ . The overall band limits are 1260 nm and 1360 nm. +- Intermediate wavelength band (upstream and/or downstream):** A green block labeled "Enhancement band (option 1)" spans from $\lambda 3$ to $\lambda 4$ . Guard bands for upstream and downstream are shown on either side. The overall band limits are 1360 nm and 1480 nm. +- 1.5 μm wavelength band (upstream and/or downstream):** A blue block labeled "G-PON downstream" (Basic Band) spans from 1480 nm to 1500 nm. A green block labeled "Enhancement band (option 2)" spans from $\lambda 5$ to $\lambda 6$ . A yellow block labeled "Video (option 3)" is positioned between 1550 nm and 1560 nm. Guard bands for downstream are shown between the Basic Band and the Enhancement band. + +G.984.5(07)\_F04 + +Figure 4 – Wavelength allocation diagram showing three wavelength bands: 1.3 μm (upstream), Intermediate (upstream/downstream), and 1.5 μm (upstream/downstream). + +**Figure 4 – Wavelength allocation** + +**Table 1 – Parameters for wavelength allocation** + +| Items | Notation | Unit | Nominal value | Application examples | | +|----------------------------------|-------------|------|-------------------------------|----------------------|------------------------------------------------------------------------------------------------| +| 1.3 μm wavelength band | | | | | For use in G-PON upstream. | +| – Regular wavelength band option | | | | | | +| Lower limit | $\lambda 1$ | nm | 1 260 | | e.g., ONUs based on Fabry-Perot lasers. | +| Upper limit | $\lambda 2$ | nm | 1 360 | | | +| – Reduced wavelength band option | | | | | | +| Lower limit | $\lambda 1$ | nm | 1 290 | | e.g., ONUs based on ordinary DFB lasers. | +| Upper limit | $\lambda 2$ | nm | 1 330 | | | +| – Narrow wavelength band option | | | | | | +| Lower limit | $\lambda 1$ | nm | 1 300 | | e.g., ONUs based on wavelength selected lasers. | +| Upper limit | $\lambda 2$ | nm | 1 320 | | | +| Enhancement band (option 1-1) | | | | | | +| Lower limit | $\lambda 3$ | nm | 1 415
(Informative) | | For next generation access (NGA).
(See Note 2) | +| Upper limit | $\lambda 4$ | nm | 1 450
(Informative) | | | +| Enhancement band (option 1-2) | | | | | | +| Lower limit | $\lambda 3$ | nm | 1 400
(Informative) | | For next generation access (NGA).
Applicable for low-water-peak fibre only.
(See Note 3) | +| Upper limit | $\lambda 4$ | nm | 1 450
(Informative) | | | + +**Table 1 – Parameters for wavelength allocation** + +| Items | Notation | Unit | Nominal value | Application examples | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|------|----------------|--------------------------------------------------------------| +| Basic band | | | | | +| Lower limit | – | nm | 1 480 | For use in G-PON downstream. | +| Upper limit | – | nm | 1 500 | | +| Enhancement band (option 2, see Note 1) | | | | | +| Lower limit | $\lambda 5$ | nm | 1 530 | For next generation access (NGA).
(See Note 4 and Note 5) | +| Upper limit | $\lambda 6$ | nm | 1 580 to 1 625 | | +| Enhancement band (option 3, see Note 1) | | | | | +| Lower limit | – | nm | 1 550 | For video distribution service. | +| Upper limit | – | nm | 1 560 | | +| NOTE 1 – Additional guard bands are needed in the case of the coexistence of option 2 and option 3 (see Appendix II). | | | | | +| NOTE 2 – The values are informative. The loss in this band is not guaranteed in optical branching components for PON (i.e., power splitters) as specified in [ITU-T G.671] nor in optical fibres specified as G.652A and G.652B (non-low-water-peak fibres). | | | | | +| NOTE 3 – The values are informative. The loss in this band is not guaranteed in optical branching components for PON (i.e., power splitters) as specified in [ITU-T G.671]. | | | | | +| NOTE 4 – The value of 1530 nm assumes use of the wavelength for downstream NGA transmission. If it is used for upstream transmission, the value can be smaller. | | | | | +| NOTE 5 – The upper-limit value is determined as an operator choice from 1580 to 1625 nm taking into account the following factors:
  • – Bending loss of optical fibre that increases at longer wavelengths.
  • – Loss of a filter that separates/combines a monitoring signal and NGA signal(s) (if an optical monitoring system is used).
| | | | | + +## 8 X/S tolerance of G-PON ONU + +The minimum optical sensitivity requirements of a G-PON ONU must be met in the presence of the interference signals caused by NGA and/or video signals in the enhancement bands specified in Table 1. To minimize the effect of interference signals, G-PON ONUs need to isolate interference signals using an appropriate WBF and WDM filter. This Recommendation does not specify the isolation characteristics of the WBF and WDM filters themselves, but does specify the X/S tolerance of the G-PON ONU. + +In Figure 5, S is the optical power of the basic band signal, and X is the optical power of the interference signal(s). Both S and X are measured at the point IFG-PON on the optical network unit (ONU) side of the network shown in Figures 2 and 3. Figure 5 shows the X/S tolerance mask that should not cause the sensitivity of the basic band receiver to fail to meet the specified limit. Implementers need to specify the isolation characteristics of the WBF and WDM filter needed to obtain enough isolation of the interference signal(s) that will allow the sensitivity requirements to be respected in the presence of this level of interference. In the case of coexistence with G-PON, the wavelengths and total optical launch power of additional services including NGA and video services must be considered with reference to Figure 5. + +The interference signal format for measuring X/S tolerance should be non-return to zero (NRZ) pseudo-random coded with the same bit rate as the G-PON downstream signal or with a lower bit rate within the bandwidth of the basic band receiver. + +![Graph showing X relative to S (dB) vs Wavelength (nm) for ONU. The graph shows a tolerance mask with two hatched regions. The y-axis is labeled 'X relative to S (dB)' with markers y1 and y2. The x-axis is labeled 'Wavelength (nm)' with markers λ3, λ4', λ4, 1480, 1500, λ5, λ5', λ6'. A 'Basic band' is indicated between 1480 and 1500 nm. The mask levels are y2 from λ3 to λ4', y1 from λ4 to λ5, and y2 from λ5' to λ6'. The text 'G.984.5(07)_F05' is in the bottom right.](71ab4df17511d75261da8d462d643b1a_img.jpg) + +Graph showing X relative to S (dB) vs Wavelength (nm) for ONU. The graph shows a tolerance mask with two hatched regions. The y-axis is labeled 'X relative to S (dB)' with markers y1 and y2. The x-axis is labeled 'Wavelength (nm)' with markers λ3, λ4', λ4, 1480, 1500, λ5, λ5', λ6'. A 'Basic band' is indicated between 1480 and 1500 nm. The mask levels are y2 from λ3 to λ4', y1 from λ4 to λ5, and y2 from λ5' to λ6'. The text 'G.984.5(07)\_F05' is in the bottom right. + +| Wavelength (nm) | λ3 | λ4' | λ4 | λ5 | λ5' | λ6' | +|----------------------|-----------------------------------|------------------------------|------------------------------|------|------|------| +| | 1415/1400
(Informative) | 1441
(Informative) | 1450
(Informative) | 1530 | 1539 | 1675 | +| X relative to S (dB) | y2 | y2 | y1 | y1 | y2 | y2 | +| | 22
(Informative) | 22
(Informative) | 7
(Informative) | 7 | 22 | 22 | + +S Received power of basic band + +X Maximum total power of NGA and video received in the blocking wavelength range + +X/S Inside the mask (hatching area) should not cause the sensitivity of the basic band receiver to fail to meet the specified limit + +NOTE – λ3 value of 1400 *(Informative)* may be applicable for low-water-peak fibre only. + +**Figure 5 – X/S tolerance mask for ONU** + +## Appendix I + +### **Example of WDM1, WDM1r, CEx and CEMx characteristics** + +(This appendix does not form an integral part of this Recommendation.) + +The WDM1, WDM1r, CEx and CEMx devices can have several different configurations depending on whether a video overlay service or an optical time-domain reflectometer (OTDR) is provided. Appendix I of [ITU-T G.9805] presents several examples of device characteristics. + +## Appendix II + +### Examples of wavelength allocation for NGA services and video distribution services + +(This appendix does not form an integral part of this Recommendation.) + +### II.1 Introduction + +Considering the possible network scenarios that allow the coexistence of G-PON, NGA and video services, it is assumed that additional guard bands are needed at both sides of the video band to avoid interference which could cause the degradation of video carrier-to-noise ratio (CNR) performances of the video receiver. To take the guard bands for both basic band and video into account, the wavelength range between basic band and video may not be applicable for NGA downstream signals. Figure II.1 shows the wavelength plan of the 1.5 $\mu\text{m}$ wavelength band for these scenarios. The ranges of the guard bands depend on the filter characteristics of the video band pass filter and the performance of the video receiver. In this clause, two types of filters are considered. One is the integrated filter within the G-PON ONU transceiver such as triplexer type transceiver and the other is the discrete filter outside of the G-PON diplexer type transceiver and the video receiver. The examples of wavelength allocation and filter characteristics for each case are provided in clauses II.2 and II.3. + +![Figure II.1: Wavelength allocation diagram showing the 1500 nm wavelength band. The diagram illustrates three main bands: Basic band (G-PON downstream) from 1480 to 1500 nm, Video (option 3) from 1550 to 1560 nm, and Enhancement band (option 4) from 1560 to 1580 nm. A guard band is indicated between the Video band and the Enhancement band, starting at 1560 nm and extending to a wavelength labeled λ7. The wavelength axis is marked at 1480, 1500, 1550, 1560, λ7, and 1580 nm. A small label G.984.5(07)_FII.1 is present in the bottom right corner.](a706c91f074ac2840c161a3d4a7c0f91_img.jpg) + +1500 nm wavelength band (coexistence of G-PON, video and NGA) + +Basic band + +G-PON downstream + +Video (option 3) + +Guard band + +Enhancement band (option 4) + +1480 1500 1550 1560 $\lambda 7$ 1580 + +G.984.5(07)\_FII.1 + +Figure II.1: Wavelength allocation diagram showing the 1500 nm wavelength band. The diagram illustrates three main bands: Basic band (G-PON downstream) from 1480 to 1500 nm, Video (option 3) from 1550 to 1560 nm, and Enhancement band (option 4) from 1560 to 1580 nm. A guard band is indicated between the Video band and the Enhancement band, starting at 1560 nm and extending to a wavelength labeled λ7. The wavelength axis is marked at 1480, 1500, 1550, 1560, λ7, and 1580 nm. A small label G.984.5(07)\_FII.1 is present in the bottom right corner. + +Figure II.1 – Wavelength allocation + +### II.2 Case 1: Integrated filter for video + +Figure II.2 shows an example configuration of a G-PON ONU using a triplexer type transceiver including an integrated video filter. This figure does not intend to limit filter configurations of the triplexer. Filter configurations may be different in each implementation and also depend on the implementations of optics (e.g., micro-optics or planar lightwave circuit (PLC) based). In this figure, the isolation values at the reference point are the sum of the isolation values of the WDM filter and the wavelength blocking filter (WBF) in front of the V-Rx. Figure II.3 shows an example of isolation and Table II.1 shows an example of wavelength allocation including the tentative wavelength value of $\lambda 7$ in Figure II.3. One of the example isolation values of $y_3$ in Figure II.3 is 30 dB with reference to the realistic isolation performances of an integrated filter. Service operators and implementers should take the actual filter characteristics and performance of the video receiver into account when considering additional enhanced services. + +![Block diagram of a G-PON ONU with video. The diagram shows a 'G-PON MAC and SerDes' connected to a 'Triplexer'. The 'Triplexer' is connected to a 'G-PON Rx' and a 'G-PON Tx'. The 'G-PON Tx' is connected to a 'WDM filter' (blue rectangle), which is connected to a 'Wavelength blocking filter' (green rectangle). The 'Wavelength blocking filter' is connected to a 'Reference point' (circle), which is connected to a 'V-Rx'. The 'V-Rx' is connected to an 'RF out'. The 'G-PON Rx' is connected to a 'Wavelength blocking filter' (green rectangle), which is connected to a 'WDM filter' (blue rectangle). The 'WDM filter' is connected to an 'Optical signal over ODN fibre'. The 'Data in/out' is connected to the 'G-PON MAC and SerDes'. A legend at the bottom identifies the symbols: blue rectangle for 'WDM filter', green rectangle for 'Wavelength blocking filter', and circle for 'Reference point'. The text 'G.984.5(07)_FII.2' is in the bottom right.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +Block diagram of a G-PON ONU with video. The diagram shows a 'G-PON MAC and SerDes' connected to a 'Triplexer'. The 'Triplexer' is connected to a 'G-PON Rx' and a 'G-PON Tx'. The 'G-PON Tx' is connected to a 'WDM filter' (blue rectangle), which is connected to a 'Wavelength blocking filter' (green rectangle). The 'Wavelength blocking filter' is connected to a 'Reference point' (circle), which is connected to a 'V-Rx'. The 'V-Rx' is connected to an 'RF out'. The 'G-PON Rx' is connected to a 'Wavelength blocking filter' (green rectangle), which is connected to a 'WDM filter' (blue rectangle). The 'WDM filter' is connected to an 'Optical signal over ODN fibre'. The 'Data in/out' is connected to the 'G-PON MAC and SerDes'. A legend at the bottom identifies the symbols: blue rectangle for 'WDM filter', green rectangle for 'Wavelength blocking filter', and circle for 'Reference point'. The text 'G.984.5(07)\_FII.2' is in the bottom right. + +**Figure II.2 – Example configuration of G-PON ONU with video (Case 1)** + +![Graph showing integrated filter characteristics for video. The y-axis is 'Isolation (dB)' and the x-axis is 'Wavelength (nm)'. The graph shows a filter response curve with a peak isolation of y3 dB at 1550 nm. A blue rectangle highlights the enhancement band from 1550 nm to 1560 nm. The isolation at 1560 nm is 0.5 dB. The curve drops to a lower isolation level at 1570 nm (λ7) and remains low until 1580 nm (λ6). The text 'G.984.5(07)_FII.3' is in the bottom right.](b6750d26d3dd287a4a4d49b3670a44bd_img.jpg) + +Graph showing integrated filter characteristics for video. The y-axis is 'Isolation (dB)' and the x-axis is 'Wavelength (nm)'. The graph shows a filter response curve with a peak isolation of y3 dB at 1550 nm. A blue rectangle highlights the enhancement band from 1550 nm to 1560 nm. The isolation at 1560 nm is 0.5 dB. The curve drops to a lower isolation level at 1570 nm (λ7) and remains low until 1580 nm (λ6). The text 'G.984.5(07)\_FII.3' is in the bottom right. + +**Figure II.3 – Example of integrated filter characteristics for video** + +**Table II.1 – Example of wavelength allocation (Case 1)** + +| Items | Notation | Unit | Nominal value | Application examples | +|---------------------------------------------------------------------------------------------------|----------|------|---------------------------------|----------------------------------| +| Enhancement band (option 3) | | | | | +| Lower limit | – | nm | 1550 | For video distribution service | +| Upper limit | – | nm | 1560 | | +| Enhancement band (option 4) | | | | | +| Lower limit | λ7 | nm | To be determined (1574 or 1575) | For next generation access (NGA) | +| Upper limit | λ6 | nm | 1580 to 1625 | | +| NOTE – Typically applied to the integrated filters inside the triplexer type optical transceiver. | | | | | + +### II.3 Case 2: Discrete WDM filter for video + +Figures II.4 and II.5 show example configurations of a G-PON ONU (and a video ONU) using discrete WDM filters. These figures do not intend to limit filter configurations. In these figures, the isolation values at the reference point are the sum of the isolation values of the discrete WDM filter and the WBF in front of the V-Rx. Figure II.6 shows an example of isolation and Table II.2 shows an example of wavelength allocation. One of the example isolation values of y4 in Figure II.6 is 35 dB with reference to the realistic isolation performances of a discrete filter. Service operators and implementers should take actual filter characteristics and performance of the video receiver into account when considering additional enhanced services. + +![Figure II.4: Example configuration of G-PON ONU with video (Case 2).](2b3a967f6ce4f23649be995a353e39f8_img.jpg) + +This block diagram illustrates the internal components and signal flow of a G-PON ONU with video. On the left, 'Data in/out' connects to a 'G-PON MAC and SerDes' block. This block is connected to a 'Diplexer'. The 'Diplexer' has two output paths: one to a 'G-PON Rx' block and another to a 'G-PON Tx' block. The 'G-PON Tx' block is connected to a blue 'WDM filter'. The 'WDM filter' is connected to an external 'Optical signal over ODN fibre'. Below the 'WDM filter', there is a green 'Wavelength blocking filter', a circle representing a 'Reference point', and a 'V-Rx' block. The 'V-Rx' block is connected to an 'RF out' terminal. A legend at the bottom identifies the blue rectangle as a 'WDM filter', the green rectangle as a 'Wavelength blocking filter', and the circle as a 'Reference point'. The diagram is labeled 'G.984.5(07)\_FII.4'. + +Figure II.4: Example configuration of G-PON ONU with video (Case 2). + +Figure II.4 – Example configuration of G-PON ONU with video (Case 2) + +![Figure II.5: Example configuration of G-PON ONU and video ONU (Case 2).](10781f43062bf3e9601a1e086710556c_img.jpg) + +This block diagram shows the configuration for a G-PON ONU without video connected to a separate Video ONU. The 'G-PON ONU without video' section on the left is identical to the one in Figure II.4, with 'Data in/out', 'G-PON MAC and SerDes', 'Diplexer', 'G-PON Rx', 'G-PON Tx', and a blue 'WDM filter'. The 'WDM filter' connects to an external 'Optical signal over ODN fibre'. This optical signal then enters a 'Video ONU' block. Inside the 'Video ONU', the signal passes through a green 'Wavelength blocking filter', a circle representing a 'Reference point', and a 'V-Rx' block. The 'V-Rx' block is connected to an 'RF out' terminal. A legend at the bottom identifies the blue rectangle as a 'WDM filter', the green rectangle as a 'Wavelength blocking filter', and the circle as a 'Reference point'. The diagram is labeled 'G.984.5(07)\_FII.5'. + +Figure II.5: Example configuration of G-PON ONU and video ONU (Case 2). + +Figure II.5 – Example configuration of G-PON ONU and video ONU (Case 2) + +![Figure II.6: Example of discrete filter characteristics for video ONU. The graph shows Isolation (dB) on the y-axis and Wavelength (nm) on the x-axis. A passband filter is centered between 1550 nm and 1560 nm, with a peak isolation labeled y4 and a top ripple of 0.5 dB. To the right, a blue rectangular region represents another band between λ7' and λ6.](3102c32204f998dba666e1e915d5babf_img.jpg) + +Figure II.6 is a graph of Isolation (dB) vs Wavelength (nm). The x-axis starts at 1500 and has markers at 1550, 1560, λ7', and λ6. A bell-shaped curve represents a filter with a flat top between 1550 and 1560 nm. The height of this flat top is indicated by a vertical double-headed arrow labeled y4. A small vertical double-headed arrow at the top right of this peak indicates a 0.5 dB margin. A blue shaded rectangle is shown between the 1550 and 1560 markers. Another blue shaded rectangle starts at wavelength λ7' and extends to λ6. The label G.984.5(07)\_FII.6 appears at the bottom right. + +Figure II.6: Example of discrete filter characteristics for video ONU. The graph shows Isolation (dB) on the y-axis and Wavelength (nm) on the x-axis. A passband filter is centered between 1550 nm and 1560 nm, with a peak isolation labeled y4 and a top ripple of 0.5 dB. To the right, a blue rectangular region represents another band between λ7' and λ6. + +**Figure II.6 – Example of discrete filter characteristics for video ONU** + +**Table II.2 – Example of wavelength allocation (Case 2)** + +| Items | Notation | Unit | Nominal value | Application examples | +|-----------------------------|--------------|------|-------------------|----------------------------------| +| Enhancement band (option 3) | | | | | +| Lower limit | – | nm | 1550 | For video distribution service | +| Upper limit | – | nm | 1560 | | +| Enhancement band (option 5) | | | | | +| Lower limit | $\lambda 7'$ | nm | For further study | For next generation access (NGA) | +| Upper limit | $\lambda 6$ | nm | 1580 to 1625 | | + +## Bibliography + +- [b-ITU-T G-Sup.39] ITU-T G-series Recommendations – Supplement 39 (2016), *Optical system design and engineering considerations*. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git 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the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.985** + +(03/2003) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical line +systems for local and access networks + +--- + +**100 Mbit/s point-to-point Ethernet based optical +access system** + +ITU-T Recommendation G.985 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **ITU-T Recommendation G.985** + +# **100 Mbit/s point-to-point Ethernet based optical access system** + +# **Summary** + +This Recommendation describes the 100 Mbit/s point-to-point Ethernet based optical access system, including ODN (optical distribution network) specification, physical layer specification and the requirements for the OAM (operation, administration and maintenance). This Recommendation is based on 1-fiber WDM bidirectional transmission system. + +###### **Source** + +ITU-T Recommendation G.985 was prepared by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 16 March 2003. + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2003 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# CONTENTS + +###### Page + +| | | | +|------|---------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 1 | +| 4 | Abbreviations..... | 2 | +| 5 | Configuration of an OAN ..... | 2 | +| 5.1 | System configuration..... | 2 | +| 5.2 | Fibre type..... | 3 | +| 5.3 | Transmission methodology ..... | 3 | +| 5.4 | Wavelength allocation ..... | 3 | +| 5.5 | ODN model ..... | 3 | +| 5.6 | Class for optical path loss..... | 4 | +| 5.7 | Reflectance in ODN ..... | 4 | +| 6 | Physical layer specification ..... | 4 | +| 6.1 | Transmit wavelength/Receive wavelength..... | 6 | +| 6.2 | Bit rate and line coding..... | 6 | +| 6.3 | Spectral characteristics ..... | 6 | +| 6.4 | Mean launched power..... | 6 | +| 6.5 | Receiver characteristics ..... | 7 | +| 6.6 | Extinction ratio ..... | 7 | +| 6.7 | Pulse mask ..... | 7 | +| 6.8 | S/X..... | 7 | +| 6.9 | Optical return loss of the interface ..... | 7 | +| 6.10 | Test pattern ..... | 8 | +| 6.11 | Jitter ..... | 8 | +| 6.12 | Signal detect ..... | 8 | +| 6.13 | Optical connector..... | 8 | +| 7 | Requirements for the OAM ..... | 8 | +| 7.1 | General requirements..... | 8 | +| 7.2 | Requirements for the OAM functions ..... | 9 | +| 7.3 | Managed entities..... | 10 | +| 7.4 | Requirements for the OAM signals and sequences ..... | 11 | +| 7.5 | Requirements for the performance monitor function ..... | 11 | + + + +# 100 Mbit/s point-to-point Ethernet based optical access system + +# 1 Scope + +This Recommendation describes 100 Mbit/s point-to-point Ethernet based optical access system for the optical access services including ODN (optical distribution network) specification, physical layer specification and the requirements for the OAM (operation, administration and maintenance). + +For an effective use of optical fibres, this Recommendation specifies only a single fibre bi-directional transmission system, dual-fibre systems being out of the scope of this Recommendation. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation + +- [1] ITU-T Recommendation G.957 (1999), *Optical interfaces for equipments and systems relating to the synchronous digital hierarchy*. +- [2] ITU-T Recommendation G.982 (1996), *Optical access networks to support services up to the ISDN primary rate or equivalent bit rates*. +- [3] ITU-T Recommendation G.983.1 (1998), *Broadband optical access systems based on Passive Optical Networks (PON)*. +- [4] ITU-T Recommendation G.652 (2003), *Characteristics of a single-mode optical fibre cable*. +- [5] IEEE Standard 802.3-2000, *Information technology – LAN/MAN – Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications*. + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 Optical Access Network (OAN):** The set of access links sharing the same network-side interfaces and supported by optical access transmission systems. + +**3.2 Optical Distribution Network (ODN):** An ODN provides the optical transmission means from the OLT towards the users, and vice versa. It utilizes passive optical components. + +**3.3 Optical Line Termination (OLT):** An OLT provides the network-side interface of the OAN, and is connected to the ODN. + +**3.4 Optical Network Termination (ONT):** An ONT provides the user-side interface of the OAN, and is connected to the ODN. + +**3.5 Wavelength Division Multiplexing (WDM):** Bidirectional multiplexing using different optical wavelength for up and downstream signals. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------|-------------------------------------------| +| CRC | Cyclic Redundancy Check | +| FEFI | Far End Fault Indication | +| MII | Media Independent Interface | +| MLM | Multi-Longitudinal Mode | +| NRZI | Non Return to Zero Inverted | +| OAM | Operation, Administration and Maintenance | +| OAN | Optical Access Network | +| ODN | Optical Distribution Network | +| OLT | Optical Line Termination | +| ONT | Optical Network Termination | +| PCS | Physical Coding Sub-layer | +| PMA | Physical Medium Attachment | +| PMD | Physical Medium Dependent | +| RMS | Root Mean Square | +| RS | Reconciliation Sub-layer | +| SLM | Single Longitudinal Mode | +| SMF | Single Mode Fibre | +| SNI | Service Network Interface | +| UNI | User Network Interface | +| UTP | Unshielded Twisted Pair cable | +| WDM | Wavelength Division Multiplexing | + +# 5 Configuration of an OAN + +## 5.1 System configuration + +Figure 1 shows the system configuration of the point-to-point Ethernet based optical access system. In this Recommendation, both UNI and SNI are Ethernet interfaces. + +The two directions for optical transmission in the ODN are identified as follows: + +- downstream direction for signals travelling from the OLT to the ONT; +- upstream direction for signals travelling from the ONT to the OLT. + +![Diagram of system configuration showing ONT, ODN (point-to-point), OLT, and Service network connected via UNI, R/S, S/R, and SNI interfaces.](e1a0d046fbe7f28f5e93a47091851747_img.jpg) + +The diagram illustrates the system configuration of a point-to-point Ethernet based optical access system. It shows a sequence of components connected linearly from left to right: a UNI (User Network Interface) symbol, an ONT (Optical Network Termination) box, an R/S (Reconciliation Sub-layer) reference point, a dashed box labeled 'ODN (point-to-point)', an S/R (Physical Medium Dependent) reference point, an OLT (Optical Line Termination) box, an SNI (Service Network Interface) symbol, and a circle labeled 'Service network'. Below the diagram, the text 'R/S Reference points' is present. In the bottom right corner, the text 'G.985\_F01' is visible. + +Diagram of system configuration showing ONT, ODN (point-to-point), OLT, and Service network connected via UNI, R/S, S/R, and SNI interfaces. + +**Figure 1/G.985 – System configuration** + +## 5.2 Fibre type + +Single-mode fibre should be used in accordance with ITU-T Rec. G.652. + +## 5.3 Transmission methodology + +Bidirectional transmission is accomplished by use of Wavelength Division Multiplexing (WDM) technique of 1310 nm region and 1550 nm region wavelengths on a single fibre, allowing the connection to be a point-to-point type ODN. + +## 5.4 Wavelength allocation + +For downstream, the operating wavelength range should be 1260-1360 nm. + +For upstream, the operating wavelength range should be 1480-1580 nm. + +These wavelength ranges are compatible with ITU-T Rec. G.982 though it specifies point-to-multipoint configuration. + +## 5.5 ODN model + +The ODN provides the optical transmission medium for the physical connection between ONT and OLT. + +The ODN for the point-to-point configuration consists of passive optical elements as follows: + +- single-mode optical fibres and cables; +- optical fibre ribbons and ribbon cables; +- optical connectors; +- passive optical attenuators; +- splices. + +The ODN is defined between the reference points S and R. In analogy with the definitions provided in ITU-T Rec. G.957, S and R are defined as follows: + +- S: Point on the optical fibre just after the OLT/ONT optical connection point (i.e., optical connector or optical splice). +- R: Point on the optical fibre just before the OLT/ONT optical connection point (i.e., optical connector or optical splice). + +Because of the 1-fibre bidirectional transmission, the point S and R at each end of the ODN are located on the same fibre. + +The optical properties of the ODN shall enable the provision of any presently foreseeable service without the need of extensive modifications to the ODN itself. A set of essential items, which have a direct influence on the optical properties of the ODN, are identified as follows: + +- Optical wavelength transparency: Devices, which are not intended to perform any wavelength-selective function, shall be able to support transmission of signals at any wavelength in the 1310 nm and 1550 nm regions. +- Reciprocity: Reversal of input and output ports shall not cause significant change of the optical loss through the device. +- Fibre compatibility: All optical components shall be compatible with single-mode fibre as specified in ITU-T Rec. G.652. + +If additional connectors or other passive devices are needed for ODN rearrangement, they shall be located between the reference points S and R and their losses shall be taken into account in any optical loss calculation. + +## 5.6 Class for optical path loss + +Recommended classes for optical path loss are shown in Table 1. + +**Table 1/G.985 – Classes for optical path loss** + +| | Class S | Class A | Class B | +|--------------|---------|-------------------|-------------------| +| Minimum loss | 0 dB | For further study | For further study | +| Maximum loss | 15 dB | For further study | For further study | + +Class A and B are for further study. Class A is for the transmission within 20 km of distance and Class B is for the transmission within 30 km of distance. + +## 5.7 Reflectance in ODN + +The reflectance of an ODN depends on the return loss characteristics of the individual components along the optical path and on any reflection points existing in the ODN. A reflection model is described in 6.8. + +# 6 Physical layer specification + +The optical interface of ONT and OLT should follow the transmission and coding specification in conformance with PMA, PCS, MII, RS of 100 BASE-FX (IEEE Standard 802.3), except for the physical layer specification defined in this Recommendation. Physical layer specification is also specified for each of the following applicable areas. + +- Class S: optical path loss 15 dB, Power penalty 1 dB. +- Class A: For further study. The transmission distance is assumed to be within 20 km. +- Class B: For further study. The transmission distance is assumed to be within 30 km. + +NOTE – The distance described above is not a standard, but for classification. + +This physical layer specification describes PMD sub-layer on the layer structure in Figure 2. + +![Diagram showing the layer structure for OLT/ONT. It consists of two vertical stacks of layers. The left stack (for SMF) includes: Repeater or higher layer function, RS, MII, OAM sub-layer, MII, PCS, PMA, and PMD. The right stack (for UTP) includes: Repeater or higher layer function, RS, MII, PCS, PMA, and PMD. Both stacks connect to a 'Medium' (SMF on the left, UTP on the right). A callout line points from the text 'Specified in this clause' to the PMD layer in the left stack. The diagram is labeled G.985_F02.](fc69ceb1dee1da7e33bd6c38fc4ceab9_img.jpg) + +Diagram showing the layer structure for OLT/ONT. It consists of two vertical stacks of layers. The left stack (for SMF) includes: Repeater or higher layer function, RS, MII, OAM sub-layer, MII, PCS, PMA, and PMD. The right stack (for UTP) includes: Repeater or higher layer function, RS, MII, PCS, PMA, and PMD. Both stacks connect to a 'Medium' (SMF on the left, UTP on the right). A callout line points from the text 'Specified in this clause' to the PMD layer in the left stack. The diagram is labeled G.985\_F02. + +**Figure 2/G.985 – Index of clause 6 in the layer structure** + +All parameters are specified as follows, and should be in accordance with Table 2 for an ONT, and Table 3 for an OLT. + +**Table 2/G.985 – Physical layer specification for ONT** + +| Items | Unit | Specification | | | +|----------------------------------------------------|--------|------------------------------------------|-------------------|-------------------| +| ODN class | | Class S | Class A | Class B | +| Nominal bit rate | Mbit/s | 125 | | | +| Transmit wavelength | nm | 1260-1360 | | | +| Receive wavelength | nm | 1480-1580 | | | +| Line code | – | NRZI and 4B5B block coding | | | +| Spectral characteristic | | | For further study | For further study | +| If MLM laser – Maximum RMS width | nm | 7.7 | | | +| If SLM laser – Maximum –20 dB width | nm | For further study | | | +| If SLM laser – Minimum side mode suppression ratio | dB | For further study | | | +| Mean launch power MAX | dBm | –8 | | | +| Mean launch power MIN | dBm | –14 | | | +| Minimum overload | dBm | –8 | | | +| Minimum sensitivity | dBm | –30 | | | +| Power penalty | dB | 1 | | | +| Extinction ratio | dB | More than 8.2 | | | +| Pulse mask | | Conformance with ITU-T Rec. G.957, STM-1 | | | +| S/X | | | For further study | For further study | +| Optical return loss condition | dB | More than 14 | | | +| Bit error ratio | | Less than $10^{-10}$ | | | +| Optical return loss of the interface | dB | More than 14 | | | + +**Table 3/G.985 – Physical layer specification for OLT** + +| Items | Unit | Specification | | | +|----------------------------------------------------|--------|------------------------------------------|-------------------|-------------------| +| ODN class | | Class S | Class A | Class B | +| Nominal bit rate | Mbit/s | 125 | | | +| Transmit wavelength | nm | 1480-1580 | | | +| Receive wavelength | nm | 1260-1360 | | | +| Line code | – | NRZI and 4B5B block coding | | | +| Spectral characteristic | | | | | +| If MLM laser – Maximum RMS width | nm | 6 | For further study | For further study | +| If SLM laser – Maximum –20 dB width | nm | For further study | | | +| If SLM laser – Minimum side mode suppression ratio | dB | For further study | | | +| Mean launch power MAX | dBm | –8 | | | +| Mean launch power MIN | dBm | –14 | | | +| Minimum overload | dBm | –8 | | | +| Minimum sensitivity | dBm | –30 | | | +| Power penalty | dB | 1 | | | +| Extinction ratio | dB | More than 8.2 | | | +| Pulse mask | | Conformance with ITU-T Rec. G.957, STM-1 | | | +| S/X | | | | | +| Optical return loss condition | dB | More than 14 | For further study | For further study | +| Bit error ratio | | Less than $10^{-10}$ | | | +| Optical return loss of the interface | dB | More than 14 | | | + +## 6.1 Transmit wavelength/Receive wavelength + +Transmit and receive wavelength are described in 5.3 and 5.4. + +## 6.2 Bit rate and line coding + +Bit rate of both upstream and downstream is 125 Mbit/s, but its effective bandwidth is 100 Mbit/s because line coding scheme is NRZI and 4B5B block coding specified in IEEE Standard 802.3. + +## 6.3 Spectral characteristics + +For MLM lasers, the spectral width is specified by the maximum Root-Mean-Square (RMS) width under standard operating conditions. The RMS width means the standard deviation ( $\sigma$ ) of spectral distribution. As to the measurement method for RMS width, all modes should be within 20 dB range from the peak mode. + +For SLM lasers, the maximum spectral width is specified by the maximum full width measured at the point of 20 dB lower than the maximum amplitude of the central wavelength under standard operating conditions. Additionally, for control of mode partition noise in SLM systems, a minimum value for the laser side-mode suppression ratio is specified. + +In this Recommendation, specification for SLM lasers is for future study. + +## 6.4 Mean launched power + +Mean launched power at reference point is the average optical power of a pseudo-random data sequence coupled into the fibre by the transmitter. + +## 6.5 Receiver characteristics + +Receiver characteristics are described as minimum overload and minimum sensitivity as the average optical power against pseudo-random data sequence. Sensitivity includes power penalty. + +## 6.6 Extinction ratio + +The convention adopted for optical logic level is: + +- Emission light for a logical "1"; +- No emission light for a logical "0". + +The extinction ratio (EX) is defined as: + +$$EX = 10 \log_{10}(A/B)$$ + +Where A is the average optical power level for a logical "1" and B is the average optical power level for a logical "0". + +## 6.7 Pulse mask + +Pulse mask at reference points is in conformance with ITU-T Rec. G.957, STM-1. + +Bessel-Thomson filter of fourth-order or fifth-order with cut-off frequency of $125 \text{ MHz} \times 0.75$ shall be used for measuring. Also Bessel-Thomson filter of fourth-order or fifth-order with cut-off frequency of $155.52 \text{ MHz} \times 0.75$ might be used. + +## 6.8 S/X + +The OLT (or ONT) shall receive both signal and cross-talk light from the ONT (or OLT) because of multiple reflections incurred by discontinuity of reflective index on the optical path. The OLT or ONT must have applicable S/X against reflection from the optical path which satisfies the specification of optical return loss. + +Reflection model is assumed to have such a structure that it is connected to two connectors at near end, with optical return loss of 35 dB for one connector and 32 dB for two connectors. + +If the total optical return loss of optical signals transmitted from the OLT (or ONT), which reflects on the optical path and/or at the opposite ONT (or OLT), falls on the value described in Tables 2 and 3, the bit error ratio in Tables 2 and 3 can be satisfied within the range of receiver characteristics in this Recommendation. + +In Tables 2 and 3, minimum optical return loss of the optical path is assumed to be 14 dB because the reflection from two connectors (32 dB) is small enough compared with that from the ONT or OLT (14 dB). + +![Figure 3/G.985 – Reflection model diagram](ea37ab05b033e59cfdf7b074161aaf5a_img.jpg) + +The diagram illustrates a reflection model for an optical path. On the left, a rectangular block labeled "ONT (or OLT)" is connected to a pair of square blocks representing "Connector". A line with an arrow points from the label "Connector" to these two blocks. Following the connectors, a horizontal line with a break (indicated by three dots) represents the optical fiber. At the right end of the fiber, an arrow points to the interface with another rectangular block labeled "OLT (or ONT)". This arrow is labeled "Reflection point at the opposite interface". Below the "OLT (or ONT)" block, the text "G.985\_F03" is present. + +Figure 3/G.985 – Reflection model diagram + +**Figure 3/G.985 – Reflection model** + +## 6.9 Optical return loss of the interface + +The optical return loss of the interface means the ODN reflection of its received light. Therefore, the optical return loss of the interface is defined by the wavelength of 1550 nm band for the ONT, and by the wavelength of 1310 nm band for the OLT. + +## 6.10 Test pattern + +Data pattern to be used in measuring wavelength or spectral characteristics is not specified in this Recommendation, but short continuous random test pattern described in IEEE Standard 802.3, Annex 36A.5 may be referred. + +## 6.11 Jitter + +Jitter is time distortion of optical signal, incurred through the process of electrical-optical conversion at the transmitter or by the effect of optical path. + +Duty distortion shall be specified by pulse mask in this specification, and it is recommended in this clause that the jitter of transmitter excluding duty distortion may be less than 1 ns, and similarly the jitter durability of receiver may be more than 2.5 ns. + +At the receiver, the duty distortion specified in pulse mask may be taken into account as well as jitter durability. + +## 6.12 Signal detect + +Interruption of communication such as release of optical connector or power interruption of the opposite side equipment shall be detected to avoid incorrect link up between OLT and ONT. + +## 6.13 Optical connector + +The formation and characteristic of optical connector, which is connected to the OLT, the ONT and optical fibre of optical path mechanically, is not specified in this Recommendation. + +# 7 Requirements for the OAM + +## 7.1 General requirements + +Ethernet based point-to-point connection is simple to configure, therefore a simple OAM function is required. To provide optical access services using the Ethernet based point-to-point system, the operator should be capable of following actions from the remote side, which are not defined in the Ethernet protocol. To achieve these actions, the OLT should be able to monitor and test the ONT. + +### – *Identification of the failure point* + +The OLT should identify where the failure point is (e.g., in the optical line, inside the ONT and so on). Optical link signal status and ONT status should be monitored by the OLT in order to identify this. And to know the power-off of the ONT, the ONT should also notify its power status to the OLT. + +### – *Verification of the line* + +The loop-back test for the optical access line from the OLT is required. + +The layer for this OAM function is defined as shown in Figure 4. + +Also, performance monitoring items are specified as optional in this Recommendation, which is defined in layer-2 exceptionally. + +![Diagram of the layer structure for OAM functions in an OLT/ONT. The diagram shows two parallel stacks of layers. The left stack (for Medium SMF) consists of: Repeater or higher layer function, RS, MII, OAM sub-layer (highlighted), MII, PCS, PMA, and PMD. The right stack (for Medium UTP) consists of: Repeater or higher layer function, RS, MII, PCS, PMA, and PMD. An arrow points from the text 'Described in this clause' to the OAM sub-layer in the left stack. The entire structure is labeled 'OLT/ONT' at the top right. The diagram is labeled 'G.985_F04' at the bottom right.](bd0b93e7a46ede276d0a3b79ac487bd9_img.jpg) + +Diagram of the layer structure for OAM functions in an OLT/ONT. The diagram shows two parallel stacks of layers. The left stack (for Medium SMF) consists of: Repeater or higher layer function, RS, MII, OAM sub-layer (highlighted), MII, PCS, PMA, and PMD. The right stack (for Medium UTP) consists of: Repeater or higher layer function, RS, MII, PCS, PMA, and PMD. An arrow points from the text 'Described in this clause' to the OAM sub-layer in the left stack. The entire structure is labeled 'OLT/ONT' at the top right. The diagram is labeled 'G.985\_F04' at the bottom right. + +**Figure 4/G.985 – Index of clause 7 in the layer structure** + +## 7.2 Requirements for the OAM functions + +The OAM function is used by OLT to control and monitor the ONT. This protocol allows the OLT to: + +- Request status and information to the ONT. +- Receive alarm from the ONT. +- Start and end loop-back test. + +In this Recommendation, this function is protocol-independent, but its sequences are shown in 7.4. + +### 7.2.1 Fault management + +Fault management provides functions of ONT to notify an alarm to the OLT. The ONT should also notify a recover from these faults to the OLT. + +- *Power supply* +This indicates the power supply fault on the ONT or the power-off of ONT by the end user in order to inhibit the link down alarm on the access line detected at the OLT. +- *ONT failure* +This indicates any failure in ONT. +- *Received signal* +This indicates no valid signal received at ONT receiver in downstream. This can be notified by the FEFI defined in 100BASE-FX of IEEE Standard 802.3. + +### 7.2.2 Loop-back test + +Loop-back test is used by the OLT to check the transportation of the Ethernet frames over the access line. The OLT controls the start and end of loop-back test. This means that the OLT changes following ONT status. + +- *ONT loop-back status* +This indicates the ONT is in the loop-back test mode or in the normal operation mode. + +### **7.2.3 Notification** + +Notification provides function to request the ONT information. This function includes the following items. + +- ONT vender code. +- ONT model number. + +## **7.3 Managed entities** + +The managed entities are as follows. + +### **7.3.1 Loop-back test status** + +This managed entity indicates an ONT status which is the loop-back test mode or the normal operation mode. + +Attributes: + +LoopbackStatusID: This attribute provides the loop-back status of ONT. This includes "during loop-back test" and "normal operation". + +### **7.3.2 ONT product information** + +This managed entity indicates the information related to the ONT. The ONT sends this managed entity to the OLT with attributes of proper values when the OLT requests. + +Attributes: + +ONT\_VenderCode: This attribute provides the vender code of the ONT. + +ONT\_ModelNumber: This attribute provides the model number of the ONT. + +### **7.3.3 Power supply** + +This managed entity indicates the power supply status of the ONT in order to prevent link down alarm on access line from being detected at the OLT. The ONT notifies this managed entity to the OLT with attributes of proper values when its power supply condition changes to the normal status or the power down status. + +Attributes: + +ONT\_PowerSupplyStatusID: This attribute provides the power supply status of the ONT which includes "normal" and "power down". + +### **7.3.4 ONT failure** + +This managed entity indicates the failure of the ONT. The ONT notifies this managed entity to the OLT with attributes of proper values when failure occurs or when it recovers from failure. + +Attributes: + +ONT\_Failure: This attribute provides the any failure status of the ONT. This includes "normal" and "failure". + +### **7.3.5 Received signal** + +This managed entity indicates the status of received signals from the OLT. This is the alarm status that downstream signal does not receive by the ONT. The ONT notifies this managed entity to OLT with attributes of proper values when the ONT detects fault of received signals from the OLT or when the ONT detects recovery of those signals. + +Attributes: + +ReceivedSignalStatusID: This attribute provides the received signal status of the ONT. This includes "normal" and "failure". + +## 7.4 Requirements for the OAM signals and sequences + +To realize the requirements for the OAM, it is necessary to define the following OAM signals and sequences. The OAM signals are defined to transmit information described above and control-commands on the Ethernet connection. The OAM signal should cover upstream and downstream direction. The sequence means the flow of the OAM signal transmission between ONT and OLT. And the sequences are defined to transmit information described above correctly using the OAM signals. + +- a) *OAM signals* + - i) OAM signals should support layer-1-only devices (e.g., a repeater, etc.). Therefore, a special frame is required for the OAM signal, easy to handle layer-1-only devices. + - ii) OAM signals should have the error protection such as CRC. + - iii) OAM signals coming from user/service network side and going to a user/service network side should be prohibited. +- b) *Sequences* + - i) The OLT sends a request signal to the ONT, and the ONT sends a response signal to the OLT for status notification. + - ii) The ONT sends an alarm indication signal to the OLT for fault management. + - iii) The OLT sends a request signal to the ONT in order to start or end the loop-back test, and the ONT sends a response signal to the OLT. + - iv) The OLT sends loop-back frames after it receives a response signal of loop-back start. + +When an OAM signal for loop-back test start or end is lost, the OLT and the ONT should recover to the normal operation mode from loop-back test mode automatically. + +For these sequences, the following signals are defined. + +- a) *Request status and information to the ONT* + - i) Status notification request (from OLT to ONT). + - ii) Status notification response (from ONT to OLT). +- b) *Receive alarm from the ONT* + - i) Status notification trap (from ONT to OLT). +- c) *Control loop-back test start and end* + - i) Loop-back test start request (from OLT to ONT). + - ii) Loop-back test start response (from ONT to OLT). + - iii) Loop-back test end request (from OLT to ONT). + - iv) Loop-back test end response (from ONT to OLT). + - v) Loop-back test end trap (from ONT to OLT for unexpected loop-back end). + +## 7.5 Requirements for the performance monitor function + +In this Recommendation, the performance monitoring function is defined in layer-2 exceptionally because it facilitates traffic monitoring better than if it had been defined in layer-1. + +This function is here also specified as optional, and performance monitoring at the ONT is out of scope in this Recommendation. + +Monitor items at the OLT are shown in the Table 4. + +**Table 4/G.985 – Performance monitor items** + +| Item | Description | +|---------------------------------------|---------------------------------------------------------------------------------------------------------| +| All Packets received from ONT | This indicates a number of all packets received from ONT. | +| Unicast Packets received from ONT | This indicates a number of only unicast packets received from ONT. | +| Non-Unicast Packets received from ONT | This indicates a number of only Non-unicast packets (Multicast or Broadcast packets) received from ONT. | +| Error Packets received from ONT | This indicates a number of error packets (discarded packets) received from ONT. | +| All Packets received from SNI | This indicates a number of all packets received from SNI. | +| Unicast Packets received from SNI | This indicates a number of only unicast packets received from SNI. | +| Non-Unicast Packets received from SNI | This indicates a number of only Non-unicast packets (Multicast or Broadcast packets) received from SNI. | +| Error Packets received from SNI | This indicates a number of error packets (discarded packets) received from SNI. | + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.987.3-202505-I_PDF-E/raw.md b/marked/G/T-REC-G.987.3-202505-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..e08d163876595d3b3637e1aa7705184c244c42f4 --- /dev/null +++ b/marked/G/T-REC-G.987.3-202505-I_PDF-E/raw.md @@ -0,0 +1,4179 @@ + + +# Recommendation + +# **ITU-T G.987.3 (05/2025)** + +SERIES G: Transmission systems and media, digital systems and networks + +Digital sections and digital line system – Optical line systems for local and access networks + +# --- **10-Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification** + +![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font superimposed on the globe. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **Transmission systems and media, digital systems and networks** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100-G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200-G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300-G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400-G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450-G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600-G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700-G.799 | +| DIGITAL NETWORKS | G.800-G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900-G.999 | +| General | G.900-G.909 | +| Parameters for optical fibre cable systems | G.910-G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920-G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930-G.939 | +| Digital line systems provided by FDM transmission bearers | G.940-G.949 | +| Digital line systems | G.950-G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960-G.969 | +| Optical fibre submarine cable systems | G.970-G.979 | +| Optical line systems for local and access networks | G.980-G.989 | +| Metallic access networks | G.990-G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000-G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000-G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000-G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000-G.8999 | +| ACCESS NETWORKS | G.9000-G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.987.3 + +# 10-Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification + +## Summary + +Recommendation ITU-T G.987.3 describes the transmission convergence layer for 10-gigabit-capable passive optical network systems – a family of flexible access network systems that operate over a point-to-multipoint optical access infrastructure at nominal data rates in the order of 10.0 Gbit/s in at least one direction, while providing a wide range of broadband and narrow-band services to end-users. + +The 2025 revision of Recommendation ITU-T G.987.3 builds upon its 2014 revision, as amended in March 2020 and May 2021, implementing the TC layer consistency updates across the ITU-T PON specifications and providing routine maintenance fixes. + +## History\* + +| Edition | Recommendation | Approval | Study Group | Unique ID | +|---------|-----------------------------|------------|-------------|--------------------| +| 1.0 | ITU-T G.987.3 | 2010-10-07 | 15 | 11.1002/1000/10890 | +| 1.1 | ITU-T G.987.3 (2010) Amd. 1 | 2012-06-22 | 15 | 11.1002/1000/11535 | +| 2.0 | ITU-T G.987.3 | 2014-01-13 | 15 | 11.1002/1000/12098 | +| 2.1 | ITU-T G.987.3 (2014) Amd. 1 | 2020-03-15 | 15 | 11.1002/1000/14191 | +| 2.2 | ITU-T G.987.3 (2014) Amd. 2 | 2021-05-29 | 15 | 11.1002/1000/14622 | +| 3.0 | ITU-T G.987.3 | 2025-05-14 | 15 | 11.1002/1000/16337 | + +## Keywords + +10-gigabit PON, optical access network, passive optical network, XGEM, XGTC. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2025 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|-----------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Conventions ..... | 2 | +| 6 | XG-PON transmission convergence layer overview..... | 3 | +| 6.1 | XGTC layer structure ..... | 3 | +| 6.2 | XGTC sublayer functions..... | 4 | +| 6.3 | Management of an XG-PON system..... | 6 | +| 6.4 | Time division multiplexing architecture ..... | 7 | +| 6.5 | Media access control ..... | 10 | +| 7 | Resource allocation and quality of service ..... | 11 | +| 7.1 | Principles of downstream and upstream resource allocation ..... | 11 | +| 7.2 | Dynamic bandwidth assignment overview..... | 13 | +| 7.3 | Reference model of dynamic bandwidth assignment..... | 15 | +| 7.4 | DBA performance requirements..... | 19 | +| 8 | XG-PON transmission convergence layer framing..... | 20 | +| 8.1 | Downstream XGTC framing ..... | 20 | +| 8.2 | Upstream XGTC framing..... | 25 | +| 9 | XG-PON encapsulation method ..... | 27 | +| 9.1 | XGEM framing..... | 27 | +| 9.2 | XGEM frame delineation ..... | 29 | +| 9.3 | SDU fragmentation..... | 29 | +| 9.4 | Mapping of services into XGEM frames..... | 30 | +| 10 | PHY adaptation sublayer ..... | 31 | +| 10.1 | Downstream PHY frame ..... | 31 | +| 10.2 | Upstream PHY frames and upstream PHY bursts..... | 34 | +| 10.3 | Forward error correction..... | 35 | +| 10.4 | Scrambling..... | 39 | +| 11 | PLOAM messaging channel ..... | 39 | +| 11.1 | Overview ..... | 39 | +| 11.2 | PLOAM message format..... | 41 | +| 11.3 | PLOAM message definitions ..... | 42 | +| 12 | ONU activation..... | 52 | +| 12.1 | Overview ..... | 52 | +| 12.2 | Activation mechanism at the ONU..... | 54 | +| 12.3 | OLT support of the activation process ..... | 60 | + +| | Page | | +|---------|-----------------------------------------------------------------------|-----| +| 13 | OLT and ONU timing relationships ..... | 61 | +| 13.1 | ONU transmission timing and equalization delay ..... | 61 | +| 13.2 | Time of day distribution over XG-PON ..... | 68 | +| 14 | Performance monitoring, supervision, and defects..... | 70 | +| 14.1 | Performance monitoring ..... | 71 | +| 14.2 | Defects ..... | 75 | +| 15 | XG-PON security..... | 77 | +| 15.1 | Threat model for XG-PON ..... | 77 | +| 15.2 | Authentication ..... | 77 | +| 15.3 | Key derivation ..... | 80 | +| 15.4 | XGEM payload encryption system ..... | 81 | +| 15.5 | Data encryption key exchange and activation mechanism..... | 83 | +| 15.6 | Integrity protection and data origin verification for PLOAM ..... | 89 | +| 15.7 | Integrity protection and data origin verification for OMCI..... | 90 | +| 15.8 | Integrity and data origin verification key switching..... | 91 | +| 15.9 | XG-PON systems with reduced data encryption strength ..... | 93 | +| 16 | ONU power management ..... | 94 | +| 16.1 | Power management configuration and signalling ..... | 95 | +| 16.2 | Power management parameter definitions ..... | 95 | +| 16.3 | Power management state machine specifications..... | 96 | +| 16.4 | Management transactions during low power mode..... | 103 | +| Annex A | – Hybrid error correction (HEC) decoding and scrambler sequence ..... | 105 | +| A.1 | HEC decoding ..... | 105 | +| A.2 | Scrambler sequence ..... | 107 | +| Annex B | – Forward error correction using shortened Reed-Solomon codes ..... | 109 | +| B.1 | Polynomial representation over Galois field ..... | 109 | +| B.2 | Construction of RS(248, 232) codeword..... | 109 | +| B.3 | Construction of RS(248, 216) codeword..... | 110 | +| Annex C | – Secure mutual authentication via OMCI ..... | 112 | +| Annex D | – Secure mutual authentication based on IEEE 802.1X..... | 113 | +| D.1 | Introduction ..... | 113 | +| D.2 | Stack model for XG-PON authentication using [IEEE 802.1X] ..... | 114 | +| D.3 | Behaviour at network entry ..... | 114 | +| Annex E | – PON-ID maintenance..... | 116 | +| E.1 | Introduction ..... | 116 | +| E.2 | PON-ID structure..... | 116 | +| Annex F | – Extended rogue ONU mitigation capabilities ..... | 118 | +| F.1 | Introduction ..... | 118 | +| F.2 | Extra codepoint of disable PLOAM message type..... | 118 | + +| | Page | +|--------------------------------------------------------------------------------|------| +| F.3 Extra transition of the ONU activation cycle state transition diagram..... | 119 | +| Appendix I – Downstream line data pattern conditioning ..... | 121 | +| I.1 Spectrum control using idle XGEM frames ..... | 121 | +| I.2 Intentional PON disruption..... | 123 | +| Appendix II – Time of day derivation and error analysis ..... | 125 | +| Appendix III – Burst profiles ..... | 128 | +| Appendix IV – Golden vectors ..... | 130 | +| IV.1 Downstream FEC codeword..... | 130 | +| IV.2 Upstream FEC codeword ..... | 130 | +| IV.3 Upstream FEC short codeword ..... | 131 | +| IV.4 Downstream AES-128 encryption..... | 131 | +| IV.5 Upstream AES-128 encryption..... | 132 | +| IV.6 Key derivation encryption ..... | 132 | +| IV.7 Downstream PLOAM message integrity check ..... | 132 | +| IV.8 Upstream PLOAM message integrity check ..... | 133 | +| IV.9 Upstream key reporting ..... | 133 | +| IV.10 Downstream OMCI message integrity check..... | 133 | +| Bibliography..... | 134 | + + + +# Recommendation ITU-T G.987.3 + +# 10-Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification + +# 1 Scope + +This Recommendation describes the transmission convergence layer for 10-Gigabit-capable passive optical network (XG-PON) systems – a family of flexible access network systems that operate over a point-to-multipoint optical access infrastructure at the nominal data rate of 10.0 Gbit/s in at least the downstream direction, while providing a wide range of broadband and narrow-band services to end-users. + +This Recommendation specifies: + +- the layered structure of the XG-PON transmission convergence (XGTC) layer; +- functionality of the service adaptation sublayer, including XG-PON encapsulation method (XGEM), XGEM frame delineation, and service data unit (SDU) fragmentation; +- functionality of the framing sublayer with the specification of the downstream XG-PON frame and upstream burst formats; +- functionality of the physical interface (PHY) adaptation sublayer, including forward error correction and scrambling; +- XG-PON embedded management functionality, including upstream time-division multiple access and dynamic bandwidth assignment mechanisms; +- the XG-PON physical layer operation, administration and management (OAM) messaging channel; +- the optical network unit (ONU) activation method; +- timing aspects of point-to-multipoint operation and time-of-day communication; +- cryptographic mechanisms for authentication, integrity verification, channel isolation and data protection along with and the associated key exchange protocols; +- signalling mechanisms and protocols to support ONU power saving. + +This Recommendation forms an integral part of the [ITU-T G.987] series of ITU-T Recommendations [ITU-T G.987], [ITU-T G.987.1], [ITU-T G.987.2] that, together with [ITU-T G.988], specify a single coherent set of access transmission systems. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +[[ITU-T G.652](#)] Recommendation ITU-T G.652 (2024), *Characteristics of a single-mode optical fibre and cable*. + +[[ITU-T G.709](#)] Recommendation ITU-T G.709/Y.1331 (2020), *Interfaces for the optical transport network*. + +| | | +|------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [ITU-T G.987] | Recommendation ITU-T G.987 (2012), 10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations and acronyms. | +| [ITU-T G.987.1] | Recommendation ITU-T G.987.1 (2016), 10-Gigabit-capable passive optical networks (XG-PON): General requirements. | +| [ITU-T G.987.2] | Recommendation ITU-T G.987.2 (2023), 10-Gigabit-capable passive optical networks (XG-PON): Physical media dependent (PMD) layer specification. | +| [ITU-T G.988] | Recommendation ITU-T G.988 (2022), ONU management and control interface (OMCI) specification. | +| [ITU-T I.432.1] | Recommendation ITU-T I.432.1 (1999), B-ISDN user-network interface – Physical layer specification: General characteristics. | +| [ATIS-0300220] | ATIS-0300220 (2011), Structure for the Representation of the Communications Industry Manufacturers, Suppliers, and Related Service Companies for Information Exchange. | +| [IEEE 802.1X] | IEEE Standard 802.1X (2010), IEEE Standard for Local and metropolitan area networks – Port-Based Network Access Control. | +| [IETF RFC 3748] | IETF RFC 3748 (2004), Extensible Authentication Protocol (EAP). | +| [IETF RFC 5216] | IETF RFC 5216 (2008), The EAP-TLS Authentication Protocol. | +| [IETF RFC 5247] | IETF RFC 5247 (2008), Extensible Authentication Protocol (EAP) Key Management Framework. | +| [IETF RFC 5433] | IETF RFC 5433 (2009), Extensible Authentication Protocol – Generalized Pre-Shared Key (EAP-GPSK) Method. | +| [NIST FIPS-197] | NIST Federal Information Processing Standards Publication 197 (2001), Advanced Encryption Standard (AES). | +| [NIST SP800-38A] | NIST Special Publication 800-38A (2001), Recommendation for Block Cipher Modes of Operation – Methods and Techniques. | +| [NIST SP800-38B] | NIST Special Publication 800-38B (2005), Recommendation for Block Cipher Modes of Operation: The CMAC Mode for Authentication. | + +# 3 Definitions + +See clause 3 of [ITU-T G.987]. + +## 4 Abbreviations and acronyms + +See clause 4 of [ITU-T G.987]. + +# 5 Conventions + +See clause 5 of [ITU-T G.987]. + +# 6 XG-PON transmission convergence layer overview + +## 6.1 XGTC layer structure + +The XGTC layer is a part of the XG-PON protocol stack that specifies the formats and procedures of mapping between upper layer service data units (SDUs), on the one hand, and bitstreams suitable for modulating the optical carrier, on the other hand. + +The XGTC layer is composed of three sublayers: the XGTC service adaptation sublayer, the XGTC framing sublayer, and the XGTC PHY adaptation sublayer. The XGTC layer is present at both the optical line terminal (OLT) and ONU sides of an XG-PON system. In the downstream direction, the interface between the XGTC layer and the physical medium dependent (PMD) layer is represented by a continuous bitstream at the nominal interface rate, which is partitioned into 125 $\mu$ s frames. In the upstream direction, the interface between the XGTC layer and the PMD layer is represented by a sequence of precisely timed bursts. The key transformation stages involved in the mapping between the upper layer SDUs and the PHY bitstream for the downstream and upstream directions are shown in Figures 6-1 and 6-2, respectively. + +![Diagram of downstream SDU mapping showing the flow from SDUs through XGEM, XGTC, and PHY adaptation sublayers to form a 125 microsecond PHY frame.](d26959f4514c26ca19c3d6f00da85956_img.jpg) + +The diagram illustrates the mapping of Service Data Units (SDUs) into a physical frame for downstream transmission. It is divided into three horizontal sections representing different sublayers: + +- Service adaptation sublayer:** At the top, multiple SDUs are shown. Some are mapped directly into XGEM payloads, while others are fragmented into smaller units before being mapped. Each XGEM payload is preceded by a header 'H'. These XGEM frames are then aggregated into a larger XGTC payload. +- Framing sublayer:** The XGTC payload is encapsulated into an XGTC frame, which includes an 'XGTC header'. This frame is then passed to the next sublayer. +- PHY adaptation sublayer:** The XGTC frame is further processed into a physical frame. It is divided into segments, each consisting of 'FEC data' and a parity bit 'P', forming an 'FEC codeword'. These codewords are then scrambled and preceded by a 'PSBd' (Physical Synchronization Burst) to form the final 'Scrambled PHY frame payload'. + +The bottom of the diagram shows two consecutive 'PHY frame, 125 $\mu$ s' units, each starting with a 'PSBd' followed by the 'Scrambled PHY frame payload'. + +H XGEM frame header +P FEC parity + +G.987.3(10)\_F6-1 + +Diagram of downstream SDU mapping showing the flow from SDUs through XGEM, XGTC, and PHY adaptation sublayers to form a 125 microsecond PHY frame. + +**Figure 6-1 – Downstream SDU mapping** + +![Figure 6-2 – Upstream SDU mapping diagram showing the flow of data from Service adaptation sublayer to PHY adaptation sublayer through the Framing sublayer.](d4af765160d04ecef538e5066006dc77_img.jpg) + +The diagram illustrates the upstream SDU mapping process across three sublayers: + +- Service adaptation sublayer:** Accepts SDUs (Service Data Units) from upper layers. It handles SDU fragmentation (indicated by 'SDU fragment\*') and encapsulates them into XGEM frames. Each XGEM frame consists of a header 'H' and a payload. These frames are then aggregated into XGTC payloads. +- Framing sublayer:** Takes the XGTC payloads and encapsulates them into XGTC frames. Each frame includes an 'XGTC header', 'Allocation Overhead (AO)', the 'XGTC payload', and an 'XGTC trailer'. The payload is divided into 'Allocations'. These frames are then burst into 'XGTC bursts'. +- PHY adaptation sublayer:** Takes the XGTC bursts and prepares them for physical transmission. It adds 'FEC parity (P)' to the data to form 'FEC codewords'. A 'PSBu' (Physical Burst Unit) is added to the beginning of the burst. The final output is a 'Scrambled PHY burst payload' which constitutes the 'PHY burst'. + +Figure 6-2 – Upstream SDU mapping diagram showing the flow of data from Service adaptation sublayer to PHY adaptation sublayer through the Framing sublayer. + +(\*) The remaining fragment of the SDU is transmitted in the subsequent allocation with the same Alloc-ID. + +G.987.3(14)-Amd.2(21)\_F6-2 + +H – XGEM frame header + +AO – Allocation overhead + +P – FEC parity + +**Figure 6-2 – Upstream SDU mapping** + +The basic functionality of the three sublayers of the XG-PON TC layer is reviewed in clause 6.2. + +## 6.2 XGTC sublayer functions + +### 6.2.1 XGTC service adaptation sublayer + +The XGTC service adaptation sublayer is responsible for upper layer SDU encapsulation, multiplexing and delineation in the course of transmission over PON. + +On the transmitter side, the XGTC service adaptation sublayer accepts the upper layer SDUs, represented by user data frames and ONU management and control interface (OMCI) traffic, performs SDU fragmentation as necessary, assigns an XGEM Port-ID to an SDU or SDU fragment, and applies to it the XG-PON encapsulation method to obtain an XGEM frame. The XGEM frame payload can be optionally encrypted. A series of XGEM frames forms a payload of an XGTC frame in the downstream direction or an XGTC burst in the upstream direction. + +On the receiver side, the XGTC service adaptation sublayer accepts the payload of the XGTC frames and bursts, performs XGEM frame delineation, filters XGEM frames based on the XGEM Port-IDs, + +decrypts the XGEM payload if encryption has been performed by the transmitter, reassembles the fragmented SDUs, and delivers the SDUs to the respective clients. + +See clauses 9.1, 9.2, and 9.3 for the details of XGEM framing, XGEM frame delineation, and SDU fragmentation, respectively. + +As the service adaptation sublayer deals with two types of SDUs, it can be logically decomposed into an XGEM engine, responsible for XGEM Port-ID multiplexing and filtering, and two service adapters: the user data adapter and the OMCI adapter. The user data adapter can be configured to accommodate a variety of upper layer transport interfaces. + +See clause 9.4 for the most common cases of service mappings into XGEM frames. + +### **6.2.2 XGTC framing sublayer** + +The XGTC framing sublayer is responsible for the construction and parsing of the overhead fields that support the necessary PON management functionality. The frame formats are devised so that the frames and their elements are aligned to 4-byte word boundaries, whenever possible. + +On the transmitter side, the XGTC framing sublayer accepts multiple series of XGEM frames forming the XGTC payload from the XGTC service adaptation sublayer, and constructs the downstream XGTC frame or upstream XGTC burst by providing embedded OAM and physical layer operations, administration and maintenance (PLOAM) messaging channel overhead fields. The size of each downstream XGTC frame payload is obtained by subtracting the variable size of the upstream bandwidth management overhead and the PLOAM channel load from the fixed size of the downstream XGTC frame. In the upstream direction, an XGTC burst multiplexes XGTC payloads associated with multiple Alloc-IDs, the size of each payload being determined based on the incoming bandwidth management information. + +On the receiver side, the XGTC framing sublayer accepts the XGTC frames or XGTC bursts, parses the XGTC overhead fields, extracting the incoming embedded management and PLOAM messaging flows, and delivers the XGTC payloads to the service adaptation sublayer. The incoming PLOAM messaging channel flow is delivered to the PLOAM processing engine. The embedded OAM information to the extent pertaining to upstream bandwidth management (BWmap parsing) and dynamic bandwidth assignment (DBA) signalling is processed within the framing sublayer itself, providing partial controls over the PHY adaptation sublayer (upstream PHY burst timing and profile control), and service adaptation sublayer (encryption key indication). The rest of the embedded OAM information is delivered to the control entities outside of the framing sublayer, such as ONU power management and performance monitoring blocks. + +See clause 8.1 for the details of downstream XGTC frame format specification, including BWmap parsing, and clause 8.2 for the details of upstream XGTC burst format specification, including DBA signalling. + +### **6.2.3 XGTC PHY adaptation sublayer** + +The PHY adaptation sublayer encompasses the functions that modify the bitstream modulating the optical transmitter with the goal to improve the detection, reception and delineation properties of the signal transmitted over the optical medium. + +On the transmitter side, the PHY adaptation sublayer accepts the XGTC frames (in the downstream direction) or XGTC bursts (in the upstream direction) from the XGTC framing sublayer, partitions them into FEC data blocks, computes and appends the FEC parity field to each FEC data block, performs scrambling of the FEC-protected content, prepends the physical synchronization block appropriate for downstream (PSBd) or upstream (PSBu) transmission, and provides timing alignment of the resulting bitstream. + +On the receiver side, the PHY adaptation sublayer performs physical synchronization and delineation of the incoming bitstream, descrambles the content of the PHY frame or burst, executes forward error + +correction and extracts the forward error correction (FEC) parity symbols, delivering the resulting XGTC frames (in the downstream direction) or XGTC bursts (in the upstream direction) to the XGTC framing sublayer. + +The details of the PSBd and PSBu overhead fields are specified in clauses 10.1 and 10.2, respectively. + +The use of FEC improves the effective sensitivity and overload characteristics of the optical receiver by introducing redundancy in the transmitted bitstream and allowing the receiver to operate at a higher bit-error ratio (BER) level. Forward error correction is specified in detail in clause 10.3. + +Bitstream scrambling randomizes the transmission and helps to improve the consecutive identical digit (CID) immunity. The XG-PON scrambling method is specified in clause 10.4. + +Another topic that could formally belong to the scope of the PHY adaptation sublayer is line coding. As specified in [ITU-T G.987.2], the downstream and upstream line code employed in XG-PON1 is non-return to zero (NRZ). This code has unit rate, and is not discussed further in this Recommendation. + +![Figure 6-3 – Outline of XGTC information flow. The diagram shows three sublayers: (1) XGTC PHY adaptation sublayer, (2) XGTC framing sublayer, and (3) XGTC service adaptation sublayer. At the top, 'User data client' and 'OMCI client' connect to 'User data adapter' and 'OMCI adapter' respectively. These adapters connect to an 'XGEM engine'. The 'XGEM engine' connects to the 'XGTC frame/burst' section of the framing sublayer. The framing sublayer contains 'PLOAM partition', 'Embedded header fields', and 'XGEM partition'. Above the framing sublayer is 'Upstream bandwidth mgmt DBA control'. The 'PLOAM processor' in the service adaptation sublayer connects to 'XGTC functions: PM, Security key mgmt, ONU power mgmt', which in turn connects to the 'Embedded header fields'. The 'PLOAM processor' also connects to the 'PLOAM partition'. The 'PHY burst timing and profile control' in the PHY adaptation sublayer connects to the 'PLOAM partition' and 'XGEM partition'.](a26e142d3df5bef41a84a9dd099d7825_img.jpg) + +(1) XGTC PHY adaptation sublayer +(2) XGTC framing sublayer +(3) XGTC service adaptation sublayer + +G.987.3(10)\_F6-3 + +Figure 6-3 – Outline of XGTC information flow. The diagram shows three sublayers: (1) XGTC PHY adaptation sublayer, (2) XGTC framing sublayer, and (3) XGTC service adaptation sublayer. At the top, 'User data client' and 'OMCI client' connect to 'User data adapter' and 'OMCI adapter' respectively. These adapters connect to an 'XGEM engine'. The 'XGEM engine' connects to the 'XGTC frame/burst' section of the framing sublayer. The framing sublayer contains 'PLOAM partition', 'Embedded header fields', and 'XGEM partition'. Above the framing sublayer is 'Upstream bandwidth mgmt DBA control'. The 'PLOAM processor' in the service adaptation sublayer connects to 'XGTC functions: PM, Security key mgmt, ONU power mgmt', which in turn connects to the 'Embedded header fields'. The 'PLOAM processor' also connects to the 'PLOAM partition'. The 'PHY burst timing and profile control' in the PHY adaptation sublayer connects to the 'PLOAM partition' and 'XGEM partition'. + +**Figure 6-3 – Outline of XGTC information flow** + +## 6.3 Management of an XG-PON system + +The control, operation, and management information in an XG-PON system is carried over three channels: embedded OAM, PLOAM and OMCI. The embedded OAM and PLOAM channels manage the functions of the PMD and XGTC layers. OMCI provides a uniform system for managing higher (service-defining) layers. + +### 6.3.1 Embedded OAM + +The embedded OAM channel is provided by well-defined header fields and embedded structures of the downstream XGTC frame and upstream XGTC burst. This channel offers a low-latency path for the time-urgent control information because each information piece is directly mapped into a specific field. The functions that use this channel include: upstream PHY burst timing and profile control, bandwidth allocation, data encryption key selection, dynamic bandwidth assignment signalling, + +forced wake-up, and dying gasp indication. The detailed description of the header fields and structures involved in support of these functions is provided in clause 8 as a part of the XGTC framing sublayer specification. + +### 6.3.2 PLOAM channel + +The PLOAM channel is message based and is carried in a dedicated space of the downstream XGTC frame and upstream XGTC burst. This channel is used for all PMD and XGTC management information that is not sent via the embedded OAM channel. The PLOAM message structure, message types and detailed format specifications are provided in clause 11. + +### 6.3.3 ONU management and control interface (OMCI) + +The ONU management and control interface (OMCI) channel (OMCC) is used to manage the service-defining layers that reside above the XGTC, and is technically out of the scope of this Recommendation. However, the XGTC layer must provide an XGEM-based transport interface for this management traffic, including configuration of appropriate transport protocol flow identifiers (XGEM Port-IDs). This Recommendation specifies a format and transfer mechanism for the OMCI channel. The detailed OMCI specification can be found in [ITU-T G.988]. + +The OMCI adapter at the ONU is responsible for filtering and de-encapsulating OMCI-carrying XGEM frames in the downstream direction, and encapsulating OMCI SDUs in the upstream direction. OMCI SDUs are handed off to the logic that implements the OMCI functions. + +The OMCI adapter at the OLT is responsible for filtering and de-encapsulating OMCI-carrying XGEM frames in the upstream direction and for encapsulating OMCI SDUs from the OMCI control logic into XGEM frames for transport to the ONU. + +## 6.4 Time division multiplexing architecture + +### 6.4.1 Overview + +In the downstream direction, the traffic multiplexing functionality is centralized. The OLT multiplexes XGEM frames onto the transmission medium using XGEM Port-ID as a key to identify XGEM frames that belong to different downstream logical connections. Each ONU filters the downstream XGEM frames based on their XGEM Port-IDs and processes only the XGEM frames that belong to that ONU. Multicast XGEM port can be used to carry XGEM frames to more than one ONU. + +![Diagram illustrating downstream multiplexing in XG-PON. An OLT (Optical Line Terminal) is shown on the left, connected to three ONUs (Optical Network Units) on the right via a PON (Passive Optical Network). The OLT has eight XGEM ports, each connected to one of the ONUs. The diagram shows the OLT multiplexing traffic from its ports onto the PON, which then splits to the ONUs. The caption below the diagram reads 'G.987.3(10)_F6-4'.](70de8885bd7de15723aaad5eb5c5febf_img.jpg) + +G.987.3(10)\_F6-4 + +Diagram illustrating downstream multiplexing in XG-PON. An OLT (Optical Line Terminal) is shown on the left, connected to three ONUs (Optical Network Units) on the right via a PON (Passive Optical Network). The OLT has eight XGEM ports, each connected to one of the ONUs. The diagram shows the OLT multiplexing traffic from its ports onto the PON, which then splits to the ONUs. The caption below the diagram reads 'G.987.3(10)\_F6-4'. + +Figure 6-4 – Downstream multiplexing in XG-PON + +In the upstream direction, the traffic multiplexing functionality is distributed. The OLT grants upstream transmission opportunities, or upstream bandwidth allocations, to the traffic-bearing entities within the subtending ONUs. The ONU's traffic-bearing entities that are recipients of the upstream bandwidth allocations are identified by their allocation IDs (Alloc-IDs). Bandwidth allocations to different Alloc-IDs are multiplexed in time as specified by the OLT in the bandwidth maps transmitted downstream. Within each bandwidth allocation, the ONU uses the XGEM Port-ID as a multiplexing key to identify the XGEM frames that belong to different upstream logical connections. + +![Diagram of upstream multiplexing in XG-PON. It shows an OLT on the left connected to two ONUs on the right via a PON. The OLT has three 'Alloc-ID' blocks. Each 'Alloc-ID' block is connected to three 'XGEM port' blocks. Each 'XGEM port' block is connected to one of the two ONUs. The diagram illustrates how traffic from different Alloc-IDs is multiplexed at the OLT and then distributed to the ONUs via XGEM ports. The label 'G.987.3(10)_F6-5' is at the bottom right.](5cab96b2d23174c25919840ecd50aa48_img.jpg) + +Diagram of upstream multiplexing in XG-PON. It shows an OLT on the left connected to two ONUs on the right via a PON. The OLT has three 'Alloc-ID' blocks. Each 'Alloc-ID' block is connected to three 'XGEM port' blocks. Each 'XGEM port' block is connected to one of the two ONUs. The diagram illustrates how traffic from different Alloc-IDs is multiplexed at the OLT and then distributed to the ONUs via XGEM ports. The label 'G.987.3(10)\_F6-5' is at the bottom right. + +**Figure 6-5 – Upstream multiplexing in XG-PON** + +### 6.4.2 ONU identifier + +The ONU-ID is a 10-bit identifier that the OLT assigns to an ONU during the ONU's activation using the PLOAM messaging channel. + +The ONU-ID is unique across the PON. When an ONU enters the initial state (O1) of the ONU activation state machine (see clause 12 for the causes of the possible state transitions to O1), it discards the previously assigned ONU-ID along with all dependent XGTC layer configuration assignments. + +Table 6-1 presents the semantics of the ONU-ID values. + +**Table 6-1 – ONU-ID values** + +| ONU-ID | Designation | Comment | +|---------|----------------------|------------------------------------------------------------------------------------------------------------------------------------------------| +| 0..1022 | Assignable | Assigned by OLT at ONU activation; used to identify the sender of an upstream burst or a PLOAMu message and the recipient of a PLOAMd message. | +| 1023 | Broadcast/unassigned | Broadcast address in PLOAMd; unassigned ONU in PLOAMu. | + +### 6.4.3 Allocation identifier (Alloc-ID) + +The allocation identifier (Alloc-ID) is a 14-bit number that the OLT assigns to an ONU to identify a traffic-bearing entity that is a recipient of upstream bandwidth allocations within that ONU. Such a traffic-bearing entity can be represented either by a transmission container (T-CONT) or by the upstream OMCC. + +Each ONU is assigned one or more Alloc\_IDs including at least the default Alloc-ID. The ONU's default Alloc-ID is numerically equal to its ONU-ID, and is assigned implicitly, by virtue of the ONU-ID assignment at ONU activation. The default Alloc-ID carries the upstream OMCC traffic and may + +carry user data traffic. The default Alloc-ID is also used for PLOAM-only allocations to a specific ONU. The default Alloc-ID cannot be de-allocated or changed throughout the duration of the ONU activation cycle (i.e., until the ONU is re-activated and reassigned a new ONU-ID). + +Additional Alloc-IDs are assigned at the OLT's discretion explicitly by means of the Assign\_Alloc-ID PLOAM message with Alloc-ID type 1 (see clause 11.3.3.7 for the Assign\_Alloc-ID PLOAM message definition). Additional Alloc-IDs are used to carry user data traffic. Their assignment can be explicitly reversed by means of the Assign\_Alloc-ID PLOAM message with Alloc-ID type 255. + +An Alloc-ID is unique for a given PON and can be assigned to at most one ONU. When an ONU enters the initial state (O1) of the ONU activation state machine (see clause 12 for the causes of the possible state transitions to O1), it discards all Alloc-ID assignments, including the default Alloc-ID assignment. + +The semantics of the Alloc-ID values is shown in Table 6-2. + +**Table 6-2 – Alloc-ID values** + +| Alloc-ID | Designation | Comment | +|-------------|-------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0..1022 | Default | Default Alloc-ID, which is implicitly assigned with and is equal to the ONU-ID. | +| 1023 | Broadcast | Used by OLT in a serial number grant allocation structure to indicate that any ONU executing the serial number acquisition phase of the activation procedure may use this allocation to transmit a serial number response. | +| 1024..16383 | Assignable | If more than a single Alloc-ID is needed for an ONU, the OLT assigns additional Alloc-IDs to that ONU by selecting a unique number from this range and communicating it to the ONU using the Assign_Alloc-ID PLOAM message. | + +### 6.4.4 XGEM port identifier + +The XGEM port identifier, or XGEM Port-ID, is a 16-bit number that is assigned by the OLT to an individual logical connection. The XGEM Port-ID assignment to the OMCC logical connection is implicit by virtue of the ONU-ID assignment to the given ONU. The OMCC Port-ID is numerically equal to the respective ONU-ID. All other XGEM Port-ID assignments for the ONU are performed via the OMCC. + +When an ONU enters the initial state (O1) of the ONU activation state machine (see clause 12 for the causes of the possible state transitions to O1), it discards the default XGEM Port-ID assignment, but retains the previously assigned non-default XGEM Port-IDs. + +The semantics of the XGEM Port-ID values is shown in Table 6-3. + +**Table 6-3 – XGEM Port-ID values** + +| XGEM Port-ID | Designation | Comment | +|--------------|-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0..1022 | Default | Default XGEM Port-ID, which is implicitly assigned with and is equal to the ONU-ID; it is used to transport the OMCC traffic. | +| 1023..65534 | Assignable | If more than a single XGEM Port-ID is needed for an ONU, the OLT assigns additional Port-IDs to that ONU by selecting a unique number from this range and communicating it to the ONU using the OMCI management channel. | +| 65535 | Idle | Reserved for Idle XGEM Port-ID | + +## 6.5 Media access control + +In an XG-PON system, the OLT provides media access control for the upstream traffic. In the basic concept, each downstream PHY frame contains a bandwidth map (BWmap) that indicates the location for upstream transmissions by various ONUs in the corresponding upstream PHY frame. The media access control concept in an XG-PON system is illustrated in Figure 6-6. + +The OLT transmits a downstream PHY frame every 125 $\mu\text{s}$ . Because of the varying fibre distance, each given PHY frame reaches different ONUs at generally different time instants. With each received downstream PHY frame, an ONU associates the corresponding upstream PHY frame. The individual equalization delays established in the course of ONU ranging (see clause 12) serve to align the ONU views on the start of each upstream PHY frame in such a way that upstream transmissions by any two ONUs, occurring at a fixed offset with respect to the start of the upstream PHY frame, would reach the OLT at precisely the same instant. + +For each PHY frame, the OLT creates and transmits downstream a BWmap that specifies a sequence of non-overlapping upstream transmissions by different ONUs. A BWmap contains a number of allocation structures, each allocation structure being addressed to a particular Alloc-ID of a specific ONU. A sequence of one or more allocation structures addressed to Alloc-IDs that belong to the same ONU forms a burst allocation series. Each burst allocation series contains a start pointer indicating the beginning of the burst within the upstream PHY frame and a sequence of grant sizes that the ONU is allowed to transmit. The start pointers refer to offsets within the upstream PHY frame (on the PHY adaptation sublayer), whereas the grant sizes pertain to the payload of XGTC frame (on the framing sublayer). The start pointers and grant sizes are expressed in units of words (one word equals 4 bytes). A single word allocation per PHY frame corresponds to an instantaneous data rate of 256 kbit/s. The OLT may grant higher or lower effective data rates by controlling the size and frequency of the grants and may modulate the effective data rate via a dynamic scheduling. + +![Diagram illustrating the XGTC media access control concept. It shows the OLT transmitting a Downstream PHY frame containing a BWmap. The BWmap is a table with columns for Alloc ID, Start time, and Grant size. The OLT uses this map to schedule upstream transmissions for ONUs X and Y. The Upstream PHY frame shows bursts of data from ONU X (Alloc-ID X and Alloc-ID 1050) and ONU Y (Alloc-ID Y).](9b9d2abd741ed4bafe7f78f89961c663_img.jpg) + +| Alloc ID | Start time | Grant size | Alloc ID | Start time | Grant size | Alloc ID | Start time | Grant size | +|----------|------------|------------|----------|------------|------------|----------|------------|------------| +| Y | • | • | X | • | • | 1050 | ☒ | • | + +G.987.3(10)\_F6-6 + +Diagram illustrating the XGTC media access control concept. It shows the OLT transmitting a Downstream PHY frame containing a BWmap. The BWmap is a table with columns for Alloc ID, Start time, and Grant size. The OLT uses this map to schedule upstream transmissions for ONUs X and Y. The Upstream PHY frame shows bursts of data from ONU X (Alloc-ID X and Alloc-ID 1050) and ONU Y (Alloc-ID Y). + +Figure 6-6 – XGTC media access control concept + +The use of BWmap parameters is discussed more precisely in clause 8.1.2. The details of the PON timing relationships can be found in clause 13. + +# 7 Resource allocation and quality of service + +Access-specific quality of service (QoS) capabilities are an integral part of the end-to-end QoS provisioning mechanisms. They are necessary, but they are not sufficient to ensure that the QoS objectives of end-to-end traffic flows are met. In an XG-PON-based optical access network, QoS capabilities are supported by the OLT and ONU network elements and are associated with the ways and means to allocate available resources, including processing capacity, buffer space, and digital bandwidth of communication links, to individual traffic flows and traffic flow aggregates. + +## 7.1 Principles of downstream and upstream resource allocation + +A traffic flow is provisioned with a specific set of downstream and upstream service parameters. These parameters may be represented by a traffic descriptor. + +### 7.1.1 Forms of traffic descriptor + +In its conventional form, the traffic descriptor is composed of the bandwidth parameters and is generally represented as: + +$$D = \langle R_F, R_A, R_M, \chi_{AB}, P, \omega \rangle \quad (7-1)$$ + +where: + +$R_F$ : Fixed bandwidth [bit/s]; + +$R_A$ : Assured bandwidth [bit/s]; + +$R_M$ : Maximum bandwidth [bit/s]; + +$\chi_{AB}$ : Ternary eligibility indicator for additional bandwidth assignment: {none, non-assured (NA), best-effort (BE)}; + +$P$ : Priority for best-effort bandwidth assignment; + +$\omega$ : Weight for best-effort bandwidth assignment. + +**Fixed bandwidth**, $R_F \geq 0$ , represents the reserved portion of the link capacity that is allocated to the given traffic flow, regardless of its traffic demand and the overall traffic load conditions. + +**Assured bandwidth**, $R_A \geq 0$ , represents a portion of the link capacity that is allocated to the given traffic flow as long as the flow has unsatisfied traffic demand, regardless of the overall traffic conditions. + +**Maximum bandwidth**, $R_M > 0$ , represents the upper limit on the total bandwidth that can be allocated to the traffic flow under any traffic conditions. + +In its extended form, the traffic descriptor is composed of the bandwidth parameters and the timing parameters and is represented as: + +$$D = \langle R_F, R_A, R_M, \chi_{AB}, P, \omega, T_{JT}, T_{BDT} \rangle \quad (7-1a)$$ + +where, additionally: + +**Jitter tolerance**, $T_{JT} > 0$ , represents the minimum time interval over which an active traffic flow shall receive an allocation of the size corresponding at least to the assigned bandwidth. + +**Bandwidth assignment delay tolerance**, $T_{BDT} > 0$ , represents the maximum delay that a previously inactive traffic flow may experience from the moment it becomes active to the moment it receives an allocation of the size corresponding at least to the assigned bandwidth. + +The implementations predating the present amendment are not required to support the extended form of the traffic descriptor. For the subsequent implementations, the support of the extended form of the traffic descriptor is subject to operator requirements. The implementations not supporting the + +extended form of the traffic descriptor are expected to have well understood default values or bounds of the timing parameters, based on the system design. + +### 7.1.2 Traffic descriptor constraints + +A correctly formed traffic descriptor should satisfy the following three invariant restrictions: + +$$R_M \geq R_F + R_A$$ + +$$\text{if } \chi_{AB} = NA, \text{ then } R_M > R_F + R_A > 0 \quad (7-2)$$ + +$$\text{if } \chi_{AB} = BE, \text{ then } R_M > R_F + R_A \geq 0$$ + +In addition, the overall traffic specification should satisfy the basic stability condition: + +$$\sum_i (R_F^i + R_A^i) \leq C \quad (7-3)$$ + +where the summation is over the set of all upstream or downstream traffic flows on the PON, and $C$ is the capacity of the upstream or downstream interface, respectively. + +The specified general form of traffic descriptor allows support of both rate-based service disciplines and priority-based service disciplines. By setting certain descriptor components to zero (rate parameters) or identical values (priority and weight parameters), the system operator can effectively specify the required service discipline. The upstream and downstream traffic flows may be specified with different subsets of descriptor components. In particular, the fixed bandwidth parameter is important in a distributed scheduling environment, where it serves to mitigate the communication latency between the network elements hosting, respectively, the scheduler and the traffic queues, and may not be applicable in the downstream direction where scheduling is centralized. + +If necessary, two or more traffic flows may be considered as a single aggregate flow. The traffic descriptor of the aggregate flow is constructed by the system from the individual traffic descriptors of the constituent traffic flows. The rate parameters of the aggregate flow traffic descriptor (denoted by an asterisk) are expected to satisfy: + +$$\begin{aligned} R_F^* + R_A^* &= \sum_j (R_F^j + R_A^j) \\ \max_j R_M^j &\leq R_M^* \leq \sum_j R_M^j \end{aligned} \quad (7-4)$$ + +where the superscript $j$ denotes a parameter of the $j$ th constituent traffic descriptor. Determination of the parameter values of the aggregate flow traffic descriptor from its constituent traffic descriptors is beyond the scope of this Recommendation. + +In the downstream direction, it is the responsibility of the OLT to provide QoS-aware traffic management (including, as applicable, buffer management, traffic scheduling and shaping) of XGEM Port-ID traffic flows based on the respective traffic descriptors, availability of memory and bandwidth resources, and dynamic traffic conditions. Because this function is internal to the OLT, it is beyond the scope of this Recommendation. + +In the upstream direction, an aggregate traffic descriptor is constructed for each transmission container (T-CONT) based on the service specifications of the XGEM Port-ID flows multiplexed onto that T-CONT. It is the responsibility of the OLT to provide QoS-aware traffic management of the aggregate traffic flows associated with the T-CONTs based on the respective aggregate service specifications, the upstream bandwidth availability and, possibly, the information obtained through upstream traffic monitoring and/or ONU status reporting. For each individual T-CONT, it is the responsibility of the ONU to which the T-CONT belongs to provide QoS-aware traffic management + +of the constituent XGEM Port-ID traffic flows based on the respective XGEM Port-ID service specifications, resource availability, and dynamic traffic conditions. + +The ONU upstream traffic management facilities supporting resource allocation and QoS may include ingress traffic policing, traffic shaping, XGEM Port-ID flow scheduling within a T-CONT. The specification of these functions is beyond the scope of this Recommendation. + +The remainder of this clause is concerned specifically with the upstream traffic management, and any reference to provisioned traffic parameters pertains to aggregate traffic descriptors associated with Alloc-IDs. + +## 7.2 Dynamic bandwidth assignment overview + +Dynamic bandwidth assignment (DBA) in XG-PON is the process by which the OLT allocates upstream transmission opportunities to the traffic-bearing entities within ONUs, based on dynamic indication of their activity and their configured traffic contracts. The activity status indication can be either explicit through buffer status reporting, or implicit through transmission of idle XGEM frames during the upstream transmission opportunities. + +In comparison with static bandwidth assignment, the DBA mechanism improves XG-PON upstream bandwidth utilization by reacting adaptively to the ONUs' burst traffic patterns. The practical benefits of DBA are twofold. First, the network operator can add more subscribers to the access network due to more efficient bandwidth use. Second, subscribers can enjoy enhanced services, such as those requiring variable rate with peaks extending beyond the levels that can reasonably be allocated statically. + +### 7.2.1 PON DBA abstraction + +In XG-PON, the recipient entity of the upstream bandwidth allocation is represented by an allocation ID (Alloc-ID). Regardless of the number of Alloc-IDs assigned to each ONU, the number of XGEM ports multiplexed onto each Alloc-ID, and the actual physical and logical queuing structure implemented by the ONU, the OLT models the traffic aggregate associated with each Alloc-ID as a single logical buffer and, for the purpose of bandwidth assignment, considers all Alloc-IDs specified for the given PON to be independent peer entities on the same level of logical hierarchy. + +![Diagram illustrating the PON DBA abstraction. It shows multiple ONUs (ONU 1 to ONU N) connected to an OLT. Each ONU contains multiple logical buffers (Alloc-ID A, C, X, Z) represented by yellow rectangles. Dashed lines labeled 'BWmap' connect these buffers to a 'DBA' block within the OLT, indicating the flow of bandwidth allocation information.](75e4b78ee25f885d73120e3066a5253e_img.jpg) + +The diagram illustrates the PON DBA abstraction. On the left, there are two ONUs, labeled ONU 1 and ONU N. Each ONU contains multiple logical buffers, represented by yellow rectangles, labeled with Alloc-IDs: Alloc-ID A, Alloc-ID C for ONU 1, and Alloc-ID X, Alloc-ID Z for ONU N. Dashed lines labeled 'BWmap' connect these buffers to a 'DBA' block within the OLT on the right. The OLT contains a 'DBA' block, which is connected to the ONUs via the 'BWmap' lines. The diagram is labeled G.987.3(10)\_F7-1. + +Diagram illustrating the PON DBA abstraction. It shows multiple ONUs (ONU 1 to ONU N) connected to an OLT. Each ONU contains multiple logical buffers (Alloc-ID A, C, X, Z) represented by yellow rectangles. Dashed lines labeled 'BWmap' connect these buffers to a 'DBA' block within the OLT, indicating the flow of bandwidth allocation information. + +Figure 7-1 – PON DBA abstraction + +For each Alloc-ID logical buffer, the DBA functional module of the OLT infers its occupancy either by collecting inband status reports, or by observing the upstream idle pattern, or both. The DBA + +function then provides input to the OLT upstream scheduler, which is responsible for generating the bandwidth maps (BWmaps). The BWmap specifies the size and timing of upstream transmission opportunities for each Alloc-ID, and is communicated to the ONUs inband with the downstream traffic. + +### 7.2.2 DBA functional requirements + +Dynamic bandwidth assignment in XG-PON encompasses the following functions. These functions apply on the level of individual Alloc-IDs and their provisioned bandwidth component parameters: + +- 1) Inference of the logical upstream transmit buffer occupancy status. +- 2) Update of the instantaneously assigned bandwidth according to the inferred buffer occupancy status within the provisioned bandwidth component parameters. +- 3) Issue of allocations according to the updated instantaneous bandwidth. +- 4) Management of the DBA operations. + +The XG-PON OLT is required to support DBA. + +### 7.2.3 DBA methods + +Depending on the ONU buffer occupancy inference mechanism, two DBA methods can be distinguished: + +- status reporting (SR) DBA is based on explicit buffer occupancy reports that are solicited by the OLT and submitted by the ONUs in response; +- traffic monitoring (TM) DBA is based on the OLT's observation of the idle XGEM frame pattern and its comparison with the corresponding bandwidth maps; +- cooperative (CO) DBA is based on the application-level upstream scheduling information provided by the OLT-side external equipment, such as a BBU in a wireless transport system. + +The XG-PON OLT shall support a combination of both TM and SR DBA methods and may additionally support the CO DBA method. The XG-PON OLT CT shall be capable of performing the DBA functions of clause 7.2.2 in an efficient and fair manner. The specific efficiency and fairness criteria can be based on overall PON utilization, the individual ONU's performance, tested against the corresponding objectives, and comparative performance tested for multiple ONUs. + +An XG-PON ONU shall support DBA status reporting, and shall transmit upstream DBA reports as instructed by the OLT. The status reporting DBA method involves in-band signalling between the OLT and the ONUs, which is an inherent part of the XGTC specification. Status reporting DBA signalling is discussed in detail in clause 8.2.2. + +Unlike SR and TM methods, the CO DBA does not require any upstream grant allocation for upstream status reporting or activity testing. + +The algorithmic details of how the OLT applies the reported or inferred status information, the entire specification of the traffic monitoring DBA method, as well as the details of the OLT upstream scheduler, which is responsible for the BWmap generation, are outside the XGTC layer scope, and their implementation is left to the OLT vendor. + +### 7.2.4 DBA engine + +The unified conceptual representation of the DBA engine is shown in Figure 7-1*bis*. + +![Figure 7-1bis – DBA engine conceptual representation. The diagram shows the internal components of a DBA engine. On the left, 'Cooperative DBA (modulating T-CONT descriptor parameters over time)' is indicated by a bracket. This bracket encompasses two input groups: 'T-CONT descriptor rate parameters: R_F, R_A, R_M' and 'T-CONT descriptor timing parameters: T_JT, T_DBT'. Both groups point to a 'DBA engine' block. Inside the DBA engine, the first group points to a 'Bandwidth assignment' block, and the second group points to a 'BWmap generation' block. The 'Bandwidth assignment' block outputs 'Assigned bandwidths per T_DBT' to the 'BWmap generation' block. The 'BWmap generation' block also receives an 'OAM' input from below and produces a 'BWmap per 125 μs' output to the right. To the right of the DBA engine, a dashed box labeled 'See Clause 7.3' contains 'T-CONT activity indication (dynamic): Status reporting' and 'Traffic monitoring'. Arrows from these two items point into the 'Bandwidth assignment' block. A reference code 'G.987.3(14)-Amd.1(20)_F7-1bis' is at the bottom right.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg) + +Figure 7-1bis – DBA engine conceptual representation. The diagram shows the internal components of a DBA engine. On the left, 'Cooperative DBA (modulating T-CONT descriptor parameters over time)' is indicated by a bracket. This bracket encompasses two input groups: 'T-CONT descriptor rate parameters: R\_F, R\_A, R\_M' and 'T-CONT descriptor timing parameters: T\_JT, T\_DBT'. Both groups point to a 'DBA engine' block. Inside the DBA engine, the first group points to a 'Bandwidth assignment' block, and the second group points to a 'BWmap generation' block. The 'Bandwidth assignment' block outputs 'Assigned bandwidths per T\_DBT' to the 'BWmap generation' block. The 'BWmap generation' block also receives an 'OAM' input from below and produces a 'BWmap per 125 μs' output to the right. To the right of the DBA engine, a dashed box labeled 'See Clause 7.3' contains 'T-CONT activity indication (dynamic): Status reporting' and 'Traffic monitoring'. Arrows from these two items point into the 'Bandwidth assignment' block. A reference code 'G.987.3(14)-Amd.1(20)\_F7-1bis' is at the bottom right. + +**Figure 7-1bis – DBA engine conceptual representation** + +The DBA engine consists of the fair bandwidth assignment and BWmap generation components. The fair bandwidth assignment component uses the rate parameters of T-CONT traffic descriptors along with the dynamic indication of the traffic load obtained through ONU status reporting (SR) and upstream traffic monitoring (TM) to compute a set of assigned bandwidths. The assigned bandwidth calculation is repeated every DBA cycle according to the reference model discussed in clause 7.3. The assigned bandwidths are then supplied to the BWmap generator component, which uses them, along with the timing parameters of T-CONT traffic descriptors and the local OAM input, to generate a BWmap once every 125 μs. + +If the DBA engine obtains the dynamic traffic load information exclusively via the fibre interface using the SR and TM methods, the traffic descriptor parameters remain static. If in addition the DBA engine uses the cooperative interface (CO) method, the application-level upstream scheduling information from the OLT-side external equipment is applied to modulate the rate and timing parameters of traffic descriptors over time, effectively making them dynamic. + +## 7.3 Reference model of dynamic bandwidth assignment + +### 7.3.1 Summary of notation + +The following additional notation is employed throughout this clause: + +- $A$ The amount of traffic arriving to a buffer [bit]. +- $B$ Logical buffer occupancy [bit]. +- $R$ Total assigned bandwidth, dynamic [bit/s]. +- $R_G$ Assigned guaranteed bandwidth, dynamic [bit/s]. +- $R_L$ Offered traffic load, dynamic [bit/s]. +- $R_{NA}$ Assigned non-assured bandwidth, dynamic [bit/s]. +- $R_{BE}$ Assigned best-effort bandwidth, dynamic [bit/s]. + +$S_{NA}$ Surplus bandwidth available for non-assured assignment, dynamic [bit/s]. + +$S_{BE}$ Surplus bandwidth available for best-effort assignment, dynamic [bit/s]. + +Where appropriate, a superscript indicates a specific Alloc-ID. + +### 7.3.2 Offered traffic load + +Each Alloc-ID can be dynamically characterized by its offered traffic load, $R_L(t)$ , which is defined as the average rate at which the logical buffer of an Alloc-ID would have to be served in order to be drained in certain fixed time $\Delta$ , representing a system constant (equal to at least one, but more practically, eight-frame times): + +$$R_L(t) = \frac{B(t) + A(t, t + \Delta)}{\Delta} \quad (7-5)$$ + +where $B(t)$ is the logical buffer occupancy at time $t$ , and the optional term $A(t, t + \Delta)$ represents new arrivals to the buffer during the interval $(t, t + \Delta)$ . Note that $A(t, t + \Delta)$ may be excluded from the definition if strictly non-predictive reference is desired. + +### 7.3.3 Components of assigned bandwidth + +The bandwidth $R^i(t) \geq 0$ , dynamically assigned to Alloc-ID $i$ under the present reference model, is composed of the guaranteed and additional components (see Figure 7-2). The guaranteed bandwidth, $R_G^i(t)$ , can be in the form of fixed bandwidth and assured bandwidth. The additional bandwidth can be either in non-assured form, $R_{NA}^i(t)$ , or best-effort form, $R_{BE}^i(t)$ : + +$$R^i(t) = R_G^i(t) + R_{NA}^i(t) \quad (7-6a)$$ + +for Alloc-IDs $i$ with $\chi_{AB}^i = \text{NA}$ , + +$$R^i(t) = R_G^i(t) + R_{BE}^i(t) \quad (7-6b)$$ + +for Alloc-IDs $i$ with $\chi_{AB}^i = \text{BE}$ , + +$$R^i(t) = R_G^i(t) \quad (7-6c)$$ + +for Alloc-IDs $i$ with $\chi_{AB}^i = \text{None}$ . + +For the guaranteed bandwidth assignment, the reference model employs a criterion based on the provisioned rate parameters. The fixed portion of the guaranteed bandwidth is assigned statically. The assured portion of the guaranteed bandwidth is assigned dynamically based on the offered load of the specific Alloc-ID. For the additional bandwidth assignment, the reference model supports both a rate-proportional criterion and a criterion based on provisioned priority and weights. The additional bandwidth is assigned dynamically (within the shaded area of Figure 7-2) based on the offered load of the specific Alloc-ID and the overall traffic conditions. + +The reference model effectively introduces a strict priority hierarchy among the forms of assigned bandwidth: + +- 1) Fixed bandwidth (highest priority). +- 2) Assured bandwidth. +- 3) Non-assured bandwidth. +- 4) Best-effort bandwidth (lowest priority). + +First, the OLT should assign the fixed bandwidth to all Alloc-IDs on the PON, regardless of their individual offered loads and the overall traffic conditions. Then the OLT completes the guaranteed bandwidth component assignment by allocating assured bandwidth to each Alloc-ID until either the respective provisioned level $R_A$ is reached or the traffic demand is satisfied. After that, the OLT allocates non-assured bandwidth components to the eligible unsaturated Alloc-IDs until either all the + +Alloc-IDs reach their saturation level (that is, the lesser of the respective maximum bandwidth $R_M$ and offered load $R_L(t)$ ), or the surplus bandwidth pool $S_{NA}(t)$ is exhausted. Finally, the OLT allocates best-effort bandwidth components to the eligible unsaturated Alloc-IDs. + +The reference model requires that, for all Alloc-ID $i$ , at all times when the offered traffic load $R_L^i(t)$ exceeds the provisioned fixed level $R_F^i$ , the assigned bandwidth $R^i(t)$ should satisfy the conservation condition: + +$$R^i(t) \leq \min\{R_M^i; R_L^i(t)\} \quad (7-7)$$ + +### 7.3.4 Guaranteed bandwidth assignment + +As long as the basic stability condition of Equation (7-3) is satisfied, the guaranteed component of the dynamically assigned bandwidth is given by: + +$$R_G^i(t) = \min\{R_F^i + R_A^i; \max\{R_F^i; R_L^i(t)\}\} \quad (7-8)$$ + +$R_G^i(t)$ is available to the given Alloc-ID regardless of the overall traffic load conditions. Thus, $R_F^i$ is the lower bound on assigned guaranteed bandwidth $R_G^i(t)$ , and $R_A^i + R_F^i$ is the upper bound. + +![Figure 7-2: Assigned bandwidth components with respect to offered load. The graph plots Assigned bandwidth, R(t) on the y-axis against Offered load, R_L(t) on the x-axis. The y-axis has labels R_F, R_A+R_F, and R_M. The x-axis has labels R_F, R_A+R_F, and R_M. A diagonal line represents the saturation level. The area under the diagonal line is shaded gray. The area above the diagonal line is labeled 'Additional'. The area between R_F and R_A+R_F is labeled 'Assured'. The area between R_A+R_F and R_M is labeled 'Guaranteed'. The area between R_F and R_A+R_F is labeled 'Fixed'. The label 'G.987.3(10)_F7-2' is at the bottom right.](cd31d0e7e4b524e074808154dd279205_img.jpg) + +Figure 7-2: Assigned bandwidth components with respect to offered load. The graph plots Assigned bandwidth, R(t) on the y-axis against Offered load, R\_L(t) on the x-axis. The y-axis has labels R\_F, R\_A+R\_F, and R\_M. The x-axis has labels R\_F, R\_A+R\_F, and R\_M. A diagonal line represents the saturation level. The area under the diagonal line is shaded gray. The area above the diagonal line is labeled 'Additional'. The area between R\_F and R\_A+R\_F is labeled 'Assured'. The area between R\_A+R\_F and R\_M is labeled 'Guaranteed'. The area between R\_F and R\_A+R\_F is labeled 'Fixed'. The label 'G.987.3(10)\_F7-2' is at the bottom right. + +Figure 7-2 – Assigned bandwidth components with respect to offered load + +### 7.3.5 Rate-proportional assignment of additional bandwidth + +To realize the rate-proportional assignment of the additional bandwidth, the Alloc-IDs are provisioned with appropriate individual $R_F^i$ , $R_A^i$ and $R_M^i$ parameters. The priority and weight parameters for all Alloc-IDs are set to identical values. The additional bandwidth eligibility can be provisions to either value (NA, BE, none). + +**Non-assured bandwidth**, $R_{NA}$ , is a form of additional bandwidth that the OLT may dynamically assign to an eligible Alloc-ID in proportion to the sum of that Alloc-ID's fixed and assured bandwidths. + +The amount of surplus bandwidth that can participate in the non-assured bandwidth assignment is equal to the portion of the uplink capacity that remains available after the guaranteed bandwidth components have been dynamically assigned for all Alloc-IDs. This amount is given by the following expression: + +$$S_{NA}(t) = C - \sum_i R_G^i(t) \quad (7-9)$$ + +where $R_G^i(t)$ is specified by Equation (7-8). + +The surplus bandwidth $S_{NA}(t)$ is shared among the eligible ( $\chi_{AB} = \text{NA}$ ) Alloc-IDs so that: + +- 1) the bandwidth conservation condition (7-7) holds, and either +- 2.1) for each Alloc-ID $i$ , the assigned bandwidth satisfies the saturation criterion: + +$$R^i(t) = \min \left\{ R_M^i; \max \left\{ R_L^i(t); R_F^i \right\} \right\} \quad (7-10)$$ + +or + +- 2.2) $S_{NA}(t)$ is exhausted and at most one Alloc-ID remains unsaturated, or +- 2.3) $S_{NA}(t)$ is exhausted and for any two eligible unsaturated Alloc-IDs $i$ and $j$ , the assigned non-assured bandwidths satisfy the fairness condition: + +$$\frac{R_{NA}^i(t)}{R_F^i + R_A^i} = \frac{R_{NA}^j(t)}{R_F^j + R_A^j} \quad (7-11)$$ + +**Best-effort bandwidth** is a form of additional bandwidth that the OLT may dynamically assign to an eligible Alloc-ID in proportion to the non-guaranteed portion of that Alloc-ID's provisioned maximum bandwidth. + +The Alloc-IDs eligible for the best-effort assignment receive additional bandwidth only if all the Alloc-IDs eligible for the non-assured assignment have been saturated. The amount of surplus bandwidth that can participate in the best-effort bandwidth assignment is equal to the portion of the uplink capacity that remains available after all the Alloc-IDs eligible for the non-assured bandwidth assignment have been saturated, and all the other Alloc-IDs have been assigned their respective guaranteed bandwidth components. This amount is given by the following expression: + +$$S_{BE}(t) = C - \sum_{i \in \{\chi_{AB}^i = \text{NA}\}} R^i(t) - \sum_{i \in \{\chi_{AB}^i \neq \text{NA}\}} R_G^i(t) \quad (7-12)$$ + +Here $R_G^i(t)$ is specified by Equation (7-8), and $R^i(t)$ by the saturation criterion (7-10). + +The surplus bandwidth $S_{BE}(t)$ is shared among the eligible ( $\chi_{AB} = \text{BE}$ ) Alloc-IDs so that: + +- 1) the bandwidth conservation condition of Equation (7-7) holds, and either +- 2.1) for each Alloc-ID $i$ , the assigned bandwidth satisfies the saturation criterion of Equation (7-10), or: +- 2.2) $S_{BE}(t)$ is exhausted and at most one Alloc-ID remains unsaturated, or +- 2.3) $S_{BE}(t)$ is exhausted and for any two eligible unsaturated Alloc-IDs $i$ and $j$ , the assigned best-effort bandwidths satisfy the fairness condition: + +$$\frac{R_{BE}^i(t)}{R_M^i - (R_F^i + R_A^i)} = \frac{R_{BE}^j(t)}{R_M^j - (R_F^j + R_A^j)} \quad (7-13)$$ + +### 7.3.6 Additional bandwidth assignment based on priority and weights + +To realize the additional bandwidth assignment based on priority and weights, the Alloc-IDs are provisioned with appropriate individual $P_i$ and $\omega_i$ parameters. The bandwidth parameters for all Alloc-IDs within each $P_i$ level are set to identical values. The additional bandwidth eligibility can be provisions to either BE or none. + +The amount of surplus bandwidth that can participate in the best-effort bandwidth assignment is equal to the portion of the uplink capacity that remains available after the guaranteed bandwidth components have been dynamically assigned for all Alloc-IDs. This amount is given by the following expression: + +$$S_{BE}(t) = C - \sum_i R_G^i(t) \quad (7-14)$$ + +where $R_G^i(t)$ is specified by Equation (7-8). + +The surplus bandwidth $S_{BE}(t)$ is shared among the eligible ( $\chi_{AB} = \text{BE}$ ) Alloc-IDs so that: + +- 1) the bandwidth conservation condition of Equation (7-7) holds, and either + - 2.1) for each Alloc-ID $i$ , the assigned bandwidth satisfies the saturation criterion of Equation (7-10), or + - 2.2) $S_{BE}(t)$ is exhausted and the following two statements hold: + - as long as at least one eligible Alloc-ID $i$ with provisioned priority level $P_i$ remains unsaturated, the assigned best-effort bandwidth share of any Alloc-ID with a logically lower provisioned priority level is zero; + - as long as two eligible Alloc-IDs $i$ and $j$ with identical provisioned priority levels $P_i = P_j$ remain unsaturated, their assigned best-effort bandwidth shares satisfy the fairness condition: + +$$\frac{R_{BE}^i(t)}{\omega_i} = \frac{R_{BE}^j(t)}{\omega_j}. \quad (7-15)$$ + +### 7.3.7 Timing control of assigned bandwidth + +The optional timing parameters of the extended traffic descriptor access network operators to control the temporal aspect of the process that allocates transmission opportunities to the traffic flows based on the assigned bandwidth, thus improving throughput and facilitating support of the delay/jitter-sensitive applications. + +Once the assigned bandwidth of a traffic flow is obtained using the rate-based model, the jitter tolerance parameter, $T_{JT}$ , effectively determines the frequency of grant allocation to the given flow. For the traffic flows that are not sensitive to delay and jitter, the larger $T_{JT}$ stipulates fewer bursts and reduces losses to the burst mode overhead. For the delay/jitter sensitive applications, the shorter $T_{JT}$ increases the frequency of burst allocations, reducing delay and jitter at the expense of diminished overall upstream throughput due to the extra burst mode overhead. The resulting trade-off is subject to evaluation by the operator. + +The bandwidth assignment delay tolerance parameter, $T_{BDT}$ , effectively determines the frequency of grant allocation to a traffic flow that has shown zero or low offered load in the upstream direction. Such grants are needed to execute status reporting and traffic monitoring DBA methods. + +The implementations are expected to support timing parameter configurability based on a finite set of representative values, rather than on a continuous value range. + +## 7.4 DBA performance requirements + +In practice, the OLT DBA algorithm does not have complete knowledge of the system state. In particular, instead of the true offered loads $R_L^i(t)$ , it operates on the basis of estimates, $\hat{R}_L^i(t)$ , which are obtained from the DBRu reports and traffic monitoring results by methods outside the scope of this Recommendation. This clause recommends several DBA performance criteria that allow to evaluate a practical DBA implementation against the reference model of clause 7.3. + +### 7.4.1 Stationary bandwidth assignment + +#### *Definition* + +In a system where Alloc-ID activity and traffic demand status remain constant, the assigned bandwidth to an Alloc-ID is measured as an average over the BWmaps transmitted in any sequence + +of K consecutive downstream frames, where K is chosen large enough to average the allocations that may vary from frame to frame. + +#### *Target performance* + +The OLT DBA algorithm should ensure that the stationary assigned bandwidth for each subtending unsaturated Alloc-ID is at least equal to the respective fixed plus assured bandwidth and is within specified bounds (e.g., 10%) of the dynamic value computed, based on the reference model of clause 7.3. + +### **7.4.2 Assured bandwidth restoration time** + +#### *Definition* + +This is the worst-case time interval, as observed at the ONU, from the moment an Alloc-ID, which is entitled to receive assured bandwidth assignment but has not been receiving it due to insufficient traffic demand, increases the traffic demand to at least its fixed plus assured level, to the moment it is granted the full provisioned assured bandwidth in addition to the fixed bandwidth. The ending moment of the interval is more precisely defined as the start of the first upstream frame in a sequence of K consecutive frames, sufficiently large to average the frame-to-frame variations, over which the average bandwidth allocated to the Alloc-ID meets the specified condition. + +#### *Target performance* + +A few milliseconds is expected (target of 2 ms). + +### **7.4.3 DBA convergence time** + +#### *Definition* + +This is the worst-case time interval from the moment of a single activity status or traffic load change event at any ONU in a previously stationary system, to the moment the OLT adjusts its bandwidth assignments for all the subtending unsaturated ONUs to the levels that are at least equal to the respective fixed plus assured bandwidths, and are within specified bounds (e.g., 20%) of the respective dynamic values computed based on the reference model of clause 7.3. The ending moment of the interval is more precisely defined as the start of the first downstream frame in a sequence of K consecutive frames, sufficiently large to average the frame-to-frame variations, in which the transmitted BWmaps contain bandwidth allocations satisfying the specified condition on average. + +#### *Target performance* + +Ten milliseconds is expected (target of 6 ms). + +# **8 XG-PON transmission convergence layer framing** + +This clause specifies the structure of the downstream XGTC frame and upstream XGTC burst along with the format of the downstream XGTC frame header, upstream XGTC burst header, and upstream XGTC burst trailer. + +## **8.1 Downstream XGTC framing** + +The downstream XGTC frame has the fixed size of 135432 bytes and consists of the XGTC header and the XGTC payload section, as shown in Figure 8-1. The XGTC payload is formed on the transmit side and is processed on the receive side by the service adaptation sublayer. + +The downstream XGTC frame header consists of a fixed size HLEnd structure and two variable size partitions: the bandwidth map partition (BWmap) and downstream PLOAM partition (PLOAMd). + +![Figure 8-1: Downstream XGTC frame format and header fields. The diagram shows a hierarchical breakdown of the frame. At the top level is the 'Downstream XGTC frame, 135432 bytes', which is divided into 'XGTC header' and 'XGTC payload'. The 'XGTC header' is further divided into 'HLend', 'BWmap', and 'PLOAMd'. The 'HLend' field is then expanded into three sub-fields: 'BWmap length' (11 bits), 'PLOAM count' (8 bits), and 'HEC' (13 bits).](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg) + +G.987.3(10)\_F8-1 + +Figure 8-1: Downstream XGTC frame format and header fields. The diagram shows a hierarchical breakdown of the frame. At the top level is the 'Downstream XGTC frame, 135432 bytes', which is divided into 'XGTC header' and 'XGTC payload'. The 'XGTC header' is further divided into 'HLend', 'BWmap', and 'PLOAMd'. The 'HLend' field is then expanded into three sub-fields: 'BWmap length' (11 bits), 'PLOAM count' (8 bits), and 'HEC' (13 bits). + +**Figure 8-1 – Downstream XGTC frame format and header fields** + +### 8.1.1 HLEnd structure + +HLEnd is a 4-byte structure that controls the size of the variable length partitions within the XGTC header. It consists of three fields: + +BWmap length [11 bits]: contains an unsigned integer, N, indicating the number of allocation structures in the BWmap partition. + +PLOAM count [8 bits]: contains an unsigned integer, P, indicating the number of PLOAM messages in the PLOAMd partition. + +Hybrid error correction (HEC) [13 bits]: an error detection and correction field for the HLEnd structure, which is a combination of a truncated BCH(63,12,2) code operating on the 31 initial bits of the HLEnd structure and a single parity bit. The details of the HEC construction and verification are specified in Annex A. + +### 8.1.2 BWmap partition + +The BWmap is a series of 8-byte allocation structures. The number of allocation structures in BWmap is given in the BWmap length field of the HLEnd structure. The actual length of the BWmap partition is $8 \times N$ bytes. + +Each allocation structure specifies a bandwidth allocation to a particular Alloc-ID. A sequence of one or more allocation structures that are associated with the Alloc-IDs that belong to the same ONU and are intended for contiguous upstream transmission form a burst allocation series. The formats of the BWmap partition and an allocation structure are shown in Figure 8-2. The fields of the allocation structure are further explained in the following clauses. + +![Figure 8-2: BWmap partition and the format of an allocation structure. The diagram shows a hierarchical breakdown. The top level is 'BWmap N * 8 bytes', which is composed of 'Allocation structure 1' (8 bytes), 'Allocation structure 2' (8 bytes), an ellipsis, and 'Allocation structure N' (8 bytes). 'Allocation structure 1' is expanded to show its internal fields: 'Alloc-ID' (14 bits), 'Flags' (2 bits), 'StartTime' (16 bits), 'GrantSize' (16 bits), 'FWI' (1 bit), 'Burst Profile' (2 bits), and 'HEC' (13 bits). The 'Flags' field is further expanded into 'DBRu' (1 bit) and 'PLOAMu' (1 bit).](84e5b251aa38db522f76f5cc3afcb853_img.jpg) + +G.987.3(10)\_F8-2 + +Figure 8-2: BWmap partition and the format of an allocation structure. The diagram shows a hierarchical breakdown. The top level is 'BWmap N \* 8 bytes', which is composed of 'Allocation structure 1' (8 bytes), 'Allocation structure 2' (8 bytes), an ellipsis, and 'Allocation structure N' (8 bytes). 'Allocation structure 1' is expanded to show its internal fields: 'Alloc-ID' (14 bits), 'Flags' (2 bits), 'StartTime' (16 bits), 'GrantSize' (16 bits), 'FWI' (1 bit), 'Burst Profile' (2 bits), and 'HEC' (13 bits). The 'Flags' field is further expanded into 'DBRu' (1 bit) and 'PLOAMu' (1 bit). + +**Figure 8-2 – BWmap partition and the format of an allocation structure** + +#### 8.1.2.1 Alloc-ID field + +The allocation ID field contains the 14-bit number that indicates the recipient of the bandwidth allocation, i.e., a particular T-CONT or an upstream OMCC within an ONU. Alloc-ID values and conventions are specified in clause 6.4.3. + +#### 8.1.2.2 Flags field + +The 2-bit Flags field that contains two separate indicators: + +- DBRu: If this bit is set, the ONU should send the DBRu report for the given Alloc-ID. If the bit is not set, the DBRu report is not transmitted. +- PLOAMu: If this bit is set in the first allocation structure of a burst allocation series (as indicated by StartTime field – see clause 8.1.2.3), the size of the upstream XGTC burst header should be 52 bytes, and the ONU should transmit a PLOAM message as a part of the XGTC burst header. If in the first allocation structure of an upstream burst, the PLOAMu bit is not set, the size of the upstream XGTC burst header should be 4 bytes, and the PLOAM message should not be transmitted. For all subsequent allocation structures of the same burst, the PLOAMu flag should be set to 0 by the transmitter and ignored by the receiver. See clause 8.2.1 for the details of the upstream XGTC burst header. + +#### 8.1.2.3 StartTime field + +The StartTime field contains a 16-bit number that indicates the location of the first byte of the upstream XGTC burst within the upstream PHY frame. StartTime is measured from the beginning of the upstream PHY frame and has a granularity of 1 word (4 bytes). The value of StartTime = 0 corresponds to the first word of the upstream PHY frame; the value of StartTime = 9719 corresponds to the last word of the upstream PHY frame. + +In each burst allocation series, only the first allocation carries a specific StartTime value. All the remaining allocation structures of the burst allocation series carry the StartTime value of 0xFFFF. + +Figure 8-3 provides interpretation of StartTime and GrantSize parameters. + +![Diagram illustrating the interpretation of StartTime and GrantSize parameters in an upstream PHY frame. The diagram shows the structure of an XGTC burst within a PHY frame. The PHY frame contains a PSBu (Preamble and Synchronization) followed by FEC-protected data. The XGTC burst is shown as a sequence of XGTC header, Allocation A, Allocation B, and XGTC trailer. GrantSize A and GrantSize B are indicated above the allocations. The StartTime is measured from the start of the upstream PHY frame to the beginning of the XGTC burst. The diagram is labeled G.987.3(10)_F8-3.](7fe7bcb3d40736e0b29d9f48ff3cc026_img.jpg) + +The diagram illustrates the timing and structure of an upstream burst. At the bottom, a horizontal line represents the 'Start of upstream PHY frame'. A vertical arrow points from this start to the beginning of a 'PSBu' block. Another vertical arrow points from the end of the 'PSBu' block to the start of the 'XGTC burst' block. The time interval between these two arrows is labeled 'StartTime'. The 'XGTC burst' block is shown above a dashed line representing the 'Framing sublayer / PHY adaptation sublayer'. Above the dashed line, the 'XGTC burst' is expanded into its components: 'XGTC header', 'Allocation A', 'Allocation B', and 'XGTC trailer'. Above 'Allocation A' is a double-headed arrow labeled 'GrantSize A'. Above 'Allocation B' is a double-headed arrow labeled 'GrantSize B'. The 'FEC-protected data' block is shown below the dashed line, starting after the 'PSBu' and continuing to the right. The label 'G.987.3(10)\_F8-3' is in the bottom right corner. + +Diagram illustrating the interpretation of StartTime and GrantSize parameters in an upstream PHY frame. The diagram shows the structure of an XGTC burst within a PHY frame. The PHY frame contains a PSBu (Preamble and Synchronization) followed by FEC-protected data. The XGTC burst is shown as a sequence of XGTC header, Allocation A, Allocation B, and XGTC trailer. GrantSize A and GrantSize B are indicated above the allocations. The StartTime is measured from the start of the upstream PHY frame to the beginning of the XGTC burst. The diagram is labeled G.987.3(10)\_F8-3. + +**Figure 8-3 – Interpretation of StartTime and GrantSize parameters** + +Note that the start of upstream PHY frame is just a reference point that is not associated with any externally observable event (unlike the start of the downstream PHY frame which is bound to transmission or receipt of the first bit of the PSync sequence). Note further that the OLT and each ONU associate the start of upstream PHY frame with generally different moments in time. See clause 13 for the details of the PON timing relationships. + +#### 8.1.2.4 GrantSize field + +The GrantSize field contains the 16-bit number that indicates the combined length of the XGTC payload data with DBRu overhead transmitted within the given allocation. (Notably, GrantSize does not include XGTC header, XGTC trailer, or FEC overhead.) GrantSize has the granularity of 1 word (4 bytes). The value of GrantSize is equal to zero for the PLOAM-only grants, including serial number grants and ranging grants used in the process of ONU activation. The minimum possible non-zero value of GrantSize is 1, which corresponds to as single word (4 byte) allocation for a DBRu-only transmission. The minimum allocation for XGTC payload proper (DBRu flag not set) is 4 words (16 bytes), in which case GrantSize = 4. + +#### 8.1.2.5 Forced wake-up indication (FWI) bit + +When addressing an ONU that supports the protocol-based power management, the OLT sets the FWI bit to expedite waking up an ONU that has been in a low power mode. See clause 16 for the details of the ONU power management. When required by the OLT power management state machine, the FWI bit is set in the first allocation structure of each burst allocation series to a given ONU. The value of the FWI bit in the subsequent allocations structures of a burst allocation series is not controlled and is ignored by the ONU. + +#### 8.1.2.6 BurstProfile field + +The BurstProfile field is a 2-bit field that contains the index of the burst profile to be used by the PHY adaptation sublayer of the ONU to form the PHY burst. This index refers to the set of valid burst profiles that is communicated to the ONUs by the broadcast or unicast transmissions over the PLOAM messaging channel. For each specified profile, the index is explicitly defined in the profile PLOAM message (see clause 11.3.3.1). + +#### 8.1.2.7 HEC field + +The error detection and correction field for the allocation structure is a combination of a BCH(63, 12, 2) code operating on the 63 initial bits of the allocation structure and a single parity bit. The details of the HEC construction and verification are specified in Annex A. + +### 8.1.3 BWmap construction limitations and parsing rules + +#### 8.1.3.1 BWmap construction limitations + +The OLT uses BWmap partition to allocate upstream transmission opportunities to the ONUs and the individual Alloc-IDs within each ONU. The frequency and size of allocations to each ONU and each Alloc-ID depends on the respective service parameters and the current power management mode of each given ONU. By design, each BWmap partition may contain at most 2047 allocation structures. There are, however, additional restrictions that the OLT should meet while constructing the BWmap in every PHY frame: + +- 1) The OLT is required to specify the multiple distinct burst allocation series in the BWmap in the ascending order of their StartTime values. +- 2) The spacing of adjacent bursts in a BWmap and between the consecutive BWmaps should satisfy the requirements of clause 10.2. +- 3) The minimum StartTime value is zero. This requirement implies that the PSBu portion of an upstream PHY burst can technically belong to the previous PHY frame. +- 4) The maximum StartTime value is 9719. This requirement implies that an ONU burst can cross the PHY frame boundary. +- 5) The maximum number of allocation structures per BWmap is 512. +- 6) The maximum number of allocation structures per a burst allocation series is 16. +- 7) The maximum number of allocation structures per given ONU in a BWmap is 64. + +- 8) The maximum number of burst allocation series per given ONU in a BWmap is 16. +- 9) The maximum allocation size = 9718 words. +- 10) The maximum XGTC burst size = 9720 words. + +The maximum XGTC burst size has been set not to exceed the size of a PHY frame (38880 bytes, or 9720 words). Taking into consideration the size of the fixed XGTC overhead (4 bytes XGTC header without PLOAMu field and 4 bytes XGTC trailer), the largest theoretically possible GrantSize value is 9718. If PLOAMu field is present, the GrantSize can be at most 9706. + +Allocating of either consecutive or closely spaced PHY bursts to the same ONU is not necessary and is not a recommended practice. As a guidance, the OLT may maintain the spacing between bursts allocated to the same ONU equal to at least as much as would be required for two bursts allocated to the different ONUs plus an extra processing margin of 512 bytes. + +With regard to rule 8, it is conceivable that the OLT may face ONUs compliant with an earlier version of this Recommendation. The OLT can discover the ONU's capability by allocating more than 4 burst allocation series per BWmap and observing the ONU's response. + +It is a responsibility of the OLT to ensure that the ONU can handle the number and proximity of bursts being allocated. + +Note that the maximum number of burst allocation series per a BWmap is not a relevant design parameter and hence is not mandated here. + +#### 8.1.3.2 BWmap parsing exceptions + +In general, the ONU should handle any uncorrectable, errored, or dubious BWmap entries in such a way as to minimize the probability of upstream collision, suppressing transmission whenever necessary. The following specific cases apply: + +- If the ONU detects an uncorrectable bit error within an allocation structure, it should suppress transmission for the remainder of the burst. +- If the ONU detects a violation of rule 4 of clause 8.1.3.1, it should not transmit a burst. +- If the ONU detects a violation of rules 5 to 10 of clause 8.1.3.1, it should cut the transmission short as if the respective BWmap construction rules were satisfied. +- If the ONU detects that it is allocated two or more consecutive or closely spaced bursts that the ONU cannot properly process, it should not transmit the subsequent burst or bursts. +- If the ONU detects an unknown Alloc-ID within its burst allocation series, it should suppress transmission of the remainder of the burst. +- If the ONU detects its own Alloc-ID within a burst series of another ONU, it should ignore the condition and should not attempt to transmit. + +### 8.1.4 PLOAMd partition + +The PLOAMd partition contains zero, one or more PLOAM messages. The length of each PLOAM message is 48 bytes. The number of PLOAM messages in the PLOAMd partition is given by the PLOAM count field of the HLend structure. The actual length of the PLOAMd partition is $48 \times P$ bytes. + +The PLOAM message format and the constraints on the PLOAM messaging channel are specified in clause 11. + +Figure 8-4 shows downstream PLOAM partition. + +![Figure 8-4: Downstream PLOAM partition diagram. A top-level box labeled 'PLOAMd P * 48 bytes' branches down to a sequence of boxes: 'PLOAM Message 1 48 bytes', 'PLOAM Message 2 48 bytes', '...', and 'PLOAM Message P 48 bytes'. The diagram is labeled G.987.3(10)_F8-4.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +Figure 8-4: Downstream PLOAM partition diagram. A top-level box labeled 'PLOAMd P \* 48 bytes' branches down to a sequence of boxes: 'PLOAM Message 1 48 bytes', 'PLOAM Message 2 48 bytes', '...', and 'PLOAM Message P 48 bytes'. The diagram is labeled G.987.3(10)\_F8-4. + +**Figure 8-4 – Downstream PLOAM partition** + +## 8.2 Upstream XGTC framing + +In the upstream direction, the interface between the XGTC framing sublayer and XGTC PHY adaptation sublayer is represented by an upstream XGTC burst. The upstream XGTC burst transmitted by a given ONU has a dynamically determined size and consists of the upstream XGTC burst header, one or more bandwidth allocation intervals, each being associated with a specific Alloc-ID, and the XGTC trailer, as shown in Figure 8-5. The size of each allocation interval is dictated by a specific allocation structure of the BWmap. + +Each bandwidth allocation interval contains the XGTC payload section and may contain the allocation overhead that precedes the XGTC payload. The XGTC payload is formed on the transmit side and is processed on the receive side by the corresponding service adaptation sublayer entity (see clause 9.1.1 for discussion of XGTC payload). + +![Figure 8-5: Upstream XGTC burst format and overhead fields diagram. The main sequence is: XGTC header, DBRu, XGTC payload, DBRu, XGTC payload, XGTC trailer. Above the second DBRu is an 'Allocation' box containing 'BufOcc 3 bytes' and 'CRC 1 byte'. Below the XGTC header is a breakdown: ONU-ID (10 bits), Ind (9 bits), HEC (13 bits), and PLOAMu (0 or 48 bytes). Below the XGTC trailer is a 'BIP 4 bytes' box. The diagram is labeled G.987.3(10)_F8-5.](5478f70a6cef3e5672b2b22d28830cfb_img.jpg) + +Figure 8-5: Upstream XGTC burst format and overhead fields diagram. The main sequence is: XGTC header, DBRu, XGTC payload, DBRu, XGTC payload, XGTC trailer. Above the second DBRu is an 'Allocation' box containing 'BufOcc 3 bytes' and 'CRC 1 byte'. Below the XGTC header is a breakdown: ONU-ID (10 bits), Ind (9 bits), HEC (13 bits), and PLOAMu (0 or 48 bytes). Below the XGTC trailer is a 'BIP 4 bytes' box. The diagram is labeled G.987.3(10)\_F8-5. + +**Figure 8-5 – Upstream XGTC burst format and overhead fields** + +### 8.2.1 Upstream XGTC burst header + +The XGTC header includes a 4-byte fixed section and a non-fixed section. The fixed section consists of ONU-ID, Ind, and HEC. The non-fixed section has either zero bytes or a 48-byte PLOAM message, depending on the value of the PLOAMu flag of the corresponding BWmap allocation structure. + +#### 8.2.1.1 ONU-ID field + +The ONU-ID field is a 10-bit field that contains the unique ONU-ID of the ONU that is transmitting the burst. The ONU-ID is assigned to the ONU during the activation process. The OLT can check this field against the BWmap in effect to confirm that the correct ONU is transmitting. + +If the ONU which has not been assigned ONU-ID responds to a broadcast service node (SN) Request allocation in order to announce its presence on the PON, it shall use the value 0x03FF in place of the ONU-ID in the XGTC burst header. + +#### 8.2.1.2 Ind field + +The Ind field has 9 bits that provide fast unsolicited signalling of the ONU status and are allocated as follows: + +- Bit 8 (MSB): **PLOAM queue status**: When set, this bit provides an indication that the ONU's queue of pending upstream PLOAM messages remains non-empty after the current burst is + +transmitted. If this bit is not set, no additional upstream PLOAMu messages are awaiting transmission. + +- Bits 7 – 1: Reserved. +- Bit 0 (LSB): Dying gasp (DG). When this bit is set, it indicates that the ONU has detected a local condition that may prevent the ONU from responding to upstream bandwidth allocations. This indication may assist the OLT in distinguishing fibre plant problems from premises issues. Sending a DG indication does not necessarily constitute a commitment or intent on the part of ONU to turn off transmitter. If the condition that has led to DG indication does not persist, the ONU revokes the indication and continues regular operation. The OLT should not interpret the DG indication by itself as the grounds to withdraw bandwidth allocations to the given ONU. + +#### 8.2.1.3 HEC field + +The error detection and correction field for the upstream XGTC header is a combination of a truncated BCH(63, 12, 2) code operating on the 31 initial bits of the header and a single parity bit. The details of the HEC construction and verification are specified in Annex A. + +#### 8.2.1.4 Upstream PLOAM (PLOAMu) field + +If present, the PLOAMu field contain exactly one PLOAM message. The presence of the PLOAM message is controlled by the OLT with the PLOAMu flag of the first allocation structure in the burst allocation series. The PLOAM message length is 48 bytes. The PLOAM message format is given in clause 11. + +### 8.2.2 Allocation overhead + +If present, the allocation overhead is composed of the DBRu structure. The presence of the DBRu is controlled by the OLT with the DBRu flag of the corresponding allocation structure within the BWmap. The 4-byte DBRu structure carries a buffer status report which is associated with a specific Alloc-ID. + +#### 8.2.2.1 BufOcc field + +The buffer occupancy (BufOcc) field is 3 bytes long and contains the total amount of SDU traffic, expressed in units of 4-byte words, aggregated across all the buffers associated with the Alloc-ID to which the given allocation has been provided. If an individual SDU has the length $L$ bytes, its contribution $W$ towards the reported buffer occupancy is computed as: + +$$W = \begin{cases} \left\lceil \frac{L}{4} \right\rceil, & \text{if } L > 8 \\ 2, & \text{if } 0 < L \leq 8 \end{cases} \quad (8-1)$$ + +The reported value should represent the best available estimate that corresponds to the moment of time when the report is transmitted, that is, to the start of the upstream allocation interval. The reported value should be inclusive of any traffic that may have been scheduled for upstream transmission within this allocation interval. + +While the length $L$ of an individual SDU is a natural number, the BufOcc field needs to encode two special values: 0x000000 denotes an empty buffer, and 0xFFFFF represents an invalid measurement. + +#### 8.2.2.2 CRC field + +The DBRu structure is protected using a CRC-8, using the same polynomial as in [ITU-T I.432.1] ( $g(x) = x^8 + x^2 + x + 1$ ). Unlike [ITU-T I.432.1], however, the CRC is not exclusive OR'ed with 0x55. The receiver of the DBRu field implements the error detecting and correcting functions of the CRC-8. + +If the CRC-8 indicates that an uncorrectable error has occurred, then the information in the DBRu is discarded. + +### 8.2.3 Upstream XGTC burst trailer + +The upstream XGTC burst trailer contains a 4-byte wide bit-interleaved even parity (BIP) field computed over the entire XGTC burst. The OLT receiver verifies the BIP to estimate the BER on the upstream optical link. Note that the BIP-based BER estimate is applicable only when the FEC is turned off. Whenever upstream FEC is turned on in the PHY adaptation sublayer, the raw BER estimate should instead be obtained based on the FEC correction results. + +# 9 XG-PON encapsulation method + +In an XG-PON system, the SDUs, which include the user data frames and high-level PON management frames (OMCI), are transmitted in the XGTC payload sections of the downstream XGTC frames and upstream XGTC bursts using the XG-PON encapsulation method (XGEM). The XGEM supports SDU fragmentation, encapsulation, and delineation, and is applicable in both upstream and downstream directions. This clause specifies the structure of the XGTC payload section, the format of the XGEM frame header and payload, the XGEM frame delineation principles, as well as the mapping of different service types into XGEM frames. + +## 9.1 XGEM framing + +### 9.1.1 XGTC payload structure + +The XGTC payload section is carried in the downstream XGTC frames and upstream XGTC bursts as shown in Figures 9-1 and 9-2. The size of the XGTC payload in a given downstream XGTC frame is equal to the XGTC frame size (which is fixed and equal to 135432 bytes) less the size of the given XGTC frame header. The size of each XGTC payload section in a given upstream burst is equal to the size of the respective allocation less the allocation overhead. The XGTC payload contains one or more XGEM frames (see Figure 9-1). + +![Diagram showing the structure of XGTC payload, which contains multiple XGEM frames. Each XGEM frame consists of an XGEM header and an XGEM payload. The diagram shows three XGEM frames concatenated within the XGTC payload section.](446100c084b94817a19c319fa776b412_img.jpg) + +The diagram illustrates the structure of an XGTC payload. At the top, a box labeled "XGTC payload (in DS XGTC frame or US XGTC burst)" has arrows pointing down to a sequence of three XGEM frames. Each XGEM frame is shown as a horizontal bar divided into two parts: "XGEM header" and "XGEM payload". Below these bars, the text "XGEM frame" is written under each of the three frames. The diagram is labeled "G.987.3(10)\_F9-1" in the bottom right corner. + +Diagram showing the structure of XGTC payload, which contains multiple XGEM frames. Each XGEM frame consists of an XGEM header and an XGEM payload. The diagram shows three XGEM frames concatenated within the XGTC payload section. + +**Figure 9-1 – Structure of XGTC payload** + +Each XGEM frame contains a fixed size XGEM header and a variable size XGEM payload field. + +### 9.1.2 XGEM frame header + +The size of the XGEM header is 8 bytes. The format of the XGEM header is shown in Figure 9-2. + +![Diagram of XGEM frame structure showing the header and payload. The header is expanded to show its fields: PLI (14 bits), Key index (2 bits), XGEM port-ID (16 bits), Options (18 bits), LF (1 bit), and HEC (13 bits).](e451401f8fa77b466f401d5fce15b26c_img.jpg) + +The diagram illustrates the XGEM frame structure. At the top, a box labeled 'XGEM frame' contains two sub-boxes: 'XGEM header' and 'XGEM payload'. Below this, the 'XGEM header' is expanded into a detailed view showing its constituent fields: 'PLI 14 bits', 'Key index 2 bits', 'XGEM port-ID 16 bits', 'Options 18 bits', 'LF 1 bit', and 'HEC 13 bits'. The text 'G.987.3(10)\_F9-2' is located at the bottom right of the diagram. + +Diagram of XGEM frame structure showing the header and payload. The header is expanded to show its fields: PLI (14 bits), Key index (2 bits), XGEM port-ID (16 bits), Options (18 bits), LF (1 bit), and HEC (13 bits). + +**Figure 9-2 – XGEM header format** + +The XGEM header has the following fields: + +**Payload length indication (PLI)** [14 bits]: The length $L$ , in bytes, of an SDU or an SDU fragment in the XGEM payload following the XGEM header. The 14-bit field allows to represent an integer from 0 to 16383, and, therefore, is sufficient to encode the length of an expanded Ethernet frame (up to 2000 bytes) as well as a jumbo Ethernet frame (up to 9000 bytes). The value of the PLI is accurate to a single byte and is not necessarily equal to the size of the XGEM payload which is aligned at the 4-byte word boundaries. + +**Key index** [2 bits]: The indicator of the data encryption key used to encrypt the XGEM payload. Depending on the XGEM Port-ID, the key index refers either to unicast or to broadcast key type. With up to two keys of each type being valid at any given time, the key index value of 01 refers to the first key, while the value of 10 refers to the second key. The value of 00 indicates that the payload is transmitted without encryption; the value of 11 is reserved for future use. If the key index of an XGEM frame contains a reserved value or points to an invalid key (see clause 15.5), the payload of the XGEM frame is discarded. + +**XGEM port-ID** [16 bits]: The identifier of XGEM Port to which the frame belongs. + +**Options** [18 bits]: The use of this field remains for further study. The field is set to 0x00000 by the transmitter and ignored by the receiver. + +**Last fragment (LF)** [1 bit]: The last fragment indicator. If the fragment encapsulated into the XGEM frame is the last fragment of an SDU or a complete SDU, the LF bit is set to 1; otherwise, LF bit is 0. + +**Hybrid error correction (HEC)** [13 bits]: The error detection and correction field for the XGEM header, which is a combination of a BCH(63, 12, 2) code operating on the 63 initial bits of the header and a single parity bit. The details of the HEC construction and verification are specified in Annex A. + +### 9.1.3 XGEM payload format + +The XGEM payload is a variable-length field controlled by the PLI field of the XGEM header. For a non-idle XGEM frame, the length $P$ of the XGEM payload, in bytes, is related to value $L$ , transmitted in the PLI field as: + +$$P = \begin{cases} 4 * \left\lceil \frac{L}{4} \right\rceil, & \text{if } L \geq 8 \\ 8, & \text{if } 0 < L < 8 \\ 0, & \text{if } L = 0 \end{cases} \quad (9-1)$$ + +The XGEM payload may contain one to seven bytes of padding in its least significant byte positions. The transmitter fills the padding bytes with 0x55. The padding bytes are discarded by the receiving XGEM engine. + +Figure 9-3 shows the XGEM payload format. + +![Diagram of XGEM payload format showing the relationship between an XGEM frame and its payload components.](ed48e24e36ea0501953177401c900f86_img.jpg) + +The diagram illustrates the XGEM payload format. At the top, a box labeled 'XGEM frame' contains two parts: 'XGEM header' and 'XGEM payload P bytes'. Below this, a larger box represents the payload content, divided into 'SDU or SDU fragment L bytes' and 'Pad 0..7 bytes'. Two arrows point from the 'XGEM payload P bytes' section of the top box to the 'SDU or SDU fragment L bytes' and 'Pad 0..7 bytes' sections of the bottom box, indicating that the payload consists of these two elements. The text 'G.987.3(14)-Amd.2(21)\_F9-3' is located at the bottom right of the diagram. + +Diagram of XGEM payload format showing the relationship between an XGEM frame and its payload components. + +**Figure 9-3 – XGEM payload format** + +### 9.1.4 Idle XGEM frame + +Whenever a transmitter has no SDUs or SDU fragments to send (this includes the case when the SDUs are ineligible for transmission as determined by a non-work-conserving scheduler), or the size of the SDU or SDU fragment exceeds the available XGTC payload section space but fragmenting it would violate the rules of clause 9.3, the transmitter shall generate Idle XGEM frames to fill the available XGTC payload section space. + +An idle XGEM frame is any XGEM frame with the value of XGEM port-ID equal to 0xFFFF. + +The PLI field of an Idle XGEM frame contains the actual size of the frame payload, which may be equal to any multiple of 4, including 0, up to the maximum supported SDU size. + +The idle XGEM frames are transmitted unencrypted with Key\_Index indicating no encryption and LF = 1. The receiver ignores the Key\_Index and LF fields of the header and the payload of the XGEM frame with XGEM port-ID of 0xFFFF. + +The XGEM payload content of an idle XGEM frame is formed by the transmitter at its own discretion with the necessary considerations given to the line pattern control and CID prevention. The idle XGEM frame payload is discarded by the receiver. + +If the available space at the end of XGTC payload section is less than the XGEM header size (i.e., is equal to 4 bytes), the transmitter shall generate a short idle XGEM frame, which is defined as four all-zero bytes. + +## 9.2 XGEM frame delineation + +The delineation process in XG-PON relies upon the presence of an XGEM header at the beginning of every downstream and upstream XGTC payload section. The receiver, which thus knows the location of the first XGEM header, can use the PLI field to determine the size of the XGEM payload and to find the location of the next XGEM header, repeating the procedure for all the subsequent XGEM frames. The receiver checks whether or not an XGEM frame has been delineated correctly by performing HEC verification on the header of the following XGEM frame. + +If HEC verification of the supposed XGEM header fails, the receiver should discard the current frame along with the remainder of the XGTC payload. Note that while the eventual recovery in case of a XGEM frame loss is possible in principle with the use of an XGEM frame delineation state machine (see [b-ITU-T G.984.3]), the event itself is very rare and the added complexity is considered excessive against the marginal performance improvement. + +## 9.3 SDU fragmentation + +SDU fragmentation is a process by which an SDU or an SDU fragment available for transmission in the downstream or upstream direction can be partitioned in two or more fragments and each SDU fragment be transmitted in a separate XGEM frame, as shown in Figure 9-4. + +![Diagram illustrating SDU fragmentation. At the top, a single SDU is shown. Below it, the SDU is split into two fragments: SDU fragment A and SDU fragment B. Each fragment is then encapsulated into an XGEM frame. XGEM frame A consists of an XGEM header and an XGEM payload, which contains SDU fragment A. XGEM frame B consists of an XGEM header and an XGEM payload, which contains SDU fragment B. The diagram is labeled G.987.3(10)_F9-4.](e64c7b989e5bdb2708cd7aefd18b06e1_img.jpg) + +Diagram illustrating SDU fragmentation. At the top, a single SDU is shown. Below it, the SDU is split into two fragments: SDU fragment A and SDU fragment B. Each fragment is then encapsulated into an XGEM frame. XGEM frame A consists of an XGEM header and an XGEM payload, which contains SDU fragment A. XGEM frame B consists of an XGEM header and an XGEM payload, which contains SDU fragment B. The diagram is labeled G.987.3(10)\_F9-4. + +**Figure 9-4 – SDU fragmentation** + +The downstream and upstream fragmentation is subject to the following respective rules. + +In the downstream direction, if the available XGTC payload in the current XGTC frame is at least 16 bytes, and the length of the SDU available for transmission, including the 8-byte XGEM header, exceeds that available payload, the SDU should be partitioned in two fragments, so that the first SDU fragment completely occupies the available payload of the current XGTC frame, while the second SDU fragment is transmitted in the XGTC payload of the next XGTC frame. If the size of second SDU fragment is less than 8 bytes, then it should be padded to 8 bytes to meet the 16 bytes minimum XGEM frame size requirement. Once SDU fragmentation has commenced, the second fragment of the SDU shall be transmitted prior to any other SDU; that is, downstream SDU pre-emption is not supported. + +In the upstream direction, if the available XGTC payload in the current allocation is at least 16 bytes, and the length of the SDU or SDU fragment scheduled for transmission, including the 8-byte XGEM header, exceeds that available payload, the SDU should be partitioned in two fragments, so that the first SDU fragment completely occupies the available XGTC payload in the current allocation, while the remainder of the SDU is transmitted in the XGTC payload of the next upstream allocation associated with the same Alloc-ID, being the subject to the same fragmentation rules. Once SDU fragmentation has commenced, all fragments of the SDU shall be transmitted prior to any other SDU associated with the same Alloc-ID; that is, upstream SDU pre-emption within a given Alloc-ID is not supported. + +The following additional rules apply to both the downstream and upstream directions: + +- If as a result of fragmentation, the second SDU fragment is less than 8 bytes, it should be padded to the minimum of 8 bytes to meet the minimum XGEM frame size of 16 bytes. +- If the length of the SDU or SDU fragment available for transmission, including the 8-byte XGEM header, is equal to or less than the available XGTC payload space, further fragmentation is prohibited: the entire available SDU or SDU fragment shall be transmitted in the current XGTC payload. +- If the size of the available XGTC payload is less than 16 bytes, it should be filled with an idle XGEM frame. + +## 9.4 Mapping of services into XGEM frames + +### 9.4.1 Ethernet over XGEM + +Ethernet frames are carried directly in the XGEM frame payload. The IEEE 802 preamble and start frame delimiter (SFD) bytes are discarded prior to XGEM encapsulation. Each Ethernet frame is mapped into a single XGEM frame, as shown in Figure 9-5, or into multiple XGEM frames. In the latter case, the fragmentation rules of clause 9.3 apply. An XGEM frame may not encapsulate more than one Ethernet frame. + +![Diagram showing the mapping of an Ethernet frame into an XGEM frame. The Ethernet frame structure includes Inter-packet gap (12), Preamble (7), SFD (1), DA (6), SA (6), Length/type (2), MAC client data (N), and FCS (4). The XGEM frame structure includes PLI, KI, XGEM port-ID, Options, LF, HEC, XGEM payload (N + 18), and Padding (0-3). A double-headed arrow indicates the mapping of the MAC client data into the XGEM payload.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +The diagram illustrates the mapping of an Ethernet frame into an XGEM frame. The Ethernet frame is shown on the left with its fields: Inter-packet gap (12), Preamble (7), SFD (1), DA (6), SA (6), Length/type (2), MAC client data (N), and FCS (4). The XGEM frame is shown on the right with its fields: PLI, KI, XGEM port-ID, Options, LF, HEC, XGEM payload (N + 18), and Padding (0-3). A double-headed arrow indicates the mapping of the MAC client data into the XGEM payload. The source is G.987.3(10)\_F9-5. + +Diagram showing the mapping of an Ethernet frame into an XGEM frame. The Ethernet frame structure includes Inter-packet gap (12), Preamble (7), SFD (1), DA (6), SA (6), Length/type (2), MAC client data (N), and FCS (4). The XGEM frame structure includes PLI, KI, XGEM port-ID, Options, LF, HEC, XGEM payload (N + 18), and Padding (0-3). A double-headed arrow indicates the mapping of the MAC client data into the XGEM payload. + +**Figure 9-5 – Ethernet mapping into an XGEM frame** + +### 9.4.2 MPLS over XGEM + +Multi-protocol label switching packets are carried directly in the XGEM frame payload. Each MPLS packet is mapped into a single XGEM frame, as shown in Figure 9-6, or into multiple XGEM frames. In the latter case, the fragmentation rules of clause 9.3 apply. An XGEM frame may not encapsulate more than one MPLS packet. + +Figure 9-6 shows MPLS packet mapping into an XGEM frame. + +![Diagram showing the mapping of an MPLS packet into an XGEM frame. The MPLS packet structure includes MPLS label stack (L) and MPLS payload (N). The XGEM frame structure is the same as in Figure 9-5. A double-headed arrow indicates the mapping of the MPLS packet into the XGEM payload.](4ff00a489baaa34a0c01070de1d613db_img.jpg) + +The diagram illustrates the mapping of an MPLS packet into an XGEM frame. The MPLS packet is shown on the left with its fields: MPLS label stack (L) and MPLS payload (N). The XGEM frame is shown on the right with its fields: PLI, KI, XGEM Port-ID, Options, LF, HEC, XGEM payload (N + L), and Padding (0-3). A double-headed arrow indicates the mapping of the MPLS packet into the XGEM payload. The source is G.987.3(10)\_F9-6. + +Diagram showing the mapping of an MPLS packet into an XGEM frame. The MPLS packet structure includes MPLS label stack (L) and MPLS payload (N). The XGEM frame structure is the same as in Figure 9-5. A double-headed arrow indicates the mapping of the MPLS packet into the XGEM payload. + +**Figure 9-6 – MPLS packet mapping into an XGEM frame** + +# 10 PHY adaptation sublayer + +This clause discusses matters of physical synchronization and delineation, forward error correction, and scrambling for the downstream and upstream transmission in XG-PON. + +## 10.1 Downstream PHY frame + +The OLT is continuously transmitting in the downstream direction. The OLT's transmission is partitioned into fixed size downstream PHY frames. The duration of a downstream PHY frame is 125 μs, which at the downstream rate of 9.95328 Gbit/s corresponds to the size of 155520 bytes (38880 words). A downstream PHY frame consists of a 24-byte physical synchronization block + +(PSBd) and a 155496-byte PHY frame payload represented by the downstream XGTC frame whose content is protected by FEC and scrambled. + +The start of a particular downstream PHY frame is defined in the context of the given network element and corresponds to transmission (by the OLT) or receipt (by the ONU) of the first bit of its PSBd. + +A diagram of the downstream PHY frame is shown in Figure 10-1. + +![Figure 10-1: Downstream PHY frame diagram. The diagram shows the transmission of a downstream PHY frame from an OLT to multiple ONUs (ONU_i and ONU_j). The frame consists of a 24-byte PSBd followed by a 155496-byte PHY frame payload. The total duration of the frame is 125 μs. The diagram illustrates the timing and sequence of the frame components as they are received by the ONUs.](329c96049bb432e9c2cbda4e224a0c9c_img.jpg) + +The diagram illustrates the transmission of a downstream PHY frame from an OLT to multiple ONUs. The frame structure is shown as a sequence of blocks: PSBd (24 bytes) and PHY frame payload (155496 bytes). The total duration of the frame is 125 μs. The OLT transmits the frame, and the ONUs (ONUi and ONUj) receive it. The diagram shows the timing of the frame components as they are received by the ONUs, with the PSBd being the first component received. + +Figure 10-1: Downstream PHY frame diagram. The diagram shows the transmission of a downstream PHY frame from an OLT to multiple ONUs (ONU\_i and ONU\_j). The frame consists of a 24-byte PSBd followed by a 155496-byte PHY frame payload. The total duration of the frame is 125 μs. The diagram illustrates the timing and sequence of the frame components as they are received by the ONUs. + +**Figure 10-1 – Downstream PHY frame** + +### 10.1.1 Downstream physical synchronization block (PSBd) + +The size of the downstream physical synchronization block (PSBd) is 24 bytes. It contains three separate 8-byte structures: PSync, superframe counter (SFC) structure, and PON-ID structure (see Figure 10-2). + +![Figure 10-2: Downstream physical synchronization block (PSBd) diagram. The diagram shows the internal structure of the PSBd, which is 24 bytes in total. It is divided into three 8-byte structures: PSync (8 bytes), SFC structure (8 bytes), and PON-ID structure (8 bytes). The PSync structure contains a 64-bit pattern. The SFC structure contains a 51-bit superframe counter (SFC) and a 13-bit HEC field. The PON-ID structure contains a 51-bit PON-ID and a 13-bit HEC field.](26e334e61dd059cff029338a2a604d8d_img.jpg) + +The diagram shows the internal structure of the PSBd. It is a 24-byte block divided into three 8-byte structures: PSync (8 bytes), SFC structure (8 bytes), and PON-ID structure (8 bytes). The PSync structure contains a 64-bit pattern. The SFC structure contains a 51-bit superframe counter (SFC) and a 13-bit HEC field. The PON-ID structure contains a 51-bit PON-ID and a 13-bit HEC field. + +Figure 10-2: Downstream physical synchronization block (PSBd) diagram. The diagram shows the internal structure of the PSBd, which is 24 bytes in total. It is divided into three 8-byte structures: PSync (8 bytes), SFC structure (8 bytes), and PON-ID structure (8 bytes). The PSync structure contains a 64-bit pattern. The SFC structure contains a 51-bit superframe counter (SFC) and a 13-bit HEC field. The PON-ID structure contains a 51-bit PON-ID and a 13-bit HEC field. + +**Figure 10-2 – Downstream physical synchronization block (PSBd)** + +#### 10.1.1.1 Physical synchronization sequence (PSync) + +The physical synchronization sequence contains a fixed 64-bit pattern. The ONU uses this sequence to achieve alignment at the downstream PHY frame boundary. The coding of the PSync field is 0xC5E5 1840 FD59 BB49. + +#### 10.1.1.2 Superframe counter structure + +The SFC structure is a 64-bit field that contains a 51-bit superframe counter (SFC) and a 13-bit HEC field (see Figure 10-2). The SFC value in each downstream PHY frame is incremented by one with respect to the previous PHY frame. Whenever the SFC reaches its maximum value (all ones), it is set to 0 on the following downstream PHY frame. + +The HEC field is a combination of a BCH(63, 12, 2) code operating on the 63 initial bits of the SFC structure and a single parity bit. The details of the HEC construction and verification are specified in Annex A. + +#### 10.1.1.3 PON-ID structure + +The PON-ID structure contains a 51-bit PON identifier and a 13-bit HEC field (see Figure 10-2). + +The PON-ID is set by the OLT at its discretion. Its default is 51 bits of zero. + +The HEC field is a combination of a BCH(63, 12, 2) code operating on the 63 initial bits of the PON-ID structure and a single parity bit. The details of the HEC construction and verification are specified in Annex A. + +#### 10.1.1.4 PSBd field scrambling + +After HEC calculation at the transmitter and prior to HEC verification at the receiver, the superframe counter and PON-ID structures are XOR'ed with the fixed pattern 0x0F0F0F0F0F0F0F0F. + +### 10.1.2 ONU downstream synchronization + +The OLT controls the subtending ONUs by timing their behaviour with respect to the start of the downstream PHY frame, as determined by the respective ONU. To operate on a PON, each ONU must be synchronized with the sequence of the downstream PHY frames. While the details of the synchronization mechanism are internal to the ONU and are not subject to standardization, the following description represents the reference synchronization state machine that is reasonably immune to both false lock (on an independent uniformly random bitstream) and false loss of synchronization (under high BER of up to $10^{-3}$ ). The vendor implementation of the ONU synchronization mechanism is expected to match the performance of the reference state machine. + +The reference implementation of the ONU downstream synchronization state machine is shown in Figure 10-3. + +The ONU begins in the Hunt state. While in the Hunt state, the ONU searches for the PSync pattern in all possible alignments (both bit and byte) within the downstream signal. Once an exact match with the PSync pattern specified in clause 10.1.1.1 is found, the ONU verifies if the 64 bits immediately following the PSync pattern form a valid (i.e., error-free or correctable) HEC-protected SFC structure (see Table A.4 for the HEC verification rules). If the 64-bit protected SFC structure is uncorrectable, the ONU remains in the Hunt state and continues searching for a PSync pattern. If the 64-bit protected SFC structure is valid, the ONU stores a local copy of the SFC value and transitions into the Pre-Sync state. + +![Downstream ONU synchronization state machine diagram showing four states: Hunt, Pre-sync, Sync, and Re-sync with transitions based on PSync and SFC verification.](f24f909d837b5476783e1bbea2dfc143_img.jpg) + +``` +stateDiagram-v2 + [*] --> Hunt + Hunt --> Hunt : PSync and/or SFC fails + Hunt --> Pre-sync : Exact PSync match and SFC usable + Pre-sync --> Hunt : PSync and/or SFC fails + Pre-sync --> Sync : Both PSync and SFC verified + Sync --> Hunt : M-1 consecutive PSync and/or SFC failures + Sync --> Sync : Both PSync and SFC verified + Sync --> Re-sync : PSync and/or SFC fails + Re-sync --> Hunt : PSync and/or SFC fails + Re-sync --> Sync : Both PSync and SFC verified +``` + +The diagram illustrates the downstream ONU synchronization state machine with four states: Hunt, Pre-sync, Sync, and Re-sync. Transitions are based on PSync and SFC verification results. The Hunt state is the initial state. Transitions from Hunt to Pre-sync occur on an exact PSync match and SFC usability. Transitions from Pre-sync to Sync occur when both PSync and SFC are verified. Transitions from Sync to Hunt occur after M-1 consecutive failures. Transitions from Sync to Re-sync occur on a failure. Transitions from Re-sync to Hunt occur on a failure, and from Re-sync to Sync occur on verification. Self-loops on Hunt, Sync, and Re-sync states indicate continued searching or re-synchronization upon failure. + +G.987.3(10)\_F10-3 + +Downstream ONU synchronization state machine diagram showing four states: Hunt, Pre-sync, Sync, and Re-sync with transitions based on PSync and SFC verification. + +Figure 10-3 – Downstream ONU synchronization state machine + +Once the ONU locates a boundary of a downstream PHY frame and leaves the Hunt state, it performs PSync and SFC verification on each subsequent PHY frame boundary (i.e., once every 155520 bytes) and executes a corresponding transition of the downstream synchronization state machine. Prior to PSync and SFC verification, the ONU increments the local SFC value by one. The first incoming 64-bit sequence at the boundary of a downstream PHY frame is considered a PSync field, whereas the subsequent 64-bit sequence is considered an SFC structure. The PSync verification is successful if at least 62 bits of the incoming 64-bit sequence match the fixed PSync pattern; otherwise, the PSync verification fails. The SFC verification is successful if the incoming 64-bit sequence forms a valid (error-free or correctable) HEC-protected field, and the incoming SFC value is equal to the locally stored (and just incremented) SFC value; otherwise, the SFC verification fails. + +Once in the Pre-Sync state, the ONU transitions to the Sync state if both PSync verification and SFC verification are successful, and returns to the Hunt state if either PSync verification or SFC verification fails. + +Once in the Sync state, the ONU remains in that state as long both PSync verification and SFC verification are successful, and transitions into the Re-Sync state, if either PSync verification or SFC verification fails. + +Once in the Re-Sync state, the ONU transitions back to Sync state if both PSync and SFC are successfully verified once. However, if for $M - 1$ consecutive PHY frames either PSync verification or SFC verification fails, the ONU declares loss of downstream synchronization, discards the local SFC copy, and transitions into the Hunt state. + +The recommended value of the parameter $M$ is 3. + +### 10.1.3 Downstream PHY frame payload + +The payload of a downstream PHY frame has the size of 155496 bytes. It is obtained from the corresponding downstream XGTC frame (see clause 8.1), which has the size of 135432 bytes, by applying FEC thus adding the total of 20064 parity bytes (clause 10.3.1), and scrambling the result (clause 10.4.1). + +## 10.2 Upstream PHY frames and upstream PHY bursts + +The duration of an upstream PHY frame is 125 $\mu\text{s}$ , which at the upstream rate of 2.48832 Gbit/s corresponds to the size of 38880 bytes (9720 words). + +As directed by the OLT, each ONU determines the point in time corresponding to the start of a particular upstream PHY frame by appropriately offsetting the starting point of the respective downstream PHY frame. The sequence of upstream PHY frame boundary points provides a common timing reference shared by the OLT and all the ONUs on the PON, but those points do not correspond to any specific event (unlike the downstream PHY frame boundary points, at which the transmission or receipt of a PSBd starts). + +In the upstream direction, each ONU transmits a series of relatively short PHY bursts and remains idle in-between the bursts. An upstream PHY burst consists of an upstream physical synchronization block (PSBu) and a PHY burst payload represented by the upstream XGTC burst whose content may be protected by FEC and is scrambled. The OLT uses the BWmap to control timing and duration of the upstream PHY bursts so that the upstream transmissions by different ONUs are non-overlapping. The upstream PHY bursts of each ONU are referenced to the start of the appropriate upstream PHY frame. An upstream PHY burst belongs to upstream PHY frame $N$ as long as this burst is specified in the BWmap transmitted with downstream PHY frame $N$ . If this is the case, the first byte of the XGTC burst header is transmitted within the boundaries of PHY frame $N$ . The PSBu portion of an upstream PHY burst may be transmitted within the boundaries of the previous PHY frame. An upstream PHY burst belonging to a particular upstream PHY frame may extend beyond the trailing boundary of that frame. + +The relationship between PHY framing boundaries and the upstream PHY bursts of different ONUs is illustrated in Figure 10-4. + +![Figure 10-4: Upstream PHY frame and upstream PHY bursts. The diagram shows three horizontal lines representing the OLT (top), ONU_i (middle), and ONU_j (bottom). The OLT line has three 'PHY burst' labels with double-headed arrows indicating their duration. The ONU_i line has two 'PSBu' blocks, each followed by a grey rectangle representing the payload. The ONU_j line has one 'PSBu' block followed by a grey rectangle. Dashed lines connect the start and end of the PSBu blocks on the ONUs to the corresponding PHY burst labels on the OLT. Below the ONU_j line, two 'Upstream PHY frame, 125 μs' labels with double-headed arrows indicate the frame duration. The text 'G.987.3(10)_F10-4' is in the bottom right corner.](bb4d2112ed07e2031c92fbff3494af9f_img.jpg) + +Figure 10-4: Upstream PHY frame and upstream PHY bursts. The diagram shows three horizontal lines representing the OLT (top), ONU\_i (middle), and ONU\_j (bottom). The OLT line has three 'PHY burst' labels with double-headed arrows indicating their duration. The ONU\_i line has two 'PSBu' blocks, each followed by a grey rectangle representing the payload. The ONU\_j line has one 'PSBu' block followed by a grey rectangle. Dashed lines connect the start and end of the PSBu blocks on the ONUs to the corresponding PHY burst labels on the OLT. Below the ONU\_j line, two 'Upstream PHY frame, 125 μs' labels with double-headed arrows indicate the frame duration. The text 'G.987.3(10)\_F10-4' is in the bottom right corner. + +**Figure 10-4 – Upstream PHY frame and upstream PHY bursts** + +### 10.2.1 Upstream physical synchronization block (PSBu) + +The PSBu section contains preamble and delimiter (see Figure 10-5) that allow the OLT's optical receiver to adjust to the level of the optical signal and to delineate burst. The length and pattern of preamble and delimiter constitute the profile of the burst. The set of allowed burst profiles is specified by the OLT in advance using the Profile PLOAM message. The specific profile to be used with the particular PHY burst is selected by the OLT in the BurstProfile field in the corresponding BWmap allocation. + +![Figure 10-5: Upstream physical synchronization block. The diagram shows a 'PSBu' block at the top, with two lines branching down to a 'Preamble' block and a 'Delimiter' block. The 'Preamble' and 'Delimiter' blocks are side-by-side. The text 'G.987.3(10)_F10-5' is in the bottom right corner.](9a14684f8ae1345c6efea6f5994c730c_img.jpg) + +Figure 10-5: Upstream physical synchronization block. The diagram shows a 'PSBu' block at the top, with two lines branching down to a 'Preamble' block and a 'Delimiter' block. The 'Preamble' and 'Delimiter' blocks are side-by-side. The text 'G.987.3(10)\_F10-5' is in the bottom right corner. + +**Figure 10-5 – Upstream physical synchronization block** + +See Appendix III for the discussion of preamble and delimiter patterns and recommended burst profiles. + +### 10.2.2 Upstream PHY burst payload + +The payload of an upstream PHY burst is obtained from the corresponding upstream XGTC burst (see clause 8.2) by optionally applying FEC, at the OLT discretion as controlled by the burst profile, (clause 10.3.2), and scrambling the result (clause 10.4.2). + +### 10.2.3 Guard time + +To prevent upstream transmissions from colliding and jamming each other, the OLT builds the BWmap allowing suitable guard time between upstream bursts from different ONUs. Guard time accommodates the Tx enable and Tx disable times, and includes the margin for the individual ONU transmission drift. The recommended minimum guard time is 64 bits. + +## 10.3 Forward error correction + +The PHY adaptation sublayer employs forward error correction (FEC) to introduce redundancy in the transmitted data. This allows the decoder to detect and correct certain transmission errors. In an XG-PON system, FEC encoding is based on Reed-Solomon (RS) codes. + +Reed-Solomon (RS) codes are non-binary codes, which operate on byte symbols and belong to the family of systematic linear cyclic block codes. An RS code takes a data block of constant size and adds extra parity bytes at the end, thus creating a codeword. Using those extra bytes, the FEC decoder processes the data stream, discovers errors, corrects errors, and recovers the original data. + +The most commonly used RS codes are RS(255, 239), where a 255-byte codeword consists of 239 data bytes followed by 16 parity bytes, and RS(255, 223), where a 255-byte codeword consists of 223 data bytes followed by 32 parity bytes. The RS(255, 239) code is specified in [ITU-T G.709]. + +This Recommendation employs RS codes in a truncated, or shortened, form, thus allowing to work with a more convenient codeword and data block size. The shortened codeword of 248 symbols is padded at the encoder with 7 leading zero symbols which are not transmitted but which are reinserted at the receiver prior to decoding. + +In the downstream direction, the FEC code is RS (248, 216), which is a truncated form of RS(255, 223) code. In the upstream direction, the FEC code is RS (248, 232), which is a truncated form of RS(255, 239) code. The RS(248, 216) and RS(248, 232) codes are formally described in Annex B. + +FEC support is mandatory for both OLT and ONU in the upstream as well as downstream directions. In the downstream direction, FEC is always on; in the upstream direction, the use of FEC is under dynamic control by the OLT. + +### 10.3.1 Downstream FEC + +The downstream FEC code is RS (248, 216). Each downstream PHY frame contains 627 FEC codewords. Each codeword is 248 bytes long. Within a codeword, 216 data bytes are followed by 32 parity bytes. + +The 24-byte PSBd section is not included in the FEC codeword. In a downstream PHY frame, the first codeword starts with the 25th byte of the PHY frame (the first byte of the XGTC header section), the second codeword starts from the 273rd byte of the PHY frame, the third codeword starts from the 521st byte of the PHY frame, and so on. The downstream FEC parity bytes insertion and payload reconstruction are shown in Figures 10-6 and 10-7, respectively. + +Note that the downstream FEC encoding processing step is applied before downstream scrambling. + +![Diagram illustrating the FEC parity bytes insertion in a downstream PHY frame. The diagram shows the mapping of data bytes from an XGTC frame to a PHY frame, with parity bytes being inserted. The XGTC frame (135432 bytes) contains an XGTC header and payload. The payload is divided into 627 codewords, each with 216 data bytes. These are mapped to the PHY frame (155520 bytes), which starts with a 24-byte PSBd section. Each codeword in the PHY frame consists of 216 data bytes followed by 32 parity bytes. Arrows show the mapping of data bytes from the XGTC payload to the PHY frame's data sections. Codeword #1 starts at the 25th byte of the PHY frame, and Codeword #627 ends at the 155520th byte.](0d0897dd7f03672d186db9d56ea0d6f5_img.jpg) + +The diagram illustrates the mapping of data bytes from an XGTC frame to a PHY frame. The XGTC frame (135432 bytes) contains an XGTC header and payload. The payload is divided into 627 codewords, each with 216 data bytes. These are mapped to the PHY frame (155520 bytes), which starts with a 24-byte PSBd section. Each codeword in the PHY frame consists of 216 data bytes followed by 32 parity bytes. Arrows show the mapping of data bytes from the XGTC payload to the PHY frame's data sections. Codeword #1 starts at the 25th byte of the PHY frame, and Codeword #627 ends at the 155520th byte. + +| Section | Size (bytes) | Start Byte | End Byte | +|----------------------|--------------|------------|----------| +| PSBd | 24 | 0 | 23 | +| Codeword #1 Data | 216 | 25 | 240 | +| Codeword #1 Parity | 32 | 241 | 272 | +| Codeword #2 Data | 216 | 273 | 488 | +| Codeword #2 Parity | 32 | 489 | 520 | +| ... | ... | ... | ... | +| Codeword #627 Data | 216 | 155205 | 155420 | +| Codeword #627 Parity | 32 | 155421 | 155452 | + +Diagram illustrating the FEC parity bytes insertion in a downstream PHY frame. The diagram shows the mapping of data bytes from an XGTC frame to a PHY frame, with parity bytes being inserted. The XGTC frame (135432 bytes) contains an XGTC header and payload. The payload is divided into 627 codewords, each with 216 data bytes. These are mapped to the PHY frame (155520 bytes), which starts with a 24-byte PSBd section. Each codeword in the PHY frame consists of 216 data bytes followed by 32 parity bytes. Arrows show the mapping of data bytes from the XGTC payload to the PHY frame's data sections. Codeword #1 starts at the 25th byte of the PHY frame, and Codeword #627 ends at the 155520th byte. + +Figure 10-6 – FEC parity bytes insertion in downstream PHY frame + +![Diagram of payload reconstruction at downstream FEC decoder. It shows a 'Downstream PHY frame, 155520 bytes' containing multiple codewords (Codeword #1, Codeword #2, ..., Codeword #627). Each codeword consists of 216 data bytes and 32 parity bytes, preceded by a 24-byte PSBd. Below this, the 'Corrected data of codeword #1, #2, ..., #627' are shown, each being 216 bytes. These are then mapped to a 'Downstream XGTC frame, 135432 bytes', which contains an XGTC header and an XGTC payload. Blue arrows show the mapping of data bytes from the codewords to the XGTC payload.](e8e818455bb0d1a6153299a388b94868_img.jpg) + +Diagram of payload reconstruction at downstream FEC decoder. It shows a 'Downstream PHY frame, 155520 bytes' containing multiple codewords (Codeword #1, Codeword #2, ..., Codeword #627). Each codeword consists of 216 data bytes and 32 parity bytes, preceded by a 24-byte PSBd. Below this, the 'Corrected data of codeword #1, #2, ..., #627' are shown, each being 216 bytes. These are then mapped to a 'Downstream XGTC frame, 135432 bytes', which contains an XGTC header and an XGTC payload. Blue arrows show the mapping of data bytes from the codewords to the XGTC payload. + +**Figure 10-7 – Payload reconstruction at downstream FEC decoder** + +### **10.3.2 Upstream FEC** + +The upstream FEC code is RS (248, 232). Each codeword is 248 bytes long. Within a codeword, 232 data bytes are followed by 16 parity bytes. The PSBu section is not included in the FEC codeword. The first codeword in a PHY burst begins with the XGTC header section. All allocations of a particular ONU have the same FEC status. Contiguous allocations are encoded as a single block of data, so that there is at most one shortened codeword at the end of the burst. The upstream FEC parity byte insertion and payload reconstruction at the decoder are shown in Figures 10-8 and 10-9, respectively. + +Note that the upstream FEC encoding processing step is applied before upstream scrambling. + +![Diagram of upstream transmission with FEC parity bytes insertion. It shows an 'Upstream XGTC burst' containing an XGTC header, upstream allocations (232 bytes each), and an XGTC trailer. Below this, the 'Data bytes of codeword #1, ..., #K, last codeword' are shown. These are then mapped to an 'Upstream PHY burst' which includes a PSBu, data bytes, and parity bytes (16 bytes) for each codeword. The last codeword is shortened to L data bytes. Blue arrows show the mapping of data bytes from the XGTC burst to the PHY burst codewords.](67d03c9e89620d73e3786c869e559752_img.jpg) + +Diagram of upstream transmission with FEC parity bytes insertion. It shows an 'Upstream XGTC burst' containing an XGTC header, upstream allocations (232 bytes each), and an XGTC trailer. Below this, the 'Data bytes of codeword #1, ..., #K, last codeword' are shown. These are then mapped to an 'Upstream PHY burst' which includes a PSBu, data bytes, and parity bytes (16 bytes) for each codeword. The last codeword is shortened to L data bytes. Blue arrows show the mapping of data bytes from the XGTC burst to the PHY burst codewords. + +**Figure 10-8 – Upstream transmission with FEC parity bytes insertion** + +![Diagram illustrating payload reconstruction at the upstream FEC decoder. The top section shows an 'Upstream PHY burst' containing a 'PSBu' block followed by multiple codewords: 'Codeword #1' (232 bytes data + 16 bytes parity), 'Codeword #K' (232 bytes data + 16 bytes parity), and a 'Last (short) codeword' (L ≤ 232 bytes data + 16 bytes parity). The bottom section shows the 'Upstream XGTC burst' after decoding, where the parity bytes are removed. It contains 'Corrected data of codeword #1' (232 bytes), 'Corrected data of codeword #K' (232 bytes), and 'Corrected data of last codeword' (L bytes). These are surrounded by 'XGTC header', 'Upstream allocation' fields, and an 'XGTC trailer'. Arrows indicate the mapping of data bytes from the PHY burst codewords to the XGTC burst corrected data blocks.](0a42e05c07941450f34e4f7117725834_img.jpg) + +Diagram illustrating payload reconstruction at the upstream FEC decoder. The top section shows an 'Upstream PHY burst' containing a 'PSBu' block followed by multiple codewords: 'Codeword #1' (232 bytes data + 16 bytes parity), 'Codeword #K' (232 bytes data + 16 bytes parity), and a 'Last (short) codeword' (L ≤ 232 bytes data + 16 bytes parity). The bottom section shows the 'Upstream XGTC burst' after decoding, where the parity bytes are removed. It contains 'Corrected data of codeword #1' (232 bytes), 'Corrected data of codeword #K' (232 bytes), and 'Corrected data of last codeword' (L bytes). These are surrounded by 'XGTC header', 'Upstream allocation' fields, and an 'XGTC trailer'. Arrows indicate the mapping of data bytes from the PHY burst codewords to the XGTC burst corrected data blocks. + +**Figure 10-9 – Payload reconstruction at upstream FEC decoder** + +#### 10.3.2.1 Shortened last codeword + +Whenever there are fewer than 232 data bytes in the last codeword of a PHY burst, the FEC encoder generates a shortened last codeword as follows: + +- Extra zero padding bytes are added at the beginning of the last codeword to fill it to 232 bytes. +- The parity bytes are calculated. +- The padding bytes are removed and the shortened codeword is transmitted. + +The FEC decoder at the OLT conducts the following steps to decode the shortened last codeword: + +- The extra zero padding bytes are inserted at the beginning of the shortened last codeword. +- Following the decoding process, the padding bytes are removed. + +#### 10.3.2.2 BWmap considerations + +When building the BWmap, the OLT should take the usage of FEC into account, and strive to provide allocations that will result in an integral number of FEC blocks whenever FEC is utilized. + +Once the GrantSizes for the allocations within a XGTC burst are computed, the OLT may calculate the size of the corresponding PHY burst in the following steps: + +- 1) The size of the XGTC burst is equal to total of the sum of the GrantSizes, the fixed portion of the XGTC header, the XGTC trailer, and the 48-byte PLOAM field if the PLOAMu flag is set. +- 2) If the requested burst profile includes FEC, the FEC overhead is equal to a 16-byte parity block for each whole and possibly for one partial 232-byte data block within the XGTC burst. +- 3) Then the total size of the PHY burst is equal to the size of the XGTC burst, the FEC overhead (if applicable), and the size of the PSBu block. The size of the PSBu block is determined by the profile chosen by the OLT. + +Once the StartTime for the given PHY burst is assigned, the StartTime of the next PHY burst within the BWmap should be spaced by, at least, the sum of the following: the size of the given XGTC burst with FEC overhead, if applicable, the minimum guard time, and the size of the PSBu block of the next PHY burst. + +#### 10.3.2.3 Upstream FEC on/off control + +The OLT dynamically activates or deactivates the FEC functionality for a given ONU in the upstream direction by selecting the appropriate burst profile. When FEC is active, the FEC decoder provides the estimate of the BER on the upstream link. FEC can be turned off, if the observed BER is very low + +and if the operator is comfortable with the tradeoff between the throughput gain and the effective BER increase. When FEC is deactivated, the BER estimate is obtained using the BIP-32 value in the XGTC trailer. The operator can activate the FEC again if the observed BER is too high. + +## 10.4 Scrambling + +### 10.4.1 Scrambling of the downstream PHY frame + +The downstream PHY frame is scrambled using a frame-synchronous scrambling polynomial. The polynomial used is $x^{58} + x^{39} + 1$ . This pattern is added modulo two to the downstream data. The shift register used to calculate this polynomial is reset by a preload pattern at the first bit following the PSBd block, and is allowed to run until the last bit of the downstream PHY frame. + +The preload pattern, which is 58 bits long, changes for every downstream PHY frame. The most significant 51 bits of the preload (P1...P51) are represented by the 51-bit superframe counter transmitted in the PSBd block, so that P51, which is the MSB of the preload, equals the MSB of the superframe counter. The seven least significant bits of the preload are set to 1. + +A diagram of the downstream and upstream PHY frame scrambling is shown in Figure 10-10. An example of a scrambler sequence is shown in Annex A. + +![Figure 10-10: Downstream and upstream PHY frame scrambler diagram. The diagram shows a shift register with 58 stages, represented by D flip-flops labeled X^0, X^1, ..., X^39, ..., X^57, X^58. The feedback path from X^58 is XORed with the input 'Data in' to produce 'Scrambled data out'. The feedback path also branches off to an XOR gate that feeds back into the input of the X^0 flip-flop. The shift register is initialized with a preload pattern: 1 1 1 1 1 1 1 P1 ... P32 P33 ... P50 P51. Control signals 'clk' and 'set' are shown connected to the flip-flops. The diagram is labeled G.987.3(10)_F10-10.](683f755e8456c884716de4fce48c7e63_img.jpg) + +Figure 10-10: Downstream and upstream PHY frame scrambler diagram. The diagram shows a shift register with 58 stages, represented by D flip-flops labeled X^0, X^1, ..., X^39, ..., X^57, X^58. The feedback path from X^58 is XORed with the input 'Data in' to produce 'Scrambled data out'. The feedback path also branches off to an XOR gate that feeds back into the input of the X^0 flip-flop. The shift register is initialized with a preload pattern: 1 1 1 1 1 1 1 P1 ... P32 P33 ... P50 P51. Control signals 'clk' and 'set' are shown connected to the flip-flops. The diagram is labeled G.987.3(10)\_F10-10. + +Figure 10-10 – Downstream and upstream PHY frame scrambler + +### 10.4.2 Scrambling of the upstream PHY burst + +The upstream PHY burst is scrambled using a burst-synchronous scrambling polynomial. The polynomial used is $x^{58} + x^{39} + 1$ . This pattern is added modulo two to the upstream data. The shift register used to calculate this polynomial is reset by a preload pattern at the first bit following the PSBu block, and is allowed to run until the last bit of the PHY burst. + +The preload pattern, which is 58 bits long, changes for every upstream PHY frame. If an ONU transits multiple PHY bursts within the same PHY frame, the preload pattern for these bursts remains the same. The most significant 51 bits of the preload (P1...P51) are represented by the 51-bit superframe counter received in the PSBd block of the corresponding downstream PHY frame. The seven least significant bits of the preload are set to 1. + +A diagram of the upstream PHY burst scrambling is shown in Figure 10-10. An example of a scrambler sequence can be found in Annex A. + +# 11 PLOAM messaging channel + +## 11.1 Overview + +The physical layer OAM (PLOAM) messaging channel in an XG-PON system is an operations and management facility between OLT and ONUs that is based on a fixed set of messages transported within a designated field of the XGTC frame header (downstream) and the XGTC burst header + +(upstream). The OLT and ONU PLOAM processing engines appear as clients of the respective XGTC framing sublayers. The PLOAM channel provides more flexible functionality than the embedded management channel and is generally faster than the OMCI channel. + +### 11.1.1 PLOAM channel functionality + +The PLOAM channel supports XG-PON TC layer management functions. It is based upon exchange of 48-byte messages that are transported in the PLOAM partition of the downstream XGTC frame header and in the upstream XGTC burst header. + +The PLOAM channel supports the following functions: + +- Burst profile communication; +- ONU activation; +- ONU registration; +- Encryption key update exchange; +- Protection switching signalling; +- Power management. + +### 11.1.2 PLOAM channel rate limitations + +Downstream PLOAM messages fall into two categories, those that are broadcast to all ONUs, and those that are unicast to a specific ONU. Within a given 125 µs frame, the OLT may transmit at most one broadcast PLOAM message and at most one unicast PLOAM message to each ONU. + +The ONU should be able to store eight unicast and broadcast downstream PLOAM messages before they are processed. The PLOAM processing model is single threaded. The normative processing time of a PLOAM message is 750 µs. That is, once a downstream PLOAM message is received in an empty queue in downstream PHY frame $N$ , the ONU should be able to remove the message from the queue, perform all associated processing, and generate a response to be sent upstream not later than in upstream PHY frame $N + 6$ . Furthermore, if at the start of the upstream frame in which a PLOAM response is sent upstream, the PLOAM queue remains not empty, the message at the head of the queue should be processed and the response, if required for the given message type, be prepared for upstream transmission not later than in the 6th subsequent upstream PHY frame. + +Note that under these requirements, the OLT can determine the maximum number of unacknowledged broadcast and unicast PLOAM messages directed to a given ONU as well as the expected response time for any downstream PLOAM message. + +The ONUs transmit upstream PLOAM messages under the control of the OLT, which explicitly sets the PLOAMu flag in the respective allocation structures. The OLT should grant regular PLOAM transmission opportunities to each ONU. The OLT may modulate the rate at which it grants upstream PLOAMu transmission opportunities to the individual ONUs based on the ONU type, provisioned operating and service parameters, number and types of PLOAM messages being transmitted downstream, and the ONU's own feedback in the form of the PLOAM queue status indication. + +### 11.1.3 PLOAM channel robustness + +When as a result of unicast PLOAM message processing the ONU enters or remains in the Operation state (see clause 12), it acknowledges the processing outcome by generating an upstream PLOAM message. Such a response PLOAM can be either of a specific type required by the particular PLOAM protocol, or of the general Acknowledgement type. An Acknowledgement PLOAM message is generated also in case of a downstream PLOAM format or processing error. Both a specific type response and the Acknowledgement type response carry the sequence number of the downstream message being acknowledged. In addition, the Acknowledgement type response carries a completion code that indicates the outcome of PLOAM message processing. + +Moreover, a PLOAM message of Acknowledgement type is used in response to a PLOAM allocation when no upstream PLOAM is available for transmission. In this case, the completion code allows to distinguish between the idle condition (no PLOAM message in the transmit queue or being processed) and the busy condition (the PLOAM upstream transmit queue is empty, but a downstream PLOAM message is being processed). + +Broadcast downstream PLOAM messages that require no response (the Key\_Control message requires a response even when it is broadcast) and downstream PLOAM messages that fail the integrity check are not acknowledged. + +If the OLT expects the ONU to acknowledge or respond to a message, and instead receives merely a keep-alive acknowledgement to a PLOAM request, it can infer that the ONU has failed to process the message. If ONU *i* repeatedly fails to acknowledge a downstream PLOAM message, the OLT detects the loss of PLOAM channel *i* (LOPC*i*) defect. + +### 11.1.4 Extensibility + +The implementation of the PLOAM channel should be flexible to accommodate future enhancements in a backward-compatible way. + +## 11.2 PLOAM message format + +The PLOAM message structure is shown in Table 11-1, with each field being further defined in the following clauses. + +**Table 11-1 – Generic PLOAM message structure** + +| Octet | Field | Description | +|-------|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Ten bits, aligned at the LSB end of the 2-byte field. The six most significant bits are reserved, and should be set to 0 by the transmitter and ignored by the receiver. | +| 3 | Message type ID | This byte indicates the message type. The enumerated code point for each message type is defined below. | +| 4 | SeqNo | Sequence number. | +| 5-40 | Message_Content | The message content is defined in the clause that describes each message type ID. | +| 41-48 | MIC | Message integrity check. | + +### 11.2.1 ONU-ID + +The ONU-ID field includes six reserved bits, plus an actual 10-bit ONU identifier that specifies the message recipient in the downstream direction or the message sender in the upstream direction. During ONU activation, the ONU is assigned an ONU-ID in the range from 0 to 1022. The reserved ONU-ID value 1023 (0x3FF) indicates a broadcast message in the downstream direction or an ONU that has not been assigned an ONU-ID in the upstream direction. + +### 11.2.2 Message type ID + +Message type ID is an 8-bit field that indicates the type of the message and defines the semantics of the message payload. Message type ID code points are defined in clause 11.3 below. Message type ID code points that are not explicitly defined in this Recommendation are reserved. Reserved Message type ID code points should not be allocated by any vendor for any purpose and should not be transmitted in a PLOAM message. Upon receipt of an upstream PLOAM message with an unsupported message type ID, an OLT should ignore the message, including the sequence number field. Upon receipt of a downstream PLOAM message with a reserved or unsupported message type + +ID, an ONU should ignore the message, if it was sent with the broadcast ONU-ID, or negatively acknowledge the message as an unknown message type, if it was sent to that specific ONU-ID. + +### 11.2.3 SeqNo + +SeqNo is an 8-bit field containing a sequence number counter that is used to ensure robustness of the PLOAM messaging channel. + +In the downstream direction, the SeqNo field is populated with the value of a corresponding OLT sequence number counter. The OLT maintains a separate sequence number counter for each ONU unicast and for the broadcast PLOAM message flow. The counter for the broadcast PLOAM message flow is initialized to 1 upon OLT reboot. For each ONU, the OLT initializes the sequence number counter to 1 upon ONU-ID assignment. Upon transmission of a broadcast or unicast PLOAM message, the appropriate sequence number counter is incremented. Each sequence number counter rolls over from 255 to 1; the value 0 is not used downstream. + +In the upstream direction, whenever an upstream PLOAM message is a response to a downstream PLOAM message, the content of the SeqNo field is equal to the content of the SeqNo field of the downstream message. The same SeqNo may appear on more than one upstream PLOAM message; for example, for the conveyance of a multi-fragment encryption key. If a PLOAM message is originated autonomously by the ONU, for example, Serial\_Number\_ONU sent in response to a serial number grant, the value SeqNo = 0 is used. The value SeqNo = 0 is also used in responses to PLOAM grants at times when the ONU has no upstream PLOAM messages enqueued. + +### 11.2.4 Message content + +Octets 5 to 40 of the PLOAM message are used for the payload of PLOAM messages. The message payload content is specific to a particular message type ID and is defined in clause 11.3. Unused octets of the message payload content are padded with the value 0x00 by the transmitting PLOAM processor and are ignored by the receiving PLOAM processor. + +### 11.2.5 Message integrity check + +The message integrity check (MIC) is an 8-byte field that is used to verify the sender's identity and to prevent a forged PLOAM message attack. A PLOAM message is discarded by the receiver if its message integrity check fails. For the purpose of MIC verification, there is no distinction between the significant octets and padding octets of the message payload content. + +MIC generation is specified in clause 15.6. Key generation and management for PLOAM MIC is specified in clause 15.8. + +Using the PLOAM message content and the shared PLOAM integrity key, the sender computes the MIC and transmits it with the PLOAM message. Using the same message content and shared key, the receiver computes its version of the MIC and compares it with the MIC value carried in the received PLOAM message. If the two MIC values are equal, the PLOAM message is valid. Otherwise, the message is declared invalid and should be discarded. + +## 11.3 PLOAM message definitions + +### 11.3.1 Downstream message summary + +Table 11-2 summarizes the downstream messages. + +**Table 11-2 – Downstream PLOAM messages** + +| Message type ID | Message name | Function | Trigger | Effect of receipt | +|-----------------|-------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0x01 | Profile | Broadcast or unicast message to provide upstream burst header information. | Periodically at the OLT's discretion. | The ONU stores the profile for use in subsequent upstream transmissions.
If in state O5 and responding to directed Profile message, send Acknowledgement. | +| 0x03 | Assign_ONU-ID | To link a free ONU-ID value with the ONU's serial number. | When the OLT recognizes the unique serial number of an ONU during the discovery process. | The ONU with this serial number sets its ONU-ID and also its default Alloc-ID and OMCC XGEM port-ID.
No Acknowledgement. | +| 0x04 | Ranging_Time | To indicate the round-trip equalization delay EqD.
As a broadcast message, may be used to offset the EqD of all ONUs (e.g., after a protection switching event). | When the OLT decides that the delay must be updated. See the ONU activation process description in clause 12. | The ONU fills or updates the equalization delay register with this value.
If in or transitioning to state O5 and responding to directed Ranging_Time message, send Acknowledgement. | +| 0x05 | Deactivate_ONU-ID | To instruct a specific ONU to stop sending upstream traffic and reset itself. It can also be a broadcast message. | At the OLT's discretion. | The ONU with this ONU-ID switches off its laser. The ONU-ID, default and explicit Alloc-IDs, default XGEM Port-ID, burst profiles, and equalization delay are discarded. The ONU moves to the Initial state.
No Acknowledgement. | + +**Table 11-2 – Downstream PLOAM messages** + +| Message type ID | Message name | Function | Trigger | Effect of receipt | +|-----------------|-----------------------|---------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0x06 | Disable_Serial_Number | Broadcast message to disable/enable ONU with this serial number. | At the OLT's discretion. | Disable option: Moves the specified ONU, or all ONUs, to the Emergency Stop state. The disabled ONU is prohibited from transmitting.
Enable option: Moves the specified ONU or all ONUs in the Emergency Stop state to the Initial state. The enabled ONU discards the TC layer configuration and restarts the activation process, as specified in clause 12.
No Acknowledgement. | +| 0x09 | Request_Registration | To request an ONU's registration ID. | At the OLT's discretion; ONU has been previously activated. | Send the Registration message. | +| 0x0A | Assign_Alloc-ID | To assign a specified Alloc-ID to a particular ONU. | As part of service provisioning. The default Alloc-ID for OMCC need not be explicitly assigned. | The ONU acknowledges the message and responds henceforth to bandwidth grants to this Alloc-ID. | +| 0x0D | Key_Control | The OLT instructs the ONU to generate a new data encryption key or to confirm an existing data encryption key | At the OLT's discretion. | Send one Key_Report message for each 32-byte fragment of response content. | +| 0x12 | Sleep_Allow | To enable or disable ONU power saving in real time. | At the OLT's discretion. | If the ONU power management has been enabled via OMCI, the ONU response is controlled by the state machine of clause 16. Otherwise, the ONU ignores the message. | + +### 11.3.2 Upstream message summary + +Table 11-3 summarizes the upstream messages. + +**Table 11-3 – Upstream messages** + +| Message ID | Message name | Function | Trigger | Effect of receipt | +|-------------------|---------------------|--------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0x01 | Serial_Number_ONU | To report the serial number of the ONU. | When the ONU is in the Serial_Number state, it sends this message in response to a serial number grant. | The OLT extracts the serial number and can assign a free ONU-ID to this ONU. Included in the message is the current random delay, which enables the first round-trip delay (RTD) measurement during serial number acquisition. | +| 0x02 | Registration | To report the registration ID of an ONU. | When the ONU is in the Ranging state or is responding to a ranging grant, or when the ONU is in the Operation state and is responding to the Request_Registration message. | The OLT may use the ONU's registration ID as described further in clause 15.2.1. | +| 0x05 | Key_Report | To send a fragment of a new data encryption key or a hash of an existing data encryption key | In response to Key_Control message from the OLT | See clause 15.5.1 for the details of the protocol. | +| 0x09 | Acknowledgement | To indicate reception of specified downstream messages. Also used for no-op, error and busy responses. | Upon receipt of a downstream message that requires acknowledgement. Also to report busy, error or no upstream message. | This message provides for reliable transport of downstream messages as well as error responses and a no-op. | +| 0x10 | Sleep_Request | To signal the ONU's intention to start or terminate power saving | Under state machine control. | Defined in clause 16. | + +### 11.3.3 Downstream message formats + +#### 11.3.3.1 Profile message + +Burst profile information is transmitted periodically, at intervals of hundreds of milliseconds or longer. The version of a specific burst profile definition may change over time, so an ONU is expected to update itself with the latest version each time the message appears. To ensure that all ONUs are up to date, the OLT is expected not to make use of the changed information until each ONU has had a chance to receive the updated burst profile at least twice while it is in one of its awake states (see clause 16). + +The burst profile information accumulated by the ONU does not persist across ONU activations. A newly activated ONU may respond to a broadcast serial number grant only after it has acquired the burst profile information associated with the grant. More generally, an ONU in any state can respond to an allocation structure only if it has previously acquired the corresponding burst profile information. + +The OLT is responsible for understanding the consequences of sending both broadcast and unicast Profile messages. Specifically, for each individual ONU, the latest received Burst\_Profile message, either unicast or broadcast, which pertains to a specific burst profile index overwrites the previously stored burst profile for that index. + +| Octet | Content | Description | +|-------|-----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed message to one ONU or broadcast message to all ONUs. As a broadcast to all ONUs, ONU-ID = 0x03FF. | +| 3 | 0x01 | Message type ID "Profile". | +| 4 | SeqNo | Unicast or broadcast PLOAM sequence number, as appropriate. | +| 5 | VVVV 00PP | VVVV – Four-bit profile version. If the content of the profile changes, the OLT should ensure that the version also changes, so that the ONU can detect updates solely on the basis of the version field.
PP – Two-bit profile index. | +| 6 | 0000 000F | FEC indication. F = 1: FEC on, F = 0: FEC off. | +| 7 | 0000 DDDD | DDDD – Delimiter length in octets; four-bit integer, range 0..8. | +| 8-15 | Delimiter | Aligned with the most significant end of the field; padded with 0x00; padding treated as "don't care" by the receiver. | +| 16 | 0000 LLLL | LLLL – Preamble length in octets; four-bit integer; range 1-8. | +| 17 | 000R RRRR | RRRR – Five-bit preamble repeat count, range 0-31. The value 0 specifies that the preamble is not transmitted at all. | +| 18-25 | Preamble | Preamble pattern, aligned with the most significant end of the field; padded with 0x00; padding treated as "don't care" by the receiver. | +| 26-33 | PON-TAG | An 8-byte static identity of the OLT PON port that is chosen by the operator and is used to bind the master session key (MSK) to the context of the security association (see clause 15.3.3). It is recommended that PON-TAG be unique within at least the operator's domain and fixed for the lifetime of the system. For example, it may be obtained as a concatenation of 4-byte OLT Vendor-ID and a 4-byte VSSN of the PON port. | +| 34-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +#### 11.3.3.2 Assign\_ONU-ID message + +| Octet | Content | Description | +|-------|-----------|-----------------------------------------------------------------------------------------------------| +| 1-2 | 0x03FF | Broadcast ONU-ID. | +| 3 | 0x03 | Message type ID "Assign_ONU-ID". | +| 4 | SeqNo | Broadcast PLOAM sequence number. | +| 5-6 | ONU-ID | LSB-justified 10-bit assigned ONU-ID value padded with 6 MSB zeros; range 0-1022 (0x0000 – 0x03FE). | +| 7-10 | Vendor-ID | ONU Vendor-ID code, a four-character combination discovered at SN acquisition. | +| 11-14 | VSSN | Vendor-specific serial number, a four-byte unsigned integer discovered at SN acquisition. | +| 15-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +#### 11.3.3.3 Ranging\_Time message + +In its typical application, the Ranging\_Time message is used to establish the equalization delay for a given ONU (directed message), as described in clause 12. As a broadcast message, the Ranging\_Time message may be used to specify a delay offset adjustment, either positive or negative, to all ONUs, after a protection switching event. The OLT is responsible to consider the interaction between broadcast Ranging\_Time and possible power management states of its ONUs. + +| Octet | Content | Description | +|-------|-------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed message to one ONU or broadcast message to all ONUs. As a broadcast to all ONUs, ONU-ID = 0x03FF. | +| 3 | 0x04 | Message type ID "Ranging_Time". | +| 4 | SeqNo | Unicast or broadcast PLOAM sequence number. | +| 5 | 0000 00SP | Bit mask that indicates how the EqualizationDelay field is to be interpreted.
Bit P = 1-The delay in bytes 6-9 is absolute; ignore S.
Bit P = 0-The delay in bytes 6-9 is relative; S determines sign.
Bit S = 0-Positive: increase the current EqD by the specified value.
Bit S = 1-Negative: decrease the current EqD by the specified value. | +| 6-9 | EqualizationDelay | Equalization delay value, bit times with respect to the nominal upstream line rate of 2.48832 Gbit/s. | +| 10-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +#### 11.3.3.4 Deactivate\_ONU-ID message + +Either the single ONU addressed by this command, or all ONUs on the PON, unconditionally stops transmitting upstream. They discard their ONU-IDs and all Alloc-IDs and XGEM port-IDs and move to the Serial\_Number state. + +| Octet | Content | Description | +|-------|-------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed message to one ONU or broadcast message to all ONUs. As a broadcast to all ONUs, ONU-ID = 0x03FF. | +| 3 | 0x05 | Message type ID "Deactivate_ONU-ID". | +| 4 | SeqNo | Unicast or broadcast PLOAM sequence number, as appropriate. | +| 5-6 | Reason Code | OLT's reason to send the Deactivate_ONU-ID message. Set to 0x0000, if not supported or not specified. The suggested non-default codes available for use are listed in [b-G Suppl. 84]. An aware ONU's action is limited to logging the value. | +| 7-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check computed using the default PLOAM integrity key (see clause 15.8). | + +#### 11.3.3.5 Disable\_Serial\_Number message + +| Octet | Content | Description | +|-------|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | 0x03FF | Broadcast ONU-ID. | +| 3 | 0x06 | Message type ID "Disable_Serial_Number". | +| 4 | SeqNo | Broadcast PLOAM sequence number. | +| 5 | Disable/enable | 0xFF-The ONU with this serial number is denied upstream access.
0x00-The ONU with this serial number is allowed upstream access.
0x0F-All ONUs are denied upstream access. The content of bytes 6-13 is ignored.
0xF0-All ONUs are allowed upstream access. | +| 6-9 | Vendor-ID | ONU Vendor-ID code, a four-character combination discovered at SN acquisition. | +| 10-13 | VSSN | Vendor-specific serial number, a four-byte unsigned integer discovered at SN acquisition. | +| 14-15 | Reason Code | OLT's reason to send the Disable_SN message. Set to 0x0000, if not supported or not specified. The suggested non-default codes available for use are listed in [b-G Suppl.84]. An aware ONU's action is limited to logging the value. | +| 16-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +#### 11.3.3.6 Request\_Registration message + +| Octet | Content | Description | +|-------|---------|-------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed message to one ONU. | +| 3 | 0x09 | Message type ID "Request_Registration". | +| 4 | SeqNo | Unicast PLOAM sequence number. | +| 5-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check computed using the default PLOAM integrity key (see clause 15.8). | + +#### 11.3.3.7 Assign\_Alloc-ID message + +| Octet | Content | Description | +|-------|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed message to one ONU. | +| 3 | 0x0A | Message type ID "Assign_Alloc-ID". | +| 4 | SeqNo | Unicast PLOAM sequence number. | +| 5-6 | Alloc-ID-value | 14 bits, aligned to the least significant end. The most significant bits are set to 0 by the transmitter and treated as "don't care" by the receiver. | +| 7 | Alloc-ID-type | 1-XGEM-encapsulated payload.
255-Deallocate this Alloc-ID.
Other values reserved. | +| 8-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +#### 11.3.3.8 Key\_Control message + +| Octet | Content | Description | +|-------|------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed or broadcast message to instruct one or all ONUs to generate new keying material or confirm their existing keys. As a broadcast message, ONU-ID = 0x03FF. | +| 3 | 0x0D | Message type ID "Key_Control". | +| 4 | SeqNo | Unicast or broadcast PLOAM sequence number, as appropriate. | +| 5 | Reserved | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 6 | 0000 000C | Control:
0-Generate: The ONU shall generate a new data encryption key and send it upstream.
1-Confirm: The ONU shall send upstream a hash of the existing data encryption key (Key_Name). | +| 7 | 0000 00bb | bb: Key index
01-First key of a key pair.
10-Second key of a key pair. | +| 8 | Key_Length | Required key length, bytes. The value 0 specifies a key of 256 bytes (Note). | +| 9-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +NOTE – This parameter supports the long-term extensibility of the data encryption key exchange protocol. The currently specified cryptographic method for the data encryption, the AES-128 cipher (see clause 15.4) uses the fixed size key of 16 bytes. + +#### 11.3.3.9 Sleep\_Allow message + +The OLT sends Sleep\_Allow to enable or disable power saving in real time. If ONU power management has not been enabled via OMCI, the ONU silently discards this message. Clause 16 defines the use and function of this message in detail. + +| Octet | Content | Description | +|-------|-----------|--------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Directed or broadcast ONU-ID. As a broadcast message, ONU-ID = 0x03FF. | +| 3 | 0x12 | Message type ID "Sleep_Allow". | +| 4 | SeqNo | Unicast or broadcast PLOAM sequence number, as appropriate. | +| 5 | 0000 000A | This byte is a bit field with the following significance:
A = 0-Sleep allowed OFF.
A = 1-Sleep allowed ON.
Other values reserved. | +| 6-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +### 11.3.4 Upstream message formats + +#### 11.3.4.1 Serial\_Number\_ONU message + +| Octet | Content | Description | +|-------|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | 0x03FF | Unassigned ONU-ID. | +| 3 | 0x01 | Message type ID "Serial_Number_ONU". | +| 4 | 0x00 | Sequence number. | +| 5-8 | Vendor_ID | The code set for the Vendor_ID is specified in [ATIS-0300220].
The four characters are mapped into the 4-byte field by taking each ASCII/ANSI character code and concatenating them.
Example: Vendor_ID = ABCD → Byte 5 = 0x41, Byte 6 = 0x42, Byte 7 = 0x43, Byte 8 = 0x44. | +| 9-12 | VSSN | Vendor-specific serial number. | +| 13-16 | Random_delay | The random delay used by the ONU when sending this message, measured in bit times with respect to the nominal upstream line rate of 2.48832 Gbit/s. | +| 17-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check computed using the default PLOAM integrity key (see clause 15.8). | + +#### 11.3.4.2 Registration message + +| Octet | Content | Description | +|-------|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Sender identity | +| 3 | 0x02 | Message type ID "Registration". | +| 4 | SeqNo | Repeated from downstream Request_Registration message, or 0 if generated in response to a ranging grant in the Ranging state (O4). | +| 5-40 | Registration_ID | A string of 36 octets that may be useful in identifying a particular ONU installed at a particular location. The default is a string of 0x00 octets (Note). | +| 41-48 | MIC | Message integrity check computed using the default PLOAM integrity key (see clause 15.8). | + +NOTE – It is recommended that the Registration\_ID be a string of ASCII characters, justified in the lower-numbered bytes of the registration message, and with 0x00 values in unused byte positions. + +#### 11.3.4.3 Key\_Report message + +| Octet | Content | Description | +|-------|--------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Sender identity | +| 3 | 0x05 | Message type ID "Key_Report". | +| 4 | SeqNo | Repeats value from the downstream Key_Control message. If the length of the keying material requires that several Key_Report messages be sent upstream, the sequence number is the same in each of them. | +| 5 | 0000 000R | Report type.
R: 0-NewKey: The message contains the newly generated key or key fragment
1-ExistingKey: The message contains the cryptographic hash of an existing key. | +| 6 | 0000 00bb | bb: Key index
01-First key of a key pair.
10-Second key of a key pair. | +| 7 | 0000 0FFF | Fragment number, range 0..7. The first fragment is number 0 (Note). | +| 8 | Reserved | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 9-40 | Key_Fragment | Key fragment, 32 bytes. Any padding that may be required is in the higher-numbered bytes of the message.
To confirm the existing key, a single 16-byte fragment containing the cryptographic hash of the key (key name) is sent.
Key_Name = AES_CMAC (KEK, encryption_key 0x33313431353932363533353839373933, 128).
For a new key, KEK_encrypted key fragment is sent.
KEK_Encrypted_key = AES_ECB (KEK, encryption_key).
(Note) | +| 41-48 | MIC | Message integrity check. | + +NOTE – This parameter supports the long-term extensibility of the data encryption key exchange protocol. Both the currently specified (see clause 15.4) cryptographic method for the data encryption (AES-128) and its immediate extension (AES-192 or AES-256) require a single key fragment and only one Key\_Report PLOAM message to transmit the key. + +#### 11.3.4.4 Acknowledgment message + +| Octet | Content | Description | +|-------|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | ONU-ID | Sender identity | +| 3 | 0x09 | Message Type ID: "Acknowledgement". | +| 4 | SeqNo | Same as downstream sequence number. If the ONU has no upstream message to send (keep-alive grant from OLT), it sets the upstream sequence number to 0. | + +| Octet | Content | Description | +|-------|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 5 | Completion_code | 0-OK
1-No message to send.
2-Busy, preparing a response.
3-Unknown message type.
4-Parameter error.
5-Processing error.
Other values reserved. | +| 6-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +#### 11.3.4.5 Sleep\_Request message + +An ONU sends Sleep\_Request to signal its intention to start or terminate power saving. Clause 16 defines the use and function of this message in detail. + +| Octet | Content | Description | +|-------|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | ONU-ID | Sender identity | +| 3 | 0x10 | Message type ID "Sleep_Request". | +| 4 | SeqNo | Always 0. | +| 5 | Activity_level | 0: Sleep_Request (Awake).
Non-zero values of the parameter indicate a request to initiate a specific power management mode: ONU alternates between an Aware state (SleepAware, DozeAware, or WatchAware), when the ONU receives and transmits traffic, and a corresponding LowPower state (Asleep, Listen, or Watch), when the ONU does not transmit upstream.
1: Sleep_Request (Doze). Doze mode request: when in a LowPower state (the Listen state) the ONU receiver remains active, the ONU can receive downstream traffic.
2: Sleep_Request (Sleep). Cyclic sleep mode request: when in a LowPower state (the Asleep state), the ONU receiver is inactive; the ONU cannot receive downstream traffic.
3: Sleep_Request (WSleep). Watchful sleep mode request: when in a LowPower state (the Watch state), the ONU periodically checks the downstream traffic for wakeup indications from the OLT.
Other values reserved. | +| 6-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check | + +# 12 ONU activation + +## 12.1 Overview + +### 12.1.1 Definitions + +The term "activation process" refers to the set of distributed procedures allowing an inactive ONU to join or resume operations on the PON. + +The time interval at the OLT between transmission of a downstream PHY frame and the earliest possible reception of a corresponding PHY upstream burst from the given ONU is referred to as the ONU's round-trip delay (RTD). The RTD is composed of the round-trip propagation delay, which is proportional to the ONU's fibre distance, and the ONU response time. The RTDs vary from one ONU to another. In order to ensure that the bursts from different ONUs are aligned at the boundaries of the same upstream PHY frame, each given ONU has to delay the transmission of an upstream burst beyond its regular response time. This extra time is referred to as the ONU's equalization delay (EqD). The EqD for each given ONU is computed by the OLT based on measurement of the corresponding RTD. + +To avoid collisions with the regular upstream bursts during serial number acquisition and ranging of newly joining ONUs, the OLT must temporarily suppress upstream transmission by the in-service ONUs for the duration of the time interval when an arrival of an upstream burst from a new ONU can be expected. Such a time interval is referred to as a quiet window. + +The activation process includes three phases: synchronization, serial number acquisition, and ranging. + +During the synchronization phase, the ONU, while remaining passive, initializes a local instance of the downstream synchronization state machine and attains synchronization to the downstream PHY frames. + +During the serial number acquisition phase, the ONU starts learning the burst profile parameters to be used for upstream transmission. The ONU announces its presence on the PON by responding to serial number grants. A serial number grant is an allocation structure that is addressed to the broadcast Alloc-ID and has the PLOAMu flag set. The OLT discovers a new ONU by its serial number and assigns a unique ONU-ID to the ONU. + +During the ranging phase, the ONU responds to directed ranging grants. A ranging grant is an allocation structure that is addressed to the default Alloc-ID of the ONU and has the PLOAMu flag set. The OLT performs round-trip delay measurements, computes the equalization delay, and communicates it to the ONU. + +### 12.1.2 Causal sequence of activation events + +The OLT controls the ONU activation process by means of issuing function-specific bandwidth grants and exchanging upstream and downstream PLOAM messages. The outline of the activation process events in their causal order is given below: + +- The ONU entering the activation process listens to the downstream transmission and attains PSync and superframe synchronization. +- The ONU listens to the Profile PLOAM messages, periodically issued by the OLT, to start learning the burst profiles specified for upstream transmission. +- Once the ONU receives a serial number grant with a known profile, it announces its presence on the PON with a Serial\_Number\_ONU PLOAM message. +- The OLT discovers the serial number of a newly connected ONU and assigns an ONU-ID to it using the Assign\_ONU-ID message. +- The OLT optionally issues a directed ranging grant to a newly discovered ONU and prepares to accurately measure the response time. +- The ONU responds with the Registration PLOAM message. +- The OLT performs initial authentication of the ONU based on the registration ID, computes the individual equalization delay and communicates this equalization delay to the ONU using the Ranging\_Time PLOAM message. +- The ONU adjusts the start of its upstream PHY frame clock based on its assigned equalization delay. + +- The ONU completes activation and starts regular operation. + +For the ONUs in regular operation, the OLT monitors the phase and the BER of the arriving upstream transmissions. Based on the monitored phase information, the OLT may re-compute and dynamically update the equalization delay for any ONU. + +## 12.2 Activation mechanism at the ONU + +### 12.2.1 ONU activation states, timers and counters + +Six ONU activation states are defined: + +- O1 – Initial state +- O2-3 – Serial Number state +- O4 – Ranging state +- O5 – Operation state +- O6 – Intermittent LODS state +- O7 – Emergency Stop state + +To support the activation procedure, the ONU maintains two timers: + +- TO1 Ranging timer. Timer TO1 is used to abort an unsuccessful activation attempt by limiting the overall time an ONU can remain in the Ranging state (O4). The recommended initial value of TO1 is 10 seconds. +- TO2 Loss of downstream synchronization (LODS) timer. Timer TO2 is used to assert a failure to recover from an intermittent LODS condition by limiting the time an ONU can remain in the Intermittent LODS state (O6). The recommended initial value of TO2 is 100 ms. + +In addition, the ONU may, at its discretion, maintain a dedicated timer to mitigate the Forgotten ONU condition, whereby the ONU accidentally remains in O5 state while no longer being accounted for by the OLT. + +- TOF Forgotten ONU timer. Timer TOF allows the ONU in the Operation state (O5) to reactivate itself when it is no longer accounted for by the OLT. Timer TOF is initialized upon a transition into the Operation state (O5) from the Ranging state (O4) and is reset every time the ONU receives a directed allocation of any type. Upon transition from the Operation state (O5) to the Intermittent LODS state (O6), timer TOF is stopped, but is not reset. If the ONU returns to the Operation state (O5), it resumes timer TOF from its stopped value. Upon timer TOF expiration, the ONU executes a transition into Initial state (O1). Timer TOF is an autonomously maintained safety feature, which is excluded from the further discussion of the state machine. Its suggested initial value is 10 s. + +### 12.2.2 ONU activation state specification + +The semantics of the ONU activation states is defined as follows: + +#### a) Initial state (O1) + +The ONU originally powers up in this state and enters this state upon ONU deactivation or enabling after an emergency stop. The transmitter is turned off. The TC layer configuration parameters, including ONU-ID, default and explicitly assigned Alloc-IDs, default XGEM Port-ID, burst profiles, and equalization delay, as well as the MSK and the derived shared keys, are discarded. The ONU synchronization state machine (see clause 10.1.2) is initialized. Once synchronization to the downstream PHY frame is attained, the ONU moves to the Serial\_Number state (O2-3). + +#### b) **Serial\_Number state (O2-3)** + +The ONU activates its transmitter for burst mode behaviour under OLT control. The ONU parses the PLOAM partition of downstream XGTC frames and starts learning the burst profiles specified by the Profile PLOAM messages. If the ONU receives a serial number grant with a known burst profile, it responds with an XGTC frame containing an XGTC header carrying a Serial\_Number\_ONU PLOAM message and an XGTC trailer. When responding to a serial number grant, the ONU ignores the values of the DBRu flag and GrantSize field of the allocation structure. Once the ONU receives an Assign\_ONU-ID PLOAM message with its own serial number, it sets the ONU-ID along with the default Alloc-ID and OMCC XGEM Port-ID and transitions to the Ranging state (O4). Upon receipt of a Disable\_Serial\_Number PLOAM message for either its own serial number or all ONUs, the ONU transitions to the Emergency Stop state (O7). + +If the OLT already knows the ONU, which is returning to the PON, for example, during recovery from loss of power, it is possible that the OLT issues an Assign\_ONU-ID message to the ONU's known serial number. In this case, the ONU could move through the Serial\_Number state (O2-3) into the Ranging state (O4) without ever having responded to a serial number grant. + +#### c) **Ranging state (O4)** + +While awaiting the assignment of equalization delay by the OLT, the ONU responds to the directed ranging grants. If the ONU receives a ranging grant with a known burst profile, it transmits an XGTC frame containing an XGTC header carrying a Registration PLOAM message and an XGTC trailer. The ONU ignores the values of the DBRu flag and GrantSize field of the ranging grant allocation structure. The ONU parses the PLOAM partition of downstream XGTC frames reacting exclusively to the following PLOAM message types: Profile (directed or broadcast), Ranging\_Time (directed with absolute parameter), Deactivate\_ONU-ID (directed or broadcast), Disable\_Serial\_Number (broadcast for either the ONU's own serial number or all ONUs). Once the ONU receives the Ranging\_Time message with absolute equalization delay, it moves to the Operation state (O5). If timer TO1 expires while in state O4, the ONU discards the assigned ONU-ID value along with default Alloc-ID and default OMCI XGEM port-ID and transitions to the Serial Number state (O2-3), while keeping the learned burst profile information. + +If the OLT has previously measured the ONU's round-trip delay during the serial number acquisition, or during earlier activations of the ONU, it is possible that the OLT issues a Ranging\_Time message with the previously calculated equalization delay. In this case, the ONU could move through the Ranging state (O4) into the Operation state (O5) without having responded to a ranging grant. + +#### d) **Operation state (O5)** + +The ONU transmits upstream data and PLOAM messages as directed by the OLT. While in this state, the OLT can establish additional connections with the ONU as required. Once the network is ranged, and all ONUs are working with their correct equalization delays, all upstream bursts will be synchronized together between all the ONUs. Upstream transmissions arrive separately, each one in its correct location within the upstream PHY frame. + +At any time while the ONU is in state O5, the OLT may optionally initiate a secure mutual authentication procedure by one of the available methods. Secure mutual authentication does not require an extra activation state and is solely at the OLT's discretion. If the OLT chooses to perform secure mutual authentication, then prior to completion of the first execution of the procedure upon ONU activation, the OLT limits the transmitted downstream traffic and granted upstream allocations to the needs of the authentication procedure. + +#### e) **Intermittent LODS state (O6)** + +The ONU enters this state from the Operation state (O5) following the loss of downstream synchronization. Upon entry to the Intermittent LODS state (O6), the ONU starts timer TO2. If the downstream signal is re-acquired before TO2 expires, the ONU transitions back into the Operation state (O5). If the timer expires, the ONU moves to the initial state (O1). + +This method of handling an intermittent LODS condition assumes that any protection switching event in the network involving one and the same ONU interface is either under OLT control and, therefore, upon switchover the OLT can take appropriate steps to adjust the equalization delays for the involved ONUs, or the equalization delays for the primary and switchover paths are statically equalized within the accepted drift limits by inserting the appropriate lengths of fibre into the shorter of the two paths. + +#### f) **Emergency Stop state (O7)** + +An ONU that receives a Disable\_Serial\_Number message with the 'disable' option moves to the Emergency Stop state (O7) and shuts its laser off. The TC layer configuration parameters, including ONU-ID, default and explicitly assigned Alloc-IDs, default XGEM Port-ID, burst profiles, and equalization delay, as well as the MSK and the derived shared keys, are effectively discarded. + +When in the Emergency Stop state, the ONU keeps the downstream synchronization state machine running and parses the PLOAM partition of downstream XGTC frames, but is prohibited from forwarding data in the downstream direction or sending data in the upstream direction. + +When the reason to have the ONU disabled is cleared, the OLT may re-enable the ONU in order to bring it back to regular operation. The OLT re-enables an ONU in the Emergency\_Stop state by sending a Disable\_Serial\_Number PLOAM message with the 'enable' option. As a result, the ONU returns to the initial state (O1). + +The Emergency Stop state should persist over ONU reboot and power cycle. + +### 12.2.3 ONU state diagram + +Figure 12-1 shows a graphic representation of the six states of the ONU with major input events and associated state transitions. + +![Figure 12-1 – ONU activation state diagram. A state transition diagram showing seven states: Initial state (O1), Serial_Number state (O2-3), Ranging state (O4), Operation state (O5), Intermittent LODS state (O6), and Emergency Stop state (O7). Transitions are triggered by events like 'Downstream synchronization attained', 'Broadcast Deactivate ONU-ID request', 'Disable SN request', 'Assign_ONU-ID PLOAM', 'TO1 timer expires', 'Ranging_Time PLOAM', 'Equalization delay assigned', 'Loss of downstream synchronization', 'Downstream synchronization restored', 'TO2 timer expires', and 'Enable SN request'.](352d21d1e740e4a58cb17ab8656cfad8_img.jpg) + +``` + +stateDiagram-v2 + [*] --> O1: Initial state (O1) + + O1 --> O2_3: Downstream synchronization attained + + O2_3 --> O1: Broadcast Deactivate ONU-ID request + + O2_3 --> O2_3: Disable SN request + + O2_3 --> O4: Assign_ONU-ID PLOAM + + O4 --> O1: TO1 timer expires + + O4 --> O2_3: Disable SN request + + O4 --> O5: Ranging_Time PLOAM, Equalization delay assigned + + O5 --> O1: Disable SN request + + O5 --> O6: Loss of downstream synchronization + + O6 --> O1: Downstream synchronization restored + + O6 --> O2_3: Disable SN request + + O6 --> O5: TO2 timer expires + + O6 --> O7: Enable SN request + +``` + +Figure 12-1 – ONU activation state diagram. A state transition diagram showing seven states: Initial state (O1), Serial\_Number state (O2-3), Ranging state (O4), Operation state (O5), Intermittent LODS state (O6), and Emergency Stop state (O7). Transitions are triggered by events like 'Downstream synchronization attained', 'Broadcast Deactivate ONU-ID request', 'Disable SN request', 'Assign\_ONU-ID PLOAM', 'TO1 timer expires', 'Ranging\_Time PLOAM', 'Equalization delay assigned', 'Loss of downstream synchronization', 'Downstream synchronization restored', 'TO2 timer expires', and 'Enable SN request'. + +C.987.3(10)\_F12-1 + +Figure 12-1 – ONU activation state diagram + +### 12.2.4 ONU state transition table + +Table 12-1 is more detailed than the state diagram of clause 12.2.3. In Table 12-1, a dash within a cell indicates that the event is not applicable or is not recognized in the given state. + +Table 12-1 – ONU activation state transition table + +| Event | ONU activation state | | | | | | +|--------------------------------------------------------------------|----------------------|--------------------|------------|--------------|----------------------|-------------------| +| | Initial O1 | Serial Number O2-3 | Ranging O4 | Operation O5 | Intermittent LODS O6 | Emergency Stop O7 | +| Power up
If last operational state was O7 ==> O7
else ==> O1 | – | – | – | – | – | – | +| Downstream synchronization attained (LODS cleared) | ==> O2-3; | – | – | – | Stop TO2; ==> O5; | – | + +**Table 12-1 – ONU activation state transition table** + +| Event | ONU activation state | | | | | | +|-------------------------------------------|----------------------|-----------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------|-------------------| +| | Initial O1 | Serial Number O2-3 | Ranging O4 | Operation O5 | Intermittent LODS O6 | Emergency Stop O7 | +| Loss of downstream synchronization (LODS) | – | ==> O1; | Discard ONU-ID, default Alloc-ID, OMCI (default) XGEM Port-ID, and burst profiles; Stop TO1; ==> O1; | Start TO2; ==> O6; | – | – | +| Receive broadcast Profile PLOAM | – | Store the new profile; | Store the new profile; | Store the new profile; | – | – | +| Receive unicast Profile PLOAM | – | – | Store the new profile; | Store the new profile; Send ACK; | – | – | +| Receive broadcast Serial Number grant | – | If grant profile is known, send Serial_Number_ONU PLOAM; | – | – | – | – | +| Receive Assign ONU ID PLOAM (SN match) | – | Set ONU-ID, default Alloc-ID, and OMCI (default) XGEM Port-ID; Start TO1; ==> O4; | If consistent ONU-ID is being assigned, Ignore; otherwise, { Discard ONU-ID, default Alloc-ID, OMCI (default) XGEM Port-ID, and burst profiles; Stop TO1; ==> O1; } | If consistent ONU-ID is being assigned, ignore; otherwise, { Discard ONU-ID, default and explicitly assigned Alloc-IDs, OMCI (default) XGEM Port-ID, burst profiles, and equalization delay; ==> O1; } | – | – | +| Receive Ranging grant | – | – | Send Registration PLOAM; | – | – | – | +| Receive directed Ranging time PLOAM | – | – | Relative time? Ignore; Absolute time? { Stop TO1; Set EqD value; Send ACK; ==> O5; } | Relative time? Adjust EqD value; Absolute time? Set EqD value; Send ACK; | – | – | +| Receive broadcast Ranging time PLOAM | – | – | – | Relative time? Adjust EqD value; Absolute time? Ignore; | – | – | +| TO1 expired | – | – | Discard ONU-ID, default Alloc-ID, and OMCI (default) XGEM Port-ID; Stop TO1; ==> O2-3; | – | – | – | + +**Table 12-1 – ONU activation state transition table** + +| Event | ONU activation state | | | | | | +|------------------------------------------------------------------------|----------------------|------------------------------------------|------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | Initial
O1 | Serial
Number
O2-3 | Ranging
O4 | Operation
O5 | Intermittent
LODS
O6 | Emergency
Stop
O7 | +| Receive directed
Deactivate ONU ID
PLOAM | – | – | Discard ONU-ID,
default Alloc-ID,
OMCI
(default)
XGEM
Port-ID,
and burst profiles;
Stop TO1;
==> O1; | Discard ONU-ID,
default and explicitly
assigned Alloc-IDs,
OMCI (default)
XGEM Port-ID,
burst profiles, and
equalization delay;
==> O1; | – | – | +| Receive broadcast
Deactivate ONU ID
PLOAM | – | Discard
burst
profiles;
==> O1; | Discard ONU-ID,
default Alloc-ID,
OMCI
(default)
XGEM
Port-ID,
and burst profiles;
Stop TO1;
==> O1; | Discard ONU-ID,
default and explicitly
assigned Alloc-IDs,
OMCI (default)
XGEM Port-ID,
burst profiles, and
equalization delay;
==> O1; | – | – | +| Receive Disable
PLOAM – Disable
specific SN option
(SN match) | – | Discard
burst
profiles;
==> O7; | Stop TO1;
==> O7; | ==> O7; | – | – | +| Receive Disable
PLOAM
– Disable All option | – | Discard
burst
profiles;
==> O7; | Stop TO1;
==> O7; | ==> O7; | – | – | +| Receive Disable
PLOAM – Enable
specific SN option
(SN match) | – | – | – | – | – | Discard ONU-
ID, default and
explicitly
assigned
Alloc-IDs,
OMCI (default)
XGEM Port-ID,
burst profiles,
and equalization
delay;
==> O1; | +| Receive Disable
PLOAM
– Enable All option | – | – | – | – | – | Discard ONU-
ID, default and
explicitly
assigned
Alloc-IDs,
OMCI (default)
XGEM Port-ID,
burst profiles,
and equalization
delay;
==> O1; | +| TO2 expired | – | – | – | – | Discard
ONU-ID,
default and
explicitly
assigned
Alloc-IDs,
OMCI
(default)
XGEM Port-
ID, burst
profiles, and
equalization
delay;
==> O1; | – | + +**Table 12-1 – ONU activation state transition table** + +| Event | ONU activation state | | | | | | +|----------------------------------------------|----------------------|--------------------------|-----------------------------------------------|------------------------------------------------------------------|----------------------------|-------------------------| +| | Initial
O1 | Serial
Number
O2-3 | Ranging
O4 | Operation
O5 | Intermittent
LODS
O6 | Emergency
Stop
O7 | +| Receive bandwidth grant with data allocation | – | – | (Default Alloc-ID)
Ignore data allocation; | (Default or explicitly assigned Alloc-ID)
Transmit a burst; | – | – | +| Receive directed PLOAM grant | – | – | Send Registration PLOAM; | If ONU has a PLOAM to transmit,
Send PLOAM;
else Send ACK; | – | – | +| Receive Request_Registration PLOAM | – | – | – | Send Registration PLOAM; | – | – | +| Receive Assign Alloc ID PLOAM | – | – | – | Configure Alloc ID;
Send ACK; | – | – | +| Receive Key Control PLOAM | – | – | – | Subject to ONU key management state-machine | – | – | +| Receive Sleep Allow PLOAM | – | – | – | Subject to ONU power-management state-machine | – | – | + +NOTE – In this table, the "Send ACK" action in response to a receive event of a downstream PLOAM message means that an upstream PLOAM is generated and placed into a queue for upstream transmission. The ONU actually transmits a message from its upstream PLOAM queue when the OLT provides a PLOAMu grant. + +## 12.3 OLT support of the activation process + +To allow ONUs to join or resume operations on the PON, the OLT regularly issues serial number grants. The serial number grants are addressed to the broadcast Alloc-ID, carry a commonly known broadcast burst profile and have the PLOAMu flag set. The serial number grants should have the DBRu flag reset, carry the GrantSize of 0 and be accompanied by an appropriate quiet window. The frequency of serial number grants can be modulated by operational considerations, including pending ONU installations and the knowledge of temporarily inactive or failed ONUs. + +Once the OLT discovers an ONU that is willing to join or resume operations on the PON, it performs ONU-ID assignment and may issue directed ranging grants to that ONU in order to measure its round-trip delay. The ranging grants are addressed to the default Alloc-ID of an ONU in the ranging state, carry a burst profile that has been previously communicated to the ONU, and have the PLOAMu flag set. The ranging grants should have the DBRu flag reset, carry the GrantSize of 0 and be accompanied by the appropriate quiet window. In some cases, for example, after a loss of power or a protection switching event, the OLT may assign ONU-IDs and issue ranging grants to the known ONUs without explicitly rediscovering their serial numbers. In deciding on the size of the quiet window to accompany a ranging grant, the OLT may use the ranging information obtained from the serial number response, during the previous activations of the ONU or, in case of a protected optical distribution network (ODN), over an alternative ODN path. + +When the ONU is in the Operation state, the OLT may use any grant to that ONU to perform in-service round-trip delay measurement and equalization delay adjustment. + +The OLT at its discretion may deactivate a previously assigned ONU-ID, forcing the ONU to discard all TC layer configuration information and re-enter the activation process, or disable a specific serial number forcing that ONU into the Emergency Stop state and inhibiting any upstream transmissions or state transitions by that ONU until an explicit permission in the future. + +The OLT may use equalization delay readjustment, ONU-ID deactivation and serial number disabling for the purposes of rogue ONU prevention, detection and isolation. In an extreme situation when rogue behaviour is exhibited by an ONU that has not been able to declare its serial number, the OLT + +may globally disable all the ONUs on the PON and subsequently re-enable the conformant ONUs one-by-one. + +# 13 OLT and ONU timing relationships + +## 13.1 ONU transmission timing and equalization delay + +The material presented in this clause is based on the following definitions: + +- 1) The start of the downstream PHY frame is the moment of transmission/reception of the first bit of the PSync field. +- 2) The reference start time of an upstream PHY burst is the moment of transmission/reception of the first bit of the word identified by the StartTime of the corresponding bandwidth allocation structure. This is the first bit of the XGTC burst header. +- 3) The start of the upstream PHY frame is the moment of transmission/reception (either actual or calculated) of the first bit of the word that, if present, would be identified by the StartTime pointer of zero value. +- 4) The quiet window offset at the OLT is the elapsed time between the start of the downstream PHY frame in which the serial number grant or ranging grant is transmitted and the earliest possible start of an upstream PHY burst carrying the response PLOAM. +- 5) The upstream PHY frame offset at the OLT, $T_{eqd}$ , is the elapsed time between the start of the downstream PHY frame carrying a specific BWmap and the upstream PHY frame implementing that BWmap2. + +An ODN can be characterized by two parameters: the minimum fibre distance; $L_{min}$ , and the maximum differential fibre distance, $D_{max}$ . These parameters are expressed in kilometres, are fixed by ODN design and are known to the OLT *a priori*. The fibre distance $L_i$ , of ONU *i* satisfies: + +$$L_{min} \leq L_i \leq L_{min} + D_{max} \quad (13-1)$$ + +### 13.1.1 Timing of ONU upstream transmissions + +All ONU transmission events are referenced to the start of the downstream PHY frame carrying the BWmap that contains the corresponding burst allocation series. Note, in particular, that an ONU transmission event is not referenced to the receipt of the corresponding burst allocation series itself, which may occur at a variable time into the downstream PHY frame. + +At all times, the ONU maintains a running upstream PHY frame clock that is synchronized to the downstream PHY frame clock and offset by a precise amount. The amount of offset is the sum of two values: the ONU response time and the requisite delay, as shown in Figure 13-1. + +--- + +2 In [b-ITU-T G.984.3], this parameter is referred to as a zero-distance equalization delay. + +![Figure 13-1 – ONU timing diagram – General case. This diagram shows the timing relationship between an OLT and an ONU. At the OLT, a 'Start of the DS PHY frame in OLT's view' marks the beginning of a frame containing 'PSBd', 'PSync', and 'Downstream PHY frame content'. A diagonal line shows the frame propagating to the ONU. At the ONU, the 'Start of DS PHY frame in ONU's view' is marked. The ONU then sends a response, and the 'Start of the US PHY frame in ONU's view (StartTime = 0)' is marked. The ONU's response frame contains 'PSBu' and 'PHY burst content'. A diagonal line shows this frame propagating back to the OLT, where it is labeled as the 'Upstream PHY burst'. Various time intervals are indicated: 'Propagation delay' (OLT to ONU and ONU to OLT), 'ONU response time', 'Requisite delay', and 'StartTime'.](6a7ea9d5162b0a0cfbd8d77c6cac90d1_img.jpg) + +Figure 13-1 – ONU timing diagram – General case. This diagram shows the timing relationship between an OLT and an ONU. At the OLT, a 'Start of the DS PHY frame in OLT's view' marks the beginning of a frame containing 'PSBd', 'PSync', and 'Downstream PHY frame content'. A diagonal line shows the frame propagating to the ONU. At the ONU, the 'Start of DS PHY frame in ONU's view' is marked. The ONU then sends a response, and the 'Start of the US PHY frame in ONU's view (StartTime = 0)' is marked. The ONU's response frame contains 'PSBu' and 'PHY burst content'. A diagonal line shows this frame propagating back to the OLT, where it is labeled as the 'Upstream PHY burst'. Various time intervals are indicated: 'Propagation delay' (OLT to ONU and ONU to OLT), 'ONU response time', 'Requisite delay', and 'StartTime'. + +**Figure 13-1 – ONU timing diagram – General case** + +The range of ONU response time is a system-wide parameter that is chosen to give the ONU sufficient time to receive the downstream frame, including the upstream bandwidth map, perform downstream and upstream FEC as needed, and prepare an upstream response. All ONUs are required to have an ONU response time of $35 \pm 1 \mu\text{s}$ . Further, the ONU is required to know its response time. + +The general term "requisite delay" refers to the total extra delay that an ONU may be required to apply to the upstream transmission beyond its regular response time. The purpose of the requisite delay is to compensate for variation of propagation and processing delays of individual ONUs, and to avoid or reduce the probability of collisions between upstream transmissions. The value of requisite delay changes with the state of the ONU is described below. + +### 13.1.2 Timing relationships and quiet window during serial number acquisition + +The timing relationships and quiet window during serial number acquisition are illustrated in Figure 13-2. + +![Figure 13-2 – Timing relationships during serial number acquisition. This diagram illustrates the timing for serial number acquisition. The OLT sends a 'SN Grant' (Alloc-ID = 1023, StartTime = S, GrantSize = 0) within a 'PHY frame content'. The ONU receives this and responds with a 'Serial_Number ONU PLOAM' message. The diagram shows the 'Earliest expected Serial_Number PLOAM' and 'Latest expected Serial_Number PLOAM' at the OLT. A 'Quiet window' is defined between these two expected times. Timing parameters include 'RspTime_min', 'StartTime', 'T1577,i', 'RspTime_i', 'Rand_i', 'StartTime', and 'T1270,i'. The ONU's response frame contains 'PSBu' and 'PLOAM'.](6707cae4df136f92a0c9f3a4676f91a6_img.jpg) + +Figure 13-2 – Timing relationships during serial number acquisition. This diagram illustrates the timing for serial number acquisition. The OLT sends a 'SN Grant' (Alloc-ID = 1023, StartTime = S, GrantSize = 0) within a 'PHY frame content'. The ONU receives this and responds with a 'Serial\_Number ONU PLOAM' message. The diagram shows the 'Earliest expected Serial\_Number PLOAM' and 'Latest expected Serial\_Number PLOAM' at the OLT. A 'Quiet window' is defined between these two expected times. Timing parameters include 'RspTime\_min', 'StartTime', 'T1577,i', 'RspTime\_i', 'Rand\_i', 'StartTime', and 'T1270,i'. The ONU's response frame contains 'PSBu' and 'PLOAM'. + +**Figure 13-2 – Timing relationships during serial number acquisition** + +An ONU enters the Serial\_Number state (O2-3) upon attaining synchronization to the downstream PHY frames in the course of activation. When an ONU in this state receives a serial number grant, it transmits a serial number response in the form of a Serial\_Number\_ONU PLOAM message. + +To avoid collisions between a serial number response from an ONU in the Serial\_Number state and the regular upstream bursts from the ONUs in the Operation state, the OLT opens a quiet window to temporarily suppress upstream transmission by the in-service ONUs. + +Since the serial number grant is a broadcast bandwidth allocation addressed to all ONUs in the Serial\_Number state, more than a single ONU may respond to it, and a collision may occur when more than one serial number response arrives at the OLT at the same time. To reduce the probability of collision, the requisite delay in the Serial\_Number state is a locally-generated random delay. The random delay has a range of 0-48 $\mu\text{s}$ and is expressed in bit times with respect to the nominal upstream line rate of 2.48832 Gbit/s. For each response to a serial number grant, the ONU generates a new random delay. + +The offset of the quiet window during serial number acquisition is determined by the minimum delays in the system, including the minimum round-trip propagation delay and minimum ONU processing time, as well as the dynamically generated StartTime value of the serial number grant: + +$$W_0^{SN} = RspTime_{\min} + \frac{L_{\min} (n_{1577} + n_{1270})}{c} + \frac{StartTime}{R_{\text{nom}}} \quad (13-2)$$ + +Here $c$ is the speed of light in km/ $\mu\text{s}$ , and $R_{\text{nom}}$ is the nominal upstream line rate in words/ $\mu\text{s}$ . + +The size of the quiet window during serial number acquisition is determined by the maximum variation of the unknown round-trip delay components and the duration of the serial number response burst. The unknown round-trip delay components include round-trip propagation delay, ONU response time, and ONU random delay. The serial number response burst includes preamble, delimiter, XGTC header with a Serial\_Number\_ONU PLOAM message, and XGTC trailer. + +$$W_{\Delta}^{SN} = RspTime_{\text{var}} + \frac{D_{\max} (n_{1577} + n_{1270})}{c} + Rand_{\max} + \frac{BurstSize}{R_{\text{nom}}} \quad (13-3)$$ + +The duration of the serial number response burst (typically, less than 0.3 $\mu\text{s}$ ) is negligible compared with the other components. + +For an ODN with a differential fibre distance of 20 km, the values are: + +- 200 $\mu\text{s}$ for the variation of round-trip propagation delay; +- 2 $\mu\text{s}$ for the variation of ONU response time; +- 48 $\mu\text{s}$ for the ONU's maximum random delay. + +The suggested duration of the quiet window during serial number acquisition is 250 $\mu\text{s}$ . + +For an ODN with a differential fibre distance of 40 km, the values are: + +- 400 $\mu\text{s}$ for the variation of round-trip propagation delay; +- 2 $\mu\text{s}$ for the variation of ONU response time; +- 48 $\mu\text{s}$ for the ONU's maximum random delay. + +The suggested duration of the quiet window during serial number acquisition is 450 $\mu\text{s}$ . + +### 13.1.3 Timing relationships and quiet window during ranging + +The timing relationships and quiet window during ranging are illustrated in Figure 13-3. + +![Figure 13-3 – Timing relationships during ranging. The diagram shows the interaction between an OLT and an ONU. The OLT sends a Ranging Grant (Alloc-ID = ONU-ID, StartTime = S, GrantSize = 0) to the ONU. The ONU responds with a Registration PLOAM message. The OLT defines a 'Quiet window' to suppress other upstream traffic. Timing parameters shown include RspTime_min, StartTime, PSBd, PHY frame content, PSBu, PLOAM, T_1577,i, RspTime_i, and T_1270,i. The diagram is labeled G.987.3(25).](a4de02b04a1a8f6cb8121ac2e11bf95a_img.jpg) + +Figure 13-3 – Timing relationships during ranging. The diagram shows the interaction between an OLT and an ONU. The OLT sends a Ranging Grant (Alloc-ID = ONU-ID, StartTime = S, GrantSize = 0) to the ONU. The ONU responds with a Registration PLOAM message. The OLT defines a 'Quiet window' to suppress other upstream traffic. Timing parameters shown include RspTime\_min, StartTime, PSBd, PHY frame content, PSBu, PLOAM, T\_1577,i, RspTime\_i, and T\_1270,i. The diagram is labeled G.987.3(25). + +**Figure 13-3 – Timing relationships during ranging** + +An ONU enters the Ranging state (O4) upon assignment of ONU-ID. While in the Ranging state, the ONU interprets any directed bandwidth allocation with the PLOAMu flag set as a ranging grant and responds to it with a Registration PLOAM message. + +To avoid collisions between the ranging grant response and the regular upstream bursts from the ONUs in the Operation state, the OLT opens a quiet window to temporarily suppress upstream transmission by the in-service ONUs. During ranging, the requisite delay is equal to zero. + +The offset of the quiet window during ranging is determined by the minimum round-trip propagation delay and minimum ONU processing time, as well as the dynamically generated StartTime value of the ranging grant: + +$$W_0^{RNG} = RspTime_{min} + \frac{L_{min}(n_{1577} + n_{1270})}{c} + \frac{StartTime}{R_{nom}} \quad (13-4)$$ + +The size of the quiet window during ranging is determined by the maximum variation of the unknown round-trip delay components and the duration of the registration burst. If the OLT has not already obtained a measure or estimate of the round-trip delay during serial number acquisition, the unknown round-trip delay components include round-trip propagation delay and ONU response time. The ranging response burst includes preamble, delimiter, XGTC header with a Registration PLOAM message, and XGTC trailer. + +$$W_{\Delta}^{RNG} = RspTime_{var} + \frac{D_{max}(n_{1577} + n_{1270})}{c} + \frac{BurstSize}{R_{nom}} \quad (13-5)$$ + +The duration of the ranging response burst (typically, less than 0.3 $\mu\text{s}$ ) is negligible compared with the other components. + +For an ODN with a differential fibre distance of 20 km, the values are: + +- 200 $\mu\text{s}$ for the variation of round-trip propagation delay; +- 2 $\mu\text{s}$ for the variation of ONU response time. + +The maximum suggested duration of the quiet window during ranging is 202 $\mu\text{s}$ . + +For an ODN with a differential fibre distance of 40 km, the values are: + +- 400 $\mu\text{s}$ for the variation of the round-trip propagation delay; +- 2 $\mu\text{s}$ for the variation of the ONU response time. + +The maximum suggested duration of the quiet window during ranging is 402 $\mu\text{s}$ . + +In practice, the maximum suggested values derived above may be reduced if the OLT makes use of the ranging information obtained from the serial number response, during the previous activations of the ONU or, in case of a protected ODN, over an alternative ODN path + +### 13.1.4 Calculating the equalization delay + +The OLT selects $T_{eqd}$ , the upstream PHY frame offset, based on the ODN design parameters: + +$$T_{eqd} \geq RspTime_{max} + (L_{min} + D_{max}) \frac{(n_{1577} + n_{1270})}{c} \quad (13-6)$$ + +The selected value of $T_{eqd}$ remains constant through the lifetime of the PON. + +When the OLT issues a ranging grant to an ONU in the Ranging state (O4), the OLT accurately measures the elapsed time $\Delta_i^{RNG}$ between the downstream PHY frame containing the ranging grant and the upstream PHY burst containing the response Registration PLOAM (see Figure 13-4). Given the selected upstream PHY frame offset, the equalization delay of the ONU is found as: + +$$EqD_i = T_{eqd} - RTD_i = T_{eqd} - \left( \Delta_i^{RNG} - \frac{StartTime}{R_{nom}} \right) \quad (13-7)$$ + +Alternatively, the OLT can measure the equalization delay directly by timing the duration between the actual and desired arrival times of the burst containing the Registration PLOAM message. + +The value of equalization delay calculated by the OLT and communicated to the ONU is accurate to a single bit time with respect to the nominal upstream line rate of 2.48832 Gbit/s. The ONU is required to maintain the granularity of the equalization delay adjustment of not more than 8-bit times. + +Once the ONU is supplied with its equalization delay value, it is considered synchronized to the beginning of the upstream PHY frame. The upstream data is transmitted within the interval specified by the allocation structure with respect to the beginning of the upstream PHY frame. + +![Figure 13-4 – Equalization delay calculation during ranging. This timing diagram illustrates the interaction between an OLT and an ONU for ranging. The OLT sends a 'Ranging Grant' (Alloc-ID = ONU-ID, StartTime = S, GrantSize = 0) in a downstream (DS) PHY frame. The ONU receives this and responds with a 'Registration PLOAM' in an upstream (US) PHY burst. The OLT measures the time Δ_i^RNG between the start of the DS frame and the start of the US burst. The ONU calculates the equalization delay EqD_i based on the received grant and its own timing. The diagram shows various time intervals: T_eqd (upstream PHY frame offset), RTD_i (round trip delay), Δ_i^RNG (elapsed time between DS frame and US burst), StartTime (start time of the ranging grant), T_1577,i (time from start of DS frame to start of US frame in ONU's view), RspTime_i (response time), and T_1270,i (time from start of US frame to desired reception of registration PLOAM).](1ae16a393229b439c7b3f8b2e63d8d6c_img.jpg) + +The diagram shows the timing sequence for equalization delay calculation during ranging. The OLT transmits a downstream (DS) PHY frame containing a Ranging Grant. The ONU receives this grant and responds with an upstream (US) PHY burst containing a Registration PLOAM. The OLT measures the elapsed time $\Delta_i^{RNG}$ between the start of the DS PHY frame and the start of the US PHY burst. The ONU calculates the equalization delay $EqD_i$ based on the received grant and its own timing. The diagram illustrates the following time intervals and components: + +- OLT:** Shows the transmission of a DS PHY frame (PSBd + PHY frame content) containing a Ranging Grant. The start of the DS PHY frame in the OLT's view is marked. The start of the US PHY frame in the OLT's view is also marked. The desired reception of the registration PLOAM is indicated. +- ONU:** Shows the reception of the DS PHY frame and the transmission of the US PHY burst (PSBu + PLOAM). The start of the DS PHY frame in the ONU's view is marked. The start of the US PHY frame in the ONU's view (StartTime = 0) is marked. The desired reception of the registration PLOAM is also indicated. +- Timing Intervals:** + - $T_{eqd}$ : Upstream PHY frame offset. + - $RTD_i$ : Round trip delay. + - $\Delta_i^{RNG}$ : Elapsed time between the start of the DS PHY frame and the start of the US PHY burst. + - $StartTime$ : Start time of the ranging grant. + - $T_{1577,i}$ : Time from the start of the DS PHY frame to the start of the US PHY frame in the ONU's view. + - $RspTime_i$ : Response time. + - $T_{1270,i}$ : Time from the start of the US PHY frame to the desired reception of the registration PLOAM. + +Figure 13-4 – Equalization delay calculation during ranging. This timing diagram illustrates the interaction between an OLT and an ONU for ranging. The OLT sends a 'Ranging Grant' (Alloc-ID = ONU-ID, StartTime = S, GrantSize = 0) in a downstream (DS) PHY frame. The ONU receives this and responds with a 'Registration PLOAM' in an upstream (US) PHY burst. The OLT measures the time Δ\_i^RNG between the start of the DS frame and the start of the US burst. The ONU calculates the equalization delay EqD\_i based on the received grant and its own timing. The diagram shows various time intervals: T\_eqd (upstream PHY frame offset), RTD\_i (round trip delay), Δ\_i^RNG (elapsed time between DS frame and US burst), StartTime (start time of the ranging grant), T\_1577,i (time from start of DS frame to start of US frame in ONU's view), RspTime\_i (response time), and T\_1270,i (time from start of US frame to desired reception of registration PLOAM). + +Figure 13-4 – Equalization delay calculation during ranging + +G.987.3(10)\_F13-4 + +### 13.1.5 Timing relationships during regular operation + +In the Operation state, the ONU maintains its upstream PHY frame clock synchronized with the downstream PHY frame clock and offset by the sum of the ONU response time and the assigned equalization delay specified by the OLT in the Ranging\_Time message, as shown in Figure 13-5. When the ONU receives a bandwidth allocation, it transmits data starting at the upstream word indicated in the StartTime field. During regular operation, the requisite delay is equal to the assigned equalization delay. + +![Figure 13-5: Timing relationships in the Operation state. The diagram shows two horizontal timelines: OLT and ONU. The OLT timeline shows downstream (DS) PHY frames with PSBd headers and PHY frame content. A 'BW Grant: StartTime = S' is sent from OLT to ONU. The ONU timeline shows the reception of the DS frame and the transmission of an upstream (US) PHY burst. Key timing intervals include: T_eqd (total equalization delay at OLT), StartTime (offset within the US frame), T_1577,i (DS propagation delay), RspTime_i (ONU response time), EqD_i (ONU equalization delay), and T_1270,i (US propagation delay). Arrows indicate the flow of frames and timing offsets between the OLT and ONU views.](c06fd7dbef68a8b788158f2081d9d734_img.jpg) + +Figure 13-5: Timing relationships in the Operation state. The diagram shows two horizontal timelines: OLT and ONU. The OLT timeline shows downstream (DS) PHY frames with PSBd headers and PHY frame content. A 'BW Grant: StartTime = S' is sent from OLT to ONU. The ONU timeline shows the reception of the DS frame and the transmission of an upstream (US) PHY burst. Key timing intervals include: T\_eqd (total equalization delay at OLT), StartTime (offset within the US frame), T\_1577,i (DS propagation delay), RspTime\_i (ONU response time), EqD\_i (ONU equalization delay), and T\_1270,i (US propagation delay). Arrows indicate the flow of frames and timing offsets between the OLT and ONU views. + +G.987.3(10)\_F13-5 + +**Figure 13-5 – Timing relationships in the Operation state** + +### 13.1.6 In-service equalization delay adjustment + +The OLT expects the ONU's upstream transmission to arrive at a fixed time during the upstream PHY frame. The arrival phase of the ONU transmission may drift due to aging, temperature changes and other factors. In those cases, the equalization delay can be recalculated and adjusted from the drift of the upstream transmission. In-service equalization delay adjustment allows small corrections to be made without having to re-range the ONU. + +The change in the equalization delay is equal to the drift time with the opposite sign. If the PHY burst arrives early, the OLT increases the equalization delay by the drift time. If the PHY burst arrives late, the OLT reduces the equalization delay by the drift time. Equalization delay adjustments are communicated to an ONU in the Operation state using the Ranging\_Time PLOAM message. A relative delay parameter can be conveniently used for this purpose. + +To avoid excessively frequent equalization delay adjustments and to ensure ONU compliance, the OLT maintains two drift thresholds applicable to all ONUs. The lower threshold establishes the safe bounds within which the transmission drift is considered acceptable and does not require any mitigating action. When the drift exceeds the lower threshold, the OLT calculates a new equalization delay value and transmits it to the ONU using the Ranging\_Time PLOAM message. The OLT also recognizes a drift of window (DOWi) event. The upper threshold establishes the critical bounds beyond which the transmission drift can affect the other ONUs on the PON. If the drift exceeds the upper threshold (an event which should not happen as long as the ONU complies with the equalization delay adjustments), the OLT declares transmission interference warning (TIWi) and takes further mitigating actions that may include deactivation or disabling of the offending ONU-ID, or execution of a rogue ONU diagnostic procedure. + +The suggested threshold values of DOWi and TIWi for the nominal upstream line rate of 2.48832 Gbit/s are $\pm 8$ bits and $\pm 16$ bits, respectively. + +### 13.1.7 Quiet window implementation considerations + +When in the Serial Number and Ranging states, the ONUs transmit Serial\_Number\_ONU PLOAM messages and Registration PLOAM messages. Because the OLT does not yet know the equalization delay for these ONUs, it opens a quiet window to prevent collision between the serial number or ranging responses and the regular upstream transmissions by in-service ONUs. + +Consider the example shown in Figure 13-6. Here $L_{min} = 0$ ; $D_{max} = 20$ km; $T_{eqd} = 236$ $\mu s$ . This example focuses on serial number acquisition and assumes that the propagation delay is bounded by 100 $\mu s$ while the ONU response time for different ONUs may vary, unbeknown to the OLT, within the $35 \pm 1$ $\mu s$ range. Therefore, if the OLT transmits a downstream PHY frame with a specific BWmap at time $t_0$ , coinciding with the start of downstream PHY frame $N$ , the earliest it can schedule the upstream PHY frame implementing this BWmap is 236 $\mu s$ later. The OLT's objective is to create a 250 $\mu s$ -long quiet window starting at time $t_q = t_0 + 236$ $\mu s$ . + +The BWmap supplied with downstream PHY frame $N$ is empty, while the sole allocation structure of the BWmap transmitted with downstream PHY frame $N + 1$ is a serial number grant with StartTime offset of 77 $\mu s$ , which corresponds to the upstream word value of 5989. The start of the possible serial number response transmission window is offset by at least 111 $\mu s$ with respect to the start of the frame carrying the serial number grant, and by at least 236 $\mu s$ , with respect to frame $N$ . + +Note that PHY frame $N - 1$ has to provide the necessary burst mode margin at the end of the BWmap. + +![Figure 13-6: Quiet window creation diagram. The diagram illustrates the timing relationship between OLT downstream PHY frames (N, N+1, N+2, N+3) and the upstream responses from a 'Farthest ONU'. Downstream frames are separated by PSBd blocks. Frame N contains an 'Empty BWMap'. Frame N+1 contains an 'SN Request: StartTime = 5989 (77 μs)'. A quiet window of 250 μs is established starting at time t_z (which is t_0 + T_eqd). The upstream timeline shows propagation delays (T_1577,i and T_1270,i) and response times (Rsp Time_max, Rsp Time_i). A 'Possible SN response transmission' window is shown spanning across the time corresponding to downstream frames N+2 and N+3. Key timing markers include T_eqd = 236 μs and an offset of 111 μs between the SN request and the start of the response window.](60a40901e77feeb97ab6cf9c6d9418c3_img.jpg) + +Figure 13-6: Quiet window creation diagram. The diagram illustrates the timing relationship between OLT downstream PHY frames (N, N+1, N+2, N+3) and the upstream responses from a 'Farthest ONU'. Downstream frames are separated by PSBd blocks. Frame N contains an 'Empty BWMap'. Frame N+1 contains an 'SN Request: StartTime = 5989 (77 μs)'. A quiet window of 250 μs is established starting at time t\_z (which is t\_0 + T\_eqd). The upstream timeline shows propagation delays (T\_1577,i and T\_1270,i) and response times (Rsp Time\_max, Rsp Time\_i). A 'Possible SN response transmission' window is shown spanning across the time corresponding to downstream frames N+2 and N+3. Key timing markers include T\_eqd = 236 μs and an offset of 111 μs between the SN request and the start of the response window. + +Figure 13-6 – Quiet window creation + +Since each such quiet window affects at least two and possibly three consecutive bandwidth maps, the OLT must ensure that the impact of the quiet windows on the bandwidth and jitter-sensitive traffic flows is minimized. This may be achieved, for example, by re-arranging the BWmaps and providing extra allocations to the affected Alloc-IDs immediately before and/or immediately after the quiet window. + +If some information about ONU locations is available to the OLT, it may be able to create a smaller, better targeted and less intrusive quiet window, whose offset with respect to the start of the downstream PHY frame depends on the fibre distance of the closest ONU, and whose size depends on the maximum differential fibre distance. + +### 13.1.8 Fibre distance measurement + +The OLT can estimate the fibre distance based on the round-trip measurement using $RspTime_i$ , the actual response time of ONU $i$ , which can be obtained via the OMCC. The estimate of the fibre distance between the OLT and the given ONU $i$ (in meters) may be obtained according to the following formula: + +$$FD_i = \left( RTT_i - RspTime_i - EqD_i - \frac{StartTime}{R_{nom}} \right) \times 102 \quad (13-8)$$ + +Here $RTT_i$ is the round-trip time, i.e., the actual offset of the start of the upstream PHY burst with respect to the start of the downstream PHY frame specifying that burst, in microseconds, as measured by the OLT; $RspTime_i$ is the true ONU response time in microseconds, as reported by ONU $i$ ; $EqD_i$ is the equalization delay of the ONU; $StartTime$ is the dynamically generated StartTime value of the burst when the measurement is conducted; $R_{nom}$ is the nominal upstream line rate in words/ $\mu\text{s}$ ; and the numeric coefficient of 102 m/ $\mu\text{s}$ is a best fit value reflecting the range of refractive indices that [ITU-T G.652] fibres exhibit in the field. This method is capable of producing an estimate that is approximately $\pm 1\%$ accurate. + +## 13.2 Time of day distribution over XG-PON + +This clause describes the TC layer method that is used to obtain the accurate time of day (ToD) at an XG-PON ONU, the timing relations between OLT and ONU, and the timing error analysis. The required accuracy of the ToD clock at the ONU is $\pm 1\mu\text{s}$ . Achieving better accuracy of the ONU's ToD clock is a topic of further study. + +The principle of operation is as follows. It is assumed that the OLT has an accurate real time clock, obtained through means beyond the scope of this Recommendation. The OLT informs the ONU of the time of day when a certain downstream PHY frame would arrive at a hypothetical ONU that had zero equalization delay and zero ONU response time. The certain downstream PHY frame is identified by $N$ , the value of its superframe counter, which is an existing feature of the protocol. The information transfer is accomplished using the OMCI channel, and does not need to be in real time. Having learned the ToD arrival time of frame $N$ , the ONU can use its equalization delay and response time to compute the ToD associated with the arrival of an arbitrary downstream PHY frame with very high accuracy. + +### 13.2.1 Notation + +**$Tstamp_N$** – This term refers to the exact ToD at which the first bit of downstream PHY frame $N$ arrives at a hypothetical ONU that has an EqD of zero and a response time of zero. The arrival of the signal at the ONU is defined to be the instant at which the optical signal crosses the optical connector or splice that is the boundary between the ODN and the ONU. + +**$Tsend_N$** – The exact ToD at which the first bit of downstream PHY frame $N$ departs from the OLT. The departure of the signal is defined to be the instant at which the optical signal crosses the optical connector or splice that is the boundary between the OLT and the ODN. + +**$Trecv_{N,i}$** – The exact ToD at which the first bit of downstream PHY frame $N$ arrives at ONU $i$ . The arrival of the signal at the ONU is defined to be the instant at which the optical signal crosses the optical connector or splice that is the boundary between the ODN and the ONU. + +**$RspTime_i$** – The value of the response time for ONU $i$ , which lies in the range of 34 to 36 microseconds. + +**$T_{eqd}$** – The offset of the upstream PHY frame with respect to the downstream PHY frame at the OLT location. The OLT adjusts the equalization delay of each ONU such that, for all ONUs, the start of the upstream frame at the OLT occurs $T_{eqd}$ seconds after the start of the downstream PHY frame. + +**$n_{1270}$** – The group velocity refractive index for 1270 nm wavelength light in the ODN. + +**$n_{1577}$** – The group velocity refractive index for 1577 nm wavelength light in the ODN. + +![Figure 13-7 – Time of day calculations. A timing diagram showing the interaction between an OLT and multiple ONUs (ONU_i, Farthest ONU_R, ONU*) for clock synchronization. The OLT transmits a sequence of frames: PSBd, PHY frame N, PSBd, PHY frame N+1, PSBd, PHY frame N+2. The diagram marks the 'Start of downstream frame N in OLT's view' and 'Start of upstream frame N in OLT's view'. The 'Upstream PHY frame offset' is indicated. For ONU_i, the 'ONU_i response time' and 'ONU_i assigned equalization delay' are shown. For the Farthest ONU_R, the 'ONU_R response time' is shown. The 'Tsend_N' value is marked on the OLT's timeline, and 'Trecv_{N,i}' and 'Tstamp_N' are marked on the ONU_i timeline. The 'Delta_i' (propagation delay) and 'Lambda_OLT' (OLT internal delay) are also indicated. The diagram is labeled G.987.3(10)_F13-7.](3bf1696c3034743b5ab07a0b5e398347_img.jpg) + +Figure 13-7 – Time of day calculations. A timing diagram showing the interaction between an OLT and multiple ONUs (ONU\_i, Farthest ONU\_R, ONU\*) for clock synchronization. The OLT transmits a sequence of frames: PSBd, PHY frame N, PSBd, PHY frame N+1, PSBd, PHY frame N+2. The diagram marks the 'Start of downstream frame N in OLT's view' and 'Start of upstream frame N in OLT's view'. The 'Upstream PHY frame offset' is indicated. For ONU\_i, the 'ONU\_i response time' and 'ONU\_i assigned equalization delay' are shown. For the Farthest ONU\_R, the 'ONU\_R response time' is shown. The 'Tsend\_N' value is marked on the OLT's timeline, and 'Trecv\_{N,i}' and 'Tstamp\_N' are marked on the ONU\_i timeline. The 'Delta\_i' (propagation delay) and 'Lambda\_OLT' (OLT internal delay) are also indicated. The diagram is labeled G.987.3(10)\_F13-7. + +**Figure 13-7 – Time of day calculations** + +### 13.2.2 ONU clock synchronization process + +The following process synchronizes the slave clock of the ONU to the master clock of the OLT: + +- 1) The OLT selects a downstream PHY frame to be used as the timing reference. This frame is identified by superframe counter $N$ and has an associated $T_{send_N}$ value. It is recommended that the selected frame be within a ten-second window of the current time. +- 2) The OLT calculates the $T_{stamp_N}$ value, which is based on the $T_{send_N}$ value of frame $N$ . This calculation is given by: + +$$T_{stamp_N} = T_{send_N} + \Delta_{OLT}$$ + +where: + +$$\Delta_{OLT} = Teqd \frac{n_{1577}}{n_{1270} + n_{1577}}$$ + +Note that the $T_{send_N}$ and $T_{stamp_N}$ values are all referenced to the optical interface to ensure that they are invariant to the implementation. The OLT is responsible for compensating for all its internal delays. + +- 3) This value pair ( $N$ , $T_{stamp_N}$ ) is stored locally at the OLT side. +- 4) The OLT sends this value pair ( $N$ , $T_{stamp_N}$ ) to one or more ONUs via OMCI. +- 5) ONU $i$ calculates the $T_{recv_{N,i}}$ value based on the $T_{stamp_N}$ and its own timing parameters. This calculation is given by: + +$$T_{recv_{N,i}} = T_{stamp_N} - \Delta_i$$ + +where: + +$$\Delta_i = (EqD_i + RspTime_i) \frac{n_{1577}}{n_{1270} + n_{1577}}$$ + +The exact value of response time for ONU $i$ must be used. Note that the $T_{stamp_N}$ and $T_{recv_N}$ values are all referenced to the ONU's optical interface to ensure that they are invariant to the implementation. The ONU is responsible for compensating for all of its internal delays. + +- 6) When ONU $i$ receives an arbitrary downstream PHY frame $K$ , it can set its ToD clock to the value $T_{\text{recv},K,i} = T_{\text{recv},N,i} + (K - N) \times 125.0 \mu\text{s}$ . Care should be taken to account for the superframe counter rolling over. The ONU is expected to complete clock synchronization within 10 s of communication of the $(N, T_{\text{stamp},N})$ value pair via OMCI. +- 7) Whenever the ONU's equalization delay is adjusted while the setting of the ToD clock is still pending, the ONU makes the commensurate adjustment in its predicted $T_{\text{recv},N,i}$ value. In this way, the ToD clock tracks any drifts in propagation delay of the PON system. + +It is assumed (and holds true for a common XG-PON system) that the OLT supports one and only one ToD clock domain. If this is the case, then the XG-PON system clock can be synchronized to the ToD clock, thus allowing the periodicity of the ToD distribution procedure to be relaxed. The case of multiple ToD clock domains per OLT is out of scope. + +### 13.2.3 Performance analysis + +This clause does not impose any new system requirements. The analysis contained herein is based on the requirements formulated elsewhere in this Recommendation. + +#### 13.2.3.1 Equalization delay accuracy + +The accuracy of equalization delay is determined by the DOW threshold (see clause 13.1.6), which in the 2.48832 Gbit/s XG-PON network is recommended to be $\pm 8$ bits, or approximately $\pm 3$ ns. This is very much smaller than the overall system timing requirement of $1 \mu\text{s}$ , so this can likely be neglected. + +#### 13.2.3.2 Fibre propagation delay + +For typical SMF-28 fibres, $n_{1270} = 1.4677$ , $n_{1577} = 1.4686$ . The estimate of the index correction factor is thus: + +$$\frac{n_{1577}}{n_{1270} + n_{1577}} = 0.500153$$ + +Note that using the approximate value of 0.5 for this constant would result in a systematic error of 170 ppm, which over a $200 \mu\text{s}$ PON is an error of 34 ns. It should be noted that different fibres may exhibit different absolute refractive indices; however, the relative dispersion between 1270 nm and 1577 nm is very well controlled. See Appendix II for the details of the error analysis. + +#### 13.2.3.3 Internal timing corrections + +Both the OLT and ONU are responsible for compensating for their internal delays from wherever the logical computations and/or event triggers occur to the optical interfaces, which are used as reference points for standardization purposes. In the PON system, the TDMA requirements imply that these internal delays are stable at least over each ranging life-cycle to the accuracy given above ( $\pm 8$ bits). The stability and predictability of PON equipment over longer time periods is not specified. However, one can expect the cycle-to-cycle variability to be contained within the bounds of $\pm 16$ bits at 2.5 Gbit/s, which corresponds to two uncontrolled serializer-deserializer delays in the downstream link. Even in this case, the resulting timing uncertainty of $\pm 6.4$ ns is very small. + +# 14 Performance monitoring, supervision, and defects + +This clause focuses on mechanisms to detect link failure and monitor the health and performance of links. It does not cover functions that may utilize the performance monitoring information, such as station management, bandwidth allocation or provisioning. + +## 14.1 Performance monitoring + +To facilitate troubleshooting, it is desirable that OLT and ONU maintain a variety of performance monitoring (PM) counters. The collected counter values may trigger actions ranging from threshold crossing alerts to alarms to protection switching, which are largely beyond the scope of this Recommendation. + +This clause identifies mandatory and optional PM parameters, and for the PM parameters collected at the OLT, it indicates whether they should be collected individually for each ONU or on an aggregate basis for all ONUs. + +Monitoring of optical parameters, for example, transmitted and received optical power, is specified in [ITU-T G.988]. + +Counters collected at the ONU are available to the OLT through OMCI. + +Table 14-1 identifies performance monitoring parameters for PHY, XGEM, PLOAM and OMCI. + +**Table 14-1 – Performance monitoring parameters** + +| Parameter | Mandatory or optional | Description | Collected by each ONU | Collected by OLT for each ONU i | Collected by OLT | +|------------------------------------------|-----------------------|----------------------------------------------------------------------------------------------|-----------------------------|----------------------------------------------------|------------------| +| PHY PM | | | | | | +| Corrected FEC bytes | M | The number of bytes that were corrected by the FEC function. | Yes, for all traffic flows. | Yes, if upstream FEC is enabled for ONU i . | N/A | +| Corrected FEC codewords | M | Count of FEC codewords that contained errors but were corrected by the FEC function. | Yes, for all traffic flows. | Yes, if upstream FEC is enabled for ONU i . | N/A | +| Uncorrectable FEC codewords | M | Count of FEC codewords that contained errors and could not be corrected by the FEC function. | Yes, for all traffic flows. | Yes, if upstream FEC is enabled for ONU i . | Yes | +| Total FEC codewords | M | Count of total received FEC codewords. | Yes, for all traffic flows. | Yes, if upstream FEC is enabled for ONU i . | Yes | +| Total received words protected by BIP-32 | M | Count of received 4-byte words that are included in BIP-32 check. | N/A | Yes | Yes | +| BIP-32 errors | M | Count of bit errors according to BIP-32 (Note 1). | N/A | Yes | Yes | +| PSBd HEC error count | O | HEC error in any of the fields of PSBd. | Yes, for all traffic flows. | N/A | N/A | +| XGTC HEC error count | O | XGTC header HEC errors received. | Yes, for all traffic flows. | Yes | N/A | + +**Table 14-1 – Performance monitoring parameters** + +| Parameter | Mandatory or optional | Description | Collected by each ONU | Collected by OLT for each ONU i | Collected by OLT | +|--------------------------------------------------------------------|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------|----------------------------------------|---------------------| +| Unknown profile | O | ONU could not transmit because the specified burst profile was not known. | Yes | N/A | N/A | +| XGEM PM | | | | | | +| Transmitted XGEM frames | M | Total number of XGEM frames transmitted. | Yes | No | Yes | +| Transmitted XGEM frames per XGEM port | O | The number of XGEM frames transmitted. | Yes, per XGEM port. | No | Yes, per XGEM port. | +| Received XGEM frames | M | Total number of XGEM frames received. | No | No | Yes | +| Received XGEM frames per XGEM port | O | The number of XGEM frames received. | Yes, per XGEM port that belongs to the ONU. | No | Yes, per XGEM port. | +| Count of the number of transmitted XGEM frames with LF bit NOT set | O | Number of transmit fragmentation operations. | Yes | No | Yes | +| XGEM frame header HEC errors | M | Number of events involving loss of XGEM channel delineation. | Yes | Yes | No | +| Count of XGTC frame words lost due to GEM frame HEC error | O | Aggregate severity measure of the loss of XGEM channel delineation events. Note that the number of lost XGEM frames is not available. | Yes | Yes | N/A | + +**Table 14-1 – Performance monitoring parameters** + +| Parameter | Mandatory or optional | Description | Collected by each ONU | Collected by OLT for each ONU i | Collected by OLT | +|--------------------------------|-----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------|----------------------------------------|------------------| +| XGEM key errors | M | XGEM frames discarded because of unknown or invalid encryption key. Examples include: no unicast or broadcast key established for specified key index, key index indicating encrypted XGEM frame on an XGEM port that is not provisioned for encryption, key index indicating upstream encryption on an XGEM port that is provisioned for downstream encryption only, or invalid key index (11). This count is included in the Rx XGEM frame count. | Yes | Yes | N/A | +| PLOAM PM | | | | | | +| SN grant count | O | Serial number grants for ONU discovery. | N/A | N/A | Yes | +| PLOAM MIC errors | O | | Yes | Yes | N/A | +| PLOAM timeouts | O | Retransmission count: missing, late or errored response. No response to key request or Request_Registration, lack of ACK, etc. | N/A | N/A | Yes | +| DG count | O | Count of dying gasp bursts received. | N/A | Yes | N/A | +| Downstream PLOAM message count | O | Count of PLOAM messages sent by OLT, received by ONU, either broadcast or directed to the specific ONU-ID. | Yes | Yes | Yes (broadcast) | +| Profile | O | | Yes | N/A | Yes | +| Assign_ONU-ID | O | | Yes | N/A | Yes | + +**Table 14-1 – Performance monitoring parameters** + +| Parameter | Mandatory or optional | Description | Collected by each ONU | Collected by OLT for each ONU i | Collected by OLT | +|------------------------------------------------------------------|-----------------------|-------------------------------------------------------------------------------------------------------------|------------------------------------------|----------------------------------------|------------------| +| Ranging_Time | M | Note that the count is mandatory as it provides a frequency estimate of the DOW threshold violation events. | Yes | Yes | Yes | +| Deactivate_ONU-ID | O | | Yes | N/A | Yes | +| Disable_Serial_Number | O | | Yes | N/A | Yes | +| Request_Registration | O | | Yes | Yes | N/A | +| Assign_Alloc-ID | O | | Yes | Yes | N/A | +| Key_Control | O | | Yes | Yes | Yes | +| Sleep_Allow | O | | Yes | Yes | Yes | +| Upstream PLOAM message count | O | Count of messages (other than Acknowledgement) sent by ONU, received by OLT. | Yes | Yes | | +| Serial_Number_ONU | O | | Yes | Yes
(Note 2) | Yes | +| Registration | O | | Yes | Yes | N/A | +| Key_Report | O | | Yes | Yes | N/A | +| Acknowledgement | O | | Yes | Yes | N/A | +| Sleep_Request | O | | Yes | Yes | N/A | +| OMCI PM | | | | | | +| OMCI baseline message count | O | | Yes, messages directed to the given ONU. | Yes | N/A | +| OMCI extended message count | O | | Yes, messages directed to the given ONU. | Yes | N/A | +| Autonomous messages | O | | No | Yes | No | +| OMCI MIC errors | O | | Yes | Yes | N/A | +| Energy conservation | | | | | | +| Time spent in each of the OLT/ONU low-power states, respectively | O | Time spent in each of the OLT/ONU low-power states, respectively. | Yes | Yes | N/A | + +**Table 14-1 – Performance monitoring parameters** + +| Parameter | Mandatory or optional | Description | Collected by each ONU | Collected by OLT for each ONU i | Collected by OLT | +|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------|-------------|-----------------------|----------------------------------------|------------------| +|

NOTE 1 – It is recognized that as an indicator of the number of bit errors, BIP-32 becomes inaccurate at error rates well below the worst case upstream PON specification. However, the OLT is expected to have the upstream FEC turned on to compensate the high observed BER. If this is the case, the FEC correction results should be used to obtain the accurate BER estimate.

NOTE 2 – The OLT assigns the ONU-ID and updates the per-ONU count only after recognizing the ONU's serial number.

| | | | | | + +## 14.2 Defects + +This clause captures the required actions that are performed in the TC layer, as opposed to those left to the discretion of an implementer. In particular, the effects of repeated defects of the same type are an implementation matter. + +### 14.2.1 Items detected at OLT + +| Type | Description | | | | | +|------|--------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------|---------| +| | | Detection conditions | Actions | Cancellation conditions | Actions | +| LOBi | Loss of burst for ONU i | Failure to delineate, for any reason, the specified number, Clob i , of consecutive scheduled bursts from ONU i when not exempt by power management state machine.
(Replaces conditions previously known as LOSi and LOFi.)
The Clob i threshold is configurable. Under normal conditions, it defaults to 4 missing consecutive bursts; however, under certain circumstances (such as power saving purposes), this threshold should be kept as a specific counter and set by the OLT to the ONU as according to actual number of tolerated missing bursts. | At the discretion of the OLT; may include waiting extra soak time; changing the allocation schedule; deactivating or disabling the offending ONU, or executing a rogue ONU diagnostic procedure.
Reporting of the LOBi condition should be qualified by any DG received. | A scheduled burst from ONU i successfully received. | | +| LOS | Loss of signal | The OLT did not receive any expected transmissions in the upstream (complete PON failure) for four consecutive frames. | At the discretion of the OLT; may require additional diagnostic to determine whether PON has been lost, and ultimately lead to protection switching event. | When the OLT receives at least one upstream transmission. | – | + +| Type | | Description | | | | +|-------|----------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------|---------| +| | | Detection conditions | Actions | Cancellation conditions | Actions | +| TIW | Transmission interference warning for ONU i | The ONU transmission drift exceeds the outer (TIW) threshold, and remains outside the threshold after three consecutive attempts to correct it with a Ranging_Time PLOAM message. | At the OLT discretion; may include deactivating or disabling the ONU, or executing a rogue ONU diagnostic procedure. | The ONU transmission drift does not exceed the lower (DOW) threshold. | | +| SUFi | Start-up failure of ONU i | The ranging of ONU i has failed. The OLT detects the ONU's serial number, but the ONU fails to complete the bring-up sequence. | Send Deactivate_ONU-ID PLOAM message. | The ONU is ranged successfully. | | +| DFi | Disable failure of ONU i . | The ONU continues to respond to the upstream allocations after an attempt to disable the ONU using its serial number (with one or more Disable_Serial_Number PLOAM messages) which may have been preceded by a failed attempt to deactivate the ONU (with one or more Deactivate_ONU PLOAM messages).
Note that the OLT can detect this condition only if it continues to provide upstream bandwidth allocations to the ONU. | Mitigating action at OLT discretion. May include rogue ONU diagnostic procedures. The offending ONU-ID and the associated Alloc-IDs may have to be blocked from re-allocation. | The offending ONU is successfully re-activated and remains positively controlled, or is prevented from transmitting upstream. | | +| LOPCi | Loss of PLOAM channel with ONU i | Generic defect indicating breakage of the PLOAM protocol: persistent MIC failure in the upstream; lack of acknowledgements or proper PLOAM responses from the ONU. Persistent means that the same irregular condition is observed consecutively at least three times. | Mitigating action at the OLT discretion; may include ONU re-authentication, ONU deactivation or disabling, or execution of rogue ONU diagnostic procedures. | | – | +| LOOCi | Loss of OMCI channel with ONU i | Recognized by the OLT's OMCI processing engine (based on the persistent MIC failure in the upstream). | Mitigating action at the OLT discretion; may include ONU re-authentication, ONU deactivation or disabling, or execution of rogue ONU diagnostic procedures. | | | + +### 14.2.2 Items detected at ONU + +| Type | | Description | | | | +|------|-------------------------------------|------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------|---------------------------------------------------------------------| +| | | Detection conditions | Actions | Cancellation conditions | Actions | +| LODS | Loss of downstream synchronization. | The ONU downstream synchronization state machine in the Hunt or Pre-Sync states. (see clause 10.1.2) | Provide necessary visual indication and user-side interface signalling. Execute appropriate transition of the ONU activation state machine. | The ONU downstream synchronization state machine in the Sync or Re-Sync states. | Execute appropriate transition of the ONU activation state machine. | + +# 15 XG-PON security + +This clause discusses threat models characteristic for the XG-PON operating environment, and specifies authentication, data integrity, and privacy protection aspects of the system. + +## 15.1 Threat model for XG-PON + +XG-PON security is intended to protect against the following threats: + +- a) Since downstream data is broadcast to all ONUs attached to the XG-PON OLT, a malicious user capable of replacing or re-programming an ONU would be capable of receiving all downstream data intended for all connected users. +- b) Since upstream data received by the optical line terminal (OLT) can originate from any ONU attached to the XG-PON optical distribution network (ODN), a malicious user capable of replacing or re-programming an ONU could forge packets so as to impersonate a different ONU (i.e., theft of service). +- c) An attacker could connect a malicious device at various points on the infrastructure (e.g., by tampering with street cabinets, spare ports, or fibre cables). Such a device could intercept and/or generate traffic. Depending on the location of such a device, it could impersonate an OLT or alternatively it could impersonate an ONU. +- d) A malicious user in any of the above scenarios could record packets transmitted on the passive optical network (PON) and replay them back onto the PON later, or conduct bit-flipping attacks. + +Passive optical networks (PONs) are deployed in a wide variety of scenarios. In some cases, the ODN, the optical splitter, or even the ONUs may be installed in a manner considered to be physically secure or tamper-proof. + +To accommodate these scenarios in an economical manner, activation of some of the XG-PON security features is optional, as indicated in the clauses below. + +## 15.2 Authentication + +The XG-PON system supports several mechanisms for authentication. The first mechanism is based on the registration ID. It is executed in the course of ONU activation and may be repeated throughout the duration of the activation cycle, i.e., until the ONU's next entry into the Initial state (O1). The registration-based authentication mechanism provides a basic level of authentication of the ONU to the OLT. It does not provide authentication of the OLT to the ONU. Support of the registration-based authentication mechanism is mandatory in all XG-PON devices. The two other authentication mechanisms provide secure mutual authentication to both OLT and ONU. One of them is based on an ONU management and control interface (OMCI) message exchange (see Annex C). The other is based on an IEEE 802.1X message exchange and provides a wide range of extensible features (see Annex D). Support for OMCI-based and IEEE 802.1X-based authentication mechanisms is + +mandatory for implementation at the component level, but optional from an equipment specification perspective. In other words, the transmission convergence (TC) layer implementation will have the capability to support both secure mutual authentication methods, but equipment constructed using these TC-layer implementations may choose not to support them. + +It is within the discretion of an operator to require support of one or both secure mutual authentication mechanisms at the equipment specification stage, and to employ any or none of the authentication methods, including the basic registration-based authentication, when the system is in service. + +Upon authentication failure, the OLT may undertake measures to restore functionality and to prevent a potential security breach, which may include repeating authentication using the same or an alternative mechanism, blocking upstream and downstream traffic, deactivating or disabling the offending ONU, or executing the rogue ONU diagnostic procedures. + +### **15.2.1 Registration ID-based authentication** + +The registration ID-based authentication mechanism can provide authentication of ONU to OLT, but not vice versa. Its support is mandatory for all XG-PON systems. To maintain full functionality, this method requires: + +- that a registration ID be assigned to a subscriber at the management level; +- that the registration ID be provisioned into the OLT and be communicated to field personnel or to the subscriber directly; +- that the ONU supports a method for entering the registration ID in the field (specification of such a method being beyond the scope of this Recommendation); +- that field personnel or the subscriber in fact enter the registration ID into the ONU. + +#### **15.2.1.1 The OLT perspective** + +The OLT must support the possibility to perform ONU authentication based on the reported registration ID (details of this procedure are operator-specific), as well as to execute the MSK and derived shared key calculation procedure based on the reported registration ID (see clause 15.3). + +The OLT requests the Registration ID from the ONU in the following situations: + +- In the course of ONU activation, by issuing a ranging grant; +- As a final handshake upon completion of a secure mutual authentication procedure, by sending a Request\_Registration message to the ONU; +- At any time throughout the ONU's activation cycle at its own discretion, by sending a Request\_Registration message to the ONU. + +If at the time of Registration ID receipt from the ONU, there is no valid secure mutual association (SMA) between the OLT and the ONU (i.e., in the course of ONU activation, or if secure mutual authentication has not been executed or has failed), the OLT: + +- must compute the master session key (MSK) and derived shared keys based on the reported Registration ID; +- may perform authentication of the ONU based on the reported Registration ID. + +It is up to the operator to specify whether registration-based authentication is performed and how the result is used. Failure of registration-based authentication shall not prevent the OLT from issuing an equalization delay to the ONU (i.e., the ONU is nevertheless allowed to enter the Operation state (O5)) or from maintaining management level communication with the ONU, but may have an effect on how the OLT further handles the ONU and, in particular, on subsequent provisioning of services. + +Registration-based authentication is not performed and the registration-based MSK and derived shared keys are not calculated, if at the time of the Registration ID report there exists a valid SMA between the OLT and the ONU. + +Once the OLT transmits a Request\_Registration message to the ONU while expecting to use the reported Registration ID for shared key derivation, it refrains from sending to that ONU other PLOAM or OMCI messages with ONU-specific MIC (see clauses 15.3.2 and 15.3.3) until after the Registration ID is received and the registration-based MSK and derived shared keys are calculated. + +Once the OLT completes calculation of the registration-based MSK and derived shared keys for a particular ONU, it immediately commits those keys as active. + +At the start of the ONU's activation cycle, the OLT discards any active registration-based MSK and derived shared keys. + +#### 15.2.1.2 The ONU perspective + +The ONU must be able to perform calculation of the MSK and derived share keys based on the Registration ID. + +The ONU computes the registration-based MSK and derived shared keys upon power up (initially, using the well-known default registration ID (see clause 11.3.4.2)), and each time the Registration ID changes. The computed values are stored for future use. As the registration-based key set may be required at any time, the ONU may benefit by storing the registration-based MSK and derived shared keys separately from the MSK and derived shared keys based on secure mutual authentication. + +ONU reports Registration ID to the OLT in the following situations: + +- In the course of ONU activation, in response to a ranging grant; +- At any time during the ONU's activation cycle, in response to a Request\_Registration message. + +The events that cause registration-based key re-computation are asynchronous to the physical layer operations, administration and maintenance (PLOAM) channel events. The ONU is expected to have the registration-based MSK and derived shared keys available at the time it reports its Registration ID to the OLT. + +If there is no valid SMA between the OLT and the ONU, the ONU commits the set of shared keys based the reported Registration ID immediately upon sending the Registration PLOAM message. + +The ONU retains the Registration ID and the stored registration-based MSK and derived shared keys between activation cycles and between power cycles. + +### 15.2.2 Secure mutual authentication options + +Two secure mutual authentication mechanisms are defined: OMCI-based authentication (Annex C), and IEEE 802.1X-based authentication (Annex D). These mechanisms authenticate the OLT to the ONU as well as the ONU to the OLT. The support of both secure mutual authentication mechanisms is optional on the system level. + +If secure mutual authentication is supported by the system and is employed by the operator, the OLT initiates the secure mutual authentication procedure using an appropriate mechanism upon completion of the ONU activation procedure before user data traffic is transmitted, and subsequently may initiate re-authentication at any time, subject to the operator's policies and discretion. + +In the course of execution of a secure mutual authentication procedure, the OLT and the ONU compute the secure master session key (MSK) and a set of secure shared keys applicable for specific management and operation tasks. + +Both the OLT and the ONU discard the MSK and derived shared keys obtained in the course of secure mutual authentication at the start of the ONU's activation cycle along with the other TC layer parameters. + +## 15.3 Key derivation + +The mathematical details of the MSK and derived shared key calculation are shared by the OLT and the ONU. + +The ONU computes the registration-based MSK and derived shared keys upon power up (initially using the well-known default registration ID (see clause 11.3.4.2)), and each time the Registration ID changes. + +The OLT computes the registration-based MSK and derived shared keys under the following conditions: + +- a) each time the ONU reports its registration ID to the OLT in response to a ranging grant in the course of ONU activation, regardless of whether or not the reported registration ID is used for authentication, and what the outcome of the registration-based authentication procedure is; +- b) each time the ONU reports its registration ID to the OLT in response to the Request\_Registration PLOAM message, but only when there is no valid mutual security association between OLT and ONU. + +Both the OLT and the ONU compute the secure MSK and derived shared keys each time a secure mutual authentication procedure using either the OMCI-based or the IEEE 802.1X-based mechanism is executed. + +### 15.3.1 Cryptographic method + +The secure key derivation procedure employs the cipher-based message authentication code (CMAC) algorithm specified in [NIST SP800-38B] with the advanced encryption standard (AES) encryption algorithm [NIST FIPS-197] as the underlying block cipher. + +The AES-CMAC function takes as its inputs: + +- block cipher key $K$ ; +- the information message $M$ ; and +- the bit length of the output $Tlen$ , + +and produces the message authentication code $T$ of length $Tlen$ as an output. The notation for invocation of the AES-CMAC function is: + +$$T = \text{AES-CMAC}(K, M, Tlen) \quad (15-1)$$ + +For the purposes of this Recommendation, the block size of the underlying block cipher and the bit length of the AES key are 128 bits. This version of the block cipher is referred to herein as AES-128. + +### 15.3.2 Master session key + +The master session key (MSK) is a 128-bit value that is shared between the OLT and the given ONU as a result of an authentication procedure and which serves as a starting point for the derivation of all of the other secret keys used in subsequent secure communications. + +For the registration-based key derivation, the MSK is obtained from the ONU registration ID: + +$$MSK = \text{AES-CMAC}((0x55)_{16}, \text{Registration\_ID}, 128) \quad (15-2)$$ + +Here $(0x55)_{16}$ denotes a default key composed of the hex pattern 0x55 repeated 16 times, and *Registration\_ID* is the 36-byte value transmitted in the Registration PLOAM message. Note that the Registration PLOAM message may carry either an ONU-specific *Registration\_ID*, or a well-known default value. + +When the key derivation is triggered by the success of secure mutual authentication, the procedure to obtain the MSK depends on the specific authentication mechanism. + +### 15.3.3 Derived shared keys + +The session key (SK) binds the MSK to the context of the security association between the OLT and ONU. The SK, which is used for subsequent key derivations, is obtained using the following formula: + +$$SK = \text{AES-CMAC} (MSK, (SN \mid \text{PON-TAG} \mid 0x53657373696f6e4b), 128) \quad (15-3)$$ + +where the information message, which is 24 bytes long, is a concatenation of three elements: the ONU serial number (SN, i.e., concatenation of Vendor\_ID and VSSN) as reported in octets 5 to 12 of the upstream Serial\_Number\_ONU PLOAM message (clause 11.3.4.1), the PON-TAG as reported in octets 26 to 33 of the downstream Profile PLOAM message (clause 11.3.3.1), and the hexadecimal representation of the ASCII string "SessionK". + +The OMCI integrity key (OMCI\_IK) is used to generate and verify the integrity of OMCI messages. The OMCI\_IK is derived from the SK by the following formula: + +$$OMCI\_IK = \text{AES-CMAC} (SK, 0x4f4d4349496e746567726974794b6579, 128) \quad (15-4)$$ + +Here the information message parameter of the AES-CMAC function is 128 bits long, and is the hexadecimal representation of the ASCII string "OMCIIntegrityKey". + +The PLOAM integrity key (PLOAM\_IK) is used to generate and verify the integrity of XGTC layer unicast PLOAM messages. The PLOAM\_IK is derived from the SK by the following formula: + +$$PLOAM\_IK = \text{AES-CMAC} (SK, 0x504c4f414d496e7465677274794b6579, 128) \quad (15-5)$$ + +Here the information message parameter of the AES-CMAC function is 128 bits long, and is the hexadecimal representation of the ASCII string "PLOAMIntegrityKey". + +For downstream broadcast PLOAM messages and for unicast PLOAM messages exchanged in the course of ONU activation prior to availability of the Registration-based MSK, the default PLOAM\_IK value is used, which is equal to $(0x55)_{16}$ , the subscript indicating the multiplicity of repetition of the specified hex pattern. + +The key encryption key (KEK) is used to encrypt/decrypt and protect/verify the integrity of the data encryption key that is carried in the PLOAM channel. The KEK is derived from the SK by the following formula: + +$$KEK = \text{AES-CMAC} (SK, 0x4b6579456e6372797074696f6e4b6579, 128) \quad (15-6)$$ + +Here the information message parameter of the AES-CMAC function is 128 bits long, and is the hexadecimal representation of the ASCII string "KeyEncryptionKey". + +## 15.4 XGEM payload encryption system + +XGEM payloads can be encrypted for transmission to provide data privacy in the presence of a potential eavesdropping threat. + +### 15.4.1 Cryptographic method + +The algorithm used for XG-PON encapsulation method (XGEM) payload encryption is the AES-128 [NIST FIPS-197] cipher, used in Counter mode (AES-CTR), as described in [NIST SP800-38A]. The AES-CTR algorithm applies a forward cipher with a secret key known only to the OLT and ONU (or ONUs – in the case of a broadcast key) to a sequence of input counter blocks to produce a sequence of output blocks that are exclusive-OR-ed with the plaintext XGEM payload. The sequence of counter blocks is initialized for each XGEM frame payload field to a value called "initial counter block" and is incremented using a standard incrementing function applied to the entire counter block (see section B.1 of [NIST SP800-38A]). To decrypt the ciphertext, for each XGEM frame, the forward cipher with the same secret key is applied to a sequence of input counter blocks initialized to the same initial counter block value. The output blocks are exclusive-OR-ed with the blocks of ciphertext XGEM payload to restore the plaintext XGEM payload. + +### 15.4.2 Secret key selection + +XGEM payload encryption may apply to any unicast transmission in the downstream and upstream directions, and to one specified multicast service stream for downstream broadcast transmission. The OLT ensures that, at all times, there is a PON-wide broadcast key pair which is used for broadcast XGEM Port-ID or Port-IDs, and that there is a unicast key pair for each ONU which is used for all XGEM Port-IDs that belong to that ONU. See clause 15.5 for the key exchange and activation mechanism that, at all times, allows to select a valid key for each supported key pair. + +The key pair to be used for XGEM payload encryption depends on the XGEM Port-ID. Given the XGEM Port-ID (unicast or broadcast), the sender selects the specific key of the appropriate key pair, according to the rules of clause 15.5, and provides an indication of the selected key in the XGEM header. + +Each XGEM frame header, as defined in clause 9.1.2, contains a 2-bit field designated as the key index, carrying an indication whether or not the particular XGEM frame payload is encrypted and if so, which of the encryption keys was used. The following code points are defined for the key index field: + +- 00 – XGEM frame payload is unencrypted; +- 01 – XGEM frame payload is encrypted using the first encryption key; +- 10 – XGEM frame payload is encrypted using the second encryption key; +- 11 – Reserved. + +### 15.4.3 Initial counter block + +The 128-bit initial counter block value for a particular XGEM frame is determined by the values of superframe counter (SFC) and intra-frame counter (IFC) associated with the given XGEM frame. + +In the downstream direction, the SFC value is contained in the PSBd field of the PHY frame in which the given downstream XGEM frame is transmitted. In the upstream direction, the SFC value is contained in the PSBd field of the PHY frame that specifies the upstream PHY burst in which the given upstream XGEM frame is transmitted. For the purpose of the initial counter block construction, the MSB of the SFC value is omitted, and the 50-bit field is used. + +To obtain the IFC value of the given XGEM frame, the following block enumeration procedure applies (see Figure 15-1). + +![Diagram illustrating the enumeration of XGEM frames within XGTC blocks to determine the Intra-Frame Counter (IFC).](4aeaa51a3999fab21171224e238cb571_img.jpg) + +The diagram shows a sequence of XGTC frames/bursts, each 16 bytes in size. The first two blocks are labeled 'XGTC frame/burst enumerated block N' and 'XGTC frame/burst enumerated block N + 1'. Below these, four XGEM frames are shown, each consisting of an 'XGEM header' and an 'XGEM payload'. Vertical dashed lines indicate the mapping of XGEM frames to XGTC blocks. The first XGEM frame (labeled IFC = N + 1) is entirely within block N + 1. The second XGEM frame (also labeled IFC = N + 1) starts in block N and ends in block N + 1. The third XGEM frame (labeled IFC = N) is entirely within block N. The fourth XGEM frame (labeled IFC = N) starts in block N - 1 and ends in block N. The text 'G.987.3(10)\_F15-1' is in the bottom right corner. + +Diagram illustrating the enumeration of XGEM frames within XGTC blocks to determine the Intra-Frame Counter (IFC). + +Figure 15-1 – Obtaining the intra-frame counter value for an XGEM frame + +In the downstream direction, the XGTC frame of the framing sublayer (see Figure 8-1) is partitioned into 16-byte blocks, and these blocks are sequentially numbered from 0 to 8464, the last block being half-size. The size of the sequence number is 14 bits. + +In the upstream direction, the XGTC burst of the framing sublayer (see Figure 8-5) is partitioned into 16-byte blocks, and these blocks are sequentially numbered from $(\lfloor \text{StartTime}/4 \rfloor)$ to $(\lfloor \text{StartTime}/4 \rfloor + X)$ , where X is the number of complete and incomplete 16-byte blocks in the XGTC burst, less 1. The size of the sequence number is 14 bits. As a reference, at 2.5G upstream, the largest StartTime is 9719. Hence, the largest number for the first block of a burst is 2429. The maximum XGTC burst size is 9720 words or 2430 blocks. Hence, the largest possible 16-byte block number in an upstream XGTC burst is 4858. + +An XGEM frame appearing within the payload of a downstream XGTC frame or upstream XGTC burst can occur in one of four phase positions with respect to the 16-byte block boundary. The IFC of an XGEM frame is the sequence number of the 16-byte block to which the first 4 bytes of the XGEM header belong. + +The 128-bit initial counter block for a particular downstream XGEM frame is a concatenation of SFC and IFC for the given frame obtained, as described above, concatenated with itself. The 128-bit initial counter block for a particular upstream XGEM frame is a concatenation of SFC and IFC for the given frame obtained, as described above, concatenated with the bit-complement of itself. + +![Diagram illustrating the construction of the 128-bit initial counter block for downstream encryption. It shows the concatenation of Superframe counter (SFC) and Intra-frame counter (IFC) to form the initial counter block, which is then used by an AES-CTR engine with a secret key to XOR with plaintext to produce ciphertext.](3750b0149a6380885998ab3ca6a8787c_img.jpg) + +The diagram illustrates the construction of the 128-bit initial counter block for downstream encryption. At the top, two boxes represent the 'Superframe counter (SFC) 51 bits' and the 'Intra-frame counter (IFC) 14 bits'. The SFC box shows a bit range from MSB to 0, with a specific value of 49 indicated. Below these, a horizontal bar shows the concatenation of SFC(49..0) and IFC(13..0) to form the 'Initial counter block 128 bits'. This block is then input to an 'AES-CTR engine' which also receives a 'Secret key 128 bits'. The output of the engine is XORed with 'Plaintext 16 bytes' to produce 'Ciphertext 16 bytes'. The diagram is labeled G.987.3(10)\_F15-2. + +Diagram illustrating the construction of the 128-bit initial counter block for downstream encryption. It shows the concatenation of Superframe counter (SFC) and Intra-frame counter (IFC) to form the initial counter block, which is then used by an AES-CTR engine with a secret key to XOR with plaintext to produce ciphertext. + +**Figure 15-2 – Initial counter block construction for downstream encryption +(for upstream, the shaded fields are taken in bit-complement)** + +NOTE – It has been shown that two SFC (49..0) values, 0b1(0)49 and 0b0(1)49, can lead to several duplicated counter blocks in the upstream and downstream directions. As these values appear at the middle of the SFC(49..0) range, the window of weaker counter blocks occurs for approximately 250 µs once in 4000 years. The potential impact can be mitigated by initializing the SFC to a small value. + +## 15.5 Data encryption key exchange and activation mechanism + +### 15.5.1 Overview + +The data encryption configuration of an ONU is provisioned over OMCI. Each ONU advertises its security capabilities, which are required to include at least AES-128. The OLT is free to select zero or any one of the ONU's advertised capabilities; the OLT's choice then becomes binding on the ONU. For each non-default XGEM port, the OLT configures the port's encryption key ring attribute (GEM port network CTP managed entity, clause 9.2.3 of [ITU-T G.988]), which specifies whether the port is provisioned for encryption, and if so, in which direction encryption applies (downstream only or both downstream and upstream), and which data encryption key type (unicast or broadcast) should be used for the encrypted traffic. The default XGEM port has no configurable key ring, and is defined for bidirectional encryption using the unicast type key. + +Provisioning a non-default XGEM port for encryption does not imply the traffic is always encrypted. The encryption status of each individual XGEM frame is determined dynamically by the sender, within the explicitly configured or pre-defined capabilities of the associated XGEM port, and is indicated in the XGEM frame header. + +Whenever the default XGEM port traffic is encrypted in the downstream direction, the ONU is expected to encrypt the default XGEM port traffic upstream. + +For each of two key types (unicast and broadcast), both the OLT and the ONU maintain an indexed array of two data encryption key entries. The broadcast keys are generated by the OLT and communicated to the ONUs via OMCI as described in clause 15.5.4. The unicast keys are generated and communicated upstream by the ONU upon the OLT's instructions using the PLOAM channel as described in clause 15.5.3. The value of the unicast key is not exposed to the OMCI. + +The type of the data encryption key used to encrypt the payload of a particular XGEM frame on transmission is implicit in the XGEM Port-ID. The Key\_Index field of the XGEM frame header indicates whether the payload is encrypted and, if so, which of the two data encryption keys of the given type is used. The specific key selected for encryption shall be valid at the XGEM frame transmission time, as determined by the respective key exchange protocol. The sender starts using the new data encryption key during the time interval when both keys of the respective type are valid. When no valid data encryption key is available (e.g., immediately after ONU reactivation), the sender transmits XGEM frames without encryption using a Key\_Index value of 0. + +### 15.5.2 Cryptographic method + +The data encryption keys are themselves transmitted between the OLT and the ONU encrypted with the AES-128 block cipher [NIST FIPS-197] which is used in Electronic Codebook mode (AES-ECB), as specified in [NIST SP800-38A]. In AES-ECB encryption, the forward AES-128 function is applied directly and independently to each block of plaintext using a secret key to produce a block of ciphertext. In AES-ECB decryption, the inverse AES-128 function is applied directly and independently to each block of ciphertext with the same secret key to restore the original block of plaintext. The notation for invocation of the AES-ECB algorithm is: + +$$C = \text{AES-ECB}(K, P);$$ + +$$P = \text{AES-ECB}^{-1}(K, C).$$ + +Here $P$ is a block of plaintext, $C$ is a block of ciphertext, and $K$ is the block cipher key. For the purposes of this Recommendation, both the block size and the key length are equal to 128 bits. + +### 15.5.3 Unicast encryption + +The OLT and the ONU maintain a number of logical state variables that are associated with the encryption and decryption functions, and this state information guides the exchange and activation of new key material. The OLT's state diagram is shown in Figure 15-4, and the ONU's diagram is shown in Figure 15-5. Both of the state machines run entirely in the Operation state (O5). When the ONU is activated or reactivated, the data encryption keys are invalidated and are reacquired via PLOAM exchange after the shared KEK is established. + +#### 15.5.3.1 Sequence of encryption key exchange and activation events + +The process of unicast data encryption key exchange and activation is performed under the control of the OLT by means of a series of PLOAM messages. The activation process events are given below: + +- The OLT begins by requesting a new unicast data encryption key from the ONU by using the Key\_Control(Generate) PLOAM message that contains the key index for the new key. A single copy of the request is sent, and if there is no response, the OLT should retry the request. +- Upon receipt of the Key\_Control(Generate) PLOAM message from the OLT, the ONU generates a new encryption key using a random number generator suitable for cryptographic + +purposes. The ONU stores the new key in its encryption control and decryption control structures (according to the specified key index). The ONU then sends the new key to the OLT using the Key\_Report(NewKey) PLOAM message. The key is encrypted in the Key\_Report(NewKey) PLOAM message with AES-ECB using KEK. + +- When the OLT receives the Key\_Report(NewKey) PLOAM message, it decrypts the new key and stores it in its logical encryption control and decryption control structures for the originating ONU, according to the specified key index. +- The OLT then sends the Key\_Control(Confirm) PLOAM message that contains the key index of the newly generated key. +- When the ONU receives the Key\_Control(Confirm) PLOAM message, it knows that the OLT now has the new key. Therefore, the ONU changes the new key state in the encryption control structure to active. The ONU responds with a Key\_Report(ExistingKey) PLOAM message indicating the "Key\_Name" of the specified key. +- If, at any time, the OLT wishes to check the ONU's key against its own (to diagnose a key mismatch situation), the OLT can issue a Key\_Control(Confirm) PLOAM message for a key\_index of an existing key. This triggers the ONU to respond with a Key\_Report(ExistingKey) PLOAM message containing the key name. + +Clauses 15.5.3.2 and 15.5.3.3 outline the ideal scenario of unimpaired key exchange. Implementers are encouraged to refer to the notes at the end of those subclauses. + +If on receipt of a Key\_Report(ExistingKey) PLOAM message, the OLT discovers a discrepancy between the reported and locally computed key hashes, it should stop using the data encryption key with the specified key index and take remediation actions at its own discretion. Such actions may include, for example, reconfirmation of the key, generation of a new key, or re-authentication of the ONU. + +Referring to the state diagrams of Figures 15-3 and 15-4, the notational conventions "oldkey" and "newkey" denote the two data encryption keys (with the corresponding key indices), of which the former is active before the key exchange is initiated, and the latter, after the key exchange is completed. + +Note that in the course of the key exchange in the view of both the OLT and the ONU, the moment the oldkey ceases to be valid for transmit differs from the moment the oldkey ceases to be valid for receive, and the moment the newkey becomes valid for transmit differs from the moment the newkey becomes valid for receive. + +For the OLT as well as for the ONU, there is a time interval when both oldkey and newkey are valid for transmit, and there is a time interval when both oldkey and newkey are valid for receive. Within the interval when both oldkey and newkey are valid for transmit, the respective sender selects a moment when it starts encrypting the outgoing XGEM frame payload with the newkey and putting the key\_index of the newkey into the outgoing XGEM frame header. Once the sender switches to using the newkey for transmit, the sender should stop using and discard the oldkey for transmit. Within the interval when both oldkey and newkey are valid for receive, the receiver accepts either key\_index to decrypts the incoming XGEM frame payload. Outside that interval, the receiver discards the XGEM frame payload that is encrypted with an invalid key. + +It is the responsibility of the OLT to ensure that the key\_index parameter of the Key\_Control PLOAM messages is set correctly. In particular, the OLT should abstain from sending Key\_Control(Confirm) PLOAM message for the key\_index that is presently invalid at the ONU and, except for the key mismatch recovery situations, from sending Key\_Control(Generate) PLOAM message for the only currently valid key\_index at the ONU. + +![Sequence diagram illustrating key validity in key exchange between OLT and ONU. The diagram shows the exchange of Key_Control, Key_Report, and Key_Ack messages. It also indicates the validity of old and new keys for transmission (Tx) and reception (Rx) at both ends. A legend at the bottom defines the key states: Valid key (solid line), Invalid key (dashed line), Tx_key (Key for transmit), and Rx_key (Key for receive).](7b7596fb5ef925025341a9aacb6f2be7_img.jpg) + +The diagram illustrates the key exchange process between an OLT and an ONU. The sequence of events is as follows: + +- Initial State:** Both OLT and ONU have **Tx\_oldkey** and **Rx\_oldkey** as valid keys (solid lines). **Tx\_newkey** and **Rx\_newkey** are invalid (dashed lines). +- OLT Key Request:** The OLT sends a **Key request** to the ONU. The OLT's **Tx\_newkey** becomes invalid (dashed line). +- ONU Key Generating:** The ONU generates a new key and sends a **Key\_Report (NewKey)** to the OLT. The ONU's **Rx\_newkey** becomes invalid (dashed line). +- OLT Key Confirm:** The OLT receives the new key and sends a **Key confirm** to the ONU. The OLT's **Tx\_newkey** becomes valid (solid line). +- ONU Key Ack:** The ONU receives the confirm and sends a **Key\_Ack** to the OLT. The ONU's **Rx\_newkey** becomes valid (solid line). +- OLT Key Confirm Waiting:** The OLT enters a waiting state, sending a **Key\_Control (Confirm)** message. The OLT's **Tx\_newkey** becomes valid (solid line). +- ONU Key Report:** The ONU sends a **Key\_Report (ExistingKey)** to the OLT. The ONU's **Rx\_newkey** becomes valid (solid line). +- Final State:** Both OLT and ONU have **Tx\_newkey** and **Rx\_newkey** as valid keys (solid lines). **Tx\_oldkey** and **Rx\_oldkey** are invalid (dashed lines). + +**Legend:** + +- Valid key (solid line) +- Invalid key (dashed line) +- Tx\_key: Key for transmit +- Rx\_key: Key for receive + +G.987.3(10)-Amd.1(12)\_F15-3 + +Sequence diagram illustrating key validity in key exchange between OLT and ONU. The diagram shows the exchange of Key\_Control, Key\_Report, and Key\_Ack messages. It also indicates the validity of old and new keys for transmission (Tx) and reception (Rx) at both ends. A legend at the bottom defines the key states: Valid key (solid line), Invalid key (dashed line), Tx\_key (Key for transmit), and Rx\_key (Key for receive). + +**Figure 15-3 – Key validity in key exchange** + +#### 15.5.3.2 OLT states and state diagram + +The five OLT states of encryption key exchange and activation are defined as follows: + +##### a) Key Inactive state (KL0) + +The ONU is registered and is in state O5. There is no active key for XGEM payload encryption. No keys are valid to receive and/or transmit between the OLT and the ONU. When the OLT decides to initiate the unicast data encryption key exchange, it moves to the Key Request state (KL1). + +##### b) Key Request state (KL1) + +The OLT initiates a new key request by sending a **Key\_Control(Generate)** PLOAM message, that instructs the ONU to generate a new key and to send it upstream. In this state, the new key is yet unknown to the OLT and, therefore, is invalid to receive and invalid to transmit. If there is an old key (i.e., an existing key), the old key remains valid to receive and valid to transmit at the OLT. Once a **Key\_Report(NewKey)** PLOAM message is received, the OLT moves to the Key Confirm state (KL2). If timer TK2 expires and no **Key\_Report(NewKey)** message is received, the OLT initiates a new key request. + +##### c) Key Confirm state (KL2) + +In this state, the new key is valid to transmit and invalid to receive at the OLT. The old key (if there is an old key) is valid to receive and valid to transmit at the OLT. The OLT selects the moment to begin encrypting XGEM payload with the new key. + +##### d) Key Confirm Waiting state (KL3) + +The OLT sends a **Key\_Control(Confirm)** PLOAM message for the specified key index. The new key becomes valid to receive and valid to transmit at the OLT. The old key (if there is an old key) remains valid to receive but becomes invalid to transmit at the OLT. Once a **Key\_Report(ExistingKey)** PLOAM is received, the OLT moves to the Key Active state (KL4). + +If timer TK3 expires and no **Key\_Report(ExistingKey)** has been received, the OLT sends a new **Key\_Control(Confirm)** PLOAM message. + +##### e) Key Active state (KL4) + +Once a Key\_Report(ExistingKey) PLOAM message is received, the old key (if there is an old key) becomes invalid to receive and invalid to transmit. The new key is the only active key for receive and transmit between the OLT and the ONU. + +If a rekey is required, the OLT moves to the Key Request state (KL1). + +If a key check is required, the OLT sends a Key\_Control(Confirm) PLOAM message, but no state transition occurs. + +To support encryption key exchange and activation, the OLT maintains three timers: + +TK1 – OLT key exchange waiting timer. Timer TK1 is used to abort an unsuccessful key exchange or key check attempt by limiting the overall time an OLT can sojourn in states KL1, KL2, and KL3. The recommended initial value of TK1 is 100 ms. + +TK2 – Key waiting timer. Timer TK2 is used to abort an unsuccessful key request attempt by limiting the overall time an OLT can sojourn in state KL1. The recommended initial value of TK2 is 10 ms. + +TK3 – Key confirmation waiting timer. Timer TK3 is used to abort an unsuccessful key confirmation request attempt by limiting the overall time an OLT can sojourn in state KL3. The recommended initial value of TK3 is 10 ms. + +Figure 15-4 shows a graphic representation of the states of the OLT. + +![Figure 15-4 – OLT key exchange state diagram](9fc0c37f0024c76bce2fb5115a7f2c50_img.jpg) + +``` +stateDiagram-v2 + [*] --> KL0: Key Inactive, No keys valid + KL0 --> KL1: Key Request, Send Key_Control (new), Set TK2 + KL1 --> KL2: Key Confirm, New key valid to Tx, Begin to Tx with new key + KL2 --> KL3: Key Confirm Waiting, Send Key_Control (confirm), New key valid to Rx, Old key invalid to Tx, Set TK3 + KL3 --> KL4: Key Active, Old key invalid to Rx + KL4 --> KL1: Begin rekey exchange + KL1 --> KL0: Timer TK2 expires + KL2 --> KL0: Timer TK1 expires + KL3 --> KL0: Timer TK3 expires +``` + +The state diagram illustrates the OLT key exchange process. It starts at the initial state (Key Inactive, No keys valid) and transitions to the Key Request state (Send Key\_Control (new), Set TK2). From there, it moves to the Key Confirm state (New key valid to Tx, Begin to Tx with new key), then to the Key Confirm Waiting state (Send Key\_Control (confirm), New key valid to Rx, Old key invalid to Tx, Set TK3), and finally to the Key Active state (Old key invalid to Rx). A 'Begin rekey exchange' transition returns the OLT to the Key Request state. Timer expirations (TK1, TK2, TK3) lead back to the initial state from the Key Request, Key Confirm, and Key Confirm Waiting states respectively. + +G.987.3(10)-Amd.1(12)\_F15-4 + +Figure 15-4 – OLT key exchange state diagram + +**Figure 15-4 – OLT key exchange state diagram** + +NOTE – For best practice clarifications of the OLT and ONU unicast data encryption key exchange state machines, please refer to [b-ITU-T G Suppl.81], Practical aspects of PON security (see clause 6.2). + +#### 15.5.3.3 ONU states and state diagram + +The five ONU states of encryption key exchange and activation are defined as follows: + +##### a) Key Inactive state (KN0) + +The ONU is registered and is in state O5. There are no active keys for XGEM payload encryption between the OLT and the ONU. When a Key\_Control(Generate) PLOAM message for a new key is received, the ONU moves to the Key Generating state (KN1). + +##### b) Key Generating state (KN1) + +The ONU generates a new key. If there is an old key, the old key is valid to receive and valid to transmit at the ONU. The new key is invalid to receive and invalid to transmit at the ONU. + +##### c) Key Ack Waiting state (KN2) + +The ONU sends a Key\_Report(NewKey) PLOAM message to inform the OLT of the new key. The new key is encrypted for PLOAM transmission with AES-ECB using KEK. The new key becomes valid to receive and remains invalid to transmit at the ONU. Once a Key\_Control(Confirm) PLOAM message is received, the ONU moves to the Key Ack state (KN3). + +If timer TK5 expires and no Key\_Control(Confirm) message is received, the ONU resends the Key\_Report(NewKey) PLOAM message with the new key. If the ONU receives a new Key\_Control(Generate) PLOAM message, it also resends the Key\_Report(NewKey) PLOAM message. In this case it is at ONU's discretion to use a previously generated key, or to generate yet another new key. + +##### d) Key Ack state (KN3) + +In this state, the new key is valid to receive and becomes valid to transmit at the ONU. The old key (if there is an old key) remains valid to transmit but becomes invalid to receive at the ONU. The ONU begins to encrypt XGEM payload with the new key. The ONU acknowledges the OLT by sending a Key\_Report(ExistingKey) PLOAM message with the Key\_Name of the newly generated key. Once the Key\_Report(ExistingKey) PLOAM message is sent, the ONU moves to the Key Active state (KN4). + +##### e) Key Active state (KN4) + +In this state, the new key is valid to receive and valid to transmit at the ONU. The old key (if there is an old key) becomes invalid to receive and invalid to transmit at the ONU. + +Once a Key\_Control(Generate) PLOAM message is received for the presently inactive key\_index, the ONU moves to the Key Generating state (KN1) with the active key being referenced to as old key. + +If at any time a Key\_Control(Confirm) PLOAM message is received for the existing key, the ONU sends a Key\_Report(ExistingKey) PLOAM message, but no state transition occurs. + +To support encryption key exchange and activation, the ONU maintains two timers: + +TK4 – ONU key exchange waiting timer. Timer TK4 is used to abort an unsuccessful key exchange or key check attempt by limiting the overall time an ONU can sojourn in the set of states KN1, KN2, and KN3. The recommended initial value of TK4 is 100 ms. + +TK5 – Key Ack waiting timer. Timer TK5 is used to limit the overall time an ONU can sojourn in state KN2. The recommended initial value of TK5 is 20 ms. + +Figure 15-5 shows a graphic representation of the states of the ONU. + +![ONU key exchange state diagram showing five states: KN0 (Key Inactive), KN1 (Key Generating), KN2 (Key Ack Waiting), KN3 (Key Ack), and KN4 (Key Active). Transitions are triggered by events like 'Receive Key_Control (new)', 'Timer TK4 expires', 'Send Key_Report (new)', 'Receive Key_Control (confirm)', 'Timer TK5 expires', and 'Receive Key_Control (new)'.](2dd10dd89365981b6b6154de6390a602_img.jpg) + +``` + +stateDiagram-v2 + [*] --> KN0: KN0: Key Inactive, No keys valid + KN0 --> KN1: Receive Key_Control (new), Set TK4 + KN1 --> KN2: KN1: Key Generating, Create new key + KN2 --> KN3: Receive Key_Control (confirm) + KN2 --> KN0: Timer TK5 expires + KN2 --> KN1: Receive Key_Control (new) + KN3 --> KN4: KN3: Key Ack, New key valid to Tx, Old key invalid to Rx, Begin to Tx with new key, Send Key_Report (confirm) + KN4 --> KN0: Timer TK4 expires + KN4 --> KN1: Receive Key_Control (new) + +``` + +G.987.3(10)-Amd.1(12)\_F15-5 + +ONU key exchange state diagram showing five states: KN0 (Key Inactive), KN1 (Key Generating), KN2 (Key Ack Waiting), KN3 (Key Ack), and KN4 (Key Active). Transitions are triggered by events like 'Receive Key\_Control (new)', 'Timer TK4 expires', 'Send Key\_Report (new)', 'Receive Key\_Control (confirm)', 'Timer TK5 expires', and 'Receive Key\_Control (new)'. + +**Figure 15-5 – ONU key exchange state diagram** + +NOTE – For best practice clarifications of the OLT and ONU unicast data encryption key exchange state machines, please refer to [b-ITU-T G Suppl.81], Practical aspects of PON security (see clause 6.2). + +### 15.5.4 Downstream multicast encryption + +The key exchange process is initiated by the OLT. The OLT selects the key index to be changed. The OLT takes this key index out of use, to avoid key mismatch during the process of re-keying. The OLT generates each broadcast key using a random number generator suitable for cryptographic purposes. + +Via OMCI, the OLT then writes the key to the broadcast key table attribute (see clause 9.13.11 of [ITU-T G.988]) in the MIB of each ONU that is provisioned to receive multicast traffic. The broadcast encryption key is encrypted with the AES-ECB algorithm using the KEK. + +The OMCI is an acknowledged channel, so the OLT can confirm that the ONU has indeed modified the key attribute in question. Once the OLT has confirmed that all relevant ONUs have the new broadcast key, the OLT can put the key index back into service. + +## 15.6 Integrity protection and data origin verification for PLOAM + +For the PLOAM messaging channel, sender identity verification and protection against forgery is achieved with the use of the 8-byte message integrity check (MIC) field of the PLOAM message format. + +### 15.6.1 Cryptographic method + +The MIC field of the PLOAM message format is constructed using the cipher-based message authentication code (CMAC) algorithm specified in [NIST SP800-38B] with the 128-bit Advanced encryption standard (AES-128) encryption algorithm [NIST FIPS-197] as the underlying block cipher. + +The parameters and the notation for invocation of the AES-CMAC function are described in clause 15.3.1. + +### 15.6.2 MIC calculation + +Given the 40 bytes of the PLOAM message content and the PLOAM integrity key PLOAM\_IK, the sender and receiver can calculate the MIC field as follows: + +$$PLOAM-MIC = \text{AES-CMAC}(PLOAM\_IK, C_{dir} | PLOAM\_CONTENT, 64) \quad (15-7)$$ + +Where $C_{dir}$ is the direction code: $C_{dir} = 0x01$ for downstream and $C_{dir} = 0x02$ for upstream, and $PLOAM\_CONTENT$ denotes octets 1 to 40 of the PLOAM message. + +![Diagram of PLOAM integrity protection showing the calculation of the MIC field. The PLOAM message structure includes Direction code, ONU-ID, Message type ID, SeqNo, Message Content, and MIC. The MIC is calculated by the AES-CMAC-64 engine using the PLOAM_IK (16 bytes) and the Message (41 bytes).](e60c2d24a97a2855d98671d27ea43d0f_img.jpg) + +The diagram illustrates the PLOAM integrity protection process. On the left, the PLOAM message structure is shown as a table with fields: Direction code, ONU-ID, Message type ID, SeqNo, Message Content, and MIC. The first four fields (Direction code to SeqNo) are grouped as 'Message' (41 bytes). The Message Content field (octets 5..40) is also part of the input. The MIC field (octets 41..48) is the output. The input to the AES-CMAC-64 engine is the concatenation of the Direction code, ONU-ID, Message type ID, SeqNo, and Message Content (41 bytes). The engine also takes the PLOAM\_IK (16 bytes) as input and produces an 8-byte output, which is stored in the MIC field. + +| PLOAM message | | +|---------------|-----------------| +| 1..2 | ONU-ID | +| 3 | Message type ID | +| 4 | SeqNo | +| 5..40 | Message Content | +| 41..48 | MIC | + +Diagram of PLOAM integrity protection showing the calculation of the MIC field. The PLOAM message structure includes Direction code, ONU-ID, Message type ID, SeqNo, Message Content, and MIC. The MIC is calculated by the AES-CMAC-64 engine using the PLOAM\_IK (16 bytes) and the Message (41 bytes). + +Figure 15-6 – PLOAM integrity protection + +## 15.7 Integrity protection and data origin verification for OMCI + +For the OMCC channel, the sender identity verification and protection against forgery is achieved with the use of the 4-byte message integrity check (MIC) field of the OMCI message format. + +### 15.7.1 Cryptographic method + +The MIC field of the OMCI message format is constructed using the cipher-based message authentication code (CMAC) algorithm specified in [NIST SP800-38B] with the 128-bit advanced encryption standard (AES-128) encryption algorithm [NIST FIPS-197] as the underlying block cipher. + +The parameters and the notation for invocation of the AES-CMAC function are described in clause 15.3.1. + +![Diagram of OMCI integrity protection showing the calculation of the MIC field. The OMCI message structure includes Direction code, Transaction ID, Message type, Device ID, ME ID, Message contents, and MIC. The MIC is calculated by the AES-CMAC-32 engine using the OMCI_IK (16 bytes) and the Message (N-3 bytes).](404924fde6a708196214ae2da3819428_img.jpg) + +The diagram illustrates the OMCI integrity protection process. On the left, the OMCI message structure is shown as a table with fields: Direction code, Transaction ID, Message type, Device ID, ME ID, Message contents, and MIC. The first five fields (Direction code to ME ID) are grouped as 'Message' (N-3 bytes). The Message contents field (octets 9..(N-4)) is also part of the input. The MIC field (octets (N-3)..N) is the output. The input to the AES-CMAC-32 engine is the concatenation of the Direction code, Transaction ID, Message type, Device ID, ME ID, and Message contents (N-3 bytes). The engine also takes the OMCI\_IK (16 bytes) as input and produces a 4-byte output, which is stored in the MIC field. + +| OMCI message | | +|--------------|---------------------------------------------------------------------------------------------------------------------------| +| 1..2 | Transaction ID | +| 3 | Message type | +| 4 | Device ID | +| 5..8 | ME ID | +| 9..(N-4) | Message contents (including contents length for the extended format and first four bytes of trailer for the basic format) | +| (N-3)..N | MIC | + +Diagram of OMCI integrity protection showing the calculation of the MIC field. The OMCI message structure includes Direction code, Transaction ID, Message type, Device ID, ME ID, Message contents, and MIC. The MIC is calculated by the AES-CMAC-32 engine using the OMCI\_IK (16 bytes) and the Message (N-3 bytes). + +Figure 15-7 – OMCI integrity protection + +### 15.7.2 MIC calculation + +Given the content of the OMCI message and the OMCI integrity key OMCI\_IK, the sender and receiver can calculate the MIC field as follows: + +$$OMCI\_MIC = \text{AES-CMAC}(OMCI\_IK, (C_{\text{dir}} \mid OMCI\_CONTENT), 32) \quad (15-8)$$ + +Where $C_{\text{dir}}$ is the direction code: $C_{\text{dir}} = 0x01$ for downstream and $C_{\text{dir}} = 0x02$ for upstream, and *OMCI\_CONTENT* refers to the OMCI message except the last 4 bytes. + +## 15.8 Integrity and data origin verification key switching + +### 15.8.1 Use of the default key + +At the start of ONU activation, the PLOAM integrity key for the given ONU is set to the default value of $(0x55)_{16}$ , which is used for PLOAM message exchange while no MSK is available. Once the ONU communicates its registration ID to the OLT, the basic MSK is established and all the derivative shared keys are obtained. The OMCI integrity key does not require an explicit default, as no OMCI exchange takes place prior to MSK establishment and no broadcast OMCC channel is supported. + +The broadcast PLOAM messages, the Serial\_Number\_ONU (upstream) PLOAM message, the Deactivate\_ONU-ID (downstream) PLOAM message, as well as the Request\_Registration (downstream) and Registration (upstream) PLOAM messages are always protected by a MIC that is generated with the default PLOAM integrity key. The specified messages, therefore, can be successfully transmitted even if the OLT and ONU have not established or no longer agree on the dynamically derived keys. + +### 15.8.2 Key switching for OMCI-based secure mutual authentication + +The following description refers to the Enhanced security control attributes and procedures specified in clause 9.13.11 of [ITU-T G.988]. + +The authentication is implemented as a three-step symmetric-key-based challenge-response procedure in the OMCI channel followed by a PLOAM handshake in the form of Registration ID exchange. + +The OLT initiates the OMCI-based authentication at its discretion by writing the OLT random challenge table attribute. From this point to the completion of the authentication procedure, the OLT refrains from sending to the ONU any OMCI messages unrelated to authentication. + +The ONU generates a random challenge of its own, computes the response to the OLT challenge, and initiates the secure MSK and derived shared key calculation procedure. Once computed, the secure keys are stored for future use. + +![Sequence diagram of OMCI-based secure mutual authentication procedure between OLT and ONU. The diagram shows message exchanges over OMCI, PLOAM, and KEY channels. The OLT initiates the process by setting crypto capabilities and challenge status. The ONU responds with its own challenge table and authentication results. The OLT then verifies these and sets its own authentication result table and status. The ONU verifies the OLT's status and sends an AVC message. The OLT then gets the master session key name and responds. Finally, the OLT sends a PLOAM Request_Registration and the ONU responds with PLOAM Registration. A legend indicates that white boxes represent old keys and grey boxes represent new keys. The diagram is labeled G.987.3(10)-Amd.1(12)_F15-8.](3481cde1adf61b0452dd6489dada6d6a_img.jpg) + +The diagram illustrates the OMCI-based secure mutual authentication procedure between an Optical Line Terminal (OLT) and an Optical Network Unit (ONU). The sequence of messages is as follows: + +- The OLT sends a **Set\*** message containing [OLT crypto capabilities, OLT random challenge table] to the ONU. +- The OLT sends a **Set** message [OLT challenge status = true] to the ONU. +- The ONU responds with an **AVC** message [ONU random challenge table complete] to the OLT. +- The ONU sends another **AVC** message [ONU authentication result table complete] to the OLT. +- The OLT sends a **Get** message [ONU selected crypto capabilities, ONU random challenge table, ONU authentication result table] to the ONU. +- The ONU responds with **Get\_response []** to the OLT. +- The OLT sends a **Set\*** message [OLT authentication result table] to the ONU. +- The OLT sends a **Set** message [OLT result status = true] to the ONU. +- The ONU sends an **AVC** message [ONU authentication status] to the OLT. +- The OLT sends a **Get** message [Master session key name] to the ONU. +- The ONU responds with **Get\_response []** to the OLT. +- The OLT sends a **PLOAM: Request\_Registration** message to the ONU. +- The ONU responds with **PLOAM: Registration** to the OLT. + +Legend: Old key New key + +G.987.3(10)-Amd.1(12)\_F15-8 + +Sequence diagram of OMCI-based secure mutual authentication procedure between OLT and ONU. The diagram shows message exchanges over OMCI, PLOAM, and KEY channels. The OLT initiates the process by setting crypto capabilities and challenge status. The ONU responds with its own challenge table and authentication results. The OLT then verifies these and sets its own authentication result table and status. The ONU verifies the OLT's status and sends an AVC message. The OLT then gets the master session key name and responds. Finally, the OLT sends a PLOAM Request\_Registration and the ONU responds with PLOAM Registration. A legend indicates that white boxes represent old keys and grey boxes represent new keys. The diagram is labeled G.987.3(10)-Amd.1(12)\_F15-8. + +NOTE – Set\* indicates multiple set operations as needed to fill the table + +**Figure 15-8 – OMCI-based secure mutual authentication procedure. Unless explicitly specified otherwise, the messages are exchanged over the OMCI channel** + +Upon receipt of the ONU's response to optical line terminal (OLT) random challenge along with the ONU random challenge table, the OLT unilaterally verifies the ONU's authentication status. If the unidirectional ONU-to-OLT authentication fails, further execution of the authentication procedure is aborted. If the unidirectional ONU-to-OLT authentication succeeds, the OLT calculates the MSK and the derivative shared keys, storing them for future use. Once the key calculation is completed, the OLT proceeds with execution of the authentication procedure by writing the OLT authentication result table and OLT result status to the ONU. + +Upon receipt of the OLT's response, the ONU verifies the OLT's authentication status and fills in the ONU authentication state attribute. The ONU uses the next available default Alloc-ID grant opportunity to transmit an attribute value change (AVC) on the ONU authentication state attribute. If the unidirectional OLT-to-ONU authentication has failed, a message integrity check (MIC) on the AVC message is generated using the previously active OMCI\_IK. If the unidirectional OLT-to-ONU authentication has succeeded (and thus the mutual authentication has succeeded as well), the MIC field on the AVC message is generated with the new OMCI\_IK. The new OMCI\_IK is committed active at the ONU. + +When the OLT receives the AVC on the ONU authentication state from the ONU, it checks whether the MIC field has been generated using the old OMCI\_IK or the new OMCI\_IK. If the old OMCI\_IK was used by the ONU, the OLT discards the previously calculated key material. If the new OMCI\_IK was used by the ONU, the OLT commits the new OMCI\_IK as active. The OLT then initiates a PLOAM handshake by generating a downstream Request\_Registration PLOAM message to the ONU. The purpose of the handshake is to delineate the activation of the secure shared keys in case of authentication success, or to obtain the registration-based MSK and derived shared keys in case of authentication failure. The Request\_Registration PLOAM message is protected, by definition, using the default PLOAM\_IK. Upon transmission of the Request\_Registration message, the OLT commits the new PLOAM\_IK as active on transmit. + +Once the ONU receives the downstream Request\_Registration PLOAM message, it generates an upstream Registration PLOAM message, which is protected, by definition, using the default PLOAM\_IK. Upon transmission of the Registration message, the ONU commits the new PLOAM\_IK and KEK as active. + +Once the OLT receives the upstream Registration PLOAM message from the ONU, it commits the PLOAM\_IK and KEK as active on receive, thus completing the key switching procedure. + +### 15.8.3 Key switching for IEEE 802.1x-based authentication + +Once the IEEE 802.1x-based mutual authentication or re-authentication process has completed, the OLT and the authenticated ONU have a 200 ms grace interval to compute the new set of derived shared keys. Within this interval, a sender should either remain silent or continue to use the old integrity key and switch to the new one as soon as it detects the new key in the received message, or at the end of the grace interval, at the latest. While the new key is being computed, a receiver continues checking the received messages with the old key. When the new key becomes available, the receiver should start checking messages with both old and new keys and switch to using the new key only once the new key check is successful, or at the end of the grace interval, at the latest. + +### 15.8.4 MIC failure considerations + +If MIC failure is caused by random transmission errors, then it is likely a rare event that can be correlated with the observed bit-error ratio (BER) level. A persistent MIC failure, on the other hand, is likely caused by an integrity key mismatch at the transmitter and receiver and may indicate either a security threat or a malfunction of the authentication and key generation procedure. In case of persistent message integrity check failure, of which the OLT learns either directly (upstream MIC failure) or through the lack of expected management traffic flow from the ONU (downstream MIC failure), the OLT recognizes a loss of PLOAM channel (LOPCi) defect or a loss of OMCI channel (LOOCi) defect for a given ONU and has to select, at its discretion, the appropriate mitigation actions, which may include repeating authentication using the same or an alternative mechanism, blocking upstream and downstream traffic, deactivating or disabling the offending ONU, or executing a rogue ONU diagnostic procedure. + +## 15.9 XG-PON systems with reduced data encryption strength + +Clause 15.9.1 introduces the concept of effective key length. Clause 15.9.2 contains the conditional requirements that are mandatory only for XG-PON systems with specified effective key lengths less than 128 bits. For an ONU, the effective key length is provisioned using the effective key length attribute (see clause 9.13.11 of [ITU-T G.988]). + +### 15.9.1 Effective key length + +The standard key size used for AES data encryption in XG-PON is 128 bits. Per operator requirements, an XG-PON system may optionally employ a data encryption system of reduced strength by replacing a part of the key with a well-defined bit pattern. The number of randomly generated bits of the key is referred to as the effective key length. + +### 15.9.2 Data encryption key format + +In an XG-PON system with reduced data encryption strength, the effective key length $L_{\text{eff}}$ is a multiple of 8 bits, and each network element responsible for data encryption key generation replaces the $(128 - L_{\text{eff}})/8$ most significant octets of the 128-bit key with the value 0x55, as shown in Figure 15-9. + +![Diagram showing the format of a data encryption key with reduced effective length. The key is 128 bits long. It starts with 0x55, followed by an ellipsis, then another 0x55. The remaining bits are 'Random key bits'. A double-headed arrow labeled L_eff indicates the length of the random key bits, which is the total 128 bits minus the first 0x55 byte (8 bits).](3a006a7c9c9934695f0fc731344eff8a_img.jpg) + +Diagram showing the format of a data encryption key with reduced effective length. The key is 128 bits long. It starts with 0x55, followed by an ellipsis, then another 0x55. The remaining bits are 'Random key bits'. A double-headed arrow labeled L\_eff indicates the length of the random key bits, which is the total 128 bits minus the first 0x55 byte (8 bits). + +G.987.3(10)-Amd.1(12)\_F15-9 + +**Figure 15-9 – Format of a data encryption key with reduced effective length** + +In an XG-PON system with reduced data encryption strength, a network element responsible for the generation of a data encryption key should be able to report the effective key length to the element management system. + +# 16 ONU power management + +For a variety of reasons, it is desirable to reduce the power consumed by an ONU as much as possible: + +- Over time, the natural evolution of technology tends toward more efficient realizations of given functions, a tendency that is offset, at least to some extent, by increasing levels of functionality and speed. +- If there is a way for the ONU to determine that a subscriber interface is idle, it is desirable for the ONU to power down the circuitry associated with that interface, while retaining the capability to detect subscriber activity on that interface. The details vary as a function of the interface type. +- The extent of feasible power reduction depends on the acceptable effect on service. The maximum possible savings occurs when a subscriber intentionally switches off an ONU, for example, overnight or during a vacation. +- During failures of AC power, some degradation of service is generally acceptable. To conserve backup battery lifetime, it is desirable for the ONU to power down circuitry associated with all interfaces, except those considered to provide essential services. Different operators and customers may have different definitions of essential services, and may wish to prioritize the time when the interfaces are powered down. This feature, which is known as power shedding, is described in [ITU-T G.988]. + +The preceding techniques for power management are a matter of ONU design and subscriber and operator practice, and are beyond the scope of this Recommendation. + +This clause addresses three additional means of power management, which do require TC layer support. One is called Doze mode; another is referred to as Cyclic sleep mode; the third is known as Watchful sleep mode. The Watchful sleep mode combines the semantic features of the Doze and Cyclic sleep modes while reusing the states and transition of the Doze mode on the ONU side, and those of the Cyclic sleep mode on the OLT side. + +The protocol-based ONU power management modes are negotiated via OMCI, and may be combined with any of the other power reduction techniques. + +A compliant ITU-T G.987.3 implementation may either: + +- Implement the Watchful sleep mode (which is reducible to either Doze or Cyclic sleep behaviour through parameter configuration); or +- Implement Doze mode; or +- Implement Doze and Cyclic sleep modes. + +The specific power management capabilities are subject to operators' system requirements, and for each ONU are negotiated over OMCI upon ONU activation. + +## 16.1 Power management configuration and signalling + +The OLT uses OMCI to discover the ONU's power management capabilities and to configure its power management attributes and modes. To control the power management behaviour of a given ONU, the ONU and the OLT maintain a pair of power management state machines. The ONU state machine and the corresponding OLT state machine operate in partial state alignment. The primary signalling mechanism used to coordinate the ONU and OLT state machines is based on the PLOAM messages. The output PLOAM messages are generated and queued for transmission at the time of state transitions. The states of both ONU and OLT state machines can be classified into two mutually exclusive subsets: the full power states and the power saving states. Only the state transitions between the full power and power saving state subsets generate an output PLOAM message. If the sojourn in the target state of a transition is controlled by a timer, the timer is not started until the actual transmission of the message. As a secondary signalling mechanism used to speed up or wake up a sleeping ONU, the forced wake-up indication bit is carried within a BWmap allocation structure. + +## 16.2 Power management parameter definitions + +Table 16-1 defines the essential intervals, timers and counters. Parameters known to both ONU and OLT are exchanged via OMCI [ITU-T G.988]. Parameters local to the ONU or the OLT are defined only for use in the description below. + +**Table 16-1 – Power management parameters** + +| Parameter | Description | Defined by | Known to | +|------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------|----------| +| Ilowpower | Ilowpower is the maximum time the ONU spends in a LowPower state (i.e., Asleep, Listen, or Watch state), as a count of 125 microsecond frames. Local wake-up indications (LWIs) or remote events, if detected, may truncate the ONU's sojourn in these states. | OLT | ONU, OLT | +| Tlowpower | Local timer at ONU. Upon entry to a LowPower state (i.e., Asleep, Listen, or Watch state), the ONU initializes Tlowpower to a value equal to or less than Ilowpower. Secondary internal timers may be required to guarantee that the ONU will be fully operational when it enters an Aware state after an interval not to exceed Ilowpower. | ONU | ONU | +| Iaware | Iaware is the minimum time the ONU spends in an Aware state (i.e., SleepAware, DozeAware, or WatchAware) before transitioning to a LowPower state, as a count of 125 microsecond frames. During the Iaware interval, local or remote events may independently cause the ONU to enter the ActiveHeld state rather than returning to a LowPower state. | OLT | ONU, OLT | +| Taware | Local timer at ONU, initialized to a value equal to or greater than Iaware once downstream synchronization is obtained upon entry to an Aware state (i.e., SleepAware, DozeAware, or WatchAware). Taware controls the dwell time in an Aware state before the ONU re-enters the corresponding LowPower state. | ONU | ONU | +| Itransinit | The worst-case transceiver initialization time: the time required for the ONU to gain full functionality when leaving a LowPower state, measured in units of 125 µs PHY frames, and known by design. The value of zero indicates that the ONU in a low power mode can respond to a bandwidth grant without delay. | ONU | ONU, OLT | + +**Table 16-1 – Power management parameters** + +| Parameter | Description | Defined by | Known to | +|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------|----------| +| Itxinit | Transmitter initialization time: the time required for the ONU to gain full functionality when turning on the transmitter while the receiver has remained on, measured in units of 125 µs PHY frames. The value of zero indicates that the ONU in a low power mode can respond to a bandwidth grant without delay. | ONU | ONU, OLT | +| Irxoff | Irxoff is the maximum time the OLT can afford to wait from the moment it decides to wake up an ONU in one of the low power modes until the ONU is fully operational, specified as a count of 125 µs PHY frames. The ONU timer Trxoff and the OLT timer Talerted are initialized based on Irxoff. | OLT | ONU, OLT | +| Trxoff | Local timer at ONU. The ONU uses this timer in the Watch state of the Watchful sleep mode while checking the downstream signal for the remote wakeup indications to ensure that the time between two consecutive checks does not exceed the provisioned Irxoff interval. | ONU | ONU | +| Talerted | Local timer to bound the time that the OLT state machine remains in an alerted state before entering the AwakeForced state.

Talerted should be initialized to at least Irxoff + Itransinit + round-trip delay + tolerances for Rx synchronization, bandwidth grant irregularities, and processing time. | OLT | OLT | +| Ter i | Local handshake timer at the OLT that defines the latest instant at which an upstream burst is expected from ONU i when it is in one of the low power modes. The OLT reinitializes and starts this timer when the OLT's state machine for the given ONU transitions into the LowPowerSleep or LowPowerDoze/Watch state and each time an upstream burst is received from the ONU while in that state. If Ter i expires, the OLT declares a handshake violation and attempts to force the ONU awake.

To determine the initial value of Ter i , the OLT is responsible to consider the provisioned Ilowpower interval and any possible effects of transceiver initialization, synchronization, and irregularities in the bandwidth grant cycle. | OLT | OLT | +| Ihold | Minimum sojourn in the ActiveHeld state. | OLT | ONU, OLT | +| Thold | Local timer at the ONU that is initialized to Ihold upon transmission of SR(Awake) after entry into ActiveHeld state and that enforces the minimum sojourn in the ActiveHeld state. | ONU | ONU | + +## 16.3 Power management state machine specifications + +The power management behaviour of a given ONU is controlled by a pair of state machines residing at the OLT and the ONU. While the state nomenclature of the OLT machine is similar to that of the ONU machine, the two state machines operate in just partial state alignment. The lock-step state tracking is not an objective of the protocol. + +### 16.3.1 ONU state machine + +The ONU power management states along with their corresponding semantic description are listed in Table 16-2. The set of input events is represented in Table 16-3. The state transition diagram is illustrated in Figure 16-1. The normative specification of the state transitions and outputs are given in Table 16-4. + +**Table 16-2 – ONU power management states** + +| State | Semantics | +|---------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ActiveHeld | The ONU is fully responsive, forwarding downstream traffic and responding to all bandwidth allocations. Power management state transitions do not occur. The minimum sojourn in this state is enforced by the Thold timer. Upon entry to this state, the ONU sends a Sleep_Request (Awake) PLOAM message. On the state diagrams, this is abbreviated as SR(Awake). | +| ActiveFree | The ONU is fully responsive, forwarding downstream traffic and responding to all bandwidth allocations. Power management state transition requests are a local decision. | +| Asleep | The ONU shuts down both its receiver and transmitter, retaining the ability to wake up on local stimulus. This state persists for a specified duration Ilowpower, if not truncated by the arrival of a local stimulus LWI. Before exiting this state, the ONU ensures that it is fully powered up, synchronized, and capable of responding to both upstream and downstream traffic and control. | +| Listen | The ONU receiver is on; the transmitter is off. The ONU listens to the downstream signal and forwards downstream traffic, while retaining the ability to reactivate the transmitter on local or remote stimulus. This state persists for a specified duration Ilowpower, if not truncated by the arrival of a local stimulus LWI or receipt of SA(OFF) or FWI from the OLT. Before exiting this state, the ONU ensures that it is fully powered up and capable of responding to both upstream and downstream traffic and control. | +| Watch | The ONU transmitter is off. The ONU periodically turns on the receiver for a brief time to check the downstream signal for remote wakeup indications. When the downstream signal is checked, the ONU does not respond to bandwidth allocations and does not forward downstream traffic. This state persists for a specified duration Ilowpower, if not truncated by the arrival of a local stimulus LWI or receipt of SA(OFF) or FWI from the OLT. Before exiting this state, the ONU ensures that it is fully powered up and capable of responding to both upstream and downstream traffic and control. | +| DozeAware
SleepAware
WatchAware | Both ONU receiver and transmitter remain on. This state persists for a specified duration Iaware, if not truncated by the arrival of a local stimulus LWI or receipt of SA(OFF) or FWI from the OLT. The ONU forwards downstream traffic and responds to all bandwidth allocations. It is the responsibility of the OLT to transmit bandwidth allocations containing the PLOAMu flag with frequency sufficient to ensure that an aware ONU sees at least one. | + +**Table 16-3 – ONU state machine inputs** + +| Input categories | Input | Semantics | +|----------------------|----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------| +| PLOAM events | Sleep_Allow(ON) | The OLT grants permission to the ONU to exercise any negotiated power management mode, and leaves the mode selection to the ONU's discretion. | +| | Sleep_Allow(OFF) | The OLT withholds consent to exercise a power management mode. | +| Bit-indication event | Forced wake-up indication (FWI) | Transmitting FWI as a flag of an allocation structure, the OLT requires immediate ONU wake-up and its transition to a full power state. | +| Timer events | Thold expiration | The event applies in the ActiveHeld state, controlling the minimum sojourn in that state. | +| | Taware expiration | The event applies in an Aware state (i.e., SleepAware, DozeAware, or WatchAware), controlling the sojourn in that state. | +| | Tlowpower expiration | The event applies in a LowPower state (i.e., Asleep, Listen, or Watch), controlling the sojourn in that state. | +| Local events | Local sleep indication (LSI) | The ONU has no local reason to remain at full power and is willing to exercise the cyclic sleep power management mode. | +| | Local doze indication (LDI) | The ONU has no local reason to remain at full power and is willing to exercise the doze power management mode. | +| | Local low power indication (LPI) | The ONU has no local reason to remain at full power and is willing to exercise the Watchful sleep power management mode. | +| | Local wake-up indication (LWI) | A local stimulus prevents the ONU from exercising any power management mode. | + +NOTE – The LSI, LDI, LPI, and LWI events are conceptually derived from the ONU's binary stimulus status level (Full power/Power save) along with the discretionary mode selection (CyclicSleep/Doze/Watch) and correspond to the events of the level change or, in case of ActiveFree state, to the sampled value at the time of the transition. The specific criteria for the local stimulus definition remain out of scope of this Recommendation. The recognition of the LSI/LDI/LPI events by the ONU is restricted by the power management mode/modes negotiated via OMCI. + +![ONU state transition diagram showing six states: (1) Active Held (initial state), (2) Active Free, (3) Sleep Aware, (4) Asleep, (5) Doze/watch Aware, and (6) Listen/Watch. Transitions are triggered by events like SA(OFF), FWI, LWI, LSI, LDI, LPI, and timers like Thold, Taware, and Tlowpower. Output actions include /SR (Sleep), /SR (Doze), /SR (WSleep), and /SR (Awake).](301f4a188198a15b1415d54545b07e0d_img.jpg) + +``` + +stateDiagram-v2 + [*] --> (1) Active Held + (1) --> (2) Active Free : Thold expires and SA(ON) + (2) --> (1) : SA(OFF) or FWI + (2) --> (3) Sleep Aware : LSI /SR (Sleep) + (2) --> (5) Doze/watch Aware : LDI /SR (Doze) + (2) --> (5) : LPI /SR (WSleep) + (3) --> (1) : SA(OFF) or FWI or LWI /SR (Awake) + (3) --> (4) Asleep : Taware expires + (4) --> (3) : Tlowpower expires + (4) --> (1) : LWI /SR (Awake) + (5) --> (1) : SA(OFF) or FWI or LWI /SR (Awake) + (5) --> (6) Listen/Watch : Taware expires + (6) --> (1) : SA(OFF) or FWI or LWI /SR (Awake) + +``` + +ONU state transition diagram showing six states: (1) Active Held (initial state), (2) Active Free, (3) Sleep Aware, (4) Asleep, (5) Doze/watch Aware, and (6) Listen/Watch. Transitions are triggered by events like SA(OFF), FWI, LWI, LSI, LDI, LPI, and timers like Thold, Taware, and Tlowpower. Output actions include /SR (Sleep), /SR (Doze), /SR (WSleep), and /SR (Awake). + +G.987.3(14)\_F16-1 + +Figure 16-1 – ONU state transition diagram (initial state circled) + +Notes: + +- (1) In this state diagram graph, vertices corresponding to states (1) and (2) can be qualified as tense and form a tense subgraph, whereas vertices corresponding to states (3), (4), (5) and (6) can be qualified as "relaxed" and form a relaxed subgraph. As a rule, an output PLOAM message is generated only on a state transition that crosses the subgraph boundary. +- (2) The use of the right-hand-side branch of the state machine depends on the power mode negotiations between the OLT and the ONU. If the Doze or Doze & Cyclic Sleep modes are selected, the LDI condition applies, and the states are named (5) DozeAware and (6) Listen. If the Watchful sleep mode is selected, the LPI condition applies, and the states are named (5) WatchAware and (6) Watch. However, all the transitions remain exactly the same, which is the reason to combine them graphically. + +Table 16-4 – ONU state transition and output table + +| Inputs | ONU power management states | | | | | | +|----------|--------------------------------------------|-------------------|---------------------|---------------------|---------------------------------|-------------------------| +| | (1)
ActiveHeld | (2)
ActiveFree | (3)
SleepAware | (4)
Asleep | (5)
DozeAware/
WatchAware | (6)
Listen/
Watch | +| FWI | * | → (1) | → (1)
/SR(Awake) | | → (1)
/SR(Awake) | → (1)
/SR(Awake) | +| SA (OFF) | * | → (1) | → (1)
/SR(Awake) | | → (1)
/SR(Awake) | → (1)
/SR(Awake) | +| SA (ON) | → (2)
If Thold has
expired
(Note) | * | * | | * | * | +| LWI | * | * | → (1)
/SR(Awake) | → (1)
/SR(Awake) | → (1)
/SR(Awake) | → (1)
/SR(Awake) | + +**Table 16-4 – ONU state transition and output table** + +| Inputs | ONU power management states | | | | | | +|-------------------------|------------------------------------------------------|----------------------|-------------------|---------------|---------------------------------|-------------------------| +| | (1)
ActiveHeld | (2)
ActiveFree | (3)
SleepAware | (4)
Asleep | (5)
DozeAware/
WatchAware | (6)
Listen/
Watch | +| LSI | | → (3)
/SR(Sleep) | * | * | | | +| LDI | | → (5)
/SR(Doze) | | | * | * | +| LPI | | → (5)
/SR(WSleep) | | | * | * | +| Tlowpower
expiration | | | | → (3) | | → (5) | +| Taware
expiration | | | → (4) | | → (6) | | +| Thold
expiration | → (2)
If SA(ON)
has been
received
(Note) | | | | | | + +\* Indicates a self-transition. + +■ A shaded cell means that the input is not applicable in the given state. + +NOTE – An ONU remains in the ActiveHeld state for at least Ihold upon entry into that state regardless of the SA message parameter value indicated by the OLT. The minimum sojourn in the ActiveHeld state is controlled by timer Thold that is initiated to Ihold upon ONU's entry into the ActiveHeld state. When Thold expires, the ONU executes a transition into to the ActiveFree state if the latched value of SA message parameter is ON or as soon as SA (ON) message is received. + +### 16.3.2 OLT state machine + +The OLT power management states along with their corresponding semantic description are listed in Table 16-5. The set of input events is represented in Table 16-6. The state transition diagram is illustrated in Figure 16-2. The normative specification of the state transitions and outputs is given in Table 16-7. + +**Table 16-5 – OLT power management states** + +| State | Semantics | +|------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| AwakeForced | The OLT provides normal allocations to ONU i , forwards downstream traffic, and expects a response to every bandwidth grant. The OLT declares the LOB i defect on detection of the specified number of missed allocations. On transition into this state, the OLT sends a Sleep_Allow (OFF) PLOAM message, thus revoking its permission to the ONU to enter any low power mode. | +| AwakeFree | The OLT provides normal allocations to the ONU, forwards downstream traffic, and is ready to accept a power management transition indication from the ONU.
On transition into this state, the OLT sends a Sleep_Allow (ON) PLOAM message, thus granting the ONU a permission to enter any negotiated low power mode at its own discretion.
The OLT expects a response to every bandwidth grant, and in case of a missed allocation transitions to the AwakeForced state, where LOB i condition can be eventually declared.
There are two stable state combinations involving the AwakeFree state of the OLT state machine: the ONU state machine can be either in the ActiveFree state or in the ActiveHeld state. | +| LowPowerSleep
LowPowerDoze
LowPowerWatch | The OLT supports the ONU in a low power mode. The OLT provides normal allocations to the ONU but expects only intermittent responses from the ONU to bandwidth grants. In the LowPowerDoze state, the OLT forwards the downstream traffic; in the LowPowerSleep and LowPowerWatch states, the OLT may buffer the downstream traffic.
If timer Ter i expires before the OLT receives a burst from ONU i , the OLT recognizes a handshake violation and transitions to the AwakeForced state. | +| AlertedSleep
AlertedDoze
AlertedWatch | The OLT attempts to wake up the ONU. Having sent Sleep_Allow (OFF) message on transition to the state, the OLT sets the FWI bit in every allocation to the ONU along with the PLOAMu flag. The OLT forwards, discards or buffers downstream traffic for the ONU, just as it did during the immediately preceding LowPowerDoze/Sleep/Watch state. The OLT transitions to the AwakeForced state, if it receives a burst from the ONU that includes a Sleep_Request (Awake) PLOAM message, or if timer Talerted expires. | + +**Table 16-6 – OLT state machine inputs** + +| Input categories | Input | Semantics | +|------------------|-----------------------|---------------------------------------------------------------------------------------------| +| PLOAM events | Sleep_Request(Doze) | The ONU informs the OLT of its intent to exercise the doze power management mode. | +| | Sleep_Request(Sleep) | The ONU informs the OLT of its intent to exercise the cyclic sleep power management mode. | +| | Sleep_Request(WSleep) | The ONU informs the OLT of its intent to exercise the watchful sleep power management mode. | +| | Sleep_Request(Awake) | The ONU informs the OLT of its intent to remain at full power. | + +**Table 16-6 – OLT state machine inputs** + +| Input categories | Input | Semantics | +|------------------|-----------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------| +| Timer events | Ter 1 expiration | The event occurs only in the LowPowerDoze/Sleep/Watch states indicating the violation by the ONU of the provisioned low power timing parameters. | +| | Talerted expiration | The event occurs only in the AlertedDoze/Sleep/Watch states indicating the ONU's failure to wake-up upon OLT's demand. | +| Local events | Local wake-up indication, OLT-LWI | Local wake-up indication and its inverse indicate, respectively, the presence and the absence of a local stimulus to maintain the ONU at full power. | +| Interface events | Allocation Miss | No valid optical signal from ONU within a group of contiguous allocations to that ONU. | + +NOTE – The OLT-LWI event and its inverse are conceptually derived from the OLT's binary stimulus status level and correspond to the stimulus level change. The specific criteria for the local stimulus definition remain out of scope of this Recommendation. + +![Figure 16-2 – OLT state transition diagram (initial state circled). The diagram shows six states: (1) Awake Forced (initial state, circled), (2) Awake Free, (3) Low Power Sleep/Watch, (4) Alerted Sleep/Watch, (5) Low Power Doze, and (6) Alerted Doze. Transitions are triggered by events like SR (Awake), SR (Sleep/WSleep), SR (Doze), Teri expires, OLT-LWI, Miss, and FWI. States (1), (4), and (6) are 'tense' states, while (2), (3), and (5) are 'relaxed' states.](060648daa95345c57f019fc00ad75993_img.jpg) + +``` + +stateDiagram-v2 + [*] --> (1) Awake Forced + (1) --> (2) Awake Free + (2) --> (1) + (2) --> (3) Low Power Sleep/Watch : SR (Sleep/WSleep) + (2) --> (5) Low Power Doze : SR (Doze) + (3) --> (1) : Teri expires / SA(OFF) + (3) --> (2) : SR (Awake) + (3) --> (4) Alerted Sleep/Watch : OLT-LWI / SA(OFF) + (3) --> (3) : Miss, SR (Sleep/WSleep) + (4) --> (1) : SR (Awake) or Talerted expires + (4) --> (2) : SR (Awake) + (4) --> (3) : SR (Sleep/WSleep) + (4) --> (4) : Miss, SR (Sleep/WSleep) + (5) --> (1) : OLT-LWI, Miss / SA(OFF) + (5) --> (2) : SR (Awake) + (5) --> (6) Alerted Doze : Teri expires / SA(OFF) + (5) --> (5) : Miss, SR (Doze) + (6) --> (1) : SR (Awake) or Talerted expires + (6) --> (2) : SR (Awake) + (6) --> (5) : OLT-LWI / SA(OFF) + (6) --> (6) : Miss, SR (Doze) + (6) --> (4) : FWI + (1) --> (1) : SR (Awake) + (2) --> (2) : SR (Awake) + (3) --> (3) : SR (Sleep/WSleep) + (4) --> (4) : FWI + (5) --> (5) : SR (Doze) + (6) --> (6) : FWI + +``` + +Figure 16-2 – OLT state transition diagram (initial state circled). The diagram shows six states: (1) Awake Forced (initial state, circled), (2) Awake Free, (3) Low Power Sleep/Watch, (4) Alerted Sleep/Watch, (5) Low Power Doze, and (6) Alerted Doze. Transitions are triggered by events like SR (Awake), SR (Sleep/WSleep), SR (Doze), Teri expires, OLT-LWI, Miss, and FWI. States (1), (4), and (6) are 'tense' states, while (2), (3), and (5) are 'relaxed' states. + +**Figure 16-2 – OLT state transition diagram (initial state circled)** + +Notes: + +- (1) In this state diagram graph, vertices corresponding to states (1), (4) and (6) can be qualified as "tense" and form a tense subgraph, whereas vertices corresponding to states (2), (3) and (5) can be qualified as "relaxed" and form a relaxed subgraph. As a rule, an output PLOAM message is generated only on a state transition that crosses the subgraph boundary. +- (2) The use of the left-hand-side branch of the state machine depends on the power mode negotiations between the OLT and the ONU. If the Doze or Doze & Cyclic Sleep modes are selected, the SR(Sleep) + +condition applies, and the states are named (3) LowPowerSleep and (4) AlertedSleep. If the Watchful sleep mode is selected, the SR(WSleep) condition applies, and the states are named (3) LowPowerWatch and (4) AlertedWatch. However, all the transitions and state semantics remain exactly the same, which is the reason to combine them graphically. + +**Table 16-7 – OLT state transition and output table** + +| Inputs | OLT power management states | | | | | | +|-----------------------------|-----------------------------|-------------------|-------------------------------|-------------------------------|-------------------------------|-------------------------------| +| | (1) AwakeForced | (2) AwakeFree | (3) LowPower Sleep/Watch | (4) Alerted Sleep/Watch/FWI | (5) LowPower Doze | (6) Alerted Doze/FWI | +| SR (Awake) | * | * | → (2) | → (1) | → (2) | → (1) | +| SR (Sleep/WSleep) | *
/SA(OFF)
(Note 1) | → (3) | * | * | → (1)
/SA(OFF)
(Note 2) | → (1)
/SA(OFF)
(Note 2) | +| SR (Doze) | *
/SA(OFF)
(Note 1) | → (5) | → (1)
/SA(OFF)
(Note 2) | → (1)
/SA(OFF)
(Note 2) | * | * | +| Allocation miss | * | → (1)
/SA(OFF) | * | * | * | * | +| OLT-LWI ON | * | → (1)
/SA(OFF) | → (4)
/SA(OFF) | * | → (6)
/SA(OFF) | * | +| OLT-LWI OFF | → (2)
/SA(ON) | * | * | * | * | * | +| Talerted expiration | | | | → (1) | | → (1) | +| Ter i expiration | | | → (1)
/SA(OFF) | | → (1)
/SA(OFF) | | + +\* Indicates a self-transition. + A shaded cell means that the input is not applicable in the given state. + NOTE 1 – An exception from the subgraph rule; an output may help to stabilize the state machine in case the condition is caused by a lost SA(OFF) message. The output is not shown on the FSM diagram. + NOTE 2 – Direct transitions between Doze mode and Cyclic Sleep mode are disallowed. When the OLT receives a request to execute such a transition, it attempts to regain state machine synchronization by waking up the ONU. The transitions are not shown on the diagram for the sake of compactness. + NOTE 3 – This is a situation when the OLT initiates a wake-up, but the OLT-LWI is cleared before the ONU is awoken. In this case, the OLT, instead of cancelling the wake-up process and attempting to immediately revert to a power saving, insists on waking the ONU up with the intent to re-enter a power saving state via states AwakeForced and AwakeFree. + +## 16.4 Management transactions during low power mode + +The ONU can receive and act on downstream management traffic at any of the three channels described in clause 6.3, except when it is in a LowPower state (Asleep or Watch state) and has its receiver turned off. The OLT is responsible for understanding when the ONU can be expected to receive downstream management traffic, or to deal with the possibility that the ONU does not receive such traffic. + +If the ONU receives embedded OAM commands, such as DBRu or PLOAMu requests, when it cannot respond immediately, i.e., when it is in a LowPower state but has its receiver powered on, it ignores the commands. It is the OLT's responsibility to allow for extra response delays if it sends PLOAM or OMCI commands to an ONU that may be incapable of responding within the normal time. + +It is prudent for the OLT to force the ONU awake before conducting management transactions. + +The OLT is permitted to send unidirectional management transmissions at any time, including Profile, Deactivate\_ONU-ID, Disable\_Serial\_Number, and Sleep\_Allow PLOAM messages. The OLT must be prepared for the possibility that a sleeping ONU does not receive the transmission. + +For the purposes of this clause, an ONU becomes subject to power management only when it is in state O5. When the OLT understands that the ONU is not in state O5, for example, because the ONU is only newly discovered or has not yet registered, the normal ranging and assignment transactions occur without regard to the power saving state model. + +NOTE – It is possible that an ONU in states O1 or O2 might also wish to doze or sleep, as a way of conserving power while waiting for turn-up. This would involve a much simpler state model, and would require no exchange of information between OLT and ONU, externally visible merely as delayed discovery. Such a possibility is beyond the scope of this Recommendation. + +# Annex A + +## Hybrid error correction (HEC) decoding and scrambler sequence + +(This annex forms an integral part of this Recommendation.) + +## A.1 HEC decoding + +The hybrid error correction (HEC) structure is shown in Figure A.1. Note that the HEC is used in XG-PON in several places. In the XGTC-header, it is applied to a protected field of 19 bits, producing a total structure of 32 bits. In the BW-map and XGEM applications, it is applied to a protected field of 51 bits, producing a total structure of 64 bits. For the purposes of calculating the HEC, the 19-bit protected field is pre-pended with 32 zero bits (that are not transmitted). + +![Figure A.1 shows two diagrams of the Hybrid error correction (HEC) structure. The top diagram shows a 64-bit structure with bit positions 63 to 0. The bottom diagram shows a 32-bit structure with bit positions 31 to 0. Both diagrams show a 'Protected field' (51 bits in the top, 19 bits in the bottom), 'BCH(63, 12, 2) redundant bits' (12 bits), and an 'Even parity' bit (1 bit).](8edfc370769207831f060f44d2281084_img.jpg) + +The diagram illustrates two versions of the HEC structure. The top version is a 64-bit word with bit positions 63 to 0. The bottom version is a 32-bit word with bit positions 31 to 0. Both versions consist of three parts: a protected field, BCH(63, 12, 2) redundant bits, and an even parity bit. In the top version, the protected field is 51 bits (bits 63 to 13), the redundant bits are 12 bits (bits 12 to 1), and the even parity bit is 1 bit (bit 0). In the bottom version, the protected field is 19 bits (bits 31 to 13), the redundant bits are 12 bits (bits 12 to 1), and the even parity bit is 1 bit (bit 0). + +Figure A.1 shows two diagrams of the Hybrid error correction (HEC) structure. The top diagram shows a 64-bit structure with bit positions 63 to 0. The bottom diagram shows a 32-bit structure with bit positions 31 to 0. Both diagrams show a 'Protected field' (51 bits in the top, 19 bits in the bottom), 'BCH(63, 12, 2) redundant bits' (12 bits), and an 'Even parity' bit (1 bit). + +G.987.3(10)\_FA.1 + +**Figure A.1 – Hybrid error correction structure, showing details of the 13-bit header error control field** + +The HEC is a double error correcting, triple error detecting code. It is composed of two parts. The first part is a BCH(63, 12, 2) code. The generator polynomial for this code is $x^{12} + x^{10} + x^8 + x^5 + x^4 + x^3 + 1$ . This code is applied to the protected field (which is 51 bits), so that the 63-bit result is divisible by the generator polynomial. The properties of this code are such that every single error and every double error has a unique 12-bit syndrome. Thus, all such errors can be corrected. Also, triple errors can produce syndromes that match double error syndromes or illegal codes, but there is no triple error syndrome that matches a single error syndrome. It is this last property that permits the use of a single parity bit to detect and exclude triple errors. + +The table of error syndromes for this code is given in Table A.1. Note that bit position 63 is the first bit of the protected 51 bit field, and bit position 1 is the next to last bit of the HEC. Position 0 (the last bit) is reserved for the even parity bit. For the short structure case, the first bit of the protected 19-bit field is in bit position 31. + +**Table A.1 – HEC error syndromes** + +| Error bit position | Syndrome (base 16) | Error bit position | Syndrome (base 16) | Error bit position | Syndrome (base 16) | Error bit position | Syndrome (base 16) | +|--------------------|--------------------|--------------------|--------------------|--------------------|--------------------|--------------------|--------------------| +| 63 | A9C | 47 | A09 | 31 | B04 | 15 | 1DD | +| 62 | 54E | 46 | F98 | 30 | 582 | 14 | A72 | +| 61 | 2A7 | 45 | 7CC | 29 | 2C1 | 13 | 539 | +| 60 | BCF | 44 | 3E6 | 28 | BFC | 12 | 800 | +| 59 | F7B | 43 | 1F3 | 27 | 5FE | 11 | 400 | +| 58 | D21 | 42 | A65 | 26 | 2FF | 10 | 200 | +| 57 | C0C | 41 | FAE | 25 | BE3 | 9 | 100 | + +**Table A.1 – HEC error syndromes** + +| Error bit position | Syndrome (base 16) | Error bit position | Syndrome (base 16) | Error bit position | Syndrome (base 16) | Error bit position | Syndrome (base 16) | +|--------------------|--------------------|--------------------|--------------------|--------------------|--------------------|--------------------|--------------------| +| 56 | 606 | 40 | 7D7 | 24 | F6D | 8 | 080 | +| 55 | 303 | 39 | 977 | 23 | D2A | 7 | 040 | +| 54 | B1D | 38 | E27 | 22 | 695 | 6 | 020 | +| 53 | F12 | 37 | D8F | 21 | 9D6 | 5 | 010 | +| 52 | 789 | 36 | C5B | 20 | 4EB | 4 | 008 | +| 51 | 958 | 35 | CB1 | 19 | 8E9 | 3 | 004 | +| 50 | 4AC | 34 | CC4 | 18 | EE8 | 2 | 002 | +| 49 | 256 | 33 | 662 | 17 | 774 | 1 | 001 | +| 48 | 12B | 32 | 331 | 16 | 3BA | 0 | N/A (parity) | + +Because there are 63 unique single error syndromes, there are 1953 unique double error syndromes. As there are 4095 possible syndromes in the 12-bit space, this leaves 2079 codes that are not used. These unused codes are considered illegal, in that they can only result from three or more errors. + +The second part of the HEC is a simple parity bit. This parity bit is set so that the total number of ones in the protected field+HEC is an even number. This parity then indicates if an odd number of errors have occurred in the header. Note that the BCH code does not include the parity bit in its calculations, but the parity bit does include the BCH code in its calculation. + +A few examples of valid 64-bit HEC protected structures are given in Table A.2. These can be used to test implementations of the encoding and decoding processes. + +**Table A.2 – Valid 64 bit HEC-protected structures** + +| | | | +|------------------|------------------|------------------| +| 58472D504F4E0A55 | 204B616E692C1748 | 69726F616B690C8B | +| 2077617320701574 | 204A6F6520530247 | 204D756B61690A22 | +| 726F64756365128E | 6D6974682C201A23 | 2C20446176651A73 | +| 64207468616E1A18 | 5269636861720A6E | 20486F6F642C0F79 | +| 6B7320746F201705 | 6420476F6F64176E | 20576569204C04F2 | +| 416E6E6120430915 | 736F6E2C20440F00 | 696E2C20616E05E9 | +| 75692C204661159F | 656E6973204B1780 | 64206F6620631C47 | +| 6272696365200372 | 686F74696D731F44 | 6F757273652C0405 | +| 426F75726761033D | 6B792C205975155F | 204672616E6B0601 | +| 72742C204A751760 | 616E7169752005E8 | 20456666656E1897 | +| 6E2D696368690A8 | 4C756F2C204817D2 | 6265726765720486 | + +A few examples of valid 32-bit HEC protected structures are given in Table A.3. + +**Table A.3 – Valid 32-bit HEC-protected structures** + +| | | | +|----------|----------|----------| +| 58470E66 | 696E07CC | 6B201FCB | +| 2D5011A6 | 20731B4E | 4861190A | +| 4F4E03DA | 7069115E | 6A6411EA | +| 20680AD7 | 746518A3 | 75631541 | +| 6170070D | 206F1E9B | 7A650166 | +| 70651D5D | 66200F13 | 6E691F63 | +| 6E651360 | 4D61022E | 612E011B | +| 642018D4 | 72650A9A | 2020162F | + +The HEC can be decoded at the receiver by calculating the syndrome and the parity at the receiver, and then applying the logic described below. + +Table A.4 represents the HEC verification results, showing the maximum likelihood combination of underlying events and the usability of the header (after applicable error-correction) for each combination of the BCH block code decoding and parity check outcomes. + +**Table A.4 – HEC verification (maximum likelihood event/usability of the field)** + +| BCH block decoding outcome | Parity check outcome | | +|----------------------------|---------------------------------------------------------------------------------------|------------------------------------------------------------------| +| | Pass | Fail | +| No errors | Error free/
Protected field OK | Parity bit error/
Protected field OK | +| Single error | Single block code error +
parity error/
Protected field correctable
with BCH | Single block code error/
Protected field correctable with BCH | +| Double error | Double block code error/
Protected field correctable
with BCH | Triple block code error/
Protected field uncorrectable | +| Uncorrectable | Multiple bit errors/
Protected field uncorrectable | Multiple bit errors/
Protected field uncorrectable | + +## A.2 Scrambler sequence + +The first 256 bits from the scrambler sequence is given in Table A.5 in binary and hexadecimal representation (this assumes that the superframe counter is equal to zero). + +**Table A.5 – Scrambler sequence example** + +| | | | | | | | | | | | | +|------|------|------|------|------|------|------|------|------|------|------|------| +| 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | +| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | +| 0001 | 1111 | 1100 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0000 | 0011 | 1111 | +| 1 | F | C | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | F | +| 1000 | 0000 | 0000 | 0111 | 1111 | 0000 | 0000 | 0000 | 0111 | 1111 | 0000 | 0000 | +| 8 | 0 | 0 | 7 | F | 0 | 0 | 0 | 7 | F | 0 | 0 | +| 0000 | 0000 | 0000 | 0000 | 0000 | 0001 | 0000 | 0010 | 0000 | 0000 | 0001 | 1111 | +| 0 | 0 | 0 | 0 | 0 | 1 | 0 | 2 | 0 | 0 | 1 | F | +| 1100 | 0000 | 0000 | 0010 | 0000 | 0100 | 0000 | 0000 | 0111 | 1111 | 0000 | 0000 | +| C | 0 | 0 | 2 | 0 | 4 | 0 | 0 | 7 | F | 0 | 0 | +| 0000 | 0011 | 1111 | 1000 | | | | | | | | | +| 0 | 3 | F | 8 | | | | | | | | | + +# Annex B + +## Forward error correction using shortened Reed-Solomon codes + +(This annex forms an integral part of this Recommendation.) + +The material presented in this annex is based on [ITU-T G.709]. + +## B.1 Polynomial representation over Galois field + +The binary primitive polynomial $f(x) = x^8 + x^4 + x^3 + x^2 + 1$ with a root $\alpha$ , $f(\alpha) = 0$ , defines a finite field: + +$$GF(2^8) = \{0, 1, \alpha^1, \dots, \alpha^{254}\}$$ + +A vector of $n$ 8-bit symbols: + +$$(B_{n-1}, B_{n-2}, \dots, B_1, B_0)$$ + +can be represented as a polynomial with the coefficients from $GF(2^8)$ : + +$$B(z) = B_{n-1}(\alpha)z^{n-1} + B_{n-2}(\alpha)z^{n-2} + B_1(\alpha)z^1 + B_0(\alpha),$$ + +where: + +$$B_j(\alpha) = b_{7,j} \cdot \alpha^7 + b_{6,j} \cdot \alpha^6 + \dots + b_{1,j} \cdot \alpha^1 + b_{0,j} \cdot \alpha^0$$ + +and $(b_{7,j}, b_{6,j}, \dots, b_{0,j})$ are the bits of the symbol $B_j$ . + +## B.2 Construction of RS(248, 232) codeword + +The generator polynomial is: + +$$G(z) = \prod_{i=0}^{15} (z - \alpha^i)$$ + +The FEC codeword consists of 232 information bytes and 16 parity bytes and is represented by the polynomial over $z$ with coefficients from $GF(2^8)$ : + +$$C(z) = I(z) \cdot z^{16} + R(z)$$ + +The information bytes are represented by: + +$$I(z) = D_{231} \cdot z^{231} + D_{230} \cdot z^{230} + \dots + D_0 \cdot z^0$$ + +where $D_j$ ( $j = 0$ to 231) is the information byte represented as: + +$$D_j = d_{7,j} \cdot \alpha^7 + d_{6,j} \cdot \alpha^6 + \dots + d_{1,j} \cdot \alpha^1 + d_{0,j}$$ + +The polynomial representation of the parity symbols: + +$$R(z) = R_{15} \cdot z^{15} + R_{14} \cdot z^{14} + \dots + R_1 \cdot z^1 + R_0$$ + +is calculated as: + +$$R(z) = I(z) \cdot z^{16} \bmod G(z)$$ + +where "mod" is the modulo calculation over the code generator polynomial $G(z)$ with elements out of the $GF(2^8)$ . + +NOTE – If the number $L$ of the information bytes available for a codeword is less than 232, then $(L - 232)$ higher order coefficients of $I(z)$ are set to all-zeros and are not transmitted over the communication link. + +The transmission order is represented in Figure B.1: + +![Figure B.1: Transmission order of the RS(248, 232) codeword. The diagram shows a sequence of bytes in a codeword, indexed from 1 to 248. The sequence is: D231, D230, D229, ..., Dj, ..., D1, D0, R15, R14, ..., Rj, ..., R1, R0. Above the sequence, an arrow labeled 'Transmission order within FEC codeword' points from left to right. Below the sequence, two callouts show the bit-level representation of bytes Dj and Rj. For Dj, the bits are d7j, d6j, d5j, d4j, d3j, d2j, d1j, d0j (from left to right). For Rj, the bits are r7j, r6j, r5j, r4j, r3j, r2j, r1j, r0j (from left to right). The source text 'G.987.3(10)-Amd.1(12)_FB.1' is at the bottom right.](0b2ee589f5c7802f3d332f421340cae1_img.jpg) + +Figure B.1: Transmission order of the RS(248, 232) codeword. The diagram shows a sequence of bytes in a codeword, indexed from 1 to 248. The sequence is: D231, D230, D229, ..., Dj, ..., D1, D0, R15, R14, ..., Rj, ..., R1, R0. Above the sequence, an arrow labeled 'Transmission order within FEC codeword' points from left to right. Below the sequence, two callouts show the bit-level representation of bytes Dj and Rj. For Dj, the bits are d7j, d6j, d5j, d4j, d3j, d2j, d1j, d0j (from left to right). For Rj, the bits are r7j, r6j, r5j, r4j, r3j, r2j, r1j, r0j (from left to right). The source text 'G.987.3(10)-Amd.1(12)\_FB.1' is at the bottom right. + +**Figure B.1 – Transmission order of the RS(248, 232) codeword** + +## B.3 Construction of RS(248, 216) codeword + +The generator polynomial is: + +$$G(z) = \prod_{i=0}^{31} (z - \alpha^i)$$ + +The FEC codeword consists of 216 information bytes and 32 parity bytes and is represented by the polynomial over $z$ with coefficients from $GF(2^8)$ : + +$$C(z) = I(z) \cdot z^{32} + R(z)$$ + +The information bytes are represented by: + +$$I(z) = D_{215} \cdot z^{215} + D_{214} \cdot z^{214} + \dots + D_0 \cdot z^0$$ + +where $D_j$ ( $j = 0$ to 215) is the information byte represented as: + +$$D_j = d_{7j} \cdot \alpha^7 + d_{6j} \cdot \alpha^6 + \dots + d_{1j} \cdot \alpha + d_{0j}$$ + +The polynomial representation of the parity symbols: + +$$R(z) = R_{31} \cdot z^{31} + R_{30} \cdot z^{30} + \dots + R_1 \cdot z^1 + R_0$$ + +is calculated as: + +$$R(z) = I(z) \cdot z^{32} \bmod G(z)$$ + +where "mod" is the modulo calculation over the code generator polynomial $G(z)$ with elements out of the $GF(2^8)$ . + +The transmission order is represented in Figure B.2: + +![Diagram showing the transmission order of an RS(248, 216) codeword. The main row shows symbols D_215, D_214, ..., D_j, ..., D_1, D_0, R_31, R_32, ..., R_j, ..., R_3, R_1, R_0 with indices 1, 2, ..., 215, 216, 217, 218, ..., 246, 247, 248. Below D_j, an arrow points to a row of data symbols d_7j, d_6j, d_5j, d_4j, d_3j, d_2j, d_1j, d_0j. Below R_j, an arrow points to a row of parity symbols r_7j, r_6j, r_5j, r_4j, r_3j, r_2j, r_1j, r_0j.](708e7ef81dbf726e558047afe57d6ff7_img.jpg) + +Transmission order within FEC codeword + +| | | | | | | | | | | | | | | | +|-----------|-----------|-----|-------|-----|-------|-------|----------|----------|-----|-------|-----|-------|-------|-------| +| 1 | 2 | ... | $D_j$ | ... | 215 | 216 | 217 | 218 | ... | $R_j$ | ... | 246 | 247 | 248 | +| $D_{215}$ | $D_{214}$ | ... | $D_j$ | ... | $D_1$ | $D_0$ | $R_{31}$ | $R_{32}$ | ... | $R_j$ | ... | $R_3$ | $R_1$ | $R_0$ | + + + +| | | | | | | | | +|----------|----------|----------|----------|----------|----------|----------|----------| +| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| $d_{7j}$ | $d_{6j}$ | $d_{5j}$ | $d_{4j}$ | $d_{3j}$ | $d_{2j}$ | $d_{1j}$ | $d_{0j}$ | + + + +| | | | | | | | | +|----------|----------|----------|----------|----------|----------|----------|----------| +| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +| $r_{7j}$ | $r_{6j}$ | $r_{5j}$ | $r_{4j}$ | $r_{3j}$ | $r_{2j}$ | $r_{1j}$ | $r_{0j}$ | + +G.987.3(10)-Amd.1(12)\_FB.2 + +Diagram showing the transmission order of an RS(248, 216) codeword. The main row shows symbols D\_215, D\_214, ..., D\_j, ..., D\_1, D\_0, R\_31, R\_32, ..., R\_j, ..., R\_3, R\_1, R\_0 with indices 1, 2, ..., 215, 216, 217, 218, ..., 246, 247, 248. Below D\_j, an arrow points to a row of data symbols d\_7j, d\_6j, d\_5j, d\_4j, d\_3j, d\_2j, d\_1j, d\_0j. Below R\_j, an arrow points to a row of parity symbols r\_7j, r\_6j, r\_5j, r\_4j, r\_3j, r\_2j, r\_1j, r\_0j. + +**Figure B.2 – Transmission order of the RS(248, 216) codeword** + +# Annex C + +## Secure mutual authentication via OMCI + +(This annex forms an integral part of this Recommendation.) + +This method employs the enhanced security control managed entity (ME) defined in clause 9.13.11 of [ITU-T G.988] to perform a three-step hash-based authentication. After ONU registration, the OLT can initiate the mutual authentication process by writing an OLT random challenge. The details of the related ME and authentication state diagram are specified in clause 9.13.11 of [ITU-T G.988]. + +Following successful mutual authentication (or re-authentication) via OMCI, the OLT and the ONU share a master session key (MSK) defined as: + +$$\text{MasterSessionKey} = \text{SelectedHashFunction}(\text{PSK}, \text{OLT\_random\_challenge} \mid \text{ONU\_random\_challenge}),$$ + +where $\text{SelectedHashFunction}()$ is the hash function selected by the ONU from the list supplied by the OLT, PSK is the pre-shared secret in OMCI-based authentication, and " $\mid$ " denotes byte concatenation. + +Leaving this mutual authentication, the MSK is ready to be used in the key derivation specified in clause 15.3. + +# Annex D + +## Secure mutual authentication based on IEEE 802.1X + +(This annex forms an integral part of this Recommendation.) + +## D.1 Introduction + +IEEE 802.1X is a protocol for link layer authentication, port access control, and key establishment. The particular credentials used for authentication (e.g., passwords, public keys, etc.) are not part of the [IEEE 802.1X] standard. Instead, the IEEE 802.1X frames encapsulate packets of the IETF extensible authentication protocol (EAP) which supports a variety of credential types (e.g., passwords, RSA-based public keys, smart cards etc.) as well as mechanisms for negotiating authentication capabilities and policies. IEEE 802.1X and EAP are specified in [IEEE 802.1X], [IETF RFC 3748], and [IETF RFC 5247]. + +Note that the IEEE 802.1X features supported in clauses 9.3.14 to 9.3.17 of [ITU-T G.988] are intended to permit a trusted ONU to authenticate untrusted CPEs. They are not related to the IEEE 802.1X authentication as described in this annex. + +### D.1.1 Network model for authentication in [IEEE 802.1X] + +Figure D.1 shows the general architecture of [IEEE 802.1X] authentication for XG-PON. + +![Diagram of IEEE 802.1X-based authentication in XG-PON. It shows two ONUs connected to an OLT within an ODN (Optical Distribution Network). The OLT is connected to an authentication server within a secured network. TC layer communication is shown between the ONUs and the OLT. The authentication server is labeled G.987.3(10)_FD.1.](4a9454b4354535e1b61423084da1424b_img.jpg) + +The diagram illustrates the network architecture for IEEE 802.1X-based authentication in XG-PON. On the left, an oval labeled 'ODN' contains two 'ONU' boxes and an 'OLT' box. Lines labeled 'TC layer communication' connect the ONUs to the OLT. The OLT is connected to a 'Secured network' oval on the right, which contains a cylinder representing an 'Authentication server'. A line connects the OLT to the authentication server. The label 'G.987.3(10)\_FD.1' is at the bottom right. + +Diagram of IEEE 802.1X-based authentication in XG-PON. It shows two ONUs connected to an OLT within an ODN (Optical Distribution Network). The OLT is connected to an authentication server within a secured network. TC layer communication is shown between the ONUs and the OLT. The authentication server is labeled G.987.3(10)\_FD.1. + +**Figure D.1 – [IEEE 802.1X]-based authentication in XG-PON** + +In this model: + +- ONUs maintain physically insecure TC-layer connectivity to the OLT across the ODN. +- The OLT maintains physically-secure or logically-secure connectivity to an authentication server. Communication between the OLT and the authentication server is typically (but not necessarily) conducted using a policy protocol such as RADIUS. The authentication server might be physically co-located with the OLT. + +The IEEE 802.1X protocol is used to perform mutual authentication between the OLT (which acts in the role of the IEEE 802.1X "authenticator") and ONU (the IEEE 802.1X "supplicant"). Following successful authentication, the OLT provides full network connectivity to the authenticated ONU. The successful authentication process results in the creation of a master session key (MSK) which is then used to secure the subsequent key derivation between the OLT and the ONU. + +### D.1.2 Credentials for XG-PON authentication with [IEEE 802.1X] + +A variety of authentication credentials are supported by the EAP mechanism of [IEEE 802.1X]. Each supported credential type is associated with an EAP method name and EAP type. An up-to-date list of credentials and associated EAP types is maintained at . + +The XG-PON protocols enable the use of any EAP-type, depending on the local operator's policy. However, an EAP-type which does not support mutual authentication and master key generation cannot be used for XG-PON. + +To guarantee interoperability, all XG-PON OLTs and ONUs supporting [IEEE 802.1X] authentication implement EAP-GPSK [IETF RFC 5433] providing user authentication based on "pre-shared" keys (i.e., passwords that might be distributed to users via telephone or some other out-of-band mechanism). The user identifiers and associated pre-shared keys are provisioned into both the ONU devices and the authentication server in a manner determined by each implementation. + +Some operators might be interested in device authentication based on public key cryptography. OLTs and ONUs in such deployments implement EAP-TLS [IETF RFC 5216]. The user identifiers and associated certificates are provisioned into both the ONU devices and the authentication server in a manner determined by each implementation. + +## D.2 Stack model for XG-PON authentication using [IEEE 802.1X] + +[IEEE 802.1X] logically resides above the XGEM client and below the MAC clients in the XG-PON stack (on both the ONU and OLT). + +![Stack model of IEEE 802.1X authentication diagram showing layers from IEEE 802.1X down to XG-PON PMD.](7818b1bd115c04ee738bcf90f51d945b_img.jpg) + +The diagram illustrates the protocol stack for XG-PON authentication. At the top, three boxes represent the entities above the XG-PON TC layer: PLOAM, OMCI (ITU-T G.988), and XGEM client. The XGEM client is connected to the IEEE 802.1X entity. Below these is the XG-PON TC layer, which contains the XGTC service adaptation sublayer. Inside the XGTC service adaptation sublayer, there are three components: an OMCI Adapter (connected to the OMCI box), an XGEM TC Adapter (connected to the XGEM client box), and a DBA control box. The XGEM TC Adapter is further divided into a Control channel and Other payload. Below the XGTC service adaptation sublayer is the XGTC framing sublayer, followed by the XGTC PHY adaptation Sublayer, and finally the XG-PON PMD (ITU-T G.987.2) at the bottom. + +Stack model of IEEE 802.1X authentication diagram showing layers from IEEE 802.1X down to XG-PON PMD. + +G.987.3(10)\_FD.2 + +**Figure D.2 – Stack model of IEEE 802.1X authentication** + +Before authentication, [IEEE 802.1X] blocks user Ethernet packets and does not pass them to the MAC clients. After the ONU and OLT have successfully authenticated, frames are passed between the MAC clients and the TC layer. + +Frames are freely exchanged at the PLOAM and OMCI layers even when the ONU is unauthenticated – as these reside lower in the stack than the IEEE 802.1X entity. + +## D.3 Behaviour at network entry + +After the ONU activation process is complete (see clause 12) and before any live traffic can be transmitted from the ONU, the OLT may start the IEEE 802.1X procedure (depending on the local policy). + +Subsequent to ONU registration and prior to any user traffic exchange, the OLT implements the IEEE 802.1X exchange to authenticate the ONU (by sending the extensible authentication protocol over LAN (EAPOL) request identity frame to the authenticating ONU). The OLT discards all Ethernet packet traffic originating from the ONU except for EAPOL frames required for IEEE 802.1X authentication. Only after the successful completion of the IEEE 802.1X authentication, the OLT accepts all traffic generated by the ONU. Transmission or reception of an EAP-Success message delimits the successful completion of authentication. + +The encapsulation of IEEE 802.1X EAPOL packets in XGEM frames is illustrated in Figure D.3. + +![Diagram showing the encapsulation of an EAPOL packet within an XGEM frame. The diagram illustrates three layers: Ethernet over XGEM, Ethernet frame, and EAPOL packet. The Ethernet over XGEM layer consists of an XGEM header and an XGTC payload. The Ethernet frame layer includes Destination (0180C2-000003), Source, Type (88-8E), Data, and FCS fields. The EAPOL packet layer includes Protocol version (1), Packet type (0-EAP packet, 1-EAPOL start, 2-EAPOL logoff, 3-EAPOL key), Packet body length, and Packet body fields. Arrows indicate the mapping of the Ethernet frame and EAPOL packet into the XGTC payload.](b0b9bc3067d012eb2fa3539217b9c34d_img.jpg) + +| | | | | | | +|--------------------|--|--------------------------------|------------------------------------------------------------------------------|--------------------|-------------| +| Ethernet over XGEM | | XGTC payload | | | | +| Ethernet frame | | Destination
(0180C2-000003) | Source | Type
(88-8E) | Data | +| EAPOL packet | | Protocol version
(1) | Packet type
(0-EAP packet, 1-EAPOL start,
2-EAPOL logoff, 3-EAPOL key) | Packet body length | Packet body | + +G.987.3(10)\_FD.3 + +Diagram showing the encapsulation of an EAPOL packet within an XGEM frame. The diagram illustrates three layers: Ethernet over XGEM, Ethernet frame, and EAPOL packet. The Ethernet over XGEM layer consists of an XGEM header and an XGTC payload. The Ethernet frame layer includes Destination (0180C2-000003), Source, Type (88-8E), Data, and FCS fields. The EAPOL packet layer includes Protocol version (1), Packet type (0-EAP packet, 1-EAPOL start, 2-EAPOL logoff, 3-EAPOL key), Packet body length, and Packet body fields. Arrows indicate the mapping of the Ethernet frame and EAPOL packet into the XGTC payload. + +**Figure D.3 – EAPOL packet encapsulation in XGEM** + +Once the IEEE 802.1X based mutual authentication succeeds, the OLT and the authenticated ONU share a common secret value that is at least 64 octets in length, depending on the EAP-type. The 16 most significant octets of the shared secret are used as an MSK for the key derivation procedure specified in clause 15.3. + +# Annex E + +## PON-ID maintenance + +(This annex forms an integral part of this Recommendation.) + +The implementation of this annex is optional. The ITU-T G.987 XG-PON systems, OLTs, or ONUs that are required to support the provision of the present annex are herein referred to as compliant. An ONU's compliance with this annex can be discovered via OMCI (see clause 9.1.1 of [ITU-T G.988]). + +## E.1 Introduction + +This annex contains provisions enabling field personnel to retrieve a PON port identifier and an indication of the launched power on the network, adapted from the optical layer supervision concept defined in [b-ITU-T G.984.2], and applied to the optical module capabilities of XG-PON. The specified method defines the format of the PON-ID structure. Comparison of the locally measured optical power and the image of the source launched power coded in the PON-ID field should give operators a means to differentiate fibre plant loss from variations in launched power. Coding commonality with existing power measurements in [ITU-T G.988] is intended, as well as alignment with [b-SFF SFF8472] which defines the information available at the received signal strength indicator (RSSI) interface of opto-electrical converters of interest in OLT implementations. + +## E.2 PON-ID structure + +A system compliant with this annex shall support a PON-ID structure according to the following definition, which supersedes clause 10.1.1.3. + +![Diagram of the PON-ID structure showing a hierarchy of fields. The top level is 'PON-ID structure 8 bytes', which branches into 'PIT 8 bits', 'PON-ID 32 bits', 'TOL 11 bits', and 'HEC 13 bits'. The 'PIT 8 bits' field is further partitioned into 'RE 1 bit', 'ODN Class 3 bits', and 'Reserved 4 bits'.](f59dafee4c3bbc563111e5b1b6048c3d_img.jpg) + +The diagram illustrates the PON-ID structure. At the top, a box labeled "PON-ID structure 8 bytes" has arrows pointing to four fields: "PIT 8 bits", "PON-ID 32 bits", "TOL 11 bits", and "HEC 13 bits". Below the "PIT 8 bits" field, an arrow points to a sub-partition containing three fields: "RE 1 bit", "ODN Class 3 bits", and "Reserved 4 bits". + +G.987.3(10)-Amd.1(12)\_FE.1 + +Diagram of the PON-ID structure showing a hierarchy of fields. The top level is 'PON-ID structure 8 bytes', which branches into 'PIT 8 bits', 'PON-ID 32 bits', 'TOL 11 bits', and 'HEC 13 bits'. The 'PIT 8 bits' field is further partitioned into 'RE 1 bit', 'ODN Class 3 bits', and 'Reserved 4 bits'. + +Figure E.1 – PON-ID structure + +The PON-ID structure (see Figure E.1) contains the following fields: + +**PIT**, or **PON-ID Type** (8 bits, static, provisioned by the operator): an indication of the ODN architecture, the source of the reported launch power and the ODN class. The PON-ID type (PIT) field is further partitioned as follows: + +**RE flag** (1 bit): indicates whether the transmit optical level (TOL) field contains the launch power of the OLT or of a reach extender; + +**ODN Class** (3 bits): Identifies the nominal optical parameters of the transceiver according to ODN class as defined in [ITU-T G.987.2] with the following coding. + +| Code value | ODN budget class | +|------------|------------------| +| 000 | N1 | +| 001 | N2/N2a | +| 010 | N2b | +| 011 | E1 | +| 100 | E2/E2a/D | +| 101 | E2b | +| 110 | B+ | +| 111 | C+ | + +**Reserved** (4 bits): bits reserved for future use; set to 0000 unless otherwise specified. + +**PON-ID** (32 bits, static, provisioned by the operator): any value of interest to the operator, which may, for example, reflect the established logical address plan; + +**TOL** (11 bits, dynamic, maintained by the system): transmit optical level, an indication of the current transceiver launch power of the appropriate network element. Its value is an integer referred to 1 $\mu\text{W}$ (i.e., the value zero represents $-30\text{ dBm}$ ), with 0.1 dB granularity. The 0x7FF default value indicates that TOL is not supported on the given PON interface. The coding is adapted to support the entire suite of specified XG-PON ODN classes (N1, N2a, N2b, E1, E2a, E2b) and reach extender options, covering the transceiver launch power range from $+2\text{ dBm}$ to $+16.5\text{ dBm}$ . + +**HEC** (13 bits, dynamic inserted by the transmitter): a combination of a BCH(63,12,2) code operating on the 63 initial bits of the SFC structure and a single parity bit. The details of HEC construction and verification are specified in Annex A of this Recommendation. + +# Annex F + +## Extended rogue ONU mitigation capabilities + +(This annex forms an integral part of this Recommendation.) + +The implementation of this annex is mandatory for all new implementations. The ITU-T G.987 XG-PON systems, OLTs, or ONUs that support the provision of the present annex are herein referred to as compliant. + +## F.1 Introduction + +The present annex contains provisions that allow an XG-PON system to mitigate the condition when an ONU exhibits rogue behaviour at the discovery stage of the activation process, before its serial number is discovered and before it is assigned an ONU-ID. The provisions of this annex allow the OLT, upon detecting rogue interference on the PON, to selectively disable the ONUs at the discovery stage of the activation process. + +## F.2 Extra codepoint of disable PLOAM message type + +A compliant OLT and a compliant ONU support a Disable\_Serial\_Number PLOAM message, whose definition is modified with respect to the summary of clause 11.3.1 and format specification of clause 11.3.3.5 as follows. + +| Message Type ID | Message name | Function | Trigger | Effect of receipt | +|-----------------|-----------------------|----------------------------------------------------------|--------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0x06 | Disable_Serial_Number | Broadcast message to disable/enable a specified ONU set. | At the OLT's discretion. |

Disable options: Moves the specified ONU, the ONU in the discovery stage, or all ONUs to the Emergency Stop state. The disabled ONU is prohibited from transmitting.

Enable options: Moves the specified ONU or all ONUs in the Emergency Stop state to the Initial state. The enabled ONU discards the TC layer configuration and restarts the activation process, as specified in clause 12.

No Acknowledgement.

| + +The modified Disable\_Serial\_Number message has the following format. + +| Octet | Content | Description | +|-------|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1-2 | 0x03FF | Broadcast ONU-ID. | +| 3 | 0x06 | Message type ID "Disable_Serial_Number". | +| 4 | SeqNo | Broadcast PLOAM sequence number. | +| 5 | Disable/enable | 0xFF – The ONU with this serial number is denied upstream access.
0x00 – The ONU with this serial number is allowed upstream access.
0x0F – All ONUs are denied upstream access. The content of bytes 6-13 is ignored.
0x3F – Disable_Discovery: the ONUs in O2-3 state are denied upstream access. The content of bytes 6-13 is ignored.
0xF0 – All ONUs are allowed upstream access. | +| 6-9 | Vendor-ID | ONU Vendor-ID code, a four-character combination discovered at SN acquisition. | +| 10-13 | VSSN | Vendor-specific serial number, a four-byte unsigned integer discovered at SN acquisition. | +| 14-40 | Padding | Set to 0x00 by the transmitter; treated as "don't care" by the receiver. | +| 41-48 | MIC | Message integrity check. | + +## F.3 Extra transition of the ONU activation cycle state transition diagram + +### F.3.1 State transition diagram + +A compliant system supports the standard ONU activation state transition diagram as reproduced in Figure F.1, where the Disable SN request event has state-specific definition. + +![Figure F.1 – The modified ONU activation state diagram. This state transition diagram shows seven states: Initial state (O1), Serial Number state (O2-3), Ranging state (O4), Operation state (O5), Intermittent LODS state (O6), Emergency Stop state (O7), and Suspension state (O8). Transitions are triggered by events like 'Downstream synchronization attained', 'Assign_ONU-ID PLOAM', 'TO1 timer expires', 'Ranging_Time PLOAM', 'Loss of downstream synchronization', 'Deactivate ONU-ID request', 'Disable SN request', 'Enable SN request', and 'TO2 timer expires'. The diagram includes detailed descriptions for each state and numerous transition arrows between them.](baf8e707713cfcf1fd4e6aa38dd94597_img.jpg) + +G.987.3(10)-Amd.1(12)\_FF.1 + +Figure F.1 – The modified ONU activation state diagram. This state transition diagram shows seven states: Initial state (O1), Serial Number state (O2-3), Ranging state (O4), Operation state (O5), Intermittent LODS state (O6), Emergency Stop state (O7), and Suspension state (O8). Transitions are triggered by events like 'Downstream synchronization attained', 'Assign\_ONU-ID PLOAM', 'TO1 timer expires', 'Ranging\_Time PLOAM', 'Loss of downstream synchronization', 'Deactivate ONU-ID request', 'Disable SN request', 'Enable SN request', and 'TO2 timer expires'. The diagram includes detailed descriptions for each state and numerous transition arrows between them. + +**Figure F.1 – The modified ONU activation state diagram** + +In state O2-3, Disable SN requests is generated upon receipt of Disable\_Serial\_Number PLOAM message with Disable specific SN, Disable All, or Disable\_Discovery options. In states O4 and O5, the Disable SN requests is generated upon receipt of Disable\_Serial\_Number PLOAM message with Disable specific SN or Disable All options, but is not generated upon receipt of Disable\_Serial\_Number PLOAM message with Disable\_Discovery option. + +### F.3.2 ONU state transition table + +In addition to the events and transitions of Table 12-1 in clause 12.2.4, a compliant system supports a transition from the Serial Number (O2-3) state to the Emergency Stop (O7) state upon receipt of the Disable\_Serial\_Number PLOAM message with Disable\_Discovery option. + +| Event | ONU activation state | | | | | | | +|-----------------------------------------------------|----------------------|--------------------|------------|--------------|----------------------|-------------------|---------------| +| | Initial O1 | Serial Number O2-3 | Ranging O4 | Operation O5 | Intermittent LODS O6 | Emergency Stop O7 | Suspension O8 | +| Receive Disable PLOAM
– Disable_Discovery option | – | ==> O7; | – | – | – | – | – | + +# Appendix I + +## Downstream line data pattern conditioning + +(This appendix does not form an integral part of this Recommendation.) + +This appendix describes a few reasons for and methods to control the transmitted line pattern. The methods are backward compatible and optional. The first reason is to control the spectrum of the modulated signal to avoid certain optical interference phenomena. One method of partial control is presented. The second reason is to avoid the intentional disruption of the transmission link by a malicious user. Two methods of control are presented that achieve this. + +## I.1 Spectrum control using idle XGEM frames + +In the XG-PON system, the transmitter has the option of sending idle XGEM frames from time to time. In the conventional case, this happens when the transmitter does not have a user data packet ready to send. The size and content of the idle XGEM frame is entirely up to the transmitter to choose. This freedom provides the OLT with a measure of control over the spectrum of the signal transmitted in the downstream direction. + +The size of the idle packets is an arbitrary choice of implementation. However, to make the system efficient in both data transport and pattern control, it is advised that the size of the idle payload be in the range of 64 to 128 bytes. This will make the fraction of controlled line signal greater than 90% in the absence of real data, and it will occupy the line for no longer than 0.13 microseconds. + +The Port-ID used for the idle XGEM frames is given in clause 9.1.4. + +Clause I.1.1 describes the concept of the scrambler phase-dependent idle frame payload. This is substantially the same idea as presented in clause V.1.2 of [b-ITU-T G.984.3]. + +It should be noted that the scrambler in XG-PON has a very long repeat length, and as such it does not present source of short repeat length pattern. In fact, the fastest repeating structure one will likely see is the 8 kHz framing pattern. This frequency is low enough as to be negligible in the system. So, unlike G-PON, there would seem to be little use for a scrambler phase-independent payload. + +### I.1.1 Scrambler phase-dependent payload + +The scrambler phase-dependent payload pattern design is composed of two aspects. The first aspect is the design of the pattern that is desired to appear on the line. The desired pattern should be selected to have favourable spectral or temporal characteristics. One particular desired pattern is described below, but there are unlimited number of patterns that could be used. The second aspect is the management of the downstream scrambler. The scrambler will XOR with the idle XGEM frames, and thereby randomize the pattern on the line. To reverse this, the OLT must XOR the desired pattern with the scrambler pattern before the idle frames are scrambled. The OLT equipment must take care to use the scrambler pattern that is in exact bit alignment with the line scrambler. + +On the subject of selecting a desirable pattern, there are several characteristics of the line signal that can be of interest. One of these is the presence of repeating patterns that can produce frequency harmonics in the line signal. These harmonics can then leak into other signals (e.g., the video overlay) via stimulated Raman scattering (SRS), thereby causing crosstalk. Another characteristic is the overall spectrum of the line signal. Ordinary scrambled NRZ coding produces a spectrum that is given by the $\text{sinc}^2(f)$ function. This is weighted towards the low frequencies, as shown in Figure I.1. These low frequencies have enhanced non-linear fibre crosstalk associated with them. + +In view of these characteristics, a favourable desired pattern is one that has a very long repeat length, and that has a frequency spectrum that is shifted toward higher frequencies. A simple pattern with these properties is a pseudo-random Manchester coded sequence. The pseudo-random generator can + +be selected to have a primitive high-order polynomial (e.g., $2^{43}-1$ ), and is configured to operate at half the bit rate of the downstream signal. Then, each pseudo-random digit is encoded as a Manchester code symbol (01 or 10). The resulting pattern will have a spectrum, as shown in Figure I.1. + +It must be kept in mind that the idle pattern control is only effective for the fraction of time that the downstream XG-PON system is idle. To illustrate this, suppose that the system is operating at approximately 25% occupancy, and that the idle packet payloads are created to be 64 bytes long. In this case, the desired pattern appears on the line approximately 67% of the time. Therefore, the spectrum of the line signal will be the weighted average of the scrambled and Manchester coded spectra. The combined spectral intensity is shown in Figure I.1. In the important low frequency region (0.01 of the 10 Gbit/s bit rate), the reduction of spectral power density is around 4 dB in this example. This would produce a 3 dB improvement in Raman impairments for overlay signals on the PON. It should be noted that higher downstream utilization will produce less improvement, and vice versa. + +Another use of the scrambler phase-dependent idle payloads is to intentionally create line patterns with significant single frequency tones. These tones can be used to implement an optical frequency domain reflectometry (OFDR) system. In this concept, the transmitter is used as a delta-sigma modulator, and an arbitrary waveform can be generated by modulating the fractions of 0's and 1's sent in a certain period. As shown in Figure I.2, a very good generation of low frequency waveforms is possible. In this example, a sinusoidal function (the curve) is approximated by a sequence of 1's and 0's (the small dots). The accumulated error is shown by the dashed curve at the bottom. + +![Figure I.1: Spectra of NRZ, Manchester-coded, and combined patterns. The graph plots Spectral power density (Y-axis, 0 to 1.20) versus Frequency / Bit rate (X-axis, 0 to 1). Three curves are shown: NRZ (dashed purple line), Manchester (dashed orange line), and Combined (solid green line). The NRZ curve starts at 1.00 at 0 frequency and decreases. The Manchester curve starts at 0 at 0 frequency, peaks at approximately 1.05 at 0.4 frequency, and then decreases. The Combined curve starts at approximately 0.35 at 0 frequency, peaks at approximately 0.9 at 0.4 frequency, and then decreases, following the Manchester curve more closely than the NRZ curve at higher frequencies.](ed2c3e8ce1a7479b617b38a843c6b782_img.jpg) + +The figure is a line graph showing spectral power density on the y-axis (ranging from 0 to 1.20) against normalized frequency on the x-axis (ranging from 0 to 1). Three data series are plotted: a dashed purple line for NRZ, a dashed orange line for Manchester-coded, and a solid green line for the combined pattern. The NRZ curve starts at a spectral power density of 1.0 at 0 frequency and decreases monotonically. The Manchester-coded curve starts at 0 at 0 frequency, rises to a peak of about 1.05 at 0.4 frequency, and then decreases. The combined curve starts at approximately 0.35 at 0 frequency, rises to a peak of about 0.9 at 0.4 frequency, and then decreases, following the Manchester-coded curve more closely than the NRZ curve at higher frequencies. The label 'G.987.3(10)\_Fl.1' is present in the bottom right corner of the plot area. + +Figure I.1: Spectra of NRZ, Manchester-coded, and combined patterns. The graph plots Spectral power density (Y-axis, 0 to 1.20) versus Frequency / Bit rate (X-axis, 0 to 1). Three curves are shown: NRZ (dashed purple line), Manchester (dashed orange line), and Combined (solid green line). The NRZ curve starts at 1.00 at 0 frequency and decreases. The Manchester curve starts at 0 at 0 frequency, peaks at approximately 1.05 at 0.4 frequency, and then decreases. The Combined curve starts at approximately 0.35 at 0 frequency, peaks at approximately 0.9 at 0.4 frequency, and then decreases, following the Manchester curve more closely than the NRZ curve at higher frequencies. + +**Figure I.1 – Spectra of NRZ, Manchester-coded, and combined patterns** + +![Figure I.2: Synthesized waveform using idle payload control. The plot shows three data series over time (0 to 6.28). The 'Function' series is a smooth purple curve oscillating between approximately 0.0 and 1.0. The 'Bit pattern' series is a black line with dots, which is mostly flat at 1.0. The 'Error' series is a black line with squares, showing a noisy pattern between -1.0 and 0.0. The x-axis is labeled with values 0, 1.57, 3.14, 4.71, and 6.28. The y-axis has two scales: the left scale ranges from -1.0 to 1.0, and the right scale ranges from 1 to 3. The plot is labeled 'G.987.3(10)_FI.2'.](96feed67515fb3216a854d04a5d265a6_img.jpg) + +Figure I.2: Synthesized waveform using idle payload control. The plot shows three data series over time (0 to 6.28). The 'Function' series is a smooth purple curve oscillating between approximately 0.0 and 1.0. The 'Bit pattern' series is a black line with dots, which is mostly flat at 1.0. The 'Error' series is a black line with squares, showing a noisy pattern between -1.0 and 0.0. The x-axis is labeled with values 0, 1.57, 3.14, 4.71, and 6.28. The y-axis has two scales: the left scale ranges from -1.0 to 1.0, and the right scale ranges from 1 to 3. The plot is labeled 'G.987.3(10)\_FI.2'. + +**Figure I.2 – Synthesized waveform using idle payload control** + +## I.2 Intentional PON disruption + +A malicious user can attempt to intentionally disrupt the PON by downloading packets filled with the scrambler sequence. This could lead to excessive consecutive identical digits being transmitted, which will likely result in the ONU receivers losing synchronization. Losing synchronization would deny service to all the other legitimate users on the PON. + +The first line of defence against this attack in XG-PON is to use a scrambler with a larger polynomial, and to use a preload that is varied from frame to frame. This makes the odds of the attacker guessing the scrambler phase very small on each attempt, such that the mean time to success is measured in years. With such an unlikely payoff, such attacks are considered unattractive to the typical hacker. + +However, there is (in any scrambled system) the residual chance of intentional disruption. Clauses I.2.1 and I.2.2 discuss optional solutions to resolve this issue. + +### I.2.1 Data encryption + +One method of increasing the difficulty of PON disruption is to encrypt the user data. In this way, the user does not have the direct control over the data patterns being sent on the PON. This is especially true for the "casual hacker," who is only accessing the PON through the UNIs on the ONU, and therefore does not know the secret key being used on the PON. + +A sophisticated attacker may have access to the internal memory of his ONU, and therefore may know the encryption key. He could then arrange to modify the attack patterns so that when they are encrypted, they produce the scrambler pattern. Such a user would also likely know the scrambler phase as well, since we assume he or she has a direct observational knowledge of the PON. + +### I.2.2 Packet timing control + +An alternative method for the transmitter to prevent the malicious user from attacking the line pattern is to employ selective packet delay. In most work-conserving data systems, the transmitter sends the packets as they arrive. However, in the face of the kind of packet attack being considered, the transmitter can take precautions. If the transmitter pre-calculates the scrambled line pattern that would result from the immediate transmission of a packet, then it is able to identify any problematic result before it occurs. If the packet is found to produce unacceptable line patterns, then the transmitter can + +choose to insert an idle frame of any reasonable length (even an 8-byte header-only idle frame would work). This can shift the user's packet by many bits, and decorrelate its payload from the scrambler's phase. + +This approach is particularly useful in thwarting the would-be attacker because the attacker would not even know that his attack has been detected and defeated. It also has the property that the XG-PON protocols are not modified. This method can also be used to reduce accidental excursions of the line pattern that are due to just random data, subject to limitations on how much deviation from work-conserving scheduling is permitted. + +# Appendix II + +## Time of day derivation and error analysis + +(This appendix does not form an integral part of this Recommendation.) + +This appendix provides the mathematical details for the time of day transfer model derivation and error analysis. It is based on the notation of clause 13.2.1. In addition, + +$T_{1270}$ is the upstream propagation delay at the 1270 nm wavelength, and + +$T_{1577}$ is the downstream propagation delay at the 1577 nm wavelength. + +By construction (see Figures 13-4 and 13-7 with accompanying text), the upstream PHY frame offset can be represented using the parameters of ONU $i$ as: + +$$\begin{aligned} Teqd &= T_{1577,i} + RspTime_i + EqD_i + T_{1270,i} \\ &= T_{1577,i} \frac{n_{1270} + n_{1577}}{n_{1577}} + RspTime_i + EqD_i \end{aligned} \quad (II-1)$$ + +Then by expressing $T_{1577,i}$ from Equation (II-1) as: + +$$T_{1577,i} = (Teqd - RspTime_i - EqD_i) \frac{n_{1577}}{n_{1270} + n_{1577}} \quad (II-2)$$ + +and substituting this expression into the formula for the receive instance of XGTC frame $N$ , + +$$Trecv_{N,i} = Tsend_{N,i} + T_{1577,i} \quad (II-3)$$ + +and regrouping appropriately, we can obtain the representation of the actual ToD instance when XGTC frame $N$ is delivered to ONU $i$ : + +$$Trecv_{N,i} = Tsend_{N,i} + Teqd \left[ \frac{n_{1577}}{n_{1270} + n_{1577}} \right]_{OLT} - (EqD_i + RspTime_i) \left[ \frac{n_{1577}}{n_{1270} + n_{1577}} \right]_{ONU} \quad (II-4)$$ + +where the positive additive term can be computed by the OLT and communicated downstream, while the negative additive term can be computed by the ONU. + +Note that for the model to hold, the measurements of $Teqd$ , $Tsend_{N,i}$ , and $Trecv_{N,i}$ should be consistently referenced to the fibre interface at the OLT and ONU, respectively. + +Note further that, in addition to the ONU response time shown here, there are also internal delays that need to be compensated in both the OLT and ONU. These internal delay compensations directly affect the delivered time accuracy, so the resultant error is quite easy to understand. These errors are not considered further in this treatment. + +It should be noted that the refractive index factors are used in calculations on both sides of the PON, and their values could differ depending on the implementation. To eliminate the error caused by inconsistent values, it is recommended that both sides use the common value estimated below. + +The resulting timing error caused by variations in the index factor is then given by: + +$$Error_{N,i} = Teqd \delta \left[ \frac{n_{1577}}{n_{1270} + n_{1577}} \right]_{OLT} - (EqD_i + RspTime_i) \delta \left[ \frac{n_{1577}}{n_{1270} + n_{1577}} \right]_{ONU} \quad (II-5)$$ + +Here $\delta$ is an error of the refractive index estimate evaluated at the particular network element. + +This equation indicates that the error due to the OLT's refractive index factor variation is fixed (over all ONUs), and it is indeed at the maximum value of $Teqd$ , which is typically 250 microseconds. + +The error due to the ONU's index factor variation depends on the EqD and the response time of that ONU; therefore, nearby ONUs will have a larger error caused by inaccuracies in the ONU's index factor (a rather counter-intuitive result). It should be noted, however, that these errors may cancel out to some degree. To assure this cancelation, it is recommended that the calculation use the common value estimated below. + +Looking deeper into the index factor, denoting the group refractive index at 1577 nm with $n$ , and the difference between group indices at 1270 and 1577 nm with $\Delta n$ ; rewriting: + +$$\frac{n_{1577}}{n_{1270} + n_{1577}} = \frac{n_{1577}}{2n_{1577} + (n_{1270} - n_{1577})} = \frac{n}{2n + \Delta n} \approx \frac{2n^2 - n\Delta n}{4n^2} = \frac{1}{2} - \frac{\Delta n}{4n} \quad (\text{II-6})$$ + +Considering the effect of variations of $n$ and $\Delta n$ by taking partial derivatives with respect to these variables. It can be seen that: + +$$\frac{\partial}{\partial n} \left( \frac{1}{2} - \frac{\Delta n}{4n} \right) = + \frac{\Delta n}{4n^2} \text{ and } \frac{\partial}{\partial \Delta n} \left( \frac{1}{2} - \frac{\Delta n}{4n} \right) = - \frac{1}{4n} \quad (\text{II-7})$$ + +It is important to note that $n$ is about 3 orders of magnitude larger than $\Delta n$ . Therefore, the first expression is very much smaller than the second one, and can be neglected. The second expression states that small changes in $\Delta n$ will be translated into small changes of the index factor in the proportion $1/4n$ . + +So, we must calculate $\Delta n$ (the "index difference"), and then consider its variations. + +### Calculation of the index difference + +The wavelength-dependent difference in refractive index $\Delta n$ depends on the fibre properties and on the actual wavelengths that are involved (as real PON transmitters may operate over a range of wavelengths). An accurate representation of the index of ITU-T G.652 fibre is difficult to obtain. Typical spot values for the index at 1310 and 1550 nm are available, but these do not have the accuracy that is needed. The dispersion of fibres is given for certain windows (e.g., the 1310 window), but these formulations are not accurate when extrapolated beyond their window. Nevertheless, proceeding with the standardized dispersion factor, suffers the potential inaccuracy that such a generalization imposes. If a better function can be determined, then the analysis can be applied to that. + +The dispersion of ITU-T G.652 fibre is given by: + +$$D(\lambda) = \frac{\lambda S_0}{4} \left[ 1 - \frac{\lambda_0^4}{\lambda^4} \right] \quad (\text{II-8})$$ + +where $S_0$ is the dispersion slope (maximum 0.092 ps/nm2/km), and $\lambda_0$ is the zero dispersion wavelength (ranging from 1300 to 1324 nm). + +The index of refraction and $D$ are related by $\frac{dn}{d\lambda} = cD(\lambda)$ , and the fundamental theorem of calculus shows us that: + +$$n = n_0 + c \int_{\lambda_0}^{\lambda} D(\lambda) d\lambda \quad (\text{II-9})$$ + +Integrating, it can be found that: + +$$n - n_0 = \frac{cS_0}{8} \lambda^2 \left[ 1 - \frac{\lambda_0^2}{\lambda^2} \right]^2 \quad (\text{II-10})$$ + +The index difference function is graphed for the two extreme cases of ITU-T G.652 fibre in Figure II.1, where the zero dispersion wavelengths are 1300 and 1324 nm. Also shown are the wavelength ranges for the "reduced" type XG-PON transmitters (1260 to 1280 nm for the upstream and 1575 to 1580 nm for the downstream). The maximum index difference is 0.000893, and the minimum index difference is 0.000676. + +![Figure II.1: A line graph showing the refractive index difference as a function of operating wavelength. The y-axis is labeled 'x10^-3' and ranges from 0 to 1.2. The x-axis ranges from 1200 to 1600 nm. Two curves are plotted: a blue curve (representing the 1300 nm zero dispersion wavelength case) and a red curve (representing the 1324 nm zero dispersion wavelength case). Both curves show a minimum index difference near 1300 nm. The blue curve is slightly higher than the red curve at 1200 nm and 1600 nm. The graph is labeled 'G.987.3(10)_FII.1' at the bottom right.](39dfa32741836e2dffe40299334e9c74_img.jpg) + +Figure II.1: A line graph showing the refractive index difference as a function of operating wavelength. The y-axis is labeled 'x10^-3' and ranges from 0 to 1.2. The x-axis ranges from 1200 to 1600 nm. Two curves are plotted: a blue curve (representing the 1300 nm zero dispersion wavelength case) and a red curve (representing the 1324 nm zero dispersion wavelength case). Both curves show a minimum index difference near 1300 nm. The blue curve is slightly higher than the red curve at 1200 nm and 1600 nm. The graph is labeled 'G.987.3(10)\_FII.1' at the bottom right. + +**Figure II.1 – Refractive index difference as a function of operating wavelength** + +In practical systems, operating wavelengths are not monitored, nor is the exact fibre dispersion known. Hence, the index difference is truly an unknown quantity. Qualitatively, the variation of the 1260 transmitter has little effect, because it is close to the minimum of the curve. Interestingly, variation of the fibre dispersion zero wavelength and variation of the 1577 nm transmitter wavelength have nearly equal effect in modifying the index difference. + +## Index factor variability + +Using Equation (II-6) and substituting the value $n = 1.47$ , which is a valid approximation for the group refractive indices of the commonly deployed fibres (precision is not important here), it is found that the index factor can range from 0.500115 to 0.500153. The most plausible refractive index factor value is 0.500134, but this may be incorrect by an amount of up to $\pm 0.000019$ . The most accurate solution is achieved when both the OLT and ONU use these common values: + +$$\frac{n_{1577}}{n_{1270} + n_{1577}} \approx 0.500134$$ + +$$\delta \left[ \frac{n_{1577}}{n_{1270} + n_{1577}} \right] \leq 0.000019$$ + +eliminating the error due to differing values on either side of the PON. The inaccuracy of the time then amounts to $\pm 0.000019$ times the round trip time of the fibre. For an ONU at 20 km, the round trip time is approximately 200 microseconds and, therefore, the inaccuracy is $\pm 3.8$ ns and is negligible. + +# Appendix III + +## Burst profiles + +(This appendix does not form an integral part of this Recommendation.) + +This appendix describes burst profiles to be used by the PHY adaptation sublayer of the ONU to form the PHY burst. Suggested values of burst preamble and delimiter are presented. + +In the XG-PON system, upstream transmission from ONUs to the OLT is conducted by delivering a number of PHY bursts. After a 64-bit guard time for burst overlap prevention, the PHY burst starts with the upstream physical synchronization block (PSBu) section. The PSBu contains preamble and delimiter. Preamble and delimiter are employed by the OLT burst mode receiver to determine the presence of a PHY burst and delineate the PHY burst. They are also used to determine the signal clock in order to correctly recover the transmitted signal. + +The length and pattern of preamble and delimiter are formed as dictated by the OLT in the BurstProfile field in the BWmap. The index in the BurstProfile field refers to the set of valid burst profiles that is communicated to the ONUs over the PLOAM messaging channel. For each specified profile, the index is explicitly defined in the Profile PLOAM message. + +The Profile PLOAM message can be broadcast or unicast. It is up to the OLT to manage the burst profiles, and to anticipate which ONUs will have which profiles. The ONU is purely a slave in this situation, and will follow the instructions that the OLT gives to it. In the simplest case, the OLT can send only broadcast profile messages. The profiles then obtain global scope, and are equal on all ONUs. In a more complex case, the OLT can send unicast profiles to each ONU. These unicast profiles could then be different for each ONU (again, it is incumbent on the OLT to keep track of what it has configured in each ONU). Regarding temporal behaviour, the OLT should always send the profile message several times before it attempts to use them in a BWmap. In this way, the probability of the ONU using an old profile will be greatly reduced. + +The recommended size of preamble is 160 bits [ITU-T G.987.2]. Preambles with varying sizes can be achieved by setting the burst profile to the desired parameters. + +A traditional preamble pattern is 0x AAAA AAAA. While it provides maximum transition density and averaged power, some implementations may have different preamble requirements. For example, if the burst mode receiver has bandwidth limited front ends, the aforementioned preamble pattern is not able to support highly efficient burst presence detection. Another example is burst mode receivers with peak detectors. If the peak detectors have limited slew rates in the sample and hold circuit, the aforementioned preamble cannot fulfil highly efficient burst presence detection. Therefore, data-like preamble patterns are added into the possible preamble patterns. The selected data-like preamble patterns are expected to have features of DC-balance, flat power spectrum, transition density similar to that of random data, and long run length. The suggested values of XG-PON preamble patterns are shown in Table III.1. + +The recommended size of delimiter is 32 bits. When a longer delimiter time is required in the case of high BER, 64-bits delimiters can be used to provide more robust burst delineation. The expected features of the selected delimiters include balanced 1's and 0's, large distance from all shifted patterns of itself, and large distance from all shifted patterns of the preamble. + +In other cases, it is desirable to indicate if the burst has FEC active or not using a pair of distinct delimiters. The suggested values of such pairs of delimiters are shown in Table III.1. + +**Table III.1 – Suggested values of preamble and delimiter** + +| Preamble | 32-bit delimiter | 64-bit delimiter | +|-----------------|-------------------------|----------------------------------| +| 0x BB52 1E26 | 0x A376 70C9 | 0x B9D4 3E68 462B C197 | +| | 0x 4BDE 1B90 (FEC on) | 0x B9D4 3E68 462B C197 (FEC on) | +| | 0x A376 70C9 (FEC off) | 0x B752 1F06 48AD E879 (FEC off) | +| 0x AAAA AAAA | 0x AD4C C30F | 0x B3BD D310 B2C5 0FA1 | +| | 0x A566 79E0 (FEC on) | 0x B3BD D310 B2C5 0FA1 (FEC on) | +| | 0x AD4C C30F (FEC off) | 0x CE99 CE5E 5028 B41F (FEC off) | + +# Appendix IV + +## Golden vectors + +(This appendix does not form an integral part of this Recommendation.) + +## IV.1 Downstream FEC codeword + +This is an example of a downstream FEC codeword. The payload is an incrementing string of bytes starting at 0x01 and having the length of 216. The 32 FEC parity bytes are shown underlined. + +RS(248, 216) + +0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f 0x10 +0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f 0x20 +0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f 0x30 +0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f 0x40 +0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49 0x4a 0x4b 0x4c 0x4d 0x4e 0x4f 0x50 +0x51 0x52 0x53 0x54 0x55 0x56 0x57 0x58 0x59 0x5a 0x5b 0x5c 0x5d 0x5e 0x5f 0x60 +0x61 0x62 0x63 0x64 0x65 0x66 0x67 0x68 0x69 0x6a 0x6b 0x6c 0x6d 0x6e 0x6f 0x70 +0x71 0x72 0x73 0x74 0x75 0x76 0x77 0x78 0x79 0x7a 0x7b 0x7c 0x7d 0x7e 0x7f 0x80 +0x81 0x82 0x83 0x84 0x85 0x86 0x87 0x88 0x89 0x8a 0x8b 0x8c 0x8d 0x8e 0x8f 0x90 +0x91 0x92 0x93 0x94 0x95 0x96 0x97 0x98 0x99 0x9a 0x9b 0x9c 0x9d 0x9e 0x9f 0xa0 +0xa1 0xa2 0xa3 0xa4 0xa5 0xa6 0xa7 0xa8 0xa9 0xaa 0xab 0xac 0xad 0xae 0xaf 0xb0 +0xb1 0xb2 0xb3 0xb4 0xb5 0xb6 0xb7 0xb8 0xb9 0xba 0xbb 0xbc 0xbd 0xbe 0xbf 0xc0 +0xc1 0xc2 0xc3 0xc4 0xc5 0xc6 0xc7 0xc8 0xc9 0xca 0xcb 0xcc 0xcd 0xce 0xcf 0xd0 +0xd1 0xd2 0xd3 0xd4 0xd5 0xd6 0xd7 0xd8 0x6d 0x8d 0x89 0x21 0x88 0x4d 0x6b 0x21 +0x2e 0x3c 0xd6 0x8e 0x68 0x54 0x72 0x31 0x52 0xbd 0x9e 0xf7 0x45 0xf5 0x70 0x20 +0x60 0xc4 0xe2 0xec 0x0b 0xef 0x18 0x1a + +## IV.2 Upstream FEC codeword + +This is an example of an upstream FEC codeword. The payload is an incrementing string of bytes starting at 0x01 and having the length of 232. The 16 bytes of FEC parity are shown underlined. + +RS(248, 232) + +0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f 0x10 +0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f 0x20 +0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f 0x30 +0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f 0x40 +0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49 0x4a 0x4b 0x4c 0x4d 0x4e 0x4f 0x50 +0x51 0x52 0x53 0x54 0x55 0x56 0x57 0x58 0x59 0x5a 0x5b 0x5c 0x5d 0x5e 0x5f 0x60 +0x61 0x62 0x63 0x64 0x65 0x66 0x67 0x68 0x69 0x6a 0x6b 0x6c 0x6d 0x6e 0x6f 0x70 +0x71 0x72 0x73 0x74 0x75 0x76 0x77 0x78 0x79 0x7a 0x7b 0x7c 0x7d 0x7e 0x7f 0x80 +0x81 0x82 0x83 0x84 0x85 0x86 0x87 0x88 0x89 0x8a 0x8b 0x8c 0x8d 0x8e 0x8f 0x90 +0x91 0x92 0x93 0x94 0x95 0x96 0x97 0x98 0x99 0x9a 0x9b 0x9c 0x9d 0x9e 0x9f 0xa0 +0xa1 0xa2 0xa3 0xa4 0xa5 0xa6 0xa7 0xa8 0xa9 0xaa 0xab 0xac 0xad 0xae 0xaf 0xb0 +0xb1 0xb2 0xb3 0xb4 0xb5 0xb6 0xb7 0xb8 0xb9 0xba 0xbb 0xbc 0xbd 0xbe 0xbf 0xc0 + +``` + +0xc1 0xc2 0xc3 0xc4 0xc5 0xc6 0xc7 0xc8 0xc9 0xca 0xcb 0xcc 0xcd 0xce 0xcf 0xd0 +0xd1 0xd2 0xd3 0xd4 0xd5 0xd6 0xd7 0xd8 0xd9 0xda 0xdb 0xdc 0xdd 0xde 0xdf 0xe0 +0xe1 0xe2 0xe3 0xe4 0xe5 0xe6 0xe7 0xe8 0x41 0x42 0xda 0xe0 0x73 0x7c 0x7b 0x52 +0xb8 0x27 0xe4 0xb8 0x4e 0x2b 0xee 0xbf + +``` + +## IV.3 Upstream FEC short codeword + +This is an example of a short upstream FEC codeword. The payload is an incrementing string of bytes starting at 0x01 and having the length of 204. The 16 bytes of FEC parity are shown underlined. + +RS(220, 204) + +``` + +0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f 0x10 +0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f 0x20 +0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f 0x30 +0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f 0x40 +0x41 0x42 0x43 0x44 0x45 0x46 0x47 0x48 0x49 0x4a 0x4b 0x4c 0x4d 0x4e 0x4f 0x50 +0x51 0x52 0x53 0x54 0x55 0x56 0x57 0x58 0x59 0x5a 0x5b 0x5c 0x5d 0x5e 0x5f 0x60 +0x61 0x62 0x63 0x64 0x65 0x66 0x67 0x68 0x69 0x6a 0x6b 0x6c 0x6d 0x6e 0x6f 0x70 +0x71 0x72 0x73 0x74 0x75 0x76 0x77 0x78 0x79 0x7a 0x7b 0x7c 0x7d 0x7e 0x7f 0x80 +0x81 0x82 0x83 0x84 0x85 0x86 0x87 0x88 0x89 0x8a 0x8b 0x8c 0x8d 0x8e 0x8f 0x90 +0x91 0x92 0x93 0x94 0x95 0x96 0x97 0x98 0x99 0x9a 0x9b 0x9c 0x9d 0x9e 0x9f 0xa0 +0xa1 0xa2 0xa3 0xa4 0xa5 0xa6 0xa7 0xa8 0xa9 0xaa 0xab 0xac 0xad 0xae 0xaf 0xb0 +0xb1 0xb2 0xb3 0xb4 0xb5 0xb6 0xb7 0xb8 0xb9 0xba 0xbb 0xbc 0xbd 0xbe 0xbf 0xc0 +0xc1 0xc2 0xc3 0xc4 0xc5 0xc6 0xc7 0xc8 0xc9 0xca 0xcb 0xcc 0x1e 0xe8 0xd8 0xc6 +0xca 0x13 0xf9 0xed 0x3b 0xb3 0x53 0xe7 0x04 0x51 0x13 0x93 + +``` + +## IV.4 Downstream AES-128 encryption + +``` + +Data encryption key: 0x112233445566778899AABBCCDDEEFF00 +Superframe counter: 0x0001028385834 +Intraframe counter: 0x0078 + +``` + +Plaintext + +``` + +0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f +0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f +0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f +0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f + +``` + +Counter blocks + +``` + +0x00040a0e160d007800040a0e160d0078 +0x00040a0e160d007800040a0e160d0079 +0x00040a0e160d007800040a0e160d007a +0x00040a0e160d007800040a0e160d007b + +``` + +Ciphertext + +``` + +0xff 0xd1 0xae 0x0c 0x4b 0x46 0xc9 0xc1 0x29 0x2f 0xde 0x06 0x1b 0x18 0xef 0x9c +0x87 0xb5 0x65 0x61 0x76 0xff 0x1c 0x6e 0xb2 0xf0 0xda 0xcd 0x53 0x8d 0x4a 0xd0 +0x5b 0x38 0x9b 0xff 0xee 0x94 0x7b 0x54 0xcf 0xf7 0x74 0x54 0xd4 0x2d 0x08 0xfa + +``` + +0x20 0x30 0x96 0x50 0xa4 0x3b 0xc1 0x40 0xc6 0x73 0xb0 0xf4 0x6e 0xcd 0x5b 0xeb + +## IV.5 Upstream AES-128 encryption + +Data encryption key: 0x112233445566778899AABBCCDDEEFF00 + +Superframe counter: 0x0001028385834 + +Intraframe counter: 0x097c + +### Plaintext + +0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f +0x10 0x11 0x12 0x13 0x14 0x15 0x16 0x17 0x18 0x19 0x1a 0x1b 0x1c 0x1d 0x1e 0x1f +0x20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 0x28 0x29 0x2a 0x2b 0x2c 0x2d 0x2e 0x2f +0x30 0x31 0x32 0x33 0x34 0x35 0x36 0x37 0x38 0x39 0x3a 0x3b 0x3c 0x3d 0x3e 0x3f + +### Counter blocks + +0x00040a0e160d097cfffbf5f1e9f2f683 + +0x00040a0e160d097cfffbf5f1e9f2f684 + +0x00040a0e160d097cfffbf5f1e9f2f685 + +0x00040a0e160d097cfffbf5f1e9f2f686 + +### CipherText + +0x0d 0x5a 0x46 0x57 0xfd 0x68 0x6f 0xa4 0xb3 0x8f 0x77 0x3a 0x88 0x7a 0x2b 0x33 +0x86 0xd7 0xfe 0x53 0x3c 0x52 0x24 0xab 0x39 0x61 0xae 0x20 0xe6 0x15 0x12 0x0e +0xbb 0x2f 0xec 0xe4 0x16 0x50 0x5a 0x02 0x73 0x68 0x39 0x59 0x73 0x8b 0xd6 0x7d +0x75 0x96 0x85 0xcd 0x62 0x14 0x69 0xc1 0x14 0x66 0x59 0xf1 0xc3 0xa7 0xe4 0xd8 + +## IV.6 Key derivation encryption + +MSK-128 = 0x112233445566778899AABBCCDDEEFF00 + +PON-TAG = 0x4f4c542344556677 + +ONU SN = 0x564e445200112233 + +SK = 0x795fcf6cb215224087430600dd170f07 + +OMCI\_IK = 0x184b8ad4d1ac4af4dd4b339ecc0d3370 + +PLOAM\_IK = 0xe256ce76785c78717c7b3044ab28e2cd + +KEK = 0x6f9c99b8361768937e453b165f609710 + +## IV.7 Downstream PLOAM message integrity check + +PLOAM message parameters: + +Message Type: Assign\_Alloc-ID + +ONU-ID = 0x13 + +SeqNo = 0x03 + +Alloc-ID value = 0x0445 + +Alloc-ID type = 0x01 (XGEM) + +PLOAM\_IK = 0xe256ce76785c78717c7b3044ab28e2cd + +**AES-CMAC-64( PLOAM\_IK, 0x01|MSG)** + +0x46 0x39 0x87 0x56 0x28 0x08 0x14 0xe6 + +## IV.8 Upstream PLOAM message integrity check + +PLOAM message parameters: + +Message Type: Sleep\_Request + +ONU-ID = 0x13 + +SeqNo = 0x00 + +Activity\_level = 0x02 + +PLOAM\_IK = 0xe256ce76785c78717c7b3044ab28e2cd + +**AES-CMAC-64( PLOAM\_IK, 0x02|MSG)** + +0x68 0xae 0x4d 0xd7 0x75 0x55 0x0a 0xcb + +## IV.9 Upstream key reporting + +Data\_encryption\_key = 0x112233445566778899AABBCCDDEEFF00 + +KEK = 0x6f9c99b8361768937e453b165f609710 + +**AES-ECB (KEK, Data\_encryption\_key)** + +0x4018340d538bb3f50df3186cf075f7b6 + +**AES-CMAC (KEK, Data\_encryption\_key | 0x33313431353932363533353839373933, 128)** + +0x3cc507bb1731c569ed7b79f8bdc376be + +## IV.10 Downstream OMCI message integrity check + +OMCI message direction: + +Cdir = 0x01 (downstream) + +OMCI\_CONTENT: + +Transaction correlation identifier: 0x80 0x00 + +Message type: 0x49 (GET) + +Device identifier: 0x0A (Baseline OMCI) + +Managed entity identifier: 0x01 0x00 0x00 0x00 (ONU-G) + +Message contents: + +0x00 0x80 0x00 0x00 0x00 0x00 0x00 0x00 + +0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 + +0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 + +0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 + +OMCI trailer[1:4]: 0x00 0x00 0x00 0x28 + +OMCI\_IK = 0x184b8ad4dlac4af4dd4b339ecc0d3370 + +**AES-CMAC (OMCI\_IK, (Cdir | OMCI\_CONTENT) , 32)** + +0x78dca53d + +# Bibliography + +- [b-ITU-T G.671] Recommendation ITU-T G.671 (2025), *Transmission characteristics of optical components and subsystems.* +- [b-ITU-T G.841] Recommendation ITU-T G.841 (1998), *Types and characteristics of SDH network protection architectures.* +- [b-ITU-T G.984.2] Recommendation ITU-T G.984.2 (2019), *Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification.* +- [b-ITU-T G.984.3] Recommendation ITU-T G.984.3 (2014), *Gigabit-capable passive optical networks (G-PON): Transmission convergence layer specification.* +- [b-ITU-T G Suppl.81] ITU-T G-series Recommendations – Supplement 81 (2024), *Practical aspects of PON security.* +- [b-ITU-T G Suppl.84] ITU-T G-series Recommendations – Supplement 84 (2025), *Operational aspects of optical access.* +- [b-SFF SFF8472] SFF-8472 Rev. 11.3 (2013), *Specification for Diagnostic Monitoring Interface for Optical Transceivers.* + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| 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It features the letters "ITU" in a bold, blue, sans-serif font, superimposed on a stylized globe icon with intersecting lines. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.988 + +# ONU management and control interface (OMCI) specification + +## Summary + +Recommendation ITU-T G.988 specifies the optical network unit (ONU) management and control interface (OMCI) for optical access networks. + +Recommendation ITU-T G.988 specifies the managed entities (MEs) of a protocol-independent management information base (MIB) that models the exchange of information between an optical line termination (OLT) and an ONU. In addition, it covers the ONU management and control channel, protocol and detailed messages. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|---------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.988 | 2010-10-07 | 15 | 11.1002/1000/10891 | +| 1.1 | ITU-T G.988 (2010) Amd. 1 | 2011-04-13 | 15 | 11.1002/1000/11126 | +| 1.2 | ITU-T G.988 (2010) Amd. 2 | 2012-04-22 | 15 | 11.1002/1000/11501 | +| 1.3 | ITU-T G.988 (2010) Cor. 1 | 2012-06-13 | 15 | 11.1002/1000/11641 | +| 2.0 | ITU-T G.988 | 2012-10-29 | 15 | 11.1002/1000/11784 | +| 2.1 | ITU-T G.988 (2012) Amd. 1 | 2014-05-14 | 15 | 11.1002/1000/12185 | +| 2.2 | ITU-T G.988 (2012) Amd. 2 | 2016-06-22 | 15 | 11.1002/1000/12795 | +| 3.0 | ITU-T G.988 | 2017-11-06 | 15 | 11.1002/1000/13291 | +| 3.1 | ITU-T G.988 (2017) Amd. 1 | 2018-11-29 | 15 | 11.1002/1000/13744 | +| 3.2 | ITU-T G.988 (2017) Amd. 2 | 2019-08-29 | 15 | 11.1002/1000/14001 | +| 3.3 | ITU-T G.988 (2017) Amd. 3 | 2020-03-15 | 15 | 11.1002/1000/14192 | +| 3.4 | ITU-T G.988 (2017) Amd. 4 | 2021-09-06 | 15 | 11.1002/1000/14623 | +| 3.5 | ITU-T G.988 (2017) Amd. 5 | 2022-06-06 | 15 | 11.1002/1000/14886 | +| 4.0 | ITU-T G.988 | 2022-11-13 | 15 | 11.1002/1000/15125 | + +## Keywords + +E-PON, G-PON, HS-PON, NG-PON2, OMCI, PON, XG-PON, XGS-PON. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2023 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|--------------------------------------------------------------|-----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 6 | +| 3.1 | Terms defined elsewhere ..... | 6 | +| 3.2 | Terms defined in this Recommendation ..... | 6 | +| 4 | Abbreviations and acronyms ..... | 6 | +| 5 | Conventions ..... | 15 | +| 6 | Reference model and terms ..... | 15 | +| 6.1 | OMCI in the access network..... | 15 | +| 6.2 | ONU functions..... | 16 | +| 6.3 | Support of multicast connection..... | 16 | +| 6.4 | Voice over Internet protocol management..... | 16 | +| 7 | Requirements of the management interface specification ..... | 17 | +| 7.1 | Configuration management..... | 18 | +| 7.2 | Fault management ..... | 18 | +| 7.3 | Performance management..... | 19 | +| 7.4 | Security management ..... | 19 | +| 8 | Protocol-independent MIB for the OMCI ..... | 19 | +| 8.1 | Managed entities..... | 19 | +| 8.2 | Managed entity relation diagrams ..... | 30 | +| 9 | MIB description..... | 54 | +| 9.1 | Equipment management..... | 57 | +| 9.2 | ANI management, traffic management ..... | 101 | +| 9.3 | Layer 2 data services ..... | 138 | +| 9.4 | Layer 3 data services..... | 219 | +| 9.5 | Ethernet services..... | 230 | +| 9.6 | This clause is intentionally left blank..... | 243 | +| 9.7 | xDSL services ..... | 243 | +| 9.8 | Time division multiplex services..... | 355 | +| 9.9 | Voice services..... | 383 | +| 9.10 | Premises networks..... | 418 | +| 9.11 | This clause is intentionally left blank..... | 424 | +| 9.12 | General purpose managed entities..... | 424 | +| 9.13 | Miscellaneous services..... | 451 | +| 9.14 | Mid-span passive optical network reach extender..... | 468 | +| 9.15 | RS232/RS485 interface service ..... | 483 | +| 9.16 | ITU-T G.989.3 TWDM and ITU-T G.9804.2 TWDM/TDM PON ..... | 486 | + +| | Page | | +|--------------------|---------------------------------------------------------------------------------|-----| +| 10 | This clause is intentionally left blank..... | 502 | +| 11 | ONU management and control protocol ..... | 502 | +| 11.1 | Baseline and extended messages ..... | 502 | +| 11.2 | Common message characteristics..... | 504 | +| Annex A – | OMCI message syntax and common features ..... | 520 | +| A.1 | General ..... | 520 | +| A.2 | Extended message set..... | 529 | +| A.3 | Baseline message set ..... | 571 | +| Annex B – | OMCI in ITU-T PON systems ..... | 613 | +| B.1 | Establishing the ONU management and control channel (OMCC) ..... | 613 | +| B.2 | OMCI handling within the ONU ..... | 614 | +| Annex C – | OMCI in Ethernet PON systems ..... | 619 | +| C.1 | Establishing the ONU management and control channel (OMCC) ..... | 619 | +| C.2 | Encapsulating OMCI messages in Ethernet frames ..... | 620 | +| C.3 | Relationship between the OMCI and OAM defined in clause 57 of [IEEE 802.3]..... | 621 | +| C.4 | Adaptation of the G-PON information model to EPON ..... | 621 | +| Appendix I – | OMCI common services..... | 626 | +| I.1 | ONU MIB management..... | 626 | +| I.2 | Equipment management..... | 633 | +| I.3 | Software upgrade..... | 644 | +| I.4 | Performance monitoring ..... | 651 | +| Appendix II – | G-PON mechanisms and services..... | 657 | +| II.1 | Layer 2 data service according to [b-BBF TR-156]..... | 657 | +| II.2 | Dual-managed ONUs ..... | 669 | +| II.3 | Traffic management ..... | 671 | +| II.4 | Voice services..... | 686 | +| II.5 | Extended layer 2 data service model..... | 692 | +| Appendix III – | This appendix is intentionally left blank ..... | 695 | +| Bibliography ..... | | 696 | + +# Recommendation ITU-T G.988 + +# ONU management and control interface (OMCI) specification + +# 1 Scope + +This Recommendation specifies the optical network unit (ONU) management and control interface (OMCI) for optical access networks. + +The OMCI specification addresses ONU configuration, fault management and performance management for optical access system operation, and for several services including: + +- gigabit-capable passive optical network encapsulation method (GEM) adaptation layers; +- Ethernet services, including media access control (MAC) bridged local area networks (LANs); +- circuit emulation service (CES); +- voice services. + +This Recommendation defines a protocol necessary to support the capabilities identified for these ONUs. It also allows optional components and future extensions. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T E.164] Recommendation ITU-T E.164 (2005), *The international public telecommunication numbering plan.* +- [ITU-T G.704] Recommendation ITU-T G.704 (1998), *Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels.* +- [ITU-T G.722.1] Recommendation ITU-T G.722.1 (2005), *Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss.* +- [ITU-T G.722.2] Recommendation ITU-T G.722.2 (2003), *Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB).* +- [ITU-T G.723.1] Recommendation ITU-T G.723.1 (2006), *Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s.* +- [ITU-T G.728] Recommendation ITU-T G.728 (1992), *Coding of speech at 16 kbit/s using low-delay code excited linear prediction.* +- [ITU-T G.729] Recommendation ITU-T G.729 (2007), *Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP).* +- [ITU-T G.784] Recommendation ITU-T G.784 (2008), *Management aspects of synchronous digital hierarchy (SDH) transport network elements.* +- [ITU-T G.826] Recommendation ITU-T G.826 (2002), *End-to-end error performance parameters and objectives for international, constant bit-rate digital paths and connections.* + +- [ITU-T G.983.2] Recommendation ITU-T G.983.2 (2005), *ONT management and control interface specification for B-PON*. +- [ITU-T G.984.x] Recommendation ITU-T G.984.x-series, *Gigabit-capable passive optical networks (G-PON)*. +- [ITU-T G.984.3] Recommendation ITU-T G.984.3 (2008), *Gigabit-capable passive optical networks (G-PON): Transmission convergence layer specification*. +- [ITU-T G.984.4] Recommendation ITU-T G.984.4 (2008), *Gigabit-capable passive optical networks (G-PON): ONT management and control interface specification*. +- [ITU-T G.984.6] Recommendation ITU-T G.984.6 (2008), *Gigabit-capable passive optical networks (GPON): Reach extension*. +- [ITU-T G.986] Recommendation ITU-T G.986 (2010), *1 Gbit/s point-to-point Ethernet-based optical access system*. +- [ITU-T G.987.x] ITU-T G.987.x-series of Recommendations, *10 Gigabit-capable passive optical network (XG-PON) systems*. +- [ITU-T G.987] Recommendation ITU-T G.987 (10/2010), *10-Gigabit-capable passive optical network (XG-PON) systems: Definitions, abbreviations, and acronyms*. +- [ITU-T G.987.1] Recommendation ITU-T G.987.1 (2010), *10-Gigabit-capable passive optical networks (XG-PON): General requirements*. +- [ITU-T G.987.3] Recommendation ITU-T G.987.3 (2010), *10-Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification*. +- [ITU-T G.989.3] Recommendation ITU-T G.989.3 (2015), *40-Gigabit-capable passive optical networks (NG-PON2): Transmission convergence layer specification*. +- [ITU-T G.992.x] ITU-T G.992.x series of Recommendations. +- [ITU-T G.992.1] Recommendation ITU-T G.992.1 (1999), *Asymmetric digital subscriber line (ADSL) transceivers*. +- [ITU-T G.992.2] Recommendation ITU-T G.992.2 (1999), *Splitterless asymmetric digital subscriber line (ADSL) transceivers*. +- [ITU-T G.992.3] Recommendation ITU-T G.992.3 (2009), *Asymmetric digital subscriber line transceivers 2 (ADSL2)*. +- [ITU-T G.992.4] Recommendation ITU-T G.992.4 (2002), *Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2)*. +- [ITU-T G.992.5] Recommendation ITU-T G.992.5 (2009), *Asymmetric digital subscriber line 2 transceivers (ADSL2) – Extended bandwidth ADSL2 (ADSL2plus)*. +- [ITU-T G.993.1] Recommendation ITU-T G.993.1 (2004), *Very high speed digital subscriber line transceivers (VDSL)*. +- [ITU-T G.993.2] Recommendation ITU-T G.993.2 (in force), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [ITU-T G.993.5] Recommendation ITU-T G.993.5 (2010), *Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers*. +- [ITU-T G.994.1] Recommendation ITU-T G.994.1 (in force), *Handshake procedures for digital subscriber line transceivers*. + +- [ITU-T G.997.1] Recommendation ITU-T G.997.1 (2012), *Physical layer management for digital subscriber line transceivers.* +- [ITU-T G.997.2] Recommendation ITU-T G.997.2 (2015), *Physical layer management for G.fast transceivers.* +- [ITU-T G.998.4] Recommendation ITU-T G.998.4 (2010), *Improved impulse noise protection for digital subscriber line (DSL) transceivers.* +- [ITU-T G.8262.1] Recommendation ITU-T G.8262.1 (2022), *Timing characteristics of an enhanced synchronous equipment slave clock* +- [ITU-T G.8264] Recommendation ITU-T G.8264 (2017), *Distribution of timing information through packet networks* +- [ITU-T G.8275] Recommendation ITU-T G.8275 (2020), *Architecture and requirements for packet-based time and phase distribution* +- [ITU-T G.9700] Recommendation ITU-T G.9700 (2014), *Fast access to subscriber terminals (G.fast) – Power spectral density specification.* +- [ITU-T G.9701] Recommendation ITU-T G.9701 (2014), *Fast access to subscriber terminals (G.fast) – Physical layer specification.* +- [ITU-T G.9804.2] Recommendation ITU-T G.9804.2 (2021), *Higher speed passive optical networks: Common transmission convergence layer specification.* +- [ITU-T G.9807.1] Recommendation ITU-T G.9807.1 (2016), *10-Gigabit-capable symmetric passive optical network (XGS-PON).* +- [ITU-T H.248.x] Recommendations ITU-T H.248.x-series, *Gateway control protocol.* +- [ITU-T H.341] Recommendation ITU-T H.341 (1999), *Multimedia management information base.* +- [ITU-T I.112] Recommendation ITU-T I.112 (1993), *Vocabulary of terms for ISDNs.* +- [ITU-T I.363.5] Recommendation ITU-T I.363.5 (1996), *B-ISDN ATM Adaptation Layer specification: Type 5 AAL.* +- [ITU-T M.3100] Recommendation ITU-T M.3100 (2005), *Generic network information model.* +- [ITU-T T.35] Recommendation ITU-T T.35 (2000), *Procedure for the allocation of ITU-T defined codes for non-standard facilities.* +- [ITU-T T.38] Recommendation ITU-T T.38 (2007), *Procedures for real-time Group 3 facsimile communication over IP networks.* +- [ITU-T X.690] Recommendation ITU-T X.690 (2008) | ISO/IEC 8825-1:2008, *Information technology – ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER).* +- [ITU-T X.731] Recommendation ITU-T X.731 (1992) | ISO/IEC 10164-2:1993, *Information technology – Open Systems Interconnection – Systems Management: State management function.* +- [ITU-T X.733] Recommendation ITU-T X.733 (1992) | ISO/IEC 10164-4:1992, *Information technology – Open Systems Interconnection – Systems Management: Alarm reporting function.* + +- [ITU-T Y.1731] Recommendation ITU-T Y.1731 (2008), *OAM functions and mechanisms for Ethernet based networks*. +- [ATIS-0300220] ATIS-0300220.2011, *Representation of the communications industry manufacturers, suppliers, and related service companies for information exchange*. +- [BBF TR-069] Broadband Forum TR-069 Amendment 2 (2007), *CPE WAN management protocol v1.1*. +- [BBF TR-369] Broadband Forum TR-369 Issue 1, Amendment 1 (2019), *User Services Platform (USP)*. +- [ETSI TS 101 270-1] ETSI TS 101 270-1 V1.4.1 (2005), *Transmission and multiplexing (TM); Access transmission systems on metallic access cables; Very high speed digital subscriber line (VDSL); Part 1: Functional requirements*. +- [ETSI TS 101 388] ETSI TS 101 388 V1.4.1 (2007), *Access terminals transmission and multiplexing (ATTM); Access transmission systems on metallic access cables; Asymmetric digital subscriber line (ADSL) – European specific requirements [ITU-T Recommendation G.992.1 modified]*. +- [IEEE 802] IEEE 802-2001 (R2007), *IEEE Standard for local and metropolitan area networks – Overview and architecture*. +- [IEEE 802.1AB] IEEE 802.1AB-2009, *IEEE Standard for local and metropolitan area networks – Station and media access control connectivity discovery*. +- [IEEE 802.1ad] IEEE 802.1ad-2005, *IEEE Standard for local and metropolitan area networks – Virtual bridged local area networks, Amendment 4: Provider bridges*. +- [IEEE 802.1ag] ANSI/IEEE 802.1ag-2007, *IEEE Standard for local and metropolitan area networks – Amendment 5: Connectivity fault management*. +- [IEEE 802.1D] ANSI/IEEE 802.1D-2004, *IEEE Standard for local and metropolitan area networks – Media access control (MAC) bridges*. +- [IEEE 802.1Q] IEEE 802.1Q-2005, *IEEE Standard for local and metropolitan area networks – Virtual Bridged Local Area networks*. +- [IEEE 802.1X] IEEE 802.1X-2004, *IEEE Standard for local and metropolitan area networks – Port-based network access control*. +- [IEEE 802.3] IEEE 802.3-2008, *IEEE Standard for information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications*. +- [IEEE 802.11] IEEE 802.11-2007, *IEEE Standard for information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications*. +- [IEEE 1588] IEEE 1588-2008, *IEEE Standard for a precision clock synchronization protocol for networked measurement and control systems*. +- [IEEE P1904.1] IEEE P1904.1, *Standard for service interoperability in Ethernet passive optical networks (SIEPON)*. + +- [IETF RFC 1213] IETF RFC 1213 (1991), *Management information base for network management of TCP/IP-based internets: MIB-II*. +- [IETF RFC 2236] IETF RFC 2236 (1997), *Internet group management protocol, version 2*. +- [IETF RFC 2464] IETF RFC 2464 (1998), *Transmission of IPv6 packets over Ethernet networks*. +- [IETF RFC 2474] IETF RFC 2474 (1998), *Definition of the differentiated services field (DS field) in the IPv4 and IPv6 headers*. +- [IETF RFC 2579] IETF RFC 2579 (1999), *Textual conventions for SMIPv2*. +- [IETF RFC 2597] IETF RFC 2597 (1999), *Assured forwarding PHB group*. +- [IETF RFC 2617] IETF RFC 2617 (1999), *HTTP authentication: Basic and digest access authentication*. +- [IETF RFC 2684] IETF RFC 2684 (1999), *Multiprotocol encapsulation over ATM adaptation layer 5*. +- [IETF RFC 2685] IETF RFC 2685 (1999), *Virtual private networks identifier*. +- [IETF RFC 2819] IETF RFC 2819 (2000), *Remote network monitoring management information base*. +- [IETF RFC 2863] IETF RFC 2863 (2000), *The interfaces group MIB*. +- [IETF RFC 3246] IETF RFC 3246 (2002), *An expedited forwarding PHB (per-hop behavior)*. +- [IETF RFC 3376] IETF RFC 3376 (2002), *Internet group management protocol, version 3*. +- [IETF RFC 3417] IETF RFC 3417 (2002), *Transport mappings for the simple network management protocol (SNMP)*. +- [IETF RFC 3551] IETF RFC 3551 (2003), *RTP profile for audio and video conferences with minimal control*. +- [IETF RFC 3810] IETF RFC 3810 (2004), *Multicast listener discovery version 2 (MLDv2) for IPv6*. +- [IETF RFC 4133] IETF RFC 4133 (2005), *Entity MIB (version 3)*. +- [IETF RFC 4446] IETF RFC 4446 (2006), *IANA allocations for pseudowire edge to edge emulation (PWE3)*. +- [IETF RFC 4733] IETF RFC 4733 (2006), *RTP payload for DTMF digits, telephony tones, and telephony signals*. +- [IETF RFC 4734] IETF RFC 4734 (2006), *Definition of events for modem, fax, and text telephony signals*. +- [IETF RFC 4789] IETF RFC 4789 (2006), *Simple network management protocol (SNMP) over IEEE 802 networks*. +- [IETF RFC 5519] IETF RFC 5519 (2009), *Multicast group membership discovery MIB*. +- [IETF RFC 5605] IETF RFC 5605 (2009), *Managed objects for ATM over packet switched networks (PSNs)*. +- [ISO/IEC 9798-4] ISO/IEC 9798-4:1999, *Information technology – Security techniques – Entity authentication – Part 4: Mechanisms using a cryptographic check function*. +- [MEF 8] Metro Ethernet Forum MEF 8 (2004), *Implementation agreement for the emulation of PDH circuits over Metro Ethernet networks*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +NOTE – This Recommendation uses the term G-PON to refer generically to PON systems. When a distinction is needed, this Recommendation qualifies the usage with an explicit reference to the appropriate series. + +This Recommendation uses the following terms defined elsewhere: + +- 3.1.1 **10-gigabit-capable passive optical network (XG-PON):** [ITU-T G.987] (See Note to 3.1.) +- 3.1.2 **dynamic bandwidth assignment (DBA):** [ITU-T G.987] +- 3.1.3 **gigabit-capable passive optical network (G-PON):** [ITU-T G.987] (See Note to 3.1.) +- 3.1.4 **mean optical launch power:** [ITU-T G.987] +- 3.1.5 **ONU management and control interface (OMCI):** [ITU-T G.987] +- 3.1.6 **optical line termination (OLT):** [ITU-T G.987] +- 3.1.7 **optical network unit (ONU):** [ITU-T G.987] +- 3.1.8 **passive optical network (PON) system:** [ITU-T G.987] +- 3.1.9 **physical layer OAM (PLOAM):** [ITU-T G.987] +- 3.1.10 **ranging:** [ITU-T G.987] +- 3.1.11 **transmission container (T-CONT):** [ITU-T G.987] +- 3.1.12 **user-network interface (UNI):** [ITU-T I.112] + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +- 3.2.1 **downstream:** The direction of traffic flow from an optical line termination (OLT) to the optical network unit (ONU). +- 3.2.2 **policing:** A process that causes a flow of input packets to conform to a given peak information rate (PIR)/peak burst size (PBS) by immediately dropping packets that exceed PIR/PBS. This typically results in packet loss; packets may be further marked as drop eligible if they exceed the committed information rate (CIR)/committed burst size (CBS). +- 3.2.3 **shaping:** A process that causes a flow of input packets to conform to a given peak information rate (PIR)/peak burst size (PBS) by controlling the release rate/burst size of output packets. This typically results in a queueing delay; packets may be dropped if there is a queue overflow because the input rate or burst size is too great. +- 3.2.4 **upstream:** The direction of traffic flow from an optical line termination (ONU) to the optical network unit (OLT). + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|------|---------------------------------------------| +| AAL | Asynchronous transfer mode Adaptation Layer | +| ACK | Acknowledgement | +| ACS | Autoconfiguration Server | +| ADSL | Asymmetric Digital Subscriber Line | +| AES | Advanced Encryption Standard | + +| | | +|----------|-------------------------------------------------------------------------------| +| AF | Assured Forwarding | +| AIS | Alarm Indication Signal | +| AK | Acknowledgement | +| AMCC | Auxiliary Management and Control Channel | +| ANI | Access Node Interface | +| ANI-E | Access Network Interface supported by an EPON ONU | +| ANI-G | Access Network Interface supported by a G-PON ONU | +| AR | Acknowledge Request | +| ARC | Alarm-Reporting Control | +| ARP | Address Resolution Protocol | +| ASCII | American Standard Code for Information Interchange | +| ATA | Analogue Telephony Adaptor | +| ATM | Asynchronous Transfer Mode | +| ATU-C | Asymmetric digital subscriber line Transceiver Unit, Central office (ONU) end | +| ATU-R | Asymmetric digital subscriber line Transceiver Unit, Remote terminal end | +| AVC | Attribute Value Change | +| BE | Best Effort | +| BER | Bit Error Rate | +| BES | Burst Errored Second | +| BIP | Bit-Interleaved Parity | +| BNG | Broadband Network Gateway | +| B-PON | Broadband Passive Optical Network | +| CAS | Channel Associated Signalling | +| CBS | Committed Burst Size | +| CCM | Continuity Check Message | +| CES | Circuit Emulation Service | +| CFI | Canonical Format Indicator | +| CFM | Configuration Fault Management | +| CIR | Committed Information Rate | +| CLEI | Common Language Equipment Identification | +| CLP | Cell Loss Priority | +| CMAC | Cipher-based Message Authentication Code | +| CoS | Class of Service | +| CPCS-SDU | Common Part Convergence Sublayer Service Data Unit | +| CPCS-UU | Common Part Convergence Sublayer User-to-User indication | +| CPE | Customer Premises Equipment | + +| | | +|---------|--------------------------------------------| +| CPI | Common Part Indicator | +| CRC | Cyclic Redundancy Check | +| CS | Convergence Sublayer | +| CSS | Controlled Slip Seconds | +| CTP | Connection Termination Point | +| DA | Destination Address | +| DAD | Duplicate Address Detection | +| DBA | Dynamic Bandwidth Assignment | +| DBDT | Draw-Break Dial Tone | +| DEI | Discard Eligibility Indicator (bit) | +| DHCP | Dynamic Host Configuration Protocol | +| DMT | Discrete Multi-Tone, xDSL | +| DNS | Domain Name Server | +| DRT | Data Rate Threshold | +| DS | Downstream | +| DSCP | Differentiated Services Code Point | +| DSL | Digital Subscriber Line | +| DSLAM | Digital Subscriber Line Access Multiplexer | +| DUID | DHCP Unique Identifier | +| DWLCH | Downstream Wavelength Channel | +| ECB | Electronic Codebook | +| ECID | Emulated Circuit ID | +| EF | Expedited Forwarding | +| EFM | Ethernet in the First Mile | +| EIR | Excess Information Rate | +| EMS | Element Management System | +| eoc | embedded operations channel | +| EPON | Ethernet Passive Optical Network | +| ES | Errored Second | +| ESMC | Ethernet Synchronization Message Channel | +| ES-L | Errored Second-Line | +| ES-LFE | Errored Second-Line Far End | +| ES-NP | Errored Second-Network Performance | +| ES-NPFE | Errored Second-Network Performance Far End | +| ES-P | Errored Second-Path | +| ES-PFE | Errored Second-Path Far End | +| EVC | Ethernet Virtual Connection | + +| | | +|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| EVS | Ethernet Virtual Service | +| FAST | Fast Access to Subscriber Terminal (G.fast) | +| FCS | Frame Check Sequence | +| FDL | Facility Data Link | +| FE | Far End | +| FEFE | Far End Block Error | +| FEC | Forward Error Correction | +| FRU | Field-Replaceable Unit | +| FTTx | Fibre to the x (B – building, business; H – home; C – cabinet, curb) | +| FS | Framing Sublayer | +| GAL | GEM Adaptation Layer | +| GARP | Generic Attribute Registration Protocol | +| GEM | Gigabit-capable passive optical network Encapsulation Method
NOTE – See [ITU-T G.984.x]. Unless explicitly stated otherwise, this term also refers generically to XGEM encapsulation. | +| G-PON | Gigabit-capable Passive Optical Network
NOTE – See [ITU-T G.984.x]. Unless explicitly stated otherwise, this term also refers generically to [ITU-T G.987] XG-PON. | +| GSP | Generic Status Portal | +| GTC | Gigabit-capable passive optical network Transmission Convergence layer [ITU-T G.984.x]
NOTE – Unless explicitly stated otherwise, this term also refers generically to XGTC. | +| HEC | Header Error Check | +| HSP | High Speed PON | +| IA_NA | Identity Association for Non-temporary Addresses
NOTE – See [b-IETF RFC 3315]. | +| IAT | Inter-Arrival Time, xDSL | +| ICMP | Internet Control Message Protocol | +| ID | Identifier | +| IF | Interface | +| IGMP | Internet Group Management Protocol
NOTE – IGMP may also refer generically to IPv6 MLD. | +| INM | Impulse Noise Monitoring | +| INP | Impulse Noise Protection | +| IP | Internet Protocol | +| IPHC | IP Host Config | +| IW | Interworking | +| KEK | Key Encryption Key | +| L2-OCM | Layer 2 OMCI Common Model | + +| | | +|-------|-----------------------------------------------------| +| LAN | Local Area Network | +| LASP | Link Aggregation Service Profile | +| LBM | Loopback Message | +| LBO | Line Build-Out | +| LBR | Loopback Reply | +| LCD | Loss of Cell Delineation | +| LCT | Local Craft Terminal | +| LIM | Line Interface Module | +| LINIT | Line Initialization failure | +| LL | Limited Link | +| LLC | Link Layer Control | +| LLID | Logical Link ID | +| LMIG | Layer Management Indication Generation | +| LMIR | Layer Management Indication Receiving | +| LODS | Loss Of Downstream Synchronization | +| LOF | Loss Of Frame | +| LOID | Logical ONU ID | +| LOL | Loss Of Link | +| LOM | Loss-Of-Margin | +| LOR | Loss Of RMC | +| LOS | Loss Of Signal | +| LPR | Loss of Power | +| LSB | Least Significant Bit | +| LTM | Linktrace Message | +| LTR | Linktrace Reply | +| MA | Maintenance Association | +| MAC | Medium Access Control | +| MD | Maintenance Domain | +| MDU | Multiple Dwelling Unit | +| ME | Managed Entity | +| MEG | Maintenance Entity Group | +| MEP | Maintenance association End Point | +| MGC | Media Gateway Controller | +| MHF | Maintenance domain intermediate point Half Function | +| MIB | Management Information Base | +| MIC | Message Integrity Check | +| MIP | Maintenance domain Intermediate Point | + +| | | +|--------|---------------------------------------------------------------------------------------------------| +| MLD | Multicast Listener Discovery
NOTE – MLD is sometimes included generically in the acronym IGMP. | +| MLT | Mechanized Loop Test(ing) | +| MoCA | Multimedia Over Coax Alliance | +| MP | Maintenance Point | +| MPCPDU | Multi-Point Control Protocol Data Unit | +| MSB | Most Significant Bit | +| MT | Message Type | +| MTU | Maximum Transmission Unit | +| NACK | Negative Acknowledgement | +| NCD | No Cell Delineation | +| NE | Near End | +| NSCds | Number of xDSL Subcarriers, downstream | +| NSCus | Number of xDSL Subcarriers, upstream | +| OA | Optical Amplifier/Amplification | +| OAM | Operations, Administration and Maintenance | +| OEO | Optical-Electrical-Optical | +| OID | Object Identifier | +| OLR | On-Line Reconfiguration | +| OLT | Optical Line Termination | +| OMCC | Optical network unit Management and Control Channel | +| OMCI | Optical network unit Management and Control Interface | +| OMI | Optical Modulation Index | +| ONT | Optical Network Termination | +| ONU | Optical Network Unit | +| OOF | Out Of Frame | +| OOS | Out Of Sync | +| OS | Operations System | +| OTL | Optical Trunk Line | +| OUI | Organizationally Unique Identifier | +| PBS | Peak Burst Size | +| PCP | Priority Code Point | +| PD | Powered Device | +| PDU | Protocol Data Unit | +| PHY | Physical interface | +| PIR | Peak Information Rate | +| PLOAM | Physical Layer Operations, Administration and Maintenance | + +| | | +|-------|---------------------------------------| +| PM | Performance Monitoring | +| PME | Physical Medium Entity | +| PoE | Power over Ethernet | +| PON | Passive Optical Network | +| POTS | Plain Old Telephone Service | +| PPPoE | Point-to-Point Protocol over Ethernet | +| PPTP | Physical Path Termination Point | +| PSBd | Physical Sync Block-downstream | +| PSD | Power Spectral Density | +| PSE | Power-Sourcing Equipment | +| PSK | Pre-shared Secret Key | +| PSN | Packet-Switched Network | +| QLN | Quiet Line Noise | +| QoS | Quality of Service | +| RA | Router Advertisement | +| RAB | Rate Adaptation Buffer | +| RAD | Rate Adaptation - Downshift | +| RAU | Rate Adaptation - Upshift | +| RDI | Remote Defect Indication | +| RE | Reach Extender | +| REN | Ringer Equivalent Number | +| REIN | Repetitive Electrical Impulse Noise | +| RF | Radio Frequency | +| RFI | Radio Frequency Interference | +| RG | Residential Gateway | +| RMC | Robust Management Channel | +| RO | Read Only | +| ROC | Robust Operations Channel | +| ROH | Receiver Off Hook | +| RS | Router Solicitation | +| RTCP | Real-time Transport Control Protocol | +| RTP | Real-Time Protocol | +| RW | Read, Write | +| RWSC | Read, Write, Set-by-Create | +| SAR | Segmentation And Reassembly | +| SD | Signal Degrade | +| SDH | Synchronous Digital Hierarchy | + +| | | +|----------|------------------------------------------------------| +| SDU | Service Data Unit | +| SES | Severely Errored Second | +| SES-L | Severely Errored Second-Line | +| SES-LFE | Severely Errored Second-Line Far End | +| SES-NP | Severely Errored Second-Network Performance | +| SES-NPFE | Severely Errored Second-Network Performance, Far End | +| SES-P | Severely Errored Second-Path | +| SES-PFE | Severely Errored Second-Path Far End | +| SF | Signal Fail | +| SHINE | Single High Impulse Noise Event | +| SIP | Session Initiation Protocol | +| SLA | Service Level Agreement | +| SLAAC | Stateless Address Autoconfiguration | +| SNMP | Simple Network Management Protocol | +| SNR | Signal-to-Noise Ratio | +| SOS | Save Our Showtime | +| SPR | Snooping with Proxy Reporting | +| SRA | Seamless Rate Adaptation | +| SSCOP | Service Specific Connection Oriented Protocol | +| SSCS | Service Specific Convergence Sublayer | +| TC | Transmission Convergence | +| TCA | Threshold Crossing Alert | +| TCI | Tag Control Information | +| T-CONT | Transmission Container | +| TCP | Transmission Control Protocol | +| TDM | Time Division Multiplex | +| TLP | Transmission Level Point | +| TLV | Type-Length-Value | +| ToD | Time of Day | +| TP | Termination Point | +| TQ | Time Quantum | +| trTCM | two-rate Three Colour Marker | +| TTL | Time To Live | +| TWDM | Time and Wavelength Division Multiplexing | +| UA | User Agent | +| UAS | Unavailable Second | +| UAS-NP | Unavailable Second-Network Performance | + +| | | +|----------|-------------------------------------------------------------------------------------------------------------------------------------| +| UAS-NPFE | Unavailable Second-Network Performance Far End | +| UAS-P | Unavailable Second (-L: -line, -P: -path, -FE: -far-end) | +| UDP | User Datagram Protocol | +| UNI | User Network Interface | +| UNI-G | User Network Interface supported by Gigabit-capable passive optical network encapsulation method | +| UPBO | Upstream Power Back-Off | +| US | Upstream | +| VBES | VLANs for Business Ethernet Services | +| VC | Virtual Circuit | +| VCC | Virtual Circuit Connection | +| VCI | Virtual Circuit Identifier | +| VDSL | Very high speed Digital Subscriber Line
NOTE – ITU-T G.993.2 VDSL2 is managed under the xDSL family of MEs. | +| VEIP | Virtual Ethernet Interface Point | +| VID | Virtual local area network Identifier | +| VLAN | Virtual Local Area Network | +| VoIP | Voice Over Internet Protocol | +| VP | Virtual Path | +| VPI | Virtual Path Identifier | +| VPN | Virtual Private Network | +| VRP | Video Return Path | +| VTU | VDSL2 Transceiver Unit | +| VTU-O | Very high-speed digital subscriber line Transceiver Unit, Operator end | +| VTU-R | Very high-speed digital subscriber line Transceiver Unit, Remote end | +| WFQ | Weighted Fair Queueing | +| WLCP | Wavelength Channel Protection | +| WRR | Weighted Round Robin | +| xDSL | x Digital Subscriber Line
NOTE – This is an inclusive term for any of the DSL Recommendations, excluding [ITU-T G.993.1]. | +| XGEM | XG-PON Encapsulation Method
NOTE – See [ITU-T G.987]. Sometimes this abbreviation is included generically under the acronym GEM. | +| XG-PON | 10 Gigabit-capable Passive Optical Network | +| XML | extensible Markup Language | +| xTU-C | x digital subscriber line Transceiver Unit at the Central office end | + +NOTE – This is used as a generic term referring to both the asymmetric digital subscriber line transceiver unit, central office (ONU) end (ATU-C of the ITU-T G.992.x series and the very high-speed digital subscriber line transceiver unit, operator end (VTU-O) of [ITU-T G.993.2]. + +xTU-R x digital subscriber line Transceiver Unit at the Remote end + +NOTE – This is used as a generic term referring to both the asymmetric digital subscriber line transceiver unit, remote terminal end (ATU-R of the ITU-T G.992.x series and the VTU-R of [ITU-T G.993.2]. + +# 5 Conventions + +In bit vectors indicated in this Recommendation, the rightmost bit is bit 1. This represents the least significant bit (LSB), while bit 8 represents the most significant bit (MSB) within a byte. If the bit vector is made up of more than one byte, then bit numbering starts from the least significant byte onwards. + +In attribute descriptions that refer to the Boolean values *true* and *false*, true is coded as 0x01 in hexadecimal and false is coded as 0x00. A Boolean attribute is always one byte. + +In attribute descriptions that refer to spaces, the American standard code for information interchange (ASCII) space character (value 0x20) must be used for the entire size of the attribute. + +An *ASCII string* is a sequence of ASCII encoded characters, terminated by the null character (0x00). If a string occupies the entire allocated size of an attribute, the terminating null is not required. + +This Recommendation frequently states that the OLT makes certain decisions or takes certain actions. While the OMCI commands may emanate from the OLT, there is no implication that the actual decision or action impetus comes from logic internal to the OLT, rather than from a separate management system or a human operator. + +When [ITU-T G.987] is referenced in this Recommendation, it applies generically to [ITU-T G.9807.1] XGS-PON, [ITU-T G.989.3] NG-PON2, and [ITU-T G.9804.2] ComTC, unless otherwise specified. When a particular clause of [ITU-T G.987.3] is referenced in this Recommendation, it applies generically to the analogous clause of [ITU-T G.9807.1], [ITU-T G.989.3], and [ITU-T G.9804.2], unless otherwise specified. + +# 6 Reference model and terms + +## 6.1 OMCI in the access network + +The network architecture reference model for PON is described in the applicable ITU-T GTC based PON system specification. An access system according to [ITU-T G.986] has a single ONU on each fibre subtended from the OLT. + +The OMCI fits into the overall model for an access network system as illustrated in Figure 6.1-1. The dotted line shows a path for OMCI signals between an OLT and ONU. + +![Figure 6.1-1 – Reference model, OMCI. The diagram shows an OLT connected to an ODN via an S/R PON interface. The ODN is connected to two ONUs via R/S PON interfaces. A dotted line represents the OMCC path from the OLT to each ONU. A legend indicates that solid lines represent physical links and dotted lines represent the OMCC of each ONU. The diagram is labeled G.988(12)_F6.1-1.](2876be3592c7b4878400b85f209b2b6a_img.jpg) + +The diagram illustrates the reference model for OMCI in an access network. On the left, an OLT (Optical Line Terminal) is shown. It is connected to an ODN (Optical Distribution Network) via an S/R PON interface. The ODN is connected to two ONUs (Optical Network Units) via R/S PON interfaces. A dotted line represents the OMCC (Optical Management Communication Channel) path from the OLT to each ONU. A legend at the bottom indicates that a solid line represents a physical link and a dotted line represents the OMCC of each ONU. The diagram is labeled G.988(12)\_F6.1-1. + +Figure 6.1-1 – Reference model, OMCI. The diagram shows an OLT connected to an ODN via an S/R PON interface. The ODN is connected to two ONUs via R/S PON interfaces. A dotted line represents the OMCC path from the OLT to each ONU. A legend indicates that solid lines represent physical links and dotted lines represent the OMCC of each ONU. The diagram is labeled G.988(12)\_F6.1-1. + +Figure 6.1-1 – Reference model, OMCI + +## 6.2 ONU functions + +As shown in Figure 6.2-1, the functions of the ONU are: + +- access network line termination; +- user network interface (UNI) line termination, noting that in the fibre to the business case, the UNIs from one ONU may belong to different users; +- service multiplexing and de-multiplexing. + +![Figure 6.2-1 – ONU functional block diagram. The diagram shows the internal components of an ONU. On the left, an 'ANI' (Access Network Interface) connects to an 'AN LT' (Access Network Line Termination). Below the ANI connection, a note states 'Optional second ANI can be supported for survivability'. The 'AN LT' connects to a central 'Service multiplex and demultiplex' block, represented by a trapezoid. This block connects to two 'UNI LT' (User Network Interface Line Termination) blocks, which are stacked vertically and connected by a dashed line. Each 'UNI LT' block connects to a 'UNI' (User Network Interface) on the right. The entire diagram is labeled 'G.988(12)_F6.2-1' at the bottom right.](e180f2b5fcbe8001554a7c0677cd3f82_img.jpg) + +Figure 6.2-1 – ONU functional block diagram. The diagram shows the internal components of an ONU. On the left, an 'ANI' (Access Network Interface) connects to an 'AN LT' (Access Network Line Termination). Below the ANI connection, a note states 'Optional second ANI can be supported for survivability'. The 'AN LT' connects to a central 'Service multiplex and demultiplex' block, represented by a trapezoid. This block connects to two 'UNI LT' (User Network Interface Line Termination) blocks, which are stacked vertically and connected by a dashed line. Each 'UNI LT' block connects to a 'UNI' (User Network Interface) on the right. The entire diagram is labeled 'G.988(12)\_F6.2-1' at the bottom right. + +**Figure 6.2-1 – ONU functional block diagram** + +## 6.3 Support of multicast connection + +Multicast traffic can be supported in an optical access network. While a GEM port-ID is assigned to a single UNI in a unicast connection, a GEM port-ID is shared by multiple UNIs in multiple ONUs in a multicast connection. The multicast connection set-up process is the same as the unicast connection set-up process. It is the responsibility of the OLT to manage the members of a multicast group and control the multicast connection in ONUs. + +In the downstream direction of G-PON, a multicast connection is useful for bandwidth savings. On the other hand, in the upstream direction, it is impossible to support a multicast connection with a shared port-ID because the OLT could not reassemble segmented GEM packets correctly if it received several GEM packets with the same port-ID from different ONUs. Therefore, upstream traffic associated with a multicast service must be sent to the OLT over a separate unicast connection. + +## 6.4 Voice over Internet protocol management + +While the OMCI is always used to manage PON services and ONU equipment, a voice Over Internet protocol (VoIP) service may optionally be managed by means external to the OMCI. This allows operators more flexibility in choosing how to manage their overall VoIP service, regardless of the access technology involved. A VoIP service on an ONU may be managed via one of two paths: + +- OMCI path – OMCI has full view and control of all VoIP service attributes; +- Internet protocol (IP) path – OMCI is only used to configure attributes that allow non-OMCI based control of VoIP service attributes. + +Specifically, if the OMCI path is used to manage a VoIP service, all of the managed entities (MEs) defined here may be read or written. + +If the IP path is used to manage an session initiation protocol (SIP) VoIP service, only the following SIP-related MEs may be read or written (all other MEs are unaffected): + +- IP host config data; +- IP host performance monitoring (PM) history data; +- VoIP config data; +- physical path termination point (PPTP) plain old telephone service (POTS) UNI; +- call control PM history data; + +- real-time protocol (RTP) PM history data; +- SIP call initiation PM history data; +- SIP agent PM history data; +- SIP config portal; +- VoIP line status. + +If the IP path is used to manage an ITU-T H.248 VoIP service, only the following ITU-T H.248-related MEs may be read or written (all other MEs are unaffected): + +- IP host config data; +- IP host PM history data; +- VoIP config data; +- PPTP POTS UNI; +- Call control PM history data; +- RTP PM history data; +- MGC PM history data; +- ITU-T H.248 config portal; +- VoIP line status. + +# 7 Requirements of the management interface specification + +The ONU management and control interface defined by this Recommendation is used by the OLT to manage the ONU in the following areas: + +- a) configuration management +- b) fault management +- c) performance management +- d) security management. + +This interface allows the OLT to: + +- a) establish and release connections across the ONU; +- b) manage the UNIs at the ONU; +- c) request configuration information and performance statistics. + +The OMCI also allows the ONU to inform the OLT autonomously of alarms, performance threshold crossings and changes to the values of many of the MIB attributes. + +The OMCI protocol is asymmetric: the controller in the OLT is the master, while the ONU is the slave. A single OLT controller using multiple instances of the protocol over separate control channels typically controls multiple ONUs. + +In G-PON, the OMCI protocol runs across a GEM connection between the OLT controller and the ONU controller. The GEM connection is established at ONU initialization. OMCI transport in ITU-T G.986 applications is defined in [ITU-T G.986]. + +## 7.1 Configuration management + +Configuration management provides functions to identify the ONU's capabilities and to exercise control over the ONU. Areas of management include configuration of: + +- a) equipment; +- b) PON and reach extender (RE) protection; + +- c) the UNIs; +- d) GEM port network CTPs in G-PON applications; +- e) interworking termination points (TPs); +- f) operations, administration and maintenance (OAM) flows; +- g) physical ports; +- h) GEM adaptation layer (GAL) profiles in G-PON applications; +- i) service profiles; +- j) traffic descriptors; +- k) asynchronous transfer mode adaptation layer (AAL) profiles, when needed for asymmetric digital subscriber line (ADSL) UNIs. + +All G-PON ONUs support GEM transport of user traffic. There is only one connection model for GEM transport, which is the simple point-to-point transfer of user data via a GEM connection across the PON, and with downstream multicast capability. GEM interworking (IW) always occurs in the OLT and the ONU, and GEM never extends beyond the PON link. + +When the ONU supports an asynchronous transfer mode (ATM) UNI (ADSL), the ATM connection from the subscriber terminates at the ONU. The OMCI supports the required configuration methods to manage this function. + +## 7.2 Fault management + +As modelled by the OMCI, the ONU detects and reports equipment, software and interface failures and declares the corresponding alarms. The OMCI supports failure reporting on many MEs as described in clause 9. An alarm table is defined for each of these entities. + +To avoid erratic floods of alarm messages, it is common to filter, or soak, defects such as facility impairments before declaring them as alarms, and to soak defect clearing before retiring the alarm. The declaration soak time is typically $2.5 \pm 0.5$ s, while the retirement soak time is typically $10.5 \pm 0.5$ s. Which alarms are to be soaked, and what the soak intervals should be, are regarded as vendor-specific choices. Interoperability considerations, however, require that alarms be soaked exactly once, either at the OLT or at the ONU. This Recommendation specifies that they be soaked at the ONU. + +In addition to failure reporting, the OMCI supports test, measurement and in-service monitoring, including: + +- a) metallic tests of copper drops (voice or x digital subscriber line (xDSL)); +- b) optical and other parameters of the optical distribution network; +- c) [IEEE 802.1ag] connectivity fault management; +- d) directed loopback, e.g., of DS1/E1 services. + +The OMCI also provides for the reporting of protection switch events. + +## 7.3 Performance management + +The ONU has only limited PM. The OMCI supports PM using a number of MEs that are described throughout clause 9. These MEs can be identified by the words "performance monitoring history data" or "extended PM" in their names. + +All PM-related MEs are created at the request of the OLT. + +All history data are maintained in the OLT. The ONU maintains only a current counter and one 15 min previous-interval counter. + +Clause I.4 describes PM in detail. + +## 7.4 Security management + +Different access technologies specify differing degrees of security capability. The OMCI supports a mechanism to allow mutual authentication of the OLT and ONU and subsequent secure communication of encryption keys. + +# 8 Protocol-independent MIB for the OMCI + +The OMCI is defined such that vendors can offer modular, incremental capabilities to meet different levels of customer needs. This Recommendation defines a protocol necessary to support capabilities specified in the relevant PON specifications, as well as a variety of services and features. The OMCI supports interoperability, yet it allows for optional components and future extensions. + +A protocol-independent MIB describes the exchange of information across the OMCI. Clause 8.1 lists the MEs and illustrates key relationships between them to implement some of the important features that may be offered by ONUs. Clause 9 defines each ME in detail. + +## 8.1 Managed entities + +The protocol-independent MIB presented in this Recommendation is defined in terms of MEs. MEs are abstract representations of resources and services in an ONU. Only a small subset of the list of MEs is mandatory. The existence of other MEs depends on the architecture and feature set supported by the vendor. + +Table 8-1 lists all the MEs. The designation M in a column indicates that the specified ME is mandatory for systems complying with the corresponding Recommendation. The designation M/E in a column indicates that the corresponding ME is mandatory and that its definition is adapted to [IEEE 802.3] applications in accordance with Annex C. N/A indicates that the specified ME is not applicable. Other MEs are present according to the architecture and the feature set offered by a given ONU. + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------|------------------------------------------------------------|------------------------------------------------|----------------|----------------|-----------------------------|-----------------| +| 9.13.6 | AAL5 performance monitoring history data | | | | N/A | | +| 9.13.5 | AAL5 profile | | | | N/A | | +| 9.2.19 | ANI-E | | | | M | | +| 9.2.1 | ANI-G | M | M | | M | M | +| 9.12.10 | Attribute | | | | | | +| 9.12.4 | Authentication security method | | | | | | +| 9.12.16 | BBF TR-069 management server | | | | | | +| 9.9.12 | Call control performance monitoring history data | | | | | | +| 9.1.5 | Cardholder | M | M | | M | M | +| 9.8.4 | CES physical interface performance monitoring history data | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|--------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.8.12 | CES physical interface performance monitoring history data 2 | | | | | | +| 9.8.13 | CES physical interface performance monitoring history data 3 | | | | | | +| 9.8.3 | CES service profile | | | | | | +| 9.1.6 | Circuit pack | | | | | | +| 9.7.40 | Data gathering line test, diagnostic and status | | | | | | +| 9.3.18 | Dot1 rate limiter | | | | | | +| 9.3.25 | Dot1ag CFM stack | | | | | | +| 9.3.26 | Dot1ag chassis-management info | | | | | | +| 9.3.21 | Dot1ag default MD level | | | | | | +| 9.3.20 | Dot1ag maintenance association | | | | | | +| 9.3.19 | Dot1ag maintenance domain | | | | | | +| 9.3.22 | Dot1ag MEP | | | | | | +| 9.3.24 | Dot1ag MEP CCM database | | | | | | +| 9.3.23 | Dot1ag MEP status | | | | | | +| 9.3.15 | Dot1X configuration profile | | | | | | +| 9.3.16 | Dot1X performance monitoring history data | | | | | | +| 9.3.14 | Dot1X port extension package | | | | | | +| 9.7.41 | EFM bonding group | | | | | | +| 9.7.43 | EFM bonding group performance monitoring history data | | | | | | +| 9.7.44 | EFM bonding group performance monitoring history data part 2 | | | | | | +| 9.7.42 | EFM bonding link | | | | | | +| 9.7.45 | EFM bonding link performance monitoring history data | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|---------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.7.46 | EFM bonding port performance monitoring history data | | | | | | +| 9.7.47 | EFM bonding port performance monitoring history data part 2 | | | | | | +| 9.2.14 | Energy consumption performance monitoring history data | | | | | | +| 9.2.22 | Enhanced FEC performance monitoring history data | | | | | | +| 9.13.11 | Enhanced security control | | | | | | +| 9.2.23 | Enhanced TC performance monitoring history data | | | | | | +| 9.2.20 | EPON downstream performance monitoring configuration | | | | | | +| 9.1.9 | Equipment extension package | | | | | | +| 9.1.11 | Equipment protection profile | | | | | | +| 9.8.9 | Ethernet flow termination point | | | | | | +| 9.3.32 | Ethernet frame extended PM | | | | | | +| 9.3.34 | Ethernet frame extended PM 64 Bit | | | | | | +| 9.3.31 | Ethernet frame performance monitoring history data downstream | | | | | | +| 9.3.30 | Ethernet frame performance monitoring history data upstream | | | | | | +| 9.5.2 | Ethernet performance monitoring history data | | | | | | +| 9.5.3 | Ethernet performance monitoring history data 2 | | | | | | +| 9.5.4 | Ethernet performance monitoring history data 3 | | | | | | +| 9.8.18 | Ethernet pseudowire parameters | | | | | | +| 9.3.13 | Extended VLAN tagging operation configuration data | | | | | | +| 9.7.49 | FAST line configuration profile part 1 | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|----------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.7.50 | FAST line configuration profile part 2 | | | | | | +| 9.7.51 | FAST line configuration profile part 3 | | | | | | +| 9.7.52 | FAST line configuration profile part 4 | | | | | | +| 9.7.53 | FAST channel configuration profile, part 1 | | | | | | +| 9.7.53.1 | FAST channel configuration profile, part 2 | | | | | | +| 9.7.54 | FAST data path configuration profile | | | | | | +| 9.7.55 | FAST vectoring line configuration extensions | | | | | | +| 9.7.56 | FAST line inventory and status data, part 1 | | | | | | +| 9.7.57 | FAST line inventory and status data part 2 | | | | | | +| 9.7.58 | FAST xTU-C performance monitoring history data | | | | | | +| 9.7.59 | FAST xTU-R performance monitoring history data | | | | | | +| 9.7.60 | FAST line failures performance monitoring data | | | | | | +| 9.2.9 | FEC performance monitoring history data | | | | | | +| 9.12.13 | File transfer controller | | | | | | +| 9.2.8 | GAL Ethernet performance monitoring history data | | | | N/A | | +| 9.2.7 | GAL Ethernet profile | | | | N/A | | +| 9.2.4 | GEM interworking termination point | M | M | | M/E | M | +| 9.2.3 | GEM port network CTP | M | M | | M/E | M | +| 9.2.13 | GEM port network CTP performance monitoring history data | | | | N/A | | +| 9.12.12 | General purpose buffer | | | | | | +| 9.12.14 | Generic status portal | | | | | | +| 9.3.10 | IEEE 802.1p mapper service profile | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|--------------------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.13.4 | Interworking VCC termination point | | | | | | +| 9.4.1 | IP host config data | | | | | | +| 9.4.2 | IP host performance monitoring history data | | | | | | +| 9.4.5 | IPv6 host config data | | | | | | +| 9.2.18 | L2 multicast GEM interworking termination point | | | | | | +| 9.12.5 | Large string | | | | | | +| 9.3.35 | Link aggregation service profile | | | | | | +| 9.8.2 | Logical $N \times 64$ kbit/s sub-port connection termination point (CTP) | | | | | | +| 9.3.2 | MAC bridge configuration data | | | | | | +| 9.3.3 | MAC bridge performance monitoring history data | | | | | | +| 9.3.8 | MAC bridge port bridge table data | | | | | | +| 9.3.4 | MAC bridge port configuration data | | | | | | +| 9.3.5 | MAC bridge port designation data | | | | | | +| 9.3.7 | MAC bridge port filter pre-assign table | | | | | | +| 9.3.6 | MAC bridge port filter table data | | | | | | +| 9.3.33 | MAC bridge port ICMPv6 process pre-assign table | | | | | | +| 9.3.9 | MAC bridge port performance monitoring history data | | | | | | +| 9.3.1 | MAC bridge service profile | | | | | | +| 9.12.9 | Managed entity | | | | | | +| 9.9.16 | MGC config data | | | | | | +| 9.9.20 | MGC config portal | | | | | | +| 9.9.17 | MGC performance monitoring history data | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|-----------------------------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.10.2 | Multimedia over coax alliance (MoCA) Ethernet performance monitoring history data | | | | | | +| 9.10.3 | MoCA interface performance monitoring history data | | | | | | +| 9.8.14 | MPLS pseudowire termination point | | | | | | +| 9.2.5 | Multicast GEM interworking termination point | | | | | | +| 9.3.27 | Multicast operations profile | | | | | | +| 9.3.28 | Multicast subscriber config info | | | | | | +| 9.3.29 | Multicast subscriber monitor | | | | | | +| 9.12.3 | Network address | | | | | | +| 9.9.10 | Network dial plan table | | | | | | +| 9.12.11 | Octet string | | | | | | +| 9.12.2 | OLT-G | | | | | | +| 9.12.8 | OMCI | | | | | | +| 9.1.3 | ONU data | M | M | M | M | M | +| 9.1.14 | ONU dynamic power management control | | | | | | +| 9.1.16 | ONU manufacturing data | | | | | | +| 9.1.7 | ONU power shedding | | | | | | +| 9.1.12 | ONU remote debug | | | | | | +| 9.1.17 | ONU time configuration | | | | | | +| 9.1.2 | ONU2-G | M | M | | M | M | +| 9.1.15 | ONU3-G | | M | | | M | +| 9.1.13 | ONU-E | | | M | N/A | | +| 9.1.1 | ONU-G | M | M | | M | M | +| 9.1.19 | ONU4-G | | | | | M | +| 9.12.18 | OpenFlow config data | | | | | | +| 9.8.1 | Physical path termination point CES UNI | | | | | | +| 9.5.1 | Physical path termination point Ethernet UNI | | | M | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|---------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.13.3 | Physical path termination point LCT UNI | | | | | | +| 9.10.1 | Physical path termination point MoCA UNI | | | | | | +| 9.9.1 | Physical path termination point POTS UNI | | | | | | +| 9.14.2 | Physical path termination point RE UNI | | | | | | +| 9.15.1 | Physical path termination point RS232/RS485 UNI | | | | | | +| 9.13.2 | Physical path termination point video ANI | | | | | | +| 9.13.1 | Physical path termination point video UNI | | | | | | +| 9.7.1 | Physical path termination point xDSL UNI part 1 | | | | | | +| 9.7.2 | Physical path termination point xDSL UNI part 2 | | | | | | +| 9.7.48 | Physical path termination point UNI part 3 (FAST) | | | | | | +| 9.5.6 | Power over Ethernet (PoE) control | | | | | | +| 9.1.8 | Port-mapping package | | | | | | +| 9.2.10 | Priority queue | | | | | | +| 9.1.10 | Protection data | | | | | | +| 9.8.7 | Pseudowire maintenance profile | | | | | | +| 9.8.8 | Pseudowire performance monitoring history data | | | | | | +| 9.8.5 | Pseudowire termination point | | | | | | +| 9.7.32 | PTM performance monitoring history data xDSL | | | | | | +| 9.8.15 | PW ATM configuration data | | | | | | +| 9.8.16 | PW ATM performance monitoring history data | | | | | | +| 9.8.17 | PW Ethernet configuration data | | | | | | +| 9.3.17 | Radius performance monitoring history data | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|--------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.14.1 | RE ANI-G | | | | | | +| 9.14.6 | RE common amplifier parameters | | | | | | +| 9.14.5 | RE config portal | | | | | | +| 9.14.4 | RE downstream amplifier | | | | | | +| 9.14.3 | RE upstream amplifier | | | | | | +| 9.15.2 | RS232/RS485 performance monitoring history data | | | | | | +| 9.15.3 | RS232/RS485 Port Operation Configuration data | | | | | | +| 9.9.13 | RTP performance monitoring history data | | | | | | +| 9.9.7 | RTP profile data | | | | | | +| 9.8.6 | RTP pseudowire parameters | | | | | | +| 9.9.3 | SIP agent config data | | | | | | +| 9.9.21 | SIP agent config data 2 | | | | | | +| 9.9.14 | SIP agent performance monitoring history data | | | | | | +| 9.9.15 | SIP call initiation performance monitoring history data | | | | | | +| 9.9.19 | SIP config portal | | | | | | +| 9.9.2 | SIP user data | | | | | | +| 9.12.15 | Simple network management protocol (SNMP) configuration data | | | | | | +| 9.1.4 | Software image | M | M | | M | M | +| 9.7.25 | TC adaptor performance monitoring history data xDSL | | | | | | +| 9.2.2 | T-CONT | M | M | | M | M | +| 9.4.3 | TCP/UDP config data | | | | | | +| 9.4.4 | TCP/UDP performance monitoring history data | | | | | | +| 9.12.6 | Threshold data 1 | | | | | | +| 9.12.7 | Threshold data 2 | | | | | | +| 9.12.17 | Threshold data 64 Bit | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|----------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.12.19 | Time status message | | | | | | +| 9.2.12 | Traffic descriptor | | | | | | +| 9.2.11 | Traffic scheduler | | | | | | +| 9.16.1 | TWDM/TDM System Profile managed entity | | M | | | M | +| 9.16.2 | TWDM/TDM channel managed entity | | M | | | M | +| 9.16.3 | TWDM channel PHY/LODS performance monitoring history data | | | | | | +| 9.16.4 | TWDM channel XGEM performance monitoring history data | | | | | | +| 9.16.5 | TWDM channel PLOAM performance monitoring history data part 1 | | | | | | +| 9.16.6 | TWDM channel PLOAM performance monitoring history data part 2 | | | | | | +| 9.16.7 | TWDM channel PLOAM performance monitoring history data part 3 | | | | | | +| 9.16.8 | TWDM channel tuning performance monitoring history data part 1 | | | | | | +| 9.16.9 | TWDM channel tuning performance monitoring history data part 2 | | | | | | +| 9.16.10 | TWDM channel tuning performance monitoring history data part 3 | | | | | | +| 9.16.11 | TWDM channel OMCI performance monitoring history data | | | | | | +| 9.12.1 | UNI-G | | | | | | +| 9.7.6 | VDSL2 line configuration extensions | | | | | | +| 9.7.26 | VDSL2 line configuration extensions 2 | | | | | | +| 9.7.33 | VDSL2 line configuration extensions 3 | | | | | | +| 9.7.16 | VDSL2 line inventory and status data part 1 | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|------------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.7.17 | VDSL2 line inventory and status data part 2 | | | | | | +| 9.7.18 | VDSL2 line inventory and status data part 3 | | | | | | +| 9.7.38 | VDSL2 line inventory and status data part 4 | | | | | | +| 9.7.34 | Vectoring line configuration extensions | | | | | | +| 9.7.39 | Vectoring line inventory and status data | | | | | | +| 9.5.5 | Virtual Ethernet interface point | | | | | | +| 9.3.11 | VLAN tagging filter data | | | | | | +| 9.3.12 | VLAN tagging operation configuration data | | | | | | +| 9.9.6 | Voice service profile | | | | | | +| 9.9.8 | VoIP application service profile | | | | | | +| 9.9.18 | VoIP config data | | | | | | +| 9.9.9 | VoIP feature access codes | | | | | | +| 9.9.11 | VoIP line status | | | | | | +| 9.9.5 | VoIP media profile | | | | | | +| 9.9.4 | VoIP voice CTP | | | | | | +| 9.13.9 | VP network CTP | | | | | | +| 9.13.10 | VP performance monitoring history data | | | | | | +| 9.7.7 | xDSL channel configuration profile | | | | | | +| 9.7.35 | xDSL channel configuration profile part 2 | | | | | | +| 9.7.19 | xDSL channel downstream status data | | | | | | +| 9.7.20 | xDSL channel upstream status data | | | | | | +| 9.7.11 | xDSL downstream radio frequency interference (RFI) bands profile | | | | | | +| 9.7.27 | xDSL impulse noise monitor performance monitoring history data | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|--------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.7.3 | xDSL line configuration profile part 1 | | | | | | +| 9.7.4 | xDSL line configuration profile part 2 | | | | | | +| 9.7.5 | xDSL line configuration profile part 3 | | | | | | +| 9.7.12 | xDSL line inventory and status data part 1 | | | | | | +| 9.7.13 | xDSL line inventory and status data part 2 | | | | | | +| 9.7.14 | xDSL line inventory and status data part 3 | | | | | | +| 9.7.15 | xDSL line inventory and status data part 4 | | | | | | +| 9.7.28 | xDSL line inventory and status data part 5 | | | | | | +| 9.7.29 | xDSL line inventory and status data part 6 | | | | | | +| 9.7.30 | xDSL line inventory and status data part 7 | | | | | | +| 9.7.37 | xDSL line inventory and status data part 8 | | | | | | +| 9.7.10 | xDSL PSD mask profile | | | | | | +| 9.7.8 | xDSL subcarrier masking downstream profile | | | | | | +| 9.7.9 | xDSL subcarrier masking upstream profile | | | | | | +| 9.7.23 | xDSL xTU-C channel performance monitoring history data | | | | | | +| 9.7.31 | xDSL xTU-C performance monitoring history data part 2 | | | | | | +| 9.7.21 | xDSL xTU-C performance monitoring history data part 1 | | | | | | +| 9.7.24 | xDSL xTU-R channel performance monitoring history data | | | | | | +| 9.7.22 | xDSL xTU-R performance monitoring history data | | | | | | + +**Table 8-1 – Managed entities of the OMCI** + +| Clause | Managed entity | ITU-T G.984,
ITU-T G.987,
ITU-T G.9807.1 | ITU-T
G.989 | ITU-T
G.986 | IEEE 802.3,
IEEE 802.3av | ITU-T
G.9804 | +|---------------|------------------------------------------------------------------|---------------------------------------------------------|------------------------|------------------------|-------------------------------------|-------------------------| +| 9.2.16 | XG-PON downstream management performance monitoring history data | | | | | | +| 9.2.15 | XG-PON TC performance monitoring history data | | | | | | +| 9.2.17 | XG-PON upstream management performance monitoring history data | | | | | | +| 9.7.36 | xTU data gathering configuration | | | | | | +| 9.4.6 | IP host performance monitoring history data part 2 | | | | | | +| 9.1.18 | ONU operational performance monitoring history data | | | | | | +| 9.12.20 | BBF TR-369 USP agent | | | | | | +| 9.12.21 | Synchronous Ethernet operation | | | | | | +| 9.12.22 | Precision Time Protocol | | | | | | +| 9.12.23 | Precision Time Protocol Status | | | | | | + +## 8.2 Managed entity relation diagrams + +This clause shows the relationships between MEs. Unless indicated otherwise, Figures 8.2.1-1 to 8.2.1-3 illustrate G-PON access according to [ITU-T G.984.x] and [ITU-T G.987.x]. With suitable modifications, part or all of the same models may be used by other access technologies. + +Although Figures 8.2.1-1 to 8.2.1-3 bear some resemblance to signal flows, it is important to recognize that they in fact illustrate the relationships among the entities of the management model. + +Figure 8.2-1 gives the legend of symbols used in these diagrams. The name of the managed entity, sometimes abbreviated for ease of documentation, appears in each box, with the clause in which it is defined shown in the lower right corner. + +![Legend for managed entity relation diagrams showing various entity relationships and their meanings.](f57c7b37d7a05a99618104f390089f03_img.jpg) + +The diagram illustrates various managed entity relation diagrams. Each entity is represented by a box labeled "Managed entity A" or "Managed entity B" with the code "9.xx.xx" below it. A dashed box labeled "xx PM history data" with the code "9.xx.xx" is also shown. + +- Managed entity A** (9.xx.xx) — Entity created by ONU +- Managed entity B** (9.xx.xx) — Entity created by OLT +- xx PM history data** (9.xx.xx) — A performance monitoring (PM) entity, always created by the OLT, optionally associated with an instance of threshold data 1 and 2 +- Managed entity A** (9.xx.xx) → **Managed entity B** (9.xx.xx) — Entity A has explicit pointer to entity B +- Managed entity A** (9.xx.xx) - - - - - **Managed entity B** (9.xx.xx) — Entity A has implicit ID relationship to entity B (ME IDs are equal) +- Managed entity A** (9.xx.xx) 1 → 0..X **Managed entity B** (9.xx.xx) — There can be 0..X instances of A related to B +- Managed entity A** (9.xx.xx) 1 - - - - - 1 **Managed entity B** (9.xx.xx) — There is a 1 to 1 relationship of A to B + +OR — Only one of the options is active for any one instance + +G.988(12)\_F8.2-1 + +Legend for managed entity relation diagrams showing various entity relationships and their meanings. + +**Figure 8.2-1 – Legend for managed entity relation diagrams** + +### 8.2.1 G-PON ONU common functions + +![Diagram of G-PON ONU core showing various functional blocks and their interconnections.](7f5df81190b8dc50dad2604562ae0715_img.jpg) + +The diagram illustrates the G-PON ONU core architecture, showing various functional blocks and their interconnections. The central component is the **ONU-G (9.1.1)**, which is connected to several other functional blocks: + +- Software image (9.1.4)**: Connected to ONU-G (1:1). +- ONU data (9.1.3)**: Connected to ONU-G (1:1). +- ONU3-G (9.1.15)**: Connected to ONU-G (1:1). +- ONU manufacturing data (9.1.16)**: Connected to ONU-G (1:1). +- Cardholder (9.1.5)**: Connected to ONU-G (1:1..127). +- ONU2-G (9.1.2)**: Connected to ONU-G (1:0..1). +- ONU time configuration (9.1.17)**: Connected to ONU-G (1:0..1). +- ONU operational PM history data (9.1.18)**: Connected to ONU-G (1:0..1). +- Port mapping package (9.1.8)**: Connected to ONU-G (1:0..1). +- Traffic scheduler (9.2.11)**: Connected to ONU-G (1:0..n). +- Priority queue (up) (9.2.10)**: Connected to ONU-G (1:0..n). +- Priority queue (down) (9.2.10)**: Connected to ONU-G (1:0..n). +- GEM port netwk CTP (9.2.3)**: Connected to ONU-G (1:0..n). +- Traffic descriptor (9.2.12)**: Connected to ONU-G (1:0..n). +- GEM port PM history data (9.2.6)**: Connected to ONU-G (1:0..1). +- Circuit pack (9.1.6)**: Connected to ONU-G (1:0..1). +- Equipment extension package (9.1.9)**: Connected to ONU-G (1:0..1). +- PPTP xx UNI**: Connected to ONU-G (1:0..n). +- UNI-G (9.12.1)**: Connected to ONU-G (1:0..n). +- ANI-G (9.2.1)**: Connected to ONU-G (1:0..n). +- T-CONT (9.2.2)**: Connected to ONU-G (1:0..n). + +There are also interconnections between other blocks, including an **OR** gate between the **Priority queue (up)** and **T-CONT**, and between the **Priority queue (down)** and **GEM port netwk CTP**. The **Circuit pack (9.1.6)** is shown with multiple connections, including one to the **ANI-G (9.2.1)** block. + +At the bottom center, the text "User data ME complex" is present. The diagram is labeled with the reference G.988(17)-Amd.4(22)\_F8.2.1-1. + +Diagram of G-PON ONU core showing various functional blocks and their interconnections. + +Figure 8.2.1-1 – G-PON ONU core + +![Diagram of 1+1 PON protection (G-PON) architecture. It shows a 'Working side' and a 'Protecting side' connected by a 'Protection data' block. On the working side, traffic from a 'Traffic scheduler' (9.2.11) is split via an 'OR' node to a 'T-CONT' (9.2.2) and a 'Priority queue (up)' (9.2.10). The 'T-CONT' is connected to a 'Circuit pack' (9.1.6) and also to a 'GEM port network CTP' (9.2.3) via an 'OR' node. The 'Circuit pack' is connected to an 'ANI-G' (9.2.1). The 'Protecting side' has a similar structure. A central box states: 'When protection is activated, pointers to T-CONTs and schedulers are mapped from working side to protecting side'.](77959075c823bb5169480d7b8ff82a63_img.jpg) + +Working side +Traffic scheduler 9.2.11 +OR +T-CONT 9.2.2 +Circuit pack 9.1.6 +GEM port network CTP 9.2.3 +ANI-G 9.2.1 +Priority queue (up) 9.2.10 +When protection is activated, pointers to T-CONTs and schedulers are mapped from working side to protecting side +Protection data 9.1.10 +Protected traffic +Protecting side +Traffic scheduler 9.2.11 +T-CONT 9.2.2 +Circuit pack 9.1.6 +ANI-G 9.2.1 +G.988(12)\_F8.2.1-2 + +Diagram of 1+1 PON protection (G-PON) architecture. It shows a 'Working side' and a 'Protecting side' connected by a 'Protection data' block. On the working side, traffic from a 'Traffic scheduler' (9.2.11) is split via an 'OR' node to a 'T-CONT' (9.2.2) and a 'Priority queue (up)' (9.2.10). The 'T-CONT' is connected to a 'Circuit pack' (9.1.6) and also to a 'GEM port network CTP' (9.2.3) via an 'OR' node. The 'Circuit pack' is connected to an 'ANI-G' (9.2.1). The 'Protecting side' has a similar structure. A central box states: 'When protection is activated, pointers to T-CONTs and schedulers are mapped from working side to protecting side'. + +**Figure 8.2.1-2 – 1+1 PON protection (G-PON)** + +![Diagram of 1:1 PON protection (G-PON) architecture. It shows a 'Working side' and a 'Protecting side' connected by a 'Protection data' block. On the working side, traffic from a 'Traffic scheduler' (9.2.11) is split via an 'OR' node to a 'T-CONT' (9.2.2) and a 'Priority queue (up)' (9.2.10). The 'T-CONT' is connected to a 'Circuit pack' (9.1.6) and also to a 'GEM port network CTP' (9.2.3) via an 'OR' node. The 'Protecting side' has a similar structure but includes an 'Extra traffic' input to its 'GEM port network CTP' via an 'OR' node. A central box states: 'When protection is activated, pointers to T-CONTs and schedulers are mapped from working side to protecting side'.](47a7beddcb8a1b7abdca746967e32bb4_img.jpg) + +Working side +Traffic scheduler 9.2.11 +OR +T-CONT 9.2.2 +Circuit pack 9.1.6 +GEM port network CTP 9.2.3 +ANI-G 9.2.1 +Priority queue (up) 9.2.10 +When protection is activated, pointers to T-CONTs and schedulers are mapped from working side to protecting side +Protection data 9.1.10 +Protected traffic +Protecting side +Traffic scheduler 9.2.11 +Priority queue (up) 9.2.10 +T-CONT 9.2.2 +Circuit pack 9.1.6 +GEM port network CTP 9.2.3 +ANI-G 9.2.1 +Extra traffic +G.988(12)\_F8.2.1-3 + +Diagram of 1:1 PON protection (G-PON) architecture. It shows a 'Working side' and a 'Protecting side' connected by a 'Protection data' block. On the working side, traffic from a 'Traffic scheduler' (9.2.11) is split via an 'OR' node to a 'T-CONT' (9.2.2) and a 'Priority queue (up)' (9.2.10). The 'T-CONT' is connected to a 'Circuit pack' (9.1.6) and also to a 'GEM port network CTP' (9.2.3) via an 'OR' node. The 'Protecting side' has a similar structure but includes an 'Extra traffic' input to its 'GEM port network CTP' via an 'OR' node. A central box states: 'When protection is activated, pointers to T-CONTs and schedulers are mapped from working side to protecting side'. + +**Figure 8.2.1-3 – 1:1 PON protection (G-PON)** + +### 8.2.2 Layer 2 functions + +The OMCI supports two major layer 2 traffic mapping models: "MAC bridging and IEEE 802.1p mapping". MAC bridging is described in [IEEE 802.1D] and [IEEE 802.1Q]. The bridge illustrated in Figure 8.2.2-1 has many features, and can be used to direct traffic based on a MAC address (i.e., true bridging) or on virtual local area network (VLAN) characteristics (using the VLAN filter feature). The mapping function describes the steering of traffic from one UNI-side entity to 1-8 ANI-side ports, as shown in Figure 8.2.2-2. The mapper is equivalent to a MAC bridge with VLAN filters that only operate on the priority bits of the VLAN tags. + +![Figure 8.2.2-1 – MAC bridged LAN. A complex network diagram showing various Management Entity (ME) components and their relationships. At the top, 'Extended VLAN tag op' (9.3.13) and 'VLAN tag op config data' (9.3.12) point to a central node 'Any ME to which VLAN tagging can be assigned'. This node connects to 'GEM interworking TP' (9.2.4), which in turn connects to 'GEM port network CTP' (9.2.3). 'GEM interworking TP' also connects to 'Dot1 rate limiter' (9.3.18), 'MAC bridge port config data' (9.3.4), and 'GAL Ethernet PM' (9.2.8). 'Dot1 rate limiter' connects to 'MAC bridge service profile' (9.3.1). 'MAC bridge service profile' connects to 'MAC bridge config data' (9.3.2) and 'MAC bridge port config data' (9.3.4). 'MAC bridge config data' connects to 'UNI-G' (9.12.1) and 'PPTP xx UNI' (9.3.4). 'PPTP xx UNI' connects to 'Enet frame PM, up/dn' (9.3.30-31). 'MAC bridge port config data' (9.3.4) connects to 'MAC bridge port bridge table' (9.3.8) and 'MAC bridge port filter table' (9.3.6). 'MAC bridge port bridge table' connects to 'MB port designation data' (9.3.5) and 'MB port filter pre-assign table' (9.3.7). 'MAC bridge port filter table' connects to 'VLAN tagging filter data' (9.3.11) and 'MB port ICMPv6 proc pre-assign table' (9.3.33). 'MB port designation data' connects to 'MB port PM' (9.3.9). 'Enet frame PM, up/dn' (9.3.30-31) connects to 'Enet frame extended PM' (9.3.32) via a 'Flexible association'. 'GAL Ethernet PM' (9.2.8) connects to 'GAL Ethernet profile' (9.2.7). 'MAC bridge PM' (9.3.3) connects to 'MAC bridge service profile' (9.3.1) and 'MAC bridge port config data' (9.3.4).](e151d3468319b81f042ca232c4d82e4b_img.jpg) + +Figure 8.2.2-1 – MAC bridged LAN. A complex network diagram showing various Management Entity (ME) components and their relationships. At the top, 'Extended VLAN tag op' (9.3.13) and 'VLAN tag op config data' (9.3.12) point to a central node 'Any ME to which VLAN tagging can be assigned'. This node connects to 'GEM interworking TP' (9.2.4), which in turn connects to 'GEM port network CTP' (9.2.3). 'GEM interworking TP' also connects to 'Dot1 rate limiter' (9.3.18), 'MAC bridge port config data' (9.3.4), and 'GAL Ethernet PM' (9.2.8). 'Dot1 rate limiter' connects to 'MAC bridge service profile' (9.3.1). 'MAC bridge service profile' connects to 'MAC bridge config data' (9.3.2) and 'MAC bridge port config data' (9.3.4). 'MAC bridge config data' connects to 'UNI-G' (9.12.1) and 'PPTP xx UNI' (9.3.4). 'PPTP xx UNI' connects to 'Enet frame PM, up/dn' (9.3.30-31). 'MAC bridge port config data' (9.3.4) connects to 'MAC bridge port bridge table' (9.3.8) and 'MAC bridge port filter table' (9.3.6). 'MAC bridge port bridge table' connects to 'MB port designation data' (9.3.5) and 'MB port filter pre-assign table' (9.3.7). 'MAC bridge port filter table' connects to 'VLAN tagging filter data' (9.3.11) and 'MB port ICMPv6 proc pre-assign table' (9.3.33). 'MB port designation data' connects to 'MB port PM' (9.3.9). 'Enet frame PM, up/dn' (9.3.30-31) connects to 'Enet frame extended PM' (9.3.32) via a 'Flexible association'. 'GAL Ethernet PM' (9.2.8) connects to 'GAL Ethernet profile' (9.2.7). 'MAC bridge PM' (9.3.3) connects to 'MAC bridge service profile' (9.3.1) and 'MAC bridge port config data' (9.3.4). + +Figure 8.2.2-1 – MAC bridged LAN + +NOTE – A bridge port may be associated with any IEEE 802.3 UNI, such as Ethernet or xDSL, or another IEEE 802.3 function such as an IP host config data ME. + +![Figure 8.2.2-2 – MAC bridged LAN diagram showing the relationship between various network elements and a central GEM interworking TP.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +The diagram illustrates the architecture of a MAC bridged LAN. At the center is a box labeled "GEM interworking TP 9.2.4". To its left, a box labeled "UNI-G 9.12.1" is connected via a dashed line with a "1" at each end. Above the central TP, a box labeled "802.1p mapper svc profile 9.3.10" is connected via a solid line with a "0..8" at the UNI-G end and a "1" at the TP end. Above the mapper profile, a box labeled "GAL Ethernet profile 9.2.7" is connected via a solid line with a "0..1" at the mapper profile end and a "1" at the TP end. To the right of the TP, a box labeled "GEM port network CTP 9.2.3" is connected via a solid line with a "1" at the TP end and a "0..1" at the CTP end. Above the CTP, a box labeled "GAL Ethernet PM 9.2.8" is connected via a dashed line with a "1" at the CTP end. Below the TP, a box labeled "PPTP xx UNI" is connected via a solid line with a "1" at the TP end and a "0..1" at the PPTP end. To the right of the PPTP, a box labeled "Dot1 rate limiter 9.3.18" is connected via a solid line with a "1" at the PPTP end. Above the PPTP, a box labeled "VLAN tag op config data 9.3.12" is connected via a solid line with a "1" at the TP end and a "0..1" at the config data end. Above the config data, a box labeled "Extended VLAN tag op 9.3.13" is connected via a solid line with a "1" at the config data end. A text box "Any ME to which VLAN tagging can be assigned" has arrows pointing to the "Extended VLAN tag op" and "VLAN tag op config data" boxes. A note "G.988(12)\_F8.2.2-2" is located in the bottom right corner. + +Figure 8.2.2-2 – MAC bridged LAN diagram showing the relationship between various network elements and a central GEM interworking TP. + +**Figure 8.2.2-2 – MAC bridged LAN** + +NOTE – A mapper service profile may be associated with any IEEE 802.3 UNI, such as Ethernet or xDSL, or another IEEE 802.3 function such as an IP host config data ME. + +The two basic layer 2 services can be used in various combinations to achieve different overall connectivities. There are three major functional styles of layer 2 connectivity, illustrated in Figures 8.2.2-3 to 8.2.2-5: + +- N:1 bridging, where a bridge is used to serve multiple UNI ports from a single access network interface (ANI) service; +- 1:M mapping, where a mapper is used to serve a single UNI with multiple ANI connections, based on IEEE 802.1p priorities; +- 1:P filtering, where a bridge with filters is used to serve a single UNI with multiple ANI connections, based on some VLAN information other than IEEE 802.1p priorities. + +Given these three basic possibilities, there are also four more complex combinations as well, illustrated in Figures 8.2.2-6 to 8.2.2-9. It is strongly encouraged that these applications be utilized before other, more exotic styles of usage. + +![Diagram illustrating N:1 bridging configuration. A central 'MAC bridge service profile' (9.3.1) is connected to a 'Dot1 rate limiter' (9.3.18) with a 1:0..1 relationship. It is also connected to 'MAC bridge port config data' (9.3.4) blocks with 1:N relationships. Each 'MAC bridge port config data' block is further connected to a '(Extended) VLAN tag op' (9.3.12-13) block and a 'PPTP xx UNI' block, both with 1:1 relationships. Additionally, a 'MAC bridge port config data' (9.3.4) block is connected to a 'GEM interworking TP' (9.2.4) block with a 1:1 relationship.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +G.988(12)\_F8.2.2-3 + +Diagram illustrating N:1 bridging configuration. A central 'MAC bridge service profile' (9.3.1) is connected to a 'Dot1 rate limiter' (9.3.18) with a 1:0..1 relationship. It is also connected to 'MAC bridge port config data' (9.3.4) blocks with 1:N relationships. Each 'MAC bridge port config data' block is further connected to a '(Extended) VLAN tag op' (9.3.12-13) block and a 'PPTP xx UNI' block, both with 1:1 relationships. Additionally, a 'MAC bridge port config data' (9.3.4) block is connected to a 'GEM interworking TP' (9.2.4) block with a 1:1 relationship. + +**Figure 8.2.2-3 – Illustration of N:1 bridging** + +![Diagram illustrating 1:M mapping configuration. A central '802.1p mapper service profile' (9.3.10) is connected to a 'Dot1 rate limiter' (9.3.18) with a 1:0..1 relationship. It is connected to '(Extended) VLAN tag op' (9.3.12-13) and 'PPTP xx UNI' blocks with 1:1 relationships. It is also connected to 'GEM interworking TP' (9.2.4) blocks with 1:M relationships. Each 'GEM interworking TP' block is connected to a 'GEM port network CTP' block with a 1:1 relationship.](1ab49904e6a60be337d5b75cb7cc8ab7_img.jpg) + +G.988(12)\_F8.2.2-4 + +Diagram illustrating 1:M mapping configuration. A central '802.1p mapper service profile' (9.3.10) is connected to a 'Dot1 rate limiter' (9.3.18) with a 1:0..1 relationship. It is connected to '(Extended) VLAN tag op' (9.3.12-13) and 'PPTP xx UNI' blocks with 1:1 relationships. It is also connected to 'GEM interworking TP' (9.2.4) blocks with 1:M relationships. Each 'GEM interworking TP' block is connected to a 'GEM port network CTP' block with a 1:1 relationship. + +**Figure 8.2.2-4 – Illustration of 1:M mapping** + +![Diagram illustrating 1:P filtering architecture. At the center is a 'MAC bridge service profile' (9.3.1). Above it, two 'GEM interworking TP' (9.2.4) blocks are connected via '1' multiplicity arrows. Each GEM TP is connected to a 'GEM port network CTP' above it (1:1) and a 'MAC bridge port config data' (9.3.4) block below it (1:1). The GEM TPs also have '1' multiplicity arrows pointing to the central MAC bridge service profile. The MAC bridge service profile has '1' multiplicity arrows pointing to two 'MAC bridge port config data' (9.3.4) blocks below it. These two config blocks are connected to 'VLAN tagging filter data' (9.3.11) blocks via dashed lines. The left MAC bridge port config data is also connected to a 'Dot1 rate limiter' (9.3.18) block (1:1) and an '(Extended) VLAN tag op' (9.3.12-13) block (1:1). The right MAC bridge port config data is connected to a 'PPTP xx UNI' block (1:1) and another 'VLAN tagging filter data' (9.3.11) block (1:1). The '(Extended) VLAN tag op' block has a '1' multiplicity arrow pointing to the right 'MAC bridge port config data' block. There are also 'P' and '1' multiplicity labels on the arrows between the GEM TPs and the MAC bridge service profile.](798679874d1c29f8343506a156c79d7e_img.jpg) + +Diagram illustrating 1:P filtering architecture. At the center is a 'MAC bridge service profile' (9.3.1). Above it, two 'GEM interworking TP' (9.2.4) blocks are connected via '1' multiplicity arrows. Each GEM TP is connected to a 'GEM port network CTP' above it (1:1) and a 'MAC bridge port config data' (9.3.4) block below it (1:1). The GEM TPs also have '1' multiplicity arrows pointing to the central MAC bridge service profile. The MAC bridge service profile has '1' multiplicity arrows pointing to two 'MAC bridge port config data' (9.3.4) blocks below it. These two config blocks are connected to 'VLAN tagging filter data' (9.3.11) blocks via dashed lines. The left MAC bridge port config data is also connected to a 'Dot1 rate limiter' (9.3.18) block (1:1) and an '(Extended) VLAN tag op' (9.3.12-13) block (1:1). The right MAC bridge port config data is connected to a 'PPTP xx UNI' block (1:1) and another 'VLAN tagging filter data' (9.3.11) block (1:1). The '(Extended) VLAN tag op' block has a '1' multiplicity arrow pointing to the right 'MAC bridge port config data' block. There are also 'P' and '1' multiplicity labels on the arrows between the GEM TPs and the MAC bridge service profile. + +G.988(12)\_F8.2.2-5 + +**Figure 8.2.2-5 – Illustration of 1:P filtering** + + + +![UML-like diagram illustrating the relationships between various managed entities for 1:MP map-filtering. The diagram shows a hierarchy starting from GEM port network CTPs at the top, through GEM interworking TPs, 802.1p mapper service profiles, and MAC bridge port config data, all converging towards a central MAC bridge service profile. It also includes VLAN tagging filter data, a Dot1 rate limiter, (Extended) VLAN tag operations, and a PPTP UNI at the bottom. Multiplicities (1, M, P, 0..1) and section references (e.g., 9.2.4, 9.3.1) are provided for each entity.](e8e818455bb0d1a6153299a388b94868_img.jpg) + +The diagram illustrates the 1:MP map-filtering architecture. It features multiple network stacks and shared components with the following relationships: + +- GEM port network CTP**: Top-level entities, each connected to a **GEM interworking TP** (1:1). +- GEM interworking TP (9.2.4)**: Connected to **GEM port network CTP** (1:1), **802.1p mapper service profile** (1:M), and **MAC bridge port config data** (1:1). +- 802.1p mapper service profile (9.3.10)**: Connected to **GEM interworking TP** (M:1) and **MAC bridge port config data** (1:1). It also points towards the **MAC bridge service profile**. +- MAC bridge port config data (9.3.4)**: Connected to **GEM interworking TP** (1:1), **802.1p mapper service profile** (1:1), and the central **MAC bridge service profile** (1:P). It has a dashed association with **VLAN tagging filter data**. +- VLAN tagging filter data (9.3.11)**: Associated with **MAC bridge port config data** via dashed lines. +- MAC bridge service profile (9.3.1)**: A central component connected to **MAC bridge port config data** (P:1). +- Dot1 rate limiter (9.3.18)**: Connected to the central **MAC bridge service profile** (0..1:1). +- (Extended) VLAN tag op (9.3.12-13)**: Connected to the central **MAC bridge service profile** (1:1) and a lower-level **MAC bridge port config data**. +- PPTP xx UNI**: The bottom-most entity, connected to a **MAC bridge port config data** (1:1). + +G.988(12)\_F8.2.2-7 + +UML-like diagram illustrating the relationships between various managed entities for 1:MP map-filtering. The diagram shows a hierarchy starting from GEM port network CTPs at the top, through GEM interworking TPs, 802.1p mapper service profiles, and MAC bridge port config data, all converging towards a central MAC bridge service profile. It also includes VLAN tagging filter data, a Dot1 rate limiter, (Extended) VLAN tag operations, and a PPTP UNI at the bottom. Multiplicities (1, M, P, 0..1) and section references (e.g., 9.2.4, 9.3.1) are provided for each entity. + +**Figure 8.2.2-7 – Illustration of 1:MP map-filtering** + +![Diagram illustrating N:P bridge-filtering architecture. A central MAC bridge service profile (9.3.1) is connected to two MAC bridge port config data (9.3.4) blocks via N:P relationships. Each port config block is associated with a GEM interworking TP (9.2.4) block, which in turn connects to a GEM port network CTP. Each port config block is also associated with a (Extended) VLAN tag op (9.3.12-13) block, which connects to a PPTP xx UNI block. Each port config block is also associated with a VLAN tagging filter data (9.3.11) block via a dashed line. A Dot1 rate limiter (9.3.18) block is connected to the MAC bridge service profile via a 1:0..1 relationship.](0a42e05c07941450f34e4f7117725834_img.jpg) + +``` + +graph TD + subgraph Left_Side + GEM_P_NCTP_L[GEM port network CTP] + GEM_I_TP_L[GEM interworking TP 9.2.4] + MAC_B_PCD_L[MAC bridge port config data 9.3.4] + VLAN_TFD_L[VLAN tagging filter data 9.3.11] + DOT1_RL[Dot1 rate limiter 9.3.18] + EVTO_L[(Extended) VLAN tag op 9.3.12-13] + PPTP_UNI_L[PPTP xx UNI] + end + + subgraph Right_Side + GEM_P_NCTP_R[GEM port network CTP] + GEM_I_TP_R[GEM interworking TP 9.2.4] + MAC_B_PCD_R[MAC bridge port config data 9.3.4] + VLAN_TFD_R[VLAN tagging filter data 9.3.11] + EVTO_R[(Extended) VLAN tag op 9.3.12-13] + PPTP_UNI_R[PPTP xx UNI] + end + + MBSP[MAC bridge service profile 9.3.1] + + DOT1_RL -- "1" --> MBSP + DOT1_RL -- "0..1" --> MBSP + + MAC_B_PCD_L -- "1" --> MBSP + MAC_B_PCD_R -- "1" --> MBSP + + GEM_I_TP_L -- "1" --> GEM_P_NCTP_L + GEM_I_TP_L -- "1" --> MAC_B_PCD_L + GEM_I_TP_L -- "1" --> MBSP + + GEM_I_TP_R -- "1" --> GEM_P_NCTP_R + GEM_I_TP_R -- "1" --> MAC_B_PCD_R + GEM_I_TP_R -- "1" --> MBSP + + EVTO_L -- "1" --> MAC_B_PCD_L + EVTO_L -- "1" --> PPTP_UNI_L + EVTO_L -- "1" --> MBSP + + EVTO_R -- "1" --> MAC_B_PCD_R + EVTO_R -- "1" --> PPTP_UNI_R + EVTO_R -- "1" --> MBSP + + VLAN_TFD_L -.-> MAC_B_PCD_L + VLAN_TFD_R -.-> MAC_B_PCD_R + + MAC_B_PCD_L -- "1" --> EVTO_L + MAC_B_PCD_L -- "1" --> PPTP_UNI_L + MAC_B_PCD_L -- "1" --> VLAN_TFD_L + + MAC_B_PCD_R -- "1" --> EVTO_R + MAC_B_PCD_R -- "1" --> PPTP_UNI_R + MAC_B_PCD_R -- "1" --> VLAN_TFD_R + + G.988_12_F8_2_2_8[G.988(12)_F8.2.2-8] + +``` + +Diagram illustrating N:P bridge-filtering architecture. A central MAC bridge service profile (9.3.1) is connected to two MAC bridge port config data (9.3.4) blocks via N:P relationships. Each port config block is associated with a GEM interworking TP (9.2.4) block, which in turn connects to a GEM port network CTP. Each port config block is also associated with a (Extended) VLAN tag op (9.3.12-13) block, which connects to a PPTP xx UNI block. Each port config block is also associated with a VLAN tagging filter data (9.3.11) block via a dashed line. A Dot1 rate limiter (9.3.18) block is connected to the MAC bridge service profile via a 1:0..1 relationship. + +**Figure 8.2.2-8 – Illustration of N:P bridge-filtering** + +![Diagram illustrating N:MP bridge-map-filtering architecture. The diagram shows two symmetric halves connected by a central MAC bridge service profile. Each half consists of a GEM port network CTP, a GEM interworking TP (9.2.4), an 802.1p mapper service profile (9.3.10), a MAC bridge port config data (9.3.4), a VLAN tagging filter data (9.3.11), an (Extended) VLAN tag op (9.3.12-13), and a PPTP xx UNI. Connections are labeled with multiplicities (1, M, P, N).](c1df61cc3717e878a48e530218403403_img.jpg) + +The diagram illustrates the N:MP bridge-map-filtering architecture. It features two identical halves connected at a central MAC bridge service profile (9.3.1). Each half contains the following components and connections: + +- GEM port network CTP** connects to **GEM interworking TP (9.2.4)** with a 1:1 relationship. +- GEM interworking TP (9.2.4)** connects to **802.1p mapper service profile (9.3.10)** with a 1:M relationship. +- 802.1p mapper service profile (9.3.10)** connects to **MAC bridge port config data (9.3.4)** with a 1:1 relationship. +- MAC bridge port config data (9.3.4)** connects to **VLAN tagging filter data (9.3.11)** (dashed line) and **(Extended) VLAN tag op (9.3.12-13)** (solid line), both with 1:1 relationships. +- (Extended) VLAN tag op (9.3.12-13)** connects to **PPTP xx UNI** with a 1:1 relationship. +- On the service side, **MAC bridge port config data (9.3.4)** connects to the central **MAC bridge service profile (9.3.1)** with a 1:N relationship. + +The central **MAC bridge service profile (9.3.1)** is connected to two **MAC bridge port config data (9.3.4)** blocks, each with a 1:P relationship. A reference code G.988(12)\_F8.2.2-9 is present in the bottom right. + +Diagram illustrating N:MP bridge-map-filtering architecture. The diagram shows two symmetric halves connected by a central MAC bridge service profile. Each half consists of a GEM port network CTP, a GEM interworking TP (9.2.4), an 802.1p mapper service profile (9.3.10), a MAC bridge port config data (9.3.4), a VLAN tagging filter data (9.3.11), an (Extended) VLAN tag op (9.3.12-13), and a PPTP xx UNI. Connections are labeled with multiplicities (1, M, P, N). + +**Figure 8.2.2-9 – Illustration of N:MP bridge-map-filtering** + +Figure 8.2.2-10 illustrates the use of the multicast IW TP. A bridge is used to multiplex the multiple ANI-side ports into the single (in this case) UNI-side port. It is essential to have a unicast path in parallel to the multicast path because the unicast path carries the upstream signalling that is required for control of multicast transmissions. In most scenarios, a unicast path already exists for other user communications. + +Figure 8.2.2-11 illustrates the downstream broadcast configuration. Figure 8.2.2-12 illustrates [IEEE 802.1ag] in a MAC bridge model. Figure 8.2.2-13 illustrates [IEEE 802.1ag] in an IEEE 802.1p mapper model. + +![Figure 8.2.2-10: Illustration of a multicast service. This block diagram shows the relationships between various network components for a multicast service. At the top, 'Multicast GEM IW TP' (9.2.5) is connected to 'Extended VLAN tag op (optional)' (1:1), 'MAC bridge port config data' (9.3.4) (1:n), and 'MAC bridge service profile' (9.3.1) (1). 'GEM interworking TP' (9.2.4) is connected to 'MAC bridge port config data' (9.3.4) (1:1) and 'MAC bridge service profile' (9.3.1) (1). 'MAC bridge service profile' (9.3.1) is also connected to 'MAC bridge port config data' (9.3.4) (1:2) and '(Extended) VLAN tag op' (9.3.12-13) (1). 'MAC bridge port config data' (9.3.4) is connected to 'MC subscriber config' (9.3.28) (1), 'MC subscriber monitor' (9.3.29) (dashed line), 'MC operations profile' (9.3.27) (1:n), and 'PPTP xx UNI' (1).](38cbce07f83fba6d5a7c46605bd5743f_img.jpg) + +Figure 8.2.2-10: Illustration of a multicast service. This block diagram shows the relationships between various network components for a multicast service. At the top, 'Multicast GEM IW TP' (9.2.5) is connected to 'Extended VLAN tag op (optional)' (1:1), 'MAC bridge port config data' (9.3.4) (1:n), and 'MAC bridge service profile' (9.3.1) (1). 'GEM interworking TP' (9.2.4) is connected to 'MAC bridge port config data' (9.3.4) (1:1) and 'MAC bridge service profile' (9.3.1) (1). 'MAC bridge service profile' (9.3.1) is also connected to 'MAC bridge port config data' (9.3.4) (1:2) and '(Extended) VLAN tag op' (9.3.12-13) (1). 'MAC bridge port config data' (9.3.4) is connected to 'MC subscriber config' (9.3.28) (1), 'MC subscriber monitor' (9.3.29) (dashed line), 'MC operations profile' (9.3.27) (1:n), and 'PPTP xx UNI' (1). + +**Figure 8.2.2-10 – Illustration of a multicast service** + +![Figure 8.2.2-11: Illustration of the downstream broadcast configuration. This block diagram shows the configuration for downstream broadcast. At the top, 'GEM port network CTP' is connected to 'GEM IW TP (Note)' (9.2.4) (1:1). 'GEM IW TP (Note)' is connected to two 'MAC bridge port config data' (9.3.4) blocks (1:n). Each 'MAC bridge port config data' block is connected to a 'VLAN tagging filter data' (9.3.11) block (dashed line) and a 'MAC bridge service profile' (9.3.1) block (1:M).](ec3647789b5c38fb686f2a0833324e79_img.jpg) + +Figure 8.2.2-11: Illustration of the downstream broadcast configuration. This block diagram shows the configuration for downstream broadcast. At the top, 'GEM port network CTP' is connected to 'GEM IW TP (Note)' (9.2.4) (1:1). 'GEM IW TP (Note)' is connected to two 'MAC bridge port config data' (9.3.4) blocks (1:n). Each 'MAC bridge port config data' block is connected to a 'VLAN tagging filter data' (9.3.11) block (dashed line) and a 'MAC bridge service profile' (9.3.1) block (1:M). + +**Figure 8.2.2-11 – Illustration of the downstream broadcast configuration** + +NOTE – IW option set to downstream broadcast. + +![Figure 8.2.2-12: Illustration of [IEEE 802.1ag] in a MAC bridge model. This is a class diagram showing the relationships between various network entities. At the center is 'Dotlag MEP' (9.3.22). It has a 1-to-M association with 'MAC bridge port config data' (9.3.4), which in turn has a 1-to-M association with 'MAC bridge service profile' (9.3.1). 'Dotlag MEP' also has a 1-to-0..p association with 'Dotlag maintenance assoc' (9.3.20), which has a 1-to-M association with 'Dotlag maintenance domain' (9.3.19). 'Dotlag MEP' is also associated with 'Dotlag MEP status' (9.3.23) and 'Dotlag MEP CCM database' (9.3.24) via dashed lines. 'MAC bridge service profile' (9.3.1) has a 0..1 association with 'Dotlag CFM stack' (9.3.25). 'Dotlag CFM stack' (9.3.25) is associated with 'Dotlag default MD level' (9.3.21) via a dashed line. 'Dotlag default MD level' (9.3.21) is associated with 'Dotlag chassis mgt info' (9.3.26) via a dashed line. The diagram is labeled G.988(12)_F8.2.2-12.](12c19090355e19922e23044633b9d1ea_img.jpg) + +Figure 8.2.2-12: Illustration of [IEEE 802.1ag] in a MAC bridge model. This is a class diagram showing the relationships between various network entities. At the center is 'Dotlag MEP' (9.3.22). It has a 1-to-M association with 'MAC bridge port config data' (9.3.4), which in turn has a 1-to-M association with 'MAC bridge service profile' (9.3.1). 'Dotlag MEP' also has a 1-to-0..p association with 'Dotlag maintenance assoc' (9.3.20), which has a 1-to-M association with 'Dotlag maintenance domain' (9.3.19). 'Dotlag MEP' is also associated with 'Dotlag MEP status' (9.3.23) and 'Dotlag MEP CCM database' (9.3.24) via dashed lines. 'MAC bridge service profile' (9.3.1) has a 0..1 association with 'Dotlag CFM stack' (9.3.25). 'Dotlag CFM stack' (9.3.25) is associated with 'Dotlag default MD level' (9.3.21) via a dashed line. 'Dotlag default MD level' (9.3.21) is associated with 'Dotlag chassis mgt info' (9.3.26) via a dashed line. The diagram is labeled G.988(12)\_F8.2.2-12. + +**Figure 8.2.2-12 – Illustration of [IEEE 802.1ag] in a MAC bridge model** + +![Figure 8.2.2-13: Illustration of [IEEE 802.1ag] in an IEEE 802.1p mapper model. This class diagram is similar to Figure 8.2.2-12 but replaces 'MAC bridge service profile' (9.3.1) with '802.1p mapper service profile' (9.3.10). 'Dotlag MEP' (9.3.22) has a 1-to-M association with '802.1p mapper service profile' (9.3.10). '802.1p mapper service profile' (9.3.10) has a 0..1 association with 'Dotlag CFM stack' (9.3.25). 'Dotlag CFM stack' (9.3.25) is associated with 'Dotlag default MD level' (9.3.21) via a dashed line. 'Dotlag default MD level' (9.3.21) is associated with 'Dotlag chassis mgt info' (9.3.26) via a dashed line. All other relationships remain the same as in Figure 8.2.2-12. The diagram is labeled G.988(12)_F8.2.2-13.](01e00200a536673d6cd0e6d8705047a0_img.jpg) + +Figure 8.2.2-13: Illustration of [IEEE 802.1ag] in an IEEE 802.1p mapper model. This class diagram is similar to Figure 8.2.2-12 but replaces 'MAC bridge service profile' (9.3.1) with '802.1p mapper service profile' (9.3.10). 'Dotlag MEP' (9.3.22) has a 1-to-M association with '802.1p mapper service profile' (9.3.10). '802.1p mapper service profile' (9.3.10) has a 0..1 association with 'Dotlag CFM stack' (9.3.25). 'Dotlag CFM stack' (9.3.25) is associated with 'Dotlag default MD level' (9.3.21) via a dashed line. 'Dotlag default MD level' (9.3.21) is associated with 'Dotlag chassis mgt info' (9.3.26) via a dashed line. All other relationships remain the same as in Figure 8.2.2-12. The diagram is labeled G.988(12)\_F8.2.2-13. + +**Figure 8.2.2-13 – Illustration of [IEEE 802.1ag] in an IEEE 802.1p mapper model** + +NOTE – If a mapper is associated with the ports of a bridge, the 802.1ag entities should be associated with the bridge and its ports, rather than with the mapper. + +### 8.2.3 This clause is intentionally left blank + +### 8.2.4 xDSL service + +See Figures 8.2.4-1 and Figure 8.2.4-2 for ME relation diagrams addressing ADSL (ITU-T G.992 family) and VDSL (ITU-T G.993 family) services. + +![ME relation diagram for xDSL (ADSL and VDSL) services. The diagram shows the relationships between various Management Entities (MEs) for xDSL services. At the center is the PPTP xDSL UNI 1 (9.7.1) ME. Above it, 'From layer 2 ME (802.1p or MAC bridge port configuration data) or VP network CTP' connects to UNI 1 with a 0..256 relationship. UNI 1 connects to 'xDSL subcarrier mask up' (9.7.9) with 0..1 and 1 relationships, and to 'xDSL subcarrier mask dn' (9.7.8) with 1 and 1 relationships. UNI 1 connects to 'xDSL line config profile part 1-3' (9.7.3-5) with 0..1 and 1 relationships. UNI 1 connects to 'VDSL2 line config ext 2-3' (9.7.6, 26, 33) with a dashed line. UNI 1 connects to 'Vectoring line config ext and xTU data gath config' (9.7.34, 36) with a dashed line. UNI 1 connects to 'xDSL line inv and status 1-8' (9.7.12-15, 28-30, 37) with a dashed line. UNI 1 connects to 'VDSL2 line inv and status 1-4' (9.7.16-18, 38) with a dashed line. UNI 1 connects to 'Vectoring line inventory and status' (9.7.39) with a dashed line. UNI 1 connects to 'Data gathering line test, diag and status' (9.7.40) with a dashed line. UNI 1 connects to 'UNI-G' (9.12.1) with a dashed line. UNI 1 connects to 'xTU-R PM history' (9.7.22) with a dashed line. UNI 1 connects to 'xTU-C PM history, part 1 and 2' (9.7.21, 31) with a dashed line. UNI 1 connects to 'PTM PM history' (9.7.32) with a dashed line. UNI 1 connects to 'Impulse noise PM' (9.7.27) with a dashed line. UNI 1 connects to 'TC adaptor PM history xDSL' (9.7.25) with a dashed line. UNI 1 connects to 'xDSL down RFI bands profile' (9.7.11) with 0..1 and 1 relationships. UNI 1 connects to 'xDSL PSD mask' (9.7.10) with 0..1 and 1 relationships. UNI 1 connects to 'xDSL channel config profile 2' (9.7.35) with 1 and 1 relationships. UNI 1 connects to 'xDSL channel config profile' (9.7.7) with 1 and 1 relationships. UNI 1 connects to 'xDSL channel upstream and downstream status' (9.7.19-20) with a dashed line. UNI 1 connects to 'xTU-C/R channel PM' (9.7.23-24) with a dashed line. UNI 1 connects to 'PPTP xDSL UNI 2' (9.7.2) with 1 and 8 relationships. UNI 2 connects to 'xDSL channel config profile' (9.7.7) with 0..1 and 8 relationships. UNI 2 connects to 'xDSL channel upstream and downstream status' (9.7.19-20) with a dashed line. UNI 2 connects to 'xTU-C/R channel PM' (9.7.23-24) with a dashed line.](5ee1bbbf85b473f78af9ec8368a4159a_img.jpg) + +``` + +graph TD + L2ME["From layer 2 ME (802.1p or +MAC bridge port configuration +data) or VP network CTP"] -- "0..256" --> UNI1 + UNI1["PPTP xDSL +UNI 1 +9.7.1"] -- "1" --- "0..1" --> USM_UP["xDSL subcarrier +mask up +9.7.9"] + UNI1 -- "1" --- "0..1" --> USM_DN["xDSL xDSL subcarrier +mask dn +9.7.8"] + UNI1 -- "1" --- "0..1" --> LCP13["xDSL line config +profile part 1-3 +9.7.3-5"] + UNI1 -- "1" --- "0..1" --> PSD["xDSL PSD +mask +9.7.10"] + UNI1 -- "1" --- "0..1" --> RFI["xDSL down +RFI bands +profile +9.7.11"] + UNI1 -- "1" --- "1" --> CCP2["xDSL channel +config profile 2 +9.7.35"] + UNI1 -- "1" --- "1" --> CCP["xDSL channel +config profile +9.7.7"] + UNI1 -- "1" --- "8" --> UNI2["PPTP xDSL +UNI 2 +9.7.2"] + UNI2 -- "8" --- "0..1" --> CCP + + UNI1 -.- VDSL2_LCE["VDSL2 line config +ext 2-3 +9.7.6, 26, 33"] + UNI1 -.- VECT_LCE["Vectoring line config +ext and xTU data gath +config +9.7.34, 36"] + UNI1 -.- XDSL_LIS["xDSL line inv and +status 1-8 +9.7.12-15, 28-30, 37"] + UNI1 -.- VDSL2_LIS["VDSL2 line inv and +status 1-4 +9.7.16-18, 38"] + UNI1 -.- VECT_LIS["Vectoring line +inventory and status +9.7.39"] + UNI1 -.- DATA_GATH["Data gathering line +test, diag and status +9.7.40"] + UNI1 -.- UNIG["UNI-G +9.12.1"] + UNI1 -.- XTUR_PM["xTU-R PM +history +9.7.22"] + UNI1 -.- XTUC_PM["xTU-C PM +history, part +1 and 2 +9.7.21, 31"] + UNI1 -.- PTM_PM["PTM PM +history +9.7.32"] + UNI1 -.- IMP_PM["Impulse +noise PM +9.7.27"] + UNI1 -.- TC_PM["TC adaptor +PM history +xDSL +9.7.25"] + + UNI2 -.- CH_STAT["xDSL channel +upstream and +downstream +status +9.7.19-20"] + UNI2 -.- CH_PM["xTU-C/R +channel +PM +9.7.23-24"] + UNI1 -.- CH_STAT + UNI1 -.- CH_PM + +``` + +ME relation diagram for xDSL (ADSL and VDSL) services. The diagram shows the relationships between various Management Entities (MEs) for xDSL services. At the center is the PPTP xDSL UNI 1 (9.7.1) ME. Above it, 'From layer 2 ME (802.1p or MAC bridge port configuration data) or VP network CTP' connects to UNI 1 with a 0..256 relationship. UNI 1 connects to 'xDSL subcarrier mask up' (9.7.9) with 0..1 and 1 relationships, and to 'xDSL subcarrier mask dn' (9.7.8) with 1 and 1 relationships. UNI 1 connects to 'xDSL line config profile part 1-3' (9.7.3-5) with 0..1 and 1 relationships. UNI 1 connects to 'VDSL2 line config ext 2-3' (9.7.6, 26, 33) with a dashed line. UNI 1 connects to 'Vectoring line config ext and xTU data gath config' (9.7.34, 36) with a dashed line. UNI 1 connects to 'xDSL line inv and status 1-8' (9.7.12-15, 28-30, 37) with a dashed line. UNI 1 connects to 'VDSL2 line inv and status 1-4' (9.7.16-18, 38) with a dashed line. UNI 1 connects to 'Vectoring line inventory and status' (9.7.39) with a dashed line. UNI 1 connects to 'Data gathering line test, diag and status' (9.7.40) with a dashed line. UNI 1 connects to 'UNI-G' (9.12.1) with a dashed line. UNI 1 connects to 'xTU-R PM history' (9.7.22) with a dashed line. UNI 1 connects to 'xTU-C PM history, part 1 and 2' (9.7.21, 31) with a dashed line. UNI 1 connects to 'PTM PM history' (9.7.32) with a dashed line. UNI 1 connects to 'Impulse noise PM' (9.7.27) with a dashed line. UNI 1 connects to 'TC adaptor PM history xDSL' (9.7.25) with a dashed line. UNI 1 connects to 'xDSL down RFI bands profile' (9.7.11) with 0..1 and 1 relationships. UNI 1 connects to 'xDSL PSD mask' (9.7.10) with 0..1 and 1 relationships. UNI 1 connects to 'xDSL channel config profile 2' (9.7.35) with 1 and 1 relationships. UNI 1 connects to 'xDSL channel config profile' (9.7.7) with 1 and 1 relationships. UNI 1 connects to 'xDSL channel upstream and downstream status' (9.7.19-20) with a dashed line. UNI 1 connects to 'xTU-C/R channel PM' (9.7.23-24) with a dashed line. UNI 1 connects to 'PPTP xDSL UNI 2' (9.7.2) with 1 and 8 relationships. UNI 2 connects to 'xDSL channel config profile' (9.7.7) with 0..1 and 8 relationships. UNI 2 connects to 'xDSL channel upstream and downstream status' (9.7.19-20) with a dashed line. UNI 2 connects to 'xTU-C/R channel PM' (9.7.23-24) with a dashed line. + +G.988(22)\_F8.2.4-1 + +**Figure 8.2.4-1 – ME relation diagram for xDSL (ADSL and VDSL) services** + +![ATM interworking for xDSL (ADSL and VDSL) diagram. The diagram shows the relationships between various Management Entities (MEs) for ATM interworking. At the center is the 'Interworking VCC TP' (9.13.4) ME. Above it, 'From layer 2 ME (802.1p mapper or MAC bridge port configuration data)' connects to the central ME with a 0..1 relationship. The central ME connects to 'AAL5 profile' (9.13.5) with 0..n and 1 relationships. The central ME connects to 'VP network CTP' (9.13.9) with 0..n and 1 relationships. The central ME connects to 'AAL5 PM history data' (9.13.6) with a dashed line. The central ME connects to 'PPTP xDSL UNI part 1 (Note)' with 1 and 0..4 relationships. The 'VP network CTP' (9.13.9) ME connects to 'VP PM history data' (9.13.10) with a dashed line.](3442f31a562d1ef45bfa18b18a6a1ddc_img.jpg) + +``` + +graph TD + L2ME_ATM["From layer 2 ME (802.1p +mapper or MAC bridge +port configuration data)"] -- "0..1" --- "1" --> IW_VCC["Interworking +VCC TP +9.13.4"] + IW_VCC -- "1" --- "0..n" --> AAL5_PROF["AAL5 +profile +9.13.5"] + IW_VCC -- "1" --- "0..n" --> VP_CTP["VP network +CTP +9.13.9"] + IW_VCC -- "1" --- "0..4" --> PPTP_UNI["PPTP xDSL UNI part 1 +(Note)"] + IW_VCC -.- AAL5_PM["AAL5 PM +history data +9.13.6"] + VP_CTP -.- VP_PM["VP PM +history data +9.13.10"] + +``` + +ATM interworking for xDSL (ADSL and VDSL) diagram. The diagram shows the relationships between various Management Entities (MEs) for ATM interworking. At the center is the 'Interworking VCC TP' (9.13.4) ME. Above it, 'From layer 2 ME (802.1p mapper or MAC bridge port configuration data)' connects to the central ME with a 0..1 relationship. The central ME connects to 'AAL5 profile' (9.13.5) with 0..n and 1 relationships. The central ME connects to 'VP network CTP' (9.13.9) with 0..n and 1 relationships. The central ME connects to 'AAL5 PM history data' (9.13.6) with a dashed line. The central ME connects to 'PPTP xDSL UNI part 1 (Note)' with 1 and 0..4 relationships. The 'VP network CTP' (9.13.9) ME connects to 'VP PM history data' (9.13.10) with a dashed line. + +G.988(12)\_F8.2.4-2 + +NOTE – Individual bearer channels accessible via two MSBs of PTP ME ID. + +**Figure 8.2.4-2 – ATM interworking for xDSL (ADSL and VDSL)** + +The ME relation diagram addressing G.fast (FAST, [ITU-T G.9701]) service is shown in Figure 8.2.4-3. + +![ME relations diagram for G.fast (FAST) service. The diagram shows a central PTP xDSL UNI 3(FAST) (9.7.48) connected to a UNI-G (9.12.1) and a PTP xDSL UNI 1 (9.7.1). The UNI-G is connected to a layer 2 ME (802.1p or MAC bridge port configuration data). The PTP xDSL UNI 1 is connected to a FAST line inventory and status, part 1 and 2 (9.7.56-57). The PTP xDSL UNI 3(FAST) is connected to a FAST line config profile 1-4 (9.7.49-52), a FAST vectoring line config extension (9.7.55), a FAST data path config profile (9.7.54), and a FAST channel config profile upstream/downstream (9.7.53 and 9.7.53.1). The FAST channel config profile is connected to a FAST FTU-O PM history data (9.7.58) and a FAST FTU-R PM history data (9.7.59). The FAST line inventory and status is connected to a FAST line failures PM history data (9.7.60). The diagram is labeled G.988(22)_F8.2.4-3.](dbd074feb5cce1300f42f91da8f673d1_img.jpg) + +ME relations diagram for G.fast (FAST) service. The diagram shows a central PTP xDSL UNI 3(FAST) (9.7.48) connected to a UNI-G (9.12.1) and a PTP xDSL UNI 1 (9.7.1). The UNI-G is connected to a layer 2 ME (802.1p or MAC bridge port configuration data). The PTP xDSL UNI 1 is connected to a FAST line inventory and status, part 1 and 2 (9.7.56-57). The PTP xDSL UNI 3(FAST) is connected to a FAST line config profile 1-4 (9.7.49-52), a FAST vectoring line config extension (9.7.55), a FAST data path config profile (9.7.54), and a FAST channel config profile upstream/downstream (9.7.53 and 9.7.53.1). The FAST channel config profile is connected to a FAST FTU-O PM history data (9.7.58) and a FAST FTU-R PM history data (9.7.59). The FAST line inventory and status is connected to a FAST line failures PM history data (9.7.60). The diagram is labeled G.988(22)\_F8.2.4-3. + +Figure 8.2.4-3 – ME relations diagram for G.fast (FAST) service + +8.2.5 This clause is intentionally left blank + +### 8.2.6 MoCA service + +See Figure 8.2.6-1. + +![Multimedia over Coax Alliance diagram. The diagram shows a central PTP MoCA UNI (9.10.1) connected to a MoCA interface PM (9.10.3), a MoCA Ethernet PM (9.10.2), and a UNI-G (9.12.1). The PTP MoCA UNI is connected to a layer 2 ME (802.1p mapper or MAC bridge port configuration data). The diagram is labeled G.988(12)_F8.2.6-1.](036c200da9b64c3eb5aae2d67bb53e1f_img.jpg) + +Multimedia over Coax Alliance diagram. The diagram shows a central PTP MoCA UNI (9.10.1) connected to a MoCA interface PM (9.10.3), a MoCA Ethernet PM (9.10.2), and a UNI-G (9.12.1). The PTP MoCA UNI is connected to a layer 2 ME (802.1p mapper or MAC bridge port configuration data). The diagram is labeled G.988(12)\_F8.2.6-1. + +Figure 8.2.6-1 – Multimedia over Coax Alliance + +8.2.7 This clause is intentionally left blank + +### 8.2.8 VoIP service + +See Figures 8.2.8-1 to 8.2.8-6. + +![Diagram of IP-path managed SIP VoIP Management Entities (MEs)](2580688a4de0a29692805cc6ba4822d7_img.jpg) + +This diagram illustrates the Management Entity (ME) relationships for IP-path managed SIP VoIP. It is divided into two columns: **Global MEs** and **Per-UNI MEs**. + +- Global MEs:** + - VoIP config data (9.9.18) + - SIP config portal (9.9.19) + - SIP agent PM history (9.9.14) + - SIP call initiation PM (9.9.15) +- Per-UNI MEs:** + - PPTP POTS UNI (9.9.1) + - UNI-G (9.12.1) + - Call ctrl PM history (9.9.12) +- Central MEs:** + - VoIP line status (9.9.11) + - RTP PM history data (9.9.13) + +Dashed lines connect the Global MEs and Per-UNI MEs to the central VoIP line status and RTP PM history data MEs. A reference code G.988(12)\_F8.2.8-1 is shown at the bottom right. + +Diagram of IP-path managed SIP VoIP Management Entities (MEs) + +NOTE – MEs that require long character strings point to large string MEs. MEs that require a network address point to network address MEs. + +**Figure 8.2.8-1 – IP-path managed SIP VoIP** + +![Diagram of IP path managed ITU-T H.248 VoIP Management Entities (MEs)](40a8c30f7ea5ecea4912e040c97c5b9c_img.jpg) + +This diagram illustrates the Management Entity (ME) relationships for IP path managed ITU-T H.248 VoIP. It is divided into two columns: **Global MEs** and **Per-UNI MEs**. + +- Global MEs:** + - VoIP config data (9.9.18) + - MGC PM history (9.9.17) + - MGC config portal (9.9.20) +- Per-UNI MEs:** + - PPTP POTS UNI (9.9.1) + - UNI-G (9.12.1) + - Call ctrl PM history (9.9.12) +- Central MEs:** + - VoIP line status (9.9.11) + - RTP PM history data (9.9.13) + +Dashed lines connect the Global MEs and Per-UNI MEs to the central VoIP line status and RTP PM history data MEs. A reference code G.988(12)\_F8.2.8-2 is shown at the bottom right. + +Diagram of IP path managed ITU-T H.248 VoIP Management Entities (MEs) + +NOTE – MEs that require long character strings point to large string MEs. MEs that require a network address point to network address MEs. + +**Figure 8.2.8-2 – IP path managed ITU-T H.248 VoIP** + +![Figure 8.2.8-3 – OMCI managed SIP VoIP. This is a class diagram showing the relationships between various Management Entity (ME) objects. The central object is 'SIP user data' (9.9.2). It has a 1-to-0..m relationship with 'VoIP voice CTP' (9.9.4) and a 1-to-1 relationship with 'PPTP POTS UNI' (9.9.1). 'VoIP voice CTP' has a 1-to-0..m relationship with 'VoIP config data' (9.9.18) and a 1-to-1 relationship with 'VoIP media profile' (9.9.5). 'VoIP media profile' has a 1-to-1 relationship with 'Voice service profile' (9.9.6) and a 1-to-0..m relationship with 'RTP profile data' (9.9.7). 'SIP user data' also has a 1-to-0..m relationship with 'Network dial plan table' (9.9.10), a 1-to-0..m relationship with 'VoIP feature access codes' (9.9.9), a 1-to-1 relationship with 'Authentication security method' (9.12.4), and a 1-to-0..m relationship with 'VoIP appl service profile' (9.9.8). 'SIP agent config data' (9.9.3) has a 1-to-1 relationship with 'TCP/UDP config data' (9.4.3). 'SIP call initiation PM' (9.9.15) is associated with 'SIP user data'. 'RTP PM history data' (9.9.13), 'Call ctrl PM history' (9.9.12), and 'UNI-G' (9.12.1) are associated with 'PPTP POTS UNI'. 'SIP agent PM history data' (9.9.14) is associated with 'SIP agent config data'. The diagram is labeled G.988(12)_F8.2.8-3.](4162c218fc7881cd90fc9574e07d2327_img.jpg) + +Figure 8.2.8-3 – OMCI managed SIP VoIP. This is a class diagram showing the relationships between various Management Entity (ME) objects. The central object is 'SIP user data' (9.9.2). It has a 1-to-0..m relationship with 'VoIP voice CTP' (9.9.4) and a 1-to-1 relationship with 'PPTP POTS UNI' (9.9.1). 'VoIP voice CTP' has a 1-to-0..m relationship with 'VoIP config data' (9.9.18) and a 1-to-1 relationship with 'VoIP media profile' (9.9.5). 'VoIP media profile' has a 1-to-1 relationship with 'Voice service profile' (9.9.6) and a 1-to-0..m relationship with 'RTP profile data' (9.9.7). 'SIP user data' also has a 1-to-0..m relationship with 'Network dial plan table' (9.9.10), a 1-to-0..m relationship with 'VoIP feature access codes' (9.9.9), a 1-to-1 relationship with 'Authentication security method' (9.12.4), and a 1-to-0..m relationship with 'VoIP appl service profile' (9.9.8). 'SIP agent config data' (9.9.3) has a 1-to-1 relationship with 'TCP/UDP config data' (9.4.3). 'SIP call initiation PM' (9.9.15) is associated with 'SIP user data'. 'RTP PM history data' (9.9.13), 'Call ctrl PM history' (9.9.12), and 'UNI-G' (9.12.1) are associated with 'PPTP POTS UNI'. 'SIP agent PM history data' (9.9.14) is associated with 'SIP agent config data'. The diagram is labeled G.988(12)\_F8.2.8-3. + +NOTE – MEs that require long character strings point to large string MEs. MEs that require a network address point to network address MEs. + +**Figure 8.2.8-3 – OMCI managed SIP VoIP** + +![Figure 8.2.8-4 – OMCI managed ITU-T H.248 VoIP. This class diagram shows the relationships between various Management Entity (ME) objects. The central object is 'MGC config data' (9.9.16). It has a 1-to-0..1 relationship with 'TCP/UDP config data' (9.4.3) and a 1-to-1 relationship with 'PPTP POTS UNI' (9.9.1). 'PPTP POTS UNI' has a 1-to-0..1 relationship with 'VoIP voice CTP' (9.9.4). 'VoIP voice CTP' has a 1-to-0..m relationship with 'VoIP config data' (9.9.18) and a 1-to-1 relationship with 'VoIP media profile' (9.9.5). 'VoIP media profile' has a 1-to-1 relationship with 'Voice service profile' (9.9.6) and a 1-to-0..m relationship with 'RTP profile data' (9.9.7). 'MGC config data' is also associated with 'MGC PM history data' (9.9.17). 'RTP PM history data' (9.9.13), 'Call control PM' (9.9.12), and 'UNI-G' (9.12.1) are associated with 'PPTP POTS UNI'. The diagram is labeled G.988(12)_F8.2.8-4.](a0e8fe7862a6d7341faf5dac275277cc_img.jpg) + +Figure 8.2.8-4 – OMCI managed ITU-T H.248 VoIP. This class diagram shows the relationships between various Management Entity (ME) objects. The central object is 'MGC config data' (9.9.16). It has a 1-to-0..1 relationship with 'TCP/UDP config data' (9.4.3) and a 1-to-1 relationship with 'PPTP POTS UNI' (9.9.1). 'PPTP POTS UNI' has a 1-to-0..1 relationship with 'VoIP voice CTP' (9.9.4). 'VoIP voice CTP' has a 1-to-0..m relationship with 'VoIP config data' (9.9.18) and a 1-to-1 relationship with 'VoIP media profile' (9.9.5). 'VoIP media profile' has a 1-to-1 relationship with 'Voice service profile' (9.9.6) and a 1-to-0..m relationship with 'RTP profile data' (9.9.7). 'MGC config data' is also associated with 'MGC PM history data' (9.9.17). 'RTP PM history data' (9.9.13), 'Call control PM' (9.9.12), and 'UNI-G' (9.12.1) are associated with 'PPTP POTS UNI'. The diagram is labeled G.988(12)\_F8.2.8-4. + +NOTE – MEs that require long character strings point to large string MEs. MEs that require a network address point to network address MEs. + +**Figure 8.2.8-4 – OMCI managed ITU-T H.248 VoIP** + +![Diagram of Common IP services showing relationships between network address, authentication, and IP host configuration MEs.](701bc79e78b382bcfd3ba85597dbb9c3_img.jpg) + +``` + +graph TD + Input1[Any ME that requires +a network address] --> NA[Network address +9.12.3] + NA --- LS[Large string +9.12.5] + NA --- ASM[Authentication +security +method +9.12.4] + + Input2[From layer 2 ME (802.1p +mapper or MAC bridge +port configuration data)] -->|0..1| IP[IP or IPv6 +host config +data +9.4.1, 9.4.5] + IP ---|0..m| PM[IP host PM +history data +9.4.2] + IP ---|0..m| TCP[TCP/UDP +config data +9.4.3] + +``` + +G.988(12)\_F8.2.8-5 + +Diagram of Common IP services showing relationships between network address, authentication, and IP host configuration MEs. + +**Figure 8.2.8-5 – Common IP services** + +![Diagram of VoIP connectivity showing the relationship between GEM, MAC bridge, IP host, TCP/UDP, SIP, and POTS MEs.](640d28a694bbdbaf9b11a3bfdcc800fc_img.jpg) + +``` + +graph TD + GEM_CTP[GEM port +network +CTP +9.2.3] -->|0..m| GEM_TP[GEM +interworking +TP +9.2.4] + GEM_TP -->|0..1| MAC_B[MAC bridge +port config +data +9.3.4] + MAC_B -->|0..m| MAC_S[MAC bridge +service +profile +9.3.1] + MAC_S -->|0..p| MAC_B2[MAC bridge +port config +data +9.3.4] + MAC_B2 -->|1| EVLAN[Ext VLAN +tagging op +9.3.13] + + MAC_B2 -->|0..1| IP_H[IP or IPv6 +host config +data +9.4.1, 9.4.5] + IP_H -->|0..m| TCP_C[TCP/UDP +config data +9.4.3] + TCP_C -->|0..1| SIP_A[SIP agent +config data +9.9.3] + SIP_A -->|0..m| SIP_U[SIP user data +9.9.2] + SIP_U -->|0..1| VOIP[VoIP voice +CTP +9.9.4] + VOIP -->|0..1| POTS[PPTP POTS +UNI +9.9.1] + + SIP_U -->|0..1| POTS + +``` + +G.988(12)\_F8.2.8-6 + +Diagram of VoIP connectivity showing the relationship between GEM, MAC bridge, IP host, TCP/UDP, SIP, and POTS MEs. + +NOTE – ITU-T H.248 connectivity is very similar to this SIP example. + +**Figure 8.2.8-6 – VoIP connectivity** + +### 8.2.9 Pseudowire service + +See Figures 8.2.9-1 to 8.2.9-3. + +![Figure 8.2.9-1 – Time division multiplex pseudowire. This is a functional block diagram showing the architecture of a Time Division Multiplex (TDM) pseudowire. At the bottom, a 'Logical N x 64 kbit/s CTP' (9.8.2) connects to a 'PPTP CES UNI' (9.8.1) via a 'Structured' path. The 'PPTP CES UNI' also connects to a 'UNI-G' (9.12.1) via an 'Unstructured' path. The 'PPTP CES UNI' is associated with 'CES phy PM 1, 2, 3' (9.8.4, -12-13). Above the 'PPTP CES UNI' is a 'Pseudowire termination point' (9.8.5), which is connected to the 'PPTP CES UNI' and to a 'Pseudowire maintenance profile' (9.8.7). The 'Pseudowire termination point' is also connected to an 'OR' node labeled 'Over IP'. This 'OR' node is connected to 'TCP/UDP config data' (9.4.3) and to another 'OR' node labeled 'Over MPLS'. The 'Over MPLS' node is connected to 'MPLS PW TP' (9.8.14), which in turn is connected to '(Extended) VLAN tag op' (9.3.12-13) and to a third 'OR' node. This third 'OR' node is connected to 'CES service profile' (9.8.3), 'TCP/UDP config data' (9.4.3), and to 'GEM IW TP' (9.2.4). The 'GEM IW TP' is connected to 'GEM port network CTP' and receives data 'From layer 2 ME (802.1p mapper or MAC bridge port configuration data)'. The 'Over IP' node is also connected to 'Pseudowire termination point' (9.8.5), 'RTP pseudowire parms' (9.8.6), and to an 'OR' node labeled 'Over Ethernet'. The 'Over Ethernet' node is connected to 'Ethernet flow TP' (9.8.9), which is also connected to 'GEM IW TP' (9.2.4). Dashed lines connect 'Pseudowire PM history data' (9.8.8) to the 'Pseudowire termination point' and 'PPTP CES UNI', and 'CES phy PM 1, 2, 3' (9.8.4, -12-13) to the 'PPTP CES UNI'. Multiplicity indicators (1, N, 1..n, 0..1) are shown on the connections. The diagram is labeled G.988(12)_F8.2.9-1 at the bottom right.](89f8aefc01866631793087542316cef2_img.jpg) + +Figure 8.2.9-1 – Time division multiplex pseudowire. This is a functional block diagram showing the architecture of a Time Division Multiplex (TDM) pseudowire. At the bottom, a 'Logical N x 64 kbit/s CTP' (9.8.2) connects to a 'PPTP CES UNI' (9.8.1) via a 'Structured' path. The 'PPTP CES UNI' also connects to a 'UNI-G' (9.12.1) via an 'Unstructured' path. The 'PPTP CES UNI' is associated with 'CES phy PM 1, 2, 3' (9.8.4, -12-13). Above the 'PPTP CES UNI' is a 'Pseudowire termination point' (9.8.5), which is connected to the 'PPTP CES UNI' and to a 'Pseudowire maintenance profile' (9.8.7). The 'Pseudowire termination point' is also connected to an 'OR' node labeled 'Over IP'. This 'OR' node is connected to 'TCP/UDP config data' (9.4.3) and to another 'OR' node labeled 'Over MPLS'. The 'Over MPLS' node is connected to 'MPLS PW TP' (9.8.14), which in turn is connected to '(Extended) VLAN tag op' (9.3.12-13) and to a third 'OR' node. This third 'OR' node is connected to 'CES service profile' (9.8.3), 'TCP/UDP config data' (9.4.3), and to 'GEM IW TP' (9.2.4). The 'GEM IW TP' is connected to 'GEM port network CTP' and receives data 'From layer 2 ME (802.1p mapper or MAC bridge port configuration data)'. The 'Over IP' node is also connected to 'Pseudowire termination point' (9.8.5), 'RTP pseudowire parms' (9.8.6), and to an 'OR' node labeled 'Over Ethernet'. The 'Over Ethernet' node is connected to 'Ethernet flow TP' (9.8.9), which is also connected to 'GEM IW TP' (9.2.4). Dashed lines connect 'Pseudowire PM history data' (9.8.8) to the 'Pseudowire termination point' and 'PPTP CES UNI', and 'CES phy PM 1, 2, 3' (9.8.4, -12-13) to the 'PPTP CES UNI'. Multiplicity indicators (1, N, 1..n, 0..1) are shown on the connections. The diagram is labeled G.988(12)\_F8.2.9-1 at the bottom right. + +**Figure 8.2.9-1 – Time division multiplex pseudowire** + +![Diagram of ATM pseudowire architecture showing various transport options and configuration data blocks.](a2251e3bbfcd726b68cc50b091e53b02_img.jpg) + +The diagram illustrates the ATM pseudowire (PW) architecture, centered around the **PW ATM config data** block (9.8.15). This central block is connected to several other components: + +- PW ATM PM history data** (9.8.16) is connected via a dashed line to the **PW ATM config data** block. +- ITU-T G.983.2 traffic descriptor** ([ITU-T G.983.2], 7.5.2) is connected via a solid line with a 1:n multiplicity. +- ITU-T G.983.2 PTP ATM UNI** ([ITU-T G.983.2], 7.3.1) is connected via a solid line with a 1:n multiplicity. +- ITU-T G.983.2 UNIB-PON** ([ITU-T G.983.2], 7.3.5) is connected via a dashed line to the **ITU-T G.983.2 PTP ATM UNI** block. + +The **PW ATM config data** block is also connected to two **OR** (OR) nodes, which represent different transport options: + +- Over UDP:** This path leads to a **TCP/UDP config data** (9.4.3) block and an **MPLS PW TP** (9.8.14) block. The **MPLS PW TP** block is connected to an **OR** node, which in turn connects to: + - Over GEM:** Leads to a **GEM IW TP** (9.2.4) block, which connects to a **GEM port network CTP** (1). + - Over MPLS:** Leads to an **Ethernet flow TP** (9.8.9) block, which connects to a **From layer 2 ME (802.1p mapper or MAC bridge port configuration data)** (0..1). + - Over Ethernet:** Leads to another **OR** node, which connects to: + - Over UDP:** Leads to a **TCP/UDP config data** (9.4.3) block. +- Over GEM:** This path leads directly to a **GEM IW TP** (9.2.4) block, which connects to a **GEM port network CTP** (1). + +Additional configuration blocks are shown with arrows pointing to specific transport paths: + +- (Extended) VLAN tag op** (9.3.12-13) points to the **MPLS PW TP** (9.8.14) block. + +The diagram is labeled with **G.988(12)\_F8.2.9-2** at the bottom right. + +Diagram of ATM pseudowire architecture showing various transport options and configuration data blocks. + +**Figure 8.2.9-2 – ATM pseudowire** + +![Figure 8.2.9-3 – Ethernet pseudowire. This block diagram shows the architecture of an Ethernet pseudowire. At the top, 'TCP/UDP config data' (9.4.3) and 'GEM IW TP' (9.2.4) are connected to an 'OR' node. 'TCP/UDP config data' is labeled 'Over UDP' and 'GEM IW TP' is labeled 'Over GEM'. 'GEM IW TP' has an outgoing connection to 'GEM port network CTP' (multiplicity 1) and is also labeled 'From layer 2 ME (802.1p mapper or MAC bridge port configuration data)'. The 'OR' node connects to 'Ethernet flow TP' (9.8.9) via a '1' multiplicity connection. 'Ethernet flow TP' has an outgoing connection with '0..1' multiplicity. The 'OR' node also connects to 'MPLS PW TP' (9.8.14) via an 'Over MPLS' connection. 'MPLS PW TP' is connected to '(Extended) VLAN tag op' (9.3.12-13) and 'PW Ethernet config data' (9.8.17). 'PW Ethernet config data' is connected to 'Ethernet pseudowire parms' (9.8.18) via a dashed line. Below 'PW Ethernet config data' is another 'OR' node, which connects to 'MAC bridge port config data' (9.3.4) via a '1..n' multiplicity connection. The 'OR' node also connects to 'PPTP xx UNI' (9.12.1) via a '1..n' multiplicity connection. 'UNI-G' (9.12.1) is connected to 'PPTP xx UNI' via a dashed line. The diagram is labeled 'G.988(12)_F8.2.9-3'.](cbab05075b3d7dc0d27c4cbb0c914a94_img.jpg) + +Figure 8.2.9-3 – Ethernet pseudowire. This block diagram shows the architecture of an Ethernet pseudowire. At the top, 'TCP/UDP config data' (9.4.3) and 'GEM IW TP' (9.2.4) are connected to an 'OR' node. 'TCP/UDP config data' is labeled 'Over UDP' and 'GEM IW TP' is labeled 'Over GEM'. 'GEM IW TP' has an outgoing connection to 'GEM port network CTP' (multiplicity 1) and is also labeled 'From layer 2 ME (802.1p mapper or MAC bridge port configuration data)'. The 'OR' node connects to 'Ethernet flow TP' (9.8.9) via a '1' multiplicity connection. 'Ethernet flow TP' has an outgoing connection with '0..1' multiplicity. The 'OR' node also connects to 'MPLS PW TP' (9.8.14) via an 'Over MPLS' connection. 'MPLS PW TP' is connected to '(Extended) VLAN tag op' (9.3.12-13) and 'PW Ethernet config data' (9.8.17). 'PW Ethernet config data' is connected to 'Ethernet pseudowire parms' (9.8.18) via a dashed line. Below 'PW Ethernet config data' is another 'OR' node, which connects to 'MAC bridge port config data' (9.3.4) via a '1..n' multiplicity connection. The 'OR' node also connects to 'PPTP xx UNI' (9.12.1) via a '1..n' multiplicity connection. 'UNI-G' (9.12.1) is connected to 'PPTP xx UNI' via a dashed line. The diagram is labeled 'G.988(12)\_F8.2.9-3'. + +**Figure 8.2.9-3 – Ethernet pseudowire** + +### 8.2.10 Mid-span PON reach extenders + +The PON RE is modelled as an ONU (the management entity) containing cardholders and circuit packs whose functions are to extend the reach of one or more PONs. The management ONU of the PON RE is understood to exist as a member of one of the extended PONs. See Figures 8.2.10-1 to 8.2.10-5. + +![Figure 8.2.10-1 – Mid-span PON reach extender core (repeater). This block diagram shows the connection between a 'PPTP RE UNI' (9.14.2) and an 'RE ANI-G' (9.14.1). The 'PPTP RE UNI' has a '1' multiplicity connection to the 'RE ANI-G', which has a '0..255' multiplicity connection. The diagram is labeled 'G.988(12)_F8.2.10-1'.](0a06de972d61ab9bb901bd74dd4ff51f_img.jpg) + +Figure 8.2.10-1 – Mid-span PON reach extender core (repeater). This block diagram shows the connection between a 'PPTP RE UNI' (9.14.2) and an 'RE ANI-G' (9.14.1). The 'PPTP RE UNI' has a '1' multiplicity connection to the 'RE ANI-G', which has a '0..255' multiplicity connection. The diagram is labeled 'G.988(12)\_F8.2.10-1'. + +NOTE – In many cases, the RE ANI-G and PPTP RE UNI are implemented on the same circuit pack. If so, the port-mapping package can be used to create the hybrid line card. + +**Figure 8.2.10-1 – Mid-span PON reach extender core (repeater)** + +![Figure 8.2.10-2 – Mid-span PON reach extender core (optical amplifier). This block diagram shows the connection between an 'RE upstream amplifier' (9.14.3) and an 'RE downstream amplifier' (9.14.4). The 'RE upstream amplifier' has a '1' multiplicity connection to the 'RE downstream amplifier', which has a '0..255' multiplicity connection. Both amplifiers are connected to 'RE common amplifier parms' (9.14.6) via dashed lines. The diagram is labeled 'G.988(12)_F8.2.10-2'.](d7948c38a18636aefecdd95388196460_img.jpg) + +Figure 8.2.10-2 – Mid-span PON reach extender core (optical amplifier). This block diagram shows the connection between an 'RE upstream amplifier' (9.14.3) and an 'RE downstream amplifier' (9.14.4). The 'RE upstream amplifier' has a '1' multiplicity connection to the 'RE downstream amplifier', which has a '0..255' multiplicity connection. Both amplifiers are connected to 'RE common amplifier parms' (9.14.6) via dashed lines. The diagram is labeled 'G.988(12)\_F8.2.10-2'. + +NOTE – In many cases, the RE upstream amplifier and RE downstream amplifier are implemented on the same circuit pack. If so, the port-mapping package can be used to create the hybrid line card. + +**Figure 8.2.10-2 – Mid-span PON reach extender core (optical amplifier)** + +![Diagram of Mid-span upstream PON reach extender core (hybrid)](c0b9e5fc63e19306394e0d4249da62cd_img.jpg) + +This diagram illustrates the mid-span upstream PON reach extender core (hybrid). It features three main components: a PTP RE UNI (9.14.2), an RE common amplifier parms (9.14.6), and an RE ANI-G (9.14.1). The PTP RE UNI is connected to the RE ANI-G via a solid line labeled '1' at the UNI and '0..255' at the ANI-G. The RE common amplifier parms are connected to both the PTP RE UNI and the RE ANI-G via dashed lines. The RE ANI-G is also connected to an RE upstream amplifier (9.14.3) via a dashed line. The RE ANI-G is labeled with G.988(12)\_F8.2.10-3. + +Diagram of Mid-span upstream PON reach extender core (hybrid) + +**Figure 8.2.10-3 – Mid-span upstream PON reach extender core (hybrid)** + +![Diagram of Mid-span downstream PON reach extender core (hybrid)](3c99312f83459559d9a301148555d7b9_img.jpg) + +This diagram illustrates the mid-span downstream PON reach extender core (hybrid). It features three main components: a PTP RE UNI (9.14.2), an RE common amplifier parms (9.14.6), and an RE ANI-G (9.14.1). The PTP RE UNI is connected to the RE ANI-G via a solid line labeled '1' at the UNI and '0..255' at the ANI-G. The RE common amplifier parms are connected to both the PTP RE UNI and the RE ANI-G via dashed lines. The RE ANI-G is also connected to an RE downstream amplifier (9.14.4) via a dashed line. The RE ANI-G is labeled with G.988(12)\_F8.2.10-4. + +Diagram of Mid-span downstream PON reach extender core (hybrid) + +**Figure 8.2.10-4 – Mid-span downstream PON reach extender core (hybrid)** + +![Diagram of In-band management for the mid-span PON reach extender](e417ae35ab07134888be901c201d54cd_img.jpg) + +This diagram illustrates the in-band management for the mid-span PON reach extender. It shows a MAC bridge port config data (9.3.4) connected to a PTP RE UNI (9.14.2) via a solid line labeled '1'. The MAC bridge port config data is also connected to a 'To MAC bridge service per existing in-band management protocol server' via a dashed line. The PTP RE UNI is connected to an IP or IPv6 host config data (9.4.1, 9.4.5) via a solid line labeled '0..1'. The IP or IPv6 host config data is connected to a TCP/UDP config data (9.4.3) via a solid line labeled '1'. The TCP/UDP config data is connected to an RE config portal (9.14.5) via a solid line labeled '0..1'. The RE config portal is connected to the PTP RE UNI via a dashed line labeled '1'. The RE config portal is labeled with G.988(12)\_F8.2.10-5. + +Diagram of In-band management for the mid-span PON reach extender + +**Figure 8.2.10-5 – In-band management for the mid-span PON reach extender** + +### **8.2.11 Point-to-point gigabit Ethernet fed ONU** + +See Figure 8.2.11-1. + +![Diagram of P2P GbE-fed ONU](39536a630fa74c3bcfd1670ee2152809_img.jpg) + +This diagram illustrates the P2P GbE-fed ONU. It features three main components: a PTP Ethernet UNI (9.5.1), an ONU-E (9.1.13), and an ONU data (9.1.3). The PTP Ethernet UNI is connected to the ONU-E via a dashed line labeled '1' at the UNI and 'M' at the ONU-E. The ONU-E is connected to the ONU data via a dashed line labeled '1' at the ONU-E and '1' at the ONU data. The ONU data is labeled with G.988(12)\_F8.2.11-1. + +Diagram of P2P GbE-fed ONU + +**Figure 8.2.11-1 – P2P GbE-fed ONU** + +### 8.2.12 Link aggregation service profile + +In the LAG-based channel bonding, traffic to a LAG group goes to multiple GEM ports and multiple ANI-G interfaces. When the LAG-based channel bonding is employed, multiple MAC bridge port configuration data MEs point to a link aggregation service profile (LASP) ME. + +See Figure 8.2.12-1. + +![Figure 8.2.12-1 – Link aggregation. A complex network diagram showing the relationships between various Management Entity (ME) objects for link aggregation. The diagram includes nodes for Extended VLAN tag op, VLAN tag op config data, Link Agg service profile, GEM port network CTP, GAL Ethernet PM, MAC bridge service profile, MAC bridge PM, VLAN tagging filter data, MAC bridge config data, MAC bridge port config data, MAC bridge port filter table, MB port filter pre-assign table, UNI-G, PTPP xx UNI, Enet frame PM, up/dn, MB port designation data, and MB port PM. Relationships are shown with lines and multiplicity indicators like 0..n, 1, 0..1, 0..w, 0..m, 0..p.](9b1ec0090070bdf52ea28763b8d52477_img.jpg) + +The diagram illustrates the network of Management Entity (ME) objects for link aggregation. At the top, 'Extended VLAN tag op' (9.3.13) points to 'Any ME to which VLAN tagging can be assigned', which in turn points to 'VLAN tag op config data' (9.3.12). A '(Flexible association)' line connects 'VLAN tag op config data' to 'Enet frame extended PM' (9.3.32). Below this, 'Link Agg service profile' (9.3.35) is connected to 'GEM interworking TP' (9.2.4) with a 0..n multiplicity. 'GEM interworking TP' is connected to 'GEM port network CTP' (9.2.3) with a 1 multiplicity and to 'GAL Ethernet PM' (9.2.8) with a 0..1 multiplicity. 'GAL Ethernet PM' is connected to 'GAL Ethernet profile' (9.2.7) with a 1 multiplicity. 'MAC bridge service profile' (9.3.1) is connected to 'Dot1 rate limiter' (9.3.18) with a 1 multiplicity and to 'MAC bridge PM' (9.3.3) with a 0..1 multiplicity. 'MAC bridge PM' is connected to 'MAC bridge port config data' (9.3.4) with a 1 multiplicity. 'MAC bridge port config data' is connected to 'MAC bridge config data' (9.3.2) with a 1 multiplicity and to 'PPTP xx UNI' (9.3.4) with a 0..1 multiplicity. 'PPTP xx UNI' is connected to 'UNI-G' (9.12.1) with a 1 multiplicity. 'MAC bridge port config data' is also connected to 'MAC bridge port filter table' (9.3.6) with a 1 multiplicity. 'MAC bridge port filter table' is connected to 'VLAN tagging filter data' (9.3.11) with a 1 multiplicity and to 'MB port filter pre-assign table' (9.3.7) with a 1 multiplicity. 'MAC bridge port config data' is also connected to 'MAC bridge port bridge table' (9.3.8) with a 1 multiplicity. 'MAC bridge port bridge table' is connected to 'Enet frame PM, up/dn' (9.3.30-31) with a 1 multiplicity and to 'MB port designation data' (9.3.5) with a 1 multiplicity. 'MB port designation data' is connected to 'MB port PM' (9.3.9) with a 1 multiplicity. The diagram also shows various other connections and multiplicities between these components. + +Figure 8.2.12-1 – Link aggregation. A complex network diagram showing the relationships between various Management Entity (ME) objects for link aggregation. The diagram includes nodes for Extended VLAN tag op, VLAN tag op config data, Link Agg service profile, GEM port network CTP, GAL Ethernet PM, MAC bridge service profile, MAC bridge PM, VLAN tagging filter data, MAC bridge config data, MAC bridge port config data, MAC bridge port filter table, MB port filter pre-assign table, UNI-G, PTPP xx UNI, Enet frame PM, up/dn, MB port designation data, and MB port PM. Relationships are shown with lines and multiplicity indicators like 0..n, 1, 0..1, 0..w, 0..m, 0..p. + +Figure 8.2.12-1 – Link aggregation + +### 8.2.13 ONU packet-based TimeSynchronization + +See Figure 8.2.13-1. + +![Diagram of ONU packet-based Time Synchronization showing relationships between various Management Entities (MEs) and the ONU-G. The central node is ONU-G (9.1.1). It is connected to: Precision time protocol (9.12.22) via a 1:0..1 relationship; Time status message (9.12.19) via a 1:0..1 relationship; Synchronous Ethernet operations (9.12.21) via a 1:0..1 relationship; and ONU time configuration (9.1.17) via a 1:0..1 relationship. Precision time protocol (9.12.22) is further connected to Precision time protocol status (9.12.23) via a 1:1 relationship.](c2c4e63ebb9afc1ab64e39a159890e0f_img.jpg) + +``` + +graph TD + ONU-G["ONU-G +9.1.1"] + PTP["Precision time protocol +9.12.22"] + TSM["Time status message +9.12.19"] + SEO["Synchronous Ethernet operations +9.12.21"] + OTC["ONU time configuration +9.1.17"] + PTPS["Precision time protocol status +9.12.23"] + + ONU-G -- "1" --- PTP + PTP -- "0..1" --- ONU-G + ONU-G -- "1" --- TSM + TSM -- "0..1" --- ONU-G + ONU-G -- "1" --- SEO + SEO -- "0..1" --- ONU-G + ONU-G -- "1" --- OTC + OTC -- "0..1" --- ONU-G + PTP -- "1" --- PTPS + PTPS -- "1" --- PTP + +``` + +G.988(22)\_F8.2.13-1 + +Diagram of ONU packet-based Time Synchronization showing relationships between various Management Entities (MEs) and the ONU-G. The central node is ONU-G (9.1.1). It is connected to: Precision time protocol (9.12.22) via a 1:0..1 relationship; Time status message (9.12.19) via a 1:0..1 relationship; Synchronous Ethernet operations (9.12.21) via a 1:0..1 relationship; and ONU time configuration (9.1.17) via a 1:0..1 relationship. Precision time protocol (9.12.22) is further connected to Precision time protocol status (9.12.23) via a 1:1 relationship. + +**Figure 8.2.13-1 – ONU packet-based Time Synchronization** + +# 9 MIB description + +This clause defines all ONU MEs of interest to the Recommendations that subscribe to it. Recognizing the heritage of the OMCI through [ITU-T G.983.2], code points for a number of MEs are permanently reserved for legacy implementations. In a few cases, MEs defined in earlier Recommendations have proven to be of little interest. As reserved code points, such MEs remain available for use in new applications, if needed, but their definitions appear only in the original Recommendations. + +ME descriptions include: + +- a) The purpose of the entity. +- b) The relationships of the ME with other MEs. +- c) The attributes of the entity, an ordered list that specifies both syntax and semantics. +- d) The management operations (actions) that may be performed on the entity. Generic actions such as create, delete, get, get next, set and get current data are merely listed in the description of a given ME; details appear in Annex A. Specialized actions are described in more detail in the ME description itself. +- e) The notifications generated by the ME. These may be attribute value changes (AVCs), alarms or performance monitoring threshold crossing alerts (TCAs). Tables define each of these three classes as needed for each ME type. + +These clauses are organized as follows. + +- 9.1 Equipment management +- 9.2 ANI management, traffic management +- 9.3 Layer 2 data services +- 9.4 Layer 3 data services +- 9.5 Ethernet services +- 9.6 This clause is intentionally left blank +- 9.7 xDSL services +- 9.8 Time division multiplex services +- 9.9 Voice services + +- 9.10 Premises networks +- 9.11 This clause is intentionally left blank +- 9.12 General purpose managed entities +- 9.13 Miscellaneous services +- 9.14 Mid-span passive optical network reach extender + +## Attribute access + +Some MEs are instantiated by the ONU autonomously. Others are instantiated on explicit request of the OLT via a create command, and a few ME types may be instantiated in either way, depending on the ONU architecture or circumstances. + +Attributes of an ME that is auto-instantiated by the ONU can be read (R), write (W), or read, write (R, W). + +On the other hand, attributes of a ME that is instantiated by the OLT can be either (R), (W), (R, W), (R, set-by-create) or (R, W, set-by-create). Where appropriate, this Recommendation specifies a default value, to be assigned to the attribute on instantiation of the ME. + +The following explains each case in more detail: + +- (R): At instantiation or initialization, the ONU sets the attribute to a default value or to a value that reflects a current state or measurement. During continued operation, the ONU may update the value of the attribute to reflect state or measurement changes. The OLT can only read the value of the attribute. In the case of an autonomous AVC, the ONU may send an AVC notification to the OLT. +- (W): The OLT can only write the value of this attribute type. An attribute of this type is typically used to trigger an action in the ONU. Such an attribute never triggers an AVC notification to the OLT. +- (R, W): On instantiation of the ME, either autonomously or on request of the OLT via a create action, the ONU sets the attribute to a default value. The OLT can both read and write the value of the attribute. In the case of an autonomous AVC, the ONU may send an AVC notification to the OLT. +- (R, set-by-create): On instantiation of the ME, by necessity on request of the OLT via a create action, the ONU sets the attribute to the value specified in the create command. Subsequently, the OLT cannot change the value of the attribute. This combination is used mostly for ME IDs, but occasionally for other attributes that cannot meaningfully change after ME creation. +- (RW, set-by-create): On instantiation of the ME, by necessity on request of the OLT via a create action, the ONU sets the attribute to the value specified in the create command. Subsequently, the OLT can both read and write the value of the attribute. In the case of an autonomous AVC, the ONU may send an AVC notification to the OLT. In a number of cases, it is logically impossible to change (write) the value of an attribute after the ME has been created. However, chicken and egg issues can arise when several such MEs point to each other. Allowing such attributes to be set after creation is intended to avoid these issues. + +## Managed entity identifiers + +The identifier (ID) of an ME may be a fixed value, stated in its definition. The ME ID may be specified as 0 when the ME is instantiated automatically and there is only one. The ONU-G ME is a good + +example of this class. In other cases, the definition of an ME specifies a rule for the assignment of an ME ID, such as a slot-port model. + +When an ME is created by the OLT, and its ME ID is unconstrained by the ME definition in clause 9, it is preferred to avoid ME IDs 0 and 0xFFFF, which create ambiguity in pointers that may need to refer to the ME. + +Likewise, when an ME is created by the ONU, and its ME ID is free for the ONU to choose, the ONU should avoid ME IDs 0 and 0xFFFF. + +## Optional pointers + +In many cases, populating a pointer attribute may be optional (a prime example being the threshold data 1/2 ID attribute). When this happens, it is useful to be able to specify a null pointer in the OMCI. Because the OLT defines the pointers and the MEs to which they point, if the OLT has the intention to not populate the optional pointer, it can do so by filling in any value that does not correspond to an ME that exists. The ONU can determine that the pointer points to nothing, and is therefore null. Both 0 and 0xFFFF are often used by convention to designate a null pointer, but especially the value 0 can sometimes be a valid ME ID, so this convention should be used judiciously. + +## Interdependent attribute handling + +Some attributes within an ME are interdependent. For example, attribute B may be used to enable/disable the use of attribute A. In these cases, it is recommended that the OLT provision the dependent attribute (A) first or in the same set message. If the attributes are provisioned in an order that causes the use of an unprovisioned attribute with no well-defined default, the OLT cannot necessarily expect an error indication from the ONU and the correct operation of the ONU cannot be guaranteed. In most cases, default values are defined in clause 9 to minimize the risk of this event. + +### Notifications + +The notifications generated by a ME stem from the following events: alarms, AVCs, TCAs and test results. + +Alarms, TCAs and failures of autonomous self-tests are all reported via alarm messages. The alarm-reporting message contains a field of 224 bits, which is mapped to as many as 208 specific alarms by the definition of each ME. The last 16 bits are reserved for vendor-specific alarms and are not to be standardized. Alarm bits are numbered from 0 upwards. The general schema is illustrated in the following table, where each ME definition may specify some of the 208 reserved points for its own alarms. Different ME types can reuse the same code points because the alarm report message includes the ME type (and instance). + +### Generic alarm bit assignment + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------| +| 0..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +AVCs are reported via AVC messages. An ME cannot encompass more than 16 attributes, in addition to its ME ID, and the AVC message contains a bit map of 16 bits that match the attributes in order, starting with 1. If an ME can generate AVCs, its definition includes an AVC table that matches attributes with their corresponding bit numbers for easy reference. Attributes that do not trigger AVC notifications are shown as N/A, while bit positions for non-existent attributes are shown as reserved. + +Test results are reported: + +- a) via an expected test result message if the test is invoked by a test command from the OLT; +or +- b) via an autonomous test result message if a test failure is detected autonomously by the ONU; +or +- c) via an alarm message in the case of autonomous self-test failure in the start-up phase. + +Details of these messages and their coding appear in Annex A. + +### **IPv6 address representation** + +The OMCI management information model was developed in the context of IPv4, which uses 4 byte addresses. IPv6 requires 16 bytes to fully represent an address. It is undesirable to define completely new MEs for IPv6, and both versions are likely to coexist for some time. + +It is observed that 0.0.x.y is not a valid IPv4 address, although 0.0.0.0 may appear occasionally, for example in Internet group management protocol (IGMP) messages. + +This Recommendation specifies that, for any 4 byte attribute defined as an IP address, mask or gateway, if the value is 0.0.x.y, where *x* and *y* are not both 0, then *x.y* is to be interpreted as a pointer to a large string ME that represents an IPv6 address. The syntax of the representation is described in [b-IETF RFC 4291]. When explicitly allowed for an individual attribute, the large string may also contain a URI. + +Usually, large strings are created and deleted by the OLT. For IPv6 address representation, the ONU may also need to create and delete a large string. To avoid numbering conflicts, it is recommended that the OLT number large strings from 1 upwards, while the ONU number auto-created large strings from 65 534 downwards. + +MEs whose IP addresses are treated in accordance with this clause include: + +- Dot 1X configuration profile; +- Multicast operations profile, querier IP address attribute. In this attribute, 0.0.0.0 is legal in IPv4; +- SIP agent config data, SIP domain name server (DNS) address attributes; +- SNMP configuration data. + +The mechanism described in this clause is suitable for individual IPv6 address attributes, but it does not scale well for MEs that contain tables of IP addresses. Each of these MEs has its own definition of IPv6 treatment. In the future, any new MEs are to be defined with inbuilt IPv6 support. + +## **9.1 Equipment management** + +An ONU may be physically implemented as a single module (integrated ONU) or as a shelf containing plug-in field-replaceable units (FRUs). An ONU containing FRUs always instantiates a cardholder ME for each of its physical slots; a cardholder can then be populated with a circuit pack. It is recommended that physical slots be numbered from left to right, then from bottom to top. + +Because the cardholder ID (slot number) is used in the ME ID of many MEs, an integrated ONU may also be conveniently modelled with virtual cardholders and virtual circuit (VC) packs. When an ONU is modelled with virtual cardholders and circuit packs, it makes sense that all ports of a given VC pack have the same type, e.g., IEEE 802.3 Ethernet. + +However, a physical circuit pack may have several port types, e.g., a PON ANI, a video UNI and a craft port. The port-mapping package provides a flexible way to associate port numbers with a heterogeneous assortment of ports. + +In the same way, the port-mapping package supports an integrated ONU that is modelled without virtual cardholders. In such an ONU, ME IDs are assigned with the understanding that all MEs exist in cardholder 0. + +### 9.1.1 ONU-G + +This ME represents the ONU as equipment. The ONU automatically creates an instance of this ME. It assigns values to read-only attributes according to data within the ONU itself. + +This ME has evolved from the ONT-G of [ITU-T G.984.4]. + +#### *Relationships* + +In ITU-T GTC based PON applications, all other MEs in this Recommendation are related directly or indirectly to the ONU-G entity. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Vendor ID:** This attribute identifies the vendor of the ONU. It is the same as the four most significant bytes of the ONU serial number as specified in the respective transmission convergence (TC) layer specification. (R) (mandatory) (4 bytes) + +**Version:** This attribute identifies the version of the ONU as defined by the vendor. The character value 0 indicates that version information is not available or applicable. (R) (mandatory) (14 bytes) + +**Serial number:** The serial number is unique for each ONU. It is defined in the respective TC layer specification and contains the vendor ID and version number. The first four bytes are an ASCII-encoded four-letter vendor ID. The second four bytes are a binary encoded serial number, under the control of the ONU vendor. (R) (mandatory) (8 bytes) + +**Traffic management option:** This attribute identifies the upstream traffic management function implemented in the ONU. There are three options: + +- 0 Priority controlled and flexibly scheduled upstream traffic. The traffic scheduler and priority queue mechanism are used for upstream traffic. +- 1 Rate controlled upstream traffic. The maximum upstream traffic of each individual connection is guaranteed by shaping. +- 2 Priority and rate controlled. The traffic scheduler and priority queue mechanism are used for upstream traffic. The maximum upstream traffic of each individual connection is guaranteed by shaping. + +For a further explanation, see Appendix II. + +Downstream priority queues are managed via the GEM port network CTP ME. + +Upon ME instantiation, the ONU sets this attribute to the value that describes its implementation. The OLT must adapt its model to conform to the ONU's selection. (R) (mandatory) (1 byte) + +**Deprecated:** This attribute is not used. If it is present, it should be set to 0. (R) (optional) (1 byte) + +**Battery backup:** This Boolean attribute controls whether the ONU performs backup battery monitoring (assuming it is capable of doing so). *False* disables battery alarm monitoring; *true* enables battery alarm monitoring. (R, W) (mandatory) (1 byte) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by the ONU as an entirety. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute reports whether the ME is currently capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ONU survival time:** This attribute indicates the minimum guaranteed time in milliseconds between the loss of external power and the silence of the ONU. This does not include survival time attributable to a backup battery. The value zero implies that the actual time is not known. (R) (optional) (1 byte) + +**Logical ONU ID:** This attribute provides a way for the ONU to identify itself. It is a text string, null terminated if it is shorter than 24 bytes, with a null default value. The mechanism for creation or modification of this information is beyond the scope of this Recommendation, but might include, for example, a web page displayed to a user. (R) (optional) (24 bytes) + +**Logical password:** This attribute provides a way for the ONU to submit authentication credentials. It is a text string, null terminated if it is shorter than 12 bytes, with a null default value. The mechanism for creation or modification of this information is beyond the scope of this Recommendation. (R) (optional) (12 bytes) + +**Credentials status:** This attribute permits the OLT to signal to the ONU whether its credentials are valid or not. The behaviour of the ONU is not specified, but might, for example, include displaying an error screen to the user. (R, W) (optional) (1 byte) + +Values include: + +- 0 Initial state, status indeterminate + - 1 Successful authentication + - 2 Logical ONU ID (LOID) error + - 3 Password error + - 4 Duplicate LOID +- Other values are reserved. + +**Extended TC-layer options:** This attribute is meaningful in ITU-T G.984 systems only. It is a bit map that defines whether the ONU supports (1) or does not support (0) various optional TC-layer capabilities of [ITU-T G.984.3]. Bits are assigned as follows. + +| Bit | Meaning | +|---------|------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Annex C of [ITU-T G.984.3], PON-ID maintenance. | +| 2 | Annex D of [ITU-T G.984.3], PLOAM channel enhancements: swift_POPUP and Ranging_adjustment messages. | +| 3..16 | Reserved | + +(R) (optional) (2 bytes) + +#### Actions + +#### Get, set + +**Reboot:** Reboot the ONU. + +**Test:** Test the ONU. The test action can be used either to perform equipment diagnostics or to measure parameters such as received optical power, video + +output level, battery voltage, etc. Test and test result messages are defined in Annex A. + +**Synchronize time:** This action synchronizes the start time of all PM MEs of the ONU with the reference time of the OLT. All counters of all PM MEs are cleared to 0 and restarted. Also, the value of the interval end time attribute of the PM MEs is set to 0 and restarted. See clause I.4 for further discussion of PM. + +NOTE – This function is intended only to establish rough 15 min boundaries for PM collection. High precision time of day synchronization is a separate function, supported by the OLT-G ME. + +#### Notifications + +**Test result:** Test results are reported via a test result message if the test is invoked by a test command from the OLT. + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..7 | N/A | | +| 8 | Op state | Operational state change | +| 9 | N/A | | +| 10 | LOID | Logical ONU ID | +| 11 | Lpw | Logical password | +| 12..16 | Reserved | | + +#### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Equipment alarm | Functional failure on an internal interface | +| 1 | Powering alarm | Loss of external power to battery backup unit. This alarm is typically derived through an external interface to a battery backup unit, and indicates that AC is no longer available to maintain battery charge. | +| 2 | Battery missing | Battery is provisioned but missing | +| 3 | Battery failure | Battery is provisioned and present but cannot recharge | +| 4 | Battery low | Battery is provisioned and present but its voltage is too low | +| 5 | Physical intrusion | Applies if the ONU supports detection such as door or box open | +| 6 | ONU self-test failure | ONU has failed autonomous self-test | +| 7 | Dying gasp | ONU is powering off imminently due to loss of power to the ONU itself. This alarm may be sent in conjunction with the powering alarm if the backup unit cannot supply power and the ONU is shutting down. | +| 8 | Temperature yellow | No service shutdown at present, but the circuit pack is operating beyond its recommended range. | +| 9 | Temperature red | Some services have been shut down to avoid equipment damage. The operational state of the affected PPTPs indicates the affected services. | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 10 | Voltage yellow | No service shutdown at present, but the line power voltage is below its recommended minimum. Service restrictions may be in effect, such as permitting no more than N lines off-hook or ringing at one time. | +| 11 | Voltage red | Some services have been shut down to avoid power collapse. The operational state of the affected PPTPs indicates the affected services. | +| 12 | ONU manual power off | The ONU is shutting down because the subscriber has turned off its power switch. | +| 13 | Inv-Image | Software image is invalid (Note) | +| 14 | PSE overload yellow | Indicates that the ONU is nearing its maximum ability to supply the known PoE demand of the attached PDs. The thresholds for declaring and clearing this alarm are vendor-specific. | +| 15 | PSE overload red | Indicates that the ONU is unable to supply all of the PoE demand of the attached PDs and has removed or reduced power to at least one PD. | +| 16..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +NOTE – The ONU should declare this alarm only outside the software download process. + +### 9.1.2 ONU2-G + +This ME contains additional attributes associated with a PON ONU. The ONU automatically creates an instance of this ME. Its attributes are populated according to data within the ONU itself. + +This ME is the same as the ONT2-G of [ITU-T G.984.4], with extensions. + +#### Relationships + +This ME is paired with the ONU-G entity. + +##### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Equipment ID:** This attribute may be used to identify the specific type of ONU. In some environments, this attribute may include the common language equipment identification (CLEI) code. (R) (optional) (20 bytes) + +**Optical network unit management and control channel (OMCC) version:** This attribute identifies the version of the OMCC protocol being used by the ONU. This allows the OLT to manage a network with ONUs that support different OMCC versions. Release levels of [ITU-T G.984.4] are supported with code points of the form 0x8y and 0x9y, where y is a hexadecimal digit in the range 0..F. Support for continuing revisions of this Recommendation is defined in the 0xAy and 0xBy range. + +NOTE 1 – The complete list of managed entities supported by an ONU cannot be derived from the OMCC version attribute. Refer to other ITU-T G.988 OMCI mechanisms for deriving this information (clause I.1.1.1 which describes the use of clauses 9.12.9 Managed entity and 9.12.10 Attribute ME + +for retrieval of ITU-T G.988 supported ME, and clause I.1.2 for discovering the ONU hardware and service configuration of the ONU through MIB uploads.) + +NOTE 2 – 0xBz values greater than B5 are reserved to report new ITU-T G.988 Annex A message versions (relative to ITU-T G.988 (2014) Amd1). + +0x80 ITU-T G.984.4 (06/04) + +NOTE – For historical reasons, this code point may also appear in ONUs that support later versions of [ITU-T G.984.4]. + +0x81 ITU-T G.984.4 2004 Amd.1 (06/05) + +0x82 ITU-T G.984.4 2004 Amd.2 (03/06) + +0x83 ITU-T G.984.4 2004 Amd.3 (12/06) + +0x84 ITU-T G.984.4 2008 (02/08) + +0x85 ITU-T G.984.4 2008 Amd.1 (06/09) + +0x86 ITU-T G.984.4 2008 Amd.2 (2009). Baseline message set only, without the extended message set option + +0x96 ITU-T G.984.4 2008 Amd.2 (2009). Extended message set option, in addition to the baseline message set. + +0xA0 ITU-T G.988 (2010). Baseline message set only, without the extended message set option + +0xA1 ITU-T G.988 Amd.1 (2011). Baseline message set only + +0xA2 ITU-T G.988 Amd.2 (2012). Baseline message set only + +0xA3 ITU-T G.988 (2012). Baseline message set only + +0xA4 ITU-T G.988 Amd. 1 (2014). Baseline message set only + +0xB0 ITU-T G.988 (2010). Baseline and extended message set + +0xB1 ITU-T G.988 Amd.1 (2011). Baseline and extended message set + +0xB2 ITU-T G.988 Amd.2 (2012). Baseline and extended message set + +0xB3 ITU-T G.988 (2012). Baseline and extended message set + +0xB4 ITU-T G.988 Amd1 (2014) Baseline and extended message set + +0xB5 Do not use + +(R) (mandatory) (1 byte) + +**Vendor product code:** This attribute contains a vendor-specific product code for the ONU. + +(R) (optional) (2 bytes) + +**Security capability:** This attribute advertises the security capabilities of the ONU. The following code points are defined: + +| | | +|---------|------------------------------------------------------------------------------------------| +| 0 | Reserved | +| 1 | Advanced encryption standard-128 (AES-128) payload encryption supported | +| 2 | Reserved | +| 3 | AES-128 and AES-256 payload encryption supported | +| 4...6 | Reserved | +| 7 | AES-128, AES-256, and Camellia-128 payload encryption supported | +| 8...10 | Reserved | +| 11 | AES-128, AES-256, and Camellia-256 payload encryption supported | +| 12...14 | Reserved | +| 15 | AES-128, AES-256, Camellia-128 and Camellia-256 payload encryption supported | +| 16-18 | Reserved | +| 19 | AES-128, AES-256, and SM4(-128) payload encryption supported | +| 20...22 | Reserved | +| 23 | AES-128, AES-256, SM4(-128), and Camellia-128 payload encryption supported | +| 24...26 | Reserved | +| 27 | AES-128, AES-256, SM4(-128), and Camellia-256 payload encryption supported | +| 28...30 | Reserved | +| 31 | AES-128, AES-256, SM4(-128), Camellia-128, and Camellia-256 payload encryption supported | +| 32..255 | Reserved | + +(R) (mandatory) (1 byte) + +NOTE – Reporting of value 1 is not valid for ITU-T G.9804 ONU. + +**Security mode:** This attribute specifies the current security mode of the ONU. All secure (X)GEM ports in an ONU must use the same security mode at any given time. The following code points are defined: + +| | | +|--------|------------------------| +| 0 | Reserved | +| 1 | AES-128 algorithm | +| 2 | AES-256 algorithm | +| 3 | Camellia-128 algorithm | +| 4 | Camellia-256 algorithm | +| 5 | SM4(-128) algorithm | +| 6..255 | Reserved | + +Upon ME instantiation, the ONU sets this attribute to 1, AES-128. After initiation, on request from the OLT, this attribute may be set to one of the algorithms supported by the ONU (as indicated in Security Capability attribute). Setting this attribute to any value supported by the ONU does not imply that any of the (X)GEM ports are encrypted; that process is negotiated at the PLOAM layer. It only signifies that the indicated encryption algorithm set by the OLT is the security mode to be used on any of the (X)GEM ports that the OLT may choose to encrypt. (R, W) (mandatory) (1 byte) + +NOTE – Values other than 1 are only valid for ITU-T G.9804 ONUs. + +**Total priority queue number:** This attribute reports the total number of upstream priority queues that are not associated with a circuit pack, but with the ONU in its entirety. Upon ME instantiation, the ONU sets this attribute to the value that represents its capabilities. (R) (mandatory) (2 bytes) + +**Total traffic scheduler number:** This attribute reports the total number of traffic schedulers that are not associated with a circuit pack, but with the ONU in its entirety. The ONU supports null function, strict priority scheduling and weighted round robin (WRR) from the priority control and guarantee of minimum rate control points of view, respectively. If the ONU has no global traffic schedulers, this attribute is 0. (R) (mandatory) (1 byte) + +**Deprecated:** This attribute should always be set to 1 by the ONU and ignored by the OLT. (R) (mandatory) (1 byte) + +**Total GEM port-ID number:** This attribute reports the total number of GEM port-IDs supported by the ONU. The maximum value is specified in the corresponding TC recommendations. Upon ME instantiation, the ONU sets this attribute to the value that represents its capabilities. (R) (optional) (2 bytes) + +**SysUpTime:** This attribute counts 10 ms intervals since the ONU was last initialized. It rolls over to 0 when full (see [IETF RFC 1213]). (R) (optional) (4 bytes) + +**Connectivity capability:** This attribute indicates the Ethernet connectivity models that the ONU can support. The value 0 indicates that the capability is not supported; 1 signifies support. The following code points are defined. + +| Bit | Model | +|---------|-------------------------------------------| +| 1 (LSB) | N:1 bridging, Figure 8.2.2-3 | +| 2 | 1:M mapping, Figure 8.2.2-4 | +| 3 | 1:P filtering, Figure 8.2.2-5 | +| 4 | N:M bridge-mapping, Figure 8.2.2-6 | +| 5 | 1:MP map-filtering, Figure 8.2.2-7 | +| 6 | N:P bridge-filtering, Figure 8.2.2-8 | +| 7 | N:MP bridge-map-filtering, Figure 8.2.2-9 | +| 8...16 | Reserved | + +NOTE 1 – It is not implied that an ONU may not support other connectivity models. + +(R) (optional) (2 bytes) + +**Current connectivity mode:** This attribute specifies the Ethernet connectivity model that the OLT wishes to use. The following code points are defined. + +| Value | Connectivity model | +|-------|------------------------| +| 0 | No selection (default) | +| 1 | N:1 bridging | +| 2 | 1:M mapping | +| 3 | 1:P filtering | +| 4 | N:M bridge-mapping | +| 5 | 1:MP map-filtering | + +| Value | Connectivity model | +|--------|---------------------------| +| 6 | N:P bridge-filtering | +| 7 | N:MP bridge-map-filtering | +| 8..255 | Reserved | + +NOTE 2 – It is not implied that an ONU supports a given connectivity model only when that model is explicitly selected by this attribute. The ONU is free to support additional models at any and all times. + +(R, W) (optional) (1 byte) + +**Quality of service (QoS) configuration flexibility:** This attribute reports whether various MEs in the ONU are fixed by the ONU's architecture or whether they are configurable. For backward compatibility, and if the ONU does not support this attribute, all such attributes are understood to be hard-wired. (R) (optional) (2 bytes) + +| Bit | Interpretation when bit value = 1 | +|---------|------------------------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Priority queue ME: Port field of related port attribute is RW and can point to any T-CONT or UNI port in the same slot | +| 2 | Priority queue ME: The traffic scheduler pointer is permitted to refer to any other traffic scheduler in the same slot | +| 3 | Traffic scheduler ME: T-CONT pointer is RW | +| 4 | Traffic scheduler ME: Policy attribute is RW | +| 5 | T-CONT ME: Policy attribute is RW | +| 6 | Priority queue ME: Priority field of related port attribute is RW | +| 7..16 | Reserved | + +##### Discussion: + +To allow for the possibility that the OLT does not support flexible configuration, the ONU vendor must assure that the priority queues and traffic schedulers are configured in a meaningful and useful way by factory default, and that this default configuration is restored upon ONU initialization and MIB reset. The specifics of such a configuration are beyond the scope of this Recommendation. + +The ME ID of both the T-CONT and traffic scheduler contains a slot number. Even when attributes in the above list are RW, it is never permitted to change the slot number in a reference. That is, configuration flexibility never extends across slots. It is also not permitted to change the directionality of an upstream queue to downstream or *vice versa*. + +**Priority queue scale factor:** If this optional attribute is implemented, it specifies the scale factor of several attributes of the priority queue ME of clause 9.2.10. The default value of this attribute is 1. (R, W) (optional) (2 bytes) + +NOTE 3 – Some legacy implementations may take the queue scale factor from the GEM block length attribute of the ANI-G ME. That option is discouraged in new implementations. + +#### Actions + +Get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|---------------|-------------------------------|-----------------------------------| +| 1 | N/A | | +| 2 | OMCC version | OMCC version supported in the ONU | +| 3..11 | N/A | | +| 12..16 | Reserved | | + +### **9.1.3 ONU data** + +This ME models the MIB itself. Clause I.1.3 explains the use of this ME with respect to MIB synchronization. + +The ONU automatically creates an instance of this ME, and updates the associated attributes according to data within the ONU itself. + +#### *Relationships* + +One instance of this ME is contained in an ONU. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**MIB data sync:** This attribute is used to check the alignment of the MIB of the ONU with the corresponding MIB in the OLT. MIB data sync relies on this attribute, which is a sequence number that can be checked by the OLT to see if the MIB snapshots for the OLT and ONU match. Refer to clause I.1.2.1 for a detailed description of this attribute. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +#### *Actions* + +#### **Get, set** + +**Get all alarms:** Latch a snapshot of the current alarm statuses of all MEs and reset the alarm message counter. + +**Get all alarms next:** Get the latched alarm status of the next ME(s) within the current snapshot. + +**MIB reset:** Reset the MIB data sync attribute to 0 and reset the MIB of the ONU to its default. The default MIB comprises those MEs that are designated mandatory in the corresponding Recommendation, along with other auto-created MEs whose existence is implicit in the architecture or physical configuration of the ONU. + +For G-PON applications, the minimum default MIB comprises one instance of the ONU-G ME pair, one instance of the ONU data ME, and two instances of the software image ME. + +**MIB upload:** Latch a snapshot (i.e., copy) of the current MIB. Not every ME or every attribute is included in an MIB upload. Table attributes are excluded. Only the control block attributes of PM MEs are uploaded. Other MEs and attributes, such as the PPTP for the local craft terminal (LCT), are excluded as documented in their specific definitions. + +**MIB upload next:** Get the latched attribute values of the next ME(s) within the current snapshot. + +#### *Notifications* + +None. + +### **9.1.4 Software image** + +This ME models an executable software image stored in the ONU (documented here as its fundamental usage). It may also be used to represent an opaque vendor-specific file (vendor-specific usage). + +#### **Fundamental usage** + +The ONU automatically creates two instances of this ME upon the creation of each ME that contains independently manageable software, either the ONU itself or an individual circuit pack. It populates ME attributes according to data within the ONU or the circuit pack. + +Some pluggable equipment may not contain software. Others may contain software that is intrinsically bound to the ONU's own software image. No software image ME need exist for such equipment, though it may be convenient for the ONU to create them to support software version audit from the OLT. In this case, the dependent MEs would support only the get action. + +A slot may contain various equipment over its lifetime, and if software image MEs exist, the ONU must automatically create and delete them as the equipped configuration changes. The identity of the software image is tied to the cardholder. + +When an ONU controller packs are duplicated, each can be expected to contain two software image MEs, managed through reference to the individual controller packs themselves. When this occurs, the ONU should not have a global pair of software images MEs (instance 0), since an action (download, activate, commit) directed to instance 0 would be ambiguous. + +#### *Relationships* + +Two instances of the software image ME are associated with each instance of the ONU or cardholder whose software is independently managed. + +##### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The first byte indicates the physical location of the equipment hosting the software image, either the ONU (0) or a cardholder (1..254). The second byte distinguishes between the two software image ME instances (0..1). (R) (mandatory) (2 bytes) + +**Version:** This string attribute identifies the version of the software. (R) (mandatory) (14 bytes) + +**Is committed:** This attribute indicates whether the associated software image is committed (1) or uncommitted (0). By definition, the committed software image is loaded and executed upon reboot of the ONU or circuit pack. During normal operation, one software image is always committed, while the other is uncommitted. Under no circumstances are both software images allowed to be committed at the same time. On the other hand, both software images could be uncommitted at the same time if both were invalid. Upon ME instantiation, instance 0 is initialized to committed, while instance 1 is initialized to uncommitted (i.e., the ONU ships from the factory with image 0 committed). (R) (mandatory) (1 byte) + +- Is active:** This attribute indicates whether the associated software image is active (1) or inactive (0). By definition, the active software image is one that is currently loaded and executing in the ONU or circuit pack. Under normal operation, one software image is always active while the other is inactive. Under no circumstances are both software images allowed to be active at the same time. On the other hand, both software images could be inactive at the same time if both were invalid. (R) (mandatory) (1 byte) +- Is valid:** This attribute indicates whether the associated software image is valid (1) or invalid (0). By definition, a software image is valid if it has been verified to be an executable code image. The verification mechanism is not subject to standardization; however, it should include at least a data integrity check [e.g., a cyclic redundancy check (CRC)] of the entire code image. Upon ME instantiation or software download completion, the ONU validates the associated code image and sets this attribute according to the result. (R) (mandatory) (1 byte) +- Product code:** This attribute provides a way for a vendor to indicate product code information on a file. It is a character string, padded with trailing nulls if it is shorter than 25 bytes. (R) (optional) (25 bytes) +- Image hash:** This attribute is an MD5 hash of the software image. It is computed at completion of the end download action. (R) (optional) (16 bytes) + +##### *Actions* + +##### **Get** + +Software upgrade is described in clause I.3. All of the following actions are mandatory for ONUs with remotely manageable software. + +- Start download:** Initiate a software download sequence. This action is valid only for a software image instance that is neither active nor committed. +- Download section:** Download a section of a software image. This action is valid only for a software image instance that is currently being downloaded (image 1 in state S2, image 0 in state S2'). +- End download:** Signal the completion of a download image sequence, providing both CRC and version information for final verification. This action is valid only for a software image instance that is currently being downloaded (image 1 in state S2, image 0 in state S2'). +- Activate image:** Load/execute a software image. When this action is applied to a software image that is currently inactive, execution of the current code image is suspended, the associated software image is loaded from non-volatile memory, and execution of this new code image is initiated (i.e., the associated entity reboots on the previously inactive image). When this action is applied to a software image that is already active, a soft restart is performed. The software image is not reloaded from non-volatile memory; the current volatile code image is simply restarted. This action is only valid for a valid software image. +- Commit image:** Set the *is committed* attribute value to 1 for the target software image ME and set the *is committed* attribute value to 0 for the other software image. This causes the committed software image to be loaded and executed by the boot code upon subsequent start-ups. This action is only applicable when the target software image is valid. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Version | | +| 2 | Is committed | | +| 3 | Is active | If an autonomous change to this attribute is associated with an ONU re-boot, the ONU should send the AVC (one for each primary software image instance) after the re-boot. | +| 4 | Is valid | | +| 5 | Product code | | +| 6 | Image hash | | +| 7..16 | Reserved | | + +NOTE – Older implementations of the OMCI may not support these notifications, which have been introduced in this version of this Recommendation. + +#### Vendor-specific usage + +In this application, the software image ME is flexible, in keeping with the needs of particular vendors and applications. The distinction between fundamental and vendor-specific usage is that the ME ID must not be a value that could be used in the fundamental usage application. That is, the second byte of the ME ID must be neither 0x00 nor 0x01. + +The ONU automatically instantiates as many instances as it is prepared to support. + +- In its vendor-specific usage, the attributes of the software image ME are optional. +- The actions are optional. +- Files may or may not exist in versioned pairs (previous revision, next revision). + +#### Relationships + +A vendor-specific instance of the software image ME represents an externally visible file on the ONU. The content and use of the file are not specified. + +##### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The first byte indicates the physical location of the equipment hosting the software image, either the ONU (0) or a cardholder (1..254). The second byte distinguishes between software image ME instances, and in vendor-specific usage is required to have neither the value 0x00 nor the value 0x01. To facilitate discovery by the OLT, it is suggested that the first byte of the ME ID be 0, and that the second byte be numbered consecutively from 2. (R) (mandatory) (2 bytes) + +**Version:** If this attribute is supported, its meaning is the same as that of the fundamental usage application. (R) (optional) (14 bytes) + +**Is committed:** This attribute indicates whether the associated file is committed (1) or uncommitted (0). Vendor-specific instances may or may not exist in pairs, and may or may not support the concept of a commit. (R) (optional) (1 byte) + +**Is active:** This attribute indicates whether the associated file is active (1) or inactive (0). Vendor-specific instances may or may not support the concept of an active state. (R) (optional) (1 byte) + +- Is valid:** This attribute indicates whether the associated file is valid (1) or invalid (0). Vendor-specific instances may or may not include a way to determine their validity. (R) (optional) (1 byte) +- Product code:** This attribute provides a way for a vendor to indicate product code information on a file. It is a character string, padded with trailing nulls if it is shorter than 25 bytes. (R) (optional) (25 bytes) +- Image hash:** This attribute is an MD5 hash of the software image. It is computed at completion of the end download action. (R) (optional) (16 bytes) + +##### *Actions* + +##### **Get** + +The following actions are available for vendor-specific use, but optional. If the ONU does not support a given action, it should respond with a command not supported result and reason code. + +**Start download:** Initiate a software download sequence. + +**Download section:** Download a section of a file. + +**End download:** Signal the completion of a file download, providing CRC and version information for final verification, if supported. This action causes the file to be stored in the ONU's non-volatile memory. + +NOTE – There is no explicit way to delete a file. It is suggested that the ONU recognize downloading a file of size zero as a delete operation, i.e., a start download command specifying zero image size, followed by an immediate end download, with a zero CRC and also specifying zero image size. + +**Activate image:** Effectuate the file, e.g., by loading its contents into ONU hardware. If appropriate, the hardware or application may be reinitialized. + +**Commit image:** Set the *is committed* attribute value to 1 for the target file ME, if supported. The semantics of this operation are vendor-specific; there is no de-commit action. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Version | | +| 2 | Is committed | | +| 3 | Is active | If an autonomous change to this attribute is associated with an ONU re-boot, the ONU should send the AVC (one for each primary software image instance) after the re-boot. | +| 4 | Is valid | | +| 5 | Product code | | +| 6 | Image hash | | +| 7..16 | Reserved | | + +NOTE – Older implementations of the OMCI may not support these notifications, which have been introduced in this version of this Recommendation. + +### 9.1.5 Cardholder + +The cardholder represents the fixed equipment slot configuration of the ONU. Each cardholder can contain 0 or 1 circuit packs; the circuit pack models equipment information that can change over the lifetime of the ONU, e.g., through replacement. + +One instance of this ME exists for each physical slot in an ONU that has pluggable circuit packs. One or more instances of this ME may also exist in an integrated ONU, to represent virtual slots. Instances of this ME are created automatically by the ONU, and the status attributes are populated according to data within the ONU itself. + +Slot 0 is intended to be used only in an integrated ONU. If an integrated ONU is modelled with a universal slot 0, it is recommended that it does not contain additional (non-zero) virtual slots. A cardholder for virtual slot 0 is recommended. + +There is potential for conflict in the semantics of the expected plug-in unit type, the expected port count and the expected equipment ID, both when the slot is not populated and when a new circuit pack is inserted. The expected plug-in unit type and the plug-in type mismatch alarm are mandatory, although *plug-and-play/unknown* (circuit pack type 255) may be used as a way to minimize their significance. It is recommended that an ONU deny the provisioning of inconsistent combinations of expected equipment attributes. + +When a circuit pack is plugged into a cardholder or when a cardholder is pre-provisioned to expect a circuit pack of a given type, it may trigger the ONU to instantiate a number of MEs and update the values of others, depending on the circuit pack type. The ONU may also delete a variety of other MEs when a circuit pack is reprovisioned to not expect a circuit pack or to expect a circuit pack of a different type. These actions are described in the definitions of the various MEs. + +Expected equipment ID and expected port count are alternate ways to trigger the same pre-provisioning effects. These tools may be useful if an ONU is prepared to accept more than one circuit pack of a given type but with different port counts, or if a circuit pack is a hybrid that matches none of the types in Table 9.1.5-1, but whose identification (e.g., part number) is known. + +#### *Relationships* + +An ONU may contain zero or more instances of the cardholder, each of which may contain an instance of the circuit pack ME. The slot ID, real or virtual, is a fundamental identification mechanism for MEs that bear some relationship to a physical location. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The ONU sets the first byte of this 2 byte identifier to: + +- 0 if the ONU contains pluggable equipment modules +- 1 if the ONU is a single piece of integrated equipment. + +The second byte of this identifier is the slot number. In integrated ONUs, this byte may be used as a virtual slot or set to 0 to indicate a universal pseudo-slot. + +Slot numbering schemes differ among vendors. It is only required that slot numbers be unique across the ONU. Up to 254 equipment slots are supported in the range 1..254 (Note 1). The value 0 is reserved for possible use in an integrated ONU to indicate a universal pseudo-slot. The value 255 is also reserved. (R) (mandatory) (2 bytes) + +NOTE 1 – Some xDSL MEs use the two MSBs of the slot number for other purposes. An ONU that supports these services may have slot limitations or restrictions. + +**Actual plug-in unit type:** This attribute is equal to the type of the circuit pack in the cardholder, or 0 if the cardholder is empty. When the cardholder is populated, this attribute is the same as the type attribute of the corresponding circuit pack ME. Circuit pack types are defined in Table 9.1.5-1. (R) (mandatory) (1 byte) + +The three following attributes permit the OLT to specify its intentions for any future equipped configuration of a slot. Once some or all of these are set, the ONU can proceed to instantiate circuit pack and PPTP MEs, along with other predeterminable MEs, and allow the OLT to create related discretionary MEs, thereby supporting service pre-provisioning. + +**Expected plug-in unit type:** This attribute provisions the type of circuit pack for the slot. For type coding, see Table 9.1.5-1. The value 0 means that the cardholder is not provisioned to contain a circuit pack. The value 255 means that the cardholder is configured for plug-and-play. Upon ME instantiation, the ONU sets this attribute to 0. For integrated interfaces, this attribute may be used to represent the type of interface. (R, W) (mandatory) (1 byte) + +**Expected port count:** This attribute permits the OLT to specify the number of ports it expects in a circuit pack. Prior to provisioning by the OLT, the ONU initializes this attribute to 0. (R, W) (optional) (1 byte) + +**Expected equipment ID:** This attribute provisions the specific type of expected circuit pack. This attribute applies only to ONUs that do not have integrated interfaces. In some environments, this may contain the expected CLEI code. Upon ME instantiation, the ONU sets this attribute to all spaces. (R, W) (optional) (20 bytes) + +**Actual equipment ID:** This attribute identifies the specific type of circuit pack, once it is installed. This attribute applies only to ONUs that do not have integrated interfaces. In some environments, this may include the CLEI code. When the slot is empty or the equipment ID is not known, this attribute should be set to all spaces. (R) (optional) (20 bytes) + +**Protection profile pointer:** This attribute specifies an equipment protection profile that may be associated with the cardholder. Its value is the least significant byte of the ME ID of the equipment protection profile with which it is associated, or 0 if equipment protection is not used. (R) (optional) (1 byte) + +**Invoke protection switch:** The OLT may use this attribute to control equipment protection switching. Code points have the following meaning when set by the OLT: + +- | | | +|---|-----------------------------------------------------------| +| 0 | Release protection switch | +| 1 | Operate protection switch, protect cardholder unspecified | +| 2 | Operate protection switch, use first protect cardholder | +| 3 | Operate protection switch, use second protect cardholder | + +The ONU should deny attempts to switch to an unequipped, defective or already active protection cardholder. + +Upon the get action from the OLT, this attribute should return the current value of the actual protection configuration. Code points are as defined above; the value 1 is never returned. + +When circuit packs that support a PON interface (IF) function are switched, the response should be returned on the same PON that received the command. However, the OLT should also be prepared to accept a response on the redundant PON. (R, W) (optional) (1 byte) + +**Alarm-reporting control (ARC):** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------| +| 1 | Actual type | Actual type of circuit pack in cardholder | +| 2..4 | N/A | | +| 5 | Actual equipment id | Actual equipment ID of circuit pack in cardholder | +| 6..7 | N/A | | +| 8 | ARC | ARC timer expiration | +| 9 | N/A | | +| 10..16 | Reserved | | + +#### **Alarm (Note 2)** + +| Alarm number | Alarm | Description | +|--------------|-------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Plug-in circuit pack missing | Configured circuit pack is not present. If this alarm is active, none of the mismatch alarms are declared. | +| 1 | Plug-in type mismatch alarm | Inserted circuit pack is wrong type | +| 2 | Improper card removal | Circuit pack has been removed without being de-provisioned or administratively locked. This is a redundant alarm that helps the OLT distinguish between transitions from state S2 to state S1 (Figure 9.1.5-1) and transitions from state S4 to state S1. This alarm is sent only when a transition occurs from state S2 to state S1. | +| 3 | Plug-in equipment ID mismatch alarm | Inserted circuit pack has the wrong equipment ID | +| 4 | Protection switch | An autonomous equipment protection switch has occurred. This notification is reported by the protected cardholder. | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific | Not to be standardized | + +NOTE 2 – If no circuit pack is configured or if the cardholder is configured for plug-and-play with no expected equipment ID, no alarms are raised. No cardholder alarms are defined for ONUs with integrated interfaces. + +Figure 9.1.5-1 is a state diagram that describes insertion and removal of a particular circuit pack into/from a cardholder that is provisioned to a specific type or to plug-and-play. + +NOTE 3 – The state diagram is not applicable for ONUs with integrated interfaces. + +![Cardholder state diagram showing states S0 through S9 and S3'. Transitions include actions like 'set expected type', 'remove circuit pack', 'insert circuit pack', 'delete circuit pack', and 'create circuit pack' with associated alarms and AVC conditions. A NOTE explains that secondary MEs shown as auto-created or auto-deleted are appropriate for circuit packs that provide subscriber interface (UNI) functions.](f78d2e126f00fcc5d8d9797ca410cc09_img.jpg) + +**state S3** +Cardholder +actual type: Y +expected type: no circuit pack + +**state S4** +Cardholder +actual type: Y +expected type: X + +**state S3'** +Cardholder +actual type: X +expected type: no circuit pack + +**state S0** +Cardholder +actual type: no circuit pack +expected type: no circuit pack + +**state S1** +Cardholder +actual type: no circuit pack +expected type: X + +**state S2** +Cardholder +actual type: X +expected type: X + +**state S5** +Cardholder +actual type: no circuit pack +expected type: plug-and-play + +**state S6** +Cardholder +actual type: no circuit pack +expected type: plug-and-play + +**state S7** +Cardholder +actual type: X +expected type: plug-and-play + +**state S8** +Cardholder +actual type: X +expected type: plug-and-play + +**state S9** +Cardholder +actual type: Y +expected type: plug-and-play + +**Transitions:** + +- S3 to S4: set expected type = no circuit pack, auto-delete: circuit pack, UNI, PPTP, PQs, Alarm: pluginTypeMismatch off +- S4 to S3: set expected type = X, auto-create: circuit pack, UNI, PPTP, PQs, Alarm: pluginTypeMismatch on +- S3 to S0: remove circuit pack Y, AVC: actual type = no circuit pack +- S0 to S3: insert circuit pack Y, AVC: actual type = Y +- S4 to S1: remove circuit pack Y, Alarm: pluginTypeMismatch off, pluginMissing on, AVC: actual type = no circuit pack +- S1 to S4: insert circuit pack Y, Alarm: pluginTypeMismatch on off, AVC: actual type = Y +- S0 to S1: set expected type = no circuit pack, auto-delete: circuit pack, UNI, PPTP, PQs, Alarm: off +- S1 to S0: set expected type = X, auto-create: circuit pack, UNI, PPTP, PQs, Alarm: pluginMissing on +- S1 to S2: remove circuit pack X, Alarm: improperRemoval on, AVC: actual type = no circuit pack +- S2 to S1: insert circuit pack X, Alarm: improperRemoval off, AVC: actual type = X +- S2 to S3': set expected type = no circuit pack, auto-delete: circuit pack, UNI, PPTP, PQs +- S3' to S2: set expected type = X, auto-create: circuit pack, UNI, PPTP, PQs +- S0 to S5: set expected type = plug-and-play +- S5 to S0: set expected type = no circuit pack +- S5 to S6: delete circuit pack X, delete: circuit pack, auto-delete: UNI, PPTP, PQs +- S6 to S5: create circuit pack X, create: circuit pack, auto-create: UNI, PPTP, PQs +- S6 to S7: remove circuit pack X, AVC: actual type = no circuit pack +- S7 to S6: insert circuit pack X, AVC: actual type = X +- S7 to S5: delete circuit pack X, delete: circuit pack, auto-delete: UNI, PPTP, PQs +- S5 to S8: insert circuit pack X, AVC: actual type = X +- S8 to S5: remove circuit pack X, AVC: actual type = no circuit pack +- S8 to S9: create circuit pack X, create: circuit pack, auto-create: UNI, PPTP, PQs +- S9 to S8: insert circuit pack Y, Alarm: pluginTypeMismatch on, AVC: actual type = Y +- S9 to S6: remove circuit pack Y, Alarm: pluginTypeMismatch off, AVC: actual type = no circuit pack + +**NOTE** – The secondary MEs shown as auto-created or auto-deleted are appropriate for circuit packs that provide subscriber interface (UNI) functions. Other types of circuit packs have different secondary MEs, or no secondary MEs according to the definition of the MEs and the function of the circuit pack. + +Cardholder state diagram showing states S0 through S9 and S3'. Transitions include actions like 'set expected type', 'remove circuit pack', 'insert circuit pack', 'delete circuit pack', and 'create circuit pack' with associated alarms and AVC conditions. A NOTE explains that secondary MEs shown as auto-created or auto-deleted are appropriate for circuit packs that provide subscriber interface (UNI) functions. + +G.988(12)\_F9.1.5-1 + +**Figure 9.1.5-1 – Cardholder state diagram** + +Some of the following circuit pack types are obsolete in current applications. Their code points and definitions are reserved for backward compatibility, but in the interest of brevity, they are not listed. + +**Table 9.1.5-1 – Plug-in unit types** + +| Coding | Content | Description | +|--------|--------------------------------------|----------------------------------------------------------------------------------------------------------------| +| 0 | No LIM | Default value | +| 1..12 | See [ITU-T G.983.2] | Various ATM based UNIs | +| 13 | C1.5 (DS1) | 1.544 Mbit/s local (T-interface) module | +| 14 | C2.0 (E1) | 2.048 Mbit/s local (T-interface) module | +| 15 | C6.3 (J2) | 6.312 Mbit/s local (T-interface) module | +| 16 | C-DS1/E1 | Configurable DS1/E1 module | +| 17 | C-DS1/E1/J1 | Configurable DS1/E1/J1 module | +| 18..21 | See [ITU-T G.984.4] | Various CES services | +| 22 | 10BASE-T | IEEE 802.3 10BASE-T Ethernet LAN IF | +| 23 | 100BASE-T | IEEE 802.3 100BASE-T Ethernet LAN IF | +| 24 | 10/100 BASE-T | IEEE 802.3 10/100 BASE-T Ethernet LAN IF | +| 25..27 | See [ITU-T G.983.2] | Various non-Ethernet LAN technologies | +| 28 | C1.5 (J1) | 1.544 Mbit/s local (T-interface) module | +| 29..31 | See [ITU-T G.984.4] | Various ATM interfaces | +| 32 | POTS | Plain old telephony service | +| 33 | ISDN-BRI | ISDN basic rate interface (deprecated) | +| 34 | Gigabit optical Ethernet | Any IEEE 802.3 Gigabit Ethernet optical IF | +| 35 | xDSL | xDSL IF | +| 36 | SHDSL | SHDSL IF | +| 37 | VDSL | VDSL IF [ITU-T G.993.1] | +| 38 | Video service | Video module | +| 39 | LCT | Local craft terminal interface | +| 40 | 802.11 | Wireless interface [IEEE 802.11] | +| 41 | xDSL/POTS | Combination xDSL and POTS interfaces | +| 42 | VDSL/POTS | Combination VDSL [ITU-T G.993.1] and POTS interfaces | +| 43 | Common equipment | Circuit packs such as removable power supply modules or ONU controllers | +| 44 | Combined video UNI and PON interface | Circuit pack that combines both functions | +| 45 | Mixed services equipment | Circuit pack with several types of ANI or UNI. Suggested for use with the port-mapping package managed entity. | +| 46 | MoCA | MoCA | +| 47 | 10/100/1000BASE-T | IEEE 802.3 10/100/1000 BASE-T LAN Ethernet LAN interface | +| 48 | VEIP | Virtual Ethernet interface point | +| 49 | 10G GBASE-T Ethernet | IEEE 802.3 10G BASE-T Ethernet LAN interface | +| 50 | 2.5GBASE-T Ethernet | IEEE 802.3 2.5GBASE-T Ethernet LAN interface | +| 51 | 5GBASE-T Ethernet | IEEE 802.3 5GBASE-T Ethernet LAN interface | +| 52 | 25GBASE-T Ethernet | IEEE 802.3 25GBASE-T Ethernet LAN interface | +| 53 | 40GBASE-T Ethernet | IEEE 802.3 40GBASE-T Ethernet LAN interface | + +**Table 9.1.5-1 – Plug-in unit types** + +| Coding | Content | Description | +|---------------|-----------------------|--------------------------------------------------------| +| 54 | 1000BASE-LX | IEEE 802.3 1000BASE-LX Ethernet optical interface | +| 55 | 1000BASE-SX | IEEE 802.3 1000BASE-SX Ethernet optical interface | +| 56 | 10GBASE-SR | IEEE 802.3 10GBASE-SR optical interface | +| 57 | 10GBASE-LX4 | IEEE 802.3 10GBASE-LX4 optical interface | +| 58 | 10GBASE-LRM | IEEE 802.3 10GBASE-LRM optical interface | +| 59 | 10GBASE-LR | IEEE 802.3 10GBASE-LR optical interface | +| 60 | 10GBASE-ER | IEEE 802.3 10GBASE-ER optical interface | +| 61 | 10GBASE-SW | IEEE 802.3 10GBASE-SW optical interface | +| 62 | 10GBASE-LW | IEEE 802.3 10GBASE-LW optical interface | +| 63 | 10GBASE-EW | IEEE 802.3 10GBASE-EW optical interface | +| 64 | 25GBASE-SR | IEEE 802.3 25GBASE-SR optical interface | +| 65 | 40GBASE-SR4 | IEEE 802.3 40GBASE-SR optical interface | +| 66 | 40GBASE-LR4 | IEEE 802.3 40GBASE-LR optical interface | +| 67 | 40GBASE-ER4 | IEEE 802.3 40GBASE-ER4 optical interface | +| 68 | Multi-Rate-10GBASE-T | Any IEEE 802.3 10GBASE-T with XGMII and GMII interface | +| 69 | 10G Optical Interface | Any IEEE 802.3 10G optical interface | +| 70 | 40G Optical Interface | Any IEEE 802.3 40G optical interface | +| 71 | G.fast | ITU-T G.9701 G.fast | +| 72 | 25G Optical Interface | Any IEEE 802.3 25G optical interface | +| 73 | 50G Optical Interface | Any IEEE 802.3 50G optical interface | +| 74 | 25GBASE-LR | IEEE 802.3 25GBASE-LR optical interface | +| 75 | 25GBASE-ER | IEEE 802.3 25GBASE-ER optical interface | +| 76 | 50GBASE-SR | IEEE 802.3 50GBASE-SR optical interface | +| 77 | 50GBASE-FR | IEEE 802.3 50GBASE-FR optical interface | +| 78 | 50GBASE-LR | IEEE 802.3 50GBASE-LR optical interface | +| 79 | 50GBASE-ER | IEEE 802.3 50GBASE-ER optical interface | +| 80 | 10GBASE-BR10 | IEEE 802.3 10GBASE-BR10 optical interface | +| 81 | 10GBASE-BR20 | IEEE 802.3 10GBASE-BR20 optical interface | +| 82 | 10GBASE-BR40 | IEEE 802.3 10GBASE-BR40 optical interface | +| 83 | 25GBASE-BR10 | IEEE 802.3 25GBASE-BR10 optical interface | +| 84 | 25GBASE-BR20 | IEEE 802.3 25GBASE-BR20 optical interface | +| 85 | 25GBASE-BR40 | IEEE 802.3 25GBASE-BR40 optical interface | +| 86 | 50GBASE-BR10 | IEEE 802.3 50GBASE-BR10 optical interface | +| 87 | 50GBASE-BR20 | IEEE 802.3 50GBASE-BR20 optical interface | +| 88 | 50GBASE-BR40 | IEEE 802.3 50GBASE-BR40 optical interface | +| 89..191 | Reserved | | +| 192..223 | Vendor-specific | Reserved for vendor use, not to be standardized | +| 224..226 | Reserved | | + +**Table 9.1.5-1 – Plug-in unit types** + +| Coding | Content | Description | +|---------------|--------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------| +| 227 | HSP50G50 | HSP interface with 49.7664 Gbit/s downstream, 49.7664 Gbit/s upstream | +| 228 | HSP50G25 | HSP interface with 49.7664 Gbit/s downstream, 24.8832 Gbit/s upstream | +| 229 | HSP50G12 | HSP interface with 49.7664 Gbit/s downstream, 12.4416 Gbit/s upstream | +| 230 | Multi-PON | Any ITU-T PON type. This codepoint is applicable to circuit pack and cardholder ME | +| 231 | PtP WDM PON line rate class 1 | PtP WDM PON interface, the relative nominal line rates see Table A.1 in Amd.1 to [ITU-T G.989.2] | +| 232 | PtP WDM PON line rate class 2 | PtP WDM PON interface, the relative nominal line rates see Table A.1 in Amd.1 to [ITU-T G.989.2] | +| 233 | PtP WDM PON line rate class 3 | PtP WDM PON interface, the relative nominal line rates see Table A.1 in Amd.1 to [ITU-T G.989.2] | +| 234 | TWDM10G2 | ITU-T G.989 TWDM-PON interface, 9.95328 G downstream/2.48832 upstream | +| 235 | TWDM10G10 | ITU-T G.989 TWDM-PON interface, 9.95328 G downstream/9.95328 upstream | +| 236 | TWDM2G2 | ITU-T G.989 TWDM-PON interface, 2.48832 G downstream/2.48832 G upstream | +| 237 | XG-PON10G2488 | XG-PON interface, 10G downstream and 2.488G upstream | +| 238 | XG-PON10G10 | XG-PON interface, 10G downstream and 10G upstream | +| 239 | Mid-span PON reach extender UNI | The UNI of a mid-span PON reach extender | +| 240 | Mid-span PON reach extender ANI | The ANI of a mid-span PON reach extender | +| 241 | Mid-span PON reach extender upstream optical amplifier | Upstream optical amplifier 1 270 nm or 1 310 nm | +| 242 | Mid-span PON 2488/1244 reach extender downstream optical amplifier | 2488/1244 1 490 nm downstream optical amplifier with no corresponding RE ANI-G | +| 243..247 | See [ITU-T G.984.4] | G-PON interfaces of diverse rates | +| 248 | GPON24881244 | GPON interface, 2 488 Mbit/s downstream and 1 244 Mbit/s upstream | +| 249..254 | See [ITU-T G.983.2] and [ITU-T G.984.4] | G-PON and B-PON (broadband passive optical network) interfaces of diverse rates | +| 255 | Plug-and-play/Unknown | Plug-and-play (for the cardholder managed entity only). Unrecognized module (for the circuit pack managed entity only) | + +### 9.1.6 Circuit pack + +This ME models a real or virtual circuit pack that is equipped in a real or virtual ONU slot. For ONUs with integrated interfaces, this ME may be used to distinguish available types of interfaces (the port-mapping package is another way). + +For ONUs with integrated interfaces, the ONU automatically creates an instance of this ME for each instance of the virtual cardholder ME. The ONU also creates an instance of this ME when the OLT provisions the cardholder to expect a circuit pack, i.e., when the OLT sets the expected plug-in unit type or equipment ID of the cardholder to a circuit pack type, as defined in Table 9.1.5-1. The ONU also creates an instance of this ME when a circuit pack is installed in a cardholder whose expected plug-in unit type is 255 = plug-and-play, and whose equipment ID is not provisioned. Finally, when the cardholder is provisioned for plug-and-play, an instance of this ME can be created at the request of the OLT. + +The ONU deletes an instance of this ME when the OLT de-provisions the circuit pack (i.e., when the OLT sets the expected plug-in unit type or equipment ID of the cardholder to 0 = no LIM). The ONU also deletes an instance of this ME on request of the OLT if the expected plug-in unit type attribute of the corresponding cardholder is equal to 255, plug-and-play, and the expected equipment ID is blank (a string of all spaces). ONUs with integrated interfaces do not delete circuit pack instances. + +NOTE – Creation and deletion by the OLT is retained for backward compatibility. + +#### *Relationships* + +An instance of this ME is contained by an instance of the cardholder ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value is the same as that of the cardholder ME containing this circuit pack instance. (R, set-by-create if applicable) (mandatory) (2 bytes) + +**Type:** This attribute identifies the circuit pack type. This attribute is a code as defined in Table 9.1.5-1. The value 255 means unknown or undefined, i.e., the inserted circuit pack is not recognized by the ONU or is not mapped to an entry in Table 9.1.5-1. In the latter case, the equipment ID attribute may contain inventory information. Upon autonomous ME instantiation, the ONU sets this attribute to 0 or to the type of the circuit pack that is physically present. (R, set-by-create if applicable) (mandatory) (1 byte) + +**Number of ports:** This attribute is the number of access ports on the circuit pack. If the port-mapping package is supported for this circuit pack, this attribute should be set to the total number of ports of all types. (R) (optional) (1 byte) + +**Serial number:** The serial number is expected to be unique for each circuit pack, at least within the scope of the given vendor. Note that the serial number may contain the vendor ID or version number. For integrated ONUs, this value is identical to the value of the serial number attribute of the ONU-G ME. Upon creation in the absence of a physical circuit pack, this attribute comprises all spaces. (R) (mandatory) (8 bytes) + +**Version:** This attribute is a string that identifies the version of the circuit pack as defined by the vendor. The value 0 indicates that version information is not available or applicable. For integrated ONUs, this value is identical to the value of the version attribute of the ONU-G ME. Upon creation in the absence of a physical circuit pack, this attribute comprises all spaces. (R) (mandatory) (14 bytes) + +**Vendor ID:** This attribute identifies the vendor of the circuit pack. For ONUs with integrated interfaces, this value is identical to the value of the vendor ID attribute of the ONU-G ME. Upon creation in the absence of a physical circuit pack, this attribute comprises all spaces. (R) (optional) (4 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the circuit pack is capable of performing its function. Valid values are enabled (0), disabled (1) and unknown (2). Pending completion of initialization and self-test on an installed circuit pack, the ONU sets this attribute to 2. (R) (optional) (1 byte) + +**Bridged or IP ind:** This attribute specifies whether an Ethernet interface is bridged or derived from an IP router function. + +- 0 Bridged +- 1 IP router +- 2 Both bridged and IP router functions + +(R, W) (optional, only applicable for circuit packs with Ethernet interfaces) (1 byte) + +**Equipment ID:** This attribute may be used to identify the vendor's specific type of circuit pack. In some environments, this attribute may include the CLEI code. Upon ME instantiation, the ONU sets this attribute to all spaces or to the equipment ID of the circuit pack that is physically present. (R) (optional) (20 bytes) + +**Card configuration:** This attribute selects the appropriate configuration of configurable circuit packs. Table 9.1.5-1 specifies two configurable card types: C-DS1/E1 (code 16), and C-DS1/E1/J1 (code 17). Values are indicated below for the allowed card types and configurations. + +| Card Type | Configuration | Value | +|-------------|---------------|-------| +| C-DS1/E1 | DS1 | 0 | +| | E1 | 1 | +| C-DS1/E1/J1 | DS1 | 0 | +| | E1 | 1 | +| | J1 | 2 | + +Upon autonomous instantiation, this attribute is set to 0. (R, W, set-by-create if applicable) (mandatory for configurable circuit packs) (1 byte) + +**Total T-CONT buffer number:** This attribute reports the total number of T-CONT buffers associated with the circuit pack. Upon ME instantiation, the ONU sets this attribute to 0 or to the value supported by the physical circuit pack. (R) (mandatory for circuit packs that provide a traffic scheduler function) (1 byte) + +**Total priority queue number:** This value reports the total number of priority queues associated with the circuit pack. Upon ME instantiation, the ONU sets the attribute to 0 or to the value supported by the physical circuit pack. (R) (mandatory for circuit packs that provide a traffic scheduler function) (1 byte) + +**Total traffic scheduler number:** This value reports the total number of traffic schedulers associated with the circuit pack. The ONU supports null function, strict priority scheduling and WRR from the priority control, and guarantee of minimum rate control points of view. If the circuit pack has no traffic scheduler, this attribute should be absent or have the value 0. Upon ME instantiation, the ONU sets the attribute to 0 or to the value supported by the physical circuit pack. (R) (mandatory for circuit packs that provide a traffic scheduler function) (1 byte) + +**Power shed override:** This attribute allows ports to be excluded from the power shed control defined in clause 9.1.7. It is a bit mask that takes port 1 as the MSB; a bit value of 1 marks the corresponding port to override the power shed timer. For hardware that cannot shed power per port, this attribute is a slot override rather than a port override, with any non-zero port value causing the entire circuit pack to override power shedding. (R, W) (optional) (4 bytes) + +#### *Actions* + +Get, set + +Create, delete: Optional, only when plug-and-play is supported. + +Reboot: Reboot the circuit pack. + +Test: Test the circuit pack (optional). The test action may be used either to perform equipment diagnostics or to measure parameters, such as received optical power, video output level and battery voltage. Test and test result messages are defined in Annex A. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..6 | N/A | | +| 7 | Op state | Operational state change | +| 8..14 | N/A | | +| 15..16 | Reserved | | + +#### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Equipment alarm | A failure on an internal interface or failed self-test | +| 1 | Powering alarm | Fuse failure or failure of DC/DC converter | +| 2 | Self-test failure | Failure of circuit pack autonomous self-test | +| 3 | Laser end of life | Failure of transmit laser imminent | +| 4 | Temperature yellow | No service shutdown at present, but the circuit pack is operating beyond its recommended range. | +| 5 | Temperature red | Service has been shut down to avoid equipment damage. The operational state of the affected PPTPs indicates the affected services. | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.1.7 ONU power shedding + +This ME models the ONU's ability to shed services when the ONU goes into battery operation mode after AC power failure. Shedding classes are defined in the following table, which may span multiple circuit pack types. This feature works in conjunction with the power shed override attribute of the circuit pack ME, which can selectively prevent power shedding of priority ports. + +An ONU that supports power shedding automatically creates an instance of this ME. + +The following table defines the binding of shedding class and PPTP type. The coding is taken from Table 9.1.5-1. In the case of hybrid circuit pack types, multiple shedding classes may affect a circuit pack if the hardware is capable of partial power shedding. + +An ONU may choose to model its ports with the port-mapping package of clause 9.1.8, rather than with real or virtual circuit packs. In this case, power shedding pertains to individual PPTPs (listed in column 2 of the table). + +| Shedding class | PPTP type | Coding | Content | +|----------------------------|------------------|----------|----------------------------------------------------| +| ATM | ATM PPTP | 1..12 | Various ATM UNIs | +| CES | CES PPTP | 13 | C1.5 (DS1) | +| | | 14 | C2.0 (E1) | +| | | 15 | C6.3 (J2) | +| | | 16 | C-DS1/E1 | +| | | 17 | C-DS1/E1/J1 | +| Data | Ethernet PPTP | 22 | 10BASE-T | +| | | 23 | 100BASE-T | +| | | 24 | 10/100 BASE-T | +| Frame | Unspecified | 25..27 | Non-Ethernet LANs | +| CES | CES PPTP | 28 | C1.5 (J1) | +| Sdh-sonet | Sdh-sonet | 29..31 | ATM sdh-sonet interfaces | +| Voice | POTS PPTP | 32 | POTS | +| | ISDN PPTP | 33 | ISDN BRI (deprecated) | +| Data | Ethernet PPTP | 34 | Gigabit optical Ethernet | +| DSL | xDSL PPTP | 35 | xDSL | +| | SHDSL | 36 | SHDSL | +| | VDSL PPTP | 37 | ITU-T G.993.1 VDSL | +| N/A | Video UNI | 38 | Radio frequency (RF) video service | +| N/A | LCT PPTP | 39 | Local craft terminal | +| Data | IEEE 802.11 PPTP | 40 | Wireless | +| Voice (DSL may also apply) | xDSL + POTS | 41 | xDSL/POTS | +| | VDSL + POTS | 42 | ITU-T G.993.1 VDSL/POTS | +| N/A | Unspecified | 43 | Common equipment | +| | Unspecified | 44 | Combined video, PON | +| | Unspecified | 45 | Mixed services (Power shedding based on port type) | +| Data | MoCA PPTP | 46 | MoCA | +| Data | Ethernet PPTP | 47 | 10/100/1000 BASE-T | +| | | 49 | 10G Ethernet | +| N/A | PON PPTP | 237..238 | XG-PON ANIs | +| Video overlay | Video ANI PPTP | | | +| Video return | Video RPD | | | + +#### Relationships + +One instance of this ME is associated with the ONU ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Restore power timer reset interval:** The time delay, in seconds, before resetting the power-shedding timers after full power restoration. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (2 bytes) + +For each class of service (CoS), an interval attribute is defined below. The value 0 disables power shedding, while the value 1 enables immediate power shedding, i.e., as soon as AC power fails. Other values specify the time, in seconds, to keep the service active after AC failure before shutting them down and shedding power. Upon ME instantiation, the ONU sets each of the interval attributes to 0. + +**Data class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Voice class shedding interval:** This attribute only pertains to voice services that terminate on the ONU and are under the management control of the OMCI. +(R, W) (mandatory) (2 bytes) + +**Video overlay class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Video return class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Digital subscriber line (DSL) class shedding interval:** (R, W) (mandatory) (2 bytes) + +**ATM class shedding interval:** (R, W) (mandatory) (2 bytes) + +**CES class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Frame class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Sdh-sonet class shedding interval:** (R, W) (mandatory) (2 bytes) + +**Shedding status:** Binary indication of power-shedding status for each shedding class. If this 2 byte field is depicted 0b ABCD EFGH IJKL MNOP, its bits are assigned as follows- + +- A Data class +- B Voice class +- C Video overlay class +- D Video return class +- E DSL class +- F ATM class +- G CES class +- H Frame class +- I Sdh-sonet class +- J..P Reserved and set to 0 + +The ONU sets each bit to 1 when power shedding is active, and clears it to 0 when the service is restored. (R) (optional) (2 bytes) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------------------------| +| 1..10 | N/A | | +| 11 | Shedding status | State change of a shedding function | +| 12..16 | Reserved | | + +### 9.1.8 Port-mapping package + +NOTE – In [ITU-T G.984.4], this ME is called a port-mapping package-G. + +This ME provides a way to map a heterogeneous set of PPTPs (ports) to a parent equipment, which may be a cardholder or the ONU itself. It could be useful, for example, if a single plug-in circuit pack contained a PON ANI as port 1, a video UNI as port 2, and a craft UNI as port 3. Another application + +of the port-mapping package is the case where more than one UNI or ANI ME is associated with a single physical port, for example, the RE ANI and downstream amplifier. This ME also provides an option for an integrated ONU to represent its ports without the use of virtual cardholders and VC packs. + +If the port-mapping package is supported for the ONU as a whole, it is automatically created by the ONU. If the port-mapping package is supported for plug-in circuit packs, it is created and destroyed by the ONU when the corresponding circuit pack is installed or pre-provisioned in a cardholder. + +The port list attributes specify ports 1..64 sequentially. Each port list is a sequence of ME types, as defined in Table 11.2.4-1. These ME type codes define what kind of PPTP or ANI corresponds to the specific port number. For example, for a circuit pack with 4 POTS ports, 2 xDSL ports, and 1 video UNI port, numbered sequentially in that order, the attributes would be coded: + +Max ports: 7 +Port list 1: 53, 53, 53, 53, 98, 98, 82, 0 +Port list 2..8: All zero + +#### *Relationships* + +A port-mapping package may be contained by an ONU-G or a cardholder. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ONU-G or cardholder. (R) (mandatory) (2 bytes) + +**Max ports:** This attribute indicates the largest port number contained in the port list attributes. Ports are numbered from 1 to this maximum, possibly with embedded 0 entries, but no port may exist beyond the maximum. (R) (mandatory) (1 byte) + +Each of the following attributes is a list of 8 ports, in increasing port number sequence. Each list entry is a 2 byte field containing the ME type of the UNI or ANI corresponding to the port number. ME types are defined in Table 11.2.4-1. Placeholders for non-existent port numbers are indicated with the value 0. + +**Port list 1:** (R) (mandatory) (16 bytes) + +**Port list 2:** (R) (optional) (16 bytes) + +**Port list 3:** (R) (optional) (16 bytes) + +**Port list 4:** (R) (optional) (16 bytes) + +**Port list 5:** (R) (optional) (16 bytes) + +**Port list 6:** (R) (optional) (16 bytes) + +**Port list 7:** (R) (optional) (16 bytes) + +**Port list 8:** (R) (optional) (16 bytes) + +**Combined port table:** This attribute permits the implicit linking of multiple port-level MEs to a single physical port. For example, a single physical port may be linked to both an RE ANI-G and an RE downstream amplifier, as illustrated in Figure 8.2.10-4. The combination of RE ANI-G and RE downstream amplifier cannot be directly represented in the port list attributes. + +Each row of the combined port table comprises the following fields. + +| Field name | Size, bytes | Description | +|-------------------|-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Physical port | 1 | Duplicates are allowed.
The corresponding physical port in the port list attribute should be 0. | +| Equipment type 1 | 2 | ME type 1, from Table 11.2.4-1. The first equipment type in the list is understood to be the master (in the first row of the table, in the case of duplicate physical ports). The administrative state, operational state and ARC attributes of the master override the corresponding attributes of secondary MEs. | +| ... | 2 | ... secondary MEs that share the physical port | +| Equipment type 12 | 2 | Secondary ME type 12 | + +As many as 12 ME types can be associated with a given physical port, and even more by duplicating the physical port field. (R) (optional) ( $N$ rows \* 25 bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### 9.1.9 Equipment extension package + +This ME supports optional extensions to circuit pack MEs. If the circuit pack supports these features, the ONU creates and deletes this ME along with its associated real or virtual circuit pack. + +#### *Relationships* + +An equipment extension package may be contained by an ONU-G or cardholder. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ONU-G or cardholder. (R) (mandatory) (2 bytes) + +**Environmental sense:** This attribute provisions an ONU that supports external sense points, e.g., physical security detectors at an enclosure. Each pair of bits is defined as follows. + +- 00 Sense point disabled (default) +- 01 Report contact closure +- 10 Report contact open +- 11 Sense point disabled (same as 00) + +If the byte is represented in binary as 0B hhgg ffee ddoc bbaa, bits hh correspond to sense point 1, while bits aa correspond to sense point 8. (R, W) (optional) (2 bytes) + +NOTE – Some specific sense point applications are already defined on the ONU-G ME. It is the vendor's choice how to configure and report sense points that appear both generically and specifically. + +**Contact closure output:** This attribute provisions an ONU that supports external contact closure outputs, e.g., sump pump or air conditioner activation at an ONU enclosure. A contact point is said to be released when it is not energized. Whether this corresponds to an open or a closed electrical circuit depends on the ONU's wiring options. Upon ONU initialization, all contact points should go to the released state. + +If the byte is represented in binary as 0B hhgg ffee ddoc bbaa, bits hh correspond to contact output point 1, while bits aa correspond to contact output point 8. + +On write, the bits of this attribute have the following meaning. + +0x No change to contact output point state + +10 Release contact output point + +11 Operate contact output point + +On read, the left bit in each pair should be set to 0 at the ONU and ignored at the OLT. The right bit indicates a released output point with 0 and an operated contact point with 1. (R, W) (optional) (2 bytes) + +#### Actions + +Get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------------------| +| 0 | Reserved | | +| 1 | Sense point 1 | Environmental sense point 1 active | +| 2 | Sense point 2 | Environmental sense point 2 active | +| 3 | Sense point 3 | Environmental sense point 3 active | +| 4 | Sense point 4 | Environmental sense point 4 active | +| 5 | Sense point 5 | Environmental sense point 5 active | +| 6 | Sense point 6 | Environmental sense point 6 active | +| 7 | Sense point 7 | Environmental sense point 7 active | +| 8 | Sense point 8 | Environmental sense point 8 active | +| 9..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.1.10 Protection data + +This ME models the capability and parameters of PON protection. An ONU that supports PON protection automatically creates one instance of this ME. A chassis-based RE could have the capability of protecting a number of PONs, possibly by way of circuit packs configured in arbitrary (rather than predefined) slots. Protection data MEs in a multi-PON RE may therefore be auto-created or created by the OLT, depending on the RE's architecture, and the ANI-G pointers may be either populated by the ONU itself (read-only) or configured by the OLT (RWSC). Likewise, the nature of protection may be set read-only by the ONU's architecture or may be settable by the OLT. + +NOTE 1 – Equipment protection is modelled with the equipment protection profile and cardholder MEs. + +NOTE 2 – For ONUs that implement RE functions, this ME can be used to describe OMCI protection, RE interface R/S' protection, or both. For R/S' protection, the protection type must be 1:1 without extra traffic, because the switching is done on a link-by-link basis, and the protection link is in cold standby mode. The instance that pertains to OMCI protection has ME ID = 0. + +#### *Relationships* + +One instance of this ME is associated with two instances of the ANI-G, RE ANI-G or RE upstream amplifier. One of the ANI MEs represents the working side; the other represents the protection side. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. If there is more than one protection data ME, they are numbered in ascending order from 0. (R, set-by-create if applicable) (mandatory) (2 bytes) + +**Working ANI-G pointer:** This attribute points to the ANI-G, RE ANI-G or RE upstream amplifier ME that represents the working side of a protected PON. (R, W if applicable, set-by-create if applicable) (mandatory) (2 bytes) + +NOTE 3 – It is possible, and indeed likely, that an ANI-G will have the same ME ID as the RE ANI-G or even the RE upstream amplifier that supports its physical PON interface. The ANI-G represents the embedded ONU that terminates the OMCC. Since it is not expected that protection of management communications will be implemented independently from protection of the optical layer, the ambiguity is not expected to cause a problem. + +**Protection ANI-G pointer:** This attribute points to the ANI-G, RE ANI-G or RE upstream amplifier ME that represents the protection side of a protected PON. (R, W if applicable, set-by-create if applicable) (mandatory) (2 bytes) + +**Protection type:** This attribute indicates the type of PON protection. Valid values are: + +- 0 1+1 protection +- 1 1:1 protection without extra traffic +- 2 1:1 protection with ability to support extra traffic + +(R, W if applicable, set-by-create if applicable) (mandatory) (1 byte) + +**Revertive ind:** This attribute indicates whether protection is revertive (1) or non-revertive (0). (R, W if applicable, set-by-create if applicable) (mandatory) (1 byte) + +**Wait to restore time:** This attribute specifies the time, in seconds, to wait after a fault clears before switching back to the working path. Upon ME instantiation, the ONU sets this attribute to 3 s. (RWSC if applicable) (mandatory) (2 bytes) + +**Switching guard time:** This attribute specifies the time, in milliseconds, to wait after the detection of a fault before performing a protection switch. Specification of a default value for this attribute is outside the scope of this Recommendation, as it is normally handled through supplier-operator negotiations. (RWSC if applicable) (optional) (2 bytes) + +#### *Actions* + +Get, set + +If applicable: create, delete + +#### *Notifications* + +None. + +### 9.1.11 Equipment protection profile + +This ME supports equipment protection. There can be as many as two protection slots protecting as many as eight working slots. Each of the working and protect cardholder MEs should refer to the equipment protection profile that defines its protection group. Instances of this ME are created and deleted by the OLT. + +An ONU should deny pre-provisioning that would create impossible protection groupings because of slot or equipment incompatibilities. In the same way, the ONU should deny creation or addition to protection groups that cannot be supported by the current equipped configuration. Even so, an inconsistent card type alarm is defined, for example, to cover the case of a plug-and-play circuit pack installed in a protection group cardholder that cannot support it. + +#### *Relationships* + +An instance of this object points to the working and protect cardholders, which in turn point back to this ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The first byte is 0. The second byte is assigned by the OLT, and must be unique and non-zero. (R, set-by-create) (mandatory) (2 bytes) + +**Protect slot 1, Protect slot 2:** This pair of attributes describes the protecting cardholder entities in an equipment protection group. There can be one or two protecting entities. + +0 Undefined entry (default), a place-holder if there are fewer than two protecting entities in the protection group. + +1..254 Slot number of the protecting circuit pack. + +(RWSC) (protect slot 1 mandatory, protect slot 2 optional) (1 byte \* 2 attributes) + +**Working slot 1, Working slot 2, Working slot 3, Working slot 4, Working slot 5,** + +**Working slot 6, Working slot 7, Working slot 8:** This group of attributes describes the working cardholder entities in an equipment protection group. There can be up to eight working entities. + +0 Undefined entry (default), a place-holder if there are fewer than eight working entities in the protection group. + +1..254 Slot number of the working circuit pack. + +(RWSC) (working slot 1 mandatory, other working slots optional) (1 byte \* 8 attributes) + +**Protect status 1, Protect status 2:** This pair of attributes indicates whether each protection cardholder is currently protecting another cardholder, and if so, which one. + +0 Not protecting any other cardholder. + +1..254 Slot number of the working cardholder currently being protected by this ME. + +(R) (mandatory) (1 byte \* 2 attributes) + +**Revertive ind:** This attribute specifies whether equipment protection is revertive. The default value 0 indicates revertive switching; any other value indicates non-revertive switching. (RWSC) (optional) (1 byte) + +**Wait to restore time:** This attribute specifies the time, in minutes, during which a working equipment must be free of error before a revertive switch occurs. It defaults to 0. (RWSC) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +##### **Alarm** + +| Alarm number | Alarm | Description | +|---------------------|------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Inconsistent card type | The expected or actual circuit pack type in a slot is incapable of participating in the equipment protection group, either because it is not subject to equipment protection or because its type or equipment ID differs from that previously defined for the other cardholders of the group. When possible, the ONU should deny provisioning attempts that would create incompatibilities, for example, in the case of plug-and-play, it may not be possible to forestall the inconsistency. | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.1.12 ONU remote debug** + +This ME is used to send vendor-specific debug commands to the ONU and receive vendor-specific replies back for processing on the OLT. This allows for the remote debugging of an ONU that may not be accessible by other means. The command format may have two modes, one being text and the other free format. In text format, both the command and reply are ASCII strings, but are otherwise unconstrained. In free format, the content and format of command and reply are vendor-specific. + +An ONU that supports remote debugging automatically creates an instance of this ME. It is not reported during an MIB upload. + +#### *Relationships* + +One instance of this ME is associated with the ONU ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Command format:** This attribute defines the format of the command and reply attributes. The value 0 defines ASCII string format, while 1 specifies free format. (R) (mandatory) (1 byte) + +**Command:** This attribute is used to send a command to the ONU. The format of the command is defined by the command format. If the format is ASCII string, the command should be null terminated unless the string is exactly 25 bytes long. The action of setting this attribute should trigger the ONU to discard any previous command reply information and execute the current debugging command. (W) (mandatory) (25 bytes) + +**Reply table:** This attribute is used to pass reply information back to the OLT. Its format is defined by the command format attribute. The get, get next action sequence must be used with this attribute, since its size is unspecified. (R) (mandatory) (N bytes) + +#### *Actions* + +Get, get next, set + +#### Notifications + +None. + +### 9.1.13 ONU-E + +This ME represents a point-to-point gigabit Ethernet-fed ONU as equipment, as defined in [ITU-T G.986]. The ONU automatically creates an instance of this ME. It assigns values to read-only attributes according to data within the ONU itself. + +#### Relationships + +In ITU-T G.986 applications, all other MEs in this Recommendation are related directly or indirectly to the ONU-E entity. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (R) (mandatory) (2 bytes) + +**Vendor ID:** This attribute identifies the vendor of the ONU. Both the code set for the vendor\_ID specified in [ATIS-0300220] and organizationally unique identifier (OUI) specified in clause 9 of [IEEE 802] may be applied to this attribute. + +When the code set for the vendor\_ID specified in [ATIS-0300220] is applied to this attribute, the four characters are mapped into the 4 byte field by concatenating the ASCII/ANSI character codes. + +When the OUI is applied to this attribute, the three characters are mapped into the 4 byte field with 0xFF assigned to the first octet. + +(R) (mandatory) (4 bytes) + +| Octet | Content | | +|-------|-----------------------------|--------------------| +| | Vendor_ID in [ATIS-0300220] | OUI in [IEEE 802] | +| 1 | First byte of Vendor_ID | 0xFF | +| 2 | Second byte of Vendor_ID | First byte of OUI | +| 3 | Third byte of Vendor_ID | Second byte of OUI | +| 4 | Fourth byte of Vendor_ID | Third byte of OUI | + +**Version:** This attribute identifies the version of the ONU as defined by the vendor. The character value "0" indicates that version information is not available or applicable. (R) (mandatory) (14 bytes) + +**Serial number:** The serial number is unique for each ONU. It is defined by the vendor. The character value "0" indicates that serial number information is not available or applicable. (R) (mandatory) (8 bytes) + +#### Actions + +Get + +Reboot: Reboot the ONU + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|---------------------------------------------| +| 0 | Equipment alarm | Functional failure on an internal interface | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.1.14 ONU dynamic power management control + +This ME models the ONU's ability to enter power conservation modes in cooperation with the OLT in an ITU-T G.987 system. [ITU-T G.987.3] originally specified two alternative modes, doze and cyclic sleep. The subsequent revision of [ITU-T G.987.3] simplified the specification providing a single power conservation mode, watchful sleep. + +An ONU that supports power conservation modes automatically creates an instance of this ME. + +#### Relationships + +One instance of this ME is associated with the ONU ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Power reduction management capability:** This attribute declares the ONU's support for managed power conservation modes, as defined in [ITU-T G.987.3]. It is a bit map in which the bit value 0 indicates no support for the specified mode, while the bit value 1 indicates that the ONU does support the specified mode. (R) (mandatory) (1 byte) + +Codepoints are assigned as follows: + +| Value | Meaning | +|--------|--------------------------------------------| +| 0 | No support for power reduction | +| 1 | Doze mode supported | +| 2 | Cyclic sleep mode supported | +| 3 | Both doze and cyclic sleep modes supported | +| 4 | Watchful sleep mode supported | +| 5..255 | Reserved | + +**Power reduction management mode:** This attribute enables one or more of the ONU's managed power conservation modes. It is a bit map in which the bit value 0 disables the mode, while the value 1 enables the mode. Bit assignments are the same as those of the power reduction management capability attribute. The default value of each bit is 0. (R, W) (mandatory) (1 byte) + +**Itransinit:** This attribute is the ONU vendor's statement of the complete transceiver initialization time: the worst-case time required for the ONU to regain full functionality when leaving the asleep state in cyclic sleep mode or low-power state in watchful sleep mode (i.e., turning on both the receiver and the transmitter and acquiring synchronization to the downstream flow), measured in units of 125 µs frames. The value zero indicates that the sleeping ONU can respond to a bandwidth grant without delay. (R) (mandatory) (2 bytes) + +**Itxinit:** This attribute is the ONU vendor's statement of the transmitter initialization time: the time required for the ONU to regain full functionality when leaving the listen state (i.e., turning on the transmitter), measured in units of 125 µs frames. The value zero indicates that the dozing ONU can respond to a bandwidth grant without delay. If watchful sleep is enabled, the ONU ignores this attribute. (R) (mandatory) (2 bytes) + +**Maximum sleep interval:** The Isleep/Ilowpower attribute specifies the maximum time the ONU spends in its asleep, listen, or low-power states, as a count of 125 µs frames. Local or remote events may truncate the ONU's sojourn in these states. The default value of this attribute is 0. (R, W) (mandatory) (4 bytes) + +**Maximum receiver-off interval:** The Irxoff attribute specifies the maximum time the OLT can afford to wait from the moment it decides to wake up an ONU in the low-power state of the watchful sleep mode until the ONU is fully operational, specified as a count of 125 µs frames. (R, W) (mandatory) (4 bytes) + +**Minimum aware interval:** The Iaware attribute specifies the time the ONU spends in its aware state, as a count of 125 µs frames, before it re-enters asleep or listen states. Local or remote events may independently cause the ONU to enter an active state rather than returning to a sleep state. The default value of this attribute is 0. (R, W) (mandatory) (4 bytes) + +**Minimum active held interval:** The Ihold attribute specifies the minimum time during which the ONU remains in the active held state, as a count of 125 µs frames. Its initial value is zero. (R, W) (mandatory) (2 bytes) + +**Maximum sleep interval extension:** This attribute designates maximum sleep interval values for doze mode and cyclic sleep mode separately. When it supports this attribute, the ONU ignores the value of the maximum sleep interval attribute. + +| | | +|----------------------------------------------|---------| +| Maximum sleep interval for doze mode | 4 bytes | +| Maximum sleep interval for cyclic sleep mode | 4 bytes | + +Maximum sleep interval for doze mode specifies the maximum time the ONU spends in its listen state, as a count of 125 µs frames. Local or remote events may truncate the ONU's sojourn in these states. The default value is 0. + +Maximum sleep interval for cyclic sleep mode specifies the maximum time the ONU spends in its asleep state, as a count of 125 µs frames. Local or remote events may truncate the ONU's sojourn in these states. The default value is 0. If watchful sleep is enabled, the ONU ignores this attribute. + +(R, W) (optional) (8 bytes) + +**Ethernet passive optical network (EPON) capability extension:** This attribute declares EPON-specific capabilities for the dynamic power management control. + +Bits are assigned as follows. + +| Bit | Name | Setting | +|---------|------------------------------------------|----------------------------------| +| 1 (LSB) | AckCapable | 0: not supported
1: supported | +| 2 | Sleep indication capability | 0: not supported
1: supported | +| 3 | Early wake-up capability | 0: not supported
1: supported | +| 4 | Sleep mode selection at ONU's discretion | 0: not supported
1: supported | + +AckCapable has the value of supported if the ONU is capable of sending a SLEEP\_ACK message, which is defined in [IEEE P1904.1], in response to the SLEEP\_ALLOW message from the OLT. The ONU may select the appropriate power conservation method by itself if AckCapable is supported. + +Sleep indication capability represents ability to send a SLEEP\_INDICATION message, defined in [IEEE P1904.1], to initiate the power saving cycle from the ONU. + +Early wake-up capability shows whether the ONU has a function in which the ONU can awaken from the sleep mode based on local conditions such as off-hook condition on SIP ports and power down. + +ONU self-sleep mode selection indicates whether the ONU has a function to choose the appropriate power conservation method by itself if the SLEEP\_ALLOW message, defined in [ITU-T G.epon], designates the ONU to enter low-power sleep mode with a Tx or TRx SleepMode option. (Tx mode which is defined in [IEEE P1904.1] is equivalent to doze mode, and TRx mode which is also defined in [IEEE P1904.1] is equivalent to cyclic sleep mode.) + +(R) (optional) (1 byte) + +NOTE – The dynamic power management control in EPON is basically the same as the function in [ITU-T G.987.3]. That is EPON has two types of power-down modes which are equivalent to doze mode and cyclic sleep mode, where the former is defined as Tx mode and the latter is defined as TRx mode in [IEEE P1904.1]. + +However EPON has some differences from [ITU-T G.987.3] equivalent Tx mode or TRx mode: + +- EPON may be operated without the SLEEP\_ACK message (which is equivalent to Sleep\_Request message in [ITU-T G.987.3]) +- An EPON ONU may initiate the dynamic power management control sequence by an EPON-specific SLEEP\_INDICATION message. +- EPON may be operated without the early wake-up sequence, which is equivalent to the transition to a full power state by local wake-up indications (LWI) of ONU in [ITU-T G.987.3]. +- An EPON ONU may have no capability to choose Tx or TRx mode by itself. Therefore, the OLT can designate the ONU to enter a specific power-down mode in either explicit or implicit ways. + +To negotiate the power management mode, the ONU indicates its capabilities by this attribute and then the OLT configures the ONU with the EPON setup extension attribute. In case of the following capabilities and configurations, an EPON system performs the same power-saving function as [ITU-T G.987.3]. + +- Capabilities: +AckCapable = supported, +Sleep indication capability = N/A, +Early wake-up capability = supported, +ONU self-sleep mode selection = supported +- Configurations: +ackEnable configuration = enable, + +Sleep indication configuration = disable, +Early wake-up configuration = enable + +**EPON setup extension:** This attribute specifies EPON specific configurations for the dynamic power management control. + +The bits are assigned as follows. + +| Bit | Name | Setting | +|---------|--------------------------------|-------------------------| +| 1 (LSB) | ackEnable configuration | 0: disable
1: enable | +| 2 | Sleep indication configuration | 0: disable
1: enable | +| 3 | Early wake-up configuration | 0: disable
1: enable | +| 4..8 | Reserved | 0 | + +Each bit corresponds to bit 1-3 of the EPON capability extension and the OLT may enable each bit if the capability is supported or true. If the capability is not supported, the bit has no effect. + +If the OLT does not designate configurations by the EPON setup extension, the ONU uses the following default values unless they are not supported. + +ackEnable configuration = enable, +Sleep indication configuration = disable, +Early wake-up configuration = enable + +(R, W) (optional) (1 byte) + +Missing consecutive bursts threshold: The Clobi attribute specifies the maximum number of missing consecutive scheduled bursts from the ONU that the OLT is willing to tolerate without raising an alarm. The value of this attribute defaults to 4. +(R, W) (mandatory) (4 bytes) + +#### Actions + +Get, set + +#### Notifications + +None. + +### 9.1.15 ONU3-G + +This ME contains additional attributes and alarms associated with a PON ONU. The ONU automatically creates an instance of this ME. Its attributes are populated according to data within the ONU itself. + +Upon instantiation of this ME, the Total number of status snapshots $S$ , the Number of valid status snapshots $M$ , and Next status snapshot index $K$ are populated from the non-volatile memory. If the non-volatile memory values are not available (e.g., at the initialization of an off-the-shelf ONU), the Total number of status snapshots attribute is set to the maximum size of the status snapshot record table the ONU can maintain, which is a static capability parameter, while both the Number of valid status snapshots and the Next status snapshot index attributes are set to zero. + +The Status snapshot record table is implemented as a circular buffer containing up to $S$ records of size $N$ . The size and format of the snapshot record are vendor-specific. Each time the ONU takes and stores a status snapshot, it increments the Number of valid status snapshots $M$ , saturating at $S$ , and increments Next status snapshot index $K$ in modulo $S$ : + +$$K := (K + 1) \bmod S.$$ + +By writing into the Snap action attribute, the OLT instructs the ONU to immediately take a status snapshot and to store it in the Status snapshot table. By writing into Reset action attribute, the OLT instructs the ONU to erase the Status snapshot record table. The OLT uses the AVC indication of the Next status snapshot index and Number of valid status snapshots attributes to confirm that its instructions have been executed by the ONU. If the OLT has issued no Snap action instructions, a change in the value of Next status snapshot index attributes between two consecutive reads indicates that a condition has arisen that has caused the ONU to record a status snapshot. + +Two table attributes, the Status snapshot record table, and the Most recent status snapshot, provide the OLT access to the status snapshot records. The former allows the entire Status snapshot record table to be retrieved, the latter provides quick access to the latest snapshot record. + +By performing the Get operation on the Most recent status snapshot, the OLT can obtain the vendor-specific size of an individual snapshot record. The OLT is expected to pass the status snapshot records transparently, without parsing or interpreting them. + +#### *Relationships* + +This ME is associated with the ONU-G ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Flash memory performance value:** A number in the range from 0 to 100 that characterizes the condition of the flash memory, with 0 representing factory fresh device, 100 representing end of life. This attribute is vendor-specific and should be calculated at the discretion of the vendor. (R) (optional) (1 byte) + +**Latest restart reason:** The following code points are defined: + +0x00 – Unspecified other; + +0x01 – OLT initiated software restart remotely by OMCI/PLOAM; + +0x02 – User initiated hardware restart; + +0x03 – Self-monitor timer expiration; + +0x04 – Hardware error (bus time-out, misaligned memory access, etc.); + +0x05 – Hardware auto-restart (on-board voltage monitor auto-restart, etc.); + +0x06 – Over temperature; + +0x07 – Software out of memory; + +0x08 – Software auto-restart (unresolvable references, critical internal inconsistency); + +0x09 – User initiated software restart locally by CLI/WEB; + +0x0A..0xDC – Reserved for future use; + +0xDD..0xFF – Reserved for the ONU vendor use. + +Other codepoints reserved. (R) (mandatory) (1 byte) + +**Total number of status snapshots:** The maximum size $S$ of the status snapshot record table. (R) (mandatory) (2 bytes) + +**Number of valid status snapshots:** The number $M$ of valid status snapshot records. (R) (mandatory) (2 bytes) + +**Next status snapshot index:** This attribute identifies the index (ranging from 0 to $S - 1$ ) of the next snapshot record to be taken in the snapshot record table. (R,) (mandatory) (2 bytes) + +**Status snapshot record table:** The table of $M$ status snapshot records. The size $N$ and format of the snapshot record is vendor dependent. (R) (mandatory) ( $M \times N$ bytes) + +**Snap action:** Once the OLT writes this attribute, the ONU takes and records an urgent snapshot without shutting down the transceiver. (W) (mandatory) (1 byte) + +**Most recent status snapshot:** This attribute provides access to the most recently taken status snapshot record. (R) (mandatory) ( $N$ bytes) + +**Reset action:** Once the OLT writes this attribute, the ONU sets the Number of valid status snapshots and Next status snapshot index attributes to zero. (W) (mandatory) (1 byte) + +**Enhanced mode:** The Boolean value true specifies the Enhanced received frame classification and processing table is supported by the Extended VLAN tagging operation configuration ME. The value false indicates the Enhanced received frame classification and processing table is not supported. (R) (optional) (1 byte) + +Actions + +Get, get-next, set + +*Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------| +| 1 | Flash mem perf | Flash memory performance value change | +| 2 | N/A | | +| 3 | N/A | | +| 4 | No of valid snapshots | A new snapshot has been recorded | +| 5 | N/A | | +| 6 | N/A | | +| 7 | N/A | | +| 8..16 | Reserved | | + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|---------------------------------|----------------------------------------------------------------------------------------------------------------| +| 0 | Flash memory performance yellow | | +| 1 | Flash memory performance red | | +| 2 | Loss of redundant power supply | In an ONU with redundant power supplies, an indication of the loss of one of the two redundant power supplies. | +| 3 | Loss of redundant power feed | In an ONU with dual -48DC power feeds, an indication of the loss of one of the two power feeds. | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|--------------|-----------------------------------------------------------------------------------------------| +| 4 | Ground Fault | Ground fault; ONU has detected a loss of grounding or a degradation in the ground connection. | + +### 9.1.16 ONU manufacturing data + +This ME contains additional manufacturing attributes associated with a PON ONU. The manufacturing data is expected to match the content of an ONU label. The ONU automatically creates an instance of this ME. Its attributes are populated according to data within the ONU itself. + +#### *Relationships* + +This ME is paired with the ONU-G entity. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Manufacturer name:** This attribute contains the manufacturer name of this physical ONU. The preferred value is the manufacturer name string printed on the ONU itself (if present). (R) (optional) (25 bytes) + +**Serial number part 1, serial number part 2:** These two attributes may be regarded as an ASCII string of up to 32 bytes whose length is a left justified manufacturer's serial number for this physical ONU. The preferred value is the manufacturer serial number string printed on the ONU itself (if present). (R) (optional) (25 bytes\*2 attributes) + +**Model name:** This attribute contains the vendor specific model name identifier string. The preferred value is the customer-visible part number which may be printed on the component itself. (R) (optional) (25 bytes) + +**Manufacturing date:** This attribute contains the date of manufacturer of this physical ONU. The preferred value is the date of the manufacturer printed on the ONU itself (if present). (R) (optional) (25 bytes) + +**Hardware-revision:** This attribute contains the hardware revision of this physical ONU. The preferred value is the hardware revision printed on the ONU itself (if present). (R) (optional) (25 bytes) + +**Firmware-revision:** This attribute contains the vendor specific firmware revision of this physical ONU. (R) (optional) (25 bytes) + +#### *Actions* + +Get + +#### *Notifications* + +None + +### 9.1.17 ONU time configuration + +This ME provides characterization and manipulation of OLT timestamp information. An ONU that uses OLT-based time synchronization methods automatically creates an instance of this ME. There is no intention that this ME be used to establish a precise time of day reference. + +#### Relationships + +The single instance of this ME is associated with the ONU ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Current local ONU time:** If the ONU has a real-time clock, it returns the local ONU time. This attribute returns the current ONU time. The local ONU time and synchronize time time-format is the same. (R) (mandatory) (7 bytes) + +| Byte | Description | +|------|-------------------------------| +| 1-2 | Year, e.g., 2009 | +| 3 | Month, range 1..12 | +| 4 | Day of month, range 1..31 | +| 5 | Hour of day, range 0..23 | +| 6 | Minute of hour, range 0..59 | +| 7 | Second of minute, range 0..59 | + +**Time qualification block:** This attribute describes the time-qualification to be applied to the ONU RTC local time. The following fields are supported: + +| Bits | | | | | | | | | | | | | | | | +|------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|----|----------------------------------|------------------------------------------------|----|---|---|---|---|---|---|---|---|---| +| 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| Time qualification | Timezone offset | Reserved | | RFC 3339 time offset sign | RFC 3339 minutes offset (from UTC time) | | | | | | | | | | | +| where | | | | | | | | | | | | | | | | +| Time qualification (1-bit) | This attribution qualifies the OLT time. Valid values are:
0 The OLT is locally timed
1 The OLT timestamps are UTC timestamped | | | | | | | | | | | | | | | +| Timezone information (1-bit) | This attribute governs the time offset behaviour of the ONU RTC:
0 No timezone offset information
1 Timezone offset provided in the RFC 3339 time offset | | | | | | | | | | | | | | | + +| | | +|---------------------------------------------------|-------------------------------------------------------------------------------------------------------------| +| RFC 3339 Time offset sign (from UTC time) (1-bit) | RFC 3339 Timesone offset sign. A value of 0 indicates a positive offset and a 1 indicates a negative offset | +| RFC 3339 minutes offset (from UTC time) (11-bits) | Describes the RFC 3339 minutes offset | + +(R, W) (mandatory) (2 bytes) + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.1.18 ONU operational performance monitoring history data** + +This managed entity collects performance monitoring data associated with the ONU instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with the ONU-G managed entity. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set by create) (mandatory) (2 bytes) + +**Temperature sensor value:** A table of one-byte temperature sensor values, each being represented by a 2s complement integer that specifies the average temperature of the ONU temperature sensor(s) during the measurement interval. Valid values are –40 to +127 °C in 1 °C increments. The special values: 0x80 indicates that the temperature sensor is not available; 0x81, that the sensor has malfunctioned. (R) (mandatory) (N byte) + +NOTE – Sampling rates of temperature are outside the scope of this specification). + +**Temperature sensor description:** A table of 25-byte long temperature sensor descriptions, each represented by a character string that includes the physical location on the ONU or the component being measured. Strings shorter than 25 bytes are padded with null characters. (R) (mandatory) (25N bytes). + +BEST PRACTICE NOTE: The order of the temperature sensor description and temperature sensor values should match and be maintained. Care should be taken that the temperature sensor names do not change across measurement intervals nor ONU reboots. A temperature sensor name may change as a result of a ONU software upgrade (when a new sensor is reported upon). + +**CPU percent utilization:** The maximum system CPU utilization (high water mark) during the measurement interval. For multi-processor systems, the CPU utilization values are global maximum across all processors (e.g., if one core is 50% CPU utilization, 3 other cores are 10% CPU utilization, the global CPU utilization is 50%). This attribute is an integer ranging from 0 to 100. A value of 100 indicates that at least one CPU was fully utilized, and a value of 0 indicates all + +the CPUs were idle during the measurement interval. The value of 0xFF indicates that no reliable measurement is available. (R) (mandatory) (1 byte) + +**RAM size available:** The minimum RAM size (in Megabytes) available during the measurement interval. This attribute is an integer from 1 to $2^{32} - 2$ . The value of 0xFFFFFFFF indicates that RAM size report is not reliable. (R) (mandatory) (4 bytes) + +**RAM utilization:** The maximum RAM size (in Megabytes) utilized during the measurement interval. This attribute is an integer from 0 to $2^{32} - 2$ . The value of 0xFFFFFFFF indicates that no reliable measurement is available. (R) (mandatory) (4 bytes) + +**FLASH size available:** The minimum FLASH size (in Megabytes) available during the measurement interval. This attribute is an integer from 1 to $2^{32} - 2$ . The value of 0xFFFFFFFF indicates that FLASH size report is not reliable. (R) (mandatory) (4 bytes) + +**FLASH utilization:** The maximum FLASH size (in Megabytes) utilized during the measurement interval. This attribute is an integer from 0 to $2^{32} - 2$ . The value of 0xFFFFFFFF indicates that no reliable measurement is available. (R) (mandatory) (4 bytes) + +**Software errors:** A count of the number of software errors detected. A software error is an error, flaw, failure or fault in a computer program that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. Examples include internal logical inconsistencies, division by zero, referencing to non-existent memory, writing to read-only-memory and "exceptions" in certain programming languages (such as C++ and Java) (R) (mandatory) (4 bytes) + +**Errors in operations:** A count of the number of detected errors in operations, not due to a software error. Examples include reading MEs that do not exist, provisioning services on entities that do not exist, deleting entities that do not exist. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, get next, set + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | CPU utilization | 1 | +| 1 | RAM utilization | 2 | +| 2 | FLASH utilization | 3 | +| 3 | Software errors | 4 | +| 4 | Errors in operations | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.1.19 ONU4-G + +The ONU4-G describes the ONU's ANI line rate buffering capabilities, in both upstream and downstream direction. It defines the sustained MAC client interface rate and the rate adaptation buffer (RAB) size that the ONU supports as shown in Figure 9.1.19-1. If the OLT does not take these factors into account in its downstream shaping or upstream BWmap generation, then that may result in packet drop in the downstream direction and waste of bandwidth in the upstream direction. + +![Figure 9.1.19-1 – ONU rate adaptation buffer model. The diagram shows the internal architecture of an ONU. On the left, the ANI (PON port) connects to a PON interface containing a PMD and a TC. The TC connects to a G (50 Gb/s) interface. The G interface connects to a Packet processing (QoS) block, which contains two RAB (Rate Adaptation Buffer) units, a Q-ing unit, and a Packet processing unit. The Packet processing unit connects to a UNI (Client Ethernet port), which in turn connects to a Client application. The diagram is labeled G.988(17)-Amd.5(22)_F9.1.19-1.](27d6042f4bce01ea5789efbd9e8d1f50_img.jpg) + +Figure 9.1.19-1 – ONU rate adaptation buffer model. The diagram shows the internal architecture of an ONU. On the left, the ANI (PON port) connects to a PON interface containing a PMD and a TC. The TC connects to a G (50 Gb/s) interface. The G interface connects to a Packet processing (QoS) block, which contains two RAB (Rate Adaptation Buffer) units, a Q-ing unit, and a Packet processing unit. The Packet processing unit connects to a UNI (Client Ethernet port), which in turn connects to a Client application. The diagram is labeled G.988(17)-Amd.5(22)\_F9.1.19-1. + +Figure 9.1.19-1 – ONU rate adaptation buffer model + +This ME is autonomously created by the ONU. + +#### Relationships + +This ME is associated with an ONU-G ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Sustained downstream MAC client rate:** This attribute specifies the sustained downstream MAC client rate this ONU is capable to receive, in 10 Mbit/s units. (R) (mandatory) (2 bytes) + +**Downstream RAB size:** Indicates the size of the downstream rate adaptation buffer, expressed in 1024-byte blocks. A minimum size of 128 blocks is recommended. (R) (mandatory) (2 bytes) + +**Sustained upstream MAC client rate:** This attribute specifies the sustained upstream MAC client rate this ONU is capable to transmit, in 10 Mbit/s units. (R) (mandatory) (2 bytes) + +**Upstream RAB size:** Indicates the size of the upstream rate adaptation buffer, expressed in 1024-byte blocks. A minimum size of 128 blocks is recommended. (R) (mandatory) (2 bytes) + +#### Actions + +Get + +#### Notifications + +None + +## 9.2 ANI management, traffic management + +### 9.2.1 ANI-G + +This ME organizes data associated with each access network interface supported by a G-PON ONU. The ONU automatically creates one instance of this ME for each PON physical port. + +#### Relationships + +An instance of this ME is associated with each instance of a physical PON interface. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value indicates the physical position of the PON interface. The first byte is the slot ID, defined in clause 9.1.5. The second byte is the port ID. (R) (mandatory) (2 bytes) + +**SR indication:** This Boolean attribute indicates the ONU's capability to report queue status for DBA. The value true means that status reporting is available for all T-CONTs that are associated with the ANI. (R) (mandatory) (1 byte) + +**Total T-CONT number:** This attribute indicates the total number of T-CONTs that can be supported on this ANI. (R) (mandatory) (2 bytes) + +**GEM block length:** This attribute specifies the queue occupancy reporting granularity for DBA, expressed in bytes. This attribute is meaningful only in ITU-T G.984.x systems. (R, W) (mandatory) (2 bytes) + +In ITU-T G.984 systems, the value set by the OLT is used by all T-CONTs on this ANI. Upon ME instantiation, the ONU sets this attribute to 48. See [ITU-T G.984.3] for further details. + +In all other ITU-T PON systems, the unit for queue occupancy reporting is fixed in at 4 bytes by the respective TC layer specification. + +**Piggyback DBA reporting:** This attribute indicates the ONU's piggyback DBA reporting format capabilities. [ITU-T G.984.3] defines two possible piggyback reporting modes. For reporting mode 0, the single field is the entire report. For reporting mode 1, the DBA report is two fields long. Mode 0 is mandatory for ITU-T G.984 ONUs that support piggyback DBA reporting; mode 1 is optional. Subsequent PON specifications allows only one mode, which should be reported in this attribute as code point 0. + +The following coding indicates the ONU's piggyback DBA reporting mode capabilities: + +- 0 Mode 0 only +- 1 Modes 0 and 1 +- 2 Deprecated +- 3 Deprecated +- 4 Piggyback DBA reporting not supported + +(R) (mandatory) (1 byte) + +**Deprecated:** This attribute should be set to 0 by the ONU and ignored by the OLT. (R) (mandatory) (1 byte) + +**Signal fail (SF) threshold:** This attribute specifies the downstream bit error rate (BER) threshold to detect the SF alarm. When this value is $y$ , the BER threshold is $10^{-y}$ . Valid values are 3..8. Upon ME instantiation, the ONU sets this attribute to 5. (R, W) (mandatory) (1 byte) + +**Signal degrade (SD) threshold:** This attribute specifies the downstream BER threshold to detect the SD alarm. When this value is $x$ , the BER threshold for SD is $10^{-x}$ . Valid values are 4..10. The SD threshold must be lower than the SF threshold; i.e., $x > y$ . Upon ME instantiation, the ONU sets this attribute to 9. (R, W) (mandatory) (1 byte) + +- ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) +- ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) +- Optical signal level:** This attribute reports the current measurement of the total downstream optical signal level. Its value is a 2s complement integer referred to 1 mW (i.e., 1 dBm), with 0.002 dB granularity. (R) (optional) (2 bytes) +- Lower optical threshold:** This attribute specifies the optical level the ONU uses to declare the downstream low received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the ONU's internal policy. (R, W) (optional) (1 byte) +- Upper optical threshold:** This attribute specifies the optical level the ONU uses to declare the downstream high received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the ONU's internal policy. (R, W) (optional) (1 byte) +- ONU response time:** This attribute indicates the ONU's actual response time. This attribute is in the range 34..36 µs. Although this attribute is expressed in nanoseconds, its accuracy is likely to be more coarse. Furthermore, the value may change from one activation cycle to the next. Valid values are: +0 (Null, function not supported) +34000 to 36000 (response time in nanoseconds) +All other values reserved +(R) (optional) (2 bytes) +- Transmit optical level:** This attribute reports the current measurement of mean optical launch power. Its value is a 2s complement integer referred to 1 mW (i.e., 1 dBm), with 0.002 dB granularity. (R) (optional) (2 bytes) +- Lower transmit power threshold:** This attribute specifies the minimum mean optical launch power that the ONU uses to declare the low transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value –63.5 (0x81) selects the ONU's internal policy. (R, W) (optional) (1 byte) +- Upper transmit power threshold:** This attribute specifies the maximum mean optical launch power that the ONU uses to declare the high transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value –63.5 (0x81) selects the ONU's internal policy. (R, W) (optional) (1 byte) + +#### Actions + +Get, set + +**Test:** Test the ANI-G. The test action can be used to perform optical line supervision tests; refer to Annex A. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------------| +| 1..7 | N/A | | +| 8 | ARC | Alarm-reporting control cancellation | +| 9..16 | N/A | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Low received optical power | Received downstream optical power below threshold. | +| 1 | High received optical power | Received downstream optical power above threshold. | +| 2 | SF | Bit error-based signal fail. Industry practice normally expects the BER to improve by at least an order of magnitude before clearing the alarm. | +| 3 | SD | Bit error-based signal degrade. Industry practice normally expects the BER to improve by at least an order of magnitude before clearing the alarm. | +| 4 | Low transmit optical power | Transmit optical power below lower threshold | +| 5 | High transmit optical power | Transmit optical power above upper threshold | +| 6 | Laser bias current | Laser bias current above threshold determined by vendor; laser end of life pending | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +**Test result:** The ONU may report a test result autonomously if it performs self-test functions autonomously. + +### 9.2.2 T-CONT + +An instance of the traffic container ME T-CONT represents a logical connection group associated with a G-PON PLOAM layer alloc-ID. A T-CONT can accommodate GEM packets in priority queues or traffic schedulers that exist in the GEM layer. + +The ONU autonomously creates instances of this ME. The OLT can discover the number of T-CONT instances via the ANI-G ME. When the ONU's MIB is reset or created for the first time, all supported T-CONTs are created. The OLT provisions alloc-IDs to the ONU via the PLOAM channel. Via the OMCI, the OLT must then set the alloc-ID attributes in the T-CONTs that it wants to activate for user traffic, to create the appropriate association with the allocation ID in the PLOAM channel. There should be a one-to-one relationship between allocation IDs and T-CONT MEs; the connection of multiple T-CONTs to a single allocation ID is undefined. + +The allocation ID that matches the ONU-ID itself is defined to be the default alloc-ID. This alloc-ID is used to carry the OMCC. The default alloc-ID can also be used to carry user traffic, and hence can be assigned to one of the T-CONT MEs. However, this OMCI relationship only pertains to user traffic, and the OMCC relationship is unaffected. It can also be true that the OMCC is not contained in any T-CONT ME construct; rather, that the OMCC remains outside of the OMCI, and that the OMCI is not used to manage the OMCC in any way. Multiplexing of the OMCC and user data in G-PON systems is discussed in clause B.2.4. + +#### Relationships + +One or more instances of this ME are associated with an instance of a circuit pack that supports a PON interface function, or with the ONU-G itself. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical capability that realizes the T-CONT. It may be represented as 0xSSBB, where SS indicates the slot ID that contains this T-CONT (0 for the ONU as a whole), and BB is the T-CONT ID, numbered by the ONU itself. T-CONTs are numbered in ascending order, with the range 0..255 in each slot. (R) (mandatory) (2 bytes) + +**Alloc-ID:** This attribute links the T-CONT with the alloc-ID assigned by the OLT in the assign\_alloc-ID PLOAM message. The respective TC layer specification should be referenced for the legal values for that system. Prior to the setting of this attribute by the OLT, this attribute has an unambiguously unusable initial value, namely the value 0x00FF or 0xFFFF for ITU-T G.984 systems, and the value 0xFFFF for all other ITU-T GTC based PON systems. (R, W) (mandatory) (2 bytes) + +**Deprecated:** The ONU should set this attribute to the value 1, and the OLT should ignore it. (R) (mandatory) (1 byte) + +**Policy:** This attribute indicates the T-CONT's traffic scheduling policy. Valid values: +0 Null +1 Strict priority +2 WRR – Weighted round robin +(R, W) (mandatory) (1 byte) + +NOTE – This attribute is read-only, unless otherwise specified by the QoS configuration flexibility attribute of the ONU2-G ME. If flexible configuration is not supported, the ONU should reject an attempt to set it with a parameter error result-reason code. + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.2.3 GEM port network CTP** + +This ME represents the termination of a GEM port on an ONU. This ME aggregates connectivity functionality from the network view and alarms from the network element view as well as artefacts from trails. + +Instances of the GEM port network CTP ME are created and deleted by the OLT. An instance of GEM port network CTP can be deleted only when no GEM IW TP or GEM port network CTP PM history data are associated with it. It is the responsibility of the OLT to make sure that the ONU configuration meets this condition. + +In ITU-T G.984 systems, when a GEM port network CTP is created, its encryption state is by default not encrypted. If the OLT wishes to configure the GEM port to use encryption, it must send the appropriate PLOAM message. This applies equally to new CTPs and to CTPs that are re-created after an MIB reset. + +In ITU-T G.987 systems, GEM ports are dynamically encrypted. If it is intended to encrypt the GEM port, the OLT must configure a key ring to be used, and the key must be known to the ONU at run time. + +#### Relationships + +An instance of the GEM port network CTP ME may be associated with an instance of the T-CONT and GEM IW TP MEs. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Port-ID:** This attribute is the port-ID of the GEM port associated with this CTP. (RWSC) (mandatory) (2 bytes) + +NOTE 1 – While nothing forbids the existence of several GEM port network CTPs with the same port-ID value, downstream traffic is modelled as being delivered to all such GEM port network CTPs. Be aware of potential difficulties associated with defining downstream flows and aggregating PM statistics. + +**T-CONT pointer:** This attribute points to a T-CONT instance. (R, W, set-by-create) (mandatory) (2 bytes) + +**Direction:** This attribute specifies whether the GEM port is used for UNI-to-ANI (1), ANI-to-UNI (2), or bidirectional (3) connection. (R, W, set-by-create) (mandatory) (1 byte) + +**Traffic management pointer for upstream:** If the traffic management option attribute in the ONU-G ME is 0 (priority controlled) or 2 (priority and rate controlled), this pointer specifies the priority queue ME serving this GEM port network CTP. If the traffic management option attribute is 1 (rate controlled), this attribute redundantly points to the T-CONT serving this GEM port network CTP. (R, W, set-by-create) (mandatory) (2 bytes) + +**Traffic descriptor profile pointer for upstream:** This attribute points to the instance of the traffic descriptor ME that contains the upstream traffic parameters for this GEM port network CTP. This attribute is used when the traffic management option attribute in the ONU-G ME is 1 (rate controlled), specifying the PIR/PBS to which the upstream traffic is shaped. This attribute is also used when the traffic management option attribute in the ONU-G ME is 2 (priority and rate controlled), specifying the CIR/CBS/PIR/PBS to which the upstream traffic is policed. (R, W, set-by-create) (optional) (2 bytes) + +See also Appendix II. + +**UNI counter:** This attribute reports the number of instances of UNI-G ME associated with this GEM port network CTP. (R) (optional) (1 byte) + +**Priority queue pointer for downstream:** This attribute points to the instance of the priority queue used for this GEM port network CTP in the downstream direction. It is the responsibility of the OLT to provision the downstream pointer in a way that is consistent with the bridge and mapper connectivity. If the pointer is null, downstream queueing is determined by other mechanisms in the ONU. (R, W, set-by-create) (mandatory) (2 bytes) + +NOTE 2 – If the GEM port network CTP is associated with more than one UNI (downstream multicast), the downstream priority queue pointer defines a pattern (e.g., queue number 3 for a given UNI) to be replicated (i.e., to queue number 3) at the other affected UNIs. + +**Encryption state:** This attribute indicates the current state of the GEM port network CTP's encryption. Legal values are defined to be the same as those of the security mode attribute of the ONU2-G, with the exception that attribute value 0 indicates an unencrypted GEM port. (R) (optional) (1 byte) + +**Traffic descriptor profile pointer for downstream:** This attribute points to the instance of the traffic descriptor ME that contains the downstream traffic parameters for this GEM port network CTP. This attribute is used when the traffic management option attribute in the ONU-G ME is 1 (rate controlled), specifying the PIR/PBS to which the downstream traffic is shaped. This attribute is also used when the traffic management option attribute in the ONU-G ME is 2 (priority and rate controlled), specifying the CIR/CBS/PIR/PBS to which the downstream traffic is policed. (R, W, set-by-create) (optional) (2 bytes) + +See also Appendix II. + +**Encryption key ring:** This attribute is defined in ITU-T G.987 systems only. It specifies whether the associated GEM port is encrypted, and if so, which key ring it uses. (R, W, set-by-create) (optional) (1 byte) + +- 0 (default) No encryption. The downstream key index is ignored, and upstream traffic is transmitted with key index 0. +- 1 Unicast payload encryption in both directions. Keys are generated by the ONU and transmitted to the OLT via the PLOAM channel. +- 2 Broadcast (multicast) encryption. Keys are generated by the OLT and distributed via the OMCI. +- 3 Unicast encryption, downstream only. Keys are generated by the ONU and transmitted to the OLT via the PLOAM channel. + +Other values are reserved. + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +#### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|-------------------------------|----------------------------------------------------------------------------------------------------------------------------| +| 0..4 | Reserved | | +| 5 | End-to-end loss of continuity | Loss of continuity can be detected when the GEM port network CTP supports a GEM interworking termination point (optional). | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.2.4 GEM interworking termination point** + +An instance of this ME represents a point in the ONU where the IW of a bearer service (usually Ethernet) to the GEM layer takes place. At this point, GEM packets are generated from the bearer bit stream (e.g., Ethernet) or the bearer bit stream is reconstructed from GEM packets. + +Instances of this ME are created and deleted by the OLT. + +#### Relationships + +One instance of this ME exists for each transformation of a data stream into GEM frames and *vice versa*. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**GEM port network CTP connectivity pointer:** This attribute points to an instance of the GEM port network CTP. (R, W, set-by-create) (mandatory) (2 bytes) + +**Interworking option:** This attribute identifies the type of non-GEM function that is being interworked. The options are as follows. + +- 0 Circuit-emulated TDM +- 1 MAC bridged LAN +- 2 Reserved +- 3 Reserved +- 4 Video return path +- 5 IEEE 802.1p mapper +- 6 Downstream broadcast +- 7 MPLS PW TDM service + +(R, W, set-by-create) (mandatory) (1 byte) + +**Service profile pointer:** This attribute points to an instance of a service profile: + +| | | +|------------------------------------|------------------| +| CES service profile | if IW option = 0 | +| MAC bridge service profile | if IW option = 1 | +| Video return path service profile | if IW option = 4 | +| IEEE 802.1p mapper service profile | if IW option = 5 | +| Null pointer | if IW option = 6 | +| CES service profile | if IW option = 7 | + +(R, W, set-by-create) (mandatory) (2 bytes) + +NOTE – The video return path (VRP) service profile is defined in [ITU-T G.984.4]. + +**Interworking termination point pointer:** This attribute is used for the CES and IEEE 802.1p mapper service without a MAC bridge. Depending on the service provided, it points to the associated instance of the following MEs: + +- PPTP CES UNI +- Logical $N \times 64$ kbit/s sub-port CTP +- PPTP Ethernet UNI + +In all other GEM services, the relationship between the related service TP and this GEM IW TP is derived from other ME relations; this attribute is set to a null pointer and not used. (R, W, set-by-create) (mandatory) (2 bytes) + +**PPTP counter:** This value reports the number of PPTP ME instances associated with this GEM IW TP. (R) (optional) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**GAL profile pointer:** This attribute points to an instance of the GAL profile. The relationship between the IW option and the related GAL profile is as follows. + +| Interworking option | GAL profile type | +|---------------------|---------------------------------------------| +| 0 | Null pointer | +| 1 | GAL Ethernet profile | +| 3 | GAL Ethernet profile for data service | +| 4 | GAL Ethernet profile for video return path | +| 5 | GAL Ethernet profile for IEEE 802.1p mapper | +| 6 | Null pointer | +| 7 | Null pointer | + +(R, W, set-by-create) (mandatory) (2 bytes) + +**GAL loopback configuration:** This attribute sets the loopback configuration when using GEM mode: + +- 0 No loopback +- 1 Loopback of downstream traffic after GAL + +The default value of this attribute is 0. When the IW option is 6 (downstream broadcast), this attribute is not used. (R, W) (mandatory) (1 byte) + +#### Actions + +Create, delete, get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..5 | N/A | | +| 6 | Op state | Operational state change | +| 7..8 | N/A | | +| 9..16 | Reserved | | + +#### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------| +| 0 | Deprecated | | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.2.5 Multicast GEM interworking termination point + +An instance of this ME represents a point in a G-PON ONU where a multicast service interworks with the GEM layer. At this point, a multicast bit stream is reconstructed from GEM packets. + +Instances of this ME are created and deleted by the OLT. + +#### Multicast interworking GEM modes of operation + +The default multicast operation of the PON is where all the multicast content streams are carried in one PON layer connection (GEM port). This connection is then specified in the first entry of the IPv4 or IPv6 multicast address table, as the case may be. This single entry also specifies an all-inclusive IP multicast destination address (DA) range (e.g., 224.0.0.0 to 239.255.255.255 in the case of IPv4). The ONU then filters the traffic based on either Ethernet MAC addresses or IP addresses. + +The associated GEM port network CTP ME specifies the GEM port-ID that supports all multicast connections. + +In the default multicast operation, all multicast content streams are placed in one PON layer connection (GEM port). The OLT sets up a completely conventional model, a pointer from the multicast GEM IW termination to a GEM port network CTP. The OLT configures the GEM port-ID of the GEM port network CTP into the appropriate multicast address table attribute(s), along with the other table fields that specify the range of IP multicast DAs. The ONU accepts the entire multicast stream through the designated GEM port, then filters the traffic based on either the Ethernet MAC address or IP DA. + +An optional multicast configuration supports separate multicast streams carried over separate PON layer connections, i.e., on separate GEM ports. This permits the ONU to filter multicast streams at the GEM level, which is efficient in hardware, while ignoring other multicast streams that may be of interest to other ONUs on the PON. + +After configuring the explicit model for the first multicast GEM port, the OLT supports multiple multicast GEM ports by then configuring additional entries into the multicast address table(s), entries with different GEM port-IDs. The OMCI model is defined such that these ports are implicitly grouped together and served by the single explicit GEM port network CTP. No additional GEM network CTPs need be created or linked for the additional GEM ports. + +Several multicast GEM IW TPs can exist, each linked to separate bridge ports or mappers to serve different communities of interest in a complex ONU. + +#### Discovery of multicast support + +The OLT uses the multicast GEM IW TP entity as the means to discover the ONU's multicast capability. This entity is mandatory if multicast is supported by the ONU. If the OLT attempts to create this entity on an ONU that does not support multicast, the create command fails. The create or set command also fails if the OLT attempts to exploit optional features that the ONU does not support, e.g., in attempting to write a multicast address table with more than a single entry or to create multiple multicast GEM IW TPs. + +This ME is defined by a similarity to the unicast GEM IW TP, and a number of its attributes are not meaningful in a multicast context. These attributes are set to 0 and not used, as indicated in the following. + +#### *Relationships* + +An instance of this ME exists for each occurrence of transformation of GEM packets into a multicast data stream. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0xFFFF is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**GEM port network CTP connectivity pointer:** This attribute points to an instance of the GEM port network CTP that is associated with this multicast GEM IW TP. (R, W, set-by-create) (mandatory) (2 bytes) + +**Interworking option:** This attribute identifies the type of non-GEM function that is being interworked. The option can be as follows. + +- 0 This value is a "no-op" or "don't care". It should be used when the multicast GEM IW TP is associated with several functions of different types. It can optionally be used in all cases, since the necessary information is available elsewhere. The previous code points are retained for backward compatibility: + +- 1 MAC bridged LAN +- 3 Reserved +- 5 IEEE 802.1p mapper + +(R, W, set-by-create) (mandatory) (1 byte) + +**Service profile pointer:** This attribute is set to 0 and not used. For backward compatibility, it may also be set to point to a MAC bridge service profile or IEEE 802.1p mapper service profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Not used 1:** This attribute is set to 0 and not used. (R, W, set-by-create) (mandatory) (2 bytes) + +**PPTP counter:** This attribute represents the number of instances of PPTP MEs associated with this instance of the multicast GEM IW TP. This attribute conveys no information that is not available elsewhere; it may be set to 0xFF and not used. (R) (optional) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**GAL profile pointer:** This attribute is set to 0 and not used. For backward compatibility, it may also be set to point to a GAL Ethernet profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Not used 2:** This attribute is set to 0 and not used. (R, W, set-by-create) (mandatory) (1 byte) + +**IPv4 multicast address table:** This attribute maps IP multicast addresses to PON layer addresses. Each entry contains the following. + +| | | +|-----------------------------|---------| +| GEM port-ID | 2 bytes | +| Secondary key | 2 bytes | +| IP multicast DA range start | 4 bytes | +| IP multicast DA range stop | 4 bytes | + +The first four bytes of each entry are treated as a key into the list. The secondary key allows the table to contain more than a single range for a given GEM port. + +A set action to a particular value overwrites any existing entry with the same first four bytes. If the last eight bytes of a set command are all zero, that entry is deleted from the list, as the IP address 0.0.0.0 is not valid. + +(R, W) (mandatory) ( $12N$ bytes, where $N$ is the number of entries in the list.) + +**IPv6 multicast address table:** This attribute maps IPv6 multicast DAs to PON layer addresses. Each entry contains: + +| | | +|---------------------------------------------------------|----------| +| GEM port-ID | 2 bytes | +| Secondary key | 2 bytes | +| Least significant bytes,
IP multicast DA range start | 4 bytes | +| Least significant bytes,
IP multicast DA range stop | 4 bytes | +| Most significant bytes, IP DA | 12 bytes | + +The first four bytes of each entry are treated as a key into the list. The secondary key allows the table to contain more than a single range for a given GEM port. + +A set action to a particular value overwrites any existing entry with the same first four bytes. If the last 20 bytes of a set command are all zero, that entry is deleted from the list. + +(R, W) (optional) ( $24N$ bytes, where $N$ is the number of entries in the list.) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..5 | N/A | | +| 6 | Op state | Operational state change | +| 7..9 | N/A | | +| 10..16 | Reserved | | + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------| +| 0 | Deprecated | | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.2.6 This clause is intentionally left blank** + +### **9.2.7 GAL Ethernet profile** + +This ME organizes data that describe the gigabit-capable passive optical network transmission convergence layer (GTC) adaptation layer processing functions of the ONU for Ethernet services. It is used with the GEM IW TP ME. + +Instances of this ME are created and deleted on request of the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the GEM IW TP ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Maximum GEM payload size:** This attribute defines the maximum payload size generated in the associated GEM IW TP ME. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.2.8 GAL Ethernet performance monitoring history data + +This ME collects PM data associated with a GEM IW TP when the GEM layer supports an Ethernet service. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the GEM IW TP ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the GEM IW TP. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Discarded downstream frames:** This attribute counts the number of downstream GEM frames discarded for any reason [erroneous frame check sequence (FCS), too long length, buffer overflow, etc.]. (R) (mandatory) (4 bytes) + +**Discarded upstream frames:** This attribute counts the number of upstream frames discarded prior to GEM encapsulation (due to congestion). (R) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-----------------------------|--------------------------------------| +| 0 | Discarded downstream frames | 1 | +| 1 | Discarded upstream frames | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.2.9 Forward error correction performance monitoring history data + +This ME collects PM data associated with PON downstream forward error correction (FEC) counters. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the ANI-G ME or an instance of the time and wavelength division multiplexing (TWDM) channel ME. + +#### Attributes + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-G or a TWDM channel. (R, set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) +- Corrected bytes:** This attribute counts the number of bytes that were corrected by the FEC function. (R) (mandatory) (4 bytes) +- Corrected code words:** This attribute counts the code words that were corrected by the FEC function. (R) (mandatory) (4 bytes) +- Uncorrectable code words:** This attribute counts errored code words that could not be corrected by the FEC function. (R) (mandatory) (4 bytes) +- Total code words:** This attribute counts the total received code words. (R) (mandatory) (4 bytes) +- FEC seconds:** This attribute counts seconds during which at least one uncorrectable FEC codeword was received. (R) (mandatory) (2 bytes) + +#### Actions + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | Corrected bytes | 1 | +| 1 | Corrected code words | 2 | +| 2 | Uncorrectable code words | 3 | +| 4 | FEC seconds | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.2.10 Priority queue + +NOTE 1 – In [ITU-T G.984.4], this is called a priority queue-G. + +This ME specifies the priority queue used by a GEM port network CTP in the upstream direction. The upstream priority queue ME is also related to a T-CONT ME. By default, this relationship is fixed by the ONU hardware architecture, but some ONUs may also permit the relationship to be configured through the OMCI, as indicated by the QoS configuration flexibility attribute of the ONU2-G ME. + +In the downstream direction, priority queues are associated with UNIs. Again, the association is fixed by default, but some ONUs may permit the association to be configured through the OMCI. + +If an ONU as a whole contains priority queues, it instantiates these queues autonomously. Priority queues may also be localized to pluggable circuit packs, in which case the ONU creates and deletes them in accordance with circuit pack pre-provisioning and the equipped configuration. + +The OLT can find all the queues by reading the priority queue ME instances. If the OLT tries to retrieve a non-existent priority queue, the ONU denies the get action with an error indication. + +See also Appendix II. + +Priority queues can exist in the ONU core and circuit packs serving both UNI and ANI functions. Therefore, they can be indirectly created and destroyed through cardholder provisioning actions. + +In the upstream direction, the weight attribute permits the configuring of an optional traffic scheduler. Several attributes support back pressure operation, whereby a back-pressure signal is sent backwards and causes the attached terminal to temporarily suspend sending data. + +In the downstream direction, strict priority discipline among the queues serving a given UNI is the default, with priorities established through the related port attribute. If two or more non-empty queues have the same priority, capacity is allocated among them in proportion to their weights. Note that the details of the downstream model differ from those of the upstream model. + +The yellow packet drop thresholds specify the drop probability for a packet that has been marked yellow (drop eligible) by a traffic descriptor or by external equipment such as a residential gateway (RG). If the current average queue occupancy is less than the minimum threshold, the yellow packet drop probability is zero. If the current average queue occupancy is greater than or equal to the maximum threshold, the yellow packet drop probability is one. The yellow drop probability increases linearly between 0 and max\_p as the current average queue occupancy increases from the minimum to the maximum threshold. + +The same model can be configured for green packets, those regarded as being within the traffic contract. + +Drop precedence colour marking indicates the method by which a packet is marked as drop eligible (yellow). For discard eligibility indicator (DEI) and priority code point (PCP) marking, a drop eligible indicator is equivalent to yellow colour; otherwise, the colour is green. For differentiated services code point (DSCP) assured forwarding (AF) marking, the lowest drop precedence is equivalent to green; otherwise, the colour is yellow. + +#### *Relationships* + +One or more instances of this ME are associated with the ONU-G ME to model upstream priority queues if the traffic management option attribute in the ONU-G ME is 0 or 2. + +One or more instances of this ME are associated with a PTP UNI ME as downstream priority queues. Downstream priority queues may or may not be provided for a virtual Ethernet interface point (VEIP). + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The MSB represents the direction (1: upstream, 0: downstream). The 15 LSBs represent a queue ID. The queue ID is numbered in ascending order by the ONU itself. It is strongly encouraged that the queue ID be formulated to simplify finding related queues. One way to do this is to number the queues such that the related port attributes are in ascending order (for the downstream and upstream queues separately). The range of downstream queue ids is 0 to 0x7FFF and the range of upstream queue ids is 0x8000 to 0xFFFF. (R) (mandatory) (2 bytes) + +**Queue configuration option:** This attribute identifies the buffer partitioning policy. The value 1 means that several queues share one buffer of maximum queue size, while the value 0 means that each queue has an individual buffer of maximum queue size. (R) (mandatory) (1 byte) + +**Maximum queue size:** This attribute specifies the maximum size of the queue, in bytes, scaled by the priority queue scale factor attribute of the ONU2-G. (R) (mandatory) (2 bytes) + +NOTE 2 – In this and the other similar attributes of the priority queue ME, some legacy implementations may take the queue scale factor from the GEM block length attribute of the ANI-G ME. This option is discouraged in new implementations. + +**Allocated queue size:** This attribute identifies the allocated size of this queue, in bytes, scaled by the priority queue scale factor attribute of the ONU2-G. (R, W) (mandatory) (2 bytes) + +**Discard-block counter reset interval:** This attribute represents the interval in milliseconds at which the counter resets itself. (R, W) (optional) (2 bytes) + +**Threshold value for discarded blocks due to buffer overflow:** This attribute specifies the threshold for the number of bytes (scaled by the priority queue scale factor attribute of the ONU2-G) discarded on this queue due to buffer overflow. Its value controls the declaration of the block loss alarm. (R, W) (optional) (2 bytes) + +**Related port:** This attribute represents the slot, port/T-CONT and priority information associated with the instance of priority queue ME. This attribute comprises 4 bytes. + +In the upstream direction, the first 2 bytes are the ME ID of the associated T-CONT, the first byte of which is a slot number, the second byte a T-CONT number. In the downstream direction, the first byte is the slot number and the second byte is the port number of the queue's destination port. + +The last 2 bytes represent the priority of this queue. The range of priority is 0 to 0x0FFF. The value 0 indicates the highest priority and 0x0FFF indicates the lowest priority. The priority field is meaningful if multiple priority queues are associated with a T-CONT or traffic scheduler whose scheduling discipline is strict priority. + +(R, W) (mandatory) (4 bytes) + +NOTE 3 – If flexible port configuration is supported, the related port attribute is meaningful only if the traffic scheduler pointer attribute value is null. Otherwise, the related port attribute is ignored. + +NOTE 4 – The related port attribute is read-only, unless otherwise specified by the QoS configuration flexibility attribute of the ONU2-G ME. If port flexibility is supported, the second byte, the port or T-CONT number, may be changed. If priority flexibility is supported, the third and fourth bytes may be changed. The OMCI set command must contain 4 bytes to match the attribute size, but the ONU must ignore all bytes that are not specified to be flexible. + +If flexible configuration is not supported, the ONU should reject an attempt to set the related port with a parameter error result-reason code. + +**Traffic scheduler pointer:** This attribute points to the traffic scheduler ME instance that is associated with this priority queue. This pointer is used when this priority queue is connected with a traffic scheduler. The default value is a null pointer (0). (R, W) (mandatory) (2 bytes) + +NOTE 5 – When the QoS configuration flexibility attribute of the ONU2-G ME allows flexible assignment of the traffic scheduler, the OLT may configure the traffic scheduler pointer to refer to any traffic scheduler in the same slot. + +If traffic scheduler flexibility is not permitted by the QoS configuration flexibility attribute, the OLT may use the traffic scheduler pointer attribute only by pointing to another traffic scheduler ME that is associated with the same T-CONT as the priority queue itself. + +The ONU should reject an attempt to violate these conditions with a parameter error result-reason code. + +**Weight:** This attribute represents weight for WRR scheduling. At a given priority level, capacity is distributed to non-empty queues in proportion to their weights. In the upstream direction, this weight is meaningful if several priority queues are associated with a traffic scheduler or T-CONT whose policy is WRR. In the downstream direction, this weight is used by a UNI in a WRR fashion. Upon ME instantiation, the ONU sets this attribute to 1. (R, W) (mandatory) (1 byte) + +**Back pressure operation:** This attribute enables (0) or disables (1) back pressure operation. Its default value is 0. (R, W) (mandatory) (2 bytes) + +**Back pressure time:** This attribute specifies the duration in microseconds of the back-pressure signal. It can be used as a pause time for an Ethernet UNI. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (4 bytes) + +**Back pressure occur queue threshold:** This attribute identifies the threshold queue occupancy, in bytes, scaled by the priority queue scale factor attribute of the ONU2-G, to start sending a back-pressure signal. (R, W) (mandatory) (2 bytes) + +**Back pressure clear queue threshold:** This attribute identifies the threshold queue occupancy, in bytes, scaled by the priority queue scale factor attribute of the ONU2-G, to stop sending a back-pressure signal. (R, W) (mandatory) (2 bytes) + +**Packet drop queue thresholds:** This attribute is a composite of four 2 byte values, a minimum and a maximum threshold, measured in bytes, scaled by the priority queue scale factor attribute of the ONU2-G, for green and yellow packets. The first value is the minimum green threshold, the queue occupancy below which all green packets are admitted to the queue. The second value is the maximum green threshold, the queue occupancy at or above which all green packets are discarded. The third value is the minimum yellow threshold, the queue occupancy below which all yellow packets are admitted to the queue. The fourth value is the maximum yellow threshold, the queue occupancy at or above which all yellow packets are discarded. The default is that all thresholds take the value of the maximum queue size. (R, W) (optional) (8 bytes) + +**Packet drop max\_p:** This attribute is a composite of two 1 byte values, the probability of dropping a coloured packet when the queue occupancy lies just below the maximum threshold for packets of that colour. The first value is the green packet max\_p, and the second value is the yellow packet max\_p. The probability, max\_p, is determined by adding one to the unsigned value (0..255) of this attribute and dividing the result by 256. The default for each value is 255. (R, W) (optional) (2 bytes) + +**Queue drop w\_q:** This attribute determines the averaging coefficient, w\_q, as described in [b-Floyd]. The averaging coefficient, w\_q, is equal to $2^{-\text{Queue\_drop\_w\_q}}$ . For example, when queue drop\_w\_q has the value 9, the averaging coefficient, w\_q, is $1/512 = 0.001\ 9$ . The default value is 9. (R, W) (optional) (1 byte) + +**Drop precedence colour marking:** This attribute specifies how drop precedence is marked on ingress packets to the priority queue. The default value is 0. + +- 0 No marking (treat all packets as green) +- 1 Internal marking (from traffic descriptor ME) +- 2 DEI [IEEE 802.1ad] +- 3 PCP 8P0D [IEEE 802.1ad] +- 4 PCP 7P1D [IEEE 802.1ad] +- 5 PCP 6P2D [IEEE 802.1ad] +- 6 PCP 5P3D [IEEE 802.1ad] +- 7 DSCP AF class [IETF RFC 2597] + +(R, W) (optional) (1 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|------------------------|-----------------------------------------------------------------------------------------------------------------------| +| 0 | Block loss | Content loss in excess of threshold. The alarm is cleared when the discard block counter reset interval next expires. | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.2.11 Traffic scheduler** + +NOTE 1 – In [ITU-T G.984.4], this ME is called a traffic scheduler-G. + +An instance of this ME represents a logical object that can control upstream GEM packets. A traffic scheduler can accommodate GEM packets after a priority queue or other traffic scheduler and transfer them towards the next traffic scheduler or T-CONT. Because T-CONTs and traffic schedulers are created autonomously by the ONU, the ONU vendor predetermines the most complex traffic handling model it is prepared to support; the OLT may use less than the ONU's full capabilities, but cannot ask for more. See Appendix II for more details. + +After the ONU creates instances of the T-CONT ME, it then autonomously creates instances of the traffic scheduler ME. + +#### *Relationships* + +The traffic scheduler ME may be related to a T-CONT or other traffic schedulers through pointer attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical capability that realizes the traffic scheduler. The first byte is the slot ID of the circuit pack with which this traffic scheduler is associated. For a traffic scheduler that is not associated with a circuit pack, the first byte is 0xFF. The second byte is the traffic scheduler id, assigned by the ONU itself. Traffic schedulers are numbered in ascending order with the range 0..0xFF in each circuit pack or in the ONU core. (R) (mandatory) (2 bytes) + +**T-CONT pointer:** This attribute points to the T-CONT ME instance associated with this traffic scheduler. This pointer is used when this traffic scheduler is connected to the T-CONT directly; It is null (0) otherwise. (R, W) (mandatory) (2 bytes) + +NOTE 2 – This attribute is read-only unless otherwise specified by the QoS configuration flexibility attribute of the ONU2-G ME. If flexible configuration is not supported, the ONU should reject an attempt to set the T-CONT pointer attribute with a parameter error result-reason code. + +**Traffic scheduler pointer:** This attribute points to another traffic scheduler ME instance that may serve this traffic scheduler. This pointer is used when this traffic scheduler is connected to another traffic scheduler; it is null (0) otherwise. (R) (mandatory) (2 bytes) + +**Policy:** This attribute represents scheduling policy. Valid values include: + +- 0 Null +- 1 Strict priority +- 2 WRR (weighted round robin) + +The traffic scheduler derives priority or weight values for its tributary traffic schedulers or priority queues from the tributary MEs themselves. + +(R, W) (mandatory) (1 byte) + +NOTE 3 – This attribute is read-only unless otherwise specified by the QoS configuration flexibility attribute of the ONU2-G ME. If flexible configuration is not supported, the ONU should reject an attempt to set the policy attribute with a parameter error result-reason code. + +**Priority/weight:** This attribute represents the priority for strict priority scheduling or the weight for WRR scheduling. This value is used by the next upstream ME, as indicated by the T-CONT pointer attribute or traffic scheduler pointer attribute. + +If the indicated pointer has policy = strict priority, this value is interpreted as a priority (0 is the highest priority, 255 the lowest). + +If the indicated pointer has policy = WRR, this value is interpreted as a weight. Higher values receive more bandwidth. + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.2.12 Traffic descriptor** + +The traffic descriptor is a profile that allows for traffic management. A priority controlled ONU can point from a MAC bridge port configuration data ME to a traffic descriptor in order to implement traffic management (marking, policing). A rate controlled ONU can point to a traffic descriptor from either a MAC bridge port configuration data ME or a GEM port network CTP to implement traffic management (marking, shaping). + +Packets are determined to be green, yellow or red as a function of the ingress packet rate and the settings in this ME. The colour indicates drop precedence (eligibility), subsequently used by the priority queue ME to drop packets conditionally during congestion conditions. Packet colour is also used by the optional mode 1 DBA status reporting function described in [ITU-T G.984.3]. Red packets are dropped immediately. Yellow packets are marked as drop eligible, and green packets are marked as not drop eligible, according to the egress colour marking attribute. + +The algorithm used to determine the colour marking is specified by the meter type attribute. If [b-IETF RFC 4115] is used, then: + +$$\text{CIR}_{4115} = \text{CIR}$$ + +$$\text{EIR}_{4115} = \text{PIR} - \text{CIR} \text{ (EIR: excess information rate)}$$ + +$$\text{CBS}_{4115} = \text{CBS}$$ + +$$\text{EBS}_{4115} = \text{PBS} - \text{CBS}.$$ + +#### *Relationships* + +This ME is associated with a GEM port network CTP or a MAC bridge port configuration data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**CIR:** This attribute specifies the committed information rate, in bytes per second. The default is 0. (R, W, set-by-create) (optional) (4 bytes) + +**PIR:** This attribute specifies the peak information rate, in bytes per second. The default value 0 accepts the ONU's factory policy. (R, W, set-by-create) (optional) (4 bytes) + +**CBS:** This attribute specifies the committed burst size, in bytes. The default is 0. (R, W, set-by-create) (optional) (4 bytes) + +**PBS:** This attribute specifies the peak burst size, in bytes. The default value 0 accepts the ONU's factory policy. (R, W, set-by-create) (optional) (4 bytes) + +**Colour mode:** This attribute specifies whether the colour marking algorithm considers pre-existing marking on ingress packets (colour-aware) or ignores it (colour-blind). In colour-aware mode, packets can only be demoted (from green to yellow or red, or from yellow to red). The default value is 0. + +- 0 Colour-blind +- 1 Colour-aware + +(R, W, set-by-create) (optional) (1 byte) + +**Ingress colour marking:** This attribute is meaningful in colour-aware mode. It identifies how pre-existing drop precedence is marked on ingress packets. For DEI and PCP marking, a drop eligible indicator is equivalent to yellow; otherwise, the colour is green. For DSCP AF marking, the lowest drop precedence is equivalent to green; otherwise, the colour is yellow. The default value is 0. + +- 0 No marking (ignore ingress marking) +- 2 DEI [IEEE 802.1ad] +- 3 PCP 8P0D [IEEE 802.1ad] +- 4 PCP 7P1D [IEEE 802.1ad] +- 5 PCP 6P2D [IEEE 802.1ad] +- 6 PCP 5P3D [IEEE 802.1ad] +- 7 DSCP AF class [IETF RFC 2597] + +(R, W, set-by-create) (optional) (1 byte) + +**Egress colour marking:** This attribute specifies how drop precedence is to be marked by the ONU on egress packets. If set to internal marking only, the externally visible packet contents are not modified, but the packet is identified in a vendor-specific local way that indicates its colour to the priority queue ME. It is + +possible for the egress marking to differ from the ingress marking; for example, ingress PCP marking could be translated to DEI egress marking. The default value is 0. + +- 0 No marking +- 1 Internal marking only +- 2 DEI [IEEE 802.1ad] +- 3 PCP 8P0D [IEEE 802.1ad] +- 4 PCP 7P1D [IEEE 802.1ad] +- 5 PCP 6P2D [IEEE 802.1ad] +- 6 PCP 5P3D [IEEE 802.1ad] +- 7 DSCP AF class [IETF RFC 2597] + +(R, W, set-by-create) (optional) (1 byte) + +**Meter type:** This attribute specifies the algorithm used to determine the colour of the packet. The default value is 0. + +- 0 Not specified +- 1 [b-IETF RFC 4115] +- 2 [b-IETF RFC 2698] + +(R, set-by-create) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.2.13 GEM port network CTP performance monitoring history data** + +This ME collects GEM frame PM data associated with a GEM port network CTP. Instances of this ME are created and deleted by the OLT. + +NOTE 1 – One might expect to find some form of impaired or discarded frame count associated with a GEM port. However, the only impairment that might be detected at the GEM frame level would be a corrupted GEM frame header. In this case, no part of the header could be considered reliable including the port ID. For this reason, there is no impaired or discarded frame count in this ME. + +NOTE 2 – This ME replaces the GEM port performance history data ME and is preferred for new implementations. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the GEM port network CTP ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the GEM port network CTP. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +- Transmitted GEM frames:** This attribute counts GEM frames transmitted on the monitored GEM port. (R) (mandatory) (4 bytes) +- Received GEM frames:** This attribute counts GEM frames received correctly on the monitored GEM port. A correctly received GEM frame is one that does not contain uncorrectable errors and has a valid header error check (HEC). (R) (mandatory) (4 bytes) +- Received payload bytes:** This attribute counts user payload bytes received on the monitored GEM port. (R) (mandatory) (8 bytes) +- Transmitted payload bytes:** This attribute counts user payload bytes transmitted on the monitored GEM port. (R) (mandatory) (8 bytes) +- Encryption key errors:** This attribute is defined in ITU-T G.987 systems only. It counts GEM frames with erroneous encryption key indexes. If the GEM port is not encrypted, this attribute counts any frame with a key index not equal to 0. If the GEM port is encrypted, this attribute counts any frame whose key index specifies a key that is not known to the ONU. (R) (optional) (4 bytes) + +NOTE 3 – GEM PM ignores idle GEM frames. + +NOTE 4 – GEM PM counts each non-idle GEM frame, whether it contains an entire user frame or only a fragment of a user frame. + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 1 | Encryption key errors | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.2.14 Energy consumption performance monitoring history data** + +This ME collects PM data associated with the ONU's energy consumption. The time spent in various low-power states is recorded as a measure of their utility. Furthermore, the ONU may also include the equivalent of a watt-hour meter, which can be sampled from time to time to measure actual power consumed. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with the ONU in its entirety. + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. The ME ID must be 0. (R, set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +- Threshold data 1/2 ID:** No thresholds are defined for this ME. For uniformity with other PMs, the attribute is retained and shown as mandatory, but it should be set to a null pointer. (R, W, set-by-create) (mandatory) (2 bytes) +- Doze time:** This attribute records the time during which the ONU was in doze energy conservation mode, measured in microseconds. If watchful sleep is enabled in the ONU dynamic power management control ME, the ONU ignores this attribute. (R) (mandatory) (4 bytes) +- Cyclic sleep time:** This attribute records the time during which the ONU was in cyclic sleep energy conservation mode, measured in microseconds. If watchful sleep is enabled in the ONU dynamic power management control ME, the ONU ignores this attribute. (R) (mandatory) (4 bytes) +- Watchful sleep time:** This attribute records the time during which the ONU was in watchful sleep energy conservation mode, measured in microseconds. (R) (mandatory) (4 bytes) +- Energy consumed:** This attribute records the energy consumed by the ONU, measured in millijoules. (R) (optional) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +None. + +### **9.2.15 XG-PON TC performance monitoring history data** + +This ME collects PM data associated with the XG-PON TC layer. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an ANI-G. + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-G. (R, set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) +- PSBd HEC error count:** This attribute counts HEC errors in any of the fields of the downstream physical sync block. (R) (optional) (4 bytes) +- XGTC HEC error count:** This attribute counts HEC errors detected in the XGTC header. In [ITU-T G.9807.1], this attribute is used for framing sublayer (FS) HEC error count management. (R) (optional) (4 bytes) +- Unknown profile count:** This attribute counts the number of grants received whose specified profile was not known to the ONU. (R) (optional) (4 bytes) + +- Transmitted XG-PON encapsulation method (XGEM) frames:** This attribute counts the number of non-idle XGEM frames transmitted. If a service data unit (SDU) is fragmented, each fragment is an XGEM frame and is counted as such. (R) (mandatory) (4 bytes) +- Fragment XGEM frames:** This attribute counts the number of XGEM frames that represent fragmented SDUs, as indicated by the LF bit = 0. (R) (optional) (4 bytes) +- XGEM HEC lost words count:** This attribute counts the number of 4 byte words lost because of an XGEM frame HEC error. In general, all XGTC payload following the error is lost, until the next PSBd event. (R) (optional) (4 bytes) +- XGEM key errors:** This attribute counts the number of downstream XGEM frames received with an invalid key specification. The key may be invalid for several reasons, among which are: +- a) GEM port provisioned for clear text and key index not equal to 00; + - b) no multicast key of the specified key index has been provided via the OMCI for a multicast GEM port; + - c) no unicast key of the specified key index has been successfully negotiated (see clause 15.5 of [ITU-T G.987.3] or clause C.15.5 of [ITU-T G.9807.1] for key negotiation state machine); + - d) GEM port specified to be encrypted and key index = 00; + - e) key index = 11, a reserved value. +- (R) (mandatory) (4 bytes) +- XGEM HEC error count:** This attribute counts the number of instances of an XGEM frame HEC error. (R) (mandatory) (4 bytes) +- Transmitted bytes in non-idle XGEM frames:** This attribute counts the number of transmitted bytes in non-idle XGEM frames. (R) (mandatory) (8 bytes) +- Received bytes in non-idle XGEM frames:** This attribute counts the number of received bytes in non-idle XGEM frames. (R) (optional) (8 bytes) +- Loss of downstream synchronization (LODS) event count:** This attribute counts the number of state transitions from O5.1 to O6. (R) (optional) (4 bytes) +- LODS event restored count:** This attribute counts the number of LODS cleared events. (R) (optional) (4 bytes) +- ONU reactivation by LODS events:** This attribute counts the number of LODS events resulting in ONU reactivation without synchronization being reacquired. (R) (optional) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 1 | PSBd HEC error count | 1 | +| 2 | XGTC HEC error count | 2 | +| 3 | Unknown profile count | 3 | +| 4 | XGEM HEC loss count | 4 | +| 5 | XGEM key errors | 5 | +| 6 | XGEM HEC error count | 6 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.2.16 XG-PON downstream management performance monitoring history data + +This ME collects PM data associated with the XG-PON TC layer. It collects counters associated with downstream PLOAM and OMCI messages. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an ANI-G. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-G. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**PLOAM message integrity check (MIC) error count:** This attribute counts MIC errors detected in downstream PLOAM messages, either directed to this ONU or broadcast to all ONUs. (R) (optional) (4 bytes) + +**Downstream PLOAM messages count:** This attribute counts PLOAM messages received, either directed to this ONU or broadcast to all ONUs. (R) (optional) (4 bytes) + +**Profile messages received:** This attribute counts the number of profile messages received, either directed to this ONU or broadcast to all ONUs. In [ITU-T G.9807.1], this attribute is used for received burst\_profile message count. (R) (optional) (4 bytes) + +**Ranging\_time messages received:** This attribute counts the number of ranging\_time messages received, either directed to this ONU or broadcast to all ONUs. (R) (mandatory) (4 bytes) + +**Deactivate\_ONU-ID messages received:** This attribute counts the number of deactivate\_ONU-ID messages received, either directed to this ONU or + +broadcast to all ONUs. Deactivate\_ONU-ID messages do not reset this counter. (R) (optional) (4 bytes) + +**Disable\_serial\_number messages received:** This attribute counts the number of disable\_serial\_number messages received, whose serial number specified this ONU. (R) (optional) (4 bytes) + +**Request\_registration messages received:** This attribute counts the number of request\_registration messages received. (R) (optional) (4 bytes) + +**Assign\_alloc-ID messages received:** This attribute counts the number of assign\_alloc-ID messages received. (R) (optional) (4 bytes) + +**Key\_control messages received:** This attribute counts the number of key\_control messages received, either directed to this ONU or broadcast to all ONUs. (R) (optional) (4 bytes) + +**Sleep\_allow messages received:** This attribute counts the number of sleep\_allow messages received, either directed to this ONU or broadcast to all ONUs. (R) (optional) (4 bytes) + +**Baseline OMCI messages received count:** This attribute counts the number of OMCI messages received in the baseline message format. (R) (optional) (4 bytes) + +**Extended OMCI messages received count:** This attribute counts the number of OMCI messages received in the extended message format. (R) (optional) (4 bytes) + +**Assign\_ONU-ID messages received:** This attribute counts the number of assign\_ONU-ID messages received since the last re-boot. (R) (optional) (4 bytes) + +**OMCI MIC error count:** This attribute counts MIC errors detected in OMCI messages directed to this ONU. (R) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 1 | PLOAM MIC error count | 1 | +| 2 | OMCI MIC error count | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.2.17 XG-PON upstream management performance monitoring history data** + +This ME collects PM data associated with the XG-PON TC layer. It counts upstream PLOAM messages transmitted by the ONU. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an ANI-G. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-G. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** No thresholds are defined for this ME. For uniformity with other PM, the attribute is retained and shown as mandatory, but it should be set to a null pointer. (R, W, set-by-create) (mandatory) (2 bytes) + +**Upstream PLOAM message count:** This attribute counts PLOAM messages transmitted upstream, excluding acknowledge messages. (R) (optional) (4 bytes) + +**Serial\_number\_ONU message count:** This attribute counts Serial\_number\_ONU PLOAM messages transmitted. (R) (optional) (4 bytes) + +**Registration message count:** This attribute counts Registration PLOAM messages transmitted. (R) (optional) (4 bytes) + +**Key\_report message count:** This attribute counts key\_report PLOAM messages transmitted. (R) (optional) (4 bytes) + +**Acknowledge message count:** This attribute counts acknowledge PLOAM messages transmitted. It includes all forms of acknowledgement (AK), including those transmitted in response to a PLOAM grant when the ONU has nothing to send. (R) (optional) (4 bytes) + +**Sleep\_request message count:** This attribute counts sleep\_request PLOAM messages transmitted. (R) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +None. + +### **9.2.18 L2 multicast GEM interworking termination point** + +An instance of this ME represents a point in an EPON ONU where a multicast service interworks with the GEM layer. At this point, a multicast bit stream is forwarded. + +Instances of this ME are created and deleted by the OLT. + +#### **Multicast interworking GEM modes of operation** + +The default multicast operation of the EPON is one in which all the multicast content streams are carried in one PON layer connection (GEM port). This connection is then specified by the multicast MAC address filtering table. According to this table, the ONU filters the traffic based on Ethernet MAC addresses. The associated GEM port network CTP ME specifies the GEM port-ID that supports all multicast connections. + +In the default multicast operation, all multicast content streams are placed in one PON layer connection (GEM port). The OLT sets up a completely conventional model, a pointer from the L2 multicast GEM IW TP to a GEM port network CTP. The OLT configures the GEM port-ID of the GEM port network CTP into the multicast MAC address filtering table attribute, along with the other table fields that specify multicast destination MAC addresses for filtering. The ONU accepts the entire + +multicast stream through the designated GEM port and then filters the traffic based on Ethernet MAC address. + +An optional multicast configuration supports separate multicast streams carried over separate PON layer connections, i.e., on separate GEM ports. This permits the ONU to filter multicast streams at the GEM level, which is hardware efficient, while ignoring other multicast streams that may be of interest to other ONUs on the PON. + +After configuring the explicit model for the first multicast GEM port, the OLT supports multiple multicast GEM ports by configuring additional entries into the multicast MAC address filtering table, entries with different GEM port-IDs. The OMCI model is defined such that these ports are implicitly grouped together and served by the single explicit GEM port network CTP. No additional GEM network CTPs need be created or linked for the additional GEM ports. + +Several L2 multicast GEM IW TPs can exist, each linked to separate bridge ports or mappers, to serve different communities of interest in a complex ONU. + +#### Discovery of multicast support + +The OLT uses the L2 multicast GEM IW TP entity as the means to discover the ONU's multicast capability. This entity is mandatory if multicast is supported by an EPON ONU. If the OLT attempts to create this entity on an ONU that does not support multicast, the create command fails. The create command also fails if the OLT attempts to exploit optional features that the ONU does not support, e.g., in attempting to create multiple L2 multicast GEM IW TPs. + +This ME is defined by similarity to the unicast GEM IW TP, and a number of its attributes are not meaningful in a multicast context. These attributes are set to 0 and not used, as indicated in the following. + +#### *Relationships* + +An instance of this ME exists for each layer 2 multicast community of interest. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0xFFFF is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**GEM port network CTP connectivity pointer:** This attribute points to an instance of the GEM port network CTP that is associated with this L2 multicast GEM IW TP. (R, W, set-by-create) (mandatory) (2 bytes) + +**Interworking option:** This attribute identifies the type of non-GEM function that is being interworked. The option can be: + +- 0 This value is a "no-op" or "don't care". It should be used when the L2 multicast GEM IW TP is associated with several functions of different types. It can optionally be used in all cases, since the necessary information is available elsewhere. The previous code points are retained for backward compatibility: +- 1 MAC bridged LAN +- 3 Reserved +- 5 IEEE 802.1p mapper + +(R, W, set-by-create) (mandatory) (1 byte) + +**Service profile pointer:** This attribute is set to 0 and not used. For backward compatibility, it may also be set to point to a MAC bridge service profile or IEEE 802.1p mapper service profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Not used 1:** This attribute is set to 0 and not used. (R, W, set-by-create) (mandatory) (2 bytes) + +**PPTP counter:** This attribute represents the number of instances of PPTP MEs associated with this instance of the L2 multicast GEM IW TP. This attribute conveys no information that is not available elsewhere; it may be set to 0xFF and not used. (R) (optional) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**GAL profile pointer:** This attribute is set to 0 and not used. For backward compatibility, it may also be set to point to a GAL Ethernet profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Not used 2:** This attribute is set to 0 and not used. (R, W, set-by-create) (mandatory) (1 byte) + +**Multicast MAC address filtering capability:** With this attribute, the ONU reports to the OLT its supported multicast MAC address registration methods and the maximum number of filtering table entries at the ONU. + +| | | +|------------------------------------------------|---------| +| Multicast MAC address registration method | 1 byte | +| Maximum number of static registration entries | 2 bytes | +| Maximum number of dynamic registration entries | 2 bytes | + +The bits of the multicast MAC address registration method field are assigned as follows: + +| Bit | Name | Setting | +|---------|----------------------------------|----------------------------------| +| 1 (LSB) | Static MAC address registration | 0: not supported
1: supported | +| 2 | Dynamic MAC address registration | 0: not supported
1: supported | +| 3..8 | Reserved | 0 | + +(R) (mandatory) (5 bytes) + +**Multicast MAC address registration mode:** This attribute allows the OLT to specify the multicast MAC address registration method. + +- 0 Disable multicast MAC address filtering +- 1 Static MAC address registration +- 2 Dynamic MAC address registration + +In L2-based multicast operation, the OLT handles the Internet group management protocol/multicast listener discovery (IGMP/MLD) protocol of the network and the ONU filters the multicast data stream as instructed by the OLT. ONU may support the static MAC address registration method or the dynamic MAC address registration method according to its filter implementation. + +In the static MAC address registration method, the OLT provisions all available multicast addresses at the ONU. For each of the available addresses, the OLT also provides a status flag, which designates either pass or drop. + +In the dynamic MAC address registration method, the OLT provisions multicast addresses allowed at the ONU. A frame whose DA matches the provisioned MAC destination group address is forwarded to the output port. Frames whose DA is a MAC group address (except for the broadcast address) and does not match any of the provisioned allowed MAC group addresses are discarded. The target range of MAC address that is handled in this filtering mode is 0x01-00-5E-00-00-00 through 0x01-00-5E-7F-FF-FF for IPv4 multicast traffic and 0x33-33-00-01-00-00 through 33-33-FF-FF-FF-FF for IPv6 multicast traffic. + +(R, W) (mandatory) (1 byte) + +**Aging timer:** This attribute sets the aging timer value in seconds that is called the multicast address listener interval in IGMP/MLD specifications. The ONU starts or restarts the timer when an entry is added or overwritten in the multicast MAC address filtering table. If the timer expires, the ONU changes the corresponding pass/drop flag to drop in case of static MAC address registration, or removes the corresponding Multicast destination MAC address entry in case of dynamic MAC address registration. The configurable value is 0 to 0x0F-FF-EF seconds and is common for all MAC address entries. The aging timer can be separately enabled or disabled in each multicast MAC address filtering table entry. + +(R, W) (optional) (3 bytes) + +**Multicast MAC address filtering table:** This attribute is a list that specifies multicast MAC address filtering configurations. Each entry contains the following. + +| | | +|-----------------------------------|---------| +| GEM port-ID | 2 bytes | +| Secondary key | 2 bytes | +| Filter | 1 byte | +| Multicast destination MAC address | 6 bytes | + +The first 4 bytes of each entry are treated as a key into the list. The secondary key shows the entry number for a given GEM port. + +The bits of the filter byte are assigned as follows. + +| Bit | Name | Setting | +|---------|------------|---------------------------------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Pass/drop | 0: drop
1: pass | +| 2 | Aging | 0: disabled
1: enabled | +| 3..6 | Reserved | 0 | +| 7..8 | Add/remove | 10: Clear entire table (set operation)
00: Remove this entry (set operation)
01: Add/overwrite this entry (set operation) | + +Upon ME instantiation, the ONU sets this attribute to an empty table. + +(R, W) (mandatory) (11*N* bytes, where *N* is the number of entries in the list.) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..5 | N/A | | +| 6 | Op state | Operational state change | +| 7..12 | N/A | | +| 13..16 | Reserved | | + +### 9.2.19 ANI-E + +This ME organizes data associated with each access network interface supported by an EPON ONU. The ONU automatically creates one instance of this ME for each PON physical port. + +#### *Relationships* + +An instance of this ME is associated with each instance of a physical PON interface. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value indicates the physical position of the PON interface. The first byte is the slot ID, defined in clause 9.1.5. The second byte is the port ID. (R) (mandatory) (2 bytes) + +**Encryption and FEC capability:** This attribute is used by the OLT to read the encryption and FEC capabilities. The most significant 4 bits denote the encryption capability and the least significant 4 bits denote the FEC capability. It is noted that downstream encryption is mandatory. + +The coding for the most significant field is specified as follows: + +0x0: upstream encryption is not supported (1G-EPON ONU) + +0x1: upstream encryption is supported (1G-EPON ONU) + +0x2: encryption is activated as part of [IEEE 802.1X] authentication/key establishment (10G/10G-EPON ONU or 10G/1G-EPON ONU) + +The coding for the least significant field is specified as follows: + +0x0: FEC is not supported for 1G link (1G-EPON ONU or 10G/1G-EPON ONU) + +0x1: FEC is supported for 1G link (1G-EPON ONU or 10G/1G-EPON ONU) + +0x2: mandatory FEC capability (10G/10G-EPON ONU) + +(R) (optional) (1 byte) + +**Encryption and FEC configuration:** This attribute specifies the encryption and FEC operations. The most significant 4 bits designate the upstream encryption and the least significant 4 bits designate the FEC operation. + +The coding for the most significant field is specified as follows: + +0x0: disable upstream encryption for 1G-EPON ONU + +0x1: enable upstream encryption for 1G-EPON ONU + +The coding for the least significant field is specified as follows: + +0x0: disable FEC for 1G link + +0x1: enable FEC for 1G link + +A 10G/10G-EPON ONU and a 10G/1G-EPON ONU ignores the most significant field. A 10G/10G-EPON ONU also ignores the least significant field. + +(R, W) (optional) (1 byte) + +**ONU capability to configure number of queue sets:** This attribute specifies the ONU's capability to configure the number of queue sets. The ONU reports the highest value that it supports for the minimum number of queue sets, and the OLT can configure the minimum number of queue sets to a number that is equal to or less than the reported number. + +The coding is specified as follows: + +- 0: reserved +- 1: not supported +- 2: supported: the highest value for minimum number of queue sets is 2 +- 3: supported: the highest value for minimum number of queue sets is 3 +- 4: supported: the highest value for minimum number of queue sets is 4 + +(R) (mandatory) (1 byte) + +NOTE – The queue set is one of fields in the REPORT MPCPDU (multi-point control protocol data unit) and consists of eight queue reports, as defined in clauses 64.3.6.2 and 77.3.6.2 of [IEEE 802.3]. + +**Number of queue sets:** This attribute specifies the maximum number of queue sets and the minimum number of queue sets to be used by the given ONU to generate the REPORT MPCPDU. The most significant 4 bits denote the maximum number of queue sets and the least significant 4 bits denote the minimum number of queue sets. The admissible values for each field are 0x01, 0x02, 0x03 and 0x04 if they do not exceed the ONU capability. (R, W) (mandatory) (1 byte) + +NOTE – This attribute is read-only, if the ONU capability to configure the number of queue sets attribute indicates code point 1. If flexible configuration is not supported, the ONU should reject an attempt to set it with a parameter error result-reason code. + +**Threshold configuration:** This attribute specifies the threshold type and the threshold ordering to be used by the given ONU to generate the REPORT MPCPDU. The most significant 4 bits denote the threshold type and the least significant 4 bits denote the threshold ordering. + +The coding for the most significant field is specified as follows. Code 0 is valid in the get operation. + +- 0x0: not configurable (ONU supports aggregated threshold type only) +- 0x1: aggregated threshold +- 0x2: dedicated threshold + +The coding for the least significant field is specified as follows. Code 0 is valid in the get operation. + +- 0x0: not configurable (ONU supports descending order only) +- 0x1: descending order +- 0x2: ascending order + +(R, W) (mandatory) (1 byte) + +**ONU capability to configure threshold starting point:** This attribute specifies the ONU capability to configure the threshold starting point. + +The coding is specified as follows. + +- 0: supported +- 1: not supported + +(R) (mandatory) (1 byte) + +**Threshold starting point:** This attribute specifies the threshold starting point to be used by the given ONU to generate the REPORT MPCPDU. + +The coding is specified as follows. + +- 0: end of granted packet +- 1: buffer head + +(R, W) (mandatory) (1 byte) + +**Number of queue threshold sets:** This attribute specifies the number of queue threshold sets to be used by the given ONU to generate the REPORT MPCPDU. This number covers the queue set used to report the total queue length. The admissible values for this field are 1, 2, 3 and 4. (R, W) (mandatory) (1 byte) + +**Aggregated threshold table:** This attribute is a list that specifies the value of aggregated threshold, in time quanta (TQs), associated with the queues that are to be present in the REPORT MPCPDU generated by the ONU if the threshold type is aggregated threshold. The queue occupancy included in the queue No. *n* report field in the REPORT MPCPDU is always less than or equal to the provisioned value of the No. *n* threshold, while observing the frame boundaries. + +Each list entry is as follows: + +- threshold index number: 0-3 (1 byte) +- aggregated threshold value (2 bytes) + +A set action to a particular value overwrites any existing entry with the same first 1 byte. If the last 2 bytes of a set command are all zero, that entry is cleared from the list. Moreover, if the first 1 byte of a set is 0xFF, the entire table is cleared. + +(R, W) (mandatory) ( $3N$ bytes, where *N* is the number of entries in the table) + +**Dedicated threshold table:** This attribute is a list that specifies the value of dedicated threshold, in TQs, to be associated with the given queue within the particular queue threshold set if the threshold type is dedicated threshold. + +Each list entry is as follows: + +- index number (1 byte) + - bits 7-4: queue set index number 0-3 + - bits 3-0: threshold index number 0-7 +- dedicated threshold value (2 bytes) + +A set action to a particular value overwrites any existing entry with the same first 1 byte. If the last 2 bytes of a set command are all zero, that entry is cleared from the list. Moreover, if the first 1 byte of a set is 0xFF, the entire table is cleared. + +(R, W) (mandatory) ( $3N$ bytes, where *N* is the number of entries in the table) + +**ONU capability to configure queue service procedure:** This attribute specifies the ONU capability to configure queue service procedure. + +The coding is specified as follows: + +- 0: supported +- 1: not supported + +(R) (mandatory) (1 byte) + +**Ability to set queue service procedure:** This attribute specifies which type(s) of procedure are supported by the ONU. + +The bit map is specified as follows: + +- | | | +|------------------------------|------------------| +| bit 1 (LSB): Threshold-first | 0: supported | +| | 1: not supported | +| bit 2: Priority-first | 0: supported | +| | 1: not supported | + +bit 3: Strict priority + +0: supported + +1: not supported + +(R) (mandatory) (1 bytes) + +**Queue service procedure:** This attribute specifies the threshold starting point to be used by the given ONU to generate the REPORT MPCPDU. + +The coding is specified as follows: + +0: Threshold-first + +1: Priority-first + +2: Strict priority + +(R, W) (mandatory) (1 byte) + +**Holdover time out:** This attribute is used by the OLT to configure the holdover timer in the ONU. The value is expressed in milliseconds. The default value is 200 ms. + +(R, W) (optional) (4 bytes) + +**TLoS\_optical:** This attribute is used by the OLT to configure the TLoS\_optical (time threshold of optical signal loss) value, which is the period of time that has to elapse before the ONU moves to the holdover state if no optical signal is detected. The value is expressed in milliseconds. The default value is 200 ms. + +(R, W) (optional) (2 bytes) + +**TLoS\_MAC:** This attribute is used by the OLT to configure the TLoS\_MAC (time threshold of GATE MPCPDU loss) value, which is the period of time that has to elapse before the ONU moves to the holdover state if no GATE MPCPDU is received. This parameter corresponds to the gate\_timeout as specified in clauses 64.3.5.1 and 77.3.5.1 of [IEEE 802.3]. The value is expressed in milliseconds. The default value is 50 ms. + +(R, W) (optional) (2 bytes) + +#### *Actions* + +Get, set, get-next + +Set table (optional) + +Test: Test the ANI-E (optional). The test action can be used to collect some of the PM data for a small form factor (SFF)-8472 compliant transceiver on the ANI side, such as optical transceiver unit temperature, optical transceiver unit supply voltage, optical transmitter unit bias current, optical transceiver unit output power and optical transceiver unit input power. Test and test result messages are defined in Annex A. + +#### *Notifications* + +**Test result:** Test results are reported via a test message if the test is invoked by a test command from the OLT. + +### **9.2.20 EPON downstream performance monitoring configuration** + +This ME represents window sizes and threshold values for EPON downstream PM operations which are defined in [IEEE 802.3] as: errored symbol period, errored frame, errored frame period and errored frame seconds summary. + +The EPON ONU automatically instantiates an instance of this ME for each ANI-E. + +#### *Relationships* + +An instance of this ME is associated with an ANI-E. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-E. (R, set-by-create) (mandatory) (2 bytes) + +**Errored symbol period window:** This attribute specifies the number of symbols in the measurement period, as defined in clause 57.5.3.1 of [IEEE 802.3]. (R, W) (optional) (8 bytes) + +**Errored symbol period threshold:** This attribute specifies the threshold of errored symbols for generating an event report, as defined in clause 57.5.3.1 of [IEEE 802.3]. (R, W) (optional) (8 bytes) + +**Errored frame window:** This attribute specifies the duration in units of 100 ms of the measurement period, as defined in clause 57.5.3.2 of [IEEE 802.3]. (R, W) (optional) (2 bytes) + +**Errored frame threshold:** This attribute specifies the threshold of errored frames for generating an event report, as defined in clause 57.5.3.2 of [IEEE 802.3]. (R, W) (optional) (4 bytes) + +**Errored frame period window:** This attribute specifies the duration in terms of frames of the measurement period, as defined in clause 57.5.3.3 of [IEEE 802.3]. (R, W) (optional) (4 bytes) + +**Errored frame period threshold:** This attribute specifies the threshold of errored frames for generating an event report, as defined in clause 57.5.3.3 of [IEEE 802.3]. (R, W) (optional) (4 bytes) + +**Errored frame seconds summary window:** This attribute specifies the duration in units of 100 ms of the measurement period, as defined in clause 57.5.3.4 of [IEEE 802.3]. (R, W) (optional) (2 bytes) + +**Errored frame seconds summary threshold:** This attribute specifies the threshold of errored frame seconds for generating an event report, as defined in clause 57.5.3.4 of [IEEE 802.3]. (R, W) (optional) (2 bytes) + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.2.21 This clause is intentionally left blank** + +### **9.2.22 Enhanced FEC performance monitoring history data** + +This ME collects PM data associated with PON downstream FEC counters for XGS-PON and subsequent ITU-T PON systems. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the ANI-G ME or an instance of the TWDM channel ME. + +#### Attributes + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-G or a TWDM channel. (R, set-by-create) (mandatory) (2 bytes) +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 64 bit ID:** This attribute points to an instance of the threshold data 64 bit ME that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) +- Corrected bytes:** This attribute counts the number of bytes that were corrected by the FEC function. (R) (mandatory) (8 bytes) +- Corrected code words:** This attribute counts the code words that were corrected by the FEC function. (R) (mandatory) (8 bytes) +- Uncorrectable code words:** This attribute counts errored code words that could not be corrected by the FEC function. (R) (mandatory) (8 bytes) +- Total code words:** This attribute counts the total received code words. (R) (mandatory) (8 bytes) +- FEC errored seconds:** This attribute counts seconds during which at least one uncorrectable FEC codeword was received. (R) (mandatory) (2 bytes) + +#### Actions + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | Corrected bytes | 1 | +| 1 | Corrected code words | 2 | +| 2 | Uncorrectable code words | 3 | +| 4 | FEC seconds | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 64 bit managed entity. + +### 9.2.23 Enhanced TC performance monitoring history data + +This ME collects PM data associated with the XGS-PON and subsequent ITU-T PON systems' TC layer. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an ANI-G. + +#### Attributes + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the ANI-G. (R, set-by-create) (mandatory) (2 bytes) + +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 64 bit ID:** This attribute points to an instance of the threshold data 64 bit ME that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) +- PSBd HEC error count:** This attribute counts HEC errors in any of the fields of the downstream physical sync block. (R) (optional) (4 bytes) +- XGTC HEC error count:** This attribute counts HEC errors detected in the XGTC header. In [ITU-T G.9807.1], this attribute is used for FS HEC error count management. (R) (optional) (4 bytes) +- Unknown profile count:** This attribute counts the number of grants received whose specified profile was not known to the ONU. (R) (optional) (4 bytes) +- Transmitted XGEM frames:** This attribute counts the number of non-idle XGEM frames transmitted. If an SDU is fragmented, each fragment is an XGEM frame and is counted as such. (R) (mandatory) (8 bytes) +- Fragment XGEM frames:** This attribute counts the number of XGEM frames that represent fragmented SDUs, as indicated by the LF bit = 0. (R) (optional) (8 bytes) +- XGEM HEC lost words count:** This attribute counts the number of 4 byte words lost because of an XGEM frame HEC error. In general, all XGTC payload following the error is lost, until the next PSBd event. (R) (optional) (8 bytes) +- XGEM key errors:** This attribute counts the number of downstream XGEM frames received with an invalid key specification. The key may be invalid for several reasons, among which are: +- GEM port provisioned for clear text and key index not equal to 00; + - no multicast key of the specified key index has been provided via the OMCI for a multicast GEM port; + - no unicast key of the specified key index has been successfully negotiated (see clause 15.5 of [ITU-T G.987.3] or clause C.15.5 of [ITU-T G.9807.1] for key negotiation state machine); + - GEM port specified to be encrypted and key index = 00; + - key index = 11, a reserved value. +- (R) (mandatory) (8 bytes) +- XGEM HEC error count:** This attribute counts the number of instances of an XGEM frame HEC error. (R) (mandatory) (8 bytes) +- Transmitted bytes in non-idle XGEM frames:** This attribute counts the number of transmitted bytes in non-idle XGEM frames. (R) (mandatory) (8 bytes) +- Received bytes in non-idle XGEM frames:** This attribute counts the number of received bytes in non-idle XGEM frames. (R) (optional) (8 bytes) +- LODS event count:** This attribute counts the number of state transitions from O5.1 to O6. (R) (optional) (4 bytes) +- LODS event restored count:** This attribute counts the number of LODS cleared events. (R) (optional) (4 bytes) +- ONU reactivation by LODS events:** This attribute counts the number of LODS events resulting in ONU reactivation without synchronization being reacquired. (R) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|---------------------|---------------------------------|---------------------------------------------| +| 1 | PSBd HEC error count | 1 | +| 2 | XGTC HEC error count | 2 | +| 3 | Unknown profile count | 3 | +| 4 | XGEM HEC loss count | 4 | +| 5 | XGEM key errors | 5 | +| 6 | XGEM HEC error count | 6 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 64 bit managed entity. + +## **9.3 Layer 2 data services** + +As outlined in Figure 9.3-1, this clause describes MEs that support layer 2 services, independent of the exact nature of the UNI (Ethernet, MoCA, xDSL). Possible UNIs are described in their own clauses. + +![Diagram of managed entities that support layer 2, showing relationships between MAC bridge, VLAN, Dot1X, and Dotlag components.](d6b0963170ed3d0ed9c5bfaccec452e3_img.jpg) + +The diagram illustrates the managed entities that support layer 2, organized into several functional groups with their respective relationships: + +- MAC Bridge Service Profile (9.3.1):** + - Pointed to by: GEM interworking TP, Multicast GEM interworking TP. + - Points to: 9.3.3 (MAC bridge PM history data), 9.3.9 (MAC bridge port PM history data), 9.3.2 (MAC bridge configuration data), 9.3.5 (MAC bridge port designation data), 9.3.6 (MAC bridge port filter table data), 9.3.7 (MAC bridge port filter pre-assign table), 9.3.8 (MAC bridge port bridge table data), 9.3.11 (VLAN tagging filter data), 9.3.33 (MAC bridge port ICMPv6 process pre-assign table), 9.3.17 (Radius PM history data), 9.3.18 (Dot1 rate limiter). +- MAC Bridge Port Config Data (9.3.4):** + - Pointed to by: (Extended) VLAN tagging operation config data. + - Points to: TP, Outbound TD, Inbound TD, 9.3.10 (802.1p mapper service profile), 9.3.12 (VLAN tagging operation config data), 9.3.13 (Extended VLAN tagging operation config data), 9.3.14 (Dot1X port extension package), 9.3.16 (Dot1X PM history data), 9.3.15 (Dot1X configuration profile). +- Dot1X Port Extension Package (9.3.14):** Points to UNI. +- Dot1X PM History Data (9.3.16):** Points to UNI. +- Dot1X Configuration Profile (9.3.15):** Points to 9.3.18 (Dot1 rate limiter). +- Dot1 Rate Limiter (9.3.18):** Points to MAC bridge service profile or 802.1p mapper service profile, 3x traffic descriptors. +- Dotlag Maintenance Domain (9.3.19):** Points to 9.3.20 (Dotlag maintenance association). +- Dotlag Maintenance Association (9.3.20):** Points to 9.3.21 (Dotlag default MD level), 9.3.22 (Dotlag MEP), 9.3.24 (Dotlag MEP CCM database). +- Dotlag MEP (9.3.22):** Points to MAC bridge port config data or 802.1p mapper service profile. +- Dotlag MEP CCM Database (9.3.24):** Points to 9.3.23 (Dotlag MEP status). +- Dotlag MEP Status (9.3.23):** Points to 9.3.22 (Dotlag MEP). +- Multicast Subscriber Monitor (9.3.29):** Linked to MAC bridge port config data or 802.1p mapper service profile. +- Multicast Subscriber Config Info (9.3.28):** Linked to MAC bridge port config data or 802.1p mapper service profile. +- Multicast Operations Profile (9.3.27):** Points to 9.3.28 (multicast subscriber config info). + +Common TP Interwork TP 0.7 UNI, IW TP or IPv4/v6 host UNI, IW TP or IPv4/v6 host + +Diagram of managed entities that support layer 2, showing relationships between MAC bridge, VLAN, Dot1X, and Dotlag components. + +Figure 9.3-1 – Managed entities that support layer 2 + +### 9.3.1 MAC bridge service profile + +This ME models a MAC bridge in its entirety; any number of ports may be associated with the bridge through pointers to the MAC bridge service profile ME. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +Bridge ports are modelled by MAC bridge port configuration data MEs, any number of which can point to a MAC bridge service profile. The real-time status of the bridge is available from an implicitly linked MAC bridge configuration data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The first byte is the slot ID. In an integrated ONU, this value is 0. The second byte is the bridge group ID. (R, set-by-create) (mandatory) (2 bytes) + +**Spanning tree ind:** The Boolean value true specifies that a spanning tree algorithm is enabled. The value false disables (rapid) spanning tree. (R, W, set-by-create) (mandatory) (1 byte) + +**Learning ind:** The Boolean value true specifies that bridge learning functions are enabled. The value false disables bridge learning. (R, W, set-by-create) (mandatory) (1 byte) + +**Port bridging ind:** The Boolean value true specifies that bridging between UNI ports is enabled. The value false disables local bridging. (R, W, set-by-create) (mandatory) (1 byte) + +**Priority:** This attribute specifies the bridge priority in the range 0..65535. The value of this attribute is copied to the bridge priority attribute of the associated MAC bridge configuration data ME. (R, W, set-by-create) (mandatory) (2 bytes) + +**Max age:** This attribute specifies the maximum age (in 256ths of a second) of received protocol information before its entry in the spanning tree listing is discarded. The range is 0x0600 to 0x2800 (6..40 s) in accordance with [IEEE 802.1D]. (R, W, set-by-create) (mandatory) (2 bytes) + +**Hello time:** This attribute specifies how often (in 256ths of a second) the bridge advertises its presence via hello packets, while acting as a root or attempting to become a root. The range is 0x0100 to 0x0A00 (1..10 s). (R, W, set-by-create) (mandatory) (2 bytes) + +NOTE – [IEEE 802.1D] specifies the compatibility range for hello time to be 1..2 s. + +**Forward delay:** This attribute specifies the forwarding delay (in 256ths of a second) when the bridge acts as the root. The range is 0x0400 to 0x1E00 (4..30 s) in accordance with [IEEE 802.1D]. (R, W, set-by-create) (mandatory) (2 bytes) + +**Unknown MAC address discard:** The Boolean value true specifies that MAC frames with unknown DAs be discarded. The value false specifies that such frames be forwarded to all allowed ports. (R, W, set-by-create) (mandatory) (1 byte) + +**MAC learning depth:** This attribute specifies the maximum number of UNI MAC addresses to be learned by the bridge. The default value 0 specifies that there is no administratively imposed limit. (R, W, set-by-create) (optional) (1 byte) + +**Dynamic filtering ageing time:** This attribute specifies the age of dynamic filtering entries in the bridge database, after which unrefreshed entries are discarded. In accordance with clause 7.9.2 of [IEEE 802.1D] and clause 8.8.3 of [IEEE + +802.1Q], the range is 10..1 000 000 s, with a resolution of 1 s and a default of 300 s. The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.3.2 MAC bridge configuration data** + +This ME organizes status data associated with a MAC bridge. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a MAC bridge service profile. + +#### *Relationships* + +This ME is associated with one instance of a MAC bridge service profile. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge service profile. (R) (mandatory) (2 bytes) + +**Bridge MAC address:** This attribute indicates the MAC address used by the bridge. The ONU sets this attribute to a value based on criteria beyond the scope of this Recommendation, e.g., factory settings. (R) (mandatory) (6 bytes) + +**Bridge priority:** This attribute reports the priority of the bridge. The ONU copies this attribute from the priority attribute of the associated MAC bridge service profile. The value of this attribute changes with updates to the MAC bridge service profile priority attribute. (R) (mandatory) (2 bytes) + +**Designated root:** This attribute identifies the bridge at the root of the spanning tree. It comprises bridge priority (2 bytes) and MAC address (6 bytes). (R) (mandatory) (8 bytes) + +**Root path cost:** This attribute reports the cost of the best path to the root as seen from this bridge. Upon ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (4 bytes) + +**Bridge port count:** This attribute records the number of ports linked to this bridge. (R) (mandatory) (1 byte) + +**Root port num:** This attribute contains the port number that has the lowest cost from the bridge to the root bridge. The value 0 means that this bridge is itself the root. Upon ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (2 bytes) + +**Hello time:** This attribute is the hello time received from the designated root, the interval (in 256ths of a second) between HELLO packets. Its range is 0x0100 to 0x0A00 (1..10 s). (R) (optional) (2 bytes) + +NOTE – [IEEE 802.1D] specifies the compatibility range for hello time to be 1..2 s. + +**Forward delay:** This attribute is the forwarding delay time received from the designated root (in 256ths of a second). Its range is 0x0400 to 0x1E00 (4..30 s) in accordance with [IEEE 802.1D]. (R) (optional) (2 bytes) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.3.3 MAC bridge performance monitoring history data** + +This ME collects PM data associated with a MAC bridge. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +This ME is associated with an instance of a MAC bridge service profile. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge service profile. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Bridge learning entry discard count:** This attribute counts forwarding database entries that have been or would have been learned, but were discarded or replaced due to a lack of space in the database table. When used with the MAC learning depth attribute of the MAC bridge service profile, the bridge learning entry discard count may be particularly useful in detecting MAC spoofing attempts. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|----------------------------------------------------------------------------------------------------------------------------|-------------------------------|--------------------------------------| +| 0 | Bridge learning entry discard | 1 | +| NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. | | | + +### **9.3.4 MAC bridge port configuration data** + +This ME models a port on a MAC bridge. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is linked to an instance of the MAC bridge service profile. Additional bridge port control capabilities are provided by implicitly linked instances of some or all of: + +- MAC bridge port filter table data; +- MAC bridge port filter pre-assign table; +- VLAN tagging filter data; +- Dot1 rate limiter. + +Real-time status of the bridge port is provided by implicitly linked instances of: + +- MAC bridge port designation data; +- MAC bridge port bridge table data; +- Multicast subscriber monitor. + +Bridge port PM collection is provided by implicitly linked instances of: + +- MAC bridge port PM history data; +- Ethernet frame PM history data upstream and downstream; +- Ethernet frame extended PM (preferred). + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Bridge ID pointer:** This attribute points to an instance of the MAC bridge service profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Port num:** This attribute is the bridge port number. It must be unique among all ports associated with a particular MAC bridge service profile. (R, W, set-by-create) (mandatory) (1 byte) + +**TP type:** This attribute identifies the type of TP associated with this MAC bridge port. Valid values are as follows. + +- 1 Physical path termination point Ethernet UNI +- 2 Interworking virtual circuit connection (VCC) termination point +- 3 IEEE 802.1p mapper service profile +- 4 IP host config data or IPv6 host config data +- 5 GEM interworking termination point +- 6 Multicast GEM interworking termination point +- 7 Physical path termination point xDSL UNI part 1 +- 8 Physical path termination point VDSL UNI +- 9 Ethernet flow termination point +- 10 Reserved +- 11 Virtual Ethernet interface point +- 12 Physical path termination point MoCA UNI +- 13 Ethernet in the first mile (EFM) bonding group + +(R, W, set-by-create) (mandatory) (1 byte) + +**TP pointer:** This attribute points to the TP associated with this MAC bridge port. The TP type attribute indicates the type of the TP; this attribute contains its instance identifier (ME ID). (R, W, set-by-create) (mandatory) (2 bytes) + +NOTE 1 – When the TP type is very high-speed digital subscriber line (VDSL) or xDSL, the two MSBs may be used to indicate a bearer channel. + +**Port priority:** This attribute denotes the priority of the port for use in (rapid) spanning tree algorithms. The range is 0..255. (R, W, set-by-create) (optional) (2 bytes) + +**Port path cost:** This attribute specifies the contribution of the port to the path cost towards the spanning tree root bridge. The range is 1..65535. (R, W, set-by-create) (mandatory) (2 bytes) + +**Port spanning tree ind:** The Boolean value true enables (R)STP LAN topology change detection at this port. The value false disables topology change detection. (R, W, set-by-create) (mandatory) (1 byte) + +**Deprecated 1:** This attribute is not used. If present, it should be ignored by both the ONU and the OLT, except as necessary to comply with OMCI message definitions. (R, W, set-by-create) (optional) (1 byte) + +**Deprecated 2:** This attribute is not used. If present, it should be ignored by both the ONU and the OLT, except as necessary to comply with OMCI message definitions. (R, W, set-by-create) (1 byte) (optional) + +**Port MAC address:** If the TP associated with this port has a MAC address, this attribute specifies it. (R) (optional) (6 bytes) + +**Outbound TD pointer:** This attribute points to a traffic descriptor that limits the traffic rate leaving the MAC bridge. (R, W) (optional) (2 byte) + +**Inbound TD pointer:** This attribute points to a traffic descriptor that limits the traffic rate entering the MAC bridge. (R, W) (optional) (2 byte) + +**MAC learning depth:** This attribute specifies the maximum number of MAC addresses to be learned by this MAC bridge port. The default value 0 specifies that there is no administratively imposed limit. (R, W, set-by-create) (optional) (1 byte) + +NOTE 2 – If this attribute is not zero, its value overrides the value set in the MAC learning depth attribute of the MAC bridge service profile. + +**LASP ID pointer:** This attribute points to an instance of the LASP ME. (R, W, set-by-create) (optional) (2 bytes) + +#### Actions + +Create, delete, get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|-------------------------------------------------------------------------------------------| +| 0 | Port blocking | This port has been blocked due to loop detection in accordance with [IEEE 802.1D] (Note). | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +NOTE – To determine the state of a MAC bridge port, the OLT can read the port state attribute of the MAC bridge port designation data. + +### 9.3.5 MAC bridge port designation data + +This ME records data associated with a bridge port. The ONU automatically creates or deletes an instance of this managed entity upon the creation or deletion of a MAC bridge port configuration data ME. + +#### *Relationships* + +An instance of this managed entity is associated with one MAC bridge port configuration data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data. (R) (mandatory) (2 bytes) + +**Designated bridge root cost port:** This attribute contains the designated root, designated cost, designated bridge and designated port, which are some of the outputs of the *read port parameters* operation defined in clause 14.8.2.1 of [IEEE 802.1D]: + +- identifier of the designated bridge for the port's segment (8 bytes); +- bridge identifier of the root transmitted by the designated bridge for the segment (8 bytes); +- port number of the designated port on the designated bridge considered to be part of this port's segment (4 bytes); +- path cost contribution of the designated port to this port's segment (4 bytes). + +Upon ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (24 bytes) + +**Port state:** This attribute provides status information on the port. Valid values include the following. + +- 0 Disabled +- 1 Listening +- 2 Learning +- 3 Forwarding +- 4 Blocking +- 5 Linkdown +- 6 (R)Stp\_off + +in accordance with [IEEE 802.1D]. (R) (mandatory) (1 byte) + +NOTE – The value *linkdown* is introduced to denote the port status when the Ethernet link state is down. This value distinguishes the case where Ethernet is physically down from the case where Ethernet is administratively locked, the latter being denoted by *disabled*. Be aware that this terminology violates the ITU-T convention that *disabled* is an operational state, not administrative. + +The value (R)stp\_off is introduced to denote the port status where the (rapid) spanning tree protocol has been disabled by setting the port spanning tree ind attribute of the MAC bridge port configuration data to false, and the Ethernet link state is up. This value distinguishes whether frame forwarding is under the control of (R)STP. + +#### *Actions* + +Get + +#### Notifications + +None. + +### 9.3.6 MAC bridge port filter table data + +This ME organizes data associated with a bridge port. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a MAC bridge port configuration data ME. + +NOTE – The OLT should disable the learning mode in the MAC bridge service profile before writing to the MAC filter table. + +#### Relationships + +An instance of this ME is associated with an instance of a MAC bridge port configuration data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +**MAC filter table:** This attribute lists MAC addresses associated with the bridge port, each with an allow/disallow forwarding indicator for traffic flowing out of the bridge port. Additionally, the forwarding action may be based on a MAC source or DA. In this way, upstream traffic is filtered on ANI-side bridge ports, and downstream traffic is filtered on UNI-side bridge ports. The setting of an entry with a forward action implies that all other addresses are filtered. Conversely, the setting of an entry with a filter action implies that all other addresses are forwarded. The behaviour is unspecified if forward and filter actions are mixed. + +Each entry contains: + +- the entry number, an index into this attribute list (1 byte); +- filter byte (1 byte); +- MAC address (6 bytes). + +The bits of the filter byte are assigned as follows. + +| Bit | Name | Setting | +|---------|----------------|-------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Filter/forward | 0: forward
1: filter | +| 2 | | 0: MAC DAs
1: MAC source addresses | +| 3..6 | Reserved | 0 | +| 7..8 | Add/remove | 10: Clear entire table (set operation)
00: Remove this entry (set operation)
01: Add this entry | + +Upon ME instantiation, the ONU sets this attribute to an empty table. + +(R, W) (Mandatory) (8*N* bytes, where *N* is the number of entries in the list) + +#### Actions + +Get, get next, set + +Set table (optional) + +#### Notifications + +None. + +### 9.3.7 MAC bridge port filter pre-assign table + +This ME provides an alternate approach to DA filtering from that supported through the MAC bridge port filter table data ME. This alternate approach is useful when all groups of addresses are stored beforehand in the ONU, and the MAC bridge port filter pre-assign table ME designates which groups are valid or invalid for filtering. On a circuit pack in which all groups of addresses are pre-assigned and stored locally, the ONU creates or deletes an instance of this ME automatically upon creation or deletion of a MAC bridge port configuration data ME. + +#### Relationships + +An instance of this ME is associated with an instance of a MAC bridge port configuration data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +The following 10 attributes have similar definitions. Each permits the OLT to specify whether MAC DAs or Ethertypes of the named type are forwarded (0) or filtered (1). In each case, the initial value of the attribute is 0. + +| No. | Protocol | MAC address | Ethertype | Standard | +|-----|-----------------------------------|----------------------------------------------------------------|-------------------|-------------------| +| 1 | IPv4 multicast | 01.00.5E.00.00.00 –
01.00.5E.7F.FF.FF | – | [b-IETF RFC 3232] | +| 2 | IPv6 multicast (Note) | 33.33.00.00.00.00 –
33.33.FF.FF.FF.FF | – | [IETF RFC 2464] | +| 3 | IPv4 broadcast | FF.FF.FF.FF.FF.FF | 0x0800 | [b-IETF RFC 3232] | +| 4 | RARP | FF.FF.FF.FF.FF.FF | 0x8035 | [b-IETF RFC 3232] | +| 5 | IPX | FF.FF.FF.FF.FF.FF | 0x8137 | [b-IETF RFC 3232] | +| | | 09.00.1B.FF.FF.FF,
09.00.4E.00.00.02 | – | | +| 6 | NetBEUI | 03.00.00.00.00.01 | – | | +| 7 | AppleTalk | FF.FF.FF.FF.FF.FF | 0x809B,
0x80F3 | [b-IETF RFC 3232] | +| | | 09.00.07.00.00.00 –
09.00.07.00.00.FC,
09.00.07.FF.FF.FF | – | | +| 8 | Bridge management information | 01.80.C2.00.00.00 –
01.80.C2.00.00.FF | – | [IEEE 802.1D] | +| 9 | Address resolution protocol (ARP) | FF.FF.FF.FF.FF.FF | 0x0806 | [b-IETF RFC 3232] | +| 10 | PPPoE broadcast | FF.FF.FF.FF.FF.FF | 0x8863 | [b-IETF RFC 2516] | + +NOTE – The specified MAC address range does not distinguish network control traffic from user traffic. The dot1 rate limiter may be a preferable way to limit the flow of IPv6 multicast traffic. + +| | | +|-------------------------------------------------|-----------------------------| +| IPv4 multicast filtering: | (R, W) (mandatory) (1 byte) | +| IPv6 multicast filtering: | (R, W) (mandatory) (1 byte) | +| IPv4 broadcast filtering: | (R, W) (mandatory) (1 byte) | +| RARP filtering: | (R, W) (mandatory) (1 byte) | +| IPX filtering: | (R, W) (mandatory) (1 byte) | +| NetBEUI filtering: | (R, W) (mandatory) (1 byte) | +| AppleTalk filtering: | (R, W) (mandatory) (1 byte) | +| Bridge management information filtering: | (R, W) (mandatory) (1 byte) | + +Note that some destination MAC addresses should never be forwarded, considering the following rules of [IEEE 802.1D]. + +- 1 Addresses from 01.80.C2.00.00.00 to 01.80.C2.00.00.0F are reserved. +- 2 Addresses from 01.80.C2.00.00.20 to 01.80.C2.00.00.2F are used for generic attribute registration protocol (GARP) applications. + +| | | +|-----------------------|-----------------------------| +| ARP filtering: | (R, W) (mandatory) (1 byte) | +|-----------------------|-----------------------------| + +| | | +|---------------------------------------------------------------------------|-----------------------------| +| Point-to-point protocol over Ethernet (PPPoE) broadcast filtering: | (R, W) (mandatory) (1 byte) | +|---------------------------------------------------------------------------|-----------------------------| + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.3.8 MAC bridge port bridge table data** + +This ME reports status data associated with a bridge port. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a MAC bridge port configuration data. + +#### *Relationships* + +An instance of this ME is associated with an instance of a MAC bridge port configuration data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +**Bridge table:** This attribute lists known MAC DAs, whether they are learned or statically assigned, whether packets that have them as DAs are filtered or forwarded, and their ages. Each entry contains: + +- Information (2 bytes); +- MAC address (6 bytes). + +The information bits are assigned as described as follows. + +| Bit | Name | Setting | +|------------|----------------|------------------------------------------------------------------------------| +| 1 (LSB) | Filter/forward | 0: forward
1: filter | +| 2 | Reserved | 0 | +| 3 | Dynamic/static | 0: this entry is statically assigned
1: this entry is dynamically learned | + +| | | | +|-------|----------|--------------------------| +| 4 | Reserved | 0 | +| 16..5 | Age | Age in seconds (1..4095) | + +Upon ME instantiation, this attribute is an empty list. (R) (mandatory) +(8 \* *M* bytes, where *M* is the number of entries in the list.) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.3.9 MAC bridge port performance monitoring history data** + +This ME collects PM data associated with a MAC bridge port. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of a MAC bridge port configuration data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Forwarded frame counter:** This attribute counts frames transmitted successfully on this port. (R) (mandatory) (4 bytes) + +**Delay exceeded discard counter:** This attribute counts frames discarded on this port because transmission was delayed. (R) (mandatory) (4 bytes) + +**Maximum transmission unit (MTU) exceeded discard counter:** This attribute counts frames discarded on this port because the MTU was exceeded. (R) (mandatory) (4 bytes) + +**Received frame counter:** This attribute counts frames received on this port. (R) (mandatory) (4 bytes) + +**Received and discarded counter:** This attribute counts frames received on this port that were discarded due to errors. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 1 | Delay exceeded discard | 1 | +| 2 | MTU exceeded discard | 2 | +| 4 | Received and discarded | 3 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.3.10 IEEE 802.1p mapper service profile + +This ME associates the priorities of IEEE 802.1p [IEEE 802.1D] priority tagged frames with specific connections. This ME directs upstream traffic to the designated GEM ports. Downstream traffic arriving on any of the IEEE 802.1p mapper's GEM ports is directed to the mapper's root TP. Other mechanisms exist to direct downstream traffic, specifically a direct pointer to a downstream queue from the GEM port network CTP. If such an alternative is used, it should be provisioned to be consistent with the flow model of the mapper. + +Instances of this ME are created and deleted by the OLT. + +#### Relationships + +At its root, an instance of this ME may be associated with zero or one instance of a PPTP UNI, MAC bridge port configuration data, or any type of IW TP ME that carries IEEE 802 traffic. Each of its eight branches is associated with zero or one GEM IW TP. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**TP pointer:** This attribute points to an instance of the associated TP. + +If the optional TP type attribute is not supported, the TP pointer indicates bridging mapping with the value 0xFFFF; the TP pointer may also point to a PPTP Ethernet UNI. + +The TP type value 0 also indicates bridging mapping, and the TP pointer should be set to 0xFFFF. + +In all other cases, the TP type is determined by the TP type attribute. + +(R, W, set-by-create) (mandatory) (2 bytes) + +Each of the following eight attributes points to the GEM IW TP associated with the stated P-bit value. The null pointer 0xFFFF specifies that frames with the associated priority are to be discarded. + +**Interwork TP pointer for P-bit priority 0:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 1:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 2:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 3:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 4:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 5:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 6:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Interwork TP pointer for P-bit priority 7:** (R, W, set-by-create) (mandatory) (2 bytes) + +**Unmarked frame option:** This attribute specifies how the ONU should handle untagged Ethernet frames received across the associated interface. Although it does not alter the frame in any way, the ONU routes the frame as if it were tagged with P bits (PCP field) according to the following code points. + +- 0 Derive implied PCP field from DSCP bits of received frame +- 1 Set implied PCP field to a fixed value specified by the default P-bit assumption attribute + +(R, W, set-by-create) (mandatory) (1 byte) + +Untagged downstream frames are passed through the mapper transparently. + +**DSCP to P-bit mapping:** This attribute is valid when the unmarked frame option attribute is set to 0. The DSCP to P-bit attribute can be considered a bit string sequence of 64 3 bit groupings. The 64 sequence entries represent the possible values of the 6 bit DSCP field. Each 3 bit grouping specifies the P-bit value to which the associated DSCP value should be mapped. The unmarked frame is then directed to the GEM IW TP indicated by the interwork TP pointer mappings. (R, W) (mandatory) (24 bytes) + +NOTE – If certain bits in the DSCP field are to be ignored in the mapping process, the attribute should be provisioned such that all possible values of those bits produce the same P-bit mapping. This can be applied to the case where instead of full DSCP, the operator wishes to adopt the priority mechanism based on IP precedence, which needs only the three MSBs of the DSCP field. + +**Default P-bit assumption:** This attribute is valid when the unmarked frame option attribute is set to 1. In its LSBs, the default P-bit assumption attribute contains the default PCP field to be assumed. The unmodified frame is then directed to the GEM IW TP indicated by the interwork TP pointer mappings. (R, W, set-by-create) (mandatory) (1 byte) + +**TP type:** This attribute identifies the type of TP associated with the mapper. + +- 0 Mapper used for bridging-mapping +- 1 Mapper directly associated with a PPTP Ethernet UNI +- 2 Mapper directly associated with an IP host config data or IPv6 host config data ME +- 3 Mapper directly associated with an Ethernet flow termination point +- 4 Mapper directly associated with a PPTP xDSL UNI +- 5 Reserved +- 6 Mapper directly associated with a PPTP MoCA UNI +- 7 Mapper directly associated with a virtual Ethernet interface point +- 8 Mapper directly associated with an IW VCC termination point +- 9 Mapper directly associated with an EFM bonding group + +(R, W, set-by-create) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.3.11 VLAN tagging filter data + +This ME organizes data associated with VLAN tagging. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with an instance of a MAC bridge port configuration data ME. By definition, tag filtering occurs closer to the MAC bridge than the tagging operation. Schematically, the ordering of the functions is as given in Figure 9.3.11-1: + +![Figure 9.3.11-1: Schematic diagram showing the ordering of functions for VLAN tagging. The sequence is: ANI -> Tag operation -> Tag filtering -> Bridging -> Tag filtering -> Tag operation -> UNI. A reference code G.988(12)_F9.3.11-1 is shown below the diagram.](f050e021720d7dbc135e918a25860117_img.jpg) + +``` + +graph LR + ANI[ANI] --> TO[Tag operation] + TO --> TF1[Tag filtering] + TF1 --> B[Bridging] + B --> TF2[Tag filtering] + TF2 --> TO2[Tag operation] + TO2 --> UNI[UNI] + +``` + +G.988(12)\_F9.3.11-1 + +Figure 9.3.11-1: Schematic diagram showing the ordering of functions for VLAN tagging. The sequence is: ANI -> Tag operation -> Tag filtering -> Bridging -> Tag filtering -> Tag operation -> UNI. A reference code G.988(12)\_F9.3.11-1 is shown below the diagram. + +Figure 9.3.11-1 + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data ME. (R, set-by-create) (mandatory) (2 bytes) + +**VLAN filter list:** This attribute is a list of provisioned tag control information (TCI) values for the bridge port. A TCI, comprising user priority, canonical format indicator (CFI) and virtual local area network identifier (VID), is represented by 2 bytes. This attribute supports up to 12 VLAN entries. The first $N$ are valid, where $N$ is given by the number of entries attribute. (R, W, set-by-create) (mandatory) (24 bytes) + +**Forward operation:** When a frame passes through the MAC bridge port, it is processed according to the operation specified by this attribute, in accordance with Table 9.3.11-1. Figure 9.3.11-3 illustrates the treatment of frames according to the provisioned action possibilities. Tagged and untagged frames are treated separately, but both in accordance with Figure 9.3.11-3. While all forwarding operations are plausible, only actions 0x10 and 0x12 are necessary to construct a VLAN mapper and an 802.1p mapper, respectively. (R, W, set-by-create) (mandatory) (1 byte) + +Table 9.3.11-1 – Forward operation attribute values + +| Forward operation | Type of received frame | | +|-------------------|------------------------------------------|----------------| +| | Tagged | Untagged | +| 0x00 | Bridging (a) (no investigation) | Bridging (a) | +| 0x01 | Discarding (c) | Bridging (a) | +| 0x02 | Bridging (a) (no investigation) | Discarding (c) | +| 0x03 | Action (h) (VID investigation) | Bridging (a) | +| 0x04 | Action (h) (VID investigation) | Discarding (c) | +| 0x05 | Action (g) (VID investigation) | Bridging (a) | +| 0x06 | Action (g) (VID investigation) | Discarding (c) | +| 0x07 | Action (h) (user priority investigation) | Bridging (a) | +| 0x08 | Action (h) (user priority investigation) | Discarding (c) | +| 0x09 | Action (g) (user priority investigation) | Bridging (a) | + +**Table 9.3.11-1 – Forward operation attribute values** + +| Forward operation | Type of received frame | | +|-------------------|------------------------------------------|----------------| +| | Tagged | Untagged | +| 0x0A | Action (g) (user priority investigation) | Discarding (c) | +| 0x0B | Action (h) (TCI investigation) | Bridging (a) | +| 0x0C | Action (h) (TCI investigation) | Discarding (c) | +| 0x0D | Action (g) (TCI investigation) | Bridging (a) | +| 0x0E | Action (g) (TCI investigation) | Discarding (c) | +| 0x0F | Action (h) (VID investigation) | Bridging (a) | +| 0x10 | Action (h) (VID investigation) | Discarding (c) | +| 0x11 | Action (h) (user priority investigation) | Bridging (a) | +| 0x12 | Action (h) (user priority investigation) | Discarding (c) | +| 0x13 | Action (h) (TCI investigation) | Bridging (a) | +| 0x14 | Action (h) (TCI investigation) | Discarding (c) | +| 0x15 | Bridging (a) (no investigation) | Discarding (c) | +| 0x16 | Action (j) (VID investigation) | Bridging (a) | +| 0x17 | Action (j) (VID investigation) | Discarding (c) | +| 0x18 | Action (j) (user priority investigation) | Bridging (a) | +| 0x19 | Action (j) (user priority investigation) | Discarding (c) | +| 0x1A | Action (j) (TCI investigation) | Bridging (a) | +| 0x1B | Action (j) (TCI investigation) | Discarding (c) | +| 0x1C | Action (h) (VID investigation) | Bridging (a) | +| 0x1D | Action (h) (VID investigation) | Discarding (c) | +| 0x1E | Action (h) (user priority investigation) | Bridging (a) | +| 0x1F | Action (h) (user priority investigation) | Discarding (c) | +| 0x20 | Action (h) (TCI investigation) | Bridging (a) | +| 0x21 | Action (h) (TCI investigation) | Discarding (c) | + +Table 9.3.11-1 contains duplicate entries due to simplification of the original set of actions. + +Table 9.3.11-1 and the actions listed are discussed in detail in the following. + +**Number of entries:** This attribute specifies the number of valid entries in the VLAN filter list. (R, W, set-by-create) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +#### Supplementary explanation + +This section explains the actions specified in the forward operation attribute. + +The format of an Ethernet frame for VLAN services is described in [IEEE 802.1Q] and [IEEE 802.1ad]. See Figure 9.3.11-2. + +![Figure 9.3.11-2: Format of an Ethernet frame for VLAN services. The diagram shows a hierarchical breakdown of an Ethernet frame. The top level shows DA, SA, Length/type, and MAC SDU. The Length/type field is expanded to show TPID and TCI. The TCI field is further expanded to show User priority (3 bits), CFI (1 bit), and VID (12 bits).](649426750a89fa0e5d7c1736d5cf72c6_img.jpg) + +G.988(12)\_F9.3.11-2 + +TCI: Tag control information + +Figure 9.3.11-2: Format of an Ethernet frame for VLAN services. The diagram shows a hierarchical breakdown of an Ethernet frame. The top level shows DA, SA, Length/type, and MAC SDU. The Length/type field is expanded to show TPID and TCI. The TCI field is further expanded to show User priority (3 bits), CFI (1 bit), and VID (12 bits). + +**Figure 9.3.11-2 – Format of an Ethernet frame for VLAN services** + +- a) Basic MAC bridge operation:** All frames are accepted into the MAC bridging entity. Egress frames are forwarded from this port if either a) the frame's MAC DA is listed in the MAC bridge port bridge table data for this port or b) the frame's DA does not appear in the MAC bridge port bridge table data for any port (flooding). The contents of the VLAN filter list attribute are not meaningful. See Figure 9.3.11-3. + +NOTE – Action (a) on a given port may imply egress flooding of a frame from other ports of the bridge. The possible VLAN tagging filter data MEs attached to the other ports override this action however, so the frame is only transmitted from another port if it also satisfies the forward operation attribute value established on that port. + +![Figure 9.3.11-3: Forwarding behaviour. This diagram illustrates the forwarding logic for five ports (P1 to P5) of an 802.1 bridging entity. A dashed box on the left lists the 'Functionality of (extended) VLAN tagging operation configuration data MEs, if any'. Arrows from this box point to specific conditions for each port. Port P1 (Action a) accepts all frames. Port P2 (Action c) discards all frames. Port P3 (Action g) discards frames where TCI does not match. Port P4 (Action h) accepts frames where TCI matches and (DA match or flooding). Port P5 (Action j) accepts frames where both TCI and DA match, with no flooding.](a969a3a831d0967b54efe1400846ed30_img.jpg) + +G.988(12)\_F9.3.11-3 + +Figure 9.3.11-3: Forwarding behaviour. This diagram illustrates the forwarding logic for five ports (P1 to P5) of an 802.1 bridging entity. A dashed box on the left lists the 'Functionality of (extended) VLAN tagging operation configuration data MEs, if any'. Arrows from this box point to specific conditions for each port. Port P1 (Action a) accepts all frames. Port P2 (Action c) discards all frames. Port P3 (Action g) discards frames where TCI does not match. Port P4 (Action h) accepts frames where TCI matches and (DA match or flooding). Port P5 (Action j) accepts frames where both TCI and DA match, with no flooding. + +**Figure 9.3.11-3 – Forwarding behaviour** + +Other possible actions are as follows: + +- c) **Unconditional discarding:** Frames in both directions are unconditionally discarded without an investigation of TCI or a MAC address. This action can be used to discard all tagged traffic or all untagged traffic at the port of attachment, depending on the forward operation attribute value. The contents of the VLAN filter list attribute are not meaningful. +- g) **Negative filtering by TCI:** All frames are admitted into the bridging entity. If the specified fields in the TCI of a candidate egress frame match any entry in the VLAN filter list, the frame is not forwarded by this port. Otherwise, the frame is forwarded based on the destination MAC address, according to action a). +- h) **Bidirectional positive filtering by TCI:** Both ingress and egress frames are filtered on investigation of the TCI fields. If and only if the specified fields in the TCI of a candidate ingress frame match an entry in the VLAN filter list, the frame is admitted into the bridge. If and only if the specified fields in the TCI of a candidate egress frame match an entry in the VLAN filter list, the frame is forwarded based on the destination MAC address, according to action a). +- j) **Positive filtering by TCI and DA:** All frames are admitted into the bridging entity. If the specified fields in the TCI of a candidate egress frame match any entry in the VLAN filter list, the frame is forwarded based on the destination MAC address. The frame is never flooded to this or other ports. If the specified TCI fields and DA do not both match, the frame is discarded. + +Action codes b), d), e) and f) are not used. + +### 9.3.12 VLAN tagging operation configuration data + +This ME organizes data associated with VLAN tagging. Instances of this ME are created and deleted by the OLT. + +NOTE 1 – The extended VLAN tagging operation configuration data of clause 9.3.13 is preferred for new implementations. + +#### *Relationships* + +Zero or one instance of this ME may exist for an instance of any ME that can terminate or modify an Ethernet stream. + +When this ME is associated with a UNI-side TP, it performs its upstream classification and tagging operations before offering the upstream frame to other filtering, bridging or switching functions. In the downstream direction, the defined inverse operation is the last operation performed on the frame before offering it to the UNI-side termination. + +When this ME is associated with an ANI-side TP, it performs its upstream classification and tagging operations as the last step before queueing for transmission to the OLT, after having received the upstream frame from other filtering, bridging or switching functions. In the downstream direction, the defined inverse operation is the first operation performed on the frame before offering it to possible filter, bridge or switch functions. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. When the optional association type attribute is 0 or undefined, this attribute's value is the same as the ID of the ME with which this VLAN tagging operation configuration data instance is associated, which may be either a PPTP Ethernet UNI or an IP host config data or an IPv6 host config data ME. Otherwise, the value of the ME ID is unconstrained except by the need to be unique. (R, set-by-create) (mandatory) (2 bytes) + +**Upstream VLAN tagging operation mode:** This attribute controls upstream VLAN tagging. + +Valid values are as follows. + +- 0 Upstream frame is sent as is, regardless of tag. +- 1 The upstream frame is tagged, whether or not the received frame was tagged. A tagged frame's TCI is overwritten with the upstream VLAN tag TCI value. An untagged frame is prepended with a tag whose values are taken from the upstream VLAN tag TCI value attribute. +- 2 A tag is prepended to the upstream frame, whether or not the received frame was tagged. If the received frame is tagged, a second tag (Q-in-Q) is added to the frame. If the received frame is not tagged, a tag is attached to the frame. The added tag is defined by the upstream VLAN tag TCI value attribute. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Upstream VLAN tag TCI value:** This attribute specifies the TCI for upstream VLAN tagging. It is used when the upstream VLAN tagging operation mode is 1 or 2. + +(R, W, set-by-create) (mandatory) (2 bytes) + +**Downstream VLAN tagging operation mode:** This attribute controls downstream VLAN tagging. Valid values are as follows. + +- 0 Downstream frame is sent as is, regardless of tag. +- 1 If the received frame is tagged, the outer tag is stripped. An untagged frame is forwarded unchanged. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Association type:** This attribute specifies the type of ME that is associated with this VLAN tagging operation configuration data ME. Values are assigned in accordance with the following list. + +- 0 (Default) Physical path termination point Ethernet UNI (for backward compatibility, may also be an IP host config data ME; they must not have the same ME ID). The associated ME instance is implicit; its identifier is the same as that of this VLAN tagging operation configuration data. +- 1 IP host config data or IPv6 host config data +- 2 IEEE 802.1p mapper service profile +- 3 MAC bridge port configuration data +- 4 Physical path termination point xDSL UNI +- 5 GEM IW termination point +- 6 Multicast GEM IW termination point +- 7 Physical path termination point MoCA UNI +- 8 Reserved +- 9 Ethernet flow termination point +- 10 Physical path termination point Ethernet UNI +- 11 Virtual Ethernet interface point +- 12 MPLS pseudowire termination point +- 13 EFM bonding group + +The associated ME instance is identified by the associated ME pointer. (R, W, set-by-create) (optional) (1 byte) + +**Associated ME pointer:** When the association type attribute is non-zero, this attribute points to the ME with which this VLAN tagging operation configuration data ME is associated. Otherwise, this attribute is undefined, and the association is implicit through the ME ID. (R, W, set-by-create) (optional) (2 bytes) + +NOTE 2 – Implicit association is retained for legacy compatibility. Explicit pointers are preferred for new implementations. + +NOTE 3 – When the association type is xDSL, the two MSBs may be used to indicate a bearer channel. + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.3.13 Extended VLAN tagging operation configuration data** + +This ME organizes data associated with VLAN classification and tagging operations. Regardless of its point of attachment, the specified tagging operations refer to the upstream direction. Instances of this ME are created and deleted by the OLT. + +Through separate attributes, this ME supports either a Received frame VLAN tagging operation table attribute in its backward compatible form, or an enhanced frame classification and processing capability. The OLT can determine whether the ONU supports the enhanced capability through the Enhanced mode attribute of the ONU3-G ME. + +#### *Relationships* + +Zero or one instance of this ME may exist for an instance of any ME that can terminate or modify an Ethernet stream. + +When this ME is associated with a UNI-side TP, it performs its upstream classification and tagging operations before offering the upstream frame to other filtering, bridging or switching functions. In the downstream direction, the defined inverse operation is the last operation performed on the frame before offering it to the UNI-side termination. + +When this ME is associated with an ANI-side TP, it performs its upstream classification and tagging operations as the last step before transmission to the OLT, after having received the upstream frame from other filtering, bridging or switching functions. In the downstream direction, the defined inverse operation is the first operation performed on the frame before offering it to possible filter, bridge or switch functions. + +#### *Attributes* + +**Managed entity ID:** This attribute provides a unique number for each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Association type:** This attribute identifies the type of the ME associated with this extended VLAN tagging ME. Values are assigned as follows. + +- 0 MAC bridge port configuration data +- 1 IEEE 802.1p mapper service profile +- 2 Physical path termination point Ethernet UNI +- 3 IP host config data or IPv6 host config data +- 4 Physical path termination point xDSL UNI +- 5 GEM IW termination point +- 6 Multicast GEM IW termination point +- 7 Physical path termination point MoCA UNI + +- 8 Reserved +- 9 Ethernet flow termination point +- 10 Virtual Ethernet interface point +- 11 MPLS pseudowire termination point +- 12 EFM bonding group + +(R, W, set-by-create) (mandatory) (1 byte) + +NOTE 1 – If a MAC bridge is configured, code points 1, 5, 6 and 11 are associated with the ANI side of the MAC bridge. Code point 0 is associated with the ANI or UNI side, depending on the location of the MAC bridge port. The other code points are associated with the UNI side. + +When the extended VLAN tagging ME is associated with the ANI side, it behaves as an upstream egress rule, and as a downstream ingress rule when the downstream mode attribute is equal to 0. When the extended VLAN tagging ME is associated with the UNI side, the extended VLAN tagging ME behaves as an upstream ingress rule, and as a downstream egress rule when the downstream mode attribute is equal to 0. + +**Received frame VLAN tagging operation table max size:** This attribute indicates the maximum number of entries that can be set in the received frame VLAN tagging operation table. (R) (mandatory) (2 bytes) + +**Input TPID:** This attribute gives the special TPID value for operations on the input (filtering) side of the table. Typical values include 0x88A8 and 0x9100. (R, W) (mandatory) (2 bytes) + +**Output TPID:** This attribute gives the special TPID value for operations on the output (tagging) side of the table. Typical values include 0x88A8 and 0x9100. (R, W) (mandatory) (2 bytes) + +**Downstream mode:** Regardless of its association, the rules of the received frame VLAN tagging operation table attribute pertain to upstream traffic. The downstream mode attribute defines the tagging action to be applied to downstream frames. + +The received frame VLAN tagging operation table installs defaults upstream rules. In the downstream direction, the upstream default rules with the default treatment do not apply. It should be noted that downstream frame treatment is defined by the downstream mode attribute and is not affected by the upstream default rules. + +The received frame VLAN tagging operation table can result in two types of rule mappings: + +- One to one mapping: A table contains one or more rules that result in unique mappings between the ingress and egress flows. +- Many to one mapping: A table contains more than one rule that results in the same ANI-side tag configuration. + +For one-to-one mappings, the inverse operation to apply in the downstream direction (in the case of bidirectional flows) is the inverse operation of the upstream rule. + +Many-to-one mappings are possible however, and these are treated as follows. + +- If an upstream many-to-one mapping results from multiple operation rules producing the same ANI-side tag configuration, then the first matching rule in the list defines the inverse operation. The meaning of match depends on the value of the downstream mode attribute. + +- If the many-to-one mapping results from "don't care" fields in the filter being replaced with provisioned fields in the ANI side tags, then the inverse is defined to set the corresponding fields on the ANI side to their lowest legal value. + +If the upstream rule merely copies (i.e., no explicit value is specified in the filter field) an inbound tag value to an outbound tag value, the comparison in the downstream direction applies to all tag values. This applies separately to the VID and P-bit fields. For example, with a downstream mode of 2 and an upstream rule that translates the VID while carrying forward the P-bit value, downstream frames that match the specified WAN-side VID will match any P-bit value and will translate the VID. + +- 0 The operation performed in the downstream direction is the inverse of that performed in the upstream direction. Which treatment and filter fields are used for downstream filtering and the handling of unmatched frames are left to the implementation of the ONU. +- 1 Regardless of the filter rules, no operation is performed in the downstream direction. All downstream frames are forwarded unmodified. +- 2 Filter on VID and P-bit value. On a match, perform the inverse operation on both the VID and P-bit value. If no match is found, forward the frame unmodified. +- 3 Filter on VID only. On a match, perform the inverse VID operation only; pass the P bits through. If no match is found, forward the frame unmodified. +- 4 Filter on P-bit only. On a match, perform the inverse P-bit operation only; pass the VID through. If no match is found, forward the frame unmodified. +- 5 Filter on VID and P-bit value. On a match, perform the inverse operation on both the VID and P-bit value. If no match is found, discard the frame. +- 6 Filter on VID. On a match, perform the inverse operation on the VID only; pass the P bits through. If no match is found, discard the frame. +- 7 Filter on P-bit only. On a match, perform the inverse P-bit operation only; pass the VID through. If no match is found, discard the frame. +- 8 Regardless of the filter rules, discard all downstream traffic. + +Please refer to Table 9.3.13-2 for example downstream mode use cases. + +All other values are reserved. (R, W) (mandatory) (1 byte) + +**Received frame VLAN tagging operation table:** This attribute is a table that filters and tags upstream frames. Each entry represents a tagging rule, comprising a filtering part (the first eight fields) and a treatment part (the last seven fields). Each incoming upstream packet is matched against each rule in list order. The first rule that matches the packet is selected as the active rule, and the packet is then treated according to that rule. + +There are three categories of rules: zero-tag, single-tag, and double-tag rules. Logically, these categories are separate, and apply to their respective incoming frame types. In other words, a single-tag rule should not apply to a double-tagged frame, even though the single-tag rule might match the outer tag of the double-tagged frame. + +Single-tag rules have a filter outer priority field = 15 (indicating no external tag), zero-tag rules have both filter priority fields = 15 (indicating no tags), and + +double-tag rules have both filter priority fields set to a value that differs from 15 (indicating two tags). + +Each tagging rule is based on a *remove* or an *add* operation, where up to two tags can be removed or added. A modify operation is applied by the combination of *remove* and *add*. + +By convention, when a single tag is added, the treatments use the inner tag data fields. This is true even for treatments where a single tag is added to a frame that already has a tag, i.e., added as a second tag. The outer tag data fields are used only when two tags are added by the same rule. + +The terms *inner* and *outer* only have meaning with respect to the tags that are being filtered or added. + +The first 8 bytes of each entry are guaranteed to be unique, and are used to identify table entries (*list order*, above, refers to a sort on the first 8 bytes). The OLT deletes a table entry by setting all of its last 8 bytes to 0xFF. + +When the table is created, the ONU should autonomously predefine three entries that list the default treatment (normal forwarding without filtering or modification) for untagged, single tagged, and double tagged frames. As an exception to the rule on ordered processing, these default rules are always considered as a last resort for frames that do not match any other rule. Best practice dictates that these entries not be deleted by the OLT; however, they can be modified to produce the desired default behaviour. + +It should be noted that downstream frame treatment is defined by the downstream mode attribute and is not affected by the upstream default rules. + +15, 4096, x, 15, 4096, x, 0, (0, 15, x, x, 15, x, x) – no tags + +15, 4096, x, 14, 4096, x, 0, (0, 15, x, x, 15, x, x) – 1 tag + +14, 4096, x, 14, 4096, x, 0, (0, 15, x, x, 15, x, x) – 2 tags + +NOTE 2 – x is a "don't care" field and should be set to zero. + +See Figure 9.3.13-1. + +(R, W) (mandatory) (16N bytes, where N is the number of VLAN tagging rules) + +![](44975a59174a634c7c5f49a9fb8eae71_img.jpg) + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|--------|---------------------------|----|------------------------|----|----|----|----|--------------------------|--------------------------|---------------------|---------------------|----|----------------------|----|-----------------------------|----|----|----|----|-------------------------|-------------------------|----|---|---|---|---|---|---|---|---|---|---| +| | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +| Word 1 | Filter outer priority | | Filter outer VID | | | | | | | | | | Filter outer TPID/DE | | Pad (reserved) 12 bits | | | | | | | | | | | | | | | | | | +| Word 2 | Filter inner priority | | Filter inner VID | | | | | | | | | | Filter inner TPID/DE | | Filter on extended criteria | | | | | | Filter Ethertype | | | | | | | | | | | | +| Word 3 | Treatment, tags to remove | | Pad (reserved) 10 bits | | | | | | Treatment outer priority | | Treatment outer VID | | | | | | | | | | Treatment outer TPID/DE | | | | | | | | | | | | +| Word 4 | Pad (reserved) 12 bits | | | | | | | Treatment inner priority | | Treatment inner VID | | | | | | | | | | Treatment inner TPID/DE | | | | | | | | | | | | | + +G.988(17)-Amd.2(19)\_F9.3.13-1 + +Figure 9.3.13-1 – Received frame VLAN tagging operation layout + +**Filter outer priority:** (4 bits) Defines the outer VLAN priority filtering operation. The following values are supported: + +- 0..7 Filter received frames on this outer priority (P bit) value. +- 8 Do not filter on outer priority. +- 14 This is the default filter when no other two-tag rule applies. +- 15 This entry is not a double-tag rule; ignore all other outer tag filter fields. + +Other values: reserved. + +**Filter outer VID:** (13 bits) Defines the outer VLAN VID filtering operation. The following values are supported: + +- 0..4094 Filter received frames on this outer VID value. +- 4096 Do not filter on the outer VID. + +Other values: reserved. + +**Filter outer TPID/DEI:** (3 bits) Defines the outer VLAN TPID/DEI filtering operation. The following values are supported: + +- 000 Do not filter on outer TPID field. +- 100 Outer TPID = 0x8100. Filter on frames with the outer TPID set to 0x8100. +- 101 Outer TPID = input TPID attribute value, don't care about DEI bit. Filter on frames with the outer TPID set to match the Extended VLAN tagging operation configuration data Input TPID attribute value and ignore the DEI bit. +- 110 Outer TPID = input TPID, DEI = 0. Filter on frames with the outer TPID set to match the Extended VLAN tagging operation configuration data Input TPID attribute value and DEI set to the value 0. +- 111 Outer TPID = input TPID, DEI = 1. Filter on frames with the outer TPID set to match the Extended VLAN tagging operation configuration data Input TPID attribute value and DEI set to the value 1 + +Padding: (12 bits) + +**Filter inner priority:** (4 bits) Defines the inner VLAN priority filtering operation. The following values are supported: + +- 0..7 Filter received frames on this inner priority value. +- 8 Do not filter on inner priority. +- 14 This is the default filter when no other one-tag rule applies. +- 15 This entry is a no-tag rule; ignore all other VLAN tag filter fields. + +Other values: reserved. + +**Filter inner VID:** (13 bits) Defines the inner VLAN VID filtering operation. The following values are supported: + +- 0..4094 Filter received frames on this inner VID value. +- 4096 Do not filter on the inner VID. + +Other values: reserved. + +**Filter inner TPID/DEI:** (3 bits) Defines the inner VLAN TPID/DEI filtering operation. The following values are supported: + +- 000 Do not filter on inner TPID field. +- 100 Inner TPID = 0x8100. Filter on frames with the inner TPID set to 0x8100. +- 101 Inner TPID = input TPID attribute value, don't care about DEI bit. Filter on frames with the inner TPID set to match the Extended VLAN tagging operation configuration data Input TPID attribute value and ignore the DEI bit. +- 110 Inner TPID = input TPID, DEI = 0. Filter on frames with the inner TPID set to match the Extended VLAN tagging operation configuration data Input TPID attribute value and DEI set to the value 0. +- 111 Inner TPID = input TPID, DEI = 1. Filter on frames with the inner TPID set to match the Extended VLAN tagging operation configuration data Input TPID attribute value and DEI set to the value 1. + +Padding: (8 bits) + +**Filter Ethertype:** (4 bits) the Ethertype value on which to filter received frames, as follows. + +NOTE 3 – This filter is recommended for use on untagged frames or frames with priority tags only. + +- 0 Do not filter on Ethertype. +- 1 Ethertype = 0x0800 (filter IPoE frames) +- 2 Ethertype = 0x8863 or 0x8864 (filter PPPoE frames) +- 3 Ethertype = 0x0806 (filter ARP frames) +- 4 Ethertype = 0x86DD (filter IPv6 IpoE frames) +- 5 Ethertype = 0x888E (filter EAPOL frames) + +Other values: reserved. + +**Filter on extended criteria:** (8 bits) filter on key upper level protocols: + +- 0 Do not filter on extended criteria +- 1 DHCPv4 – frames matching the well-known DHCPv4 UDP ports (67, 68) will be filtered by this criteria code point. +- 2 DHCPv6 – frames matching the well-known DHCPv6 UDP ports (546, 547) will be filtered by this criteria code point. + +NOTE 4 – This filter is recommended for use on untagged frames or priority framed tags only. + +**Treatment tags to remove:** (2 bits) Defines the tag treatment. The following values are supported: + +- 0..2 Remove 0, 1 or 2 tags, respectively. If one tag is specified, then the outer tag is stripped from double-tagged frames. +- 3 Discard the frame. No symmetric downstream operation exists; i.e., this rule is ignored in the downstream direction. + +Padding: (10 bits) + +**Treatment outer priority:** (4 bits): Defines the outer VLAN priority treatment. The following values are supported: + +- 0..7 Add an outer tag, and insert this value as the priority in the outer VLAN tag. + - 8 Add an outer tag, and copy the outer priority from the inner priority of the received frame. + - 9 Add an outer tag, and copy the outer priority from the outer priority of the received frame. + - 10 Add an outer tag, and derive P bits from the DSCP field of the incoming frame according to the Extended VLAN tagging operation configuration data ME DSCP to P-bit mapping attribute. + - 15 Do not add an outer tag. +- Other values: reserved. + +**Treatment outer VID:** (13 bits). Defines the outer VID treatment. The following values are supported: + +- 0..4094 Use this value as the VID in the outer VLAN tag. + - 4096 Copy the outer VID from the inner VID of the received frame. + - 4097 Copy the outer VID from the outer VID of the received frame. +- Other values: reserved. + +**Treatment outer TPID/DEI:** (3 bits). Defines the outer VLAN TPID/DEI treatment. The following values are supported: + +- 000 Copy TPID (and DEI, if present) from the inner tag of the received frame. +- 001 Copy TPID (and DEI, if present) from the outer tag of the received frame. +- 010 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and copy DEI bit from the inner tag of the received frame +- 011 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and copy DEI from the outer tag of the received frame +- 100 Set TPID = 0x8100 +- 101 Reserved +- 110 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and set DEI = 0 +- 111 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and set DEI = 1 + +Padding: (12 bits) + +**Treatment inner priority:** (4 bits). Defines the inner VLAN priority treatment. The following values are supported: + +- 0..7 Add an inner tag, and insert this value as the priority to insert in the inner VLAN tag. +- 8 Add an inner tag, and copy the inner priority from the inner priority of the received frame. +- 9 Add an inner tag, and copy the inner priority from the outer priority of the received frame. +- 10 Add an inner tag, and derive P bits from the DSCP field of the incoming frame according to the Extended VLAN tagging operation configuration data ME DSCP to P-bit mapping attribute. +- 15 Do not add an inner tag. + +Other values: reserved. + +**Treatment inner VID:** (13 bits): Defines the inner VLAN VID treatment. The following values are supported: + +- 0..4094 Use this value as the VID in the inner VLAN tag. +- 4096 Copy the inner VID from the inner VID of the received frame. +- 4097 Copy the inner VID from the outer VID of the received frame. + +Other values: reserved. + +**Treatment inner TPID/DEI:** (3 bits). Defines the inner VLAN TPID/DEI treatment. The following values are supported: + +- 000 Copy TPID (and DEI, if present) from the inner tag of the received frame. +- 001 Copy TPID (and DEI, if present) from the outer tag of the received frame. +- 010 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and copy the DEI bit from the inner tag of the received frame. +- 011 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and, copy the DEI from the outer tag of the received frame. +- 100 Set TPID = 0x8100 +- 101 Reserved +- 110 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and set DEI = 0 +- 111 Set TPID = output TPID attribute value of the Extended VLAN tagging operation configuration data ME and set DEI = 1 + +**Associated ME pointer:** This attribute points to the ME with which this extended VLAN tagging operation configuration data ME is associated. (R, W, set-by-create) (mandatory) (2 bytes) + +NOTE 5 – When the association type is xDSL, the two MSBs may be used to indicate a bearer channel. + +**DSCP to P-bit mapping:** This attribute specifies mapping from DSCP to P bits. The attribute can be considered a bit string sequence of 64 3 bit groups. The 64 sequence entries represent the possible values of the 6 bit DSCP field. Each 3 bit group specifies the P-bit value to which the associated DSCP value should be mapped. (R, W) (optional) (24 bytes) + +NOTE 6 – If certain bits in the DSCP field are to be ignored in the mapping process, the attribute should be provisioned such that all possible values of those bits produce the same P-bit mapping. This can be applied to the case where instead of full DSCP, the operator wishes to adopt the priority mechanism based on IP precedence, which needs only the three MSBs of the DSCP field. + +**Enhanced mode:** The Boolean value true specifies that the Enhanced received frame classification and processing table is used, and the Received frame VLAN tagging operation table is ignored. The value false indicates the Enhanced received frame classification and processing table is not used. It is strongly recommended that the OLT uses the same value for all Extended VLAN tagging operation configuration data instances created on an ONU. (R, Set-by-create) (optional) (1 byte) + +**Enhanced received frame classification and processing table:** This attribute is a table that provides enhanced capability for frame classification and processing. It extends the Received frame VLAN tagging operation table attribute with a set control field, a row key and direction. Each incoming packet is matched against each rule in row key order (smaller value row key has higher precedence) and direction. The first rule that matches the packet is selected as the active rule, and the packet is then treated according to that rule. + +When the table is empty, the ONU discards all received frames. The OLT may choose to create three entries that list the default treatment (normal forwarding without filtering or modification) for untagged, single tagged, and double tagged frames, with the direction field set to 0. + +NOTE 7 – Where no change is noted, the definitions in the Received frame VLAN tagging operation table attribute remain applicable. + +(R, W) (optional) (28N bytes, where N is the number of entries in the table). + +![Diagram showing the layout of the Enhanced received frame classification and processing table. It consists of 7 words (Word 1 to Word 7) and 32 bits (0 to 31). Word 1 contains Set ctrl (2 bits), Dir (1 bit), Pad (reserved) (12 bits), and Row key (17 bits). Word 2 contains Filter outer priority (2 bits), Filter outer VID (12 bits), Filter outer TPID/DE (2 bits), and Pad (reserved) (12 bits). Word 3 contains Filter inner priority (2 bits), Filter inner VID (12 bits), Filter inner TPID/DE (2 bits), Filter on extended criteria (2 bits), and Filter Ethertype (2 bits). Word 4 contains Treatment, tags to remove (1 bit), Pad (reserved) (10 bits), Treatment outer priority (2 bits), Treatment outer VID (12 bits), and Treatment outer TPID/DE (2 bits). Word 5 contains Pad (reserved) (12 bits), Treatment inner priority (2 bits), Treatment inner VID (12 bits), and Treatment inner TPID/DE (2 bits). Word 6 and Word 7 are Reserved.](d871d4c53f2d5c336a44d9e2e28fe792_img.jpg) + +| | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +|--------|---------------------------|---------------------------|------------------|---------------------------|----|----|----|----|----|----|----|--------------------------|--------------------------|---------------------|----------------------|---------|-----------------------------|----|----|----|----|----|------------------|---|---|-------------------------|-------------------------|---|---|---|---|---| +| Word 1 | Set ctrl | | Dir | Pad (reserved)
12 bits | | | | | | | | | | | | Row key | | | | | | | | | | | | | | | | | +| Word 2 | Filter outer priority | | Filter outer VID | | | | | | | | | | | | Filter outer TPID/DE | | Pad (reserved)
12 bits | | | | | | | | | | | | | | | | +| Word 3 | Filter inner priority | | Filter inner VID | | | | | | | | | | | | Filter inner TPID/DE | | Filter on extended criteria | | | | | | Filter Ethertype | | | | | | | | | | +| Word 4 | Treatment, tags to remove | Pad (reserved)
10 bits | | | | | | | | | | Treatment outer priority | | Treatment outer VID | | | | | | | | | | | | Treatment outer TPID/DE | | | | | | | +| Word 5 | Pad (reserved)
12 bits | | | | | | | | | | | | Treatment inner priority | | Treatment inner VID | | | | | | | | | | | | Treatment inner TPID/DE | | | | | | +| Word 6 | Reserved | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| Word 7 | Reserved | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +Diagram showing the layout of the Enhanced received frame classification and processing table. It consists of 7 words (Word 1 to Word 7) and 32 bits (0 to 31). Word 1 contains Set ctrl (2 bits), Dir (1 bit), Pad (reserved) (12 bits), and Row key (17 bits). Word 2 contains Filter outer priority (2 bits), Filter outer VID (12 bits), Filter outer TPID/DE (2 bits), and Pad (reserved) (12 bits). Word 3 contains Filter inner priority (2 bits), Filter inner VID (12 bits), Filter inner TPID/DE (2 bits), Filter on extended criteria (2 bits), and Filter Ethertype (2 bits). Word 4 contains Treatment, tags to remove (1 bit), Pad (reserved) (10 bits), Treatment outer priority (2 bits), Treatment outer VID (12 bits), and Treatment outer TPID/DE (2 bits). Word 5 contains Pad (reserved) (12 bits), Treatment inner priority (2 bits), Treatment inner VID (12 bits), and Treatment inner TPID/DE (2 bits). Word 6 and Word 7 are Reserved. + +G.988(17)-Amd.3(20)\_F9.3.13-2 + +**Figure 9.3.13-2 – Enhanced received frame classification and processing layout** + +##### **Set ctrl: (2 bits)** + +This field determines the meaning of a set operation. These bits are returned as 00 during get next operations. + +- 1 Write this entry into the table. Overwrite any existing entry with the same row key. +- 2 Delete this entry from the table. The remaining fields are not meaningful. + +NOTE 8 – Unlike the delete operation in the Received frame VLAN tagging operation table, the OLT does not need to set all eight bytes in Word 4 and Word 5 to 0xFF. + +- 3 Clear all entries from the table. The remaining fields are not meaningful. + +Other values: reserved. + +##### **Dir: (2 bits)** + +This field determines the direction of the classification and processing rule. + +- 0 This is an upstream rule. In the downstream direction, the inverse classification and operation is defined based on the downstream mode code point. All downstream mode codepoints are considered valid to be used when dir=0 is used (including downstream mode 8). +- 1 This is an upstream-only rule. This rule is ignored in the downstream direction. +- 2 This is a downstream-only rule. This rule is ignored in the upstream direction. + +Other values: reserved. + +##### **Row key: (16 bits)** + +The row key distinguishes rows in the table. It is the responsibility of the OLT to assign and track row keys and content, and to ensure the classification rules are not duplicated and in the correct ordering. + +For Filter outer priority, Filter outer VID, Filter outer TPID/DEI, Filter inner priority, Filter inner VID, Filter inner TPID/DEI, Filter on Extended Criteria, Filter Ethertype, Treatment outer priority, Treatment outer VID, Treatment outer TPID/DEI, Treatment inner priority, Treatment inner VID, and Treatment inner TPID/DEI values please refer to Received frame VLAN tagging operation table in this ME. + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +Table 9.3.13-1 illustrates the rule structure for many of the common VLAN tagging operations. For brevity, Table 9.3.13-1 omits columns for TPID/DEI, where the operator customizes the behaviour to a specific service model. + +The following abbreviations are used in the "action type" column: + +F Refers to an Ethernet Frame II frame + +→ Refers to the expected action in the upstream direction. For example F → X-F is an example where an 802.1q header is added with VID value of X. + +P Refers to the P-bit associated with VID Tag X or Y. + +X, Y Refer to VID Tag X or Y + +S Refers to S-tag or outermost tag as defined in IEEE 802.1ad and having a typical Ethertype value of 0x88a8. + +C Refer to a C-tag or innermost VLAN tag as defined in IEEE 802.1ad and having a typical Ethertype value of 0x8100. Typically, a service VLAN (S-VLAN) delivers a single service to all subscribers, while a customer VLAN (C-VLAN) delivers multiple services to a single subscriber. + +These are often combined by using a single S-VLAN to carry specific service traffic to all subscribers, by using dedicated C-VLANs to carry all service traffic to each subscriber. + +**Table 9.3.13-1 – Common VLAN tagging operations** + +| Action type | Filter | | | | | Treatment | | | | | +|--------------------------------------------------------------|----------|------|----------|------|-----------|----------------|----------|-----|----------|-----| +| | Outer | | Inner | | | Tags to remove | Outer | | Inner | | +| | Priority | VID | Priority | VID | Ethertype | | Priority | VID | Priority | VID | +| Upstream frame type = Untagged frames | | | | | | | | | | | +| Insert 1 tag (X):
F → X-F | 15 | 4096 | 15 | 4096 | 0 | 0 | 15 | N/A | Px | X | +| Default case, do nothing | 15 | 4096 | 15 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | +| Insert 2 tags (X,Y):
F → Y-X-F | 15 | 4096 | 15 | 4096 | 0 | 0 | Py | Y | Px | X | +| Upstream frame type = Single tagged frames | | | | | | | | | | | +| Insert 1 tag (X):
C-F → X-C-F | 15 | 4096 | 8 | C | 0 | 0 | 15 | N/A | Px | X | +| Insert 1 tag (X), copy priority:
C-F → X-C-F | 15 | 4096 | 8 | C | 0 | 0 | 15 | N/A | 8 | X | +| Insert 2 tags (X,Y):
C-F → Y-X-C-F | 15 | 4096 | 8 | C | 0 | 0 | Py | Y | Px | X | +| Modify tag:
C-F → X-F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | Px | X | +| Modify tag, keep original priority:
C-F → X-F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | 8 | X | +| Modify and insert tag:
C-F → Y-X-F | 15 | 4096 | 8 | C | 0 | 1 | Py | Y | Px | X | +| Remove tag:
C-F → F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | 15 | N/A | +| Insert two tags:
C-F → Y-X-C-F | 15 | 4096 | 8 | C | 0 | 0 | Py | Y | Px | X | +| Default case, do nothing | 15 | 4096 | 14 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | +| Upstream frame type = Double tagged frames | | | | | | | | | | | +| Insert 1 tag (X):
S-C-F → X-S-C-F | 8 | S | 8 | C | 0 | 0 | 15 | N/A | Px | X | +| Insert 1 tag (X), copy external priority:
S-C-F → X-S-C-F | 8 | S | 8 | C | 0 | 0 | 15 | N/A | 9 | X | + +**Table 9.3.13-1 – Common VLAN tagging operations** + +| Action type | Filter | | | | | Treatment | | | | | +|-----------------------------------------------------------------------------------|----------|------|----------|------|-----------|----------------|----------|------|----------|------| +| | Outer | | Inner | | | Tags to remove | Outer | | Inner | | +| | Priority | VID | Priority | VID | Ethertype | | Priority | VID | Priority | VID | +| Insert 2 tags (X,Y):
S-C-F → Y-X-S-C-F | 8 | S | 8 | C | 0 | 0 | Py | Y | Px | X | +| Insert 2 tags (X,Y), copy
external and internal priority:
S-C-F → Y-X-S-C-F | 8 | S | 8 | C | 0 | 0 | 9 | Y | 8 | X | +| Modify outer tag:
S-C-F → X-C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | Px | X | +| Modify outer tag,
keep original priority:
S-C-F → X-C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | 9 | X | +| Modify both tags:
S-C-F → Y-X-F | 8 | S | 8 | C | 0 | 2 | Py | Y | Px | X | +| Modify both tags,
keep original priorities:
S-C-F → Y-X-F | 8 | S | 8 | C | 0 | 2 | 9 | Y | 8 | X | +| Swap both tags:
S-C-F → C-S-F | 8 | S | 8 | C | 0 | 2 | 8 | 4096 | 9 | 4097 | +| Remove outer tag:
S-C-F → C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | 15 | N/A | +| Remove both tags:
S-C-F → F | 8 | S | 8 | C | 0 | 2 | 15 | N/A | 15 | N/A | +| Default case, do nothing
S-C-F → S-C-F | 14 | 4096 | 14 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | + +Table 9.3.13-2 illustrates the downstream behaviour for common deployment scenarios based on the downstream mode code point and the upstream rule. For brevity, Table 9.3.13-2 omits a column for P-bit only, but the downstream action can be inferred from the VID only column. + +If the inner packet tag information is not available (i.e., in cases with more than one VID or VID+PBIT value in "VID-only" and "Both P and VID," such as "X and C" and "Px and Py and X and Y"), only outer tag information is used in the downstream filtering rule. + +Table 9.3.13-2 uses the same abbreviations used in Table 9.3.13-1. + +**Table 9.3.13-2 – Downstream mode use case examples** + +| Upstream action type | Filter | | | | | Treatment | | | | | Downstream action | | | | Notes | | +|---------------------------------------------------|----------|------|----------|------|-----------|----------------|----------|-----|----------|-----|-------------------------------------|---------------|-----------------------------|-----------------------------------------------------------|-------|--| +| | Outer | | Inner | | | Tags to remove | Outer | | Inner | | Consider only downstream frame type | VID only | Both P and VID | Action | | | +| | Priority | VID | Priority | VID | Ethertype | | Priority | VID | Priority | VID | | | | | | | +| Upstream frame type= Untagged frames | | | | | | | | | | | | | | | | | +| Insert 1tag (X): F → X-F | 15 | 4096 | 15 | 4096 | 0 | 0 | 15 | N/A | Px | X | Single tagged | X | Px and X | Strip tag | | | +| Default case, do nothing | 15 | 4096 | 15 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | Untagged | – | – | Pass unmodified | | | +| Insert 2 tags (X,Y): F → Y-X-F | 15 | 4096 | 15 | 4096 | 0 | 0 | Py | Y | Px | X | Double tagged | X and Y | Px and Py and X and Y | Strip two tags | | | +| Upstream frame type = Single tagged frames | | | | | | | | | | | | | | | | | +| Insert 1 tag (X): C-F → X-C-F | 15 | 4096 | 8 | C | 0 | 0 | 15 | N/A | Px | X | Double tagged | X and C | X and Px and C | Strip outer tag (X) | | | +| Insert 1 tag (X), copy priority: C-F → X-C-F | 15 | 4096 | 8 | C | 0 | 0 | 15 | N/A | 8 | X | Double tagged | X and C | X and C | Strip outer tag (X), copy priority onto remaining tag (C) | | | +| Insert 2 tags (X,Y): C-F → Y-X-C-F | 15 | 4096 | 8 | C | 0 | 0 | Py | Y | Px | X | Triple tagged | X and Y and C | Px and Py and X and Y and C | Strip two outer tags (X, Y) | | | + +Table 9.3.13-2 – Downstream mode use case examples + +| Upstream action type | Filter | | | | | Treatment | | | | | Downstream action | | | | | +|--------------------------------------------------|----------|------|----------|------|------------|----------------|----------|-----|----------|-----|-------------------------------------|---------------|-----------------------------|-----------------------------|------------------------------------------------------------------------------------------------------------| +| | Outer | | Inner | | | Tags to remove | Outer | | Inner | | Consider only downstream frame type | VID only | Both P and VID | Action | Notes | +| | Priority | VID | Priority | VID | Etheretype | | Priority | VID | Priority | VID | | | | | | +| Modify tag:
C-F → X-F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | Px | X | Single tagged | X | Px and X | Replace X with C, retain Px | Use treatment specified in downstream mode definition for the remaining P-bit set {for C VID} if ambiguous | +| Modify tag, keep original priority:
C-F → X-F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | 8 | X | Single tagged | X | Px and X | Replace X with C, retain Px | Use treatment specified in downstream mode definition for the remaining P-bit set {for C VID} if ambiguous | +| Modify and insert tag:
C-F → Y-X-F | 15 | 4096 | 8 | C | 0 | 1 | Py | Y | Px | X | Double tagged | X and Y | X and Px, Y and Py | Strip outer tag (Y) | | +| Remove tag:
C-F → F | 15 | 4096 | 8 | C | 0 | 1 | 15 | N/A | 15 | N/A | Untagged | - | - | Add tag, VID = C, P = 0 | | +| Insert two tags:
C-F → Y-X-C-F | 15 | 4096 | 8 | C | 0 | 0 | Py | Y | Px | X | Triple tagged | X and Y and C | Px and Py and X and Y and C | Strip two outer tags (Y, X) | | +| Default case, do nothing | 15 | 4096 | 14 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | Single tagged | – | – | Pass unmodified | | +| Upstream frame type = Double tagged frames | | | | | | | | | | | | | | | | + +Table 9.3.13-2 – Downstream mode use case examples + +| Upstream action type | Filter | | | | | Treatment | | | | | Downstream action | | | | Notes | | +|--------------------------------------------------------------------------------|----------|-----|----------|-----|-----------|----------------|----------|-----|----------|-----|-------------------------------------|---------------------|-----------------------------------|--------------------------------------------------------------------|-------|--| +| | Outer | | Inner | | | Tags to remove | Outer | | Inner | | Consider only downstream frame type | VID only | Both P and VID | Action | | | +| | Priority | VID | Priority | VID | Ethertype | | Priority | VID | Priority | VID | | | | | | | +| Insert 1 tag (X):
S-C-F → X-S-C-F | 8 | S | 8 | C | 0 | 0 | 15 | N/A | Px | X | Triple tagged | X and S and C | X and Px and S and C | Strip outer tag (X) | | | +| Insert 1 tag (X), copy outer priority:
S-C-F → X-S-C-F | 8 | S | 8 | C | 0 | 0 | 15 | N/A | 9 | X | Triple tagged | X and S and C | X and S and C | Strip outer tag(X) copy priority (Px) onto resulting outer tag (S) | | | +| Insert 2 tags (X,Y):
S-C-F → Y-X-S-C-F | 8 | S | 8 | C | 0 | 0 | Py | Y | Px | X | Quad tagged | X and Y and S and C | Px and Py and X and Y and S and C | Strip two outer tags (Y, X) | | | +| Insert 2 tags (X,Y), copy external and internal priority:
S-C-F → Y-X-S-C-F | 8 | S | 8 | C | 0 | 0 | 9 | Y | 8 | X | Quad tagged | X and Y and S and C | X and Y and S and C | Strip two outer tags (Y, X), copy Px, Py onto remaining tags (S,C) | | | +| Modify external tag:
S-C-F → X-C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | Px | X | ≥ 2 tags | X and C | Px and X and C | Replace X with S in outer tag | | | +| Modify external tag, keep original priority:
S-C-F → X-C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | 9 | X | ≥ 2 tags | X and C | X and C | Modify outer tag VID = S, retain priority | | | + +**Table 9.3.13-2 – Downstream mode use case examples** + +| Upstream action type | Filter | | | | | Treatment | | | | | Downstream action | | | | | +|--------------------------------------------------------------|----------|------|----------|------|-----------|----------------|----------|------|----------|------|-------------------------------------|----------|-----------------------|----------------------------------------|---------------------------------------------------------------------------------------------------------| +| | Outer | | Inner | | | Tags to remove | Outer | | Inner | | Consider only downstream frame type | VID only | Both P and VID | Action | Notes | +| | Priority | VID | Priority | VID | Ethertype | | Priority | VID | Priority | VID | | | | | | +| Modify both tags:
S-C-F → Y-X-F | 8 | S | 8 | C | 0 | 2 | Py | Y | Px | X | ≥ 2 tags | X and Y | Px and Py and X and Y | Modify tags with S, C, retain priority | Use treatment specified in downstream mode definition for the remaining P-bit sets {S} {C} if ambiguous | +| Modify both tags, keep original priorities:
S-C-F → Y-X-F | 8 | S | 8 | C | 0 | 2 | 9 | Y | 8 | X | ≥ 2 tags | X and Y | X and Y | Modify tags with S, C, retain priority | Use treatment specified in downstream mode definition for the remaining P-bit sets {S} {C} if ambiguous | +| Swap both tags:
S-C-F → C-S-F | 8 | S | 8 | C | 0 | 2 | 8 | 4096 | 9 | 4097 | ≥ 2 tags | S and C | S and C | Swap tags (C, S) | | +| Remove outer tag:
S-C-F → C-F | 8 | S | 8 | C | 0 | 1 | 15 | N/A | 15 | N/A | Single tagged | C | C | Add Tag S, p-bit=0 | | +| Remove both tags:
S-C-F → F | 8 | S | 8 | C | 0 | 2 | 15 | N/A | 15 | N/A | untagged | – | – | Add Tags S, C, p-bit=0 | | +| Default case, do nothing
S-C-F → S-C-F | 14 | 4096 | 14 | 4096 | 0 | 0 | 15 | N/A | 15 | N/A | ≥ 2 tags | – | – | Pass unmodified | | + +### 9.3.14 Dot1X port extension package + +An instance of this ME represents a set of attributes that control a port's IEEE 802.1X operation. It is created and deleted autonomously by the ONU upon the creation or deletion of a PPTP that supports [IEEE 802.1X] authentication of customer premises equipment (CPE). + +#### *Relationships* + +An instance of this ME is associated with a PPTP that performs IEEE 802.1X authentication of CPE (e.g., Ethernet or DSL). + +#### *Attributes* + +**Managed entity ID:** This attribute provides a unique number for each instance of this ME. Its value is the same as that of its associated PPTP (i.e., slot and port number). (R) (mandatory) (2 bytes) + +**Dot1x enable:** If true, this Boolean attribute forces the associated port to authenticate via [IEEE 802.1X] as a precondition of normal service. The default value false does not impose IEEE 802.1X authentication on the associated port. (R, W) (mandatory) (1 byte) + +**Action register:** This attribute defines a set of actions that can be performed on the associated port. The act of writing to the register causes the specified action. + +- 1 Force re-authentication – this opcode initiates an IEEE 802.1X re-authentication conversation with the associated port. The port remains in its current authorization state until the conversation concludes. +- 2 Force unauthenticated – this opcode initiates an IEEE 802.1X authentication conversation whose outcome is predestined to fail, thereby disabling normal Ethernet service on the port. The port's provisioning is not changed, such that upon re-initialization, a new IEEE 802.1X conversation may restore service without prejudice. +- 3 Force authenticated – this opcode initiates an IEEE 802.1X authentication conversation whose outcome is predestined to succeed, thereby unconditionally enabling normal Ethernet service on the port. The port's provisioning is not changed, such that upon re-initialization, a new IEEE 802.1X conversation is required. + +(W) (mandatory) (1 byte) + +**Authenticator PAE state:** This attribute returns the value of the port's PAE state. States are further described in [IEEE 802.1X]. Values are coded as follows. + +- 0 Initialize +- 1 Disconnected +- 2 Connecting +- 3 Authenticating +- 4 Authenticated +- 5 Aborting +- 6 Held +- 7 Force auth +- 8 Force unauth +- 9 Restart + +(R) (optional) (1 byte) + +**Backend authentication state:** This attribute returns the value of the port's back-end authentication state. States are further described in [IEEE 802.1X]. Values are coded as follows. + +- 0 Request +- 1 Response +- 2 Success +- 3 Fail +- 4 Timeout +- 5 Idle +- 6 Initialize +- 7 Ignore + +(R) (optional) (1 byte) + +**Admin controlled directions:** This attribute controls the directionality of the port's authentication requirement. The default value 0 indicates that control is imposed in both directions. The value 1 indicates that control is imposed only on traffic from the subscriber towards the network. (R, W) (optional) (1 byte) + +**Operational controlled directions:** This attribute indicates the directionality of the port's current authentication state. The value 0 indicates that control is imposed in both directions. The value 1 indicates that control is imposed only on traffic from the subscriber towards the network. (R) (optional) (1 byte) + +**Authenticator controlled port status:** This attribute indicates whether the controlled port is currently authorized (1) or unauthorized (2). (R) (optional) (1 byte) + +**Quiet period:** This attribute specifies the interval between EAP request/identity invitations sent to the peer. Other events such as carrier present or EAPOL start frames from the peer may trigger an EAP request/identity frame from the ONU at any time; this attribute controls the ONU's periodic behaviour in the absence of these other inputs. It is expressed in seconds. (R, W) (optional) (2 bytes) + +**Server timeout period:** This attribute specifies the time the ONU will wait for a response from the radius server before timing out. Within this maximum interval, the ONU may initiate several retransmissions with exponentially increasing delay. Upon timeout, the ONU may try another radius server if there is one, or invoke the fallback policy, if no alternate radius servers are available. Server timeout is expressed in seconds, with a default value of 30 and a maximum value of 65535. (R, W) (optional) (2 bytes) + +**Re-authentication period:** This attribute records the re-authentication interval specified by the radius authentication server. It is expressed in seconds. The attribute is only meaningful after a port has been authenticated. (R) (optional) (2 bytes) + +**Re-authentication enabled:** This Boolean attribute records whether the radius authentication server has enabled re-authentication on this service (true) or not (false). The attribute is only meaningful after a port has been authenticated. (R) (optional) (1 byte) + +**Key transmission enabled:** This Boolean attribute indicates whether key transmission is enabled (true) or not (false). This feature is not required; the parameter is listed here for completeness vis-à-vis [IEEE 802.1X]. (R, W) (optional) (1 byte) + +#### *Actions* + +Get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|--------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------| +| 0 | dot1x local authentication – allowed | No radius authentication server was accessible. In accordance with local policy, the port was allowed access without authentication. | +| 1 | dot1x local authentication – denied | No radius authentication server was accessible. In accordance with local policy, the port was denied access. | +| 2..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.3.15 Dot1X configuration profile + +An instance of this ME represents a set of attributes that control an ONU's 802.1X operation with regard to IEEE 802 services. An instance of this ME is created by the ONU if it is capable of supporting [IEEE 802.1X] authentication of CPE. + +#### Relationships + +One instance of this ME governs the ONU's 802.1X CPE authentication behaviour. + +#### Attributes + +**Managed entity ID:** This attribute provides a unique number for each instance of this ME. There is at most one instance, number 0. (R) (mandatory) (2 bytes) + +**Circuit ID prefix:** This attribute is a pointer to a large string ME whose content appears as the prefix of the NAS port ID in radius access-request messages. The remainder of the NAS port ID field is local information (for example, slot-port, appended by the ONU itself). The default value of this attribute is the null pointer 0. (R, W) (mandatory) (2 bytes) + +**Fallback policy:** When set to 1 (deny), this attribute causes IEEE 802.1X conversations to fail when no external authentication server is accessible, such that no Ethernet service is provided. The default value 0 causes IEEE 802.1X conversations to succeed when no external authentication server is accessible. (R, W) (mandatory) (1 byte) + +**Auth server 1:** This attribute is a pointer to a large string ME that contains the URI of the first choice radius authentication server. The value 0 indicates that no radius authentication server is specified. (R, W) (mandatory) (2 bytes) + +**Shared secret auth1:** This attribute is the shared secret for the first radius authentication server. It is a null-terminated character string. (R, W) (mandatory) (25 bytes) + +The following two pairs of attributes are defined in the same way: + +**Auth server 2:** (R, W) (optional) (2 bytes) + +**Shared secret auth2:** (R, W) (optional) (25 bytes) + +**Auth server 3:** (R, W) (optional) (2 bytes) + +**Shared secret auth3:** (R, W) (optional) (25 bytes) + +**OLT proxy address:** This attribute indicates the IP address of a possible proxy at the OLT for IEEE 802.1X radius messages. The default value 0.0.0.0 indicates that no proxy is required. (R, W) (optional) (4 bytes) + +**Calling station ID format:** Radius messages initiated by the ONU contain a calling-station-ID field that is specified to be the supplicant's MAC address in upper-case ASCII form, with bytes separated by a delimiter. This attribute permits specification of the delimiter. (R, W) (optional) (2 bytes) + +| Value | Meaning | +|----------------------------|---------------------------------| +| 0 | ONU's internal default | +| 1 | Hyphen (-) delimiter | +| 2 | Colon (:) delimiter | +| 3 | No delimiter | +| 0x20 – 0x7E | Use this value as the delimiter | +| 0xF0 – 0xFE | Vendor-specific use | +| Other values are reserved. | | + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### 9.3.16 Dot1X performance monitoring history data + +This ME collects performance statistics on an ONU's IEEE 802.1X CPE authentication operation. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME may be associated with each UNI that can perform IEEE 802.1X authentication of CPE. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a PPTP. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**EAPOOL frames received:** This attribute counts received valid EAPOOL frames of any type. (R) (mandatory) (4 bytes) + +**EAPOOL frames transmitted:** This attribute counts transmitted EAPOOL frames of any type. (R) (mandatory) (4 bytes) + +**EAPOOL start frames received:** This attribute counts received EAPOOL start frames. (R) (mandatory) (4 bytes) + +**EAPOOL logoff frames received:** This attribute counts received EAPOOL logoff frames. (R) (mandatory) (4 bytes) + +- Invalid EAPOL frames received:** This attribute counts received EAPOL frames in which the frame type was not recognized. (R) (mandatory) (4 bytes) +- EAP resp/id frames received:** This attribute counts received EAP response frames containing an identifier type field. (R) (mandatory) (4 bytes) +- EAP response frames received:** This attribute counts received EAP response frames, other than resp/id frames. (R) (mandatory) (4 bytes) +- EAP initial request frames transmitted:** This attribute counts transmitted request frames containing an identifier type field. In [IEEE 802.1X], this is also called ReqId. (R) (mandatory) (4 bytes) +- EAP request frames transmitted:** This attribute counts transmitted request frames, other than request/id frames. (R) (mandatory) (4 bytes) +- EAP length error frames received:** This attribute counts received EAPOL frames whose packet body length field was invalid. (R) (mandatory) (4 bytes) +- EAP success frames generated autonomously:** This attribute counts EAPOL success frames generated according to the local fallback policy because no radius server was available. (R) (mandatory) (4 bytes) +- EAP failure frames generated autonomously:** This attribute counts EAPOL failure frames generated according to the local fallback policy because no radius server was available. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|----------------------------------|--------------------------------------| +| 4 | Invalid EAPOL frames received | 5 | +| 9 | EAP length error frames received | 10 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### **9.3.17 Radius performance monitoring history data** + +This ME collects performance statistics on an ONU's radius client, particularly as related to its IEEE 802.1X operation. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an ONU. + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID (namely 0), this ME is implicitly linked to an instance of a dot1X configuration profile. (R, set-by-create) (mandatory) (2 bytes) + +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) +- Access-request packets transmitted:** This attribute counts transmitted radius access-request messages, including retransmissions. (R) (mandatory) (4 bytes) +- Access-request retransmission count:** This attribute counts radius access-request retransmissions. (R) (mandatory) (4 bytes) +- Access-challenge packets received:** This attribute counts received radius access-challenge messages. (R) (mandatory) (4 bytes) +- Access-accept packets received:** This attribute counts received radius access-accept messages. (R) (mandatory) (4 bytes) +- Access-reject packets received:** This attribute counts received radius access-reject messages. (R) (mandatory) (4 bytes) +- Invalid radius packets received:** This attribute counts received invalid radius messages. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|----------------------------------------------------------------------------------------------------------------------------|---------------------------------|--------------------------------------| +| 1 | Retransmission count | 2 | +| 5 | Invalid radius packets received | 6 | +| NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. | | | + +### **9.3.18 Dot1 rate limiter** + +This ME allows rate limits to be defined for various types of upstream traffic that are processed by IEEE 802.1 bridges or related structures. + +#### *Relationships* + +An instance of this ME may be linked to an instance of a MAC bridge service profile or an IEEE 802.1p mapper. + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) +- Parent ME pointer:** This attribute points to an instance of a ME. The type of ME is determined by the TP type attribute. (R, W, set-by-create) (mandatory) (2 bytes) + +- TP type:** This attribute identifies the type of TP associated with this dot1 rate limiter. Valid values are: +- 1 MAC bridge service profile + - 2 IEEE 802.1p mapper service profile +- (R, W, set-by-create) (mandatory) (1 byte) +- Upstream unicast flood rate pointer:** This attribute points to an instance of the traffic descriptor that governs the rate of upstream unicast packets whose DA is unknown to the bridge. A null pointer specifies that no administrative limit is to be imposed. (R, W, set-by-create) (optional) (2 bytes) +- Upstream broadcast rate pointer:** This attribute points to an instance of the traffic descriptor that governs the rate of upstream broadcast packets. A null pointer specifies that no administrative limit is to be imposed. (R, W, set-by-create) (optional) (2 bytes) +- Upstream multicast payload rate pointer:** This attribute points to an instance of the traffic descriptor that governs the rate of upstream multicast payload packets. A null pointer specifies that no administrative limit is to be imposed. (R, W, set-by-create) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.3.19 Dot1ag maintenance domain** + +In [IEEE 802.1ag], a maintenance domain (MD) is a context within which configuration fault management (CFM) connectivity verification can occur. Individual services (maintenance associations, MAs) exist within an MD. An MD is created and deleted by the OLT. The MD ME is specified by [IEEE 802.1ag] in such a way that the same provisioning can be used for all associated systems in a network; the OMCI definition accordingly avoids ONU-specific information such as pointers. + +#### *Relationships* + +Several MDs may be associated with a given bridge, at various MD levels, and a given MD may be associated with any number of bridges. + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies an instance of this ME. The values 0 and 0xFFFF are reserved. (R, set-by-create) (mandatory) (2 bytes) +- MD level:** This attribute ranges from 0..7 and specifies the maintenance level of this MD. Higher numbers have wider geographic scope. (R, W, set-by-create) (mandatory) (1 byte) +- MD name format:** This attribute specifies one of several possible formats for the MD name attribute. (R, W, set-by-create) (mandatory) (1 byte) + +| Value | MD name format | MD name attribute | Defined in | +|-------|----------------|--------------------|----------------| +| 1 | None | No MD name present | [IEEE 802.1ag] | + +| Value | MD name format | MD name attribute | Defined in | +|--------|-------------------|------------------------------------------------------------------------------------------------|---------------------------| +| 2 | DNS-like name | Globally unique text string derived from a DNS name | " | +| 3 | MAC addr and UINT | MAC address, followed by a 2-octet unsigned integer, total length 8 bytes | " | +| 4 | Character string | String of printable characters. This is recommended to be the default value. | " | +| 32 | ICC-based | ITU carrier code followed by locally assigned UMC code, 13 bytes with trailing nulls as needed | Annex A of [ITU-T Y.1731] | +| Others | Reserved | | | + +**MD name 1, MD name 2:** These two attributes may be regarded as a 50 byte octet string whose value is the left-justified maintenance domain name. The MD name may or may not be a printable character string, so an octet string is the appropriate representation. If the MD name format specifies a DNS-like name or a character string, the string is null-terminated; otherwise, its length is determined by the MD name format. If the MD has no name (MD name format = 0), this attribute is undefined. Note that binary comparisons of the MD name are made in other CFM state machines, so blanks, alphabetic case, etc., are significant. Also, note that the MD name and the MA name must be packed (with additional bytes) into 48 byte CFM message headers. (R, W) (mandatory if MD name format is not 1) (25 bytes \* 2 attributes) + +**Maintenance domain intermediate point half function (MHF) creation:** This attribute determines whether an associated bridge creates an MHF for this MD, under circumstances defined in clause 22.2.3 of [IEEE 802.1ag]. This attribute is an enumeration with the following values. + +- 1 None +- 2 Default (IEEE 802.1ag term). The bridge can create MHFs on an associated VID on any port through which the VID can pass, where: i) there are no lower active MD levels or ii) there is a maintenance association end point (MEP) at the next lower active MD level on the port. +- 3 Explicit. The bridge can create MHFs on an associated VID on any port through which the VID can pass, but only if an MEP exists at some lower maintenance level. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Sender ID permission:** This attribute determines the contents of the sender ID type-length-value (TLV) included in CFM messages transmitted by maintenance points (MPs) controlled by this MD. Chassis ID and management address information is available from the dot1ag chassis-management info ME. The attribute is an enumeration with the following values. + +- 1 None: the sender ID TLV is not to be sent. +- 2 Chassis: the chassis ID length, chassis ID subtype, and chassis ID fields of the sender ID TLV are to be sent, but not the management address fields. +- 3 Manage: the management address fields of the sender ID TLV are to be sent, but the chassis ID length is to be transmitted with the value 0, and the chassis ID subtype, and chassis ID fields are not to be sent. + +4 ChassisManage: all chassis ID and management address fields are to be sent. + +(R, W, set-by-create) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.3.20 Dot1ag maintenance association** + +This ME models an [IEEE 802.1ag] service defined on a bridge port. An MA is a set of endpoints on opposite sides of a network, all existing at a defined maintenance level. One of the endpoints resides on the local ONU; the others are understood to be configured in a consistent way on external equipment. [ITU-T Y.1731] refers to the MA as a maintenance entity group (MEG). + +An MA is created and deleted by the OLT. + +#### *Relationships* + +Any number of MAs may be associated with a given MD, or may stand on their own without an MD. One or more MAs may be associated with a MAC bridge or an IEEE 802.1p mapper. An MA exists at one of eight possible maintenance levels. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies an instance of this ME. The values 0 and 0xFFFF are reserved. (R, set-by-create) (mandatory) (2 bytes) + +**MD pointer:** This pointer specifies the dot1ag maintenance domain with which this MA is associated. A null pointer specifies that the MA is not associated with an MD. (R, W, set-by-create) (mandatory) (2 bytes) + +**Short MA name format:** This attribute specifies one of several possible formats for the short MA name attribute. Value 1, the primary VLAN ID, is recommended to be the default. (R, W, set-by-create) (mandatory) (1 byte) + +| Value | Short MA name format | Short MA name attribute | +|-------|----------------------------------|--------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Primary VID | 2 octets, 12 LSBs specify primary VID, 0 if none | +| 2 | Character string | String of up to 45 printable characters | +| 3 | 2-octet integer | 2 octet unsigned integer | +| 4 | Virtual private network (VPN) ID | 7 octets, as defined in [IETF RFC 2685] | +| 32 | ICC-based | ITU carrier code followed by locally assigned UMC code, 13 bytes with trailing nulls as needed. Defined in Annex A of [ITU-T Y.1731] | +| Other | Reserved | | + +**Short MA name 1, Short MA name 2:** These two attributes may be regarded as an octet string whose value is the left-justified MA name. Because the MA name may or may not be a printable character string, an octet string is the appropriate representation. If the short MA name format specifies a character string, the + +string is null-terminated; otherwise, its length is determined by the short MA name format. Note that binary comparisons of the short MA name are made in other CFM state machines, so blanks, alphabetic case, etc., are significant. Also, note that the MD name and the MA short name must be packed (with additional bytes) into 48 byte CFM message headers. (R, W) (mandatory) (25 bytes \* 2 attributes) + +**Continuity check message (CCM) interval:** If CCMs are enabled on an MEP, the CCM interval attribute specifies the rate at which they are generated. The MEP also expects to receive CCMs from each of the other MEPs in its CC database at this rate. + +- 0: CCM transmission disabled +- 1: 3.33 ms +- 2: 10 ms +- 3: 100 ms +- 4: 1 s +- 5: 10 s +- 6: 1 min +- 7: 10 min + +Short intervals should be used judiciously, as they can interfere with the network's ability to handle subscriber traffic. The recommended value is 1 s. (R, W, set-by-create) (mandatory) (1 byte) + +**Associated VLANs:** This attribute is a list of up to 12 VLAN IDs with which this MA is associated. Once a set of VLANs is defined, the ONU should deny operations to other dot1ag MAs or dot1ag default MD level entries that conflict with the set membership. The all-zeros value indicates that this MA is not associated with any VLANs. Assuming that the attribute is not 0, the first entry is understood to be the primary VLAN. Except forwarded linktrace messages (LTMs), CFM messages emitted by MPs in this MA are tagged with the primary VLAN ID. (R, W) (mandatory) (2 bytes/entry \* 12 entries = 24 bytes) + +**MHF creation:** This attribute determines whether the bridge creates an MHF, under circumstances defined in clause 22.2.3 of [IEEE 802.1ag]. This attribute is an enumeration with the following values: + +- 1 None. No MHFs are created on this bridge for this MA. +- 2 Default (IEEE 802.1ag term). The bridge can create MHFs on this VID on any port through which the VID can pass. +- 3 Explicit. The bridge can create MHFs on this VID on any port through which the VID can pass, but only if an MEP exists at some lower maintenance level. +- 4 Defer. This value causes the ONU to use the setting of the parent MD. This is recommended to be the default value. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Sender ID permission:** This attribute determines the contents of the sender ID TLV included in CFM messages transmitted by MPs controlled by this MA. This attribute is the same as that defined in the description of the dot1ag MD ME, with the addition of code point 5. + +- 1 None: the sender ID TLV is not to be sent. +- 2 Chassis: the chassis ID length, chassis ID subtype, and chassis ID fields of the sender ID TLV are to be sent, but not the management address fields. + +- 3 Manage: the management address fields of the sender ID TLV are to be sent, but the chassis ID length is to be transmitted with a 0 value, and the chassis ID subtype, and chassis ID fields are not to be sent. +- 4 ChassisManage: all chassis ID and management address fields are to be sent. +- 5 Defer: the contents of the sender ID TLV are determined by the corresponding MD attribute. This is recommended to be the default value. + +(R, W, set-by-create) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.3.21 Dot1ag default MD level** + +The collection of the functionality called a maintenance half-function (MHF) is not explicitly modelled as a ME by either [IEEE 802.1ag] or the OMCI. The ONU automatically creates MHFs according to parameters specified in a dot1ag MD or a dot1ag MA ME; the dot1ag default MD level ME catches the corner cases not covered by other MEs, specifically VLANs not included by any defined MA. + +The dot1ag default MD level comprises a configurable table, each entry of which specifies default MHF functionality for some set of VLANs. Once a set of VLANs is defined, operations to different table entries or to dot1ag MAs that conflict with the set membership should be denied. In addition, catch-all attributes are defined to specify MHF functionality when there is no match to either a table entry or an MA. + +#### *Relationships* + +An ONU that supports [IEEE 802.1ag] automatically creates one instance of this ME for each MAC bridge or IEEE 802.1p mapper, depending on the ONU's provisioning model. It should not create an instance for an IEEE 802.1p mapper that is associated with a MAC bridge. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies an instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge service profile ME or an IEEE 802.1p mapper ME. It is expected that an ONU will implement CFM on bridges or on IEEE 802.1p mappers, but not both, depending on its provisioning model. For precision, the reference is disambiguated by the value of the layer 2 type pointer attribute. (R) (mandatory) (2 bytes) + +**Layer 2 type:** This attribute specifies whether the dot1ag default MD level ME is associated with a MAC bridge service profile (value 0) or an IEEE 802.1p mapper (value 1). (R) (mandatory) (1 byte) + +**Catchall level:** This attribute ranges from 0..7 and specifies the MD level of MHFs created when no specific match is found. (R, W) (mandatory) (1 byte) + +**Catchall MHF creation:** This attribute determines whether, when no more specific match is found, the bridge creates an MHF or not. This attribute is an enumeration with the following values: + +- 1 None. The bridge does not create any MHFs. This is the default value. + +- 2 Default. The bridge can create MHFs on this VID on any port through which the VID can pass. +- 3 Explicit. The bridge can create MHFs on this VID on any port through which the VID can pass, but only if an MEP exists at some lower maintenance level. + +(R, W) (mandatory) (1 byte) + +**Catchall sender ID permission:** This attribute determines the contents of the sender ID TLV included in CFM messages transmitted by MPs when no more specific match is found. This attribute is identical to that defined in the description of the dot1ag MD ME (*i.e.*, excluding code point 5, defer). (R, W) (mandatory) (1 byte) + +**Default MD level table:** Each entry is a vector of fields, indexed by primary VLAN ID. + +**Primary VLAN ID** (2 bytes) + +**Table control:** This field controls the meaning of a set operation. The 1 byte size of this field is included in get/get-next operations, but its value is undefined under get-next and should be ignored by the OLT. (1 byte) + +- 1 Add record to table; overwrite existing record, if any. + - 2 Delete record from table. + - 3 Clear all entries from table. This action may affect service and should be used judiciously. +- Other values are reserved. + +**Status:** This Boolean field indicates whether this table entry is in effect (true) or whether (false) it has been overridden by the existence of an MA for the same VID and MD level as this table's entry, and on which an up MEP is defined. This attribute is read-only. Space should be allocated for it during set operations, but the value is not used. (1 byte) + +**Level:** This field ranges from 0..7 and specifies the MD level of MHFs under the control of this instance of the dot1ag default MD level. The additional value 0xFF instructs the bridge to use the value in the catch-all level attribute. (1 byte) + +**MHF creation:** This attribute determines whether the bridge creates an MHF or not, under circumstances defined in clause 22.2.3 of [IEEE 802.1ag]. This attribute is an enumeration with the following values. (1 byte) + +- 1 None. No MHFs are created on this bridge for this MA. +- 2 Default. The bridge can create MHFs on this VID on any port through which the VID can pass. +- 3 Explicit. The bridge can create MHFs on this VID on any port through which the VID can pass, but only if an MEP exists at some lower maintenance level. +- 4 Defer. This value causes the ONU to use the setting of the catch-all MHF creation attribute. This is recommended to be the default value. + +**Sender ID permission:** This attribute determines the contents of the sender ID TLV included in CFM messages transmitted by MPs controlled by this MA. (1 byte) + +- 1 None: the sender ID TLV is not to be sent, default. +- 2 Chassis: the chassis ID length, chassis ID subtype, and chassis ID fields of the sender ID TLV are to be sent, but not the management address fields. + +- 3 Manage: the management address fields of the sender ID TLV are to be sent, but the chassis ID length is to be transmitted with a 0 value, and the chassis ID subtype, and chassis ID fields are not to be sent. +- 4 ChassisManage: all chassis ID and management address fields are to be sent. +- 5 Defer: the contents of the sender ID TLV is determined by the catch-all sender ID permission attribute. + +**Associated VLANs list:** This field comprises a list of up to 11 additional VLAN IDs associated with the primary VLAN, 2 bytes each. Unused placeholders, possibly including the entire field, are set to 0. (22 bytes) + +(R, W) (mandatory) (29 bytes \* $N$ entries) + +#### *Actions* + +Get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.3.22 Dot1ag MEP** + +This ME models an MEP as defined primarily in [IEEE 802.1ag] and secondarily in [ITU-T Y.1731]. It is created and deleted by the OLT. An MEP exists at one of eight possible maintenance levels, and resides at the boundary of a MD. It inherits a name, and optionally a set of associated VLANs, from its associated MA. + +#### *Relationships* + +One or more MEPs may be associated with a MAC bridge port or an IEEE 802.1p mapper in the absence of a MAC bridge. An MEP is also associated with zero or more VLANs and an MA. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Layer 2 entity pointer:** Depending on the value of the layer 2 type attribute, this pointer specifies the MAC bridge port configuration data ME or the IEEE 802.1p mapper service profile ME with which this MEP is associated. (R, W, set-by-create) (mandatory) (2 bytes) + +**Layer 2 type:** This attribute specifies whether the MA is associated with a MAC bridge port (value 0) or an IEEE 802.1p mapper (value 1). (R, W, set-by-create) (mandatory) (1 byte) + +**MA pointer:** This pointer specifies the maintenance association with which this MEP is associated. (R, W, set-by-create) (mandatory) (2 bytes) + +**MEP ID:** This attribute specifies the MEP's own identity in the MA. For a given MA, the MEP ID must be unique throughout the network defined by the MD. The MEP ID is defined in the range 1..8191. The value 0 indicates that no MEP ID is (yet) configured. (R, W, set-by-create) (mandatory) (2 bytes) + +**MEP control:** This attribute specifies some of the overall behavioural aspects of the MEP. It is interpreted as follows. + +| Bit | Interpretation when bit value = 1 | +|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Reserved | +| 2 | MEP generates CCMs | +| 3 | Enable ITU-T Y.1731 server MEP function | +| 4 | Enable generation of Ethernet AIS | +| 5 | This is an up MEP, facing toward the core of the bridge. If more than one MEP exists on a given maintenance association and on a given bridge, all such MEPs must face the same direction. | +| 6..8 | Reserved | + +(R, W, set-by-create) (mandatory) (1 byte) + +**Primary VLAN:** This attribute is a 12 bit VLAN ID. The value 0 indicates that the MEP inherits its primary VLAN from its parent MA. CFM messages, except forwarded LTMs, are tagged with the primary VLAN ID. If explicitly specified, the value of this attribute must be one of the VLANs associated with the parent MA. (R, W, set-by-create) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W, set-by-create) (mandatory) (1 byte) + +**CCM and LTM priority:** Ranging from 0..7, this attribute permits CCM and LTM frames to be explicitly prioritized, which may be needed if flows are separated, e.g., by 802.1p priority. The priority specified in this attribute is also used in linktrace reply (LTR) frames originated by this MEP. The value 0xFF selects the IEEE 802.1ag default, whereby CCM and LTM frames are transmitted with the highest Ethernet priority available. (R, W, set-by-create) (mandatory) (1 byte) + +**Egress identifier:** This attribute comprises 8 bytes to be included in LTMs. They allow received LTRs to be directed to the correct originator. The attribute includes the originator MAC address and a locally defined identifier. If this field is 0, the ONU uses the MEP's MAC address, with 0 as the locally defined identifier. (R, W, set-by-create) (mandatory) (8 bytes) + +**Peer MEP IDs:** This attribute lists the expected peer MEPs for CCMs, 2 bytes per MEP ID. [IEEE 802.1ag] allows for multipoint networks, and therefore a list of peer MEPs. This attribute allows for up to 12 peers for a given MEP, though G-PON applications are expected to need only a single peer. Missing or unexpected messages trigger alarm declaration after a soak interval. Unused peer MEP slots should be set to 0. (R, W) (mandatory) (24 bytes) + +**ETH AIS control:** This attribute controls the generation of Ethernet alarm indication signal (AIS) frames when they are enabled through the MEP control attribute. It is interpreted as follows: + +| Bit | Interpretation | +|---------|-----------------------------------------------------------------| +| 1 (LSB) | Transmission period
0: once per second
1: once per minute | +| 2..4 | P-bit priority of transmitted ETH AIS frames | +| 5..7 | The maintenance level at which the client MEP exists | +| 8 | Reserved | + +(R, W, set-by-create) (mandatory if ETH AIS is enabled) (1 byte) + +**Fault alarm threshold:** This attribute specifies the lowest priority alarm that is allowed to generate a fault alarm. The value 0 specifies that the ONU uses its internal default. It is defined as follows. + +- 1 All defects generate alarms after suitable soaking, including AIS and RDICCM. +- 2 Alarm generated only by one of: MACstatus, RemoteCCM, ErrorCCM, XconCCM. This value is recommended as the default in [IEEE 802.1ag]. +- 3 Alarm generated only by one of: RemoteCCM, ErrorCCM, XconCCM. +- 4 Alarm generated only by one of: ErrorCCM, XconCCM. +- 5 Alarm generated only by: XconCCM. +- 6 No alarms are to be reported. This setting may be useful during configuration of services across the network when spurious alarms could otherwise be generated. + +(R, W, set-by-create) (optional) (1 byte) + +**Alarm declaration soak time:** This attribute defines the defect soak time that must elapse before the MEP declares an alarm. It is expressed in 10 ms units with a range of 250 to 1000, i.e., 2.5 s to 10 s. The default is recommended to be 2.5 seconds. (R, W) (mandatory) (2 bytes) + +**Alarm clear soak time:** This attribute defines the defect-free soak time that must elapse before the MEP clears an alarm. It is expressed in intervals of 10 ms with a range of 250 to 1 000, i.e., 2.5 s to 10 s. The default is recommended to be 10 s. (R, W) (mandatory) (2 bytes) + +#### Actions + +Create, delete, get, set + +Test: The test operation causes the MEP to originate one or more loopback messages (LBMs) or an LTM in accordance with the test and test result message formats defined in clauses A.2 and A.3. + +The linktrace test returns its results in a general purpose buffer ME, which must have been created in advance by the OLT. (The general purpose buffer is designated by a pointer in the test message itself.) Upon completion of the linktrace operation, the general purpose buffer contains a sequence of LTR entries in the order they were received: + +| Length field, 2 bytes | Length bytes | +|------------------------------|--------------------------------------------------------| +| Length of LTR1 | LTR: linktrace reply 1 (clause 21.9 of [IEEE 802.1ag]) | +| Length of LTR2 | LTR: linktrace reply 2 | +| etc. | | + +[IEEE 802.1ag] defines the data structure for the linktrace database in detail, but the definition is essentially the same as the LTR protocol data unit (PDU) itself. The OMCI simply records the messages for parsing and analysis at the OLT or the element management system (EMS). + +If the ONU cannot allocate enough memory for the entire list, it keeps the most recent responses and discards the older LTRs as necessary (first discarding LTR1, then LTR2, etc.). + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|---------------------|------------------------|--------------------------------------------------| +| 0 | RDI CCM | RDI received in CCM from peer MEP | +| 1 | MAC status | Port or interface status failure at peer MEP | +| 2 | Remote CCM | Loss of continuity with peer MEP | +| 3 | Error CCM | Invalid CCMs received | +| 4 | Xcon CCM | CCMs received from other MAs or a lower MD level | +| 5 | Unexpected period | Unexpected period | +| 6 | AIS | Ethernet AIS received | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.3.23 Dot1ag MEP status + +This ME is the read-only twin of the dot1ag MEP. Its purpose is to return information that may help in system- or network-level troubleshooting. It is automatically created and deleted by the ONU at the time its MEP is created or deleted. + +As the reporter of ephemeral information, the dot1ag MEP status ME does not retain its attribute values across initializations and is not included in MIB uploads. + +#### Relationships + +A dot1ag MEP status ME is associated with a dot1ag MEP ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the dot1ag MEP ME. (R) (mandatory) (2 bytes) + +**MEP MAC address:** This attribute records the MEP's MAC address. (R) (mandatory) (6 bytes) + +**Fault notification generator state:** This attribute records the current state of the MEP's fault notification generator state machine. States are defined in clause 20.35 of [IEEE 802.1ag]. + +- 1 Reset +- 2 Defect +- 3 Report defect +- 4 Defect reported +- 5 Defect clearing + +(R) (mandatory) (1 byte) + +**Highest priority defect observed:** This attribute records the highest priority defect observed since the fault notification state machine was last in reset state. In increasing priority order, possible values are as follows. + +- 0 No defect observed +- 1 Received a CCM from a remote MEP in which the remote defect indication (RDI) bit was set +- 2 Received a CCM from a remote MEP in which the port status or interface status TLV reported an error +- 3 No CCMs received for at least $3.5 \times \text{CCM interval}$ from at least one remote MEP in the MA +- 4 Received invalid CCMs for at least $3.5 \times \text{CCM interval}$ +- 5 Received CCMs for at least $3.5 \times \text{CCM interval}$ that could be from another MA + +(R) (mandatory) (1 byte) + +**Current defects:** This attribute is a bit field that signals several events of interest in real time. + +| Bit | Meaning when set | +|---------|----------------------------------------------------------------------------------------------------------------------------------| +| 1 (LSB) | Another MEP in the same MA is currently transmitting an RDI. | +| 2 | A port status or interface status TLV received from another MEP in the MA is currently indicating an error condition. | +| 3 | CCMs have not been received for at least $3.5 \times \text{CCM interval}$ from at least one of the expected remote MEPs. | +| 4 | Erroneous CCMs have been received for at least $3.5 \times \text{CCM interval}$ from at least one of the remote MEPs in this MA. | +| 5 | CCMs have been received for at least $3.5 \times \text{CCM interval}$ from an MEP that is not configured into the current MA. | +| 6..8 | Reserved | + +(R) (mandatory) (1 byte) + +**Last received errored CCM table:** This attribute contains the most recently received CCM that contributed to a defErrorCCM fault. If no such CCM has been received, this attribute is null. The format of the CCM is defined in clause 21.6 of [IEEE 802.1ag]. (R) (mandatory) (*N* bytes, not to exceed 128) + +**Last received Xcon CCM table:** This attribute contains the most recently received CCM that contributed to a defXconCCM fault. If no such CCM has been received, this attribute is null. (R) (mandatory) (*N* bytes, not to exceed 128) + +**Out of sequence CCMs count:** This attribute records the number of out of sequence CCMs received. When the counter is full, it rolls over to 0. (R) (optional) (4 bytes) + +**CCMs transmitted count:** This attribute records the number of CCMs transmitted. It may be used as the sequence number of transmitted CCMs. When the counter is full, it rolls over to 0. (R) (mandatory) (4 bytes) + +**Unexpected LTRs count:** This attribute records the number of unexpected LTRs received. When the counter is full, it rolls over to 0. (R) (mandatory) (4 bytes) + +**Loopback replies (LBRs) transmitted count:** This attribute records the number of LBRs transmitted. When the counter is full, it rolls over to 0. (R) (mandatory) (4 bytes) + +**Next loopback transaction identifier:** This attribute is the value of the transaction number sent in the next LBM to be transmitted. At ONU initialization, it should be initialized to a random value. It increments with each LBM sent, and rolls over when full. (R) (mandatory) (4 bytes) + +**Next linktrace transaction identifier:** This attribute is the value of the transaction number sent in the next LTM to be transmitted. It increments with each LTM sent, and rolls over when full. (R) (mandatory) (4 bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. This ME does not generate AVCs because its attributes change frequently in real time, but are generally only of interest after the corresponding MEP declares an alarm. + +### **9.3.24 Dot1ag MEP CCM database** + +This ME records the recent history of remote MEPs, as deduced by the local parent MEP. Because records are of variable length, and are constantly updated, a separate attribute is defined for each remote MEP. The dot1ag MEP CCM database is automatically created or deleted by the ONU at the time an MEP is created or deleted. + +As the reporter of ephemeral information, the dot1ag MEP CCM database ME does not retain its attribute values across initializations and is not included in MIB uploads. + +#### *Relationships* + +A dot1ag MEP CCM database ME is associated with a dot1ag MEP ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the dot1ag MEP ME. (R) (mandatory) (2 bytes) + +Each of the following RMEP database table attributes records information for one of the possible remote MEPs. It is expected that there will be only one remote MEP per MA in G-PON applications, but the ME is defined in a way that permits several RMEPs. The optional attributes are instantiated by the ONU when additional remote MEPs are provisioned on the local MEP. Remote MEP records appear in no particular order, and the order is not guaranteed to persist across ONU initializations. + +NOTE – Although each attribute is shown with a single indeterminate length *N*, it is understood that the length of each attribute varies in real time, and independently from the length of the other attributes. + +**RMEP 1 database table:** (R) (mandatory) (*N* bytes) + +**RMEP 2 database table:** (R) (optional) (*N* bytes) + +**RMEP 3 database table:** (R) (optional) (*N* bytes) + +**RMEP 4 database table:** (R) (optional) (*N* bytes) + +**RMEP 5 database table:** (R) (optional) (*N* bytes) + +**RMEP 6 database table:** (R) (optional) (*N* bytes) + +**RMEP 7 database table:** (R) (optional) (*N* bytes) + +**RMEP 8 database table:** (R) (optional) (*N* bytes) + +**RMEP 9 database table:** (R) (optional) (*N* bytes) + +**RMEP 10 database table:** (R) (optional) (*N* bytes) + +**RMEP 11 database table:** (R) (optional) (*N* bytes) + +**RMEP 12 database table:** (R) (optional) (*N* bytes) + +Each attribute is a record that comprises the following fields. + +**RMep identifier:** The MEP ID of the remote MEP. (2 bytes) + +**RMep state:** An enumeration with the following meaning (1 byte). + +- 1 Idle. Momentary state during reset. +- 2 Start. The timer has not expired since the state machine was reset, but no valid CCM has yet been received. +- 3 Failed. The timer has expired since the state machine was reset and since a valid CCM was received. +- 4 Ok. The timer has not expired since a valid CCM was received. + +**Failed-ok time:** A timestamp, the value of the local ONU's SysUpTime at which the remote MEP state last entered either the failed or ok state. SysUpTime is a count of 10 ms intervals since ONU initialization. The value is 0 if it has not been in either of these states since ONU initialization. (4 bytes) + +**MAC address:** The MAC address of the remote MEP. If no CCM has been received from the remote MEP, this field has the value 0. (6 bytes) + +**RDI:** Boolean indicating whether the RDI bit in the most recently received CCM was set. (1 byte) + +**Port status:** The port status from the most recently received CCM, as defined in clause 21.5.4 of [IEEE 802.1ag]. The absence of a received port status TLV is indicated by the value 0. (1 byte) + +**Interface status:** The interface status from the most recently received CCM, as defined in clause 21.5.5 of [IEEE 802.1ag]. The absence of a received interface status TLV is indicated by the value 0. (1 byte) + +**Sender ID TLV:** This is the actual sender ID TLV from the most recently received CCM, as defined in clause 21.5.3 of [IEEE 802.1ag]. The absence of a received sender ID TLV is indicated by a single byte of value 0. (*M* bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. The MEP CCM database table attributes do not generate AVCs because they change constantly in real time, usually in ways that are of no immediate interest. + +### **9.3.25 Dot1ag CFM stack** + +This ME reports the maintenance status of a bridge port at any given time. An ONU that supports [IEEE 802.1ag] functionality automatically creates an instance of the dot1ag CFM stack ME for each MAC bridge or IEEE 802.1p mapper, depending on its provisioning model. + +The dot1ag CFM stack also lists any VLANs and bridge ports against which configuration errors are currently identified. The ONU should reject operations that create configuration errors. However, these errors can arise because of operations on other MEs that are not necessarily possible to detect during CFM configuration. + +#### Relationships + +An ONU that supports [IEEE 802.1ag] creates one instance of this ME for each MAC bridge or IEEE 802.1p mapper, depending on its provisioning model. It should not create an instance for an IEEE 802.1p mapper that is associated with a MAC bridge. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies an instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge service profile ME or an IEEE 802.1p mapper ME. It is expected that an ONU will implement CFM on bridges or on IEEE 802.1p mappers, but not both. For precision, the reference is disambiguated by the value of the layer 2 type pointer attribute. (R) (mandatory) (2 bytes) + +**Layer 2 type:** This attribute specifies whether the dot1ag CFM stack is associated with a MAC bridge service profile (value 0) or an IEEE 802.1p mapper (value 1). (R) (mandatory) (1 byte) + +**MP status table:** This attribute is a list of entries, each entry reporting one aspect of the maintenance status of one port. If a port is associated with more than one CFM maintenance entity, each is represented as a separate item in this table attribute; a port that has no current maintenance functions is not represented in the table (so the table may be empty). Each entry is defined as follows. + +**Port ID:** The ME ID of the MAC bridge port config data whose information is reported in this entry. If the layer 2 parent is an IEEE 802.1p mapper, a null pointer. (2 bytes) + +**Level:** The level at which the reported maintenance function exists, 0..7. (1 byte) + +**Direction:** The value 1 (down) or 2 (up). (1 byte) + +**VLAN ID:** If this table entry reports a maintenance function associated with a VLAN, this field contains the value of the primary VLAN ID. If no VLAN is associated with this entry, this field contains the value 0. (2 bytes) + +**MD:** A pointer to the associated dot1ag maintenance domain ME. If no MD is associated with this entry, a null pointer. (2 bytes) + +**MA:** A pointer to the associated dot1ag maintenance association ME. If no MA is associated with this entry, a null pointer. (2 bytes) + +**MEP ID:** If this table entry reports an MEP, this field contains the value of its MEP ID (range 1..8191). If this table entry reports an MHF, this field contains the value 0. (2 bytes) + +**MAC address:** The MAC address of the MP. (6 bytes) + +(R) (mandatory) (18N bytes) + +**Configuration error list table:** This attribute is based on the [IEEE 802.1ag] configuration error list. It is a list of entries, each entry reporting a VLAN and a bridge port against which a configuration error has been detected. The table may be empty at any given time. Entries are defined as follows: + +**VLAN ID:** If this table entry reports a maintenance function associated with a VLAN, this field contains the value of the VLAN ID in error. If no VLAN is associated with this entry, this field contains the value 0. (2 bytes) + +**Port ID:** A pointer to the MAC bridge port config data whose information is reported in this entry. If the layer 2 parent is an IEEE 802.1p mapper, a null pointer. (2 bytes) + +**Detected configuration error:** A bit mask with the following meanings. A list entry exists if and only if at least one of these bits is set. Definitions appear in clause 22.2.4 of [IEEE 802.1ag]: (1 byte) + +- 0x01 CFM leak. MA x is associated with a specific VID list, one or more of the VIDs in MA x can pass through the bridge port, no up MEP is configured for MA x on the bridge port, no down MEP is configured on any bridge port for MA x, and another MA y, at a higher MD level than MA x, and associated with at least one of the VID(s) also in MA x, does have an MEP configured on the bridge port. +- 0x02 Conflicting VIDs. MA x is associated with a specific VID list, an up MEP is configured on MA x on the bridge port, and another MA y, associated with at least one of the VID(s) also in MA x, and at the same MD level as MA x, also has an up MEP configured on some bridge port. +- 0x04 Excessive levels. The number of different MD levels at which maintenance domain intermediate points (MIPs) are to be created on this port exceeds the bridge's capabilities. +- 0x08 Overlapped levels. An MEP is created for one VID at one MD level, but an MEP is also configured on another VID at that MD level or higher, exceeding the bridge's capabilities. + +(R) (mandatory) (5N bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|-------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1..2 | N/A | | +| 3 | Config error list table | This AVC indicates that an entry in the configuration error list table has been added or removed. It may be advisable for the OLT to audit the configuration of related MEs. | +| 4..16 | Reserved | | + +### **9.3.26 Dot1ag chassis-management info** + +This ME represents the system-level chassis ID or management address for [IEEE 802.1ag] CFM messages, and potentially for other IEEE 802-based functions. Although [IEEE 802.1AB] allows for several management addresses (synonyms in different formats or with granularity to the component level), [IEEE 802.1ag] does not provide for more than one. Nor is it expected that an ONU would require more than one format. Accordingly, this ME provides for only one. + +According to sender ID permission attributes in several dot1ag MEs, transmitted IEEE 802.1ag CFM messages may include either or both of the chassis ID or management address fields. [IEEE 802.1ag] requires that CCMs do not exceed 128 bytes, of which 74 are separately allocated to other purposes; the sender ID TLV, if present, must accommodate this requirement. The chassis info and management + +info must fit, with a minimum of 4 additional overhead bytes, into the remaining 54 bytes. This limit is exploited in defining the maximum size of the ME's attributes. + +#### Relationships + +If an ONU supports [IEEE 802.1ag] functionality, it automatically creates an instance of this ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies this ME. There is at most one instance, whose value is 0. (R) (mandatory) (2 bytes) + +**Chassis ID length:** The length of the chassis ID attribute (not including the chassis ID subtype attribute), default value 0. (R, W) (mandatory) (1 byte) + +**Chassis ID subtype:** The format of the chassis ID attribute, default value 7, as defined in [IEEE 802.1AB]: + +| | | | +|---|-------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Chassis component | A particular instance of the entPhysicalAlias object (defined in [IETF RFC 4133]) for a chassis component. | +| 2 | Interface alias | A particular instance of the ifAlias object (defined in [IETF RFC 2863]) for an interface on the containing chassis. | +| 3 | Port component | A particular instance of the entPhysicalAlias object (defined in [IETF RFC 4133]) for a port or backplane component within the containing chassis. | +| 4 | Mac address | A particular unicast source address (encoded in network byte order and IEEE 802.3 canonical bit order), of a port on the containing chassis as defined in [IEEE 802]. | +| 5 | Network address | A particular network address, encoded in network byte order, associated with one or more ports on the containing chassis. The first octet contains the Internet Assigned Numbers Authority [b-IANA] address family numbers enumeration value for the specific address type, and octets 2 to N contain the network address value in network byte order. | +| 6 | Interface name | A particular instance of the ifName object (defined in [IETF RFC 2863]) for an interface on the containing chassis. | +| 7 | Local | Locally assigned chassis ID | + +(R, W) (mandatory) (1 byte) + +**Chassis ID part 1, Chassis ID part 2:** These two attributes may be regarded as an octet string of up to 50 bytes whose length is given by the chassis ID length attribute and whose value is the left-justified chassis ID. (R, W) (mandatory) (25 bytes \* 2 attributes) + +**Management address domain length:** The length of the management address domain attribute, default value 0. If this attribute has the value 0, all of the other management address attributes are undefined. (R, W) (mandatory) (1 byte) + +**Management address domain 1, Management address domain 2:** These two attributes may be regarded as an octet string of up to 50 bytes whose length is given by the management address domain length attribute and whose value is the left-justified management address domain. The attribute is coded as an object identifier (OID) as per [ITU-T X.690], referring to a TDomain as defined in [IETF RFC 2579]. Typical domain values include snmpUDPDomain (from + +SNMPv2-TM [IETF RFC 3417]) and snmpIeee802Domain (from SNMP-IEEE 802-TM-MIB [IETF RFC 4789]). (R, W) (mandatory) (25 bytes \* 2 attributes) + +**Management address length:** The length of the management address attribute, default value 0. (R, W) (mandatory) (1 byte) + +**Management address 1, Management address 2:** These two attributes may be regarded as an octet string of up to 50 bytes whose length is given by the management address length attribute and whose value is the left-justified management address. (R, W) (mandatory) (25 bytes \* 2 attributes) + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.3.27 Multicast operations profile** + +This ME expresses multicast policy. A multi-dwelling unit ONU may have several such policies, which are linked to subscribers as required. Some of the attributes configure IGMP snooping and proxy parameters if the defaults do not suffice, as described in [IETF RFC 2236], [IETF RFC 3376], [IETF RFC 3810] and [IETF RFC 5519]. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the multicast subscriber config info ME. + +##### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The values 0 and 0xFFFF are reserved. (R, set-by-create) (mandatory) (2 bytes) + +**IGMP version:** This attribute specifies the version of IGMP to be supported. Support of a given version implies compatible support of previous versions. If the ONU cannot support the version requested, it should deny an attempt to set the attribute. (R, W, set-by-create) (mandatory) (1 byte) + +| | | +|----------------------------|-----------------------------| +| 1 | IGMP version 1 (deprecated) | +| 2 | IGMP version 2 | +| 3 | IGMP version 3 | +| 16 | MLD version 1 | +| 17 | MLD version 2 | +| Other values are reserved. | | + +**IGMP function:** This attribute enables an IGMP function. The value 0 specifies transparent IGMP snooping only. The value 1 specifies snooping with proxy reporting (SPR); the value 2 specifies IGMP proxy. The function must be consistent with the capabilities specified by the other IGMP configuration attributes. (R, W, set-by-create) (mandatory) (1 byte) + +**Immediate leave:** This Boolean attribute controls the immediate leave function. The value false disables immediate leave; true enables immediate leave. (R, W, set-by-create) (mandatory) (1 byte) + +**Upstream IGMP TCI:** Under control of the upstream IGMP tag control attribute, the upstream IGMP TCI attribute defines a VLAN ID and P-bits to add to upstream IGMP messages. (R, W, set-by-create) (optional) (2 bytes) + +**Upstream IGMP tag control:** This attribute controls the upstream IGMP TCI attribute. If this attribute is non-zero, a possible extended VLAN tagging operation ME is ignored for upstream frames containing IGMP/MLD packets. (R, W, set-by-create) (optional) (1 byte) + +| Value | Meaning | +|-------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Pass upstream IGMP/MLD traffic transparently, neither adding, stripping nor modifying tags that may be present. | +| 1 | Add a VLAN tag (including P bits) to upstream IGMP/MLD traffic. The tag is specified by the upstream IGMP TCI attribute. | +| 2 | Replace the entire TCI (VLAN ID plus P bits) on upstream IGMP/MLD traffic. The new tag is specified by the upstream IGMP/MLD TCI attribute. If the received IGMP/MLD traffic is untagged, an add operation is performed. | +| 3 | Replace only the VLAN ID on upstream IGMP/MLD traffic, retaining the original DEI and P bits. The new VLAN ID is specified by the VLAN ID field of the upstream IGMP TCI attribute. If the received IGMP/MLD traffic is untagged, an add operation is performed, with DEI and P bits also taken from the upstream IGMP TCI attribute. | + +Other values are reserved. + +**Upstream IGMP rate:** This attribute limits the maximum rate of upstream IGMP traffic. Traffic in excess of this limit is silently discarded. The attribute value is specified in messages/second. The recommended default value 0 imposes no rate limit on this traffic. (R, W, set-by-create) (optional) (4 bytes) + +**Dynamic access control list table:** This attribute is a list that specifies one or more multicast group address ranges. Each row in the list comprises up to three row parts, where each row part is 24 bytes long. Each entry must include row part 0. The ONU may also support row parts 1-2, thus allowing the table to contain logical rows that exceed the 24 byte definition of row part 0. + +**Table control (2 bytes)** + +| | | | | | | | | | | | | | | | | +|----------|----|-------------|----|----|------|---------|---|---|---|---|---|---|---|---|---| +| 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| Set ctrl | | Row part ID | | | Test | Row key | | | | | | | | | | + +The first 2 bytes of each row part is the table control field, which comprises a key into the row, the row part identifier, and fields to define the result of a set operation and to test whether the ONU supports the extended table format. + +It is the responsibility of the OLT to assign and track row keys and content. The ONU should deny set operations that create range overlaps. + +##### **Set ctrl** + +The two MSBs of this field determine the meaning of a set operation. These bits are returned as 00 during get next operations. + +| Bits 16..15 | Meaning | +|-------------|------------------------------------------------------------------------------------------------------| +| 00 | Reserved | +| 01 | Write this entry into the table. Overwrite any existing entry with the same row part ID and row key. | +| 10 | Delete this entry from the table, including all row parts. The remaining fields are not meaningful. | + +| Bits 16..15 | Meaning | +|-------------|----------------------------------------------------------------------------| +| 11 | Clear all entries from the table. The remaining fields are not meaningful. | + +##### Row part ID + +The row part ID field distinguishes the row part associated with the current set or get operation. + +Row part 0 is backward compatible with earlier versions of this ME definition. Row parts 1-2 are optional on a row by row basis. They can be set by using values 001-010 as the row part ID. Row parts 3-7 are reserved. + +| Bits 14..12 | Meaning | +|-------------|---------------------------------------| +| 000 | The associated row part has format 0. | +| 001 | The associated row part has format 1. | +| 010 | The associated row part has format 2. | +| 011..111 | Reserved | + +##### Test + +This bit allows the OLT to determine whether an ONU supports the extended format access control list. If the ONU does not support the extended format, it should be possible to set the test bit to 1 and read it back with a get and get next operation. If the ONU does support the extended format, this bit should always return the value 0 under a get next operation. + +##### Row key + +The row key distinguishes rows in the table. + +##### Row part definition + +| Byte | Row part 0 | Row part 1 | Row part 2 | +|------|--------------------------------------------------------|-------------------------------------------------------|---------------------------------------------------------------| +| 1 | Table control
(2 bytes) | Table control
(2 bytes) | Table control
(2 bytes) | +| 2 | | | | +| 3 | GEM port ID
(2 bytes) | Leading bytes of
IPv6 source address
(12 bytes) | Leading bytes of
IPv6 destination
address
(12 bytes) | +| 4 | | | | +| 5 | VLAN ID (ANI)
(2 bytes) | | | +| 6 | | | | +| 7 | Source IP address
(4 bytes) | | | +| 8 | | | | +| 9 | | | | +| 10 | | | | +| 11 | Destination IP address,
start of range
(4 bytes) | | | +| 12 | | | | +| 13 | | | | +| 14 | | | | +| 15 | | Preview length
(2 bytes) | Reserved
(10 bytes) | +| 16 | | | | + +| Byte | Row part 0 | Row part 1 | Row part 2 | +|------|------------------------------------------------------|-----------------------------------|------------| +| 17 | Destination IP address,
end of range
(4 bytes) | Preview repeat time
(2 bytes) | | +| 18 | | | | +| 19 | Imputed group
bandwidth
(4 bytes) | Preview repeat count
(2 bytes) | | +| 20 | | | | +| 21 | | Preview reset
time (2 bytes) | | +| 22 | | | | +| 23 | Reserved
(2 bytes) | Reserved
(2 bytes) | | +| 24 | | | | + +**Figure 9.3.27-1 – ACL row part formats** + +Format of row part 0: + +- Table control (2 bytes) +- GEM port-ID (2 bytes) +- VLAN ID (ANI). This field specifies the VLAN carrying the multicast group downstream. + +Values: + +0 – Designates an untagged downstream flow. + +1..4095 – Matched against the VID of the downstream multicast frame. + +4096 – Reserved. + +4097 – Matches downstream tagged messages only, but ignores the value of the VID. + +0xFFFF – Unspecified. + +(2 bytes) + +- Source IP address. The value 0.0.0.0 specifies that the source IP address is to be ignored. By default, this is an IPv4 address; it may be an IPv6 address if it is associated with a part 1 row. (4 bytes) +- Destination IP address of the start of the multicast range. By default, this is an IPv4 address; it may be an IPv6 address if it is associated with a part 2 row. (4 bytes) +- Destination IP address of the end of the multicast range. By default, this is an IPv4 address; it may be an IPv6 address if it is associated with a part 2 row. (4 bytes) +- Imputed group bandwidth. Expressed in bytes per second, the imputed group bandwidth is used to decide whether or not to honour a join request in the presence of a max multicast bandwidth limit. The recommended default value 0 effectively allows this table entry to avoid max bandwidth limitations (4 bytes) +- Reserved, set to 0. (2 bytes) + +A single multicast group may be specified by setting start and end destination IP addresses to the same value. + +Format of row part 1: + +- Table control (2 bytes) + +- The leading bytes of the IPv6 source address (12 bytes). This field is prepended to the 4 byte source IP address field of the corresponding part 0 row. The row part 0 address field is interpreted as an IPv4 address if the first 10 bytes of this row part 1 field are 0 and the last 2 bytes are either 0 or 0xFFFF [b-IETF RFC 4291]. The latter syntax is preferred. +- Preview length. The maximum duration of each preview in seconds. The value 0 designates a group that is fully authorized by subscription and is not subject to preview restrictions. The remaining preview attributes in this row part are ignored. (2 bytes) +- Preview repeat time. The minimum time in seconds between two previews of a given multicast group. (2 bytes) +- Preview repeat count. The maximum number of times a given multicast group may be previewed. A value of zero allows an unlimited number of previews. (2 bytes) +- Preview reset time. The time at which the ONU resets the preview repeat counter. The value assignments are as follows: (2 bytes) + - 0: Do not reset the preview repeat counter automatically. It is cleared only upon explicit action by the OLT. + - 1..24: The integer clock time at which the ONU resets the preview repeat counter. For example the value 2 resets the counter at 02:00 AM. If the ONU does not have a time of day clock, the preview repeat counter is reset every 24 h at an indeterminate time selected by the ONU. + - 25..240: Reserved by ITU + - 241..254: Reserved for vendor-specific use + - 255: Used by the OLT to explicitly reset the preview repeat counter. A set action with this value clears the preview repeat count to zero, but does not alter the pre-existing value of the field in the table row part. +- Reserved (2 bytes) + +Format of row part 2: + +- Table control (2 bytes) +- The leading bytes of the IPv6 DAs (12 bytes). This field is prepended to the 4 byte destination IP address field of the corresponding part 0 row. The row part 0 address field is interpreted as an IPv4 address if the first 10 bytes of this row part 2 field are 0 and the last 2 bytes are either 0 or 0xFFFF [b-IETF RFC 4291]. The latter syntax is preferred. +- Reserved (10 bytes) + +(R, W) (mandatory) (each row part: 24 bytes) + +**Discussion of table size:** While theoretically, this table could contain 1024 entries, real-world applications are not expected to require large tables. It is instead anticipated that the table will list a moderate number of contiguous ranges, each of which shares a common GEM port, VLAN, IP source address, imputed bandwidth, and preview characteristics. The ONU maintains preview counters and interval timers on a per-multicast group basis, not collectively for the entire range. + +**Static access control list table:** This attribute is a list that specifies one or more multicast group address ranges. Groups defined in this list are multicast on the associated UNI(s) unconditionally, i.e., without the need for an IGMP join. The + +bandwidth of static multicast groups is not included in the current multicast bandwidth measurement maintained by the multicast subscriber monitor ME. If a join message is always expected, this table may be empty. Table entries have the same format as those in the dynamic access control list table. The preview fields are not meaningful. (R, W) (mandatory) (each row part: 24 bytes) + +**Lost groups list table:** This attribute is a list of groups from the dynamic access control list table for which there is an active join, but no downstream flow is present, possibly because of source failure, but also possibly because of misconfiguration somewhere upstream. Be aware of possible ambiguity between overlapping service providers and IPv4/IPv6 addresses. After a join, the ONU should wait a reasonable time for upstream processing before declaring a group to be lost. Each entry is a vector of the following components: + +- VLAN ID, 0 if not used (2 bytes) +- Source IP address, 0.0.0.0 if not used. In IPv6, this field captures only the four least significant bytes. (4 bytes) +- Multicast destination IP address. In IPv6, this field captures only the four least significant bytes. (4 bytes) + +(R) (optional) (10N bytes) + +**Robustness:** This attribute allows tuning for possible packet loss in the network. The recommended default value 0 causes the ONU to follow [IETF RFC 3376] to copy the robustness value from query messages originating further upstream. (R, W, set-by-create) (optional) (1 byte) + +**Querier IP address:** This attribute specifies the IP address to be used by a proxy querier. Although it is not a legitimate IP address, the recommended default value 0.0.0.0 is legal in this case (see [b-IETF RFC 4541]). (R, W, set-by-create) (optional) (4 bytes) + +**Query interval:** This attribute specifies the interval between general queries in seconds. The value 0 specifies that the ONU uses its own default, which may or may not be the same as the recommended default of 125 s. (R, W, set-by-create) (optional) (4 bytes) + +**Query max response time:** This attribute is the max response time added by the proxy into general query messages directed to UNIs. It is expressed in units of 0.1 s. The value 0 specifies that the ONU uses its own default, which may or may not be the same as the recommended default of 100 (10 s). (R, W, set-by-create) (optional) (4 bytes) + +**Last member query interval:** This attribute specifies the maximum response time inserted into group-specific queries sent to UNIs in response to group leave messages. It is also the repetition rate of [robustness] transmissions of the query. It is specified in units of 0.1 s, with a default of 10 (1 s). (R, W) (optional) (4 bytes) + +**Unauthorized join request behaviour:** This Boolean attribute specifies the ONU's behaviour when it receives an IGMP join request for a group that is not authorized in the dynamic address control list table, or an IGMPv3 membership report for groups, none of which are authorized in the dynamic ACL. The default value false specifies that the ONU silently discard the IGMP request; the value true specifies that the ONU forwards the request upstream. The ONU does not attempt to honour the request for the unauthorized group(s) in either case. (R, W) (optional) (1 byte) + +**Downstream IGMP and multicast TCI:** This attribute controls the downstream tagging of both the IGMP/MLD and multicast frames. If the first byte of this attribute is non-zero, a possible extended VLAN tagging operation ME is ignored for downstream IGMP/MLD and multicast frames. (R, W, set-by-create) (optional) (3 bytes) + +The first byte defines the control type: + +| Value | Meaning | +|-------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Pass the downstream IGMP/MLD and multicast traffic transparently, neither stripping nor modifying tags that may be present. | +| 1 | Strip the outer VLAN tag (including P bits) from the downstream IGMP/MLD and multicast traffic. | +| 2 | Add a tag on to the downstream IGMP/MLD and multicast traffic. The new tag is specified by the second and third bytes of this attribute. | +| 3 | Replace the tag on the downstream IGMP/MLD and multicast traffic. The new tag is specified by the second and third bytes of this attribute. | +| 4 | Replace only the VLAN ID on the downstream IGMP/MLD and multicast traffic, retaining the original DEI and P bits. The new VLAN ID is specified by the VLAN ID field of the second and third bytes of this attribute. | +| 5 | Add a tag on to the downstream IGMP/MLD and multicast traffic. The new tag is specified by the VID (UNI) field of the multicast service package table row of the multicast subscriber config info ME that is associated with this profile. If the VID (UNI) field is unspecified (0xFFFF) or specifies untagged traffic, the new tag is specified by the second and third bytes of this attribute. | +| 6 | Replace the tag on the downstream IGMP/MLD and multicast traffic. The new tag is specified by the VID (UNI) field of the multicast service package table row of the multicast subscriber config info ME that is associated with this profile. If the VID (UNI) field specifies untagged traffic, the outer VLAN tag (including P bits) is stripped from the downstream IGMP/MLD and multicast traffic. If the value of the VID (UNI) is unspecified (0xFFFF), the new tag is specified by the second and third bytes of this attribute. | +| 7 | Replace only the VID on the downstream IGMP/MLD and multicast traffic, retaining the original DEI and P bits. The new VLAN ID is specified by the VID (UNI) field of the multicast service package table row of the multicast subscriber config info ME that is associated with this profile. If the VID (UNI) field specifies untagged traffic, the outer VLAN tag (including P bits) is stripped from the downstream IGMP/MLD and multicast traffic. If the value of the VID (UNI) is unspecified (0xFFFF), the new tag is specified by the second and third bytes of this attribute. | + +Other values are reserved. + +The second and third bytes define the TCI (VLAN ID and P bits) to be applied on the downstream IGMP/MLD and multicast streams in case the replace or add option is selected. + +#### Actions + +Create, delete, get, get next, set + +Set table (optional) + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Lost multicast group | Indicates that for one or more multicast groups, there is an active join, but no downstream flow is present. This alarm is equivalent to a non-zero number of entries in the lost groups list table attribute. When the alarm is active, the OLT may use the table to retrieve the details of the lost group(s). | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.3.28 Multicast subscriber config info + +This ME organizes data associated with multicast management at subscriber ports of IEEE 802.1 bridges, including IEEE 802.1p mappers when the provisioning model is mapper-based rather than bridge-based. Instances of this ME are created and deleted by the OLT. Because of backward compatibility considerations, a subscriber port without an associated multicast subscriber config info ME would be expected to support unrestricted multicast access; this ME may therefore be viewed as restrictive, rather than permissive. + +Through separate attributes, this ME supports either a single multicast operations profile in its backward compatible form, or a list of multicast operations profiles instead (the list may of course contain a single entry). The OLT can determine whether the ONU supports the multiple profile capability by performing a get operation on the optional multicast service package table attribute, which exists only on ONUs that are prepared to support the feature. + +#### Relationships + +An instance of this ME is associated with one instance of the MAC bridge port configuration data or the IEEE 802.1p mapper service profile. + +##### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data or IEEE 802.1p mapper ME. (R, set-by-create) (mandatory) (2 bytes) + +**ME type:** This attribute indicates the type of the ME implicitly linked by the ME ID attribute. + +- 0 MAC bridge port config data +- 1 IEEE 802.1p mapper service profile + +(R, W, set-by-create) (mandatory) (1 byte) + +**Multicast operations profile pointer:** This attribute points to an instance of the multicast operations profile. This attribute is ignored by the ONU if a non-empty multicast service package table attribute is present. (R,W, set-by-create) (mandatory) (2 bytes) + +**Max simultaneous groups:** This attribute specifies the maximum number of dynamic multicast groups that may be replicated to the client port at any one time. The recommended default value 0 specifies that no administrative limit is to be imposed. (R, W, set-by-create) (optional) (2 bytes) + +**Max multicast bandwidth:** This attribute specifies the maximum imputed dynamic bandwidth, in bytes per second, that may be delivered to the client port at any one time. The recommended default value 0 specifies that no administrative limit is to be imposed. (R, W, set-by-create) (optional) (4 bytes) + +**Bandwidth enforcement:** The recommended default value of this Boolean attribute is false, and specifies that attempts to exceed the max multicast bandwidth be counted but honoured. The value true specifies that such attempts be counted and denied. The imputed bandwidth value is taken from the dynamic access control list table, both for a new join request and for pre-existing groups. (R, W, set-by-create) (optional) (1 byte) + +**Multicast service package table:** This attribute is a list that specifies one or more multicast service packages. When the ONU receives an IGMP/MLD join request, it searches the multicast service package table in row key order, matching the VID (UNI) field (several rows can share the same VID). For each VID (UNI) match, the multicast operations profile pointer is used to access the ME that contains the attributes associated with the service package. The search stops when all requested multicast groups have been found and dealt with. + +Each list entry is a vector of six components as follow. + +###### – **Table control** (2 bytes) + +The first 2 bytes of each entry contain a key into the table. It is the responsibility of the OLT to assign and track table keys and content. Since row keys are created by the OLT, they may be densely or sparsely packed. + +The two MSBs of this field determine the meaning of a set operation. These bits are returned as 00 during get next operations. + +| Bits 16..15 | Meaning | +|-------------|--------------------------------------------------------------------------------------| +| 00 | Reserved | +| 01 | Write this entry into the table. Overwrite any existing entry with the same row key. | +| 10 | Delete this entry from the table. The remaining fields are not meaningful. | +| 11 | Clear all entries from the table. The remaining fields are not meaningful. | + +Bits 14..11 are reserved. Bits 10..1 are the row key itself. + +###### – **VID (UNI).** The value in this field is compared with the VID of upstream IGMP/MLD messages, and is used to decide whether to honour a join request. (2 bytes) + +Values: + +0..4095 – Matched against the VID of the IGMP/MLD message. 0 indicates a priority-tagged message, whose P bits are ignored. + +4096 – Matches untagged IGMP/MLD messages only. + +4097 – Matches tagged messages only, but ignores the value of the VID. + +0xFFFF – Unspecified. + +The VID (UNI) comparison occurs prior to any action defined by the upstream IGMP tag control attribute in an associated multicast operations profile (or alternatively, before any modification by a possible (extended) VLAN tagging operation configuration data ME). + +- **Max simultaneous groups.** This field specifies the maximum number of dynamic multicast groups that may be replicated to the client port at any one time, for the multicast service package that is associated with this row. The value 0 specifies that no administrative limit is to be imposed. (2 bytes) + - **Max multicast bandwidth.** This field specifies the maximum imputed dynamic bandwidth, in bytes per second, that may be delivered to the client port at any one time, for the multicast service package that is associated with this row. The value 0 specifies that no administrative limit is to be imposed. (4 bytes) +- NOTE – The port is also constrained by the global max simultaneous groups and max multicast bandwidth attributes of the multicast subscriber config info ME. +- **Multicast operations profile pointer.** This field contains the ME ID of the multicast operations profile ME associated with this service package. (2 bytes) + - **Reserved** (8 bytes) + +(R, W) (optional) (20*N* bytes, where *N* is the number of entries in the table) + +**Allowed preview groups table:** This attribute is a list that specifies the preview groups that are currently allowed for the UNI associated with this ME. It is intended to support paid viewing of a multicast group that may or may not have been previewed. + +When an IGMP/MLD join request is received, the order of search precedence is as follows. + +1. Multicast operations profile(s), fully authorized groups +2. This attribute, the allowed preview groups table +3. Multicast operations profile(s), preview-only groups + +If the first match is a group listed in this attribute, the ONU forwards the group to the UNI until the group is removed from this list or until the subscriber leaves the group. + +Each list entry begins with a table control field: + +##### **Table control (2 bytes)** + +| | | | | | | | | | | | | | | | | +|----------|----|----------|----|----|-----|----|---------|---|---|---|---|---|---|---|---| +| 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| Set ctrl | | Row part | | | Rsv | | Row key | | | | | | | | | + +The first 2 bytes of each entry contain a key into the table, as well as table management fields. It is the responsibility of the OLT to assign and track row keys and content. + +##### Set ctrl + +The two MSBs of this field determine the meaning of a set operation. These bits are returned as 00 during get next operations. + +| Bits 16..15 | Meaning | +|-------------|-----------------------------------------------------------------------------------------------------| +| 00 | Reserved | +| 01 | Write this entry into the table. Overwrite any existing entry with the same row part and row key. | +| 10 | Delete this entry from the table, including all row parts. The remaining fields are not meaningful. | +| 11 | Clear all entries from the table. The remaining fields are not meaningful. | + +##### Row part + +The row part field allows the table to contain logical rows that exceed the maximum length of a single row. Table entries with the same row key and different row parts are understood to comprise a single extended row. In this ME, an extended row always contains two row parts. + +The meaning of extended rows is defined as follows. + +| Bits 14..12 | Meaning | +|-------------|---------------------------------------------| +| 000 | The associated row operation is for part 0. | +| 001 | The associated row operation is for part 1. | +| 010..111 | Reserved | + +##### Rsv + +This bit is reserved. + +##### Row key + +The row key identifies rows in the table. Row keys may be either densely or sparsely populated. + +##### Row part format definition + +| Byte | Row part 0 | Row part 1 | +|------|---------------------------------|-----------------------------------------| +| 1 | Table control
(2 bytes) | Table control
(2 bytes) | +| 2 | | | +| 3 | Source IP address
(16 bytes) | Destination IP
address
(16 bytes) | +| 4 | | | +| 5 | | | +| 6 | | | +| 7 | | | +| 8 | | | + +| Byte | Row part 0 | Row part 1 | +|------|----------------------------|------------------------| +| 9 | | | +| 10 | | | +| 11 | | | +| 12 | | | +| 13 | | | +| 14 | | | +| 15 | | | +| 16 | | | +| 17 | | | +| 18 | | | +| 19 | VLAN ID (ANI)
(2 bytes) | Duration
(2 bytes) | +| 20 | | | +| 21 | VLAN ID (UNI)
(2 bytes) | Time left
(2 bytes) | +| 22 | | | + +**Figure 9.3.28-1 – Allowed preview groups row part formats** + +###### **Row part 0 format:** + +- Table control (2 bytes) +- Source IP address. This field specifies the source IP address of the allowed preview group. May be either an IPv4 address (first 12 bytes 0) or an IPv6 address. (16 bytes) +- VLAN ID (ANI). This field specifies the VLAN carrying the multicast group downstream. The VLAN ID resides in the 12 LSBs; the remaining bits are set to 0 and not used. The value 0 designates an untagged downstream flow. (2 bytes) +- VLAN ID (UNI). This field specifies the VLAN carrying IGMP/MLD messages upstream across the UNI. The VLAN ID resides in the 12 LSBs; the remaining bits are set to 0 and not used. The value 0 designates an untagged upstream flow. (2 bytes) + +###### **Row part 1 format:** + +- Table control (2 bytes) +- Destination IP address. This field specifies the destination IP address of the allowed preview group. May be either an IPv4 address (first twelve bytes 0) or an IPv6 address. (16 bytes) +- Duration – This field indicates the static length of time in minutes for which the group is authorized. The value 0 designates unlimited authorization. (2 bytes) +- Time left – This field is controlled by the ONU (ignored during a set operation from the OLT). It indicates how much time (measured in minutes) remains in the authorization. The ONU counts down; when this field reaches zero, the ONU deletes the entire entry from the table and stops replicating the group to the UNI. If the duration field specifies unlimited authorization, this field is ignored. The OLT may extend (or even truncate) the authorization by writing a new value into the + +duration field; the difference between new and old duration values is added to the time left field. (2 bytes) + +(R, W) (optional) (Each row part: 22 bytes) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.3.29 Multicast subscriber monitor** + +This ME provides the current status of each port with respect to its multicast subscriptions. It may be useful for status monitoring or debugging purposes. The status table includes all dynamic groups currently subscribed by the port. + +#### *Relationships* + +Instances of this ME are created and deleted at the request of the OLT. One instance may exist for each IEEE 802.1 UNI configured to support multicast subscription. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data or IEEE 802.1p mapper ME. (R, set-by-create) (mandatory) (2 bytes) + +**ME type:** This attribute indicates the type of the ME implicitly linked by the ME ID attribute. + +0 MAC bridge port config data + +1 IEEE 802.1p mapper service profile + +(R, W, set-by-create) (mandatory) (1 byte) + +**Current multicast bandwidth:** This attribute is the ONU's (BE) estimate of the actual bandwidth currently being delivered to this particular MAC bridge port over all dynamic multicast groups. (R) (optional) (4 bytes) + +**Join messages counter:** This attribute counts the number of times the corresponding subscriber sent a join message that was accepted. When full, the counter rolls over to 0. (R) (optional) (4 bytes) + +**Bandwidth exceeded counter:** This attribute counts the number of join messages that did exceed, or would have exceeded, the max multicast bandwidth, whether accepted or denied. When full, the counter rolls over to 0. (R) (optional) (4 bytes) + +**IPv4 active group list table:** This attribute lists the groups from one of the related dynamic access control list tables or the allowed preview groups table that are currently being actively forwarded, along with the actual bandwidth of each. If a join has been recognized from more than one IPv4 source address for a given group + +on this UNI, there will be one table entry for each. Each table entry has the following form. + +- VLAN ID, 0 if not used (2 bytes) +- Source IP address, 0.0.0.0 if not used (4 bytes) +- Multicast destination IP address (4 bytes) +- Best efforts actual bandwidth estimate, bytes per second (4 bytes) +- Client (set-top box) IP address, i.e., the IP address of the device currently joined (4 bytes) +- Time since the most recent join of this client to the IP channel, in seconds (4 bytes) +- Reserved (2 bytes) + +(R) (mandatory) (24N bytes) + +**IPv6 active group list table:** This attribute lists the groups from one of the related dynamic access control list tables or the allowed preview groups table that are currently being actively forwarded, along with the actual bandwidth of each. If a join has been recognized from more than one IPv6 source address for a given group on this UNI, there will be one table entry for each. In mixed IPv4-IPv6 scenarios, it is possible that some fields might be IPv4, in which case their 12 most significant bytes of the given field are set to zero. Each table entry has the form: + +- VLAN ID, 0 if not used (2 bytes) +- Source IP address, 0 if not used (16 bytes) +- Multicast destination IP address (16 bytes) +- Best efforts actual bandwidth estimate, bytes per second (4 bytes) +- Client (set-top box) IP address, i.e., the IP address of the device currently joined (16 bytes) +- Time since the most recent join of this client to the IP channel, in seconds (4 bytes) + +(R) (optional) (58N bytes) + +#### *Actions* + +Create, delete, get, get next, set + +#### *Notifications* + +None. + +### **9.3.30 Ethernet frame performance monitoring history data upstream** + +This ME collects PM data associated with upstream Ethernet frame delivery. It is based on the Etherstats group of [IETF RFC 2819]. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +NOTE 1 – Implementers are encouraged to consider the Ethernet frame extended PM ME defined in clause 9.3.32, which collects the same counters in a more generalized way. + +#### *Relationships* + +An instance of this ME is associated with an instance of a MAC bridge port configuration data. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a MAC bridge port configuration data. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Drop events:** The total number of events in which packets were dropped due to a lack of resources. This is not necessarily the number of packets dropped; it is the number of times this event was detected. (R) (mandatory) (4 bytes) + +**Octets:** The total number of upstream octets received, including those in bad packets, excluding framing bits, but including FCS. (R) (mandatory) (4 bytes) + +**Packets:** The total number of upstream packets received, including bad packets, broadcast packets and multicast packets. (R) (mandatory) (4 bytes) + +**Broadcast packets:** The total number of upstream good packets received that were directed to the broadcast address. This does not include multicast packets. (R) (mandatory) (4 bytes) + +**Multicast packets:** The total number of upstream good packets received that were directed to a multicast address. This does not include broadcast packets. (R) (mandatory) (4 bytes) + +**CRC errored packets:** The total number of upstream packets received that had a length (excluding framing bits, but including FCS octets) of between 64 octets and 1518 octets, inclusive, but had either a bad FCS with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). (R) (mandatory) (4 bytes) + +**Undersize packets:** The total number of upstream packets received that were less than 64 octets long, but were otherwise well formed (excluding framing bits, but including FCS). (R) (mandatory) (4 bytes) + +**Oversize packets:** The total number of upstream packets received that were longer than 1518 octets (excluding framing bits, but including FCS) and were otherwise well formed. (R) (mandatory) (4 bytes) + +NOTE 2 – If 2 000 byte Ethernet frames are supported, counts in this performance parameter are not necessarily errors. + +**Packets 64 octets:** The total number of upstream received packets (including bad packets) that were 64 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +**Packets 65 to 127 octets:** The total number of upstream received packets (including bad packets) that were 65..127 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +**Packets 128 to 255 octets:** The total number of upstream packets (including bad packets) received that were 128..255 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +**Packets 256 to 511 octets:** The total number of upstream packets (including bad packets) received that were 256..511 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +**Packets 512 to 1023 octets:** The total number of upstream packets (including bad packets) received that were 512..1 023 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +**Packets 1024 to 1518 octets:** The total number of upstream packets (including bad packets) received that were 1024..1518 octets long, excluding framing bits, but including FCS. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold data counter No. (Note) | +|----------------------------------------------------------------------------------------------------------------------------|--------------------------|-----------------------------------| +| 0 | Drop events | 1 | +| 1 | CRC errored packets | 2 | +| 2 | Undersize packets | 3 | +| 3 | Oversize packets | 4 | +| NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. | | | + +### **9.3.31 Ethernet frame performance monitoring history data downstream** + +This ME is identical to the Ethernet frame PM history data upstream ME, with the exception that it monitors downstream traffic. + +### **9.3.32 Ethernet frame extended PM** + +This ME collects some of the PM data at a point where an Ethernet flow can be observed. It is based on the Etherstats group of [IETF RFC 2819]. Instances of this ME are created and deleted by the OLT. References to received frames are to be interpreted as the number of frames entering the monitoring point in the direction specified by the control block. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME may be associated with an instance of an ME at any Ethernet interface within the ONU. The specific ME is identified in the control block attribute. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. To facilitate discovery, the identification of instances sequentially starting with 1 is encouraged. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. If continuous accumulation is enabled in the control block, this attribute is not used and has the fixed value 0. (R) (mandatory) (1 byte) + +**Control Block:** This attribute contains fields defined as follows.+ + +**Threshold data 1/2 ID:** (2 bytes) This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. When PM is collected on a continuously running basis, rather than in 15 min intervals, counter thresholds should not be established. There is no mechanism to clear a TCA, and any counter parameter may eventually be expected to cross any given threshold value. + +**Parent ME class:** (2 bytes) This field contains the enumerated value of the ME class of the PM ME's parent. Together with the parent ME instance field, this permits a given PM ME to be associated with any OMCI ME. The supported ME classes are as follows. + +- 46 MAC bridge configuration data +- 47 MAC bridge port configuration data +- 11 Physical path termination point Ethernet UNI +- 98 Physical path termination point xDSL UNI part 1 +- 266 GEM IW termination point +- 281 Multicast GEM IW termination point +- 329 Virtual Ethernet interface point +- 162 Physical path termination point MoCA UNI + +**Parent ME instance:** (2 bytes) This field identifies the specific parent ME instance to which the PM ME is attached. + +**Accumulation disable:** (2 bytes) This bit field allows PM accumulation to be disabled; refer to Table 9.3.32-1. The default value 0 enables PM collection. If bit 15 is set to 1, no PM is collected by this ME instance. If bit 15 = 0 and any of bits 14..1 are set to 1, PM collection is inhibited for the attributes indicated by the 1 bits. Inhibiting PM collection does not change the value of a PM attribute, but if PM is accumulated in 15 min intervals, the value is lost at the next 15 min interval boundary. + +Bit 16 is an action bit that always reads back as 0. When written to 1, it resets all PM attributes in the ME, and clears any TCAs that may be outstanding. + +**Table 9.3.32-1 – Bit assignments in extended PM control block** + +| Bit | 16 | 15 | 14 | 13 | 3 | 2 | 1
(LSB) | +|-----------------------------|--------------|----------------|------|-----|-----|-----|------------| +| Accumulation disable | Global clear | Global disable | PM14 | ... | ... | PM2 | PM1 | +| TCA disable | | Global disable | Th14 | ... | ... | Th2 | Th1 | + +**TCA disable:** (2 bytes). Also clarified in Table 9.3.32-1, this field permits TCAs to be inhibited, either individually or for the complete ME instance. As with the accumulation disable field, the default value 0 enables TCAs, and setting the global disable bit overrides the settings of the individual thresholds. Unlike the accumulation disable field, the bits are mapped to the thresholds defined in the associated threshold data 1 and 2 ME instances. When the global or attribute-specific value changes from 0 to 1, outstanding TCAs are cleared, either for the ME instance globally or for the individual disabled threshold. These bits affect only notifications, not the underlying parameter accumulation or storage. + +If the threshold data 1/2 ID attribute does not contain a valid pointer, this field is not meaningful. + +Thresholds should be used with caution if PM attributes are accumulated continuously. + +**Control fields:** (2 bytes). This field is a bit map whose values govern the behaviour of the PM ME. Bits are assigned as follows. + +- | | | +|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Bit 1 (LSB) | The value 1 specifies continuous accumulation, regardless of 15 min intervals. There is no concept of current and historical accumulators; get and get current data (if supported) both return current values. The value 0 specifies 15 min accumulators exactly like those of classical PM. | +| Bit 2 | This bit indicates directionality for the collection of data. The value 0 indicates that data are to be collected for upstream traffic. The value 1 indicates that data are to be collected for downstream traffic. | +| Bits 3..14 | Reserved, should be set to 0 by the OLT and ignored by the ONU. | +| Bit 15 | When this bit is 1, the P bits of the TCI field are used to filter the PM data collected. The value 0 indicates that PM is collected without regard to P bits. | +| Bit 16 | When this bit is 1, the VID bits of the TCI field are used to filter the PM data collected. The value 0 indicates that PM is collected without regard to VID. | + +**TCI:** (2 bytes). This field contains the value optionally used as a filter for the PM data collected, under the control of bits 15..16 of the control fields. This value is matched to the outer tag of a frame. Untagged frames are not counted when this field is used. + +**Reserved:** (2 bytes). Not used; should be set to 0 by the OLT and ignored by the ONU. + +(R, W, set-by-create) (mandatory) (16 bytes) + +**Drop events:** The total number of events in which frames were dropped due to a lack of resources. This is not necessarily the number of frames dropped; it is the number of times this event was detected. (R) (mandatory) (4 bytes) + +**Octets:** The total number of octets received, including those in bad frames, excluding framing bits, but including FCS. (R) (mandatory) (4 bytes) + +**Frames:** The total number of frames received, including bad frames, broadcast frames and multicast frames. (R) (mandatory) (4 bytes) + +**Broadcast frames:** The total number of received good frames directed to the broadcast address. This does not include multicast frames. (R) (mandatory) (4 bytes) + +**Multicast frames:** The total number of received good frames directed to a multicast address. This does not include broadcast frames. (R) (mandatory) (4 bytes) + +**CRC errored frames:** The total number of frames received that had a length (excluding framing bits, but including FCS octets) of between 64 and 1518 octets, inclusive, but had either a bad FCS with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). (R) (mandatory) (4 bytes) + +- Undersize frames:** The total number of frames received that were less than 64 octets long but were otherwise well formed (excluding framing bits, but including FCS octets). (R) (mandatory) (4 bytes) +- Oversize frames:** The total number of frames received that were longer than 1518 octets (excluding framing bits, but including FCS octets) and were otherwise well formed. (R) (mandatory) (4 bytes) +- Frames 64 octets:** The total number of received frames (including bad frames) that were 64 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Frames 65 to 127 octets:** The total number of received frames (including bad frames) that were 65..127 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Frames 128 to 255 octets:** The total number of frames (including bad frames) received that were 128..255 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Frames 256 to 511 octets:** The total number of frames (including bad frames) received that were 256..511 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Frames 512 to 1 023 octets:** The total number of frames (including bad frames) received that were 512..1 023 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Frames 1024 to 1518 octets:** The total number of frames (including bad frames) received that were 1024..1518 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold data counter No. (Note) | +|--------------|--------------------------|-----------------------------------| +| 1 | Drop events | 1 | +| 2 | CRC errored frames | 2 | +| 3 | Undersize frames | 3 | +| 4 | Oversize frames | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.3.33 MAC bridge port ICMPv6 process pre-assign table** + +This ME provides an approach to ICMPv6 message processing configuration to those ONUs that support IPv6 awareness. For every message, the MAC bridge port ICMPv6 process pre-assign table can designate a forward, discard or snoop operation. The ONU creates or deletes an instance of this ME automatically upon creation or deletion of a MAC bridge port configuration data ME. + +The MAC bridge port ICMPv6 process pre-assign table ME filters layer 2 traffic between the UNI and ANI. The operation of this ME is completely independent of the operation and traffic generated or received by a possible IPv6 host config data ME. + +#### Relationships + +An instance of this ME is associated with an instance of a MAC bridge port configuration data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the MAC bridge port configuration data ME. (R) (mandatory) (2 bytes) + +The following nine attributes have similar definitions. Each permits the OLT to specify ICMPv6 as the next header in the IPv6 header and various types in the ICMPv6 header, and whether traffic of the specified type is forwarded, discarded or snooped, in upstream and downstream directions separately. The bits of each attribute are assigned as follows. + +| Bit | Name | Setting | +|------------|------------------------|-----------------------------------------| +| 1..2 (LSB) | Process for upstream | 00: forward
01: discard
10: snoop | +| 3..4 | Process for downstream | 00: forward
01: discard
10: snoop | +| 5..8 | Reserved | 0 | + +The initial value of each attribute is given in the last column of the table. + +| No. | Protocol | Next header | type | Standard | Initial value | +|-----|-----------------------------------------------|-------------|---------|----------------------------------------|---------------| +| 1 | ICMPv6 error messages | 58 | 1-4 | [b-IETF RFC 2460]
[b-IETF RFC 2463] | 0 | +| 2 | ICMPv6 informational messages | 58 | 128,129 | [b-IETF RFC 2460]
[b-IETF RFC 2463] | 0 | +| 3 | Neighbour discovery router solicitation | 58 | 133 | [b-IETF RFC 2460]
[b-IETF RFC 4861] | 6 | +| 4 | Neighbour discovery – router advertisement | 58 | 134 | [b-IETF RFC 2460]
[b-IETF RFC 4861] | 9 | +| 5 | Neighbour discovery – neighbour solicitation | 58 | 135 | [b-IETF RFC 2460]
[b-IETF RFC 4861] | 0 | +| 6 | Neighbour discovery – neighbour advertisement | 58 | 136 | [b-IETF RFC 2460]
[b-IETF RFC 4861] | 0 | +| 7 | Neighbour discovery – redirect | 58 | 137 | [b-IETF RFC 2460]
[b-IETF RFC 4861] | 1 | + +| No. | Protocol | Next header | type | Standard | Initial value | +|-----|-----------------------------------------------|-------------|------|--------------------------------------|---------------| +| 8 | MLD – Multicast listener query (MLDv1, MLDv2) | 58 | 130 | [b-IETF RFC 2710]
[IETF RFC 3810] | 1 | +| 9 | Unknown ICMPv6 | 58 | – | – | 5 | + +**ICMPv6 error messages processing:** (R, W) (mandatory) (1 byte) + +**ICMPv6 informational messages processing:** (R, W) (mandatory) (1 byte) + +**Router solicitation processing:** (R, W) (mandatory) (1 byte) + +**Router advertisement processing:** (R, W) (mandatory) (1 byte) + +**Neighbour solicitation processing:** (R, W) (mandatory) (1 byte) + +**Neighbour advertisement processing:** (R, W) (mandatory) (1 byte) + +**Redirect processing:** (R, W) (mandatory) (1 byte) + +**Multicast listener query processing:** (R, W) (mandatory) (1 byte) + +NOTE – If the ONU participates in multicast services, MLD queries should be controlled through the multicast operations profile ME. In such a case, it is strongly recommended not to provision the downstream direction of the multicast listener query processing attribute to any value other than forwarding. + +**Unknown ICMPv6 processing:** (R, W) (mandatory) (1 byte) + +#### *Actions* + +Get, set. + +### **9.3.34 Ethernet frame extended PM 64 bit** + +This ME collects some of the PM data at a point where an Ethernet flow can be observed. It is based on the Etherstats group of [IETF RFC 2819] and [IETF RFC 2863]. Instances of this ME are created and deleted by the OLT. References to received frames are to be interpreted as the number of frames entering the monitoring point in the direction specified by the control block. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME may be associated with an instance of an ME at any Ethernet interface within the ONU. The specific ME is identified in the control block attribute. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. To facilitate discovery, it is encouraged to identify instances sequentially starting with 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. If continuous accumulation is enabled in the control block, this attribute is not used and has the fixed value 0. (R) (mandatory) (1 byte) + +**Control block:** This attribute contains fields defined as follows. + +**Threshold data 64 bit ID:** (2 bytes). This attribute points to an instance of the threshold data 64-bit ME that contains PM threshold values. When PM is collected on a continuously running basis, rather than in 15 min intervals, counter thresholds should not be established. There is no mechanism to clear + +a TCA, and any counter parameter may eventually be expected to cross any given threshold value. + +**Parent ME class:** (2 bytes). This field contains the enumerated value of the ME class of the PM ME's parent. Together with the parent ME instance field, this permits a given PM ME to be associated with any OMCI ME. The supported ME classes are as follows. + +- 46 MAC bridge configuration data +- 47 MAC bridge port configuration data +- 11 Physical path termination point Ethernet UNI +- 98 Physical path termination point xDSL UNI part 1 +- 266 GEM IW termination point +- 281 Multicast GEM IW termination point +- 329 Virtual Ethernet interface point +- 162 Physical path termination point MoCA UNI + +**Parent ME instance:** (2 bytes). This field identifies the specific parent ME instance to which the PM ME is attached. + +**Accumulation disable:** (2 bytes). This bit field allows PM accumulation to be disabled; refer to Table 9.3.32-1. The default value 0 enables PM collection. If bit 15 is set to 1, no PM is collected by this ME instance. If bit 15 = 0 and any of bits 14..1 are set to 1, PM collection is inhibited for the attributes indicated by the 1 bits. Inhibiting PM collection does not change the value of a PM attribute, but if PM is accumulated in 15 min intervals, the value is lost at the next 15 min interval boundary. + +Bit 16 is an action bit that always reads back as 0. When written to 1, it resets all PM attributes in the ME, and clears any TCAs that may be outstanding. + +**TCA disable:** (2 bytes). Also clarified in Table 9.3.32-1, this field permits TCAs to be inhibited, either individually or for the complete ME instance. As with the accumulation disable field, the default value 0 enables TCAs, and setting the global disable bit overrides the settings of the individual thresholds. Unlike the accumulation disable field, the bits are mapped to the thresholds defined in the associated threshold data 1 and 2 ME instances. When the global or attribute-specific value changes from 0 to 1, outstanding TCAs are cleared, either for the ME instance globally or for the individual disabled threshold. These bits affect only notifications, not the underlying parameter accumulation or storage. + +If the threshold data 64 bit ID attribute does not contain a valid pointer, this field is not meaningful. + +Thresholds should be used with caution if PM attributes are accumulated continuously. + +**Control fields:** (2 bytes). This field is a bit map whose values govern the behaviour of the PM ME. Bits are assigned as follows: + +- Bit 1 (LSB) The value 1 specifies continuous accumulation, regardless of 15 min intervals. There is no concept of current and historic accumulators; get and get current data (if supported) both return current values. The value 0 specifies 15 min accumulators exactly like those of classical PM. +- Bit 2 This bit indicates directionality for the collection of data. The value 0 indicates that data are to be collected for + +| | | +|------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | upstream traffic. The value 1 indicates that data are to be collected for downstream traffic. | +| Bits 3..14 | Reserved, should be set to 0 by the OLT and ignored by the ONU. | +| Bit 15 | When this bit is 1, the P bits of the TCI field are used to filter the PM data collected. The value 0 indicates that PM is collected without regard to P bits. | +| Bit 16 | When this bit is 1, the VID bits of the TCI field are used to filter the PM data collected. The value 0 indicates that PM is collected without regard to VID. | + +**TCI:** (2 bytes). This field contains the value optionally used as a filter for the PM data collected, under the control of bits 15..16 of the control fields. This value is matched to the outer tag of a frame. Untagged frames are not counted when this field is used. + +**Reserved:** (2 bytes). Not used; should be set to 0 by the OLT and ignored by the ONU. + +(R, W, set-by-create) (mandatory) (16 bytes) + +**Drop events:** The total number of events in which frames were dropped due to lack of resources. This is not necessarily the number of frames dropped; it is the number of times this event was detected. (R) (mandatory) (8 bytes) + +**Octets:** The total number of octets received, including those in bad frames, excluding framing bits, but including FCS. (R) (mandatory) (8 bytes) + +**Frames:** The total number of frames received, including bad frames, broadcast frames and multicast frames. (R) (mandatory) (8 bytes) + +**Broadcast frames:** The total number of received good frames directed to the broadcast address. This does not include multicast frames. (R) (mandatory) (8 bytes) + +**Multicast frames:** The total number of received good frames directed to a multicast address. This does not include broadcast frames. (R) (mandatory) (8 bytes) + +**CRC errored frames:** The total number of frames received that had a length (excluding framing bits, but including FCS octets) of between 64 and 1518 octets, inclusive, but had either a bad FCS with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). (R) (mandatory) (8 bytes) + +**Undersize frames:** The total number of frames received that were less than 64 octets long, but were otherwise well formed (excluding framing bits, but including FCS octets). (R) (mandatory) (8 bytes) + +**Oversize frames:** The total number of frames received that were longer than 1518 octets (excluding framing bits, but including FCS octets) and were otherwise well formed. (R) (mandatory) (8 bytes) + +**Frames 64 octets:** The total number of received frames (including bad frames) that were 64 octets long, excluding framing bits, but including FCS. (R) (mandatory) (8 bytes) + +**Frames 65 to 127 octets:** The total number of received frames (including bad frames) that were 65..127 octets long, excluding framing bits but including FCS. (R) (mandatory) (8 bytes) + +**Frames 128 to 255 octets:** The total number of frames (including bad frames) received that were 128..255 octets long, excluding framing bits but including FCS. (R) (mandatory) (8 bytes) + +**Frames 256 to 511 octets:** The total number of frames (including bad frames) received that were 256..511 octets long, excluding framing bits but including FCS. (R) (mandatory) (8 bytes) + +**Frames 512 to 1023 octets:** The total number of frames (including bad frames) received that were 512..1023 octets long, excluding framing bits but including FCS. (R) (mandatory) (8 bytes) + +**Frames 1024 to 1518 octets:** The total number of frames (including bad frames) received that were 1024..1518 octets long, excluding framing bits but including FCS. (R) (mandatory) (8 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold data counter No. (Note) | +|--------------|--------------------------|-----------------------------------| +| 1 | Drop events | 1 | +| 2 | CRC errored frames | 2 | +| 3 | Undersize frames | 3 | +| 4 | Oversize frames | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the "threshold data 64 bit" managed entity (see clause 9.12.17). + +### **9.3.35 Link aggregation service profile** + +This ME organizes data associated with a link aggregation group (LAG) in PON channel bonding. The OLT creates one instance of this managed entity for each channel bonding LAG. + +#### *Relationships* + +One instance of this managed entity exists for each LAG. An instance of this managed entity is associated with one or more instances of MAC bridge port configuration data. An instance of this managed entity is associated with one instances of MAC bridge service profile. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this managed entity. Its value is created by the OLT. (R, set-by-create) (mandatory) (2 bytes) + +**Frame distribution and collection mode:** This attribute indicates the frame distribution and collection mode supported on this LAG. Valid values are: + +- 1 Per-service frame distribution. This mode distributes frames to the bonded links according to their service identifier. The algorithm is specified in IEEE 802.1AX clause 8. +- 2 Round-robin frame distribution. This mode distributes frames to the bonded links in circular order. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Type:** This attribute indicates the LASP ME type. Valid values are: + 0 ANI-G interface channel bonding. + 1 UNI-G interface channel bonding. + (R, W, Set-by-create) (mandatory) (1 byte) + +**MAC bridge service profile ID pointer:** This attribute points to an instance of the MAC bridge service profile ME. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +## **9.4 Layer 3 data services** + +### **9.4.1 IP host config data** + +The IP host config data configures IPv4 based services offered on the ONU. The ONU automatically creates instances of this ME if IP host services are available. A possible IPv6 stack is supported through the IPv6 host config data ME. In this clause, references to IP addresses are understood to mean IPv4. + +#### *Relationships* + +An instance of this ME is associated with the ONU ME. Any number of TCP/UDP config data MEs can point to the IP host config data, to model any number of ports and protocols. Performance may be monitored through an implicitly linked IP host PM history data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The ONU creates as many instances as there are independent IPv4 stacks on the ONU. To facilitate discovery, IP host config data MEs should be numbered from 0 upwards. The ONU should create IP(v4) and IPv6 host config data MEs with separate ME IDs, such that other MEs can use a single TP type attribute to link with either. (R) (mandatory) (2 bytes) + +**IP options:** This attribute is a bit map that enables or disables IP-related options. The value 1 enables the option while 0 disables it. The default value of this attribute is 0. + +| | | +|------------|--------------------------------| +| 0x01 | Enable DHCP | +| 0x02 | Respond to pings | +| 0x04 | Respond to traceroute messages | +| 0x08 | Enable IP stack | +| 0x10..0x80 | Reserved | + +(R, W) (mandatory) (1 byte) + +**MAC address:** This attribute indicates the MAC address used by the IP node. (R) (mandatory) (6 bytes) + +**Onu identifier:** A unique ONU identifier string. If set to a non-null value, this string is used instead of the MAC address in retrieving dynamic host configuration protocol (DHCP) parameters. If the string is shorter than 25 characters, it must be null terminated. Its default value is 25 null bytes. (R, W) (mandatory) (25 bytes) + +Several attributes of this ME may be paired together into two categories, manual settings and current values. + +| Manual settings | Current values | +|-----------------|-----------------------| +| IP address | Current address | +| Mask | Current mask | +| Gateway | Current gateway | +| Primary DNS | Current primary DNS | +| Secondary DNS | Current secondary DNS | + +While the IP stack is disabled, there is no IP connectivity to the external world from this ME instance. While DHCP is disabled, the current values are always the same as the manual settings. While DHCP is enabled, the current values are those assigned by DHCP, or undefined (0) if DHCP has never assigned values. + +**IP address:** The address used for IP host services; this attribute has the default value 0. (R, W) (mandatory) (4 bytes) + +**Mask:** The subnet mask for IP host services; this attribute has the default value 0. (R, W) (mandatory) (4 bytes) + +**Gateway:** The default gateway address used for IP host services; this attribute has the default value 0. (R, W) (mandatory) (4 bytes) + +**Primary DNS:** The address of the primary DNS server; this attribute has the default value 0. (R, W) (mandatory) (4 bytes) + +**Secondary DNS:** The address of the secondary DNS server; this attribute has the default value 0. (R, W) (mandatory) (4 bytes) + +**Current address:** Current address of the IP host service. (R) (optional) (4 bytes) + +**Current mask:** Current subnet mask for the IP host service. (R) (optional) (4 bytes) + +**Current gateway:** Current default gateway address for the IP host service. (R) (optional) (4 bytes) + +**Current primary DNS:** Current primary DNS server address. (R) (optional) (4 bytes) + +**Current secondary DNS:** Current secondary DNS server address. (R) (optional) (4 bytes) + +**Domain name:** If DHCP indicates a domain name, it is presented here. If no domain name is indicated, this attribute is set to a null string. If the string is shorter than 25 bytes, it must be null terminated. The default value is 25 null bytes. (R) (mandatory) (25 bytes) + +**Host name:** If DHCP indicates a host name, it is presented here. If no host name is indicated, this attribute is set to a null string. If the string is shorter than 25 bytes, it must be null terminated. The default value is 25 null bytes. (R) (mandatory) (25 bytes) + +**Relay agent options:** This attribute is a pointer to a large string ME whose content specifies one or more DHCP relay agent options. (R, W) (optional) (2 bytes) + +The contents of the large string are parsed by the ONU and converted into text strings. Variable substitution is based on defined three-character groups, each of which begins with the '%' character. The string '%%' is an escape mechanism whose output is a single '%' character. When the ONU cannot perform variable substitution on a substring of the large string, it generates the specified option as an exact quotation of the provisioned substring value. + +Provisioning of the large string is separate from the operation of setting the pointer in this attribute. It is the responsibility of the OLT to ensure that the large string contents are correct and meaningful. + +Three-character variable definitions are as follows. The first variable in the large string must specify one of the option types. Both options for a given IP version may be present if desired, each introduced by its option identifier. Terminology is taken from clause 3.9.3 of [b-BBF TR-101]. + +%01, %18 + +Specifies that the following string is for option 82 sub-option 1, agent circuit-ID (IPv4) or option 18, interface-ID (IPv6). The equivalence permits the same large string to be used in both IP environments. + +%02, %37 + +Specifies that the following string is for option 82 sub-option 2, relay agent remote-ID (IPv4) or option 37, relay agent remote-ID (IPv6). The equivalence permits the same large string to be used in both IP environments. + +%SL In [b-BBF TR-101], this is called a slot. In an ONU, this variable refers to a shelf. It would be meaningful if the ONU has multiple shelves internally or is daisy-chained to multiple equipment modules. The range of this variable is "0".. "99" + +%SU In TR-101, this is called a sub-slot. In fact, it represents a cardholder. The range of this variable is "0".. "99" + +%PO UNI port number. The range of this variable is "0".. "999" + +%AE ATM or Ethernet. This variable can take on the values "atm" or "eth". + +%SV S-VID for Ethernet UNI, or ATM virtual path identifier (VPI) for ATM UNI, as it exists on the DHCP request received upstream across the UNI. Range "0".. "4096" for S-VID; range "0".. "255" for VPI. The value "4096" indicates no S-VID tag. + +%CV C-VID (Q-VID) for Ethernet UNI, or ATM virtual circuit identifier (VCI) for ATM UNI, as it exists on the DHCP request received upstream across the UNI. Range "0".. "4096" for C-VID; range "0".. "65535" for VCI. The value "4096" indicates no C-VID tag. + +Spaces in the provisioned string are significant. + +Example: if the large string were provisioned with the value + +%01%SL/%SU/%PO:%AE/%SV.%CV, + +then the ONU would generate the following DHCP option 82 agent circuit-ID string for an Ethernet UNI that sent a DHCP request with no S tag and C tag = 3210 on shelf 2, slot 3, port 4. + +2/3/4:eth/4096.3210 + +With the same provisioning, the ONU would generate the following DHCP option 82 agent circuit-ID string for an ATM UNI that sent a DHCP request on VPI = 123 and VCI = 4567 on shelf 2, slot 3, port 4. + +2/3/4:atm/123.4567 + +#### Actions + +Get, set + +Test: Invoke an Internet control message protocol (ICMP) message from this IP host. The test message can be configured to generate a ping or traceroute. Annex A defines the test, test response and test result messages. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------| +| 1..8 | N/A | | +| 9 | Current address | The new value assigned via DHCP | +| 10 | Current mask | The new value assigned via DHCP | +| 11 | Current gateway | The new value assigned via DHCP | +| 12 | Current primary DNS | The new value assigned via DHCP | +| 13 | Current secondary DNS | The new value assigned via DHCP | +| 14 | Domain name | The new value assigned via DHCP | +| 15 | Host name | The new value assigned via DHCP | +| 16 | Reserved | | + +### 9.4.2 IP host performance monitoring history data + +This ME collects PM data related to an IP host. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of the IP host config data or IPv6 host config data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the IP host configuration data or IPv6 host configuration data ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**ICMP errors:** This attribute counts ICMP errors received. (R) (mandatory) (4 bytes) + +**DNS errors:** This attribute counts DNS errors received. (R) (mandatory) (4 bytes) + +**DHCP timeouts:** This attribute counts DHCP timeouts. (R) (optional) (2 bytes) + +**IP address conflict:** This attribute is incremented whenever the ONU detects a conflicting IP address on the network. A conflicting IP address is one that has the same value as the one currently assigned to the ONU. (R) (optional) (2 bytes) + +**Out of memory:** This attribute is incremented whenever the ONU encounters an out of memory condition in the IP stack. (R) (optional) (2 bytes) + +**Internal error:** This attribute is incremented whenever the ONU encounters an internal error condition such as a driver interface failure in the IP stack. (R) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 1 | IPNPM ICMP error | 1 | +| 2 | IPNPM DNS error | 2 | +| 3 | DHCP timeout | 3 | +| 4 | IP address conflict | 4 | +| 5 | Out of memory | 5 | +| 6 | Internal error | 6 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.4.3 TCP/UDP config data** + +The TCP/UDP config data ME configures services based on the transmission control protocol (TCP) and user datagram protocol (UDP) that are offered from an IP host. If a non-OMCI interface is used to manage an IP service, this ME is unnecessary; the non-OMCI interface supplies the necessary data. + +An instance of this ME is created and deleted on request of the OLT. + +#### *Relationships* + +One or more instances of this ME may be associated with an instance of an IP host config data or IPv6 host config data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. It is recommended that the ME ID be the same as the port number. (R, set-by-create) (mandatory) (2 bytes) + +**Port ID:** This attribute specifies the port number that offers the TCP/UDP service. (R, W, set-by-create) (mandatory) (2 bytes) + +**Protocol:** This attribute specifies the protocol type as defined by [b-IANA] (protocol numbers), for example UDP (0x11). (R, W, set-by-create) (mandatory) (1 byte) + +**TOS/diffserv field:** This attribute specifies the value of the TOS/diffserv field of the IPv4 header. The contents of this attribute may contain the type of service per [IETF RFC 2474] or a DSCP. Valid values for DSCP are as defined by [b-IANA] (differentiated services field code points). (R, W, set-by-create) (mandatory) (1 byte) + +**IP host pointer:** This attribute points to the IP host config data or IPv6 host config data ME associated with this TCP/UDP data. Any number of ports and protocols may be associated with an IP host. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.4.4 TCP/UDP performance monitoring history data** + +This ME collects PM data related to a TCP or UDP port. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the TCP/UDP config data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TCP/UDP config data ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Socket failed:** This attribute is incremented when an attempt to create a socket associated with a port fails. (R) (mandatory) (2 bytes) + +**Listen failed:** This attribute is incremented when an attempt by a service to listen for a request on a port fails. (R) (mandatory) (2 bytes) + +**Bind failed:** This attribute is incremented when an attempt by a service to bind to a port fails. (R) (mandatory) (2 bytes) + +**Accept failed:** This attribute is incremented when an attempt to accept a connection on a port fails. (R) (mandatory) (2 bytes) + +**Select failed:** This attribute is incremented when an attempt to perform a *select* on a group of ports fails. (R) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | N/A | | +| 1 | Socket failed | 1 | +| 2 | Listen failed | 2 | +| 3 | Bind failed | 3 | +| 4 | Accept failed | 4 | +| 5 | Select failed | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.4.5 IPv6 host config data + +The IPv6 host config data configures IPv6 based services offered on the ONU. The ONU automatically creates instances of this ME if IPv6 host services are available. If an IPv4 stack is present, it is independently supported through the IP host config data ME. + +This ME may be statically provisioned or may derive its parameters from router advertisements (RAs) or DHCPv6. + +#### Relationships + +One or more instances of this ME are associated with the ONU ME. Any number of TCP/UDP config data MEs can point to the IPv6 host config data, to model any number of ports and protocols. Performance may be monitored through an implicitly linked IP host PM history data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The ONU creates as many instances as there are independent IP stacks on the ONU. To facilitate discovery, IP and IPv6 host config data MEs should be numbered from 0 upwards. The ONU must create IP(v4) and IPv6 host config data MEs with separate ME IDs, such that other MEs can use a single TP type attribute to link with either. (R) (mandatory) (2 bytes) + +**IP options:** This attribute is a bit map that enables or disables IPv6 related options. The value 1 enables the option, while 0 disables it. The default value of this attribute is 0. (R, W) (mandatory) (1 byte) + +0x01 IPv6 stack administrative unlock. + +0x02 Enable router solicitation (RS). The host generates RS messages, if necessary, and responds to RAs. If the RA message has the M flag set to 1, the ONU is expected to request the address and other configuration information via DHCPv6. If the RA message has the O flag set to 1 and M to 0, the ONU is expected to only request additional configuration information via DHCPv6, but not addresses. + +0x04 Enable DHCPv6. + +0x08 Respond to pings (ICMPv6 echo replies) + +0x10..0x80 Reserved + +The following IP stack initialization flow is expected. + +1. If the IPv6 stack is administratively unlocked (0x01), establish a link-local address [self-assign address, duplicate address detection (DAD) to confirm that address is unique within the local link]. This process is defined in [b-IETF RFC 4862], and is a part of stateless address autoconfiguration (SLAAC). However, no IP options are set to enable or disable this function – it always happens. +2. If RS and DHCPv6 are both disabled, do nothing. Manual settings are to be used and are required for this IPv6 stack to be fully functional. +3. If RS is enabled (0x02) and DHCPv6 is disabled, send RS and listen for an RA. If no RA is received, the ONU never attempts DHCPv6 and cannot complete automated initialization of IPv6. If an RA is received then the following occur. + - a. The ONU builds its default router table per [b-IETF RFC 4861], reported via the current default router table attribute. + - b. If the received RA includes information option(s) with an "A" prefix, then ONU assigns itself an address from all such A prefixes, per [b-IETF RFC 4862] (also part of SLAAC) (reported via the current address table attribute). + - c. If the received RA includes DNS information [b-IETF RFC 6106], the ONU accepts it (reported via the current DNS table attribute). Support for RFC 6106 is strongly recommended. + - d. If the received RA has M = 1, then the ONU requests identity association for non-temporary addresses (IA\_NA) and other options (which could include DNS) via DHCPv6. The access network provider is responsible for ensuring that, if it sends DNS information both in the RA and DHCPv6, it sends the same DNS information; it must not rely on the ONU to figure out whether RA DNS is preferred over DHCPv6 DNS or *vice versa*. If different DNS information is received via DHCPv6, it also goes into the current DNS table attribute. If the ONU gets IA\_NA via DHCPv6, this goes into the current address table attribute. + - e. If the received RA has M = 0 and O = 1, then the ONU requests stateless options (which could include DNS) via DHCPv6. +4. If RS and DHCPv6 are both enabled, the ONU does RS (as described in a-c above, if RA is received) and DHCPv6 (requesting IA\_NA and other options, as described in d above) simultaneously, effectively ignoring M and O flags. +5. If RS is disabled and DHCPv6 is enabled, then the ONU does not send RS and it does send DHCPv6 (requesting IA\_NA and other options, as described in d above). If an unsolicited RA is received, it is ignored. + +**MAC address:** This attribute indicates the MAC address used by the IP node. (R) (mandatory) (6 bytes) + +**Onu identifier:** A unique ONU identifier string. If set to a non-null value, this string is used instead of the MAC address in retrieving DHCPv6 parameters. If the string is shorter than 25 characters, it must be null terminated. Its default value is 25 null bytes. (R, W) (mandatory) (25 bytes) + +Several attributes of this ME may be paired together into two categories, manual settings and current values. + +| Manual settings | Current values | +|-----------------|------------------------------| +| IPv6 address | Current address table | +| Default router | Current default router table | +| Primary DNS | Current DNS table | +| Secondary DNS | | +| On-link prefix | Current on-link prefix table | + +While this ME instance is administratively locked, it provides no IPv6 connectivity to the external world. Especially if manual provisioning is to be used, it is important that the ME remain locked until provisioning is complete. + +While autoconfiguration is disabled, the current values are the same as the manual settings. While autoconfiguration is enabled, the current values are those autoconfigured on the basis of RAs, assigned by DHCPv6, or undefined (empty tables) if no values have (yet) been assigned. + +**IPv6 link local address:** The address used for on-link IP host services, such as RS and DHCPv6. [b-IETF RFC 4862] specifies how to automatically establish a link-local address. (R) (mandatory) (16 bytes) + +**IPv6 address:** The manually provisioned IPv6 address used for routed IPv6 host services. The address remains valid until reprovisioned, i.e., the preferred and valid lifetimes of this address are infinite. The default value of this attribute is the undefined address 0. (R, W) (mandatory) (16 bytes) + +**Default router:** The manually provisioned IPv6 address of the default router. The default value of this attribute is the undefined address 0. (R, W) (mandatory) (16 bytes) + +**Primary DNS:** The manually provisioned IPv6 address of the primary DNS server. The default value of this attribute is the undefined address 0. (R, W) (mandatory) (16 bytes) + +**Secondary DNS:** The manually provisioned IPv6 address of the secondary DNS server. The default value of this attribute is the undefined address 0. (R, W) (mandatory) (16 bytes) + +**Current address table:** This attribute is a list of the current IPv6 addresses of the IP host service. The link-local address does not appear in this table. Each row of the table is structured as follows. + +IP address (16 bytes) + +Preferred lifetime remaining, seconds (4 bytes) + +Valid lifetime remaining, seconds (4 bytes) + +If the manually provisioned IPv6 address attribute appears as the (only, by necessity) entry of the table, its preferred and valid lifetimes are infinite (0xFFFF FFFF). + +(R) (mandatory) (24*N* bytes) + +**Current default router table:** This attribute lists the IPv6 addresses of the current default routers. (R) (mandatory) (16*N* bytes) + +**Current DNS table:** This attribute lists the IPv6 addresses of the current DNS servers. (R) (mandatory) (16*N* bytes) + +**Dynamic host configuration protocol unique identifier (DUID):** This attribute is the DHCPv6 unique identifier. It is an octet string that must be globally unique and must remain stable over the lifetime of the ONU. If the string is shorter than 25 bytes, it must be null terminated. Its derivation is beyond the scope of this Recommendation; see [b-IETF RFC 3315] for further definition. (R) (mandatory) (25 bytes) + +**On-link prefix:** This attribute is the manually provisioned on-link prefix used for destination IPv6 addresses of IPv6 host services. The attribute is structured as follows. +    Prefix length, number of leading bits in the prefix that are valid (1 byte) +    Prefix (16 bytes) +(R,W) (optional) (17 bytes) + +**Current on-link prefix table:** In IPv6, an address is on a specific link if the address has been assigned to an interface attached to that link. However, in order for a node to know that a destination is on-link, it must obtain configuration information to that effect. A host maintains a prefix list that identifies ranges of addresses that are to be considered on-link ([b-IETF RFC 5942]). This attribute is a list of current on-link prefixes used for destination IPv6 addresses of IPv6 host services. Entries in this table come from RA messages received by the ONU from remote routers or manually provisioned to be on-link. Each row of the table is structured as follows. + +    Prefix length, number of leading bits in the prefix that are valid (1 byte) +    Autonomous address-configuration flag byte. When set to 1, it indicates that this prefix can be used for stateless address configuration as specified in [b-IETF RFC 4862]; otherwise 0. (1 byte) +    Prefix (16 bytes) +    Preferred lifetime, seconds (4 bytes) +    Valid lifetime, seconds (4 bytes) + +If the manually provisioned on-link prefix attribute is present in the current on-link prefix table, its preferred and valid lifetimes are infinite (0xFFFF FFFF), and its autonomous address-configuration flag is 0. + +(R) (optional) (26*N* bytes) + +**Relay agent options:** This attribute is a pointer to a large string ME whose content specifies one or more DHCP relay agent options. (R, W) (optional) (2 bytes) + +The meaning and interpretation of the large string's contents are identical to that described in the IP host config data definition in clause 9.4.1. + +#### *Actions* + +Get, get next, set + +Test:            Invoke an ICMP message from this IP host. The test message can be configured to generate a ping or traceroute. Annex A defines the test, test response and test result messages. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1..8 | N/A | | +| 9 | Current address table | AVC generated when a new address is added to the table, or when an existing address becomes invalid and is removed from the table. Countdown of the lifetime fields does not generate AVCs. | +| 10 | Current default router table | | +| 11 | Current DNS table | | +| 12..13 | N/A | | +| 14 | Current on-link prefix table | | +| 15..16 | Reserved | | + +### 9.4.6 IP host performance monitoring history data part 2 + +This managed entity collects additional performance monitoring data related to an IP host, related in particular to the DHCP server access errors. Instances of this managed entity are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this managed entity is associated with an instance of the IP host config data or IPv6 host config data managed entity. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this managed entity. Through an identical ID, this managed entity is implicitly linked to an instance of the IP host configuration data or IPv6 host configuration data ME, as well as to the corresponding IP host PMHD ME (135). (R, Set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15-minute interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 managed entity that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, Set-by-create) (mandatory) (2 bytes) + +**DHCP Attempts count:** This attribute counts the number of DHCP discover request. (R) (mandatory) (4 bytes) + +**DHCP Acks received count:** This attribute counts the number of successful DHCP attempt (number of times the ONT DHCP client obtained a lease). (R) (mandatory) (4 bytes) + +**DHCP Nacks count:** This attribute counts the number of Negative acknowledgements (NACKS) received for requests. Number of times the ONT's DHCP Client was denied a lease. (R) (mandatory) (4 bytes) + +**DHCP response error count:** This attribute is incremented whenever the ONU receives a malformed/badly formatted response from the DHCP server. (R) (mandatory) (2 bytes) + +**DHCP response incomplete count:** This attribute is incremented whenever the DHCP server response does not contain all the parameters required to successfully set up the IP configuration. (R) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | DHCP response error | 1 | +| 1 | DHCP response incomplete | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +## **9.5 Ethernet services** + +This clause defines the MEs associated with physical and virtual Ethernet UNIs, as shown in Figure 9.5-1. + +![Diagram showing managed entities associated with Ethernet UNIs. It includes 9.5.5: Virtual Ethernet interface point, 9.5.1: PPTP Ethernet UNI, 9.5.6: PoE control, 9.5.4: Ethernet PM history data 3, 9.5.2: Ethernet PM history data, and 9.5.3: Ethernet PM history data 2. Arrows indicate implicit links and pointing relationships between these entities.](52f7a3277fa444ec8818ec7328aa498e_img.jpg) + +The diagram illustrates the relationships between various managed entities (MEs) for Ethernet services. At the center is the **9.5.1: PPTP Ethernet UNI**. Above it is the **9.5.5: Virtual Ethernet interface point**. To the left, under the heading **Implicit links:**, are **Extended VLAN tagging operation config data** (pointing to 9.5.5) and **802.1p mapper service profile MAC bridge port config data (Extended) VLAN tagging operation config data** (pointing to 9.5.1). To the right, under **Points to:**, is **TCP/UDP config data** (pointing to 9.5.5). Below 9.5.1 are **9.5.6: PoE control** and **9.5.4: Ethernet PM history data 3**, both pointing to 9.5.1. To the right of 9.5.1 are **9.5.2: Ethernet PM history data** and **9.5.3: Ethernet PM history data 2**, both pointing to 9.5.1. Dashed arrows indicate other implicit links between 9.5.5, 9.5.1, 9.5.2, 9.5.3, and 9.5.4. + +Diagram showing managed entities associated with Ethernet UNIs. It includes 9.5.5: Virtual Ethernet interface point, 9.5.1: PPTP Ethernet UNI, 9.5.6: PoE control, 9.5.4: Ethernet PM history data 3, 9.5.2: Ethernet PM history data, and 9.5.3: Ethernet PM history data 2. Arrows indicate implicit links and pointing relationships between these entities. + +G.988(12)\_F9.5-1 + +**Figure 9.5-1 – Managed entities associated with Ethernet UNIs** + +### **9.5.1 Physical path termination point Ethernet UNI** + +This ME represents the point at an Ethernet UNI where the physical path terminates and Ethernet physical level functions are performed. + +The ONU automatically creates an instance of this ME per port: + +- when the ONU has Ethernet ports built into its factory configuration; +- when a cardholder is provisioned to expect a circuit pack of the Ethernet type; +- when a cardholder provisioned for plug-and-play is equipped with a circuit pack of the Ethernet type. Note that the installation of a plug-and-play card may indicate the presence of Ethernet ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies Ethernet ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect an Ethernet circuit pack, nor is it equipped with an Ethernet circuit pack. + +#### Relationships + +An instance of this ME is associated with each instance of a pre-provisioned or real Ethernet port. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +**Expected type:** This attribute supports pre-provisioning. It is coded as follows: + +| | | +|----------|---------------------------------------------------------------------------------------| +| 0 | Autosense | +| 1 to 254 | One of the values from Table 9.1.5-1 that is compatible with an Ethernet circuit pack | + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +**Sensed type:** When a circuit pack is present, this attribute represents its type as one of the values from Table 9.1.5-1. If the value of the expected type is not 0, then the value of the sensed type should be the same as the value of the expected type. Upon ME instantiation, the ONU sets this attribute to 0. See also the note in the following AVC table. + +(R) (mandatory if the ONU supports circuit packs with configurable interface types, e.g., 10/100 BASE-T card) (1 byte) + +**Auto detection configuration:** This attribute sets the following Ethernet port configuration. + +| Code point | Rate | Duplex | +|------------|------------------|------------------| +| 0x00 | Auto | Auto | +| 0x01 | 10 Mbit/s only | Full duplex only | +| 0x02 | 100 Mbit/s only | Full duplex only | +| 0x03 | 1000 Mbit/s only | Full duplex only | +| 0x04 | Auto | Full duplex only | +| 0x05 | 10Gb/s only | Full duplex only | +| 0x06 | 2.5Gb/s only | Full duplex only | +| 0x07 | 5Gb/s only | Full duplex only | +| 0x08 | 25Gb/s only | Full duplex only | +| 0x09 | 40Gb/s only | Full duplex only | +| 0x10 | 10 Mbit/s only | Auto | +| 0x11 | 10 Mbit/s only | Half duplex only | +| 0x12 | 100 Mbit/s only | Half duplex only | +| 0x13 | 1000 Mbit/s only | Half duplex only | +| 0x14 | Auto | Half duplex only | + +| Code point | Rate | Duplex | +|------------|------------------|--------| +| 0x20 | 1000 Mbit/s only | Auto | +| 0x30 | 100 Mbit/s only | Auto | + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory for interfaces with autodetection options) (1 byte) + +**Ethernet loopback configuration:** This attribute sets the following Ethernet loopback configuration. + +- 0 No loopback +- 3 Loop 3, loopback of downstream traffic after PHY transceiver. Loop 3 is depicted in Figure 9.5.1-1. + +Note that normal bridge behaviour may defeat the loopback signal unless broadcast MAC addresses are used. Although it does not reach the physical interface, [IEEE 802.1ag] loopback is preferred. + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +![Diagram of Ethernet loopback configuration. An ONU box contains a PHY transceiver. An 'Ethernet UNI' line enters the PHY from the left. A curved arrow labeled 'Loopback 3' originates from the output of the PHY and loops back to its input. The PHY has an output line on the right that connects to a 'PON' (Passive Optical Network) represented by a circle with three lines radiating from it. The text 'G.988(12)_F9.5.1-1' is in the bottom right corner.](d36508ae73a5197d96f5c0773261515a_img.jpg) + +Diagram of Ethernet loopback configuration. An ONU box contains a PHY transceiver. An 'Ethernet UNI' line enters the PHY from the left. A curved arrow labeled 'Loopback 3' originates from the output of the PHY and loops back to its input. The PHY has an output line on the right that connects to a 'PON' (Passive Optical Network) represented by a circle with three lines radiating from it. The text 'G.988(12)\_F9.5.1-1' is in the bottom right corner. + +**Figure 9.5.1-1 – Ethernet loopback configuration** + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Configuration ind:** This attribute indicates the configuration status of the Ethernet UNI. + +- 0x01 10BASE-T full duplex +- 0x02 100BASE-T full duplex +- 0x03 Gigabit Ethernet full duplex +- 0x04 10Gb/s Ethernet full duplex +- 0x05 2.5Gb/s Ethernet full duplex +- 0x06 5Gb/s Ethernet full duplex +- 0x07 25Gb/s Ethernet full duplex +- 0x08 40Gb/s Ethernet full duplex +- 0x11 10BASE-T half duplex +- 0x12 100BASE-T half duplex +- 0x13 Gigabit Ethernet half duplex + +The value 0 indicates that the configuration status is unknown (e.g., Ethernet link is not established or the circuit pack is not yet installed). Upon ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (1 byte) + +**Max frame size:** This attribute denotes the maximum frame size allowed across this interface. Upon ME instantiation, the ONU sets the attribute to 1518. (R, W) (mandatory for G-PON, optional for ITU-T G.986 systems) (2 bytes) + +**DTE or DCE ind:** This attribute specifies the following Ethernet interface wiring. + +- 0 DCE or MDI-X (default). +- 1 DTE or MDI. +- 2 Automatic selection + +(R, W) (mandatory) (1 byte) + +**Pause time:** This attribute allows the PPTP to ask the subscriber terminal to temporarily suspend sending data. Units are in pause quanta (1 pause quantum is 512 bit times of the particular implementation). Values: 0..0xFFFF. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (2 bytes) + +**Bridged or IP ind:** This attribute specifies whether the Ethernet interface is bridged or derived from an IP router function. + +- 0 Bridged +- 1 IP router +- 2 Depends on the parent circuit pack. 2 means that the circuit pack's bridged or IP ind attribute is either 0 or 1. + +Upon ME instantiation, the ONU sets this attribute to 2. (R, W) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**PPPoE filter:** This attribute controls filtering of PPPoE packets on this Ethernet port. The value 0 allows packets of all types. The value 1 discards everything but PPPoE packets. The default value is 0. (R, W) (optional) (1 byte) + +**Power control:** This attribute controls whether power is provided to an external equipment over the Ethernet PPTP. The value 1 enables power over the Ethernet port. The default value 0 disables power feed. (R, W) (optional) (1 byte) + +NOTE – This attribute is the equivalent of the acPSEAdminControl variable defined in clause 30.9.1.2.1 of [IEEE 802.3]. Other variables related to PoE appear in the PoE control ME. + +**Disable packet-based time synchronization:** This attribute controls the packet based time synchronization provided to an external equipment over the Ethernet PPtP (for ONUs capable of supporting packet-based time synchronization through the Precision Time Protocol ME and/or Synchronous Ethernet ME). Bits are assigned as follows: + +- Bit 1 (LSB) PTP Disable – synchronization via PTP protocol is disabled with a value of 1 or enabled with a value of 0. +- Bit 2 SynchE Disable – synchronization via SynchE is disabled with a value of 1 or enabled with a value of 0. +- Bit 3..16 Reserved + +The default value of all bits is 0 (packet-based time synchronization is enabled) when ONU supports packet synchronization. + +NOTE – ONUs that are not capable of packet-based time synchronization should not instantiate this attribute. In the event that packet-based time synchronization is supported, but a particular combination is not supported, the default or set value that is not applicable will be ignored by the ONU. For example, if PTP is supported but not SynchE, the default enabled SynchE value will be ignored by the ONU. Likewise, any attempt to enable or disable not supported values (e.g., in previous example SyncE) will be ignored. + +(R, W) (optional) (1 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | N/A | | +| 2 | Sensed type | Sensed type of Ethernet interface. Valid values are as follows.
1 (10BASE-T)
2 (100BASE-T)
3 (Gigabit Ethernet)
4 (10G Ethernet).
(Note) | +| 3..5 | N/A | | +| 6 | Op state | Operational state | +| 7..11 | N/A | | +| 12 | ARC | ARC timer expiration | +| 13..15 | N/A | | +| 16 | Reserved | | + +NOTE – These values violate the rules of the AVC message, which require the changed value of the sensed type (in this case) attribute to be reported. Because of existing implementations, pre-existing documentation is retained; however, implementers should regard this attribute and its AVC with caution. + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|------------------------|--------------------------------| +| 0 | LAN-LOS | No carrier at the Ethernet UNI | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.5.2 Ethernet performance monitoring history data** + +This ME collects some of the PM data for a physical Ethernet interface. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the PPTP Ethernet UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP Ethernet UNI. (R, set-by-create) (mandatory) (2 bytes) + +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) +- FCS errors:** This attribute counts frames received on a particular interface that were an integral number of octets in length but failed the FCS check. The count is incremented when the MAC service returns the frameCheckError status to the link layer control (LLC) or other MAC user. Received frames for which multiple error conditions are obtained are counted according to the error status presented to the LLC. (R) (mandatory) (4 bytes) +- Excessive collision counter:** This attribute counts frames whose transmission failed due to excessive collisions. (R) (mandatory) (4 bytes) +- Late collision counter:** This attribute counts the number of times that a collision was detected later than 512 bit times into the transmission of a packet. (R) (mandatory) (4 bytes) +- Frames too long:** This attribute counts received frames that exceeded the maximum permitted frame size. The count is incremented when the MAC service returns the frameTooLong status to the LLC. (R) (mandatory) (4 bytes) +- Buffer overflows on receive:** This attribute counts the number of times that the receive buffer overflowed. (R) (mandatory) (4 bytes) +- Buffer overflows on transmit:** This attribute counts the number of times that the transmit buffer overflowed. (R) (mandatory) (4 bytes) +- Single collision frame counter:** This attribute counts successfully transmitted frames whose transmission was delayed by exactly one collision. (R) (mandatory) (4 bytes) +- Multiple collisions frame counter:** This attribute counts successfully transmitted frames whose transmission was delayed by more than one collision. (R) (mandatory) (4 bytes) +- SQE counter:** This attribute counts the number of times that the SQE test error message was generated by the PLS sublayer. (R) (mandatory) (4 bytes) +- Deferred transmission counter:** This attribute counts frames whose first transmission attempt was delayed because the medium was busy. The count does not include frames involved in collisions. (R) (mandatory) (4 bytes) +- Internal MAC transmit error counter:** This attribute counts frames whose transmission failed due to an internal MAC sublayer transmit error. (R) (mandatory) (4 bytes) +- Carrier sense error counter:** This attribute counts the number of times that carrier sense was lost or never asserted when attempting to transmit a frame. (R) (mandatory) (4 bytes) +- Alignment error counter:** This attribute counts received frames that were not an integral number of octets in length and did not pass the FCS check. (R) (mandatory) (4 bytes) +- Internal MAC receive error counter:** This attribute counts frames whose reception failed due to an internal MAC sublayer receive error. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-------------------------------------|--------------------------------------| +| 0 | FCS errors | 1 | +| 1 | Excessive collision counter | 2 | +| 2 | Late collision counter | 3 | +| 3 | Frames too long | 4 | +| 4 | Buffer overflows on receive | 5 | +| 5 | Buffer overflows on transmit | 6 | +| 6 | Single collision frame counter | 7 | +| 7 | Multiple collisions frame counter | 8 | +| 8 | SQE counter | 9 | +| 9 | Deferred transmission counter | 10 | +| 10 | Internal MAC transmit error counter | 11 | +| 11 | Carrier sense error counter | 12 | +| 12 | Alignment error counter | 13 | +| 13 | Internal MAC receive error counter | 14 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.5.3 Ethernet performance monitoring history data 2 + +This ME collects additional PM data for a physical Ethernet interface. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this Ethernet PM history data 2 ME is associated with an instance of the PPTP Ethernet UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP Ethernet UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**PPPoE filtered frame counter:** This attribute counts the number of frames discarded due to PPPoE filtering. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|------------------------------|--------------------------------------| +| 0 | PPPoE filtered frame counter | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.5.4 Ethernet performance monitoring history data 3 + +This ME collects PM data associated with an Ethernet interface. It includes parameters defined in the Ethernet statistics group of [IETF RFC 2819] that are not already covered by previously defined Ethernet monitoring MEs. The received direction is from the CPE towards the network (upstream). + +NOTE 1 – Several of the same counters are available from the Ethernet frame PM history data MEs, which are associated with MAC bridge ports. MAC bridge port association allows those MEs to be used for any Ethernet flow, in both upstream and downstream directions, while the Ethernet PM history data 3 ME can only be used on a physical IEEE 802.3 port. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +NOTE 2 – Implementers are encouraged to consider the Ethernet frame extended PM ME defined in clause 9.3.32, which collects the same counters in a more generalized way. + +#### Relationships + +An instance of this ME is associated with an instance of the PPTP Ethernet UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP Ethernet UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Drop events:** The total number of events in which packets were dropped due to a lack of resources. This is not necessarily the number of packets dropped; it is the number of times this event was detected. (R) (mandatory) (4 bytes) + +**Octets:** The total number of octets received from the CPE, including those in bad packets, excluding framing bytes, but including FCS. (R) (mandatory) (4 bytes) + +**Packets:** The total number of packets received, including bad packets, broadcast packets and multicast packets. (R) (mandatory) (4 bytes) + +- Broadcast packets:** The total number of received good packets directed to the broadcast address. This does not include multicast packets. (R) (mandatory) (4 bytes) +- Multicast packets:** The total number of received good packets directed to a multicast address. This does not include broadcast packets. (R) (mandatory) (4 bytes) +- Undersize packets:** The total number of packets received that were less than 64 octets long, but were otherwise well formed (excluding framing bits, but including FCS). (R) (mandatory) (4 bytes) +- Fragments:** The total number of packets received that were less than 64 octets long, excluding framing bits but including FCS octets, and had either a bad FCS with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). It is entirely normal for this attribute to increment. This is because it counts both runts (which are normal occurrences due to collisions) and noise hits. (R) (mandatory) (4 bytes) +- Jabbers:** The total number of packets received that were longer than 1518 octets, excluding framing bits but including FCS octets, and had either a bad FCS with an integral number of octets (FCS error) or a bad FCS with a non-integral number of octets (alignment error). The range to detect jabber is between 20 ms and 150 ms. (R) (mandatory) (4 bytes) +- Packets 64 octets:** The total number of received packets (including bad packets) that were 64 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Packets 65 to 127 octets:** The total number of received packets (including bad packets) that were 65..127 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Packets 128 to 255 octets:** The total number of packets (including bad packets) received that were 128..255 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Packets 256 to 511 octets:** The total number of packets (including bad packets) received that were 256..511 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Packets 512 to 1023 octets:** The total number of packets (including bad packets) received that were 512..1023 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) +- Packets 1024 to 1518 octets:** The total number of packets (including bad packets) received that were 1024..1518 octets long, excluding framing bits but including FCS. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +| Threshold crossing alert | | | +|--------------------------|--------------------------|-----------------------------------| +| Alarm number | Threshold crossing alert | Threshold data counter No. (Note) | +| 0 | Drop events | 1 | +| 1 | Undersize packets | 2 | +| 2 | Fragments | 3 | +| 3 | Jabbers | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.5.5 Virtual Ethernet interface point + +This ME represents the data plane hand-off point in an ONU to a separate (non-OMCI) management domain. The VEIP is managed by the OMCI, and is potentially known to the non-OMCI management domain. One or more Ethernet traffic flows are present at this boundary. + +Instances of this ME are automatically created and deleted by the ONU. This is necessary because the required downstream priority queues are subject to physical implementation constraints. The OLT may use one or more of the VEIPs created by the ONU. + +It is expected that the ONU will create one VEIP for each non-OMCI management domain. At the vendor's discretion, a VEIP may be created for each traffic class. + +#### Relationships + +An instance of this ME is associated with an instance of a virtual Ethernet interface between OMCI and non-OMCI management domains. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. When used independently of a cardholder and circuit pack, the ONU should assign IDs in the sequence 1, 2, .... When used in conjunction with a cardholder and circuit pack, this 2 byte number indicates the physical position of the VEIP. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. The values 0 and 0xFFFF are reserved. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Interdomain name:** This attribute is a character string that provides an optional way to identify the VEIP to a non-OMCI management domain. The interface may also be identified by its ME ID, [b-IANA] assigned port and possibly other ways. If the vendor offers no information in this attribute, it should be set to a sequence of null bytes. (R, W) (optional) (25 bytes) + +**TCP/UDP pointer:** This attribute points to an instance of the TCP/UDP config data ME, which provides for OMCI management of the non-OMCI management domain's IP connectivity. If no OMCI management of the non-OMCI domain's + +IP connectivity is required, this attribute may be omitted or set to its default, a null pointer. (R, W) (optional) (2 bytes) + +**IANA assigned port:** This attribute contains the TCP or UDP port value as assigned by [b-IANA] for the management protocol associated with this virtual Ethernet interface. This attribute is to be regarded as a hint, not as a requirement that management communications use this port; the actual port and protocol are specified in the associated TCP/UDP config data ME. If no port has been assigned or if the management protocol is free to be chosen at run-time, this attribute should be set to 0xFFFF. (R) (mandatory) (2 bytes) + +NOTE – This attribute does not apply to USP management protocol. For USP MTP discovery, please refer to clause 9.12.19. + +#### *Actions* + +Get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------| +| 0..1 | N/A | | +| 2 | Op state | Operational state | +| 3 | N/A | | +| 4..16 | Reserved | | + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|--------------------------|---------------------------------------------------------------------------------------------------------------------------------| +| 0 | Connecting function fail | Indicates a failure of the connecting function. May be used to signal faults from the non-OMCI management domain into the OMCI. | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.5.6 Power over Ethernet control** + +This ME represents the ability to monitor and control the PoE capability of the ONU as power-sourcing equipment (PSE) as defined in clauses 30.9 and 33 of [IEEE 802.3]. + +An ONU that supports the enhanced PoE control feature automatically creates or deletes an instance of this ME whenever it creates or deletes the corresponding PTP Ethernet UNI. + +Administrative control of the PoE feature resides in the power control attribute of the PTP Ethernet UNI ME. + +#### *Relationships* + +An instance of this ME is associated with each instance of a PTP Ethernet UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the physical path Ethernet UNI ME. (R) (mandatory) (2 bytes) + +**PoE capabilities:** This attribute is a bit map that identifies the PoE capabilities of the port. + +Bits are assigned as follows. + +| Bit | Meaning | +|---------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 (LSB) | When this bit is 1, the PSE pinout alternative may be changed through the power pair pinout control attribute. When the bit is 0, the PSE pinout alternative is fixed, and is described by the power pair pinout control attribute. | +| 2..16 | Reserved | + +(R) (mandatory) (2 bytes) + +**Power pair pinout control:** If the PSE pinout is configurable, according to the PoE capabilities attribute, this attribute is used to configure the pinout. If the PSE pinout is fixed, this attribute is read-only. In either case, the value returned by a get operation indicates the actual configuration. The value 0 configures/indicates pinout alternative A (signal pairs); the value 1 configures/indicates pinout alternative B (spare pairs). Other values are reserved. This attribute corresponds to the aPSEPowerPairs variable defined in [IEEE 802.3]. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the PPTP is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (mandatory) (1 byte) + +**Power detection status:** This attribute is an enumeration that returns the current status of the port. It corresponds to the aPSEPowerDetectionStatus variable defined in [IEEE 802.3]. Its values are defined as follows. + +| | | +|---|--------------------------------------------| +| 0 | PSE disabled | +| 1 | PSE searching | +| 2 | PSE delivering power | +| 3 | PSE test mode | +| 4 | PSE fault detected | +| 5 | PSE implementation specific fault detected | +| | Other values are reserved. | + +(R) (mandatory) (1 byte) + +**Power classification status:** This attribute is an enumeration that indicates the powered device (PD) class of a detected PD. It is only valid when the power detection status attribute indicates PSE delivering power. The attribute corresponds to the aPSEPowerClassification variable defined in [IEEE 802.3]. Its values are defined as follows. + +| | | +|---|------------------------------------| +| 0 | Undefined or feature not supported | +| 1 | Class 0 PD | +| 2 | Class 1 PD | +| 3 | Class 2 PD | +| 4 | Class 3 PD | +| 5 | Class 4 PD | +| | Other values are reserved. | + +(R) (optional) (1 byte) + +**Power priority:** This attribute controls the priority of the port from the point of view of a power management algorithm. The priority that is set by this attribute could be used by a control mechanism that prevents overcurrent situations by first disconnecting ports with lower power priority (higher numerical value). The + +attribute corresponds to the pethPsePortPowerPriority variable defined in [b-IETF RFC 3621]. Valid values are as follows. + +- 1 critical +- 2 high +- 3 low + +(R, W) (optional) (1 byte) + +**Invalid signature counter:** This attribute increments when the PoE state machine depicted in Figure 33-6 of [IEEE 802.3] enters the signature\_invalid state, but not more than twice per second. The counter is never explicitly reset, but its value is not required to persist over ONU initialization. (R) (optional) (2 bytes) + +**Power denied counter:** This attribute increments when the PoE state machine depicted in Figure 33-6 of [IEEE 802.3] enters the power\_denied state, but not more than twice per second. The counter is never explicitly reset, but its value is not required to persist over ONU initialization. (R) (optional) (2 bytes) + +**Overload counter:** This attribute increments when the PoE state machine depicted in Figure 33-6 of [IEEE 802.3] enters the error\_delay\_over state, but not more than twice per second. The counter is never explicitly reset, but its value is not required to persist over ONU initialization. (R) (optional) (2 bytes) + +**Short counter:** This attribute increments when the PoE state machine depicted in Figure 33-6 of [IEEE 802.3] enters the error\_delay\_short state, but not more than twice per second. The counter is never explicitly reset, but its value is not required to persist over ONU initialization. (R) (optional) (2 bytes) + +**MPS absent counter:** This attribute increments when the PoE state machine depicted in Figure 33-6 of [IEEE 802.3] goes from the state power\_on to the idle state, but not more than twice per second. The counter is never explicitly reset, but its value is not required to persist over ONU initialization. (R) (optional) (2 bytes) + +**PSE class control:** This attribute may be used to place specific limits on the class of power supported by this port. Valid code points for this attribute are as follows. + +- 0 Power feed enabled at the default level for this port +- 1 Power feed enabled at the class 0 power level +- 2 Power feed enabled at the class 1 power level +- 3 Power feed enabled at the class 2 power level +- 4 Power feed enabled at the class 3 power level +- 5 Power feed enabled at the class 4 power level + +Other values are reserved. (R, W) (optional) (1 byte) + +**Current Power Consumption:** This attribute is used to report, in milliwatts, the actual power being provided by this port.. + +(R) (optional) (4 bytes) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-------------| +| 1..2 | N/A | | +| 3 | Operational state | | + +| | | | +|--------|----------|--| +| 4..12 | N/A | | +| 13..16 | Reserved | | + +## 9.6 This clause is intentionally left blank + +## 9.7 xDSL services + +This clause defines MEs associated with physical xDSL UNIs. The MEs relation diagram addressing ADSL (ITU-T G.992 family) and VDSL (ITU-T G.995 family) services is shown in Figure 8.2.4-1. + +This figure is left blank + +###### Figure 9.7-1 – Blank figure + +NOTE 1 – Concerning ADSL and VDSL services, this clause is based on [ITU-T G.997.1]. In comparison to their [ITU-T G.997.1] equivalents, descriptions in this Recommendation frequently appear in condensed or summarized form. To avoid rendering existing implementations non-standard, the OMCI always defines new attributes added to existing MEs to be optional, even though [ITU-T G.997.1] may specify that the new attributes are mandatory. When the OMCI defines a new ME, however, it follows [ITU-T G.997.1]. Furthermore, [ITU-T G.997.1] sometimes calls out different requirements for different xDSL Recommendations, which may or may not be completely captured in clause 9.7. Finally, [ITU-T G.997.1] is itself subject to revision as xDSL standards evolve. + +Users of this Recommendation, when concerned with ADSL or VDSL services, are therefore encouraged to consult the current version of [ITU-T G.997.1] for further details. + +The associated MEs and relation diagram addressing FAST services is shown in Figure 8.2.4-3. The associated MEs are defined based on [ITU-T G.997.2]. + +NOTE 2 – In comparison to their [ITU-T G.997.2] equivalents, descriptions in this Recommendation may appear in condensed or summarized form. To avoid rendering existing implementations non-standard, the OMCI always defines new attributes added to existing MEs to be optional, even though [ITU-T G.997.2] may specify these new attributes as mandatory. When the OMCI defines a new ME, however, it follows [ITU-T G.997.2], which is itself subject to revision as [ITU-T G.9701] evolves. + +Users concerned with FAST services are encouraged to consult the current version of [ITU-T G.997.2] for further details. + +### 9.7.1 Physical path termination point xDSL UNI part 1 + +This ME represents the point where physical paths terminate on an xDSL CO modem (xTU-C). The xDSL ME family1 is used for ADSL VDSL2 and FAST services. A legacy family of VDSL MEs remains valid for ITU-T G.993.1 VDSL, if needed. It is documented in [ITU-T G.983.2]. + +The ONU automatically creates an instance of this ME per port: + +- when the ONU has xDSL ports built into its factory configuration; +- when a cardholder is provisioned to expect a circuit pack of the xDSL type; +- when a cardholder provisioned for plug-and-play is equipped with a circuit pack of the xDSL type. Note that the installation of a plug-and-play card may indicate the presence of xDSL ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies xDSL ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect an xDSL circuit pack, nor is it equipped with an xDSL circuit pack. + +1 The xDSL MEs include the ITU-T G.992 family as well as ITU-T G.993.2 VDSL2, but not ITU-T G.993.1 VDSL. + +#### *Relationships* + +An instance of this ME is associated with each instance of a real or pre-provisioned xDSL port. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The six LSBs of the first byte are the slot ID, defined in clause 9.1.5. The two MSBs indicate the channel number in some of the implicitly linked MEs, and must be 0 in the PPTP itself. This reduces the possible number of physical slots to 64. The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +**Loopback configuration:** This attribute represents the loopback configuration of this physical interface. + +- 0 No loopback +- 1 Loopback2 – a loopback at the ONU towards the OLT. The OLT can execute a physical level loopback test after loopback2 is set. + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**xDSL line configuration profile:** This attribute points to an instance of the xDSL line configuration profiles (part 1, 2 and 3) MEs, and if necessary, also to VDSL2 line configuration extensions (1 and 2) MEs, also to vectoring line configuration extension MEs. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) + +**xDSL subcarrier masking downstream profile:** This attribute points to an instance of the xDSL subcarrier masking downstream profile ME. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) + +**xDSL subcarrier masking upstream profile:** This attribute points to an instance of the xDSL subcarrier masking upstream profile ME. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) + +**xDSL downstream power spectral density (PSD) mask profile:** This attribute points to an instance of the xDSL PSD mask profile ME that defines downstream parameters. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) + +**xDSL downstream RFI bands profile:** This attribute points to an instance of the xDSL downstream RFI bands profile ME. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Modem type:** This attribute specifies the modem type. If the hardware cannot support the requested modem type, the ONU should deny the provisioning command. For backward compatibility, the attribute is optional, with a default of ATM. + +- 0 undefined +- 1 ATM (default) +- 2 PTM (Ethernet) + +(R, W) (optional) (1 byte) + +NOTE – Many newer VDSL2 chip sets support only PTM. The ATM default is retained for backward compatibility, but implementers should be aware that the default may need to be overridden by provisioning before the xDSL UNI can be brought into service. + +**Upstream PSD mask profile:** This attribute points to an instance of the xDSL PSD mask profile that defines upstream parameters. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (optional) (2 bytes) + +**Network specific extensions pointer:** This attribute points to a network address ME that contains the path and name of a file containing network specific parameters for the associated UNI. Upon ME instantiation, the ONU sets this attribute to 0xFFFF, a null pointer. (R, W) (optional) (2 bytes) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------| +| 1..2 | N/A | | +| 3 | Op state | Operational state | +| 4..8 | N/A | | +| 9 | ARC | ARC timer expiration | +| 10..12 | N/A | | +| 13..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|----------|--------------------------------------| +| 0 | NE LOF | Near-end loss of frame | +| 1 | NE LOS | Near-end loss of signal | +| 2 | NE LOL | Near-end loss of link | +| 3 | NE LPR | Near-end loss of power | +| 4 | Card alm | Card in alarm | +| 5 | FE LOF | Far-end loss of frame | +| 6 | FE LOS | Far-end loss of signal | +| 7 | FE LOL | Far-end loss of link | +| 8 | FE LPR | Far-end loss of power | +| 9 | DRT up | Data rate threshold upshift (Note 1) | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|----------------|--------------------------------------------------------------------------------------------------------------| +| 10 | DRT down | Data rate threshold downshift (Note 1) | +| 11 | LINIT | Line initialization failure | +| 12 | LCD | Loss of cell delineation, near end (Note 2) | +| 13 | NCD | No cell delineation, near end (Note 2) | +| 14 | LCD-FE | Loss of cell delineation, far end (Note 2) | +| 15 | NCD-FE | No cell delineation, far end (Note 2) | +| 16 | File not found | The PPTP xDSL UNI attempted to access a network specific extensions file that is not available. | +| 17 | OOS | PTM near-end out-of-sync failure – see clause 7.1.5.1.1 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3] | +| 18 | OOS-FE | PTM far-end out-of-sync failure - see clause 7.1.5.2.1 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3] | +| 19 | LOR | Loss-of-RMC (LOR) failure – see clause 7.4.1.2 of [ITU-T G.997.2] | +| 20 | LOM | Loss-of-margin (LOM) failure – see clause 7.4.1.3 of [ITU-T G.997.2] | +| 21 | LOR-FE | Far-end loss-of-RMC (LOR-FE) failure – see clause 7.4.2.2 of [ITU-T G.997.2] | +| 22 | LOM-FE | Far-end loss-of-margin (LOM-FE) failure – see clause 7.4.2.3 of [ITU-T G.997.2] | +| 23.207 | Reserved | | + +NOTE 1 – The data rate upshift and downshift alarms are deprecated. They are not defined in [ITU-T G.997.1]. + +NOTE 2 – These alarms are meaningful only for ATM transport. The alarms may be declared against the UNI itself, or against one of the bearer channels. In the latter case, the two MSBs of the instance identifier in the alarm message specify the bearer channel. + +### 9.7.2 Physical path termination point xDSL UNI part 2 + +This ME represents the point in the ONU where physical paths terminate on an xDSL CO modem (xTU-C). Standards and chip sets support several forms of DSL, including VDSL2, and the xDSL ME family is used for all of them, with specific extensions for technology variations. + +The ONU creates or deletes an instance of this ME at the same time it creates or deletes the corresponding PPTP xDSL UNI part 1. + +#### Relationships + +An instance of this ME is associated with each instance of a PPTP xDSL UNI part 1. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +Each of the following eight attributes is a pointer to an xDSL channel configuration profile ME. In each case, the default value 0, set when the ME is auto-created, is a null pointer. + +- xDSL channel configuration profile for bearer channel 0 downstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 1 downstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 2 downstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 3 downstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 0 upstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 1 upstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 2 upstream:** +(R, W) (optional) (2 bytes) +- xDSL channel configuration profile for bearer channel 3 upstream:** +(R, W) (optional) (2 bytes) + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.7.3 xDSL line configuration profile part 1** + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (the client PPTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration profile parts). + +It is worth noting that attributes in the line configuration profile family affect the real-time service delivery of an xDSL UNI, e.g., by triggering diagnostics. Despite the fact that they are called profiles, it may be advisable to instantiate a complete set of these MEs for each PPTP xDSL UNI. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) + +**xTU transmission system enabling (xTSE):** This configuration attribute specifies the transmission system coding types to be allowed by the near-end xTU. It is a bit map as defined in Table 9.7.12-1. (R, W, set-by-create) (mandatory) (7 bytes) + +NOTE 1 – This attribute is only 7 bytes long. An eighth byte enabling VDSL2 capabilities is defined in the VDSL2 transmission system enabling attribute of the xDSL line configuration profile part 2 ME. + +**Power management state forced:** This configuration parameter forces the line state of the near-end xTU. It is coded as an integer value with the following definition. + +- 0 Force the line from the L3 idle state to the L0 full-on state. This transition requires the short initialization procedures. After reaching the L0 state, the line may enter into or exit from the L2 low-power state if the L2 state is enabled. If the L0 state is not reached after a vendor-discretionary number of retries or within a vendor-discretionary timeout, an initialization failure occurs. Whenever the line is in the L3 state, it attempts to transition to the L0 state until it is forced into another state through this configuration parameter. +- 2 Force the line from the L0 full-on to the L2 low-power state. This is an out-of-service test value for triggering the L2 mode. +- 3 Force the line from the L0 full-on or L2 low-power state to the L3 idle state. This transition requires the orderly shutdown procedure. After reaching the L3 state, the line remains there until it is forced into another state through this configuration parameter. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Power management state enabling:** The PMMode attribute specifies the line states into which the xTU-C or x digital subscriber line transceiver unit at the remote end (xTU-R) may autonomously go. It is a bit map (0 if not allowed, 1 if allowed) with the following definition. + +Bit 1 (LSB): L3 idle state + +Bit 2: L1/L2 low-power state + +(R, W, set-by-create) (mandatory) (1 byte) + +**Downstream target noise margin:** This attribute specifies the noise margin the xTU-R receiver must achieve, relative to the BER requirement for each of the downstream bearer channels, to successfully complete initialization. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (mandatory) (2 bytes) + +**Upstream target noise margin:** This attribute specifies the noise margin the xTU-C receiver must achieve, relative to the BER requirement for each of the upstream bearer channels, to successfully complete initialization. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (mandatory) (2 bytes) + +**Downstream maximum noise margin:** The MAXSNRMds attribute specifies the maximum noise margin the xTU-R receiver tries to sustain. If the noise margin is above this level, the xTU-R requests the xTU-C to reduce its transmit power, if this functionality is supported by the applicable xDSL Recommendation. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). The special value 0xFFFF indicates that the maximum noise margin limit is unbounded. (R, W, set-by-create) (mandatory) (2 bytes) + +**Upstream maximum noise margin:** The MAXSNRMus attribute specifies the maximum noise margin the xTU-C receiver tries to sustain. If the noise margin is above this level, the xTU-C requests the xTU-R to reduce its transmit power, if this functionality is supported by the applicable xDSL Recommendation. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). The special value 0xFFFF indicates that the maximum noise margin limit is unbounded. (R, W, set-by-create) (mandatory) (2 bytes) + +**Downstream minimum noise margin:** This attribute specifies the minimum noise margin the xTU-R receiver must tolerate. If the noise margin falls below this level, the xTU-R requests the xTU-C to increase its transmit power. If an increase in + +xTU-C transmit power is not possible, a loss-of-margin (LOM) defect occurs, the xTU-R fails and attempts to re-initialize, and the PPTP declares a line initialization failure (LINIT) alarm. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (mandatory) (2 bytes) + +**Upstream minimum noise margin:** This attribute specifies the minimum noise margin the xTU-C receiver must tolerate. If the noise margin falls below this level, the xTU-C requests the xTU-R to increase its transmit power. If an increase in xTU-R transmit power is not possible, an LOM defect occurs, the xTU-C fails and attempts to re-initialize, and the PPTP declares a LINIT alarm. Its value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (mandatory) (2 bytes) + +**Downstream rate adaptation mode:** The RA-MODEs attribute specifies the mode of operation of a rate-adaptive xTU-C in the transmit direction. The parameter can take four values. + +##### **1 Mode 1: MANUAL** – Rate changed manually. + +*At start-up* + +The minimum data rate attribute of the associated xDSL channel configuration profile specifies the minimum required data rate for each downstream bearer channel, with a noise margin that is at least as large as the specified downstream target noise margin, relative to the required BER for each of the downstream bearer channels. If the xTU-C fails to achieve the minimum data rate for any of the downstream bearer channels, the xTU-C fails to initialize and the PPTP declares a LINIT alarm. Although the xTU-C and the line might be able to support a higher data rate, the xTU-C does not transmit a higher data rate than is requested. + +*At showtime* + +The xTU-C transmitter maintains the specified minimum data rate for each of the bearer channels. + +##### **2 Mode 2: AT\_INIT** – Rate automatically selected at start-up only; rate does not change after that. + +*At start-up* + +The minimum data rate attribute of the associated xDSL channel configuration profile specifies the minimum required data rate for each downstream bearer channel, with a noise margin that is at least as large as the specified downstream target noise margin, relative to the required BER for each of the downstream bearer channels. If the xTU-C fails to achieve the minimum data rate for any of the downstream bearer channels, the xTU-C fails to initialize and the PPTP declares a LINIT alarm. If the xTU-C transmitter is able to support a higher downstream data rate at initialization, the excess data rate is distributed among the downstream bearer channels according to the weight specified by the rate adaptation ratio attribute of each bearer channel. When the maximum data rate is achieved in one of the downstream bearer channels, the remaining excess rate is assigned to the other bearer channels, still according to their relative rate adaptation ratios. As long as the downstream data rate is below the downstream + +maximum data rate for one of the bearer channels, data rate increase takes priority over transmit power reduction. + +*At showtime* + +During showtime, no downstream data rate adaptation is allowed. The downstream data rate, determined during initialization for each bearer channel, is maintained. + +**3 Mode 3: DYNAMIC** – Data rate is automatically selected at initialization and is continuously adapted during showtime. The dynamic rate adaptation mode is optional. All related configuration parameters are also optional. + +*At start-up* + +The xTU-C starts up as in mode 2. + +*At showtime* + +During showtime, rate adaptation is allowed according to the rate adaptation ratios for distributing the excess data rate among the bearer channels, as described in mode 2. The downstream data rate can vary between the downstream minimum data rate and the downstream maximum data rate. Downstream rate adaptation is performed when the conditions specified for downstream upshift noise margin and downstream upshift interval – or for downstream downshift noise margin and downstream downshift interval – are satisfied. This means the following. + +- An upshift action is allowed when the downstream noise margin is above the downstream upshift noise margin during the downstream minimum time interval for upshift rate adaptation (RAU; i.e., upon RAU anomaly). +- A downshift action is allowed when the downstream noise margin is below the downstream downshift noise margin during the downstream minimum time interval for downshift rate adaptation (RAD; i.e., upon RAD anomaly). + +As long as the downstream data rate is below the maximum data rate for one of the downstream bearer channels, data rate increase takes priority over transmit power reduction. + +In ITU-T G.993.2 start-up, if it is detected that seamless rate adaptation (SRA) is supported in the downstream direction by neither xTU, the xTUs fall back to mode 2. + +**4 Mode 4: DYNAMIC with SOS** – Data rate is automatically selected at initialization and is continuously adapted during showtime by SOS and SRA. Rate adaptation mode 4 is optional, but if it is selected, enabling of SOS and SRA is mandatory. This mode is defined only in [ITU-T G.993.2]. + +*At start-up* + +The xTU-C starts up as in mode 2. + +*At showtime* + +SRA behaviour is the same as described for mode 3, unless the actual net data rate is below the minimum net data rate as a result of an SOS procedure. + +Additionally, SOS may be performed when the conditions specified by the SOS trigger parameters are satisfied. The detailed specification of the SOS on-line reconfiguration (OLR) procedure appears in [ITU-T G.993.2]. + +If at start-up, it is detected that SOS is supported in the downstream direction by neither xTU, but SRA is supported by both xTUs, the xTUs fall back to mode 3. + +If at start-up, it is detected that neither SOS nor SRA are supported in the downstream direction by both xTUs, the xTUs fall back to mode 2. + +(R, W, set-by-create) (mandatory) (1 byte) + +**Upstream rate adaptation mode:** The RA-MODEus attribute specifies the mode of operation of a rate-adaptive xTU-R in the transmit direction. The parameter is used only if rate-adaptive functionality is supported. It can take four values: + +- 1 MANUAL +- 2 AT\_INIT +- 3 DYNAMIC +- 4 DYNAMIC with SOS + +The definition of each of the values is identical to its definition in the downstream rate adaptation mode, replacing xTU-C with xTU-R and downstream with upstream. (R, W, set-by-create) (mandatory) (1 byte) + +**Downstream upshift noise margin:** If the downstream noise margin is above the downstream upshift noise margin and remains there for more than the time specified by the downstream minimum time interval for upshift rate adaptation, the xTU-R attempts to increase the downstream net data rate. This attribute ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (optional) (2 bytes) + +**Upstream upshift noise margin:** If the upstream noise margin is above the upstream upshift noise margin and remains there for more than the time specified by the upstream minimum time interval for upshift rate adaptation, the xTU-C attempts to increase the upstream net data rate. This attribute ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (optional) (2 bytes) + +**Upstream PSD mask selection:** This attribute enables one of several upstream PSD masks. It is used only for Annexes J and M of [ITU-T G.992.3] and [ITU-T G.992.5]. The same mask selection applies to all relevant modes enabled in the xTSE line configuration parameter (Table 9.7.12-1). This attribute selects the mask with the following definition. + +| | | | +|---|---------|-------| +| 1 | ADLU-32 | EU-32 | +| 2 | ADLU-36 | EU-36 | +| 3 | ADLU-40 | EU-40 | +| 4 | ADLU-44 | EU-44 | +| 5 | ADLU-48 | EU-48 | +| 6 | ADLU-52 | EU-52 | +| 7 | ADLU-56 | EU-56 | +| 8 | ADLU-60 | EU-60 | +| 9 | ADLU-64 | EU-64 | + +(R, W, set-by-create) (mandatory) (1 byte) + +**Minimum overhead rate upstream:** This attribute specifies the minimum rate of the message based overhead to be maintained by the xTU in the upstream direction. MSGMINus ranges from 4000 to 248 000 bit/s. The value 0 specifies that the ONU uses its internal default. This attribute is only valid for [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. (R, W, set-by-create) (optional) (2 bytes) + +NOTE 2 – For compatibility with previous versions of the OMCI, values between 4000 and 65535 are interpreted as bits per second. To align with [ITU-T G.997.1], values between 4 and 248 are interpreted as kilobits per second. For maximum flexibility, the ONU should support both conventions. + +**Minimum overhead rate downstream:** This attribute specifies the minimum rate of the message based overhead to be maintained by the xTU in the downstream direction. MSGMINds ranges from 4000 to 248 000 bit/s. The value 0 specifies that the ONU uses its internal default. This attribute is only valid for [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. (R, W, set-by-create) (optional) (2 bytes) + +NOTE 3 – For compatibility with previous versions of the OMCI, values between 4000 and 65535 are interpreted as bits per second. To align with [ITU-T G.997.1], values between 4 and 248 are interpreted as kilobits per second. For maximum flexibility, the ONU should support both conventions. + +#### Actions + +Create, delete, get, set + +#### Notifications + +None. + +### 9.7.4 xDSL line configuration profile part 2 + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (the client PPTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration profile parts). + +#### Relationships + +An instance of this ME may be associated with zero or more instances of an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**Downstream minimum time interval for upshift rate adaptation:** This parameter defines the interval during which the downstream noise margin must remain above the downstream upshift noise margin before the xTU-R attempts to increase the downstream net data rate. Its value ranges from 0 to 16383 s. (R, W, set-by-create) (optional) (2 bytes) + +**Upstream minimum time interval for upshift rate adaptation:** This parameter defines the interval during which the upstream noise margin must remain above the upstream upshift noise margin before the xTU-C attempts to increase the upstream net data rate. Its value ranges from 0 to 16383 s. (R, W, set-by-create) (optional) (2 bytes) + +**Downstream downshift noise margin:** If the downstream noise margin is below the downstream downshift noise margin and remains there for more than the downstream minimum time interval for downshift rate adaptation, the xTU-R attempts to decrease the downstream net data rate. This attribute's value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (optional) (2 bytes) + +**Upstream downshift noise margin:** If the upstream noise margin is below the upstream downshift noise margin and remains there for more than the upstream minimum time interval for downshift rate adaptation, the xTU-C attempts to decrease the upstream net data rate. This attribute's value ranges from 0 (0.0 dB) to 310 (31.0 dB). (R, W, set-by-create) (optional) (2 bytes) + +**Downstream minimum time interval for downshift rate adaptation:** This parameter defines the interval during which the downstream noise margin must remain below the downstream downshift noise margin before the xTU-R attempts to decrease the downstream net data rate. Its value ranges from 0 to 16383 s. (R, W, set-by-create) (optional) (2 bytes) + +**Upstream minimum time interval for downshift rate adaptation:** This parameter defines the interval during which the upstream noise margin must remain below the upstream downshift noise margin before the xTU-C attempts to decrease the upstream net data rate. Its value ranges from 0 to 16383 s. (R, W, set-by-create) (optional) (2 bytes) + +**xTU impedance state forced:** This parameter forces the impedance state of the xTU-C. It applies only to the T/S interface, and is deprecated in the OMCI, which stands proxy for the Q interface. It is only valid for Annex A of [ITU-T G.992.3], Annex A of [ITU-T G.992.4] and Annex A of [ITU-T G.992.5]. It is defined as follows. + +- 1 Force the xTU-C to the disabled state. +- 2 Force the xTU-C to the inactive state. +- 3 Force the xTU-C to the active state. + +(R, W, set-by-create) (optional) (1 byte) + +**L0-time:** This parameter specifies the minimum time between an exit from the L2 state and the next entry into the L2 state. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. It ranges from 0 to 255 s. (R, W, set-by-create) (mandatory) (1 byte) + +- L2-time:** This parameter specifies the minimum time between an entry into the L2 state and the first power trim in the L2 state, or between two consecutive power trims in the L2 state. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. It ranges from 0 to 255 s. (R, W, set-by-create) (mandatory) (1 byte) +- Downstream maximum nominal power spectral density:** This attribute specifies the maximum nominal transmit PSD in the downstream direction during initialization and showtime. A single MAXNOMPSDds attribute is defined per mode enabled in the xTSE line configuration attribute. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. Its value ranges from 0 (–60.0 dBm/Hz) to 300 (–30 dBm/Hz). (R, W, set-by-create) (mandatory) (2 bytes) +- Upstream maximum nominal power spectral density:** This attribute specifies the maximum nominal transmit PSD in the upstream direction during initialization and showtime. A single MAXNOMPSDus attribute is defined per mode enabled in the xTSE line configuration attribute. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.993.2]. Its value ranges from 0 (–60.0 dBm/Hz) to 300 (–30 dBm/Hz). (R, W, set-by-create) (mandatory) (2 bytes) +- Downstream maximum nominal aggregate transmit power:** This attribute specifies the maximum nominal aggregate transmit power in the downstream direction during initialization and showtime. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. Its value ranges from 0 (0.0 dBm) to 255 (25.5 dBm). (R, W, set-by-create) (mandatory) (1 byte) +- Upstream maximum nominal aggregate transmit power:** This parameter specifies the maximum nominal aggregate transmit power in the upstream direction during initialization and showtime. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. Its value ranges from 0 (0.0 dBm) to 255 (25.5 dBm). (R, W, set-by-create) (mandatory) (1 byte) +- Upstream maximum aggregate receive power:** This parameter specifies the maximum upstream aggregate receive power over a set of subcarriers, as defined in the relevant Recommendation. The xTU-C requests an upstream power cutback such that the upstream aggregate receive power over that set of subcarriers is at or below the configured maximum value. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. This attribute ranges from 0 (–25.5 dBm) to 510 (+25.5 dBm). The special value 0xFFFF indicates that no upstream maximum aggregate receive power limit is to be applied. (R, W set-by-create) (mandatory) (2 bytes) +- VDSL2 transmission system enabling:** This configuration attribute extends the transmission system coding types to be allowed by the xTU-C. It is a bit map, defined as octet 8 (bits 57..64) in Table 9.7.12-1. (R, W, set-by-create) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.7.5 xDSL line configuration profile part 3 + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (the client PPTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration profile parts). + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**Loop diagnostics mode forced (LDSF):** This configuration parameter forces the line into loop diagnostic mode via the xTU-C. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. It is defined as follows. + +- 0 Inhibits the xTU-C from performing loop diagnostic mode procedures on the line. Loop diagnostic mode procedures may still be initiated by the xTU-R. +- 1 Forces the xTU-C to perform loop diagnostics procedures. + +Only while the line power management state is L3 can the line be forced into loop diagnostic mode. When loop diagnostic procedures complete successfully, the ONU resets this attribute to 0. The line remains in the L3 idle state. The loop diagnostics data are available at least until the line is forced to the L0 state. As long as loop diagnostic procedures have not completed successfully, attempts are made to do so, until the loop diagnostic mode is no longer forced on the line through this configuration parameter. If loop diagnostic procedures cannot be completed successfully after a vendor-discretionary number of retries or within a vendor-discretionary timeout, then an initialization failure occurs. (R, W, set-by-create) (mandatory) (1 byte) + +**Automode cold start forced:** This attribute is defined to improve testing of the performance of xTUs supporting automode. Valid values are 0 and 1. A change in value of this attribute indicates a change in loop conditions applied to the devices under test. The xTUs reset any historical information used for automode, for shortening an ITU-T G.994.1 handshake, or for shortening the initialization procedure. + +Automode is defined as the case where multiple operation modes are enabled in xTSE (Table 9.7.12-1) and where the selection of the operation mode to be used for transmission depends, not only on the common capabilities of both xTUs (as exchanged in [ITU-T G.994.1]), but also on achievable data rates under given loop conditions. (R, W, set-by-create) (mandatory if automode is supported) (1 byte) + +**L2-ATPR:** This parameter specifies the maximum aggregate transmit power reduction that can be performed in the L2 request (i.e., at the transition of L0 to L2 state) or through a single power trim in the L2 state. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. This attribute ranges from 0 (0 dB) to 31 (31 dB). (R, W, set-by-create) (mandatory) (1 byte) + +**L2-ATPRT:** This parameter specifies the total maximum aggregate transmit power reduction (in decibels) that can be performed in an L2 state. This is the sum of + +all reductions of L2 requests (i.e., at transitions from L0 to L2 state) and power trims. This attribute ranges from 0 (0 dB) dB to 31 (31 dB). (R, W, set-by-create) (mandatory) (1 byte) + +**Force INP downstream:** When set to 1, the FORCEINPds attribute forces the framer settings of all downstream bearer channels to be selected such that the impulse noise protection (INP) computed according to the formula specified in the relevant Recommendation is greater than or equal to the minimal INP requirement. The default value 0 disables this function. (R, W) (mandatory for [ITU-T G.993.2], optional for other Recommendations that support it) (1 byte) + +**Force INP upstream:** When set to 1, the FORCEINPus attribute forces the framer settings of all upstream bearer channels to be selected such that the INP computed according to the formula specified in the relevant Recommendation is greater than or equal to the minimal INP requirement. The default value 0 disables this function. (R, W) (mandatory for [ITU-T G.993.2], optional for other Recommendations that support it) (1 byte) + +**Update request flag for near-end test parameters:** The UPDATE-TEST-NE attribute forces an update of all near-end test parameters that can be updated during showtime in [ITU-T G.993.2]. Update is triggered by setting this attribute to 1, whereupon the near-end test parameters are expected to be updated within 10 s, and the ONU should reset the attribute value to 0. The update request flag is independent of any autonomous update process in the system. The update request attribute must be prepared to accept another set after a period not to exceed 3 min, a period that starts when the flag is set via the OMCI or by an autonomous process in the system. (R, W) (optional) (1 byte) + +**Update request flag for far-end test parameters:** The UPDATE-TEST-FE attribute forces an update of all far-end test parameters that can be updated during showtime in [ITU-T G.993.2]. Update is triggered by setting this attribute to 1, whereupon the far-end test parameters are expected to be updated within 10 s, and the ONU should reset the attribute value to 0. The update request flag is independent of any autonomous update process in the system. The update request attribute must be prepared to accept another set after a period not to exceed 3 min, a period that starts when the flag is set via the OMCI or by an autonomous process in the system. (R, W) (optional) (1 byte) + +The following eight attributes configure the impulse noise monitoring (INM) function, whose results are available via the xDSL impulse noise monitor PM history data ME. The downstream attributes are applicable to [ITU-T G.993.2], [ITU-T G.992.3] and [ITU-T G.992.5]. Only [ITU-T G.993.2] supports the upstream attributes. + +**INM inter-arrival time offset upstream:** INMIATous is the inter-arrival time (IAT) offset that the xTU-C receiver uses to determine in which bin of the IAT histogram the IAT is reported. Valid values for INMIATO range from 3 to 511 discrete multi-tone (DMT) symbols in steps of 1 DMT symbol. (R, W) (optional) (2 bytes) + +**INM inter-arrival time step upstream:** INMIATSus is the IAT step that the xTU-C receiver uses to determine in which bin of the IAT histogram the IAT is reported. Valid values for INMIATS range from 0 to 7 in steps of 1. (R, W) (optional) (1 byte) + +**INM cluster continuation value upstream:** INMCCus is the cluster continuation value that the xTU-C receiver uses in the cluster indication process described in the applicable Recommendation. Valid values for INMCC range from 0 to 64 DMT symbols in steps of 1 DMT symbol. (R, W) (optional) (1 byte) + +- INM equivalent INP mode upstream:** INM\_INPEQ\_MODEus is the INM equivalent INP mode that the xTU-C receiver uses in the computation of the equivalent INP, as defined in the applicable Recommendation. Valid values for INM\_INPEQ\_MODE are 0..4. (R, W) (optional) (1 byte) +- INM inter-arrival time offset downstream:** INMIATODs is the IAT offset that the xTU-R receiver uses to determine in which bin of the IAT histogram the IAT is reported. Valid values for INMIATO range from 3 to 511 DMT symbols in steps of 1 DMT symbol. (R, W) (optional) (2 bytes) +- INM inter-arrival time step downstream:** INMIATSds is the IAT step that the xTU-R receiver uses to determine in which bin of the IAT histogram the IAT is reported. Valid values for INMIATS range from 0 to 7 in steps of 1. (R, W) (optional) (1 byte) +- INM cluster continuation value downstream:** INMCCds is the cluster continuation value that the xTU-R receiver uses in the cluster indication process described in the applicable Recommendation. Valid values for INMCC range from 0 to 64 DMT symbols in steps of 1 DMT symbol. (R, W) (optional) (1 byte) +- INM equivalent INP mode downstream:** INM\_INPEQ\_MODEds is the INM equivalent INP mode that the xTU-R receiver uses in the computation of the equivalent INP, as defined in the applicable Recommendation. Valid values for INM\_INPEQ\_MODE are 0..4. (R, W) (optional) (1 byte) + +#### Actions + +Create, delete, get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|------------------------------------------------------------------------------------------------------------| +| 1..6 | N/A | | +| 7 | Update request NE | Need only be reported on the 1 → 0 transition to signal to the OLT that test parameters have been updated. | +| 8 | Update request FE | Need only be reported on the 1 → 0 transition to signal to the OLT that test parameters have been updated. | +| 9..16 | N/A | | + +### 9.7.6 VDSL2 line configuration extensions + +This ME extends the xDSL line configuration MEs with attributes that were originally unique to ITU-T G.993.2 VDSL2. Due to continuing standards development, some attributes – and therefore this ME – have also become applicable to other Recommendations, specifically [ITU-T G.992.3] and [ITU-T G.992.5]. The attributes of this ME are further defined in [ITU-T G.997.1]. An instance of this ME is created and deleted by the OLT. + +#### Relationships + +An instance of this ME may be associated with zero or more instances of an xDSL UNI. + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (the client PPTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration parts). + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**VDSL2 profiles enabling:** The PROFILES attribute contains the ITU-T G.993.2 profiles to be allowed by the xTU-C. It is coded in a bit map representation (0 if not allowed, 1 if allowed) with the following definition. + +| Bit | Meaning | +|---------|---------------------------| +| 1 (LSB) | ITU-T G.993.2 profile 8a | +| 2 | ITU-T G.993.2 profile 8b | +| 3 | ITU-T G.993.2 profile 8c | +| 4 | ITU-T G.993.2 profile 8d | +| 5 | ITU-T G.993.2 profile 12a | +| 6 | ITU-T G.993.2 profile 12b | +| 7 | ITU-T G.993.2 profile 17a | +| 8 | ITU-T G.993.2 profile 30a | + +(R, W, set-by-create) (mandatory for ITU-T G.993.2) (1 byte) + +**VDSL2 PSD mask class selection (CLASSMASK):** To reduce the number of configuration possibilities, the limit PSD masks are grouped in the following PSD mask classes. + +- Class 998 Annex A of [ITU-T G.993.2]: D-32, D-48, D-64, D-128 +- Class 997-M1c Annex B of [ITU-T G.993.2]: 997-M1c-A-7 +- Class 997-M1x Annex B of [ITU-T G.993.2]: 997-M1x-M +- Class 997-M2x Annex B of [ITU-T G.993.2]: 997E17-M2x-NUS0, 997E30-M2x-NUS0 +- Class 998-M2x Annex B of [ITU-T G.993.2]: 998-M2x-A, 998-M2x-M, 998-M2x-B, 998-M2x-NUS0, 998E17-M2x-NUS0, 998E17-M2x-NUS0-M, 998E30-M2x-NUS0, 998E30-M2x-NUS0-M, 998E17-M2x-A +- Class 998ADE-M2x Annex B of [ITU-T G.993.2]: 998-M2x-A, 998-M2x-M, 998-M2x-B, 998-M2x-NUS0, 998ADE17-M2x-A, 998ADE17-M2x-B, 998ADE17-M2x-M, 998ADE17-M2x-NUS0-M, 998ADE30-M2x-NUS0-A, 998ADE30-M2x-NUS0-M, HPEADE1230, HPEADE1730 +- Class 998-B Annex C: POTS-138b, POTS-276b (clause C.2.1.1 of [ITU-T G.993.2]), TCM-ISDN (clause C.2.1.2 of [ITU-T G.993.2]) +- Class 998-CO Annex C of [ITU-T G.993.2]: POTS-138co, POTS-276co (clause C.2.1.1 of [ITU-T G.993.2]) +- Class HPE-M1 Annex B of [ITU-T G.993.2]: HPE17-M1-NUS0, HPE30-M1-NUS0, HPE1230-M1-NUS0, HPE1730-M1-NUS0 + +Each class is designed such that the PSD levels of each limit PSD mask of a specific class are equal in their respective passbands above 552 kHz. + +The CLASSMASK attribute is defined per annex of [ITU-T G.993.2] enabled in the xTSE table (see Table 9.7.12-1). It selects a single PSD mask class per annex of [ITU-T G.993.2] to be activated at the very high-speed digital subscriber line transceiver unit, operator end (VTU-O). The coding is as follows: + +| Attribute value | Annex A of [ITU-T G.993.2] | Annex B of [ITU-T G.993.2] | Annex C of [ITU-T G.993.2] | +|-----------------|----------------------------|----------------------------|----------------------------| +| 1 | 998 | 997-M1c | 998-B | +| 2 | | 997-M1x | 998-CO | +| 3 | | 997-M2x | | +| 4 | | Deprecated | | +| 5 | | 998-M2x | | +| 6 | | 998ADE-M2x | | +| 7 | | HPE | | + +NOTE 1 – A single PSD mask class may be selected per annex of [ITU-T G.993.2]. + +NOTE 2 – It is expected that only a single annex will be enabled at any given time, such that the CLASSMASK attribute, as well as the LIMITMASK and US0DISABLE attributes below, need not be vectors of values. + +NOTE 3 – Attribute value 4 was formerly defined in [ITU-T G.997.1], and is no longer used. + +(R, W, set-by-create) (mandatory) (1 byte) + +**VDSL2 limit PSD masks:** The LIMITMASK attribute contains the ITU-T G.993.2 limit PSD masks of the selected PSD mask class, enabled by the near-end xTU for each class of profiles. One LIMITMASK parameter is defined per annex enabled in the xTSE (see Table 9.7.12-1). + +The profiles are grouped in the following profile classes: + +- Class 8: Profiles 8a, 8b, 8c, 8d +- Class 12: Profiles 12a, 12b +- Class 17: Profile 17a +- Class 30: Profile 30a + +For each profile class, several limit PSD masks of the selected PSD mask class (CLASSMASK) may be enabled. The enabling attribute is coded in a bit map representation (0 if the associated mask is not allowed, 1 if it is allowed). The bit mask is defined in Table 9.7.6-1. (R, W, set-by-create) (mandatory) (8 bytes) + +**VDSL2 US0 disabling:** The US0DISABLE attribute specifies whether channel US0 is disabled for each limit PSD mask enabled in the LIMITMASK attribute. + +For each limit PSD mask enabled in the LIMITMASK attribute, one bit indicates if US0 is disabled. The disabling attribute is a bit map where the value 1 specifies that US0 is disabled for the associated limit mask. The bit map has the same structure as the LIMITMASK attribute. (R, W, set-by-create) (mandatory) (8 bytes) + +**VDSL2 US0 PSD masks:** The US0MASK attribute contains the US0 PSD masks to be allowed by the xTU-C. This attribute is only defined for Annex A of [ITU-T G.993.2]. It is represented as a bit map (0 if not allowed, 1 if allowed) with the definitions of Table 9.7.6-2. (R, W, set-by-create) (mandatory) (4 bytes) + +**VDSL2-CARMASK table:** This attribute specifies restrictions, additional to the band plan, that determine the set of subcarriers allowed for transmission in both upstream and downstream directions. + +The VDSL2-CARMASK attribute describes the not-masked subcarriers in terms of one or more frequency bands. Each band is represented by start and stop subcarrier indices with a subcarrier spacing of 4.3125 kHz. The valid range of subcarrier indices is from 0 to at least the index of the highest allowed subcarrier in both transmission directions among all profiles enabled by the VDSL2 profiles enabling (PROFILES) attribute. Up to 32 bands may be specified. Other subcarriers are masked. + +For profiles using 8.625 kHz tone spacing, the odd subcarrier indices $i_{4.3125}$ in VDSL2-CARMASK can be transformed into actual subcarrier indices $i_{8.625}$ using the following rule: + +- for the start frequency of each band: $i_{8.625} = (i_{4.3125} + 1)/2$ +- for the stop frequency of each band: $i_{8.625} = (i_{4.3125} - 1)/2$ . + +The VDSL2-CARMASK attribute is a table where each entry comprises: + +- an entry number field (1 byte, first entry numbered 1); +- band start subcarrier index (2 bytes); +- band stop subcarrier index (2 bytes). + +By default, the table is empty. Entries are added or modified using the set action. Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier references to zero implies deletion from the table, if present. + +The maximum number of bands is 32, so the maximum size of the table is 160 bytes. (R, W) (mandatory) (5 \* $N$ bytes, where $N$ is the number of bands) + +**CARMASK valid:** This attribute controls and reports the status of the VDSL2-CARMASK table. If CARMASK valid = 1, then the VDSL2-CARMASK has been effectuated on the xDSL equipment. If CARMASK valid = 0 (default), then the VDSL2-CARMASK table is under construction and has not been effectuated on the xDSL equipment. + +This attribute behaves as follows. + +- If the OLT changes any of the VDSL2-CARMASK table entries or sets CARMASK valid = 0, then CARMASK valid = 0. +- If CARMASK valid = 0 and the OLT sets CARMASK valid = 1, then the ONU updates the xDSL equipment with the contents of the table. + +(R, W) (mandatory) (1 byte) + +**UPBOSHAPED:** Upstream power back-off (UPBO) is specified in [ITU-T G.993.2] to provide spectral compatibility between loops of different lengths deployed in the same cable binder. The upstream transmit PSD mask, UPBOMASKus is defined in clause 7.2.1.3.2 of [ITU-T G.993.2]. + +The ITU-T G.993.2 UPBO configuration attributes $a$ and $b$ are set by the OLT via this attribute. The reference length $kl_{0\_REF}$ is set by the companion attribute UPBO $kl_{REF-pb}$ , defined in the following. Further details appear in [ITU-T G.997.1]. + +This attribute includes two parameters for each band. The parameters are *a* and *b*, in that order. Parameter *a* lies in the range 4000 (40.00 dBm/Hz) to 8095 (80.95 dBm/Hz). Parameter *b* lies in the range 0 (0.00 dBm/Hz) to 4095 (40.95 dBm/Hz). The special values *a* = *b* = 0 disable UPBO in the respective upstream band. + +The upstream electrical length parameter UPBOKL defines the electrical length expressed in decibels at 1 MHz, *kl*0, which may also be configured by the OLT. Its value ranges from 0 (0.0 dB) to 1280 (128.0 dB). + +If the force electrical length parameter UPBOKLF is 1, the very high-speed digital subscriber line transceiver unit, remote end (VTU-R) is forced to use the electrical length from this attribute (UPBOKL) to compute UPBO. Otherwise, the VDSL2 transceiver units (VTUs) determine the electrical length themselves. + +| | | | +|-----------------|----------|---------| +| Upstream band 1 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 2 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 3 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 4 | a | 2 bytes | +| | b | 2 bytes | +| Upstream band 5 | a | 2 bytes | +| | b | 2 bytes | +| UPBOKL | | 2 bytes | +| UPBOKLF | | 1 byte | + +(R, W) (mandatory) (23 bytes) + +**Cyclic extension:** The CEFLAG attribute enables (1) the optional cyclic extension values. If set to 0, the cyclic extension is forced to the mandatory length *5N/32*. (R, W) (mandatory) (1 byte) + +**Downstream signal-to-noise ratio (SNR) mode:** The SNRMODEDs attribute controls transmitter referred virtual noise in the downstream direction. If set to 1, virtual noise is disabled. If set to 2, virtual noise is enabled. (R, W) (mandatory) (1 byte) + +**Upstream SNR mode:** The SNRMODEUs attribute controls transmitter referred virtual noise in the upstream direction. If set to 1, virtual noise is disabled. If set to 2, virtual noise is enabled. (R, W) (mandatory) (1 byte) + +**Transmitter referred virtual noise downstream table:** The TXREFVNDs table defines the downstream transmitter referred virtual noise. TXREFVNDs is specified through a set of breakpoints. Each breakpoint comprises a subcarrier index *t*, with a subcarrier spacing of 4.3125 kHz, and a noise PSD level at that subcarrier. The set of breakpoints can then be represented as [(*t*1, PSD1), (*t*2, PSD2), ..., (*t*N, PSDN)]. The subcarrier index *t* is an unsigned 2 byte integer. The noise level is 1 byte whose value ranges from 0 (–40 dBm/Hz) to 200 (–140 dBm/Hz), in steps of 0.5 dB. Values between 201 and 254 indicate a noise PSD level of 0 W/Hz. The maximum number of breakpoints is 32; no more + +than 15 breakpoints may be configured below the upper edge of the passband of every mode enabled for [ITU-T G.992.3] and [ITU-T G.992.5]. + +Table entries for this attribute have the default value 254 for the noise PSD level. Entries are added or modified using the set action. Setting an entry to a noise PSD level less than or equal to 254 implies insertion into the table. Setting an entry's noise PSD level to 255 implies deletion from the table, if present. + +(R, W) (optional) ( $3N$ bytes, where $N$ is the number of breakpoints) + +**Transmitter referred virtual noise upstream table:** The TXREFVNus attribute defines the upstream transmitter referred virtual noise. TXREFVNus is specified through a set of breakpoints. Each breakpoint comprises a subcarrier index $t$ , with a subcarrier spacing of 4.3125 kHz, and a noise PSD level at that subcarrier. The set of breakpoints can then be represented as $[(t_1, \text{PSD}_1), (t_2, \text{PSD}_2), \dots, (t_N, \text{PSD}_N)]$ . The subcarrier index $t$ is an unsigned 2 byte integer. The noise level is 1 byte whose value ranges from 0 ( $-40$ dBm/Hz) to 200 ( $-140$ dBm/Hz), in steps of 0.5 dB. Values between 201 and 254 indicate a noise PSD level of 0 W/Hz. The maximum number of breakpoints is 16; no more than three breakpoints may be configured below the upper edge of the passband of every mode enabled for [ITU-T G.992.3] and [ITU-T G.992.5]. + +Table entries for this attribute have the default value 254 for the noise PSD level. Entries are added or modified using the set action. Setting an entry to a noise PSD level less than or equal to 254 implies insertion into the table. Setting an entry's noise PSD level to 255 implies deletion from the table, if present. + +(R, W) (optional) ( $3N$ bytes, where $N$ is the number of breakpoints) + +**DPBOSHAPED:** Downstream power back-off – shaped is described in [ITU-T G.997.1] as a vector of parameters that modifies the downstream PSD mask. + +**DPBOEPSD** – Assumed exchange PSD mask. This component points to a downstream xDSL PSD mask profile ME. The PSD mask profile should contain no more than 16 break points. (2 bytes) + +**DPBOESEL** – E-side electrical length. This component is the assumed loss at some reference frequency of the electrical cable from the xDSL equipment to a possible flexibility point. It ranges from 0 (0.0 dB) to 511 (255.5 dB) in steps of 0.5 dB. The value 0 has the special meaning that it disables the DPBOSHAPED feature. (2 bytes) + +The following three parameters describe the cable model. Further details appear in [ITU-T G.997.1]. Each is a scalar that represents the range $-1$ (coded as 0) to $+1.5$ (coded as 640) in steps of $1/256$ . + +**DPBOESCMA** – (2 bytes) + +**DPBOESCMB** – (2 bytes) + +**DPBOESCMC** – (2 bytes) + +**DPBOMUS** – Assumed minimum usable receive PSD mask. This component ranges from 0 (0.0 dBm/Hz) to 255 ( $-127.5$ dBm/Hz) in steps of 0.5 dB. (1 byte) + +**DPBOFMIN** – The lower frequency bound above which DPBO is applied. This component ranges from 0 (0.00 kHz) to 2048 (8832.00 kHz) in steps of 4.3125 kHz. (2 bytes) + +**DPBOFMAX** – The upper frequency bound below which DPBO is applied. This component ranges from 32 (138.00 kHz) to 6956 (29997.75 kHz) in steps of 4.3125 kHz. (2 bytes) + +(R, W) (optional) (15 bytes) + +**UPBOKLREF-pb**: This attribute represents the reference loop length, the electrical length used to compute upstream power back-off (UPBO) for each upstream band except US0, for the optional equalized FEXT UPBO method. The value for each upstream band ranges from 1.8 to 63.5 dB in steps of 0.1 dB, i.e., with values 18..635. The special value 0 is also allowed, with semantics as defined in clause 7.2.1.3.2 of [ITU-T G.993.2]. (R, W) (optional) (2 bytes \* 5 upstream bands) + +**UPBOSHAPED (AELE-MODE, UPBOELMT)**: This attribute defines the UPBO electrical length estimation mode (AELE-MODE) and UPBO electrical length minimum threshold percentile (UPBOELMT) to be used in the alternative electrical length estimation method (ELE-M1). The format of this attribute is given in octet 1 of Table 12-27 of [ITU-T G.993.2]. (R, W) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +**Table 9.7.6-1 – Limit mask definitions for each class mask** + +| | PSD mask classes | | | | | | | | | | +|---------------------------|------------------|---------|--------------------|---------------------------|--------------------|--------------------|--------------------|-------------------|------------------|-------------------| +| | Annex A | Annex B | | | | | | | Annex C | | +| Bit | 998
Annex A | | 998-M2x
Annex B | 998ADE-
M2x
Annex B | 997-M1x
Annex B | 997-M1c
Annex B | 997-M2x
Annex B | HPE-M1
Annex B | 998-B
Annex C | 998-CO
Annex C | +| Octet 1, profile class 8 | | | | | | | | | | | +| 1 | D-32 | | M2x-A | M2x-A | | M1c-A-7 | | | POTS-138b | POTS-138co | +| 2 | D-48 | | M2x-B | M2x-B | | | | | TCM-ISDN | POTS-276co | +| 3 | | | M2x-M | M2x-M | M1x-M | | | | POTS-276b | | +| 4 | | | M2x-NUS0 | M2x-NUS0 | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 2, profile class 8 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 3, profile class 12 | | | | | | | | | | | +| 1 | D-32 | | M2x-A | M2x-A | | | | | POTS-138b | POTS-138co | +| 2 | D-48 | | M2x-B | M2x-B | | | | | TCM-ISDN | POTS-276co | +| 3 | | | M2x-M | M2x-M | M1x-M | | | | POTS-276b | | +| 4 | | | M2x-NUS0 | M2x-NUS0 | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 4, profile class 12 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 5, profile class 17 | | | | | | | | | | | + +**Table 9.7.6-1 – Limit mask definitions for each class mask** + +| | PSD mask classes | | | | | | | | | | +|---------------------------|------------------|---------|------------------------|---------------------------|--------------------|--------------------|----------------------|-------------------|------------------|-------------------| +| | Annex A | Annex B | | | | | | | Annex C | | +| Bit | 998
Annex A | | 998-M2x
Annex B | 998ADE-
M2x
Annex B | 997-M1x
Annex B | 997-M1c
Annex B | 997-M2x
Annex B | HPE-M1
Annex B | 998-B
Annex C | 998-CO
Annex C | +| 1 | D-32 | | E17-
M2x-
NUS0 | ADE17-
M2x-A | | | E17-
M2x-
NUS0 | 17-M1-
NUS0 | POTS-
138b | | +| 2 | D-48 | | E17-
M2x-
NUS0-M | ADE17-
M2x-B | | | | | TCM-
ISDN | | +| 3 | | | E17-
M2x-A | ADE17-
M2x-
NUS0-M | | | | | POTS-
276b | | +| 4 | | | | ADE17-
M2x-M | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 6, profile class 17 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| Octet 7, profile class 30 | | | | | | | | | | | +| 1 | D-32 | | E30-
M2x-
NUS0 | ADE30-
M2x-
NUS0-A | | | E30-
M2x-
NUS0 | 30-M1-
NUS0 | POTS-
138b | | +| 2 | D-48 | | E30-
M2x-
NUS0-M | ADE30-
M2x-
NUS0-M | | | | 1230-M1-
NUS0 | TCM-
ISDN | | +| 3 | | | | HPEADE
1230-
NUS0 | | | | 1730-M1-
NUS0 | POTS-
276b | | +| 4 | | | | HPEADE
1730-
NUS0 | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | + +**Table 9.7.6-1 – Limit mask definitions for each class mask** + +| | PSD mask classes | | | | | | | | | | +|------------------------------------------|------------------|---------|--------------------|---------------------------|--------------------|--------------------|--------------------|-------------------|------------------|-------------------| +| | Annex A | Annex B | | | | | | | Annex C | | +| Bit | 998
Annex A | | 998-M2x
Annex B | 998ADE-
M2x
Annex B | 997-M1x
Annex B | 997-M1c
Annex B | 997-M2x
Annex B | HPE-M1
Annex B | 998-B
Annex C | 998-CO
Annex C | +| Octet 8, profile class 30 | | | | | | | | | | | +| 1 | D-64 | | | | | | | | | | +| 2 | D-128 | | | | | | | | | | +| 3 | | | | | | | | | | | +| 4 | | | | | | | | | | | +| 5 | | | | | | | | | | | +| 6 | | | | | | | | | | | +| 7 | | | | | | | | | | | +| 8 | | | | | | | | | | | +| NOTE – All unassigned bits are reserved. | | | | | | | | | | | + +NOTE – Some entries in this table have been modified relative to earlier versions of this Recommendation. See [ITU-T G.997.1] for details. + +**Table 9.7.6-2 – VDSL2 US0 PSD masks definition** + +| Bit | US0MASK, Annex A of [ITU-T G.993.2] | +|----------------|-------------------------------------| +| Octet 1 | | +| 1 | EU-32 | +| 2 | EU-36 | +| 3 | EU-40 | +| 4 | EU-44 | +| 5 | EU-48 | +| 6 | EU-52 | +| 7 | EU-56 | +| 8 | EU-60 | +| Octet 2 | | +| 1 | EU-64 | +| 2 | EU-128 | +| 3 | Reserved | +| 4 | Reserved | +| 5 | Reserved | +| 6 | Reserved | +| 7 | Reserved | +| 8 | Reserved | +| Octet 3 | | +| 1 | ADLU-32 | +| 2 | ADLU-36 | +| 3 | ADLU-40 | +| 4 | ADLU-44 | +| 5 | ADLU-48 | + +**Table 9.7.6-2 – VDSL2 US0 PSD masks definition** + +| | | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------| +| 6 | ADLU-52 | +| 7 | ADLU-56 | +| 8 | ADLU-60 | +| Octet 4 | | +| 9 | ADLU-64 | +| 10 | ADLU-128 | +| 11 | Reserved | +| 12 | Reserved | +| 13 | Reserved | +| 14 | Reserved | +| 15 | Reserved | +| 16 | Reserved | +| NOTE 1 – Valid combinations of US0MASK and LIMITMASK are described in [ITU-T G.993.2].
NOTE 2 – More than one mask may be enabled simultaneously. If no US0 PSD masks are enabled, the line is configured without US0 support. | | + +### 9.7.7 xDSL channel configuration profile + +This ME contains the channel configuration profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +NOTE – If [ITU-T G.997.1] compatibility is required, bit rates should only be set to integer multiples of 1000 bits/s. The ONU may reject attempts to set other values for bit rate attributes. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Minimum data rate:** This parameter specifies the minimum desired net data rate for the bearer channel. It is coded in bits per second. (R, W, set-by-create) (mandatory) (4 bytes) + +**Maximum data rate:** This parameter specifies the maximum desired net data rate for the bearer channel. It is coded in bits per second. (R, W, set-by-create) (mandatory) (4 bytes) + +**Rate adaptation ratio:** This attribute specifies the weight that should be taken into account when performing rate adaptation in the direction of the bearer channel. The attribute is defined as a percentage. The value 20, for example, means that 20% of the available data rate (in excess of the minimum data rate summed over all bearer channels) is assigned to this bearer channel and 80% to the other bearer channels. The OLT must ensure that the sum of rate adaptation ratios over all bearers in one direction is 100%. (R, W, set-by-create) (optional) (1 byte) + +**Maximum interleaving delay:** This attribute is the maximum one-way interleaving delay introduced by the PMS-TC between the alpha and the beta reference points, in the direction of the bearer channel. The one-way interleaving delay is defined + +in individual xDSL Recommendations as $\text{cap}(S*D)/4$ ms, where $S$ is the $S$ factor, $D$ is the interleaving depth, and $\text{cap}()$ denotes rounding to the next higher integer. xTUs choose $S$ and $D$ values such that the actual one-way interleaving delay does not exceed the configured maximum interleaving delay. + +The delay is coded in milliseconds, varying from 2 to 63, with special meaning assigned to values 0, 1 and 255. The value 0 indicates that no delay bound is imposed. The value 1 indicates the fast latency path is to be used in the ITU-T G.992.1 operating mode and $S$ and $D$ are to be selected such that $S \leq 1$ and $D = 1$ in ITU-T G.992.2, ITU-T G.992.3, ITU-T G.992.4, ITU-T G.992.5 and ITU-T G.993.2 operating modes. The value 255 indicates a delay bound of 1 ms in ITU-T G.993.2 operation. (R, W, set-by-create) (mandatory) (1 byte) + +**Data rate threshold upshift:** This attribute is a threshold on the cumulative data rate upshift achieved over one or more bearer channel data rate adaptations. An upshift rate change (DRT up) notification is issued by the PPTP xDSL UNI part 1 when the actual data rate exceeds the data rate at the last entry into showtime by more than the threshold. The data rate threshold is coded in bits per second. (R, W, set-by-create) (mandatory for xDSL standards that use this attribute) (4 bytes) + +**Data rate threshold downshift:** This attribute is a threshold on the cumulative data rate downshift achieved over one or more bearer channel data rate adaptations. A downshift rate change (DRT down) notification is issued by the PPTP xDSL UNI part 1 when the actual data rate is below the data rate at the last entry into showtime by more than the threshold. The data rate threshold is coded in bits per second. (R, W, set-by-create) (mandatory for xDSL standards that use this attribute) (4 bytes) + +**Minimum reserved data rate:** This attribute specifies the desired minimum reserved net data rate for the bearer channel. The rate is coded in bits per second. This attribute is needed only if the rate adaptation mode is set to dynamic in the xDSL line configuration profile part 1. (R, W, set-by-create) (optional) (4 bytes) + +**Minimum data rate in low-power state:** This parameter specifies the minimum desired net data rate for the bearer channel during the low-power state (L1/L2). The power management low-power states L1 and L2 are defined in [ITU-T G.992.2] and [ITU-T G.992.3], respectively. The data rate is coded in bits per second. (R, W, set-by-create) (mandatory) (4 bytes) + +**Minimum impulse noise protection:** The $\text{INP}_{\min}$ attribute specifies the minimum INP for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 4.3125 kHz. INP is expressed in DMT symbols with a subcarrier spacing of 4.3125 kHz. It can be $\frac{1}{2}$ symbol or any integer number of symbols from 0 to 16, inclusive. + +If the xTU does not support the configured $\text{INP}_{\min}$ value, it uses the nearest supported INP value greater than $\text{INP}_{\min}$ . + +*Value* $\text{INP}_{\min}$ + +1 0 symbols + +2 $\frac{1}{2}$ symbol + +$N$ $(N - 2)$ symbols, $3 \leq N \leq 18$ + +(R, W, set-by-create) (optional for [ITU-T G.992.1], mandatory for other xDSL standards that use this attribute) (1 byte) + +**Maximum bit error ratio:** This attribute specifies the desired maximum bit error ratio for the bearer channel. It is only valid for [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5]. The bit error ratio is specified via the following values: + +- 1 $10^{-3}$ +- 2 $10^{-5}$ +- 3 $10^{-7}$ + +(R, W, set-by-create) (mandatory for standards that use this attribute) (1 byte) + +**Minimum impulse noise protection 8 kHz:** The INPmin8 attribute specifies the minimum INP for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 8.625 kHz. It is only valid for [ITU-T G.993.2]. INP is expressed in DMT symbols with a subcarrier spacing of 8.625 kHz. It can take any integer value from 0 (default) to 16, inclusive. (R, W) (mandatory for [ITU-T G.993.2]) (1 byte) + +**Maximum delay variation:** The DVMAX attribute specifies the maximum value for delay variation allowed in an OLR procedure. Its value ranges from 1 (0.1 ms) to 254 (25.4 ms). The special value 255 specifies that no delay variation bound is imposed. (R, W) (optional: used by [ITU-T G.993.2]) (1 byte) + +**Channel initialization policy selection:** The CIPOLICY attribute specifies the policy to determine transceiver configuration at initialization. Valid values are 0..1, as defined in the Recommendations that use this attribute. (R, W) (optional) (1 byte) + +**Minimum SOS bit rate downstream:** The MIN-SOS-BR-ds attribute specifies the minimum net data rate required for a valid SOS request in the downstream direction. The value is coded as an unsigned integer representing the data rate as a multiple of 8 kbit/s. (R, W) (optional) (4 bytes) + +**Minimum SOS bit rate upstream:** The MIN-SOS-BR-us attribute specifies the minimum net data rate required for a valid SOS request in the upstream direction. The value is coded as an unsigned integer representing the data rate as a multiple of 8 kbit/s. (R, W) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.7.8 xDSL subcarrier masking downstream profile** + +This ME contains the subcarrier masking downstream profile for an xDSL UNI. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +The four following attributes are bit maps that represent downstream mask values for subcarriers 1..128 (mask 1) through 385..512 (mask 4). The MSB of the first byte corresponds to the lowest + +numbered subcarrier, and the LSB of the last byte corresponds to the highest. Each bit position defines whether the corresponding downstream subcarrier is masked (1) or not masked (0). + +The number of xDSL subcarriers, downstream (NSCds) is the highest numbered subcarrier that can be transmitted in the downstream direction. For [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5], it is defined in the corresponding Recommendation. For [ITU-T G.992.1], NSCds = 256 and for [ITU-T G.992.2], NSCds = 128. + +**Downstream subcarrier mask 1:** Subcarriers 1 to 128. (R, W, set-by-create) (mandatory) (16 bytes) + +**Downstream subcarrier mask 2:** Subcarriers 129 to 256. (R, W) (mandatory for modems that support NSCds > 128) (16 bytes) + +**Downstream subcarrier mask 3:** Subcarriers 257 to 384. (R, W) (mandatory for modems that support NSCds > 256) (16 bytes) + +**Downstream subcarrier mask 4:** Subcarriers 385 to 512. (R, W) (mandatory for modems that support NSCds > 384) (16 bytes) + +**Mask valid:** This Boolean attribute controls and reports the operational status of the downstream subcarrier mask attributes. + +If this attribute is true (1), the downstream subcarrier mask represented in this ME has been impressed on the DSL equipment. + +If this attribute is false (0), the downstream subcarrier mask represented in this ME has not been impressed on the DSL equipment. The default value is false. + +The value of this attribute can be modified by the ONU and OLT, as follows. + +- If the OLT changes any of the four mask attributes or sets mask valid false, then mask valid is false. +- If mask valid is false and the OLT sets mask valid true, the ONU impresses the downstream subcarrier mask data on to the DSL equipment. + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.7.9 xDSL subcarrier masking upstream profile** + +This ME contains the subcarrier masking upstream profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Upstream subcarrier mask:** This attribute is a bit map representing upstream mask values for subcarriers 1 to 64. The MSB of byte 1 corresponds to subcarrier 1, and the + +LSB of byte 8 corresponds to subcarrier 64. Each bit position defines whether the corresponding downstream subcarrier is masked (1) or not masked (0). + +Subcarrier number 1 is the lowest, and the number of xDSL subcarriers, upstream (NSCus) is the highest subcarrier that can be transmitted in the upstream direction. For [ITU-T G.992.3], [ITU-T G.992.4] and [ITU-T G.992.5], it is defined in the corresponding Recommendation. For Annex A of [ITU-T G.992.1] and [ITU-T G.992.2], NSCus = 32 and for Annex B of [ITU-T G.992.1], NSCus = 64. (R, W, set-by-create) (mandatory) (8 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.7.10 xDSL PSD mask profile** + +This ME contains a PSD mask profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**PSD mask table:** This attribute is a table that defines the PSD mask applicable at the U-C2 reference point (downstream) or the U-R2 reference point (upstream). This mask may impose PSD restrictions in addition to the limit PSD mask defined in the relevant Recommendations ([ITU-T G.992.3], [ITU-T G.992.5], [ITU-T G.993.2]). + +NOTE – In [ITU-T G.997.1], this attribute is called PSDMASKds (downstream) and PSDMASKus (upstream). In [ITU-T G.993.2], this attribute is called MIBMASKds (downstream) and MIBMASKus (upstream). The ITU-T G.993.2 MIBMASKus does not include breakpoints to shape US0. + +The PSD mask is specified through a set of breakpoints. Each breakpoint comprises a 2 byte subcarrier index $t$ , with a subcarrier spacing of 4.3125 kHz, and a 1 byte PSD mask level at that subcarrier. The set of breakpoints can then be represented as $[(t_1, \text{PSD}_1), (t_2, \text{PSD}_2), \dots, (t_N, \text{PSD}_N)]$ . The PSD mask level is coded as 0 (0.0 dBm/Hz) to 190 (–95.0 dBm/Hz), in steps of 0.5 dB. + +The maximum number of downstream breakpoints is 32. In the upstream direction, the maximum number of breakpoints is 4 for [ITU-T G.992.3] and 16 for [ITU-T G.993.2]. The requirements for a valid set of breakpoints are defined in the relevant Recommendations ([ITU-T G.992.3], [ITU-T G.992.5], [ITU-T G.993.2]). + +Each table entry in this attribute comprises: + +- an entry number field (1 byte, first entry numbered 1); +- a subcarrier index field, denoted $t$ (2 bytes); +- a PSD mask level field (1 byte). + +By default, the PSD mask table is empty. Setting a subcarrier entry with a valid PSD mask level implies insertion into the table or replacement of an existing entry. Setting an entry's PSD mask level to 0xFF implies deletion from the table. + +(R, W) (mandatory) (4 \* $N$ bytes where $N$ is the number of breakpoints) + +**Mask valid:** This Boolean attribute controls and reports the status of the PSD mask attribute. + +As a status report, the value false indicates that the PSD mask represented in this ME has not been impressed on the DSL equipment. The value true indicates that the PSD mask represented in this ME has been impressed on the DSL equipment. + +This attribute behaves as follows. + +- If the OLT changes any of the PSD mask table entries or sets mask valid false, then mask valid is false. +- If mask valid is false and the OLT sets mask valid true, the ONU impresses the PSD mask data on the DSL equipment. + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.7.11 xDSL downstream RFI bands profile** + +This ME contains the downstream RFI bands profile for an xDSL UNI. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Downstream RFI bands table:** The RFIBANDS attribute is a table where each entry comprises: + +- an entry number field (1 byte, first entry numbered 1); +- subcarrier index 1 field (2 bytes); +- subcarrier index 2 field (2 bytes). + +For [ITU-T G.992.5], this configuration attribute defines the subset of downstream PSD mask breakpoints, as specified in the downstream PSD mask, to be used to notch an RFI band. This subset consists of couples of consecutive subcarrier indices belonging to breakpoints: $[t_i; t_{i+1}]$ , corresponding to the low level of the notch. Interpolation around these points is defined in [ITU-T G.992.5]. + +For [ITU-T G.993.2], this attribute defines the bands where the PSD is to be reduced as specified in clause 7.2.1.2 of [ITU-T G.993.2]. Each band is represented by start and stop subcarrier indices with a subcarrier spacing of 4.3125 kHz. Up to 16 bands may be specified. This attribute defines the RFI bands for both upstream and downstream directions. + +Entries have the default value 0 for both subcarrier index 1 and subcarrier index 2. Setting an entry with a non-zero subcarrier index 1 and subcarrier index 2 implies insertion into the table or replacement of an existing entry. Setting an entry's subcarrier index 1 and subcarrier index 2 to 0 implies deletion from the table, if present. + +(R, W) (mandatory for [ITU-T G.992.5], [ITU-T G.993.2]) (5 \* *N* bytes where *N* is the number of RFI bands) + +**Bands valid:** This Boolean attribute controls and reports the operational status of the downstream RFI bands table. + +If this attribute is true, the downstream RFI bands table has been impressed on the DSL equipment. + +If this attribute is false, the downstream RFI bands table has not been impressed on the DSL equipment. The default value is false. + +This attribute can be modified by the ONU and OLT, as follows. + +- If the OLT changes any of the RFI bands table entries or sets bands valid false, then bands valid is false. +- If bands valid is false and OLT sets bands valid true, the ONU impresses the downstream RFI bands data on to the DSL equipment. + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.7.12 xDSL line inventory and status data part 1** + +This ME contains part 1 of the line inventory and status data for an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a PPTP xDSL UNI part 1. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**xTU-C G.994.1 vendor ID:** This is the vendor ID as inserted by the xTU-C in the ITU-T G.994.1 CL message. It comprises 8 octets, including a country code followed by a (regionally allocated) provider code, as defined in [ITU-T T.35]. (R) (mandatory) (8 bytes) + +- xTU-R G.994.1 vendor ID:** This is the vendor ID as inserted by the xTU-R in the ITU-T G.994.1 CLR message. It comprises 8 binary octets, with the same format as the xTU-C ITU-T G.994.1 vendor ID. (R) (mandatory) (8 bytes) +- xTU-C system vendor ID:** This is the vendor ID as inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises 8 binary octets, with the same format as the xTU-C ITU-T G.994.1 vendor ID. (R) (mandatory) (8 bytes) +- xTU-R system vendor ID:** This is the vendor ID as inserted by the xTU-R in the embedded operations channel and overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises 8 binary octets, with the same format as the xTU-C ITU-T G.994.1 vendor ID. (R) (mandatory) (8 bytes) +- xTU-C version number:** This is the vendor-specific version number as inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4]. It comprises up to 16 binary octets. (R) (mandatory) (16 bytes) +- xTU-R version number:** This is the version number as inserted by the xTU-R in the embedded operations channel of [ITU-T G.992.1] or [ITU-T G.992.2], or the overhead messages of [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2]. The attribute value may be vendor-specific, but is recommended to comprise up to 16 ASCII characters, null-terminated if it is shorter than 16. The string should contain the xTU-R firmware version and the xTU-R model, encoded in that order and separated by a space character: "". It is recognized that legacy xTU-Rs may not support this format. (R) (mandatory) (16 bytes) +- xTU-C serial number part 1:** The vendor-specific serial number inserted by the xTU-C in the overhead messages of [ITU-T G.992.3] and [ITU-T G.992.4] comprises up to 32 ASCII characters, null terminated if it is shorter than 32 characters. This attribute contains the first 16 characters. (R) (mandatory) (16 bytes) +- xTU-C serial number part 2:** This attribute contains the second 16 characters of the xTU-C serial number. (R) (mandatory) (16 bytes) +- xTU-R serial number part 1:** The serial number inserted by the xTU-R in the embedded operations channel of [ITU-T G.992.1] or [ITU-T G.992.2], or the overhead messages of [ITU-T G.992.3], [ITU-T G.992.4], [ITU-T G.992.5] and [ITU-T G.993.2], comprises up to 32 ASCII characters, null-terminated if it is shorter than 32. It is recommended that the equipment serial number, the equipment model and the equipment firmware version, encoded in that order and separated by space characters, be contained: "". It is recognized that legacy xTU-Rs may not support this format. This attribute contains the first 16 characters. (R) (mandatory) (16 bytes) +- xTU-R serial number part 2:** This attribute contains the second 16 characters of the xTU-R serial number. (R) (mandatory) (16 bytes) +- xTU-C self-test results:** This parameter reports the xTU-C self-test result. It is coded in two fields. The most significant octet is 0 if the self-test passed and 1 if it failed. The three least significant octets are a vendor-discretionary integer that can be interpreted in combination with [ITU-T G.994.1] and the system vendor ID. (R) (mandatory) (4 bytes) +- xTU-R self-test results:** This parameter defines the xTU-R self-test result. It is coded in two fields. The most significant octet is 0 if the self-test passed and 1 if it failed. + +The three least significant octets are a vendor-discretionary integer that can be interpreted in combination with [ITU-T G.994.1] and the system vendor ID. (R) (mandatory) (4 bytes) + +**xTU-C transmission system capability:** This attribute lists xTU-C transmission system capabilities. It is a bit map, defined in Table 9.7.12-1. (R) (mandatory) (7 bytes) + +NOTE 1 – This attribute is only 7 bytes long. An eighth byte identifying VDSL2 capabilities is defined in the VDSL2 line inventory and status data part 1 ME. + +**xTU-R transmission system capability:** This attribute lists xTU-R transmission system capabilities. It is a bit map, defined in Table 9.7.12-1. (R) (mandatory) (7 bytes) + +NOTE 2 – This attribute is only 7 bytes long. An eighth byte identifying VDSL2 capabilities is defined in the VDSL2 line inventory and status data part 2 ME. + +**Initialization success/failure cause:** This parameter represents the success or failure cause of the last full initialization performed on the line. It is coded as follows. + +0 Successful + +1 Configuration error + +This error occurs with inconsistencies in configuration parameters, e.g., when the line is initialized in an xDSL transmission system whose xTU does not support the configured maximum delay or the configured minimum or maximum data rate for one or more bearer channels. + +2 Configuration not feasible on the line + +This error occurs if the minimum data rate cannot be achieved on the line with the minimum noise margin, maximum PSD level, maximum delay and maximum bit error ratio for one or more bearer channels. + +3 Communication problem + +This error occurs, for example, due to corrupted messages, bad syntax messages, if no common mode can be selected in the ITU-T G.994.1 handshake procedure or due to a timeout. + +4 No peer xTU detected + +This error occurs if the peer xTU is not powered or not connected or if the line is too long to allow detection of a peer xTU. + +5 Any other or unknown initialization failure cause. + +(R) (mandatory) (1 byte) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +Table 9.7.12-1 describes the xTU transmission system capability attributes in xDSL status MEs. It is a bit map (0 if not allowed, 1 if allowed) with the definition listed in Table 9.7.12-1. + +**Table 9.7.12-1– xTU transmission system table** + +| Bit | Representation | +|----------------|-----------------------------------------------------------------------------------------------------------| +| Octet 1 | | +| 1 (LSB) | [b-ATIS-0600413] | +| 2 | Annex C of [ETSI TS 101 388] | +| 3 | ITU-T G.992.1 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.1]) | +| 4 | ITU-T G.992.1 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.1]) | +| 5 | ITU-T G.992.1 operation over ISDN non-overlapped spectrum (Annex B of [ITU-T G.992.1]) | +| 6 | ITU-T G.992.1 operation over ISDN overlapped spectrum (Annex B of [ITU-T G.992.1]) | +| 7 | ITU-T G.992.1 operation in conjunction with TCM-ISDN non-overlapped spectrum (Annex C of [ITU-T G.992.1]) | +| 8 | ITU-T G.992.1 operation in conjunction with TCM-ISDN overlapped spectrum (Annex C of [ITU-T G.992.1]) | +| Octet 2 | | +| 9 | ITU-T G.992.2 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.2]) | +| 10 | ITU-T G.992.2 operation over POTS overlapped spectrum (Annex B of [ITU-T G.992.2]) | +| 11 | ITU-T G.992.2 operation in conjunction with TCM-ISDN non-overlapped spectrum (Annex C of [ITU-T G.992.2]) | +| 12 | ITU-T G.992.2 operation in conjunction with TCM-ISDN overlapped spectrum (Annex C of [ITU-T G.992.2]) | +| 13 | Reserved | +| 14 | Reserved | +| 15 | Reserved | +| 16 | Reserved | +| Octet 3 | | +| 17 | Reserved | +| 18 | Reserved | +| 19 | ITU-T G.992.3 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.3]) | +| 20 | ITU-T G.992.3 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.3]) | +| 21 | ITU-T G.992.3 operation over ISDN non-overlapped spectrum (Annex B of [ITU-T G.992.3]) | +| 22 | ITU-T G.992.3 operation over ISDN overlapped spectrum (Annex B of [ITU-T G.992.3]) | +| 23 | ITU-T G.992.3 operation in conjunction with TCM-ISDN non-overlapped spectrum (Annex C of [ITU-T G.992.3]) | +| 24 | ITU-T G.992.3 operation in conjunction with TCM-ISDN overlapped spectrum (Annex C of [ITU-T G.992.3]). | +| Octet 4 | | +| 25 | ITU-T G.992.4 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.4]) | +| 26 | ITU-T G.992.4 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.4]) | +| 27 | Reserved | +| 28 | Reserved | +| 29 | ITU-T G.992.3 All digital mode operation with non-overlapped spectrum (Annex I of [ITU-T G.992.3]) | + +**Table 9.7.12-1– xTU transmission system table** + +| Bit | Representation | +|----------------|-------------------------------------------------------------------------------------------------------------------------| +| 30 | ITU-T G.992.3 All digital mode operation with overlapped spectrum (Annex I of [ITU-T G.992.3]) | +| 31 | ITU-T G.992.3 All digital mode operation with non-overlapped spectrum (Annex J of [ITU-T G.992.3]) | +| 32 | ITU-T G.992.3 All digital mode operation with overlapped spectrum (Annex J of [ITU-T G.992.3]) | +| Octet 5 | | +| 33 | ITU-T G.992.4 All digital mode operation with non-overlapped spectrum (Annex I of [ITU-T G.992.4]) | +| 34 | ITU-T G.992.4 All digital mode operation with overlapped spectrum (Annex I of [ITU-T G.992.4]) | +| 35 | ITU-T G.992.3 Reach extended operation over POTS, Mode 1 (non-overlapped, wide upstream) (Annex L of [ITU-T G.992.3]) | +| 36 | ITU-T G.992.3 Reach extended operation over POTS, Mode 2 (non-overlapped, narrow upstream) (Annex L of [ITU-T G.992.3]) | +| 37 | ITU-T G.992.3 Reach extended operation over POTS, Mode 3 (overlapped, wide upstream) (Annex L of [ITU-T G.992.3]) | +| 38 | ITU-T G.992.3 Reach extended operation over POTS, Mode 4 (overlapped, narrow upstream) (Annex L of [ITU-T G.992.3]) | +| 39 | ITU-T G.992.3 Extended upstream operation over POTS non-overlapped spectrum (Annex M of [ITU-T G.992.3]) | +| 40 | ITU-T G.992.3 Extended upstream operation over POTS overlapped spectrum (Annex M of [ITU-T G.992.3]) | +| Octet 6 | | +| 41 | ITU-T G.992.5 operation over POTS non-overlapped spectrum (Annex A of [ITU-T G.992.5]) | +| 42 | ITU-T G.992.5 operation over POTS overlapped spectrum (Annex A of [ITU-T G.992.5]) | +| 43 | ITU-T G.992.5 operation over ISDN non-overlapped spectrum (Annex B of [ITU-T G.992.5]) | +| 44 | ITU-T G.992.5 operation over ISDN overlapped spectrum (Annex B of [ITU-T G.992.5]) | +| 45 | ITU-T G.992.5 operation in conjunction with TCM-ISDN non-overlapped spectrum (Annex C of [ITU-T G.992.5]) | +| 46 | ITU-T G.992.5 operation in conjunction with TCM-ISDN overlapped spectrum (Annex C of [ITU-T G.992.5]) | +| 47 | ITU-T G.992.5 All digital mode operation with non-overlapped spectrum (Annex I of [ITU-T G.992.5]) | +| 48 | ITU-T G.992.5 All digital mode operation with overlapped spectrum (Annex I of [ITU-T G.992.5]) | +| Octet 7 | | +| 49 | ITU-T G.992.5 All digital mode operation with non-overlapped spectrum (Annex J of [ITU-T G.992.5]) | +| 50 | ITU-T G.992.5 All digital mode operation with overlapped spectrum (Annex J of [ITU-T G.992.5]) | +| 51 | ITU-T G.992.5 Extended upstream operation over POTS non-overlapped spectrum (Annex M of [ITU-T G.992.5]) | + +**Table 9.7.12-1– xTU transmission system table** + +| Bit | Representation | +|------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------| +| 52 | ITU-T G.992.5 Extended upstream operation over POTS overlapped spectrum (Annex M of [ITU-T G.992.5]) | +| 53 | Reserved | +| 54 | Reserved | +| 55 | Reserved | +| 56 | Reserved | +| Octet 8 (Note) | | +| 57 | ITU-T G.993.2 region A (North America) (Annex A of [ITU-T G.993.2]) | +| 58 | ITU-T G.993.2 region B (Europe) (Annex B of [ITU-T G.993.2]) | +| 59 | ITU-T G.993.2 region C (Japan) (Annex C of [ITU-T G.993.2]) | +| 60 | Reserved | +| 61 | Reserved | +| 62 | Reserved | +| 63 | Reserved | +| 64 | Reserved | +| NOTE – For backward compatibility reasons, the eighth octet of this table is represented as a separate attribute in separate managed entities. | | + +### 9.7.13 xDSL line inventory and status data part 2 + +This ME contains part 2 of the line inventory and status data for an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a PPTP xDSL UNI part 1. + +NOTE 1 – [ITU-T G.997.1] specifies that bit rate attributes have granularity of 1000 bit/s. If ITU-T G.997.1 compliance is required, the ONU should only report values with this granularity. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**xDSL transmission system:** This parameter defines the transmission system in use. It is a bit map, defined in Table 9.7.12-1. (R) (mandatory) (7 bytes) + +NOTE 2 – This attribute is only 7 bytes long. An eighth byte identifying VDSL2 capabilities in use is defined in the VDSL2 line inventory and status data part 1 ME. + +**Line power management state:** The line has four possible power management states. + +- 0 L0: Synchronized – This line state occurs when the line has full transmission (i.e., showtime). +- 1 L1: Power down data transmission – This line state occurs when there is transmission on the line, but the net data rate is reduced (e.g., only for OAM and higher layer connection and session control). This state applies to [ITU-T G.992.2] only. + +- 2 L2: Power down data transmission – This line state occurs when there is transmission on the line, but the net data rate is reduced (e.g., only for OAM and higher layer connection and session control). This state applies to [ITU-T G.992.3] and [ITU-T G.992.4] only. +- 3 L3: No power – This line state occurs when no power is transmitted on the line at all. + +(R) (mandatory) (1 byte) + +**Downstream line attenuation:** The LATNds attribute is the squared magnitude of the channel characteristics function $H(f)$ averaged over this band, and measured during loop diagnostic mode and initialization. The exact definition is included in the relevant xDSL Recommendation. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB) dB. The special value 0xFFFF indicates that line attenuation is out of range. (R) (mandatory) (2 bytes) + +NOTE 3 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 ME. In an ITU-T G.993.2 context, the downstream line attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. + +**Upstream line attenuation:** The LATNus attribute is the squared magnitude of the channel characteristics function $H(f)$ averaged over this band, and measured during loop diagnostic mode and initialization. The exact definition is included in the relevant xDSL Recommendation. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB). The special value 0xFFFF indicates that line attenuation is out of range. (R) (mandatory) (2 bytes) + +NOTE 4 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 ME. In an ITU-T G.993.2 context, the upstream line attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. + +**Downstream signal attenuation:** The SATNds attribute is the measured difference in the total power transmitted in this band by the xTU-C and the total power received in this band by the xTU-R during loop diagnostic mode, initialization and showtime. The exact definition is included in the relevant xDSL Recommendation. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB). The special value 0xFFFF indicates that signal attenuation is out of range. (R) (mandatory) (2 bytes) + +NOTE 5 – During showtime, only a subset of the subcarriers may be transmitted by the xTU-C, as compared to loop diagnostic mode and initialization. Therefore, the downstream signal attenuation value during showtime may be significantly lower than the downstream signal attenuation value during loop diagnostic mode and initialization. + +NOTE 6 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 ME. In an ITU-T G.993.2 context, the downstream signal attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. + +**Upstream signal attenuation:** The SATNus attribute is the measured difference in decibels in the total power transmitted in this band by the xTU-R and the total power received in this band by the xTU-C during loop diagnostic mode, initialization and showtime. The exact definition is included in the relevant xDSL Recommendation. The attribute value ranges from 0 (0.0 dB) to 1270 (127.0 dB). The special value 0xFFFF indicates that signal attenuation is out of range. (R) (mandatory) (2 bytes) + +NOTE 7 – During showtime, only a subset of the subcarriers may be transmitted by the xTU-R, as compared to loop diagnostic mode and initialization. Therefore, the upstream signal attenuation value during showtime may be significantly lower than the upstream signal attenuation value during loop diagnostic mode and initialization. + +NOTE 8 – [ITU-T G.993.2] specifies a per-band array to represent this attribute. The array is defined in the VDSL2 line inventory and status data part 3 ME. In an ITU-T G.993.2 context, the upstream signal attenuation attribute should be set to 0 here, and populated in the VDSL2 line inventory and status data part 3 ME instead. + +**Downstream SNR ratio margin:** The downstream SNR margin SNRMds is the maximum increase of noise power received at the xTU-R, such that the BER requirements can still be met for all downstream bearer channels. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range (R) (mandatory) (2 bytes) + +**Upstream SNR margin:** The upstream SNR margin SNRMus is the maximum increase of noise power received at the xTU-C, such that the BER requirements can still be met for all upstream bearer channels. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) + +**Downstream maximum attainable data rate:** The ATTNDRds attribute indicates the maximum downstream net data rate currently attainable. The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**Upstream maximum attainable data rate:** The ATTNDRus attribute indicates the maximum upstream net data rate currently attainable. The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**Downstream actual power spectrum density:** The ACTPSDds attribute is the average downstream transmit power spectrum density over the subcarriers in use (subcarriers to which downstream user data are allocated) delivered by the xTU-C at the U-C reference point, at the instant of measurement. The attribute value ranges from 0 (–90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value (0xFFFF) indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**Upstream actual power spectrum density:** The ACTPSDus attribute is the average upstream transmit power spectrum density over the subcarriers in use (subcarriers to which upstream user data are allocated) delivered by the xTU-R at the U-R reference point, at the instant of measurement. The attribute value ranges from 0 (–90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) + +**Downstream actual aggregate transmit power:** The ACTATPds attribute is the total amount of transmit power delivered by the xTU-C at the U-C reference point, at the instant of measurement. The attribute value ranges from 0 (–31.0 dBm) to 620 (+31.0 dBm). The special value (0xFFFF) indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +NOTE 9 – The downstream nominal aggregate transmit power may be taken as a best estimate of the parameter. + +**Upstream actual aggregate transmit power:** The ACTATPus attribute is the total amount of transmit power delivered by the xTU-R at the U-R reference point, at the instant of measurement. The attribute value ranges from 0 (–31.0 dBm) to 620 (+31.0 dBm). The special value (0xFFFF) indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +NOTE 10 – The upstream nominal aggregate transmit power may be taken as a best estimate of the parameter. + +**Initialization – last state transmitted downstream:** This attribute represents the last successful transmitted initialization state in the downstream direction in the last full initialization performed on the line. Initialization states are defined in the individual xDSL Recommendations and are counted from 0 (if [ITU-T G.994.1] is used) or 1 (if [ITU-T G.994.1] is not used) up to showtime. This parameter must be interpreted along with the xDSL transmission system capabilities. + +This parameter is available only when, after a failed full initialization, line diagnostic procedures are activated on the line. Line diagnostic procedures can be activated by the operator of the system (through the loop diagnostics mode forced attribute of the xDSL line configuration profile part 3) or autonomously by the xTU-C or xTU-R. + +(R) (mandatory) (1 byte) + +**Initialization – last state transmitted upstream:** This attribute represents the last successful transmitted initialization state in the upstream direction in the last full initialization performed on the line. Initialization states are defined in the individual xDSL Recommendations and are counted from 0 (if [ITU-T G.994.1] is used) or 1 (if [ITU-T G.994.1] is not used) up to showtime. This parameter must be interpreted along with the xDSL transmission system capabilities. + +This parameter is available only when, after a failed full initialization, line diagnostic procedures are activated on the line. Line diagnostic procedures can be activated by the operator of the system (through the loop diagnostics mode forced attribute of the xDSL line configuration profile part 3) or autonomously by the xTU-C or xTU-R. + +(R) (mandatory) (1 byte) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.7.14 xDSL line inventory and status data part 3** + +This ME extends the attributes defined in the xDSL line inventory and status data parts 1 and 2. This ME reports downstream attributes. + +#### *Relationships* + +This is one of the status MEs associated with an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**TSSpsds table:** This table contains downstream transmit spectrum shaping attributes expressed as the set of breakpoints exchanged during [ITU-T G.994.1]. Each breakpoint consists of a 2 byte subcarrier index and the associated shaping attribute. The shaping attribute is 1 byte, an integer value in the 0 to 126 range, represented as a multiple of $-0.5$ dB. The special value 127 indicates that the subcarrier is not transmitted. (R) (mandatory) $(3 * N)$ bytes, where $N$ is the number of breakpoints) + +**HLINSCds:** This attribute is the scale factor to be applied to the downstream $H_{\text{lin}}(f)$ values. It is coded as a 16 bit unsigned integer. This attribute is only available after a loop diagnostic procedure. (R) (mandatory) (2 bytes) + +**HLINpsds table:** This attribute is an array of complex coefficients $\{a, b\}$ that represent the downstream transfer function $H_{\text{lin}}(f)$ in linear form. Each array entry represents $H_{\text{lin}}(f) = i * \text{HLINGds} * \Delta f$ for a particular subcarrier group index $i$ , ranging from 0 to $\min(\text{NSds}, 511)$ . $H_{\text{lin}}(f)$ may be reconstructed from the array as $((\text{HLINSCds}/2^{15}) * ((a(i) + j * b(i))/2^{15}))$ , where $a(i)$ and $b(i)$ are 2s complement integers in the range $(-2^{15} + 1)$ to $(+2^{15} - 1)$ . The granularity of $a$ and $b$ depends on the scale factor. + +The special value $a(i) = b(i) = -2^{15}$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the attenuation is out of the range to be represented. + +This attribute is only available after a loop diagnostic procedure. (R) (mandatory) $(4 * N)$ bytes, where $N$ is the number of subcarrier groups) + +**HLOGMTds:** After a loop diagnostic procedure, this attribute contains the number of symbols used to measure the downstream $H_{\text{log}}(f)$ values. It is a 16 bit unsigned value that corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**HLOGpsds table:** The HLOGpsds attribute contains an array of numbers $m(i)$ , where $i$ is a particular subcarrier group index, ranging from 0 to $\min(\text{NSds}, 511)$ , and $m$ lies in the range 0..1022, with a granularity of 0.1 dB. The downstream transfer function $H_{\text{log}}(f)$ can be reconstructed by the OLT management client as $(6 - m(i)/10)$ dBm/Hz, with a range from +6 to approximately $-96$ dBm/Hz. + +The special value $m = 1023$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the attenuation is out of range to be represented. + +(R) (mandatory) $(2 * N)$ bytes, where $N$ is the number of subcarrier groups) + +**QLNMTds:** After a loop diagnostic procedure, the quiet line noise (QLN) PSD measurement time attribute contains the number of symbols used to measure the downstream QLN( $f$ ) values. It is a 16 bit unsigned value that corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**QLNpsds table:** The QLN PSD attribute contains an array of numbers $n(i)$ , where $i$ is a subcarrier group index, ranging from 0 to $\min(\text{NSds}, 511)$ , and $n$ lies in the range 0..254, with a granularity of 0.5 dB. The downstream QLN( $f$ ) can be reconstructed by the OLT management client as $(-23 - n(i)/2)$ dBm/Hz, with a range from $-150$ to $-23$ dBm/Hz. + +The special value $n = 255$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the noise PSD is out of range to be represented. + +(R) (mandatory) (N bytes, where N is the number of subcarrier groups) + +**SNRMTds:** After a loop diagnostic procedure, the SNR measurement time attribute contains the number of symbols used to measure the downstream SNR(f) values. It is a 16 bit unsigned value that corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**SNRpsds table:** The SNRpsds attribute contains an array of numbers $\text{snr}(i)$ , where $i$ is a subcarrier group index, ranging from 0 to $\min(\text{NSds}, 511)$ , and $\text{snr}$ lies in the range 0..254, with a granularity of 0.5 dB. The downstream SNR function $\text{SNR}(f)$ can be reconstructed by the OLT management client as $(-32 + \text{snr}(i)/2)$ dBm/Hz, with a range from $-160$ to $-32$ dBm/Hz. + +The special value $\text{snr} = 255$ indicates that no measurement could be done for this subcarrier group because it is out of the passband or that the noise PSD is out of range to be represented. + +(R) (mandatory) (N bytes, where N is the number of subcarrier groups) + +**BITSpsds table:** This attribute reports the downstream bits allocation table per subcarrier. It is an array of values in the range 0..15 for subcarriers 0..NSds. Entries for subcarriers out of the downstream medley set are set to 0. (R) (mandatory) (N bytes, where N is the number of subcarriers) + +**GAINpsds table:** This attribute contains the downstream gain allocation table per subcarrier. It is an array of integer values in the range 0..4093 for subcarriers 0..NSds. The gain is represented as a multiple of 1/512 on a linear scale. Entries for subcarriers out of the downstream medley set are set to 0. (R) (mandatory) (2N bytes, where N is the number of subcarriers) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.15 xDSL line inventory and status data part 4** + +This ME extends the attributes defined in the xDSL line inventory and status data parts 1, 2 and 3. This ME reports upstream attributes. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**TSSpsus table:** This attribute contains the upstream transmit spectrum shaping attributes, expressed as the set of breakpoints exchanged during [ITU-T G.994.1]. Each + +breakpoint consists of a 2 byte subcarrier index and the associated shaping attribute. The shaping attribute is one byte, a value in the range 0..126, representing a multiple of $-0.5$ dB. The special value 127 indicates that the subcarrier is not transmitted. (R) (mandatory) $(3 * N$ bytes, where $N$ is the number of breakpoints) + +**HLINSCus:** This attribute is a 16 bit unsigned integer, the scale factor to be applied to the upstream $H_{\text{lin}}(f)$ values. It is only available after a loop diagnostic procedure. (R) (mandatory) (2 bytes) + +**HLINpsus table:** This attribute is an array of complex upstream $H_{\text{lin}}(f)$ values in linear scale. It is coded in the same way as the related downstream attribute HLINpsds (see xDSL line inventory and status data part 3). This attribute is only available after a loop diagnostic procedure. (R) (mandatory) $(4N$ bytes, where $N$ is the number of subcarrier groups) + +**HLOGMTus:** After a loop diagnostic procedure, this attribute contains the number of symbols used to measure the upstream $H_{\text{log}}(f)$ values. Its value corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**HLOGpsus table:** This attribute is an array of real upstream $H_{\text{log}}(f)$ values. It is coded in the same way as the related downstream attribute HLOGpsds (see xDSL line inventory and status data part 3). (R) (mandatory) $(2 * N$ bytes, where $N$ is the number of subcarrier groups) + +**QLNMTus:** After a loop diagnostic procedure, the QLN PSD measurement attribute contains the number of symbols used to measure the upstream $QLN(f)$ values. Its value corresponds to the value specified in the governing Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**QLNpsus table:** The QLN attribute represents an array of real upstream $QLN(f)$ values. It is coded in the same way as the related downstream attribute QLNpsds (see xDSL line inventory and status data part 3). (R) (mandatory) $(N$ bytes, where $N$ is the number of subcarrier groups) + +**SNRMTus:** After a loop diagnostic procedure, the SNR measurement time attribute reports the number of symbols used to measure the upstream $SNR(f)$ values. Its value corresponds to the value specified in the governing Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) + +**SNRpsus table:** This attribute is an array of real upstream $SNR(f)$ values. It is coded in the same way as the related downstream attribute SNRpsds (see xDSL line inventory and status data part 3). (R) (mandatory) $(N$ bytes, where $N$ is the number of subcarrier groups) + +**BITSpsus table:** This attribute contains the upstream bits allocation table per subcarrier. It is an array in the range 0..15 for subcarriers $0..N_{\text{sus}}$ . Entries for subcarriers out of the upstream medley set are set to 0. (R) (mandatory) $(N$ bytes, where $N$ is the number of subcarriers) + +**GAINpsus table:** This attribute contains the upstream gains allocation table per subcarrier. It is an array in the range 0..4093 for subcarriers $0..N_{\text{sus}}$ . The gain is represented as a multiple of $1/512$ on a linear scale. Entries for subcarriers out of the upstream medley set are set to 0. (R) (mandatory) $(2 * N$ bytes, where $N$ is the number of subcarriers) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.16 VDSL2 line inventory and status data part 1** + +This ME extends the xDSL line configuration MEs. The ME name was chosen because its attributes were initially unique to ITU-T G.993.2 VDSL2. Due to continuing standards development, some attributes – and therefore this ME – have also become applicable to other Recommendations, specifically [ITU-T G.992.3] and [ITU-T G.992.5]. + +This ME contains general and downstream attributes. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. It is meaningful if the PPTP supports [ITU-T G.992.3], [ITU-T G.992.5] or [ITU-T G.993.2]. The ONU automatically creates or deletes an instance of this ME upon creation and deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**VDSL2 transmission system capability xTU-C:** This attribute extends the xTU-C transmission system capability attribute of the xDSL line inventory and status data part 1 to include xTU-C VDSL2 capabilities. It is defined by bits 57..64 of Table 9.7.12-1. (R) (mandatory) (1 byte) + +**VDSL2 transmission system:** This attribute reports the transmission system in use. It extends the xDSL transmission system attribute of the xDSL line inventory and status data part 2 ME with a byte that includes VDSL2 capabilities currently in use. It is defined by bits 57..64 of Table 9.7.12-1. (R) (mandatory) (1 byte) + +**VDSL2 profile:** This attribute identifies the profile in use. It is a bit map (0 if not allowed, 1 if allowed) with the following definition: + +| Bit | Meaning | +|------------|---------------------------| +| 1 (LSB) | ITU-T G.993.2 profile 8a | +| 2 | ITU-T G.993.2 profile 8b | +| 3 | ITU-T G.993.2 profile 8c | +| 4 | ITU-T G.993.2 profile 8d | +| 5 | ITU-T G.993.2 profile 12a | +| 6 | ITU-T G.993.2 profile 12b | +| 7 | ITU-T G.993.2 profile 17a | +| 8 | ITU-T G.993.2 profile 30a | + +(R) (mandatory) (1 byte) + +**VDSL2 limit PSD mask and bandplan:** This attribute defines the limit PSD mask and band plan in use. It is a bit map as defined by Table 9.7.6-1. (R) (mandatory) (8 bytes) + +**VDSL2 US0 PSD mask:** This attribute defines the US0 PSD mask in use. It is a bit map as defined by Table 9.7.6-2. (R) (mandatory) (4 bytes) + +**ACTSNRMODEds:** This attribute indicates whether transmitter-referred virtual noise is active on the line in the downstream direction. + +- 1 Virtual noise inactive +- 2 Virtual noise active + +(R) (mandatory) (1 byte) + +The following four attributes have similar definitions. In each case, valid attribute values are 1, 2, 4, 8. In ADSL applications, the corresponding value is fixed at 1, and therefore need not be specified. For VDSL2, it is equal to the size of the subcarrier group used to compute these attributes (see clause 11.4.1 of [ITU-T G.993.2]). + +**HLINGds:** This attribute contains the number of subcarriers per group used to report HLINpsds. (R) (mandatory) (1 byte) + +**HLOGGds:** This attribute contains the number of subcarriers per group used to report HLOGpsds. (R) (mandatory) (1 byte) + +**QLNGds:** This attribute contains the number of subcarriers per group used to report QLNpsds. (R) (mandatory) (1 byte) + +**SNRGds:** This attribute contains the number of subcarriers per group used to report SNRpsds. (R) (mandatory) (1 byte) + +**MREFPSDds table:** The downstream medley reference PSD table contains the set of breakpoints exchanged in the MREFPSDds fields of the O-PRM message of [ITU-T G.993.2]. + +The format is similar to that specified for the PSD descriptor in [ITU-T G.993.2]. In [ITU-T G.993.2], the first byte gives the size of the table, each entry of which is 3 bytes. In the OMCI definition, the first byte is omitted because the size of the table is known from the response to the get command. + +(R) (mandatory) ( $3 * N$ bytes, where $N$ is the number of breakpoints) + +**TRELLISds:** This attribute reports whether trellis coding is in use in the downstream direction. + +- 0 Trellis not used +- 1 Trellis used + +(R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual rate adaptation mode downstream:** The ACT-RA-MODEds attribute indicates the actual active RA mode in the downstream direction. + +- 1 MANUAL +- 2 AT\_INIT +- 3 DYNAMIC +- 4 DYNAMIC with SOS ([ITU-T G.993.2] only) + +(R) (optional) (1 byte) + +**Actual impulse noise protection robust operations channel (ROC) downstream:** The ACTINP-ROC-ds attribute reports the actual INP of the ROC in the downstream direction expressed in multiples of $T_{4k}$ . The INP of this attribute + +is equal to the integer value multiplied by 0.1 symbols. Valid values and usage are given in clause 7.5.1.34.1 of [ITU-T G.997.1]. (R) (optional) (1 byte) + +**SNR margin ROC downstream:** The SNRM-ROC-ds attribute reports the actual signal-to-noise margin of the ROC in the downstream direction. Its value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (optional) (2 bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.17 VDSL2 line inventory and status data part 2** + +This ME extends the xDSL line configuration MEs. The ME name was chosen because its attributes were initially unique to ITU-T G.993.2 VDSL2. Due to continuing standards development, some attributes – and therefore this ME – have also become applicable to other Recommendations, specifically [ITU-T G.992.3] and [ITU-T G.992.5]. + +This ME contains upstream attributes. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. It is meaningful if the PPTP supports [ITU-T G.992.3], [ITU-T G.992.5] or [ITU-T G.993.2]. The ONU automatically creates or deletes an instance of this ME upon creation and deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**VDSL2 transmission system capability xTU-R:** This attribute extends the xTU-R transmission system capability attribute of the xDSL line inventory and status data part 1 to include xTU-R VDSL2 capabilities. It is defined by bits 57..64 of Table 9.7.12-1. (R) (mandatory) (1 byte) + +**ACTSNRMODEus:** This attribute indicates whether transmitter-referred virtual noise is active on the line in the upstream direction. + +- 1 Virtual noise inactive +- 2 Virtual noise active + +(R) (mandatory) (1 byte) + +**UPBOKLE:** This attribute contains the electrical length estimated by the VTU-O expressed in decibels at 1 MHz, $k l_0$ (see O-UPDATE in clause 12.3.3.2.1.2 of [ITU-T G.993.2]). This is the final electrical length that would have been sent from the VTU-O to the VTU-R if the electrical length were not forced by the OLT. The value lies in the range 0 (0.0 dB) to 1280 (128.0 dB) (R) (mandatory) (2 bytes) + +The following four attributes have similar definitions. In each case, valid attribute values are 1, 2, 4, 8. In ADSL applications, the corresponding value is fixed at 1, and therefore need not be specified. For VDSL2, it is equal to the size of the subcarrier group used to compute these attributes (see clause 11.4.1 of [ITU-T G.993.2]). + +- HLINGus:** This attribute is the number of subcarriers per group used to report HLINpsus. (R) (mandatory) (1 byte) +- HLOGGus:** This attribute is the number of subcarriers per group used to report HLOGpsus. (R) (mandatory) (1 byte) +- QLNGus:** This attribute is the number of subcarriers per group used to report QLNpsus. (R) (mandatory) (1 byte) +- SNRGus:** This attribute is the number of subcarriers per group used to report SNRpsus. (R) (mandatory) (1 byte) +- MREFPSDus table:** The upstream medley reference PSD attribute contains the set of breakpoints exchanged in the MREFPSDus fields of the R-PRM message of [ITU-T G.993.2]. +- The format is similar to that specified for the PSD descriptor in [ITU-T G.993.2]. In [ITU-T G.993.2], the first byte gives the size of the table, each entry of which is 3 bytes. In the OMCI definition, the first byte is omitted because the size of the table is known from the response to the get command. +- (R) (mandatory) ( $3 * N$ bytes, where $N$ is the number of breakpoints) +- TRELLISus:** This attribute reports whether trellis coding is in use in the upstream direction. +- 0 Trellis not used + - 1 Trellis used +- (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) +- ACTUALCE:** This attribute reports the cyclic extension used on the line. It is coded as an unsigned integer from 2 to 16 in units of $N/32$ samples, where $2N$ is the IDFT size. (R) (mandatory) (1 byte) +- UPBOKLE-R:** This attribute contains the electrical length estimated by the VTU-R expressed in decibels at 1 MHz. This is the value contained in the message R-MSG1 (see clause 12.3.3.2.2.1 of [ITU-T G.993.2]). Its value lies in the range 0 (0.0 dB) to 1280 (128.0 dB) (R) (optional) (2 bytes) +- Actual rate adaptation mode upstream:** The ACT-RA-MODEus attribute indicates the actual active RA mode in the upstream direction. +- 1 MANUAL + - 2 AT\_INIT + - 3 DYNAMIC + - 4 DYNAMIC with SOS ([ITU-T G.993.2] only) +- (R) (optional) (1 byte) +- Actual impulse noise protection ROC upstream:** The ACTINP-ROC-us attribute reports the actual INP of the ROC in the upstream direction expressed in multiples of $T_{4k}$ . The INP of this attribute is equal to the integer value multiplied by 0.1 symbols. Valid values and usage are given in clause 7.5.1.34.2 of [ITU-T G.997.1]. (R) (optional) (1 byte) +- SNR margin ROC upstream:** The SNRM-ROC-us attribute reports the actual signal-to-noise margin of the ROC in the upstream direction. Its value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (optional) (2 bytes) + +#### Actions + +Get, get next + +#### *Notifications* + +None. + +### **9.7.18 VDSL2 line inventory and status data part 3** + +This ME extends the other xDSL line inventory and status data MEs with attributes specific to VDSL2. This ME contains per-band attributes for both directions. These same attributes are defined in the xDSL line inventory and status data part 2 ME, but only for a single band. [ITU-T G.993.2] allows for VDSL2 to have as many as five bands upstream and as many as five bands downstream. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. It is required only if VDSL2 is supported by the PTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**Upstream bands count:** This attribute reports the number of upstream bands. It can be used to filter the upstream attributes. All upstream attributes are arrays of per-band entries, of which the first upstream bands count are populated. The contents of the arrays for unused frequency bands are unspecified. The original attributes were allocated for as many as four upstream bands, US0, 1, 2, 3; optional extended attributes have been added to accommodate the possibility that five upstream bands may be needed. (R) (mandatory) (1 byte) + +**Downstream bands count:** This attribute reports the number of downstream bands. It can be used to filter the downstream attributes. All downstream attributes are arrays of per-band entries, of which the first downstream bands count are populated. The contents of the arrays for unused frequency bands are unspecified. The original attributes were allocated for as many as three downstream bands, DS1, 2, 3; optional extended attributes have been added to accommodate the possibility that five downstream bands may be needed. (R) (mandatory) (1 byte) + +**Downstream line attenuation per band:** The LATNd attribute is defined per usable band. It is the squared magnitude of the channel characteristics function, $H(f)$ , averaged over this band, and measured during loop diagnostic mode and initialization. The exact definition is included in the relevant xDSL Recommendation. The upstream line attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates that the line attenuation per band is out of the range to be represented. (R) (mandatory) (3 bands \* 2 bytes = 6 bytes) + +**Upstream line attenuation per band:** The LATNu attribute is defined per usable band. It is the squared magnitude of the channel characteristics function $H(f)$ averaged over this band, and measured during loop diagnostic mode and initialization. The exact definition is included in the relevant xDSL Recommendation. The upstream line attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates that line attenuation per band is out of range to be represented. (R) (mandatory) (4 bands \* 2 bytes = 8 bytes) + +**Downstream signal attenuation per band:** The SATNd attribute is defined per usable band. It is the measured difference in the total power transmitted in this band by the + +xTU-C and the total power received by the xTU-R during loop diagnostic mode, initialization and showtime. The exact definition is included in the relevant xDSL Recommendation. The downstream signal attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates that the signal attenuation per band is out of the range to be represented. (R) (mandatory) (3 bands \* 2 bytes = 6 bytes) + +NOTE 1 – During showtime, only a subset of the subcarriers may be transmitted by the xTU-C, as compared to loop diagnostic mode and initialization. Therefore, the downstream signal attenuation value during showtime may be significantly lower than the downstream signal attenuation value during loop diagnostic mode and initialization. + +**Upstream signal attenuation per band:** The SATNus attribute is defined per usable band. It is the measured difference in decibels in the total power transmitted in this band by the xTU-R and the total power received in this band by the xTU-C during loop diagnostic mode, initialization and showtime. The exact definition is included in the relevant xDSL Recommendation. The upstream signal attenuation per band ranges from 0 (0.0 dB) to 1270 (+127.0 dB). The special value 0xFFFF indicates the signal attenuation per band is out of range to be represented. (R) (mandatory) (4 bands \* 2 bytes = 8 bytes) + +NOTE 2 – During showtime, only a subset of the subcarriers may be transmitted by the xTU-R, as compared to loop diagnostic mode and initialization. Therefore, the upstream signal attenuation value during showtime may be significantly lower than the upstream signal attenuation value during loop diagnostic mode and initialization. + +**Downstream SNR margin per band:** The SNRMpbds attribute is defined per usable band. The downstream SNR margin per band is the maximum increase of noise power received at the xTU-R, such that the BER requirements are met for all downstream bearer channels. Each array value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range to be represented. (R) (mandatory) (3 bands \* 2 bytes = 6 bytes) + +**Upstream SNR margin per band:** The SNRMpbus attribute is defined per usable band. The upstream SNR margin per band is the maximum increase of noise power received at the xTU-C, such that the BER requirements are met for all upstream bearer channels. Each array value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range to be represented. (R) (mandatory) (4 bands \* 2 bytes = 8 bytes) + +**Downstream line attenuation extension:** This attribute extends LATNds when more than three downstream bands are used. It is defined in the same way as the downstream line attenuation per band attribute. (R) (optional) (2 bands \* 2 bytes = 4 bytes) + +**Upstream line attenuation extension:** This attribute extends LATNus when more than four upstream bands are used. It is defined in the same way as the upstream line attenuation per band attribute. (R) (optional) (1 band \* 2 bytes = 2 bytes) + +**Downstream signal attenuation extension:** This attribute extends SATNds when more than three downstream bands are used. It is defined in the same way as the downstream signal attenuation per band attribute. (R) (optional) (2 bands \* 2 bytes = 4 bytes) + +**Upstream signal attenuation extension:** This attribute extends SATNus when more than four upstream bands are used. It is defined in the same way as the upstream signal attenuation per band attribute. (R) (optional) (1 band \* 2 bytes = 2 bytes) + +**Downstream SNR margin extension:** This attribute extends SNRMpbds when more than three downstream bands are used. It is defined in the same way as the downstream SNR margin per band attribute. (R) (optional) (2 bands \* 2 bytes = 4 bytes) + +**Upstream SNR margin extension:** This attribute extends SNRMpbus when more than four upstream bands are used. It is defined in the same way as the upstream SNR margin per band attribute. (R) (optional) (1 band \* 2 bytes = 2 bytes) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.7.19 xDSL channel downstream status data** + +This ME contains downstream channel status data for an xDSL UNI. The ONU automatically creates or deletes instances of this ME upon the creation or deletion of a PPTP xDSL UNI part 1. + +NOTE – [ITU-T G.997.1] specifies that bit rate attributes have a granularity of 1000 bit/s. If ITU-T G.997.1 compliance is required, the ONU should only report values with this granularity. + +#### *Relationships* + +One or more instances of this ME are associated with an instance of an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Actual interleaving delay:** This attribute is the actual one-way interleaving delay introduced by the PMS-TC between the alpha and beta reference points, excluding delay in the L1 and L2 states. In the L1 and L2 states, the attribute contains the interleaving delay in the previous L0 state. For ADSL, this attribute is derived from the *S* and *D* attributes as $\text{cap}(S*D)/4$ ms, where *S* is the number of symbols per codeword, *D* is the interleaving depth and $\text{cap}()$ denotes rounding to the next higher integer. For [ITU-T G.993.2], this attribute is computed according to the formula in clause 9.7 of [ITU-T G.993.2]. The actual interleaving delay is coded in milliseconds, rounded to the nearest millisecond. (R) (mandatory) (1 byte) + +**Actual data rate:** This parameter reports the actual net data rate of the bearer channel, excluding the rate in the L1 and L2 states. In the L1 or L2 state, the parameter contains the net data rate in the previous L0 state. The data rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**Previous data rate:** This parameter reports the previous net data rate of the bearer channel just before the latest rate change event occurred, excluding transitions between the L0 state and the L1 or L2 states. A rate change can occur at a power management state transition, e.g., at full or short initialization, fast retrain or power down, or at a dynamic rate adaptation. The rate is coded in bits per second (R) (mandatory) (4 bytes) + +**Actual impulse noise protection:** The ACTINP attribute reports the actual INP on the bearer channel in the L0 state. In the L1 or L2 state, the attribute contains the INP in + +the previous L0 state. The value of this attribute is a number of DMT symbols, with a granularity of 0.1 symbols. Its range is from 0 (0.0 symbols) to 254 (25.4 symbols). The special value 255 indicates an ACTINP higher than 25.4. (R) (optional for [ITU-T G.992.1], mandatory for other xDSL Recommendations that support this attribute) (1 byte) + +**Actual size of Reed-Solomon codeword:** The NFEC attribute reports the actual Reed-Solomon codeword size used in the latency path in which the bearer channel is transported. The value is coded in bytes, and ranges from 0..255. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual number of Reed-Solomon redundancy bytes:** The RFEC attribute reports the actual number of Reed-Solomon redundancy bytes per codeword used in the latency path in which the bearer channel is transported. The value is coded in bytes, and ranges from 0..16. The value 0 indicates no Reed-Solomon coding. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual number of bits per symbol:** The LSYMB attribute reports the actual number of bits per symbol assigned to the latency path in which the bearer channel is transported, excluding trellis overhead. The value is coded in bits, and ranges from 0..65535. (R) (mandatory for [ITU-T G.993.2 VDSL2, optional for others) (2 bytes) + +**Actual interleaving depth:** The INTLVDEPTH attribute reports the actual depth of the interleaver used in the latency path in which the bearer channel is transported. The value ranges from 1..4096 in steps of 1. The value 1 indicates no interleaving. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (2 bytes) + +**Actual interleaving block length:** The INTLVBLOCK attribute reports the actual block length of the interleaver used in the latency path in which the bearer channel is transported. The value ranges from 4..255 in steps of 1. (R) (mandatory for ITU-T G.993.2 VDSL2, undefined for others) (1 byte) + +**Actual latency path:** The LPATH attribute reports the index of the actual latency path in which the bearer channel is transported. Valid values are 0..3. In [ITU-T G.992.1], the fast path is mapped to latency index 0; the interleaved path to index 1. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual impulse noise protection against repetitive electrical impulse noise (ACTINP\_REIN):** If retransmission is used in a given transmit direction, this parameter reports the actual INP against REIN on the bearer channel. The INP of this attribute is equal to the integer value multiplied by 0.1 symbols. Valid values and usage are given in clause 7.5.2.9 of [ITU-T G.997.1] (R) (optional) (1 byte) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.7.20 xDSL channel upstream status data** + +This ME contains upstream channel status data for an xDSL UNI. The ONU automatically creates or deletes instances of this ME upon the creation or deletion of a PPTP xDSL UNI part 1. + +#### Relationships + +One or more instances of this ME are associated with an instance of an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Actual interleaving delay:** This attribute is the actual one-way interleaving delay introduced by the PMS-TC between the alpha and beta reference points, excluding the L1 and L2 states. In the L1 and L2 states, this attribute contains the interleaving delay in the previous L0 state. For ADSL, this attribute is derived from the *S* and *D* attributes as $\text{cap}(S*D)/4$ ms, where *S* is the number of symbols per codeword, *D* is the interleaving depth and $\text{cap}()$ denotes rounding to the next higher integer. For [ITU-T G.993.2], this attribute is computed according to the formula in clause 9.7 of [ITU-T G.993.2]. The actual interleaving delay is coded in milliseconds, rounded to the nearest millisecond. (R) (mandatory) (1 byte) + +**Actual data rate:** This parameter reports the actual net data rate of the bearer channel, excluding the L1 and L2 states. In the L1 or L2 state, the parameter contains the net data rate in the previous L0 state. The data rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**Previous data rate:** This parameter reports the previous net data rate of the bearer channel just before the latest rate change event occurred, excluding transitions between the L0 state and the L1 or L2 state. A rate change can occur at a power management state transition, e.g., at full or short initialization, fast retrain or power down, or at a dynamic rate adaptation. The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**Actual impulse noise protection:** The ACTINP attribute reports the actual INP on the bearer channel in the L0 state. In the L1 or L2 state, the attribute contains the INP in the previous L0 state. The value is coded in fractions of DMT symbols with a granularity of 0.1 symbols. The range is from 0 (0.0 symbols) to 254 (25.4 symbols). The special value 255 indicates an ACTINP higher than 25.4. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for other xDSL Recommendations that support it) (1 byte) + +**Impulse noise protection reporting mode:** The INPREPORT attribute reports the method used to compute the ACTINP. If set to 0, the ACTINP is computed according to the $\text{INP\_no\_erasure}$ formula (clause 9.6 of [ITU-T G.993.2]). If set to 1, ACTINP is the value estimated by the xTU receiver. (R) (mandatory for ITU-T G.993.2 VDSL2) (1 byte) + +**Actual size of Reed-Solomon codeword:** The NFEC attribute reports the actual Reed-Solomon codeword size used in the latency path in which the bearer channel is transported. Its value is coded in bytes in the range 0..255. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual number of Reed-Solomon redundancy bytes:** The RFEC attribute reports the actual number of Reed-Solomon redundancy bytes per codeword used in the latency path in which the bearer channel is transported. Its value is coded in bytes in the range 0..16. The value 0 indicates no Reed-Solomon coding. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual number of bits per symbol:** The LSYMB attribute reports the actual number of bits per symbol assigned to the latency path in which the bearer channel is transported, excluding trellis overhead. Its value is coded in bits in the range 0..65535. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (2 bytes) + +**Actual interleaving depth:** The INTLVDEPTH attribute reports the actual depth of the interleaver used in the latency path in which the bearer channel is transported. Its value ranges from 1..4096 in steps of 1. The value 1 indicates no interleaving. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (2 bytes) + +**Actual interleaving block length:** The INTLVBLOCK attribute reports the actual block length of the interleaver used in the latency part in which the bearer channel is transported. Its value ranges from 4..255 in steps of 1. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +**Actual latency path:** The LPATH attribute reports the index of the actual latency path in which the bearer channel is transported. Valid values are 0..3. In [ITU-T G.992.1], the fast path is mapped to latency index 0; the interleaved path to index 1. (R) (mandatory for ITU-T G.993.2 VDSL2, optional for others) (1 byte) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.7.21 xDSL xTU-C performance monitoring history data part 1** + +This ME collects PM data on the xTU-C to xTU-R path as seen from the xTU-C. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Loss of frame seconds:** (R) (mandatory) (2 bytes) + +**Loss of signal seconds:** (R) (mandatory) (2 bytes) + +**Loss of link seconds:** (R) (mandatory) (2 bytes) + +**Loss of power seconds:** (R) (mandatory) (2 bytes) + +**Errored seconds (ES):** This attribute counts 1 s intervals with one or more CRC-8 anomalies summed over all received bearer channels, or one or more loss of signal (LOS) defects, or one or more SEF defects, or one or more LPR defects. (R) (mandatory) (2 bytes) + +**Severely errored seconds:** This attribute counts severely errored seconds (SES-L). An SES is declared if, during a 1 s interval, there were 18 or more CRC-8 anomalies in one or more of the received bearer channels, or one or more LOS defects, or one or more SEF defects, or one or more LPR defects. + +If the relevant Recommendation ([ITU-T G.992.3], [ITU-T G.992.5] or [ITU-T G.993.2]) supports a 1 s normalized CRC-8 anomaly counter increment, the 1 s SES counter follows this value instead of counting CRC-8 anomalies directly. + +If a common CRC is applied over multiple bearer channels, then each related CRC-8 anomaly is counted only once for the whole set of bearer channels over which the CRC is applied. + +(R) (mandatory) (2 bytes) + +**Line initializations:** This attribute counts the total number of full initializations attempted on the line, both successful and failed. (R) (mandatory) (2 bytes) + +**Failed line initializations:** This attribute counts the total number of failed full initializations during the accumulation period. A failed full initialization occurs when showtime is not reached at the end of the full initialization procedure. (R) (mandatory) (2 bytes) + +**Short initializations:** This attribute counts the total number of fast retrains or short initializations attempted on the line, successful and failed. Fast retrain is defined in [ITU-T G.992.2]. Short initialization is defined in [ITU-T G.992.3] and [ITU-T G.992.4]. (R) (optional) (2 bytes) + +**Failed short initializations:** This attribute counts the total number of failed fast retrains or short initializations during the accumulation period, e.g., when: + +- a CRC error is detected; +- a timeout occurs; +- a fast retrain profile is unknown. + +(R) (optional) (2 bytes) + +**FEC seconds:** This attribute counts seconds during which at least one uncorrectable FEC codeword was received. (R) (mandatory) (2 bytes) + +**Unavailable seconds:** This attribute counts 1 s intervals during which the xDSL UNI is unavailable. The line becomes unavailable at the onset of 10 contiguous SES-Ls. The 10 SES-Ls are included in unavailable time. Once unavailable, the line becomes available at the onset of 10 contiguous seconds that are not severely errored. The 10 s with no SES-Ls are excluded from unavailable time. Some attribute counts are inhibited during unavailability – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (mandatory) (2 bytes) + +**SOS success count, near end:** The SOS-SUCCESS-NE attribute is a count of the total number of successful SOS procedures initiated by the near-end xTU on the line during the accumulation period. Successful SOS is defined in clause 12.1.4 of [ITU-T G.993.2]. (R) (optional) (2 bytes) + +**SOS success count, far end:** The SOS-SUCCESS-FE attribute is a count of the total number of successful SOS procedures initiated by the far-end xTU on the line during the accumulation period. Successful SOS is defined in clause 12.1.4 of [ITU-T G.993.2]. (R) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------|------------------------------|-----------------------------------------| +| 0 | Loss of frame seconds | 1 | +| 1 | Loss of signal seconds | 2 | +| 2 | Loss of link seconds | 3 | +| 3 | Loss of power seconds | 4 | +| 4 | Errored seconds | 5 | +| 5 | Severely errored seconds | 6 | +| 6 | Line initializations | 7 | +| 7 | Failed line initializations | 8 | +| 8 | Short initializations | 9 | +| 9 | Failed short initializations | 10 | +| 10 | FEC seconds | 11 | +| 11 | Unavailable seconds | 12 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### **9.7.22 xDSL xTU-R performance monitoring history data** + +This ME collects PM data of the xTU-C to xTU-R path as seen from the xTU-R. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Loss of frame seconds:** (R) (mandatory) (2 bytes) + +**Loss of signal seconds:** (R) (mandatory) (2 bytes) + +**Loss of power seconds:** (R) (mandatory) (2 bytes) + +**Errored seconds:** This attribute counts 1 s intervals with one or more far end block error (FEBE) anomalies summed over all transmitted bearer channels, or one or more LOS-FE defects, or one or more RDI defects, or one or more LPR-FE defects. (R) (mandatory) (2 bytes) + +**Severely errored seconds:** This attribute counts severely errored seconds (SES-LFE). An SES is declared if, during a 1 s interval, 18 or more FEBE anomalies were reported across the totality of bearer channels, or there were one or more far-end LOS defects, one or more RDI defects or one or more LPR-FE defects. + +If the relevant Recommendation ([ITU-T G.992.3], [ITU-T G.992.5] or [ITU-T G.993.2]) supports a 1 s normalized CRC-8 anomaly counter increment, the 1 s SES counter follows this value instead of counting FEBE anomalies directly. + +If a CRC is applied for multiple bearer channels, then each related FEBE anomaly is counted only once for the whole set of related bearer channels. + +(R) (mandatory) (2 bytes) + +**FEC seconds:** This attribute counts seconds during which at least one uncorrectable FEC codeword was received. (R) (mandatory) (2 bytes) + +**Unavailable seconds:** This attribute counts 1 s intervals during which the far-end xDSL termination is unavailable. + +The far-end xDSL termination becomes unavailable at the onset of 10 contiguous SES-LFEs. The 10 SES-LFEs are included in unavailable time. Once unavailable, the far-end line becomes available at the onset of 10 contiguous seconds with no SES-LFEs. The 10 s with no SES-LFEs are excluded from unavailable time. Some attribute counts are inhibited during unavailability – see clause 7.2.7.13 of [ITU-T G.997.1]. + +(R) (mandatory) (2 bytes) + +**"leftr" defect seconds:** If retransmission is used, this parameter is a count of the seconds with a near-end "leftr" defect present – see clause 7.2.1.1.6 of [ITU-T G.997.1]. (R) (optional) (2 bytes) + +**Error-free bits counter:** If retransmission is used, this parameter is a count of the number of error-free bits passed over the $\beta 1$ reference point, divided by $2^{16}$ – see clause 7.2.1.1.7 of [ITU-T G.997.1]. (R) (optional) (4 bytes) + +**Minimum error-free throughput (MINEFTR):** If retransmission is used, this parameter is the minimum error-free throughput in bits per second – see clause 7.2.1.1.8 of [ITU-T G.997.1]. (R) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | Loss of frame seconds | 1 | +| 1 | Loss of signal seconds | 2 | +| 2 | Loss of power seconds | 3 | +| 3 | Errored seconds | 4 | +| 4 | Severely errored seconds | 5 | +| 5 | FEC seconds | 6 | +| 6 | Unavailable seconds | 7 | +| 7 | "leftfr" defect seconds | 8 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.7.23 xDSL xTU-C channel performance monitoring history data + +This ME collects PM data of an xTU-C to xTU-R channel as seen from the xTU-C. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an xDSL bearer channel. Several instances may therefore be associated with an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Corrected blocks:** This attribute counts blocks received with errors that were corrected on this channel. (R) (mandatory) (4 bytes) + +**Uncorrected blocks:** This attribute counts blocks received with uncorrectable errors on this channel. (R) (mandatory) (4 bytes) + +**Transmitted blocks:** This attribute counts encoded blocks transmitted on this channel. (R) (mandatory) (4 bytes) + +**Received blocks:** This attribute counts encoded blocks received on this channel. (R) (mandatory) (4 bytes) + +**Code violations:** This attribute counts CRC-8 anomalies in the bearer channel. (R) (mandatory) (2 bytes) + +**Forward error corrections:** This attribute counts FEC anomalies in the bearer channel. (R) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|---------------------------|--------------------------------------| +| 0 | Corrected blocks | 1 | +| 1 | Uncorrected blocks | 2 | +| 2 | Code violations | 3 | +| 3 | Forward error corrections | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.7.24 xDSL xTU-R channel performance monitoring history data** + +This ME collects PM data of the xTU-C to xTU-R channel as seen from the xTU-R. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an xDSL bearer channel. Several instances may therefore be associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Corrected blocks:** This attribute counts blocks received with errors that were corrected on this channel. (R) (mandatory) (4 bytes) + +**Uncorrected blocks:** This attribute counts blocks received with uncorrectable errors on this channel. (R) (mandatory) (4 bytes) + +**Transmitted blocks:** This attribute counts encoded blocks transmitted on this channel. (R) (mandatory) (4 bytes) + +**Received blocks:** This attribute counts encoded blocks received on this channel. (R) (mandatory) (4 bytes) + +**Code violations:** This attribute counts FEBE anomalies reported in the downstream bearer channel. If the CRC is applied over multiple bearer channels, then each related FEBE anomaly increments each of the counters related to the individual bearer channels. (R) (mandatory) (2 bytes) + +**Forward error corrections:** This attribute counts FFEC anomalies reported in the downstream bearer channel. If FEC is applied over multiple bearer channels, each related FFEC anomaly increments each of the counters related to the individual bearer channels. (R) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|---------------------------|--------------------------------------| +| 0 | Corrected blocks | 1 | +| 1 | Uncorrected blocks | 2 | +| 2 | Code violations | 3 | +| 3 | Forward error corrections | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.7.25 TC adaptor performance monitoring history data xDSL** + +This ME collects PM data of an xTU-C to xTU-R ATM data path. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data1/2 ID:** This attribute points to an instance of the threshold data1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Near-end HEC violation count:** This attribute counts near-end HEC anomalies in the ATM data path. (R) (mandatory) (2 bytes) + +**Near-end delineated total cell count (CD-P):** This attribute counts the total number of cells passed through the cell delineation and HEC function process operating on the ATM data path while in the SYNC state. (R) (mandatory) (4 bytes) + +- Near-end user total cell count(CU-P):** This attribute counts the total number of cells in the ATM data path delivered at the V-C interface. (R) (mandatory) (4 bytes) +- Near-end idle cell bit error count:** This attribute counts cells with bit errors in the ATM data path idle payload received at the near end. (R) (mandatory) (2 bytes) +- Far-end HEC violation count:** This attribute counts far-end HEC anomalies in the ATM data path. (R) (mandatory) (2 bytes) +- Far-end delineated total cell count (CD-PFE):** This attribute counts the total number of cells passed through the cell delineation process and HEC function operating on the ATM data path while in the SYNC state. (R) (mandatory) (4 bytes) +- Far-end user total cell count (CU-PFE):** This attribute counts the total number of cells in the ATM data path delivered at the T-R interface. (R) (mandatory) (4 bytes) +- Far-end idle cell bit error count:** This attribute counts cells with bit errors in the ATM data path idle payload received at the far end. (R) (mandatory) (2 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|----------------------------------------------|--------------------------------------| +| 0 | Near-end HEC violation | 1 | +| 1 | Near-end idle cell bit error count | 2 | +| 2 | Far-end HEC violation count | 3 | +| 3 | Far-end idle cell bit error count | 4 | +| 4 | Near-end delineated total cell count (CD-P) | 5 | +| 5 | Near-end user total cell count (CU-P) | 6 | +| 6 | Far-end delineated total cell count (CD-PFE) | 7 | +| 7 | Far-end user total cell count (CU-PFE) | 8 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.7.26 VDSL2 line configuration extensions 2** + +This ME extends the xDSL line configuration MEs. The ME name was chosen because its attributes were initially unique to ITU-T G.993.2 VDSL2. Due to continuing standards development, two of the attributes (FEXT and NEXT TXREFVNs) are also used in [ITU-T G.992.3] and [ITU-T G.992.5]. This ME therefore pertains to the latter Recommendations as well as to [ITU-T G.993.2]. + +The attributes of this ME are further defined in [ITU-T G.997.1]. + +An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PTP xDSL UNI part 1. + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID. (The client PPTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration parts.) + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PPTP xDSL must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**SOS time downstream:** The SOS-TIME-ds attribute is used in the specification of receiver initiated SOS (see clause 13.4.3 of [ITU-T G.993.2]). If the attribute value is not zero, the standard SOS triggering criteria are enabled, and the value specifies the duration of the window used in the standard SOS triggering criteria in the downstream direction. The special value zero indicates that the standard SOS triggering criteria are disabled, i.e., vendor-discretionary values may be used instead of the values configured in the MIB for the following parameters: SOS-NTONES-ds, SOS-CRC-ds, SOS-TIME-ds. The valid range of non-zero values is from 1..255, specifying 64 ms to 16320 ms in steps of 64 ms. (R, W, set-by-create) (optional) (1 byte) + +**SOS time upstream:** The SOS-TIME-us attribute is used in the specification of receiver initiated SOS (see clause 13.4.3 of [ITU-T G.993.2]). If the attribute value is not zero, the standard SOS triggering criteria are enabled, and the value specifies the duration of the window used in the standard SOS triggering criteria in the upstream direction. The special value zero indicates that the standard SOS triggering criteria are disabled, i.e., vendor-discretionary values may be used instead of the values configured in the MIB for the following parameters: SOS-NTONES-us, SOS-CRC-us, SOS-TIME-us. The valid range of non-zero values is from 1..255, specifying 64 ms to 16320 ms in steps of 64 ms. (R, W, set-by-create) (optional) (1 byte) + +**SOS degraded tones threshold downstream:** The SOS-NTONES-ds attribute is the minimum percentage of tones in the downstream medley set that must be degraded in order to arm the first sub-condition of the standard SOS triggering criteria in the downstream direction. The valid range of values is from 1 to 100% in steps of 1. Use of the special value 0 is described in clause 13.4.3.2 of [ITU-T G.993.2]. (R, W, set-by-create) (optional) (1 byte) + +**SOS degraded tones threshold upstream:** The SOS-NTONES-us attribute is the minimum percentage of tones in the upstream medley set that must be degraded in order to arm the first sub-condition of the standard SOS triggering criteria in the upstream direction. The valid range of values is from 1 to 100% in steps of 1. Use of the special value 0 is described in clause 13.4.3.2 of [ITU-T G.993.2]. (R, W, set-by-create) (optional) (1 byte) + +**SOS CRC threshold downstream:** The SOS-CRC-ds attribute is the minimum number of normalized CRC anomalies received in SOS-TIME-ds seconds in order to arm the second sub-condition of the standard SOS triggering criteria (see clause 13.4.3.2 of [ITU-T G.993.2]) in the downstream direction. The valid range of SOS-CRC values is 0.02 to $(2^{16}-1)*0.02$ , in steps of 0.02. The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (2 bytes) + +- SOS CRC threshold upstream:** The SOS-CRC-us attribute is the minimum number of normalized CRC anomalies received in SOS-TIME-us seconds in order to arm the second sub-condition of the standard SOS triggering criteria (see clause 13.4.3.2 of [ITU-T G.993.2]) in the upstream direction. The valid range of SOS-CRC values is 0.02 to $(2^{16}-1)*0.02$ , in steps of 0.02. The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (2 bytes) +- MAX SOS downstream:** The MAX-SOS-ds attribute is used in deactivation. If the number of successful SOS procedures in the downstream direction performed within a 120 s interval exceeds MAX-SOS-ds, the modem goes to state L3. See clause 12.1.4 of [ITU-T G.993.2] for details. The valid range of values is 1 to 15, with the special value 0 as described in clause 12.1 of [ITU-T G.993.2]. (R, W, set-by-create) (optional) (1 byte) +- MAX SOS upstream:** The MAX-SOS-us attribute is used in deactivation. If the number of successful SOS procedures in the upstream direction performed within a 120 s interval exceeds MAX-SOS-us, the modem goes to state L3. See clause 12.1.4 of [ITU-T G.993.2] for details. The valid range of values is 1 to 15, with the special value 0 as described in clause 12.1 of [ITU-T G.993.2]. (R, W, set-by-create) (optional) (1 byte) +- SNR max offset downstream:** The SNRMOFFSET-ROC-ds attribute is the SNR margin offset for the ROC in the downstream direction. The attribute is used in the specification of the channel initialization policy (see clause 12.3.7.1 of [ITU-T G.993.2]). The valid range of SNR margin offset values is from 0..31 dB in 0.1 dB steps. (R, W, set-by-create) (optional) (2 bytes) +- SNR max offset upstream:** The SNRMOFFSET-ROC-us attribute is the SNR margin offset for the ROC in the upstream direction. The attribute is used in the specification of the channel initialization policy (see clause 12.3.7.1 of [ITU-T G.993.2]). The valid range of SNR margin offset values is from 0..31 dB in 0.1 dB steps. (R, W, set-by-create) (optional) (2 bytes) +- ROC minimum impulse noise protection downstream:** The INPMIN-ROC-ds attribute specifies the minimum INP to apply on the ROC in the downstream direction expressed in multiples of equivalent 4k DMT, xDSL (DMT) symbol length. The minimum INP is an integer ranging from 0 to 8. (R, W, set-by-create) (optional) (1 byte) +- ROC minimum impulse noise protection upstream:** The INPMIN-ROC-us attribute specifies the minimum impulse noise protection to apply on the ROC in the upstream direction expressed in multiples of equivalent 4k DMT symbol length. The minimum INP is an integer ranging from 0 to 8. (R, W, set-by-create) (optional) (1 byte) +- FEXT downstream transmitter referred virtual noise table:** The FEXT TXREFVNs attribute is the downstream transmitter referred virtual noise specified for FEXTR duration in Annex C of [ITU-T G.992.3] (ADSL2) and Annex C of [ITU-T G.992.5] (ADSL2plus). The syntax of this attribute is the same as that of the TXREFVNs table attribute of the VDSL2 line configuration extensions ME. (R, W) (mandatory for Annex C of [ITU-T G.992.3] and Annex C of [ITU-T G.992.5]) ( $3 * N$ bytes, where $N$ is the number of breakpoints) +- NEXT downstream transmitter referred virtual noise table:** The NEXT TXREFVNs attribute is the downstream transmitter referred virtual noise specified for NEXTR duration in Annex C of [ITU-T G.992.3] (ADSL2) and Annex C of [ITU-T G.992.5] (ADSL2plus). The syntax of this attribute is the same as that + +of the TXREFVNDs table attribute of the VDSL2 line configuration extensions ME. (R, W) (mandatory for Annex C of [ITU-T G.992.3] and Annex C of [ITU-T G.992.5]) (3 \* *N* bytes, where *N* is the number of breakpoints) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.7.27 xDSL impulse noise monitor performance monitoring history data** + +This ME collects PM data from the impulse noise monitor function at both near and far ends. Instances of this ME are created and deleted by the OLT. Note that, unlike most xDSL PM, [ITU-T G.997.1] only requires current and previous 15 min interval storage; a longer view of this PM is not expected at 15 min granularity. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME may be associated with an xDSL UNI. This ME is meaningful only for ITU-T G.993.2 VDSL2, [ITU-T G.992.3] and [ITU-T G.992.5]. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** No thresholds are defined for this ME. For uniformity with other PM, the attribute is retained and shown as mandatory, but it should be set to a null pointer. (R, W, set-by-create) (mandatory) (2 bytes) + +**INM INPEQ histogram table:** INMINPEQ1..17-L is a count of the near-end INMAINPEQi anomalies occurring on the line during the accumulation period. This parameter is subject to inhibiting – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (optional) (2 bytes \* 17 entries = 34 bytes) + +**INM total measurement:** INMME-L is a count of the near-end INMAME anomalies occurring on the line during the accumulation period. This parameter is subject to inhibiting – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (optional) (2 bytes) + +**INM IAT histogram:** INMIAT0..7-L is a count of the near-end INMAIATi anomalies occurring on the line during the accumulation period. This parameter is subject to inhibiting – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (optional) (2 bytes \* 8 entries = 16 bytes) + +**INM INPEQ histogram LFE table:** INMINPEQ1..17-LFE is a count of the far-end INMAINPEQi anomalies occurring on the line during the accumulation period. This parameter is subject to inhibiting – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (optional) (2 bytes \* 17 entries = 34 bytes) + +**INM total measurement LFE:** INMME-LFE is a count of the far-end INMME anomalies occurring on the line during the accumulation period. This parameter is subject to inhibiting – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (optional) (2 bytes) + +**INM IAT histogram LFE:** INMIAT0..7-LFE is a count of the far-end INMAIATi anomalies occurring on the line during the accumulation period. This parameter is subject to inhibiting – see clause 7.2.7.13 of [ITU-T G.997.1]. (R) (optional) (2 bytes \* 8 entries = 16 bytes) + +#### *Actions* + +Create, delete, get, get next, set + +Get current data (optional) + +#### *Notifications* + +None. + +### **9.7.28 xDSL line inventory and status data part 5** + +This ME extends the attributes defined in the xDSL line inventory and status data parts 1..4. This ME reports FEXT and NEXT attributes, and pertains to Annex C of [ITU-T G.992.3] (ADSL2) and Annex C of [ITU-T G.992.5] (ADSL2plus). + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**FEXT downstream SNR margin:** The FEXT SNRMds attribute is the downstream SNR margin measured during FEXTR duration at the ATU-R. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) + +**NEXT downstream SNR margin:** The NEXT SNRMds attribute is the downstream SNR margin measured during NEXTR duration at the ATU-R. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) + +**FEXT upstream SNR margin:** The FEXT SNRMus attribute is the upstream SNR margin (see clause 7.5.1.16 of [ITU-T G.997.1]) measured during FEXTC duration at the ATU-C. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) + +**NEXT upstream SNR margin:** The NEXT SNRMus attribute is the upstream SNR margin (see clause 7.5.1.16 of [ITU-T G.997.1]) measured during NEXTC duration at the ATU-C. The attribute value ranges from 0 (–64.0 dB) to 1270 (+63.0 dB). The special value 0xFFFF indicates that the attribute is out of range. (R) (mandatory) (2 bytes) + +**FEXT downstream maximum attainable data rate:** The FEXT ATTNDRds attribute is the maximum downstream net data rate calculated from FEXT downstream + +SNR( $f$ ) (see clause 7.5.1.28.3.1 of [ITU-T G.997.1]). The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**NEXT downstream maximum attainable data rate:** The NEXT ATTNDRds attribute is the maximum downstream net data rate calculated from NEXT downstream SNR( $f$ ) (see clause 7.5.1.28.3.2 of [ITU-T G.997.1]). The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**FEXT upstream maximum attainable data rate:** The FEXT ATTNDRus attribute is the maximum upstream net data rate calculated from FEXT upstream SNR( $f$ ) (see clause 7.5.1.28.6.1 of [ITU-T G.997.1]). The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**NEXT upstream maximum attainable data rate:** The NEXT ATTNDRus attribute is the maximum upstream net data rate calculated from NEXT upstream SNR( $f$ ) (see clause 7.5.1.28.6.2 of [ITU-T G.997.1]). The rate is coded in bits per second. (R) (mandatory) (4 bytes) + +**FEXT downstream actual power spectral density:** The FEXT ACTPSDds attribute is the average downstream transmit PSD over the used subcarriers (see clause 7.5.1.21.1 of [ITU-T G.997.1]) calculated from the REFPSDds and RMSGIids for FEXTR duration. The attribute value ranges from 0 (–90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**NEXT downstream actual power spectral density:** The NEXT ACTPSDds attribute is the average downstream transmit PSD over the used subcarriers (see clause 7.5.1.21.2 of [ITU-T G.997.1]) calculated from the REFPSDds and RMSGIids for NEXTR duration. The attribute value ranges from 0 (–90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**FEXT upstream actual power spectral density:** The FEXT ACTPSDus attribute is the average upstream transmit PSD over the used subcarriers (see clause 7.5.1.22.1 of [ITU-T G.997.1]) calculated from the REFPSDus and RMSGIus for FEXTC duration. The attribute value ranges from 0 (–90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**NEXT upstream actual power spectral density:** The NEXT ACTPSDus attribute is the average upstream transmit PSD over the used subcarriers (see clause 7.5.1.22.2 of [ITU-T G.997.1]) calculated from the REFPSDus and RMSGIus for NEXTC duration. The attribute value ranges from 0 (–90.0 dBm/Hz) to 900 (0.0 dBm/Hz). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**FEXT downstream actual aggregate transmit power:** The FEXT ACTATPds attribute is the total amount of transmit power (see clause 7.5.1.24.1 of [ITU-T G.997.1]) calculated from PSDds measured during FEXTR duration at the ATU-R. The attribute value ranges from 0 (–31.0 dBm) to 620 (+31.0 dBm). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**NEXT downstream actual aggregate transmit power:** The NEXT ACTATPds attribute is the total amount of transmit power (see clause 7.5.1.24.2 of [ITU-T G.997.1]) calculated from PSDds measured during NEXTR duration at the ATU-R. The attribute value ranges from 0 (–31.0 dBm) to 620 (+31.0 dBm). The special + +value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**FEXT upstream actual aggregate transmit power:** The FEXT ACTATPus attribute is the total transmit power (see clause 7.5.1.25.1 of [ITU-T G.997.1]) calculated from PSDus measured during FEXTC duration at the ATU-C. The attribute value ranges from 0 (–31.0 dBm) to 620 (+31.0 dBm). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +**NEXT upstream actual aggregate transmit power:** The NEXT ACTATPus attribute is the total transmit power (see clause 7.5.1.25.2 of [ITU-T G.997.1]) calculated from PSDus measured during NEXTC duration at the ATU-C. The attribute value ranges from 0 (–31.0 dBm) to 620 (+31.0 dBm). The special value 0xFFFF indicates that the parameter is out of range. (R) (mandatory) (2 bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.29 xDSL line inventory and status data part 6** + +This ME extends the attributes defined in the xDSL line inventory and status data parts 1..4. This ME reports FEXT and NEXT attributes, and pertains to Annex C of [ITU-T G.992.3] (ADSL2) and Annex C of [ITU-T G.992.5] (ADSL2plus). + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**FEXT downstream quiet line noise PSD measurement time:** The FEXT QLNMTds attribute is the number of symbols used to measure FEXT downstream QLN(*f*) (see clause 7.5.1.27.3.1 of [ITU-T G.997.1]). (R) (mandatory) (2 bytes) + +**NEXT downstream quiet line noise PSD measurement time:** The NEXT QLNMTds attribute is the number of symbols used to measure NEXT downstream QLN(*f*) (see clause 7.5.1.27.3.2 of [ITU-T G.997.1]). (R) (mandatory) (2 bytes) + +**FEXT downstream QLN(*f*) table:** The FEXT QLNpsds attribute is the downstream QLN(*f*) (see clause 7.5.1.27.3.1 of [ITU-T G.997.1]) measured during FEXTR duration at the ATU-R. The attribute syntax is the same as that of the downstream QLNpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) (*N* bytes, where *N* is the number of subcarrier groups) + +**NEXT downstream QLN(*f*) table:** The NEXT QLNpsds attribute is the downstream QLN(*f*) (see clause 7.5.1.27.3.2 of [ITU-T G.997.1]) measured during NEXTR duration at the ATU-R. The attribute syntax is the same as that of the downstream QLNpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) (*N* bytes, where *N* is the number of subcarrier groups) + +- FEXT upstream quiet line noise PSD measurement time:** The FEXT QLNMTus attribute is the number of symbols used to measure FEXT upstream $QLN(f)$ (see clause 7.5.1.27.6.1 of [ITU-T G.997.1]). (R) (mandatory) (2 bytes) +- NEXT upstream quiet line noise PSD measurement time:** The NEXT QLNMTus attribute is the number of symbols used to measure NEXT upstream $QLN(f)$ (see clause 7.5.1.27.6.2 of [ITU-T G.997.1]). (R) (mandatory) (2 bytes) +- FEXT upstream $QLN(f)$ table:** The FEXT QLNpsus attribute is the upstream $QLN(f)$ (see clause 7.5.1.27.6.1 of [ITU-T G.997.1]) measured during FEXTC duration at the ATU-C. The attribute syntax is the same as that of the downstream QLNpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarrier groups) +- NEXT upstream $QLN(f)$ table:** The NEXT QLNpsus attribute is the upstream $QLN(f)$ (see clause 7.5.1.27.6.2 of [ITU-T G.997.1]) measured during NEXTC duration at the ATU-C. The attribute syntax is the same as that of the downstream QLNpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarrier groups) +- FEXT downstream SNR measurement time:** The FEXT SNRMTds attribute is the number of symbols used to measure FEXT downstream $SNR(f)$ values (see clause 7.5.1.28.1.1 of [ITU-T G.997.1]). Its value corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) +- NEXT downstream SNR measurement time:** The NEXT SNRMTds attribute is the number of symbols used to measure NEXT downstream $SNR(f)$ values (see clause 7.5.1.28.1.2 of [ITU-T G.997.1]). Its value corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) +- FEXT downstream $SNR(f)$ table:** The FEXT SNRpsds attribute is the downstream $SNR(f)$ (see clause 7.5.1.28.3.1 of [ITU-T G.997.1]) measured during FEXTR duration at the ATU-R. The attribute is represented in the same way as the SNRpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarrier groups) +- NEXT downstream $SNR(f)$ table:** The NEXT SNRpsds attribute is the downstream $SNR(f)$ (see clause 7.5.1.28.3.2 of [ITU-T G.997.1]) measured during NEXTR duration at the ATU-R. The attribute is represented in the same way as the SNRpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarrier groups) +- FEXT upstream SNR measurement time:** The FEXT SNRMTus attribute is the number of symbols used to measure FEXT upstream $SNR(f)$ values (see clause 7.5.1.28.4.1 of [ITU-T G.997.1]). Its value corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) +- NEXT upstream SNR measurement time:** The NEXT SNRMTus attribute is the number of symbols used to measure NEXT upstream $SNR(f)$ values (see clause 7.5.1.28.4.2 of [ITU-T G.997.1]). Its value corresponds to the value specified in the corresponding Recommendation (e.g., the number of symbols in a 1 s interval for [ITU-T G.992.3]). (R) (mandatory) (2 bytes) +- FEXT upstream $SNR(f)$ table:** The FEXT SNRpsus attribute is the upstream $SNR(f)$ (see clause 7.5.1.28.6.1 of [ITU-T G.997.1]) measured during FEXTC duration at + +the ATU-C. The attribute is represented in the same way as the SNRpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarrier groups) + +**NEXT upstream SNR( $f$ ) table:** The NEXT SNRpsus attribute is the upstream SNR( $f$ ) (see clause 7.5.1.28.6.2 of [ITU-T G.997.1]) measured during NEXTC duration at the ATU-C. The attribute is represented in the same way as the SNRpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarrier groups) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.30 xDSL line inventory and status data part 7** + +This ME extends the attributes defined in the xDSL line inventory and status data parts 1..4. This ME reports FEXT and NEXT attributes, and pertains to Annex C of [ITU-T G.992.3] (ADSL2) and Annex C of [ITU-T G.992.5] (ADSL2plus). + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**FEXT downstream bits allocation table:** The FEXT BITSpsds attribute is the downstream bits allocation table per subcarrier (see clause 7.5.1.29.1.1 of [ITU-T G.997.1]) used during FEXTR duration. The syntax of this attribute is the same as that of the BITSpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarriers) + +**NEXT downstream bits allocation table:** The NEXT BITSpsds attribute is the downstream bits allocation table per subcarrier (see clause 7.5.1.29.1.2 of [ITU-T G.997.1]) used during NEXTR duration. The syntax of this attribute is the same as that of the BITSpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarriers) + +**FEXT upstream bits allocation table:** The FEXT BITSpsus attribute is the upstream bits allocation table per subcarrier (see clause 7.5.1.29.2.1 of [ITU-T G.997.1]) used during FEXTC duration. The syntax of this attribute is the same as that of the BITSpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarriers) + +**NEXT upstream bits allocation table:** The NEXT BITSpsus attribute is the upstream bits allocation table per subcarrier (see clause 7.5.1.29.2.2 of [ITU-T G.997.1]) used during NEXTC duration. The syntax of this attribute is the same as that of the BITSpsds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $N$ bytes, where $N$ is the number of subcarriers) + +- FEXT downstream gains allocation table:** The FEXT GAINSpds attribute is the downstream gains allocation table per subcarrier (see clause 7.5.1.29.3.1 of [ITU-T G.997.1]) used during FEXTR duration. The syntax of this attribute is the same as that of the GAINSpds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $2N$ bytes, where $N$ is the number of subcarriers) +- NEXT downstream gains allocation table:** The NEXT GAINSpds attribute is the downstream gains allocation table per subcarrier (see clause 7.5.1.29.3.2 of [ITU-T G.997.1]) used during NEXTR duration. The syntax of this attribute is the same as that of the GAINSpds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $2N$ bytes, where $N$ is the number of subcarriers) +- FEXT upstream gains allocation table:** The FEXT GAINSpus attribute is the upstream gains allocation table per subcarrier (see clause 7.5.1.29.4.1 of [ITU-T G.997.1]) used during FEXTC duration. The syntax of this attribute is the same as that of the GAINSpds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $2N$ bytes, where $N$ is the number of subcarriers) +- NEXT upstream gains allocation table:** The NEXT GAINSpus attribute is the upstream gains allocation table per subcarrier (see clause 7.5.1.29.4.2 of [ITU-T G.997.1]) used during NEXTC duration. The syntax of this attribute is the same as that of the GAINSpds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $2N$ bytes, where $N$ is the number of subcarriers) +- FEXT downstream transmit spectrum shaping table:** The FEXT TSSpds attribute is the downstream transmit spectrum shaping parameter set per subcarrier (see clause 7.5.1.29.5.1 of [ITU-T G.997.1]) used during FEXTR duration. The syntax of this attribute is the same as that of the TSSpds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $3N$ bytes, where $N$ is the number of breakpoints) +- NEXT downstream transmit spectrum shaping table:** The NEXT TSSpds attribute is the downstream transmit spectrum shaping parameter set per subcarrier (see clause 7.5.1.29.5.2 of [ITU-T G.997.1]) used during NEXTR duration. The syntax of this attribute is the same as that of the TSSpds table attribute of the xDSL line inventory and status data part 3 ME. (R) (mandatory) ( $3N$ bytes, where $N$ is the number of breakpoints) +- FEXT upstream transmit spectrum shaping table:** The FEXT TSSpus attribute is the upstream transmit spectrum shaping parameter set per subcarrier (see clause 7.5.1.29.6.1 of [ITU-T G.997.1]) used during FEXTC duration. The syntax of this attribute is the same as that of the TSSpus table attribute of the xDSL line inventory and status data part 4 ME. (R) (mandatory) ( $3N$ bytes, where $N$ is the number of breakpoints) + +**NEXT upstream transmit spectrum shaping table:** The NEXT TSSpsus attribute is the upstream transmit spectrum shaping parameter set per subcarrier (see clause 7.5.1.29.6.2 of [ITU-T G.997.1]) used during NEXTC duration. The syntax of this attribute is the same as that of the TSSpsus table attribute of the xDSL line inventory and status data part 4 ME. (R) (mandatory) (3*N* bytes, where *N* is the number of breakpoints) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.31 xDSL xTU-C performance monitoring history data part 2** + +This ME collects PM data on the xTU-C to xTU-R path as seen from the xTU-C. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**"leftr" defect seconds:** If retransmission is used, this attribute is a count of the seconds with a near-end "leftr" defect present – see clause 7.2.1.1.6 of [ITU-T G.997.1]. (R) (mandatory) (2 bytes) + +**Error-free bits counter:** If retransmission is used, this attribute is a count of the number of error-free bits passed over the $\beta_1$ reference point, divided by $2^{16}$ – see clause 7.2.1.1.7 of [ITU-T G.997.1]. (R) (mandatory) (4 bytes) + +**Minimum error-free throughput (MINEFTR):** If retransmission is used, this attribute is the minimum error-free throughput in bits per second – see clause 7.2.1.1.8 of [ITU-T G.997.1]. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------|--------------------------|-----------------------------------------| +| 0 | "leftfr" defect seconds | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.7.32 PTM performance monitoring history data xDSL + +This ME collects PM data of an xTU-C to xTU-R PTM data path. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Near-end CRC-P counter:** This attribute is a count of the number of occurrences of a CRC-n anomaly in the PTM data path at the near-end – see clause 7.2.5.1.1 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (2 bytes) + +**Near-end CRCP-P counter:** This attribute is a count of the number of occurrences of a CRC-np anomaly in the PTM data path at the near-end – see clause 7.2.5.1.1 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (2 bytes) + +**Near-end CV-P counter:** This attribute is a count of the number of occurrences of a CV-n anomaly in the PTM data path at the near-end – see clause 7.2.5.1.2 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. ® (mandatory) (4 bytes) + +**Near-end CVP-P counter:** This attribute is a count of the number of occurrences of a CV-np anomaly in the PTM data path at the near-end – see clause 7.2.5.1.2 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (4 bytes) + +**Far-end CRC-PFE counter:** This attribute is a count of the number of occurrences of a CRC-n anomaly in the PTM data path at the far-end – see clause 7.2.5.2.1 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (2 bytes) + +**Far-end CRCP-PFE counter:** This attribute is a count of the number of occurrences of a CRC-np anomaly in the PTM data path at the far-end – see clause 7.2.5.2.1 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (2 bytes) + +**Far-end CV-PFE counter:** This attribute is a count of the number of occurrences of a CV-n anomaly in the PTM data path at the far-end – see clause 7.2.5.2.2 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (4 bytes) + +**Far-end CVP-PFE counter:** This attribute is a count of the number of occurrences of a CV-np anomaly in the PTM data path at the far-end – see clause 7.2.5.2.2 of [ITU-T G.997.1] and clause N.4 of [ITU-T G.992.3]. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | Near-end CRC-P counter | 1 | +| 1 | Near-end CRCP-P counter | 2 | +| 2 | Near-end CV-P counter | 3 | +| 3 | Near-end CVP-P counter | 4 | +| 4 | Far-end CRC-PFE counter | 5 | +| 5 | Far-end CRCP-PFE counter | 6 | +| 6 | Far-end CV-PFE counter | 7 | +| 7 | Far-end CVP-PFE counter | 8 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.7.33 VDSL2 line configuration extensions 3** + +This ME extends the xDSL line configuration MEs. + +An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of an xDSL UNI. + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (the client PTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration parts). + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) +- RIPOLICYds:** This attribute indicates which policy shall be applied to determine the triggers for re-initialization in the downstream direction. A valid range of values is given in clause 7.3.1.1.12.1 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- RIPOLICYus:** This attribute indicates which policy shall be applied to determine the triggers for re-initialization in the upstream direction. A valid range of values is given in clause 7.3.1.1.12.2 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- REINIT\_TIME\_THRESHOLDds:** This attribute indicates defines the downstream threshold for re-initialization based on SES, to be used by the VTU receiver when re-initialization policy 1 is used in downstream. A valid range of values is given in clause 7.3.1.1.13.1 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- REINIT\_TIME\_THRESHOLDus:** This attribute indicates defines the upstream threshold for re-initialization based on SES, to be used by the VTU receiver when re-initialization policy 1 is used in upstream. A valid range of values is given in clause 7.3.1.1.13.2 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- RXREFVNSFus:** If SNRM\_MODE = 4, this attribute defines the upstream receiver-referred virtual noise scaling factor. The attribute value ranges from 0 (–64.0 dBm) to 255 (+63.5 dBm) – see clause 7.3.1.7.5 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- TXREFVNSFds:** If SNRM\_MODE = 4, this attribute defines the downstream transmitter referred virtual noise scaling factor. The attribute value ranges from 0 (–64.0 dBm) to 255 (+63.5 dBm) – see clause 7.3.1.7.6 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- RTX\_MODEds:** This attribute controls the mode of operation of [ITU-T G.998.4] retransmission in the downstream direction. A valid range of values is given in clause 7.3.1.11 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- RTX\_MODEus:** This attribute controls the mode of operation of [ITU-T G.998.4] retransmission in the upstream direction. A valid range of values is given in clause 7.3.1.11 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- LEFTR\_THRESH:** If retransmission is used in a given transmit direction, LEFTR\_THRESH specifies the threshold for declaring a near-end "leftr" defect. LEFTR\_THRESH is equal to the integer value of this attribute multiplied by 0.01. Valid values and usage are given in clause 7.3.1.12 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- MAXDELAYOCTET-split parameter (MDOSPLIT):** This attribute defines the percentage of the MAXDELAYOCTET\_ext if operating in [ITU-T G.998.4] or MAXDELAYOCTET in other cases allocated to the downstream direction. MDOSPLIT is equal to the integer value of this attribute multiplied by 1%. Valid values and usage are given in clause 7.3.1.14 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) + +**ATTNDR Method (ATTNDR\_METHOD)**: This attribute specifies the method to be used for the calculation of the ATTNDR in the downstream and upstream direction. Valid values are given in clause 7.3.1.15.1 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) + +**ATTNDR MAXDELAYOCTET-split parameter (ATTNDR\_MDOSPLIT)**: This attribute defines the percentage of the MAXDELAYOCTET\_ext if operating in [ITU-T G.998.4] or MAXDELAYOCTET in other cases allocated to the downstream direction to be used in the improved method for calculation of the ATTNDR. The valid values are identical to the values of the line configuration parameter MDOSPLIT. See clause 7.3.1.15.2 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) + +#### ***Actions*** + +Create, delete, get, set + +#### ***Notifications*** + +None. + +### **9.7.34 Vectoring line configuration extensions** + +This ME extends the xDSL line configuration MEs with attributes that are specific to vectoring. An instance of this ME is created and deleted by the OLT. + +#### ***Relationships*** + +An instance of this ME may be associated with zero or more instances of an xDSL UNI. + +The overall xDSL line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (the client PPTP xDSL UNI part 1 has a single pointer, which refers to the entire set of line configuration parts). + +#### ***Attributes*** + +**Managed entity ID**: This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 and vectoring line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**Vectoring frequency-band control upstream (VECTOR\_BAND\_CONTROLus) table**: This configuration parameter is an array of pairs of sub-carrier indices [ $a(i)$ , $b(i)$ ]. Up to eight frequency bands may be configured. The same value of this parameter shall be set for all lines of the same vector group. See clause 7.3.1.13.1 of [ITU-T G.997.1]. + +This attribute is a table where each entry comprises: + +- band number field, $i$ (1 byte, range 1-8); +- band start subcarrier index, $a(i)$ (2 bytes); +- band stop subcarrier index, $b(i)$ (2 bytes). + +The band number field is the table index. By default, the table is empty. Setting a table entry with non-zero subcarrier indices implies insertion into the table. Setting an entry's subcarrier indices to zero implies deletion from the table, if present. + +The maximum number of bands is eight, so the maximum size of the table is 40 bytes. (R, W) (mandatory) ( $N \times 5$ bytes) + +- Vectoring frequency-band control downstream (VECTOR\_BAND\_CONTROLDs) table:** This configuration parameter is an array of pairs of sub-carrier indices $[a(i), b(i)]$ . Up to eight frequency bands may be configured. The same value of this parameter shall be set for all lines of the same vector group. See clause 7.3.1.13.2 of [ITU-T G.997.1]. The format of this attribute is the same as VECTOR\_BAND\_CONTROLUs. The maximum number of bands is eight, so the maximum size of the table is 40 bytes. (R, W) (mandatory) ( $N \times 5$ bytes) +- FEXT cancellation line priorities upstream (FEXT\_CANCEL\_PRIORITYUs):** This attribute specifies line priority for the line in the vectored group in the upstream direction. Allowed values are 0 (LOW) and 1 (HIGH). See clause 7.3.1.13.3 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- FEXT cancellation line priorities downstream (FEXT\_CANCEL\_PRIORITYDs):** This attribute specifies line priority for the line in the vectored group in the downstream direction. Allowed values are 0 (LOW) and 1 (HIGH). See clause 7.3.1.13.4 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- FEXT cancellation enabling/disabling upstream (FEXT\_CANCEL\_ENABLEUs):** A value of 1 enables and a value of 0 disables FEXT cancellation in the upstream direction from all the other vectored lines into the line in the vectored group. See clause 7.3.1.13.5 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- FEXT cancellation enabling/disabling downstream (FEXT\_CANCEL\_ENABLEDs):** A value of 1 enables and a value of 0 disables FEXT cancellation in the downstream direction from all the other vectored lines into the line in the vectored group. See clause 7.3.1.13.6 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- Downstream requested XLIN subcarrier group size (XLINGREQDs):** This attribute is the requested value of XLINGDs. Valid values are given in clause 7.3.1.13.7 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- Upstream requested XLIN subcarrier group size (XLINGREQUs):** This attribute is the requested value of XLINGUs. Valid values are given in clause 7.3.1.13.8 of [ITU-T G.997.1]. (R, W) (mandatory) (1 byte) +- Vectoring mode enable (VECTORMODE\_ENABLE):** This attribute defines the vectoring initialization type to be allowed by the VTU-O on the line. It is coded in a bit-map representation as defined in clause 7.3.1.13.9 of [ITU-T G.997.1]. (R, W) (optional) (1 byte) +- VCE ID (VCE\_ID):** For the line in a vectored group, the VCE ID uniquely identifies the VCE that manages and controls the vectored group to which the line belongs. The valid range of values is given in clause 7.4.13.1 of [ITU-T G.997.1]. (R) (mandatory) (1 byte) +- VCE port index (VCE\_port\_index):** For the line in a vectored group, the VCE port index is the physical index that uniquely identifies the VCE port to which the line is connected. The valid range of values is given in clause 7.4.13.2 of [ITU-T G.997.1]. (R) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.7.35 xDSL channel configuration profile part 2** + +This ME contains the channel configuration profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +NOTE – If [ITU-T G.997.1] compatibility is required, bit rates should only be set to integer multiples of 1000 bits/s. The ONU may reject attempts to set other values for bit rate attributes. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the xDSL channel configuration profile. (R, set-by-create) (mandatory) (2 bytes) + +**Minimum expected throughput for retransmission (MINETR\_RTX):** If retransmission is used in a given transmit direction, this attribute specifies the minimum expected throughput for the bearer channel, in bits per second. See clause 7.3.2.1.8 of [ITU-T G.997.1]. (R, W) (mandatory) (4 bytes) + +**Maximum expected throughput for retransmission (MAXETR\_RTX):** If retransmission is used in a given transmit direction, this parameter specifies the maximum expected throughput for the bearer channel, in bits per second. See clause 7.3.2.1.9 of [ITU-T G.997.1]. (R, W) (mandatory) (4 bytes) + +**Maximum net data rate for retransmission (MAXNDR\_RTX):** If retransmission is used in a given transmit direction, this parameter specifies the maximum net data rate for the bearer channel, in bits per second. See clause 7.3.2.1.10 of [ITU-T G.997.1]. (R, W) (mandatory) (4 bytes) + +**Maximum delay for retransmission (DELAYMAX\_RTX):** If retransmission is used in a given transmit direction, this parameter specifies the maximum for the instantaneous delay due to the effect of retransmission only. This delay is defined as the integer value of this attribute multiplied by 1 ms. The valid delay values are given in clause 7.3.2.11 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) + +**Minimum delay for retransmission (DELAYMIN\_RTX):** If retransmission is used in a given transmit direction, this parameter specifies the minimum for the instantaneous delay due to the effect of retransmission only. This delay is defined as the integer value of this attribute multiplied by 1 ms. The valid delay values are given in clause 7.3.2.12 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) + +**Minimum impulse noise protection against single high impulse noise event (SHINE) for retransmission (INPMIN\_SHINE\_RTX):** If retransmission is used in a given transmit direction, this parameter specifies the minimum INP against a SHINE for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 4.3125 kHz. The valid range of values is given in clause 7.3.2.13 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) + +- Minimum impulse noise protection against SHINE for retransmission for systems using 8.625 kHz subcarrier spacing (INPMIN8\_SHINE\_RTX)**: If retransmission is used in a given transmit direction, this parameter specifies the minimum INP against SHINE for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 8.625 kHz. The valid range of values is given in clause 7.3.2.14 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) +- SHINERATIO\_RTX**: If retransmission is used in a given transmit direction, this parameter specifies the SHINE ratio. This ratio is defined as the integer value of this attribute multiplied by 0.001. The valid range of values is given in clause 7.3.2.15 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) +- Minimum impulse noise protection against REIN for retransmission (INPMIN\_REIN\_RTX)**: If retransmission is used in a given transmit direction, this parameter specifies the minimum INP against REIN for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 4.3125 kHz. The valid range of values is given in clause 7.3.2.16 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) +- Minimum impulse noise protection against REIN for retransmission for systems using 8.625 kHz subcarrier spacing (INPMIN8\_REIN\_RTX)**: If retransmission is used in a given transmit direction, this parameter specifies the minimum INP against REIN for the bearer channel if it is transported over DMT symbols with a subcarrier spacing of 8.625 kHz. The valid range of values is given in clause 7.3.2.17 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) +- REIN inter-arrival time for retransmission (IAT\_REIN\_RTX)**: If retransmission is used in a given transmit direction, this parameter specifies the IAT that shall be assumed for REIN protection. The valid range of values is given in clause 7.3.2.18 of [ITU-T G.997.1]. (R, W) (mandatory) (1 bytes) +- Target net data rate (TARGET\_NDR)**: If retransmission is not used in a given transmit direction, this parameter specifies the target net data of the bearer channel, in bits per second. See clause 7.3.2.19.1 of [ITU-T G.997.1]. (R, W) (mandatory) (4 bytes) +- Target expected throughput for retransmission (TARGET\_ETR)**: If retransmission is used in a given transmit direction, this parameter specifies the target expected throughput for the bearer channel, in bits per second. See clause 7.3.2.19.2 of [ITU-T G.997.1]. (R, W) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.7.36 xTU data gathering configuration** + +This ME defines configurations specific to data gathering. + +An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R, set-by-create) (mandatory) (2 bytes) + +**Logging depth event percentage per event – VTU-O (LOGGING\_DEPTH\_EVENT\_PERCENTAGE\_Oi) table:** This parameter is the percentage of the data gathering event buffer assigned to event type *i* at the VTU-O. See clause 7.3.6.1 of [ITU-T G.997.1]. Each element in the table consists of 2 bytes, where the first byte is event type *i*, and the second byte is the percentage of event type *i* defined as the integer value multiplied by 1%. (R, W) (optional) ( $2 \times N$ bytes for *N* event types) + +**Logging depth event percentage per event – VTU-R (LOGGING\_DEPTH\_EVENT\_PERCENTAGE\_Ri) table:** This parameter is the percentage of the data gathering event buffer assigned to event type *i* at the VTU-R. See clause 7.3.6.2 of [ITU-T G.997.1]. Each element in the table consists of 2 bytes, where the first byte is event type *i*, and the second byte is the percentage of event type *i* defined as the integer value multiplied by 1%. (R, W) (optional) ( $2 \times N$ bytes for *N* event types) + +**Logging depth for VTU-O reporting – VTU-R (LOGGING\_DEPTH\_REPORTING\_O):** This parameter is the logging depth that is requested for reporting the VTU-O event trace buffer in the CO-MIB, in number of 6 byte data gathering records. See clause 7.3.6.3 of [ITU-T G.997.1]. (R, W) (optional) (2 bytes) + +**Logging depth for VTU-R reporting – VTU-R (LOGGING\_DEPTH\_REPORTING\_R):** This parameter is the logging depth that is requested for reporting the VTU-R event trace buffer over the embedded operations channel (eoc), in number of 6 byte data gathering records. See clause 7.3.6.4 of [ITU-T G.997.1]. (R, W) (optional) (2 bytes) + +**Logging data report newer events first – VTU-R (LOGGING\_REPORT\_NEWER\_FIRST):** This parameter determines whether the VTU-R to reports newer events first or older events first. See clause 7.3.6.4 of [ITU-T G.997.1]. False is mapped to 0, true is mapped to 1. (R, W) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.7.37 xDSL line inventory and status data part 8** + +This ME extends the attributes defined in the xDSL line inventory and status data parts 1..4. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**Retransmission used downstream (RTX\_USEDds):** This parameter specifies whether [ITU-T G.998.4] retransmission is used (i.e., active in showtime) in the downstream transmit direction. The valid range of values is given in clause 7.5.1.38 of [ITU-T G.997.1]. (R) (mandatory) (1 byte) + +**Retransmission used upstream (RTX\_USEDus):** This parameter specifies whether [ITU-T G.998.4] retransmission is used (i.e., active in showtime) in the upstream transmit direction. The valid range of values is given in clause 7.5.1.38 of [ITU-T G.997.1]. (R) (mandatory) (1 byte) + +**Date/time-stamping of near-end test parameters (STAMP-TEST-NE):** This parameter indicates the date/time when the near-end test parameters that can change during showtime were last updated. See clause 7.5.1.36.3 of [ITU-T G.997.1]. The format of this parameter is as follows. + +| | | +|--------|----------------| +| Year | 2 bytes | +| Month | 1 byte (1..12) | +| Day | 1 byte (1..31) | +| Hour | 1 byte (0..23) | +| Minute | 1 byte (0..59) | +| Second | 1 byte (0..59) | + +(R) (optional) (7 bytes) + +**Date/time-stamping of far-end test parameters (STAMP-TEST-FE):** This parameter indicates the date/time when the far-end test parameters that can change during showtime were last updated. See clause 7.5.1.36.4 of [ITU-T G.997.1]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) + +**Date/time-stamping of last successful downstream OLR operation (STAMP-OLR-ds):** This parameter indicates the date/time of the last successful OLR execution in the downstream direction that has modified the bits or gains. See clause 7.5.1.37.1 of [ITU-T G.997.1]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) + +**Date/time-stamping of last successful upstream OLR operation (STAMP-OLR-us):** This parameter indicates the date/time of the last successful OLR execution in the upstream direction that has modified the bits or gains. See clause 7.5.1.37.2 of [ITU-T G.997.1]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### 9.7.38 VDSL2 line inventory and status data part 4 + +This ME extends the other xDSL line inventory and status data MEs with attributes specific to VDSL2. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. It is required only if VDSL2 is supported by the PPTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**VTU-O estimated upstream power back-off electrical length per band (UPBOKLE-pb):** This parameter is a vector of UPBO electrical length per-band estimates for each supported upstream band except US0, calculated by the VTU-O, based on separate measurements in the supported upstream bands excluding US0. This parameter is required for the alternative electrical length estimation method (ELE-M1). Each per-band estimate is represented by 2 bytes, where the estimate is defined as the integer value multiplied by 0.1 dB. The valid range of values is given in clause 7.5.1.23.3 of [ITU-T G.997.1] (R) (optional) (4 bands $\times$ 2 bytes) + +**VTU-R estimated upstream power back-off electrical length per band (UPBOKLE-R-pb):** This parameter is a vector of UPBO electrical length per-band estimates for each supported downstream band, calculated by the VTU-R, based on separate measurements in the supported downstream bands. This parameter is required for the alternative electrical length estimation method (ELE-M1). Each per-band estimate is represented by 2 bytes, where the estimate is defined as the integer value multiplied by 0.1 dB. The valid range of values is given in clause 7.5.1.23.4 of [ITU-T G.997.1] (R) (optional) (3 bands $\times$ 2 bytes) + +**UPBO downstream receiver signal level threshold (RXTHRSHds):** This parameter reports the downstream received signal level threshold value used in the alternative electrical length estimation method (ELE-M1). Valid values range from 0 (–64 dB) to 64 (0 dB). See clause 7.5.1.23.5 of [ITU-T G.997.1] (R) (optional) (1 byte) + +**UPBO upstream receiver signal level threshold (RXTHRSHus):** This parameter reports the upstream received signal level threshold value used in the alternative electrical length estimation method. Valid values range from 0 (–64 dB) to 64 (0 dB). See clause 7.5.1.23.6 of [ITU-T G.997.1] (R) (optional) (1 byte) + +**Actual alternative electrical length estimation mode (ACT-AELE-MODE):** This parameter reports the actual AELE-MODE. Valid values are given in clause 7.5.1.23.7 of [ITU-T G.997.1] (R) (optional) (1 byte) + +**Actual downstream RIPOLICY (ACTRIPOLICYds):** This parameter indicates the actual re-initialization policy in use in the downstream direction. Valid values are given in clause 7.5.1.40.1 of [ITU-T G.997.1] (R) (optional) (1 byte) + +**Actual upstream RIPOLICY (ACTRIPOLICYus):** This parameter indicates the actual re-initialization policy in use in the upstream direction. Valid values are given in clause 7.5.1.40.2 of [ITU-T G.997.1] (R) (optional) (1 byte) + +- ATTNDR actual method (ATTNDR\_ACTMETHOD):** This parameter indicates the actual ATTNDR Method used for calculation of the ATTNDR in the downstream and upstream direction. Valid values are given in clause 7.5.1.41.1 of [ITU-T G.997.1] (R) (optional) (1 byte) +- ATTNDR downstream actual impulse noise protection (ATTNDR\_ACTINPds):** If retransmission is not used in the downstream direction, this parameter indicates the actual INP used in the improved calculation of the ATTNDR in the downstream direction. If retransmission is used in the downstream direction, this parameter indicates the actual INP against SHINE used in the improved calculation of the ATTNDR in the downstream direction. The format and usage is identical to that of the ACTINP attribute defined in the xDSL channel downstream status data ME. See clause 7.5.1.41.2 of [ITU-T G.997.1] (R) (optional) (1 byte) +- ATTNDR upstream actual impulse noise protection (ATTNDR\_ACTINPus):** If retransmission is not used in the upstream direction, this parameter indicates the actual INP used in the improved calculation of the ATTNDR in the upstream direction. If retransmission is used in the upstream direction, this parameter indicates the actual INP against SHINE used in the improved calculation of the ATTNDR in the upstream direction. The format and usage is identical to that of the ACTINP attribute defined in the xDSL channel downstream status data ME. See clause 7.5.1.41.3 of [ITU-T G.997.1] (R) (optional) (1 byte) +- ATTNDR downstream actual impulse noise protection against REIN (ATTNDR\_ACTINP\_REINds):** If retransmission is used in the downstream direction, this parameter reports the actual INP against REIN used in the improved calculation of the ATTNDR in the downstream direction. The format and usage is identical to that of the ACTINP\_REIN attribute defined in the xDSL channel downstream status data ME. See clause 7.5.1.41.4 of [ITU-T G.997.1] (R) (optional) (1 byte) +- ATTNDR upstream actual impulse noise protection against REIN (ATTNDR\_ACTINP\_REINus):** If retransmission is used in the upstream direction, this parameter reports the actual INP against REIN used in the improved calculation of the ATTNDR in the upstream direction. The format and usage is identical to that of the ACTINP\_REIN attribute defined in the xDSL channel downstream status data ME. See clause 7.5.1.41.5 of [ITU-T G.997.1] (R) (optional) (1 byte) +- ATTNDR downstream actual delay (ATTNDR\_ACTDELAYds):** This parameter indicates the actual delay used in the improved calculation of the ATTNDR in the downstream direction. The delay of this attribute is equal to the integer value multiplied by 0.1 ms. Valid values are given in clause 7.5.1.41.6 of [ITU-T G.997.1] (R) (optional) (1 byte) +- ATTNDR upstream actual delay (ATTNDR\_ACTDELAYus):** This parameter indicates the actual delay used in the improved calculation of the ATTNDR in the upstream direction. The delay of this attribute is equal to the integer value multiplied by 0.1 ms. Valid values are given in clause 7.5.1.41.7 of [ITU-T G.997.1] (R) (optional) (1 byte) +- Near-end aggregate achievable net data rate (AGGACHNDR\_NE):** This parameter reports the aggregate achievable net data rate of the VTU-O, in bits per second. See clause 7.5.1.42.1 of [ITU-T G.997.1] (R) (optional) (4 bytes) + +**Far-end aggregate achievable net data rate (AGGACHNDR\_FE)**: This parameter reports the aggregate achievable net data rate of the VTU-R, in bits per second. See clause 7.5.1.42.2 of [ITU-T G.997.1] (R) (optional) (4 bytes) + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.7.39 Vectoring line inventory and status data** + +This ME contains line inventory and status attributes specific to vectoring. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI. It is meaningful if the PTPP supports [ITU-T G.993.5]. The ONU automatically creates or deletes an instance of this ME upon creation and deletion of a PTPP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID**: This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PTPP xDSL UNI part 1 ME. (R) (mandatory) (2 bytes) + +**Downstream XLIN scale (XLINSCds)**: This parameter is the scale factor to be applied to the downstream Xlinsds values. Valid values are given in clause 7.5.1.39.1 of [ITU-T G.997.1] (R) (mandatory) (2 bytes) + +**Downstream XLIN subcarrier group size (XLINGds)**: This parameter is the number of subcarriers per group used to report Xlinsds. Valid values are given in clause 7.5.1.39.2 of [ITU-T G.997.1] (R) (mandatory) (1 bytes) + +**Downstream XLIN bandedges (XLINBANDSds) table**: XLINBANDSds contains pairs of indices (start\_subcarrier\_index, stop\_subcarrier\_index) for every band in which XLINpsds is reported. Each index is 2 bytes. This attribute is organized as a table, so the number of bands can be determined from the table's size. See clause 7.5.1.39.3 of [ITU-T G.997.1] (R) (mandatory) (N bands x 4 bytes) + +**Downstream FEXT coupling (XLINpsds) table**: For each given VCE port index $k$ , this parameter is a one-dimensional array of complex values in linear scale for downstream FEXT coupling coefficients $X_{\text{linds}}(f)$ originating from the loop connected to the VCE port $k$ into the loop for which $X_{\text{linds}}(f)$ is being reported. Each complex value $[a(n) + j \times b(n)]$ is represented by a 2 byte signed two's complement value $[a(n)]$ , followed by a 2 byte signed two's complement value $[b(n)]$ . This attribute is organized as a table, so the number of complex values in the array can be determined from the table's size. See clause 7.5.1.39.4 of [ITU-T G.997.1] (R) (mandatory) (N complex values $\times$ 4 bytes) + +**Upstream XLIN scale (XLINSCus)**: This parameter is the scale factor to be applied to the upstream XLINpsus values. Valid values are given in clause 7.5.1.39.5 of [ITU-T G.997.1] (R) (mandatory) (2 bytes) + +**Upstream XLIN subcarrier group size (XLINGus)**: This parameter is the number of subcarriers per group used to report XLINpsus. Valid values are given in clause 7.5.1.39.6 of [ITU-T G.997.1] (R) (mandatory) (1 bytes) + +**Upstream XLIN bandedges (XLINBANDSus) table:** XLINBANDSus contains pairs of indices (start\_subcarrier\_index, stop\_subcarrier\_index) for every band in which XLINpsus is reported. Each index is 2 bytes. This attribute is organized as a table, so the number of bands can be determined from the table's size. See clause 7.5.1.39.7 of [ITU-T G.997.1] (R) (mandatory) (N bands x 4 bytes) + +**Upstream FEXT coupling (XLINpsus) table:** For each given VCE port index $k$ , this parameter is a one-dimensional array of complex values in linear scale for upstream FEXT coupling coefficients $X_{\text{linus}}(f)$ originating from the loop connected to the VCE port $k$ into the loop for which $X_{\text{linus}}(f)$ is being reported. Each complex value $[a(n) + j \times b(n)]$ is represented by a 2 byte signed two's complement value $[a(n)]$ , followed by a 2 byte signed two's complement value $[b(n)]$ . This attribute is organized as a table, so the number of complex values in the array can be determined from the table's size. See clause 7.5.1.39.8 of [ITU-T G.997.1] (R) (mandatory) ( $N$ complex values $\times$ 4 bytes) + +**Actual vectoring mode (ACTVECTORMODE):** This parameter reports the vectoring initialization type of the line. Valid values are given in clause 7.5.1.43.1 of [ITU-T G.997.1] (R) (optional) (1 byte) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.40 Data gathering line test, diagnostic and status** + +This ME contains xDSL data gathering line test, diagnostic and status parameters. + +An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP xDSL UNI part 1. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1 ME. (R, set-by-create) (mandatory) (2 bytes) + +**Logging depth – VTU-O (LOGGING\_DEPTH\_O):** This parameter is the maximum depth of the entire data gathering event buffer at the VTU-O, in number of 6 byte data gathering records. See clause 7.5.3.1 of [ITU-T G.997.1] (R) (optional) (4 bytes) + +**Logging depth – VTU-R (LOGGING\_DEPTH\_R):** This parameter is the maximum depth of the entire data gathering event buffer at the VTU-R, in number of 6 byte data gathering records. See clause 7.5.3.2 of [ITU-T G.997.1] (R) (optional) (4 bytes) + +**Actual logging depth for reporting – VTU-O (ACT\_logging\_depth\_reporting\_O):** This parameter is the actual logging depth that is used for reporting the VTU-O event trace buffer in the CO-MIB, in number of 6 byte data gathering records. See clause 7.5.3.3 of [ITU-T G.997.1] (R) (optional) (4 bytes) + +**Actual logging depth for reporting – VTU-R (ACT\_logging\_depth\_reporting\_R):** This parameter is actual logging depth that is used for reporting the VTU-R event trace buffer over the eoc, in number of 6 byte data gathering records. See clause 7.5.3.4 of [ITU-T G.997.1] (R) (optional) (4 bytes) + +**Event trace buffer – VTU-O (EVENT\_TRACE\_BUFFER\_O) table:** This parameter is the event trace buffer containing the event records that originated at the VTU-O. See clause 7.5.3.5 of [ITU-T G.997.1] (R) (optional) (*N* bytes) + +**Event trace buffer – VTU-R (EVENT\_TRACE\_BUFFER\_R) table:** This parameter is the event trace buffer containing the event records that originated at the VTU-R. See clause 7.5.3.6 of [ITU-T G.997.1] (R) (optional) (*N* bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.7.41 EFM bonding group** + +The EFM bonding group represents a group of links that are bonded. In [IEEE 802.3], a bonding group is known as a PAF [physical medium entity (PME) aggregation function] and a link is known as a PME instance of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of an EFM bonding link. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Group ID:** This attribute is the unique number representing this bonding group. See clause C.3.1.1 of [ITU-T G.998.2]. (R, W, set-by-create) (mandatory) (6 bytes) + +**Minimum upstream group rate:** This attribute sets the minimum upstream group rate, in bits per second, for this EFM Group. This attribute is used to determine the group US rate low alarm status. The group US rate low alarm means that the aggregate upstream rate of all active links associated with this group is less than the minimum upstream group rate. The default value for this rate is zero. (R, W) (mandatory, set-by-create) (4 bytes) + +**Minimum downstream group rate:** This attribute sets the minimum downstream group rate, in bits per second, for this EFM Group. This attribute is used to determine the group DS rate low alarm status. The group DS rate low alarm means that the aggregate downstream rate of all active links associated with this group is less than the minimum downstream group rate. The default value for this rate is zero. (R, W) (mandatory, set-by-create) (4 bytes) + +**Group alarm enable:** This bit mapped attribute enables the various group alarms. A bit value of 1 means "enable". + +| Bit | Meaning | +|------------|-------------------| +| 1 (LSB) | Group down | +| 2 | Group partial | +| 3 | Group US rate low | +| 4 | Group DS rate low | + +| | | +|-----|---------------| +| 5 | 4x rate ratio | +| 6-8 | Reserved | + +(R, W, set-by-create) (mandatory) (1 byte) + +#### Actions + +Create, delete, get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-------------------|--------------------------------------------------------------------------| +| 0 | Group down | No links associated with this group are active | +| 1 | Group partial | Not all links associated with this group are active | +| 2 | Group US rate low | Aggregate upstream rate is less than the minimum upstream group rate | +| 3 | Group DS rate low | Aggregate downstream rate is less than the minimum downstream group rate | +| 4 | 4x rate ratio | In this group, ratio of max link rate to min link rate > 4 | +| 5..207 | Reserved | | + +NOTE – An "active" link means that the port is trained and fragments can flow across the link in both directions. + +### 9.7.42 EFM bonding link + +The EFM bonding link represents a link that can be bonded with other links to form a group. In [IEEE 802.3], a bonding group is known as a PAF and a link is known as a PME. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME may be associated with zero or one instance of an EFM bonding group. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. + +NOTE – This attribute has the same meaning as the Stream ID in clause C.3.1.2 of [ITU-T G.998.2], except that it cannot be changed. (R, set-by-create) (mandatory) (2 bytes) + +**Associated group ME ID:** This attribute is the ME ID of the bonding group to which this link is associated. Changing this attribute moves the link from one group to another. Setting this attribute to an ME ID that has not yet been provisioned will result in this link being placed in a single-link group that contains only this link. The default value for this attribute is the null pointer, 0xFFFF. (R, W, set-by-create) (mandatory) (2 bytes) + +**Link alarm enable:** This bit mapped attribute enables the group down and group partial alarms. A bit value of 1 means "enable". + +| Bit | Meaning | +|---------|-----------| +| 1 (LSB) | Link down | +| 2-8 | Reserved | + +(R, W, set-by-create) (mandatory) (1 bytes) + +#### Actions + +Create, delete, get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------|---------------------------------------------------------| +| 0 | Link down | Link not active. See definition in EFM bonding group ME | +| 1..207 | Reserved | | + +### 9.7.43 EFM bonding group performance monitoring history data + +This ME collects PM data as seen at the xTU-C. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the EFM bonding group. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Rx bad fragments:** Clause 45.2.3.33 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx lost fragments:** Clause 45.2.3.34 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx lost starts:** Clause 45.2.3.35 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx lost ends:** Clause 45.2.3.36 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx frames:** Number of Ethernet frames received over this group. (R) (mandatory) (4 bytes) + +**Tx frames:** Number of Ethernet frames transmitted over this group. (R) (mandatory) (4 bytes) + +**Rx bytes:** Number of bytes contained in the Ethernet frames received over this group. (R) (mandatory) (8 bytes) + +**Tx bytes:** Number of bytes contained in the Ethernet frames transmitted over this group. (R) (mandatory) (8 bytes) + +**Tx discarded frames:** Number of Ethernet frames discarded by the group transmit function. (R) (mandatory) (4 bytes) + +**Tx discarded bytes:** Number of bytes contained in the Ethernet frames discarded by the group transmit function. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------|--------------------------|-----------------------------------------| +| 0 | Rx bad fragments | 1 | +| 1 | Rx lost fragments | 2 | +| 2 | Rx lost starts | 3 | +| 3 | Rx lost ends | 4 | +| 4..207 | Reserved | | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.7.44 EFM bonding group performance monitoring history data part 2 + +This ME collects PM data as seen at the xTU-C. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the EFM bonding group. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Rx unicast frames:** Number of unicast Ethernet frames received over this group. (R) (mandatory) (4 bytes) + +**Tx unicast frames:** Number of unicast Ethernet frames transmitted over this group. (R) (mandatory) (4 bytes) + +**Rx unicast bytes:** Number of bytes contained in the unicast Ethernet frames received over this group. (R) (mandatory) (8 bytes) + +**Tx unicast bytes:** Number of bytes contained in the unicast Ethernet frames transmitted over this group. (R) (mandatory) (8 bytes) + +**Rx broadcast frames:** Number of broadcast Ethernet frames received over this group. (R) (mandatory) (4 bytes) + +**Tx broadcast frames:** Number of broadcast Ethernet frames transmitted over this group. (R) (mandatory) (4 bytes) + +**Rx broadcast bytes:** Number of bytes contained in the broadcast Ethernet frames received over this group. (R) (mandatory) (8 bytes) + +**Tx broadcast bytes:** Number of bytes contained in the broadcast Ethernet frames transmitted over this group. (R) (mandatory) (8 bytes) + +**Rx multicast frames:** Number of multicast Ethernet frames received over this group. (R) (mandatory) (4 bytes) + +**Tx multicast frames:** Number of multicast Ethernet frames transmitted over this group. (R) (mandatory) (4 bytes) + +**Rx multicast bytes:** Number of bytes contained in the multicast Ethernet frames received over this group. (R) (mandatory) (8 bytes) + +**Tx multicast bytes:** Number of bytes contained in the multicast Ethernet frames transmitted over this group. (R) (mandatory) (8 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +None. + +### **9.7.45 EFM bonding link performance monitoring history data** + +This ME collects PM data as seen at the xTU-C. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the EFM bonding link. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Rx errored fragments:** Clause 45.2.3.29 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx small fragments:** Clause 45.2.3.30 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx large fragments:** Clause 45.2.3.31 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx discarded fragments:** Clause 45.2.3.32 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx FCS errors:** Clause 45.2.6.11 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx coding errors:** Clause 45.2.6.12 of [IEEE 802.3]. (R) (mandatory) (4 bytes) + +**Rx fragments:** Number of fragments received over this link. (R) (mandatory) (4 bytes) + +**Tx fragments:** Number of fragments transmitted over this link. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------|--------------------------|-----------------------------------------| +| 0 | Rx errored fragments | 1 | +| 1 | Rx small fragments | 2 | +| 2 | Rx large fragments | 3 | +| 3 | Rx discarded fragments | 4 | +| 4 | Rx FCS errors | 5 | +| 5 | Rx coding errors | 6 | +| 6-207 | Reserved | | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.7.46 EFM bonding port performance monitoring history data + +This ME collects PM data as seen at the xTU-C. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Rx frames:** Number of Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx frames:** Number of Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Rx bytes:** Number of bytes contained in the Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx bytes:** Number of bytes contained in the Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Tx discarded frames:** Number of Ethernet frames discarded by the port transmit function. (R) (mandatory) (4 bytes) + +**Tx discarded bytes:** Number of bytes contained in the Ethernet frames discarded by the port transmit function. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------------------------------------------------------------------------------------------------------------------------|--------------------------|-----------------------------------------| +| 0 | Bad fragments | 1 | +| 1 | Lost fragments | 2 | +| 2 | Lost starts | 3 | +| 3 | Lost ends | 4 | +| 4-207 | Reserved | | +| NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. | | | + +### 9.7.47 EFM bonding port performance monitoring history data part 2 + +This ME collects PM data as seen at the xTU-C. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with an xDSL UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The two MSBs of the first byte are the bearer channel ID. Excluding the first 2 bits of the first byte, the remaining part of the ME ID is identical to that of this ME's parent PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Rx unicast frames:** Number of unicast Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx unicast frames:** Number of unicast Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Rx unicast bytes:** Number of bytes contained in the unicast Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx unicast bytes:** Number of bytes contained in the unicast Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Rx broadcast frames:** Number of broadcast Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx broadcast frames:** Number of broadcast Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Rx broadcast bytes:** Number of bytes contained in the broadcast Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx broadcast bytes:** Number of bytes contained in the broadcast Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Rx multicast frames:** Number of multicast Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx multicast frames:** Number of multicast Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +**Rx multicast bytes:** Number of bytes contained in the multicast Ethernet frames received over this port. (R) (mandatory) (4 bytes) + +**Tx multicast bytes:** Number of bytes contained in the multicast Ethernet frames transmitted over this port. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +None. + +### **9.7.48 Physical path termination point UNI part 3 (FAST)** + +This ME represents the point in the ONU where physical paths terminate on a FAST [ITU-T G.9700, ITU-T G.9701] DPU modem (FTU-O). + +The ONU creates or deletes an instance of this ME at the same time it creates or deletes the corresponding PPTP xDSL UNI part 1 intended to serve a FAST connection, as per [ITU-T G.997.2]. + +#### *Relationships* + +An instance of this ME is associated with each instance of a real or preprovisioned FAST port + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**FAST line configuration profile:** This attribute points to an instance of the FAST line configuration profiles (part 1, 2, 3 and 4) MEs, also to FAST vectoring line configuration extension MEs. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (mandatory) (2 bytes) + +**FAST data path configuration profile:** This attribute points to an instance of the FAST data configuration profile that defines data path parameters. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (optional) (2 bytes) + +**FAST channel configuration profile for bearer channel 0 downstream:** This attribute points to an instance of the FAST channel configuration profile that defines channel parameters. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer. (R, W) (optional) (2 bytes) (R, W) (optional) (2 bytes) + +**FAST channel configuration profile for bearer channel 0 upstream:** This attribute points to an instance of the FAST channel configuration profile that defines channel parameters. Upon ME instantiation, the ONU sets this attribute to 0, a null pointer (R, W) (optional) (2 bytes) + +#### *Actions* + +Get, set + +#### Notifications + +None. + +### 9.7.49 FAST line configuration profile part 1 + +This ME extends the xDSL line configuration MEs with attributes that are unique to FAST (see [ITU-T G.9700] and [ITU-T G.9701]). The attributes of this ME are defined in [ITU-T G.997.2]. An instance of this ME is created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with a PPTP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (The client PPTP UNI part 3 refers to the entire set of line configuration parts). + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**ITU-T G.9701 profiles enabling (PROFILES):** This attribute contains the ITU-T G.9701 profiles to be allowed by the xTU-C. See clause 7.1.0.1 of [ITU-T G.997.2]. It is coded in a bit map representation (0 if not allowed, 1 if allowed) with the following definition: + +| Bit | Meaning | +|---------|---------------------------| +| 1 (LSB) | ITU-T G.9701 profile 106a | +| 2 | ITU-T G.9701 profile 106b | +| 3 | ITU-T G.9701 profile 106c | +| 4 | ITU-T G.9701 profile 212a | +| 5 | ITU-T G.9701 profile 212c | + +(R, W, set-by-create) (mandatory) (1 byte) + +**Symbol periods per TDD frame (MF):** This attribute specifies the total number of symbol periods in a TDD frame. See clause 10.5 of [ITU-T G.9701]. Valid values are 23 and 36. (R, W, set-by-create) (mandatory) (1 byte) + +**Symbol periods per TDD frame dedicated for downstream transmission (Mds):** This attribute specifies the total number of symbol positions in a TDD frame allocated for downstream transmission. The total number of symbol positions in a TDD frame allocated for upstream transmission is calculated as $M_{us} = MF - 1 - M_{ds}$ . See clause 10.5 of [ITU-T G.9701]. Valid values range from 10 to 32 (if $MF = 36$ ) and from 6 to 19 (if $MF = 23$ ). The default value is 28 (if $MF = 36$ ) and 18 (if $MF = 23$ ). See clause 7.1.1.2 of [ITU-T G.997.2]. (R, W, set-by-create) (mandatory) (1 byte) + +**Downstream maximum aggregate transmit power (MAXATPds):** This attribute specifies the maximum aggregate transmit power at the U-O2 reference point in the downstream direction during initialization and showtime (in decibel-milliwatts). Valid values range from 5 to 31 in steps of 1 s. See clause 7.1.2.1 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream maximum aggregate transmit power (MAXATPus):** This attribute specifies the maximum aggregate transmit power at the U-R2 reference point in the upstream direction during initialization and showtime (in decibel-milliwatts). + +The attribute value ranges from 0 (−31.0 dBm) to 620 (+31.0 dBm) in steps of 0.1 dBm. See clause 7.1.2.2 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Downstream subcarrier masking (CARMASKds) table:** This attribute specifies the masked subcarrier bands in the downstream direction. All subcarriers within the band, i.e., with indices higher than or equal to the start subcarrier index and lower than or equal to the stop subcarrier index, are masked, i.e., have a transmit power set to zero (linear scale) + +The CARMASK attribute is a table where each entry comprises: + +- an entry number field (1 byte, first entry numbered 1); +- band start subcarrier index (2 bytes); +- band stop subcarrier index (2 bytes). + +Subcarrier index valid values range from 0 to 4095 (subcarrier index 0 to 4095). By default, no masked subcarriers, the table is empty. Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier references to 0xFFFF implies deletion from the table, if present. See clause 7.1.2.3 of [ITU-T G.997.2]. + +(R, W) mandatory (5\*N bytes) + +**Upstream subcarrier masking (CARMASKus) table:** This attribute specifies the masked subcarrier bands in the upstream direction. All subcarriers within the band, i.e., with indices higher than or equal to the start subcarrier index and lower than or equal to the stop subcarrier index, have a transmit power set to zero (linear scale). + +The CARMASK attribute is a table where each entry comprises: + +- an entry number field (1 byte, first entry numbered 1); +- band start subcarrier index (2 bytes); +- band stop subcarrier index (2 bytes). + +Valid value of band subcarrier index ranges from 0 to 4095. By default, no masked subcarriers, the table is empty. Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier references to 0xFFFF implies deletion from the table, if present. See clause 7.1.2.4 of [ITU-T G.997.2]. + +(R, W) (mandatory) (5\*N bytes) + +**Downstream PSD mask (PSDMASKds) table:** This attribute specifies the downstream PSD mask applicable at the U-O2 reference point. Requirements for a valid PSDMASKds are defined in [ITU-T G.9701] clauses 7.3.1.1.2.1 and 7.3.1.1.2.2. + +Each table entry in this attribute comprises: + +- an entry number field (1 byte, first entry numbered 1); +- a subcarrier index field, denoted $t$ (2 bytes); +- a PSD mask level field (1 byte). + +The valid value of the subcarrier index ranges from 0 to 4095. The valid values of PSD level range from 0 (0 dBm/Hz) to 255 (−127.5 dBm/Hz), with a granularity of −0.5 dBm/Hz. Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier + +references to 0xFFFF implies deletion from the table, if present. See clause 7.1.2.5 of [ITU-T G.997.2]. + +(R, W) (mandatory) ( $4 * N$ $N \leq 32$ bytes) + +**Upstream PSD mask (PSDMASKus) table:** This attribute specifies the upstream PSD mask applicable at the U-R2 reference point. Requirements for a valid PSDMASKds are defined in [ITU-T G.9701] clauses 7.3.1.1.2.1 and 7.3.1.1.2.2. + +Each table entry in this attribute comprises: + +- an entry number field (1 byte, first entry numbered 1); +- a subcarrier index field, denoted $t$ (2 bytes); +- a PSD mask level field (1 byte). + +The valid values of the subcarrier index range from 0 to 4095. The valid value of PSD level ranges from 0 (0 dBm/Hz) to 255 ( $-127.5$ dBm/Hz), with a granularity of $-0.5$ dBm/Hz. Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier references to 0xFFFF implies deletion from the table, if present. See clause 7.1.2.6 of [ITU-T G.997.2]. (R, W) (mandatory) ( $4 * N$ $N \leq 32$ bytes) + +**RFI bands (RFIBANDS) table:** This attribute specifies the bands where the PSD shall be reduced as specified in [ITU-T G.9701] clause 7.3.1.2. + +The table where each entry comprises: + +- an entry number field (1 byte, first entry numbered 1); +- subcarrier index 1 field (2 bytes); +- subcarrier index 2 field (2 bytes). + +The valid value of the band subcarrier index ranges from 0 to 4095. By default, no masked subcarriers, the table is empty. Setting a table entry with non-zero subcarrier references implies insertion into the table. Setting an entry's subcarrier references to 0xFFFF implies deletion from the table, if present. See clause 7.1.2.7 of [ITU-T G.997.2]. + +(R, W) (mandatory) ( $5 * N$ bytes) + +**International amateur radio bands (IARBANDS):** This attribute specifies for each international amateur radio (IAR) band whether transmit PSD reduction is enabled or disabled in that band. + +Bit representation: + +- 0 International amateur radio band 1800-2000 kHz +- 1 International amateur radio band 3500-4000 kHz +- 2 International amateur radio band 7000-7300 kHz +- 3 International amateur radio band 10100-10150 kHz +- 4 International amateur radio band 14000-14350 kHz +- 5 International amateur radio band 18068-18168 kHz +- 6 International amateur radio band 21000-21450 kHz +- 7 International amateur radio band 24890-24990 kHz +- 8 International amateur radio band 28000-29700 kHz +- 9 International amateur radio band 50000-54000 kHz + +10 International amateur radio band 69900-70500 kHz + 11 International amateur radioμ band 144000-148000 kHz + 12 International amateur radio band 5351.5-5366.5 kHz + Default value: All IAR bands disabled (no PSD reduction) + See clause 7.1.2.8 of [ITU-T G.997.2] + (R, W) (mandatory) (2 bytes) + +**Upstream power back-off reference PSD (UPBOPSDA):** This attribute specifies the parameter $a$ for the UPBO reference PSD used to compute the UPBO for the upstream frequency band. The valid values range from 0 (40 dBm/Hz) to 4095 (80.95 dBm/Hz), with a granularity of $-0.01$ dBm/Hz. See clause 7.1.2.9 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream power back-off reference PSD (UPBOPSDB):** This attribute specifies the parameter $b$ for the UPBO reference PSD used to compute the UPBO for the upstream frequency band. The valid values range from 0 (0 dBm/Hz) to 4095 (40.95 dBm/Hz), with a granularity of $-0.01$ dBm/Hz. See clause 7.1.2.10 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream electrical length (UPBOKL):** This attribute specifies the electrical length $kl_0$ (expressed in decibels at 1 MHz). The valid values range from 0 (0 dB) to 1280 (128 dB), with a granularity of $-0.1$ dB. See clause 7.1.2.11 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Force electrical length (UPBOKLF):** This Boolean attribute specifies whether the FTU-R is forced to use the electrical length $kl_0 = \text{UPBOKL}$ to compute the UPBOMASK. If not forced, the FTUs determine the electrical length $kl_0$ : true specifies that the FTU-R is forced to use, false specifies not forced. See clause 7.1.2.12 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**UPBO reference electrical length per band (UPBOKLREF):** This attribute specifies the UPBO reference electrical length $kl_{0\_REF}$ used to compute the UPBO for the Equalized FEXT UPBO method. The valid values range from 18 (1.8) to 635 (63.5 dB), with a granularity of $-0.1$ dB. The special value 0 indicates that the Equal PSD UPBO method is used. See clause 7.1.2.13 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, get next, set +set table (optional) + +#### *Notifications* + +None. + +### **9.7.50 FAST line configuration profile part 2** + +This ME extends the FAST line configuration MEs. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with a PPTP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID. (The client PPTP UNI part 3 refers to the entire set of line configuration parts). + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**Downstream target noise margin (TARSNRMds):** This attribute specifies the downstream target noise margin for the channel initialization policy. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of –0.1 dB. See clause 7.1.3.1 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream target noise margin (TARSNRMus):** This attribute specifies the upstream target noise margin used in the channel initialization policy. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of –0.1 dB. See clause 7.1.3.2 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Deprecated:** This attribute is not used. It should be set to 0 by the OLT and ignored by the ONU. (R, W) (mandatory) (2 bytes) + +**Upstream maximum noise margin (MAXSNRMus):** This attribute specifies the upstream maximum noise margin used in the channel initialization policy. The special value indicates there is no maximum bound for the upstream noise margin (i.e., the upstream maximum noise margin is infinite). The valid values range 511 (special value) and 0..310 (0 to 31 dB) in steps of –0.1 dB. See clause 7.1.3.3 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Downstream minimum noise margin (MINSNRMsds):** This attribute specifies the downstream minimum noise margin the FTU-R receiver shall tolerate. If the downstream noise margin (SNRMsds) falls below this level, the FTU-R requests the FTU-O to increase the FTU-O transmit power. If an increase to FTU-O transmit power is not possible, an LOM defect occurs. Upon persistency of the LOM defect, the FTU-R triggers a re-initialization. See clause 12.1.4.2 of [ITU-T G.9701]. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of –0.1 dB. See clause 7.1.3.4 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream minimum noise margin (MINSNRMus):** This attribute specifies the upstream minimum noise margin the FTU-O receiver shall tolerate. If the upstream noise margin (SNRMus) falls below this level, the FTU-O requests the FTU-R to increase the FTU-R transmit power. If an increase to FTU-R transmit power is not possible, an LOM defect occurs. Upon persistency of the LOM defect, the FTU-O triggers a re-initialization. See clause 12.1.4.2 of [ITU-T G.9701]. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of –0.1 dB. See clause 7.1.3.5 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Downstream target noise margin for RMC (TARSNRM-RMCds):** This attribute specifies the downstream RMC noise margin (SNRMRMCds) that the FTU-R receiver shall achieve, relative to the BER requirement, or better, to successfully complete initialization. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of 0.1 dB. See clause 7.1.6.1 of [ITU-T G.997.2] for detailed specification. (R, W) (mandatory) (2 bytes) + +**Upstream target noise margin (TARSNRM-RMCus):** This attribute specifies the upstream RMC noise margin (SNRMRMCus) that the FTU-O receiver shall achieve, + +relative to the BER requirement, or better, to successfully complete initialization. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of 0.1 dB. See clause 7.1.6.2 of [ITU-T G.997.2] for detailed specification. (R, W) (mandatory) (2 bytes) + +**Downstream minimum noise margin for RMC (MINSNRM-RMCds):** This attribute defines the downstream minimum noise margin the FTU-R receiver tolerates for the RMC. If the downstream RMC noise margin (SNRM-RMCds) falls below this level, the FTU-R initiates the RPA procedure. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of 0.1 dB. See clause 7.1.6.3 of [ITU-T G.997.2] for detailed specification. (R, W) (mandatory) (2 bytes) + +**Upstream minimum noise margin for RMC (MINSNRM-RMCus):** This attribute defines the upstream minimum noise margin the FTU-O receiver tolerates for the RMC. If the downstream RMC noise margin (SNRM-RMCus) falls below this level, the FTU-O initiates the RPA procedure. The valid values range from 0 (0 dB) to 310 (31 dB) in steps of 0.1 dB. See clause 7.1.6.4 of [ITU-T G.997.2] for detailed specification. (R, W) (mandatory) (2 bytes) + +**Downstream maximum bitloading for RMC (MAXBL-RMCds):** This attribute defines the maximum allowed bit-loading for the downstream RMC subcarriers. The valid values range from 2 to 6. See clause 7.1.6.5 of [ITU-T G.997.2] for detailed specification. (R, W) (mandatory) (1 byte) + +**Upstream maximum bitloading for RMC (MAXBL-RMCus):** This attribute defines the maximum allowed bit-loading for the upstream RMC subcarriers. The valid values range from 2 to 6. See clause 7.1.6.6 of [ITU-T G.997.2] for detailed specification. (R, W) (mandatory) (1 byte) + +**Downstream RMCR *lor* persistency trigger (RMCR\_LOR\_TRIGGERds):** This attribute defines the persistency period of a downstream RMCR *lor* defect before the RMC is declared severely degraded. The value 0 is a special value that indicates that the RMCR procedure is disabled. See clause 7.1.12.1 of [ITU-T G.997.2] for detailed specification. (R, W) (optional) (1 byte) + +**Upstream RMCR *lor* persistency trigger (RMCR\_LOR\_TRIGGERus):** This attribute defines the persistency period of a upstream RMCR *lor* defect before the RMC is declared severely degraded. The value 0 is a special value that indicates that the RMCR procedure is disabled. See clause 7.1.12.1 of [ITU-T G.997.2] for detailed specification. (R, W) (optional) (1 byte) + +#### ***Actions*** + +Create, delete, get, set + +#### ***Notifications*** + +None. + +### **9.7.51 FAST line configuration profile part 3** + +This ME extends the FAST line configuration MEs. An instance of this ME is created and deleted by the OLT. + +#### ***Relationships*** + +An instance of this ME is associated with a PPTP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (The client PTP UNI part 3 refers to the entire set of line configuration parts). + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All xDSL and VDSL2 line configuration profiles and extensions that pertain to a given PTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**Downstream upshift noise margin (SRA-USNRMds):** If the downstream noise margin (SNRMds) is above the downstream upshift noise margin and stays above that for more than the time specified by the downstream minimum upshift rate adaptation interval (SRA-UTIMEds), the FTU-R autonomously attempts to increase the downstream net data rate (NDR). The valid values range from 0 (0 dB) to 310 (31 dB) in steps of $-0.1$ dB. See clause 7.1.4.1 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream upshift noise margin (SRA-USNRMus):** If the upstream noise margin (SNRMus) is above the upstream upshift noise margin and stays above that for more than the time specified by the upstream minimum upshift rate adaptation interval (SRA-UTIMEds), the FTU-R autonomously attempts to increase the upstream net data rate (NDR). The valid values range from 0 (0 dB) to 310 (31 dB) in steps of $-0.1$ dB. See clause 7.1.4.2 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Downstream minimum time interval for upshift SRA (SRA-UTIMEds):** This attribute specifies the interval of time the downstream noise margin (SNRMds) should stay above the downstream upshift noise margin (SRA-USNRMds) before the FTU-R autonomously attempts to increase the downstream net data rate (NDRds). The valid values range from 0 to 16383 s. See clause 7.1.4.3 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream minimum time interval for upshift SRA (SRA-UTIMEus):** This attribute specifies the interval of time the upstream noise margin (SNRMus) should stay above the upstream upshift noise margin (SRA-USNRMus) before the FTU-O autonomously attempts to increase the upstream net data rate (NDRus). The valid values range from 0 to 16383 s. See clause 7.1.4.4 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Downstream downshift noise margin (SRA-DSNRMds):** If the downstream noise margin (SNRMds) is below the downstream downshift noise margin and stays below that for more than the time specified by the downstream minimum downshift rate adaptation interval (SRA-DTIMEds), the FTU-R autonomously attempts to decrease the downstream net data rate (NDRds). The valid values range from 0 (0 dB) to 310 (31 dB) in steps of $-0.1$ dB. See clause 7.1.4.5 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Upstream downshift noise margin (SRA-DSNRMus):** If the upstream noise margin (SNRMus) is below the upstream downshift noise margin and stays below that for more than the time specified by the upstream minimum downshift rate adaptation interval (SRA-DTIMEus), the FTU-O autonomously attempts to decrease the upstream net data rate (NDRus). The valid values range from 0 (0 dB) to 310 (31 dB) in steps of $-0.1$ dB. See clause 7.1.4.6 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +- Downstream minimum time interval for downshift SRA (SRA-DTIMEds):** This attribute specifies the interval of time the downstream noise margin (SNRMds) should stay below the downstream downshift noise margin (SRA-DSNRMds) before the FTU-R autonomously attempts to decrease the downstream net data rate (NDRds). The valid values range from 0 to 16383 s. See clause 7.1.4.7 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) +- Upstream minimum time interval for downshift SRA (SRA-DTIMEus):** This attribute specifies the interval of time the upstream noise margin (SNRMus) should stay below the upstream downshift noise margin (SRA-DSNRMus) before the FTU-O autonomously attempts to decrease the upstream net data rate (NDRus). The valid values range from 0 to 16383 s. See clause 7.1.4.8 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) +- Downstream FRA time window (FRA-TIMEds):** In the standard FRA triggering criteria. See clause 13.3.1.1 of [ITU-T G.9701] for the downstream direction. The valid values range from 1 to 8 (if MF = 36) and from 1 to 12 (if MF = 23). See clause 7.1.5.1 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) +- Upstream FRA time window (FRA-TIMEus):** This attribute specifies the duration of the time window used in the standard FRA triggering criteria. See clause 13.3.1.1 of [ITU-T G.9701] for the upstream direction. The valid values range from 1 to 8 (if MF = 36) and from 1 to 12 (if MF = 23). See clause 7.1.5.2 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) +- Downstream FRA minimum percentage of degraded tones (FRA-NTONESds):** This attribute specifies the minimum percentage of loaded subcarriers (i.e., subcarriers with $b_i > 0$ ) that are detected as degraded throughout a time window equal to FRA-TIMEds in order to arm the first FRA triggering criteria. See clause 13.3.1.1.1.5 of [ITU-T G.9701] in the downstream direction. The valid values range from 1 to 100. The special value 0 indicates that monitoring of the percentage of degraded subcarriers is disabled. See clause 7.1.5.3 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) +- Upstream FRA minimum percentage of degraded tones (FRA-NTONESus):** This attribute specifies the minimum percentage of loaded subcarriers (i.e., subcarriers with $b_i > 0$ ) that are detected as degraded throughout a time window equal to FRA-TIMEus in order to arm the first FRA triggering criteria. See clause 13.3.1.1.1.5 of [ITU-T G.9701] in the upstream direction. The valid values range from 1 to 100. The special value 0 indicates that monitoring of the percentage of degraded subcarriers is disabled. See clause 7.1.5.4 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) +- Downstream FRA number of uncorrectable DTU (FRA-RTXUCds):** This attribute specifies the minimum number of rtx-uc anomalies received throughout a time window equal to FRA-TIMEds in order to arm the second FRA triggering criteria. See clause 13.3.1.1.1.5 of [ITU-T G.9701] in the downstream direction. The valid values range from 1 to 1023. The special value 0 indicates that monitoring of the number of rtx-uc anomalies is disabled. See clause 7.1.5.5 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) +- Upstream FRA number of uncorrectable DTU (FRA-RTXUCus):** This attribute specifies the minimum number of rtx-uc anomalies received throughout a time window equal to FRA-TIMEus in order to arm the second FRA triggering criteria. See clause 13.3.1.1.1.5 of [ITU-T G.9701] in the upstream direction. The valid values range from 1 to 1023. The special value 0 indicates that monitoring of + +the number of rtx-uc anomalies is disabled. See clause 7.1.5.6 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) + +**Downstream vendor discretionary FRA triggering criteria (FRA-VENDISCds):** This Boolean attribute specifies whether vendor discretionary FRA triggering criteria may be used (enabled) or not (disabled) in the downstream direction. See clause 7.1.5.7 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**Upstream vendor discretionary FRA triggering criteria (FRA-VENDISCus):** This Boolean attribute specifies whether vendor discretionary FRA triggering criteria may be used (enabled) or not (disabled) in the upstream direction. See clause 7.1.5.8 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.7.52 FAST line configuration profile part 4** + +This ME extends the FAST line configuration MEs. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with a PTP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID (The client PTP xDSL UNI part 3 refers to the entire set of line configuration parts). + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**Downstream los defect persistency (LOS\_PERSISTENCYds):** This attribute specifies the downstream los defect persistency for triggering a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]) at the FTU-R receiver, as part of the re-initialization policy. Valid values range from 1 (0.1 s) to 20 (2 s) in steps of 0.1 s. See clause 7.1.8.1 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Upstream los defect persistency (LOS\_PERSISTENCYus):** This attribute specifies the upstream los defect persistency for triggering a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]) at the FTU-O receiver, as part of the re-initialization policy. Valid values range from 1 (0.1 s) to 20 (2 s) in steps of 0.1 s. See clause 7.1.8.2 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Downstream lom defect persistency (LOM\_PERSISTENCYds):** This attribute specifies the downstream LOM defect persistency for triggering a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]) at the FTU-R receiver, as part of the re-initialization policy. Valid values range from 2 s to 20 s. See clause 7.1.8.3 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Upstream lom defect persistency (LOM\_PERSISTENCYus):** This attribute specifies the upstream LOM defect persistency for triggering a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]) at the FTU-O receiver, as part of the + +re-initialization policy. Valid values range from 2 s to 20 s. See clause 7.1.8.4 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Downstream lor defect persistency (LOR\_PERSISTENCYds):** This attribute specifies the downstream lor defect persistency for triggering a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]) at the FTU-R receiver, as part of the re-initialization policy. Valid values range from 1 (0.1 s) to 20 (2 s) in steps of 0.1 s. See clause 7.1.8.5 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Upstream lor defect persistency (LOR\_PERSISTENCYus):** This attribute specifies the upstream lor defect persistency for triggering a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]) at the FTU-O receiver, as part of the re-initialization policy. Valid values range from 1 (0.1 s) to 20 (2 s) in steps of 0.1 s. See clause 7.1.8.6 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Downstream re-initialization time threshold (REINIT\_TIME\_THRESHOLDds):** This attribute specifies the downstream threshold for the SES and eoc timeout conditions for declaring a High\_BER event (see clause 12.1.4.3.4 of [ITU-T G.9701]) at the FTU-R receiver, as part of the re-initialization policy. Valid values range from 5 s to 30 s. See clause 7.1.8.7 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Upstream re-initialization time threshold (REINIT\_TIME\_THRESHOLDus):** This attribute specifies the upstream threshold for the SES and eoc timeout conditions for declaring a High\_BER event (see clause 12.1.4.3.4 of [ITU-T G.9701]) at the FTU-O receiver, as part of the re-initialization policy. Valid values range from 5 s to 31 s. See clause 7.1.8.8 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Downstream low ETR threshold (LOW\_ETR\_THRESHOLDds):** This attribute specifies the downstream threshold for the low ETR condition for declaring a High\_BER event (see clause 12.1.4.3.4) at the FTU-R receiver, as part of the re-initialization policy. Valid values range from 1 s to 30 s. The special value 0 indicates that no High\_BER event is declared based on ETR being below the ETR\_min. See clause 7.1.8.9 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +**Upstream low ETR threshold (LOW\_ETR\_THRESHOLDus):** This attribute specifies the upstream threshold for the low ETR condition for declaring a High\_BER event (see clause 12.1.4.3.4) at the FTU-O receiver, as part of the re-initialization policy. Valid values range from 1 s to 30 s. The special value 0 indicates that no High\_BER event is declared based on ETR being below the ETR\_min. See clause 7.1.8.10 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.7.53 FAST channel configuration profile, part 1** + +This ME contains the FAST channel configuration profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with a PTPP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID. (The client PPTP xDSL UNI part 3 refers to the entire set of line configuration parts). + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) +- Upstream maximum net data rate (MAXNDRus):** This attribute specifies the value of the maximum upstream net data rate. See clause 11.4.2.2 of [ITU-T G.9701]. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.2.1.1 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Upstream minimum expected throughput (MINETRus):** This attribute specifies the value of the minimum upstream expected throughput. See clause 11.4.2.1 of [ITU-T G.9701]. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.2.1.2 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Upstream maximum gamma data rate (MAXGDRus):** This attribute specifies the maximum upstream value of the GDR (see clause 7.11.1.3). The GDR shall not exceed MAXGDR at the start of showtime and during showtime. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.2.1.3 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Upstream minimum gamma data rate (MINGDRus):** This attribute specifies the minimum upstream value of the GDR (see clause 7.11.1.3). The GDR may be lower than MINGDR. If the GDR is lower than MINGDR at initialization or when GDR becomes lower than MINGDR during showtime, a TCA occurs. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.2.1.4 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Upstream maximum delay (DELAYMAXus):** This attribute specifies the maximum allowed delay for upstream retransmission. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter delay\_max is set to the same value as the maximum delay. See clause 11.4.2.3 of [ITU-T G.9701]. Valid values range from 4 (1 ms) to 252 (63 ms) in steps of 0.25 ms. See clause 7.2.2.1 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Upstream minimum impulse noise protection against SHINE (INPMIN\_SHINEus):** This attribute specifies the minimum upstream INP against SHINE. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter INP\_min\_shine is set to the same value as the minimum INP against SHINE. See clause 11.4.2.4 of [ITU-T G.9701]. Valid values range from 0 to 520 (520 symbol periods). See clause 7.2.2.2 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) +- Upstream SHINE ratio (SHINERATIOus):** This attribute specifies the upstream SHINE ratio that is used in the definition of the expected throughput rate (ETR). See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter SHINERatio is set to the same value as the SHINE ratio. See clause 11.4.2.5 of [ITU-T G.9701]. The value is expressed in units of 0.001. Valid values range from 0 to 100 (0.01) in steps of 0.001. See clause 7.2.2.3 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**Upstream minimum impulse noise protection against REIN (INPMIN\_REINus)**: This attribute specifies the minimum upstream INP against REIN. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter INP\_min\_rein is set to the same value as the minimum INP against REIN. See clause 11.4.2.6 of [ITU-T G.9701]. Valid values range from 0 to 63 (63 symbol periods). See clause 7.2.2.4 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**Upstream REIN Inter-arrival time (IAT\_REINus)**: This attribute specifies the upstream REIN IAT. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter iat\_rein\_flag is set to the same value as the REIN IAT. See clause 11.4.2.7 of [ITU-T G.9701]. + +The REIN IAT is specified via the following values: + +- 1 100 Hz; +- 2 120 Hz; +- 3 360 Hz. + +See clause 7.2.2.5 of [ITU-T G.997.2]. + +(R, W) (mandatory) (1 byte) + +**Upstream minimum Reed-Solomon RFEC/NFEC ratio (RNRATIOus)**: This attribute specifies the minimal required ratio, RFEC/NFEC, of Reed-Solomon code parameters in the upstream direction. The ITU-T G.9701 control parameter rnratio is set to the same value as the minimum Reed-Solomon RFEC/NFEC ratio. See clause 11.4.2.8 of [ITU-T G.9701]. The value is expressed in units of 1/32, Valid values range from 0 to 8 (1/4). See clause 7.2.2.6 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**RTX-TC testmode (RTX\_TESTMODE)**: This Boolean attribute specifies whether the retransmission test mode defined in clause 9.8.3.1.2 [ITU-T G.9701] is enabled (true) or disabled (disabled). See clause 7.2.2.7 of [ITU-T G.997.2]. (R, W) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +#### **9.7.53.1 FAST channel configuration profile, part 2** + +This ME contains the FAST channel configuration profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +##### *Relationships* + +An instance of this ME is associated with a PPTP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID. (The client PPTP UNI part 3 refers to the entire set of line configuration parts). + +##### *Attributes* + +**Managed entity ID**: This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +- Downstream maximum net data rate (MAXNDRds):** This attribute specifies the value of the downstream maximum net data rate. See clause 11.4.2.2 of [ITU-T G.9701]. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32} - 1$ kbit/s). See clause 7.2.1.1 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Downstream minimum expected throughput (MINETRds):** This attribute specifies the value of the downstream minimum expected throughput. See clause 11.4.2.1 of [ITU-T G.9701]. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32} - 1$ kbit/s). See clause 7.2.1.2 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Downstream maximum gamma data rate (MAXGDRds):** This attribute specifies the maximum value of the downstream GDR (see clause 7.11.1.3). The GDR shall not exceed MAXGDR at the start of showtime and during showtime. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32} - 1$ kbit/s). See clause 7.2.1.3 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Downstream minimum gamma data rate (MINGDRds):** This attribute specifies the minimum value of the downstream GDR (see clause 7.11.1.3). The GDR may be lower than MINGDR. If the GDR is lower than MINGDR at initialization or when GDR becomes lower than MINGDR during showtime, a TCA occurs. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32} - 1$ kbit/s). See clause 7.2.1.4 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Downstream maximum delay (DELAYMAXds):** This attribute specifies the maximum allowed delay for downstream retransmission. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter delay\_max is set to the same value as the maximum delay. See clause 11.4.2.3 of [ITU-T G.9701]. Valid values range from 4 (1 ms) to 252 (63 ms) in steps of 0.25 ms. See clause 7.2.2.1 of [ITU-T G.997.2]. (R, W) (mandatory) (4 bytes) +- Downstream minimum impulse noise protection against SHINE (INPMIN\_SHINEds):** This attribute specifies the minimum downstream INP against SHINE. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter INP\_min\_shine is set to the same value as the minimum INP against SHINE. See clause 11.4.2.4 of [ITU-T G.9701]. Valid values range from 0 to 520 (520 symbol periods). See clause 7.2.2.2 of [ITU-T G.997.2]. (R, W) (mandatory) (2 bytes) +- Downstream SHINE ratio (SHINERATIOds):** This attribute specifies the downstream SHINE ratio that is used in the definition of the expected throughput rate (ETR). See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter SHINERatio is set to the same value as the SHINE ratio. See clause 11.4.2.5 of [ITU-T G.9701]. The value is expressed in units of 0.001. Valid values range from 0 to 100 (0.01) in steps of 0.001. See clause 7.2.2.3 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) +- Downstream minimum impulse noise protection against REIN (INPMIN\_REINds):** This attribute specifies the minimum downstream INP against REIN. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter INP\_min\_rein is set to the same value as the minimum INP against REIN. See clause 11.4.2.6 of [ITU-T G.9701]. Valid values range from 0 to 63 (63 symbol periods). See clause 7.2.2.4 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) +- Downstream REIN Inter-arrival time (IAT\_REINds):** This attribute specifies the downstream REIN IAT. See clause 9.8 of [ITU-T G.9701]. The ITU-T G.9701 control parameter iat\_rein\_flag is set to the same value as the REIN IAT. See clause 11.4.2.7 of [ITU-T G.9701]. + +The REIN IAT is specified via the following values: + +- 1 100 Hz +- 2 120 Hz +- 3 360 Hz + +See clause 7.2.2.5 of [ITU-T G.997.2]. + +(R, W) (mandatory) (1 byte) + +**Downstream minimum Reed-Solomon RFEC/NFEC ratio (RNRATIODs)**: This attribute specifies the minimal required ratio, RFEC/NFEC, of Reed-Solomon code parameters in the downstream. The ITU-T G.9701 control parameter *rnratio* is set to the same value as the minimum Reed-Solomon RFEC/NFEC ratio. See clause 11.4.2.8 of [ITU-T G.9701]. The value is expressed in units of 1/32. Valid values range from 0 to 8 (1/4). See clause 7.2.2.6 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +##### *Actions* + +Create, delete, get, set + +##### *Notifications* + +None. + +### **9.7.54 FAST data path configuration profile** + +This ME contains FAST the data path configuration profile for an xDSL UNI. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the PPTP UNI part 3. + +The overall FAST line configuration profile is modelled in several parts, all of which are associated together through a common ME ID. (The client PPTP xDSL UNI part 3 refers to the entire set of line configuration parts). + +#### *Attributes* + +**Managed entity ID**: This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**TPS-TC testmode (TPS\_TESTMODE)**: This Boolean attribute specifies whether the TPS-TC test mode defined in clause 8.3.1 [ITU-T G.9701] is enabled (true=1) or disabled (false=0). See clause 7.3.1 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**DRA testmode (DRA\_TESTMODE)**: This Boolean attribute defines whether the dynamic resource allocation (DRA) testmode defined in clause 9.8.3.1.2 of [ITU-T G.9701] is enabled (true=1) or disabled (false=0). See clause 7.3.2 of [ITU-T G.997.2] for detailed specification. (R, W) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.7.55 FAST vectoring line configuration extensions + +This ME extends FAST line configuration MEs with attributes that are specific to vectoring. An instance of this ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with a PPTP UNI part 3. + +The overall FAST line configuration MEs are modelled in several parts, all of which are associated together through a common ME ID (The client PPTP xDSL UNI part 3 refers to the entire set of line configuration parts). + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. All FAST line configuration profiles and extensions that pertain to a given PPTP xDSL UNI must share a common ME ID. (R, set-by-create) (mandatory) (2 bytes) + +**FEXT cancellation enabling/disabling upstream (FEXT\_TO\_CANCEL\_ENABLEus):** +A value of 1 enables and a value of 0 disables FEXT cancellation in the upstream direction from all the other vectored lines into the line in the vectored group. See clause 7.1.7.2 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +**FEXT cancellation enabling/disabling downstream (FEXT\_TO\_CANCEL\_ENABLEds):** +A value of 1 enables and a value of 0 disables FEXT cancellation in the downstream direction from all the other vectored lines into the line in the vectored group. See clause 7.1.7.1 of [ITU-T G.997.2]. (R, W) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.7.56 FAST line inventory and status data, part 1 + +This ME extends the FAST line inventory and status data MEs with attributes specific to [ITU-T G.997.2]. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a PPTP xDSL UNI part 1. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI part 1. It is required only if FAST is supported by the PPTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**ITU-T G.9701 profile (PROFILE):** This attribute reports for each profile whether operation according to that profile is enabled (0) or disabled (1). Only one profile can be enabled. See clause 7.10.1.1 of [ITU-T G.997.2] (R) (mandatory) (1 byte) + +**Upstream gamma data rate (GDRus):** This attribute reports the upstream net data rate as defined in clause 7.11.1.1, lowered by any throughput capability limitations remaining in the DRA or L2+ functions, assuming no user data are transmitted + +over all the other lines. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.11.1.3 of [ITU-T G.997.2] (R) (mandatory) (bytes) + +**Upstream attainable gamma data rate (ATTGDRus):** This attribute reports the attainable upstream net data rate (as defined in clause 7.11.2.1), lowered by any throughput capability limitations remaining in the DRA or L2+ functions, assuming no user data are transmitted over all the other Lines, and assuming MAXGDR (as defined in clause 7.2.1.3) is configured to its maximum valid value. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.11.2.3 of [ITU-T G.997.2] (R) (mandatory) (bytes) + +**DPU system vendor ID (DPU\_SYSTEM\_VENDOR):** This attribute reports the DPU system vendor ID as inserted by the FTU-O in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]) and as defined in clause 9.3.3.1 of [ITU-T G.994.1]. See clause 7.13.2.1 of [ITU-T G.997.2] (R) (optional) (8 bytes) + +**NT system vendor ID (NT\_SYSTEM\_VENDOR):** This attribute reports the NT system vendor ID as inserted by the FTU-R in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]) and as defined in clause 9.3.3.1 of [ITU-T G.994.1]. See clause 7.13.2.2 of [ITU-T G.997.2] (R) (optional) (8 bytes) + +**DPU serial number (DPU\_SYSTEM\_SERIALNR):** This attribute reports the DPU serial number as inserted by the FTU-O in the embedded operations channel. See clause 11.2.2.10 of [ITU-T G.9701]. It is vendor-specific information. The combination of DPU system vendor ID and DPU system serial number creates a unique number for each DPU. See clause 7.13.2.3 of [ITU-T G.997.2] (R) (optional) (32 bytes) + +**NT serial number (NT\_SYSTEM\_SERIALNR):** This attribute reports the NT system serial number as inserted by the FTU-R in the embedded operations channel. See clause 11.2.2.10 of [ITU-T G.9701]. It shall contain the NT system serial number, the NT model and the NT firmware version. All shall be encoded in this order and separated by space characters, i.e., "". The combination of NT system vendor ID and NT system serial number creates a unique number for each NT. See clause 7.13.2.4 of [ITU-T G.997.2] (R) (optional) (32 bytes) + +**Downstream gamma data rate (GDRds):** This attribute reports the downstream net data rate as defined in clause 7.11.1.1 of [ITU-T G.997.2], lowered by any throughput capability limitations remaining in the DRA or L2+ functions, assuming no user data are transmitted over all the other lines. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.11.1.3 of [ITU-T G.997.2] (R) (optional) (4 bytes) + +**Downstream attainable gamma data rate (ATTGDRds):** This attribute reports the attainable downstream net data rate (as defined in clause 7.11.2.1 of [ITU-T G.997.2]), lowered by any throughput capability limitations remaining in the DRA or L2+ functions, assuming no user data are transmitted over all the other Lines, and assuming MAXGDR (as defined in clause 7.2.1.3) is configured to its maximum valid value. Valid values range from 0 (0 kbit/s) to 4294967295 ( $2^{32}-1$ kbit/s). See clause 7.11.2.3 of [ITU-T G.997.2] (R) (optional) (4 bytes) + +**Downstream signal-to-noise ratio margin (SNRMds):** This attribute reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701]) and + +11.4.1.1.10 of [ITU-T G.9701]) in the downstream direction during the L0 link state. See clause 7.10.3.1 of [ITU-T G.997.2] for detailed specification. (R) (optional) (2 bytes). + +**Upstream signal-to-noise ratio margin (SNRMus):** This attribute reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the upstream direction during the L0 link state. See clause 7.10.3.2 of [ITU-T G.997.2] for detailed specification. (R) (optional) (2 bytes). + +**Downstream net data rate (NDRds):** This attribute reports the downstream NDR as defined in clause 11.4.1.1.1 of [ITU-T G.9701]. A special value 0xFFFFFFFF indicates that the NDR is undetermined. See clause 7.11.1.1 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**Upstream net data rate (NDRus):** This attribute reports the downstream NDR as defined in clause 11.4.1.1.1 of [ITU-T G.9701]. A special value of 0xFFFFFFFF ( $2^{32}-1$ ) indicates that the NDR is undetermined. See clause 7.11.1.1 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**Downstream attainable net data rate (ATTNDRds):** This attribute reports the downstream attainable NDR as defined in clause 11.4.1.1.2 of [ITU-T G.9701]. A special value 0xFFFFFFFF ( $2^{23}-1$ ) indicates that the attainable NDR is undetermined. The object is updated only in L0 link state. See clause 7.11.1.1 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**Upstream attainable net data rate (ATTNDRus):** This attribute reports the downstream attainable NDR as defined in clause 11.4.1.1.2 of [ITU-T G.9701]. A special value of 0xFFFFFFFF ( $2^{32}-1$ ) indicates that the attainable NDR is undetermined. The object is updated only in L0 link state. See clause 7.11.2.1 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### **9.7.57 FAST line inventory and status data part 2** + +This ME contains part 3 of the FAST line inventory and status data with attributes specific to [ITU-T G.997.2]. The ONU automatically creates or deletes an instance of this ME upon the creation or deletion of a PTP xDSL UNI part 1. + +#### *Relationships* + +This is one of the status data MEs associated with an xDSL UNI part 1. It is required only if FAST is supported by the PTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PTP xDSL UNI part 1. (R) (mandatory) (2 bytes) + +**Date/time-stamping of last successful downstream FRA operation (STAMP-FRAd):** This attribute reports the date/time of the last successful FTU-R initiated FRA execution that has modified the bits allocation. See clause 7.10.14.5 of + +[ITU-T G.997.2]. The format of this parameter is the same as STAMP-TEST-NE (see clause 9.7.37). (R) (optional) (7 bytes) + +- Date/time-stamping of last successful upstream FRA operation (STAMP-FRAus):** This parameter reports the date/time of the last successful FTU-O initiated FRA execution that has modified the bits allocation. See clause 7.10.14.6 of [ITU-T G.997.2]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) +- Date/time-stamping of last successful downstream RPA operation (STAMP-RPAds):** This parameter reports the date/time of the last successful FTU-R initiated RPA execution that has modified the bits allocation for the RMC. See clause 7.10.14.7 of [ITU-T G.997.2]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) +- Date/time-stamping of last successful upstream RPA operation (STAMP-RPAus):** This parameter reports the date/time of the last successful FTU-O initiated RPA execution that has modified the bits allocation for the RMC. See clause 7.10.14.8 of [ITU-T G.997.2]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) +- Date/time-stamping of last successful downstream TIGA operation (STAMP-TIGA):** This parameter reports the date/time of the last successful FTU-O initiated TIGA execution. See clause 7.10.14.9 of [ITU-T G.997.2]. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes) +- Date/time-stamping of last successful downstream bit swap operation (STAMP-BSWds):** This attribute reports the date/time of the last successful FTU-R initiated bit swap execution that has modified the bits allocation. See clause 7.10.14.1 of [ITU-T G.997.2] for detailed specification. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes). +- Date/time-stamping of last successful upstream bit swap operation (STAMP-BSWus):** This attribute reports the date/time of the last successful FTU-R initiated bit swap execution that has modified the bits allocation. See clause 7.10.14.1 of [ITU-T G.997.2] for detailed specification. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes). +- Date/time-stamping of last successful downstream autonomous SRA operation (STAMP-SRAds):** This attribute reports the date/time of the last successful FTU-R initiated autonomous SRA execution (excluding SRAs in response to TIGA) that has modified the bits allocation. See clause 7.10.14.3 of [ITU-T G.997.2] for detailed specification. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes). +- Date/time-stamping of last successful upstream autonomous SRA operation (STAMP-SRAus):** This attribute reports the date/time of the last successful FTU-R initiated autonomous SRA execution (excluding SRAs in response to TIGA) that has modified the bits allocation. See clause 7.10.14.3 of [ITU-T G.997.2] for detailed specification. The format of this parameter is the same as STAMP-TEST-NE. (R) (optional) (7 bytes). + +#### *Actions* + +Get + +#### *Notifications* + +None. + +### 9.7.58 FAST FTU-O performance monitoring history data + +This ME collects PM data on the FTU-R to FTU-O path as seen from the FTU-O for the previous or the current 15 minutes interval (depending on whether "get" or "get current data" command is used, as defined in clause I.4). Instances of this ME are created and deleted by the OLT. For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI part 1. It is required only if FAST is supported by the PPTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Successful FRA counter (CURR/PREV\_NE\_15\_FRA):** This attribute counts the successful upstream FRA primitives (success\_FRA). The successful FRA primitive (success\_FRA) is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.22 of [ITU-T G.997.2]. (R) (mandatory) (4 bytes) + +**Successful RPA counter (CURR/PREV\_NE\_15\_RPA):** This attribute counts the successful upstream RPA primitives (success\_RPA). The successful RPA primitive (success\_RPA) is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.23 of [ITU-T G.997.2] (R) (optional) (4 bytes) + +**Successful TIGA counter (CURR/PREV\_NE\_15\_TIGA):** This attribute counts the successful TIGA primitives (success\_TIGA). The successful TIGA primitive (success\_TIGA) is defined in clause 11.3.1.6 of [ITU-T G.9701]. Reported only with the near-end measured time, invalid data flag and timestamp. See clause 7.7.24 of [ITU-T G.997.2] (R) (optional) (4 bytes) + +**Successful bit swap counter (CURR/PREV\_NE\_15\_BSW):** This attribute reports a count of the successful upstream bit swap primitives (success\_BSW). The successful bit swap primitive is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.20 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**Successful autonomous SRA counter (CURR/PREV\_NE\_15\_SRA):** This attribute reports a count of the successful upstream autonomous SRA primitives (success\_SRA). The successful autonomous SRA primitive is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.21 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**ES counter (CURR/PREV\_NE\_15\_ES):** This attribute reports the count of Errored Seconds (ES) in the upstream. An ES is defined in clause 11.4.4.1 of [ITU-T G.9701]. See clause 7.7.8 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**SES counter (CURR/PREV\_NE\_15\_SES):** This attribute reports the count of Severely Errored Seconds (SES) in the upstream. An SES is defined in clause 11.4.4.2 + +of [ITU-T G.9701]. See clause 7.7.9 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +- LOS second (LOSS) counter (CURR/PREV\_NE\_15\_LOSS):** This attribute reports the count of LOS seconds (LOSS) in the upstream. A LOSS is defined in clause 11.4.4.3 of [ITU-T G.9701]. See clause 7.7.10 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). +- LOR second (LORS) counter(CURR/PREV\_NE\_15\_LORS):** This attribute reports the count of LOR seconds (LORS) in the upstream. A LORS is defined in clause 11.4.4.4 of [ITU-T G.9701]. See clause 7.7.11 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). +- UAS counter (CURR/PREV\_NE\_15\_UAS):** This attribute reports the count of unavailable seconds (UAS) in the upstream. An unavailable second is defined in clause 11.4.4.5 of [ITU-T G.9701]. See clause 7.7.12 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). +- Full inits counter (CURR/PREV\_15\_FULL\_INITS):** This attribute reports a count of full initialization primitives (full\_init). The full initialization primitive is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. See clause 7.7.13 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). +- Failed full inits counter (CURR/PREV\_15\_FAILEDFULL\_INITS):** This attribute reports a count of failed full initialization primitives (failedfull\_init). The failed full initialization primitive is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. See clause 7.7.14 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). +- Fast inits counter (CURR/PREV\_15\_FAST\_INITS):** This attribute reports a count of fast initialization primitives (fast\_init). The fast initialization primitive is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. See clause 7.7.15 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). +- Failed Fast inits counter (CURR/PREV\_15\_FAILEDFAST\_INITS):** This attribute reports a count of the failed fast initialization primitives (failedfast\_init). The failed fast initialization primitive is defined in clause 11.3.1.5 of [ITU-T G.9701]. It is reported only with the near-end PM counters. See clause 7.7.10 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +- None. + +### **9.7.59 FAST FTU-R performance monitoring history data** + +This ME collects PM data of the FTU-O to FTU-R path as seen from the FTU-R for the previous or the current 15 minutes interval (depending on whether "get" or "get current data" command is used, as defined in clause I.4). Instances of this ME are created and deleted by the OLT. For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an xDSL UNI part 1. It is required only if FAST is supported by the PTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PTP xDSL UNI part 1 that supports these attributes. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Successful FRA counter (CURR/PREV\_FE\_15\_FRA):** This attribute counts the successful downstream FRA primitives (success\_FRA). The successful FRA primitive (success\_FRA) is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.22 of [ITU-T G.997.2] (R) (mandatory) (4 bytes) + +**Successful RPA counter (CURR/PREV\_FE\_15\_RPA):** This attribute counts the successful downstream RPA primitives (success\_RPA). The successful RPA primitive (success\_RPA) is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.23 of [ITU-T G.997.2] (R) (optional) (4 bytes) + +**Successful bit swap counter (CURR/PREV\_FE\_15\_BSW):** This attribute reports a count of the successful downstream bit swap primitives (success\_BSW). The successful bit swap primitive is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.20 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**Successful autonomous SRA counter (CURR/PREV\_FE\_15\_SRA):** This attribute reports a count of the successful downstream autonomous SRA primitives (success\_SRA). The successful autonomous SRA primitive is defined in clause 11.3.1.6 of [ITU-T G.9701]. See clause 7.7.21 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**ES counter (CURR/PREV\_FE\_15\_ES):** This attribute reports the count of Errored Seconds (ES) in the downstream. An ES is defined in clause 11.4.4.1 of [ITU-T G.9701]. See clause 7.7.8 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**SES counter (CURR/PREV\_FE\_15\_SES):** This attribute reports the count of Severely Errored Seconds (SES) in the downstream. An SES is defined in clause 11.4.4.2 of [ITU-T G.9701]. See clause 7.7.9 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**LOS seconds (LOSS) counter (CURR/PREV\_FE\_15\_LOSS):** This attribute reports the count of LOS seconds (LOSS) in the downstream. A LOSS is defined in clause 11.4.4.3 of [ITU-T G.9701]. See clause 7.7.10 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**LOR seconds (LORS) counter (CURR/PREV\_FE\_15\_LORS):** This attribute reports the count of LOR seconds (LORS) in the downstream. A LORS is defined in clause 11.4.4.4 of [ITU-T G.9701]. See clause 7.7.11 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +**UAS counter (CURR/PREV\_FE\_15\_UAS):** This attribute reports the count of unavailable seconds (UAS) in the downstream. An unavailable second is defined in clause 11.4.4.5 of [ITU-T G.9701]. See clause 7.7.12 of [ITU-T G.997.2] for detailed specification. (R) (optional) (4 bytes). + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +None + +### 9.7.60 FAST line failures performance monitoring data + +This ME collects data on the line failures of the FTU-O and the FTU-R for the previous or the current 15 minutes interval (depending on whether "get" or "get current data" command is used, as defined in clause I.4). Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with an xDSL UNI part 1. It is required only if FAST is supported by the PPTP. The ONU automatically creates or deletes an instance of this ME upon creation or deletion of a PPTP xDSL UNI part 1 that supports these attributes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a PPTP xDSL UNI part 1. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Near-end LOS failure counter (CURR/PREV\_NE\_15\_LOS):** This attribute reports the count of LOS failures at the XTU-C, as defined in clause 7.4.1.1 of [ITU-T G.997.2]. See clause 7.7.4 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Near-end LOR failure counter (CURR/PREV\_NE\_15\_LOR):** This attribute reports the count of LOR failures at the XTU-C, as defined in clause 7.4.1.2 of [ITU-T G.997.2]. See clause 7.7.5 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Near-end LOM failure counter (CURR/PREV\_NE\_15\_LOM):** This attribute reports the count of LOM failures at the XTU-C, as defined in clause 7.4.1.3 of [ITU-T G.997.2]. See clause 7.7.6 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Near-end LPR failure counter (CURR/PREV\_NE\_15\_LPR):** This attribute reports the count of LPR failures at the XTU-C, as defined in clause 7.4.1.4 of [ITU-T G.997.2]. See clause 7.7.7 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Far-end LOS failure counter (CURR/PREV\_FE\_15\_LOS):** This attribute reports the count of LOS failures at the XTU-C, as defined in clause 7.4.2.1 of + +[ITU-T G.997.2]. See clause 7.7.4 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Far-end LOR failure counter (CURR/PREV\_FE\_15\_LOR):** This attribute reports the count of LOR failures at the XTU-C, as defined in clause 7.4.2.2 of [ITU-T G.997.2]. See clause 7.7.5 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Far-end LOM failure counter (CURR/PREV\_FE\_15\_LOM):** This attribute reports the count of LOM failures at the XTU-C, as defined in clause 7.4.2.3 of [ITU-T G.997.2]. See clause 7.7.6 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +**Far-end LPR failure counter (CURR/PREV\_FE\_15\_LPR):** This attribute reports the count of LPR failures at the XTU-C, as defined in clause 7.4.2.4 of [ITU-T G.997.2]. See clause 7.7.7 of [ITU-T G.997.2] for detailed specification. (R) (mandatory) (4 bytes). + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +None + +## **9.8 Time division multiplex services** + +This clause defines MEs associated with CES UNIs, as shown in Figure 9.8-1. + +![Diagram of managed entities associated with TDM services. The diagram shows various entities like 9.8.3: CES service profile, 9.8.1: PTP CES UNI, 9.8.2: Logical N x 64 sub-port CTP, 9.8.5: Pseudowire termination point, 9.8.9: Ethernet flow TP, 9.8.15: PW ATM config data, 9.8.16: PW ATM PM history data, 9.8.4: CES physical interface PM history data, 9.8.12: ... part 2, 9.8.13: ... part 3, 9.8.6: RTP pseudowire parameters, 9.8.8: Pseudowire PM history data, 9.8.7: Pseudowire maintenance profile, 9.8.14: MPLS PW TP, 9.8.17: PW Ethernet config data. Relationships are shown with arrows labeled 'Pointed to by:' or 'Points to:' with specific data types.](1e63e086b5935f69f765b06133f2d8f6_img.jpg) + +The diagram illustrates the managed entities associated with TDM services and their relationships: + +- 9.8.3: CES service profile** is pointed to by **GEM interworking TP** (N). +- 9.8.1: PTP CES UNI** is pointed to by **GEM interworking TP** and is associated with **9.8.4: CES physical interface PM history data**, **9.8.12: ... part 2**, and **9.8.13: ... part 3**. +- 9.8.2: Logical $N \times 64$ sub-port CTP** is pointed to by **GEM interworking TP** and points to **9.8.1: PTP CES UNI**. +- 9.8.5: Pseudowire termination point** points to **9.8.1: PTP CES UNI** and **9.8.9: Ethernet flow TP**. It is associated with **9.8.6: RTP pseudowire parameters**, **9.8.8: Pseudowire PM history data**, and **9.8.7: Pseudowire maintenance profile**. It also points to **TCP/UDP config data** and **Large string (FE TP URI)**. +- 9.8.9: Ethernet flow TP** is pointed to by **802.1p mapper service profile**, **MAC bridge port config data**, **(Extended) VLAN tagging operation config data**, and **9.8.15: PW ATM config data**. It points to **GEM interworking TP** (N) and **9.8.14: MPLS PW TP**. +- 9.8.15: PW ATM config data** points to **TCP/UDP config data** and **PTP ATM UNI**, and is associated with **9.8.16: PW ATM PM history data**. +- 9.8.14: MPLS PW TP** points to **9.8.17: PW Ethernet config data**. +- 9.8.17: PW Ethernet config data** points to **PTP UNI**, **802.1p mapper**, and **VEIP**. + +G.988(17)\_F9.8-1 + +Diagram of managed entities associated with TDM services. The diagram shows various entities like 9.8.3: CES service profile, 9.8.1: PTP CES UNI, 9.8.2: Logical N x 64 sub-port CTP, 9.8.5: Pseudowire termination point, 9.8.9: Ethernet flow TP, 9.8.15: PW ATM config data, 9.8.16: PW ATM PM history data, 9.8.4: CES physical interface PM history data, 9.8.12: ... part 2, 9.8.13: ... part 3, 9.8.6: RTP pseudowire parameters, 9.8.8: Pseudowire PM history data, 9.8.7: Pseudowire maintenance profile, 9.8.14: MPLS PW TP, 9.8.17: PW Ethernet config data. Relationships are shown with arrows labeled 'Pointed to by:' or 'Points to:' with specific data types. + +**Figure 9.8-1 – Managed entities associated with TDM services** + +### 9.8.1 Physical path termination point CES UNI + +This ME represents the point at a CES UNI in the ONU where the physical path terminates and physical level functions are performed. + +The ONU automatically creates an instance of this ME per port: + +- when the ONU has CES ports built into its factory configuration; +- when a cardholder is provisioned to expect a circuit pack of a CES type; +- when a cardholder provisioned for plug-and-play is equipped with a circuit pack of a CES type. Note that the installation of a plug-and-play card may indicate the presence of CES ports via equipment ID as well as its type and indeed may cause the ONU to instantiate a port-mapping package that specifies CES ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a CES circuit pack, nor is it equipped with a CES circuit pack. + +#### Relationships + +An instance of this ME is associated with each real or pre-provisioned CES port. It can be linked from a GEM IW TP, a pseudowire TP or a logical $N \times 64$ kbit/s CTP. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +**Expected type:** The following coding is used for this attribute- + +- 0 Autosense +- 1 to 254 One of the values from Table 9.1.5-1 that is compatible with a CES circuit pack + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +**Sensed type:** If the value of expected type is not 0, then the value of sensed type equals the value of expected type. If expected type = 0, then the value of sensed type is one of the compatible values from Table 9.1.5-1. Upon ME instantiation, the ONU sets this attribute to 0 or to the value that reflects the physically present equipment. (R) (mandatory if the ONU supports circuit packs with configurable interface types, e.g., C1.5/2/6.3) (1 byte) + +**CES loopback configuration:** This attribute specifies and reports the loopback configuration of the physical interface. + +- 0 No loopback +- 1 Payload loopback +- 2 Line loopback +- 3 Operations system-directed (OS-directed) loopback 1 (loopback from/to PON side) +- 4 OS-directed loopback 2 (loopback from/to CES UNI side) +- 5 OS-directed loopback 3 (loopback of both PON side and CES UNI side) +- 6 Manual button-directed loopback [read only (RO)] +- 7 Network-side code inband-directed loopback (RO) +- 8 SmartJack-directed loopback (RO) +- 9 Network-side code inband-directed loopback (armed; RO) +- 10 Remote-line loopback via facility data link (FDL) +- 11 Remote-line loopback via inband code +- 12 Remote-payload loopback + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory) (1 byte) + +![Diagram of CES loopback configuration showing an ONU with a PHY framer and a PON interface. The diagram illustrates three loopback paths: Loopback 1 (from PON interface to PHY framer), Loopback 2 (from PHY framer to PON interface), and Loopback 3 (from the output of the PON interface back to its input). The CES UNI is connected to the PHY framer, and the PON is connected to the PON interface.](55967a38db51ac74576bcb353d4e71a4_img.jpg) + +The diagram shows an ONU (Optical Network Unit) containing two main components: a 'PHY framer' and a 'PON interface'. The 'CES UNI' (Circuit Emulation User Network Interface) is connected to the left side of the PHY framer. The PON interface is connected to the right side of the PHY framer and has an external connection to a 'PON' (Passive Optical Network) represented by a circle with three lines. Three loopback paths are indicated with arrows: 'Loopback 1' is a curved arrow from the output of the PON interface back to its input; 'Loopback 2' is a curved arrow from the output of the PHY framer back to its input; 'Loopback 3' is a long curved arrow from the output of the PON interface back to the input of the PHY framer. A label 'G.988(12)\_F9.8.1-1' is located at the bottom right of the diagram. + +Diagram of CES loopback configuration showing an ONU with a PHY framer and a PON interface. The diagram illustrates three loopback paths: Loopback 1 (from PON interface to PHY framer), Loopback 2 (from PHY framer to PON interface), and Loopback 3 (from the output of the PON interface back to its input). The CES UNI is connected to the PHY framer, and the PON is connected to the PON interface. + +**Figure 9.8.1-1 – CES loopback configuration** + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Framing:** This attribute specifies the framing structure. + +These code points are for use with DS1 services. Code point 2 may also be used for an unframed E1 service. + +- 0 Extended superframe +- 1 Superframe +- 2 Unframed +- 3 ITU-T G.704 + +NOTE – [ITU-T G.704] describes both SF and ESF framing for DS1 signals. This code point is retained for backward compatibility, but its meaning is undefined. + +- 4 JT-G.704 + +The following code points are for use with E1 services. + +- 5 Basic framing: clause 2.3.2 of [ITU-T G.704] +- 6 Basic framing with CRC-4: clause 2.3.3 of [ITU-T G.704] +- 7 Basic framing with TS16 multiframe +- 8 Basic framing with CRC-4 and TS16 multiframe + +Upon ME instantiation, the ONU sets this attribute to a value that reflects the vendor's default. (R, W) (optional) (1 byte) + +**Encoding:** This attribute specifies the line coding scheme. Valid values are as follows. + +- 0 B8ZS +- 1 AMI +- 2 HDB3 +- 3 B3ZS + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (mandatory for DS1 and DS3 interfaces) (1 byte) + +**Line length:** This attribute specifies the length of the twisted pair cable from a DS1 physical UNI to the DSX-1 cross-connect point or the length of coaxial cable from a DS3 physical UNI to the DSX-3 cross-connect point. Valid values are given in Table 9.8.1-1. Upon ME instantiation for a DS1 interface, the ONU assigns the value 0 for non-power feed type DS1 and the value 6 for power feed type DS1. Upon ME instantiation for a DS3 interface, the ONU sets this attribute to 0x0F. (R, W) (optional) (1 byte) + +**DS1 mode:** This attribute specifies the mode of a DS1. Valid values are as follows. + +| Value | Mode | Connect | Line length | Power | Loopback | +|-------|------|-------------|-------------|-----------------|-----------------------------------------------------| +| 0 | No.1 | DS1 CPE | Short haul | No power feed | Smart jack | +| 1 | No.2 | DS1 CPE | Long haul | No power feed | Smart jack | +| 2 | No.3 | DS1 NIU CPE | Long haul | No power feed | Intelligent office repeater.
Transparent to FDL. | +| 3 | No.4 | DS1 NIU CPE | Long haul | With power feed | Intelligent office repeater.
Transparent to FDL. | + +In the event of conflicting values between this attribute and the (also optional) line length attribute, the line length attribute is taken to be valid. This permits the separation of line build-out (LBO) and power settings from smart jack and + +FDL behaviour. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Line type:** This attribute specifies the line type used in a DS3 or E3 application or when the sensed type of the PPTP is configurable. Valid values are as follows. + +- 0 Other +- 1 ds3 m23 +- 2 ds3 syntran +- 3 ds3 Cbit parity +- 4 ds3 clear channel +- 5 e3 framed +- 6 e3 plcp +- 7 DS1 +- 8 E1 +- 9 J1 + +(R, W) (mandatory for DS3, E3 and multi-configuration interfaces, not applicable to other interfaces) (1 byte) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-----------------------------------------------------| +| 1 | N/A | | +| 2 | Sensed type | Sensed circuit pack type (value from Table 9.1.5-1) | +| 3 | CES loopback config | Loopback configuration of physical interface | +| 4 | N/A | | +| 5 | Op state | Operational state | +| 6..9 | N/A | | +| 10 | ARC | ARC timer expiration | +| 11..12 | N/A | | +| 13..16 | Reserved | | + +Alarms should be declared and cleared according to criteria defined separately in existing TDM standards. + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------|-------------------------------------------| +| 0 | TF | Transmitter failure | +| 1 | LOS | Loss of signal | +| 2 | LOF | Loss of frame | +| 3 | OOF | Out of frame | +| 4 | RAI | Remote alarm indication | +| 5 | 1.5 M BAIS | 1.544 Mbit/s back alarm indication signal | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|----------------------------------------| +| 6 | R-INH | Receive alarm inhibit | +| 7 | 6M REC | 6.312 Mbit/s receive alarm | +| 8 | 6M SEND | 6.312 Mbit/s send alarm | +| 9 | 6M ERR | 6.312 Mbit/s block error | +| 10 | 6M BERR | 6.312 Mbit/s back error | +| 11 | 34M REC | 34.368 Mbit/s receive alarm | +| 12 | 34M AIS | 34.368 Mbit/s alarm indication signal | +| 13 | 2M REC | 2.048 Mbit/s receive alarm | +| 14 | 2M AIS | 2.048 Mbit/s alarm indication signal | +| 15 | 1.5M REC | 1.544 Mbit/s receive alarm | +| 16 | 1.5 AIS | 1.544 Mbit/s alarm indication signal | +| 17 | INFO0 | INFO0 reception (INFO0) | +| 18 | 45M RDI | 44.736 Mbit/s remote defect indication | +| 19 | 45M AIS | 44.736 Mbit/s alarm indication signal | +| 20 | AIS-CI | Refer to [b-ATIS-0300231] | +| 21 | DS1 idle | Refer to [b-ATIS-0600403] | +| 22 | RAI-CI | Refer to [b-ATIS-0300231] | +| 23..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +**Table 9.8.1-1– Values for the line length attribute** + +| Value | Power feed | Line length | +|-------|------------------------------------------|------------------------------| +| 0x00 | Non-power feed type DS1 | 0..33.5 m (0..110 ft) | +| 0x01 | Non-power feed type DS1 | 33.5..67.1 m (110..220 ft) | +| 0x02 | Non-power feed type DS1 | 67.1..100.6 m (220..330 ft) | +| 0x03 | Non-power feed type DS1 | 100.6..134.1 m (330..440 ft) | +| 0x04 | Non-power feed type DS1 | 134.1..167.6 m (440..550 ft) | +| 0x05 | Non-power feed type DS1 | 167.6..201.2 m (550..660 ft) | +| 0x06 | Power feed type DS1 (Wet T1), short haul | 0..40.5 m (0..133 ft) | +| 0x07 | Power feed type DS1 (Wet T1), short haul | 40.5..81.1 m (133..266 ft) | +| 0x08 | Power feed type DS1 (Wet T1), short haul | 81.1..121.6 m (266..399 ft) | +| 0x09 | Power feed type DS1 (Wet T1), short haul | 121.6..162.5 m (399..533 ft) | +| 0x0A | Power feed type DS1 (Wet T1), short haul | 162.5..199.6 m (533..655 ft) | +| 0x0B | Power feed type DS1 (Wet T1), long haul | 0 dB | +| 0x0C | Power feed type DS1 (Wet T1), long haul | 7.5 dB | +| 0x0D | Power feed type DS1 (Wet T1), long haul | 15 dB | +| 0x0E | Power feed type DS1 (Wet T1), long haul | 22.5 dB | + +**Table 9.8.1-1– Values for the line length attribute** + +| Value | Power feed | Line length | +|-------|----------------|-----------------------------| +| 0x0F | DS3 power feed | 0..68.6 m (0..225 ft) | +| 0x10 | DS3 power feed | 68.6..137.2 m (225..450 ft) | + +### 9.8.2 Logical $N \times 64$ kbit/s sub-port connection termination point + +This ME models a logical sub-port contained within a higher level TDM physical layer interface (e.g., a group of DS0s within a DS1, a DS1 within a DS3, etc.). An instance of this ME can represent an arbitrary (i.e., consecutive or non-consecutive) group of multiple channels/time slots (e.g., multiple DS0/DS1) as an integral bundle. + +#### Relationships + +Zero or more instances of this ME are associated with an instance of the PPTP CES UNI. It can be linked from a pseudowire TP. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Physical path termination pointer:** This attribute points to the corresponding PPTP CES UNI ME instance. (R, W, set-by-create) (mandatory) (2 bytes) + +**List of time slots:** This attribute is a bit map that indicates time slots or component tributaries. Each bit indicates whether the corresponding time slot is included in the connection (1) or not (0). Figure 9.8.2-1 shows the correspondence. (R, W, set-by-create) (mandatory) (12 bytes) + +| Byte | Bit | | | | | | | | +|------|---------|-------|-------|-------|-------|-------|-------|-------| +| | 8 (MSB) | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| 1 | TS 0 | TS 1 | TS 2 | TS 3 | TS 4 | TS 5 | TS 6 | TS 7 | +| 2 | TS 8 | TS 9 | TS 10 | TS 11 | TS 12 | TS 13 | TS 14 | TS 15 | +| ... | | | | | | | | | +| 12 | TS 88 | TS 89 | TS 90 | TS 91 | TS 92 | TS 93 | TS 94 | TS 95 | + +**Figure 9.8.2-1 – Mapping of time slots** + +#### Actions + +Create, delete, get, set + +#### Notifications + +None. + +### 9.8.3 CES service profile + +NOTE – In [ITU-T G.984.4], this ME is called a CES service profile-G. + +An instance of this ME organizes data that describe the CES service functions of the ONU. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of a GEM IW TP. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**CES buffered CDV tolerance:** This attribute represents the duration of user data that must be buffered by the CES IW entity to offset packet delay variation. It is expressed in 10 µs increments. 75 (750 µs) is suggested as a default value. (R, W, set-by-create) (mandatory) (2 bytes) + +**Channel associated signalling (CAS):** This attribute selects the signalling format. It applies to structured interfaces only. For unstructured interfaces, this value, if present, must be set to the default 0. Valid values are as follows. + +- 0 Basic +- 1 E1 CAS +- 2 SF CAS +- 3 DS1 ESF CAS +- 4 J2 CAS + +(R, W, set-by-create) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.8.4 CES physical interface performance monitoring history data** + +This ME collects statistics for a CES physical interface. Interfaces include DS1, E1, J1, J2 and possibly others. The performance management requirements of particular interfaces are described in the corresponding ITU-T or other standards document, e.g., [ITU-T G.784] or [b-ATIS-0300231]. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with one instance of the PPTP CES UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP CES UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no mandatory threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Errored seconds:** When a detailed distinction needs to be made, this attribute corresponds to near-end line errored seconds, ES-L, also known as LES. (R) (mandatory) (2 bytes) + +**Severely errored seconds:** When a detailed distinction needs to be made, this attribute corresponds to near-end line severely errored seconds, SES-L. (R) (mandatory) (2 bytes) + +**Burst errored seconds:** A burst errored second (BES) is any second that is not an unavailable second (UAS), that contains between 2 and 319 error events but no LOS, AIS or OOF condition. This attribute is also known as ESB-P. (R) (optional) (2 bytes) + +**Unavailable seconds:** When a detailed distinction needs to be made, this attribute corresponds to near-end path unavailable seconds, UAS-P. (R) (mandatory) (2 bytes) + +**Controlled slip seconds:** When a detailed distinction needs to be made, this attribute corresponds to near-end path controlled slip seconds CSS-P. (R) (mandatory) (2 bytes) + +Each of the following attributes is (R) (optional) (2 bytes) + +| Attribute name | Common acronym | +|----------------------------------------|----------------| +| Loss of signal seconds | LOSS-L | +| AIS seconds | AISS-P | +| Errored seconds, path | ES-P | +| Errored seconds, type A | ESA-P | +| Severely errored seconds, path | SES-P | +| Severely errored frame and AIS seconds | SAS-P aka SEFS | +| Code violations, line | CV-L aka LCV | +| Code violations, path | CV-P aka PCV | +| Errored blocks (see [ITU-T G.826]) | EB | + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | ES | 1 | +| 1 | SES | 2 | +| 2 | BES | 3 | +| 3 | UAS | 4 | +| 4 | CSS | 5 | +| 5 | LOSS-L | 6 | +| 6 | AISS-P | 7 | +| 7 | ES-P | 8 | + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 8 | ESA-P | 9 | +| 9 | SES-P | 10 | +| 10 | SAS-P | 11 | +| 11 | CV-L | 12 | +| 12 | CV-P | 13 | +| 13 | EB | 14 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.8.5 Pseudowire termination point + +The pseudowire TP supports packetized (rather than TDM) transport of TDM services, transported either directly over Ethernet, over UDP/IP or over MPLS. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +One pseudowire TP ME exists for each distinct TDM service that is mapped to a pseudowire. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +##### **Underlying transport:** + +- 0 Ethernet, MEF 8 +- 1 UDP/IP +- 2 MPLS + +(R, W, set-by-create) (mandatory) (1 byte) + +**Service type:** This attribute specifies the basic service type, either a transparent bit pipe or an encapsulation that recognizes the underlying structure of the payload. + +- 0 Basic unstructured (also known as structure agnostic) +- 1 Octet-aligned unstructured, structure agnostic. Applicable only to DS1, a mode in which each frame of 193 bits is encapsulated in 25 bytes with 7 padding bits. +- 2 Structured (structure-locked) + +(R, W, set-by-create) (mandatory) (1 byte) + +##### **Signalling:** + +- 0 No signalling visible at this layer +- 1 CAS, to be carried in the same packet stream as the payload +- 2 CAS, to be carried in a separate signalling channel + +(R, W, set-by-create) (mandatory for structured service type) (1 byte) + +**TDM UNI pointer:** If service type = structured, this attribute points to a logical $N \times 64$ kbit/s sub-port CTP. Otherwise, this attribute points to a PTPP CES UNI. (R, W, set-by-create) (mandatory) (2 bytes) + +**North-side pointer:** When the pseudowire service is transported via IP, as indicated by the underlying transport attribute, the north-side pointer attribute points to an instance of the TCP/UDP config data ME. When the pseudowire service is + +transported directly over Ethernet, the north-side pointer attribute is not used – the linkage to the Ethernet flow TP is implicit in the ME IDs. When the pseudowire service is transported over MPLS, the north-side pointer attribute points to an instance of the MPLS PW TP. (R, W, set-by-create) (mandatory) (2 bytes) + +**Far-end IP info:** When the pseudowire service is transported via IP, this attribute points to a large string ME that contains the URI of the far-end TP, e.g., + +udp://192.168.100.221:5000 + +udp://pwe3srvr.int.example.net:2222 + +A null pointer is appropriate if the pseudowire is not transported via IP. (R, W, set-by-create) (mandatory for IP transport) (2 bytes) + +**Payload size:** Number of payload bytes per packet. Valid only if service type = basic unstructured or octet-aligned unstructured. Valid choices depend on the TDM service, but must include the following. Other choices are at the vendor's discretion. + +DS1 192 + +DS1 200, required only if an octet-aligned unstructured service is supported + +E1 256 + +DS3 1024 + +E3 1024 + +(R, W, set-by-create) (mandatory for unstructured service) (2 bytes) + +**Payload encapsulation delay:** Number of 125 µs frames to be encapsulated in each pseudowire packet. Valid only if service type = structured. The minimum set of choices for various TDM services is listed in the following table, and is affected by the possible presence of in-band signalling. Other choices are at the vendor's discretion. + +| Payload encapsulation delay | Payload type | +|------------------------------------------|--------------------------------| +| 64 required (8 ms),
40 desired (5 ms) | NxDS0, no signalling, N = 1 | +| 32 (4 ms) | NxDS0, no signalling, N = 2..4 | +| 8 (1 ms) | NxDS0, no signalling, N > 4 | +| 24 (3 ms) | NxDS0 with DS1 CAS | +| 16 (2 ms) | NxDS0 with E1 CAS | + +(R, W, set-by-create) (mandatory for structured service) (1 byte) + +**Timing mode:** This attribute selects the timing mode of the TDM service. If RTP is used, this attribute must be set to be consistent with the value of the RTP timestamp mode attribute in the RTP pseudowire parameters ME, or its equivalent, at the far end. + +0 Network timing (default) + +1 Differential timing + +2 Adaptive timing + +3 Loop timing: local TDM transmit clock derived from local TDM receive stream + +(R, W) (mandatory) (1 byte) + +**Transmit circuit ID:** This attribute is a pair of emulated circuit ID (ECID) values that the ONU transmits in the direction from the TDM termination towards the packet-switched network (PSN). MEF 8 ECIDs lie in the range 1..1048575 ( $2^{20} - 1$ ). To allow for the possibility of other transport (L2TP) in the future, each ECID is allocated 4 bytes. + +The first value is used for the payload ECID; the second is used for the optional separate signalling ECID. The first ECID is required for all MEF 8 pseudowires; the second is required only if signalling is to be carried in a distinct channel. If signalling is not present, or is carried in the same channel as the payload, the second ECID should be set to 0. + +(R, W) (mandatory for MEF 8 transport) (8 bytes) + +**Expected circuit ID:** This attribute is a pair of ECID values that the ONU can expect in the direction from the PSN towards the TDM termination. Checking ECIDs may be a way to detect circuit misconnection. MEF 8 ECIDs lie in the range 1..1048575 ( $2^{20} - 1$ ). To allow for the possibility of other transport (L2TP) in the future, each ECID is allocated 4 bytes. + +The first value is used for the payload ECID; the second is used for the optional separate signalling ECID. In both cases, the default value 0 indicates that no ECID checking is expected. + +(R, W) (optional for MEF 8 transport) (8 bytes) + +**Received circuit ID:** This attribute indicates the actual ECID(s) received on the payload and signalling channels, respectively. It may be used for diagnostic purposes. (R) (optional for MEF 8 transport) (8 bytes) + +**Exception policy:** This attribute points to an instance of the pseudowire maintenance profile ME. If the pointer has its default value 0, the ONU's internal defaults apply. (R, W) (optional) (2 bytes) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------------| +| 1..13 | N/A | | +| 14 | ARC | Alarm-reporting control cancellation | +| 15 | N/A | | +| 16 | Reserved | | + +Alarm criteria may be customized through reference to a pseudowire maintenance profile managed object, or defined by the ONU's internal defaults. + +##### Alarm + +| Alarm number | Event | Description | +|--------------|-------------------------|----------------------------------------------------------------------------------------------------------------| +| 0 | Misconnection | Excessive ratio of stray packets received from the PSN. | +| 1 | Loss of packets | Excessive ratio of lost packets from the PSN. | +| 2 | Buffer overrun | Excessive ratio of packets lost because they arrived from the PSN too early to be buffered for playout. | +| 3 | Buffer underrun | Excessive ratio of packets lost because they arrived from the PSN too late to be buffered for playout. | +| 4 | Malformed packets alarm | Excessive ratio of packets lost because their structure or payload type did not match the provisioned service. | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.8.6 RTP pseudowire parameters + +If a pseudowire service uses RTP, the RTP pseudowire parameters ME provides configuration information for the RTP layer. Instances of this ME are created and deleted by the OLT. The use of RTP on a pseudowire is optional, and is determined by the existence of the RTP pseudowire parameters ME. + +#### Relationships + +An instance of the RTP pseudowire parameters ME may exist for each pseudowire TP ME, to which it is implicitly bound by a common ME ID. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the pseudowire TP ME. (R, set-by-create) (mandatory) (2 bytes) + +**Clock reference:** This attribute specifies the frequency of the common timing reference, in multiples of 8 kHz. (R, W, set-by-create) (mandatory) (2 bytes) + +**RTP timestamp mode:** This attribute determines the mode in which RTP timestamps are generated in the TDM to the PSN direction. + +- 0 Unknown or not applicable. +- 1 Absolute. Timestamps are based on the timing of the incoming TDM signal. +- 2 Differential. Timestamps are based on the ONU's reference clock, which is understood to be stratum-traceable along with the reference clock at the far end. + +(R, W, set-by-create) (mandatory) (1 byte) + +**PTYPE:** This attribute specifies the RTP payload type in the TDM to the PSN direction. It comprises two 1 byte values. The first is for the payload channel, the second, for the optional separate signalling channel. Assignable PTYPES lie in the dynamic range 96..127. If signalling is not transported in its own channel, the second value should be set to 0. (R, W, set-by-create) (mandatory) (2 bytes) + +**SSRC:** This attribute specifies the RTP synchronization source in the TDM to the PSN direction. It comprises two 4 byte values. The first is for the payload channel, the second, for the optional separate signalling channel. If signalling is not transported in its own channel, the second value should be set to 0. (R, W, set-by-create) (mandatory) (8 bytes) + +**Expected PTYPE:** This attribute specifies the RTP payload type in the PSN to the TDM direction. The received payload type may be used to detect malformed packets. It comprises two 1 byte values. The first is for the payload channel, the second, for the optional separate signalling channel. To disable either or both of the check functions, set the corresponding value to its default value 0. (R, W, set-by-create) (optional) (2 bytes) + +**Expected SSRC:** This attribute specifies the RTP synchronization source in the PSN to the TDM direction. The received SSRC may be used to detect misconnection (stray packets). It comprises two 4 byte values. The first is for the payload channel, the second, for the optional separate signalling channel. To disable either or both of the check functions, set the corresponding value to its default value 0. (R, W, set-by-create) (optional) (8 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.8.7 Pseudowire maintenance profile** + +The pseudowire maintenance profile permits the configuration of pseudowire service exception handling. It is created and deleted by the OLT. + +The settings, and indeed existence, of a pseudowire maintenance profile affect the behaviour of the pseudowire PM history data ME only in establishing criteria for counting SESs, but in no other way. The pseudowire maintenance profile primarily affects the alarms declared by the subscribing pseudowire TP. + +#### *Relationships* + +One or more instances of the pseudowire TP may point to an instance of the pseudowire maintenance profile. If the pseudowire TP does not refer to a pseudowire maintenance profile, the ONU's default exception handling is implied. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0 is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Jitter buffer maximum depth:** This attribute specifies the desired maximum depth of the playout buffer in the PSN to the TDM direction. The value is expressed as a multiple of the 125 µs frame rate. The default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (2 bytes) + +**Jitter buffer desired depth:** This attribute specifies the desired nominal fill depth of the playout buffer in the PSN to the TDM direction. The value is expressed as a multiple of the 125 µs frame rate. The default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (2 bytes) + +**Fill policy:** This attribute defines the payload bit pattern to be applied towards the TDM service if no payload packet is available to play out. The default value 0 specifies that the ONU apply its internal policy. + +- 0 ONU default, vendor-specific (recommended: AIS for unstructured service, all 1s for structured service) +- 1 Play out AIS according to the service definition (for example, DS3 AIS) +- 2 Play out all 1s +- 3 Play out all 0s +- 4 Repeat the previous data +- 5 Play out DS1 idle (Appendix C of [b-ATIS-0600403]) +- 6..15 Reserved for future standardization +- 16..255 Vendor-specific, not to be standardized + +(R, W, set-by-create) (optional) (1 byte) + +Four pairs of alarm-related policy attributes, defined in the following, share common behaviour. + +The alarm declaration policy attribute defines the anomaly rate that causes the corresponding alarm to be declared. It is an integer percentage between 1..100. If this density of anomalies occurs during the alarm onset soak interval, the alarm is declared. The default value 0 selects the ONU's internal policy. + +The alarm clear policy attribute defines the anomaly rate that causes the corresponding alarm to be cleared. It is an integer percentage between 0..99. If no more than this density of anomalies occurs during the alarm clear soak interval, the alarm is cleared. The default value 255 selects the ONU's internal policy. + +**Misconnected packets declaration policy:** (R, W, set-by-create) (optional) (1 byte) + +**Misconnected packets clear policy:** (R, W, set-by-create) (optional) (1 byte) + +**Loss of packets declaration policy:** (R, W, set-by-create) (optional) (1 byte) + +**Loss of packets clear policy:** (R, W, set-by-create) (optional) (1 byte) + +**Buffer overrun/underrun declaration policy:** (R, W, set-by-create) (optional) (1 byte) + +**Buffer overrun/underrun clear policy:** (R, W, set-by-create) (optional) (1 byte) + +**Malformed packets declaration policy:** (R, W, set-by-create) (optional) (1 byte) + +**Malformed packets clear policy:** (R, W, set-by-create) (optional) (1 byte) + +**R-bit transmit set policy:** This attribute defines the number of consecutive lost packets that causes the transmitted R bit to be set in the TDM to the PSN direction, indicating lost packets to the far end. The default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (1 byte) + +**R-bit transmit clear policy:** This attribute defines the number of consecutive valid packets that causes the transmitted R bit to be cleared in the TDM to the PSN direction, removing the remote failure indication to the far end. The default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (1 byte) + +**R-bit receive policy:** This attribute defines the action towards the $N \times 64$ TDM interface when remote failure is indicated on packets received from the PSN (either R-bit set or $M = 0b10$ while the L bit is cleared). + +- 0 Do nothing (recommended to be the default) +- 1 Play out service-specific RAI/REI/RDI code +- 2 Send channel idle signalling and idle channel payload to all DS0s comprising the service + +(R, W, set-by-create) (optional) (1 byte) + +**L bit receive policy:** This attribute defines the action towards the TDM interface when far-end TDM failure is indicated on packets received from the PSN (L bit set). + +- 0 Play out service-specific AIS (recommended to be the default) +- 1 Repeat last received packet +- 2 Send channel idle signalling and idle channel payload to all DS0s comprising the service + +(R, W, set-by-create) (optional) (1 byte) + +**SES threshold:** Number of lost, malformed or otherwise unusable packets expected in the PSN to the TDM direction within a 1 s interval that causes an SES to be counted. Stray packets do not count towards an SES, nor do packets whose L bit is set at the far end. The value 0 specifies that the ONU uses its internal default, which is not necessarily the same as the recommended default value 3. (R, W, set-by-create) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.8.8 Pseudowire performance monitoring history data** + +This ME collects PM for a pseudowire TP. Most of the attributes monitor packets received from the PSN, and may therefore be considered egress PM. For the most part, ingress PM is collected at the CES PTP ME. + +NOTE – The pseudowire PM history data ME collects data similar, but not identical, to that available from the MAC bridge port PM history data ME associated with a MAC bridge. When the pseudowire is bridge-based, it may not be necessary to collect both. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the pseudowire TP. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the pseudowire TP. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +- Received packets:** This attribute counts the total number of packets, both payload and signalling, received in the PSN to the TDM direction. (R) (mandatory) (4 bytes) +- Transmitted packets:** This attribute counts the total number of packets, both payload and signalling, transmitted in the TDM to the PSN direction. The count includes packets whose L bit is set and which may therefore not contain a payload. (R) (mandatory) (4 bytes) +- Missing packets:** This attribute counts the number of lost packets, as indicated by gaps in the control word numbering sequence. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Misordered packets, usable:** This attribute counts the number of packets received out of order, but which were able to be successfully re-ordered and played out. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Misordered packets dropped:** This attribute counts the number of packets received out of sequence that were discarded, either because the ONU did not support reordering or because it was too late to reorder them. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Playout buffer underruns/overruns:** This attribute counts the number of packets that were discarded because they arrived too late or too early to be played out. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Malformed packets:** This attribute counts the number of malformed packets, e.g., because the packet length was not as expected or because of an unexpected RTP payload type. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Stray packets:** This attribute counts the number of packets whose ECID or RTP SSRC failed to match the expected value, or which are otherwise known to have been misdelivered. Stray packets are discarded without affecting any of the other PM counters. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- Remote packet loss:** This attribute counts received packets whose R bit is set, indicating the loss of packets at the far end. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- TDM L-bit packets transmitted:** This attribute counts the number of packets transmitted with the L bit set, indicating a near-end TDM fault. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- ES:** This attribute counts errored seconds. Any discarded, lost, malformed or unusable packet received from the PSN during a given second causes this counter to increment. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- SES:** This attribute counts severely errored seconds. The criterion for an SES may be configured through the pseudowire maintenance profile ME. Both payload and signalling packets, if any, contribute to this count. (R) (mandatory) (4 bytes) +- UAS:** This attribute counts unavailable seconds. An unavailable second begins at the onset of 10 consecutive SES and ends at the onset of 10 consecutive seconds + +that are not severely errored. A service is unavailable if either its payload or its signalling, if any, are unavailable. During unavailable time, only UAS should be counted; other anomalies should not be counted. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|---------------------|-----------------------------------|---------------------------------------------| +| 0 | Missing packets | 1 | +| 1 | Misordered packets, usable | 2 | +| 2 | Misordered packets dropped | 3 | +| 3 | Playout buffer underruns/overruns | 4 | +| 4 | Malformed packets | 5 | +| 5 | Stray packets | 6 | +| 6 | Remote packet loss | 7 | +| 7 | ES | 8 | +| 8 | SES | 9 | +| 9 | UAS | 10 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### **9.8.9 Ethernet flow termination point** + +The Ethernet flow TP contains the attributes necessary to originate and terminate Ethernet frames in the ONU. It is appropriate when transporting pseudowire services via layer 2. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +One Ethernet flow TP ME exists for each distinct pseudowire service that is transported via layer 2. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to a pseudowire TP ME. (R, set-by-create) (mandatory) (2 bytes) + +**Destination MAC:** This attribute specifies the destination MAC address of upstream Ethernet frames. (R, W, set-by-create) (mandatory) (6 bytes) + +**Source MAC:** This attribute specifies the near-end MAC address. It is established by non-OMCI means (e.g., factory programmed into ONU flash memory) and is included here for information only. (R) (mandatory) (6 bytes) + +**Tag policy:** This attribute specifies the tagging policy to be applied to upstream Ethernet frames. + +- 0 untagged frame +- 1 tagged frame + +(R, W, set-by-create) (mandatory) (1 byte) + +**TCI:** If the tag policy calls for tagging of upstream Ethernet frames, this attribute specifies the tag control information, which includes the VLAN tag, P bits and CFI bit. (R, W) (optional) (2 bytes) + +**Loopback:** This attribute sets the loopback configuration as follows. + +- 0 No loopback +- 1 Loopback of downstream traffic at MAC client + +(R, W) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.8.10 This clause is intentionally left blank** + +### **9.8.11 This clause is intentionally left blank** + +### **9.8.12 CES physical interface performance monitoring history data 2** + +This ME collects far-end statistics for a CES physical interface. It is specifically directed at DS1 interfaces ([b-ATIS-0300231], [b-ATIS-0600403]), but may be useful in other cases as well. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with one instance of the PPTP CES UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP CES UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contain PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +Each of the following attributes is (R) (optional) (2 bytes). + +| Attribute name | Common acronym | +|------------------------------------------------|----------------| +| Errored seconds, line far-end | ES-LFE | +| Code violations, path far-end | CV-PFE | +| Errored seconds, path far-end | ES-PFE | +| Errored seconds type A, path far-end | ESA-PFE | +| Errored seconds type B, path far-end | ESB-PFE | +| Severely errored seconds, path far-end | SES-PFE | +| Severely errored framing seconds, path far-end | SEFS-PFE | +| Unavailable seconds, path far-end | UAS-PFE | + +| Attribute name | Common acronym | +|---------------------------------------|----------------| +| Controlled slip seconds, path far-end | CSS-PFE | +| Failure count, path far-end | FC-PFE | + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | ES-LFE | 1 | +| 1 | CV-PFE | 2 | +| 2 | ES-PFE | 3 | +| 3 | ESA-PFE | 4 | +| 4 | ESB-PFE | 5 | +| 5 | SES-PFE | 6 | +| 6 | SEFS-PFE | 7 | +| 7 | UAS-PFE | 8 | +| 8 | CSS-PFE | 9 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.8.13 CES physical interface performance monitoring history data 3 + +This ME collects auxiliary statistics for a CES physical interface. It is specifically directed at DS1 interfaces ([b-ATIS-0300231], [b-ATIS-0600403]), but may be useful in other cases as well. + +Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with one instance of the PPTP CES UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP CES UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +Each of the following attributes is (R) (optional) (2 bytes). + +| Attribute name | Common acronym | +|-----------------------------------------------|----------------| +| AIS-CI seconds | AISSCI-P | +| Errored seconds, network performance | ES-NP | +| Severely errored seconds, network performance | SES-NP | +| Unavailable seconds, network performance | UAS-NP | +| Errored seconds, network performance, far-end | ES-NPFE | +| Severely errored seconds, NP far-end | SES-NPFE | +| Unavailable seconds, NP far-end | UAS-NPFE | +| Failure count | FC | +| Protection switch count | PSC | +| Protection switch duration | PSD | + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | AISSCI-P | 1 | +| 1 | ES-NP | 2 | +| 2 | SES-NP | 3 | +| 3 | UAS-NP | 4 | +| 4 | ES-NPFE | 5 | +| 5 | SES-NPFE | 6 | +| 6 | UAS-NPFE | 7 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.8.14 MPLS pseudowire termination point + +This ME contains the configuration data of a pseudowire whose underlying transport method is MPLS. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +Zero or one instance of this ME is associated with each instance of the pseudowire TP ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**TP type:** This attribute specifies the type of ANI-side TP associated with this ME. + +- 1 Ethernet flow termination point +- 2 GEM IW TP +- 3 TCP/UDP config data +- 4 MPLS pseudowire termination point + +NOTE – If this instance of the MPLS PW TP is pointed to by another instance of the MPLS PW TP (i.e., whose TP type = 4), this instance represents a tunnelled MPLS flow, and the following attributes are not meaningful: MPLS PW direction; MPLS PW uplink label; MPLS PW downlink label; and MPLS PW TC. These attributes should be set to the proper number of 0x00 bytes by the OLT and ignored by the ONU. + +(R, W, set-by-create) (mandatory) (1 byte) + +**TP pointer:** This attribute points to the instance of the TP associated with this MPLS PW TP. The type of the associated TP is determined by the TP type attribute. (R, W, set-by-create) (mandatory) (2 bytes) + +**MPLS label indicator:** This attribute specifies the MPLS label stacking situation. + +- 0 Single MPLS labelled +- 1 Double MPLS labelled + +(R, W, set-by-create) (mandatory) (1 byte) + +**MPLS PW direction:** This attribute specifies the inner MPLS direction. + +- 0 Upstream only +- 1 Downstream only +- 2 Bidirectional + +(R, W, set-by-create) (mandatory) (1 byte) + +**MPLS PW uplink label:** This attribute specifies the label of the inner MPLS pseudowire upstream. The attribute is not meaningful for unidirectional downstream PWs. (R, W, set-by-create) (mandatory) (4 bytes) + +**MPLS PW downlink label:** This attribute specifies the label of the inner MPLS pseudowire downstream. The attribute is not meaningful for unidirectional upstream PWs. (R, W, set-by-create) (mandatory) (4 bytes) + +**MPLS PW TC:** This attribute specifies the inner MPLS TC value in the upstream direction. The attribute is not meaningful for unidirectional downstream PWs. (R, W, set-by-create) (mandatory) (1 byte) + +NOTE 1 – The TC field was previously known as EXP. Refer to [b-IETF RFC 5462]. + +**MPLS tunnel direction:** This attribute specifies the direction of the (outer) MPLS tunnel. + +- 0 Upstream only +- 1 Downstream only +- 2 Bidirectional + +(R, W, set-by-create) (mandatory for double-labelled case) (1 byte) + +**MPLS tunnel uplink label:** This attribute specifies the (outer) label for the upstream MPLS tunnel. If the MPLS tunnel is downstream only, this attribute should be set to 0. (R, W, set-by-create) (mandatory for double-labelled case) (4 bytes) + +**MPLS tunnel downlink label:** This attribute specifies the (outer) label for the downstream MPLS tunnel. If the MPLS tunnel is upstream only, this attribute should be set to 0. (R, W, set-by-create) (mandatory for double-labelled case) (4 bytes) + +**MPLS tunnel TC:** This attribute specifies the TC value of the upstream MPLS tunnel. If the MPLS tunnel is downstream only, this attribute should be set to 0. (R, W, set-by-create) (mandatory for double MPLS labelled case) (1 byte) + +NOTE 2 – The TC field was previously known as EXP. Refer to [b-IETF RFC 5462]. + +**Pseudowire type:** This attribute specifies the emulated service to be carried over this PW. The values are from [IETF RFC 4446]. + +- 2 ATM AAL5 SDU VCC transport + +- 3 ATM transparent cell transport +- 5 Ethernet +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode +- 14 ATM AAL5 PDU VCC transport + +All other values are reserved. + +(R, W, set-by-create) (mandatory) (2 bytes) + +**Pseudowire control word preference:** When set to true, this Boolean attribute specifies that a control word is to be sent with each packet. Some PW types mandate the use of a control word in any event. In such cases, the value configured for this attribute has no effect on the presence of the control word. (R, W, set-by-create) (optional) (1 byte) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by the MPLS pseudowire TP. Administrative state is further described in clause A.1.6. (R, W) (optional) (1 byte) + +**Operational state:** This attribute reports whether the ME is currently capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------| +| 1..14 | N/A | | +| 15 | Op state | Operational state | +| 16 | Reserved | | + +### **9.8.15 PW ATM configuration data** + +This ME contains generic configuration data for an ATM pseudowire. Definitions of attributes are from PW-ATM-MIB [IETF RFC 5605]. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with an instance of the MPLS pseudowire TP ME with a pseudowire type attribute equal to one of the following. + +- 2 ATM AAL5 SDU VCC transport +- 3 ATM transparent cell transport +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode +- 14 ATM AAL5 PDU VCC transport + +Alternatively, an instance of this ME may be associated with an Ethernet flow TP or a TCP/UDP config data ME, depending on the transport layer of the pseudowire. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**TP type:** This attribute specifies the type of the underlying transport layer. (R, W, set-by-create) (mandatory) (1 byte) + +- 0 MPLS pseudowire termination point +- 1 Ethernet flow termination point +- 2 TCP/UDP config data + +**Transport TP pointer:** This attribute points to an associated instance of the transport layer TP, whose type is specified by the TP type attribute. (R, W, set-by-create) (mandatory) (2 bytes) + +**PPTP ATM UNI pointer:** This attribute points to an associated instance of the ITU-T G.983.2 PPTP ATM UNI. Refer to [ITU-T G.983.2] for the definition of the target ME. (R, W, set-by-create) (mandatory) (2 bytes) + +**Max cell concatenation:** This attribute specifies the maximum number of ATM cells that can be concatenated into one PW packet in the upstream direction. (R, W, set-by-create) (mandatory) (2 bytes) + +**Far-end max cell concatenation:** This attribute specifies the maximum number of ATM cells that can be concatenated into one PW packet as provisioned at the far end. This attribute may be used for error checking of downstream traffic. The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (2 bytes) + +**ATM cell loss priority (CLP) QoS mapping:** This attribute specifies whether the CLP bits should be considered when setting the value in the QoS fields of the encapsulating protocol (e.g., TC fields of the MPLS label stack). + +- 1 ATM CLP bits mapping to QoS fields of the encapsulating protocol +- 2 Not applicable + +The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (1 byte) + +**Timeout mode:** This attribute specifies whether a packet is transmitted in the upstream direction based on timeout expiration for collecting cells. The actual handling of the timeout is implementation specific; as such, this attribute may be changed at any time with proper consideration of the traffic disruption effect. + +- 1 Disabled. The ONU does not generate packets based on timeout cells. +- 2 Enabled. The ONU generates packets based on timeout cells. + +The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (1 byte) + +**PW ATM mapping table:** This attribute lists ATM VPI/VCI mapping entries in both the upstream and downstream directions. In the upstream direction, ATM cells that match no entry's upstream VPI (and conditionally VCI) values are discarded; conversely in the downstream direction. Upon ME instantiation, the ONU sets this attribute to an empty table, which discards all cells in both directions. + +The table can contain up to $N$ entries when the pseudowire type is equal to one of the following: + +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport + +The table contains only one entry when the pseudowire type is equal to one of the following. + +- 2 ATM AAL5 SDU VCC transport +- 3 ATM transparent cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode +- 14 ATM AAL5 PDU VCC transport + +Each entry contains: + +**Entry number:** (1 byte), the index of this row. A set operation with all fields zero has the effect of clearing the table. A set operation with a non-zero entry number and all other fields zero, has the effect of deleting one row. + +**Upstream VPI:** (2 bytes) + +The VPI value of this ATM PW at the UNI. When pseudowire type = ATM transparent cell transport (3), this field is ignored. + +**Upstream VCI:** (2 bytes) + +The VCI value of this ATM PW at the UNI. When pseudowire type = ATM transparent cell transport (3), or in virtual path (VP) cases, this field is ignored. + +**Upstream traffic descriptor profile pointer:** (2 bytes) + +A pointer to an instance of an ITU-T G.983.2 traffic descriptor profile ME that contains the traffic parameters used for the ATM upstream traffic. Refer to clause 7.5.2 of [ITU-T G.983.2] for the definition of this class of MEs. A null pointer indicates BE. + +**Upstream mapped VPI:** (2 bytes) + +The VPI value of the upstream MPLS ATM PW. This field is valid when the pseudowire type is as follows. + +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode + +This field is not used for other pseudowire types. + +**Upstream mapped VCI:** (2 bytes) + +The VCI value of the upstream MPLS ATM PW. This field is valid when the pseudowire type is as follows. + +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode + +This field is not used for other pseudowire types. + +##### **Downstream VPI: (2 bytes)** + +The downstream VPI value of this MPLS ATM PW. When pseudowire type = ATM transparent cell transport (3), this field is ignored. + +##### **Downstream VCI: (2 bytes)** + +The downstream VCI value of this MPLS ATM PW. When pseudowire type = ATM transparent cell transport (3) or in the VP case, this field is ignored. + +##### **Downstream traffic descriptor profile pointer: (2 bytes)** + +A pointer to an instance of an ITU-T G.983.2 traffic descriptor profile ME that contains the traffic parameters used for the ATM downstream traffic. Refer to clause 7.5.2 of [ITU-T G.983.2] for definition of this class of MEs. A null pointer indicates BE. + +##### **Downstream mapped VPI: (2 bytes)** + +The VPI value of this ATM PW at the UNI. This field is valid when the pseudowire type is as follows. + +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode + +This field is not used for other pseudowire types. + +##### **Downstream mapped VCI: (2 bytes)** + +The VCI value of this ATM PW at the UNI. This field is valid when the pseudowire type is as follows. + +- 9 ATM *n*-to-one VCC cell transport +- 10 ATM *n*-to-one VPC cell transport +- 12 ATM one-to-one VCC cell mode +- 13 ATM one-to-one VPC cell mode + +This field is not used for other pseudowire types. + +(R, W) (mandatory) (21*N* bytes, where *N* is the number of entries in the list) + +#### *Actions* + +- Create, delete, get, get next, set +- Set table (optional) + +#### *Notifications* + +None. + +### **9.8.16 PW ATM performance monitoring history data** + +This ME collects PM data associated with an ATM pseudowire. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of the PW ATM configuration data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to the instance of the PW ATM configuration data ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Downstream missing packets counter:** This attribute counts missing packets, as detected via control word sequence number gaps. (R) (mandatory) (4 bytes) + +**Downstream reordered packets counter:** This attribute counts packets detected out of sequence via the control word sequence number, but successfully reordered. Some implementations may not support this feature. (R) (optional) (4 bytes) + +**Downstream misordered packets counter:** This attribute counts packets detected out of order via the control word sequence numbers. (R) (mandatory) (4 bytes) + +**Upstream timeout packets counter:** This attribute counts packets transmitted due to timeout expiration while attempting to collect cells. (R) (mandatory) (4 bytes) + +**Upstream transmitted cells counter:** This attribute counts transmitted cells. (R) (mandatory) (4 bytes) + +**Upstream dropped cells counter:** This attribute counts dropped cells. (R) (mandatory) (4 bytes) + +**Upstream received cells counter:** This attribute counts received cells. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|------------------------------|--------------------------------------| +| 1 | Downstream missing packets | 1 | +| 2 | Downstream reordered packets | 2 | +| 3 | Downstream timeout packets | 3 | +| 4 | Upstream dropped cells | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.8.17 PW Ethernet configuration data + +This ME contains the Ethernet pseudowire configuration data. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with an instance of the MPLS pseudowire TP ME with a pseudowire type attribute equal to the following. + +5 Ethernet + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**MPLS pseudowire TP pointer:** This attribute points to an instance of the MPLS pseudowire TP ME associated with this ME. (R, W, set-by-create) (mandatory) (2 bytes) + +**TP type:** This attribute identifies the type of UNI associated with this Ethernet PW. Valid values are as follows. + +- 1 Physical path termination point Ethernet UNI + - 3 IEEE 802.1p mapper service profile + - 7 Physical path termination point xDSL UNI part 1 + - 11 Virtual Ethernet interface point + - 12 Physical path termination point MoCA UNI + - 13 MAC bridge port configuration data +- Other values are reserved + +(R, W, set-by-create) (mandatory) (1 byte) + +**UNI pointer:** This attribute points to the associated instance of a UNI-side ME. The type of UNI is determined by the TP type attribute. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.8.18 Ethernet pseudowire parameters + +This ME contains the Ethernet pseudowire parameters. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with an instance of the PW Ethernet configuration data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PW Ethernet configuration data ME. (R, set-by-create) (mandatory) (2 bytes) + +**MTU:** This attribute identifies the maximum transmission unit (bytes) that can be received from the CPE in the upstream direction. Larger frames are discarded. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +## **9.9 Voice services** + +This clause defines MEs associated with a POTS (VoIP service), as shown in Figure 9.9-1. + +![Figure 9.9-1: Managed entities associated with a POTS (VoIP service). This is a complex relationship diagram showing various Managed Entities (MEs) and their associations. Central to the diagram is the 'PPTP POTS UNI' (9.9.1). Above it, 'Call control PM history data' (9.9.12) and 'VoIP line status' (9.9.11) point to it with dashed arrows. To its right, 'RTP PM history data' (9.9.13) also points to it with a dashed arrow. Below 'PPTP POTS UNI' is 'VoIP voice CTP' (9.9.4), which has a solid arrow pointing up to the UNI and a dashed arrow pointing down to 'VoIP media profile' (9.9.5). 'VoIP media profile' has a solid arrow pointing down to 'Voice service profile' (9.9.6) and a dashed arrow pointing right to 'RTP profile data' (9.9.7). 'RTP profile data' has a dashed arrow pointing down to 'Voice service profile'. Below 'VoIP voice CTP' is 'MGC configuration data' (9.9.16), which has a solid arrow pointing up to the CTP and a dashed arrow pointing down to it from 'MGC PM history data' (9.9.17). 'MGC configuration data' has a solid arrow pointing right to a list of points: '(2x) Network address' and 'TCP/UDP configuration data'. Below 'MGC configuration data' are 'SIP configuration portal' (9.9.19) and 'MGC configuration portal' (9.9.20), both with solid arrows pointing up to the MGC configuration data. To the right of 'PPTP POTS UNI' is 'SIP user data' (9.9.2), which has a solid arrow pointing up to the UNI and a dashed arrow pointing down to it from 'SIP call initiation PM history data' (9.9.15). 'SIP user data' has a solid arrow pointing right to a list of points: 'Authentication security method', 'Large string (AoR)', and 'Network address'. Below 'SIP user data' is 'SIP agent configuration data' (9.9.3), which has a solid arrow pointing up to the SIP user data and a dashed arrow pointing down to it from 'SIP agent PM history data' (9.9.14). 'SIP agent configuration data' has a solid arrow pointing right to a list of points: '(3x) Large string', 'Network address', and 'TCP/UDP configuration data'. Below 'SIP user data' is 'VoIP application service profile' (9.9.8), which has a solid arrow pointing up to the SIP user data and a dashed arrow pointing down to it from 'VoIP feature access codes' (9.9.9). 'VoIP application service profile' has a solid arrow pointing right to a list of points: '(3x) Network address'. Below 'VoIP application service profile' is 'SIP agent configuration data' (9.9.3), which has a solid arrow pointing up to the VoIP application service profile. To the right of 'SIP user data' is 'Network dial plan table' (9.9.10), which has a solid arrow pointing up to the SIP user data. Below 'SIP user data' is 'VoIP feature access codes' (9.9.9), which has a solid arrow pointing up to the SIP user data. Below 'VoIP feature access codes' is 'SIP call initiation PM history data' (9.9.15), which has a solid arrow pointing up to the VoIP feature access codes. Below 'SIP call initiation PM history data' is 'SIP agent PM history data' (9.9.14), which has a solid arrow pointing up to the SIP call initiation PM history data. Below 'SIP agent PM history data' is 'VoIP config data' (9.9.18), which has a solid arrow pointing up to the SIP agent PM history data and a solid arrow pointing right to a list of points: 'Network address'. Below 'VoIP config data' is 'SIP configuration portal' (9.9.19) and 'MGC configuration portal' (9.9.20), both with solid arrows pointing up to the VoIP config data. The diagram is labeled 'G.988(12)_F9.9-1' in the bottom right corner.](b4fcfeb624b8d8716809e5f9cedb2b1f_img.jpg) + +Figure 9.9-1: Managed entities associated with a POTS (VoIP service). This is a complex relationship diagram showing various Managed Entities (MEs) and their associations. Central to the diagram is the 'PPTP POTS UNI' (9.9.1). Above it, 'Call control PM history data' (9.9.12) and 'VoIP line status' (9.9.11) point to it with dashed arrows. To its right, 'RTP PM history data' (9.9.13) also points to it with a dashed arrow. Below 'PPTP POTS UNI' is 'VoIP voice CTP' (9.9.4), which has a solid arrow pointing up to the UNI and a dashed arrow pointing down to 'VoIP media profile' (9.9.5). 'VoIP media profile' has a solid arrow pointing down to 'Voice service profile' (9.9.6) and a dashed arrow pointing right to 'RTP profile data' (9.9.7). 'RTP profile data' has a dashed arrow pointing down to 'Voice service profile'. Below 'VoIP voice CTP' is 'MGC configuration data' (9.9.16), which has a solid arrow pointing up to the CTP and a dashed arrow pointing down to it from 'MGC PM history data' (9.9.17). 'MGC configuration data' has a solid arrow pointing right to a list of points: '(2x) Network address' and 'TCP/UDP configuration data'. Below 'MGC configuration data' are 'SIP configuration portal' (9.9.19) and 'MGC configuration portal' (9.9.20), both with solid arrows pointing up to the MGC configuration data. To the right of 'PPTP POTS UNI' is 'SIP user data' (9.9.2), which has a solid arrow pointing up to the UNI and a dashed arrow pointing down to it from 'SIP call initiation PM history data' (9.9.15). 'SIP user data' has a solid arrow pointing right to a list of points: 'Authentication security method', 'Large string (AoR)', and 'Network address'. Below 'SIP user data' is 'SIP agent configuration data' (9.9.3), which has a solid arrow pointing up to the SIP user data and a dashed arrow pointing down to it from 'SIP agent PM history data' (9.9.14). 'SIP agent configuration data' has a solid arrow pointing right to a list of points: '(3x) Large string', 'Network address', and 'TCP/UDP configuration data'. Below 'SIP user data' is 'VoIP application service profile' (9.9.8), which has a solid arrow pointing up to the SIP user data and a dashed arrow pointing down to it from 'VoIP feature access codes' (9.9.9). 'VoIP application service profile' has a solid arrow pointing right to a list of points: '(3x) Network address'. Below 'VoIP application service profile' is 'SIP agent configuration data' (9.9.3), which has a solid arrow pointing up to the VoIP application service profile. To the right of 'SIP user data' is 'Network dial plan table' (9.9.10), which has a solid arrow pointing up to the SIP user data. Below 'SIP user data' is 'VoIP feature access codes' (9.9.9), which has a solid arrow pointing up to the SIP user data. Below 'VoIP feature access codes' is 'SIP call initiation PM history data' (9.9.15), which has a solid arrow pointing up to the VoIP feature access codes. Below 'SIP call initiation PM history data' is 'SIP agent PM history data' (9.9.14), which has a solid arrow pointing up to the SIP call initiation PM history data. Below 'SIP agent PM history data' is 'VoIP config data' (9.9.18), which has a solid arrow pointing up to the SIP agent PM history data and a solid arrow pointing right to a list of points: 'Network address'. Below 'VoIP config data' is 'SIP configuration portal' (9.9.19) and 'MGC configuration portal' (9.9.20), both with solid arrows pointing up to the VoIP config data. The diagram is labeled 'G.988(12)\_F9.9-1' in the bottom right corner. + +**Figure 9.9-1 – Managed entities associated with a POTS (VoIP service)** + +### **9.9.1 Physical path termination point POTS UNI** + +This ME represents a POTS UNI in the ONU, where a physical path terminates and physical path level functions (analogue telephony) are performed. + +The ONU automatically creates an instance of this ME per port as follows. + +- When the ONU has POTS ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the POTS type. + +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the POTS type. Note that the installation of a plug-and-play card may indicate the presence of POTS ports via equipment ID as well as type, and indeed may cause the ONU to instantiate a port-mapping package that specifies POTS ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a POTS circuit pack, nor is it equipped with a POTS circuit pack. + +#### *Relationships* + +An instance of this ME is associated with each real or pre-provisioned POTS port. Either a SIP or a VoIP voice CTP links to the POTS UNI. Status is available from a VoIP line status ME, and RTP and call control PM may be collected on this point. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute shuts down (2), locks (1) and unlocks (0) the functions performed by this ME. If the administrative state is set to shut down while the POTS UNI line state is non-idle, no action is taken until the POTS UNI line state changes to idle, whereupon the administrative state changes to locked. If the administrative state is set to shut down and the POTS UNI line state is already idle, the administrative state is immediately set to locked. In both cases, the transition from shutting down to locked state is signalled with an AVC. + +When the administrative state is set to lock, all user functions of this UNI are blocked, and alarms, TCAs and AVCs for this ME and all dependent MEs are no longer generated. Selection of a default value for this attribute is outside the scope of this Recommendation. (R, W) (mandatory) (1 byte) + +**Deprecated:** This attribute is not used and should not be supported. (R, W) (optional) (2 bytes) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Impedance:** This attribute specifies the impedance for the POTS UNI. Valid values include the following. + +- 0 600 Ohm +- 1 900 Ohm + +The following parameter sets from Annex C of [ETSI TS 101 270-1] are also defined: + +- 2 C1=150 nF, R1=750 Ohm, R2=270 Ohm +- 3 C1=115 nF, R1=820 Ohm, R2=220 Ohm +- 4 C1=230 nF, R1=1050 Ohm, R2=320 Ohm + +where C1, R1, and R2 are related as shown in Figure 9.9.1-1. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (1 byte) + +![Circuit diagram of an impedance model for POTS UNI. It shows a transmission line with a shunt branch containing a capacitor C1 and a resistor R1 in series. This is followed by a series resistor R2. The diagram is labeled G.988(12)_F9.9.1-1.](e8244261e5f586f2e608e17ba6548d09_img.jpg) + +Circuit diagram of an impedance model for POTS UNI. It shows a transmission line with a shunt branch containing a capacitor C1 and a resistor R1 in series. This is followed by a series resistor R2. The diagram is labeled G.988(12)\_F9.9.1-1. + +**Figure 9.9.1-1 – Impedance model for POTS UNI** + +**Transmission path:** This attribute allows setting the POTS UNI either to full-time on-hook transmission (0) or part-time on-hook transmission (1). Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (1 byte) + +**Rx gain:** This attribute specifies a gain value for the received signal in the form of a 2s complement number. Valid values are –120 (12.0 dB) to 60 (+6.0 dB). The direction of the affected signal is in the D to A direction, towards the telephone set. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (1 byte) + +**Tx gain:** This attribute specifies a gain value for the transmit signal in the form of a 2s complement number. Valid values are –120 (12.0 dB) to 60 (+6.0 dB). The direction of the affected signal is in the A to D direction, away from the telephone set. Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Hook state:** This attribute indicates the current state of the subscriber line: 0 = on hook, 1 = off hook (R) (optional) (1 byte) + +**POTS holdover time:** This attribute determines the time during which the POTS loop voltage is held up when a LOS or softswitch connectivity is detected (please refer to the following table for description of behaviours). After the specified time elapses, the ONU drops the loop voltage, and may thereby cause premises intrusion alarm or fire panel circuits to go active. When the ONU ranges successfully on the PON or softswitch connectivity is restored, it restores the POTS loop voltage immediately and resets the timer to zero. The attribute is expressed in seconds. The default value 0 selects the vendor's factory policy. (R, W) (optional) (2 bytes) + +| POTS holdover time | Loss of softswitch | Behaviour | +|------------------------|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Don't care | Vendor-specific | +| POTS holdover time > 0 | False | T/R will be brought down on expiration of the holdover timer. The holdover timer is started upon detection of LOS. T/R is restored immediately upon ONU ranging. This setting is recommended for burglar alarms. | +| POTS holdover time > 0 | True | T/R will be brought down on expiration of the holdover timer. The holdover timer is started on detection of softswitch connectivity keep alive signal. T/R is restored immediately upon softswitch connectivity. This setting is recommended for fire panels. | + +**Nominal feed voltage:** This attribute indicates the designed nominal feed voltage of the POTS loop. It is an absolute value with resolution 1 V. This attribute does not represent the actual voltage measured on the loop, which is available through the test command. (R, W) (optional) (1 byte) + +**Loss of softswitch:** This Boolean attribute controls whether the T/R holdover initiation criteria. False disables loss of softswitch connectivity detection as criteria for initiating the POTS holdover timer. True enables loss of softswitch connectivity detection as criteria for initiating the POTS holdover timer. This attribute is optional (if not implemented, the POTS holdover time is triggered on a LOS when POTS holdover is greater than zero). (R, W) (optional) (1 byte) + +#### Actions + +Get, set + +**Test:** Request that the ONU perform one or more mechanized loop tests (MLTs) or a dial tone make/break test. Vendor-specific tests are also supported by the test and test result message layouts in Annex A. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-----------------------------------------------------------------------------------------------| +| 1 | Administrative state | The only change that is signalled with an AVC is the transition from shutting down to locked. | +| 2 | N/A | | +| 3 | ARC | ARC timer expiration | +| 4..8 | N/A | | +| 9 | Op state | Operational state | +| 10..11 | N/A | | +| 12..16 | Reserved | | + +### 9.9.2 SIP user data + +The SIP user data defines the user specific configuration attributes associated with a specific VoIP CTP. This entity is conditionally required for ONUs that offer VoIP SIP services. If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +An instance of this ME is created and deleted by the OLT. A SIP user data instance is required for each POTS UNI port using SIP protocol and configured by the OMCI. + +#### Relationships + +An instance of this ME is associated with one VoIP voice CTP ME and a PTP POTS UNI. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**SIP agent pointer:** This attribute points to the SIP agent config data ME to be used for signalling. (R, W, set-by-create) (mandatory) (2 bytes) + +- User part AOR:** This attribute points to a large string that contains the user identification part of the address of record. This can take the form of an alphanumeric string or the subscriber's directory number. A null pointer indicates the absence of an AOR. (R, W, set-by-create) (mandatory) (2 bytes) +- SIP display name:** This ASCII string attribute defines the customer ID used for the display attribute in outgoing SIP messages. The default value is null (all zero bytes) (R, W) (mandatory) (25 bytes) +- Username and password:** This attribute points to an authentication security method ME that contains the SIP user name and password used for authentication. A null pointer indicates no username and password. (R, W, set-by-create) (mandatory) (2) +- Voicemail server SIP URI:** This attribute points to a network address ME that contains the name (IP address or URI) of the SIP voicemail server for SIP signalling messages. A null pointer indicates the absence of a SIP voicemail server. (R, W, set-by-create) (mandatory) (2 bytes) +- Voicemail subscription expiration time:** This attribute defines the voicemail subscription expiration time in seconds. If this value is 0, the SIP agent uses an implementation-specific value. This attribute is recommended to be set to 3600 s by default. (R, W, set-by-create) (mandatory) (4 bytes) +- Network dial plan pointer:** This attribute points to a network dial plan table. A null pointer indicates the absence of a network dial plan. (R, W, set-by-create) (mandatory) (2 bytes) +- Application services profile pointer:** This attribute points to a VoIP application services profile. (R, W, set-by-create) (mandatory) (2 bytes) +- Feature code pointer:** This attribute points to the VoIP feature access codes ME for this subscriber. A null pointer indicates the absence of a VoIP feature access codes ME. (R, W, set-by-create) (mandatory) (2 bytes) +- PPTP pointer:** This attribute points to the PPTP POTS UNI ME that provides the analogue telephony adaptor (ATA) function. (R, W, set-by-create) (mandatory) (2 bytes) +- Release timer:** This attribute contains a release timer defined in seconds. The value 0 specifies that the ONU is to use its internal default. The default value of this attribute is 10 s. (R, W) (optional) (1 byte) +- Receiver off hook (ROH) timer:** This attribute defines the time in seconds for the ROH condition before ROH tone is applied. The value 0 disables ROH timing. The value 0xFF specifies that the ONU is to use its internal default, which may or may not be the same as the 15 s OMCI default value. (R, W) (optional) (1 byte) + +#### Actions + +Create, delete, get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|----------------------|------------------------------------------------------------------------| +| 0 | SIP UA register auth | Cannot authenticate a registration session (e.g., missing credentials) | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-------------------------|---------------------------------------------------------| +| 1 | SIP UA register timeout | Timeout waiting for response from a registration server | +| 2 | SIP UA register fail | Failure response received from a registration server | +| 3 | SIPUA missing dial plan | Missing dial plan | +| 4 | SIPUA invalid dial plan | Invalid dial plan | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.9.3 SIP agent config data + +The SIP agent config data ME models a SIP signalling agent. It defines the configuration necessary to establish communication for signalling between the SIP user agent (UA) and a SIP server. + +NOTE 1 – If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. The non-OMCI interface supplies the necessary data, which may be read back to the OLT via the SIP config portal ME. + +Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME serves one or more SIP user data MEs and points to a TCP/UDP config data that carries signalling messages. Other pointers establish additional agent parameters such as proxy servers. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Proxy server address pointer:** This attribute points to a large string ME that contains the name (IP address or URI) of the SIP proxy server for SIP signalling messages. (R, W, set-by-create) (mandatory) (2 bytes) + +**Outbound proxy address pointer:** An outbound SIP proxy may or may not be required within a given network. If an outbound SIP proxy is used, the outbound proxy address pointer attribute must be set to point to a valid large string ME that contains the name (IP address or URI) of the outbound proxy server for SIP signalling messages. If an outbound SIP proxy is not used, the outbound proxy address pointer attribute must be set to a null pointer. (R, W, set-by-create) (mandatory) (2 bytes) + +**Primary SIP DNS:** This attribute specifies the primary SIP DNS IP address. If the value of this attribute is 0, the primary DNS server is defined in the corresponding IP host config data or IPv6 host config data ME. If the value is non-zero, it takes precedence over the primary DNS server defined in the IP host config data or IPv6 host config data ME. (R, W, set-by-create) (mandatory) (4 bytes) + +**Secondary SIP DNS:** This attribute specifies the secondary SIP DNS IP address. If the value of this attribute is 0, the secondary DNS server is defined in the corresponding IP host config data or IPv6 host config data ME. If the value is non-zero, it takes precedence over the secondary DNS server defined in the IP host config data or IPv6 host config data ME. (R, W, set-by-create) (mandatory) (4 bytes) + +**TCP/UDP pointer:** This pointer associates the SIP agent with the TCP/UDP config data ME to be used for communication with the SIP server. The default value is 0xFFFF, a null pointer. (R, W) (mandatory) (2 bytes) + +**SIP reg exp time:** This attribute specifies the SIP registration expiration time in seconds. If its value is 0, the SIP agent does not add an expiration time to the registration requests and does not perform re-registration. The default value is 3600 s. (R, W) (mandatory) (4 bytes) + +**SIP rereg head start time:** This attribute specifies the time in seconds prior to timeout that causes the SIP agent to start the re-registration process. The default value is 360 s. (R, W) (mandatory) (4 bytes) + +**Host part URI:** This attribute points to a large string ME that contains the host or domain part of the SIP address of record for users connected to this ONU. A null pointer indicates that the current address in the IP host config ME is to be used. (R, W, set-by-create) (mandatory) (2 bytes) + +**SIP status:** This attribute shows the current status of the SIP agent. Values are as follows. + +- 0 Ok/initial +- 1 Connected +- 2 Failed – ICMP error +- 3 Failed – Malformed response +- 4 Failed – Inadequate info response +- 5 Failed – Timeout +- 6 Redundant, offline: this instance of the SIP agent config data occupies the role of a redundant server, and is not presently in use. + +(R) (mandatory) (1 byte) + +**SIP registrar:** This attribute points to a network address ME that contains the name (IP address or resolved name) of the registrar server for SIP signalling messages. Examples: "10.10.10.10" and "proxy.voip.net". (R, W, set-by-create) (mandatory) (2 bytes) + +**Softswitch:** This attribute identifies the SIP gateway softswitch vendor. The format is four ASCII coded alphabetic characters [A..Z] as defined in [ATIS-0300220]. A value of four null bytes indicates an unknown or unspecified vendor. (R, W, set-by-create) (mandatory) (4 bytes) + +**SIP response table:** This attribute specifies the tone and text to be presented to the subscriber upon receipt of various SIP messages (normally 4xx, 5xx, 6xx message codes). The table is a sequence of entries, each of which is defined as follows. + +**SIP response code** (2 bytes): This field is the value of the SIP message code. It also serves as the index into the SIP response table. When a set operation is performed with the value 0 in this field, the table is cleared. + +**Tone** (1 byte): This field specifies one of the tones in the tone pattern table of the associated voice service profile. The specified tone is played to the subscriber. + +**Text message** (2 bytes): This field is a pointer to a large string that contains a message to be displayed to the subscriber. If the value of this field is a null pointer, text pre-associated with the tone may be displayed, or no text at all. + +(R, W) (optional) ( $N * 5$ bytes) + +NOTE 2 – This model assumes that SIP response tones and text are common to all POTS lines that share a given SIP agent. + +**SIP option transmit control:** This Boolean attribute specifies that the ONU is (true) or is not (false) enabled to transmit SIP options. The default value is recommended to be false. (R, W, set-by-create) (optional) (1 byte) + +**SIP URI format:** This attribute specifies the format of the URI in outgoing SIP messages. The recommended default value 0 specifies TEL URIs; the value 1 specifies SIP URIs. Other values are reserved. (R, W, set-by-create) (optional) (1 byte) + +**Redundant SIP agent pointer:** This attribute points to another SIP agent config data ME, which is understood to provide redundancy. The initial SIP agent is determined by the pointer from the SIP user data ME. It is the manager's responsibility to provision a group of redundant SIP agents with mutually consistent attributes. (R, W, set-by-create) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Set table (optional) + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|---------------| +| 1..8 | N/A | | +| 9 | SIP status | Status change | +| 10..11 | N/A | | +| 12..16 | Reserved | | + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|--------------------------|---------------------------------------------------------------------------------------------------------------| +| 0 | SIP UA register name | Failed to resolve the registration server name | +| 1 | SIP UA register reach | Cannot reach a registration server (the port cannot be reached, ICMP errors) | +| 2 | SIP UA register connect | Cannot connect to a registration server (due to bad credentials or other faults after the port has responded) | +| 3 | SIP UA register validate | Cannot validate a registration server | +| 4 (Note) | SIP UA register auth | Cannot authenticate a registration session (e.g., missing credentials) | +| 5 (Note) | SIP UA register timeout | Timeout waiting for response from a registration server | +| 6 (Note) | SIP UA register fail | Failure response received from a registration server | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +NOTE – These alarms are deprecated, and retained for backward compatibility. It is recommended that the SIP agent config data not declare these alarms, but that they be declared by the SIP user data ME instead. In any event, only one ME should declare the alarm, not both. + +### 9.9.4 VoIP voice CTP + +The VoIP voice CTP defines the attributes necessary to associate a specified VoIP service (SIP, ITU-T H.248) with a POTS UNI. This entity is conditionally required for ONUs that offer VoIP services. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. + +An instance of this ME is created and deleted by the OLT. A VoIP voice CTP ME is needed for each PTP POTS UNI served by VoIP. + +#### *Relationships* + +An instance of this ME links a PTP POTS UNI ME with a VoIP media profile and a SIP user data or media gateway controller (MGC) config data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**User protocol pointer:** This attribute points to signalling protocol data. If the signalling protocol used attribute of the VoIP config data ME specifies that the ONU's signalling protocol is SIP, this attribute points to a SIP user data ME, which in turn points to a SIP agent config data ME. If the signalling protocol is ITU-T H.248, this attribute points directly to an MGC config data ME. (R, W, set-by-create) (mandatory) (2 bytes) + +**PTP pointer:** This attribute points to the PTP POTS UNI ME that serves the analogue telephone port. (R, W, set-by-create) (mandatory) (2 bytes) + +**VoIP media profile pointer:** This attribute points to an associated VoIP media profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Signalling code:** This attribute specifies the POTS-side signalling as follows. + +- 1 Loop start +- 2 Ground start +- 3 Loop reverse battery +- 4 Coin first +- 5 Dial tone first +- 6 Multi-party + +(R, W, set-by-create) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.9.5 VoIP media profile + +The VoIP media profile ME contains settings that apply to VoIP voice encoding. This entity is conditionally required for ONUs that offer VoIP services. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. + +An instance of this ME is created and deleted by the OLT. A VoIP media profile is needed for each unique set of profile attributes. + +#### *Relationships* + +An instance of this ME may be associated with one or more VoIP voice CTP MEs. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Fax mode:** Selects the fax mode; values are as follows. + +- 0 Passthru +- 1 ITU-T T.38 + +(R, W, set-by-create) (mandatory) (1 byte) + +**Voice service profile pointer:** Pointer to a voice service profile, which defines parameters such as jitter buffering and echo cancellation. (R, W, set-by-create) (mandatory) (2 bytes) + +**Codec selection (1st order):** This attribute specifies codec selection as defined by [IETF RFC 3551]. + +| Value | Encoding name | Clock rate (Hz) | +|-------|-----------------|-----------------| +| 0 | PCMU | 8000 | +| 1 | reserved | | +| 2 | reserved | | +| 3 | GSM | 8000 | +| 4 | ITU-T G.723 | 8000 | +| 5 | DVI4 | 8000 | +| 6 | DVI4 | 16000 | +| 7 | LPC | 8000 | +| 8 | PCMA | 8000 | +| 9 | ITU-T G.722 | 8000 | +| 10 | L16, 2 channels | 44100 | +| 11 | L16, 1 channel | 44100 | +| 12 | QCELP | 8000 | +| 13 | CN | 8000 | +| 14 | MPA | 90000 | +| 15 | ITU-T G.728 | 8000 | +| 16 | DVI4 | 11025 | +| 17 | DVI4 | 22050 | +| 18 | ITU-T G.729 | 8000 | + +(R, W, set-by-create) (mandatory) (1 byte) + +**Packet period selection (1st order):** This attribute specifies the packet period selection interval in milliseconds. The recommended default value is 10 ms. Valid values are 10..30 ms. (R, W, set-by-create) (mandatory) (1 byte) + +**Silence suppression (1st order):** This attribute specifies whether silence suppression is on or off. Valid values are 0 = off and 1 = on. (R, W, set-by-create) (mandatory) (1 byte) + +Three more groups of three attributes are defined, with definitions identical to the preceding three: + +**Codec selection (2nd order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Packet period selection (2nd order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Silence suppression (2nd order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Codec selection (3rd order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Packet period selection (3rd order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Silence suppression (3rd order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Codec selection (4th order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Packet period selection (4th order):** (R, W, set-by-create) (mandatory) (1 byte) + +**Silence suppression (4th order):** (R, W, set-by-create) (mandatory) (1 byte) + +**OOB DTMF:** This attribute specifies out-of-band DMTF carriage. When enabled (1), DTMF signals are carried out of band via RTP or the associated signalling protocol. When disabled (0), DTMF tones are carried in the PCM stream. (R, W, set-by-create) (mandatory) (1 byte) + +**RTP profile pointer:** This attribute points to the associated RTP profile data ME. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.9.6 Voice service profile** + +This ME organizes data that describe the voice service functions of the ONU. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of a VoIP voice CTP by way of a VoIP media profile. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Announcement type:** This attribute specifies the treatment when a subscriber goes off hook but does not attempt a call within the dial-tone timeout interval. Valid values include the following. + +| | | +|------|----------------------------------------------------| +| 0x01 | Silence | +| 0x02 | Reorder tone | +| 0x03 | Fast busy | +| 0x04 | Voice announcement | +| 0xFF | Not specified; ONU is free to make its own choice. | + +(R, W, set-by-create) (mandatory) (1 byte) + +**Jitter target:** This attribute specifies the target value of the jitter buffer in milliseconds. The system tries to maintain the jitter buffer at the target value. The value 0 specifies dynamic jitter buffer sizing. (R, W, set-by-create) (optional) (2 bytes) + +**Jitter buffer max:** This attribute specifies the maximum depth of the jitter buffer associated with this service in milliseconds. The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (2 bytes) + +**Echo cancel ind:** The Boolean value true specifies that echo cancellation is on; false specifies off. (R, W, set-by-create) (mandatory) (1 byte) + +**PSTN protocol variant:** This attribute controls which variant of POTS signalling is used on the associated UNIs. Its value is equal to the [ITU-T E.164] country code. The value 0 specifies that the ONU uses its internal default. (R, W, set-by-create) (optional) (2 bytes) + +**DTMF digit levels:** This attribute specifies the power level of DTMF digits that may be generated by the ONU towards the subscriber set. It is a 2s complement value referred to 1 mW at the 0 transmission level point (TLP) (dBm0), with resolution 1 dB. The default value 0x8000 selects the ONU's internal policy. (R, W, set-by-create) (optional) (2 bytes) + +**DTMF digit duration:** This attribute specifies the duration of DTMF digits that may be generated by the ONU towards the subscriber set. It is specified in milliseconds. The default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (2 bytes) + +**Hook flash minimum time:** This attribute defines the minimum duration recognized by the ONU as a switchhook flash. It is expressed in milliseconds; the default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (2 bytes) + +**Hook flash maximum time:** This attribute defines the maximum duration recognized by the ONU as a switchhook flash. It is expressed in milliseconds; the default value 0 selects the ONU's internal policy. (R, W, set-by-create) (optional) (2 bytes) + +**Tone pattern table:** This attribute is a table, each of whose entries specifies a complex tone (or silence) and a duration. By linking tones and silence together, possibly cyclically, continuous, varying or interrupted tone sequences, repetitive or not, may be defined. A tone sequence is initiated by pointing to the first tone pattern table entry that defines its parameters. Each entry is a vector comprising the following components. + +**Index** (1 byte): This component is simply an index into the table. It ranges from 1..255. In a set operation, the value 0 in this field clears the table. + +**Tone on** (1 byte): This Boolean component controls whether the tone is on (true) or off. If the tone is off, the frequency and power fields are not meaningful. + +**Frequency 1** (2 bytes): This component specifies the frequency of one of the tone components in hertz. + +**Power 1** (1 byte): This component specifies the power level of the corresponding frequency component. It ranges from 0 (coded as 0) to -25.5 (coded as 255) dBm0 with 0.1 dB resolution. + +Three additional pairs of frequency-power components may be specified to define a complex tone. If a pair of possibilities is not to be used, its frequency field should be set to 0. + +**Frequency 2** (2 bytes) + +**Power 2** (1 byte) + +**Frequency 3** (2 bytes) + +**Power 3** (1 byte) + +**Frequency 4** (2 bytes) + +**Power 4** (1 byte) + +The following pair of frequency-power components allows the composite tone to be modulated (warble effect). If this effect is not to be used, the frequency should be set to 0. + +**Modulation frequency** (2 bytes), hertz + +**Modulation power** (1 byte), 0..25.5 dBm0 + +**Duration** (2 bytes): This component specifies the duration of the phase, in milliseconds. The value 0 specifies that the phase endures indefinitely, i.e., until terminated by other events such as call abandonment. + +**Next entry** (1 byte): This component is a pointer to another entry in this same table, which permits sequences of tones to be defined, possibly cyclically. A reference to a non-existent table entry, or the value 0, indicates that the sequence should be terminated. + +(R, W) (optional) ( $N * 20$ bytes) + +**Tone event table:** This attribute is a table, each of whose entries specifies an event for which a tone is defined. If the tone can be synthesized by a sequence of complex tones and silence, the event refers to an entry in the tone pattern table. Otherwise, the event refers to a file name that is expected to be recognized by the ONU environment. Each entry in the tone event table is a vector comprising the following components. + +**Event** (1 byte): This component is an enumeration of the events for which a tone may be defined. The event component also serves as the index for the table. A set operation to event 0 causes the table to be cleared. + +| Value | Tone event | +|-------|--------------------------------------------------------------| +| 0 | Not used for get operation; clears table under set operation | +| 1 | Busy | +| 2 | Confirmation | +| 3 | Dial | +| 4 | Message waiting | +| 5 | Off-hook warning (receiver off hook) | +| 6 | Ringback (audible ring) | +| 7 | Reorder | +| 8 | Stutter dial | +| 9 | Call waiting 1 | +| 10 | Call waiting 2 | +| 11 | Call waiting 3 | +| 12 | Call waiting 4 | +| 13 | Alerting signal | +| 14 | Special dial | +| 15 | Special info | +| 16 | Release | +| 17 | Congestion | + +| Value | Tone event | +|----------|-----------------------------------------------| +| 18 | User defined 1 | +| 19 | User defined 2 | +| 20 | User defined 3 | +| 21 | User defined 4 | +| 22..32 | Reserved | +| 33 | Intrusion | +| 34 | Dead tone | +| 35..223 | Reserved | +| 224..255 | Vendor-specific codes, not to be standardized | + +**Tone pattern** (1 byte): This component specifies an entry point into the tone pattern table attribute, to be invoked when the specified event occurs. The value 0 indicates that no tone from the tone pattern table is to be played. + +**Tone file** (2 bytes): This component points to a large string ME that contains the path and name of a file containing a codec sequence to be played out. If no file is found after traversing these links, no tone is played. The behaviour is unspecified if both tone pattern and tone file are specified. + +**Tone file repetitions** (1 byte): This component specifies the number of times the tone file is to be repeated. The value 0 means that the file is to be repeated indefinitely until terminated by some external event such as call abandonment. + +**Reserved** (2 bytes) + +(R, W) (optional) ( $N * 7$ bytes). + +**Ringing pattern table:** This attribute is a table, each of whose entries specifies a ringing pattern and a duration. By linking ringing and silence together, possibly cyclically, continuous or interrupted ringing sequences, repetitive or not, may be defined. A ringing sequence is initiated by pointing to the first ringing pattern table entry that defines its parameters. Each entry is a vector comprising the following components. + +**Index** (1 byte): This component is simply an index into the table. It ranges from 1..255. In a set operation, the value 0 in this field clears the table. + +**Ringing on** (1 byte): This Boolean component controls whether ringing is on (true) or off during this interval. + +**Duration** (2 bytes): This component specifies the duration of the ringing phase, in milliseconds. The value 0 specifies that the phase endures indefinitely, i.e., until terminated by other events such as call abandonment. + +**Next entry** (1 byte): This component is a pointer to another entry in this same table, which permits sequences of ringing bursts to be defined, possibly cyclically. A reference to a non-existent table entry, or the value 0, indicates that the sequence should be terminated. + +(R, W) (optional) ( $N * 5$ bytes). + +**Ringing event table:** This attribute is a table, each of whose entries specifies an event for which a ringing sequence is defined. If the ringing sequence can be generated as a sequence of power ringing and silent intervals, the event refers to an entry + +in the ringing pattern table. Otherwise, the event refers to a file name that is expected to be recognized by the ONU environment. Each entry is a vector comprising the following components: + +**Event** (1 byte): This component is an enumeration of the events for which a ringing sequence may be defined. The event component also serves as the index for the table. A set operation with the value 0 in this field causes the table to be cleared. + +| Value | Tone event | +|----------|--------------------------------------------------------------| +| 0 | Not used for get operation; clears table under set operation | +| 1 | Default | +| 2 | Splash | +| 3..223 | Reserved | +| 224..255 | Vendor-specific codes, not to be standardized | + +**Ringing pattern** (1 byte): This component specifies an entry point into the ringing pattern table attribute, to be invoked when the specified event occurs. The value 0 indicates that no ringing sequence is defined in the ringing pattern table. + +**Ringing file** (2 bytes): This component points to a large string ME that contains the path and name of a file containing a ring tone to be played out. If no file is found after traversing these links, no ringing is played. The behaviour is unspecified if both ringing pattern and ringing file fields are specified. + +**Ringing file repetitions** (1 byte): This component specifies the number of times the ringing file is to be repeated. The value 0 means that the file is to be repeated indefinitely until terminated by some external event such as call abandonment. + +**Ringing text** (2 bytes): This component points to a large string ME that contains a text string to be displayed on the CPE device in conjunction with this event. A null pointer indicates that no text is to be displayed. + +(R, W) (optional) ( $N * 7$ bytes). + +**Network specific extensions pointer:** This attribute points to a network address ME that contains the path and name of a file containing network specific parameters for the associated UNIs. The default value for this attribute is 0xFFFF, a null pointer. (R, W, set-by-create) (optional) (2 bytes) + +#### Actions + +Create, delete, get, set + +Set table (optional) + +#### Notifications + +##### Alarm + +| Number | Alarm | Description | +|--------|----------------|---------------------------------------------------------------------------------------------------------| +| 1 | File not found | The voice service profile attempted to access a network specific extensions file that is not available. | +| 2..207 | Reserved | | + +### 9.9.7 RTP profile data + +This ME configures RTP. It is conditionally required for ONUs that offer VoIP service. If a non-OMCI interface is used to manage VoIP, this ME is unnecessary. + +An instance of this ME is created and deleted by the OLT. An RTP profile is needed for each unique set of attributes. + +#### *Relationships* + +An instance of this ME may be associated with one or more VoIP media profile MEs. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Local port min:** This attribute defines the base UDP port that should be used by RTP for voice traffic. The recommended default is 50000 (R, W, set-by-create) (mandatory) (2 bytes) + +**Local port max:** This attribute defines the highest UDP port used by RTP for voice traffic. The value must be greater than the local port minimum. The value 0 specifies that the local port maximum be equal to the local port minimum. (R, W, set-by-create) (optional) (2 bytes) + +**DSCP mark:** Diffserv code point to be used for outgoing RTP packets for this profile. The recommended default value is expedited forwarding (EF) = 0x2E. (R, W, set-by-create) (mandatory) (1 byte) + +**Piggyback events:** Enables or disables RTP piggyback events. + +- 0 Disabled (recommended default) +- 1 Enabled + +(R, W, set-by-create) (mandatory) (1 byte) + +**Tone events:** Enables or disables the handling of tones via RTP tone events per [IETF RFC 4733], (see also [IETF RFC 4734]). + +- 0 Disabled (recommended default) +- 1 Enabled + +(R, W, set-by-create) (mandatory) (1 byte) + +**DTMF events:** Enables or disables the handling of DTMF via RTP DTMF events per [IETF RFC 4733], (see also [IETF RFC 4734]). This attribute is ignored unless the OOB DTMF attribute in the VoIP media profile is enabled. + +- 0 Disabled +- 1 Enabled + +(R, W, set-by-create) (mandatory) (1 byte) + +**CAS events:** Enables or disables the handling of CAS via RTP CAS events per [IETF RFC 4733], (see also [IETF RFC 4734]). + +- 0 Disabled +- 1 Enabled + +(R, W, set-by-create) (mandatory) (1 byte) + +**IP host config pointer:** This optional pointer associates the bearer (voice) flow with an IP host config data or IPv6 host config data ME. If this attribute is not present or is not populated with a valid pointer value, the bearer flow uses the same IP stack that is used for signalling, indicated by the TCP/UDP pointer in the + +associated SIP agent or MGC config data. The default value is 0xFFFF, a null pointer. (R, W) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.9.8 VoIP application service profile** + +The VoIP application service profile defines attributes of calling features used in conjunction with a VoIP line service. It is optional for ONUs that support VoIP services. If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. + +An instance of this ME is created and deleted by the OLT. A VoIP application service profile instance is needed for each unique set of profile attributes. + +#### *Relationships* + +An instance of this ME is associated with zero or more SIP user data MEs. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. +(R, set-by-create) (mandatory) (2 bytes) + +**CID features:** This attribute contains a bit map of caller ID features. Except as noted, the bit value 0 disables the feature; 1 enables it. + +| | | +|------------|----------------------------------------------------------------------------------| +| 0x01 | Calling number | +| 0x02 | Calling name | +| 0x04 | CID blocking (both number and name) | +| 0x08 | CID number – Permanent presentation status for number (0 = public, 1 = private) | +| 0x10 | CID name – Permanent presentation status for name (0 = public, 1 = private) | +| 0x20 | Anonymous CID blocking (ACR). It may not be possible to support this in the ONU. | +| 0x40..0x80 | Not used | + +The recommended default value is 0x00. (R, W, set-by-create) (mandatory) (1 byte) + +**Call waiting features:** This attribute contains a bit map of call waiting features. The bit value 0 disables the feature; 1 enables it. + +| | | +|------------|------------------------| +| 0x01 | Call waiting | +| 0x02 | Caller ID announcement | +| 0x04..0x80 | Not used | + +The recommended default value is 0x00. (R, W, set-by-create) (mandatory) (1 byte) + +**Call progress or transfer features:** This attribute is a bit map of call processing features. The bit value 0 disables the feature; 1 enables it. + +| | | +|--------|---------------------------------------------| +| 0x0001 | 3way | +| 0x0002 | Call transfer | +| 0x0004 | Call hold (RFC 3264 sendonly SDP call hold) | +| 0x0008 | Call park | +| 0x0010 | Do not disturb | + +| | | +|----------------|--------------------------------------------------------------------------------------------------------------------------------------| +| 0x0020 | Flash on emergency service call (flash is to be processed during an emergency service call) | +| 0x0040 | Emergency service originating hold (determines whether call clearing is to be performed on on-hook during an emergency service call) | +| 0x0080 | 6way | +| 0x0100 | Call hold (RFC 2543 connection address 0.0.0.0 call hold) | +| 0x0200..0x8000 | Not used | + +The recommended default value is 0x0000. (R, W, set-by-create) (mandatory) (2 bytes) + +**Call presentation features:** This attribute is a bit map of call presentation features. The bit value 0 disables the feature; 1 enables it. + +| | | +|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0x0001 | Message waiting indication splash ring | +| 0x0002 | Message waiting indication special dial tone | +| 0x0004 | Message waiting indication visual indication | +| 0x0008 | Call forwarding indication | +| 0x0010 | DC voltage based visual message waiting indicator (vmwi) (e.g., neon lamp on a phone to indicate a message waiting). For backwards compatibility reasons, the value 0x0010 is a companion value to 0x0004. If an ONU does not support DC voltage vmwi, the ONU uses other existing vmwi methods. If the ONU supports DC voltage vmwi and needs to apply DC voltage to turn on the phone lamp (to indicate message waiting), the values 0x0004 and 0x0010 are set. | +| 0x0020..0x8000 | Not used | + +The recommended default value is 0x0000. (R, W, set-by-create) (mandatory) (2 bytes) + +**Direct connect feature:** This attribute is a bit map of characteristics associated with the direct connect feature. The bit value 0 disables the feature; 1 enables it. + +| | | +|------|--------------------------------| +| 0x01 | Direct connect feature enabled | +| 0x02 | Dial tone feature delay option | + +The recommended default value is 0x00. (R, W, set-by-create) (mandatory) (1 byte) + +**Direct connect URI pointer:** This attribute points to a network address ME that specifies the URI of the direct connect. If this attribute is set to a null pointer, no URI is defined. (R, W, set-by-create) (mandatory) (2 bytes) + +**Bridged line agent URI pointer:** This attribute points to a network address ME that specifies the URI of the bridged line agent. If this attribute is set to a null pointer, no URI is defined. (R, W, set-by-create) (mandatory) (2 bytes) + +**Conference factory URI pointer:** This attribute points to a network address ME that specifies the URI of the conference factory. If this attribute is set to a null pointer, no URI is defined. (R, W, set-by-create) (mandatory) (2 bytes) + +**Dial tone feature delay/warmline timer (new):** This attribute defines the warmline timer/dial tone feature delay timer (seconds). The default value 0 specifies vendor-specific implementation. (R, W) (optional) (2 bytes) + +**IP host pointer:** This attribute points to the IP host config data or IPv6 host config data ME associated with this VoIP config data ME. This attribute is only relevant when the VoIP configuration method used attribute of this ME is set to configuration file retrieval (2) OR IETF sipping config framework (4). Upon instantiation ONU sets this value to NULL (0xFFFF) pointer. (R, W) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.9.9 VoIP feature access codes** + +The VoIP feature access codes ME defines administrable feature access codes for the VoIP subscriber. It is optional for ONUs that support VoIP services. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. + +Instances of this ME are created and deleted by the OLT. A VoIP feature access codes instance is needed for each unique set of feature access code attributes. + +#### *Relationships* + +An instance of this ME may be associated with one or more SIP user data MEs. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R) (mandatory) (2 bytes) + +The remaining attributes are access codes for the features mentioned in their names. Each attribute is a string of characters from the set {0..9, \*, #}, with trailing nulls in any unused bytes. + +| | | +|----------------------------------------|-----------------------------| +| Cancel call waiting: | (R, W) (optional) (5 bytes) | +| Call hold: | (R, W) (optional) (5 bytes) | +| Call park: | (R, W) (optional) (5 bytes) | +| Caller ID activate: | (R, W) (optional) (5 bytes) | +| Caller ID deactivate: | (R, W) (optional) (5 bytes) | +| Do not disturb activation: | (R, W) (optional) (5 bytes) | +| Do not disturb deactivation: | (R, W) (optional) (5 bytes) | +| Do not disturb PIN change: | (R, W) (optional) (5 bytes) | +| Emergency service number: | (R, W) (optional) (5 bytes) | +| Intercom service: | (R, W) (optional) (5 bytes) | +| Unattended/blind call transfer: | (R, W) (optional) (5 bytes) | +| Attended call transfer: | (R, W) (optional) (5 bytes) | + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.9.10 Network dial plan table + +The network dial plan table ME is optional for ONUs providing VoIP services. This ME is used to provision dial plans from the OLT. Instances of this ME are created and deleted by the OLT. If a non-OMCI interface is used to manage SIP for VoIP, this ME is unnecessary. + +#### *Relationships* + +An instance of this ME may be associated with one or more instances of the SIP user data ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Dial plan number:** This attribute indicates the current number of dial plans in the dial plan table. (R) (mandatory) (2 bytes) + +**Dial plan table max size:** This attribute defines the maximum number of dial plans that can be stored in the dial plan table. (R, set-by-create) (mandatory) (2 bytes) + +**Critical dial timeout:** This attribute defines the critical dial timeout for digit map processing, in milliseconds. The recommended default value is 4000 ms. (R, W, set-by-create) (mandatory) (2 bytes) + +**Partial dial timeout:** This attribute defines the partial dial timeout for digit map processing, in milliseconds. The recommended default value is 16000 ms. (R, W, set-by-create) (mandatory) (2 bytes) + +**Dial plan format:** This attribute defines the dial plan format standard that is supported in the ONU for VoIP. Valid values include the following. + +- 0 Not defined +- 1 ITU-T H.248 format with a specific plan (table entries define the dialling plan) +- 2 NCS format [b-PKT-SP-NCS ] +- 3 Vendor-specific format + +(R, W, set-by-create) (mandatory) (1 byte) + +**Dial plan table:** The table is the digit map that describes the dial plans used by the VoIP service, along with fields to manage the table. An example digit map is the string, + +(0T|00T|[1-7]xxx|8xxxxxxx|#xxxxxxx|\*xx|91xxxxxxxxxx|9011x.T) + +Each row of the table comprises the following fields: + +**Dial plan ID:** The row number, a unique identifier of a dial plan within the dial plan table (1 byte). + +**Action:** Remove (0) or add (1) this plan (set action). When a dial plan is being removed, the dial plan token field is not used. (1 byte). + +**Dial plan token:** The definition of the dial plan itself. In the previous example, tokens include the strings "0T" and "\*xx". Unused trailing bytes may be padded with nulls or ASCII spaces. (28 bytes) + +NOTE – Due to previously ambiguous documentation, implementations may vary. For interoperability, the OLT should write table entries as documented above, while it is encouraged for the ONU to accept any characters outside the formal grammar as delimiters and to accept the concatenation of rows as a single string that defines a digit map. + +(R, W) (mandatory) (30 \* *N* bytes, where *N* is the number of dial plans) + +#### *Actions* + +Create, delete, get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.9.11 VoIP line status** + +The VoIP line status ME contains line status information for POTS ports using VoIP services. An ONU that supports VoIP automatically creates or deletes an instance of this ME upon creation or deletion of a PTP POTS UNI. + +#### *Relationships* + +An instance of this ME is associated with a PTP POTS UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PTP POTS UNI. (R) (mandatory) (2 bytes) + +**Voip codec used:** Reports the current codec used for a VoIP POTS port. Valid values are taken from [IETF RFC 3551], and are the same as specified in the codec selection attribute of the VoIP media profile. This attribute is meaningful only if the VoIP port session type attribute is not idle. + +- 0 PCMU +- 1 reserved +- 2 reserved +- 3 GSM +- 4 ITU-T G.723 +- 5 DVI4, 8 kHz +- 6 DVI4, 16 kHz +- 7 LPC +- 8 PCMA +- 9 ITU-T G.722 +- 10 L16, 2 channels +- 11 L16, 1 channel +- 12 QCELP +- 13 CN +- 14 MPA +- 15 ITU-T G.728 +- 16 DVI4, 11.025 kHz +- 17 DVI4, 22.050 kHz +- 18 ITU-T G.729 + +(R) (mandatory) (2 bytes) + +**Voip voice server status:** Status of the VoIP session for this POTS port: + +- 0 None/initial +- 1 Registered +- 2 In session +- 3 Failed registration – icmp error +- 4 Failed registration – failed tcp +- 5 Failed registration – failed authentication + +- 6 Failed registration – timeout +- 7 Failed registration – server fail code +- 8 Failed invite – icmp error +- 9 Failed invite – failed tcp +- 10 Failed invite – failed authentication +- 11 Failed invite – timeout +- 12 Failed invite – server fail code +- 13 Port not configured +- 14 Config done +- 15 Disabled by switch + +(R) (mandatory) (1 byte) + +**Voip port session type:** This attribute reports the current state of a VoIP POTS port session: + +- 0 Idle/none +- 1 2way +- 2 3way +- 3 Fax/modem +- 4 Telemetry +- 5 Conference + +(R) (mandatory) (1 byte) + +**Voip call 1 packet period:** This attribute reports the packet period for the first call on the VoIP POTS port. The value is defined in milliseconds. (R) (mandatory) (2 bytes) + +**Voip call 2 packet period:** This attribute reports the packet period for the second call on the VoIP POTS port. The value is defined in milliseconds. (R) (mandatory) (2 bytes) + +**Voip call 1 dest addr:** This attribute reports the DA for the first call on the VoIP POTS port. The value is an ASCII string. (R) (mandatory) (25 bytes) + +**Voip call 2 dest addr:** This attribute reports the DA for the second call on the VoIP POTS port. The value is an ASCII string. (R) (mandatory) (25 bytes) + +**Voip line state:** This attribute reports the state of the POTS line. This attribute may not be meaningful if the POTS port is administratively locked, is operationally disabled, or is being tested. Code points are assigned as follows: + +- 0 Idle, on-hook +- 1 Off-hook dial tone +- 2 Dialling +- 3 Ringing or FSK alerting/data +- 4 Audible ringback +- 5 Connecting +- 6 Connected +- 7 Disconnecting, audible indication +- 8 ROH, no tone +- 9 ROH with tone +- 10 Unknown or undefined + +(R) (optional) (1 byte) + +**Emergency call status:** This attribute reports the current state of an emergency call session (when the ONU is the call originator) on the VoIP POTS port. The ONU determines the presence of an originating emergency call on the basis of the Emergency service number attribute of the VoIP feature access codes ME. + +- 0 No emergency call in progress + +##### 1 Emergency call in progress + +NOTE – The ONU may also be able to determine the presence of an emergency call on the basis of other, unspecified information. + +(R) (Optional) (1 byte) + +#### *Actions* + +Get + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|------------------------------------------------------------| +| 1..8 | N/A | | +| 9 | Emergency call status | Indicates an update to the Emergency call status attribute | +| 10..16 | Reserved | | + +### **9.9.12 Call control performance monitoring history data** + +This ME collects PM data related to the call control channel. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the PPTP POTS UNI ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP POTS UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Call setup failures:** This attribute counts call set-up failures. (R) (mandatory) (4 bytes) + +**Call setup timer:** This attribute is a high water-mark that records the longest duration of a single call set-up detected during this interval. Time is measured in milliseconds from the time an initial set-up was requested by the subscriber until the time at which a response was provided to the subscriber in the form of busy tone, audible ring tone, etc. (R) (mandatory) (4 bytes) + +**Call terminate failures:** This attribute counts the number of calls that were terminated with cause. (R) (mandatory) (4 bytes) + +**Analog port releases:** This attribute counts the number of analogue port releases without dialling detected (abandoned calls). (R) (mandatory) (4 bytes) + +**Analog port off-hook timer:** This attribute is a high water-mark that records the longest period of a single off-hook detected on the analogue port. Time is measured in milliseconds. (R) (mandatory) (4 bytes) + +#### Actions + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|------------------------------------|--------------------------------------| +| 0 | CCPM call set-up fail | 1 | +| 1 | CCPM set-up timeout | 2 | +| 2 | CCPM call terminate | 3 | +| 3 | CCPM port release with no dialling | 4 | +| 4 | CCPM port offhook timeout | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.9.13 RTP performance monitoring history data + +This ME collects PM data related to an RTP session. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of the PPTP POTS UNI ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP POTS UNI ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**RTP errors:** This attribute counts RTP packet errors. (R) (mandatory) (4 bytes) + +**Packet loss:** This attribute represents the fraction of packets lost. This attribute is calculated at the end of the 15 min interval, and is undefined under the get current data action. The value 0 indicates no packet loss, scaling linearly to 0xFFFF FFFF to indicate 100% packet loss (zero divided by zero is defined to be zero). (R) (mandatory) (4 bytes) + +**Maximum jitter:** This attribute is a high water-mark that represents the maximum jitter identified during the measured interval, expressed in RTP timestamp units. (R) (mandatory) (4 bytes) + +**Maximum time between real-time transport control protocol (RTCP) packets:** This attribute is a high water-mark that represents the maximum time between + +RTCP packets during the measured interval, in milliseconds. (R) (mandatory) (4 bytes) + +**Buffer underflows:** This attribute counts the number of times the reassembly buffer underflows. In the case of continuous underflow caused by a loss of IP packets, a single buffer underflow should be counted. If the IW function is implemented with multiple buffers, such as a packet level buffer and a bit level buffer, then the underflow of either buffer increments this counter. (R) (mandatory) (4 bytes) + +**Buffer overflows:** This attribute counts the number of times the reassembly buffer overflows. If the IW function is implemented with multiple buffers, such as a packet level buffer and a bit level buffer, then the overflow of either buffer increments this counter. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note 2) | +|--------------|-------------------------------|----------------------------------------| +| 0 | RTP errors | 1 | +| 1 | Packet loss(Note 1) | 2 | +| 2 | Maximum jitter | 3 | +| 3 | Max time between RTCP packets | 4 | +| 4 | Buffer underflows | 6 | +| 5 | Buffer overflows | 7 | + +NOTE 1 – Since packet loss is undefined until the end of the interval, this TCA may only be issued at the interval boundary, whereupon it is then immediately cleared. + +NOTE 2 – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.9.14 SIP agent performance monitoring history data** + +This ME collects PM data for the associated VoIP SIP agent. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with a SIP agent config data or SIP config portal object. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the corresponding SIP agent config data or to the SIP config portal. If a non-OMCI configuration method is used for VoIP, there can be only one live ME instance, associated with the SIP config portal, and with ME ID 0. (R, set-by-create) (mandatory) (2 bytes) + +- Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) +- Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) +- Transactions:** This attribute counts the number of new transactions that were initiated. (R) (optional) (4 bytes) +- Rx invite reqs:** This attribute counts received invite messages, including retransmissions. (R) (optional) (4 bytes) +- Rx invite retrans:** This attribute counts received invite retransmission messages. (R) (optional) (4 bytes) +- Rx noninvite reqs:** This attribute counts received non-invite messages, including retransmissions. (R) (optional) (4 bytes) +- Rx noninvite retrans:** This attribute counts received non-invite retransmission messages. (R) (optional) (4 bytes) +- Rx response:** This attribute counts total responses received. (R) (optional) (4 bytes) +- Rx response retransmissions:** This attribute counts total response retransmissions received. (R) (optional) (4 bytes) +- Tx invite reqs:** This attribute counts transmitted invite messages, including retransmissions. (R) (optional) (4 bytes) +- Tx invite retrans:** This attribute counts transmitted invite retransmission messages. (R) (optional) (4 bytes) +- Tx noninvite reqs:** This attribute counts transmitted non-invite messages, including retransmissions. (R) (optional) (4 bytes) +- Tx noninvite retrans:** This attribute counts transmitted non-invite retransmission messages. (R) (optional) (4 bytes) +- Tx response:** This attribute counts the total responses sent. (R) (optional) (4 bytes) +- Tx response retransmissions:** This attribute counts total response retransmissions sent. (R) (optional) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|----------------------------------------|--------------------------------------| +| 0 | SIPAMD Rx invite req | 1 | +| 1 | SIPAMD Rx invite req retransmission | 2 | +| 2 | SIPAMD Rx noninvite req | 3 | +| 3 | SIPAMD Rx noninvite req retransmission | 4 | + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-----------------------------------|--------------------------------------| +| 4 | SIPAMD Rx response | 5 | +| 5 | SIPAMD Rx response retransmission | 6 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.9.15 SIP call initiation performance monitoring history data + +This ME collects PM data related to call initiations of a VoIP SIP agent. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of the SIP agent config data or SIP config portal ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the SIP agent config data or the SIP config portal ME. If a non-OMCI configuration method is used for VoIP, there can be only one live ME instance, associated with the SIP config portal, and with ME ID 0. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Failed to connect counter:** This attribute counts the number of times that the SIP UA failed to reach/connect its TCP/UDP peer during SIP call initiations. (R) (mandatory) (4 bytes) + +**Failed to validate counter:** This attribute counts the number of times that the SIP UA failed to validate its peer during SIP call initiations. (R) (mandatory) (4 bytes) + +**Timeout counter:** This attribute counts the number of times that the SIP UA timed out during SIP call initiations. (R) (mandatory) (4 bytes) + +**Failure received counter:** This attribute counts the number of times that the SIP UA received a failure error code during SIP call initiations. (R) (mandatory) (4 bytes) + +**Failed to authenticate counter:** This attribute counts the number of times that the SIP UA failed to authenticate itself during SIP call initiations. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-----------------------------------------|--------------------------------------| +| 0 | SIP call PM failed connect | 1 | +| 1 | SIP call PM failed to validate | 2 | +| 2 | SIP call PM timeout | 3 | +| 3 | SIP call PM failure error code received | 4 | +| 4 | SIP call PM failed to authenticate | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.9.16 MGC config data + +The MGC config data ME defines the MGC configuration associated with an MG subscriber. It is conditionally required for ONUs that support ITU-T H.248 VoIP services. If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. + +Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME may be associated with one or more VoIP voice CTP MEs. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Primary MGC:** This attribute points to a network address ME that contains the name (IP address or resolved name) of the primary MGC that controls the signalling messages. The port is optional and defaults to 2944 for text message formats and 2955 for binary message formats. (R, W, set-by-create) (mandatory) (2 bytes) + +**Secondary MGC:** This attribute points to a network address ME that contains the name (IP address or resolved name) of the secondary or backup MGC that controls the signalling messages. The port is optional and defaults to 2944 for text message formats and 2955 for binary message formats. (R, W, set-by-create) (mandatory) (2 bytes) + +**TCP/UDP pointer:** This attribute points to the TCP/UDP config data ME to be used for communication with the MGC. (R, W, set-by-create) (mandatory) (2 bytes) + +**Version:** This integer attribute reports the version of the Megaco protocol in use. The ONU should deny an attempt by the OLT to set or create a value that it does not support. The value 0 indicates that no particular version is specified. (R, W, set-by-create) (mandatory) (1 byte) + +**Message format:** This attribute defines the message format. Valid values are as follows. + +- 0 Text long +- 1 Text short +- 2 Binary + +The default value is recommended to be 0. (R, W, set-by-create) (mandatory) (1 byte) + +- Maximum retry time:** This attribute specifies the maximum retry time for MGC transactions, in seconds. The default value 0 specifies vendor-specific implementation. (R, W) (optional) (2 bytes) +- Maximum retry attempts:** This attribute specifies the maximum number of times a message is retransmitted to the MGC. The recommended default value 0 specifies vendor-specific implementation. (R, W, set-by-create) (optional) (2 bytes) +- Service change delay:** This attribute specifies the service status delay time for changes in line service status. This attribute is specified in seconds. The default value 0 specifies no delay. (R, W) (optional) (2 bytes) +- Termination ID base:** This attribute specifies the base string for the ITU-T H.248 physical termination ID(s) for this ONU. This string is intended to uniquely identify an ONU. Vendor-specific termination identifiers (port IDs) are optionally added to this string to uniquely identify a termination on a specific ONU. (R, W) (optional) (25 bytes) +- Softswitch:** This attribute identifies the gateway softswitch vendor. The format is four ASCII coded alphabetic characters [A..Z] as defined in [ATIS-0300220]. A value of four null bytes indicates an unknown or unspecified vendor. (R, W, set-by-create) (mandatory) (4 bytes) +- Message ID pointer:** This attribute points to a large string whose value specifies the message identifier string for ITU-T H.248 messages originated by the ONU. (R, W, set-by-create) (optional) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|------------------------|--------------------------------| +| 0 | Timeout | Timeout of association with MG | +| 1..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.9.17 MGC performance monitoring history data** + +The MGC monitoring data ME provides run-time statistics for an active MGC association. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of the MGC config data or MGC config portal ME. + +#### *Attributes* + +- Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the associated MGC config data or to the MGC config portal ME. If a non-OMCI configuration method is used for VoIP, there can be only one live ME instance, associated + +with the MGC config portal, and with ME ID 0. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Received messages:** This attribute counts the number of received Megaco messages on this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) + +**Received octets:** This attribute counts the total number of octets received on this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) + +**Sent messages:** This attribute counts the total number of Megaco messages sent over this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) + +**Sent octets:** This attribute counts the total number of octets sent over this association, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) + +**Protocol errors:** This attribute counts the total number of errors detected on this association, as defined by [ITU-T H.341]. This includes: + +- syntax errors detected in a given received message; +- outgoing transactions that failed for protocol reasons. + +(R) (mandatory) (4 bytes) + +**Transport losses:** This attribute counts the total number of transport losses (e.g., socket problems) detected on this association. A link loss is defined as loss of communication with the remote entity due to hardware/transient problems, or problems in related software. (R) (mandatory) (4 bytes) + +**Last detected event:** This attribute reports the last event detected on this association. This includes events such as the link failing or being set up. Under normal circumstances, a get action on this attribute would return 0 to indicate no abnormal activity. This field is an enumeration as follows. + +- 0 No event – No event has yet been detected during this PM interval. +- 1 Link up – The transport link underpinning the association came up. +- 2 Link down – The transport link underpinning the association went down. +- 3 Persistent error – A persistent error was detected on the link (such as the socket/TCP connection to the remote node could not be set up). +- 4 Local shutdown – The association was brought down intentionally by the local application. +- 5 Failover down – The association was brought down as part of failover processing. +- 255 Other event – The latest event does not match any in the list. + +(R) (mandatory) (1 byte) + +**Last detected event time:** This attribute reports the time in seconds since the last event on this association was detected, as defined by [ITU-T H.341]. (R) (mandatory) (4 bytes) + +**Last detected reset time:** This attribute reports the time in seconds since these statistics were last reset, as defined by [ITU-T H.341]. Under normal circumstances, a get + +action on this attribute would return 900 s to indicate a completed 15 min interval. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | MGCP protocol errors | 1 | +| 1 | MGCP transport losses | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.9.18 VoIP config data + +The VoIP configuration data ME defines the configuration for VoIP in the ONU. The OLT uses this ME to discover the VoIP signalling protocols and configuration methods supported by this ONU. The OLT then uses this ME to select the desired signalling protocol and configuration method. The entity is conditionally required for ONUs that offer VoIP services. + +An ONU that supports VoIP services automatically creates an instance of this ME. + +#### Relationships + +One instance of this ME is associated with the ONU. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Available signalling protocols:** This attribute is a bit map that defines the VoIP signalling protocols supported in the ONU. The bit value 1 specifies that the ONU supports the associated protocol. + +- | | | | +|---|-------|-------------| +| 1 | (LSB) | SIP | +| 2 | | ITU-T H.248 | +| 3 | | MGCP | + +(R) (mandatory) (1 byte) + +**Signalling protocol used:** This attribute specifies the VoIP signalling protocol to use. Only one type of protocol is allowed at a time. Valid values are: + +- | | | +|------|-------------------------------------------| +| 0 | None | +| 1 | SIP | +| 2 | ITU-T H.248 | +| 3 | MGCP | +| 0xFF | Selected by non-OMCI management interface | + +(R, W) (mandatory) (1 byte) + +**Available VoIP configuration methods:** This attribute is a bit map that indicates the capabilities of the ONU with regard to VoIP service configuration. The bit value 1 specifies that the ONU supports the associated capability. + +- 1 (LSB) ONU capable of using the OMCI to configure its VoIP services. +- 2 ONU capable of working with configuration file retrieval to configure its VoIP services. +- 3 ONU capable of working with [BBF TR-069] to configure its VoIP services. +- 4 ONU capable of working with IETF sipping config framework to configure its VoIP services. +- 5 ONU capable of working with [BBF TR-369] to configure its VoIP services. + +Bits 6..24 are reserved by ITU-T. Bits 25..32 are reserved for proprietary vendor configuration capabilities. (R) (mandatory) (4 bytes) + +**VoIP configuration method used:** Specifies which method is used to configure the ONU's VoIP service. + +- 0 Do not configure – ONU default +- 1 OMCI +- 2 Configuration file retrieval +- 3 BBF TR-069 +- 4 IETF sipping config framework +- 5 BBF TR-369 +- 6..240 Reserved by ITU-T +- 241..255 Reserved for proprietary vendor configuration methods + +(R, W) (mandatory) (1 byte) + +**VoIP configuration address pointer:** If this attribute is set to any value other than a null pointer, it points to a network address ME, which indicates the address of the server to contact using the method indicated in the VoIP configuration method used attribute. This attribute is only relevant for non-OMCI configuration methods. + +If this attribute is set to a null pointer, no address is defined by this attribute. However, the address may be defined by other methods, such as deriving it from the ONU identifier attribute of the IP host config data ME and using a well-known URI schema. + +The default value is 0xFFFF (R, W) (mandatory) (2 bytes) + +**VoIP configuration state:** Indicates the status of the ONU VoIP service. + +- 0 Inactive: configuration retrieval has not been attempted +- 1 Active: configuration was retrieved +- 2 Initializing: configuration is now being retrieved +- 3 Fault: configuration retrieval process failed + +Other values are reserved. At ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (1 byte) + +**Retrieve profile:** This attribute provides a means by which the ONU may be notified that a new VoIP profile should be retrieved. By setting this attribute, the OLT triggers the ONU to retrieve a new profile. The actual value in the set action is ignored because it is the action of setting that is important. (W) (mandatory) (1 byte) + +**Profile version:** This attribute is a character string that identifies the version of the last retrieved profile. (R) (mandatory) (25 bytes) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-----------------------------------| +| 1..7 | N/A | | +| 8 | Profile version | Version of last retrieved profile | +| 9..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|----------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | VCD config server name | Failed to resolve the configuration server name. | +| 1 | VCD config server reach | Cannot reach configuration server (the port cannot be reached, ICMP errors) | +| 2 | VCD config server connect | Cannot connect to the configuration server (due to bad credentials or other faults after the port has responded) | +| 3 | VCD config server validate | Cannot validate the configuration server | +| 4 | VCD config server auth | Cannot authenticate the configuration session (e.g., missing credentials) | +| 5 | VCD config server timeout | Timeout waiting for response from configuration server | +| 6 | VCD config server fail | Failure response received from configuration server | +| 7 | VCD config file error | Configuration file received has an error | +| 8 | VCD subscription name | Failed to resolve the subscription server name | +| 9 | VCD subscription reach | Cannot reach subscription server (the port cannot be reached, ICMP errors) | +| 10 | VCD subscription connect | Cannot connect to subscription server (due to bad credentials or other faults after the port has responded) | +| 11 | VCD subscription validate | Cannot validate subscription server | +| 12 | VCD subscription auth | Cannot authenticate subscription session (e.g., missing credentials) | +| 13 | VCD subscription timeout | Timeout waiting for response from subscription server | +| 14 | VCD subscription fail | Failure response received from subscription server | +| 15 | VCD reboot request | A non-OMCI management interface has requested a reboot of the ONU.
NOTE – This alarm is used only to indicate the request and not to indicate that a reboot has actually taken place. | +| 16 | VCD Notify timeout | Failure to receive the NOTIFY that the server is required to send following acceptance of a SUBSCRIBE request. | +| 17 | VCD Notify malformed | Malformed NOTIFY request | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 18 | VCD Notify Rejected | NOTIFY request specifies that the subscription is terminated because it has been rejected by the server or the server has no resources to accept it (this may be received following a SUBSCRIBE to which the server returned a 202 (Accepted) response) | +| 19..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.9.19 SIP config portal + +The SIP config portal ME provides a way for the OLT to discover the configuration text delivered to an ONU by a non-OMCI SIP VoIP configuration method ([BBF TR-069]/[BBF TR-369], sipping framework, etc.). Text retrieved from this ME is not required to be understood by the OLT or EMS, but it may be useful for human or vendor-specific analysis tools. See also the MGC config portal ME. + +An instance of this ME may be created by an ONU that supports non-OMCI SIP configuration. It is not reported during an MIB upload. + +#### Relationships + +One instance of this ME is associated with the ONU. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is one instance, number 0. (R) (mandatory) (2 bytes) + +**Configuration text table:** This attribute is used to pass a textual representation of the VoIP configuration back to the OLT. The contents are vendor-specific. The get, get next sequence must be used with this attribute since its size is unspecified. Upon ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (*x* bytes) + +#### Actions + +Get, get next + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Configuration text | Indicates an update to the VoIP configuration from a non-OMCI interface. Because the attribute is a table, the AVC does not contain information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 2..16 | Reserved | | + +### 9.9.20 MGC config portal + +The MGC config portal ME provides a way for the OLT to discover the configuration text delivered to an ONU by a non-OMCI ITU-T H.248 VoIP configuration method. Text retrieved from this ME is not required to be understood by the OLT or EMS, but it may be useful for human or vendor-specific analysis tools. See also the SIP config portal ME. + +An instance of this ME may be created by an ONU that supports non-OMCI ITU-T H.248 configuration. It is not reported during an MIB upload. + +#### *Relationships* + +One instance of this ME is associated with the ONU. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is one instance, number 0. (R, set-by-create) (mandatory) (2 bytes) + +**Configuration text table:** This attribute is used to pass a textual representation of the VoIP configuration back to the OLT. The contents are vendor-specific. The get, get next sequence must be used with this attribute since its size is unspecified. Upon ME instantiation, the ONU sets this attribute to 0. (R) (mandatory) (x bytes) + +#### *Actions* + +Get, get next + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Configuration text | Indicates an update to the VoIP configuration from a non-OMCI interface. Because the attribute is a table, the AVC does not contain information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 2..16 | Reserved | | + +### 9.9.21 SIP agent config data 2 + +This ME supplements SIP agent config data ME. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with a SIP agent config data. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the corresponding SIP agent config data. Note that this entity is associated with the primary SIP agent config data (if SIP agent is involved in protection). (R, set-by-create) (mandatory) (2 bytes) + +- In-Use-Options-Timer:** This attribute defines the frequency that a SIP options packet is sent to the SIP proxy in-use. When a SIP options packet is not responded to by the SIP proxy, it is marked as unavailable. Otherwise, it is marked as available. Units are seconds. The default value 0 specifies vendor-specific implementation. (R, W, set-by-create) (mandatory) (2 byte) +- Alternate-Options-Timer:** This attribute defines the frequency that a SIP options packet is sent to the standby SIP proxy. When a SIP options packet is not responded to by the standby SIP proxy, it is marked as unavailable. Otherwise, it is marked as available. Units are seconds. The default value 0 specifies vendor-specific implementation. (R, W, set-by-create) (mandatory) (2 byte) +- Revertive:** This Boolean attribute specifies whether the SIP UA is involved in revertive (true) or non-revertive (false) switching. The default value is recommended to be false. (R, W, set-by-create) (mandatory) (1 byte) +- Current proxy server resolved address:** This attribute contains the resolved IP address of the in-use SIP proxy. If the value is 0.0.x.y, where *x* and *y* are not both 0, then *x.y* is to be interpreted as a pointer to a large string ME that represents an IPv6 address. Otherwise, the address is an IPv4 address (R) (optional) (4 bytes) +- Current proxy server resolved name:** This attribute contains a pointer to the large string ME that contains the resolved name of the SIP proxy in-use. (R) (optional) (2 bytes) +- Alternate proxy server resolved address:** This attribute contains the resolved IP address of the alternate SIP proxy. If the value is 0.0.x.y, where *x* and *y* are not both 0, then *x.y* is to be interpreted as a pointer to a large string ME that represents an IPv6 address. Otherwise, the address is an IPv4 address (R) (optional) (4 bytes) +- Alternate proxy server resolved name:** This attribute contains a pointer to the large string ME that contains the resolved name of the alternate SIP proxy. (R) (optional) (2 bytes) + +#### Actions + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +- None + +## 9.10 Premises networks + +This clause defines MEs associated with home networking UNIs, as shown in Figure 9.10-1. + +![Diagram showing the PPTP MoCA UNI (9.10.1) pointed to by 802.1p mapper service profile and (Extended)VLAN tagging operation config data. The PPTP MoCA UNI is also connected to MoCA Ethernet PM history data (9.10.2) and MoCA interface PM history data (9.10.3).](0094a2894b7be18f168c89acdae69a2b_img.jpg) + +``` + +graph LR + A["802.1p mapper service profile +(Extended)VLAN tagging operation config data"] -- "Pointed to by:" --> B["PPTP MoCA UNI +9.10.1"] + B -.-> C["MoCA Ethernet PM history data +9.10.2"] + B -.-> D["MoCA interface PM history data +9.10.3"] + +``` + +G.988(12)\_F9.10-1 + +Diagram showing the PPTP MoCA UNI (9.10.1) pointed to by 802.1p mapper service profile and (Extended)VLAN tagging operation config data. The PPTP MoCA UNI is also connected to MoCA Ethernet PM history data (9.10.2) and MoCA interface PM history data (9.10.3). + +**Figure 9.10-1 – Managed entities associated with home networking** + +### 9.10.1 Physical path termination point MoCA UNI + +This ME represents an MoCA UNI, where physical paths terminate and physical path level functions are performed. + +The ONU automatically creates an instance of this ME per port as follows. + +- When the ONU has MoCA ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the MoCA type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the MoCA type. Note that the installation of a plug-and-play card may indicate the presence of MoCA ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies MoCA ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect an MoCA circuit pack, nor is it equipped with an MoCA circuit pack. + +#### Relationships + +An instance of this ME is associated with each real or pre-provisioned MoCA port. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number is directly associated with the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +**Loopback configuration:** This attribute sets the MoCA loopback configuration. Note that normal bridge behaviour may defeat the loopback signal unless broadcast MAC addresses are used. + +- 0 No loopback +- 3 Loopback3, loopback of downstream traffic after PHY transceiver, depicted in Figure 9.10.1-1. + +Upon ME instantiation, the ONU sets this attribute to 0. (R, W) (optional) (1 byte) + +![Diagram of MoCA loopback configuration showing an ONU with a PHY transceiver. The MoCA UNI is connected to the PHY transceiver. A loopback path is shown from the PHY transceiver back to itself, labeled 'Loopback 3'. The PHY transceiver is also connected to a PON (Passive Optical Network) port.](31609508ec41c58e37f09c9df3fc209b_img.jpg) + +The diagram illustrates the internal architecture of an ONU for MoCA loopback. On the left, the 'MoCA UNI' is connected to a 'PHY transceiver' block. Inside the 'PHY transceiver', there is a curved arrow labeled 'Loopback 3' that loops from the output back to the input. The 'PHY transceiver' is connected to an 'ONU' block, which in turn is connected to a 'PON' (Passive Optical Network) port on the right. The diagram is labeled 'G.988(12)\_F9.10.1-1' at the bottom right. + +Diagram of MoCA loopback configuration showing an ONU with a PHY transceiver. The MoCA UNI is connected to the PHY transceiver. A loopback path is shown from the PHY transceiver back to itself, labeled 'Loopback 3'. The PHY transceiver is also connected to a PON (Passive Optical Network) port. + +Figure 9.10.1-1 – MoCA loopback configuration + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Max frame size:** This attribute denotes the maximum frame size allowed across this interface. Upon ME instantiation, the ONU sets this attribute to 1518. (R, W) (mandatory) (2 bytes) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**PPPoE filter:** This attribute controls filtering of PPPoE packets on this MoCA port. When its value is 1, all packets other than PPPoE packets are discarded. The default 0 accepts packets of all types. (R, W) (optional) (1 byte) + +**Network status:** This attribute indicates the networking state of the MoCA interface as follows. + +- 0 The interface has not joined an MoCA network. +- 1 The interface has joined an MoCA network. +- 2 The interface has joined an MoCA network and is currently the network coordinator. + +(R) (mandatory) (1 byte) + +**Password:** This attribute specifies the MoCA encryption key. It is an ASCII string of 17 decimal digits. Upon ME instantiation, the ONU sets this attribute to 17 null bytes. (R, W) (mandatory) (17 bytes) + +**Privacy enabled:** This attribute activates (1) link-layer security. The default value 0 deactivates it. (R, W) (mandatory) (1 byte) + +**Minimum bandwidth alarm threshold:** This attribute specifies the minimum desired PHY link bandwidth between two nodes. If the actual bandwidth is lower, an LL alarm is declared. Valid values are 0 to 0x0410 (260 Mbit/s) in 0.25 Mbit/s increments. The default value is 0x02D0 (180 Mbit/s). The value 0 disables the threshold. (R, W) (optional) (2 bytes) + +**Frequency mask:** This attribute is a bit map of the centre frequencies that the interface is permitted to use, where each bit represents a centre frequency. The LSB (*b*[1]) corresponds to centre frequency 800 MHz. The next significant bit (*b*[2]) corresponds to centre frequency 825 MHz. The 28th bit (*b*[28]) corresponds to centre frequency 1500 MHz. The four MSBs are not used. (R, W) (optional) (4 bytes) + +**RF channel:** This attribute reports the frequency to which the MoCA interface is currently tuned, in megahertz. (R) (mandatory) (2 bytes) + +**Last operational frequency:** This attribute reports the frequency to which the MoCA interface was tuned when last operational, in megahertz. (R) (mandatory) (2 bytes) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------| +| 1..2 | N/A | | +| 3 | Op state | Operational state | +| 4 | N/A | | +| 5 | ARC | ARC timer expiration | +| 6..14 | N/A | | +| 15..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|------------------------------------------------------------------------------------------| +| 0 | MoCA LOL | Loss of link at the MoCA interface | +| 1 | MoCA limited link (LL) | Bandwidth of link between two nodes on the MoCA network is less than the specified value | +| 2..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.10.2 MoCA Ethernet performance monitoring history data + +This ME collects PM data for an MoCA Ethernet interface. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of the PPTP MoCA UNI ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP MoCA UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +Incoming PM refers to upstream traffic received on the UNI; outgoing PM refers to downstream traffic transmitted on the UNI. + +**Incoming unicast packets:** (R) (optional) (4 bytes) + +**Incoming discarded packets:** (R) (optional) (4 bytes) + +**Incoming errored packets:** (R) (optional) (4 bytes) + +**Incoming unknown packets:** (R) (optional) (4 bytes) + +**Incoming multicast packets:** (R) (optional) (4 bytes) + +**Incoming broadcast packets:** (R) (optional) (4 bytes) + +**Incoming octets:** (R) (optional) (4 bytes) + +**Outgoing unicast packets:** (R) (optional) (4 bytes) + +**Outgoing discarded packets:** (R) (optional) (4 bytes) + +**Outgoing errored packets:** (R) (optional) (4 bytes) + +**Outgoing unknown packets:** (R) (optional) (4 bytes) + +**Outgoing multicast packets:** (R) (optional) (4 bytes) + +**Outgoing broadcast packets:** (R) (optional) (4 bytes) + +**Outgoing octets:** (R) (optional) (4 bytes) + +#### Actions + +Create, delete, get, set + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|----------------------------|--------------------------------------| +| 0 | Incoming unicast packets | 1 | +| 1 | Incoming discarded packets | 2 | +| 2 | Incoming errored packets | 3 | +| 3 | Incoming unknown packets | 4 | +| 4 | Incoming multicast packets | 5 | +| 5 | Incoming broadcast packets | 6 | +| 6 | Incoming octets | 7 | +| 7 | Outgoing unicast packets | 8 | +| 8 | Outgoing discarded packets | 9 | +| 9 | Outgoing errored packets | 10 | +| 10 | Outgoing unknown packets | 11 | +| 11 | Outgoing multicast packets | 12 | +| 12 | Outgoing broadcast packets | 13 | +| 13 | Outgoing octets | 14 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.10.3 MoCA interface performance monitoring history data + +This ME collects PM data for an MoCA interface. Instances of this ME are created and deleted by the OLT. + +NOTE – The structure of this ME is an exception to the normal definition of PM MEs and normal PM behaviour (clause I.4). It should not be used as a guide for the definition of future MEs. Among other exceptions, this ME contains only current values, which are retrievable by get and get next operations; no history is retained. + +#### Relationships + +An instance of this ME is associated with an instance of the PPTP MoCA UNI ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP MoCA UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**PHY Tx broadcast rate:** This attribute indicates the MoCA PHY broadcast transmit rate from the ONU MoCA interface to all the nodes in bits per second. (R) (optional) (4 bytes) + +**Node table:** This attribute lists current nodes in the node table. The table contains MAC addresses and statistics for those nodes. These table attributes are further described in the following. Space for non-supported optional fields must be allocated in table records, and filled with zero bytes. + +**MAC address:** A unique identifier of a node within the table. (6 bytes) + +**PHY Tx rate:** MoCA PHY unicast transmit rate from the ONU MoCA interface to the node identified by the MAC address, in bits per second. (4 bytes) + +**Tx power control reduction:** The reduction in transmitter level due to power control, in decibels. Valid values range from 0 (full power) to 60. (1 byte) + +**PHY Rx rate:** MoCA PHY unicast receive rate to the ONU MoCA interface from the node identified by the MAC address, in bits per second. (optional) (4 bytes) + +**Rx power level:** The power level received at the ONU MoCA interface from the node identified by the MAC address, in decibel-milliwatts, represented as a 2s complement integer. Valid values range from +10 (0x0A) to -80 (0xB0). (1 byte) + +**PHY Rx broadcast rate:** MoCA PHY broadcast receive rate to the ONU MoCA interface from the node identified by MAC address, in bits per second. (optional) (4 bytes) + +**Rx broadcast power level:** The power level received at the ONU MoCA interface from the node identified by the MAC address, in decibel-milliwatts, represented as a 2s complement integer. Valid values range from +10 (0x0A) to -80 (0xB0). (1 byte) + +**Tx packet:** Number of packets transmitted to the node. (4 bytes) + +**Rx packet:** Number of packets received from the node. (4 bytes) + +**Rx errored and missed:** Number of errored and missed packets received from the node. The sum of this field across all entries in the node table contributes to the Rx errored and missed TCA. This field is reset to 0 on 15 min boundaries. (4 bytes) + +**Rx errored:** Number of errored packets received from the node. The sum of this field across all entries in the node table contributes to the Rx errored TCA. This field is reset to 0 on 15 min boundaries. (optional) (4 bytes) + +(R) (mandatory) $(37 * N \text{ bytes, where } N \text{ is the number of nodes in the node table})$ + +#### Actions + +Create, delete, get, get next, set + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-----------------------------|--------------------------------------| +| 0 | Total rx errored and missed | 1 | +| 1 | Total rx errored | 2 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +**9.11 This clause is intentionally left blank** + +## **9.12 General purpose managed entities** + +### **9.12.1 UNI-G** + +This ME organizes data associated with UNIs supported by GEM. One instance of the UNI-G ME exists for each UNI supported by the ONU. + +The ONU automatically creates or deletes instances of this ME upon the creation or deletion of a real or virtual circuit pack ME, one per port. + +#### *Relationships* + +An instance of the UNI-G ME exists for each instance of a PPTP ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a PPTP. (R) (mandatory) (2 bytes) + +**Deprecated:** This attribute is not used. It should be set to 0 by the OLT and ignored by the ONU. (R, W) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +NOTE – PPTP MEs also have an administrative state attribute. The user port is unlocked only if both administrative state attributes are set to unlocked. It is recommended that this attribute not be used: that the OLT set it to 0 and that the ONU ignore it. + +**Management capability:** An ONU may support the ability for some or all of its PPTPs to be managed either directly by the OMCI or from a non-OMCI management environment such as [BBF TR-069]/[BBF TR-369]. This attribute advertises the ONU's capabilities for each PPTP. + +This attribute is an enumeration with the following code points: + +- 0 OMCI only +- 1 Non-OMCI only. In this case, the PPTP may be visible to the OMCI, but only in a read-only sense, e.g., for PM collection. +- 2 Both OMCI and non-OMCI + +(R) (optional) (1 byte) + +**Non-OMCI management identifier:** If a PPTP can be managed either directly by the OMCI or a non-OMCI management environment, this attribute specifies how it is in fact to be managed. This attribute is either 0 (default = OMCI management), or it is a pointer to a VEIP, which in turn links to a non-OMCI management environment. (R, W) (optional) (2 bytes) + +**Relay agent options:** This attribute is a pointer to a large string ME whose content specifies one or more DHCP relay agent options. (R, W) (optional) (2 bytes) + +The contents of the large string are parsed by the ONU and converted into text strings. Variable substitution is based on defined three-character groups, each of which begins with the '%' character. The string '%%' is an escape mechanism whose output is a single '%' character. When the ONU cannot perform variable substitution on a substring of the large string, it generates the specified option as an exact quotation of the provisioned substring value. + +Provisioning of the large string is separate from the operation of setting the pointer in this attribute. It is the responsibility of the OLT to ensure that the large string contents are correct and meaningful. + +Three-character variable definitions are as follows. The first variable in the large string must specify one of the option types. Both options for a given IP version may be present if desired, each introduced by its option identifier. Terminology is taken from clause 3.9.3 of [b-BBF TR-101]. + +%01, %18 + +Specifies that the following string is for option 82 sub-option 1, agent circuit-ID (IPv4) or option 18, interface-ID (IPv6). The equivalence permits the same large string to be used in both IP environments. + +%02, %37 + +Specifies that the following string is for option 82 sub-option 2, relay agent remote-ID (IPv4) or option 37, relay agent remote-ID (IPv6). The equivalence permits the same large string to be used in both IP environments. + +%SL In TR-101, this is called a slot. In an ONU, this variable refers to a shelf. It is meaningful if the ONU has multiple shelves internally or is daisy-chained to multiple equipment modules. The range of this variable is "0".. "99" + +%SU In TR-101, this is called a sub-slot. In fact, it represents a cardholder. The range of this variable is "0".. "99" + +%PO UNI port number. The range of this variable is "0".. "999" + +%AE ATM or Ethernet. This variable can take on the values "atm" or "eth". + +%SV S-VID for Ethernet UNI, or ATM VPI for ATM UNI, as it exists on the DHCP request received upstream across the UNI. Range "0".. "4096" for S-VID; range "0".. "255" for VPI. The value "4096" indicates no S-VID tag. + +%CV C-VID (Q-VID) for Ethernet UNI or ATM VCI for ATM UNI, as it exists on the DHCP request received upstream across the UNI. Range "0".. "4096" for C-VID; range "0".. "65535" for VCI. The value "4096" indicates no C-VID tag. + +Spaces in the provisioned string are significant. + +Example: if the large string were provisioned with the value + +%01%SL/%SU/%PO:%AE/%SV.%CV, + +then the ONU would generate the following DHCP option 82 agent circuit-ID string for an Ethernet UNI that sent a DHCP request with no S tag and C tag = 3210 on shelf 2, slot 3, port 4. + +2/3/4:eth/4096.3210 + +With the same provisioning, the ONU would generate the following DHCP option 82 agent circuit-ID string for an ATM UNI that sent a DHCP request on VPI = 123 and VCI = 4567 on shelf 2, slot 3, port 4. + +2/3/4:atm/123.4567 + +#### Actions + +Get, set + +#### *Notifications* + +None. + +### **9.12.2 OLT-G** + +This optional ME identifies the OLT to which an ONU is connected. This ME provides a way for the ONU to configure itself for operability with a particular OLT. It also provides a way for the OLT to communicate the time of day to the ONU. + +An ONU that supports this ME automatically creates an instance of it. Immediately following the start-up phase, the OLT should set the ONU to the desired configuration. Interpretation of the OLT vendor ID, equipment ID and version attributes is a matter for negotiation between the two vendors involved. + +#### *Relationships* + +The single instance of this ME is associated with the ONU ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**OLT vendor ID:** This attribute identifies the OLT vendor. It is the same as the four most significant bytes of an ONU serial number specified in the respective TC layer specification. Upon instantiation, this attribute comprises all spaces. (R, W) (mandatory) (4 bytes) + +**Equipment ID:** This attribute may be used to identify the specific type of OLT. The default value of all spaces indicates that equipment ID information is not available or applicable to the OLT being represented. (R, W) (mandatory) (20 bytes) + +**Version:** This attribute identifies the version of the OLT as defined by the vendor. The default left-justified ASCII string "0" (padded with trailing nulls) indicates that version information is not available or applicable to the OLT being represented. (R, W) (mandatory) (14 bytes) + +**Time of day information:** This attribute provides the information required to achieve time of day synchronization between a reference clock at the OLT and a local clock at the ONU. This attribute comprises two fields: the first field (4 bytes) is the sequence number of the specified GEM superframe. The second field (10 bytes) is TstampN as defined in clause 10.4.6 of [ITU-T G.984.3], clause 13.2 of [ITU-T G.987.3] and clause 13.2 of [ITU-T G.989.3], using the timestamp format of clause 5.3.3 of [IEEE 1588]. The value 0 in all bytes is reserved as a null value. (R, W) (optional) (14 bytes) + +NOTE – In ITU-T G.987/ITU-T G.989 systems, the superframe count field of the time of day information attribute contains the 32 LSBs of the actual counter. + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### 9.12.3 Network address + +The network address ME associates a network address with security methods required to access a server. It is conditionally required for ONUs that support VoIP services. The address may take the form of a URL, a fully qualified path or IP address represented as an ASCII string. + +If a non-OMCI interface is used to manage VoIP signalling, this ME is unnecessary. + +Instances of this ME are created and deleted by the OLT or the ONU, depending on the method used and case. + +#### *Relationships* + +Any ME that requires a network address may link to an instance of this ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Instances of this ME created autonomously by the ONU have IDs in the range 0..0x7FFF. Instances created by the OLT have IDs in the range 0x8000..0xFFFE. The value 0xFFFF is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Security pointer:** This attribute points to an authentication security method ME. The authentication security method indicates the username and password to be used when retrieving the network address indicated by this ME. A null pointer indicates that security attributes are not defined for this network address. (R, W, set-by-create) (mandatory) (2 bytes) + +**Address pointer:** This attribute points to the large string ME that contains the network address. It may contain a fully qualified domain name, URI or IP address. The URI may also contain a port identifier (e.g., "x.y.z.com:5060"). A null pointer indicates that no network address is defined. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### 9.12.4 Authentication security method + +The authentication security method defines the user ID and password configuration to establish a session between a client and a server. This object may be used in the role of the client or server. An instance of this ME is created by the OLT if authenticated communication is necessary. + +#### *Relationships* + +One instance of this management entity may be associated with a network address ME. This ME may also be cited by other MEs that require authentication parameter management. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0xFFFF is reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Validation scheme:** This attribute specifies the validation scheme used when the ONU validates a challenge. Validation schemes are defined as follows. + +- 0 Validation disabled +- 1 Validate using MD5 digest authentication as defined in [IETF RFC 2617] (recommended) + +##### 3 Validate using basic authentication as defined in [IETF RFC 2617] + +(R, W) (mandatory) (1 byte) + +**Username 1:** This string attribute is the user name. If the string is shorter than 25 bytes, it must be null terminated (Note). (R, W) (mandatory) (25 bytes) + +**Password:** This string attribute is the password. If the string is shorter than 25 bytes, it must be null terminated. (R, W) (mandatory) (25 bytes) + +**Realm:** This string attribute specifies the realm used in digest authentication. If the string is shorter than 25 bytes, it must be null terminated. (R, W) (mandatory) (25 bytes) + +**Username 2:** This string attribute allows for continuation of the user name beyond 25 characters (Note). Its default value is a null string. (R, W) (optional) (25 bytes) + +NOTE – The total username is the concatenation of the username 1 and username 2 attributes if and only if: a) username 1 comprises 25 non-null characters; b) username 2 is supported by the ONU; and c) username 2 contains a leading non-null character string. Otherwise, the total username is simply the value of the username 1 attribute. + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.12.5 Large string** + +The large string ME holds character strings longer than 25 bytes, up to 375 bytes. It is maintained in up to 15 parts, each part containing 25 bytes. If the final part contains fewer than 25 bytes, it is terminated by at least one null byte. For example: + +| | | +|-----------------|----------------------------------------------| +| Number of parts | 3 | +| Part 1 | sftp://myusername:mypassw | +| Part 2 | ord@config.telecom.com:12 | +| Part 3 | 34/path/to/filename<null> | + +Or + +| | | +|-----------------|--------------------------------------------------| +| Number of parts | 3 | +| Part 1 | sftp://myusername:mypassw | +| Part 2 | ord@config.telecom.com:12 | +| Part 3 | 34/path/to/longfilename<null> | + +Instances of this ME are created and deleted by the OLT. Under some circumstances, they may also be created by the ONU. To use this ME, the OLT or ONU instantiates the large string ME and then points to the created ME from other ME instances. Systems that maintain the large string should ensure that the large string ME is not deleted while it is still linked. + +#### *Relationships* + +An instance of this ME may be cited by any ME that requires a text string longer than 25 bytes. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The value 0xFFFF is reserved. When the large string is to be used as an IPv6 address, the value 0 is also reserved. The OLT should create large string MEs starting at 1 (or 0), and numbering upwards. The ONU should create large string MEs starting at 65534 (0xFFFE) and numbering downwards. (R, set-by-create) (mandatory) (2 bytes) + +**Number of parts:** This attribute specifies the number of non-empty parts that form the large string. This attribute defaults to 0 to indicate no large string content is defined.(R, W) (mandatory) (1 byte) + +Fifteen additional attributes are defined in the following; they are identical. The large string is simply divided into as many parts as necessary, starting at part 1. If the end of the string does not lie at a part boundary, it is marked with a null byte. + +**Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11, Part 12, Part 13, Part 14, Part 15:** (R, W) (mandatory) (25 bytes \* 15 attributes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|-------------| +| 1 | Number of parts | | +| 2 | Part 1 | | +| 3 | Part 2 | | +| 4 | Part 3 | | +| 5 | Part 4 | | +| 6 | Part 5 | | +| 7 | Part 6 | | +| 8 | Part 7 | | +| 9 | Part 8 | | +| 10 | Part 9 | | +| 11 | Part 10 | | +| 12 | Part 11 | | +| 13 | Part 12 | | +| 14 | Part 13 | | +| 15 | Part 14 | | +| 16 | Part 15 | | + +NOTE – Older implementations of the OMCI may not support this notification, which has been introduced in this version of this Recommendation. + +### **9.12.6 Threshold data 1** + +Threshold data are partitioned into two MEs for historical reasons. An instance of this ME, together with an optional instance of the threshold data 2 ME, contains threshold values for counters in PM history data MEs. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be related to multiple instances of PM history data type MEs. + +Paired instances of threshold data 1 ME and threshold data 2 ME are implicitly linked together through a common ME ID. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +The following seven attributes specify threshold values for seven thresholded counters in associated PM history data MEs. The definition of each PM history ME includes a table that links each thresholded counter to one of these threshold value attributes. + +**Threshold value 1:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 2:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 3:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 4:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 5:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 6:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 7:** (R, W, set-by-create) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.12.7 Threshold data 2** + +Together with an instance of the threshold data 1 ME, an instance of this ME contains threshold values for counters maintained in one or more instances of PM history data MEs. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +Refer to the relationships of the threshold data 1 ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value is the same as that of the paired threshold data 1 instance. (R, set-by-create) (mandatory) (2 bytes) + +The following seven attributes specify threshold values for seven thresholded counters in associated PM history data MEs. The definition of each PM history ME includes a table that links each thresholded counter to one of these threshold value attributes. + +**Threshold value 8:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 9:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 10:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 11:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 12:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 13:** (R, W, set-by-create) (mandatory) (4 bytes) + +**Threshold value 14:** (R, W, set-by-create) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.12.8 OMCI** + +This ME describes the ONU's general level of support for OMCI MEs and messages. This ME is not included in an MIB upload. + +#### *Relationships* + +One instance exists in the ONU. The ME entities are related to the OMCI entity. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**ME type table:** This attribute lists the ME classes supported by the ONU. Each entry contains the ME class value (see Table 11.2.4-1) of an ME type. (R) (mandatory) ( $2 * N$ bytes, where $N$ is the number of entries in the list.) + +**Message type table:** This attribute is a list of message types (MTs) supported by the ONU. Each entry contains the MT of an OMCI message (see Table 11.2.2-1). (R) (mandatory) ( $M$ bytes, where $M$ is the number of entries in the list.) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.12.9 Managed entity** + +The ME describes the details of each ME that is supported by the ONU. This ME is not included in an MIB upload. + +#### *Relationships* + +One or more MEs are related to the OMCI object entity. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value is equal to the ME type value, and is the same as the code found in the ME type table attribute of the OMCI ME and Table 11.2.4-1. (R) (mandatory) (2 bytes) + +**Name:** This attribute contains a 25 byte ASCII coded mnemonic tag for the ME type. Strings shorter than 25 bytes are padded with null characters. (R) (mandatory) (25 bytes) + +**Attributes table:** This table contains pointers to the attribute MEs that describe each of this ME's attributes. (R) (mandatory) ( $2 * X$ bytes, where $X$ is the number of entries in the table.) + +NOTE – The ME ID attribute is not included in the list, since the type of this attribute is fixed. + +**Access:** This attribute represents who creates this ME. The following code points are defined. + +- 1 Created by the ONU +- 2 Created by the OLT +- 3 Created by both the ONU and OLT + +(R) (mandatory) (1 byte) + +**Alarms table:** This attribute lists the alarm codes that are supported. (R) (mandatory) ( $Y$ bytes, where $Y$ is the number of entries in the table.) + +**AVCs table:** This attribute lists the AVCs that are supported. (R) (mandatory) ( $Z$ bytes, where $Z$ is the number of entries in the table.) + +**Actions:** This attribute lists the action codes supported on this object, formatted as a bit map. The action codes are the MTs from Table 11.2.2-1. The LSB represents action 0, and so on. (R) (mandatory) (4 bytes) + +**Instances table:** This attribute is a list of pointers to all instances of this ME. (R) (mandatory) ( $2 * V$ bytes, where $V$ is the number of entries in the table.) + +**Support:** This attribute represents the support capability of this ME in the ONU's implementation. This attribute does not declare whether the OMCI implementation complies with the Recommendations, but whether it complies with the OMCI declaration itself. The following code points are defined. + +- 1 Supported (supported as defined in this object) +- 2 Unsupported (OMCI returns error code if accessed) +- 3 Partially supported (some aspects of ME supported) +- 4 Ignored (OMCI supported, but underlying function is not) + +(R) (mandatory) (1 byte) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.12.10 Attribute** + +This ME describes a particular attribute type that is supported by the ONU. This ME is not included in an MIB upload. + +#### *Relationships* + +One or more attribute entities are related to each ME entity. More than one ME entity can refer to a given attribute entity. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This number is the same as the one that appears in the attributes table in the ME. Only one instance of each unique attribute need be created. The ONU can assign attribute numbering as it pleases, out of the pool of 64K IDs; however, it is suggested + +that the numbering follow a rational scheme to aid human readability. (R) (mandatory) (2 bytes) + +**Name:** This attribute contains a 25 byte mnemonic tag for the attribute. Strings shorter than 25 bytes are padded with null characters. (R) (mandatory) (25 bytes) + +**Size:** This attribute contains the size of the attribute, in bytes. The value 0 indicates that the attribute can have a variable/unknown size. (R) (mandatory) (2 bytes) + +**Access:** This attribute represents the OMCI access characteristics of the attribute. The following code points are defined. + +- 1 Read +- 2 Write +- 3 Read, write +- 5 Read, set-by-create +- 6 Write, set-by-create +- 7 Read, write, set-by-create + +(R) (mandatory) (1 byte) + +**Format:** This attribute represents the format of the attribute. The following code points are defined. + +- 1 Pointer +- 2 Bit field +- 3 Signed integer +- 4 Unsigned integer +- 5 String +- 6 Enumeration (that is, a set of defined code points) +- 7 Table + +(R) (mandatory) (1 byte) + +**Lower limit:** This attribute provides the lowest value for the attribute. Valid for numeric types (pointer, signed integer, unsigned integer) only. For attributes smaller than 4 bytes, the desired numeric value is expressed in 4 byte representation (for example, the 2s complement 1 byte integer 0xFE is expressed as 0xFFFF FFFE; the unsigned 1 byte integer 0xFE is expressed as 0x0000 00FE). (R) (mandatory) (4 bytes) + +**Upper limit:** This attribute provides the highest value for the attribute. It has the same validity and format as the lower limit attribute. (R) (mandatory) (4 bytes) + +**Bit field:** This attribute is a mask of the supported bits in a bit field attribute, valid for bit field type only. A 1 in any position signifies that its code point is supported, while 0 indicates that it is not supported. For bit fields smaller than 4 bytes, the attribute is aligned at the least significant end of the mask. (R) (mandatory) (4 bytes) + +**Code points table:** This attribute lists the code points supported by an enumerated attribute. (R) (mandatory) ( $2 * Q$ bytes, where $Q$ is the number of entries in the table.) + +**Support:** This attribute represents the level of support of the attribute (same notation as the attribute of the same name in the ME). The following code points are defined. + +- 1 Fully supported (supported as defined in this object) +- 2 Unsupported (OMCI returns an error code if accessed) +- 3 Partially supported (some aspects of attribute supported) +- 4 Ignored (OMCI supported, but underlying function is not) + +(R) (mandatory) (1 byte) + +#### *Actions* + +Get, get next + +#### *Notifications* + +None. + +### **9.12.11 Octet string** + +The octet string is modelled on the large string ME. The large string is constrained to printable characters because it uses null as a trailing delimiter. The octet string has a length attribute and is therefore suitable for arbitrary sequences of bytes. + +Instances of this ME are created and deleted by the OLT. To use this ME, the OLT instantiates the octet string ME and then points to the created ME from other ME instances. Systems that maintain the octet string should ensure that the octet string ME is not deleted while it is still linked. + +#### *Relationships* + +An instance of this ME may be cited by any ME that requires an octet string that can exceed 25 bytes in length. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The values 0 and 0xFFFF are reserved. (R, set-by-create) (mandatory) (2 bytes) + +**Length:** This attribute specifies the number of octets that comprise the sequence of octets. This attribute defaults to 0 to indicate no octet string is defined. The maximum value of this attribute is 375 (15 parts, 25 bytes each). (R, W) (mandatory) (2 bytes) + +In the following, 15 additional attributes are defined; they are identical. The octet string is simply divided into as many parts as necessary, starting at part 1 and left justified. + +**Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11, Part 12, Part 13, Part 14, Part 15:** +(R, W) (part 1 mandatory, others optional) (25 bytes \* 15 attributes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.12.12 General purpose buffer** + +This ME is created by the OLT when needed to store the results of an operation, such as a test command, that needs to return a block of data of indeterminate size. The buffer is retrieved with get next operations, since its size is not known *a priori*. An instance of this ME is created and deleted by the OLT, and typically made known to an ONU ME or to an action through a pointer. + +The ME is defined as generically as possible, such that it can be used for other applications that may not initially be apparent, such as logging. The format of its content is specific to each application, and is documented there. + +The general purpose buffer is neither captured in an MIB upload, nor retained in a non-volatile ONU memory. + +#### Relationships + +Through a pointer, the OLT may associate a general purpose buffer with an ME or an operation that has a need to create large or indeterminate blocks of data for subsequent upload. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Maximum size:** The ONU determines the actual size of the buffer table in the process of capturing the data directed to it. The maximum size attribute permits the OLT to restrict the maximum size of the buffer table. The value 0 indicates that the OLT imposes no limit on the size; it is recognized that ONU implementations will impose their own limits. The ONU will not create a buffer table larger than the value of this attribute. If the ONU cannot allocate enough memory to accommodate this size, it should deny the ME create action or a write operation that attempts to expand an existing ME. (R, W, set-by-create) (optional) (4 bytes) + +**Buffer table:** This attribute is an octet string that contains the result of some operation performed on the ONU. The exact content depends on the operation, and is documented with the definition of each operation. (R) (mandatory) (*N* bytes) + +#### Actions + +Create, delete, get, get next + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | N/A | | +| 2 | Buffer table | This AVC indicates that the ONU has completed writing the buffer, and thereby signals to the OLT that the operation is complete and the buffer is available for upload. | +| 3..16 | Reserved | | + +### 9.12.13 File transfer controller + +This optional ME allows file transfers to be conducted out of band. It is intended to facilitate software image download, but may be used for other file transfer applications as well. + +#### Relationships + +One instance of this ME exists in an ONU that supports out-of-band file transfer. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is one instance, whose value is 0. (R) (mandatory) (2 bytes) + +**Supported transfer protocols:** This attribute is a bit map. Each bit indicates that the corresponding protocol is (1) or is not (0) supported for file transfers. TFTP is mandatory; the other protocols are optional. (R) (mandatory) (2 bytes) + +| Bit | Protocol | +|---------|----------| +| 1 (LSB) | FTP | + +| | | +|--------|-----------------------------------------------------| +| 2 | TFTP | +| 3 | SFTP | +| 4 | HTTP | +| 5 | HTTPS | +| 6 | FLUTE ([b-IETF RFC 3926]; multicast, download only) | +| 7 | DSM-CC (multicast, download only) | +| 8..12 | Reserved | +| 13..16 | Vendor-specific use; not to be standardized | + +**File type:** This attribute specifies the owner ME type of the file to be transferred. It is a value from Table 11.2.4-1. For example, for software image download, this attribute has the value 7. File systems on circuit packs are identified with the value 6, and on the ONU-G as a whole with the value 256. (R, W) (mandatory) (2 bytes) + +**File instance:** This attribute specifies the instance of the file to be transferred. This attribute is the same as the ME ID attribute of the owner ME. (R, W) (mandatory) (2 bytes) + +**Local file name pointer:** This attribute designates a large string ME that specifies a local file name. Since naming is not specified for any OMCI files, this attribute should be a null pointer in standard OMCI usage, e.g., in the software image case. The use of this attribute for named files is vendor-specific. (R, W) (mandatory) (2 bytes) + +**Network address pointer:** This attribute is a pointer to a network address ME that specifies optional authentication information, along with the URI to be used for the file transfer. The URI should specify the protocol, one from the list of protocols supported by the ONU, an IP address or a string that can be resolved into an IP address, and optionally a port. For unidirectional multicast download (e.g., DSM-CC), the URI should specify a multicast IP source address. (R, W) (mandatory) (2 bytes) + +**File transfer trigger:** This attribute causes the file transfer to begin. If a given set operation writes values to several attributes of this ME, the ONU should apply the file transfer trigger after updating all other attributes. Some operations may not be applicable to some files; the ONU should deny commands that request unsupported actions. (R, W) (mandatory) (1 byte) + +| Value | Meaning | +|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Reserved | +| 1 | Initiate file download (to the ONU) | +| 2 | Initiate file upload (from the ONU) | +| 3 | Abort current file transfer | +| 4 | Delete target file (on the ONU) | +| 5 | Perform a directory listing operation. The scope of the directory is not specified; at the vendor's option, the listing may be filtered by matching some or all of file type, file instance and local file name attributes. | +| 6..255 | Reserved | + +**File transfer status:** This attribute reports the status of a file transfer. (R) (mandatory) (1 byte) + +| Value | Meaning | +|--------|--------------------------------------| +| 0 | File transfer completed successfully | +| 1 | File transfer aborted successfully | +| 2 | File deleted | +| 3 | URL undefined or unreachable | +| 4 | Failure to authenticate | +| 5 | File transfer in progress | +| 6 | Remote failure | +| 7 | Local failure | +| 8..255 | Reserved | + +**GEM IWTP pointer:** This attribute is a pointer that specifies a unicast or multicast GEM IW TP, depending on whether the transfer protocol to be used is unicast or multicast. (R, W) (optional) (2 bytes) + +**VLAN:** This attribute specifies the VLAN to be used for the transfer, assuming multicast protocol. The default value 0 indicates that no VLAN is specified. (R, W) (optional) (2 bytes) + +**File size:** This attribute allows the OLT to specify the size of a file to be downloaded, in bytes. The ONU may use this value to reserve memory or to deny the download command if it has insufficient space. The default value 0 does not specify a file size. (R, W) (optional) (4 bytes) + +**Directory listing table:** When a directory listing is complete, this attribute contains the result of a directory listing operation. The content and format of the table is not specified. (R) (optional) (*N* bytes) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|-------------------------|--------------------------------------------------------------------------------------------------------------------------------| +| 1..6 | N/A | | +| 7 | File transfer status | | +| 8..10 | N/A | | +| 11 | Directory listing table | This AVC signals to the OLT that a directory listing operation is complete and may be retrieved with a get, get next sequence. | +| 12..16 | Reserved | | + +### 9.12.14 Generic status portal + +The generic status portal (GSP) ME provides a way for the OLT to discover the status and configuration information of a non-OMCI management domain within an ONU. The non-OMCI management domain is indicated by the VEIP associated with this GSP. + +The GSP ME uses two table attributes to convey status and configuration from a non-OMCI managed domain to the OMCI. Each of these attributes uses an XML document to present this information. These XML documents are not required to be understood by the OLT or EMS. The schema for the documents may be used in the creation of tools that parse and interpret the contents of the document. + +#### Relationships + +One instance of this ME is created by the OLT for each separate non-OMCI management domain whose information is desired to be visible. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, the GSP ME is implicitly linked to an instance of the VEIP ME. (R, set-by-create) (mandatory) (2 bytes). (R) + +**Status document table:** This attribute is used to pass a textual representation of the non-OMCI managed domain status back to the OLT. The contents are vendor-specific and formatted as an XML document. The first element of the document must contain an XML declaration indicating the version of XML and encoding used in the remainder of the document. The second element of the document must contain a schema reference to the vendor-supplied schema used by the remainder of the document. The get, get next sequence must be used with this attribute since its size is unspecified. (R) (mandatory) (*N* bytes) + +**Configuration document table:** This attribute is used to pass a textual representation of the non-OMCI managed domain configuration back to the OLT. The contents are vendor-specific and formatted as an XML document. The first element of the document must contain an XML declaration indicating the version of XML and encoding used in the remainder of the document. The second element of the document must contain a schema reference to the vendor-supplied schema used by the remainder of the document. The get, get next sequence must be used with this attribute since its size is unspecified. (R) (mandatory) (*M* bytes) + +**AVC report rate:** This attribute governs the rate at which the GSP generates AVC notifications. The default value 0 disables AVCs, while the highest value 3, which may be useful for debugging, generates an AVC on every change seen in the non-OMCI management domain. As a guideline, the value 1 should collect changes into not more than one notification in 10 min, while value 2 should generate an AVC not more than once per second. (R, W, set-by-create) (optional) (1 byte) + +#### Actions + +Create, delete, Get, get next + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Status document table | Indicates an update to the status document table from a non-OMCI interface. Because the attribute is a table, the AVC does not contain information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 2 | Configuration document table | Indicates an update to the configuration document table from a non-OMCI interface. Because the attribute is a table, the AVC does not contain information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 3..16 | Reserved | | + +### 9.12.15 SNMP configuration data + +The SNMP configuration data ME provides a way for the OLT to provision an IP path for an SNMP management agent. + +The SNMP configuration data ME is created and deleted by the OLT. + +#### *Relationships* + +One instance of this ME is created by the OLT for each SNMP management path termination. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. The ME IDs 0 and 0xFFFF are reserved. (R, set-by-create) (mandatory) (2 bytes) + +**SNMP version:** This integer attribute is the SNMP protocol version to be supported. (R, W, set-by-create) (mandatory) (2 bytes) + +**SNMP agent address:** This attribute is a pointer to a TCP/UDP config data ME, which provides the SNMP agent. (R, W, set-by-create) (mandatory) (2 bytes) + +**SNMP server address:** This attribute is the IP address of the SNMP server. (R, W, set-by-create) (mandatory) (4 bytes) + +**SNMP server port:** This attribute is the UDP port number of the SNMP server. (R, W, set-by-create) (mandatory) (2 bytes) + +**Security name pointer:** This attribute points to a large string whose content represents the SNMP security name in a human-readable format that is independent of the security model. SecurityName is defined in [b-IETF RFC 2571]. (R, W, set-by-create) (mandatory) (2 bytes) + +**Community for read:** This attribute is a pointer to a large string that contains the name of the read community. (R, W, set-by-create) (mandatory) (2 bytes) + +**Community for write:** This attribute is a pointer to a large string that contains the name of the write community. (R, W, set-by-create) (mandatory) (2 bytes) + +**Sys name pointer:** This attribute points to a large string whose content identifies the SNMP system name. SysName is defined in [b-IETF RFC 3418]. (R, W, set-by-create) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, Set, get + +#### *Notifications* + +None. + +### 9.12.16 BBF TR-069 management server + +If functions within the ONU are managed by [BBF TR-069], this ME allows OMCI configuration of the autoconfiguration server (ACS) URL and related authentication information for an ACS connection initiated by the ONU. [BBF TR-069] supports other means to discover its ACS, so not all BBF TR-069-compatible ONUs necessarily support this ME. Furthermore, even if the ONU does support this ME, some operators may choose not to use it. + +An ONU that supports OMCI configuration of ACS information automatically creates instances of this ME. + +#### *Relationships* + +An instance of the BBF TR-069 management server ME exists for each instance of a BBF TR-069 management domain within the ONU. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a VEIP that links to the BBF TR-069 management domain. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. When the administrative state is locked, the functions of this ME are disabled. BBF TR-069 connectivity to an ACS may be possible through means that do not depend on this ME. The default value of this attribute is locked. (R,W) (mandatory) (1 byte) + +**ACS network address:** This attribute points to an instance of a network address ME that contains URL and authentication information associated with the ACS URL. (R, W) (mandatory) (2 bytes) + +**Associated tag:** This attribute is a TCI value for BBF TR-069 management traffic passing through the VEIP. A TCI, comprising user priority, CFI and VID, is represented by 2 bytes. The value 0xFFFF specifies that BBF TR-069 management traffic passes through the VEIP with neither a VLAN nor a priority tag. (R, W) (mandatory) (2 bytes) + +#### *Actions* + +Get, set + +### **9.12.17 Threshold data 64 bit** + +An instance of this ME contains threshold values for counters in PM history data MEs. + +Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be related to multiple instances of PM history data type MEs. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +The following attributes specify threshold values for thresholded counters in associated PM history data MEs. The definition of each PM history ME includes a table that links each thresholded counter to one of these threshold value attributes. The default values of these attributes are all 1s. + +**Threshold value 1:** (R, W) (mandatory) (8 bytes) + +**Threshold value 2:** (R, W) (mandatory) (8 bytes) + +**Threshold value 3:** (R, W) (mandatory) (8 bytes) + +**Threshold value 4:** (R, W) (mandatory) (8 bytes) + +**Threshold value 5:** (R, W) (mandatory) (8 bytes) + +**Threshold value 6:** (R, W) (mandatory) (8 bytes) + +**Threshold value 7:** (R, W) (mandatory) (8 bytes) + +**Threshold value 8:** (R, W) (mandatory) (8 bytes) + +**Threshold value 9:** (R, W) (mandatory) (8 bytes) +**Threshold value 10:** (R, W) (mandatory) (8 bytes) +**Threshold value 11:** (R, W) (mandatory) (8 bytes) +**Threshold value 12:** (R, W) (mandatory) (8 bytes) +**Threshold value 13:** (R, W) (mandatory) (8 bytes) +**Threshold value 14:** (R, W) (mandatory) (8 bytes) + +#### **Actions** + +Create, delete, get, set + +#### *Notifications* + +None + +### 9.12.18 OpenFlow config data + +This ME contains the configuration data whose underlying transport method is OpenFlow. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with each instance per OpenFlow transportation channel. There might be more than one OpenFlow transportation channel per ONU. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**TP type:** This attribute specifies the type of ANI-side TP associated with this ME. +1 GEM IW TP +(R, W, set-by-create) (mandatory) (1 byte) + +**TP pointer:** This attribute points to the instance of the TP associated with this OpenFlow configuration data. The type of the associated TP is determined by the TP type attribute. (R, W, set-by-create) (mandatory) (2 bytes) + +**Version:** This integer attribute reports the version of the OpenFlow protocol in use. The ONU should deny an attempt by the OLT to set or create a value that it does not support. The value 0 indicates that no particular version is specified. (R, W, set-by-create) (mandatory) (1 byte) + +**DS OpenFlow message:** This attribute specifies the DS OpenFlow message which is carried over the OMCC channel. (R, W) (mandatory) (24*N* bytes) + +**DS forwarding control:** This Boolean attribute indicates the current DS OpenFlow message is ready to be sent (true) or not. The default value is false. (R, W) (mandatory) (1 byte) + +**DS receiving status:** This Boolean attribute indicates the ONU is ready to accept a new downstream packet (true) or not. The default value is false. (R) (mandatory) (1 byte) + +**US OpenFlow message:** This attribute specifies the US OpenFlow message which is carried over the OMCC channel. (R, W) (mandatory) (24*N* bytes) + +- US receiving control:** This Boolean attribute controls the current US OpenFlow message is safely received (true) or not. The default value is false. (R, W) (mandatory) (1 byte) +- US forwarding status:** This Boolean attribute reports the current US OpenFlow message is ready to be sent (true) or not. The default value is false. (R) (mandatory) (1 byte) +- Circuit ID:** This attribute identifies the first access information of the user +(R, W) (Optional) (24N byte) +- Remote ID:** This attribute identifies the second access information of the user as an addition identifier to circuit ID. (R, W) (Optional) (24N byte) +- Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by the MPLS pseudowire TP. Administrative state is further described in clause A.1.6. (R, W) (optional) (1 byte) +- Operational state:** This attribute reports whether the ME is currently capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +#### Actions + +Create, delete, get, get next, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|---------------------------------------------------------------------------| +| 1..5 | N/A | | +| 6 | DS receiving status | The DS packets receiving status has changed | +| 7..8 | N/A | | +| 9 | US forwarding status | A new ONU response has been loaded into the table for the OLT to retrieve | +| 10-12 | N/A | | +| 13 | Op state | Operational state | +| 14..16 | reserved | | + +### 9.12.19 Time status message + +This ME provides status and characterization information for the time-transmitting node and its grandmaster. An ONU that supports time synchronization automatically creates an instance of this ME. The best practise is to set all the attributes at the same time. + +#### Relationships + +The single instance of this ME is associated with the ONU ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Domain number:** Using the format of clause 7.1 of [IEEE 1588]. The default value is 0. (R, W) (mandatory) (1 byte) + +| Flag Field:
The field format is given in the table. Value 1 represents "true". (R, W) (mandatory) (1 byte)Bits | Usage | +|-------------------------------------------------------------------------------------------------------------------|-----------------------| +| 1 (LSB) | Leap61 | +| 2 | Leap59 | +| 3 | currentUtcOffsetValid | +| 4 | PTP timescale | +| 5 | Time traceable | +| 6 | Frequency traceable | +| 7 | Reserved | +| 8 (MSB) | Reserved | + +**currentUtcOffset:** Provides the UTC offset value between the TAI and UTC timescales (UTC Offset = TAI – UTC), as specified in clause 7.2.3 of [IEEE 1588]. (R, W) (mandatory) (2 bytes) + +**Priority1:** As specified in clause 7.6.2.2 of [IEEE 1588]. (R, W) (mandatory) (1 byte) + +**clockClass:** Provides the clockClass information denoting the traceability of the time distributed by the grandmaster clock, as specified in clause 7.6.2.4 of [IEEE 1588]. (R, W) (mandatory) (1 byte) + +**Accuracy:** Indicates the expected accuracy of a clock when it is the grandmaster, as specified in clause 7.6.2.5 of [IEEE 1588]. (R, W) (mandatory) (1 byte) + +**offsetScaledLogVariance:** Provides the estimate of the time variance, as specified in clause 7.6.3 of [IEEE 1588]. (R, W) (mandatory) (2 bytes) + +**Priority2:** As specified in clause 7.6.2.3 of [IEEE 1588]. (R, W) (mandatory) (1 byte) + +**Grandmaster ID:** The clockIdentity attribute of the grandmaster, taken from the IEEE EUI-64 individual assigned numbers. (R, W) (mandatory) (8 bytes) + +**Steps removed:** Provides the number of boundary clocks between the local clock and the master. (R, W) (mandatory) (2 bytes) + +**Time source:** Indicates the source of time used by the grandmaster clock, as specified in clause 7.6.2.6 of [IEEE 1588]. (R, W) (mandatory) (1 byte) + +#### Actions + +Get, set + +#### Notifications + +None. + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Clock unlock | ITU-T G.781 clock unlock defect: If the status of the system clock is unlocked, a clock unlock is declared. The defect is cleared if the status of the system clock is "locked". Note that "unlocked" is a status of the clock, not a clock mode. | +| 1 | ESMC loss | ITU-T G.781 loss of ESMC channel. If no valid ESM PDU is received for 5 seconds, a loss of ESMC (LOESMC) is detected. The LOESMC defect is cleared upon the first ESMC PDU. | +| 2 | Time unlock | ITU-T G.781.1 time unlock (1PPS+TOD input). Alarm is declared when the system time is unlocked to the time source. | +| 3..207 | Reserved | Reserved for vendor-specific alarms. | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.12.20 BBF TR-369 USP agent + +The BBF TR-369 USP agent ME models a USP Agent and the configuration needed to establish communications between the USP Agent and a USP Controller. + +[BBF TR-369] supports other means to discover its controller (e.g., pre-configured in firmware, DHCP/DNS/mDNS discovery, and through another known trusted controller). This ME is therefore optional (an ONU vendor may choose to implement it, and an operator may choose not to configure the USP controller through this ME if supported by the ONU vendor). + +An ONU that supports OMCI configuration of USP information automatically creates instances of this ME + +#### *Relationships* + +An instance of the BBF TR-369 USP agent ME points to the virtual Ethernet interface point (VEIP) ME. This ME is used for associating USP as a non-OMCI management domain. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a VEIP. (R) (mandatory) (2 bytes) + +**Available USP Message Transfer Protocols:** This table is a list of IANA registered service-name for the available MTPs: + +**Service name:** The service name of the USP MTP. It is a character string, padded with trailing nulls if it is shorter than 15 bytes (15 bytes) + +(R) (mandatory) (15*N* bytes) + +**Controller table:** Each record in the table (indexed by the controller network address) is comprised of the following fields: + +**Controller network address:** This attribute points to an instance of a network address ME that contains an FQDN or absolute URL identifying the controller (e.g., "://example.com:/"). (2 bytes) + +**Table control:** This field controls the meaning of a set operation. The 1 byte size of this field is included in get/get-next operations, but its value is undefined under get-next and should be ignored by the OLT. (1 byte) + +- 1 Add record to table; overwrite existing record, if any. +- 2 Delete record from table. +- 3 Clear all entries from table. This action may affect service and should be used judiciously. + +Other values are reserved. + +**Associated tag:** This field is a TCI value for BBF TR-369 management traffic passing through the VEIP. A TCI, comprising user priority, CFI and VID, is represented by 2 bytes. The value 0xFFFF specifies that BBF TR-369 management traffic passes through the VEIP with neither a VLAN nor a priority tag. (2 bytes) + +**Provisioning Code:** This attribute points to a large string ME that contains the provisioning code (64 character UTF-8 string) that identifies the primary service provider and other provisioning information, which may be used by the Controller to determine service provider specific customization and provisioning parameters. A 0xFFFF null pointer indicates the absence of a provisioning code. (2 bytes) + +**USP retry minimum wait interval:** This attribute configures the first retry wait interval in seconds as specified in TR-369 "Failure Handling in the session Context". The default value of 5 seconds is used. (2 bytes) + +**USP retry interval multiplier:** This attribute configures the retry interval multiplier as specified in TR-369 "Failure Handling in the session Context". This value must be expressed in units of 0.001. Values range between 1000 and 65535. The default value of 2000 is used. (2 bytes) + +**Message Transfer Protocol (MTP) Used:** The service name of the USP MTP. It is a character string, padded with trailing nulls if it is shorter than 15 bytes (15 bytes) + +(R,W) (mandatory) (26N bytes) + +#### *Actions* + +Get, get next, set + +Set table (optional) + +#### *Notifications* + +None. + +### **9.12.21 Synchronous Ethernet operation** + +This ME configures the ONU's ability to monitor and control the Synchronous Ethernet (SyncE) operation capability as defined in [ITU G.8264]. + +An ONU that supports SyncE automatically creates or deletes an instance of this ME. + +#### *Relationships* + +A single instance of this ME is associated with the ONU-G ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Options:** This attribute configures the expected network QL states (please refer to clause 11.3.2.1 of [ITU G.8264] on QL generation. The following QL types are supported: + +- 0 ITU-T G.8264 EEC option 1 network +- 1 ITU-T G.8264 EEC option 2 network +- 2 ITU-T G.8262.1 eEEC option 1 network +- 3 ITU-T G.8262.1 eEEC option 2 network + +The default value is 0. (R, W) (mandatory) (1 byte) + +**ESMC QL state:** This attribute is an enumeration that returns the received ONU SSM and enhanced SSM code. See clause 11.3.2.2 QL Reception, Table 11-7 and Table 11-8 in [ITU G.8264]. Its values are defined as follows. + +| Options | ITU-T G.8264 QL State | Byte 1 (LSB) | Byte 2 | +|---------------|----------------------------|--------------|-------------------| +| | | SSM Code | Enhanced SSM Code | +| EEC Option 1 | QL-PRC | 0010 | 0xFF | +| | QL-SSU-A | 0100 | 0xFF | +| | QL-SSU-B | 1000 | 0xFF | +| | QL-EEC1 | 1011 | 0xFF | +| | QL-DNU | 1111 | 0xFF | +| | Other values are reserved. | | | +| EEC Option 2 | QL-STU | 0000 | 0xFF | +| | QL-PRS | 0001 | 0xFF | +| | QL-TNC | 0100 | 0xFF | +| | QL-ST2 | 0111 | 0xFF | +| | QL-EEC2 | 1010 | 0xFF | +| | QL-ST3 | 1010 | 0xFF | +| | QL-ST3E | 1101 | 0xFF | +| | QL-PROV | 1110 | 0xFF | +| | QL-DUS | 1111 | 0xFF | +| | Other values are reserved. | | | +| eEEC Option 1 | QL-PRC | 0010 | 0xFF | +| | QL-SSU-A | 0100 | 0xFF | +| | QL-SSU-B | 1000 | 0xFF | +| | QL-EEC1 | 1011 | 0xFF | +| | QL-DNU | 1111 | 0xFF | +| | QL-PRTC | 0010 | 0x20 | +| | QL-ePRTC | 0010 | 0x21 | +| | QL-eEEC | 1011 | 0x22 | +| | QL-ePRC | 0010 | 0x23 | +| | | | | +| eEEC Option 2 | QL-STU | 0000 | 0xFF | + +| Options | ITU-T G.8264 QL State | Byte 1 (LSB)
SSM Code | Byte 2
Enhanced SSM
Code | +|---------|-----------------------|--------------------------|--------------------------------| +| | QL-PRS | 0001 | 0xFF | +| | QL-TNC | 0100 | 0xFF | +| | QL-ST2 | 0111 | 0xFF | +| | QL-EEC2 | 1010 | 0xFF | +| | QL-ST3 | 1010 | 0xFF | +| | QL-ST3E | 1101 | 0xFF | +| | QL-PROV | 1110 | 0xFF | +| | QL-DUS | 1111 | 0xFF | +| | QL-PRTC | 0001 | 0x20 | +| | QL-ePRTC | 0001 | 0x21 | +| | QL-eEEC | 1010 | 0x22 | +| | QL-ePRC | 0001 | 0x23 | + +(R) (mandatory) (2 byte) + +**ESMC QL generation:** This attribute is an enumeration that returns the current generated ONU ESM quality level. The ESMC QL values an associated SSM codes are same as specified for the ESMC QL state attribute. See clause 11.3.2.1 QL Generation in [ITU G.8264]. + +(R) (mandatory) (2 bytes) + +**Tx ESMC Informational PDUs:** This attribute increments when an ESMC Informational PDU is sent by the ONU. When full, the counter rolls over to 0. (R) (mandatory) (4 bytes) + +**Rx ESMC Informational PDUs:** This attribute increments when an ESMC Informational PDU is received by the ONU. When full, the counter rolls over to 0. (R) (mandatory) (4 bytes) + +**Tx ESMC Event PDUs:** This attribute increments when an ESMC event PDU is sent by the ONU. When full, the counter rolls over to 0. (R) (mandatory) (4 bytes) + +**Rx ESMC Event PDUs:** This attribute increments when an ESMC event PDU is received by the ONU When full, the counter rolls over to 0. (R) (mandatory) (4 bytes) + +**QL-DNU Event counter:** This attribute increments when the QL state transitions to DNU from a non-DNU state per section 11.3.2.2 QL Reception [ITU G.8264]. When full, the counter rolls over to 0. (R) (optional) (4 bytes) + +#### Actions + +Get, set + +#### Notifications + +None + +### 9.12.22 Precision Time Protocol + +This ME configures the ONU's ability to control the Precision Time Protocol (PTP) capability of the ONU as defined in IEEE 1588v2. + +An ONU that supports PTP automatically creates an instance of this ME. + +#### *Relationships* + +The single instance of this ME is associated with the ONU ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) The default value is 1. (1 byte) + +**Communication model:** This attribute specifies the communication model of PTP packets encapsulation. See clause 6.2 in [IEEE 1588v2]. Its values are defined as follows: + +- 0 multicast +- 1 unicast + +The default value is 0. (R, W) (mandatory) (1 byte) + +**Network transport protocol:** This attribute specifies the network protocol of PTP packets encapsulation. See clause 7.4.1 Network transport protocol in [IEEE 1588v2]. Its values are defined as follows: + +- 0x0000 Reserved +- 0x0001 UDP/IPv4 +- 0x0002 UDP/IPv6 +- 0x0003 IEEE 802.3 + +All other values are reserved. + +The default value is 0x0003. (R, W) (mandatory) (2 bytes) + +**Multicast address mode:** This attribute specifies the transmitted multicast destination MAC address when transmitting PTP messages to a remote PTP port (when IEEE 802.3 Network Transport protocol is selected). Two multicast addresses are supported to handle operator preferences of whether to forward PTP messages in a PTP unaware network. See [IEEE 1588v2] clause F.3 and [ITU-T G.8275.1] Appendix III for more details. The following values are supported: + +- 0 Non-forwardable multicast address (multicast address 01-80-C2-00-00-0E) will be used on transmitted PTP message +- 1 Forwardable multicast address (multicast address 01-1B-19-00-00-00) will be used on transmitted PTP message + +All other values are reserved. + +The default value is 0. (R, W) (mandatory) (1 byte) + +**PTP source address:** This attribute specifies the source address for PTP packets. If the value is 0.0.x.y, where x and y are not both 0, then x.y is to be interpreted as a pointer to a large string ME that represents an IPv6 address. Otherwise, the address is an IPv4 address. + +The default value is 0. (R, W) (mandatory) (4 bytes) + +**Downstream Packet TCI:** This attribute specifies the VLAN of PTP packets encapsulation. Default value is 0. (R, W) (mandatory) (3 bytes) + +The first byte defines the control type: + +- 0 PTP packets are untagged. The remaining 2 bytes of the attribute are ignored. +- 1 PTP packets are tagged with the TCI specified in bytes 2 and 3 of this attribute. + +The second and third bytes specifies the TCI (VLAN ID and P-bits) to be applied to the PTP packet if the control byte indicates a tagged format. + +**Clock step:** This attribute specifies the ONU clock is one-step clock or two-step clock. Default value is 0. + +- 0 one-step +- 1 two-step + +(R, W) (mandatory) (1 byte) + +**Log announce interval:** This attribute specifies the base-2 logarithm of the mean time interval in seconds between successive ONU Announce messages (see clause 7.7.2.2 in [IEEE 1588v2]). The format is a signed integer. Default value is 0 (implement specific). (Refer to clause 8.2.5.4.1 of [IEEE 1588v2]). + +(R, W) (mandatory) (1 byte) + +**Log sync interval:** This attribute specifies base-2 logarithm of the mean SyncInterval in seconds for multicast messages. The rates for unicast transmissions are negotiated separately on a per-port basis and are not constrained by this attribute(see clause 7.7.2.3 in [IEEE 1588v2]). The format is a signed integer. Default value is 0. (Refer to clause 8.2.5.4.3 of [IEEE 1588v2]). + +(R, W) (mandatory) (1 byte) + +**ToD update interval:** This attribute specifies the expected time of day (ToD) update interval in minutes. This interval is used for determining whether the ONU clock state enters holdover mode (see clause 9.12.23). The format is a non-signed integer. Valid values are 0 to 1440 minutes, as recommended in clause 10.4.6.2 of [ITU-T G.984.3] for ToD refresh interval. Default value is 0. + +(R, W) (mandatory) (2 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +None + +### **9.12.23 Precision Time Protocol status** + +This ME supplements the Precision Time Protocol ME. Its purpose is to return information that may help in system- or network-level troubleshooting. An ONU that supports PTP automatically creates or deletes an instance of this ME. + +#### *Relationships* + +The single instance of this ME is associated with the PTP ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**Clock identity:** This attribute identifies the clock identity attribute of the ONU PTP clock as specified in clause 7.5.2.2 of [IEEE 1588v2]. It is expressed as a binary value of 8 octets. + +(R) (mandatory) (8 bytes) + +**Clock state:** This attribute indicates the current ONU PTP clock state. The following clock states (based on [ITU-T G.8275 Appendix VIII.2] clock modes) are supported: + +0x00 Free-Run mode: The operating condition of the ONU clock has lost traceability to the OLT-G ME ToD timestamp. This may occur when PTP is disabled, or PTP is enabled and OLT-G ME ToD information is invalid. + +0x01 Holdover-in-specification mode: The operating condition of the ONU clock has lost traceability to the controlling OLT-G ME ToD BUT is using the last valid OLT-G ME ToD timestamp and its performance is within desired specification. The ONU clock stopped receiving OLT-G ME ToD timestamps for more than the 3 times the ToD update interval. + +0x02 Holdover-out-of-specification mode: The operating condition of the ONU clock has lost traceability to the controlling OLT-G ME ToD BUT is using the last valid OLT-G ME ToD timestamp and its performance is outside desired specification. + +0x03 Locked mode: The operating condition of the ONU clock is locked/controlled by received OLT-G ToD. The ONU clock is receiving OLT-G ME ToD timestamps within 3 times the ToD update interval) + +Note: The [ITU-T G.8275] clock mode of "Acquiring" is indicated as "Free-run". + +(R) (mandatory) (1 byte) + +**Clock state change time:** A UTC timestamp at which the ONU last changed the clock state. + +(R) (mandatory) (4 bytes) + +**Tx sync messages:** This attribute increments when a sync message is sent by the ONU. When full, the counter rolls over to 0. + +(R) (mandatory) (4 bytes) + +**Tx follow up messages:** This attribute increments when a follow up message is sent by the ONU. When full, the counter rolls over to 0. + +(R) (mandatory) (4 bytes) + +**Tx announce messages:** This attribute increments when an announce message is sent by the ONU. When full, the counter rolls over to 0. + +(R) (mandatory) (4 bytes) + +**Rx delay request messages:** This attribute increments when a delay request message is received by the ONU. When full, the counter rolls over to 0. + +(R) (mandatory) (4 bytes) + +**Tx delay response messages:** This attribute increments when a delay response message is sent by the ONU. When full, the counter rolls over to 0. + +(R) (mandatory) (4 bytes) + +**PTP slave table:** This attribute is a list of synchronized ptp slave nodes detected by ONU. Note: Only discovered ptp slave node whose PTP timeout timer has not expired are included in this table (see clause 7.7.3 (PTP timeout timer) of [IEEE 1588v2]). Each table entry has the below form: + +**MAC address:** A unique identifier of the slave node within the table (6 bytes) + +**Source IP address:** This component specifies the slave source IP address. May be either an IPv4 address (first 12 bytes 0) or an IPv6 address. (16 bytes) + +**Timestamp:** A UTC timestamp at which the ONU detected the slave node. (4 bytes) + +(R) (mandatory) (26N bytes) + +#### *Actions* + +Get, Get next + +#### *Notifications* + +None + +## **9.13 Miscellaneous services** + +### **9.13.1 Physical path termination point video UNI** + +This ME represents an RF video UNI in the ONU, where physical paths terminate and physical path level functions are performed. + +The ONU automatically creates an instance of this ME per port: + +- when the ONU has RF video UNI ports built into its factory configuration; +- when a cardholder is provisioned to expect a circuit pack of the video UNI type; +- when a cardholder provisioned for plug-and-play is equipped with a circuit pack of the video UNI type. Note that the installation of a plug-and-play card may indicate the presence of video ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies video ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a video circuit pack, nor is it equipped with a video circuit pack. + +#### *Relationships* + +One or more instances of this ME are associated with an instance of a real or virtual circuit pack classified as video type. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Power control:** This attribute controls whether power is provided from the ONU to an external equipment over the video PTPP. Value 1 enables power over coaxial cable. The default value 0 disables power feed. (R, W) (optional) (1 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of video UNI | +| 3 | ARC | ARC timer expiration | +| 4..5 | N/A | | +| 6..16 | Reserved | | + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|------------------------|-------------------------------------| +| 0 | Video-LOS | No signal at the video UNI | +| 1 | Video-OOR-low | RF output below rated value | +| 2 | Video-OOR-high | RF output above rated value | +| 3..207 | Reserved | Reserved for vendor-specific alarms | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### **9.13.2 Physical path termination point video ANI** + +This ME represents an RF video ANI in the ONU, where physical paths terminate and physical path level functions are performed. + +The ONU automatically creates an instance of this ME per port as follows. + +- When the ONU has video ANI ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the video ANI type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the video ANI type. Note that the installation of a plug-and-play card may indicate the presence of video ANI ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies video ANI ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a video ANI circuit pack, nor is it equipped with a video ANI circuit pack. + +#### *Relationships* + +An instance of this ME is associated with each instance of a real or pre-provisioned video ANI port. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the ANI. The first byte is the slot ID + +(defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. +(R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Frequency range low:** This attribute indicates the lower of the two possible frequency ranges supported. Different frequency ranges are indicated by code points: + +| | | +|--------|-------------| +| 0 | No low band | +| 1 | 50..550 MHz | +| 2 | 50..750 MHz | +| 3 | 50..870 MHz | +| 4..255 | Reserved | + +(R) (mandatory) (1 byte) + +**Frequency range high:** This attribute indicates the higher of the two frequency ranges supported. Different frequency ranges are indicated by code points: + +| | | +|--------|----------------| +| 0 | No high band | +| 1 | 550..750 MHz | +| 2 | 550..870 MHz | +| 3 | 950..2050 MHz | +| 4 | 2150..3250 MHz | +| 5 | 950..3250 MHz | +| 6..255 | Reserved | + +(R) (mandatory) (1 byte) + +**Signal capability:** This attribute indicates the capability of the ONU to measure the video signal level. Capabilities are indicated by code points, as follows. + +| | | +|--------|-------------------------------------------------------------------------| +| 0 | No signal level measurement capability | +| 1 | Total optical power level | +| 2 | Fixed frequency pilot tone power level | +| 3 | Total optical power level and fixed frequency pilot tone power level | +| 4 | Variable frequency pilot tone power level | +| 5 | Total optical power level and variable frequency pilot tone power level | +| 6 | Broadband RF power level | +| 7 | Total optical power level and broadband RF power level | +| 8..255 | Reserved | + +(R) (mandatory) (1 byte) + +**Optical signal level:** This attribute is an unsigned integer that returns the current measurement of the total optical signal level. The unit of this attribute is decibel-microwatt optical. + +- If signal capability = 0, 2, 4 or 6, this attribute is undefined. +- If signal capability = 1, 3, 5 or 7, this attribute describes the total optical power that is generating photocurrent on the receiver. + +(R) (optional) (1 byte) + +**Pilot signal level:** This attribute indicates the current measurement of the pilot signal level or broadband RF level. The unit of this attribute is decibel-microvolt at the RF video service port. + +- If signal capability = 0 or 1, then this attribute is undefined. +- If signal capability = 2, 3, 4 or 5, this attribute reports the pilot signal level at the output of the video UNI. +- If signal capability = 6 or 7, this attribute reports the total RF power level at the output of the video UNI. + +(R) (optional) (1 byte) + +**Signal level min:** This attribute indicates the minimum optical RF power per channel that results in a CNR of 47 dBc for a channel of 4.5 MHz bandwidth at a receive optical power of -5 dBm. The unit of this attribute is decibel-microwatt optical. (R) (mandatory) (1 byte) + +**Signal level max:** This attribute indicates the maximum optical RF power per channel that results in a CTB of -57 dBc for an 80-channel ensemble of carriers at a per-channel optical modulation index (OMI) of 3.5%. The unit of this attribute is decibel-microwatt optical. (R) (mandatory) (1 byte) + +**Pilot frequency:** This attribute specifies the frequency of the pilot channel receiver. The unit of this attribute is hertz. + +- If signal capability = 0, 1, 6 or 7, this attribute is undefined. +- If signal capability = 2 or 3, this attribute is functionally RO. +- If signal capability = 4 or 5, this attribute is RW. + +(R, W) (optional) (4 bytes) + +**AGC mode:** This attribute allows the discovery and configuration of the ONU's AGC capabilities. The attribute contains a code point for several AGC types. The ONU displays the currently used AGC mode. The OLT can discover new modes via the set command; the ONU denies attempts to set an unsupported mode. The code points are as follows. + +- | | | +|--------|------------------| +| 0 | No AGC | +| 1 | Broadband RF AGC | +| 2 | Optical AGC | +| 3..255 | Reserved | + +(R, W) (optional) (1 byte) + +**AGC setting:** This attribute indicates the measurement offset that the ONU should use in AGC. The attribute has a step size of 0.1 dB, represented as a signed integer. + +The theoretical nominal RF signal is 80 channels of NTSC video, each with a per-channel OMI of 3.5%. An ONU presented with such a signal should produce its specified output when this attribute is set to zero. + +If total optical power is used for AGC, this attribute provides the OMI offset for any NTSC carriers present from the theoretical 3.5% value. For example, + +if the actual signal uses an OMI of 7.0% per channel (3 dB higher), then the ONU should be given an AGC setting of 30 (coded 0x1E). + +If broadband RF power is used for AGC, this attribute provides the total power offset for any NTSC carriers present from the theoretical 80-channel value. For example, if an actual signal contains 40 NTSC channels (3 dB lower), then the ONU should be given an AGC setting of -30 (coded 0xE2). + +(R, W) (optional) (1 byte) + +**Video lower optical threshold:** This attribute specifies the optical level used to declare the video OOR low alarm. Valid values are -12 to +6 dBm in 0.1 dB increments, represented as a 2s complement integer. (Coding -120 to +60, where 0x00 = 0 dBm, 0x88 = -12.0 dBm, etc.) Upon ME instantiation, the ONU sets this attribute to 0xA1 (-9.5 dBm). (R, W) (optional) (1 byte) + +NOTE – Because the power measurement returned in the optical signal level attribute has a resolution of 1 dB, it is possible that the measured value could appear to be in-range, even though an out-of-range alarm has been declared against a threshold with 0.1 dB resolution. + +**Video upper optical threshold:** This attribute specifies the optical level used to declare the video OOR high alarm. Valid values are -12 to +6 dBm in 0.1 dB increments, represented as a 2s complement integer. (Coding -120 to +60, 0x00 = 0 dBm, 0x88 = -12.0 dBm, etc.) Upon ME instantiation, the ONU sets this attribute to 0x19 (+2.5 dBm). (R, W) (optional) (1 byte) + +#### Actions + +Get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of video ANI | +| 3 | ARC | ARC timer expiration | +| 4..16 | N/A | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|------------------------|----------------------------------------------------------| +| 0 | Video LOS | No signal at the video ANI | +| 1 | Video OOR low | Signal strength below lower optical threshold (optional) | +| 2 | Video OOR high | Signal strength above upper optical threshold (optional) | +| 3..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.13.3 Physical path termination point LCT UNI + +This ME models debug access to the ONU from any physical or logical port, for example, via a dedicated LCT UNI, via ordinary subscriber UNIs, or via the IP host config ME. + +The ONU automatically creates an instance of this ME per port: + +- when the ONU has an LCT port built into its factory configuration; +- when a cardholder is provisioned to expect a circuit pack of the LCT type; +- when a cardholder provisioned for plug-and-play is equipped with a circuit pack of the LCT type; + +NOTE – The installation of a plug-and-play card may indicate the presence of LCT ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies LCT ports. + +- when the ONU supports debug access through some other physical or logical means. + +The ONU automatically deletes an instance of this ME when a cardholder is neither provisioned to expect an LCT circuit pack, nor is it equipped with an LCT circuit pack, or if the ONU is reconfigured in such a way that it no longer supports debug access. + +LCT instances are not reported during an MIB upload. + +#### *Relationships* + +An instance of this ME is associated with an instance of a real or virtual circuit pack ME classified as an LCT type. An instance of this ME may also be associated with the ONU as a whole, if the ONU supports debug access through means other than a dedicated physical LCT port. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. If the LCT UNI is associated with the ONU as a whole, its ME ID should be 0. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is described generically in clause A.1.6. The LCT has additional administrative state behaviour. When the administrative state is set to lock, debug access through all physical or logical means is blocked, except that the operation of a possible ONU remote debug ME is not affected. Administrative lock of ME instance 0 overrides administrative lock of any other PPTP LCT UNIs that may exist. (R, W) (mandatory) (1 byte) + +#### *Actions* + +Get, set + +#### *Notifications* + +None. + +### **9.13.4 Interworking VCC termination point** + +An instance of this ME represents a point in the ONU where the IW of a service or underlying physical infrastructure (e.g., ADSL) to an ATM layer takes place. At this point, ATM cells are generated from a bit stream (e.g., Ethernet) or a bit stream is reconstructed from ATM cells. + +Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +One instance of this ME exists for each occurrence of transformation of a data stream into ATM cells and *vice versa*. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**VCI value:** This attribute identifies the VCI value associated with this IW VCC TP. (R, W, set-by-create) (mandatory) (2 bytes) + +**VP network CTP connectivity pointer:** This attribute points to the VP network CTP associated with this IW VCC TP. (R, W, set-by-create) (mandatory) (2 bytes) + +**Deprecated 1:** Not used; should be set to 0. (R, W, set-by-create) (mandatory) (1 byte) + +**Deprecated 2:** Not used; should be set to 0. (R, W, set-by-create) (mandatory) (2 bytes) + +**AAL5 profile pointer:** This attribute points to an instance of the AAL5 profile. (R, W, set-by-create) (mandatory) (2 bytes) + +**Deprecated 3:** Not used; should be set to 0. (R, W, set-by-create) (mandatory) (2 bytes) + +**AAL loopback configuration:** This attribute sets the ATM loopback configuration. All code points are retained for backward compatibility, but some are not expected to be needed in current and future applications. + +- 0 No loopback +- 1 Loopback 1, loopback of downstream traffic before FEC of AAL1 +- 2 Loopback 2, loopback of downstream traffic after FEC of AAL1 +- 3 Loopback after AAL, loopback of downstream traffic after any AAL. Loopback after AAL is depicted in Figure 9.13.4-1. + +![Diagram of AAL loopback configuration in an ONU. The ONU contains an 'ATM interworking' block and an 'Ethernet over GEM' block. An 'xDSL UNI' is connected to the 'ATM interworking' block. A 'PON' is connected to the 'Ethernet over GEM' block. A loopback arrow labeled 'Loopback after AAL' is shown within the 'ATM interworking' block, indicating a feedback path for downstream traffic.](8573ed5013dc9c3c21a9e6a66a7019a9_img.jpg) + +Diagram of AAL loopback configuration in an ONU. The ONU contains an 'ATM interworking' block and an 'Ethernet over GEM' block. An 'xDSL UNI' is connected to the 'ATM interworking' block. A 'PON' is connected to the 'Ethernet over GEM' block. A loopback arrow labeled 'Loopback after AAL' is shown within the 'ATM interworking' block, indicating a feedback path for downstream traffic. + +G.988(12)\_F9.13.4-1 + +**Figure 9.13.4-1 – AAL loopback configuration** + +The default value of this attribute is 0. (R, W) (mandatory) (1 byte) + +**PPTP counter:** This value is the number of instances of PPTP MEs associated with this instance of the IW VCC TP. (R) (optional) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +#### Actions + +Create, delete, get, set + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------| +| 1..8 | N/A | | +| 9 | Op state | Operational state change | +| 10..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------| +| 0 | End-to-end VC AIS layer management indication receiving (LMIR) | End-to-end VC-AIS receiving indication (optional) | +| 1 | End-to-end VC RDI LMIR | End-to-end VC-RDI receiving indication (optional) | +| 2 | End-to-end VC AIS layer management indication generation (LMIG) | End-to-end VC-AIS generation indication (optional) | +| 3 | End-to-end VC RDI LMIG | End-to-end VC-RDI generation indication (optional) | +| 4 | Segment loss of continuity | Loss of continuity detected when the interworking VCC termination point is a segment end point (optional) | +| 5 | End-to-end loss of continuity | Loss of continuity detected at the interworking VCC termination point (optional) | +| 6 | CSA | Cell starvation alarm | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.13.5 AAL5 profile + +This ME organizes data that describe the AAL type 5 processing functions of the ONU. It is used with the IW VCC TP ME. + +This ME is created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME may be associated with zero or more instances of the IW VCC TP. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Max CPCS PDU size:** This attribute specifies the maximum CPCS PDU size to be transmitted over the connection in both upstream and downstream directions. (R, W, set-by-create) (mandatory) (2 bytes) + +**AAL mode:** This attribute specifies the AAL mode as follows. + +- 0 Message assured +- 1 Message unassured +- 2 Streaming assured +- 3 Streaming non assured + +(R, W, set-by-create) (mandatory) (1 byte) + +**SSCS type:** This attribute specifies the SSCS type for the AAL. Valid values are as follows. + +- 0 Null +- 1 Data SSCS based on SSCOP, assured operation +- 2 Data SSCS based on SSCOP, non-assured operation +- 3 Frame relay SSCS + +(R, W, set-by-create) (mandatory) (1 byte) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +None. + +### **9.13.6 AAL5 performance monitoring history data** + +This ME collects PM data as a result of performing segmentation and reassembly (SAR) and convergence sublayer (CS) level protocol monitoring. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of an IW VCC TP that represents AAL5 functions. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the IW VCC TP. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Sum of invalid CS field errors:** This attribute counts the sum of invalid CS field errors. For AAL type 5, this attribute is a single count of the number of CS PDUs discarded due to one of the following error conditions: invalid common part indicator (CPI), oversized received SDU, or length violation. (R) (mandatory) (4 bytes) + +**CRC violations:** This attribute counts CRC violations detected on incoming SAR PDUs. (R) (mandatory) (4 bytes) + +**Reassembly timer expirations:** This attribute counts reassembly timer expirations. (R) (mandatory if reassembly timer is implemented) (4 bytes) + +**Buffer overflows:** This attribute counts the number of times where there was not enough buffer space for a reassembled packet. (R) (mandatory) (4 bytes) + +**Encap protocol errors:** This attribute counts the number of times that [IETF RFC 2684] encapsulation protocol detected a bad header. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|------------------------------|--------------------------------------| +| 0 | Invalid fields | 1 | +| 1 | CRC violation | 2 | +| 2 | Reassembly timer expirations | 3 | +| 3 | Buffer overflows | 4 | +| 4 | Encap protocol errors | 5 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### 9.13.7 This clause is intentionally left blank + +### 9.13.8 This clause is intentionally left blank + +### 9.13.9 VP network CTP + +NOTE – In [ITU-T G.984.4], this ME is called VP network CTP-G. + +This ME represents the termination of VP links on an ONU. It aggregates connectivity functionality from the network view and alarms from the network element view as well as artefacts from trails. Instances of this ME are created and deleted by the OLT. + +An instance of the VP network CTP ME can be deleted only when no ATM IW VCC TP is associated with it. It is the responsibility of the OLT to ensure that this condition is met. + +#### Relationships + +Zero or more instances of the VP network CTP ME may exist for each instance of the IW VCC TP ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**VPI value:** This attribute identifies the VPI value associated with the VP link being terminated. (R, W, set-by-create) (mandatory) (2 bytes) + +**UNI pointer:** This pointer indicates the xDSL PPTP UNI associated with this VP TP. The bearer channel may be indicated by the two MSBs of the pointer. (R, W, set-by-create) (mandatory) (2 bytes) + +**Direction:** This attribute specifies whether the VP link is used for UNI-to-ANI (value 1), ANI-to-UNI (value 2), or bidirectional (value 3) connection. (R, W, set-by-create) (mandatory) (1 byte) + +**Deprecated 1:** Not used; should be set to 0. (R, W, set-by-create) (mandatory) (2 bytes) + +**Deprecated 2:** Not used; should be set to 0. (R, W, set-by-create) (mandatory) (2 bytes) + +**Deprecated 3:** Not used; should be set to 0. (R, W, set-by-create) (optional) (2 bytes) + +**Deprecated 4:** Not used; if present, should be set to 0. (R) (optional) (1 byte) + +#### Actions + +Create, delete, get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-------------------------------|-----------------------------------------------------------------------------------------------------------| +| 0 | VP AIS LMIR | VP-AIS receiving indication | +| 1 | VP RDI LMIR | VP-RDI receiving indication | +| 2 | VP AIS LMIG | VP-AIS generation indication | +| 3 | VP RDI LMIG | VP-RDI generation indication | +| 4 | Segment loss of continuity | Loss of continuity is detected when the VP network CTP is a segment end point | +| 5 | End-to-end loss of continuity | Loss of continuity can be detected when the VP network CTP supports an interworking VCC termination point | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.13.10 VP performance monitoring history data + +This ME collects PM data associated with a VP network CTP. Instances of this ME are created and deleted by the OLT. + +#### Relationships + +An instance of this ME is associated with an instance of the VP network CTP ME. The performance of upstream ATM flows is reported. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the VP network CTP. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +**Lost C = 0 + 1 cells:** This attribute counts all cell loss. It cannot distinguish between cells lost because of header bit errors, ATM-level header errors, cell policing, or buffer overflows. It records only loss of information, independent of the priority of the cell. (R) (mandatory) (2 bytes) + +**Lost C = 0 cells:** This attribute counts loss of high priority cells. It cannot distinguish between cells lost because of header bit errors, ATM-level header errors, cell policing, or buffer overflows. It records only loss of high priority cells. (R) (mandatory) (2 bytes) + +**Misinserted cells:** This attribute counts cells that are misrouted to a monitored VP. (R) (mandatory) (2 bytes) + +**Transmitted C = 0 + 1 cells:** This attribute counts cells originated by the transmitting end point (i.e., backward reporting is assumed). (R) (mandatory) (5 bytes) + +**Transmitted C = 0 cells:** This attribute counts high priority cells originated by the transmitting end point (i.e., backward reporting is assumed). (R) (mandatory) (5 bytes) + +**Impaired blocks:** This severely errored cell block counter is incremented whenever one of the following events takes place: the number of misinserted cells reaches its threshold; the number of bipolar violations reaches its threshold; or the number of lost cells reaches its threshold. Threshold values are based on vendor-operator negotiation. (R) (mandatory) (2 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | Lost CLP = 0 + 1 cells | 1 | +| 1 | Lost CLP = 0 cells | 2 | +| 2 | Misinserted cells | 3 | +| 3 | Impaired blocks | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### **9.13.11 Enhanced security control** + +This ME contains the capabilities, parameters and controls of enhanced G-PON security features when they are negotiated via the OMCI (Note). The attributes in this ME are intended to be used to implement a symmetric-key-based three step authentication process as described in the supplemental information section in the following. + +NOTE – If an ITU-T G.987 system uses 802.1X authentication as defined in [ITU-T G.987.3], the only applicable attribute of this ME is the broadcast key table. + +#### *Relationships* + +One instance of this ME is associated with the ONU ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is only one instance, number 0. (R) (mandatory) (2 bytes) + +**OLT crypto capabilities:** This attribute specifies the cryptographic mechanisms available at the OLT. It is written by the OLT during authentication step 1. It is formatted as a bit map, where a 1 bit indicates that the particular algorithm is supported, and a 0 bit indicates it is not supported. + +| Bit position | Algorithm | +|--------------|-------------------------------------| +| 1 (LSB) | AES-CMAC-128 (support is mandatory) | +| 2 | HMAC-SHA-256 | +| 3 | HMAC-SHA-512 | +| 4-128 | Reserved | + +(W) (mandatory) (16 bytes) + +**OLT random challenge table:** This attribute specifies the random challenge OLT\_challenge issued by the OLT during authentication step 1. It is structured as a table, with each entry being 17 bytes. The first byte is the table row number, starting at 1, and the remaining 16 bytes are the contents of the entry. OLT\_challenge is the concatenation of all 16 byte content fields. In normal use, the OLT will write all the entries in the table, and then trigger the ONU's processing of the entire table using the OLT challenge status attribute. The table size is known by the maximum index set by the OLT. The OLT can clear the table with a set operation to row 0. (R, W) (mandatory) ( $17 * N$ bytes) + +NOTE – It is assumed that the length of OLT\_challenge is always an integer multiple of 16 bytes. + +**OLT challenge status:** This Boolean attribute controls the completion of authentication step 1. This attribute behaves as follows. + +When the OLT performs the first of possibly several set operations to the OLT crypto capabilities or the OLT random challenge table attributes, a side effect of the set operation is that the ONU sets the OLT challenge status attribute to false. + +When the OLT completes the set operation(s) to the OLT crypto capabilities and the OLT random challenge table attributes, then it sets the OLT challenge status attribute to true. This triggers the ONU to process the OLT random challenge table, using its choice of the OLT's candidate cryptographic hash algorithms. + +The ONU initializes this attribute to the value false. (R, W) (mandatory) (1 byte) + +**ONU selected crypto capabilities:** This attribute specifies the cryptographic capability selected by the ONU in authentication step 2. Its value specifies one of the bit positions that has the value 1 in the OLT crypto capabilities attribute. (R) (mandatory) (1 byte) + +**ONU random challenge table:** This attribute specifies the random challenge ONU\_challenge issued by the ONU during authentication step 2. It is structured as a table, with each entry being 16 bytes of content. ONU\_challenge is the concatenation of all 16 byte content fields in the table. Once the OLT triggers a response to be generated using the OLT challenge status attribute, the ONU generates the response and writes the table (in a single operation). The AVC generated by this attribute signals to the OLT that the challenge is ready, so that the OLT can commence a get/get-next sequence to obtain the table's contents. (R) (mandatory) ( $16 * P$ bytes) + +**ONU authentication result table:** (authentication step 2). This attribute contains the result of the authentication computation from the ONU (ONU\_result), according to the ONU's selected crypto capabilities attribute. + +$$\text{ONU\_result} = \text{SelectedHashFunction}(\text{PSK}, (\text{ONU\_selected\_crypto capabilities} \mid \text{OLT\_challenge} \mid \text{ONU\_challenge} \mid 0x0000\ 0000\ 0000\ 0000)),$$ + +where "||" denotes concatenation. + +This attribute is structured as a table, with each entry being 16 bytes of content. The number of rows $Q$ is implicit in the choice of hash algorithm. + +Once the OLT triggers a response to be generated using the OLT challenge status attribute, the ONU generates ONU\_result and writes the table (in a single operation). The AVC generated by this attribute signals to the OLT that the + +response is ready, so that the OLT can commence a get/get-next sequence to obtain the table's contents. (R) (mandatory) ( $16 * Q$ bytes) + +**OLT authentication result table:** This attribute is used in authentication step 3. It contains OLT\_result, the result of the authentication computation from the OLT. + +$\text{OLT\_result} = \text{SelectedHashFunction} (\text{PSK}, (\text{ONU\_selected\_crypto\_capabilities} \mid \text{ONU\_challenge} \mid \text{OLT\_challenge} \mid \text{ONU\_serial\_number}))$ . + +The ONU\_serial\_number is the serial number attribute of the ONU-G ME, 8 bytes. + +This attribute is structured as a table, with each entry being 17 bytes. The first byte is the table row number, starting at 1; the remaining 16 bytes are content. OLT\_result is the concatenation of all 16 byte content fields. The OLT writes all entries into the table, and then triggers the ONU's processing of the table using the OLT result status attribute. The number of rows $R$ is implicit in the choice of hash algorithm. The OLT can clear the table with a set operation to row 0. (W) (mandatory) ( $17 * R$ bytes) + +**OLT result status:** (authentication step 3). This Boolean attribute controls and reports the status of the OLT authentication result table attribute. This attribute behaves as follows. + +When the OLT performs the first of possibly several set operations to the OLT authentication result table attribute, a side effect of the set operation is that the ONU sets the OLT result status attribute to false. + +When the OLT completes the set operation(s) to the OLT authentication result table, then it sets the OLT result status attribute to true. This triggers the ONU to process the OLT authentication result table. + +(R, W) (mandatory) (1 byte) + +**ONU authentication status:** This attribute indicates the status of the authentication relationship from the perspective of the ONU. It has the following values. + +- 0 Indeterminate. This initial value indicates that the OMCI authentication process has not yet completed, and may not even have been started. +- 1 Reserved. +- 2 Reserved. +- 3 Authentication success: the procedure has completed at least once since the latest ONU activation and in its most recent execution, the ONU has authenticated the OLT. +- 4 Authentication failure: the procedure has completed at least once since the latest ONU activation, and either its most recent execution resulted in an error or the ONU has failed to authenticate the OLT. +- 5 Reserved. + +Upon ONU activation, the ONU sets the attribute to the initial value. When the ONU authentication status has the value 3, encryption keys exchanged in the TC layer will be encrypted using the master session key (ITU-T G.984 systems) or the key encryption key (KEK, ITU-T G.987 systems). The OLT should check the value of this attribute before initiating a key switch. + +(R) (mandatory) (1 byte) + +**Master session key name:** Following successful authentication, this register contains the "name," or the hash signature, of the current master session key. The master session key is defined as: + +$$\text{MSK} = \text{SelectedHashFunction}(\text{PSK}, (\text{OLT\_challenge} \mid \text{ONU\_challenge})).$$ + +The master session key name is defined as: + +$$\text{MSKname} = \text{SelectedHashFunction}(\text{PSK}, (\text{ONU\_challenge} \mid \text{OLT\_challenge} \mid 0x\ 3141\ 5926\ 5358\ 9793\ 3141\ 5926\ 5358\ 9793)).$$ + +If the selected hash function generates more than 128 bits, the result is truncated to the leftmost (most significant) 128 bits. + +Upon the invalidation of a master session key (e.g., due to an ONU reset or deactivation, or due to an ONU-local decision that the master session key has expired), the ONU sets the master session key name to all zeros. (R) (mandatory) (16 bytes) + +**Broadcast key table:** This attribute is defined only in ITU-T G.987 systems. It contains the broadcast key generated by the OLT. It is a table, each of whose rows is structured as follows. + +**Row control** (1 byte): The two LSBs of this byte determine the attribute's behaviour under the set action. They always read back as 0 under the get next action. + +- 00 Set the specified row. +- 01 Clear the specified row. +- 10 Clear the entire table. +- 11 Reserved. + +The four MSBs specify the length of the fragment, which is left-justified in the key fragment field. The value 0 indicates 16 bytes of key fragment. + +The other two bits are reserved. + +**Row identifier** (1 byte): The two MSBs of this field are the key index, which appears in the header of encrypted multicast GEM frames. Key index 0 always indicates cleartext, and should therefore not appear in the identifier. The four LSBs identify the key fragment number, starting with 0. The other two bits are reserved. + +**Key fragment** (16 bytes): This field contains the specified fragment of the key (encrypted with AES-ECB using the KEK). + +(R, W) (optional) (18N bytes) + +**Effective key length:** This attribute specifies the maximum effective length, in bits, of keys generated by the ONU. (R) (optional) (2 bytes) + +#### *Actions* + +Get, set, get next + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|---------------------------------|----------------------------------------------------------------------------| +| 1..4 | Reserved | | +| 5 | ONU random challenge table | A new ONU challenge has been loaded into the table for the OLT to retrieve | +| 6 | ONU authentication result table | A new ONU response has been loaded into the table for the OLT to retrieve | +| 7..8 | Reserved | | +| 9 | ONU authentication status | The ONU authentication status has changed | +| 10..16 | Reserved | | + +##### Supplementary information + +This ME contains the facilities to perform a conventional three step hash-based authentication sequence found in [ISO/IEC 9798-4] (used in DSL systems that employ MS-CHAPv2 and elsewhere) using get and set messages. + +The logical structure of the conventional three step sequence is as follows. In the present situation, peer 1 is the OLT and peer 2 is the ONU. + +Message 1: (Peer 1 → peer 2) my\_cryptographic\_capabilities | random\_challenge\_1 + +Message 2: (Peer 2 → peer 1): selected\_cryptographic\_capabilities | random\_challenge\_2 | +MsgHash (PSK, (selected\_cryptographic\_capabilities | random\_challenge\_1 | +random\_challenge\_2, peer\_1\_identity)) + +Message 3: (Peer 1 → peer 2): MsgHash (PSK, (selected\_cryptographic\_capabilities | +random\_challenge\_2 | random\_challenge\_1 | peer\_2\_identity)) + +Where: + +MsgHash () is a keyed hash function of the message + +PSK is the pre-shared secret key known to the peers of the session + +Peer\_1\_identity is always "0x0000 0000 0000 0000" + +Peer\_2\_identity is the ONU serial number + +The prerequisite is the availability of a PSK. A PSK of 128 bits simplifies the application of security algorithms based on AES-128 (e.g., AES-CMAC-128). A PSK is associated with a particular ONU and is stored at that ONU and at the operator infrastructure. On the operator side, the PSK for a particular ONU might be stored in the physically connected OLT, or at a central server that the OLT accesses during authentication. Configuration of the PSK into the ONU and into the operator infrastructure may be done in any manner that satisfies these requirements. + +In the OMCI, the authentication message sequence follows the steps illustrated in Figure 9.13.11-1. + +![Sequence diagram showing the authentication message exchange between OLT and ONU. The diagram includes message exchanges like Set* [OLT crypto capabilities, OLT random challenge table], Set [OLT challenge status = true], AVC [ONU random challenge table], AVC [ONU authentication result table], Get [ONU selected crypto capabilities, ONU random challenge table, ONU authentication result table], Get_response [ ], Set* [OLT authentication result table], Set [OLT result status = true], AVC [ONU authentication state], Get [Master session key name], and Get_response [ ]. It also shows OMCI process states (S0, S1) and OLT challenge/result status (F, T).](806faec01366b8a02de54ed0de2b6a83_img.jpg) + +Notation: Set\* indicates multiple set operations, as needed to fill table + +| OLT | ONU | OMCI process states | OLT challenge/result status | +|-------------------------------------------------------------------------------------------------------|-----------------------------------------|---------------------|-----------------------------| +| Set* [OLT crypto capabilities, OLT random challenge table] → | | | | +| Set [OLT challenge status = true] → | | S0 | F | +| | ← AVC [ONU random challenge table] | | T | +| | ← AVC [ONU authentication result table] | | | +| Get [ONU selected crypto capabilities, ONU random challenge table, ONU authentication result table] → | | S1 | OLT result status | +| | ← Get_response [ ] | | | +| Set* [OLT authentication result table] → | | | | +| Set [OLT result status = true] → | | | F | +| | ← AVC [ONU authentication state] | | T | +| Get [Master session key name] → | | S0 | | +| | ← Get_response [ ] | | | + +G.988(10)\_F9.13.11-1 + +Sequence diagram showing the authentication message exchange between OLT and ONU. The diagram includes message exchanges like Set\* [OLT crypto capabilities, OLT random challenge table], Set [OLT challenge status = true], AVC [ONU random challenge table], AVC [ONU authentication result table], Get [ONU selected crypto capabilities, ONU random challenge table, ONU authentication result table], Get\_response [ ], Set\* [OLT authentication result table], Set [OLT result status = true], AVC [ONU authentication state], Get [Master session key name], and Get\_response [ ]. It also shows OMCI process states (S0, S1) and OLT challenge/result status (F, T). + +Figure 9.13.11-1 – Authentication message exchange sequence + +##### States of the OMCI authentication process + +When an ONU is in operation state O5, as defined in the respective TC layer specification, it maintains an OMCI authentication process state machine that tracks the phase of the authentication-related OMCI message flow exchange. The OMCI authentication process state machine is driven by the OLT challenge and result status indications, and generates output that indicates the ONU authentication status. + +![State diagram for the ONU authentication process. It shows two states: S0 - complete and S1 - OLT challenge pending. Transitions are triggered by OLT actions: 'OLT sets OLT crypto capabilities and/or OLT random challenge table' from S0 to S1, and 'OLT sets OLT result status' from S1 to S0.](1b8f775b754e09529388f10f6d4d31fe_img.jpg) + +``` + +stateDiagram-v2 + S0: S0 - complete + S1: S1 - OLT challenge pending + S0 --> S1 : OLT sets OLT crypto capabilities and/or OLT random challenge table + S1 --> S0 : OLT sets OLT result status + +``` + +G.988(12)\_F9.13.11-2 + +State diagram for the ONU authentication process. It shows two states: S0 - complete and S1 - OLT challenge pending. Transitions are triggered by OLT actions: 'OLT sets OLT crypto capabilities and/or OLT random challenge table' from S0 to S1, and 'OLT sets OLT result status' from S1 to S0. + +Figure 9.13.11-2 – ONU state diagram + +##### Synchronization with TC layer and security considerations (ITU-T G.984 systems only) + +When the ONU is in authenticated state, it uses its master session key to encrypt the key transmitted in the encryption\_key PLOAM message. + +The master session key is defined as: + +$$\text{MasterSessionKey} = \text{SelectedHashFunction} (\text{PSK}, (\text{OLT\_challenge} \mid \text{ONU\_challenge}))$$ + +where SelectedHashFunction () is the hash function selected by the ONU in the ONU selected crypto capabilities attribute from the list supplied by the OLT. + +The encryption of the encryption key is performed using AES-128 in electronic codebook (ECB) mode. + +Since the encryption key carried in the encryption key PLOAM message is not protected against forgery, there is the possibility that the key can be forged or replayed by an attacker. Both forged and replayed keys can be detected with key synchronization mechanisms. A replay attack, however, could force the OLT to use an old encryption key, which would violate the security requirements of downstream data encryption. Consequently, an OLT designed to resist a replay attack should ensure that the ONU does not send a previously used encryption key between authentication cycles. + +## 9.14 Mid-span passive optical network reach extender + +![Diagram of a Mid-span PON reach extender. On the left, two ONUs are connected to a central 'ODN: optical distribution network'. Each ONU has a 'UNI' interface on its left and an 'R/S' interface on its right. The 'ODN' connects to a 'Mid-span extender' via an 'S'/R'' interface. The 'Mid-span extender' connects to an 'OLT' via an 'R'/S'' interface and an 'OTL: optical trunk line'. The 'OLT' has an 'S/R' interface on its left and an 'SNI' interface on its right. A label 'G.988(12)_F9.14-1' is in the bottom right corner.](88e3971b31925e1d20fce1b6381fcabb_img.jpg) + +Diagram of a Mid-span PON reach extender. On the left, two ONUs are connected to a central 'ODN: optical distribution network'. Each ONU has a 'UNI' interface on its left and an 'R/S' interface on its right. The 'ODN' connects to a 'Mid-span extender' via an 'S'/R'' interface. The 'Mid-span extender' connects to an 'OLT' via an 'R'/S'' interface and an 'OTL: optical trunk line'. The 'OLT' has an 'S/R' interface on its left and an 'SNI' interface on its right. A label 'G.988(12)\_F9.14-1' is in the bottom right corner. + +Figure 9.14.1 – Mid-span PON reach extender + +[ITU-T G.984.6] defines a mid-span PON RE. An RE may extend more than one PON, using optical amplification (OA) or optical-electrical-optical (OEO) regeneration technology. For easy reference, Figure 9.14-1 illustrates the interface designations. + +The RE model includes one built-in ONU, which serves for management of the RE itself, as well as for optional subscriber or craft UNIs. The ONU embedded within the RE is therefore able to use any of the MEs defined elsewhere in this Recommendation, including the ANI-G and T-CONT MEs, which represent the built-in ONU's individual uplink. + +NOTE 1 – Although the built-in management ONU is physically contained within physical RE equipment, the management model perspective is that the ONU software controls the entire equipment. In terms of the model, therefore, the management ONU contains the RE equipment and functionality. + +This clause defines additional MEs that pertain to the RE function separately. + +The current scope of the RE model includes the use of either OEO regeneration or OA in the upstream and downstream directions, independently. Split ratio enhancement (more than one RE UNI for every RE ANI) is also included. This results in eight possible arrangements, are listed in the following tables. + +NOTE 2 – Each amplifier ME is associated with an RE common amplifier parameters ME. + +| Downstream technology | Upstream technology | Internal optical split | Model | +|-----------------------|---------------------|------------------------|-------------------------------------------------------------------| +| OEO | OEO | 1:1 | One PPTP RE UNI pointing to one RE ANI-G, all attributes active | +| OEO | OEO | 1:N | N PPTP RE UNIs pointing to one RE ANI-G, all attributes active | +| OA | OA | 1:1 | One RE upstream amplifier pointing to one RE downstream amplifier | +| OA | OA | 1:N | N RE upstream amplifiers pointing to one RE downstream amplifier | + +| Downstream technology | Upstream technology | Internal optical split | Model | +|-----------------------|---------------------|------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| OA | OEO | 1:1 | One PPTP RE UNI pointing to one RE ANI-G. Downstream transmit optical attributes of the RE ANI-G not used. One downstream amplifier, likely sharing ME ID with the RE ANI-G. | +| OA | OEO | 1:N | N PPTP RE UNIs pointing to one RE ANI-G. Downstream transmit optical attributes of the RE ANI-G not used. One downstream amplifier, likely sharing ME ID with the RE ANI-G. | +| OEO | OA | 1:1 | One PPTP RE UNI pointing to one RE ANI-G. Upstream transmit optical attributes of the RE UNI not used. One upstream amplifier, likely sharing ME ID with the PPTP RE UNI. | +| OEO | OA | 1:N | N PPTP RE UNIs pointing to one RE ANI-G. Upstream transmit optical attributes of the RE UNI not used. N upstream amplifiers, likely sharing ME IDs with the PPTP RE UNIs. | + +### 9.14.1 RE ANI-G + +This ME organizes data associated with each R' / S' physical interface of an RE if the RE supports OEO regeneration in either direction. The management ONU automatically creates one instance of this ME for each R'/S' physical port (uni- or bidirectional) as follows. + +- When the RE has mid-span PON RE ANI interface ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the mid-span PON RE ANI type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the mid-span PON RE ANI type. Note that the installation of a plug-and-play card may indicate the presence of a mid-span PON RE ANI port via equipment ID as well as its type attribute, and indeed may cause the management ONU to instantiate a port-mapping package to specify the ports precisely. + +The management ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a mid-span PON RE ANI circuit pack, nor is it equipped with a mid-span PON RE ANI circuit pack. + +As illustrated in Figure 8.2.10-4, an RE ANI-G may share the physical port with an RE downstream amplifier. The ONU declares a shared configuration through the port-mapping package combined port table, whose structure defines one ME as the master. It is recommended that the RE ANI-G be the master, with the RE downstream amplifier as a secondary ME. + +The administrative state, operational state and ARC attributes of the master ME override similar attributes in secondary MEs associated with the same port. In the secondary ME, these attributes are present, but cause no action when written and have undefined values when read. The RE downstream amplifier should use its provisionable downstream alarm thresholds and should declare downstream alarms as necessary; other isomorphic alarms should be declared by the RE ANI-G. The test action should be addressed to the master ME. + +#### Relationships + +An instance of this ME is associated with each R'/S' physical interface of an RE that includes OEO regeneration in either direction, and with one or more instances of the PPTP RE UNI. It may also be associated with an RE downstream amplifier. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value indicates the physical position of the R'/S' interface. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID. (R) (mandatory) (2 bytes) + +NOTE 1 – This ME ID may be identical to that of an RE downstream amplifier if it shares the same physical slot and port. + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +NOTE 2 – When an RE supports multiple PONs, or protected access to a single PON, its primary ANI-G cannot be completely shut down, due to a loss of the management communications capability. Complete blocking of service and removal of power may nevertheless be appropriate for secondary RE ANI-Gs. Administrative lock suppresses alarms and notifications for an RE ANI-G, be it either primary or secondary. + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Optical signal level:** This attribute reports the current measurement of total downstream optical power. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) (R) (optional) (2 bytes) + +**Lower optical threshold:** This attribute specifies the optical level that the RE uses to declare the downstream low received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper optical threshold:** This attribute specifies the optical level that the RE uses to declare the downstream high received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Transmit optical level:** This attribute reports the current measurement of mean optical launch power. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) (R) (optional) (2 bytes) + +**Lower transmit power threshold:** This attribute specifies the minimum mean optical launch power that the RE uses to declare the low transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper transmit power threshold:** This attribute specifies the maximum mean optical launch power that the RE uses to declare the high transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Usage mode:** In a mid-span PON RE, an R'/S' interface may be used as the PON interface for the embedded management ONU or the uplink interface for an S'/R' interface. This attribute specifies the usage of the R'/S' interface. (R, W) (mandatory) (1 byte) + +- 0 Disable +- 1 This R'/S' interface is used as the uplink for the embedded management ONU +- 2 This R'/S' interface is used as the uplink for one or more PTP RE UNI(s) +- 3 This R'/S' interface is used as the uplink for both the embedded management ONU and one or more PTP RE UNI(s) (in a time division fashion). + +**Target upstream frequency:** This attribute specifies the frequency of the converted upstream signal on the optical trunk line (OTL), in gigahertz. The converted frequency must conform to the frequency plan specified in [ITU-T G.984.6]. The value 0 means that the upstream signal frequency remains the same as the original frequency; no frequency conversion is done. If the RE does not support provisionable upstream frequency (wavelength), this attribute should take the fixed value representing the RE's capability and the RE should deny attempts to set the value of the attribute. If the RE does support provisionable upstream frequency conversion, the default value of this attribute is 0. (R, W) (optional) (4 bytes). + +**Target downstream frequency:** This attribute specifies the frequency of the downstream signal received by the RE on the OTL, in gigahertz. The incoming frequency must conform to the frequency plan specified in [ITU-T G.984.6]. The default value 0 means that the downstream frequency remains the same as its original frequency; no frequency conversion is done. If the RE does not support provisionable downstream frequency selectivity, this attribute should take the fixed value representing the RE's capability, and the RE should deny attempts to set the value of the attribute. If the RE does support provisionable downstream frequency selectivity, the default value of this attribute is 0. (R, W) (optional) (4 bytes). + +**Upstream signal transmission mode:** When true, this Boolean attribute enables conversion from burst mode to continuous mode. The default value false specifies burst mode upstream transmission. If the RE does not have the ability to convert from burst to continuous mode transmission, it should deny attempts to set this attribute to true. (R, W) (optional) (1 byte) + +#### Actions + +Get, set + +Test Test the RE-ANI. The test action can be used to perform optical line supervision tests; refer to the test and test result message definitions in Annex A. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of RE ANI-G | + +##### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------------| +| 3 | ARC | Alarm-reporting control cancellation | +| 4..14 | N/A | | +| 15..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------------------------|------------------------------------------------------------------------------------| +| 0 | Low received optical power | Received downstream optical power below threshold | +| 1 | High received optical power | Received downstream optical power above threshold | +| 2 | Low transmit optical power | Transmitted upstream optical power below lower threshold | +| 3 | High transmit optical power | Transmitted upstream optical power above upper threshold | +| 4 | High laser bias current | Laser bias current above threshold determined by vendor; laser end of life pending | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +Test result: The RE may report a test result autonomously if it performs self-test functions autonomously. + +### 9.14.2 Physical path termination point RE UNI + +This ME represents an S'/R' interface in a mid-span PON RE that supports OEO regeneration in at least one direction, where physical paths terminate and physical path level functions are performed (transmit or receive). + +Such an RE automatically creates an instance of this ME for each S'/R' interface port as follows. + +- When the RE has mid-span PON RE UNI interface ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the mid-span PON RE UNI type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the mid-span PON RE UNI type. Note that the installation of a plug-and-play card may indicate the presence of a mid-span PON RE UNI port via equipment ID as well as its type attribute, and indeed may cause the management ONU to instantiate a port-mapping package to specify the ports precisely. + +The management ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a mid-span PON RE UNI circuit pack, nor is it equipped with a mid-span PON RE UNI circuit pack. + +As illustrated in Figure 8.2.10-3, a PPTP RE UNI may share the physical port with an RE upstream amplifier. The ONU declares a shared configuration through the port-mapping package combined port table, whose structure defines one ME as the master. It is recommended that the PPTP RE UNI be the master, with the RE upstream amplifier as a secondary ME. + +The administrative state, operational state and ARC attributes of the master ME override similar attributes in secondary MEs associated with the same port. In the secondary ME, these attributes are present, but cause no action when written and have undefined values when read. The RE upstream amplifier should use its provisionable upstream alarm thresholds and should declare upstream alarms + +as necessary; other isomorphic alarms should be declared by the PPTP RE UNI. The test action should be addressed to the master ME. + +#### *Relationships* + +An instance of this ME is associated with each instance of a mid-span PON RE S'/R' physical interface of an RE that includes OEO regeneration in either direction, and it may also be associated with an RE upstream amplifier. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number indicates the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with the range 1..255. (R) (mandatory) (2 bytes) + +NOTE 1 – This ME ID may be identical to that of an RE upstream amplifier if it shares the same physical slot and port. + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +NOTE 2 – Administrative lock of a PPTP RE UNI results in loss of signal to any downstream ONUs. + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**RE ANI-G pointer:** This attribute points to an RE ANI-G instance. (R, W) (mandatory) (2 bytes) + +**Total optical receive signal level table:** This table attribute reports a series of measurements of time averaged received upstream optical signal power. The measurement circuit should have a temporal response similar to a simple 1 pole low pass filter, with an effective time constant of the order of a GTC frame time. Each table entry has a 2 byte frame counter field (most significant end), and a 2 byte power measurement field. The frame counter field contains the least significant 16 bits of the superframe counter received closest to the time of the measurement. The power measurement field is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) The RE equipment should add entries to this table as frequently as is reasonable. The RE should clear the table once it is read by the OLT. (R) (optional) (4 \* *N* bytes, where *N* is the number of measurements present.) + +**Per burst receive signal level table:** This table attribute reports the most recent measurement of received burst upstream optical signal power. Each table entry has a 2 byte ONU-ID field (most significant end), and a 2 byte power measurement field. The power measurement field is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) (R) (optional) (4 \* *N* bytes, where *N* is the number of distinct ONUs connected to the S'/R' interface.) + +**Lower receive optical threshold:** This attribute specifies the optical level that the RE uses to declare the burst mode low received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper receive optical threshold:** This attribute specifies the optical level that the RE uses to declare the burst mode high optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Transmit optical level:** This attribute reports the current measurement of the downstream mean optical launch power. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (R) (optional) (2 bytes) + +**Lower transmit power threshold:** This attribute specifies the downstream minimum mean optical launch power at the S'/R' interface that the RE uses to declare the low transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper transmit power threshold:** This attribute specifies the downstream maximum mean optical launch power at the S'/R' interface that the RE uses to declare the high transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Additional preamble:** This attribute indicates the number of bytes of PLOu preamble that are unavoidably consumed while passing the RE. (R) (mandatory) (1 byte) + +**Additional guard time:** This attribute indicates the number of bytes of extra guard time that are needed to ensure correct operation with the RE. (R) (mandatory) (1 byte) + +**Connected ONUs table:** s attribute is used to pass ONU ID information of the connected ONUs per RE UNI. The get, get next sequence must be used with this attribute since its size is unspecified. Upon ME instantiation, this attribute is an empty list. + +Each entry contains: + +– ONU ID (2 bytes) + +(R) (optional) (2N bytes, where N is the number of ONUs) + +**Clear ONU table:** the attribute is used to notify RE to clear the entire Connected ONUs table by OLT. The OLT must insure that the ONU IDs have been retrieved before clearing the table, or loss of data may occur. + +When the value of the byte is set to 1, the RE clears the entire Connected ONUs table and resets the byte to 0. + +(W) (optional) (1 byte) + +#### *Actions* + +Get, get next, set + +Test Test the PPTP RE UNI. The test action can be used to perform optical line supervision tests; refer to the test and test result message definitions in Annex A. + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of PPTP RE UNI | +| 3 | ARC | ARC timer expiration | +| 4..14 | N/A | | +| 15..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------------------------|------------------------------------------------------------------------------------------| +| 0 | Low received optical power | Received upstream optical power of one or more ONUs below threshold | +| 1 | High received optical power | Received upstream optical power of one or more ONUs above threshold | +| 2 | Low transmit optical power | Transmit downstream optical power below lower threshold | +| 3 | High transmit optical power | Transmit downstream optical power above upper threshold | +| 4 | High laser bias current | Laser bias current above threshold determined by vendor; laser end of life pending | +| 5 | S'/R' LOS | S'/R' LOS detected. No optical signal received at the S'/R' upstream interface in 500 µs | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +### 9.14.3 RE upstream amplifier + +This ME organizes data associated with each upstream RE optical amplifier (OA) supported by the RE. The management ONU automatically creates one instance of this ME for each upstream OA as follows. + +- When the RE has mid-span PON RE upstream OA ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the mid-span PON RE upstream OA type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the mid-span PON RE upstream OA type. Note that the installation of a plug-and-play card may indicate the presence of a mid-span PON RE upstream OA via equipment ID as well as its type attribute, and indeed may cause the management ONU to instantiate a port-mapping package to specify the ports precisely. + +The management ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a mid-span PON RE upstream OA circuit pack, nor is it equipped with a mid-span PON RE upstream OA circuit pack. + +#### Relationships + +An instance of this ME is associated with an upstream OA, and with an instance of a circuit pack. If the RE includes OEO regeneration in either direction, the RE upstream amplifier is also associated with a PPTP RE UNI. Refer to clause 9.14.2 for further discussion. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value indicates the physical position of the upstream OA. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID. (R) (mandatory) (2 bytes) + +NOTE 1 – This ME ID may be identical to that of a PPTP RE UNI if it shares the same physical slot and port. + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +NOTE 2 – Administrative lock of an RE upstream amplifier results in LOS from any downstream ONUs. + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Operational mode:** This attribute indicates the operational mode as follows. + +- 0 Constant gain +- 1 Constant output power +- 2 Autonomous + +(R, W) (mandatory) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**RE downstream amplifier pointer:** This attribute points to an RE downstream amplifier instance. The default value is 0xFFFF, a null pointer. (R, W) (mandatory) (2 bytes) + +**Total optical receive signal level table:** This table attribute reports a series of measurements of time-averaged input upstream optical signal power. The measurement circuit should have a temporal response similar to a simple 1 pole low pass filter, with an effective time constant on the order of a GTC frame time. Each table entry has a 2 byte frame counter field (most significant end), and a 2 byte power measurement field. The frame counter field contains the least significant 16 bits of the superframe counter received closest to the time of the measurement. The power measurement field is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) The RE equipment should add entries to this table as frequently as is reasonable. The RE should clear the table once it is read by the OLT. (R) (optional) (4 \* *N* bytes, where *N* is the number of measurements present.) + +**Per burst receive signal level table:** This table attribute reports the most recent measurement of received burst upstream optical signal power. Each table entry has a 2 byte ONU-ID field (most significant end), and a 2 byte power measurement field. The power measurement field is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding -32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) (R) (optional) (4 \* *N* bytes, where *N* is the number of distinct ONUs connected to the S'/R' interface.) + +**Lower receive optical threshold:** This attribute specifies the optical level that the RE uses to declare the low received optical power alarm. Valid values are -127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper receive optical threshold:** This attribute specifies the optical level that the RE uses to declare the high received optical power alarm. Valid values are -127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Transmit optical signal level:** This attribute reports the current measurement of the mean optical launch power of the upstream OA. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (R) (optional) (2 bytes) + +**Lower transmit optical threshold:** This attribute specifies the minimum mean optical launch power that the RE uses to declare the low transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper transmit optical threshold:** This attribute specifies the maximum mean optical launch power that the RE uses to declare the high transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +#### *Actions* + +Get, get next, set + +Test Test the upstream amplifier. The test action can be used to perform optical line supervision tests; refer to the test and test result message descriptions in Annex A. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|--------------------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of RE upstream amplifier | +| 3 | N/A | | +| 4 | ARC | Alarm-reporting control cancellation | +| 5..13 | N/A | | +| 14..16 | Reserved | | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-----------------------------|------------------------------------------------------------------------------------------| +| 0 | Low received optical power | Received upstream optical power of one or more ONUs below threshold | +| 1 | High received optical power | Received upstream optical power of one or more ONUs above threshold | +| 2 | Low transmit optical power | Transmit upstream optical power below lower threshold | +| 3 | High transmit optical power | Transmit upstream optical power above upper threshold | +| 4 | High laser bias current | Laser bias current above threshold determined by vendor; laser end of life pending | +| 5 | S'/R' LOS | S'/R' LOS detected. No optical signal received at the S'/R' upstream interface in 500 µs | +| 6..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +**Test result:** The RE may report a test result autonomously if it performs self-test functions autonomously. + +### 9.14.4 RE downstream amplifier + +This ME organizes data associated with each OA for downstream data supported by the RE. The management ONU automatically creates one instance of this ME for each downstream OA as follows. + +- When the RE has mid-span PON RE downstream OA ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of the mid-span PON RE downstream OA type. +- When a cardholder provisioned for plug-and-play is equipped with a circuit pack of the mid-span PON RE downstream OA type. Note that the installation of a plug-and-play card may indicate the presence of a mid-span PON RE downstream OA via equipment ID as well as its type attribute, and indeed may cause the management ONU to instantiate a port-mapping package to specify the ports precisely. + +The management ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a mid-span PON RE downstream OA circuit pack, nor is it equipped with a mid-span PON RE downstream OA circuit pack. + +#### Relationships + +An instance of this ME is associated with a downstream OA and with an instance of a circuit pack. If the RE includes OEO regeneration in either direction, the RE downstream amplifier is also associated with an RE ANI-G. Refer to clause 9.14.1 for further discussion. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Its value indicates the physical position of the downstream OA. The first byte is the slot ID (defined in clause 9.1.5 of [ITU-T G.984.4]). The second byte is the port ID. (R) (mandatory) (2 bytes) + +NOTE 1 – This ME ID may be identical to that of an RE ANI-G if it shares the same physical slot-port. + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +NOTE 2– When an RE supports multiple PONs, or protected access to a single PON, its primary ANI-G cannot be completely shut down, due to a loss of the management communications capability. Complete blocking of service and removal of power may nevertheless be appropriate for secondary RE ANI-Gs. Administrative lock suppresses alarms and notifications for both primary and secondary RE ANI-Gs. Administrative lock suppresses alarms and notifications for an RE downstream amplifier, be it either primary or secondary. + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**ARC:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**ARC interval:** See clause A.1.4.3. (R, W) (optional) (1 byte) + +**Operational mode:** This attribute indicates the operational mode as follows. + +- 0 Constant gain +- 1 Constant output power +- 2 Autonomous + +(R,W) (mandatory) (1 byte) + +**Input optical signal level:** This attribute reports the current measurement of the input optical signal power of the downstream OA. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) (R) (optional) (2 bytes) + +**Lower input optical threshold:** This attribute specifies the optical level the RE uses to declare the low received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper input optical threshold:** This attribute specifies the optical level the RE uses to declare the high received optical power alarm. Valid values are –127 dBm (coded as 254) to 0 dBm (coded as 0) in 0.5 dB increments. The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Output optical signal level:** This attribute reports the current measurement of the mean optical launch power of the downstream OA. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.002 dB granularity. (Coding –32768 to +32767, where 0x00 = 0 dBm, 0x03e8 = +2 dBm, etc.) (R) (optional) (2 bytes) + +**Lower output optical threshold:** This attribute specifies the minimum mean optical launch power that the RE uses to declare the low transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**Upper output optical threshold:** This attribute specifies the maximum mean optical launch power that the RE uses to declare the high transmit optical power alarm. Its value is a 2s complement integer referred to 1 mW (i.e., dBm), with 0.5 dB granularity. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) + +**R'S' splitter coupling ratio:** This attribute reports the coupling ratio of the splitter at the R'S' interface that connects the embedded management ONU and the amplifiers to the OTL. Valid values are 99:1 (coded as 99 decimal) to 1:99 (coded as 1 decimal), where the first value is the value encoded and is the percentage of the optical signal connected to the amplifier. The default value 0xFF indicates that there is no splitter connected to this upstream/downstream amplifier pair. (R) (optional) (1 byte) + +#### *Actions* + +##### **Get, set** + +**Test** Test the RE downstream amplifier. The test action can be used to perform optical line supervision tests; refer to the test and test result message descriptions in Annex A. + +#### *Notifications* + +#### **Attribute value change** + +| Number | Attribute value change | Description | +|--------|------------------------|----------------------------------------------| +| 1 | N/A | | +| 2 | Op state | Operational state of RE downstream amplifier | +| 3 | ARC | Alarm-reporting control cancellation | +| 4..12 | N/A | | +| 13..16 | Reserved | | + +##### **Alarm** + +| Alarm number | Alarm | Description | +|--------------|-----------------------------|------------------------------------------------------------------------------------| +| 0 | Low received optical power | Received downstream optical power below threshold | +| 1 | High received optical power | Received downstream optical power above threshold | +| 2 | Low transmit optical power | Transmit downstream optical power below lower threshold | +| 3 | High transmit optical power | Transmit downstream optical power above upper threshold | +| 4 | High laser bias current | Laser bias current above threshold determined by vendor; laser end of life pending | +| 5..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +**Test result:** The RE may report a test result autonomously if it performs self-test functions autonomously. + +### **9.14.5 RE config portal** + +The RE config portal ME provides a way for the OLT to discover the configuration delivered to an RE by a non-OMCI configuration method (SNMP, etc.). Text retrieved from this ME is not required to be understood by the OLT or EMS, but it may be useful for human or vendor-specific analysis tools. + +An instance of this ME may be created by an RE that supports non-OMCI RE configuration. It is not reported during an MIB upload. + +#### Relationships + +One instance of this ME is associated with an instance of a TCP/UDP config data ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. There is one instance, number 0. (R) (mandatory) (2 bytes) + +**Configuration text table:** This attribute is used to pass a textual representation of the RE configuration back to the OLT. The contents are vendor-specific. The get, get next sequence must be used with this attribute since its size is unspecified. Upon ME instantiation, the management ONU sets this attribute to 0. (R) (mandatory) (x bytes) + +**TCP/UDP pointer:** This pointer associates the RE config portal with the TCP/UDP config data ME to be used for communication with any valid and necessary in-band protocol server. The default value is 0xFFFF. (R, W) (mandatory) (2 bytes) + +#### Actions + +Get, get next + +#### Notifications + +#### Attribute value change + +| Number | Attribute value change | Description | +|--------|------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | Configuration text | Indicates an update to the RE configuration from a non-OMCI interface. Because the attribute is a table, the AVC does not contain information about its value. The OLT must use the get, get next action sequence if it wishes to obtain the updated attribute content. | +| 2 | N/A | | +| 3..16 | Reserved | | + +### 9.14.6 RE common amplifier parameters + +This ME organizes data associated with each OA supported by the RE. The management ONU automatically creates one instance of this ME for each upstream or downstream OA. + +#### Relationships + +An instance of this ME is associated with an instance of the RE downstream amplifier or RE upstream amplifier ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of an upstream or downstream OA. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID. (R) (mandatory) (2 bytes) + +NOTE – The type of the linked ME can be determined by uniqueness of slot and port. + +**Gain:** This attribute reports the current measurement of the OA's gain, in decibels. Its value is a 2s complement integer with 0.25 dB granularity, and with a range from –32 dB to 31.5 dB. The value 0x7F indicates that the current measured gain is 0, i.e., negative infinity in decibels terms. (R) (optional) (1 byte) + +- Lower gain threshold:** This attribute specifies the gain the RE uses to declare the low gain alarm. Valid values are 0 dB (coded as 0x00) to 63.5 dB (coded as 0xFE). The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) +- Upper gain threshold:** This attribute specifies the gain the RE uses to declare the high gain alarm. Valid values are 0 dB (coded as 0x00) to 63.5 dB (coded as 0xFE). The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) +- Target gain:** This attribute specifies the target gain, when the operational mode of the parent RE downstream or upstream amplifier is set to constant gain mode. Valid values are 0 dB (coded as 0x00) to 63.5 dB (coded as 0xFE). The default value 0xFF selects the RE's internal policy. (R, W) (optional) (1 byte) +- Device temperature:** This attribute reports the temperature in degrees Celsius of the active device (SOA or pump) in the OA. Its value is a 2s complement integer with granularity 1/256 °C. (R) (optional) (2 bytes) +- Lower device temperature threshold:** This attribute is a 2s complement integer that specifies the temperature the RE uses to declare the low temperature alarm. Valid values are –64 to +63 °C in 0.5 °C increments. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) +- Upper device temperature threshold:** This attribute is a 2s complement integer that specifies the temperature the RE uses to declare the high temperature alarm. Valid values are –64 to +63 °C in 0.5 °C increments. The default value 0x7F selects the RE's internal policy. (R, W) (optional) (1 byte) +- Device bias current:** This attribute contains the measured bias current applied to the SOA or pump laser. Its value is an unsigned integer with granularity 2 mA. Valid values are 0 to 512 mA. (R) (optional) (1 byte) +- Amplifier saturation output power:** This attribute reports the saturation output power of the amplifier as specified by the manufacturer. Its value is an unsigned integer referred to 1 mW (i.e., dBm), with 0.1 dB granularity. (R) (optional) (2 bytes) +- Amplifier noise figure:** This attribute reports the intrinsic noise figure of the amplifier, as specified by the manufacturer. Its value is an unsigned integer with 0.1 dB granularity (R) (optional) (1 byte) +- Amplifier saturation gain:** This attribute reports the gain of the amplifier at saturation, as specified by the manufacturer. Its value is an unsigned integer with 0.25 dB granularity, and with a range from 0 to 63.75 dB. (R) (optional) (1 byte) + +#### Actions + +Get, set + +#### Notifications + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|-------------------|--------------------------------------------------------------------------------------| +| 0 | Low gain | Gain below lower threshold | +| 1 | High gain | Gain above upper threshold | +| 2 | Low temperature | Device temperature below lower threshold | +| 3 | High temperature | Device temperature above upper threshold | +| 4 | High bias current | Device bias current above threshold determined by vendor; device end of life pending | + +##### Alarm + +| Alarm number | Alarm | Description | +|--------------|---------------------------|----------------------------------------------------------------------------------| +| 5 | High temperature shutdown | Device has shut down due to temperature exceeding manufacturer's specifications | +| 6 | High current shutdown | Device has shut down due to bias current exceeding manufacturer's specifications | +| 7..207 | Reserved | | +| 208..223 | Vendor-specific alarms | Not to be standardized | + +## 9.15 RS232/RS485 interface service + +This clause defines MEs associated with RS232/RS485 UNI, as shown in Figure 9.15-1. + +![Diagram showing managed entities associated with RS232/RS485 UNI. A central box '9.15.2 RS232/RS485 Port operation configuration data' is connected to 'Ipv4 or IPv6 host configuration data', 'TCP/UDP configuration data', and '9.15.1 PPTP RS232/RS485 UNI'. '9.15.1 PPTP RS232/RS485 UNI' is further connected to '9.15.3 RS232/RS485 PM history data'. An external arrow points to 'Ipv4 or IPv6 host configuration data' with the text 'Pointed to by MAC bridge port configuration data'.](d7c887af401c0d5aeb229da743f115bd_img.jpg) + +``` + +graph TD + A[Pointed to by MAC bridge port configuration data] --> B[Ipv4 or IPv6 host configuration data] + B <--> C[9.15.2 RS232/RS485 Port operation configuration data] + C --> D[TCP/UDP configuration data] + C --> E[9.15.1 PPTP RS232/RS485 UNI] + E --> F[9.15.3 RS232/RS485 PM history data] + +``` + +G.988(12)-Amd.1(14)\_F9.15-1 + +Diagram showing managed entities associated with RS232/RS485 UNI. A central box '9.15.2 RS232/RS485 Port operation configuration data' is connected to 'Ipv4 or IPv6 host configuration data', 'TCP/UDP configuration data', and '9.15.1 PPTP RS232/RS485 UNI'. '9.15.1 PPTP RS232/RS485 UNI' is further connected to '9.15.3 RS232/RS485 PM history data'. An external arrow points to 'Ipv4 or IPv6 host configuration data' with the text 'Pointed to by MAC bridge port configuration data'. + +Figure 9.15-1 – Managed entities associated with RS232/RS485 UNI + +### 9.15.1 Physical path termination point RS232/RS485 UNI + +This ME represents an RS232/RS485 UNI in the ONU, where physical paths terminate and physical path level functions are performed. + +The ONU automatically creates an instance of this ME per port as follows. + +- When the ONU has RS232/RS485 ports built into its factory configuration. +- When a cardholder is provisioned to expect a circuit pack of RS232/RS485 type. +- When a cardholder provisioned for plug and play is equipped with a circuit pack of RS232/RS485 type. Note that the installation of a plug and play card may indicate the presence of RS232/RS485 ports via equipment ID as well as its type, and indeed may cause the ONU to instantiate a port-mapping package that specifies RS232/RS485 ports. + +The ONU automatically deletes instances of this ME when a cardholder is neither provisioned to expect a RS232/RS485 circuit pack, nor is equipped with a RS232/RS485 circuit pack. + +#### Relationships + +An instance of this ME is associated with each real RS232/RS485 port. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number is directly associated with the physical position of the UNI. The first byte is the slot ID (defined in clause 9.1.5). The second byte is the port ID, with range 1..255. (R) (mandatory) (2 bytes) + +**Administrative state:** This attribute locks (1) and unlocks (0) the functions performed by this ME. Administrative state is further described in clause A.1.6. (R, W) (mandatory) (1 byte) + +**Operational state:** This attribute indicates whether the ME is capable of performing its function. Valid values are enabled (0) and disabled (1). (R) (optional) (1 byte) + +**Port mode:** This attribute indicates the working mode of the RS232/RS485 controller chipset. Valid values are as follows. + +- 0 half-duplex +- 1 full duplex + +(mandatory) (1 byte) + +**Baud\_rate:** This attribute specifies the working baud rate of RS232/RS485 port. Valid values are as follows. + +- 0 300 bit/s +- 1 600 bit/s +- 2 1200 bit/s +- 3 2400 bit/s +- 4 4800 bit/s +- 5 9600 bit/s +- 6 19200 bit/s +- 7 38400 bit/s +- 8 43000 bit/s +- 9 56000 bit/s +- 10 57600 bit/s +- 11 115200 bit/s + +(R, W, set-by-create) (mandatory) (1 byte) + +**Data\_bits:** This attribute specifies the bits of the data. Valid values are as follows. + +- 5 5 bits +- 6 6 bits +- 7 7 bits +- 8 8 bits + +(R, W, set-by-create) (mandatory) (1 byte) + +**Parity:** This attribute specifies the parity of the data. Valid values are as follows. + +- 0 no parity +- 1 odd parity +- 2 even parity + +(R, W, set-by-create) (mandatory) (1 byte) + +**Stop\_bits:** This attribute specifies the number of stop bits of the data. Valid values are as follows. + +- 1 1 bit +- 2 2 bits + +(R, W, set-by-create) (mandatory) (1 byte) + +**Flow\_control:** This attribute specifies the flow control of the data. Valid values are as follows. + +- 0 no flow control +- 1 hardware flow control (RTS/CTS) +- 2 software flow control (Xon/Xoff) + +(R, W, set-by-create) (mandatory) (1 byte) + +**Min\_send\_payload:** This attribute specifies the length of serial data acquisition by RS232/RS485 controller chipset in the fixed length mode. (R) (mandatory) (4 bytes) + +**Min\_send\_time:** This attribute specifies the time of serial data acquisition by RS232/RS485 controller chipset in the timing mode. (R) (mandatory) (4 bytes) + +**Reserve:** This attribute is reserved for future use. + +#### *Actions* + +Get, set + +### 9.15.2 RS232/RS485 port operation configuration data + +This ME specifies the RS232/RS485 port operation mode. The ONU automatically creates instances of this ME if RS232/RS485 data acquisition services are available. + +#### *Relationships* + +An instance of this ME is associated with a TCP/UDP config data ME and a PPTP RS232/RS485 UNI. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. (R, set-by-create) (mandatory) (2 bytes) + +**Socket mode:** This attribute identifies the RS232/RS485 port operation mode as follows: +0x00 TCP/server mode; +0x01 TCP/client mode; +0x02 UDP mode, +Other values are reserved. +(R) (mandatory) (1 byte) + +**TCP/UDP pointer:** This pointer associates the RS232/RS485 port operation configuration with the TCP/UDP config data ME to be used for communication with the serial server. The default value is 0xFFFF, a null pointer. (R, W) (mandatory) (2 bytes) + +**PPTP pointer:** This attribute points to the PPTP RS232/RS485 UNI ME that serves the serial data acquisition function. (R, W, set-by-create) (mandatory) (2 bytes) + +### 9.15.3 RS232/RS485 performance monitoring history data + +This ME collects PM data for a RS232/RS485 interface. Instances of this ME are created and deleted by the OLT. + +#### *Relationships* + +An instance of this ME is associated with an instance of the PPTP RS232/RS485 UNI ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the PPTP RS232/RS485 UNI. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 id:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Incoming bytes from PON port:** This attribute counts the bytes received on the PON port. (R) (optional) (4 bytes) + +**Outgoing bytes from PON port:** This attribute counts the bytes transmitted on the PON port. (R) (optional) (4 bytes) + +**Incoming bytes from RS232/RS485 controller chipset:** This attribute counts the bytes received on the RS232/RS485 chipset. (R) (optional) (4 bytes) + +**Outgoing bytes from RS232/RS485 controller chipset:** This attribute counts the bytes transmitted on the RS232/RS485 chipset. (R) (optional) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +#### *Notifications* + +#### **Threshold crossing alert** + +| Number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------|--------------------------|-----------------------------------------| +| 1 | Incoming packets | 1 | +| 2 | Incoming bits | 2 | +| 3 | Outgoing packets | 3 | +| 4 | Outgoing bits | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +## **9.16 ITU-T G.989.3 TWDM and ITU-T G.9804.2 TWDM/TDM PON** + +This clause defines MEs associated with TWDM/TDM PON management. + +### **9.16.1 TWDM/TDM System Profile managed entity** + +This ME models the TWDM subsystem of NG-PON2 system and TWDM/TDM subsystem of ITU-T G.9804.2 based PON system. An instance of this ME corresponds to a physical or virtual slot of the ONU housing one or more access network interfaces. The instances of this ME are instantiated autonomously by the ONU. + +#### *Relationships* + +An instance of this ME is associated with an instance of a circuit pack that supports a PON interface function. It is, therefore, implicitly associated with all ANI-G MEs whose ME ID refers the specific Slot ID. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number is represented as 0xSS00, where SS indicates the slot ID (as defined in clause 9.1.5 and referenced in clause 9.2.1 of G.988. (R) (mandatory) (2 bytes) + +**Total TWDM channel number:** This attribute indicates the number of distinct TWDM channels the optical network termination (ONT) supports in given slot. (R) (mandatory) (1 byte) + +- Channel partition index:** Channel partition index represented as 0x0P, and maintained as a part of the OMCI MIB, rather than a TC layer config parameter. See clauses 6.1.5.9 of [ITU-T G.989.3] and 6.5.2.8 of [ITU-T G.9804.2] for a complete description. (R, W) (mandatory) (1 byte) +- Channel partition waiver timer:** An unsigned integer representing the time interval measured in seconds for which the ONU is blocked from an activation attempt on Channel Partition restriction. The timer corresponds to the $T_{cpi}$ parameter of G.989.3A1/G.9804.2 and measures the elapsed time from the moment an ONU finds a downstream wavelength channel belonging to a non-matching channel partition, to the moment the ONU resets its CPI in non-volatile memory to the default value (zero) in order to waive the CPI restriction. The default is 300 s. The value of 0xFFFF indicates infinity (no channel partition waiver is granted). (R, W) (mandatory) (4 bytes) +- LODS re-initialization timer:** This attribute, which corresponds to timer TO2 of [ITU-T G.989.3]/[ITU-T G.9804.2] expressed as an integer number of PHY frame intervals, specifies the duration of time an ONU without configured wavelength channel protection (WLCP = OFF) waits in the intermittent LODS (O6) state before transitioning into the initial (O1) state for reactivation. The default value upon instantiation is 1000 (125 ms). (R, W) (mandatory) (4 bytes) +- LODS protection timer:** This attribute, which corresponds to timer TO3 of [ITU-T G.989.3]/[ITU-T G.9804.2] expressed as an integer number of PHY frame intervals, specifies the duration of time an ONU with configured WLCP = ON waits in the intermittent LODS (O6) state before transitioning into the downstream tuning (O8) state to tune into the pre-configured protection wavelength channel. The default value upon instantiation is 200 (25 ms) for TWDM system. This attribute is not applicable to ITU-T G.9804.2 TDM systems (and will be ignored). (R, W) (mandatory) (4 bytes) +- Downstream tuning timer:** This attribute, which corresponds to timer TO4 of [ITU-T G.989.3]/[ITU-T G.9804.2] expressed as an integer number of PHY frame intervals, specifies the duration of time an ONU in the downstream tuning (O8) state attempts to validate the specified target downstream wavelength channel [obtaining downstream wavelength channel (DWLCH) ok to work], before transitioning into the initial (O1) state for reactivation. Note that the Rx tuning time proper is included in this interval. The default value upon instantiation is 1000 (125 ms). (R, W) (mandatory) (4 bytes) +- Upstream tuning timer:** This attribute, which corresponds to timer TO5 of [ITU-T G.989.3]/[ITU-T G.9804.2] expressed as an integer number of PHY frame intervals, specifies the duration of time an ONU in the upstream tuning (O9) state attempts to obtain the upstream tuning confirmation in the specified target upstream wavelength channel before transitioning into the initial (O1) state for reactivation. The default value upon instantiation is 1000 (125 ms). (R, W) (mandatory) (4 bytes) +- Location label 1:** This attribute represents the first part of the field, which is written by the OLT to provide the topological location information for the specific OLT channel termination within the operator domain. This attribute is not interpreted by the ONU, but may be used by a dual-managed ONU as a part of an alarm report provided over non-OMCI management channel. (R, W) (mandatory) (24 bytes) + +**Location label 2:** This attribute represents the second part of the field, which is written by the OLT to provide the topological location information for the specific OLT channel termination within the operator domain. This attribute is not interpreted by the ONU, but may be used by a dual-managed ONU as a part of an alarm report provided over non-OMCI management channel. (R, W) (mandatory) (24 bytes) + +#### *Actions* + +Get, set. + +### **9.16.2 TWDM/TDM channel managed entity** + +This ME provides an anchor for the MEs involved in collection of PM statistics per TWDM/TDM channel, as stipulated by clause 14 of [ITU-T G.989.3]. Instances of this ME are instantiated autonomously by the ONU. + +#### *Relationships* + +One or more instances of this ME are implicitly associated with the TWDM System profile ME. The number of instances created is announced by the total TWDM channel number attribute of the TWDM system profile ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. This 2 byte number is represented as 0xSSBB, where SS indicates the ONU slot ID, and BB is the TWDM channel ME number assigned by the ONU itself, starting from 0 in the ascending order. (R) (mandatory) (2 bytes) + +**Active channel indication:** The default value is false. The ONU sets the attribute to true when it receives the non-void Channel\_Profile PLOAM messages for that channel. The ONU clears the attribute when it receives the Channel\_Profile PLOAM message marked "void" for that channel. (R) (mandatory) (1 byte) + +**Operational channel indication:** A Boolean attribute that is set to true for an active TWDM channel in which the ONT is currently operating. The operational statistic is accumulated in the PM history data MEs associated with that TWDM channel. (R) (mandatory) (1 byte) + +**Downstream wavelength channel:** For an active TWDM channel, this attribute identifies the downstream wavelength channel in reference to Table 11-2 of [ITU-T G.989.2]. For fixed wavelength TDM system, the downstream wavelength channel number is 0x0F. For an inactive channel it has value 0xFF. (R) (mandatory) (1 byte) + +**Upstream wavelength channel:** For an active TWDM channel, this attribute identifies the upstream wavelength channel in reference to Table VIII-5 of [ITU-T G.989.2]. For fixed wavelength TDM system, the downstream wavelength channel number is 0x0F. For an inactive channel its value of 0xFF. (R) (mandatory) (1 byte) + +#### *Actions* + +Get, set. + +### 9.16.3 TWDM channel PHY/LODS performance monitoring history data + +This ME collects certain PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, and a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Total received words protected by bit-interleaved parity-32 (BIP-32):** The count of 4 byte words included in BIP-32 check. This is a product of the number of downstream FS frames received by the size of the downstream FS frame after the FEC parity byte, if any, have been removed. The count applies to the entire downstream data flow, whether or not addressed to that ONT. (R) (mandatory) (8 bytes) + +**BIP-32 bit error count:** Count of the bit errors in the received downstream FS frames as measured using BIP-32. If FEC is supported in the downstream direction, the BIP-32 count applies to the downstream FS frame after the FEC correction has been applied and the FEC parity bytes have been removed. (R) (mandatory) (4 bytes) + +**Corrected PSBd HEC error count:** The count of the errors in either CFC or OCS fields of the PSBd block that have been corrected using the HEC technique. (R) (mandatory) (4 bytes) + +**Uncorrectable PSBd HEC error count:** The count of the errors in either CFC or OCS fields of the PSBd block that could not be corrected using the HEC technique. (R) (mandatory) (4 bytes) + +**Corrected downstream FS header HEC error count:** The count of the errors in the downstream FS header that have been corrected using the HEC technique. (R) (mandatory) (4 bytes) + +**Uncorrectable downstream FS header HEC error count:** The count of the errors in the downstream FS header that could not be corrected using the HEC technique. (R) (mandatory) (4 bytes) + +**Total number of LODS events:** The count of the state transitions from O5.1/O5.2 to O6, referring to the ONU activation cycle state machine, clause 12 of [ITU-T G.989.3]. (R) (mandatory) (4 bytes) + +**LODS events restored in operating TWDM channel:** The count of LODS events cleared automatically without retuning. (R) (mandatory) (4 bytes) + +**LODS events restored in protection TWDM channel:** The count of LODS events resolved by retuning to a pre-configured protection TWDM channel. The event is counted against the original operating channel. (R) (mandatory) (4 bytes) + +**LODS events restored in discretionary TWDM channel:** The count of LODS events resolved by retuning to a TWDM channel chosen by the ONU, without retuning. Implies that the wavelength channel protection for the operating channel is not active. The event is counted against the original operating channel (R) (mandatory) (4 bytes) + +**LODS events resulting in reactivation:** The count of LODS events resolved through ONU reactivation; that is, either TO2 (without WLCP) or TO3 + TO4 (with WLCP) expires before the downstream channel is reacquired, referring to the ONU activation cycle state machine, clause 12 of [ITU-T G.989.3]. The event is counted against the original operating channel (R) (mandatory) (4 bytes) + +**LODS events resulting in reactivation after retuning to protection TWDM channel:** The count of LODS events resolved through ONU reactivation after attempted protection switching, which turns unsuccessful due to a handshake failure. (R) (mandatory) (4 bytes) + +**LODS events resulting in reactivation after retuning to discretionary TWDM channel:** The count of LODS events resolved through ONU reactivation after attempted retuning to a discretionary channel, which turns unsuccessful due to a handshake failure. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|---------------------------------------------------|--------------------------------------| +| 0 | N/A | | +| 1 | BIP-32 bit error count | 2 | +| 2 | PSBd HEC errors – corrected | 3 | +| 3 | PSBd HEC errors – uncorrectable | 4 | +| 4 | FS header errors – corrected | 5 | +| 5 | FS header errors – uncorrectable | 6 | +| 6 | Total LODS event count | 7 | +| 7 | LODS – restored in operating TWDM channel | 8 | +| 8 | LODS – restored in protection TWDM channel | 9 | +| 9 | LODS – restored in discretionary TWDM channel | 10 | +| 10 | LODS – reactivations | 11 | +| 11 | LODS – handshake failure in protection channel | 12 | +| 12 | LODS – handshake failure in discretionary channel | 13 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.16.4 TWDM channel XGEM performance monitoring history data + +This ME collects certain XGEM-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 64 bit ID:** This attribute points to an instance of the threshold data 64 bit ME that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Total transmitted XGEM frames:** The counter aggregated across all XGEM ports of the given ONU. (R) (mandatory) (8 byte) + +**Transmitted XGEM frames with LF bit not set:** The counter aggregated across all XGEM ports of the given ONU identifies the number of fragmentation operations. (R) (mandatory) (8 byte) + +**Total received XGEM frames:** The counter aggregated across all XGEM ports of the given ONU. (R) (mandatory) (8 byte) + +**Received XGEM frames with XGEM header HEC errors:** The counter aggregated across all XGEM ports of the given ONU identifies the number of loss XGEM frame delineation events. (R) (mandatory) (8 byte) + +**FS words lost to XGEM header HEC errors:** The counter of the FS frame words lost due to XGEM frame header errors that cause loss of XGEM frame delineation. (R) (mandatory) (8 byte) + +**XGEM encryption key errors:** The counter aggregated across all XGEM ports of the given ONU identifies the number of received XGEM frames that have to be discarded because of unknown or invalid encryption key. The number is included into the Total received XGEM frame count above. (R) (mandatory) (8 byte) + +**Total transmitted bytes in non-idle XGEM frames:** The counter aggregated across all XGEM ports of the given. (R) (mandatory) (8 byte) + +**Total received bytes in non-idle XGEM frames:** The counter aggregated across all XGEM ports of the given ONU. (R) (mandatory) (8 byte) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------|-----------------------------------------|-----------------------------------------| +| 0 | Received XGEM header HEC errors | 1 | +| 1 | FS words lost to XGEM header HEC errors | 2 | +| 2 | XGEM encryption key errors | 3 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 64 bit managed entity. + +### 9.16.5 TWDM channel PLOAM performance monitoring history data part 1 + +This ME collects certain PLOAM-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +The downstream PLOAM message counts of this ME include only the received PLOAM messages pertaining to the given ONU, i.e.: + +- unicast PLOAM messages, addressed by ONU-ID; +- broadcast PLOAM messages, addressed by serial number; +- broadcast PLOAM messages, addressed to all ONUs on the PON. + +This ME includes all PLOAM PM counters characterized as *mandatory* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**PLOAM MIC errors:** The counter of received PLOAM messages that remain unparsable due to MIC error. (R) (mandatory) (4 bytes) + +**Downstream PLOAM message count:** The counter of received broadcast and unicast PLOAM messages pertaining to the given ONU. (R) (mandatory) (4 bytes) + +**Ranging\_Time message count:** The counter of received Ranging\_Time PLOAM messages. (R) (mandatory) (4 bytes) + +**Protection\_Control message count:** The counter of received Protection\_Control PLOAM messages. (R) (mandatory) (4 bytes) + +**Adjust\_Tx\_Wavelength message count:** The counter of received Adjust\_Tx\_Wavelength PLOAM messages. (R) (mandatory) (4 bytes) + +**Adjust\_Tx\_Wavelength adjustment amplitude:** An estimator of the absolute value of the transmission wavelength adjustment. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | PLOAM MIC errors | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### **9.16.6 TWDM channel PLOAM performance monitoring history data part 2** + +This ME collects additional PLOAM-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +The downstream PLOAM message counts of this ME include only the received PLOAM messages pertaining to the given ONU, i.e.: + +- unicast PLOAM messages, addressed by ONU-ID; +- broadcast PLOAM messages, addressed by serial number; +- broadcast PLOAM messages, addressed to all ONUs on the PON. + +All these counters are characterized as *optional* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**System\_Profile message count:** The counter of received System\_Profile PLOAM messages. (R) (mandatory) (4 bytes) + +**Channel\_Profile message count:** The counter of received Channel\_Profile PLOAM messages. (R) (mandatory) (4 bytes) + +**Burst\_Profile message count:** The counter of received Burst\_Profile PLOAM messages. (R) (mandatory) (4 bytes) + +**Assign\_ONU-ID message count:** The counter of received Assign\_ONU-ID PLOAM messages. (R) (mandatory) (4 bytes) + +- Unsatisfied Adjust\_Tx\_Wavelength requests:** The counter of Adjust\_Tx\_Wavelength requests not applied or partially applied due to target US wavelength being out of Tx tuning range. (R) (mandatory) (4 bytes) +- Deactivate\_ONU-ID message count:** The counter of received Deactivate\_ONU-ID PLOAM messages. (R) (mandatory) (4 bytes) +- Disable\_Serial\_Number message count:** The counter of received Disable\_Serial\_Number PLOAM messages. (R) (mandatory) (4 bytes) +- Request\_Registration message count:** The counter of received Request\_Registration PLOAM messages. (R) (mandatory) (4 bytes) +- Assign\_Alloc-ID message count:** The counter of received Assign\_Alloc-ID PLOAM messages. (R) (mandatory) (4 bytes) +- Key\_Control message count:** The counter of received Key\_Control PLOAM messages. (R) (mandatory) (4 bytes) +- Sleep\_Allow message count:** The counter of received Sleep\_Allow PLOAM messages. (R) (mandatory) (4 bytes) +- Tuning\_Control/Request message count:** The counter of received Tuning\_Control PLOAM messages with Request operation code. (R) (mandatory) (4 bytes) +- Tuning\_Control/Complete\_d message count:** The counter of received Tuning\_Control PLOAM messages with Complete\_d operation code. (R) (mandatory) (4 bytes) +- Calibration\_Request message count:** The counter of received Calibration\_Request PLOAM messages. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-------------------------------------------|--------------------------------------| +| 0 | Unsatisfied Adjust_Tx_Wavelength requests | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### **9.16.7 TWDM channel PLOAM performance monitoring history data part 3** + +This ME collects remaining PLOAM-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +This ME contains the counters related to transmitted upstream PLOAM messages. All these counters are characterized as *optional* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### *Relationships* + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### *Attributes* + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Upstream PLOAM message count:** The aggregate counter of PLOAM messages, other than AK PLOAM MT, transmitted by the given ONU. (R) (mandatory) (4 bytes) + +**Serial\_Number\_ONU (in-band) message count:** The counter of transmitted in-band Serial\_Number\_ONU PLOAM messages. (R) (mandatory) (4 bytes) + +**Serial\_Number\_ONU (AMCC) message count:** The counter of transmitted auxiliary management and control channel (AMCC) Serial\_Number\_ONU PLOAM messages. (R) (mandatory) (4 bytes) + +**Registration message count:** The counter of transmitted Registration PLOAM messages. (R) (mandatory) (4 bytes) + +**Key\_Report message count:** The counter of transmitted Key\_Report PLOAM messages. (R) (mandatory) (4 bytes) + +**Acknowledgement message count:** The counter of transmitted Registration PLOAM messages. (R) (mandatory) (4 bytes) + +**Sleep\_Request message count:** The counter of transmitted Sleep\_Request PLOAM messages. (R) (mandatory) (4 bytes) + +**Tuning\_Response (ACK/NACK) message count:** The counter of transmitted Tuning\_Response PLOAM messages with ACK/NACK operation code. (R) (mandatory) (4 bytes) + +**Tuning\_Response (Complete\_u/Rollback) message count:** The counter of transmitted Tuning\_Response PLOAM messages with Complete\_u/Rollback operation code. (R) (mandatory) (4 bytes) + +**Power\_Consumption\_Report message count:** The counter of transmitted Power\_Consumption\_Report PLOAM messages. (R) (mandatory) (4 bytes) + +**Change\_Power\_Level parameter error count:** The counter of transmitted Acknowledgement PLOAM messages with Parameter Error completion code in response to Change\_Power\_Level PLOAM message. (R) (mandatory) (4 bytes) + +#### *Actions* + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|------------------------------------------|--------------------------------------| +| 0 | Change_Power_Level parameter error count | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.16.8 TWDM channel tuning performance monitoring history data part 1 + +This ME collects certain tuning-control-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +The relevant events this ME is concerned with are counted towards the PM statistics associated with the source TWDM channel. The attribute descriptions refer to the ONU activation cycle states and timers specified in clause 12 of [ITU-T G.989.3]. This ME contains the counters characterized as *mandatory* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Tuning control requests for Rx only or Rx and Tx:** The counter of received Tuning\_Control PLOAM messages with Request operation code that contain tuning instructions either for receiver only or for both receiver and transmitter. (R) (mandatory) (4 bytes) + +**Tuning control requests for Tx only:** The counter of received Tuning\_Control PLOAM messages with Request operation code that contain tuning instructions for transmitter only. (R) (mandatory) (4 bytes) + +**Tuning control requests rejected/INT\_SFC:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and INT\_SFC response code, indicating inability to start transceiver tuning by the specified time (SFC). (R) (mandatory) (4 bytes) + +**Tuning control requests rejected/DS\_xxx:** The aggregate counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and any DS\_xxx response code, indicating target downstream wavelength channel inconsistency. (R) (mandatory) (4 bytes) + +- Tuning control requests rejected/US\_xxx:** The aggregate counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and any US\_xxx response code, indicating target upstream wavelength channel inconsistency. (R) (mandatory) (4 bytes) +- Tuning control requests fulfilled with ONU reacquired at target channel:** The counter of controlled tuning attempts for which an upstream tuning confirmation has been obtained in the target channel. (R) (mandatory) (4 bytes) +- Tuning control requests failed due to target DS wavelength channel not found:** The counter of controlled tuning attempts that failed due to timer TO4 expiration in the DS Tuning state (O8) in the target channel. (R) (mandatory) (4 bytes) +- Tuning control requests failed due to no feedback in target DS wavelength channel:** The counter of controlled tuning attempts that failed due to timer TO5 expiration in the US Tuning state (O9) in the target channel. (R) (mandatory) (4 bytes) +- Tuning control requests resolved with ONU reacquired at discretionary channel:** The counter of controlled tuning attempts for which an upstream tuning confirmation has been obtained in the discretionary channel. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/COM\_DS:** The counter of controlled tuning attempts that failed due to communication condition in the target channel, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and COM\_DS response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/DS\_xxx:** The aggregate counter of controlled tuning attempts that failed due to target downstream wavelength channel inconsistency, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and any DS\_xxx response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_xxx:** The aggregate counter of controlled tuning attempts that failed due to target upstream wavelength channel parameter violation, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_xxx response code. (R) (mandatory) (4 bytes) +- Tuning control requests failed with ONU reactivation:** The counter of controlled tuning attempts that failed on any reason, with expiration of timers TO4 or TO5 causing the ONU transition into state O1. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|------------------------------------------|--------------------------------------| +| 0 | Tuning control requests rejected/INT_SFC | 1 | +| 1 | Tuning control requests rejected/DS_xxx | 2 | +| 2 | Tuning control requests rejected/US_xxx | 3 | +| 3 | Tuning control requests failed/TO4 exp. | 4 | + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|---------------------------------------------|--------------------------------------| +| 4 | Tuning control requests failed/TO5 exp. | 5 | +| 5 | Tuning control requests Rollback/COM_DS | 6 | +| 6 | Tuning control requests Rollback/DS_xxx | 7 | +| 7 | Tuning control requests Rollback/US_xxx | 8 | +| 8 | Tuning control requests failed/Reactivation | 9 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.16.9 TWDM channel tuning performance monitoring history data part 2 + +This ME collects additional tuning-control-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +The relevant events this ME is concerned with are counted towards the PM statistics associated with the source TWDM channel. This ME contains the counters characterized as *optional* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Tuning control requests rejected/DS\_ALBL:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and DS\_ALBL response code, indicating downstream administrative label inconsistency. (R) (mandatory) (4 bytes) + +**Tuning control requests rejected/DS\_VOID:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and DS\_VOID response code, indicating that the target downstream wavelength channel descriptor is void. (R) (mandatory) (4 bytes) + +**Tuning control requests rejected/DS\_PART:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and DS\_PART response code, indicating that tuning request involves channel partition violation. (R) (mandatory) (4 bytes) + +- Tuning control requests rejected/DS\_TUNR:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and DS\_TUNR response code, indicating that the target DS wavelength channel is out of receiver tuning range. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/DS\_LNRT:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and DS\_LNRT response code, indicating downstream line rate inconsistency in the target channel. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/DS\_LNCD:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and DS\_LNCD response code, indicating downstream line code inconsistency in the target channel. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_ALBL:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_ALBL response code, indicating upstream administrative label inconsistency. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_VOID:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_VOID response code, indicating that the target upstream wavelength channel descriptor is void. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_TUNR:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_TUNR response code, indicating that the target US wavelength channel is out of transmitter tuning range. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_CLBR:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_CLBR response code, indicating that the transmitter has insufficient calibration accuracy in the target US wavelength channel. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_LKTP:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_LKTP response code, indicating upstream optical link type inconsistency. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_LNRT:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_LNRT response code, indicating upstream line rate inconsistency in the target channel. (R) (mandatory) (4 bytes) +- Tuning control requests rejected/US\_LNCD:** The counter of transmitted Tuning\_Response PLOAM messages with NACK operation code and US\_LNCD response code, indicating upstream line code inconsistency in the target channel. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No.
(Note) | +|--------------|------------------------------------------|-----------------------------------------| +| 0 | Tuning control requests rejected/DS_ALBL | 1 | +| 1 | Tuning control requests rejected/DS_VOID | 2 | +| 2 | Tuning control requests rejected/DS_PART | 3 | +| 3 | Tuning control requests rejected/DS_TUNR | 4 | +| 4 | Tuning control requests rejected/DS_LNRT | 5 | +| 5 | Tuning control requests rejected/DS_LNCD | 6 | +| 6 | Tuning control requests rejected/US_ALBL | 7 | +| 7 | Tuning control requests rejected/US_VOID | 8 | +| 8 | Tuning control requests rejected/US_TUNR | 9 | +| 9 | Tuning control requests rejected/US_CLBR | 10 | +| 10 | Tuning control requests rejected/US_LKTP | 11 | +| 11 | Tuning control requests rejected/US_LNRT | 12 | +| 12 | Tuning control requests rejected/US_LNCD | 13 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.16.10 TWDM channel tuning performance monitoring history data part 3 + +This ME collects remaining tuning-control-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +The relevant events this ME is concerned with are counted towards the PM statistics associated with the source TWDM channel. This ME contains the counters characterized as *optional* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**Tuning control requests Rollback/DS\_ALBL:** The counter of controlled tuning attempts that failed due to downstream administrative label inconsistency, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and DS\_ALBL response code. (R) (mandatory) (4 bytes) + +- Tuning control requests Rollback/DS\_LKTP:** The counter of controlled tuning attempts that failed due to downstream optical link type inconsistency, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and DS\_LKTP response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_ALBL:** The counter of controlled tuning attempts that failed due to upstream administrative label violation, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_ALBL response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_VOID:** The counter of controlled tuning attempts that failed due to the target upstream wavelength channel descriptor being void, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_VOID response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_TUNR:** The counter of controlled tuning attempts that failed due to the transmitter tuning range violation, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_TUNR response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_LKTP:** The counter of controlled tuning attempts that failed due to the upstream optical link type violation, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_LKTP response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_LNRT:** The counter of controlled tuning attempts that failed due to the upstream line rate violation, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_LNRT response code. (R) (mandatory) (4 bytes) +- Tuning control requests Rollback/US\_LNCD:** The counter of controlled tuning attempts that failed due to the upstream line code violation, as indicated by the Tuning\_Response PLOAM message with Rollback operation code and US\_LNCD response code. (R) (mandatory) (4 bytes) + +#### *Actions* + +- Create, delete, get, set +- Get current data (optional) + +#### *Notifications* + +#### **Threshold crossing alert** + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|-------------------------------------------|--------------------------------------| +| 0 | Tuning control requests Rollback/DS_ALBL | 1 | +| 1 | Tuning control requests Rollback /DS_LKTP | 2 | +| 2 | Tuning control requests Rollback/US_ALBL | 3 | +| 3 | Tuning control requests Rollback /US_VOID | 4 | +| 4 | Tuning control requests Rollback/US_TUNR | 5 | +| 5 | Tuning control requests Rollback /US_LKTP | 6 | +| 6 | Tuning control requests Rollback/US_LNRT | 7 | +| 7 | Tuning control requests Rollback /US_LNCD | 8 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +### 9.16.11 TWDM channel OMCI performance monitoring history data + +This ME collects OMCI-related PM data associated with the slot/circuit pack, hosting one or more ANI-G MEs, for a specific TWDM channel. Instances of this ME are created and deleted by the OLT. + +The counters maintained by this ME are characterized as *optional* in clause 14 of [ITU-T G.989.3]. + +For a complete discussion of generic PM architecture, refer to clause I.4. + +#### Relationships + +An instance of this ME is associated with an instance of TWDM channel ME. + +#### Attributes + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of the TWDM channel ME. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +**OMCI baseline message count:** The counter of baseline format OMCI messages directed to the given ONU. (R) (mandatory) (4 bytes) + +**OMCI extended message count:** The counter of extended format OMCI messages directed to the given ONU. (R) (mandatory) (4 bytes) + +**OMCI MIC error count:** The counter of OMCI messages received with MIC errors. (R) (mandatory) (4 bytes) + +#### Actions + +Create, delete, get, set + +Get current data (optional) + +#### Notifications + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold value attribute No. (Note) | +|--------------|--------------------------|--------------------------------------| +| 0 | OMCI MIC error count | 1 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1/2 managed entities. + +# 10 This clause is intentionally left blank + +# 11 ONU management and control protocol + +## 11.1 Baseline and extended messages + +This clause defines two formats for OMCI messages, baseline and extended. + +ITU-T GTC based PON systems are free to use either the baseline or the extended OMCI message format. The baseline format is the default at initialization. Use of the extended format is then negotiated between the OLT and ONU. + +The conventions for the use of baseline and extended messages by systems complying with other Recommendations are for further study. + +Baseline messages have 48 byte fixed length PDUs, while extended messages have variable length PDUs. A receiver that does not support extended messages may therefore reject an extended message based on nothing more than their length. + +Both baseline and extended messages carry an MIC in their final 4 bytes. This facilitates *ad hoc* recovery of both MTs by a receiver. In ITU-T G.984 systems, the MIC is an ITU-T I.363.5 CRC; in the subsequent ITU-T PON systems, the MIC is a cryptographic hash as specified in the respective TC layer specification. + +Baseline and extended messages are distinguished from one another by the device identifier field, which is in the same byte location in both MTs. Baseline messages contain device identifier 0x0A, while extended messages employ device identifier 0x0B. + +All G-PON ONUs and OLTs are required to support the baseline format. During initialization, and whenever the ONU is re-ranged on to the PON, both entities use the baseline format to establish communications and to negotiate their capabilities. If both endpoints support extended messages, they may or may not choose to conduct all or some subsequent communications in the extended message set. Baseline messages may be used for any transaction, i.e., any exchange of one or more related messages such as a get/get-next sequence. + +Figure 11.1-1 illustrates the negotiation and the exchange of messages in one or the other message format. + +![Sequence diagram of G-PON OMCI message set negotiation between OLT and ONU. The diagram shows the OLT sending an Alarm_A message, then a Get_A (ONU2-G, OMCC version) message. The ONU responds with Get response_A, indicating support for the extended message set. The OLT then sends an OMCI message_B, which the ONU responds to with OMCI response_B. Finally, the OLT sends an Alarm_B message, and the ONU responds with OMCI message_A and OMCI response_A. Callouts explain the rules for message set usage during negotiation.](2b10056b07ec6fecdc2d1b4c2000a2f6_img.jpg) + +OLT + +ONU + +AlarmA (ME, parameters) + +Subscript A designates a baseline message set. B designates an extended message set. +The OLT queries ONU capabilities before it is allowed to use extended messages. + +The ONU must use message set A in autonomous notifications unless it has received a message set B command from the OLT during current session. + +GetA (ONU2-G, OMCC version) + +Get responseA (ONU2-G, OMCC version supports the extended message set) + +If an extended message set is not supported by the ONU, the OLT may not use the extended message set. +If the extended message set is supported by the ONU, the OLT may use either message set at will. + +OMCI messageB (... parameters ...) + +OMCI responseB (... parameters ...) + +The ONU uses message set B in response to message set B command. + +The ONU is allowed to use message set B in autonomous notifications only if it has received a message set B command from the OLT during current session. + +AlarmB (ME, parameters) + +OMCI messageA (... parameters ...) + +OMCI responseA (... parameters ...) + +Even though an extended message set has been negotiated, the OLT may use a baseline message set. The ONU responds with baseline messages. + +G.988(12)\_F11.1-1 + +Sequence diagram of G-PON OMCI message set negotiation between OLT and ONU. The diagram shows the OLT sending an Alarm\_A message, then a Get\_A (ONU2-G, OMCC version) message. The ONU responds with Get response\_A, indicating support for the extended message set. The OLT then sends an OMCI message\_B, which the ONU responds to with OMCI response\_B. Finally, the OLT sends an Alarm\_B message, and the ONU responds with OMCI message\_A and OMCI response\_A. Callouts explain the rules for message set usage during negotiation. + +**Figure 11.1-1 – G-PON OMCI message set negotiation** + +If a G-PON OLT has *a priori* knowledge that the ONU supports the extended message set, it may choose to omit the query step. However, a G-PON ONU may not transmit extended messages, including autonomous notifications, until it has received at least one extended message from the OLT during the current session (since initialization or re-activation on the PON). + +## 11.2 Common message characteristics + +Each OMCI protocol packet is encapsulated directly in one GEM frame, or several GEM frames if necessary to satisfy the normal fragmentation rules. The GEM frame header contains the OMCC port-ID. + +Table 11.2-1 shows the baseline message format. The packet has a fixed length of 48 bytes. + +**Table 11.2-1 – Baseline OMCI message format** + +| Byte number | Size | Use | +|-------------|------|------------------------------------| +| 1..2 | 2 | Transaction correlation identifier | +| 3 | 1 | Message type | +| 4 | 1 | Device identifier | +| 5..8 | 4 | Managed entity identifier | +| 9..40 | 32 | Message contents | +| 41..48 | 8 | OMCI trailer | + +Table 11.2-2 shows the extended message format. The packet has variable length $N$ , up to 1980 bytes. + +**Table 11.2-2 – Extended OMCI message format** + +| Byte number | Size | Use | +|-------------|------|------------------------------------| +| 1..2 | 2 | Transaction correlation identifier | +| 3 | 1 | Message type | +| 4 | 1 | Device identifier | +| 5..8 | 4 | Managed entity identifier | +| 9..10 | 2 | Message contents length | +| 11..(N-4) | – | Message contents | +| (N-3)..N | 4 | Message integrity check (MIC) | + +Clauses 11.2.1 to 11.2.8 specify each field of these messages. + +### 11.2.1 Transaction correlation identifier + +The transaction correlation identifier is used to associate a request message with its response message. For request messages, the OLT selects a transaction identifier, an arbitrary value that should be chosen to avoid the possibility of ambiguous responses from ONUs. A response message carries the transaction identifier of the message to which it is responding. The transaction identifier of messages generated autonomously by an ONU is 0. + +As explained in clause B.2.2, and for the baseline message format only, the MSB of the transaction correlation identifier indicates the priority of the message. The following coding is used: 0 = low priority, 1 = high priority. The OLT decides whether a command should be executed with low or high priority. The extended message format does not recognize priorities. + +### 11.2.2 Message type + +The MT field is subdivided into four parts. These are shown in Figure 11.2.2-1. + +![](074b3d6a58da85d72b21ac0217dbdc9f_img.jpg) + +| | | | | | | +|-----|---|----|----|----|---| +| Bit | 8 | 7 | 6 | 5 | 1 | +| | 0 | AR | AK | MT | | + +**Figure 11.2.2-1 – Message type field subdivision** + +Bit 8, the MSB, is reserved for future use, and is always 0. + +Bit 7, acknowledge request (AR), indicates whether the message requires an AK. An AK is a response to an action request, not a link layer handshake. If an AK is expected, this bit is set to 1. If no AK is expected, this bit is 0. In messages sent by the ONU, this bit is always 0. + +Bit 6, AK, indicates whether this message is an AK to an action request. If a message is an AK, this bit is set to 1. If the message is not a response to a command, this bit is set to 0. In messages sent by the OLT, this bit is always 0. + +Bits 5..1, MT, indicate the MT, as defined in Table 11.2.2-1. Values not shown in Table 11.2.2-1 are reserved. + +**Table 11.2.2-1 – OMCI message types** + +| MT | Type | Purpose | AK | Increment MIB data sync | +|----|-------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|-------------------------| +| 4 | Create | Create a managed entity instance with its attributes | Yes | Yes | +| 6 | Delete | Delete a managed entity instance | Yes | Yes | +| 8 | Set | Set one or more attributes of a managed entity | Yes | (Note 1) | +| 9 | Get | Get one or more attributes of a managed entity. When directed to a table attribute, get causes the ONU to latch a copy of the table for retrieval with a sequence of get next commands. | Yes | No | +| 11 | Get all alarms | Latch the alarm statuses of all managed entities and reset the alarm message counter | Yes | No | +| 12 | Get all alarms next | Get the active alarm status of the next managed entity or entities from the latched alarm status copy | Yes | No | +| 13 | MIB upload | Latch a copy of the MIB. Some MEs and some attributes are not included in an MIB upload. | Yes | No | +| 14 | MIB upload next | Get the next set of attributes of the managed entity instances included in the latched MIB copy | Yes | No | +| 15 | MIB reset | Clear the MIB, re-initialize it to its default, and reset the MIB data sync counter to 0 | Yes | No | +| 16 | Alarm | Notification of an alarm or a threshold crossing alert | No | No | +| 17 | Attribute value change | Autonomous notification of an attribute value change | No | No | +| 18 | Test | Request a test on a specific managed entity | Yes | No | +| 19 | Start software download | Start a software download action | Yes | Yes | +| 20 | Download section | Download a section of a software image | (Note 2) | No | +| 21 | End software download | End of a software download action | Yes | Yes | +| 22 | Activate software | Activate the downloaded software image | Yes | Yes | +| 23 | Commit software | Commit the downloaded software image | Yes | Yes | +| 24 | Synchronize time | Synchronize PM interval time between OLT and ONU | Yes | No | +| 25 | Reboot | Reboot ONU or circuit pack | Yes | No | + +**Table 11.2.2-1 – OMCI message types** + +| MT | Type | Purpose | AK | Increment MIB data sync | +|----|--------------------|-------------------------------------------------------------------------------------------------------------|-----|-------------------------| +| 26 | Get next | Get the latched attribute values of the managed entity within the current snapshot | Yes | No | +| 27 | Test result | Notification of result initiated by a test command | No | No | +| 28 | Get current data | Get current counter value associated with one or more attributes of a performance monitoring managed entity | Yes | No | +| 29 | Set table (Note 3) | Set one or more rows of a table | Yes | Yes | + +NOTE 1 – MIB sync is incremented if a set action successfully updates any of the attributes specified, even if some other attributes of the same set action were to fail. +NOTE 2 – The download section action is acknowledged only for the last section within a window. See clause I.3. +NOTE 3 – Set table is defined only in the extended message set. + +### 11.2.3 Device identifier + +In baseline OMCI messages, this field is defined to be 0x0A. + +In extended OMCI messages, this field is defined to be 0x0B. + +All other values are reserved. + +### 11.2.4 Managed entity identifier + +The ME identifier comprises 4 bytes. The most significant 2 bytes of the ME identifier field designate the ME class value of the target ME. The maximum number of possible ME classes is thus 65535 (0 is not used). The least significant 2 bytes of the ME identifier field identify the ME instance. Depending on the ME class, there may be none, one (e.g., ONU-G) or several (e.g., MAC bridge port config data) instances in an ONU. + +Table 11.2.4-1 specifies the MEs and their class values in the OMCI. + +NOTE – This table contains all ME classes ever standardized for the OMCI, including [ITU-T G.983.2] and [ITU-T G.984.4], as well as features now deprecated. These class values remain assigned to their original values. + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|----------------------------|------------------------| +| 1 | ONT B-PON | +| 2 | ONU data | +| 3 | PON IF line cardholder | +| 4 | PON IF line card | +| 5 | Cardholder | +| 6 | Circuit pack | +| 7 | Software image | +| 8 | UNI B-PON | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|----------------------------|--------------------------------------------------------------------| +| 9 | TC Adapter B-PON | +| 10 | Physical path termination point ATM UNI | +| 11 | Physical path termination point Ethernet UNI | +| 12 | Physical path termination point CES UNI | +| 13 | Logical $N \times 64$ kbit/s sub-port connection termination point | +| 14 | Interworking VCC termination point | +| 15 | AAL1 profile B-PON | +| 16 | AAL5 profile | +| 17 | AAL1 protocol monitoring history data B-PON | +| 18 | AAL5 performance monitoring history data | +| 19 | AAL2 profile | +| 20 | (Intentionally left blank) | +| 21 | CES service profile | +| 22 | (Reserved) | +| 23 | CES physical interface performance monitoring history data | +| 24 | Ethernet performance monitoring history data | +| 25 | VP network CTP B-PON | +| 26 | ATM VP cross-connection | +| 27 | Priority queue B-PON | +| 28 | DBR/CBR traffic descriptor | +| 29 | UBR traffic descriptor | +| 30 | SBR1/VBR1 traffic descriptor | +| 31 | SBR2/VBR2 traffic descriptor | +| 32 | SBR3/VBR3 traffic descriptor | +| 33 | ABR traffic descriptor | +| 34 | GFR traffic descriptor | +| 35 | ABT/DT/IT traffic descriptor | +| 36 | UPC disagreement monitoring history data B-PON | +| 37 | (Intentionally left blank) | +| 38 | ANI (B-PON) | +| 39 | PON TC adapter | +| 40 | PON physical path termination point | +| 41 | TC adapter protocol monitoring history data | +| 42 | Threshold data B-PON | +| 43 | Operator specific | +| 44 | Vendor specific | +| 45 | MAC bridge service profile | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|-------------------------------------------------------------| +| 46 | MAC bridge configuration data | +| 47 | MAC bridge port configuration data | +| 48 | MAC bridge port designation data | +| 49 | MAC bridge port filter table data | +| 50 | MAC bridge port bridge table data | +| 51 | MAC bridge performance monitoring history data | +| 52 | MAC bridge port performance monitoring history data | +| 53 | Physical path termination point POTS UNI | +| 54 | Voice CTP | +| 55 | Voice PM history data | +| 56 | AAL2 PVC profile B-PON | +| 57 | AAL2 CPS protocol monitoring history data B-PON | +| 58 | Voice service profile | +| 59 | LES service profile | +| 60 | AAL2 SSCS parameter profile1 | +| 61 | AAL2 SSCS parameter profile2 | +| 62 | VP performance monitoring history data | +| 63 | Traffic scheduler B-PON | +| 64 | T-CONT buffer | +| 65 | UBR+ traffic descriptor | +| 66 | AAL2 SSCS protocol monitoring history data B-PON | +| 67 | IP port configuration data | +| 68 | IP router service profile | +| 69 | IP router configuration data | +| 70 | IP router performance monitoring history data 1 | +| 71 | IP router performance monitoring history data 2 | +| 72 | ICMP performance monitoring history data 1 | +| 73 | ICMP performance monitoring history data 2 | +| 74 | IP route table | +| 75 | IP static routes | +| 76 | ARP service profile | +| 77 | ARP configuration data | +| 78 | VLAN tagging operation configuration data | +| 79 | MAC bridge port filter pre-assign table | +| 80 | Physical path termination point ISDN UNI | +| 81 | (Reserved) | +| 82 | Physical path termination point video UNI | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|----------------------------------------------------------------| +| 83 | Physical path termination point LCT UNI | +| 84 | VLAN tagging filter data | +| 85 | ONU B-PON | +| 86 | ATM VC cross-connection | +| 87 | VC network CTP B-PON | +| 88 | VC PM history data | +| 89 | Ethernet performance monitoring history data 2 | +| 90 | Physical path termination point video ANI | +| 91 | Physical path termination point IEEE 802.11 UNI | +| 92 | IEEE 802.11 station management data 1 | +| 93 | IEEE 802.11 station management data 2 | +| 94 | IEEE 802.11 general purpose object | +| 95 | IEEE 802.11 MAC and PHY operation and antenna data | +| 96 | IEEE 802.11 performance monitoring history data | +| 97 | IEEE 802.11 PHY FHSS DSSS IR tables | +| 98 | Physical path termination point xDSL UNI part 1 | +| 99 | Physical path termination point xDSL UNI part 2 | +| 100 | xDSL line inventory and status data part 1 | +| 101 | xDSL line inventory and status data part 2 | +| 102 | xDSL channel downstream status data | +| 103 | xDSL channel upstream status data | +| 104 | xDSL line configuration profile part 1 | +| 105 | xDSL line configuration profile part 2 | +| 106 | xDSL line configuration profile part 3 | +| 107 | xDSL channel configuration profile | +| 108 | xDSL subcarrier masking downstream profile | +| 109 | xDSL subcarrier masking upstream profile | +| 110 | xDSL PSD mask profile | +| 111 | xDSL downstream RFI bands profile | +| 112 | xDSL xTU-C performance monitoring history data part 1 | +| 113 | xDSL xTU-R performance monitoring history data | +| 114 | xDSL xTU-C channel performance monitoring history data | +| 115 | xDSL xTU-R channel performance monitoring history data | +| 116 | TC adaptor performance monitoring history data xDSL | +| 117 | Physical path termination point VDSL UNI (ITU-T G.993.1 VDSL1) | +| 118 | VDSL VTU-O physical data | +| 119 | VDSL VTU-R physical data | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|---------------------------------------------------------| +| 120 | VDSL channel data | +| 121 | VDSL line configuration profile | +| 122 | VDSL channel configuration profile | +| 123 | VDSL band plan configuration profile | +| 124 | VDSL VTU-O physical interface monitoring history data | +| 125 | VDSL VTU-R physical interface monitoring history data | +| 126 | VDSL VTU-O channel performance monitoring history data | +| 127 | VDSL VTU-R channel performance monitoring history data | +| 128 | Video return path service profile | +| 129 | Video return path performance monitoring history data | +| 130 | IEEE 802.1p mapper service profile | +| 131 | OLT-G | +| 132 | Multicast interworking VCC termination point | +| 133 | ONU power shedding | +| 134 | IP host config data | +| 135 | IP host performance monitoring history data | +| 136 | TCP/UDP config data | +| 137 | Network address | +| 138 | VoIP config data | +| 139 | VoIP voice CTP | +| 140 | Call control performance monitoring history data | +| 141 | VoIP line status | +| 142 | VoIP media profile | +| 143 | RTP profile data | +| 144 | RTP performance monitoring history data | +| 145 | Network dial plan table | +| 146 | VoIP application service profile | +| 147 | VoIP feature access codes | +| 148 | Authentication security method | +| 149 | SIP config portal | +| 150 | SIP agent config data | +| 151 | SIP agent performance monitoring history data | +| 152 | SIP call initiation performance monitoring history data | +| 153 | SIP user data | +| 154 | MGC config portal | +| 155 | MGC config data | +| 156 | MGC performance monitoring history data | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|------------------------------------------------------------------------| +| 157 | Large string | +| 158 | ONU remote debug | +| 159 | Equipment protection profile | +| 160 | Equipment extension package | +| 161 | Port-mapping package BPON (B-PON only; use 297 for G-PON) | +| 162 | Physical path termination point MoCA UNI | +| 163 | MoCA Ethernet performance monitoring history data | +| 164 | MoCA interface performance monitoring history data | +| 165 | VDSL2 line configuration extensions | +| 166 | xDSL line inventory and status data part 3 | +| 167 | xDSL line inventory and status data part 4 | +| 168 | VDSL2 line inventory and status data part 1 | +| 169 | VDSL2 line inventory and status data part 2 | +| 170 | VDSL2 line inventory and status data part 3 | +| 171 | Extended VLAN tagging operation configuration data | +| 172..239 | Reserved for future B-PON managed entities | +| 240-255 | Reserved for vendor-specific managed entities | +| 256 | ONU-G (NOTE – In [ITU-T G.984.4] this was called ONT-G) | +| 257 | ONU2-G (NOTE – In [ITU-T G.984.4] this was called ONT2-G) | +| 258 | ONU-G (deprecated – note that the name is re-used for code point 256) | +| 259 | ONU2-G (deprecated – note that the name is re-used for code point 257) | +| 260 | PON IF line card-G | +| 261 | PON TC adapter-G | +| 262 | T-CONT | +| 263 | ANI-G | +| 264 | UNI-G | +| 265 | ATM interworking VCC termination point | +| 266 | GEM interworking termination point | +| 267 | GEM port performance monitoring history data (obsolete) | +| 268 | GEM port network CTP | +| 269 | VP network CTP | +| 270 | VC network CTP-G | +| 271 | GAL TDM profile (deprecated) | +| 272 | GAL Ethernet profile | +| 273 | Threshold data 1 | +| 274 | Threshold data 2 | +| 275 | GAL TDM performance monitoring history data (deprecated) | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|--------------------------------------------------| +| 276 | GAL Ethernet performance monitoring history data | +| 277 | Priority queue | +| 278 | Traffic scheduler | +| 279 | Protection data | +| 280 | Traffic descriptor | +| 281 | Multicast GEM interworking termination point | +| 282 | Pseudowire termination point | +| 283 | RTP pseudowire parameters | +| 284 | Pseudowire maintenance profile | +| 285 | Pseudowire performance monitoring history data | +| 286 | Ethernet flow termination point | +| 287 | OMCI | +| 288 | Managed entity | +| 289 | Attribute | +| 290 | Dot1X port extension package | +| 291 | Dot1X configuration profile | +| 292 | Dot1X performance monitoring history data | +| 293 | Radius performance monitoring history data | +| 294 | TU CTP | +| 295 | TU performance monitoring history data | +| 296 | Ethernet performance monitoring history data 3 | +| 297 | Port-mapping package | +| 298 | Dot1 rate limiter | +| 299 | Dot1ag maintenance domain | +| 300 | Dot1ag maintenance association | +| 301 | Dot1ag default MD level | +| 302 | Dot1ag MEP | +| 303 | Dot1ag MEP status | +| 304 | Dot1ag MEP CCM database | +| 305 | Dot1ag CFM stack | +| 306 | Dot1ag chassis-management info | +| 307 | Octet string | +| 308 | General purpose buffer | +| 309 | Multicast operations profile | +| 310 | Multicast subscriber config info | +| 311 | Multicast subscriber monitor | +| 312 | FEC performance monitoring history data | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|------------------------------------------------------------------| +| 313 | RE ANI-G | +| 314 | Physical path termination point RE UNI | +| 315 | RE upstream amplifier | +| 316 | RE downstream amplifier | +| 317 | RE config portal | +| 318 | File transfer controller | +| 319 | CES physical interface performance monitoring history data 2 | +| 320 | CES physical interface performance monitoring history data 3 | +| 321 | Ethernet frame performance monitoring history data downstream | +| 322 | Ethernet frame performance monitoring history data upstream | +| 323 | VDSL2 line configuration extensions 2 | +| 324 | xDSL impulse noise monitor performance monitoring history data | +| 325 | xDSL line inventory and status data part 5 | +| 326 | xDSL line inventory and status data part 6 | +| 327 | xDSL line inventory and status data part 7 | +| 328 | RE common amplifier parameters | +| 329 | Virtual Ethernet interface point | +| 330 | Generic status portal | +| 331 | ONU-E | +| 332 | Enhanced security control | +| 333 | MPLS pseudowire termination point | +| 334 | Ethernet frame extended PM | +| 335 | SNMP configuration data | +| 336 | ONU dynamic power management control | +| 337 | PW ATM configuration data | +| 338 | PW ATM performance monitoring history data | +| 339 | PW Ethernet configuration data | +| 340 | BBF TR-069 management server | +| 341 | GEM port network CTP performance monitoring history data | +| 342 | TCP/UDP performance monitoring history data | +| 343 | Energy consumption performance monitoring history data | +| 344 | XG-PON TC performance monitoring history data | +| 345 | XG-PON downstream management performance monitoring history data | +| 346 | XG-PON upstream management performance monitoring history data | +| 347 | IPv6 host config data | +| 348 | MAC bridge port ICMPv6 process pre-assign table | +| 349 | PoE control | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|--------------------------------------------------------------| +| 350-399 | Reserved for vendor-specific use | +| 400 | Ethernet pseudowire parameters | +| 401 | Physical path termination point RS232/RS485 UNI | +| 402 | RS232/RS485 port operation configuration data | +| 403 | RS232/RS485 performance monitoring history data | +| 404 | L2 multicast GEM interworking termination point | +| 405 | ANI-E | +| 406 | EPON downstream performance monitoring configuration | +| 407 | SIP agent config data 2 | +| 408 | xDSL xTU-C performance monitoring history data part 2 | +| 409 | PTM performance monitoring history data xDSL | +| 410 | VDSL2 line configuration extensions 3 | +| 411 | Vectoring line configuration extensions | +| 412 | xDSL channel configuration profile part 2 | +| 413 | xTU data gathering configuration | +| 414 | xDSL line inventory and status data part 8 | +| 415 | VDSL2 line inventory and status data part 4 | +| 416 | Vectoring line inventory and status data | +| 417 | Data gathering line test, diagnostic and status | +| 418 | EFM bonding group | +| 419 | EFM bonding link | +| 420 | EFM bonding group performance monitoring history data | +| 421 | EFM bonding group performance monitoring history data part 2 | +| 422 | EFM bonding link performance monitoring history data | +| 423 | EFM bonding port performance monitoring history data | +| 424 | EFM bonding port performance monitoring history data part 2 | +| 425 | Ethernet frame extended PM 64 bit | +| 426 | Threshold data 64 bit | +| 427 | Physical path termination point UNI part 3 (FAST) | +| 428 | FAST line configuration profile part 1 | +| 429 | FAST line configuration profile part 2 | +| 430 | FAST line configuration profile part 3 | +| 431 | FAST line configuration profile part 4 | +| 432 | FAST channel configuration profile, part 1 | +| 433 | FAST data path configuration profile | +| 434 | FAST vectoring line configuration extensions | +| 435 | FAST line inventory and status data | + +**Table 11.2.4-1 – Managed entity identifiers** + +| Managed entity class value | Managed entity | +|-----------------------------------|----------------------------------------------------------------| +| 436 | FAST line inventory and status data part 2 | +| 437 | FAST xTU-C performance monitoring history data | +| 438 | FAST xTU-R performance monitoring history data | +| 439 | OpenFlow config data | +| 440 | Time Status Message | +| 441 | ONU3-G | +| 442 | TWDM System Profile managed entity | +| 443 | TWDM channel managed entity | +| 444 | TWDM channel PHY/LODS performance monitoring history data | +| 445 | TWDM channel XGEM performance monitoring history data | +| 446 | TWDM channel PLOAM performance monitoring history data part 1 | +| 447 | TWDM channel PLOAM performance monitoring history data part 2 | +| 448 | TWDM channel PLOAM performance monitoring history data part 3 | +| 449 | TWDM channel tuning performance monitoring history data part 1 | +| 450 | TWDM channel tuning performance monitoring history data part 2 | +| 451 | TWDM channel tuning performance monitoring history data part 3 | +| 452 | TWDM channel OMCI performance monitoring history data | +| 453 | Enhanced FEC performance monitoring history data | +| 454 | Enhanced TC performance monitoring history data | +| 455 | Link aggregation service profile | +| 456 | ONU manufacturing data | +| 457 | ONU time configuration | +| 458 | IP host performance monitoring history data part 2 | +| 459 | ONU operational performance monitoring history data | +| 460 | ONU4-G | +| 461 | BBF TR-369 USP agent | +| 462 | FAST channel configuration profile, part 2 | +| 463 | FAST line failures performance monitoring data | +| 464 | Synchronous Ethernet operation | +| 465 | Precision Time Protocol | +| 466 | Precision Time Protocol status | +| 467-65279 | Reserved for future standardization | +| 65280-65535 | Reserved for vendor-specific use | + +### **11.2.5 Message contents length, extended message format** + +These 2 bytes contain the length, in bytes, of the message contents field. Its value lies between 0 and 1966, for a 1980 byte PDU limit. + +To specify this range, 11 bits suffice. The five MSBs of this field are reserved for future use. + +From time to time, new parameters may be added to OMCI messages. The rules for the extended message set are as follows. + +- For backward compatibility, any new field must be added at the end of the OMCI message, they must be optional (and be documented as such) with the default value 0 that has backward compatible semantics. +- Trailing optional fields in a message may be omitted or included at the option of the transmitting device. The transmitting device sets the message content length field accordingly. +- The receiving device should not reject the message on the grounds of unexpected message content length. +- A receiving device that does not support the optional trailing fields should ignore them. +- The OLT must be prepared to accept a response based on the premise that the ONU does not support the optional fields, whether the optional fields are in the transmitted command message or in the received response message or both. In such a case, the value in the received response message content length field will be lower than expected. + +### **11.2.6 Message contents** + +The layout of the message content field is specific to each MT. The detailed layout of all messages appears in Annex A. + +### **11.2.7 OMCI trailer, baseline message format** + +The 8 bytes of this field are based on the AAL5 trailer definition: + +- a) The first 2 bytes correspond to common part convergence sublayer user-to-user (CPCS-UU) and CPI. They are set to 0 at the transmitter and ignored at the receiver. +- b) The length of the common part convergence sublayer service data unit (CPCS-SDU) field is set to 0x0028 (40 decimal). +- c) In ITU-T G.984 applications, the MIC is a 32 bit CRC as specified in [ITU-T I.363.5]. In ITU-T G.987 applications, the MIC is as specified in [ITU-T G.987.3]. + +### **11.2.8 MIC, extended message format** + +The integrity of an extended format OMCI message is verified by this 4 byte field. In ITU-T G.984 systems, the MIC is a 32 bit CRC as specified in [ITU-T I.363.5]. In subsequent PON systems the MIC calculation is defined in the respective TC layer specification. + +### **11.2.9 Message limits** + +Baseline OMCI messages impose limits on the size of attributes. Table 11.2.9-1 lists the important limits. + +**Table 11.2.9-1 – OMCI baseline message limitations** + +| Item | Limited by | Maximum size, bytes | +|----------------------------------------------------------|---------------------------|---------------------| +| Total size of set-by-create attributes (including ME ID) | Create | 34 | +| Size of (R) or (R,W) simple attribute | Get response | 25 | +| Size of (R) or (R,W) structured table entry (Note) | Set | 30 | +| Total size of a get | Get response | 25 | +| Total size of a get current data | Get current data response | 25 | + +NOTE – A structured table is one that contains distinct and separable rows, each row of which has the same syntax as the others. Long strings of bytes are also designated tables in clause 9, because the mechanism for retrieval is the same: get, followed by a number of get next commands. Such a byte string could be regarded as a table with but a single row, the length of which is limited only by the number of get next commands that can be specified. There is no way to set a value into such a byte string, however, so these attributes are necessarily read-only. + +Extended messages are limited by the total size of the PDU, and there is no possibility that a get or set or create message, even with a maximum number (16) of maximum length (25 byte) attributes, can exceed the message size limit. For backward compatibility, attribute definitions remain within the size limits of baseline messages, but a single extended message may contain more attributes than a baseline message. + +In cases where compatibility with [ITU-T G.984.4] is not required, future MEs are not intrinsically subject to these constraints. However, the evolution of common code encourages that attributes longer than 25 bytes be designated as table attributes, and that the get and get-next sequence be used to retrieve tables. + +The following considerations apply to baseline messages only. The larger PDU eliminates the possibility of message length violation in the extended message set. + +It is important that OLT and ONU implementations take size limits into account. For example, it is easy to form a (baseline) get command that asks the ONU to return more attributes than can fit into a (baseline) get response message. If the OLT asks for too many attributes in a get request, the ONU may respond with as many attributes as fit into the space available. From the attribute-present mask, the OLT can parse the attributes that were sent correctly, and can issue another get to retrieve the attributes that did not fit. + +While this is the preferred behaviour, an alternate interpretation is that the ONU returns a parameter error code when it receives a (baseline) get request whose response does not completely fit into one (baseline) get response message. For the sake of interoperability, the expected behaviour between an OLT and ONU with different interpretations is provided as follows. + +Case 1. The ONU reports a parameter error, and the OLT expects a partial list. If this happens, the OLT should react by simplifying its get request. The ONU then responds without an error. + +Case 2. The ONU provides a partial list, while the OLT expects to get an error. The OLT receives a normal message and processes it normally. The OLT asks again for any attributes it did not get. + +### 11.2.10 Test result enumeration + +Test actions can return measurements of various physical parameters in vendor-specific ways. Table 11.2.10-1 identifies parameters that may be of interest, with enumerated values to represent them in the test response message defined in Annex A. + +The resolution shown in the following descriptions merely indicates the weight attached to the LSB, and is not intended to impose requirements for precision or accuracy of the measured value. + +**Table 11.2.10-1 – Codes to represent measured values** + +| Type | Parameter | Representation | +|---------|---------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------| +| 1 | Power feed voltage, V | DC voltage, 2s complement, 20 mV resolution | +| 2 | Low voltage, V | DC voltage, 2s complement, 100 $\mu$ V resolution | +| 3 | Received optical power, dB | dB $\mu$ W, 2s complement, 0.002 dB resolution | +| 4 | Received optical power, W | Power, unsigned integer, 0.1 $\mu$ W resolution | +| 5 | Transmitted optical power, dB $\mu$ W | dB $\mu$ W, 2s complement, 0.002 dB resolution | +| 6 | Transmitted optical power, W | Power, unsigned integer, 0.1 $\mu$ W resolution | +| 7 | Video level, dBmV | dBmV, 2s complement, 0.002 dB resolution | +| 8 | Video level, V | RF voltage, unsigned integer, 200 $\mu$ V resolution. May be filtered or weighted in accordance with vendor-specific needs. | +| 9 | Laser bias current | Unsigned integer, 2 $\mu$ A resolution | +| 10 | Received voice signal quality measure Q | Unsigned integer, resolution 0.1 | +| 11 | Signal-to-noise ratio, dB | Unsigned integer, resolution 0.1 dB | +| 12 | Temperature, degrees C | 2s complement, 1/256 degree C resolution | +| 13..239 | Reserved for future standardization | | +| 240-254 | Not to be standardized. Available for vendor use. | | +| 255 | Reserved | Indicates an unavailable field in an ordered list of response values. | + +# Annex A + +## OMCI message syntax and common features + +(This annex forms an integral part of this Recommendation.) + +## A.1 General + +### A.1.1 Result and reason + +Responses to commands can indicate the result of the command. A zero value indicates that the command was processed successfully. Non-zero values indicate the reason for the failure. If the result was failure, the rest of the message contents may provide details of the failure, may be filled with all 0, or in the extended message set, may simply be omitted. The definition of each result and reason appears in Table A.1.1-1. + +**Table A.1.1-1 – Result and reason codes** + +| Code | Headline | Description | +|------|---------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0000 | Command processed successfully | There are two functions for command processing: command interpretation and command execution. This result means that the received command, such as get/set/test/reboot, was properly interpreted by the ONU's command interpretation function without errors and that the interpreted command was successfully transferred to the ONU's command execution function. | +| 0001 | Command processing error | This result means the command processing failed at the ONU for reasons not described by one of the more specific error codes. | +| 0010 | Command not supported | This result means that the message type indicated in byte 3 is not supported by the ONU. | +| 0011 | Parameter error | This result means that the command message received by the ONU was errored. It would be appropriate if an attribute mask were out of range, for example. In practice, this result code is frequently used interchangeably with code 1001. However, the optional attribute and attribute execution masks in the reply messages are only defined for code 1001. | +| 0100 | Unknown managed entity | This result means that the managed entity class (bytes 5..6) is not supported by the ONU. | +| 0101 | Unknown managed entity instance | This result means that the managed entity instance (bytes 7..8) does not exist in the ONU. | +| 0110 | Device busy | This result means that the command could not be processed due to process-related congestion at the ONU. This result code may also be used as a pause indication to the OLT while the ONU conducts a time-consuming operation such as storage of a software image into non-volatile memory. | +| 0111 | Instance exists | This result means that the ONU already has a managed entity instance that corresponds to the one the OLT is attempting to create. | + +**Table A.1.1-1 – Result and reason codes** + +| Code | Headline | Description | +|------|--------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1001 | Attribute(s) failed or unknown |

This result means that an optional attribute is not supported by the ONU or that a mandatory/optional attribute could not be executed by the ONU, even if it is supported, e.g., because of a range or type violation. In conjunction with this result, attribute masks are used to indicate which attributes failed or were unknown.

Two kinds of attribute masks are used when this result/reason is raised:

  • • optional attribute mask coding, which indicates whether the optional attribute is supported;
  • • attribute execution mask coding, which indicates whether the mandatory/optional attribute was executed.

See the set response and get response message layouts (see clauses A.2.6, A.3.6, A.2.8 and A.3.8) for the placement of these masks.

If one or more optional attributes are not supported by the ONU, the optional attribute mask coding for each unsupported optional attribute becomes 1 while the corresponding attribute execution mask coding remains 0.

If one or more mandatory or optional attributes were not executed by the ONU, the optional attribute mask coding remains 0, while the attribute execution mask coding becomes 1 for each failed attribute.

If the ONU could not latch copies of all specified table attributes, e.g., because of insufficient memory, the attribute execution mask is set to 1 for each attribute that does not have a latched copy available for get next retrieval.

| + +When the result-reason code in a response message indicates an exception (i.e., its value is not 0), the response message is permitted to include vendor-specific additional information. The rules for additional error information are as follows. + +1. Additional error information is optional for the ONU to insert. +2. Additional information may or may not be represented in textual form. +3. The semantics of additional error information are specific to the ONU vendor. +4. The ONU must not rely on the OLT being able to detect or interpret additional error information. +5. Additional error information may occupy only padding bytes (baseline message set) or only uncommitted trailing bytes (extended message set). +6. In get, get current data and get next responses, the attribute mask controls the padding definition. +7. No additional error information is permitted in responses to start download and end download messages that are directed to multiple target MEs, as indicated by 0xFFFF in the target ME identifier. + +These rules are defined with a view to maximizing the simplicity of an implementation. + +### A.1.2 Table attributes + +Normal attributes are coded such that they do not exceed the maximum OMCI attribute size, as limited by the baseline message format. However, there are cases where attributes need to be larger because they comprise arrays of data. In other cases, the attribute may be unstructured, but nevertheless be too large to be represented as a conventional attribute. Both types of large attributes are known as tables, and can be identified by the word *table* in their names. + +A table entry may be short enough that more than one row would fit into a (baseline) set command. However, the set command has no deterministic way to specify how many such rows are present. Therefore, the set action is permitted to set only a single entry in the table, the size of which is specified in clause 9 for the particular attribute in question. + +The set operation on a table row is possible only when individual table entries have a fixed size that does not exceed the maximum that can be conveyed in the (baseline) set message. A table attribute with variable-length rows or longer fixed-length rows is restricted to being read-only. + +NOTE 1 – Future managed entity definitions may relax the attribute size restrictions if baseline message set compatibility is not required. This is a matter for further study. + +An optional set table command is defined in the extended message set. Functionally, the set table command is the equivalent of an ordered sequence of set commands, each directed to the same table attribute of a given managed entity. As with the set command, table rows must have a fixed length, and because of the backward compatibility requirement, no table row may exceed the baseline length limit. + +The actual size of any given table attribute instance at any given time may be smaller than the OMCI single-message limit. Regardless of its actual size, however, the following sequence governs the retrieval of all table attributes. + +Figure A.1.2-1 shows how the OLT retrieves a table attribute. The OLT sends a get command, just as for any other attribute. The ONU latches a copy of the table for the anticipated get next sequence. In the get response, the ONU returns, not the value of the table attribute, but a 4 byte field containing the table's size, expressed in bytes. + +NOTE 2 – Zero is a valid size for many table attributes. + +The OLT then requests the attribute data from the ONU via the appropriate number of get next commands. There is no structure in the get next response; it simply regards the table as a byte string. + +![Sequence diagram showing the interaction between OLT and ONU to get a table attribute. The OLT requests the size, then uploads the attribute in chunks using 'get next' commands. The ONU responds with the size and then the data chunks. Two notes indicate that during the 'get next' sequence, the ONU can send AVCs and the OLT can send configuration commands.](3ba7b01a4ad082fa3e585e0945b135d2_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT requests size of a table attribute. + OLT->>ONU: Get (ME (table attribute)) + Note right of ONU: The ONU makes a copy of the attribute and returns the size of the copy in bytes. + ONU->>OLT: Get response (table attribute size) + Note left of OLT: The OLT uploads table attribute through an appropriate number of get next commands. + OLT->>ONU: Get next (ME (table attribute, sequence = 0)) + ONU->>OLT: Get next response (first N bytes of table) + Note right of ONU: During the get next sequence, the ONU can send AVCs. The OLT records the update in its image of the ONU's state. + Note left of OLT: During the get next sequence, the OLT can send configuration commands. The ONU updates its MIB or its state and responds to the OLT. These commands do not affect the copy of the table attribute being uploaded. + OLT->>ONU: Get next (ME (table attribute, sequence = k [Note])) + ONU->>OLT: Get next response (final M bytes of table) + +``` + +G.988(12)\_FA.1.2-1 + +Sequence diagram showing the interaction between OLT and ONU to get a table attribute. The OLT requests the size, then uploads the attribute in chunks using 'get next' commands. The ONU responds with the size and then the data chunks. Two notes indicate that during the 'get next' sequence, the ONU can send AVCs and the OLT can send configuration commands. + +NOTE –The number of get next commands, $k + 1$ , is derived by the OLT to retrieve the complete table. For baseline OMCI messages, each get next response contains 29 bytes; for extended OMCI messages, up to 1966 bytes (1980 maximum PDU size – 14 bytes of OMCI header) are returned in a full-length response. + +**Figure A.1.2-1 – Get a table attribute** + +The OLT issues as many get next requests as are needed to accommodate the size of the table attribute. As illustrated in Figure A.1.2-2, the ONU returns a parameter error response if the OLT overruns the size of the table attribute copy. + +![Sequence diagram showing the OLT overrunning the table attribute size. After receiving the final data chunk, the OLT erroneously issues another 'get next' command. The ONU responds with a 'parameter error'.](9d2498040386ba29e28ca79944c7e56a_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + OLT->>ONU: Get (ME (table attribute)) + ONU->>OLT: Get response (table attribute size) + OLT->>ONU: Get next (ME (table attribute, sequence = 0)) + ONU->>OLT: Get next response (first N bytes of table) + OLT->>ONU: Get next (ME (table attribute, sequence = k)) + ONU->>OLT: Get next response (final M bytes of table) + Note left of OLT: The OLT erroneously issues an additional get next command. + OLT->>ONU: Get next (ME (table attribute, sequence = k)) + ONU->>OLT: Get next response (result-reason 0011 = parameter error) + +``` + +G.988(12)\_FA.1.2-2 + +Sequence diagram showing the OLT overrunning the table attribute size. After receiving the final data chunk, the OLT erroneously issues another 'get next' command. The ONU responds with a 'parameter error'. + +**Figure A.1.2-2 – OLT overruns table attribute size** + +The maximum time between two get next requests is 60 s. If the OLT does not send a get next request within 60 s of the previous get next request or after the initial get request, the ONU assumes the get attribute transaction has terminated, discards its copy of the table attribute, and denies further get next requests directed to that attribute, again with a parameter error result-reason code. + +Capturing snapshots of multiple large tables could exhaust the limited memory resources of the ONU. Within any one ONU, the OLT should get and get-next only one table attribute at a time. If more than one table attribute is selected in the get command attribute mask, the ONU may reject the command with an attributes failed or unknown result-reason code. + +If more than one bit is set in the get-next command attribute mask or if the specified attribute is not a table, the ONU should respond with a parameter error result code. + +In each get next command, the OLT generates a sequence number, starting from 0. The sequence number resets to 0 for each attribute, even if successive attributes are part of the same ME parent. + +### A.1.3 Get, get response, create response and set messages + +For an attribute mask, a bit map is used in the get, get response, create response and set messages. This bit map indicates which attributes are requested (get) or provided (get response and set). The bit map is composed as follows. + +| Byte | Bit | | | | | | | | +|------|-------------|--------------|--------------|--------------|--------------|--------------|--------------|--------------| +| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| 1 | Attribute 1 | Attribute 2 | Attribute 3 | Attribute 4 | Attribute 5 | Attribute 6 | Attribute 7 | Attribute 8 | +| 2 | Attribute 9 | Attribute 10 | Attribute 11 | Attribute 12 | Attribute 13 | Attribute 14 | Attribute 15 | Attribute 16 | + +Attribute numbers correspond to the ordering of the attributes in clause 9. The ME identifier, which is an attribute of each ME, has no corresponding bit in the attribute mask. Thus, attributes are counted starting from the first attribute after the ME identifier. + +### A.1.4 Alarm notifications + +The ONU sends this notification each time an alarm status changes for the entity indicated in the ME identifier message field. The message shows the status of all alarms of this entity. It is up to the OLT to determine which alarm status has changed. The alarm message also reports declarations and cancellations of PM TCAs. + +The maximum number of alarms supported by the OMCI for a given ME instance is 224, because of the available message field of the baseline get all alarm next message. The bit map is composed as follows. + +| Byte | Bit | | | | | | | | +|------|-----------|-----------|-----------|-----------|-----------|-----------|-----------|-----------| +| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | +| 1 | Alarm 0 | Alarm 1 | Alarm 2 | Alarm 3 | Alarm 4 | Alarm 5 | Alarm 6 | Alarm 7 | +| 2 | Alarm 8 | Alarm 9 | Alarm 10 | Alarm 11 | Alarm 12 | Alarm 13 | Alarm 14 | Alarm 15 | +| ... | | | | | | | | | +| 28 | Alarm 216 | Alarm 217 | Alarm 218 | Alarm 219 | Alarm 220 | Alarm 221 | Alarm 222 | Alarm 223 | + +Alarm numbers correspond to the alarm coding or threshold coding in clause 9 (no ME class declares both alarms and TCAs). Bits in the alarm bit map that correspond to non-existing alarms are always set to 0. Bits that correspond to defined alarms are set to 0 to indicate that the corresponding alarm is cleared or to 1 to indicate that the alarm is currently active. + +Alarm message sequence numbers can take values in the interval 1 to 255. Zero is excluded in order to make this counter similar to the MIB data sync counter. + +#### A.1.4.1 Alarm sequence number increase + +The ONU informs the OLT of alarm status changes by sending alarm status change notifications. These notifications are sent in unacknowledged messages that carry an 8 bit alarm sequence number so that the OLT can detect loss of alarm notifications. Use cases are illustrated in Figures A.1.4.1-1 to A.1.4.1-3. + +After a restart of the ONU, the alarm sequence number is reset, so that the first alarm notification sent by the ONU will have an alarm sequence number equal to 1. The alarm sequence number is incremented for each alarm notification and wraps around from 255 to 1. No alarm notification ever has the sequence number 0. + +![Sequence diagram showing the increment of alarm sequence number at the ONU and OLT.](c06fd57bdcdb1e7e228a47ce7f899177_img.jpg) + +This sequence diagram illustrates the process of incrementing the alarm sequence number. It features two vertical lifelines for OLT and ONU. The ONU initiates the process with a message 'Alarm [any ME] (instance, alarm mask)' to the OLT. Above this message, a text box indicates that a fault occurs, the ONU updates its alarm table, increments the alarm sequence number, and sends the notification. Upon receiving the message, the OLT updates its own alarm table and sequence number. A text box below the OLT's lifeline states that the alarm tables in both the OLT and ONU are now aligned. The diagram is labeled G.988(12)\_FA.1.4.1-1. + +Sequence diagram showing the increment of alarm sequence number at the ONU and OLT. + +Figure A.1.4.1-1 – Increment of alarm sequence number at the ONU and OLT + +![Sequence diagram showing the alarm sequence number failing to stay in sync.](f57a7ecba2a6e188eb2a89f869152044_img.jpg) + +This sequence diagram shows a scenario where the alarm sequence number fails to stay in sync. Similar to the first diagram, it has OLT and ONU lifelines. The ONU sends an 'Alarm [any ME] (instance, alarm mask)' message to the OLT. A text box above the ONU indicates that a fault occurs, the alarm table is updated, and the sequence number is incremented, but the ONU is unable to send the notification to the OLT. The message arrow from the ONU to the OLT is marked with a large 'X', indicating it is lost. Below the OLT's lifeline, a text box notes that the alarm tables are not aligned and will only become aligned after an alarm resynchronization process. The diagram is labeled G.988(12)\_FA.1.4.1-2. + +Sequence diagram showing the alarm sequence number failing to stay in sync. + +Figure A.1.4.1-2 – Alarm sequence number fails to stay in sync + +When alarms are suppressed by ARC (clause A.1.4.3), the alarm is recorded by the ONU, but no alarm message is sent. Therefore, the alarm sequence number is not incremented. + +![Sequence diagram showing a fault occurring at the ONU without incrementing the alarm sequence number or notifying the OLT.](4e3b813e7d14508be44d187387c824d5_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: A fault occurs. The ONU updates its alarm table but does not increment its alarm sequence number. The ONU does not send an alarm notification to the OLT. + +``` + +G.988(12)\_FA.1.4.1-3 + +Sequence diagram showing a fault occurring at the ONU without incrementing the alarm sequence number or notifying the OLT. + +**Figure A.1.4.1-3 – No increment of alarm sequence number at the ONU and OLT under ARC** + +#### A.1.4.2 Alarm audit and resynchronization + +At initialization, periodically or when the OLT detects a gap in the alarm sequence number, it reconciles its view of the ONU's alarm status by sending a get all alarms command targeted at the ONU data ME, as shown in Figure A.1.4.2-1. + +When it receives the get all alarms request, the ONU resets the alarm sequence number to zero. + +If the OLT sets the alarm retrieval mode indicator in the get all alarms command to 1, the ONU only returns alarms that are not currently under ARC. Otherwise, the ONU returns all alarms regardless of ARC status. In accordance with this request option, the ONU creates a copy of its current alarm status table. ME instances with no reportable alarms are not represented in this copy. + +The ONU responds to the OLT with the number of get all alarms next commands required to retrieve the alarm status table copy (baseline message set) or the number of ME instances to be retrieved (extended message set). These are in fact the same value because each baseline message returns the alarm mask from one ME instance. The OLT then uploads the copy via a sequence of get all alarms next commands targeted at the ONU data ME. + +During the upload, the ONU is permitted to issue alarm notifications, both to declare and to clear alarms. + +When the upload is complete, the OLT compares the received alarm statuses with its own alarm table entries for that ONU, along with any alarm notifications received during the upload process, and notifies the network manager of any changes. + +![Sequence diagram illustrating the Alarm resynchronization process between an OLT and an ONU. The process starts with the OLT sending a 'Get all alarms (ONU data)' request to the ONU. The ONU responds with a box stating it resets the alarm sequence number to 0, makes a snapshot of the current alarm status table, and responds with N, the number of 'get all alarms next' commands needed. The OLT then creates a blank alarm status table and uploads the ONU's alarm status table copy with N 'get all alarms next' requests. The OLT sends 'Get all alarms next (ONU data (command sequence 0))' to the ONU, which responds with 'Get all alarms next response (ONU data (partial alarms snapshot, 0))'. A note indicates that during this process, the ONU can still send alarm notifications, and the OLT is responsible for reconciling them. The OLT then sends 'Get all alarms next (ONU data (command sequence N-1))' to the ONU, which responds with 'Get all alarms next response (ONU data (partial alarms snapshot, N-1))'. A note indicates that one minute after the last request, the ONU discards the alarm snapshot. Finally, the OLT reconciles the newly uploaded snapshot with its previous alarm state information and any new notifications.](286f86d91769a04cd4e5e314f1684ed9_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: The ONU resets the alarm sequence number to 0. The ONU makes a snapshot (copy) of the current alarm status table of all managed entity instances. + Note right of ONU: The ONU responds to the OLT's request with N, the number of get all alarms next commands needed to retrieve the alarm status snapshot. + OLT->>ONU: Get all alarms (ONU data) + ONU-->>OLT: Get all alarms response (ONU data, N) + Note left of OLT: The OLT creates a blank alarm status table for a later audit against its current view. The OLT then uploads the ONU's alarm status table copy with N get all alarms next requests. + OLT->>ONU: Get all alarms next (ONU data (command sequence 0)) + ONU-->>OLT: Get all alarms next response (ONU data (partial alarms snapshot, 0)) + Note right of ONU: During the alarm resynchronization process, the ONU can still send alarm notifications. The OLT is responsible for reconciling interim notifications against the static snapshot uploaded from the ONU. + OLT->>ONU: Get all alarms next (ONU data (command sequence N-1)) + ONU-->>OLT: Get all alarms next response (ONU data (partial alarms snapshot, N-1)) + Note right of ONU: One minute after the last get all alarms next command, the ONU discards alarms snapshot. + Note left of OLT: The OLT reconciles the newly uploaded snapshot with its previous alarm state information and with any newly received alarm notifications. + +``` + +Sequence diagram illustrating the Alarm resynchronization process between an OLT and an ONU. The process starts with the OLT sending a 'Get all alarms (ONU data)' request to the ONU. The ONU responds with a box stating it resets the alarm sequence number to 0, makes a snapshot of the current alarm status table, and responds with N, the number of 'get all alarms next' commands needed. The OLT then creates a blank alarm status table and uploads the ONU's alarm status table copy with N 'get all alarms next' requests. The OLT sends 'Get all alarms next (ONU data (command sequence 0))' to the ONU, which responds with 'Get all alarms next response (ONU data (partial alarms snapshot, 0))'. A note indicates that during this process, the ONU can still send alarm notifications, and the OLT is responsible for reconciling them. The OLT then sends 'Get all alarms next (ONU data (command sequence N-1))' to the ONU, which responds with 'Get all alarms next response (ONU data (partial alarms snapshot, N-1))'. A note indicates that one minute after the last request, the ONU discards the alarm snapshot. Finally, the OLT reconciles the newly uploaded snapshot with its previous alarm state information and any new notifications. + +**Figure A.1.4.2-1 – Alarm resynchronization** + +G.988(12)\_FA.1.4.2-1 + +The ONU allows 1 min between two get all alarms next requests. If the OLT does not send a get all alarms next request within this time after the previous get all alarms next request or after the get all alarms request, the ONU assumes the alarm upload to be terminated. It then discards the copy of the alarm table and considers any further get all alarms next requests to be out of range. + +#### A.1.4.3 Alarm-reporting control + +ARC allows for the suppression of alarms from PPTPs and cardholders, under the control of the management system. ARC suppresses alarm-reporting on the parent ME and all dependent entities, but does not suppress alarm conditions themselves. Therefore, if an alarm condition develops during an ARC interval, the ONU should maintain the internal indication of the alarm, and if the OLT gets all alarms regardless of ARC, it should be reported. + +[ITU-T M.3100] completely describes ARC from a generic viewpoint. The OMCI provides for ARC functions using two attributes of the parent ME: ARC and ARC interval. These two attributes are described below. + +##### Alarm-reporting control + +This attribute allows the activation of ARC for this PPTP or cardholder. The attribute works in concert with the ARC interval attribute. The value 0 disables ARC, while the value 1 enables ARC. The default value is disabled. When the ARC attribute is set to disabled, the PPTP or cardholder is in the ITU-T M.3100 ALM state, in which alarms are reported normally. When the ARC attribute is set to + +enabled, the PPTP or cardholder is in the ITU-T M.3100 NALM-QI state, in which alarm reporting is suppressed. + +The PPTP or cardholder moves from state ALM to state NALM-QI when the OLT changes the ARC attribute to enabled. The PPTP or cardholder moves from the NALM-QI state to the ALM state when either the PPTP or cardholder is trouble-free and the ARC interval timer expires or the ARC attribute is set to disabled by the OLT. Continuation or recurrence of a fault resets the timer. If the ARC interval timer expires, the ONU sets the ARC attribute to disabled autonomously, and sends an AVC to notify the OLT. Refer to [ITU-T M.3100] for a more extensive discussion. + +The ARC interval attribute can assume normal timing values of 0 to 254 min. The value 0 implies that a PPTP or cardholder in the NALM-QI state goes immediately to the ALM state upon detection of a problem-free state. An ARC interval value of 255 has the special meaning that the timer never expires. The PPTP or cardholder remains in the NALM-QI state until the OLT sets the ARC attribute to disabled. This behaviour is equivalent to the NALM state, which is another generic behaviour of the ARC function in [ITU-T M.3100]. + +The OMCI does not support the ITU-T M.3100 NALM-TI sub-function. + +##### **ARC interval** + +This attribute defines the interval to be used with the ARC function for this PPTP or cardholder. The values 0 to 254 give the duration in minutes for the NALM-QI timer of [ITU-T M.3100]. The special value 255 means that the timer never expires. The default value is zero. + +### **A.1.5 Test, test response and test result** + +This clause describes how test, test response and test result messages are related. + +- Test: This message is used to initiate either a self-test or any of the specific tests defined against various ME types. +- Test response: This message is the ONU's immediate AK of a test message. The test response message reports the ability of the ONU to run the required test, but it does not contain any specific results. A successful test response message implies that a test result message will be forthcoming in due course. +- Test result: This autonomous message is used to report the result of a self-test or one of the specific tests defined against various ME types. + +A test on a particular ME instance is invoked by sending a test message to this instance. Each ME that supports tests has a test action defined for it. The type of test invoked by a test message depends on the ME type. + +Figure A.1.5-1 shows the sequence of events when the OLT requests the ONU to perform a test. The OLT starts the test by sending a test command. The ONU acknowledges this command with a test response. Then the ONU carries out the test. After the test is complete, the ONU reports the test result via an autonomous test result notification. + +![Sequence diagram showing the reporting of test results between an OLT and an ONU. The OLT sends a 'Test command' to the ONU, which responds with a 'Test response'. A note indicates the ONU can still send AVCs. The ONU then carries out tests and reports results with a 'Test result notification'.](67babd1935daf7b3c4b0563e8158ee54_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT requests a test. + OLT->>ONU: Test command (ME type, instance, test selection) + ONU-->>OLT: Test response (ME type, instance, success) + Note right of ONU: The ONU can still send AVCs during the test operation. + Note right of ONU: The ONU carries out the requested tests and reports the results to the OLT. + ONU-->>OLT: Test result notification (ME type, instance, pass/fail[, details]) + +``` + +G.988(12)\_FA.1.5-1 + +Sequence diagram showing the reporting of test results between an OLT and an ONU. The OLT sends a 'Test command' to the ONU, which responds with a 'Test response'. A note indicates the ONU can still send AVCs. The ONU then carries out tests and reports results with a 'Test result notification'. + +**Figure A.1.5-1 – Reporting of test result** + +If the test was requested by the OLT, the test result notification contains the transaction identifier of the original test command. An ONU may also run continuing diagnostic or monitoring routines, and report failures either through alarms or through autonomous test result messages or both. A test result message from a self-initiated test contains the transaction identifier zero. + +### A.1.6 Administrative state considerations + +The administrative state attribute has two values: 0 (unlock) and 1 (lock). + +In the state model of [ITU-T X.731], administrative state represents the intention of management to allow (unlock) or deny (lock) the functionality of an ME. Administrative lock must not inhibit management access to the ME. Though specified by neither [ITU-T X.731] nor [ITU-T X.733], a common side effect of administrative lock is to suppress notifications from the locked entity and any dependent entities. This avoids unnecessary alarms during maintenance and repair, or when a resource is not in use. The OMCI conforms to this convention. + +The need for continuing management access implies that, regardless of the administrative state, an ONU must maintain its presence on the PON, and it may also have to provide local craft access, e.g., to enter registration information. + +Subject to continuing management access, it is suggested that the ONU itself, any separable circuit packs and all ports should power down as much as possible when the administrative state is locked. It is further suggested that the default value for administrative state be locked. This reduces power consumption in cases such as pre-installation of ONUs and unsubscribed or unused ports. + +Operators may have additional requirements that override power-down or that override the suggested lock default. + +NOTE – When an ITU-T G.987 ONU enters initial state, as defined in [ITU-T G.987.3], it may set administrative lock on the ONU-G ME, thereby preventing all user traffic from flowing until the OLT unlocks the ONU-G. Although this is optional behaviour on the part of the ONU, the OLT is advised to check the state of this attribute when bringing an ONU into service. + +## A.2 Extended message set + +The extended OMCI message set may be used by G-PON systems after initial start-up on the baseline message set. + +Extended OMCI messages may be up to 1980 bytes long, including headers. + +### A.2.1 Create + +The contents of the create message apply only to attributes that are defined to be set-by-create. Writeable attributes that are not set-by-create are not permitted in a create message. Thus, the first byte of the message contents field begins with the value of the first set-by-create attribute and so forth. Space for each set-by-create attribute must be allocated in the create message, even if the attribute is optional. When an optional attribute is not to be instantiated, the placeholder value to be entered into this space is specific to the definition of each attribute. If the ONU does not support a given optional set-by-create attribute, the ONU should simply ignore that field in the create message, and the ONU should not set an illegal value flag in the create message response. + +When the OMCI specifies a default value for a set-by-create attribute, the intention is that the OLT populate the default recommendation into the create message. The ONU is not responsible for instantiating any particular value for a set-by-create attribute. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = create | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11-n | | | | | | | | | Value of first set-by-create attribute,
NOT the ME ID (size depending on
the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of last set-by-create attribute | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.2 Create response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = create | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field =
3 bytes | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
0111 instance exists | +| | 12-13 | | | | | | | | | Attribute execution mask, used when result, reason = 0011
0 attribute ok
1 illegal attribute value | +| MIC | 14-17 | | | | | | | | | Message integrity check | + +NOTE – If the result, reason code is not 0011, the attribute execution mask in bytes 12-13 is omitted. + +### A.2.3 Delete + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = delete | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 0 | +| MIC | 11-14 | | | | | | | | | Message integrity check | + +### A.2.4 Delete response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = delete | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | | | | | | | | | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.5 Set + +As well as simple attributes, the set command may be used to set rows of tables. If it is used for this purpose, however, one set command must set exactly one row of the table, because there is no way to enumerate or separate multiple table entries. The set table command is available to set more than one row with a single command. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|--------------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = set | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11-12 | | | | | | | | | Attribute mask | +| | 13- n | | | | | | | | | Value of first attribute to set (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of last attribute to set | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.6 Set response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = set | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| | 12-13 | | | | | | | | | Optional-attribute mask, used with 1001 encoding:
0 default
1 unsupported attribute | +| | 14-15 | | | | | | | | | Attribute execution mask, used with 1001 encoding:
0 default
1 failed attribute | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +NOTE – The attribute masks in bytes 12-15 are present if, and only if, the result-reason code is 1001. + +### A.2.7 Get + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 bytes | +| Message contents | 11-12 | | | | | | | | | Attribute mask | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +### A.2.8 Get response + +Bytes 14-17 are always reserved for the optional-attribute and attribute execution masks; however, the contents of these bytes are only valid in conjunction with result code 1001 used to indicate failed or unknown attributes. When the result code is not 1001, these bytes should be set to 0 by the ONU transmitter and ignored by the OLT receiver. + +When the OLT wishes to retrieve a table attribute, i.e., an attribute whose size is, or might be, larger than the space available in one OMCI baseline message, the ONU indicates the size of that attribute in bytes, rather than its value. The size is conveyed as 4 bytes in the value field for that attribute, with the attribute execution mask set to indicate that the attribute is included. The OLT should then use a + +sequence of get next messages to retrieve such an attribute. This convention also pertains to extended OMCI messages, even though some table attributes might fit into an extended get response message. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| | 12-13 | | | | | | | | | Attribute mask | +| | 14-15 | | | | | | | | | Optional-attribute mask, used with 1001 encoding:
0 default
1 unsupported attribute | +| | 16-17 | | | | | | | | | Attribute execution mask, used with 1001 encoding:
0 default
1 failed attribute | +| | 18-n | | | | | | | | | Value of first attribute included (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of last attribute included | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.9 Get all alarms + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get all alarms | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| | 5-6 | | | | | | | | | Entity class = ONU data | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------| +| Managed entity identifier | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = alarm retrieval mode
0 Get all alarms regardless of ARC status
1 Get all alarms not currently under ARC | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.10 Get all alarms response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get all alarms | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 bytes | +| Message contents | 11-12 | | | | | | | | | Number of ME instances to be retrieved | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +### A.2.11 Get all alarms next + +Command sequence numbers start from 0. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get all alarms next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 bytes | +| Message contents | 11-12 | | | | | | | | | Command sequence number | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +### A.2.12 Get all alarms next response + +Note that alarm bit maps for a number of MEs may be returned within a single message. + +The bit map used in the get all alarms next response for a given ME class is identical to the bit map used in the alarm notification for that ME class. + +If the ONU receives a get all alarms next request message whose command sequence number is out of range, the get all alarms next response message should contain a null message contents field. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get all alarms next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field including all sub-parts, bytes | +| Message contents 1 | 11-12 | | | | | | | | | Entity class whose alarms are reported | +| | 13-14 | | | | | | | | | Entity instance whose alarms are reported | +| | 15-42 | x | x | x | x | x | x | x | x | Bit map alarms | +| Message contents 2 (as needed) | 43-44 | | | | | | | | | Entity class whose alarms are reported | +| | 45-46 | | | | | | | | | Entity instance whose alarms are reported | +| | 47-74 | x | x | x | x | x | x | x | x | Bit map alarms | +| ... | | | | | | | | | | Further managed entity alarm maps as needed | +| Message contents n | | | | | | | | | | | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.13 MIB upload + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB upload | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 0 | +| MIC | 11-14 | | | | | | | | | Message integrity check | + +### A.2.14 MIB upload response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|----------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB upload | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 bytes | +| Message contents | 11-12 | | | | | | | | | Number of MIB upload next commands required | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +### A.2.15 MIB upload next + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB upload next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 bytes | +| Message contents | 11-12 | | | | | | | | | Command sequence number | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +Command sequence numbers start from 0. + +### A.2.16 MIB upload next response + +Note that, if not all attributes of a ME fit within one MIB upload next response message, the attributes are split over several messages. The OLT can use the information in the attribute mask to determine which attribute values are reported in which MIB upload next response message. + +Thus, a single extended MIB upload next response message must contain an integer number of attribute values. A message may contain leading or trailing fragments of ME instance reports and any number of complete ME instance reports. + +If the ONU receives an MIB upload next request message whose command sequence number is out of range, it should respond with a message containing no message contents field. This is also the appropriate response if the ONU times out (one minute) from the most recent MIB upload next or MIB upload request from the OLT. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB upload next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------| +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field including all sub-fields, bytes | +| Message contents, ME instance 1 | 11-12 | | | | | | | | | Size of ME instance 1 attribute values included (excluding bytes 11-18), bytes | +| | 13-14 | | | | | | | | | Entity class of ME instance 1 | +| | 15-16 | | | | | | | | | Entity instance | +| | 17-18 | | | | | | | | | Attribute mask | +| | 19-n | | | | | | | | | Value of first attribute (size depending on the type of the attribute) | +| | | | | | | | | | | | +| | | | | | | | | | | Value of last attribute | +| Message contents, ME instance 2 | | | | | | | | | | Content of ME instance 2, defined as above. | +| | | | | | | | | | | | +| Message contents, ME instance k | | | | | | | | | | Content of ME instance k, defined as above. | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.17 MIB reset + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB reset | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 0 | +| MIC | 11-14 | | | | | | | | | Message integrity check | + +### A.2.18 MIB reset response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB reset | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.19 Alarm + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = alarm | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 29 bytes | +| Message contents | 11-38 | | | | | | | | | Alarm bit map | +| | 39 | | | | | | | | | Alarm sequence number | +| MIC | 40-43 | | | | | | | | | Message integrity check | + +### A.2.20 Attribute value change + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = attribute value change | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11-12 | | | | | | | | | Attribute mask | +| | 13-n | | | | | | | | | Value of first changed attribute (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of last changed attribute | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|---|---|---|---|---|---|---|---|----------------------------------| +| MIC | | | | | | | | | | Message integrity check, 4 bytes | +| NOTE – The AVC message for a table attribute does not contain an attribute value, only a mask, and the ONU does not create a snapshot of the table. If the OLT wishes to obtain the new value, it must do a get operation, followed by the required number of get next operations. | | | | | | | | | | | + +### A.2.21 Test + +The format of the test message is specific to the target entity class. Several formats are defined. Future test extensions for a given entity class can be supported by adding additional encodings to presently unused bits or bytes. Future specification of tests for other entity classes may use an existing format or may define new formats for the test message. These extension mechanisms allow future tests to be supported without changing the principle of operation. + +#### A.2.21.1 Format for ONU-G, ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier, RE downstream amplifier and circuit pack entity classes + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This format applies to entity classes ONU-G, ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier, RE downstream amplifier and circuit pack. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | xxxx = select test
0000..0110 Reserved for future use
0111 Self-test
1000..1111 Vendor-specific use.
See description related to the test result message. | +| | 12-13 | | | | | | | | | Pointer to a general purpose buffer ME, used to return vendor-specific test results.
This field is optional. The OLT may include this field, or in case it is not used, set it to zero. If the following field is not used or not supported, the OLT may omit both fields. The ONU should accept either option, ignoring the field if it does not support the feature. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 14-15 | | | | | | | | | Pointer to an octet string ME, used to define the vendor-specific test parameters.
This field is optional. The OLT may include this field, or in case it is not used, omit it or set it to zero. The ONU should accept either option, ignoring the field if it does not support the feature. | +| MIC | | | | | | | | | | Message integrity check | + +#### A.2.21.2 Format for IP host config data and IPv6 host config data entity classes + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This format applies to entity classes IP host config data and IPv6 host config data. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field – 5 bytes (IPv4 address) or 17 bytes (IPv6 address) | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | xxxx = select test
0001 Ping
0010 Traceroute
0011 Extended ping
0100..0111 Reserved
1000..1111 Vendor-specific use.
The ICMP message is intended to be sent from the ONU upstream towards the network. See discussion related to the test result message. | +| | 12-15 | | | | | | | | | Option 1: IPv4 address of target (zero if byte 11 specifies extended ping test) | +| | 12-27 | | | | | | | | | Option 2: IPv6 address of target (zero if byte 11 specifies extended ping test) | +| | 28 | | | | | | | | | Number of times to ping.
This field pertains to both explicit and extended ping tests. The value 0 or the absence of this field selects the ONU's internal default. | +| | 29-30 | | | | | | | | | Pointer to large string ME that identifies the target via a DNS-parsable string. This field is used only for the extended ping test. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|------|---|---|---|---|---|---|---|---|-------------------------| +| MIC | | | | | | | | | | Message integrity check | + +#### A.2.21.3 Format for PTP POTS UNI entity class + +The test message for POTS UNIs supports two basic categories of test operation, a defined set of tests that look in and out from the POTS port, and a set of code points that may be used for vendor-specific tests. The latter category is further subdivided into code points that return test results in a general purpose buffer ME, using the test result message primarily as an event trigger to signal test completion, and code points that return all test results in an ordinary test result message. If it is needed, the OLT must create the general purpose buffer ME before initiating the test action. + +Note that a single message can be used to initiate multiple tests on a given ME if desired. + +Bytes 12-25 are used by the dial tone make-break test. A zero value for a timer causes the ONU to use its built-in defaults. As many as three dial tone frequencies can be specified, or omitted by setting their values to 0. Other fields are also omitted with the value 0, or controlled by flags. An ONU can support the dial tone test with internal defaults only, and is not required to support any of the attributes of bytes 12-25. Likewise, an ONU can use internal defaults for a drop test, rather than the values given in bytes 26-35. The capabilities of an ONU are documented by the vendor and known through administrative practices. + +Several distinct test classes are defined. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This format applies to entity class PTP POTS UNI. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Message contents | 11 | x | 0 | t | t | x | x | x | x | tt selects one of the POTS test class formats
0 MLT, dial tone make-break
1 SIP/ITU-T H.248 test call
2..3 Reserved
x Bits reserved for use in specific test classes as defined below | + +##### **Test class 0:** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | a | 0 | 0 | 0 | x | x | x | x | a – test mode
0 normal; deny test if line busy
1 forced mode
xxxx = select test
0000 all MLTs
0001 hazardous potential
0010 foreign EMF
0011 resistive faults
0100 receiver off-hook
0101 ringer
0110 NT1 dc signature test
0111 self-test
1000 dial tone make-break test
1001..1011 vendor-specific test, all results returned in test results message
1100..1111 vendor-specific test, test results returned in general purpose buffer ME. The ONU should deny a test operation command in this range if bytes 36..37 do not point to a GP buffer. | +| | 12 | | | | | | | | | Draw-break dial tone (DBDT) timer T1 (slow dial tone threshold), in units of 0.1 s. Range 0.1 to 6.0 s. | +| | 13 | | | | | | | | | DBDT timer T2 (no dial tone threshold), in units of 0.1 s. Range 1.0 to 10.0 s. | +| | 14 | | | | | | | | | DBDT timer T3 (slow break dial tone threshold), in units of 0.1 s. Range 0.1 to 3.0 s. | +| | 15 | | | | | | | | | DBDT timer T4 (no break dial tone threshold), in units of 0.1 s. Range 1.0 to 3.0 s. | +| | 16 | | | | | | | d | p | DBDT control byte
d: dialled digit
1 dialled digit specified in byte 17
0 use default digit
p = pulse (1) or tone (0) dialling | +| | 17 | | | | | | | | | Digit to be dialled, ASCII character in range "0"-"9", "*", "#". | +| | 18-19 | | | | | | | | | Dial tone frequency 1, in hertz | +| | 20-21 | | | | | | | | | Dial tone frequency 2, in hertz. 0 = unused (i.e., if only one tone is specified). | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 22-23 | | | | | | | | | Dial tone frequency 3, in hertz. 0 = unused (i.e., if only one or two tones are specified). | +| | 24 | | | | | | | | | Dial tone power threshold, absolute value, 0.1 dB resolution, range [-]0.1 to [-]25.3 dBm0. E.g., -13 dBm0 = 0x82. 0 = unspecified. | +| | 25 | | | | | | | | | Idle channel power threshold, absolute value, 1 dB resolution, range [-]1 to [-]90 dBm0. 0 = unspecified. | +| | 26 | | | | | | | | | DC hazardous voltage threshold, absolute value, volts. 0 = unspecified. | +| | 27 | | | | | | | | | AC hazardous voltage threshold, volts RMS. 0 = unspecified. | +| | 28 | | | | | | | | | DC foreign voltage threshold, absolute value, volts. 0 = unspecified. | +| | 29 | | | | | | | | | AC foreign voltage threshold, volts RMS. 0 = unspecified. | +| | 30 | | | | | | | | | Tip-ground and ring-ground resistance threshold, kilohms 0 = unspecified. | +| | 31 | | | | | | | | | Tip-ring resistance threshold, kilohms. 0 = unspecified. | +| | 32-33 | | | | | | | | | Ringer equivalence minimum threshold, in 0.01 REN (ringer equivalent number) units. 0 = unspecified. | +| | 34-35 | | | | | | | | | Ringer equivalence maximum threshold, in 0.01 REN units. 0 = unspecified. | +| | 36-37 | | | | | | | | | Pointer to a general purpose buffer ME, used to return vendor-specific test results. | +| | 38-39 | | | | | | | | | Pointer to an octet string ME, used to define vendor-specific test parameters. This field is optional. The OLT may include this field, or in case it is not used, omit it or set it to zero. The ONU should accept either option, ignoring the field if it does not support the feature. | +| MIC | | | | | | | | | | Message integrity check | + +##### **Test class 1:** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------| +| Message contents | 11 | a | 0 | 0 | 1 | x | x | x | x | a – test mode
0 normal; deny test if line busy
1 forced mode
x Reserved | +| | 12-27 | | | | | | | | | ASCII string containing the number to be dialled. Trailing unused octets are padded with null bytes. | +| MIC | 28-31 | | | | | | | | | Message integrity check | + +#### **A.2.21.4 Format for dot1ag MEP entity class, loopback test** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to the dot1ag MEP entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 20 bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = select test
0: Ethernet loopback test
1: IEEE 802.1ag linktrace test (see separate format description below)
Other values reserved | +| | 12 | 0 | 0 | 0 | c | p | p | p | d | If c = 1, the value of the MEP's CCM and LTM priority attribute is used, with drop eligibility false.
If c = 0, pppd represents the priority (P bits) and drop eligibility fields of the transmitted LBM frame. | +| | 13-18 | | | | | | | | | MAC address of target MHF or MEP, or 0 if the destination MEP ID is to be used instead. [IEEE 802.1ag] specifies unicast addresses; [ITU-T Y.1731] also allows for multicast. | +| | 19-20 | | | | | | | | | Destination MEP ID, in the range 1..8191, or 0 if the MAC address in bytes 13..18 is to be used instead. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 21-22 | | | | | | | | | Repetition count, range 1..1024. This governs how many LBMs are generated. The rate at which LBMs are generated is not specified. If 5 seconds elapses with no LBRs received, the test aborts. | +| | 23-24 | | | | | | | | | These four fields are pointers to as many as 4 octet string MEs, which are concatenated to form an octet string of up to 1500 bytes. The string is packaged into a data TLV and transmitted as part of the LBM. If all four fields are null pointers, no data TLV is sent. If only one octet string is needed, it should be specified in bytes 23..24, etc., with null pointers in the higher-numbered bytes of the test message. | +| | 25-26 | | | | | | | | | | +| | 27-28 | | | | | | | | | | +| | 29-30 | | | | | | | | | | +| MIC | 31-33 | | | | | | | | | Message integrity check | + +#### A.2.21.5 Format for dot1ag MEP entity class, linktrace test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to the dot1ag MEP entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 13 bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = select test
0: Ethernet loopback test (see separate format description above)
1: IEEE 802.1ag linktrace test
Other values reserved | +| | 12 | f | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Flags, a bit map
f: Use FDB only . When 1, the bridge uses only its normal MAC forwarding tables for forwarding. When 0, the bridge may also consult its MIP CCM database to determine the forwarding port. | +| | 13-18 | | | | | | | | | Unicast MAC address of target MHF or MEP, or 0 if the destination MEP ID is to be used instead. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 19-20 | | | | | | | | | Destination MEP ID, in the range 1..8191, or 0 if the unicast MAC address in bytes 13..18 is to be used instead. | +| | 21 | | | | | | | | | Max hops count – specifies initial time to live (TTL); limits the number of relay stages through which the LTM is forwarded before being discarded, and the number of LTRs that may be returned. [IEEE 802.1ag] recommends a default value of 64. | +| | 22-23 | | | | | | | | | Pointer to a general purpose buffer ME, used to return the linktrace results. The ONU should deny the test operation command if this field is a null or an invalid pointer. | +| MIC | 24-27 | | | | | | | | | Message integrity check | + +### A.2.22 Test response + +If an ONU does not support all tests requested in byte 11 of the test request message, it should not execute any test and should respond with result 0010, command not supported. If an ONU supports all of the requested tests but cannot support one or more of the explicitly specified threshold attributes, it should not execute any test and should respond with result 0011, parameter error. The test command could then be re-issued with different thresholds or with default thresholds, and would be expected to succeed. + +The test response message is an indication to the OLT that the test request is received and is being processed. Test outcome is reported by a subsequent autonomous test result message. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.23 Start software download + +When a file is to be downloaded to a single instance of the software image ME, the target ME ID is specified in bytes 7..8. An optional feature permits the same file to be downloaded to a number of circuit packs by setting bytes 7..8 = 0xFFFF and specifying the software image ME IDs in bytes 17-18, 19-20, etc. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = start software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | | | | | | | | | Window size – 1 | +| | 12-15 | | | | | | | | | Image size in bytes | +| | 16 | | | | | | | | | Number of circuit packs to be updated in parallel (value 1..9) | +| | 17-18 | | | | | | | | | ME ID of software image entity instance (first byte: slot number; second byte: instance 0..1 or 2..254 vendor-specific) | +| | 19-20, etc. | | | | | | | | | Additional software image ME IDs (same format as bytes 17..18) for additional simultaneous downloads. | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.24 Start software download response + +When a file is downloaded to a single software image ME, the response contains the target ME ID in bytes 7..8, a result code in byte 11, and a window size counter-proposal (which may be the same as that suggested by the OLT in the original request) in byte 12. Bytes 13..N are omitted. + +An ONU that supports the optional parallel download feature responds to a multiple download command with the full format shown below, where unused trailing image references may be omitted. If the ONU does not support the parallel download feature, it responds with result code 0b0101, unknown ME instance. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = start software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 12 | | | | | | | | | Window size – 1 | +| | 13 | | | | | | | | | Number of instances responding (value 0..9) | +| | 14-15 | | | | | | | | | ME ID of software image entity instance (first byte: slot number; second byte: instance 0..1 or 2..254 vendor-specific) | +| | 16 | | | | | | | | | Result, reason for bytes 14..15 – same coding as byte 11 | +| | 17-n | | | | | | | | | Repeat coding of bytes 14..16 for additional requested software image instances. | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.25 Download section + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | x | 0 | | | | | | DB = 0, AR = x, AK = 0
x = 0 no response expected (section within a window)
x = 1 response expected (last section of a window)
bits 5-1: action = sw download section | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | | | | | | | | | Download section number | +| | 12-n | | | | | | | | | Software image data | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.26 Download section response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = sw download section | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 12 | | | | | | | | | Download section number | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +### A.2.27 End software download + +The format of this command is similar to that of the start software download message. Bytes 19..n support the optional parallel download feature, and are omitted for download to a single target. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = end software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11-14 | | | | | | | | | CRC-32, computed over all bytes of the software image (excluding padding), as specified in [ITU-T I.363.5]. | +| | 15-18 | | | | | | | | | Image size in bytes | +| | 19 | | | | | | | | | Number of parallel download instances sent in this message (value 1..9) | +| | 20-21 | | | | | | | | | ME ID of software image entity instance (first byte: slot number; second byte: instance 0..1 or 2..254 vendor-specific) | +| | 22-23, etc. | | | | | | | | | Software image ME IDs (same format as bytes 20..21) for additional simultaneous downloads. | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.28 End software download response + +The response message informs the OLT whether the download command was successful. If a single software image ME was targeted for download, byte 11 reports the result of the process, and bytes 12..N are omitted. If a number of software images were targeted for parallel download, byte 11 reports device busy as long as any of the instances is busy writing the image to a non-volatile store. Once the ONU has stored all images successfully, it responds to continued end software download commands with a 0 in byte 11 and a separate result for each software image ME. Unused trailing instance references may be omitted. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = end software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully (CRC correct)
0001 command processing error (CRC incorrect, in addition to the normal criteria)
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 12 | | | | | | | | | Number of instances responding (value 0..9) | +| | 13-14 | | | | | | | | | ME ID of software image entity instance (first byte: slot number; second byte: instance 0..1 or 2..254 vendor-specific) | +| | 15 | | | | | | | | | Result, reason for bytes 13..14 – same coding as byte 11 | +| | 16-n | | | | | | | | | Repeat coding of bytes 13..15 for additional software image instances. | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.29 Activate image + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = activate image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|----------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Flags (Note 1) | 11 | 0 | 0 | 0 | 0 | 0 | 0 | F | F | Bits FF:
00 Activate image unconditionally
01 Activate image only if no POTS/VoIP calls are in progress
10 Activate image only if no emergency call is in progress (Note 2)
11 Reserved
If the ONU denies the activate image command because of the FF field, it returns result, reason code 0110, device busy. | +| MIC | | | | | | | | | | Message integrity check | + +NOTE 1 – The Flags byte is optional. If it is absent, the activate image command is to be executed unconditionally. + +NOTE 2 – The ONU determines the presence of an originating emergency call on the basis of the Emergency service number attribute of the VoIP feature access codes ME. Other ways for the ONU to determine the presence of an emergency call are for further study. + +### A.2.30 Activate image response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = activate image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.31 Commit image + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = commit image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 0 | +| MIC | 11-14 | | | | | | | | | Message integrity check | + +### A.2.32 Commit image response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = commit image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|-------------------------| +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.33 Synchronize time + +The synchronize time command controls the tick boundary for PM collection, and optionally, a date and time clock. + +If this message specifies the time (and optionally the date), the ONU sets its PM interval counter to a current offset from the most recent quarter-hour boundary, i.e., to a value in the range 0..899 s. This may cause the current PM collection interval to be longer or shorter than 900 s. Date and time are not explicitly required in an ONU, but if the ONU has a real-time clock, it is also set by this message. If the OLT does not wish to specify a date, it may set year, month and day fields to 0. If the ONU does not support the setting of the date, it will use the success result info field in the synchronize time response message to indicate that only the 15 min tick boundary was set. + +If date and time are not present in the message, the ONU sets its PM interval counter to 0. This may cause the current PM collection interval to be shorter than 900 s. The effect on a possible ONU real-time clock is not specified. + +There is no intention that this message be used to establish a precise time of day reference. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = synchronize time | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU-G | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11-12 | | | | | | | | | Year, e.g., 2009 | +| | 13 | | | | | | | | | Month, range 1..12 | +| | 14 | | | | | | | | | Day of month, range 1..31 | +| | 15 | | | | | | | | | Hour of day, range 0..23 | +| | 16 | | | | | | | | | Minute of hour, range 0..59 | +| | 17 | | | | | | | | | Second of minute, range 0..59 | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.34 Synchronize time response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
Bits 5-1: action = synchronize time | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU-G | +| | 7-8 | | | | | | | | | Entity instance = 0 | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Message contents | 11 | x | x | x | x | r | r | r | R | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 12 | x | x | x | x | r | r | r | r | x: reserved
rrrr: Success result info
0000 15 min tick boundary set successfully
0001 Date and 15 min tick boundary set successfully
This byte is present and meaningful only when the result, reason code in byte 11 is 0000. Byte 12 is optional and is treated as described in clause 11.2.5. | +| MIC | | | | | | | | | | Message integrity check | + +### A.2.35 Reboot + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = reboot | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Flags (Note 1) | 11 | 0 | 0 | 0 | 0 | 0 | 0 | F | F | Bits FF:
00 Reboot unconditionally
01 Reboot only if no POTS/VoIP calls are in progress
10 Reboot only if no emergency call is in progress (Note 2)
11 Reserved
If the ONU denies the reboot command because of the FF field, it returns result, reason code 0110, device busy. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|------|---|---|---|---|---|---|---|---|-------------------------| +| MIC | | | | | | | | | | Message integrity check | + +NOTE 1 – The Flags byte is optional. If it is absent, the activate image command is to be executed unconditionally. +NOTE 2 – The ONU determines the presence of an originating emergency call on the basis of the Emergency service number attribute of the VoIP feature access codes ME. Other ways for the ONU to determine the presence of an emergency call are for further study. + +### A.2.36 Reboot response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = reboot | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | | | | | | | | | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.2.37 Get next + +The ONU should reject a get next command: + +- if the attribute mask specifies more than one attribute (result code 0011); +- if the attribute mask specifies an attribute that is not a table (result code 0011); +- if the specified attribute has not been prepared for upload with a prior get command (the prior get is subject to 1 min timeout) (result code 0001). + +Command sequence numbers start from 0. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| | 5-6 | | | | | | | | | Entity class | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------| +| Managed entity identifier | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 4 bytes | +| Message contents | 11-12 | | | | | | | | | Attribute mask | +| | 13-14 | | | | | | | | | Command sequence number | +| MIC | 15-18 | | | | | | | | | Message integrity check | + +### A.2.38 Get next response + +If the ONU receives a get next request message whose command sequence number is out of range, the ONU responds with parameter error. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 12-13 | | | | | | | | | Attribute mask | +| | 14-n | | | | | | | | | Value of the specified attribute (size depending on the type of attribute, limited by message capacity) | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +### A.2.39 Test result + +The test result message reports the outcome of a test. In the case of a requested test, the transaction identifier of the test result message is identical to the transaction identifier of the test message that initiated the corresponding test. In the case of a self-triggered test result, the transaction identifier is set to 0. + +Several formats are currently defined. They are used as follows: + +- self-test results, ONU-G, circuit pack, or any other ME that supports self-test; + +- vendor-specific test results, generic format, any ME that supports it; +- POTS test results, either an MLT, dial tone draw-break or vendor-specific POTS tests that use a general purpose buffer; +- ICMP tests, either ping or traceroute; +- the results of an optical line supervision test on the ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier or RE downstream amplifier; +- [IEEE 802.1ag] loopback and linktrace tests. + +If a new test for the currently supported entities is defined in the future, the corresponding test results can be reported by extending the test result message layout. If a new test for other ME classes is defined in the future, a new test result message layout may be defined. + +#### A.2.39.1 Format for self-test action invoked against ONU-G and circuit pack entity classes + +| Field | Byte | 8 7 6 5 4 3 2 1 | | | | | | | | Comments | +|------------------------------------|-------|-----------------|---|---|---|---|---|---|-------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This message format pertains to ONU-G and circuit pack entity classes. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Reserved | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | xx: self-test result
00 failed
01 passed
10 not completed | +| | 13-14 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer.
This field is optional. The ONU may include this field, or in case it is not used, omit it or set it to zero. The OLT should accept either option. | +| MIC | | | | | | | | | Message integrity check | | + +#### A.2.39.2 Format for vendor-specific test actions invoked against ONU-G and circuit pack entity classes + +This format is also used for vendor-specific test actions invoked against the PPTP POTS UNI entity class when no general purpose buffer is needed. + +| Field | Byte | 8 7 6 5 4 3 2 1 | | | | | | | | Comments | +|------------------------------------|------|-----------------|---|---|---|---|---|---|---|----------| +| | | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | | +| Transaction correlation identifier | 1-2 | | | | | | | | | | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------| +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This message format pertains to ONU-G, circuit pack and PPTP POTS UNI entity classes. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | | | | | | | | | Type 1 (Note) | +| | 12-13 | | | | | | | | | Value 1 | +| | 14 | | | | | | | | | Type 2 | +| | 15-16 | | | | | | | | | Value 2 | +| | 17 | | | | | | | | | Type 3 | +| | 18-19 | | | | | | | | | Value 3 | +| | 20 | | | | | | | | | Type 4 | +| | 21-22 | | | | | | | | | Value 4 | +| | 23 | | | | | | | | | Type 5 | +| | 24-25 | | | | | | | | | Value 5 | +| | 26 | | | | | | | | | Type 6 | +| | 27-28 | | | | | | | | | Value 6 | +| | 29 | | | | | | | | | Type 7 | +| | 30-31 | | | | | | | | | Value 7 | +| | 32 | | | | | | | | | Type 8 | +| | 33-34 | | | | | | | | | Value 8 | +| | 35 | | | | | | | | | Type 9 | +| | 36-37 | | | | | | | | | Value 9 | +| | 38 | | | | | | | | | Type 10 | +| | 39-40 | | | | | | | | | Value 10 | +| MIC | | | | | | | | | | Message integrity check | + +NOTE – Test result types are specified in clause 11.2.10. Type-value fields are packed in the lowest byte positions. Unused trailing byte positions may be omitted. If more than 10 type-value pairs are to be returned, an additional test type should be defined in the test message. At the vendor's discretion, a test result may include an ordered sequence of repeated type-value pairs to represent, for example, port ordering, or first/second power input. In this case, missing values can be flagged with type = 255. + +#### A.2.39.3 Format for POTS UNI entity class + +In this format, byte 11 reports a summary MLT result. The result for each test category is limited to the two values *pass test* or *test not run* or *failed test*. Byte 13 reports the results of a dial tone test. + +Byte 12 reports the result of a self-test or a vendor-specific test that returns results in a general purpose buffer. At present, self-test is not supported for the POTS UNI entity class, and this byte should be set to 0. + +There are four possible outcomes for a given test: it can pass, fail, not be run, or not be recognized by the ONU. If an ONU does not support or recognize a given test, it is expected to deny the test request message. To avoid physical damage, an ONU may cease testing if a test fails – usually the hazardous potential test – and thus some subsequent tests will not be run. In addition, the ONU may support some but not all tests of a given suite, such as power measurements in the dial tone test sequence. The category summary in byte 11 includes two values. The value 1 indicates either that all tests in a category passed, or that nothing in the category was tested, while 0 indicates that at least one test in the category failed. Further information appears in flags specific to each test results attribute to indicate whether each detailed test was run or not, whether it passed or failed and whether a measured result is reported or not. + +Several distinct test classes are defined. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This message format pertains to the PPTP POTS UNI entity class. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Message contents | 11 | t | t | x | x | x | x | x | x | tt selects one of the POTS test class formats
0 MLT, dial tone make-break
1 SIP/ITU-T H.248 test call
2..3 Reserved
x Bits reserved for use in specific test classes as defined below | + +###### Test class 0: + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | 0 | 0 | a | b | c | d | e | f | MLT drop test result:
0 fail test a/b/c/d/e/f
1 pass test, or test not run
a hazardous potential
b foreign EMF
c resistive faults
d receiver off-hook
e ringer
f NT1 dc signature test | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | xx: Result of self-test or vendor-specific test
00 failed
01 passed
10 not completed | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 13 | | | b | b | b | d | d | d | Dial tone make-break flags:
ddd – Dial tone draw
000 test not run
01m failed, could not draw
10m slow draw
11m passed
bbb – Dial tone break
000 test not run
01m failed, could not break
10m slow break
11m passed
m – measured value flag
0 measurement not reported
1 measurement reported | +| | 14 | | | a | a | a | b | b | b | Dial tone power flags (Note)
aaa – Quiet channel power
bbb – Dial tone power | +| | 15 | | | a | a | a | b | b | b | Loop test DC voltage flags (Note)
aaa – VDC, tip-ground
bbb – VDC, ring-ground | +| | 16 | | | a | a | a | b | b | b | Loop test AC voltage flags (Note)
aaa – VAC, tip-ground
bbb – VAC, ring-ground | +| | 17 | | | a | a | a | b | b | b | Loop test resistance flags 1 (Note)
aaa – Resistance, tip-ground
bbb – Resistance, ring-ground | +| | 18 | | | a | a | a | b | b | b | Loop test resistance flags 2 (Note)
aaa – Resistance, tip-ring
bbb – Ringer load test | +| | 19 | | | | | | | | | Time to draw dial tone, in 0.1 s units.
Valid only if byte 13 ddd = xx1. | +| | 20 | | | | | | | | | Time to break dial tone, in 0.1 s units.
Valid only if byte 13 bbb = xx1. | +| | 21 | | | | | | | | | Total dial tone power measurement, unsigned absolute value, 0.1 dB resolution, range 0 to [–] 25.5 dBm0. Values above 0 dBm0 are reported as 0. Valid only if byte 14 bbb = xx1. | +| | 22 | | | | | | | | | Quiet channel power measurement, unsigned absolute value, 1 dB resolution, range 0 to [–]90 dBm0. Valid only if byte 14 aaa = xx1. | +| | 23-24 | | | | | | | | | Tip-ground DC voltage, 2s complement, resolution 1 V. Valid only if byte 15 aaa = xx1. | +| | 25-26 | | | | | | | | | Ring-ground DC voltage, 2s complement, resolution 1 V. Valid only if byte 15 bbb = xx1. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 27 | | | | | | | | | Tip-ground AC voltage, $V_{rms}$ . Valid only if byte 16 aaa = xx1. | +| | 28 | | | | | | | | | Ring-ground AC voltage, $V_{rms}$ . Valid only if byte 16 bbb = xx1. | +| | 29-30 | | | | | | | | | Tip-ground DC resistance, kilohms. Infinite resistance: 0xFFFF. Valid only if byte 17 aaa = xx1. | +| | 31-32 | | | | | | | | | Ring-ground DC resistance, kilohms. Infinite resistance: 0xFFFF. Valid only if byte 17 bbb = xx1. | +| | 33-34 | | | | | | | | | Tip-ring DC resistance, kilohms. Infinite resistance: 0xFFFF. Valid only if byte 18 aaa = xx1. | +| | 35 | | | | | | | | | Ringer equivalence, in 0.1 REN units. Valid only if byte 18 bbb = xx1. | +| | 36-37 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer. | +| | 38 | | | a | a | a | b | b | b | Loop tip-ring test AC/DC voltage flags. Bytes 38-41 are optional as a group. The ONU may include or omit them as a group. The OLT should accept either option in accordance with clause 11.2.5.
aaa – VAC, tip-ring
bbb – VDC, tip-ring
(Note) | +| | 39 | | | | | | | | | Tip-ring AC voltage, $V_{rms}$ . Valid only if byte 38 aaa = xx1. | +| | 40-41 | | | | | | | | | Tip-ring DC voltage, 2s complement, resolution 1 V. Valid only if byte 38 bbb = xx1. | +| MIC | | | | | | | | | | Message integrity check | +| NOTE – Coding for 3 bit flag sets is as follows:
000 test not run
010 fail, measurement not reported
011 fail, measurement reported
110 pass, measurement not reported
111 pass, measurement reported. | | | | | | | | | | | + +###### **Test class 1:** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents (Note) | 11 | 0 | 0 | 0 | 1 | x | y | y | y | yyy report the results of the test
000 Test failed
001 Test passed
010 Not completed, line off hook
011 Not completed, other reason
100 Reserved
101 Reserved
110 Reserved
111 Reserved
x Reserved | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +NOTE – Test class 1 tt bits and x reserved bits do not align with clause A.2.39.3 description for tt and x reserved bits. For backwards compatibility reasons, ITU-T G.988 tt bits and reserved bits will continue to be represented as described in this clause. Interoperable implementations should be ready to code test class 1 bits as described in this table. + +##### **A.2.39.4 Format for test action invoked against IP host config data and IPv6 host config data entity classes** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This format applies to entity classes IP host config data and IPv6 host config data. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | x | x | x | xxx: Test result
000 Timed out, no response
001 ICMP echo responses attached
010 ICMP time exceeded responses attached
011 Unexpected ICMP response
100 Target address in large string ME could not be resolved
101..111 Reserved | +| | 12..n | | | | | | | | | See following descriptions for the contents of these bytes | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +If xxx = 001 (echo response – ping), the remainder of the message contains the following content. If the test message specifies the number of times to ping, the ONU should generate that number of echo requests; otherwise the number of echo requests generated is the ONU vendor's default. The resolution of the delay measurement is vendor-specific. The special value 0xFFFF indicates a lost response. + +| | | | | | | | | | | | +|-------|--|--|--|--|--|--|--|--|--|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 12-27 | | | | | | | | | | In the extended ping test, these bytes contain the actual IP address that was pinged 4 bytes for IPv4, 16 bytes for IPv6. If the network address was not resolvable, the ONU should set these bytes to all zeroes.
In the normal (non-extended ping test), delay measurements begin immediately in byte 12, according to the same pattern shown in bytes 28-29, etc. | +| 28-29 | | | | | | | | | | 16 bit measurement of response delay n , expressed in milliseconds. | +| 30-31 | | | | | | | | | | 16 bit measurement of response delay n + 1, expressed in milliseconds. | +| ... | | | | | | | | | | Etc. | + +If xxx = 010 (time exceeded – traceroute), the remainder of the message contains the following content. In PON applications, it is not expected that a route trace will exceed the available space in the message, but if it does, the more distant responses should be dropped. + +| | | | | | | | | | | | +|-----|--|--|--|--|--|--|--|--|--|---------------------------------------------------------------------------| +| | | | | | | | | | | IP address of nearest neighbour (4 bytes, IPv4, or 16 bytes, IPv6) | +| | | | | | | | | | | IP address of second nearest neighbour (4 bytes, IPv4, or 16 bytes, IPv6) | +| ... | | | | | | | | | | Etc. | + +If xxx = 011 (unexpected ICMP response), the remainder of the message contains the following content: + +| | | | | | | | | | | | +|--------------|--|--|--|--|--|--|--|--|--|--------------------------------------------------------------------------------------------------| +| 12 | | | | | | | | | | Type | +| 13 | | | | | | | | | | Code | +| 14-15 | | | | | | | | | | Checksum | +| 16-19 | | | | | | | | | | Bytes 5-8 of ICMP message (meaning depends on type/code) | +| 20- n | | | | | | | | | | Internet header + original datagram (truncated if necessary by extended OMCI message size limit) | + +#### **A.2.39.5 Format for optical line supervision test action invoked against ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier or RE downstream amplifier entity class** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------------------------------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class
NOTE – This message format pertains to ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier or RE downstream amplifier entity classes | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | Type = 1, Power feed voltage | +| | 12-13 | | | | | | | | | Volts, 2s complement, 20 mV resolution | +| | 14 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | Type = 3, Received optical power | +| | 15-16 | | | | | | | | | Decibel-microwatts, 2s complement, 0.002 dB resolution (Coding –32768 to +32767, where 0x00 = 0dBuW, 0x03e8 = +2dBuW, etc.) | +| | 17 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | Type = 5, Mean optical launch power | +| | 18-19 | | | | | | | | | Decibel-microwatts, 2s complement, 0.002 dB resolution (Coding –32768 to +32767, where 0x00 = 0dBuW, 0x03e8 = +2dBuW, etc.) | +| | 20 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | Type = 9, Laser bias current | +| | 21-22 | | | | | | | | | Unsigned integer, 2 µA resolution | +| | 23 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | Type 12, temperature, degrees Celsius | +| | 24-25 | | | | | | | | | 2s complement, 1/256 °C resolution | +| | 26-27 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer.
This field is optional. The OLT may include this field, or in case it is not used, omit it or set it to zero. The OLT should accept either option. | +| MIC | | | | | | | | | | Message integrity check | +| NOTE – Unsupported tests are indicated with test type indicator 0 and 2 bytes of 0 data. | | | | | | | | | | | + +#### A.2.39.6 Format for test action invoked against dot1ag MEP entity class, loopback test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to ONU-G and circuit pack entity classes. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 9 bytes | +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = 1: indicates failure to receive any loopback replies (LBRs) within 5 s | +| | 12-13 | | | | | | | | | Valid LBRs count: the number of valid, in-order LBRs received. | +| | 14-15 | | | | | | | | | Out-of-order LBRs count: the number of valid LBRs received that were out of order. | +| | 16-17 | | | | | | | | | Mismatch LBRs count: the number of received LBRs whose MAC SDU did not match that of the corresponding LBM (except for opcode). Optional feature, set to 0xFF if not supported. | +| | 18-19 | | | | | | | | | Delay from LB message transmission to LB response reception, measured in microseconds. The value 0 indicates no information available. | +| MIC | 20-23 | | | | | | | | | Message integrity check | + +#### A.2.39.7 Format for test action invoked against dot1ag MEP entity class, linktrace test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to ONU-G and circuit pack entity classes. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 13 bytes | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = 1: indicates failure to receive any linktrace replies (LTRs) within 5 s | +| | 12-15 | | | | | | | | | Transaction ID of transmitted LTM | +| | 16-23 | | | | | | | | | Content of egress TLV data field in transmitted LTM (clause 21.8.8 of [IEEE 802.1ag]). The LTRs themselves are captured in the general purpose buffer designated by the test command. | +| MIC | 24-27 | | | | | | | | | Message integrity check | + +#### A.2.40 Get current data + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get current data | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 2 bytes | +| Message contents | 11-12 | | | | | | | | | Attribute mask | +| MIC | 13-16 | | | | | | | | | Message integrity check | + +#### A.2.41 Get current data response + +Bytes 14..17 are always reserved for the optional-attribute and attribute execution masks; however, the contents of these bytes are only valid in conjunction with the 1001 encoding used to indicate failed or unknown attributes. If the result code is not 1001, these bytes should be set to 0 by the ONU and ignored by the OLT. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get current data | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| | 12-13 | | | | | | | | | Attribute mask | +| | 14-15 | | | | | | | | | Optional-attribute mask, used with 1001 encoding:
0 default
1 unsupported attribute | +| | 16-17 | | | | | | | | | Attribute execution mask, used with 1001 encoding:
0 default
1 failed attribute | +| | 18-n | | | | | | | | | Value of first attribute included (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of last attribute included | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +#### A.2.42 Set table + +The set table command provides a way in which a number of rows may be written into a table with a single command. The same function can be achieved with individual set commands, with each command instance directed to a single row of the table. + +Writeable tables in the OMCI have various mechanisms to control whether a given set operation causes a new row to be added to the table, an existing row to be overwritten or deleted, or the entire table cleared. All such mechanisms are embedded within the definition of the table row itself. Conflicting control semantics are therefore possible. The set table command executes each table row sequentially, in list order. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = set table | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field, bytes | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------| +| Message contents | 11-12 | | | | | | | | | Attribute mask (Note) | +| | 13-n | | | | | | | | | Value of the first table row (size depending on table definition) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of the last table row | +| MIC | | | | | | | | | | Message integrity check, 4 bytes | + +NOTE – Exactly one bit of the attribute mask must be set, and that bit must correspond to a read-write table attribute in the definition of the parent managed entity. + +#### A.2.43 Set table response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = set table | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | Extended OMCI = 0x0B | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents length | 9-10 | | | | | | | | | Size of message contents field = 1 byte | +| Message contents | 11 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| MIC | 12-15 | | | | | | | | | Message integrity check | + +### A.3 Baseline message set + +All G-PON OLTs and ONUs support the baseline message set. + +#### A.3.1 Create + +It should be noted that the message contents for the create message apply only to attributes that are defined to be set-by-create. Writeable attributes that are not set-by-create are not permitted in a create message. Thus, the first byte of the message contents field begins with the attribute value for the first set-by-create attribute and so forth. Space for each set-by-create attribute must be allocated in the create message, even if the attribute is optional. When an optional attribute is not to be instantiated, the placeholder value to be entered into this space is specific to the definition of each attribute. If the ONU does not support a given optional set-by-create attribute, the ONU should simply ignore that field in the create message, and the ONU should not set an illegal value flag in the create message response. + +When the OMCI specifies a default value for a set-by-create attribute, the intention is that the OLT populate the default recommendation into the create message. The ONU is not responsible for instantiating any particular value for a set-by-create attribute. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = create | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | | | | | | | | | Attribute value of first set-by-create attribute, NOT the ME ID (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last set-by-create attribute (size depending on the type of attribute) | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.2 Create response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = create | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 = command processed successfully
0001 = command processing error
0010 = command not supported
0011 = parameter error
0100 = unknown managed entity
0101 = unknown managed entity instance
0110 = device busy
0111 = instance exists | +| | 10-11 | | | | | | | | | Attribute execution mask, used with 0011 encoding:
0 = attribute ok
1 = illegal value attribute | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|--------------| +| | 12-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.3 Delete + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = delete | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.4 Delete response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = delete | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | | | | | | | | | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.5 Set + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = set | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------| +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9-10 | | | | | | | | | Attribute mask | +| | 11 | | | | | | | | | Attribute value of first attribute to set (size depending on the type of attribute) | +| | | | | | | | | | | | +| | | | | | | | | | | Attribute value of last attribute to set (size depending on the type of attribute) | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.6 Set response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = set | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| | 10-11 | | | | | | | | | Optional attribute mask, used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 12-13 | | | | | | | | | Attribute execution mask, used with 1001 encoding:
0 = default
1 = failed attribute | +| | 14-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.7 Get + +Based on the size of the message contents field, the aggregate size of the attributes requested by a single get command should not exceed 25 bytes. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9-10 | | | | | | | | | Attribute mask | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.8 Get response + +Bytes 37 to 40 are always reserved for the optional attribute and attribute execution masks; however, the contents of these bytes are only valid in conjunction with the 1001 encoding used to indicate failed or unknown attributes. + +When the OLT wishes to transfer an attribute whose size is, or might be larger than the space available in one OMCI message (table attribute), the ONU responds with four bytes to indicate the size of that attribute with an appropriate attribute mask. The OLT should then use the get next message in order to retrieve the attribute. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| | 10-11 | | | | | | | | | Attribute mask | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------| +| | 12 | | | | | | | | | Value of first attribute included (size depending on the type of attribute) | +| | | | | | | | | | | | +| | | | | | | | | | | Value of last attribute included (size depending on the type of attribute) | +| | xx-36 | | | | | | | | | Zero padding | +| | 37-38 | | | | | | | | | Optional attribute mask, used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 39-40 | | | | | | | | | Attribute execution mask, used with 1001 encoding:
0 = default
1 = failed attribute | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.9 Get all alarms + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get all alarms | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = alarm retrieval mode
0 = Get all alarms regardless of ARC status
1 = Get all alarms not currently under ARC | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.10 Get all alarms response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get all alarms | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Number of subsequent get all alarms next commands | +| | 11-40 | | | | | | | | | Zero padding | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|----------| +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.11 Get all alarms next + +Command sequence numbers start from 0 onwards. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get all alarms next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Command sequence number | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.12 Get all alarms next response + +The bit map used in the get all alarms next response for a given ME class is identical to the bit map used in the alarm notifications for that ME class. + +In the case where the ONU receives a get all alarms next request message in which the command sequence number is out of range, the ONU should respond with a message in which bytes 9 to 40 are all set to 0. This corresponds to a response with entity class 0, entity instance 0, and bit map all 0s. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get all alarms next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Entity class whose alarms are reported | +| | 11-12 | | | | | | | | | Entity instance whose alarms are reported | +| | 13-40 | x | x | x | x | x | x | x | x | Bit map alarms | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.13 MIB upload + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB upload | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.14 MIB upload response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB upload | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Number of subsequent MIB upload next commands | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.15 MIB upload next + +Command sequence numbers start from 0 onwards. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB upload next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Command sequence number | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.16 MIB upload next response + +If the ONU receives an MIB upload next request message whose command sequence number is out of range, it should respond with a message in which bytes 9 to 40 are all set to 0. This corresponds to a response with entity class 0, entity instance 0, attribute mask 0, and padding from byte 15 to byte 40. + +Note that if all attributes of a ME do not fit within one MIB upload next response message, the attributes will be split over several messages. The OLT can use the information in the attribute mask to determine which attribute values are reported in which MIB upload next response message. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB upload next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Entity class of object | +| | 11-12 | | | | | | | | | Entity instance of object | +| | 13-14 | | | | | | | | | Attribute mask | +| | 15-n | | | | | | | | | Value of the first attribute (size depending on type of the attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Value of the last attribute (size depending on type of the attribute) | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.17 MIB reset + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = MIB reset | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.18 MIB reset response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = MIB reset | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU data | +| | 7-8 | | | | | | | | | Entity instance = 0 | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.19 Alarm + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = alarm | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9-36 | | | | | | | | | Alarm bit map | +| | 37-39 | | | | | | | | | Zero padding | +| | 40 | | | | | | | | | Alarm sequence number | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.20 Attribute value change + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = attribute value change | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|--------------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------| +| Message contents | 9-10 | | | | | | | | | Attribute mask | +| | 11- n | | | | | | | | | Attribute value of first attribute changed (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last attribute changed (size depending on the type of attribute) | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +NOTE 1 – For table attributes, the AVC message does not contain an attribute value (only a mask), and no snapshot of the table is created. If the OLT wishes to obtain the new value, it must then do a get operation, followed by the required number of get next operations. + +NOTE 2 – If there is insufficient space in the message body for the new values of all changed (non-table) attributes, the ONU should issue multiple AVCs, each with a consistent attribute mask and a list of new attribute values, the total to include all changed attributes and their new values. + +### A.3.21 Test + +The format of the test message is specific to the target entity class. A number of formats are presently defined. Future test extensions for a given entity class can be supported by adding additional encodings to presently unused bits or bytes. Future specification of tests for other entity classes may use an existing format or may define new formats for the test message. These extension mechanisms allow future tests to be supported without changing the principle of operation. + +**A.3.21.1 Format for ONU-G, ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier, RE downstream amplifier and circuit pack entity classes** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to entity classes ONU-G, ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier, RE downstream amplifier and circuit pack. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | xxxx = select test
0000..0110 reserved for future use
0111 self-test
1000..1111 vendor-specific use
See the description related to the test result message. | +| | 10-11 | | | | | | | | | Pointer to a general purpose buffer ME, used to return vendor-specific test results.
0 = unused (vendor-specific results are not expected). | +| | 12-13 | | | | | | | | | Pointer to an octet string ME, used to define the vendor-specific test parameters.
0 = unused (vendor-specific parameters are not specified). | +| | 14-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +**A.3.21.2 Format for IP host config data and IPv6 host config entity classes** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to entity classes IP host config data and IPv6 host config data. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|--------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | xxxx = select test
0001 = Ping
0010 = Traceroute
0011 = Extended ping
0100..0111 Reserved
1000..1111 Vendor-specific use
The ICMP message is intended to be from the ONU upstream towards the network. See discussion related to the test result message. | +| | 10-13 | | | | | | | | | Option 1: IPv4 address of target (zero if byte 0 specifies extended ping test) | +| | 10-25 | | | | | | | | | Option 2: IPv6 address of target (zero if byte 0 specifies extended ping test) | +| | 26 | | | | | | | | | Number of times to ping.
This field pertains to both explicit and extended ping tests. The value 0 selects the ONU's internal default.
NOTE – The number is bounded by the size of the test result message. It can be up to 15 for explicit ping and up to 7 for extended ping. | +| | 27-28 | | | | | | | | | Pointer to large string ME that identifies the target via a DNS-parsable string. This field is used only for the extended ping test. | +| | ...-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.21.3 Format for PTP POTS UNI entity class + +The test message for POTS UNIs supports two basic categories of test operation, a defined set of tests that look in and out from the POTS port, and a set of code points that may be used for vendor-specific tests. The latter category is further subdivided into code points that return test results in a general purpose buffer ME, using the test results message primarily as an event trigger to signal test completion, and code points that return all test results in an ordinary test result message. If it is needed, the OLT must create the general purpose buffer ME before initiating the test action. + +Note that a single message can be used to initiate multiple tests on a given ME if desired. + +Bytes 10-23 are used by the dial tone make-break test. A zero value for a timer causes the ONU to use its built-in defaults. As many as three dial tone frequencies can be specified, or omitted by setting their values to 0. Other fields are also omitted with the value 0, or controlled by flags. An ONU can support the dial tone test with internal defaults only, and it is not required to support any of the attributes of bytes 10-23. Likewise, an ONU can use internal defaults for a drop test, rather than the + +values given in bytes 24-33. The capabilities of an ONU are documented by the vendor and known through administrative practices. + +Several distinct test classes are defined. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
Bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to entity class PPTP POTS UNI. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | x | 0 | t | t | x | x | x | x | tt selects one of the POTS test class formats
0 MLT, dial tone make-break
1 SIP/ITU-T H.248 test call
2..3 Reserved
x Bits reserved for use in specific test classes as defined below | + +Test class 0: + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 9 | a | 0 | 0 | 0 | x | x | x | x | a – test mode
0 = normal; deny test if line busy
1 = forced mode
xxxx = select test
0000 = all MLTs
0001 = hazardous potential
0010 = foreign EMF
0011 = resistive faults
0100 = receiver off-hook
0101 = ringer
0110 = NT1 dc signature test
0111 = self-test
1000 = dial tone make-break test
1001..1011 = vendor-specific test, all results returned in test results message
1100..1111 is a vendor-specific test, test results returned in general purpose buffer ME. The ONU should deny a test operation command in this range if bytes 34-35 do not point to a GP buffer. | +| | 10 | | | | | | | | | DBDT timer T1 (slow dial tone threshold), in units of 0.1 s. Range 0.1 to 6.0 s. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|-------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------| +| | 11 | | | | | | | | | DBDT timer T2 (no dial tone threshold), in units of 0.1 s. Range 1.0 to 10.0 s. | +| | 12 | | | | | | | | | DBDT timer T3 (slow break dial tone threshold), in units of 0.1 s. Range 0.1 to 3.0 s. | +| | 13 | | | | | | | | | DBDT timer T4 (no break dial tone threshold), in units of 0.1 s. Range 1.0 to 3.0 s. | +| | 14 | | | | | | | d | p | DBDT control byte
d: dialled digit
1 = dialled digit specified in byte 15
0 = use default digit
p = pulse (1) or tone (0) dialling | +| | 15 | | | | | | | | | Digit to be dialled, ASCII character in range "0"-"9", "*", "#". | +| | 16-17 | | | | | | | | | Dial tone frequency 1, in hertz | +| | 18-19 | | | | | | | | | Dial tone frequency 2, in hertz. 0 = unused (i.e., if only one tone is specified). | +| | 20-21 | | | | | | | | | Dial tone frequency 3, in hertz. 0 = unused (i.e., if only one or two tones are specified). | +| | 22 | | | | | | | | | Dial tone power threshold, absolute value, 0.1 dB resolution, range [-]0.1 to [-]25.3 dBm0, e.g., -13 dBm0 = 0x82. 0x00 = unspecified. | +| | 23 | | | | | | | | | Idle channel power threshold, absolute value, 1 dB resolution, range [-]1 to [-]90 dBm0. 0x00 = unspecified. | +| | 24 | | | | | | | | | DC hazardous voltage threshold, absolute value, volts 0x00 = unspecified. | +| | 25 | | | | | | | | | AC hazardous voltage threshold, volts RMS 0x00 = unspecified | +| | 26 | | | | | | | | | DC foreign voltage threshold, absolute value, volts 0x00 = unspecified | +| | 27 | | | | | | | | | AC foreign voltage threshold, volts RMS 0x00 = unspecified | +| | 28 | | | | | | | | | Tip-ground and ring-ground resistance threshold, kilohms 0x00 = unspecified | +| | 29 | | | | | | | | | Tip-ring resistance threshold, kilohms 0x00 = unspecified | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------------------------------------------------| +| | 30-31 | | | | | | | | | Ringer equivalence minimum threshold, in 0.01 REN units 0x00 = unspecified | +| | 32-33 | | | | | | | | | Ringer equivalence maximum threshold, in 0.01 REN units 0x00 = unspecified. | +| | 34-35 | | | | | | | | | Pointer to a general purpose buffer ME, used to return vendor-specific test results | +| | 36-37 | | | | | | | | | Pointer to an octet string ME, used to define vendor-specific test parameters.
0 = unused (vendor-specific parameters are not specified). | +| | 38-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +Test class 1: + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------| +| Message contents | 9 | a | 0 | 0 | 1 | x | x | x | x | a – test mode
0 normal; deny test if line busy
1 forced mode
x Reserved | +| | 10-25 | | | | | | | | | ASCII string containing the number to be dialled. Trailing unused octets are padded with null bytes. | +| | 26-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +#### A.3.21.4 Format for dot1ag MEP entity class, loopback test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to the dot1ag MEP entity class. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = select test
0: Ethernet loopback test
1: IEEE 802.1ag linktrace test (see separate format description below)
Other values are reserved. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 10 | 0 | 0 | 0 | c | p | p | p | d | If c = 1, the value of the MEP's CCM and LTM priority attribute is used, with drop eligibility false.
If c = 0, pppd represents the priority (P bits) and drop eligibility fields of the transmitted LBM frame. | +| | 11-16 | | | | | | | | | MAC address of target MHF or MEP, or 0 if the destination MEP ID is to be used instead. [IEEE 802.1ag] specifies unicast addresses; [ITU-T Y.1731] also allows for multicast. | +| | 17-18 | | | | | | | | | Destination MEP ID, in the range 1..8191, or 0 if the MAC address in bytes 11-16 is to be used instead. | +| | 19-20 | | | | | | | | | Repetition count, range 1..1024. This governs how many LBMs are generated. The rate at which LBMs are generated is not specified. If 5 s elapse with no LBRs received, the test aborts. | +| | 21-22 | | | | | | | | | These four fields are pointers to as many as four octet string MEs, which are concatenated to form an octet string of up to 1500 bytes. The string is packaged into a data TLV and transmitted as part of the LBM. If all four fields are null pointers, no data TLV is sent. If only one octet string is needed, it should be specified in bytes 21-22, etc., with null pointers in the higher-numbered bytes of the test message. | +| | 23-24 | | | | | | | | | | +| | 25-26 | | | | | | | | | | +| | 27-28 | | | | | | | | | | +| | 29-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +#### A.3.21.5 Format for dot1ag MEP entity class, linktrace test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = test | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to the dot1ag MEP entity class. | +| | 7-8 | | | | | | | | | Entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = select test
0: Ethernet loopback test (see separate format description above)
1: IEEE 802.1ag linktrace test
Other values reserved. | +| | 10 | f | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Flags, a bit map
f: Use FDB only . When 1, the bridge uses only its normal MAC forwarding tables for forwarding. When 0, the bridge may also consult its MIP CCM database to determine the forwarding port. | +| | 11-16 | | | | | | | | | Unicast MAC address of target MHF or MEP, or 0 if the destination MEP ID is to be used instead. | +| | 17-18 | | | | | | | | | Destination MEP ID, in the range 1..8191, or 0 if the unicast MAC address in bytes 11-16 is to be used instead. | +| | 19 | | | | | | | | | Max hops count – specifies initial TTL; limits the number of relay stages through which the LTM is forwarded before being discarded, and the number of LTRs that may be returned. [IEEE 802.1ag] recommends a default value of 64. | +| | 20-21 | | | | | | | | | Pointer to a general purpose buffer ME, used to return the linktrace results. The ONU should deny the test operation command if this field is a null or an invalid pointer. | +| | 22-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.22 Test response + +If an ONU does not support all tests requested in byte 9 of the test message, it should not execute any test and should respond with result 0010, command not supported. If an ONU supports all of the requested tests but cannot support one or more of the explicitly specified threshold attributes, it should not execute any test and should respond with result 0011, parameter error. The test command could then be reissued with different thresholds or default thresholds, and would be expected to succeed. + +The test response message is an indication to the OLT that the test request is received and is being processed. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = test | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-40 | | | | | | | | | Zero padding | +| | 41-48 | | | | | | | | | | + +### A.3.23 Start software download + +When a file is to be downloaded to a single instance of the software image ME, the ME ID is specified in bytes 7-8. An optional feature permits the same file to be downloaded to a number of circuit packs by setting bytes 7-8 = 0xFFFF and specifying the software image ME IDs in bytes 15..16, etc. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = start software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| ME identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------| +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents | 9 | | | | | | | | | Window size – 1 | +| | 10-13 | | | | | | | | | Image size in bytes | +| | 14 | | | | | | | | | Number of circuit packs to be updated in parallel (value 1..9) | +| | 15 | | | | | | | | | MS byte of software image instance (slot number of circuit pack) | +| | 16 | | | | | | | | | LS byte of software image instance (value 0..1 or 2..254 vendor-specific) | +| | 17-n | | | | | | | | | Software image ME IDs (same format as bytes 15..16) for additional simultaneous downloads | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.24 Start software download response + +When a file is downloaded to a single software image ME, the response contains the target ME ID in bytes 7-8, a result code in byte 9, a window size counterproposal (which may be the same as that suggested by the OLT in the original request) in byte 10, and 0 padding for the remaining bytes. + +An ONU that supports the optional parallel download feature responds with the full format shown below. If the ONU does not support the parallel download feature, it responds with the code 0b0101, unknown ME instance. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|--------------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = start software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10 | | | | | | | | | Window size – 1 | +| | 11 | | | | | | | | | Number of instances responding (value 0..9) | +| | 12-13 | | | | | | | | | ME ID of software image entity instance (slot number plus instance 0..1 or 2..254 vendor-specific) | +| | 14 | | | | | | | | | Result, reason for bytes 12..13 – same coding as byte 9 | +| | 15- n | | | | | | | | | Repeat coding of bytes 12..14 for additional requested software image instances | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.25 Download section + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|----------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message type | 3 | 0 | x | 0 | | | | | | DB = 0, AR = x, AK = 0
x = 0: no response expected
(section within the window)
x = 1: response expected (last
section of a window)
bits 5-1: action = sw download
section | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity
identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple
software image managed
entities | +| | 8 | | | | | | | | | LS byte of software image instance
00 instance 0
01 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents | 9 | | | | | | | | | Download section number | +| | 10-40 | | | | | | | | | Data; 0 padding if final transfer
requires only a partial block | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.26 Download section response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------| +| Transaction
correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = sw download
section | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity
identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple
software image managed
entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10 | | | | | | | | | Download section number | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.27 End software download + +The format of this command is similar to that of the start software download message. Bytes 17..N support the optional parallel download feature, and are set to 0 for download to a single target. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = end software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents | 9-12 | | | | | | | | | CRC-32, computed over all bytes of the software image (excluding padding), as specified in [ITU-T I.363.5]. | +| | 13-16 | | | | | | | | | Image size in bytes | +| | 17 | | | | | | | | | Number of parallel download instances sent in this message (value 1..9) | +| | 18 | | | | | | | | | MS byte of software image instance (slot number of circuit pack) | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------| +| | 19 | | | | | | | | | LS byte of software image instance (value 0..1 or 2..254 vendor-specific) | +| | 20-n | | | | | | | | | Software image ME IDs (same format as bytes 18..19) for additional simultaneous downloads | +| | xx-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.28 End software download response + +The response message informs the OLT whether the download command was successful. If a single software image ME was targeted for download, byte 9 reports the result of the process. Byte 9 reports device busy as long as any of the instances is busy writing the image to a non-volatile store. Once the ONU has stored all images successfully, it responds with a 0 in byte 9 and a separate result for each software image ME. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = end software download | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte of software image instance
0 ONU-G
1..254 slot number
255 download to multiple software image managed entities | +| | 8 | | | | | | | | | LS byte of software image instance
0 instance 0
1 instance 1
2..254 vendor-specific use
255 multiple download | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully (CRC correct)
0001 command processing error (CRC incorrect)
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10 | | | | | | | | | Number of instances responding (value 0..9) | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------| +| | 11-12 | | | | | | | | | ME ID of software image entity instance (slot number plus instance 0..1 or 2..254 vendor-specific) | +| | 13 | | | | | | | | | Result, reason for bytes 11..12 – same coding as byte 9 | +| | 14-37 | | | | | | | | | Repeat coding of bytes 11..13 for additional software image instances | +| | 38-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.29 Activate image + +Because the end software download only signals completion after a new image has been stored in non-volatile memory, it is possible for the OLT to send the activate image command immediately after a successful end software download response. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = activate image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | F | F | Bits FF:
00 Activate image unconditionally
01 Activate image only if no POTS/VoIP calls are in progress
10 Activate image only if no emergency call is in progress (Note)
11 Reserved
If the ONU denies the Activate image command because of the FF field, it returns result, reason code 0110, device busy. | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|---|---|---|---|---|---|---|---|----------| +| NOTE – The ONU determines the presence of an originating emergency call on the basis of the Emergency service number attribute of the VoIP feature access codes ME. Other ways for the ONU to determine the presence of an emergency call are for further study. | | | | | | | | | | | + +### A.3.30 Activate image response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = activate image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.31 Commit image + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = commit image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents | 9-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.32 Commit image response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = commit image | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = software image | +| | 7 | | | | | | | | | MS byte entity instance
0 ONU-G
1..254 slot number | +| | 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | LS byte entity instance
0 first instance
1 second instance
2..254 vendor-specific use | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.33 Synchronize time + +The synchronize time command controls the tick boundary for PM collection, and optionally, a date and time clock. + +If this message specifies the time (and optionally the date), the ONU sets its PM interval counter to a current offset from the most recent 15 min boundary, i.e., to a value in the range 0..899 s. This may cause the current PM collection interval to be longer or shorter than 900 s. Date and time are not explicitly required in an ONU, but if the ONU has a real-time clock, it is also set by this message. If the OLT does not wish to specify a date, it may set year, month and day fields to 0.If the ONU does not support the setting of the date, it will use the success result info field in the synchronize time response message to indicate that only the 15 min tick boundary was set. + +If date and time are not present in the message, the ONU sets its PM interval counter to 0. This may cause the current PM collection interval to be shorter than 900 s. The effect on a possible ONU real-time clock is not specified. + +There is no intention that this message be used to establish a precise time of day reference. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = synchronize time | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class = ONU-G | +| | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9-10 | | | | | | | | | Year, e.g., 2009 | +| | 11 | | | | | | | | | Month, range 1..12 | +| | 12 | | | | | | | | | Day of month, range 1..31 | +| | 13 | | | | | | | | | Hour of day, range 0..23 | +| | 14 | | | | | | | | | Minute of hour, range 0..59 | +| | 15 | | | | | | | | | Second of minute, range 0..59 | +| | 16-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.34 Synchronize time response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
Bits 5-1: action = synchronize time | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| | 5-6 | | | | | | | | | Entity class = ONU-G | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity identifier | 7-8 | | | | | | | | | Entity instance = 0 | +| Message contents | 9 | | | | | | | | | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10 | | | | | | | | | Success result info – this field has a meaning only when the result, reason code in byte 9 was "0000 command processed successfully".
0000 15 min tick boundary set successfully
0001 Date and 15 min tick boundary set successfully | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.35 Reboot + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = reboot | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | F | F | Bits FF:
00 Reboot unconditionally
01 Reboot only if no POTS/VoIP calls are in progress
10 Reboot only if no emergency call is in progress (Note)
11 Reserved
If the ONU denies the reboot command because of the FF field, it returns result, reason code 0110, device busy. | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +NOTE – The ONU determines the presence of an originating emergency call on the basis of the Emergency service number attribute of the VoIP feature access codes ME. Other ways for the ONU to determine the presence of an emergency call are for further study. + +### A.3.36 Reboot response + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = reboot | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | | | | | | | | | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.37 Get next + +Command sequence numbers start from 0 onwards. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9-10 | | | | | | | | | Attribute mask | +| | 11-12 | | | | | | | | | Command sequence number | +| | 13-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.38 Get next response + +If the ONU receives a get next request message whose command sequence number is out of range, the ONU responds with parameter error. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|----------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get next | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy | +| | 10-11 | | | | | | | | | Attribute mask | +| | 12-n | | | | | | | | | Attribute value (size depending on the type of attribute) | +| | xx-40 | | | | | | | | | Zero padding | +| | 41-48 | | | | | | | | | OMCI trailer | + +### A.3.39 Test result + +The test result message reports the outcome of a test. In the case of a requested test, the transaction correlation identifier of the test result message is identical to the transaction correlation identifier of the test message that initiated the corresponding test. In the case of a self-triggered test result, the transaction correlation identifier is set to 0. + +Several formats are currently defined. They are used as follows: + +- self-test results, ONU-G, circuit pack, or any other ME that supports self-test; +- vendor-specific test results, generic format, any ME that supports it; +- POTS test results, either MLT, dial tone draw-break or vendor-specific POTS tests that use a general purpose buffer; +- ICMP tests, either ping or traceroute; +- the results of an optical line supervision test on the ANI-G, RE ANI-G, PTP RE UNI, RE upstream amplifier or RE downstream amplifier; +- [IEEE 802.1ag] loopback and linktrace tests. + +If a new test for the currently supported entities is defined in the future, the corresponding test results can be reported by extending the test result message layout. If a new test for other ME classes is defined in the future, a new test result message layout may be defined. + +#### A.3.39.1 Format for self-test action invoked against ONU-G and circuit pack entity classes + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|----------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------| +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to ONU-G and circuit pack entity classes. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Unused | +| | 10 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | Self-test result:
xx = 00: failed
xx = 01: passed
xx = 10: not completed | +| | 11-12 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer, otherwise zero. | +| | 13-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.39.2 Format for vendor-specific test actions invoked against ONU-G and circuit pack entity classes + +This format is also used for vendor-specific test actions invoked against the PPTP POTS UNI entity class when no general purpose buffer is needed. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to ONU-G, circuit pack and PPTP POTS UNI entity classes. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | | | | | | | | | Type 1 (Note) | +| | 10-11 | | | | | | | | | Value 1 | +| | 12 | | | | | | | | | Type 2 | +| | 13-14 | | | | | | | | | Value 2 | +| | 15 | | | | | | | | | Type 3 | +| | 16-17 | | | | | | | | | Value 3 | +| | 18 | | | | | | | | | Type 4 | +| | 19-20 | | | | | | | | | Value 4 | +| | 21 | | | | | | | | | Type 5 | +| | 22-23 | | | | | | | | | Value 5 | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------|---|---|---|---|---|---|---|---|--------------| +| | 24 | | | | | | | | | Type 6 | +| | 25-26 | | | | | | | | | Value 6 | +| | 27 | | | | | | | | | Type 7 | +| | 28-29 | | | | | | | | | Value 7 | +| | 30 | | | | | | | | | Type 8 | +| | 31-32 | | | | | | | | | Value 8 | +| | 33 | | | | | | | | | Type 9 | +| | 34-35 | | | | | | | | | Value 9 | +| | 36 | | | | | | | | | Type 10 | +| | 37-38 | | | | | | | | | Value 10 | +| | 39-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +NOTE – Test result types are specified in clause 11.2.10. Type-value fields are packed in the lowest byte positions. Unused trailing byte positions are filled with 0 values. If more than 10 type-value pairs are to be returned, an additional test type should be defined in the test message. At the vendor's discretion, a test result may include an ordered sequence of repeated type-value pairs to represent, for example, port ordering, or first/second power input. In this case, missing values can be flagged with type = 255. + +### A.3.39.3 Format for PPTP POTS UNI entity class + +Byte 9 reports a summary MLT result. The result for each test category is limited to the two values *test passed or was not executed* or *test failed*. Bytes 11 and 12 report the results of a dial tone test. + +Byte 10 reports the result of a self-test or a vendor-specific test that returns results in a general purpose buffer. At present, self-test is not supported for the PPTP POTS UNI entity class, and this byte should be set to 0. + +There are four possible outcomes for a given test: it can pass, fail, not be run, or not be recognized by the ONU. If an ONU does not support or recognize a given test, it is expected to deny the test request message. To avoid physical damage, an ONU may cease testing if a test – usually hazardous potential – fails, and thus some subsequent tests will not be run. In addition, the ONU may support some but not all tests of a given suite, such as power measurements in the dial tone test sequence. The category summary in byte 9 includes two values. The value 1 indicates either that all tests in a category passed, or that nothing in the category was tested, while 0 indicates that at least one test in the category failed. Further information appears in flags specific to each test result attribute to indicate whether each detailed test was run or not, whether it passed or failed and whether a measured result is reported or not. + +Several distinct test classes are defined. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to PPTP POTS UNI entity class. | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | t | t | x | x | x | x | x | x | tt selects one of the POTS test class formats
0 MLT, dial tone make-break
1 SIP/ITU-T H.248 test call
2..3 Reserved
x Bits reserved for use in specific test classes as defined below | + +Test class 0: + +| | | | | | | | | | | | +|------------------|----|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents | 9 | 0 | 0 | a | b | c | d | e | f | MLT drop test result:
0 = fail test a/b/c/d/e/f
1 = pass test, or test not run
a/b/c/d/e/f:
a = hazardous potential
b = foreign EMF
c = resistive faults
d = receiver off-hook
e = ringer
f = NT 1 dc signature test | +| | 10 | 0 | 0 | 0 | 0 | 0 | 0 | x | x | Result of self-test or vendor-specific test:
xx = 00: failed
xx = 01: passed
xx = 10: not completed | +| | 11 | | | b | b | b | d | d | d | Dial tone make-break flags:
Ddd – Dial tone draw
= 000 test not run
= 01 m failed, could not draw
= 10 m slow draw
= 11 m passed
bbb – Dial tone break
= 000 test not run
= 01 m failed, could not break
= 10 m slow break
= 11 m passed
m – measured value flag
= 0 measurement not reported
= 1 measurement reported | +| | 12 | | | a | a | a | b | b | b | Dial tone power flags:
aaa – quiet channel power
bbb – dial tone power
(Note) | +| | 13 | | | a | a | a | b | b | b | Loop test DC voltage flags
aaa – VDC, tip-ground
bbb – VDC, ring-ground
(Note) | + +| | | | | | | | | | | +|-------|--|--|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 14 | | | a | a | a | b | b | b | Loop test AC voltage flags
aaa – VAC, tip-ground
bbb – VAC, ring-ground
(Note) | +| 15 | | | a | a | a | b | b | b | Loop test resistance flags 1
aaa – resistance, tip-ground
bbb – resistance, ring-ground
(Note) | +| 16 | | | a | a | a | b | b | b | Loop test resistance flags 2
aaa – resistance, tip-ring
bbb – ringer load test
(Note) | +| 17 | | | | | | | | | Time to draw dial tone, in 0.1 s units. Valid only if byte 11 ddd = xx1. | +| 18 | | | | | | | | | Time to break dial tone, in 0.1 s units. Valid only if byte 11 bbb = xx1. | +| 19 | | | | | | | | | Total dial tone power measurement, unsigned absolute value, 0.1 dB resolution, range 0 to [–]25.5 dBm0. Values above 0 dBm0 are reported as 0. Valid only if byte 12 bbb = xx1. | +| 20 | | | | | | | | | Quiet channel power measurement, unsigned absolute value, 1 dB resolution, range 0 to [–]90 dBm0. Valid only if byte 12 aaa = xx1. | +| 21-22 | | | | | | | | | Tip-ground DC voltage, 2s complement, resolution 1 V. Valid only if byte 13 aaa = xx1. | +| 23-24 | | | | | | | | | Ring-ground DC voltage, 2s complement, resolution 1 V. Valid only if byte 13 bbb = xx1. | +| 25 | | | | | | | | | Tip-ground AC voltage, Vrms. Valid only if byte 14 aaa = xx1. | +| 26 | | | | | | | | | Ring-ground AC voltage, Vrms. Valid only if byte 14 bbb = xx1. | +| 27-28 | | | | | | | | | Tip-ground DC resistance, kilohms. Infinite resistance: 0xFFFF. Valid only if byte 15 aaa = xx1. | +| 29-30 | | | | | | | | | Ring-ground DC resistance, kilohms. Infinite resistance: 0xFFFF. Valid only if byte 15 bbb = xx1. | +| 31-32 | | | | | | | | | Tip-ring DC resistance, kilohms. Infinite resistance: 0xFFFF. Valid only if byte 16 aaa = xx1. | + +| | | | | | | | | | | | +|--------------|-------|--|--|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------| +| | 33 | | | | | | | | | Ringer equivalence, in 0.1 REN units. Valid only if byte 16 bbb = xx1. | +| | 34-35 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer. | +| | 36 | | | a | a | a | b | b | b | Loop tip-ring test AC/DC voltage flags
aaa – VAC, tip-ring
bbb – VDC, tip-ring
(Note) | +| | 37 | | | | | | | | | Tip-ring AC voltage, Vrms. Valid only if byte 36 aaa = xx1. | +| | 38-39 | | | | | | | | | Tip-ring DC voltage, 2s complement, resolution 1 V. Valid only if byte 36 bbb = xx1. | +| | 40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +NOTE – Coding for 3 bit flag sets is as follows: += 000 test not run += 010 fail, measurement not reported += 011 fail, measurement reported += 110 pass, measurement not reported += 111 pass, measurement reported. + +Test class 1: + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|----------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Message contents
(Note) | 9 | 0 | 0 | 0 | 1 | x | y | y | y | yyy report the results of the test
000 Test failed
001 Test passed
010 Not completed, line off hook
011 Not completed, other reason
100 Reserved
101 Reserved
110 Reserved
111 Reserved
x Reserved | +| | 10-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +NOTE – The test class 1 tt bits and x reserved bits do not align with clause A.3.39.3 description for tt and x reserved bits. For backwards compatibility reasons, ITU-T G.988 tt bits and reserved bits will continue to be represented as described in this table. Interoperable implementations should be ready to code test class 1 bits as described in this clause. + +**A.3.39.4 Format for test action invoked against IP host config data and IPv6 host config data entity classes** + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This format applies to entity classes IP host config data and IPv6 host config data. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | x | x | x | Test result:
xxx = 000: timed out, no response
xxx = 001: ICMP echo responses attached
xxx = 010: ICMP time exceeded responses attached
xxx = 011: Unexpected ICMP response
xxx = 100: target address in large string ME could not be resolved
xxx = 101-111: Reserved | +| | 10 | 0 | 0 | 0 | y | y | y | y | y | yyyyy: number of meaningful bytes in the remainder of the test result message. In the case of extended ping, this field is the number of bytes that contain delay measurement values. | + +If xxx = 001 (echo response – ping), the remainder of the message contains the following content. If the test message specifies the number of times to ping, the ONU should generate that number of echo requests; otherwise the number of echo requests generated is the ONU vendor's default. The resolution of the delay measurement is vendor-specific. The special value 0xFFFF indicates a lost response. + +| | | | | | | | | | | | +|--|-------|--|--|--|--|--|--|--|--|-------------------------------------------------------------------| +| | 11-12 | | | | | | | | | 16 bit measurement of response delay 1, expressed in milliseconds | +| | 13-14 | | | | | | | | | 16 bit measurement of response delay 2, expressed in milliseconds | +| | ... | | | | | | | | | Etc. | + +| | | | | | | | | | | | +|--------------|-------|--|--|--|--|--|--|--|--|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | 25-40 | | | | | | | | | For ping test 0001, these bytes can be either delay measurements or padding.
For extended ping, these bytes contain the actual IP address that was pinged, 4 bytes for IPv4, 16 bytes for IPv6. If the network address was not resolvable, the ONU should set these bytes to all zeroes. | +| OMCI trailer | 41-48 | | | | | | | | | | + +If xxx = 010 (time exceeded – traceroute), the remainder of the message contains the following content. In PON applications, it is not expected that a route trace will exceed the available space in the message, but if it does, the more distant responses should be dropped. There is only enough space in the message body for a single IPv6 address. + +| | | | | | | | | | | | +|--------------|--------|--|--|--|--|--|--|--|--|--------------------------------------------| +| | 11-14 | | | | | | | | | IP address of the nearest neighbour | +| | 15-18 | | | | | | | | | IP address of the second nearest neighbour | +| | ... | | | | | | | | | Etc. | +| | ...-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +If xxx = 011 (unexpected ICMP response), the remainder of the message contains the following content: + +| | | | | | | | | | | | +|--------------|-------|--|--|--|--|--|--|--|--|------------------------------------------------------------| +| | 11 | | | | | | | | | Type | +| | 12 | | | | | | | | | Code | +| | 13-14 | | | | | | | | | Checksum | +| | 15-18 | | | | | | | | | Bytes 5-8 of ICMP message (meaning depends on type/code) | +| | 19-40 | | | | | | | | | Internet header + 64 bits of original datagram (truncated) | +| OMCI trailer | 41-48 | | | | | | | | | | + +#### A.3.39.5 Format for optical line supervision test action invoked against ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier or RE downstream amplifier entity class + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|----------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|---------------------------|-------|---|---|---|---|---|---|---|---|------------------------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to ANI-G, RE ANI-G, PPTP RE UNI, RE upstream amplifier or RE downstream amplifier entity class. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | Type = 1, power feed voltage | +| | 10-11 | | | | | | | | | Volts, 2s complement, 20 mV resolution | +| | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | Type = 3, received optical power | +| | 13-14 | | | | | | | | | Decibel-microwatts, 2s complement, 0.002 dB resolution (Coding –32768 to +32767, where 0x00 = 0dBuW, 0x03e8 = +2dBuW, etc.) | +| | 15 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | Type = 5, Mean optical launch power | +| | 16-17 | | | | | | | | | Decibel-microwatts, 2s complement, 0.002 dB resolution (Coding –32768 to +32767, where 0x00 = 0dBuW, 0x03e8 = +2dBuW, etc.) | +| | 18 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | Type = 9, laser bias current | +| | 19-20 | | | | | | | | | Unsigned integer, 2 µA resolution | +| | 21 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | Type 12, temperature, degrees Celsius | +| | 22-23 | | | | | | | | | 2s complement, 1/256 °C resolution | +| | 24-25 | | | | | | | | | Pointer to a general purpose buffer ME. Valid only for vendor-specific tests that require a GP buffer. | +| | 26-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +NOTE – Unsupported tests are indicated with test type indicator 0 and 2 bytes of 0 data. + +#### A.3.39.6 Format for test action invoked against dot1ag MEP entity class, loopback test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to the dot1ag MEP entity class. | +| | 7-8 | | | | | | | | | Entity instance | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | | | | | | | | | | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = 1: indicates failure to receive any loopback replies (LBRs) within 5 s | +| | 10-11 | | | | | | | | | Valid LBRs count: the number of valid, in-order LBRs received. | +| | 12-13 | | | | | | | | | Out of order LBRs count: the number of valid LBRs received that were out of order. | +| | 14-15 | | | | | | | | | Mismatch LBRs count: the number of received LBRs whose MAC SDU did not match that of the corresponding LBM (except for opcode). Optional feature, set to 0xFF if not supported. | +| | 16-19 | | | | | | | | | Delay from LB message transmission to LB response reception, measured in microseconds. The value 0 indicates no information available. | +| | 20-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +#### A.3.39.7 Format for test action invoked against dot1ag MEP entity class, linktrace test + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | | | | | | | | | | +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 0 | | | | | | DB = 0, AR = 0, AK = 0
bits 5-1: action = test result | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class.
NOTE – This message format pertains to the dot1ag MEP entity class. | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | x | x = 1: indicates failure to receive any linktrace replies (LTRs) within 5 s | +| | 10-13 | | | | | | | | | Transaction ID of transmitted LTM | +| | 14-21 | | | | | | | | | Content of egress TLV data field in transmitted LTM ([IEEE 802.1ag], clause 21.8.8). The LTRs themselves are captured in the general purpose buffer designated by the test command. | +| | 22-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +#### A.3.40 Get current data + +Based on the size of the message contents field, the aggregate size of the attributes requested by a single get current data command should not exceed 25 bytes. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|---------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 1 | 0 | | | | | | DB = 0, AR = 1, AK = 0
bits 5-1: action = get current data | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9-10 | | | | | | | | | Attribute mask | +| | 11-40 | | | | | | | | | Zero padding | +| OMCI trailer | 41-48 | | | | | | | | | | + +### A.3.41 Get current data response + +Bytes 37 to 40 are always reserved for the optional attribute and attribute execution masks; however, the contents of these bytes are only valid in conjunction with the 1001 encoding used to indicate failed or unknown attributes. + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|------------------------------------|-------|---|---|---|---|---|---|---|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transaction correlation identifier | 1-2 | | | | | | | | | | +| Message type | 3 | 0 | 0 | 1 | | | | | | DB = 0, AR = 0, AK = 1
bits 5-1: action = get current data | +| Device identifier | 4 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | OMCI = 0x0A | +| Managed entity identifier | 5-6 | | | | | | | | | Entity class | +| | 7-8 | | | | | | | | | Entity instance | +| Message contents | 9 | 0 | 0 | 0 | 0 | x | x | x | x | Result, reason
0000 command processed successfully
0001 command processing error
0010 command not supported
0011 parameter error
0100 unknown managed entity
0101 unknown managed entity instance
0110 device busy
1001 attribute(s) failed or unknown | +| | 10-11 | | | | | | | | | Attribute mask | +| | 12-n | | | | | | | | | Attribute value of first attribute included (size depending on the type of attribute) | +| | | | | | | | | | | ... | +| | | | | | | | | | | Attribute value of last attribute included (size depending on the type of attribute) | +| | xx-36 | | | | | | | | | Zero padding | + +| Field | Byte | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Comments | +|--------------|-------------|----------|----------|----------|----------|----------|----------|----------|----------|-----------------------------------------------------------------------------------------------| +| | 37-38 | | | | | | | | | Optional attribute mask, used with 1001 encoding:
0 = default
1 = unsupported attribute | +| | 39-40 | | | | | | | | | Attribute execution mask, used with 1001 encoding:
0 = default
1 = failed attribute | +| OMCI trailer | 41-48 | | | | | | | | | | + +## Annex B + +### OMCI in ITU-T PON systems + +(This annex forms an integral part of this Recommendation.) + +#### B.1 Establishing the ONU management and control channel (OMCC) + +This clause should be read in conjunction with the respective TC layer specification, as applicable to the system under consideration. + +Upon initialization, the ONU creates a default alloc-ID for the OMCC. The default alloc-ID neither requires nor uses a T-CONT. The following discussion explains when a T-CONT may meaningfully be associated with the default alloc-ID. + +The establishment of the OMCC follows the process shown in Figure B.1-1. During activation, the ONU receives a PLOAM message from the OLT indicating the assignment of the ONU-ID. The ONU creates the default alloc-ID with the same value as the ONU-ID. It is therefore not necessary for the OLT to send an assign\_alloc-ID message to establish the OMCC. If the OLT nevertheless chooses to send an assign\_alloc-ID PLOAM with the default alloc-ID, the ONU should acknowledge this message without taking any specific further action. This is true regardless of the alloc-ID type value in the assign\_alloc-ID message: it is not allowed to de-allocate the default alloc-ID with an assign\_alloc-ID type 255 message. + +Upon completion of ONU activation in ITU-T G.984 systems, the OLT assigns a GEM port-ID to the ONU for OMCI messages. This is accomplished by a configure\_port-ID PLOAM message. The ONU maps the OMCI port-ID attribute to OMCC traffic and the default alloc-ID, and responds back to the OLT with an AK. + +In subsequent ITU-T systems, the GEM port for OMCI use is automatically assigned, and is equal to the ONU-ID. + +At this point, the OMCC path has been successfully established. + +![Sequence diagram illustrating the OMCC establishment process between an OLT and an ONU.](3ca9eaf629af92d7d10c993c093067bf_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: Registration process + OLT->>ONU: Assign_ONU-ID PLOAM message + Note right of ONU: ONU sets OMCI alloc-ID to ONU-ID +ITU-T G.987: ONU sets OMCI GEM port to ONU-ID. + ONU->>OLT: Ranging grant + OLT->>ONU: ITU-T G.984: serial_number_ONU PLOAM message +ITU-T G.987: Registration PLOAM message + ONU->>OLT: Ranging_time PLOAM message + OLT->>ONU: ITU-T G.987: Acknowledge PLOAM message + OLT->>ONU: ITU-T G.984: Configure_port-ID PLOAM message + Note right of ONU: ITU-T G.984: ONU sets OMCI GEM port + ONU->>OLT: ITU-T G.984: Acknowledge PLOAM message + Note right of ONU: G.988(12)_FB.1-1 +``` + +The diagram illustrates the sequence of messages for OMCC establishment. It starts with a 'Registration process' on the OLT side. The OLT sends an 'Assign\_ONU-ID PLOAM message' to the ONU. The ONU responds with a 'Ranging grant'. The OLT then sends 'ITU-T G.984: serial\_number\_ONU PLOAM message' and 'ITU-T G.987: Registration PLOAM message'. The ONU replies with 'Ranging\_time PLOAM message'. The OLT sends 'ITU-T G.987: Acknowledge PLOAM message'. The OLT then sends 'ITU-T G.984: Configure\_port-ID PLOAM message'. The ONU responds with 'ITU-T G.984: Acknowledge PLOAM message'. Internal ONU actions include 'ONU sets OMCI alloc-ID to ONU-ID' and 'ITU-T G.987: ONU sets OMCI GEM port to ONU-ID' after the first message, and 'ITU-T G.984: ONU sets OMCI GEM port' after the configure message. A vertical double-headed arrow on the right is labeled 'OMCI connection setup'. The diagram is labeled 'G.988(12)\_FB.1-1' at the bottom right. + +Sequence diagram illustrating the OMCC establishment process between an OLT and an ONU. + +Figure B.1-1 – OMCC establishment + +While it is not forbidden, it is not recommended that the default alloc-ID be used to carry subscriber traffic. If subscriber traffic is nevertheless to be carried in the default alloc-ID, this alloc-ID must be mapped to a T-CONT through normal OMCI messages. + +OMCI traffic then consumes bandwidth allocated to the designated alloc-ID, but with strictly higher priority than all other traffic in the same alloc-ID. DBA reports for such a dual-purpose alloc-ID include both OMCI and subscriber traffic queues. + +A T-CONT shared with the OMCC can be deallocated for subscriber traffic, in which case it disappears from the MIB view of the ONU. OMCC traffic over the default alloc-ID cannot be removed, deleted or redirected. + +After the OMCC has been established, it is possible for the OLT to enable encryption on the OMCC GEM port. In ITU-T G.984 systems, this is accomplished by the OLT sending an *encrypted\_port-ID* PLOAM that names the OMCC GEM port. + +In subsequent PON systems, port encryption is normally established through the corresponding GEM port network CTP. The OMCC has no such associated ME, so it relies on defaults. If the GEM frame itself contains an encryption key index, it is understood to refer to the unicast key and to require encryption both up- and downstream. OMCI message channel failure may indicate the absence or miscoordination of unicast keys. + +Regardless of OMCC encryption, OMCI messages are protected by an MIC, whose computation is specified in the relevant TC layer specification. + +## **B.2 OMCI handling within the ONU** + +Message response times should not exceed 1 s. The message definition considers cases where command execution may take longer than this. For example, in executing tests, the ONU acknowledges the test command from the OLT within the required 1 s, then initiates an autonomous test result message at some later time when the test is complete. Another example is the case where downloaded software may take some significant time to write into a non-volatile store; in this case, the ONU responds to the end download command from the OLT with a device busy code and the OLT retries periodically until the operation is complete. + +### **B.2.1 Message flow control and error recovery** + +NOTE – Prioritized message handling is defined only for the baseline OMCI message set. In the context of the extended message set, this clause should be read with the understanding that there is only one priority class. + +The flow control/error recovery procedures for message exchange over the OMCC are based on a simplex acknowledged transaction stop-and-wait mechanism that can be extended to support concurrent execution of multiple transaction requests of different priority levels. These flow control procedures ensure that a low level acknowledged transaction request transmitted from the OLT has been properly received and processed to completion by the ONU before the next message of the same priority level is sent by the OLT. The stop-and-wait protocol uses the transaction correlation identifier field, retry counter(s) and applicable transaction request timer(s) to control the message flow rate while relying on an MIC to verify the data integrity of all received messages. + +When a transaction request message of priority level $i$ is sent to an ONU, a transaction request timer $T_i$ is started. Timer $T_i$ is stopped upon receipt of an AK message containing the same transaction correlation identifier value. If a valid AK message is not received by the OLT after timer $T_i$ expires at time $T_{maxi}$ , the OLT re-sends the original transaction request message. A retransmitted acknowledged transaction request message carries the same transaction correlation ID as the original message. + +Retry counter $R_i$ is defined at priority level $i$ . Upon the first transmission of a new command at priority $i$ , $R_i$ is initialized to zero, and each time an acknowledged transaction request message is retransmitted, the OLT increments $R_i$ . When $R_i$ reaches the maximum retry value, $R_{maxi}$ , the OLT stops retransmitting the message and declares an OMCC link state error. + +These timers ( $T_i$ ) and retry counters ( $R_i$ ) are only maintained within the OLT and do not exist within the ONU. Threshold values for timer expiration ( $T_{maxi}$ ) and number of retries ( $R_{maxi}$ ) are not subject to standardization. It is suggested that the default threshold values of both $T_{max}$ and $R_{max}$ be independently configurable for each priority level. The default value for the high priority $T_{max}$ should account for the typical message transmission delay plus the command message response time. + +These flow control/error recovery procedures are illustrated in Figure B.2.1-1 for a case where the OMCC link is not permanently broken. First, the OLT sends an acknowledged transaction request (message 1) with priority level 0. While message 1 is outstanding, the OLT issues message 2 with priority level 1. Both of these commands are received and executed with the associated response messages returned to the OLT by the ONU. The AK for message 1 is received by the OLT in time; however, the response to message 2 is lost and never received. The OLT detects that something went wrong because timer $T_1$ expires, and the OLT therefore retransmits the original command (message 2). From the identical transaction ID, the ONU detects that this retransmitted command is identical to the last received priority level 1 command and therefore does not re-execute it. The ONU simply retransmits the original response from the previous execution of message 2, which in Figure B.2.1-1 reaches the OLT in time. + +The final transaction in the example shows the case where the OLT sends an acknowledged transaction request (message 3) with priority level 0, but the message itself gets lost and is never properly received by the ONU. After the associated timer ( $T_0$ ) expires, the OLT retransmits the command and now all goes well. + +![Sequence diagram showing concurrent message exchange with error recovery between OLT and ONU. The diagram illustrates three message exchanges with timers T0 and T1. It shows successful delivery, lost replies with retransmission and duplicate detection, and lost requests with retransmission and execution.](b6a1b0707decc2aedee3b44d70a2c5ae_img.jpg) + +``` + +OLT ONU + | | + | Start T₀ | + |---------- Message 1/Priority 0/AR = 1/AK = 0/TID = 1234 -------->| Execute + | | message 1 + |<--------- Message 1 reply/Priority 0/AR = 0/AK = 1/TID = 1234 --| + | Stop T₀ | + | (< Tmax₀) | + | | + | Start T₁ | + |---------- Message 2/Priority 1/AR = 1/AK = 0/TID = 8123 -------->| Execute + | | message 2 + | X <-- Message 2 reply/Priority 1/AR = 0/AK = 1/TID = 8123 + | | + | T₁ expires | + | (≥ Tmax₁) | + | | + | Re-send message 2 | + | Increment R₁ | + | Start T₁ | Discard message 2 + |---------- Message 2/Priority 1/AR = 1/AK = 0/TID = 8123 -------->| (do not re-execute) + | | + |<--------- Message 2 reply/Priority 1/AR = 0/AK = 1/TID = 8123 --| + | Stop T₁ | + | (< Tmax₁) | + | | + | Start T₀ | + |---------- Message 3/Priority 0/AR = 1/AK = 0/TID = 1235 ---X | + | | + | T₀ expires | + | (≥ Tmax₀) | + | | + | Re-send message 3 | + | Increment R₀ | Execute + | Start T₀ | message 3 + |---------- Message 3/Priority 0/AR = 1/AK = 0/TID = 1235 -------->| + | | + |<--------- Message 3 reply/Priority 0/AR = 0/AK = 1/TID = 1235 --| + | Stop T₀ | + | (< Tmax₀) | + | | + G.988(12)_FB.2.1-1 + +``` + +Sequence diagram showing concurrent message exchange with error recovery between OLT and ONU. The diagram illustrates three message exchanges with timers T0 and T1. It shows successful delivery, lost replies with retransmission and duplicate detection, and lost requests with retransmission and execution. + +**Figure B.2.1-1 – Concurrent message exchange with error recovery** + +A case where the OMCC link is effectively broken (link down) is shown in Figure B.2.1-2. + +![Sequence diagram illustrating OMCC link error detection between an OLT and an ONU. The OLT sends three identical messages (Message 4/Priority 0/AR = 1/AK = 0/TID = 1236) to the ONU. Each message is followed by a timeout T0. If the timeout expires (≥ Tmax0), the OLT re-sends the message and increments R0. After the third re-send, the OLT declares a link error. The ONU receives all three messages but does not respond, indicated by 'X' marks on its timeline.](649db563f545d0dccc6d518baf536453_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: Start T0 + OLT->>ONU: Message 4/Priority 0/AR = 1/AK = 0/TID = 1236 + Note left of OLT: T0 expires (≥ Tmax0) + Note left of OLT: Re-send message 4 + Note left of OLT: Increment R0 + Note left of OLT: Start T0 + OLT->>ONU: Message 4/Priority 0/AR = 1/AK = 0/TID = 1236 + Note left of OLT: T0 expires (≥ Tmax0) + Note left of OLT: Re-send message 4 + Note left of OLT: Increment R0 + Note left of OLT: Start T0 + OLT->>ONU: Message 4/Priority 0/AR = 1/AK = 0/TID = 1236 + Note left of OLT: T0 expires + Note left of OLT: Declare link error + +``` + +G.988(17)\_FB.2.1-2 + +Sequence diagram illustrating OMCC link error detection between an OLT and an ONU. The OLT sends three identical messages (Message 4/Priority 0/AR = 1/AK = 0/TID = 1236) to the ONU. Each message is followed by a timeout T0. If the timeout expires (≥ Tmax0), the OLT re-sends the message and increments R0. After the third re-send, the OLT declares a link error. The ONU receives all three messages but does not respond, indicated by 'X' marks on its timeline. + +**Figure B.2.1-2 – OMCC link error detection** + +## B.2.2 Prioritized protocol entities + +NOTE 1 – Prioritized message handling is defined only for the baseline message set. In the context of the extended message set, this clause should be read with the understanding that there is only one priority class. + +This clause specifies the behaviour of the ONU more precisely than in the preceding clause with respect to the prioritized request mechanism of the OMCC. + +Conceptually, the way the ONU handles the OMCC requests can be illustrated by referring to the dual priority level implementation example shown in Figure B.2.2-1. + +When the ONU receives a GEM frame via the GEM port associated with the management channel, it calculates the MIC and compares it with the value found in the OMCI trailer. If the values do not match, the ONU discards the message. It is recommended that this event be logged by the ONU and possibly communicated to the OLT by an out-of-band mechanism but, as far as the protocol is concerned, the message is discarded silently. + +NOTE 2 – Loss of encrypted OMCI communications with an otherwise functional ONU may indicate lost or corrupt keys. The OLT is advised to renegotiate keys or to fall back to an unencrypted OMCI as the first steps in diagnosing the trouble. + +Messages with a correct MIC are then placed into either of two distinct incoming message queues, according to the high or low priority level of the associated command encoded in the MSB of the transaction correlation identifier field. If the associated incoming message queue is already full, the ONU discards the message. It is recommended that this event be logged by the ONU and possibly communicated to the OLT by an out-of-band mechanism but, as far as the protocol is concerned, the message is discarded silently. + +There are two distinct incoming command processing protocol entities, one associated with each priority level, which serve messages sequentially from independent incoming queues. Each protocol entity can execute concurrently. If a message is a one-way (unacknowledged) command, the protocol entity simply executes the command. If a message is an acknowledged command, the protocol entity + +must first look at the transaction correlation identifier. If it is not equal to the transaction correlation identifier of the last executed command with the same priority level, the protocol entity executes the command and places the response/acknowledgement, with an identical transaction correlation identifier, in the outgoing queue of the same priority level. If the transaction correlation identifier is equal to that of the last executed command with the same priority level (the case where the OLT retransmits a command due to a lack of proper acknowledgement), the protocol entity does not actually execute the command but simply places the response from the last execution of that command in the outgoing queue to resend the previous acknowledgement response. In both cases, the command processing protocol entity for a given priority level should block until there is room in the associated outgoing queue for the response message. + +In the upstream direction, requests by ONU applications to send autonomous event notifications simply result in the corresponding messages being directed to an event notification protocol entity for transmission to the OLT. The event notification protocol entity forwards these event notification messages to the low priority outgoing queue. In this case as well, the event notification protocol entity should block until there is room in the low priority outgoing queue to hold the notification message. The MIC generator removes messages from the outgoing queues using a strict priority discipline (that is, the low-priority queue is served only when the high-priority queue is empty), generates an MIC, formats the packet as either a baseline or an extended message, depending on which form is in use, and transmits the message to the OLT. + +![Diagram of protocol entities within the ONU showing data flow from Applications through protocol entities and queues to MIC generation and validation.](8fed6487f82678a66c8412eddc5b09fd_img.jpg) + +The diagram illustrates the internal architecture of an ONU. On the right, a box labeled 'Applications' has bidirectional connections to three protocol entities: 'Event notification protocol entity', 'High priority protocol entity', and 'Low priority protocol entity'. The 'Event notification protocol entity' sends data to a 'Low priority queue'. The 'High priority protocol entity' sends data to a 'High priority queue'. The 'Low priority protocol entity' sends data to a 'Low priority queue'. Both 'High priority queue' and 'Low priority queue' boxes are shown twice. The first set of queues receives data from the protocol entities and sends it to a 'MIC generation' block. The 'MIC generation' block has an outgoing arrow to the left. The second set of queues receives data from a 'MIC validation' block on the left. From the 'MIC validation' block, a dashed arrow points downwards labeled 'Possible discard', and a solid arrow points to the second 'High priority queue'. + +Diagram of protocol entities within the ONU showing data flow from Applications through protocol entities and queues to MIC generation and validation. + +**Figure B.2.2-1 – Protocol entities within the ONU** + +### B.2.3 Restrictions on actions in relation to the protocol entities + +To reduce the complexity and the amount of memory necessary in the ONU, the OLT is not allowed to issue an MIB upload or a software download of a certain priority level while a similar action in the other priority level is in progress. + +### B.2.4 Use of the default alloc-ID + +The upstream OMCC is carried in the default allocation\_ID. In some implementations, the default alloc\_ID is also used for user traffic, and is associated with a T-CONT ME. In these cases, the OMCC traffic is combined with the user traffic using simple strict priority multiplexing, with the OMCC having a higher priority. + + + +## C.2 Encapsulating OMCI messages in Ethernet frames + +The extended OAM frame defined in IEEE 802.3 is used for the EPON OMCI frame format. Figure C.2-1 shows the extended OAM frame for EPON OMCI. + +![](110c9de422c32d44a20bf86a5f43b42c_img.jpg) + +Extended OMCI message - variable length up to 1493 bytes + +| | | | | | | | +|----------------------------------------------|-----------------------|----------------------------|-------------------------------------|-----------------------------------|-----------------------------|----------------| +| Transaction correlation identifier (2 bytes) | Message type (1 byte) | Device identifier (1 byte) | Managed entity identifier (4 bytes) | Message contents length (2 bytes) | Message contents (variable) | MIC (excluded) | +|----------------------------------------------|-----------------------|----------------------------|-------------------------------------|-----------------------------------|-----------------------------|----------------| + +OMCI Ethernet frame + +| | | | | | | | | | | +|---------------------------------|-----------------------------------|------------------------------|----------------------------------|------------------|-----------------|---------------|---------------|--------------|--------------------------------| +| Preamble and LLID/SFD (8 bytes) | Destination MAC address (6 bytes) | Source MAC address (6 bytes) | Extended OAM Ethertype (2 bytes) | Subtype (1 byte) | Flags (2 bytes) | Code (1 byte) | OUI (3 bytes) | OMCI message | Frame check sequence (4 bytes) | +|---------------------------------|-----------------------------------|------------------------------|----------------------------------|------------------|-----------------|---------------|---------------|--------------|--------------------------------| + +Preamble and LLID (EPON) + +| | | | | | | | | +|---------------|---------------|---------------|---------------|---------------|-----------------------------------------|----------------------------------|---------------| +| 0x55 (1 byte) | 0x55 (1 byte) | 0xd5 (1 byte) | 0x55 (1 byte) | 0x55 (1 byte) | (1 byte) | (1 byte) | CRC8 (1 byte) | +|---------------|---------------|---------------|---------------|---------------|-----------------------------------------|----------------------------------|---------------| + +Coverage of CRC8 + +G.988(10)\_FC.2-1 + +**Figure C.2-1 – Extended OAM frame structure for EPON OMCI** + +The extended OAM frame format and fields for the OMCI are defined in Table C.2-1. + +**Table C.2-1 – Extended OAM frame format and fields for EPON OMCI** + +| Field | Length | Definition | Value | +|--------------------------|------------------|-----------------------------------------------------------------------------------|-----------------------------------------------| +| Preamble and LLID/SFD | 8 bytes | Defined in clause 4.2 and clause 76 of [IEEE 802.3] | LLID is assigned during ONU discovery process | +| Destination MAC address | 6 bytes | Destination MAC address | 0x0180C2000002 | +| Source MAC address | 6 bytes | Source MAC address | MAC address of source equipment | +| Ethertype | 2 bytes | Clause 57 of [IEEE 802] | 0x8809 (Slow protocol) | +| Subtype | 1 byte | Clause 57 of [IEEE 802] | 0x03 (OAM) | +| Flags | 2 bytes | Clause 57 of [IEEE 802] | | +| Code | 1 byte | Clause 57 of [IEEE 802] | 0xFE | +| OUI | 3 bytes | ITU-T OUI | 0x0019A7 | +| OMCI message | up to 1493 bytes | Defined in clauses 11 and A.2.
Extended OMCI message
Excludes MIC (4 bytes) | | +| Frame check sequence FCS | 4 bytes | Defined in [IEEE 802.3] | | + +### C.3 Relationship between the OMCI and OAM defined in clause 57 of [IEEE 802.3] + +Clause 57 of [IEEE 802.3] describes OAM as an optional function. Items described in this clause can be covered by the OMCI. In most cases, an ITU-T G.988 support system does not need to support clause 57 of [IEEE 802.3] OAM; however, it is a system dependent matter. + +**Table C.3-1 – Relationship between clause 57 of [IEEE 802.3] OAM and OMCI** + +| No. | Items in clause 57 of [IEEE 802.3] | Corresponding OMCI functionalities | +|-----|------------------------------------|---------------------------------------------------------------------------------------------------------| +| 1 | Information | This item is the OAM channel set-up procedure. It is provided by the OMCC initial set-up procedures. | +| 2 | Event notification | This item is alarm notification. It is provided by the alarm notification function defined in the OMCI. | +| 3 | Variable request/response | This item can be interpreted as MIB get/set. The OMCI supports the same functions. | +| 4 | Loopback control | This item is provided by OMCI loopback control. | + +### C.4 Adaptation of the G-PON information model to EPON + +#### C.4.1 Overview + +Table 8-1 lists the MEs that are mandatory or not applicable for EPON systems. Some MEs are redefined in this clause for use in EPON. + +MEs on the ANI side were originally defined for the G-PON system architecture. In an EPON system, the PON framing protocol is different from G-PON or XG-PON. To adapt the OMCI to an EPON system, the following interpretations are required. + +In EPON, GEM ports and T-CONTs are not defined, because EPON conveys Ethernet frames transparently in the PON section. However, these differences can be absorbed by the interpretation shown in Table C.4-1. On the other hand, the MEs on the UNI side are usable without modification. + +**Table C.4-1 – Interpretation of ANI-side MEs** + +| No. | Items | Interpretation in EPON system | +|-----|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | GEM port | The concept of GEM port is interpreted as a layer 2 flow, such as VLAN or CoS. In an EPON system, GEM port network CTP and GEM interworking termination point MEs exist for binding the layer 2 flows and priority queue MEs and the MAC bridge ME. | +| 2 | T-CONT | The T-CONT is the unit of bandwidth assignment. In an EPON system, the unit of bandwidth assignment is the logical link. | + +For providing an Ethernet service to users in a PON system, + +- G-PON/XG-PON1: Ethernet flows are encapsulated by GEM/XGEM in the PON section. +- EPON/10G-EPON: Ethernet flows are transparently conveyed in the PON section. + +Except for GEM encapsulation, there is no difference between G-PON and EPON. MEs on the UNI side are compatible in both systems. Both systems require QoS configuration, cross-connection, filtering, VLAN operation etc., for each layer 2 service flow. + +![Diagram of Layer 2 flows in G-PON ONU showing downstream and upstream traffic paths through MEs and GEM ports.](a4de814f6aad47c148e3f0e6edb48c55_img.jpg) + +The diagram illustrates the Layer 2 flows in a G-PON ONU, divided into Downstream and Upstream paths. + +- Downstream Path:** Traffic from the UNI (via PPTP) enters the ONU and is directed to "MEs on the UNI side (eg. L2 data service)". These MEs are connected to "PQs, downstream" (Priority Queues). An arrow points from the PQs to a box containing "GEM port Interworking TP" and "Network CTP". Below this is another "GEM port". An arrow labeled "Extracting L2 flow from GEM port" points from the second GEM port back to the MEs. A callout box above the first GEM port lists "VLAN operation, filtering, cross connection, priority mapping, rate limiting, etc.". The label "Downstream" is on the right. +- Upstream Path:** Traffic from the UNI (via PPTP) enters the ONU and is directed to "MEs on the UNI side (eg. L2 data service)". These MEs are connected to a box labeled "Mapping L2 flow to GEM port", which contains two "GEM ports". Arrows point from these GEM ports to "PQs, upstream" (Priority Queues). From the PQs, the traffic flows through a "T-CONT" and an "ANI" (Access Network Interface). A callout box below the MEs lists "VLAN operation, filtering, cross connection, priority mapping, rate limiting, etc.". The label "Upstream" is on the left. + +G.988(10)\_FC4.1-1 + +Diagram of Layer 2 flows in G-PON ONU showing downstream and upstream traffic paths through MEs and GEM ports. + +**Figure C.4.1-1 – Layer 2 flows in G-PON ONU** + +By introducing the concept of a virtual GEM port into the OMCI, the MEs in this Recommendation can be re-used for EPON. In G-PON, a GEM port is defined to convey each layer 2 flow. The GEM port network CTP connects the MAC bridge port and upstream/downstream priority queues in the ONU for an Ethernet service. EPON requires the same configuration of connectivity between the MAC bridge port and upstream/downstream priority queues. By configuring the GEM ports virtually, G-PON and EPON are compatible in the OMCI. A virtual GEM port exists for the purpose of connecting the MAC bridge port and priority queue. GEM port network CTP and GEM IW TP MEs are created for the ME pointer relationship. + +What this means is that the GEM port network CTP is re-used in EPON, but the value of the GEM port attribute is not used. It is suggested that it be set to 0 by the OLT, and it must be ignored by the ONU. + +![Diagram of Virtual GEM ports in EPON ONU showing downstream and upstream traffic flows between UNI, PTP, MEs, and GEM ports.](157b9aaba9418b037266b482404acae7_img.jpg) + +The diagram illustrates the internal architecture of an EPON ONU. On the left, two UNI (User Network Interface) units are connected to a PTP (Physical Termination Point). The PTP branches into two main processing paths. The top path represents 'Downstream' traffic, where data flows from the PTP through 'MEs on the UNI side (eg. L2 data service)' into a 'Virtual GEM port' block. This block contains an 'Interworking TP' and a 'Network CTP'. Above this block, a callout indicates 'VLAN operation, filtering, cross connection, priority mapping, rate limiting, etc.'. The bottom path represents 'Upstream' traffic, where data flows from the PTP through 'MEs on the UNI side (eg. L2 data service)' into a 'Virtual GEM ports' block. This block also has a callout for 'VLAN operation, filtering, cross connection, priority mapping, rate limiting, etc.'. Both Virtual GEM port blocks lead to 'PQs, downstream' and 'PQs, upstream' (Priority Queues). The upstream PQs then connect to a 'T-CONT (Logical link) ANI' (Allocation Number Interface). Brackets on the left and right are labeled 'L2 flows'. The diagram is labeled 'G.988(10)\_FC4.1-2' in the bottom right corner. + +Diagram of Virtual GEM ports in EPON ONU showing downstream and upstream traffic flows between UNI, PTP, MEs, and GEM ports. + +**Figure C.4.1-2 – Virtual GEM ports in EPON ONU** + +## C.4.2 ME definitions + +This clause modifies certain MEs from their definitions in clause 9. Where no change is noted, the clause 9 definition remains applicable. + +### C.4.2.1 Clause 9.2.3: GEM port network CTP + +This ME represents the termination of a GEM port on an ONU. In an EPON system, the GEM port exists virtually for keeping the pointer relationship. The value of the port-ID attribute is "don't care", because it does not represent an actual Port-ID. The optional attributes encryption state and encryption key ring are not used in an EPON system for the same reason. + +#### Relationships + +No change required. + +#### Attributes + +Table C.4.2.1-1 summarizes the attributes of the GEM port network CTP for EPON. + +**Table C.4.2.1-1 – Attributes of GEM port network CTP** + +| Attributes | R/W, M/O | Definition changes in EPON | +|-----------------------------------------|-----------------------------------|------------------------------------------------------------------------| +| Managed entity ID | (R, set-by-create) (mandatory) | No change required. | +| Port-ID | (R, W, set-by-create) (mandatory) | Don't care. Recommended to be set to 0 by OLT. Must be ignored by ONU. | +| T-CONT pointer | (R, W, set-by-create) (mandatory) | T-CONT represents logical link in EPON. | +| Direction | (R, W, set-by-create) (mandatory) | No change required. | +| Traffic management pointer for upstream | (R, W, set-by-create) (mandatory) | No change required. | + +**Table C.4.2.1-1 – Attributes of GEM port network CTP** + +| Attributes | R/W, M/O | Definition changes in EPON | +|---------------------------------------------------|-----------------------------------|----------------------------| +| Traffic descriptor profile pointer for upstream | (R, W, set-by-create) (optional) | No change required. | +| UNI counter | (R) (optional) | No change required. | +| Priority queue pointer for downstream | (R, W, set-by-create) (mandatory) | No change required. | +| Encryption state | (R) (optional) | Not used. | +| Traffic descriptor profile pointer for downstream | (R, W, set-by-create) (optional) | No change required. | +| Encryption key ring | (R, W, set-by-create) (optional) | Not used. | + +*Actions* + +No change required. + +*Notifications* + +End-to-end loss of continuity (optional) is not used in EPON. + +**C.4.2.2 Clause 9.2.4: GEM interworking termination point** + +An instance of this ME represents a point in the ONU where the IW of a bearer service (usually Ethernet) to the GEM layer takes place. In an EPON system, the GEM port exists virtually, only for keeping pointer relationships. IW option attribute values are limited because there is no actual IW function. The value of the GAL profile pointer is null because there is no GAL profile in EPON. Likewise, the value of GAL loopback configuration is always 0 (no loopback). + +*Relationships* + +No change required. + +*Attributes* + +Table C.4.2.2-1 summarizes the attributes of the GEM IW TP for EPON. + +**Table C.4.2.2-1 – Attributes of the GEM interworking termination point** + +| Attributes | R/W, M/O | Definition changes in EPON | +|-------------------------------------------|-----------------------------------|--------------------------------------------------------------------------------------------------------------------------------------| +| Managed entity ID | (R, set-by-create) (mandatory) | No change required. | +| GEM port network CTP connectivity pointer | (R, W, set-by-create) (mandatory) | No change required. | +| Interworking option | (R, W, set-by-create) (mandatory) | 0 Reserved
1 MAC bridged LAN
2 Reserved
3 Reserved
4 Reserved
5 802.1p mapper
6 Downstream broadcast
7 Reserved | + +**Table C.4.2.2-1 – Attributes of the GEM interworking termination point** + +| Attributes | R/W, M/O | Definition changes in EPON | +|----------------------------------------|--------------------------------------|-----------------------------------------------| +| Service profile pointer | (R, W, set-by-create)
(mandatory) | No change required. | +| Interworking termination point pointer | (R, W, set-by-create)
(mandatory) | No change required. | +| PPTP counter | (R) (optional) | No change required. | +| Operational state | (R) (optional) | No change required. | +| GAL profile pointer | (R, W, set-by-create)
(mandatory) | Not used. Set to 0 by OLT,
ignored by ONU. | +| GAL loopback configuration | (R, W) (mandatory) | Fixed value 0x00 (No loopback) | + +*Actions* + +No change required. + +*Notifications* + +No change required. + +# Appendix I + +## OMCI common services + +(This appendix does not form an integral part of this Recommendation.) + +This appendix describes the common services of the OMCI. + +NOTE – Although this appendix describes capabilities that are intended to be common to any technology that employs the OMCI, some information in this appendix should be modified appropriately when applied to [ITU-T G.986]. + +Common services comprise: + +- a) ONU MIB management; +- b) equipment management; +- c) software upgrade; +- d) performance monitoring. + +These services are explained with the aid of scenario diagrams. + +### I.1 ONU MIB management + +An ONU contains data known as an MIB that reflects its hardware configuration and whatever service provisioning may have been done. + +Viewing an access system as a distributed system, it is important that the OLT retain its own view of the ONU, e.g., if the ONU needs to be replaced, and that the OLT's view remains synchronized with the ONU's own MIB. + +The results of external events such as DHCP queries or adapting to subscriber interfaces are also visible via OMCI get commands or AVCs. The OLT is normally also interested in this transient information, but transient information synchronization is beyond the scope of this clause. In general, the OLT is expected to use a variety of techniques including AVCs, alarms, including indications from the TC layer, periodic retrievals, or features such as snooping of protocols (e.g., IGMP) for this information. + +#### I.1.1 MIB discovery + +##### I.1.1.1 OMCI capability report option + +The OLT may discover the ONU's software capability and a summary of its existing provisioning by querying the two table attributes contained in the optional OMCI ME of clause 9.12.8, and the contents of the ME instances. + +The OLT may obtain the ME types supported by the ONU through the ME type table attribute of the OMCI ME. The OLT may then obtain the MTs supported by the ONU through the MT attribute of the OMCI ME. + +The OLT may obtain further details about the ONU's support for a given OMCI ME, as well as a summary of existing instances of that ME type by reading the ME for that ME. Refer to clause 9.12.9. + +##### I.1.1.2 MIB upload + +When an ONU initializes, it populates its MIB with information about its equipment configuration and restores any other inbuilt information. The ONU makes this MIB visible to the OLT. MIB population should occur before the ONU responds to discovery messages, so that the response to an MIB upload request reflects the current configuration of the ONU. This permits the OLT to discover the hardware and service configuration of the ONU by analysing the uploaded MIB. + +## I.1.2 MIB data sync + +### I.1.2.1 MIB data sync attribute + +It is essential to the correct operation of the composite access system to keep the MIB synchronized between the OLT and ONU. The generic tool to achieve this is the MIB data sync attribute of the ONU data ME. The MIB data sync attribute is an 8 bit sequence number. When auditing the ONU's MIB, the OLT requests this sequence number. If the ONU's sequence number is equal to the sequence number in the OLT, the OLT may decide that no further action is needed, as the copy of the MIB in the ONU and the copy in the OLT are likely to be identical. However, the MIB data sync attribute does not reflect the state of the entire MIB, so it is important to understand its operation. + +### I.1.2.2 MIB data sync operation + +The MIB data sync attribute is incremented for the creation and deletion of ME instances that are the consequences of commands by the OLT. The MIB data sync counter is also incremented for changes in attribute values that are the consequences of commands by the OLT (Figure I.1.2.2-1). The MIB data sync counter is incremented once per executed command, not once per changed attribute. This includes the modification of the MIB data sync counter attribute itself via a set command from the OLT. Therefore, a set of the MIB data sync counter to the value $N$ results in an MIB data sync counter value of $N + 1$ after completion of the set command. + +A set action can include several attributes, some of which may result in changes to the ONU's MIB, and others which may fail. MIB sync is updated if and only if the ONU's MIB changes, i.e., if any of the attributes are modified. This rule is not intended to establish a policy on all-or-nothing transaction semantics, which is beyond the scope of this Recommendation. + +![Sequence diagram showing the increment of MIB data sync at the ONU and OLT under OLT command.](e7dab3b6aab892ac9aef3cfc6310d26c_img.jpg) + +``` +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: The ONU executes command, updates its MIB and increments MIB data sync. + OLT->>ONU: Command that changes the ONU's MIB (create, delete, set) + ONU-->>OLT: Command response (result-reason code) + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + Note center: MIBs in the OLT and ONU are aligned. + Note right of ONU: G.988(12)_FI.1.2.2-1 +``` + +The diagram illustrates the interaction between an OLT and an ONU. The OLT sends a 'Command that changes the ONU's MIB (create, delete, set)' to the ONU. The ONU responds with a 'Command response (result-reason code)'. During this process, the ONU updates its MIB and increments its MIB data sync. The OLT also updates its MIB and increments its MIB data sync. The final state is that the MIBs in the OLT and ONU are aligned. The diagram is labeled G.988(12)\_FI.1.2.2-1. + +Sequence diagram showing the increment of MIB data sync at the ONU and OLT under OLT command. + +**Figure I.1.2.2-1 – Increment of MIB data sync at the ONU and OLT under OLT command** + +In contrast, the MIB data sync counter is not incremented for autonomous creation and deletion of ME instances by the ONU itself, nor is the MIB data sync counter incremented for autonomous changes to attributes of MEs within the ONU (Figure I.1.2.2-2). + +![Sequence diagram showing an autonomous attribute value change at the ONU. The ONU updates its MIB and sends a notification to the OLT. The OLT updates its MIB, and the two are aligned. No increment of MIB data sync occurs at the ONU.](672a318767e4141941272424110be3b2_img.jpg) + +``` + +sequenceDiagram + participant ONU + participant OLT + Note right of ONU: Attribute value changes autonomously. +The ONU updates its MIB. + ONU->>OLT: Attribute value change notification + Note left of OLT: The OLT updates its MIB. The MIB in +the OLT and ONU are aligned. + Note right of OLT: G.988(12)_FI.1.2.2-2 + +``` + +Sequence diagram showing an autonomous attribute value change at the ONU. The ONU updates its MIB and sends a notification to the OLT. The OLT updates its MIB, and the two are aligned. No increment of MIB data sync occurs at the ONU. + +**Figure I.1.2.2-2 – No increment of MIB data sync at the ONU and OLT** + +If the ONU is offline when the OS sends a command (create/delete/set), the OLT updates its MIB locally and increments its MIB data sync, but it cannot send the command to the ONU. The incremented OLT MIB data sync value guarantees that when the ONU comes online, the MIB audit will fail. This mechanism also forces audit and reconciliation when an ONU is replaced. + +The order in which the OLT and the ONU update their MIBs and increment the MIB data sync attribute is not specified. Regardless of the order chosen, both the OLT and the ONU must locally update their MIBs and increment their MIB data syncs as atomic actions. It is considered good practice for the OLT not to increment its MIB data sync counter until it has received a positive AK to the command that it sent to the ONU. + +When incremented, the sequence number that follows 255 is 1. Zero is reserved for the following cases: + +- 1) default MIB with which the ONU left the factory; +- 2) an ONU which after initialization cannot restore its MIB. + +In other words, a sequence number of 0 indicates that the ONU's MIB is not well defined or that it does not contain service provisioning and therefore requires configuration or reconfiguration. + +### I.1.2.3 Loss of MIB synchronization + +In the process of an OLT modifying the MIB in an ONU, the MIB at the OLT could fall out of synchronization with the MIB at the ONU. Figure I.1.2.3-1 shows one possible scenario for this. + +![Sequence diagram showing a loss of MIB synchronization. The OLT sends a command to the ONU. The ONU executes the command and increments its MIB data sync. The OLT receives a success response but fails to update its MIB and does not increment its MIB data sync. The MIBs are not aligned.](7da136fbb50557a2d27c15b3bc7e4a66_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: Command that changes the ONU's MIB (create, delete, set) + OLT->>ONU: Command that changes the ONU's MIB (create, delete, set) + Note right of ONU: The ONU executes command, updates its +MIB and increments MIB data sync. + ONU->>OLT: Command response (success) + Note left of OLT: The OLT fails to update its MIB +and does not increment its +MIB data sync. + Note right of OLT: MIBs in the OLT and +ONU are not aligned. + Note right of OLT: G.988(12)_FI.1.2.3-1 + +``` + +Sequence diagram showing a loss of MIB synchronization. The OLT sends a command to the ONU. The ONU executes the command and increments its MIB data sync. The OLT receives a success response but fails to update its MIB and does not increment its MIB data sync. The MIBs are not aligned. + +**Figure I.1.2.3-1 – Mismatch of MIBs at the ONU and OLT under OLT command** + +Figure I.1.2.3-2 illustrates an autonomous change at the ONU, whose AVC is not received by the OLT. Normally, this information is transient and is not part of the MIB as strictly defined, but it must be recognized that the OLT no longer has a correct view of the ONU's current state. Periodic scans of ONU information are therefore encouraged. + +![Sequence diagram illustrating a lost AVC scenario between an OLT and an ONU. The ONU changes an attribute value and updates its state. The OLT sends a notification, but it is lost. The OLT does not have a correct view of the ONU state. The diagram is labeled G.988(12)_FI.1.2.3-2.](e3619747794d5b8133d31b12f9613949_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: An attribute value changes autonomously. +The ONU updates its state. + OLT->>ONU: Notification + Note left of OLT: Notification does not reach the OLT. +The OLT does not have a correct view of ONU state. + Note right of ONU: AVC [lost] + Note right of ONU: G.988(12)_FI.1.2.3-2 + +``` + +Sequence diagram illustrating a lost AVC scenario between an OLT and an ONU. The ONU changes an attribute value and updates its state. The OLT sends a notification, but it is lost. The OLT does not have a correct view of the ONU state. The diagram is labeled G.988(12)\_FI.1.2.3-2. + +**Figure I.1.2.3-2 – Lost AVC** + +### I.1.3 MIB audit and resynchronization + +#### I.1.3.1 MIB audit + +The ONU is audited with respect to its MIB in three cases: + +- 1) on loss and re-establishment of the OMCC; +- 2) periodically, based on the operator's requirements; +- 3) on demand of an OS. + +On detecting a newly installed ONU, regardless of the sequence number of its MIB, the OLT will directly perform an MIB reset and the new-ONU bring up procedure (clause I.1.4.1). Figure I.1.3.1-1 is the scenario diagram of an MIB audit that uncovers no problems. + +![Sequence diagram illustrating an MIB audit scenario. The OLT requests MIB data sync. The ONU responds with 'Get (ONU data (MIB data sync))'. The OLT compares the retrieved MIB data sync with its own copy. The values are the same: the OLT assumes the MIBs are aligned. The diagram is labeled G.988(12)_FI.1.3.1-1.](8757d7929b1f1d119dc172cea2f118e3_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT requests MIB data sync. + OLT->>ONU: Get (ONU data (MIB data sync)) + ONU-->>OLT: Get response + Note left of OLT: The OLT compares retrieved MIB data sync with its own copy. +The values are the same: the OLT assumes the MIBs are aligned. + Note right of ONU: G.988(12)_FI.1.3.1-1 + +``` + +Sequence diagram illustrating an MIB audit scenario. The OLT requests MIB data sync. The ONU responds with 'Get (ONU data (MIB data sync))'. The OLT compares the retrieved MIB data sync with its own copy. The values are the same: the OLT assumes the MIBs are aligned. The diagram is labeled G.988(12)\_FI.1.3.1-1. + +**Figure I.1.3.1-1 – MIB audit** + +#### I.1.3.2 MIB resynchronization + +Since the MIB data sync attribute does not reflect the status of the entire MIB, it is considered good practice for the OLT to periodically perform an MIB resynchronization regardless of the outcome of an MIB audit. The OLT may repair the MIB incrementally, as illustrated in Figure I.1.3.2-1, or it may choose to simply reset the MIB and rebuild it from scratch. + +![Sequence diagram illustrating MIB resynchronization between an OLT and an ONU. The process starts with the OLT requesting a MIB data sync. The ONU responds with 'Get (ONU data (MIB data sync))' and 'Get response'. The OLT compares the retrieved data with its own copy; if they don't match, it initiates a 'MIB upload'. The ONU makes a copy of its MIB and responds with the number of 'MIB upload next' commands required. The OLT then sends 'MIB upload next' requests and receives 'MIB upload next response' until all data is uploaded. Finally, the OLT compares the ONU's MIB with its local copy and issues 'Create, delete, set commands as needed' to the ONU. The diagram is labeled G.988(12)_FI.1.3.2-1.](1ea582f700d54c53aa8e2fb4d57602d6_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT requests MIB data sync. + OLT->>ONU: Get (ONU data (MIB data sync)) + ONU-->>OLT: Get response + Note left of OLT: The OLT compares retrieved MIB data sync with its own copy. The values do not match. + OLT->>ONU: MIB upload + Note right of ONU: The ONU makes a copy of its MIB and responds with an indication of the number of MIB upload next commands required. + ONU-->>OLT: Get response + OLT->>ONU: MIB upload next + ONU-->>OLT: MIB upload next response + Note left of OLT: The OLT uploads the MIB from the ONU. + Note right of OLT: ... + OLT->>ONU: MIB upload next + ONU-->>OLT: MIB upload next response + Note left of OLT: The OLT compares ONU's MIB with its own local copy and issues commands appropriately to bring the ONU MIB into alignment with its own. + OLT->>ONU: Create, delete, set commands as needed + +``` + +G.988(12)\_FI.1.3.2-1 + +Sequence diagram illustrating MIB resynchronization between an OLT and an ONU. The process starts with the OLT requesting a MIB data sync. The ONU responds with 'Get (ONU data (MIB data sync))' and 'Get response'. The OLT compares the retrieved data with its own copy; if they don't match, it initiates a 'MIB upload'. The ONU makes a copy of its MIB and responds with the number of 'MIB upload next' commands required. The OLT then sends 'MIB upload next' requests and receives 'MIB upload next response' until all data is uploaded. Finally, the OLT compares the ONU's MIB with its local copy and issues 'Create, delete, set commands as needed' to the ONU. The diagram is labeled G.988(12)\_FI.1.3.2-1. + +**Figure I.1.3.2-1 – MIB resynchronization** + +The OLT must issue as many MIB upload next requests as the number of commands given in the MIB upload response. The maximum time between two MIB upload next requests is 1 min. If the OLT does not send an MIB upload next request within this time after the previous MIB upload next request or after the MIB upload start request, the ONU assumes the MIB upload to be terminated. The ONU can drop its copy of the MIB, and consider any further MIB upload next requests to be invalid. + +MIB upload returns all attributes of most MEs, including those that reflect transient information. MIB upload is therefore a valid way for the OLT to synchronize much transient information, as well as data of long-term interest. However, certain MEs are excluded from the MIB upload. In particular, instances of some general purpose MEs, such as the ME and the attribute ME, are not included in an MIB upload. Table attributes are never included in an MIB upload. If the OLT requires this information, it obtains it on a per table basis through the use of the get/get next mechanism. And finally, the measurement attributes of PM MEs are not included in MIB uploads. + +As the final step of MIB resynchronization, the OLT sets the MIB data sync attribute of the ONU data ME to some suitable value of its own choice. It then sets its own record of the same attribute to the same value, incremented by 1, as explained in clause I.1.2.2. + +#### I.1.4 Bringing up ONUs + +ONU bring-up may be separated into two classes: new ONU bring-up and old ONU bring-up. The definition of new versus old ONU is based on the status of the ONU as viewed by the OLT. + +**New ONU:** The ONU has never completed MIB synchronization with the OLT. Some examples follow. + +- 1) The ONU has never been connected to the OLT, and the OLT has never recorded its serial number. This could arise during initial installation or replacement of an ONU. +- 2) The ONU has been connected to the OLT but the OLT did not assign a management layer ONU-ID to it. This could happen if an ONU is auto-discovered but has not been provisioned for service. + +NOTE – A TC layer ONU-ID is a precondition of successful transition into state O5. The TC layer ONU-ID is not necessarily the same as the management layer ONU-ID, nor is it necessarily stable from one activation lifetime to another. The management layer ONU-ID is the name by which an ONU is visible from a service and maintenance point of view, and normally persists for the lifetime of a service endpoint, even across the possible replacement of physical ONUs. + +- 3) The ONU has been provisioned but later de-provisioned by an OS. That is, its management layer ONU-ID has been de-assigned from the OLT. + +**Old ONU:** The ONU has been connected to the OLT, it has been assigned a management layer ONU-ID, and has completed MIB synchronization at least once. The OLT has a non-trivial MIB for this ONU and needs to confirm during bring-up that the ONU's MIB matches its own. + +#### I.1.4.1 Old ONU bring-up + +After the ONU powers up and begins execution of a valid software image, it automatically creates an MIB. Refer to the respective TC layer specification for a detailed explanation of state transitions during the activation process. + +Once the ONU enters operation state O5 after activation, the OLT creates the OMCC as described in clause B.1. As described in clause I.1.3.1, the OLT then retrieves the ONU MIB data sync value by sending a get (ONU data (MIB data sync)) message to the ONU. The OLT compares the received MIB data sync attribute value to the OLT's own MIB data sync value for that ONU. The result of the comparison leads to three possible ONU bring-up scenarios as follows. + +- If the ONU's MIB data sync value matches the OLT's value, and is not zero, the OLT may assume that their MIBs are in alignment. The ONU bring-up process is complete. + +NOTE – The OLT ultimately makes the choice between trusting MIB sync match – which is not a guarantee – and resynchronizing the MIBs in detail. The OLT also has the choice to reset the MIB and rebuild it from scratch or to audit and repair it incrementally. + +- If the ONU's MIB data sync value equals zero, possibly the result of an ONU software upgrade or because the ONU considers its MIB to be invalid, the OLT follows the bring-up sequence described for a new ONU (clause I.1.4.2). +- If the ONU's MIB data sync value does not match the OLT's value, the OLT executes the MIB synchronization process, as described in clause I.1.3.2. Once the OLT has provisioned the ONU's MIB, it must align MIB data sync values. The OLT completes the bring-up process by sending a set (ONU data (MIB data sync)) command. + +#### I.1.4.2 New ONU bring-up + +The bring-up process for a new ONU is shown in Figure I.1.4.2-1. Initially, the OLT sets the ONU MIB to its default state by sending an MIB reset to the ONU. The ONU re-initializes its MIB to the default and resets the MIB data sync attribute to zero. Next, the OLT uploads the ONU's MIB to retrieve all ME instances and capabilities. The OLT then issues create, delete and set commands to bring the ONU's MIB into sync with the OLT's MIB. + +NOTE – The details of initialization may differ in other (non-G-PON) access technologies. + +When an ONU changes an attribute value autonomously, it sends an AVC message to the OLT. The ONU can send AVCs during the MIB synchronization or MIB download processes. AVCs should be viewed as a partial method of ONU state discovery. Not all MEs or attributes issue AVCs, and an + +AVC message can be lost in transmission without an error being detected. Therefore, the OLT should audit the ONU state immediately after a reset has been completed. + +![Sequence diagram of New ONU bring-up process between OLT and New ONU.](acdd648e0d627e3683ae771309e97d5a_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant New ONU + + Note right of New ONU: Power up, select local software image, and create MIB + + Note left of OLT: Activation + OLT->>New ONU: Upstream_overhead PLOAM + Note right of New ONU: + OLT->>New ONU: Ranging_time PLOAM + Note right of New ONU: + OLT->>New ONU: Configure port_ID PLOAM + Note right of New ONU: + New ONU->>OLT: Acknowledge PLOAM + Note right of New ONU: + OLT->>New ONU: MIB reset + Note right of New ONU: Clear MIB, re-initialize to default + New ONU->>OLT: MIB reset response + Note right of New ONU: + Note right of New ONU: An attribute value changes autonomously, ONU updates MIB + New ONU->>OLT: Attribute value change notification + Note left of OLT: Notification reaches OLT; OLT updates its MIB + Note left of OLT: MIB reset + OLT->>New ONU: MIB upload, MIB upload next + Note right of New ONU: + New ONU->>OLT: MIB upload next response + Note left of OLT: Save retrieved ONU data + Note left of OLT: MIB provisioning + OLT->>New ONU: Command [create, delete, set] + Note right of New ONU: Execute command, update MIB and MIB data sync + New ONU->>OLT: Command response + Note left of OLT: Increment MIB data sync + Note right of New ONU: + Note right of New ONU: An attribute value changes autonomously, ONU updates MIB + New ONU->>OLT: Attribute value change notification + Note left of OLT: Notification reaches OLT; OLT updates its MIB + OLT->>New ONU: Set (ONU data (MIB data syncN)) + Note right of New ONU: ONU sets its MIB data sync to value N, then increments to N+1 + New ONU->>OLT: Set response + Note left of OLT: OLT sets its MIB data sync to value N+1 + +``` + +The sequence diagram illustrates the interaction between an OLT and a New ONU during the bring-up process. It is divided into three main phases: Activation, MIB reset, and MIB provisioning. + +1. **Activation:** The New ONU powers up and creates its MIB. The OLT sends Upstream\_overhead PLOAM, Ranging\_time PLOAM, and Configure port\_ID PLOAM messages. The ONU responds with Acknowledge PLOAM. + +2. **MIB reset:** The OLT sends a MIB reset message. The ONU clears its MIB and re-initializes to default, then responds with MIB reset response. An attribute value change notification is sent from the ONU to the OLT, which updates its MIB. The OLT then sends MIB upload, MIB upload next messages, and the ONU responds with MIB upload next response. The OLT saves the retrieved ONU data. + +3. **MIB provisioning:** The OLT sends a Command [create, delete, set] message. The ONU executes the command, updates its MIB, and sends a Command response. The OLT increments its MIB data sync. Another attribute value change notification is sent from the ONU to the OLT, which updates its MIB. The OLT sends a Set (ONU data (MIB data syncN)) message. The ONU sets its MIB data sync to value N and increments it to N+1, then responds with Set response. Finally, the OLT sets its MIB data sync to value N+1. + +The diagram also includes internal actions for both the OLT and the ONU, such as 'Notification reaches OLT; OLT updates its MIB' and 'An attribute value changes autonomously, ONU updates MIB'. + +Sequence diagram of New ONU bring-up process between OLT and New ONU. + +G.988(12)\_FI.14.2-1 + +Figure I.1.4.2-1 – New ONU bring-up + +## **I.2 Equipment management** + +### **I.2.1 Slot-port model** + +ONU equipment management is modelled on a three-level hierarchy: the chassis (the ONU itself), cardholders (also known as slots), which may contain circuit packs of varying types over the course of time, and ports, which present external interfaces either to the subscriber, to the PON or to a local management tool. Many OMCI MEs are addressed in accordance with the slot-port model. Ports – the PPTP group of MEs – would be expected to follow this model, but the T-CONT, MAC bridge service profile and traffic scheduler are also modelled by slot, if not by port. + +All ONUs must therefore adhere to at least a minimal slot-port model. An integrated ONU is represented as a virtual chassis containing virtual cardholders. There are three ways in which this may be done. + +- 1) Several virtual cardholders may be defined, one for each interface type. This was the original model and is the most common. The more significant byte of the ME ID of a virtual cardholder has the value 1; a real cardholder has the value 0. In both cases, the slot number (actual or virtual) is the value of the less significant byte. +- 2) A single virtual cardholder may be defined as slot 0 (LS byte), and all interfaces may be represented through the port-mapping package ME, which maps ports of arbitrary types in arbitrary combinations. The port-mapping package has the merit that it is universally applicable to integrated and chassis-based ONUs equipped with any type of real or virtual circuit pack, but for historical reasons, it is commonly used only when it is the only choice: a chassis-based ONU that contains circuit packs with mixed port types. +- 3) The port-mapping package may be contained by the ONU directly, rather than by a virtual cardholder. This approach has the merit that it avoids a virtual cardholder that serves no real purpose, and the disadvantage that it applies only to integrated ONUs. It is unlikely to appear in actual practice. + +In the original model, real or virtual slot numbering was segregated by PON-side (128 up) vs subscriber-side (127 down). Although this constraint is no longer specified – it was unsatisfactory for real chassis with real slots, as well as mixed-function circuit packs – some virtual-slot implementations continue to follow this convention for historical reasons. + +In addition, the two MSBs of the slot address are available to designate xDSL bearer channels when desired. While this violates orthogonality, it poses fewer problems in practice than in theory, since a space of 64 slots more than suffices for real or virtual cardholders. Best practice would indicate that slot numbers be unique within their 6 LSBs, particularly if there is any possibility that xDSL bearer channels may need to be modelled. + +As to port addressing, the original model specified ports numbered in increasing order, left to right, bottom to top, but this was inappropriate both for three-dimensional ONU packages with mixed ports of all types on several surfaces or edges and for chassis-based ONUs with service connections through the backplane rather than on circuit pack faceplates. Today, port addresses are expected only to start with 1 and to be unique. Small numbers in a contiguous sequence are preferred. + +Finally, it is worth mentioning that nothing actually prohibits mixing port types on any card type, without benefit of the port-mapping package. The combined video UNI and PON type (code point 44) even explicitly allows for differing port types. No convention exists for the numbering of such ports, configuration discovery is likely to be a problem and best practice would avoid this option. + +### **I.2.2 The chassis-based ONU** + +The original slot-port model was, and is, arguably adequate for integrated ONUs, where it is easy to create as many virtual cardholders as may be desirable. For chassis-based ONUs, however, a number of difficulties arise. + +- The model does not readily accommodate the richness of possible service interfaces. Table 9.1.5-1 defines circuit pack types, with an eye to listing all possibilities, but it does not scale well. As an example, the long list of VF specials is not presently represented. See also the next two list entries. +- The model does not adequately represent common equipment, circuit packs with no external ports at all, for example, power supply packs. This Recommendation includes a single code point for common equipment; it does not distinguish different types of common equipment. +- It has no way to flexibly model equipment with a combination of interfaces, e.g., a single circuit pack with a PON interface, a craft port and an RF video port (code point 44 includes PON and RF video, but not craft). Code point 45 is defined for multi-function packs; it does not distinguish different types of multi-function packs. As mentioned above, port numbering conventions are undefined, except by way of the port-mapping package. +- There were ambiguities in the original plug-in unit type definitions of [ITU-T G.984.4], specifically between the possible mixes of 10/100/1000 Mbit/s Ethernet and its physical media. The ambiguity was resolved with a compromise, but existing implementations must be regarded with caution. +- The original model could not distinguish between two Ethernet packs, e.g., with four ports on one and eight on the other. Port count attributes were added as a patch, but they do not address the reality that both operators and vendors are likely to manage real equipment inventory by a code (CLEI, for example, or vendor product name/number), rather than simply by generic type. + +The integrated ONU was first to be developed, so the issues aforementioned were not immediately apparent. Various extensions have been added to the equipment model to address these concerns, as discussed in the following. + +While the generic circuit pack types of Table 9.1.5-1 arguably suffice for the integrated ONU, it is recommended that the chassis-based ONU use the equipment ID attributes as its primary means to identify equipment options. Equipment ID is also the preferred way to identify an integrated ONU for inventory purposes. + +In Table 9.1.5-1, a small range of equipment types is reserved for vendor-specific assignment. Vendor-specific code points would seem to introduce interoperability issues, but they are in principle no worse than equipment ID as an identifier: the OLT and EMS must have *a priori* knowledge of the meaning and characteristics of whatever identifiers are used, presumably through business agreements and information exchange between the vendors concerned. + +## I.2.3 Dynamic behaviour + +### I.2.3.1 ONU initialization: the ONU's view + +When an ONU initializes, it populates its MIB with information about its equipment configuration. The Recommendations are written as if the ONU discovers this information for itself when it comes to life. This may be the case, but it is also possible that an ONU, especially an integrated ONU, may be equipped with a basic MIB at the factory, in which case initialization may comprise merely copying the MIB into a working store and discovering only options that may have changed after the last shutdown and prior to the current initialization. + +If it exists, the non-volatile MIB image used as the initialization reference for a chassis-based ONU may be populated with circuit pack types or equipment IDs, either by factory predetermination or from prior operation of the ONU. This equipment may or may not be present during the current initialization. Whether there is a non-volatile MIB or not, the ONU must actually perform some level of self-discovery to determine what, if anything, exists in its cardholders. + +The ONU is specified to issue AVCs or alarms when it discovers circuit packs or when it discovers that a circuit pack that was recorded in its non-volatile MIB (if there is one) is no longer present or no longer has the same type or equipment ID. However, it is recommended that ONU initialization occur before the ONU is activated on the PON, so transmission of AVCs and alarms is not possible. Queueing of notifications for future delivery is not specified, so the OLT must audit the connected equipment when the ONU re-ranges. + +If there are mismatches between an ONU's actual equipped configuration and its (possible) non-volatile MIB, the ONU should declare alarms as appropriate and should not attempt to bring the mismatched circuit packs into service. + +### **I.2.3.2 ONU initialization: the OLT view** + +When the OLT activates an ONU, the OLT either has an MIB that corresponds to that ONU or it does not. + +**If the OLT does not have an MIB** for that particular ONU already, it uploads the ONU's MIB as a starting point. Subsequent operation and provisioning is recorded both in the ONU's MIB and in the OLT's functional duplicate. AVCs from the ONU alert the OLT to changes that could occur from external causes such as craft removal or the installation of circuit packs. An AVC triggers the OLT to update its view of the ONU. The details of such an update are beyond the scope of this Recommendation. + +When it activates the ONU, the OLT may already have an MIB (or database functional equivalent) for a particular ONU, either because the ONU has been pre-provisioned or because the ONU has previously been active on the PON. The initialization requirements are the same in either case. + +**Assuming that the OLT has an MIB** for this particular ONU, an audit is necessary once activation is complete as part of service (re-)activation. The ONU is responsible for knowing its current equipment configuration, which must be reconciled by the OLT. The OLT, on the other hand, is responsible for knowing all provisioned information, and to ensure that, once initialization is complete, the ONU is provisioned accordingly. The OLT should declare alarms or events towards an EMS if the configuration has changed unexpectedly or provisioning reconciliation fails. + +### **I.2.3.3 Circuit pack provisioning** + +Clause I.2.3.2 discusses ONU initialization. This clause discusses the dynamics of circuit pack provisioning, installation and removal for an ONU that is active on the PON. It assumes a chassis-based ONU: changes to (virtual) circuit packs should not occur on integrated ONUs. An integrated ONU should deny attempts to provision cardholder and circuit pack attributes that are in fact immutable, even if their OMCI definitions indicate that they have write or set-by-create semantics. + +The ONU is sensitive to four events in this context, each of which has a number of use cases. Each event is discussed in clauses I.2.3.3.1 to I.2.3.3.4. + +- 1) A circuit pack is provisioned into a cardholder. +- 2) A cardholder is de-provisioned. +- 3) A circuit pack is physically inserted into a cardholder. +- 4) A circuit pack is physically extracted from a cardholder. + +#### **I.2.3.3.1 Circuit pack provisioned into a cardholder** + +This event comprises the change of any of the writable attributes of the cardholder, except setting the expected plug-in unit type to 0, which is covered in I.2.3.3.2. If the expected plug-in unit type is 0, all of the other attributes of the cardholder may be freely altered without generating a provisioning event or affecting the ONU's state or its alarms. That is, the ONU's expectation of the presence or absence of a circuit pack is based entirely on the non-zero value of the expected plug-in unit type attribute. + +**If the cardholder is empty at the time of provisioning**, the ONU can, and should, confirm that all attributes are consistent within the scope of its knowledge. That is, if either or both the expected port count and expected equipment ID are also provisioned, either in the same set command or separately, the combination of attributes must be consistent with the expected plug-in unit type. An Ethernet pack CLEI, for example, should be denied in the expected equipment ID attribute if the expected plug-in unit type is xDSL. Likewise, if the only Ethernet packs supported by the ONU have four ports, the ONU should deny an attempt to pre-provision an Ethernet slot with eight ports. Expected plug-in unit type code-point 255 (plug-and-play) is a "don't care" case in terms of consistency checking, but the remaining attributes must still be mutually consistent and known to the ONU. + +Assuming the provisioning event succeeds, the cardholder immediately declares the plug-in line interface module (LIM) missing alarm. If a standing alarm is undesirable, the alarm may be suppressed with an ARC. The ONU should then instantiate a circuit pack ME, though it may be only an empty husk if insufficient information is provided (plug-and-play case). + +It is possible that the provisioning command does not unambiguously define the equipment. For example, an ONU may support both a four-port and an eight-port Ethernet pack. If pre-provisioning merely calls out an Ethernet pack in such an example, best practice suggests that the ONU create an empty husk circuit pack ME. It is also acceptable for the ONU to deny the provisioning command, but creating four ports now and possibly four more ports later is discouraged. + +Given enough information about type, port count and equipment ID, the ONU now creates a fully populated circuit pack ME, along with a suitable number of PPTP or ANI-G MEs, and any other MEs known to be appropriate to the configuration, e.g., a port-mapping package ME, an equipment extension package or a protection data ME, software images, traffic shapers or T-CONTs. From this enhanced MIB, the ONU is prepared to accept pre-provisioning of services. Service pre-provisioning should be denied if an empty husk circuit pack ME was created. + +**If the cardholder is occupied at the time of provisioning**, the provisioning action may either create a mismatch with the existing circuit pack or resolve a mismatch. + +Provisioning creates a mismatch if it sets the expected plug-in unit type to any value other than 0, to 255 (plug-and-play) or to the actual type. Provisioning creates a mismatch if it sets the expected equipment ID to any value other than all spaces, or to the actual equipment ID. Provisioning creates a mismatch if it sets the expected port count to any value other than 0 or to the actual port count. The ONU declares an alarm for a type or equipment ID mismatch. No alarm is defined for expected port count mismatch; rather the ONU should deny a provisioning command that attempts to create such a mismatch. The ONU should take no additional action upon mismatch creation. For example, if service is in fact running on existing hardware, it should be left in place. (However, service would not be restored to a mismatch after ONU initialization, because the ONU would have no independent record of the prior configuration.) + +If the cardholder was in mismatch before the provisioning action, the mismatch is resolved if all of the following are true. + +- The expected plug-in unit type is provisioned to the actual plug-in unit type. If the ONU supports plug-and-play, code point 255 also resolves a mismatch. +- The expected port count is provisioned either to 0 or to the actual port count. +- The expected equipment ID is provisioned either to the actual equipment ID or to a string of all spaces. + +The ONU should clear any alarms that may have been declared as a consequence of the mismatch state. It should also initialize (or complete the initialization of) the physical circuit pack, up to and including bringing up any services that may be provisioned on to it. + +### I.2.3.3.2 Cardholder de-provisioned + +This event occurs when the cardholder's expected type is set to 0. If it was already 0, this is a no-op. The ONU should delete all associated MEs (see the list and foregoing examples), and clear any alarms associated with the equipment. It is an error for the OLT to de-provision equipment without first de-provisioning all services that depend on the equipment, and while ONU robustness is encouraged, the ONU's behaviour is undefined, up to and including the possibility that orphan or conflicting MEs may be left behind in the MIB, and nothing less than an MIB reset can recover. + +**If the cardholder is populated with a circuit pack at the time of de-provisioning**, the ONU should place it in an inactive holding pattern, awaiting extraction or re-provisioning. The holding pattern state implies no user services; provisioning and test commands should be denied, alarms should be cleared and no new ones generated, and ports and preferably the entire circuit pack should be powered down. ONU initialization from this state should initiate the sequence that occurs when a circuit pack is inserted into an unprovisioned slot. + +### I.2.3.3.3 Circuit pack physically inserted into a cardholder + +The two cases to consider in this event are distinguished by whether the circuit pack ME already exists. The common cases are the installation of new packs and the replacement of defective packs. In the normal course of events, a circuit pack ME exists before either of these events. + +**If the cardholder is provisioned with an expected plug-in unit type**, then a circuit pack ME exists, either of the specified type or of type 255, signifying unknown. When the actual circuit pack appears, the ONU updates the circuit pack ME with actual values from the equipment. If the appearance of the circuit pack resolves ambiguous provisioning, e.g., as a plug-and-play circuit pack, this is the point at which the ONU creates the subordinate MEs mentioned above: PPTPs, software images, etc. + +NOTE 1 – The OMCI does not define AVCs for changes to normally immutable attributes that may in fact change during this process. The OLT should use the AVC on the cardholder actual type and actual equipment ID to trigger a query of all cardholder and circuit pack attributes. + +The appearance of a circuit pack either triggers a mismatch, in accordance with the mismatch discussion above, or it does not. If there is no mismatch, the ONU continues initialization and bring-up of the circuit pack and services. If there is a mismatch, the ONU declares a mismatch alarm through the cardholder ME. No alarm is defined for a mismatch of port count. + +Most, if not all, PPTPs (ports) include an optional operational state ME. Among other circumstances, this attribute should have the value *disabled* when the pack is not present. Operational state should change to *enabled*, and be reported via an AVC, when the port successfully enters service. Within the scope of a current OMCI, the failure to receive an AVC on the port is the only notification the OLT has of port mismatch. + +**If the circuit pack ME does not already exist**, the ONU should instantiate it upon pack insertion. The ONU should populate the attributes of the circuit pack from the equipment itself, and report them to the OLT via AVCs from the cardholder. + +NOTE 2 – The OMCI does not define AVCs for changes to all attributes that may change during this process. The OLT should use the AVC on the cardholder actual type and actual equipment ID to trigger a query of all cardholder and circuit pack attributes. + +The ONU should instantiate the complete set of PPTP/ANI MEs, port.mapping packages, etc., as previously described. If the pack and ports pass self-test, each should report an AVC when its operational state becomes *enabled*. + +The absence of the circuit pack ME *a priori* guarantees that no additional pre-provisioned information exists in the MIB, except possibly in the de-provisioned corner case previously discussed, in which the ONU's behaviour is undefined. + +#### **I.2.3.3.4 Circuit pack physically extracted from a cardholder** + +The most common cause of this event is the replacement of a defective circuit pack. When the old circuit pack is extracted, the event may trigger additional alarms – the circuit pack and some or all of the services are likely already in alarm – such as cardholder improper removal. No MEs are deleted as the consequence of this event; MEs are only destroyed through de-provisioning. + +Replacing the defective pack with a like pack follows the normal sequence of events: the pack is initialized, no MIB changes are necessary and services are restored. Replacing the pack with an incompatible pack triggers mismatch behaviour as described in I.2.3.3.3. Replacing the pack with a functionally similar pack (e.g., different CLEI, same capabilities) may or may not be accepted by the ONU, depending on its built-in knowledge of equipment compatibilities. + +Less common is the removal of a circuit pack, either to leave the slot unpopulated or to reuse it for other purposes. It is recommended that services first be de-provisioned and then the cardholder be de-provisioned before the circuit pack is extracted, but if the pack is extracted first, it is treated exactly as if it were simply being replaced with another pack of the same type. + +#### **I.2.3.4 MIB sanity** + +Regardless of the flows previously described, it is always allowed and encouraged for an ONU to deny provisioning actions that create MIB inconsistencies. + +### **I.2.4 Protection** + +Two kinds of protection can be supported within the OMCI model: ANI (PON) protection; and equipment protection. Vendor-interoperable protection has not been widely deployed as yet; in the absence of real-world experience, some aspects of its operation doubtless remain for further study. + +The model for PON protection assumes two ANI MEs, which would presumably reside on separate circuit packs. The protection data ME coordinates the two ANIs and specifies various attributes of the protection group. PON protection handshaking is based on SDH K bytes. If more than LOS-based single-ended protection were to be supported, further work would likely be needed to rationalize the details of K-byte protection with G-PON. + +The model for equipment protection is exemplified by a chassis-based ONU with DS1 circuit packs, in which one or two circuit packs protect up to eight working packs. Protection of this nature is likely to be built into the backplane or cabling of the ONU; protection packs may or may not be the same as the working packs. This function is supported by the equipment protection profile ME. Equipment protection can be manually invoked through an attribute of the working cardholder ME. + +Subscriber facility protection, for example 1 + 1 protection of 155 Mbit/s drops, is not presently supported by the OMCI. + +### **I.2.5 Environmental inputs and outputs** + +The OMCI provides an equipment extension package that may be associated either with an ONU or a cardholder to provide external sense or control points. The conceptual model is of equipment able to detect external contact closures, and report either a closed or an open contact as an off-normal event. Rectifier plant alarms may be reported with this mechanism, for example. The semantics of these alarms are undefined to the OMCI and the ONU, and must be interpreted at the OLT or EMS level. + +Where the ONU structure is hard-wired for particular alarms that are already defined in the OMCI, the hard-wired alarms should be reported in preference to the general-purpose capabilities of the equipment extension package. For example, a physical intrusion alarm can be declared by the ONU-G, and is preferred, as long as no ONU provisioning is needed to associate the alarm with a specific input point. Likewise, existing battery alarms, declared by the ONU-G ME, are preferred where they convey the correct semantics and require no provisioning. + +The equipment extension package ME also allows for external control points to be activated or released. + +## **I.2.6 Managed entity analysis** + +This clause discusses MEs and attributes of interest. It is not a complete list of all concerned MEs or their characteristics; it represents those for which commentary is appropriate. + +### **I.2.6.1 ONU-G, ONU2-G** + +These MEs define attributes, actions and notifications that conceptually pertain to the ONU as a whole equipment unit. When the ONU is implemented as integrated equipment, no issues arise. This clause describes the common attributes, actions and notifications for the chassis-based ONU. + +#### **Attributes** + +Vendor ID, version, serial number, vendor product code (RO) – These attributes may not exist for the chassis *per se*. Their values may be taken from a controller pack, and may require re-provisioning or re-learning if a controller pack is replaced. + +Traffic management option (RO) – Report the value from the pack that implements traffic management. In most cases, this would be the controller pack. + +Battery backup [read, write (RW)] – The integrated ONU should proxy this value on behalf of the pack that implements battery monitoring unless explicit provisioning is required, in which case the external sense points of the equipment extension ME should be used instead. If the ONU/ONU has no capability to monitor battery-related states, it should deny an attempt to enable battery monitoring. + +Admin state (RW) – Administrative lock at the ONU level should disable all subscriber services on all ports of all circuit packs, and suppress all alarms, as well as powering down as much as possible, consistent with continued craft and PON access. + +Operational state (RO) – Operational state indicates whether the ONU in its entirety is capable of performing some (vs none) of its functions. In accordance with the state model of [ITU-T X.731], the ONU should report its operational state as *disabled* only if all of its ports are out of service for autonomous reasons (e.g., failure or circuit pack extraction). At the ONU level, this information is not very useful because operational state is an optional attribute, it may be omitted. + +Equipment ID (RO) – The equipment ID string is 20 characters, typically long enough for two informative fields. It is recommended that the primary information field be left justified in the equipment ID attribute, e.g., a CLEI code in markets that use this identifier. If a second identifier (e.g., vendor product designator) is desired, it is recommended that it be right-justified in the equipment ID attribute, with spaces padding the gap in the centre. Although this information may be provided by the controller pack rather than the backplane, it is quite likely to differ from the corresponding equipment ID attribute of the controller circuit pack, since it represents the ONU, rather than the circuit pack. + +OMCC version (RO) – This attribute indicates the OMCI version supported by the ONU as an entirety, and should be reported as the most primitive version, considering all software residing on all circuit packs. + +NOTE – For historical reasons, an implementation may report 0x80, even though it actually supports a more recent version of the OMCI. + +Total priority queue number, total traffic scheduler number (RO) – These attributes are defined to be the count of queues (schedulers) not associated with a specific circuit pack. The chassis-based ONU should report these on behalf of the controller (or traffic management) circuit pack, if a specific pack provides these functions. It is also acceptable to report these values as 0, and to report values for individual packs instead. + +Total GEM port-ID number (RO) – This attribute should be reported for the ONU as an entirety on behalf of the ANI or traffic management circuit pack, typically the (primary) controller. + +### Actions + +Reboot – This action should cause the ONU as an entirety to re-boot. It would be expected that the controller pack (or both controller packs) would re-boot, and any other circuit packs would be re-booted or re-initialized as applicable. Re-boot is not expected to be hitless to subscriber services. POTS calls are allowed to be dropped, and layers 2, 3 and 4 data associations are allowed to be lost. + +Test – The test action on a chassis-based ONU may not be meaningful. If the test action is not meaningful, it is the vendor's choice whether to reject an ONU-directed test action, or whether to proxy the action to the (primary) controller pack. + +Synchronize time – This action should resynchronize all circuit packs that maintain PM-related interval timers and counters. + +### Notifications – AVCs + +Op state – As previously noted, the operational state attribute is optional, and conveys little information at best. When the ONU is really incapable of performing any of its functions, it is likely also to be incapable of conveying a state indication over the PON. + +### Notifications – alarms + +Equipment alarm, ONU self-test fail – This alarm would be expected to be declared against an individual circuit pack, rather than against a chassis-based ONU as an entirety. If one of these alarms is declared by a chassis-based ONU, the alarm should really indicate a chassis-wide problem, not a circuit pack problem. + +Powering alarm, battery missing, battery failure, battery low, physical intrusion, voltage yellow, voltage red – These alarms are meaningfully declared by the ONU as entities in their own right. + +Dying gasp – The purpose of this alarm is to help the OLT distinguish, when possible, between fibre cuts and equipment faults. Dying gasp should therefore be declared by the ONU on behalf of the circuit pack that supports the ANI. That is, other parts of the ONU may remain up and running; the alarm indicates only the state of the PON optics, or of the ONU as an entirety. If the ONU has redundant PON interface circuit packs, dying gasp should not be declared to indicate failure, loss of power or imminent shutdown of one controller. In that sense, the alarm is really declared by the PON circuit pack, but using the ONU-G as a reporting entity. Dying gasp is not an irrevocable commitment to drop off the PON: the OLT should accept the possibility that the ONU remains active on the PON and clears the alarm after a last-second recovery. + +Temperature yellow, temperature red – While it is possible that a chassis could contain global temperature sensors, it is expected that, in the case of a chassis-based ONU, temperature alarms would be declared by individual circuit packs instead. In any event, the alarms should be declared by the ME that best represents the scope of the problem. + +ONU manual power off – This alarm is similar to dying gasp, inasmuch as it signals the likelihood that the ONU will drop off the PON, but it conveys the additional information that the shutdown is due to subscriber action. + +### I.2.6.2 Cardholder + +The cardholder ME is needed even by integrated ONUs because it contains information pertinent to the virtual slot model. + +## Attributes + +Actual plug-in unit type (RO) – This attribute takes a value from Table 9.1.5-1. Choices from the table are expected to suffice for the integrated ONU, and the equipment ID attributes are not expected to be used. + +Expected plug-in unit type (RW) – This attribute permits some level of pre-provisioning. Although the equipment ID is preferred to indicate a precise circuit pack type, this attribute should be selected from Table 9.1.5-1 to be as meaningful as possible. Even though this attribute is marked RW, the integrated ONU should deny attempts to change its value. + +Expected port count (RW) – This attribute permits pre-provisioning of generic circuit pack types when the equipment ID is not specified. Since equipment ID is preferred, this attribute should not be used. If it is used, it must be set to a value that does not conflict with other attributes, such as equipment ID, that may exist already or that may be part of the same set operation. As with the expected plug-in type, which is also RW, an integrated ONU should deny an attempt to change the value of this attribute. + +Expected equipment ID (RW) – The OMCI definition states that this attribute pertains only to real (not virtual) cardholders. An integrated ONU should deny an attempt to write its value. As noted earlier, vendors may choose to encode two informative fields into this attribute, e.g., a CLEI and a vendor product code name. No substring matching behaviour is expected: the provisioned value of this attribute must match exactly the value found in the equipment itself. + +Actual equipment ID (RO) – The OMCI definition states that this attribute pertains only to real (not virtual) cardholders. + +ARC and ARC interval (RW) – These attributes permit alarms to be suppressed on cardholders. The specific application is automatic in-service provisioning, whereby no alarms are declared on pre-provisioned empty slots, but upon insertion of the circuit packs, alarm behaviour goes to normal without further intervention from an OS. + +## Notifications – AVCs + +Actual type, actual equipment ID – These AVCs are not meaningful for integrated ONUs. + +## Notifications – alarms + +Plug-in circuit pack missing, plug-in type mismatch, improper card removal, plug-in equipment ID mismatch, protection switch – These alarms are not meaningful for integrated ONUs. + +### 1.2.6.3 Circuit pack + +VC packs exist for an integrated ONU. The type and number of port attributes are meaningful from an equipment management point of view. + +## Attributes + +Type (RWSC) – This attribute takes a value from Table 9.1.5-1. While the attribute value should align as closely as possible with an appropriate equipment type (Table 9.1.5-1), a chassis-based ONU should rely on the equipment ID attribute to convey precise information about circuit pack type. + +Number of ports (RO) – Because a circuit pack can have only one type, all of its ports must be the same, and this attribute is just a scalar port count. More complex configurations are managed either by defining additional virtual cardholders and VC packs (integrated ONU) or with the port-mapping package ME. + +Serial number, version, vendor ID, equipment ID (RO) – These attributes are reported from the circuit pack hardware. For the (primary) controller pack, they would have the same value as reported in the ONU-G ME pair. + +Administrative state (RWSC) – When this attribute has the value locked, all subscriber (and craft) services depending on this circuit pack are blocked. It may not be meaningful to lock circuit packs without subscriber (or craft) interfaces, or circuit packs with mixed interfaces such as ANI, LCT and video UNI; the behaviour in such a case depends on the vendor. It would be reasonable for the ONU to deny the lock operation, or for the operation to have no effect. It is desirable to power down as much circuitry as possible, and to minimize power consumption by establishing locked as the default state. + +Operational state (RO) – This attribute has the value disabled if none of the circuit pack's functions is operational for autonomous reasons. + +Power shed override (RW) – This attribute permits ports to be declared essential and thereby to be excluded from power-shedding timeout. It assumes a simple scalar numbering of ports, not to exceed 32. + +## **Actions** + +Reboot – This action is intended to permit an individual (real) circuit pack to be re-booted. If the circuit pack is the (primary) controller, however, it may have the same effect as an ONU reboot action. + +## **Notifications – alarms** + +Powering alarm – This alarm is intended to indicate a more specific failure of the equipment. The failed equipment could be either a power supply circuit pack or a client circuit pack with a failed input fuse or converter. Battery and AC alarms are declared at the ONU level if they are hard-wired. + +### **1.2.7 Power shedding** + +Power shedding is the ability of an ONU to reduce power consumption during AC power outages. It is predicated on the assumption that the ONU is attached to a power source that contains a battery back-up and the ability to notify the ONU of AC power loss and restoration. When the ONU is notified by the power source that AC power has been lost, the ONU may reduce power consumption by shutting down selected ONU interfaces. For the purposes of provisioning, these interfaces are divided into classes that may be individually provisioned to shed power after AC power loss is reported to the ONU. + +Provisioning of ONU power shedding is accomplished through the use of two OMCI MEs. These are the ONU power-shedding ME and the circuit pack ME. The ONU power-shedding ME contains most of the attributes associated with power shedding. The circuit pack ME contains a single attribute, power shed override, that allows for the override of power shedding on a per port basis. + +The power-shedding ME is auto-created by an ONU if that ONU supports power shedding. + +The power shed override attribute within the circuit pack ME is a bit map that can be used on a per port basis to override the settings contained in the ONU power-shedding ME. This attribute is defined as a 4 byte bit map with port 1 as MSB. When a bit in this attribute is set to 1, the corresponding port in its circuit pack is exempt from the ONU power-shedding ME. + +If the hardware associated with the circuit pack does not support individually powering off its ports, then the entire attribute is taken as a single composite value. In this case, any bit of value 1 exempts all ports on that circuit pack from the ONU power-shedding ME. Intermediate cases are also possible, e.g., where the hardware permits ports to be powered down in groups of four. The point is to retain power on ports designated as essential, while powering down all other ports within the capabilities of the hardware. + +Of particular interest in the management of ONU power shedding is the expected behaviour of the ONU during various power-shedding scenarios. This is especially true for the relationship between the two timers represented by the attributes restore power reset interval ( $T_r$ ) and shedding interval ( $T_s$ ). This behaviour is depicted in Figure I.2.7-1, in which the following terms are used. + +- Start timer – The timer is started or resumed from its existing value. A start timer action does not imply a reset of the timer. +- Stop timer – The specified timer is stopped and not reset. +- Reset timer – Stops and resets a timer. The timer is not started. + +![Figure I.2.7-1 – Power-shedding state diagram. The diagram shows four states: AC on, PreShed timing, PostShed timing, and Power Shed. Transitions are triggered by AC on/off events and timer expirations. From AC on, an AC off event starts timer Ts, leading to PreShed timing. From PreShed timing, an AC on event stops timer Ts and starts timer Tr, leading to PostShed timing. From PostShed timing, an AC off event stops timer Tr and starts timer Ts, leading back to PreShed timing. From PreShed timing, if timer Ts expires, the system enters Power Shed, resetting timer Tr. From Power Shed, an AC on event starts timer Tr, leading to PostShed timing. From PostShed timing, if timer Tr expires, the system returns to AC on, resetting timer Ts.](708690b9d4762d58eaf12c1a5f225c23_img.jpg) + +``` + +stateDiagram-v2 + [*] --> AC_on : AC on + AC_on --> PreShed_timing : AC off, Start timer Ts + PreShed_timing --> AC_on : AC on, Stop timer Ts, Start timer Tr + PreShed_timing --> PostShed_timing : Stop timer Tr, Start timer Ts + PostShed_timing --> PreShed_timing : AC off, Stop timer Tr, Start timer Ts + PostShed_timing --> AC_on : Timer Tr expires, Reset timer Ts + PreShed_timing --> Power_Shed : Timer Ts expires, Reset timer Tr, Shed power + Power_Shed --> PostShed_timing : AC on, Start timer Tr + +``` + +Figure I.2.7-1 – Power-shedding state diagram. The diagram shows four states: AC on, PreShed timing, PostShed timing, and Power Shed. Transitions are triggered by AC on/off events and timer expirations. From AC on, an AC off event starts timer Ts, leading to PreShed timing. From PreShed timing, an AC on event stops timer Ts and starts timer Tr, leading to PostShed timing. From PostShed timing, an AC off event stops timer Tr and starts timer Ts, leading back to PreShed timing. From PreShed timing, if timer Ts expires, the system enters Power Shed, resetting timer Tr. From Power Shed, an AC on event starts timer Tr, leading to PostShed timing. From PostShed timing, if timer Tr expires, the system returns to AC on, resetting timer Ts. + +G.988(12)\_FI.2.7-1 + +Figure I.2.7-1 – Power-shedding state diagram + +## I.2.8 Remote debug + +The remote debug ME (clause 9.1.12) is used for free-form information exchange with an ONU for the purpose of debugging an ONU from an OLT. This may be appropriate due to the lack of other debug access (primarily due to security concerns of the operator) or because the ONU is located remotely. It is not the purpose of remote debug access to offer management abilities that should be done using conventional OMCI or other vendor-specific MEs. + +The remote debug entity has the ability to send 25 bytes of information to an ONU and collect up to 0xFFFFFE bytes of response. The information exchange may be ASCII coded or in vendor-specific binary format. + +It is assumed that the majority of the OLTs and ONUs would implement the ASCII format, whereby OLTs could inject basic ASCII commands to an ONU and receive ASCII formatted reports in reply. The raw binary data format offers the ability to collect information in a single-vendor environment for advanced debugging purposes. + +The ME ID of this object is always zero. Since the object is created by the ONU, no other ME IDs are possible. The remote debug capability of an ONU can be detected by a get operation on the remote debug ME, with an error response if the object does not exist. + +Command syntax (in either mode) is vendor-specific, as is the reply information. However, some general guidelines for the ASCII mode are suggested as best practice. The ASCII command *help* should be supported by the ONU, such that the ONU would then reply back with the available commands that may be supported by the remote debug process. In addition, if a command is not + +recognized or cannot be parsed by the ONU, a reply to that nature should be returned in the specified format. The use of OMCI error codes to indicate an error in the ASCII command (not the OMCI command) is not advised. + +Figure I.2.8-1 illustrates a potential remote debug exchange. In this example, the OLT sends an ASCII text string command *dump status* to the ONU, and the ONU replies. + +![Sequence diagram showing a remote debug exchange between an OLT and an ONU. The OLT sends a 'Get (ONU remote debug (command format))' message to the ONU, which responds with 'Get response (command format = ASCII)'. The OLT then sends 'Set (ONU remote debug (command = "dump status"))', and the ONU responds with 'Set response'. Next, the OLT sends 'Get (ONU remote debug (reply table))', and the ONU responds with 'Get response (reply table size)'. Finally, the OLT sends 'Get next (ONU remote debug (reply table, sequence))', and the ONU responds with 'Get next response'. The sequence ends with an ellipsis and the reference G.988(12)_FI.2.8-1.](6126a2dbd4b0734bf37397c068bd880f_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note right of ONU: G.988(12)_FI.2.8-1 + OLT->>ONU: Get (ONU remote debug (command format)) + ONU-->>OLT: Get response (command format = ASCII) + OLT->>ONU: Set (ONU remote debug (command = "dump status")) + ONU-->>OLT: Set response + OLT->>ONU: Get (ONU remote debug (reply table)) + ONU-->>OLT: Get response (reply table size) + OLT->>ONU: Get next (ONU remote debug (reply table, sequence)) + ONU-->>OLT: Get next response + Note left of OLT: ... + +``` + +Sequence diagram showing a remote debug exchange between an OLT and an ONU. The OLT sends a 'Get (ONU remote debug (command format))' message to the ONU, which responds with 'Get response (command format = ASCII)'. The OLT then sends 'Set (ONU remote debug (command = "dump status"))', and the ONU responds with 'Set response'. Next, the OLT sends 'Get (ONU remote debug (reply table))', and the ONU responds with 'Get response (reply table size)'. Finally, the OLT sends 'Get next (ONU remote debug (reply table, sequence))', and the ONU responds with 'Get next response'. The sequence ends with an ellipsis and the reference G.988(12)\_FI.2.8-1. + +**Figure I.2.8-1 – Success example** + +### I.3 Software upgrade + +#### I.3.1 Overview + +The software image ME is defined in clause 9.1.4. For each ME that contains independently manageable software (either the ONU or a circuit pack), the ONU creates two software images, 0 and 1. Each image has three Boolean attributes: committed; active; and valid. An image is valid if the contents have been verified to be an executable code image. An image is committed if it is loaded and executed upon reboot of the ONU or circuit pack. An image is active if it is currently loaded and executing in the ONU or circuit pack. At any given time, at most one image may be active and at most one image may be committed. + +An ONU goes through a series of states to download and activate a software image as shown in Figure I.3.1-1. Each state is determined by the status of both software images. For example, S3 is the state where both images are valid but only image 0 is committed and active. State S0 is a conceptual initialization state. + +The OLT controls the state of the ONU through a series of commands defined in clause 9.1.4. For example, an ONU in state S3 will traverse to state S4 upon receipt of the *activate(1)* command. The defined commands are *start download*, *download section*, *end download*, *activate image* and *commit image*. + +![Software image state diagram showing states S0 through S4 and S0' through S4'. Each state is a table with columns for SW image 0 and SW image 1, detailing their active, committed, valid, and version status. Transitions are labeled with commands like Reboot, Activate, Commit, Start download, End download, and Download section, often with numerical arguments (0 or 1). State S0 is marked as 'OMCC not operational'.](16fcd4fa5a01a7016b528f4dfad779cb_img.jpg) + +The diagram illustrates the state transitions for software images 0 and 1. States are represented as tables with the following structure: + +| State | SW image 0 | SW image 1 | +|---------------------------|-----------------------------------------------------------------------|-----------------------------------------------------------------------| +| S0 (OMCC not operational) | | | +| S1 | is active: yes
is committed: yes
is valid: yes
version: xxxx | is active: no
is committed: no
is valid: no
version: null | +| S1' | is active: no
is committed: no
is valid: no
version: null | is active: yes
is committed: yes
is valid: yes
version: yyyy | +| S2 | is active: yes
is committed: yes
is valid: yes
version: xxxx | is active: no
is committed: no
is valid: no
version: null | +| S2' | is active: no
is committed: no
is valid: no
version: null | is active: yes
is committed: yes
is valid: yes
version: yyyy | +| S3 | is active: yes
is committed: yes
is valid: yes
version: xxxx | is active: no
is committed: no
is valid: yes
version: yyyy | +| S3' | is active: no
is committed: no
is valid: yes
version: xxxx | is active: yes
is committed: yes
is valid: yes
version: yyyy | +| S4 | is active: no
is committed: yes
is valid: yes
version: xxxx | is active: yes
is committed: no
is valid: yes
version: yyyy | +| S4' | is active: yes
is committed: no
is valid: yes
version: xxxx | is active: no
is committed: yes
is valid: yes
version: yyyy | + +Key transitions include: + +- S1 to S1' via 'Reboot, Activate (1), Commit (1)'. +- S1' to S1 via 'Reboot, Activate (0), Commit (0)'. +- S1 to S2 via 'Start download (1)'. +- S2 to S1 via 'Reboot, End download (1), incorrect CRC'. +- S2 to S3 via 'End download (1), correct CRC'. +- S3 to S2 via 'Start download (1)'. +- S2' to S1' via 'Start download (0)'. +- S1' to S2' via 'Reboot, End download (0), incorrect CRC'. +- S2' to S3' via 'End download (0)'. +- S3' to S2' via 'Start download (0)'. +- S3 to S4 via 'Activate (1)'. +- S4 to S3 via 'Reboot, Activate (0)'. +- S3' to S4' via 'Activate (0)'. +- S4' to S3' via 'Reboot, Activate (1)'. +- S3 to S4' via 'Commit (1)'. +- S4 to S3' via 'Commit (1)'. +- S3' to S4 via 'Commit (0)'. +- S4' to S3 via 'Commit (0)'. +- S0 to S1 via 'Successful completion of initial (proprietary) bootstrap of SW image 0'. +- S0 to S1' via 'Successful completion of initial (proprietary) bootstrap of SW image 1'. + +Software image state diagram showing states S0 through S4 and S0' through S4'. Each state is a table with columns for SW image 0 and SW image 1, detailing their active, committed, valid, and version status. Transitions are labeled with commands like Reboot, Activate, Commit, Start download, End download, and Download section, often with numerical arguments (0 or 1). State S0 is marked as 'OMCC not operational'. + +G.988(12)\_Fl.3.1-1 + +NOTE – In Figure I.3.1-1, states S1 and S2 (and S1' and S2') are distinguished only for convenience in understanding the flow. Upon receipt of a start download message, and particularly when the ONU re-boots, any partial downloads in progress are discarded. + +Figure I.3.1-1 – Software image state diagram + +### I.3.2 Software image download + +The software image download operation is a file transfer from the OLT to the ONU. The OMCI defines two mechanisms to download software images to ONUs. This clause describes the mechanism built into the OMCI, first describing download in the context of the baseline OMCI message set; the description is then modified as appropriate for the extended message set. + +The second download mechanism uses the OMCI to define the parameters of a file transfer from an external server, which may or may not be the OLT. The file transfer controller is defined in clause 9.12.13, and is not discussed further in this clause. + +**I.3.2.1 Baseline message set download** The atomic unit of file transfer is the section, the 31 bytes of data that can be transferred in a single (baseline) download section message. The last section in a software download may be padded with null bytes as needed. + +A number of sections comprise a so-called window. A window may not exceed 256 sections. Figure I.3.2.1-1 illustrates the relationship between a software image and its decomposition into windows and sections. + +![Diagram illustrating the relationship between image, windows, and sections. The top row shows 'Section byte number' from 0 to 30. The middle row shows 'Window "Download section number"' from 0 to Window size-1. The bottom row shows 'Image'. Lines connect the sections to the windows and the windows to the image.](d43f2d108754e2ff9ca54f2deb9fb8be_img.jpg) + +The diagram illustrates the hierarchical decomposition of a software image. At the top, a row of 31 boxes represents 'Section byte number', with the first three labeled 0, 1, 2 and the last one labeled 30. A bracket under this row points down to a middle row of boxes representing 'Window "Download section number"'. The first three are labeled 0, 1, 2 and the last one is labeled 'Window size-1'. A bracket under this row points down to a bottom row of boxes representing the 'Image'. Lines connect groups of sections to individual windows, and windows to the overall image. + +Diagram illustrating the relationship between image, windows, and sections. The top row shows 'Section byte number' from 0 to 30. The middle row shows 'Window "Download section number"' from 0 to Window size-1. The bottom row shows 'Image'. Lines connect the sections to the windows and the windows to the image. + +G.988(12)\_FI.3.2.1-1 + +**Figure I.3.2.1-1 – Relationship between image, windows and sections (baseline message set)** + +During the initial software download message exchange, the OLT proposes a maximum window size, but a lower value can be stipulated by the ONU, which must be accepted by the OLT. The OLT may send windows with fewer sections than this negotiated maximum, but may not exceed the maximum. Though it is not a preferred choice, the OLT may send all windows at the full negotiated maximum size, with the final window of the download operation padded out with download section messages containing only null pad bytes. + +Each download section message contains a sequence number, which begins anew at 0 with each window. By tracking the incrementing sequence numbers, the ONU can confirm that it has in fact received each section of code. + +In the MT field of the last download section message of each window, the OLT indicates the end of the window by setting the AR (acknowledgement request) bit – prior download section messages are unacknowledged. If the ONU has not received the entire window correctly, i.e., if it misses a sequence number, it acknowledges with a command processing error result, whereupon the OLT falls back to the beginning of the window and tries again. To improve the chance of successful transmission, the OLT may choose to reduce the size of the window on its next attempt. + +When the final window has been successfully downloaded, the OLT sends an end software download message whose contents include the size of the downloaded image in bytes, along with a CRC-32 computed according to [ITU-T I.363.5], across the entire image but excluding pad bytes that may have been transmitted. If the ONU agrees with both of these values, it updates the software image + +validity attribute to indicate that the newly downloaded image is valid. Figure I.3.2.1-2 illustrates this process. + +The negotiation of the window size is governed by two opposing criteria: 1) maximize throughput and 2) avoid ONU receive buffer overflow. A problem arises if the ONU supports both baseline message set and extended message set. At the time when the ONU negotiates the window size, the ONU does not know whether the OLT will use baseline or extended message set for the download. If the ONU assumes the OLT will use extended message set for software download but the OLT actually uses baseline message set, then the ONU will choose a small window size and the throughput could be low. If the ONU assumes the OLT will use baseline message set for software download but the OLT actually uses extended message set, then the ONU will choose a large window size and the ONU receive buffer could overflow. + +Although ITU-T G.989.3 allows the OLT to switch between baseline and extended message set on subsequent messages, the following OLT behaviour is recommended (not mandatory) to prevent the resource constrained ONU from overflowing OR negotiating a low throughput: + +- If the OLT uses baseline "Start Download" message then all subsequent "Download segment" messages should also use baseline message format. Likewise if the OLT uses extended "Start Download" message then all subsequent "Download segment" message should also uses extended message format. The ONU can respond with an appropriate window size based on the knowledge of the message set the OLT intends to use based on the "Download segment" message +- If the OLT supports OLT-G ME, the ONU can derive the OLT use of baseline or extended message set in software download based on a priori knowledge of the vendor/equipment information. + +![Sequence diagram of the software download process between an OLT and an ONU. The process involves a start message, window size negotiation, section-by-section download with acknowledgments, a retransmission for a failed window, and a final end download message.](c51726be9e547fe7702158a6a10a88a8_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + + Note right of ONU: The ONU sets given software image ME to not valid +The ONU updates MIB data sync. +The ONU responds with the same or smaller window size N. + + OLT->>ONU: Start software download (instance, window size-1, image size[, parallel download info]) + ONU-->>OLT: Start software download response (instance, success, window size-1[, parallel download info]) + + Note left of OLT: The OLT accepts proposed window size N. +The OLT updates the MIB and increments MIB data sync. +The OLT downloads the first window: for illustration, +this one contains N full sections. + + OLT->>ONU: Download section (instance, section 0, 31 bytes of image data) + OLT->>ONU: Download section (instance, section 1, 31 bytes of image data) + Note right of OLT: ... + OLT->>ONU: Download section (instance, section N-1, 31 bytes of image data) [AR = ack rqst] + ONU-->>OLT: Download section response (instance, command processing error, section N-1) + + Note left of OLT: ONU signals failure to receive some or all of window. +The OLT re-transmits the window. For illustration, the OLT +chooses to send only S sections this time, S ≤ N. + + OLT->>ONU: Download section (instance, section 0, 31 bytes of image data) + Note right of OLT: ... + OLT->>ONU: Download section (instance, section S-1, 31 bytes of image data) [AR] + ONU-->>OLT: Download section response (instance, success, section S-1) + + Note left of OLT: The OLT transmits the final window. +For illustration, F sections (F ≤ N) are assumed +with padding required in section F-1. The OLT chooses +to send only F sections, rather than an additional +(N - F) trailing padding-only section. + + OLT->>ONU: Download section (instance, section 0, 31 bytes of image data) + Note right of OLT: ... + OLT->>ONU: Download section (instance, section F-1, 31 bytes of image data padded with nulls) [AR] + ONU-->>OLT: Download section response (instance, success, section F-1) + + Note left of OLT: The OLT terminates the software download. + + OLT->>ONU: End software download (instance, CRC-32, image size[, parallel download info]) + ONU-->>OLT: End software download response (instance, success[, parallel download status]) + + Note right of ONU: The ONU terminates software download, +marks its image instance(s) valid. + +``` + +G.988(12)\_Fl.3.2.1-2 + +Sequence diagram of the software download process between an OLT and an ONU. The process involves a start message, window size negotiation, section-by-section download with acknowledgments, a retransmission for a failed window, and a final end download message. + +**Figure I.3.2.1-2 – Software download, baseline message set** + +The ONU should positively acknowledge an end download message only after it has performed whatever operations may be necessary – such as storage in non-volatile memory – to accept an immediate activate or commit message from the OLT. As illustrated in Figure I.3.2.1-3, the ONU should respond with a device busy result code until these operations are complete, and the OLT should periodically retry the end download command. The OLT should include a timeout to detect an ONU that never completes the download operation. + +![Sequence diagram illustrating Busy response handling between OLT and ONU. The OLT sends download sections (0 to N-1). The ONU receives them but responds with 'device busy' for the final section. The OLT retries after a delay with an 'End software download' command. The ONU then responds 'ok'.](d360d5aebb0ef00c50f42cd1d74afbeb_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT sends the last window. + OLT->>ONU: Download section (Software image (section 0, image data)) + OLT->>ONU: Download section (section 1, image data) + Note right of ONU: The ONU successfully receives the window. + OLT->>ONU: Download section (section N-1, image data) [AR = ack rqst] + ONU-->>OLT: Download section response + OLT->>ONU: End software download (instance, CRC-32, image size) + Note right of ONU: CRC32 and image size ok, but the ONU is not ready to activate or commit. + ONU-->>OLT: End software download response (result-reason 0110 = device busy) + Note left of OLT: The OLT retries after a delay. + OLT->>ONU: End software download (instance, CRC-32, image size) + Note right of ONU: CRC and image size ok. The ONU is now ready to commit. The ONU sets valid attribute of software image instance and updates MIB data sync. + ONU-->>OLT: End software download response (ok) + +``` + +G.988(12)\_Fl.3.2.1-3 + +Sequence diagram illustrating Busy response handling between OLT and ONU. The OLT sends download sections (0 to N-1). The ONU receives them but responds with 'device busy' for the final section. The OLT retries after a delay with an 'End software download' command. The ONU then responds 'ok'. + +**Figure I.3.2.1-3 – Busy response handling** + +The nested state machines in the OLT and ONU can conceivably get out of step in a number of unspecified ways; nor is it specified how to escape from a loop of transmission failure and retry. As a recovery mechanism from detectable state errors, it is recommended that the ONU reply with command processing error result codes to both the acknowledged download section and end software download commands, and that the OLT send a final end software download command with a known bad CRC and image size (e.g., all 0), whereupon both the OLT and ONU should reset to the state in which no download is in progress, i.e., state S1/S1' of Figure I.3.1-1. Likewise, the OLT should be able to abort the download operation at any time by sending an end software download message with invalid CRC and image size. + +As well as the download of an image to the ONU as a whole, the download messages allow an option to download an image to each of several circuit packs in parallel. The starting assumption is that the OLT knows the set of circuit packs that require the same download file, so that it can specify this set in the download command sequence. + +### I.3.2.2 Extended message set download + +The description of clause I.3.2.1 pertains also to download using the extended OMCI message set, except that the maximum size of the section is limited by the extended message format itself, and is potentially as large as 1965 bytes. The OLT may send smaller sections at will, including the final section of a file transfer. Because the extended message format allows for variable length, software image sections are never padded in this message format. + +The negotiation of the window size is governed by two opposing criteria: 1) maximize throughput and 2) avoid ONU receive buffer overflow. A problem arises if the ONU supports both baseline message set and extended message set. At the time when the ONU negotiates the window size, the ONU does not know whether the OLT will use baseline or extended message set for the download. If + +the ONU assumes the OLT will use extended message set for software download but the OLT actually uses baseline message set, then the ONU will choose a small window size and the throughput could be low. If the ONU assumes the OLT will use baseline message set for software download but the OLT actually uses extended message set, then the ONU will choose a large window size and the ONU receive buffer could overflow. + +Although ITU-T G.989.3 allows the OLT to switch between baseline and extended message set on subsequent messages, the following OLT behaviour is recommended (not mandatory) to prevent the resource constrained ONU from overflowing OR negotiating a low throughput: + +- If the OLT uses baseline "Start Download" message then all subsequent "Download segment" messages should also use baseline message format. Likewise if the OLT uses extended "Start Download" message then all subsequent "Download segment" message should also uses extended message format. The ONU can respond with an appropriate window size based on the knowledge of the message set the OLT intends to use based on the "Download segment" message +- If the OLT supports OLT-G ME, the ONU can derive the OLT use of baseline or extended message set in software download based on a priori knowledge of the vendor/equipment information. + +### **I.3.3 Software image activate and commit** + +Figure I.3.3-1 shows the details of software image activate and commit. When the ONU has downloaded and validated a new image, that image is initially not-committed and not-activated. The OLT may then send the activate image command. After the ONU sends a positive activate image response, the ONU loads and executes the new software image, but without changing the committed state of either image. The OLT may then send the commit image command, causing the ONU to set the commit state true for the new image, and false for the previous image. The time between the download, activate and commit phases is not specified. + +If there is a problem with the newly activated image that causes the ONU to fail (e.g., watchdog timeout), the ONU should do a soft restart on the (other) committed image. Activating prior to committing may thereby allow for automatic failure recovery by the ONU. + +![Sequence diagram showing the software activate and commit process between an OLT and an ONU. The process involves activating a software image instance, restarting the ONU, committing the image, and finalizing the update on both sides.](0eae447995c0dcb49ce6b55795609787_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + OLT->>ONU: Activate image (software image (instance)) + Note right of ONU: The ONU updates its MIB and increments its MIB data sync. + ONU->>OLT: Activate image response + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + Note right of ONU: The ONU restarts with a new image, which is now active but uncommitted. + Note left of OLT: After a successful start-up sequence, the OLT decides to commit the active software image. + OLT->>ONU: Commit image (software image (instance)) + Note right of ONU: The ONU updates its MIB and increments its MIB data sync. + ONU->>OLT: Commit image response + Note left of OLT: The OLT updates its MIB and increments its MIB data sync. + +``` + +G.988(12)\_FI.3.3-1 + +Sequence diagram showing the software activate and commit process between an OLT and an ONU. The process involves activating a software image instance, restarting the ONU, committing the image, and finalizing the update on both sides. + +**Figure I.3.3-1 – Software activate and commit** + +## I.4 Performance monitoring + +The tools used for PM are as follows. + +- The PM history data and extended PM MEs. PM is defined in clause 9 for many ONU functions including GEM adaptation, CES, Ethernet service and voice service. +- The synchronize time action on the ONU-G ME. This action synchronizes all PM MEs to a common 15 min collection interval starting point. +- The threshold data 1 and threshold data 2 ME pair. These MEs provide thresholds for the TCA function. +- The TCA notification, which alerts the OLT to a threshold crossing event. + +PM MEs share a number of characteristics, as described in this clause. Exceptions to the generic behaviour are defined in the specific ME affected. + +Two groups of PM MEs are defined as follows. + +- 1) Classical PM, whose members are identified by names containing the string, "performance monitoring history data". +- 2) Extended PM, whose members are identified by names containing the string, "extended PM". + +All PM MEs are created and deleted by the OLT. + +The remainder of this parent clause describes behaviour common to the two classes of PM MEs. Aspects unique to each PM ME class are discussed in the following subclauses. + +### PM collection intervals + +Classical PM, and optionally extended PM, are based on the assumption of a continuing sequence of 15 min intervals. This sequence of 15 min intervals is coordinated by the synchronize time action, issued by the OLT against the ONU-G ME. The synchronize time action resets all PM attributes, + +establishes a 15 min tick boundary and starts numbering the intervals from 0. The interval number is represented by the interval end time attribute of the PM ME, a single byte counter that rolls over from 255 to 0. + +The synchronize time action is the only mechanism guaranteed to reset either the phase or the interval number. For example, neither ONU re-boot nor MIB reset can be expected to have these effects (the PM consequence of these events is undefined). In the absence of a synchronize time message, an ONU would be expected to maintain 15 min intervals asynchronously with the outside world, and with an incrementing but arbitrary interval identifier. + +No explicit mechanism is provided to synchronize a new PM ME that may be created on a working ONU. Best practice suggests that the ONU run all of its 15 min PM according to a single ONU-wide 15 min timer and interval counter. + +The ONU does not perform any calculations upon the collected data nor does it keep an archive of collected data beyond the previous 15 min interval. Archiving and analysis, if required, are performed by a higher order network element such as the OLT or EMS, along with possible accumulation into 24 h statistics. + +In 15 min accumulation mode, as distinguished from the optional continuous accumulation mode of the extended PM MEs, the ONU conceptually has only two storage bins for each PM ME instance: a current accumulator and a history bin. At 15 min intervals, they switch roles. History is discarded at age 30 min, when the previous history bin is initialized into its role as the new current accumulator. The previous accumulator, now in its role as the history bin, retains its totals for 15 min, so that the OLT can upload them if desired. + +In 15 min accumulation mode, the get action on a PM ME returns the values of attributes in the history bin. An ONU may also support an optional action in 15 min accumulation mode, get current data. The effect of this action is to return the value of attributes in the current accumulator. When a PM attribute is an average or a ratio, it acquires a value only at the end of a 15 min interval. The value returned by a get current data operation is undefined (0xFF in every byte would be reasonable). + +### **Thresholds and alerts** + +The OMCI supports PM thresholds and TCAs. Not all PM attributes can be thresholded; threshold definition and assignment is part of the specification of each PM attribute. + +The PM ME definition includes a pointer to threshold data MEs, a null pointer by default. If the OLT does not require TCAs, it leaves the pointer undefined. To enable thresholds, the OLT creates an instance of the threshold data 1 ME, and if any of the required thresholds is numbered above 7, also an instance of the threshold data 2. The OLT then populates the threshold data attributes with threshold values in accordance with the mapping defined in each type of PM ME. + +Any number of PM ME instances may subscribe to a given set of thresholds. + +Most performance attributes are counters. During the accumulation interval, the PM ME collects counter statistics in accordance with each PM attribute definition, and continuously compares the accumulated values with any thresholds that may exist. When an accumulated value first equals or exceeds the threshold, the ONU originates a TCA. + +If a counter PM attribute should fill up during the interval, it remains at its maximum possible value, rather than rolling over. + +The threshold for a given counter attribute may be disabled by setting it either to 0 or to 0xFFFF. It may also be effectively disabled by setting it to a value greater than the range of the counter, e.g., a value greater than 900 when used for an ES PM attribute. + +The OLT may modify a threshold attribute at any time. If the modification lowers the threshold such that it has already been passed, the TCA is reported when the current value is next compared with the threshold value. This comparison is specific to the ONU's architecture, so that the timing or even the existence of a TCA during the current interval cannot be guaranteed. + +Regardless of the origin of a given TCA, the ONU issues a second TCA at the end of the current 15 min interval, cancelling the first. That is, each 15 min interval begins with all previous TCAs explicitly cleared via notifications to the OLT. + +When a PM attribute is an average or a ratio, its value is computed only at the end of the interval. A TCA on such an attribute can therefore be declared only at the end of the interval. The TCA is then immediately cleared as the accumulator is reset for the next interval. The definition of a given PM attribute may specify different or more detailed behaviour. + +When a PM attribute is a high-water-mark, a TCA is declared when the monitored parameter equals or exceeds the threshold value from below; conversely for a low-water-mark attribute. There is no general definition of the mechanism to clear the TCA, nor specification of delay or hysteresis to avoid TCA storms for a parameter fluctuating near the threshold value. These should be defined in the specification of each PM attribute. + +TCAs are reported in OMCI alarm messages. There is no overlap between TCA code points and alarm code points, because a given ME class declares either alarms or TCAs, but not both. + +### **MIB sync** + +The control block of a PM ME contains persistent data that can be set by the OLT. Setting the value of a control block attribute therefore increments the MIB data sync attribute of the ONU data ME. In addition, the control block attribute of a PM ME is included in an MIB upload. Other PM attributes are transient and are not included in MIB uploads. + +### **Template for the definition of a PM ME** + +Existing PM generally follows the following outline. Significant exceptions are discussed here; an implementation is advised to be aware that the definitions of individual MEs and attributes may contain other exceptions. + + + +*Relationships* + + + +*Attributes* + +**Managed entity ID:** This attribute is discussed further in separate subsequent clauses. + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. (R) (mandatory) (1 byte) + +**Control block:** This attribute is discussed further in separate subsequent clauses. In classical PM, it is just a pointer to threshold data MEs. + +**PM1:** Definition of the first PM accumulation attribute, in most cases a counter, in other cases, an average, a high water-mark or a low water-mark. The recommended size of a PM accumulation attribute is 4 bytes, but definitions vary. (R) (mandatory) (4 bytes) + +**PM2:** + +... Definition of additional PM accumulation attributes, maximum not to exceed 14. There is no particular preference on the order in which parameters are defined. + +### Actions + +Create, delete, get, set + +Get current data (optional) + +### Notifications + +The TCA table lists thresholded attributes in order. It is not required that all attributes be thresholdable. The alarm number column identifies a bit in the alarm bit map field of the OMCI alarm message that is used to report TCAs. Alarm numbering starts at 0. + +The threshold data counter column assigns threshold attributes of the threshold data 1 and if required, the threshold data 2 MEs. In all cases, the assignment is monotonic, but existing PM definitions may or may not skip a threshold attribute for each PM attribute that is to be thresholded. In future PM definitions, it is recommended that threshold attributes be assigned sequentially, without gaps. If, for example, the only thresholded PM attributes were the first, third and sixth in order of PM ME definition, they would still be assigned threshold attributes 1, 2, 3. + +#### Threshold crossing alert + +| Alarm number | Threshold crossing alert | Threshold data counter No. (Note) | +|--------------|--------------------------|-----------------------------------| +| 0 | PM1 | 1 | +| 1 | PM2 | 2 | +| 2 | ... | 3 | +| 3 | | 4 | + +NOTE – This number associates the TCA with the specified threshold value attribute of the threshold data 1 managed entity. + +### I.4.1 Classical PM + +Unneeded PM accumulation may impose an unnecessary load on the ONU host processor and should be avoided. In classical PM, parameter collection can be disabled only by deleting the PM ME. + +In classical PM, the ME ID attribute takes the same value as the parent ME's ID, so that no explicit pointer to the parent ME is required. The ME class of the parent is fixed in the definition of the classical PM ME. + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. Through an identical ID, this ME is implicitly linked to an instance of a . (R, set-by-create) (mandatory) (2 bytes) + +In classical PM, the control block attribute is always a simple pointer to a threshold data ME, and is designated as such. The attribute value may be set to a null pointer if no thresholding is desired. If no assigned threshold number exceeds 7, it is the OLT's option whether to create a threshold data 2 ME or not. The template text reads as follows, depending on the highest threshold attribute assigned: + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 and 2 MEs that contains PM threshold values. (R, W, set-by-create) (mandatory) (2 bytes) + +Or: + +**Threshold data 1/2 ID:** This attribute points to an instance of the threshold data 1 ME that contains PM threshold values. Since no threshold value attribute number exceeds 7, a threshold data 2 ME is optional. (R, W, set-by-create) (mandatory) (2 bytes) + +#### I.4.2 Extended PM + +In extended PM, the control block attribute is defined to be (R, W, set-by-create) (mandatory) (16 bytes). The template for these 16 bytes is as follows: + +**Threshold data 1/2 ID:** (2 bytes). The definition of this field is the same as for that in classical PM. + +NOTE – When PM is collected on a continuously running basis, rather than in 15 min intervals, counter thresholds should not be established. There is no mechanism to clear a TCA, and any counter parameter may eventually be expected to cross any given threshold value. + +**Parent ME class:** (2 bytes). This field contains the enumerated value of the ME class of the PM ME's parent, as defined in Table 11.2.4-1. Together with the parent ME instance field, this permits a given PM ME to be associated with any OMCI ME. The definition of an extended PM ME should list the allowed parent ME classes. + +**Parent ME instance:** (2 bytes). This field identifies the specific parent ME instance to which the PM ME is attached. + +**Accumulation disable:** (2 bytes). This bit field allows PM accumulation to be disabled; refer to Table I.7.2-1. Bit value 0 enables PM collection. If bit 15 is set to 1, no PM is collected by this ME instance. If bit 15 = 0 and any of bits 14..1 are set to 1, PM collection is inhibited for the attributes indicated by the 1 bits. Inhibiting PM collection does not change the value of a PM attribute, but if PM is accumulated in 15 min intervals, the value is lost at the next 15 min interval boundary. + +Bit 16 is an action bit that always reads back as 0. When written to 1, it resets all PM attributes in the ME, and clears any TCAs that may be outstanding. + +**TCA disable:** (2 bytes) Also clarified in Table I.4.2-1, this field permits TCAs to be inhibited, either individually or for the complete ME instance. As with the accumulation disable field, bit value 0 enables TCAs, and setting the global disable bit overrides the settings of the individual thresholds. Unlike the accumulation disable field, the bits are mapped to the thresholds defined in the associated threshold data 1 and 2 ME instances. When the global or attribute-specific value changes from 0 to 1, outstanding TCAs are cleared, either for the ME instance globally or for the individual disabled threshold. These bits affect only notifications, not the underlying parameter accumulation or storage. + +If the threshold data 1/2 ID attribute does not contain a valid pointer, this field is not meaningful, since no TCAs are possible. + +**Table I.4.2-1 – Bit assignments in extended PM control block** + +| Bit | 16 | 15 | 14 | 13 | 3 | 2 | 1
(LSB) | +|-----------------------------|--------------|----------------|------|-----|-----|-----|------------| +| Accumulation disable | Global clear | Global disable | PM14 | ... | ... | PM2 | PM1 | +| TCA disable | | Global disable | Th14 | ... | ... | Th2 | Th1 | + +**Control fields:** (2 bytes). This field is a bit map whose values govern the behaviour of the extended PM ME. Bits are assigned as follows: + +- Bit 1 (LSB) The value 1 specifies continuous accumulation, regardless of 15 min intervals. There is no concept of current and historical accumulators; get and get current data (if supported) both return current values. Accumulated values are only reset by the clear flags, not by any timed or other action. The value 0 specifies 15 min accumulators exactly like those of classical PM. +- Bit 2 The value 0 specifies directionality, for example upstream or downstream, or up/down in an [IEEE 802.1ag] sense with respect to a bridge port. If this bit is meaningful, the details are part of the definition of the extended PM ME. +- Bits 3..16 Reserved. Starting from bit 16, and working downwards, these bits may be used in the definition of individual extended PM MEs. Continuing upwards from bit 3, these bits may be used for additional purposes that pertain to all extended PM MEs. + +For example, in a VLAN extended PM ME, bits 16-15 could be used to match P bits, VID or both. + +**Reserved:** (4 bytes). These bytes are available for customization in the definition of each extended PM ME. + +For example, in a VLAN extended PM ME, two of these bytes could be used to specify TCI. + +The other template boiler plate fields are revised in extended PM to read as follows: + +**Managed entity ID:** This attribute uniquely identifies each instance of this ME. To facilitate discovery, the identification of instances sequentially starting with 1 is encouraged. (R, set-by-create) (mandatory) (2 bytes) + +**Interval end time:** This attribute identifies the most recently finished 15 min interval. If continuous accumulation is enabled in the control block, this attribute is not used and has the fixed value 0. (R) (mandatory) (1 byte) + +**Threshold data 1/2 ID:** . Thresholding is not advised for counter attributes if PM is accumulated continuously. (R, W, set-by-create) (mandatory) (2 bytes) + +It is not expected that the PM accumulation policy will be changed in actual deployment practice, and the behaviour of intervals, TCAs and accumulated history across a transition between continuous and interval accumulation is not specified. It may be desirable to disable and clear PM at such a transition. + +The synchronize time action has no observable effect on PM that is accumulated continuously. + +Counter PM attributes do not roll over in interval PM mode, but do roll over from maximum to zero in continuous accumulation mode. PM attributes that record averages or ratios are undefined in continuous accumulation mode. Both of these behaviours may be overridden by explicit specification in the definition of a given extended PM ME. + +## Appendix II + +### G-PON mechanisms and services + +(This appendix does not form an integral part of this Recommendation.) + +NOTE – When text in this clause refers to the IP host config data ME, or to an IP stack, it is understood to include the IPv6 host config data ME, or an IPv6 stack, as modified suitably by the differences between IPv4 and IPv6. + +This appendix describes mechanisms and services that are common to G-PON systems, as described in the relevant TC layer specification. + +#### II.1 Layer 2 data service according to [b-BBF TR-156] + +##### II.1.1 Requirements base + +[b-BBF TR-156] provides Broadband Forum's core set of requirements for layer 2 data service functionality within a G-PON access node. [b-BBF TR-156] addresses three network service architectures as follows. + +- 1) 1:1 VLANs – Indicates a one-to-one mapping between user port and VLAN. The uniqueness of the mapping is maintained in the G-PON access node and across the aggregation network. +- 2) *N*:1 VLANs – Many-to-one mapping between user ports and VLAN. The user ports may be located in the same or different G-PON access nodes. +- 3) VLANs for business Ethernet services (VBES, also known as TLS) – Transparent transport of incoming frames as they arrive at the UNIs regardless of whether they are VLAN tagged, priority tagged or untagged. + +It is desirable to implement G-PON systems with at least the layer 2 OMCI common model (L2-OCM) defined in this appendix, which supports the requirements of [b-BBF TR-156]. A system may also support additional OMCI layer 2 models or extend the common model. + +This appendix describes recommended provisioning models and message sequences to support [b-BBF TR-156]. However, it is important to recognize that the OLT and ONU have a master-slave relationship, with the OLT as master. Therefore, the OLT may choose to provision the ONU with only a subset of the models described in this appendix or a subset of the functionality defined in [b-BBF TR-156], and the ONU should act as commanded by the OLT. Only if the OLT requests ONU actions that are beyond the capabilities represented here, is the OLT considered to be performing outside of the scope of this appendix. + +#### II.1.2 Layer 2 unicast data services + +##### II.1.2.1 Single UNI OMCI provisioning model + +The L2-OCM is the minimum that should be supported by all G-PON systems. It is based on the 1:MP model of Figure 8.2.2-7. This model combines MAC bridging and IEEE 802.1p mapping functionality for a single UNI. Figure II.1.2.1-1 illustrates L2-OCM applied to a single UNI ONU. Figure II.1.2.1-1 assumes an Ethernet UNI, but the same provisioning model can be used for other UNI types. + +![Figure II.1.2.1-1: Single UNI, two VLANs with common priorities. This block diagram illustrates the provisioning for two VLANs sharing common priorities. On the left, a UNI (consisting of PPTP Ethernet UNI and UNI-G) is connected to a MAC bridge service profile. The PPTP Ethernet UNI receives 'Ext VLAN tag operation config data' and is associated with four downstream priority queues (A1, A2, A3, A4). The MAC bridge service profile is linked to a 'MAC bridge port config data' block, which in turn connects to a 'MAC bridge port filter table data' block and a 'VLAN tagging filter' block. The 'VLAN tagging filter' feeds into an '802.1p mapper service profile'. This profile is connected to two 'GEM interworking TP' blocks. The top 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 1', which is associated with 'Traffic descriptor (downstream)', 'PQ A1', 'Traffic descriptor (upstream)', and a 'T-CONT'. The bottom 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 2', which is associated with 'Traffic descriptor (downstream)', 'PQ A2', 'Traffic descriptor (upstream)', and a 'T-CONT'. The '802.1p mapper service profile' also connects to a 'MAC bridge port config data' block, which is linked to a 'MAC bridge port filter pre-assign table' block and a 'VLAN tagging filter' block. The 'VLAN tagging filter' feeds into another '802.1p mapper service profile'. This profile is connected to three 'GEM interworking TP' blocks. The top 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 1', which is associated with 'Traffic descriptor (downstream)', 'PQ A1', 'Traffic descriptor (upstream)', and a 'T-CONT'. The middle 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 2', which is associated with 'Traffic descriptor (downstream)', 'PQ A2', 'Traffic descriptor (upstream)', and a 'T-CONT'. The bottom 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 3', which is associated with 'Traffic descriptor (downstream)', 'PQ A3', 'Traffic descriptor (upstream)', and a 'T-CONT'. The '802.1p mapper service profile' also connects to a 'MAC bridge port config data' block, which is linked to a 'MAC bridge port filter pre-assign table' block and a 'VLAN tagging filter' block. The 'VLAN tagging filter' feeds into a third '802.1p mapper service profile'. This profile is connected to a 'GEM interworking TP' block, which connects to a 'GEM port network CTP' labeled 'PQ 4', which is associated with 'Traffic descriptor (downstream)', 'PQ A4', 'Traffic descriptor (upstream)', and a 'T-CONT'. The 'GEM port network CTP' for 'PQ 4' is also associated with 'Priority queue 4 (upstream)'. The 'GEM port network CTP' for 'PQ 3' is also associated with 'Priority queue 3 (upstream)'. The 'GEM port network CTP' for 'PQ 2' is also associated with 'Priority queue 2 (upstream)'. The 'GEM port network CTP' for 'PQ 1' is also associated with 'Priority queue 1 (upstream)'. The diagram is labeled 'G.988(12)_FII.1.2.1-1' in the bottom right corner.](eb8b7df8a0c294b217f369f3ab60d0b5_img.jpg) + +Figure II.1.2.1-1: Single UNI, two VLANs with common priorities. This block diagram illustrates the provisioning for two VLANs sharing common priorities. On the left, a UNI (consisting of PPTP Ethernet UNI and UNI-G) is connected to a MAC bridge service profile. The PPTP Ethernet UNI receives 'Ext VLAN tag operation config data' and is associated with four downstream priority queues (A1, A2, A3, A4). The MAC bridge service profile is linked to a 'MAC bridge port config data' block, which in turn connects to a 'MAC bridge port filter table data' block and a 'VLAN tagging filter' block. The 'VLAN tagging filter' feeds into an '802.1p mapper service profile'. This profile is connected to two 'GEM interworking TP' blocks. The top 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 1', which is associated with 'Traffic descriptor (downstream)', 'PQ A1', 'Traffic descriptor (upstream)', and a 'T-CONT'. The bottom 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 2', which is associated with 'Traffic descriptor (downstream)', 'PQ A2', 'Traffic descriptor (upstream)', and a 'T-CONT'. The '802.1p mapper service profile' also connects to a 'MAC bridge port config data' block, which is linked to a 'MAC bridge port filter pre-assign table' block and a 'VLAN tagging filter' block. The 'VLAN tagging filter' feeds into another '802.1p mapper service profile'. This profile is connected to three 'GEM interworking TP' blocks. The top 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 1', which is associated with 'Traffic descriptor (downstream)', 'PQ A1', 'Traffic descriptor (upstream)', and a 'T-CONT'. The middle 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 2', which is associated with 'Traffic descriptor (downstream)', 'PQ A2', 'Traffic descriptor (upstream)', and a 'T-CONT'. The bottom 'GEM interworking TP' connects to a 'GEM port network CTP' labeled 'PQ 3', which is associated with 'Traffic descriptor (downstream)', 'PQ A3', 'Traffic descriptor (upstream)', and a 'T-CONT'. The '802.1p mapper service profile' also connects to a 'MAC bridge port config data' block, which is linked to a 'MAC bridge port filter pre-assign table' block and a 'VLAN tagging filter' block. The 'VLAN tagging filter' feeds into a third '802.1p mapper service profile'. This profile is connected to a 'GEM interworking TP' block, which connects to a 'GEM port network CTP' labeled 'PQ 4', which is associated with 'Traffic descriptor (downstream)', 'PQ A4', 'Traffic descriptor (upstream)', and a 'T-CONT'. The 'GEM port network CTP' for 'PQ 4' is also associated with 'Priority queue 4 (upstream)'. The 'GEM port network CTP' for 'PQ 3' is also associated with 'Priority queue 3 (upstream)'. The 'GEM port network CTP' for 'PQ 2' is also associated with 'Priority queue 2 (upstream)'. The 'GEM port network CTP' for 'PQ 1' is also associated with 'Priority queue 1 (upstream)'. The diagram is labeled 'G.988(12)\_FII.1.2.1-1' in the bottom right corner. + +**Figure II.1.2.1-1 – Single UNI, two VLANs with common priorities** + +Figure II.1.2.1-1 shows provisioning to provide upstream mapping of two VIDs and the IEEE 802.1p priorities within those VIDs. With the VID selected by a VLAN tagging filter, the upper part of Figure II.1.2.1-1 provisions IEEE 802.1p priorities to two GEM ports, each going to a single priority queue. In the lower part of Figure II.1.2.1-1, the other VID is provisioned to map IEEE 802.1p priorities to four GEM ports, each going to a single priority queue. + +Figure II.1.2.1-1 shows only four priority queues because this is the minimum requirement of [b-BBF TR-156]. Figure II.1.2.1-1 can easily be extended to six classes of traffic, the objective of [b-BBF TR-156], by adding GEM port network CTPs, GEM IW TPs, priority queues and T-CONTs. + +NOTE – This clause is specific to [b-BBF TR-156], which contemplates only a single queue per T-CONT. Multiple queues per T-CONT are discussed further in clause II.3. + +Figure II.1.2.1-2 depicts another provisioning option using the L2-OCM. This provisioning treats each of the two VLANs as having an implied priority that is beyond the scope of the IEEE 802.1p priority bits; i.e., the P-bit space of one VLAN does not correspond to the same P-bit priorities of the other. The P bits of each VLAN are mapped separately to different queues, thence to different T-CONTs. VID1 is mapped to one bridge port and IEEE 802.1p mapper, while VID2 is mapped to another bridge port and mapper. Each IEEE 802.1p mapper maps P-bit values 2 and 3 (for example) to separate priority queues, resulting in four distinct priority flows, both upstream and down. By grooming traffic into separate T-CONTs, the option is available for the OLT to provide different service levels, even for traffic with the same P-bit values. + +![Diagram of Single UNI, two VLANs, VID-based priorities showing traffic flows for VID 1 and VID 2 through various network components like VLAN tagging filters, MAC bridge port config data, 802.1p mapper service profiles, GEM interworking TP, GEM port network CTP, and T-CONTs.](26e9d4e456053012de64ca9c92134409_img.jpg) + +The diagram illustrates the provisioning option for two VLANs (VID 1 and VID 2) using the L2-OCM. It shows the flow of traffic from the UNI (PPTP Ethernet UNI and UNI-G) through various network components to the T-CONTs. + +- VID 1 Path:** + - Ext VLAN tag operation config data feeds into the PPTP Ethernet UNI. + - The PPTP Ethernet UNI connects to the MAC bridge port config data. + - The MAC bridge port config data feeds into the MAC bridge service profile. + - The MAC bridge service profile feeds into the VLAN tagging filter for VID 1. + - The VLAN tagging filter for VID 1 feeds into the 802.1p mapper service profile (P bits = 2). + - The 802.1p mapper service profile (P bits = 2) feeds into the GEM interworking TP. + - The GEM interworking TP feeds into the GEM port network CTP. + - The GEM port network CTP feeds into the PQ 1 (Priority queue 1 (upstream)). + - The PQ 1 feeds into the T-CONT. + - Downstream traffic flows from the T-CONT through the Traffic descriptor (upstream), PQ A1, Traffic descriptor (downstream), and back to the GEM port network CTP. +- VID 2 Path:** + - The MAC bridge service profile also feeds into the MAC bridge port config data for VID 2. + - The MAC bridge port config data for VID 2 feeds into the VLAN tagging filter for VID 2. + - The VLAN tagging filter for VID 2 feeds into the 802.1p mapper service profile (P bits = 3). + - The 802.1p mapper service profile (P bits = 3) feeds into the GEM interworking TP. + - The GEM interworking TP feeds into the GEM port network CTP. + - The GEM port network CTP feeds into the PQ 2 (Priority queue 2 (upstream)). + - The PQ 2 feeds into the T-CONT. + - Downstream traffic flows from the T-CONT through the Traffic descriptor (upstream), PQ A2, Traffic descriptor (downstream), and back to the GEM port network CTP. +- Additional Paths:** + - The MAC bridge service profile also feeds into the MAC bridge port config data for VID 1 (P bits = 2). + - This config data feeds into the 802.1p mapper service profile (P bits = 2). + - This profile feeds into the GEM interworking TP. + - The TP feeds into the GEM port network CTP. + - The CTP feeds into the PQ 3 (Priority queue 3 (upstream)). + - The PQ 3 feeds into the T-CONT. + - Downstream traffic flows from the T-CONT through the Traffic descriptor (upstream), PQ A3, Traffic descriptor (downstream), and back to the GEM port network CTP. +- Similarly, the MAC bridge service profile feeds into the MAC bridge port config data for VID 2 (P bits = 3). +- This config data feeds into the 802.1p mapper service profile (P bits = 3). +- This profile feeds into the GEM interworking TP. +- The TP feeds into the GEM port network CTP. +- The CTP feeds into the PQ 4 (Priority queue 4 (upstream)). +- The PQ 4 feeds into the T-CONT. +- Downstream traffic flows from the T-CONT through the Traffic descriptor (upstream), PQ A4, Traffic descriptor (downstream), and back to the GEM port network CTP. + +Diagram of Single UNI, two VLANs, VID-based priorities showing traffic flows for VID 1 and VID 2 through various network components like VLAN tagging filters, MAC bridge port config data, 802.1p mapper service profiles, GEM interworking TP, GEM port network CTP, and T-CONTs. + +Figure II.1.2.1-2 – Single UNI, two VLANs, VID-based priorities + +### II.1.2.1.1 T-CONT and GEM port usage + +The common OMCI model uses four T-CONTs, each representing a single logical connection group associated with an alloc-ID. To meet [b-BBF TR-156] requirements, each T-CONT transports a single traffic class, and with only one priority queue. One queue per T-CONT relieves the ONU of most of its upstream QoS responsibilities; the bandwidth allocation algorithm in the OLT governs QoS in fine detail. + +Each T-CONT ME is instantiated with its policy attribute set to the ONU's default; since only one priority queue is associated with the T-CONT, the policy attribute should be treated as a "don't care" by the OLT. Clause II.3 discusses QoS management when a T-CONT is served by more than one queue. + +Each T-CONT is associated with 1 to $N$ GEM ports by way of its upstream priority queue. Each GEM port is represented in the model by a GEM IW TP and a GEM port network CTP. The following provisioning considerations pertain to these MEs: + +#### **GEM interworking TP** + +- The GEM port network CTP connectivity pointer attribute is set to point to the partner GEM port network CTP ME. +- The IW option, service profile pointer, and GAL profile pointer attributes should all be set according to the IEEE 802.1p mapper service option. +- The IW TP pointer attribute is set to 0 and not used. + +#### **GEM port network CTP** + +- The direction attribute is set to 3 to indicate a bidirectional GEM port. +- The priority queue pointer for the downstream attribute should point to the desired downstream priority queue. However, downstream frames arriving at the GEM port are conceptually routed through the IEEE 802.1p mapper and MAC bridge, where tagging and filtering operations may be performed, rather than directly transferred to the downstream priority queue. Therefore, it is important that the provisioning of the MAC bridge and the priority queue pointer attribute agree on the destination UNI for downstream frames. The consequences of inconsistent provisioning are not defined. +- The traffic management pointer for upstream, traffic descriptor profile pointer for upstream, and traffic descriptor profile pointer for downstream attributes should be supported. For detailed information on the use of the traffic attributes, refer to clause II.3. + +##### **II.1.2.1.2 Classification and marking** + +The extended VLAN tagging operation data ME provides classification and marking of ingress frames at the UNI. This includes the ability to add tags based on Ethertype and to set IEEE 802.1p P-bit values based on DSCP. + +##### **II.1.2.1.3 MAC address filtering** + +Figure II.1.2.1-1 depicts a MAC bridge port filter pre-assign table ME and a MAC bridge port filter table data ME associated with the ANI side MAC bridge port configuration data MEs. While these MEs are automatically created by the ONU upon creation of all MAC bridge port configuration data MEs, the diagram is simplified by showing only the ANI side MEs. These MEs are used in the following manner (filtering applies to frames exiting the MAC bridge port): + +- The MAC bridge port filter pre-assign table ME filters frames based on predefined addresses or Ethertype. The list of filter options is defined in clause 9.3.7. +- The MAC bridge port filter table data ME filters frames based on specific MAC addresses. MAC address learning should be disabled prior to the setting of table entries. [b-BBF TR-156] requires support only for upstream MAC address filtering. + +NOTE – MAC address filtering is supported in all models (single UNI, multiple UNI, single and multiple UNI with multicast) but is only shown in Figure II.1.2.1-1 to minimize the complexity of figures depicting the more complex models. + +#### II.1.2.1.4 Flow routing + +Flow routing within the ONU is provisioned using a combination of the MAC bridge ME group and the IEEE 802.1p mapper service profile. + +The MAC bridge ME group supports flow routing based on VID, with the following provisioning considerations. + +- With the exception of the MAC bridge port filter MEs, the L2-OCM diagram in Figure II.1.2.1-1 is simplified to show only MAC bridge MEs that are created by the OLT. The ONU automatically instantiates several additional MEs when a MAC bridge service profile or MAC bridge port config data ME is created by the OLT. The ONU should support these MEs for completeness of overall MAC bridge functionality. +- The VLAN tagging filter data ME implements VID-based flow mapping. In cases where VID flow mapping is not required, this ME need not be created, and only a single ANI side MAC bridge port config datum and a single IEEE 802.1p mapper are needed. +- The MAC bridge model does not map subscriber data flows based on P-bits. This functionality resides in the IEEE 802.1p mapper. + +The IEEE 802.1p mapper service profile supports upstream flow routing based on IEEE 802.1p priority bits, with the following provisioning considerations. + +- The TP pointer attribute should be set to null, as required for a bridging-mapping model. +- The TP type attribute should be set to 0, to indicate that a bridging-mapping model is being used. + +#### II.1.2.1.5 Message flows + +Figures II.1.2.1.5-1 to II.1.2.1.5-6 depict the core message flow used to create the L2-OCM. Each figure represents a step within the flow. Each step may be performed multiple times to produce multiple ME instances. It is recommended that the depicted ordering of steps and the ordering of messages within those steps be followed to ensure that no ME pointer attribute is populated prior to the creation of its target ME. Since the GEM IW TP ME and the IEEE 802.1p mapper service profile ME point to each other, it is particularly important to create the IEEE 802.1p mapper service profile ME with null interwork TP pointers for P-bit priority attributes. Only in step 5, after the GEM IW TP MEs have been created, are the mapper's attributes populated with pointers to the MEs. + +![Sequence diagram for Step 1 of L2-OCM message flow between OLT and ONU.](96e3a8ea926d522da70a0d63e7f5089f_img.jpg) + +This sequence diagram illustrates Step 1 of the L2-OCM message flow. It shows the OLT sending a 'Create (GEM port network CTP)' message to the ONU, and the ONU responding with a 'Create response'. A bracket on the right side indicates this exchange occurs 'Once per T-CONT'. The diagram is labeled 'G.988(12)\_FII.1.2.1.5-1'. + +Sequence diagram for Step 1 of L2-OCM message flow between OLT and ONU. + +Figure II.1.2.1.5-1 – L2-OCM message flow – Step 1 + +![Sequence diagram for Step 2 of L2-OCM message flow between OLT and ONU.](6bd47b1a306f0e35864cdca552353223_img.jpg) + +This sequence diagram illustrates Step 2 of the L2-OCM message flow. It shows two sets of messages between the OLT and the ONU. The first set consists of 'Create (GAL Ethernet profile)' and 'Create response', with a bracket indicating this occurs 'At least once per ONU'. The second set consists of 'Create (MAC bridge service profile)' and 'Create response', with a bracket indicating this occurs 'Once per UNI'. The diagram is labeled 'G.988(12)\_FII.1.2.1.5-2'. + +Sequence diagram for Step 2 of L2-OCM message flow between OLT and ONU. + +Figure II.1.2.1.5-2 – L2-OCM message flow – Step 2 + +![Sequence diagram showing L2-OCM message flow for Step 3 between OLT and ONU. The OLT sends a 'Create (802.1p mapper service profile)' message to the ONU, which responds with 'Create response'. Next, the OLT sends 'Create (MAC bridge port config data)'. The ONU automatically creates instances of MAC bridge port designation data, MAC bridge port filter table data, and MAC bridge port bridge table data, responding with 'Create response'. Then, the OLT sends 'Create (VLAN tagging filter data)' and the ONU responds with 'Create response'. A bracket on the right side groups the last three messages as 'Once per ANI-side MAC bridge port'. The diagram is labeled G.988(12)_FII.1.2.1.5-3.](d0b7cc026701eaf4a8334cdaebd0bd6f_img.jpg) + +Sequence diagram showing L2-OCM message flow for Step 3 between OLT and ONU. The OLT sends a 'Create (802.1p mapper service profile)' message to the ONU, which responds with 'Create response'. Next, the OLT sends 'Create (MAC bridge port config data)'. The ONU automatically creates instances of MAC bridge port designation data, MAC bridge port filter table data, and MAC bridge port bridge table data, responding with 'Create response'. Then, the OLT sends 'Create (VLAN tagging filter data)' and the ONU responds with 'Create response'. A bracket on the right side groups the last three messages as 'Once per ANI-side MAC bridge port'. The diagram is labeled G.988(12)\_FII.1.2.1.5-3. + +**Figure II.1.2.1.5-3 – L2-OCM message flow – Step 3** + +![Sequence diagram showing L2-OCM message flow for Step 4 between OLT and ONU. The OLT sends a 'Create (GEM interworking TP)' message to the ONU, which responds with 'Create response'. A bracket on the right side groups these two messages as 'Once per GEM port'. The diagram is labeled G.988(12)_FII.1.2.1.5-4.](0ffe86fbf2e7bd0c67db6f42c12df734_img.jpg) + +Sequence diagram showing L2-OCM message flow for Step 4 between OLT and ONU. The OLT sends a 'Create (GEM interworking TP)' message to the ONU, which responds with 'Create response'. A bracket on the right side groups these two messages as 'Once per GEM port'. The diagram is labeled G.988(12)\_FII.1.2.1.5-4. + +**Figure II.1.2.1.5-4 – L2-OCM message flow – Step 4** + +![Sequence diagram showing L2-OCM message flow for Step 5 between OLT and ONU. The OLT sends a 'Set (802.1p mapper service profile (interwork pointer -> GEM IW TP))' message to the ONU, which responds with 'Set response'. A bracket on the right side groups these two messages as 'Once per mapped priority per 802.1p mapper'. The diagram is labeled G.988(17)_FII.1.2.1.5-5.](c5fa016850a6c800ca28678984d2d7f4_img.jpg) + +Sequence diagram showing L2-OCM message flow for Step 5 between OLT and ONU. The OLT sends a 'Set (802.1p mapper service profile (interwork pointer -> GEM IW TP))' message to the ONU, which responds with 'Set response'. A bracket on the right side groups these two messages as 'Once per mapped priority per 802.1p mapper'. The diagram is labeled G.988(17)\_FII.1.2.1.5-5. + +**Figure II.1.2.1.5-5 – L2-OCM message flow – Step 5** + +![Sequence diagram showing L2-OCM message flow for Step 6 between OLT and ONU. The OLT sends a 'Create (MAC bridge port config data)' message to the ONU. The ONU automatically creates instances of MAC bridge port designation data, MAC bridge port filter table data, and MAC bridge port bridge table data, responding with 'Create response'. Then, the OLT sends 'Create (extended VLAN tagging operation config data)' and the ONU responds with 'Create response'. Next, the OLT sends 'Set (extended VLAN tagging operation config data, tagging rules)' and the ONU responds with 'Set response'. A bracket on the right side groups all these messages as 'Once per UNI'. The diagram is labeled G.988(12)_FII.1.2.1.5-6.](632aadfb9a6ece4d43d15b4bd72efd73_img.jpg) + +Sequence diagram showing L2-OCM message flow for Step 6 between OLT and ONU. The OLT sends a 'Create (MAC bridge port config data)' message to the ONU. The ONU automatically creates instances of MAC bridge port designation data, MAC bridge port filter table data, and MAC bridge port bridge table data, responding with 'Create response'. Then, the OLT sends 'Create (extended VLAN tagging operation config data)' and the ONU responds with 'Create response'. Next, the OLT sends 'Set (extended VLAN tagging operation config data, tagging rules)' and the ONU responds with 'Set response'. A bracket on the right side groups all these messages as 'Once per UNI'. The diagram is labeled G.988(12)\_FII.1.2.1.5-6. + +**Figure II.1.2.1.5-6 – L2-OCM message flow – Step 6** + +### II.1.2.2 Multiple UNI OMCI provisioning model + +The multiple UNI L2-OCM is an extension to the single UNI model shown in Figure II.1.2.1-1. As illustrated in Figure II.1.2.2-1, the extension is accomplished by adding another instance of the single UNI L2-OCM for each UNI. It is important to note that there are still the same number of upstream queues and T-CONTs as in the single-UNI diagram. + +For clarity of presentation, Figure II.1.2.2-1 does not include as many GEM ports per UNI as does Figure II.1.2.1-1. However, the underlying functionality associated with each UNI is the same. + +![Figure II.1.2.2-1 – Multi-UNI L2-OCM. A complex block diagram showing two parallel processing paths for network traffic from UNI-G and PTP Ethernet UNI interfaces. Each path includes priority queue management, MAC bridge configuration, VLAN tagging, 802.1p mapping, GEM interworking, and GEM port network CTPs leading to traffic descriptors and T-CONTs.](4fa324c90f3ce15bfe924080ae24eedb_img.jpg) + +The diagram illustrates the Multi-UNI L2-OCM architecture, showing two parallel processing paths for network traffic. + +**Top Path (UNI-G and PTP Ethernet UNI):** + +- UNI-G** and **PTP Ethernet UNI** are connected to a central **MAC bridge port config data** block. +- PTP Ethernet UNI** also receives **Ext VLAN tag operation config data** and is associated with four downstream priority queues: **Priority queue A1 (downstream)**, **Priority queue A2 (downstream)**, **Priority queue A3 (downstream)**, and **Priority queue A4 (downstream)**. +- The **MAC bridge port config data** block connects to a **MAC bridge service profile** block. +- The **MAC bridge service profile** block connects to a **MAC bridge port config data** block, which in turn connects to a **VLAN tagging filter** block. +- The **VLAN tagging filter** block connects to an **802.1p mapper service profile** block. +- The **802.1p mapper service profile** block connects to two **GEM interworking TP** blocks. +- Each **GEM interworking TP** block connects to a **GEM port network CTP** block. +- Each **GEM port network CTP** block is associated with a **Traffic descriptor (downstream)**, a **Traffic descriptor (upstream)**, and a **Priority queue (upstream)** (labeled PQ 1, PQ 2, PQ 3, and PQ 4). +- Each **Priority queue (upstream)** block connects to a **T-CONT** block. + +**Bottom Path (UNI-G and PTP Ethernet UNI):** + +- UNI-G** and **PTP Ethernet UNI** are connected to a central **MAC bridge port config data** block. +- PTP Ethernet UNI** also receives **Ext VLAN tag operation config data** and is associated with four downstream priority queues: **Priority queue B1 (downstream)**, **Priority queue B2 (downstream)**, **Priority queue B3 (downstream)**, and **Priority queue B4 (downstream)**. +- The **MAC bridge port config data** block connects to a **MAC bridge service profile** block. +- The **MAC bridge service profile** block connects to a **MAC bridge port config data** block, which in turn connects to a **VLAN tagging filter** block. +- The **VLAN tagging filter** block connects to an **802.1p mapper service profile** block. +- The **802.1p mapper service profile** block connects to two **GEM interworking TP** blocks. +- Each **GEM interworking TP** block connects to a **GEM port network CTP** block. +- Each **GEM port network CTP** block is associated with a **Traffic descriptor (downstream)**, a **Traffic descriptor (upstream)**, and a **Priority queue (upstream)** (labeled PQ 1, PQ 2, PQ 3, and PQ 4). +- Each **Priority queue (upstream)** block connects to a **T-CONT** block. + +**Additional Connections:** + +- The **MAC bridge port config data** block for the bottom path also connects to a **Multicast subscriber config info** block, which in turn connects to a **Multicast operations profile** block. + +Figure II.1.2.2-1 – Multi-UNI L2-OCM. A complex block diagram showing two parallel processing paths for network traffic from UNI-G and PTP Ethernet UNI interfaces. Each path includes priority queue management, MAC bridge configuration, VLAN tagging, 802.1p mapping, GEM interworking, and GEM port network CTPs leading to traffic descriptors and T-CONTs. + +G.988(12)\_FII.1.2.2-1 + +Figure II.1.2.2-1 – Multi-UNI L2-OCM + +#### **II.1.2.2.1 T-CONT and GEM port usage** + +Multiple UNI L2-OCM adds support for additional UNIs without increasing the number of T-CONTs used by a single UNI L2-OCM. However, an additional set of GEM ports distinguishes the separate flows and allows per-UNI service level agreement (SLA) capability in the ONU. GEM ports are provisioned in the same manner as described in clause II.1.2.1.1. + +#### **II.1.2.2.2 Classification and marking** + +Classification and marking are provisioned on a per-UNI basis in the same manner as described in clause II.1.2.1.2. + +#### **II.1.2.2.3 Flow routing** + +Flow routing is provisioned for each UNI through the use of a distinct MAC bridge ME group and set of IEEE 802.1p mappers, as described in clause II.1.2.1.4. + +#### **II.1.2.2.4 Message flows** + +Provisioning of multiple UNI ONUs is accomplished through additional iterations of the message flow described in clause II.1.2.1.5. + +### **II.1.3 Layer 2 multicast data services** + +Within a G-PON ONU, multicast and broadcast capabilities have two applications. The first application is traditional IGMP-controlled (or unconditional) downstream multicast traffic. The second is the transport of infrequent downstream broadcast frames arriving at the network-facing interface of the OLT. This is sometimes referred to as incidental broadcast. + +Both applications require provisioning of data plane functionality. In addition, traditional multicast requires provisioning of control plane functionality. This clause describes provisioning of both data and control planes. + +#### **II.1.3.1 Data plane** + +A G-PON ONU can support both upstream and downstream broadcast or multicast frames. However, the OMCI has no special provision to support upstream broadcast or multicast. + +In contrast, the OMCI accommodates downstream multicast and broadcast provisioning. This accommodation takes into account the point-to-multipoint nature of G-PON, which shares a GEM port across all ONUs on the PON for multicast, and another GEM port for broadcast. The sharing of GEM ports increases the downstream efficiency of the PON by avoiding the need to replicate frames destined for different ONUs. Likewise, multicast and broadcast GEM ports are common to the UNIs of a given ONU. + +Traffic sent over either of these GEM ports may be contained in a VLAN, and more than one VLAN may be present. Multicast or broadcast VLANs may be segregated to different UNIs by filtering at the ANI side MAC bridge port. + +NOTE – The MC operations profile includes the specification of VLANs, which may, in some cases, make ANI-side filtering unnecessary. + +##### **II.1.3.1.1 Single UNI OMCI provisioning model** + +Figure II.1.3.1.1-1 is the relationship diagram for L2-OCM with the addition of the MEs required for multicast/broadcast provisioning. As indicated by the dotted box in this diagram, multicast/broadcast support is built upon the model for unicast provisioning through the addition of two specialized GEM ports. One GEM port is used for multicast traffic and the other is used for incidental broadcast traffic. These are both unidirectional downstream GEM ports. + +In the OMCI provisioning model, the multicast GEM port is represented by a GEM port network CTP ME connected to a multicast GEM IW TP. The multicast GEM IW TP is then connected into the unicast model through a MAC bridge config data ME. Since no upstream traffic flows through this GEM port, there is no need for an IEEE 802.1p mapper between the MAC bridge port config data ME and the multicast GEM IW TP. + +In the OMCI model, the incidental broadcast GEM port is represented by a GEM network CTP ME connected to a GEM IW TP. The GEM IW TP is then connected into the unicast model through a MAC bridge port config data ME. Since no upstream traffic flows through this GEM port, there is no need for an IEEE 802.1p mapper between the MAC bridge port and the GEM IW TP. + +Associated with the MAC bridge port config data MEs connected to each GEM port are VLAN tagging filters. These MEs filter downstream broadcast frames so that only frames destined for the affected UNIs are allowed into the bridge. Since no upstream frames are delivered over the multicast GEM port, MAC address filtering is not needed on the MAC bridge port associated with the multicast GEM IW TP. + +Because the multicast operations profile lists the VLANs accepted by the UNI, best practice in a [b-BBF TR-156] environment is to omit the possible VLAN tagging filter on the multicast GEM IW TP. + +![Figure II.1.3.1.1-1 – L2-OCM with multicast. This block diagram illustrates the architecture of L2-OCM with multicast. On the left, external interfaces include PPTP Ethernet UNI and UNI-G. PPTP Ethernet UNI is connected to Ext VLAN tag operation config data, Priority queue A1 (downstream), Priority queue A2 (downstream), and MAC bridge port config data. UNI-G is connected to Priority queue A3 (downstream) and Priority queue A4 (downstream). MAC bridge port config data feeds into MAC bridge service profile and MAC bridge port config data. MAC bridge service profile feeds into MAC bridge port config data and 802.1p mapper service profile. 802.1p mapper service profile feeds into GEM interworking TP. GEM interworking TP feeds into GEM port network CTP. GEM port network CTP feeds into Traffic descriptor (downstream), PQ A1, Traffic descriptor (upstream), and T-CONT. T-CONT feeds into Priority queue 1 (upstream). This structure is repeated for Priority queues A2, A3, and A4. A dashed box at the bottom contains multicast-specific components: VLAN tagging filter, MAC bridge port config data, GEM IW TP (downstream broadcast), GEM port network CTP, null, Traffic descriptor (downstream), PQ Ay, MAC bridge port config data, Multicast GEM IW TP, GEM port network CTP, null, and Traffic descriptor (downstream). PQ Ax is also shown. The diagram is labeled G.988(12)_FII.1.3.1.1-1.](5a43b8ef2db63ac99a6fb75aa61ebeab_img.jpg) + +Figure II.1.3.1.1-1 – L2-OCM with multicast. This block diagram illustrates the architecture of L2-OCM with multicast. On the left, external interfaces include PPTP Ethernet UNI and UNI-G. PPTP Ethernet UNI is connected to Ext VLAN tag operation config data, Priority queue A1 (downstream), Priority queue A2 (downstream), and MAC bridge port config data. UNI-G is connected to Priority queue A3 (downstream) and Priority queue A4 (downstream). MAC bridge port config data feeds into MAC bridge service profile and MAC bridge port config data. MAC bridge service profile feeds into MAC bridge port config data and 802.1p mapper service profile. 802.1p mapper service profile feeds into GEM interworking TP. GEM interworking TP feeds into GEM port network CTP. GEM port network CTP feeds into Traffic descriptor (downstream), PQ A1, Traffic descriptor (upstream), and T-CONT. T-CONT feeds into Priority queue 1 (upstream). This structure is repeated for Priority queues A2, A3, and A4. A dashed box at the bottom contains multicast-specific components: VLAN tagging filter, MAC bridge port config data, GEM IW TP (downstream broadcast), GEM port network CTP, null, Traffic descriptor (downstream), PQ Ay, MAC bridge port config data, Multicast GEM IW TP, GEM port network CTP, null, and Traffic descriptor (downstream). PQ Ax is also shown. The diagram is labeled G.988(12)\_FII.1.3.1.1-1. + +**Figure II.1.3.1.1-1 – L2-OCM with multicast** + +#### II.1.3.1.1.1 Provisioning considerations + +Both GEM port network CTP MEs are provisioned with the following considerations. + +- The direction attribute should be set to 2, indicating that the associated GEM port is unidirectional downstream. +- The T-CONT pointer attribute is not meaningful. +- The traffic management pointer for the upstream attribute is not meaningful. +- The traffic descriptor profile pointer for the upstream attribute is not meaningful. +- The priority queue pointer for the downstream attribute is used as a template for all UNIs that subscribe to this GEM port. Specifically, if this attribute points to priority queue 1 for UNI *N*, then it implicitly refers to priority queue 1 for all affected UNIs. + +The multicast GEM IW TP ME is provisioned with the following considerations. + +- The IW option attribute should be set to zero, indicating a "don't care". + +- The service profile pointer attribute is set to zero and not used. +- The IW TP pointer attribute is set to zero and not used. +- The PPTP counter attribute is set to 0xFF and not used. +- The GAL profile pointer and GAL loopback configuration attributes are set to zero and not used. + +The GEM IW TP ME that is used for incidental broadcast is provisioned with the following considerations. + +- The IW option attribute should be set to 6 to indicate broadcast. +- The service profile pointer attribute should be set to zero. +- The IW TP pointer attribute should be set to zero. +- The GAL profile pointer attribute should be set to zero. +- The GAL loopback configuration attribute should be ignored. + +#### II.1.3.1.1.2 Message flows + +Figure II.1.3.1.1.2-1 shows the message flow used to add multicast or incidental broadcast to the model. + +![Sequence diagram showing message flows between OLT and ONU for data plane provisioning. The diagram is split into two sections. The top section shows the flow for a single GEM port instance, involving Create (GEM port network CTP), Create (GEM interworking TP or multicast GEM interworking TP), Create (MAC bridge port config data), and Create (VLAN tagging filter data) messages. The bottom section shows the flow for multiple bridges, involving Create (GEM port network CTP), Create (MAC bridge port config data), Create (VLAN tagging filter data), and Create (GEM interworking TP) messages. Brackets on the right indicate the scope of each message: 'Once per GEM port instance', 'Once per bridge', and 'Or multicast GEM interworking TP'.](6c097fd262c8aa165ea8137a86b05aa7_img.jpg) + +The diagram illustrates the message exchange between an OLT and an ONU for data plane provisioning. It is divided into two vertical sections. The top section shows the provisioning for a single GEM port instance, with messages: 'Create (GEM port network CTP)', 'Create response', 'Create (GEM interworking TP or multicast GEM interworking TP)', 'Create response', 'Create (MAC bridge port config data)', 'Create response', 'Create (VLAN tagging filter data)', and 'Create response'. Brackets on the right indicate that the first two pairs are 'Once per GEM port instance' and the next two pairs are 'Once per bridge'. The bottom section shows the provisioning for multiple bridges, with messages: 'Create (GEM port network CTP)', 'Create response', 'Create (MAC bridge port config data)', 'Create response', 'Create (VLAN tagging filter data)', 'Create response', 'Create (GEM interworking TP)', and 'Create response'. Brackets on the right indicate that the first three pairs are 'Once per bridge' and the last pair is 'Or multicast GEM interworking TP'. + +G.988(12)\_FII.1.3.1.1.2-1 + +Sequence diagram showing message flows between OLT and ONU for data plane provisioning. The diagram is split into two sections. The top section shows the flow for a single GEM port instance, involving Create (GEM port network CTP), Create (GEM interworking TP or multicast GEM interworking TP), Create (MAC bridge port config data), and Create (VLAN tagging filter data) messages. The bottom section shows the flow for multiple bridges, involving Create (GEM port network CTP), Create (MAC bridge port config data), Create (VLAN tagging filter data), and Create (GEM interworking TP) messages. Brackets on the right indicate the scope of each message: 'Once per GEM port instance', 'Once per bridge', and 'Or multicast GEM interworking TP'. + +**Figure II.1.3.1.1.2-1 – Data plane provisioning** + +#### II.1.3.1.2 Multiple UNI OMCI provisioning model + +Figure II.1.3.1.2-1 is the relationship diagram for multicast and incidental broadcast in an ONU with multiple UNIs. The only notable difference between Figure II.1.3.1.2-1 and the model of Figure II.1.3.1.1-1 is that the multicast GEM port and the incidental broadcast GEM port are associated with multiple bridges, thereby sharing a single multicast or broadcast flow across multiple UNIs. + +The operation of the model is functionally identical to that described in clause II.1.3.1.1. + +![A complex block diagram titled 'Multi-UNI L2-OCM with multicast'. It shows two parallel processing paths for network traffic from different User Network Interfaces (UNIs). The top path starts with UNI-G and PPTP Ethernet UNI connected to priority queues A1-A4 (downstream). These queues feed into a central MAC bridge service profile. The bottom path does the same with priority queues B1-B4. Both paths include components like 'Ext VLAN tag operation config data', 'Multicast operations profile', 'Multicast subscriber config info', 'VLAN tagging filter', 'MAC bridge port config data', '802.1p mapper service profile', 'GEM interworking TP', 'Traffic descriptor (downstream/upstream)', 'PQ' (Priority Queue) identifiers, and 'GEM port network CTP'. The final output on the right includes 'T-CONT' blocks and upstream priority queues. Some traffic descriptors point to 'null'.](3600801fb4c34c9aa22b834d51213c2e_img.jpg) + +The diagram illustrates the architecture for Multi-UNI L2-OCM with multicast. It features two primary input sections on the left: one for UNI-G and PPTP Ethernet UNI (top) and another for UNI-G and PPTP Ethernet UNI (bottom). Each section includes four priority queues (A1-A4 or B1-B4) for downstream traffic. These queues are connected to a central MAC bridge service profile. Above the top MAC bridge service profile are 'Multicast operations profile' and 'Multicast subscriber config info'. Below the bottom MAC bridge service profile are 'Multicast subscriber config info' and 'Multicast operations profile'. Both MAC bridge service profiles are connected to a series of processing blocks: 'MAC bridge port config data', 'VLAN tagging filter', '802.1p mapper service profile', 'GEM interworking TP', 'Traffic descriptor (downstream)', 'PQ' (Priority Queue) identifiers (e.g., PQ A1, PQ B1), 'Traffic descriptor (upstream)', and 'GEM port network CTP'. The top path's GEM port network CTP blocks lead to 'T-CONT' blocks and upstream priority queues (PQ 1, PQ 2, PQ 3, PQ 4, PQ Ay, PQ Ax). The bottom path's GEM port network CTP blocks lead to 'T-CONT' blocks and upstream priority queues (PQ 1, PQ 2, PQ 3, PQ 4). Some traffic descriptors in the middle of the diagram point to 'null'. + +A complex block diagram titled 'Multi-UNI L2-OCM with multicast'. It shows two parallel processing paths for network traffic from different User Network Interfaces (UNIs). The top path starts with UNI-G and PPTP Ethernet UNI connected to priority queues A1-A4 (downstream). These queues feed into a central MAC bridge service profile. The bottom path does the same with priority queues B1-B4. Both paths include components like 'Ext VLAN tag operation config data', 'Multicast operations profile', 'Multicast subscriber config info', 'VLAN tagging filter', 'MAC bridge port config data', '802.1p mapper service profile', 'GEM interworking TP', 'Traffic descriptor (downstream/upstream)', 'PQ' (Priority Queue) identifiers, and 'GEM port network CTP'. The final output on the right includes 'T-CONT' blocks and upstream priority queues. Some traffic descriptors point to 'null'. + +G.988(12)\_FII.1.3.1.2-1 + +Figure II.1.3.1.2-1 – Multi-UNI L2-OCM with multicast + +### II.1.3.2 Control plane + +Implementation of traditional multicast services also requires support for IGMP on the control plane. The multicast subscriber config info ME and the multicast operations profile ME are used to provision this support. As shown in Figure II.1.3.1.1-1, these MEs are associated with the MAC bridge port config data ME on the UNI side of the OMCI model. The following considerations should be used when provisioning these MEs. + +- Permitting multicast on a subscriber UNI does not require the existence of a multicast subscriber config info ME. The default action for a bridge port and associated UNI is to allow the forwarding of frames in the multicast address range. If desired, the blocking of frames in the multicast address range is achieved through the use of the MAC bridge port filter table data ME or MAC bridge port filter pre-assign table ME. +- The dynamic access control list table and static access control list table attributes of the multicast operations profile ME include fields for GEM port and VLAN. These should be provisioned consistently with the multicast flow through its GEM port network CTP and possible VLAN tagging filters. The consequence of inconsistent provisioning is undefined. +- The ME type attribute of the multicast subscriber config info ME should be set to zero to indicate an association with a MAC bridge port config data ME. +- The IGMP version attribute of the multicast operations profile ME should be set to 3 to indicate that the ONU will be using IGMP v3, as required by [b-BBF TR-156]. +- A bandwidth-based multicast SLA can be implemented using the max multicast bandwidth and bandwidth enforcement attributes in the multicast subscriber config info ME in conjunction with the imputed group bandwidth field of the dynamic access control list table in the multicast operations profile ME. + +Support of multicast preview or paid preview functions also requires configuration in the control plane. The multicast subscriber config info ME is used to provision this support, including the forwarding of preview groups to UNIs when allowed, and otherwise blocking them. + +## II.2 Dual-managed ONUs + +In many cases, the ONU is physically separated from the equipment connected at the ultimate UNI, and the ONU is managed via the OMCI, while the UNI equipment is managed by other means. For example, the ONU may be connected to an RG via an Ethernet or xDSL interface, with the ONU managed by the OMCI and the RG managed by [BBF TR-069]/[BBF TR-369]. As another example, the ONU in a PON-fed digital subscriber line access multiplexer (DSLAM) may be connected to the DSLAM via an Ethernet interface, with the ONU managed by the OMCI and the DSLAM managed by the SNMP. In these examples, the demarcation point between the two management domains is clear: it is the Ethernet interface. + +However, there are cases where the ONU and the UNI equipment are physically integrated into the same device, and there may not be a physical interface between the two. A dual-managed ONU is defined as two management domains that may control the same physical device. The VEIP ME is the data plane demarcation point between the two management domains, with the OMCI managing everything from the VEIP to the ANI. The management protocol on the other side is not specified. + +Figure II.2-1 shows an OMCI model for a dual-managed ONU/RG, which is an extension of the layer 2 service in clause II.1. There are several important features of this model as follows. + +- 1) As with a physical Ethernet, multiple traffic classes can flow across the virtual Ethernet interface, and each traffic class has an associated priority queue. One implication of this is that extra work may be involved to multiplex/de-multiplex data on both sides of the VEIP. For example, in the upstream direction, the RG conceptually separates traffic by class for queueing and scheduling, then merges all classes into a single stream to pass through the VEIP; the ONU again separates traffic by class to direct to the appropriate upstream queue. + +- 2) The same number of virtual Ethernet interfaces are used as there would be physical Ethernet interfaces between the OMCI domain and the non-OMCI domain if the domains existed on separate devices. For example, there is typically one virtual Ethernet interface per RG. +- 3) The virtual Ethernet interface represents the termination of the ONU data plane, whereas the associated IP host config (IPHC) data ME represents the termination of the ONU management plane. The IPHC is the container for the IP address, mask, gateway and DNS information in the OMCI domain, and in the dual-managed ONU, it may also be used to establish or determine the same information in the non-OMCI domain. For a detailed discussion of IPHC provisioning, refer to clause II.4. + +The IPHC is conditionally required for the dual-managed ONU, depending on the IP stack configuration in the integrated device. Three configurations are possible as follows. + +- a) Dual stack, where each management domain contains a unique IP stack. An IPHC is present for OMCI use if the ONU supports native IP-based services such as VoIP or IP pseudo-wire. A separate IPHC exists for the non-OMCI management domain if IP connectivity is to be provided by the OMCI. + - b) Single stack, shared between the two domains. An IPHC exists if either the OMCI domain provides native IP-based services or if the non-OMCI domain requires the OMCI to set up its IP connectivity. + - c) A single stack, used only by the non-OMCI domain. This case requires an IPHC only if the non-OMCI domain needs the OMCI to establish its IP connectivity. +- 4) The presence of the virtual Ethernet interface ME provides an unambiguous way for the ONU to represent its nature to the OLT during the OMCI MIB discovery process. +- 5) Not more than one GSP may be created by the OLT per VEIP. The GSP provides a way for the OLT to discover the status and configuration information of a non-OMCI management domain within an ONU. This ME contains two table attributes: status document table and configuration document table. The OLT reads these tables to obtain an XML representation of the non-OMCI management domain status and configuration. Whenever the text in this table changes, and after a soak interval, the ONU issues an AVC to the OLT. The rate at which AVCs are issued is controlled by the AVC rate control attribute. +- 6) The ONU automatically creates a UNI-G for each VEIP. +- 7) The ONU automatically creates physical ports (PPTPs) and their associated UNI-Gs that are visible and manageable only via the OMCI. As an option, the ONU may also create PPTP/UNI-G pairs that are either dedicated to a non-OMCI domain or that may flexibly be assigned to either management domain by the OLT. If the ONU does not automatically create such MEs, they must be created by other means, which lie beyond the scope of this Recommendation. The OLT cannot create them via the OMCI. + +The capability of the UNI-G/PPTP is advertised by the ONU in the management capability attribute of the UNI-G ME. If a UNI-G/PPTP is assignable to a specific domain, the OLT can set the UNI-G non-OMCI management identifier to assign the PPTP/UNI-G to a non-OMCI domain. + +The dual-managed ONU OMCI data plane model is provisioned in the same way as exemplified in clause II.1.2. + +![Figure II.2-1 – Dual-managed ONU model. This is a complex block diagram showing the internal architecture of a Dual-managed ONU. On the left, a 'Generic status portal' connects to a 'Virtual Ethernet interface pt'. This interface is linked to four 'Priority queue' blocks (A1, A2, A3, A4) labeled '(downstream)'. Below the interface, 'TCP/UDP config data' and 'IP host config data' are shown. The 'Virtual Ethernet interface pt' also connects to a 'MAC bridge service profile' block. This profile is connected to several 'MAC bridge port config data' blocks. One 'MAC bridge port config data' block connects to an 'Ext VLAN tag operation config data' block, which in turn connects to a 'Multicast operations profile' and a 'Multicast subscriber config info' block. Another 'MAC bridge port config data' block connects to a 'VLAN tagging filter' block, which connects to an '802.1p mapper service profile' block. This profile connects to a 'GEM interworking TP' block, which then connects to a 'GEM port network CTP' block. This CTP block is associated with 'Traffic descriptor (downstream)', 'PQ A1', 'Traffic descriptor (upstream)', and 'T-CONT' blocks. The diagram continues with multiple similar paths for priority queues A2, A3, A4, Ay, and n. For PQ A4, the 'GEM port network CTP' block is associated with 'null'. For PQ Ay, the 'GEM port network CTP' block is associated with 'null'. For PQ n, the 'GEM port network CTP' block is associated with 'PQ n'. There are also 'UNL-G' and 'MAC bridge service profile' blocks. The diagram is labeled 'G.988(12)_FII.2-1' in the bottom right corner.](3f5a5593228cdb8d717ce04dc85d73a8_img.jpg) + +Figure II.2-1 – Dual-managed ONU model. This is a complex block diagram showing the internal architecture of a Dual-managed ONU. On the left, a 'Generic status portal' connects to a 'Virtual Ethernet interface pt'. This interface is linked to four 'Priority queue' blocks (A1, A2, A3, A4) labeled '(downstream)'. Below the interface, 'TCP/UDP config data' and 'IP host config data' are shown. The 'Virtual Ethernet interface pt' also connects to a 'MAC bridge service profile' block. This profile is connected to several 'MAC bridge port config data' blocks. One 'MAC bridge port config data' block connects to an 'Ext VLAN tag operation config data' block, which in turn connects to a 'Multicast operations profile' and a 'Multicast subscriber config info' block. Another 'MAC bridge port config data' block connects to a 'VLAN tagging filter' block, which connects to an '802.1p mapper service profile' block. This profile connects to a 'GEM interworking TP' block, which then connects to a 'GEM port network CTP' block. This CTP block is associated with 'Traffic descriptor (downstream)', 'PQ A1', 'Traffic descriptor (upstream)', and 'T-CONT' blocks. The diagram continues with multiple similar paths for priority queues A2, A3, A4, Ay, and n. For PQ A4, the 'GEM port network CTP' block is associated with 'null'. For PQ Ay, the 'GEM port network CTP' block is associated with 'null'. For PQ n, the 'GEM port network CTP' block is associated with 'PQ n'. There are also 'UNL-G' and 'MAC bridge service profile' blocks. The diagram is labeled 'G.988(12)\_FII.2-1' in the bottom right corner. + +Figure II.2-1 – Dual-managed ONU model + +## II.3 Traffic management + +### II.3.1 Requirements and techniques + +#### II.3.1.1 Introduction + +G-PON contains a number of features related to QoS, such as policing, shaping, queueing and scheduling. These features can be applied to a variety of different QoS architectures such as diffserv, metro Ethernet and [b-BBF TR-101]. This clause exemplifies how to map G-PON QoS features to diffserv or metro Ethernet services. + +### II.3.1.2 Diffserv over G-PON + +[b-IETF RFC 2475] outlines the diffserv, or differentiated services, model for providing QoS. The diffserv model specifies that traffic is classified and conditioned (metered, shaped, policed or re-marked) at the edge of the QoS domain and then queued and scheduled for forwarding at each node in the interior of the QoS domain based on the per-hop behaviour of the class. This relative QoS on a per-hop basis instead of a network-wide basis is a fundamental property of the diffserv model. + +[b-IETF RFC 2475] defines the basic framework for diffserv; additional RFCs define the behaviour of the most commonly used traffic classes, EF in [IETF RFC 3246] and [b-IETF RFC 3247], and AF in [IETF RFC 2597]. + +AF includes the concept of drop precedence, by which traffic can be admitted and marked in such a way that traffic will be dropped in a prescribed precedence within a class when congestion occurs. AF defines four classes, each with three drop precedence levels. With AF, it is important that packets within a class not be reordered. + +To implement diffserv, traffic must be classified and policed/marked at the ingress and egress of the QoS domain. A marker function that can be used for diffserv is specified in [b-IETF RFC 4115], the two-rate three colour marker system (trTCM). The trTCM marker function has two associated rates, the CIR and the EIR. A dual token bucket algorithm is used for this colour marking. If the packet length is less than the number of tokens in the committed token bucket, the packet is declared green; else if the packet length is less than the number of tokens in the excess token bucket, the packet is declared yellow; otherwise, the packet is declared red. These three colours are mapped to the three drop precedences – as an example, green traffic could be marked with drop precedence 1, with yellow traffic marked with either drop precedence 2 or 3. During times of congestion, the ONU drops yellow packets with a higher probability than green packets. In G-PON, the PIR is equal to the sum of the CIR and EIR. + +EF is intended for constructing low-latency and low-loss services, in that it is assumed that packets marked with the EF class can pre-empt other traffic within limits. EF can be implemented with a simple priority queue, where the output of the EF priority queue is given priority over other queues, but where the input to the EF priority queue is governed by a token bucket to prevent starvation of the other queues. As with AF, it is important that EF class packets not be reordered. + +Assuming the domain edge is the ONU, each diffserv CoS should be assigned its own T-CONT. In this way, the OLT can schedule grants to provide fair access to the shared G-PON bandwidth. For a given ONU, flows from different users but within the same CoS should be policed separately and then placed in the same queue. OLTs should assign bandwidth using the extended bandwidth assignment model for DBA as described in the respective TC layer specification. T-CONTs containing flows from the same class but from different ONUs should be assigned the same priority at the OLT, but should be assigned weights proportional to the cumulative data rate of those flows. + +Figure II.3.1.2-1 shows an example of the distribution of upstream functionality between the ONU and the OLT for a diffserv architecture. + +![Block diagram example of diffserv upstream QoS for G-PON. The diagram shows traffic flow from the User facing side (right) through Tag/classify/map blocks for different traffic classes (EF, AF3, AF2, BE) to Mark/police blocks, then to GEM ports, ONUs, T-CONTs (A, B, C, D), WFQ schedulers, and finally to the Network facing side (left) via a Strict priority scheduler. The Network facing side is labeled with P_i and 1, 2, 3.](12957cc44ed694f84719f5792dc73ed3_img.jpg) + +The diagram illustrates the upstream QoS architecture for G-PON. On the right, the 'User facing side' shows multiple users (User 1 to User N) providing traffic for different classes: EF (Expedited Forwarding), AF3 (Assured Forwarding 3), AF2 (Assured Forwarding 2), and BE (Best Effort). This traffic passes through a 'Tag/classify/map' block, then a 'Mark/police' block for each class. The traffic is then aggregated into 'GEM ports', which connect to 'ONUs'. From the ONUs, traffic is sent to 'T-CONT' units (labeled A, B, C, and D). Each T-CONT is associated with a 'WFQ sched' (Weighted Fair Queueing scheduler). The WFQ schedulers output traffic to a 'Strict priority sched' block on the left, which then outputs to the 'Network facing side'. The Network facing side is labeled with $P_i$ and numbered 1, 2, and 3. A dashed vertical line separates the ONU side from the GEM port side. The diagram is labeled 'G.988(12)\_FII.3.1.2-1' at the bottom right. + +Block diagram example of diffserv upstream QoS for G-PON. The diagram shows traffic flow from the User facing side (right) through Tag/classify/map blocks for different traffic classes (EF, AF3, AF2, BE) to Mark/police blocks, then to GEM ports, ONUs, T-CONTs (A, B, C, D), WFQ schedulers, and finally to the Network facing side (left) via a Strict priority scheduler. The Network facing side is labeled with P\_i and 1, 2, 3. + +NOTE 1 – Weighted fair queueing (WFQ) weights should be configurable. + +NOTE 2 – WFQ and strict scheduling implemented with extended bandwidth assignment DBA. + +**Figure II.3.1.2-1 – Block diagram example of diffserv upstream QoS for G-PON** + +The L2-OCM provisioning model defined in clause II.1 supports diffserv. In this model, the traffic descriptor ME is used to specify the treatment of each traffic class in the ONU. The following considerations should be used when provisioning the traffic descriptor. + +- For EF traffic, the CIR and PIR attributes should be set to the CIR of the EF traffic profile. +- For AF traffic, the CIR attribute should be set to the CIR of the AF traffic profile. The PIR attribute should be set to the sum of the CIR and EIR of the AF traffic profile. +- For BE traffic, the CIR attribute should be set to the CIR of the BE traffic. The PIR attribute should be set to the sum of the CIR and EIR of the BE traffic profile. +- The colour mode attribute should be set to 1 to indicate a colour aware traffic flow. +- The ingress colour marking and egress colour marking attributes should be set to 7 to indicate DSCP AF drop precedence marking. + +### II.3.1.3 Metro Ethernet over G-PON + +[b-MEF 10.2] describes an Ethernet virtual service (EVS), which is a layer 2 connection between customer edge devices. In the MEF model, the edge of the QoS domain is defined at the ONU UNI, where the marking/policing function is carried out. [b-MEF 10.2] does not define any specific per-hop behaviour. Instead, it focuses on end-to-end service level specifications in terms of delay, delay variation and packet delivery ratio. In this architecture, it is assumed that the UNI is a customer-facing [IEEE 802.3] (Ethernet) interface on the ONU. + +The traffic management defined by [b-MEF 10.2] employs a two-rate, three-colour policer, which is identical to [b-IETF RFC 4115] if the MEF 10.2 variable CF is set to 0. The two rates are CIR and EIR, and are defined for both ingress frames and egress frames. If the frame (ingress or egress) length is less than the number of tokens in the committed token bucket, the frame is declared green; else if the frame length is less than the number of tokens in the excess token bucket, the frame is declared yellow; otherwise, the frame is declared red. This policing takes place at the UNI. + +According to [b-MEF 10.2], traffic marked green is to be delivered according to the service level specification, traffic marked yellow may be delivered, but is not bound to the service level specification, and traffic marked red is to be dropped. + +[b-MEF 10.2] does not specify the means by which an Ethernet virtual connection (EVC) is designated within a service provider's network. However, this appendix recommends using [IEEE 802.1ad] double VLAN tags: C tags for customer use and S tags for service provider use. + +At the UNI, a VLAN S-tag is added to or translated on ingress frames (from the customer) and P bits are set appropriately. The S tag is removed or translated from egress frames (towards the customer). The mapping to S tags should be one per EVC. + +### II.3.1.3.1 Provisioning considerations + +Each S-tag P-bit value (CoS) should be assigned its own T-CONT. In this way, the OLT can schedule grants to provide fair access to the shared G-PON bandwidth. For a given ONU, flows from different users but within the same CoS should be policed separately and then placed in the same queue. OLTs should assign bandwidth using the extended bandwidth assignment model for DBA (Ref: Respective TC layer specification). At the OLT, T-CONTs containing flows from the same class but from different ONUs should be assigned the same priority, but should be assigned weights proportional to the cumulative data rate of those flows. + +The DEI bit should indicate that yellow frames are eligible for discard. Red frames should be dropped in the ONU and never forwarded to the OLT. It is important that frames not be reordered. Therefore, all traffic for a given CoS (both green and yellow) must be kept in a single logical queue. During times of congestion, the ONU will drop yellow packets with a higher probability than green packets. + +The L2-OCM provisioning model defined in clause II.1 supports [b-MEF 10.2]. In this model, the traffic descriptor ME is used to describe the behaviour of each traffic class in the ONU. The following considerations should be used when provisioning the traffic descriptor. + +- For each EVC, the CIR and PIR attributes should be set to the appropriate values for that EVC. +- The colour mode attribute should be set to 1 to indicate a colour-aware traffic flow. +- The ingress colour marking and egress colour marking attributes should be set to 2 to indicate DEI drop precedence marking. + +### II.3.2 Traffic management in [b-BBF TR-156] + +This clause is a high-level mapping from the traffic management text of [b-BBF TR-156] to the OMCI. In this clause, numbers in brackets (e.g., [R-x]) indicate the corresponding requirement number in [b-BBF TR-156]. + +NOTE 1 – The [b-BBF TR-156] text is paraphrased in this clause. In the case of inconsistencies between this clause and [b-BBF TR-156], [b-BBF TR-156] takes precedence. + +NOTE 2 – The details in [b-BBF TR-156] refer to [ITU-T G.984.x]. The same requirements largely pertain to subsequent systems. + +In this clause, traffic management is defined to comprise the following components: 1) traffic classification; 2) rate limiting; 3) queueing; 4) scheduling; and 5) T-CONT assignment. [b-BBF TR-156] assumes that there will always be a broadband network gateway (BNG) and possibly an Ethernet aggregation node on the network side of an OLT, and an RG on the user side of an ONU. Although the models are similar, this clause does not consider G-PON-fed DSLAMs. + +The high-level architectural view considered in this clause is given in Figure II.3.2-1 (from [b-BBF TR-156]). The OLT and ONU are regarded as a distributed access node. It is possible for the ONU and RG to be integrated. + +![Figure II.3.2-1 – High-level architecture diagram showing the flow of traffic from multiple network service providers (NSPs) and an access service provider (ASP) through a regional broadband network and an access network to a customer premises network (CPN).](d4398b19d03756ae1dab309a8969adf1_img.jpg) + +The diagram illustrates the high-level architecture of a network. On the left, four external entities (NSP1/BNG, NSP2, NSP3, and ASP1) are connected via an A10 interface. NSP1/BNG connects via Ethernet, NSP2 via L2TP, NSP3 via IP – QoS, and ASP1 via IP – QoS. These connections lead into a 'Regional broadband network' which contains an 'L2TS' and an 'IP' node. The 'Regional broadband network' is connected to an 'Access network'. The 'Access network' contains a 'BNG', an 'Eth agg', an 'OLT', an 'ODN', and an 'ONU'. The 'OLT' is connected to the 'Eth agg', and the 'ODN' is connected to the 'OLT'. The 'ODN' is further connected to the 'ONU'. The 'ONU' is connected to a 'Customer prem network' which contains an 'RG' and two 'User' nodes (User1 and User2). The 'RG' is connected to the 'ONU' and the 'User' nodes. The 'Customer prem network' is also connected to the 'Access network' via a 'U' and 'T' interface. The diagram is labeled with 'G.988(12)\_FII.3.2-1' in the bottom right corner. + +Figure II.3.2-1 – High-level architecture diagram showing the flow of traffic from multiple network service providers (NSPs) and an access service provider (ASP) through a regional broadband network and an access network to a customer premises network (CPN). + +**Figure II.3.2-1 – High-level architecture** + +### II.3.2.1 Traffic classification + +Downstream, GEM ports are used to differentiate between traffic classes for a particular user port. Each GEM port identifies a specific traffic class going to a specific UNI on a specific ONU. Therefore, a given GEM port carries no more than one traffic class [R-6, R-7]. + +In the upstream direction, the ONU must support deriving VLAN priority (P-bit) markings based on the user port, VID, received P-bits and Ethertype [R-48], and the ONU should support deriving P bits based on user port, VID and received DSCP value [R-49]. The ONU must support mapping traffic flows into GEM ports based on the user port, VLAN ID or VLAN priority [R-51]. + +The OLT and ONU must support at least four traffic classes [R-46], and should support at least six [R-47]. + +### II.3.2.2 Rate limiting + +The ONU and OLT must support rate limiting of IGMP messages received from user ports on a multicast VLAN [R-87]. + +The ONU and OLT must support rate limiting of CFM (connectivity fault management) Ethernet OAM messages arriving on a user port; the rate must be configurable per port [b-BBF TR-101] [R-268]. CFM provisioning is symmetric: the expected message receive rate is equal to the message transmit rate. High message rates may interfere with traffic or overload the ONU processor and are to be used judiciously. + +### II.3.2.3 Queueing + +During periods of queue congestion, the ONU and OLT must be capable of dropping (not queueing) packets marked as drop eligible, with a probability higher than that of packets not marked as drop eligible. Drop eligibility (drop precedence) can be indicated either by VLAN priority bits [R-54], or by the DEI bit (802.1ad) [R-55]. These packets may have drop eligibility marked externally (e.g., by the BNG or RG). + +The OLT must support one downstream queue per traffic class per PON, and at least four traffic classes [R-58]. Likewise, the OLT must provide one upstream queue per network-facing port for each of at least four traffic classes [R-66]. The OLT should support six traffic classes in each direction [R-62], [R-68]. + +The ONU must support a downstream queue per user-facing port for each of at least four traffic classes [R-56]. The ONU must provide an upstream queue for each of at least four traffic classes [R-57]. The ONU should support at least six traffic classes [R-60], [R-61]. + +The OLT must and the ONU should support setting the maximum size/depth of all queues [R-73]. + +### II.3.2.4 Scheduling + +At a minimum, [b-BBF TR-156] requires strict priority scheduling among queues. In the downstream direction, the OLT must support strict priority scheduling among at least four queues for each PON [R-63], and the ONU must support strict priority scheduling among at least four queues for each user-facing port [R-63]. In the upstream direction, the OLT must support strict priority scheduling among at least four queues for each network-facing port [R-70]. + +Weighted scheduling among queues is an objective. The OLT and ONU should support scheduling of queues according to their assigned priority and weight, with the following conditions: 1) multiple queues may be assigned to the same priority; 2) queues assigned the same priority must be scheduled according to a weighted algorithm; and 3) weights must be assigned through provisioning [R-65], [R-72]. Non-empty queues at the same priority receive capacity in proportion to their weights. + +The OLT must support the basic traffic descriptor parameters RF, RA, RM, and $\chi_{AB}$ as specified in [ITU-T G.984.3] [R-44]. The OLT must support the extended traffic descriptor parameters $P_i$ and $\omega_i$ as specified in [ITU-T G.984.3] [R-45], which are used to implement the strict priority and weighted scheduling of T-CONTs. These parameters must be configurable [R-44], [R-45]. The OLT must support T-CONT types 1, 2, 3 and 4 [R-59]. + +NOTE – T-CONT type numbering is purely a documentation convenience. In actual use, the T-CONT type is not represented by any provisioned attribute on the PON. + +The ONU-G ME must at least support traffic management option 0 (priority controlled). + +### II.3.2.5 T-CONT support + +By providing a T-CONT for each traffic class, the ONU must support four upstream traffic classes [R-67], and should support six [R-69]. + +### II.3.2.6 OMCI model + +The following OMCI MEs and attributes support the functionality of this clause. + +#### **Priority queue** + +- **Related port:** For upstream, the first 2 bytes point to the associated T-CONT, and the last 2 bytes are "don't care" ([b-BBF TR-156] specifies only one priority queue for each T-CONT, which performs no scheduling). For downstream, the first 2 bytes point to the slot and port of the specific downstream port, and the last 2 bytes indicate the strict priority associated with this priority queue. +- **Traffic scheduler pointer:** Set to the default null pointer. +- **Weight:** For upstream, this attribute should remain at the default value of 1 ([b-BBF TR-156] specifies only one priority queue for each T-CONT, which performs no scheduling). For downstream, this attribute should be set to the weight associated with this priority queue, or set to 1 if weighted scheduling is not used. +- **Packet drop queue thresholds:** These are used to implement the BBF TR-156 drop eligibility (drop precedence) requirements. + +Packet drop max\_p + +Queue drop w\_q + +- **Drop precedence colour marking:** Must be set either to one of the PCP modes or to DEI. + +#### **ONU-G** + +- **Traffic management option:** Read-only, defined by the ONU architecture. 0 indicates priority-controlled mode. Even if the value is 2, indicating the ability to perform in either priority or rate-controlled mode, [b-BBF TR-156] uses only the priority-controlled mode. + +## T-CONT + +- Policy: This value is a "don't care." [b-BBF TR-156] specifies only one priority queue for each T-CONT, which performs no scheduling. + +Figures II.3.2.6-1 and II.3.2.6-2 give examples of the downstream and upstream traffic management functionality. + +![Figure II.3.2.6-1 – Downstream functionality example. This diagram shows the flow of data from an OLT to multiple ONUs. On the OLT side, an external interface 'V' connects to a 'Classifier'. The 'Classifier' directs traffic into multiple queues, one for each PON (PON 1, PON n). These queues feed into a 'Scheduler'. The 'Scheduler' outputs traffic through a shared 'S/R' (Send/Receive) interface. On the ONU side, the traffic is received through the 'R/S' (Receive/Send) interface and is 'Assign to queues according to GEM port'. Each ONU (ONU-1, ONU n) has its own set of queues (UNI 1, UNI n) that feed into its own 'Scheduler', which then outputs to the external interface 'U'.](aefc48058685868efc2e0a1a581a991e_img.jpg) + +Figure II.3.2.6-1 – Downstream functionality example. This diagram shows the flow of data from an OLT to multiple ONUs. On the OLT side, an external interface 'V' connects to a 'Classifier'. The 'Classifier' directs traffic into multiple queues, one for each PON (PON 1, PON n). These queues feed into a 'Scheduler'. The 'Scheduler' outputs traffic through a shared 'S/R' (Send/Receive) interface. On the ONU side, the traffic is received through the 'R/S' (Receive/Send) interface and is 'Assign to queues according to GEM port'. Each ONU (ONU-1, ONU n) has its own set of queues (UNI 1, UNI n) that feed into its own 'Scheduler', which then outputs to the external interface 'U'. + +Figure II.3.2.6-1 – Downstream functionality example + +![Figure II.3.2.6-2 – Upstream functionality example. This diagram shows the flow of data from multiple ONUs to an OLT. On the ONU side, external traffic from interface 'U' is processed by a 'Classifier' and then enters a queue. Each ONU (ONU-1, ONU n) has a queue that feeds into a summation node (represented by a circle with a plus sign). The outputs of these nodes are labeled as T-CONT A, T-CONT B, T-CONT C, and T-CONT D. These T-CONTs are transmitted through a shared 'S/R' (Send/Receive) interface. On the OLT side, the traffic is received through the 'R/S' (Receive/Send) interface, passes through another set of summation nodes, and then enters a 'Scheduler', which finally outputs through the external interface 'V'.](e44e80a98e0fc0e463cf1131013eb89e_img.jpg) + +Figure II.3.2.6-2 – Upstream functionality example. This diagram shows the flow of data from multiple ONUs to an OLT. On the ONU side, external traffic from interface 'U' is processed by a 'Classifier' and then enters a queue. Each ONU (ONU-1, ONU n) has a queue that feeds into a summation node (represented by a circle with a plus sign). The outputs of these nodes are labeled as T-CONT A, T-CONT B, T-CONT C, and T-CONT D. These T-CONTs are transmitted through a shared 'S/R' (Send/Receive) interface. On the OLT side, the traffic is received through the 'R/S' (Receive/Send) interface, passes through another set of summation nodes, and then enters a 'Scheduler', which finally outputs through the external interface 'V'. + +Figure II.3.2.6-2 – Upstream functionality example + +### **II.3.3 Beyond [b-BBF TR-156]** + +There are non-BBF TR-156 applications where it is desirable to have multiple queues per T-CONT and to have scheduling between these queues. One example would be the multiple dwelling unit (MDU) ONU, where there are multiple UNIs, each of which serves a different subscriber. The service provider may wish to configure the ONU such that no single UNI within the ONU consumes more than its fair share of the bandwidth assigned to a given traffic class. This could be done for a given traffic class by giving each UNI a separate queue, then using some form of weighted scheduling (like WRR) to schedule traffic from the queues into the T-CONT for that traffic class. + +Another example would be where the service provider assigns a VLAN to a T-CONT, but wishes to give a different priority to different flows within that T-CONT. This could be done by mapping specific P-bit values within that VLAN to different queues, then using strict priority to schedule traffic from the queues into the T-CONT for that VLAN. As a specific example, P-bits value 1 could be mapped to one queue, P-bits value 3 could be mapped to another queue, and strict priority could be used to schedule between the two queues. From the OLT's point of view, all traffic in this T-CONT would be a single traffic class that could be governed by a VLAN-level SLA. + +This clause describes the best practice for implementing scheduling among multiple queues associated with a given T-CONT. Only a single level of scheduling is considered; hierarchical scheduling is not considered. The clause considers only two scheduling disciplines for each multi-queue T-CONT. + +- 1) **Strict priority scheduling:** The queues are served in the specified priority order. This corresponds to the strict priority value of the scheduling policy attribute. +- 2) **Weighted scheduling:** Back-logged (non-empty) queues are served in proportion to their specified weights. This corresponds to the WRR value of the scheduling policy attribute. + +Prior to 2009, the OMCI specified a fixed set of priority queue MEs and traffic scheduler MEs associated with each T-CONT ME, assuming these resources were fixed in the ONU's architecture. In 2009, a flexible means of mapping between queues, schedulers and T-CONTs was added, allowing a pool of queues to be attached to any scheduler and T-CONT in the same slot. Clause II.3.3.1 describes the best practice for using the fixed method. Clause II.3.3.2 describes the flexible alternative. + +For legacy reasons, the fixed method is the default – the ONU must have a factory default configuration of queues/schedulers/T-CONTs that would be usable by an OLT that only supports the fixed method, and the OLT must work with ONUs that only support the fixed method. The flexible method is considered an extension of the fixed method, and may be used when supported by both the ONU (as indicated by the QoS configuration flexibility attribute in the ONU2-G ME) and the OLT. + +#### **II.3.3.1 Default practice – Fixed queue/scheduler/T-CONT** + +The default ONU architecture assumes a fixed set of priority queue MEs and traffic scheduler MEs associated with each T-CONT ME. The pointers between traffic scheduler MEs and T-CONT MEs are fixed, but the priority queue MEs can be provisioned to point either to the associated T-CONT or to one of the associated traffic schedulers. The scheduling policy of each T-CONT ME and each traffic scheduler ME is fixed. It is not assumed that all T-CONTs have the same number of priority queue MEs and traffic scheduler MEs. The OLT must determine the ONU's queue configuration and connect the GEM port network CTP MEs accordingly. + +Not all T-CONTs in an ONU must support these scheduling capabilities. However, in order to be interoperable, any T-CONT that supports the scheduling capabilities of this clause must have at least two priority queue MEs and one of the two following configurations. + +- 1) **Traffic scheduler not present:** Only a single scheduling discipline is supported, as determined by the T-CONT policy attribute. The priority queue MEs are connected directly to the T-CONT ME. + +- 2) Traffic scheduler present: The traffic scheduler ME and T-CONT ME must have opposite policy attributes, meaning that one has the strict priority policy and the other has WRR. Both scheduling disciplines are therefore supported. Priority queue MEs can be connected to either the traffic scheduler ME or directly to the T-CONT ME to determine the scheduling discipline. + +Furthermore, to be interoperable, the read-only parameter values described in clauses II.3.3.1.1 and II.3.3.1.2 are required. + +### II.3.3.1.1 ONU provisioning considerations + +The MEs used in this clause for traffic scheduling are the priority queue, traffic scheduler and T-CONT. + +Figure II.3.3.1.1-1 shows an example of a T-CONT with three queues and no traffic scheduler. Each queue is directly connected to the T-CONT ME. The scheduling discipline is determined from the policy attribute of the T-CONT ME, in this case weighted (policy = WRR). + +![Diagram of weighted scheduling with three queues per T-CONT and no traffic scheduler.](8c6b89f73329f48b2300fb82e6c9f8ab_img.jpg) + +The diagram illustrates a traffic scheduling architecture. On the left, three 'GEM port network CTP' blocks are stacked vertically. Each block has an arrow pointing to a corresponding 'Traffic descriptor (upstream)' block and another arrow pointing to a 'Priority queue' block. Each 'Priority queue' block has an arrow pointing to a single 'T-CONT (WRR)' block on the right. The 'Traffic descriptor (upstream)' blocks are positioned above their respective 'GEM port network CTP' blocks, with arrows pointing from the CTP to the descriptor. The 'T-CONT (WRR)' block is the final destination for all three priority queues. A small label 'G.988(12)\_FII.3.3.1.1-1' is located at the bottom right of the diagram. + +Diagram of weighted scheduling with three queues per T-CONT and no traffic scheduler. + +**Figure II.3.3.1.1-1 – Example of weighted scheduling with three queues per T-CONT and no traffic scheduler, queues connected directly to T-CONT** + +Figure II.3.3.1.1-2 shows an example of a T-CONT with four queues and a traffic scheduler. Because each queue is connected to the traffic scheduler, the scheduling discipline is determined from the policy attribute of the traffic scheduler ME, in this case weighted (policy = WRR). + +![Diagram of weighted scheduling with four queues per T-CONT and traffic scheduler. Five GEM port network CTPs are shown. Each CTP has an associated 'Traffic descriptor (upstream)' box and a 'Priority queue' box. Arrows point from each CTP to its descriptor and then to its priority queue. All five priority queues have arrows pointing to a central 'Traffic scheduler (WRR)' box. The WRR box has an arrow pointing to a 'T-CONT (HOL)' box. The label 'G.988(12)_FII.3.3.1.1-2' is at the bottom right.](3de4054a64d656760b2bfd54ed67fb83_img.jpg) + +Diagram of weighted scheduling with four queues per T-CONT and traffic scheduler. Five GEM port network CTPs are shown. Each CTP has an associated 'Traffic descriptor (upstream)' box and a 'Priority queue' box. Arrows point from each CTP to its descriptor and then to its priority queue. All five priority queues have arrows pointing to a central 'Traffic scheduler (WRR)' box. The WRR box has an arrow pointing to a 'T-CONT (HOL)' box. The label 'G.988(12)\_FII.3.3.1.1-2' is at the bottom right. + +**Figure II.3.3.1.1-2 – Example of weighted scheduling with four queues per T-CONT and traffic scheduler, queues connected to traffic scheduler** + +Figure II.3.3.1.1-3 shows an example of a T-CONT with four queues and a traffic scheduler ME. Because each queue is directly connected to the T-CONT ME, the scheduling discipline is determined from the policy attribute of the T-CONT ME, in this case strict priority. + +![Diagram of strict priority scheduling with four queues per T-CONT and traffic scheduler. Five GEM port network CTPs are shown. Each CTP has an associated 'Traffic descriptor (upstream)' box and a 'Priority queue' box. Arrows point from each CTP to its descriptor and then to its priority queue. All five priority queues have arrows pointing directly to a 'T-CONT (HOL)' box. A 'Traffic scheduler (WRR)' box is shown to the left of the T-CONT, with arrows pointing to it from the T-CONT and back to the T-CONT, but it is not connected to the priority queues. The label 'G.988(12)_FII.3.3.1.1-3' is at the bottom right.](1a3360ba1ea104f672cac0b7ce78f3fc_img.jpg) + +Diagram of strict priority scheduling with four queues per T-CONT and traffic scheduler. Five GEM port network CTPs are shown. Each CTP has an associated 'Traffic descriptor (upstream)' box and a 'Priority queue' box. Arrows point from each CTP to its descriptor and then to its priority queue. All five priority queues have arrows pointing directly to a 'T-CONT (HOL)' box. A 'Traffic scheduler (WRR)' box is shown to the left of the T-CONT, with arrows pointing to it from the T-CONT and back to the T-CONT, but it is not connected to the priority queues. The label 'G.988(12)\_FII.3.3.1.1-3' is at the bottom right. + +NOTE – The traffic scheduler performs no function in this example. It is shown to illustrate components that may be present as inbuilt features of the ONU architecture. + +**Figure II.3.3.1.1-3 – Example of strict priority scheduling with four queues per T-CONT and traffic scheduler, queues connected directly to T-CONT** + +## Priority queue ME + +Each priority queue ME has a fixed priority and a configurable weight. The OLT can configure each priority queue ME to either point to the associated traffic scheduler ME or to point directly to the associated T-CONT ME. + +For an upstream queue, the related port attribute is read-only by default and is divided into two parts: 1) the ME ID of the associated T-CONT, and 2) the priority of the queue. To support strict priority scheduling between multiple queues associated with a T-CONT, each queue must have a different priority. + +The weight attribute is RW, and is used to provide weighted scheduling between the queues associated with a T-CONT. Non-empty queues at a given priority receive capacity in proportion to their weights. + +The traffic scheduler pointer attribute is RW and is provisioned to either point to the associated traffic scheduler ME (if present) or to the associated T-CONT ME (null pointer value). The value of this attribute as a function of the desired scheduling discipline is shown in Table II.3.3.1.1-1. During normal operation, either all priority queues associated with a T-CONT should be mapped to the traffic scheduler ME (if present) or all should be mapped to the T-CONT ME. During provisioning, there may be a temporary period where some of the priority queues associated with a T-CONT are mapped to the traffic scheduler and some are mapped to the T-CONT, in which case the ONU's behaviour is undefined. + +The traffic scheduler pointer attribute value is a "don't care" for priority queues that are not in use, i.e., that are not connected to GEM port network CTP MEs. + +**Table II.3.3.1.1-1 – Value of priority queue traffic scheduler pointer attribute to achieve desired scheduling discipline** + +| Desired scheduling discipline | T-CONT policy | Traffic scheduler present? | Traffic scheduler policy | Priority queue traffic scheduler pointer attribute | +|-------------------------------|-----------------|----------------------------|--------------------------|----------------------------------------------------| +| Strict | Strict priority | Don't care | Don't care | T-CONT (null) | +| Strict | WRR | Yes | Strict priority | Traffic scheduler | +| Weighted | WRR | Don't care | Don't care | T-CONT (null) | +| Weighted | Strict priority | Yes | WRR | Traffic scheduler | + +## Traffic scheduler ME + +By default, the traffic scheduler ME has a fixed scheduling policy and fixed pointers and a configurable priority/weight. If the traffic scheduler is present, the following are its attribute settings. Flexible configuration is discussed in clause II.3.3.2. + +- The T-CONT pointer attribute is read-only, and always points to the associated T-CONT. +- The traffic scheduler pointer attribute is read-only and within the scope of this clause is always null, because hierarchical scheduling is out of scope. +- The policy attribute is read-only, and within the scope of this clause is always the "opposite" of the T-CONT ME, i.e., one must be WRR and the other must be strict priority. +- The priority/weight attribute is RW, and within the scope of this clause its value is a "don't care," with a suggested value of zero. + +## T-CONT ME + +The policy attribute is read-only and is always either WRR or strict priority. + +### **II.3.3.1.2 OLT provisioning considerations** + +In the default case, the OLT must learn the priority of each queue and the association between each queue and a T-CONT – priorities and associations cannot be provisioned. If it wishes to support the policy option opposite to that built into the T-CONT itself, the OLT must determine whether a traffic scheduler ME is associated with this T-CONT. The OLT must provision the ONU such that the priority queue/traffic scheduler (if present)/T-CONT ME group is properly connected (via a GEM IW TP and GEM port network CTP) to the appropriate IEEE 802.1p mapper service profile and MAC bridge port config data MEs, and that the queues are connected to the scheduler providing the desired policy. + +#### **Strict priority scheduling** + +If the service requires strict priority scheduling between queues, the OLT must discover a T-CONT ME that has a sufficient number of associated priority queue MEs and either supports the strict priority scheduling policy itself or has a traffic scheduler ME that supports such a policy. For this T-CONT, each required priority queue ME is connected, according to its read-only priority attribute, to the GEM port network CTP associated with that priority. Each required priority queue ME is also connected to the associated T-CONT ME or traffic scheduler ME with strict priority policy, as shown in Table II.3.3.1.1-1. Any unused queues are left unconnected. + +#### **Weighted scheduling** + +If the service requires weighted scheduling between queues, then the OLT must discover a T-CONT ME that has a sufficient number of associated priority queue MEs and either supports the WRR scheduling policy itself or has a traffic scheduler ME that supports such a policy. For this T-CONT, the OLT provisions the weight of each required priority queue ME. Each required priority queue ME is connected to the GEM port network CTP associated with that weight. Each required priority queue ME is connected to the associated T-CONT ME or traffic scheduler ME with WRR policy, as shown in Table II.3.3.1.1-1. Any unused queues are left unconnected. + +### **II.3.3.2 Alternative practice – Flexible queue/scheduler/T-CONT** + +In this alternative method, the QoS configuration flexibility attribute in the ONU2-G ME allows simplification of the provisioning of single-level scheduling. The queues are no longer fixed to a particular T-CONT and set of traffic scheduler MEs, but rather can be flexibly associated with any T-CONT or traffic scheduler ME in the same slot. Furthermore, the scheduling policy for the T-CONT and traffic scheduler MEs is no longer fixed but can be modified during provisioning. Finally, the priority of priority queues may be provisionable. + +#### **II.3.3.2.1 ONU provisioning considerations** + +The MEs used in this clause for traffic scheduling are the ONU2-G, priority queue and the T-CONT. The traffic scheduler ME is not used. + +Figure II.3.3.2.1-1 shows an example of a T-CONT with four flexible queues, each directly connected to the T-CONT ME. As a function of the QoS configuration flexibility attribute in the ONU2-G ME, these queues are assumed to be taken from a pool of queues with flexible pointers, meaning they can point to any traffic scheduler or T-CONT ME in the same slot. The scheduling discipline is selected from the policy attribute of the T-CONT ME, in this example, weighted (policy = WRR). + +![Diagram of an example system of weighted scheduling with four flexible queues. Four GEM port network CTP blocks are on the left, each connected to a 'Traffic descriptor (upstream)' block. Each 'Traffic descriptor' block points to a 'Priority queue' block. The four 'Priority queue' blocks are grouped by a dashed box labeled 'Pool of queues with flexible pointers'. Arrows from each 'Priority queue' point to a 'T-CONT (WRR)' block on the right. A 'Selectable policy' block is also connected to the 'T-CONT (WRR)' block. The diagram is labeled G.988(12)_FII.3.3.2.1-1.](ebb023b9b15a191630034e9e97c8a59f_img.jpg) + +Diagram of an example system of weighted scheduling with four flexible queues. Four GEM port network CTP blocks are on the left, each connected to a 'Traffic descriptor (upstream)' block. Each 'Traffic descriptor' block points to a 'Priority queue' block. The four 'Priority queue' blocks are grouped by a dashed box labeled 'Pool of queues with flexible pointers'. Arrows from each 'Priority queue' point to a 'T-CONT (WRR)' block on the right. A 'Selectable policy' block is also connected to the 'T-CONT (WRR)' block. The diagram is labeled G.988(12)\_FII.3.3.2.1-1. + +**Figure II.3.3.2.1-1 – Example system of weighted scheduling with four flexible queues** + +### ONU2-G ME + +The QoS configuration flexibility attribute of the ONU2-G ME indicates whether the ONU supports flexible priority queue and traffic scheduler pointers, flexible traffic scheduler and T-CONT scheduling policies, or flexible queue priority. Specifically, as follows. + +- 1) If bit 1 is set, the priority queue ME may point to any T-CONT ME in the same slot. +- 2) If bit 2 is set, the priority queue ME may point to any traffic scheduler ME in the same slot. +- 3) If bit 3 is set, the traffic scheduler ME can point to any T-CONT in the same slot. +- 4) If bit 4 is set, the traffic scheduler ME policy attribute is RW. +- 5) If bit 5 is set, the T-CONT ME policy attribute is RW. +- 6) If bit 6 is set, the priority queue ME priority field is RW. + +For the single-level scheduling in the rest of this clause, it is assumed that bits 1, 5 and 6 are set, and bits 2, 3 and 4 are "don't care". + +### Priority queue ME + +Each priority queue ME has a configurable priority and weight. The OLT can configure each priority queue ME to point to any traffic scheduler ME or any T-CONT ME in the same slot. + +The related port attribute is divided into two parts for upstream traffic: 1) the ME ID of the associated T-CONT, which should be set to the desired T-CONT in a given slot; and 2) the priority of the queue. To support strict priority scheduling between multiple queues, each queue must have a different priority. + +The weight attribute is RW, and is used to provide weighted scheduling between the queues associated with a T-CONT. + +The traffic scheduler pointer attribute is RW and is provisioned to either point to the associated traffic scheduler ME or to the associated T-CONT ME (null pointer value). The value of this attribute should be set to zero (null), indicating that this queue is mapped to the T-CONT indicated by the related port attribute. During provisioning, there may be a temporary period where some of the priority queues + +associated with a T-CONT are mapped to a traffic scheduler and some are mapped to the T-CONT, in which case the ONU's behaviour is undefined. The traffic scheduler pointer attribute value is a "don't care" for priority queues that are not in use, i.e., that are not connected to GEM port network CTP MEs. + +#### **T-CONT ME** + +The policy attribute is RW and must be either WRR or strict priority according to the required service. + +##### **II.3.3.2.2 OLT provisioning considerations** + +The OLT selects the desired priority queue MEs from the pool, and connects them to the desired T-CONT. It also sets the policy of this T-CONT to conform to the scheduling policy required by the service. The OLT provisions the ONU such that the priority queue/T-CONT ME group is properly connected (via a GEM IW TP and GEM port network CTP) to the appropriate IEEE 802.1p mapper service profile and MAC bridge port config data MEs. + +##### **Strict priority scheduling** + +If the service requires strict priority scheduling between queues, the OLT selects a T-CONT ME and sets its policy attribute to strict priority. The OLT also selects the required number of priority queues from the pool, and provisions each with a different priority. Each required priority queue ME is connected to the GEM port network CTP associated with that priority. Each required priority queue ME is also connected to the associated T-CONT ME. Any unused queues are left unconnected. + +##### **Weighted scheduling** + +If the service requires weighted scheduling between queues, the OLT selects a T-CONT ME and sets its policy attribute to WRR. The OLT also selects the required number of priority queues from the pool, and provisions the weight of each required priority queue. Each required priority queue is connected to the GEM port network CTP associated with that weight. Each priority queue ME is also connected to the associated T-CONT ME. Any unused queues are left unconnected. + +#### **II.3.4 ONU architectural considerations** + +Depending on the trade-off between the complexity and the number of supported features, the ONU can have various traffic management options. Examples of traffic management implementation in the ONU are described in this clause. This clause also indicates how the MIB defined in clause 9 is used for each implementation. + +It should be pointed out that the ONU traffic management is not limited to these examples. ONU traffic management is likely a place where every vendor searches for a proprietary feature to give it a competitive advantage. However, every proprietary feature requires some kind of management that affects the OMCI. In fact, it is difficult for the specification given in this Recommendation to keep up with technological and feature innovations. It is envisioned that vendor-specific MEs will be needed to manage the traffic management related functions in the ONU. + +##### **II.3.4.1 Priority queue configuration** + +When the focus is on low complexity implementation, the ONU uses the priority-controlled upstream traffic method. This configuration is used when the traffic management option attribute in the ONU-G ME is 0 (priority controlled). In this case, the ONU has no traffic contract or QoS awareness. The ONU is configured by the OLT with a priority for each connection for both directions. + +Theoretically, policing is needed at every multiplexing point, including the ONU. A system with the policing function has to monitor the traffic volume entering the network from all active connections to ensure that the agreed parameters are not violated and to deploy a frame discard or tag policy. In the priority queue implementation, the policing function is moved to the OLT, where it protects the core network. The PON is protected by the PON MAC via the DBA process. The PON MAC manages + +all connections from a T-CONT as a whole. Essentially, the PON MAC isolates T-CONTs from each other. + +As such, CPEs sharing one T-CONT may have to regulate their own connection streams to maintain quality. A CPE sending out more traffic on one connection will do so at the expense of other connections established via the same T-CONT. In single-user ONUs, this may well be appropriate. + +### II.3.4.2 Explicit traffic scheduler configuration + +In slightly more complex implementations, ONUs may implement some level of traffic scheduling within each T-CONT. These are described using priority queues and one or more levels of traffic scheduler MEs. The arrangement of priority queues and traffic schedulers is determined by the ONU architecture, and is by default not controllable by the OLT. Flexible scheduler configuration is one of the options that may be indicated by the ONU2-G ME. + +Figure II.3.4.2-1 exemplifies one possible configuration of traffic schedulers. Two diffserv groups are shown, each with all three classes of traffic. Within each group, two AF queues share weighted access to upstream bandwidth. Traffic in each diffserv group is then strictly prioritized, and finally offered to a weighted scheduler for arbitration across groups. + +![Diagram of hierarchical scheduling example showing traffic flows from priority queues through traffic schedulers to a T-CONT.](f1be2f41ab63bd6132d16190bf5ab76f_img.jpg) + +The diagram illustrates a hierarchical scheduling structure. On the left, there are two groups of priority queues labeled A-1 through A-4 and B-1 through B-4. Each group contains four queues: EF (A-1, B-1), AF (A-2, B-2), AF (A-3, B-3), and BE (A-4, B-4). The AF queues in each group are connected to a common 'W' (Weighted) traffic scheduler. The outputs of these 'W' schedulers are then connected to 'S' (Strict Priority) traffic schedulers. The outputs of the 'S' schedulers are finally connected to a large 'W' (Weighted) traffic scheduler, which in turn connects to a 'T-CONT' (Traffic Container). The label 'Priority queues' is at the top left, and 'Traffic schedulers' is at the bottom left. The diagram is labeled G.988(17)\_FII.3.4.2-1. + +Diagram of hierarchical scheduling example showing traffic flows from priority queues through traffic schedulers to a T-CONT. + +Figure II.3.4.2-1 – Hierarchical scheduling example + +### II.3.4.3 Traffic descriptor configuration + +An alternative method of controlling traffic in ONUs is to provide traffic descriptors to the ONU, and leave the details of honouring and enforcing these contracts to the ONU implementation. This is controlled using traffic descriptor MEs. This method makes the theoretical assumption that a work-conserving scheduling methodology is used. In this configuration, traffic is shaped to conform to PIR and PBS in the traffic descriptor ME. This configuration is used when the traffic management option attribute in the ONU-G ME is 1 (rate controlled). + +### II.3.4.4 Priority and rate controlled configuration + +Another method of controlling traffic in ONUs is to provide not only priority control with traffic scheduling, but also traffic descriptors. This is controlled using traffic descriptor, priority queue and traffic scheduler MEs. This method makes the theoretical assumption that a work-conserving scheduling methodology is used. In this configuration, traffic is policed to conform to PIR and PBS, and may be marked green or yellow according to CIR/CBS/PIR/PBS in the traffic descriptor ME. This configuration is used when the traffic management option attribute in the ONU-G ME is 2 (priority and rate controlled). + +[ITU-T G.987.1] and newer PON specifications require that a multi-UNI ONU be able to serve some UNIs with strict priority and others with rate-based control scheduling. + +#### **II.3.4.5 Flexible assignment** + +By default, priority queues and traffic schedulers are assigned to T-CONTs by the ONU architecture in a fixed configuration, which may not be altered. It is also possible that the ONU implements its QoS components in such a way that they may be flexibly reassigned (Note). ONU flexibility is signalled to the OLT by means of the QoS configuration flexibility bit map attribute of the ONU2-G ME. + +NOTE – Given the slot-port model of ONU equipment, which appears among other places in the ME identifiers of T-CONT, PPTPs, the traffic scheduler and the related port attribute of the priority queue ME, it is not anticipated that implementation flexibility would extend across slots. Accordingly, the OMCI restricts flexibility to be only within a slot, and does not permit flexible assignment across slots. + +### **II.4 Voice services** + +Provisioning of native voice services on an ONU is accomplished through the use of a common set of MEs along with the MEs specific to a particular VoIP signalling protocol. These MEs are grouped as follows. + +- Common VoIP MEs + - IP host config data + - TCP/UDP config data + - VoIP config data + - VoIP voice CTP + - VoIP media profile + - RTP profile data + - Voice service profile + - PPTP POTS UNI +- SIP specific MEs + - SIP user data + - SIP agent data + - Network dial plan table + - VoIP feature access codes + - VoIP app service profile +- ITU-T H.248 specific MEs + - MGC config data. + +The OMCI VoIP MIB allows for one or multiple subscribers per SIP UA. It is also possible to provision one or multiple UAs per IP address. The extended VLAN tagging operation configuration data ME is used to provision layer 2 tag operations for a MAC bridge port config data ME. If multiple UAs using the same IP address are provisioned, all such UAs must share the same VLAN because there is a one-to-one relationship between a MAC bridge port config ME and an IP host config data ME. + +#### **II.4.1 VoIP capability discovery** + +The OLT discovers support of VoIP capabilities by interrogating the ONU's MIB. Support of VoIP in general is indicated by the existence of a VoIP config data ME. Further interrogation of attributes contained in the VoIP config data ME will lead to the discovery of the specific signalling protocols + +and provisioning methods supported by the ONU. The number of voice ports available on an ONU is indicated by the number of PPTP POTS UNI MEs that exist. + +## II.4.2 VoIP common provisioning + +The following considerations pertain to provisioning the common VoIP MEs. + +- IP host config data – The ONU creates one IP host config data ME for each IP stack instance. A single IP address is supported with each instance. The IP host config data ME contains a group of IP parameter attributes (IP address, mask, etc.) that are set by the OLT if these parameters are statically provisioned. The parameters may also be obtained dynamically via DHCP. + +The IP host config data ME contains a read-only group of current IP parameter attributes, which display the IP parameters that are actually used by the IP stack. + +The IP options attribute is used to control the behaviour of the IP stack and IP parameter provisioning. The OLT may set the IP address, mask, gateway, primary or secondary DNS attributes only when the enable DHCP bit is set to disable. If the OLT sets one of these attributes when DHCP is enabled, the ONU accepts and stores the attribute value, but the IP stack does not use those values until the DHCP option is disabled. Likewise, the value is not reflected in the associated current attribute until the DHCP option is disabled. To determine the parameter values actually in use by the IP stack, the OLT should get the current IP parameter attributes, not the writable IP parameter attributes. + +It is considered best practice to disable the IP stack prior to modifying the IP parameters with the OMCI. In this manner, the IP stack will have a complete coherent set of IP parameters when it is re-enabled. + +- TCP/UDP config data – The OLT creates a TCP/UDP config data ME for each TCP or UDP port associated with an IP host config data ME. The OLT may choose to use the port number as the ME ID, but the OLT must ensure that overlapping TCP and UDP port number assignments create no naming conflict. The IP host pointer attribute must be set to point to the IP host config data ME that is associated with this TCP/UDP port. The TOS/diffserv field attribute is used in conjunction with an extended VLAN tagging operation configuration data ME to mark IP frames with the desired VID and P bits. The extended VLAN tagging operation configuration data ME is associated with the MAC bridge port config data ME that points to the IP host config data ME. Since the extended VLAN tagging operation configuration data ME only supports mapping DSCP to P bits, only a single VID can be used for VoIP frames. This means that signalling frames and bearer frames must share a VLAN, although they can have different P bits. +- VoIP config data – The VoIP config data ME is automatically created by the ONU. The OLT reads the available signalling protocols attribute to determine the signalling protocols supported by the ONU. The OLT performs a set on the signalling protocol used attribute to select one of the available signalling protocols. The available VoIP configuration methods attribute is read by the OLT to determine the provisioning methods that are supported by the ONU. The OLT performs a set on the VoIP configuration method used attribute to select one of the available configuration methods. If [BBF TR-069]/[BBF TR-369] or IETF sipping are selected, the OLT need not perform any further actions to provision voice services. If the configuration file retrieval method is selected, the OLT must set the VoIP configuration address pointer to point to a network address ME that provides a retrieval address for the configuration file. Actions required when a proprietary provisioning method is selected are beyond the scope of this Recommendation. +- VoIP voice CTP – The OLT creates the VoIP voice CTP as the last step in basic voice services provisioning. The VoIP voice CTP uses three pointer attributes to tie a POTS port (PPTP POTS UNI) to a signalling protocol (SIP user data ME or MGC config data ME) and + +bearer channel (VoIP media profile ME). In addition, the OLT may set the signalling code attribute to select the POTS line type. + +- VoIP media profile – The OLT creates the VoIP media profile ME to provision the parameters used for voice encoding. The voice service profile pointer and RTP profile pointer attributes must point to the MEs associated with this set of encoding parameters. +- RTP profile data – The OLT creates the RTP profile data ME to provision parameters defining the RTP streams used to carry encoded voice. Since RTP ports are assigned dynamically, no TCP/UDP port config data ME is associated with the RTP streams. The MAC bridge port config data ME associated with the IP host config data used by the signalling stack is the L2-L3 IW point for RTP streams. Any L2 marking of RTP frames should be provisioned using the extended VLAN tagging operation configuration data ME associated with the MAC bridge port config data ME. The DSCP mark attribute of the RTP profile data ME is used in conjunction with the tagging ME to arrive at unique tags for RTP frames. The DTMF events attribute is only meaningful if the OOB DTMF attribute of the VoIP media profile ME is enabled. +- Voice service profile – This ME is created by the OLT to define parameters associated with the carrying of voice over a packet network. It includes the capability to define tone and ringing patterns of considerable complexity, including the playback of files such as verbal announcements and ring tones. +- PPTP POTS UNI – This ME is automatically created by the ONU for each POTS port. The IW TP pointer attribute is not meaningful in the context of VoIP and is left as a null pointer. + +#### II.4.3 SIP provisioning + +The following considerations apply to provisioning the SIP MEs: + +- SIP user data – The SIP user data ME is created by the OLT to define the parameters associated with a single subscriber. The username/password attribute points to the data used for subscriber authentication, not SIP agent authentication. The release timer attribute has a default value of 10 s. If the release timer attribute is set to zero, the ONU uses its internal default release timer value. This may or may not be the same as the attribute default of 10 s and is not discoverable by the OLT. +- SIP agent config data – The SIP agent config data ME defines parameters associated with a SIP UA. The proxy server address pointer attribute points to a large string ME; no authentication is associated with this address. Proxy server authentication is performed through the use of the SIP registrar attribute that may or may not point to the same address as the proxy server address pointer attribute. The TCP/UDP pointer attribute points to the TCP/UDP config data ME that defines the port to be used by the SIP signalling protocol. +- Network dial plan table – The network dial plan table ME is optionally created by the OLT if a dial plan other than the ONU's default is required. When it receives the create command, the ONU returns an unknown ME result-reason code if it does not support dial plans beyond the default. There is no mechanism for the OLT to discover the default dial plan of an ONU. +- VoIP feature access codes – The VoIP feature access codes ME is optionally created by the OLT if feature access codes other than the ONU's default are required. When it receives the create command, the ONU returns an unknown ME result-reason code if it does not support VoIP feature access codes beyond the default. There is no mechanism for the OLT to discover the default feature access codes of an ONU. +- VoIP application service profile – The VoIP application service profile ME is optionally created by the OLT if provisioning of VoIP features is required. When it receives the create command, the ONU returns an unknown ME result-reason code if it does not support VoIP feature provisioning. There is no mechanism for the OLT to discover the default VoIP features of an ONU. + +#### **II.4.4 ITU-T H.248 provisioning** + +The following considerations apply to provisioning the ITU-T H.248 MEs: + +- MGC config data – The MGC config data ME is created by the OLT to provision the parameters associated with an ITU-T H.248 media gateway. The primary MGC and secondary MGC attributes point to network address MEs that contain IP addresses and may contain port numbers for the MGC. These port numbers are not necessarily the same as the media gateway port number defined in the TCP/UDP port config data ME. The default port used for the MGC depends on the value contained in the message format attribute. + +#### **II.4.5 Message flows** + +##### **II.4.5.1 SIP provisioning flow** + +Figure II.4.5.1-1 depicts the provisioning flow for a basic SIP service. To assist in overall clarity, the provisioning of optional MEs is not included, nor is the provisioning of the various ME pointers. + +![Sequence diagram showing SIP provisioning flow between OLT and ONU. The OLT sends various configuration messages to the ONU, including VoIP config data, IP host config, MAC bridge port config, TCP/UDP config, SIP proxy server address, authentication security, network address, SIP agent config data, SIP user part AOR, SIP user data, RTP profile data, voice service profile, VoIP media profile, and VoIP voice CTP. The ONU responds with VoIP config data. Callouts explain that the OLT verifies OMCI and SIP support, and that the ONU is now provisioned for DHCP.](e41e58044b89601b2e949f518af843eb_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT verifies that the ONU supports the OMCI and SIP based on returned attribute values. This is typically performed as a part of ONU discovery but is shown here as a separate action for completeness. + OLT->>ONU: Get (VoIP config data [avail VoIP config, avail signalling]) + ONU-->>OLT: Get response (VoIP config data) + OLT->>ONU: Set (IP host config [IP options = DHCP]) + Note right of ONU: The ONU is now provisioned to use DHCP for obtaining IP attributes. The ONU may immediately begin contacting a DHCP server. + OLT->>ONU: Create (MAC bridge port config data) + OLT->>ONU: Create (TCP/UDP config data) + OLT->>ONU: Set (VoIP config data [VoIP config method = OMCI, signalling protocol used = SIP]) + OLT->>ONU: Create (large string [SIP proxy server address]) + OLT->>ONU: Create (authentication security []) + OLT->>ONU: Create (network address []) + OLT->>ONU: Create (SIP agent config data []) + OLT->>ONU: Set (SIP agent config data [TCP/UDP pointer = TCP/UDP config data]) + OLT->>ONU: Create (large string [SIP user part AOR]) + OLT->>ONU: Create (SIP user data) + OLT->>ONU: Create (RTP profile data) + OLT->>ONU: Create (voice service profile) + OLT->>ONU: Create (VoIP media profile) + Note right of OLT: If the OLT provisions a codec in the VoIP media profile that is not supported by the ONU, the ONU returns a parameter error. + OLT->>ONU: Create (VoIP voice CTP) + Note right of OLT: Basic SIP provisioning is now complete. Specific features may be provisioned using attributes in the VoIP application service profile ME + +``` + +Sequence diagram showing SIP provisioning flow between OLT and ONU. The OLT sends various configuration messages to the ONU, including VoIP config data, IP host config, MAC bridge port config, TCP/UDP config, SIP proxy server address, authentication security, network address, SIP agent config data, SIP user part AOR, SIP user data, RTP profile data, voice service profile, VoIP media profile, and VoIP voice CTP. The ONU responds with VoIP config data. Callouts explain that the OLT verifies OMCI and SIP support, and that the ONU is now provisioned for DHCP. + +G.988(12)\_FII.4.5.1-1 + +**Figure II.4.5.1-1 – SIP provisioning flow** + +## II.4.5.2 ITU-T H.248 message flow + +Figure II.4.5.2-1 depicts the provisioning flow for ITU-T H.248 service. To assist in overall clarity, the explicit provisioning of the various ME pointers is not included. + +![Sequence diagram showing the ITU-T H.248 provisioning flow between an OLT and an ONU. The process involves configuration data exchange, IP host configuration, and creation of various media gateway and service profiles.](d70073925b61e50ee2380a2a8fc6197c_img.jpg) + +``` + +sequenceDiagram + participant OLT + participant ONU + Note left of OLT: The OLT verifies that the ONU supports the OMCI and ITU-T H.248 based on returned attribute values. This is typically performed as a part of ONU discovery but is shown here as a separate action for completeness. + OLT->>ONU: Get (VoIP config data [avail VoIP config, avail signalling]) + ONU-->>OLT: Get response (VoIP config data) + Note right of ONU: The ONU is now provisioned to use DHCP to obtain IP attributes. The ONU may immediately begin contacting a DHCP server. + OLT->>ONU: Set (IP host config [IP options = DHCP]) + OLT->>ONU: Create (MAC bridge port config data) + OLT->>ONU: Create (TCP/UDP config data) + OLT->>ONU: Set (VoIP config data [VoIP config method = OMCI, signalling protocol used = ITU-T H.248]) + OLT->>ONU: Create (large string [Media gateway controller address]) + OLT->>ONU: Create (authentication security []) + Note right of ONU: Once for primary, once for secondary. + OLT->>ONU: Create (network address []) + OLT->>ONU: Create (MGC config data []) + OLT->>ONU: Create (RTP profile data) + OLT->>ONU: Create (voice service profile) + OLT->>ONU: Create (VoIP media profile) + Note left of OLT: If the OLT provisions a codec in the VoIP media profile that is not supported by the ONU, the ONU returns a parameter error. + OLT->>ONU: Create (VoIP voice CTP) + Note left of OLT: ITU-T H.248 provisioning is now complete. + +``` + +G.988(12)\_FII.4.5.2-1 + +Sequence diagram showing the ITU-T H.248 provisioning flow between an OLT and an ONU. The process involves configuration data exchange, IP host configuration, and creation of various media gateway and service profiles. + +**Figure II.4.5.2-1 – ITU-T H.248 provisioning flow** + +## II.4.6 Voice service in a dual-managed ONU + +In addition to supporting full voice service provisioning, the OMCI also supports ONUs that use a method other than the OMCI to manage voice services. This clause describes the techniques that are used for supporting a non-OMCI managed voice service. + +### II.4.6.1 Common provisioning + +The following considerations apply to provisioning the common VoIP MEs for a non-OMCI managed voice service. + +- IP host config data – The ONU creates the IP host config data ME for each IP stack instance. Attributes in this ME provide the IP parameters used for the non-OMCI management interface. There is no direct relation between this ME and VoIP provisioning. + +- TCP/UDP config data – The OLT creates a TCP/UDP config data ME for the port used by the non-OMCI management interface. There is no direct relation between this ME and VoIP provisioning. +- VoIP config data – The VoIP config data ME is automatically created by the ONU when it supports a native voice service. The OLT reads the available VoIP configuration methods attribute to discover the voice service management methods supported by this ONU. The OLT performs a set on the VoIP configuration method used attribute to select the non-OMCI method to be used by the ONU. The OLT may optionally set the VoIP configuration address pointer attribute to a network location from which the ONU will receive its voice provisioning parameters. The OLT also optionally sets the retrieve profile attribute to indicate to the ONU that it must retrieve the provisioning parameters for the voice service. The ONU uses the VoIP configuration state attribute to indicate the state of voice service provisioning. The ONU uses the profile version attribute to indicate the version of the voice service parameter set that it is currently using. +- VoIP voice CTP – Not used. +- VoIP media profile – Not used. +- RTP profile data – Not used. +- Voice service profile – Not used. +- PPTP POTS UNI – Used in the same manner as described in clause II.4.2. + +#### II.4.6.2 SIP provisioning + +When an ONU supports non-OMCI provisioning of SIP, it automatically creates a SIP config portal ME. This ME contains a single table attribute: the configuration text table. The OLT reads this table to obtain a textual representation of the SIP configuration in use on the ONU. Whenever the text in this table changes, the ONU issues an AVC to the OLT. The format of the text contained within the table is not defined but should be human-readable. + +#### II.4.6.3 ITU-T H.248 provisioning + +When an ONU supports non-OMCI provisioning of ITU-T H.248, it automatically creates an ITU-T H.248 config portal ME. This ME contains a single table attribute: the configuration text table. The OLT reads this table to obtain a textual representation of the ITU-T H.248 configuration in use on the ONU. Whenever the text in this table changes, the ONU issues an AVC to the OLT. The format of the text contained within the table is not defined but should be human-readable. + +### II.5 Extended layer 2 data service model + +The L2-OCM is the minimum that should be supported by all G-PON systems. It is based on the 1:MP model of ITU-T G.988 Figure 8.2.2-7. This model combines MAC bridging and IEEE 802.1p mapping functionality for a single UNI. ITU-T G.988 Figure II.1.2.1-1 illustrates L2-OCM applied to a single UNI ONU. + +Figure II.5-1 shows the system level diagram of a LAG-based channel bonding example. It extends the single UNI ONU model in ITU-T G.988 Appendix II with LAG-based channel bonding. This ONU contains a single UNI and two ANIs. It supports both unicast and multicast transmission. It also supports bonded and unbonded upstream transmission. The two ANIs are connected to two OLT CTs at the OLT side. The OLT would aggregate them into a single SNI by using a LAG bridge. In most cases the two OLT CTs are in the same PON. It is possible the two OLT CTs belong to two different PON systems (e.g., TWDM-PON1 and TWDM-PON2), or even two different PON technologies (e.g., XGS-PON and TWDM-PON). + +![Figure II.5-1: LAG-based channel bonding diagram. The diagram shows a network architecture starting with an SNI connected to a LAG bridge. This bridge is connected to two OLTs (OLT-1 and OLT-2), which are in turn connected to an ODN (Optical Distribution Network). The ODN connects to two ANI interfaces (ANI 1 and ANI 2) within an ONU. ANI 1 connects to ANI-G-1, and ANI 2 connects to ANI-G-2. Both ANI-G-1 and ANI-G-2 connect to a second LAG bridge. This second LAG bridge is connected to a PPTP, which is finally connected to a UNI. A label 'G.988(17)-Amd.1(18)_FII.5-1' is present at the bottom right of the diagram.](e791584696ddaa89eecf172a72ae05e9_img.jpg) + +Figure II.5-1: LAG-based channel bonding diagram. The diagram shows a network architecture starting with an SNI connected to a LAG bridge. This bridge is connected to two OLTs (OLT-1 and OLT-2), which are in turn connected to an ODN (Optical Distribution Network). The ODN connects to two ANI interfaces (ANI 1 and ANI 2) within an ONU. ANI 1 connects to ANI-G-1, and ANI 2 connects to ANI-G-2. Both ANI-G-1 and ANI-G-2 connect to a second LAG bridge. This second LAG bridge is connected to a PPTP, which is finally connected to a UNI. A label 'G.988(17)-Amd.1(18)\_FII.5-1' is present at the bottom right of the diagram. + +**Figure II.5-1 – LAG-based channel bonding** + +Figure II.5-2 illustrates the OMCI model of the ONU in Figure II.5-1. ANI-G interface 1 and ANI-G interface 2 are bonded via the LASP ME in the upstream. In ANI-G interface 1, the bonded traffic is configured by the MAC bridge port configuration data 1 ME, and managed by priority queue 1-1 (PQ1-1) and priority queue 1-2 (PQ1-2). The unbonded traffic is configured by the MAC bridge port configuration data 2 ME, and the priority queues are PQ1-3 and PQ1-4. The mixed bonded and unbonded traffic management in ANI-G interface 1 is shown in Figure II.5-2 with a box of blue dashed outline. + +In ANI-G interface 2, the bonded traffic is configured by the MAC bridge port configuration data 3 ME, and managed by priority queue 2-1 (PQ2-1) and priority queue 2-2 (PQ2-2). Its unbonded traffic is configured by the MAC bridge port configuration data 4 ME, and the priority queues are PQ2-3 and PQ2-4. The mixed bonded and unbonded traffic management in ANI-G interface 2 is shown in Figure II.5-2 with a box of red dashed outline. + +Bonded traffic in ANI-G interface 1 and ANI-G interface 2 belongs to the same LAG. This LAG is represented by the LASP ME in Figure II.5-2 and both the MAC bridge port configuration data 1 ME and the MAC bridge port configuration data 3 ME contain a pointer to the LASP ME. + +The QoS attributes on all bonded MAC bridge ports in a LAG should be similarly configured. In the example of Figure II.5-2, the VLAN tagging filter ME, the 802.1p mapper service profile ME, the GEM interworking TP ME, the GEM port network CTP ME, the traffic fdescriptor ME, and the priority queue ME should be similarly configured for the bonded MAC bridge ports (i.e., Port 1 and Port 3 in Figure II.5-2). This ensures equal treatment on all bonded MAC bridge ports in the same LAG. + +The downstream multicast traffic is managed via two MAC bridge port configurations data MEs in the yellow dashed outline box. The upper one is represented by an instance of the GEM interworking termination point ME. It carries the incidental downstream broadcast traffic. The lower one is represented by an instance of the multicast GEM interworking termination point ME. It carries the general multicast traffic. + +![A complex block diagram showing the internal architecture of an Optical Network Unit (ONU) for LAG-based channel bonding. The diagram illustrates the flow of data from various sources (Circuit pack, Cardholder, ONT-G, UNI-G, PTP Ethernet UNI) through internal processing blocks (VLAN tagging filter, MAC bridge port config data, 802.1p mapper service profile, GEM interworking TP, GEM port network CTP) to multiple output queues (T-CONT, Priority queue) for transmission. The diagram is divided into three main functional sections: ONT data processing (top), PTP Ethernet UNI processing (middle), and UNI-G processing (bottom). Each section shows how traffic is classified, prioritized, and mapped to specific GEM ports and network CTPs. Annotations include 'Traffic descriptor (Downstream)' and 'Traffic descriptor (upstream)' for each GEM port network CTP. A note at the bottom right indicates '*1 downstream direction only' and the document reference 'G.988(17)-Amd.5(22)_FI1.5-2'.](2e41e2ef597e9e674be64efd745dca8e_img.jpg) + +\*1 downstream direction only +G.988(17)-Amd.5(22)\_FI1.5-2 + +A complex block diagram showing the internal architecture of an Optical Network Unit (ONU) for LAG-based channel bonding. The diagram illustrates the flow of data from various sources (Circuit pack, Cardholder, ONT-G, UNI-G, PTP Ethernet UNI) through internal processing blocks (VLAN tagging filter, MAC bridge port config data, 802.1p mapper service profile, GEM interworking TP, GEM port network CTP) to multiple output queues (T-CONT, Priority queue) for transmission. The diagram is divided into three main functional sections: ONT data processing (top), PTP Ethernet UNI processing (middle), and UNI-G processing (bottom). Each section shows how traffic is classified, prioritized, and mapped to specific GEM ports and network CTPs. Annotations include 'Traffic descriptor (Downstream)' and 'Traffic descriptor (upstream)' for each GEM port network CTP. A note at the bottom right indicates '\*1 downstream direction only' and the document reference 'G.988(17)-Amd.5(22)\_FI1.5-2'. + +**Figure II.5-2 – Supporting LAG-based channel bonding in an ONU (based on ITU-T G.988 Figure II.1.2.1-1 – Single UNI, VLANs with common priorities)** + +## **Appendix III** + +*This appendix is intentionally left blank* + +## Bibliography + +- [b-ATIS-0300231] ATIS-0300231:2013, *Layer 1 in-service transmission performance monitoring*. +- [b-ATIS-0600403] ATIS-0600403:1999 (R2012), *Network and customer installation interfaces – DS1 electrical interfaces*. +- [b-ATIS-0600413] ATIS-0600413.2009, *Network to customer installation interfaces – Asymmetric digital subscriber line (ADSL) metallic interface*. +- [b-BBF TR-101] Digital Subscriber Line Forum Technical Report TR-101 (2006), [Migration to Ethernet based DSL aggregation](https://www.broadband-forum.org/technical/download/TR-101.pdf). Available [viewed 2018-01-05] at +- [b-BBF TR-156] Broadband Forum Technical Report TR-156 (2012), [Using GPON access in the context of TR-101](http://www.broadband-forum.org/technical/download/TR-156_issue-3.pdf). Available [viewed 2018-01-05] at <[http://www.broadband-forum.org/technical/download/TR-156\\_issue-3.pdf](http://www.broadband-forum.org/technical/download/TR-156_issue-3.pdf)> +- [b-IANA] [Internet Assigned Numbers Authority](http://www.iana.org). Available [viewed 2018-01-03] at [www.iana.org](http://www.iana.org) +- [b-IETF RFC 2460] IETF RFC 2460 (1998), *Internet protocol, version 6 (IPv6): Specification*. +- [b-IETF RFC 2463] IETF RFC 2463 (1998), *Internet control message protocol (ICMPv6) for the Internet protocol version 6 (IPv6): Specification*. +- [b-IETF RFC 2475] IETF RFC 2475 (1998), *An architecture for differentiated services*. +- [b-IETF RFC 2516] IETF RFC 2516 (1999), *A method for transmitting PPP over Ethernet (PPPoE)*. +- [b-IETF RFC 2543] IETF RFC 2543 (1999), *SIP: Session Initiation Protocol*. +- [b-IETF RFC 2571] IETF RFC 2571 (1999), *An architecture for describing SNMP management frameworks*. +- [b-IETF RFC 2698] IETF RFC 2698 (1999), *A two rate three color marker*. +- [b-IETF RFC 2710] IETF RFC 2710 (1999), *Multicast listener discovery (MLD) for IPv6*. +- [b-IETF RFC 3232] IETF RFC 3232 (2002), *Assigned numbers: RFC 1700 is replaced by an on-line database*. +- [b-IETF RFC 3247] IETF RFC 3247 (2002), *Supplemental information for the new definition of the EF PHB (expedited forwarding per-hop behavior)*. +- [b-IETF RFC 3264] IETF RFC 3264 (2002), *An offer/answer model with the session description protocol (SDP)*. +- [b-IETF RFC 3315] IETF RFC 3315 (2003), *Dynamic host configuration protocol for IPv6 (DHCPv6)*. +- [b-IETF RFC 3339] IETF RFC 3339 (2002), *Date and Time on the Internet: Timestamps*. +- [b-IETF RFC 3418] IETF RFC 3418 (2002), *Management information base (MIB) for the simple network management protocol (SNMP)*. +- [b-IETF RFC 3621] IETF RFC 3621 (2003), *Power Ethernet MIB*. +- [b-IETF RFC 3926] IETF RFC 3926 (2004), *FLUTE – File delivery over unidirectional transport*. + +- [b-IETF RFC 4115] IETF RFC 4115 (2005), *A differentiated service two-rate, three-color marker with efficient handling of in-profile traffic.* +- [b-IETF RFC 4291] IETF RFC 4291 (2006), *IP version 6 addressing architecture.* +- [b-IETF RFC 4541] IETF RFC 4541 (2006), *Considerations for Internet group management protocol (IGMP) and multicast listener discovery (MLD) snooping switches.* +- [b-IETF RFC 4861] IETF RFC 4861 (2007), *Neighbor discovery for IP version 6 (IPv6).* +- [b-IETF RFC 4862] IETF RFC 4862 (2007), *IPv6 stateless address autoconfiguration.* +- [b-IETF RFC 5462] IETF RFC 5462 (2009), *Multiprotocol label switching (MPLS) label stack entry: "EXP" field renamed to "Traffic Class" field.* +- [b-IETF RFC 5942] IETF RFC 5942 (2010), *IPv6 subnet model: The relationship between links and subnet prefixes.* +- [b-IETF RFC 6106] IETF RFC 6106 (2010), *IPv6 router advertisement options for DNS configuration.* +- [b-MEF 10.2] Metro Ethernet Forum Technical Specification MEF10.2 (2009), [Ethernet services attributes phase 2](https://mef.net/PDF_Documents/technical-specifications/MEF10.2.pdf). Available [viewed 2018-01-05] at: [https://mef.net/PDF\\_Documents/technical-specifications/MEF10.2.pdf](https://mef.net/PDF_Documents/technical-specifications/MEF10.2.pdf) +- [b-PKT-SP-NCS] CableLabs, PKT-SP-NCS1.5-I04-120412 (2012), *PacketCable network-based call signaling protocol specification.* +- [b-Floyd] Floyd, S., Jacobson, V. (1993). Random early detection gateways for congestion avoidance. *IEEE/ACM Transactions on Networking*, 1(4), pp. 397-413. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation 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with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in blue. + +ITU logo + +International +Telecommunication +Union + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9905 + +# Centralized metric-based source routing + +# Summary + +Recommendation ITU-T G.9905 specifies centralized metric based source routing (CMSR), a proactive, layer 2 multi-hop routing protocol. CMSR is a proactive routing protocol which can find and maintain reliable routes considering the link quality of both directions. The routing control packet overhead of CMSR is quite low compared to existing proactive routing protocols such as optimized link state routing (OLSR), so that it can be applied for large-scale networks even on narrow band power line communication (PLC) networks. + +# History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------------| +| 1.0 | ITU-T G.9905 | 2013-08-29 | 15 | 11.1002/1000/12007-en | + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +# FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +# INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2014 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +# Table of Contents + +###### Page + +| | | | +|---------|-------------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 1 | +| 3.1 | Terms defined elsewhere ..... | 1 | +| 3.2 | Terms defined in this Recommendation..... | 1 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Protocol overview ..... | 2 | +| 5.1 | Outline of operation..... | 2 | +| 5.2 | Table overview ..... | 5 | +| 5.3 | Signalling overview..... | 6 | +| 5.4 | Protocol parameters ..... | 7 | +| 6 | Table and information base ..... | 7 | +| 6.1 | Neighbour table ..... | 7 | +| 6.2 | Route table..... | 8 | +| 7 | Message format..... | 8 | +| 7.1 | CMSR source route header..... | 9 | +| 7.2 | CMSR message ..... | 9 | +| 8 | Procedure ..... | 14 | +| 8.1 | Hello message exchange..... | 14 | +| 8.2 | Topology report message transmission ..... | 18 | +| 8.3 | Route Error message transmission ..... | 19 | +| 8.4 | Link break determination ..... | 19 | +| 8.5 | Route break determination ..... | 19 | +| 9 | Packet transmission ..... | 19 | +| 9.1 | Unicast packet ..... | 19 | +| 9.2 | Broadcast/multicast packet..... | 20 | +| 10 | Configuration parameters ..... | 20 | +| Annex A | – Routing procedure for ITU-T G.9903 ..... | 21 | +| A.1 | Defining parameter..... | 21 | +| A.2 | Mesh routing..... | 21 | +| A.3 | Transmission of IPv6 packet triggered by ADPD-DATA primitive..... | 23 | +| A.4 | Packet transmission and reception triggered by non-default routing entity ... | 24 | +| A.5 | Interface between the ITU-T G.9903 adaptation layer and ITU-T G.9905.... | 24 | + + + +## Recommendation ITU-T G.9905 + +# Centralized metric-based source routing + +# 1 Scope + +This Recommendation specifies centralized metric based source routing (CMSR), a proactive, layer 2 multi-hop routing protocol. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +[ITU-T G.9903] Recommendation ITU-T G.9903 (2014), *Narrowband orthogonal frequency division multiplexing power line communication transceivers for G3-PLC networks*. + +[IETF RFC 4944] IETF RFC 4944 (2007), *Transmission of IPv6 Packets over IEEE 802.15.4 Networks*. + +[IETF RFC 6282] IETF RFC 6282 (2011), *Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 1WAY link:** A link between neighbour nodes for which only the incoming link cost is available. + +**3.2.2 2WAY link:** A link between neighbour nodes for which both incoming and outgoing link costs are available. + +**3.2.3 Hello message:** A message transmitted by each node in order both to notify its existence and to exchange link cost and route information with neighbour nodes. + +**3.2.4 LC incoming:** The cost of a one-way link from a neighbour node. + +**3.2.5 LC outgoing:** The cost of a one-way link toward a neighbour node. + +**3.2.6 link:** A link between two nodes exists if either can receive control messages from the other, according to this specification. + +**3.2.7 link cost (LC):** The cost of a link between a pair of nodes, calculated from bidirectional link quality. The LC value used is the greater of "LC incoming" and "LC outgoing". + +**3.2.8 LOST link:** A broken link where communication is no longer possible. + +**3.2.9 node:** Communication equipment, including the personal area network (PAN) coordinator, which communicates using the CMSR protocol according to this specification. + +**3.2.10 provisional route cost:** The provisional route quality between a node and the coordinator, equal to the sum of the route cost from a neighbour node to the coordinator and the LC incoming from the neighbour node. + +**3.2.11 route cost:** The total route quality between a node and the coordinator, equal to the sum of all link costs in the route from the node to the coordinator. + +**3.2.12 topology report message:** A message transmitted to the coordinator (using unicast) that contains route and neighbour node information. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +CMSR Centralized Metric based Source Routing + +LC Link Cost + +MAC Media Access Control + +NSDU Network Service Data Unit + +PAN Personal Area Network + +PLC Power Line Communication + +# 5 Protocol overview + +Multi-hop routing protocols are a key feature of communication for advanced metering applications over power line communications (PLCs). For a large-scale PLC network, e.g., PLC deployment in a large-scale apartment building, a robust and low overhead routing protocol is required in order to achieve reliable metering. + +This Recommendation addresses the following main objectives: + +- Perform mesh-under proactive routing on 6LoWPAN in IPv6 networks, and communicate using 16-bit short addresses used by 6LoWPAN. +- Discover a bidirectional route between a node and a coordinator, taking bidirectional link quality into account. +- Establish and maintain multiple reliable routes in case route break occurs. +- Generate control packets which increase as only $O(N)$ for route discovery and maintenance (with $N$ being the number of nodes present in the network). +- Deliver data packets with source routing and/or hop-by-hop routing. + +## 5.1 Outline of operation + +CMSR performs mesh-under routing on 6LoWPAN in IPv6 networks, and communicates using 16-bit short addresses used by 6LoWPAN. In order to perform neighbour node detection and route discovery, a Hello message is used for exchanging route and link quality information between nodes, whereas a topology report message is used to notify the coordinator. The coordinator and nodes maintain neighbour tables for storing information on neighbour nodes, and route tables for storing route information. Each node determines an optimal route based on the link quality and the number of hops to the coordinator. + +### 5.1.1 Route discovery + +Route discovery is carried out with the three steps shown in Figure 5-1. + +![Flowchart of route discovery steps](562f471e8153729557e6a4ee6343c32c_img.jpg) + +``` +graph TD; S1[Step 1: Hello message exchange and neighbour table update] --> S2[Step 2: Determine or update route]; S2 --> S3[Step 3: Topology report message transmission]; +``` + +The diagram illustrates the three steps of route discovery in a vertical flowchart. Each step is represented by a blue rectangular box with white text. To the right of each box is a description of the step's purpose. Step 1: 'Hello message exchange and neighbour table update' - 'Establish 2WAY link(s) with the neighbour node(s) that has a route to the coordinator and lower provisional route cost.' Step 2: 'Determine or update route' - 'Determine or update the route to the coordinator based on route cost.' Step 3: 'Topology report message transmission' - 'Inform the coordinator of the route information.' Downward-pointing arrows connect the boxes. In the bottom right corner of the diagram area, the text 'G.9905(13)\_F5-1' is present. + +Flowchart of route discovery steps + +Figure 5-1 – Overview of route discovery steps + +#### Step 1: Hello message exchange and neighbour table update + +Each node periodically transmits the Hello message as a 1-hop broadcast message with the interval of HELLO\_INTERVAL (or HELLO\_INTERVAL\_FAST as mentioned in clause 8.1.1). In order to avoid a permanent collision of Hello messages, each node randomly shifts the transmission timing. The maximum timing shift is defined by HELLO\_JITTER. + +For route discovery, the node establishes a 2WAY link with the node which already has a route to the coordinator. Figure 5-2 shows how the 2WAY link is established. The node that receives the Hello message stores the information included in the Hello message in the neighbour table. When the node receives a Hello message from its neighbour node for the first time, the link between the nodes is considered as a 1WAY link (meaning that the node has measured the LC incoming from that neighbour node but does not know the LC outgoing to that neighbour node). The receiving node calculates the provisional route cost as the sum of the route costs in the received Hello messages and the measured LC incoming. The status, LC incoming and provisional route cost are recorded in the neighbour table (first phase in Figure 5-2). + +The node selects the neighbour nodes based on the provisional route costs, i.e., neighbour nodes with lowest provisional route costs. Up to LINK\_MAX\_PREFERRED neighbour nodes may be selected. The node sends a Hello message with the link request (LINK\_REQ sub-message) to the selected neighbour nodes to obtain the LC outgoing. Upon reception of the LINK\_REQ sub-message, the neighbour nodes record the LC incoming and LC outgoing according to the received message (second phase in Figure 5-2). + +The neighbour nodes transmit LINK REP sub-messages including the LC incoming to the originator of the LINK REQ. The originator node stores the LC incoming in the received LINK REP sub-message as LC outgoing, and sets the link status as "2WAY" (third phase in Figure 5-2). + +Note that the LINK REQ and LINK REP sub-messages are transmitted in the Hello message that is periodically transmitted with the interval of HELLO\_INTERVAL (or HELLO\_INTERVAL\_FAST). + +![Diagram illustrating the establishment of a 2WAY link between Node 1 and Node 2 through three phases, involving HELLO, LINK_REQ, and LINK REP messages, with a Coordinator node.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +The diagram illustrates the establishment of a 2WAY link between Node 1 and Node 2 through three phases, with a Coordinator node also shown. + +**Phase 1:** Node 1 sends a **LINK\_UPPER** message containing a **HELLO** sub-message to Node 2. Node 2 receives this and performs the following actions: + +- Set Node 2 "LC Incoming" entry according to link quality of received HELLO +- Set Node 2 "status" entry to 1WAY + +A dashed box indicates: "If Node 1 has received Hello packets from multiple nodes, Node 1 selects nodes with lower provisional route cost for LINK\_REQ transmission." + +**Phase 2:** Node 1 sends a **LINK\_REQ** message containing a **HELLO** sub-message to Node 2. Node 2 receives this and performs the following actions: + +- Set Node 1 "LC Incoming" entry according to link quality of received HELLO and "LC Outgoing" entry to LC value in LINK\_REQ +- Set Node 1 "status" to 2WAY + +**Phase 3:** Node 2 sends a **LINK REP** message containing a **HELLO** sub-message to Node 1. Node 1 receives this and performs the following actions: + +- Set Node 2 "LC Outgoing" entry according to value in LINK REP +- Set Node 2 "status" to 2WAY + +The diagram is labeled G.9905(13)\_F5-2. + +Diagram illustrating the establishment of a 2WAY link between Node 1 and Node 2 through three phases, involving HELLO, LINK\_REQ, and LINK REP messages, with a Coordinator node. + +**Figure 5-2 – Establishment of 2WAY link using LINK\_REQ/LINK REP sub-messages** + +#### **Step 2: Route determination/update** + +The node may receive LINK REP sub-messages from more than one neighbour node in Step 1. The node calculates the route cost associated with each neighbour node based on the link cost (i.e., greater of LC incoming and LC outgoing) and the route cost information in the LINK REP sub-message from the neighbour node. The node selects the route with the least route cost. Other routes may be selected as candidates for route recovery. The route information, i.e., relay node addresses and each link cost, is stored in the route table. + +If the node already has the route to the coordinator and it finds a better route, the route may be updated. + +#### **Step 3: Topology Report message transmission (route update for the coordinator)** + +The Topology Report message is used to inform the coordinator of the routes used by each node, 2WAY links associated with each node and broken links associated with each node. The node periodically transmits a Topology Report message toward the coordinator. The coordinator updates the route table for each node based on the received Topology Report messages. Note that the coordinator does not transmit the Topology Report message. + +The above steps are repeated and each node updates the route based on the Hello messages and the Topology Report messages periodically transmitted by other nodes. + +### 5.1.2 Fast mode operation + +Fast mode is used to shorten the route discovery time. The node in fast mode transmits the Hello message with an interval of HELLO\_INTERVAL\_FAST. If the node does not currently have a route to the coordinator, the node operates with the fast mode and may request its neighbour nodes to operate in fast mode by setting the fast mode flag in the Hello message. Any node which receives a Hello message with fast mode flag set to "enable" shall operate with fast mode for a certain period. + +### 5.1.3 Route recovery + +CMSR allows a node to maintain alternative routes in case broken links occur. + +For upstream communication, each node has the route to the coordinator and possibly an alternative route. If the node stores an alternative route, it changes the route immediately. + +For downstream communication with source routing, the node reports the failure to the source node (i.e., coordinator), which allows the coordinator to select an alternative route. + +### 5.1.4 Packet delivery + +#### 5.1.4.1 Unicast packet + +The coordinator and the nodes send upper layer packets using the discovered route. + +In upstream communication (from a node to the coordinator), a source node sends packets only to an upstream destination neighbour node. In order to facilitate rapid route recovery, the route to the coordinator is not included in these packets. Each node relays the packet to the uplink in a hop-by-hop manner. + +In downstream communication (from the coordinator to a node), the coordinator shall select one of two methods – source routing or hop-by-hop. In source routing, the coordinator specifies the entire route to the final destination and the CMSR source route header is attached to the packet. This is necessary as, in order to reduce memory resource usage, nodes do not hold route information to other nodes. In hop-by-hop, the coordinator transmits the packet to the next hop, and the relay node forwards the packet based on the route information stored in the route table. These methods can be selected according to system requirements. + +#### 5.1.4.2 Broadcast packet + +Only a limited number of nodes forward a broadcast packet in order to avoid congestion in a large-scale network. Only nodes which are listed in the LINK\_UPPER sub-message of the Hello messages from the different nodes are enabled to forward a broadcast packet. + +## 5.2 Table overview + +The necessary protocol state is recorded in the route table and the neighbour table. Every node has its own tables. + +The route table contains tuples of destination short address, route cost, hop count and short address list of relay nodes to the destination. The node updates the route table when it finds or updates the route based on received Hello messages or when it receives a Topology Report message from a node. + +The neighbour table contains tuples of neighbour node address, node type, link status, link cost incoming, link cost outgoing, link cost of relay link, short address list of relay nodes and the route cost. The node updates the neighbour table according to Hello messages received from neighbour nodes. + +## 5.3 Signalling overview + +This protocol generates and processes the CMSR message and the source route header. The CMSR message includes three types of messages, Hello message, Topology Report message and Route Error message. + +### 5.3.1 Hello message + +The Hello message is used by nodes to notify their existence and status to each other in the route discovery process. The Hello message contains one or more of the following four sub-messages. + +LINK\_UPPER sub-message: Used to notify the route from the node to the coordinator and each link cost within the route. This sub-message contains the list of relay node addresses and the link cost of each link. + +LINK\_REQ sub-message: Used to request a neighbour node to feedback the link cost from the node to the neighbour node. This sub-message also indicates to the neighbour node that the link between the node and the neighbour node is a 1WAY link. This sub-message contains one or more sets of the target node address and its link cost. + +LINK\_REP sub-message: Used to respond to the LINK\_REQ sub-message received from a neighbour node. This sub-message contains one or more sets of the target node and its link cost (i.e., outgoing link cost for the neighbour node). + +LINK\_LOST sub-message: Used to notify the existence of a broken link. This sub-message contains one or multiple sets of the target node and its link cost (must be zero). LINK\_LOST is determined by the lack of reception of a Hello message from a node for a period given by HELLO\_MAX\_COUNT multiplied with HELLO\_INTERVAL. + +For reliable message delivery, more than one transmission of LINK\_REQ, LINK\_REP and LINK\_LOST sub-messages addressed to a certain neighbour node may be conducted. The number of transmissions is given by NOTIFY\_MAX\_COUNT. + +### 5.3.2 Topology Report message + +The Topology Report message contains information on the route to the coordinator and link status with neighbour nodes. Each node generates a Topology Report message based on the route table and the neighbour table, and periodically sends it to the coordinator. A Topology Report message contains one or more of the following three sub-messages. + +LINK\_UPPER sub-message: Indicates the route information from the node to the coordinator and each link cost. This sub-message contains the list of relay node addresses and the link cost of each link. + +LINK\_2WAY sub-message: Indicates neighbour nodes have associated with 2WAY links. This sub-message contains one or multiple sets of the target node address and its link cost. + +LINK\_LOST sub-message: Indicates a broken link. This sub-message contains one or multiple sets of the target node addresses and their link cost (must be zero). + +If the Topology Report message from a node is not received by the coordinator for a certain period, the coordinator considers the route for the node is broken. + +### 5.3.3 Route Error message + +The Route Error message is used to indicate the failure of packet delivery. If the packet is not correctly delivered to the next hop node in downstream communication, the node transmits the Route Error message to the originator (i.e., the coordinator) so that the originator can re-select the route for packet transmission. + +The Route Error message contains a LINK\_LOST sub-message that indicates the broken link(s). + +### 5.3.4 Source route header + +For source routing, the source route header is attached in the packet. The source route header contains the relay node addresses in the route to the destination. When the node receives a packet with a source route header, the node relays the packet according to the source route header. + +## 5.4 Protocol parameters + +CMSR uses the following parameters. + +HELLO\_INTERVAL: Transmission interval of Hello message. + +HELLO\_INTERVAL\_FAST: Transmission interval of Hello message in fast mode. + +HELLO\_JITTER: Jitter of Hello message transmission timing, expressed as a ratio (0~1) to HELLO\_INTERVAL (or HELLO\_INTERVAL\_FAST). + +TOPOLOGY\_REPORT\_INTERVAL: Transmission interval of Topology Report message. + +TOPOLOGY\_REPORT\_INTERVAL\_FAST: Transmission interval of Topology Report message for fast mode node. + +LINK\_MAX\_PREFERRED: Maximum number of links which can be listed as preferred link. + +HELLO\_MAX\_COUNT: Timer for absence of Hello message from a neighbour node. Used for decision of link lost. + +NOTIFY\_MAX\_COUNT: Number of Hello sub-message transmissions addressed to a certain node. + +ROUTE\_VALID\_COUNT: Timer for absence of Topology Report message from a node. Used for decision of route lost. + +# 6 Table and information base + +CMSR uses two tables, "neighbour table" and "route table", which are maintained by all nodes, including the coordinator. In addition, CMSR uses FloodingFlag, which is Boolean type flag (0: disable, 1: enable) and is used to enable or disable relay of broadcast packet for each node. + +## 6.1 Neighbour table + +The neighbour table consists of the entries shown in Table 6-1. The neighbour table may contain one or more sets of entries. + +**Table 6-1 – Neighbour table** + +| Entry | Definition | +|----------------------------------|------------------------------------------------------------------------------------------| +| Neighbour node address | 16-bit short address of the neighbour node | +| Node type | Coordinator(0), non-coordinator node(1) | +| Link status | The status of the link. 1WAY(1), 2WAY(2), LOST(3) | +| LC incoming | Link cost from the neighbour node to the node itself | +| LC outgoing | Link cost from the node itself to the neighbour node | +| LC of relay link list | Link cost of each link in the route from the neighbour node to the coordinator | +| Short address of relay node list | Short address of each relay node in the route from the neighbour node to the coordinator | +| Route cost | Route cost from the node itself to the coordinator | + +## 6.2 Route table + +The route table is shown in Table 6-2. + +**Table 6-2 – Route table** + +| Entry | Definition | +|---------------------------|---------------------------------------------------------| +| Destination short address | 16-bit short address of final-destination node | +| Route cost | Route cost from the node itself to the destination node | +| Hop count | The number of hops to the final-destination node | +| Short address list | 16-bit short addresses of relay nodes | + +# 7 Message format + +The packet format used for routing is shown in Figure 7-1. "Mesh type and header" and "broadcast type and header" use the format described in [IETF RFC 4944]. + +![Figure 7-1: Packet format diagram showing MAC and ADP layers. The MAC layer contains MHR, MAC payload, and MFR. The ADP layer contains Mesh type and header, Broadcast type and header, and ADP layer command. Dashed lines connect the MAC payload to the ADP layer components.](1b5a812c8aa20fd5cba28e97001d32de_img.jpg) + +G.9905(12)\_F7-1 + +Figure 7-1: Packet format diagram showing MAC and ADP layers. The MAC layer contains MHR, MAC payload, and MFR. The ADP layer contains Mesh type and header, Broadcast type and header, and ADP layer command. Dashed lines connect the MAC payload to the ADP layer components. + +**Figure 7-1 – Packet format** + +CMSR makes use of the ADP layer command frame header of a 6lowPAN frame [IETF RFC 4944]. The ADP layer command frame header is identified using the ESC header type [IETF RFC 6282], followed by an 8-bit command ID field and the command payload, as shown in Figure 7-2. This header must always be in the last position in the 6lowPAN frame. + +The command ID indicates that the ADP layer payload contains a CMSR protocol message. The value of the command ID used for the present Recommendation may depend on the ADP layer specification, as shown in Table 7-1. + +For a CMSR protocol message, the ADP layer payload shall contain either a source route header or a CMSR message. The CMSR message, in turn, shall contain one of three message types – Hello message, Topology Report message or Route Error message. The content is identified using the message type field at the beginning of the command payload, as shown in Table 7-1a. + +![](704082cc3e11776bda29595c76411362_img.jpg) + +| | | | +|-----------------|------------|-----------------| +| ESC header type | Command ID | Command Payload | +| 0 1 0 0 0 0 0 0 | | | +| 8 | 8 | variable (bit) | + +G.9905(13)\_F7-2 + +**Figure 7-2 – ADP command frame header** + +**Table 7-1 – Command ID used in ADP layer** + +| Command | Command ID | +|-----------------------|--------------------------------------| +| CMSR protocol message | Depending on ADP layer specification | + +**Table 7-1a – Message type** + +| Message type | Message | +|--------------|--------------------------------| +| 0x1 | CMSR message – Hello | +| 0x2 | CMSR message – Topology Report | +| 0x3 | CMSR message – Route Error | +| 0x8 | Source route header | + +## 7.1 CMSR source route header + +The source route header is used by the coordinator when sending a message to a particular node. It contains the route from the coordinator to the node and is constructed by the coordinator. The source route header contains the relay node addresses in the route to the destination. The format of the source route header is shown in Figure 7-3. The definition of the field is given in Table 7-2. + +| | | | | | | | +|-----------------------------|------------------------|--------------------------|--------------------------------------|------------------------------------------|-----------|--------------------------------------------| +| ESC header type
(8 bits) | Command ID
(8 bits) | Message type
(4 bits) | The total number of hops
(4 bits) | The first hop short address
(16 bits) | . . . . . | The (n-1)th hop short address
(16 bits) | +|-----------------------------|------------------------|--------------------------|--------------------------------------|------------------------------------------|-----------|--------------------------------------------| + +G.9905(13)\_F7-3 + +**Figure 7-3 – CMSR source route header format** + +**Table 7-2 – Source route header fields** + +| Field | Length | Definition | +|-------------------------|---------|-----------------------------------------------------------------------| +| Total number of hops | 4 bits | The number of hops from the originator to the destination node | +| First hop short address | 16 bits | Relay node address of the first hop | +| ... | ... | ... | +| Nth hop short address | 16 bits | Relay node address of the Nth hop. N denotes the total number of hops | + +The addresses of relay nodes shall be placed in order from the coordinator to the destination. + +## 7.2 CMSR message + +Three types of CMSR messages, Hello message, Topology Report message and route error message, are defined. The general format of the CMSR message is shown in Figure 7-4. The definition of the fields is given in Tables 7-3 and 7-4. + +The format of the CMSR message is shown below. + +| ESC header type | Command ID | Message type | CMSR message type dependent | Node type | Sequence number | Message | +|-----------------|------------|--------------|-----------------------------|-----------|-----------------|------------| +| (8 bits) | (8 bits) | (4 bits) | (3 bits) | (1 bit) | (8 bits) | (variable) | + +G.9905(13)\_F7-4 + +**Figure 7-4 – CMSR message format** + +**Table 7-3 – CMSR message fields** + +| Field | Length | Definition | +|-----------------------------|----------|--------------------------------------------------| +| CMSR message type dependent | 3 bits | Depends on CMSR message type, shown in Table 7-4 | +| Node type | 1 bit | 0=coordinator, 1=non-coordinator node | +| Sequence number | 8 bits | Incremented in every transmission | +| Message | Variable | Depends on message type | + +**Table 7-4 – CMSR message dependent field** + +| CMSR message | CMSR message type dependent field | +|-----------------|-------------------------------------------| +| Hello | Fast_mode flag (1 bit), reserved (2 bits) | +| Topology report | Reserved (3 bits) | +| Route error | Reserved (3 bits) | + +### 7.2.1 Hello message + +The Hello message format is shown in Figure 7-5. In the Hello message, one bit (MSB) in the CMSR message type dependent field is used as fast mode flag. The definition of the fields is given in Table 7-5. The Hello message has four sub-messages. If there is no content to be included in a sub-message, it may be omitted. The format of the sub-messages is given in Figure 7-6, with sub-message types given in Table 7-6. + +| Message type | Fast mode flag | Reserved | Node type | Sequence number | Sub-message LINK_UPPER | Sub-message LINK_REQ | Sub-message LINK_REP | Sub-message LINK_LOST | +|--------------|----------------|----------|-----------|-----------------|------------------------|----------------------|----------------------|-----------------------| +| (4 bits) | (1 bit) | (2 bits) | (1 bit) | (8 bits) | (variable) | (variable) | (variable) | (variable) | + +G.9905(13)\_F7-5 + +**Figure 7-5 – Hello message format** + +**Table 7-5 – Hello message specific field** + +| Field | Length | Definition | +|------------------------|----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Fast mode flag | 1 bit | 0=no request, 1=request fast mode | +| Reserved | 2 bits | Reserved for future use | +| LINK_UPPER sub-message | Variable | Indicates information on the route to the coordinator and link cost of each link.
Contains the following fields:
– sub-message type (shall be 0)
– number of links in the route to the coordinator
– link cost of each link in the route
– short address of each link in the route | +| LINK_REQ sub-message | Variable | Indicates a request to neighbour nodes for outgoing link cost.
Contains the following fields:
– sub-message type (shall be 1)
– number of neighbour nodes requested
– incoming link cost for the neighbour node
– short address of the neighbour node.
Multiple sets of incoming link cost and short address may be included | +| LINK_REP sub-message | Variable | Indicates a response to a LINK_REQ sub-message from neighbour nodes.
Contains the following fields:
– sub-message type (shall be 2)
– number of neighbour nodes replied
– incoming link cost for the neighbour node
– short address of the neighbour node.
Multiple sets of incoming link cost and short address may be included | +| LINK_LOST sub-message | Variable | Indicates broken links.
Contains the following fields:
– sub-message type (shall be 3)
– number of broken links
– link cost of each link (shall be set all 0)
– short address of the neighbour node associated with broken link.
Multiple sets of incoming link cost and short address may be included | + +![](76b0cd79baaedd942af4dc42f2e764b8_img.jpg) + +MSB (2 byte) LSB + +| Message type | Fast mode flag | Reserved | Node type | Sequence number | +|-----------------------------|--------------------------------------|----------|-----------|------------------| +| Sub-message
LINK_UPPER { | Sub-message type | | | Number of links | +| | Link cost #1 | | | Short address #1 | +| | The continuation of short address #1 | | | Link cost #2 | +| | . . . . . | | | . . . . . | +| Sub-message
LINK_REQ { | Sub-message type | | | Number of links | +| | Link cost #1 | | | Short address #1 | +| | The continuation of short address #1 | | | Link cost #2 | +| | . . . . . | | | . . . . . | +| Sub-message
LINK_REP { | Sub-message type | | | Number of links | +| | Link cost #1 | | | Short address #1 | +| | The continuation of short address #1 | | | Link cost #2 | +| | . . . . . | | | . . . . . | +| Sub-message
LINK_LOST { | Sub-message type | | | Number of links | +| | Link cost #1 | | | Short address #1 | +| | The continuation of short address #1 | | | Link cost #2 | +| | . . . . . | | | . . . . . | + +G.9905(13)\_F7-6 + +**Figure 7-6 – Hello message sub-message formats** + +**Table 7-6 – Sub-message type (Hello message)** + +| Sub-message type | Value | +|------------------|-------| +| LINK_UPPER | 0 | +| LINK_REQ | 1 | +| LINK_REP | 2 | +| LINK_LOST | 3 | + +### 7.2.2 Topology Report message + +The Topology Report message contains three sub messages – LINK\_UPPER, LINK\_2WAY and LINK\_LOST. The LINK\_UPPER sub-message shall always be present. The remaining messages may be omitted if there is no content to be included in them. The Topology Report message format is shown in Figure 7-7. The CMSR message type dependent field is reserved for future use. The definition of the fields is given in Table 7-8. The format of the three sub-messages is shown in Figure 7-8. The definition of sub-message type field is given in Table 7-9. + +![](8592a32c2fdf17c1e562f0ba6b7e8e1a_img.jpg) + +| Message type | Reserved | Node type | Sequence number | Sub-message
LINK_UPPER | Sub-message
LINK_2WAY | Sub-message
LINK_LOST | +|--------------|----------|-----------|-----------------|---------------------------|--------------------------|--------------------------| +| (4 bits) | (3 bits) | (1 bit) | (8 bits) | (variable) | (variable) | (variable) | + +G.9905(13)\_F7-7 + +**Figure 7-7 – Topology Report message format** + +**Table 7-8 – Topology Report message specific field** + +| Field | Length | Definition | +|------------------------|----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Reserved | 3 bits | Reserved for future use | +| LINK_UPPER sub-message | Variable | Same as LINK_UPPER sub-message field in Hello message (Table 7-6) | +| LINK_2WAY sub-message | Variable | Indicates available 2WAY links for the node.
Contains the following fields:
– sub-message type (shall be 1)
– number of 2WAY links
– link cost for the link
– short address of the neighbour node with 2WAY link.
Multiple sets of link cost and short address may be included | +| LINK_LOST sub-message | Variable | Same as LINK_LOST sub-message field in Hello message (Table 7-6) | + +![Diagram showing the sub-message formats for Topology Report message. It includes a header row with MSB, (2 byte), and LSB labels. Below are three sub-message structures: LINK_UPPER, LINK_2WAY, and LINK_LOST. Each structure starts with a 'Sub-message type' field, followed by 'Number of links', 'Link cost #1', 'Short address #1', 'The continuation of short address #1', 'Link cost #2', and a '...' field. The first row of each sub-message structure also includes 'Message type', 'Reserved', and 'Node type' fields.](2b3a967f6ce4f23649be995a353e39f8_img.jpg) + +MSB (2 byte) LSB + +| Message type | Reserved | Node type | Sequence number | +|--------------------------|--------------------------------------|-----------|------------------| +| Sub-message LINK_UPPER { | Sub-message type | | Number of links | +| | Link cost #1 | | Short address #1 | +| | The continuation of short address #1 | | Link cost #2 | +| | . . . . . | | . . . . . | +| | Sub-message type | | Number of links | +| Sub-message LINK_2WAY { | Link cost #1 | | Short address #1 | +| | The continuation of short address #1 | | Link cost #2 | +| | . . . . . | | . . . . . | +| | Sub-message type | | Number of links | +| | Link cost #1 | | Short address #1 | +| Sub-message LINK_LOST { | The continuation of short address #1 | | Link cost #2 | +| | . . . . . | | . . . . . | + +G.9905(13)\_F7-8 + +Diagram showing the sub-message formats for Topology Report message. It includes a header row with MSB, (2 byte), and LSB labels. Below are three sub-message structures: LINK\_UPPER, LINK\_2WAY, and LINK\_LOST. Each structure starts with a 'Sub-message type' field, followed by 'Number of links', 'Link cost #1', 'Short address #1', 'The continuation of short address #1', 'Link cost #2', and a '...' field. The first row of each sub-message structure also includes 'Message type', 'Reserved', and 'Node type' fields. + +**Figure 7-8 – Topology Report message sub-message formats** + +**Table 7-9 – Sub-message type (Topology Report message)** + +| Sub-message type | Value | +|------------------|-------| +| LINK_UPPER | 0 | +| LINK_2WAY | 2 | +| LINK_LOST | 3 | + +### 7.2.3 Route Error message + +The Route Error message contains the LINK\_LOST sub-message. The LINK\_LOST sub-message shall always be present. The Route Error message format is shown in Figure 7-9. The CMSR message type dependent field is reserved for future use. The definition of the fields is given in Table 7-10. The format of the sub-messages is shown in Figure 7-10. + +![](5445597cceefaca1ac89e710fe339325_img.jpg) + +| | | | | | +|--------------|----------|-----------|-----------------|-----------------------| +| Message type | Reserved | Node type | Sequence number | Sub-message LINK_LOST | +| (4 bits) | (3 bits) | (1 bit) | (8 bits) | (variable) | + +G.9905(13)\_F7-9 + +**Figure 7-9 – Route Error message format** + +**Table 7-10 – Route Error message specific field** + +| Field | Length | Definition | +|-----------------------|----------|------------------------------------------------------------------| +| Reserved | 3 bits | Reserved for future use | +| LINK_LOST sub-message | Variable | Same as LINK_LOST sub-message field in Hello message (Table 7-6) | + +![](2eb23c2210154279f8013a1594fbcc5a_img.jpg) + +| | | | | | +|-------------------------|--------------------------------------|----------|-----------|------------------| +| | MSB | (2byte) | | LSB | +| | Message type | Reserved | Node type | Sequence number | +| Sub-message LINK_LOST { | Sub-message type | | | Number of links | +| | Link cost #1 | | | Short address #1 | +| | The continuation of short address #1 | | | Link cost #2 | +| | . . . . . | | | . . . . . | + +G.9905(13)\_F7-10 + +**Figure 7-10 – Route Error message sub-message formats** + +# 8 Procedure + +## 8.1 Hello message exchange + +### 8.1.1 Generation + +Each node generates a Hello message based on the information held in its neighbour table and broadcasts it at the timing given by the following equation. + +$$t(i) = t(i-1) + \text{HELLO\_INTERVAL} (1 - \text{HELLO\_JITTER} * r) \quad (\text{Eq.1})$$ + +$t(i)$ : the timing for $i$ -th Hello message transmission + +$r$ : a random variable whose range is 0~1 + +A node in fast mode shall use $\text{HELLO\_INTERVAL\_FAST}$ instead of $\text{HELLO\_INTERVAL}$ in Eq.1. Figure 8-1 shows the Hello transmission timing. + +When a node has no route to the coordinator in its route table, the node shall enable the fast mode flag in the Hello message. + +If a node has a route to the coordinator, it shall include the LINK\_UPPER sub-message in the Hello message. A node may include the LINK\_REQ sub-message to request LC outgoing information from a neighbour node depending on the link status and the provisional route cost. Neighbour nodes with "1WAY" link status and in preferred link (i.e., having lower provisional route cost) shall be included in the LINK\_REQ sub-message. In this case, the node shall include the short address of the neighbour node and LC incoming in the neighbour table associated with the neighbour node in the LINK\_REQ sub-message. Requests to more than one neighbour node may be included in this sub-message, but shall not exceed LINK\_MAX\_PREFERRED neighbour nodes. + +If a node has received a Hello message with LINK\_REQ sub-message directed to the node from a neighbour node, the node shall include the LINK\_REP sub-message as reply to the received LINK\_REQ sub-message in the next Hello message(s). In this case, the node shall include the short address of the neighbour node and LC incoming in the neighbour table associated with the neighbour node. Replies to more than one neighbour node LINK\_REQ may be included in this sub-message. + +If a node has a neighbour node whose link status is LOST in the neighbour table, the node shall include the LINK\_LOST sub-message in the Hello message. In this case, the node shall include the short address of the neighbour node with which the link has lost. + +The LINK\_REQ sub-message, LINK\_REP sub-message and LINK\_LOST sub-message addressed to a certain neighbour node shall be transmitted NOTIFY\_MAX\_COUNT times, irrespective of fast mode or normal mode. + +![Figure 8-1 – Hello message transmission diagram showing HELLO_INTERVAL, HELLO_JITTER, HELLO_INTERVAL_FAST, NOTIFY_MAX_COUNT, and Fast mode.](a3472689858b068ef469213682965325_img.jpg) + +The diagram illustrates the transmission of Hello messages over time. A horizontal axis represents time. + +1. The first message is labeled 'HELLO'. + +2. A double-headed arrow labeled 'HELLO\_INTERVAL' spans from the first message to the start of a second transmission period. + +3. Within this period, a second 'HELLO' message is shown. A smaller double-headed arrow labeled 'HELLO\_JITTER' indicates its offset from the start of the period. Text 'Transmitted within this period' points to this message. + +4. Another 'HELLO\_INTERVAL' arrow spans from the start of the second period to the start of a third. + +5. A third 'HELLO\_INTERVAL\_FAST' arrow is shown, starting from a vertical blue arrow labeled 'Reception of Hello message with "Fast mode" flag enabled'. + +6. Within this 'HELLO\_INTERVAL\_FAST' period, three 'HELLO' messages are shown. A double-headed arrow labeled 'NOTIFY\_MAX\_COUNT' spans across them. + +7. Below these three messages is an orange bar labeled 'Fast mode'. + +8. The diagram is labeled 'time' at the far right and 'G.9905(13)\_F8-1' at the bottom right. + +Figure 8-1 – Hello message transmission diagram showing HELLO\_INTERVAL, HELLO\_JITTER, HELLO\_INTERVAL\_FAST, NOTIFY\_MAX\_COUNT, and Fast mode. + +**Figure 8-1 – Hello message transmission** + +![Flowchart for Hello message generation. The process starts with 'HELLO transmission timing', then checks if there is a route to the coordinator. If yes, it adds LINK_UPPER. If no, it enters a loop for each node in the neighbour table. For each node, it checks the link status: 1WAY, 2WAY, or LOST. Depending on the status and other conditions (preferred neighbour, transmitted counts), it adds LINK_REQ, LINK_REP, or LINK_LOST. After the loop, it checks if all nodes are done. If yes, it transmits the Hello message. If no, it increments the node index and repeats the loop.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +``` + +graph TD + Start[HELLO transmission timing] --> RouteToCoordinator{Route to coordinator?} + RouteToCoordinator -- Y --> AddLINK_UPPER[Add LINK_UPPER] + RouteToCoordinator -- N --> ForNodeI[For node i in neighbour table] + AddLINK_UPPER --> ForNodeI + ForNodeI --> LinkStatus1WAY{Link Status = 1WAY ?} + LinkStatus1WAY -- Y --> PreferredNeighbour{Preferred neighbour node?} + PreferredNeighbour -- Y --> TransmittedLINK_REQ{Transmitted LINK_REQ NOTIFY_MAX_COUNT times?} + PreferredNeighbour -- N --> LinkStatus2WAY + TransmittedLINK_REQ -- Y --> LinkStatus2WAY + TransmittedLINK_REQ -- N --> AddLINK_REQ[Add LINK_REQ] + AddLINK_REQ --> LinkStatus2WAY + LinkStatus1WAY -- N --> LinkStatus2WAY{Link Status = 2WAY ?} + LinkStatus2WAY -- Y --> ReceivedLINK_REQ{Received LINK_REQ ?} + ReceivedLINK_REQ -- Y --> TransmittedLINK_REP{Transmitted LINK_REP NOTIFY_MAX_COUNT times?} + ReceivedLINK_REQ -- N --> LinkStatusLOST + TransmittedLINK_REP -- Y --> LinkStatusLOST + TransmittedLINK_REP -- N --> AddLINK_REP[Add LINK_REP] + AddLINK_REP --> LinkStatusLOST + LinkStatus2WAY -- N --> LinkStatusLOST{Link Status = LOST ?} + LinkStatusLOST -- Y --> TransmittedLINK_LOST{Transmitted LINK_LOST NOTIFY_MAX_COUNT times?} + LinkStatusLOST -- N --> AllNodesDone{All nodes in N-tbl done?} + TransmittedLINK_LOST -- Y --> AllNodesDone + TransmittedLINK_LOST -- N --> AddLINK_LOST[Add LINK_LOST] + AddLINK_LOST --> AllNodesDone + AllNodesDone -- N --> iInc[i++] + iInc --> ForNodeI + AllNodesDone -- Y --> TransmitHello[Transmit Hello] + +``` + +Flowchart for Hello message generation. The process starts with 'HELLO transmission timing', then checks if there is a route to the coordinator. If yes, it adds LINK\_UPPER. If no, it enters a loop for each node in the neighbour table. For each node, it checks the link status: 1WAY, 2WAY, or LOST. Depending on the status and other conditions (preferred neighbour, transmitted counts), it adds LINK\_REQ, LINK\_REP, or LINK\_LOST. After the loop, it checks if all nodes are done. If yes, it transmits the Hello message. If no, it increments the node index and repeats the loop. + +G.9905(13)\_F8-2 + +**Figure 8-2 – flowchart for Hello message generation** + +### 8.1.2 Processing upon reception + +Upon receiving a HELLO message, a node shall update its neighbour table based on the contents of the Hello message and measured LC incoming using the received Hello message. The process is as follows. + +If a node receives a Hello message with fast mode flag enabled, the node shall enter fast mode. The node shall stay fast mode until the node transmits Hello messages NOTIFY\_MAX\_COUNT times. + +If the source node of the received Hello message is not in its neighbour table, the receiving node shall add a new record for the source node with neighbour node address and node type entries. + +The node shall update the LC incoming entry of the neighbour table based on measurement of the Hello message. + +If the receiving node is in the LINK\_UPPER sub-message of the received Hello message, the node shall update the FloodingFlag enabled. In this case, the node shall not select the neighbour node as a relay node in the route. + +If the receiving node is not listed in the LINK\_UPPER sub-message of the received Hello message, the node shall calculate the provisional route cost and update the "LC Relay Link List" and "Short Address of Relay Node List" entries in its neighbour table based on the contents in the LINK\_UPPER sub-message. + +If the receiving node is listed in the LINK\_REQ sub-message, the node shall update the corresponding Link Status entry to "2WAY", the corresponding LC outgoing entry to the "Link Cost" value of the LINK\_REQ sub-message and Notify Count entry to the initial value (NOTIFY\_MAX\_COUNT). + +If the receiving node is listed in the LINK\_REP sub-message, the node shall update the corresponding Link Status entry to "2WAY" and the corresponding LC outgoing entry to the "Link Cost" value of the LINK\_REP sub-message. + +If the receiving node is listed in the LINK\_LOST sub-message, the node shall update the Link Status entry to "1WAY". + +If the link status is "2WAY", the node updates the route cost field in the neighbour table according to the route information in the received LINK\_UPPER sub-message (if there is) and link cost which is calculated as the maximum of LC incoming measured by the Hello message and LC outgoing obtained from LINK\_REQ sub-message or LINK\_REP sub-message (if there is). + +The node shall select the route with the lowest route cost and may select other low cost routes to be used as alternatives in the case of route recovery. The node populates the "Hop Count" and "Short Address List" fields of its route table accordingly. + +Table 6-1 summarizes the update of neighbour table upon reception of Hello message and a flowchart is provided in Figure 8-3. + +![Flowchart for Hello message reception. The process starts with 'Node receives HELLO message'. It then checks 'Fast mode flag set'. If 'N', it goes to 'Node listed in LINK_LOST'. If 'Y', it enters 'Fast mode NOTIFY_MAX_COUNT transmissions'. Next, it checks 'Source node in neighbour node table'. If 'N', it creates a new record. If 'Y', it updates the 'LC incoming' entry. Then it checks 'Node listed in LINK_UPPER'. If 'N', it updates 'Provisional Route Cost', 'LC Relay Link', and 'Short Addr of Relay Node' entries. If 'Y', it enables the 'Flooding Flag'. All paths lead to a common junction. From this junction, the flowchart branches into two parallel paths. The left path checks 'Node listed in LINK_REQ'. If 'Y', it sets 'Link Status' to '2WAY' and updates 'LC Outgoing' from 'LINK_REQ'. If 'N', it goes to 'Node listed in LINK_LOST'. The right path checks 'Node listed in LINK_LOST'. If 'Y', it updates 'LINK_STATUS' to '1WAY'. Both paths lead to a decision 'Link status set to 2WAY'. If 'N', it goes to 'Node listed in LINK_REQ'. If 'Y', it sets 'Route Cost' to SUM(all Link Cost in LINK_UPPER) + Max(LC Incoming, LC Outgoing) and populates the route table. Both paths then lead to a common junction for 'Node listed in LINK_REQ'. If 'Y', it sets 'Link Status' to '2WAY' and updates 'LC Outgoing' from 'LINK_REQ'. If 'N', it leads to the final junction.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg) + +``` + +graph TD + Start[Node receives HELLO message] --> FastMode{Fast mode flag set} + FastMode -- N --> LinkLost{Node listed in LINK_LOST} + FastMode -- Y --> FastModeProc[Node enters Fast mode NOTIFY_MAX_COUNT transmissions] + FastModeProc --> SourceNode{Source node in neighbour node table} + SourceNode -- N --> NewRecord[Create new record in Neighbour table with neighbour node address and node type entries] + SourceNode -- Y --> UpdateLC[Update LC incoming entry in neighbour table] + UpdateLC --> LinkUpper{Node listed in LINK_UPPER} + LinkUpper -- N --> UpdateProvisional[Update "Provisional Route Cost", "LC Relay Link" and "Short Addr of Relay Node" entries in neighbour table according to LINK_UPPER contents] + LinkUpper -- Y --> EnableFlooding[Enable Flooding Flag] + NewRecord --> Junction1(( )) + UpdateProvisional --> Junction1 + EnableFlooding --> Junction1 + Junction1 --> LinkReq{Node listed in LINK_REQ} + LinkReq -- Y --> SetLinkStatus1[Set "Link Status" entry in source node record of neighbour table to "2WAY"] + SetLinkStatus1 --> SetLCOutgoing1[Set "LC Outgoing" to "Link Cost" value from LINK_REQ] + SetLCOutgoing1 --> LinkLost + LinkReq -- N --> LinkLost + LinkLost -- Y --> UpdateLinkStatus[Update LINK_STATUS entry for source node to "1WAY"] + UpdateLinkStatus --> LinkStatusSet{Link status set to "2WAY"} + LinkStatusSet -- N --> LinkReq + LinkStatusSet -- Y --> SetRouteCost[Set "Route Cost" entry to SUM(all Link Cost in LINK_UPPER) + Max(LC Incoming, LC Outgoing)] + SetRouteCost --> SelectRoute[Select route with lowest route cost and (optionally) select alternative candidate routes and populate route table "Hop Count" and "Short address list" fields accordingly] + SelectRoute --> Junction2(( )) + Junction2 --> LinkReq + LinkReq -- Y --> SetLinkStatus2[Set "Link Status" entry in source node record of neighbour table to "2WAY"] + SetLinkStatus2 --> SetLCOutgoing2[Set "LC Outgoing" to "Link Cost" value from LINK_REQ] + SetLCOutgoing2 --> FinalJunction(( )) + LinkReq -- N --> FinalJunction + +``` + +Flowchart for Hello message reception. The process starts with 'Node receives HELLO message'. It then checks 'Fast mode flag set'. If 'N', it goes to 'Node listed in LINK\_LOST'. If 'Y', it enters 'Fast mode NOTIFY\_MAX\_COUNT transmissions'. Next, it checks 'Source node in neighbour node table'. If 'N', it creates a new record. If 'Y', it updates the 'LC incoming' entry. Then it checks 'Node listed in LINK\_UPPER'. If 'N', it updates 'Provisional Route Cost', 'LC Relay Link', and 'Short Addr of Relay Node' entries. If 'Y', it enables the 'Flooding Flag'. All paths lead to a common junction. From this junction, the flowchart branches into two parallel paths. The left path checks 'Node listed in LINK\_REQ'. If 'Y', it sets 'Link Status' to '2WAY' and updates 'LC Outgoing' from 'LINK\_REQ'. If 'N', it goes to 'Node listed in LINK\_LOST'. The right path checks 'Node listed in LINK\_LOST'. If 'Y', it updates 'LINK\_STATUS' to '1WAY'. Both paths lead to a decision 'Link status set to 2WAY'. If 'N', it goes to 'Node listed in LINK\_REQ'. If 'Y', it sets 'Route Cost' to SUM(all Link Cost in LINK\_UPPER) + Max(LC Incoming, LC Outgoing) and populates the route table. Both paths then lead to a common junction for 'Node listed in LINK\_REQ'. If 'Y', it sets 'Link Status' to '2WAY' and updates 'LC Outgoing' from 'LINK\_REQ'. If 'N', it leads to the final junction. + +Figure 8-3 – Flowchart for Hello message reception + +## 8.2 Topology report message transmission + +### 8.2.1 Generation + +The non-coordinator node shall transmit a Topology Report message as an unicast message at an interval given by TOPOLOGY\_REPORT\_INTERVAL. For the non-coordinator node in fast mode, the interval is given by TOPOLOGY\_REPORT\_INTERVAL\_FAST. The non-coordinator node shall generate a Topology Report message based on information contained in its route table and neighbour table. + +### 8.2.2 Processing upon reception + +For a non-coordinator node, if a node receives a Topology Report message from a neighbour node, the node shall relay the message to the next hop toward the coordinator according to its routing table. If hop-by-hop routing is to be used for downstream packet transmission, a node shall store the downward route information in the route table according to the information contained in the LINK\_UPPER sub-message. + +If the coordinator node receives a Topology Report message and the final-destination of the LINK\_UPPER sub-message is its own address, the coordinator node shall perform the following. + +- Create new record for the source node in the route table if the source node is not in the route table. +- Calculate the route cost from link cost information in the LINK\_UPPER sub-message and update the route cost entry to the new calculated value. +- Populate the "hop count" and "short address list" entries of the route table according to information contained in the LINK\_UPPER sub-message. + +The information indicated in the LINK\_2WAY sub-message and/or LINK\_LOST sub-message may be used for alternative route generation or route change. + +## **8.3 Route Error message transmission** + +If the transmission of a packet whose source node is the coordinator (i.e., downstream communication) has failed, the node shall generate a Route Error message with LINK\_LOST sub-message containing the broken link. The node shall transmit the Route Error message to the next hop node in the upstream. + +## **8.4 Link break determination** + +The coordinator and the non-coordinator node shall detect the link breaks in the following way. If no Hello message is received from a neighbour node for a pre-defined period, the node shall assume that a link break has occurred and shall update the link status to "LOST" in the neighbour table record for the node. The period for the link break is given by the value of HELLO\_INTERVAL multiplied by HELLO\_MAX\_COUNT. + +## **8.5 Route break determination** + +The coordinator node shall detect the route breaks in the following way. If no Topology Report message is received from a node for a pre-defined period, the coordinator node shall assume that a route break has occurred. The period for the route break is given by the value of TOPOLOGY\_REPORT\_INTERVAL multiplied by ROUTE\_VALID\_COUNT. The coordinator node may update the corresponding route information to the alternative route or delete the corresponding route information in the route table. + +# **9 Packet transmission** + +## **9.1 Unicast packet** + +### **9.1.1 Generation** + +For the coordinator node, two methods of packet transmission, source routing and hop-by-hop routing, are possible. The coordinator may select source routing or hop-by-hop routing according to system requirements. + +If source routing is used, the coordinator node shall generate the CMSR source route header (SRH) according to the route information to the final-destination in the route table. The coordinator node shall attach the SRH to the packet. Upon reception of the packet with the SRH, the node shall relay the packet including SRH to the next hop node according to the route indicated in the SRH. If the next hop node is the final-destination node, the node may omit the SRH. + +If hop-by-hop routing is used, the coordinator shall transmit the packet without SRH to the next hop. Upon reception of the packet without SRH, the node shall relay the packet to the next hop node based on the route information stored in its route table. The final-destination address shall be described in the mesh type and header. + +If the source node is a non-coordinator node, hop-by-hop routing is used. The node shall transmit the packet to the next hop node toward the coordinator based on the route information in the route table. + +### 9.1.2 Processing upon reception + +If a received packet is a unicast packet addressed to the receiving node, the node shall pass the packet to the higher layer. If not, and HopsLft in the mesh type and header is greater than one, then the node relays the packet to the next hop in accordance with the SRH attached to the packet. If the SRH is not attached, the node relays in accordance with its route table. If the destination is not on the route table, the node discards the packet. The coordinator shall not relay packets. + +## 9.2 Broadcast/multicast packet + +Upon reception of a broadcast/multicast packet, if the FloodingFlag is enabled, the node shall forward the broadcast/multicast packet. Otherwise, the node shall not forward the broadcast/multicast packet. + +# 10 Configuration parameters + +The default values of the parameters used in CMSR are summarized in Table 10-1. + +**Table 10-1 – Default values of the parameters used in CMSR** + +| Parameter name | Value | +|--------------------------|-------| +| HELLO_INTERVAL | 300 s | +| HELLO_INTERVAL_FAST | 60 s | +| HELLO_JITTER | 0.1 | +| TOPOLOGY_REPORT_INTERVAL | 900 s | +| LINK_MAX_PREFERRED | 3 | + +# Annex A + +## Routing procedure for ITU-T G.9903 + +(This annex forms an integral part of this Recommendation.) + +If Recommendation ITU-T G.9905 is used as the layer 2 routing protocol for [ITU-T G.9903] in place of LOADng, this annex shall apply. + +## A.1 Defining parameter + +An ADP layer IB attribute adpDisableDefaultRouting shall be defined in addition to the attributes defined in Table 9-25 of [ITU-T G.9903]. + +**Table A.0 – Additional adaptation sublayer IB attribute** + +| Attribute | Identifier | Type | Read only | Range | Description | Default | +|--------------------------|------------|---------|-----------|---------------|--------------------------------------------------------------------------------------------------------------------------------------------|---------| +| adpDisableDefaultRouting | 0xF0 | Boolean | No | FALSE
TRUE | If TRUE, the default routing (behaviour specified in clause 9.4.3 of [ITU-T G.9903]) is disabled. If FALSE, the default routing is enabled | FALSE | + +The Command ID in the ADP command frame header shall be used according to Table A.1. + +**Table A.1 – Command frame header identifier** + +| Command | Command ID | Comments | +|-----------------------|------------|---------------------------------------------------| +| CMSR protocol message | 0x10 | Use for CMSR source route header and CMSR message | + +## A.2 Mesh routing + +Instead of clause 9.4.3 "Mesh routing" of [ITU-T G.9903], the following procedures for L2 routing in the ADP layer shall be applied. + +### A.2.1 Packet routing + +#### A.2.1.1 Unicast packet routing + +The routing of the unicast packet is performed using the following algorithm on receipt of an MCPS-DATA.indication from the MAC layer: + +- IF (MAC destination address == address of device) + - IF (command ID in command frame header == 0x10) + - The packet is handled by the non-default routing entity. + - ELSE + - IF (No Mesh header present in 6lowPAN headers) + - Generate an ADPD-DATA.indication primitive to indicate the arrival of a frame to the upper layer, with the following characteristics (see clause 9.4.6.1.4 of [ITU-T G.9903]): + - DstAddrMode = 0x02 + +- DstAddr = MAC destination address +- SrcAddr = MAC source address +- Nsdulength = length of the payload +- Nsdulength = the payload +- LinkQualityIndicator = msduLinkQuality (see clause 9.3.11.2 of [ITU-T G.9903]) +- IF (6LoWPAN destination address == 6LoWPAN address of device) + - Generate an ADPD-DATA.indication primitive to indicate the arrival of a frame to the upper layer, with the following characteristics (see clause 9.4.6.1.4 of [ITU-T G.9903]): + - DstAddrMode = 0x02 + - DstAddr = 6LoWPAN destination address + - SrcAddr = The originator address in the 6LoWPAN mesh header + - Nsdulength = length of the payload + - Nsdulength = the payload + - LinkQualityIndicator = msduLinkQuality (see clause 9.3.11.2 of [ITU-T G.9903]) +- ELSE + - The packet is handled by the non-default routing entity. +- ELSE IF (MAC Destination address == 0xFFFF) + - This is a broadcast frame: execute algorithm described in clause A.2.1.2.1. +- ELSE + - Drop the frame. + +#### A.2.1.2 Multicast/broadcast + +##### A.2.1.2.1 Packet routing + +The packet routing mechanism is based on section 11.1 of [IETF RFC 4944]. This clause details more precisely the routing of broadcast and multicast packets. + +As described in section 11.1 of [IETF RFC 4944], each broadcast packet has a BC0 header containing a sequence number. Each time a node sends a broadcast packet, it shall increment this sequence number. + +Each node shall have a broadcast log table. This table is used for routing broadcast packets and each entry contains the parameters described in Table 9-28 of [ITU-T G.9903]. + +Each time a device receives a broadcast address with a HopsLft field of a mesh header (see section 5.2 of [IETF RFC 4944]) strictly greater than 0, it shall check if an entry already exists in the broadcast log table having the same SrcAddr and SeqNumber. If an entry exists, the received frame is silently discarded. Otherwise, a new entry is added in the table and the TimeToLive field is initialized with the value adpBroadcastLogTableEntryTTL (see clause 9.4.2 of [ITU-T G.9903]). When this value reaches 0, the entry is removed from the broadcast log table. + +When a device receives a broadcast frame, so that it has to create an entry in the broadcast log table, it shall decrement its HopsLft field. If HopsLft is not zero, the received broadcast frame is handled by the non-default routing entity. + +This can be summarized by the following algorithm, executed upon receipt of a frame whose destination address is 0xFFFF: + +IF (final destination address = broadcast address) or (final destination address is found in adpGroupTable): + +- IF (command ID in command frame header == 0x10) + - The packet is handled by the non-default routing entity +- ELSE + - IF ((SrcAddr, SeqNumber) exists in broadcast log table) + - Discard frame + - ELSE + - Create one entry (SrcAddr, SeqNumber, adpBroadcastLogTableEntryTTL) in the broadcast log table, with the corresponding frame characteristics. + - Generate an ADPD-DATA.indication primitive to the upper layer with the following characteristics: + - DstAddrMode = 0x02 + - DstAddr = Destination address in the 6LoWPAN mesh header (multicast or broadcast address) + - SrcAddr = The originator address in the 6LoWPAN mesh header + - NsduLength = length of the data + - Nsdu = the data + - LinkQualityIndicator = msduLinkQuality (see clause 9.3.11.2 of [ITU-T G.9903]) + - HopsLft=HopsLft –1 + - If (HopsLft > 0) + - The packet is handled by the non-default routing entity. + +NOTE – In case of a multicast address, the broadcast address 0xFFFF is used at the MAC level as mentioned in section 3 of [IETF RFC 4944]. Multicast frames are routed using the same algorithm as broadcast frames. + +The broadcast log table is available in the information base with the attribute adpBroadcastLogTable (see clause 9.4.2 of [ITU-T G.9903]). + +##### A.2.1.2.2 Groups + +Each device can belong to one or more groups of devices. The IB attribute adpGroupTable (see clause 9.4.2 of [ITU-T G.9903]) stores a list of 16-bit group addresses. + +When the device receives a MAC broadcast message and if the final destination address in the 6LoWPAN mesh header is equal to one of the 16-bit group addresses in adpGroupTable, then an ADPD-DATA.indication primitive is generated to the upper layer (as described in clause 9.4.3.2.2.1 of [ITU-T G.9903]). + +Groups can be added or removed from the adpGroupTable using the ADPM-SET.request primitive. The size of this table is implementation specific and shall have at least one entry. The way groups are managed by upper layers is beyond the scope of this Recommendation. + +## A.3 Transmission of IPv6 packet triggered by ADPD-DATA primitive + +The following table shall be applied for packet transmission triggered by the ADPD-DATA primitive. + +**Table A.2 – Selections from clause 9.4.6.1.2 of [ITU-T G.9903]** + +| Clause | Title and remarks/modifications | Statement | +|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------| +| 9.4.6.1.2 | ADPD-DATA.request | N | +| 9.4.6.1.2.1 | Semantics of the service primitive | N | +| 9.4.6.1.2.2 | When generated | N | +| 9.4.6.1.2.3 | Effect on reception
– Once the 6LoWPAN frame is constructed, the frame is handled by the non-default routing entity for both unicast and broadcast/multicast case | E(Extension) | + +## A.4 Packet transmission and reception triggered by non-default routing entity + +The non-default routing entity may issue a request of packet transmission. In this case, the packet shall be transferred to the MAC layer by invoking the MCPS-Data.request primitive with the following parameters: + +- SrcAddrMode = 0x02, for 16-bit address +- DstAddrMode = 0x02, for 16-bit address +- SrcPANId = DstPANId = the value of macPANId obtained from the MAC PIB +- SrcAddr = the value of macShortAddr obtained from the MAC PIB +- DstAddr = the 16-bit address of the next hop determined by the non-default routing entity +- msduLength = the length of the frame, or fragment in the case of fragmentation, in bytes +- msdu = the frame itself +- msduHandle = NsduHandle +- TxOptions: b0 = 1 +- SecurityLevel = dpSecurityLevel +- KeyIdMode, KeySource: Ignored +- KeyIndex: Ignored if SecurityLevel=0; otherwise it depends on the security policy. + +The non-default routing entity may also issue a request to transfer the received packet to the upper layer. In this case, the packet (after 6lowPAN procedure) shall be transferred to the upper layer by invoking the ADPD-DATA.indication with the following parameters: + +- DstAddrMode = 0x02 +- DstAddr = MAC destination address +- SrcAddr = MAC source address +- NsduLength = length of the payload +- Nsdu = the payload +- LinkQualityIndicator = msduLinkQuality (see clause 9.3.11.2 of [ITU-T G.9903]) + +Necessary information is provided by the non-default routing entity. + +## A.5 Interface between the ITU-T G.9903 adaptation layer and ITU-T G.9905 + +NON-DEF-ROUTING-MSG command message may be used as the interface with non-default routing entity. + +- NON-DEF-ROUTING-MSG.request + +This command is generated by non-default routing entity to transfer a data frame to the ADP layer. + +- NON-DEF-ROUTING-MSG.confirm + +This command is generated by the ADP layer to notify the results of a previous NON-DEF-ROUTING-MSG.request command to the non-default routing entity. + +- NON-DEF-ROUTING-MSG.indication + +This command is generated by the ADP layer to transfer a data frame to non-default routing entity. + +### A.5.1 NON-DEF-ROUTING-MSG.request + +NON-DEF-ROUTING-MSG.request ( + +    MacDstAddr, +     MacSrcAddr, +     NsduLength +     Nsdu +     NsduHandle +     QualityOfService +     RouteError + ) + +| Name | Type | Valid range | Description | +|------------------|---------------|---------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| MacDstAddr | Integer | 0x0000-0xFFFF | Destination address:
– next hop address determined by the non-default routing entity in case of transmission packet
– MAC destination address in case of received packet | +| MacSrcAddr | Integer | 0x0000-0xFFFF | Source address:
– MAC source address in case of received packet
– short address of own node in case of transmission packet | +| NsduLength | Integer | 0-1280 | The size of the NSDU, in bytes | +| Nsdu | Set of octets | – | The NSDU | +| NsduHandle | Integer | 0x00-0xFF | The handle of the NSDU | +| QualityOfService | Integer | 0x00-0x01 | The requested quality of service (QoS) of the frame to send. Allowed values are:
0x00 = normal priority
0x01 = high priority | +| RouteError | Boolean | FALSE, TRUE | TRUE if the packet is for transmission but the next hop information is not available | + +NOTE – If MacSrcAddr is the short address of own node, the ADP layer may consider the packet is for transmission. If not, the ADP layer may consider the packet is for reception. + +### A.5.1 NON-DEF-ROUTING-MSG.confirm + +NON-DEF-ROUTING-MSG.confirm ( +    Status, +    NsduHandle +) + +| Name | Type | Valid range | Description | +|------------|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------| +| Status | Enum | SUCCESS,
INVALID_IPV6_FRAME,
INVALID_REQUEST, NO_KEY,
BAD_CCM_OUTPUT,
ROUTE_ERROR,
BT_TABLE_FULL,
FRAME_NOT_BUFFERED or any
status values returned from security
suite or the MCPS-DATA.confirm
primitive | The status code of a previous NON-DEF-ROUTING-MSG.request identified by its NsduHandle | +| NsduHandle | Integer | 0x00-0xFF | The handle of the NSDU confirmed by this command | + +### A.5.2 NON-DEF-ROUTING-MSG.indication + +NON-DEF-ROUTING-MSG.indication ( +    MacDstAddr, +    MacSrcAddr +    NsduLength +    Nsdu +    NsduHandle +    LinkQualityIndicator +    Retry +) + +| Name | Type | Valid range | Description | +|----------------------|---------------|-------------------|---------------------------------------------------------------| +| MacDstAddr | Integer | 0x0000-
0xFFFF | destination address | +| MacSrcAddr | Integer | 0x0000-
0xFFFF | source address | +| NsduLength | Integer | 0-1280 | The size of the NSDU, in bytes | +| Nsdu | Set of Octets | – | The NSDU | +| NsduHandle | Integer | 0x00-0xFF | The Handle of the NSDU | +| LinkQualityIndicator | Integer | 0x00-0xFF | The value of the link quality during reception of the frame | +| Retry | Boolean | FALSE, TRUE | TRUE if the corresponding packet is retry packet in ADP layer | + +When the ADP layer transfers a transmission packet (i.e., either an IPv6 packet originating from the node itself or a retry packet) to the non-default routing entity, the following parameters shall be set. + +- DstAddr = next hop address used for the latest transmission of the corresponding packet if RetryFlag is set to TRUE, otherwise any value +- SrcAddr = the short address of the own node +- NsduLength = length of the payload +- Nsdu = the payload including ADP header +- LinkQualityIndicator = Any +- RetryFlag = TRUE if the packet is retry packet, otherwise FALSE. + +When the ADP layer transfers the received packet to the non-default routing entity, the following parameters shall be set. + +- DstAddr = MAC destination address of the received packet +- SrcAddr = MAC source address of the received packet +- NsduLength = length of the payload +- Nsdu = the payload including ADP header +- LinkQualityIndicator = msduLinkQuality (see clause 9.3.11.2 of [ITU-T G.9903]) +- RetryFlag = FALSE. + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.991.1-199810-I_PDF-E/raw.md b/marked/G/T-REC-G.991.1-199810-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..bac22150fc672aff511e2d67265bacd1cc5a691d --- /dev/null +++ b/marked/G/T-REC-G.991.1-199810-I_PDF-E/raw.md @@ -0,0 +1,5681 @@ + + +![ITU logo: A globe with the letters ITU and a lightning bolt.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with the letters ITU and a lightning bolt. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.991.1** + +(10/98) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital sections and digital +line system – Access networks + +--- + +**High bit rate Digital Subscriber Line (HDSL) +transceivers** + +ITU-T Recommendation G.991.1 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| Radiotelephone circuits | G.450–G.469 | +| Links with mobile stations | G.470–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +# **HIGH BIT RATE DIGITAL SUBSCRIBER LINE (HDSL) TRANSCEIVERS** + +## **Summary** + +This Recommendation specifies a High bit rate Digital Subscriber Line (HDSL) which is a bidirectional and symmetrical transmission system that allows the transport of signals with a bit rate of 1544 kbit/s or 2048 kbit/s on the copper twisted pairs of an access network. The basic work has been carried out in the ANSI T1 committee for 1544 kbit/s signals. The results of this work were taken by TM6 of ETSI and adopted for 2048 kbit/s signals in a technical specification, which built the basis for this Recommendation. + +The HDSL system uses echo cancellation technique for the separation of the directions of transmission, so that one twisted pair can carry both directions. Two different options for the line code are recommended, the Pulse Amplitude Modulation 2B1Q and the Carrierless Amplitude/Phase Modulation CAP. CAP is applicable for 2048 kbit/s only, while for 2B1Q two different frames for 1544 kbit/s and 2048 kbit/s are defined. + +The 2B1Q for 2048 kbit/s caters for both duplex transmission on a single pair and parallel transmission on two or three-pairs. This allows for the distribution of the signal to several pairs and for reduction of the symbol rate and an increase of the line length. CAP is defined for one- or two-pairs only and the 1544 kbit/s 2B1Q for two-pairs only. + +###### **Source** + +ITU-T Recommendation G.991.1 was prepared by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 13th of October 1998. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation the term *recognized operating agency (ROA)* includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms *Administration*, *ROA* and *public correspondence* are defined in the *Constitution of the ITU (Geneva, 1992)*. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 1999 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | Page | +|-----------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References ..... | 1 | +| 3 Abbreviations ..... | 2 | +| 4 Reference configuration and functional description..... | 3 | +| 5 HDSL core specification ..... | 6 | +| 5.1 Functions ..... | 6 | +| 5.1.1 Transparent transport of core frames ..... | 7 | +| 5.1.2 Stuffing and destuffing..... | 7 | +| 5.1.3 CRC-6 procedures and transmission error detection ..... | 7 | +| 5.1.4 Error reporting..... | 7 | +| 5.1.5 Failure detection..... | 7 | +| 5.1.6 Failure reporting..... | 7 | +| 5.1.7 Bit timing ..... | 7 | +| 5.1.8 Frame alignment..... | 7 | +| 5.1.9 HDSL transceiver autonomous start-up control..... | 7 | +| 5.1.10 Loopback control and coordination..... | 8 | +| 5.1.11 Mapping between core frames and HDSL frames ..... | 8 | +| 5.1.12 Control of the maintenance channel..... | 8 | +| 5.1.13 Synchronization and coordination of HDSL transceivers..... | 8 | +| 5.1.14 Identification of pairs ..... | 8 | +| 5.1.15 Correction of pair identification..... | 8 | +| 5.1.16 Remote power feeding ..... | 8 | +| 5.1.17 Wetting current..... | 8 | +| 5.2 Transmission medium ..... | 8 | +| 5.2.1 Description ..... | 8 | +| 5.2.2 Minimum Digital Local Line (DLL) requirements for HDSL applications.. | 9 | +| 5.2.3 DLL physical characteristics..... | 9 | +| 5.2.4 DLL electrical characteristics..... | 10 | +| 5.3 Transmission method ..... | 11 | +| 5.3.1 General ..... | 11 | +| 5.3.2 Transmission on three-pairs ..... | 12 | +| 5.3.3 Transmission on two-pairs ..... | 12 | +| 5.3.4 Transmission on one-pair..... | 12 | +| 5.3.5 Transmission on four-pairs ..... | 12 | +| 5.3.6 Line code..... | 12 | +| 5.3.7 Line symbol rate..... | 13 | + +| | Page | | +|-------|---------------------------------------------------------------|----| +| 5.4 | Frame structure..... | 13 | +| 5.4.1 | Core frame..... | 13 | +| 5.4.2 | 2B1Q HDSL frame..... | 14 | +| 5.4.3 | Scrambling method ..... | 27 | +| 5.5 | HDSL embedded operations channel (eoc)..... | 29 | +| 5.5.1 | Functions of the HDSL eoc..... | 30 | +| 5.5.2 | HDSL eoc acknowledgement protocol ..... | 31 | +| 5.5.3 | The HDSL eoc data read/write mode..... | 33 | +| 5.5.4 | HDSL eoc-message list..... | 36 | +| 5.5.5 | HDSL eoc-message set requirements..... | 37 | +| 5.5.6 | Data registers in the NTU and in regenerators..... | 39 | +| 5.5.7 | Noise margin ..... | 40 | +| 5.6 | Start-up procedure ..... | 41 | +| 5.6.1 | General ..... | 41 | +| 5.6.2 | Control and status signals ..... | 42 | +| 5.6.3 | Transmitted signals ..... | 43 | +| 5.6.4 | Timers ..... | 44 | +| 5.6.5 | Activation state diagrams..... | 45 | +| 5.6.6 | Regenerator related procedures..... | 51 | +| 5.7 | Operation and maintenance ..... | 55 | +| 5.7.1 | Functions at the LTU external OAM reference point ..... | 55 | +| 5.7.2 | Functions at the NTU external OAM reference point..... | 56 | +| 5.7.3 | OAM messages and functions supported by the HDSL core..... | 57 | +| 5.7.4 | Power feeding related OAM functions..... | 59 | +| 5.7.5 | Regenerator behaviour ..... | 59 | +| 5.8 | Electrical characteristics of a single 2B1Q transceiver ..... | 60 | +| 5.8.1 | General ..... | 60 | +| 5.8.2 | Transmitter/receiver impedance and return loss ..... | 60 | +| 5.8.3 | Transceiver reference clock ..... | 62 | +| 5.8.4 | Transmitter output characteristics ..... | 62 | +| 5.8.5 | Unbalance about earth..... | 66 | +| 5.9 | Performance of individual HDSL transceivers..... | 69 | +| 5.9.1 | Performance requirements ..... | 69 | +| 5.9.2 | DLL physical models (test loops) ..... | 69 | +| 5.9.3 | Jitter and wander ..... | 69 | +| 6 | Common circuitry specification ..... | 70 | +| 6.1 | Delay difference buffer..... | 70 | + +| | Page | | +|-----------|----------------------------------------------------------------------|----| +| 6.2 | The pair identification mechanism..... | 71 | +| 6.2.1 | Pair identification initial values ..... | 71 | +| 6.2.2 | Pair identification at the NTU ..... | 71 | +| 6.2.3 | Pair identification at the LTU ..... | 71 | +| 6.3 | Laboratory performance measurements ..... | 72 | +| 6.3.1 | General ..... | 72 | +| 6.3.2 | Test configuration ..... | 73 | +| 6.3.3 | Test procedure with shaped noise ..... | 77 | +| 6.3.4 | Test procedure for impulse noise ..... | 78 | +| 6.3.5 | Common mode rejection test ..... | 80 | +| 6.3.6 | Micro interruption test ..... | 80 | +| 7 | Power feeding..... | 81 | +| 7.1 | General ..... | 81 | +| 7.2 | Wetting current..... | 81 | +| 7.3 | Remote power feeding aspects..... | 81 | +| 7.3.1 | Remote power feeding aspects at the LTU ..... | 82 | +| 7.3.2 | Remote power feeding aspects at the NTU ..... | 82 | +| 7.3.3 | Remote power feeding aspects at the regenerator..... | 82 | +| 8 | Environmental requirements ..... | 82 | +| 8.1 | Climatic conditions ..... | 82 | +| 8.2 | Safety..... | 83 | +| 8.3 | Overvoltage protection..... | 83 | +| 8.4 | Electromagnetic compatibility (EMC) ..... | 83 | +| Annex A – | Transmission system for 1544 kbit/s two-pair system application..... | 83 | +| A.1 | Frame structure of the two-pair system for 784 kbit/s..... | 83 | +| Annex B – | High bit rate Digital Subscriber Line (HDSL) CAP based system..... | 86 | +| B.1 | Scope and general information..... | 86 | +| B.1.1 | Scope..... | 86 | +| B.2 | References ..... | 86 | +| B.3 | Abbreviations ..... | 86 | +| B.4 | Reference configuration and functional description..... | 87 | +| B.5 | HDSL core specification ..... | 87 | +| B.5.1 | Functions..... | 87 | +| B.5.2 | Transmission medium ..... | 87 | +| B.5.3 | Transmission method ..... | 87 | +| B.5.4 | Frame structure..... | 93 | + +| | Page | +|-------------------------------------------------------------------------------------------------------------------|-------------| +| B.5.5 HDSL embedded operations channel (eoc)..... | 100 | +| B.5.6 Start-up procedure..... | 100 | +| B.5.7 Operation and maintenance..... | 118 | +| B.5.8 Electrical characteristics of CAP-based transceivers..... | 119 | +| B.5.9 Performance of individual HDSL transceivers ..... | 123 | +| B.6 Common circuitry specification ..... | 125 | +| B.6.1 Delay difference buffer ..... | 125 | +| B.6.2 Laboratory performance measurement tests..... | 125 | +| B.7 Power feeding..... | 128 | +| B.8 Environmental requirements ..... | 128 | +| Appendix I – Application specific examples..... | 128 | +| I.1 Application specific requirements for ISDN PRA with 2048 kbit/s ..... | 128 | +| I.1.1 Mapping of 2048 kbit/s to HDSL..... | 128 | +| I.1.2 Mapping of HDSL maintenance functions to the interface..... | 128 | +| I.1.3 Performance ..... | 129 | +| I.2 Application specific requirements for the European 2048 kbit/s digital unstructured leased line (D2048U)..... | 132 | +| I.2.1 Application interfaces ..... | 132 | +| I.2.2 Mapping of the D2048U signal to HDSL ..... | 132 | +| I.2.3 Mapping of HDSL maintenance functions to the interface..... | 132 | +| I.2.4 Performance ..... | 133 | +| I.3 Application specific requirements for the European 2048 kbit/s digital structured leased line (D2048S) ..... | 134 | +| I.3.1 Application interfaces ..... | 134 | +| I.3.2 Mapping of the D2048S signal to HDSL..... | 135 | +| I.3.3 Mapping of HDSL maintenance functions to the interface..... | 135 | +| I.3.4 Performance ..... | 136 | +| I.4 Application specific requirements for fractional installation..... | 137 | +| I.4.1 Mapping of fractional services to HDSL ..... | 137 | +| I.4.2 Mapping of HDSL maintenance functions to the interface..... | 143 | +| I.4.3 Performance ..... | 144 | +| I.5 Application specific requirements for partial operation..... | 144 | +| I.5.1 Mapping of the application frame for partial operation application ..... | 144 | +| I.5.2 Mapping of HDSL maintenance functions to the interface..... | 147 | +| I.5.3 Performance ..... | 147 | +| I.5.4 Remote power feeding ..... | 148 | +| I.5.5 Partial failure criteria..... | 148 | + +| | Page | +|---------------------------------------------------------------------------------------|-------------| +| I.5.6 Action following partial failure..... | 148 | +| I.5.7 Time slot prioritization/reallocation..... | 148 | +| I.6 Application specific requirements for the 2048 kbit/s mapped into TU-12 structure | 149 | +| I.6.1 Reference Configuration..... | 149 | +| I.6.2 Application Interfaces..... | 149 | +| I.6.3 Mapping of application frame into HDSL using TU-12 structure..... | 149 | +| I.6.4 Mapping of HDSL maintenance functions to the interface..... | 153 | +| I.6.5 Performance ..... | 153 | +| Appendix II – Detailed definition of cable characteristics and test loops ..... | 155 | +| II.1 Typical characteristics of cables..... | 155 | +| II.2 Theoretical characteristics of test loops for Y = 31 dB at 150 kHz ..... | 157 | +| Appendix III – Bibliography..... | 159 | + + + +# **HIGH BIT RATE DIGITAL SUBSCRIBER LINE (HDSL) TRANSCEIVERS** + +*(Geneva, 1998)* + +# **1 Scope** + +This Recommendation describes a transmission technique called High bit rate Digital Subscriber Line (HDSL), as a means for the transportation of several types of applications. This Recommendation defines the requirements for the individual HDSL transmission system, the transmission performance, the HDSL maintenance requirements and procedures. + +An individual HDSL transceiver system is a two-wire bidirectional transceiver for metallic wires using the echo cancellation method. Three systems may be utilized, one transporting a bit rate of 784 kbit/s over each of two or three-pairs used in parallel, a second with an increased bit rate of 1168 kbit/s and two-pairs in parallel only, and a third with a more increased bit rate of 2320 kbit/s on one-pair only. + +The line code of systems specified in this Recommendation is 2B1Q and CAP. The implementor may choose one or the other of these alternatives, only one line code has to be realized in a transmission system. + +In the main body of this Recommendation, system with 2B1Q for 2048 kbit/s applications are described. In Annex A, the Committee T1 recommendation for the frame structure of 1544 kbit/s applications on two-pairs is described. Systems using a CAP line code are covered in Annex B. + +This Recommendation defines the common circuitry for combining and controlling one, two or three HDSL transceiver systems, depending on the bit rate of the transceiver system used. The common circuitry and the necessary number of HDSL transceiver systems form the HDSL core, which is independent from the possible applications. + +This Recommendation does not specify all the requirements for the implementation of NTU, LTU or REG. It serves only to describe the functionality needed. + +Examples for applications of HDSL are given in Appendix I. + +# **2 References** + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- [1] ITU-T Recommendation G.962 (1993), *Access digital section for ISDN primary rate at 2048 kbit/s.* +- [2] ITU-T Recommendation G.960 (1993), *Access digital section for ISDN basic rate access.* +- [3] ITU-T Recommendation I.431 (1993), *Primary rate user-network interface; Layer 1 specification.* +- [4] CCITT Fascicle I.3 (1988), *Terms and definitions.* + +- [5] IEC 60721-3 (1984), *Classification of environmental conditions. Part 3: Classification of groups of environmental parameters and their severities. Introduction.* +- [6] IEC 60950 (1991), *Safety of information technology equipment.* +- [7] CCITT Recommendation K.17 (1998), *Tests on power-fed repeaters using solid-state devices in order to check the arrangement for protection from external interference.* +- [8] ITU-T Recommendation K.20 (1996), *Resistibility of telecommunication switching equipment to overvoltages and overcurrents.* +- [9] ITU-T Recommendation K.21 (1996), *Resistibility of subscriber's terminal to overvoltages and overcurrents.* +- [10] CISPR 22 (1997), *Information technology – Radio disturbance characteristics – Limits and methods of measurement.* + +# 3 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|----------|----------------------------------------------------------------------------------| +| 2B1Q | two binary one quaternary line code | +| AIS | Alarm Indication Signal | +| BER | Bit Error Ratio | +| BERTS | Bit Error Ratio Test Set | +| BT | Bridged Tap, an unterminated twisted pair section bridged across the line | +| CAP | Carrierless Amplitude/Phase modulation | +| CRC | Cyclic Redundancy Check | +| DC | Direct Current | +| DLL | Digital Local Line | +| EMC | Electromagnetic Compatibility | +| eoc | Embedded Operation Channel | +| ETS | European Telecommunication Standard | +| ETSI | European Telecommunication Standards Institute | +| HDSL | High bit rate Digital Subscriber Line | +| HOH | HDSL Overhead | +| ISDN-BA | Integrated Services Digital Network – Basic Access | +| ISDN-PRA | Integrated Services Digital Network Primary Rate Access | +| ITU-T | International Telecommunication Union – Telecommunication Standardization Sector | +| IUT | Item Under Test | +| LCL | Longitudinal Conversion Loss | +| LFA | Loss of Frame Alignment | +| LOS | Loss Of Signal | +| LSB | Least Significant Bit | + +| | | +|--------|--------------------------------------| +| LTU | Line Termination Unit | +| MSB | Most Significant Bit | +| MTIE | Maximum Time Interval Error | +| NEXT | Near-End crosstalk | +| NNI | Network Node Interface | +| NTU | Network Termination Unit | +| OAM | Operation And Maintenance | +| PRBS | Pseudo-Random Bit Sequence | +| PSD | Power Spectral Density | +| PSL | Power Sum Loss | +| r.m.s. | Root mean square | +| REG | Regenerator | +| REG-C | NTU side of the regenerator | +| REG-R | LTU side of the regenerator | +| SDH | Synchronous Digital Hierarchy | +| TMN | Telecommunication Management Network | +| TS | Time slot | +| TU-12 | Tributary Unit-12 | +| UI | Unit Interval | +| UNI | User Network Interface | +| UTC | Unable to comply | +| VC-12 | Virtual Container-12 | + +# 4 Reference configuration and functional description + +An access digital section which uses HDSL technology can be considered as a number of functional blocks, see Figure 1. Depending upon the HDSL transceiver (H) transmission rate, a fully equipped HDSL core consists of one 2320 kbit/s, two 1168 kbit/s, or two or three 784 kbit/s HDSL transceiver pairs connected by Digital Local Lines (DLLs) [which are linked by some common circuitry (C)]. The HDSL core is application independent. Operation with a non-fully equipped HDSL core is also permitted. + +If enhanced transmission range is required the HDSL core may contain optional regenerators (REGs). The overall insertion loss of the HDSL core with regenerator shall be less than 1.8 times the value Y of the non-regenerated HDSL core. The regenerator may be inserted at any convenient intermediate point in the HDSL core with the limitation that the insertion loss of each part-DLL shall be less than 0.9 times Y. In addition there may be further restrictions in line length due to power feeding. + +An application is defined by the interface (I) and mapping and maintenance (M) functionalities. + +The functionalities at the exchange side constitute the Line Termination Unit (LTU) and act as master to the (slave) customer side functionalities, which collectively form the Network Termination Unit (NTU) and the REGs where applicable. + +![Diagram of an access digital section employing HDSL technology. It shows a Customer side connected to an NTU (Network Termination Unit), which is connected to an HDSL Core containing DLL, REG, and H blocks, which is then connected to an LTU (Line Termination Unit) and finally to an Application interface. The diagram is labeled with functional blocks like I (Interface), M (Mapping), C (Common circuitry), H (HDSL transceiver), DLL (Digital Local Line), and REG (Regenerator).](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg) + +The diagram illustrates the functional architecture of an HDSL access digital section. At the far left, the 'Customer side' connects to the 'NTU (Network Termination Unit)'. The NTU contains functional blocks 'I' (Interface), 'M' (Mapping), and 'C' (Common circuitry). It connects to the 'HDSL Core', which includes 'H' (HDSL transceiver), 'DLL' (Digital Local Line), and 'REG' (Regenerator) blocks. The HDSL Core connects to the 'LTU (Line Termination Unit)', which also contains 'C', 'H', 'M', and 'I' blocks. The LTU connects to the 'Application interface' at the far right. The entire assembly is labeled as the 'Access digital section' at the top. A 'Note' is present below the HDSL Core section. The diagram is identified by the code 'T1528820-98' in the bottom right corner. + +Diagram of an access digital section employing HDSL technology. It shows a Customer side connected to an NTU (Network Termination Unit), which is connected to an HDSL Core containing DLL, REG, and H blocks, which is then connected to an LTU (Line Termination Unit) and finally to an Application interface. The diagram is labeled with functional blocks like I (Interface), M (Mapping), C (Common circuitry), H (HDSL transceiver), DLL (Digital Local Line), and REG (Regenerator). + +Description of functional blocks: + +- C Common circuitry +- H HDSL transceiver +- I Interface +- M Mapping +- REG Regenerator +- DLL Digital Local Line + +NOTE – A fully equipped HDSL core consists of one, two or three H, REG and DLL combinations depending on HDSL transceiver data transmission rate. REGs are optional. + +**Figure 1/G.991.1 – Access digital section employing HDSL technology (simplified configuration)** + +It should be noted that throughout this Recommendation, reference is made to the terms REG-C, REG-R and individual HDSL transmission systems. REG-R identifies functionalities located at the LTU side of the regenerator, REG-C identifies functionalities located at the NTU side of the regenerator. + +Figure 2 describes the maintenance and other communication functionalities more clearly. + +![Figure 2/G.991.1 – Access digital section employing HDSL technology (detailed configuration). The diagram shows the flow of data from an application interface through mapping and maintenance functions, into a 144-byte core frame, then through common circuitry and an HDSL transceiver to a Network Terminal Unit (NTU). The NTU connects to Digital Local Lines (DLLs). On the other side, an HDSL transceiver connects to a Line Terminal Unit (LTU), which then connects through common circuitry and an HDSL transceiver to another mapping and maintenance function, which finally connects to an application interface on the network side. The HDSL core is transparent to the core frame payload. Maintenance channels are shown between the mapping and common circuitry blocks. REG (Regenerator) blocks are shown as optional components in the HDSL core. The diagram is labeled with 'Access digital section', 'HDSL core', 'Application interface', 'Clock and synchronization information', 'transparent to core frame payload', 'Interface', 'Mapping', 'Maintenance', 'Common circuitry', 'HDSL transceiver', 'REG', 'NTU', 'LTU', 'Digital Local Lines (DLLs)', 'Network side', 'Maintenance (Reference Point)', '144 byte Core frame', and 'Maintenance channel'. A legend at the bottom left indicates that a solid line represents bidirectional transmission and a dashed box represents a functional block. A note at the bottom right states 'T1528830-98'.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +Figure 2/G.991.1 – Access digital section employing HDSL technology (detailed configuration). The diagram shows the flow of data from an application interface through mapping and maintenance functions, into a 144-byte core frame, then through common circuitry and an HDSL transceiver to a Network Terminal Unit (NTU). The NTU connects to Digital Local Lines (DLLs). On the other side, an HDSL transceiver connects to a Line Terminal Unit (LTU), which then connects through common circuitry and an HDSL transceiver to another mapping and maintenance function, which finally connects to an application interface on the network side. The HDSL core is transparent to the core frame payload. Maintenance channels are shown between the mapping and common circuitry blocks. REG (Regenerator) blocks are shown as optional components in the HDSL core. The diagram is labeled with 'Access digital section', 'HDSL core', 'Application interface', 'Clock and synchronization information', 'transparent to core frame payload', 'Interface', 'Mapping', 'Maintenance', 'Common circuitry', 'HDSL transceiver', 'REG', 'NTU', 'LTU', 'Digital Local Lines (DLLs)', 'Network side', 'Maintenance (Reference Point)', '144 byte Core frame', and 'Maintenance channel'. A legend at the bottom left indicates that a solid line represents bidirectional transmission and a dashed box represents a functional block. A note at the bottom right states 'T1528830-98'. + +NOTE – A fully equipped HDSL core consists of one, two or three H, REG, DLL combinations depending on HDSL transceiver data transmission rate. REGs are optional. + +**Figure 2/G.991.1 – Access digital section employing HDSL technology (detailed configuration)** + +The information transmitted between the NTU side (slave side) and LTU side (master side) is handled as follows: + +At the application interface (I), the data flow is grouped in application frames (e.g. 32 time slot ISDN primary rate frames, as specified in Recommendation I.431 [3]). + +For 2048 kbit/s applications the mapping function (part of the M functional block) then takes the application frame and inserts it into a 144 byte core frame. (In some applications not all data bytes will contain valid information and may be set to idle patterns.) For 1544 kbit/s applications only the framing bit is provided twice. + +The core frame is then given to the common circuitry (C) where it is combined with any necessary alignment bits, maintenance bits and overhead bits, in order to be sent transparently in HDSL frames over the DLLs. The use of REGs is optional. + +At the receiving side, data within the HDSL frames is multiplexed by the common circuitry to again form the core frame, which is passed to the mapping function where it is mapped into the application frame and transmitted over the application interface (I). + +An overview of the different framing procedures can be found in Figure 3. + +![Figure 3/G.991.1 – An overview of framing procedures. The diagram shows the flow of data from an application interface through various functional blocks including Mapping, Maintenance, Common circuitry, and HDSL transceiver to produce an HDSL frame for pair 1. It also shows the return path for Clock and Synchronization information. A legend defines bidirectional transmission and functional blocks. A note explains that in a fully equipped HDSL core with n pairs, each HDSL frame contains 1/n core frame payload plus frame alignment and maintenance bits.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Application interface + +Clock and Synchronization information + +HDSL core + +pair 1 + +Interface + +Mapping + +Maintenance + +Common circuitry + +Maintenance + +HDSL transceiver + +Maintenance (Reference point) + +Maintenance channel + +Maintenance (Reference point) + +(Note) + +Application frame + +Core frame + +144 byte payload + +HDSL frame (pair 1) + +T1528840-98 + +— Bidirectional transmission + +□ Functional block + +In a HDSL core fully equipped with n pairs, each HDSL frame contains: +1/n core frame payload plus frame alignment and maintenance bits. + +Figure 3/G.991.1 – An overview of framing procedures. The diagram shows the flow of data from an application interface through various functional blocks including Mapping, Maintenance, Common circuitry, and HDSL transceiver to produce an HDSL frame for pair 1. It also shows the return path for Clock and Synchronization information. A legend defines bidirectional transmission and functional blocks. A note explains that in a fully equipped HDSL core with n pairs, each HDSL frame contains 1/n core frame payload plus frame alignment and maintenance bits. + +NOTE – A fully equipped HDSL core consists of one, two or three H, REG, DLL combinations depending on HDSL transceiver data transmission rate. REGs are optional. + +**Figure 3/G.991.1 – An overview of framing procedures** + +In addition, there may be maintenance and/or power feeding functions associated with the HDSL core for the support of failure identification, localization and HDSL start-up control, however the presentation of this information at the maintenance reference point is outside the scope of this Recommendation. + +The specification of the HDSL core is aimed at interoperability of two equipments from different vendors. + +# 5 HDSL core specification + +## 5.1 Functions + +The functions listed below are necessary for the correct operation of the HDSL core. + +| Functions related to the HDSL core | LTU | NTU/REG | +|-------------------------------------------------------------------------------|-----|---------| +| Transparent transport of core frames (144 bytes for 2048 kbit/s applications) | | ↔ | +| Stuffing and destuffing | | ↔ | +| CRC-6 procedures and transmission error detection | | ↔ | +| Error reporting | | ↔ | +| Failure detection | | ↔ | +| Failure reporting | | ↔ | +| Bit timing | | ↔ | +| Frame alignment | | ↔ | +| HDSL transceiver autonomous start-up control | | → | +| Loopback control and coordination | | → | +| Mapping of core frames into HDSL frames | | ↔ | + +| Functions related to the HDSL core | LTU | NTU/REG | +|-----------------------------------------------------------------------|------------|----------------| +| Control of maintenance channel | | ↔ | +| Synchronization and coordination of HDSL transceivers | | → | +| Identification of pairs (available only for 2048 kbit/s applications) | | ↔ | +| Correction of pair identification | | Note | +| NOTE – Correction of pairs is a function of the NTU. | | | +| Functions related to power feeding | LTU | NTU/REG | +| Remote power feeding (optional) | | → | +| Wetting current (optional) | | → | + +### **5.1.1 Transparent transport of core frames** + +This function provides for the bidirectional transmission of the core frames (e.g. with 144 bytes for 2048 kbit/s applications) over one, two or three parallel HDSL transceiver systems connected by separate pairs. + +### **5.1.2 Stuffing and destuffing** + +This function provides for the synchronization of the application data clock to the HDSL transceiver system clock, by means of adding zero or two stuffing quats per HDSL frame. + +### **5.1.3 CRC-6 procedures and transmission error detection** + +This function provides for error performance monitoring of the HDSL transceiver systems in each HDSL frame. + +### **5.1.4 Error reporting** + +This function provides for the reporting of errors detected by means of CRC-6 procedure. + +### **5.1.5 Failure detection** + +This function provides for the detection of failures in the HDSL transceiver system. + +### **5.1.6 Failure reporting** + +This function provides for the reporting of failures detected in the HDSL transceiver systems by means of messages in the maintenance channel realised, i.e. by HDSL frame overhead bits. + +### **5.1.7 Bit timing** + +This function provides bit (signal element) timing to enable the HDSL transceiver systems to recover information from the aggregate bit stream. + +### **5.1.8 Frame alignment** + +This function provides information to enable the HDSL transceiver systems to recover the HDSL frame and the HDSL frame overhead. + +### **5.1.9 HDSL transceiver autonomous start-up control** + +This function provides for the recovering of the operational state after first powering or breakdown of the HDSL transceiver systems. + +### **5.1.10 Loopback control and coordination** + +This function provides for the activation and release of loopbacks in the LTU, the REG and the NTU. + +### **5.1.11 Mapping between core frames and HDSL frames** + +This function provides for the mapping between the core frame (e.g. with 144 bytes for 2048 kbit/s applications) and the HDSL frame(s). + +### **5.1.12 Control of the maintenance channel** + +This function provides for the control of the maintenance channel formed by the HDSL frame overhead bits. + +### **5.1.13 Synchronization and coordination of HDSL transceivers** + +This function provides for the synchronization of the HDSL transceiver systems, the equalization of different signal delays on the pairs and the correct sequence of the signals coming from the separate pairs. + +### **5.1.14 Identification of pairs** + +This function provides for the marking of the pairs at the LTU/NTU (e.g. for 2048 kbit/s applications using 2B1Q or CAP line code) by means of two or three Z bits per pair to enable the correct identification of the pairs. + +### **5.1.15 Correction of pair identification** + +This function provides for the realignment of the identification of pairs if an unintentional interchange of pairs has occurred and was detected by the NTU. + +### **5.1.16 Remote power feeding** + +This optional function provides for remote power feeding of either the NTU – if no REG is provided – or the REG from the LTU via the pairs. + +### **5.1.17 Wetting current** + +This optional function provides for feeding of a low current on the pairs to mitigate the effect of corrosion of contacts. + +## **5.2 Transmission medium** + +### **5.2.1 Description** + +The transmission medium over which the digital transmission system is expected to operate is the local line distribution network. + +A local line distribution network employs cables of pairs to provide services to customers. + +In a local line distribution network, customers are connected to the local exchange via local lines. + +A metallic local line is able to simultaneously carry bidirectional digital information in the appropriate HDSL format. + +To simplify the provision of HDSL, a digital transmission system must be capable of satisfactory operation over the majority of metallic local lines without requirement of any special conditioning. In order to permit the use of HDSL transmission systems on the maximum possible number of local + +lines, the restrictions imposed by HDSL requirements are kept to the minimum necessary to guarantee acceptable operation. + +### 5.2.2 Minimum Digital Local Line (DLL) requirements for HDSL applications + +- no loading coils; +- only twisted pair or quad cable; +- no additional shielding necessary; +- when bridged taps are present, the maximum number shall be limited to 2 and the length of each to 500 m. + +### 5.2.3 DLL physical characteristics + +A DLL is constructed of one or more cable sections that are spliced or interconnected together. + +The distribution or main cable is structured as follows: + +- cascade of cable sections of different diameters and lengths; +- up to two bridged taps (BTs) may exist at various points in installation and distribution cables. + +A general description of the DLL physical model is shown in Figure 4 and typical examples of cable characteristics based on Recommendation G.960 [2] are given in Table 1. + +![Figure 4/G.991.1 – DLL physical model diagram showing the sequence of components: HDSL NTU, Installation cable, SDP, Distribution cable, CCP, Main cable, MDF, Exchange cable, and HDSL LTU. A legend below defines SDP as Subscriber Distribution Point, CCP as Cross Connect Point, and MDF as Main Distribution Frame. A code T1528850-98 is also present.](40f30e4d577a17052f8b1e6dc802a0d8_img.jpg) + +``` + +graph LR + NTU[HDSL NTU] -- "Installation cable" --> SDP[SDP] + SDP -- "Distribution cable" --> CCP[CCP] + CCP -- "Main cable" --> MDF[MDF] + MDF -- "Exchange cable" --> LTU[HDSL LTU] + +``` + +SDP Subscriber Distribution Point + CCP Cross Connect Point + MDF Main Distribution Frame + +T1528850-98 + +Figure 4/G.991.1 – DLL physical model diagram showing the sequence of components: HDSL NTU, Installation cable, SDP, Distribution cable, CCP, Main cable, MDF, Exchange cable, and HDSL LTU. A legend below defines SDP as Subscriber Distribution Point, CCP as Cross Connect Point, and MDF as Main Distribution Frame. A code T1528850-98 is also present. + +**Figure 4/G.991.1 – DLL physical model** + +**Table 1/G.991.1 – Cable characteristics** + +| | Exchange cable | Main cable | Distribution cable | Installation cable | +|-------------------------|---------------------|---------------------------------|--------------------------|--------------------------------------| +| Wire diameter (mm) | 0.5; 0.6; 0.32; 0.4 | 0.3-1.4 | 0.3-1.4 | 0.4; 0.5;
0.6; 0.8;
0.9; 0.63 | +| Structure | SQ (B) or TP (L) | SQ (B) or TP (L) | SQ (B) or TP (L) | SQ or TP or UP | +| Maximum number of pairs | 1200 | 2400 (0.4 mm)
4800 (0.32 mm) | 600 (0.4 mm) | 2 (aerial)
600 (in house) | +| Installation | | underground
in ducts | underground
or aerial | aerial (drop)
in ducts (in house) | + +**Table 1/G.991.1 – Cable characteristics (concluded)** + +| | Exchange cable | Main cable | Distribution cable | Installation cable | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------|----------------|--------------------|--------------------| +| Capacitance (nF/km at 800 Hz) | 55 ... 120 | 25 ... 60 | 25 ... 60 | 35 ... 120 | +| Wire insulation | PVC, FRPE | PE, paper pulp | paper, PE, Cell PE | PE, PVC | +| TP | Twisted Pairs | | | | +| SQ | Star Quads | | | | +| UP | Untwisted Pairs | | | | +| L | Layer | | | | +| B | Bundles (units) | | | | +| | PE Polyethylene
PVC Polyvinylchloride
Pulp Pulp of paper
Cell PE Cellular Foam Polyethylene
FRPE Fire Resistant PE | | | | +| NOTE – This table is intended to describe the cables presently installed in the local loop. Not all of the above cable types are suitable for HDSL systems. | | | | | + +### 5.2.4 DLL electrical characteristics + +The transmitted signal will suffer from impairments due to crosstalk, impulsive noise and the non-linear variation with frequency of DLL characteristics. These impairments are described in more detail in the following subclauses. + +#### 5.2.4.1 Principal characteristics + +The principal electrical characteristics varying nonlinearly with frequency are: + +- insertion loss; +- group delay; +- characteristic impedance, comprising real and imaginary parts. + +The maximum value for insertion loss specified for HDSL transmission systems is defined in clause 6, for the one, two- and three-pair systems. + +NOTE – The term group delay is defined in Fascicle I.3 [4]. + +#### 5.2.4.2 Differences in physical transmission characteristics between pairs in the DLL + +Between the LTU and NTU the characteristics of the pairs may differ. This difference may be in wire diameter, insulation type, length, number and length of bridged taps and exposure to impairments. These differences in transmission characteristics may change with time. + +The common circuitry shall compensate for any differences in the transmission time due to these pair differences. (See clause 6). + +It is recommended that the difference of signal transfer delay between each of the two or three-pairs is limited to a maximum of 50 µs at 150 kHz, corresponding to about 10 km difference in line length between LTU and NTU. + +#### 5.2.4.3 Crosstalk characteristics + +Crosstalk noise in general results due to finite coupling loss between pairs sharing the same cable, especially those pairs that are physically adjacent. Finite coupling loss between pairs causes a vestige of the signal flowing on one DLL (disturber DLL) to be coupled into an adjacent DLL (disturbed DLL). This vestige is known as crosstalk noise. + +Near-end crosstalk (NEXT) is assumed to be the dominant type of crosstalk. + +Intersystem NEXT results when pairs carrying different digital transmission systems interfere with each other. + +Intrasystem NEXT or self-NEXT results when all pairs interfering with each other in a cable are carrying the same digital transmission system. Intrasystem NEXT noise coupled into a disturbed DLL from a number of DLL disturbers can be represented as being due to an equivalent single disturber DLL with a coupling loss versus frequency characteristics known as Power Sum Loss (PSL). Values for 1% worst case NEXT loss vary from 40 dB to 70 dB at 150 kHz depending upon the cable type, number of disturbers and environment. + +For testing HDSL systems the NEXT is represented by an artificial noise as defined in clause 6. + +#### **5.2.4.4 Unbalance about earth** + +The DLL will have finite balance about earth. Unbalance about earth is described in terms of Longitudinal Conversion Loss (LCL). The expected worst case value is 42.5 dB at 150 kHz decreasing with frequency by 5 dB/decade. + +#### **5.2.4.5 Impulse noise** + +The DLL will have impulse noise resulting from other systems sharing the same cables as well as from other sources. The requirement for tolerance to impulse noise is described in detail in clause 6. + +#### **5.2.4.6 Micro interruptions** + +A micro interruption is a temporary line interruption due to external mechanical action on the copper wires constituting the transmission path, for example, at a cable splice. Splices can be hand-made wire-to-wire junctions, and during cable life oxidation phenomena and mechanical vibrations can induce micro interruptions at these critical points. + +The effect of a micro interruption on the transmission system can be a failure of the digital transmission link, together with a failure of the power feeding (if provided) for the duration of the micro interruption. + +The objective is, that in the presence of a micro interruption of specified maximum length the system should not reset, and the system should automatically reactivate with a complete start-up procedure if a reset occurs due to an interruption. The requirements for tolerance to micro interruptions, together with guidelines for a laboratory susceptibility test set are given in clause 6. + +## **5.3 Transmission method** + +### **5.3.1 General** + +The transmission system provides for duplex transmission on 2-wire metallic local lines. Duplex transmission shall be achieved through the use of an Echo Cancellation Hybrid (ECH). With the echo cancellation method, illustrated in Figure 5, the Echo Canceller (EC) produces a replica of the echo of the transmitted signal that is subtracted from the total received signal. The echo is the result of imperfect balance of the hybrid and impedance discontinuities, caused e.g. by splicing different kind of cables. + +![Functional diagram of the echo cancellation method showing two HDSL Transceivers (NTU and LTU) connected by a line. Each transceiver contains a Transmitter (TX), a Receiver (RCV), an Echo Canceller (EC), and a Hybrid (HB). The diagram illustrates the signal flow and echo cancellation process within each transceiver.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +The diagram shows two HDSL Transceivers, one on the left labeled 'HDSL Transceiver of the NTU' and one on the right labeled 'HDSL Transceiver of the LTU', connected by a central line. Each transceiver is enclosed in a dashed box and contains four main components: a Transmitter (TX), a Receiver (RCV), an Echo Canceller (EC), and a Hybrid (HB). In the NTU transceiver, the TX output connects to a Hybrid (HB). The HB has two outputs: one connected to the external line and another connected to the EC. The EC also has two outputs: one connected to the external line and another connected to the RCV. The RCV output is connected to the external line. The same configuration is shown for the LTU transceiver, but the components are mirrored. A legend below the diagram defines the components: TX Transmitter, RCV Receiver, EC Echo Canceller, and HB Hybrid. A reference code 'T1528860-98' is located in the bottom right corner of the diagram area. + +Functional diagram of the echo cancellation method showing two HDSL Transceivers (NTU and LTU) connected by a line. Each transceiver contains a Transmitter (TX), a Receiver (RCV), an Echo Canceller (EC), and a Hybrid (HB). The diagram illustrates the signal flow and echo cancellation process within each transceiver. + +**Figure 5/G.991.1 – Functional diagram of the echo cancellation method** + +### 5.3.2 Transmission on three-pairs + +Transmission on three DLLs is provided by three parallel HDSL transceivers, each operating at 784 kbit/s and using 2B1Q line code. + +### 5.3.3 Transmission on two-pairs + +Transmission on two DLLs is provided by two parallel HDSL transceivers, each operating at 1168 kbit/s using 2B1Q or CAP line code for 2048 kbit/s applications or 784 kbit/s using 2B1Q line code for 1544 kbit/s applications. + +### 5.3.4 Transmission on one-pair + +Transmission on one DLL is provided by one HDSL transceiver operating at 2320 kbit/s and using 2B1Q or CAP line code. + +### 5.3.5 Transmission on four-pairs + +The transmission of the complete core frame on four-pairs is not excluded, but is not at present treated here. + +### 5.3.6 Line code + +The line code described in the main part of this Recommendation is 2B1Q (two binary, one quaternary). A detailed description of CAP is given in Annex B. + +Before transmission the bit stream in each HDSL transceiver of Figure 1, except the synchronization word which has a fixed pattern, shall be grouped into pairs of bits which are converted to quaternary symbols (quats) as specified in Table 2. At the receiver, the inverse operations are performed. + +**Table 2/G.991.1 – 2B1Q coding** + +| First bit
(Sign) | Second bit
(Magnitude) | Quaternary
Symbol | +|---------------------|---------------------------|----------------------| +| 1 | 0 | +3 | +| 1 | 1 | +1 | +| 0 | 1 | -1 | +| 0 | 0 | -3 | + +### 5.3.7 Line symbol rate + +The symbol rate of the HDSL transceiver shall be: + +- 392 kbaud $\pm$ 32 ppm for a three-pair system; +- 584 kbaud $\pm$ 32 ppm for a two-pair system; and +- 1160 kbaud $\pm$ 32 ppm for a one-pair system. + +## 5.4 Frame structure + +### 5.4.1 Core frame + +Inside the mapping functional block, as indicated in the reference configuration in Figure 3, the application dependent frame containing the payload is inserted into a 500 $\mu$ s long core frame containing 144 bytes as shown in Figure 6. Different mapping options depending on the special applications exist, as shown in Figure 6. The details of mapping procedures for different applications are described in Appendix I. The core frames with 144 bytes/500 $\mu$ s form a continuous bit stream with a bit rate of 2304 kbit/s which in two- or three-pair systems are split on a byte per byte basis into parallel HDSL frames which are transmitted in each one of the HDSL transceiver systems. + +![Figure 6/G.991.1 – Core frame. A diagram showing three columns (a, b, c) representing different frame structures over time (0 μs to 500 μs). Column (a) shows the core frame byte structure. Column (b) shows the asynchronous mapping structure with R, Y, and 32-byte payload blocks. Column (c) shows the synchronous mapping structure with Byte 1 at the top and Byte 144 at the bottom, with a note in between.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg) + +0 μs + +| | +|---------------| +| Byte 1 | +| Byte 2 | +| Bytes 3-35 | +| Byte 36 | +| Byte 37 | +| Bytes 38-71 | +| Byte 72 | +| Bytes 73-107 | +| Byte 108 | +| Bytes 109-143 | +| Byte 144 | + +500 μs + +**a) Byte # of core frame** + +| | +|----------| +| R | +| R | +| 32 bytes | +| R | +| Y | +| R | +| R | +| 32 bytes | +| R | +| Y | +| R | +| R | +| 32 bytes | +| R | +| Y | + +**b) Asynchronous mapping** + +| | +|----------| +| Byte 1 | +| (Note) | +| Byte 144 | + +**c) Synchronous mapping** + +T1528870-98 + +Figure 6/G.991.1 – Core frame. A diagram showing three columns (a, b, c) representing different frame structures over time (0 μs to 500 μs). Column (a) shows the core frame byte structure. Column (b) shows the asynchronous mapping structure with R, Y, and 32-byte payload blocks. Column (c) shows the synchronous mapping structure with Byte 1 at the top and Byte 144 at the bottom, with a note in between. + +R, Y Fixed Stuffing + +NOTE – The core frame and the payload are synchronized. The details of the application dependent time slot allocation are given in the relevant subclauses of clause 7. + +**Figure 6/G.991.1 – Core frame** + +### 5.4.2 2B1Q HDSL frame + +This subclause describes the proposed HDSL frame structure in the binary format before scrambling and encoding. This structure is valid during normal operation after symbol timing synchronization, frame alignment and after all internal transceiver coefficients have been stabilized sufficiently to permit a reliable transport of the signals through the HDSL transceiver systems. + +- The nominal HDSL frame length is 6 ms. +- The mean length of the HDSL frame for the three-pair system is 2352 quats (equivalent to 4704 bits) in 6 ms. Each individual frame contains either 0 or 2 stuffing quats which gives a real length of 2351 quats in $6 - \frac{1}{392}$ ms or 2353 quats in $6 + \frac{1}{392}$ ms. + +- The mean length of the HDSL frame for the two-pair system is 3504 quats (equivalent to 7008 bits) in 6 ms. Each individual frame contains either 0 or 2 stuffing quats which gives a real length of 3503 quats in $6 - \frac{1}{584}$ ms or 3505 quats in $6 + \frac{1}{584}$ ms. +- The mean length of the HDSL frame for the one-pair system is 6960 quats (equivalent to 13 920 bits) in 6 ms. Each individual frame contains either 0 or 2 stuffing quats which gives a real length of 6959 quats in $6 - \frac{1}{1160}$ ms or 6961 quats in $6 + \frac{1}{1160}$ ms. +- The bit assignment in each HDSL frame in each direction of transmission for all pairs is shown in Tables 3, 4 and 5. +- The HDSL transceiver systems shall each independently accommodate differences in the bit timing of the two directions of transmission or of the application data and the HDSL transceiver system by including none or two stuffing quats at the end of the HDSL frame. +- In the LTU the frame rate on the different pairs shall be derived from the same source. The location of the synchronization word, i.e. the start of the HDSL frames in the different pairs shall be synchronized to each other. The maximum delay between the start of the frames shall be less than one symbol period, measured at the line side of each HDSL transceiver. +- The insertion of stuffing quats, if necessary shall be identical for all pairs. + +**Table 3/G.991.1 – HDSL frame structure for the three-pair system** + +| Time | Frame Bit # | HOH Bit # | Abbr. name | Full name | Notes | +|------|-------------|-----------|------------|-----------------------------------------------------------|------------------------------------------| +| 0 ms | 1-14 | 1-14 | SW 1-14 | Sync word | Double Barker Code | +| | 15 | 15 | losd | loss of input signal at the far end application interface | | +| | 16 | 16 | febe | far end block error | | +| | 17-1180 | – | B01-B12 | payload block 1-12 | HDSL payload including $Z_{m1}-Z_{m12}$ | +| | 1181 | 17 | eoc01 | eoc address | | +| | 1182 | 18 | eoc02 | eoc address | | +| | 1183 | 19 | eoc03 | eoc data/opcode | | +| | 1184 | 20 | eoc04 | eoc odd/even byte | | +| | 1185 | 21 | crc1 | cyclic redundancy check | CRC-6 | +| | 1186 | 22 | crc2 | cyclic redundancy check | CRC-6 | +| | 1187 | 23 | ps1 | NTU power status bit 1 | NTU → LTU only | +| | 1188 | 24 | ps2 | NTU power status bit 2 | NTU → LTU only | +| | 1189 | 25 | bpv | bipolar violation | | +| | 1190 | 26 | eoc05 | eoc unspecified | | +| | 1191-2354 | – | B13-B24 | Payload blocks 13-24 | HDSL payload including $Z_{m13}-Z_{m24}$ | +| | 2355 | 27 | eoc06 | eoc-message bit 1 | | +| | 2356 | 28 | eoc07 | eoc-message bit 2 | | +| | 2357 | 29 | eoc08 | eoc-message bit 3 | | + +**Table 3/G.991.1 – HDSL frame structure for the three-pair system (concluded)** + +| Time | Frame Bit # | HOH Bit # | Abrv. name | Full name | Notes | +|------------------------|-------------|-----------|------------|---------------------------------|----------------------------------------------| +| | 2358 | 30 | eoc09 | eoc-message bit 4 | | +| | 2359 | 31 | crc3 | cyclic redundancy check | CRC-6 | +| | 2360 | 32 | crc4 | cyclic redundancy check | CRC-6 | +| | 2361 | 33 | hrp | regenerator present | LTU ← REG → NTU | +| | 2362 | 34 | rrbe | regenerator remote block error | LTU ← REG → NTU | +| | 2363 | 35 | rcbe | regenerator central block error | LTU ← REG → NTU | +| | 2364 | 36 | rega | regenerator alarm | LTU ← REG → NTU | +| | 2365-3528 | – | B25-B36 | payload blocks 25-36 | HDSL payload including $Z_{m25}$ - $Z_{m36}$ | +| | 3529 | 37 | eoc10 | eoc-message bit 5 | | +| | 3530 | 38 | eoc11 | eoc-message bit 6 | | +| | 3531 | 39 | eoc12 | eoc-message bit 7 | | +| | 3532 | 40 | eoc13 | eoc-message bit 8 | | +| | 3533 | 41 | crc5 | cyclic redundancy check | CRC-6 | +| | 3534 | 42 | crc6 | cyclic redundancy check | CRC-6 | +| | 3535 | 43 | rta | remote terminal alarm | NTU → LTU only | +| | 3536 | 44 | indc/indr | ready to receive | indc = LTU → NTU
indr = NTU → LTU | +| | 3537 | 45 | uib | unspecified indicator bit | | +| | 3538 | 46 | uib | unspecified indicator bit | | +| $6 - \frac{1}{392}$ ms | 3539-4702 | – | B37-B48 | payload blocks 37-48 | HDSL Payload including $Z_{m37}$ - $Z_{m48}$ | +| | 4703 | 47 | stq1s | stuff quat 1 sign | Frame stuffing | +| 6 ms nominal | 4704 | 48 | stq1m | stuff quat 1 magnitude | Frame stuffing | +| | 4705 | 49 | stq2s | stuff quat 2 sign | Frame stuffing | +| $6 + \frac{1}{392}$ ms | 4706 | 50 | stq2m | stuff quat 2 magnitude | Frame stuffing | + +**Table 4/G.991.1 – HDSL frame structure for the two-pair system** + +| Time | Frame Bit # | HOH Bit # | Abrv. name | Full name | Notes | +|------|-------------|-----------|------------|-----------------------------------------------------------|----------------------------------------------| +| 0 ms | 1-14 | 1-14 | SW 1-14 | Sync word | Double Barker Code | +| | 15 | 15 | losd | loss of input signal at the far end application interface | | +| | 16 | 16 | febe | far end block error | | +| | 17-1756 | – | B01-B12 | payload block 1-12 | HDSL payload including $Z_{m1}$ - $Z_{m12}$ | +| | 1757 | 17 | eoc01 | eoc address | | +| | 1758 | 18 | eoc02 | eoc address | | +| | 1759 | 19 | eoc03 | eoc data/opcode | | +| | 1760 | 20 | eoc04 | eoc odd/even byte | | +| | 1761 | 21 | crc1 | cyclic redundancy check | CRC-6 | +| | 1762 | 22 | crc2 | cyclic redundancy check | CRC-6 | +| | 1763 | 23 | ps1 | NTU power status bit 1 | NTU → LTU only | +| | 1764 | 24 | ps2 | NTU power status bit 2 | NTU → LTU only | +| | 1765 | 25 | bpv | bipolar violation | | +| | 1766 | 26 | eoc05 | eoc unspecified | | +| | 1767-3506 | – | B13-B24 | payload blocks 13-24 | HDSL payload including $Z_{m13}$ - $Z_{m24}$ | +| | 3507 | 27 | eoc06 | eoc-message bit 1 | | +| | 3508 | 28 | eoc07 | eoc-message bit 2 | | +| | 3509 | 29 | eoc08 | eoc-message bit 3 | | +| | 3510 | 30 | eoc09 | eoc-message bit 4 | | +| | 3511 | 31 | crc3 | cyclic redundancy check | CRC-6 | +| | 3512 | 32 | crc4 | cyclic redundancy check | CRC-6 | +| | 3513 | 33 | hrp | regenerator present | LTU ← REG → NTU | +| | 3514 | 34 | rrbe | regenerator remote block error | LTU ← REG → NTU | +| | 3515 | 35 | rcbe | regenerator central block error | LTU ← REG → NTU | +| | 3516 | 36 | rega | regenerator alarm | LTU ← REG → NTU | +| | 3517-5256 | – | B25-B36 | payload blocks 25-36 | HDSL payload including $Z_{m25}$ - $Z_{m36}$ | +| | 5257 | 37 | eoc10 | eoc-message bit 5 | | +| | 5258 | 38 | eoc11 | eoc-message bit 6 | | +| | 5259 | 39 | eoc12 | eoc-message bit 7 | | +| | 5260 | 40 | eoc13 | eoc-message bit 8 | | + +**Table 4/G.991.1 – HDSL frame structure for the two-pair system (concluded)** + +| Time | Frame Bit # | HOH Bit # | Abrv. name | Full name | Notes | +|------------------------|-------------|-----------|------------|---------------------------|------------------------------------------| +| | 5261 | 41 | crc5 | cyclic redundancy check | CRC-6 | +| | 5262 | 42 | crc6 | cyclic redundancy check | CRC-6 | +| | 5263 | 43 | rta | remote terminal alarm | NTU → LTU only | +| | 5264 | 44 | indc/indr | ready to receive | indc = LTU → NTU
indr = NTU → LTU | +| | 5265 | 45 | uib | unspecified indicator bit | | +| | 5266 | 46 | uib | unspecified indicator bit | | +| $6 - \frac{1}{584}$ ms | 5267-7006 | – | B37-B48 | payload blocks 37-48 | HDSL payload including $Z_{m37}-Z_{m48}$ | +| | 7007 | 47 | stq1s | stuff quat 1 sign | Frame stuffing | +| 6 ms nominal | 7008 | 48 | stq1m | stuff quat 1 magnitude | Frame stuffing | +| | 7009 | 49 | stq2s | stuff quat 2 sign | Frame stuffing | +| $6 + \frac{1}{584}$ ms | 7010 | 50 | stq2m | stuff quat 2 magnitude | Frame stuffing | + +**Table 5/G.991.1 – HDSL frame structure for the one-pair system** + +| Time | Frame Bit # | HOH Bit # | Abr. name | Full name | Notes | +|------|-------------|-----------|-----------|-----------------------------------------------------------|----------------------------------------| +| 0 ms | 1-14 | 1-14 | SW 1-14 | Sync word | | +| | 15 | 15 | losd | loss of input signal at the far end application interface | | +| | 16 | 16 | febe | far end block error | | +| | 17-3484 | – | B01-B12 | payload blocks 1-12 | HDSL payload including $Z_1-Z_{12}$ | +| | 3485 | 17 | eoc01 | eoc address | | +| | 3486 | 18 | eoc02 | eoc address | | +| | 3487 | 19 | eoc03 | eoc data/opcode | | +| | 3488 | 20 | eoc04 | eoc odd/even Byte | | +| | 3489 | 21 | crc1 | cyclic redundancy check | CRC-6 | +| | 3490 | 22 | crc2 | cyclic redundancy check | CRC-6 | +| | 3491 | 23 | ps1 | NTU power status bit 1 | NTU → LTU only | +| | 3492 | 24 | ps2 | NTU power status bit 1 | NTU → LTU only | +| | 3493 | 25 | bpv | bipolar violation | | +| | 3494 | 26 | eoc05 | eoc unspecified | | +| | 3495-6962 | – | B13-B24 | payload blocks 13-24 | HDSL payload including $Z_{13}-Z_{24}$ | + +**Table 5/G.991.1 – HDSL frame structure for the one-pair system (concluded)** + +| Time | Frame Bit # | HOH Bit # | Abr. name | Full name | Notes | +|-------------------------|---------------|-----------|-----------|---------------------------------|--------------------------------------| +| | 6963 | 27 | eoc06 | eoc-message bit 1 | | +| | 6964 | 28 | eoc07 | eoc-message bit 2 | | +| | 6965 | 29 | eoc08 | eoc-message bit 3 | | +| | 6966 | 30 | eoc09 | eoc-message bit 4 | | +| | 6967 | 31 | crc3 | cyclic redundancy check | CRC-6 | +| | 6968 | 32 | crc4 | cyclic redundancy check | CRC-6 | +| | 6969 | 33 | hrp | regenerator present | LTU ← REG → NTU | +| | 6970 | 34 | rrbe | regenerator remote block error | LTU ← REG → NTU | +| | 6971 | 35 | rcbe | regenerator central block error | LTU ← REG → NTU | +| | 6972 | 36 | rega | regenerator alarm | LTU ← REG → NTU | +| | 6973-10 440 | – | B25-B36 | payload blocks 25-36 | HDSL payload including Z25-Z36 | +| | 10 441 | 37 | eoc10 | eoc-message bit 5 | | +| | 10 442 | 38 | eoc11 | eoc-message bit 6 | | +| | 10 443 | 39 | eoc12 | eoc-message bit 7 | | +| | 10 444 | 40 | eoc13 | eoc-message bit 8 | | +| | 10 445 | 41 | crc5 | cyclic redundancy check | CRC-6 | +| | 10 446 | 42 | crc6 | cyclic redundancy check | CRC-6 | +| | 10 447 | 43 | rta | remote terminal alarm | NTU → LTU only | +| | 10 448 | 44 | indc/indr | ready to receive | indc = LTU → NTU
indr = NTU → LTU | +| | 10 449 | 45 | uib | unspecified indicator bit | | +| | 10 450 | 46 | uib | unspecified indicator bit | | +| $6 - \frac{1}{1160}$ ms | 10 451-13 918 | – | B37-B48 | payload blocks 37-48 | HDSL payload including Z37-Z48 | +| | 13 919 | 47 | stq1s | stuff quat 1 sign | Frame stuffing | +| 6 ms nominal | 13 920 | 48 | stq1m | stuff quat 1 magnitude | Frame stuffing | +| | 13 921 | 49 | stq2s | stuff quat 2 sign | Frame stuffing | +| $6 + \frac{1}{1160}$ ms | 13 922 | 50 | stq2m | stuff quat 2 magnitude | Frame stuffing | + +#### 5.4.2.1 2B1Q HDSL frame structure + +##### 5.4.2.1.1 Frame structure of the three-pair system + +Figure 7 illustrates the HDSL frame structure composed of quaternary symbols (quats) and the mapping of the core frame bytes to it. The frame is subdivided into four groups. The first group of the frame starts with the seven symbols long synchronization word followed by one HDSL overhead quat and twelve blocks of HDSL payload, each consisting of 48.5 quats, equivalent to 97 bits, containing one overhead-bit $Z_{mn}$ and twelve bytes of the core frame. The $Z_{mn}$ -bits ( $m = 1 \dots 3$ indicates one of the three-pairs; $n = 1 \dots 48$ is the running number of the HDSL payload block in the frame) provide an additional overhead channel, for which forty eight bits per frame of each HDSL transceiver system at a capacity of 8 kbit/s are available. + +The first eight Z-bits ( $Z_{m1} \dots Z_{m8}$ ) are reserved for core applications. Bits $Z_{m1} \dots Z_{m3}$ are used for pair identification (see 6.2), whereas $Z_{m4} \dots Z_{m8}$ are reserved for future use and are presently set to ONE. + +The Z-bits No. 9 ... 48 ( $Z_{m9} \dots Z_{m48}$ ) are application dependent and are transparently transported through the HDSL core. The use of these bits shall be described in the application specific requirements. Unused bits shall be set to ONE. + +The three groups following the first group have an equal structure. Each consists of five HDSL overhead quats and twelve HDSL payload blocks as described above. So one frame contains a synchronization word, 16 HDSL overhead quats, 48 Z-bits and 576 bytes of the core frame. + +At the end of the frame the possibility of 2 stuffing quats is foreseen. These quats are used always together, this means either none or two stuffing quats are inserted, depending on the relation of the timing. The length of the HDSL frame is either 2353 quats, which equals $6 + \frac{1}{392}$ ms for the nominal HDSL clock frequency, or 2351 quats corresponding to $6 - \frac{1}{392}$ ms and the average will tend to 2352 quats or 6 ms. The receiver is able to evaluate the length of an incoming frame by detection of the sync word in the following frame and to adjust the demultiplexing of the data stream. + +![Diagram of HDSL frame structure for a three-pair system. The top part shows a sequence of quaternary symbols (q) over time, including sync words, overhead (HOH), and payload (B01-B48). The middle part shows the mapping of bytes from the core frame to the payload blocks for three pairs. Pair 1 contains bytes 1, 4, 7, ..., 34. Pair 2 contains bytes 2, 5, 8, ..., 35. Pair 3 contains bytes 3, 6, 9, ..., 36. Timing information is provided for the start and end of the payload block.](c494cd874a082a97b50b3c4d3938f467_img.jpg) + +Timing information: + +- Start of payload block: $(6 - \frac{1}{392})$ ms or $(6 + \frac{1}{392})$ ms +- End of payload block: $(6 - \frac{1}{392})$ ms or $(6 + \frac{1}{392})$ ms +- Duration of payload block: 6 ms +- Duration of 97 bits, 48 1/2 quats: $\frac{97}{784}$ ms + +Symbol sequence details: + +- 7q | 1q | 12 × 48 1/2 = 582q | 5q | 582q | 5q | 582q | 5q | 582q | 0, 2q +- Sync word (S1, S2, Q1, Q2) | HOH (H1, B0, B1) | ..... | HOH (H2, B1, B2) | ..... | HOH (H3, B2, B3) | ..... | HOH (H4, B3, B4) | ..... | HOH (H5, B4, B5) | ..... | HOH (H6, B5, B6) | ..... | HOH (H7, B6, B7) | ..... | HOH (H8, B7, B8) | ..... | Sync word (S1, S2, Q1, Q2) + +Pair 1: + +| | | | | | | +|-----------------|--------|--------|--------|-------|---------| +| Z 11 | Byte 1 | Byte 4 | Byte 7 | ..... | Byte 34 | +|-----------------|--------|--------|--------|-------|---------| + +Pair 2: + +| | | | | | | +|-----------------|--------|--------|--------|-------|---------| +| Z 21 | Byte 2 | Byte 5 | Byte 8 | ..... | Byte 35 | +|-----------------|--------|--------|--------|-------|---------| + +Pair 3: + +| | | | | | | +|-----------------|--------|--------|--------|-------|---------| +| Z 31 | Byte 3 | Byte 6 | Byte 9 | ..... | Byte 36 | +|-----------------|--------|--------|--------|-------|---------| + +Additional details for Pair 2: + +- Z21 is 1b (1 bit) +- Byte 2 is 8 bits +- 1/2q = 4 quats + +Diagram of HDSL frame structure for a three-pair system. The top part shows a sequence of quaternary symbols (q) over time, including sync words, overhead (HOH), and payload (B01-B48). The middle part shows the mapping of bytes from the core frame to the payload blocks for three pairs. Pair 1 contains bytes 1, 4, 7, ..., 34. Pair 2 contains bytes 2, 5, 8, ..., 35. Pair 3 contains bytes 3, 6, 9, ..., 36. Timing information is provided for the start and end of the payload block. + +HDSL Payload Block (48 per HDSL Frame) + +| Symbol | Name, function | +|-----------------|---------------------------------------------------| +| B01 to B48 | HDSL system payload blocks | +| Byte n | Byte n from core frame (n = 1 ... 144) | +| HOH | HDSL overhead (sw, eoc, crc, ...) | +| quat | Quaternary symbol | +| SQ1, SQ2 | Stuff quats | +| Sync word | 7-symbol Barker codes, "double Barker" → 14 bits | +| Z mn | Additional overhead bits (Z-bits) | +| m | Indicating corresponding pair (m = 1 ... 3) | +| n | Indicating number of payload block (n = 1 ... 48) | + +Figure 7/G.991.1 – Frame structure of the three-pair system + +##### 5.4.2.1.2 Frame structure of the two-pair system + +Figure 8 illustrates the HDSL frame structure composed of quaternary symbols (quats) and the mapping of the core frame bytes to it. The frame is subdivided into four groups. The first group of the frame starts with the seven symbols long synchronization word followed by one HDSL overhead quat and twelve blocks of HDSL payload, each consisting of 72.5 quats, equivalent to 145 bits, containing one overhead-bit $Z_{mn}$ and eighteen bytes of the core frame. The $Z_{mn}$ -bits ( $m = 1, 2$ indicates one of the two-pairs; $n = 1 \dots 48$ is the running number of the HDSL payload block in the frame) provide an additional overhead channel, for which forty-eight bits per frame of each HDSL transceiver system at a capacity of 8 kbit/s are available. + +The first eight Z-bits ( $Z_{m1} \dots Z_{m8}$ ) are reserved for core applications. Bits $Z_{m1}, Z_{m2}$ are used for pair identification (see 6.2), whereas $Z_{m3} \dots Z_{m8}$ are reserved for future use and are presently set to ONE. + +The Z-bits No. 9 ... 48 ( $Z_{m9} \dots Z_{m48}$ ) are application dependent and are transparently transported through the HDSL core. The use of these bits shall be described in the application specific requirements. Unused bits shall be set to ONE. + +The three groups following the first group have an equal structure. Each consists of five HDSL overhead quats and twelve HDSL payload blocks as described above. So one frame contains a synchronization word, 16 HDSL overhead quats, 48 Z-bits and 864 bytes of the core frame. + +At the end of the frame the possibility of 2 stuffing quats is foreseen. These quats are used always together; this means either none or two stuffing quats are inserted, depending on the relation of the timing. The length of the HDSL frame is either 3505 quats, which equals $6 + \frac{1}{584}$ ms for the nominal HDSL clock frequency, or 3503 quats corresponding to $6 - \frac{1}{584}$ ms and the average will tend to 3504 quats or 6 ms. The receiver is able to evaluate the length of an incoming frame by detection of the sync word in the following frame and to adjust the demultiplexing of the data stream. + +![Figure 8/G.991.1 – Frame structure of the two-pair system. The diagram shows the mapping of 144 core frame bytes into 3503 or 3505 quaternary symbols (quats) over a 6 ms period. The frame is divided into two pairs (Pair 1 and Pair 2). Each pair contains 72 1/2 quats (144 bits) of payload, plus overhead and synchronization. The synchronization word is 7 quats long. The payload is divided into 48 HDSL system payload blocks (B01 to B48). The diagram also shows the timing of the frame, with a duration of (6 - 1/584) ms or (6 + 1/584) ms. The HDSL Payload Block (48 per HDSL Frame) is shown below the frame structure, with a duration of 145 bits, 72 1/2 quats, or 145/1168 ms.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +Figure 8/G.991.1 – Frame structure of the two-pair system. The diagram shows the mapping of 144 core frame bytes into 3503 or 3505 quaternary symbols (quats) over a 6 ms period. The frame is divided into two pairs (Pair 1 and Pair 2). Each pair contains 72 1/2 quats (144 bits) of payload, plus overhead and synchronization. The synchronization word is 7 quats long. The payload is divided into 48 HDSL system payload blocks (B01 to B48). The diagram also shows the timing of the frame, with a duration of (6 - 1/584) ms or (6 + 1/584) ms. The HDSL Payload Block (48 per HDSL Frame) is shown below the frame structure, with a duration of 145 bits, 72 1/2 quats, or 145/1168 ms. + +HDSL Payload Block (48 per HDSL Frame) + +| Symbol | Name, Function | +|-----------------|---------------------------------------------------| +| B01 to B48 | HDSL system payload blocks | +| Byte n | Byte n from core frame (n = 1 ... 144) | +| HOH | HDSL overhead (sw, eoc, crc, ...) | +| quat | Quaternary symbol | +| SQ1, SQ2 | Stuff quats | +| Sync word | 7-symbol Barker codes, "double Barker" → 14 bits | +| Z mn | Additional overhead bits (Z-bits) | +| m | Indicating corresponding pair (m = 1 ... 2) | +| n | Indicating number of payload block (n = 1 ... 48) | + +**Figure 8/G.991.1 – Frame structure of the two-pair system** + +##### 5.4.2.1.3 Frame structure of the one-pair system + +Figure 9 illustrates the HDSL frame structure composed of quaternary symbols (quats) and the mapping of the core frame bytes to it. The frame is subdivided into four groups. The first group of the frame starts with the seven symbols long synchronization word followed by one HDSL overhead quat and twelve blocks of HDSL payload, each consisting of 144.5 quats, equivalent to 289 bits, containing one overhead-bit Zn and thirty-six bytes of the core frame. The Zn-bits (n = 1 ... 48 is the running number of the HDSL payload block in the frame) provide an additional overhead channel, for which forty-eight bits of the HDSL frame at a capacity of 8 kbit/s are available. + +The first eight Z-bits (Z1 ... Z8) are reserved for future core applications and presently set to ONE. + +The Z-bits No. 9 ... 48 (Z9 ... Z48) are application dependent and are transparently transported through the HDSL core. The use of these bits shall be described in the application specific requirements. Unused bits shall be set to ONE. + +The three groups following the first group have an equal structure. Each consists of five HDSL overhead quats and twelve HDSL payload blocks as described above. So one frame contains a synchronization word, 16 HDSL overhead quats, 48 Z-bits and 1728 bytes of the core frame. + +At the end of the frame the possibility of 2 stuffing quats is foreseen. These quats are used always together, this means either none or two stuffing quats are inserted, depending on the relation of the timing. The length of the HDSL frame is either 6961 quats, which equals $6 + \frac{1}{1160}$ ms for the nominal HDSL clock frequency, or 6959 quats corresponding to $6 - \frac{1}{1160}$ ms and the average will tend to 6960 quats or 6 ms. The receiver is able to evaluate the length of an incoming frame by detection of the sync word in the following frame and to adjust the demultiplexing of the data stream. + +![Diagram of the HDSL frame structure for a one-pair system. The diagram shows the sequence of symbols (quats) and bits (Z-bits, payload bytes) over time. The top part shows the quat sequence: Sync word (7q), overhead (1q, 12x144q/2 = 1734q), payload (5q, 1734q), overhead (5q, 1734q), overhead (5q, 1734q), and stuffing quats (0/2q). The bottom part shows the bit sequence: Pair 1 (Z1, Byte 2 to Byte 36), totaling 289 bits (144 1/2 quats). Timing markers indicate frame durations of (6 - 1/1160) ms or (6 + 1/1160) ms, with an average of 6 ms. The diagram is labeled T1528900-98.](cfb98c691c1af5befe32ff9442eea511_img.jpg) + +The diagram illustrates the frame structure of the one-pair system. It is divided into two main horizontal sections. The top section shows the sequence of quaternary symbols (quats). It begins with a 'Sync word' (7 quats), followed by an overhead section (1 quat, then 12 groups of 144 quats, totaling 1734 quats), a payload section (5 quats, then 1734 quats), another overhead section (5 quats, then 1734 quats), and finally stuffing quats (0 or 2 quats). The total number of quats is either 6959 or 6961. The bottom section shows the bit sequence. It starts with 'Pair 1' containing Z-bits (Z1) and payload bytes (Byte 2 to Byte 36). The total number of bits is 289, which is equivalent to 144 1/2 quats. Timing markers indicate that the frame duration is either $(6 - \frac{1}{1160})$ ms or $(6 + \frac{1}{1160})$ ms, with an average duration of 6 ms. The diagram is labeled T1528900-98. + +Diagram of the HDSL frame structure for a one-pair system. The diagram shows the sequence of symbols (quats) and bits (Z-bits, payload bytes) over time. The top part shows the quat sequence: Sync word (7q), overhead (1q, 12x144q/2 = 1734q), payload (5q, 1734q), overhead (5q, 1734q), overhead (5q, 1734q), and stuffing quats (0/2q). The bottom part shows the bit sequence: Pair 1 (Z1, Byte 2 to Byte 36), totaling 289 bits (144 1/2 quats). Timing markers indicate frame durations of (6 - 1/1160) ms or (6 + 1/1160) ms, with an average of 6 ms. The diagram is labeled T1528900-98. + +| Symbol | Name, function | +|----------------|---------------------------------------------------| +| B01 to B48 | HDSL system payload blocks | +| Byte n | Byte n from core frame (n = 1 ... 144) | +| HOH | HDSL overhead (sw, eoc, crc, ...) | +| quat | Quaternary symbol | +| SQ1, SQ2 | Stuff quats | +| Sync word | 7-symbol Barker codes, "double Barker" → 14 bits | +| Z n | Additional overhead bits (Z-bits) | +| n | Indicating number of payload block (n = 1 ... 48) | + +**Figure 9/G.991.1 – Frame structure of the one-pair system** + +#### 5.4.2.2 Frame bit assignments + +In Tables 3, 4 and 5 the bit sequence of the HDSL frame prior to scrambling at the transmit side and after descrambling at the receive side is presented. While the frame structures are identical in both directions of transmission, the functional assignments of individual bits in the direction LTU-to- + +NTU or NTU-to-LTU are different. Unused bits in either direction are set to ONE. For example the proposed NTU power status bits are defined only in the frame transmitted towards the LTU and the corresponding bit positions in the reverse direction have no assignment. The bit assignments are identical in each of the pairs. + +The following gives a short description of the currently defined overhead bits. + +##### – *Sync word* + +The synchronization words (sync words) enable the HDSL receivers to acquire quat and bit timing so that the incoming signals can be decoded into their original binary forms. The synchronization words shall be seven-quat Barker code sequences as shown in Table 6. The same sequence is used in both directions on all pairs. + +The coding in Table 6 will preserve the 2.50 V (one-pair) or 2.64 V (two and three-pair) peak symbol levels for the sync words on the line. + +**Table 6/G.991.1 – Seven-quat Barker code synchronization word sequence** + +| Quat # | sequence | +|--------|----------| +| 01 | +3 | +| 02 | +3 | +| 03 | +3 | +| 04 | -3 | +| 05 | -3 | +| 06 | +3 | +| 07 | -3 | + +##### – *losd-bit (loss of signal)* + +If there is no signal from the application interface, the losd-bit shall be set to ZERO in the next frame towards the far end. Under normal conditions, this bit shall be set to ONE. + +##### – *febe-bit (far end block error)* + +The febe-bit shall be set to ZERO in the following frame towards the far end, when the local receiver detects a CRC error in the HDSL frame. When there is no febe bit value ready (due to different frame lengths in the two directions) or no failure has been detected in the previous frame, the febe bit shall be set to ONE. + +##### – *eoc-bits (embedded operations channel)* + +13 bits (eoc01 ... eoc13) are provided as a separate maintenance channel. For a description of codes and the procedures used in this channel, see 5.5. + +##### – *crc-bits* + +The HDSL frame shall have six bits assigned to a Cyclic Redundancy Check (CRC) code on both directions for each pair. + +The CRC code block is calculated for the previous HDSL frame in the given direction except for the fourteen sync word bits, the six crc-bits and any stuff quat bits. + +The six crc-bits transmitted in the $(N+1)^{\text{th}}$ frame shall be determined as follows: + +- 1) All bits of the $N^{\text{th}}$ frame except the fourteen sync word bits, the six crc-bits and any stuffing bits, for a total of $m$ bits ( $m$ equals 4682 for the three-pair system, 6986 for the two-pair system and 13 888 for the one-pair system), are used, in order of occurrence, to + +construct a polynomial in "X" such that the bit "0" of the Nth frame is the coefficient of the term Xm-1 and bit m-1 of the Nth frame is the coefficient of the term X0. + +- 2) The polynomial is multiplied by the factor X6, and the result is divided, modulo 2, by the generator polynomial X6 ### X ### 1. The coefficients of the remainder polynomial are used, in order of occurrence, as the ordered set of check bits, crc1 through crc6, for the (N+1)th frame. The ordering is such that the coefficient of the term X5 in the remainder polynomial is check bit crc1 and the coefficient of the term X0 in the remainder polynomial is check bit crc6. +- 3) The check bits, crc1 through crc6, contained in a frame are those associated with the content of the preceding frame. When there is no immediately preceding frame, the check bits may be assigned any value. + +– *ps1-, ps2-bit (power supply bits)* + +The power supply bits ps1 and ps2 are used to indicate the status of the primary and secondary power supply in the NTU. The power status bit function definitions are shown in Table 7. + +**Table 7/G.991.1 – Coding of power status** + +| NTU power status | ps1 | ps2 | +|---------------------|-----|-----| +| All power normal | 1 | 1 | +| Secondary power out | 1 | 0 | +| Primary power out | 0 | 1 | +| Power loss | 0 | 0 | + +On loss of power at the NTU, there shall be enough power left to communicate three "Power Loss" messages towards the LTU. + +– *bpv-bit (bipolar violation)* + +Whenever during one HDSL frame period, a line coding violation is detected at the application interface, the bpv-bit is set to ZERO in the following frame towards the far end. Under normal conditions, this bit shall be set to ONE. + +– *hrp-bit (HDSL regenerator present)* + +If a regenerator is present, the hrp-bit shall be set to ZERO by the regenerator in both directions towards the NTU and the LTU. The NTU and the LTU set the hrp bit to ONE in the outgoing frames. + +– *rrbe-bit (regenerator remote block error)* + +The rrbe-bit shall be set to ZERO by the regenerator towards the LTU and NTU in the next outgoing frame, when a CRC error has been detected by the receiver located at the LTU-side in the regenerator. If no failure has been detected, this bit shall be set to ONE. + +– *rcbe-bit (regenerator central block error)* + +The rcbe-bit shall be set to ZERO by the regenerator towards the LTU and NTU in the next outgoing frame, when a CRC error has been detected by the receiver located at the NTU-side in the regenerator. If no failure has been detected, this bit shall be set to ONE. + +– *rta-bit (remote terminal alarm)* + +The rta-bit is set to ZERO by the NTU to signal internal alarm conditions to the LTU. The LTU, after detecting the rta-bit, may read the status register of the NTU and evaluate the reason for the failure condition. With no alarm pending in the NTU, the rta-bit is set to ONE. + +- *rega-bit (internal alarm in the regenerator)* + +The rega-bit is set by the REG to signal internal alarm conditions. The LTU, after detecting the rega-bit, may read the status register of the REG and evaluate the reason for the failure condition. With no alarm pending in the REG, the rega-bit is set to ONE. + +- *uib-bits (unspecified indicator bits)* + +These bits are reserved for future use. They shall be set to ONE. + +- *stq (stuffing quats)* + +(stq1m, stq1s, stq2m, stq2s) + +These quats are always used together. Either none or two stuffing quats are inserted, depending on the relation of the timing between the two transmit directions. The values of the stuffing quats used are left as a choice to the individual vendors. Stuffing bits are not scrambled. + +- *indic- and indr-bit (ready to receive indicator at the LTU and NTU resp.)* + +These bits are set to ZERO by the respective HDSL transceiver to indicate to the distant HDSL transceiver that it is ready to receive data, in all other conditions the indic- and indr-bit will be set to ONE. + +NOTE – The indic- and indr-bit in the HDSL frame overhead are different and not to be confused with the status indicators INDC and INDR used inside the HDSL transceivers during the start-up procedure as described in 5.6. + +### 5.4.3 Scrambling method + +The HDSL transceiver systems use the same self synchronizing scrambling procedure as the 2B1Q transmission system for ISDN-BA as defined in Annex A/G.960 [2]. The data stream with exception of the 14 bits of the sync word and the stuffing bits is scrambled by means of a 23rd order polynomial prior to encoding. + +- For the direction NTU → LTU the polynomial shall be $x^{-23} \oplus x^{-18} \oplus 1$ , where the sign $\oplus$ stands for modulo 2 summation. +- For the direction LTU → NTU the polynomial shall be $x^{-23} \oplus x^{-5} \oplus 1$ . +- The binary data stream is recovered in the receiver by applying the same polynomial to the scrambled data. Figure 10 illustrates block diagrams for the scramblers and descramblers. + +#### NTU (REG-R) Transmit Scrambler (NTU to LTU) + +![Diagram of NTU (REG-R) Transmit Scrambler (NTU to LTU).](7f5df81190b8dc50dad2604562ae0715_img.jpg) + +The diagram shows a transmit scrambler for NTU (REG-R) from NTU to LTU. It consists of a series of delay blocks labeled $x^{-1}$ . The input data $D_i$ is XORed with a feedback signal to produce the scrambled data $D_s$ . The feedback signal is derived from $D_s$ through a series of delays, with taps at $x^{-18}$ and $x^{-23}$ being XORed back into the input. The output is $D_s \cdot x^{-23}$ . + +$$D_s = D_i \oplus D_s \cdot x^{-18} \oplus D_s \cdot x^{-23}$$ + +Diagram of NTU (REG-R) Transmit Scrambler (NTU to LTU). + +#### LTU (REG-C) Transmit Scrambler (LTU to NTU) + +![Diagram of LTU (REG-C) Transmit Scrambler (LTU to NTU).](6629e8a87e7552e2454b7c3e9f6d73a0_img.jpg) + +The diagram shows a transmit scrambler for LTU (REG-C) from LTU to NTU. It consists of a series of delay blocks labeled $x^{-1}$ . The input data $D_i$ is XORed with a feedback signal to produce the scrambled data $D_s$ . The feedback signal is derived from $D_s$ through a series of delays, with taps at $x^{-5}$ and $x^{-23}$ being XORed back into the input. The output is $D_s \cdot x^{-23}$ . + +$$D_s = D_i \oplus D_s \cdot x^{-5} \oplus D_s \cdot x^{-23}$$ + +Diagram of LTU (REG-C) Transmit Scrambler (LTU to NTU). + +#### LTU (REG-C) Receive Descrambler (NTU to LTU) + +![Diagram of LTU (REG-C) Receive Descrambler (NTU to LTU).](382a9c9e4816bd229191ab4591424dd8_img.jpg) + +The diagram shows a receive descrambler for LTU (REG-C) from NTU to LTU. It consists of a series of delay blocks labeled $x^{-1}$ . The scrambled data $D_s$ is input and XORed with a feedback signal to produce the unscrambled output $D_o$ . The feedback signal is derived from $D_o$ through a series of delays, with taps at $x^{-18}$ and $x^{-23}$ being XORed back into the input. The output is $D_o$ . + +$$D_o = D_s \cdot (1 \oplus x^{-18} \oplus x^{-23})$$ + +Diagram of LTU (REG-C) Receive Descrambler (NTU to LTU). + +#### NTU (REG-R) Receive Descrambler (LTU to NTU) + +![Diagram of NTU (REG-R) Receive Descrambler (LTU to NTU).](896e86ed12aff206d302c64f2e3091fa_img.jpg) + +The diagram shows a receive descrambler for NTU (REG-R) from LTU to NTU. It consists of a series of delay blocks labeled $x^{-1}$ . The scrambled data $D_s$ is input and XORed with a feedback signal to produce the unscrambled output $D_o$ . The feedback signal is derived from $D_o$ through a series of delays, with taps at $x^{-5}$ and $x^{-23}$ being XORed back into the input. The output is $D_o$ . + +$$D_o = D_s \cdot (1 \oplus x^{-5} \oplus x^{-23})$$ + +Diagram of NTU (REG-R) Receive Descrambler (LTU to NTU). + +T1528910-98 + +- $D_s$ Scrambled (s) data +- $D_i$ Unscrambled input (i) data +- $D_o$ Unscrambled output (o) data +- $x^{-n}$ Delay of n bit periods +- $\oplus$ Logical exclusive or +- $\cdot$ Multiplication + +**Figure 10/G.991.1 – Scramblers and descramblers** + +## 5.5 HDSL embedded operations channel (eoc) + +This subclause specifies the requirements for the embedded operations channel. Thirteen of the available 50 HDSL overhead bits (HOH) as shown in Tables 3, 4 and 5 are used for the eoc-application and present a complete eoc-frame synchronized to the corresponding HDSL frame. The structure of each single eoc-frame is as shown in Table 8 and discussed below. + +**Table 8/G.991.1 – HDSL eoc frame structure** + +| Bit position | No. of bits | Description | Remarks | +|--------------|-------------|--------------------------------------|----------------------------| +| 1, 2 | 2 | Address | Can address four locations | +| 3 | 1 | Data (ZERO)/ message (ONE) indicator | | +| 4 | 1 | Odd (ONE)/even (ZERO) byte | Multibyte transmission | +| 5 | 1 | Unused | | +| 6-13 (Note) | 8 | Information field | 256 opcodes, 8 bits data | + +NOTE – eoc06 contains the MSB and eoc13 the LSB of the opcode/data as described in Tables 9 to 11. + +### 1) *The address field* + +The first two bits (eoc01 and eoc02) allow for unique addressing of four network elements. This Recommendation specifies requirements for only three locations, NTU, REG and LTU. The LTU address is "11" and can be considered as the eoc-master. + +The NTU and REG (if present) addresses are "00" and "10" (eoc01, eoc02) respectively, and can be considered as the addresses of the slaves. + +The address in a return echo should be set to that of the responding unit. + +### 2) *The data/message indicator bit* + +The data/message indicator bit shall be set to ONE when the information field contains the operation code for an HDSL eoc-message. + +The data/message indicator bit shall be set to ZERO when the information field contains data, either binary or ASCII. + +### 3) *Odd/even Byte* + +The "Odd Byte"/"Even Byte" field is used as follows: + +For the first byte of data to be either read or written, the eoc04 bit is set to ONE to indicate "Odd Byte", for the next byte eoc04 is set to ZERO to indicate "Even Byte" and so on, alternately. This field is used to speed up data read and write by eliminating the need for intermediate codes to indicate to the far end that the previous byte was successfully received. + +### 4) *Unused bit* + +Set to ONE. + +### 5) *Information field* + +Up to 256 different messages or 8 bit of binary or ASCII data may be encoded in the information field. + +### 5.5.1 Functions of the HDSL eoc + +The LTU (master) sends commands to the NTU/REG (slave) to perform certain functions. Some of these functions require the slave to activate changes in the circuitry (e.g. to either loopback or send crc bits that are corrupted). Other functions can be invoked to read from and write to data registers located in the slave. + +Some of these commands are "latching", meaning that a subsequent command will be required to release from this state. Thus multiple HDSL eoc-initiated actions can be in effect simultaneously. A separate command "Return to Normal" together with the appropriate address shall be used to unlatch all latched states in the REG or the NTU. If no message is pending for both the NTU and the REG (idle state), the "Return to Normal" message shall be sent by the LTU together with the NTU-address "00". If no opcode has to be sent during a latched state the LTU may send the "Hold State" message. + +The NTU, if not properly addressed, shall insert the "Hold State" message with the NTU-address "00" in the direction NTU → LTU. Normally if the REG has been addressed and its eoc-unit is working properly, this NTU message will be overwritten in the REG. In the case, the eoc-unit in the REG is unable to react (due to improper function), receiving the "Hold State" message from the NTU indicates to the LTU, that the REG is not working properly, although the messages are transported over the whole link down to the NTU. + +The regenerator REG is transparent to all messages in the direction LTU → NTU, including messages addressing the regenerator itself. In the direction NTU → LTU the regenerator is transparent as long as no messages addressing the regenerator, are received. In this case, any message from the NTU in the direction NTU → LTU is overwritten, depending on the action required by the eoc-message for the regenerator. + +The complete set of commands is listed in Table 9 and described in 5.5.5. + +**Table 9/G.991.1 – eoc opcode messages** + +| Hex-code | Opcode description | +|----------|-----------------------------------------------------| +| 06 | Unable to Comply (UTC) | +| 07 | Return to Normal | +| 08 | Loopback of application frame at NTU (Note 1) | +| 10 | Hold State | +| 19 | Analogue Loopback in REG (Note 1 and Note 2) | +| 20 | Request Corrupted CRC NTU/REG-R (Note 1 and Note 3) | +| 22 | Request Corrupted CRC REG-C (Note 1) | +| 28 | Request End of Corrupted CRC NTU/REG-R (Note 3) | +| 29 | Request End of Corrupted CRC REG-C | +| 3F | Notify Corrupted CRC NTU/REG-R (Note 1 and Note 3) | +| 50 | Notify Corrupted CRC REG-C (Note 1) | +| 5F | Notify End of Corrupted CRC NTU/REG-R (Note 3) | +| 60 | Notify End of Corrupted CRC REG-C | +| 9F | End of Data | +| AF | Next Byte | + +**Table 9/G.991.1 – eoc opcode messages (concluded)** + +| Hex-code | Opcode description | +|-----------------|-------------------------------------------------------| +| D0-DF | Write Data Register (numbers 0 to F) NTU/REG (Note 3) | +| E0-EF | Read Data Register (numbers 0 to F) NTU/REG (Note 3) | +| F0-F3 | Vendor defined | + +NOTE 1 – Latching; this means that a release message is required to cancel the function. +NOTE 2 – Due to the used transmission system, separate loopbacks for each pair have to be set up in the regenerator. The OAM unit in the LTU has to assure that the individual loopback is closed, before acknowledging the proper operation to the application interface. +NOTE 3 – This opcode is used for messages concerning the NTU or the REG. A distinction between both is possible by the address contained in the message. +NOTE 4 – No need has been identified for the messages 18, 30, 38, 6F, 7F in Europe. They may be used by network operators outside Europe, e.g. in North America as defined in the Committee T1 Technical Report [B3]. All other messages are reserved for future applications. + +### **5.5.2 HDSL eoc acknowledgement protocol** + +The LTU is the master of the HDSL eoc and always issues the commands. The slave responds to the properly addressed messages by acknowledging to the master that the message was received correctly. Thus, the HDSL eoc protocol operates in a command/response mode with the master issuing the command and the slave responding. + +Pair-specific messages shall be transmitted and acknowledged on the addressed pair only. In the slave (NTU/REG) the evaluation and the acknowledgment is carried out separately for each HDSL transceiver system (subsystem), i.e. every subsystem echoes the received eoc-message independently of the code on the other subsystems. + +This subsystem oriented handling of the eoc-protocol allows for a regenerator implementation based on independent modules for each pair. This general principle is also provided in the NTU, i.e. messages which require an action on a single pair (e.g. all CRC functions, read noise margin) are executed only on those pairs, where the message has been received correctly. + +Global messages, not addressing functions of a single pair, like loopback in the NTU, may be sent over all pairs in parallel or over one single pair, as selected by the LTU. The NTU will evaluate the message on one single pair only, which may be selected by monitoring the eoc for a valid global message or by any performance monitoring. The NTU, after receiving three consecutive valid messages on the selected pair, enters the corresponding state and performs the appropriate action. The acknowledgment of the received messages shall be sent over all pairs in parallel and the LTU evaluates the acknowledgment on one single pair only. So the LTU and the NTU may evaluate the messages on different pairs. In the REG, due to the pair-specific implementation, no difference exists between global and pair-specific messages. The LTU has to take care, that all individual loopbacks are activated before indicating an active loopback 1A. + +Three types of responses are allowed from the slave, and thus, there are three protocol states allowed on the HDSL eoc. At any time the HDSL eoc will be in one of the three protocol states, and can switch from one state to another during a message. + +The three protocol states are: + +- 1) message/echo-response protocol state; +- 2) message/unable to comply (UTC)-response protocol state; +- 3) message/data-response protocol state. + +#### **5.5.2.1 Message/echo-response protocol state** + +To acknowledge a properly addressed message from the LTU, the slave (NTU or REG) responds to a received HDSL eoc-message by returning identical HDSL eoc frames back to the LTU. This response procedure is termed "echoing" the HDSL eoc-message. The combination of the LTU sending the HDSL eoc frame and the slave echoing the frame back comprises the message/echo-response protocol state. + +To assure the validity of the message, the slave must receive three identical, and consecutive HDSL eoc frames before activating the requested function. In this way, the transmitted HDSL eoc-messages received by the slave can be assumed to be correct with high probability. + +For the LTU to confirm correct reception of the message by the slave, the message is repeated until the LTU receives three identical and consecutive echoes. This serves as an implicit acknowledgment to the LTU that the slave has correctly received the transmitted message and is acting on it. This completes the command/response protocol mode. + +In summary, the HDSL eoc-protocol requires that the LTU transmits a message continuously until it receives three identical and consecutive echoes of the HDSL eoc frame originally transmitted. + +The LTU cannot start sending a new message to the slave until the previous message on the HDSL eoc is acknowledged and the command/response protocol for that message is completed. This "one message outstanding" rule automatically eliminates HDSL eoc contention problems that may occur between NTU and REG. + +A HDSL core divides the payload between two or three-pairs. The rules stated previously, requiring three consecutive identical receptions of a message or an acknowledgment, apply to a single pair. That is, the message or acknowledgment must be received three times consecutively and identically over the same pair. + +Thus the following requirements apply: + +- 1) Only one message, under the control of the LTU, shall be outstanding (not yet acknowledged and confirmed) on the HDSL eoc at any time. +- 2) In order to cause the desired action in the slave, the LTU shall continue to send the message until it receives at least three identical consecutive HDSL eoc frames from the slave over one-pair. This shall constitute an acknowledgement to the LTU that the slave received the transmitted message correctly. +- 3) For non-latching conditions the LTU shall after the receipt of the three valid echoes continuously send the activating message or, alternatively, it shall switch to sending the "Hold State" message. +- 4) The slave shall initiate action when, and only when, three identical, consecutive, and properly addressed HDSL eoc frames, that contain a message recognized by the slave, have been received over the one-pair. +- 5) The slave shall respond to all properly addressed received messages. The response shall be an echo of the received HDSL eoc frame towards the LTU. +- 6) Any reply or echoed HDSL eoc frame shall be sent in the next available returning HDSL eoc frame. + +- 7) The loopback (in the NTU/REG) and request/notify corrupted CRC commands shall be latching, permitting multiple HDSL eoc-initiated actions to be in effect simultaneously. +- 8) To unlatch all latched conditions, the message "Return to Normal" shall be transmitted by the LTU. When the slave correctly receives the "Return to Normal" message from the LTU (three times identically and consecutively), it shall unlatch all currently latched conditions initiated by prior HDSL eoc-messages. +- 9) The slave shall not send autonomous messages. + +#### 5.5.2.2 Unable to comply mode of operation + +When the slave does not support a properly addressed message that it has received three times identically and consecutively over the active pair, the slave responds with the UTC HDSL eoc response message instead of a third identical and consecutive echo. The slave shall then switch over to the message/UTC-response protocol state. + +The slave also enters the message/UTC-response control state, if a message has been received that is not applicable in the current status of the command/response mode of operation, e.g. if a "Next Byte" message is detected without having received a "Read Data Register" opcode. + +An error in transmission could corrupt the UTC response. This would make the LTU conclude that it was a proper message and was acknowledged. To reduce the probability of this happening, the UTC code is selected to have a Hamming distance of at least two from all other codes except the idle code. + +Thus, the following requirements apply: + +- 1) If the NTU/REG does not support the message in a properly addressed HDSL eoc frame, it shall return the UTC message with its own address rather than echo on the third and all subsequent consecutive reception of that same correctly addressed HDSL eoc frame. +- 2) The sending by the NTU/REG and the subsequent receipt by the LTU of three identical, consecutive, properly addressed UTC messages shall constitute notification to the LTU that the NTU/REG does not support the requested function, at which time the LTU may abandon its attempt. + +The LTU may, of course, abandon the attempt at any time before the UTC is received (for example, if the "Return to Normal" or "Hold State" message is sent by the LTU). + +- 3) The NTU/REG exits the UTC mode of operation only after receiving three consecutive "Return to Normal " messages from the LTU. + +### 5.5.3 The HDSL eoc data read/write mode + +For data transmission, bit three and bit four are used in combination. Bit three will be set to data (ZERO) only when data (rather than an opcode) are transmitted. Bit four makes multibyte data transmission more efficient. It will denote whether the data byte being transmitted is an "Odd Byte" or "Even Byte". As described in the next subclause, with this procedure there is a message/echo-response state to access the register, and following that one byte of data can be transferred for each message/data-response state. The LTU can either write data into the NTU/REG memory, or read data from the NTU/REG. + +#### 5.5.3.1 Data read protocol + +If the LTU is reading data from the NTU/REG it will send an appropriate read opcode message to the NTU/REG that specifies the register to be read. After receiving three identical and consecutive acknowledgments, the LTU will request for the first byte to be sent from the NTU/REG by sending "Next Byte" messages with bit four set to ONE indicating a request for an "Odd Byte". The NTU/REG will respond to these "Next Byte" messages by echoing them until it has received three + +such messages consecutively and identically. Beginning with the third such reception, the NTU/REG will respond by sending the first byte of the register in an HDSL eoc data frame with bit four set to ONE to indicate "Odd Byte". (A data frame that contains data in the information fields is distinguished from a frame containing an opcode by setting bit three to ZERO.) The LTU continues to send the "Next Byte" message byte with bit four set to "Odd Byte", and the NTU/REG continues to respond with a data frame containing the first byte of data and bit four equal to "Odd Byte", until the LTU has received three consecutive and identical data frames with bit four set to "Odd Byte". + +If there is more data to be read, the LTU requests the second byte of data by sending "Next Byte" messages with bit four set to ZERO ("Even Byte"). The NTU/REG echoes all messages received until three such "Next Byte" messages have been received, and on the third consecutive and identical "Next Byte" message, the NTU/REG starts sending data frames containing the second byte of the register with bit four set to ZERO. The LTU continues to send the "Next Byte" message with bit four set to "Even Byte", and the NTU/REG continues to respond with a data frame containing the second byte with bit four set to "Even Byte", until the LTU has received three consecutive and identical data frames with bit four set to "Even Byte". Note that once the NTU/REG is in the Data Read mode, to continue reading data, the only message that the LTU is allowed to send is the "Next Byte" message with bit four toggling. + +If the LTU wants to end the data read mode (either normally or abnormally), it shall send the "Hold State" or "Return to Normal" message depending upon if the LTU wants to retain any latched state or not. If the NTU/REG receives any other message, three times consecutively and identically, it shall go into the UTC mode. + +The process continues for the third and all subsequent bytes with the value of bit four toggling from "Odd Byte" to "Even Byte" or vice versa, on each succeeding byte. Each time bit four is toggled, the NTU/REG echoes for two correct frames, and starts sending the data frame on the third reception. The process ends only when all data in the register have been read. If the LTU continues to send the "Next Byte" message, with the fourth bit toggled, then the NTU/REG will send an "End of Data" message. It is assumed that the LTU knows how many bytes of data to expect, but this is a safety measure to end the process. Thus, each time a data byte is received satisfactorily by the LTU, the LTU will send a "Next Byte" code with bit four set appropriately until it is satisfied that it has received all the bytes, or, until it has received three identical and consecutive "End of Data" messages with bit three set to ONE indicating opcode. Thus, it is possible to accommodate data of many bytes. + +The data read mode ends, and the NTU/REG releases the register, when the LTU switches over to a known state with the "Hold State" message or "Return to Normal" message depending on whether it wants the latched conditions held or not. + +#### 5.5.3.2 HDSL eoc data read mode requirements + +The protocol state sequence for the data read mode is as follows: + +- 1) *message/echo-response protocol state* + - a) The HDSL eoc shall enter the data read mode of operation when the LTU sends a "Read Data" message for a specific register. + - b) The response to this message shall be the echo response. +- 2) *message/data-response protocol state* + - a) Upon receiving three identical and consecutive echo responses that match the register-specific "Read Data" message, the LTU shall send the "Next Byte" message. At this time, bit three shall be set to ONE to indicate an opcode message, and bit four shall be set to ONE to indicate "Odd Byte". + +- b) On receiving the "Next Byte" message, the NTU/REG shall echo the message until it receives it three times consecutively and identically. On the third identical and consecutive reception, the NTU/REG response shall change from the echo response to an HDSL eoc data frame containing the data byte requested. For this frame, bit three shall be set to ZERO to indicate that the information field contains data, and bit four shall be set to ONE. +- c) If the data requested by the LTU is retrieved from a one byte register, when the LTU has received three identical and consecutive HDSL eoc data frames containing the data byte, the "Return to Normal" message or "Hold State" message shall end the data read mode. +- d) If the data requested by the LTU is contained in a register two or more bytes long, the LTU shall initiate additional HDSL eoc protocol states. It shall continue sending the "Next Byte" message with bit three set to ONE, but bit four will be toggled between ZERO and ONE as each byte of data is successfully received (three identical, consecutive echoes). Each time there is a change in bit four the NTU/REG shall start echoing the message, while remaining in the data read mode. On the third identical and consecutive reception, the NTU/REG shall switch to sending a data frame with the next byte of data in the information field. + +##### 3) *message/echo-response protocol state* + +When the LTU has completed its requirements for reading data, it shall start sending the "Hold State" message or "Return to Normal" message to end the data read mode. + +#### 5.5.3.3 Data write protocol + +If the LTU wants to write data into the NTU/REG's memory, it will send a "Write Data" message to the NTU/REG that identifies the required register to be written to. When the NTU/REG acknowledges with an echo message, three times identically and consecutively, the LTU will send the first byte of data. The NTU/REG will acknowledge the receipt of the byte with an echo of the message. After the LTU is satisfied with three identical and consecutive correct echo responses, it will start sending the next byte of data. Each time the LTU receives three identical and consecutive correct data echo responses, it will switch to sending the next byte of data. It will also toggle the odd/even bit accordingly. There is no need for sending "Next Byte" messages in the write mode. The LTU will end the write mode with the "End of Data" message indicating to the NTU/REG to release the register and to end the data write mode. + +The contents of the addressed register in the NTU/REG are overwritten only, if the number of transmitted bytes equals the size of the addressed register and if the data write mode has been properly finished by sending the "End of Data" message by the LTU. + +In any other case, i.e. if the number of transmitted bytes is higher or lower than defined, or if the data write mode is not properly finished, the NTU/REG enters the UTC mode and the content of the corresponding register remains unchanged. + +If the LTU abnormally wants to end the data write mode, it shall send the "Hold State" or "Return to Normal" message, depending on if the LTU wants to retain any latched state or not. If the NTU/REG receives any other message, three times consecutively and identically, it shall enter the UTC mode. + +#### 5.5.3.4 HDSL eoc data write mode requirements + +The protocol state for the data write mode is always message/echo-response. The message field can contain a command or data. + +- 1) *message (command)/echo (command)-response protocol state* + - a) The HDSL eoc shall enter the data write mode of operation when the LTU sends a "Write Data" message for a specific register. + - b) The response by the NTU/REG to this message shall be the echo response. + - c) This protocol state shall be repeated until the LTU receives three identical and consecutive HDSL eoc frames containing the correct echo response. +- 2) *message (Data)/echo (Data)-response protocol state* + - a) Upon receiving three identical consecutive echo responses that match the register-specific "Write Data" message, the LTU shall send a data frame with the first byte of data and with bit three set to ZERO (indicating that the information field contains data) and bit four set to ONE (indicating "Odd Byte"). + - b) The NTU/REG shall respond to this transmission with the echo response. + - c) The data byte shall be written by the NTU/REG unit upon receiving the data byte three times identically and consecutively. + - d) This protocol state shall be repeated until the LTU receives three identical and consecutive HDSL eoc frames containing the correct echo response. + - e) If the LTU is writing to a one byte register, the data write mode shall be completed upon the LTU receiving three identical and consecutive echoes of the data byte it had transmitted. + - f) If the LTU is writing to a multibyte register, the LTU shall continue sending additional bytes of data, while toggling bit four for each byte of data sent successfully. + - g) When the LTU has no more bytes of data to write, the LTU shall send a "End of Data" message to release the NTU/REG from the data write protocol state. + +### 5.5.4 HDSL eoc-message list + +The HDSL eoc protocol uses various messages listed in Table 9 for activating various functions at the NTU/REG. The "Read Data" and "Write Data" commands can support up to 16 registers each. The commands and the corresponding encoding used in this Recommendation, are shown in Tables 10 and 11. The register that a "Read Data" or "Write Data" message operates on is specified as a subfield of the "Read Data" or "Write Data" opcode. Additional message opcodes have been reserved for future standardization. + +Some actions initiated in the NTU/REG by HDSL eoc-messages, such as loopbacks, and intentional corrupted CRC are latching. Latching means that a different message is required to cancel the function. This permits the HDSL eoc to exercise multiple functions simultaneously, in spite of the "one message outstanding" rule. All latched functions may be unlatched with the "Return to Normal" HDSL eoc-message. The "Return to Normal" message returns the NTU/REG to a known state. Repetition of this message continues to hold the NTU/REG in this known state. Hence, the "Return to Normal" message is also defined as the "idle code" for the NTU/REG. On the other hand, if all the latched functions were to be maintained in their latched state, the "Hold State" command is sent. + +- 1) The LTU shall continuously send the activating message after the receipt of the three valid echoes or, alternatively, it shall switch to sending the "Hold State" message if it wants to maintain latched conditions. +- 2) The "Loopback" and "Request/Notify corrupted CRC" commands shall be latching, permitting multiple HDSL eoc-initiated actions to be in effect simultaneously. + +- 3) To release all latched conditions, a separate message "Return to Normal" shall be transmitted by the LTU. When the NTU/REG correctly receives the "Return to Normal" message from the LTU (three times identically and consecutively), it shall unlatch all currently latched conditions initiated by prior HDSL eoc-messages. + +### 5.5.5 HDSL eoc-message set requirements + +The HDSL eoc-message set is shown in Table 9. The actions taken by the NTU/REG and LTU in response to correctly received HDSL eoc-messages shall be as follows: + +- 1) *Unable to Comply (UTC)* + +The NTU/REG shall send this message when it receives an HDSL eoc-message (three times consecutively and identically) that the NTU/REG cannot perform, either because it does not recognize or has not implemented the command, or because the command is unexpected given the current state of the HDSL eoc operations (e.g. the command indicates that the information field contains data, but the command was not preceded by a "Write Data" command). + +- 2) *Return to Normal* + +This message shall release all outstanding latched conditions at the NTU/REG initiated by prior HDSL eoc-messages. The function of the "Return to Normal" message may be used as an eoc reset function for the NTU/REG. Therefore, the proper evaluation of this message in a single NTU/REG subsystem results in a reset of all pending functions in this subsystem. This code sent with the NTU address "00" shall also be sent during idle states. + +- 3) *Loopback of application frame at NTU* + +This message shall direct the NTU to loopback the application bit stream toward the LTU until cancelled by a "Return to Normal" message. + +- 4) *Hold state* + +This message shall be sent by the LTU to maintain the NTU/REG HDSL eoc-processor and any active HDSL eoc controlled operations in their present state. + +- 5) *Analogue Loopback 1A in REG* + +This function directs the REG to loopback the user-data bit stream toward the LTU. This is a transparent loopback. Since this is a function of each individual subsystem REG, the LTU must take care, that these messages are acknowledged by each individual subsystem. + +- 6) *Request Corrupted CRC (Note 1)* + +Sometimes the appearance of error free transmission may result because the CRC circuit is not functioning properly. Hence, when the performance monitoring circuit is suspected of malfunction, corrupted CRCs can be sent to test the CRC logic as well as the circuits that collect, process and store performance data. + +- 6a) *Request Corrupted CRC NTU (Note 2)* + +- *No REG Present* + +Corrupted CRCs are requested to be sent from the NTU to test the CRC checking circuit at the LTU until cancelled with the "Request End of Corrupted CRC NTU" message. + +- *REG Present* + +Corrupted CRCs are requested to be sent from the NTU to test the CRC checking circuit at the REG-C until cancelled with the "Request End of Corrupted CRC NTU" message. This results in the transmission of an active rcbe-bit by the REG towards the LTU and NTU as soon as corrupted CRCs are detected. + +#### 6b) *Request Corrupted CRC REG-R* (Note 2) + +Corrupted CRCs are requested to be sent from the REG towards the LTU to test the CRC checking circuit at the LTU until cancelled with the "Request End of Corrupted CRC REG-R" message. + +#### 6c) *Request Corrupted CRC REG-C* + +Corrupted CRCs are requested to be sent from the REG towards the NTU to test the CRC checking circuit at the NTU until cancelled with the "Request End of Corrupted CRC REG-C" message. This results in the transmission of an active febe-bit by the NTU towards the LTU as soon as corrupted CRCs are detected. + +#### 7a) *Request End of Corrupted CRC NTU* (Note 2) + +This message shall request the NTU to stop sending corrupted CRCs towards the REG or LTU as applicable. + +#### 7b) *Request End of Corrupted CRC REG-R* (Note 2) + +This message shall request the REG to stop sending corrupted CRCs towards the LTU. + +#### 7c) *Request End of Corrupted CRC REG-C* + +This message shall request the REG to stop sending corrupted CRCs towards the NTU. + +#### 8a) *Notify Corrupted CRC NTU* (Note 2) + +###### – *No REG Present* + +This message shall notify the NTU that intentionally corrupted CRCs will be sent towards the NTU by the LTU. This message shall be used in the NTU to disable any alarm indication circuitry activated by the detection of corrupted CRCs. The febe-bit towards the LTU shall be still active however. + +##### – *REG Present* + +This message shall notify the NTU that intentionally corrupted CRCs will be sent towards the NTU by the REG. This message shall be used in the NTU to disable any alarm indication circuitry activated by the detection of corrupted CRCs. The febe-bit towards the LTU shall be still active however. + +#### 8b) *Notify Corrupted CRC REG-R* (Note 2) + +This message shall notify the REG that intentionally corrupted CRCs will be sent towards the REG by the LTU. This message shall be used in the REG to disable the transmission of an active rrbe-bit towards the NTU, as soon as corrupted CRCs are detected from the LTU. The rrbe-bit towards the LTU shall be still active however. + +#### 8c) *Notify Corrupted CRC REG-C* + +This message shall notify the REG that intentionally corrupted CRCs will be sent towards the REG by the NTU. This message shall be used in the REG to disable the transmission of an active rcbe-bit towards the NTU, as soon as corrupted CRCs are detected from the NTU. The rcbe-bit towards the LTU shall be still active however. + +#### 9a) *Notify End of Corrupted CRC NTU* (Note 2) + +This message shall notify the NTU that the LTU or REG has stopped sending intentionally corrupted CRCs and that the NTU may enable again any alarm circuitry detecting corrupted CRCs. + +#### 9b) *Notify End of Corrupted CRC REG-R (Note 2)* + +This message shall notify the REG that the LTU has stopped sending intentionally corrupted CRCs and that the REG may enable again the transmission of a valid rrbe-bit towards the NTU when detecting corrupted CRCs from the LTU. + +#### 9c) *Notify End of Corrupted CRC REG-C* + +This message shall notify the REG that the NTU has stopped sending intentionally corrupted CRCs and that the REG may enable again the transmission of a valid rcbe-bit towards the NTU when detecting corrupted CRCs from the NTU. + +#### 10) *End of Data* + +This message shall be sent by the LTU after it has written all bytes of data to the NTU/REG and by the NTU/REG when the LTU requests more bytes than are available in the NTU/REG register during a data read procedure. + +##### 11) *Next Byte* + +This message shall be sent by the LTU in the data read mode after the NTU/REG has acknowledged the previously sent "Read Data" command. This message shall be continually sent by the LTU when it is in the Data Read mode until all data have been read. This message, coupled with the toggling of bit four, allows multi-byte data to be read. + +#### 12) *Write Data (Register No.)* + +This message shall be sent by the LTU to set the NTU/REG in a mode to receive data in the register specified. The number of the register at the NTU/REG that shall receive data is encoded in the command itself. After receiving this message correctly, the NTU/REG shall enter the data write mode, ready to receive the data contained in the data messages to follow, and store the data in the register number encoded in the command. + +#### 13) *Read Data (Register No.)* + +This message shall be sent by the LTU to set the NTU/REG in a mode to read the data in the register specified. The number of the register at the NTU/REG from which the data are to be read is encoded in the command itself. After receiving this message correctly, the NTU/REG shall enter in the data read mode and transmit data from the register encoded in the command, one byte at a time, in response to successive "Next Byte" messages (with changes in bit four) from the LTU. + +NOTE 1 – No specific algorithm for the corruption is to be defined. + +NOTE 2 – For the messages signed by indices a) and b) the same opcode is used. The equipment concerned is indicated by the address contained in the message. + +### 5.5.6 Data registers in the NTU and in regenerators + +The NTU and the regenerator each contain 16 registers. These registers can be used for read only or for read and write operations. The registers used inside Europe are defined in Tables 10 and 11. The registers Nos.1 to 9 may be used by network operators outside Europe, e.g. in North America as defined in the Committee T1 Technical Report [B3]. The register F is not used at present. Only the registers E in the NTU and C, D and E in the REG are individual for each transceiver of a two or three-pair system. All other registers contain equipment relevant data and are available over all pairs in parallel. Individual registers (register D) at the REG are required for equipment identification when separate regenerators are used in each pair. + +**Table 10/G.991.1 – eoc data registers for the NTU** + +| Reg No.
(Hex) | Use | Length | Name | Description | +|--------------------------|------------|---------------|--------------------------|-----------------------------| +| A | R | Note | NTU status | NTU status information bits | +| B | R/W | Note | NTU configuration | NTU configuration bits | +| D | R | Note | Equipment identification | | +| E | R | 1 byte | Noise margin | | + +R Read Data +W Write Data +NOTE – The number of bytes and the contents of the register, as well as the encoding of the different bits, is left to the individual network operator. + +**Table 11/G.991.1 – eoc data registers for regenerators** + +| Reg No.
(Hex) | Use | Length | Name | Description | +|--------------------------|------------|---------------|--------------------------|-----------------------------| +| A | R | Note | REG-status | REG status information bits | +| C | R | 1 byte | noise margin REG-C | | +| D | R | Note | Equipment identification | | +| E | R | 1 byte | Noise margin REG-R | | + +NOTE – The number of bytes and the contents of the register, as well as the encoding of the different bits, is left to the individual network operators. + +### **5.5.7 Noise margin** + +#### **5.5.7.1 General** + +For the evaluation of the noise margin a Gaussian noise is assumed. The noise value is calculated based on a sample taken each second for each pair separately. The evaluating range is between +27 dB and –5 dB, where 0 dB indicates the noise margin for which a BER of $10^{-7}$ for each pair is expected. The accuracy of the values shall be 1 dB in the range between +5 dB and –5 dB. + +#### **5.5.7.2 Coding of the noise margin values** + +The coding shall use a logarithmic law and have an increment of 0.5 dB. It uses one byte from which the first bit (MSB) and the second bit are identical and indicate the sign. The remaining six bits are used for the value of the noise margin, as shown in Table 12. + +**Table 12/G.991.1 – Coding of noise margin values** + +| Noise margin | MSB LSB
1234 5678 | Remark | +|---------------------|------------------------------|--------------------------| +| +31.5 dB | 0011 1111 | Not relevant | +| +27.5 dB | 0011 0111 | | +| +27.0 dB | 0011 0110 | Expected BER $< 10^{-7}$ | +| +0.5 dB | 0000 0001 | | +| 0 dB | 0000 0000 | Expected BER $10^{-7}$ | +| –0.5 dB | 1111 1111 | Expected BER $> 10^{-7}$ | +| –5.0 dB | 1111 0110 | | +| –5.5 dB | 1111 0101 | Not relevant | +| –31.5 dB | 1100 0001 | | + +## **5.6 Start-up procedure** + +### **5.6.1 General** + +#### **5.6.1.1 Start-up** + +The start-up procedure is designed as a local procedure for each pair, it is a process characterized by a sequence of signals produced by the NTU, the LTU and the REG. Start-up results in an establishment of two-way transmission (if possible) between the application interfaces, i.e. synchronization of the receivers, training of the echo cancellers and training of the equalizers to the point that the requirements for reliable communications are met. Also, tip-ring polarity reversal and pair interchanges are automatically detected and compensated at the NTU. It is the task of the operation and maintenance block to detect when the start up procedure for all pairs is completed and to initiate a transparent transmission of user data. + +#### **5.6.1.2 Activation of HDSL transceiver pairs** + +Activation is the process for the establishment of duplex communication over a single pair. This process is established between the HDSL transceivers at the LTU and the NTU, or between the LTU and the REG-R and the REG-C and the NTU respectively. + +#### **5.6.1.3 Transparency** + +Prior to the completion of activation the transmission is not transparent, the signals that are present at the line interfaces of the HDSL transceivers are special start-up patterns generated by the HDSL transceivers. Each HDSL transceiver shall provide transparent transmission of data to the core function after completion of the individual activation procedure. The output signal of receivers that have not yet entered the Active-Rx State as defined in 5.6.5 and 5.6.6 shall be set to all ONEs. + +The operational status is determined by the application. + +NOTE – Transceivers in a REG are at no time fully transparent in so far as some HOH-bits will be overwritten. + +#### **5.6.1.4 Noise margin** + +The noise margin is estimated at the receivers of LTU, NTU and REG (if provided). This value is used to estimate the Bit Error Ratio (BER) of the received data. + +For applications according to this Recommendation the noise margin is compared to a value of $-5$ dB during the start-up procedure. + +NOTE – This value does not allow data transmission, it is chosen to be in compliance with existing equipment using the noise margin as a criteria for start-up. + +### **5.6.2 Control and status signals** + +The following virtual control and status signals are involved in the activation procedure. They are related to the operation of the individual HDSL transceiver. + +#### **5.6.2.1 Control signals** + +##### **5.6.2.1.1 QUIET** + +QUIET = ONE will cause a transition of the HDSL transceiver from any state (except the Inactive State) to the Deactivated State, where no energy – except remote powering – is transmitted to the line. The QUIET = ONE command will not cause any change if the HDSL transceiver is in the Inactive State. + +##### **5.6.2.1.2 ACTREQ** + +Activation Request (ACTREQ) defaults to ONE at power-up. The HDSL transceiver at the LTU will begin the activation process only if ACTREQ is equal to ONE. + +#### **5.6.2.2 Status signals** + +All of the following status signals are defined per pair. + +##### **5.6.2.2.1 LOSW** + +The absence of the Loss of Sync Word signal (LOSW = ZERO) indicates that HDSL frame synchronization is completed. When LOSW = ONE the receiver has not yet acquired frame synchronization, or it has lost it (see Figures 13, 14 and 15). + +##### **5.6.2.2.2 LOSWT** + +LOSWT = ONE indicates that the frame synchronization has been lost for more than 2. + +##### **5.6.2.2.3 LOS** + +The Loss of Signal signal (LOS = ONE) in the NTU indicates that no signal is detected on the line from the LTU. LOS = ZERO indicates that a signal from the LTU has been detected. + +##### **5.6.2.2.4 LOST** + +The LOST = ONE in the LTU indicates that no signal is detected on the line from the NTU for more than 1. + +##### **5.6.2.2.5 INDC** + +When an HDSL transceiver at the LTU is ready to receive data the indicator INDC is set (INDC = ONE). The condition for INDC = ONE is: + +$$[(\text{LOSW} = \text{ZERO}) \text{ and } (\text{noise margin} > -5 \text{ dB})] \text{ or } [(\text{LOSW} = \text{ZERO}) \text{ and } (\text{T-Act expired})]$$ + +Because of the low noise margin defined for applications referring to this Recommendation the noise margin condition is met in any case, which results in the simple condition: + +$$\text{INDC} = \text{ONE} \text{ is effectively identical to } \text{LOSW} = \text{ZERO}.$$ + +The reason for keeping the above-mentioned multiple condition is to achieve compatibility with existing circuits. + +##### 5.6.2.2.6 INDR + +When an HDSL transceiver at the NTU is ready to receive data the indicator INDR is set (INDR = ONE). The condition for INDR = ONE is: + +$$[(\text{LOSW} = \text{ZERO}) \text{ and } (\text{noise margin} > -5 \text{ dB})] \text{ or } [(\text{LOSW} = \text{ZERO}) \text{ and } (\text{T-Act expired})]$$ + +Because of the low noise margin defined for applications referring to this Recommendation the noise margin condition is met in any case, which results in the simple condition: + +$$\text{INDR} = \text{ONE} \text{ is effectively identical to } \text{LOSW} = \text{ZERO}.$$ + +The reason for keeping the above-mentioned multiple condition is to achieve compatibility with existing circuits. + +NOTE – The internal status indicators INDC and INDR are different from the indc- and indir-bit in the overhead channel as defined in Tables 3, 4 and 5. + +### 5.6.3 Transmitted signals + +The following is the description of the transmitted signals during activation: + +#### 5.6.3.1 Silent + +No signal is transmitted to the line. + +#### 5.6.3.2 S0 signal + +The S0 signal is a two-level signal including the sync word and stuff symbols. The polarity of the stuff quats is arbitrary. The sequence of the stuffing steps is also arbitrary. However, not more than four consecutive frames with the same (plus or minus) stuffing shall be used. The remainder of the two level signal are derived from scrambling an all ONEs sequence and only the sign bit is used to select the level of the signal. The scrambler is operating at the line bit rate and is disabled during the transmission of the HDSL frame sync word and the stuffing bits. The transmitted levels of all symbols (including the stuff quats) in the S0 signal are +3 and -3. + +#### 5.6.3.3 S1 signal + +The S1 signal shall be a framed four-level scrambled signal. The frame shall consist of the HDSL frame sync word, the stuffing bits, the HOH and the payload blocks. The payload blocks shall contain an all ONEs signal replacing the Z-bit and the payload. The scrambler is operating at the full bit rate and is disabled during the transmission of the sync word and the stuffing bits. The transmitted levels are +3, +1, -1 and -3. All HOH-bits transmitted by the LTU and the NTU shall be valid. The REGs shall insert only those HOH-bits originated by themselves, all other HOH-bits shall be set to ONE, until the REG-R enters the Active-R State or REG-C the Active-C State, as defined in 5.6.6, but as long as the REGs are in its Active-R respectively Active-C State they shall be transparent for these HOH-bits. + +#### **5.6.3.4 2B1Q data** + +The 2B1Q data signal shall be a framed and scrambled four-level signal. The frame shall consist of the HDSL frame sync word, the stuffing bits, the valid HOH bits and payload blocks. The payload blocks shall contain valid Z-bits and the payload, which is however application and implementation dependant until the start-up procedure is completed for all used transceiver pairs and the pair identification procedure is completed. The scrambler is operating at the full bit rate and is disabled during the transmission of the sync word and the stuffing bits. The transmitted levels are +3, +1, -1 and -3. + +### **5.6.4 Timers** + +The following timers are involved in the activation procedure of the HDSL transceivers. The timeline of the activation sequence is given in Figure 11 and the timer values are given in Table 13. The precise role of the timers in the start-up procedure is described in 5.6.5. + +#### **5.6.4.1 T1** + +T1 is the duration which the HDSL transceiver at the LTU continues to transmit a S0 signal after it has detected a S0 signal from the NTU. + +#### **5.6.4.2 T2** + +T2 is the duration between the time that the HDSL transceiver at the NTU detects signal from the HDSL transceiver at the LTU and the time that it starts to transmit the S0 signal. + +#### **5.6.4.3 T3** + +T3 is the duration between the time that the HDSL transceiver at the NTU detects the S1 signal from the HDSL transceiver at the LTU and the time that it starts to transmit the S1 signal. + +#### **5.6.4.4 T4** + +T4 is the duration between the time that the HDSL transceiver at the NTU starts to transmit the S0 signal and guaranteed stable timing. + +#### **5.6.4.5 T-Act** + +The activation time for the HDSL transceivers (T-Act) is the time in which the activation procedure in the HDSL transceivers at the LTU, the REG or the NTU should have successfully been completed, starting from the point in time where the HDSL transceiver at the LTU, the REG or the NTU starts to transmit the S0 signal. + +#### 5.6.4.6 Timer values + +The timer values are listed in Table 13. + +**Table 13/G.991.1 – Timer values** + +| Lower bound | Timer | Upper bound | +|-------------|-------|-------------| +| 5 s | T1 | 10 s | +| 1.9 s | T2 | 2.1 s | +| | T3 | 4 s | +| | T4 | 4 s | +| 27 | T-Act | 31 s | + +### 5.6.5 Activation state diagrams + +The following subclauses describe the activation timeline, see Figure 11, and the state diagrams for the HDSL transceivers at the LTU and the NTU, see Figures 13 and 14 respectively. The flow diagram of Figure 12 describes the complete start-up sequence of the link between LTU and NTU without a regenerator. + +![Figure 11/G.991.1 – Activation timeline diagram showing the sequence of events between an LTU and an NTU. The diagram includes state transitions (S0 to S1/DATA) and timer intervals (T1, T2, T3, T4, T-Act).](21327313f7b18a481da0c87a6472a80d_img.jpg) + +The diagram illustrates the activation timeline between an LTU (Line Terminal Unit) and an NTU (Network Terminal Unit). The timeline is divided into two horizontal tracks. The top track for the LTU shows an initial state S0 followed by a transition to state S1/DATA. A 'Restart' event is indicated by a vertical line. The bottom track for the NTU also shows an initial state S0 followed by a transition to state S1/DATA. Various timers are shown as intervals between vertical lines: T1 and T3 are shown on the LTU track; T2 and T4 are shown on the NTU track; and T-Act is shown as a long interval spanning both tracks. The diagram is labeled with 'LTU' and 'NTU' on the left side. + +Figure 11/G.991.1 – Activation timeline diagram showing the sequence of events between an LTU and an NTU. The diagram includes state transitions (S0 to S1/DATA) and timer intervals (T1, T2, T3, T4, T-Act). + +T1528920-98 + +**Figure 11/G.991.1 – Activation timeline** + +![Figure 12/G.991.1 – Flow diagram for start-up](119006c9a930f46881484f2229d3b927_img.jpg) + +``` + +sequenceDiagram + participant LTU + participant DLL + participant NTU + + Note over LTU, NTU: Inactive / Silent / Inactive + LTU-->>DLL: LOS = 1 + NTU-->>DLL: LOS = 1 + + Note over LTU: ACTREQ 0 -> 1 + LTU->>NTU: S0 + Note over NTU: Activating + NTU-->>DLL: LOS = 0 + + Note over LTU: Activating (Note 4) + DLL-->>LTU: LOS = 0 + NTU->>LTU: S0 + + Note over NTU: T2 + Note over LTU: T1 + LTU->>NTU: S1 + Note over NTU: T3 + NTU->>LTU: S1 + + Note over LTU, NTU: HOH + Note over NTU: Active-Rx + NTU-->>LTU: indr (hrp, indr) + LTU-->>NTU: INDR + + Note over LTU: Active-Rx + LTU-->>NTU: indc (HOH) + NTU-->>LTU: INDC (Note 2) + + Note over NTU: Active-Tx/Rx, T-Act + LTU->>NTU: data + NTU->>LTU: data + + Note over LTU: Active-Tx/Rx, T-Act + LTU-->>NTU: INDR (Note 3) + LTU->>NTU: data + NTU->>LTU: data + +``` + +NOTE 1 – After having detected the status indicator INDC, the LTU starts to evaluate the indr- and hrp-bit. If an hrp-bit set to ONE is received no regenerator is present. + NOTE 2 – If the indc = 0 has been received six times consecutively, the NTU becomes transparent for payload blocks. + NOTE 3 – If the indr = 0 has been received six times consecutively, the LTU becomes transparent for payload blocks. + NOTE 4 – Timer T-Act is restarted after reception of S0 from the NTU. + NOTE 5 – Timer T4 is an NTU internal timer and therefore it is not shown in this Figure. + +### Figure 12/G.991.1 – Flow diagram for start-up + +Figure 12/G.991.1 – Flow diagram for start-up + +**5.6.5.1 HDSL transceiver states at the NTU** + +Figure 13 shows a state diagram for the activation of the NTU. When powered on, the NTU is initially in the Inactive State, where its transmitter is silent. When signal power is detected from the LTU, the NTU proceeds to the Activating State and executes the timeline shown in Figure 11. + +It waits T2 = 2 s while transmitting no signal and then starts the timer T-Act and the transmission of S0 and monitors the received signal for S1. Within T4 s from beginning of transmission the timing within the NTU should have reached a stable timing phase. When the NTU detects a valid framed four level data signal it sets LOSW = ZERO, stops timer T-Act and starts timer T3. Before expiry of T3 it has to begin transmitting S1 signal. If the timer T-Act expires before synchronization has been achieved the unit will cease transmission and move to the Deactivated State. + +46 Recommendation G.991.1 (10/98) + +When the receiver in the NTU is ready to accept 2B1Q data, it sets the indicator INDR = ONE and moves to the Active-Rx State. The condition for INDR = ONE is, as described in 5.6.2.2.6, that synchronization is reached (LOSW = ZERO), because the noise margin condition is for applications according to this Recommendation met in any case, due to the low value of -5 dB defined for the noise threshold. + +![Figure 13/G.991.1 – NTU activation state diagram. The diagram shows five states: Deactivated State (Tx: Silent), Inactive State (Tx: Silent), Pending Deactivation State (Tx: 2B1Q data), Active-Rx State (Tx: S1, Rx: ready), and Active-Tx/Rx State (Tx: 2B1Q data, Rx: 2B1Q data). Transitions are triggered by events like Power on, LOS=1, LOS=0, LOSWT=1, T-Act expired, LOSW=0, LOSW=1, INDR=1, INDC=1, and INDC=1 or T-Act expired. A dashed circle represents the Active-Tx State (Tx: 2B1Q data, Rx: not ready).](8a9f4764511ce90622893ec65c065eeb_img.jpg) + +``` + +stateDiagram-v2 + [*] --> InactiveState : Power on + InactiveState --> ActivatingState : LOS = 0 + ActivatingState --> ActiveRxState : INDR = 1 + ActivatingState --> PendingDeactivationState : T-Act expired + ActiveRxState --> PendingDeactivationState : LOSW = 1 + ActiveRxState --> ActiveTxRxState : LOSW = 0 + PendingDeactivationState --> DeactivatedState : LOSWT = 1 + PendingDeactivationState --> ActiveTxRxState : LOSW = 0 + DeactivatedState --> InactiveState : LOS = 1 + ActiveTxRxState --> PendingDeactivationState : INDC = 1 or T-Act expired + ActiveTxRxState --> ActiveRxState : INDC = 1 or T-Act expired + ActiveTxRxState --> DeactivatedState : LOSW = 1 + state "Active-Tx State" as ActiveTxState : Tx: 2B1Q data, Rx: not ready + ActiveTxRxState --> ActiveTxState : INDR = 1 or T-Act expired + ActiveTxState --> PendingDeactivationState : INDC = 1 + state "Deactivated State" as DeactivatedState : Tx: Silent + state "Inactive State" as InactiveState : Tx: Silent + state "Pending Deactivation State" as PendingDeactivationState : Tx: 2B1Q data + state "Active-Rx State" as ActiveRxState : Tx: S1, Rx: ready + state "Active-Tx/Rx State" as ActiveTxRxState : Tx: 2B1Q data, Rx: 2B1Q data + state "Activating State" as ActivatingState : Tx: Silent, S0, or S1 + +``` + +Figure 13/G.991.1 – NTU activation state diagram. The diagram shows five states: Deactivated State (Tx: Silent), Inactive State (Tx: Silent), Pending Deactivation State (Tx: 2B1Q data), Active-Rx State (Tx: S1, Rx: ready), and Active-Tx/Rx State (Tx: 2B1Q data, Rx: 2B1Q data). Transitions are triggered by events like Power on, LOS=1, LOS=0, LOSWT=1, T-Act expired, LOSW=0, LOSW=1, INDR=1, INDC=1, and INDC=1 or T-Act expired. A dashed circle represents the Active-Tx State (Tx: 2B1Q data, Rx: not ready). + +Figure 13/G.991.1 – NTU activation state diagram + +When the overhead channel in the transmitted S1 signal becomes available in the preceding start-up procedure, the status INDR = ONE is conveyed to the LTU by setting the indicator bit *indr* = 0. In the LTU an identical process takes place and *indc* = 0 is received by the NTU in the overhead channel if the LTU has reached its Active-Rx State and is ready to receive 2B1Q data. After the reception of six consecutive indicator bits *indc* = 0 the status indicator INDC is set to ONE and the NTU moves to the Active-Tx/Rx State, where it is fully active, both transmitting and receiving 2B1Q data. + +If it does not detect INDC = ONE before timer T-Act expires, then it will move to the Active-Tx/Rx State anyway, whether synchronization is still being maintained or not. If the NTU has lost synchronization and LOSW = ONE, the system will proceed to the Pending Deactivation State. On the other hand, if synchronization is present at both ends and the LTU has not failed the timeline and not reached its Deactivated State, the timer at the LTU will promptly force that unit into its Active-Tx/Rx State and set INDC = ONE. When INDC = ONE is detected at the NTU, the system will be operational in the Active-Tx/Rx State. If the LTU does not have synchronization, it will move to its Pending Deactivation State and ultimately to the Deactivated State, where it will go to Silent. At this point the NTU will lose synchronization and move to its own Pending Deactivation State. + +Once in the Active-Tx/Rx State, the unit will remain there unless synchronization is lost, or the unit is signalled to go to the QUIET mode or is powered off. If the unit is signalled to go to QUIET mode, it will go to the Deactivated State. If synchronization is lost (LOSW = ONE), the unit will move to the Pending Deactivation State. While in the Pending Deactivation State, the unit attempts to regain synchronization for nominally 2 s. If synchronization is regained in this time (LOSW = ZERO), the unit returns to the Active-Tx/Rx State. If not, LOSWT is set to ONE and the unit enters the Deactivated State. + +After entering the Deactivated State, either due to a period of synchronization word loss (LOSW = ONE), or due to expiration of the timer T-Act, the transmitter in the NTU goes silent and the NTU begins to look for a loss of signal power from the LTU. When a loss of signal (LOS = ONE) is detected, the unit moves immediately to the Inactive State. When signal power is detected from the LTU (LOS = ZERO), the unit will proceed once again to the Activating State, where another attempt is made at the start-up process. + +For applications outside the scope of this Recommendation, which will use a more sensitive noise margin during the start-up procedure, a more complicated procedure will be necessary, which is nevertheless compatible with the simplified method according to this Recommendation. + +Firstly, the unit can set INDR = ONE even if the defined noise margin is not reached, when it is synchronized and timer T-Act has expired. The purpose of using this condition is straightforward. The units will indicate the receivers are ready for data when they are synchronized and the timers for completing start-up have expired, to allow the units to pass data as best they can, even when normally desired reliability limits are not achieved, in support of applications that can use a less reliable channel and for diagnostics. (The overhead channel contains an indication of the system margin, so that an individual application can determine whether the margin achieved is suitable for its own use or not.) + +Secondly, a parallel way, indicated in Figure 13 by dotted lines, is possible to reach the Active-Tx/Rx State. If the NTU detects INDC = ONE from the LTU before it sets INDR = ONE it will move to the Active-Tx State. In this state its receiver is not ready to receive data, but it begins to transmit 2B1Q data in direction to the LTU, which is ready to receive it. When the NTU sets INDR = ONE it moves from the Active-Tx State to the Active-Tx/Rx State. From the Active-Tx State the only way the NTU can fail to set INDR = ONE is to lose synchronization, but in this case the expiration of timer T-Act forces it to move to the Active-Tx/Rx State anyway and with LOSW = ONE the NTU will move immediately to the Pending Deactivation State. + +#### 5.6.5.2 HDSL transceiver states at the LTU + +Figure 14 shows a state diagram for the activation of the LTU. When powered on, the LTU is initially in the Inactive State, where its transmitter is silent. If the activation request signal ACTREQ is set to ONE, which is normally the default when powering on, the LTU proceeds immediately to the Activating State and executes the timeline shown in Figure 11. + +![Figure 14/G.991.1 – LTU activation state diagram. The diagram shows five states: Inactive State (Tx: Silent), Deactivated State (Tx: Silent), Pending-Deactivation State (Tx: 2B1Q data), Active-Rx State (Tx: S1, Rx: ready), and Active-Tx/Rx State (Tx: 2B1Q data, Rx: 2B1Q data). Transitions are triggered by events like Power On, LOST=1, T-Act expired, LOSWT=1, LOSW=0, LOSW=1, INDC=1, INDR=1, and ACTREQ=1. A dashed circle represents an intermediate state (Active-Tx State) with Tx: 2B1Q data and Rx: not ready.](51d4540605fdfa2c090638305022143b_img.jpg) + +``` + +stateDiagram-v2 + [*] --> Inactive: Power On + Inactive --> Deactivated: LOST = 1 + Inactive --> Activating: ACTREQ = 1 + Activating --> Deactivated: T-Act expired + Activating --> Active-Rx: INDC = 1 + Activating --> Pending-Deactivation: LOSWT = 1 + Active-Rx --> Deactivated: LOSW = 1 + Active-Rx --> Pending-Deactivation: LOSW = 1 + Active-Rx --> Active-Tx/Rx: INDR = 1 or T-Act expired + Pending-Deactivation --> Deactivated: LOSW = 0 + Pending-Deactivation --> Active-Rx: INDR = 1 or T-Act expired + Pending-Deactivation --> Active-Tx/Rx: INDC = 1 or T-Act expired + Active-Tx/Rx --> Pending-Deactivation: LOSW = 1 + Active-Tx/Rx --> Inactive: LOST = 1 + Active-Tx/Rx --> Active-Rx: INDC = 1 + Active-Tx/Rx --> Pending-Deactivation: LOSW = 0 + state "Active-Tx State" as Active-Tx : Tx: 2B1Q data, Rx: not ready + Active-Tx/Rx -.-> Active-Tx : INDC = 1 or T-Act expired + Active-Tx -.-> Active-Rx : INDR = 1 + +``` + +Figure 14/G.991.1 – LTU activation state diagram. The diagram shows five states: Inactive State (Tx: Silent), Deactivated State (Tx: Silent), Pending-Deactivation State (Tx: 2B1Q data), Active-Rx State (Tx: S1, Rx: ready), and Active-Tx/Rx State (Tx: 2B1Q data, Rx: 2B1Q data). Transitions are triggered by events like Power On, LOST=1, T-Act expired, LOSWT=1, LOSW=0, LOSW=1, INDC=1, INDR=1, and ACTREQ=1. A dashed circle represents an intermediate state (Active-Tx State) with Tx: 2B1Q data and Rx: not ready. + +Figure 14/G.991.1 – LTU activation state diagram + +It starts the timer T-Act and the transmission of S0 and monitors the receive line for signal power from the NTU. When it detects signal power it starts timer T1 and restarts timer T-Act. On expiry of T1 it begins to transmit S1 and to wait for the framed four level signal S1 from the NTU to gain synchronization. If synchronization is detected LOSW is set to ZERO. If timer T-Act expires before synchronization is achieved LOSW is set to ONE and the unit moves to the Deactivated State and ceases transmission. The NTU will therefore also be forced to the Deactivated State, as described above, and LOST = ONE will appear after a period of 1 s and the Inactive State will be entered. If ACTREQ is still set to ONE the start-up procedure will be reinitiated. + +When the receiver in the LTU is ready to accept 2B1Q data, it sets the indicator INDC = ONE and moves to the Active-Rx State. The condition for INDC = ONE is, as described in 5.6.2.2.5, that synchronization is reached (LOSW = ZERO), because the noise margin condition is for applications according to this Recommendation met in any case, due to the low value of $-5$ dB defined for the noise threshold. + +When the overhead channel in the transmitted S1 signal becomes available in the preceding start-up procedure, the status INDC = ONE is conveyed to the NTU by setting the indicator bit indc = 0. In the NTU an identical process takes place, as described above, and indr = 0 is received by the LTU in the overhead channel if the NTU has reached its Active-Rx State and is ready to receive 2B1Q data. After reception of six consecutive indicator bit indr = 0 the status indicator INDR is set to ONE and the LTU moves to the Active-Tx/Rx state, where it is fully active, both transmitting and receiving 2B1Q data. + +If it does not detect INDR = ONE before timer T-Act expires, then it will move to the Active-Tx/Rx State anyway where either synchronization is still being maintained or it is not. If the LTU has lost synchronization and LOSW = ONE, the system will proceed to the Pending Deactivation State. On the other hand, if synchronization is present at both ends and the NTU has not failed the timeline and not reached its Deactivated State, the timer at the NTU will promptly force that unit into its Active-Tx/Rx State and set INDR = ONE. When INDR = ONE is detected at the LTU, the system will be operational in the Active-Tx/Rx State. If the NTU does not have synchronization, it will move to its Pending Deactivation State and ultimately to the Deactivated State, where it will go to Silent. At this point the LTU will lose synchronization and move to its own Pending Deactivation State. + +Once in the Active-Tx/Rx State, the unit will remain there unless synchronization is lost or the unit is signalled to go to the QUIET mode or is powered off. If the unit is signalled to go to QUIET mode, it will go to the Deactivated State. If synchronization is lost (LOSW = ONE), the unit will move to the Pending Deactivation State. While in the Pending Deactivation State, the unit attempts to regain synchronization for nominally 2 s. If synchronization is regained in this time (LOSW = ZERO), the unit returns to the Active-Tx/Rx State. If not, LOSWT is set to ONE and the unit enters the Deactivated State. + +After entering the Deactivated State, either due to a period of synchronization word loss (LOSW = ONE) or due to expiration of the timer T-Act, the transmitter in the LTU goes silent and the LTU begins to look for a loss of signal power from the NTU. When a loss of signal (LOS = ONE) is detected for 1 s, LOST is set to ONE and the unit moves immediately to the Inactive State. When ACTREQ is set again to ONE, the unit will proceed once again to the Activating State, where another attempt is made at the start-up process. + +For applications outside the scope of this Recommendation, which will use a more sensitive noise margin during the start-up procedure, a more complicated procedure will be necessary, which is nevertheless compatible with the simplified method according to this Recommendation. + +Firstly, the unit can set INDC = ONE even if the defined noise margin is not reached, when it is synchronized and timer T-Act has expired. The purpose of using this condition is straightforward. The units will indicate that the receivers are ready for data when they are synchronized and the timers for completing start-up have expired, to allow the units to pass data as best they can, even when normally desired reliability limits are not achieved, in support of applications that can use a less reliable channel and for diagnostics. (The overhead channel contains an indication of the system margin, so that an individual application can determine whether the margin achieved is suitable for its own use or not). + +Secondly, a parallel way, indicated in Figure 14 by dotted lines, is possible to reach the Active-Tx/Rx State. If the LTU detects INDR = ONE from the NTU before it sets INDC = ONE it will move to the Active-Tx State. In this state its receiver is not ready to receive data, but it begins to transmit 2B1Q data in direction to the NTU, which is ready to receive it. When the LTU sets INDC = ONE it moves from the Active-Tx State to the Active-Tx/Rx State. From the Active-Tx State the only way the LTU can fail to set INDC = ONE is to lose synchronization, but in this case the expiration of timer T-Act forces it to move to the Active-Tx/Rx State anyway and with LOSW = ONE the LTU will move immediately to the Pending Deactivation State. + +#### 5.6.5.3 The HDSL synchronization state machine + +The HDSL synchronization state machine is shown in Figure 15. When the HDSL transceiver is powered on and is initially detecting S0 signal or when it loses synchronization during one of the Active-Tx/Rx States as shown in Figures 13 and 14, it enters the Out of Sync State. In this state it sets LOSW = ONE and searches for the sync word in the received signal. If it detects the sync word for the first time, it moves to State 0. If the sync word is discovered again in the next frame at the + +correct position, the HDSL transceiver is deemed to be synchronized, the In Sync State is entered and LOSW = ZERO; if not, the HDSL transceiver moves back to the Out of Sync State. + +![Figure 15/G.991.1 – HDSL synchronization state machine diagram. The diagram shows seven states: Out of Sync State (LOSW = 1), State 0, In Sync State (LOSW = 0), State 1, State 2, State 3, State 4, and State 5. Transitions are labeled 'sync' or 'no sync'. From Out of Sync State, a 'sync' transition leads to State 0, and a 'no sync' transition leads to State 5. From State 0, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 5. From In Sync State, a 'sync' transition leads to State 0, and a 'no sync' transition leads to State 1. From State 1, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 2. From State 2, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 3. From State 3, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 4. From State 4, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 5. From State 5, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to Out of Sync State. There is a self-loop on In Sync State labeled 'sync'.](3766b291e69420b0437ae278b057b5ee_img.jpg) + +``` + +stateDiagram-v2 + [*] --> Out_of_Sync_State : Out of Sync State LOSW = 1 + Out_of_Sync_State --> State_0 : sync + Out_of_Sync_State --> State_5 : no sync + State_0 --> In_Sync_State : sync + State_0 --> State_5 : no sync + In_Sync_State --> State_0 : sync + In_Sync_State --> State_1 : no sync + In_Sync_State --> In_Sync_State : sync + State_1 --> In_Sync_State : sync + State_1 --> State_2 : no sync + State_2 --> In_Sync_State : sync + State_2 --> State_3 : no sync + State_3 --> In_Sync_State : sync + State_3 --> State_4 : no sync + State_4 --> In_Sync_State : sync + State_4 --> State_5 : no sync + State_5 --> In_Sync_State : sync + State_5 --> Out_of_Sync_State : no sync + +``` + +Figure 15/G.991.1 – HDSL synchronization state machine diagram. The diagram shows seven states: Out of Sync State (LOSW = 1), State 0, In Sync State (LOSW = 0), State 1, State 2, State 3, State 4, and State 5. Transitions are labeled 'sync' or 'no sync'. From Out of Sync State, a 'sync' transition leads to State 0, and a 'no sync' transition leads to State 5. From State 0, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 5. From In Sync State, a 'sync' transition leads to State 0, and a 'no sync' transition leads to State 1. From State 1, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 2. From State 2, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 3. From State 3, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 4. From State 4, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to State 5. From State 5, a 'sync' transition leads to In Sync State, and a 'no sync' transition leads to Out of Sync State. There is a self-loop on In Sync State labeled 'sync'. + +**Figure 15/G.991.1 – HDSL synchronization state machine** + +To move from the In Sync State to the Out of Sync State the HDSL transceiver has to pass through five intermediate states, named State 1 to State 5. The transition to higher numbered state occurs if the sync word is again not discovered in a succeeding frame. So the sync word has to be lost six times in series before loss of synchronization is deemed and the Out of Sync State is entered. If however in one of the five intermediate states the sync word is discovered, then the HDSL transceiver moves back to the In Sync State immediately. + +### 5.6.6 Regenerator related procedures + +In order to achieve data transmission over distances that are greater than can be achieved by a single HDSL system, a regenerator (REG) is necessary. + +A separate REG shall be provided for each pair. The REG consists of two parts, REG-R for interfacing with the LTU, and REG-C for interfacing with the NTU. An internal connection between the REG-R and REG-C provides the communication between the two parts during start-up and normal operation. + +A connection which uses a regenerator has two separated HDSL links which roughly follow the start-up principles described above for the LTU/NTU start-up procedure. The difference is that the regenerator does not evaluate and insert the indc/indr-bits and also does not perform the path identification procedure based on the Z-bits. + +The link between the LTU and the REG is the first to be activated. After completion of the start-up procedure of this link the second link between the REG and the NTU will be activated. + +The flow diagram of Figure 16 and the regenerator activation state diagram of Figure 17 explain the complete start-up sequences for the link between the LTU and the NTU containing a regenerator. + +![Figure 16/G.991.1 – Flow diagram for start-up with regenerator. This sequence diagram shows the interaction between LTU, DLL, REG-R, REG-C, and NTU. It details the activation process using signals like LOS, ACTREQ, S0, S1, HOH, INDC, INDR, and data transmission. Key states include Inactive, Activating, Active-Rx, and Active-Tx/Rx. Timers T1, T2, T3, and T-Act are shown controlling transitions.](7e14467740b2570a44379b347a697921_img.jpg) + +``` + +sequenceDiagram + participant LTU + participant DLL1 as DLL + participant REGR as REG-R + participant REGC as REG-C + participant DLL2 as DLL + participant NTU + + Note over LTU, NTU: Inactive / Silent + LTU->>DLL1: ACTREQ 0 -> 1 + LTU->>DLL1: S0 + DLL1->>REGR: S0 + REGR->>REGC: LOS-R = 0 + REGR->>DLL1: S0 + DLL1->>LTU: S0 + Note over LTU: Activating (Note 5) + LTU->>DLL1: S1 + DLL1->>REGR: S1 + REGR->>DLL1: HOH-R hrp + DLL1->>LTU: HOH-R hrp (Note 1) + REGC->>DLL2: ACTREQ 0 -> 1 + REGC->>DLL2: S0 + DLL2->>NTU: S0 + Note over NTU: Activating + NTU->>DLL2: S0 + DLL2->>REGC: S0 + Note over REGC: Activating-C (Note 5) + REGC->>DLL2: S1 + DLL2->>NTU: S1 + NTU->>DLL2: HOH-C + DLL2->>REGC: HOH-C + Note over NTU: Active-Rx + NTU->>DLL2: INDR + DLL2->>REGC: INDR + REGC->>REGR: HOH + REGR->>DLL1: indc + DLL1->>LTU: INDC + Note over LTU: Active-Rx + LTU->>DLL1: HOH + DLL1->>REGR: indr + REGR->>REGC: HOH + REGC->>DLL2: indc + DLL2->>NTU: INDC (Note 2) + Note over NTU: Active-Tx/Rx + NTU->>DLL2: data + DLL2->>REGC: data + REGC->>REGR: data + REGR->>DLL1: data + DLL1->>LTU: data + Note over LTU: Active-Tx/Rx + +``` + +Figure 16/G.991.1 – Flow diagram for start-up with regenerator. This sequence diagram shows the interaction between LTU, DLL, REG-R, REG-C, and NTU. It details the activation process using signals like LOS, ACTREQ, S0, S1, HOH, INDC, INDR, and data transmission. Key states include Inactive, Activating, Active-Rx, and Active-Tx/Rx. Timers T1, T2, T3, and T-Act are shown controlling transitions. + +T1528970-98 + +--- + + new state + +NOTE 1 – After having detected the status indicator INDC, the LTU starts to evaluate the indr- and hrp-bit. If an hrp-bit set to ONE is received no regenerator is present. + +NOTE 2 – If the indc = 0 has been received six times consecutively, the NTU becomes transparent for payload blocks. + +NOTE 3 – If the indr = 0 has been received six times consecutively, the LTU becomes transparent for payload blocks. + +NOTE 4 – Transceivers provide an all-ONE signal in the payload block and HOH to the succeeding circuitry as long as their receivers have not entered the active state. + +NOTE 5 – Timer T-Act is restarted after reception of S0 from the NTU, or REG-R, respectively. + +NOTE 6 – Timer T4 is an NTU/REG internal timer and is therefore not shown in this diagram. + +NOTE 7 – HOH indicates that all HOH-bits are active, while HOH-R and HOH-C indicate that only those HOH-bits are active, which are originated by the REG-R or REG-C respectively, all others are set to ONE. + +**Figure 16/G.991.1 – Flow diagram for start-up with regenerator** + +**Recommendation G.991.1 (10/98)** + +![Figure 17/G.991.1 – REG activation state diagram](feae5a5b6e128162dbced0860fd97b9b_img.jpg) + +``` + +graph TD + PowerOn((Power on)) --> InactiveR + PowerOn --> InactiveC + + subgraph REG-R + InactiveR((Inactive-R State
Tx: Silent)) -- "LOS-R 1 → 0" --> ActivatingR + ActivatingR((Activating-R State
Tx: Silent, S0 or S1)) -- "T-Act-R expired" --> DeactivatedR + ActivatingR -- "LOSW-R 1 → 0" --> ActiveR + DeactivatedR((Deactivated-R State
Tx: Silent)) -- "LOS-R = 1" --> InactiveR + ActiveR((Active-R State
Tx, Rx: 2B1Q data)) -- "LOSW-R = 1" --> PendingDeactivationR + PendingDeactivationR((Pending Deactivation-R State
Tx: 2B1Q data)) -- "LOSW-R = 0" --> ActiveR + PendingDeactivationR -- "LOSWT-R = 1" --> DeactivatedR + end + + subgraph REG-C + InactiveC((Inactive-C State
Tx: Silent)) -- "Actreq-C 0 → 1" --> ActivatingC + ActivatingC((Activating-C State
Tx: S0 or S1)) -- "T-Act-C expired" --> DeactivatedC + ActivatingC -- "LOSW-C1 → 0" --> ActiveC + DeactivatedC((Deactivated-C State
Tx: Silent)) -- "LOST-C = 1" --> InactiveC + ActiveC((Active-C State
Tx, Rx: 2B1Q data)) -- "LOSW-C = 1" --> PendingDeactivationC + PendingDeactivationC((Pending Deactivation-C State
Tx: 2B1Q data)) -- "LOSW-C = 0" --> ActiveC + PendingDeactivationC -- "LOSWT-C = 1" --> DeactivatedC + end + + %% Cross-dependencies + DeactivatedR -- "REG-C enters the deactivated state (Note 2)" --> DeactivatedR + DeactivatedC -- "REG-R enters the deactivated state (Note 1)" --> DeactivatedC + ActiveR -. "(Note 3)" .- ActiveC + +``` + +The diagram illustrates the state transitions for REG-R and REG-C. REG-R states include Inactive-R, Activating-R, Deactivated-R, Active-R, and Pending Deactivation-R. REG-C states include Inactive-C, Activating-C, Deactivated-C, Active-C, and Pending Deactivation-C. Transitions are triggered by signal status changes (LOS, LOSW) or timers (T-Act). Notes indicate inter-dependencies between the R and C sides. + +Figure 17/G.991.1 – REG activation state diagram + +NOTE 1 – The REG-R entering the Deactivated-R State forces the REG-C to enter the Deactivated-C State, if the REG-C is in one of the states Activating-C, Active-C or Pending Deactivation-C. +NOTE 2 – The REG-C entering the Deactivated-C State forces the REG-R to enter the Deactivated-R State, if the REG-R is in one of the states Activating-R, Active-R or Pending Deactivation-R. +NOTE 3 – As long as the REG-C transceiver has not entered the Active-C State, only REG specific overhead bits are transmitted to the LTU. All other transmitted bits are ONE. + +**Figure 17/G.991.1 – REG activation state diagram** + +53 + +#### 5.6.6.1 Activation state diagrams for the REG + +The activation procedures with regenerators follow the same principles as described for the LTU and NTU only. As the indc/indr-bits reflect the status of the LTU- and NTU-receiver only, the evaluation and insertion of these bits in the REG, however, are not necessary. This results in a less complex state diagram for the REG-C and REG-R side in the REG as shown in Figure 17. When the system is powered on, the REG-C as well as the REG-R enters its Inactive State, after completing self-tests. + +##### 5.6.6.1.1 HDSL transceiver states at the REG-R + +During the Inactive-R State the HDSL transceiver at the REG-R is silent, LOSW-R = ONE and LOS-R = ONE. Upon the detection of a signal from the HDSL transceiver at the LTU (LOS-R = ZERO) it changes to the Activating-R State and follows the timeline shown in Figure 11 for the NTU. + +It waits T2 = 2 s while transmitting no signal then starts the timer T-Act and the transmission of S0 and monitors the received signal for S1. When the REG-R detects a valid framed four level data signal from the LTU it sets LOSW-R = ZERO, starts timer T3 and proceeds to the Active-R State. If the synchronization fails, this means if T-Act expires before LOSW-R = ZERO, the REG-R moves to the Deactivated-R State, ceases transmission and forces REG-C into the Deactivated-C State. The further behaviour is described below. + +On expiry of T3 the REG-R begins to transmit S1 signal. + +Upon entering the Active-R State the T-Act timer is deactivated and an activation request signal ACTREQ = ONE is sent to the REG-C. In this state the receiver is fully synchronized and in the direction REG → LTU, the REG-specific overhead bits (eoc, rrbe, rega, hrp, crc) are active, all other overhead bits, as well as the payload data, are transferred transparently. This finally results in transparent transmission of both the overhead bits and the payload data in the REG-R in the directions REG-R → REG-C and REG-R → LTU, except the REG specific overhead bits which are handled as described in 5.7. + +If the REG-R loses synchronization (LOSW-R = ONE) it starts a 2 s timer and moves to the Pending Deactivation-R State, where the signal as received from the REG-C transceiver is transmitted. If the synchronization is regained before the 2 s timer expires, then LOSW-R is set to ZERO and the HDSL transceiver at the REG-R returns to the Active-R State. If however the 2 s timer expires, then LOSWT-R is set to ONE and the HDSL transceiver at the REG-R changes to the Deactivated-R State. + +During the Deactivated-R State, the HDSL transceiver at the REG-R is silent and looks for signal power from the HDSL transceiver at the LTU. When no power is detected (LOS-R = ONE) it changes to the Inactive State. Entering the Deactivated-R State results in forcing the REG-C to the Deactivated-C state, if the REG-C is in one of the states Activating-C, Active-C or Pending Deactivation-C. + +##### 5.6.6.1.2 HDSL transceiver states at the REG-C + +During the Inactive-C State the HDSL transceiver at the REG-C is silent and LOSW-C = ONE. If the ACTREQ = ONE command from the REG-R transceiver indicates that the REG-R has entered the Active-R state it moves to the Activating-C State and follows the timeline shown in Figure 11 for the LTU. + +When the HDSL transceiver at the REG-C enters this state from the Inactive-C State, it starts timer T-Act and transmission of the S0 signal. During the transmission of the S0 signal, when it detects signal power from the HDSL transceiver at the NTU it starts timer T1 and restarts timer T-Act. + +When the T1 timer expires the HDSL transceiver at the REG-C starts to transmit the S1 signal. The data transmitted in the payload and the overhead bits during the Activating-C State are ONE, in both directions REG-C → NTU and REG-C → REG-R. During the transmission of the S1 signal it waits for the framed S1 signal to gain synchronization. If the HDSL frame synchronization is detected then LOSW-C = ZERO and the REG-C enters the Active-C State and deactivates the timer T-Act. If the T-Act timer expires before LOSW-C becomes ZERO, the HDSL transceiver at the REG-C changes to the Deactivated-C State, ceases transmission and forces the REG-R into the Deactivated-R State. The further behaviour is as described below. + +During the Active-C State both the overhead and payload data are transmitted transparently in both directions REG-C → NTU and REG-C → REG-R except the regenerator specific overhead bits, which are handled inside the REG. If the HDSL frame synchronization is lost LOSW-C is set to ONE and the HDSL transceiver at the REG-C changes to the Pending Deactivated-C State and a 2 s timer is started. + +During the Pending Deactivation-C State the signal transmitted is the same as received from REG-R. If synchronization is regained then LOSW-C is set to ZERO and the HDSL transceiver at the REG-C returns to the Active-C State. If the 2 s timer expires without synchronization, then LOSWT-C is set to ONE and the HDSL transceiver at the REG-C changes to the Deactivated-C State. + +During the Deactivated-C State, the HDSL transceiver at the REG-C is silent and looks for signal power from the HDSL transceiver at the NTU. Entering the Deactivated-C State results in forcing the REG-R to the Deactivated-R State. When no power is detected (LOS-C = ONE) a 1 s timer is started and after this timer expires (LOST-C = ONE) the HDSL transceiver at the REG-C changes to the Inactive-C State. + +## 5.7 Operation and maintenance + +This subclause deals with operation and maintenance for transmission systems using HDSL technique. The OAM aspects for such systems are separated between the OAM functions of the HDSL core and those supported by the applications. + +The following subclauses are divided with respect to the applications supported. Commands and responses of the system can either be transmitted through the application interfaces or via external OAM interfaces at maintenance reference points at the NTU and LTU as appropriate. Only the functionality of these OAM reference points will be specified in this Recommendation. + +The support of partial operation in a failure situation and of fractional installation shall be possible as an option. + +### 5.7.1 Functions at the LTU external OAM reference point + +These OAM functions requested by an external OAM entity, are originated within the OAM functional block (maintenance) at the LTU. The network elements addressed by these commands are identified in Table 14. + +**Table 14/G.991.1 – Control functions at the external OAM interface** + +| Function | HDSL transceiver pair | Addressed network element
(Note 2) | +|--------------------------------------------------------------|------------------------------|-----------------------------------------------| +| Loopback control | All | LTU/REG | +| Loopback control of application frame | Note 5 | NTU (Note 3) | +| Start-up control | All | LTU | +| Reset control | All | LTU/NTU/REG | +| CRC error reporting on each pair | All | LTU/NTU/REG (Note 1) | +| Set corrupted CRC on each pair | All | LTU/NTU/REG | +| Response from each pair for corrupted CRC | All | LTU/NTU/REG | +| Request for transmission quality on each pair
(Note 7) | All | LTU/NTU/REG | +| Response for transmission quality from each pair
(Note 7) | All | LTU/NTU/REG | +| Set configuration | Note 5 | LTU/NTU (interface block) | +| Read configuration | Note 5 | LTU/NTU (interface block) | +| Status report | Note 6 | LTU/NTU/REG | +| Excessive error ratio on each pair | All | LTU/NTU/REG (interface block) (Note 4) | +| Identification of equipment | Note 5 | LTU/NTU/REG | +| Other failure indications | All | LTU/NTU/REG | + +NOTE 1 – The calculation of these parameters is based on the CRC-6 procedure inside each subsystem. +NOTE 2 – The use of a regenerator is optional. +NOTE 3 – The location of the loopback of the application frame shall be as near as possible to the application interface. The loopback shall be complete. +NOTE 4 – The excessive error rate indication may be set if 150 errored frames out of 166 frames (1 s) are detected. +NOTE 5 – This function is transported transparently through the HDSL core. This Note is not relevant if a regenerator is addressed. +NOTE 6 – The status report of network elements within the access digital section shall reflect the status of the HDSL core and the application. +NOTE 7 – Transmission quality is represented by noise margin as defined in 5.5.7 or by signal quality as defined in Annex B. + +### **5.7.2 Functions at the NTU external OAM reference point** + +The NTU external OAM reference point may be implemented as an option and is not completely specified in this Recommendation. + +Only the use of visible indications towards the customer are dealt with. The use of a data interface for reporting to/from the customer is not foreseen. Access to the operators TMN system via this reference point shall not be possible. + +Examples of reporting towards the customer at the NTU may be: + +- indication of power; +- indication of severe failures; +- indication of testing from the network side. + +### 5.7.3 OAM messages and functions supported by the HDSL core + +In this subclause, messages are described which are conveyed inside the HDSL frame for OAM purposes. In addition OAM functions are defined which have to be located inside the HDSL core. These messages and functions are listed in Table 15. + +**Table 15/G.991.1 – OAM messages and functions supported by the HDSL core** + +| Messages/functions | OAM core | Local | Core related function | Available on each pair | HOH- bit [additional OH-bits in payload] | eoc-message | Addressed element | | | +|-----------------------------------------------------------------|----------|-------|-----------------------|------------------------|------------------------------------------|-------------|-------------------|-------|-------| +| | | | | | | | L T U | R E G | N T U | +| Reset control | → | * | y | n | | | * | | | +| Start-up control | → | * | y | n | | | * | | | +| Pair identification detection | ← | * | y | y | | | * | | * | +| Loopback control for LTU line side | → | * | y | n | | | * | | | +| Loopback control for REG | → | | y | n | | * | | * | | +| Loopback control for application frame | → | | n | n | | * | | | * | +| CRC error detected at LTU | ← | * | y | y | | | * | | | +| CRC error detected at REG-R | ← | | y | y | rrbe | | | * | | +| CRC error detected at REG-C | ← | | y | y | rcbe | | | * | | +| CRC error detected at NTU | ← | | y | y | febe | | | | * | +| Corrupted CRC at LTU | → | * | y | y | | | * | | | +| Corrupted CRC at REG-R | → | | y | y | | * | | * | | +| Corrupted CRC at REG-C | → | | y | y | | * | | * | | +| Corrupted CRC at NTU | → | | y | y | | * | | | * | +| LOS/LFA at LTU line side (Note 1) | ← | * | y | y | | | * | | | +| LOS/LFA at REG-R (Note 1) | ← | | y | y | | | | * | | +| LOS/LFA at REG-C (Note 1) | ← | | y | y | | | | * | | +| LOS/LFA at line side of NTU (Note 1) | ← | | y | y | | | | | * | +| Pair identification for two-pair systems and three-pair systems | → | | y | y | [Z11 .. Z33]
[Z11 .. Z22] | | * | | | +| Request transmission quality LTU | → | * | y | y | | | * | | | + +**Table 15/G.991.1 – OAM messages and functions supported by the HDSL core (continued)** + +| Messages/functions | OAM core | Local | Core related function | Available on each pair | HOH- bit [additional OH-bits in payload] | eoc-message | Addressed element | | | +|------------------------------------------------------|----------|-------|-----------------------|------------------------|------------------------------------------|-------------|-------------------|-------------|-------------| +| | | | | | | | L
T
U | R
E
G | N
T
U | +| Request transmission quality REG-R (REG-C) | → | | y | y | | * | | * | | +| Request transmission quality NTU | → | | y | y | | * | | | * | +| Transmission quality LTU | ← | * | y | y | | | * | | | +| Transmission quality REG-R (REG-C) | ← | | y | y | | * | | * | | +| Transmission quality NTU | ← | | y | y | | * | | | * | +| Request status REG | → | | y | y | | * | | * | | +| Request status NTU | → | | y | n | | * | | | * | +| REG status (Note 2) | ← | | y | y | | * | | * | | +| NTU status (Note 2) | ← | | y | n | | * | | | * | +| Read NTU configuration (Note 3) | → | | n | n | | * | | | * | +| Write NTU configuration (Note 3) | → | | n | n | | * | | | * | +| NTU configuration | ← | | n | n | | * | | | * | +| Request equipment identification REG | → | | y | y | | * | | * | | +| Request equipment identification NTU | → | | n | n | | * | | | * | +| Equipment identification REG | ← | | n | y | | * | | * | | +| Equipment identification NTU | ← | | n | n | | * | | | * | +| Internal alarm in NTU (Note 4) | ← | | y | n | rta | | | | * | +| Internal alarm in REG (Note 4) | ← | | y | y | rega | | | * | | +| LOS at the application interface of the LTU (Note 5) | → | | n | n | losd (LTU → NTU) | | * | | | +| LOS at the application interface of the NTU (Note 5) | ← | | n | n | losd (NTU → LTU) | | | | * | + +**Table 15/G.991.1 – OAM messages and functions supported by the HDSL core (concluded)** + +| Messages/functions | OAM core | Local | Core related function | Available on each pair | HOH- bit [additional OH-bits in payload] | eoc-message | Addressed element | | | +|--------------------------------------------------------------------|----------|-------|-----------------------|------------------------|------------------------------------------|-------------|-------------------|-------------|-------------| +| | | | | | | | L
T
U | R
E
G | N
T
U | +| Bipolar violation at the application interface of the LTU (Note 6) | → | | n | n | bpv (LTU → NTU) | | * | | | +| Bipolar violation at the application interface of the NTU (Note 6) | ← | | n | n | bpv (NTU → LTU) | | | | * | + +NOTE 1 – LOS or LFA at the line side of the LTU, NTU or REG leads to a deactivation of the respective path after 2 s and therefore always results in an LOS message from the HDSL core to the OAM functional block in the LTU. The LTU OAM unit cannot determine however the location of the fault. + +NOTE 2 – The status register contains single bits representing the current status of the equipment. This information can be used to get detailed information, e.g. after receiving internal alarm bits rta or rega. + +NOTE 3 – The configuration register of the NTU contains dedicated bits which allow for remote configuration of the equipment by the LTU. Examples are transparent/non transparent mode, masking of alarms, equipment behaviour during fault conditions (e.g. transmitting of AIS). + +NOTE 4 – The internal alarm bits are used for signalling equipment internal failure conditions, which are not covered by separate indicator bits. Possible events are: + +- Loss of internal clock sources +- Max delay difference between pairs exceeded +- ROM/RAM test negative + +NOTE 5 – The use of this function is application dependent. + +NOTE 6 – The general need for this function has not been identified. It is left to the network operators to request this functions for particular applications. + +### 5.7.4 Power feeding related OAM functions + +**Table 16/G.991.1 – Power feeding related functions** + +| Function | OAM P | Local | HOH-bits | eoc-messages | Location | | +|----------------------------|-------|-------|----------|--------------|----------|------------| +| | | | | | LTU | REG
NTU | +| NTU power source 1 failure | ← | | ps1 | | | | +| NTU power source 2 failure | ← | | ps2 | | | | + +### 5.7.5 Regenerator behaviour + +#### 5.7.5.1 Response to LOS/LFA + +A regenerator shall respond to LOS/LFA. When LOS/LFA is recognized the behaviour of the REG shall be as follows: + +Both sides of the REG shall be deactivated autonomously by the REG when LOS/LFA is detected on any HDSL line interface. The conditions for detecting LOS/LFA are described in 5.6. + +NOTE – This will finally result in deactivation of the subsystem after detection of LOS/LFA anywhere in the subsystem and both LTU and NTU will identify LOS/LFA for this subsystem. The LOS/LFA detection is a function of the individual HDSL transceivers. + +#### **5.7.5.2 Operation of loopback 1A** + +The activation of loopback 1A in any subsystem of the transceiver is initiated by the LTU by the appropriate eoc-message as described in 5.5. The loopback request may be started simultaneously with the beginning of the start-up procedure or during an already active HDSL link. + +In the first case, the loopback request may be transmitted toward the REG as soon as signal S1 according to 5.6 is transmitted in the direction LTU → NTU. After the eoc-message has been detected in the REG the loopback is closed accordingly. + +In the second case of an already active link, the control unit in the REG closes the loop as soon as the eoc-message has been detected. The detailed procedure of reaching the synchronous loopback state is up to the vendor. (It may be necessary to reset the REG-C transceiver, so that its equalizer and echo canceller coefficients may converge under the loopback conditions). + +A successfully closed loopback may be detected in the LTU by evaluating the valid received Z-bits used for path identification. The loopback is transparent, i.e. the looped back signal is also transmitted toward the NTU. + +During an active loopback 1A the operation of the HDSL overhead bits shall be as follows: + +- The eoc channel is not looped back but is fully operating between the LTU and the REG as described in 5.5 as long as the messages sent by the LTU contain the REG address "10". When detecting any other address the REG inserts the "Hold State" message with its own address in the direction REG → LTU. +- All indicator bits, except the REG specific bits hrp, rega, rrbe and rcbe which are operating normally, are looped back. + +To deactivate loopback 1A the LTU transmits the "Return to Normal" message together with the address "10" in the eoc channel. After detecting this message the REG control unit deactivates autonomously the REG-C transceiver and cancels the loopback operation. + +If the HDSL link between the LTU and the REG is still active the REG control unit immediately starts to activate the link between the REG and the NTU, as described in 5.6. The successful completion of the start-up procedure may be detected by the LTU by evaluating the Z-bits used for path identification. + +## **5.8 Electrical characteristics of a single 2B1Q transceiver** + +### **5.8.1 General** + +This subclause describes the electrical characteristics of a single HDSL transceiver. + +The electrical characteristics of a HDSL transceiver shall be such as to enable the performance requirements of appropriate applications (for which examples are listed in Appendix I) to be met. In addition, the following specific electrical characteristics are required. + +Means should be provided in order to enable the testing of the electrical characteristics of a single 2B1Q transceiver. + +### **5.8.2 Transmitter/receiver impedance and return loss** + +The nominal driving point impedance at the line side of an HDSL transceiver shall be 135 ohms. + +The minimum return loss with respect to 135 ohms over a frequency band of 1 kHz to 1 MHz shall be: + +- 16 dB from 40 kHz to 196 kHz as shown in Figure 18 for 392 kbaud systems; + - 16 dB from 40 kHz to 292 kHz as shown in Figure 19 for 584 kbaud systems; and + - 16 dB from 80 kHz to 485 kHz as shown in Figure 20 for 1160 kbaud systems; +- with a slope of 20 dB/decade below respectively above these frequencies. + +![Figure 18: Minimum return loss of a 392 kbaud system. The graph shows return loss in dB on the y-axis (0 to 20) against frequency in Hz on a logarithmic x-axis (10^3 to 10^7). The curve is 0 dB from 10^3 Hz to 40 kHz, rises with a 20 dB/decade slope to 16 dB at 40 kHz, stays at 16 dB until 196 kHz, falls with a 20 dB/decade slope to 0 dB at 1 MHz, and remains at 0 dB up to 10^7 Hz.](5a31f8496931f6aa7570270dbeefca1e_img.jpg) + +Figure 18 is a graph showing the minimum return loss (in dB) versus frequency (in Hz) for a 392 kbaud system. The y-axis represents return loss in dB, ranging from 0 to 20. The x-axis represents frequency in Hz, ranging from $10^3$ to $10^7$ . The curve shows a flat 0 dB region from $10^3$ Hz to 40 kHz, a 20 dB/decade slope rising to 16 dB at 40 kHz, a flat 16 dB region until 196 kHz, a 20 dB/decade slope falling to 0 dB at 1 MHz, and a flat 0 dB region from 1 MHz to $10^7$ Hz. + +Figure 18: Minimum return loss of a 392 kbaud system. The graph shows return loss in dB on the y-axis (0 to 20) against frequency in Hz on a logarithmic x-axis (10^3 to 10^7). The curve is 0 dB from 10^3 Hz to 40 kHz, rises with a 20 dB/decade slope to 16 dB at 40 kHz, stays at 16 dB until 196 kHz, falls with a 20 dB/decade slope to 0 dB at 1 MHz, and remains at 0 dB up to 10^7 Hz. + +**Figure 18/G.991.1 – Minimum return loss of a 392 kbaud system** + +![Figure 19: Minimum return loss of a 584 kbaud system. The graph shows return loss in dB on the y-axis (0 to 20) against frequency in Hz on a logarithmic x-axis (10^3 to 10^7). The curve is 0 dB from 10^3 Hz to 40 kHz, rises with a 20 dB/decade slope to 16 dB at 40 kHz, stays at 16 dB until 292 kHz, falls with a 20 dB/decade slope to 0 dB at 1 MHz, and remains at 0 dB up to 10^7 Hz.](03e25a69b2145b8a280edf2421fbc07f_img.jpg) + +Figure 19 is a graph showing the minimum return loss (in dB) versus frequency (in Hz) for a 584 kbaud system. The y-axis represents return loss in dB, ranging from 0 to 20. The x-axis represents frequency in Hz, ranging from $10^3$ to $10^7$ . The curve shows a flat 0 dB region from $10^3$ Hz to 40 kHz, a 20 dB/decade slope rising to 16 dB at 40 kHz, a flat 16 dB region until 292 kHz, a 20 dB/decade slope falling to 0 dB at 1 MHz, and a flat 0 dB region from 1 MHz to $10^7$ Hz. + +Figure 19: Minimum return loss of a 584 kbaud system. The graph shows return loss in dB on the y-axis (0 to 20) against frequency in Hz on a logarithmic x-axis (10^3 to 10^7). The curve is 0 dB from 10^3 Hz to 40 kHz, rises with a 20 dB/decade slope to 16 dB at 40 kHz, stays at 16 dB until 292 kHz, falls with a 20 dB/decade slope to 0 dB at 1 MHz, and remains at 0 dB up to 10^7 Hz. + +**Figure 19/G.991.1 – Minimum return loss of a 584 kbaud system** + +![Figure 20/G.991.1 – Minimum return loss of a 1160 kbaud system. The graph shows return loss in dB on the y-axis (0 to 20) against frequency in Hz on a logarithmic x-axis (10^3 to 10^7). The curve is flat at 0 dB from 10^3 Hz to approximately 1.16 x 10^6 Hz. It then rises with a 20 dB/dec slope to 16 dB at 8 x 10^6 Hz, remains flat at 16 dB until 4.85 x 10^6 Hz, and then falls with a 20 dB/dec slope back to 0 dB at approximately 10^7 Hz.](de7b700c44b3911907685dffd54fc50f_img.jpg) + +Figure 20/G.991.1 – Minimum return loss of a 1160 kbaud system. The graph shows return loss in dB on the y-axis (0 to 20) against frequency in Hz on a logarithmic x-axis (10^3 to 10^7). The curve is flat at 0 dB from 10^3 Hz to approximately 1.16 x 10^6 Hz. It then rises with a 20 dB/dec slope to 16 dB at 8 x 10^6 Hz, remains flat at 16 dB until 4.85 x 10^6 Hz, and then falls with a 20 dB/dec slope back to 0 dB at approximately 10^7 Hz. + +**Figure 20/G.991.1 – Minimum return loss of a 1160 kbaud system** + +### 5.8.3 Transceiver reference clock + +The reference clock shall be: + +- for one-pair 2320 kHz $\pm$ 32 ppm; +- for two-pair 1168 kHz $\pm$ 32 ppm; +- for three-pair 784 kHz $\pm$ 32 ppm. + +### 5.8.4 Transmitter output characteristics + +Unless otherwise indicated, the following specification applies with a resistive load impedance corresponding to the nominal. + +#### 5.8.4.1 Pulse amplitude + +The nominal peak of the largest pulse shall be 2.64 V for the three- and two-pair system and 2.50 V for the one-pair system. + +#### 5.8.4.2 Pulse shape + +The transmitted pulse shall have the shape specified in Figure 21 for the three- and two-pair system and in Figure 22 for the one-pair system. + +The pulse mask for the four quaternary symbols shall be obtained by multiplying the normalized pulse mask shown in Figure 21 by 2.64 V, 0.88 V, –0.88 V or –2.64 V and in Figure 22 by 2.50 V, 0.833 V, –0.833 V and –2.50 V. + +![Figure 21/G.991.1: Transmit pulse for two- and three-pair systems; normalized pulse mask. The diagram shows a pulse shape with various levels labeled A through H. A table to the right provides the voltage values for these levels across four quaternary symbols (+3, +1, -1, -3).](b91520013ba00f460455724c767a470d_img.jpg) + +Normalized pulse mask for two- and three-pair systems. The pulse shape is defined by the following levels and time points: + +- Time points: $-0.6 T$ , $-0.4 T$ , $0$ , $0.4 T$ , $0.5 T$ , $T$ , $1.25 T$ , $1.4 T$ , $14 T$ , $50 T$ . +- Levels: $A = 0.01$ , $F = -0.01$ , $B = 1.07$ , $C = 1.00$ , $D = 0.93$ , $E = 0.03$ , $H = -0.05$ , $G = -0.16$ . + +| Normalized level | Quaternary symbols | | | | | +|------------------|--------------------|-----------|-----------|-----------|-----------| +| | +3 | +1 | -1 | -3 | | +| A | 0.01 | 0.0264 V | 0.0088 V | -0.0088 V | -0.0264 V | +| B | 1.07 | 2.8248 V | 0.9416 V | -0.9416 V | -2.8248 V | +| C | 1.00 | 2.6400 V | 0.8800 V | -0.8800 V | -2.6400 V | +| D | 0.93 | 2.4552 V | 0.8184 V | -0.8184 V | -2.4552 V | +| E | 0.03 | 0.0792 V | 0.0264 V | -0.0264 V | -0.0792 V | +| F | -0.01 | -0.0264 V | -0.0088 V | 0.0088 V | 0.0264 V | +| G | -0.16 | -0.4224 V | -0.1408 V | 0.1408 V | 0.4224 V | +| H | -0.05 | -0.1320 V | -0.0440 V | 0.0440 V | 0.1320 V | + +$T = 2.55 \mu\text{s}$ at 784 kbit/s + $T = 1.71 \mu\text{s}$ at 1168 kbit/s + +Figure 21/G.991.1: Transmit pulse for two- and three-pair systems; normalized pulse mask. The diagram shows a pulse shape with various levels labeled A through H. A table to the right provides the voltage values for these levels across four quaternary symbols (+3, +1, -1, -3). + +Figure 21/G.991.1 – Transmit pulse for two- and three-pair systems; normalized pulse mask + +![Figure 22/G.991.1: Transmit pulse for a one-pair system; normalized pulse mask. The diagram shows a pulse shape with various levels labeled A through H. A table to the right provides the voltage values for these levels across four quaternary symbols (+3, +1, -1, -3).](a4cabfec798f5330bf8cc750d4d518ee_img.jpg) + +Normalized pulse mask for a one-pair system. The pulse shape is defined by the following levels and time points: + +- Time points: $-0.6 T$ , $-0.4 T$ , $0$ , $0.4 T$ , $0.5 T$ , $T$ , $1.25 T$ , $1.4 T$ , $14 T$ , $50 T$ . +- Levels: $A = 0.01$ , $F = -0.01$ , $B = 1.07$ , $C = 1.00$ , $D = 0.93$ , $E = 0.04$ , $H = -0.05$ , $G = -0.20$ . + +| Normalized level | Quaternary symbols | | | | | +|------------------|--------------------|-----------|-----------|-----------|-----------| +| | +3 | +1 | -1 | -3 | | +| A | 0.01 | 0.0250 V | 0.0083 V | -0.0083 V | -0.0250 V | +| B | 1.07 | 2.6750 V | 0.8917 V | -0.8917 V | -2.6750 V | +| C | 1.00 | 2.5000 V | 0.8333 V | -0.8333 V | -2.5000 V | +| D | 0.93 | 2.3250 V | 0.7750 V | -0.7750 V | -2.3250 V | +| E | 0.04 | 0.1000 V | 0.0333 V | -0.0333 V | -0.1000 V | +| F | -0.01 | -0.0250 V | -0.0083 V | 0.0083 V | 0.0250 V | +| G | -0.20 | -0.5000 V | -0.1667 V | 0.1667 V | 0.5000 V | +| H | -0.05 | -0.1250 V | -0.0417 V | 0.0417 V | 0.1250 V | + +$T = 0.862 \mu\text{s}$ at 2320 kbit/s + +Figure 22/G.991.1: Transmit pulse for a one-pair system; normalized pulse mask. The diagram shows a pulse shape with various levels labeled A through H. A table to the right provides the voltage values for these levels across four quaternary symbols (+3, +1, -1, -3). + +Figure 22/G.991.1 – Transmit pulse for a one-pair system; normalized pulse mask + +### 5.8.4.3 Power spectral density + +#### 5.8.4.3.1 Power spectral density for 392 kbaud systems + +The upper bound of the average power spectral density of the signal transmitted by the HDSL transmitter shall be as shown in Figure 23. + +- $-37$ dBm/Hz from 0 Hz to 196 kHz; +- $-80$ dB/decade fall from $-37$ dBm/Hz at 196 kHz to $-117$ dBm/Hz at 1.96 MHz; +- $-117$ dBm/Hz above 1.96 MHz. + +![Figure 23/G.991.1: Upper bound of the average power spectral density of a 392 kbaud system. The graph shows power spectral density in dBm/Hz on the y-axis (from -120 to -20) versus frequency in Hz on a logarithmic x-axis (from 10^3 to 4x10^6). The curve is flat at -37 dBm/Hz from 10^3 Hz to 1.96x10^5 Hz, then falls with a slope of -80 dB/decade to -117 dBm/Hz at 1.96x10^6 Hz, and remains flat at -117 dBm/Hz up to 4x10^6 Hz. A horizontal line at -117 dBm/Hz is labeled 'Floor at -117 dBm/Hz'.](47e01b9fff5e98218a11fa5958b988fb_img.jpg) + +The figure is a line graph on a semi-logarithmic scale. The y-axis is labeled 'dBm/Hz' and ranges from -120 to -20 in increments of 20. The x-axis is labeled 'Hz' and has major ticks at $10^3$ , $10^4$ , $10^5$ , $1.96 \times 10^5$ , $10^6$ , $1.96 \times 10^6$ , and $4 \times 10^6$ . The graph shows a piecewise linear function. It starts at $-37$ dBm/Hz at $10^3$ Hz and remains constant until $1.96 \times 10^5$ Hz. At this point, it begins a downward slope. At $10^6$ Hz, the power density is $-87$ dBm/Hz. At $1.96 \times 10^6$ Hz, it reaches $-117$ dBm/Hz. From $1.96 \times 10^6$ Hz to $4 \times 10^6$ Hz, the power density remains constant at $-117$ dBm/Hz. A horizontal line at $-117$ dBm/Hz is labeled 'Floor at $-117$ dBm/Hz'. The label ' $-37$ dBm/Hz' is placed above the first horizontal segment. A small code 'T1529040-98' is in the bottom right corner. + +Figure 23/G.991.1: Upper bound of the average power spectral density of a 392 kbaud system. The graph shows power spectral density in dBm/Hz on the y-axis (from -120 to -20) versus frequency in Hz on a logarithmic x-axis (from 10^3 to 4x10^6). The curve is flat at -37 dBm/Hz from 10^3 Hz to 1.96x10^5 Hz, then falls with a slope of -80 dB/decade to -117 dBm/Hz at 1.96x10^6 Hz, and remains flat at -117 dBm/Hz up to 4x10^6 Hz. A horizontal line at -117 dBm/Hz is labeled 'Floor at -117 dBm/Hz'. + +Figure 23/G.991.1 – Upper bound of the average power spectral density of a 392 kbaud system + +#### 5.8.4.3.2 Power spectral density for 584 kbaud systems + +The upper bound of the average power spectral density of the signal transmitted by the HDSL transmitter shall be as shown in Figure 24. + +- $-39$ dBm/Hz from 0 Hz to 292 kHz; +- $-80$ dB/decade fall from $-39$ dBm/Hz at 292 kHz to $-119$ dBm/Hz at 2.92 MHz; +- $-119$ dBm/Hz above 2.92 MHz. + +![Figure 24/G.991.1: Upper bound of the average power spectral density of a 584 kbaud system. The graph plots dBm/Hz on the y-axis (from -120 to -20) against frequency in Hz on a logarithmic x-axis (from 1e3 to 1e7). The spectral density is constant at -39 dBm/Hz from 1e3 Hz to 2.92e5 Hz, then falls at -80 dB/decade to -119 dBm/Hz at 2.92e6 Hz, and remains constant at -119 dBm/Hz above 2.92e6 Hz. A label 'Floor at -119 dBm/Hz' is present.](37e4831a48bd47b99dcf6837787652ae_img.jpg) + +Figure 24/G.991.1: Upper bound of the average power spectral density of a 584 kbaud system. The graph plots dBm/Hz on the y-axis (from -120 to -20) against frequency in Hz on a logarithmic x-axis (from 1e3 to 1e7). The spectral density is constant at -39 dBm/Hz from 1e3 Hz to 2.92e5 Hz, then falls at -80 dB/decade to -119 dBm/Hz at 2.92e6 Hz, and remains constant at -119 dBm/Hz above 2.92e6 Hz. A label 'Floor at -119 dBm/Hz' is present. + +**Figure 24/G.991.1 – Upper bound of the average power spectral density of a 584 kbaud system** + +### 5.8.4.3.3 Power spectral density for 1160 kbaud systems + +The upper bound of the average power spectral density of the signal transmitted by the HDSL transmitter shall be as shown in Figure 25. + +- -41.5 dBm/Hz from 0 Hz to 485 kHz; +- -80 dB/decade fall from -41.5 dBm/Hz at 485 kHz to -121.5 dBm/Hz at 4.85 MHz; +- -121.5 dBm/Hz above 4.85 MHz. + +![Figure 25/G.991.1: Upper bound of the average power spectral density of a 1160 kbaud system. The graph plots dBm/Hz on the y-axis (from -120 to -20) against frequency in Hz on a logarithmic x-axis (from 1e3 to 1e7). The spectral density is constant at -41.5 dBm/Hz from 1e3 Hz to 4.85e5 Hz, then falls at -80 dB/decade to -121.5 dBm/Hz at 4.85e6 Hz, and remains constant at -121.5 dBm/Hz above 4.85e6 Hz. A label 'Floor at -121.5 dBm/Hz' is present.](624646367ef6cd220973a363f00310a0_img.jpg) + +Figure 25/G.991.1: Upper bound of the average power spectral density of a 1160 kbaud system. The graph plots dBm/Hz on the y-axis (from -120 to -20) against frequency in Hz on a logarithmic x-axis (from 1e3 to 1e7). The spectral density is constant at -41.5 dBm/Hz from 1e3 Hz to 4.85e5 Hz, then falls at -80 dB/decade to -121.5 dBm/Hz at 4.85e6 Hz, and remains constant at -121.5 dBm/Hz above 4.85e6 Hz. A label 'Floor at -121.5 dBm/Hz' is present. + +**Figure 25/G.991.1 – Upper bound of the average power spectral density of a 1160 kbaud system** + +#### 5.8.4.4 Total power + +The average power of a signal – excluding remote power feeding – consisting of a framed sequence of symbols with a frame word and equiprobable symbols in all other positions should be between 13.0 dBm and 14.0 dBm over the frequency band from 0 Hz to 784 kHz for 392 kbaud systems, from 0 Hz to 1168 kHz for 584 kbaud systems and from 0 Hz to 2320 kHz for 1160 kbaud systems. + +#### 5.8.5 Unbalance about earth + +##### 5.8.5.1 Longitudinal conversion loss + +The longitudinal conversion loss is given by: + +$$LCL = 20 \log (e_l/e_m) \text{ [dB]}$$ + +where $e_l$ is the applied longitudinal voltage referenced to the building ground and $e_m$ is the resultant metallic voltage appearing across a 135 ohms termination. + +The longitudinal conversion loss of the system shall meet the requirement of: + +- 50 dB between 5 kHz and 196 kHz for a 392 kbaud system as shown in Figure 26; +- 50 dB between 5 kHz and 292 kHz for a 584 kbaud system as shown in Figure 27; and +- 50 dB between 5 kHz and 485 kHz for a 1160 kbaud system as shown in Figure 28. + +This requirement ensures that the overall LCL is not significantly worse than that of the DLLs alone. + +![Figure 26/G.991.1 – Minimum longitudinal conversion loss for a 392 kbaud system. The graph shows LCL in dB on the y-axis (36 to 52) versus frequency in Hz on a logarithmic x-axis (5 e2 to 1 e7). The curve rises from 36 dB at 5 e2 Hz to 50 dB at 5 e3 Hz, stays at 50 dB until 1.96 e5 Hz, and then falls back to 36 dB at 1 e6 Hz. Slopes of -20 dB/dec are indicated on the rising and falling sections.](eb8a1209049ea1ff9a753c5b25db2e16_img.jpg) + +The figure is a line graph showing the minimum longitudinal conversion loss (LCL) in dB for a 392 kbaud system. The y-axis represents LCL in dB, ranging from 36 to 52 in increments of 2. The x-axis represents frequency in Hz on a logarithmic scale, with major markers at 5 e2, 1 e3, 5 e3, 1 e4, 1 e5, 1.96 e5, 5 e5, 1 e6, and 1 e7. The graph shows a piecewise linear curve: it starts at 36 dB at 5 e2 Hz, rises with a slope of +20 dB/dec to 50 dB at 5 e3 Hz, remains constant at 50 dB until 1.96 e5 Hz, and then falls with a slope of -20 dB/dec to 36 dB at 1 e6 Hz. The labels '-20 dB/dec' are placed on both the rising and falling slopes. A small code 'T1529070-98' is visible in the bottom right corner of the graph area. + +Figure 26/G.991.1 – Minimum longitudinal conversion loss for a 392 kbaud system. The graph shows LCL in dB on the y-axis (36 to 52) versus frequency in Hz on a logarithmic x-axis (5 e2 to 1 e7). The curve rises from 36 dB at 5 e2 Hz to 50 dB at 5 e3 Hz, stays at 50 dB until 1.96 e5 Hz, and then falls back to 36 dB at 1 e6 Hz. Slopes of -20 dB/dec are indicated on the rising and falling sections. + +Figure 26/G.991.1 – Minimum longitudinal conversion loss for a 392 kbaud system + +![Figure 27/G.991.1: Minimum longitudinal conversion loss for a 584 kbaud system. The graph plots dB (36 to 52) against frequency in Hz (logarithmic scale from 5 e2 to 1 e7). The curve rises from 36 dB at 1 e3 Hz to 50 dB at 5 e3 Hz, stays flat until 2.92 e5 Hz, and then falls at -20 dB/dec to 36 dB at 1 e6 Hz.](a4cb63f5debf833e6069e99143a2b624_img.jpg) + +This graph shows the minimum longitudinal conversion loss for a 584 kbaud system. The y-axis represents the loss in dB, ranging from 36 to 52 in increments of 2. The x-axis represents frequency in Hz on a logarithmic scale, with major markers at 5 e2, 1 e3, 5 e3, 1 e4, 1 e5, 2.92 e5, 5 e5, 1 e6, and 1 e7. The curve starts at 36 dB at 1 e3 Hz, rises linearly to 50 dB at 5 e3 Hz, remains constant at 50 dB until 2.92 e5 Hz, and then falls linearly at a rate of -20 dB/dec, reaching 36 dB at 1 e6 Hz. + +Figure 27/G.991.1: Minimum longitudinal conversion loss for a 584 kbaud system. The graph plots dB (36 to 52) against frequency in Hz (logarithmic scale from 5 e2 to 1 e7). The curve rises from 36 dB at 1 e3 Hz to 50 dB at 5 e3 Hz, stays flat until 2.92 e5 Hz, and then falls at -20 dB/dec to 36 dB at 1 e6 Hz. + +**Figure 27/G.991.1 – Minimum longitudinal conversion loss for a 584 kbaud system** + +![Figure 28/G.991.1: Minimum longitudinal conversion loss for a 1160 kbaud system. The graph plots dB (36 to 52) against frequency in Hz (logarithmic scale from 5 e2 to 1 e7). The curve rises from 36 dB at 1 e3 Hz to 50 dB at 5 e3 Hz, stays flat until 4.85 e5 Hz, and then falls at -20 dB/dec to 36 dB at 1 e6 Hz.](eed0af615cb10bce0f91a54071df95ce_img.jpg) + +This graph shows the minimum longitudinal conversion loss for a 1160 kbaud system. The y-axis represents the loss in dB, ranging from 36 to 52 in increments of 2. The x-axis represents frequency in Hz on a logarithmic scale, with major markers at 5 e2, 1 e3, 5 e3, 1 e4, 1 e5, 4.85 e5, 1 e6, and 1 e7. The curve starts at 36 dB at 1 e3 Hz, rises linearly to 50 dB at 5 e3 Hz, remains constant at 50 dB until 4.85 e5 Hz, and then falls linearly at a rate of -20 dB/dec, reaching 36 dB at 1 e6 Hz. + +Figure 28/G.991.1: Minimum longitudinal conversion loss for a 1160 kbaud system. The graph plots dB (36 to 52) against frequency in Hz (logarithmic scale from 5 e2 to 1 e7). The curve rises from 36 dB at 1 e3 Hz to 50 dB at 5 e3 Hz, stays flat until 4.85 e5 Hz, and then falls at -20 dB/dec to 36 dB at 1 e6 Hz. + +**Figure 28/G.991.1 – Minimum longitudinal conversion loss for a 1160 kbaud system** + +Figure 29 defines a measurement method for longitudinal conversion loss. For direct use of this configuration, measurement should be performed with the IUT powered up but inactive (no transmitted signal; driving 0 V). + +![Figure 29/G.991.1 – Measurement method for longitudinal conversion loss. The diagram shows an IUT (Intended Use Terminal) connected to a measuring set (well balanced) via a transformer. The measuring set is connected to a longitudinal signal generator via a series of resistors (R1, R2) and capacitors. The signal generator is connected to a DC voltage source (V_DC) via a series of capacitors. The IUT is connected to ground. The measuring set is labeled 'e_m'. The signal generator is labeled 'e_l'. The resistors R1 and R2 are labeled 'a)'. The transformer is labeled 'b)'. The DC voltage source is labeled 'c)'. The diagram is labeled 'T1529100-98'.](32d36dfe7dc75b7c63f8edf0f28e4009_img.jpg) + +Figure 29/G.991.1 – Measurement method for longitudinal conversion loss. The diagram shows an IUT (Intended Use Terminal) connected to a measuring set (well balanced) via a transformer. The measuring set is connected to a longitudinal signal generator via a series of resistors (R1, R2) and capacitors. The signal generator is connected to a DC voltage source (V\_DC) via a series of capacitors. The IUT is connected to ground. The measuring set is labeled 'e\_m'. The signal generator is labeled 'e\_l'. The resistors R1 and R2 are labeled 'a)'. The transformer is labeled 'b)'. The DC voltage source is labeled 'c)'. The diagram is labeled 'T1529100-98'. + +- a) These resistors have to be matched: $R1 = R2 = 135/2$ ohms and $R1/R2 = 1 \pm 0.1\%$ +- b) For LTU test only if remote power feeding is supplied +- c) For NTU test only if remote power feeding is required + +NOTE – During regenerator test (where required) each wire on the side which is not under test has to be connected to ground by a terminating impedance having the value of $135/2$ ohms in series with a capacitance of $0.33 \mu\text{F}$ . + +**Figure 29/G.991.1 – Measurement method for longitudinal conversion loss** + +### 5.8.5.2 Longitudinal output voltage + +The longitudinal component of the output signal shall have an r.m.s. voltage, in any 4 kHz equivalent bandwidth averaged in any second period, $< -50 \text{ dBV}$ over the frequency range 100 Hz to 400 kHz. Compliance with this limitation is required with a longitudinal termination having an impedance of 100 ohms in series with $0.15 \mu\text{F}$ nominal. Note that the EMC requirements of 9.4 must also be met. + +Figure 30 defines a measurement method for longitudinal output voltage. For direct use of this test configuration, the IUT should be able to generate a signal in the absence of a signal from the far end. The ground reference for these measurements shall be the building ground. + +![Figure 30/G.991.1 – Measurement method for longitudinal output voltage. The diagram shows an IUT (Intended Use Terminal) connected to a spectrum analyser via a series of resistors (R1, R2) and capacitors. The spectrum analyser is connected to a 100 ohms resistor and a 150 nF capacitor in series. The IUT is connected to ground. The resistors R1 and R2 are labeled 'a)'. The transformer is labeled 'b)'. The DC voltage source is labeled 'c)'. The diagram is labeled 'T1529110-98'.](ee0bf6a260cff72af8f0df0639b6a7c5_img.jpg) + +Figure 30/G.991.1 – Measurement method for longitudinal output voltage. The diagram shows an IUT (Intended Use Terminal) connected to a spectrum analyser via a series of resistors (R1, R2) and capacitors. The spectrum analyser is connected to a 100 ohms resistor and a 150 nF capacitor in series. The IUT is connected to ground. The resistors R1 and R2 are labeled 'a)'. The transformer is labeled 'b)'. The DC voltage source is labeled 'c)'. The diagram is labeled 'T1529110-98'. + +- a) These resistors have to be matched: $R1 = R2 = 135/2$ ohms and $R1/R2 = 1 \pm 0.1\%$ +- b) For LTU test only if remote power feeding is supplied +- c) For NTU test only if remote power feeding is required + +NOTE – During regenerator test (where required) each wire on the side which is not under test has to be connected to ground by a terminating impedance having the value of $135/2$ ohms in series with a capacitance of $0.33 \mu\text{F}$ . + +**Figure 30/G.991.1 – Measurement method for longitudinal output voltage** + +## 5.9 Performance of individual HDSL transceivers + +### 5.9.1 Performance requirements + +Performance limits for the overall system are defined for the specific applications of which examples are given in Appendix I. The performance of the individual HDSL transceivers must be such that these overall performance limits are met. As the binary signal of the individual transceivers is not available at an external interface for testing, it is not considered feasible to test the performance of the individual HDSL transceivers. For the purpose of conformance, each HDSL system is required to have an individual performance such that the overall application performance for the appropriate application is met. + +### 5.9.2 DLL physical models (test loops) + +Some representative models of DLLs (test loops) for evaluating the performance of transceivers for transmission systems are defined in Figure 32. + +### 5.9.3 Jitter and wander + +#### 5.9.3.1 General + +The jitter and performance limits specified for appropriate applications (see Appendix I) shall be supported by the jitter limits of the individual HDSL transmission systems. However, due to the bidirectional transmission on the two-wire line and due to severe intersymbol interference no well defined signal transitions are available on the two-wire signal. It will therefore be necessary to provide clock interfaces to enable the following requirements to be tested. The jitter limits given below must be satisfied regardless of the length of the local line and the inclusion of regenerators, provided that they are covered by the transmission media characteristics of 6.3. The limits must be met regardless of the transmitted signal. In this subclause, jitter is specified in terms of Unit Intervals (UI) of the nominal line baud rate which is 392 kbaud (2.55 $\mu$ s) for the three-pair system and 584 kbaud (1.71 $\mu$ s) for the two-pair system and 1160 kbaud (0.862 $\mu$ s) for the one-pair system. + +#### 5.9.3.2 Input jitter tolerance at the HDSL transceiver at the NTU + +The NTU shall meet the performance objectives specified for appropriate applications (see Appendix I) with wander/jitter sinusoidal characteristics as indicated in Figure 31, and with values as defined in Table 17 below for single jitter frequencies in the range of 0.1 Hz to 100 kHz superimposed on the test clock source, and with the received signal baud rate in the range of $\pm 32$ ppm. + +**Table 17/G.991.1 – Values for wander/jitter characteristics** + +| A1 | A2 | f0 | f1 | f2 | f3 | +|-----------------------|------------------------|--------|--------|------|---------| +| 0.15 UI pp | 0.015 UI pp | 0.1 Hz | 0.5 Hz | 5 Hz | 100 kHz | + +![Figure 31/G.991.1 – Range of permissible sinusoidal input jitter. The graph shows Jitter (UI_pp) on the y-axis and Jitter frequency (Log scale) on the x-axis. The y-axis has markers for 0, A2, and A1. The x-axis has markers for f0, f1, f2, and f3. The jitter level is constant at A1 from f0 to f1. From f1 to f2, the jitter level decreases linearly on the log scale with a slope of 20 dB/decade. From f2 to f3, the jitter level is constant at A2. The text 'T1529120-98' is in the bottom right corner.](42f531970fcd8c6856112ade03f4f1f5_img.jpg) + +Figure 31/G.991.1 – Range of permissible sinusoidal input jitter. The graph shows Jitter (UI\_pp) on the y-axis and Jitter frequency (Log scale) on the x-axis. The y-axis has markers for 0, A2, and A1. The x-axis has markers for f0, f1, f2, and f3. The jitter level is constant at A1 from f0 to f1. From f1 to f2, the jitter level decreases linearly on the log scale with a slope of 20 dB/decade. From f2 to f3, the jitter level is constant at A2. The text 'T1529120-98' is in the bottom right corner. + +NOTE – Unit Interval (UI) = 2.55 $\mu\text{s}$ for 392 kbaud systems + – Unit Interval (UI) = 1.71 $\mu\text{s}$ for 584 kbaud systems + – Unit Interval (UI) = 0.862 $\mu\text{s}$ for 1160 kbaud systems + +**Figure 31/G.991.1 – Range of permissible sinusoidal input jitter** + +### 5.9.3.3 Output jitter limitations at the HDSL transceiver at the NTU + +The jitter on the transmitted 2B1Q signal of the NTU towards the LTU in the absence of input jitter shall be less than A2 when measured with a band pass filter having a 20 dB/decade roll off with cut off frequencies at f2 and f3 . + +The maximum (peak) departure of the phase of the output signal from its average phase measured over $1/f_0$ seconds shall not exceed A1. + +### 5.9.3.4 Input jitter tolerance at the HDSL transceiver at the LTU + +The LTU shall meet the performance objectives specified for appropriate applications (see Appendix I) with wander/jitter of A2 for single jitter frequencies in the range of f0 to f3 superimposed on the test clock source, and with the signal baud rate in the range $\pm 32$ ppm. + +### 5.9.3.5 Output jitter limitation of the HDSL transceiver at the LTU + +The jitter on the transmitted 2B1Q signal of the LTU towards the NTU shall be less than A2 when measured with a band pass filter having a 20 dB/decade roll off with cut off frequencies at f2 and f3. + +## 6 Common circuitry specification + +### 6.1 Delay difference buffer + +In order to compensate for any difference in total transmission time of the HDSL frames on different pairs, due to the pair differences described in 5.2.4.2, as well as to delays due to signal processing in the HDSL transceivers in the LTU, NTU and possible REG, a delay difference buffer shall be implemented in the common circuitry. The function of this delay difference buffer is to align the HDSL frames so that the core frames can be correctly reassembled. This buffer should be capable of absorbing a maximum delay difference of 60 $\mu\text{s}$ . + +## 6.2 The pair identification mechanism + +The pair identification procedure provides for the correct information of the NTU on the pair numbers selected by the LTU in a two- or three-pair system. It is based on the use of the Z-bits and is therefore only available for 2048 kbit/s applications. The following is a definition of a pair identification mechanism that has to be completed for each installed pair separately, and agrees with the local procedures for activation. The pair identification procedure is operated only between the LTU and the NTU, the optional REG transfers the related information transparently. + +### 6.2.1 Pair identification initial values + +At the beginning of the start-up procedure, each HDSL transceiver in the LTU is assigned with a pair identification number, which may be 1, 2 or 3 for three-pair systems, or 1 or 2 for two-pair systems. The HDSL transceivers in the NTU are not assigned, but defined by the received Z-bits according to Tables 18 and 19. When an HDSL transceiver at the LTU reaches the Active-Tx/Rx State in the activation procedure, as described in 5.6.5 the common circuitry sets the indicator bits $Z_{m1}$ , $Z_{m2}$ and $Z_{m3}$ for three-pair systems or $Z_{m1}$ and $Z_{m2}$ for two-pair systems according to Tables 18 and 19, using the pair identification number it was assigned. + +**Table 18/G.991.1 – Pair identification bit assignment for the three-pair system** + +| Pair Number [m] | $Z_{m1}$ | $Z_{m2}$ | $Z_{m3}$ | +|-----------------|--------------|--------------|--------------| +| 1 | $Z_{11} = 1$ | $Z_{12} = 0$ | $Z_{13} = 0$ | +| 2 | $Z_{21} = 0$ | $Z_{22} = 1$ | $Z_{23} = 0$ | +| 3 | $Z_{31} = 0$ | $Z_{32} = 0$ | $Z_{33} = 1$ | + +**Table 19/G.991.1 – Pair identification bit assignment for the two-pair system** + +| Pair Number [m] | $Z_{m1}$ | $Z_{m2}$ | +|-----------------|--------------|--------------| +| 1 | $Z_{11} = 1$ | $Z_{12} = 0$ | +| 2 | $Z_{21} = 0$ | $Z_{22} = 1$ | + +### 6.2.2 Pair identification at the NTU + +Prior to the completion of the evaluation process of the individual pair, the transmitted Z-bits are set to ONE. When the HDSL transceiver at the NTU enters the Active-Tx/Rx State the common circuitry starts to look at the Z-bits. If it detects a valid pattern according to Tables 18 or 19 respectively in six consecutive HDSL frames and the same pattern has not been detected on another pair before, then the evaluation process is completed successfully for this pair and the outgoing pair identification Z-bits are set to equal the recognized Z-bits for the whole actual activation period. When the common circuitry detects a complete valid matrix according to Tables 18 or 19 it can achieve the correct data assignment and becomes transparent for the core frame data. + +### 6.2.3 Pair identification at the LTU + +After starting the transmission of the Z-bits the common circuitry starts to look at the received Z-bits. Initially, it should detect that all the pair identification Z-bits are ONE. When the HDSL transceiver at the NTU reflects the received Z-bits the common circuitry at the LTU will detect the pair identification number. When it finds its own valid pattern in six consecutive HDSL frames, the NTU has acknowledged the pair identification for this individual pair. If the Z-bits for all installed pairs are acknowledged the common circuitry becomes transparent for the core frame data. + +The identification procedure introduces a delay of at least 12 frames (72 ms) between transition to the Active-Tx/Rx State and transparent data transfer, because valid patterns are required for six consecutive frames at each side. + +### **6.3 Laboratory performance measurements** + +#### **6.3.1 General** + +The performance requirements have been specified so that the HDSL transceivers are tolerant to NEXT, impulsive noise and shaped noise, and not optimized for only one operating condition. + +The laboratory performance measurement of a particular HDSL transmission system requires the following preparations: + +- definition of a number of DLL models to represent physical and electrical characteristics encountered in local line distribution networks; +- simulation of the electrical environment caused by impulse noise and finite crosstalk coupling loss to other pairs in the same cable; +- specification of laboratory performance tests to verify that the performance limits necessary for different applications will be met. + +Some representative models of DLLs (test loops) for evaluating the performance of transceivers for transmission systems are defined in Figure 32, the basic test cable characteristics are given in Appendix II. + +![Figure 32/G.991.1 – DLL physical models for laboratory testing. The diagram shows eight different physical models (1-8) for digital loop testing, connecting an NTU Customer to an LTU Exchange. Model 1 is a 0 dB loop. Model 2 is a loop with insertion loss Y and 0.4 mm PE cable. Model 3 consists of four sections with 0.5Y, 0.25Y, 0.25Y, and 0.25Y attenuation and cable diameters of 0.4 mm, 0.6 mm, 0.5 mm, and 0.4 mm PE respectively. Model 4 consists of three sections with 0.25Y, 0.5Y, and 0.25Y attenuation and cable diameters of 0.6 mm, 0.4 mm, and 0.5 mm PE respectively. Model 5 consists of three sections with 100 m, 0.8Y, and 100 m length and cable diameters of 0.4 mm PVC, 0.8 mm PE, and 0.4 mm PVC respectively. Model 6 consists of three sections with 0 m, 0.2Y, and 0.5Y attenuation and cable diameters of 0.4 mm PE, with two 500 m BT (bridged tap) sections of 0.4 mm PE cable. Model 7 consists of four sections with 300 m, 0.2Y, Note 5 (0.6 (0.55)Y), and 50 m length and cable diameters of 0.6 mm PVC, 0.5 mm PE, 0.4 mm PE, and 0.3 mm PVC respectively. Model 8 consists of two sections with 0.45Y attenuation and 0.4 mm PE cable, connected to a Common mode insertion circuit (Note 6) with <3 dB loss at 150 kHz. The diagram is labeled T1529130-98.](0adfaa8c2562a9fe3a8a96165d7d59a3_img.jpg) + +Figure 32/G.991.1 – DLL physical models for laboratory testing. The diagram shows eight different physical models (1-8) for digital loop testing, connecting an NTU Customer to an LTU Exchange. Model 1 is a 0 dB loop. Model 2 is a loop with insertion loss Y and 0.4 mm PE cable. Model 3 consists of four sections with 0.5Y, 0.25Y, 0.25Y, and 0.25Y attenuation and cable diameters of 0.4 mm, 0.6 mm, 0.5 mm, and 0.4 mm PE respectively. Model 4 consists of three sections with 0.25Y, 0.5Y, and 0.25Y attenuation and cable diameters of 0.6 mm, 0.4 mm, and 0.5 mm PE respectively. Model 5 consists of three sections with 100 m, 0.8Y, and 100 m length and cable diameters of 0.4 mm PVC, 0.8 mm PE, and 0.4 mm PVC respectively. Model 6 consists of three sections with 0 m, 0.2Y, and 0.5Y attenuation and cable diameters of 0.4 mm PE, with two 500 m BT (bridged tap) sections of 0.4 mm PE cable. Model 7 consists of four sections with 300 m, 0.2Y, Note 5 (0.6 (0.55)Y), and 50 m length and cable diameters of 0.6 mm PVC, 0.5 mm PE, 0.4 mm PE, and 0.3 mm PVC respectively. Model 8 consists of two sections with 0.45Y attenuation and 0.4 mm PE cable, connected to a Common mode insertion circuit (Note 6) with <3 dB loss at 150 kHz. The diagram is labeled T1529130-98. + +NOTE 1 – The value for Y (insertion loss in dB at 150 kHz) is to be found in Table 20. + +NOTE 2 – Due to mismatches and bridged taps (BTs) the total DLL attenuation differs from the sum of the attenuation of the parts. Appendix II provides theoretical values for the transmission parameters of the above loops. + +NOTE 3 – Attenuation of separate sections is measured with a 135 ohms termination. + +NOTE 4 – These test loops and artificial cable parameters include worst case examples as well as those more typical of a local network. They are chosen to provide the wide range of different echoes and distortions which may occur in European networks. + +NOTE 5 – The value in brackets is valid for one-pair systems only. The reduction is necessary to compensate the higher attenuation of the fixed sections. + +NOTE 6 – See Figure 33. + +**Figure 32/G.991.1 – DLL physical models for laboratory testing** + +### 6.3.2 Test configuration + +It is assumed that the various applications shall operate over a number of pairs each connected to an individual 784 kbit/s, 1168 kbit/s or 2320 kbit/s 2B1Q duplex HDSL transmission system. For various applications and bit rates different numbers of pairs may be required. Performance requirements should relate to the integrity of the data at the application interface when individual transmission systems are subjected to synthesized impairments. In this way access is not required to + +the raw data transported by the individual transceivers. Data errors can therefore be measured at the application interface, avoiding the need for test access to the individual data channels. + +A representative test arrangement is shown in Figure 34. + +The Bit Error Ratio Test Set (BERTS) applies a $2^{15}-1$ Pseudo-Random Bit Sequence (PRBS) test signal to the transmitter in the direction under test at the bit rate required by the application interface. Impairments (when required by the test) are injected at the input of the appropriate HDSL transceivers at the receiver end of the path, and the reconstructed data is then returned to the BERTS. The transmitter in the opposing direction shall be fed with a similar PRBS signal, although the reconstructed signal in this path need not be monitored. + +The test performance of the HDSL transceiver shall be such that the bit error ratio (BER) on the disturbed system is less than ( $10^{-7}$ divided by the number of pairs) while transmitting a pseudo-random bit sequence. The BER should be measured after at least $10^9$ bits have been transmitted. + +The tests are carried out with zero margin, i.e. with no additional attenuation added to the test pairs. It is expected that network operators will calculate their own margins for planning purposes based on a knowledge of the relationship between this standard test set and their network characteristics. + +It is considered sufficient to use a representative combination of test pairs for performance testing. The test pairs should be adjusted to achieve the required sinewave insertion loss of the individual sections when measured at 150 kHz. (It is not considered reliable to measure the overall sinewave attenuation, as impedance discontinuities can result in non-linear effects in the frequency response of some pairs.) + +Two distinct classes of added disturbance are injected: Shaped test noise (specified in 6.3.3) and Impulses (defined in 6.3.4). A further test (specified in 6.3.5) tests the common mode rejection capability of the system under test, and a test for determining the susceptibility to micro-interruptions is given in 6.3.6. + +Test sequences are shown in Table 20. + +**Table 20/G.991.1 – Test sequence for performance testing** + +| N | Test path | Direction | Comments | +|---|----------------|-----------|----------------------------------------------------------------------------------------------------------------------------------| +| 1 | #1
(Note 1) | Forward | $Y = 0$ dB; Test noise of 6.3.3 with $N1 = 300 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 30 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 2 | #2 | Forward | $Y = Y1$ (Note 2); Test noise of 6.3.3 with $N1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 3 | #3 | Forward | $Y = Y1$ ; Test noise of 6.3.3 with $N1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 4 | #3 | Reverse | $Y = Y1$ ; Test noise of 6.3.3 with $N1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 5 | #4 | Forward | $Y = Y1$ ; Test noise of 6.3.3 with $N1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 6 | #4 | Reverse | $Y = Y1$ ; Test noise of 6.3.3 with $N1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 7 | #5 | Forward | $Y = Y1$ ; Test noise of 6.3.3 with $N1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | + +**Table 20/G.991.1 – Test sequence for performance testing (concluded)** + +| N | Test path | Direction | Comments | +|----|-----------|---------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------| +| 8 | #6 | Forward | $Y = Y_1$ ; Test noise of 6.3.3 with $N_1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N_2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 9 | #6 | Reverse | $Y = Y_1$ ; Test noise of 6.3.3 with $N_1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N_2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 10 | #7 | Forward | $Y = Y_1$ ; Test noise of 6.3.3 with $N_1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N_2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 11 | #7 | Reverse | $Y = Y_1$ ; Test noise of 6.3.3 with $N_1 = 100 \mu\text{V}/\sqrt{\text{Hz}}$ and $N_2 = 10 \mu\text{V}/\sqrt{\text{Hz}}$ ; | +| 12 | #8 | Forward | $Y = Y_1$ ; Common mode rejection test of 6.3.5 | +| 13 | Note 3 | Forward and reverse | $Y = Y_2$ ; Test noise of 6.3.3 with $N_1 = 300 \mu\text{V}/\sqrt{\text{Hz}}$ and $N_2 = 30 \mu\text{V}/\sqrt{\text{Hz}}$ ; Worst path of tests 1 to 11 | +| 14 | Note 3 | Note 3 | $Y = Y_3$ ; No added impairment; Worst path of tests 1 to 11; $\text{BER} < 10^{-8}$ | +| 15 | #2 | Forward | $Y = Y_1$ ; Impulse test as described in 6.3.4 | +| 16 | As 6.3.6 | Forward | Micro interruption test as described in 6.3.6 | + +NOTE 1 – Test Path = #1 means that the path under test shall be connected with test loop #1 as defined in Figure 32. The path(s) not under test shall be connected with a dummy loop, normally loop #1. + +NOTE 2 – $Y_1 = 22 \text{ dB}$ for the one-pair system, $27 \text{ dB}$ for the two-pair system and $31 \text{ dB}$ for the three-pair system. + +$Y_2 = Y_1 - 10 \text{ dB}$ and $Y_3 = Y_1 + 3 \text{ dB}$ . + +NOTE 3 – The tests are carried out on the worst path in the worst direction from tests 1 to 11, with dummy loop(s) for the remaining path(s). If there are no errors, then loop #2 forward for path A is taken as default. + +NOTE 4 – The tests 1 to 15 shall be carried out on all pairs. In the case of fractionally installed HDSL system, the tests shall be carried out only on the installed pair(s). + +![Circuit diagram of the common mode insertion test circuit. It shows a two-wire transmission line with four identical termination networks at both ends. Each network consists of a 550 ohm resistor in series with a 0.33 µF capacitor to ground. A common mode voltage source V_t is connected between the two wires at the far end. At the near end, a common mode voltage V_0 is measured across the two wires. A ground symbol is shown at the bottom center.](b71ad9fc874230de9ba4480e12a216f7_img.jpg) + +Circuit diagram of the common mode insertion test circuit. It shows a two-wire transmission line with four identical termination networks at both ends. Each network consists of a 550 ohm resistor in series with a 0.33 µF capacitor to ground. A common mode voltage source V\_t is connected between the two wires at the far end. At the near end, a common mode voltage V\_0 is measured across the two wires. A ground symbol is shown at the bottom center. + +NOTE 1 – The minimum return loss of the terminated test insertion circuit shall be better than the minimum return loss of the system. + +NOTE 2 – The minimum longitudinal conversion loss $[20 \log (V_0/V_t)]$ of the test insertion circuit shall be better than $80 \text{ dB}$ at $50 \text{ Hz}$ , decreasing with $20 \text{ dB/decade}$ up to $1 \text{ kHz}$ (above $1 \text{ kHz}$ transversal voltage is negligible compared with the test noise). + +**Figure 33/G.991.1 – Common mode insertion test circuit** + +![Figure 34/G.991.1 – Configuration for performance tests of an access digital section. The diagram shows a 'Transmit pattern' from a '2 Mbit/s Pattern Generator' to an 'NTU/LTU (Note 1)'. The NTU/LTU has three parallel paths: Path A, Path B, and Path C, each with a corresponding channel (HA, HB, HC). These paths lead to another 'NTU/LTU (Note 1) Transceiver under test' which has channels HA', HB', and HC'. A 'Receive pattern' is sent from the transceiver back to a '2 Mbit/s Measurement Equipment (BERTS)'. An arrow labeled 'Direction under test' points from left to right between the two NTU/LTU units.](5cc4a2ef554f31ea0577731931007fff_img.jpg) + +Figure 34/G.991.1 – Configuration for performance tests of an access digital section. The diagram shows a 'Transmit pattern' from a '2 Mbit/s Pattern Generator' to an 'NTU/LTU (Note 1)'. The NTU/LTU has three parallel paths: Path A, Path B, and Path C, each with a corresponding channel (HA, HB, HC). These paths lead to another 'NTU/LTU (Note 1) Transceiver under test' which has channels HA', HB', and HC'. A 'Receive pattern' is sent from the transceiver back to a '2 Mbit/s Measurement Equipment (BERTS)'. An arrow labeled 'Direction under test' points from left to right between the two NTU/LTU units. + +a) Test configuration + +![Diagram showing details of the test configuration. On the left, a dashed box labeled 'Path under test' contains 'Test loop #N', a 'High impedance insertion circuit' (represented by a circle with a cross), an 'Impulse generator', and a 'Test noise generator' connected to a 'dB' meter. On the right, another dashed box labeled 'Path(s) not under test' contains 'Test loop #1'.](2b60ebe01f77d22e53da1fbe73083b01_img.jpg) + +Diagram showing details of the test configuration. On the left, a dashed box labeled 'Path under test' contains 'Test loop #N', a 'High impedance insertion circuit' (represented by a circle with a cross), an 'Impulse generator', and a 'Test noise generator' connected to a 'dB' meter. On the right, another dashed box labeled 'Path(s) not under test' contains 'Test loop #1'. + +b) Details of paths A, B and C + +![Diagram illustrating test permutations for paths A, B, and C. It shows four scenarios: 1. 'LTU test, Forward loop': NTU to LTU with impairments 'I' and a value of '6'. 2. 'LTU test, Reverse loop': NTU to LTU with impairments 'I' and a value of '6 R'. 3. 'NTU test, Forward loop': NTU to LTU with impairments 'I' and a value of '6'. 4. 'NTU test, Reverse loop': NTU to LTU with impairments 'I' and a value of '6 R'. Each scenario includes a 'BER' (Bit Error Rate) measurement point. The text 'T1529150-98' is visible in the bottom right.](1c79f31a718d63814feb28ab46f64f19_img.jpg) + +Diagram illustrating test permutations for paths A, B, and C. It shows four scenarios: 1. 'LTU test, Forward loop': NTU to LTU with impairments 'I' and a value of '6'. 2. 'LTU test, Reverse loop': NTU to LTU with impairments 'I' and a value of '6 R'. 3. 'NTU test, Forward loop': NTU to LTU with impairments 'I' and a value of '6'. 4. 'NTU test, Reverse loop': NTU to LTU with impairments 'I' and a value of '6 R'. Each scenario includes a 'BER' (Bit Error Rate) measurement point. The text 'T1529150-98' is visible in the bottom right. + +c) Example illustrating test permutations + +NOTE 1 – Some tests are carried out in both the forward and reverse direction. + +NOTE 2 – Paths B and C are not used for all HDSL systems or applications. + +**Figure 34/G.991.1 – Configuration for performance tests of an access digital section** + +### 6.3.3 Test procedure with shaped noise + +#### 6.3.3.1 General + +The noise in the local network lines can be represented by an artificial noise source as described below. This artificial noise offers a worst case test condition for intersystem and intrasystem crosstalk for all presently known disturbers. + +The characteristics of the noise are as follows: + +- a) The PSD of the noise is given by the formula below and shown in Figure 35: + - N1 between 320 Hz and 1 kHz; + - N2 between 10 kHz and 1.5 MHz + - (The signal falls off between 1 kHz and 10 kHz at 20 dB/decade); + - Noise PSD; + - ###V/###Hz. + +![Figure 35/G.991.1 – Test noise characteristics. A graph showing Power Spectral Density (PSD) versus Frequency (kHz). The y-axis is labeled N1 and N2. The x-axis is labeled Frequency (kHz) and has tick marks at 0.32, 1, 10, and 1500 kHz. The graph shows a piecewise linear function: a horizontal line at N1 from 0.32 kHz to 1 kHz, a downward sloping line from N1 at 1 kHz to N2 at 10 kHz, and a horizontal line at N2 from 10 kHz to 1500 kHz.](f5604ff55013f105ac5be69097c5470f_img.jpg) + +T1529160-98 + +Figure 35/G.991.1 – Test noise characteristics. A graph showing Power Spectral Density (PSD) versus Frequency (kHz). The y-axis is labeled N1 and N2. The x-axis is labeled Frequency (kHz) and has tick marks at 0.32, 1, 10, and 1500 kHz. The graph shows a piecewise linear function: a horizontal line at N1 from 0.32 kHz to 1 kHz, a downward sloping line from N1 at 1 kHz to N2 at 10 kHz, and a horizontal line at N2 from 10 kHz to 1500 kHz. + +Figure 35/G.991.1 – Test noise characteristics + +- b) The values N1 and N2 differ for "Standard Noise" and "Increased Noise". + - Standard Noise: N1 = 100 ###V/###Hz +N2 = 10 ###V/###Hz +These levels correspond to a 53 dB NEXT at 150 kHz. + - Increased Noise: N1 = 300 ###V/###Hz +N2 = 30 ###V/###Hz +These levels correspond to a 41 dB NEXT at 150 kHz. +- c) The "Standard Noise" has an r.m.s. voltage of 13 mV in the frequency band up to 1.5 MHz when measured with the injection circuitry described below. + +#### 6.3.3.2 Generation + +The artificial noise shall be constructed using discrete sinewaves with frequencies of $f = n \times 320$ Hz in the range 320 Hz to 1.5 MHz. The level of the individual sinewaves is: $\text{###}(320 \text{ Hz}) \times n$ ( $n = N1$ or $N2$ as appropriate). + +The phase relationships of the different sinewaves is given as the *Shapiro-Rudin Phases* in an article by Stephen Boyd [B4]; *Multitone Signals with Low Crest Factor* in IEEE Transactions on Circuits + +and Systems vol CAS-33 No. 10; October 1986. This will give a signal with a crest factor of about 2.8. + +NOTE – Noise with a crest factor of 2.8 is not necessarily representative of crosstalk found in typical access networks where crosstalk has been measured to have a distribution which is close to Gaussian to a crest factor in excess of 4.5. Low crest factor noise does however provide for rapid and repeatable systems tests. This discrepancy is subject to further study. + +### 6.3.3.3 Injection + +The injection circuit should have a Thevenin output impedance of at least 4 kOhms. The shaped noise voltage density should be measured at the output of the shunt injection circuit of Figure 34, with the test loop replaced by a 67.5 ohms resistor and no terminal equipment connected. + +### 6.3.3.4 Tolerances and calibration + +Note that the accuracy of performance margins will depend on the measurement accuracy, in particular the tolerance of the noise source and the loop simulator. + +#### 6.3.3.4.1 0 dB level calibration + +The noise source may be calibrated so that the averaged summation of the noise power spectral density over the bandwidth of interest (usually the transmit spectrum of the system under test) conforms with the specification above. This averaged noise power shall be accurate to within $\pm 1$ dB of that specified. If the setting of the noise source is changed by this calibration the new value shall be used as the 0 dB level. + +Noise sources from different manufacturers may cause slightly different noise power despite correct calibration and lead to differing measurement results. + +#### 6.3.3.4.2 Test loop tolerances + +The frequency response of the simulated test loops may deviate from the ideal given in Appendix II. This fact may lead to differing measurement results, especially when simulators from different manufacturers are used, and no calibration procedure is known to compensate for this difference. + +## 6.3.4 Test procedure for impulse noise + +### 6.3.4.1 Impulse noise test waveform + +The impulse noise waveform $V(t)$ (hereafter called the "test impulse" and also known as the "Cook pulse") is defined as: + +$$V(t) = +K|t|^{-3/4} \quad (t > 0)$$ + +$$V(t) = 0 \quad (t = 0)$$ + +$$V(t) = -K|t|^{-3/4} \quad (t < 0)$$ + +where $t$ is time given in units of seconds (s) and $K$ is a constant defined numerically in Table 21. + +**Table 21/G.991.1 – Performance requirements for impulse noise test** + +| Peak-to-peak amplitude ( $V_{pp}$ ) of the test impulse when sampled at 2 Msamples/s (Note 1) | K | Bit error ratio upper limit when measured at the application interface (Note 2) | +|-----------------------------------------------------------------------------------------------|------------------------|---------------------------------------------------------------------------------| +| 320 mV (0 dB level) | $1775 \times 10^{-6}$ | $(9/N) \times 10^{-4}$ | +| 160 mV (–6 dB level) | $8875 \times 10^{-7}$ | $(12/N) \times 10^{-5}$ | +| 80 mV (–12 dB level) | $44375 \times 10^{-7}$ | $(14/N) \times 10^{-6}$ | + +NOTE 1 – The peak-to-peak amplitude will vary with sampling rate and may be easily calculated from the following expression for sampling rates other than 2 Msamples/s. If the sampling rate is $1/T$ samples/s then $V_{pp} = 2K|T/2|^{-3/4}$ . + +NOTE 2 – $N = 1$ for a 2320 kbit/s one-pair system, $N = 2$ for a 1168 kbit/s two-pair system and $N = 3$ for a 784 kbit/s three-pair system. + +A sampled version of the test impulse should be used with samples at $t = (2n - 1)T/2$ . The sampling rate ( $1/T$ ) should be at least twice the baud rate of the system under test. A minimum number of 8 ksamples (i.e. $\pm 4$ ksamples) is required with an amplitude accuracy of at least 12 bits. It is important to note that there is no sample at $t = 0$ . A window on the sampled test impulse is shown in Figure 36. + +![Figure 36/G.991.1 – Time domain representation of the test impulse sampled at 2 Msamples/s with 12 bit accuracy. The graph shows Relative amplitude on the y-axis (from -1.0 to 1.0) versus time in microseconds on the x-axis (from -10 to 10). The impulse is a sharp vertical line at t=0, reaching a peak of 1.0 and a trough of -1.0. The signal then decays rapidly, showing a series of steps, and stabilizes near zero amplitude for t > 5 microseconds. The label T1529170-98 is visible in the bottom right corner of the plot area.](eec47775133f5c3b02d42ab8f85599ce_img.jpg) + +Figure 36/G.991.1 – Time domain representation of the test impulse sampled at 2 Msamples/s with 12 bit accuracy. The graph shows Relative amplitude on the y-axis (from -1.0 to 1.0) versus time in microseconds on the x-axis (from -10 to 10). The impulse is a sharp vertical line at t=0, reaching a peak of 1.0 and a trough of -1.0. The signal then decays rapidly, showing a series of steps, and stabilizes near zero amplitude for t > 5 microseconds. The label T1529170-98 is visible in the bottom right corner of the plot area. + +**Figure 36/G.991.1 – Time domain representation of the test impulse sampled at 2 Msamples/s with 12 bit accuracy** + +### 6.3.4.2 Impulse noise test measurement + +The test impulse shall be applied to the system under test at a rate of 10 Hz. The test period shall be at least 10 s (i.e. >100 impulses should be applied). + +The test configuration shall be as described in 6.3.2, with the bit error ratio test set (BERTS) configured to display bit error ratio. + +The test impulse waveform shall be transformer coupled to the line via a well balanced shunt injection circuit. The injection circuit should have 4 kohms Thevenin impedance to present minimal loading to the transmission line. + +### 6.3.4.3 Impulse noise test performance requirements + +The maximum bit error ratio for the three levels of impulse noise is given in Table 21. The peak-to-peak amplitude of the test impulse noise is given in mV (and in dB relative to a reference level of 320 mV) measured at the output of the shunt injection circuit, loaded with a 67.5 ohms resistor. + +The minimum value of Y (attenuation of the test pair in dB at 150 kHz) to be used for the impulse noise measurement for various applications is $Y_1 = 22$ dB for the one-pair system, $Y_1 = 27$ dB for the two-pair system and $Y_1 = 31$ dB for the three-pair system. + +### 6.3.5 Common mode rejection test + +This procedure is intended to test the common mode rejection capability of an implementation. Test Loop 8 shall be used with a common mode triangle signal of 50 Hz with a voltage of 15 V r.m.s. for the first harmonic (25.5 Vp). The 21st harmonic (1050 Hz) shall be 53 to 56 dB below the level of the first harmonic. The measured BER shall be less than $(1/N) \times 10^{-7}$ , where N is the number of pairs used. + +The circuit for common mode insertion is shown in Figure 33. + +### 6.3.6 Micro interruption test + +The configuration for micro interruption susceptibility test is shown in Figure 37. + +In this arrangement a periodic trigger signal S stimulates a micro-relay device inducing periodic micro-interruptions on one of the pairs forming the transmission link. Using the test arrangement as described in Figure 32, each HDSL transceiver shall not be reset by a micro interruption of at least $t = 10$ ms when stimulated with a signal of period $T = 5$ s. + +![Figure 37/G.991.1 – Micro interruption test circuit diagram. The diagram shows an NTU (Network Termination Unit) connected to an LTU (Line Termination Unit) via four parallel lines. One of these lines is connected to a micro-relay device. The micro-relay is controlled by an impulse generator, which produces a periodic square wave with pulse width 't' and period 'T'. A detailed view of the micro-relay circuit shows a resistor R = 810 ohms and a capacitor C > 330 nF connected in parallel with the relay coil. The text 'T1529180-98' is visible in the bottom right corner of the diagram area.](1cc00f6edddba3538fdf6991174e5650_img.jpg) + +Figure 37/G.991.1 – Micro interruption test circuit diagram. The diagram shows an NTU (Network Termination Unit) connected to an LTU (Line Termination Unit) via four parallel lines. One of these lines is connected to a micro-relay device. The micro-relay is controlled by an impulse generator, which produces a periodic square wave with pulse width 't' and period 'T'. A detailed view of the micro-relay circuit shows a resistor R = 810 ohms and a capacitor C > 330 nF connected in parallel with the relay coil. The text 'T1529180-98' is visible in the bottom right corner of the diagram area. + +NOTE – The test shall be carried out for each transceiver pair constituting the transmission link. + +**Figure 37/G.991.1 – Micro interruption test circuit** + +## 7 Power feeding + +### 7.1 General + +This clause deals with remote power feeding of regenerator or NTU and wetting current requirements. + +Remote power feeding of the NTU is only required in some applications. Remote power feeding of optional regenerators is a requirement. However a detailed specification of a regenerator is outside the scope of this Recommendation. + +The case where regenerator and NTU are both remotely powered is excluded since it is considered not feasible within the limited power budget available. + +Due to the: + +- different national safety requirements; +- different DLL planning rules; +- the optional use of regenerators; and +- the application dependant requirement to power the NTU, + +no detailed power feeding requirement is provided. Instead general guidelines are provided for the situations where remote powering is required. + +### 7.2 Wetting current + +Wetting current may be used to prevent corrosion of contacts. In the case of remote power feeding the feeding current is enough to fulfil the wetting current requirements. + +Figure 38 gives the basic concept for the provision of wetting current. + +![Figure 38/G.991.1 – Basic method for provision of wetting current. The diagram shows a circuit with two vertical dashed lines representing the NTU (Network Termination Unit) and LTU (Line Termination Unit) interfaces. To the left of the first dashed line is a black rectangular block representing the NTU. To the right of the second dashed line is a black rectangular block representing the LTU. Between the two dashed lines, there is a circuit path with a capacitor and a resistor in series. A box labeled 'Wetting current source' is connected to this path. The text 'T1529190-98' is visible in the bottom right corner of the diagram area.](bbd36eba6bb7c4ba87608874c8c714ff_img.jpg) + +Figure 38/G.991.1 – Basic method for provision of wetting current. The diagram shows a circuit with two vertical dashed lines representing the NTU (Network Termination Unit) and LTU (Line Termination Unit) interfaces. To the left of the first dashed line is a black rectangular block representing the NTU. To the right of the second dashed line is a black rectangular block representing the LTU. Between the two dashed lines, there is a circuit path with a capacitor and a resistor in series. A box labeled 'Wetting current source' is connected to this path. The text 'T1529190-98' is visible in the bottom right corner of the diagram area. + +**Figure 38/G.991.1 – Basic method for provision of wetting current** + +The wetting current shall be less than 20 mA. + +### 7.3 Remote power feeding aspects + +Parallel power feeding is recommended as the basic method of power feeding for all HDSL applications and configurations + +The NTU/REG shall be able to deal with polarity reversal. + +Figure 39 shows the basic circuit for parallel power feeding. + +![Figure 39/G.991.1 – Parallel power feeding diagram. It shows a Network Termination Unit (NTU) on the left and a Line Termination Unit (LTU) on the right, connected by two parallel lines. The NTU contains a 'Power sink' block connected to the lines via two capacitors. The LTU contains a 'Power source' block connected to the lines via two capacitors. The diagram is labeled T1529200-98.](401f020d9ab5904f584424eabb596d2c_img.jpg) + +Figure 39/G.991.1 – Parallel power feeding diagram. It shows a Network Termination Unit (NTU) on the left and a Line Termination Unit (LTU) on the right, connected by two parallel lines. The NTU contains a 'Power sink' block connected to the lines via two capacitors. The LTU contains a 'Power source' block connected to the lines via two capacitors. The diagram is labeled T1529200-98. + +**Figure 39/G.991.1 – Parallel power feeding** + +### 7.3.1 Remote power feeding aspects at the LTU + +If the LTU provides remote power this power is shared over all the available pairs. This should prevent the majority of the power from being transported over the pair with the lowest resistance. + +### 7.3.2 Remote power feeding aspects at the NTU + +Power will be delivered to the NTU via each HDSL pair. The total power (derived from all available pairs) can be used to operate the NTU. HDSL transceivers which are not active may be placed in a low power consumption mode or switched off. + +### 7.3.3 Remote power feeding aspects at the regenerator + +Remote power feeding of a regenerator shall be done on a per pair basis. + +The regenerator shall, if required, also provide wetting current towards the NTU. The amount of wetting current which can be provided may be dependant on the available power budget. + +Figure 40 shows the basic circuit for remote power feeding of a regenerator and provision of wetting current. + +![Figure 40/G.991.1 – Basic concept to power a regenerator and to provide wetting current diagram. It shows an NTU on the left, a REG (regenerator) in the center, and an LTU on the right. The REG is enclosed in a dashed box and contains a 'Power sink' block. It is connected to the NTU and LTU via two parallel lines. The REG has two capacitors on each side (NTU and LTU) and two resistors in series with the power sink block. The diagram is labeled T1529210-98.](7c57192c514175021e4560a1a46126c1_img.jpg) + +Figure 40/G.991.1 – Basic concept to power a regenerator and to provide wetting current diagram. It shows an NTU on the left, a REG (regenerator) in the center, and an LTU on the right. The REG is enclosed in a dashed box and contains a 'Power sink' block. It is connected to the NTU and LTU via two parallel lines. The REG has two capacitors on each side (NTU and LTU) and two resistors in series with the power sink block. The diagram is labeled T1529210-98. + +**Figure 40/G.991.1 – Basic concept to power a regenerator and to provide wetting current** + +## 8 Environmental requirements + +### 8.1 Climatic conditions + +Climatograms which may be applicable to the operation of HDSL equipment can be found in IEC 60721-3 [5]. The choice of classes is under national responsibility. + +## **8.2 Safety** + +No safety requirements are specified under this Recommendation. + +NOTE – IEC 60950 [6] may be applicable. + +## **8.3 Overvoltage protection** + +No overvoltage protection requirements are specified under this Recommendation. + +NOTE – Dependent on the equipment NTU, LTU or REG, Recommendations K.21 [9], K.20 [8] or K.17 [7] may be applicable. + +## **8.4 Electromagnetic compatibility (EMC)** + +The EMC requirement values are outside the scope of this Recommendation. CISPR 22 [10] and national regulations may be applicable. + +### **ANNEX A** + +#### **Transmission system for 1544 kbit/s two-pair system application** + +For the transport of 1544 kbit/s based applications, a different transmission system is used. A description has been published in ANSI Committee T1 Technical Report No. 28 [B3]. + +Only two-pair systems are proposed in this report. No pair identification mechanism as described in 6.2 for 2048 kbit/s based applications is possible with this transmission systems. + +#### **A.1 Frame structure of the two-pair system for 784 kbit/s** + +Figure A.1 illustrates the HDSL frame structure composed of quaternary symbols (quats) and the mapping of the core frame bytes to it. The frame is subdivided into four groups. The first group of the frame starts with the seven symbols long synchronization word followed by one HDSL overhead quat and twelve blocks of HDSL payload, each consisting of 48.5 quats, equivalent to 97 bits, containing the framing bit F and twelve bytes of the application frame. + +![Diagram of HDSL frame structure for a two-pair system. The top part shows a sequence of quaternary symbols (quats) starting with a Sync Word (7q), followed by overhead (1q, 12x48 1/2 = 582q, 5q, 582q, 5q, 582q, 5q, 582q), and ending with stuffing quats (0, 2q) and another Sync Word. The total frame length is 2351 or 2353 quats, with a duration of (6 - 1/392) or (6 + 1/392) ms. Below this, 'Pair 1' is shown with a framing bit 'F' and bytes 1 through 12. 'Pair 2' is shown with a framing bit 'F' and bytes 13 through 24. A detail of a byte shows 8 bits (1b) as 4 quats (1/2q). The total payload for both pairs is 97 bits, 48 1/2 quats, with a duration of 97/784 ms. The diagram is labeled 'T1529220-98'.](7b7596fb5ef925025341a9aacb6f2be7_img.jpg) + +Diagram of HDSL frame structure for a two-pair system. The top part shows a sequence of quaternary symbols (quats) starting with a Sync Word (7q), followed by overhead (1q, 12x48 1/2 = 582q, 5q, 582q, 5q, 582q, 5q, 582q), and ending with stuffing quats (0, 2q) and another Sync Word. The total frame length is 2351 or 2353 quats, with a duration of (6 - 1/392) or (6 + 1/392) ms. Below this, 'Pair 1' is shown with a framing bit 'F' and bytes 1 through 12. 'Pair 2' is shown with a framing bit 'F' and bytes 13 through 24. A detail of a byte shows 8 bits (1b) as 4 quats (1/2q). The total payload for both pairs is 97 bits, 48 1/2 quats, with a duration of 97/784 ms. The diagram is labeled 'T1529220-98'. + +HDSL Payload Block (48 per HDSL Frame) + +| Symbol | Name, Function | +|------------|--------------------------------------------------| +| B01 to B48 | HDSL system payload blocks | +| Byte n | Byte n from application frame (n = 1 ... 24) | +| F | Framing bit of application frame | +| HOH | HDSL overhead (sw, eoc, crc, ...) | +| quat | Quaternary symbol | +| SQ1, SQ2 | Stuff quats | +| Sync word | 7-symbol Barker codes, "double Barker" → 14 bits | + +**Figure A.1/G.991.1 – Frame structure of the two-pair system for 784 kbit/s** + +The three groups following the first group have an equal structure. Each consists of five HDSL overhead quats and twelve HDSL payload blocks as described above. So one frame contains a synchronization word, 16 HDSL overhead quats, 48 F-bits and 576 bytes of the application frame payload. + +At the end of the frame the possibility of two stuffing quats is foreseen. These quats are always used together; this means either none or two stuffing quats are inserted, depending on the relation of the timing. The length of the HDSL frame is either 2353 quats, which equals $6 + \frac{1}{392}$ ms for the nominal HDSL clock frequency, or 2351 quats corresponding to $6 - \frac{1}{392}$ ms and the average will tend to 2352 quats or 6 ms. The receiver is able to evaluate the length of an incoming frame by + +detection of the sync word in the following frame and to adjust the demultiplexing of the data stream. + +**Table A.1/G.991.1 – HDSL frame structure for the two-pair system for 784 kbit/s** + +| Time | Frame Bit # | HOH Bit # | Abbr. name | Full name | Notes | +|------|-------------|-----------|------------|-----------------------------------------------------------|--------------------| +| 0 ms | 1-14 | 1-14 | SW 1-14 | Sync word | Double Barker Code | +| | 15 | 15 | losd | loss of input signal at the far end application interface | | +| | 16 | 16 | febe | far end block error | | +| | 17-1180 | – | B01-B12 | payload block 1-12 | HDSL payload | +| | 1181 | 17 | eoc01 | eoc address | | +| | 1182 | 18 | eoc02 | eoc address | | +| | 1183 | 19 | eoc03 | eoc data/opcode | | +| | 1184 | 20 | eoc04 | eoc odd/even Byte | | +| | 1185 | 21 | crc1 | cyclic redundancy check | CRC-6 | +| | 1186 | 22 | crc2 | cyclic redundancy check | CRC-6 | +| | 1187 | 23 | ps1 | NTU power status bit 1 | NTU → LTU only | +| | 1188 | 24 | ps2 | NTU power status bit 2 | NTU → LTU only | +| | 1189 | 25 | bpv | bipolar violation | | +| | 1190 | 26 | eoc05 | eoc unspecified | | +| | 1191-2354 | – | B13-B24 | payload blocks 13-24 | HDSL payload | +| | 2355 | 27 | eoc06 | eoc message bit 1 | | +| | 2356 | 28 | eoc07 | eoc message bit 2 | | +| | 2357 | 29 | eoc08 | eoc message bit 3 | | +| | 2358 | 30 | eoc09 | eoc message bit 4 | | +| | 2359 | 31 | crc3 | cyclic redundancy check | CRC-6 | +| | 2360 | 32 | crc4 | cyclic redundancy check | CRC-6 | +| | 2361 | 33 | hrp | regenerator present | LTU ← REG → NTU | +| | 2362 | 34 | uib | unspecified indicator bit | | +| | 2363 | 35 | uib | unspecified indicator bit | | +| | 2364 | 36 | uib | unspecified indicator bit | | +| | 2365-3528 | – | B25-B36 | payload blocks 25-36 | HDSL payload | +| | 3529 | 37 | eoc10 | eoc message bit 5 | | +| | 3530 | 38 | eoc11 | eoc message bit 6 | | +| | 3531 | 39 | eoc12 | eoc message bit 7 | | +| | 3532 | 40 | eoc13 | eoc message bit 8 | | +| | 3533 | 41 | crc5 | cyclic redundancy check | CRC-6 | +| | 3534 | 42 | crc6 | cyclic redundancy check | CRC-6 | +| | 3535 | 43 | uib | unspecified indicator bit | | + +**Table A.1/G.991.1 – HDSL frame structure for the two-pair system for 784 kbit/s (concluded)** + +| Time | Frame Bit # | HOH Bit # | Abrv. name | Full name | Notes | +|------------------------|-------------|-----------|------------|---------------------------|---------------------------------------| +| | 3536 | 44 | indic/indr | ready to receive | indic = LTU → NTU
indr = NTU → LTU | +| | 3537 | 45 | uib | unspecified indicator bit | | +| | 3538 | 46 | uib | unspecified indicator bit | | +| $6 - \frac{1}{392}$ ms | 3539-4702 | – | B37-B48 | payload blocks 37-48 | HDSL payload | +| | 4703 | 47 | stq1s | stuff quat 1 sign | Frame stuffing | +| 6 ms nominal | 4704 | 48 | stq1m | stuff quat 1 magnitude | Frame stuffing | +| | 4705 | 49 | stq2s | stuff quat 2 sign | Frame stuffing | +| $6 + \frac{1}{392}$ ms | 4706 | 50 | stq2m | stuff quat 2 magnitude | Frame stuffing | + +## ANNEX B + +### High bit rate Digital Subscriber Line (HDSL) CAP based system + +#### B.1 Scope and general information + +##### B.1.1 Scope + +This annex describes HDSL systems using Carrierless Amplitude Phase modulation (CAP) for metallic local lines that provide transport for the same applications discussed in the body of this Recommendation. Individual systems transport net bit rates of 1168 kbit/s or 2320 kbit/s. Two 1168 kbit/s systems are used for the support of bit rates at the 2048 kbit/s hierarchical level for different types of applications associated with this bit rate. Common circuitry for combining and controlling two 1168 kbit/s HDSL systems is described. One 2320 kbit/s system supports bit rates at the 2048 kbit/s hierarchical level. + +The requirements for the individual HDSL transmission system, the transmission medium, the transmission performance and the HDSL maintenance and procedures are defined in this annex. The common circuitry and the HDSL transceivers that form the common core, are defined in this Recommendation. The core is generally independent of applications. + +The scope of this annex is in general the same as the scope, clause 1, of the body of this Recommendation. Many provisions in this Recommendation are line-code independent. Such provisions are not repeated in this annex, only a reference to the corresponding provisions in the body of this Recommendation is included. + +#### B.2 References + +See clause 2 for references. + +#### B.3 Abbreviations + +See clause 3 for abbreviations. + +## **B.4 Reference configuration and functional description** + +See clause 4 for the reference configuration and functional description. However, this annex focuses on HDSL transmission systems that use only one or two-pairs. + +The provisions in this annex are aimed at interoperability of equipment from different vendors. + +## **B.5 HDSL core specification** + +### **B.5.1 Functions** + +See 5.1 for functions necessary for the correct operation of the HDSL core. + +### **B.5.2 Transmission medium** + +See 5.2 for descriptions of the transmission medium, including noise and micro interruptions. However, for testing CAP-based HDSL systems, additional artificial noise that simulates NEXT is defined in B.6 as are requirements for CAP-based HDSL systems, concerning performance in the presence of, or concerning, the susceptibility to the various impairments associated with the transmission medium. + +### **B.5.3 Transmission method** + +#### **B.5.3.1 General** + +See 5.3.1 for a general description of the transmission method. + +#### **B.5.3.2 Transmission on one-pair** + +Transmission on one DLL is provided by HDSL transceivers operating at 2320 kbit/s and using the CAP line code in accordance with Figure 4 and Figures B.2, B.3 and B.4 and associated description. + +#### **B.5.3.3 Transmission on two-pairs** + +Transmission on two DLLs is provided by two parallel HDSL transceivers, each operating at 1168 kbit/s and using the CAP line code in accordance with Figure 4 and Figures B.2, B.3 and B.4 and associated description. + +#### **B.5.3.4 Transmission on three or four-pairs** + +The transmission of the complete core frame on three or four-pairs is not excluded, but is not treated in this annex. + +#### **B.5.3.5 Line code** + +The line code shall be trellis-coded Carrierless Amplitude Phase modulation (CAP) with Tomlinson precoding [B3]. Trellis-coded 64-CAP and 128-CAP shall be used for 1168 kbit/s and 2320 kbit/s transceivers, respectively. An uncoded 64-CAP signal constellation (signal space diagram) is shown in Figure B.1 (the LSB is received first). The uncoded mode is used during "start up" as described in B.5.6. The 2D (2 dimensional) 8-state trellis code [B1] (without the differential feature) shall be used. Of the 6 bit/symbol of 64-CAP and the 7 bit/symbol of 128-CAP, all bits except one are information bits. One bit of redundancy is added by the 2D 8-state code. Coded 64-CAP and 128-CAP signal constellations (signal space diagrams) are shown in Figure B.3 a) and Figure B.3 b), respectively. For each system, the scrambled data stream to be transmitted is divided into groups, the LSB of which is the first to be received. + +The bit stream entering each "H" (HDSL transceiver) block of Figure 1 or 2, shall be scrambled as defined in B.5.3.4.2. + +![Figure B.1/G.991.1 – Uncoded 64-CAP signal constellation. The figure shows an 8x8 grid of points representing a 64-CAP constellation. Each point is labeled with a 6-bit binary code (Z5 Z4 Z3 Z2 Z1 Z0).](4e525151b89a2f87f31d869491a817d8_img.jpg) + +| Y \ X | -7 | -5 | -3 | -1 | +1 | +3 | +5 | +7 | +|-------|--------|--------|--------|--------|--------|--------|--------|--------| +| +7 | 011010 | 011011 | 011001 | 011000 | 001000 | 001001 | 001011 | 001010 | +| +5 | 011110 | 011111 | 011101 | 011100 | 001100 | 001101 | 001111 | 001110 | +| +3 | 010110 | 010111 | 010101 | 010100 | 000100 | 000101 | 000111 | 000110 | +| +1 | 010010 | 010011 | 010001 | 010000 | 000000 | 000001 | 000011 | 000010 | +| -1 | 110010 | 110011 | 110001 | 110000 | 100000 | 100001 | 100011 | 100010 | +| -3 | 110110 | 110111 | 110101 | 110100 | 100100 | 100101 | 100111 | 100110 | +| -5 | 111110 | 111111 | 111101 | 111100 | 101100 | 101101 | 101111 | 101110 | +| -7 | 111010 | 111011 | 111001 | 111000 | 101000 | 101001 | 101011 | 101010 | + +Figure B.1/G.991.1 – Uncoded 64-CAP signal constellation. The figure shows an 8x8 grid of points representing a 64-CAP constellation. Each point is labeled with a 6-bit binary code (Z5 Z4 Z3 Z2 Z1 Z0). + +T1529230-98 + +**Figure B.1/G.991.1 – Uncoded 64-CAP signal constellation +(code point designations are Z0 ... Z5)** + +### **B.5.3.5.1 Trellis encoding/decoding** + +#### **B.5.3.5.1.1 64 point constellation – two-pair system** + +The scrambled data stream to be transmitted is divided into groups of five consecutive bits (LSB received first) each to be transmitted in a symbol. As shown in Figure B.2, the first two bits of a group, $I1_n$ and $I2_n$ , where $n$ designates the sequence number of the group and $I1_n$ is the LSB are input to a systematic convolutional encoder. It generates redundant bit $Y0_n$ . This redundant bit, $Y0_n$ , and the bits $I1_n$ through $I5_n$ become bits designated $Z0_n$ through $Z5_n$ . These bits are fed into the 64-state, bit-to-symbol mapping function. Each group of bits maps to a point in the signal constellation shown in Figure B.3 a). The trellis is shown in Figure B.4. + +![Block diagram of a 2D 8-state trellis encoder. The diagram shows a systematic convolutional encoder with feedback. Inputs I1_n and I2_n enter the encoder. The encoder generates a redundant bit Y0_n and passes through bits I3_n, I4_n, I5_n, and I6_n. The output bits are Z0_n, Z1_n, Z2_n, Z3_n, Z4_n, Z5_n, and Z6_n. The encoder consists of two stages. The first stage takes I1_n and I2_n, performs modulo-2 addition, and then passes the result through a symbol interval block 'T'. The output of 'T' is then added to the feedback signal. The second stage takes the output of the first stage, performs modulo-2 addition, and then passes it through another symbol interval block 'T'. The output of this 'T' block is Y0_n. The feedback signal is generated by taking Y0_n, performing modulo-2 addition with the output of the first 'T' block, and then passing it through an AND gate. The output of the AND gate is then added to the output of the second 'T' block. The final output is Z0_n. The other output bits Z1_n through Z6_n are derived from the input bits I1_n through I6_n and the redundant bit Y0_n. A legend at the bottom left defines the symbols: a circle with a cross for modulo-2 addition and a 'T' for symbol interval.](a37adbbe12ec735a20ead2466363d07a_img.jpg) + +16-Z6 applicable to 128 point constellation only + +$\oplus$ Modulo 2 addition, logical exclusive or + T Symbol interval or $(1/233\ 80\ \text{kbit/s})\ 4.281\ \mu\text{s}$ + +T1529240-98 + +Block diagram of a 2D 8-state trellis encoder. The diagram shows a systematic convolutional encoder with feedback. Inputs I1\_n and I2\_n enter the encoder. The encoder generates a redundant bit Y0\_n and passes through bits I3\_n, I4\_n, I5\_n, and I6\_n. The output bits are Z0\_n, Z1\_n, Z2\_n, Z3\_n, Z4\_n, Z5\_n, and Z6\_n. The encoder consists of two stages. The first stage takes I1\_n and I2\_n, performs modulo-2 addition, and then passes the result through a symbol interval block 'T'. The output of 'T' is then added to the feedback signal. The second stage takes the output of the first stage, performs modulo-2 addition, and then passes it through another symbol interval block 'T'. The output of this 'T' block is Y0\_n. The feedback signal is generated by taking Y0\_n, performing modulo-2 addition with the output of the first 'T' block, and then passing it through an AND gate. The output of the AND gate is then added to the output of the second 'T' block. The final output is Z0\_n. The other output bits Z1\_n through Z6\_n are derived from the input bits I1\_n through I6\_n and the redundant bit Y0\_n. A legend at the bottom left defines the symbols: a circle with a cross for modulo-2 addition and a 'T' for symbol interval. + +**Figure B.2/G.991.1 – 2D 8-state trellis encoder** + +**B.5.3.5.1.2 128 point constellation – one-pair system** + +The scrambled data stream to be transmitted is divided into groups of six consecutive bits (LSB received first) each to be transmitted in a symbol. As shown in Figure B.2, the first two bits of a group, $I1_n$ and $I2_n$ , where $n$ designates the sequence number of the group and $I1_n$ is the LSB are input to a systematic convolutional encoder. It generates redundant bit $Y0_n$ . This redundant bit, $Y0_n$ , and the bits $I1_n$ , through $I6_n$ become bits designated $Z0_n$ through $Z6_n$ . These bits are fed into the 128-state, bit-to-symbol mapping function. Each group of bits map to a point in the signal constellation shown in Figure B.3 b). The trellis is shown in Figure B.4. + +![Coded 64-AP constellation diagram showing 64 points arranged in an 8x8 grid. The points are labeled with 5-bit binary sequences. The vertical axis is labeled with values +7, +5, +3, +1, -1, -3, -5, -7. The horizontal axis is labeled with values -7, -5, -3, -1, +1, +3, +5, +7. A small text 'T1529250-98' is at the bottom right.](23f62df20874b7423cbf7f29fcecf9ed_img.jpg) + +T1529250-98 + +Coded 64-AP constellation diagram showing 64 points arranged in an 8x8 grid. The points are labeled with 5-bit binary sequences. The vertical axis is labeled with values +7, +5, +3, +1, -1, -3, -5, -7. The horizontal axis is labeled with values -7, -5, -3, -1, +1, +3, +5, +7. A small text 'T1529250-98' is at the bottom right. + +a) Coded 64-AP constellation (code point designations are Z5 ... Z0) + +![Coded 128-CAP constellation diagram showing 128 points arranged in a grid. The points are labeled with 7-bit binary sequences. The vertical axis is labeled with values 15, 13, 10, 9, 7, 5, 3, 1, -1, -3, -5, -7, -9, -11, -13, -15. The horizontal axis is labeled with values -13, -9, -5, -1, 1, 3, 7, 11, 15. A small text 'T1529260-98' is at the bottom right.](1ef2b5e267d1196dd7375ea783d5ff59_img.jpg) + +T1529260-98 + +Coded 128-CAP constellation diagram showing 128 points arranged in a grid. The points are labeled with 7-bit binary sequences. The vertical axis is labeled with values 15, 13, 10, 9, 7, 5, 3, 1, -1, -3, -5, -7, -9, -11, -13, -15. The horizontal axis is labeled with values -13, -9, -5, -1, 1, 3, 7, 11, 15. A small text 'T1529260-98' is at the bottom right. + +b) Coded 128-CAP constellation (code point designations are Z6 ... Z0) + +Figure B.3/G.991.1 – Signal constellations with Trellis coding + +![Trellis diagram showing state transitions between 8 states. The diagram consists of two columns of 8 nodes each. Between the columns are four intermediate nodes labeled A, B, C, and D. Every node in the first column is connected to every node in the second column via a path through one of the intermediate nodes A, B, C, or D. This represents a fully connected transition between current and next states.](9faa3512b2ff7973283e76192e91bf65_img.jpg) + +| Subset | Current State | | | | Next State | | | +|--------|---------------|-----|-----|--|------------|---------|---------| +| | W1n | W2n | W3n | | W1n + 1 | W2n + 1 | W3n + 1 | +| ABDC | 0 | 0 | 0 | | 0 | 0 | 0 | +| DCAB | 0 | 0 | 1 | | 0 | 0 | 1 | +| HGFE | 0 | 1 | 0 | | 0 | 1 | 0 | +| EFGH | 0 | 1 | 1 | | 0 | 1 | 1 | +| BACD | 1 | 0 | 0 | | 1 | 0 | 0 | +| CDBA | 1 | 0 | 1 | | 1 | 0 | 1 | +| GHEF | 1 | 1 | 0 | | 1 | 1 | 0 | +| FEHG | 1 | 1 | 1 | | 1 | 1 | 1 | + +T1529270-98 + +Trellis diagram showing state transitions between 8 states. The diagram consists of two columns of 8 nodes each. Between the columns are four intermediate nodes labeled A, B, C, and D. Every node in the first column is connected to every node in the second column via a path through one of the intermediate nodes A, B, C, or D. This represents a fully connected transition between current and next states. + +**Figure B.4/G.991.1 – Trellis diagram of 2D 8-state code** + +**B.5.3.5.2 Scrambling method** + +The scrambler/descrambler, included in each transceiver, shall be different in both directions of transmission. The generating polynomials shall be as follows: + +Customer premises transceiver (NTU) = $1 \oplus x^{-18} \oplus x^{-23}$ . + +Exchange transceiver (LTU) = $1 \oplus x^{-5} \oplus x^{-23}$ . + +The scramblers and descramblers are shown in Figure B.5 as they operate during start up: the self-synchronizing mode. At the transmitter, the scrambler shall effectively divide (modulo 2) the bits sequence by the generating polynomial. The coefficients of the quotients of this division, taken in descending order, form the data sequence that appears at the output of the data scrambler. At the receiver, the received bit sequence shall be multiplied (modulo 2) by the polynomial to recover the original bit stream. + +![Diagram a) LTU transmit scrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the first delay is added to the feedback signal at the second summing junction. The output of the third delay is labeled x^-5. The final output is labeled x^-23.](3a006a7c9c9934695f0fc731344eff8a_img.jpg) + +Diagram a) LTU transmit scrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the first delay is added to the feedback signal at the second summing junction. The output of the third delay is labeled x^-5. The final output is labeled x^-23. + +a) LTU transmit scrambler + +![Diagram b) LTU receive descrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the second delay is labeled x^-18. The output of the third delay is added to the feedback signal at the second summing junction. The final output is labeled x^-23.](56a42b3c4e1a79a71c8f27aa03b78b84_img.jpg) + +Diagram b) LTU receive descrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the second delay is labeled x^-18. The output of the third delay is added to the feedback signal at the second summing junction. The final output is labeled x^-23. + +b) LTU receive descrambler + +![Diagram c) NTU transmit scrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the second delay is labeled x^-18. The output of the third delay is added to the feedback signal at the second summing junction. The final output is labeled x^-23.](51167ecef86d85cdc6dde05a3afb74b8_img.jpg) + +Diagram c) NTU transmit scrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the second delay is labeled x^-18. The output of the third delay is added to the feedback signal at the second summing junction. The final output is labeled x^-23. + +c) NTU transmit scrambler + +![Diagram d) NTU receive descrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the second delay is labeled x^-5. The output of the third delay is added to the feedback signal at the second summing junction. The final output is labeled x^-23.](7472c67897a35ed6b67fcb47ea4c6b6c_img.jpg) + +Diagram d) NTU receive descrambler. It shows a feedback loop with four delay elements labeled x^-1. The input Din is added to the feedback signal at the first summing junction. The output of the second delay is labeled x^-5. The output of the third delay is added to the feedback signal at the second summing junction. The final output is labeled x^-23. + +T1529280-98 + +d) NTU receive descrambler + +**Figure B.5/G.991.1 – CAP HDSL scrambler/descrambler start-up mode** + +During data transfer the scramblers are locked and the scrambled sequence is added (modulo 2) at the transmitter and subtracted (modulo 2) at the receiver as indicated in Figure B.6. As explained in B.5.6.5.4, the transfer from the self-synchronizing mode to the locked mode occurs with the transmit data being all ONEs, and the transfer to locked mode does not require synchronization of the transfer at both ends. + +Note that all bits in the HDSL frame, including overhead, sync word and stuffing bits, are scrambled. + +![Block diagram of an LTU transmit scrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout.](21ea5add6a61cc951b5c43ddffefb3ff_img.jpg) + +Block diagram of an LTU transmit scrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout. + +a) LTU transmit scrambler + +![Block diagram of an LTU receive descrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout.](cf36ccd7ff79531e18e5b0ab1f0c46d4_img.jpg) + +Block diagram of an LTU receive descrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout. + +b) LTU receive descrambler + +![Block diagram of an NTU transmit scrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout.](e26bb66586e464339df27951d5c9355e_img.jpg) + +Block diagram of an NTU transmit scrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout. + +c) NTU transmit scrambler + +![Block diagram of an NTU receive descrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout.](5a01395925fc88802da68fb5ac0f31ff_img.jpg) + +Block diagram of an NTU receive descrambler. The input Din is summed with a feedback signal at a summer. The output of this summer is inverted by an INV block and then passed through a series of delay blocks (x^-1). The output of the final delay block is labeled x^-23 and is fed back through another summer to produce the final output Dout. + +d) NTU receive descrambler + +T1529290-98 + +**Figure B.6/G.991.1 – CAP HDSL scrambler/descrambler – data mode** + +### B.5.3.6 Line symbol rate + +The symbol rate shall be in the range of: + +- 1168 kbit/s transceiver: 233.60 kbaud $\pm$ 110 ppm +- 2320 kbit/s transceiver: 386.667 kbaud $\pm$ 90 ppm. + +### B.5.4 Frame structure + +#### B.5.4.1 Core frame + +See 5.4.1 for a description of the core frame. + +#### B.5.4.2 HDSL frame + +This subclause describes the proposed HDSL frame structure in the binary format before scrambling and encoding. This structure is valid during normal operation after symbol timing synchronization, frame alignment and after all internal transceiver coefficients have stabilized sufficiently to permit a reliable transport of the signals through the HDSL transceiver systems. Except for the provision of stuffing bits and the 14 bit sync word, the frame is the same as described in 5.4.2. + +The nominal HDSL frame length is 6 ms. + +- The mean length of the HDSL frame for the two-pair system is 7008 bits in 6 ms. But each individual frame contains either 0, 1 or 2 stuffing bit pairs, which gives a real length of 7006 bits in $6 - \frac{1}{584}$ ms, 7008 bits in 6 ms, or 7010 bits in $6 + \frac{1}{584}$ ms. +- The mean length of the HDSL frame for the one-pair system is 13 920 bits in 6 ms. But each individual frame contains either 0, 1, or 2 stuffing bit pairs, which gives a real length of 13 918 bits in $6 - \frac{2}{2320}$ ms or 13 922 bits in $6 + \frac{2}{2320}$ ms. +- The bit assignment in each HDSL frame in each direction of transmission for all pairs is shown in Table B.1 and Table 4. +- The HDSL transceiver systems shall each independently accommodate differences in the bit timing of the two directions of transmission, or of the application data and the HDSL transceiver system by including none, one or two stuffing bit pairs at the end of the HDSL frame. +- In the LTU, the clock rate of the two different HDSL frames shall be derived from the same source. The location of the sync word, i.e. the start of the HDSL frames in the different pairs shall be synchronized to each other. The maximum differential delay between the start of the frames shall be less than one symbol period, measured at the line interface of each HDSL transceiver. +- The inclusion of stuffing bit pairs, if necessary, for a two-pair system, shall be identical for both pairs. + +##### B.5.4.2.1 HDSL frame structure + +###### B.5.4.2.1.1 Frame structure for two-pair system + +Figure B.7 illustrates the HDSL frame structure for two-pair systems, which is composed of framing bits and bytes and the mapping of the core frame bytes to it. The frame is subdivided into four groups. The first group of the frame starts with the 14 bits long synchronization word followed by two HDSL overhead bits and twelve blocks of HDSL payload, each consisting of 145 bits, containing one overhead-bit $Z_{mn}$ and eighteen bytes of the core frame. The $Z_{mn}$ -bits ( $m = 1, 2$ indicates bits on one of the two-pairs; $n = 1 \dots 48$ is the running number of the HDSL payload block in the frame) provide an additional overhead channel, for which forty-eight bits per frame of each HDSL transceiver system at a capacity of 8 kbit/s are available. + +![Diagram of HDSL two-pair system frame structure showing timing and bit layout.](bd33d5bc49161429f4c7da76529bcd18_img.jpg) + +The diagram illustrates the HDSL two-pair system frame structure. At the top, three horizontal lines represent different frame durations: + + +- 7010 bits, $(6 + \frac{2}{1168})$ ms +- 7008 bits, 6 ms +- 7006 bits, $(6 - \frac{2}{1168})$ ms + + Below this, a detailed bit layout is shown. The frame starts with a 'Sync word' (14 bits) and is flanked by 'Stuff Bit Pairs' (SBP). The main body consists of 10 groups of overhead bits (HOH) and payload blocks. Each HOH group contains 10 bits (B, H, B, H, B, H, B, H, B, H). The payload blocks are organized into two rows: + + +- Row 1: Z1, Byte 1, Byte 3, Byte 5, Byte 7, Byte 9, Byte 11, ..., Byte 25, Byte 27, Byte 29, Byte 31, Byte 33, Byte 35 +- Row 2: Z2, Byte 2, Byte 4, Byte 6, Byte 8, Byte 10, Byte 12, ..., Byte 26, Byte 28, Byte 30, Byte 32, Byte 34, Byte 36 + + This section is labeled 'HDSL Payload Block (48 per HDSL Frame)'. The total duration of the frame is marked as 6 ms, with specific timing markers at 0 ms and $(6 - \frac{2}{1168})$ ms. A '145 bits' duration is also indicated at the bottom. The diagram is labeled T1529300-98. + +Diagram of HDSL two-pair system frame structure showing timing and bit layout. + +| Symbol | Name, Function | +|----------------------------------|-------------------------------------------------------------------------| +| B01 to B48 | HDSL system payload blocks | +| Byte n, (n = 1 ... 144) | Byte n from core frame | +| HOH | HDSL overhead (sw, eoc, crc, ...) | +| SBP | Stuff Bit Pair | +| Sync Word | 7-symbol Barker codes, "double Barker" → 14 bits | +| Z n
(n = 1 ... 48) | Additional overhead bits (Z-bits)
indicating number of payload block | + +**Figure B.7/G.991.1 – HDSL two-pair system frame structure** + +The first eight Z-bits ( $Z_{m1} \dots Z_{m8}$ ) are reserved for core applications and presently set to ONE. + +The Z-bits No. 9 ... 48 ( $Z_{m9} \dots Z_{m48}$ ) are application dependent and are transparently transported through the core. The use of these bits shall be described in the application specific requirements. Unused bits shall be set to ONE. + +The three groups following the first group have an equal structure. Each consists of ten HDSL overhead bits and twelve HDSL payload blocks as described above. So one frame contains a synchronization word, 32 HDSL overhead bits, 48 Z-bits and 864 bytes of the core frame. + +Provision is included at the end of the frame for the possibility of 4 stuffing bits. One stuffing bit pair is normally included. This bit pair may be deleted or one additional stuffing bit pair may be inserted, depending on the relation of the timing. The algorithm for determining whether to add or delete stuffing bit pairs shall provide a window of at least 2 unit intervals (at the 2048 kbit/s rate), in the relative phase of the HDSL and 2048 kbit/s sequences, within which the stuffing bits will neither be added nor deleted. The length of the HDSL frame is nominally 7008 bits or 6 ms (for the nominal + +HDSL clock frequency), or either 7010 bits, which equals $6 + \frac{2}{1168}$ ms or 7006 bits corresponding to $6 - \frac{2}{1168}$ ms. The receiver is able to evaluate the length of an incoming frame by detection of the sync word in the following frame and to adjust the demultiplexing of the data stream. + +#### B.5.4.2.1.2 Frame structure for one-pair system + +Figure B.8 illustrates the HDSL frame structure and shows the mapping of the core frame bytes to it. As for the two-pair structure, the frame is subdivided into four groups. The first group of the frame starts with the 14 bits long synchronization word followed by two HDSL overhead bits and twelve blocks of HDSL payload, each consisting of 289 bits, containing one overhead bit $Z_n$ and thirty six bytes of the core frame. The $Z_n$ -bits ( $n = 1 \dots 48$ is the running number of the HDSL payload block in the frame) provide an additional overhead channel, for which forty-eight bits of each HDSL frame, a capacity of 8 kbit/s, are available. + +![Diagram of HDSL one-pair system frame structure showing bit timing and payload mapping.](e18841eb4a995df8354a793459e12fd0_img.jpg) + +The diagram illustrates the HDSL frame structure for a one-pair system. It shows the timing and bit composition of the frame. + +- Timing:** + - The total frame duration is 13 922 bits, which equals $(6 + \frac{2}{2320})$ ms. + - A shorter duration of 13 920 bits, which equals 6 ms, is also indicated. + - Another duration of 13 918 bits, which equals $(6 - \frac{2}{2320})$ ms, is shown. + - Timing markers are placed at 0 ms and 6 ms. + - Intervals of $(6 - \frac{2}{2320})$ ms and $(6 + \frac{2}{2320})$ ms are indicated between the 6 ms mark and the start/end of the frame. +- Bit Composition:** + - The frame starts with a 14-bit **Sync word**. + - This is followed by a 2-bit **HOH** (HDSL overhead) section, containing bits **H** and **B**. + - There are four groups of payload blocks, each containing 3468 bits. + - Between these groups are 10-bit sections containing bits **B**, **H**, and **B**. + - The frame ends with a 2-bit **SBP** (stuff bit pair) section, containing bits **S**, **B**, and **P**. +- HDSL Payload Block:** + - Each payload block consists of 289 bits. + - It starts with a **Zn** bit (Additional overhead bit). + - It contains 36 bytes of core frame data: **Byte 1** through **Byte 36**. + - There are 48 such payload blocks per HDSL frame. + +Diagram of HDSL one-pair system frame structure showing bit timing and payload mapping. + +| Symbol | Name, Function | +|----------------------|-------------------------------------------------------------| +| B01 to B48 | HDSL system payload blocks | +| Byte n | Byte n from core frame ( $n = 1 \dots 144$ ) | +| HOH | HDSL overhead (sw, eoc, crc, ...) | +| SBP | stuff bit pair | +| Sync Word | 7-symbol Barker codes, "double Barker" $\rightarrow$ 14bits | +| $Z_n$ | Additional overhead bits (Z-bits) | +| ( $n = 1 \dots 48$ ) | indicating number of payload block | + +Figure B.8/G.991.1 – HDSL one-pair system frame structure + +The first eight Z-bits ( $Z_1 \dots Z_8$ ) are reserved for core applications and presently set to ONE. + +The Z-bits No. 9 ... 48 ( $Z_9 \dots Z_{48}$ ) are application dependent and are transparently transported through the core. The use of these bits shall be described in the application specific requirements. Unused bits shall be set to ONE. + +The three groups, following the first group, have an equal structure. Each consists of ten HDSL overhead bits and twelve HDSL payload blocks as described above. So one frame contains a synchronization word, 32 HDSL overhead bits, 48 Z-bits and 1728 bytes of the core frame. + +Provision is included at the end of the frame for the possibility of four stuffing bits. One stuffing bit pair is normally included. This bit pair may be deleted or one additional stuffing bit pair may be inserted, depending on the relation of the phase of the input bit stream and the transceiver clock. The algorithm for determining whether to add or delete stuffing bit pairs shall provide a window of at least 2 unit intervals (at the 2048 kbit/s rate), in the relative phase of the HDSL and 2048 kbit/s sequences, within which the stuffing bits will neither be added nor deleted. The length of the HDSL frame is nominally 13 920 bits or 6 ms (for the nominal HDSL clock frequency), or either 13 922 bits, which equals $6 + \frac{2}{2320}$ ms or 13 918 bits corresponding to $6 - \frac{2}{2320}$ ms. The receiver is able to evaluate the length of an incoming frame by detection of the sync word in the following frame and to adjust the demultiplexing of the data stream. + +#### B.5.4.2.2 HDSL frame bit assignments + +Table B.1 and Table 2 present the bit sequences of the HDSL frames prior to scrambling at the transmit and after descrambling at the receive side. While the frame structures are identical in both directions of transmission, the functional assignments of individual bits in the direction LTU-to-NTU or NTU-to-LTU are different. Unused bits in either direction are set to ONE. For example, the proposed NTU power status bits are defined only in the frame transmitted towards the LTU and the corresponding bit positions in the reverse direction have no assignment. The bit assignments are identical for each of the pairs. The bit assignments in Table B.1 are nearly the same as in Table 4 and most of the bit descriptions given in 5.4.2.2 are applicable. + +**Table B.1/G.991.1 – HDSL two-pair system frame structure** + +| Time | Frame Bit # | HOH Bit # | Abrv. name | Full name | Notes | +|-------------|--------------------|------------------|-------------------|------------------------------------------------------------|----------------------------------------------------------| +| 0 ms | 1-14 | 1-14 | SW 1-14 | sync word | Double Barker Code | +| | 15 | 15 | losd | loss of input signal at the far end applications interface | | +| | 16 | 16 | febe | far end block error | | +| | 17-1756 | – | B01-B12 | payload block 1-12 | HDSL payload including Zm 1 -Zm 12 | +| | 1757 | 17 | eoc01 | eoc address | | +| | 1758 | 18 | eoc02 | eoc address | | +| | 1759 | 19 | eoc03 | eoc data/opcode | | +| | 1760 | 20 | eoc04 | eoc odd/even byte | | +| | 1761 | 21 | crc 1 | cyclic redundancy check | CRC-6 | +| | 1762 | 22 | crc 2 | cyclic redundancy check | CRC-6 | +| | 1763 | 23 | ps1 | NTU power status bit 1 | NTU → LTU only | +| | 1764 | 24 | ps2 | NTU power status bit 2 | NTU → LTU only | +| | 1765 | 25 | bpv | bipolar violation | | +| | 1766 | 26 | eoc05 | eoc unspecified | | + +**Table B.1/G.991.1 – HDSL two-pair system frame structure (concluded)** + +| Time | Frame Bit # | HOH Bit # | Abrv. name | Full name | Notes | +|-------------------------|-------------|-----------|------------|---------------------------------|-----------------------------------------------------------| +| | 1767-3506 | – | B13-B24 | payload blocks 13-24 | HDSL Payload including Zm 13 -Zm 24 | +| | 3507 | 27 | eoc06 | eoc message bit 1 | | +| | 3508 | 28 | eoc07 | eoc message bit 2 | | +| | 3509 | 29 | eoc08 | eoc message bit 3 | | +| | 3510 | 30 | eoc09 | eoc message bit 4 | | +| | 3511 | 31 | crc3 | cyclic redundancy check | CRC-6 | +| | 3512 | 32 | crc4 | cyclic redundancy check | CRC-6 | +| | 3513 | 33 | hrp | regenerator present | LTU ← REG → NTU | +| | 3514 | 34 | rrbe | regenerator remote block error | LTU ← REG → NTU | +| | 3515 | 35 | rcbe | regenerator central block error | LTU ← REG → NTU | +| | 3516 | 36 | repa | regenerator alarm | | +| | 3517-5256 | – | B25-B36 | payload blocks 25-36 | HDSL payload including Zm 25 -Zm 36 | +| | 5257 | 37 | eoc10 | eoc message bit 5 | | +| | 5258 | 38 | eoc11 | eoc message bit 6 | | +| | 5259 | 39 | eoc12 | eoc message bit 7 | | +| | 5260 | 40 | eoc13 | eoc message bit 8 | | +| | 5261 | 41 | crc5 | cyclic redundancy check | CRC-6 | +| | 5262 | 42 | crc6 | cyclic redundancy check | CRC-6 | +| | 5263 | 43 | rta | remote terminal alarm | NTU → LTU only | +| | 5264 | 44 | indic/indr | ready to receive | indic = LTU → NTU
indr = NTU → LTU | +| | 5265 | 45 | uib | unspecified indicator bit | | +| | 5266 | 46 | uib | unspecified indicator bit | | +| $6 - \frac{2}{1168}$ ms | 5267-7006 | – | B37-B48 | payload blocks 37-48 | HDSL payload including Zm 37 -Zm 48 | +| | 7007 | 47 | stb1a | stuff bit 1a | frame stuffing | +| 6 ms nominal | 7008 | 48 | stb1b | stuff bit 1b | frame stuffing | +| | 7009 | 49 | stb2a | stuff bit 2a | frame stuffing | +| $6 + \frac{2}{1168}$ ms | 7010 | 50 | stb2b | stuff bit 2b | frame stuffing | + +**Table B.2/G.991.1 – HDSL one-pair system frame structure** + +| Time | Frame Bit # | HOH Bit # | Abbr. name | Full name | Notes | +|------|-------------|-----------|------------|------------------------------------------------------------|-----------------------------------------------------------| +| 0 ms | 1-14 | 1-14 | SW 1-14 | sync word | Double Barker Code | +| | 15 | 15 | losd | loss of input signal at the far end applications interface | | +| | 16 | 16 | febe | far end block error | | +| | 17-3484 | – | B01-B12 | payload block 1-12 | HDSL payload including Zm 1 -Zm 12 | +| | 3485 | 17 | eoc01 | eoc address | | +| | 3486 | 18 | eoc02 | eoc address | | +| | 3487 | 19 | eoc03 | eoc data/opcode | | +| | 3488 | 20 | eoc04 | eoc odd/even byte | | +| | 3489 | 21 | crc 1 | cyclic redundancy check | CRC-6 | +| | 3490 | 22 | crc 2 | cyclic redundancy check | CRC-6 | +| | 3491 | 23 | ps1 | NTU power status bit 1 | NTU → LTU only | +| | 3492 | 24 | ps2 | NTU power status bit 2 | NTU → LTU only | +| | 3493 | 25 | bpv | bipolar violation | | +| | 3494 | 26 | eoc05 | eoc unspecified | | +| | 3495-6962 | – | B13-B24 | payload blocks 13-24 | HDSL payload including Zm 13 -Zm 24 | +| | 6963 | 27 | eoc06 | eoc message bit 1 | | +| | 6964 | 28 | eoc07 | eoc message bit 2 | | +| | 6965 | 29 | eoc08 | eoc message bit 3 | | +| | 6966 | 30 | eoc09 | eoc message bit 4 | | +| | 6967 | 31 | crc3 | cyclic redundancy check | CRC-6 | +| | 6968 | 32 | crc4 | cyclic redundancy check | CRC-6 | +| | 6969 | 33 | hrp | regenerator present | LTU ← REG → NTU | +| | 6970 | 34 | rrbe | regenerator remote block error | LTU ← REG → NTU | +| | 6971 | 35 | rcbe | regenerator central block error | LTU ← REG → NTU | +| | 6972 | 36 | repa | regenerator alarm | | +| | 6973-10 440 | – | B25-B36 | payload blocks 25-36 | HDSL payload including Zm 25 -Zm 36 | +| | 10 441 | 37 | eoc10 | eoc message bit 5 | | +| | 10 442 | 38 | eoc11 | eoc message bit 6 | | +| | 10 443 | 39 | eoc12 | eoc message bit 7 | | +| | 10 444 | 40 | eoc13 | eoc message bit 8 | | +| | 10 445 | 41 | crc5 | cyclic redundancy check | CRC-6 | +| | 10 446 | 42 | crc6 | cyclic redundancy check | CRC-6 | + +**Table B.2/G.991.1 – HDSL one-pair system frame structure (concluded)** + +| Time | Frame Bit # | HOH Bit # | Abbr. name | Full name | Notes | +|-------------------------|-------------------|-----------|------------|---------------------------|--------------------------------------------------------------| +| | 10 447 | 43 | rta | remote terminal alarm | NTU → LTU only | +| | 10 448 | 44 | indc/indr | ready to receive | indc = LTU → NTU
indr = NTU → LTU | +| | 10 449 | 45 | uib | unspecified indicator bit | | +| | 10 450 | 46 | uib | unspecified indicator bit | | +| $6 - \frac{2}{2320}$ ms | 10 451-
13 918 | – | B37-B48 | payload blocks 37-48 | HDSL payload
including Z m37 -Z m48 | +| | 13 919 | 47 | stb1a | stuff bit 1a | frame stuffing | +| 6 ms nominal | 13 920 | 48 | stb1b | stuff bit 1b | frame stuffing | +| | 13 921 | 49 | stb2a | stuff bit 2a | frame stuffing | +| $6 + \frac{2}{2320}$ ms | 13 922 | 50 | stb2b | stuff bit 2b | frame stuffing | + +The following are brief descriptions of the currently defined overhead bits that are different from those defined in 5.4.2.2: + +stb (stuffing bit pairs; stb1a, stb1b and stb2a, stb2b) + +These bits are always used in pairs. This means either none, two (stb1a, stb1b) or four (stb1a, stb1b and stb2a, stb2b) stuffing bits are inserted, depending on the relation of the phase of the input bit stream and the bit clock synchronized to the transceiver(s). There should be a relative phase range of $\pm 2$ bit intervals during which two stuffing bits (stb1a, stb1b) are transmitted. + +### **B.5.5 HDSL embedded operations channel (eoc)** + +See 5.5 for requirements for the embedded operations channel. The only departure from the description in 5.5 is the use of the term "signal quality" (SQ) in this annex instead of "noise margin", see 5.5.7. SQ more accurately describes the measurement involved. + +#### **B.5.5.1 Signal quality** + +The requirements in this subclause are the same as in 5.5.7 except that the measurement referred to here is Signal Quality (SQ). The purpose of SQ is the same as that for noise margin in 5.5.7. + +### **B.5.6 Start-up procedure** + +#### **B.5.6.1 General** + +##### **B.5.6.1.1 Start-up** + +See 5.6.1.1 for a description of start-up. + +##### **B.5.6.1.2 Activation of HDSL transceiver pairs** + +See 5.6.1.2 for activation of HDSL transceiver pairs. + +### **B.5.6.1.3 Transparency** + +Prior to the completion of activation, transmission is not transparent, the signals that are present at the line interfaces of the HDSL transceivers are special start-up patterns generated by the HDSL transceivers. Each HDSL transceiver shall provide transparent transmission of data to the core function after the termination of the individual activation procedure. The output signal of receivers that have not yet entered the Active-Rx State, as defined in B.5.6.7.1 and B.5.6.7.2, shall be set to all ONEs. + +The operational status is determined by the application. + +NOTE – Transceivers in a REG are at no time fully transparent in so far as some HOH-bits will be overwritten. + +### **B.5.6.1.4 Signal Quality (SQ)** + +The signal quality is estimated at the receivers of LTU, NTU and REG (if provided). This value is used to estimate the bit error ratio (BER) of the received data. It takes into account the signal to interference ratio (SIR), where interference includes noise and residual echo and distortion. + +SQ has the same significance as "noise margin" defined in 5.6.1.4. + +### **B.5.6.2 Control and status signals** + +See 5.6.2 for definitions of virtual control and status signals involved in the loop activation procedure. Departures from these definitions are as follows: + +- For LOSW refer to Figure B.20. +- For INDC and INDR, the term noise margin should be replaced by signal quality. + +### **B.5.6.3 Transmitted signals** + +The following is the description of the transmitted signals during loop activation. + +#### **B.5.6.3.1 Silent** + +No signal is transmitted to the line during this state. + +#### **B.5.6.3.2 S0 signal** + +The S0 signal is used by the LTU for transceiver alerting ("wake up") and a time stamp sequence. It is used by the NTU transceivers for indicating that the NTU transceiver has detected S0 and is ready to proceed with start up. S0 transmitted from the LTU is referred to as CS0 and as RS0 from the NTU. Both CS0 and RS0 are 3150 symbols in length. S0 is a 2-point, in-phase, pseudo-noise sequence. The sequence uses the generating polynomial $1 \oplus x^{-5} \oplus x^{-6}$ seeded with bits $[0, 1, 2, 3, 4, 5] = 000001$ ; i.e. the sequence is initiated with all stages of the pseudo random sequence generator set to ZERO except the most significant stage which is set to ONE. The sequence generator is driven with all ONEs. The sequence is transmitted at the corresponding symbol rate used in the data mode (233.60 kbaud for 1168 kbit/s transceivers and 386.667 kbaud for 2320 kbit/s transceivers). The bit-to-symbol mapping for the S0 is given in Table B.3. + +**Table B.3/G.991.1 – S0 bit-to-symbol in-phase mapping** + +| Bit | Symbol | +|-----|--------| +| 0 | –A | +| 1 | +A | + +NOTE – A is the amplitude corresponding to the required transmit power (see B.5.6.5.1 and B.5.8.4.1). + +#### **B.5.6.3.3 S1 signal** + +The S1 signal is an uncoded 64-CAP signal transmitted at full power. It uses the generating polynomial $1 \oplus x^{-5} \oplus x^{-23}$ in the direction from LTU to the NTU is referred to as CS1. It uses the generating polynomial $1 \oplus x^{-18} \oplus x^{-23}$ in the direction from the NTU to the LTU and is referred to as RS1. The generating polynomials are implemented using the self synchronizing scrambler mode illustrated in Figure B.6 with an all ONEs input. The uncoded CAP signal constellation is shown in Figure B.1. + +#### **B.5.6.3.4 S2 signal** + +The S2 signal is a coded 64-CAP signal transmitted at full power (see B.5.8.4.1). It uses the generating polynomial $1 \oplus x^{-5} \oplus x^{-23}$ in the direction from the LTU to the NTU is referred to as CS2. It uses the generating polynomial $1 \oplus x^{-18} \oplus x^{-23}$ in the direction from the NTU to the LTU and is referred to as RS2. The generating polynomials are implemented using the self synchronizing scramblers mode illustrated in Figure B.5 with an all ONEs input. The coded CAP signal constellations are shown in Figure B.3. + +#### **B.5.6.3.5 S3 signal** + +The S3 signal is a coded 64-CAP signal that includes framing and is transmitted at full power. It uses the generating polynomial $1 \oplus x^{-5} \oplus x^{-23}$ in the direction from the LTU to the NTU is referred to as CS3. It uses the generating polynomial $1 \oplus x^{-18} \oplus x^{-23}$ in the direction from the NTU to the LTU and is referred to as RS3. The generating polynomials are implemented using the locked scrambler mode illustrated in Figure B.6. + +#### **B.5.6.4 Timers** + +The following timers are involved in the loop activation procedure of the HDSL transceiver. The timer values are indicated in Table B.4. The timeline of the loop activation sequence is given in Figure B.9. + +**Table B.4/G.991.1 – Timer values for start-up** + +| System | Lower bound (T) | < | Timer number | < | Upper bound (T) | LTU/NTU | +|-----------|-----------------|---|--------------|---|----------------------------------------------|-------------| +| 1P and 2P | 2 250 | < | T1 | < | 3 200 | NTU and NTU | +| 2P | 8 000 | < | T2 | | | LTU | +| 1P and 2P | 4 000 | < | T3 | < | 6 000 | NTU | +| 1P and 2P | | | T4 | < | 500 | LTU | +| 1P and 2P | 1 000 | < | T5 | | | NTU | +| 1P and 2P | | | T6 | < | 500 | NTU | +| 1P and 2P | | | T7 | < | 1 000 | NTU | +| 1P | 35 000 | < | T8 | < | 36 000 | LTU | +| 2P | 27 000 | < | T8 | < | 28 000 | LTU | +| 1P and 2P | 575 000 | < | T9 | < | 585 000 | LTU | +| 1P and 2P | | | T10 | < | 1 000 | NTU | +| 1P and 2P | 240 000 | < | T11 | < | 250 000 | LTU | +| 1P and 2P | 240 000 | < | T12 | | 250 000 | NTU | +| 1P and 2P | | | T-Act | < | $2.5 \times 10^6$ (2P, 10.7 s and 1P, 6.5 s) | LTU and NTU | + +NOTE – For 1168 kbit/s transceivers (2P), T = 1 divided by (1168 kbit/s divided by 5 bit/symbol) = 4.281 µs/symbol and, for 2320 kbit/s transceivers (2P), T = 1 divided by (2320 kbit/s divided by 6 bit/symbol) = 2.5862 µs/symbol + +![Figure B.9/G.991.1 – CAP HDSL Transceiver activation sequences – Dual channel mode. The diagram shows the timing and state transitions for LTU-B, NTU-B, LTU-A, and NTU-A transceivers. It includes signal states like S0, CS1, RS1, CS2, RS2, CS3, and RS3. Timing parameters are given in units of T and kT, such as 1100 kT ± 1 kT, 2300 T ± 100 T, and 85 000 T ± 300 T. Key events include 'Start T-Act', 'Reset Scrambler', 'Lock descrambler (LD)', and 'T-Act Expires'.](7e12e1e0d03a03790d2e9d74c3454bff_img.jpg) + +The diagram illustrates the activation sequence for CAP HDSL transceivers in dual channel mode across four lines: LTU-B, NTU-B, LTU-A, and NTU-A. + +**Top Section:** + +- LTU-B:** Shows state S0 followed by a transition to a state described as "The same as LTU-A". +- NTU-B:** Shows state S0 followed by a transition to a state described as "The same as NTU-A". +- LTU-A:** Transitions through S0 states (marked with T1) to CS1. Timing includes $1100 \text{ kT} \pm 1 \text{ kT}$ , $290 \text{ T}$ , and $585\,000 \text{ T} \pm 100 \text{ T}$ . +- NTU-A:** Transitions through S0 to RS1. Timing includes $2300 \text{ T} \pm 100 \text{ T}$ (T6) and a "Reset Scrambler" event at $13 \pm 2 \text{ T}$ . + +**Bottom Section (Continuation):** + +- LTU-A:** Continues from CS1 to "4 CAP Tomlinson Exchange", then back to CS1, followed by CS2 and CS3. Timing includes $650 \pm 3 \text{ T}$ , $290 \text{ T}$ (T8), and $85\,000 \text{ T} \pm 300 \text{ T}$ (T11) for "Lock descrambler (LD)". +- NTU-A:** Continues from RS1, through a brief S0, back to RS1, then "4 CAP Tomlinson Exchange", RS2, and RS3. Timing includes $128\,000 \text{ T} \pm 500 \text{ T}$ , $13 \pm 2 \text{ T}$ (Reset Scrambler), $510 \pm 3 \text{ T}$ (T10), and $85\,000 \text{ T} \pm 300 \text{ T}$ (T12) for "LD". + +The sequence concludes with "T-Act Expires". Reference: T1529320-98. + +Figure B.9/G.991.1 – CAP HDSL Transceiver activation sequences – Dual channel mode. The diagram shows the timing and state transitions for LTU-B, NTU-B, LTU-A, and NTU-A transceivers. It includes signal states like S0, CS1, RS1, CS2, RS2, CS3, and RS3. Timing parameters are given in units of T and kT, such as 1100 kT ± 1 kT, 2300 T ± 100 T, and 85 000 T ± 300 T. Key events include 'Start T-Act', 'Reset Scrambler', 'Lock descrambler (LD)', and 'T-Act Expires'. + +**Figure B.9/G.991.1 – CAP HDSL Transceiver activation sequences – Dual channel mode** + +#### **B.5.6.4.1 T1** + +T1 is the duration of time that an LTU transceiver waits, after the transmission of CS0 for the receipt of RS0 from the corresponding transceiver in an NTU, before, for a two-pair transceiver, it initiates the transmission of CS0 to the NTU transceiver on the second channel and, for a one-pair transceiver, it retransmits CS0. + +#### **B.5.6.4.2 T2** + +T2 is the duration of time that a two-pair LTU waits, before it reverts to the single pair mode of operation, for an RS0 "I'm alerted" response from the transceiver in the NTU after it has sent the CS0 alerting signal to the transceiver, and when it has previously received an RS0 "I'm alerted" response from the other transceiver in the NTU (see Figure B.9). Note that it does not revert to the single pair mode of operation unless such mode of operation is enabled. + +#### **B.5.6.4.3 T3** + +T3 is the duration of time that a two-pair NTU waits, before it reverts to preparation for the single pair mode of operation, for a CS0 alerting signal to a transceiver after it has sent an RS0 "I'm alerted" signal from its other transceiver. Note that the single pair mode of operation is not established unless such mode of operation of the LTU is enabled. + +#### **B.5.6.4.4 T4** + +T4 is the maximum time that an LTU waits, after the receipt of RS0 from the NTU indicating that it has been alerted, before it initiates the transmission of CS1. [Note that in normal dual channel operation, the timer applies after both transceivers in the NTU have sent RS0 but, in single channel operation (fall-back mode), the timer applies after the transceiver on the channel of interest has sent RS0.] + +#### **B.5.6.4.5 T5** + +T5 is the time an NTU waits for the detection of CS1, as appropriate, after transmitting RS0, before it reverts to the initial alerting mode. For a two-pair system, T5 is started only after RS0 is transmitted in response to CS0 in the second channel to be alerted. + +#### **B.5.6.4.6 T6** + +T6 is the maximum time that a transceiver in an NTU requires to detect CS1 and initiate the transmission of RS1 when it first enters the alerted state. + +#### **B.5.6.4.7 T7** + +T7 is the maximum time that an NTU continues to send Silent after it detects the end of the CS1 ideal reference sequence. + +#### **B.5.6.4.8 T8** + +T8 is the time that an LTU transceiver sends Silent following the termination of its transmission of the ideal reference sequence and its detection of RS1 from the NTU transceiver before it initiates the transmission of CS1. The NTU transceiver trains its echo canceller during this interval. + +#### **B.5.6.4.9 T9** + +T9 is the duration of time that a transceiver in an LTU transmits CS1 after the time it detects the RS0 time stamp signal from the transceiver in the NTU before it initiates the Tomlinson coefficient exchange. + +#### **B.5.6.4.10 T10** + +T10 is the maximum time that an NTU transceiver can delay after receiving the Tomlinson coefficients from the LTU transceiver before it initiates transmission of Tomlinson coefficients to the LTU transceiver. + +#### **B.5.6.4.11 T11** + +T11 is the time that an LTU transceiver shall delay after receiving the Tomlinson coefficients from the NTU transceiver before it may lock its descrambler. + +#### **B.5.6.4.12 T12** + +T12 is the time that an NTU transceiver shall delay after completing the transmission of its Tomlinson coefficients before it may lock its descrambler. + +#### **B.5.6.4.13 T-Act** + +The activation timer for the HDSL transceivers (T-Act) is the length of time in which the loop activation procedure in the HDSL transceiver in the LTU or HDSL transceiver in the NTU should have successfully ended, starting from the point in time where the transceiver at the NTU starts to transmit the S1 signal. At the NTU, T-Act starts when transmission of RS1 is initiated and, in the LTU, T-Act starts when the RS1 is detected. + +#### **B.5.6.4.14 Timer values** + +The timer values (in symbol intervals, T) are listed in Table B.4. + +### **B.5.6.5 HDSL transceiver activation** + +The CAP HDSL transceiver start-up procedure is described in this subclause. The complete start-up sequence (for the dual channel mode) is shown in Figure B.9. + +#### **B.5.6.5.1 Alerting** + +##### **B.5.6.5.1.1 Two-pair system alerting sequence** + +###### **B.5.6.5.1.1.1 Alerting in normal dual channel mode** + +The alerting ("wake up") sequence for both channels A and B is shown in Figure B.10. + +Alerting is initiated by the HDSL transceiver in the LTU transmitting the CS0 sequence on channel A to alert the corresponding transceiver in the NTU. The HDSL transceiver in the LTU then transmits Silent and monitors for a reply from the NTU. Upon detection of the CS0 sequence, the HDSL transceiver in the NTU replies by transmitting the sequence (RS0). Following the receipt of RS0 in channel A, the LTU transmits CS0 in channel B. The receipt of the sequence RS0 from the NTU transceiver on channel B indicates that the NTU has been alerted and start-up procedure continues. Upon the transmission of CS0 in channel B, the NTU starts timer T5 and waits for the receipt of CS1 from the LTU in both channels. + +As shown in Figure B.10, if no NTU reply is received in response to the transmission of an CS0 sequence for a period of T1 symbols, the LTU transceiver repeats the transmission of the CS0 sequence on the other channel in an attempt to alert the associated NTU transceiver. The LTU transceiver alternately transmits the CS0 sequence and Silent, alternatively polling first on channel A and then on channel B, until replies are received from both transceivers in the NTU. + +If a reply is received from one of the transceivers in the NTU, the LTU continues to alternately transmit the CS0 sequence and Silent to the transceiver on the other channel until it replies or T-Act expires. The LTU proceeds as described in B.5.6.7.2. The single-channel mode may then be enabled. + +for the channel that replied and alerting would proceed as described in B.5.6.5.1.1.2. Note that, as explained in B.5.6.7, alerting by the LTU is initiated only if ACTREQ is equal to ONE. + +When the NTU completes the transmission of the RS0 "I'm alerted" sequence from the first transceiver alerted, it starts timer T3. If the alerting S0 sequence is received from the LTU by the second NTU transceiver before the timer expires, the NTU continues the alerting process for the dual channel mode. The alternative is described in B.5.6.5.1.1.2. + +![Figure B.10/G.991.1 – Alerting sequence for both channels of two-pair HDSL transceiver. This sequence diagram shows the interaction between LTU-B, NTU-B, LTU-A, and NTU-A. LTU-A sends CS0, NTU-A responds with RS0, LTU-B sends CS0, and NTU-B responds with RS0. Timers T1, T2, T3, and T5 are shown. Low power CD detect for channel A and B are also indicated.](2d548db0b26b7bf33244320322d5ee2c_img.jpg) + +The diagram illustrates the alerting sequence for both channels of a two-pair HDSL transceiver. The sequence of events is as follows: + +- LTU-B and LTU-A transmit CS0 sequences. +- NTU-A receives CS0 and responds with an RS0 sequence. +- LTU-B transmits a CS0 sequence after a delay. +- NTU-B receives CS0 and responds with an RS0 sequence. +- Timers T1 and T2 are associated with the CS0/RS0 exchange on channel A. +- Timer T3 is started by NTU-A upon completion of its RS0 transmission. +- Timer T5 is started by NTU-B upon completion of its RS0 transmission. +- Low power CD detect for channel A and B are indicated at the bottom. + +Figure B.10/G.991.1 – Alerting sequence for both channels of two-pair HDSL transceiver. This sequence diagram shows the interaction between LTU-B, NTU-B, LTU-A, and NTU-A. LTU-A sends CS0, NTU-A responds with RS0, LTU-B sends CS0, and NTU-B responds with RS0. Timers T1, T2, T3, and T5 are shown. Low power CD detect for channel A and B are also indicated. + +**Figure B.10/G.991.1 – Alerting sequence for both channels of +two-pair HDSL transceiver** + +After receiving an RS0 response, the LTU shall send the corresponding CS0 poll on the other channel as described above. + +The LTU continuously polls the NTU transceivers until an RS0 reply is received on both channels or T-Act expires. + +The power of the S0 sequences from both the LTU and NTU shall be $-1.5 \text{ dBm} \pm 1 \text{ dB}$ or nominally 15 dB below the high transmit power specified in B.5.8.4.1. + +**B.5.6.5.1.1.2 Alerting in single-channel mode** + +In the single-channel mode of a two-pair system, the LTU transceiver on the channel to be activated transmits alternately the CS0 sequence and Silent until it receives a reply from the corresponding NTU transceiver. The sequence is shown in Figure B.11. + +![Figure B.11/G.991.1 – Alerting sequence for single-channel mode. This sequence diagram shows the interaction between LTU-A/B and NTU-A/B. LTU-A/B sends CS0, NTU-A/B responds with RS0, LTU-A/B sends CS0, and NTU-A/B responds with RS0. Timers T1, T2, T3, T4, and T5 are shown.](56468323fb2f5ff6f0a8bf9bf1f691e8_img.jpg) + +The diagram illustrates the alerting sequence for single-channel mode. The sequence of events is as follows: + +- LTU-A/B transmits a CS0 sequence. +- NTU-A/B receives CS0 and responds with an RS0 sequence. +- LTU-A/B transmits another CS0 sequence after a silent period. +- NTU-A/B receives the second CS0 and responds with another RS0 sequence. +- Timers T1 and T2 are associated with the CS0/RS0 exchange. +- Timer T3 is started by NTU-A/B upon completion of its first RS0 transmission. +- Timer T4 is associated with the LTU's second CS0 transmission. +- Timer T5 is started by NTU-A/B upon completion of its second RS0 transmission. + +Figure B.11/G.991.1 – Alerting sequence for single-channel mode. This sequence diagram shows the interaction between LTU-A/B and NTU-A/B. LTU-A/B sends CS0, NTU-A/B responds with RS0, LTU-A/B sends CS0, and NTU-A/B responds with RS0. Timers T1, T2, T3, T4, and T5 are shown. + +**Figure B.11/G.991.1 – Alerting sequence for single-channel mode** + +After the NTU finishes the transmission of the RS0 "I'm alerted" reply, it starts a timer, T3. If no CS0 alerting signal is received by the second transceiver of the NTU before this timer expires, the + +NTU reverts to activating in the single-channel mode and transmits RS0 a second time. In this way, the NTU automatically adopts the single-channel mode when such a mode is enabled at the LTU. Note that activation is completed only if the LTU continues the process by transmitting CS1. + +When the LTU receives an RS0 "I'm alerted" reply from the transceiver of the NTU, the LTU starts a timer T2. If the second RS0 is received prior to the time-out of T2 and the LTU wishes to activate the channel in the single-channel mode, it continues the activation process as indicated in Figure B.11. It delays the initiation of CS1 on the channel until T4 unit intervals after the second RS0 are received. If the second RS0 is not received before timer T2 times out, it may initiate a second attempt to activate the channel by transmitting CS0. + +The LTU will activate either channel A or B if the single-channel mode of operation is enabled. + +#### B.5.6.5.1.2 One-pair transceiver alerting sequence + +The alerting sequence for single pair transceivers is essentially the same as for transceivers of two-pair systems in the single-channel mode. The sequence is shown in Figure B.12. The LTU transceiver transmits alternately the CS0 sequence and Silent until it receives a reply from the corresponding NTU transceiver. + +After the NTU finishes the transmission of the RS0 "I'm alerted" reply, it starts a timer, T5 and waits for CS1 from the LTU. Upon receiving RS0 from the NTU, the LTU transmits CS1. + +![Timing diagram for alerting sequence. The top line represents LTU-A/B, showing two CS0 blocks separated by a dashed line. A timer T1 is indicated between the start of the first CS0 and the start of the second CS0. The bottom line represents NTU-A/B, showing an RS0 block. Vertical lines connect the end of the second CS0 on the LTU line to the start of the RS0 block on the NTU line, and from the end of the RS0 block to the start of the CS1 block on the LTU line. A timer T4 is indicated between the start of the RS0 block and the start of the CS1 block. A timer T5 is indicated starting at the end of the RS0 block on the NTU line. The diagram is labeled 'Start T5' and 'T1529350-98'.](ff06304def736f4144f7bdd2957b9e22_img.jpg) + +Timing diagram for alerting sequence. The top line represents LTU-A/B, showing two CS0 blocks separated by a dashed line. A timer T1 is indicated between the start of the first CS0 and the start of the second CS0. The bottom line represents NTU-A/B, showing an RS0 block. Vertical lines connect the end of the second CS0 on the LTU line to the start of the RS0 block on the NTU line, and from the end of the RS0 block to the start of the CS1 block on the LTU line. A timer T4 is indicated between the start of the RS0 block and the start of the CS1 block. A timer T5 is indicated starting at the end of the RS0 block on the NTU line. The diagram is labeled 'Start T5' and 'T1529350-98'. + +Figure B.12/G.991.1 – Alerting sequence for one-pair transceiver + +#### B.5.6.5.2 Transmit power mode selection + +During alerting, the LTU and NTU transceivers measure the received level of the S0 sequences and choose either the high transmit power (HP) or the low transmit power (LP) mode, which are specified in Table B.5 (see also B.5.8.4.1). (Note that the use of the lower transmit power on short lines reduces the required linear range of the receiver.) The chosen transmit power modes are maintained during and after activation and are "full power" for the installation. As described in B.5.6.5.6, receivers are informed of the transmit power modes of far end transmitters during the Tomlinson coefficient exchange. + +Table B.5/G.991.1 – Transmit power mode selection criteria + +| Power mode | Line loss for S0 in dB | +|------------|------------------------| +| HP | > 9 | +| HP or LP | 6 to 9 | +| LP | < 6 | + +### B.5.6.5.3 Front-end training + +Front-end training is initiated after the successful completion of the alerting process. The primary purpose of the front-end training phase is to align any automatic gain control function at the receiver that is ahead of the A/D conversion function. This portion of the start-up sequence is shown in Figure B.13. + +![Timing diagram for Figure B.13/G.991.1 – Start-up sequence – analogue front end training. The diagram shows signal activity on four lines: LTU-B, NTU-B, LTU-A, and NTU-A. LTU-B and NTU-B are shown as 'The same as LTU-A' and 'The same as NTU-A' respectively. LTU-A transmits CS1, S0, and CS1. NTU-A transmits RS1. Timing intervals T4, T6, and T7 are marked. T4 is 1100 kT ± 1 kT. T6 is 3300 T ± 100 T. A 'Wake-up completed' signal is shown at the bottom left.](2c41e286ea9a1b008d3beb348d86096f_img.jpg) + +The diagram illustrates the start-up sequence for analogue front-end training. It features four horizontal lines representing signal paths: LTU-B, NTU-B, LTU-A, and NTU-A. LTU-B and NTU-B are indicated as being the same as LTU-A and NTU-A respectively. LTU-A transmits a sequence of CS1, S0, and CS1. NTU-A transmits RS1. Timing intervals are marked: T4 (1100 kT ± 1 kT) for the CS1 transmission on LTU-A, and T6 (3300 T ± 100 T) for the RS1 transmission on NTU-A. A 'Wake-up completed' signal is shown at the bottom left, indicating the start of the sequence. + +Timing diagram for Figure B.13/G.991.1 – Start-up sequence – analogue front end training. The diagram shows signal activity on four lines: LTU-B, NTU-B, LTU-A, and NTU-A. LTU-B and NTU-B are shown as 'The same as LTU-A' and 'The same as NTU-A' respectively. LTU-A transmits CS1, S0, and CS1. NTU-A transmits RS1. Timing intervals T4, T6, and T7 are marked. T4 is 1100 kT ± 1 kT. T6 is 3300 T ± 100 T. A 'Wake-up completed' signal is shown at the bottom left. + +Figure B.13/G.991.1 – Start-up sequence – analogue front end training + +The LTU transceivers start transmitting CS1 within T4 symbols after the NTU RS0 alert indication is completed. Transmission continues for a period of $1100 kT \pm 1 kT$ . Upon receiving this signal, the NTU transceivers initiate transmission of RS1 for a period of $3300 T \pm 100 T$ . The NTU must detect and initiate the transmission of RS1 within an interval of T6 symbols. During the period when a transceiver is transmitting and receiving signals, its front end AGC is trained. + +### B.5.6.5.4 Timing recovery, echo canceller and equalizer training + +This portion of the start-up sequence is shown in Figure B.14. After an NTU transceiver stops transmitting RS1, it initiates timing recovery from the CS1 signal received from the LTU transceiver and the LTU transceiver initiates training of its echo canceller. + +![Timing diagram for Figure B.14/G.991.1 – NTU ideal reference training sequence. The diagram shows signal activity on two lines: LTU and NTU. LTU transmits CS1, S0, and CS1. NTU transmits RS1. Timing intervals are marked: 290 T, 585 000 T ± 100 T, and 13 ± 2 T. A 'Reset scrambler' signal is shown on the NTU line. A T7 symbol interval is also marked.](74e409e1548dd2606c4de9bdfe9806e4_img.jpg) + +The diagram illustrates the NTU ideal reference training sequence. It features two horizontal lines representing signal paths: LTU and NTU. LTU transmits a sequence of CS1, S0, and CS1. NTU transmits RS1. Timing intervals are marked: 290 T for the S0 symbol on LTU, 585 000 T ± 100 T for the CS1 symbol on LTU, and 13 ± 2 T for the RS1 symbol on NTU. A 'Reset scrambler' signal is shown on the NTU line. A T7 symbol interval is also marked. + +Timing diagram for Figure B.14/G.991.1 – NTU ideal reference training sequence. The diagram shows signal activity on two lines: LTU and NTU. LTU transmits CS1, S0, and CS1. NTU transmits RS1. Timing intervals are marked: 290 T, 585 000 T ± 100 T, and 13 ± 2 T. A 'Reset scrambler' signal is shown on the NTU line. A T7 symbol interval is also marked. + +Figure B.14/G.991.1 – NTU ideal reference training sequence + +Following the transmission of CS1, each LTU transceiver transmit CS0 (at full power) as a time stamp signal for a duration of 290 symbols to signal the start of the ideal reference sequence. This alerts the associated NTU transceivers that an ideal reference sequence is about to be transmitted. The ideal reference is initiated by resetting the scrambler $13 \pm 1$ symbols after CS0 is completed. (Note that the initiation of CS1 may be delayed until the ideal reference signal is initiated or it may be initiated immediately after the completion of CS0 as shown in the figures.) The ideal reference sequence is CS1 synchronized with the symbol clock in a defined way; thereby providing a defined pseudo random sequence of symbols. The ideal reference CS1 sequence is initiated with the generator seeded with bits [0, 1, 2, 3, -, 23] = 0000-0; i.e. the sequence is initiated with all stages of the pseudo random sequence generator set to ZERO. The generator is driven with all ONEs. The sequence starts with a symbol and the time stamp sequence identifies this starting point at the receiver. The sequence is continued for a period of $585\,000 \pm 100$ symbols. + +Upon receiving the ideal reference sequence, the NTU transceivers initiate training of its equalizer. Note that the receiver knows the sequence transmitted and the synchronization of the sequence with its symbol clock and therefore it knows the point in the 64-CAP constellation of each received symbol. + +After the LTU transceiver completes transmission of CS1, the NTU transceiver transmits RS1 (but not as an ideal reference) for a period of $128\,000 \pm 500$ symbols. The LTU transceiver is silent for a period T8 symbol intervals. During this period, while the NTU transceiver is transmitting in the absence of a received signal, the NTU trains its echo canceller. This portion of the start-up sequence is shown in Figure B.15. As shown in Figure B.15, the LTU transceiver initiates transmission of CS1 after T8 silent interval. + +![Timing diagram for LTU ideal reference sequence training. The diagram shows two horizontal timelines for LTU and NTU. The NTU timeline starts with a block labeled 'RS1' of duration '128 000 ± 500 T', followed by a block labeled 'S0' of duration '290 T', and then another 'RS1' block. Below the 'S0' block, a 'Reset scrambler' event is marked at a distance of '13 ± 2 T' from the start of the 'S0' block. The LTU timeline shows a silent period 'T8' (indicated by a double-headed arrow with 'X' marks) starting from the beginning of the NTU's 'RS1' block. After 'T8', the LTU begins transmission of 'CS1', which continues as a dashed line. A vertical dashed line aligns the start of the LTU's 'CS1' transmission with the start of the NTU's 'S0' block. The diagram is labeled 'T1529380-98' at the bottom right.](9b39a1d27e49bccd8767e8d5fc0be7fd_img.jpg) + +Timing diagram for LTU ideal reference sequence training. The diagram shows two horizontal timelines for LTU and NTU. The NTU timeline starts with a block labeled 'RS1' of duration '128 000 ± 500 T', followed by a block labeled 'S0' of duration '290 T', and then another 'RS1' block. Below the 'S0' block, a 'Reset scrambler' event is marked at a distance of '13 ± 2 T' from the start of the 'S0' block. The LTU timeline shows a silent period 'T8' (indicated by a double-headed arrow with 'X' marks) starting from the beginning of the NTU's 'RS1' block. After 'T8', the LTU begins transmission of 'CS1', which continues as a dashed line. A vertical dashed line aligns the start of the LTU's 'CS1' transmission with the start of the NTU's 'S0' block. The diagram is labeled 'T1529380-98' at the bottom right. + +**Figure B.15/G.991.1 – LTU ideal reference sequence training** + +Once the NTU transceiver has completed transmission of RS1, the NTU transceiver transmits S0, for a period of 290 symbols at full power, as a time stamp signal. This signals the beginning of the transmission of the ideal reference sequence by the NTU transceiver having all of the characteristics described above. (Note that, as described above for the LTU, the initiation of the CS1 sequence may immediately follow the transmission of CS0 for 290 symbols, as shown in the figures, or it may be delayed until the scrambler is reset). While it is receiving the ideal reference sequence, the LTU transceiver trains its equalizer. + +Note that the NTU transceiver must maintain timing such that it is in synchronization after the interval during which the LTU transceiver is silent. + +### B.5.6.5.5 Tomlinson coefficient exchange + +After the LTU transceiver has received RS1 for an interval T9, the LTU transceiver transmits the decision feedback equalizer coefficients for the Tomlinson precoder for a period of 650 symbols as indicated in Figure B.16. Once the LTU transceiver has completed transmission of the Tomlinson coefficients, it continues the transmission of CS1. After the NTU transceiver completes the reception of the Tomlinson coefficients, it transmits its coefficients for a period of 510 symbols. The NTU transceiver may delay transmission of its coefficients by up to T10 symbols. The Tomlinson coefficients are the coefficients of the feedback filter in the Tomlinson precoder [B2]. + +![Figure B.16/G.991.1 – Start-up sequence – Tomlinson coefficients exchange. This timing diagram illustrates the interaction between LTU and NTU. LTU transmits CS1, then a '4 CAP Tomlinson Exchange' for 650 ± 3 T, then resumes CS1, followed by CS2 and CS3. NTU transmits RS1, then after a delay T10, its own '4 CAP Tomlinson Exchange' for 510 ± 3 T, followed by RS2 and RS3. Timing markers T11 and T12 are shown, along with a 'Lock descrambler (LD)' period of 85 000 ± 100 T on the LTU side. Diagram reference T1529390-98.](c05763eff20551449de1eac378fed769_img.jpg) + +Figure B.16/G.991.1 – Start-up sequence – Tomlinson coefficients exchange. This timing diagram illustrates the interaction between LTU and NTU. LTU transmits CS1, then a '4 CAP Tomlinson Exchange' for 650 ± 3 T, then resumes CS1, followed by CS2 and CS3. NTU transmits RS1, then after a delay T10, its own '4 CAP Tomlinson Exchange' for 510 ± 3 T, followed by RS2 and RS3. Timing markers T11 and T12 are shown, along with a 'Lock descrambler (LD)' period of 85 000 ± 100 T on the LTU side. Diagram reference T1529390-98. + +**Figure B.16/G.991.1 – Start-up sequence – Tomlinson coefficients exchange** + +The data transfer is done by switching to the 4 CAP signal structure shown in Figure B.17. This provides reliable transmission without coding, which is enabled after the transfer is completed. + +![Figure B.17/G.991.1 – 4 CAP signal structure – Tomlinson coefficient exchange. A constellation diagram on a grid from -7 to 7 on both axes. Four points are circled and labeled: A (7, 7) = 00, B (-7, -7) = 11, C (7, -7) = 01, and D (-7, 7) = 10. Diagram reference T1529400-98.](23aceb0e7d3c1a644294899d9047df05_img.jpg) + +Figure B.17/G.991.1 – 4 CAP signal structure – Tomlinson coefficient exchange. A constellation diagram on a grid from -7 to 7 on both axes. Four points are circled and labeled: A (7, 7) = 00, B (-7, -7) = 11, C (7, -7) = 01, and D (-7, 7) = 10. Diagram reference T1529400-98. + +**Figure B.17/G.991.1 – 4 CAP signal structure – Tomlinson coefficient exchange** + +The data frame structure used to transmit the coefficients is shown in Figure B.18. The data frame starts with 128 symbol (4 point) long repetition of ABAB (see Figure B.17) for synchronization or identification of the start of coefficient data frame. This is followed with a data block marker which + +is CD (shown in Figure B.18) for an HDSL one-pair system and channel A of a two-pair system and which is DC for channel B of a two-pair system. As described in B.5.6.7, these data block markers also provide for pair identification. + +![Figure B.18/G.991.1 – Tomlinson coefficient frame structure. The diagram shows a '4 point CAP Tomlinson exchange frame' containing 'DP-C/R-A/B', 'ABAB', 'CD', 'data LSB-MSB', and '16 bits checksum'. A '128 T' marker is shown within the frame. Below this, a 'Data block' is shown with fields: '8 bits size', '64 bits control', '16 bits 10/A', '16 bits 11/A', '16 bits 18/A', '16 bits Q0/A', '16 bits Q1/A', '16 bits Q8/A', '16 bits 10/B', '16 bits II1/B', '16 bits 18/B', '16 bits Q0/B', '16 bits Q1/B', and '16 bits Q8/B'. The diagram is labeled T1529410-98.](d665f520401064e5cfeed94d226f48bd_img.jpg) + +Figure B.18/G.991.1 – Tomlinson coefficient frame structure. The diagram shows a '4 point CAP Tomlinson exchange frame' containing 'DP-C/R-A/B', 'ABAB', 'CD', 'data LSB-MSB', and '16 bits checksum'. A '128 T' marker is shown within the frame. Below this, a 'Data block' is shown with fields: '8 bits size', '64 bits control', '16 bits 10/A', '16 bits 11/A', '16 bits 18/A', '16 bits Q0/A', '16 bits Q1/A', '16 bits Q8/A', '16 bits 10/B', '16 bits II1/B', '16 bits 18/B', '16 bits Q0/B', '16 bits Q1/B', and '16 bits Q8/B'. The diagram is labeled T1529410-98. + +**Figure B.18/G.991.1 – Tomlinson coefficient frame structure** + +The unscrambled data block words are transmitted in 4 point symbols as shown in Figure B.17 and Table B.6. For two-pair transceivers, there are 9 inphase and 9 quadrature coefficients. Note that the coefficients for both channels A and B are sent in data frames on both channels. For one-pair transceivers, there are 12 inphase and 12 quadrature coefficients. The last 16 bits of a data frame is a checksum equal to the 2's complement of the data block sum. + +**Table B.6/G.991.1 – Tomlinson coefficient data block words** + +| Data block words | | Notes | +|--------------------------------------------------------------------------|---------------|---------------------------| +| Type | Size – bits | | +| Block size | 8 | Frame size bits | +| Control field | 64 | See B.5.6.5.6 | +| I[0-N-1]/A | $16 \times N$ | N in-phase coefficients | +| Q[0-N-1]/A | $16 \times N$ | N quadrature coefficients | +| I[0-(N-1)]/B | $16 \times N$ | N in-phase coefficients | +| Q[0-(N-1)]/B | $16 \times N$ | N quadrature coefficients | +| NOTE – N is 9 for two-pair transceivers and 12 for one-pair transceiver. | | | + +Data frames for the A and B channels are transmitted simultaneously. + +As shown in Figure B.18, the first 8 bits of a data block defines the size of the data block. The 64-bit control block bit assignments are specified in B.5.6.5.6. + +The reserved bits of the data block are followed by 16-bit words, defining the inphase coefficients and the quadrature coefficients, nine words for two-pair transceivers and 12 words for one-pair transceivers. As indicated in Figure B.18, the LSB of each coefficient is transmitted first. + +After the Tomlinson coefficients have been transmitted, both the LTU and NTU transceivers again transmit the uncoded 64-CAP sequence. The NTU transceivers transmit this sequence for T10 symbols. + +Following this transmission, the LTU and NTU transceivers initiate transmission of S3, a sequence that includes framing and is trellis coded. + +#### **B.5.6.5.6 Control field bit assignments** + +The assignment of bits in the 64-bit control field in the data block of the Tomlinson exchange frame (see Figure B.18) are specified in this subclause. The field is broken into four 16 bit words. The two least significant bits of the third 16-bit word is used to send the transmit power identifiers of the transceivers. For a two-pair system, the first bit is for channel A and the second bit is for channel B. For a one-pair system, the first bit is the transmit power identifier and the second bit is reserved. A ZERO indicates the low transmit power mode. A ONE indicates the high transmit power mode. Note that the transmit power mode is determined, as discussed in B.5.6.5.2, during alerting. The third and fourth bits of the third 16-bit word are reserved for future standardization and the fifth bit is used to identify a regenerator. A ONE indicates the transceiver is in a regenerator while a ZERO indicates that it is not in a regenerator. + +The remaining 11 bits of the third 16-bit word are reserved for future standardization. Reserved bits shall be set to ZERO. + +The first and the second 16-bit word are reserved for future requirements, the fourth 16-bit word is reserved for vendor-specific applications. + +#### **B.5.6.5.7 Transition to data mode** + +After the Tomlinson coefficients have been transmitted, the NTU transceiver shall transmit the coded 64-CAP sequence RS2. After the LTU transceiver completes the reception of the coefficients, it shall initiate the transmission of the framed sequence CS2 and lock its descrambler. However, it shall wait for an interval T11 before initiating the transmission of CS2, which it shall continue for a period of nominally 3000 symbols. During this nominally 3000 symbol period it shall lock its descrambler. Following this period, the LTU shall initiate the transmission of CS3, a sequence that includes framing and is trellis coded. The required sequence is shown in Figure B.16 + +Following the transmission of its Tomlinson coefficients, the NTU transceiver shall initiate the transmission of RS2. It shall continue the transmission of RS2 for an interval of T12 plus nominally 3000 symbols. It locks its descrambler during the nominally 3000 symbol interval. Following this interval, it shall initiate the transmission of RS3. + +Both the LTU and NTU transceivers shall lock their scramblers prior to initiating the transmission of S3 but after the Tomlinson coefficient exchange. (Note that scramblers must be locked during the time when the scramblers are being driven with continuous ONEs.) + +With both transceivers transmitting S3, the transceivers are in the data mode. + +#### **B.5.6.6 Retrain procedure** + +Retrain can be initiated by either the LTU transceiver or the NTU transceiver. To initiate retrain an NTU sends Silent. The LTU transceiver, upon detecting the absence of received signal for period of 1 s, initiates the transmission of S0 and retrain proceeds as above with the alerting sequence. LTU transceiver initiates retrain by sending Silent for 1 s followed by the transmission of the alerting sequence using S0 as shown in Figure B.10. Upon recognition of the sequence by the NTU transceiver, retrain proceeds as for initial training. Criteria (conditions – SQ, performance or synchronization) for the initiation of retrain are not specified. + +Note that retrain will be initiated, assuming ACTREQ = ONE, when either the NTU or the LTU goes to the "Inactive State" as implied by the state diagrams discussed in B.5.6.7. + +### B.5.6.7 Loop activation state diagrams + +The following subclauses describe the LTU and NTU state diagrams, as illustrated in Figures B.19 and B.20. + +![State diagram for HDSL transceiver at the NTU loop activation. The diagram shows six states: Inactive State, Deactivated State, Pending Deactivation State, Active-Rx State, Active-Tx/Rx State, and Active-Tx State. Transitions are triggered by events like Power on, LOS, T-Act expired, LOSW, and INDC.](72d448a65347c51989171748789c7d4b_img.jpg) + +``` + +stateDiagram-v2 + [*] --> InactiveState : Power on (ACTREQ = 1) + InactiveState --> DeactivatedState : LOS = 1 + InactiveState --> ActivatingState : LOS = 0 + DeactivatedState --> PendingDeactivationState : LOSWT = 1 + DeactivatedState --> ActivatingState : T-Act expired + PendingDeactivationState --> ActiveTxRxState : LOSW = 0 + PendingDeactivationState --> DeactivatedState : LOSW = 1 + ActiveRxState --> DeactivatedState : LOS = 1 + ActiveRxState --> PendingDeactivationState : LOSW = 1 + ActiveRxState --> ActiveTxRxState : INDC = 1 or T-Act expired + ActiveRxState --> ActivatingState : INDR = 1 + ActiveTxRxState --> PendingDeactivationState : LOSW = 1 + ActiveTxRxState --> ActiveRxState : INDC = 1 or T-Act expired + ActiveTxRxState --> DeactivatedState : LOS = 1 + ActiveTxRxState --> ActiveTxState : INDR = 1 or T-Act expired + ActiveTxState --> PendingDeactivationState : LOSW = 1 + ActiveTxState --> DeactivatedState : LOS = 1 + ActiveTxState --> ActiveTxRxState : INDC = 1 + ActiveTxState --> ActivatingState : INDC = 1 + + state "Inactive State" as InactiveState + InactiveState : Tx: Silent + state "Deactivated State" as DeactivatedState + DeactivatedState : Tx: Silent + state "Pending Deactivation State" as PendingDeactivationState + PendingDeactivationState : Tx: data + state "Active-Rx State" as ActiveRxState + ActiveRxState : Tx: S3, Rx: ready + state "Active-Tx/Rx State" as ActiveTxRxState + ActiveTxRxState : Tx: S3, data, Rx: data + state "Active-Tx State" as ActiveTxState + ActiveTxState : Tx: S3, Rx: not ready + state "Activating State" as ActivatingState + ActivatingState : Tx: Silent, S0, S1, S2 or S3 + +``` + +T1529420-98 + +State diagram for HDSL transceiver at the NTU loop activation. The diagram shows six states: Inactive State, Deactivated State, Pending Deactivation State, Active-Rx State, Active-Tx/Rx State, and Active-Tx State. Transitions are triggered by events like Power on, LOS, T-Act expired, LOSW, and INDC. + +Figure B.19/G.991.1 – HDSL transceiver at the NTU loop activation state diagram + +![Figure B.20/G.991.1 – HDSL transceiver at the LTU loop activation state diagram. The diagram shows five states: Inactive State (Tx: Silent), Deactivated State (Tx: Silent), Pending Deactivation State (Tx: data), Active-Rx State (Tx: S3, Rx: ready), and Active-Tx State (Tx: S3, Rx: not ready). Transitions are triggered by events like Power on (ACTREQ), LOST = 1, T-Act expired, LOSWT = 1, LOSW = 0, LOSW = 1, INDC = 1, and INDR = 1.](3d46409f8d0190e611a910ff27f8ec07_img.jpg) + +``` + +stateDiagram-v2 + [*] --> Inactive: Power on (ACTREQ) + Inactive --> Activating: ACTREQ = 1 + Activating --> Inactive: T-Act expired + Activating --> Deactivated: LOST = 1 + Activating --> Active-Rx: INDC = 1 + Activating --> Active-Tx: INDR = 1 + Active-Rx --> Pending Deactivation: LOSW = 1 + Active-Rx --> Active-Tx: INDR = 1 or T-Act expired + Pending Deactivation --> Deactivated: LOSWT = 1 + Pending Deactivation --> Active-Tx: LOSW = 0 + Active-Tx --> Pending Deactivation: LOSW = 1 + Active-Tx --> Active-Rx: INDC = 1 or T-Act expired + +``` + +Figure B.20/G.991.1 – HDSL transceiver at the LTU loop activation state diagram. The diagram shows five states: Inactive State (Tx: Silent), Deactivated State (Tx: Silent), Pending Deactivation State (Tx: data), Active-Rx State (Tx: S3, Rx: ready), and Active-Tx State (Tx: S3, Rx: not ready). Transitions are triggered by events like Power on (ACTREQ), LOST = 1, T-Act expired, LOSWT = 1, LOSW = 0, LOSW = 1, INDC = 1, and INDR = 1. + +**Figure B.20/G.991.1 – HDSL transceiver at the LTU loop activation state diagram** + +#### B.5.6.7.1 HDSL transceiver states at the NTU + +The command QUIET at any state (except the Inactive State) will cause a transition to the Deactivated State. The command QUIET, at the Inactive State, will not cause any transition. When the system is powered on, it enters the Inactive State after it completes all the self tests. + +Some of the transitions in the state diagrams depend on the detection of the INDC = ONE status arriving in the incoming data. The LTU transceiver will determine that INDC = ONE only if it detects this condition in six consecutive HDSL frames. + +##### B.5.6.7.1.1 Inactive State + +During the Inactive State the transmitters in NTU transceivers are silent, LOSW = ONE and LOS = ONE. The NTU transceivers wait for the detection of signal (S0) from the LTU transceiver. Upon detection of this signal the NTU changes to the Activating State (LOS = ZERO). + +##### B.5.6.7.1.2 Activating State + +During the Activating State the transmitted signal can be either S0, S1, S2, S3, or Silent. When the transceiver at the NTU enters this state from the Inactive State, it starts the T-Act timer and starts to transmit the RS0 signal from the transceiver on the channel on which it received CS0. LTU/NTU activation proceeds as described in B.5.6.5. When the NTU transmits the RS3 signal and the sync word (CS3) is detected, LOSW = ZERO. If INDR = ONE, the transceiver at the NTU changes to the Active-Rx State. If the NTU senses from CS3 arriving from the transceiver at the LTU with INDC = ONE, the transceiver at the NTU changes to the Active-Tx State. If the T-Act timer expires before CS3 is detected, the transceiver at the NTU goes to the Deactivated State. + +#### **B.5.6.7.1.3 Active-Rx State** + +During the Active-Rx State INDC = ZERO, INDR = ONE and the transceiver at the NTU is transmitting the S3 signal. At the same time the NTU is ready to receive data from the LTU. If the NTU senses from S3 arriving from the LTU that INDC = ONE, or if the T-Act timer expires, the NTU changes to the Active-Tx/Rx State. If frame sync has not been established, the NTU continues to monitor for the frame sync according to Figure B.19. + +#### **B.5.6.7.1.4 Active-Tx State** + +During the Active-Tx State INDC = ONE, INDR = ZERO and the NTU is transmitting RS3. At the same time the transceiver at the NTU is receiving the CS3. When frame sync is established, INDR = ONE, or when the T-Act timer expires, the NTU changes to the Active-Tx/Rx State. The NTU continues to monitor the frame sync, if it is not established, according to Figure B.19. + +#### **B.5.6.7.1.5 Active-Tx/Rx State** + +Upon entering the Active-Tx/Rx State the T-Act timer is deactivated. The transmitted signal is S3 or data. + +If HDSL frame synchronization is lost (LOSW = ONE), the NTU changes to the Pending Deactivation state. + +#### **B.5.6.7.1.6 Pending Deactivation State** + +During the Pending Deactivation State LOSW = ONE, and the transmitted signal is S3 (data). When the NTU enters this state a 2 s timer is started. If the HDSL frame synchronization is regained then LOSW = ZERO and the NTU returns to the Active-Tx/Rx State. If the 2 s timer expires, then LOSWT = ONE and the NTU changes to the Deactivated State. + +#### **B.5.6.7.1.7 Deactivated State** + +During the Deactivated State, no energy is transmitted to the line (i.e. Silent) and LOSW = ZERO. When the NTU enters this state it looks for signal power from the LTU. When no power is detected (LOS = ONE) the NTU changes to the Inactive State. + +### **B.5.6.7.2 HDSL transceiver states at LTU** + +The command QUIET at any state (except the Inactive State) will cause a transition to the Deactivated State. The command QUIET at the Inactive State will not cause any transition. When the system is powered on, it enters the Inactive State after it completes all the self tests. + +Some of the transitions in the state diagrams depend on the detection of the INDR = ONE status arriving in the incoming S3 (data). The LTU will decide that INDR = ONE, only if it detects this condition in six consecutive HDSL frames. + +#### **B.5.6.7.2.1 Inactive State** + +During the Inactive State the LTU transmitters are silent and LOSW = ONE. The LTU waits for the ACTREQ = ONE command, and then moves to the Activating State. + +#### **B.5.6.7.2.2 Activating State** + +During the Activating State the transmitted signal can be either S0, S1, S2 or S3. When the LTU enters this state from the Inactive State, it starts to transmit the S0 signal. When an LTU transceiver senses for the first time the S0 signal from the NTU, it starts the T-Act timer and activation proceeds as described in B.5.6.4. During the transmission of the S3 signal, if the HDSL frame synchronization is detected then LOSW = ZERO. If the LTU senses from the data arriving from the NTU that + +INDR = ONE, the LTU changes to the Active-Tx State. If INDC = ONE the LTU changes to the Active-Rx State. If the T-Act timer expires, the LTU changes to the Deactivated State. + +#### **B.5.6.7.2.3 Active-Rx State** + +During the Active-Rx State INDC = ONE, INDR = ZERO and the LTU transceiver is transmitting S3. At the same time the LTU is ready to receive data from the NTU. When the LTU senses from S3 arriving from the NTU that INDR = ONE, or when the T-Act timer expires, the LTU changes to the Active-Tx/Rx State. The LTU continues to monitor the frame sync according to Figure B.20. + +#### **B.5.6.7.2.4 Active-Tx State** + +During the Active-Tx State INDC = ZERO, INDR = ONE and the LTU is transmitting S3. At the same time the LTU is receiving S3 from the HDSL transceivers at the NTU. When INDC = ONE or when the T-Act timer expires, the LTU changes to the Active-Tx/Rx State. The LTU continues to monitor for frame sync according to Figure B.20. + +#### **B.5.6.7.2.5 Active State** + +Upon entering the Active-Tx/Rx State the T-Act timer is deactivated. The transmitted signal is S3 (data). + +If the HDSL frame synchronization is lost (LOSW = ONE), the LTU changes to the Pending Deactivation State. + +#### **B.5.6.7.2.6 Pending Deactivation State** + +During the Pending Deactivation State LOSW = ONE, and the transmitted signal is S3 (data). When the LTU enters this state, a 2 s timer is started. If the HDSL frame synchronization is regained then LOSW = ZERO and the LTU returns to the Active-Tx/Rx State. If the 2 s timer expires, then LOSWT = ONE and the LTU changes to the Deactivated State. + +#### **B.5.6.7.2.7 Deactivated State** + +During the Deactivated State, no energy is transmitted to the line (i.e. Silent) and LOSW = ONE. When the LTU enters this state it looks for signal power from the NTU. When no power is detected (LOS = ONE), a 1 s timer is started. When this timer expires (LOST = ONE), the LTU changes to the Inactive State. + +### **B.5.6.7.3 The HDSL synchronization state machine** + +See 5.6.5.3 for a description of the HDSL Synchronization State machine. + +#### **B.5.6.8 Regenerator related procedures** + +In order to achieve data transmission over distances that are greater than can be achieved by a single HDSL link, a regenerator (REG) is necessary. A REG capability is required to be supported where the 2D 8-state trellis code is employed only. + +A separate REG has to be provided for each pair. The REG consists of two parts, REG-R for interfacing with the LTU, and REG-C for interfacing with the NTU. An internal connection between the REG-R and REG-C provides communication between the REG-R and REG-C provides communicant between the two parts during start-up and normal operation. + +The flow diagram in Figure B.21 shows the start-up sequence for the link between the LTU and the NTU. Note that, while the flow diagram indicates the transmission of CS0 from the REG in response to the detection of CS0 from the LTU, the transmission of CS0 may be delayed until the recovered timing from the LTU is stabilized. + +![Sequence diagram of the start-up procedure with a regenerator (REG) between an LTU and an NTU. The diagram shows the exchange of signals like LOS, ACTREQ, CS0, RS0, RS3, CS3, indc, and indir. The LTU starts with LOS=1, then receives LOS=0 and ACTREQ=1. It sends Silent, CS0, and RS0 to the REG. The REG responds with LOS=0 and ACTREQ=1. The LTU then performs 'Transceiver activation (B.5.6.5)'. The REG sends Active=1 to the NTU. The NTU sends Active=1 to the LTU. The LTU sends RS3, CS3, indc, and indir to the REG. The REG forwards these to the NTU. Finally, Data transmission becomes Transparent.](baf8e707713cfcf1fd4e6aa38dd94597_img.jpg) + +T1529440-98 + +Sequence diagram of the start-up procedure with a regenerator (REG) between an LTU and an NTU. The diagram shows the exchange of signals like LOS, ACTREQ, CS0, RS0, RS3, CS3, indc, and indir. The LTU starts with LOS=1, then receives LOS=0 and ACTREQ=1. It sends Silent, CS0, and RS0 to the REG. The REG responds with LOS=0 and ACTREQ=1. The LTU then performs 'Transceiver activation (B.5.6.5)'. The REG sends Active=1 to the NTU. The NTU sends Active=1 to the LTU. The LTU sends RS3, CS3, indc, and indir to the REG. The REG forwards these to the NTU. Finally, Data transmission becomes Transparent. + +NOTE – The transmission of indc through to the NTU only occurs after both the remote and the network end links are active. Since one link may complete start-up before the other, the transmission of indc through to the NTU may be delayed at the REG or it may occur as soon as the remote link is active. + +**Figure B.21/G.991.1 – Start-up procedure with regenerator** + +### B.5.6.9 The pair identification mechanism for two-pair system + +The pair (path) identification procedure for CAP-HDSL is based on loop identification contained in the messages used to send Tomlinson coefficients as discussed in B.5.6.5.5. The NTU transceivers adopt the identification received from the LTU during this start-up phase. The multiplexing (demultiplexing) of the HDSL frames into (from) the core frame at the NTU adapts to this pair identification. + +## B.5.7 Operation and maintenance + +See 5.7, 5.7.1, 5.7.2, 5.7.3 and 5.7.4 for requirements concerning operation and maintenance, including the description of the messages to be supported by the core. The only exception concerns pair identification. The pair identification mechanism for a two-pair system is described in B.5.6.9. + +### B.5.7.1 Regenerator behaviour + +#### B.5.7.1.1 Response to LOS/LFA + +See 5.7.5.1 for the required regenerator response to LOS/LFA. + +#### B.5.7.1.2 Operation of loopback 1A + +The activation of loopback 1A in any subsystem of the transceiver is initiated by the LTU using the appropriate eoc message as described in 5.5. The loopback request may be initiated only after the HDSL link is active. + +The loopback request may be transmitted toward the REG as soon as signal S3 according to B.5.6 is transmitted in the direction LTU → NTU. After the eoc message has been detected in the REG the loopback is closed accordingly. + +If the link is already active, the control unit in the REG closes the loop as soon as the eoc message has been detected. The detailed procedure for reaching the synchronous loopback state is up to the vendor. (It may be necessary to reset the REG-C transceiver, so that its equalizer and echo canceller coefficients may converge under the loopback conditions.) A successfully closed loopback may be detected in the LTU by evaluating the valid received Z-bits or by other means. + +The loopback is transparent, i.e. the looped back signal is also transmitted toward the NTU. + +During an active loopback 1A, the operation of the HDSL overhead bits shall be as follows: + +- The eoc channel is not looped back but is fully operating between the LTU and the REG as described in B.5.5, as long as the messages sent by the LTU contain the REG address "10". When detecting any other address, the REG inserts the "Hold State" message with its own address in the direction REG → LTU. +- All indicator bits, except the REG specific bits hrp, rega, rrbe, which are operating normally, are looped back. + +To deactivate loopback 1A, the LTU transmits the "Return to Normal" message together with the address "10" in the eoc channel. After detecting this message, the REG control unit deactivates automatically the REG-C transceiver and cancels the loopback operation. + +If the HDSL link between the LTU and the REG is still active, the REG control unit immediately starts to activate the link between the REG and the NTU as described in B.5.6. + +The successful completion of the start-up procedure may be detected at the LTU by receipt of indr or by other means. + +## **B.5.8 Electrical characteristics of CAP-based transceivers** + +### **B.5.8.1 General** + +This subclause describes the electrical characteristics of a single HDSL transceiver. + +The electrical characteristics of the HDSL transceivers shall assure that the performance requirements of the various applications are met. In addition, the following specific electrical characteristics are required. + +Means should be provided to enable the testing of the electrical characteristics of a single transceiver. + +### **B.5.8.2 Transmitter/receiver impedance and return loss** + +The nominal driving point impedance of the transceiver line interface shall be 135 ohms. + +The minimum return loss with respect to 135 ohms, over the frequency band of 1 kHz to 1 MHz shall be as shown in Figure B.22 (16 dB from f1 to f2, with 20 dB/decade rise at lower frequencies and a 20 dB/decade drop at higher frequencies to a minimum of 0 dB). + +![Figure B.22/G.991.1 – Minimum return loss of transceiver. The graph shows Minimum return loss (dB) on the y-axis (0 to 15) versus Frequency (kHz) on a logarithmic x-axis (10 to 1000). The curve is flat at 0 dB until f1, then rises linearly to 15 dB at f1, remains flat at 15 dB until f2, then falls linearly to 0 dB at f2, and remains flat at 0 dB. Slopes are labeled 20 dB/decade. Below the graph is a table with columns 'Key', 'f1', and 'f2'.](7473436aa38da42cdf82205d416ec1d6_img.jpg) + +| Key | f1 | f2 | +|-----------------|----|-----| +| One-pair system | 62 | 390 | +| Two-pair system | 39 | 238 | + +Figure B.22/G.991.1 – Minimum return loss of transceiver. The graph shows Minimum return loss (dB) on the y-axis (0 to 15) versus Frequency (kHz) on a logarithmic x-axis (10 to 1000). The curve is flat at 0 dB until f1, then rises linearly to 15 dB at f1, remains flat at 15 dB until f2, then falls linearly to 0 dB at f2, and remains flat at 0 dB. Slopes are labeled 20 dB/decade. Below the graph is a table with columns 'Key', 'f1', and 'f2'. + +**Figure B.22/G.991.1 – Minimum return loss of transceiver** + +### B.5.8.3 Transceiver reference clock + +#### B.5.8.3.1 One-pair system clock + +The reference clock for transceiver for one-pair systems shall assure a symbol rate in the range of 386.667 kbaud $\pm$ 90 ppm. + +#### B.5.8.3.2 Two-pair system clock + +The reference clock for transceivers for two-pair systems shall assure a symbol rate in the range of 233.60 kbaud $\pm$ 110 ppm. + +### B.5.8.4 Transmitter output characteristics + +Unless otherwise specified, the following specifications apply with a resistive load impedance of 135 ohms. + +#### B.5.8.4.1 Total power + +##### B.5.8.4.1.1 Two-pair system total power + +The average transmit power at the transmitter output (excluding remote power feeding) shall be either 13 to 14 dBm (high power mode) or 6 to 8 dBm (low power mode) into a 135 ohms termination. The selection of the high and low power modes is described in B.5.6.5.2. + +##### B.5.8.4.1.2 One-pair system total power + +The average transmit power at the transmitter output (excluding remote power feeding) shall be either 15 to 16 dBm (high power mode) or 8 to 10 dBm (low power mode) into a 135 ohms termination. The selection of the high and low power modes is described in B.5.6.5.2. + +#### B.5.8.4.2 Power spectral density + +Figure B.23 is a template for the CAP HDSL transmit signal spectrum. The template gives the nominal passband power spectral density (PSD). At frequencies below f3 and above f4, as indicated by the dashed line, the template is accurate only at the critical frequencies indicated. The nominal shape of the transmit signal spectrum is the square root of a raised cosine with a nominal 15 percent excess bandwidth. The nominal 3 dB points on the spectrum are f2 and f5. This is referred to as the + +passband in this specification. The spectra of transceiver for one- and two-pair systems are centered around frequencies of 226.33 kHz and 138.30 kHz, respectively. + +![Figure B.23/G.991.1 – CAP HDSL transmit power spectral density. The graph shows transmit power spectral density (dB/Hz) relative to the passband (0 dB) versus frequency (kHz). The passband is flat at 0 dB between f3 and f4. Below f1, the power is at least -17 dB. Above f7, the power drops into a stop band (unacceptable region).](a470a6ac2c62c28490aa633071c565a9_img.jpg) + +Figure B.23/G.991.1 – CAP HDSL transmit power spectral density. The graph shows transmit power spectral density (dB/Hz) relative to the passband (0 dB) versus frequency (kHz). The passband is flat at 0 dB between f3 and f4. Below f1, the power is at least -17 dB. Above f7, the power drops into a stop band (unacceptable region). + +| Key | f1 | f2 | f3 | f4 | f5 | f6 | f7 | +|-----------------|------|-------|-------|--------|--------|--------|--------| +| Two-pair system | 3.98 | 21.50 | 39.02 | 237.58 | 255.10 | 272.62 | 297 | +| One-pair system | 4.00 | 33.00 | 62.00 | 390.67 | 419.67 | 448.67 | 489.02 | + +Figure B.23/G.991.1 – CAP HDSL transmit power spectral density. The graph shows transmit power spectral density (dB/Hz) relative to the passband (0 dB) versus frequency (kHz). The passband is flat at 0 dB between f3 and f4. Below f1, the power is at least -17 dB. Above f7, the power drops into a stop band (unacceptable region). + +**Figure B.23/G.991.1 – CAP HDSL transmit power spectral density** + +The signal power spectral density in the frequency band below f1 shall be at least 17 dB below the nominal signal power density in the passband. The signal power spectral density at frequencies above f7 shall conform to the requirements shown in Figure B.24. + +![Figure B.24/G.991.1 – Maximum out-of-band signal power. The graph shows maximum transmit power spectral density (dBm/Hz) versus frequency (kHz) on a logarithmic scale. The power is constant at -70 dBm/Hz from 100 kHz to f7, then decreases linearly to -120 dBm/Hz at 4 f7, and remains constant at -120 dBm/Hz up to 4000 kHz.](7cf299073e9754bfa29465321e13f68c_img.jpg) + +Figure B.24/G.991.1 – Maximum out-of-band signal power. The graph shows maximum transmit power spectral density (dBm/Hz) versus frequency (kHz) on a logarithmic scale. The power is constant at -70 dBm/Hz from 100 kHz to f7, then decreases linearly to -120 dBm/Hz at 4 f7, and remains constant at -120 dBm/Hz up to 4000 kHz. + +Figure B.24/G.991.1 – Maximum out-of-band signal power. The graph shows maximum transmit power spectral density (dBm/Hz) versus frequency (kHz) on a logarithmic scale. The power is constant at -70 dBm/Hz from 100 kHz to f7, then decreases linearly to -120 dBm/Hz at 4 f7, and remains constant at -120 dBm/Hz up to 4000 kHz. + +**Figure B.24/G.991.1 – Maximum out-of-band signal power** + +Within the band between the frequencies of f3 and f4, the spectral density (dBm/Hz) at any frequency shall be within $\pm 1$ dB of the average density within the band (this means that, for the two-pair transceivers, the power/Hz must be in the range of $-40 \pm 1.5$ dBm). In addition, for one-pair transceivers, the maximum spectral density at any frequency shall not exceed $-40$ dBm/Hz. + +The spectral density at f2 and f5 shall be $-3 \pm 1$ dB relative to the average spectral density in the band of f3 to f4. The spectral density at f1 and f6 shall be $-20 \pm 3.0$ dB relative the average spectral + +density in band of f3 to f4. In addition, the spectrum shall comply with the limitations given in Figure B.24. + +### B.5.8.5 Unbalance about earth + +#### B.5.8.5.1 Longitudinal conversion loss (LCL) + +The LCL is given by: + +$$LCL = 20 \log (e_l/e_m) \text{ dB}$$ + +where $e_l$ is the applied longitudinal voltage referenced to the building ground, and $e_m$ is the resultant metallic (transverse mode) voltage appearing across a 135 ohms termination. + +The LCL of the system shall meet the requirement shown in Figure B.25. + +![Figure B.25/G.991.1 – Minimum longitudinal conversion loss (LCL). The graph shows LCL (dB) on the y-axis (35 to 55) versus Frequency (kHz) on a logarithmic x-axis (1 to 1000). The curve rises from 38 dB at 10 kHz to 50 dB at f1, stays at 50 dB until f2, and then falls at 20 dB/decade. A key table below defines f1 and f2 for one-pair and two-pair systems.](33b4707b3be8c088007bd619bcfc8b10_img.jpg) + +| Key | f1 | f2 | +|-----------------|------|-----| +| One-pair system | 33 | 420 | +| Two-pair system | 21.5 | 255 | + +Figure B.25/G.991.1 – Minimum longitudinal conversion loss (LCL). The graph shows LCL (dB) on the y-axis (35 to 55) versus Frequency (kHz) on a logarithmic x-axis (1 to 1000). The curve rises from 38 dB at 10 kHz to 50 dB at f1, stays at 50 dB until f2, and then falls at 20 dB/decade. A key table below defines f1 and f2 for one-pair and two-pair systems. + +Figure B.25/G.991.1 – Minimum longitudinal conversion loss (LCL) + +See Figure 29 for a description of a measurement method for longitudinal conversion loss. For direct use of this test configuration, measurement shall be performed with the LTU powered up but inactive (no transmitted signal). + +#### B.5.8.5.2 Longitudinal output voltage + +The longitudinal component of the output signal shall have an r.m.s. voltage, in any 4 kHz equivalent bandwidth averaged over any 1 s period, < -50 dBV over the frequency range of f1 to f2 specified in Figure B.25. Compliance with this limitation is required with a longitudinal termination having an impedance of 100 ohms in series with 0.15 μF nominal. (For EMC requirements see 8.4). + +See Figure 25 for a description of a measurement method for longitudinal output voltage. For direct use of this test configuration, the IUT (LTU, NTU or REG) should be able to generate a signal in the absence of a signal from the far end. + +The ground reference for these measurements shall be the building ground. + +## **B.5.9 Performance of individual HDSL transceivers** + +### **B.5.9.1 Performance requirements** + +Performance limits for the overall system are defined for specific applications of which examples are given in Appendix I. The performance of the individual HDSL transceivers must be such that these overall performance limits are met. As neither the 1168 kbit/s or 2320 kbit/s signal of the individual transceivers is available at an external interface for testing, it is not considered feasible to test the performance of the individual HDSL transceivers. For the purpose of conformance, each HDSL system is required to have an individual performance such that the overall application performance requirements for the appropriate application is met. + +### **B.5.9.2 DLL physical models for laboratory testing** + +Some representative models of DLLs (test loops) for evaluating the performance of transceivers for transmission systems are defined in B.6.2. + +### **B.5.9.3 Jitter and wander** + +#### **B.5.9.3.1 General** + +The HDSL transmission system jitter and performance limits are specified for specific applications (see Appendix I) at the application interfaces for specific applications. The limits specified here are intended to ensure compatibility of LTUs and NTUs from different manufacturers, i.e. ensure that system performance limits are met by systems employing LTUs and NTUs from different manufacturers. + +The following limitations apply at transmission line interfaces of transceivers. However, due to the bidirectional transmission on the two-wire line and due to severe intersymbol interference, no well defined signal transitions are available on the two-wire signal. It is therefore necessary to provide reference clock outputs to enable the following requirements to be tested. + +The jitter limits given below must be satisfied regardless of the length of the local line, provided that it is covered by the transmission media characteristics of B.5.2. The scrambler specified in B.5.3.4 assures that, if the limits are met for one bit sequence, they will be met for all possible transmitted bit sequences. In this subclause, jitter is specified in terms of unit intervals (UI), which are equal to symbol intervals, at the nominal line symbol rates. The symbols rates and UIs are: + +- transceiver for one-pair system: 386.667 kbaud and UI = 2.586 µs +- transceiver for two-pair system: 233.600 kbaud and UI = 4.281 µs + +#### **B.5.9.3.2 Input jitter tolerance at the HDSL transceiver at the NTU** + +The NTU shall meet the performance objectives specified for specific applications (see Appendix I), with the following wander/jitter superimposed on the clock of the test signal source of the received signal, and with the received signal symbol rate at any rate in the permitted transceiver clock range specified in B.5.8.3 but with a variation of up to $\pm 25$ ppm. The wander/jitter shall have sinusoidal characteristics at the maximum amplitudes defined in Figure B.26 with the values specified in Table B.7 for single frequencies in the range of 0.1 Hz to f3. + +![Figure B.26/G.991.1 – Single frequency jitter and wander limitation. A graph showing Peak-to-peak jitter (UI) on the y-axis versus Jitter frequency (log scale) on the x-axis. The graph shows a piecewise linear function: a horizontal line at A1 from 0 to f1, a downward sloping line from f1 to f2 with a slope of 20 dB/decade, and a horizontal line at A2 from f2 to f3. The x-axis is labeled with 0, f0, f1, f2, and f3. The y-axis is labeled with A1 and A2.](5c2fb18df09421d12f6ba9370b90d925_img.jpg) + +Figure B.26/G.991.1 – Single frequency jitter and wander limitation. A graph showing Peak-to-peak jitter (UI) on the y-axis versus Jitter frequency (log scale) on the x-axis. The graph shows a piecewise linear function: a horizontal line at A1 from 0 to f1, a downward sloping line from f1 to f2 with a slope of 20 dB/decade, and a horizontal line at A2 from f2 to f3. The x-axis is labeled with 0, f0, f1, f2, and f3. The y-axis is labeled with A1 and A2. + +T1529490-98 + +**Figure B.26/G.991.1 – Single frequency jitter and wander limitation** + +**Table B.7/G.991.1 – Single frequency jitter/wander parameters** + +| | Peak amplitude | | Frequency | | | | +|-----------|-----------------------|------------------------|-----------|---------|-------|--------| +| | A1 | A2 | f0 | f1 | f2 | f3 | +| NTU input | 0.25 UI pp | 0.005 UI pp | 0.10 Hz | 0.20 Hz | 20 Hz | 20 kHz | +| LTU input | | 0.005 UI pp | | | 20 Hz | 20 kHz | + +### B.5.9.3.3 Output jitter limitations of an HDSL transceiver in an NTU + +With NTU transceiver received signal having the maximum wander/jitter at individual single frequencies given in Figure B.26, wander/jitter on the transmitted signal of the NTU towards the LTU shall conform to the following. [Note that with the add/delete function specified in B.5.4, the jitter superimposed on the NTU input (application interface) signal does not impact the NTU transceiver output signal jitter.] + +The maximum NTU output signal jitter shall be equal to or less than that indicated in Table B.8. B1 is measured with a bandpass filter having a lower cut-off frequency of f1 and an upper cut-off frequency of f2. B2 is measured with a similar filter where the cut-off frequencies are f2 and f3. Bandpass filters shall have rolloffs above and below cut-off frequencies of nominally 6 dB/octave. + +The maximum (peak) departure of the phase of the NTU transceiver output signal from its nominal difference (long-term average) from the phase of the NTU transceiver input (from the LTU) shall not exceed 0.2 UI. That is: + +$$\max |\Phi_{\text{inst.}} - \Phi_{\text{average}}| \leq 0,2 \text{ UI}$$ + +where: + +$\Phi_{\text{inst.}}$ = instantaneous phase of NTU transmitted signal relative to the average phase of the NTU received signal + +$\Phi_{\text{average}}$ = long-term average phase difference between NTU transmitted and received signals + +**Table B.8/G.991.1 – Maximum output jitter/wander** + +| | Maximum jitter | | Measurement filter parameters | | | +|-----|-----------------------|------------------------|--------------------------------------|------|--------| +| | B1 = f1-f2 | B2 = f2-f3 | f1 | f2 | f3 | +| NTU | 0.25 UI pp | 0.005 UI pp | 0.2 Hz | 2 Hz | 20 kHz | +| LTU | 0.25 UI pp | 0.005 UI pp | 0.2 Hz | 2 Hz | 20 kHz | + +**B.5.9.3.4 Input jitter tolerance at the HDSL transceiver at the LTU** + +The LTU shall meet the performance objectives specified for specific applications (see Appendix I), with wander/jitter as follows superimposed on the clock of the test signal source of the received signal, and with the received signal symbol rate at any rate in the permitted transceiver clock range specified in B.5.8.3 with a variation of up to ±25 ppm. The wander/jitter shall have sinusoidal characteristics at the maximum amplitudes defined in Figure B.26 with the values specified in Table B.7 for single frequencies in the range of 0.1 Hz to f3. (Note that the wander in the input signal is limited to the wander in the LTU output by the requirement in B.5.9.3.3 that the NTU output track the NTU input within 0.2 UI.) + +**B.5.9.3.5 Output jitter limitation of the HDSL transceiver at the LTU** + +The maximum jitter and wander on the transmitted signal of the LTU towards the NTU shall be as indicated in Table B.8. (Note that the transmitted bit stream is synchronized to a local clock in the LTU transceiver and therefore the wander is determined by the stability of the clock and the jitter is determined by countdown circuit used to derive the symbol rate clock.) + +**B.6 Common circuitry specification****B.6.1 Delay difference buffer** + +In order to compensate for any difference in total transmission time of the HDSL frames on different pairs, due to the pair differences described in 5.2.4.2, as well as to delays due to signal processing in the HDSL transceivers in the LTU and NTU and possible REG, a delay difference buffer shall be implemented in the common circuitry. The function of this delay difference buffer is to align the HDSL frames so that the core frames can be correctly reassembled. This buffer should be capable of absorbing a maximum delay difference of 60 μs. + +**B.6.2 Laboratory performance measurement tests****B.6.2.1 General** + +See 6.3.1 for general requirements. Figure 32 is showing the defined models of DLLs (test loops). The value Y (insertion loss in dB at 150 kHz) for CAP systems is to be found in Table B.9. + +**Table B.9/G.991.1 – Test sequence** + +| N | Loop | Direction | Comment | +|----|-------------|---------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------| +| 1 | #1 (Note 1) | Forward | Y = 0 dB; Test noise of B.6.2.3.1 with N1 = 300 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 30 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 2 | #2 | Forward | Y = Y1; (Note 2) Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 3 | #3 | Forward | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 4 | #3 | Reverse | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 5 | #4 | Forward | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 6 | #4 | Reverse | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 7 | #5 | Forward | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 8 | #6 | Forward | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 9 | #6 | Reverse | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 10 | #7 | Forward | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 11 | #7 | Reverse | Y = Y1; Test Noise of B.6.2.3.2 and of B.6.2.3.1 with N1 = 100 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 10 $\mu\text{V}/\sqrt{\text{Hz}}$ | +| 12 | #8 | Forward | Y = Y1; Common mode rejection test of B.6.2.5 | +| 13 | Note 3 | Forward
and
Reverse | Y = Y2; Test noise of B.6.2.3.1 with N1 = 300 $\mu\text{V}/\sqrt{\text{Hz}}$ and N2 = 30 $\mu\text{V}/\sqrt{\text{Hz}}$
Worst path of tests 1 to 11 | +| 14 | Note 3 | Note 3 | Y = Y3; No added impairment; Worst path of tests 1 to 11, $\text{BER} < 10^{-8}$ | +| 15 | #2 | Forward | Y = Y1; Impulse test as described in B.6.2.4.4 | +| 16 | As B.6.2.6 | Forward | Micro interruption test as described in B.6.2.6 | + +NOTE 1 – Test loop = #1 means that the path under test shall be connected with test loop #1 as defined in Figure 32. The path not under test shall be connected with a dummy loop, normally loop #1. + +NOTE 2 – Y1 = 23 dB for the one-pair system and Y1 = 31 dB for the two-pair system, except that, for determining performance in the presence of truncated Gaussian noise (B.6.2.3.2), in which case, Y1 shall be reduced by 1 dB. Y2 = Y1 – 10 dB and Y3 = Y1 + 3 dB. + +NOTE 3 – The tests are carried out on the worst path in the worst direction from tests 1 to 11, with a dummy loop for the remaining path. If there are no errors, then loop #2 forward for path A is taken as default. + +NOTE 4 – The tests 1 to 15 shall be carried out on all pairs. In the case of a fractionally installed two-pair HDSL system, the tests shall be carried out only on the installed pair. + +### **B.6.2.2 Test configuration** + +See 6.3.2 and Figure 34 for a representative test arrangement. + +The proposed test sequence for the HDSL system is shown in Table B.9. + +Note that two distinct classes of added disturbance are injected: Test noise (specified in B.6.2.3.1 and B.6.2.3.2) and Impulses (defined in 6.3.4.1). A further test (specified in 6.3.6) tests the immunity of the system under test to micro interruptions. + +### **B.6.2.3 Test procedure with random noise source** + +Most noise on local network lines can be represented by an artificial noise source as described below. Tests shall be as indicated in Table B.9. Tests shall be carried out with the injection circuit described in 6.3.3.3 and noise source and test loop calibration shall be as specified in 6.3.3.4. + +#### **B.6.2.3.1 Low crest factor noise** + +This artificial noise is intended to represent intersystem and intrasystem crosstalk. It is defined to assure that essentially the same performance will be obtained in laboratory measurements using noise sources from different test set vendors. + +See 6.3.3.1 and 6.3.3.2 for a description of the low crest factor shaped noise. + +#### **B.6.2.3.2 Truncated Gaussian noise** + +Truncated Gaussian noise is defined to have a nominally Gaussian amplitude distribution. Noise having a Gaussian amplitude distribution is representative of worst case crosstalk. However, the amplitude distribution may be truncated at a crest factor of 5.0. + +The noise density shall be $10 \mu\text{V}/\sqrt{\text{Hz}}$ and nominally flat from 10 to 240 kHz. Tests using the noise source described in 6.3.3 is adequate for evaluating the effects of an increased magnitude at frequencies below 10 kHz. + +### **B.6.2.4 Test procedure for impulse noise** + +#### **B.6.2.4.1 Impulse noise test waveform** + +See 6.3.4.1 for the specification of impulse noise. + +#### **B.6.2.4.2 Impulse noise test measurement** + +The test impulse shall be applied to the system under test as specified in 6.3.4.3 using the test configuration described in 6.3.4.2. The performance criteria for transceivers for one-pair and two-pair systems shall be as specified in Table 21 except that the value of Y shall be 23 dB and 31 dB, respectively. + +#### **B.6.2.4.3 Impulse noise test performance requirements** + +Table 21 gives the maximum bit error ratio for the three levels of impulse noise. The peak-to-peak amplitude of the test impulse noise is given in mV (and in dB relative to a reference level of 320 mV) measured at the output of the shunt injection circuit, loaded with a 67.5 Ohms resistor. + +### **B.6.2.5 Common mode rejection test** + +See 6.3.5 for common mode rejection requirements. + +### **B.6.2.6 Micro interruption test** + +See 6.3.6. + +## **B.7 Power feeding** + +See clause 7 for power feeding requirements. + +## **B.8 Environmental requirements** + +See clause 8 for environmental requirements. + +# **APPENDIX I** + +## **Application specific examples** + +### **I.1 Application specific requirements for ISDN PRA with 2048 kbit/s** + +#### **I.1.1 Mapping of 2048 kbit/s to HDSL** + +As described in 5.4 (Frame Structure) the 2048 kbit/s application data has to be mapped into a core frame with 144 bytes and 500 $\mu$ s length. The data at the application interfaces T and V3 (see Figures 1 and 2 and Recommendation G.962 [1]) contain only 128 bytes per 500 $\mu$ s and the unused bytes have to be filled up with 16 stuffing bytes, called Y- and R-bytes and containing all binary ONEs, as shown in Figure 6 b). The use of the stuffing bytes for other purposes, e.g. forward error correction is for further study. To achieve total decoupling of the HDSL frame from the core frame and a minimum signal delay the location of time slot 0 within the core frame is arbitrary. This means that, with exception of the location occupied by the Y- and R-stuffing bytes, the first bit of time slot 0 may occur anywhere in the frame. In addition loss of frame alignment at the application interfaces T and V3 does not lead to a resynchronization of the HDSL transceivers, because the core frame is transmitted totally transparent through the HDSL transceiver systems. + +The bits $Z_{m9}$ to $Z_{m48}$ in the HDSL frame are unused and set to ONE. + +#### **I.1.2 Mapping of HDSL maintenance functions to the interface** + +The application dependent maintenance functions, the definition of the function elements (FE) for the signalling across the application interfaces and the coding of the FE, using the E-, A-, Sa5- and Sa6-bits of time slot 0 in the application frame, are defined in clause 9/G.962 [1] for the V3 reference point and in Table 1/I.431 [3] for the T reference point. All these functions have to be performed in the interface blocks according to Figure 1 by evaluating frame alignment, signal patterns and CRC-4 error detection. + +For the detection of the states "Normal operation of the DS", "LOS/LFA at line side of the NT1" and "LOS at the line side of the LT" the maintenance functions "LOS/LFA at line side of the NTU" and "Active indication (INDR)", which are created by the common core at the NTU, respectively "LOS/LFA at LTU line side" and "Active indication (INDC)", which are created by the common core at the LTU, have to be taken into account. + +The access digital section shall be considered operational when all the transceiver pairs have indicated completion of the activation procedure (see 5.6 or B.5.6) and correct pair identification has been achieved in the core frame, as described in 6.2 or B.5.6.9, and no further failure condition is detected. If one of the transceiver pairs is indicating non-operational condition or incorrect pair identification, the access digital section shall be considered non-operational. + +The only maintenance function of this application which has to be achieved by the common core is "Loopback 1 command" as described in Table I.1. + +**Table I.1/G.991.1 – Loopback** + +| Function | Localization | Controlled by | Requested via | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------|---------------------------------|----------------------| +| Loopback 1 | As near as possible to the line | OAM in block M in LTU
(Note) | V3 interface | +| NOTE – When loopback 1 is requested via V3 interface a complete and transparent loopback shall be activated in all HDSL transceivers at the line side of the LTU. These loopbacks are managed by an OAM function inside the functional block M in the LTU. | | | | + +**I.1.3 Performance****I.1.3.1 Performance specification** + +The overall performance must be such that the performance limits given in Recommendation G.826 [B9] can be met. For the purpose of conformance, an HDSL transmission system is required to meet the specific laboratory performance tests that are defined in 6.3 or B.6.2. + +**I.1.3.2 Signal transfer delay** + +The one-way signal transfer delay, which is the mean value of the delay time in both directions of transmission between the T and V3 reference points as defined in Recommendation G.962 [1], shall not exceed 1250 µs, the allocation for a 2B1Q HDSL system shall be as follows: + +| | | +|------|----------| +| LTU | ≤ 450 µs | +| NTU | ≤ 450 µs | +| REG | ≤ 200 µs | +| Line | ≤ 150 µs | + +**I.1.3.3 Clock specification for external interfaces****I.1.3.3.1 NTU clock tolerance** + +The frequency of the free running NTU clock is 2048 kHz with a maximum tolerance ±50 ppm. + +**I.1.3.3.2 LTU clock tolerance** + +The frequency of the free running LTU clock is 2048 kHz with a maximum tolerance ±50 ppm. + +**I.1.3.3.3 Jitter specification** + +The tolerance to input jitter as well as the jitter transfer limitation are defined in terms of amplitude and frequency of sinusoidal input jitter which, when modulating a $2^{15}-1$ pseudo-random bit sequence within time slots 1 to 31 of the bit stream, should not cause bit errors in the transmission system or jitter at the relevant output which is in excess of limits defined below. This test method is used for convenience of testing and is not, in itself, intended to be representative of the type of jitter to be found in practical applications. + +The tolerable input jitter is given in Figure I.1 with the values of Table I.2. The output jitter limits given in Table I.3 shall be met when applying the tolerable jitter to the relevant input, where B1 is measured with a bandpass having a upper cut-off frequency of f4 and a lower cut-off frequency of f1, whilst B2 is measured with the same high cut-off frequency but with a low cut-off frequency increased to f3. + +![Figure I.1/G.991.1: Lower limit of maximum tolerable input jitter and wander. The graph shows Jitter (UIpp) on the y-axis with levels A0, A1, A2 and 0. The x-axis shows Jitter frequency (log scale) with points f0, f1, f2, f3, f4. The curve starts at (0, A0), stays flat to (f0, A0), slopes down to (f1, A1), stays flat to (f2, A1), slopes down to (f3, A2), and stays flat to (f4, A2).](c8963539c3bd0eb59ea725eec790dc18_img.jpg) + +Figure I.1/G.991.1: Lower limit of maximum tolerable input jitter and wander. The graph shows Jitter (UIpp) on the y-axis with levels A0, A1, A2 and 0. The x-axis shows Jitter frequency (log scale) with points f0, f1, f2, f3, f4. The curve starts at (0, A0), stays flat to (f0, A0), slopes down to (f1, A1), stays flat to (f2, A1), slopes down to (f3, A2), and stays flat to (f4, A2). + +**Figure I.1/G.991.1 – Lower limit of maximum tolerable input jitter and wander** + +**Table I.2/G.991.1 – Parameter values for input jitter tolerance at inputs** + +| Interface | Parameter | Peak-to-peak amplitude | | | Frequency | | | | | +|-------------|-----------|------------------------|------------------|------------------|-----------|----|------|-----|-----| +| | | A0 | A1 | A2 | f0 | f1 | f2 | f3 | f4 | +| At T input | Value | – | 1.1 | 0.11 | – | – | 40 | 0.4 | 100 | +| At V3 input | Value | 20.5 | 0.9 | 0.18 | 12 | 20 | 3600 | 18 | 100 | +| | Units | UI pp | UI pp | UI pp | μHz | Hz | Hz | kHz | kHz | + +NOTE 1 – UIpp = Unit Interval peak-peak. $1 \text{ UI}_{pp} = 1/2048 \text{ kHz} = 488 \text{ ns}$ for the ISDN PRA application. + +NOTE 2 – The values for the T-interface input are taken from Recommendation I.431 [3] as required by Recommendation G.962 [1]. + +NOTE 3 – The values for the V3-interface input are taken from Recommendation I.431 [3], but reduced by 10% margin for jitter accumulation in the HDSL transmission system. + +**Table I.3/G.991.1 – Maximum permitted values of output jitter** + +| Interface | Parameter | Maximum permissible jitter | | Measurement bandpass parameters (high pass part has first order slope) | | | +|--------------|-----------|----------------------------|------------------|------------------------------------------------------------------------|--------|-----| +| | | B1; (f1-f4) | B2; (f3-f4) | f1 | f3 | f4 | +| At T output | Value | 1.0 | 0.2 | 20 | 18 000 | 100 | +| At V3 output | Value | 1.2 | 0.2 | 20 | 700 | 100 | +| | Units | UI pp | UI pp | Hz | Hz | kHz | + +NOTE 1 – The values for the output at T-interface are taken from Recommendation I.431 [3]. + +NOTE 2 – The values for the output at V3-interface are taken from Recommendation I.431 [3], but increased by 10% for jitter accumulation in the HDSL transmission system in lower frequency area and based on high Q transmission network following. + +#### I.1.3.3.4 Wander specification + +The maximum wander that may be experienced at the output of an HDSL system, expressed in MTIE, shall not exceed the values given in Table I.4. The resultant overall specification is illustrated in Figure I.2. + +**Table I.4/G.991.1 – Maximum permitted values of output wander** + +| MTIE | Observation Interval | +|-----------------------------------|--------------------------| +| 732 ns | $0.05 < \tau \leq 100$ s | +| $13 \tau - 568$ ns | $100 < \tau \leq 200$ s | +| 2000 ns | $200 < \tau \leq 2000$ s | +| $433 \tau ^{0.2} + 0,01 \tau $ ns | $\tau > 2000$ s | + +![Figure I.2/G.991.1 – Maximum permitted values of output wander expressed in MTIE. This is a log-log plot showing MTIE (ns) on the y-axis versus Observation interval (s) on the x-axis. The y-axis ranges from 100 to 10,000 ns, and the x-axis ranges from 0.01 to 100,000 s. The plot shows a piecewise linear specification: a horizontal line at 732 ns from 0.05 s to 100 s; a linear increase from 100 s to 200 s, reaching 2000 ns; a horizontal line at 2000 ns from 200 s to 2000 s; and a linear increase on the log-log scale for observation intervals greater than 2000 s. Data points are marked with diamonds along the specification lines.](3aa4b7502e8f19d87e2cb8f36ed86c1a_img.jpg) + +Figure I.2/G.991.1 – Maximum permitted values of output wander expressed in MTIE. This is a log-log plot showing MTIE (ns) on the y-axis versus Observation interval (s) on the x-axis. The y-axis ranges from 100 to 10,000 ns, and the x-axis ranges from 0.01 to 100,000 s. The plot shows a piecewise linear specification: a horizontal line at 732 ns from 0.05 s to 100 s; a linear increase from 100 s to 200 s, reaching 2000 ns; a horizontal line at 2000 ns from 200 s to 2000 s; and a linear increase on the log-log scale for observation intervals greater than 2000 s. Data points are marked with diamonds along the specification lines. + +**Figure I.2/G.991.1 – Maximum permitted values of output wander expressed in MTIE** + +The timing reference for the MTIE measurement shall be the same as used as a reference for the 2048 Mbit/s pseudo random test sequence generator. The pseudo random test sequence shall be $2^{15}-1$ according to Recommendation O.151. + +NOTE 1 – Transmission systems designed according to editions 1 to 3 of ETR 152 may cause higher values for wander and will therefore not be suited for applications that are sensitive to wander. + +NOTE 2 – In order to determine the maximum wander amplitude produced by a HDSL system, the network clock frequency at the input of the system has to be varied in the range of $\pm 50$ ppm. It is recommended to use a clock offset resolution of $\leq 1$ ppm to measure the wander accurately. + +NOTE 3 – This value shall also be met in the presence of a regenerator. + +#### I.1.3.4 Laboratory performance measurement + +It is assumed that the performance can be evaluated at the application interface. The test arrangement and procedures of 6.3 or B.6.2 shall be used. + +## I.2 Application specific requirements for the European 2048 kbit/s digital unstructured leased line (D2048U) + +### I.2.1 Application interfaces + +#### I.2.1.1 Application interface at the customer side + +The application interface at the customer side shall be according to ETS 300 418 [B6] and ETS 300 247 [B5]. + +#### I.2.1.2 Application interface at the network side + +The application interface at the network side is a 2048 kbit/s interface according to Recommendation G.703 [B10]. + +### I.2.2 Mapping of the D2048U signal to HDSL + +As described in 5.4 the application data having a nominal bit rate of 2048 kbit/s with maximum tolerance of $\pm 50$ ppm shall be mapped bit sequence independently into a core frame with 144 bytes and 500 $\mu$ s length. The data at the application interface at the customer side contain only 128 bytes per 500 $\mu$ s. The unused bytes shall be filled up with 16 stuffing bytes called Y- and R-bytes and contain all binary ONEs, as shown in Figure 6 b). The use of the stuffing bytes for other purposes, e.g. forward error correction is for further study. + +The bits $Z_{m9}$ to $Z_{m48}$ in the HDSL frame are unused and shall be set to ONE. + +### I.2.3 Mapping of HDSL maintenance functions to the interface + +The access digital section shall be considered operational when all of the transceiver pairs have indicated completion of the activation procedure (see 5.6 or B.5.6), correct pair identification has been achieved in the core frame, as described in 6.2 or B.5.6.9, and no further failure condition is detected. If one of the transceiver pairs is indicating non-operational condition or incorrect pair identification, the access digital section shall be considered non-operational. + +The fact that the D2048U signal is unstructured makes it impossible for the HDSL core to map any operation and maintenance information into or out of the payload because the HDSL system does not have any information about the contents or the internal structure of the transmitted data. + +The only information the core can get is "LOS at the application interface of LTU" and "LOS at the application interface of NTU". When LOS at the application interface of NTU or LTU is detected, an "All ONEs" signal shall be transmitted to the far end of the HDSL system. At the same time bit 15 of the HDSL frame ("losd") shall be set to ZERO as shown in Table I.5. + +**Table I.5/G.991.1 – LOS at the application interface of LTU and NTU** + +| Leased line input condition | Action | +|-----------------------------------------|---------------------------| +| LOS at the application interface of LTU | losd = 0 in HOH (LTU/NTU) | +| LOS at the application interface of NTU | losd = 0 in HOH (NTU/LTU) | + +The mapping of LOS/LFA at the line side of LTU, NTU, and both sides of REG to the application interface is shown in Table I.6. + +**Table I.6/G.991.1 – Mapping of maintenance functions to the application interfaces** + +| Condition on one (or more) pair(s) | Message towards the application interface of | | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------|------------| +| | NTU | LTU | +| LOS/LFA at LTU line side | Note | AIS | +| LOS/LFA at NTU line side | Note | AIS | +| LOS/LFA at REG-R | Note | AIS | +| LOS/LFA at REG-C | Note | AIS | +| NOTE – As long as the HDSL system is not in the full operating state, i.e. not all of the HDSL transceivers are in the Active-Rx/Tx state, the signal towards the application interface of the NTU is not defined. | | | + +**I.2.4 Performance****I.2.4.1 Performance specification** + +The overall performance shall be such that the performance limits defined in Recommendation G.826 [B9] can be met. + +**I.2.4.2 Signal transfer delay** + +The one-way signal transfer delay between the application interfaces shall not exceed 1250 µs. This shall be calculated as the mean delay for both directions. The allocation for a 2B1Q HDSL system shall be as follows: + +| | | +|------|----------| +| LTU | ≤ 450 µs | +| NTU | ≤ 450 µs | +| REG | ≤ 200 µs | +| Line | ≤ 150 µs | + +**I.2.4.3 Clock specification for external interfaces****I.2.4.3.1 NTU clock tolerance** + +The frequency of the free running NTU clock shall be 2048 kHz with a maximum tolerance of ±50 ppm. + +**I.2.4.3.2 LTU clock tolerance** + +The frequency of the free running LTU clock shall be 2048 kHz with a maximum tolerance of ± 50 ppm. + +**I.2.4.3.3 Jitter specification** + +The tolerance to input jitter as well as the jitter transfer limitation are defined in terms of the amplitude and frequency of sinusoidal input jitter which, when modulating a $2^{15}-1$ pseudo random test sequence of the 2048 kbit/s bit stream at the nominal rate and with tolerances of +50 ppm and -50 ppm, shall not cause bit errors in the transmission system or jitter at the relevant output in excess of the limits defined below. This test method is used for convenience of testing and is not, in itself, intended to be representative of the type of jitter to be found in practice. + +The tolerable input jitter is given in Figure I.1 (see I.1.3.3.3) with the values of Table I.7. The output jitter limits given in Table I.8 shall be met when applying the tolerable jitter to the relevant input. + +**Table I.7/G.991.1 – Parameter values for input jitter tolerance at inputs** + +| Application interface | Parameter | Peak-to-peak amplitude | | | Frequency | | | | | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|------------------------|------------------|------------------|-----------|----|------|------|-----| +| | | A0 | A1 | A2 | f0 | f1 | f2 | f3 | f4 | +| At NTU (input) | Value | – | 1.1 | 0.11 | – | – | 4 | 0.04 | 100 | +| At LTU (input) | Value | – | 1.35 | 0.18 | – | 20 | 2400 | 18 | 100 | +| | Units | – | UI pp | UI pp | – | Hz | Hz | kHz | kHz | +| NOTE 1 – UI pp = Unit Interval peak-peak. 1 UI pp = $\frac{1}{2048}$ kHz = 488 ns for the D2048U application.
NOTE 2 – The values for the NTU input are taken from ETS 300 247 [B5].
NOTE 3 – The values for the LTU input are taken from Recommendation G.823 but reduced by 10% margin for jitter accumulation in the HDSL transmission system. | | | | | | | | | | + +**Table I.8 G.991.1 – Maximum permitted values of output jitter** + +| Application interface | Parameter | Maximum permissible jitter | | Measurement bandpass parameters (high pass part has first order slope) | | | +|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|----------------------------|------------------|------------------------------------------------------------------------|--------|-----| +| | | B1; (f1-f4) | B2; (f3-f4) | f1 | f3 | f4 | +| At NTU output | Value | 1.5 | 0.2 | 20 | 18 000 | 100 | +| At LTU output | Value | 0.3 | 0.15 | 20 | 700 | 100 | +| | Units | UI pp | UI pp | Hz | Hz | kHz | +| NOTE 1 – The values for the NTU output are taken from ETS 300 247 [B5].
NOTE 2 – The values for the LTU output are based on the input at NTU, but increased for jitter accumulation in the HDSL transmission system in the lower frequency area and based on high Q transmission network following. | | | | | | | + +#### I.2.4.4 Laboratory performance measurements + +It is assumed that the performance can be evaluated at the application interface. The test arrangement and procedures of 6.3 or B.6.2 shall be used. + +### I.3 Application specific requirements for the European 2048 kbit/s digital structured leased line (D2048S) + +#### I.3.1 Application interfaces + +##### I.3.1.1 Application interface at the customer side + +The application interface at the customer side shall be according to ETS 300 418 [B6] and ETS 300 419 [B7], 5.1.7.2. + +##### I.3.1.2 Application interface at the network side + +The application interface at the network side is a 2048 kbit/s interface according to Recommendation G.703 [B10]. If the structure information is handled in the NTU and/or LTU then the relevant function shall be implemented as defined in Recommendations G.704 [B11] and G.706 [B12]. + +### I.3.2 Mapping of the D2048S signal to HDSL + +As described in 5.4, the application data having a nominal bit rate of 2048 kbit/s with maximum tolerance of $\pm 50$ ppm shall be mapped bit sequence independently into a core frame with 144 bytes and 500 $\mu$ s length. The data at the application interface at the customer side contain only 128 bytes per 500 $\mu$ s. The unused bytes shall be filled up with 16 stuffing bytes called Y- and R-bytes and containing all binary ONEs, as shown in Figure 6 b). The use of the stuffing bytes for other purposes e.g. forward error correction is for further study. + +The bits $Z_{m9}$ to $Z_{m48}$ in the HDSL frame are unused and shall be set to ONE. + +### I.3.3 Mapping of HDSL maintenance functions to the interface + +The access digital section shall be considered operational when all of the transceiver pairs have indicated completion of the activation procedure (see 5.6 or B.5.6), correct pair identification has been achieved in the core frame, as described in 6.2 or B.5.6.9, and no further failure condition is detected. If one of the transceiver pairs is indicating non-operational condition or incorrect pair identification, the access digital section shall be considered non-operational. + +The mapping of LOS/LFA at the line side of LTU, NTU, and both sides of the REG to the application interface is shown in Table I.9. + +**Table I.9/G.991.1 – Mapping of maintenance functions to the application interfaces** + +| Condition on one (or more) pair(s) | Message towards the application interface of | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------|--------| +| | NTU | LTU | +| LOS/LFA at LTU line side | Note 1 | Note 2 | +| LOS/LFA at NTU line side | Note 1 | Note 2 | +| LOS/LFA at REG-R | Note 1 | Note 2 | +| LOS/LFA at REG-C | Note 1 | Note 2 | +| NOTE 1 – As long as the HDSL system is not in the full operating state, i.e. not all of the HDSL transceivers are in the Active-Rx/Tx state, the signal towards the application interface of the NTU is not defined. | | | +| NOTE 2 – The message sent towards the application interface of the LTU shall either be AIS or AUXP dependent on the requirement of the network operator. | | | + +Table I.10 shows how to achieve a complete and transparent loopback in the LTU. + +**Table I.10/G.991.1 – Loopback in the LTU** + +| Function | Localization | Controlled by | Requested via | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------|-----------------------|----------------------------------| +| Loopback 1 | As close as possible to the line | OAM in block M in LTU | The application interface of LTU | +| NOTE 1 – The use of this loopback is network dependent. | | | | +| NOTE 2 – When the loopback 1 is requested via the application interface of the LTU a complete and transparent loopback shall be activated in all HDSL transceivers on the line side of the LTU. These loopbacks are managed by an OAM function inside the functional block M in the LTU. | | | | + +### **I.3.4 Performance** + +#### **I.3.4.1 Performance specification** + +The overall performance shall be such that the performance limits defined in Recommendation G.826 [B9] can be met. + +#### **I.3.4.2 Signal transfer delay** + +The one-way signal transfer delay between the application interfaces shall not exceed 1250 $\mu\text{s}$ . This shall be calculated as the mean delay for both directions. The allocation for a 2B1Q HDSL system shall be as follows: + +| | | +|------|------------------------| +| LTU | $\leq 450 \mu\text{s}$ | +| NTU | $\leq 450 \mu\text{s}$ | +| REG | $\leq 200 \mu\text{s}$ | +| Line | $\leq 150 \mu\text{s}$ | + +#### **I.3.4.3 Clock specification for external interfaces** + +##### **I.3.4.3.1 NTU clock tolerance** + +The frequency of the free running NTU clock shall be 2048 kHz with a maximum tolerance of $\pm 50$ ppm. + +##### **I.3.4.3.2 LTU clock tolerance** + +The frequency of the free running LTU clock shall be 2048 kHz with a maximum tolerance of $\pm 50$ ppm. + +##### **I.3.4.3.3 Jitter specification** + +The tolerance to input jitter as well as the jitter transfer limitation are defined in terms of the amplitude and frequency of sinusoidal input jitter which, when modulating a $2^{15}-1$ pseudo random test sequence within time slots 1 to 31 of the 2048 kbit/s bit stream at the nominal bit rate and with tolerances of $+50$ ppm and $-50$ ppm, shall not cause bit errors in the transmission system or jitter at the relevant output in excess of the limits defined below. This test method is used for convenience of testing and is not, in itself, intended to be representative of the type of jitter to be found in practice. + +The tolerable input jitter is given in Figure I.1 (see I.1.3.3.3) with the values of Table I.11. The output jitter limits given in Table I.12 shall be met when applying the tolerable jitter to the relevant input. + +**Table I.11/G.991.1 – Parameter values for input jitter tolerance at inputs** + +| Application interface | Parameter | Peak-to-peak amplitude | | | Frequency | | | | | +|-----------------------|-----------|------------------------|------------------|------------------|-----------|----|------|------|-----| +| | | A0 | A1 | A2 | f0 | f1 | f2 | f3 | f4 | +| at NTU (input) | Value | – | 1.1 | 0.11 | – | – | 4 | 0.04 | 100 | +| at LTU (input) | Value | – | 1.35 | 0.18 | – | 20 | 2400 | 18 | 100 | +| | Units | – | UI pp | UI pp | – | Hz | Hz | kHz | kHz | + +NOTE 1 – UIpp = Unit Interval peak-peak. $1 \text{ UI}_{\text{pp}} = \frac{1}{2048} \text{ kHz} = 488 \text{ ns}$ for the D2048S application. +NOTE 2 – The values for the NTU input are taken from ETS 300 419 [B7]. +NOTE 3 – The values for the LTU input are taken from Recommendation G.823 but reduced by 10% margin for jitter accumulation in the HDSL transmission system. + +**Table I.12/G.991.1 – Maximum permitted values of output jitter** + +| Application interface | Parameter | Maximum permissible jitter | | Measurement bandpass parameters (high pass part has first order slope) | | | +|-----------------------|-----------|----------------------------|------------------|------------------------------------------------------------------------|--------|-----| +| | | B1; (f1-f4) | B2; (f3-f4) | f1 | f3 | f4 | +| at NTU output | Value | 1.5 | 0.2 | 20 | 18 000 | 100 | +| at LTU output | Value | 0.3 | 0.15 | 20 | 700 | 100 | +| | Units | UI pp | UI pp | Hz | Hz | kHz | + +NOTE 1 – The values for the NTU output are taken from ETS 300 419 [B7]. +NOTE 2 – The values for the LTU output are based on the input at NTU, but increased for jitter accumulation in the HDSL transmission system in the lower frequency area and based on high Q transmission network following. + +#### I.3.4.4 Laboratory performance measurements + +It is assumed that the performance can be evaluated at the application interface, avoiding the need for test access to the individual data channels. The test arrangement and procedures of 6.3 or B.6.2 shall be used. + +### I.4 Application specific requirements for fractional installation + +#### I.4.1 Mapping of fractional services to HDSL + +##### I.4.1.1 Overview of mapping procedure + +The fractional installation application interface is based on Recommendation G.704 [B11]. + +The fractional installation application of HDSL provides reduced access capability for the case where not all HDSL transceivers are equipped. The core frame of 144 bytes and 500 µs length, described in 5.4 (frame structure) is mapped onto one, two or three parallel HDSL frames, depending on the bit rate (784 kbit/s or 1168 kbit/s) and number of the equipped HDSL transceivers. If mapping option according to Figure 6 c) is implemented, in which the HDSL core frame is synchronized to the + +application frame, with TS0 being inserted in the first payload position in the HDSL frame, then the possibility exists for transparent transmission of a fractionally filled application frame, and also for partial operation of the system in the case of failure of transmission on one or more of the pairs. + +An external data interface (for example, ISO 2110 [B13]) and pre-processing functions may accept data at an aggregate bit rate of $(n \times 64)$ kbit/s and map it into the 2048 kbit/s application interface frame. An optional time slot interchange block allows the implementation of complex applications such as point-to-multipoint operation or the transmission of contiguous blocks of channels on each HDSL pair. (These functions are outside the scope of this Recommendation). + +The mapping of the core frame into the HDSL frame follows in the normal fashion, with the exception that not all the pairs need be equipped. This mapping process is illustrated in Figures I.3 and I.4. + +Note that with this mapping, partial operation of a fractionally installed three-pair system is possible. + +![Figure I.3/G.991.1 – Mapping process for fractional installation. The diagram shows the flow of data from an external interface through various processing blocks to HDSL transceivers. The process starts with an (n x 64) kbit/s data interface leading to an 'Application frame' block. This can be a 'Partially filled application frame' or pass through an 'Optional TimeSlot Interchange' block. It then enters the 'Interface (I)' section as a 'Partially filled application frame'. Next is the 'Mapping and Maintenance (M)' section, which contains 'Application frame' and 'Core frame' blocks. The data then enters the 'Common Circuitry (C)' section, which has two parallel paths: one for a '(Three-pair)' system and another for a '(Two-pair)' system. Both paths contain 'Core frame' and 'HDSL frames' blocks. Finally, the data is sent to 'HDSL Transceivers (H)' represented by boxes with an 'H' and signal lines.](da87c1b628b63a046d8a0d0fc2c058ea_img.jpg) + +The diagram illustrates the mapping process for fractional installation, showing the flow of data from an external interface through various processing blocks to HDSL transceivers. + +**Flow Description:** + +- Input:** $(n \times 64)$ kbit/s data interface. +- Application Frame:** The data is mapped into an application frame. This can be a "Partially filled application frame" or pass through an "Optional TimeSlot Interchange" block. +- Interface (I):** The "Partially filled application frame" is transmitted across the interface. +- Mapping and Maintenance (M):** The frame is processed through "Application frame" and "Core frame" blocks. +- Common Circuitry (C):** The "Core frame" is then mapped into HDSL frames. This stage is split into two parallel paths: + - (Three-pair):** The "Core frame" is mapped into HDSL frames for a three-pair system. + - (Two-pair):** The "Core frame" is mapped into HDSL frames for a two-pair system. +- HDSL Transceivers (H):** The HDSL frames are then transmitted to the HDSL transceivers. + +**Labels and Identifiers:** + +- Optional Functions (Outside the scope of this TS) +- Interface (I) +- Mapping and Maintenance (M) +- Common Circuitry (C) +- HDSL Transceivers (H) +- (Three-pair) +- (Two-pair) +- T1529530-98 + +Figure I.3/G.991.1 – Mapping process for fractional installation. The diagram shows the flow of data from an external interface through various processing blocks to HDSL transceivers. The process starts with an (n x 64) kbit/s data interface leading to an 'Application frame' block. This can be a 'Partially filled application frame' or pass through an 'Optional TimeSlot Interchange' block. It then enters the 'Interface (I)' section as a 'Partially filled application frame'. Next is the 'Mapping and Maintenance (M)' section, which contains 'Application frame' and 'Core frame' blocks. The data then enters the 'Common Circuitry (C)' section, which has two parallel paths: one for a '(Three-pair)' system and another for a '(Two-pair)' system. Both paths contain 'Core frame' and 'HDSL frames' blocks. Finally, the data is sent to 'HDSL Transceivers (H)' represented by boxes with an 'H' and signal lines. + +Figure I.3/G.991.1 – Mapping process for fractional installation + +![Two diagrams, (a) and (b), illustrating the mapping of time slots into a 2048 kbit/s application frame. Diagram (a) shows a frame with 32 time slots. TS0 is the first slot, TS1 to TSn are the next n slots, and TS(n+1) is the slot after. The remaining slots are filled with all-ones (AIS) data. Diagram (b) shows a similar frame but with a different number of time slots, TS16, and the remaining slots are also filled with all-ones (AIS) data.](a76fd8608a1490167e6c1a4ed32b38e6_img.jpg) + +Two diagrams, (a) and (b), illustrating the mapping of time slots into a 2048 kbit/s application frame. Diagram (a) shows a frame with 32 time slots. TS0 is the first slot, TS1 to TSn are the next n slots, and TS(n+1) is the slot after. The remaining slots are filled with all-ones (AIS) data. Diagram (b) shows a similar frame but with a different number of time slots, TS16, and the remaining slots are also filled with all-ones (AIS) data. + +T1529540-98 + +NOTE – Time slots of the 2048 kbit/s application frame are filled as follows: + +TS0 is filled according to ETS 300 167 [B15] + +TS16 is reserved for the accommodation, if required, of a 64 kbit/s signalling channel + +- if $2 \leq n \leq 15$ , TS1 to TSn are filled with $n \times 64$ kbit/s data a) +- if $15 < n \leq 30$ , TS1 to TS15 and TS17 to TS(n + 1) are filled with $n \times 64$ kbit/s data b) +- Remaining time slots are filled with all-ONEs (AIS) data. + +**Figure I.4/G.991.1 – Illustration of the fractional installation mapping into 2048 kbit/s application frame** + +**I.4.1.2 Details of mapping of the application interface from the HDSL core frame** + +The mapping process for 784 kbit/s transceiver is shown in Figures I.5 and I.6, and for 1168 kbit/s transceivers in Figure I.7. The application interface frame described in ETS 300 167 [20] is synchronously mapped bytewise into the core frame, with the application frame occupying a defined position within the HDSL frame. Unused bytes have an AIS signal (all-ONEs) inserted. + +![](28e47e64ac18ca4d8924dab65cedc2d8_img.jpg) + +| Core frame
Figure 6 c) | 2048 kbit/s
data at the
application frame
interface | | Core frame
filled with
2048 kbit/s data | | HDSL
pair 1 | HDSL
pair 2 | +|---------------------------|--------------------------------------------------------------|--------------------------|-----------------------------------------------|--------------------------|----------------|----------------| +| TS0 | | | TS0 | | | | +| | TS0 | | TS0 | | TS0 | TS0 | +| | UD1 in TS1 | | TS0 | | | | +| | UD2 in TS2 | | UD1 | | UD1 | UD2 | +| | AIS in TS3 | | UD2 | | | | +| | UD3 in TS4 | | AIS | | UD3 | UD4 | +| | UD4 in TS5 | | UD3 | | | | +| | AIS in TS6 | | UD4 | | UD5 | UD6 | +| | UD5 in TS7 | | AIS | | | | +| | UD6 in TS8 | | UD5 | | UD7 | UD8 | +| | AIS in TS9 | | UD6 | | | | +| | UD7 in TS10 | | AIS | | UD9 | UD10 | +| | UD8 in TS11 | | UD7 | | | | +| | AIS in TS12 | | UD8 | | TS1 | TS1 | +| | UD9 in TS13 | | AIS | | | | +| | UD10 in TS14 | | UD9 | | UD11 | UD12 | +| | AIS in TS15 | | UD10 | | | | +| | TS16 | core
frame
mapping | AIS | three
pair
mapping | UD13 | UD14 | +| | UD11 in TS17 | | TS16 | | | | +| | UD12 in TS18 | | TS16 | | UD15 | UD16 | +| | AIS in TS19 | | TS16 | | | | +| | UD13 in TS20 | | UD11 | | UD17 | UD18 | +| | UD14 in TS21 | | UD12 | | | | +| | AIS in TS22 | | AIS | | UD19 | UD20 | +| | UD15 in TS23 | | UD13 | | | | +| | UD16 in TS24 | | UD14 | | | | +| | AIS in TS25 | | AIS | | | | +| | UD17 in TS26 | | UD15 | | | | +| | UD18 in TS27 | | UD16 | | | | +| | AIS in TS28 | | AIS | | | | +| | UD19 in TS29 | | UD17 | | | | +| | UD20 in TS30 | | UD18 | | | | +| | AIS in TS31 | | AIS | | | | +| | | | UD19 | | | | +| | | | UD20 | | | | +| | | | AIS | | | | + +| | +|-----| +| AIS | +| UDn | + +All-ONEs data + +User data time slot n + +T1529550-98 + +**Figure I.5/G.991.1 – Mapping procedure for fractional installation of two out of three-pairs of a three-pair 784 kbit/s HDSL system** + +![](fc7c83167c4e9e614f40e52b39ef735d_img.jpg) + +| Core frame
Figure 6 c) | 2048 kbit/s
data at the
application frame
interface | | Core frame
filled with
2048 kbit/s data | | | HDSL
pair 1 | +|---------------------------|--------------------------------------------------------------|--------------------------|-----------------------------------------------|----|--------------------------|----------------| +| TS0 | | | TS0 | 0 | | TS0 | +| | | | TS0 | 1 | | | +| | TS0 | | TS0 | 2 | | | +| | UD1 in TS1 | | UD1 | 3 | | UD1 | +| | AIS in TS2 | | AIS | 4 | | | +| | AIS in TS3 | | AIS | 5 | | | +| | UD2 in TS4 | | UD2 | 6 | | UD2 | +| | AIS in TS5 | | AIS | 7 | | | +| | AIS in TS6 | | AIS | 8 | | | +| | UD3 in TS7 | | UD3 | 9 | | UD3 | +| | AIS in TS8 | | AIS | 10 | | | +| | AIS in TS9 | | AIS | 11 | | | +| | UD4 in TS10 | | UD4 | 12 | | UD4 | +| | AIS in TS11 | | AIS | 13 | | | +| | AIS in TS12 | | AIS | 14 | | | +| | UD5 in TS13 | | UD5 | 15 | | UD5 | +| | AIS in TS14 | | AIS | 16 | | | +| | AIS in TS15 | core
frame
mapping | AIS | 17 | three
pair
mapping | | +| | TS16 | | TS16 | 18 | | TS1 | +| | UD6 in TS17 | | TS16 | 19 | | | +| | AIS in TS18 | | TS16 | 20 | | | +| | AIS in TS19 | | UD6 | 21 | | UD6 | +| | UD7 in TS20 | | AIS | 22 | | | +| | AIS in TS21 | | AIS | 23 | | | +| | AIS in TS22 | | UD7 | 24 | | UD7 | +| | UD8 in TS23 | | AIS | 25 | | | +| | AIS in TS24 | | AIS | 26 | | | +| | AIS in TS25 | | UD8 | 27 | | UD8 | +| | UD9 in TS26 | | AIS | 28 | | | +| | AIS in TS27 | | AIS | 29 | | | +| | AIS in TS28 | | UD9 | 30 | | UD9 | +| | UD10 in TS29 | | AIS | 31 | | | +| | AIS in TS30 | | AIS | 32 | | | +| | AIS in TS31 | | UD10 | 33 | | UD10 | +| | | | AIS | 34 | | | +| | | | AIS | 35 | | | + +| | +|-----| +| AIS | +| UDn | + +All-ONEs data + User data time slot n + +T1529560-98 + +**Figure I.6/G.991.1 – Mapping procedure for fractional installation of one out of three-pairs of a three-pair 784 kbit/s HDSL system** + +![](b8dd9521b601d25e46c5effa0a59b7e1_img.jpg) + +| | | | | | | | +|---------------------------|--------------------------------------------------------|--------------------------|-----------------------------------------------|-----|-------------------------|----------------| +| Core frame
Figure 6 c) | 2048 kbit/s
data at the
application
interface | core
frame
mapping | Core frame
filled with
2048 kbit/s data | | two-
pair
mapping | HDSL
pair 1 | +| | | | TS0 | 0 | | | +| TS0 | TS0 | | 1 | TS0 | | | +| | TS0 | | UD1 | 2 | | UD1 | +| | UD1 in TS1 | | AIS | 3 | | | +| | AIS in TS2 | | UD2 | 4 | | UD2 | +| | UD2 in TS3 | | AIS | 5 | | | +| | AIS in TS4 | | UD3 | 6 | | UD3 | +| | UD3 in TS5 | | AIS | 7 | | | +| | AIS in TS6 | | UD4 | 8 | | UD4 | +| | UD4 in TS7 | | AIS | 9 | | | +| | AIS in TS8 | | UD5 | 10 | | UD5 | +| | UD5 in TS9 | | AIS | 11 | | | +| | AIS in TS10 | | UD6 | 12 | | UD6 | +| | UD6 in TS11 | | AIS | 13 | | | +| | AIS in TS12 | | UD7 | 14 | | UD7 | +| | UD7 in TS13 | | AIS | 15 | | | +| | AIS in TS14 | | UD8 | 16 | | UD8 | +| | UD8 in TS15 | | TS16 | 17 | | | +| | TS16 | | TS16 | 18 | | TS16 | +| | AIS in TS17 | | AIS | 19 | | | +| | UD9 in TS18 | | UD9 | 20 | | UD9 | +| | AIS in TS19 | | AIS | 21 | | | +| | UD10 in TS20 | | UD10 | 22 | | UD10 | +| | AIS in TS21 | | AIS | 23 | | | +| | UD11 in TS22 | | UD11 | 24 | | UD11 | +| | AIS in TS23 | | AIS | 25 | | | +| | UD12 in TS24 | | UD12 | 26 | | UD12 | +| | AIS in TS25 | | AIS | 27 | | | +| | UD13 in TS26 | | UD13 | 28 | | UD13 | +| | AIS in TS27 | | AIS | 29 | | | +| | UD14 in TS28 | | UD14 | 30 | | UD14 | +| | AIS in TS29 | | AIS | 31 | | | +| | UD15 in TS30 | | UD15 | 32 | | UD15 | +| | AIS in TS31 | | AIS | 33 | | | +| | | | AIS | 34 | | | +| | | AIS | 35 | AIS | | | + +| | | +|-----|-----------------------| +| AIS | All-ONEs data | +| UDn | User data time slot n | + +T1529570-98 + +**Figure I.7/G.991.1 – Fractional installation mapping onto one-pair of a two-pair system** + +#### I.4.1.3 Details of HDSL core frame mapping into HDSL frame + +The mapping from core frame to HDSL transmission frame takes place in exactly the same way as for the other applications, as can be seen from Figures I.5, I.6 and I.7. The pre-processing involved in mapping the application into the core frame is responsible for defining the final mapping onto the + +HDSL pairs. No additional processing is required in the core-to-HDSL mapping. The pairs carrying only AIS signal do not need to be equipped, the AIS being reinserted at the receiver. The CRC-4 checking in the application frame thus appears transparent through the system, i.e. from the point of view of the CRC-4 checking, the system behaves as if there were error free transmission on those channels (containing AIS) which were terminated at the transmitter and reintroduced at the receiver. + +#### I.4.1.4 Optional external mappings into the application frame + +Additional mappings from external data interfaces into the application frame may be implemented externally in order to facilitate applications such as point-to-multipoint operation, multiple ( $n \times 64$ ) kbit/s data streams, creation of high and low priority data streams (in the case of partial operation) and the mapping of contiguous blocks of time slots onto a specific HDSL pair. The definition of such mappings is, however, outside the scope of this Recommendation. + +#### I.4.2 Mapping of HDSL maintenance functions to the interface + +A fractionally installed system shall be considered fully operational when all the installed transceiver pairs have indicated completion of the activation procedure as described in 5.6 or B.5.6, correct pair identification has been achieved in the core frame, as described in 6.2 or B.5.6.9, and no further failure condition is detected. If one of the installed transceiver pairs is indicating non-operational condition or incorrect pair identification, the fractionally installed system shall be considered non-operational. + +The mapping of LOS/LFA at the line side of LTU, NTU and both sides of the REG to the application interface is shown in Table I.13, and Table I.14 shows how a complete and transparent loopback is achieved. + +**Table I.13/G.991.1 – Mapping of maintenance functions to the application interface** + +| Condition on one (or more) pair(s) | Message towards the application interface of | | +|------------------------------------|----------------------------------------------|--------| +| | NTU | LTU | +| LOS/LFA at LTU line side | Note 1 | Note 2 | +| LOS/LFA at NTU line side | Note 1 | Note 2 | +| LOS/LFA at REG-R | Note 1 | Note 2 | +| LOS/LFA at REG-C | Note 1 | Note 2 | + +NOTE 1 – As long as the selected transceiver(s) is not in the full operating state, the signal towards the application interface of the NTU is not defined. + +NOTE 2 – The message sent towards the application interface of the LTU shall either be AIS or AUXP dependent on the requirements of the network operator. + +**Table I.14/G.991.1 – Loopback in LTU** + +| Function | Localization | Controlled by | Requested via | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------|------------------------------|----------------------------------| +| Loopback 1 | As close as possible to the line | OAM in block M in LTU (Note) | The application interface of LTU | +| NOTE – When the loopback 1 is requested via the application interface of the LTU a complete and transparent loopback shall be activated in all HDSL transceivers on the line side of the LTU. These loopbacks are managed by an OAM function inside the functional block M in LTU. | | | | + +### **I.4.3 Performance** + +#### **I.4.3.1 Performance specification** + +The overall performance must be such that the performance limits given in Recommendation G.826 [B9] can be met. For the purpose of conformance, an HDSL transmission system is required to meet the specific laboratory performance tests that are defined in the following subclauses. + +The performance requirements have been specified so that the HDSL transceivers are tolerant to near-end crosstalk (NEXT), impulsive noise and shaped noise, and not optimized for only one operating condition. + +The one way signal transfer delay shall be as defined in I.1.3.2. + +#### **I.4.3.2 Clock specification for external interfaces** + +##### **I.4.3.2.1 Clock tolerance** + +The clock tolerance shall be as defined in I.1.3.3.1 and I.1.3.3.2. + +##### **I.4.3.2.2 Jitter and wander specifications** + +The jitter specifications of I.1.3.3 shall be applied to the application interface. The specification of jitter and wander at the output of the external data interface is outside the scope of this Recommendation. + +#### **I.4.3.3 Laboratory performance measurements** + +It is assumed that performance can be evaluated at the application interface, avoiding the need for test access to the individual data channels. The test arrangement and procedures of 6.3 or B.6.2 shall be used. + +### **I.5 Application specific requirements for partial operation** + +#### **I.5.1 Mapping of the application frame for partial operation application** + +As described in 5.4 (frame structure) the 2048 kbit/s application data is mapped into a core frame with 144 bytes and 500 µs length. If the mapping option in Figure 6 c) is implemented, then the possibility exists for partial operation of the system in the case of failure of transmission on one or more of the pairs. This mapping is shown in more detail for the case of partial operation in Figure I.8 (three-pair system) and Figure I.9 (two-pair system). These mappings allow ISDN PRA or ETS 300 167 [B15] framed operation in normal operation, but permit reduced capacity operation if one or two-pairs fail. It is also possible to have partial operation in the case of partial failure of a fractionally installed three-pair system. + +In the case of partial operation, the output mapping for the non-corrupted channels shall be unchanged, and missing channel time slots shall be filled with all-ONEs data (AIS). In addition, the necessary modification of the embedded maintenance functions (TS0 and TS16) shall be carried out in accordance with I.5.2. + +![](defe20e5056d0c3552de2d50ce88c5cb_img.jpg) + +| Core frame
Figure 6 c) | 2048 kbit/s
data at the
application frame
interface | Core frame
filled with
2048 kbit/s data | | HDSL
pair 1 | HDSL
pair 2 | HDSL
pair 3 | +|---------------------------|--------------------------------------------------------------|-----------------------------------------------|----|----------------|----------------|----------------| +| TS0 | | TS0 | 0 | | | | +| | | TS0 | 1 | TS0 | TS0 | TS0 | +| | TS0 | TS0 | 2 | | | | +| | TS1 | TS1 | 3 | TS1 | TS2 | TS3 | +| | TS2 | TS2 | 4 | | | | +| | TS3 | TS3 | 5 | TS4 | TS5 | TS6 | +| | TS4 | TS4 | 6 | | | | +| | TS5 | TS5 | 7 | TS7 | TS8 | TS9 | +| | TS6 | TS6 | 8 | | | | +| | TS7 | TS7 | 9 | TS10 | TS11 | TS12 | +| | TS8 | TS8 | 10 | | | | +| | TS9 | TS9 | 11 | TS13 | TS14 | TS15 | +| | TS10 | TS10 | 12 | | | | +| | TS11 | TS11 | 13 | TS1 | TS1 | TS1 | +| | TS12 | TS12 | 14 | | | | +| | TS13 | TS13 | 15 | TS17 | TS18 | TS19 | +| | TS14 | TS14 | 16 | | | | +| | TS15 | TS15 | 17 | TS20 | TS21 | TS22 | +| | TS16 | TS16 | 18 | | | | +| | | TS16 | 19 | TS23 | TS24 | TS25 | +| | TS17 | TS16 | 20 | | | | +| | TS18 | TS17 | 21 | TS26 | TS27 | TS28 | +| | TS19 | TS18 | 22 | | | | +| | TS20 | TS19 | 23 | TS29 | TS30 | TS31 | +| | TS21 | TS20 | 24 | | | | +| | TS22 | TS21 | 25 | | | | +| | TS23 | TS22 | 26 | | | | +| | TS24 | TS23 | 27 | | | | +| | TS25 | TS24 | 28 | | | | +| | TS26 | TS25 | 29 | | | | +| | TS27 | TS26 | 30 | | | | +| | TS28 | TS27 | 31 | | | | +| | TS29 | TS28 | 32 | | | | +| | TS30 | TS29 | 33 | | | | +| | TS31 | TS30 | 34 | | | | +| | | TS31 | 35 | | | | + +core +frame +mapping + +three +pair +mapping + +█ User data (30 × 64 kbit/s channels) + +T1529580-98 + +**Figure I.8/G.991.1 – Core frame mapping – Synchronous mapping onto three-pairs** + +![](af4f213abb5ad1891a43425e0d758021_img.jpg) + +| Core frame
Figure 6 c) | 2048 kbit/s
data at the
application frame
interface | Core frame
filled with
2048 kbit/s data | | HDSL
pair 1 | HDSL
pair 2 | +|---------------------------|--------------------------------------------------------------|-----------------------------------------------|----|----------------|----------------| +| TS0 | | TS0 | 0 | TS0 | TS0 | +| | TS0 | TS0 | 1 | | | +| | TS1 | TS1 | 2 | TS1 | TS2 | +| | TS2 | TS2 | 3 | | | +| | TS3 | TS3 | 4 | TS3 | TS4 | +| | TS4 | TS4 | 5 | | | +| | TS5 | TS5 | 6 | TS5 | TS6 | +| | TS6 | TS6 | 7 | | | +| | TS7 | TS7 | 8 | TS7 | TS8 | +| | TS8 | TS8 | 9 | | | +| | TS9 | TS9 | 10 | TS9 | TS10 | +| | TS10 | TS10 | 11 | | | +| | TS11 | TS11 | 12 | TS11 | TS12 | +| | TS12 | TS12 | 13 | | | +| | TS13 | TS13 | 14 | TS13 | TS14 | +| | TS14 | TS14 | 15 | | | +| | TS15 | TS15 | 16 | TS15 | TS1 | +| | TS16 | TS16 | 17 | | | +| | | TS16 | 18 | TS16 | TS17 | +| | TS17 | TS17 | 19 | | | +| | TS18 | TS18 | 20 | TS18 | TS19 | +| | TS19 | TS19 | 21 | | | +| | TS20 | TS20 | 22 | TS20 | TS21 | +| | TS21 | TS21 | 23 | | | +| | TS22 | TS22 | 24 | TS22 | TS23 | +| | TS23 | TS23 | 25 | | | +| | TS24 | TS24 | 26 | TS24 | TS25 | +| | TS25 | TS25 | 27 | | | +| | TS26 | TS26 | 28 | TS26 | TS27 | +| | TS27 | TS27 | 29 | | | +| | TS28 | TS28 | 30 | TS28 | TS29 | +| | TS29 | TS29 | 31 | | | +| | TS30 | TS30 | 32 | TS30 | TS31 | +| | TS31 | TS31 | 33 | | | +| | | AIS | 34 | AIS | AIS | +| | | AIS | 35 | | | + +core +frame +mapping + +three +pair +mapping + +| | | +|-----|-------------------------------------| +| | User data (30 × 64 kbit/s channels) | +| AIS | All-ONEs signal | + +T1529590-98 + +**Figure I.9/G.991.1 – Core frame mapping – Synchronous mapping onto two-pairs** + +### I.5.2 Mapping of HDSL maintenance functions to the interface + +The HDSL embedded operations channel (eoc) is transmitted in parallel over all the HDSL pairs (5.5.2). Thus, in the event of a failure of one of the HDSL pairs, all the functions of the eoc will still be available on the remaining pairs. In the event of a pair failure, there will be some means of communicating the failure to the HDSL mapping function so that the mapping function may take the appropriate actions, such as time slot reallocation (if required) and insertion of AIS into the non-supportable time slots. The mapping and maintenance block shall continually monitor the status of all pairs and in particular, that of any failed pair(s). When a failure condition has been cleared, the M block may then reallocate the previously unsupportable time slots to the reactivated pair. + +The access digital section shall be considered operational, when all of the transceiver pairs have indicated completion of the activation procedure, correct pair identification has been achieved in the core frame, as described in 5.6, and no further failure condition is detected. If one of the transceiver pairs is indicating non-operational condition, or incorrect pair identification, the access digital section shall be considered non-operational. When during operation a transceiver becomes inoperable, the transport in the other loops is still operating. The mapping of LOS/LFA at the line side of LTU, NTU and both sides of the REG to the application interface is shown in Table I.15, and Table I.16 shows how a complete transparent loopback is achieved. + +**Table I.15/G.991.1 – Mapping of maintenance functions to the application interface** + +| Condition on one (or more) pair(s) | Message towards the application interface of | | +|---------------------------------------------------------|----------------------------------------------|------| +| | NTU | LTU | +| LOS/LFA at LTU line side | Note | Note | +| LOS/LFA at NTU line side | Note | Note | +| LOS/LFA at REG-R | Note | Note | +| LOS/LFA at REG-C | Note | Note | +| NOTE – AIS in the time slots of the inoperable loop(s). | | | + +**Table I.16/G.991.1 – Loopback in the LTU** + +| Function | Localization | Controlled by | Requested via | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------|------------------------------|----------------------------------| +| Loopback 1 | As close as possible to the line | OAM in block M in LTU (Note) | The application interface of LTU | +| NOTE – When the loopback 1 is requested via the application interface of the LTU, a complete and transparent loopback shall be activated in all HDSL transceivers on the line side of the LTU. These loopbacks are managed by an OAM function inside the functional block M in LTU. | | | | + +### I.5.3 Performance + +The overall performance must be such that the performance limits given in Recommendation G.826 [B9] can be met, for either the complete transmission system, or the individual data channels supported during partial operation. + +The performance specification for the ISDN PRA application as described in I.1.3 shall be applied. It is not necessary to test the performance for partial operation separately. + +The partial operation functionality shall be tested by interrupting each loop in turn, and confirming that the system continues to operate correctly in the partial operation mode, and that the performance of the remaining channels is acceptable. + +#### **I.5.4 Remote power feeding** + +It should be noted that in HDSL systems which rely solely on remote power feeding the NTU may not work in the event of a pair failure due to the fact that the NTU may consume more power than can be supplied over a single pair, especially where loops with high DC resistances are involved. For such systems, locally powered NTUs may be appropriate. + +#### **I.5.5 Partial failure criteria** + +The criteria for detection of partial failure should not be based solely on LOSW (loss of sync word) because this could be generated by a trivial event (e.g. noise event ) and should not be interpreted as a line failure. + +Activation flags should be used to indicate pair(s) failure (e.g. LOS, LOST) to the mapping and maintenance functional block. + +#### **I.5.6 Action following partial failure** + +The transceiver which has flagged a failure to the mapping and maintenance functional block shall automatically initiate start-up procedures independently of the other transceivers in the system and continue to do so until it is able to reactivate the link. Once this has been achieved, the pair failure flag should be cleared. The mapping and maintenance function may then reallocate this additional capacity to the transmission of application data. + +#### **I.5.7 Time slot prioritization/reallocation** + +In some applications, there may be a need to assign priorities to time slots so that, if any of the pairs fail, the time slots with the highest priority only are transmitted on the remaining pair(s). This implies that, in the event of a pair failure, dynamic reallocation of the high priority time slots to the remaining pairs is required, along with a means of agreeing the reallocation details between the LTU and the NTU. Since the LTU is the master as far as OAM functions are concerned, the time slot reallocation strategy is to be determined at the LTU end of the system. The reallocation may be performed at various points in the transmission path, for example: + +- a) time slot interchanger at the application interface; +- b) core frame mapping; +- c) pair mapping. + +Option a) assumes that the application interfaces at both the LTU and the NTU contain the functionality required to interchange time slots and to deal appropriately with signalling and error correction bits in the application frame, so that the application frame can be reconstructed at both application interfaces. This option allows the core and frame mapping at the LTU and the NTU to stay the same following a pair failure. + +NOTE – High Priority TSs will be in the new application frames, and Low Priority TSs will not and contain instead AIS. + +UNI and NNI non-HDSL equipment would need to know status of pairs, because they could not otherwise distinguish between pair failure and no call info which both are indicated by AIS. + +Option b) requires a mechanism for informing the NTU core frame mapping function of the changes to the LTU core frame mapping, so that the NTU can replicate the changes. + +Option c) requires a mechanism for informing the NTU HDSL frame mapping function of the changes to the LTU HDSL frame mapping, so that the NTU can replicate the changes. + +## I.6 Application specific requirements for the 2048 kbit/s mapped into TU-12 structure + +### I.6.1 Reference Configuration + +The amended access section for the HDSL transmission system with TU-12 structured signals is shown in Figure I.10. At the NTU mapping part additional VC-12 and TU-12 functions are inserted. The LTU is part of a SDH equipment. + +![Figure I.10/G.991.1 – Access Section for TU-12 transport employing HDSL technology. The diagram shows the flow of data from an application interface on the customer side, through mapping (VC-12, TU-12, Core), common circuitry, and an HDSL transceiver to an NTU. The NTU connects via Digital Local Lines (DLLs) to an LTU (part of SDH equipment). The LTU connects to another HDSL transceiver, common circuitry, and mapping (Core, Maintenance, TU-12) which then connects to the SDH Core. The HDSL core is transparent to the core frame payload. The diagram also shows maintenance channels, reference points, and functional blocks.](e29db6b12743ccb6dc6c48860eb8b4fb_img.jpg) + +The diagram illustrates the reference configuration for TU-12 transport over HDSL. It is divided into two main sections: the Customer side and the Network side equipment, connected by Digital Local Lines (DLLs). + +- Customer side:** Starts with an **Application interface** leading to a **Mapping** block. The **Mapping** block contains **VC-12**, **TU-12**, and **Core** sub-blocks, with a **Maintenance** sub-block below the **Core**. This is followed by **Common circuitry** and an **HDSL transceiver**. The **HDSL transceiver** is connected to an **NTU**. The **NTU** is connected to the **Digital Local Lines (DLLs)**. The **Digital Local Lines (DLLs)** are connected to the **LTU** (part of **SDH-Core**). +- Network side equipment:** The **LTU** is connected to an **HDSL transceiver**, which is connected to **Common circuitry**. The **Common circuitry** is connected to a **Mapping** block. The **Mapping** block contains **Core**, **Maintenance**, and **TU-12** sub-blocks. The **TU-12** sub-block is connected to the **SDH-Core**. The **SDH-Core** is connected to the **VC-12 reference point**. +- Access digital section:** This section is shown at the top, spanning from the **Application interface** to the **SDH-Core**. It is labeled **HDSL core transparent to core frame payload**. +- Maintenance:** Maintenance channels are shown throughout the diagram, with reference points at the **Mapping** blocks on both sides. +- Clock and synchronization information:** This is shown as a separate line connecting the **Mapping** block on the customer side to the **Common circuitry** on the network side. +- Legend:** + - Bidirectional transmission + - Functional Block +- NOTE:** A fully equipped HDSL core consists of one, two or three H, REG, DLL combinations depending on HDSL transceiver data transmission rate. REGs are optional. +- Reference:** T1529600-98 + +Figure I.10/G.991.1 – Access Section for TU-12 transport employing HDSL technology. The diagram shows the flow of data from an application interface on the customer side, through mapping (VC-12, TU-12, Core), common circuitry, and an HDSL transceiver to an NTU. The NTU connects via Digital Local Lines (DLLs) to an LTU (part of SDH equipment). The LTU connects to another HDSL transceiver, common circuitry, and mapping (Core, Maintenance, TU-12) which then connects to the SDH Core. The HDSL core is transparent to the core frame payload. The diagram also shows maintenance channels, reference points, and functional blocks. + +Figure I.10/G.991.1 – Access Section for TU-12 transport employing HDSL technology + +## I.6.2 Application Interfaces + +### I.6.2.1 Application interface at the customer side + +The application interface at the customer side shall be a 2048 kbit/s digital unstructured leased line interface according to ETS 300 418 [B6] and ETS 300 247 [B5]. + +### I.6.2.2 Application interface at the network side + +No application interface exists at the network side, only a VC-12 reference point internal to the network side equipment between the LTU and the SDH core is defined. + +## I.6.3 Mapping of application frame into HDSL using TU-12 structure + +The data at the application frame are mapped to HDSL in three steps. + +### **I.6.3.1 Mapping of application frame into VC-12 structure** + +The data at the application interface are mapped into VC-12 structure according to 10.1.4/G.707 [B14]. All mapping modes as described in this Recommendation shall be supported. + +### **I.6.3.2 Mapping of VC-12 into TU-12** + +The VC-12 are mapped into the TU-12 structure according to 8.3/G.707 [B14]. + +### **I.6.3.3 Mapping of TU-12 into HDSL** + +As described in 5.4 the TU-12 structured data having a bit rate of 2304 kbit/s shall be mapped into a core frame with 144 bytes and 500 $\mu$ s length. Pointer byte V1 shall be located in byte 144 of the core frame. The bits $Z_{m9}$ to $Z_{m48}$ are unused and shall be set to ONE. + +The mapping process into three and two-pairs is shown in Figures I.11 and I.12. + +![](eca6a6c6546af8ac124c207445901964_img.jpg) + +| Core frame according to Figure 6 c) | Core frame filled with TU-12 data | HDSL pair 1 | HDSL pair 2 | HDSL pair 3 | +|-------------------------------------|-----------------------------------|-------------|-------------|-------------| +| Byte 1 | 105 | 105 | 106 | 107 | +| Byte 2 | X | X | X | X | +| Byte 35 | | | | | +| Byte 36 | 139 | 138 | 139 | V2 | +| Byte 37 | V2 | 0 | 1 | 2 | +| X | 0 | X | X | X | +| | Byte 70 | | | | +| Byte 71 | 34 | 33 | 34 | V3 | +| Byte 72 | V3 | 35 | 36 | 37 | +| X | 35 | X | X | X | +| | Byte 109 | | | | +| Byte 107 | 69 | 68 | 69 | V4 | +| Byte 108 | V4 | 70 | 71 | 72 | +| X | 70 | X | X | X | +| | Byte 144 | | | | +| | 104 | 103 | 104 | V1 | +| | V1 | | | | + +core frame mapping      three pair mapping + +T1529610-98 + +NOTE – V1, V2 and V3 are TU-12 pointers 1, 2 and 3; V4 is set to ONE. These bytes are part of the TU-12 and terminated at a pointer processor. + +**Figure I.11/G.991.1 – Core frame mapping of TU-12 option – Synchronous mapping into three-pairs** + +![](1ab8da167ae10f58b4b0b57e0c1283ad_img.jpg) + +| Core frame according to Figure 6 c) | Core frame filled with TU-12 data | | HDSL pair 1 | HDSL pair 2 | +|-------------------------------------|-----------------------------------|--------------------|-------------|-------------| +| Byte 1 | 105 | | | | +| Byte 2 | | | 105 | 106 | +| ⌂ | ⌂ | | ⌂ | ⌂ | +| Byte 35 | 139 | | 139 | V2 | +| Byte 36 | V2 | | | | +| Byte 37 | 0 | | 0 | 1 | +| ⌂ | ⌂ | | ⌂ | ⌂ | +| Byte 70 | 34 | core frame mapping | 34 | V3 | +| Byte 71 | V3 | | | | +| Byte 72 | 35 | | 35 | 36 | +| ⌂ | ⌂ | | ⌂ | ⌂ | +| Byte 109 | 69 | | 69 | V4 | +| Byte 107 | V4 | | | | +| Byte 108 | 70 | | 70 | 71 | +| ⌂ | ⌂ | | ⌂ | ⌂ | +| Byte 144 | 104 | | 104 | V1 | +| | V1 | | | | + +T1529620-98 + +NOTE – V1, V2 and V3 are TU-12 pointers 1, 2 and 3; V4 is set to ONE. These bytes are part of the TU-12 and terminated at a pointer processor. + +**Figure I.12/G.991.1 – Core frame mapping of TU-12 option – Synchronous mapping into two-pairs** + +#### I.6.4 Mapping of HDSL maintenance functions to the interface + +The access digital section shall be considered operational when all of the transceiver pairs have indicated completion of the activation procedure (see 5.6 or B.5.6), correct pair identification has been achieved in the core frame, as described in 6.2 or B.5.6.9, and no further failure condition is detected. If one of the transceiver pairs is indicating non-operational condition or incorrect pair identification, the access digital section shall be considered non-operational. + +The fact that the D2048U signal is unstructured makes it impossible for the HDSL core to map any operation and maintenance information into or out of the payload because the HDSL system does not have any information about the contents or the internal structure of the transmitted data. + +The only information the core can get is "LOS at the application interface of LTU" and "LOS at the application interface of NTU". When LOS at the application interface of NTU or LTU is detected, an "All ONEs" signal shall be transmitted to the far end of the HDSL system. At the same time bit 15 of the HDSL frame ("losd") shall be set to ZERO as shown in Table I.17. + +**Table I.17/G.991.1 – LOS at the application interface of LTU and NTU** + +| Leased line input condition | Action | +|-----------------------------------------|---------------------------| +| LOS at the application interface of LTU | losd = 0 in HOH (LTU/NTU) | +| LOS at the application interface of NTU | losd = 0 in HOH (NTU/LTU) | + +The mapping of LOS/LFA at the line side of LTU, NTU, and both sides of REG to the application interface is shown in Table I.18. + +**Table I.18/G.991.1 – Mapping of maintenance functions to the application interfaces** + +| Condition on one (or more) pair(s) | Message towards the application interface of | | +|------------------------------------|----------------------------------------------|-----| +| | NTU | LTU | +| LOS/LFA at LTU line side | Note | AIS | +| LOS/LFA at NTU line side | Note | AIS | +| LOS/LFA at REG-R | Note | AIS | +| LOS/LFA at REG-C | Note | AIS | + +NOTE – As long as the HDSL system is not in the full operating state, i.e. not all of the HDSL transceivers are in the Active-Rx/Tx state, the signal towards the application interface of the NTU is not defined. + +#### I.6.5 Performance + +##### I.6.5.1 Performance specification + +The overall performance shall be such that the performance limits defined in Recommendation G.826 [B9] can be met. + +### I.6.5.2 Signal transfer delay + +The one-way signal transfer delay between the application interface at the NTU and the TU-12 reference point at the LTU shall not exceed 1250 $\mu\text{s}$ . This shall be calculated as the mean delay for both directions. The allocation for a 2B1Q HDSL system shall be as follows: + +| | | +|------|------------------------| +| LTU | $\leq 450 \mu\text{s}$ | +| NTU | $\leq 450 \mu\text{s}$ | +| REG | $\leq 200 \mu\text{s}$ | +| Line | $\leq 150 \mu\text{s}$ | + +### I.6.5.3 Clock specification + +#### I.6.5.3.1 Clock synchronization at the NTU + +The TU-12 signal towards the network shall use the TU-12 timing of the incoming direction from the network side as timing reference. + +The NTU timing towards the application interface may be derived from: + +- the received VC-12 signal; +- the received TU-12 signal, with an additional frame buffer inserted in the receive direction. + +#### I.6.5.3.2 Jitter specification + +The tolerance to input jitter as well as the jitter transfer limitation are defined in terms of the amplitude and frequency of sinusoidal input jitter which, when modulating a $2^{15}-1$ pseudo random test sequence of the 2048 kbit/s bit stream at the nominal rate and with tolerances of +50 ppm and -50 ppm, shall not cause bit errors in the transmission system or jitter at the relevant output in excess of the limits defined below. This test method is used for convenience of testing and is not, in itself, intended to be representative of the type of jitter to be found in practice. + +The tolerable input jitter is given in Figure I.1 (see I.1.3.3.3) with the values of Table I.19. The output jitter limits given in Table I.20 shall be met when applying the tolerable jitter to the relevant input. + +**Table I.19/G.991.1 – Parameter values for input jitter tolerance at inputs** + +| Application Interface | Parameter | Peak-to-peak amplitude | | | Frequency | | | | | +|-----------------------|-----------|------------------------|------------------|------------------|-----------|----|------|------|-----| +| | | A0 | A1 | A2 | f0 | f1 | f2 | f3 | f4 | +| At NTU (input) | Value | – | 1.1 | 0.11 | – | – | 4 | 0.04 | 100 | +| At LTU (input) | Value | – | 1.35 | 0.18 | – | 20 | 2400 | 18 | 100 | +| | Units | – | UI pp | UI pp | – | Hz | Hz | kHz | kHz | + +NOTE 1 – UIpp = Unit Interval peak-peak. $1 \text{ UI}_{\text{pp}} = \frac{1}{2048} \text{ kHz} = 488 \text{ ns}$ for the D2048U application. +NOTE 2 – The values for the NTU input are taken from ETS 300 247 [B5]. +NOTE 3 – The values for the LTU input are taken from Recommendation G.823 but reduced by 10% margin for jitter accumulation in the HDSL transmission system. + +**Table I.20/G.991.1 – Maximum permitted values of output jitter** + +| Application Interface | | Maximum permissible jitter | | Measurement bandpass parameters
(high pass part has first order slope) | | | +|-----------------------|-------|----------------------------|------------------|---------------------------------------------------------------------------|--------|-----| +| | | Parameter | B1; (f1-f4) | B2; (f3-f4) | f1 | f3 | +| At NTU output | Value | 1.5 | 0.2 | 20 | 18 000 | 100 | +| At LTU output | Value | 0.3 | 0.15 | 20 | 700 | 100 | +| | Units | UI pp | UI pp | Hz | Hz | kHz | + +NOTE 1 – The values for the NTU output are taken from ETS 300 247 [B5]. + +NOTE 2 – The values for the LTU output are based on the input at NTU, but increased for jitter accumulation in the HDSL transmission system in the lower frequency area and based on high Q transmission network following. + +#### I.6.5.4 Laboratory performance measurement + +The test arrangement and procedures of 6.3 or B.6.2 shall be used. The performance shall be evaluated between the application interface at the NTU and the VC-12 reference point in the LTU between the mapping functionality and the SDH core. A special adaptor will be used for the connection of the measuring equipment to the internal VC-12 reference point. + +### APPENDIX II + +#### Detailed definition of cable characteristics and test loops + +#### II.1 Typical characteristics of cables + +This appendix contains tables of typical parameters of cables, together with calculated values of the expected test loop behaviour. Practical measurements on cables or test loops will not necessarily be identical to the values in these tables. Additional information on cables and test loops (including graphical representations) can be found in Annex C/G.960 [2] + +**Table II.1/G.991.1 – Parameters of 0.4 mm PE cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|------------|------|--------|--------|--------|---------|---------|---------|---------|---------| +| R' (Ω/km) | 268 | 268 | 269 | 271 | 282 | 295 | 312 | 390 | 425 | +| L' (μH/km) | 680 | 678 | 675 | 669 | 650 | 642 | 635 | 619 | 608 | +| C' (nF/km) | 45.5 | 45.5 | 45.5 | 45.5 | 45.5 | 45.5 | 45.5 | 45.5 | 45.5 | + +**Table II.2/G.991.1 – Parameters of 0.5 mm PE cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|------------|------|--------|--------|--------|---------|---------|---------|---------|---------| +| R' (Ω/km) | 172 | 172 | 173 | 175 | 190 | 207 | 227 | 302 | 334 | +| L' (μH/km) | 680 | 678 | 675 | 667 | 646 | 637 | 629 | 603 | 592 | +| C' (nF/km) | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | + +**Table II.3/G.991.1 – Parameters of 0.6 mm PE cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|--------------------|-------------|---------------|---------------|---------------|----------------|----------------|----------------|----------------|----------------| +| R' ( $\Omega$ /km) | 119 | 120 | 121 | 125 | 146 | 167 | 189 | 260 | 288 | +| L' ( $\mu$ H/km) | 700 | 695 | 693 | 680 | 655 | 641 | 633 | 601 | 590 | +| C' (nF/km) | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | + +**Table II.4/G.991.1 – Parameters of 0.8 mm PE cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|--------------------|-------------|---------------|---------------|---------------|----------------|----------------|----------------|----------------|----------------| +| R' ( $\Omega$ /km) | 67 | 70 | 72.5 | 75.0 | 91.7 | 105 | 117 | 159 | 177.5 | +| L' ( $\mu$ H/km) | 700 | 700 | 687 | 665 | 628 | 609 | 595 | 568 | 543 | +| C' (nF/km) | 37.8 | 37.8 | 37.8 | 37.8 | 37.8 | 37.8 | 37.8 | 37.8 | 37.8 | + +**Table II.5/G.991.1 – Parameters of 0.32 mm PVC cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|--------------------|-------------|---------------|---------------|---------------|----------------|----------------|----------------|----------------|----------------| +| R' ( $\Omega$ /km) | 419 | 419 | 419 | 419 | 427 | 453 | 493 | 679 | 750 | +| L' ( $\mu$ H/km) | 650 | 650 | 650 | 650 | 647 | 635 | 621 | 577 | 560 | +| C' (nF/km) | 120 | 120 | 120 | 120 | 120 | 120 | 120 | 120 | 120 | + +**Table II.6/G.991.1 – Parameters of 0.4 mm PVC cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|--------------------|-------------|---------------|---------------|---------------|----------------|----------------|----------------|----------------|----------------| +| R' ( $\Omega$ /km) | 268 | 268 | 268 | 268 | 281 | 295 | 311 | 391 | 426 | +| L' ( $\mu$ H/km) | 650 | 650 | 650 | 650 | 635 | 627 | 619 | 592 | 579 | +| C' (nF/km) | 120 | 120 | 120 | 120 | 120 | 120 | 120 | 120 | 120 | + +**Table II.7/G.991.1 – Parameters of 0.63 mm PVC cables** + +| Frequency | 0 Hz | 10 kHz | 20 kHz | 40 kHz | 100 kHz | 150 kHz | 200 kHz | 400 kHz | 500 kHz | +|--------------------|-------------|---------------|---------------|---------------|----------------|----------------|----------------|----------------|----------------| +| R' ( $\Omega$ /km) | 108 | 108 | 108 | 111 | 141 | 173 | 207 | 319 | 361 | +| L' ( $\mu$ H/km) | 635 | 635 | 635 | 630 | 604 | 584 | 560 | 492 | 469 | +| C' (nF/km) | 120 | 120 | 120 | 120 | 120 | 120 | 120 | 120 | 120 | + +## II.2 Theoretical characteristics of test loops for Y = 31 dB at 150 kHz + +**Table II.8/G.991.1 – Loop 2** + +| Frequency (kHz) | | 10 | 20 | 40 | 100 | 150 | 200 | 400 | 500 | +|----------------------------------|-----|-----------|-----------|-----------|------------|------------|------------|------------|------------| +| Attenuation (dB) | | 15.2 | 19.0 | 23.4 | 28.6 | 31.0 | 33.3 | 42.5 | 46.8 | +| Phase (deg) | | -97 | -165 | -280 | -611 | -889 | -1168 | -2277 | -2823 | +| Group Delay ( $\mu\text{s}$ ) | | 21.7 | 17.0 | 15.4 | 15.4 | 15.5 | 15.6 | 15.3 | 15.1 | +| Impedance ( $\Omega$ )
at NTU | Re. | 228 | 179 | 146 | 126 | 122 | 120 | 117 | 117 | +| | Im. | -209 | -129 | -82 | -39 | -28 | -23 | -14 | -13 | +| Impedance ( $\Omega$ )
at LTU | Re. | 228 | 179 | 146 | 126 | 122 | 120 | 117 | 117 | +| | Im. | -209 | -129 | -82 | -39 | -28 | -23 | -14 | -13 | + +**Table II.9/G.991.1 – Loop 3** + +| Frequency (kHz) | | 10 | 20 | 40 | 100 | 150 | 200 | 400 | 500 | +|----------------------------------|-----|-----------|-----------|-----------|------------|------------|------------|------------|------------| +| Attenuation (dB) | | 16.4 | 20.0 | 23.2 | 28.3 | 31.3 | 34.5 | 45.9 | 50.3 | +| Phase (deg) | | -114 | -191 | -336 | -770 | -1129 | -1489 | -2896 | -3588 | +| Group Delay ( $\mu\text{s}$ ) | | 23.8 | 20.2 | 20.1 | 20.0 | 20.0 | 19.9 | 19.4 | 19.1 | +| Impedance ( $\Omega$ )
at NTU | Re. | 219 | 199 | 166 | 120 | 123 | 120 | 117 | 116 | +| | Im. | -152 | -98 | -91 | -41 | -27 | -26 | -13 | -13 | +| Impedance ( $\Omega$ )
at LTU | Re. | 257 | 190 | 134 | 128 | 121 | 116 | 118 | 120 | +| | Im. | -201 | -151 | -84 | -33 | -34 | -19 | -17 | -12 | + +**Table II.10/G.991.1 – Loop 4** + +| Frequency (kHz) | | 10 | 20 | 40 | 100 | 150 | 200 | 400 | 500 | +|----------------------------------|-----|-----------|-----------|-----------|------------|------------|------------|------------|------------| +| Attenuation (dB) | | 15.3 | 19.3 | 23.3 | 28.2 | 31.2 | 34.3 | 45.6 | 50.0 | +| Phase (deg) | | -113 | -195 | -339 | -768 | -1126 | -1484 | -2887 | -3578 | +| Group Delay ( $\mu\text{s}$ ) | | 25.5 | 20.9 | 19.6 | 19.9 | 20.0 | 19.9 | 19.3 | 19.1 | +| Impedance ( $\Omega$ )
at NTU | Re. | 128 | 110 | 114 | 105 | 109 | 108 | 103 | 103 | +| | Im. | -143 | -68 | -26 | -18 | -18 | -11 | -9 | -7 | +| Impedance ( $\Omega$ )
at LTU | Re. | 263 | 210 | 192 | 159 | 165 | 159 | 157 | 157 | +| | Im. | -205 | -122 | -75 | -30 | -34 | -16 | -13 | -12 | + +**Table II.11/G.991.1 – Loop 5** + +| Frequency (kHz) | | 10 | 20 | 40 | 100 | 150 | 200 | 400 | 500 | +|----------------------------------|-----|-----------|-----------|-----------|------------|------------|------------|------------|------------| +| Attenuation (dB) | | 13.9 | 16.7 | 18.6 | 24.4 | 28.9 | 33.0 | 46.1 | 51.1 | +| Phase (deg) | | –160 | –290 | –545 | –1300 | –1912 | –2512 | –4838 | –5963 | +| Group Delay ( $\mu\text{s}$ ) | | 36.5 | 35.5 | 35.4 | 34.4 | 33.6 | 33.5 | 31.3 | 30.7 | +| Impedance ( $\Omega$ )
at NTU | Re. | 164 | 144 | 126 | 87 | 67 | 57 | 60 | 79 | +| | Im. | –95 | –71 | –60 | –55 | –44 | –31 | +8 | +11 | +| Impedance ( $\Omega$ )
at LTU | Re. | 164 | 144 | 126 | 87 | 67 | 57 | 60 | 79 | +| | Im. | –95 | –71 | –60 | –55 | –44 | –31 | +8 | +11 | + +**Table II.12/G.991.1 – Loop 6** + +| Frequency (kHz) | | 10 | 20 | 40 | 100 | 150 | 200 | 400 | 500 | +|----------------------------------|-----|-----------|-----------|-----------|------------|------------|------------|------------|------------| +| Attenuation (dB) | | | 12.4 | 21.9 | 31.2 | 27.0 | 28.1 | 35.7 | 41.4 | +| Phase (deg) | | –81 | –138 | –232 | –413 | –612 | –833 | –1613 | –1977 | +| Group Delay ( $\mu\text{s}$ ) | | 18.5 | 14.1 | 12.1 | 8.3 | 12.1 | 12.3 | 11.6 | 10.1 | +| Impedance ( $\Omega$ )
at NTU | Re. | 124 | 88 | 65 | 49 | 68 | 75 | 68 | 52 | +| | Im. | –167 | –97 | –64 | –9 | 0 | –19 | –18 | 3 | +| Impedance ( $\Omega$ )
at LTU | Re. | 253 | 188 | 144 | 125 | 124 | 120 | 117 | 117 | +| | Im. | –200 | –133 | –88 | –43 | –29 | –21 | –14 | –13 | + +**Table II.13/G.991.1 – Loop 7** + +| Frequency (kHz) | | 10 | 20 | 40 | 100 | 150 | 200 | 400 | 500 | +|----------------------------------|-----|-----------|-----------|-----------|------------|------------|------------|------------|------------| +| Attenuation (dB) | | 14.1 | 17.7 | 22.1 | 28.0 | 30.6 | 33.1 | 45.2 | 50.9 | +| Phase (deg) | | –98 | –171 | –296 | –645 | –941 | –1237 | –2391 | –2801 | +| Group Delay ( $\mu\text{s}$ ) | | 22.9 | 18.4 | 16.6 | 16.3 | 16.3 | 16.7 | 15.8 | 15.5 | +| Impedance ( $\Omega$ )
at NTU | Re. | 124 | 86 | 57 | 48 | 70 | 96 | 73 | 61 | +| | Im. | –182 | –109 | –65 | –4 | +16 | –14 | +2 | –17 | +| Impedance ( $\Omega$ )
at LTU | Re. | 218 | 161 | 133 | 103 | 91 | 81 | 57 | 53 | +| | Im. | –218 | –135 | –90 | –59 | –53 | –49 | –31 | –21 | + +## APPENDIX III + +### Bibliography + +- [B1] LEE-FANG WEI: Rotationally Invariant Convolutional Coding with Expanded Signal Space – Part II: Nonlinear Codes, *IEEE Transactions on Information Theory*, Vol. IT-33, July 1984. +- [B2] CUPO (R.L.) et al: Combined Trellis Coding and DFE Through Tomlinson Precoding, *IEEE Journal on Selected Areas in Communications*, Vol. 9, No. 6, August 1991. +- [B3] Committee T1 Technical Report No. 28: A Technical Report on High bit rate Digital Subscriber Lines (HDSL), *February 1994*. +- [B4] BOYD (S.): Multitone Signals with Low Crest Factor, *IEEE Transactions on Circuits and Systems*, Vol. CAS-33 No. 10, October 1986. +- [B5] ETS 300 247 (1993), *Business Telecommunications (BT); Open Network Provision (ONP) technical requirements; 2048 kbit/s digital unstructured leased lines (D2048U); Connection characteristics*. +- [B6] ETS 300 418 (1995), *Business TeleCommunications (BTC); 2048 kbit/s digital unstructured and structured leased lines (D2048U and D2048S); Network interface presentation*. +- [B7] ETS 300 419 (1995), *Business TeleCommunications (BTC); 2048 kbit/s digital structured leased lines (D2048S); Connection characteristics*. +- [B8] ITU-T Recommendation G.823 (1993), *The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy*. +- [B9] ITU-T Recommendation G.826 (1996), *Error performance parameters and objectives for international, constant bit rate digital paths at or above the primary rate*. +- [B10] ITU-T Recommendation G.703 (1998), *Physical/electrical characteristics of hierarchical digital interfaces*. +- [B11] ITU-T Recommendation G.704 (1998), *Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels*. +- [B12] CCITT Recommendation G.706 (1991), *Frame alignment and cyclic redundancy check (CRC) procedures relating to basic frame structures defined in Recommendation G.704*. +- [B13] ISO 2110:1989, *Information Technology – Data communication – 25-pole DTE/DCE interface connector and connect number assignments*. +- [B14] ITU-T Recommendation G.707 (1996), *Network node interface for the synchronous digital hierarchy (SDH)*. +- [B15] ETS 300 167 (1993), *Transmission and Multiplexing (TM); Functional characteristics of 2048 kbit/s interfaces*. + + + +## ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure | +| Series Z | Programming languages | \ No newline at end of file diff --git a/marked/G/T-REC-G.992.1-199907-I_PDF-E/raw.md b/marked/G/T-REC-G.992.1-199907-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..4e8ad44095b53b4cf1f397ece68e6cd61b78093a --- /dev/null +++ b/marked/G/T-REC-G.992.1-199907-I_PDF-E/raw.md @@ -0,0 +1,8657 @@ + + +![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +**G.992.1** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +(06/99) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital transmission systems – Digital sections and digital +line system – Access networks + +--- + +**Asymmetric digital subscriber line (ADSL) +transceivers** + +ITU-T Recommendation G.992.1 + +(Previously CCITT Recommendation) + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| INTERNATIONAL ANALOGUE CARRIER SYSTEM | | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TRANSMISSION SYSTEMS | | +| TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | + +For further details, please refer to ITU-T List of Recommendations. + +# **ITU-T RECOMMENDATION G.992.1** + +# **ASYMMETRIC DIGITAL SUBSCRIBER LINE (ADSL) TRANSCEIVERS** + +## **Summary** + +This Recommendation describes Asymmetric Digital Subscriber Line (ADSL) Transceivers on a metallic twisted pair that allows high-speed data transmission between the network operator end (ATU-C) and the customer end (ATU-R). This Recommendation provides a variety of bearer channels in conjunction with one of three other services dependent on the environment: + +- 1) ADSL transmission simultaneously on the same pair with voice (band) service; +- 2) ADSL transmission simultaneously on the same pair with G.961 (Appendix I or II) ISDN services; or +- 3) ADSL transmission on the same pair with voiceband transmission and with TCM-ISDN (G.961 Appendix III) in an adjacent pair. + +Systems allow approximately 6 Mbit/s downstream and approximately 640 kbit/s upstream data rates depending on the deployment and noise environment. + +This Recommendation specifies the physical layer characteristics of the Asymmetric Digital Subscriber Line (ADSL) interface to metallic loops. + +This Recommendation has been written to help ensure the proper interfacing and interworking of ADSL transmission units at the customer end (ATU-R) and at the network operator end (ATU-C) and also to define the transport capability of the units. Proper operation shall be ensured when these two units are manufactured and provided independently. A single twisted pair of telephone wires is used to connect the ATU-C to the ATU-R. The ADSL transmission units must deal with a variety of wire pair characteristics and typical impairments (e.g. crosstalk and noise). + +An ADSL transmission unit can simultaneously convey all of the following: downstream simplex bearers, duplex bearers, a baseband analogue duplex channel, and ADSL line overhead for framing, error control, operations and maintenance. Systems support a minimum of 6.144 Mbit/s downstream and 640 kbit/s upstream. + +This Recommendation includes mandatory requirements, recommendations and options; these are designated by the words "shall", "should" and "may" respectively. The word "will" is used only to designate events that take place under some defined set of circumstances. + +Two categories of performance are specified. Category I performance is required for compliance with this Recommendation; performance enhancement options are not required for category I equipment. Category II is a higher level of performance (i.e. longer lines and greater impairments). Category II performance and characteristics are not required for compliance with this Recommendation. + +This Recommendation defines several optional capabilities and features: + +- echo cancellation; +- trellis coded modulation; +- dual latency; +- transport of a network timing reference; +- transport of STM and/or ATM; +- reduced overhead framing modes. + +It is the intention of this Recommendation to provide, by negotiation during initialization, for U-interface compatibility and interoperability between transceivers complying to this Recommendation and between transceivers that include different combinations of options. + +###### **Source** + +ITU-T Recommendation G.992.1 was prepared by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 22 June 1999. + +## FOREWORD + +ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. + +The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +### NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +## INTELLECTUAL PROPERTY RIGHTS + +The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, the ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2000 + +All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. + +## CONTENTS + +| | | Page | +|-------|-------------------------------------------------------|------| +| 1 | Scope | 1 | +| 1.1 | System reference model | 2 | +| 1.2 | Objectives | 2 | +| 2 | References | 3 | +| 3 | Definitions | 3 | +| 4 | Abbreviations | 6 | +| 5 | Reference Models | 9 | +| 5.1 | ATU-C transmitter reference models | 9 | +| 5.1.1 | ATU-C transmitter reference model for STM transport | 10 | +| 5.1.2 | ATU-C transmitter reference model for ATM transport | 11 | +| 5.2 | ATU-R transmitter reference models | 12 | +| 5.2.1 | ATU-R transmitter reference model for STM transport | 12 | +| 5.2.2 | ATU-R transmitter reference model for ATM transport | 13 | +| 5.3 | ATU-C/R transmitter timing model (Annex C only) | 13 | +| 6 | Transport capacity | 14 | +| 6.1 | Transport of STM data | 15 | +| 6.2 | Transport of ATM data | 16 | +| 6.3 | ADSL system overheads and total bit rates | 17 | +| 7 | ATU-C functional characteristics | 18 | +| 7.1 | STM Transmission Protocol Specific functionalities | 19 | +| 7.1.1 | ATU-C input and output V interfaces for STM transport | 19 | +| 7.1.2 | Downstream simplex channels – bit rates | 19 | +| 7.1.3 | Downstream/upstream duplex channels – bit rates | 19 | +| 7.1.4 | Payload transfer delay | 20 | +| 7.1.5 | Framing Structure for STM transport | 20 | +| 7.2 | ATM Transport Protocol Specific functionalities | 20 | +| 7.2.1 | ATU-C input and output V interface for ATM transport | 20 | +| 7.2.2 | Payload transfer delay | 21 | +| 7.2.3 | ATM Cell specific functionalities | 21 | +| 7.2.4 | Framing Structure for ATM transport | 23 | +| 7.3 | Network timing reference (NTR) | 24 | +| 7.3.1 | Need for NTR | 24 | +| 7.3.2 | Transport of the NTR | 24 | +| 7.4 | Framing | 25 | +| 7.4.1 | Data symbols | 25 | + +| | Page | +|-----------------------------------------------------------------------------|-------------| +| 7.4.2 Synchronization ..... | 33 | +| 7.4.3 Reduced overhead framing ..... | 35 | +| 7.5 Scramblers ..... | 37 | +| 7.6 Forward error correction ..... | 38 | +| 7.6.1 Reed-Solomon coding ..... | 38 | +| 7.6.2 Reed-Solomon Forward Error Correction Superframe Synchronization..... | 38 | +| 7.6.3 Interleaving ..... | 38 | +| 7.6.4 Support of higher downstream bit rates with $S = 1/2$ (optional)..... | 39 | +| 7.7 Tone ordering..... | 40 | +| 7.8 Constellation encoder (trellis code version) ..... | 42 | +| 7.8.1 Bit extraction ..... | 42 | +| 7.8.2 Bit conversion..... | 43 | +| 7.8.3 Coset partition and trellis diagram..... | 43 | +| 7.8.4 Constellation encoder ..... | 47 | +| 7.9 Constellation encoder – No trellis coding..... | 50 | +| 7.9.1 Bit extraction ..... | 50 | +| 7.9.2 Constellation encoder ..... | 50 | +| 7.10 Gain scaling ..... | 50 | +| 7.11 Modulation..... | 51 | +| 7.11.1 Subcarriers ..... | 51 | +| 7.11.2 Modulation by the inverse discrete Fourier transform (IDFT) ..... | 51 | +| 7.11.3 Synchronization symbol ..... | 52 | +| 7.11.4 Inverse synchronization symbol (Annex C only) ..... | 52 | +| 7.12 Cyclic prefix..... | 53 | +| 7.13 Transmitter dynamic range ..... | 53 | +| 7.13.1 Maximum clipping rate ..... | 53 | +| 7.13.2 Noise/distortion floor..... | 53 | +| 7.14 ATU-C Downstream Transmitter spectral masks..... | 54 | +| 7.15 Dual Bitmapping and Rate Conversion (Annex C only) ..... | 54 | +| 7.16 FEXT Bitmapping (Annex C only)..... | 54 | +| 8 ATU-R Functional Characteristics ..... | 54 | +| 8.1 STM Transmission Protocol Specific functionalities ..... | 54 | +| 8.1.1 ATU-R input and output T interfaces for STM transport..... | 54 | +| 8.1.2 Downstream simplex channels – Transceiver bit rates..... | 55 | +| 8.1.3 Duplex channels – Transceiver bit rates..... | 55 | +| 8.1.4 Framing Structure for STM transport ..... | 55 | +| 8.2 ATM Transport Protocol Specific functionalities..... | 56 | +| 8.2.1 ATU-R input and output T interfaces for ATM transport ..... | 56 | + +| | Page | +|------------------------------------------------------------------|-------------| +| 8.2.2 ATM Cell specific functionalities ..... | 56 | +| 8.2.3 Framing Structure for ATM transport ..... | 56 | +| 8.3 Network timing reference ..... | 57 | +| 8.4 Framing..... | 57 | +| 8.4.1 Data symbols ..... | 57 | +| 8.4.2 Synchronization ..... | 61 | +| 8.4.3 Reduced overhead framing..... | 63 | +| 8.5 Scramblers ..... | 63 | +| 8.6 Forward error correction..... | 63 | +| 8.7 Tone ordering..... | 63 | +| 8.8 Constellation encoder – Trellis version ..... | 64 | +| 8.9 Constellation encoder – Uncoded version ..... | 64 | +| 8.10 Gain scaling ..... | 64 | +| 8.11 Modulation..... | 64 | +| 8.11.1 Subcarriers ..... | 64 | +| 8.11.2 Modulation by the inverse discrete Fourier transform..... | 65 | +| 8.11.3 Synchronization symbol ..... | 65 | +| 8.11.4 Inverse synchronization symbol (Annex C only) ..... | 65 | +| 8.12 Cyclic prefix..... | 65 | +| 8.13 Transmitter dynamic range ..... | 65 | +| 8.13.1 Maximum clipping rate ..... | 65 | +| 8.13.2 Noise/distortion floor..... | 65 | +| 8.14 ATU-R Upstream Transmitter spectral response..... | 66 | +| 8.15 Dual Bitmapping and Rate Conversion (Annex C only) ..... | 66 | +| 8.16 FEXT Bitmapping (Annex C only)..... | 66 | +| 9 EOC Operations and Maintenance..... | 66 | +| 9.1 Clear EOC..... | 66 | +| 9.2 Embedded operations channel (EOC) requirements ..... | 67 | +| 9.2.1 EOC organization and protocol ..... | 67 | +| 9.2.2 EOC message structure..... | 67 | +| 9.2.3 EOC message sets..... | 68 | +| 9.2.4 Data registers in the ATU-R ..... | 72 | +| 9.2.5 EOC protocol states ..... | 73 | +| 9.3 In-service performance monitoring and surveillance..... | 80 | +| 9.3.1 ADSL line related primitives..... | 81 | +| 9.3.2 STM data path related primitives ..... | 83 | +| 9.3.3 ATM data path related primitives..... | 83 | +| 9.3.4 Other ADSL indicators, parameters and signals..... | 85 | + +| | Page | | +|---------|--------------------------------------------------------------------------|----| +| 9.4 | Failures and Performance Parameters..... | 85 | +| 9.5 | Test Parameters..... | 85 | +| 9.5.1 | Near-end test parameters ..... | 85 | +| 9.5.2 | Far-end test parameters..... | 86 | +| 10 | Initialization..... | 86 | +| 10.1 | Overview..... | 86 | +| 10.1.1 | Basic functions of initialization..... | 86 | +| 10.1.2 | Transparency to methods of separating upstream and downstream signals .. | 87 | +| 10.1.3 | Implementation of service options for ADSL..... | 87 | +| 10.1.4 | Resetting during initialization and data transmission..... | 87 | +| 10.1.5 | Initialization with Hyperframe (Annex C only)..... | 88 | +| 10.2 | Handshake – ATU-C..... | 88 | +| 10.2.1 | CL messages ..... | 88 | +| 10.2.2 | MS messages ..... | 88 | +| 10.3 | Handshake – ATU-R..... | 89 | +| 10.3.1 | CLR messages ..... | 89 | +| 10.3.2 | MS messages ..... | 90 | +| 10.4 | Transceiver training – ATU-C ..... | 91 | +| 10.4.1 | C-QUIET2 ..... | 91 | +| 10.4.2 | C-PILOT1 ..... | 91 | +| 10.4.3 | C-PILOT1A ..... | 92 | +| 10.4.4 | C-QUIET3A ..... | 92 | +| 10.4.5 | C-REVERB1 ..... | 92 | +| 10.4.6 | C-PILOT2 ..... | 93 | +| 10.4.7 | C-ECT..... | 93 | +| 10.4.8 | C-REVERB2 ..... | 93 | +| 10.4.9 | C-QUIET5 ..... | 93 | +| 10.4.10 | C-PILOT3 ..... | 93 | +| 10.4.11 | C-REVERB3 ..... | 93 | +| 10.5 | Transceiver training – ATU-R ..... | 93 | +| 10.5.1 | R-QUIET2 ..... | 93 | +| 10.5.2 | R-REVERB1 ..... | 94 | +| 10.5.3 | R-QUIET3 ..... | 94 | +| 10.5.4 | R-ECT..... | 94 | +| 10.5.5 | R-REVERB2 ..... | 95 | +| 10.6 | Channel analysis (ATU-C)..... | 95 | +| 10.6.1 | C-SEGUE1 ..... | 95 | +| 10.6.2 | C-RATES1..... | 95 | +| 10.6.3 | C-CRC1 ..... | 96 | + +| | Page | +|------------------------------------|-------------| +| 10.6.4 C-MSG1..... | 97 | +| 10.6.5 C-CRC2..... | 98 | +| 10.6.6 C-MEDLEY..... | 98 | +| 10.7 Channel analysis (ATU-R)..... | 99 | +| 10.7.1 R-SEGUE1..... | 99 | +| 10.7.2 R-REVERB3..... | 99 | +| 10.7.3 R-SEGUE2..... | 99 | +| 10.7.4 R-RATES1..... | 99 | +| 10.7.5 R-CRC1..... | 100 | +| 10.7.6 R-MSG1..... | 100 | +| 10.7.7 R-CRC2..... | 101 | +| 10.7.8 R-MEDLEY..... | 101 | +| 10.7.9 R-REVERB4..... | 102 | +| 10.8 Exchange – ATU-C..... | 103 | +| 10.8.1 C-REVERB4..... | 104 | +| 10.8.2 C-SEGUE2..... | 104 | +| 10.8.3 C-RATES-RA..... | 104 | +| 10.8.4 C-CRC-RA1..... | 105 | +| 10.8.5 C-MSG-RA..... | 106 | +| 10.8.6 C-CRC-RA2..... | 106 | +| 10.8.7 C-REVERB-RA..... | 106 | +| 10.8.8 C-SEGUE-RA..... | 106 | +| 10.8.9 C-MSG2..... | 106 | +| 10.8.10 C-CRC3..... | 108 | +| 10.8.11 C-RATES2..... | 108 | +| 10.8.12 C-CRC4..... | 109 | +| 10.8.13 C-B&G..... | 109 | +| 10.8.14 C-CRC5..... | 109 | +| 10.8.15 C-REVERB5..... | 109 | +| 10.8.16 C-SEGUE3..... | 110 | +| 10.9 Exchange – ATU-R..... | 110 | +| 10.9.1 R-SEGUE3..... | 110 | +| 10.9.2 R-MSG-RA..... | 110 | +| 10.9.3 R-CRC-RA1..... | 111 | +| 10.9.4 R-RATES-RA..... | 112 | +| 10.9.5 R-CRC-RA2..... | 112 | +| 10.9.6 R-REVERB-RA..... | 112 | +| 10.9.7 R-SEGUE-RA..... | 112 | +| 10.9.8 R-MSG2..... | 113 | +| 10.9.9 R-CRC3..... | 114 | + +| | Page | +|-----------------------------------------------------------------------------------------------|-------------| +| 10.9.10 R-RATES2 | 114 | +| 10.9.11 R-CRC4 | 114 | +| 10.9.12 R-REVERB5 | 115 | +| 10.9.13 R-SEGUE4 | 115 | +| 10.9.14 R-B&G | 115 | +| 10.9.15 R-CRC5 | 116 | +| 10.9.16 R-REVERB6 | 116 | +| 10.9.17 R-SEGUE5 | 116 | +| 10.9.18 Details of Initialization timing | 116 | +| 11 AOC on-line adaptation and reconfiguration | 119 | +| 11.1 The ADSL overhead control (AOC) channel | 119 | +| 11.1.1 AOC message header | 119 | +| 11.1.2 AOC protocol | 119 | +| 11.2 On-line adaptation – Bit swapping | 120 | +| 11.2.1 Bit swap channel | 120 | +| 11.2.2 Superframe counting | 120 | +| 11.2.3 Bit swap request | 120 | +| 11.2.4 Extended bit swap request | 121 | +| 11.2.5 Bit swap acknowledge | 122 | +| 11.2.6 Bit swap – Receiver | 122 | +| 11.2.7 Bit swap – Transmitter | 123 | +| Annex A – Specific requirements for an ADSL system operating in the frequency band above POTS | 123 | +| A.1 ATU-C Functional Characteristics (pertains to clause 7) | 123 | +| A.1.1 Pilot Frequency (supplements 7.11.1.2) | 123 | +| A.1.2 ATU-C downstream transmit spectral mask (replaces 7.14) | 123 | +| A.1.3 ATU-C transmitter PSD mask for reduced NEXT | 127 | +| A.2 ATU-R (see clause 8) | 128 | +| A.2.1 Modulation by the inverse discrete Fourier transform (see 8.11.2) | 128 | +| A.2.2 Synchronization symbol (supplements 8.11.3) | 129 | +| A.2.3 Cyclic prefix (replaces 8.12) | 129 | +| A.2.4 ATU-R transmitter spectral mask (replaces 8.14) | 129 | +| A.2.5 Nyquist frequency (supplements 8.11.1.2) | 132 | +| A.3 Initialization (see clause 10) | 133 | +| A.3.1 Power cut-back (supplements 10.4.5.1) | 133 | +| A.3.2 Estimated average upstream loop attenuation (see 10.8.9.1) | 133 | +| A.3.3 Estimated average downstream loop attenuation (supplements 10.9.8.1) | 133 | +| A.3.4 C-PILOT1 (supplements 10.4.2) | 133 | +| A.3.5 R-REVERB1 (see 10.5.2) | 133 | + +| | Page | +|------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------| +| A.3.6 C-ECT (see 10.4.7) | 133 | +| A.3.7 R-ECT (see 10.5.4) | 133 | +| A.3.8 C-MSG2 (supplements 10.8.9) | 134 | +| A.3.9 R-MSG2 (supplements 10.9.8) | 134 | +| A.4 Electrical characteristics (new) | 134 | +| A.4.1 DC characteristics | 134 | +| A.4.2 Voiceband characteristics | 134 | +| A.4.3 ADSL band characteristics | 135 | +| Annex B – Specific requirements for an ADSL system operating in the frequency band above ISDN as defined in ITU-T Recommendation G.961 Appendices I and II | 136 | +| B.1 ATU Functional Characteristics (see clause 7) | 136 | +| B.1.1 Data Subcarriers (see 7.11.1.1) | 136 | +| B.1.2 Pilot Frequency (see 7.11.1.2) | 136 | +| B.1.3 Downstream transmit spectral mask (replaces 7.14) | 136 | +| B.2 ATU-R functional characteristics (see clause 8) | 140 | +| B.2.1 ATU-R transmit reference models | 140 | +| B.2.2 ATU-R Upstream transmit spectral mask (replaces 8.14) | 141 | +| B.2.3 Data subcarriers (replaces 8.11.1.1) | 143 | +| B.2.4 Pilot frequency | 144 | +| B.2.5 Nyquist frequency (supplements 8.11.1.2) | 144 | +| B.2.6 Modulation by the Inverse Discrete Fourier Transform (replaces 8.11.2) | 144 | +| B.2.7 Synchronization symbol (supplements 8.11.3) | 144 | +| B.2.8 Cyclic prefix (replaces 8.12) | 144 | +| B.3 Initialization (see clause 10) | 145 | +| B.3.1 Handshake – ATU-C (supplements 10.2) | 145 | +| B.3.2 Handshake – ATU-R (supplements 10.3) | 145 | +| B.3.3 Power Cut-back (supplements 10.4.5.1) | 146 | +| B.3.4 Estimated average upstream loop attenuation (see 10.8.9.1) | 146 | +| B.3.5 Estimated average downstream loop attenuation (10.9.8.1) | 146 | +| B.3.6 C-PILOT1 (for 10.4.3) | 146 | +| B.3.7 R-REVERB1 (supplements 10.5.2) | 146 | +| B.3.8 R-MEDLEY (replaces 10.7.8) | 147 | +| B.3.9 C-MSG2 (supplements 10.8.9) | 147 | +| B.3.10 R-MSG2 (supplements 10.9.8) | 147 | +| B.3.11 C-ECT and R-ECT (supplements 10.4.7 and 10.5.4) | 147 | +| B.3.12 C-B&G (replaces 10.8.13) | 147 | +| Annex C – Specific requirements for an ADSL system operating in the same cable as ISDN as defined in ITU-T Recommendation G.961 Appendix III | 150 | +| C.1 Scope | 150 | + +| | Page | +|----------------------------------------------------------------------------------|-------------| +| C.2 Definitions ..... | 150 | +| C.3 Reference Models ..... | 151 | +| C.3.1 ATU-C transmitter reference model (replaces figures in 5.1) ..... | 151 | +| C.3.2 ATU-R transmitter reference model (replaces figures in 5.2) ..... | 153 | +| C.3.3 ATU-C/R transmitter timing model (replacement for 5.3)..... | 155 | +| C.4 ATU-C functional characteristics (pertains to clause 7)..... | 158 | +| C.4.1 STM transmission protocols specific functionality (pertains to 7.1)..... | 158 | +| C.4.2 ATM transmission protocols specific functionalities (pertains to 7.2)..... | 159 | +| C.4.3 Framing (pertains to 7.4) ..... | 159 | +| C.4.4 Dual Bitmapping and Rate Conversion (replaces 7.15) ..... | 164 | +| C.4.5 FEXT Bitmapping (replaces 7.16)..... | 166 | +| C.4.6 Tone Ordering (replacement for 7.7)..... | 167 | +| C.4.7 Modulation (pertains to 7.11) ..... | 167 | +| C.4.8 ATU-C Downstream transmit spectral mask (replaces 7.14)..... | 167 | +| C.5 ATU-R Functional Characteristics (pertains to clause 8) ..... | 168 | +| C.5.1 Framing (pertains to 8.4) ..... | 168 | +| C.5.2 Dual Bitmapping and rate conversion (replaces 8.15)..... | 171 | +| C.5.3 FEXT Bitmapping (replaces 8.16)..... | 173 | +| C.5.4 Tone Ordering (pertains to 8.7) ..... | 173 | +| C.5.5 Modulation (pertains to 8.11) ..... | 173 | +| C.5.6 ATU-R Upstream Transmit Spectral Mask (supplements 8.14) ..... | 174 | +| C.6 EOC Operation and Maintenance (pertains to clause 9)..... | 174 | +| C.6.1 ADSL line related primitives (supplements 9.3.1) ..... | 174 | +| C.6.2 Test Parameters (supplements 9.5)..... | 174 | +| C.7 Initialization ..... | 174 | +| C.7.1 Initialization with Hyperframe (replaces 10.1.5)..... | 174 | +| C.7.2 Handshake – ATU-C (supplements 10.2)..... | 178 | +| C.7.3 Handshake – ATU-R (supplements 10.3)..... | 178 | +| C.7.4 Transceiver Training – ATU-C (supplements 10.4)..... | 179 | +| C.7.5 Transceiver Training – ATU-R (supplements 10.5)..... | 180 | +| C.7.6 Channel analysis (ATU-C) (supplements 10.6)..... | 181 | +| C.7.7 Channel analysis (ATU-R) (supplements 10.7)..... | 183 | +| C.7.8 R-SEGUE1 (supplements 10.7.1)..... | 184 | +| C.7.9 Exchange – ATU-C (supplements 10.8)..... | 185 | +| C.7.10 Exchange – ATU-R (supplements 10.9) ..... | 186 | +| C.8 AOC On-line adaptation and reconfiguration (pertains to clause 11) ..... | 191 | +| Annex D – ATU-C and ATU-R state diagrams ..... | 192 | +| D.1 Introduction..... | 192 | +| D.2 Definitions ..... | 192 | + +| | Page | +|-----------------------------------------------------------------------------|-------------| +| D.3 State Diagrams | 193 | +| Annex E – POTS and ISDN-BA splitters | 198 | +| E.1 Type 1 – European | 198 | +| E.1.1 Impedance matching | 198 | +| E.1.2 Return loss | 198 | +| E.1.3 Insertion loss | 199 | +| E.1.4 Insertion loss distortion | 199 | +| E.1.5 Isolation | 199 | +| E.1.6 Signal power | 199 | +| E.1.7 Ringing | 199 | +| E.1.8 Unbalance about Earth (ETS-300.001, § 4.2.1 and § 4.2.2) | 199 | +| E.1.9 Frequencies and levels for pulse metering (ETS-300.001, § 1.7.8) | 200 | +| E.2 Type 2 – North America | 200 | +| E.2.1 Introduction | 200 | +| E.2.2 DC characteristics | 203 | +| E.2.3 Voiceband characteristics | 203 | +| E.2.4 ADSL band testing | 209 | +| E.2.5 Home premises physical considerations | 211 | +| E.3 Type 3 – ADSL above ISDN (ITU-T G.961 Appendix I or II) | 211 | +| E.4 Type 4 – Type for Japan | 212 | +| E.4.1 Introduction | 212 | +| E.4.2 DC Characteristics | 212 | +| E.4.3 AC Characteristics | 214 | +| Annex F – ATU-x Classification and Performance for Region A (North America) | 219 | +| F.1 Classification definitions | 219 | +| F.2 Performance requirements | 219 | +| F.2.1 Crosstalk interference | 220 | +| F.2.2 Impulse noise | 221 | +| F.2.3 POTS | 222 | +| Annex G – ATU-x Classification and Performance for Region B (Europe) | 223 | +| G.1 Performance requirements | 223 | +| Appendix I – ATM Layer to Physical Layer Logical Interface | 224 | +| Appendix II – Dynamic (on-line) Rate Adaptation | 226 | +| II.1 Introduction | 226 | +| II.1.1 General concepts | 227 | + +| | Page | +|---------------------------------------------------------------------|-------------| +| II.2 DRA protocol and messages | 227 | +| II.2.1 DRA concept | 227 | +| II.2.2 DRA-AOC messages | 227 | +| II.3 Monitoring | 228 | +| II.3.1 DRA_Monitor_Request | 228 | +| II.3.2 DRA_Monitor_Reply | 228 | +| II.4 Configuration | 229 | +| II.4.1 DRA_Configuration_Request | 229 | +| II.4.2 DRA_Configuration_Reply | 230 | +| II.5 Exchange | 231 | +| II.5.1 DRA_Exchange_Request | 231 | +| II.5.2 DRA_Exchange_Reply | 232 | +| II.6 Swap | 233 | +| II.6.1 Example | 235 | +| II.6.2 DRA_Swap_Request | 235 | +| II.6.3 DRA_Swap_Reply | 236 | +| II.7 DRA state diagram | 237 | +| II.7.1 State machine conventions | 237 | +| II.7.2 ATU-R state machine | 238 | +| II.7.3 ATU-C state machine | 239 | +| Appendix III – Compatibility with other customer premises equipment | 240 | +| Appendix IV – Bibliography | 240 | + +## **Recommendation G.992.1** + +### **ASYMMETRIC DIGITAL SUBSCRIBER LINE (ADSL) TRANSCEIVERS** + +*(Geneva, 1999)* + +#### **1 Scope** + +For interrelationships of this Recommendation with other G.99x-series Recommendations, see Recommendation G.995.1. + +This Recommendation describes the interface between the telecommunications network and the customer installation in terms of their interaction and electrical characteristics. The requirements of this Recommendation apply to a single asymmetric digital subscriber line (ADSL). + +ADSL provides a variety of bearer channels in conjunction with other services: + +- ADSL service on the same pair with voiceband services (including POTS and voiceband data services). The ADSL occupies a frequency band above the voiceband, and is separated from it by filtering; +- ADSL on the same pair as ISDN as defined in Recommendation G.961 Appendices I and II. The ADSL occupies a frequency band above the ISDN, and is separated from it by filtering; +- ADSL service on the same pair with voiceband services (including POTS and voiceband data services), and with ISDN as defined in Recommendation G.961 Appendix III in an adjacent pair. + +In the direction from the network operator to the customer premises (i.e. downstream), the bearer channels may consist of full duplex low-speed bearer channels and simplex high-speed bearer channels; in the other direction (i.e. upstream), only low-speed bearer channels are provided. + +The transmission system is designed to operate on two-wire twisted metallic cable pairs with mixed gauges. This Recommendation is based on the use of cables without loading coils, but bridged taps are acceptable in all but a few unusual situations. + +Specifically, this Recommendation: + +- defines the combined options and ranges of the simplex and full-duplex bearer channels provided; +- defines the line code and the spectral composition of the signals transmitted by both ATU-C and ATU-R; +- specifies the transmit signals at both the ATU-C and ATU-R; +- describes the organization of transmitted and received data into frames; +- defines the functions of the operations channel; +- defines the ATU-R to service module(s) interface functions; +- defines the Transmission Convergence Sublayer for ATM transport. + +In Annexes A, B and C it also: + +- describes the transmission technique used to support the simultaneous transport on a single twisted-pair of voiceband services and both simplex and duplex bearer channels; +- describes the transmission technique used to support the simultaneous transport on a single twisted-pair of ISDN services as defined in Recommendation G.961 Appendices I and II, and both simplex and duplex bearer channels; + +- describes the transmission technique used to support the simultaneous transport on a single twisted-pair of voiceband services and both simplex and duplex bearer channels when they are subject to crosstalk from ISDN as defined in Recommendation G.961 Appendix III. + +### 1.1 System reference model + +The system reference model shown in Figure 1-1 illustrates the functional blocks required to provide ADSL service. + +![Figure 1-1/G.992.1 – ADSL system reference model. The diagram illustrates the functional blocks and interfaces of an ADSL system. At the top level, it shows a chain of blocks: Core Network, Access Network, NT1, NT2, TA, and User Terminal, connected by reference points V, U, T, S, and R respectively. Below this, a detailed functional breakdown is shown. On the network side (left), a Broadband network connects via a PHY block to an ATU-C, and a Narrowband network (PSTN or ISDN) connects to a Splitter C. These converge at the U-C interface. On the customer side (right), the line enters Splitter R, which separates signals for the ATU-R (via high-pass filter h-p) and POTS/ISDN service (via low-pass filter l-p). The ATU-R connects via a PHY block to the Customer Premises network, which includes Service Modules (SM) and terminals like telephone sets or voiceband modems. Interfaces shown include SNI, XNI, V-C, U-C 2, U-R 2, T-R, and T/S. A legend indicates solid lines for signal lines and dashed lines for interfaces. Reference number T1532320-99 is in the bottom right.](1a827b10290f33d4fec04d0e8ef7a897_img.jpg) + +Figure 1-1/G.992.1 – ADSL system reference model. The diagram illustrates the functional blocks and interfaces of an ADSL system. At the top level, it shows a chain of blocks: Core Network, Access Network, NT1, NT2, TA, and User Terminal, connected by reference points V, U, T, S, and R respectively. Below this, a detailed functional breakdown is shown. On the network side (left), a Broadband network connects via a PHY block to an ATU-C, and a Narrowband network (PSTN or ISDN) connects to a Splitter C. These converge at the U-C interface. On the customer side (right), the line enters Splitter R, which separates signals for the ATU-R (via high-pass filter h-p) and POTS/ISDN service (via low-pass filter l-p). The ATU-R connects via a PHY block to the Customer Premises network, which includes Service Modules (SM) and terminals like telephone sets or voiceband modems. Interfaces shown include SNI, XNI, V-C, U-C 2, U-R 2, T-R, and T/S. A legend indicates solid lines for signal lines and dashed lines for interfaces. Reference number T1532320-99 is in the bottom right. + +NOTE 1 – The U-C and U-R interfaces are fully defined in this Recommendation. The V-C and T-R interfaces are defined only in terms of logical functions, not physical. The T/S interface is not defined here. + +NOTE 2 – The V-C interface may consist of interface(s) to one or more (STM or ATM) switching systems. + +NOTE 3 – Implementation of the V-C and T-R interfaces is optional when interfacing elements are integrated into a common element. + +NOTE 4 – One or other of the high-pass filters, which are part of the splitters, may be integrated into the ATU-x; if so, then the U-C 2 and U-R 2 interfaces become the same as the U-C and U-R interfaces, respectively. + +NOTE 5 – A digital carrier facility (e.g. SONET extension) may be interposed at the V-C. + +NOTE 6 – Due to the asymmetry of the signals on the line, the transmitted signals shall be distinctly specified at the U-R and U-C reference points. + +NOTE 7 – The nature of the customer installation distribution and customer premises network (e.g. bus or star, type of media) is for further study. + +NOTE 8 – More than one type of T-R interface may be defined, and more than one type of T/S interface may be provided from an ADSL NT (e.g. NT1 or NT2 types of functionalities). + +NOTE 9 – A future issue of this Recommendation may deal with customer installation distribution and home network requirements. + +NOTE 10 – Specifications for the splitters are given in Annex E. + +**Figure 1-1/G.992.1 – ADSL system reference model** + +### 1.2 Objectives + +This Recommendation defines the minimal set of requirements to provide satisfactory simultaneous transmission between the network and the customer interface of a variety of high-speed simplex and low-speed duplex channels and other services such as POTS or ISDN. This Recommendation permits network providers an expanded use of existing copper facilities. All physical layer aspects required to ensure compatibility between equipment in the network and equipment at a remote + +location are specified. Equipment may be implemented with additional functions and procedures. + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. + +- ITU-T Recommendation G.961 (1993), *Digital transmission system on metallic local lines for ISDN basic rate access.* +- ITU-T Recommendation G.994.1 (1999), *Handshake procedures for Digital Subscriber Line (DSL) transceivers.* +- ITU-T Recommendation G.996.1 (1999), *Test procedures for Digital Subscriber Line (DSL) transceivers.* +- ITU-T Recommendation G.997.1 (1999), *Physical layer management for Digital Subscriber Line (DSL) transceivers.* +- ITU-T Recommendation I.361 (1999), *B-ISDN ATM layer specification.* +- ITU-T Recommendation I.432.1 (1999), *B-ISDN user-network interface – Physical layer specification: General characteristics.* + +**For Annex B** + +- ETSI TS 102 080 V1.3.1 (1998), *Transmission and Multiplexing (TM); Integrated Services Digital Network (ISDN) basic rate access; Digital transmission system on metallic local lines.* + +**For Annex E** + +- ITU-T Recommendation G.117 (1996), *Transmission aspects of unbalance about earth.* +- ITU-T Recommendation Q.552 (1996), *Transmission characteristics at 2-wire analogue interfaces of digital exchanges.* +- ETSI ETS 300 001 ed.4 (1997), *Attachments to the Public Switched Telephone Network (PSTN); General technical requirements for equipment connected to an analogue subscriber interface in the PSTN.* + +## 3 Definitions + +This Recommendation defines the following terms: + +**3.1 ADSL Lines:** See 5.1/G.997.1. + +**3.2 ADSL system overhead:** All overhead needed for system control, including CRC, EOC, AOC synchronization bytes, fixed indicator bits for OAM, and FEC; that is, the difference between total data rate and net data rate. + +**3.3 aggregate data rate:** Data rate transmitted by an ADSL system in any one direction; it includes both net data rate and overhead used by the system for EOC, AOC, CRC check bytes, fixed indicator bits for OAM, synchronization control bytes and capacity for bearer channel synchronization control (i.e. $K_F + K_I$ times 32 kbit/s); it does not include Reed-Solomon FEC redundancy. + +**3.4 anomalies:** An anomaly is a discrepancy between the actual and desired characteristics of an item. The desired characteristics may be expressed in the form of a specification. An anomaly may or may not affect the ability of an item to perform a required function. Performance anomalies are defined in 9.3.1.1 (see Figure 9-4). + +**3.5 bearer channel:** A user data stream of a specified data rate that is transported transparently by an ADSL system. + +**3.6 bridged taps:** Sections of unterminated twisted-pair cables connected in parallel across the cable under consideration. + +**3.7 category I:** Basic category of transceivers with no performance-enhancing options, which meet a basic set of performance requirements. + +**3.8 category II:** Category of transceivers with performance-enhancing options which meet an expanded set of performance requirements. + +**3.9 channelization:** Allocation of the net data rate to bearer channels. + +**3.10 data frame:** A grouping of bytes from fast and interleaved paths over a single symbol time period after addition of FEC bytes and after interleaving (at reference point C of Figure 7-5). + +**3.11 data symbol rate:** The net average rate (after allowing for the overhead of the synchronization symbol) at which symbols carrying user data are transmitted (= 4 kbaud). + +**3.12 dBrn:** Ratio (in decibels) of a power level with respect to a reference power of 1 pico-Watt (equivalent –90 dBm) (reference: Recommendation O.41 – Annex A). + +**3.13 defects:** A defect is a limited interruption in the ability of an item to perform a required function. It may or may not lead to maintenance action depending on the results of additional analysis. Successive anomalies causing a decrease in the ability of an item to perform a required function are considered as a defect (see Figure 9-4). + +**3.14 DMT symbol:** A set of complex values $\{Z_i\}$ forming the frequency domain inputs to the inverse discrete Fourier transform (IDFT) (see 7.11.2). The DMT symbol is equivalently the set of real valued time samples, $\{x_n\}$ , related to the set of $\{Z_i\}$ via the IDFT. + +**3.15 downstream:** The transport of data in the ATU-C to ATU-R direction. + +**3.16 dual latency:** Simultaneous transport of multiple data bearer channels in any one direction, in which user data is allocated to both the fast and interleaved paths; that is, $\text{sum}(B_F) > 0$ and $\text{sum}(B_I) > 0$ . + +**3.17 embedded operations channel:** A component of ADSL system overhead which provides communications between management entities in the ATU-C and ATU-R. It includes both clear channel and stateful messaging modes. + +**3.18 far-end:** Far-end means performance of the downstream loop-side received signal at the input of the ATU-R, where this performance is reported to the ATU-C in upstream indicators (see Figure 9-4), or performance of the upstream loop-side received signal at the input of the ATU-C, where this performance is reported to the ATU-R in downstream overhead indicators; this case is a mirror image of the above (see Figure 9-4). + +- 3.19 FEC output data frame:** The grouping of bytes from fast or interleaved path over a single symbol time period after addition of FEC bytes and before interleaving (at reference point B, Figures 7-8, and 7-9). +- 3.20 indicator bits:** Bits used for OAM purposes; embedded in the synchronization bytes. +- 3.21 loading coils:** Inductors placed in series with the cable at regular intervals in order to improve the voiceband response; removed for DSL use. +- 3.22 Mux data frame:** The grouping of bytes from fast or interleaved path over a single symbol time period before addition of FEC bytes and before interleaving (at reference point A, Figures 7-8 and 7-9). +- 3.23 near-end:** Near-end means performance of the loop-side received signal at the input of the ATU (see Figure 9-4). +- 3.24 net data rate:** Data rate that is available for user data in any one direction; for the downstream direction this is the sum of the net simplex and duplex data rates. +- 3.25 network timing reference:** An 8 kHz timing marker used to support the distribution of a timing reference over the network. +- 3.26 primitives:** Primitives are basic measures of performance, usually obtained from digital signal line codes and frame formats, or as reported in overhead indicators from the far-end. Performance primitives are categorized as events, anomalies and defects. Primitives may also be basic measures of other quantities (e.g. ac or battery power), usually obtained from equipment indicators (see Figure 9-4). +- 3.27 subcarrier:** A particular complex valued input, $Z_i$ , to the IDFT (see 7.11.2). +- 3.28 showtime:** The state of either ATU-C or ATU-R – reached after all initialization and training is completed – in which user data is transmitted. +- 3.29 single latency:** Simultaneous transport of one or more bearer channels in any one direction, in which all user data is allocated to either the fast or the interleaved path; that is, either $\text{sum}(B_F) > 0$ or $\text{sum}(B_I) > 0$ . +- 3.30 splitter:** Filter that separates the high frequency signals (ADSL) from the voiceband signals; (frequently called POTS splitter even though the voiceband signals may comprise more than POTS). +- 3.31 superframe:** A grouping of 68 data symbols and one synchronization symbol, over a total time duration of 17 ms (see Figure 7-5). +- 3.32 symbol rate:** The rate at which all symbols, including the synchronization symbol, are transmitted $[(69/68)*4.0 = 4.0588 \text{ kbaud}]$ ; contrasted with the data symbol rate. +- 3.33 sync byte:** An overhead byte present at the beginning of each mux data frame (called "fast" byte in the fast path and "sync" byte in the interleaved path). +- 3.34 sync frame:** A frame with deterministic content sent in the 69th symbol of a superframe (called "synchronization symbol" in Figure 7-5). +- 3.35 thresholds:** See clause 8/G.997.1. +- 3.36 Threshold Crossing Alert:** See Recommendation G.997.1. +- 3.37 total data rate:** Aggregate data rate plus FEC overhead. +- 3.38 upstream:** The transport of data in the ATU-R to ATU-C direction. +- 3.39 voiceband:** 0 to 4 kHz; expanded from the traditional 0.3 to 3.4 kHz to deal with voiceband data services wider than POTS. +- 3.40 voiceband services:** POTS and all data services that use the voiceband or some part of it. + +## 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------------|---------------------------------------------------------------------------------------------------------------------------------------------------------| +| ADC | Analogue-to-digital converter | +| ADSL | Asymmetric digital subscriber line | +| AEX | A(S) extension byte: byte inserted in the transmitted ADSL frame structure to provide Synchronization capacity that is shared among ASx bearer channels | +| AFE | Analogue Front End | +| AGC | Automatic gain control | +| AOC | ADSL overhead control channel | +| AS0 to AS3 | Downstream simplex bearer channel designators | +| ASx | Any one of the simplex bearer channels AS0 to AS3 | +| ATM | Asynchronous transfer mode | +| ATU | ADSL Transceiver Unit | +| ATU-C | ATU at the central office end (i.e. network operator) | +| ATU-R | ATU at the remote terminal end (i.e. CP) | +| ATU-x | Any one of ATU-C or ATU-R | +| BER | Bit Error Rate | +| $B_F$ | The number of bytes per frame in a data stream allocated to the fast (i.e. non-interleaved) buffer | +| $B_I$ | The number of bytes per frame in a data stream allocated to the interleaved buffer | +| $B_i$ | Number of bits allocated to subcarrier index i | +| BRA | Basic rate access | +| C-B&G | Central Office Bits and Gains Information | +| CI | Customer installation | +| CLP | Cell Loss Priority | +| CO | Central office | +| CP | Customer Premises | +| CRC | Cyclic Redundancy Check | +| CRC-8f | Cyclic redundancy check using CRC-8-fast data | +| CRC-8i | Cyclic redundancy check using CRC-8-interleaved data | +| CSA | Carrier serving area | +| DAC | Digital-to-analogue converter | +| DB | Dual Bitmap (Annex C) | +| DC | Direct current | +| DF | Data Frame | +| DMT | Discrete multitone | +| DSL | Digital subscriber line | +| EC | Echo cancelling | +| EOC | Embedded operations channel (between the ATU-C and ATU-R) | +| ERL | Echo return loss | +| ES | Errored second | + +| | | +|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------| +| FDM | Frequency-division multiplexing | +| FEBE | Far-end Block Error | +| FEBE-F | Binary indication of far-end block error count-fast data | +| FEBE-I | Binary indication of far-end block error count-interleaved data | +| FEC | Forward error correction | +| FECC-F | Binary indication of forward error correction count-fast data | +| FECC-I | Binary indication of forward error correction count-interleaved data | +| FEXT | Far-end crosstalk | +| FFEC | Far-end Forward Error Correction | +| FHEC | Far-end Header Error Check | +| FLCD | Far-end Loss of Cell Delineation | +| FNCD | Far-end No Cell Delineation | +| FOCD | Far-end Out of Cell Delineation | +| GF | Galois Field | +| GNTPDN | Grant Power Down | +| GSTN | General switched telephone network | +| HDSL | High bit rate digital subscriber line | +| HEC | Header error control | +| HPF | High pass filter | +| IB | Indicator Bit | +| ib0-23 | Indicator bits | +| ID code | Vendor identification code | +| IDFT | Inverse discrete Fourier transform | +| ISDN | Integrated Services Digital Network | +| $K_F$ | Number of bytes in a downstream (or upstream) fast mux data frame | +| $K_I$ | Number of bytes in a downstream (or upstream) interleaved mux data frame | +| LCD | Loss of Cell Delineation | +| LEX | L(S) Extension byte: byte inserted in the transmitted ADSL frame structure to provide synchronization capacity that is shared among LSx and ASx bearer channels | +| LOF | Loss of frame defect | +| LOS | Loss-of-signal defect | +| LPR | Loss-of-power defect | +| LS0-2 | DUPLEX bearer channel designators | +| LSB | Least significant bit | +| LSx | Any one of the duplex bearer channels LS0-2 | +| LTR | Local timing reference | +| MC | Maximum count indication | +| MSB | Most significant bit | +| MTPR | Multitone power ratio | +| NCD | No cell delineation | +| NEXT | Near-end crosstalk | + +| | | +|-----------|---------------------------------------------------------------------------------------------------------------------------------| +| $N_F$ | Number of bytes in a downstream (or upstream) FEC output-fast data frame | +| $N_I$ | Number of bytes in a downstream (or upstream) FEC output-interleaved data frame | +| NI | Network interface | +| NID | Network interface Device | +| NMS | Network Management System | +| $n_{PCB}$ | Power cut-back index (See 10.4.5.1) | +| NT | Network termination | +| NTR | Network timing reference: 8 kHz reference to be transmitted downstream | +| OAM | Operations, administration and maintenance | +| OCD | Out of Cell Delineation | +| OSS | Operations Support System | +| PHY | Physical Layer | +| PMD/TC | Physical Media Dependent | +| POTS | Plain old telephone service; one of the services using the voiceband; sometimes used as a descriptor for all voiceband services | +| ppm | Parts per million | +| PRBS | Pseudo-random bit sequence | +| PRD | Pseudo-random downstream sequence | +| PRU | Pseudo-random upstream sequence | +| PSD | Power spectral density | +| PSTN | Public switched telephone network | +| QAM | Quadrature amplitude modulation | +| R-B&G | Remote End Bits and Gains Information | +| RDI | Remote Defect Indication | +| REJPDN | Reject Power Down | +| REQPDN | Request Power Down | +| rfi | Remote failure indication | +| $R_F$ | Number of downstream (or upstream) FEC redundancy bytes for fast buffer | +| $R_I$ | Number of downstream (or upstream) FEC redundancy bytes for interleaved buffer | +| rms | Root mean square | +| RRSI | Configuration parameters for FEC and interleaving | +| RS | Reed-Solomon | +| RT | Remote terminal | +| SB | Sync Byte | +| sc0-7 | Synchronization control bit(s) | +| SEF | Severely errored frame | +| SM | Service module | +| SNR | Signal-to-Noise Ratio | +| SONET | Synchronous optical network | +| SPF | Superframe | + +| | | +|----------|-----------------------------------------------------------------------------------------------------| +| SRL | Singing return loss | +| STM | Synchronous transfer mode | +| SWB | Sliding Window Buffer (Annex C) | +| TC | Transmission convergence (sublayer) | +| TCM | Time Compression Multiplex | +| T-R | Interface(s) between ATU-R and switching layer (ATM or STM) | +| T/S | Interface(s) between ADSL network termination and CI or home network | +| TTR | TCM-ISDN Timing Reference (Annex C) | +| Tx | Transmitter | +| U-C | Loop interface-central office end | +| U-R | Loop interface-remote terminal end | +| UTC | Unable to comply | +| V-C | Logical interface between ATU-C and a digital network element such as one or more switching systems | +| ZHP | Impedance high-pass filter | +| 4-QAM | 4-point QAM (i.e. two bits per symbol) | +| $\oplus$ | Exclusive-or; modulo-2 addition | + +## 5 Reference Models + +Figures 5-1 to 5-4 are not requirements or suggestions for building a DMT transmitter. Rather, they are models for facilitating accurate and concise DMT signal waveform descriptions. In the figures $Z_i$ is DMT subcarrier $i$ (defined in the frequency domain), and $x_n$ is the $n$ th IDFT output sample (defined in the time domain). The DAC and analogue processing block of Figures 5-1 to 5-4 construct the continuous transmit voltage waveform corresponding to the discrete digital input samples. More precise specifications for this analogue block arise indirectly from the analogue transmit signal linearity and power spectral density specifications of 7.13 and 7.14. The use of the figures as a transmitter reference model allows all initialization signal waveforms to be described through the sequence of DMT symbols, $\{Z_i\}$ , required to produce that signal. Allowable differences in the characteristics of different digital-to-analogue and analogue processing blocks will produce somewhat different continuous-time voltage waveforms for the same initialization signal. However, a compliant transmitter will produce initialization signals whose underlying DMT subcarrier sequences match exactly those provided in the signal descriptions of 10.4 to 10.9. + +### 5.1 ATU-C transmitter reference models + +ATM and STM are application options. ATU-C and ATU-R may be configured for either STM bit sync transport or ATM cell transport. Hybrid configurations (i.e. some applications run over ATM, some do not, simultaneously) are outside the scope of this Recommendation. + +If the U-C interface is STM bit sync based (i.e. no ATM cells on U-C interface), the ATU-C is configured for STM transport and shall comply to 5.1.1, 6.1 and 7.1. If the U-C interface is ATM cell based (i.e. only ATM cells on U-C interface), the ATU-C is configured for ATM transport and shall comply to 5.1.2, 6.2 and 7.2. + +If the U-R interface is STM bit sync based (i.e. no ATM cells on U-R interface), the ATU-R is configured for STM transport and shall comply to 5.2.1, 6.1 and 8.1. If the U-R interface is ATM cell based (i.e. only ATM cells on U-R interface), the ATU-R is configured for ATM transport and shall comply to 5.2.2, 6.2 and 8.2. + +### 5.1.1 ATU-C transmitter reference model for STM transport + +Figure 5-1 is a block diagram of an ADSL Transceiver Unit-Central office (ATU-C) transmitter showing the functional blocks and interfaces that are referenced in this Recommendation for the downstream transport of STM data. + +![Block diagram of an ATU-C transmitter reference model for STM transport. The diagram shows data flow from multiple input interfaces (AS0-AS3, LS0-LS2, NTR, OAM, V-C, EOC/AOC) through a Mux/Sync Control block. From there, data splits into two paths: one with 'crcf', 'scrambler & FEC', and 'Tone ordering'; the other with 'crci', 'scrambler & FEC', 'Interleaver', and 'Tone ordering'. Both paths converge at 'Tone ordering', which also receives 'bits' input. The output goes to 'Constellation encoder and gain scaling' (receiving 'Bits' & 'Gains'), then to 'IDFT'. The IDFT output (indices 511, 510, 480, 1, n=0) goes to 'Output Parallel/Serial Buffer', which then connects to 'DAC and Analogue processing'. Reference points A, B, and C are marked along the data flow. A label 'T1532330-99' is in the bottom right.](366a77fdefb0097b3289b4a011911390_img.jpg) + +``` + +graph LR + subgraph Inputs + AS0 --> Mux + AS1 --> Mux + AS2 --> Mux + AS3 --> Mux + LS0 --> Mux + LS1 --> Mux + LS2 --> Mux + NTR -.-> Mux + OAM <--> Mux + VC --> Mux + EOC --> Mux + ib --> Mux + end + Mux[Mux/Sync Control] --> crcf[crcf] + Mux --> crci[crci] + crcf --> sfec1[scrambler & FEC] + crci --> sfec2[scrambler & FEC] + sfec1 --> Tone[Tone ordering] + sfec2 --> Int[Interleaver] + Int --> Tone + bits[bits] --> Tone + Tone --> Const[Constellation encoder and gain scaling] + BG[Bits & Gains] --> Const + Const --> IDFT[IDFT] + IDFT --> Buff[Output Parallel/Serial Buffer] + Buff --> DAC[DAC and Analogue processing] + +``` + +Block diagram of an ATU-C transmitter reference model for STM transport. The diagram shows data flow from multiple input interfaces (AS0-AS3, LS0-LS2, NTR, OAM, V-C, EOC/AOC) through a Mux/Sync Control block. From there, data splits into two paths: one with 'crcf', 'scrambler & FEC', and 'Tone ordering'; the other with 'crci', 'scrambler & FEC', 'Interleaver', and 'Tone ordering'. Both paths converge at 'Tone ordering', which also receives 'bits' input. The output goes to 'Constellation encoder and gain scaling' (receiving 'Bits' & 'Gains'), then to 'IDFT'. The IDFT output (indices 511, 510, 480, 1, n=0) goes to 'Output Parallel/Serial Buffer', which then connects to 'DAC and Analogue processing'. Reference points A, B, and C are marked along the data flow. A label 'T1532330-99' is in the bottom right. + +NOTE – Solid versus dashed lines are used to indicate required versus optional capabilities respectively. This figure is not intended to be complete in this respect, see clauses 6 and 7 for specific details. + +**Figure 5-1/G.992.1 – ATU-C transmitter reference model for STM transport** + +Support of STM is optional; if it is provided, however, the following requirements shall be met: + +- The basic STM transport mode is bit serial. +- The framing mode used determines if byte boundaries, if present at the V-C interface, shall be preserved. +- Outside the ASx/LSx serial interfaces data bytes are transmitted MSB first. All serial processing in the ADSL frame (e.g. CRC, scrambling, etc.) shall, however, be performed LSB first, with the outside world MSB considered by the ADSL as LSB. As a result, the first incoming bit (outside world MSB) shall be the first processed bit inside the ADSL (ADSL LSB). +- ADSL equipment shall support at least bearer channels AS0 and LS0 downstream as defined in 6.1. Support of other bearer channels is optional. +- Two paths are shown between the Mux/Sync control and Tone ordering; the "fast" path provides low latency; the interleaved path provides very low error rate and greater latency. The allocation of user data at the V-C interface to these paths is defined in 7.4. An ADSL system supporting STM shall be capable of operating in a dual latency mode for the downstream direction, in which user data is allocated to both paths (i.e. fast and interleaved), and a single latency mode for both the downstream and upstream directions, in which all user data is allocated to one path (i.e. fast or interleaved). An ADSL system supporting STM transport may be capable of operating in an optional dual latency mode for the upstream, in which user data is allocated to both paths (i.e. fast and interleaved). + +### 5.1.2 ATU-C transmitter reference model for ATM transport + +Figure 5-2 is a block diagram of an ADSL Transceiver Unit-Central office (ATU-C) transmitter showing the functional blocks and interfaces that are referenced in this Recommendation for the downstream transport of ATM data. + +![Figure 5-2/G.992.1 – ATU-C transmitter reference model for ATM transport](552265bdbcf6d43d341fd018a9076269_img.jpg) + +The diagram illustrates the functional blocks of an ATU-C transmitter. Inputs include ATM0, ATM1, NTR, OAM, V-C, and EOC/AOC ib. These feed into a 'Mux/Sync Control' block. From there, two paths emerge: a 'fast' path (top) and an 'interleaved' path (bottom). The fast path includes AS0, Cell TC, crcf, and a 'scrambler & FEC' block. The interleaved path includes AS1, Cell TC, crci, 'scrambler & FEC', and an 'Interleaver'. Both paths lead to a 'Tone ordering' block, which also receives 'Bits' and 'Bits & Gains' inputs. This is followed by 'Constellation encoder and gain scaling', which outputs Zi (i=1 to 255). The signal then passes through an 'IDFT' block (with indices 511, 510, 480, 1, n=0) and an 'Output Parallel/Serial Buffer'. The final stage is 'DAC and Analogue processing'. Reference points A (Mux Data Frame), B (FEC Output Data Frame), and C (Constellation Encoder Input Data Frame) are marked along the bottom. + +Figure 5-2/G.992.1 – ATU-C transmitter reference model for ATM transport + +NOTE – Solid versus dashed lines are used to indicate required versus optional capabilities respectively. This figure is not intended to be complete in this respect, see clauses 6 and 7 for specific details. + +**Figure 5-2/G.992.1 – ATU-C transmitter reference model for ATM transport** + +Support of ATM is optional; if it is provided, however, the following requirements shall be met: + +- Byte boundaries at the V-C interface shall be preserved in the ADSL data frame. +- Outside the ASx/LSx serial interfaces data bytes are transmitted MSB first. All serial processing in the ADSL frame (e.g. CRC, scrambling, etc.) shall, however, be performed LSB first, with the outside world MSB considered by the ADSL as LSB. As a result, the first incoming bit (outside world MSB) will be the first processed bit inside the ADSL (ADSL LSB), and the CLP bit of the ATM cell header will be carried in the MSB of the ADSL frame byte (i.e. processed last). +- ADSL equipment shall support at least bearer channel AS0 downstream as defined in 6.2. Support of other bearer channels is optional. +- Two paths are shown between the Mux/Sync control and Tone ordering; the "fast" path provides low latency; the interleaved path provides very low error rate and greater latency. The allocation of user data at the V-C interface to these paths is defined in clause 7. An ADSL system supporting ATM transport shall be capable of operating in a single latency mode, in which all user data is allocated to one path (i.e. fast or interleaved). An ADSL system supporting ATM transport may be capable of operating in an optional dual latency mode, in which user data is allocated to both paths (i.e. fast and interleaved). + +## 5.2 ATU-R transmitter reference models + +### 5.2.1 ATU-R transmitter reference model for STM transport + +Figure 5-3 is a block diagram of an ATU-R transmitter showing the functional blocks and interfaces that are referenced in this Recommendation for the upstream transport of STM data. + +![Block diagram of an ATU-R transmitter reference model for STM transport. The diagram shows data flow from multiple input interfaces (LS0, LS1, LS2, T-R) through a Mux/Sync Control block. From there, two paths are shown: a 'fast' path (crc_f, scrambler & FEC) and an 'interleaved' path (crc_i, scrambler & FEC, Interleaver). Both paths lead to a Tone ordering block. External inputs 'Bits' and 'Bits' & 'Gains' also feed into the Tone ordering block. The output of Tone ordering goes to a Constellation encoder and gain scaling block, which then feeds into an IDFT block. The IDFT block has 64 outputs (0 to 63), with outputs 1 to 63 being processed by an Output Parallel/Serial Buffer. Output 0 is processed by a DAC and Analogue processing block. Reference points A, B, C, and Z_i are marked along the data flow. A note at the bottom right indicates 'T1532350-99'.](90ddb84c323b956e2d50a54d3f870566_img.jpg) + +``` + +graph LR + LS0_in[LS0] --> Mux[Mux/Sync Control] + LS1_in[LS1] --> Mux + LS2_in[LS2] --> Mux + TR_in[T-R] --> Mux + EOC_AOC[EOC/AOC] --> Mux + + Mux --> crc_f[crcf] + crc_f --> scram_f[scrambler & FEC] + scram_f --> Tone[Tone ordering] + + Mux --> crc_i[crci] + crc_i --> scram_i[scrambler & FEC] + scram_i --> Inter[Interleaver] + Inter --> Tone + + Bits[Bits] --> Tone + BitsGains[Bits & Gains] --> Const[Constellation encoder and gain scaling] + + Tone --> Const + Const --> IDFT[IDFT] + + IDFT --> OutBuf[Output Parallel/Serial Buffer] + IDFT --> DAC[DAC and Analogue processing] + + subgraph Reference_Points + A[A Mux Data Frame] + B[B FEC Output Data Frame] + C[C Constellation Encoder Input Data Frame] + Zi[Zi i=1 to 31] + end + +``` + +Block diagram of an ATU-R transmitter reference model for STM transport. The diagram shows data flow from multiple input interfaces (LS0, LS1, LS2, T-R) through a Mux/Sync Control block. From there, two paths are shown: a 'fast' path (crc\_f, scrambler & FEC) and an 'interleaved' path (crc\_i, scrambler & FEC, Interleaver). Both paths lead to a Tone ordering block. External inputs 'Bits' and 'Bits' & 'Gains' also feed into the Tone ordering block. The output of Tone ordering goes to a Constellation encoder and gain scaling block, which then feeds into an IDFT block. The IDFT block has 64 outputs (0 to 63), with outputs 1 to 63 being processed by an Output Parallel/Serial Buffer. Output 0 is processed by a DAC and Analogue processing block. Reference points A, B, C, and Z\_i are marked along the data flow. A note at the bottom right indicates 'T1532350-99'. + +NOTE – Solid versus dashed lines are used to indicate required versus optional capabilities respectively. This figure is not intended to be complete in this respect, see clauses 6 and 8 for specific details. + +**Figure 5-3/G.992.1 – ATU-R transmitter reference model for STM transport** + +Support of STM is optional; if it is provided, however, the following requirements shall be met: + +- The basic STM transport mode is bit serial. +- The framing mode used determines if byte boundaries, if present at the T-R interface, shall be preserved. +- Outside the LSx serial interfaces data bytes are MSB transmitted first. All serial processing in the ADSL frame (e.g. CRC, scrambling, etc.) shall, however, be performed LSB first, with the outside world MSB considered by the ADSL as LSB. As a result, the first incoming bit (outside world MSB) will be the first processed bit inside the ADSL (ADSL LSB). +- ADSL equipment shall support at least bearer channel LS0 upstream as defined in 6.1. Support of other bearer channels is optional. +- Two paths are shown between the Mux/Sync control and Tone ordering; the "fast" path provides low latency; the interleaved path provides very low error rate and greater latency. The allocation of user data at the T-R interface to these paths is defined in 8.4. An ADSL system supporting STM shall be capable of operating in a dual latency mode for the downstream direction, in which user data is allocated to both paths (i.e. fast and interleaved), and a single latency mode for both the downstream and upstream directions, in which all user data is allocated to one path (i.e. fast or interleaved). An ADSL system supporting STM transport may be capable of operating in an optional dual latency mode for the upstream, in which user data is allocated to both paths (i.e. fast and interleaved). + +## 5.2.2 ATU-R transmitter reference model for ATM transport + +Figure 5-4 is a block diagram of an ATU-R transmitter showing the functional blocks and interfaces that are referenced in this Recommendation for the upstream transport of ATM data. + +![Figure 5-4: ATU-R transmitter reference model for ATM transport block diagram.](a149b400127a3e3e50b3c98d27c5935c_img.jpg) + +The diagram illustrates the functional flow of an ATU-R transmitter. It starts with two ATM inputs, ATM0 and ATM1, which pass through 'Cell TC' blocks to become LS0 and LS1 signals. These enter a 'Mux/Sync Control' block, which also receives inputs from 'EOC/AOC' and a 'T-R' interface. The output of the Mux/Sync Control splits into two paths: a 'fast' path and an 'interleaved' path. The fast path consists of $crc_f$ and 'scrambler & FEC' blocks. The interleaved path consists of $crc_i$ , 'scrambler & FEC', and an 'Interleaver' block. Both paths lead into a 'Tone ordering' block (marked with 'Bits' and 'Bits & Gains' inputs). This is followed by a 'Constellation encoder and gain scaling' block, outputting $Z_i$ for $i=1$ to 31. These signals enter an 'IDFT' block (with outputs labeled 63, 62, 60, 1, and $n=0$ ), which feeds into an 'Output Parallel/Serial Buffer'. Finally, the signal goes to 'DAC and Analogue processing'. Reference points A (Mux Data Frame), B (FEC Output Data Frame), and C (Constellation Encoder Input Data Frame) are indicated along the bottom. Solid lines indicate required capabilities, while dashed lines indicate optional ones. + +Figure 5-4: ATU-R transmitter reference model for ATM transport block diagram. + +NOTE – Solid versus dashed lines are used to indicate required versus optional capabilities respectively. This figure is not intended to be complete in this respect, see clauses 6 and 8 for specific details. + +**Figure 5-4/G.992.1 – ATU-R transmitter reference model for ATM transport** + +Support of ATM is optional; if it is provided, however, the following requirements shall be met: + +- Byte boundaries at the T-R interface shall be preserved in the ADSL data frame. +- Outside the LSx serial interfaces data bytes are transmitted MSB first in accordance with Recommendations I.361 and I.432.1. All serial processing in the ADSL frame (e.g. CRC, scrambling, etc.) shall, however, be performed LSB first, with the outside world MSB considered by the ADSL as LSB. As a result, the first incoming bit (outside world MSB) will be the first processed bit inside the ADSL (ADSL LSB), and the CLP bit of the ATM cell header will be carried in the MSB of the ADSL frame byte (i.e. processed last). +- ADSL equipment shall support at least bearer channel LS0 upstream as defined in 6.2. Support of other bearer channels is optional. +- Two paths are shown between the Mux/Sync control and Tone ordering; the "fast" path provides low latency; the interleaved path provides very low error rate and greater latency. The allocation of user data at the T-R interface to these paths is defined in 8.4. An ADSL system supporting ATM transport shall be capable of operating in a single latency mode, in which all user data is allocated to one path (i.e. fast or interleaved). An ADSL system supporting ATM transport may be capable of operating in an optional dual latency mode, in which user data is allocated to both paths (i.e. fast and interleaved). + +## 5.3 ATU-C/R transmitter timing model (Annex C only) + +For Annex C, see C.3.3. + +**6 Transport capacity** + +An ADSL system may transport up to seven user data streams on seven bearer channels simultaneously: + +- up to four independent downstream simplex bearers [unidirectional from the network operator (i.e. V-C interface) to the CI (i.e. T-R interface)]; +- up to three duplex bearers (bidirectional between the network operator and the CI). + +The three duplex bearers may alternatively be configured as independent unidirectional simplex bearers, and the rates of the bearers in the two directions (network operator toward CI and vice versa) do not need to match. + +All bearer channel data rates shall be programmable in any combination of integer multiples of 32 kbit/s. The ADSL data multiplexing format is flexible enough to allow other transport data rates, such as channelizations based on existing 1.544 Mbit/s, but the support of these data rates (non-integer multiples of 32 kbit/s) will be limited by the ADSL system's available capacity for synchronization (see Notes 1 and 2). + +The maximum net data rate transport capacity of an ADSL system will depend on the characteristics of the loop on which the system is deployed, and on certain configurable options that affect overhead (see Note 3). The ADSL bearer channel rates shall be configured during the initialization and training procedure. + +The transport capacity of an ADSL system per se is defined only as that of the bearer channels. When, however, an ADSL system is installed on a line that also carries POTS or ISDN signals, the overall capacity is that of POTS or ISDN plus ADSL. + +A distinction is made between the transport of synchronous (STM) and asynchronous (ATM) data. An ATU-x shall be configured to support STM transmission or ATM transmission. If STM is supported, it shall be as defined in 6.1 and either 7.1 (ATU-C) or 8.1 (ATU-R). If ATM is supported, it shall be as defined in 6.2 and either 7.2 (ATU-C) or 8.2 (ATU-R). Bearer channels configured to transport STM data can also be configured to carry ATM data. ADSL equipment may be capable of simultaneously supporting both ATM and STM transport, but is otherwise outside the scope of this Recommendation. + +If an ATU-x supports a particular bearer channel, it shall support it through both the fast and interleaved paths. + +In addition, an ADSL system may transport a Network Timing Reference (NTR). The means for doing this are specified in 7.2.4. + +NOTE 1 – Part of the ADSL system overhead is shared among the bearer channels for synchronization. The remainder of each channel's data rate that exceeds a multiple of 32 kbit/s is transported in this shared overhead. Only framing mode 0 supports non-integer multiples of 32 kbit/s. + +NOTE 2 – The rates for all bearer channels are based on integer multiples of 32 kbit/s. ADSL deployments may, however, need to interwork with DS1 (1.544 Mbit/s) data. The ADSL system overhead and data synchronization (see 6.4.2) provide enough capacity to support the framed DS1 data streams transparently (i.e. the entire DS1 signal is passed through the ADSL transmission path without interpretation or removal of the framing bits and other overhead). + +NOTE 3 – One part of the ADSL initialization and training sequence estimates the loop characteristics to determine whether the number of bytes per Discrete MultiTone (DMT) frame required for the requested configuration's aggregate data rate can be transmitted across the given loop. The net data rate is then the aggregate data rate minus ADSL system overhead. Part of the ADSL system overhead is dependent on the configurable options, such as allocation of bearer channels to interleaving or non-interleaving data buffers within the ADSL frame (discussed in 7.4 and 8.4), and part of it is fixed. + +NOTE 4 – The latency mode of an ADSL system may be different for downstream and upstream transmission. + +## 6.1 Transport of STM data + +ADSL systems transporting STM shall support the simplex bearer channel AS0 and the duplex bearer channel LS0 downstream; support of AS1, AS2, AS3, LS1 and LS2 is optional. Bearer channels AS0, LS0, and any other bearer channels supported shall be independently allocable to a particular latency path as selected by the ATU-C at start-up. The system shall support dual-latency downstream. + +ADSL systems transporting STM shall support the duplex bearer channel LS0 upstream using a single latency path; support of LS1 and LS2 and dual latency is optional. + +Bearer channel AS0 shall support the transport of data at all integer multiples of 32 kbit/s from 32 kbit/s to 6.144 Mbit/s. Bearer channel LS0 shall support 16 kbit/s and all integer multiples of 32 kbit/s from 32 kbit/s to 640 kbit/s. + +When AS1, AS2, AS3, LS1 and LS2 are provided, they shall support the range of integer multiples of 32 kbit/s shown in Table 6-1. Support for integer multiples beyond those required and indicated therein is optional. Further, support for data rates based on non-integer multiples of 32 kbit/s is also optional. + +**Table 6-1/G.992.1 – Required 32 kbit/s integer multiples for transport of STM** + +| Bearer channel | Lowest Required Integer Multiple | Largest Required Integer Multiple | Corresponding Highest Required Data Rate (kbit/s) | +|----------------|----------------------------------|-----------------------------------|---------------------------------------------------| +| AS0 | 1 | 192 | 6144 | +| AS1 | 1 | 144 | 4608 | +| AS2 | 1 | 96 | 3072 | +| AS3 | 1 | 48 | 1536 | +| LS0 | 1 | 20 | 640 | +| LS1 | 1 | 20 | 640 | +| LS2 | 1 | 20 | 640 | + +Table 6-2 illustrates the data rate terminology and definitions used for STM transport. The reference points refer to those shown in Figures 5-1 through 5-4. + +**Table 6-2/G.992.1 – Data Rate Terminology for STM transport** + +| Data Rate | Equation (kbit/s) | Reference Point | +|--------------------------------------------------------------------------------|--------------------------------------|-----------------| +| STM data rate = "Net data rate" | $\sum(B_I, B_F) \times 32$
(Note) | ASx + LSx | +| "Net data rate" + Frame overhead rate = "Aggregate data rate" | $\sum(K_I, K_F) \times 32$ | A | +| "Aggregate data rate" + RS Coding overhead rate = "Total data rate" | $\sum(N_I, N_F) \times 32$ | B | +| "Total data rate" + Trellis Coding overhead rate = Line rate | $\sum b_i \times 4$ | U | +| NOTE – Net data rate increase by 16 kbit/s if a 16 kbit/s "C"-channel is used. | | | + +## 6.2 Transport of ATM data + +An ADSL system transporting ATM shall support the single latency mode (Note 1) at all integer multiples of 32 kbit/s up to 6.144 Mbit/s downstream and up to 640 kbit/s upstream. For single latency, ATM data shall be mapped to bearer channel AS0 in the downstream direction and to bearer channel LS0 in the upstream direction. Single latency is defined as all payload data passing through a single latency path. It is important to note that with framing modes 0,1 and 2, overhead data exists in both latency paths even though the payload is allocated to a single latency path. + +The need for dual latency for ATM services depends on the service/application profile and is under study. One of three different "latency classes" may be used via: + +- single latency, not necessarily the same for each direction of transmission; +- dual latency downstream, single latency upstream; +- dual latency both upstream and downstream. + +ADSL systems transporting ATM shall support bearer channel AS0 downstream and bearer channel LS0 upstream, with each of these bearer channels independently allocable to a particular latency path as selected by the ATU-C at start-up. Therefore, support of dual latency is optional for both downstream and upstream. + +If downstream ATM data are transmitted through a single latency path (i.e. "fast" only or "interleaved" only), only bearer channel AS0 shall be used, and it shall be allocated to the appropriate latency path. If downstream ATM data are transmitted through both latency paths (i.e. "fast" and "interleaved"), only bearer channels AS0 and AS1 shall be used, and they shall be allocated to different latency paths. + +Similarly, if upstream ATM data are transmitted through a single latency path (i.e. "fast" only or "interleaved" only), only bearer channel LS0 shall be used and it shall be allocated to the appropriate latency path. The choice of the fast or interleaved path may be made independently of the choice for the downstream data. If upstream ATM data are transmitted through both latency paths (i.e. "fast" and "interleaved"), only bearer channels LS0 and LS1 shall be used and they shall be allocated to different latency paths. + +Bearer channel AS0 shall support the transport of data at all integer multiples of 32 kbit/s from 32 kbit/s to 6.144 Mbit/s. Bearer channel LS0 shall support all integer multiples of 32 kbit/s from 32 kbit/s to 640 kbit/s. Support for data rates based on non-integer multiples of 32 kbit/s is also optional. + +When AS1 and LS1 are provided, they shall support the range of integer multiples of 32 kbit/s shown in Table 6-1. Support for integer multiples beyond those required and indicated in Table 6-1 is optional. Further, support for data rates based on non-integer multiples of 32 kbit/s is also optional. + +Bearer channels AS2, AS3 and LS2 shall not be provided for an ATM based ATU-x. + +NOTE 1 – For ATM systems, the channelization of different payloads is embedded within the ATM data stream using different Virtual Paths and/or Virtual Channels. Therefore the basic requirements for ATM are for only one ADSL bearer channel downstream and only one ADSL bearer channel upstream. + +NOTE 2 – More details of the ATM to Physical layer logical interface are given in Appendix I. + +Table 6-3 illustrates the data rate terminology and definitions used for ATM transport. The reference points refer to those shown in Figures 5-1 through 5-4. + +**Table 6-3/G.992.1 – Data rate terminology for ATM transport** + +| Data Rate | Equation (kbit/s) | Reference Point | +|--------------------------------------------------------------------------------------------------------------|----------------------------|------------------------| +| $53 \times 8 \times \text{ATM cell rate} \quad = \quad \text{"Net data rate"}$ | $\sum(B_I, B_F) \times 32$ | ASx + LSx | +| $\text{"Net data rate"} \quad + \text{Frame overhead rate} \quad = \quad \text{"Aggregate data rate"}$ | $\sum(K_I, K_F) \times 32$ | A | +| $\text{"Aggregate data rate"} \quad + \text{RS Coding overhead rate} \quad = \quad \text{"Total data rate"}$ | $\sum(N_I, N_F) \times 32$ | B | +| $\text{"Total data rate"} \quad + \text{Trellis Coding overhead rate} \quad = \quad \text{Line rate}$ | $\sum b_i \times 4$ | U | + +### **6.3 ADSL system overheads and total bit rates** + +The total bit rate transmitted by the ADSL system when operating in an optional reduced-overhead framing mode shall include capacity for: + +- the data rate transmitted in the ADSL bearer channels; +- ADSL system overhead, which includes: + - an ADSL embedded operations channel, EOC; + - an ADSL overhead control channel, AOC; + - CRC check bytes; + - fixed indicator bits for OAM; + - FEC redundancy bytes. + +When operating in the full-overhead mode, the total bit rate shall also include capacity for the synchronization control bytes and capacity for bearer channel synchronization control. + +The above data streams shall be organized into ADSL frames and superframes as defined in 7.4 and 8.4 for the downstream and upstream data, respectively. + +The internal overhead channels and their rates are shown in Table 6-4. + +**Table 6-4/G.992.1 – Internal overhead channel functions and rates** + +| | Downstream rate (kbit/s)
minimum/maximum | | Upstream rate (kbit/s)
minimum/maximum | | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------|------------------------------------------------------|---------------------------------------------------------|------------------------------------------------------| +| | Number of
ASx bearer
channels
> 1 | Number of
ASx bearer
channels
= 1 | Number of
LSx bearer
channels
> 1 | Number of
LSx bearer
channels
= 1 | +| Synchronization control, CRC and AOC; interleaved buffer | 32/32 | 32/32 | 32/32 | 32/32 | +| Synchronization control, CRC, EOC and indicator bits; fast buffer | 32/32 | 32/32 | 32/32 | 32/32 | +| Total for reduced overhead framing | 32/64
(Note 2) | 32/64
(Note 2) | 32/64
(Note 2) | 32/64
(Note 2) | +| Synchronization capacity
(shared among all bearer channels) | 64/128
(Note 3) | 64/96
(Note 3) | 32/64
(Note 3) | 32/32
(Note 3) | +| Total
(Note 1) | 128/192 | 128/160 | 96/128 | 96/96 | +|

NOTE 1 – The overhead required for FEC is not shown in this table.

NOTE 2 – With the reduced overhead framing modes, a 32 kbit/s ADSL system overhead is present in each buffer type. However, when all ASx and LSx are allocated to one buffer type, synchronization control, CRC, EOC, AOC and indicator bits may be carried in a single 32 kbit/s ADSL system overhead present in the buffer type used. With full overhead framing, a 32 kbit/s ADSL system overhead is always present in each buffer type.

NOTE 3 – The shared synchronization capacity includes 32 kbit/s shared among LSx within the interleave buffer, 32 kbit/s shared among LSx within the fast buffer, 32 kbit/s shared among ASx within the interleave buffer, and 32 kbit/s shared among ASx within the fast buffer. The maximum rate occurs when at least one ASx is allocated to each type of buffer; the minimum rate occurs when all ASx and LSx are allocated to one buffer type.

| | | | | + +### 7 ATU-C functional characteristics + +An ATU-C may support STM transmission or ATM transmission or both. If STM is supported it shall be as defined in 7.1. If ATM is supported it shall be as defined in 7.2. + +Framing modes that shall be supported depend upon the ATU-C being configured for either STM or ATM transport, and are defined in 7.1.5 and 7.2.4 respectively. If framing mode k is supported, then modes k-1, ..., 0 shall also be supported. + +During initialization, the ATU-C and ATU-R shall indicate a framing mode number 0, 1, 2 or 3 which they intend to use. The lowest indicated framing mode shall be used (see 10.6.4 and 10.7.6). + +Using framing mode 0 ensures that an STM based ATU-x with an external ATM TC will interoperate with an ATM based ATU-x. Additional modes of interoperation are possible depending upon optional features provided in either ATU-x. + +An ATU-C may provide a Network Timing Reference (NTR). This operation shall be independent of any clocking that is internal to the ADSL system. If provided, the NTR shall be inserted in the U-C framing structure as described in 7.3.2. + +## 7.1 STM Transmission Protocol Specific functionalities + +### 7.1.1 ATU-C input and output V interfaces for STM transport + +The functional data interfaces at the ATU-C for STM transport are shown in Figure 7-1. Input interfaces for the high-speed downstream simplex bearer channels are designated AS0 through AS3; input/output interfaces for the duplex bearer channels are designated LS0 through LS2. There shall also be a duplex interface for operations, administration, maintenance (OAM) and control of the ADSL system. + +The data rates of the input and output data interfaces at the ATU-C are specified in 6.1. The data rate at a given interface shall match the rate of the bearer channel configured to that interface. + +![Diagram of ATU-C functional interfaces for STM transport at the V-C reference point.](3e2a8dc8c5537dbe703cdcb0e21e4e1b_img.jpg) + +The diagram illustrates the functional interfaces between the STM Layer and the ATU-C at the V-C reference point. On the left, a box represents the 'STM Layer and interface to Digital Network'. On the right, a box represents the 'ATU-C', which is connected to a 'twisted pair' on its right side. A vertical dashed line labeled 'V-C' at the bottom separates the two main components. The interfaces are as follows: + +- AS0 ( $n_0 \times 32$ kbit/s): A solid line with an arrow pointing from the STM Layer to the ATU-C. +- AS1 ( $n_1 \times 32$ kbit/s): A dotted line with an arrow pointing from the STM Layer to the ATU-C. +- AS2 ( $n_2 \times 32$ kbit/s): A dotted line with an arrow pointing from the STM Layer to the ATU-C. +- AS3 ( $n_3 \times 32$ kbit/s): A dotted line with an arrow pointing from the STM Layer to the ATU-C. +- LS0 ("C"; 16 or $m_0 \times 32$ kbit/s): A solid line with arrows pointing in both directions between the STM Layer and the ATU-C. +- LS1 ( $m_1 \times 32$ kbit/s): A dotted line with arrows pointing in both directions between the STM Layer and the ATU-C. +- LS2 ( $m_2 \times 32$ kbit/s): A dotted line with arrows pointing in both directions between the STM Layer and the ATU-C. +- NTR: A dotted line with an arrow pointing from the STM Layer to the ATU-C. +- Operations, administration, maintenance and control: A solid line with arrows pointing in both directions between the STM Layer and the ATU-C. + +T1532370-99 + +Diagram of ATU-C functional interfaces for STM transport at the V-C reference point. + +NOTE – Optional bearer channels (both duplex and simplex) and features are shown with dotted lines. + +**Figure 7-1/G.992.1 – ATU-C functional interfaces for STM transport at the V-C reference point** + +### 7.1.2 Downstream simplex channels – bit rates + +Four data input interfaces are defined at the ATU-C for the high-speed downstream simplex channels: AS0, AS1, AS2 and AS3 (ASx in general). The required data rate configurations are specified in 6.1. + +### 7.1.3 Downstream/upstream duplex channels – bit rates + +Three input and output data interfaces are defined at the ATU-C for the duplex channels supported by the ADSL system; LS0, LS1, and LS2 (LSx in general). The required data rate configurations are specified in 6.1. + +LS0 is also known as the "C" or control channel. It carries the signalling associated with the ASx bearer channels and it may also carry some or all of the signalling associated with the other duplex bearer channels. + +### 7.1.4 Payload transfer delay + +The one-way transfer delay for payload bits in all bearers (simplex and duplex) from the V reference point at central office end (V-C) to the T reference point at remote end (T-R) for channels assigned to the fast buffer shall be no more than 2 ms, and for channels assigned to the interleave buffer it shall be no more than $(4 + (S - 1)/4 + S imes D/4)$ ms, where $S$ and $D$ are defined in 7.6. The same requirement applies in the opposite direction, from the T-R reference point to the V-C reference point. + +### 7.1.5 Framing Structure for STM transport + +An ATU-C configured for STM transport shall support the full overhead framing structure 0 as specified in 7.4. The support of full overhead framing structure 1 and the reduced overhead framing structures 2 and 3 is optional. + +Preservation of V-C interface byte boundaries (if present) at the U-C interface may be supported for any of the U-C interface framing structures. + +An ATU-C configured for STM transport may support insertion of a Network Timing Reference (NTR). If inserted, the NTR shall be inserted in the U-C framing structure as described in 7.3.2. + +## 7.2 ATM Transport Protocol Specific functionalities + +### 7.2.1 ATU-C input and output V interface for ATM transport + +The functional data interfaces at the ATU-C for ATM are shown in Figure 7-2. The ATM channel ATM0 shall always be provided, the channel ATM1 is optional and may be provided for support of dual latency mode. Each channel operates as an interface to a physical layer pipe. When operating in dual latency mode, no fixed allocation between the ATM channels 0 and 1, on one hand, and transport of "fast" and "interleaved" data, on the other hand, is assumed. This relationship is configured inside the ATU-C. + +Flow control functionality shall be available on the V reference point to allow the ATU-C (i.e. the physical layer) to control the cell flow to and from the ATM layer. This functionality is represented by Tx\_Cell\_Handshake and Rx\_Cell\_Handshake. A cell may be transferred from ATM to PHY layer only after the ATU-C has activated the Tx\_Cell\_Handshake. Similarly a cell may be transferred from the PHY layer to the ATM layer only after the Rx\_Cell\_Handshake. This functionality is important to avoid cell overflow or underflow in the ATU-C and ATM layers. + +There shall also be a duplex interface for operations, administration, maintenance (OAM) and control of the ADSL system. + +![Diagram of ATU-C functional interfaces to the ATM layer at the V-C reference point. The diagram shows the internal structure of an ATU-C, including the ATM layer, Digital Network, and two ATM channels (ATM0 and ATM1). The ATM layer contains a PORT 0 and a PORT 1. PORT 0 is connected to the Digital Network and the ATM0 channel. PORT 1 is connected to the Digital Network and the ATM1 channel. The ATM0 channel contains Tx_ATM0, Tx_Cell_Handshake0, Rx_ATM0, and Rx_Cell_Handshake0. The ATM1 channel contains Tx_ATM1, Tx_Cell_Handshake1, Rx_ATM1, and Rx_Cell_Handshake1. The NTR (Network Termination Reference) is shown between the Digital Network and the ATU-C. The Operations, administration, maintenance and control (OAM) is shown between the Digital Network and the ATU-C. The V-C reference point is indicated by a vertical dashed line.](f9c64800d9bace9b4315646d1057be3c_img.jpg) + +The diagram illustrates the functional interfaces of an ATU-C to the ATM layer at the V-C reference point. On the left, the 'Digital Network' connects to the 'ATM layer'. The ATM layer contains two ports: 'PORT 0' and 'PORT 1'. PORT 0 is connected to the 'ATM0' channel, and PORT 1 is connected to the 'ATM1' channel. Both ports are also connected to a central switching element (represented by an 'X'). The 'ATM0' channel contains four interfaces: 'Tx\_ATM0', 'Tx\_Cell\_Handshake0', 'Rx\_ATM0', and 'Rx\_Cell\_Handshake0'. The 'ATM1' channel contains four interfaces: 'Tx\_ATM1', 'Tx\_Cell\_Handshake1', 'Rx\_ATM1', and 'Rx\_Cell\_Handshake1'. All these interfaces connect to the 'ATU-C' on the right. Below the ATM channels, the 'NTR' (Network Termination Reference) and 'Operations, administration, maintenance and control' interfaces are shown between the Digital Network and the ATU-C. A vertical dashed line labeled 'V-C' marks the reference point between the Digital Network and the ATU-C. The text 'T1532380-99' is in the bottom right corner. + +Diagram of ATU-C functional interfaces to the ATM layer at the V-C reference point. The diagram shows the internal structure of an ATU-C, including the ATM layer, Digital Network, and two ATM channels (ATM0 and ATM1). The ATM layer contains a PORT 0 and a PORT 1. PORT 0 is connected to the Digital Network and the ATM0 channel. PORT 1 is connected to the Digital Network and the ATM1 channel. The ATM0 channel contains Tx\_ATM0, Tx\_Cell\_Handshake0, Rx\_ATM0, and Rx\_Cell\_Handshake0. The ATM1 channel contains Tx\_ATM1, Tx\_Cell\_Handshake1, Rx\_ATM1, and Rx\_Cell\_Handshake1. The NTR (Network Termination Reference) is shown between the Digital Network and the ATU-C. The Operations, administration, maintenance and control (OAM) is shown between the Digital Network and the ATU-C. The V-C reference point is indicated by a vertical dashed line. + +**Figure 7-2/G.992.1 – ATU-C functional interfaces to the ATM layer at the V-C reference point** + +## 7.2.2 Payload transfer delay + +The one-way transfer delay (excluding cell specific functionalities) for payload bits in all bearers (simplex and duplex) from the V reference point at central office end (V-C) to the T reference point at remote end (T-R) for channels assigned to the fast buffer shall be no more than 2 ms, and for channels assigned to the interleave buffer it shall be no more than $(4 + (S - 1)/4 + S \times D/4)$ ms, where $S$ and $D$ are defined in 7.6. The same requirement applies in the opposite direction, from the T-R reference point to the V-C reference point. + +NOTE – The additional delay introduced by the cell specific functionalities is implementation specific. + +## 7.2.3 ATM Cell specific functionalities + +### 7.2.3.1 Idle Cell Insertion + +Idle cells shall be inserted in the transmit direction for cell rate decoupling. Idle cells are identified by the standardized pattern for the cell header given in Recommendation I.432.1. + +NOTE – This Recommendation is written on the assumption that idle cells will be discarded by an ATU-R receiver. + +### 7.2.3.2 Header Error Control (HEC) Generation + +The HEC byte shall be generated in the transmit direction as described in Recommendation I.432.1, including the recommended modulo 2 addition (XOR) of the pattern 010101012 to the HEC bits. + +The generator polynomial coefficient set used and the HEC sequence generation procedure shall be in accordance with Recommendation I.432.1. + +### 7.2.3.3 Cell payload scrambling + +Scrambling of the cell payload field shall be used in the transmit direction to improve the security and robustness of the HEC cell delineation mechanism. In addition, it randomizes the data in the information field, for possible improvement of the transmission performance. The self synchronizing scrambler polynomial $X^{43} + 1$ and procedures defined in Recommendation I.432.1 shall be implemented. + +NOTE – This Recommendation is written on the assumption that the cell payload will be descrambled by an ATU-R receiver. + +### 7.2.3.4 Bit timing and ordering + +When interfacing ATM data bytes to the AS0 or AS1 bearer channel, the most significant bit (MSB) shall be sent first. The AS0 or AS1 bearer channel data rates shall be integer multiples 32 kbit/s, with bit timing synchronous with the ADSL downstream modem timing base (see 7.4.2.1 and 7.4.2.2). + +### 7.2.3.5 Cell Delineation + +The cell delineation function permits the identification of cell boundaries in the payload. It uses the HEC field in the cell header. + +Cell delineation shall be performed using a coding law checking the HEC field in the cell header according to the algorithm described in Recommendation I.432.1. The ATM cell delineation state machine is shown in Figure 7-3. The details of the state diagram are described below: + +- 1) In the HUNT state, the delineation process is performed by checking bit-by-bit for the correct HEC. Once such an agreement is found, it is assumed that one header has been found, and the method enters the PRESYNC state. When byte boundaries are available within the receiving Physical Layer prior to cell delineation as with the framing modes 1, 2 and 3 (see 7.4), the cell delineation process may be performed byte-by-byte. +- 2) In the PRESYNC state, the delineation process is performed by checking cell-by-cell for the correct HEC. The process repeats until the correct HEC has been confirmed *DELTA* (see Note) times consecutively. If an incorrect HEC is found, the process returns to the HUNT state. +- 3) In the SYNC state, the cell delineation will be assumed to be lost if an incorrect HEC is obtained *ALPHA* times consecutively. + +![Figure 7-3/G.992.1 – ATM cell delineation state machine diagram. The diagram shows three states: HUNT (Bit-by-bit), PRESYNC (Cell-by-cell), and SYNC (Cell-by-cell). Transitions are as follows: HUNT to PRESYNC on 'Correct HEC'; PRESYNC to HUNT on 'Incorrect HEC'; HUNT to SYNC on 'ALPHA consecutive incorrect HEC'; PRESYNC to SYNC on 'DELTA consecutive correct HEC'.](f57c7b37d7a05a99618104f390089f03_img.jpg) + +``` + +stateDiagram-v2 + [*] --> HUNT + HUNT --> PRESYNC : Correct HEC + PRESYNC --> HUNT : Incorrect HEC + HUNT --> SYNC : ALPHA consecutive incorrect HEC + PRESYNC --> SYNC : DELTA consecutive correct HEC + state "HUNT" as HUNT + state "PRESYNC" as PRESYNC + state "SYNC" as SYNC + note for HUNT "Bit-by-bit" + note for PRESYNC "Cell-by-cell" + note for SYNC "Cell-by-cell" + +``` + +Figure 7-3/G.992.1 – ATM cell delineation state machine diagram. The diagram shows three states: HUNT (Bit-by-bit), PRESYNC (Cell-by-cell), and SYNC (Cell-by-cell). Transitions are as follows: HUNT to PRESYNC on 'Correct HEC'; PRESYNC to HUNT on 'Incorrect HEC'; HUNT to SYNC on 'ALPHA consecutive incorrect HEC'; PRESYNC to SYNC on 'DELTA consecutive correct HEC'. + +NOTE – With reference to Recommendation I.432.1, no recommendation is made for the values of ALPHA and DELTA as the choice of these values is not considered to effect interoperability. However, it should be noted that the use of the values suggested in Recommendation I.432 (ALPHA = 7, DELTA = 6) may be inappropriate due to the particular transmission characteristics of ADSL. + +**Figure 7-3/G.992.1 – ATM cell delineation state machine** + +### 7.2.3.6 Header Error Control Verification + +The HEC covers the entire cell header. The code used for this function is capable of either: + +- single bit error correction; or +- multiple bit error detection. + +Error detection shall be implemented as defined in Recommendation I.432.1 with the exception that any HEC error shall be considered as a multiple bit error, and therefore, HEC error correction shall not be performed. + +### 7.2.4 Framing Structure for ATM transport + +An ATU-C configured for ATM transport shall support the full overhead framing structures 0 and 1 as specified in 7.4. The support of reduced overhead framing structures 2 and 3 is optional. + +The ATU-C transmitter shall preserve V-C interface byte boundaries (explicitly present or implied by ATM cell boundaries) at the U-C interface, independent of the U-C interface framing structure. + +To ensure framing structure 0 interoperability between an ATM ATU-C and an ATM cell TC plus an STM ATU-R (i.e. ATM over STM), the following shall apply: + +- an STM ATU-R transporting ATM cells and not preserving T-R byte boundaries at the U-R interface shall indicate during initialization that frame structure 0 is the highest frame structure supported; +- an STM ATU-R transporting ATM cells and preserving T-R byte boundaries at the U-R interface shall indicate during initialization that frame structure 0, 1, 2 or 3 is the highest frame structure supported, as applicable to the implementation; +- an ATM ATU-C receiver operating in framing structure 0 cannot assume that the ATU-R transmitter will preserve T-R interface byte boundaries at the U-R interface and shall therefore perform the cell delineation bit-by-bit (see 7.2.3.5). + +An ATU-C configured for ATM transport may support insertion of a Network Timing Reference (NTR). The network operator may choose not to insert the NTR. If inserted, the NTR shall be inserted in the U-C framing structure as described in 7.3.2. + +### 7.3 Network timing reference (NTR) + +#### 7.3.1 Need for NTR + +Some services require that a reference clock be available in the higher layers of the protocol stack (i.e. above the physical layer); this is used to guarantee end-to-end synchronization of transmit and receive sides. Examples are Voice and Telephony Over ATM (VTOA) and Desktop Video Conferencing (DVC). + +To support the distribution of a timing reference over the network, the ADSL system may transport an 8 kHz timing marker as NTR. This 8 kHz timing marker may be used for voice/video playback at the decoder (D/A converter) in DVC and VTOA applications. The 8 kHz timing marker is input to the ATU-C as part of the interface at the V-C reference point. + +#### 7.3.2 Transport of the NTR + +The intention of the NTR transport mechanism is that the ATU-C should provide timing information at the U-C reference point to enable the ATU-R to deliver to the T-R reference point timing information that has a timing accuracy corresponding to the accuracy of the clock provided to the V-C reference point. If provided, the NTR shall be inserted in the U-C framing structure as follows: + +- The ATU-C may generate an 8 kHz local timing reference (LTR) by dividing its sampling clock by the appropriate integer (276 if 2.208 MHz is used). +- It shall transmit the change in phase offset between the input NTR and LTR (measured in cycles of the 2.208 MHz clock, that is, units of approximately 452 ns) from the previous superframe to the present one; this shall be encoded into four bits ntr3-ntr0 (with ntr3 the MSB), representing a signed integer in the -8 to +7 range in 2's-complement notation. The bits ntr3-ntr0 shall be carried in the indicator bits 23 (ntr3) to 20 (ntr0); see Table 7-2. +- A positive value of the change of phase offset, $\Delta^2\phi$ shall indicate that the LTR is higher in frequency than the NTR. +- Alternatively, the ATU-C may choose to lock its downstream sampling clock (2.208 MHz) to 276 times the NTR frequency; in that case it shall encode $\Delta^2\phi$ to zero. + +The NTR has a maximum frequency variation of $\pm 32$ ppm. The LTR, as specified in 7.11.1, has a maximum frequency variation of $\pm 50$ ppm. The maximum mismatch is therefore $\pm 82$ ppm. This would result in an average change of phase offset of approximately $\pm 3.5$ clock cycles over one 17 ms superframe, which can be mapped into 4 overhead bits. + +One method that the ATU-C may use to measure this change of phase offset is shown in Figure 7-4. + +![Block diagram of the Δ²φ measurement implementation. The diagram shows two input signals: NTR and 2.208 MHz. The 2.208 MHz signal is processed through two 'count mod' blocks (276 and 136) to generate a 'MC' (maxcount) signal. The NTR signal is captured in a 'register'. The 'MC' signal from the 'count mod 136' block is also captured in a 'register'. The outputs of these two registers are fed into a summation block (Σ) to calculate the phase offset Δφ_n. The previous phase offset Δφ_{n-1} is also captured in a 'register' and fed into the summation block. The output of the summation block is Δ²φ. A note below the diagram states '(MC is maxcount indication before foldover to 0)' and a label 'T1532400-99' is present.](a8050baf48cc2c8e25d5ea2d1a67ef39_img.jpg) + +(MC is maxcount indication before foldover to 0) + +Block diagram of the Δ²φ measurement implementation. The diagram shows two input signals: NTR and 2.208 MHz. The 2.208 MHz signal is processed through two 'count mod' blocks (276 and 136) to generate a 'MC' (maxcount) signal. The NTR signal is captured in a 'register'. The 'MC' signal from the 'count mod 136' block is also captured in a 'register'. The outputs of these two registers are fed into a summation block (Σ) to calculate the phase offset Δφ\_n. The previous phase offset Δφ\_{n-1} is also captured in a 'register' and fed into the summation block. The output of the summation block is Δ²φ. A note below the diagram states '(MC is maxcount indication before foldover to 0)' and a label 'T1532400-99' is present. + +**Figure 7-4/G.992.1 – Example implementation of the $\Delta^2\phi$ measurement** + +## 7.4 Framing + +This subclause specifies framing of the downstream signal (ATU-C transmitter). The upstream framing (ATU-R transmitter) is specified in 8.4. + +Two types of framing are defined: full overhead and reduced overhead. Furthermore, two versions of full overhead and two versions of reduced overhead are defined. The four resulting framing modes are defined in Table 7-1 and shall be referred to as framing modes 0, 1, 2 and 3. + +**Table 7-1/G.992.1 – Definition of framing modes** + +| Framing structure | Description | +|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | Full overhead framing with asynchronous bit-to-modem timing (see 7.4.1) (i.e. enabled synchronization control mechanism, see 7.4.2) | +| 1 | Full overhead framing with synchronous bit-to-modem timing (see 7.4.1) (i.e. disabled synchronization control mechanism, see 7.4.2) | +| 2 | Reduced overhead framing with separate fast and sync byte in fast and interleaved latency buffer respectively (i.e. 64 kbit/s framing overhead) (see 7.4.3.1) | +| 3 | Reduced overhead framing with merged fast and sync byte, using either the fast or the interleaved latency buffer (i.e. 32 kbit/s framing overhead) (see 7.4.3.2) | + +Requirements for framing modes to be supported depend upon the ATU-C being configured for either STM or ATM transport, and are defined in 7.1.5 and 7.2.4 respectively. + +The ATU-C shall indicate during initialization the highest framing structure number it supports. If the ATU-C indicates it supports framing structure $k$ , it shall also support all framing structures $k - 1$ to 0. If the ATU-R indicates a lower framing structure number during initialization, the ATU-C shall fall back to the framing structure number indicated by the ATU-R. + +As specified in clause 5, outside the ASx/LSx serial interfaces data bytes are transmitted MSB first in accordance with Recommendations G.703, G.709, I.361, and I.432.1. All serial processing in the ADSL frame (e.g. CRC, scrambling, etc.) shall, however, be performed LSB first, with the outside world MSB considered by the ADSL as LSB. As a result, the first incoming bit (outside world MSB) will be the first processed bit inside the ADSL (ADSL LSB). + +### 7.4.1 Data symbols + +Figures 5-1 and 5-2 show functional block diagrams of the ATU-C transmitter with reference points for data framing. Up to four downstream simplex data channels and up to three duplex data channels shall be synchronized to the 4 kHz ADSL DMT frame rate, and multiplexed into two separate data buffers (fast and interleaved). A cyclic redundancy check (CRC), scrambling, and forward error correction (FEC) coding shall be applied to the contents of each buffer separately, and the data from the interleaved buffer shall then be passed through an interleaving function. The two data streams shall then be tone ordered as defined in 7.7, and combined into a data symbol that is input to the constellation encoder. After constellation encoding, the data shall be modulated to produce an analogue signal for transmission across the customer loop. + +A bit-level framing pattern shall not be inserted into the data symbols of the frame or superframe structure. DMT frame (i.e. symbol) boundaries are delineated by the cyclic prefix inserted by the modulator (see 7.12). Superframe boundaries are determined by the synchronization symbol, which shall also be inserted by the modulator, and which carries no user data (see 7.11.3). + +Because of the addition of FEC redundancy bytes and data interleaving, the data frames (i.e. bit-level data prior to constellation encoding) have different structural appearance at the three reference points through the transmitter. As shown in Figures 5-1 and 5-2, the reference points for which data framing will be described in the following subclauses are: + +- A (Mux data frame): the multiplexed, synchronized data after the CRC has been inserted (synchronization is described in 7.4.2, CRC is specified in 7.4.1.5. Mux data frames shall be generated at a nominal 4 kbaud (i.e. every 250 $\mu$ s). +- B (FEC output data frame): the data frame generated at the output of the FEC encoder at the DMT symbol rate, where an FEC block may span more than one DMT symbol period. +- C (constellation encoder input data frame): the data frame presented to the constellation coder. + +#### 7.4.1.1 Superframe structure + +ADSL uses the superframe structure shown in Figure 7-5. Each superframe is composed of 68 data frames, numbered from 0 to 67, which are encoded and modulated into DMT symbols, followed by a synchronization symbol, which carries no user or overhead bit-level data and is inserted by the modulator (see 7.11.3) to establish superframe boundaries. From the bit-level and user data perspective, the DMT symbol rate is 4000 baud (period = 250 $\mu$ s), but in order to allow for the insertion of the synchronization symbol the transmitted DMT symbol rate is $69/68 \times 4000$ baud. + +Each data frame within the superframe contains data from the fast buffer and the interleaved buffer. The size of each buffer depends on the assignment of bearer channels made during initialization (see 7.4.1.2 and 10.6.2). + +![Diagram of ADSL superframe structure showing frame layout and buffer organization.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg) + +The diagram illustrates the structure of an ADSL superframe and its associated data buffers. + +**Superframe Structure (17 ms):** + +- The superframe consists of 68 frames (0-67) followed by a Synch symbol. +- frame 0:** contains crc 0-7 in fast synch bytes. +- frame 1:** contains i.b.'s 0-7 in fast byte. +- frame 34:** contains i.b.'s 8-15 in fast byte. +- frame 35:** contains i.b.'s 16-23 in fast byte. +- Synch symbol:** contains no user or bit-level data. + +**frame data buffer ( $68/69 \times 0.25 \text{ ms}$ ):** + +- fast data buffer:** + - fast byte:** 1 byte. + - fast data:** $K_F$ bytes (together with fast byte, forms Mux data frame, point (A)). +- interleaved data buffer:** + - FECf redundancy:** $R_F$ bytes. + - (Interleaved data):** $N_I$ bytes (Constellation encoder input data frame, point (C)). +- The total length of the combined buffers is $N_F$ bytes (FEC output or constellation encoder input data frame, points (B), (C)). + +T1532410-99 + +Diagram of ADSL superframe structure showing frame layout and buffer organization. + +**Figure 7-5/G.992.1 – ADSL superframe structure – ATU-C transmitter** + +During each ADSL superframe, eight bits shall be reserved for the CRC on the fast data buffer (crc0-crc7), and 24 indicator bits (ib0-ib23) shall be assigned for OAM functions. As shown in Figure 7-6, the synchronization byte of the fast data buffer ("fast byte") carries the CRC check bits in frame 0 and the indicator bits in frames 1, 34 and 35. The fast byte in other frames is assigned in even-/odd-frame pairs to either the EOC or to synchronization control of the bearer channels assigned to the fast buffer. + +Bit 0 of the fast byte in an even-numbered frame (other than frames 0 and 34) and bit 0 of the fast byte of the odd-numbered frame immediately following shall be set to "0" to indicate these frames carry a synchronization control information. + +When they are not required for synchronization control, CRC, or indicator bits, the fast bytes of two successive ADSL frames, beginning with an even-numbered frame, may contain indications of "no synchronization action" (see 7.4.2), or alternatively, they may be used to transmit one EOC message, consisting of 13 bits. The indicator bits are defined in Table 7-2. + +Bit 0 of the fast byte in an even-numbered frame (other than frames 0 and 34) and bit 0 of the fast byte of the odd-numbered frame immediately following shall be set to "1" to indicate these frames carry a 13-bit EOC message plus one additional bit, r1 (see clause 9). The r1 bit is reserved for future use and shall be set to "1". + +![Diagram showing bit positions: a 1-bit arrow pointing to the right under the first bit, and an 8-bit arrow pointing to the right under the remaining bits.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +Even-numbered frames + +Odd-numbered frames +(immediately follow even-numbered frame to the left) + +| | | | | | | | | | | | | | | | | | | +|-----------------------|----------------------|------|------|------|------|------|------|------|------|-------|-------|-------|-------|------|------|------|-----| +| | msb | | | | | | | lsb | msb | | | | | | | | lsb | +| Frames 0, 1 | crc7 | crc6 | crc5 | crc4 | crc3 | crc2 | crc1 | crc0 | ib7 | ib6 | ib5 | ib4 | ib3 | ib2 | ib1 | ib0 | | +| Frames 34, 35 | ib15 | ib14 | ib13 | ib12 | ib11 | ib10 | ib9 | ib8 | ib23 | ib22 | ib21 | ib20 | ib19 | ib18 | ib17 | ib16 | | +| Frames 2-33,
36-67 | eoc | eoc6 | eoc5 | eoc4 | eoc3 | eoc2 | eoc1 | r1 | 1 | eoc13 | eoc12 | eoc11 | eoc10 | eoc9 | eoc8 | eoc7 | 1 | +| | Synch Control | sc7 | sc6 | sc5 | sc4 | sc3 | sc2 | sc1 | 0 | sc7 | sc6 | sc5 | sc4 | sc3 | sc2 | sc1 | 0 | + +T1532420-99 + +1 bit                      8 bits + +Diagram showing bit positions: a 1-bit arrow pointing to the right under the first bit, and an 8-bit arrow pointing to the right under the remaining bits. + +In all frames bit 7 = MSB and bit 0 = LSB. + +**Figure 7-6/G.992.1 – Fast synchronization byte ("fast byte") format – ATU-C transmitter** + +**Table 7-2/G.992.1 – Definition of indicator bits, ATU-C transmitter +(fast data buffer, downstream direction)** + +| Indicator bit (Note 1) | Definition (Note 2) | +|---------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------| +| Ib0-ib7 | Reserved for future use | +| Ib8 | FEFE-I | +| Ib9 | FECC-I | +| Ib10 | FEFE-F | +| Ib11 | FECC-F | +| Ib12 | LOS | +| Ib13 | RDI | +| Ib14 | NCD-I (used for ATM only, shall be set to "1" for STM) | +| Ib15 | NCD-F (used for ATM only, shall be set to "1" for STM) | +| Ib16 | HEC-I (used for ATM only, shall be set to "1" for STM) | +| Ib17 | HEC-F (used for ATM only, shall be set to "1" for STM) | +| Ib18-19 | Reserved for future use | +| Ib20-23 | NTR0-3 (if NTR is not transported, ib20-23 shall be set to "1" – they are active low) | +| NOTE 1 – See 9.3.1 for the definition of the bits and their use. | | +| NOTE 2 – Because all indicator bits are defined as active low, reserved bits shall be set to "1". | | + +Eight bits per ADSL superframe shall be used for the CRC on the interleaved data buffer (crc0-crc7). As shown in Figures 7-7 and 7-9, the synchronization byte of the interleaved data buffer ("sync byte") carries the CRC check bits for the previous superframe in frame 0. In all other frames (1 through 67), the sync byte shall be used for synchronization control of the bearer channels assigned to the interleaved data buffer or used to carry an ADSL overhead control (AOC) channel. In the full overhead mode (see 7.4.1.2), when any bearer channel appears in the interleaved buffer, then + +the AOC data shall be carried in the LEX byte, and the sync byte shall designate when the LEX byte contains AOC data and when it contains data bytes from the bearer channel. When no bearer channels are allocated to the interleaved data buffer (i.e. all $B_i(ASx) = B_i(LSx) = 0$ ), then the sync byte shall carry the AOC data directly (AEX and LEX bytes, described in 7.4.1.2, do not exist in the interleaved buffer in this case). The format of the sync byte is described in 7.4.2.2. + +![](bb4d2112ed07e2031c92fbff3494af9f_img.jpg) + +| | | | | | | | | | | | +|-------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------|------|------|------|------|------|------|------|-------------| +| Frame 0 | | msb | | | | | | | | | +| | | crc7 | crc6 | crc5 | crc4 | crc3 | crc2 | crc1 | crc0 | | +| | | | | | | | | | | | +| Frames 1-67 |
{
If signals are allocated to
interleave buffer:

If no signals are allocated to
interleave buffer:
| Synch
Control | sc7 | sc6 | sc5 | sc4 | sc3 | sc2 | sc1 | sc0 | +| | | aoc | aoc7 | aoc6 | aoc5 | aoc4 | aoc3 | aoc2 | aoc1 | aoc0 | +| | | | | | | | | | | T1535390-00 | + +NOTE – The names "fast byte" and "sync byte" are abbreviations for, and are used interchangeably with, "fast synchronization byte" and "interleaved synchronization byte", respectively. + +**Figure 7-7/G.992.1 – Interleaved synchronization byte ("sync byte") format – +ATU-C transmitter** + +#### 7.4.1.2 Frame structure (with full overhead) + +Each data frame shall be encoded into a DMT symbol, as described in 7.7 through 7.9. As is shown in Figure 7-5, each frame is composed of a fast data buffer and an interleaved data buffer, and the frame structure has a different appearance at each of the reference points (A, B and C). The bytes of the fast data buffer shall be clocked into the constellation encoder first, followed by the bytes of the interleaved data buffer. Bytes are clocked least significant bit first. + +Each bearer channel shall be assigned to either the fast or the interleaved buffer during initialization (see 10.6.2), and a pair of bytes, $[B_F, B_I]$ , transmitted for each bearer channel, where $B_F$ and $B_I$ designate the number of bytes allocated to the fast and interleaved buffers, respectively. + +The seven $[B_F, B_I]$ pairs to specify the downstream bearer channel rates are: + +- $B_F(ASx), B_I(ASx)$ for $X = 0, 1, 2$ and $3$ , for the downstream simplex channels; +- $B_F(LSx), B_I(LSx)$ for $X = 0, 1$ and $2$ , for the (downstream transport of the) duplex channels. + +The rules for allocation are: + +- for any bearer channel, $X$ , except the 16 kbit/s C-channel option, either $B_F(X)$ = the number of bytes per frame of the fast buffer and $B_I(X) = 0$ , or $B_F(X) = 0$ and $B_I(X)$ = the number of bytes per frame of the interleaved buffer; +- for the 16 kbit/s C-channel option, $B_F(LS0) = 255$ ( $11111111_2$ ) and $B_I(LS0) = 0$ , or $B_F(LS0) = 0$ and $B_I(LS0) = 255$ . + +##### 7.4.1.2.1 Fast data buffer (with full overhead) + +The frame structure of the fast data buffer shall be as shown in Figure 7-8 for reference points A and B, which are defined in Figures 5-1 and 5-2. + +![Diagram of Figure 7-8/G.992.1 – Fast data buffer – ATU-C transmitter. The diagram shows the structure of data frames at different reference points. At the top, a long horizontal arrow labeled 'N_F bytes' spans the 'FEC output (point B) or constellation encoder input (point C) data frame'. Below it, a shorter arrow labeled 'K_F bytes' spans the 'Mux data frame (point A)'. The bottom part is a segmented row representing the bytes: 'Fast Byte' (1 byte), 'AS0' (B_F(AS0) bytes), 'AS1' (B_F(AS1) bytes), 'AS2' (B_F(AS2) bytes), 'AS3' (B_F(AS3) bytes), 'LS0' (C_F(LS0) bytes), 'LS1' (B_F(LS1) bytes), 'LS2' (B_F(LS2) bytes), 'AEX' (A_F bytes), 'LEX' (L_F bytes), and 'FEC bytes' (R_F bytes). Vertical dashed lines align the boundaries of these frames and segments.](cbb2d311b20781a595488445ded48d0a_img.jpg) + +Diagram of Figure 7-8/G.992.1 – Fast data buffer – ATU-C transmitter. The diagram shows the structure of data frames at different reference points. At the top, a long horizontal arrow labeled 'N\_F bytes' spans the 'FEC output (point B) or constellation encoder input (point C) data frame'. Below it, a shorter arrow labeled 'K\_F bytes' spans the 'Mux data frame (point A)'. The bottom part is a segmented row representing the bytes: 'Fast Byte' (1 byte), 'AS0' (B\_F(AS0) bytes), 'AS1' (B\_F(AS1) bytes), 'AS2' (B\_F(AS2) bytes), 'AS3' (B\_F(AS3) bytes), 'LS0' (C\_F(LS0) bytes), 'LS1' (B\_F(LS1) bytes), 'LS2' (B\_F(LS2) bytes), 'AEX' (A\_F bytes), 'LEX' (L\_F bytes), and 'FEC bytes' (R\_F bytes). Vertical dashed lines align the boundaries of these frames and segments. + +T1532430-99 + +**Figure 7-8/G.992.1 – Fast data buffer – ATU-C transmitter** + +The following shall hold for the parameters shown in Figure 7-8: + +$$C_F(LS0) = 0 \quad \text{if } B_F(LS0) = 255(11111111_2) \quad (7-1)$$ + +$$= B_F(LS0) \quad \text{otherwise}$$ + +$$N_F = K_F + R_F \quad (7-2)$$ + +where $R_F$ = number of FEC redundancy bytes, and + +$$K_F = 1 + \sum_{i=0}^3 B_F(ASi) + A_F + C_F(LS0) + \sum_{j=1}^2 B_F(LSj) + L_F \quad (7-3)$$ + +where: + +$$A_F = 0 \quad \text{if } \sum_{i=0}^3 B_F(ASi) = 0 \quad (7-4)$$ + +$$= 1 \quad \text{otherwise}$$ + +and: + +$$L_F = 0 \quad \text{if } B_F(ASi) = 0 \text{ for } i = 0-3 \text{ and } B_F(LSj) = 0 \text{ for } j = 0-2 \quad (7-5)$$ + +$$= 1 \quad \text{otherwise (including } B_F(LS0) = 255)$$ + +At reference point A (Mux data frame) in Figures 5-1 and 5-2, the fast buffer shall always contain at least the fast byte. This is followed by $B_F(AS0)$ bytes of channel AS0, then $B_F(AS1)$ bytes of channel AS1, $B_F(AS2)$ bytes of channel AS2 and $B_F(AS3)$ bytes of channel AS3. Next come the bytes for any duplex (LSx) channels allocated to the fast buffer. If any $B_F(ASx)$ is non-zero, then both an AEX and an LEX byte follow the bytes of the last LSx channel, and if any $B_F(LSx)$ is non-zero, the LEX byte shall be included. + +When $B_F(LS0) = 255$ , no bytes are included for the LS0 channel. Instead, the 16 kbit/s C-channel shall be transported in every other LEX byte on average, using the sync byte to denote when to add the LEX byte to the LS0 bearer channel. + +$R_F$ FEC redundancy bytes shall be added to the mux data frame (reference point A) to produce the FEC output data frame (reference point B), where $R_F$ is given in the RATES1 options used during + +initialization. + +Because the data from the fast buffer is not interleaved, the constellation encoder input data frame (reference point C) is identical to the FEC output data frame (reference point B). + +#### 7.4.1.2.2 Interleaved data buffer (with full overhead) + +The frame structure of the interleaved data buffer is shown in Figure 7-9 for reference points A and B, which are defined in Figures 5-1 and 5-2. + +![Figure 7-9/G.992.1 – Interleaved data buffer, ATU-C transmitter. The diagram shows the mapping of a Mux data frame at point A into FEC output data frames. The top part shows a single Mux data frame of K_I bytes consisting of: Sync Byte (1 byte), AS0 (B_I(AS0) bytes), AS1 (B_I(AS1) bytes), AS2 (B_I(AS2) bytes), AS3 (B_I(AS3) bytes), LS0 (C_I(LS0) bytes), LS1 (B_I(LS1) bytes), LS2 (B_I(LS2) bytes), AEX (A_I bytes), and LEX (L_I bytes). The middle part shows S such Mux data frames (#0 to #S-1), each K_I bytes long, followed by R_I FEC bytes. The bottom part shows the resulting FEC output data frames (#0 to #S-1), each N_I bytes long.](f142b022cfc716cd967297f027efe647_img.jpg) + +Figure 7-9/G.992.1 – Interleaved data buffer, ATU-C transmitter. The diagram shows the mapping of a Mux data frame at point A into FEC output data frames. The top part shows a single Mux data frame of K\_I bytes consisting of: Sync Byte (1 byte), AS0 (B\_I(AS0) bytes), AS1 (B\_I(AS1) bytes), AS2 (B\_I(AS2) bytes), AS3 (B\_I(AS3) bytes), LS0 (C\_I(LS0) bytes), LS1 (B\_I(LS1) bytes), LS2 (B\_I(LS2) bytes), AEX (A\_I bytes), and LEX (L\_I bytes). The middle part shows S such Mux data frames (#0 to #S-1), each K\_I bytes long, followed by R\_I FEC bytes. The bottom part shows the resulting FEC output data frames (#0 to #S-1), each N\_I bytes long. + +**Figure 7-9/G.992.1 – Interleaved data buffer, ATU-C transmitter** + +The following shall hold for the parameters shown in Figure 7-9: + +$$C_I(LS0) = \begin{cases} 0 & \text{if } B_I(LS0) = 255(11111111_2) \\ B_I(LS0) & \text{otherwise} \end{cases} \quad (7-6)$$ + +$$N_I = (S \times K_I + R_I)/S \quad (7-7)$$ + +where $R_I$ = number of FEC redundancy bytes and $S$ = number of DMT symbols per FEC codeword. + +$$K_I = 1 + \sum_{i=0}^3 B_I(ASi) + A_I + C_I(LS0) + \sum_{j=1}^2 B_I(LSj) + L_I \quad (7-8)$$ + +where: + +$$\begin{aligned} A_I &= 0 && \text{if } \sum_{i=0}^3 BI(AS_i) = 0 \\ &= 1 && \text{otherwise} \end{aligned} \quad (7-9)$$ + +and: + +$$\begin{aligned} L_I &= 0 && \text{if } B_I(AS_i) = 0 \text{ for } i = 0-3 \text{ and } B_I(LS_j) = 0 \text{ for } j = 0-2 \\ &= 1 && \text{otherwise (including } B_I(LS_0) = 255) \end{aligned} \quad (7-10)$$ + +At reference point A, the Mux data frame, the interleaved data buffer shall always contain at least the sync byte. The rest of the buffer shall be built in the same manner as the fast buffer, substituting $B_I$ in place of $B_F$ . The length of each mux data frame is $K_I$ bytes, as defined in Figure 7-9. + +The FEC coder shall take in $S$ mux data frames and append $R_I$ FEC redundancy bytes to produce the FEC codeword of length $N_{FEC} = S \times K_I + R_I$ bytes. The FEC output data frames shall contain $N_I = N_{FEC}/S$ bytes, where $N_I$ is an integer. When $S > 1$ , then for the $S$ frames in an FEC codeword, the FEC output Data Frame (reference point B) shall partially overlap two mux data frames for all except the last frame, which shall contain the $R_I$ FEC redundancy bytes. + +The FEC output data frames are interleaved to a specified interleave depth. The interleaving process (see 7.6.3) delays each byte of a given FEC output data frame a different amount, so that the constellation encoder input data frames will contain bytes from many different FEC data frames. At reference point A in the transmitter, mux data frame 0 of the interleaved data buffer is aligned with the ADSL superframe and mux data frame 0 of the fast data buffer (this is not true at reference point C). At the receiver, the interleaved data buffer will be delayed by $(S \times \text{interleave depth} \times 250) \mu\text{s}$ with respect to the fast data buffer, and data frame 0 (containing the CRC bits for the interleaved data buffer) will appear a fixed number of frames after the beginning of the receiver superframe. + +#### 7.4.1.3 Hyperframe Structure (Annex C only) + +For Annex C, see C.4.3.2. + +#### 7.4.1.4 Subframe Structure (Annex C only) + +For Annex C, see C.4.3.3. + +#### 7.4.1.5 Cyclic redundancy check (CRC) + +Two cyclic redundancy checks (CRCs) – one for the fast data buffer and one for the interleaved data buffer – shall be generated for each superframe and transmitted in the first frame of the following superframe. Eight bits per buffer type (fast or interleaved) per superframe are allocated to the CRC check bits (7.4.1.1). These bits are computed from the $k$ message bits using the equation: + +$$\text{crc}(D) = M(D) D^8 \text{ modulo } G(D) \quad (7-11)$$ + +where: + +$$M(D) = m_0 D^{k-1} + m_1 D^{k-2} + \dots + m_{k-2} D + m_{k-1} \quad (7-12)$$ + +is the message polynomial, + +$$G(D) = D^8 + D^4 + D^3 + D^2 + 1 \quad (7-13)$$ + +is the generating polynomial, + +$$\text{crc}(D) = c_0 D^7 + c_1 D^6 + \dots + c_6 D + c_7 \quad (7-14)$$ + +is the check polynomial, and $D$ is the delay operator. That is, CRC is the remainder when $M(D) D^8$ is divided by $G(D)$ . The CRC check bits are transported in the synchronization bytes (fast and interleaved, 8 bits each) of frame 0 for each data buffer. + +The bits (*i.e.* message polynomials) covered by the CRC include: + +- fast data buffer: + - frame 0: ASx bytes ( $X = 0, 1, 2, 3$ ), LSx bytes ( $X = 0, 1, 2$ ), followed by any AEX and LEX bytes; + - all other frames: fast byte, followed by ASx bytes ( $X = 0, 1, 2, 3$ ), LSx bytes ( $X = 0, 1, 2$ ), and any AEX and LEX bytes. +- interleaved data buffer: + - frame 0: ASx bytes ( $X = 0, 1, 2, 3$ ), LSx bytes ( $X = 0, 1, 2$ ), followed by any AEX and LEX bytes; + - all other frames: sync byte, followed by ASx bytes ( $X = 0, 1, 2, 3$ ), LSx bytes ( $X = 0, 1, 2$ ), and any AEX and LEX bytes. + +Each byte shall be clocked into the CRC least significant bit first. + +The number of bits over which the CRC is computed varies with the allocation of bytes to the fast and interleaved data buffers (the numbers of bytes in ASx and LSx vary according to the $[B_F, B_I]$ pairs; AEX is present in a given buffer only if at least one ASx is allocated to that buffer; LEX is present in a given buffer only if at least one ASx or one LSx is allocated to that buffer). + +Because of the flexibility in assignment of bearer channels to the fast and interleaved data buffers, CRC field lengths over an ADSL superframe will vary from approximately 67 bytes to approximately 14 875 bytes. + +## 7.4.2 Synchronization + +If the bit timing base of the input user data streams is not synchronous with the ADSL modem timing base, the input data streams shall be synchronized to the ADSL timing base using the synchronization control mechanism (consisting of synchronization control byte and the AEX and LEX bytes). Forward-error-correction coding shall always be applied to the synchronization control byte(s). + +If the bit timing base of the input user data streams is synchronous with the ADSL modem timing base, then the synchronization control mechanism is not needed, and the synchronization control byte shall always indicate "no synchronization action" (see Tables 7-3 and 7-4). + +### 7.4.2.1 Synchronization for the fast data buffer + +Synchronization control for the fast data buffer may occur in frames 2 through 33, and 36 through 67 of an ADSL superframe as described in 7.4.1.1, where the fast byte may be used as the synchronization control byte. No synchronization action shall be taken for those frames for which the fast byte is used for CRC, fixed indicator bits, or EOC. + +The format of the fast byte when used as synchronization control for the fast data buffer shall be as given in Table 7-3. + +**Table 7-3/G.992.1 – Fast byte format for synchronization** + +| Bits | Designation | Codes | +|----------|---------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| sc7, sc6 | ASx bearer channel designator | "00 2 ": AS0
"01 2 ": AS1
"10 2 ": AS2
"11 2 ": AS3 | +| sc5, sc4 | Synchronization control for the designated ASx bearer channel | "00 2 ": no synchronization action
"01 2 ": add AEX byte to designated ASx bearer channel
"11 2 ": add AEX and LEX bytes to ASx bearer channel
"10 2 ": delete last byte from designated ASx bearer channel | +| sc3, sc2 | LSx bearer channel designator | "00 2 ": LS0
"01 2 ": LS1
"10 2 ": LS2
"11 2 ": no synchronization action | +| sc1 | Synchronization control for the designated LSx bearer channel | "1 2 ": add LEX byte to designated LSx bearer channel
"0 2 ": delete last byte from designated LSx bearer channel | +| sc0 | Synchronization/EOC designator | "0 2 ": perform synchronization control as indicated in sc7-sc1
"1 2 ": this byte is part of an EOC frame | + +ADSL deployments may need to interwork with DS1 (1.544 Mbit/s) or DS1C (3.152 Mbit/s) rates. The synchronization control option that allows adding up to two bytes to an ASx bearer channel provides sufficient overhead capacity to transport combinations of DS1 or DS1C channels transparently (without interpreting or stripping and regenerating the framing embedded within the DS1 or DS1C). The synchronization control algorithm shall, however, guarantee that the fast byte in some minimum number of frames is available to carry EOC frames, so that a minimum EOC rate (4 kbit/s) may be maintained. + +When the data rate of the C-channel is 16 kbit/s, the LS0 bearer channel is transported in the LEX byte, using the "add LEX byte to designated LSx channel", with LS0 as the designated channel, every other frame on average. + +If the bit timing base of the input bearer channels (ASx, LSx) is synchronous with the ADSL modem timing base then ADSL systems need not perform synchronization control by adding or deleting AEX or LEX bytes to/from the designated ASx and LSx channels, and the synchronization control byte shall indicate "no synchronization action" (i.e. sc7-0 coded "XX0011X02", with X discretionary). + +#### 7.4.2.2 Synchronization for the interleaved data buffer + +Synchronization control for the interleaved data buffer can occur in frames 1 through 67 of an ADSL superframe as described in 7.4.1.1, where the sync byte may be used as the synchronization control byte. No synchronization action shall be taken during frame 0, where the sync byte is used for CRC during frames when the LEX byte carries the AOC. + +The format of the sync byte when used as synchronization control for the interleaved data buffer shall be as given in Table 7-4. In the case where no signals are allocated to the interleaved data buffer, the sync byte shall carry the AOC data directly, as shown in Figure 7-7 in 7.4.1.1. + +**Table 7-4/G.992.1 – Sync byte format for synchronization** + +| Bits | Designation | Codes | +|----------|---------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| sc7, sc6 | ASx bearer channel designator | "00 2 ": AS0
"01 2 ": AS1
"10 2 ": AS2
"11 2 ": AS3 | +| sc5, sc4 | Synchronization control for the designated ASx bearer channel | "00 2 ": no synchronization action
"01 2 ": add AEX byte to designated ASx bearer channel
"11 2 ": add AEX and LEX bytes to ASx bearer channel
"10 2 ": delete last byte from designated ASx bearer channel | +| sc3, sc2 | LSx bearer channel designator | "00 2 ": LS0
"01 2 ": LS1
"10 2 ": LS2
"11 2 ": no synchronization action | +| sc1 | Synchronization control for the designated LSx bearer channel | "1 2 ": add LEX byte to designated LSx bearer channel
"0 2 ": delete last byte from designated LSx bearer channel | +| sc0 | Synchronization/AOC designator | "0 2 ": perform synchronization control as indicated in sc7-sc1
"1 2 ": LEX byte carries ADSL overhead control channel data; synchronization control is allowed for "add AEX" or "delete" as indicated in sc7-sc1 | + +ADSL deployments may need to interwork with DS1 (1.544 Mbit/s) or DS1C (3.152 Mbit/s) rates. The synchronization control option that allows adding up to two bytes to an ASx bearer channel provides sufficient overhead capacity to transport combinations of DS1 or DS1C channels transparently (without interpreting or stripping and regenerating the framing embedded within the DS1 or DS1C). + +When the data rate of the C-channel is 16 kbit/s, the LS0 bearer channel is transported in the LEX byte, using the "add LEX byte to designated LSx channel", with LS0 as the designated channel, every other frame on average. + +If the bit timing base of the input bearer channels (ASx, LSx) is synchronous with the ADSL modem timing base then ADSL systems need not perform synchronization control by adding or deleting AEX or LEX bytes to/from the designated ASx and LSx channels, and the synchronization control byte shall indicate "no synchronization action". In this case, and when framing mode 1 is used, the sc7-0 shall always be coded "XX0011XX2", with X discretionary. When sc0 is set to 1, the LEX byte shall carry AOC. When sc0 is set to 0, the LEX byte shall be coded 0016. The sc0 may be set to 0 only in between transmissions of 5 concatenated and identical AOC messages. + +### 7.4.3 Reduced overhead framing + +The format described in 7.4.1.2 for full overhead framing includes overhead to allow for the synchronization of seven ASx and LSx bearer channels. When the synchronization function described in 7.4.2 is not required, the ADSL equipment may operate in a reduced overhead mode. This mode retains all the full overhead mode functions except synchronization control. When using the reduced overhead framing, the framing structure shall be as defined in 7.4.3.1 or 7.4.3.2. + +### 7.4.3.1 Reduced overhead framing with separate fast and sync bytes + +The AEX and LEX bytes shall be eliminated from the ADSL frame format, and both the fast and sync bytes shall carry overhead information as described in 7.4.1.2. The fast byte carries the fast buffer CRC, indicator bits, and EOC messages, and the sync byte carries the interleave buffer CRC and AOC messages. The assignment of overhead functions to fast and sync bytes when using the full overhead framing and when using the reduced overhead framing with separate fast and sync bytes shall be as shown in Table 7-5. + +In the reduced overhead framing with separate fast and sync bytes, the structure of the fast data buffer shall be as shown in 7.4.1.2.1 with AF and LF set to "0". The structure of the interleaved data buffer shall be as shown in 7.4.1.2.2 with AI and LI set to "0". + +**Table 7-5/G.992.1 – Overhead functions for framing modes** + +| Frame Number | Full Overhead Mode | | Reduced Overhead Mode | | +|------------------|--------------------|-----------------|-----------------------|-----------------| +| | Fast Sync | Interleave Sync | Fast Sync | Interleave Sync | +| 0 | fast CRC | interleaved CRC | fast CRC | interleaved CRC | +| 1 | IB0-7 | sync or AOC | IB0-7 | AOC | +| 34 | IB8-15 | sync or AOC | IB8-15 | AOC | +| 35 | IB16-23 | sync or AOC | IB16-23 | AOC | +| all other frames | sync or EOC | sync or AOC | sync or EOC
(Note) | AOC | + +NOTE – In the reduced overhead mode, only "no synchronization action" code shall be used. + +### 7.4.3.2 Reduced overhead framing with merged fast and sync bytes + +In the single latency mode, data is assigned to only one data buffer (fast or interleaved). If data is assigned to only the fast buffer, then only the fast byte shall be used to carry overhead information. If data is assigned to only the interleaved buffer, then only the sync byte shall be used to carry overhead information. Reduced overhead framing with merged fast and sync bytes shall not be used when operating in dual latency mode. + +For ADSL systems transporting data using a single data buffer (fast or interleaved), the CRC, indicator, EOC and AOC function shall be carried in a single overhead byte assigned to separate data frames within the superframe structure. The CRC remains in frame 0 and the indicator bits in frames 1, 34 and 35. The AOC and EOC bytes are assigned to alternate pairs of frames. For ADSL equipment operating in single latency mode using the reduced overhead framing with merged fast and sync bytes, the assignment of overhead functions shall be as shown in Table 7-6. + +In the single latency mode using the reduced overhead framing with merged fast and sync bytes, only one data buffer shall be used. If the fast data buffer is used, the structure of the fast data buffer shall be as shown in 7.4.1.2.1 (with AF and LF set to "0") and the interleaved data buffer shall be empty (no sync byte and KI = 0). If the interleaved data buffer is used, the structure of the interleaved data buffer shall be as shown in 7.4.1.2.2 (with AI and LI set to "0") and the fast data buffer shall be empty (no fast byte and KF = 0). + +**Table 7-6/G.992.1 – Overhead functions for reduced overhead mode – +with merged fast and sync bytes** + +| Frame Number | (Fast Buffer Only)
Fast Byte format | (Interleaved Buffer Only)
Sync Byte format | +|-----------------------------------------------------------------------------------------------|----------------------------------------|-----------------------------------------------| +| 0 | Fast CRC | Interleaved CRC | +| 1 | IB0-7 | IB0-7 | +| 34 | IB8-15 | IB8-15 | +| 35 | IB16-23 | IB16-23 | +| 4n+2, 4n+3
with n = 0...16, n ≠ 8 | EOC or sync (Note) | EOC or sync (Note) | +| 4n, 4n+1
with n = 0...16, n ≠ 0 | AOC | AOC | +| NOTE – In the reduced overhead mode, only the "no synchronization action" code shall be used. | | | + +### 7.5 Scramblers + +The binary data streams output (LSB of each byte first) from the fast and interleaved data buffers shall be scrambled separately using the following algorithm for both: + +$$d'_n = d_n \oplus d'_{n-18} \oplus d'_{n-23} \quad (7-15)$$ + +where $d_n$ is the $n$ -th output from the fast or interleaved buffer (i.e. input to the scrambler), and $d'_n$ is the $n$ -th output from the corresponding scrambler. This is illustrated in Figure 7-10. + +![Figure 7-10/G.992.1 – Scrambler. A block diagram showing the scrambling process. 'Byte Input (from CRC block)' enters a 'Parallel to serial LSB first' block. The resulting serial bit stream d_n is XORed with a feedback signal to produce d'_n. The d'_n stream is then converted back by a 'Serial to Parallel LSB first' block to produce 'Byte Output (to RS coder block)'. The feedback path for d'_n consists of a shift register with taps at d'_{n-18} and d'_{n-23}, which are XORed together and then XORed with the input d_n.](753e6cc5dcad1a478caa2c7ec3a6c0a3_img.jpg) + +``` + +graph LR + Input[Byte Input from CRC block] --> P2S[Parallel to serial LSB first] + P2S --> DN((+)) + DN --> S2P[Serial to Parallel LSB first] + S2P --> Output[Byte Output to RS coder block] + DN -- d'_n --> D1[d'_{n-1}] + D1 --> D2[d'_{n-2}] + D2 --> Dots1[...] + Dots1 --> D18[d'_{n-18}] + D18 --> XOR2((+)) + D18 --> Dots2[...] + Dots2 --> D23[d'_{n-23}] + D23 --> XOR2 + XOR2 --> DN + +``` + +Figure 7-10/G.992.1 – Scrambler. A block diagram showing the scrambling process. 'Byte Input (from CRC block)' enters a 'Parallel to serial LSB first' block. The resulting serial bit stream d\_n is XORed with a feedback signal to produce d'\_n. The d'\_n stream is then converted back by a 'Serial to Parallel LSB first' block to produce 'Byte Output (to RS coder block)'. The feedback path for d'\_n consists of a shift register with taps at d'\_{n-18} and d'\_{n-23}, which are XORed together and then XORed with the input d\_n. + +**Figure 7-10/G.992.1 – Scrambler** + +These scramblers are applied to the serial data streams without reference to any framing or symbol synchronization. Descrambling in receivers can likewise be performed independent of symbol synchronization. + +## 7.6 Forward error correction + +The ATU-C shall support downstream transmission with at least any combination of the FEC coding capabilities shown in Table 7-7. + +**Table 7-7/G.992.1 – Minimum FEC coding capabilities for ATU-C** + +| Parameter | Fast buffer | Interleaved buffer | +|--------------------------------------------------------------------------------------------|---------------------------------------------------|----------------------------------------------------------| +| Parity bytes per R-S codeword | $R_F = 0, 2, 4, 6, 8, 10, 12, 14, 16$
(Note 1) | $R_I = 0, 2, 4, 6, 8, 10, 12, 14, 16$
(Notes 1 and 2) | +| DMT symbols per R-S codeword | $S = 1$ | $S = 1, 2, 4, 8, 16$ | +| Interleave depth | Not applicable | $D = 1, 2, 4, 8, 16, 32, 64$ | +| NOTE 1 – $R_F$ can be $> 0$ only if $K_F > 0$ , and $R_I$ can be $> 0$ only if $K_I > 0$ . | | | +| NOTE 2 – $R_I$ shall be an integer multiple of $S$ . | | | + +The ATU-C shall also support upstream transmission with at least any combination of the FEC coding capabilities shown in Table 8-3. + +### 7.6.1 Reed-Solomon coding + +$R$ (i.e. $R_F$ or $R_I$ ) redundant check bytes $c_0, c_1, \dots, c_{R-2}, c_{R-1}$ shall be appended to $K$ (i.e. $K_F$ or $S \times K_I$ ) message bytes $m_0, m_1, \dots, m_{K-2}, m_{K-1}$ to form a Reed-Solomon codeword of size $N = K + R$ bytes. The check bytes are computed from the message byte using the equation: + +$$C(D) = M(D) D^R \text{ modulo } G(D) \quad (7-16)$$ + +where: + +$$M(D) = m_0 D^{K-1} + m_1 D^{K-2} + \dots + m_{K-2} D + m_{K-1} \quad (7-17)$$ + +is the message polynomial, + +$$C(D) = c_0 D^{R-1} + c_1 D^{R-2} + \dots + c_{R-2} D + c_{R-1} \quad (7-18)$$ + +is the check polynomial, and + +$$G(D) = \prod_{i=0}^{R-1} (D + \alpha^i) \quad (7-19)$$ + +is the generator polynomial of the Reed-Solomon code, where the index of the product runs from $i = 0$ to $R-1$ . That is, $C(D)$ is the remainder obtained from dividing $M(D) D^R$ by $G(D)$ . The arithmetic is performed in the Galois Field GF(256), where $\alpha$ is a primitive element that satisfies the primitive binary polynomial $x^8 + x^4 + x^3 + x^2 + 1$ . A data byte $(d_7, d_6, \dots, d_1, d_0)$ is identified with the Galois Field element $d_7\alpha^7 + d_6\alpha^6 + \dots + d_1\alpha + d_0$ + +The number of check bytes $R$ , and the codeword size $N$ vary, as explained in 7.4. + +### 7.6.2 Reed-Solomon Forward Error Correction Superframe Synchronization + +When entering the SHOWTIME state after completion of Initialization and Fast Retrain, the ATU shall align the first byte of the first Reed-Solomon codeword with the first data byte of DF 0. + +### 7.6.3 Interleaving + +The Reed-Solomon codewords in the interleaved buffer shall be convolutionally interleaved. The interleaving depth varies, as explained in 7.4, but shall always be a power of 2. Convolutional + +interleaving is defined by the rule: + +Each of the $N$ bytes $B_0, B_1, \dots, B_{N-1}$ in a Reed-Solomon codeword is delayed by an amount that varies linearly with the byte index. More precisely, byte $D_i$ (with index $i$ ) is delayed by $(D-1) \times i$ bytes, where $D$ is the interleave depth. + +An example for $N = 5, D = 2$ is shown in Table 7-8, where $B_{ji}$ denotes the $i$ -th byte of the $j$ -th codeword. + +**Table 7-8/G.992.1 – Convolutional interleaving example for $N = 5, D = 2$** + +| | | | | | | | | | | | +|--------------------|----------|------------|----------|------------|----------|------------|------------|------------|------------|------------| +| Interleaver input | $B_{j0}$ | $B_{j1}$ | $B_{j2}$ | $B_{j3}$ | $B_{j4}$ | $B_{j+10}$ | $B_{j+11}$ | $B_{j+12}$ | $B_{j+13}$ | $B_{j+14}$ | +| Interleaver output | $B_{j0}$ | $B_{j-13}$ | $B_{j1}$ | $B_{j-14}$ | $B_{j2}$ | $B_{j+10}$ | $B_{j3}$ | $B_{j+11}$ | $B_{j4}$ | $B_{j+12}$ | + +With the above-defined rule, and the chosen interleaving depths (powers of 2), the output bytes from the interleaver always occupy distinct time slots when $N$ is odd. When $N$ is even, a dummy byte shall be added at the beginning of the codeword at the input to the interleaver. The resultant odd-length codeword is then convolutedly interleaved, and the dummy byte shall then be removed from the output of the interleaver. + +#### 7.6.4 Support of higher downstream bit rates with $S = 1/2$ (optional) + +With a rate of 4000 data frames per second and a maximum of 255 bytes (maximum RS codeword size) per data frame, the ADSL downstream line rate is limited to approximately 8 Mbit/s per latency path. The line rate limit can be increased to about 16 Mbit/s for the interleaved path by mapping two RS codewords into one FEC data frame (i.e. by using $S = 1/2$ in the interleaved path). $S = 1/2$ shall be used in the downstream direction only over bearer channel AS0. Support of $S = 1/2$ is optional. + +When the $K_I$ data bytes per interleaved mux data frame cannot be packed into one RS codeword, i.e. $K_I$ is such that $K_I + R > 255$ , the $K_I$ data bytes shall be split into two consecutive RS codewords. When $K_I$ is even, the first and second codeword have the same length $N_{I1} = N_{I2} = (K_I/2 + R_I)$ , otherwise the first codeword is one byte longer than the second, i.e. first codeword has $N_{I1} = (K_I + 1)/2 + R_I$ bytes, the second codeword has $N_{I2} = (K_I - 1)/2 + R_I$ bytes. For the FEC output data frame, $N_I = N_{I1} + N_{I2}$ , with $N_I < 511$ bytes. + +The convolutional interleaver requires all codewords to have the same odd length. To achieve the odd codeword length, insertion of a dummy (not transmitted) byte may be required. For $S = 1/2$ , the dummy byte addition to the first and/or second codeword at the input of the interleaver shall be as in Table 7-9. + +**Table 7-9/G.992.1 – Dummy byte insertion at interleaver input for $S = 1/2$** + +| $N_{Id1}$ | $N_{Id2}$ | Dummy Byte Insertion Action | +|-----------|-----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Odd | Odd | No action | +| Even | Even | Add one dummy byte at the beginning of both codewords | +| Odd | Even | Add one dummy byte at the beginning of the second codeword | +| Even | Odd | Add one dummy byte at the beginning of the first codeword and two dummy bytes at the beginning of the second codeword [the de-interleaver shall insert one dummy byte into the de-interleaver matrix on the first byte and the $(D + 1)$ th byte of the corresponding codeword to make the addressing work properly] | + +## 7.7 Tone ordering + +A DMT time-domain signal has a high peak-to-average ratio (its amplitude distribution is almost Gaussian), and large values may be clipped by the digital-to-analogue converter. The error signal caused by clipping can be considered as an additive negative impulse for the time sample that was clipped. The clipping error power is almost equally distributed across all tones in the symbol in which clipping occurs. Clipping is therefore most likely to cause errors on those tones that, in anticipation of a higher received SNR, have been assigned the largest number of bits (and therefore have the densest constellations). These occasional errors can be reliably corrected by the FEC coding if the tones with the largest number of bits have been assigned to the interleave buffer. + +The numbers of bits and the relative gains to be used for every tone shall be calculated in the ATU-R receiver, and sent back to the ATU-C according to a defined protocol (see 10.9.14). The pairs of numbers are typically stored, in ascending order of frequency or tone number $i$ , in a bit and gain table. + +The "tone-ordered" encoding shall first assign the $8 \times N_F$ bits from the fast data buffer (see 7.4) to the tones with the smallest number of bits assigned to them, and then the $8 \times N_I$ bits from the interleave data buffer to the remaining tones. + +All tones shall be encoded with the number of bits assigned to them; one tone may therefore have a mixture of bits from the fast and interleaved buffers. + +The ordered bit table $b'_i$ shall be based on the original bit table $b_i$ as follows: + +For $k = 0$ to 15 { + +    From the bit table, find the set of all $i$ with the number of bits per tone $b_i = k$ + +    Assign $b_i$ to the ordered bit allocation table in ascending order of $i$ + +} + +A complementary de-ordering procedure should be performed in the ATU-R receiver. It is not necessary, however, to send the results of the ordering process to the receiver because the bit table was originally generated in the ATU-R, and therefore that table has all the information necessary to perform the de-ordering. + +Figures 7-11 and 7-12 show an example of tone ordering and bit extraction (without and with trellis coding respectively) for a 6-tone DMT case, with $N_F = 1$ and $N_I = 1$ for simplicity. + +![A diagram showing SNR vs tone index with bit allocation, a list of tone ordering equations, and a data frame buffer diagram showing bit extraction from fast and interleaved buffers.](64aba6d3bacc69b7b90f08e02f2d5efe_img.jpg) + +**SNR vs tone index graph:** + +| Tone Index | Bit Allocation | +|------------|----------------| +| 0 | 2 bit | +| 1 | 3 bit | +| 2 | 6 bit | +| 3 | 3 bit | +| 4 | 2 bit | +| 5 | 0 bit | + +**Tone ordered:** + +- $b_0' = b_5 = 0$ +- $b_1' = b_0 = 2$ +- $b_2' = b_4 = 2$ +- $b_3' = b_1 = 3$ +- $b_4' = b_3 = 3$ +- $b_5' = b_2 = 6$ + +**Data frame buffer diagram:** + +The buffer is divided into two sections: **Fast data buffer** (bits $d_0$ to $d_7$ ) and **Interleaved data buffer** (bits $d_0$ to $d_7$ ). The **lsb** (least significant bit) is at the start of the fast buffer and the **msb** (most significant bit) is at the end of the interleaved buffer. + +Bit extraction mapping: + +- $b_0'$ → tone 5 (0 bit) +- $b_1'$ → tone 0 (2 bit) +- $b_2'$ → tone 4 (2 bit) +- $b_3'$ → tone 1 (3 bit) +- $b_4'$ → tone 3 (3 bit) +- $b_5'$ → tone 2 (6 bit) + +T1532460-99 + +A diagram showing SNR vs tone index with bit allocation, a list of tone ordering equations, and a data frame buffer diagram showing bit extraction from fast and interleaved buffers. + +**Figure 7-11/G.992.1 – Tone ordering and bit extraction example (without trellis coding)** + +![Figure 7-12/G.992.1 – Tone ordering and bit extraction example (with trellis coding). The figure consists of two parts. The top part is a graph of SNR vs. tone index (0 to 5). A smooth curve represents the SNR profile. Bars of different heights represent the bit allocation for each tone: tone 0 (3 bit), tone 1 (5 bit), tone 2 (7 bit), tone 3 (5 bit), tone 4 (3 bit), and tone 5 (0 bit). The bottom part shows the 'Data frame buffer' divided into 'Fast data buffer' (d0 to d7) and 'Interleaved data buffer' (d0 to d7). Arrows show the extraction of bits from these buffers to form tones: tone 5 (0 bit) from d0 of Fast buffer, tone 0 (3 bit) from d1 of Fast buffer, tone 4 (3 bit) from d2 of Fast buffer, tone 1 (5 bit) from d3-d7 of Fast buffer, tone 3 (5 bit) from d0 of Interleaved buffer, and tone 2 (7 bit) from d1-d7 of Interleaved buffer. A 'Tone ordered' list on the right defines the mapping: b0' = b5 = 0, b1' = b0 = 3, b2' = b4 = 3, b3' = b1 = 5, b4' = b3 = 5, b5' = b2 = 7. Bit extraction formulas are shown: b0' + b1' - 1 for tone 5, b2' + b3' - 3 for tone 4, and b4' + b5' - 3 for tone 2.](119006c9a930f46881484f2229d3b927_img.jpg) + +Figure 7-12/G.992.1 – Tone ordering and bit extraction example (with trellis coding). The figure consists of two parts. The top part is a graph of SNR vs. tone index (0 to 5). A smooth curve represents the SNR profile. Bars of different heights represent the bit allocation for each tone: tone 0 (3 bit), tone 1 (5 bit), tone 2 (7 bit), tone 3 (5 bit), tone 4 (3 bit), and tone 5 (0 bit). The bottom part shows the 'Data frame buffer' divided into 'Fast data buffer' (d0 to d7) and 'Interleaved data buffer' (d0 to d7). Arrows show the extraction of bits from these buffers to form tones: tone 5 (0 bit) from d0 of Fast buffer, tone 0 (3 bit) from d1 of Fast buffer, tone 4 (3 bit) from d2 of Fast buffer, tone 1 (5 bit) from d3-d7 of Fast buffer, tone 3 (5 bit) from d0 of Interleaved buffer, and tone 2 (7 bit) from d1-d7 of Interleaved buffer. A 'Tone ordered' list on the right defines the mapping: b0' = b5 = 0, b1' = b0 = 3, b2' = b4 = 3, b3' = b1 = 5, b4' = b3 = 5, b5' = b2 = 7. Bit extraction formulas are shown: b0' + b1' - 1 for tone 5, b2' + b3' - 3 for tone 4, and b4' + b5' - 3 for tone 2. + +Figure 7-12/G.992.1 – Tone ordering and bit extraction example (with trellis coding) + +## 7.8 Constellation encoder (trellis code version) + +Block processing of Wei's 16-state 4-dimensional trellis code is optional to improve system performance. An algorithmic constellation encoder shall be used to construct constellations with a maximum number of bits equal to $N_{\text{downmax}}$ , where $8 \leq N_{\text{downmax}} \leq 15$ . + +### 7.8.1 Bit extraction + +Data bytes from the data frame buffer shall be extracted according to a reordered bit allocation table $b'_i$ , least significant bit first. Because of the 4-dimensional nature of the code, the extraction is based on pairs of consecutive $b'_i$ , rather than on individual ones, as in the non-trellis-coded case. Furthermore, due to the constellation expansion associated with coding, the bit allocation table, $b'_i$ , specifies the number of coded bits per tone, which can be any integer from 2 to 15. Given a pair $(x, y)$ of consecutive $b'_i$ , $x + y - 1$ bits (reflecting a constellation expansion of 1 bit per 4 dimensions, or one half bit per tone) are extracted from the data frame buffer. These $z = x + y - 1$ bits $(t_z, t_{z-1}, \dots, t_1)$ are used to form the binary word $u$ as shown in Table 7-10. The tone ordering procedure ensures $x \leq y$ . Single-bit constellations are not allowed because they can be replaced by 2-bit constellations with the same average energy. Refer to 7.8.2 for the reason behind the special form of the word $u$ for the case $x = 0, y > 1$ . + +**Table 7-10/G.992.1 – Forming the binary word $u$** + +| Condition | Binary word/comment | +|---------------------------------------------------------------------|----------------------------------------------------------| +| $x > 1, y > 1$ | $u = (t_z, t_{z-1}, \dots, t_1)$ | +| $x = 1, y \geq 1$ | Condition not allowed | +| $x = 0, y > 1$ | $u = (t_z, t_{z-1}, \dots, t_2, 0, t_1, 0)$ | +| $x = 0, y = 0$ | Bit extraction not necessary, no message bits being sent | +| $x = 0, y = 1$ | Condition not allowed | +| NOTE – $t_1$ is the first bit extracted from the data frame buffer. | | + +The last two 4-dimensional symbols in the DMT symbol shall be chosen to force the convolutional encoder state to the zero state. For each of these symbols, the 2 LSBs of $u$ are predetermined, and only $(x + y - 3)$ bits shall be extracted from the data frame buffer and shall be allocated to $t_3, t_4, \dots, t_z$ . + +### 7.8.2 Bit conversion + +The binary word $u = (u_z', u_{z-1}, \dots, u_1)$ determines two binary words $v = (v_{z-y}, \dots, v_0)$ and $w = (w_{y-1}, \dots, w_0)$ , which are used to look up two constellation points in the encoder constellation table. For the usual case of $x > 1$ and $y > 1$ , $z' = z = x + y - 1$ , and $v$ and $w$ contain $x$ and $y$ bits respectively. For the special case of $x = 0$ and $y > 1$ , $z' = z + 2 = y + 1$ , $v = (v_1, v_0) = 0$ and $w = (w_{y-1}, \dots, w_0)$ . The bits $(u_3, u_2, u_1)$ determine $(v_1, v_0)$ and $(w_1, w_0)$ according to Figure 7-13. + +The convolutional encoder shown in Figure 7-13 is a systematic encoder (i.e. $u_1$ and $u_2$ are passed through unchanged) as shown in Figure 7-14. The convolutional encoder state $(S_3, S_2, S_1, S_0)$ is used to label the states of the trellis shown in Figure 7-16. At the beginning of a DMT symbol period, the convolutional encoder state is initialized to $(0, 0, 0, 0)$ . + +The remaining bits of $v$ and $w$ are obtained from the less significant and more significant parts of $(u_z', u_{z-1}, \dots, u_4)$ , respectively. When $x > 1$ and $y > 1$ , $v = (u_{z-y+2}, u_{z-y+1}, \dots, u_4, v_1, v_0)$ and $w = (u_z, u_{z-1}, \dots, u_{z-y+3}, w_1, w_0)$ . When $x = 0$ , the bit extraction and conversion algorithms have been judiciously designed so that $v_1 = v_0 = 0$ . The binary word $v$ is input first to the constellation encoder, and then the binary word $w$ . + +In order to force the final state to the zero state $(0, 0, 0, 0)$ , the 2 LSBs $u_1$ and $u_2$ of the final two 4-dimensional symbols in the DMT symbol are constrained to $u_1 = S_1 \oplus S_3$ , and $u_2 = S_2$ . + +### 7.8.3 Coset partition and trellis diagram + +In a trellis code modulation system, the expanded constellation is labelled and partitioned into subsets ("cosets") using a technique called mapping by set-partitioning. The 4-dimensional cosets in Wei's code can each be written as the union of two Cartesian products of two 2-dimensional cosets. For example, $C_4^0 = (C_2^0 \times C_2^1) \cup (C_2^2 \times C_2^3)$ . The four constituent 2-dimensional cosets, denoted by $C_2^0, C_2^1, C_2^2, C_2^3$ , are shown in Figure 7-15. + +The encoding algorithm ensures that the two least significant bits of a constellation point comprise the index $i$ of the 2-dimensional coset $C_2^i$ in which the constellation point lies. The bits $(v_1, v_0)$ and $(w_1, w_0)$ are in fact the binary representations of this index. + +The three bits $(u_2, u_1, u_0)$ are used to select one of the eight possible 4-dimensional cosets. The eight cosets are labelled $C_4^i$ where $i$ is the integer with binary representation $(u_2, u_1, u_0)$ . The additional bit $u_3$ (see Figure 7-13) determines which one of the two Cartesian products of 2-dimensional cosets in + +the 4-dimensional coset is chosen. The relationship is shown in Table 7-11. The bits ( $v_1, v_0$ ) and ( $w_1, w_0$ ) are computed from ( $u_3, u_2, u_1, u_0$ ) using the linear equations given in Figure 7-13. + +![Diagram of the conversion of u to v and w using a Convolutional Encoder.](7d929ba1b7d09ea8e00b9e7abbbe50c9_img.jpg) + +This diagram illustrates the conversion of input bits $u$ to output bits $v$ and $w$ . The input sequence $u$ consists of bits $u_{z'}, u_{z'-1}, \dots, u_{z'-y+3}, u_{z'-y+2}, u_{z'-y+1}, \dots, u_4, u_3, u_2, u_1$ . The output sequence $v$ consists of bits $w_{y-1}, w_{y-2}, \dots, w_2, v_{z'-y}, v_{z'-y-1}, \dots, v_2, v_1, v_0$ . The output sequence $w$ consists of bits $w_1, w_0$ . A block labeled "Convolutional Encoder" takes $u_1, u_2, u_3$ as input and produces $u_0, u_1, u_2$ as output. These outputs are then processed by a logic block containing the following equations: + +$$\begin{aligned} v_1 &= u_1 \oplus u_3 \\ v_0 &= u_3 \\ w_1 &= u_0 \oplus u_1 \\ &\oplus u_2 \oplus u_3 \\ w_0 &= u_2 \oplus u_3 \end{aligned}$$ + +The identifier T1532480-99 is shown at the bottom right of the logic block. + +Diagram of the conversion of u to v and w using a Convolutional Encoder. + +Figure 7-13/G.992.1 – Conversion of $u$ to $v$ and $w$ + +![Diagram of the finite state machine for Wei's encoder.](3337af75dfee8af7687b4f49914d6c93_img.jpg) + +This diagram shows the finite state machine (FSM) for Wei's encoder. The input sequence $u$ consists of bits $u_2, u_1, u_0$ . The state sequence $s$ consists of bits $s_2, s_1, s_3, s_0$ . The FSM is implemented using four delay elements (D) and two XOR gates. The state $s_2$ is the output of the first delay element, $s_1$ is the output of the second, $s_3$ is the output of the third, and $s_0$ is the output of the fourth. The XOR gates are used to compute the next state bits from the current state bits and the input bits. The identifier T1532490-99 is shown at the bottom right of the diagram. + +Diagram of the finite state machine for Wei's encoder. + +Figure 7-14/G.992.1 – Finite state machine for Wei's encoder + +![A diagram showing a 2D coordinate system with x and y axes. The origin is at the center. The top-left quadrant contains the sequence of numbers: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. The top-right quadrant contains: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. The bottom-left quadrant contains: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. The bottom-right quadrant contains: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. Below the x-axis on the right side, there is a label 'T1532500-99'.](1dea2e515f706e8044ae79339efaa36c_img.jpg) + +A diagram showing a 2D coordinate system with x and y axes. The origin is at the center. The top-left quadrant contains the sequence of numbers: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. The top-right quadrant contains: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. The bottom-left quadrant contains: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. The bottom-right quadrant contains: 1 3 1 3, 0 2 0 2, 1 3 1 3, 0 2 0 2. Below the x-axis on the right side, there is a label 'T1532500-99'. + +Figure 7-15/G.992.1 – Convolutional encoder + +Table 7-11/G.992.1 – Relation between 4-dimensional and 2-dimensional cosets + +| 4-D coset | $u_3$ | $u_2$ | $u_1$ | $u_0$ | $v_1$ | $v_0$ | $w_1$ | $w_0$ | 2-D cosets | +|-----------|-------|-------|-------|-------|-------|-------|-------|-------|----------------------------------------------| +| $C_4^0$ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | $C_2^0 \times C_2^0$
$C_2^3 \times C_2^3$ | +| | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | | +| $C_4^4$ | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | $C_2^0 \times C_2^3$
$C_2^3 \times C_2^0$ | +| | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | | +| $C_4^2$ | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | $C_2^2 \times C_2^2$
$C_2^1 \times C_2^1$ | +| | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | | +| $C_4^6$ | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | $C_2^2 \times C_2^1$
$C_2^1 \times C_2^2$ | +| | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | | +| $C_4^1$ | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | $C_2^0 \times C_2^2$
$C_2^3 \times C_2^1$ | +| | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | | +| $C_4^5$ | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | $C_2^0 \times C_2^1$
$C_2^3 \times C_2^2$ | +| | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | | +| $C_4^3$ | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | $C_2^2 \times C_2^0$
$C_2^1 \times C_2^3$ | +| | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | | +| $C_4^7$ | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | $C_2^2 \times C_2^3$
$C_2^1 \times C_2^0$ | +| | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | | + +![Trellis diagram showing state transitions between two columns of 16 states each. The left column is labeled (S3, S2, S1, S0) and the right column is labeled (T3, T2, T1, T0). Transitions are shown as lines connecting states in adjacent columns, forming a dense web. The states are indexed 0-15, with 0-9 being numerical and A-F being hexadecimal. Each state has a 4-dimensional coset label next to it. The diagram is labeled T1532510-99 at the bottom right.](c2c4e63ebb9afc1ab64e39a159890e0f_img.jpg) + +The diagram illustrates a trellis structure for a finite state machine. It consists of two vertical columns of 16 nodes each. The left column represents current states $S = (S_3, S_2, S_1, S_0)$ and the right column represents next states $T = (T_3, T_2, T_1, T_0)$ . The nodes are arranged vertically and indexed from 0 to 15 (0-9, A-F). Each state has an associated 4-dimensional coset label. The mapping is as follows: + +| Current State (S) | Coset Label (Left) | Next State (T) | Coset Label (Right) | +|-------------------|--------------------|----------------|---------------------| +| 0 | 0 2 4 6 | 0 | 0 4 2 6 | +| 1 | 1 3 5 7 | 1 | 2 6 0 4 | +| 2 | 2 0 6 4 | 2 | 4 0 6 2 | +| 3 | 3 1 7 5 | 3 | 6 2 4 0 | +| 4 | 4 6 0 2 | 4 | 1 5 3 7 | +| 5 | 5 7 1 3 | 5 | 3 7 1 5 | +| 6 | 6 4 2 0 | 6 | 5 1 7 3 | +| 7 | 7 5 3 1 | 7 | 7 3 5 1 | +| 8 | 2 0 6 4 | 8 | 2 6 0 4 | +| 9 | 3 1 7 5 | 9 | 0 4 2 6 | +| A | 0 2 4 6 | A | 6 2 4 0 | +| B | 1 3 5 7 | B | 4 0 6 2 | +| C | 6 4 2 0 | C | 3 7 1 5 | +| D | 7 5 3 1 | D | 1 5 3 7 | +| E | 4 6 0 2 | E | 7 3 5 1 | +| F | 5 7 1 3 | F | 5 1 7 3 | + +Transitions are represented by lines connecting nodes in the left column to nodes in the right column. A small label 'T1532510-99' is located at the bottom right of the diagram. + +Trellis diagram showing state transitions between two columns of 16 states each. The left column is labeled (S3, S2, S1, S0) and the right column is labeled (T3, T2, T1, T0). Transitions are shown as lines connecting states in adjacent columns, forming a dense web. The states are indexed 0-15, with 0-9 being numerical and A-F being hexadecimal. Each state has a 4-dimensional coset label next to it. The diagram is labeled T1532510-99 at the bottom right. + +**Figure 7-16/G.992.1 – Trellis diagram** + +Figure 7-16 shows the trellis diagram based on the finite state machine in Figure 7-14, and the one-to-one correspondence between $(u_2, u_1, u_0)$ and the 4-dimensional cosets. In the figures, $S = (S_3, S_2, S_1, S_0)$ represents the current state, while $T = (T_3, T_2, T_1, T_0)$ represents the next state in the finite state machine. $S$ is connected to $T$ in the constellation diagram by a branch determined by the values of $u_2$ and $u_1$ . The branch is labelled with the 4-dimensional coset specified by the values of $u_2, u_1$ (and $u_0 = S_0$ , see Figure 7-15). To make the constellation diagram more readable, the indices of the 4-dimensional coset labels are listed next to the starting and end points of the + +branches, rather than on the branches themselves. The leftmost label corresponds to the uppermost branch for each state. The constellation diagram is used when decoding the trellis code by the Viterbi algorithm. + +### 7.8.4 Constellation encoder + +For a given subcarrier, the encoder shall select an odd-integer point $(X, Y)$ from the square-grid constellation based on the $b$ bits of either $\{v_{b-1}, v_{b-2}, \dots, v_1, v_0\}$ or $\{w_{b-1}, w_{b-2}, \dots, w_1, w_0\}$ . For convenience of description, these $b$ bits are identified with an integer label whose binary representation is $(v_{b-1}, v_{b-2}, \dots, v_1, v_0)$ , but the same encoding rules apply also to the $w$ vector. For example, for $b = 2$ , the four constellation points are labelled 0, 1, 2, 3 corresponding to $(v_1, v_0) = (0, 0), (0, 1), (1, 0), (1, 1)$ , respectively. + +NOTE – $v_0$ is the first bit extracted from the buffer. + +#### 7.8.4.1 Even values of $b$ + +For even values of $b$ , the integer values $X$ and $Y$ of the constellation point $(X, Y)$ shall be determined from the $b$ bits $\{v_{b-1}, v_{b-2}, \dots, v_1, v_0\}$ as follows. $X$ and $Y$ are the odd integers with two-complement binary representations $(v_{b-1}, v_{b-3}, \dots, v_1, 1)$ and $(v_{b-2}, v_{b-4}, \dots, v_0, 1)$ , respectively. The most significant bits (MSBs), $v_{b-1}$ and $v_{b-2}$ , are the sign bits for $X$ and $Y$ , respectively. + +Figure 7-17 shows example constellations for $b = 2$ and $b = 4$ . + +![Figure 7-17 shows two constellation diagrams. The left diagram for b=2 shows four points: 0 at (1,1), 1 at (1,-1), 2 at (-1,1), and 3 at (-1,-1). The right diagram for b=4 shows 16 points arranged in a 4x4 grid with coordinates from -3 to 3. Labels are placed in a specific order: top row (9, 11, 1, 3), second row (8, 10, 0, 2), third row (-3, -1, 1, 3), fourth row (13, 15, 5, 7), fifth row (12, 14, 4, 6). Axes are marked with -3, -1, 1, 3.](c9c3809709886a056c616a3aaece0c6d_img.jpg) + +Figure 7-17 shows two constellation diagrams. The left diagram for b=2 shows four points: 0 at (1,1), 1 at (1,-1), 2 at (-1,1), and 3 at (-1,-1). The right diagram for b=4 shows 16 points arranged in a 4x4 grid with coordinates from -3 to 3. Labels are placed in a specific order: top row (9, 11, 1, 3), second row (8, 10, 0, 2), third row (-3, -1, 1, 3), fourth row (13, 15, 5, 7), fifth row (12, 14, 4, 6). Axes are marked with -3, -1, 1, 3. + +NOTE – The values of $X$ and $Y$ shown represent the output of the constellation encoder. These values require appropriate scaling such that: + +- 1) all constellations regardless of size represent the same RMS energy; and +- 2) by the fine gain scaling (7.10) before modulation by the IDFT (7.11.2). + +**Figure 7-17/G.992.1 – Constellation labels for $b = 2$ and $b = 4$** + +The 4-bit constellation can be obtained from the 2-bit constellation by replacing each label $n$ by a $2 \times 2$ block of labels as shown in Figure 7-18. + +| | | +|----------|----------| +| $4n + 1$ | $4n + 3$ | +| $4n$ | $4n + 2$ | + +**Figure 7-18/G.992.1 – Expansion of point $n$ into the next larger square constellation** + +The same procedure can be used to construct the larger even-bit constellations recursively. + +The constellations obtained for even values of $b$ are square in shape. The least significant bits $\{v_1, v_0\}$ represent the coset labelling of the constituent 2-dimensional cosets used in the 4-dimensional Wei trellis code. + +#### 7.8.4.2 Odd values of $b$ , $b = 3$ + +Figure 7-19 shows the constellation for the case $b = 3$ . + +![Figure 7-19/G.992.1 – Constellation labels for b = 3. The diagram shows a 2D coordinate system with X and Y axes. The X-axis has tick marks at -3, -1, 1, and 3. The Y-axis has tick marks at -3, -1, 1, and 3. The constellation points are labeled as follows: 0 at (0,0), 1 at (1,0), 2 at (0,1), 3 at (1,1), 4 at (-1,0), 5 at (0,3), 6 at (0,-3), and 7 at (3,0). A small label 'T1532530-99' is present at the bottom right of the diagram.](fcdcb5991d671cadf547dd3fbfe13486_img.jpg) + +Figure 7-19/G.992.1 – Constellation labels for b = 3. The diagram shows a 2D coordinate system with X and Y axes. The X-axis has tick marks at -3, -1, 1, and 3. The Y-axis has tick marks at -3, -1, 1, and 3. The constellation points are labeled as follows: 0 at (0,0), 1 at (1,0), 2 at (0,1), 3 at (1,1), 4 at (-1,0), 5 at (0,3), 6 at (0,-3), and 7 at (3,0). A small label 'T1532530-99' is present at the bottom right of the diagram. + +NOTE – The values of $X$ and $Y$ shown represent the output of the constellation encoder. These values require appropriate scaling such that: + +- 1) all constellations regardless of size represent the same RMS energy; and +- 2) by the fine gain scaling (7.10) before modulation by the IDFT (7.11.2). + +**Figure 7-19/G.992.1 – Constellation labels for $b = 3$** + +#### 7.8.4.3 Odd values of $b$ , $b > 3$ + +If $b$ is odd and greater than 3, the 2 MSBs of $X$ and the 2 MSBs of $Y$ are determined by the 5 MSBs of the $b$ bits. Let $c = (b + 1)/2$ , then $X$ and $Y$ have the two-complement binary representations $(X_c, X_{c-1}, v_{b-4}, v_{b-6}, \dots, v_3, v_1, 1)$ and $(Y_c, Y_{c-1}, v_{b-5}, v_{b-7}, v_{b-9}, \dots, v_2, v_0, 1)$ , where $X_c$ and $Y_c$ are the sign bits of $X$ and $Y$ respectively. The relationship between $X_c, X_{c-1}, Y_c, Y_{c-1}$ and $v_{b-1}, v_{b-2}, \dots, v_{b-5}$ is shown in Table 7-12. + +**Table 7-12/G.992.1 – Determining the top 2 bits of *X* and *Y*** + +| Vb-1, Vb-2, ..., Vb-5 | Xc, Xc-1 | Yc, Yc-1 | +|---------------------------------------------------------------|---------------------------------------|---------------------------------------| +| 0 0 0 0 0 | 0 0 | 0 0 | +| 0 0 0 0 1 | 0 0 | 0 0 | +| 0 0 0 1 0 | 0 0 | 0 0 | +| 0 0 0 1 1 | 0 0 | 0 0 | +| 0 0 1 0 0 | 0 0 | 1 1 | +| 0 0 1 0 1 | 0 0 | 1 1 | +| 0 0 1 1 0 | 0 0 | 1 1 | +| 0 0 1 1 1 | 0 0 | 1 1 | +| 0 1 0 0 0 | 1 1 | 0 0 | +| 0 1 0 0 1 | 1 1 | 0 0 | +| 0 1 0 1 0 | 1 1 | 0 0 | +| 0 1 0 1 1 | 1 1 | 0 0 | +| 0 1 1 0 0 | 1 1 | 1 1 | +| 0 1 1 0 1 | 1 1 | 1 1 | +| 0 1 1 1 0 | 1 1 | 1 1 | +| 0 1 1 1 1 | 1 1 | 1 1 | +| 1 0 0 0 0 | 0 1 | 0 0 | +| 1 0 0 0 1 | 0 1 | 0 0 | +| 1 0 0 1 0 | 1 0 | 0 0 | +| 1 0 0 1 1 | 1 0 | 0 0 | +| 1 0 1 0 0 | 0 0 | 0 1 | +| 1 0 1 0 1 | 0 0 | 1 0 | +| 1 0 1 1 0 | 0 0 | 0 1 | +| 1 0 1 1 1 | 0 0 | 1 0 | +| 1 1 0 0 0 | 1 1 | 0 1 | +| 1 1 0 0 1 | 1 1 | 1 0 | +| 1 1 0 1 0 | 1 1 | 0 1 | +| 1 1 0 1 1 | 1 1 | 1 0 | +| 1 1 1 0 0 | 0 1 | 1 1 | +| 1 1 1 0 1 | 0 1 | 1 1 | +| 1 1 1 1 0 | 1 0 | 1 1 | +| 1 1 1 1 1 | 1 0 | 1 1 | + +Figure 7-20 shows the constellation for the case $b = 5$ . + +| | | | | | +|-------|----|--|----|----| +| 24 | 26 | | 20 | 22 | +| 19 | 09 | | 01 | 03 | +| 18 | 08 | | 00 | 02 | +|
| | | | | +| 31 | 13 | | 05 | 07 | +| 30 | 12 | | 04 | 06 | +| 25 | 27 | | 21 | 23 | + +NOTE 1 – As with Figure 7-19, the $X$ and $Y$ values are on a $\pm 1, \pm 3, \dots$ grid. + +NOTE 2 – The values of $X$ and $Y$ shown represent the output of the constellation encoder. These values require appropriate scaling such that: + +- 1) all constellations regardless of size represent the same RMS energy; and +- 2) by the fine gain scaling (7.10) before modulation by the IDFT (7.11.2). + +**Figure 7-20/G.992.1 – Constellation labels for $b = 5$** + +The 7-bit constellation shall be obtained from the 5-bit constellation by replacing each label $n$ by the $2 \times 2$ block of labels as shown in Figure 7-18. + +Again, the same procedure shall be used to construct the larger odd-bit constellations recursively. Note also that the least significant bits $\{v_1, v_0\}$ represent the coset labelling of the constituent 2-dimensional cosets used in the 4-dimensional Wei trellis code. + +## 7.9 Constellation encoder – No trellis coding + +An algorithmic constellation encoder shall be used to construct constellations with a maximum number of bits equal to $N_{\text{downmax}}$ , where $8 \leq N_{\text{downmax}} \leq 15$ . The constellation encoder shall not use trellis coding with this option. + +### 7.9.1 Bit extraction + +Data bits from the frame data buffer shall be extracted according to a reordered bit allocation table $b'_i$ , least significant bit first. The number of bits per tone, $b'_i$ , can take any non-negative integer values not exceeding $N_{\text{downmax}}$ , and greater than 1. For a given tone $b = b'_i$ bits are extracted from the data frame buffer, and these bits form a binary word $\{v_{b-1}, v_{b-2}, \dots, v_1, v_0\}$ . The first bit extracted shall be $v_0$ , the LSB. + +### 7.9.2 Constellation encoder + +The constellation encoder requirements are as specified in 7.8.4. + +## 7.10 Gain scaling + +For the transmission of data symbols gain scaling, $g_i$ , shall be applied as requested by the ATU-R (see 10.9.14 and A.1.2.1 or B.1.3.1) and possibly updated during Showtime via the bit swap procedure. Only values of $g_i$ equal to zero or within a range of approximately 0.19 to 1.33 (i.e. $-14.5$ dB to $+2.5$ dB) may be used. For the transmission of synchronization symbols, no gain scaling shall be applied as defined in Annexes A, B and C. + +Each constellation point, $(X_i, Y_i)$ , i.e. complex number $X_i + jY_i$ , output from the encoder is multiplied by $g_i$ : + +$$Z_i = g_i (X_i + jY_i) \quad (7-20)$$ + +NOTE – The $g_i$ define a scaling of the root mean square (rms) subcarrier levels relative to those used in C-MEDLEY (see 10.6.6). They are independent of any methods that manufacturers may use to simplify implementation (e.g. constellation nesting). + +## 7.11 Modulation + +### 7.11.1 Subcarriers + +The frequency spacing, $\Delta f$ , between subcarriers is 4.3125 kHz, with a tolerance of $\pm 50$ ppm. + +#### 7.11.1.1 Data subcarriers + +The channel analysis signal defined in 10.6.6 allows for a maximum of 255 carriers (at frequencies $n\Delta f$ , $n = 1$ to 255) to be used. The lower limit of $n$ depends on both the duplexing and service options selected. For example, for ADSL above POTS service option as defined in Annex A, if overlapped spectrum is used to separate downstream and upstream signals, then the lower limit on $n$ is determined by the POTS splitting filters; if frequency-division multiplexing (FDM) is used the lower limit is set by the downstream-upstream separation filters. + +In all cases the cut-off frequencies of these filters are completely at the discretion of the manufacturer, and the range of usable $n$ is determined during the channel estimation. + +#### 7.11.1.2 Pilot + +Carrier # $N_{\text{pilot}}$ ( $f_{\text{pilot}} = 4.3125 \times N_{\text{pilot}}$ kHz) shall be reserved for a pilot; that is $b(N_{\text{pilot}}) = 0$ and $g(N_{\text{pilot}}) = g_{\text{sync}}$ . + +$N_{\text{pilot}}$ and $g_{\text{sync}}$ are defined in Annexes A, B and C. The value $g_{\text{sync}}$ represents the gain scaling applied to the sync symbol. (See 10.4.2.) + +The data modulated onto the pilot subcarrier shall be a constant $\{0,0\}$ . Use of this pilot allows resolution of sample timing in a receiver modulo-8 samples. Therefore a gross timing error that is an integer multiple of eight samples could still persist after a micro-interruption (e.g. a temporary short-circuit, open circuit or severe line hit); correction of such timing errors is made possible by the use of the synchronization symbol defined in 7.11.3. + +#### 7.11.1.3 Nyquist frequency + +The carrier at the Nyquist frequency (#256) shall not be used for user data and shall be real valued; other possible uses are for further study. + +#### 7.11.1.4 DC + +The carrier at DC (#0) shall not be used, and shall contain no energy. + +### 7.11.2 Modulation by the inverse discrete Fourier transform (IDFT) + +The modulating transform defines the relationship between the 512 real values $x_n$ and the $Z_i$ : + +$$x_n = \sum_{i=0}^{511} \exp\left(\frac{j\pi ni}{256}\right) Z_i \quad \text{for } n = 0 \text{ to } 511 \quad (7-21)$$ + +The constellation encoder and gain scaling generate only 255 complex values of $Z_i$ . In order to generate real values of $x_n$ , the input values (255 complex values plus zero at DC and one real value for Nyquist if used) shall be augmented so that the vector $Z$ has Hermitian symmetry. That is, + +$$Z_i = \text{conj}(Z'_{512-i}) \quad \text{for } i = 257 \text{ to } 511 \quad (7-22)$$ + +### 7.11.3 Synchronization symbol + +The synchronization symbol permits recovery of the frame boundary after micro-interruptions that might otherwise force retraining. + +The data symbol rate, $f_{\text{symb}} = 4$ kHz, the carrier separation, $\Delta f = 4.3125$ kHz, and the IDFT size, $N = 512$ , are such that a cyclic prefix of 40 samples could be used. That is, + +$$(512 + 40) \times 4.0 = 512 \times 4.3125 = 2208 \quad (7-23)$$ + +The cyclic prefix shall, however, be shortened to 32 samples, and a synchronization symbol (with a nominal length of 544 samples) is inserted after every 68 data symbols. That is, + +$$(512 + 32) \times 69 = (512 + 40) \times 68 \quad (7-24)$$ + +The data pattern used in the synchronization symbol shall be the pseudo-random sequence PRD, ( $d_n$ , for $n = 1$ to 512) defined by: + +$$d_n = 1 \quad \text{for } n = 1 \text{ to } 9 \quad (7-25)$$ + +$$d_n = d_{n-4} \oplus d_{n-9} \quad \text{for } n = 10 \text{ to } 512 \quad (7-26)$$ + +The first pair of bits ( $d_1$ and $d_2$ ) shall be used for the DC and Nyquist subcarriers (the power assigned to them is zero, so the bits are effectively ignored); the first and second bits of subsequent pairs are then used to define the $X_i$ and $Y_i$ for $i = 1$ to 255 as shown in Table 7-13. + +**Table 7-13/G.992.1 – Mapping of two data bits into a 4-QAM constellation** + +| $d_{2i+1}, d_{2i+2}$ | Decimal label (Note) | $X_i, Y_i$ | +|----------------------|----------------------|------------| +| 0 0 | 0 | + + | +| 0 1 | 1 | + - | +| 1 0 | 2 | - + | +| 1 1 | 3 | - - | + +NOTE – This labelling is different from the mapping in Figure 7-17 where $d_{2i+1}$ would be considered the first and least significant bit. + +The period of the PRD is only 511 bits, so $d_{512}$ shall be equal to $d_1$ . + +The $d_1$ - $d_9$ shall be re-initialized for each synchronization symbol, so each symbol uses the same data. Bits 129 and 130, which modulate the pilot carrier, shall be overwritten by {0,0}: generating the {+,+} constellation. + +The minimum set of subcarriers to be used is the set used for data transmission (i.e. those for which $b_i > 0$ ); subcarriers for which $b_i = 0$ may be used at a reduced PSD as defined in transmit PSD paragraphs of Annexes A, B and C. The data modulated onto each subcarrier shall be as defined above; it shall not depend on which subcarriers are used. + +### 7.11.4 Inverse synchronization symbol (Annex C only) + +For Annex C, see C.4.7.1. + +## 7.12 Cyclic prefix + +The last 32 samples of the output of the IDFT ( $x_n$ for $n = 480$ to $511$ ) shall be prepended to the block of 512 samples and read out to the digital-to-analogue converter (DAC) in sequence. That is, the subscripts, $n$ , of the DAC samples in sequence are $480 \dots 511, 0 \dots 511$ . + +The cyclic prefix shall be used for all symbols beginning with the C-RATES1 segment of the initialization sequence, as defined in 10.6.2. + +## 7.13 Transmitter dynamic range + +The transmitter includes all analogue transmitter functions: the D/A converter, the anti-aliasing filter, the hybrid circuitry, and the high-pass part of the POTS or ISDN splitter. The transmitted signal shall conform to the frequency requirements as described in 7.11.1 for frequency spacing. + +### 7.13.1 Maximum clipping rate + +The maximum output signal of the transmitter shall be such that the signal shall be clipped no more than 0.00001% of the time. + +### 7.13.2 Noise/distortion floor + +The signal-to-noise plus distortion ratio of the transmitted signal in a given subcarrier is specified as the ratio of the rms value of the tone in that subcarrier to the rms sum of all the non-tone signals in the 4.3125 kHz frequency band centered on the subcarrier frequency. This ratio is measured for each subcarrier used for transmission using a MultiTone Power Ratio (MTPR) test as shown in Figure 7-21. + +![Figure 7-21/G.992.1 – MTPR test. A graph showing power levels (dBm per subcarrier) versus frequency. It depicts a comb of tones with one tone suppressed, and a non-linear distortion component indicated by a dashed line.](8dd8ccefcffbf4756cee60d026dd30de_img.jpg) + +The figure is a graph with 'dBm per subcarrier' on the vertical axis and 'Frequency' on the horizontal axis. It shows a series of vertical lines representing tones. A bracket below the horizontal axis spans across these tones and is labeled 'A comb of $\Delta f$ -spaced tones with one tone suppressed'. One of the tones is missing, creating a gap. A dashed vertical line is drawn in this gap, with an arrow pointing to it from the label 'Non-linear distortion component'. In the bottom right corner of the graph area, there is a small label 'T1532540-99'. + +Figure 7-21/G.992.1 – MTPR test. A graph showing power levels (dBm per subcarrier) versus frequency. It depicts a comb of tones with one tone suppressed, and a non-linear distortion component indicated by a dashed line. + +**Figure 7-21/G.992.1 – MTPR test** + +Over the transmission frequency band, the MTPR of the transmitter in any subcarrier shall be no less than $(3N_{\text{downi}} + 20)$ dB, where $N_{\text{downi}}$ is defined as the size of the constellation (in bits) to be used on subcarrier $i$ . The minimum transmitter MTPR shall be at least 38 dB (corresponding to an $N_{\text{downi}}$ of 6) for any subcarrier. + +NOTE – Signals transmitted during normal initialization and data transmission cannot be used for this test because the DMT symbols have a cyclic prefix appended, and the PSD of a non-repetitive signal does not have nulls at any subcarrier frequencies. A gated FFT-based analyser could be used, but this would measure both the non-linear distortion and the linear distortion introduced by the transmit filter. Therefore this test will require that the transmitter be programmed with special software, probably to be used during development only. The subject of an MTPR test that can be applied to a production modem is for further study. + +#### **7.14 ATU-C Downstream Transmitter spectral masks** + +Spectral masks for the three service options are defined in Annexes A, B and C. + +For Annex A, see A.1.2 and A.1.3. + +For Annex B, see B.1.3. + +For Annex C, see C.4.8. + +#### **7.15 Dual Bitmapping and Rate Conversion (Annex C only)** + +For Annex C, see C.4.4. + +#### **7.16 FEXT Bitmapping (Annex C only)** + +For Annex C, see C.4.5. + +### **8 ATU-R Functional Characteristics** + +An ATU-R may support STM transmission or ATM transmission or both. If STM is supported, it shall be as defined in 8.1. If ATM is supported, it shall be as defined in 8.2. + +Framing modes that shall be supported depend upon the ATU-R being configured for either STM or ATM transport, and are defined in 8.1.4 and 8.2.3 respectively. If framing mode $k$ is supported, then modes $k - 1, \dots, 0$ shall also be supported. + +During initialization, the ATU-C and ATU-R shall indicate a framing mode number 0, 1, 2 or 3 which they intend to use. The lowest indicated framing mode shall be used (see 10.6.4 and 10.7.6). + +An ATU-R may support reconstruction of a Network Timing Reference (NTR) from the downstream indicator bits. + +#### **8.1 STM Transmission Protocol Specific functionalities** + +##### **8.1.1 ATU-R input and output T interfaces for STM transport** + +The functional data interfaces at the ATU-R are shown in Figure 8-1. Output interfaces for the high-speed downstream simplex bearer channels are designated AS0 through AS3; input-output interfaces for the duplex bearer channels are designated LS0 through LS2. There may also be a functional interface to transport operations, administration and maintenance (OAM) indicators from the CI to the ATU-R; this interface may physically be combined with the LS0 interface. + +The data rates of the input and output data interfaces at the ATU-R for the default configurations are specified in 6.1. + +![Diagram of ATU-R functional interfaces for STM transport at the T-R reference point. The diagram shows an ATU-R block on the left connected to a 'twisted pair' and a 'STM layer and interface to Service Modules' block on the right. A vertical dashed line represents the T-R reference point. Between the ATU-R and the STM layer, several channels are shown: AS0 (n0 x 32 kbit/s), AS1 (n1 x 32 kbit/s), AS2 (n2 x 32 kbit/s), and AS3 (n3 x 32 kbit/s) are simplex channels with arrows pointing right (dotted lines). LS0 ('C'; 16 or m0 x 32 kbit/s), LS1 (m1 x 32 kbit/s), and LS2 (m2 x 32 kbit/s) are duplex channels with arrows pointing both left and right (dotted lines). NTR and 'Operations, administration, maintenance and control' are also shown with arrows pointing right (dotted lines). The label 'T-R' is at the bottom center.](af6c3f383ddc0c142cdd7e186cc78199_img.jpg) + +Diagram of ATU-R functional interfaces for STM transport at the T-R reference point. The diagram shows an ATU-R block on the left connected to a 'twisted pair' and a 'STM layer and interface to Service Modules' block on the right. A vertical dashed line represents the T-R reference point. Between the ATU-R and the STM layer, several channels are shown: AS0 (n0 x 32 kbit/s), AS1 (n1 x 32 kbit/s), AS2 (n2 x 32 kbit/s), and AS3 (n3 x 32 kbit/s) are simplex channels with arrows pointing right (dotted lines). LS0 ('C'; 16 or m0 x 32 kbit/s), LS1 (m1 x 32 kbit/s), and LS2 (m2 x 32 kbit/s) are duplex channels with arrows pointing both left and right (dotted lines). NTR and 'Operations, administration, maintenance and control' are also shown with arrows pointing right (dotted lines). The label 'T-R' is at the bottom center. + +NOTE – Optional bearer channels (both duplex and simplex) and features are shown with dotted lines. + +**Figure 8-1/G.992.1 – ATU-R functional interfaces for STM transport at the T-R reference point** + +### 8.1.2 Downstream simplex channels – Transceiver bit rates + +The simplex channels are transported in the downstream direction only; therefore their data interfaces at the ATU-R operate only as outputs. The rates are the same as those for the ATU-C transmitter, as specified in 6.1. + +### 8.1.3 Duplex channels – Transceiver bit rates + +The duplex channels are transported in both directions, so the ATU-R shall provide both input and output data interfaces. The rates are the same as for the ATU-C, as specified in 6.1. + +### 8.1.4 Framing Structure for STM transport + +An ATU-R configured for STM transport shall support the full overhead framing structure 0 as specified in 8.4. The support of full overhead framing structure 1 and reduced overhead framing structures 2 and 3 is optional. + +Preservation of T-R interface byte boundaries (if present) at the U-R interface may be supported for any of the U-R interface framing structures. + +An ATU-R configured for STM transport may support reconstruction of a Network Timing Reference (NTR). + +## 8.2 ATM Transport Protocol Specific functionalities + +### 8.2.1 ATU-R input and output T interfaces for ATM transport + +The ATU-R input and output T interfaces are identical to the ATU-C input and output interfaces, as described in 7.2 and as shown in Figure 8-2. + +![Diagram of ATU-R functional interfaces to the ATM layer at the T-R reference point.](0f6e3cdce0f01d6ccceabcced508bb5b_img.jpg) + +The diagram illustrates the functional interfaces between the ATM layer and the ATU-R at the T-R reference point. On the left, the 'Customer Installation' contains the 'ATM layer'. Within the ATM layer, there are two sets of interfaces: 'P O R T 0' and 'P O R T 1'. 'PORT 0' is connected to an 'ATM0' block, which has four lines: 'Tx\_ATM0', 'Tx\_Cell\_Handshake0', 'Rx\_ATM0', and 'Rx\_Cell\_Handshake0'. 'PORT 1' is connected to an 'ATM1' block, which also has four lines: 'Tx\_ATM1', 'Tx\_Cell\_Handshake1', 'Rx\_ATM1', and 'Rx\_Cell\_Handshake1'. Both 'ATM0' and 'ATM1' blocks are connected to the 'ATU-R' on the right. A dashed line labeled 'T-R' separates the Customer Installation from the ATU-R. Below the ATM blocks, an 'NTR' (Network Timing Reference) line is shown, originating from the ATU-R and pointing back into the Customer Installation. A small 'X' symbol is shown within the Customer Installation, connected to the ATM layer. The diagram is labeled 'T1532560-99' at the bottom right. + +Diagram of ATU-R functional interfaces to the ATM layer at the T-R reference point. + +Figure 8-2/G.992.1 – ATU-R functional interfaces to the ATM layer at the T-R reference point + +### 8.2.2 ATM Cell specific functionalities + +The ATM cell specific functionalities performed at the ATU-R shall be identical to the ATM cell specific functionalities performed at the ATU-C, as described in 7.2.3. + +### 8.2.3 Framing Structure for ATM transport + +An ATU-R configured for ATM transport shall support the full overhead framing structures 0 and 1 as specified in 8.4. The support of reduced overhead framing structures 2 and 3 is optional. + +The ATU-R transmitter shall preserve T-R interface byte boundaries (explicitly present or implied by ATM cell boundaries) at the U-R interface, independent of the U-R interface framing structure. + +An ATU-R configured for ATM transport may support reconstruction of a Network Timing Reference (NTR). + +To ensure framing structure 0 interoperability between an ATM ATU-R and an ATM cell TC plus an STM ATU-C (i.e. ATM over STM), the following shall apply: + +- an STM ATU-C transporting ATM cells and not preserving V-C byte boundaries at the U-C interface shall indicate during initialization that frame structure 0 is the highest frame + +structure supported; + +- an STM ATU-C transporting ATM cells and preserving V-C byte boundaries at the U-C interface shall indicate during initialization that frame structure 0, 1, 2 or 3 is the highest frame structure supported, as applicable to the implementation; +- an ATM ATU-R receiver operating in framing structure 0 cannot assume that the ATU-C transmitter will preserve V-C interface byte boundaries at the U-C interface and shall therefore perform the cell delineation bit-by-bit (see 7.2.3.5). + +### 8.3 Network timing reference + +If the ATU-C has indicated that it will use indicator bits 20 to 23 (see 10.6.4) to transmit the change of phase offset, the ATU-R may deliver the 8 kHz signal to the T-R interface. + +### 8.4 Framing + +Framing of the upstream signal (ATU-R transmitter) closely follows the downstream framing (ATU-C transmitter), which is specified in 7.4, but with the following exceptions: + +- there are no ASx channels and no AEX byte; +- a maximum of three channels exist, so that only three $B_F$ , $B_I$ pairs are specified; +- the minimum RS FEC coding parameters and interleave depth differ (see Table 8-3); +- four bits of the fast and sync bytes are unused (corresponding to the bit positions used by the ATU-C transmitter to specify synchronization control for the ASx channels) (see Tables 8-1 and 8-2); +- the four indicator bits for NTR transport are not used in upstream direction. + +Two types of framing are defined: full overhead and reduced overhead. Furthermore, two versions of full overhead and two versions of reduced overhead are defined. The four resulting framing structures are defined as for the ATU-C in 7.4 and are referred to as framing structures 0, 1, 2 and 3. + +Requirements for framing structures to be supported depend upon the ATU-R being configured for either STM or ATM transport, and are defined in 8.1.4 and 8.2.3, respectively. + +As specified in clause 5, outside the ASx/LSx serial interfaces data bytes are transmitted MSB first in accordance with Recommendations G.703, G.707, I.361 and I.432.1. All serial processing in the ADSL frame (e.g. CRC, scrambling, etc.) shall, however, be performed LSB first, with the outside world MSB considered by the ADSL as LSB. As a result, the first incoming bit (outside world MSB) will be the first processed bit inside the ADSL (ADSL LSB). + +#### 8.4.1 Data symbols + +The ATU-R transmitter is functionally similar to the ATU-C transmitter, as specified in 7.4.1, except that up to three duplex data channels are synchronized to the 4 kHz ADSL DMT symbol rate (instead of up to four simplex and three duplex channels as is the case for the ATU-C) and multiplexed into the two separate buffers (fast and interleaved). The ATU-R transmitter and its associated reference points for data framing are shown in Figures 5-3 and 5-4. + +##### 8.4.1.1 Superframe structure + +The superframe structure of the ATU-R transmitter is identical to that of the ATU-C transmitter, as specified in 7.4.1.1 and shown in Figure 7-5. + +The ATU-R shall support the indicator bits defined in Table 7-2. The indicator bits, ib20-23, shall not transport NTR in the upstream direction and shall be set to "1". + +### 8.4.1.2 Frame structure (with full overhead) + +Each data frame shall be encoded into a DMT symbol, as described in 8.8 through 8.11.4. As specified for the ATU-C and shown in Figure 7-5, each frame is composed of a fast data buffer and an interleaved data buffer, and the frame structure has a different appearance at each of the reference points (A, B and C). The bytes of the fast data buffer shall be clocked into the constellation encoder first, followed by the bytes of the interleaved data buffer. Bytes are clocked least significant bit first. + +The assignment of bearer channels to the fast and interleaved buffers shall be configured during initialization (see 10.7.4) with the exchange of a $(B_F, B_I)$ pair for each data stream, where $B_F$ designates the number of bytes of a given data stream to allocate to the fast buffer, and $B_I$ designates the number of bytes allocated to the interleaved data buffer. + +The three possible $(B_F, B_I)$ pairs are $B_F(LSx)$ , $B_I(LSx)$ for $X = 0, 1$ and $2$ , for the duplex channels; they are specified as for the ATU-C in 10.7.4. + +#### 8.4.1.2.1 Fast data buffer + +The frame structure of the fast data buffer is shown in Figure 8-3 for the three reference points that are defined in Figures 5-3 and 5-4. This structure is the same as that specified for the ATU-C with the following exceptions: + +- ASx bytes do not appear; +- the AEX byte does not appear. + +![Diagram of Figure 8-3: Fast data buffer – ATU-R transmitter. The diagram shows three levels of data frame representation. The top level is labeled 'N_F bytes' and 'FEC output (point B) or constellation encoder input (point C) data frame'. The middle level is labeled 'K_F bytes' and 'Mux data frame (point A)'. The bottom level shows the byte breakdown of the Mux data frame: 'Fast byte' (1 byte), 'LS0' (C_F (LS0) bytes), 'LS1' (B_F (LS1) bytes), 'LS2' (B_F (LS2) bytes), 'LEX' (L_F bytes), and 'FEC bytes' (R_F bytes). Vertical dashed lines show the alignment between the levels.](f06d7a2fad72d80fe12fca1b65fc805b_img.jpg) + +Diagram of Figure 8-3: Fast data buffer – ATU-R transmitter. The diagram shows three levels of data frame representation. The top level is labeled 'N\_F bytes' and 'FEC output (point B) or constellation encoder input (point C) data frame'. The middle level is labeled 'K\_F bytes' and 'Mux data frame (point A)'. The bottom level shows the byte breakdown of the Mux data frame: 'Fast byte' (1 byte), 'LS0' (C\_F (LS0) bytes), 'LS1' (B\_F (LS1) bytes), 'LS2' (B\_F (LS2) bytes), 'LEX' (L\_F bytes), and 'FEC bytes' (R\_F bytes). Vertical dashed lines show the alignment between the levels. + +**Figure 8-3/G.992.1 – Fast data buffer – ATU-R transmitter** + +The following shall hold for the parameters shown in Figure 8-3: + +$$C_F(LS0) = 0 \quad \text{if } B_F(LS0) = 255 \text{ (11111111}_2\text{)} \quad (8-1)$$ + +$$= B_F(LS0) \quad \text{otherwise}$$ + +$$L_F = 0 \quad \text{if } B_F(LS0) = B_F(LS1) = B_F(LS2) = 0 \quad (8-2)$$ + +$$= 1 \quad \text{otherwise}$$ + +$$K_F = 1 + C_F(LS0) + B_F(LS1) + B_F(LS2) + L_F \quad (8-3)$$ + +$$N_F = K_F + R_F \quad (8-4)$$ + +where: + +$R_F$ = number of upstream FEC redundancy bytes in fast path. + +At reference point A (the mux data frame) in Figures 5-3 and 5-4, the fast buffer always contains at least the fast byte. This is followed by $B_F(LS0)$ bytes of channel LS0, then $B_F(LS1)$ bytes of channel LS1, and $B_F(LS2)$ bytes of channel LS2, and if any $B_F(LSx)$ is non-zero, a LEX byte. + +When $B_F(LS0) = 255 \text{ (11111111}_2\text{)}$ , no separate bytes are included for the LS0 channel. Instead, the 16 kbit/s C-channel shall be transported in every other LEX byte on average, using the synchronization byte to denote when to add the LEX byte to the LS0 bearer channel. + +$R_F$ FEC redundancy bytes shall be added to the mux data frame (reference point A) to produce the FEC output data frame (reference point B), where $R_F$ is given in the C-RATES1 signal options received from the ATU-C during initialization (see 10.6.2). Because the data from the fast data buffer is not interleaved, the constellation encoder input data frame (reference point C) is identical to the FEC output data frame (reference point B). + +#### 8.4.1.2.2 Interleaved data buffer + +The frame structure of the interleaved data buffer is shown in Figure 8-4 for the three reference points that are defined in Figures 5-3 and 5-4. This structure is the same as that specified for the ATU-C, with the following exceptions: + +- ASx bytes do not appear; +- the AEX byte does not appear. + +![Figure 8-4/G.992.1 – Interleaved data buffer – ATU-R transmitter. The diagram illustrates the data flow and buffering process. At the top, a 'Mux data frame (point A)' of K_I bytes is shown with fields: Sync byte (1 byte), LS0 (C_I bytes), LS1 (B_I bytes), LS2 (B_I bytes), and LEX (L_I bytes). Below this, a sequence of 'Mux data frame #0', 'Mux data frame #1', ..., 'Mux data frame #S-1' is shown, each K_I bytes long, followed by 'FEC bytes' of R_usi bytes. These are then shown as 'FEC output data frame #C', 'FEC output data frame #1', ..., 'FEC output data frame #S', each N_I bytes long. The diagram uses double-headed arrows to indicate byte ranges and fields.](29043c6ca27a7cfbc757a5d2eb029d33_img.jpg) + +Figure 8-4/G.992.1 – Interleaved data buffer – ATU-R transmitter. The diagram illustrates the data flow and buffering process. At the top, a 'Mux data frame (point A)' of K\_I bytes is shown with fields: Sync byte (1 byte), LS0 (C\_I bytes), LS1 (B\_I bytes), LS2 (B\_I bytes), and LEX (L\_I bytes). Below this, a sequence of 'Mux data frame #0', 'Mux data frame #1', ..., 'Mux data frame #S-1' is shown, each K\_I bytes long, followed by 'FEC bytes' of R\_usi bytes. These are then shown as 'FEC output data frame #C', 'FEC output data frame #1', ..., 'FEC output data frame #S', each N\_I bytes long. The diagram uses double-headed arrows to indicate byte ranges and fields. + +**Figure 8-4/G.992.1 – Interleaved data buffer – ATU-R transmitter** + +The following shall hold for the parameters shown in Figure 8-4: + +$$C_I(LS0) = 0 \quad \text{if } B_I(LS0) = 255 \text{ (11111111}_2\text{)} \quad (8-5)$$ + +$$= B_I(LS0) \quad \text{otherwise}$$ + +$$L_I = 0 \quad \text{if } B_I(LS0) = B_I(LS1) = B_I(LS2) = 0 \quad (8-6)$$ + +$$= 1 \quad \text{otherwise}$$ + +$$K_I = 1 + C_I(LS0) + B_I(LS1) + B_I(LS2) + L_I \quad (8-7)$$ + +$$N_I = (S \times K_I + R_I)/S \quad (8-8)$$ + +where: + +$R_I$ = number of upstream FEC redundancy bytes in interleaved path; and + +$S$ = number of mux data frames per FEC codeword (see 8.6). + +#### 8.4.1.3 Hyperframe structure (Annex C only) + +For Annex C, see C.5.1.2. + +#### 8.4.1.4 Subframe structure (Annex C only) + +For Annex C, see C.5.1.3. + +#### 8.4.1.5 Cyclic redundancy check (CRC) + +Two cyclic redundancy checks (CRCs) – one for the fast data buffer and one for the interleaved data buffer – are generated for each superframe and transmitted in the first frame of the following superframe. Eight bits per buffer type (fast or interleaved) per superframe are allocated to the CRC check bits. These bits are computed from the $k$ message bits using the equation: + +The CRC bits are transported in the fast byte (8 bits) of frame 0 in the fast data buffer, and the sync byte (8 bits) of frame 0 in the interleaved data buffer. + +The bits covered by the CRC include: + +- for the fast data buffer: + - *frame 0*: LSx bytes ( $X = 0, 1, 2$ ), followed by the LEX byte; + - *all other frames*: fast byte, followed by LSx bytes ( $X = 0, 1, 2$ ), and LEX byte. +- for the interleaved data buffer: + - *frame 0*: LSx bytes ( $X = 0, 1, 2$ ), followed by the LEX byte; + - *all other frames*: sync byte, followed by LSx bytes ( $X = 0, 1, 2$ ), and LEX byte. + +Each byte shall be clocked into the CRC least significant bit first. + +The CRC-generating polynomial, and the method of generating the CRC byte are the same as for the downstream data; these are specified in 7.4.1.3. + +#### 8.4.2 Synchronization + +If the bit timing base of the input user data streams is not synchronous with the ADSL modem timing base, the input data streams shall be synchronized to the ADSL timing base using the synchronization control mechanism (consisting of synchronization control byte and the LEX byte). Forward-error-correction coding shall always be applied to the synchronization control byte(s). + +If the bit timing base of the input user data streams is synchronous with the ADSL modem timing base, then the synchronization control mechanism is not needed. The synchronization control byte shall always indicate "no synchronization action" (see Table 8-1). + +##### 8.4.2.1 Synchronization for the fast data buffer + +Synchronization control for the fast data buffer can occur in frames 2 through 33 and 36 through 67 of an ADSL superframe as described in 7.4.1.1, where the fast byte may be used as the synchronization control byte. No synchronization action is to be taken for those frames in which the fast byte is used for CRC, fixed indicator bits, or EOC. + +The format of the fast byte when used as synchronization control for the fast data buffer shall be as given in Table 8-1. + +In the case where no signals are allocated to the interleaved data buffer, the sync byte carries the AOC data directly as shown in Figure 7-7. + +**Table 8-1/G.992.1 – Fast byte format for synchronization** + +| Bit | Application | Specific usage | +|----------|--------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------| +| sc7-sc4 | Not used | Set to "0 2 " until specified otherwise | +| sc3, sc2 | LSx channel designator | "00 2 ": channel LS0
"01 2 ": channel LS1
"10 2 ": channel LS2
"11 2 ": no synchronization action | +| sc1 | Synchronization control for the designated LSx channel | "1 2 ": add LEX byte to designated LSx channel
"0 2 ": delete last byte from designated LSx channel | +| sc0 | Synchronization/EOC designator | "0 2 ": perform synchronization control as indicated in sc7-sc1
"1 2 ": this byte is part of an EOC frame | + +If the bit timing base of the input bearer channels (LSx) is synchronous with the ADSL modem timing base, then ADSL systems need not perform synchronization control by adding or deleting LEX bytes to/from the designated LSx channels, and the synchronization control byte shall indicate "no synchronization action" (i.e. sc7-0 coded "000011X02", with X discretionary). + +When the data rate of the C-channel is 16 kbit/s, the LS0 bearer channel shall be transported in the LEX byte, using the "add LEX byte to designated LSx channel", with LS0 as the designated channel, every other frame on average. + +#### 8.4.2.2 Synchronization for the interleaved data buffer + +Synchronization control for the interleaved data buffer can occur in frames 1 through 67 of an ADSL superframe as described in 7.4.1.1, where the sync byte may be used as the synchronization control byte. No synchronization action shall be taken during frame 0, where the sync byte is used for CRC, and frames when the LEX byte carries the AOC. + +The format of the sync byte when used as synchronization control for the interleaved data buffer shall be as given in Table 8-2. In the case where no signals are allocated to the interleaved data buffer, the sync byte shall carry the AOC data directly, as shown in Figure 7-7 in 7.4.1.1. + +**Table 8-2/G.992.1 – Sync byte format for synchronization** + +| Bit | Application | Specific usage | +|----------|--------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| sc7-sc4 | Not used | Set to "0 2 " until specified otherwise | +| sc3, sc2 | LSx channel designator | "00 2 ":channel LS0
"01 2 ":channel LS1
"10 2 ":channel LS2
"11 2 ":no synchronization action | +| sc1 | Synchronization control for the designated LSx channel | "1 2 ": add LEX byte to designated LSx channel
"0 2 ": delete last byte from designated LSx channel | +| sc0 | Synchronization/AOC designator | "0 2 ": perform synchronization control as indicated in sc3-sc1
"1 2 ": LEX byte carries ADSL overhead control channel data; a delete synchronization control may be allowed as indicated in sc3-sc1 | + +When the data rate of the C-channel is 16 kbit/s, the LS0 bearer channel shall be transported in the LEX byte, using the "add LEX byte to designated LSx channel", with LS0 as the designated channel, every other frame on average. + +If the bit timing base of the input bearer channels (LSx) is synchronous with the ADSL modem timing base, then ADSL systems need not perform synchronization control by adding or deleting LEX bytes to/from the designated LSx channels, and the synchronization control byte shall indicate "no synchronization action". In this case, and when framing structure 1 is used, the sc7-0 shall always be coded "000011XX2", with X discretionary. When sc0 is set to "1", the LEX byte shall carry AOC. When sc0 is set to "0", the LEX byte shall be coded 0016. The sc0 may be set to "0" only in between transmissions of 5 concatenated and identical AOC messages. + +#### 8.4.3 Reduced overhead framing + +The format described in 8.4.1.2 for full overhead framing includes overhead to allow for the synchronization of three LSx bearer channels. When the synchronization function described in 8.4.2 is not required, the ADSL equipment may operate in a reduced overhead mode. This mode retains all the full overhead mode functions except synchronization control. When using the reduced overhead framing, the framing structure shall be as defined in 7.4.3.1 (when using separate fast and sync bytes) or 7.4.3.2 (when using merged fast and sync bytes). + +### 8.5 Scramblers + +The data streams output from the fast and interleaved buffers shall be scrambled separately using the same algorithm as for the downstream signal, specified in 7.5. + +### 8.6 Forward error correction + +The upstream data shall be Reed-Solomon coded and interleaved using the same algorithm as for the downstream data, specified in 7.6. + +The FEC coding overhead, the number of symbols per FEC codeword, and the interleave depth are given in the C-RATES1 options received from the ATU-C during initialization (see 10.6.2). + +The ATU-R shall support upstream transmission with at least any combination of the FEC coding capabilities shown in Table 8-3. + +**Table 8-3/G.992.1 – Minimum FEC coding capabilities for ATU-R** + +| Parameter | Fast buffer | Interleaved buffer | +|------------------------------------------------------------------------------------------|---------------------------------------------------|----------------------------------------------------------| +| Parity bytes per RS codeword | $R_F = 0, 2, 4, 6, 8, 10, 12, 14, 16$
(Note 1) | $R_I = 0, 2, 4, 6, 8, 10, 12, 14, 16$
(Notes 1 and 2) | +| DMT symbols per RS codeword | $S = 1$ | $S = 1, 2, 4, 8, 16$ | +| Interleave depth | not applicable | $D = 1, 2, 4, 8$ | +| NOTE 1 – $R_F$ can be $> 0$ only if $K_F > 0$ and $R_I$ can be $> 0$ only if $K_I > 0$ . | | | +| NOTE 2 – $R_I$ shall be an integer multiple of $S$ . | | | + +The ATU-R shall also support downstream transmission with at least any combination of the FEC coding capabilities shown in Table 7-7. + +### 8.7 Tone ordering + +The tone-ordering algorithm shall be the same as for the downstream data, specified in 7.7. + +## 8.8 Constellation encoder – Trellis version + +Block processing of Wei's 16-state 4-dimensional trellis code to improve system performance is optional. An algorithmic constellation encoder shall be used to construct constellations with a maximum number of bits equal to $N_{\text{upmax}}$ , where $8 \leq N_{\text{upmax}} \leq 15$ . + +The encoding algorithm shall be the same as that used for downstream data (with the substitution of the constellation limit of $N_{\text{upmax}}$ for $N_{\text{downmax}}$ ), specified in 7.8. + +## 8.9 Constellation encoder – Uncoded version + +An algorithmic constellation encoder shall be used to construct constellations with a maximum number of bits equal to $N_{\text{upmax}}$ , where $8 \leq N_{\text{upmax}} \leq 15$ . The encoding algorithm is the same as that used for downstream data (with the substitution of the constellation limit of $N_{\text{upmax}}$ for $N_{\text{downmax}}$ ), which is specified in 7.9. The constellation encoder shall not use trellis coding with this option. + +## 8.10 Gain scaling + +For the transmission of data symbols gain scaling, $g_i$ , shall be applied as requested by the ATU-C (see 10.8.13 and A.2.4.1 or B.2.2.1) and possibly updated during Showtime via the bit swap procedure. Only values of $g_i$ equal to 0 or within a range of approximately 0.19 to 1.33 (i.e. –14.5 dB to +2.5 dB) may be used. For the transmission of synchronization symbols, gain scaling shall be applied as defined in Annexes A, B and C. + +Each constellation point, $(X_i, Y_i)$ , i.e. complex number, $X_i + jY_i$ , output from the encoder is multiplied by $g_i$ : + +$$Z_i = g_i (X_i + jY_i) \quad (8-9)$$ + +NOTE – The $g_i$ define a scaling of the root mean square (rms) subcarrier levels relative to those used in R-MEDLEY (see 10.7.8). They are independent of any methods that manufacturers may use to simplify implementation (e.g. constellation nesting). + +## 8.11 Modulation + +The frequency spacing, $\Delta f$ , between subcarriers shall be 4.3125 kHz with a tolerance of $\pm 50$ ppm. + +### 8.11.1 Subcarriers + +#### 8.11.1.1 Data subcarriers + +The channel analysis signal, defined in 10.7, allows for a maximum of 31 carriers (at frequencies $n\Delta f$ ) to be used. The range of $n$ depends on the service option selected. For example, for ADSL above POTS (see Annex A) the lower limit is set by the POTS/ADSL splitting filters; the upper limit is set by the transmit and receive band-limiting filters, and shall be no greater than 31; the cut-off frequencies of these filters are at the discretion of the manufacturer because the range of usable $n$ is determined during the channel estimation. + +The data subcarriers for Annex B are defined in B.2.3. + +#### 8.11.1.2 Nyquist frequency + +The subcarrier at the Nyquist frequency shall not be used for user data and shall be real valued; other possible uses are for further study. + +The Nyquist frequency for Annexes A and C is specified in A.2.5. + +The Nyquist frequency for Annex B is specified in B.2.5. + +### 8.11.1.3 DC + +The subcarrier at DC (#0) shall not be used, and shall contain no energy. + +### 8.11.2 Modulation by the inverse discrete Fourier transform + +For Annexes A and C, see A.2.1. + +For Annex B, see B.2.6. + +### 8.11.3 Synchronization symbol + +The synchronization symbol permits recovery of the frame boundary after micro-interruptions that might otherwise force retraining. + +The data symbol rate, $f_{symb} = 4$ kHz, the subcarrier separation, $\Delta f = 4.3125$ kHz, and the IDFT size, $N = 64$ , are such that a cyclic prefix of 5 samples could be used. That is, + +$$(64 + 5) \times 4.0 = 64 \times 4.3125 = 276 \quad (8-10)$$ + +The cyclic prefix shall, however, be shortened to 4 samples, and a synchronization symbol (with a nominal length of 68 samples) inserted after every 68 data symbols. That is, + +$$(64 + 4) \times 69 = (64 + 5) \times 68 \quad (8-11)$$ + +The data pattern used in the synchronization symbol shall be as defined in the appropriate annexes. + +For Annexes A and C, see A.2.2. + +For Annex B, see B.2.7. + +The minimum set of subcarriers to be used is the set used for data transmission (i.e. those for which $b_i > 0$ ); subcarriers for which $b_i = 0$ may be used at a reduced PSD as defined in transmit PSD paragraphs of Annexes A, B and C. The data modulated onto each subcarrier shall be as defined above; it shall not depend on which subcarriers are used. + +### 8.11.4 Inverse synchronization symbol (Annex C only) + +For Annex C, see C.5.5.1. + +## 8.12 Cyclic prefix + +For Annexes A and C, see A.2.3. + +For Annex B, see B.2.8. + +## 8.13 Transmitter dynamic range + +The transmitter includes all analogue transmitter functions: the D/A converter, the anti-aliasing filter, the hybrid circuitry, and the POTS splitter. The transmitted signal shall conform to the frequency requirements described in 8.11.1 for frequency spacing. + +### 8.13.1 Maximum clipping rate + +The maximum output signal of the transmitter shall be such that the signal shall be clipped no more than 0.00001% of the time. + +### 8.13.2 Noise/distortion floor + +The signal-to-noise plus distortion ratio of the transmitted signal in a given subcarrier is specified as the ratio of the rms value of the full-amplitude tone in that subcarrier to the rms sum of all the non-tone signals in the 4.3125 kHz frequency band centred on the subcarrier frequency. This ratio is measured for each subcarrier used for transmission using a MultiTone Power Ratio (MTPR) test as + +shown in Figure 7-21. + +Over the transmission frequency band, the MTPR of the transmitter in any subcarrier shall be no less than $(3N_{\text{upi}} + 20)$ dB, where $N_{\text{upi}}$ is defined as the size of the constellation (in bits) to be used on subcarrier $i$ . The transmitter MTPR shall be +38 dB (corresponding to an $N_{\text{upi}}$ of 6) for any subcarrier. + +NOTE – Signals transmitted during normal initialization and data transmission cannot be used for this test because the DMT symbols have a cyclic prefix appended, and the PSD of a non-repetitive signal does not have nulls at any subcarrier frequencies. A gated FFT-based analyser could be used, but this would measure both the non-linear distortion and the linear distortion introduced by the transmit filter. Therefore this test will require that the transmitter be programmed with special software, probably to be used during development only. The subject of an MTPR test that can be applied to a production modem is for further study. + +#### **8.14 ATU-R Upstream Transmitter spectral response** + +Spectral masks for the three service options are defined in Annexes A, B, and C: + +For Annex A, see A.2.4. + +For Annex B, see B.2.2. + +For Annex C, see C.5.6. + +NOTE – The band from 25 to 276 kHz that is referred to is the union of the bands used for ADSL above POTS and ADSL above ISDN. Limits defined within this band apply also to any narrower bands used. + +#### **8.15 Dual Bitmapping and Rate Conversion (Annex C only)** + +For Annex C, see C.5.2. + +#### **8.16 FEXT Bitmapping (Annex C only)** + +For Annex C, see C.5.3. + +### **9 EOC Operations and Maintenance** + +#### **9.1 Clear EOC** + +Support of autonomous data messages is mandatory. It provides the physical layer channel defined in 6.1/G.997.1. The channel is provided in both the upstream and the downstream direction by transmission of autonomous messages with EOC field settings as shown in 9.2.3.4. + +These autonomous data messages may be transmitted from either the ATU-C or the ATU-R and are transparent to the current state of the EOC state machine. That is, these autonomous messages transporting clear channel data can be inserted regardless of the current state of the EOC state machine. There is no requirement that these autonomous messages be inserted contiguously. That is other EOC messages may be inserted between any two autonomous messages. There is also no requirement for any specific rate of insertion of autonomous messages into the EOC. + +When an autonomous data message is received, the byte payload is placed in a buffer on the receiving ATU. Assembly into PDUs is defined in Recommendation G.997.1. + +The clear EOC does not support flow control. It is assumed that a higher level protocol implemented over this data path will support a flow control mechanism if required. Additionally, any system implementing a stack and application using the clear EOC (such as that defined in Recommendation G.997.1) should disable, at the higher layers, the further sending of autonomous data frames should a significant number of these higher layer messages be left without response from the receiver. + +## 9.2 Embedded operations channel (EOC) requirements + +An embedded operations channel for communication between the ATU-C and ATU-R shall be used for in-service and out-of-service maintenance and for the retrieval of ATU-R status information and ADSL performance monitoring parameters. + +### 9.2.1 EOC organization and protocol + +The ADSL EOC allows the ATU-C (acting as master of the link) to invoke commands and the ATU-R (acting as slave) to respond to the commands. The ATU-C determines the EOC rate of the ADSL link; therefore only one EOC message shall be inserted in the upstream direction (by the ATU-R) for each received EOC message. One exception to this is for the "dying gasp" message, which is the only autonomous message currently allowed from the ATU-R and is inserted as soon as appropriate bytes are available. + +This subclause defines only the content and meaning of the EOC messages; their insertion into the data frames is defined in 7.4.1 and 8.4.1. + +### 9.2.2 EOC message structure + +The 13 bits of an EOC message are partitioned among five fields, which are summarized in Table 9-1 and defined in the following subclauses. The EOC protocol states are defined in 9.2.5. + +**Table 9-1/G.992.1 – EOC message fields** + +| Field # | Bit(s) | Description | Notes | +|---------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------| +| 1 | 1, 2 | Address field | Can address 4 locations | +| 2 | 3 | Data (0) or opcode (1) field | Data used for read/write or when an autonomous data message is sent | +| 3 | 4 | Byte parity field
Odd (1) or even (0) | Byte order indication for multi-byte transmission | +| 4 | 5 | Autonomous message field:
ATU-C
  • set to "1" for ATU-C commands sent to ATU-R
  • set to "0" for autonomous transfers
ATU-R
  • set to "1" for response to ATU-C command
  • set to "0" for autonomous transfers
| Set to "0" by ATU-R to send dying gasp message or autonomous data transfers | +| 5 | 6-13 | Information field | One out of 58 opcodes or 8 bits of data | + +#### 9.2.2.1 Address field (# 1) + +The two bits of the address field can address up to four locations. Only two locations are presently defined: + +- 112: ATU-C address; +- 002: ATU-R address. + +102 and 012 are reserved for future use, and are presently invalid. + +The ATU-C shall address messages to the ATU-R by setting the ADDRESS field equal to the ATU-R address. When responding to a message from the ATU-C, the ATU-R shall keep the ADDRESS field equal to its own ATU-R address. Only when sending an autonomous message to + +the ATU-C shall the ATU-R set the ADDRESS field equal to the ATU-C address. + +#### **9.2.2.2 Data or opcode field (# 2)** + +A 0 (zero) in this field indicates that the information field of the current EOC message contains a data byte; a 1 that it contains an operation code for an ADSL EOC message. + +#### **9.2.2.3 Byte parity field (# 3)** + +For the first byte of data that is to be either read or written, this bit shall be set to "1" to indicate "odd" byte. For the next byte, it shall be set to "0" to indicate "even" byte and so on, alternately. This bit helps to speed up multi-byte reads and writes of data by eliminating the need for intermediate opcodes to indicate to the far-end that the previous byte was successfully received. + +The byte parity field shall always be set to "1" if the EOC message is an autonomous message or if the information field carries an opcode different from the Next Byte opcode. The byte parity field may be set to "0" otherwise. + +#### **9.2.2.4 Autonomous message field (# 4)** + +At the ATU-C a 1 in this field designates that the current EOC message is an EOC protocol command (master) message; a 0 designates that this is an autonomous transfer that does not disrupt the current EOC protocol state at either the ATU-C or ATU-R. At the ATU-R a 1 in this field designates that the current EOC message is an EOC protocol response (slave) message; a 0 designates that it is an autonomous transfer that does not disturb the current EOC protocol state at either the ATU-C or the ATU-R. The only autonomous transfer currently defined for the ATU-C is the autonomous data transfer defined in 9.2.3.4. The ATU-R supports the "dying gasp" (see 9.2.5.4) message and upstream autonomous data transfers (defined in 9.2.3.4). + +#### **9.2.2.5 Information field (# 5)** + +Up to 58 different opcodes or 8 bits of (binary or ASCII) data may be encoded in the information field. + +The opcode set is restricted to codes that provide a minimum Hamming distance of 2 between all opcodes, and a minimum distance of 3 between certain critical codes and all other codes. + +### **9.2.3 EOC message sets** + +The ATU-C sends EOC (command) messages to the ATU-R to perform certain functions. Some of these functions require the ATU-R to activate changes in the circuitry (e.g. to send CRC bits that are corrupted). Other functions that can be invoked are to read from and write into data registers located at the ATU-R. The data registers are used for reading status- or performance-monitoring parameters from the ATU-R, or for limited maintenance extensions to the CI wiring distribution network or service modules. + +Some of these commands are "latching", meaning that a subsequent command shall be required to release the ATU-R from that state. Thus, multiple ADSL EOC-initiated actions can be in effect simultaneously. A separate command, "Return To Normal", is used to unlatch all latched states. This command is also used to bring the ADSL system to a known state, the idle state, when no commands are active in the ATU-R location. To maintain the latched state, the command "Hold State" shall be sent to bring the ADSL system to a known state, the Idle State. + +The ATU-C always issues the EOC messages, and the ATU-R acknowledges that it has received a message correctly by echoing it, or by sending a response message. + +There are four types of EOC messages: + +- bidirectional EOC messages: these are sent by the ATU-C, must be echoed by the ATU-R as an indication of correct reception and require an opcode; + +- ATU-C to ATU-R (downstream) messages: these are sent by the ATU-C, are not echoed by the ATU-R and require an opcode; +- ATU-R to ATU-C (upstream) messages: these are sent by the ATU-R, are not echoed by the ATU-C and require an opcode; these are EOC protocol responses to downstream commands or an autonomous message such as "dying gasp"(i.e. unsolicited); +- Autonomous Data Transfers: these are autonomous data transfers sent by either the ATU-C or ATU-R, they are unsolicited, are not echoed or acknowledged at the EOC layer, do not use an opcode and do not affect the EOC protocol state. + +All the EOC messages and their opcodes are summarized in Table 9-2. + +**Table 9-2/G.992.1 – EOC message opcodes** + +| HEX
(Note 1) | Opcode meaning | Direction
(Note 2) | Abbreviation
and notes | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------|-----------------------|---------------------------| +| 01 16 | Hold state | d/u | HOLD | +| F0 16 | Return all active conditions to normal | d/u | RTN | +| 02 16 | Perform "self test" | d/u | SLFTST | +| 04 16 | Unable to comply (UTC) | u | UTC | +| 07 16 | Request corrupt CRC | d/u | REQCOR (latching) | +| 08 16 | Request end of corrupt CRC | d/u | REQEND | +| 0B 16 | Notify corrupt CRC | d/u | NOTCOR (latching) | +| 0D 16 | Notify end of corrupt CRC | d/u | NOTEND | +| 0E 16 | End of data | d/u | EOD | +| 10 16 | Next byte | d | NEXT | +| 13 16 | Request update of test parameters | d/u | REQTPU | +| 20 16 , 23 16 , 25 16 , 26 16 ,
29 16 , 2A 16 , 2C 16 , 2F 16 ,
31 16 , 32 16 , 34 16 , 37 16 ,
38 16 , 3B 16 , 3D 16 , 3E 16 | Write data register numbers 0-F | d/u | WRITE | +| 40 16 , 43 16 , 45 16 , 46 16 ,
49 16 , 4A 16 , 4C 16 , 4F 16 ,
51 16 , 52 16 , 54 16 , 57 16 ,
58 16 , 5B 16 , 5D 16 , 5E 16 | Read data register numbers 0-F | d/u | READ | +| 19 16 , 1A 16 , 1C 16 , 1F 16 | Vendor proprietary protocols | d/u | | +| E7 16 | Dying gasp | u | DGASP | + +**Table 9-2/G.992.1 – EOC message opcodes (concluded)** + +| HEX
(Note 1) | Opcode meaning | Direction
(Note 2) | Abbreviation
and notes | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|-----------------------|-------------------------------------------------------------------------------| +| 15 16 , 16 16 , 80 16 , 83 16 ,
85 16 , 86 16 , 89 16 , 8A 16 ,
8C 16 , 8F 16 | Undefined codes | | These codes are reserved for future use and shall not be used for any purpose | +|

NOTE 1 – The opcode values are given in HEX (MSB left, LSB right) with the MSB mapping to bit eoc13 and the LSB to bit eoc6 (see Table 9-1). The values guarantee a minimum Hamming distance of:

  • • 2 between all opcodes (by requiring odd parity for all but two critical codes);
  • • 3 between the "Return to Normal" (or "idle") code and all other codes; and
  • • 3 between the "Dying Gasp" code and all other codes.

NOTE 2 – The three types of messages are identified as:

  • • d/u (downstream/upstream) bidirectional messages (9.2.3.1);
  • • d (downstream): ATU-C to ATU-R messages (9.2.3.2);
  • • u (upstream): ATU-R to ATU-C messages (9.2.3.3).
| | | | + +### 9.2.3.1 Bidirectional EOC messages + +Messages that may *be* sent by the ATU-C, and echoed by the ATU-R as an indication of correct reception are as follows (with their abbreviated names and hex opcodes in parentheses): + +- *Hold State*: (HOLD, 0116) This message tells the ATU-R to maintain the ATU-R EOC processor and any active ADSL EOC-controlled operations (such as latching commands) in their present state. +- *Return to Normal (Idle Code)*: (RTN, F016) This message releases all outstanding EOC-controlled operations (latched conditions) at the ATU-R and returns the ADSL EOC processor to its initial state. This code is also the message sent during idle states. +- *Request Corrupt CRC*: (REQCOR , 0716) This message requests the ATU-R to send corrupt CRCs to the ATU-C until cancelled by the "Request End of Corrupt CRC" or "Return to Normal" message. In order to allow multiple ADSL EOC-initiated actions to be in effect simultaneously, the "Request corrupt CRC" command shall be latching. +- *Request End of Corrupt CRC*: (REQEND, 0816) This message requests the ATU-R to stop sending corrupt CRCs toward the ATU-C. +- *Notify Corrupted CRC*: (NOTCOR, 0B16) This message notifies the ATU-R that intentionally corrupted CRCs will be sent from the ATU-C until cancellation is indicated by "Notify End of Corrupted CRC" or "Return to Normal". +- *Notify End of Corrupted CRC*: (NOTEND, 0D16) This message notifies the ATU-R that the ATU-C has stopped sending corrupted CRCs. +- *Perform Self Test*: (SLFTST, 0216) This message requests the ATU-R to perform a self test. The result of the self test shall be stored in a register at the ATU-R. After the ATU-R self test, the ATU-C reads the test results from the ATU-R register. +- *Receive/Write Data (Register #)*: (WRITE, see Table 9-2) This message directs the ATU-R to enter the Data Write Protocol state, receive data, and write it in the register specified by the Opcode. + +- *Read/Send Data (Register #)*: (READ, see Table 9-2) This message directs the ATU-R to enter the Data Read Protocol state, read data from the register specified by the Opcode, and transmit it to the ATU-C. +- *End of Data*: (EOD, 0E16) This message is sent by the ATU-C after it has sent all bytes of data to the ATU-R (see Note). +- *Request Test Parameter Update*: (REQTPU, 1316): This message requests the ATU-R to update the test parameter set as defined in 9.3.1.4 and 9.3.4.1. Test parameters shall be supported by the ATU-R and shall be updated within 10 seconds after the request is received. Updated test parameters may be read by the ATU-C thereafter. +- *Vendor Proprietary Opcodes*: (VPC, 1916, 1A16, 1C16, 1F16) Four opcodes have been reserved for vendor proprietary use. The ATU-C shall read the Vendor ID (identification) code register of the ATU-R to ensure compatibility between ATUs before using proprietary opcodes. +- *Undefined Command Codes*: All command codes not defined are reserved for future use, and shall not be used for any purpose. + +NOTE – This message has a slightly different meaning when sent by the ATU-R, as defined in 9.2.5.3.2. + +### 9.2.3.2 ATU-C to ATU-R messages + +One message that may be sent only by the ATU-C is: + +- *Next Byte*: (NEXT, 1016) This message is sent repeatedly by the ATU-C (toggling bit four for multi-byte data until all data has been sent) while it is in Data Read Protocol state (i.e. after the ATU-R has acknowledged the previously sent *Receive/Write Data* command). + +### 9.2.3.3 ATU-R to ATU-C messages + +Additional messages that may be sent only by the ATU-R are: + +- *Unable to Comply Acknowledgement*: (UTC, 0416) The ATU-R shall send this message when it receives an ADSL EOC message that it cannot perform, either because it does not recognize or implement the command or because the command is unexpected, given the current state of the ADSL EOC interface. An example of an unexpected command is one that indicates that the information field contains data, but that was not preceded by a "Write Data" command. +- *End of Data*: (EOD, 0E16) This message is sent by the ATU-R: + - in response to a "Next Byte" message from the ATU-C that is received after all bytes have been read from the currently addressed ATU-R register; or + - in response to a message from the ATU-C that contains a data byte after all bytes have been written to the currently addressed ATU-R register. +- *Dying gasp*: (DGASP, E716) This is the only autonomous (i.e. unsolicited) message that the ATU-R may send; see 9.2.5.4. +- *Vendor Proprietary Opcodes*: (VPC, 1916, 1A16, 1C16, 1F16) Four opcodes have been reserved for vendor proprietary use. + +### 9.2.3.4 Autonomous Data Transfers + +Autonomous Data Transfers are unsolicited data transfers that can be initiated by either the ATU-C or ATU-R. Unlike normal EOC protocol messages, autonomous data transfers require no echoing (acknowledgements) at the EOC layer nor repetition. This light weight approach to data transfers enables high speed, unsolicited management exchanges ( $32 \times 8 \times 4/68 = 15$ kbit/s) between the ATU-C and ATU-R without impacting the current EOC protocol states. + +Autonomous Data Transfers can be inserted regardless of the state of the EOC state machine. An Autonomous Data Transfer will not change the EOC message/echo-response protocol state nor can it count as a response to any ATU-C protocol message. An Autonomous Data Transfer allows for the transport of a single byte of data and does not require the repetitive EOC message/echo-response protocol. Consecutive Autonomous Data Transfers can be issued as soon as "fast" byte pairs are available for EOC messages. The flow of Autonomous Data Transfers can be interrupted at any time for bidirectional, ATU-C to ATU-R or ATU-R to ATU-C EOC messages. The ATU-C shall format all Autonomous Data Transfers (to the ATU-R) with the Address field (#1) set to 002 (ATU-R's address); the Data field (#2) set to 0 (data); the Byte parity field (#3) set to 1; the Autonomous message field (#4) shall be set to 0 (autonomous); and the information field (#5) will be used for 8 bits of data. The ATU-R shall format all Autonomous Data Transfers (to the ATU-C) with the Address field (#1) set to 112 (ATU-C's address); the Data field (#2) set to 0 (data); the Byte parity field (#3) set to 1; the Autonomous message field (#4) shall be set to 0 (autonomous); and the information field (#5) will be used for 8 bits of data. + +#### 9.2.4 Data registers in the ATU-R + +The ATU-R registers shall be defined as: + +- ATU-R Vendor ID: 8 bytes (see 9.3.3/G.994.1); +- ATU-R Revision Number: vendor discretionary; +- ATU-R Serial number (32 bytes): The format of the ATU-R Serial Number is vendor discretionary; +- Self Test Results: The most significant byte of the Self Test Results shall be 0016 if the self test passed, and 0116 if it failed (the meaning of "failure" is vendor discretionary); other values are reserved for future use. The length and syntax of the remainder are vendor discretionary; +- Line attenuation (1 byte): The line attenuation is defined in 9.5.1; +- SNR Margin (1 byte): The SNR margin is defined in 9.5.1; +- ATU-R configuration (30 bytes): The ATU-R configuration data, as defined in 8.4 and Table 10-9, shall be read (one byte for each variable) in the following order: + - downstream $B_F(AS0), B_I(AS0), B_F(AS1), B_I(AS1), B_F(AS2), B_I(AS2), B_F(AS3), B_I(AS3)$ ; + - downstream $B_F(LS0), B_I(LS0), B_F(LS1), B_I(LS1), B_F(LS2), B_I(LS2)$ , reserved; + - upstream $B_F(LS0), B_I(LS0), B_F(LS1), B_I(LS1), B_F(LS2), B_I(LS2)$ , reserved; + - downstream $RS_F, RS_I, S, D$ ( $RS_F = R_F, RS_I = R_I/S$ ); + - upstream $RS_F, RS_I, S, D$ ( $RS_F = R_F, RS_I = R_I/S$ ). + +Both reserved bytes shall be set to 0016. + +Table 9-3 summarizes the ATU-R data registers and their applications. + +**Table 9-3/G.992.1 – ATU-R data registers** + +| Reg. # | Use | Length | Description | +|----------------------------------|---------------------|--------------------------------|------------------------------------------| +| 0 16 | Read (R) | 8 bytes
(see 9.3.3/G.994.1) | ATU-R vendor ID | +| 1 16 | R | Vendor discretionary | ATU-R version number minus one | +| 2 16 | R | 32 bytes | ATU-R serial # | +| 3 16 | R | Vendor discretionary | Self test results | +| 4 16 | Read/Write
(R/W) | Vendor discretionary | Vendor discretionary | +| 5 16 | R/W | Vendor discretionary | Vendor discretionary | +| 6 16 | R | 1 byte | Line attenuation | +| 7 16 | R | 1 byte | SNR margin | +| 8 16 | R | 30 bytes | ATU-R Configuration (see 8.4 and Note 1) | +| 9 16 -F 16 | Reserved | Reserved | (Note 2) | + +NOTE 1 – Registers shall be read most significant byte first. +NOTE 2 – Registers 9 through F are reserved for future use; ATU-R shall respond UTC (unable to comply) if requested to read from or write to one of these registers. + +**9.2.5 EOC protocol states** + +The ADSL EOC protocol operates in a repetitive command and response mode. The ATU-C acts as the master and issues command messages; the ATU-R acts as slave and responds to the messages issued by the ATU-C. Three identical properly-addressed consecutive (i.e. no other EOC messages are received in between) messages shall be received before an action is initiated (both at ATU-C and ATU-R). Only one command and only three or fewer messages, under the control of the ATU-C, shall be outstanding (i.e. unacknowledged) at any one time. + +NOTE – This restriction on the number of messages guarantees that an ATU-R with fewer opportunities to insert EOC frames into the upstream path will be able to acknowledge all EOC messages from the ATU-C. + +The procedure for dealing with outstanding messages at the ATU-C is shown in Figure 9-1. Only when it has no outstanding messages may the ATU-C send a message different from the previous message sent; this will then result in one outstanding message. When one or two messages are outstanding, the ATU-C may only repeat the previous message sent; thereby ensuring that all outstanding messages will be identical. + +![ATU-C state diagram for outstanding EOC messages. The diagram shows four states: '3 outstanding messages', '2 outstanding messages', '1 outstanding message', and '0 outstanding messages (see Note)'. Transitions are labeled S (Send new message), R (Repeat last message), E (EOC message received), and DC (Dummy code). Transitions from 3 to 2, 2 to 1, and 1 to 0 are labeled E. Transitions from 2 to 3, 1 to 2, and 0 to 1 are labeled R. Transition from 0 to 3 is labeled S. A self-loop labeled DC is shown above the '3 outstanding messages' state.](e8f5117fb031f413a836525061addd61_img.jpg) + +``` + +stateDiagram-v2 + [*] --> 0_outstanding: S + 0_outstanding --> 1_outstanding: R + 1_outstanding --> 2_outstanding: R + 2_outstanding --> 3_outstanding: R + 3_outstanding --> 2_outstanding: E + 2_outstanding --> 1_outstanding: E + 1_outstanding --> 0_outstanding: E + 3_outstanding --> 3_outstanding: DC + + state "3 outstanding messages" as 3_outstanding + state "2 outstanding messages" as 2_outstanding + state "1 outstanding message" as 1_outstanding + state "0 outstanding messages (see Note)" as 0_outstanding + +``` + +T1532590-99 + +ATU-C state diagram for outstanding EOC messages. The diagram shows four states: '3 outstanding messages', '2 outstanding messages', '1 outstanding message', and '0 outstanding messages (see Note)'. Transitions are labeled S (Send new message), R (Repeat last message), E (EOC message received), and DC (Dummy code). Transitions from 3 to 2, 2 to 1, and 1 to 0 are labeled E. Transitions from 2 to 3, 1 to 2, and 0 to 1 are labeled R. Transition from 0 to 3 is labeled S. A self-loop labeled DC is shown above the '3 outstanding messages' state. + +S = Send new message + R = Repeat last message + E = EOC message received + DC = Dummy code + +NOTE – Immediately after initialization, the ATU-C shall have no outstanding messages. + +**Figure 9-1/G.992.1 – ATU-C state diagram for outstanding EOC messages** + +For E, R and S all the EOC messages with bit 5 set to "1" shall be considered. Other EOC messages shall not cause a change of state in the EOC state machine. + +Whenever there are three outstanding messages, the ATU-C shall stop sending messages and stuff the available EOC bandwidth with dummy synchronization control bytes (see 7.4.1.1). Sending messages may be resumed after receiving one or more acknowledgements (echoes) from the ATU-R. Only one command shall be outstanding at any time. Therefore, all outstanding messages shall be identical. To deal with messages that are not echoed by the ATU-R (e.g. those that are erased from the line due to impulse noise and will therefore remain outstanding), the ATU-C shall implement an adequate error recovery mechanism. This mechanism does not affect interoperability and is therefore outside the scope of this Recommendation. + +The EOC protocol state diagrams of the ATU-R and ATU-C shall be as shown in Figures 9-2 and 9-3, respectively. + +![State machine diagram for EOC receiver at ATU-R. States include Data Read State (odd), Data Read State (even), Pre-read state, Idle state, UTC state, Pre-write state, Data Write State (odd), and Data Write State (even). Transitions are triggered by messages like #NEXT odd, #NEXT even, #READ, #WRITE, #DATA odd, #DATA even, #any message, #RTN, #HOLD, #EOD, and #not supported message. Logic includes index management (i, i++) and data handling (read, write, echo, return).](ec96d99a16edb981eb7defe41a79b57f_img.jpg) + +``` + +stateDiagram-v2 + [*] --> Idle state + Idle state --> Data Read State (odd): #READ == 3 + Idle state --> Data Read State (even): #READ == 3 + Idle state --> UTC state: #any message == 1 + Idle state --> Pre-read state: #RTN == 3 or #HOLD == 3 + Idle state --> Pre-write state: #WRITE == 3 + Idle state --> Data Write State (odd): #DATA odd == 3 + Idle state --> Data Write State (even): #DATA even == 3 + Idle state --> UTC state: #any message == 3 + Data Read State (odd) --> Data Read State (even): #NEXT even == 3 + Data Read State (even) --> Data Read State (odd): #NEXT odd == 3 + Data Read State (odd) --> Pre-read state: #NEXT odd == 3 + Data Read State (even) --> Pre-read state: #NEXT even == 3 + Data Read State (odd) --> Data Read State (odd): i++ + Data Read State (even) --> Data Read State (even): i++ + Data Read State (odd) --> Idle state: #EOD == 3 + Data Read State (even) --> Idle state: #EOD == 3 + Pre-read state --> Data Read State (odd): #NEXT odd == 3 + Pre-read state --> Data Read State (even): #NEXT even == 3 + Pre-read state --> Idle state: #READ == 3 + Pre-read state --> Data Write State (odd): #DATA odd == 3 + Pre-read state --> Data Write State (even): #DATA even == 3 + Pre-read state --> UTC state: #any message == 3 + Pre-read state --> Idle state: #RTN == 3 or #HOLD == 3 + Pre-read state --> Data Read State (odd): #NEXT odd == 3 + Pre-read state --> Data Read State (even): #NEXT even == 3 + Pre-read state --> Idle state: #EOD == 3 + Pre-write state --> Data Read State (odd): #NEXT odd == 3 + Pre-write state --> Data Read State (even): #NEXT even == 3 + Pre-write state --> Idle state: #READ == 3 + Pre-write state --> Data Write State (odd): #DATA odd == 3 + Pre-write state --> Data Write State (even): #DATA even == 3 + Pre-write state --> UTC state: #any message == 3 + Pre-write state --> Idle state: #RTN == 3 or #HOLD == 3 + Pre-write state --> Data Read State (odd): #NEXT odd == 3 + Pre-write state --> Data Read State (even): #NEXT even == 3 + Pre-write state --> Idle state: #EOD == 3 + Data Write State (odd) --> Data Write State (even): #DATA even == 3 + Data Write State (even) --> Data Write State (odd): #DATA odd == 3 + Data Write State (odd) --> Data Write State (odd): i++ + Data Write State (even) --> Data Write State (even): i++ + Data Write State (odd) --> Idle state: #EOD == 3 + Data Write State (even) --> Idle state: #EOD == 3 + Data Write State (odd) --> UTC state: #any message == 3 + Data Write State (even) --> UTC state: #any message == 3 + Data Write State (odd) --> Pre-read state: #NEXT odd == 3 + Data Write State (even) --> Pre-read state: #NEXT even == 3 + Data Write State (odd) --> Data Read State (odd): #NEXT odd == 3 + Data Write State (even) --> Data Read State (even): #NEXT even == 3 + Data Write State (odd) --> Data Read State (odd): #DATA odd == 3 + Data Write State (even) --> Data Read State (even): #DATA even == 3 + UTC state --> Idle state: #any message == 1 + UTC state --> UTC state: #not supported message == 3 from any state + +``` + +State machine diagram for EOC receiver at ATU-R. States include Data Read State (odd), Data Read State (even), Pre-read state, Idle state, UTC state, Pre-write state, Data Write State (odd), and Data Write State (even). Transitions are triggered by messages like #NEXT odd, #NEXT even, #READ, #WRITE, #DATA odd, #DATA even, #any message, #RTN, #HOLD, #EOD, and #not supported message. Logic includes index management (i, i++) and data handling (read, write, echo, return). + +T1532600-99 + +Figure 9-2/G.992.1 – EOC receiver state machine at ATU-R + +![State machine diagram for EOC receiver at ATU-C. States include Data Read State (odd), Data Read State (even), Pre-read state, Idle state, UTC state, Pre-write state, Data Write State (odd), and Data Write State (even). Transitions are labeled with conditions like #'DATA odd](d1ad05f1189b0d80188fee24ae33c112_img.jpg) + +``` + +stateDiagram-v2 + [*] --> Idle state + Idle state --> Pre-read state: #'READ"==3 + Pre-read state --> Idle state + Pre-read state --> Data Read State (odd): #'DATA odd"==3 + Data Read State (odd) --> Data Read State (even): #'DATA even"==3 + Data Read State (even) --> Data Read State (odd): #'DATA odd"==3 + Data Read State (odd) --> Pre-read state: (#"RTN"==3) || (#"HOLD"==3) + Data Read State (even) --> Pre-read state: (#"RTN"==3) || (#"HOLD"==3) + Idle state --> Pre-write state: #'WRITE"==3 + Pre-write state --> Idle state + Pre-write state --> Data Write State (odd): #'DATA odd"==3 + Data Write State (odd) --> Data Write State (even): #'DATA even"==3 + Data Write State (even) --> Data Write State (odd): #'DATA odd"==3 + Data Write State (odd) --> Pre-write state: #'EOD"==3 + Data Write State (even) --> Pre-write state: #'EOD"==3 + Idle state --> UTC state: #'any message"==1 + UTC state --> Idle state: #'UTC"==3 + UTC state --> [*]: from any state + +``` + +**Data Read State (odd)** + +``` + +if (#"DATA odd"≥3) +{ if (i≤LENGTH) +return("DATA odd",d[i]) +} + +``` + +**Data Read State (even)** + +``` + +if (#"DATA even"≥3) +{ if (i≤LENGTH) +return("DATA even",d[i]) +} + +``` + +**Pre-read state** + +``` + +i=1; + +``` + +**Pre-write state** + +``` + +i=1; + +``` + +**Transitions:** + +- Idle state to Pre-read state: #'READ"==3 +- Pre-read state to Data Read State (odd): #'DATA odd"==3 +- Data Read State (odd) to Data Read State (even): #'DATA even"==3 +- Data Read State (even) to Data Read State (odd): #'DATA odd"==3 +- Data Read State (odd) to Pre-read state: (#"RTN"==3) || (#"HOLD"==3) +- Data Read State (even) to Pre-read state: (#"RTN"==3) || (#"HOLD"==3) +- Idle state to Pre-write state: #'WRITE"==3 +- Pre-write state to Data Write State (odd): #'DATA odd"==3 +- Data Write State (odd) to Data Write State (even): #'DATA even"==3 +- Data Write State (even) to Data Write State (odd): #'DATA odd"==3 +- Data Write State (odd) to Pre-write state: #'EOD"==3 +- Data Write State (even) to Pre-write state: #'EOD"==3 +- Idle state to UTC state: #'any message"==1 +- UTC state to Idle state: #'UTC"==3 +- UTC state to [\*]: from any state + +State machine diagram for EOC receiver at ATU-C. States include Data Read State (odd), Data Read State (even), Pre-read state, Idle state, UTC state, Pre-write state, Data Write State (odd), and Data Write State (even). Transitions are labeled with conditions like #'DATA odd + +T1532610-99 + +Figure 9-3/G.992.1 – EOC receiver state machine at ATU-C + +The following shall govern state changes as shown in Figures 9-2 and 9-3: + +- 1) The protocol state changes are performed based on received messages. At ATU-C, received messages are responses from the ATU-R to messages sent from the ATU-C. Depending on the ATU-C receiver protocol state, the ATU-C transmitter message set may be restricted. It is left up to the ATU-C transmitter to organize and send a sequence of messages such that the right response from the ATU-R is achieved based on the receiver protocol state machines. +- 2) *(#"message"==N)* is true if and only if the previously received N messages are identical (i.e. all 13 bits equal) and properly addressed (i.e. having ATU-R address). *(#"message"==1)* means the most recently received message is different (in at least 1 out of 13 bits) from the immediately preceding message and is properly addressed. +- 3) Moving to another state (based on the message received) shall be considered first, then the (same or new) state shall be executed. At the ATU-R execution of commands in the Idle state shall be as described in 9.2.5.3 (invoking latching, unlatching or self test). +- 4) All the EOC messages with bit 5 set to "1" shall be considered as received messages and cause an EOC response message at the ATU-R. Other EOC messages shall not cause a change of state in the EOC state machine and shall not cause an EOC response message at the ATU-R. + +The responses allowed from the ATU-R fall into three categories: + +- message/echo-response protocol states: Idle State and EXE State; +- message/unable-to-Comply-response protocol state: UTC State; +- message/data-response protocol states: Data Read States and Data Write States (Data Read States includes Pre-Read, Data Read odd and Data Read even states) (Data Write State includes Pre-Write, Data Write odd and Data Write even states). + +In addition to these states, one autonomous message shall be allowed from the ATU-R to the ATU-C to indicate "dying gasp". This message does not change the protocol state, nor does it count as a response to any ATU-C message; however, other actions (e.g. an automatic reset at the ATU-C) taken as a result of receiving this message may lead to a change of state (e.g. back to Idle State). + +The EOC protocol shall enter the Message/Echo-response protocol state (Idle state) when the ATUs transition from the initialization and training sequence to steady state transmission. In order to cause the desired action in the ATU-R, the ATU-C shall repeat the message (without exceeding the limit of outstanding messages) until it receives three identical consecutive EOC message echoes from the ATU-R. This completes the command and response protocol, but the ATU-C may continue to send the same message thereafter. The command and response protocol for that message must be completed before a new message (containing a new command), which may induce a different protocol state in the ATU-R, may be issued. + +At the ATU-R, depending on the state it is in, various restricted sets of EOC messages shall be acceptable. These sets shall be as shown in Table 9-4. Reception of other, inapplicable, messages shall result in an Unable-to-Comply (UTC) response to the ATU-C. + +**Table 9-4/G.992.1 – EOC messages acceptable at the ATU-R** + +| ATU-R state | EOC messages acceptable at the ATU-R | | | | +|----------------------|--------------------------------------|-----------|-----|------| +| Idle | all messages acceptable | | | | +| UTC | all messages acceptable | | | | +| Data pre-read | Read | NEXT odd | RTN | HOLD | +| Data read odd, even | NEXT odd | NEXT even | RTN | HOLD | +| Data pre-write | WRITE | DATA odd | EOD | | +| Data write odd, even | DATA odd | DATA even | EOD | | + +**9.2.5.1 Message/echo-response protocol state** + +This state is identical to the Idle state shown in Figures 9-2 and 9-3. + +To initiate an action at the ATU-R, the ATU-C shall begin sending EOC messages with the Data/opcode set to "1" and with the appropriate message opcode in the information field. + +The ATU-R shall initiate action when, and only when, three identical, consecutive, and properly addressed EOC frames that contain a message recognized by the ATU-R have been received. The ATU-R shall respond to all received messages. The response shall be an echo of the received ADSL EOC message. The combination of the ATU-C sending an ADSL EOC frame and the ATU-R echoing the frame back comprises the message/echo-response protocol state. + +For the ATU-C to confirm correct reception of the message by the ATU-R, the message/echo-response ADSL EOC protocol state is repeated until the master node receives three identical and consecutive echoes. This serves as an implicit acknowledgement to the ATU-C that the ATU-R has correctly received the transmitted message and is acting on it. This completes the message/echo-response protocol mode. + +Because EOC frames are inserted into ADSL frames only when the appropriate byte is available, the amount of time it takes to complete a message under error-free conditions will depend on the vendor's synchronization control algorithm, on the number of signals allocated to the fast buffer, and on the rates of those signals. + +The ATU-C continuously sends the activating message after the receipt of the three valid echoes, or alternatively, it may switch to sending the "Hold State" message. If the message was one of the latching commands, then the ATU-R shall maintain the commanded condition until the ATU-C issues the appropriate command that ends the specific latched condition or until the ATU-C issues the "Return to Normal" command (at which time all latched conditions in the ATU-R must be terminated). + +**9.2.5.2 Message/unable-to-comply response protocol state** + +When the ATU-R does not support a message that it has received three times identically and consecutively, it shall respond with the Unable-To-Comply (UTC) ADSL EOC response message with its own address in lieu of a third identical and consecutive echo. In this manner, the ATU-R will switch to the message/UTC-response protocol state. + +The transmission by the ATU-R and reception by the ATU-C of three identical, consecutive, properly-addressed Unable-To-Comply messages constitutes notification to the ATU-C that the ATU-R does not support the requested function, at which time the ATU-C may abandon its attempt. + +**9.2.5.3 Message/data-response protocol state** + +The ATU-C may either write data into, or read data from the ATU-R memory. + +### 9.2.5.3.1 Data read protocol + +To read data from the ATU-R, the ATU-C shall send an appropriate read opcode message to the ATU-R that specifies the register to be read. After receiving at least three identical and consecutive acknowledgements, the ATU-C shall request the first byte to be sent from the ATU-R by sending "Next Byte" messages with bit four set to "1", indicating a request for an "odd" byte. The ATU-R shall respond to these "Next Byte" messages by echoing them until it has received three such messages consecutively, identically and properly addressed. Beginning with the third such reception, the ATU-R shall respond by sending the first byte of the register in the information field of an ADSL EOC frame with bit four set to "1" to indicate "odd byte" and with bit 3 set to "0" to indicate that the EOC frame is a data frame (as opposed to a frame that contains an opcode in the information field). The ATU-C continues to send the "Next Byte" message with bit four set to "odd byte", and the ATU-R continues to respond with a data frame containing the first byte of data and bit four equal to "odd byte", until the ATU-C has received at least three consecutive, identical and properly addressed data frames with bit four set to "odd byte". + +If there are more data to be read, the ATU-C shall request the second byte of data by sending "Next Byte" messages with bit four set to "0" ("even byte"). The ATU-R echoes all messages received until three such "Next Byte" messages have been received, and on the third consecutive, identical and properly addressed "Next Byte" message, the ATU-R starts sending data frames containing the second byte of the register with bit four set to "even byte". The ATU-C continues to send the "Next Byte" message with bit four set to "even byte", and the ATU-R continues to respond with a data frame containing the second byte of data and bit four set to "even byte". + +The process continues for the third and all subsequent bytes with the value of bit four toggling from "odd byte" to "even byte" or vice versa, on each succeeding byte. Each time bit four is toggled, the ATU-R echoes for two correct frames, and starts sending the data frame on the third reception. The process ends only when all data in the register has been read. + +To continue reading data, once the ATU-R is in the Data Read odd or even State, the only message that the ATU-C is allowed to send is the "Next Byte" message with bit four toggling. To end the data read mode abnormally, the ATU-C sends either "Hold State" or "Return to Normal", depending on whether any latched states are to be retained. If the ATU-R receives any other message three times consecutively, identically and properly addressed while it is in Data Read odd or even State, it shall go into the UTC State. + +If, after all bytes have been read from the ATU-R register, the ATU-C continues to send the "Next Byte" message with bit four toggled, then the ATU-R shall send an "End of Data" message (with bit three set to "1" indicating opcode) beginning with the third such reception. + +For the ATU-C, the data read mode ends either when the ATU-C has received the last requested data byte three times consecutively, identically and properly addressed, or when the ATU-C has received three consecutive, identical and properly addressed "End of Data" messages with bit three set to "1". The ATU-C shall then switch itself and the ATU-R over to the Idle State with the "Hold State" or "Return to Normal" message, and the ATU-R shall release the register and leaves the Data Read State after receiving three identical, consecutive and properly addressed "Hold State" or "Return to Normal" messages. + +### 9.2.5.3.2 Data write protocol + +To write data to the ATU-R's memory, the ATU-C shall send a "Write Data" opcode message to the ATU-R that specifies the register to be written. When the ATU-R acknowledges with three consecutive, identical and properly addressed echo messages, the ATU-C sends the first byte of data. The ATU-R shall acknowledge the receipt of the byte with an echo of the message. After the ATU-C is satisfied with three identical, consecutive and properly addressed echo responses, it shall start sending the next byte of data. Each time the ATU-C receives at least three identical and consecutive correct data echo responses, it shall switch to sending the next byte of data. It shall also toggle the + +"odd/even" bit accordingly. ("Next Byte" messages are not used in the Data Write mode.) The ATU-C shall end the write mode with the "End of Data" message indicating to the ATU-R to release the register and return to the Idle State. + +To continue writing data, once the ATU-R is in the Data Write odd or even state, the only message that the ATU-C is allowed to send is the "DATA Byte" message with bit 3 set to "0" and with bit four toggling or, to end the Data Write state abnormally, the ATU-C may switch to the "EOD" message. If the ATU-R receives any other message three times consecutively, identically and properly addressed while it is in Data Write state, it shall go into the UTC state. + +If, after all bytes have been written to the ATU-R register, the ATU-C continues to send a next byte of data, then the ATU-R shall send an "End of Data" message (with bit three set to "1" indicating opcode), beginning with the third such reception. + +#### **9.2.5.4 "Dying gasp"** + +The ATU-R shall have the ability to detect when the electrical power has been shut off. After such detection of a near-end Loss-of-Power (LPR) condition (see 9.3.4.1), the ATU-R shall insert priority EOC messages into the ADSL upstream data to implement a "dying gasp" as an LPR indicator. The "dying gasp" EOC message shall have bit 5 set to "0" to indicate autonomous message, bit 3 set to "1" to indicate opcode, and shall contain the "dying gasp" opcode (see Table 9-2) in the information field. + +At least six contiguous dying gasp EOC messages shall be inserted in the next (at least twelve) available ADSL upstream bytes available for EOC (see 8.4.1) beginning with an even-numbered frame, regardless of the number of EOC frames received in the downstream channel. + +The ATU-C shall not send a response to a "dying gasp" message back to the ATU-R. An LPR indicator is present at the ATU-C if at least 4 "dying gasp" messages are received within the last twelve contiguous upstream bytes available for EOC, beginning with the an even-numbered frame (see Loss-of-Power primitive definition in 9.3.4). Sending the "dying gasp" shall not cause the ATU-R to change the EOC protocol state, nor shall receiving it cause the ATU-C to immediately change state. + +### **9.3 In-service performance monitoring and surveillance** + +ADSL systems have been designed to deliver packet/cell-based payloads. However, when ADSL systems operate in the STM mode non-cell based data paths may be transported. The performance monitoring capabilities required to maintain those data paths are embedded within the packet/cell systems. The ADSL system shall support the data path monitoring requirements as required by the specific payload technology (Figure 9-4). + +![Diagram of in-service surveillance of the ADSL link from the standpoint of ATU-C. The diagram shows the flow of data and control signals between Servers, Network, ATU-C, Loop plant, ATU-R, and Service Modules. The ATU-C is the central focus, with arrows indicating the flow of primitives and indicators. The legend at the bottom defines Downstream and Upstream signals.](7ec36a0a9788e1cb33df5372695498c8_img.jpg) + +The diagram illustrates the in-service surveillance of an ADSL link from the perspective of the ATU-C (Adaptive Transceiver Unit - Central Office). The components shown are Servers, Network, ATU-C, Loop plant, ATU-R (Adaptive Transceiver Unit - Remote), and Service Modules. The ATU-C and ATU-R are connected via the Loop plant. The ATU-C is connected to the Network, which is connected to the Servers. The ATU-R is connected to the Service Modules. The ATU-C and ATU-R are connected to the Service Modules via a Full-duplex link. The ATU-C and ATU-R are connected to the Service Modules via a Simplex link. The ATU-C and ATU-R are connected to the Loop plant via a Full-duplex link. The ATU-C and ATU-R are connected to the Loop plant via a Simplex link. The ATU-C and ATU-R are connected to the Loop plant via a Full-duplex link. The ATU-C and ATU-R are connected to the Loop plant via a Simplex link. + +1 Detect near-end primitives at ATU-R + +Services: Simplex + +Full-duplex + +Service Modules + +T1532620-99 + +ADSL Link + +Loop plant + +ATU-C + +ATU-R + +1 Detect near-end primitives at ATU-C + +4 Detect far-end primitives at ATU-C from indicators + +3 Report indicators (including loss of ATU-R AC power) + +2 Set indicators for reporting of primitives in overhead + +5 Support near-end and far-end monitoring at ATU-C + +ATU-C ↔ ATU-R + +Downstream → Composite ADSL Digital Signals each with overhead (and embedded operations channel – EOC) + +← Upstream + +Diagram of in-service surveillance of the ADSL link from the standpoint of ATU-C. The diagram shows the flow of data and control signals between Servers, Network, ATU-C, Loop plant, ATU-R, and Service Modules. The ATU-C is the central focus, with arrows indicating the flow of primitives and indicators. The legend at the bottom defines Downstream and Upstream signals. + +**Figure 9-4/G.992.1 – In-service surveillance of the ADSL link shown from standpoint of ATU-C** + +### 9.3.1 ADSL line related primitives + +#### 9.3.1.1 ADSL line related near-end anomalies + +Four near-end anomalies are defined: + +- **Forward error correction interleaved (FEC-I) anomaly:** An FEC-I anomaly occurs when a received FEC code for the interleaved data stream indicates that errors have been corrected. +- **Forward error correction fast (FEC-F) anomaly:** An FEC-F anomaly occurs when a received FEC code for the fast data stream indicates that errors have been corrected. +- **Cyclic redundancy check interleaved (CRC-I) anomaly:** A CRC-I anomaly occurs when a received CRC-8 code for the interleaved data stream is not identical to the corresponding locally generated code. +- **Cyclic redundancy check fast (CRC-F) anomaly:** A CRC-F anomaly occurs when a received CRC-8 code for the fast data stream is not identical to the corresponding locally generated code. + +#### 9.3.1.2 ADSL line related far-end anomalies + +Similarly, four far-end anomalies are defined: + +- **Far-end forward error correction interleaved (FFEC-I) anomaly:** An FFEC-I anomaly is an FEC-I anomaly detected at the far-end that is reported once per superframe by the FECC-I indicator. The FECC-I indicator shall be coded "1" to indicate that no FEC-I anomaly is present in the previous superframe and shall be coded to "0" to indicate that at least one FEC-I anomaly is present in the previous superframe. An FFEC-I anomaly occurs when a received FECC-I indicator is set to "0". An FFEC-I anomaly terminates when a received FECC-I indicator is set to "1". + +- **Far-end forward error correction fast (FFEC-F) anomaly:** An FFEC-F anomaly is an FEC-F anomaly detected at the far-end and is reported once per superframe by the FECC-F indicator. The FECC-F indicator shall be coded and reported in the same way as the FECC-I indicator. The FFEC-F anomaly shall occur and terminate in the same way as the FEBE-I anomaly. +- **Far-end Block Error interleaved (FEBE-I) anomaly:** An FEBE-I anomaly is a CRC-I anomaly detected at the far-end and is reported once per superframe by the FEBE-I indicator (see 7.4.1.1). The FEBE-I indicator shall be coded "1" to indicate that no CRC-I anomaly is present in the previous superframe and shall be coded "0" to indicate that a CRC-I anomaly is present in the previous superframe. An FEBE-I anomaly occurs when a received FEBE-I indicator is set to "0". An FEBE-I anomaly terminates when a received FEBE-I indicator is set to "1". +- **Far-end Block Error fast (FEBE-F) anomaly:** An FEBE-F anomaly is a CRC-F anomaly detected at the far-end and is reported once per superframe by the FEBE-F indicator (see 7.4.1.1). The FEBE-F indicator shall be coded and reported in the same way as the FEBE-I indicator. The FEBE-F anomaly shall occur and terminate in the same way as the FEBE-I anomaly. + +### 9.3.1.3 ADSL line related near-end defects + +Two near-end defects are defined: + +- **Loss-of-signal (LOS) defect:** A pilot tone reference power is established by averaging the ADSL pilot tone power for 0.1 s after the start of steady state data transmission (i.e. after initialization), and a threshold shall be set at 6 dB below this. A LOS defect then occurs when the level of the received ADSL pilot tone power, averaged over a 0.1 s. period, is lower than the threshold, and terminates when measured in the same way it is at or above the threshold. +- **Severely errored frame (SEF) defect:** An SEF defect occurs when the content of two consecutively received ADSL synchronization symbols does not correlate with the expected content over a subset of the tones. An SEF defect terminates when the content of two consecutively received ADSL synchronization symbols correlate with the expected contents over the same subset. The correlation method, the selected subset of tones, and the threshold for declaring these defect conditions are implementation discretionary. + +For Annex C, see C.6.1. + +### 9.3.1.4 ADSL line related far-end defects + +Similarly, two far-end defects are defined: + +- **Loss-of-signal (LOS) defect:** A reference power is established by averaging the ADSL power over a 0.1 s period and over a subset of tones after the start of steady state data transmission (i.e. after initialization), and a threshold shall be set at 6 dB below this. A LOS defect occurs when the level of the received ADSL power, averaged over a 0.1 s period and over the same subset of tones, is lower than the threshold, and terminates when measured in the same way it is at or above the threshold. The subset of tones, over which the ADSL power is averaged, is implementation discretionary and may be restricted at the ATU-R to only the downstream pilot tone. +- **Far-end Remote defect indication (RDI):** An RDI defect is an SEF defect detected at the far-end and is reported once per superframe by the RDI indicator. The RDI indicator (see 7.4.1.1) shall be coded "1" to indicate that no SEF defect is present in the previous superframe and shall be coded "0" to indicate that an SEF defect is present in the previous superframe. An RDI defect occurs when a received RDI indicator is set to "0". An RDI defect terminates when a received RDI indicator is set to "1". + +For Annex C, see C.6.1.2. + +### 9.3.2 STM data path related primitives + +In case STM data are transported on the U-interface, various ADSL payload types can be used. These payload types are not specified in this Recommendation and are for further study. The ADSL payload related primitives for STM transport are specific to a particular payload type and are for further study. + +### 9.3.3 ATM data path related primitives + +#### 9.3.3.1 ATM data path related near-end anomalies + +Six near-end anomalies are defined: + +- **No Cell Delineation interleaved (NCD-I) anomaly:** An NCD-I anomaly occurs immediately after ATM Cell TC start-up when ATM data are allocated to the interleaved buffer and as long as the cell delineation process operating on these data is in the HUNT or PRESYNC state (see Figure 7-3). Once cell delineation is acquired, subsequent losses of cell delineation shall be considered OCD-I anomalies. +- **No Cell Delineation fast (NCD-F) anomaly:** An NCD-F anomaly occurs immediately after ATM Cell TC start-up when ATM data are allocated to the fast buffer and as long as the cell delineation process operating on these data is in the HUNT or PRESYNC state (see Figure 7-3). Once cell delineation is acquired, subsequent losses of cell delineation shall be considered OCD-F anomalies. +- **Out of Cell Delineation interleaved (OCD-I) anomaly:** An OCD-I anomaly occurs when ATM data are allocated to the interleaved buffer and the cell delineation process operating on these data transitions from SYNC to HUNT state (see Figure 7-3). An OCD-I anomaly terminates when the cell delineation process transitions from PRESYNC to SYNC state or when the LCD-I defect maintenance state is entered. +- **Out of Cell Delineation fast (OCD-F) anomaly:** An OCD-F anomaly occurs when ATM data are allocated to the fast buffer and the cell delineation process operating on these data transitions from SYNC to HUNT state (see Figure 7-3). An OCD-F anomaly terminates when the cell delineation process transitions from PRESYNC to SYNC state or when the LCD-F defect maintenance state is entered. +- **Header Error Control interleaved (HEC-I) anomaly:** An HEC-I anomaly occurs when an ATM cell header error check fails on the interleaved data (see 7.2.3.6). +- **Header Error Control fast (HEC-F) anomaly:** An HEC-F anomaly occurs when an ATM cell header error check fails on the fast data (see 7.2.3.6). + +#### 9.3.3.2 ATM data path related far-end anomalies + +Similarly, six far-end anomalies are defined: + +- **Far-end No Cell Delineation interleaved (FNCD-I) anomaly:** An FNCD-I anomaly is an NCD-I anomaly detected at the far-end and is reported once per superframe by the NCD-I indicator (see 7.4.1.1). The NCD-I indicator shall be coded "1" to indicate no NCD-I anomaly or OCD-I anomaly or LCD-I defect is present in the previous superframe and shall be coded "0" to indicate that at least one NCD-I anomaly or OCD-I anomaly or LCD-I defect is present in the previous superframe. An FNCD-I anomaly occurs immediately after ATU start-up and terminates if a received NCD-I indicator is coded "1". +- **Far-end No Cell Delineation fast (FNCD-F) anomaly:** An FNCD-F anomaly is an NCD-F anomaly detected at the far-end and is reported once per superframe by the NCD-F indicator (see 7.4.1.1). The NCD-F indicator shall be coded and reported in the same way as the NCD-I indicator. The FNCD-F anomaly shall occur and terminate in the same way as the + +FNCD-I anomaly. + +- **Far-end Out of Cell Delineation interleaved (FOCD-I) anomaly:** An FOCD-I anomaly is an OCD-I anomaly detected at the far-end and is reported once per superframe by the NCD-I indicator (see 7.4.1.1). An FOCD-I anomaly occurs if no FNCD-I anomaly is present and a received NCD-I indicator is coded "0". An FOCD-I anomaly terminates if a received NCD-I indicator is coded "1". +- **Far-end Out of Cell Delineation fast (FOCD-F) anomaly:** An FOCD-F anomaly is an OCD-F anomaly detected at the far-end and is reported once per superframe by the NCD-F indicator (see 7.4.1.1). The FOCD-F anomaly shall occur and terminate in the same way as the FOCD-I anomaly. +- **Far-end Header Error Control interleaved (FHEC-I) anomaly:** An FHEC-I anomaly is an HEC-I anomaly detected at the far-end and is reported once per superframe by the HEC-I indicator (see 7.4.1.1). The HEC-I indicator shall be coded "1" to indicate that no HEC-I anomaly is present in the previous superframe and shall be coded "0" to indicate that at least one HEC-I anomaly is present in the previous superframe. An FHEC-I anomaly occurs when a received HEC-I indicator is set to "0". An FHEC-I anomaly terminates when a received HEC-I indicator is set to "1". +- **Far-end Header Error Control fast (FHEC-F) anomaly:** An FHEC-F anomaly is an HEC-F anomaly detected at the far-end and is reported once per superframe by the HEC-F indicator (see 7.4.1.1). The HEC-F indicator shall be coded and reported in the same way as the HEC-I indicator. The FHEC-F anomaly shall occur and terminate in the same way as the FHEC-I anomaly. + +NOTE – The HEC-I and HEC-F anomalies are reported once per superframe. This results in a low granularity of hec anomaly reporting since hundreds of ATM cells may be received over a one superframe time period. + +### 9.3.3.3 ATM data path related near-end defects + +Two near-end defects are defined: + +- **Loss of Cell Delineation interleaved (LCD-I) defect:** An LCD-I defect occurs when at least one OCD-I anomaly is present in each of 4 consecutive superframes and no SEF defect is present. An LCD-I defect terminates when no OCD-I anomaly is present in 4 consecutive superframes. +- **Loss of Cell Delineation fast (LCD-F) defect:** An LCD-F defect occurs when at least one OCD-F anomaly is present in each of 4 consecutive superframes and no SEF defect is present. An LCD-F defect terminates when no OCD-I anomaly is present in 4 consecutive superframes. + +### 9.3.3.4 ATM data path related far-end defects + +Similarly, two far-end defects are defined: + +- **Far-end Loss of Cell Delineation interleaved (FLCD-I) defect:** An FLCD-I defect is an LCD-I defect detected at the far-end and is reported by the NCD-I indicator (see 7.4.1.1). An FLCD-I defect occurs when an FOCD-I anomaly is present and 4 consecutively received NCD-I indicators are coded 0 and no RDI defect is present. An FLCD-I defect terminates if four consecutively received NCD-I indicators are coded "1". +- **Far-end Loss of Cell Delineation fast (FLCD-F) defect:** An FLCD-F defect is an LCD-F defect detected at the far-end and is reported by the NCD-F indicator (see 7.4.1.1). An FLCD-F defect occurs and terminates in the same way as the FLCD-I defect. + +### 9.3.4 Other ADSL indicators, parameters and signals + +#### 9.3.4.1 Other near-end primitives + +One other near-end primitive is defined: + +- **Loss-of-power (LPR):** An LPR primitive occurs when the ATU electrical supply (mains) power drops to a level equal to or below the manufacturer-determined minimum power level required to ensure proper operation of the ATU. An LPR primitive terminates when the power level exceeds the manufacturer determined minimum power level. + +#### 9.3.4.2 Other far-end primitives + +Similarly, one other far-end primitive is defined: + +- **Far-end Loss-of-power (LPR):** A far-end LPR primitive is an LPR primitive detected at the far-end and is reported by the LPR indicator. The LPR indicator shall be coded with emergency priority in the next six available outgoing EOC messages (see the EOC protocol for "dying gasp" in 9.2.5.4). A far-end LPR primitive occurs when an LPR indicator is present. A far-end LPR primitive terminates if for a period of 0.5 s no LPR indicator is present and no near-end LOS defect is present. The condition for an LPR indicator being present is defined in the EOC protocol for "dying gasp" (9.2.5.4). + +### 9.4 Failures and Performance Parameters + +Failures, performance parameters and storage and reporting thereof shall be implemented as defined in Recommendation G.997.1. + +### 9.5 Test Parameters + +The attenuation (ATN) and signal-to-noise ratio (SNR) margin test parameters apply to on-demand test requests; e.g. to check for adequate physical media performance margin at acceptance and after repair verification, or at any other time following the execution of initialization and training sequence of the ADSL system. ATN and SNR, as measured by the receivers at both the ATU-C and the ATU-R shall be externally accessible from the ATU-C, but they are not required to be continuously monitored. They are made available on-demand as defined in 9.2.3. + +#### 9.5.1 Near-end test parameters + +The following near-end test parameters shall be provided at the ATU-C and the ATU-R: + +- **Attenuation (ATN):** The attenuation is the difference in dB between the power received at the near-end and that transmitted from the far-end. Received signal power in dBm is the sum of all data-carrying (i.e. $b_i > 0$ ) DMT subcarrier powers averaged over a 1 second period. Transmitted signal power is $-3.65 - 2n + 10 \log (\sum g_i^2)$ dBm, summed over the data-carrying subcarriers. The attenuation ranges from 0 to 63.5 dB with 0.5 dB steps. +- **Signal-to-Noise Ratio (SNR) margin:** The signal-to-noise ratio margin represents the amount of increased received noise (in dB) relative to the noise power that the system is designed to tolerate and still meet the target BER of $10^{-7}$ , accounting for all coding (e.g. trellis coding, RS FEC) gains included in the design. The SNR margin ranges from -64.0 dB to +63.5 dB with 0.5 dB steps. + +For Annex C, see C.6.2.1. + +### 9.5.2 Far-end test parameters + +The following far-end test parameters shall be provided at the ATU-C: + +- **Far-end Attenuation (ATN):** The far-end attenuation is the attenuation measured at the far-end. It can be read from the EOC ATN register using the EOC command set (see 9.2.4). The EOC ATN register shall be coded as an unsigned integer, ranging from 0 to 127, corresponding to a 0 to 63.5 dB attenuation (0.5 dB steps). +- **Far-end Signal-to-Noise Ratio (SNR) margin:** The far-end signal-to-noise ratio margin is the signal-to-noise ratio margin measured at the far-end. It can be read from the EOC SNR register using the EOC command set (see 9.2.4). The EOC SNR register shall be coded as a 2's complement signed integer, ranging from -128 to +127, corresponding to a -64 to +63.5 dB signal-to-noise ratio margin (0.5 dB steps). + +For Annex C, see C.6.2.2. + +## 10 Initialization + +### 10.1 Overview + +#### 10.1.1 Basic functions of initialization + +ADSL transceiver initialization is required in order for a physically connected ATU-R and ATU-C pair to establish a communications link. The procedures for initiating a connection are specified in Recommendation G.994.1. This clause specifies the transceiver initialization and training procedures. + +In order to maximize the throughput and reliability of this link, ADSL transceivers shall determine certain relevant attributes of the connecting channel and establish transmission and processing characteristics suitable to that channel. The time line of Figure 10-1 provides an overview of this process. In Figure 10-1, each receiver can determine the relevant attributes of the channel through the transceiver training and channel analysis procedures. Certain processing and transmission characteristics can also be established at each receiver during this time. During the exchange process, each receiver shares with its corresponding far-end transmitter certain transmission settings that it expects to see. Specifically, each receiver communicates to its far-end transmitter the number of bits and relative power levels to be used on each DMT subcarrier, as well as any messages and final data rates information. For highest performance, these settings should be based on the results obtained through the transceiver training and channel analysis procedures. + +![Figure 10-1/G.992.1 – Overview of initialization. The diagram shows two horizontal timelines for ATU-C and ATU-R. ATU-C starts with Handshake Procedures (10.2 and G.994.1), followed by Transceiver training (10.4), Channel analysis (10.6), and Exchange (10.8). ATU-R starts with Handshake Procedures (10.3 and G.994.1), followed by Transceiver training (10.5), Channel analysis (10.7), and Exchange (10.9). A 'Time →' arrow indicates the sequence of events from left to right.](985267cff5b5d65ce5c180ff2ef37118_img.jpg) + +ATU-C + +| | | | | +|--------------------------------------------|--------------------------------|----------------------------|--------------------| +| Handshake Procedures
(10.2 and G.994.1) | Transceiver training
(10.4) | Channel analysis
(10.6) | Exchange
(10.8) | +|--------------------------------------------|--------------------------------|----------------------------|--------------------| + +ATU-R + +| | | | | +|--------------------------------------------|--------------------------------|----------------------------|--------------------| +| Handshake Procedures
(10.3 and G.994.1) | Transceiver training
(10.5) | Channel analysis
(10.7) | Exchange
(10.9) | +|--------------------------------------------|--------------------------------|----------------------------|--------------------| + +Time → + +Figure 10-1/G.992.1 – Overview of initialization. The diagram shows two horizontal timelines for ATU-C and ATU-R. ATU-C starts with Handshake Procedures (10.2 and G.994.1), followed by Transceiver training (10.4), Channel analysis (10.6), and Exchange (10.8). ATU-R starts with Handshake Procedures (10.3 and G.994.1), followed by Transceiver training (10.5), Channel analysis (10.7), and Exchange (10.9). A 'Time →' arrow indicates the sequence of events from left to right. + +**Figure 10-1/G.992.1 – Overview of initialization** + +Determination of channel attribute values and establishment of transmission characteristics requires that each transceiver produce, and appropriately respond to, a specific set of precisely-timed signals. This clause describes these initialization signals, along with the rules that determine the proper starting and ending time for each signal. This description is made through the definition of initialization signalling states in which each transceiver will reside, and the definition of + +initialization signals that each transceiver will generate. A state and the signal generated while in that state have the same name, which may sometimes, for clarity, be prefixed by "state" or "signal". + +The sequence of generated downstream and upstream states/signals for a successful initialization procedure is shown by the time lines of Figures 10-1 to 10-4; details of the timing of the states are shown in Figures 10-5 and 10-6. The dashed arrows indicate that the change of state in the ATU-x at the head of the arrow is caused by a successful reception of the last signal shown in the box at the base of the arrow. For example, in Figure 10-3, the ATU-R stays in state R-REVERB3 until it finishes receiving C-CRC2, at which point it moves on to R-SEGUE2 after an appropriate delay (see 10.7.2). + +NOTE – The figures show the sequence of events in a successful initialization. + +An overall state diagram is specified in Annex D, including the handling of failures to detect signals, timeouts, etc. + +The description of a signal will consist of three parts: + +- The first part is a description of the voltage waveform that the transmitter shall produce at its output when in the corresponding state. The output voltage waveform of a given initialization signal is described using the DMT transmitter reference models shown in Figures 5-1 to 5-4. +- The second is a statement of the required duration, expressed in DMT symbol periods, of the signal. This signal duration may be a constant or may depend upon the detected signalling state of the far-end transceiver. The duration of a single DMT symbol period depends on whether the cyclic prefix is being used; some initialization signals contain a cyclic prefix, and some do not. ATU-C signals up to and including C-SEGUE1 are transmitted without a cyclic prefix; those from C-RATES1 on are transmitted with a prefix. Similarly, ATU-R signals up to and including R-SEGUE1 do not use a prefix; those from R-REVERB3 onward do. The duration of any signal in seconds is therefore the defined number of DMT symbol periods times the duration of the DMT symbol being used. +- The third part of a signal's description is a statement of the rule specifying the next state. + +### **10.1.2 Transparency to methods of separating upstream and downstream signals** + +Manufacturers may choose to implement this Recommendation using either frequency-division-multiplexing (FDM) or echo cancelling (overlapped spectrum) to separate upstream and downstream signals. The initialization procedure described here ensures compatibility between these different implementations by specifying all upstream and downstream control signals to be in the appropriate, but narrower, frequency bands that would be used by an FDD transceiver, and by defining a time period during which an overlapped spectrum transceiver can train its echo canceller. + +### **10.1.3 Implementation of service options for ADSL** + +The initialization procedure described here uses single tones to identify specific options. The frequencies of these tones vary depending upon whether the ADSL service is offered with POTS or ISDN service as defined in Recommendation G.961, Appendix I, II, or III. + +These frequencies are therefore identified here only as variables, which are defined in Annexes A, B, and C of this Recommendation. + +### **10.1.4 Resetting during initialization and data transmission** + +Resetting may occur if errors or malfunctions are detected or timeout limits are exceeded at various points in the initialization sequence and SHOWTIME. An ATU executes a reset by transitioning to G.994.1 procedures. An ATU-R detecting an error condition shall transition to R-SILENT0 (see Recommendation G.994.1). An ATU-C detecting an error condition shall transition to C-SILENT1 (see Recommendation G.994.1). + +Annex D specifies the state transitions that shall occur if errors or malfunctions are detected or timeout limits are exceeded at various points in the initialization sequence. Annex D also specifies conditions for which retraining may be required during data transmission (i.e. after a successful initialization). + +### 10.1.5 Initialization with Hyperframe (Annex C only) + +For Annex C, see C.7.1. + +## 10.2 Handshake – ATU-C + +The detailed procedures for handshake at the ATU-C are defined in Recommendation G.994.1. An ATU-C, after power-up or on conditions shown in Figure D.1, shall enter the initial Recommendation G.994.1 state C-SILENT1. The ATU-C may transition to C-TONES under instruction of the network. From either state, operation shall proceed according to the procedures defined in Recommendation G.994.1. + +If G.994.1 procedures select this Recommendation as the mode of operation, the ATU-C shall transition to state C-QUIET2 at the conclusion of G.994.1 operation. All subsequent signals shall be transmitted using PSD levels as defined in the remainder of this subclause. + +### 10.2.1 CL messages + +An ATU-C wishing to indicate G.992.1 capabilities in a G.994.1 CL message shall do so by setting to ONE at least one of the Standard Information Field {SPar(1)} G.992.1 bits as defined in Table 23/G.994.1. For each G.992.1 {SPar(1)} bit set to ONE, a corresponding {NPar(2)} field shall also be present (see 9.4/G.994.1). The G.994.1 CL message {NPar(2)} fields corresponding to the {SPar(1)} bits are defined in Table 10-1. + +**Table 10-1/G.992.1 – ATU-C CL message NPar(2) bit definitions** + +| NPar(2) bit | Definition | +|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------| +| R-ACK1 | Shall always be set to ONE. Signifies that the ATU-C is capable of sending C-PILOT1A, C-QUIET3A, C-PILOT2 and C-QUIET5 during transceiver training. | +| R-ACK2 | Shall always be set to ONE in a CL message. Signifies that the ATU-C is capable of sending C-PILOT1, C-PILOT2 and C-PILOT3 during transceiver training. | +| Tones 1 to 32 | See B.3.1.1. | +| STM | If set to ONE, signifies that the ATU-C can be configured for STM bit sync transport. | +| ATM | If set to ONE, signifies that the ATU-C can be configured for ATM cell transport. | +| EOC-Clear | If set to ONE, signifies that the ATU-C supports transmission and reception of G.997.1 OAM frames. | +| DBM | See C.7.2.1. | + +At least one of the STM and ATM bits shall be set to ONE in a CL message. + +### 10.2.2 MS messages + +An ATU-C selecting a G.992.1 mode of operation in a G.994.1 MS message shall do so by setting to ONE the appropriate Standard Information Field {SPar(1)} G.992.1 bits as defined in Table 23/G.994.1. For the G.992.1 {SPar(1)} bit set to ONE, a corresponding {NPar(2)} field shall also be present (see 9.4/G.994.1). The G.994.1 MS message {NPar(2)} fields corresponding to the {SPar(1)} bit are defined in Table 10-2. + +**Table 10-2/G.992.1 – ATU-C MS message NPar(2) bit definitions** + +| NPar(2) bit | Definition | +|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| R-ACK1 | Signifies that the ATU-C shall send C-PILOT1A, C-QUIET3A, C-PILOT2 and C-QUIET5 during transceiver training. | +| R-ACK2 | Signifies that the ATU-C shall send C-PILOT1, C-PILOT2 and C-PILOT3 during transceiver training. | +| Tones 1 to 32 | See B.3.1.2. | +| STM | Signifies that the ATU-C is configured for STM bit sync transport. | +| ATM | Signifies that the ATU-C is configured for ATM cell transport. | +| EOC-Clear | Set to ONE, if and only this bit was set to ONE in both last previous CL message and last previous CLR message. Signifies that both ATU-C and ATU-R may transmit and receive G.997.1 OAM frames. | +| DBM | See C.7.2.2. | + +One and only one of the R-ACK1 and R-ACK2 bits shall be set to ONE in an MS message sent from the ATU-C. If both bits are enabled in the CL and CLR message, the R-ACK1 or R-ACK2 selection is at the ATU-C's discretion. + +One and only one of the STM and ATM bits shall be set to ONE in an MS message sent from the ATU-C. If both bits are enabled in the CL and CLR message, the STM or ATM selection is at the ATU-C's discretion. + +### **10.3 Handshake – ATU-R** + +The detailed procedures for handshake at the ATU-R are defined in Recommendation G.994.1. An ATU-R, after power-up or on conditions shown in Figure D.2, shall enter the initial G.994.1 state R-SILENT0. Upon command from the host controller, the ATU-R shall initiate handshaking by transitioning from the R-SILENT0 state to the G.994.1 R-TONES-REQ state. Operation shall then proceed according to the procedures defined in Recommendation G.994.1. + +If G.994.1 procedures select this Recommendation as the mode of operation, the ATU-R shall transition to state R-QUIET2 at the conclusion of G.994.1 operation. All subsequent signals shall be transmitted using PSD levels as defined in the remainder of this subclause. + +#### **10.3.1 CLR messages** + +An ATU-R wishing to indicate G.992.1 capabilities in a G.994.1 CLR message shall do so by setting to ONE at least one of the Standard Information Field {SPar(1)} G.992.1 bits as defined in Table 23/G.994.1. For each G.992.1 {SPar(1)} bit set to ONE, a corresponding {NPar(2)} field shall also be present (see 9.4/G.994.1). The G.994.1 CLR message {NPar(2)} fields corresponding to the {SPar(1)} bits are defined in Table 10-3. + +**Table 10-3/G.992.1 – ATU-R CLR message NPar(2) bit definitions** + +| NPar(2) bit | Definition | +|--------------------|------------------------------------------------------------------------------------------------------------------------------------------| +| R-ACK1 | If set to ONE, signifies that the ATU-R is capable of receiving C-PILOT1A, C-QUIET3A, C-PILOT2 and C-QUIET5 during transceiver training. | +| R-ACK2 | If set to ONE, signifies that the ATU-R is capable of receiving C-PILOT1, C-PILOT2 and C-PILOT3 during transceiver training. | +| Tones 1 to 32 | See B.3.2.1. | +| STM | If set to ONE, signifies that the ATU-R can be configured for STM bit sync transport. | +| ATM | If set to ONE, signifies that the ATU-R can be configured for ATM cell transport. | +| EOC-Clear | If set to ONE, signifies that the ATU-R supports transmission and reception of G.997.1 OAM frames. | +| DBM | See C.7.3.1. | + +At least one of the R-ACK1 and R-ACK2 bits shall be set to ONE in a CLR message. + +At least one of the STM and ATM bits shall be set to ONE in a CLR message. + +### 10.3.2 MS messages + +An ATU-R selecting a G.992.1 mode of operation in a G.994.1 MS message shall do so by setting to ONE the appropriate Standard Information Field {SPar(1)} G.992.1 bits as defined in Table 23/G.994.1. For the G.992.1 {SPar(1)} bit set to ONE, a corresponding {NPar(2)} field shall also be present (see 9.4/G.994.1). The G.994.1 MS message {NPar(2)} fields corresponding to the {SPar(1)} bit are defined in Table 10-4. + +**Table 10-4/G.992.1 – ATU-R MS message NPar(2) bit definitions** + +| NPar(2) bit | Definition | +|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| R-ACK1 | Signifies that the ATU-C shall send C-PILOT1A, C-QUIET3A, C-PILOT2 and C-QUIET5 during transceiver training. | +| R-ACK2 | Signifies that the ATU-C shall send C-PILOT1, C-PILOT2 and C-PILOT3 during transceiver training. | +| Tones 1 to 32 | See B.3.2.2. | +| STM | Set to ONE if and only if this bit was set to ONE in both the last previous CL message and the last previous CLR message. Signifies that the ATU-C and ATU-R shall be configured for STM bit sync transport. | +| ATM | Set to ONE if and only if this bit was set to ONE in both the last previous CL message and the last previous CLR message. Signifies that the ATU-C and ATU-R shall be configured for ATM cell transport. | +| EOC-Clear | Set to ONE, if and only this bit was set to ONE in both last previous CL message and last previous CLR message. Signifies that both ATU-C and ATU-R may transmit and receive G.997.1 OAM frames. | +| DBM | See C.7.3.2. | + +One and only one of the R-ACK1 and R-ACK2 bits shall be set to ONE in an MS message sent from the ATU-R. If both bits are enabled in the CL and CLR message, the R-ACK1 or R-ACK2 selection is at the ATU-R's discretion. + +One and only one of the STM and ATM bits shall be set to ONE in an MS message sent from the ATU-R. If both bits are enabled in the CL and CLR message, the STM or ATM selection is at the ATU-R's discretion. + +## 10.4 Transceiver training – ATU-C + +This subclause and 10.5 describe the signals transmitted during transceiver training by the ATU-C and ATU-R, respectively. Synchronization of the mutual training begins with the transmission of R-REVERB1 (see 10.5.2), and is maintained throughout training by both transceivers counting the number of symbols from that point on. + +QUIET signals are defined as zero output voltage from the DAC of Figures 5-1 through 5-4. + +![Timing diagram of transceiver training (10.4-10.5) showing signal sequences for ATU-C and ATU-R over time.](d04c50badc78d5ba47bf4e352af4a754_img.jpg) + +The diagram illustrates the timing of signals for ATU-C and ATU-R during transceiver training. The ATU-C signal sequence starts with C-FLAG2 (G.994.1) or C-GALF2 (G.994.1), followed by C-QUIET2 (10.4.1). This is followed by a period containing C-PILOT1 (10.4.2), C-PILOT1A and C-QUIET3A (10.4.3 & 4), C-REVERB1 (10.4.5), C-PILOT2 (10.4.6), C-ECT (10.4.7), C-REVERB2 (10.4.8), C-QUIET5 (10.4.9), C-PILOT3 (10.4.10), and C-REVERB3 (10.4.11). The ATU-R signal sequence starts with R-FLAG2 (G.994.1) or R-GALF2 (G.994.1), followed by R-QUIET2 (10.5.1), R-REVERB1 (10.5.2), R-QUIET3 (10.5.3), R-ECT (10.5.4), and R-REVERB2 (10.5.5). A dashed arrow points from the ATU-C sequence to the ATU-R sequence, labeled (Note), indicating synchronization. The time axis is labeled 'Time →'. + +| ATU-C | | | | | | | | | +|----------------------|----------------------|-----------------------------------------------|-----------------------|----------------------|-------------------|-----------------------|-----------------------|------------------------| +| C-FLAG2
(G.994.1) | C-QUIET2
(10.4.1) | C-PILOT1
(10.4.2) | C-REVERB1
(10.4.5) | C-PILOT2
(10.4.6) | C-ECT
(10.4.7) | C-REVERB2
(10.4.8) | C-QUIET5
(10.4.9) | C-REVERB3
(10.4.11) | +| C-GALF2
(G.994.1) | | C-PILOT1A
and
C-QUIET3A
(10.4.3 & 4) | | | | | C-PILOT3
(10.4.10) | | + +↓ ↑ (Note) + +| ATU-R | | | | | | +|----------------------|----------------------|-----------------------|----------------------|-------------------|-----------------------| +| R-FLAG2
(G.994.1) | R-QUIET2
(10.5.1) | R-REVERB1
(10.5.2) | R-QUIET3
(10.5.3) | R-ECT
(10.5.4) | R-REVERB2
(10.5.5) | +| R-GALF2
(G.994.1) | | | | | | + +T1532630-99 + +Time → + +Timing diagram of transceiver training (10.4-10.5) showing signal sequences for ATU-C and ATU-R over time. + +NOTE – Because the ATU-C and ATU-R states are synchronized from this point on, no more "cause-and-effect" arrows are shown. + +**Figure 10-2/G.992.1 – Timing diagram of transceiver training (10.4-10.5)** + +### 10.4.1 C-QUIET2 + +C-QUIET2 begins at the termination of either C-FLAG2 or C-GALF2 (see Recommendation G.994.1). + +The minimum duration of C-QUIET2 is 128 symbols. The maximum duration of C-QUIET2 is 2048 symbols. + +The state that the ATU-C enters following C-QUIET2 depends upon parameters negotiated in the G.994.1 procedure. + +### 10.4.2 C-PILOT1 + +During C-PILOT1, the ATU-C shall measure the aggregate received upstream power on a subset of the subcarriers transmitted during R-REVERB1, and thereby calculate a downstream PSD (see 10.4.5). + +Within 16 symbols after detection of the first symbol of R-REVERB1 the ATU-C shall start a timer: this establishes synchronization of the subsequent transitions between states at ATU-C and ATU-R. After 512 symbols the ATU-C shall go to C-REVERB1. Thus the minimum duration of C-PILOT is 512 symbols, but it will exceed this by the round-trip propagation and signal-processing time plus the amount of time required by ATU-R to detect C-PILOT1 and respond by transmitting R-REVERB1 (see 10.5.2). + +C-PILOT1 is a single frequency sinusoid at $f_{C-PILOT1}$ defined as: + +$$X_k = \begin{cases} 0, & k \neq n_{C-PILOT1}, 0 \leq k \leq 256 \\ A_{C-PILOT1}, & k = n_{C-PILOT1} \end{cases}$$ + +with $k = n_{C-PILOT1}$ defined in Annexes A, B and C. $A_{C-PILOT1}$ shall be such that the transmit power level is $-3.65$ dBm. The duration of C-PILOT1 can be up to 4436 symbols. + +C-REVERB1 follows C-PILOT1. + +For Annex A, see A.1.1. + +For Annex B, see B.3.6. + +For Annex C, see C.7.4.1. + +#### 10.4.3 C-PILOT1A + +C-PILOT1A is the same transmitted signal as C-PILOT1 (10.4.2). The duration of C-PILOT1A can be up to 4000 symbols. The exact duration of C-PILOT1A depends upon the duration of R-QUIET2. + +Within 16 symbols after detection of the first symbol of R-REVERB1 the ATU-C shall start a timer (this establishes synchronization of the subsequent transitions between states at the ATU-C and ATU-R) and shall proceed to C-QUIET3A. + +An ATU-C implementation which would like to know that an ATU-R will acquire pilot lock prior to the start of R-REVERB1 can detect the length of R-QUIET2. + +C-QUIET3A follows C-PILOT1A. + +#### 10.4.4 C-QUIET3A + +Within 512 to 516 symbols after detection of the first symbol of R-REVERB1, the ATU-C shall go to C-REVERB1. Thus the minimum duration of C-QUIET3A is 512-16 (496) symbols, the maximum is 516 symbols. The total duration of C-QUIET3A and C-PILOT1A is a minimum of 512 symbols, but it will exceed this (up to a maximum duration of 4436 symbols) by the round-trip propagation and signal-processing time plus the amount of time required by ATU-R to detect C-PILOT1A and respond by transmitting R-REVERB1. + +C-REVERB1 follows C-QUIET3A. + +#### 10.4.5 C-REVERB1 + +C-REVERB1 is a signal that allows the ATU-C and ATU-R receiver to adjust its automatic gain control (AGC) to an appropriate level. The data pattern used in C-REVERB1 shall be the pseudo-random downstream sequence (PRD), $d_n$ for $n = 1$ to 512, defined in 7.11.3 and repeated here for convenience: + +$$\begin{aligned} d_n &= 1 && \text{for } n = 1 \text{ to } 9 \\ &= d_{n-4} \oplus d_{n-9} && \text{for } n = 10 \text{ to } 512 \end{aligned} \tag{10-1}$$ + +The bits shall be used as follows: the first pair of bits ( $d_1$ and $d_2$ ) is used for the DC and Nyquist subcarriers (the power assigned to them is, of course, zero, so the bits are effectively ignored); then the first and second bits of subsequent pairs are used to define the $X_i$ and $Y_i$ for $i = 1$ to 255 as defined in Table 7-13. + +The period of PRD is only 511 bits, so $d_{512}$ shall be equal to $d_1$ . The bits $d_1$ to $d_9$ shall be re-initialized for each symbol, so each symbol of C-REVERB1 is identical. + +Bits 129 and 130, which modulate the pilot carrier, shall be overwritten by $\{0,0\}$ : generating the $\{+,+\}$ constellation. + +The duration of C-REVERB1 is 512 (repeating) symbols without cyclic prefix. + +#### **10.4.5.1 Power Cut-back** + +The nominal transmit PSD for C-REVERB1 is $-40$ dBm/Hz (i.e. $-3.65$ dBm total transmit power in any 4.3125 kHz wide sliding window over the used passband). If, however, the total upstream power measured during R-REVERB1 exceeds the levels defined in the appropriate Annex (A, B or C), the transmit PSD shall be reduced to a level of $-40 - 2n_{\text{PCB}}$ dBm/Hz as defined in that annex with $n_{\text{PCB}} = 0$ to 6. + +For Annexes A and C, see A.3.1. + +For Annex B, see B.3.3. + +#### **10.4.6 C-PILOT2** + +The C-PILOT2 signal is the same as C-PILOT1; the duration is 3072 symbols. C-ECT follows C-PILOT2. + +#### **10.4.7 C-ECT** + +C-ECT is a vendor-defined signal that is used to train the echo canceller at ATU-C for overlapped spectrum implementations. Vendors of FDM versions have complete freedom to define their C-ECT signal. The duration of C-ECT, however, is fixed at 512 symbols. The receiver at ATU-R should ignore this signal. C-REVERB2 follows C-ECT. + +NOTE – The level of the ADSL signal in the frequency band from 0 to about 10 kHz that leaks through the POTS low-pass filter is tightly limited (see Annex E). Therefore it is recommended that subcarriers 1-4 not be used for C-ECT, or, at least, that they be transmitted at a much lower level. + +Annex B supplemental information appears in B.3.11. + +#### **10.4.8 C-REVERB2** + +C-REVERB2 is a signal that allows the ATU-R receiver to perform synchronization and to train any receiver equalizer. C-REVERB2 is the same as C-REVERB1 (see 10.4.5). The duration of C-REVERB2 is 1536 (repeating) symbols without cyclic prefix. The state following C-REVERB2 depends upon negotiated parameters in Recommendation G.994.1. + +#### **10.4.9 C-QUIET5** + +The duration of C-QUIET5 is 512 symbols. C-REVERB3 follows C-QUIET5. + +#### **10.4.10 C-PILOT3** + +C-PILOT3 signal is the same as C-PILOT1 (10.4.2). The duration of C-PILOT3 is 512 symbols. + +C-REVERB3 follows C-PILOT3. + +#### **10.4.11 C-REVERB3** + +C-REVERB3 is a second training signal, which allows the ATU-R receiver to perform or maintain synchronization and to further train any receiver equalizer. C-REVERB3 is the same as C-REVERB2 (see 10.4.8). The duration of C-REVERB3 is 1024 (repeating) symbols without cyclic prefix. This is the last segment of transceiver training. C-SEGUE1 follows immediately. + +### **10.5 Transceiver training – ATU-R** + +#### **10.5.1 R-QUIET2** + +R-QUIET2 begins at the termination of either R-FLAG2 or R-GALF2 (see Recommendation G.994.1). + +The minimum duration of R-QUIET2 is 128 DMT symbols after the detection of C-PILOT1/1A. The ATU-R shall progress to R-REVERB1 only after it has detected any part of C-PILOT1/1A that is needed for reliable detection. The maximum duration of R-QUIET2 of 8000 symbols. + +Loop timing is defined as the combination of the slaving of an ADC clock to the received signal (i.e. to the other transceiver's DAC clock), and tying the local DAC and ADC clocks together. Loop timing shall always be performed at the ATU-R. Loop timing shall be acquired during the period that begins with the start of R-QUIET2 and ends before the last 512 symbols of R-REVERB1. An ATU-C may train its equalizer during the last 512 symbols of R-REVERB1. Such equalizer training, at the ATU-C, requires sufficient sampling clock stability at the ATU-R transmitter. After loop timing is acquired at ATU-R, the ATU-R shall reacquire loop timing after a period with free running timing (i.e. no C-PILOT over maximum 512 symbols) within 512 symbols after the C-PILOT reappearing. This applies to C-QUIET5 and may also apply to C-QUIET3A and C-ECT. + +NOTE – The delay in the ATU-R in going from R-QUIET2 to R-REVERB1 is to allow the possibility that the ATU-R may fully synchronize its time base before sending R-REVERB1 and the possibility that the implementation of G.994.1 and G.992.1 may be in separate entities. + +### 10.5.2 R-REVERB1 + +R-REVERB1 is used to allow the ATU-C to: + +- measure the upstream wideband power in order to adjust the ATU-C transmit power level; +- adjust its receiver gain control; +- synchronize its receiver and train its equalizer. + +The bits shall be used as defined in Annexes A, B and C. + +For Annex A, see A.3.5. + +For Annex B, see B.3.7. + +For Annex C, see C.7.5.2. + +The period of PRD is only 63 bits, so $d_{64}$ shall be equal to $d_1$ . + +The $d_1$ to $d_6$ shall be re-initialized for each symbol, so each symbol of R-REVERB1 uses the same data. + +The nominal transmit PSD for R-REVERB1 and all subsequent upstream signals is $-38$ dBm/Hz (i.e. $-1.65$ dBm total transmit power in any 4.3125 kHz wide sliding window over the used passband). + +R-REVERB1 is a periodic signal, without cyclic prefix, that is transmitted consecutively for 4096 symbols. The first 512 symbols coincide with C-QUIET3 or C-PILOT1 signal in time, the second 512 symbols coincide with C-REVERB1, and the last 3072 symbols coincide with C-PILOT2. R-QUIET3 immediately follows R-REVERB1. + +### 10.5.3 R-QUIET3 + +The duration of R-QUIET3 is 2048 symbols, of which the first 512 symbols coincide with C-ECT in time, and the next 1536 symbols coincide with C-REVERB2. The final symbol of R-QUIET3 may be shortened by any number of samples to accommodate transmitter-to-receiver frame alignment. R-ECT immediately follows R-QUIET3. + +### 10.5.4 R-ECT + +R-ECT, similar to C-ECT, is a vendor-defined signal that may be used to train an echo canceller at ATU-R. Vendors of FDM versions have absolute freedom to define R-ECT signal. The duration of R-ECT, however, is fixed at 512 DMT symbols. The receiver at ATU-C ignores this signal. R-REVERB2 follows R-ECT. + +NOTE – The level of the ADSL signal in the frequency band from 0 to about 10 kHz that leaks through the POTS low-pass filter is tightly limited (see Annex E). Therefore it is recommended that subcarriers 1-4 not be used for R-ECT, or, at least, that they be transmitted at a much lower level. + +Annex B supplemental information appears in B.3.11. + +### 10.5.5 R-REVERB2 + +The signal *R-REVERB2* is the same as *R-REVERB1* (see 10.5.2); it can be used by ATU-C to perform timing recovery and receiver equalizer training. The duration of *R-REVERB2* shall be between 1024 and 1056 symbols. This signal is the last segment of transceiver training. ATU-R then begins channel analysis and starts transmitting *R-SEGUE1*. + +## 10.6 Channel analysis (ATU-C) + +![Timing diagram of channel analysis (10.6-10.7) showing the sequence of signals transmitted by ATU-C and ATU-R over time. ATU-C transmits C-SEGUE1, then a block containing C-RATES1, C-CRC1, C-MSG1, and C-CRC2, followed by C-MEDLEY and C-REVERB4. ATU-R transmits R-SEGUE1, R-REVERB3, R-SEGUE2, then a block containing R-RATES1, R-CRC1, R-MSG1, and R-CRC2, followed by R-MEDLEY and R-REVERB4. A downward arrow indicates the interaction between ATU-C and ATU-R sequences.](b4c825454b7a89b4d7744e4f45521174_img.jpg) + +ATU-C + +| | | | | +|----------------------|------------------------------------------------------------------|----------------------|-----------------------| +| C-SEGUE1
(10.6.1) | C-RATES1,
C-CRC1,
C-MSG1, and
C-CRC2
(10.6.2-10.6.5) | C-MEDLEY
(10.6.6) | C-REVERB4
(10.8.1) | +|----------------------|------------------------------------------------------------------|----------------------|-----------------------| + +↓ + +ATU-R + +| | | | | | | +|----------------------|-----------------------|----------------------|------------------------------------------------------------------|----------------------|-----------------------| +| R-SEGUE1
(10.7.1) | R-REVERB3
(10.7.2) | R-SEGUE2
(10.7.3) | R-RATES1,
R-CRC1,
R-MSG1, and
R-CRC2
(10.7.4-10.7.7) | R-MEDLEY
(10.7.8) | R-REVERB4
(10.7.9) | +|----------------------|-----------------------|----------------------|------------------------------------------------------------------|----------------------|-----------------------| + +Time → + +Timing diagram of channel analysis (10.6-10.7) showing the sequence of signals transmitted by ATU-C and ATU-R over time. ATU-C transmits C-SEGUE1, then a block containing C-RATES1, C-CRC1, C-MSG1, and C-CRC2, followed by C-MEDLEY and C-REVERB4. ATU-R transmits R-SEGUE1, R-REVERB3, R-SEGUE2, then a block containing R-RATES1, R-CRC1, R-MSG1, and R-CRC2, followed by R-MEDLEY and R-REVERB4. A downward arrow indicates the interaction between ATU-C and ATU-R sequences. + +**Figure 10-3/G.992.1 – Timing diagram of channel analysis (10.6-10.7)** + +During channel analysis the synchronization between ATU-C and ATU-R may be broken during *R-REVERB3*, which has an indefinite duration; this potential timeout is described in 10.7.2. Furthermore, if during channel analysis any CRC check sum indicates an error in any of the control data, this shall trigger a reset to *C-SILENT1* (see Recommendation G.994.1). + +### 10.6.1 C-SEGUE1 + +Except for the pilot tone, *C-SEGUE1* shall be generated from a tone-by-tone 180 degree phase reversal of *C-REVERB1* (i.e. + maps to –, and – maps to +, for each of the 4-QAM signal constellation). The duration of *C-SEGUE1* is 10 (repeating) symbol periods. Following *C-SEGUE1*, ATU-C enters state *C-RATES1*. + +### 10.6.2 C-RATES1 + +*C-RATES1* is the first ATU-C signal for which a cyclic prefix (defined in 7.12) is used. The purpose of *C-RATES1* is to transmit four options for data rates and formats to the ATU-R. Each option consists of three fields: + +- $B_F$ lists the number of bytes in the fast buffer for each of AS0, AS1, AS2, AS3, LS0, LS1, LS2, LS0 (upstream), LS1 (upstream), LS2 (upstream) channels, in that order; $B_F$ has a total of $80 (= 10 \times 8)$ bits. The first 8 bits of $B_F$ specify the number of bytes in AS0, the second 8 bits specify the number of bytes in AS1, and so on. Each byte of $B_F$ is transmitted with least significant bit first. +- $B_I$ similarly lists the number of bytes in the interleaved buffer. In order to support data rates greater than 8 Mbit/s, the $B_I$ field is eight bits. + +- $\{RS_F, RS_I, S, I, FS(LS2)\}$ is a ten-byte quantity comprising (one byte each): + - the $RS_F$ field, containing $RS_F$ , the number of parity bytes per symbol in the downstream fast buffer, with $0 \leq RS_F \leq 63$ and $RS_F$ equal to $R_F$ ( $R_F$ is defined in 7.4.1.2.1); + - the $RS_I$ field, containing the value of $RS_I$ , the number of parity bytes per symbol in the downstream interleave buffer, with $0 \leq RS_I \leq 63$ and $RS_I$ equal to $R_I/S$ ( $R_I$ and $S$ are defined in 7.4.1.2.2); + - the $S$ field, containing the value of $S$ , the number of symbols per codeword (downstream), with $0 \leq S \leq 63$ ; + - the $I$ field, containing the eight least significant bits $I_7$ to $I_0$ of the downstream interleave depth in codewords, with $0 \leq I \leq 128$ ; + - the $FS(LS2)$ field is a field of eight zeros; + - the same five quantities $\{RS_F, RS_I, S, I, FS(LS2)\}$ in the upstream direction (one-byte each, in that order). + +The four options are transmitted in order of decreasing preference. C-RATES1 is preceded by a 4-byte prefix of $\{01010101\ 01010101\ 01010101\ 01010101_2\}$ . Table 10-5 summarizes C-RATES1. + +**Table 10-5/G.992.1 – C-RATES1** + +| | Prefix | Option 1 | | | Option 2 | | | Option 3 | | | Option 4 | | | +|-----------------|--------|----------|-------|--------|----------|-------|--------|----------|-------|--------|----------|-------|--------| +| | | $B_F$ | $B_I$ | $RRSI$ | $B_F$ | $B_I$ | $RRSI$ | $B_F$ | $B_I$ | $RRSI$ | $B_F$ | $B_I$ | $RRSI$ | +| Number of bytes | 4 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | + +Only one bit of information is transmitted in each symbol of C-RATES1: a zero bit is encoded to one symbol of C-REVERB1 and a one bit is encoded to one symbol of C-SEGUE1. Since there are a total of 992 bits of C-RATES1 information, the duration of C-RATES1 is 992 symbols. The 992 bits are to be transmitted in the order shown in Table 10-5, with the least significant bit first. That is, the least significant bit of option 1, $B_F$ , is to be transmitted during the 33rd symbol of C-RATES1, after the prefix. Following C-RATES1, the ATU-C shall enter state C-CRC1. + +### 10.6.3 C-CRC1 + +C-CRC1 is a cyclic redundancy check for detection of errors in the reception of C-RATES1 at the ATU-R. The CRC bits are computed from the C-RATES1 bits using the equation: + +$$c(D) = a(D) D^{16} \text{ modulo } g(D), \quad (10-2)$$ + +where: + +$$a(D) = a_0 D^{959} + a_1 D^{958} \dots + a_{959} \quad (10-3)$$ + +is the message polynomial formed from the 960 bits of C-RATES1, with $a_0$ the least significant bit of the first byte of C-RATES1 (i.e. option 1 $B_F$ ); + +$$g(D) = D^{16} + D^{12} + D^5 + 1 \quad (10-4)$$ + +is the CRC generator polynomial, and + +$$c(D) = c_0 D^{15} + c_1 D^{14} \dots + c_{14} D + c_{15} \quad (10-5)$$ + +is the CRC check polynomial. + +The 16 bits $c_0$ - $c_{15}$ are transmitted ( $c_0$ first and $c_{15}$ last) in 16-symbol periods using the method described in 10.6.2. Following C-CRC1, the ATU-C shall enter state C-MSG1. + +### 10.6.4 C-MSG1 + +C-MSG1 transmits a 48-bit message signal to the ATU-R. This message includes vendor identification, ATU-C transmit power level used, trellis code option, echo canceller option, etc. The message, $m$ , is defined by: + +$$m = \{m_{47}, m_{46}, \dots, m_1, m_0\} \quad (10-6)$$ + +with $m_0$ being transmitted first. The message components are defined in the following subclauses, and their assigned positions within the composite message, $m$ , are defined in Table 10-6. + +A total of 48 symbol periods are used to communicate the 48-bit message, using the encoding method described in 10.6.2. Following C-MSG1, the ATU-C shall enter signalling state C-CRC2. + +**Table 10-6/G.992.1 – Assignment of 48 bits of C-MSG1** + +| Suffix(ces) of $m_i$ (Note 1) | Parameter (Note 3) | +|-------------------------------|-------------------------------------------------------------------| +| 47-44 | Minimum required downstream SNR margin at initialization (Note 2) | +| 43-18 | Reserved for future use | +| 17 | Trellis coding option | +| 16 | Overlapped spectrum option (Note 4) | +| 15 | Unused (shall be set to "1") | +| 14-12 | Reserved for future use | +| 11 | NTR | +| 10-9 | Framing mode | +| 8-6 | Transmit PSD during initialization | +| 5, 4 | Reserved | +| 3, 2, 1, 0 | Maximum numbers of bits per subcarrier supported | + +NOTE 1 – Within the separate fields the least significant bits have the lowest subscripts. +NOTE 2 – A positive number of dB; binary coded 0-15 dB. +NOTE 3 – All reserved bits shall be set to "0". +NOTE 4 – The initialization sequence allows for interworking of overlapped and non-overlapped spectrum implementations. Therefore, this indication is for information only. + +#### 10.6.4.1 Minimum required SNR margin – Bits 47-44 + +Binary coded 0 to 15 dB. + +#### 10.6.4.2 Trellis coding option – Bit 17 + +$m_{17} = 0$ indicates no trellis coding capability, $m_{17} = 1$ indicates trellis coding capability. + +#### 10.6.4.3 Overlapped Spectrum option – Bit 16 + +$m_{16} = 0$ indicates no echo cancellation, $m_{16} = 1$ indicates echo cancellation. + +#### 10.6.4.4 Unused – Bit 15 + +$m_{15}$ shall be set to "1". + +#### 10.6.4.5 NTR – Bit 11 + +$m_{11} = 1$ indicates that the ATU-C will use indicator bits ib23 to ib20 as defined in 7.3.2 for the transport of the NTR. + +#### 10.6.4.6 Framing mode – Bits 10, 9 + +$m_{10}$ and $m_9$ are used by the ATU-C to indicate which of the four framing structures is to be used (see 7.4). The lowest framing structure indicated by the ATU-C or ATU-R shall be used. + +#### 10.6.4.7 Transmit PSD during initialization – Bits 8, 7, 6 + +The ATU-C shall report the level of C-REVERB1 chosen as a result of the calculation described in 10.4.5. The encoding rules for $m_8$ , $m_7$ , $m_6$ are shown in Table 10-7. + +**Table 10-7/G.992.1 – C-MSG1 encoding rules for transmit PSD during C-REVERB1** + +| $m_8$ | $m_7$ | $m_6$ | PSD dBm/Hz | +|-------|-------|-------|------------| +| 1 | 1 | 1 | -40 | +| 1 | 1 | 0 | -42 | +| 1 | 0 | 1 | -44 | +| 1 | 0 | 0 | -46 | +| 0 | 1 | 1 | -48 | +| 0 | 1 | 0 | -50 | +| 0 | 0 | 1 | -52 | + +NOTE – The rules for selecting a reduced PSD level depend on the service option, and are defined in Annexes A, B and C; the levels themselves are independent of the service option, and are defined here. + +#### 10.6.4.8 Maximum numbers of bits per subcarrier supported – Bits 3-0 + +The $N_{\text{downmax}}$ (transmit) capability shall be binary encoded onto $\{m_3, \dots, m_0\}$ (e.g. $1101_2 = 13$ ). The maximum number of bits for the upstream data, $N_{\text{upmax}}$ , that the ATU-C receiver can support need not be signalled to the ATU-R; it will be implicit in the bits and gains message, C-B&G, which is transmitted after channel analysis. + +### 10.6.5 C-CRC2 + +C-CRC2 is a cyclic redundancy check for detection of errors in the reception of C-MSG1 at the ATU-R. The CRC generator polynomial is as defined in 10.6.3. The CRC message polynomial is as constructed in 10.6.3, with $m_0$ corresponding to $a_0$ and $m_{47}$ corresponding to $a_{47}$ . The CRC check polynomial is generated in the same way as defined in 10.6.3. These 16 bits are transmitted in 16-symbol periods using the method described in 10.6.2. Following C-CRC2, the ATU-C shall enter signalling state C-MEDLEY. + +### 10.6.6 C-MEDLEY + +C-MEDLEY is a wideband pseudo-random signal used for estimation at the ATU-R of the downstream SNR. The data to be transmitted are derived from the pseudo-random sequence, PRD, and modulated as defined in 10.4.5. In contrast to C-REVERB1, however, the cyclic prefix is used and the data sequence continues from one symbol to the next (i.e. $d_1$ to $d_9$ are not re-initialized for each symbol); since PRD is of length 511, and 512 bits are used for each symbol, the subcarrier vector for C-MEDLEY therefore changes from one symbol period to the next. The pilot subcarrier is overwritten by the $(+,+)$ signal constellation. C-MEDLEY is transmitted for 16 384 symbol periods. + +Following C-MEDLEY the ATU-C shall enter the state C-REVERB4. + +## 10.7 Channel analysis (ATU-R) + +During channel analysis there are two situations where the ATU-R will reset itself to R-SILENT0 (see Recommendation G.994.1): a timeout and a detected error in the received control data. A timeout occurs if the time in R-REVERB3 exceeds the limit of 4000 symbols. Also, if any C-CRC checksum indicates there is an error in the received control data, then it shall trigger a reset to R-SILENT0 (see Recommendation G.994.1). + +### 10.7.1 R-SEGUE1 + +R-SEGUE1 is generated from a tone-by-tone 180 degree phase reversal of R-REVERB1 (i.e. + maps to -, and - maps to ++, for each of the 4-QAM signal constellation). The duration of R-SEGUE1 is 10-symbol periods. Following R-SEGUE1 the ATU-R shall enter state R-REVERB3. + +### 10.7.2 R-REVERB3 + +R-REVERB3 is similar to R-REVERB1 (see 10.5.2); the only difference is that R-REVERB3 is the first ATU-R signal with the addition of a cyclic prefix to every symbol (defined in 8.11.4). The duration of R-REVERB3 is not fixed but has a maximum of 4000 symbols. If C-CRC2 is not detected within 4000 symbols, the ATU-R shall timeout and reset to R-SILENT0 (see Recommendation G.994.1). After detection of C-RATES1 through C-CRC2, the ATU-R shall continue to send R-REVERB3 for 20 additional symbols before entering R-SEGUE2. + +### 10.7.3 R-SEGUE2 + +The signal R-SEGUE2 is similar to R-SEGUE1 (see 10.7.1); the only difference is the addition of the cyclic prefix. Following R-SEGUE2 the ATU-R shall enter state R-RATES1. + +### 10.7.4 R-RATES1 + +See Table 10-8. + +**Table 10-8/G.992.1 – R-RATES1** + +| | Prefix | Option 1 | | | Option 2 | | | Option 3 | | | Option 4 | | | +|-----------------|--------|----------|-------|--------|----------|-------|--------|----------|-------|--------|----------|-------|--------| +| | | $B_F$ | $B_I$ | $RRSI$ | $B_F$ | $B_I$ | $RRSI$ | $B_F$ | $B_I$ | $RRSI$ | $B_F$ | $B_I$ | $RRSI$ | +| Number of bytes | 4 | 3 | 3 | 5 | 3 | 3 | 5 | 3 | 3 | 5 | 3 | 3 | 5 | + +The purpose of R-RATES1 for the upstream channel is the same as that of C-RATES1 for the downstream channel (see 10.6.2). Each option consists of three fields: + +- $B_F$ lists the number of bytes in the fast buffer for each of LS0, LS1, LS2, in that order; $B_F$ has a total of 24 ( $= 3 \times 8$ ) bits. The first 8 bits of $B_F$ specify the number of bytes in LS0, the second 8 bits specify the number of bytes in LS1, and so on. Each byte of $B_F$ is transmitted with least significant bit first; +- $B_I$ similarly lists the number of bytes in the interleaved buffer; +- $\{RS_F, RS_I, S, I, FS(LS2)\}$ is a five-byte quantity comprising: + - $RS_F$ , the number of parity bytes per symbol in the fast buffer (upstream); + - $RS_I$ , the number of parity bytes per symbol in the interleaved buffer (upstream); + - $S$ , the number of symbols per codeword (upstream); + - $I$ , the interleaved depth (upstream) in codewords for the interleaved buffer; + +- FS(LS2) is a field of eight zeros. + +The four options are transmitted in order of decreasing preference. For the present system, ATU-C has control over all the data rates, so R-RATES1 is copied from the appropriate fields of C-RATES1. + +Only one bit of information is transmitted during each symbol period of R-RATES1: a zero bit is encoded to one symbol of R-REVERB1 and a one bit is encoded to one symbol of R-SEGUE1 (with addition of cyclic prefix). Since there are a total of 384 bits of RATES1 information, the length of R-RATES1 is 384 symbols. The 384 bits are to be transmitted in the order shown in Table 10-8, with the least significant bit first. That is, the least significant bit of option 1, $B_F$ (see Table 10-8), is to be transmitted during the 33rd symbol of R-RATES1, after the prefix. Following R-RATES1, the ATU-R shall enter state R-CRC1. + +### 10.7.5 R-CRC1 + +R-CRC1 is a cyclic redundancy check intended for detection of an error in the reception of R-RATES1 at the ATU-C. The CRC polynomial $c(D)$ and generator polynomial $g(D)$ are the same as for C-CRC1 (see 10.6.3). The 16 bits $c_0$ to $c_{15}$ are transmitted ( $c_0$ first and $c_{15}$ last) in 16-symbol periods using the same method as R-RATES1 (see 10.7.4). Following R-CRC1, the ATU-R shall enter state R-MSG1. + +### 10.7.6 R-MSG1 + +R-MSG1 transmits a 48-bit message signal to the ATU-C. This message includes vendor identification, trellis code option, echo canceller option, etc. The message, $m$ , is defined by: + +$$m = \{m_{47}, m_{46}, \dots, m_1, m_0\} \quad (10-7)$$ + +with $m_0$ , the least significant bit, being transmitted first. The message components are defined in the following subclauses, and their assigned positions within the composite message, $m$ , are defined in Table 10-9. + +A total of 48-symbol periods are used to communicate the 48-bit message, using the encoding method described in 10.7.4. Following R-MSG1, the ATU-R shall enter signalling state R-CRC2. + +**Table 10-9/G.992.1 – Assignment of 48 bits of R-MSG1** + +| Suffix(ces) of $m_i$ (Note 1) | Parameter (Note 2) | +|-------------------------------|-------------------------------------------------------| +| 47-18 | Reserved for future use | +| 17 | Trellis coding option | +| 16 | Overlapped spectrum option (Note 3) | +| 15 | Unused (shall be set to "1") | +| 14 | Support of higher bit rates ( $S = 1/2$ ) (see 7.6.3) | +| 13 | Support of dual latency downstream | +| 12 | Support of dual latency upstream | +| 11 | Network Timing Reference | +| 10, 9 | Framing mode | + +**Table 10-9/G.992.1 – Assignment of 48 bits of R-MSG1 (concluded)** + +| Suffix(ces) of $m_i$ (Note 1) | Parameter (Note 2) | +|-------------------------------|--------------------------------------------------| +| 8-4 | Reserved for future use | +| 3-0 | Maximum numbers of bits per subcarrier supported | + +NOTE 1 – Within the separate fields the least significant bits have the lowest subscripts. +NOTE 2 – All reserved bits shall be set to "0". +NOTE 3 – The initialization sequence allows for interworking of overlapped and non-overlapped spectrum implementations. Therefore, this indication is for information only. + +#### 10.7.6.1 Trellis coding option – Bit 17 + +$m_{17} = 0$ indicates no trellis coding capability; $m_{17} = 1$ indicates trellis coding capability. + +#### 10.7.6.2 Echo cancellation option – Bit 16 + +$m_{16} = 0$ indicates no echo cancellation; $m_{16} = 1$ indicates echo cancellation. + +#### 10.7.6.3 Unused – Bit 15 + +$m_{15}$ shall be set to "1". + +#### 10.7.6.4 Framing Mode – Bits 10, 9 + +$m_{10}$ and $m_9$ are used by the ATU-R to indicate which of the four framing structures is to be used (see 8.4). The lowest framing structure indicated by the ATU-C or ATU-R shall be used. + +#### 10.7.6.5 Network timing reference – Bit 4 + +$m_4 = 1$ indicates the ATU-R supports reconstruction of the network timing reference from the downstream indicator bits 23-20. + +#### 10.7.6.6 Maximum numbers of bits per subcarrier supported – Bits 3-0 + +The $N_{upmax}$ (transmit) capability is encoded onto $\{m_3, \dots, m_0\}$ with a conventional binary representation (e.g. $1101_2 = 13$ ). + +NOTE – The maximum number of bits for the downstream data, $N_{downmax}$ , that the ATU-R receiver can support need not be signalled to the ATU-C; it will be implicit in the bits and gains message, R-B&G, which is transmitted after channel analysis. + +### 10.7.7 R-CRC2 + +R-CRC2 is a cyclic redundancy check for detection of errors in the reception of R-MSG1 at the ATU-C. The CRC generator polynomial is as defined in 10.7.5. The CRC message polynomial is as constructed in 10.7.5, with $m_0$ corresponding to $a_0$ and $m_{47}$ corresponding to $a_{47}$ . The CRC check polynomial is generated in exactly the same way as described in 10.7.5. These 16 bits are transmitted in 16-symbol periods using the method described in 10.7.5. Following R-CRC2, the ATU-R shall enter state R-MEDLEY. + +### 10.7.8 R-MEDLEY + +R-MEDLEY is a wideband pseudo-random signal used for estimation of the upstream SNR at the ATU-C. The data to be transmitted are derived from the pseudo-random sequence PRU defined in 10.5.2. In contrast to R-REVERB1, however, the cyclic prefix is used and the data sequence continues from one symbol to the next (i.e. $d_1$ to $d_6$ are not re-initialized for each symbol). Because the sequence is of length 63, and 64 bits are used for each symbol, the subcarrier vector for + +R-MEDLEY changes from one symbol period to the next. R-MEDLEY is transmitted for 16 384 symbol periods. Following R-MEDLEY the ATU-R enters signalling state R-REVERB4. + +For Annex B, see B.3.8. + +For Annex C, see C.7.8.3. + +#### **10.7.9 R-REVERB4** + +R-REVERB4 is the same as R-REVERB3 (see 10.7.2). The duration of R-REVERB4 is 128 symbols. This signal marks the end of channel analysis, and R-SEGUE3 immediately follows R-REVERB4. + +## 10.8 Exchange – ATU-C + +The timing diagram of exchange is shown in Figure 10-4. + +![Timing diagram of exchange between C-REVERB4 (10.8.1) and R-SEGUE3 (10.9.1).](2d548db0b26b7bf33244320322d5ee2c_img.jpg) + +The diagram illustrates the sequence of messages exchanged between a Client (C) and a Remote (R) entity. The Client's sequence starts with C-REVERB4 (10.8.1) and ends with C-SEGUE3 (10.8.16). The Remote's sequence starts with R-SEGUE3 (10.9.1) and ends with R-SEGUE5 (10.9.17). Arrows indicate the flow of messages between the two entities. + +| Client (C) Sequence | Remote (R) Sequence | +|---------------------------------------------------------------------|---------------------------------------------------------------| +| C-REVERB4 (10.8.1) | R-SEGUE3 (10.9.1) | +| C-SEGUE2 (10.8.2) | R-MSG-RA, R-CRC-RA1, R-RATES-RA and R-CRC-RA2 (10.9.2-10.9.5) | +| C-RATES-RA, C-CRC-RA1, C-MSG-RA and C-CRC-RA2 (10.8.3-10.8.6) | R-REVERB-RA (10.9.6) | +| C-REVERB-RA (10.8.7) | R-SEGUE-RA (10.9.7) | +| C-SEGUE-RA (10.8.8) | R-MSG2, R-CRC3, R-RATES2 and R-CRC4 (10.9.8-10.9.11) | +| C-MSG2, C-CRC3, C-RATES2, C-CRC4, C-B&G and C-CRC5 (10.8.9-10.8.14) | R-REVERB5 (10.9.12) | +| C-REVERB5 (10.8.15) | R-SEGUE4 (10.9.13) | +| C-SEGUE3 (10.8.16) | R-B&G and R-CRC5 (10.9.14-10.9.15) | +| | R-REVERB6 (10.9.16) | +| | R-SEGUE5 (10.9.17) | + +Timing diagram of exchange between C-REVERB4 (10.8.1) and R-SEGUE3 (10.9.1). + +T1532640-99 + +Figure 10-4/G.992.1 – Timing diagram of exchange + +During exchange there are two events that shall cause the ATU-C to reset to C-SILENT1 (see Recommendation G.994.1): timeouts and error detection by a CRC checksum. The exchange procedure is partly synchronized between ATU-C and ATU-R, and partly interactive. During the interactive part (C-REVERB4, C-REVERB5, C-REVERB-RA) a timeout shall occur when the time in the C-REVERB4 state exceeds 6000 symbols or when the time in C-REVERB-RA or C-REVERB5 state exceeds 4000 symbols. + +### 10.8.1 C-REVERB4 + +C-REVERB4 is similar to C-REVERB2 (see 10.4.8), the only difference being the addition of a cyclic prefix on every symbol, and a maximum duration of 6000 symbols. C-REVERB4 continues into the exchange procedure, and its duration is not fixed. The timeout features of C-REVERB4 are defined in 10.8.4. + +If the ATU-C does not detect R-CRC-RA2 within 6000 symbols, it shall timeout and reset to C-SILENT1 (see Recommendation G.994.1). After detection of R-SEGUE3 through R-CRC-RA2, the ATU-C shall continue to transmit C-REVERB4 for another 80 symbols before progressing to state C-SEGUE2. + +### 10.8.2 C-SEGUE2 + +The signal C-SEGUE2 is the same as C-SEGUE1 (see 10.6.1), the only difference is the addition of the cyclic prefix. The duration of C-SEGUE2 is 10 symbol periods. Following C-SEGUE2 the ATU-C shall enter state C-RATES-RA to begin a second exchange of rates. + +### 10.8.3 C-RATES-RA + +C-RATES-RA is used to send four new options for transport configuration for both upstream and downstream. C-RATES-RA content is not constrained by previous messages (e.g. C-RATES1 and R-MSG-RA). + +These options will, in general, be closer to the optimum bit rate for the channel than those in C-RATES1, and should be based on the channel information received in R-MSG-RA. + +The format of C-RATES-RA is the same as that of C-RATES1, except that the 4-byte prefix ( $55\ 55\ 55\ 55_{16}$ ) is not transmitted, and the signal is transmitted eight bits per symbol, as defined for C-MSG2 (see 10.8.9). The duration of C-RATES-RA is 120 symbols. + +The $\{RS_F, RS_I, S, I, FS(LS2)\}$ shall have an extended syntax (compared to C-RATES1). It is a ten-byte quantity comprising (one byte each): + +- the $RS_F$ field, containing $RS_F$ , the number of parity bytes per symbol in the downstream fast buffer in bits 5 (MSB) to 0 (LSB) with $RS_F$ equal to $R_F$ ( $R_F$ is defined in 7.4.1.2.1); +- the $RS_I$ field, containing: + - the value of $RS_I$ , the number of parity bytes per symbol in the downstream interleave buffer, in bits 5 (MSB) to 0 (LSB), with $RS_I$ equal to $R_I/S$ ( $R_I$ and $S$ are defined in 7.4.1.2.2); and; + - the most significant bit $B_8$ of $B_I$ (AS0), the number of payload bytes in the AS0 bearer channel in the downstream interleave buffer, in bit 7; + +- the *S* field, containing: + - the value of *S*, the number of downstream symbols per codeword (downstream) in bits 5 (MSB) to 0 (LSB). The necessity to use *S* = 1/2 would be indicated by $K_I + R_I > 255$ (see 7.4.1.2.2 and 7.6.4). Nevertheless, the *S* field bits 5-0 shall be coded {0000002} to indicate *S* = 1/2; + - the two most significant bits, *I*9 and *I*8, of the downstream interleave depth in codewords, *I*, in bits 7 and 6; +- the *I* field, containing the eight least significant bits *I*7 to *I*0 of the downstream interleave depth in codewords; +- the *FS(LS2)* field, containing eight zero bits; +- the same five quantities {*RS*F, *RS*I, *S*, *I*, *FS(LS2)*} in the upstream direction (one-byte each, in that order). + +The four options are transmitted in order of decreasing preference. Table 10-10 summarizes C-RATES-RA and Table 10-11 summarizes the RRSI fields. + +**Table 10-10/G.992.1 – C-RATES-RA** + +| | Option 1 | | | Option 2 | | | Option 3 | | | Option 4 | | | +|-----------------|-----------------------|-----------------------|-------------|-----------------------|-----------------------|-------------|-----------------------|-----------------------|-------------|-----------------------|-----------------------|-------------| +| | B F | B I | RRSI | B F | B I | RRSI | B F | B I | RRSI | B F | B I | RRSI | +| Number of bytes | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 | + +**Table 10-11/G.992.1 – RRSI fields of C-RATES-RA** + +| fields | ← bits → | | | | | | | | +|------------------------|---------------------------------------------------------|-----------------------|---------------------------------|-----------------------|-----------------------|-----------------------|-----------------------|-----------------------| +| | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +| RS F | 0 | 0 | value of RS F | | | | | | +| | | | MSB | | | | | LSB | +| RS I | B 8
(AS0) | 0 | value of RS I | | | | | | +| | | | MSB | | | | | LSB | +| S | I 9 | I 8 | value of S | | | | | | +| | | | MSB | | | | | LSB | +| I | I 7 | I 6 | I 5 | I 4 | I 3 | I 2 | I 1 | I 0 | +| FS(LS2) | value of FS(LS2) set to {00000000 2 } | | | | | | | | + +#### 10.8.4 C-CRC-RA1 + +C-CRC-RA1 is a cyclic redundancy check for detection of errors in the reception of C-RATES-RA at the ATU-R. Its relation to C-RATES-RA1 is the same as that of C-CRC3 to C-MSG2 (see 10.8.10). Its 16 bits shall be transmitted in 2 symbols (see 10.8.9). Following C-CRC-RA1, the ATU-C shall enter state C-MSG-RA. + +### 10.8.5 C-MSG-RA + +C-MSG-RA is the same in format as C-MSG1; the bit assignment is as shown in Table 10-12. + +**Table 10-12/G.992.1 –Assignment of 48 bits of C-MSG-RA** + +| Suffix(ces) of m_i
(Note 1) | Parameter (Note 2) | +|-----------------------------------------------------|-----------------------------------------------------------------------------------------------------| +| 47-44 | New minimum required downstream ATU-R noise margin at initialization | +| 43-38 | Minimum required downstream ATU-R noise margin in steady state (-32 to +31 dB) | +| 37-32 | Maximum allowed downstream ATU-R noise margin at initialization and in steady state (-32 to +31 dB) | +| 31-0 | Reserved for future use | + +NOTE 1 – Within the separate fields the least significant bits have the lowest subscripts. +NOTE 2 – All reserved bits shall be set to "0". +NOTE 3 – Minimum and maximum values are defined in Recommendation G.997.1. +NOTE 4 – Only the minimum and maximum downstream ATU-R noise margins are communicated to the ATU-R. This information is needed for the downstream B&G table calculation at the ATU-R. The minimum and maximum upstream ATU-C noise margins are used locally at the ATU-C for the upstream B&G table calculation. + +The 48 bits are transmitted in 6 symbols (see 10.8.9). Following C-MSG-RA the ATU-C shall enter state C-CRC-RA2. + +### 10.8.6 C-CRC-RA2 + +C-CRC-RA2 is a cyclic redundancy check for detection of errors in the reception of C-MSG-RA at the ATU-R. Its relation to C-MSG-RA is the same as that of C-CRC3 to C-MSG2 (see 10.8.10). Its 16 bits shall be transmitted in 2 symbols (see 10.8.5). Following C-CRC-RA2, the ATU-C shall enter state C-REVERB-RA. + +### 10.8.7 C-REVERB-RA + +C-REVERB-RA is the same as C-REVERB4. If, however, the ATU-C does not detect R-SEGUE-RA within 4000 symbols it shall timeout and reset to C-SILENT1 (see Recommendation G.994.1). After detection of R-CRC4, the ATU-C shall continue to transmit C-REVERB-RA for at least another 80 symbols before moving to state C-SEGUE-RA. + +### 10.8.8 C-SEGUE-RA + +C-SEGUE-RA is the same as C-SEGUE2. Following C-SEGUE-RA the ATU-C shall enter state C-MSG2. + +### 10.8.9 C-MSG2 + +C-MSG2 transmits a 32-bit message signal to the ATU-R. This message includes the total number of bits per symbol supported, the estimated upstream loop attenuation, and the performance margin with the selected rate option. The message, $m$ , is defined by: + +$$m = \{m_{31}, m_{30}, \dots, m_1, m_0\} \quad (10-8)$$ + +with $m_0$ being transmitted first. The message components are defined in the following subclauses, and their assigned positions within the composite message, $m$ , are defined in Table 10-13. + +**Table 10-13/G.992.1 – Assignment of 32 bits of C-MSG2** + +| Suffix(ces) of $m_i$ (Note 1) | Parameter (Note 2) | +|--------------------------------------------------------------------------------------------|----------------------------------------------| +| 31-26 | Estimated average loop attenuation | +| 25-21 | Reserved for future use | +| 20-16 | Performance margin with selected rate option | +| 15-9 | Reserved for future use | +| 8-0 | Total number of bits supported | +| NOTE 1 – Within the separate fields the least significant bits have the lowest subscripts. | | +| NOTE 2 – All reserved bits shall be set to "0". | | + +A total of 4-symbol periods are used to communicate the 32-bit message, with 8 bits transmitted on each symbol. Two bits are encoded onto each of the subcarriers numbered $n_{1C-MSG2}$ through ( $n_{1C-MSG2} + 3$ ) using the 4-QAM constellation labelling given in 7.11.3 (for the synchronization symbol) and 10.4.5 (for C-REVERB1). The same two bits are also encoded in the same way onto a set of backup carriers, namely, subcarriers $n_{2C-MSG2}$ through ( $n_{2C-MSG2} + 3$ ). The least significant byte of the message is transmitted in the first symbol of C-MSG2, with the two least significant bits of each byte encoded onto carriers $n_{1C-MSG2}$ and $n_{2C-MSG2}$ . In addition, the pilot, subcarrier $n_{C-PILOT1}$ , shall be modulated with (+,+). Following C-MSG2, the ATU-C shall enter signalling state C-CRC3. + +$n_{1C-MSG2}$ and $n_{2C-MSG2}$ shall be used as defined in Annexes A, B and C. + +For Annex A, see A.3.8. + +For Annex B, see B.3.9. + +For Annex C, see C.7.9.1. + +#### 10.8.9.1 Estimated average upstream loop attenuation + +During channel analysis the ATU-C receiver estimates the upstream channel gain of each subcarrier in preparation for computing the SNR for each tone; it shall also calculate the average loop attenuation. This attenuation is defined as the difference between the total maximum transmit power (as defined in A.2.4.3.3 for Annexes A and C, and in B.2.2.3.2 for Annex B) and the total received power, rounded to the nearest 0.5 dB. + +For Annexes A and C, see A.3.2. + +For Annex B, see B.3.4. + +The attenuation is encoded into bits 31-26 of C-MSG2 as the integer binary representation of twice the attenuation (e.g. if the average attenuation is 21.5 dB then $\{m_{31}, \dots, m_{26}\} = 101011_2$ ). + +#### 10.8.9.2 Performance margin with selected rate option + +The ATU-C receiver shall select one of the rates options sent from the ATU-C during C-RATES-RA with a satisfactory upstream performance margin. This selected option is encoded in C-RATES2. This margin (rounded to the nearest dB) is encoded into bits 20-16 of C-MSG2 using a conventional binary representation (e.g. if the margin is 9 dB then $\{m_{20}, \dots, m_{16}\} = 01001_2$ ). + +#### 10.8.9.3 Total number of bits per symbol supported + +The ATU-C receiver shall also calculate the maximum number of bits per symbol that the upstream channel can support with the performance margin defined in C-MSG-RA at an error rate of $10^{-7}$ . This number is encoded into bits 8-0 using a conventional binary representation [e.g. if the + +maximum number of bits that can be supported is 127 (data rate = 508 kbit/s), $\{m_8, \dots, m_0\} = 001111111_2$ ]. + +### 10.8.10 C-CRC3 + +C-CRC3 is a cyclic redundancy check for detection of errors in the reception of C-MSG2 at the ATU-R. The CRC polynomial $c(D)$ and generator polynomial $g(D)$ are the same as for C-CRC1, as defined in 10.6.3. These 16 bits shall be transmitted in 2-symbol periods using the method described in 10.8.9. Following C-CRC3, the ATU-C shall enter state C-RATES2. + +### 10.8.11 C-RATES2 + +C-RATES2 is the reply to R-RATES-RA. It combines the selected downstream option with the selected upstream option. It thus transmits the final decision on the rates that will be used in both directions. + +The ATU-C shall not change the downstream option from that selected in R-RATES2. + +The length of C-RATES2 is 8 bits, and the bit pattern for C-RATES2 is shown in Table 10-14. Other bit patterns that are not specified in the table are reserved for future use. If none of the options requested during C-RATES1 or C-RATES-RA can be implemented, ATU-C then returns to C-SILENT1 (see Recommendation G.994.1) for retraining. One symbol period is used to transmit these 8 bits using the method described in 10.8.9. Following C-RATES2, the ATU-C shall enter signalling state C-CRC4. + +**Table 10-14/G.992.1 – Bit pattern for C-RATES2** + +| (Downstream, upstream) | Bit pattern for C-RATES2 (MSB first) (Note) | +|-------------------------------------------------------------------------------|---------------------------------------------| +| (option 1, option 1) | 00010001 2 | +| (option 1, option 2) | 00010010 2 | +| (option 1, option 3) | 00010100 2 | +| (option 1, option 4) | 00011000 2 | +| (option 2, option 1) | 00100001 2 | +| (option 2, option 2) | 00100010 2 | +| (option 2, option 3) | 00100100 2 | +| (option 2, option 4) | 00101000 2 | +| (option 3, option 1) | 01000001 2 | +| (option 3, option 2) | 01000010 2 | +| (option 3, option 3) | 01000100 2 | +| (option 3, option 4) | 01001000 2 | +| (option 4, option 1) | 10000001 2 | +| (option 4, option 2) | 10000010 2 | +| (option 4, option 3) | 10000100 2 | +| (option 4, option 4) | 10001000 2 | +| All options fail | 00000000 2 | +| NOTE – All other bit patterns that are not shown are reserved for future use. | | + +### 10.8.12 C-CRC4 + +C-CRC4 is a cyclic redundancy check for detection of errors in the reception of C-RATES2 at the ATU-R. Its relation to C-RATES2 is the same as that of C-CRC3 to C-MSG2. Its 16 bits shall be transmitted in 2 symbols (see 10.8.11). Following C-CRC4, the ATU-C shall enter state C-B&G. + +### 10.8.13 C-B&G + +For Annex B, see B.3.12. + +For Annex C, see C.7.9.2. + +C-B&G shall be used to transmit to the ATU-R the bits and gains information, $\{b_1, g_1, b_2, g_2, \dots, b_{31}, g_{31}\}$ , that are to be used on the upstream carriers. $b_i$ indicates the number of bits to be coded by the ATU-R transmitter onto the $i$ th upstream carrier; $g_i$ indicates the scale factor, relative to the gain that was used for that carrier during the transmission of R-MEDLEY, that shall be applied to the $i$ th upstream carrier. Because no bits or energy will be transmitted at DC or one-half the sampling rate, $b_0, g_0, b_{32}$ , and $g_{32}$ are all presumed to be zero and shall not be transmitted. + +Each $b_i$ shall be represented as an unsigned 4-bit integer, with valid $b_i$ s lying in the range of zero to $N_{\text{upmax}}$ , the maximum number of bits that the ATU-R is prepared to modulate onto any subcarrier, which is communicated in R-MSG1. + +Each $g_i$ shall be represented as an unsigned 12-bit fixed-point quantity, with the binary point assumed just to the right of the third most significant bit. For example, a $g_i$ with binary representation (most significant bit listed first) $001.010000000_2$ would instruct the ATU-R to scale the constellation for carrier $i$ , by a gain factor of 1.25, so that the power in that carrier shall be 1.94 dB higher than it was during R-MEDLEY. + +For subcarriers on which no data are to be transmitted, and the receiver will never allocate bits (e.g. out-of-band subcarriers) both $b_i$ and $g_i$ shall be set to zero ( $0000_2$ and $000000000000_2$ , respectively). For subcarriers on which no data are to be currently transmitted, but the receiver may allocate bits later (e.g. as a result of an SNR improvement), the $b_i$ shall be set to zero and the $g_i$ to a value in the 0.19 to 1.33 range ( $000.001100000_2$ to $001.010101011_2$ ). + +The C-B&G information shall be mapped in a 496-bit (62 byte) message $m$ defined by: + +$$m = \{m_{495}, m_{494}, \dots, m_1, m_0\} = \{g_{31}, b_{31}, \dots, g_1, b_1\}, \quad (10-9)$$ + +with the MSB of $b_i$ and $g_i$ in the higher $m$ index and $m_0$ being transmitted first. The message $m$ shall be transmitted in 62 symbols, using the transmission method as described in 10.8.9. + +Following C-B&G, the ATU-C shall enter the state C-CRC5. + +### 10.8.14 C-CRC5 + +C-CRC5 is a cyclic redundancy check for detection of errors in the reception of C-B&G at the ATU-R. Its relation to C-B&G is the same as that of C-CRC3 to C-MSG2. Its 16 bits shall be transmitted in 2 symbols (see 10.8.9). Following C-CRC5, the ATU-C shall enter state C-REVERB5. + +### 10.8.15 C-REVERB5 + +C-REVERB5 is the same as C-REVERB4 (see 10.8.1). The only difference is the maximum duration of 4000 symbols. The duration of C-REVERB5 depends upon the state of the ATU-R and the internal processing of the ATU-C. The ATU-C shall transmit C-REVERB5 until it has received, checked the reliability of, and established in the ATU-C transmitter, the downstream bits and gains information contained in R-B&G. If bits and gains information is not received, checked and + +established within 4000 symbols, the ATU-C shall timeout and reset to C-SILENT1 (see Recommendation G.994.1). The ATU-C shall enter state C-SEGUE3 as soon as it is prepared to transmit according to the conditions specified in R-B&G. + +### 10.8.16 C-SEGUE3 + +C-SEGUE3 is used to notify the ATU-R that the ATU-C is about to enter the steady-state signalling state C-SHOWTIME. The signal C-SEGUE3 is the same as C-SEGUE2 (see 10.8.2). The duration of C-SEGUE3 is 10 symbol periods. Following C-SEGUE3 the ATU-C has completed initialization and shall enter state C-SHOWTIME. + +## 10.9 Exchange – ATU-R + +During exchange there are two cases when the ATU-R shall reset itself: timeouts and error detection by a CRC checksum. Both shall trigger a reset to R-SILENT0 (see Recommendation G.994.1). The exchange procedure is partly synchronized between ATU-C and ATU-R, and partly interactive. During the interactive parts (R-REVERB-RA, R-REVERB5 and R-REVERB6) a timeout shall occur when the time in either state exceeds 4000 symbols. + +### 10.9.1 R-SEGUE3 + +The signal R-SEGUE3 is the same as R-SEGUE2 (see 10.7.3). The duration of R-SEGUE3 is 10 symbol periods. Following R-SEGUE3 the ATU-R shall enter state R-MSG-RA to begin a second exchange of rates. + +### 10.9.2 R-MSG-RA + +R-MSG-RA is similar to R-MSG2, but expanded by 80 bits. The bit assignments are as shown in Table 10-15. + +**Table 10-15/G.992.1 – Assignment of 80 bits of R-MSG-RA** + +| Suffix(ces) of $m_i$ (Note 1) | Parameter (Note 2) | +|-------------------------------|------------------------------------------------| +| 79-56 | Reserved for future use | +| 55-49 | Number of RS overhead bytes, (R) | +| 48-40 | Number of RS payload bytes, (K) | +| 39-32 | Number of tones carrying data (ncloaded) | +| 31-25 | Estimated average loop attenuation | +| 24-21 | Coding gain | +| 20-16 | Performance margin with selected rate option | +| 15-14 | Reserved for future use | +| 13-12 | Maximum Interleave Depth | +| 11-0 | Total number of bits per DMT symbol, $B_{max}$ | + +NOTE 1 – Within the separate fields the least significant bits have the lowest subscripts. +NOTE 2 – All reserved bits shall be set to "0". + +For Annex C, see C.7.10.1. + +#### 10.9.2.1 Number or RS overhead bytes (R) + +This is the R ( $R_I$ or $R_F$ , as defined in 7.4.1.2) parameter used to calculate $B_{max}$ . + +This parameter shall be calculated assuming single latency operation with $S \leq 1$ . + +#### 10.9.2.2 Number of RS payload bytes (K) + +This is the K ( $K_I$ or $K_F$ , as defined in 7.4.1.2) parameter used to calculate $B_{max}$ . + +This parameter shall be calculated assuming single latency operation with $S \leq 1$ . + +#### 10.9.2.3 Number of tones carrying data (ncloaded) + +This is the number of subcarriers with $b_i > 0$ used to calculate $B_{max}$ . + +#### 10.9.2.4 Estimated average loop attenuation + +This parameter shall be defined as in R-MSG2, see 10.9.8. + +#### 10.9.2.5 Coding gain + +The coding gain of RS FEC and trellis coding as used to calculate $B_{max}$ . + +The coding gain is expressed in steps of 0.5 dB in the 0 to 7.5 dB range. + +#### 10.9.2.6 Performance margin with selected rate option + +This parameter shall be defined as in R-MSG2, see 10.9.8. If R-RATES-RA indicates "no option selected", then this parameter shall be set to "0" or reflect the performance margin in dB corresponding to $B_{max}$ (which may be 0 to 3 dB above the minimum requested SNR margin). + +#### 10.9.2.7 Maximum Interleaving Depth + +This parameter shall reflect the maximum interleaving depth supported by the ATU-R receiver as defined in Table 10-16. + +**Table 10-16/G.992.1 – Bit settings for Maximum Interleaving Depth** + +| Bit 13 | Bit 12 | $D_{max}$ | +|--------|--------|----------------| +| 0 | 0 | 64 (mandatory) | +| 0 | 1 | 128 (optional) | +| 1 | 0 | 256 (optional) | +| 1 | 1 | 512 (optional) | + +#### 10.9.2.8 Total number of bits supported ( $B_{max}$ ) + +This parameter shall be defined as in R-MSG2, see 10.9.8. If both ATU-C and ATU-R support trellis coding, then trellis coding shall be assumed when calculating $B_{max}$ . + +The following relationship exists between $B_{max}$ , ncloaded, K and R: + +$$\text{With trellis coding } B_{max} = 8 \times (K + R/S) + \text{roundup}(\text{ncloaded}/2) + 4 = \sum b_i$$ + +$$\text{Without trellis coding } B_{max} = 8 \times (K + R/S) = \sum b_i$$ + +For Annex C, see C.7.10.1.1. + +### 10.9.3 R-CRC-RA1 + +R-CRC-RA1 is a cyclic redundancy check for detection of errors in the reception of R-MSG-RA. Its relation to R-MSG-RA is the same as that of R-CRC3 to R-MSG2. Following R-CRC-RA1, the ATU-R shall enter state R-RATES-RA. + +#### 10.9.4 R-RATES-RA + +R-RATES-RA is the reply to C-RATES1 based on the results of the downstream channel analysis and is similar to R-RATES2. Instead of listing the $B_F$ , $B_I$ as in C-RATES1, the ATU-R does one of the following: + +- sends back only the option number of the highest data rate that can be supported based on the measured SNR of the downstream channel (not taking into account impulse noise resilience); +- indicates that no option selection was made at this time, but will be made later based on C-RATES-RA information; +- indicates none of the options requested during C-RATES1 can be implemented. + +As in R-RATES2, 4 bits are used for the option number. A total of 8 bits are used for R-RATES-RA, and the bit patterns are shown in Table 10-17. Other bit patterns that are not specified in the table are reserved for future use. One symbol period is used to transmit these 8 bits using the method described in 10.9.8. Following R-RATES-RA, the ATU-R shall enter state R-CRC-RA2. + +The format of R-RATES-RA is the same as R-RATES2, except for the additional bit pattern used to indicate "no option selected". + +**Table 10-17/G.992.1 – Bit pattern for R-RATES-RA** + +| Downstream | Bit pattern for R-RATES-RA (MSB first) | +|-------------------------------------------------------------------------------|----------------------------------------| +| Option 1 | 00010001 2 | +| Option 2 | 00100010 2 | +| Option 3 | 01000100 2 | +| Option 4 | 10001000 2 | +| No option selected | 00000001 2 | +| All options fail | 00000000 2 | +| NOTE – All other bit patterns that are not shown are reserved for future use. | | + +#### 10.9.5 R-CRC-RA2 + +R-CRC-RA2 is a cyclic redundancy check for detection of errors in the reception of R-RATES-RA. Its relation to R-RATES-RA is the same as that of R-CRC3 to R-MSG2. Following R-CRC-RA2, the ATU-R shall enter state R-REVERB-RA. + +#### 10.9.6 R-REVERB-RA + +R-REVERB-RA is the same as R-REVERB3 (see 10.7.2). The duration of R-REVERB-RA depends upon the signalling state of the ATU-C and the internal processing of the ATU-R, but has a maximum of 4000 symbols. The ATU-R shall transmit R-REVERB-RA until it has received and checked the reliability of the upstream bits and gains information contained in C-RATES-RA. After the ATU-R has received C-CRC-RA2, it shall continue to transmit R-REVERB-RA for another 64 symbols. It shall then enter R-SEGUE-RA. + +If it has not successfully detected all the control signals within 4000 symbols, it shall timeout and reset to R-SILENT0 (see Recommendation G.994.1). + +#### 10.9.7 R-SEGUE-RA + +R-SEGUE-RA is the same as R-SEGUE4. Following R-SEGUE-RA, the ATU-R shall enter state R-MSG2. + +### 10.9.8 R-MSG2 + +R-MSG2 transmits a 32-bit message signal to the ATU-C. This message includes the total number of bits per symbol supported, the estimated downstream loop attenuation, and the performance margin with the selected rate option. The message, $m$ , is defined by: + +$$m = \{m_{31}, m_{30}, \dots, m_1, m_0\} \quad (10-10)$$ + +with $m_0$ being transmitted first. The message components are defined in the following subclauses, and their assigned positions within the composite message, $m$ , are defined in Table 10-18. + +**Table 10-18/G.992.1 – Assignment of 32 bits of R-MSG2** + +| Suffix(ces) of $m_i$ (Note 1) | Parameter (Note 2) | +|-------------------------------|----------------------------------------------| +| 31-25 | Estimated average loop attenuation | +| 24-21 | Reserved for future use | +| 20-16 | Performance margin with selected rate option | +| 15-12 | Reserved for future use | +| 11-0 | Total number of bits supported | + +NOTE 1 – Within the separate fields the least significant bits have the lowest subscripts. +NOTE 2 – All reserved bits shall be set to "0". + +A total of 4 symbol periods are used to communicate the 32-bit message, with 8 bits transmitted on each symbol. Two bits are encoded onto each of the subcarriers numbered $n_{1R-MSG2}$ through ( $n_{1R-MSG2} + 3$ ) using the 4-QAM constellation labelling given in 8.11.3 (for the synchronization symbol) and 10.4.5 (for C-REVERB1). The same two bits are also encoded in the same way onto a set of backup carriers, namely, subcarriers $n_{2R-MSG2}$ through ( $n_{2R-MSG2} + 3$ ). The least significant byte of the message is transmitted in the first symbol of R-MSG2, with the two least significant bits of each byte encoded onto carriers $n_{1R-MSG2}$ and $n_{2R-MSG2}$ . Following R-MSG2, the ATU-R shall enter state R-CRC3. + +$n_{1R-MSG2}$ and $n_{2R-MSG2}$ shall be used as defined in Annexes A, B and C. + +For Annex A, see A.3.9. + +For Annex B, see B.3.10. + +For Annex C, see C.7.10.2. + +#### 10.9.8.1 Estimated average downstream loop attenuation + +During channel analysis the ATU-R receiver estimates the downstream channel gain of each subcarrier in preparation for computing the SNR for each tone; it shall also calculate the average loop attenuation. This attenuation is defined as the difference between ATU-C maximum total transmit power (as defined in A.1.2.3.3 for Annexes A and C, and B.1.3.2.2 for Annex B, taking into account power cut-back) and the total received power, rounded to the nearest 0.5 dB. + +For Annexes A and C, see A.3.3. + +For Annex B, see B.3.5. + +The attenuation is encoded into bits 31-25 of R-MSG2 as the integer binary representation of twice the attenuation [e.g. if the average attenuation is 21.5 dB then $\{m_{31}, \dots, m_{25}\} = 0101011_2$ ]. + +### 10.9.8.2 Performance margin with selected rate option + +The ATU-R receiver shall select one of the rates options sent from the ATU-C during C-RATES1 or C-RATES-RA with a satisfactory downstream margin. This selected option is encoded in R-RATES2. This margin (rounded to the nearest dB) is encoded into bits 20-16 of R-MSG2 using a conventional binary representation [e.g. if the margin is 9 dB then $\{m_{20}, \dots, m_{16}\} = 01001_2$ ]. + +### 10.9.8.3 Total number of bits per symbol supported + +The ATU-R receiver shall also calculate the maximum number of bits per symbol that the downstream channel can support with the performance margin defined in C-MSG1 or C-MSG-RA at an error rate of $10^{-7}$ . This number is encoded into bits 11-0 using a conventional binary representation [e.g. if the maximum number of bits that can be supported is 1724 (data rate = 6896 kbit/s), $\{m_{11}, \dots, m_0\} = 11010111100_2$ ]. + +For Annex C, see C.7.10.2.1. + +## 10.9.9 R-CRC3 + +R-CRC3 is a cyclic redundancy check for detection of errors in the reception of R-MSG2 at the ATU-C. The CRC polynomial $c(D)$ and generator polynomial $g(D)$ are as described in 10.6.3. These bits are transmitted in 2 symbol periods using the method described in 10.9.8. Following R-CRC3, the ATU-R shall enter state R-RATES2. + +## 10.9.10 R-RATES2 + +R-RATES2 is the reply to C-RATES-RA based on the results of the downstream channel analysis. Instead of listing the $B_F$ , $B_I$ as in C-RATES1, the ATU-R sends back only the option number of the selected data rate that can be supported based on the measured SNR of the downstream channel (not taking into account impulse noise resilience). As in C-RATES2, 4 bits are used for the option number. A total of 8 bits are used for R-RATES2, and the bit patterns are shown in Table 10-19. Other bit patterns that are not specified in the table are reserved for future use. If none of the options requested during C-RATES1 can be implemented, ATU-R then returns to R-SILENT0 (see Recommendation G.994.1) for retraining. One symbol period is used to transmit these 8 bits using the method described in 10.9.8. Following R-RATES2, the ATU-R shall enter state R-CRC4. + +**Table 10-19/G.992.1 – Bit pattern for R-RATES2** + +| Downstream | Bit pattern for R-RATES2 (MSB first) | +|-------------------------------------------------------------------------------|--------------------------------------| +| Option 1 | 00010001 2 | +| Option 2 | 00100010 2 | +| Option 3 | 01000100 2 | +| Option 4 | 10001000 2 | +| All options fail | 00000000 2 | +| NOTE – All other bit patterns that are not shown are reserved for future use. | | + +If it is determined that none of the four options can be implemented with the connection, the ATU-R shall return to R-SILENT0 (see Recommendation G.994.1) for retraining. + +## 10.9.11 R-CRC4 + +R-CRC4 is a cyclic redundancy check for detection of errors in the reception of R-RATES2 at the ATU-C. Its relation to R-RATES2 is the same as that of R-CRC3 to R-MSG2. Following R-CRC4, the ATU-R shall enter state R-REVERB5. + +### 10.9.12 R-REVERB5 + +R-REVERB5 is the same as R-REVERB3 (see 10.7.2). The duration of R-REVERB5 depends upon the signalling state of the ATU-C and the internal processing of the ATU-R, but has a maximum of 4000 symbols. The ATU-R shall transmit R-REVERB5 until it has received and checked the reliability of the upstream bits and gains information contained in C-B&G. After the ATU-R has received C-CRC5, it shall continue to transmit R-REVERB5 for another 64 symbols. It shall then enter R-SEGUE4. If it has not successfully detected all the control signals within 4000 symbols, it shall timeout and reset to R-SILENT0 (see Recommendation G.994.1). + +### 10.9.13 R-SEGUE4 + +The purpose of R-SEGUE4 is to notify the ATU-C that the ATU-R is about to enter R-B&G. R-SEGUE4 is the same as R-SEGUE3 (see 10.9.1). The duration of R-SEGUE4 is 10 symbol periods. Following R-SEGUE4, the ATU-R shall enter state R-B&G. + +### 10.9.14 R-B&G + +The purpose of R-B&G is to transmit to the ATU-C the bits and gains information, $\{b_1, g_1, b_2, g_2, \dots, b_{255}, g_{255}\}$ , to be used on the downstream subcarriers. $b_i$ indicates the number of bits to be coded by the ATU-C transmitter onto the $i$ th downstream subcarrier; $g_i$ indicates the scale factor that shall be applied to the $i$ th downstream subcarrier, relative to the gain that was used for that carrier during the transmission of C-MEDLEY. Because no bits or energy will be transmitted at DC or one-half the sampling rate, $b_0, g_0, b_{256}$ , and $g_{256}$ are all presumed to be zero, and are not transmitted. Because subcarrier $N_{\text{pilot}}$ is reserved as the pilot tone, $b(N_{\text{pilot}})$ shall be set to 0 and $g(N_{\text{pilot}})$ shall be set to $g_{\text{sync}}$ . $N_{\text{pilot}}$ and $g_{\text{sync}}$ are defined in Annexes A, B and C. The value $g_{\text{sync}}$ represents the gain scaling applied to the sync symbol. + +Each $b_i$ is represented as an unsigned 4-bit integer, with valid $b_i$ lying in the range of zero to $N_{\text{downmax}}$ , the maximum number of bits that the ATU-C is prepared to modulate onto any subcarrier, which is communicated in C-MSG1. + +Each $g_i$ is represented as an unsigned 12-bit fixed-point quantity, with the binary point assumed just to the right of the third most significant bit. For example, a $g_i$ with binary representation (most significant bit listed first) $001.010000000_2$ would instruct the ATU-C to scale the constellation for carrier $i$ by a gain factor of 1.25, so that the power in that carrier shall be 1.94 dB higher than it was during C-MEDLEY. + +For subcarriers on which no data are to be transmitted, and the receiver will never allocate bits (e.g. out-of-band subcarriers) both $b_i$ and $g_i$ shall be set to zero ( $0000_2$ and $00000000\ 0000_2$ , respectively). For subcarriers on which no data are to be currently transmitted, but the receiver may allocate bits later (e.g. as a result of an SNR improvement), the $b_i$ shall be set to zero and the $g_i$ to a value in the 0.19 to 1.33 range ( $000.001100000_2$ to $001.010101011_2$ ). + +The R-B&G information shall be mapped in a 4080-bit (510 byte) message $m$ defined by: + +$$m = \{m_{4079}, m_{4078}, \dots, m_1, m_0\} = \{g_{255}, b_{255}, \dots, g_1, b_1\}, \quad (10-11)$$ + +with the MSB of $b_i$ and $g_i$ in the higher $m$ index and $m_0$ being transmitted first. The message $m$ shall be transmitted in 510 symbols, using the transmission method as described in 10.9.8. + +Following R-B&G, the ATU-C shall enter the state R-CRC5. + +#### **10.9.15 R-CRC5** + +R-CRC5 is a cyclic redundancy check for detection of errors in the reception of R-B&G at the ATU-C. Its relation to R-B&G is the same as that of R-CRC3 to R-MSG2. Following R-CRC5, the ATU-R shall enter state R-REVERB6. + +#### **10.9.16 R-REVERB6** + +R-REVERB6 is the same as R-REVERB3 (see 10.7.2). The duration of R-REVERB6 depends upon the signalling state of the ATU-C and the internal processing of the ATU-R, but has a maximum of 4000 symbols. The ATU-R shall transmit R-REVERB6 until it has detected all ten symbols of C-SEGUE3; it shall then enter R-SEGUE5. If it has not successfully detected C-SEGUE3 within 4000 symbols, it shall timeout and reset to R-SILENT0 (see Recommendation G.994.1). + +#### **10.9.17 R-SEGUE5** + +The purpose of R-SEGUE5 is to notify the ATU-C that the ATU-R is about to enter the steady-state signalling state R-SHOWTIME. R-SEGUE5 is identical to R-SEGUE3 (see 10.9.1). The duration of R-SEGUE5 is 10 symbol periods. Following R-SEGUE5, the ATU-R has completed initialization and shall enter state R-SHOWTIME. + +#### **10.9.18 Details of Initialization timing** + +The requirements for the initialization sequence (as defined in 10.1 through 10.9) are shown in Figures 10-5 and 10-6. Figure 10-5 shows the first part of the initialization sequence, up to C-MEDLEY and R-MEDLEY. Figure 10-6 shows the rest of the initialization sequence. + +![](f431b5db0c635c95318cff1adbe10c05_img.jpg) + +| | C-GALF2
(G.994.1) | C-FLAG2
(G.994.1) | | | R-GALF2
(G.994.1) | R-FLAG2
(G.994.1) | | +|---------------------------|----------------------------------------------|------------------------|--------------------------|----------------------------------------------------|----------------------------------|----------------------|----------------------------| +| $\geq 128$
$\leq 2048$ | C-QUIET2 | | | | R-QUIET2 | | $\leq 8000$ | +| | If R-ACK2 | If R-ACK1
C-PILOT1A | $\geq 128$ | | | | | +| | C-PILOT1 | C-QUIET3A | $\leq 16$ | | | | | +| | | | $\geq 496$
$\leq 512$ | | | | | +| | | | | $\geq 512$
$\leq 516$ | | | | +| 512 | C-REVERB1 | | | | R-REVERB1 | | 4096 | +| 3072 | C-PILOT2 | | | | | | | +| 512 | C-ECT | | | | | | | +| 1536 | C-REVERB2 | | | | R-QUIET3 | | $\geq 2047$
$\leq 2048$ | +| 512 | R-ACK2 then C-PILOT3
R-ACK1 then C-QUIET5 | | | Last symbol
may be
shortened by
n samples | R-ECT | | 512 | +| 1024 | C-REVERB3 | | | | R-REVERB2 | | $\geq 1024$
$\leq 1056$ | +| 10 | C-SEGUE1 | | | Introduction of
cyclic prefix | R-SEGUE1 | | 10 | +| 1072 | C-RATES1/C-CRC1
C-MSG1/C-CRC2 | | | | R-REVERB3 | | $\geq 1092$
$\leq 4000$ | +| | | | $\geq 20$
$\leq 2928$ | | | | | +| 16 384 | C-MEDLEY | | | | R-SEGUE2 | | 10 | +| | | | | | R-RATES1/R-CRC1
R-MSG1/R-CRC2 | | 464 | +| | | | | | R-MEDLEY | | 16 384 | + +T1532650-99 + +Figure 10-5/G.992.1 – Timing diagram of the initialization sequence – Part 1 + +![Timing diagram of the initialization sequence - Part 2. The diagram shows a sequence of messages between a client (C) and a server (R). The sequence starts with C-REVERB4, followed by C-SEGUE2, C-RATES-RA/C-CRC-RA1, C-MSG-RA/C-CRC-RA2, C-REVERB-RA, C-SEGUE-RA, C-MSG2/C-CRC3, C-RATES2/C-CRC4, C-B&G/C-CRC5, C-REVERB5, C-SEGUE3, and finally SHOWTIME. The server responds with R-MEDLEY, R-REVERB4, R-SEGUE3, R-MSG-RA/R-CRC-RA1, R-RATES-RA/R-CRC-RA2, R-REVERB-RA, R-SEGUE-RA, R-MSG2/R-CRC-3, R-RATES2/R-CRC4, R-REVERB5, R-SEGUE4, R-B&G/R-CRC5, R-REVERB6, R-SEGUE5, and SHOWTIME. Timing constraints are indicated by arrows and numerical values.](4ef412e08808c40e0beb7808d36b9379_img.jpg) + +| | | | | | +|---------------------------|--------------------------------------------|------------------------------------------------|--------------------------------------------|---------------------------| +| $\geq 727$
$\leq 6000$ | C-REVERB4 | | R-MEDLEY | | +| | | | R-REVERB4 | 128 | +| | | | R-SEGUE3 | 10 | +| | | | R-MSG-RA/R-CRC-RA1
R-RATES-RA/R-CRC-RA2 | 15 | +| | | $\geq 80$
$\leq 2413$ | | | +| 10 | C-SEGUE2 | | R-REVERB-RA | $\geq 288$
$\leq 4000$ | +| 130 | C-RATES-RA/C-CRC-RA1
C-MSG-RA/C-CRC-RA2 | | | | +| | | $\geq 64$
$\leq 1447$ | | | +| $\geq 163$
$\leq 4000$ | C-REVERB-RA | | R-SEGUE-RA | 10 | +| | | | R-MSG2/R-CRC-3
R-RATES2/R-CRC4 | 9 | +| | | $\geq 80$
$\leq 2534$ | | | +| 10 | C-SEGUE-RA | | R-REVERB5 | $\geq 227$
$\leq 4000$ | +| 9 | C-MSG2/C-CRC3
C-RATES2/C-CRC4 | | | | +| 64 | C-B&G/C-CRC5 | | | | +| | | $\geq 64$
$\leq 1383$ | | | +| $\geq 586$
$\leq 4000$ | C-REVERB5 | | R-SEGUE4 | 10 | +| | | | R-B&G/R-CRC5 | 512 | +| | | $\leq 2095$ | | | +| 10 | C-SEGUE3 | | R-REVERB6 | $\leq 4000$ | +| | | $\leq 1895$ | | | +| | SHOWTIME | | R-SEGUE5 | 10 | +| | | Maximum
initialization time
11.3 seconds | SHOWTIME | | + +Timing diagram of the initialization sequence - Part 2. The diagram shows a sequence of messages between a client (C) and a server (R). The sequence starts with C-REVERB4, followed by C-SEGUE2, C-RATES-RA/C-CRC-RA1, C-MSG-RA/C-CRC-RA2, C-REVERB-RA, C-SEGUE-RA, C-MSG2/C-CRC3, C-RATES2/C-CRC4, C-B&G/C-CRC5, C-REVERB5, C-SEGUE3, and finally SHOWTIME. The server responds with R-MEDLEY, R-REVERB4, R-SEGUE3, R-MSG-RA/R-CRC-RA1, R-RATES-RA/R-CRC-RA2, R-REVERB-RA, R-SEGUE-RA, R-MSG2/R-CRC-3, R-RATES2/R-CRC4, R-REVERB5, R-SEGUE4, R-B&G/R-CRC5, R-REVERB6, R-SEGUE5, and SHOWTIME. Timing constraints are indicated by arrows and numerical values. + +Figure 10-6/G.992.1 – Timing diagram of the initialization sequence – Part 2 + +## 11 AOC on-line adaptation and reconfiguration + +### 11.1 The ADSL overhead control (AOC) channel + +The AOC data are carried as overhead bytes in the ADSL framing structure. The actual multiplexing of these overhead bytes into the ADSL framing structure depends on the framing structure used (i.e. full overhead or reduced overhead) and on the allocation of any bearer channel to the fast or interleaved data buffer (see 7.4). + +#### 11.1.1 AOC message header + +The type and length of an AOC message (except for the acknowledge messages) are identified by a byte-length header. In particular, the AOC channel sends the all binary zeros "000000002" AOC stuffing pattern in the Idle State, and a valid AOC message always begins with a non-zero byte. Table 11-1 summarizes the current valid AOC message headers. For example, in the case of a bit swap, the AOC header "111111112" will be detected, and the next byte of AOC data shall determine whether the message is a bit swap request or a bit swap acknowledge (see 11.2.5). In the case when a function is requested but cannot be performed by either the ATU-C or the ATU-R for any reason (e.g. because the requested $b_i$ value exceeds the maximum number of bits per tone supported), an unable to comply message ("111100002") is issued. Future AOC headers can be added when new AOC messages/functions are identified. Also, a block of AOC header values ("1100xxxx2") is set aside for vendor specific AOC messages. + +**Table 11-1/G.992.1 – AOC message headers** + +| Header | Message length (bytes) | Interpretation | +|-----------------------|------------------------|-----------------------------------| +| 00001111 2 | Undefined | Reconfiguration message | +| 1100xxxx 2 | Undefined | Vendor specific message | +| 11110000 2 | 1 | Unable to comply message (Note) | +| 11111100 2 | 13 | Extended bit swap request message | +| 11111111 2 | 9 | Bit swap request message | +| 11111111 2 | 3 | Bit swap acknowledge message | + +NOTE – The "unable to comply" message shall consist of a single byte: the header byte. + +The header bytes values are given in binary format (MSB left, LSB right) and represent aoc7-aoc0 bits (MSB in bit 7, LSB in bit 0) as carried in the overhead (see 7.4.1.2 and 8.4.1.2). All other bytes in the AOC message shall be mapped according to the same convention. + +#### 11.1.2 AOC protocol + +All AOC messages shall be transmitted 5 consecutive times (i.e. 5 concatenated and identical messages without AOC stuffing patterns in between) for extra security. At least 20 AOC stuffing patterns shall be inserted between two consecutive groups of five concatenated and identical messages. + +An ATU-x receiving an AOC message shall act on that AOC message only if it has received three identical messages in a time period spanning 5 of that particular message. When an ATU-x receives an unrecognizable command, it shall take no action. + +## 11.2 On-line adaptation – Bit swapping + +Bit swapping enables an ADSL system to change the number of bits assigned to a subcarrier, or change the transmit energy of a subcarrier without interrupting data flow. + +Either ATU-x may initiate a bit swap; the swapping procedures in the upstream and downstream channels are independent, and may take place simultaneously. + +For the bit swap protocol, the "receiver" is the ATU-x that is receiving the data; it transmits a bit swap (extended or simple) request message and receives the bit swap acknowledge message. The "transmitter" is the ATU-x that is transmitting the data; it receives a bit swap request (extended or simple) message and shall transmit the bit swap acknowledge message. + +There shall be a maximum of one downstream bit swap request outstanding at any time. There shall be a maximum of one upstream bit swap request outstanding at any time. + +### 11.2.1 Bit swap channel + +The bit swap process uses the AOC channel, described in 11.1. All bit swap messages shall be repeated five consecutive times over this channel. + +### 11.2.2 Superframe counting + +The transceivers coordinate the bit swaps as follows: + +- The ATU-C and ATU-R transmitters shall start their counters immediately after transmitting C-SEGUE3 and R-SEGUE5 (see 10.8.16 and 10.9.17), respectively; this marks the transition between initialization and steady state operation. +- Superframe counting starts with the first superframe at beginning of Showtime being superframe 0. +- Each transmitter shall increment its counter after sending each ADSL superframe (see 7.4.1.1). +- Correspondingly, each receiver shall start its counter immediately after receiving C-SEGUE3 or R-SEGUE5, respectively, and then increment it after receiving each superframe. +- Superframe counting is performed MOD 256. + +Synchronization of the corresponding transmitter and receiver superframe counters is maintained using the synchronization symbol in the ADSL frame structure. Any form of restart that requires a transition from initialization to steady state shall reset the superframe counter. + +### 11.2.3 Bit swap request + +The receiver shall initiate a bit swap by sending a bit swap request to the transmitter via the AOC channel. This request tells the transmitter which subcarriers are to be modified. + +The format of the request is shown in Table 11-2. + +**Table 11-2/G.992.1 – Format of the bit swap request message** + +| Message header | Message fields 1-4 | | +|--------------------------------------|---------------------|------------------------------| +| {11111111 2 }
(8 bits) | Command
(8 bits) | Subchannel index
(8 bits) | + +The request shall comprise nine bytes as follows: + +- an AOC message header consisting of 8 binary ones; +- message fields 1-4, each of which consists of an eight-bit command followed by a related eight-bit subchannel index. Valid eight-bit commands for the bit swap message shall be as shown in Table 11-3. The eight-bit subchannel index is counted from low to high frequencies with the lowest frequency subcarrier having the number zero. Subcarrier 0 shall not be used. + +**Table 11-3/G.992.1 – Bit swap request commands** + +| Value | Interpretation | +|-----------------------|----------------------------------------------| +| 00000000 2 | Do nothing | +| 00000001 2 | Increase the number of allocated bits by one | +| 00000010 2 | Decrease the number of allocated bits by one | +| 00000011 2 | Increase the transmitted power by 1 dB | +| 00000100 2 | Increase the transmitted power by 2 dB | +| 00000101 2 | Increase the transmitted power by 3 dB | +| 00000110 2 | Reduce the transmitted power by 1 dB | +| 00000111 2 | Reduce the transmitted power by 2 dB | +| 00001xxx 2 | Reserved for vendor discretionary commands | + +The bit swap request message (i.e. header and message fields) shall be transmitted five consecutive times. + +To avoid $g_i$ divergence between ATU-C and ATU-R after several bit swaps, for a $g_i$ update of $\Delta$ dB the new $g_i$ value should be given by: + +$$g_i' = (1/512) \times \text{round}(512 \times g_i \times 10^{\exp(\Delta/20)}) \quad (11-1)$$ + +#### 11.2.4 Extended bit swap request + +Any on-line adaptation may be encoded in an extended bit swap request. However, because a single-bit subcarrier is not allowed, an extended bit swap request containing 6 fields shall be used when decreasing the number of bits on a subcarrier from 2 to 0, or when increasing the number of bits on a subcarrier from 0 to 2. The format of this extended bit swap request is similar to that of the bit swap request (11.2.3), but the number of message fields is increased to 6, and a different message header is used. The format of the request is shown in Table 11-4. + +**Table 11-4/G.992.1 – Format of the extended bit swap request message** + +| Message header | Message fields 1-6 | | +|--------------------------------------|---------------------|------------------------------| +| {11111100 2 }
(8 bits) | Command
(8 bits) | Subchannel index
(8 bits) | + +The receiver shall initiate an extended bit swap by sending an extended bit swap request message to the transmitter. This request tells the transmitter which subcarriers are to be modified. The extended bit swap request message shall comprise 13 bytes as follows: + +- An eight-bit extended bit swap request message header of {111111002}. +- Message fields 1 to 6, each of which is defined as in 11.2.3. + +The receiver shall use two identical message fields to request a 0 to 2 increase or a 2 to 0 decrease of the number of bits on a subcarrier, according to the allowable bit swap commands defined in Table 11-2. + +The extended bit swap request is transmitted five consecutive times. + +### 11.2.5 Bit swap acknowledge + +NOTE – "Bit swap" will be used hereafter to refer to either a regular or an extended bit swap. + +Within 400 ms after receiving the bit swap request message, the transmitter shall send a bit swap acknowledge message, which shall contain the following: + +- a bit-swap acknowledge message header coded "111111112"; +- one message field, which consists of an eight-bit bit-swap acknowledge command followed by an eight-bit superframe counter number. The acknowledge command shall be coded "111111112"; the counter number indicates when the bit swap is to take place. This number shall be at least 47 greater than the counter number when the request was received (this corresponds to a minimum wait time of 800 ms). The new bit and/or transmit power table(s) shall then take effect starting from the first frame (frame 0) of an ADSL superframe, after the specified superframe counter number has been reached. That is, if the bit swap superframe counter number contained in the bit swap acknowledge message is *n*, then the new table(s) shall take effect starting from frame 0 of the (*n*+1)th ADSL superframe. + +See Table 11-5. + +**Table 11-5/G.992.1 – Format of the bit swap acknowledge** + +| Message header | Acknowledge command | Bit swap superframe counter number | +|-----------------------------------|-----------------------------------|------------------------------------| +| 11111111 2
(8 bits) | 11111111 2
(8 bits) | (8 bits) | + +The bit swap acknowledge is transmitted five consecutive times. + +### 11.2.6 Bit swap – Receiver + +The receiver shall start a timeout of 500 ± 20 ms from the moment it sends a bit swap request message. When no acknowledgement has been detected in this timeout interval, the receiver shall resend a bit swap request message (which shall have the same parameters) and restart the timeout. Only when an acknowledgement has been detected within the timeout interval shall the receiver prepare for a bit swap at the time specified in the acknowledge message. + +Upon timeout, the bit swap message shall be transmitted. However, after a finite (implementation dependent) number of unsuccessful retries, the receiver shall take recovery actions to accomplish bit swap; those recovery actions are also vendor discretionary. + +The receiver shall then wait until the superframe counter equals the value specified in the bit swap acknowledge message. Then, beginning with frame 0 of the next ADSL superframe the receiver shall: + +- Change the bit assignment of the appropriate subcarriers and perform tone reordering based on the new subcarrier bit assignment. +- Update applicable receiver parameters of the appropriate subcarriers to account for a change in their transmitted energy. + +NOTE – A new bit swap request shall only be sent after the previous bit swap has taken place or when the $500 \pm 20$ ms timeout has occurred while waiting for a bit swap acknowledge. + +### 11.2.7 Bit swap – Transmitter + +After transmitting the bit swap acknowledge, the transmitter shall wait until the superframe counter equals the value specified in the bit swap acknowledge. Then, beginning with frame 0 of the next ADSL superframe, the transmitter shall: + +- change the bit assignment of the appropriate subcarriers, and perform tone reordering based on the new subcarrier bit assignment; +- change the transmit energy in the appropriate subcarriers by the desired factor. + +If the transmitter receives a new bit swap request message while waiting, it shall immediately stop waiting and update the superframe counter for bit swap according to the new message. It shall restart the process for the newly arrived bit swap request message assuming that the new message equals the previous. + +## ANNEX A + +### Specific requirements for an ADSL system operating in the frequency band above POTS + +This annex defines those parameters of the ADSL system that have been left undefined in the body of this Recommendation because they are unique to an ADSL service that is frequency-division duplexed with POTS. + +#### A.1 ATU-C Functional Characteristics (pertains to clause 7) + +##### A.1.1 Pilot Frequency (supplements 7.11.1.2) + +The downstream pilot frequency shall be 276 kHz; that is, $n_{C-PILOT} = 64$ . + +##### A.1.2 ATU-C downstream transmit spectral mask (replaces 7.14) + +The band from 25 to 1104 kHz that is referred to is the widest possible band (used for ADSL over POTS implemented with overlapped spectrum). Limits defined within this band apply also to any narrower bands used. + +Figure A.1 shows a representative spectral mask for the transmit signal. The low-frequency stop-band is defined as the POTS band, the high-frequency stop-band is defined as frequencies greater than 1104 kHz. + +![Figure A.1/G.992.1 – ATU-C transmitter PSD mask. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, 1104, 3093, 4545, and 11 040. The y-axis has markers at -97.5, -92.5, -36.5, -90, and -50. The PSD mask is defined by several segments: 0 to 4 kHz is a flat floor at -97.5 dBm/Hz with a maximum power of +15 dBm; 4 to 25.875 kHz is a 21 dB/octave slope rising to -92.5 dBm/Hz; 25.875 to 1104 kHz is a flat peak at -36.5 dBm/Hz; 1104 to 3093 kHz is a -36 dB/octave slope; 3093 to 4545 kHz is a flat peak at -90 dBm/Hz; 4545 to 11 040 kHz is a flat peak at -90 dBm/Hz, with a note that the power in any 1 MHz sliding window above 4545 kHz shall be -50 dBm. A dashed line indicates the -50 dBm power level.](19d3d46ab06be40b6033e9669bfa7299_img.jpg) + +Figure A.1/G.992.1 – ATU-C transmitter PSD mask. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, 1104, 3093, 4545, and 11 040. The y-axis has markers at -97.5, -92.5, -36.5, -90, and -50. The PSD mask is defined by several segments: 0 to 4 kHz is a flat floor at -97.5 dBm/Hz with a maximum power of +15 dBm; 4 to 25.875 kHz is a 21 dB/octave slope rising to -92.5 dBm/Hz; 25.875 to 1104 kHz is a flat peak at -36.5 dBm/Hz; 1104 to 3093 kHz is a -36 dB/octave slope; 3093 to 4545 kHz is a flat peak at -90 dBm/Hz; 4545 to 11 040 kHz is a flat peak at -90 dBm/Hz, with a note that the power in any 1 MHz sliding window above 4545 kHz shall be -50 dBm. A dashed line indicates the -50 dBm power level. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|--------------------------|---------------------------------------------------------------------------------------------------------------------------| +| $0 < f < 4$ | -97.5, with max power in the in 0-4 kHz band of +15 dBm | +| $4 < f < 25.875$ | $-92.5 + 21 \times \log_2 (f/4)$ | +| $25.875 < f < 1104$ | -36.5 | +| $1104 < f < 3093$ | $-36.5 - 36 \times \log_2 (f/1104)$ | +| $3093 < f < 4545$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of $(-36.5 - 36 \times \log_2 (f/1104) + 60) \text{ dBm}$ | +| $4545 < f < 11 040$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – All PSD measurements are in 100 $\Omega$ ; the POTS band total power measurement is in 600 $\Omega$ . + +NOTE 2 – The breakpoint frequencies and PSD values are exact; the indicated slopes are approximate. + +NOTE 3 – Above 25.875 kHz, the peak PSD shall be measured with a 10 kHz resolution bandwidth. + +NOTE 4 – The power in a 1 MHz sliding window is measured in a 1 MHz bandwidth, starting at the measurement frequency. + +NOTE 5 – The step in the PSD mask at 4 kHz is to protect V.90 performance. Originally, the PSD mask continued the 21 dB/octave slope below 4 kHz hitting a floor of -97.5 dBm/Hz at 3400 Hz. It was recognized that this might impact V.90 performance, and so the floor was extended to 4 kHz. + +NOTE 6 – All PSD and power measurements shall be made at the U-C interface (see Figure 1-1); the signals delivered to the PSTN are specified in Annex E. + +**Figure A.1/G.992.1 – ATU-C transmitter PSD mask** + +### A.1.2.1 Passband PSD and response + +The average PSD within the used passband shall be no greater than -40 dBm/Hz reduced by power cut-back (see 10.4.5.1); the lower end of this passband depends on which service and duplexing option is used, and is manufacturer discretionary; the upper end depends on whether the signal is for initialization (see A.1.2.3.1) or steady state (see A.1.2.3.3). + +The passband ripple shall be no greater than +3.5 dB; the maximum PSD of $(-40 - 2n_{\text{PCB}} + 3.5) \text{ dBm/Hz}$ applies across the whole band from 25 kHz to 1104 kHz. + +The group delay variation over the passband shall not exceed 50 $\mu\text{s}$ . + +### **A.1.2.2 Stop-band PSDs** + +#### **A.1.2.2.1 Low frequency stop-band rejection** + +The total power in the voiceband (0 to 4 kHz) shall not exceed +15 dBm (see Recommendation G.996.1 for the method of measurement). + +In the transition band from 4 kHz to 25.875 kHz, the maximum PSD is given by a straight line on a log scale from $-92.5$ dBm/Hz, at just above 4 kHz, to $-36.5$ dBm/Hz, at 25.875 kHz; that is $(-92.5 + 21 \times \log(f/4)/\log(2))$ dBm/Hz. + +#### **A.1.2.2.2 High frequency stop-band rejection** + +The PSD shall decrease at a rate greater than or equal to 36 dB/octave from $(-40 + 3.5 - 2n_{\text{PCB}})$ dBm/Hz at the band edge (1.104 MHz) to $-90$ dBm/Hz at 3.093 MHz. Above 3.093 MHz the PSD shall not exceed $-90$ dBm/Hz. Additionally, there shall be less than $-50$ dBm of power measured in any 1 MHz sliding window above 4.545 MHz. + +#### **A.1.2.3 Transmit power spectral density and aggregate power level** + +There are three different PSD masks for the ATU-C transmit signal, depending on the type of signal sent. In all cases the power in the voiceband measured at the U-C interface and that is delivered to the Public Switched Telephone Network (PSTN) interface shall conform to the specification in A.1.2.2.1. + +The power emitted by the ATU-C is limited by the requirements in this subclause. Notwithstanding these requirements, it is assumed that the ADSL will comply with applicable national requirements on emission of electromagnetic energy. + +##### **A.1.2.3.1 All initialization signals (except C-ECT) starting with C-REVERB1** + +The nominal PSD in the band from 25.875 to 1104 kHz shall be set at $-40$ dBm/Hz for an aggregate transmit power not greater than 20.4 dBm. If measurement of the upstream power indicates that power cut-back is necessary, then the nominal PSD shall be set to a level of $-40 - 2n_{\text{PCB}}$ dBm/Hz (as described in 10.4.5.1). + +During the C-REVERB and C-SEGUE signals, all subcarriers from index $i$ to 255 shall be transmitted, with $i$ vendor discretionary (see A.1.2.1). However, at the vendor's discretion, one or more of these subcarriers may not be transmitted during the C-MEDLEY signal. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than 1 dB above the nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-39 - 2n_{\text{PCB}}$ dBm/Hz. + +##### **A.1.2.3.2 C-ECT** + +Because C-ECT is a vendor defined signal (see 10.4.7), the PSD specification shall be interpreted only as a maximum. This maximum level is $-39 - 2n_{\text{PCB}}$ dBm/Hz for the band from 25.875 to 1104 kHz. Subcarriers 1 to 5 may be used, but the power in the voiceband that is delivered to the PSTN interface shall conform to the specification given in A.1.2.2.1. + +### A.1.2.3.3 Steady-state data signal + +The nominal PSD in the band from 25.875 to 1104 kHz shall be set at $-40$ dBm/Hz. The nominal aggregate power shall be set at $-3.65 + 10\log(ncdown)$ dBm, where *ncdown* is the number of subcarriers used (i.e. with $b_i > 0$ ) (20.4 dBm if all subcarriers are used). The transmit PSD and aggregate power may, however, be changed from their nominal values in either of the following circumstances: + +- A power cut-back may have been applied, reducing the nominal PSD level to $-40 - 2n_{PCB}$ dBm/Hz (see 10.4.5.1). +- The bits and gains table (received from the ATU-R during initialization and possibly updated through bit swaps, see R-B&G in 10.9.14 and 11.2) may not allocate bits to some subcarriers and may finely adjust (i.e. within the range $-14.5$ to $+2.5$ dB) the transmit PSD level of others in order to equalize expected error rates on each of those subcarriers. +- Vendor discretionary transmit PSD levels for unused subcarriers (i.e. with $b_i = 0$ ). The maximum transmit PSD for these subcarriers is specified in b) and c) below. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than 1 dB above the finely adjusted nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-36.5 - 2n_{PCB}$ dBm/Hz. + +The transmit PSD of each subcarrier is defined as follows: + +- a) For the subcarriers with ( $b_i > 0$ ), the ATU-C transmitter shall transmit at PSD levels equal to that specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at C-MEDLEY transmit PSD level). The aggregate transmit power in these subcarriers shall not exceed $-3.65 + 10\log(ncdown_1) - 2n_{PCB}$ dBm by more than 0.7 dB, where *ncdown*1 is the number of these subcarriers (i.e. with $b_i > 0$ ). +- b) For the subcarriers with ( $b_i = 0$ and $g_i > 0$ ), the ATU-C transmitter should and is recommended to transmit at PSD levels equal to that specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at C-MEDLEY level), with a 4-QAM constellation point (which may change from symbol to symbol). The ATU-R receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers shall be no higher than the C-REVERB1 transmit PSD level $+ 10\log(g_i^2)$ dB. The aggregate transmit power in these subcarriers shall not exceed $-3.65 + 10\log(ncdown_2) - 2n_{PCB}$ dBm, where *ncdown*2 is the number of these subcarriers (i.e. with $b_i = 0$ and $g_i > 0$ ). +- c) For the subcarriers with ( $b_i = 0$ and $g_i = 0$ ), the ATU-C transmitter should and is recommended to transmit no power on those subcarriers. The ATU-R receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest *i* with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +The aggregate transmit power over the 25.875 to 1104 kHz band shall be no higher than $20.4 - 2n_{PCB}$ dBm, which is equivalent to an average transmit PSD of no higher than $-40 - 2n_{PCB}$ dBm/Hz. + +It is recommended that the $g_i$ values for subcarriers with $g_i > 0$ are constraint within $\pm 2.5$ dB with respect to $g_{sync}$ , during initialization and subsequent bit swaps, to avoid cyclostationary interference from the synchronization symbol. + +#### A.1.2.3.4 Synchronization symbol + +At initialization time, the sync symbol reference transmit PSD level shall be set at $-40 - 2n_{\text{PCB}} + 10\log(g_{\text{sync}}^2)$ dBm/Hz, with $g_{\text{sync}}^2$ defined as the average $g_i^2$ value over the used (i.e. $b_i > 0$ ) subcarriers. The sync symbol reference transmit PSD shall not be updated with used subcarrier gain changes during SHOWTIME. + +The transmit PSD level for those subcarriers with $g_i > 0$ shall be the sync symbol reference transmit PSD level. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +Since the $g_i$ are applied only to the data symbols, the transmit PSD of a synchronization symbol differs from the transmit PSD of a data symbol. These $g_i$ are calculated for the multipoint constellations in order to equalize the expected error rate on all subcarriers, and are therefore irrelevant for most of the 4-QAM modulated subcarriers of the synchronization symbol. + +#### A.1.3 ATU-C transmitter PSD mask for reduced NEXT + +Figure A.2 defines a spectral mask for the ATU-C transmitted signal, which results in reduced NEXT into the ADSL upstream band, relative to the mask in A.1.2. Adherence to this mask will in many cases result in improved upstream performance of the other ADSL systems in the same or adjacent binder group, with the improvement dependent upon the other interferers. This mask differs from the mask in A.1.2 only in the band from 4 kHz to 138 kHz. + +![Graph of PSD (dB) vs Frequency (kHz) for ATU-C transmitter. The graph shows a piecewise linear mask with various slopes and peaks. Key points include: 0-4 kHz floor at -97.5 dB with +15 dBm max power; 4-80 kHz slope of 4.63 dB/octave; 80-138 kHz slope of 36 dB/octave; 138-1104 kHz flat peak at -36.5 dB; 1104-3093 kHz slope of -36 dB/octave; 3093-4545 kHz peak at -90 dB with -50 dBm max power in any 1 MHz window; 4545-11040 kHz flat peak at -90 dB with -50 dBm max power in any 1 MHz window. Other labeled peaks include -92.5, -72.5, -44.2, and -49.2 dB.](38afb7a6accf13827afc86dc264de69b_img.jpg) + +Graph of PSD (dB) vs Frequency (kHz) for ATU-C transmitter. The graph shows a piecewise linear mask with various slopes and peaks. Key points include: 0-4 kHz floor at -97.5 dB with +15 dBm max power; 4-80 kHz slope of 4.63 dB/octave; 80-138 kHz slope of 36 dB/octave; 138-1104 kHz flat peak at -36.5 dB; 1104-3093 kHz slope of -36 dB/octave; 3093-4545 kHz peak at -90 dB with -50 dBm max power in any 1 MHz window; 4545-11040 kHz flat peak at -90 dB with -50 dBm max power in any 1 MHz window. Other labeled peaks include -92.5, -72.5, -44.2, and -49.2 dB. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|--------------------------|------------------------------------------------------------------------------------------------------------------| +| $0 < f < 4$ | -97.5, with max power in the in 0-4 kHz band of +15 dBm | +| $4 < f < 80$ | $-92.5 + 4.63 \times \log_2(f/4)$ | +| $80 < f < 138$ | $-72.5 + 36 \times \log_2(f/80)$ | +| $138 < f < 1104$ | -36.5 | +| $1104 < f < 3093$ | $-36.5 - 36 \times \log_2(f/1104)$ | +| $3093 < f < 4545$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of $(-36.5 - 36 \times \log_2(f/1104) + 60)$ dBm | +| $4545 < f < 11040$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – All PSD measurements are in 100 $\Omega$ ; the POTS band total power measurement is in 600 $\Omega$ . + +NOTE 2 – The breakpoint frequencies and PSD values are exact; the indicated slopes are approximate. + +NOTE 3 – Above 25.875 kHz, the peak PSD shall be measured with a 10 kHz resolution bandwidth. + +NOTE 4 – The power in a 1 MHz sliding window is measured in a 1 MHz bandwidth, starting at the measurement frequency. + +NOTE 5 – The step in the PSD mask at 4 kHz is to protect V.90 performance. Originally, the PSD mask continued the 21 dB/octave slope below 4 kHz hitting a floor of -97.5 dBm/Hz at 3400 Hz. It was recognized that this might impact V.90 performance, and so the floor was extended to 4 kHz. + +NOTE 6 – All PSD and power measurements shall be made at the U-C interface (see Figure 1-1); the signals delivered to the PSTN are specified in Annex E. + +**Figure A.2/G.992.1 – ATU-C transmitter PSD mask for reduced NEXT** + +## A.2 ATU-R (see clause 8) + +### A.2.1 Modulation by the inverse discrete Fourier transform (see 8.11.2) + +The modulating transform defines the relationship between the 64 real values $x_n$ and the $Z_i$ + +$$x_n = \sum_{i=0}^{63} \exp\left(\frac{j\pi ni}{32}\right) Z_i \quad (\text{A-1})$$ + +The encoder and scaler generate only 31 complex values of $Z_i$ (plus zero at DC and one real value if the Nyquist frequency is used). In order to generate real values of $x_n$ , these values shall be augmented so that the vector $Z$ has Hermitian symmetry. That is, + +$$Z_i = \text{conj}[Z_{64-i}] \text{ for } i = 33 \text{ to } 63 \quad (\text{A-2})$$ + +#### A.2.2 Synchronization symbol (supplements 8.11.3) + +The data pattern used in the synchronization symbol shall be the pseudo-random sequence PRU ( $d_n$ , for $n = 1$ to 64), defined by: + +$$d_n = 1 \quad \text{for } n = 1 \text{ to } 6 \quad (\text{A-3})$$ + +$$d_n = d_{n-5} \oplus d_{n-6} \quad \text{for } n = 7 \text{ to } 64 \quad (\text{A-4})$$ + +The bits are used as follows: the first pair of bits ( $d_1$ and $d_2$ ) is used for the DC and Nyquist subcarriers (the power assigned to them is, of course, zero, so the bits are effectively ignored); then the first and second bits of subsequent pairs shall be used to define the $X_i$ and $Y_i$ for $i = 1$ to 31 as shown in Table 7-13. + +The period of PRU is only 63 bits, so $d_{64} = d_1$ . + +The $d_1$ - $d_{96}$ are re-initialized for each symbol, so each symbol of R-REVERB1 uses the same data. + +#### A.2.3 Cyclic prefix (replaces 8.12) + +The cyclic prefix shall be used for all symbols beginning with segment C-REVERB3 of the initialization sequence, as defined in 10.7.2. + +The last 4 samples of the output of the IDFT ( $x_k$ for $k = 60$ to 63) shall be prepended to the block of 64 samples and read out to the DAC in sequence. That is, the subscripts, $k$ , of the DAC samples in sequence are 60...63, 0...63. + +#### A.2.4 ATU-R transmitter spectral mask (replaces 8.14) + +Figure A.3 shows a PSD mask for the transmitted signal. The passband is defined as frequency range over which the modem transmits, which may be narrower than the 25.875 to 138 kHz shown. The low-frequency stop-band is defined as the voiceband. + +![Figure A.3/G.992.1 – ATU-R transmitter PSD mask. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, 138, 307, 1221, 1630, and 11 040 kHz. The y-axis has markers at -97.5, -92.5, -34.5, -48, and -90 dBm/Hz. The PSD mask consists of several segments: a horizontal floor at -97.5 dBm/Hz from 0 to 4 kHz (with a note about 15 dBm total power in 0-4 kHz); a 21.5 dB/octave slope from 4 kHz to 25.875 kHz, reaching a -92.5 dBm/Hz peak; a horizontal peak at -34.5 dBm/Hz from 25.875 kHz to 138 kHz; a -48 dB/octave slope from 138 kHz to 307 kHz; a horizontal peak at -90 dBm/Hz from 307 kHz to 1221 kHz; a -48 dB/octave slope from 1221 kHz to 1630 kHz; and a horizontal peak at -90 dBm/Hz from 1630 kHz to 11 040 kHz. A note indicates that above 1630 kHz, the power in any 1 MHz sliding window should not exceed -50 dBm. The reference T1532690-99 is shown at the bottom right.](274bba7c7af3bbca5a07c8841f83b32a_img.jpg) + +Figure A.3/G.992.1 – ATU-R transmitter PSD mask. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 4, 25.875, 138, 307, 1221, 1630, and 11 040 kHz. The y-axis has markers at -97.5, -92.5, -34.5, -48, and -90 dBm/Hz. The PSD mask consists of several segments: a horizontal floor at -97.5 dBm/Hz from 0 to 4 kHz (with a note about 15 dBm total power in 0-4 kHz); a 21.5 dB/octave slope from 4 kHz to 25.875 kHz, reaching a -92.5 dBm/Hz peak; a horizontal peak at -34.5 dBm/Hz from 25.875 kHz to 138 kHz; a -48 dB/octave slope from 138 kHz to 307 kHz; a horizontal peak at -90 dBm/Hz from 307 kHz to 1221 kHz; a -48 dB/octave slope from 1221 kHz to 1630 kHz; and a horizontal peak at -90 dBm/Hz from 1630 kHz to 11 040 kHz. A note indicates that above 1630 kHz, the power in any 1 MHz sliding window should not exceed -50 dBm. The reference T1532690-99 is shown at the bottom right. + +| Frequency band f
(kHz) | Equation for line
(dBm/Hz) | +|----------------------------------|-------------------------------------------------------------------------------------------------------------------| +| $0 < f < 4$ | -97.5, with max power in the in 0-4 kHz band of +15 dBm | +| $4 < f < 25.875$ | $-92.5 + 21.5 \times \log_2(f/4)$ | +| $25.875 < f < 138$ | -34.5 | +| $138 < f < 307$ | $-34.5 - 48 \times \log_2(f/138)$ | +| $307 < f < 1221$ | -90 | +| $1221 < f < 1630$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of
$(-90 - 48 \times \log_2(f/1221) + 60)$ dBm | +| $1630 < f < 11\ 040$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – All PSD measurements are in 100 Ω; the POTS band total power measurement is in 600 Ω. +NOTE 2 – The breakpoint frequencies and PSD values are exact; the indicated slopes are approximate. +NOTE 3 – Above 25.875 kHz, the peak PSD shall be measured with a 10 kHz resolution bandwidth. +NOTE 4 – The power in a 1 MHz sliding window is measured in a 1 MHz bandwidth, starting at the measurement frequency. +NOTE 5 – The step in the PSD mask at 4 kHz is to protect V.90 performance. Originally, the PSD mask continued the 21.5 dB/octave slope below 4 kHz hitting a floor of -97.5 dBm/Hz at 3400 Hz. It was recognized that this might impact V.90 performance, and so the floor was extended to 4 kHz. +NOTE 6 – All PSD and power measurements shall be made at the U-C interface (see Figure 1-1); the signals delivered to the PSTN are specified in Annex E. + +**Figure A.3/G.992.1 – ATU-R transmitter PSD mask** + +#### A.2.4.1 Passband PSD and response + +The average PSD within the used passband shall be no greater than -38 dBm/Hz; the upper end of this passband depends on whether the signal is for initialization (see A.2.4.3.1) or steady state (see A.2.4.3.3). + +The passband ripple shall be no greater than +3.5 dB; the maximum PSD of -34.5 dBm/Hz applies across the whole band from 25 kHz to 138 kHz. + +The group delay variation over the passband shall not exceed 50 μs. + +#### A.2.4.2 Stop-band PSDs + +##### A.2.4.2.1 Low frequency stop-band rejection + +The total power in the voiceband (0 Hz to 4 kHz) shall not exceed +15 dBm (see Recommendation G.996.1 for the method of measurement). + +In the transition band from 4 kHz to 25.875 kHz, the maximum PSD is given by a straight line on a log scale from $-92.5$ dBm/Hz, at just above 4 kHz, to $-34.5$ dBm/Hz at 25.875 kHz; that is $(-92.5 + 21.5 \times \log(f/4)/\log(2))$ dBm/Hz. + +##### A.2.4.2.2 High frequency stop-band rejection + +The PSD shall decrease at 48 dB/octave from $(-38 \text{ dBm/Hz} + 3.5 \text{ dB})$ at the band-edge (138 kHz) to $-90$ dBm/Hz at 307 kHz. In addition, the power in any 1 MHz sliding window from 1630 kHz to 11.04 MHz shall not exceed $-50$ dBm. + +#### A.2.4.3 Transmit power spectral density and aggregate power level + +There are three different PSD masks for the ATU-C transmit signal, depending on the type of signal sent. In all cases the power in the voiceband measured at the U-R interface and that is delivered to the POTS interface shall conform to the specification in A.2.4.2.1. + +##### A.2.4.3.1 All initialization signals (except R-ECT) starting with R-REVERB1 + +The nominal PSD in the band from 25 to 138 kHz shall be $-38$ dBm/Hz for an aggregate power of not greater than 12.5 dBm. + +During the R-REVERB and R-SEGUE signals, all subcarriers from index $i$ to 31 shall be transmitted, with $i$ vendor discretionary (see A.2.4.1). However, at the vendor's discretion, one or more of these subcarriers may not be transmitted during the R-MEDLEY signal. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than 1 dB above the nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-37$ dBm/Hz. + +##### A.2.4.3.2 R-ECT + +Since R-ECT is a vendor-defined signal (see 10.5.4), the PSD specification should be interpreted only as a maximum. This maximum level is $-37$ dBm/Hz for the band from 25.875 to 138 kHz. Subcarriers 1-5 may be used, but the power in the voiceband that is delivered to the POTS interface shall conform to the specification given in A.2.4.2.1. + +##### A.2.4.3.3 Steady-state data signal + +The nominal PSD in the band from 25.875 to 138 kHz shall be set at $-38$ dBm/Hz. The nominal aggregate power shall be set at $-1.65 + 10\log(ncup)$ dBm, where $ncup$ is the number of subcarriers used (i.e. with $b_i > 0$ ) (12.5 dBm if all subcarriers are used). The transmit PSD and aggregate power may, however, be changed from their nominal values in either of the following circumstances: + +- The bits and gains table (received from the ATU-C during initialization and possibly updated through bit swaps, see C-B&G in 10.8.13 and 11.2) may not allocate bits to some subcarriers and may finely adjust (i.e. within the range $-14.5$ to $+2.5$ dBm) the transmit PSD level of others in order to equalize expected error rates on each of those subcarriers. +- Vendor discretionary transmit PSD levels for unused subcarriers (i.e. $b_i = 0$ ). The maximum transmit PSD for these subcarriers is specified in b) and c) below. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than 1 dB above the finely adjusted nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-34.5$ dBm/Hz. + +The transmit PSD of each subcarrier is defined as follows: + +- a) For the subcarriers with ( $b_i > 0$ ), the ATU-R transmitter shall transmit at PSD levels equal to that specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at R-MEDLEY transmit PSD level). The aggregate transmit power in these subcarriers shall not exceed $-1.65 + 10\log(ncup_1)$ dBm by more than 0.7 dB, where $ncup_1$ is the number of these subcarriers (i.e. with $b_i > 0$ ). +- b) For the subcarriers with ( $b_i = 0$ and $g_i > 0$ ), the ATU-R transmitter should and is recommended to transmit at PSD levels equal to that specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at R-MEDLEY level), with a 4-QAM constellation point (which may change from symbol to symbol). The ATU-C receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers shall be no higher than the R-REVERB1 transmit PSD level + $10\log(g_i^2)$ dB. The aggregate transmit power in these subcarriers shall not exceed $-1.65 + 10\log(ncup_2)$ dBm, where $ncup_2$ is the number of these subcarriers (i.e. with $b_i = 0$ and $g_i > 0$ ). +- c) For the subcarriers with ( $b_i = 0$ and $g_i = 0$ ), the ATU-R transmitter should and is recommended to transmit no power on those subcarriers. The ATU-C receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +The aggregate transmit power over the 25.875 to 138 kHz band shall be no higher than 12.5 dBm, which is equivalent to an average transmit PSD of no higher than $-38$ dBm/Hz. + +It is recommended that the $g_i$ values for subcarriers with $g_i > 0$ are constraint within $\pm 2.5$ dB with respect to $g_{sync}$ , during initialization and subsequent bit swaps, to avoid cyclostationary interference from the synchronization symbol. + +#### A.2.4.3.4 Synchronization symbol + +At initialization time, the sync symbol reference transmit PSD level shall be set at $-38 + 10\log(g_{sync}^2)$ dBm/Hz, with $g_{sync}^2$ defined as the average $g_i^2$ value over the used (i.e. $b_i > 0$ ) subcarriers. The sync symbol reference transmit PSD shall not be updated with used subcarrier gain changes during SHOWTIME. + +The transmit PSD level for those subcarriers with $g_i > 0$ shall be the sync symbol reference transmit PSD level. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +Since the $g_i$ are applied only to the data symbols, the transmit PSD of a synchronization symbol differs from the transmit PSD of a data symbol. These $g_i$ are calculated for the multipoint constellations in order to equalize the expected error rate on all subcarriers, and are therefore irrelevant for most of the 4-QAM modulated subcarriers of the synchronization symbol. + +#### A.2.5 Nyquist frequency (supplements 8.11.1.2) + +The upstream Nyquist frequency shall be at subcarrier #32 ( $f = 138$ kHz). + +### A.3 Initialization (see clause 10) + +#### A.3.1 Power cut-back (supplements 10.4.5.1) + +If the total upstream power measured on subcarriers 7-18 during R-REVERB1 is greater than 3 dBm, then the PSD for C-REVERB1 and all subsequent downstream signals shall be as shown in Table A.1. + +**Table A.1/G.992.1 – Power cut-back: downstream PSD as a function of upstream received power** + +| | | | | | | | | +|---------------------------------|-----|-----|-----|-----|-----|-----|-----| +| Upstream received power (dBm) < | 3 | 4 | 5 | 6 | 7 | 8 | 9 | +| Max downstream PSD (dBm/Hz) | -40 | -42 | -44 | -46 | -48 | -50 | -52 | + +This chosen level shall become the reference level for all subsequent gain calculations. + +#### A.3.2 Estimated average upstream loop attenuation (see 10.8.9.1) + +With the allowable transmit PSDs -38 dBm/Hz over the 25.875 to 138 kHz band, the total transmit power, as used for this calculation, shall be 12.5 dBm. + +#### A.3.3 Estimated average downstream loop attenuation (supplements 10.9.8.1) + +With the allowable transmit PSDs as defined in Table 10-7 (-40 dBm/Hz to -52 dBm/Hz) and a maximum bandwidth of approximately 1074 kHz if using overlapped spectrum, the total transmit power, as used for this calculation, may range from a maximum of 20.3 dBm in steps of -2 dB to a minimum of 8.3 dBm. + +#### A.3.4 C-PILOT1 (supplements 10.4.2) + +$f_{\text{C-PILOT1}} = 276$ kHz that is, $N_{\text{C-PILOT1}} = 64$ . + +#### A.3.5 R-REVERB1 (see 10.5.2) + +The data pattern used in R-REVERB1 is the pseudo-random upstream sequence PRU defined in A.2.2 and repeated here for convenience: + +$$d_n = 1 \quad \text{for } n = 1 \text{ to } 6 \quad (\text{A-5})$$ + +$$d_n = d_{n-5} \oplus d_{n-6} \quad \text{for } n = 7 \text{ to } 64 \quad (\text{A-6})$$ + +The bits defined in 10.5.2 shall be used as follows: the first pair of bits ( $d_1$ and $d_2$ ) is used for the DC and Nyquist subcarriers (the power assigned to them is, of course, zero, so the bits are effectively ignored); then the first and second bits of subsequent pairs are used to define the $X_i$ and $Y_i$ for $i = 1$ to 31 as defined for C-REVERB1 in Table 7-13. Although data bits are defined for all the subcarriers, the subcarriers actually transmitted during R-REVERB1 start from a vendor discretionary subcarrier index (see A.2.4.3.1). No gain scaling shall be applied to any subcarrier. + +#### A.3.6 C-ECT (see 10.4.7) + +The level of the ADSL signal in the frequency band from 0 to about 10 kHz that leaks through the POTS low-pass filter is tightly limited (see 7.14). Therefore it is recommended that subcarriers 1-4 not be used for C-ECT, or, at least, that they be transmitted at a much lower level. + +#### A.3.7 R-ECT (see 10.5.4) + +The level of the ADSL signal in the frequency band from 0 to about 10 kHz that leaks through the POTS low-pass filter is tightly limited (see Annex E). Therefore it is recommended that subcarriers 1-4 not be used for R-ECT, or, at least, that they be transmitted at a much lower level. + +### **A.3.8 C-MSG2 (supplements 10.8.9)** + +$n_{1C-MSG2} = 43$ + +$n_{2C-MSG2} = 91$ + +### **A.3.9 R-MSG2 (supplements 10.9.8)** + +$N_{1R-MSG2} = 10$ + +$N_{2R-MSG2} = 20$ + +## **A.4 Electrical characteristics (new)** + +This subclause specifies the combination of ATU-x and high-pass filter, as shown in Figure 1-1; further information about the low-pass filter is specified in Annex E. + +### **A.4.1 DC characteristics** + +All requirements of this Recommendation shall be met in the presence of all POTS loop currents from 0 mA to 100 mA, and differential loop voltages as follows: + +- DC voltages of 0 V to minus 60 V. +- Ringing signals no larger than 103 V rms at any frequency from 20 to 30 Hz with a DC component in the range from 0 V to minus 60 V. +- The input DC resistance of the ATU-x at the U-x interface shall be greater than or equal to 5 M $\Omega$ . + +NOTE – The most common implementation of the splitter filters is with the low-pass and high-pass connected in parallel at the U-x port. In this arrangement the high-pass filter will typically block DC with capacitors. + +### **A.4.2 Voiceband characteristics** + +#### **A.4.2.1 Input impedance** + +The imaginary part of the ATU-x input impedance, as measured at the U-x interface, at 4 kHz shall be in the range of 1.1-2.0 k $\Omega$ (approximately equivalent to a 20-34 nF capacitor) for the ATU-R (or the ATU-C that has an integrated splitter and high-pass function) and in the range of 500 $\Omega$ to 1.0 k $\Omega$ (approximately equivalent to 40-68 nF) for the ATU-C designed to be used with an external splitter. In both cases, the imaginary part of the impedance shall increase monotonically below 4 kHz. + +Refer to Annex E for additional information. + +#### **A.4.2.2 ADSL noise interference into the POTS circuit** + +This is the specification for the voiceband PSD of the ATU-C and ATU-R (see 7.14 and 8.14, respectively). + +### A.4.3 ADSL band characteristics + +#### A.4.3.1 Longitudinal balance + +Longitudinal balance at the U-C and U-R interfaces shall be >40 dB over the frequency range 30 kHz to 1104 kHz. If only the HPF part of the POTS splitter is integrated in the ATU, the measurement of the longitudinal balance in the ADSL band shall be performed as shown in Figure A.4. If both the LPF and the HPF parts of the POTS splitter are integrated in the ATU, the measurement of the longitudinal balance in the ADSL band shall be performed with the PSTN and POTS interfaces terminated with ZTC and ZTR, respectively, as shown in Figure A.5. Longitudinal balance is given by the equation: + +$$LBal = 20 \log \left| \frac{e_l}{e_m} \right| \text{ dB} \quad (\text{A-7})$$ + +where: + +- $e_l$ = the applied longitudinal voltage (referenced to the building or green wire ground of the ATU); +- $e_m$ = the resultant metallic voltage appearing across a terminating resistor. + +![Figure A.4/G.992.1 – Longitudinal balance above 30 kHz measurement method (only HPF integrated). The diagram shows an ATU connected to a line via an HPF. At the U-C/U-R interface, the line is terminated with two 50 Ω resistors (±0.03%) in series. A measuring set (well balanced) is connected across these resistors to measure the metallic voltage e_m. A longitudinal signal generator is connected between the line and ground to apply a longitudinal voltage e_l. The diagram is labeled T1533110-99.](a8bcad776c8f979f6ca27eebabac4af9_img.jpg) + +Figure A.4/G.992.1 – Longitudinal balance above 30 kHz measurement method (only HPF integrated). The diagram shows an ATU connected to a line via an HPF. At the U-C/U-R interface, the line is terminated with two 50 Ω resistors (±0.03%) in series. A measuring set (well balanced) is connected across these resistors to measure the metallic voltage e\_m. A longitudinal signal generator is connected between the line and ground to apply a longitudinal voltage e\_l. The diagram is labeled T1533110-99. + +**Figure A.4/G.992.1 – Longitudinal balance above 30 kHz measurement method (only HPF integrated)** + +![Figure A.5/G.992.1 – Longitudinal balance above 30 kHz measurement method (HPF and LPF integrated). The diagram shows an ATU connected to a line via both an HPF and an LPF. The POTS/PSTN interface is terminated with ZTC=900 Ω and ZTR=600 Ω. At the U-C/U-R interface, the line is terminated with two 50 Ω resistors (±0.03%) in series. A measuring set (well balanced) is connected across these resistors to measure the metallic voltage e_m. A longitudinal signal generator is connected between the line and ground to apply a longitudinal voltage e_l. The diagram is labeled T1532700-99.](09db1d3c990a8ce8a2e8a35bc93cfb5f_img.jpg) + +Figure A.5/G.992.1 – Longitudinal balance above 30 kHz measurement method (HPF and LPF integrated). The diagram shows an ATU connected to a line via both an HPF and an LPF. The POTS/PSTN interface is terminated with ZTC=900 Ω and ZTR=600 Ω. At the U-C/U-R interface, the line is terminated with two 50 Ω resistors (±0.03%) in series. A measuring set (well balanced) is connected across these resistors to measure the metallic voltage e\_m. A longitudinal signal generator is connected between the line and ground to apply a longitudinal voltage e\_l. The diagram is labeled T1532700-99. + +**Figure A.5/G.992.1 – Longitudinal balance above 30 kHz measurement method (HPF and LPF integrated)** + +**Specific requirements for an ADSL system operating in the frequency band above ISDN +as defined in ITU-T Recommendation G.961 Appendices I and II** + +This annex defines those parameters of the ADSL system that have been left undefined in the body of this Recommendation because they are unique to an ADSL service that is frequency-division duplexed with ISDN-BA on the same subscriber line ADSL. The scope is to establish viable ways enabling the simultaneous deployment of asymmetric services and 160 kbit/s (2B+D) Basic Rate Access with the constraint to use existing transmission technologies as those specified in Recommendation G.961 Appendices I and II. + +**B.1 ATU Functional Characteristics (see clause 7)** + +The ADSL signals described herein shall be allocated above the operating band of ISDN-BA signals based on 2B1Q/4B3T line signals as those defined in Recommendation G.961 Appendices I and II. In order to allow sufficient upstream bandwidth capacity, the ATU-R shall have a transmission bandwidth making use of tones 33 to 63. The use of an extended range making use of tones between 1 and 63 is optional. + +The IDFT implementation at the ATU-R side shall be implemented as follows. Tones 33 to 63 will contain complex values generated by the encoder and scaler. The values in tones 1 to 31 will be: + +- a) mirrored complex-conjugate of tones 33-63 if the ATU-R transmitter uses only 32 tones (tone #32 = 0); +- b) zero if the ATU-R transmitter uses 64 tones and the ATU-C receiver uses 32 tones (tone #32 = 0); +- c) complex data generated by the encoder and scaler if both the ATU-R transmitter and ATU-C receiver use 64 tones (tone 32 also equals value generated by encoder and scaler). + +The information whether the upstream transmitter and/or receiver uses 32 or 64 tones is negotiated via G.994.1 using the bits defined in 10.2 and 10.3. + +**B.1.1 Data Subcarriers (see 7.11.1.1)** + +The channel analysis signal defined in 10.6.6 allows for a maximum of 255 carriers (at frequencies $n\Delta f$ , $n = 1$ to 255) to be used, but for this service the lower limit of $n$ is 33. The use of tones below 33 is optional. Frequency Division Duplexing (FDD) may be used to separate the upstream and downstream signals, and the lower limit on $n$ is determined by the up/down splitting filters. The cut-off frequencies of these filters are at the discretion of the manufacturer, and the range of usable $n$ is determined during the channel estimation. + +**B.1.2 Pilot Frequency (see 7.11.1.2)** + +The downstream pilot frequency shall be 414 kHz; that is, $N_{\text{PILOT}} = 96$ . + +**B.1.3 Downstream transmit spectral mask (replaces 7.14)** + +Figure B.1 shows the spectral mask for the transmit signal. The low-frequency stop-band is the upstream band, the high-frequency stop-band is defined as frequencies greater than 1104 kHz. + +![Figure B.1/G.992.1 – ATU-C transmitter PSD mask. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 50(70), 80(90), 138, 1104, 3093, 4545, and 11 040. The PSD curve starts at -90 dBm/Hz for f < 50(70) kHz, rises with a 12 dB/octave slope to -36.5 dBm/Hz at 138 kHz, remains constant at -36.5 dBm/Hz until 1104 kHz, then falls with a -36 dB/octave slope to -90 dBm/Hz at 3093 kHz. From 3093 kHz to 4545 kHz, the PSD is a dashed line representing a -50 dBm power limit in any 1 MHz sliding window. Above 4545 kHz, the PSD is a solid line at -90 dBm/Hz, with a dashed line below it representing the -50 dBm power limit in any 1 MHz sliding window above 4545 kHz. A shaded region is shown between 50(70) and 80(90) kHz.](782dc840510be74b2f990d9468ee2266_img.jpg) + +PSD in dBm/Hz + +Measurements are into 100 ohms resistive termination + +12 dB/octave + +-90 dBm/Hz peak + +-36.5 peak + +-36 dB/octave + +-90 dBm/Hz peak + +-50 dBm power in any 1 MHz sliding window above 4545 kHz + +Frequency in kHz + +T1532710-99 + +Figure B.1/G.992.1 – ATU-C transmitter PSD mask. The graph shows Power Spectral Density (PSD) in dBm/Hz on the y-axis versus Frequency in kHz on the x-axis. The x-axis has markers at 0, 50(70), 80(90), 138, 1104, 3093, 4545, and 11 040. The PSD curve starts at -90 dBm/Hz for f < 50(70) kHz, rises with a 12 dB/octave slope to -36.5 dBm/Hz at 138 kHz, remains constant at -36.5 dBm/Hz until 1104 kHz, then falls with a -36 dB/octave slope to -90 dBm/Hz at 3093 kHz. From 3093 kHz to 4545 kHz, the PSD is a dashed line representing a -50 dBm power limit in any 1 MHz sliding window. Above 4545 kHz, the PSD is a solid line at -90 dBm/Hz, with a dashed line below it representing the -50 dBm power limit in any 1 MHz sliding window above 4545 kHz. A shaded region is shown between 50(70) and 80(90) kHz. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|-----------------------------|--------------------------------------------------------------------------------------------------------------------------| +| $0 < f < 50(70)$ | -90 | +| $>f_1=50(70) < f < 80(90)$ | $-90 + 12 \times \log_2(f/f_1)$ | +| $80(90) < f < 138$ | Note 2 | +| $138 < f < 1104$ | -36.5 | +| $1104 < f < 3093$ | $-36.5 - 36 \times \log_2(f/1104)$ | +| $3093 < f < 4545$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of $(-36.5 - 36 \times \log_2(f/1104) + 60) \text{ dBm}$ | +| $4545 < f < 11 \text{ 040}$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – 50 and 80 kHz are frequency limits referring to ADSL over ISDN lines operating with 2B1Q code (G.961 Appendix II). 70 and 90 kHz are frequency limits referring to ADSL over ISDN lines operating with 4B3T code (G.961 Appendix I). + +NOTE 2 – The value of PSD in this region depends on the low-pass and high-pass filter designs. The filters affect the ISDN-BA performance when combined with ADSL in two ways: + +- 1) the residual ADSL power, filtered by the high pass and received by the ISDN-BA receiver as noise; +- 2) the amplitude and phase distortion introduced by low-pass filters. + +It is expected that the degradation impact on the ISDN-BA line system performance be not more than 4.5 dB and 4 dB, for 2B1Q and 4B3T line codes respectively, at the insertion loss reference frequency. + +Figure B.1/G.992.1 – ATU-C transmitter PSD mask + +The maximum level of the PSD of the ADSL signal measured at the ISDN port of the splitter shall not exceed the limits defined in the first two rows of the table in Figure B.1. + +All PSD measurements made at the Line port of the ISDN splitter shall use a 100 $\Omega$ resistive reference impedance. + +All PSD measurements made at the ISDN port of the ISDN splitter shall use the design impedance of ISDN-BA for 2B1Q and 4B3T respectively as defined in ETSI TS 102 080 (V1.3.1). + +### B.1.3.1 Passband PSD and response + +The average PSD within the used passband shall be no greater than -40 dBm/Hz reduced by power cut-back in multiples of 2 dB; the lower end of this passband depends on which service and duplexing option is used, and is manufacturer discretionary; the upper end depends on whether the signal is for initialization (see B.2.2.3.1) or steady state (see B.2.2.3.2). + +The passband ripple shall be no greater than +3.5 dB; the maximum PSD of $(-40 - 2n_{\text{PCB}} + 3.5)$ dBm/Hz applies across the whole band from 138 kHz to 1104 kHz. + +The group delay variation over the passband shall not exceed 50 $\mu\text{s}$ . + +### **B.1.3.2 Transmit power spectral density and Nominal aggregate power level** + +There are two different PSD masks for the ATU-C transmit signal, depending on the type of signal sent. + +The power emitted by the ATU-C is limited by the requirements in this subclause. Notwithstanding these requirements, it is assumed that the ADSL will comply with applicable national requirements on emission of electromagnetic energy. + +#### **B.1.3.2.1 All initialization signals starting with C-REVERB1** + +The nominal PSD in the band from 138 to 1104 kHz shall be set at $-40$ dBm/Hz for an aggregate transmit power not greater than 19.9 dBm. If measurement of the upstream power indicates that power cut-back is necessary, then the nominal PSD shall be set to a level of $-40 - 2n_{\text{PCB}}$ dBm/Hz as described in 10.4.5.1. + +During the C-REVERB and C-SEGUE signals, all subcarriers from index $i$ to 255 shall be transmitted, with $i$ vendor discretionary (see B.1.3.1). However, at the vendor's discretion, one or more of these subcarriers may not be transmitted during the C-MEDLEY signal. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than 1 dB above the nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-39 - 2n_{\text{PCB}}$ dBm/Hz. + +#### **B.1.3.2.2 Steady-state data signal** + +The nominal PSD in the band from 138 to 1104 kHz shall be set at $-40$ dBm/Hz. The nominal aggregate power shall be set at $-3.65 + 10\log(ncdown)$ dBm, where $ncdown$ is the number of subcarriers used (i.e. with $b_i > 0$ ) (19.9 dBm if all subcarriers are used). The transmit PSD and aggregate power may, however, be changed from their nominal values in either of the following circumstances: + +- A power cut-back may have been applied, reducing the nominal PSD level to $-40 - 2n_{\text{PCB}}$ dBm/Hz (see 10.4.5.1). +- The bits and gains table (received from the ATU-R during initialization and possibly updated through bit swaps, see R-B&G in 10.9.14 and 11.2) may not allocate bits to some subcarriers and may finely adjust (i.e. within the range $-14.5$ to $+2.5$ dB) the transmit PSD level of others in order to equalize expected error rates on each of those subcarriers. +- Vendor discretionary transmit PSD levels for unused subcarriers (i.e. with $b_i = 0$ ). The maximum transmit PSD for these subcarriers is specified in b) and c) below. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than 1 dB above the finely adjusted nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-36.5 - 2n_{\text{PCB}}$ dBm/Hz. + +The transmit PSD of each subcarrier is defined as follows: + +- a) For the subcarriers with $(b_i > 0)$ , the ATU-C transmitter shall transmit at PSD levels equal to those specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at C-MEDLEY transmit PSD level). The aggregate transmit power in these subcarriers shall not exceed $-3.65 + 10\log(ncdown_1) - 2n_{\text{PCB}}$ dBm by more than 0.7 dB, where $ncdown_1$ is the number of these subcarriers (i.e. with $b_i > 0$ ). + +- b) For the subcarriers with ( $b_i = 0$ and $g_i > 0$ ), the ATU-C transmitter should and is recommended to transmit at PSD levels equal to those specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at C-MEDLEY level), with a 4-QAM constellation point (which may change from symbol to symbol). The ATU-R receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers shall be no higher than the C-REVERB1 transmit PSD level + $10\log(g_i^2)$ dB. The aggregate transmit power in these subcarriers shall not exceed $-3.65 + 10\log(ncdown_2) - 2n_{PCB}$ dBm, where $ncdown_2$ is the number of these subcarriers (i.e. with $b_i = 0$ and $g_i > 0$ ). +- c) For the subcarriers with ( $b_i = 0$ and $g_i = 0$ ), the ATU-C transmitter should and is recommended to transmit no power on those subcarriers. The ATU-R receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +The aggregate transmit power over the 138 to 1104 kHz band shall be no higher than $19.9 - 2n_{PCB}$ dBm, which is equivalent to an average transmit PSD of no higher than $-40 - 2n_{PCB}$ dBm/Hz. + +It is recommended that the $g_i$ values for subcarriers with $g_i > 0$ are constraint within $\pm 2.5$ dB with respect to $g_{sync}$ , during initialization and subsequent bit swaps, to avoid cyclostationary interference from the synchronization symbol. + +#### B.1.3.2.3 Synchronization symbol + +At initialization time, the sync symbol reference transmit PSD level shall be set at $-40 - 2n_{PCB} + 10\log(g_{sync}^2)$ dBm/Hz, with $g_{sync}^2$ defined as the average $g_i^2$ value over the used (i.e. $b_i > 0$ ) subcarriers. The sync symbol reference transmit PSD shall not be updated with used subcarrier gain changes during SHOWTIME. + +The transmit PSD level for those subcarriers with $g_i > 0$ shall be the sync symbol reference transmit PSD level. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +Since the $g_i$ are applied only to the data symbols, the transmit PSD of a synchronization symbol differs from the transmit PSD of a data symbol. These $g_i$ are calculated for the multipoint constellations in order to equalize the expected error rate on all subcarriers, and are therefore irrelevant for most of the 4-QAM modulated subcarriers of the synchronization symbol. + +## B.2 ATU-R functional characteristics (see clause 8) + +### B.2.1 ATU-R transmit reference models + +The ATU-R reference model for STM transport is given in Figure B.2. The ATU-R reference model for ATM transport is given in Figure B.3. + +![Figure B.2/G.992.1 – ATU-R transmitter reference mode for STM transport. This block diagram shows the signal processing flow for STM transport. Inputs LS0, LS1, and LS2 enter a 'Mux/Sync Control' block. A 'T-R' input provides 'EOC/AOC' signals. The output of the 'Mux/Sync Control' is split into two paths: one through 'crc_f' and 'scrambler & FEC' to point 'A' (Mux Data Frame), and another through 'crc_i', 'scrambler & FEC', and an 'Interleaver' to point 'B' (FEC Output Data Frame). Both paths converge at point 'C' (Constellation Encoder Input Data Frame). External 'Bits' and 'Bits and Gains' are also inputs at this stage. The signal then passes through 'Tone ordering', 'Constellation encoder and gain scaling', and 'IDFT'. The IDFT output, with indices 127, 126, 120, 1, and n=0, enters an 'Output Parallel/Serial Buffer'. The buffer output goes to 'DAC and analogue processing', which produces the final output. Reference points A, B, and C are marked along the bottom with vertical dashed lines.](893d65bf826925a7283359b1672010a0_img.jpg) + +Figure B.2/G.992.1 – ATU-R transmitter reference mode for STM transport. This block diagram shows the signal processing flow for STM transport. Inputs LS0, LS1, and LS2 enter a 'Mux/Sync Control' block. A 'T-R' input provides 'EOC/AOC' signals. The output of the 'Mux/Sync Control' is split into two paths: one through 'crc\_f' and 'scrambler & FEC' to point 'A' (Mux Data Frame), and another through 'crc\_i', 'scrambler & FEC', and an 'Interleaver' to point 'B' (FEC Output Data Frame). Both paths converge at point 'C' (Constellation Encoder Input Data Frame). External 'Bits' and 'Bits and Gains' are also inputs at this stage. The signal then passes through 'Tone ordering', 'Constellation encoder and gain scaling', and 'IDFT'. The IDFT output, with indices 127, 126, 120, 1, and n=0, enters an 'Output Parallel/Serial Buffer'. The buffer output goes to 'DAC and analogue processing', which produces the final output. Reference points A, B, and C are marked along the bottom with vertical dashed lines. + +Figure B.2/G.992.1 – ATU-R transmitter reference mode for STM transport + +![Figure B.3/G.992.1 – ATU-R transmitter reference model for ATM transport. This block diagram shows the signal processing flow for ATM transport. Inputs ATM0 and ATM1 enter 'Cell TC' blocks, which output LS0 and LS1 respectively. These enter a 'Mux/Sync Control' block. A 'T-R' input provides 'EOC/AOC' signals. The output of the 'Mux/Sync Control' is split into two paths: one through 'crc_f' and 'scrambler & FEC' to point 'A' (Mux Data Frame), and another through 'crc_i', 'scrambler & FEC', and an 'Interleaver' to point 'B' (FEC Output Data Frame). Both paths converge at point 'C' (Constellation Encoder Input Data Frame). External 'Bits' and 'Bits and Gains' are also inputs at this stage. The signal then passes through 'Tone ordering', 'Constellation encoder and gain scaling', and 'IDFT'. The IDFT output, with indices 127, 126, 120, 1, and n=0, enters an 'Output Parallel/Serial Buffer'. The buffer output goes to 'DAC and analogue processing', which produces the final output. Reference points A, B, and C are marked along the bottom with vertical dashed lines.](de18140c2e0030a43004b58338467655_img.jpg) + +Figure B.3/G.992.1 – ATU-R transmitter reference model for ATM transport. This block diagram shows the signal processing flow for ATM transport. Inputs ATM0 and ATM1 enter 'Cell TC' blocks, which output LS0 and LS1 respectively. These enter a 'Mux/Sync Control' block. A 'T-R' input provides 'EOC/AOC' signals. The output of the 'Mux/Sync Control' is split into two paths: one through 'crc\_f' and 'scrambler & FEC' to point 'A' (Mux Data Frame), and another through 'crc\_i', 'scrambler & FEC', and an 'Interleaver' to point 'B' (FEC Output Data Frame). Both paths converge at point 'C' (Constellation Encoder Input Data Frame). External 'Bits' and 'Bits and Gains' are also inputs at this stage. The signal then passes through 'Tone ordering', 'Constellation encoder and gain scaling', and 'IDFT'. The IDFT output, with indices 127, 126, 120, 1, and n=0, enters an 'Output Parallel/Serial Buffer'. The buffer output goes to 'DAC and analogue processing', which produces the final output. Reference points A, B, and C are marked along the bottom with vertical dashed lines. + +Figure B.3/G.992.1 – ATU-R transmitter reference model for ATM transport + +### B.2.2 ATU-R Upstream transmit spectral mask (replaces 8.14) + +Figure B.4 shows the spectral mask for the transmit signal. The low-frequency stop-band is defined as the ISDN band, the high-frequency stop-band is defined as frequencies greater than 276 kHz. + +![Figure B.4/G.992.1 – ATU-R transmitter PSD mask. The graph plots PSD (dBm/Hz) against Frequency (kHz). It starts at -90 dBm/Hz from 0 to 50(70) kHz, then rises at 12 dB/octave to 80(90) kHz. A shaded region exists between 80(90) and 138 kHz. From 138 to 276 kHz, it is flat at -34.5 peak. It then drops at -48 dB/octave to -90 dBm/Hz at 614 kHz. It stays flat at -90 until 1221 kHz. Between 1221 and 1630 kHz, there is a dashed line indicating a transition. From 1630 to 11 040 kHz, it is flat at -90 dBm/Hz peak, with a note about -50 dBm power in any 1 MHz sliding window above 1630 kHz.](cdf78577d07f3375edf8d981fc288d6b_img.jpg) + +PSD in dBm/Hz + +Measurements are into 100 ohms resistive termination + +Frequency in kHz + +T1532740-99 + +Figure B.4/G.992.1 – ATU-R transmitter PSD mask. The graph plots PSD (dBm/Hz) against Frequency (kHz). It starts at -90 dBm/Hz from 0 to 50(70) kHz, then rises at 12 dB/octave to 80(90) kHz. A shaded region exists between 80(90) and 138 kHz. From 138 to 276 kHz, it is flat at -34.5 peak. It then drops at -48 dB/octave to -90 dBm/Hz at 614 kHz. It stays flat at -90 until 1221 kHz. Between 1221 and 1630 kHz, there is a dashed line indicating a transition. From 1630 to 11 040 kHz, it is flat at -90 dBm/Hz peak, with a note about -50 dBm power in any 1 MHz sliding window above 1630 kHz. + +| Frequency band $f$ (kHz) | Equation for line (dBm/Hz) | +|-------------------------------|------------------------------------------------------------------------------------------------------------------------| +| $0 < f < 50(70)$ | -90 | +| $> f_1 = 50(70) < f < 80(90)$ | $-90 + 12 \times \log_2(f/f_1)$ | +| $80(90) < f < 138$ | Note 2 | +| $138 < f < 276$ | -34.5 | +| $276 < f < 614$ | $-34.5 - 48 \times \log_2(f/276)$ | +| $614 < f < 1221$ | -90 | +| $1221 < f < 1630$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of $(-90 - 48 \times \log_2(f/1221) + 60) \text{ dBm}$ | +| $1630 < f < 11\ 040$ | -90 peak, with max power in the $[f, f + 1 \text{ MHz}]$ window of -50 dBm | + +NOTE 1 – 50 and 80 kHz are frequency limits referring to ADSL over ISDN lines operating with 2B1Q code (G.961 Appendix II). 70 and 90 kHz are frequency limits referring to ADSL over ISDN lines operating with 4B3T code (G.961 Appendix I). + +NOTE 2 – The value of PSD in this region depends on the low-pass and high-pass filter designs. The filters affect the ISDN-BA performance when combined with ADSL in two ways: + +- 1) the residual ADSL power, filtered by the high pass and received by the ISDN-BA receiver as noise; +- 2) the amplitude and phase distortion introduced by low-pass filters. + +It is expected that the degradation impact on the ISDN-BA line system performance be not more than 4.5 dB and 4 dB, for 2B1Q and 4B3T line codes respectively, at the insertion loss reference frequency. + +**Figure B.4/G.992.1 – ATU-R transmitter PSD mask** + +The maximum level of the PSD of the ADSL signal measured at the ISDN port of the splitter shall not exceed the limits defined in the first two rows of the table in Figure B.4. + +All PSD measurements made at the Line port of the ISDN splitter shall use a 100 $\Omega$ resistive reference impedance. + +All PSD measurements made at the ISDN port of the ISDN splitter shall use the design impedance of ISDN-BA for 2B1Q and 4B3T respectively as defined in ETSI TS 102 080 (V1.3.1). + +### B.2.2.1 Passband PSD and response + +The average PSD within the used passband shall be no greater than $-38$ dBm/Hz; the upper end of this passband depends on whether the signal is for initialization (see B.2.2.3.1) or steady state (see B.2.2.3.2). + +The passband ripple shall be no greater than $+3.5$ dB; the maximum PSD of $-34.5$ dBm/Hz applies across the whole band from $138$ kHz to $276$ kHz. + +The group delay variation over the passband shall not exceed $50$ $\mu\text{s}$ . + +### B.2.2.2 Stop-band PSDs + +See Figure B.4. + +### B.2.2.3 Transmit power spectral density and Nominal aggregate power level + +There are two different PSD masks for the ATU-R transmit signal, depending on the type of signal sent. In all cases the power in the voiceband measured at the U-R interface and that is delivered to the ISDN interface shall conform to the specification in Figure B.4. + +#### B.2.2.3.1 All initialization signals starting with R-REVERB1 + +The nominal PSD in the band from $138$ to $276$ kHz shall be $-38$ dBm/Hz for an aggregate power of not greater than $13.3$ dBm. + +The nominal aggregate power level shall be $13.26$ dBm. + +During the R-REVERB and R-SEGUE signals, all subcarriers from index $i$ to $63$ shall be transmitted, with $i$ vendor discretionary. However, at the vendor's discretion, one or more of these subcarriers may not be transmitted during the R-MEDLEY signal. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than $1$ dB above the nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-37$ dBm/Hz. + +#### B.2.2.3.2 Steady-state data signal + +The nominal PSD in the band from $138$ to $276$ kHz shall be set at $-38$ dBm/Hz. The nominal aggregate power shall be set at $-1.65 + 10\log(ncup)$ dBm, where $ncup$ is the number of subcarriers used (i.e. with $b_i > 0$ ) ( $13.3$ dBm if all subcarriers are used). The transmit PSD and aggregate power may, however, be changed from their nominal values in either of the following circumstances: + +- The bits and gains table (received from the ATU-C during initialization and possibly updated through bit swaps, see C-B&G in 10.8.13 and 11.2) may not allocate bits to some subcarriers and may finely adjust (i.e. within the range $-14.5$ to $+2.5$ dBm) the transmit PSD level of others in order to equalize expected error rates on each of those subcarriers. +- Vendor discretionary transmit PSD levels for unused subcarriers (i.e. $b_i = 0$ ). The maximum transmit PSD for these subcarriers is specified in b) and c) below. + +To allow for non-ideal transmit filter effects (e.g. passband ripple and transition band rolloff), the maximum transmit PSD shall be no more than $1$ dB above the finely adjusted nominal PSD level. The maximum transmit PSD shall therefore be no higher than $-34.5$ dBm/Hz. + +The transmit PSD of each subcarrier is defined as follows: + +- For the subcarriers with ( $b_i > 0$ ), the ATU-R transmitter shall transmit at PSD levels equal to those specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at R-MEDLEY transmit PSD level). The aggregate transmit power in these subcarriers shall not exceed $-1.65 + 10\log(ncup_1)$ dBm by more than $0.7$ dB, where $ncup_1$ is the number of these subcarriers (i.e. with $b_i > 0$ ). + +- b) For the subcarriers with ( $b_i = 0$ and $g_i > 0$ ), the ATU-R transmitter should and is recommended to transmit at PSD levels equal to those specified by the $g_i$ (e.g. $g_i = 1$ , then transmit at R-MEDLEY level), with a 4-QAM constellation point (which may change from symbol to symbol). The ATU-C receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers shall be no higher than the R-REVERB1 transmit PSD level + $10\log(g_i^2)$ dB. The aggregate transmit power in these subcarriers shall not exceed $-1.65 + 10\log(ncup_2)$ dBm, where $ncup_2$ is the number of these subcarriers (i.e. with $b_i = 0$ and $g_i > 0$ ). +- c) For the subcarriers with ( $b_i = 0$ and $g_i = 0$ ), the ATU-R transmitter should and is recommended to transmit no power on those subcarriers. The ATU-C receiver cannot assume any particular PSD levels on those subcarriers. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +The aggregate transmit power over the 138 to 276 kHz band shall be no higher than 13.3 dBm, which is equivalent to an average transmit PSD of no higher than $-38$ dBm/Hz. + +It is recommended that the $g_i$ values for subcarriers with $g_i > 0$ are constraint within $\pm 2.5$ dB with respect to $g_{sync}$ , during initialization and subsequent bit swaps, to avoid cyclostationary interference from the synchronization symbol. + +### B.2.2.3.3 Synchronization symbol + +At initialization time, the sync symbol reference transmit PSD level shall be set at $-38 + 10\log(g_{sync}^2)$ dBm/Hz, with $g_{sync}^2$ defined as the average $g_i^2$ value over the used (i.e. $b_i > 0$ ) subcarriers. The sync symbol reference transmit PSD shall not be updated with used subcarrier gain changes during SHOWTIME. + +The transmit PSD level for those subcarriers with $g_i > 0$ shall be the sync symbol reference transmit PSD level. The transmit PSD levels of those subcarriers with $g_i = 0$ shall be at least 10 dB below the sync symbol reference transmit PSD level if the subcarrier is below the lowest used subcarrier (lowest $i$ with $b_i > 0$ ) and shall be below the sync symbol reference transmit PSD level if the subcarrier is above the lowest used subcarrier. + +Since the $g_i$ are applied only to the data symbols, the transmit PSD of a synchronization symbol differs from the transmit PSD of a data symbol. These $g_i$ are calculated for the multipoint constellations in order to equalize the expected error rate on all subcarriers, and are therefore irrelevant for most of the 4-QAM modulated subcarriers of the synchronization symbol. + +### B.2.3 Data subcarriers (replaces 8.11.1.1) + +The channel analysis signal (R-REVERB1) defined in B.3.7 allows for a maximum of 63 carriers, however the use of carriers between $n = 1$ to 32 is optional and their use is negotiated through G.994.1 (see B.3.1 and B.3.2). This lower limit on $n$ is partly determined by the ISDN/ADSL splitting filters. If FDM is used to separate the upstream and downstream ADSL signals, the upper limit is set by down-up splitting filters. The cut-off frequencies of these filters are completely at the discretion of the manufacturer, and the range of usable $n$ is determined during the channel estimation. + +#### B.2.4 Pilot frequency + +There is no upstream pilot, the ATU-R shall perform slave loop timing based on the downstream pilot. + +#### B.2.5 Nyquist frequency (supplements 8.11.1.2) + +The upstream Nyquist frequency shall be at subcarrier #64 ( $f = 276$ kHz). + +#### B.2.6 Modulation by the Inverse Discrete Fourier Transform (replaces 8.11.2) + +The modulating transform defines the relationship between the 128 real values $x_k$ and the $Z_i$ : + +$$x_k = \sum_{i=0}^{127} \exp\left(\frac{j\pi k i}{64}\right) Z_i \quad \text{for } k = 0 \text{ to } 127$$ + +The encoder and scaler generate complex values of $Z_i$ corresponding to tones 1 to 63 (plus zero at DC and one real value if the Nyquist frequency is used). In order to generate real values of $x_k$ , these values shall be augmented so that the vector $Z_i$ has Hermitian symmetry. That is, + +$$Z_i = \text{conj}[Z_{128-i}] \quad \text{for } i = 65 \text{ to } 128$$ + +If the carriers $N = 1$ to 32 are not used, then: + +$$Z_i = 0 \quad \text{for } i = 1 \text{ to } 32$$ + +NOTE – For the mirrored complex conjugate transmitter, + +$$Z_i = \text{conj}[Z_{64-i}] \quad \text{for } i = 1 \text{ to } 31$$ + +$$Z_{32} = 0$$ + +#### B.2.7 Synchronization symbol (supplements 8.11.3) + +The data pattern used in the synchronization symbol shall be the pseudo-random sequence PRU ( $d_n$ , for $n = 1$ to 128), defined by: + +$$d_n = 1 \quad \text{for } n = 1 \text{ to } 6$$ + +$$d_n = d_{n-5} \oplus d_{n-6} \quad \text{for } n = 7 \text{ to } 128$$ + +The bits are used as follows: the first pair of bits ( $d_1$ and $d_2$ ) is used for the DC and Nyquist subcarriers (the power assigned to them is zero, so the bits are effectively ignored); then the first and second bits of subsequent pairs shall be used to define the $X_i$ and $Y_i$ for $i = 1$ to 63 in accordance to Table 7-13. + +#### B.2.8 Cyclic prefix (replaces 8.12) + +The cyclic prefix shall be used for all symbols beginning with segment C-REVERB3 of the initialization sequence, as defined in 10.7.2. + +The last 8 samples of the output of the IDFT ( $x_k$ for $k = 120$ to 127) shall be prepended to the block of 64 samples and read out to the DAC in sequence. That is, the subscript, $k$ , of the DAC samples in sequence are 120...127, 0...127. + +### **B.3 Initialization (see clause 10)** + +#### **B.3.1 Handshake – ATU-C (supplements 10.2)** + +##### **B.3.1.1 CL messages (supplements 10.2.1)** + +See Table B.1. + +**Table B.1/G.992.1 – ATU-C CL message NPar(2) bit definitions for Annex B** + +| NPar(2) bit | Definition | +|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Tones 1 to 32 | If set to ONE, signifies that the ATU-C is capable of receiving upstream tones 1 to 32 during transceiver training (only applicable for G.992.1 Annex B). | + +##### **B.3.1.2 MS messages (supplements 10.2.2)** + +See Table B.2. + +**Table B.2/G.992.1 – ATU-C MS message NPar(2) bit definitions for Annex B** + +| NPar(2) bit | Definition | +|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------| +| Tones 1 to 32 | Signifies that the ATU-R is allowed to transmit upstream tones 1 to 32 during transceiver training (only applicable for G.992.1 Annex B). | + +#### **B.3.2 Handshake – ATU-R (supplements 10.3)** + +##### **B.3.2.1 CLR messages (supplements 10.3.1)** + +See Table B.3. + +**Table B.3/G.992.1 – ATU-R CLR message NPar(2) bit definitions for Annex B** + +| NPar(2) bit | Definition | +|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Tones 1 to 32 | If set to ONE, signifies that the ATU-R is capable of transmitting upstream tones 1 to 32 during transceiver training (only applicable for G.992.1 Annex B). | + +##### **B.3.2.2 MS messages (supplements 10.3.2)** + +See Table B.4. + +**Table B.4/G.992.1 – ATU-R MS message NPar(2) bit definitions for Annex B** + +| NPar(2) bit | Definition | +|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Tones 1 to 32 | Set to ONE if and only if this bit was set to ONE in both the last previous CL message and the last previous CLR message. Signifies that the ATU-R is allowed to transmit upstream tones 1 to 32 (or a subset thereof) during transceiver training (only applicable for G.992.1 Annex B). | + +### B.3.3 Power Cut-back (supplements 10.4.5.1) + +If the total upstream power measured on 12 consecutive subcarriers in the range 36 to 51 during R-REVERB1 is greater than 3 dBm, then the PSD for C-REVERB1 and all subsequent downstream signals shall be as shown in Table B.5. + +The ATU-C shall choose 12 consecutive subcarriers in the range 36 to 51 actually transmitted at nominal power by the ATU-R. In the case where the ATU-C cannot find 12 such subcarriers, the ATU-C is allowed to use less subcarriers in the upstream power measurement, but shall compensate the measurement accordingly. + +**Table B.5/G.992.1 – Power cut-back: downstream PSD as a function of upstream received power** + +| | | | | | | | | +|---------------------------------|-----|-----|-----|-----|-----|-----|-----| +| Upstream received power (dBm) < | 0 | 1.5 | 3 | 4.5 | 6 | 7.5 | 9 | +| Max downstream PSD (dBm/Hz) | -40 | -42 | -44 | -46 | -48 | -50 | -52 | + +This chosen level shall become the reference level for all subsequent gain calculations. + +### B.3.4 Estimated average upstream loop attenuation (see 10.8.9.1) + +With the allowable transmit PSDs -38 dBm/Hz over the 138 to 276 kHz band, the total transmit power, as used for this calculation, shall be 13.3 dBm. + +### B.3.5 Estimated average downstream loop attenuation (10.9.8.1) + +With the allowable transmit PSDs as defined in Table B.5 (-40 dBm/Hz to -52 dBm/Hz) over the 138 to 1104 kHz band, the total transmit power, as used for this calculation, may range from a maximum of 19.9 dBm in steps of -2 dB to a minimum of 7.9 dBm. + +### B.3.6 C-PILOT1 (for 10.4.3) + +$f_{\text{C-PILOT1}} = 414$ kHz that is, $n_{\text{C-PILOT1}} = 96$ . + +### B.3.7 R-REVERB1 (supplements 10.5.2) + +The data pattern used in R-REVERB1 shall be the pseudo-random sequence PRU ( $d_n$ , for $n = 1$ to 128), defined by: + +$$d_n = 1 \quad \text{for } n = 1 \text{ to } 6$$ + +$$d_n = d_{n-5} \oplus d_{n-6} \quad \text{for } n = 7 \text{ to } 128$$ + +The bits are used as follows: the first pair of bits ( $d_1$ and $d_2$ ) is used for the DC and Nyquist subcarriers (the power assigned to them is, of course, zero, so the bits are effectively ignored); then the first and second bits of subsequent pairs shall be used to define the $X_i$ and $Y_i$ for $i = 1$ to 63 as defined for C-REVERB1 (see 10.4.5). + +NOTE – The $d_1$ to $d_6$ are re-initialized for each symbol, so each symbol of R-REVERB1 uses the same data. + +### **B.3.8 R-MEDLEY (replaces 10.7.8)** + +R-MEDLEY is a wideband pseudo-random signal used for estimation of the upstream SNR at the ATU-C. The data to be transmitted are derived from the pseudo-random sequence PRU defined in 10.5.2 (R-REVERB1). In contrast to R-REVERB1, however, the cyclic prefix is used and the data sequence continue from one symbol to the next. Because the sequence is of length 63, and 128 bits are used for each symbol, the subcarrier vector for R-MEDLEY changes from one symbol to the next. R-MEDLEY is transmitted for 16 384 symbol periods. Following R-MEDLEY, the ATU-R enters signalling state R-REVERB4. + +### **B.3.9 C-MSG2 (supplements 10.8.9)** + +$$n_{\text{C-MSG1}} = 75$$ + +$$n_{\text{C-MSG2}} = 91$$ + +### **B.3.10 R-MSG2 (supplements 10.9.8)** + +$$N_{\text{R-MSG1}} = 44$$ + +$$N_{\text{R-MSG2}} = 49$$ + +### **B.3.11 C-ECT and R-ECT (supplements 10.4.7 and 10.5.4)** + +Because C-ECT and R-ECT are vendor defined signals (see 10.4.7 and 10.5.4) the PSD specification shall be interpreted only as a maximum. This maximum level is $-39 - 2n_{\text{PCB}}$ (for C-ECT) and $-37$ (for R-ECT) dBm/Hz (with $n$ indicating the power cut-back, $n = 0$ to $6$ ) for the band from 138 kHz to 1104 kHz (for C-ECT) and to 276 (for R-ECT). Subcarriers 1 to 31 may be used, but the power in the ISDN band shall conform to the specification given in B.1.3 and B.2.2. + +### **B.3.12 C-B&G (replaces 10.8.13)** + +C-B&G shall be used to transmit to the ATU-R the bits and gains information, {i.e. $b_1, g_1, b_2, g_2, \dots, b_{63}, g_{63}$ } that are to be used on the upstream carriers. $b_i$ indicates the number of bits to be coded by the ATU-R transmitter onto the $i$ th upstream carrier; $g_i$ indicates the scale factor, relative to the gain that was used for that carrier during the transmission of R-MEDLEY, that shall be applied to the $i$ th upstream carrier. Because no bits or energy shall be transmitted at DC or one-half the sampling rate, $b_0, g_0, b_{64}$ , and $g_{64}$ shall all be presumed to be zero and shall not be transmitted. + +Each $b_i$ shall be represented as an unsigned 4-bit integer, with valid $b_i$ s lying in the range of zero to $N_{\text{upmax}}$ , the maximum number of bits that the ATU-R is prepared to modulate onto any subcarrier, which is communicated in R-MSG1. + +Each $g_i$ shall be represented as an unsigned 12-bit fixed-point quantity, with the binary point assumed just to the right of the third most significant bit. For example, a $g_i$ with binary representation (most significant bit listed first) $001.010000000_2$ would instruct the ATU-R to scale the constellation for carrier $i$ , by a gain factor of 1.25, so that the power in that carrier shall be 1.94 dB higher than it was during R-MEDLEY. + +For subcarriers on which no data are to be transmitted, and the receiver will never allocate bits (e.g. out-of-band subcarriers) both $b_i$ and $g_i$ shall be set to zero ( $0000$ and $00000000\ 0000$ , respectively). For subcarriers on which no data are to be currently transmitted, but the receiver may allocate bits later (e.g. as a result of an SNR improvement), the $b_i$ shall be set to zero and the $g_i$ a value in the 0.19 to 1.33 range ( $000.001100000_2$ to $001.010101011_2$ ). + +The C-B&G information shall be mapped in a 1008-bit (126 byte) message $m$ defined by: + +$$m = \{m_{1007}, m_{1006}, \dots, m_1, m_0\} = \{g_{63}, b_{63}, \dots, g_1, b_1\}$$ + +with the MSB of $b_i$ and $g_i$ in the higher $m$ index and $m_0$ being transmitted first. The message $m$ shall be transmitted in 126 symbols, using the transmission method as described 10.8.9. + +Following C-B&G, the ATU-C shall enter the state C-CRC5. The new timing diagram of the initialization sequence (part 2) (modified from the diagram given in 10.9.18) is shown in Figure B.5. + +![Timing diagram of the initialization sequence - Part 2. The diagram shows a sequence of commands and responses between a controller (left) and a device (right). The sequence includes C-REVERB4, C-SEGUE2, C-RATES-RA/C-CRC-RA1, C-MSG-RA/C-CRC-RA2, C-REVERB-RA, C-SEGUE-RA, C-MSG2/C-CRC3, C-RATES2/C-CRC4, C-B&G/C-CRC5, C-REVERB5, C-SEGUE3, and SHOWTIME. Responses include R-MEDLEY, R-REVERB4, R-SEGUE3, R-MSG-RA/R-CRC-RA1, R-RATES-RA/R-CRC-RA2, R-REVERB-RA, R-SEGUE-RA, R-MSG2/R-CRC-3, R-RATES2/R-CRC4, R-REVERB5, R-SEGUE4, R-B&G/R-CRC5, R-REVERB6, R-SEGUE5, and SHOWTIME. Timing constraints are indicated by arrows and numerical values.](40d0aaaa3afa0a9fabe637941ca250bb_img.jpg) + +| | | | | | +|---------------------------|--------------------------------------------|------------------------------------------------|--------------------------------------------|---------------------------| +| $\geq 727$
$\leq 6000$ | C-REVERB4 | | R-MEDLEY | | +| | | | R-REVERB4 | 128 | +| | | | R-SEGUE3 | 10 | +| | | | R-MSG-RA/R-CRC-RA1
R-RATES-RA/R-CRC-RA2 | 15 | +| | | $\geq 80$
$\leq 2413$ | | | +| 10 | C-SEGUE2 | | | | +| 130 | C-RATES-RA/C-CRC-RA1
C-MSG-RA/C-CRC-RA2 | | R-REVERB-RA | $\geq 288$
$\leq 4000$ | +| | | $\geq 64$
$\leq 1447$ | | | +| $\geq 163$
$\leq 4000$ | C-REVERB-RA | | R-SEGUE-RA | 10 | +| | | | R-MSG2/R-CRC-3
R-RATES2/R-CRC4 | 9 | +| | | | | | +| | | | | | +| | | $\geq 80$
$\leq 2534$ | | | +| 10 | C-SEGUE-RA | | | | +| 9 | C-MSG2/C-CRC3
C-RATES2/C-CRC4 | | R-REVERB5 | $\geq 291$
$\leq 4000$ | +| 128 | C-B&G/C-CRC5 | | | | +| | | $\geq 64$
$\leq 1319$ | | | +| $\geq 586$
$\leq 4000$ | C-REVERB5 | | R-SEGUE4 | 10 | +| | | | R-B&G/R-CRC5 | 512 | +| | | | | | +| | | | | | +| | | $\leq 2095$ | | | +| 10 | C-SEGUE3 | | | | +| | | $\leq 1895$ | | | +| | | | R-SEGUE5 | 10 | +| | SHOWTIME | Maximum
initialization time
11.3 seconds | SHOWTIME | | + +T1532750-99 + +Timing diagram of the initialization sequence - Part 2. The diagram shows a sequence of commands and responses between a controller (left) and a device (right). The sequence includes C-REVERB4, C-SEGUE2, C-RATES-RA/C-CRC-RA1, C-MSG-RA/C-CRC-RA2, C-REVERB-RA, C-SEGUE-RA, C-MSG2/C-CRC3, C-RATES2/C-CRC4, C-B&G/C-CRC5, C-REVERB5, C-SEGUE3, and SHOWTIME. Responses include R-MEDLEY, R-REVERB4, R-SEGUE3, R-MSG-RA/R-CRC-RA1, R-RATES-RA/R-CRC-RA2, R-REVERB-RA, R-SEGUE-RA, R-MSG2/R-CRC-3, R-RATES2/R-CRC4, R-REVERB5, R-SEGUE4, R-B&G/R-CRC5, R-REVERB6, R-SEGUE5, and SHOWTIME. Timing constraints are indicated by arrows and numerical values. + +Figure B.5/G.992.1 – Timing diagram of the initialization sequence – Part 2 + +**Specific requirements for an ADSL system operating in the same cable as ISDN +as defined in ITU-T Recommendation G.961 Appendix III** + +### C.1 Scope + +This annex describes those specifications that are unique to an ADSL system coexisting in the same binder as TCM-ISDN as defined Recommendation G.961 Appendix III. The subclauses in this annex provide supplementary and replacement material to the clauses in the main body. The nature of the material is parenthetically indicated in the subclause heading. The modifications described in this annex allow a performance improvement from the ADSL system specified in Annex A in an environment coexisting with TCM-ISDN in the same cable. This annex also defines those parameters of this ADSL system that have been left undefined in the main body of this Recommendation. It is recommended that ADSL system implementing Annex C also implements Annex A. + +### C.2 Definitions + +| | | +|----------------------------|----------------------------------------------------------------------------------------------------| +| Bitmap-F C | ATU-R transmitter bitmap under TCM-ISDN FEXT noise generated at ATU-C | +| Bitmap-F R | ATU-C transmitter bitmap under TCM-ISDN FEXT noise generated at ATU-R | +| Bitmap-N C | ATU-R transmitter bitmap under TCM-ISDN NEXT noise generated at ATU-C | +| Bitmap-N R | ATU-C transmitter bitmap under TCM-ISDN NEXT noise generated at ATU-R | +| Dual Bitmap | The Dual Bitmap method has dual bit rates under the FEXT and NEXT noise from TCM-ISDN | +| FEXT Bitmap | Similar to the Dual Bitmap method however transmission only occurs during FEXT noise from TCM-ISDN | +| FEXT C duration | TCM-ISDN FEXT duration at ATU-C estimated by the ATU-R | +| FEXT C symbol | DMT symbol transmitted by ATU-R during TCM-ISDN FEXT | +| FEXT R duration | TCM-ISDN FEXT duration at ATU-R estimated by the ATU-C | +| FEXT R symbol | DMT symbol transmitted by ATU-C during TCM-ISDN FEXT | +| Hyperframe | 5 Superframes structure which synchronized TTR | +| NEXT C duration | TCM-ISDN NEXT duration at ATU-C estimated by the ATU-R | +| NEXT C symbol | DMT symbol transmitted by ATU-R during TCM-ISDN NEXT | +| NEXT R duration | TCM-ISDN NEXT duration at ATU-R estimated by the ATU-C | +| NEXT R symbol | DMT symbol transmitted by ATU-C during TCM-ISDN NEXT | +| N SWF | Sliding Window frame counter | +| Subframe | 10 consecutive DMT symbols (except for sync symbols) according to TTR timing | +| TTR | TCM-ISDN Timing Reference | +| TTR C | Timing reference used in ATU-C | + +TTRR Timing reference used in ATU-R + +UI Unit Interval + +### C.3 Reference Models + +#### C.3.1 ATU-C transmitter reference model (replaces figures in 5.1) + +See Figures C.1 and C.2. + +![Block diagram of the ATU-C transmitter reference model for STM transport. The diagram shows the signal flow from multiple input sources (AS0-AS3, LS0-LS2, NTR, OAM, EOC/AOC, TTR) through a Mux/Sync Control block. The data is then split into two paths: one for 'Bits' (AS0-AS3, LS0-LS2, NTR) and one for 'Bits' & 'Gains' (OAM, EOC/AOC). The 'Bits' path goes through a CRC block (crc_f), scrambling and FEC, and a rate converter. The 'Bits' & 'Gains' path goes through a CRC block (crc_i), scrambling and FEC, an interleaver, and a rate converter. Both paths then enter a Tone ordering block. The output of the Tone ordering block is fed into a Constellation encoder and gain scaling block, which also receives 'Bits' and 'Bits' & 'Gains' as inputs. The output of the Constellation encoder is then processed by an IDFT block. The IDFT output is split into two paths: one for 'Bits' (indices 511, 510, 480, 1, n=0) and one for 'Bits' & 'Gains' (indices i=1 to 255). Both paths then enter an Output Parallel/Serial Buffer. The output of the buffer is processed by a DAC and Analogue processing block. Reference points V-C, A, B, C, and U-C are marked along the bottom of the diagram. A note at the bottom right indicates the diagram is T1532760-99.](2df1e34671c73d7c0d047d4e9009251e_img.jpg) + +The diagram illustrates the ATU-C transmitter reference model for STM transport. It shows the flow of data from various input sources through a series of processing blocks. The inputs include AS0, AS1, AS2, AS3, LS0, LS1, LS2, NTR, OAM, EOC/AOC, and TTR. These are processed through a Mux/Sync Control block. The data is then split into two paths: one for 'Bits' (AS0, AS1, AS2, AS3, LS0, LS1, LS2, NTR) and one for 'Bits' & 'Gains' (OAM, EOC/AOC). The 'Bits' path goes through a CRC block (crcf), scrambling and FEC, and a rate converter. The 'Bits' & 'Gains' path goes through a CRC block (crci), scrambling and FEC, an interleaver, and a rate converter. Both paths then enter a Tone ordering block. The output of the Tone ordering block is fed into a Constellation encoder and gain scaling block, which also receives 'Bits' and 'Bits' & 'Gains' as inputs. The output of the Constellation encoder is then processed by an IDFT block. The IDFT output is split into two paths: one for 'Bits' (indices 511, 510, 480, 1, n=0) and one for 'Bits' & 'Gains' (indices i=1 to 255). Both paths then enter an Output Parallel/Serial Buffer. The output of the buffer is processed by a DAC and Analogue processing block. Reference points V-C, A, B, C, and U-C are marked along the bottom of the diagram. A note at the bottom right indicates the diagram is T1532760-99. + +Block diagram of the ATU-C transmitter reference model for STM transport. The diagram shows the signal flow from multiple input sources (AS0-AS3, LS0-LS2, NTR, OAM, EOC/AOC, TTR) through a Mux/Sync Control block. The data is then split into two paths: one for 'Bits' (AS0-AS3, LS0-LS2, NTR) and one for 'Bits' & 'Gains' (OAM, EOC/AOC). The 'Bits' path goes through a CRC block (crc\_f), scrambling and FEC, and a rate converter. The 'Bits' & 'Gains' path goes through a CRC block (crc\_i), scrambling and FEC, an interleaver, and a rate converter. Both paths then enter a Tone ordering block. The output of the Tone ordering block is fed into a Constellation encoder and gain scaling block, which also receives 'Bits' and 'Bits' & 'Gains' as inputs. The output of the Constellation encoder is then processed by an IDFT block. The IDFT output is split into two paths: one for 'Bits' (indices 511, 510, 480, 1, n=0) and one for 'Bits' & 'Gains' (indices i=1 to 255). Both paths then enter an Output Parallel/Serial Buffer. The output of the buffer is processed by a DAC and Analogue processing block. Reference points V-C, A, B, C, and U-C are marked along the bottom of the diagram. A note at the bottom right indicates the diagram is T1532760-99. + +NOTE – The TTR may be generated in ATU-C without being provided from the TCM-ISDN clock. + +**Figure C.1/G.992.1 – ATU-C transmitter reference model for STM transport** + +![Block diagram of the ATU-C transmitter reference model for ATM transport. The diagram shows the flow of data from ATM0, ATM1, and NTR inputs through various processing stages including Cell TC, Mux/Sync Control, CRC, scrambling, FEC, interleaving, rate conversion, tone ordering, constellation encoding, IDFT, and finally to a DAC and Analogue processing. Reference points V-C, A, B, C, and U-C are marked along the signal path.](130e5cca4d4856272e57a0247d14e094_img.jpg) + +The diagram illustrates the ATU-C transmitter reference model for ATM transport. It shows the following components and signal flow: + +- Inputs:** ATM0, ATM1, NTR, OAM, EOC/AOC ib, and TTR. +- Processing Stages:** + - ATM0 and ATM1 pass through **Cell TC** (AS0 and AS1 respectively) to a **Mux/Sync Control** block. + - NTR also feeds into the **Mux/Sync Control** block. + - The **Mux/Sync Control** block outputs to two parallel paths: + - One path goes through **crcf**, **scram & FEC**, and a **Rate converter**. + - The other path goes through **crci**, **scram & FEC**, an **Inter-leaver**, and a **Rate converter**. + - Both **Rate converter** outputs feed into a **Tone ordering** block. + - The **Tone ordering** block also receives **"Bits"** as input. + - The output of the **Tone ordering** block feeds into a **Constellation encoder and gain scaling** block. + - This block also receives **"Bits" & "Gains"** as input. + - The output of the **Constellation encoder and gain scaling** block feeds into an **IDFT** block. + - The **IDFT** block outputs are labeled 511, 510, 480, 1, and n=0. + - These outputs feed into an **Output Parallel/Serial Buffer** block. + - The **Output Parallel/Serial Buffer** block feeds into a **DAC and Analogue processing** block, which produces the final output. +- Reference Points:** + - V-C**: Located at the input of the **Cell TC** blocks. + - A**: Located at the output of the **Mux/Sync Control** block, labeled **Mux Data Frame**. + - B**: Located at the output of the **scram & FEC** blocks, labeled **FEC Output Data Frame**. + - C**: Located at the output of the **Tone ordering** block, labeled **Constellation Encoder Input Data Frame**. + - U-C**: Located at the output of the **DAC and Analogue processing** block. +- Other Labels:** + - Zi** for i=1 to 255 is shown near the IDFT block. + - The identifier **T1532770-99** is located at the bottom right of the diagram. + +Block diagram of the ATU-C transmitter reference model for ATM transport. The diagram shows the flow of data from ATM0, ATM1, and NTR inputs through various processing stages including Cell TC, Mux/Sync Control, CRC, scrambling, FEC, interleaving, rate conversion, tone ordering, constellation encoding, IDFT, and finally to a DAC and Analogue processing. Reference points V-C, A, B, C, and U-C are marked along the signal path. + +NOTE – The TTR may be generated in ATU-C without being provided from the TCM-ISDN clock. + +**Figure C.2/G.992.1 – ATU-C transmitter reference model for ATM transport** + +### C.3.2 ATU-R transmitter reference model (replaces figures in 5.2) + +See Figures C.3 and C.4. + +![Block diagram of the ATU-R transmitter reference model for STM transport. The diagram shows the signal flow from input LS0, LS1, and LS2 through various processing stages including Mux/Sync Control, CRC, scrambling, FEC, rate conversion, tone ordering, constellation encoding, IDFT, and finally to the DAC and Analogue processing. Reference points A, B, C, and U-R are marked along the signal path. A TTR_R signal is also shown as an input to the rate converters.](10f4e3a2f3c016555ee12a5b556ba834_img.jpg) + +The diagram illustrates the ATU-R transmitter reference model for STM transport. The signal flow is as follows: + +- Inputs:** LS0, LS1, LS2, and EOC/AOC. +- Mux/Sync Control:** Receives LS0, LS1, LS2, and EOC/AOC. It outputs two signals to **crcf** and **crcl** blocks. +- crcf and crcl blocks:** Process the signals from the Mux/Sync Control. The output of **crcf** goes to a **scrambler & FEC** block. The output of **crcl** goes to a **scrambler & FEC** block, which then goes to an **Inter-leaver** block. +- Rate converter:** Both **scrambler & FEC** blocks output to a **Rate converter** block. The **Rate converter** block also receives a **TTRR** signal. +- Tone ordering:** The output of the **Rate converter** block goes to the **Tone ordering** block. The **Tone ordering** block also receives "Bits" and "Bits" & "Gains" inputs. +- Constellation encoder and gain scaling:** The output of the **Tone ordering** block goes to the **Constellation encoder and gain scaling** block. This block also receives "Bits" and "Bits" & "Gains" inputs. +- IDFT:** The output of the **Constellation encoder and gain scaling** block goes to the **IDFT** block. The **IDFT** block also receives $Z_i$ inputs for $i=1$ to 31. +- Output Parallel/Serial Buffer:** The output of the **IDFT** block goes to the **Output Parallel/Serial Buffer** block. The **Output Parallel/Serial Buffer** block also receives inputs from the **DAC and Analogue processing** block. +- DAC and Analogue processing:** This block receives inputs from the **Output Parallel/Serial Buffer** block and outputs to the **U-R** output. +- Reference Points:** + - A:** Mux Data Frame (between Mux/Sync Control and crcf/crcl blocks). + - B:** FEC Output Data Frame (between scrambler & FEC and Rate converter blocks). + - C:** Constellation Encoder Input Data Frame (between Tone ordering and Constellation encoder and gain scaling blocks). + - U-R:** Output reference point (at the output of the DAC and Analogue processing block). + +Block diagram of the ATU-R transmitter reference model for STM transport. The diagram shows the signal flow from input LS0, LS1, and LS2 through various processing stages including Mux/Sync Control, CRC, scrambling, FEC, rate conversion, tone ordering, constellation encoding, IDFT, and finally to the DAC and Analogue processing. Reference points A, B, C, and U-R are marked along the signal path. A TTR\_R signal is also shown as an input to the rate converters. + +NOTE – The $TTR_R$ shall be generated in ATU-R from the received $TTR_C$ signal, and it is locked to 690 periods of upstream sampling clock (276 kHz). + +Figure C.3/G.992.1 – ATU-R transmitter reference model for STM transport + +![Block diagram of ATU-R transmitter reference model for ATM transport. The diagram shows two input paths, ATM0 and ATM1, each passing through a Cell TC (LS0 and LS1 respectively). These are then multiplexed by a Mux/Sync Control block, which also receives EOC/AOC input. The output of the mux goes to two parallel processing paths. The top path consists of a crcf block, a scrambler & FEC block, and a Rate converter. The bottom path consists of a crci block, a scrambler & FEC block, an Inter-leaver, and a Rate converter. Both Rate converters output to a Tone ordering block. The Tone ordering block also receives 'Bits' and 'TTRR' inputs. Its output goes to a Constellation encoder and gain scaling block, which also receives 'Bits' & 'Gains' and Zi (i=1 to 31) inputs. The output of the constellation encoder goes to an IDFT block. The IDFT block has 64 outputs, numbered 63, 62, 59, 1, and n=0, which are then processed by an Output Parallel/Serial Buffer. The buffer output goes to a DAC and Analogue processing block, which finally outputs to the U-R. Reference points T-R, A, B, C, and U-R are marked along the bottom. T-R is at the input, A is at the Mux Data Frame, B is at the FEC Output Data Frame, C is at the Constellation Encoder Input Data Frame, and U-R is at the final output. A reference point Zi is also marked between C and U-R. The diagram is labeled T1532790-99 at the bottom right.](aa757e4ac9b0e12f51a06396c4e86b52_img.jpg) + +Block diagram of ATU-R transmitter reference model for ATM transport. The diagram shows two input paths, ATM0 and ATM1, each passing through a Cell TC (LS0 and LS1 respectively). These are then multiplexed by a Mux/Sync Control block, which also receives EOC/AOC input. The output of the mux goes to two parallel processing paths. The top path consists of a crcf block, a scrambler & FEC block, and a Rate converter. The bottom path consists of a crci block, a scrambler & FEC block, an Inter-leaver, and a Rate converter. Both Rate converters output to a Tone ordering block. The Tone ordering block also receives 'Bits' and 'TTRR' inputs. Its output goes to a Constellation encoder and gain scaling block, which also receives 'Bits' & 'Gains' and Zi (i=1 to 31) inputs. The output of the constellation encoder goes to an IDFT block. The IDFT block has 64 outputs, numbered 63, 62, 59, 1, and n=0, which are then processed by an Output Parallel/Serial Buffer. The buffer output goes to a DAC and Analogue processing block, which finally outputs to the U-R. Reference points T-R, A, B, C, and U-R are marked along the bottom. T-R is at the input, A is at the Mux Data Frame, B is at the FEC Output Data Frame, C is at the Constellation Encoder Input Data Frame, and U-R is at the final output. A reference point Zi is also marked between C and U-R. The diagram is labeled T1532790-99 at the bottom right. + +NOTE – The $TTR_{R}$ shall be generated in ATU-R from the received $TTR_{C}$ signal, and it is locked to 690 periods of upstream sampling clock (276 kHz). + +**Figure C.4/G.992.1 – ATU-R transmitter reference model for ATM transport** + +### C.3.3 ATU-C/R transmitter timing model (replacement for 5.3) + +#### C.3.3.1 TCM-ISDN crosstalk timing model (new) + +Figure C.5 shows the timing chart of the crosstalk from TCM-ISDN. + +![Timing chart of the TCM-ISDN crosstalk. The diagram shows several horizontal timing tracks: TTR (a square wave), CO (transmit ISDN then receive ISDN), RT (receive ISDN then transmit ISDN), TTR_C (offset from TTR by S_C), ATU-C TX (frames), Received TTR_C (delayed TTR_C), TTR_R (offset from Received TTR_C by S_R), and ATU-R TX (frames). It illustrates propagation delays (0 to 16 UI and 0 to 18.5 UI) and identifies periods of FEXT_R, NEXT_R, NEXT_C, and FEXT_C relative to the TTR cycles.](a2fadafce209fa3a0e9414946594192e_img.jpg) + +Timing chart of the TCM-ISDN crosstalk. The diagram shows several horizontal timing tracks: TTR (a square wave), CO (transmit ISDN then receive ISDN), RT (receive ISDN then transmit ISDN), TTR\_C (offset from TTR by S\_C), ATU-C TX (frames), Received TTR\_C (delayed TTR\_C), TTR\_R (offset from Received TTR\_C by S\_R), and ATU-R TX (frames). It illustrates propagation delays (0 to 16 UI and 0 to 18.5 UI) and identifies periods of FEXT\_R, NEXT\_R, NEXT\_C, and FEXT\_C relative to the TTR cycles. + +T1532800-99 + +1 UI = 3.125 $\mu\text{s}$ + +$\text{FEXT}_R$ and $\text{NEXT}_R$ are estimated by ATU-C + +$\text{FEXT}_C$ and $\text{NEXT}_C$ are estimated by ATU-R + +TTR TCM-ISDN timing reference + +$\text{TTR}_C$ Timing reference used in ATU-C + +Received $\text{TTR}_C$ Received $\text{TTR}_C$ at ATU-R + +$\text{TTR}_R$ Timing reference used in ATU-R + +$S_C$ $55 \times 0.9058 \mu\text{s}$ : Offset from TTR to $\text{TTR}_C$ + +$S_R$ $-42 \times 0.9058 \mu\text{s}$ : Offset from received $\text{TTR}_C$ to $\text{TTR}_R$ + +**Figure C.5/G.992.1 – Timing chart of the TCM-ISDN crosstalk** + +The data stream of TCM-ISDN is transmitted in TTR period. CO transmits the stream in the first half of the TTR period and RT transmits in the second half of the TTR period. ATU-C receives NEXT noise from the ISDN in the first half of the TTR period and FEXT noise from the ISDN in the second half of the TCM-ISDN period. On the other hand, ATU-R receives FEXT noise from the ISDN in the first half of the TTR period and NEXT noise from the ISDN in the second half of the TTR period. + +As defined in C.7.6.2 and C.7.8.3, the ATU-C shall estimate the $FEXT_R$ and $NEXT_R$ duration at ATU-R, and the ATU-R shall estimate $FEXT_C$ and $NEXT_C$ duration at ATU-C taking propagation delay on the subscribe line into consideration. + +The ATU-C shall transmit any symbols by synchronizing with the $TTR_C$ . The ATU-R shall transmit any symbols synchronizing with the $TTR_R$ generated from received $TTR_C$ . + +### C.3.3.2 Sliding window (new) + +Figure C.6 shows the timing chart of the transmission for the Annex C downstream at ATU-C. + +![Timing diagram for the sliding window for downstream symbols. The diagram shows a hyperframe of 345 symbols. The top line represents the TTR_C signal. Below it, the Crosstalk period is divided into segments labeled FEXT_R and NEXT_R. The ATU-C T Frame is shown as a sequence of symbols, with a 'Sliding Window' indicated by a dashed line. The legend identifies FEXT_R symbols as shaded and NEXT_R symbols as unshaded. The diagram is labeled T1532810-99.](b18f943d96bfcb2b1360a27b9e45e11e_img.jpg) + +The diagram illustrates the timing for downstream symbols at the ATU-C. At the top, a signal labeled $TTR_C$ is shown as a series of pulses. Below this, the 'Crosstalk period' is indicated by horizontal double-headed arrows, subdivided into $FEXT_R$ and $NEXT_R$ durations. The 'ATU-C T Frame' is represented by a horizontal row of 345 symbols. A dashed vertical line, labeled 'Sliding Window', moves across these symbols. The legend at the bottom left shows a shaded square for ' $FEXT_R$ symbol' and an unshaded square for ' $NEXT_R$ symbol'. The diagram is identified by the code 'T1532810-99' in the bottom right corner. + +Timing diagram for the sliding window for downstream symbols. The diagram shows a hyperframe of 345 symbols. The top line represents the TTR\_C signal. Below it, the Crosstalk period is divided into segments labeled FEXT\_R and NEXT\_R. The ATU-C T Frame is shown as a sequence of symbols, with a 'Sliding Window' indicated by a dashed line. The legend identifies FEXT\_R symbols as shaded and NEXT\_R symbols as unshaded. The diagram is labeled T1532810-99. + +Figure C.6/G.992.1 – Sliding window for downstream symbols + +The Sliding Window defines the transmission symbols under the crosstalk noise environment synchronized to the period of $TTR$ . The $FEXT_{C/R}$ symbol represents the symbol completely inside the $FEXT_{C/R}$ duration. The $NEXT_{C/R}$ symbol represents any symbol containing the $NEXT_{C/R}$ duration. Thus, there are more $NEXT_{C/R}$ symbols than $FEXT_{C/R}$ symbols. + +The ATU-C decides which transmission symbol is $FEXT_R$ or $NEXT_R$ symbol according to the sliding window and transmits it with the corresponding bit table. Similarly, the ATU-R decides the transmission symbol is a $FEXT_C$ or $NEXT_C$ and transmits it with the corresponding bit table. Although the phase of the sliding window is asynchronous with $TTR_{C/R}$ , the pattern is fixed to the 345 frames of the hyperframe. + +### C.3.3.3 ATU-C Symbol Synchronization to $TTR$ (new) + +345 symbols are 34 cycles with cyclic prefix of $TTR_C$ (or 32 cycles of $TTR_C$ without cyclic prefix). This implies a PLL lock at the ATU-R. + +### C.3.3.4 Dual Bitmap switching (new) + +The ATU-C transmits $FEXT_R$ symbols using Bitmap- $F_R$ (in $FEXT_R$ duration), and transmits $NEXT_R$ symbols using Bitmap- $N_R$ (in $NEXT_R$ duration) according to the result of initialization. The ATU-R transmits $FEXT_C$ symbols using Bitmap- $F_C$ (in $FEXT_C$ duration), and transmits $NEXT_C$ symbols using Bitmap- $N_C$ (in $NEXT_C$ duration) in the same manner. + +The ATU-C shall have the capability to disable Bitmap- $N_C$ and Bitmap- $N_R$ (see C.4.5 and C.5.3). + +### C.3.3.5 Loop timing at ATU-R (new) + +The phase relation between received symbol and transmitted symbol of ATU-R at the reference point U-R shall meet the phase tolerances as shown in Figure C.7. + +![Timing diagram for ATU-R loop timing. It shows two horizontal rows of five boxes representing DMT symbols. The top row is labeled 'ATU-R receive DMT symbol' and the bottom row is labeled 'ATU-R transmit DMT symbol'. A vertical dashed line passes through the boundary between the second and third boxes in both rows. A horizontal arrow points from this dashed line to another vertical dashed line that passes through the boundary between the third and fourth boxes in the bottom row. The distance between these two vertical lines is labeled '±4.5 μs + S_R'. The text '(point U-R)' is at the top left, and the identifier 'T1532820-99' is at the bottom right.](7fbdef79403f482e82031e3591c98bc2_img.jpg) + +(point U-R) + +ATU-R receive DMT symbol + +ATU-R transmit DMT symbol + +T1532820-99 + +$\pm 4.5 \mu\text{s} + S_R$ + +Timing diagram for ATU-R loop timing. It shows two horizontal rows of five boxes representing DMT symbols. The top row is labeled 'ATU-R receive DMT symbol' and the bottom row is labeled 'ATU-R transmit DMT symbol'. A vertical dashed line passes through the boundary between the second and third boxes in both rows. A horizontal arrow points from this dashed line to another vertical dashed line that passes through the boundary between the third and fourth boxes in the bottom row. The distance between these two vertical lines is labeled '±4.5 μs + S\_R'. The text '(point U-R)' is at the top left, and the identifier 'T1532820-99' is at the bottom right. + +Figure C.7/G.992.1 – Loop timing for ATU-R + +#### C.4 ATU-C functional characteristics (pertains to clause 7) + +##### C.4.1 STM transmission protocols specific functionality (pertains to 7.1) + +###### C.4.1.1 ATU-C input and output V interface for STM transport (replaces figure in 7.1.1) + +See Figure C.8. + +![Diagram of ATU-C functional interfaces for STM transport at the V-C reference point.](f21295f56ab9da5a7ea269beb8cf4afe_img.jpg) + +The diagram illustrates the functional interfaces between a Digital Network and an ATU-C at the V-C reference point. A vertical dashed line marks the V-C reference point. To the left of this line is the Digital Network, and to the right is the ATU-C. The ATU-C is connected to a twisted pair on its right side. The interfaces are represented by horizontal lines with arrows indicating the direction of data flow: + +- AS0 ( $n_0 \times 32$ kbit/s): Solid line, arrow pointing right (Digital Network to ATU-C). +- AS1 ( $n_1 \times 32$ kbit/s): Dotted line, arrow pointing right. +- AS2 ( $n_2 \times 32$ kbit/s): Dotted line, arrow pointing right. +- AS3 ( $n_3 \times 32$ kbit/s): Dotted line, arrow pointing right. +- LS0 ("C"; 16 or $m_0 \times 32$ kbit/s): Solid line, double-headed arrow. +- LS1 ( $m_1 \times 32$ kbit/s): Dotted line, double-headed arrow. +- LS2 ( $m_2 \times 32$ kbit/s): Dotted line, double-headed arrow. +- NTR: Dotted line, arrow pointing right. +- TTR: Dotted line, arrow pointing right. +- Operations, maintenance and control: Solid line, double-headed arrow. + +The label "T1532830-99" is located at the bottom right of the ATU-C block. + +Diagram of ATU-C functional interfaces for STM transport at the V-C reference point. + +NOTE 1 – Optional bearer channels (both duplex and simplex) and features are shown with dotted lines. + +NOTE 2 – TTR may be generated in the ATU-C without being provided from the V-C reference point. + +**Figure C.8/G.992.1 – ATU-C functional interfaces for STM transport at the V-C reference point** + +###### C.4.1.2 Payload transfer delay (supplements 7.1.4) + +Since Annex C uses a rate converter, the maximum payload transfer delay is longer than specified values in 7.1.4. The additional one-way transfer delay due to the rate converters shall be less than 1.7 ms for fast data and 13 ms for interleaved data. + +## C.4.2 ATM transmission protocols specific functionalities (pertains to 7.2) + +### C.4.2.1 ATU-C Input and Output V interface for ATM transport (replaces figure in 7.2.1) + +See Figure C.9. + +![Diagram of ATU-C functional interfaces to the ATM layer at the V-C reference point.](dfd09f348b50c9255f3cfe67985db9bc_img.jpg) + +The diagram illustrates the functional interfaces between the ATM layer and the ATU-C at the V-C reference point. On the left, the ATM layer is shown with two ports, PORT 0 and PORT 1. PORT 0 is connected to the ATM0 section, which contains Tx\_ATM0, Tx\_Cell\_Handshake0, Rx\_ATM0, and Rx\_Cell\_Handshake0. PORT 1 is connected to the ATM1 section, which contains Tx\_ATM1, Tx\_Cell\_Handshake1, Rx\_ATM1, and Rx\_Cell\_Handshake1. Both ATM0 and ATM1 sections are connected to the ATU-C. The ATU-C also receives NTR, TTR, and Operations, administration, maintenance and control signals from the ATM layer. The ATU-C is connected to a Twisted pair. The diagram is labeled T1532840-99. + +Diagram of ATU-C functional interfaces to the ATM layer at the V-C reference point. + +NOTE – TTR can be generated in the ATU-C without being provided from the V-C reference point. + +Figure C.9/G.992.1 – ATU-C functional interfaces to the ATM layer at the V-C reference point + +### C.4.2.2 Payload transfer delay (supplements 7.2.2) + +Since Annex C uses a rate converter, the maximum payload transfer delay is longer than specified values in 7.2.2. The additional one-way transfer delay due to the rate converters shall be less than 1.7 ms for fast data and 13 ms for interleaved data. + +## C.4.3 Framing (pertains to 7.4) + +### C.4.3.1 Superframe structure (supplements 7.4.1.1) + +Since the rate converter reorders the user data and overhead bit-level data to create hyperframes, the input data frames to the constellation encoder are different than those defined in 7.4.1.1. + +### C.4.3.2 Hyperframe structure (replaces 7.4.1.3) + +Annex C uses the hyperframe structure shown in Figure C.10. Figure C.10 shows the phase relationship between the TTRC and the hyperframe at the point U-C. Each hyperframe is composed of 5 superframes, which are numbered from 0 to 4. In order to indicate the boundary of the hyperframe, the inverse synch symbol is used for the 4th superframe (SPF#3), which is generated + +from a tone-by-tone 180-degree phase reversal of the synchronization symbol (see C.4.7.1) except for the pilot tone. + +The bit-level data stream from the rate-converter is extracted according to the size of Bitmap-FR and Bitmap-NR using the Sliding Window (see C.3.3.2). + +In order to make the bit rate to be a multiple of 32 kbit/s, the dummy bits are inserted at the end of hyperframe by the rate converter (see C.4.4.2). The hyperframe is composed of 345 DMT symbols, numbered from 0 to 344. Each symbol is assigned as FEXTR or NEXTR symbol in a FEXTR or NEXTR duration (see C.2), and the following numerical formula gives the information which duration Ndmt-th DMT symbol belongs to at ATU-C transmitter (see Figure C.11). + +For Ndmt = 0, 1, ..., 344 + +$$S = 272 \times N_{\text{dmt}} \bmod 2760$$ + +if { (S + 271 < a) or (S > a + b) } then FEXTR symbol + +else then NEXTR symbol + +where a = 1243, b = 1461 + +Thus, 128 DMT symbols are allocated in the FEXTR duration, and 217 DMT symbols are allocated in the NEXTR duration. The symbols are composed of: + +FEXTR symbol: + +Number of symbol using Bitmap-FR = 126 + +Number of synch symbol = 1 + +Number of inverse synch symbol = 1 + +NEXTR symbol: + +Number of symbol using Bitmap-NR = 214 + +Number of synch symbol = 3 + +During FEXT Bitmap mode, the ATU-C shall transmit only the pilot tone in NEXTR symbols. + +![Diagram of Hyperframe structure for downstream showing timing, superframes, and DMT symbol sequences.](88c92858439684b2103e88cb143fb98e_img.jpg) + +(point B) + +5 Superframe (= 340 frames) + +1 Superframe = 68 frames (17 ms) + +1 frame = 250 $\mu$ s + +Rate-Converter + +(point U-C, including synch symbol) + +TTR Clock(TC)#0 = 2.5 ms + +TC#27 + +TC#33 + +TTR + +ATU-R Crosstalk + +FEXT + +NEXT + +Hyperframe = 345 symbols (85 ms) + +Superframe (SPF#0) = 69 symbols (17 ms) + +SPF#1 + +SPF#2 + +SPF#3 + +SPF#4 + +ATU-C transmit DMT symbol + +F F F F N N N N N N F F S S S N F I F F N + +Sliding window + +FEXTR duration + +T1532850-99 + +1 symbol = 264 $\mu$ s (544 samples) + +Legend: + +- I** Inverse synch symbol +- S** NEXTR Synch symbol +- F** Symbol using Bitmap-FR (FEXTR duration bitmap) +- N** Symbol using Bitmap-NR (NEXTR duration bitmap) +- S** FEXTR Synch symbol + +The diagram illustrates the downstream hyperframe structure. At the top, a timeline shows 5 Superframes (340 frames) with a detail of one Superframe (68 frames, 17 ms) and one frame (250 μs). A Rate-Converter block is shown. Below, the ATU-R Crosstalk (FEXT and NEXT) is shown relative to the TTR signal. The Hyperframe (345 symbols, 85 ms) is divided into Superframes (SPF#0 to SPF#4). SPF#0 is 69 symbols (17 ms). The ATU-C transmit DMT symbol sequence is shown as a series of boxes: F F F F N N N N N N F F S S S N F I F F N. A sliding window is indicated over the first few symbols. The FEXTR duration is shown for the 'F' symbols. The TTR Clock (TC#0) is 2.5 ms. TC#27 and TC#33 are marked on the TTR signal. The legend defines the symbol types: I (Inverse synch symbol), S (NEXTR Synch symbol), F (Symbol using Bitmap-FR (FEXTR duration bitmap)), N (Symbol using Bitmap-NR (NEXTR duration bitmap)), and S (FEXTR Synch symbol). The diagram is labeled T1532850-99. + +Diagram of Hyperframe structure for downstream showing timing, superframes, and DMT symbol sequences. + +Figure C.10/G.992.1 – Hyperframe structure for downstream + +![](28a596350eb12fdc4f0a8c873cad7170_img.jpg) + +TTRC + +| | | | | | | | | | | | +|----|-----|------------|-----|-----------|-----|-----------|-----|-----------|-----|-----------| +| 0 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | +| 1 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | +| 2 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | +| 3 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | +| 4 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | +| 5 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | +| 6 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | SS | 69 | 70 | +| 7 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | +| 8 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | +| 9 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | +| 10 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | +| 11 | 112 | 113 | 114 | 115 | 116 | 117 | 118 | 119 | 120 | 121 | +| 12 | 122 | 123 | 124 | 125 | 126 | 127 | 128 | 129 | 130 | 131 | +| 13 | 132 | 133 | 134 | 135 | 136 | SS | 138 | 139 | 140 | 141 | +| 14 | 142 | 143 | 144 | 145 | 146 | 147 | 148 | 149 | 150 | 151 | +| 15 | 152 | 153 | 154 | 155 | 156 | 157 | 158 | 159 | 160 | 161 | +| 16 | 162 | 163 | 164 | 165 | 166 | 167 | 168 | 169 | 170 | 171 | +| 17 | 173 | 174 | 175 | 176 | 177 | 178 | 179 | 180 | 181 | 182 | +| 18 | 183 | 184 | 185 | 186 | 187 | 188 | 189 | 190 | 191 | 192 | +| 19 | 193 | 194 | 195 | 196 | 197 | 198 | 199 | 200 | 201 | 202 | +| 20 | 203 | 204 | 205 | SS | 207 | 208 | 209 | 210 | 211 | 212 | +| 21 | 213 | 214 | 215 | 216 | 217 | 218 | 219 | 220 | 221 | 222 | +| 22 | 223 | 224 | 225 | 226 | 227 | 228 | 229 | 230 | 231 | 232 | +| 23 | 233 | 234 | 235 | 236 | 237 | 238 | 239 | 240 | 241 | 242 | +| 24 | 244 | 245 | 246 | 247 | 248 | 249 | 250 | 251 | 252 | 253 | +| 25 | 254 | 255 | 256 | 257 | 258 | 259 | 260 | 261 | 262 | 263 | +| 26 | 264 | 265 | 266 | 267 | 268 | 269 | 270 | 271 | 272 | 273 | +| 27 | 274 | ISS | 276 | 277 | 278 | 279 | 280 | 281 | 282 | 283 | +| 28 | 284 | 285 | 286 | 287 | 288 | 289 | 290 | 291 | 292 | 293 | +| 29 | 294 | 295 | 296 | 297 | 298 | 299 | 300 | 301 | 302 | 303 | +| 30 | 304 | 305 | 306 | 307 | 308 | 309 | 310 | 311 | 312 | 313 | +| 31 | 315 | 316 | 317 | 318 | 319 | 320 | 321 | 322 | 323 | 324 | +| 32 | 325 | 326 | 327 | 328 | 329 | 330 | 331 | 332 | 333 | 334 | +| 33 | 335 | 336 | 337 | 338 | 339 | 340 | 341 | 342 | 343 | SS | + +**ISS** Inverse synch symbol    **SS** FEXTR Synch symbol    **SS** NEXTR synch symbol + FEXTR data symbol    NEXTR data symbol + +T155330-00 + +Figure C.11/G.992.1 – Symbol pattern in a hyperframe with cyclic prefix – Downstream + +### C.4.3.3 Subframe Structure (replaces 7.4.1.4) + +A subframe is 10 consecutive DMT symbols (except for synch symbols) as shown in Table C.1. The 34 subframes form a hyperframe. + +**Table C.1/G.992.1 – Subframe (downstream)** + +| Subframe No. | DMT symbol No. | Note | +|--------------|----------------|------------------------------| +| 0 | 0-9 | | +| 1 | 10-19 | | +| 2 | 20-29 | | +| 3 | 30-39 | | +| 4 | 40-49 | | +| 5 | 50-59 | | +| 6 | 60-70 | #68 is Synch Symbol | +| 7 | 71-80 | | +| 8 | 81-90 | | +| 9 | 91-100 | | +| 10 | 101-110 | | +| 11 | 111-120 | | +| 12 | 121-130 | | +| 13 | 131-141 | #137 is Synch Symbol | +| 14 | 142-151 | | +| 15 | 152-161 | | +| 16 | 162-171 | | +| 17 | 172-181 | | +| 18 | 182-191 | | +| 19 | 192-201 | | +| 20 | 202-212 | #206 is Synch Symbol | +| 21 | 213-222 | | +| 22 | 223-232 | | +| 23 | 233-242 | | +| 24 | 243-252 | | +| 25 | 253-262 | | +| 26 | 263-272 | | +| 27 | 273-283 | #275 is Inverse Synch Symbol | +| 28 | 284-293 | | +| 29 | 294-303 | | +| 30 | 304-313 | | +| 31 | 314-323 | | +| 32 | 324-333 | | +| 33 | 334-344 | #344 is Synch Symbol | + +#### C.4.4 Dual Bitmapping and Rate Conversion (replaces 7.15) + +The functions of the rate converter (see C.4.4.2), tone ordering (see C.4.6), constellation encoding, and gain scaling shall use one of two bitmaps stored in the ATU. This method is called the dual bitmap. + +##### C.4.4.1 Dual Bitmap (new) + +The Dual Bitmap method has individual bit rates under the FEXT and NEXT noise, and this needs an additional bit and gain table, $\{b_i, g_i\}$ , and ordered bit table, $b'_i$ , for the tone ordering. The dual bitmaps are switched synchronized with the sliding window pattern of NEXT/FEXT symbols. The number of bits and the relative gains to be used for every tone are calculated in the bit loading algorithm during the initialization sequence, and transmitted in R-B&G. + +##### C.4.4.2 Rate Converter (new) + +The rate converter buffering changes the data frame boundaries between the reference points B and C according to Bitmap-FR, Bitmap-NR and the Sliding Window. Two independent rate converters are prepared for fast data and interleaved data. The amount of fast and interleaved data in Bitmap-FR and Bitmap-NR shall be calculated with the following formulae and illustrated in Figure C.12: + +If $t_{Rf} \leq n_{Rmax}$ : + +$$n_{Rf} = t_{Rf}$$ + +$$n_{Ri} = n_R - n_{Rf}$$ + +$$f_{Rf} = t_{Rf}$$ + +$$f_{Ri} = f_R - f_{Rf}$$ + +If $t_{Rf} > n_{Rmax}$ : + +$$n_{Rf} = n_{Rmax}$$ + +$$n_{Ri} = 0$$ + +$$f_{Rf} = \begin{cases} f_{Rf4} = \left\lceil \frac{t_{Rf} \times 10 - n_{Rf} \times 6}{4} \right\rceil \\ f_{Rf3} = \left\lceil \frac{t_{Rf} \times 10 - n_{Rf} \times 7}{3} \right\rceil \end{cases}$$ + +$$f_{Ri} = \begin{cases} f_{Ri4} = f_R - f_{Rf4} \\ f_{Ri3} = f_R - f_{Rf3} \end{cases}$$ + +Where: + +$t_{Rf}$ is the number of allocated bits in one frame for fast bytes at the reference point B. + +$t_{Ri}$ is the number of allocated bits for interleaved bytes at the reference point B. + +$f_{Rf}$ and $n_{Rf}$ are the numbers of fast bits in Bitmap-FR and Bitmap-NR, respectively. + +$f_{Rf3}$ is the number of fast bits in Bitmap-FR if the subframe (see C.4.3.3) contains 3 Bitmap-FR except for synch symbols. + +$f_{R4}$ is the number of fast bits in Bitmap- $F_R$ if the subframe contains 4 Bitmap- $F_R$ except for synch symbols. + +$f_{Ri}$ and $n_{Ri}$ are the numbers of interleaved bits in Bitmap- $F_R$ and Bitmap- $N_R$ , respectively. + +$n_R$ is the number of total bits in Bitmap- $N_R$ , which is specified in the B&G tables. + +During FEXT Bitmap mode, $n_{Rf}$ and $n_{Ri}$ are zero. + +To convert the bit rate to be a multiple of 32 kbit/s, the dummy bits for fast data are inserted to the tail of each subframe, and the dummy bits for interleaved data are inserted to the end of the Hyperframe. The number of the dummy bits shall be as follows: + +If $t_{Rf} \leq n_{Rmax}$ : + +$$dummy_{Rf} = 0$$ + +$$dummy_{Ri} = (f_{Ri} \times 126 + n_{Ri} \times 214) - t_{Ri} \times 340$$ + +If $t_{Rf} > n_{Rmax}$ : + +$$dummy_{Rf4} = (f_{Rf} \times 4 + n_{Rf} \times 6) - t_{Rf} \times 10$$ + +$$dummy_{Rf3} = (f_{Rf} \times 3 + n_{Rf} \times 7) - t_{Rf} \times 10$$ + +$$dummy_{Ri} = (f_{Ri4} \times 96 + f_{Ri3} \times 30) - t_{Ri} \times 340$$ + +If the fast data buffer uses single latency only, the dummy bits are inserted at the tail of each FEXT symbol in the 4 Bitmap- $F_R$ constructed subframe. The number of dummy bits shall be as follows: + +$$dummy_{SRf} = f_{Rf3} - f_{Rf4}$$ + +The receiver shall determine Bitmap- $F_R$ and Bitmap- $N_R$ so that $dummy_{Ri}$ is less than 126 in the initialization sequence. At the receiver, the inserted dummy bits shall be removed. + +![Figure C.12/G.992.1 – Bit distribution for Rate Converter under Dual latency and Dual Bitmap mode. The figure shows two scenarios for bit distribution across subframes. The top part shows a general bit stream with interleaved and fast data. The middle part shows the distribution when t_Rf ≤ n_Rmax, with FEXT and NEXT symbols in subframes, and dummy bits for Ri and Rf. The bottom part shows the distribution when t_Rf > n_Rmax, with different subframe structures and dummy bits for Ri4, Ri3, and Rf3. A note indicates that the earlier bit is located at the bottom of each symbol.](0b42a43bee14d129bc811b1ad6bb2a03_img.jpg) + +NOTE – Bit Ordering: +The earlier bit is located at the bottom each symbol in this figure. + +When $t_{Rf} \leq n_{Rmax}$ + +When $t_{Rf} > n_{Rmax}$ + +T1532860-99 + +Figure C.12/G.992.1 – Bit distribution for Rate Converter under Dual latency and Dual Bitmap mode. The figure shows two scenarios for bit distribution across subframes. The top part shows a general bit stream with interleaved and fast data. The middle part shows the distribution when t\_Rf ≤ n\_Rmax, with FEXT and NEXT symbols in subframes, and dummy bits for Ri and Rf. The bottom part shows the distribution when t\_Rf > n\_Rmax, with different subframe structures and dummy bits for Ri4, Ri3, and Rf3. A note indicates that the earlier bit is located at the bottom of each symbol. + +**Figure C.12/G.992.1 – Bit distribution for Rate Converter under Dual latency and Dual Bitmap mode** + +**C.4.5 FEXT Bitmapping (replaces 7.16)** + +The FEXT Bitmapping mode uses the Dual Bitmapping technique (C.4.4) to transmit data only during FEXT. The ATU-C shall transmit only the pilot tone during the NEXTR symbol. The ATU-R disables Bitmap-NC and shall not transmit any signal during the NEXTC symbol (see Figures C.10 and C.13). + +The Dual versus FEXT bitmapping mode is selected during G.994.1 using bit "DBM" (see 10.2 and 10.3). + +#### C.4.6 Tone Ordering (replacement for 7.7) + +A DMT time-domain signal has a high peak-to-average ratio (its amplitude distribution is almost Gaussian), and large values may be clipped by the digital-to-analogue converter. The error signal caused by clipping can be considered as an additive negative impulse for the time sample that was clipped. The clipping error power is almost equally distributed across all tones in the symbol in which clipping occurs. Clipping is therefore most likely to cause errors on those tones that, in anticipation of a higher received SNR, have been assigned the largest number of bits (and therefore have the densest constellations). These occasional errors can be reliably corrected by the FEC coding if the tones with the largest number of bits have been assigned to the interleave buffer. + +The numbers of bits and the relative gains in two bitmaps to be used for every tone are calculated in ATU-R receiver, and sent back to ATU-C according to a defined protocol (see 10.9.14). The pairs of numbers are typically stored, in ascending order of frequency or tone numbers $i$ , in bit and gain tables for Bitmap- $F_R$ and Bitmap- $N_R$ . + +For Bitmap- $F_R$ , the "tone-ordered" encoding shall first assign $f_{Rf}$ bits from the rate converter (see C.4.4.2) to the tones with the smallest number of bits assigned to them, and the remaining $f_{Ri}$ bits to the remaining tones. For Bitmap- $N_R$ , it shall first assign $n_{Rf}$ bits from the rate converter to the tones with the smallest number of bits assigned to them, and the remaining $n_{Ri}$ bits to the remaining tones. + +All tones shall be encoded with the number of bits assigned to them; one tone in each bitmap may therefore have a mixture of bits from the fast and interleaved buffers. + +The ordered bit tables $b'_{iF}$ and $b'_{iN}$ shall be based on the original bit tables $b_{iF}$ and $b_{iN}$ as follows: + +For $k = 0$ to 15 { + +    From the bit table, find the set of all $i$ with the number of bits per tone $b_i = k$ + +    Assign $b_i$ to the ordered bit allocation table in ascending order of $i$ + +} + +Two ordered bit tables for Bitmap- $F_R$ and Bitmap- $N_R$ shall be prepared. A complementary de-ordering procedure should be performed in ATU-R receiver. It is not necessary, however, to send the results of the ordering process to the receiver because the bit tables $F_R$ and $N_R$ were originally generated in ATU-R, and therefore those tables have all the information necessary to perform the de-ordering. + +#### C.4.7 Modulation (pertains to 7.11) + +##### C.4.7.1 Inverse Synchronization Symbol (replaces 7.11.4) + +Except for the pilot tone, Inverse Synchronization symbol shall be generated from a tone-by-tone 180 degree phase reversal of Synchronization symbol (i.e. + maps to -, and - maps to +, for each of the 4-QAM signal constellation). + +#### C.4.8 ATU-C Downstream transmit spectral mask (replaces 7.14) + +The downstream spectral mask of Annex C shall use the same masks as Annex A. When C-MSG1 bit 16 is 0, the PSD mask specified in A.1.3 shall be used. When C-MSG1 bit 16 is 1, the PSD mask specified in A.1.2 shall be used. + +## C.5 ATU-R Functional Characteristics (pertains to clause 8) + +### C.5.1 Framing (pertains to 8.4) + +#### C.5.1.1 Superframe structure (replaces 8.4.1.1) + +The superframe structure of ATU-R transmitter is identical to that of ATU-C transmitter, as specified in C.4.3.1. + +#### C.5.1.2 Hyperframe structure (replaces 8.4.1.3) + +The hyperframe structure of ATU-R transmitter is functionally similar to that of ATU-C transmitter, except that the inverse synch symbol is used in the 1st superframe (SPF#0) (see Figure C.13). The hyperframe is composed of 345 DMT symbols, numbered from 0 to 344. Each symbol is under FEXTC or NEXTC duration (see C.5.3), and the following numerical formula gives the information which duration $N_{\text{dmt}}$ -th DMT symbol belongs to at ATU-R transmitter (see Figure C.14). + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ + +$$S = 272 \times N_{\text{dmt}} \bmod 2760$$ + +if { $(S > a)$ and $(S + 271 < a + b)$ } then FEXTC symbol + +else then NEXTC symbol + +where $a = 1315$ , $b = 1293$ + +128 DMT symbols are allocated in the FEXTC duration, and 217 DMT symbols are allocated in the NEXTC duration. The symbols are composed of: + +FEXTC symbol: + +Number of symbol using Bitmap-FC = 126 + +Number of synch symbol = 1 + +Number of inverse synch symbol = 1 + +NEXTC symbol: + +Number of symbol using Bitmap-NC = 214 + +Number of synch symbol = 3 + +During FEXT Bitmapping mode, the ATU-R shall not transmit any signal. + +![Diagram of Hyperframe structure for upstream showing timing, crosstalk, and symbol sequences.](3100b9f8708f586e472f3d9e44f10e52_img.jpg) + +(point B) + +5 Superframe (= 340 frames) + +1 Superframe = 68 frames (17 ms) + +1 frame = 250 μs + +Rate-Converter + +(point U-R, including synch symbol) + +TTR Clock(TC#0) = 2.5 ms + +TC#6 + +TC#33 + +TTRR + +ATU-R Crosstalk + +NEXT + +FEXT + +FEXT + +NEXT + +Hyperframe = 345 symbols (85 ms) + +Superframe (SPF#0) = 69 symbols (17 ms) + +SPF#1 + +SPF#2 + +SPF#3 + +SPF#4 + +ATU-C transmit DMT symbol + +N N N N N F F F F N N N + +N F F I F N S S S S + +Sliding window + +FEXTC duration + +T1532870-99 + +1 symbol = 264 μs (68 samples) + +| | | +|---|------------------------------------------------------------------------| +| I | Inverse synch symbol | +| S | NEXT C Synch symbol | +| F | Symbol using Bitmap-F C (FEXT C duration bitmap) | +| N | Symbol using Bitmap-N C (NEXT C duration bitmap) | +| S | FEXT C Synch symbol | + +The diagram illustrates the upstream hyperframe structure. At point B, a 5 Superframe (340 frames) is shown, with one Superframe being 68 frames (17 ms) and one frame being 250 μs. These frames pass through a Rate-Converter. At point U-R, including the synch symbol, the TTR Clock (TC#0) is 2.5 ms. The diagram shows the TTRR signal and ATU-R Crosstalk (NEXT and FEXT). The Hyperframe consists of 345 symbols (85 ms). It is divided into Superframes: SPF#0 (69 symbols, 17 ms), SPF#1, SPF#2, SPF#3, and SPF#4. The ATU-C transmit DMT symbol sequence is shown as N N N N N F F F F N N N for SPF#0 and N F F I F N S S S S for the subsequent superframes. A sliding window is indicated for the first superframe. The FEXTC duration is also shown. A legend defines the symbols: I (Inverse synch symbol), S (NEXTC Synch symbol), F (Symbol using Bitmap-FC (FEXTC duration bitmap)), N (Symbol using Bitmap-NC (NEXTC duration bitmap)), and S (FEXTC Synch symbol). The identifier T1532870-99 is present. + +Diagram of Hyperframe structure for upstream showing timing, crosstalk, and symbol sequences. + +**Figure C.13/G.992.1 – Hyperframe structure for upstream** + +![Symbol pattern in a hyperframe with cyclic prefix – Upstream. A grid of 34 subframes (rows 0-33) and 10 symbols per subframe. The grid shows various symbols including Inverse synch symbols (ISS), FEXT_R Synch symbols (SS), NEXT_R synch symbols (SS), FEXT_R data symbols (shaded), and NEXT_R data symbols (white).](4851479cde0f63d07f4db536c69bbdef_img.jpg) + +The diagram illustrates the symbol pattern in a hyperframe with cyclic prefix for upstream communication. It consists of 34 subframes, numbered 0 to 33 on the left. Each subframe contains 10 consecutive DMT symbols. The symbols are numbered sequentially across the subframes, starting from 0 in subframe 0 and ending at 343 in subframe 33. The symbols are categorized into different types based on their background shading and text: + +- ISS (Inverse synch symbol):** Represented by a dark gray box with the text "ISS". Symbols include 58, 136, 204, 274, and 343. +- SS (FEXTR Synch symbol):** Represented by a medium gray box with the text "SS". Symbols include 66, 117, 178, 238, and 299. +- SS (NEXTR synch symbol):** Represented by a light gray box with the text "SS". Symbols include 6, 13, 20, 27, 34, 41, 48, 55, 62, 69, 76, 83, 90, 97, 104, 111, 118, 125, 132, 139, 146, 153, 160, 167, 174, 181, 188, 195, 202, 209, 216, 223, 230, 237, 244, 251, 258, 265, 272, 279, 286, 293, 300, 307, 314, 321, 328, 335, and 342. +- FEXTR data symbol:** Represented by a dark gray box. These are the majority of the symbols in the grid. +- NEXTR data symbol:** Represented by a white box. These are the remaining symbols. + +T1535340-00 + +Symbol pattern in a hyperframe with cyclic prefix – Upstream. A grid of 34 subframes (rows 0-33) and 10 symbols per subframe. The grid shows various symbols including Inverse synch symbols (ISS), FEXT\_R Synch symbols (SS), NEXT\_R synch symbols (SS), FEXT\_R data symbols (shaded), and NEXT\_R data symbols (white). + +Figure C.14/G.992.1 – Symbol pattern in a hyperframe with cyclic prefix – Upstream + +### C.5.1.3 Subframe structure (replaces 8.4.1.4) + +A subframe is 10 consecutive DMT symbols (except for synch symbols) as shown in Table C.2. The 34 subframes form a hyperframe. + +**Table C.2/G.992.1 – Subframe (upstream)** + +| Subframe No. | DMT symbol No. | Note | +|--------------|----------------|-----------------------------| +| 0 | 0-9 | | +| 1 | 10-19 | | +| 2 | 20-29 | | +| 3 | 30-39 | | +| 4 | 40-49 | | +| 5 | 50-59 | | +| 6 | 60-70 | #68 is Inverse Synch Symbol | +| 7 | 71-80 | | +| 8 | 81-90 | | +| 9 | 91-100 | | +| 10 | 101-110 | | +| 11 | 111-120 | | +| 12 | 121-130 | | +| 13 | 131-141 | #137 is Synch Symbol | +| 14 | 142-151 | | +| 15 | 152-161 | | +| 16 | 162-171 | | +| 17 | 172-181 | | +| 18 | 182-191 | | +| 19 | 192-201 | | +| 20 | 202-212 | #206 is Synch Symbol | +| 21 | 213-222 | | +| 22 | 223-232 | | +| 23 | 233-242 | | +| 24 | 243-252 | | +| 25 | 253-262 | | +| 26 | 263-272 | | +| 27 | 273-283 | #275 is Synch Symbol | +| 28 | 284-293 | | +| 29 | 294-303 | | +| 30 | 304-313 | | +| 31 | 314-323 | | +| 32 | 324-333 | | +| 33 | 334-344 | #344 is Synch Symbol | + +**C.5.2 Dual Bitmapping and rate conversion (replaces 8.15)** + +The function of the rate converter (see C.5.2.2), tone ordering (see C.5.4), constellation encoding, and gain scaling shall use one of two bitmaps stored in the ATU. This method is called the dual bitmap. + +### C.5.2.1 Dual Bitmap (new) + +The Dual Bitmap switching shall be the same as for the downstream data, specified in C.4.4.1. The number of bits and the relative gains to be used for every tone are calculated in the bit loading algorithm during the initialization sequence, and transmitted in C-B&G. + +### C.5.2.2 Rate Converter (new) + +The rate converter buffering changes the data frame boundaries between the reference points B and C according to Bitmap-FC, Bitmap-NC and the Sliding Window. Two independent rate converters are prepared for fast data and interleaved data. The amounts of fast and interleaved data in Bitmap-FC and Bitmap-NC shall be calculated in the following formulae: + +If $t_{Cf} \leq n_{Cmax}$ : + +$$n_{Cf} = t_{Cf}$$ + +$$n_{Ci} = n_C - n_{Cf}$$ + +$$f_{Cf} = t_{Cf}$$ + +$$f_{Ci} = f_C - f_{Cf}$$ + +If $t_{Cf} > n_{Cmax}$ : + +$$n_{Cf} = n_{Cmax}$$ + +$$n_{Ci} = 0$$ + +$$f_{Cf} = \begin{cases} f_{Cf4} = \left\lceil \frac{t_{Cf} \times 10 - n_{Cf} \times 6}{4} \right\rceil \\ f_{Cf3} = \left\lceil \frac{t_{Cf} \times 10 - n_{Cf} \times 7}{3} \right\rceil \end{cases}$$ + +$$f_{Ci} = \begin{cases} f_{Ci4} = f_C - f_{C4} \\ f_{Ci3} = f_C - f_{Cf3} \end{cases}$$ + +Where: + +$t_{Cf}$ is the number of allocated bits in one frame for fast bytes at the reference point B. + +$t_{Ci}$ is the number of allocated bits for interleaved bytes at the reference point B. + +$f_{Cf}$ and $n_{Cf}$ are the numbers of fast bits in Bitmap-FC and Bitmap-NC, respectively. + +$f_{C3}$ is the number of fast bits in Bitmap-FC if the subframe (see C.5.1.3) contains 3 Bitmap-FC except for synch symbols. + +$f_{C4}$ is the number of fast bits in Bitmap-FC if the subframe contains 4 Bitmap-FC except for synch symbols. + +$f_{Ci}$ and $n_{Ci}$ are the numbers of interleaved bits in Bitmap-FC and Bitmap-NC, respectively. + +$n_C$ is the number of total bits in Bitmap-NC, which is specified in the B&G tables. + +During FEXT Bitmap mode, $n_{Cf}$ and $n_{Ci}$ are zero. + +To convert the bit rate to be a multiple of 32 kbit/s, the dummy bits for fast data are inserted to the tail of each subframe, and the dummy bits for interleaved data are inserted to the end of the Hyperframe. The number of the dummy bits shall be as follows: + +If $t_{Cf} \leq n_{Cmax}$ : + +$$dummy_{Cf} = 0$$ + +$$dummy_{Ci} = (f_{Ci} \times 126 + n_{Ci} \times 214) - t_{Ci} \times 340$$ + +If $t_{Cf} > n_{Cmax}$ : + +$$dummy_{Cf4} = (f_{Cf} \times 4 + n_{Cf} \times 6) - t_{Cf} \times 10$$ + +$$dummy_{Cf3} = (f_{Cf} \times 3 + n_{Cf} \times 7) - t_{Cf} \times 10$$ + +$$dummy_{Ci} = (f_{Ci4} \times 96 + f_{Ci3} \times 30) - t_{Ci} \times 340$$ + +If the fast data buffer uses single latency only, the dummy bits are inserted at the tail of each FEXT symbol in the 4 Bitmap-FR constructed subframe. The number of dummy bits shall be as follows: + +$$dummy_{Ci} = (f_{Ci4} \times 96 + f_{Ci3} \times 30) - t_{Ci} \times 340$$ + +The receiver shall determine Bitmap-FC and Bitmap-NC so that $dummy_{Ci}$ is less than 126 in the initialization sequence. At the receiver, the inserted dummy bits shall be removed. + +### C.5.3 FEXT Bitmapping (replaces 8.16) + +The FEXT Bitmapping mode uses the Dual Bitmapping technique (C.4.4) to transmit data only during FEXT. The ATU-C shall transmit only the pilot tone during the NEXTR symbol. The ATU-R disables Bitmap-NC and shall not transmit any signal during the NEXTC symbol (see Figures C.10 and C.13). + +The Dual versus FEXT bitmapping mode is selected during G.994.1 using bit "DBM" (see 10.2 and 10.3). + +### C.5.4 Tone Ordering (pertains to 8.7) + +The tone ordering algorithm shall be the same as for the downstream data, specified in C.4.4. + +For Bitmap-FC, the "tone-ordered" encoding shall first assign $f_{Cf}$ bits from the rate converter (see C.5.2.2) to the tones with the smallest number of bits assigned to them, and the remaining $f_{Ci}$ bits to the remaining tones. For Bitmap-NC, it shall first assign $n_{Cf}$ bits from the rate converter to the tones with the smallest number of bits assigned to them, and the remaining $n_{Ci}$ bits to the remaining tones. Two ordered bit tables for Bitmap-FC and Bitmap-NC shall be prepared. + +### C.5.5 Modulation (pertains to 8.11) + +#### C.5.5.1 Inverse synchronization symbol (replaces 8.11.4) + +Inverse Synchronization symbol shall be generated from a tone-by-tone 180 degree phase reversal of Synchronization symbol (i.e. + maps to -, and - maps to +, for each of the 4-QAM signal constellation). + +#### C.5.5.2 Gain scaling in synchronization symbol (new) + +At initialization time, the sync symbol reference transmit PSD level shall be set at the nominal PSD level $+10\log(g_{sync}^2)$ dBm/Hz, with $g_{sync}^2$ defined as the average $g_i^2$ value over the used (i.e. $b_i > 0$ ) subcarriers in the NEXT or FEXT bitmap, whichever results in the highest average gain. The sync + +symbol reference transmit PSD shall not be updated with used subcarrier gain changes during SHOWTIME. + +#### **C.5.6 ATU-R Upstream Transmit Spectral Mask (supplements 8.14)** + +The upstream spectral mask of Annex C uses the same mask as Annex A. + +### **C.6 EOC Operation and Maintenance (pertains to clause 9)** + +#### **C.6.1 ADSL line related primitives (supplements 9.3.1)** + +##### **C.6.1.1 ADSL line related near-end defects (supplements 9.3.1.3)** + +Two near-end defects are further defined: + +- *Loss-of-signal (LOS)*: The ADSL power shall be measured only in the FEXTC duration at ATU-C, or only in the FEXTR duration at ATU-R. +- *Severely errored frame (SEF)*: A SEF defect occurs when the content of two consecutively received ADSL synchronization symbols in the FEXTC duration at ATU-C, or in the FEXTR duration at ATU-R, does not correlate with the expected content over a subset of the tones. An SEF defect terminates when the content of two consecutively received ADSL synchronization symbols in the FEXTC duration at ATU-C, or in the FEXTR duration at ATU-R, correlate with the expected contents over the same subset. The correlation method, the selected subset of tones, and the threshold for declaring these defect conditions are implementation discretionary. + +##### **C.6.1.2 ADSL line related far-end defects (supplements 9.3.1.4)** + +Loss-of-signal is further defined: + +- *Loss-of-signal (LOS)*: The ADSL power shall be measured only in the FEXTC duration at ATU-C, or only in the FEXTR duration at ATU-R. + +#### **C.6.2 Test Parameters (supplements 9.5)** + +##### **C.6.2.1 Near-end test parameters (supplements 9.5.1)** + +The near-end primitives are further defined: + +- *Attenuation (ATN)*: The received signal power shall be measured only in the FEXTC duration at ATU-C, or only in the FEXTR duration at ATU-R. +- *Signal-to-Noise ratio (SNR) margin*: During FEXT Bitmap mode, this primitive represents the snr margin in the FEXTC duration at ATU-C, or in the FEXTR duration at ATU-R. + +##### **C.6.2.2 Far-end test parameters (supplements 9.5.2)** + +The far-end primitives are further defined: + +- *Attenuation (ATN)*: The received signal power shall be measured only in the FEXTC duration at ATU-C, or only in the FEXTR duration at ATU-R. +- *Signal-to-Noise ratio SNR margin*: During FEXT Bitmap mode, this primitive represents the snr margin in the FEXTC duration at ATU-C, or in the FEXTR duration at ATU-R. + +### **C.7 Initialization** + +#### **C.7.1 Initialization with Hyperframe (replaces 10.1.5)** + +The exchange of messages between ATU-C and ATU-R should be performed in FEXTC and + +FEXTR. The DMT symbol has two symbol rates: one is 4.3125 kbaud for the symbol without a cyclic prefix, and the other is $4 \times 69/68$ kbaud for the symbol with a cyclic prefix. 32 times of the TTR has the same period as 345 times of the 4.3125 kbaud, and 34 times of the TTR is the same as 345 times of $4 \times 69/68$ kHz. + +During FEXT Bitmap mode, the ATU-R shall not transmit any signal during the NEXTC symbols duration and the ATU-C shall transmit only the pilot tone as the NEXTR signal except: + +- C-PILOT1 (C-PILOT1A) which is accompanied by A48 signal (see C.7.4.1); +- C-QUIETn where no signal is transmitted. + +The ATU-C begins transmitting C-PILOT1 at the beginning of the hyperframe without cyclic prefix. The ATU-C informs the phase of the TTRC to ATU-R during C-PILOT1. The ATU-R begins transmitting R-REVERB1 at the beginning of the hyperframe without cyclic prefix. The ATU-R performs the training of any receiver equalizer using this phase information of the TTRR generated from received TTRC. + +From C-PILOT1 to C-SEGUE1, the following numerical formula gives the information which duration $N_{\text{dmt}}$ -th DMT symbol belongs to at ATU-R (see Figure C.15). + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ + +$$S = 256 \times N_{\text{dmt}} \bmod 2760$$ + +$$\text{if } \{ (S + 255 < a) \text{ or } (S > a + b) \} \quad \text{then FEXT}_R \text{ symbols}$$ + +$$\text{else} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \text{then NEXT}_R \text{ symbols}$$ + +where $a = 1243, b = 1461$ + +In order to enter C-RATES1 at the beginning of the hyperframe with cyclic prefix, the number of symbols from C-PILOT1 to C-SEGUE1 shall be a multiple of 345 DMT symbols. + +From R-REVERB1 to R-SEGUE1, the following numerical formula gives the information which duration $N_{\text{dmt}}$ -th symbol belongs to at ATU-C (see Figure C.16). + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ , + +$$S = 256 \times N_{\text{dmt}} \bmod 2760$$ + +$$\text{if } \{ (S > a) \text{ and } (S + 255 < a + b) \} \quad \text{then FEXT}_C \text{ symbols}$$ + +$$\text{else} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \text{then NEXT}_C \text{ symbols}$$ + +where $a = 1315, b = 1293$ + +From C-RATES1 to C-SEGUE3, the number of symbols is a multiple of 345 DMT symbols. The following numerical formula gives the information which duration $N_{\text{dmt}}$ -th DMT symbol belongs to. ATU-C transmits the message data in FEXTR symbols (see Figure C.11). + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ + +$$S = 272 \times N_{\text{dmt}} \bmod 2760$$ + +$$\text{if } \{ (S + 271 \geq a) \text{ and } (S \leq a + b) \} \quad \text{then NEXT}_R \text{ symbols}$$ + +$$\text{else} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \text{then FEXT}_R \text{ symbols}$$ + +where $a = 1243, b = 1461$ + +The ATU-R enters R-REVERB3 at the beginning of the hyperframe with cyclic prefix, which is extracted from received signal. From R-REVERB3 to R-SEGUE5, the number of symbols is a multiple of 345 DMT symbols. The following numerical formula gives the information which duration $N_{\text{dmt}}$ -th DMT symbol belongs to. ATU-R transmits the message data in FEXTC symbols + +(see Figure C.14). + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ + +$$S = 272 \times N_{\text{dmt}} \bmod 2760$$ + +if $\{ (S > a) \text{ and } (S + 271 < a + b) \}$ then FEXTC symbols + +else then NEXTC symbols + +where $a = 1315, b = 1293$ + +![A grid diagram showing symbol patterns for TTR_C. The grid has 32 rows (0-31) and 11 columns. Symbols are numbered sequentially. Rows 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30 are shaded (FEXT_R symbols). Rows 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31 are white (NEXT_R symbols). A legend at the bottom shows a shaded box for FEXT_R symbol and a white box for NEXT_R symbol. The code T1535350-00 is in the bottom right.](f4643d7847149c41d329ae12f8e2a519_img.jpg) + +TTRC + +0 1 2 3 4 5 6 7 8 9 10 + +1 11 12 13 14 15 16 17 18 19 20 21 + +2 22 23 24 25 26 27 28 29 30 31 + +3 32 33 34 35 36 37 38 39 40 41 42 + +4 43 44 45 46 47 48 49 50 51 52 53 + +5 54 55 56 57 58 59 60 61 62 63 64 + +6 65 66 67 68 69 70 71 72 73 74 + +7 75 76 77 78 79 80 81 82 83 84 85 + +8 86 87 88 89 90 91 92 93 94 95 96 + +9 97 98 99 100 101 102 103 104 105 106 107 + +10 108 109 110 111 112 113 114 115 116 117 118 + +11 119 120 121 122 123 124 125 126 127 128 + +12 129 130 131 132 133 134 135 136 137 138 139 + +13 140 141 142 143 144 145 146 147 148 149 150 + +14 151 152 153 154 155 156 157 158 159 160 161 + +15 162 163 164 165 166 167 168 169 170 171 172 + +16 173 174 175 176 177 178 179 180 181 182 + +17 183 184 185 186 187 188 189 190 191 192 193 + +18 194 195 196 197 198 199 200 201 202 203 204 + +19 205 206 207 208 209 210 211 212 213 214 215 + +20 216 217 218 219 220 221 222 223 224 225 + +21 226 227 228 229 230 231 232 233 234 235 236 + +22 237 238 239 240 241 242 243 244 245 246 247 + +23 248 249 250 251 252 253 254 255 256 257 258 + +24 259 260 261 262 263 264 265 266 267 268 269 + +25 270 271 272 273 274 275 276 277 278 279 + +26 280 281 282 283 284 285 286 287 288 289 290 + +27 291 292 293 294 295 296 297 298 299 300 301 + +28 302 303 304 305 306 307 308 309 310 311 312 + +29 313 314 315 316 317 318 319 320 321 322 + +30 323 324 325 326 327 328 329 330 331 332 333 + +31 334 335 336 337 338 339 340 341 342 343 344 + +■ FEXTR symbol + +□ NEXTR symbol + +T1535350-00 + +A grid diagram showing symbol patterns for TTR\_C. The grid has 32 rows (0-31) and 11 columns. Symbols are numbered sequentially. Rows 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30 are shaded (FEXT\_R symbols). Rows 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31 are white (NEXT\_R symbols). A legend at the bottom shows a shaded box for FEXT\_R symbol and a white box for NEXT\_R symbol. The code T1535350-00 is in the bottom right. + +Figure C.15/G.992.1 – Symbol pattern in a hyperframe without cyclic prefix – Downstream + +![A grid diagram showing symbol patterns for FEXT_C (shaded) and NEXT_C (white) across 32 rows (0-31) and 344 columns. The diagram includes a legend at the bottom left and a code T1535360-00 at the bottom right.](fc79c6993fa05574a318af0b7c3a360a_img.jpg) + +The figure displays a grid of symbols arranged in 32 rows (labeled 0 to 31 on the left) and 344 columns. The symbols are numbered sequentially from 0 to 344. The grid is divided into two main sections by a vertical dashed line between columns 5 and 6. The left section (columns 0-5) contains NEXTC symbols (white cells), and the right section (columns 6-344) contains FEXTC symbols (shaded cells). The symbols are arranged in a regular grid pattern, with some cells missing or empty at the ends of certain rows. A legend at the bottom left indicates that shaded cells represent FEXTC symbols and white cells represent NEXTC symbols. The code T1535360-00 is located at the bottom right of the grid. + +A grid diagram showing symbol patterns for FEXT\_C (shaded) and NEXT\_C (white) across 32 rows (0-31) and 344 columns. The diagram includes a legend at the bottom left and a code T1535360-00 at the bottom right. + +Figure C.16/G.992.1 – Symbol pattern in a hyperframe without cyclic prefix – Upstream + +## C.7.2 Handshake – ATU-C (supplements 10.2) + +### C.7.2.1 CL messages (supplements 10.2.1) + +See Table C.3. + +**Table C.3/G.992.1 – ATU-C CL message NPar(2) bit definitions for Annex C** + +| NPar(2) bit | Definition | +|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DBM | If set to ZERO, this bit shall indicate Bitmap-N R and Bitmap-N C are enabled (Dual Bitmap mode) and are used to transmit data. If set to ONE, this bit shall indicate Bitmap-N R and Bitmap-N C are disabled (FEXT Bitmap mode), i.e. only Bitmap-F R and Bitmap-F C are used to transmit data by ATU-C and ATU-R respectively. This mode selection shall be only performed by the ATU-C. If it is set to ONE in a CL message, it must be set to ONE in subsequent MS messages from either the ATU-C or ATU-R (only applicable for G.992.1 Annex C). | + +### C.7.2.2 MS messages (supplements 10.2.2) + +See Table C.4. + +**Table C.4/G.992.1 – ATU-C MS message NPar(2) bit definitions for Annex C** + +| NPar(2) bit | Definition | +|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DBM | If set to ZERO, this bit shall indicate Bitmap-N R and Bitmap-N C are enabled (Dual Bitmap mode) and are used to transmit data. If set to ONE, this bit shall indicate Bitmap-N R and Bitmap-N C are disabled (FEXT Bitmap mode), i.e. only Bitmap-F R and Bitmap-F C are used to transmit data by ATU-C and ATU-R respectively. This mode selection shall be only performed by ATU-C. This bit shall be set to ONE if it was set to ONE in a previous CL message (only applicable for G.992.1 Annex C). | + +## C.7.3 Handshake – ATU-R (supplements 10.3) + +### C.7.3.1 CLR messages (supplements 10.3.1) + +See Table C.5. + +**Table C.5/G.992.1 – ATU-R CLR message NPar(2) bit definitions for Annex C** + +| NPar(2) bit | Definition | +|-------------|-------------------------------| +| DBM | This bit shall be set to ONE. | + +### C.7.3.2 MS messages (supplements 10.3.2) + +Table C.6. + +**Table C.6/G.992.1 – ATU-R MS message NPar(2) bit definitions for Annex C** + +| NPar(2) bit | Definition | +|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DBM | If set to ZERO, this bit shall indicate Bitmap-N R and Bitmap-N C are enabled (Dual Bitmap mode) and are used to transmit data. If set to ONE, this bit shall indicate Bitmap-N R and Bitmap-N C are disabled (FEXT Bitmap mode), i.e. only Bitmap-F R and Bitmap-F C are used to transmit data by ATU-C and ATU-R respectively. This mode selection shall be only performed by ATU-C. This bit shall be set to ONE if it was set to ONE in a previous CL message (only applicable for G.992.1 Annex C). | + +### C.7.4 Transceiver Training – ATU-C (supplements 10.4) + +During transceiver training from C-REVERB1 to C-SEGUE1 except C-PILOTn and C-QUIETn, the ATU-C shall transmit both FEXTR and NEXTR symbols when Bitmap-NR is enabled (Dual Bitmap mode), and shall not transmit the NEXTR symbols except pilot tone when Bitmap-NR is disabled (FEXT Bitmap mode). The duration of each state is defined as Figure C.21. + +#### C.7.4.1 C-PILOT1 (supplements 10.4.2) + +The ATU-C shall start the NSWF (sliding window frame) counter from 0 immediately after entering C-PILOT1, and increment the NSWF counter modulo 345 after transmission of each DMT symbol. According to the sliding window function and this counter, the ATU-C decides to transmit all of the subsequent symbols in either FEXTR or NEXTR symbols (for example, see Figures C.11, C.15 and C.19). + +C-PILOT1 has two subcarriers. + +The first carrier is the pilot tone as a single frequency sinusoid $f_{C-PILOT1} = 276$ kHz ( $n_{C-PILOT1} = 64$ ) (see 10.4.2). + +The second carrier (A48) is used to transmit NEXTR/FEXTR information. The ATU-R can detect the phase information of the TTRC from the A48 signal. The constellation encoding of the 48th carrier with 2-bit constellation shall be as follows: + +(+, +): indicates a FEXTR symbol; + +(+, -): indicates a NEXTR symbol. + +#### C.7.4.2 C-PILOT1A (supplements 10.4.3) + +C-PILOT1A has two subcarriers and it is the same transmitted signal as C-PILOT1 (C.7.4.1). + +#### C.7.4.3 C-REVERB3 (supplements 10.4.11) + +In order to synchronize the first symbol of C-RATES1 with the beginning of the hyperframe and to inform the entering timing of C-RATES1 to the ATU-R, the first symbol of C-SEGUE1 shall be transmitted inside of the FEXTR duration as shown in Figure C.17. Therefore, the duration of C-REVERB3 is 3628 DMT symbols. + +![Timing diagram showing signal states and symbol durations. The top signal is TTR_C, a square wave. Below it, a timeline shows three states: C-REVERB3, C-SEGUE1, and C-RATES1. A horizontal double-headed arrow indicates a duration of '20 symbols' between the start of C-SEGUE1 and the start of C-RATES1. Below this, another timeline shows C-SEGUE1 and R-REVERB3. A horizontal double-headed arrow labeled 'the time of the detection' spans the C-SEGUE1 state. The diagram is labeled T1532880-99 in the bottom right corner.](79e37b4f8cee1318b5ed68e32a2f12a4_img.jpg) + +Timing diagram showing signal states and symbol durations. The top signal is TTR\_C, a square wave. Below it, a timeline shows three states: C-REVERB3, C-SEGUE1, and C-RATES1. A horizontal double-headed arrow indicates a duration of '20 symbols' between the start of C-SEGUE1 and the start of C-RATES1. Below this, another timeline shows C-SEGUE1 and R-REVERB3. A horizontal double-headed arrow labeled 'the time of the detection' spans the C-SEGUE1 state. The diagram is labeled T1532880-99 in the bottom right corner. + +**Figure C.17/G.992.1 – Timing diagram from C-SEGUE1 to C-RATES1** + +### C.7.5 Transceiver Training – ATU-R (supplements 10.5) + +During transceiver training from R-REVERB1 to R-SEGUE1 except R-QUIETn, the ATU-R shall transmit both FEXTC and NEXTC symbols when Bitmap-NC is enabled (Dual Bitmap mode) and shall not transmit NEXTC symbols when Bitmap-NC is disabled (FEXT Bitmap mode). The duration of each state is defined as Figure C.21. + +#### C.7.5.1 R-QUIET2 (supplements 10.5.1) + +The ATU-R enters R-REVERB1 after it completes timing recovery and Hyperframe synchronization from C-PILOT1/C-PILOT1A. + +#### C.7.5.2 R-REVERB1 (supplements 10.5.2) + +The data pattern used in R-REVERB1 is the pseudo-random upstream sequence PRU defined in 8.11.3 and repeated here for convenience: + +$$\begin{cases} d_n = 1 & \text{for } n = 1 \text{ to } 6 \\ d_n = d_{n-5} \oplus d_{n-6} & \text{for } n = 7 \text{ to } 64 \end{cases} \quad (\text{C.10-1})$$ + +The ATU-R shall start its NSWF counter immediately after entering R-REVERB1, and then increment the NSWF counter with modulo 345 from 0 when it transmits each DMT symbol. The ATU-C and ATU-R shall have the same value since hyperframe alignment between the ATU-C and ATU-R shall be maintained. According to the sliding window and this counter, the ATU-R decides to transmit all of the subsequent symbols in either the FEXTC or the NEXTC symbol. + +#### C.7.5.3 R-QUIET3 (replaces 10.5.3) + +The final symbol of R-QUIET3 accommodates the frame alignment of the transmitter to that of the receiver. It may be shortened by any number of samples. The maximum duration of R-QUIET3 is 6145 DMT symbols. + +#### C.7.5.4 R-REVERB2 (supplements 10.5.5) + +After ATU-R detects C-SEGUE1, the ATU-R enters R-SEGUE1. The maximum duration of R-REVERB2 is 3643 DMT symbols. + +### C.7.6 Channel analysis (ATU-C) (supplements 10.6) + +ATU-C shall transmit only $\text{FEXT}_R$ symbols, and shall not transmit the $\text{NEXT}_R$ symbols except the pilot tone from C-RATES1 to C-CRC2. During C-MEDLEY, the ATU-C shall transmit both $\text{FEXT}_R$ and $\text{NEXT}_R$ symbols when Bitmap- $\text{N}_R$ is enabled (Dual Bitmap mode). The ATU-C shall not transmit $\text{NEXT}_R$ symbols except the pilot tone, when Bitmap- $\text{N}_R$ is disabled (FEXT Bitmap mode). The duration of each state is defined in Figure C.21. + +#### C.7.6.1 C-SEGUE1 (supplements 10.6.1) + +The duration of C-SEGUE1 is 20 symbols in order that the first symbol of C-SEGUE1 shall be inside of the $\text{FEXT}_R$ duration. + +#### C.7.6.2 C-MEDLEY (supplements 10.6.6) + +Basically, the definition of C-MEDLEY is the same as 10.6.6, except for the duration of the SNR estimation at ATU-R for the downstream. With the periodical noise of TCM-ISDN, SNR also changes in the same cycle, as shown in Figure C.18. The ATU-C transmits the signal in both of $\text{NEXT}_R$ and $\text{FEXT}_R$ symbols, and the ATU-R estimates two SNRs from the received $\text{NEXT}_R$ and $\text{FEXT}_R$ symbols, respectively, as defined in Figure C.19. + +The following formula gives the information that received $N_{\text{dmt}}$ -th DMT symbol belongs to: + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ + +$$S = 272 \times N_{\text{dmt}} \bmod 2760$$ + +if $\{ (S + 271 < a) \text{ or } (S > d) \}$ then symbol for estimation of $\text{FEXT}_R$ SNR +if $\{ (S > b) \text{ and } (S + 271 < c) \}$ then symbol for estimation of $\text{NEXT}_R$ SNR + +where $a = 1243, b = 1403, c = 2613, d = 2704$ + +When Bitmap- $\text{N}_R$ is disabled (FEXT Bitmap mode), ATU-C shall transmit only the pilot tone as $\text{NEXT}_R$ symbol. The number of bits of $\text{NEXT}_R$ shall be no more than the number of bits of $\text{FEXT}_R$ . + +![Timing diagram for signal-to-noise ratio estimation showing TTR, crosstalk, and bitmap sequences for downstream and upstream signals.](bd0fe87fe6e236bc4778830b4f26d9e2_img.jpg) + +The diagram illustrates the timing for estimating the periodic Signal-to-Noise Ratio (SNR) in a TCM-ISDN system. It shows two signal paths over time, with various signal components and measurement intervals. + +- TTR (Transmit Time Reference):** Indicated by a vertical dashed line at the start of the first signal block. +- TCM-ISDN crosstalk at ATU-R receiver:** Shows the received signal at the ATU-R. It consists of alternating blocks of **FEXT** (shaded) and **NEXT** (white). The first block contains **FEXT**, followed by **NEXT**, then **FEXT**. The second block contains **FEXT**, followed by **NEXT**. +- TCM-ISDN crosstalk at ATU-C receiver:** Shows the received signal at the ATU-C. It consists of alternating blocks of **NEXT** (white) and **FEXT** (shaded). The first block contains **NEXT**, followed by **FEXT**, then **NEXT**. The second block contains **NEXT**, followed by **FEXT**. +- Estimation of Signal-to-Noise ratio:** A horizontal double-headed arrow labeled **C/R-MEDLEY (49152 symbols)** spans the duration of the signal blocks used for SNR estimation. +- Bitmap for Downstream:** Shows the sequence of bitmaps used for downstream signal processing. It is divided into two periods. The first period contains **Bitmap-NR** followed by **Bitmap-FR**. The second period contains **Bitmap-FR** followed by **Bitmap-NR**. +- Bitmap for Upstream:** Shows the sequence of bitmaps used for upstream signal processing. It is divided into two periods. The first period contains **Bitmap-FC** followed by **Bitmap-NC**. The second period contains **Bitmap-NC** followed by **Bitmap-FC**. + +T1532890-99 + +Timing diagram for signal-to-noise ratio estimation showing TTR, crosstalk, and bitmap sequences for downstream and upstream signals. + +**Figure C.18/G.992.1 – Estimation of periodic Signal-to-Noise Ratio** + +![A grid showing symbol patterns for S/N estimation in a hyperframe. The grid has 34 rows (0-33) and 10 columns. Symbols are numbered 0-344. The legend indicates: grey symbols for FEXT_R S/N estimation, white symbols for those not used, and hatched symbols for NEXT_R S/N estimation. The pattern repeats every 10 columns. Rows 0-33 are shown, with TTR_C at the top left and T1535370-00 at the bottom right.](779c8c5d909c8085b62fcc577f81d6ea_img.jpg) + +Legend: + +- Symbol for estimation of FEXTR S/N (Grey) +- Symbol not used for S/N estimation (White) +- Symbol for estimation of NEXTR S/N (Hatched) + +T1535370-00 + +A grid showing symbol patterns for S/N estimation in a hyperframe. The grid has 34 rows (0-33) and 10 columns. Symbols are numbered 0-344. The legend indicates: grey symbols for FEXT\_R S/N estimation, white symbols for those not used, and hatched symbols for NEXT\_R S/N estimation. The pattern repeats every 10 columns. Rows 0-33 are shown, with TTR\_C at the top left and T1535370-00 at the bottom right. + +Figure C.19/G.992.1 – Symbol pattern in a hyperframe for S/N estimation – Downstream + +C.7.7 Channel analysis (ATU-R) (supplements 10.7) + +From R-RATES1 to R-CRC2, the ATU-R shall transmit only the FEXTC symbols and shall not transmit the NEXTC symbols. In R-SEGUE2 and R-MEDLEY, the ATU-R shall transmit both FEXTC and NEXTC symbols when Bitmap-NC is enabled (Dual Bitmap mode) and shall not transmit NEXTC symbols when Bitmap-NC is disabled (FEXT Bitmap mode). The duration of each state is defined in Figure C.21. + +### **C.7.8 R-SEGUE1 (supplements 10.7.1)** + +The maximum duration of R-SEGUE1 is 14 symbols (see Figure C.17). + +#### **C.7.8.1 R-REVERB3 (supplements 10.7.2)** + +The ATU-R shall start R-REVERB3 aligned with the beginning of a Hyperframe. + +#### **C.7.8.2 R-SEGUE2 (supplements 10.7.3)** + +The duration of R-SEGUE2 is 13 symbols. + +#### **C.7.8.3 R-MEDLEY (supplements 10.7.8)** + +Basically, the definition of R-MEDLEY is the same as 10.7.8, except for the duration of the SNR estimation at ATU-C for the upstream. With the periodical noise of TCM-ISDN, SNR also changes in the same cycle, as shown in Figure C.18. ATU-R shall transmit the signal in both of $\text{NEXT}_C$ and $\text{FEXT}_C$ symbols, and ATU-C shall estimate two SNRs from the received $\text{NEXT}_C$ and $\text{FEXT}_C$ symbols, respectively, as defined in Figure C.20. + +The following numerical formula gives the information that received $N_{\text{dmt}}$ -th DMT symbol belongs to: + +For $N_{\text{dmt}} = 0, 1, \dots, 344$ + +$$S = 272 \times N_{\text{dmt}} \bmod 2760$$ + +if $\{ (S > b) \text{ and } (S + 271 < c) \}$ then symbol for estimation of $\text{FEXT}_C$ SNR + +if $\{ (S + 271 < a) \}$ then symbol for estimation of $\text{NEXT}_C$ SNR + +where $a = 1148$ , $b = 1315$ , $c = 2608$ + +When Bitmap- $N_C$ is disabled ( $\text{FEXT}$ Bitmap mode), the ATU-R shall not transmit $\text{NEXT}_C$ symbol. The number of bits of $\text{NEXT}_C$ shall be no more than the number of bits of $\text{FEXT}_C$ . + +![Figure C.20/G.992.1 – Symbol pattern in a hyperframe for S/N estimation – Upstream. The figure shows a grid of 340 symbols (0-339) arranged in 34 rows (0-33) and 10 columns. The grid is divided into three vertical sections by dashed lines: columns 0-3, 4-7, and 8-9. Rows are grouped by TTR_R values: 0-3, 4-7, 8-11, 12-15, 16-19, 20-23, 24-27, 28-31, and 32-33. A legend at the bottom indicates: solid grey for FEXT_C S/N estimation, white for not used, and hatched for NEXT_C S/N estimation. The text 'T1535380-00' is in the bottom right.](0d6ea345186864e507bfa633fb7a1acd_img.jpg) + +Legend: + +- Symbol for estimation of FEXTC S/N (solid grey) +- Symbol not used for S/N estimation (white) +- Symbol for estimation of NEXTC S/N (hatched) + +T1535380-00 + +Figure C.20/G.992.1 – Symbol pattern in a hyperframe for S/N estimation – Upstream. The figure shows a grid of 340 symbols (0-339) arranged in 34 rows (0-33) and 10 columns. The grid is divided into three vertical sections by dashed lines: columns 0-3, 4-7, and 8-9. Rows are grouped by TTR\_R values: 0-3, 4-7, 8-11, 12-15, 16-19, 20-23, 24-27, 28-31, and 32-33. A legend at the bottom indicates: solid grey for FEXT\_C S/N estimation, white for not used, and hatched for NEXT\_C S/N estimation. The text 'T1535380-00' is in the bottom right. + +**Figure C.20/G.992.1 – Symbol pattern in a hyperframe for S/N estimation – Upstream** + +### C.7.9 Exchange – ATU-C (supplements 10.8) + +During C-RATESn, C-MSGn, C-B&G, and C-CRCn, the ATU-C shall transmit the FEXTR symbol. In the other signals, the ATU-C shall transmit both FEXTR and NEXTR symbols when Bitmap-NR is enabled (Dual Bitmap mode), and shall not transmit the NEXTR symbols except pilot tone when Bitmap-NR is disabled (FEXT Bitmap mode). The duration of each state is defined in Figure C.22. + +### C.7.9.1 C-MSG2 (supplements 10.8.9) + +$$n_{1C-MSG2} = 43$$ + +$$n_{2C-MSG2} = 91$$ + +#### C.7.9.1.1 Total number of bits per symbol supported (supplements 10.8.9.3) + +The maximum number of bits per symbol is defined at the reference point B, that is calculated from the FEXTC and NEXTC downstream channel performance (e.g. if the maximum numbers of bits that can be supported in FEXTC and NEXTC symbols are 111 and 88 {Total number of bits per symbol supported} = (111 × 126 + 88 × 214)/340 = 96). + +NOTE – The number of symbols per hyperframe is 340. The number of FEXT symbols is 126. The number of NEXT symbols is 214. + +### C.7.9.2 C-B&G (replaces 10.8.13) + +C-B&G shall be used to transmit to the ATU-R the bits and gains information, Bitmap-FC { $b_1, g_1, b_2, g_2, \dots, b_{31}, g_{31}$ }, and Bitmap-NC { $b_{33}, g_{33}, b_{34}, g_{34}, \dots, b_{63}, g_{63}$ }, that are to be used on the upstream carriers. $b_i$ of Bitmap-FC indicates the number of bits to be coded by ATU-R transmitter onto the $i$ th upstream carrier in FEXTC symbols; $g_i$ of Bitmap-FC indicates the scale factor, relative to the gain that was used for that carrier during the transmission of R-MEDLEY, that shall be applied to the $i$ th upstream carrier in FEXTC symbols. Similarly, $b_i$ of Bitmap-NC indicates the number of bits onto the $(i - 32)$ th upstream carrier in NEXTC symbols; $g_i$ of Bitmap-NC indicates the scale factor that shall be applied to the $(i - 32)$ th upstream carrier in NEXTC symbols. + +Because no bits or energy will be transmitted at DC or one-half the sampling rate, $b_0, g_0, b_{32}, g_{32}, b_{64},$ and $g_{64}$ are all presumed to be zero and shall not be transmitted. + +The C-B&G information shall be mapped in a 992-bit (124 byte) message $m$ defined by: + +$$m = \{m_{991}, m_{990}, \dots, m_1, m_0\} = \{g_{63}, b_{63}, \dots, g_{33}, b_{33}, g_{31}, b_{31}, \dots, g_1, b_1\}, \quad (C.10-2)$$ + +with the MSB of $b_i$ and $g_i$ in the higher $m$ index and $m_0$ being transmitted first. The message $m$ shall be transmitted in 124 symbols, using the transmission method as described in 10.8.9. + +When Bitmap-NC is disabled (FEXT Bitmap mode), $b_i$ and $g_i$ of Bitmap-NC shall be set to zero. + +### C.7.9.3 C-SEGUE3 (replaces 10.8.16) + +The duration of C-SEGUE3 is 18 symbols. Following C-SEGUE3, the ATU-C completes the initialization and enters C-SHOWTIME. In C-SHOWTIME, ATU-C shall transmit the signal using Bitmap-FR and Bitmap-NR with the sliding window. + +When Bitmap-NR is disabled (FEXT Bitmap mode), ATU-C shall transmit only the pilot tone as NEXTR symbols. + +### C.7.10 Exchange – ATU-R (supplements 10.9) + +ATU-R shall transmit only the FEXTC symbols in R-MSGn, R-RATESn, R-B&G, R-CRCn. In other signals, the ATU-R shall transmit both FEXTC and NEXTC symbols when Bitmap-NC is enabled (Dual Bitmap mode) and shall not transmit NEXTC symbols when Bitmap-NC is disabled (FEXT Bitmap mode). The duration of each state is defined in Figure C.22. + +#### C.7.10.1 R-MSG-RA (supplements 10.9.2) + +Replace Table 10-15 with Table C.7. + +**Table C.7/G.992.1 – Assignment of 80 bits of R-MSG-RA (Annex C)** + +| Suffix(ces) of m_i
(Note) | Parameter
All reserved bits shall be set to 0 | +|------------------------------------------------------------------------------------------|----------------------------------------------------------| +| 79-68 | Reserved for ITU-T | +| 67-56 | $B_{\text{fast-max}}$ | +| 55-49 | Number of RS overhead bytes, (R) | +| 48-40 | Number of RS payload bytes, K | +| 39-32 | Number of tones carrying data (ncloaded) | +| 31-25 | Estimated average loop attenuation | +| 24-21 | Coding gain | +| 20-16 | Performance margin with selected rate option | +| 15-14 | Reserved for ITU-T | +| 13-12 | Maximum Interleave Depth | +| 11-0 | Total number of bits per DMT symbol, $B_{\text{max}}$ | +| NOTE – Within the separate fields the least significant bits have the lowest subscripts. | | + +#### **C.7.10.1.1 Total number of bits supported ( $B_{\text{max}}$ ) (replaces 10.9.2.8)** + +This parameter shall be defined as in R-MSG2, see C.7.9.1. + +#### **C.7.10.1.2 $B_{\text{fast-max}}$ (new)** + +$B_{\text{fast-max}}$ is the maximum number of bits of the fast buffer for fast data transmitted on the condition that the bits of the fast data can be equally assigned to all FEXT-symbols and NEXT-symbols. + +Fast Buffered Data $B_{\text{fast-max}}$ is $t_f$ . + +#### **C.7.10.2 R-MSG2 ( supplements 10.9.8)** + +$$N_{1\text{R-MSG2}} = 10$$ + +$$N_{2\text{R-MSG2}} = 20$$ + +##### **C.7.10.2.1 Total number of bits per symbol supported (supplements 10.9.8.3)** + +The maximum number of bits per symbol is defined at the reference point B, that is calculated from the FEXTR and NEXTR downstream channel performance. For example, if the maximum numbers of bits that can be supported in FEXTR and NEXTR symbols are 111 and 88, the total number of bits per symbol supported is $(111 \times 126 + 88 \times 214)/340 = 96$ . + +NOTE – The number of symbols per hyperframe is 340, the number of FEXT symbols is 126, and the number of NEXT symbols is 214. + +#### **C.7.10.3 R-B&G (replaces 10.9.14)** + +The purpose of R-B&G is to transmit to ATU-C the bits and gains information, Bitmap-FR $\{b_1, g_1, b_2, g_2, \dots, b_{255}, g_{255}\}$ , and Bitmap-NR $\{b_{257}, g_{257}, b_{258}, g_{258}, \dots, b_{511}, g_{511}\}$ , to be used on the downstream subcarriers. $b_i$ of Bitmap-FR indicates the number of bits to be coded by ATU-C transmitter onto the $i$ th downstream subcarrier in FEXTR symbols; $g_i$ of Bitmap-FR indicates the scale factor that shall be applied to the $i$ th downstream subcarrier in FEXTR symbols, relative to the gain that was used for that carrier during the transmission of C-MEDLEY. Similarly, $b_i$ of Bitmap-NR indicates the number of bits onto the $(i - 256)$ th downstream carrier in NEXTR symbols; $g_i$ of + +Bitmap-NR indicates the scale factor that shall be applied to the $(i - 256)$ th downstream carrier in NEXTR symbols. Because no bits or energy will be transmitted at DC or one-half the sampling rate, $b_0$ , $g_0$ , $b_{256}$ , $g_{256}$ , $b_{512}$ , and $g_{512}$ are all presumed to be zero, and are not transmitted. Because subcarrier 64 is reserved as the pilot tone, $b_{64}$ and $b_{320}$ , shall be set to 0, $g_{64}$ and $g_{320}$ shall be set to $g_{\text{sync}}$ . The value $g_{\text{sync}}$ represents the gain scaling applied to the sync symbol. + +The R-B&G information shall be mapped in a 8160-bit (1020 byte) message $m$ defined by: + +$$m = \{m_{8159}, m_{8158}, \dots, m_1, m_0\} = \{g_{511}, b_{511}, \dots, g_{257}, b_{257}, g_{255}, b_{255}, \dots, g_1, b_1\}, \quad (\text{C.10-3})$$ + +with the MSB of $b_i$ and $g_i$ in the higher $m$ index and $m_0$ being transmitted first. The message $m$ shall be transmitted in 1020 symbols, using the transmission method as described in 10.9.8. + +When Bitmap-NR is disabled (FEXT Bitmap mode), $b_i$ and $g_i$ of Bitmap-NR shall be set to zero. + +#### C.7.10.4 R-SEGUE5 (replaces 10.9.17) + +The duration of R-SEGUE5 is 13 symbols. Following R-SEGUE-5, ATU-R completes the initialization and enters R-SHOWTIME. In R-SHOWTIME, ATU-R shall transmit the signal using Bitmap-FC and Bitmap-NC with the sliding window. + +When Bitmap-NC is disabled (FEXT Bitmap mode), ATU-R shall not transmit NEXTC symbols. + +![Timing diagram of the initialization sequence – Part 1. The diagram shows two columns for ATU-C and ATU-R. ATU-C starts with C-GALF2 and C-FLAG2, followed by C-QUIET2. ATU-R starts with R-GALF2 and R-FLAG2, followed by R-QUIET2. The diagram includes various fields like C-REVERB1, C-PILOT2, C-ECT, C-REVERB2, C-PILOT3, C-QUIET5, C-REVERB3, C-SEGUE1, C-RATES1/C-CRC1, C-MSG1/C-CRC2, and C-MEDLEY. ATU-R fields include R-REVERB1, R-QUIET3, R-ECT, R-REVERB2, R-SEGUE1, R-REVERB3, R-SEGUE2, R-RATES1/R-CRC1, R-MSG1/R-CRC2, and R-MEDLEY. Timing parameters include sample counts like 345n, 1536, 9216, 4608, 3628, 20, 2884, 49152, and 12477. Notes 1-5 are referenced throughout the diagram.](c71cc20c24544f057770d4066ecaadc4_img.jpg) + +The diagram illustrates the timing sequence for initialization between ATU-C and ATU-R. It is divided into two main columns: ATU-C (left) and ATU-R (right). + +- ATU-C Sequence:** + - Initial symbols: C-GALF2 (G.994.1) and C-FLAG2 (G.994.1). + - C-QUIET2: Duration $\geq 128$ to $\leq 2048$ samples. + - Conditional symbols (Note 5): + - If R-ACK2 then C-PILOT1 + - If R-ACK1 then C-PILOT1A + - Duration $345n$ ( $n \leq 38$ ) samples. + - C-QUIET3A: Duration $\leq 32$ samples. + - C-REVERB1: Duration 1536 samples. (Note 2) + - C-PILOT2: Duration 9216 samples. (Note 5) + - C-ECT: Duration 1536 samples. + - C-REVERB2: Duration 4608 samples. (Note 2) + - Conditional symbols (Note 5): + - If R-ACK2 then C-PILOT3 + - If R-ACK1 then C-QUIET5 + - Duration 1536 samples. + - C-REVERB3: Duration 3628 samples. (Note 2) + - C-SEGUE1: Duration 20 samples. + - C-RATES1/C-CRC1 and C-MSG1/C-CRC2: Duration 2884 samples. (Note 1) + - C-MEDLEY: Duration 49152 samples. (Note 2) +- ATU-R Sequence:** + - Initial symbols: R-GALF2 (G.994.1) and R-FLAG2 (G.994.1). + - R-QUIET2: Duration $\leq 15500$ samples. + - Blank interval (Note 5): Duration $345n$ ( $1 \leq n \leq 33$ ) samples. + - R-REVERB1: Duration 12477 samples. (Note 4) + - R-QUIET3: Duration $\geq 6144$ to $\leq 6145$ samples. + - R-ECT: Duration 1536 samples. + - R-REVERB2: Duration $\geq 3634$ to $\leq 3643$ samples. + - R-SEGUE1: Duration $5 \leq, \leq 14$ samples. + - R-REVERB3: Duration $345n - 13$ ( $9 \leq n \leq 16$ ) samples. + - R-SEGUE2: Duration 13 samples. + - R-RATES1/R-CRC1 and R-MSG1/R-CRC2: Duration 1254 samples. (Note 3) + - R-MEDLEY: Duration 49152 samples. (Note 4) +- Timing Relationships:** + - The "Beginning of Hyperframe" is marked at the start of C-QUIET2 and R-QUIET2. + - A "Last symbol may be shortened by n samples" is indicated for the transition between C-REVERB2 and C-PILOT3/QUIET5. + - An "Introduction of guard time" is indicated between C-SEGUE1 and C-RATES1/C-CRC1. + - Vertical double-headed arrows indicate durations for various intervals, such as 1725 samples between the start of C-REVERB1 and the start of the conditional symbols. + - Horizontal double-headed arrows indicate durations for intervals like $345n + 208$ ( $0 \leq n \leq 7$ ) samples between the start of C-MEDLEY and the start of R-SEGUE2. + +Timing diagram of the initialization sequence – Part 1. The diagram shows two columns for ATU-C and ATU-R. ATU-C starts with C-GALF2 and C-FLAG2, followed by C-QUIET2. ATU-R starts with R-GALF2 and R-FLAG2, followed by R-QUIET2. The diagram includes various fields like C-REVERB1, C-PILOT2, C-ECT, C-REVERB2, C-PILOT3, C-QUIET5, C-REVERB3, C-SEGUE1, C-RATES1/C-CRC1, C-MSG1/C-CRC2, and C-MEDLEY. ATU-R fields include R-REVERB1, R-QUIET3, R-ECT, R-REVERB2, R-SEGUE1, R-REVERB3, R-SEGUE2, R-RATES1/R-CRC1, R-MSG1/R-CRC2, and R-MEDLEY. Timing parameters include sample counts like 345n, 1536, 9216, 4608, 3628, 20, 2884, 49152, and 12477. Notes 1-5 are referenced throughout the diagram. + +**Figure C.21/G.992.1 – Timing diagram of the initialization sequence – Part 1** + +![Timing diagram of the initialization sequence – Part 2. The diagram shows two vertical timelines for ATU-C and ATU-R. ATU-C starts with C-REVERB4 (345n - 304 symbols, 7 ≤ n ≤ 20), followed by C-SEGUE2 (18 symbols), C-RATES-RA/C-CRC-RA1 C-MSG-RA/C-CRC-RA2 (347 symbols), C-REVERB-RA (345n - 20 symbols, 2 ≤ n ≤ 16), C-SEGUE-RA (18 symbols), C-MSG2/C-CRC-3 C-RATES2/C-CRC4 (22 symbols), C-B&G/C-CRC5 (336 symbols), C-REVERB5 (345n - 31 symbols, 10 ≤ n ≤ 20), C-SEGUE3 (18 symbols), and SHOWTIME. ATU-R starts with R-MEDLEY, R-REVERB4 (296 symbols), R-SEGUE3 (13 symbols), R-MSG-RA/R-CRC-RA1 R-RATES-RA/R-CRC-RA2 (40 symbols), R-REVERB-RA (345n - 53 symbols, 3 ≤ n ≤ 16), R-SEGUE-RA (13 symbols), R-MSG2/R-CRC-3 R-RATES2/R-CRC4 (27 symbols), R-REVERB5 (345n - 40 symbols, 3 ≤ n ≤ 16), R-SEGUE4 (13 symbols), R-B&G/R-CRC5 (2757 symbols), R-REVERB6 (345n - 10 symbols, 2 ≤ n ≤ 16), R-SEGUE5 (13 symbols), and SHOWTIME. Horizontal arrows indicate timing offsets between ATU-C and ATU-R segments, such as 345n + 287 (0 ≤ n ≤ 6) between C-REVERB4 and R-REVERB-RA. Vertical double-headed arrows indicate durations of specific segments. Notes 1-4 are referenced at various points. The maximum initialization time is 26.9 seconds. The diagram is labeled T1532910-99.](61887c08b198861558621bc776880d6d_img.jpg) + +Timing diagram of the initialization sequence – Part 2. The diagram shows two vertical timelines for ATU-C and ATU-R. ATU-C starts with C-REVERB4 (345n - 304 symbols, 7 ≤ n ≤ 20), followed by C-SEGUE2 (18 symbols), C-RATES-RA/C-CRC-RA1 C-MSG-RA/C-CRC-RA2 (347 symbols), C-REVERB-RA (345n - 20 symbols, 2 ≤ n ≤ 16), C-SEGUE-RA (18 symbols), C-MSG2/C-CRC-3 C-RATES2/C-CRC4 (22 symbols), C-B&G/C-CRC5 (336 symbols), C-REVERB5 (345n - 31 symbols, 10 ≤ n ≤ 20), C-SEGUE3 (18 symbols), and SHOWTIME. ATU-R starts with R-MEDLEY, R-REVERB4 (296 symbols), R-SEGUE3 (13 symbols), R-MSG-RA/R-CRC-RA1 R-RATES-RA/R-CRC-RA2 (40 symbols), R-REVERB-RA (345n - 53 symbols, 3 ≤ n ≤ 16), R-SEGUE-RA (13 symbols), R-MSG2/R-CRC-3 R-RATES2/R-CRC4 (27 symbols), R-REVERB5 (345n - 40 symbols, 3 ≤ n ≤ 16), R-SEGUE4 (13 symbols), R-B&G/R-CRC5 (2757 symbols), R-REVERB6 (345n - 10 symbols, 2 ≤ n ≤ 16), R-SEGUE5 (13 symbols), and SHOWTIME. Horizontal arrows indicate timing offsets between ATU-C and ATU-R segments, such as 345n + 287 (0 ≤ n ≤ 6) between C-REVERB4 and R-REVERB-RA. Vertical double-headed arrows indicate durations of specific segments. Notes 1-4 are referenced at various points. The maximum initialization time is 26.9 seconds. The diagram is labeled T1532910-99. + +NOTE 1 – The ATU-C shall transmit the $FEXT_R$ symbols, and shall not transmit as $NEXT_R$ symbols except the pilot tone. + +NOTE 2 – The ATU-C shall transmit both $FEXT_R$ and $NEXT_R$ symbols, when $Bitmap-N_R$ is enabled (Dual Bitmap mode). + +ATU-C shall not transmit the $NEXT_R$ symbols except pilot tone, when $Bitmap-N_R$ is disabled ( $FEXT$ Bitmap mode). + +NOTE 3 – The ATU-R shall transmit the $FEXT_C$ symbols, and shall not transmit the $NEXT_C$ symbols. + +NOTE 4 – The ATU-R shall transmit both $FEXT_C$ symbols, when $Bitmap-N_C$ is enabled (Dual Bitmap mode). ATU-R shall not transmit $NEXT_C$ symbols, when $Bitmap-N_C$ is disabled ( $FEXT$ Bitmap mode). + +NOTE 5 – The ATU-C shall transmit both $FEXT_R$ and $NEXT_R$ symbols. + +**Figure C.22/G.992.1 – Timing diagram of the initialization sequence – Part 2** + +## C.8 AOC On-line adaptation and reconfiguration (pertains to clause 11) + +### C.8.1.1 Bit swap request (replaces 11.2.3) + +The receiver shall initiate a bit swap by sending a bit swap request to the transmitter via the AOC channel. This request tells the transmitter which subcarriers are to be modified. The format of the request is shown in Table C.8. + +**Table C.8/G.992.1 – Format of the bit swap request message** + +| Message header | Message field 1-4 | | | +|--------------------------------------|-------------------------|---------------------|------------------------------| +| {11111111 2 }
(8 bits) | Bitmap index
(1 bit) | Command
(7 bits) | Subchannel index
(8 bits) | + +The request shall comprise nine bytes as follows: + +- an AOC message header consisting of 8 binary ones; +- message fields 1-4, each of which consists of one-bit bitmap index, a seven-bit command followed by a related eight-bit subchannel index. One-bit bitmap index and valid seven-bit commands for the bit swap message shall be as shown in Table C.9. In Table C.9, the MSB for the bit swap request command represents the Bitmap index. For downstream data, Bitmap index equals 0 indicates Bitmap-FR, and Bitmap index equals 1 indicates Bitmap-NR. Similarly for upstream data, Bitmap index equals 0 indicates Bitmap-FC, and 1 indicates Bitmap-NC. The eight-bit subchannel index is counted from low to high frequencies with the lowest frequency subcarrier having the number zero. The subcarrier index zero shall not be used; +- the bit swap between FEXTC/R symbols and NEXTC/R symbols is not allowed. + +**Table C.9/G.992.1 – Bit swap request command** + +| Value
(8 bit) | Interpretation | +|-----------------------------------------------------------------------------------------------------------------|----------------------------------------------| +| y0000000 2 | Do nothing | +| y0000001 2 | Increase the number of allocated bits by one | +| y0000010 2 | Decrease the number of allocated bits by one | +| y0000011 2 | Increase the transmitted power by 1 dB | +| y0000100 2 | Increase the transmitted power by 2 dB | +| y0000101 2 | Increase the transmitted power by 3 dB | +| y0000110 2 | Reduce the transmitted power by 1 dB | +| y0000111 2 | Reduce the transmitted power by 2 dB | +| y0001xxx 2 | Reserved for vendor discretionary commands | +| NOTE – y is "0" for FEXT C/R symbols, and "1" for NEXT C/R symbols of the Sliding Window. | | + +The bit swap request message (i.e. header and message fields) shall be transmitted five consecutive times. + +To avoid $g_i$ divergence between ATU-C and ATU-R after several bit swaps, for a $g_i$ update of $\Delta$ dB the new $g_i$ value should be given by: + +$$g_i' = (1/512) \times \text{round}(512 \times g_i \times 10^{\Delta/20}) \quad (\text{C.11-1})$$ + +### C.8.1.2 Extended bit swap request (supplements 11.2.4) + +The format of the extended bit swap request is shown in Table C.10. + +**Table C.10/G.992.1 – Format of the bit swap request message** + +| Message header | Message field 1-6 | | | +|--------------------------------------|-------------------------|---------------------|------------------------------| +| {11111100 2 }
(8 bits) | Bitmap index
(1 bit) | Command
(7 bits) | Subchannel index
(8 bits) | + +In the same manner as the bit swap request, each of the message fields of the extended bit swap request consists of one-bit bitmap index, a seven-bit command followed by a related eight-bit subchannel index. + +### C.8.1.3 Bit swap acknowledge (supplements 11.2.5) + +The bit swap superframe counter number shall only indicate the last superframe (SPF#4) of a hyperframe. + +The new bit and/or transmit power table(s) shall then take effect starting from the first frame (frame 0) of SPF#0 of a hyperframe. + +If the bit swap superframe counter number contained in the received bit swap acknowledge message does not indicate SPF#4, then the new table(s) shall take effect starting from frame 0 of SPF#0 of the next hyperframe. + +## ANNEX D + +### ATU-C and ATU-R state diagrams + +#### D.1 Introduction + +This annex provides state diagrams for the ATU-C and ATU-R, some portions of which are mandatory to guarantee interworking between different manufacturers' units, and some portions of which are presented here as an example only. Their functions may be required or desired, but the implementation is left to the vendor. + +#### D.2 Definitions + +The following terms and abbreviations are used in this annex. Where states or events have been defined elsewhere in this Recommendation, the definitions are referenced here for convenience. + +**D.2.1 LOF-rs:** Loss of ADSL frame synch/resync event. This event occurs when some algorithm, which may be vendor-specific, determines that a resync attempt is required. Note that this LOF-rs event is probably (but not required to be) related to the SEF (severely errored frame) defect defined for operations and maintenance (see 9.3). + +**D.2.2 persistent LOF:** Persistent LOF is declared after $2.5 \pm 0.5$ s of near-end LOF failure with SEF defect still present. LOF failure and SEF defect are defined for operations and maintenance in 9.3. + +**D.2.3 persistent LOS:** Persistent LOS is declared after $2.5 \pm 0.5$ s of near-end LOS failure with LOS defect still present. LOS failure and LOS defect are defined for operations and maintenance in 9.3. + +**D.2.4 high BER:** High bit error rate in received data: detected by thresholding #CRC errors (near-end CRC-8i and CRC-8ni error anomalies, defined in 9.3) over some period of time. + +**D.2.5 host control channel:** An ATU-C configuration control channel from some host controller, such as an ACOT (ADSL Central Office Terminal), which controls one or more ATU-C line units. Note that this channel has no relationship or direct interworking with the 64 or 16 kbit/s "C" bearer channel, which is sometimes also called a control channel. + +**D.2.6 reconfig1:** A channelization reconfiguration that can be accomplished without resetting certain key portions of the data framing, transmitter, or receiver functions (6 and 7), and thus can be performed without disrupting channels that would not change as a result of the reconfiguration. For example, if four 1.536 Mbit/s simplex channels are currently active and are all allocated to the interleave data buffer, then a reconfiguration that requires two of them to remain active, and the other two to be replaced by a 3.088 Mbit/s channel would qualify as a reconfig1. + +**D.2.7 reconfig2:** A channelization reconfiguration that requires resetting of some key portion of the data framing, transmitter, or receiver functions (6 and 7), and which thus cannot be achieved without loss of some user data. This reconfiguration request will require a fast retrain. Examples are: + +- a change from the default bearer channel rates to optional rates, such as a request for a reconfiguration from a single 6.144 Mbit/s simplex bearer to a 6.312 Mbit/s simplex bearer, which requires a change in aggregate transmitted bit rate, FEC codeword size, and resetting the interleave/deinterleave functions; +- if four 1.536 Mbit/s simplex channels are currently active and are all allocated to the interleave data buffer, then a reconfiguration that requires one or more of them to move to the fast data buffer would require a fast retrain to allocate the extra AEX byte for the fast data buffer, to change the FEC codeword parameters of the interleaved data buffer, and to reset the interleave/deinterleave functions. + +### D.3 State Diagrams + +State diagrams are given in Figure D.1 for the ATU-C, and in Figure D.2 for the ATU-R. States are indicated by ovals, with the name of the state given within the oval. The states are defined in Table D.1 for the ATU-C and in Table D.2 for the ATU-R. Transitions between states are indicated by arrows, with the event causing the transition listed next to the arrow. For some events, the source of the event is indicated with letter(s) and a colon preceding the event name; a key to the source events is provided at the bottom of each figure. All states except *Retrain* and *Resync* are mandatory. + +In the state diagram for the ATU-C, a C-IDLE state would be desired to guarantee a quiet mode, which may be useful prior to provisioning, to allow certain tests (e.g. MLT), or to discontinue service. A selftest function is desirable, but it may be a vendor/customer option to define when selftest occurs (e.g. always at power-up or only under CO control), and which transition to take after successfully completing selftest [e.g. enter C-IDLE, or enter C-SILENT1 (see Recommendation G.994.1), or enter C-Activate/Init/Train]. + +A variety of "host controller" commands (events preceded by "c:") are shown as non-mandatory in the ATU-C state diagram to provide example events and transitions between states. The way in which these events are implemented is left to the vendor, since many options are possible (e.g. separate host controller port on the ATU-C, switches or other front-panel controls, fixed options). + +A *Retrain* state is shown as non-mandatory in both state diagrams (fast retrain is still under study). A *Resync* state is shown as non-mandatory in both state diagrams, to be left as a vendor option that may use vendor proprietary algorithms. + +![Figure D.1/G.992.1 – State diagram for the ATU-C](021490adcafe4e26498ead48f8eb09fe_img.jpg) + +``` + + stateDiagram-v2 + [*] --> C_SELFTEST: Power on + C_SELFTEST --> C_UNIT_FAIL: fail + C_UNIT_FAIL --> C_SELFTEST: c:selftest + C_SELFTEST --> C_SILENT1: pass + C_SILENT1 --> C_SELFTEST: c:selftest + C_UNIT_FAIL --> C_IDLE: c:activate + C_SILENT1 --> C_IDLE: c:idle_ignore + C_IDLE --> C_SILENT1: c:idle_monitor + C_SILENT1 --> C_INIT_TRAIN: r:R-TONES-REQ + C_INIT_TRAIN --> C_SILENT1: retry timeout + C_INIT_TRAIN --> C_IDLE: c:idle_ignore + C_IDLE --> C_INIT_TRAIN: c:activate + C_INIT_TRAIN --> C_SHOWTIME: success + C_SHOWTIME --> C_SILENT1: Persistent LOS or LOF + C_SHOWTIME --> C_RESYNC: lof-rs + C_RESYNC --> C_SILENT1: Persistent LOS or LOF + C_RESYNC --> C_SHOWTIME: success + C_SHOWTIME --> C_RETRAIN: high_BER or c:reconfig2 + C_RETRAIN --> C_SILENT1: Persistent LOS or LOF + C_RETRAIN --> C_SHOWTIME: success + C_SHOWTIME --> C_IDLE: c:idle_ignore + + state C_SILENT1: C-SILENT1 (G.994.1) + state C_IDLE: C-IDLE (ignore ATU-R) + state C_INIT_TRAIN: G.994.1/C-INIT/TRAIN + state C_RESYNC: C-RESYNC + state C_RETRAIN: C-RETRAIN + state C_SHOWTIME: C-SHOWTIME + +``` + +Detailed description of Figure D.1: The diagram shows the operational states of an ATU-C. It starts with 'Power on' leading to 'C-SELFTEST'. A 'fail' leads to 'C-UNIT-FAIL', while a 'pass' (bold transition) leads to 'C-SILENT1 (G.994.1)'. From 'C-SILENT1', receiving 'r:R-TONES-REQ' (bold) leads to 'G.994.1/C-INIT/TRAIN'. A 'success' (bold) from there leads to the main operational state 'C-SHOWTIME'. Optional states 'C-RESYNC' and 'C-RETRAIN' (in italics) can be entered from 'C-SHOWTIME' under specific conditions like 'lof-rs' or 'high\_BER'. Various 'c:' commands from a host controller can force transitions to 'C-IDLE' or back to 'C-SELFTEST'. Persistent Loss of Signal (LOS) or Loss of Frame (LOF) generally returns the system to the 'C-SILENT1' state. + +T1532920-99 + +Figure D.1/G.992.1 – State diagram for the ATU-C + +NOTE 1 – Event Sources: + c: host controller command. + r: received from ATU-R. + NOTE 2 – The main sequence of states is shown in **bold**. + NOTE 3 – Optional (vendor discretionary) states are shown in *italics*. + NOTE 4 – States are defined in Table D.1; terms in D.2. + +**Figure D.1/G.992.1 – State diagram for the ATU-C** + +194      **Recommendation G.992.1 (06/99)** + +![](39729be7ec83c3de8e480061966e4505_img.jpg) + +``` + + graph TD + PowerOn((Power on)) --> R_SELFTEST + R_SELFTEST[R-SELFTEST] -- fail --> R_UNIT_FAIL[R-UNIT-FAIL] + R_SELFTEST -- pass --> R_SILENT0[R-SILENT0 +(G.994.1)] + R_SELFTEST -- "pass_ +idle_ignore" --> R_IDLE[R-IDLE +(ignore ATU-C)] + R_UNIT_FAIL -- r:idle_ignore --> R_IDLE + R_IDLE -- r:selftest --> R_SELFTEST + R_IDLE -- r:activate --> R_SILENT0 + R_SILENT0 -- r:idle_ignore --> R_IDLE + R_SILENT0 -- c:silent bit --> G_994_1[G.994.1] + G_994_1 -- fail or timeout --> R_SILENT0 + G_994_1 --> R_INIT_TRAIN[R-INIT/TRAIN] + R_INIT_TRAIN --> R_SHOWTIME[R-SHOWTIME] + R_SHOWTIME -- "Persistent +LOS or LOF" --> R_SILENT0 + R_SHOWTIME -- lof-rs --> R_RESYNC[R-RESYNC] + R_RESYNC -- success --> R_SHOWTIME + R_RESYNC -- "Persistent +LOS or LOF" --> R_SILENT0 + R_SHOWTIME -- "high_BER +or r:reconfig2" --> R_RETRAIN[R-RETRAIN] + R_RETRAIN -- success --> R_SHOWTIME + R_RETRAIN -- "timeout or +r:activate" --> R_SILENT0 + R_SHOWTIME -- r:idle_ignore --> R_IDLE + R_SHOWTIME -- EOC:selftest --> R_SELFTEST + + style R_SELFTEST stroke-width:2px + style R_SILENT0 stroke-width:2px + style G_994_1 stroke-width:2px + style R_INIT_TRAIN stroke-width:2px + style R_SHOWTIME stroke-width:2px + +``` + +T1532930-99 + +NOTE 1 – Event Sources: + r: host controller command. + c: received from ATU-C. + +NOTE 2 – The main sequence of states is shown in **bold**. + +NOTE 3 – Optional (vendor discretionary) states are shown in *italics*. + +NOTE 4 – States are defined in Table D.2; terms in D.2. + +**Figure D.2/G.992.1 – State diagram for the ATU-R** + +**Recommendation G.992.1 (06/99)**     195 + +**Table D.1/G.992.1 – ATU-C state definitions** + +| State Name | Description | +|-------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| C-SELFTEST | Unit performs self test. Transmitter and receiver off (quiet at U-C interface); no response to host control channel (e.g. ACOT) | +| C-UNIT-FAIL | (self test failed)
Monitor host control channel if possible (could allow ATU-x host controller to retrieve self test results) | +| C-IDLE
(Idle; ignore ATU-R) | Transmitter and receiver off (no response to R-TONES-REQ).
Monitor host control channel | +| C-TONES | Transmit C-TONES and transition back to C-IDLE | +| C-SILENT1
(see G.994.1)
(Idle; monitor ATU-R) | Transmitter off
Receiver on, monitor for R-TONES-REQ;
if detected, transition to C-Activate/Init/Train state
Monitor host control channel | +| G.994.1/
C-INIT/TRAIN
(Starts with State
C-TONES of G.994.1;
includes 10.2, 10.4, 10.6
and 10.8) | Initialize Train_Try_Counter
while (--Train_Try_Counter $\geq$ 0)
{
Transmit C-TONES
Start timer
If G.994.1 begins before timer expires
proceed with initialization/training
If successful, transition to C-ACTIVE
}
Transition to C-SILENT1
Monitor host control channel | +| C-SHOWTIME
(Steady State Data
Transmission;
6, 9.3 and 11) | Perform steady state bit pump functions (user data channels active)
Allow bit swaps and non-intrusive reconfigurations (reconfig1)
Monitor host control channel
Monitor alarms, EOC, AOC
If LOS or LOF event, transition to C-Activate/Init/Train | +| C-RESYNC
(non-mandatory; vendor
proprietary) | (State is entered when some algorithm, possibly based on loss of
ADSL synch framing, determines that resync is required)
Declare SEF (defined in 9.3.1.3) – user data transmission has been
disrupted
If signal present (i.e. not LOS)
Attempt to find synch pattern and realign (vendor proprietary)
If successful, remove SEF and transition to C-ACTIVE
else time-out on SEF, declare LOF event, transition to
C-Activate/Init/Train
else time-out on LOS, declare LOS event, transition to
C-Activate/Init/Train | +| C-RETRAIN
(fast retrain for further
study) | (State can only be entered if received signal is still present and if
ADSL frame synch is still maintained)
Declare SEF (defined in 9.3.1.3) – user data transmission has been
disrupted
If signal present (i.e. not LOS)
Channel ID and bit allocation calculation
Reset Data Framing and V-interface circuits
If successful, remove SEF and return to C-ACTIVE
else time-out on SEF, declare LOF event, transition to
C-Activate/Init/Train
else time-out on LOS, declare LOS event, transition to
C-Activate/Init/Train | + +**Table D.2/G.992.1 – ATU-R state definitions** + +| State Name | Description | +|----------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| R-SELFTEST | Unit performs self test. Transmitter and receiver off (quiet at U-R interface).
If self test passes and receiver is in automatic training mode, transition to R-SILENT0
If self test passes and receiver is under external control, transition to R-IDLE
else transition to R-UNIT-FAIL | +| R-UNIT-FAIL | (self test failed -- no exit from this state, except to cycle power) | +| R-SILENT0/
G.994.1 | See G.994.1
Monitor host control channel | +| R-INIT/TRAIN
(Starts with State
R-TONES-REQ of
G.994.1; includes 10.3,
10.5, 10.7 and 10.9) | Transmit R-ACK
Proceed with Initialization and Training Sequence
If successful, transition to R-ACTIVE
else transition to R-SILENT0 | +| R-SHOWTIME
(Steady State Data
Transmission; 7, 9.3,
and 11) | Perform steady state bit pump functions (user data channels active)
Allow bit swaps and non-intrusive reconfigurations (reconfig1)
Monitor alarms, EOC, AOC, host control channel
If LOS or LOF event, transition to R-SILENT0 | +| R-IDLE
(ignore ATU-C) | Transmitter and receiver off, monitor host control channel | +| R-RESYNC
(non-mandatory;
vendor proprietary) | (State is entered when some algorithm, probably based on loss of ADSL synch framing, determines that resync is required)
Declare SEF (defined in 9.3.1.3) – user data transmission has been disrupted
If signal present (i.e. not LOS)
Attempt to find synch pattern and realign (vendor proprietary)
If successful, remove SEF and transition to R-ACTIVE
else time-out on SEF, declare LOF event, transition to R-SILENT0
else time-out on LOS, declare LOS event, transition to R-SILENT0 | +| R-RETRAIN
(fast retrain for further
study) | (State can only be entered if received signal is still present and if ADSL frame synch is still maintained)
Declare SEF (defined in 9.3.1.3) – user data transmission has been disrupted
Reset Data Framing and T-interface circuits
If signal present (i.e. not LOS)
Channel ID and bit allocation calculation
If successful, remove SEF and transition to R-ACTIVE
else time-out on SEF, declare LOF event, transition to R-SILENT0
else time-out on LOS, declare LOS event, transition to R-SILENT0 | + +## ANNEX E + +### POTS and ISDN-BA splitters + +The purpose of the POTS splitter is twofold. For ADSL signals, protection from the high-frequency transients and impedance effects that occur during POTS operation – ringing transients, ring trip transients, and off-hook transients and impedance changes – is provided. For POTS voiceband service, the low-pass filters provide protection from ADSL signals which may impact, through non-linear or other effects, remote devices (handset, fax, voiceband, modem, etc.) and central office operation. This filtering should be performed while maintaining the quality of the end-to-end voiceband connection (i.e. between the POTS and PSTN interfaces). + +Likewise, the ISDN-BA splitter is also twofold. + +#### E.1 Type 1 – European + +##### E.1.1 Impedance matching + +The European harmonized matching impedance, $Z_{\text{complex}(1)}$ , for non-voice terminals (e.g. voiceband modems). This compromise impedance is detailed more fully in Recommendation Q.552. + +Different three-element compromise impedances are used for voice terminal operation in different countries. The text below details the reference impedances and any other country specific parameters. Component values are $\pm 0.1\%$ unless otherwise stated. + +###### E.1.1.1 European harmonized – Non-voice terminals + +$$Z_{\text{complex}(1)} = 150 \text{ nF} // 750 \Omega + 270 \Omega$$ + +###### E.1.1.2 Voice terminals + +$$Z_{\text{complex}(1)} = 150 \text{ nF} // 750 \Omega + 270 \Omega$$ + +$$Z_{\text{complex}(2)} = 230 \text{ nF} // 1050 \Omega + 320 \Omega$$ + +$$Z_{\text{complex}(3)} = 115 \text{ nF} // 820 \Omega + 220 \Omega$$ + +$$Z_{\text{real}(1)} = 600 \Omega$$ + +$$Z_{\text{real}(1)} = 800 \Omega$$ + +##### E.1.2 Return loss + +TELE port and LINE port return loss against $Z_{\text{complex}(n)}$ or $Z_{\text{real}(n)}$ when the other port is terminated in $Z_{\text{complex}(n)}$ or $Z_{\text{real}(n)}$ shall be as shown in Figure E.1. + +![Figure E.1/G.992.1: Minimum value of return loss against the test network for the exchange impedance at a 2-wire interface. The graph shows Return loss (dB) on the y-axis (14 to 18) versus Frequency (log f) on the x-axis (300 to 3400 Hz). The return loss is 14 dB at 300 Hz, rises to 18 dB at 500 Hz, remains at 18 dB until 2000 Hz, and then drops back to 14 dB at 3400 Hz. A shaded region indicates the minimum value of return loss.](8573f4d40ce07a99156c50e3b8aed550_img.jpg) + +T1532940-99 + +Figure E.1/G.992.1: Minimum value of return loss against the test network for the exchange impedance at a 2-wire interface. The graph shows Return loss (dB) on the y-axis (14 to 18) versus Frequency (log f) on the x-axis (300 to 3400 Hz). The return loss is 14 dB at 300 Hz, rises to 18 dB at 500 Hz, remains at 18 dB until 2000 Hz, and then drops back to 14 dB at 3400 Hz. A shaded region indicates the minimum value of return loss. + +**Figure E.1/G.992.1 – Minimum value of return loss against the test network for the exchange impedance at a 2-wire interface** + +### E.1.3 Insertion loss + +TELE port to LINE port insertion loss shall be $< 1$ dB at 1 kHz for $Z_{\text{complex(n)}}$ + +TELE port to LINE port insertion loss shall be $< 0.3$ dB at 1 kHz for $Z_{\text{real(n)}}$ + +### E.1.4 Insertion loss distortion + +Insertion loss distortion 200-4000 Hz $< \pm 1$ dB      term = $Z_{\text{complex(n)}}$ + +### E.1.5 Isolation + +Isolation resistance, branch-earth $> 10$ M $\Omega$      term = $\infty \Omega$ ; 100 V DC + +Isolation resistance, branch-branch $> 1$ M $\Omega$      term = $\infty \Omega$ ; 100 V DC + +DC resistance $< 50 \Omega$      term = $0 \Omega$ . + +### E.1.6 Signal power + +Maximum peak signal power in 200-4000 Hz $< 3$ dBm ETS-300.001 § 4.4.2 on 600 $\Omega$ + +Loop current $< 100$ mA + +### E.1.7 Ringing + +Ringing frequency 25-50 Hz + +Ringing AC $< 100$ Vrms + +Ringing DC (AC superimposed on DC) $< 100$ V + +### E.1.8 Unbalance about Earth (ETS-300.001, § 4.2.1 and § 4.2.2) + +LCL (test method Recommendation G.117, subclause 4.1.3) + +TCL (test method Recommendation G.117, subclause 4.1.3) + +15-50 Hz $> 40$ dB terminated with 600 $\Omega$ + +50-600 Hz $> 46$ dB terminated with 600 $\Omega$ + +600-3400 Hz $> 52$ dB terminated with 600 $\Omega$ + +### **E.1.9 Frequencies and levels for pulse metering (ETS-300.001, § 1.7.8)** + +| | | +|----------------|----------------------------------------| +| Frequency | 12/16 kHz $\pm 1\%$ | +| Insertion loss | $< 3$ dB in 200 $\Omega$ | +| Maximum level | $< 5$ V rms in 200 $\Omega$ | + +## **E.2 Type 2 – North America** + +### **E.2.1 Introduction** + +This subclause contains specifications for a POTS splitter appropriate to North America. The requirements contained in E.2 shall be met for a POTS splitter designed for deployment in North America. The purpose of the low-pass filters is twofold. For ADSL signals, protection from the high-frequency transients and impedance effects that occur during POTS operation – ringing transients, ring trip transients, and off-hook transients and impedance changes – is provided. For POTS voiceband service, the low-pass filters provide protection from ADSL signals which may impact, through non-linear or other effects, remote devices (handset, fax, voiceband, modem, etc.) and central office operation. This filtering should be performed while maintaining the quality of the end-to-end – that is, between the POTS and PSTN interfaces of Figure E.5 – Voiceband connection. + +#### **E.2.1.1 POTS splitter function location** + +Two POTS splitter functions are defined; one for the remote (R) end and one for the central office (CO) end. The function can be implemented either internally to the ATU-x modem or externally. In either case, all functions specified are required (exception is maintenance test signatures, see E.2.1.7). + +In Figure E.2, the capacitors are shown as 0.12 $\mu\text{F}$ . These capacitors are for DC blocking. They work in concert with the input to the modem's HPF function and are to be included in the input impedance calculation of the modem. This point is not available for inspection when the CO splitter function is provided internally to the modem and, therefore, the capacitors do not appear explicitly. The DC blocking function is, however, provided in the normal HPF function. This difference is taken into account in the test setups in this annex. + +In a case where some or all of the HPF function are incorporated in the external CO POTS splitter, the 0.12 $\mu\text{F}$ capacitors do not appear since the DC blocking will be included in the HPF function. Incorporating some or all of the HPF in the CO POTS splitter is for further study. + +#### **E.2.1.2 Frequencies used in testing** + +Two bands of frequencies are used for testing: + +- Voiceband (VB) frequencies are from 0-4 kHz. +- ADSL Band frequencies are from 30-1104 kHz. + +Testing is not performed between 4-30 kHz but it is expected that the LPF will be well behaved in that area. + +All external POTS splitters with LPF or LPF/HPF included shall meet specifications between 30 and 1104 kHz. + +Not all integral modem designs are intended to occupy the full spectrum between 30 and 1104 kHz. In each implementation, testing may be performed only on the utilized frequency band. The vendor in literature and in each test report shall explicitly state the band of frequencies used in testing each modem. + +### E.2.1.3 Balanced terminations + +All testing is done in a BALANCED (i.e. metallic) method. One end of some setups may contain an unbalanced connection to facilitate testing methodology if the resultant measurement maintains balance. + +### E.2.1.4 Single ended testing + +Single ended testing is performed on each POTS splitter function. Specifications contained in this annex are written for single splitter functions, not end-to-end. Compliance with this annex does NOT guarantee end-to-end performance since the modems are not included in this annex testing. + +### E.2.1.5 POTS splitter functions + +The external central office POTS splitter may be mounted some distance from the ATU-C modem. To protect from DC faults, DC blocking capacitors shall be included on the xDSL port of the POTS Splitter. These capacitors form part of the input to the xDSL HPF function and must be included in calculations of that input impedance (approximately 20-34 nF). If the POTS splitter function is included entirely within the modem, the capacitors shall be included as part of the HPF function. See Figure E.2. + +![Schematic diagram of an external POTS central office splitter without HPF function. The diagram shows three ports: xDSL Port, PSTN, and Line Port. The xDSL Port is connected to two 0.12 µF capacitors in series. The PSTN port is connected to a block labeled 'SIG' (Signal) which is connected to a block labeled 'LPF' (Low Pass Filter). The LPF output is connected to the Line Port. The xDSL Port is also connected to the Line Port. The diagram is labeled T1532950-99.](1167027feef0c2e7665ac41e9b12f6b3_img.jpg) + +The diagram illustrates an external POTS central office splitter without an HPF function. It features three main ports: an xDSL Port at the top, a PSTN port on the left, and a Line Port at the bottom right. The xDSL Port is connected to two 0.12 µF capacitors in series, which are then connected to the Line Port. The PSTN port is connected to a block labeled 'SIG' (Signal), which is in turn connected to a block labeled 'LPF' (Low Pass Filter). The LPF output is connected to the Line Port. The xDSL Port is also connected to the Line Port. The diagram is labeled T1532950-99. + +Schematic diagram of an external POTS central office splitter without HPF function. The diagram shows three ports: xDSL Port, PSTN, and Line Port. The xDSL Port is connected to two 0.12 µF capacitors in series. The PSTN port is connected to a block labeled 'SIG' (Signal) which is connected to a block labeled 'LPF' (Low Pass Filter). The LPF output is connected to the Line Port. The xDSL Port is also connected to the Line Port. The diagram is labeled T1532950-99. + +Figure E.2/G.992.1 – External POTS central office splitter without HPF function + +The DC blocking capacitors are for the external POTS splitter, without the HPF function, only. Internal splitter function or external splitters with a complete HPF function may incorporate this capacitance in the input to the HPF function. The DC blocking capacitors are optional on splitters integrated within the equipment closely associated with the ATU-C. See Figure E.3. + +![Schematic diagram of an external POTS remote splitter. The diagram shows three ports: Line Port, xDSL Port, and POTS. The Line Port is connected to a block labeled 'LPF' (Low Pass Filter). The LPF output is connected to a block labeled 'SIG' (Signal), which is then connected to the xDSL Port. The LPF output is also connected to the POTS port. The diagram is labeled T1532960-99.](4cffd2caac57799e062fd4d4674b4f4c_img.jpg) + +The diagram illustrates an external POTS remote splitter. It features three main ports: a Line Port at the bottom left, an xDSL Port at the top right, and a POTS port at the bottom right. The Line Port is connected to a block labeled 'LPF' (Low Pass Filter). The LPF output is connected to a block labeled 'SIG' (Signal), which is then connected to the xDSL Port. The LPF output is also connected to the POTS port. The diagram is labeled T1532960-99. + +Schematic diagram of an external POTS remote splitter. The diagram shows three ports: Line Port, xDSL Port, and POTS. The Line Port is connected to a block labeled 'LPF' (Low Pass Filter). The LPF output is connected to a block labeled 'SIG' (Signal), which is then connected to the xDSL Port. The LPF output is also connected to the POTS port. The diagram is labeled T1532960-99. + +Figure E.3/G.992.1 – External POTS remote splitter + +### E.2.1.6 ZHP defined + +To facilitate testing of the POTS splitter independently of the actual modem or specific vendor, two ZHPs are defined in Figure E.4 to allow proper termination of the xDSL port during voiceband testing. The ZHP is valid only for voiceband frequencies. The combination of capacitors in the ZHP-r is only representative. The input shall be 27 nF, however derived. + +![Figure E.4/G.992.1 – ZHP definitions. The diagram shows two circuit models for Zero Handoff Point (ZHP) definitions. The left circuit, labeled 'ZHP for External Central Office splitter', consists of two 0.10 μF capacitors in series with a parallel combination of a 100 ohms resistor and a 0.47 mH inductor. The right circuit, labeled 'ZHP Remote end', consists of two 0.10 μF capacitors in series with two 0.12 μF capacitors in series, followed by a parallel combination of a 100 ohms resistor and a 0.47 mH inductor. A reference code T1532970-99 is present.](3eb2c6bfde13eae0df07b28c24d52e5d_img.jpg) + +Figure E.4/G.992.1 – ZHP definitions. The diagram shows two circuit models for Zero Handoff Point (ZHP) definitions. The left circuit, labeled 'ZHP for External Central Office splitter', consists of two 0.10 μF capacitors in series with a parallel combination of a 100 ohms resistor and a 0.47 mH inductor. The right circuit, labeled 'ZHP Remote end', consists of two 0.10 μF capacitors in series with two 0.12 μF capacitors in series, followed by a parallel combination of a 100 ohms resistor and a 0.47 mH inductor. A reference code T1532970-99 is present. + +NOTE – Component Tolerances: Capacitors: 2.5%, Resistors: 1%, Coils: 5%. + +**Figure E.4/G.992.1 – ZHP definitions** + +### E.2.1.7 Maintenance test signatures + +If the maintenance test signatures are provided, they shall be as shown in Figure E.5. + +In order to allow the POTS splitter to be managed by the network operational support systems and to be identified by metallic loop test systems, the POTS splitter function may contain signatures that are activated only by the metallic test systems. The signatures are unique for ADSL and are different for each end of the loop. All central office end POTS splitters shall have the same signature and all remote end POTS splitters shall have the same signature. The signatures are designed to be active only during the maintenance test mode and will not interfere with normal operation of the circuit. The signatures are located on the POTS/PSTN side of the LPF function, protecting the ADSL band frequencies from the non-linear effects of the diodes. The signatures are defined in Figure E.5. + +![Figure E.5/G.992.1 – Maintenance test signatures. The diagram shows two circuit models for maintenance test signatures. The left circuit, labeled 'CO splitter signature', shows a series combination of a 1N4007 diode, a 36 V 10% Zener diode, and a 110 K 1% resistor connected between terminals T and R. The right circuit, labeled 'Remote splitter signature', shows a series combination of a 0.47 μF 10% capacitor, a 6.8 V 10% Zener diode, and a 33 K 1% resistor connected between terminals T and R. A reference code T1532980-99 is present.](d9edf1a1fe1c6cd907639ca3b39627e1_img.jpg) + +Figure E.5/G.992.1 – Maintenance test signatures. The diagram shows two circuit models for maintenance test signatures. The left circuit, labeled 'CO splitter signature', shows a series combination of a 1N4007 diode, a 36 V 10% Zener diode, and a 110 K 1% resistor connected between terminals T and R. The right circuit, labeled 'Remote splitter signature', shows a series combination of a 0.47 μF 10% capacitor, a 6.8 V 10% Zener diode, and a 33 K 1% resistor connected between terminals T and R. A reference code T1532980-99 is present. + +**Figure E.5/G.992.1 – Maintenance test signatures** + +## E.2.2 DC characteristics + +All requirements shall be met in the presence of all POTS loop currents from 0 mA to 100 mA. The low-pass filter shall pass POTS tip-to-ring DC voltages of 0 V to minus 60 V DC and ringing signals no larger than 103 Vrms superimposed on the DC signal at any frequency from 20 to 30 Hz. + +The DC resistance from tip-to-ring at the PSTN interface with the U-C interface shorted, or at the POTS interface with the U-R interface shorted, shall be less than or equal to 25 Ω. The DC resistance from tip to ground and from ring to ground at the PSTN interface with the U-C interface open, or at the POTS interface with the U-R interface open, shall be greater than or equal to 5 MΩ. + +## E.2.3 Voiceband characteristics + +### E.2.3.1 Metallic balanced (differential mode) + +#### E.2.3.1.1 Test loops + +Loops to be used for testing are divided into two groups. This is done to obtain more specific requirements under the widely varying conditions of short and long loops and to account for the effect of the opposite splitter impedances being "seen" through the loop and affecting performance. + +- Short loops: 0, 152 m (0.5 kft), 619 m (2.0 kft), 1520 m (5 kft) pairs of 26 AWG cables. +- Long loops: resistance design loops T #7, T #9, and T #13 and loops C #4, C #6, C #7 and C #8. + +NOTE – Test loops are defined in Recommendation G.996.1. + +#### E.2.3.1.2 Insertion loss at 1004 Hz + +For each of the test loops specified in E.2.3.1.1, and using the test setup shown in Figures E.6 and E.7, the insertion loss from the source to the termination shall be measured with and without the splitter/ZHP combination inserted. + +The increase in insertion loss at 1004 Hz on any of the test loops, due to the addition of the splitter/ZHP, shall be less than specified in Table E.1. + +**Table E.1/G.992.1 – Loss due to addition of splitter/ZHP** + +| Description | Loss | +|----------------------------------|------------------| +| Short loop, ZTc = 900, ZTr = 600 | < 1.0 dB CO end | +| Long loop, ZTc = 900, ZTr = 600 | < 0.75 dB CO end | +| Short loop, ZTc = 900, ZTr = 600 | < 1.0 dB R end | +| Long loop, ZTc = 900, ZTr = 600 | < 0.75 dB R end | + +#### E.2.3.1.3 Attenuation distortion in the voiceband + +The variation of insertion loss with frequency shall be measured using the test setup in Figures E.6 and E.7. The defined ZHP will be attached to the xDSL port of the splitter. If the splitter is an internal part of the ATU, then the modem remains attached as the xDSL load. The increase in attenuation distortion, relative to the 1004 Hz insertion loss, caused by the POTS splitter with the ZHP (or modem) load attached using each of the test loops identified above, shall be less than that specified in Table E.2. + +**Table E.2/G.992.1 – Increase in attenuation distortion caused by POTS splitter** + +| Description | Loss (Note) | | +|-------------------------------------------------------------------|--------------|--------------| +| | 0.2-3.4 kHz | 3.4-4.0 kHz | +| Short loop, CO splitter, ZTc = 900, ZTr = 600 | +1.5 to -1.5 | +2.0 to -2.0 | +| Long loop, CO splitter, ZTc = 900, ZTr = 600 | +0.5 to -1.5 | +1.0 to -1.5 | +| Short loop, R splitter, ZTc = 900, ZTr = 600 | +1.5 to -1.5 | +2.0 to -2.0 | +| Long loop, R splitter, ZTc = 900, ZTr = 600 | +0.5 to -1.5 | +1.0 to -1.5 | +| NOTE – Attenuation is a positive value, gain is a negative value. | | | + +Figure E.6 defines the test configuration and the value of the test components that shall be used for transmission measurements in the voiceband for the central office POTS splitter. + +![Schematic diagram of transmission measurements in voiceband for the central office splitter. The diagram shows a test setup with PSTN, U-C, and U-R interfaces. On the left, a ZTc (900 Ω) termination is connected to Test Equipment, which is connected to the PSTN interface of a CO POTS Splitter. The CO POTS Splitter contains a Switch (S, I, G) and a Low Pass Filter (LPF). A 0.12 µF capacitor is connected between the LPF output and the xDSL interface. The xDSL interface is connected to a ZHP-c (load). The LPF output is also connected to the U-C interface, which is connected to a Test Loop, which is then connected to a ZTr (600 Ω) termination at the U-R interface.](841943891f19fcd045f406339e8d5655_img.jpg) + +Schematic diagram of transmission measurements in voiceband for the central office splitter. The diagram shows a test setup with PSTN, U-C, and U-R interfaces. On the left, a ZTc (900 Ω) termination is connected to Test Equipment, which is connected to the PSTN interface of a CO POTS Splitter. The CO POTS Splitter contains a Switch (S, I, G) and a Low Pass Filter (LPF). A 0.12 µF capacitor is connected between the LPF output and the xDSL interface. The xDSL interface is connected to a ZHP-c (load). The LPF output is also connected to the U-C interface, which is connected to a Test Loop, which is then connected to a ZTr (600 Ω) termination at the U-R interface. + +ZHP-c = the impedance presented to the POTS connection by an ATU-C through the capacitance of the POTS splitter DC blocking capacitors + +NOTE – The DC blocking capacitors are only for the external POTS splitter without the HPF function. Internal splitter function or external splitters with a complete HPF function may incorporate this capacitance in the input to the HPF function. + +**Figure E.6/G.992.1 – Transmission measurements in voiceband for the central office splitter** + +Figure E.7 defines the test configuration and the value of the test components that shall be used for transmission measurements in the voiceband for the remote POTS splitter. + +![Block diagram of the test configuration for transmission measurements in the voiceband for the remote POTS splitter. The diagram shows a 'Test Loop' connected between 'U-C' and 'U-R' interfaces. At the 'U-R' interface, the loop connects to a 'Remote POTS Splitter'. The splitter has two outputs: one labeled 'LPF' (Low Pass Filter) which leads to the 'POTS' interface, and another labeled 'xDSL' which connects to a 'ZHP-r (load)'. The 'POTS' interface is connected to 'Test Equipment', which is then connected to a 'ZTr (600 ohms)' termination. A note indicates 'ZTr is the Normal Termination in Test Set'. On the 'U-C' side, a 'ZTc (900 ohms)' termination is shown. A reference code 'T1533000-99' is present in the bottom right of the diagram area.](b533d1084262104aa731c9b933f362a4_img.jpg) + +Block diagram of the test configuration for transmission measurements in the voiceband for the remote POTS splitter. The diagram shows a 'Test Loop' connected between 'U-C' and 'U-R' interfaces. At the 'U-R' interface, the loop connects to a 'Remote POTS Splitter'. The splitter has two outputs: one labeled 'LPF' (Low Pass Filter) which leads to the 'POTS' interface, and another labeled 'xDSL' which connects to a 'ZHP-r (load)'. The 'POTS' interface is connected to 'Test Equipment', which is then connected to a 'ZTr (600 ohms)' termination. A note indicates 'ZTr is the Normal Termination in Test Set'. On the 'U-C' side, a 'ZTc (900 ohms)' termination is shown. A reference code 'T1533000-99' is present in the bottom right of the diagram area. + +ZTc = 900 Ω + +ZTr = 600 Ω + +ZHP-r = the impedance presented to the POTS connection by an ATU-R + +**Figure E.7/G.992.1 – Transmission measurements in voiceband for the remote POTS splitter=** + +#### E.2.3.1.4 Delay distortion + +The delay distortion of the POTS splitter shall be measured using Figures E.6 and E.7. The increase in delay distortion caused by the POTS splitter in each of the test loops shall be less than that specified in Table E.3. + +**Table E.3/G.992.1 – Increase in delay distortion caused by POTS splitter** + +| Description | Delay distortion | | +|-----------------------------------------------|------------------|-------------| +| | 0.6-3.2 kHz | 0.2-4.0 kHz | +| Short loop, CO splitter, ZTc = 900, ZTr = 600 | 200 µs | 250 µs | +| Long loop, CO splitter, ZTc = 900, ZTr = 600 | 200 µs | 250 µs | +| Short loop, R splitter, ZTc = 900, ZTr = 600 | 200 µs | 250 µs | +| Long loop, R splitter, ZTc = 900, ZTr = 600 | 200 µs | 250 µs | + +#### E.2.3.1.5 Return loss + +Figures E.8 and E.9 define the test configuration and the value of the test components that shall be used for impedance measurements in the voiceband for both the central office and remote POTS splitter units. + +![Figure E.8/G.992.1 – CO POTS splitter return loss setup. The diagram shows a 'Test Equipment' connected to a 'POTS Splitter at CO'. The splitter contains 'SIG' and 'LPF' components. A 'ZNL-c' (Return loss reference impedance) is connected to the 'PSTN' side. The 'xDSL' side of the splitter is connected to a 'Real Cable', which is terminated with a '600 ohms' load. A '0.12 µF' capacitor (used only at CO termination) and a 'ZHP-c' impedance are also shown on the xDSL side. Vertical dashed lines mark the 'PSTN', 'U-C', and 'xDSL' interfaces. A label 'T1533010-99' is present.](fd4b2ee19b709bcb11190893e23f8453_img.jpg) + +Figure E.8/G.992.1 – CO POTS splitter return loss setup. The diagram shows a 'Test Equipment' connected to a 'POTS Splitter at CO'. The splitter contains 'SIG' and 'LPF' components. A 'ZNL-c' (Return loss reference impedance) is connected to the 'PSTN' side. The 'xDSL' side of the splitter is connected to a 'Real Cable', which is terminated with a '600 ohms' load. A '0.12 µF' capacitor (used only at CO termination) and a 'ZHP-c' impedance are also shown on the xDSL side. Vertical dashed lines mark the 'PSTN', 'U-C', and 'xDSL' interfaces. A label 'T1533010-99' is present. + +**Figure E.8/G.992.1 – CO POTS splitter return loss setup** + +![Figure E.9/G.992.1 – Remote POTS splitter return loss setup. The diagram shows a 'Test Equipment' connected to a 'Remote POTS Splitter'. The splitter contains 'LPF' and 'SIG' components. A 'ZHP-r' impedance is connected to the 'xDSL' side. The 'POTS' side of the splitter is connected to a 'Real Cable', which is terminated with a '900 ohms + 2.16 µF' load. A 'ZNL-r' (Return loss reference impedance) is connected to the 'Test Equipment'. Vertical dashed lines mark the 'U-R' and 'POTS' interfaces. A label 'T1533020-99' is present.](add5c678c1d8eedc51d3e8f86ca21e3a_img.jpg) + +Figure E.9/G.992.1 – Remote POTS splitter return loss setup. The diagram shows a 'Test Equipment' connected to a 'Remote POTS Splitter'. The splitter contains 'LPF' and 'SIG' components. A 'ZHP-r' impedance is connected to the 'xDSL' side. The 'POTS' side of the splitter is connected to a 'Real Cable', which is terminated with a '900 ohms + 2.16 µF' load. A 'ZNL-r' (Return loss reference impedance) is connected to the 'Test Equipment'. Vertical dashed lines mark the 'U-R' and 'POTS' interfaces. A label 'T1533020-99' is present. + +**Figure E.9/G.992.1 – Remote POTS splitter return loss setup** + +ZNL-c (see Note 2) = 800 Ω in parallel with the series connection of a 100 Ω resistor and a 50 nF capacitor (long loop model seen from CO) + +ZNL-r (see Note 2) = 1330 Ω in parallel with the series connection of a 348 Ω resistor and a 100 nF capacitor (long loop model seen from RT) + +ZHP-c = the impedance presented to the POTS connection by an ATU-C through the capacitance of the POTS splitter DC blocking capacitors + +ZHP-r = the impedance presented to the POTS connection by an ATU-R + +NOTE 1 – The DC blocking capacitors are for the external POTS splitter without the HPF function only. Internal splitter function or external splitters with a complete HPF function may incorporate this capacitance in the input to the HPF function. + +NOTE 2 – This value comes from the Bellcore LSSGR as a reference compromise impedance for non-loaded cable. + +The return loss of each splitter under the specified conditions, either with or without the ZHP attached, shall be greater than the values specified in Table E.4. + +**Table E.4/G.992.1 – Splitter return loss** + +| Description | Zref | Zterm
(\Omega) | ERL
(dB) | SRL-L
(dB) | SRL-H
(dB) | Comments | +|----------------------------------------------------------------------|-------------|----------------------------------------|---------------------|-----------------------|-----------------------|-----------------| +| CO splitter | ZNL-c | 600 | 8 | 5 | 5 | | +| CO splitter | ZNL-c | 600 | N/A | N/A | 2 | Single freq. | +| RT splitter | ZNL-r | 900 | 6 | 5 | 3 | | +| RT splitter | ZNL-r | 900 | N/A | N/A | 2 | Single freq. | +| NOTE – Individual frequencies start at 2200 Hz and sweep to 3400 Hz. | | | | | | | + +#### **E.2.3.1.6 Distortion** + +The distortion contributed by the low-pass filter shall be measured using the test configuration of Figures E.6 and E.7 and the null loop. + +With an applied 4-tone set, at a level of –9 dBm, the second and third order intermodulation distortion products shall be at least 57 dB and 60 dB, respectively, below the received signal level. + +#### **E.2.3.2 Longitudinal balance of POTS splitter** + +The longitudinal balance of the POTS splitter can be measured using two different techniques. One technique is to treat the POTS splitter as a separate entity which requires using the 2 PORT testing technique. The other technique is to test the CO splitter containing the POTS splitter, ATU-C and CO line card combination as a one port network. This one port network would require using the 1 PORT testing technique. + +##### **E.2.3.2.1 Longitudinal balance of POTS splitter using 2 PORT testing technique** + +This method shall be used to test a POTS splitter when it is treated as a separate entity. + +The longitudinal balance of the POTS splitter (without loops), measured in either direction between the POTS/PSTN and line port, as a two-port device, shall be measured in accordance with the latest North American measurement practices. In the case where DC blocking capacitors are included as part of the splitter function on the xDSL port, the xDSL port shall be shorted. Otherwise, the xDSL port shall be open. Because of the maintenance signatures, the applied longitudinal voltage shall be maximum 3.0 V p-p. The balance shall be greater than 58 dB for frequencies between 200 Hz-1 kHz with a straight line level decreasing to 53 dB at 3 kHz. A DC bias current of 25 mA will be applied. + +The termination of the test set is set for series-balance measurement per the latest North American measurement practices. Prior to testing, a test circuit balance (calibration) of 77 dB (58 + 19 dB) will be achieved to ensure 1 dB accuracy. + +Figure E.10 shows the test setup for the external CO POTS splitter. The xDSL port is shorted. If testing longitudinal balance on an integrated CO modem, the ATU-C shall be connected but powered down. + +Figure E.11 shows the test setup for the external remote POTS splitter. + +![Figure E.10/G.992.1 – Longitudinal balance CO test setup. This schematic diagram shows a CO line card connected to a PSTN. The PSTN is represented by a box containing 'SIG' and 'LPF' blocks. The 'SIG' block is connected to an 'LB Test Source'. The 'LPF' block is connected to a 'Line Port'. The 'Line Port' is connected to an 'LB Test Load'. Above the PSTN box, an 'xDSL Port' is shown. Two capacitors, each labeled '0.12 μF', are connected between the 'xDSL Port' and the 'Line Port'. The 'xDSL Port' is also connected to a 'Shorted' loop.](978794771205b002dd72295a59de7919_img.jpg) + +Figure E.10/G.992.1 – Longitudinal balance CO test setup. This schematic diagram shows a CO line card connected to a PSTN. The PSTN is represented by a box containing 'SIG' and 'LPF' blocks. The 'SIG' block is connected to an 'LB Test Source'. The 'LPF' block is connected to a 'Line Port'. The 'Line Port' is connected to an 'LB Test Load'. Above the PSTN box, an 'xDSL Port' is shown. Two capacitors, each labeled '0.12 μF', are connected between the 'xDSL Port' and the 'Line Port'. The 'xDSL Port' is also connected to a 'Shorted' loop. + +T1533030-99 + +**Figure E.10/G.992.1 – Longitudinal balance CO test setup** + +![Figure E.11/G.992.1 – Longitudinal balance remote test setup. This schematic diagram shows a remote test setup. On the left, an 'LB Test Load' is connected to a 'Line Port'. The 'Line Port' is connected to a box containing 'LPF' and 'SIG' blocks. The 'SIG' block is connected to a 'POTS' block. The 'POTS' block is connected to an 'LB Test Source'. Above the box, an 'xDSL Port' is shown. The 'xDSL Port' is connected to the 'Line Port' via two capacitors, each labeled '0.12 μF'.](5cdc04ba574b7b819a3cb6dbbd91306c_img.jpg) + +Figure E.11/G.992.1 – Longitudinal balance remote test setup. This schematic diagram shows a remote test setup. On the left, an 'LB Test Load' is connected to a 'Line Port'. The 'Line Port' is connected to a box containing 'LPF' and 'SIG' blocks. The 'SIG' block is connected to a 'POTS' block. The 'POTS' block is connected to an 'LB Test Source'. Above the box, an 'xDSL Port' is shown. The 'xDSL Port' is connected to the 'Line Port' via two capacitors, each labeled '0.12 μF'. + +T1533040-99 + +**Figure E.11/G.992.1 – Longitudinal balance remote test setup** + +#### E.2.3.2.2 Longitudinal balance of POTS splitter using 1 PORT testing technique + +This method shall be used to test a CO splitter when the POTS splitter, ATU-C and CO line card combination is treated as a one port network. + +The longitudinal balance of the combined POTS splitter, ATU-C and CO line card (without loops) shall be measured in accordance with the latest North American measurement practices. Because of the maintenance signatures, the applied longitudinal voltage shall be maximum 3.0 V p-p. The balance shall be greater than 52 dB for frequencies between 200 Hz-3.2 kHz. A DC POTS load to generate a bias current of 25 mA will be used. + +Prior to testing, a test circuit balance (calibration) of 71 dB (52 + 19 dB) will be achieved to ensure 1 dB accuracy. + +Figure E.12 shows the test setup for the POTS splitter, ATU-C and CO line card combination one port network. + +![Figure E.12/G.992.1 – Longitudinal balance CO test setup for 1 PORT networks. This schematic diagram shows a test setup for a one-port network. On the left, an 'ATU-C' and a 'CO Line Card' are connected to a box containing 'SIG' and 'LPF' blocks. The 'SIG' block is connected to the 'ATU-C'. The 'LPF' block is connected to a 'Line Port'. The 'Line Port' is connected to an 'LB Test Source'. Above the box, an 'xDSL Port' is shown. The 'xDSL Port' is connected to the 'Line Port' via two capacitors, each labeled '0.12 μF'.](1438af26f60e782d6bbf1503ef3ee04d_img.jpg) + +Figure E.12/G.992.1 – Longitudinal balance CO test setup for 1 PORT networks. This schematic diagram shows a test setup for a one-port network. On the left, an 'ATU-C' and a 'CO Line Card' are connected to a box containing 'SIG' and 'LPF' blocks. The 'SIG' block is connected to the 'ATU-C'. The 'LPF' block is connected to a 'Line Port'. The 'Line Port' is connected to an 'LB Test Source'. Above the box, an 'xDSL Port' is shown. The 'xDSL Port' is connected to the 'Line Port' via two capacitors, each labeled '0.12 μF'. + +T1533050-99 + +**Figure E.12/G.992.1 – Longitudinal balance CO test setup for 1 PORT networks** + +### E.2.3.3 Transparent testing capacitance + +To allow the current metallic test systems to continue to test with current test capabilities, an input impedance is defined for a special, narrow-frequency band. + +#### E.2.3.3.1 Tip to ring capacitance + +The intent of this requirement is to limit the maximum capacitance seen by metallic line testing systems. By setting this limit, the metallic test systems can still test POTS services with the accuracy and dependability they have today. + +Overall, the admittance of the POTS or PSTN port shall be capacitive. + +The capacitance present at either the POTS or PSTN interfaces in the frequency range of 20-30 Hz shall be a maximum of 300 nF. This amount includes the capacitance of the two POTS splitters with attached modems. + +The following, per end, maximum/minimum measurements as shown in Figure E.13 shall be met: + +- POTS splitter, either CO or remote without the modem connected: + - 115 nF Max. + - 20 nF Min. +- Modem input allowance, including the DC blocking capacitors at the CO end: + - 35 nF Max. + - 20 nF Min. +- Modem with integral POTS splitter function or – external POTS splitter with both HPF and LPF functions, are the sum of the above: + - 150 nF Max. + - 40 nF Min. + +![Figure E.13/G.992.1 – Capacitance test diagram. The diagram shows a Line Port on the left connected to a box containing an LPF (Low Pass Filter) and a POTS splitter. The POTS splitter has two outputs: one labeled 'xDSL Port' and another labeled 'POTS'. An arrow labeled 'Capacitance' points to the POTS output. The diagram is labeled 'T1533060-99' at the bottom right.](dd2ddef02cef83a06acfc3e710b36564_img.jpg) + +The diagram illustrates a test setup for capacitance measurement. A 'Line Port' enters from the left and connects to a rectangular box. Inside this box, the line first passes through a sub-box labeled 'LPF'. After the LPF, the line connects to another sub-box representing a POTS splitter, which contains the letters 'S', 'I', and 'G' stacked vertically. From the POTS splitter, one output line extends to the right, labeled 'xDSL Port', and another output line extends further right, labeled 'POTS'. An arrow labeled 'Capacitance' points to the 'POTS' output line. The entire diagram is enclosed in a larger rectangular frame. At the bottom right of the frame, the text 'T1533060-99' is present. + +Figure E.13/G.992.1 – Capacitance test diagram. The diagram shows a Line Port on the left connected to a box containing an LPF (Low Pass Filter) and a POTS splitter. The POTS splitter has two outputs: one labeled 'xDSL Port' and another labeled 'POTS'. An arrow labeled 'Capacitance' points to the POTS output. The diagram is labeled 'T1533060-99' at the bottom right. + +Figure E.13/G.992.1 – Capacitance test + +#### E.2.3.3.2 Capacitance to ground + +There should be no designed AC path to ground. In order to maintain the ability to test accurately, the maximum stray capacitance to ground from either leg of the POTS splitter shall be less than 1.0 nF. + +### E.2.4 ADSL band testing + +#### E.2.4.1 ADSL band attenuation + +The insertion loss of the low-pass filter and ZHP (i.e. the difference in attenuation measured with and without the filter) measured as shown in Figures E.14 and E.15 shall be greater than 65 dB from 32 to 300 kHz and 55 dB from 300 to 1104 kHz with an input level of 10 dBm. + +![Figure E.14/G.992.1 – Measurement of the CO splitter attenuation in the ADSL band. The diagram shows an 'External CO POTS splitter without HPF'. On the left, an 'xDSL Port' is connected to a 'ZHP-c' device. The 'PSTN' port is connected to a voltage source 'Vm' with a 'Hi Z' input and a '900 ohms' load. The 'Line Port' is connected to a voltage source 'Z' with a 'Source 100 ohms', '30 kHz-1104 kHz', 'balanced' signal. Inside the splitter, there are two '0.12 µF' capacitors on the xDSL lines and an 'LPF' (Low Pass Filter) on the PSTN line. A label 'T1533070-99' is present.](bae1bd2b5dec0c7f0717e710ad5a3412_img.jpg) + +Figure E.14/G.992.1 – Measurement of the CO splitter attenuation in the ADSL band. The diagram shows an 'External CO POTS splitter without HPF'. On the left, an 'xDSL Port' is connected to a 'ZHP-c' device. The 'PSTN' port is connected to a voltage source 'Vm' with a 'Hi Z' input and a '900 ohms' load. The 'Line Port' is connected to a voltage source 'Z' with a 'Source 100 ohms', '30 kHz-1104 kHz', 'balanced' signal. Inside the splitter, there are two '0.12 µF' capacitors on the xDSL lines and an 'LPF' (Low Pass Filter) on the PSTN line. A label 'T1533070-99' is present. + +**Figure E.14/G.992.1 – Measurement of the CO splitter attenuation in the ADSL band** + +![Figure E.15/G.992.1 – Measurement of the remote splitter attenuation in the ADSL band. The diagram shows a 'Remote POTS splitter'. On the left, a voltage source 'Z' with a 'Source 100 ohms', '30 kHz-1104 kHz', 'balanced' signal is connected to the 'Line Port'. The 'xDSL Port' is connected to a 'ZHP-r' device. The 'POTS' port is connected to a voltage source 'Vm' with a '600 ohms' load and a 'Hi Z' input. Inside the splitter, there is an 'LPF' (Low Pass Filter) on the line and 'SIG' (Signal) components on the xDSL lines. A label 'T1533080-99' is present.](58998c9d67656e95221338204f251872_img.jpg) + +Figure E.15/G.992.1 – Measurement of the remote splitter attenuation in the ADSL band. The diagram shows a 'Remote POTS splitter'. On the left, a voltage source 'Z' with a 'Source 100 ohms', '30 kHz-1104 kHz', 'balanced' signal is connected to the 'Line Port'. The 'xDSL Port' is connected to a 'ZHP-r' device. The 'POTS' port is connected to a voltage source 'Vm' with a '600 ohms' load and a 'Hi Z' input. Inside the splitter, there is an 'LPF' (Low Pass Filter) on the line and 'SIG' (Signal) components on the xDSL lines. A label 'T1533080-99' is present. + +**Figure E.15/G.992.1 – Measurement of the remote splitter attenuation in the ADSL band** + +**E.2.4.2 Input impedance (loading of ADSL signal path)** + +The insertion loss caused by the low-pass filter in the band from 30 to 1104 kHz between nominal impedances with an input level of –10 dBm, as shown in Figures E.16 and E.17 shall be no more than 0.25 dB. + +![Figure E.16/G.992.1 – Measurement of loading effect of the CO splitter in the ADSL band. The diagram shows an 'External CO POTS splitter without HPF'. On the left, the 'PSTN' port is connected to a '900 ohms' load. The 'xDSL Port' is connected to a voltage source 'Vm' with a '100 ohms load'. The 'Line Port' is connected to a voltage source 'Z' with a 'Source 100 ohms', '30 kHz-1104 kHz', 'balanced' signal. Inside the splitter, there are two '0.12 µF' capacitors on the xDSL lines and an 'LPF' (Low Pass Filter) on the PSTN line. A label 'T1533090-99' is present.](d154006da381a924f5fd23a5d801f3cc_img.jpg) + +Figure E.16/G.992.1 – Measurement of loading effect of the CO splitter in the ADSL band. The diagram shows an 'External CO POTS splitter without HPF'. On the left, the 'PSTN' port is connected to a '900 ohms' load. The 'xDSL Port' is connected to a voltage source 'Vm' with a '100 ohms load'. The 'Line Port' is connected to a voltage source 'Z' with a 'Source 100 ohms', '30 kHz-1104 kHz', 'balanced' signal. Inside the splitter, there are two '0.12 µF' capacitors on the xDSL lines and an 'LPF' (Low Pass Filter) on the PSTN line. A label 'T1533090-99' is present. + +**Figure E.16/G.992.1 – Measurement of loading effect of the CO splitter in the ADSL band** + +![Figure E.17/G.992.1: Measurement of loading effect of the Remote Splitter in the ADSL band. The diagram shows a balanced source (100 ohms, 30 kHz-1104 kHz) connected to a 'Line port'. A '100 ohms load' is connected across the lines, with a voltage measurement 'Vm' taken across it. The 'Line port' is connected to an internal circuit containing an 'LPF' (Low Pass Filter) and a 'SIG' (Signal) block. The 'SIG' block is connected to a 'POTS' (Plain Old Telephone Service) output, which is terminated with a '600 ohms' load. The 'LPF' is also connected to an 'xDSL port'. A reference number 'T1533100-99' is present.](16e51d129488f259ccb14ae0db85061e_img.jpg) + +Figure E.17/G.992.1: Measurement of loading effect of the Remote Splitter in the ADSL band. The diagram shows a balanced source (100 ohms, 30 kHz-1104 kHz) connected to a 'Line port'. A '100 ohms load' is connected across the lines, with a voltage measurement 'Vm' taken across it. The 'Line port' is connected to an internal circuit containing an 'LPF' (Low Pass Filter) and a 'SIG' (Signal) block. The 'SIG' block is connected to a 'POTS' (Plain Old Telephone Service) output, which is terminated with a '600 ohms' load. The 'LPF' is also connected to an 'xDSL port'. A reference number 'T1533100-99' is present. + +**Figure E.17/G.992.1 – Measurement of loading effect of the Remote Splitter in the ADSL band** + +## E.2.5 Home premises physical considerations + +### E.2.5.1 Wiring considerations + +The running of ADSL signals and POTS signals together within a single multiple pair cable cross couples POTS noises into the received ADSL signals. These POTS noises are generated as the result of ringing, ringing trip, dial pulsing, and on/off hook operation. The levels of these noises are great enough that without adequate pair-to-pair isolation, errors in the received data are possible. This quality of service degradation may be mitigated by the use of interleaving or error control in any higher-level data communications protocol. + +The wiring configuration reference model, using separate cables, for an external POTS Splitter is shown in Figure E.18. If POTS and ADSL are to be run in the same cable, intercable isolation is assumed to be a minimum of 80 dB between pairs (i.e. CAT5 cable). It must be noted that the length of interpremises cabling must be included in the transmission link budgets. Use of other cable types (i.e. Quad or Standard twisted pairs) with lower separation specifications may result in higher errors and lower performance. + +![Figure E.18/G.992.1: Home Premise Wiring on Separate sheaths for ATU-R. The diagram shows a 'U-R' (User-Rate) interface on the left. A 'Remote splitter – (NID or external)' is connected to the 'Line port'. The splitter has an 'LPF' and 'SIG' block. The 'SIG' block is connected to a 'POTS' output, which is connected to a telephone. The 'LPF' is connected to an 'xDSL port', which is connected via a cable to an 'ATU-R' (ADSL Terminal Unit-Remote). A label 'Terminates with RJ14C on ATU-R' points to the connection. A reference number 'T1533120-99' is present.](d84a269046689e15f2dbd759c25cb5c7_img.jpg) + +Figure E.18/G.992.1: Home Premise Wiring on Separate sheaths for ATU-R. The diagram shows a 'U-R' (User-Rate) interface on the left. A 'Remote splitter – (NID or external)' is connected to the 'Line port'. The splitter has an 'LPF' and 'SIG' block. The 'SIG' block is connected to a 'POTS' output, which is connected to a telephone. The 'LPF' is connected to an 'xDSL port', which is connected via a cable to an 'ATU-R' (ADSL Terminal Unit-Remote). A label 'Terminates with RJ14C on ATU-R' points to the connection. A reference number 'T1533120-99' is present. + +**Figure E.18/G.992.1 – Home Premise Wiring on Separate sheaths for ATU-R** + +## E.3 Type 3 – ADSL above ISDN (ITU-T G.961 Appendix I or II) + +This subject is for further study. + +## E.4 Type 4 – Type for Japan + +### E.4.1 Introduction + +This subclause describes specifications and testing methods for a POTS splitter appropriate to Japan. Both a central office (CO) POTS splitter and a remote (R) POTS splitter shall conform to them. + +#### E.4.1.1 Frequencies and level of voiceband signal + +The frequencies and level of the voiceband signal provided by the local switch (LS) are as follows: + +- Signal frequency: 0.2-4.0 kHz. +- Signal level: maximum of +3 dBm. + +A signal of +36 dBm at 400 Hz may be used as a howler signal. + +#### E.4.1.2 External CO POTS Splitter Function + +The external CO POTS splitter may be located some distance from the ATU-C modem. To protect against DC faults, DC blocking capacitors should be included in the xDSL port of the POTS splitter. These capacitors configure parts of the input to the xDSL HPF function, so they must be included when the input impedance is calculated. If the POTS splitter function is included entirely within the modem, the capacitors should be included as part of the HPF function. + +#### E.4.1.3 ZHP Definition + +To facilitate testing of the POTS splitter independently of the actual modem or specific vendor, two ZHPs are defined to allow proper termination of the xDSL port during voiceband testing. The ZHPs are valid only for voiceband frequencies. They shall be as shown in Figure E.19. + +![Figure E.19/G.992.1 – ZHP definitions. The diagram shows two circuit models for ZHPs. The left model, labeled 'ZHP for External Central Office splitter (ZHP-c)', consists of two 0.10 µF capacitors in series with a parallel combination of a 100 Ω resistor and a 0.47 mH inductor. The right model, labeled 'ZHP Remote end (ZHP-r)', consists of two 0.10 µF capacitors in series with two 0.12 µF capacitors in series, followed by a parallel combination of a 100 Ω resistor and a 0.47 mH inductor. A small text 'T1533130-99' is present next to the ZHP-r label.](170d746d94ed03c3ae21a6a3b216ce6b_img.jpg) + +ZHP for External Central Office splitter (ZHP-c) + +ZHP Remote end (ZHP-r) T1533130-99 + +Figure E.19/G.992.1 – ZHP definitions. The diagram shows two circuit models for ZHPs. The left model, labeled 'ZHP for External Central Office splitter (ZHP-c)', consists of two 0.10 µF capacitors in series with a parallel combination of a 100 Ω resistor and a 0.47 mH inductor. The right model, labeled 'ZHP Remote end (ZHP-r)', consists of two 0.10 µF capacitors in series with two 0.12 µF capacitors in series, followed by a parallel combination of a 100 Ω resistor and a 0.47 mH inductor. A small text 'T1533130-99' is present next to the ZHP-r label. + +NOTE – Component Tolerances: Capacitors: 2.5%, Resistors: 1%, Coils: 5%. + +**Figure E.19/G.992.1 – ZHP definitions** + +### E.4.2 DC Characteristics + +This subclause contains the DC specifications, such as the loop DC current, the ringing, the L1-to-L2 DC voltage, the loop DC resistance, the isolation resistance, the L1-to-L2 capacitance, and the capacitance to ground, and the methods for measuring them. + +All requirements included in E.4.2 must be met in the presence of all POTS loop currents ranging from 0 to 130 mA. + +#### **E.4.2.1 Loop DC Current** + +The POTS splitter should ensure normal operation for loop DC currents ranging from 0 to 130 mA. + +#### **E.4.2.2 Ringing** + +The POTS splitter should accept the following ringing signals: + +- Ringing frequency: 15-30 Hz. +- Ringing AC: maximum 100 Vrms. +- Ringing DC (AC superimposed on DC): maximum minus 60 V. + +#### **E.4.2.3 L1-to-L2 DC Voltage** + +The POTS splitter should accept POTS L1-to-L2 DC voltages of 0 to minus 60 V. In addition, it should be able to withstand a POTS L1-to-L2 DC voltage of up to 120 V for at least 10 s. + +In addition, Recommendations K.20 and K.21 may be considered to ensure the POTS splitter availability when the surge voltage is applied to the POTS splitter. + +#### **E.4.2.4 DC Resistance** + +The L1-to-L2 DC resistance, at the PSTN interface with the U-C interface shorted, or at the POTS interface with the U-R interface shorted, shall be less than or equal to 40 Ω. + +#### **E.4.2.5 Isolation Resistance** + +The isolation resistance of the POTS splitter should remain intact under the following conditions. + +##### **E.4.2.5.1 L1-to-L2 Isolation Resistance** + +The L1-to-L2 isolation resistance at the PSTN interface with the U-C interface opened, or at the POTS interface with the U-R interface opened, shall be greater than or equal to 10 MΩ. + +##### **E.4.2.5.2 Isolation Resistance to Ground** + +The isolation resistance to ground at the PSTN interface with the U-C interface opened, or at the POTS interface with the U-R interface opened, shall be greater than or equal to 10 MΩ. + +#### **E.4.2.6 Capacitance** + +The capacitance of the POTS splitter should satisfy the following requirements. + +##### **E.4.2.6.1 L1-to-L2 Capacitance** + +The L1-to-L2 capacitance at the PSTN interface or the POTS interface shall be as follows: + +POTS splitter, either CO or Remote without the modem connected 250 nF Max (DC – 30 Hz) + +Modem input allowance, including the DC blocking capacitors at the CO end 35 nF Max (DC – 30 Hz) + +Modem with integral POTS splitter function or – external POTS splitter with both HPF and LPF functions, are the sum of the above 285 nF Max (DC – 30 Hz) + +##### **E.4.2.6.2 Capacitance to ground** + +The capacitance to ground at the PSTN interface with the U-C interface opened, or at the POTS interface with the U-R interface opened, shall be less than 1.0 nF. + +### E.4.3 AC Characteristics + +This subclause contains the AC specifications of the voiceband, such as the insertion loss, the attenuation variation, the delay distortion, the return loss, the longitudinal balance, the distortion caused by harmonics, and the termination, and the methods for measuring them. In addition, it contains specifications and measurement methods for the out band and the ADSL band. + +#### E.4.3.1 Voiceband + +This subclause describes the AC characteristics in the voiceband. + +##### E.4.3.1.1 Insertion Loss (at 1 kHz) + +The insertion loss of the POTS splitter should be less than or equal to $\pm 1.0$ dB. Using the test setup shown in Figures E.20 and E.21, the insertion loss from the source to termination shall be measured with and without the POTS splitter/ZHP combination inserted. + +![Diagram of transmission measurements in the voiceband for the CO POTS splitter.](4ee319aa8cb43ba512db6886578f9789_img.jpg) + +The diagram illustrates the test setup for measuring insertion loss in the voiceband for a CO POTS splitter. It shows a signal path from left to right: a termination block labeled 'ZTc (600 Ω)' connected to 'Test equipment'. This is followed by a vertical dashed line labeled 'PSTN'. The signal then enters a 'CO POTS splitter' block. Inside this block, the signal passes through an 'LPF' (Low Pass Filter) and a capacitor labeled '0.12 μF'. Below the splitter, a block labeled 'xDSL' connects to 'ZHP-c (load)'. After the splitter, the signal passes through another vertical dashed line labeled 'U-C', then a 'Test loop' block, and finally a third vertical dashed line labeled 'U-R'. The signal ends at a termination block labeled 'ZTr (600 Ω)'. A note on the left indicates 'ZTc is the normal termination in test set'. A reference code 'T1533140-99' is in the bottom right corner. + +Diagram of transmission measurements in the voiceband for the CO POTS splitter. + +ZPH-c = the impedance of the CO ADSL modem specified in Figure E.19 + +NOTE 1 – The DC blocking capacitors are only for the external POTS splitter without HPF function. When the POTS splitter includes the HPF function, the HPF function has capacitors for DC blocking. + +NOTE 2 – The test loop is specified in Figure E.22. + +**Figure E.20/G.992.1 – Transmission measurements in the voiceband for the CO POTS splitter** + +![Figure E.21/G.992.1 – Transmission measurements in the voiceband for the R POTS splitter. The diagram shows a test setup with three main sections separated by vertical dashed lines: U-C, U-R, and POTS. On the U-C side, a box labeled 'ZTc (600 ohms)' is connected to a 'Test loop' box. The 'Test loop' box is connected to the U-R section. In the U-R section, there is a 'Remote POTS splitter' box containing an 'LPF' (Low Pass Filter) box. Below the 'Remote POTS splitter' box, an 'xDSL' label points to a 'ZHP-r (load)' box. The 'Remote POTS splitter' box is connected to the POTS section. In the POTS section, there is a 'Test equipment' box connected to a 'ZTr (600 ohms)' box. A note above the 'ZTr (600 ohms)' box states 'ZTr is the normal termination in test set'. A small text 'T1533150-99' is at the bottom right of the diagram.](7188dd653353235466aea783783e26c8_img.jpg) + +``` + +graph LR + subgraph UC [U-C] + ZTc[ZTc +600 ohms] --| |--> TL[Test loop] + end + TL --| |--> UR + subgraph UR [U-R] + direction TB + subgraph RPS [Remote POTS splitter] + LPF[LPF] + end + ZHPr[ZHP-r +load] + RPS --- xDSL((xDSL)) + xDSL --- ZHPr + end + RPS --| |--> POTS_SEC + subgraph POTS_SEC [POTS] + TE[Test equipment] --> ZTr[ZTr +600 ohms] + end + +``` + +Figure E.21/G.992.1 – Transmission measurements in the voiceband for the R POTS splitter. The diagram shows a test setup with three main sections separated by vertical dashed lines: U-C, U-R, and POTS. On the U-C side, a box labeled 'ZTc (600 ohms)' is connected to a 'Test loop' box. The 'Test loop' box is connected to the U-R section. In the U-R section, there is a 'Remote POTS splitter' box containing an 'LPF' (Low Pass Filter) box. Below the 'Remote POTS splitter' box, an 'xDSL' label points to a 'ZHP-r (load)' box. The 'Remote POTS splitter' box is connected to the POTS section. In the POTS section, there is a 'Test equipment' box connected to a 'ZTr (600 ohms)' box. A note above the 'ZTr (600 ohms)' box states 'ZTr is the normal termination in test set'. A small text 'T1533150-99' is at the bottom right of the diagram. + +ZHP-r = the impedance of R ADSL modem specified in Figure E.19 + +NOTE – The test loop is specified in Figure E.22. + +**Figure E.21/G.992.1 – Transmission measurements in the voiceband for the R POTS splitter** + +![Figure E.22/G.992.1 – Test loop definition. The diagram shows a balanced circuit model with four resistors and one capacitor. Two horizontal lines represent the conductors. On the top line, there are two resistors labeled '140 ohms' in series. On the bottom line, there are also two resistors labeled '140 ohms' in series. A capacitor labeled '100 nF' is connected vertically between the midpoints of the top and bottom resistor pairs. A small text 'T1533160-99' is at the bottom right of the diagram.](82231328deb6eaae371ace98694254a7_img.jpg) + +``` + +\begin{circuitikz} +\draw (0,2) to[R, l=140 ohms, o-] (2,2) to[R, l=140 ohms, -o] (4,2); +\draw (0,0) to[R, l=140 ohms, o-] (2,0) to[R, l=140 ohms, -o] (4,0); +\draw (2,2) to[C, l=100 nF] (2,0); +\end{circuitikz} + +``` + +Figure E.22/G.992.1 – Test loop definition. The diagram shows a balanced circuit model with four resistors and one capacitor. Two horizontal lines represent the conductors. On the top line, there are two resistors labeled '140 ohms' in series. On the bottom line, there are also two resistors labeled '140 ohms' in series. A capacitor labeled '100 nF' is connected vertically between the midpoints of the top and bottom resistor pairs. A small text 'T1533160-99' is at the bottom right of the diagram. + +NOTE – This test loop model is valid only for voiceband frequencies. + +**Figure E.22/G.992.1 – Test loop definition** + +#### E.4.3.1.2 Attenuation distortion in voiceband variation + +The variation of insertion loss value from that measured with 1 kHz shall be measured using the test setup in Figures E.20 and E.21. The increase in attenuation distortion, relative to the 1 kHz insertion loss, caused by the POTS splitter with the ZHP (or modem) load attached using the test loop defined by Figure E.22, between 0.2 and 3.4 kHz should be less than $\pm 1.0$ dB and between 3.4 and 4.0 kHz should be less than $\pm 1.5$ dB. + +#### E.4.3.1.3 Delay Distortion + +The increase in the delay distortion cause by the POTS splitter shall be as follows: + +- 0.6-3.2 kHz: maximum of 200 $\mu\text{s}$ . +- 0.2-4.0 kHz: maximum of 250 $\mu\text{s}$ . + +The delay distortion of the POTS splitter shall be measured using Figures E.20 and E.21. + +#### E.4.3.1.4 Return Loss + +Figure E.23 defines the test configuration and the values of the test components that shall be used for impedance measurements in the voiceband for both the CO and R POTS splitter units. The return loss of each splitter under the specified conditions shall be as follows: + +- 11 dB (0.2-1.5 kHz). +- 10 dB (1.5-2.0 kHz). +- 9 dB (2.0-3.4 kHz). + +![Figure E.23/G.992.1 – Impedance measurements in the voiceband for the CO and R POTS splitters. The diagram shows a test configuration for impedance measurements. On the left, 'Test equipment' is connected to a 'ZNL-x' block labeled 'Return loss reference impedance'. A dashed vertical line labeled 'POTS/PSTN' separates this from the central 'POTS splitter' block. Inside the 'POTS splitter' block is an 'LPF' (Low Pass Filter). To the right of the LPF, a capacitor labeled '0.12 µF (used only at CO termination)' is connected in series with a 'ZHP-x' block labeled 'xDSL'. Another dashed vertical line labeled 'U-x' separates the splitter from the right side. On the far right, a 'ZNL-x' block is connected. The diagram is labeled 'T1533170-99' at the bottom right.](728a02fe4a04e7f91835147194997cd4_img.jpg) + +``` + +graph LR + TE[Test equipment] --- POTS_PSTN((POTS/PSTN)) + TE --- ZNL_ref[ZNL-x +Return loss reference +impedance] + POTS_PSTN --- PS[POTS splitter] + subgraph PS_Box [POTS splitter] + LPF[LPF] + Cap[0.12 µF +used only at CO +termination] + end + LPF --- Ux((U-x)) + LPF --- Cap + Cap --- ZHPx[ZHP-x +xDSL] + Ux --- ZNLx[ZNL-x] + +``` + +Figure E.23/G.992.1 – Impedance measurements in the voiceband for the CO and R POTS splitters. The diagram shows a test configuration for impedance measurements. On the left, 'Test equipment' is connected to a 'ZNL-x' block labeled 'Return loss reference impedance'. A dashed vertical line labeled 'POTS/PSTN' separates this from the central 'POTS splitter' block. Inside the 'POTS splitter' block is an 'LPF' (Low Pass Filter). To the right of the LPF, a capacitor labeled '0.12 µF (used only at CO termination)' is connected in series with a 'ZHP-x' block labeled 'xDSL'. Another dashed vertical line labeled 'U-x' separates the splitter from the right side. On the far right, a 'ZNL-x' block is connected. The diagram is labeled 'T1533170-99' at the bottom right. + +$ZNL-c = 150 \Omega + (830 \Omega \parallel 72 \text{ nF})$ + +$ZNL-r = 150 \Omega + (72 \text{ nF} \parallel (830 \Omega + 1 \mu\text{F}))$ + +ZHP-c = the impedance presented to the POTS connection by an ATU-C through the capacitance of the POTS splitter DC blocking capacitors + +ZHP-r = the impedance presented to the POTS connection by an ATU-R + +NOTE – The DC blocking capacitors are only for the external CO POTS splitter without the HPF function. The ZNL-c and ZNL-r are valid only for voiceband frequencies. + +**Figure E.23/G.992.1 – Impedance measurements in the voiceband for the CO and R POTS splitters** + +#### E.4.3.1.5 Distortion caused by harmonics + +The distortion contributed by the low-pass filter shall be measured using the test configurations in Figures E.20 and E.21, and the null loop. + +With an applied tone set as per the latest North American measurement practices, then, at a level of $-9 \text{ dBm}$ , the second and third order intermodulation distortion products shall be at least 57 dB and 60 dB, respectively, below the received signal level. + +#### E.4.3.1.6 Longitudinal balance + +The longitudinal balance of the POTS splitter shall be greater than 58 dB for frequencies ranging from 0.2 to 3.4 kHz and a DC bias current of 50 mA will be applied. + +See Figures E.24 and E.25. + +![Figure E.24/G.992.1 – Longitudinal balance CO test setup. This schematic diagram shows a central rectangular block representing a device under test. On its left side, there is an 'xDSL port' at the top, which is 'Shorted' (connected between its two terminals), and a 'PSTN' port below it. On its right side, there is a 'Line port'. An 'LPF' (Low Pass Filter) block is connected to the 'PSTN' port. An 'LB test source' is connected to the 'LPF' block. Two capacitors, each labeled '0.12 μF', are connected between the 'xDSL port' and the 'Line port'. An 'LB test load' is connected to the 'Line port'. The identifier 'T1533180-99' is located at the bottom right of the diagram.](444aae06b7856be544a8e1bbae1302c3_img.jpg) + +Figure E.24/G.992.1 – Longitudinal balance CO test setup. This schematic diagram shows a central rectangular block representing a device under test. On its left side, there is an 'xDSL port' at the top, which is 'Shorted' (connected between its two terminals), and a 'PSTN' port below it. On its right side, there is a 'Line port'. An 'LPF' (Low Pass Filter) block is connected to the 'PSTN' port. An 'LB test source' is connected to the 'LPF' block. Two capacitors, each labeled '0.12 μF', are connected between the 'xDSL port' and the 'Line port'. An 'LB test load' is connected to the 'Line port'. The identifier 'T1533180-99' is located at the bottom right of the diagram. + +**Figure E.24/G.992.1 – Longitudinal balance CO test setup** + +![Figure E.25/G.992.1 – Longitudinal balance remote test setup. This schematic diagram shows a central rectangular block representing a device under test. On its left side, there is a 'Line port'. An 'LB test load' is connected to this 'Line port'. On its right side, there is an 'xDSL port' at the top and a 'POTS' port below it. An 'LPF' (Low Pass Filter) block is connected to the 'POTS' port. An 'LB test source' is connected to the 'LPF' block. Two capacitors, each labeled '0.12 μF', are connected between the 'xDSL port' and the 'Line port'. The identifier 'T1533180-99' is located at the bottom right of the diagram.](f7a1b96924f2d36f5643700fbb7cc2ea_img.jpg) + +Figure E.25/G.992.1 – Longitudinal balance remote test setup. This schematic diagram shows a central rectangular block representing a device under test. On its left side, there is a 'Line port'. An 'LB test load' is connected to this 'Line port'. On its right side, there is an 'xDSL port' at the top and a 'POTS' port below it. An 'LPF' (Low Pass Filter) block is connected to the 'POTS' port. An 'LB test source' is connected to the 'LPF' block. Two capacitors, each labeled '0.12 μF', are connected between the 'xDSL port' and the 'Line port'. The identifier 'T1533180-99' is located at the bottom right of the diagram. + +**Figure E.25/G.992.1 – Longitudinal balance remote test setup** + +#### **E.4.3.2 Out Band** + +The band between the voiceband and ADSL band is defined as the out band in E.4. In Japan, the out band is used with pulse metering (16 kHz), OVS signals (7.8 kHz), and OFFTALK services (0-7.0 kHz). These specifications and measurement methods of the Out Band require further study. + +#### **E.4.3.3 ADSL Band** + +This subclause describes the AC characteristics in the ADSL band. + +##### **E.4.3.3.1 ADSL Band Attenuation** + +The attenuation in the stop band of the low-pass filter (i.e. the difference in attenuation measured with and without the low-pass filter), shown in Figures E.26 and E.27, shall be greater than 65 dB for frequencies ranging from 25 kHz to 300 kHz and 55 dB for frequencies ranging from 300 kHz to 1104 kHz with an input level of 10 dBm. + +![Figure E.26/G.992.1 – Measurement of the CO POTS splitter attenuation in the ADSL band. The diagram shows an 'External CO POTS splitter without HPF'. On the left, an 'xDSL port' is connected to a 'ZHP-c' unit. The 'PSTN' port is connected to a '600 Ω' resistor and a voltage source 'Vm', with a 'Hi Z' input. The 'Line port' is connected to a voltage source labeled 'Source: 100 Ω 25-1104 kHz balanced'. Inside the splitter, there is an 'LPF' (Low Pass Filter) and two '0.12 μF' capacitors. The diagram is labeled 'T1533200-99'.](79e6576a312f8ddac8c706d78fae4bcf_img.jpg) + +Figure E.26/G.992.1 – Measurement of the CO POTS splitter attenuation in the ADSL band. The diagram shows an 'External CO POTS splitter without HPF'. On the left, an 'xDSL port' is connected to a 'ZHP-c' unit. The 'PSTN' port is connected to a '600 Ω' resistor and a voltage source 'Vm', with a 'Hi Z' input. The 'Line port' is connected to a voltage source labeled 'Source: 100 Ω 25-1104 kHz balanced'. Inside the splitter, there is an 'LPF' (Low Pass Filter) and two '0.12 μF' capacitors. The diagram is labeled 'T1533200-99'. + +**Figure E.26/G.992.1 – Measurement of the CO POTS splitter attenuation in the ADSL band** + +![Figure E.27/G.992.1 – Measurement of the R POTS splitter attenuation in the ADSL band. The diagram shows a 'Remote POTS splitter'. On the left, a voltage source labeled 'Source: 100 ohms 25-1104 kHz balanced' is connected to the 'Line port'. Inside the splitter, there is an 'LPF'. The 'xDSL port' is connected to a 'ZHP-r' unit. The 'POTS' port is connected to a '600 ohms' resistor and a voltage source 'Vm', with a 'Hi Z' input. The diagram is labeled 'T1533210-99'.](8e98e177eaadc4544881ac194a6684f9_img.jpg) + +Figure E.27/G.992.1 – Measurement of the R POTS splitter attenuation in the ADSL band. The diagram shows a 'Remote POTS splitter'. On the left, a voltage source labeled 'Source: 100 ohms 25-1104 kHz balanced' is connected to the 'Line port'. Inside the splitter, there is an 'LPF'. The 'xDSL port' is connected to a 'ZHP-r' unit. The 'POTS' port is connected to a '600 ohms' resistor and a voltage source 'Vm', with a 'Hi Z' input. The diagram is labeled 'T1533210-99'. + +**Figure E.27/G.992.1 – Measurement of the R POTS splitter attenuation in the ADSL band** + +### E.4.3.3.2 Input Impedance + +The insertion loss caused by the low-pass filter in the band from 25 kHz to 1104 kHz between nominal impedances with an input level of –10 dBm, as shown in Figures E.28 and E.29, shall be less than 0.35 dB. + +![Figure E.28/G.992.1 – Measurement of loading effect of the CO POTS splitter in the ADSL band. The diagram shows the 'xDSL port' connected to a '600 Ω' resistor and a voltage source 'Vm'. The 'PSTN' port is connected to an 'LPF'. The 'Line port' is connected to a voltage source labeled 'Source: 100 Ω 25-1104 kHz balanced'. Inside the splitter, there are two '0.12 μF' capacitors. A '100 Ω load' is connected to the 'xDSL port'. The diagram is labeled 'T1533220-99'.](2f903f194dbf70f3aa6c281a6f96db03_img.jpg) + +Figure E.28/G.992.1 – Measurement of loading effect of the CO POTS splitter in the ADSL band. The diagram shows the 'xDSL port' connected to a '600 Ω' resistor and a voltage source 'Vm'. The 'PSTN' port is connected to an 'LPF'. The 'Line port' is connected to a voltage source labeled 'Source: 100 Ω 25-1104 kHz balanced'. Inside the splitter, there are two '0.12 μF' capacitors. A '100 Ω load' is connected to the 'xDSL port'. The diagram is labeled 'T1533220-99'. + +**Figure E.28/G.992.1 – Measurement of loading effect of the CO POTS splitter in the ADSL band** + +![Circuit diagram for measuring the loading effect of the R POTS splitter in the ADSL band. A balanced source (100 ohms, 25-1104 kHz) is connected to the 'Line port' of a device. A 100-ohm load and a voltmeter (Vm) are connected across the line. The device contains an 'LPF' (Low Pass Filter) and a 'POTS' (Plain Old Telephone Service) splitter. The 'xDSL port' is connected to the LPF output. The POTS output is connected to a 600 ohm load. The diagram is labeled 'T1533230-99'.](1b54a9e1b22fff830f6767035580c39e_img.jpg) + +Circuit diagram for measuring the loading effect of the R POTS splitter in the ADSL band. A balanced source (100 ohms, 25-1104 kHz) is connected to the 'Line port' of a device. A 100-ohm load and a voltmeter (Vm) are connected across the line. The device contains an 'LPF' (Low Pass Filter) and a 'POTS' (Plain Old Telephone Service) splitter. The 'xDSL port' is connected to the LPF output. The POTS output is connected to a 600 ohm load. The diagram is labeled 'T1533230-99'. + +**Figure E.29/G.992.1 – Measurement of loading effect of the R POTS splitter in the ADSL band** + +## ANNEX F + +### ATU-x Classification and Performance for Region A (North America) + +#### F.1 Classification definitions + +The ATU-x capability requirements for category I (basic) and category II (optional) shall be as specified in Table F.1. All types of equipment shall interwork with at least category I performance and shall support the characteristics of a category I ATU as defined in Table F.1. All category II equipment shall interwork with category II performance and shall support the characteristics of a category II ATU as defined in Table F.1. + +**Table F.1/G.992.1 – ATU-x classification by category** + +| Characteristics | Category I (basic) | Category II (optional) | +|-----------------|--------------------------|------------------------| +| Trellis option | Off | On | +| Spectrum | Non-overlapping spectrum | Overlapping spectrum | + +#### F.2 Performance requirements + +ADSL transmission is assessed in terms of performance against an objective of coverage over test loops (see Recommendation G.996.1) and in the presence of defined noise models (see Recommendation G.996.1). + +The ADSL control channel and other duplex channels are evaluated with all test loops. + +The specific combinations of loops (see Recommendation G.996.1) and rates shown in Table F.2 shall be tested for either category I or category II ATUs, as indicated. + +**Table F.2/G.992.1 – Loop sets and maximum rates for category I and II testing** + +| Loop sets | ATU Category | Net data rate (kbit/s) | | | | +|-------------------------|--------------|------------------------|--------------|------------------|----------------| +| | | STM only | | ATM and STM | | +| | | Simplex (AS0) | Duplex (LS0) | Downstream (AS0) | Upstream (LS0) | +| T #7, T #13 | I | 1536 | 16 | 1696 | 160 | +| | | 1536 | 160 | | | +| C #4, C #6, C #7, Mid-C | I | 5920 | 224 | 6144 | 224 | +| T #7, T #9, T #13 | II | 1536 | 16 | 1696 | 160 | +| | | 1536 | 160 | | | +| C #4, C #6, C #8, Mid-C | II | 5504 | 640 | 6144 | 640 | + +NOTE – The channelization shall be tested with full overhead framing as defined in 7.4.1.2 and 8.4.1.2. + +### F.2.1 Crosstalk interference + +Tables F.3 and F.4 show the combinations of test loops and numbers of interferers to be tested for category I ATU's, downstream and upstream respectively. Tables F.5 and F.6 show the combinations of test loops and numbers of interferers to be tested for category II ATU's, downstream and upstream respectively. Net data rates to be tested and the allocation to bearer channels shall be as defined in Table F.2. + +For the crosstalk interference test, the S and D parameters shall be configured such that the single payload transfer delay of $4 + (S - 1)/4 + SD/4$ ms is less than 12 ms. + +**Table F.3/G.992.1 – Crosstalk tests for category I (downstream)** + +| Test loops (see G.996.1) | Margin (dB) | Crosstalk (see G.996.1) (Note) | | | | +|--------------------------|-------------|---------------------------------------------|-----------|----------|---------------------| +| | | ADSL upstream NEXT and ADSL downstream FEXT | HDSL NEXT | DSL NEXT | T1 NEXT adj. binder | +| T #7, T #13 | 6 | – | – | 24 | – | +| C #4 | 6 | 24 | – | 24 | – | +| C #6 | 6 | – | 20 | – | – | +| C #7 | 6 | 10 | – | 10 | – | +| Mid-C | 3 | – | – | – | 10 | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of $-140$ dBm/Hz to form a composite power spectral density. + +**Table F.4/G.992.1 – Crosstalk tests for category I (upstream)** + +| Test loops
(see G.996.1) | Margin
(dB) | Crosstalk (see G.996.1) (Note) | | | | +|-----------------------------|----------------|---------------------------------------------------|--------------|-------------|------------------------| +| | | ADSL downstream
NEXT and ADSL
upstream FEXT | HDSL
NEXT | DSL
NEXT | T1 NEXT
adj. binder | +| T #7, T #13 | 6 | – | – | 24 | – | +| C #4 | 6 | 24 | – | 24 | – | +| C #6 | 6 | – | 20 | – | – | +| C #7 | 6 | 10 | – | 10 | – | +| Mid-C | 3 | – | – | – | 10 | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of –140 dBm/Hz to form a composite power spectral density. + +**Table F.5/G.992.1 – Crosstalk tests for category II (downstream)** + +| Test loops
(see G.996.1) | Margin
(dB) | Crosstalk (see G.996.1) (Note) | | | | +|-----------------------------|----------------|---------------------------------------------------|--------------|-------------|--------------------------------| +| | | ADSL upstream
NEXT and ADSL
downstream FEXT | HDSL
NEXT | DSL
NEXT | T1 NEXT
from adj.
binder | +| T #7, T #9, T #13 | 6 | – | – | 24 | – | +| C #4, C #6, C #8 | 6 | 10 | 10 | 24 | – | +| Mid-C | 6 | – | – | 10 | 24 | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of –140 dBm/Hz to form a composite power spectral density. + +**Table F.6/G.992.1 – Crosstalk tests for category II (upstream)** + +| Test loops | Margin
(dB) | Crosstalk (Note) | | | | +|-------------------|----------------|------------------------------------------------------|--------------|-------------|--------------------------------| +| | | ADSL
downstream
NEXT and ADSL
upstream FEXT | HDSL
NEXT | DSL
NEXT | T1 NEXT
from adj.
binder | +| T #7, T #9, T #13 | 6 | – | – | 24 | – | +| C #4, C #6, C #8 | 6 | 10 | 10 | 24 | – | +| Mid-C | 6 | – | – | 10 | 24 | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of –140 dBm/Hz to form a composite power spectral density. + +### F.2.2 Impulse noise + +Tables F.7 and F.8 show the combinations of test loops, interferers, and data rates to be tested. Net data rates to be tested and the allocation to bearer channels shall be as defined in Table F.2. The type of crosstalk interference applicable for each test is taken from the corresponding test in Tables F.3, F.4, F.5, or F.6. The total power of the applied interference is fixed at 4 dB below the reference level. + +**Table F.7/G.992.1 – Test loops, interferers, and data rates for impulse tests for category I** + +| Test Loops (see G.996.1) | Interferers (see G.996.1) | | | +|--------------------------|---------------------------|-----------|----------------------| +| | Impulse 1 | Impulse 2 | crosstalk (see Note) | +| T #7, T #13 | Yes | yes | yes | +| C #4, C #6, C #7 | Yes | yes | yes | +| Mid-C 1829 m (6 kft) | Yes | yes | yes | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of –140 dBm/Hz to form a composite power spectral density. + +**Table F.8/G.992.1 – Test loops, interferers, and data rates for impulse tests for category II** + +| Test Loops (see G.996.1) | Interferers (see G.996.1) | | | +|--------------------------|---------------------------|-----------|----------------------| +| | Impulse 1 | Impulse 2 | crosstalk (see Note) | +| T #7, T #9, T #13 | yes | yes | yes | +| C #4, C #6, C #8 | yes | yes | yes | +| Mid-C 1829 m (6 kft) | yes | yes | yes | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of –140 dBm/Hz to form a composite power spectral density. + +### F.2.3 POTS + +Tables F.9 and F.10 show the combinations of test loops, interferers, and data rates to be tested for categories I and II. The type of crosstalk interference applicable for each test is taken from the corresponding test in Tables F.3, F.4, F.5, or F.6. The total power of the applied interference is fixed at 4 dB below the reference or 0 dB margin level. + +Bit error requirements related to the POTS interference test are for further study. + +**Table F.9/G.992.1 – Test loops, interferers, and data rates for POTS tests category I** + +| Test loop (see G.996.1) | Interferers (see G.996.1) | | +|-------------------------|---------------------------|----------------------| +| | POTS signalling | Crosstalk (see Note) | +| ANSI (7, 13) | yes | yes | +| CSA (4, 6, 7) | yes | yes | +| Mid-CSA loop | yes | yes | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of –140 dBm/Hz to form a composite power spectral density. + +**Table F.10/G.992.1 – Test loops, interferers, and data rates +for POTS tests category II** + +| Test loop (see G.996.1) | Interferers (see G.996.1) | | +|-------------------------|---------------------------|----------------------| +| | POTS signalling | Crosstalk (see Note) | +| ANSI (7, 9, 13) | yes | yes | +| CSA (4, 6, 8) | yes | yes | +| CSA (6) | yes | yes | +| Mid-CSA loop | yes | yes | + +NOTE – The indicated interferers for each test are summed together with AWGN with PSD of $-140 \text{ dBm/Hz}$ to form a composite power spectral density. + +## ANNEX G + +### **ATU-x Classification and Performance for Region B (Europe)** + +#### **G.1 Performance requirements** + +ADSL transmission is assessed in terms of performance against an objective of coverage over test loops (see Recommendation G.996.1) and in the presence of defined noise models (see Recommendation G.996.1). + +The following conditions apply: + +- $\text{BER} < 10^{-7}$ with 6 dB margin. +- Annex A (operation over POTS with a splitter). +- Interleaved mode of operation is allowed. +- Trellis option is not enabled. + +Table G.1 applies where both ATU-C and ATU-R are of a non-overlapped spectrum type using PSD Mask for reduced NEXT defined in A.1.3. + +Table G.2 applies where both ATU-C and ATU-R are of an overlapped spectrum type using PSD Mask defined in A.1.2. + +Table G.1 applies where one ATU-x is a non-overlapped spectrum type and one ATU-x is an overlapped spectrum type. In this case the overlapped spectrum ATU-x does not need to comply with the PSD Mask for reduced NEXT defined in A.1.3. + +For the crosstalk interference test, the S and D parameters shall be configured such that the single payload transfer delay of $4 + (S - 1)/4 + SD/4 \text{ ms}$ is less than 12 ms. + +**Table G.1/G.992.1 – Test Loops & Performance Requirements** + +| Loop
(see G.996.1) | Loop Insertion
Loss @
300 kHz | Nominal
length
"X"
(km) | Down Net
Data Rate
(kbit/s) | Up Net
Data Rate
(kbit/s) | Noise @
ATU-C | Noise @
ATU-R | +|-------------------------------|----------------------------------------------|--------------------------------------------|--------------------------------------------|------------------------------------------|--------------------------|--------------------------| +| ETSI-0 | 0 dB | 0 | 6144 | 640 | None | None | +| ETSI-1 | 40 dB | 2.80 | 4096 | 320 | Euro-K | ETSI-A | +| ETSI-1 | 50 dB | 3.50 | 2048 | 128 | Euro-K | ETSI-A | +| ETSI-1 | 20 dB | 1.40 | 6144 | 640 | ETSI-B | ETSI-B | +| ETSI-1 | 30 dB | 2.15 | 2048 | 512 | ETSI-B | ETSI-B | +| ETSI-1 | 60 dB | 4.20 | 576 | 128 | ETSI-A | ETSI-A | +| ETSI-1 | 60 dB | 4.20 | 1536 | 512 | AWGN -140 | AWGN -140 | + +**Table G.2/G.992.1 – Test Loops & Performance Requirements** + +| Loop
(see G.996.1) | Loop Insertion
Loss @ 300
kHz | Nominal
length
"X" (km) | Down Net
Data Rate
(kbit/s) | Up Net
Data Rate
(kbit/s) | Noise @
ATU-C | Noise @
ATU-R | +|-------------------------------|----------------------------------------------|----------------------------------------|--------------------------------------------|------------------------------------------|--------------------------|--------------------------| +| ETSI-0 | 0 dB | 0 | 6144 | 640 | None | None | +| ETSI-1 | 40 dB | 2.80 | 4096 | 320 | Euro-K | ETSI-A | +| ETSI-1 | 50 dB | 3.50 | 2048 | 128 | Euro-K | ETSI-A | +| ETSI-1 | 20 dB | 1.40 | 6144 | 640 | ETSI-B | ETSI-B | +| ETSI-1 | 30 dB | 2.15 | 2048 | 512 | ETSI-B | ETSI-B | +| ETSI-1 | 60 dB | 4.20 | 576 | 128 | ETSI-A | ETSI-A | +| ETSI-1 | 60 dB | 4.20 | 1536 | 512 | AWGN -140 | AWGN -140 | + +**APPENDIX I****ATM Layer to Physical Layer Logical Interface** + +This appendix describes the logical interface between the ATM Layer and the Physical Layer. The Physical Layer (i.e. the ATU) consists of the Cell Specific Transmission Convergence Sublayer (Cell TC), the Mux/Sync Control block (ADSL framing) and the other physical layer functions (FEC and modulation), as shown in Figures 5-2 and 5-4. + +The ATM layer to Physical Layer interface (named V-C at the ATU-C and named T-R at the ATU-R) are shown in Figure I.1. TxRef\* is optional at ATU-C, RxRef\* is optional at ATU-R. + +![Diagram of the ATM to physical layer logical interface at ATU-C and ATU-R. The diagram shows the ATM layer on the left and the Physical layer on the right, connected by a UTOPIA2 interface. The ATM layer contains two ports, ATM0 and ATM1, each with a PORT block. The Physical layer contains two Cell TC blocks, one for each port, which are connected to a common MUX-SYNC CONTROLLER. The MUX-SYNC CONTROLLER is connected to two CRC blocks. The UTOPIA2 interface between the ATM layer and the Physical layer includes signals: RxClk, RxClav[0], RxEnb*, RxSOC, RxData[7..0], RxAddr[4..0], TxClk, TxClav[0], TxEnb*, TxSOC, TxData[7..0], TxAddr[4..0], TxRef*, and RxRef*. A reference point A is indicated at the bottom right of the Physical layer.](670a9057bbab8c7c0eb91db3a6de4d55_img.jpg) + +ATM to PHY Layer Interface +(V-C and T-R interface) + +T1533240-99 + +Diagram of the ATM to physical layer logical interface at ATU-C and ATU-R. The diagram shows the ATM layer on the left and the Physical layer on the right, connected by a UTOPIA2 interface. The ATM layer contains two ports, ATM0 and ATM1, each with a PORT block. The Physical layer contains two Cell TC blocks, one for each port, which are connected to a common MUX-SYNC CONTROLLER. The MUX-SYNC CONTROLLER is connected to two CRC blocks. The UTOPIA2 interface between the ATM layer and the Physical layer includes signals: RxClk, RxClav[0], RxEnb\*, RxSOC, RxData[7..0], RxAddr[4..0], TxClk, TxClav[0], TxEnb\*, TxSOC, TxData[7..0], TxAddr[4..0], TxRef\*, and RxRef\*. A reference point A is indicated at the bottom right of the Physical layer. + +**Figure I.1/G.992.1 – ATM to physical layer logical interface at ATU-C and ATU-R** + +The ATM Layer performs cell multiplexing from and demultiplexing to the appropriate physical port (i.e. latency path – fast or interleaved) based on the Virtual Path Identifier (VPI) and Virtual Connection Identifier (VCI), both contained in the ATM cell header. Configuration of the cell demultiplexing process is done by ATM Layer management. + +A Cell Specific Transmission Convergence sublayer (Cell TC) is provided for each latency path separately. Cell TC functionalities are specified in 7.2.3. + +The logical input and output interfaces at the V-C reference point for ATM transport is based on the UTOPIA Level 2 interface with cell level handshake. The logical interface is given in Tables I.1 and I.2 and shown in Figure I.1. When a flow control flag is activated by the ATU-C (i.e. the ATU-C wants to transmit or receive a cell), the ATM layer initiates a cell Tx or cell Rx cycle (53 byte transfer). The ATU-x should support transfer of a complete cell within 53 consecutive clock cycles. The UTOPIA Tx and Rx clocks are mastered from the ATM layer. The same logical input and output interfaces based on the UTOPIA Level 2 interface can be used at the T-R reference point in the ATU-R. + +**Table I.1/G.992.1 – UTOPIA Level 2 ATM Interface Signals for Tx** + +| Signal Name | Direction | Description | +|----------------------------------|------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmit Interface | | | +| TxClk | ATM to PHY | Timing signal for transfer | +| TxClav[0] | PHY to ATM | Asserted to indicate that the PHY Layer has buffer space available to receive a cell from the ATM Layer (de-asserted 4 cycles before the end of the cell transfer) | +| TxEnb* | ATM to PHY | Asserted to indicate that the PHY Layer must sample and accept data during the current clock cycle | +| TxSOC | ATM to PHY | Identifies the cell boundary on TxData | +| TxData[7..0] | ATM to PHY | ATM Cell Data transfer (8-bit mode) | +| TxAddr[4..0] | ATM to PHY | PHY device address to select the device that will be active or polled for TxClav status | +| TxRef* | ATM to PHY | Network Timing Reference (8 kHz timing signal) (only at V-C interface) | + +**Table I.2/G.992.1 – UTOPIA Level 2 ATM Interface Signals for Rx** + +| Signal Name | Direction | Description | +|---------------------------------|------------|-------------------------------------------------------------------------------------------------------------------------------------------------------| +| Receive Interface | | | +| RxClk | ATM to PHY | Timing signal for transfer | +| RxClav[0] | PHY to ATM | Asserted to indicate to the ATM Layer that the PHY Layer has a cell ready for transfer to the ATM Layer (de-asserted at the end of the cell transfer) | +| RxEnb* | ATM to PHY | Asserted to indicate that the ATM Layer will sample and accept data during the next clock cycle | +| RxSOC | PHY to ATM | Identifies the cell boundary on RxData | +| RxData[7..0] | PHY to ATM | ATM Cell Data transfer (8-bit mode) | +| RxAddr[4..0] | ATM to PHY | PHY device address to select the device that will be active or polled for RxClav status | +| RxRef* | PHY to ATM | Network Timing Reference (8 kHz timing signal) (only at T-R interface) | + +More details on the UTOPIA Level 2 interface can be found in the ATM Forum Specification, af.phy-0039.000, published in June 1995. + +## APPENDIX II + +### Dynamic (on-line) Rate Adaptation + +#### II.1 Introduction + +The Rate Adaptation at Start-up procedure (see 10.8 and 10.9) optimizes the modem settings for the existing channel conditions and service requirements. Channel conditions and service requirements may, however, change over time. In order to avoid a lengthy restart to reconfigure the modem, a mechanism that allows reconfiguration of the modem during Showtime is proposed. This mechanism is referred to as Dynamic Rate Adaptation (DRA). + +This appendix describes an AOC-based DRA mechanism. The purpose of this DRA mechanism is + +not to provide "on-the-fly" Rate Adaptation, where the modem configuration would change continuously, tracking the slightest variation of the line conditions without affecting the user-traffic, but rather to allow for occasional changes, which would involve service interruption of the order of tens of milliseconds. + +This DRA procedure should be augmented by a non-AOC-based fast Warm Restart procedure for the case where the AOC channel becomes unreliable. The specification of this Warm Restart procedure however is for further study. + +### II.1.1 General concepts + +The proposed DRA mechanism is a mechanism that during ShowTime, without the need to restart: + +- Allows rate modifications (up and downgrades) for both US and DS. +NOTE – Rate modification implies more than just bit-rate but also FEC and Interleaving settings. +- Allows rate repartitionings between the fast and the interleaved paths. +- Provides an AOC-based protocol that prior to the actual swap of the modem configuration runs without interfering with the user-traffic. +- Allows the ATU-C to gather information or metrics about operational conditions. +- Follows the same philosophy as RA during Start-up. + +It should be noted, however, that the DRA mechanism does not: + +- Provide an on-the-fly rate adaptation solution, where the modem configuration would track the slightest variation of the line conditions without affecting the user-traffic. +- Specify the policy that describes – based on the gathered metrics and/or additional information – when or how to reconfigure the modem settings. Furthermore, the DRA mechanism assumes that the policy resides within the network and not within customer equipment. +- Require the actual reconfiguration to occur error-free. During the transition period, user-data may be lost during tens of milliseconds for both communication directions. + +## II.2 DRA protocol and messages + +### II.2.1 DRA concept + +The DRA protocol expands the AOC message set by defining new DRA-AOC messages. The purpose of these new messages is to: + +- 1) allow the ATU-C to gather detailed information about the line conditions (*monitoring*); +- 2) propose to the ATU-R a new rate configuration – if needed – (*configuration*); +- 3) exchange configuration information – if the proposal is accepted by ATU-R (*exchange*); +- 4) initiate and synchronize a swap to the new rate configuration (*swap*). + +The next paragraphs highlight how each of these functions is implemented through AOC messages. + +The maximum length of the new AOC-messages is limited to 13 bytes, this being the maximum length of an AOC message. + +Just like AOC-messages, DRA-AOC messages shall be transmitted 5 times for protection against transmission errors. For concatenated messages composed of multiple 13-byte messages, each 13-byte message shall be sent 5 times consecutively, before the next 13-byte message is sent 5 times consecutively. + +### II.2.2 DRA-AOC messages + +Table II.1 lists the new DRA-AOC command set. + +**Table II.1/G.992.1 – DRA Command Set** + +| Header | Command | Length (bytes) | Message | Source | +|------------------|---------------------------------------|----------------|---------------------------|-------------| +| DF 16 | 00 16 | 7 | DRA_Monitor_Request | ATU-C | +| DF 16 | 20 16 | 13 | DRA_Monitor_Reply | ATU-R | +| DF 16 | 40 16 ... 42 16 | 3 × 13 | DRA_Configuration_Request | ATU-C | +| DF 16 | 60 16 | 4 | DRA_Configuration_Reply | ATU-R | +| DF 16 | 80 16 ... 9F 16 | 4 × 13 | DRA_Exchange_Request | ATU-C/ATU-R | +| DF 16 | A0 16 | 4 | DRA_Exchange_Reply | ATU-R/ATU-C | +| DF 16 | C0 16 | 8 | DRA_Swap_Request | ATU-C | +| DF 16 | E0 16 | 8 | DRA_Swap_Reply | ATU-R | +| DF 16 | Other | | Reserved | | + +NOTE – Reserved bits or fields shall be encoded as 0. + +### II.3 Monitoring + +The ATU-C monitors the changing line conditions. Through the EOC, the SNR margin and the line attenuation from the DS can be retrieved. However, more information may be required in order to decide whether or not a new configuration should be proposed, and if so what the new proposal should be. In order to allow the ATU-C to gather more information about the DS, two new AOC messages are defined. + +NOTE – The ATU-C already monitors the US thus no US-related information needs to be exchanged. + +#### II.3.1 DRA\_Monitor\_Request + +DRA\_Monitor\_Request is generated by the ATU-C; its format is given in Table II.2. + +**Table II.2/G.992.1 – DRA Monitor Request** + +| Message Format | Bits | Definition | +|-----------------------|------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Monitor_Request { | | | +| Header | 8 | DF 16 | +| Command | 8 | 00 16 | +| Reserved | 3 | | +| Req_SNR_Margin | 5 | Required SNR Margin to be used for the Bmax that will be calculated by the ATU-R and returned within DRA_Monitor_Reply message. Unsigned value in dB. Allowed values ranging from 0 to 15 dB. | +| Reserved | 32 | | +| } | | | + +#### II.3.2 DRA\_Monitor\_Reply + +The ATU-R may also send this message unsolicited, whenever considered necessary: e.g. when line conditions change significantly and endanger proper operation of the modem and in particular the AOC channel. However, in order to avoid these messages to monopolize the AOC channel, after sending an unsolicited DRA\_Monitor\_Reply, the ATU-R shall not send another one before having + +received a DRA\_Monitor\_Request from the ATU-C. + +The format of this DRA-AOC message is shown in Table II.3. + +**Table II.3/G.992.1 – DRA-AOC message format** + +| Message Format | Bits | Definition | +|-----------------------|------|-------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Monitor_Reply { | | | +| Header | 8 | DF 16 | +| Command | 8 | 20 16 | +| Attenuation | 6 | See R-MSG-RA ( current value ) | +| Req_SNR_Margin | 5 | Requested SNR margin [ used in Bmax calculation, see below ]. Same format as Req_SNR_Margin in DRA_Monitor_Request . | +| Noise_Margin | 5 | See R-MSG-RA ( current value ) | +| Coding_Gain | 4 | See R-MSG-RA ( used in Bmax calculation ) | +| Bmax | 12 | See R-MSG-RA ( see below ) | +| RS_Payload | 9 | See R-MSG-RA ( used in Bmax calculation ) | +| RS_Overhead | 7 | See R-MSG-RA ( used in Bmax calculation ) | +| Nr_of_Tones | 8 | See R-MSG-RA ( used in Bmax calculation ) | +| Reserved | 32 | | +| } | | | + +Attenuation and Noise Margin are updated values based on the current modem conditions. + +Bmax indicates the maximum number of bits that can be carried per DMT symbol assuming a single latency and the Coding\_Gain, RS\_Payload, RS\_Overhead and Nr\_of\_Tones values listed. The same definitions as during RA at Start-Up apply. + +The Required SNR margin used for the derivation of Bmax coincides: + +- in the case of an autonomous *DRA\_Monitor\_Reply*, with the Required SNR Margin that was used during the configuration of the current, active configuration; +- in the case of a response to a *DRA\_Monitor\_Request*, with the Req\_SNR\_Margin listed in *DRA\_Monitor\_Request*. + +## II.4 Configuration + +Based on the gathered metrics and/or additional information, a network entity aware of the DRA policy may detect that the conditions are met, and modify the modem configuration. Two new AOC messages are defined to allow the ATU-C to propose one new configuration to the ATU-R for the DS. + +NOTE – No need for US information exchange at this stage. + +### II.4.1 DRA\_Configuration\_Request + +DRA\_Configuration\_Request is a concatenated message sent by the ATU-C. It consists of three 13-byte messages. The format of the messages is shown in Table II.4 (each field is one byte long). The definition of the messages is shown in Table II.5. + +**Table II.4/G.992.1 – DRA Configuration Request format** + +| | | | | | | | | | | | | | +|-------------------------|-------------------------|------------|------|------|------|-----|------------|------|------|-----|-----|------------| +| HDR
DF 16 | COM
42 16 | RSM | BFd | BFd | BFd | BFd | 0xF | BFd | BFd | BFu | BFu | BFu | +| HDR
DF 16 | COM
41 16 | RES | BIId | BIId | BIId | RES | BIId | BIId | BIId | BIu | BIu | BIu | +| HDR
D 16 | COM
40 16 | RES | RFd | RIId | Sd | Id | RES | RFd | RIId | Sd | Id | RES | + +**Table II.5/G.992.1 – DRA Configuration Request messages** + +| Message Fields | Definition | +|-----------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------| +| RSM | Required SNR Margin to be used for the evaluation of this configuration. Value in dB. The allowed values range from 0 to 15 dB (4 bits). | +| Bfd, Bfu, BIId, BIu, Rfd, RIId, Rfu, Riu, Sd, Su, Id, Iu | Same definitions and ordering as in C-Rates-RA apply | +| RES | Reserved bytes coded as FF 16 | + +#### II.4.2 DRA Configuration Reply + +This message shall be sent by the ATU-R in response to *DRA Configuration Request* from the ATU-C. The format and definition of the message are shown in Tables II.6 and II.7. + +**Table II.6/G.992.1 – DRA Configuration Reply format** + +| | | | | +|-------------------------|-------------------------|-----|-----| +| HDR
DF 16 | COM
60 16 | STA | DAT | +|-------------------------|-------------------------|-----|-----| + +**Table II.7/G.992.1 – DRA Configuration Reply messages** + +| Message Format | Bits | Definition | +|---------------------------|------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Configuration_Reply { | | | +| Header | 8 | DF 16 | +| Command | 8 | 60 16 | +| Status (STA) | 8 | 00 16 : Reserved
01 16 : ACK: New configuration accepted
02 16 : Retransmit: resend all DRA_Configuration_Request messages
03 16 : Option Fail: proposed option rejected
04 16 -FF 16 : Reserved | +| Data (DAT) | 8 | if STA=ACK: Noise margin for this configuration as in R-MSG2
if STA=RETRANSMIT: 00 16
if STA=OPTION_FAIL:
00 16 : General Failure Code
01 16 -1F 16 : Reserved for Specific Failure Codes | +| } | | | + +## II.5 Exchange + +Once both sides agree on the new configuration, both sides must be informed about which Bi and Gi to use on each tone. This is done in this third phase. + +For this purpose two additional DRA-AOC messages are defined: *DRA\_Exchange\_Request* and its reply *DRA\_Exchange\_Reply*. + +Unlike the previous DRA messages, the messages are used in both the downstream and upstream direction. For the Downstream the ATU-R is generating the *DRA\_Exchange\_Request* and the ATU-C answers with a *DRA\_Exchange\_Reply*. For the upstream the ATU-C generates the *DRA\_Exchange\_Request* and the ATU-R answers with *DRA\_Exchange\_Reply*. + +### II.5.1 DRA\_Exchange\_Request + +*DRA\_Exchange\_Request* is a concatenated message sent by the ATU-C. It consists of four 13-byte messages. + +This message is used to communicate the modified Bi and Gi of the respective communication direction. Because one set of four 13-byte messages may be insufficient to communicate all the modified values, a set of messages may be repeated for a new set of tones until all the new settings have been exchanged successfully. + +The format and definition of *DRA\_Exchange\_Request* are given in Tables II.8 and II.9. The 13-byte message consists of three bytes followed by eight 10-bit fields. Each of these 10-bit fields encodes the Bi&Gi value of one tone. + +**Table II.8/G.992.1 – DRA\_Exchange\_Request format** + +| | | | | | | | | | | | +|------------------|-----|----|--------|----------|----------|-----|----------|----------|----------|----------| +| HDR | COM | Ti | B&G | B&G | B&G | 111 | B&G | B&G | B&G | B&G | +| DF 16 | | | (Ti*8) | (Ti*8+1) | (Ti*8+2) | | (Ti*8+4) | (Ti*8+5) | (Ti*8+6) | (Ti*8+7) | + +For the upstream only one block of four 13-byte messages is needed. For the downstream a maximum of 8 blocks of four 13-byte messages are needed. + +The COM values of consecutive *DRA\_Exchange\_Request* messages are ordered as follows: + +- the COM values decrease by one for each consecutive message (assuming no retransmission is needed); +- the COM value of the last *DRA\_Exchange\_Request* message shall be 8016. + +For the upstream direction this means that 4 COM values that shall be used are –in order– 8316, 8216, 8116 and 8016. + +For the downstream direction the first COM value depends on how many blocks of four 13-byte messages are needed. In the case that the maximum of 8 blocks (256 tones) are needed, the consecutive COM-values shall be 9F16, 9E16 .... 8316, 8216, 8116 and 8016. If for example only 7 blocks (224 tones) are needed, then the first COM value shall be 9B16. + +A new block of 4 *DRA\_Exchange\_Request* messages is allowed to be sent out only after the previous block of 4 messages has successfully been acknowledged (see *DRA\_Exchange\_Reply*). + +**Table II.9/G.992.1 – DRA Exchange Request messages** + +| Message Format | Bits | Definition | +|----------------------------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Exchange_Request { | | | +| Header | 8 | DF 16 | +| Command | 8 | 9F 16 ... 80 16 (Downstream) 83 16 ... 80 16 (Upstream) | +| Tone Segment (Ti) | 5 | Tone segment (0-31) | +| Bi&Gi (B&G) | 8 × 10 | Bi and Gi values of 8 subsequent tones, starting from tone Ti.
Bi 4 bits  new Bi-value encoded as integer
Gi 6 bits  new Gi value:
00 16 : No Power
01 16 -3F 16 : –3.875 dB to 3.875 dB in steps of 0.125 dB
Notice that Gi must be ≤2.5 dB in order to be valid. | +| } | | | + +### II.5.2 DRA\_Exchange\_Reply + +This message shall be sent in response to a *DRA\_Exchange\_Request* message; its format and message definition are shown in Tables II.10 and II.11. + +**Table II.10/G.992.1 – DRA\_Exchange\_Reply format** + +| | | | | +|------------------|------------------|-----|-----| +| HDR | COM | STA | DAT | +| DF 16 | A0 16 | | | + +**Table II.11/G.992.1 – DRA\_Exchange\_Reply messages** + +| Message Format | Bits | Definition | +|-------------------------------------------|------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Exchange_Reply { | | | +| Header | 8 | DF 16 | +| Command | 8 | A0 16 | +| Status (STA) | 8 | 00 16 : Reserved
01 16 : ACK: New Bi-Gi configuration accepted
02 16 : Retransmit: resend last set of 4 DRA_Exchange_Request messages
03 16 : Option Fail: proposed option rejected
04 16 -FF 16 : Reserved | +| Data (DAT) | 8 | if STA=ACK: COM value of the last 13-byte message of the block of 4 that is being acknowledged.
if STA=RETRANSMIT: COM value of the last 13-byte message of the block of 4 that must be retransmitted.
if STA=OPTION_FAIL: 00 16 General Failure Code
01 16 -1F 16 reserved for Specific Failure Codes | +| } | | | +| NOTE – Upstream always 80 16 . | | | + +## II.6 Swap + +Once the modems have agreed on the appropriate settings for the new configuration, the swap to the new configuration must be activated and synchronized. A swap always refers to the most recently agreed and successfully exchanged rate configuration settings. + +Two new messages are defined: *DRA\_Swap\_Request* and *DRA\_Swap\_Reply*. *DRA\_Swap\_Request* will be sent by the ATU-C to inform the ATU-R about when to swap the rate. The ATU-R will acknowledge this request through the use of *DRA\_Swap\_Reply*. + +During the transition from one rate configuration to another, tones may be sent with the wrong Bi and Gi. This also applies to Synch symbols. Synch symbols may be corrupted. The pilot tone however must be maintained in order to allow frame and superframe detection. The transition time where the Bi and Gi may be corrupted is quantified prior to the actual rate swap through the use of two sets of parameters: + +- 1) A SuperFrame Reference Number (*SFR*) to identify around which superframe boundary the rate swap will occur. Valid values of *SFR* are: + +$SFR = 4 \times N - 1$ where *N* is an integer number. + +If the modems operate with the mandatory *S*-values, these *SFR*-references always coincide with codeword boundaries. This avoids an explicit Reset of the FEC-mechanism. However if a different *S*-value is used then a reset is mandatory. + +Notice that *SFR* equals zero at the first ShowTime symbol and is then increased by one (modulo 256) at each consecutive superframe. The definition of *SFR* is identical to the definition used for synchronizing a Bit-Swap operation. + +By analogy with the bit-swap specification, the *SFR* value shall at least exceed by 47 the superframe counter value that coincides with when the *DRA\_Swap\_Request* message is sent out. + +- 2) A second set of parameters will indicate how many symbols before and after the reference superframe boundary: +- the transmitter for the respective communication direction can send wrong constellation sizes and gains, therefore corrupting data; + - the receiver of the respective communication direction may not be able to recover the correct data. This value is not supposed to affect the speed at which the DRA swap is executed by the transmitter, but it allows to quantify the loss of data during a DRA. + +In total 8 duration values (e's) shall be exchanged. The e-values indicate the capability of the ATU's to adjust, fast or slow, to a change in Bi/Gi and FEC settings. Four e-values are sent out by the ATU-C to the ATU-R within the *DRA\_Swap\_Request* message. These are: + +- 1) *Eps\_DS\_TX\_neg* +- 2) *Eps\_DS\_TX\_pos* +- 3) *Eps\_US\_RX\_neg* +- 4) *Eps\_RX\_RX\_pos* + +The ATU-R in *DRA\_Swap\_Reply* shall send 4 analogous e-parameters: + +- 5) *Eps\_US\_TX\_neg* +- 6) *Eps\_US\_TX\_pos* +- 7) *Eps\_DS\_RX\_neg* +- 8) *Eps\_DX\_RX\_pos* + +The syntax of these fields relies on the following rules: + +- "DS/US" refers to the communication direction. +- "TX/RX" refers to whether the e-value refers to the transmitting or receiving function. +- "neg/pos" refers to whether the e-parameter identifies respectively the beginning – expressed in how many frames before the SFR reference – or the end – expressed in how many symbols after the SFR reference – of the timespan in which the data may be corrupted. + +Each ATU-x only indicates the e's that apply to its side. There is no negotiation process of e's involved. + +Each e-value is positive and encoded in one byte as an unsigned value indicating a duration ranging from 0 to 255 frames. + +- The maximum number of corrupted symbols (CS) for the downstream direction (incl. receiver) can be quantified as: + +$$CS_{DS} = \max(Eps\_DS\_TX\_neg, EPS\_DS\_RX\_neg) + \max(EPS\_DS\_TX\_pos, EPS\_DS\_RX\_pos)$$ + +- The maximum number of corrupted symbols for the upstream direction (incl. receiver) can be quantified as: + +$$CS_{US} = \max(Eps\_US\_TX\_neg, EPS\_US\_RX\_neg) + \max(Eps\_US\_TX\_pos, EPS\_US\_RX\_pos)$$ + +### II.6.1 Example + +Consider the situation shown in Figure II.1. + +![Figure II.1/G.992.1 – Corrupted frames transmitted by ATU-C. A horizontal timeline shows frames 66, 67, and 68 in grey boxes to the left of a vertical line labeled 'SFR'. To the right of the SFR line are frames 0, 1, 2, 3, and 4 in grey boxes. The timeline ends with an arrow and the label 'T1533250-99'.](97c091d05e2a8a17afd31a91f237e12d_img.jpg) + +Figure II.1/G.992.1 – Corrupted frames transmitted by ATU-C. A horizontal timeline shows frames 66, 67, and 68 in grey boxes to the left of a vertical line labeled 'SFR'. To the right of the SFR line are frames 0, 1, 2, 3, and 4 in grey boxes. The timeline ends with an arrow and the label 'T1533250-99'. + +**Figure II.1/G.992.1 – Corrupted frames transmitted by ATU-C** + +The grey zones represent the corrupted frames or DMT symbols that the ATU-C will transmit downstream during a DRA Swap. In this particular situation, *Eps\_DS\_TX\_neg* is equal to 2 (two zones are grey before SFR), and *Eps\_DS\_TX\_pos* is equal to 3 (three zones are grey after SFR). + +If the ATU-R receiver capability to adapt to the new configuration is identified by an *Eps\_DS\_RX\_neg* of 0, and an *Eps\_DS\_RX\_pos* of 5 (see Figure II.2), then the maximum number of corrupted symbols is 7. + +![Figure II.2/G.992.1 – Frames corrupted by the ATU-R receiver. A horizontal timeline shows frames 66, 67, and 68 in grey boxes to the left of a vertical line labeled 'SFR'. To the right of the SFR line are frames 0, 1, 2, 3, and 4 in grey boxes. The timeline has dashed lines at both ends and ends with an arrow and the label 'T1533260-99'.](c636e9b650fe8c661dec4486ffc434fd_img.jpg) + +Figure II.2/G.992.1 – Frames corrupted by the ATU-R receiver. A horizontal timeline shows frames 66, 67, and 68 in grey boxes to the left of a vertical line labeled 'SFR'. To the right of the SFR line are frames 0, 1, 2, 3, and 4 in grey boxes. The timeline has dashed lines at both ends and ends with an arrow and the label 'T1533260-99'. + +**Figure II.2/G.992.1 – Frames corrupted by the ATU-R receiver** + +### II.6.2 DRA\_Swap\_Request + +This message is sent by the ATU-C; its format and message definition are shown in Tables II.12 and II.13. + +**Table II.12/G.992.1 – DRA Swap Request Format** + +| | | | | | | | | +|------------------|------------------|-----|-----|------|------|------|------| +| HDR | COM | STA | DAT | EDTN | EDTP | EURN | EURP | +| DF 16 | C0 16 | | | | | | | + +**Table II.13/G.992.1 – DRA Swap Request messages** + +| Message Format | Bits | Definition | +|-----------------------------|------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Swap_Request { | | | +| Header | 8 | DF 16 | +| Command | 8 | C0 16 | +| Status (STA) | 8 | 00 16 : Reserved
01 16 : SWAP Request
02 16 : SWAP Information Request (Note)
03 16 -FF 16 : reserved | +| Data (DAT) | 8 | if STA=SWAP: SFR . Notice that the two least significant bits must be encoded as 3 16 .
if STA≠SWAP: Reserved | +| Eps_DS_TX_neg (EDTN) | 8 | See above | +| Eps_DS_TX_pos (EDTP) | 8 | See above | +| Eps_US_RX_neg (EURN) | 8 | See above | +| Eps_US_RX_pos (EURP) | 8 | See above | +| } | | | + +NOTE – Swap Information Request allows the ATU-C to retrieve the e's of the ATU-R and evaluate data loss without requesting a rate swap. + +### II.6.3 DRA\_Swap\_Reply + +This message is sent by the ATU-R as a reply to *DRA\_Swap\_Request*; its format and message definition are given in Tables II.14 and II.15. + +**Table II.14/G.992.1 – DRA Swap Reply Format** + +| | | | | | | | | +|------------------|------------------|-----|-----|------|------|------|------| +| HDR | COM | STA | DAT | EUTN | EUTP | EDRN | EDRP | +| DF 16 | E0 16 | | | | | | | + +**Table II.15/G.992.1 – DRA Swap Reply messages** + +| Message Format | Bits | Definition | +|-----------------------------|------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DRA_Swap_Reply { | | | +| Header | 8 | DF 16 | +| Command | 8 | E0 16 | +| Status (STA) | 8 | 00 16 : Reserved
01 16 : ACK SWAP
02 16 : NACK_SWAP
03 16 : ACK SWAP_INFO
04 16 : NACK SWAP_INFO
Other: Reserved | +| Data (DAT) | 8 | if STA=ACK: same SFR -value as DRA_Swap_Request
if STA≠ACK: Reserved | +| Eps_US_TX_neg (EUTN) | 8 | See above | +| Eps_US_TX_pos (EUTP) | 8 | See above | +| Eps_DS_RX_neg (EDRN) | 8 | See above | +| Eps_DS_RX_pos (EDRP) | 8 | See above | +| } | | | + +## II.7 DRA state diagram + +### II.7.1 State machine conventions + +When being in a particular state, only the messages shown in the diagram should be responded to. Any other message received should be ignored. + +Sharp-edged rectangles indicate states. Text covering an arrow indicates the condition for that arrow. Round-edged rectangles indicate actions to be taken along the arrows and maximum time (in ms) to perform that action. + +The grey states and transitions refer to the standardized Bit Swap mechanism. + +## II.7.2 ATU-R state machine + +See Figure II.3. + +![ATU-R state diagram for AOC. The diagram shows various states and transitions for an ATU-R device, centered around an 'IDLE' state. Transitions include RX config requests, RX exchange requests, TX monitor replies, TX DRA swap replies, and bit swap requests/replies with associated timeouts.](f6c1b4dbeaba413a5442ea2c6aa71337_img.jpg) + +The state diagram illustrates the ATU-R state machine for AOC. The central state is **IDLE**. Transitions from **IDLE** include: + +- RX config request 2** leads to a **wait** state with **timeout T=250**. From **wait**, **RX config request 1** leads to another **wait** state with **timeout T=250**. From this **wait**, **RX config request 0** leads to **TX config reply within T=4000**, which returns to **IDLE**. A **timeout T=250** from the first **wait** also returns to **IDLE**. +- RX exchange request (0, 3)** leads to a **wait** state with **timeout T=250**. From **wait**, **RX exchange request (0, 2)** leads to another **wait** state with **timeout T=250**. From this **wait**, **RX exchange request (0, 1)** leads to a third **wait** state with **timeout T=250**. From this **wait**, **RX exchange request (0, 0)** leads to **TX exchange reply within T=500**, which returns to **IDLE**. A **timeout T=250** from the first **wait** also returns to **IDLE**. +- RX DRA swap request** leads to **TX DRA swap reply within T=300**, which returns to **IDLE**. +- RX monitor request** leads to **TX monitor reply within T=4000**, which returns to **IDLE**. +- RX bit swap request** leads to **TX bit swap ack within T=300**, which returns to **IDLE**. + +Transitions to **IDLE** from other states: + +- TX monitor reply** returns to **IDLE**. +- TX DRA swap reply within T=300** returns to **IDLE**. +- TX bit swap request** (from a **wait** state with **timeout T=450**) returns to **IDLE**. +- TX bit swap ack within T=300** returns to **IDLE**. + +Internal transitions and logic: + +- From **RX exchange request (0, 0)**, the state machine enters a loop: **wait < 4000** → **i = N-1** → **TX exchange request [i,3210] within T=750** → **wait**. From **wait**, **RX RETR** loops back to **TX exchange request**, **RX ACK** returns to **IDLE**, and **RX FAIL or timeout** (with **T=700 if i>0** or **T=5000 if i=0**) returns to **IDLE**. A transition **i = i-1** with condition **if i>0** loops back to **TX exchange request**. A transition **if i=0** returns to **IDLE**. +- From **TX config reply within T=4000**, a transition **timeout T=250** returns to **IDLE**. +- From **TX exchange reply within T=500**, a transition **timeout T=250** returns to **IDLE**. + +Reference: T1533270-99 + +ATU-R state diagram for AOC. The diagram shows various states and transitions for an ATU-R device, centered around an 'IDLE' state. Transitions include RX config requests, RX exchange requests, TX monitor replies, TX DRA swap replies, and bit swap requests/replies with associated timeouts. + +Figure II.3/G.992.1 – ATU-R state diagram for AOC + +## II.7.3 ATU-C state machine + +See Figure II.4. + +![ATU-C state diagram for AOC](47ab805b7e6a0b6eb9e379fd8da934fa_img.jpg) + +The state diagram illustrates the ATU-C state machine for AOC, centered around an **IDLE** state. Transitions are triggered by various events and result in specific actions or states, often with associated timers. + +- From IDLE to TX monitor request:** Triggered by **timeout T=5000**. Action: **TX monitor request**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **RX monitor reply**. +- From IDLE to TX DRA swap request:** Triggered by **RX ACK or NACK**. Action: **TX DRA swap request**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **timeout T=500**. +- From IDLE to TX config request [210]:** Triggered by **RX RETR**. Action: **TX config request [210] within T=500**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **RX RETR** or **RX FAIL, ACK or timeout T=5000**. +- From IDLE to TX exchange request [0,3210]:** Triggered by **RX FAIL or timeout T=700**. Action: **TX exchange request [0,3210] within T=750**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **RX RETR** or **RX FAIL or timeout T=700**. A **timeout T=5000** from **wait** also leads to **IDLE**. +- From IDLE to RX exchange request (i, 3):** Triggered by **RX ACK**. Action: **RX exchange request (i, 3)**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **timeout T=250**. +- From RX exchange request (i, 3) to RX exchange request (i, 2):** Triggered by **RX exchange request (i, 2)**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **timeout T=250**. +- From RX exchange request (i, 2) to RX exchange request (i, 1):** Triggered by **RX exchange request (i, 1)**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **timeout T=250**. +- From RX exchange request (i, 1) to RX exchange request (i, 0):** Triggered by **RX exchange request (i, 0)**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **timeout T=250**. +- From RX exchange request (i, 0) to TX exchange reply:** Action: **TX exchange reply within T=500 if i>0 T=4000 if i=0**. Transition to **i = i-1** state if **i > 0**. If **i = 0**, transition back to **IDLE**. +- From i = i-1 to wait:** Action: **i = i-1**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **timeout T=750**. +- From IDLE to TX bit swap request:** Triggered by **timeout T=450**. Action: **TX bit swap request**. Transition to **wait** state. From **wait**, transition back to **IDLE** on **RX ACK**. +- From TX bit swap request to TX bit swap ack:** Action: **TX bit swap ack within T=300**. Transition to **RX bit swap request** state. From **RX bit swap request**, transition back to **IDLE**. + +T1533280-99 + +ATU-C state diagram for AOC + +Figure II.4/G.992.1 – ATU-C state diagram for AOC + +## APPENDIX III + +### Compatibility with other customer premises equipment + +G.992.1 ATU-R transceivers may share the CPE wiring plant with other equipment, e.g. networking devices, over the POTS splitter. + +Some networking devices can operate above 4 MHz on customer premises phone wiring. To prevent signals from such networking devices from aliasing into the G.992.1 frequency band, the inclusion of an adequate downstream receiver anti-aliasing filter in the G.992.1 ATU-R is recommended, collocated with the ATU-R in Figure 1-1. The filter may take the form of an external in-line filter, may be integrated into the G.992.1 ATU-R or may be integrated in the POTS splitter as specified in Annex E. + +Home networking devices may coexist with voice terminals and non-voice terminals on the TELE/POTS port side (the port in Figure 1-1 that attaches to the wire leading to the telephone set or voiceband modem) of the POTS splitter used in the G.992.1 application to isolate the customer premises wiring from the ADSL signal. It is desirable that the remote POTS splitter be compatible with other customer premises wiring devices (e.g. the TELE/POTS port impedance above 4 MHz should be considered). + +## APPENDIX IV + +### Bibliography + +- ITU-T Recommendation G.995.1 (1999), *Overview of Digital Subscriber Line (DSL) Recommendations*. +- ITU-T Recommendation O.41 (1994), *Psophometer for use on telephone-type circuits*. +- ITU-T Recommendation V.11 (1996), *Electrical characteristics for balanced double-current interchange circuits operating at data signalling rates up to 10 Mbit/s*. +- Technical Report No. 28 (1994), *A Technical Report on High-bit rate Digital Subscriber Lines*, Committee T1-Telecommunications. +- ATM Forum (June 1995), Specification af.phy-0039.000, *Utopia Level 2: Version 1.0*. +- ANSI/EIA/TIA-571 (1991), *Environmental considerations for telephone terminals*. +- ANSI T1.101 (1994), *Synchronization Interface Standards for Digital Networks*, Committee T1-Telecommunications, 1997. +- ANSI T1.413 (1995), *Network and Customer Installation Interfaces – Asymmetrical Digital Subscriber Line (ADSL) Metallic Interface*. +- ANSI T1.601 (1993), *Telecommunications – Interface between carriers and customer installations – Analogue voice-grade switched access lines using loop-start and ground-start signalling*. + +For test setup for measurement of longitudinal balance (for example E.2.3.2.2 and E.4.3.1.6), see: + +- IEEE Standard 455 (1985), *Test procedures for measuring longitudinal balance of telephone equipment operating in the voiceband*. + +For test setup for measurement of distortion caused by harmonics (for example E.4.3.1.5), see: + +- IEEE Standard 743 (1995), *IEEE Standard Equipment Requirements and Measurement Techniques for Analogue Transmission Parameters for Telecommunications*. + + + +## ITU-T RECOMMENDATIONS SERIES + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of the ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure | +| Series Z | Languages and general software aspects for telecommunication systems | + +\*17821\* \ No newline at end of file diff --git a/marked/G/T-REC-G.993.5-201902-I_PDF-E/036ceaf207a7b289ca76e160892eb724_img.jpg 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+|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# **Recommendation ITU-T G.993.5** + +# **Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers** + +## **Summary** + +Vectoring is a transmission method that employs the coordination of line signals for reduction of crosstalk levels and improvement of performance. The degree of improvement depends on the channel characteristics. Vectoring may be for a single user or for multiple users' benefit. + +Recommendation ITU-T G.993.5 is specifically limited to the self-far-end crosstalk (self-FEXT) cancellation in the downstream and upstream directions. It defines a single method of self-FEXT cancellation, in which FEXT generated by a group of near-end transceivers and interfering with the far-end transceivers of that same group is cancelled. This cancellation takes place between very high-bit-rate digital subscriber line 2 (VDSL2) transceivers, not necessarily of the same profile. This Recommendation is intended to be implemented in conjunction with Recommendation ITU-T G.993.2. + +This version of this Recommendation integrates all of the previous amendments and corrigenda with the 2015 version 2.0 of Recommendation ITU-T G.993.5. + +This version of Recommendation ITU-T G.993.5 corrects or adds the following functionality: + +- Typographical correction in clause 8.2 (Corrigendum 1) +- Generalization of the segmentation of SOC messages in clause 10.4.2.2 for vectoring of profile 35b (Corrigendum 1) +- Transceiver O-DEACTIVATING state (Amendment 1) +- Annex A: Mitigating strong FEXT (Amendment 2) +- Annex B: Vectored Long Reach VDSL2 (Amendment 2) +- Encoding of R-P-VECTOR-2 in LR mode with long loop operation (Annex B) (Corrigendum 2) +- Long reach VDSL2 corrigendum related to MAXNOMATP (new). + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.993.5 | 2010-04-22 | 15 | 11.1002/1000/10414 | +| 1.1 | ITU-T G.993.5 (2010) Cor. 1 | 2011-06-22 | 15 | 11.1002/1000/11128 | +| 1.2 | ITU-T G.993.5 (2010) Amd. 1 | 2011-12-16 | 15 | 11.1002/1000/11396 | +| 1.3 | ITU-T G.993.5 (2010) Cor. 2 | 2012-06-13 | 15 | 11.1002/1000/11643 | +| 1.4 | ITU-T G.993.5 (2010) Amd. 2 | 2012-10-29 | 15 | 11.1002/1000/11796 | +| 1.5 | ITU-T G.993.5 (2010) Amd. 3 | 2013-04-22 | 15 | 11.1002/1000/11889 | +| 1.6 | ITU-T G.993.5 (2010) Amd. 4 | 2013-08-29 | 15 | 11.1002/1000/11993 | +| 1.7 | ITU-T G.993.5 (2010) Amd. 5 | 2014-04-04 | 15 | 11.1002/1000/12095 | +| 2.0 | ITU-T G.993.5 | 2015-01-13 | 15 | 11.1002/1000/12372 | +| 2.1 | ITU-T G.993.5 (2015) Cor. 1 | 2016-11-13 | 15 | 11.1002/1000/13089 | +| 2.2 | ITU-T G.993.5 (2015) Amd. 1 | 2016-12-22 | 15 | 11.1002/1000/13121 | +| 2.3 | ITU-T G.993.5 (2015) Amd. 2 | 2017-12-07 | 15 | 11.1002/1000/13307 | +| 2.4 | ITU-T G.993.5 (2015) Cor. 2 | 2018-03-16 | 15 | 11.1002/1000/13529 | +| 3.0 | ITU-T G.993.5 | 2019-02-22 | 15 | 11.1002/1000/13748 | + +## Keywords + +Crosstalk Cancellation, Long Reach, VDSL2, Vectoring. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|----------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 3 | +| 5 | Reference models..... | 4 | +| 5.1 | General ..... | 4 | +| 5.2 | Downstream vectoring..... | 6 | +| 5.3 | Upstream vectoring ..... | 7 | +| 6 | CO-side requirements in a vectored group ..... | 7 | +| 6.1 | General ..... | 7 | +| 6.2 | Downstream vectoring requirements for the VTU-O..... | 8 | +| 6.3 | Upstream vectoring requirements for the VTU-O..... | 14 | +| 6.4 | Requirements for the VCE ..... | 14 | +| 7 | CP-side requirements in a vectored group..... | 14 | +| 7.1 | General ..... | 15 | +| 7.2 | Downstream vectoring requirements for the VTU-R..... | 16 | +| 7.3 | Upstream vectoring requirements for the VTU-R..... | 26 | +| 7.4 | Requirements for the NT system..... | 27 | +| 8 | Vectoring-specific eoc messages..... | 28 | +| 8.1 | eoc messages for backchannel configuration ..... | 29 | +| 8.2 | Pilot sequence update command and response..... | 33 | +| 8.3 | Power management commands and responses..... | 35 | +| 9 | Activation and deactivation of pairs in a vectored group ..... | 36 | +| 9.1 | Orderly shutdown event ..... | 36 | +| 9.2 | Disorderly shutdown event..... | 36 | +| 10 | Initialization of a vectored group..... | 36 | +| 10.1 | Overview ..... | 36 | +| 10.2 | ITU-T G.994.1 Handshake phase ..... | 40 | +| 10.3 | Channel Discovery phase ..... | 46 | +| 10.4 | Training phase ..... | 56 | +| 10.5 | Channel Analysis and Exchange phase ..... | 66 | +| 10.6 | Transition from initialization to Showtime ..... | 66 | +| 10.7 | Loop diagnostic mode procedures..... | 67 | +| 11 | Configuration and test parameters ..... | 69 | +| 11.1 | Configuration parameters ..... | 69 | + +| | Page | +|---------------------------------------------------------------------------------------------------------------------------------|-------------| +| 11.2 Test parameters..... | 71 | +| Annex A – Mitigating strong FEXT ..... | 76 | +| A.1 Introduction ..... | 76 | +| A.2 Control parameters for the minimum message overhead data rate (amends clause 9.5.4 of [ITU-T G.993.2])..... | 76 | +| A.3 Clipped error samples..... | 76 | +| A.4 OLR commands..... | 77 | +| A.5 ITU-T G.994.1 Handshake phase (amends clause 10.2)..... | 78 | +| A.6 TIGAV functionality ..... | 79 | +| A.7 Main body amendments related to MREFPSD ..... | 88 | +| A.8 Management ..... | 100 | +| Annex B – Vectored long reach VDSL2 ..... | 102 | +| B.1 Introduction ..... | 102 | +| B.2 Overview of the initialization procedure ..... | 102 | +| B.3 ITU-T G.994.1 Handshake phase ..... | 104 | +| B.4 Signals sent by the VTU-O during the Channel Discovery and Training phase ..... | 109 | +| B.5 Signals sent by the VTU-R during the Channel Discovery and Training phase ..... | 113 | +| B.6 O/R-P-PROBING-LR signal exchange..... | 115 | +| B.7 O/R-P-TRAINING-LR signal exchange ..... | 121 | +| B.8 ITU-T G.993.5 Channel Discovery phase and Training phase in long loop operation ..... | 129 | +| B.9 Definition of limit PSD masks ..... | 131 | +| B.10 Management ..... | 131 | +| B.11 Nominal aggregate transmit power (NOMATP) (replaces clause 10.3.4.2.1 of [ITU-G.993.2])..... | 134 | +| Appendix I – Crosstalk channel modelling..... | 135 | +| I.1 Scope ..... | 135 | +| I.2 Purpose ..... | 135 | +| I.3 MIMO crosstalk channel model A ..... | 135 | +| I.4 MIMO crosstalk channel model C ..... | 135 | +| Appendix II – Examples of VCE control of initialization process in the activation of multiple lines in the vectored group ..... | 139 | +| II.1 Introduction ..... | 139 | +| II.2 VCE handling two groups of initializing lines ..... | 139 | +| II.3 VCE using handshake capabilities ..... | 142 | +| Appendix III – SNR-based FEXT channel estimation method..... | 143 | +| III.1 Tools ..... | 143 | +| III.2 Estimation of FEXT channels from a new line into existing lines..... | 143 | + +| | Page | +|-------------------------------------------------------------------------------|------| +| III.3    Estimation of FEXT channels from existing lines into a new line..... | 149 | +| Bibliography..... | 154 | + +# Recommendation ITU-T G.993.5 + +# Self-FEXT cancellation (vectoring) for use with VDSL2 transceivers + +# 1 Scope + +Vectoring is a transmission method that employs the coordination of line signals for reduction of crosstalk levels and improvement of performance. The degree of improvement depends on the channel characteristics. Vectoring may be for a single user or for multiple users' benefit. + +This Recommendation is specifically limited to the self-far-end crosstalk (self-FEXT) cancellation in the downstream and upstream directions. This Recommendation defines a single method of self-FEXT cancellation, in which far-end crosstalk (FEXT) generated by a group of near-end transceivers and interfering with the far-end transceivers of that same group is cancelled. This cancellation takes place between very high-bit-rate digital subscriber line 2 (VDSL2) transceivers, not necessarily of the same profile. This Recommendation is intended to be implemented in conjunction with [ITU-T G.993.2]. Multi-pair digital subscriber line (DSL) bonding ([b-ITU-T G.998.1], [b-ITU-T G.998.2] and [b-ITU-T G.998.3]) may be implemented in conjunction with vectoring. + +The techniques described in this Recommendation provide means of reducing self-FEXT generated by the transceivers in a multi-pair cable or cable binder. Self-FEXT cancellation techniques are particularly beneficial with short cable lengths ( $< 1$ km) and limited near-end crosstalk (NEXT), background noise, and FEXT from systems which are not a part of the vectored group (alien noise). The level of non-self-FEXT noise sources relative to that of self-FEXT sources determines the degree to which self-FEXT reduction can improve performance. Another significant factor is the degree to which the self-FEXT cancelling system has access to the disturbing pairs of the cable. Maximum gains are achieved when the self-FEXT cancelling system has access to all of the pairs of a cable carrying broadband signals. For multi-binder cables, significant gains are possible when the self-FEXT cancelling system has access to all of the pairs of the binder group(s) in which it is deployed and has the ability to cancel at least the majority of dominant self-FEXT disturbers within the binder. When multiple self-FEXT cancelling systems are deployed in a multi-binder cable without binder management, gains may be significantly reduced. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.993.2] Recommendation ITU-T G.993.2 (2019), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [ITU-T G.994.1] Recommendation ITU-T G.994.1 (2018), *Handshake procedures for digital subscriber line transceivers*. +- [ITU-T G.997.1] Recommendation ITU-T G.997.1 (2019), *Physical layer management for digital subscriber line transceivers*. +- [ITU-T G.998.4] Recommendation ITU-T G.998.4 (2018), *Improved impulse noise protection for digital subscriber line (DSL) transceivers*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation adopts the definitions of [ITU-T G.993.2]. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 backchannel:** The channel through which the VTU-R sends clipped error samples to the vectoring control entity (VCE). The backchannel may be implemented as part of the eoc or as part of the Ethernet data stream from the VTU-R to the VTU-O. + +**3.2.2 ceiling:** Rounding to the nearest higher integer, denoted as $\lceil x \rceil$ . + +**3.2.3 channel matrix:** For a particular line in a group of lines, the channel matrix characterizes the FEXT couplings on each subcarrier frequency between the line and all other lines in the group. + +**3.2.4 clipped error sample:** A $(B\_max+1)$ -bit 2's complement representation of a normalized error sample through multiplying each component by $2^{N\_max-1}$ , flooring and clipping to the $[-2^{B\_max}, 2^{B\_max}-1]$ interval (with $N\_max$ a fixed value, and $B\_max$ a value controlled by the VCE). + +**3.2.5 expected throughput (ETR):** see clause 3.2 of [ITU-T G.998.4]. + +**3.2.6 flag tones:** All subcarriers of a sync symbol with indices equal to $10n+1$ or $10n+7$ , with $n$ an integer value. Flag tones are used to signal OLR transitions during Showtime. + +**3.2.7 flooring:** Rounding to the nearest lower integer, denoted as $\lfloor x \rfloor$ . + +**3.2.8 normalized error sample:** The complex error measured by the VTU-R, being the distance between the received signal vector and the decision constellation point referred to the input of the constellation descrambler, expressed in units equal to half the distance between two adjacent constellation points. + +**3.2.9 pilot sequence:** A binary sequence set by the VCE. When the pilot sequence is transmitted during initialization and in Showtime, each bit of the pilot sequence determines whether the VTU-O (downstream pilot sequence) or the VTU-R (upstream pilot sequence), respectively, modulates ZEROs on all probe tones or ONEs on all probe tones of a particular sync symbol. + +**3.2.10 probe tones:** All subcarriers of a sync symbol with indices equal to $10n$ , $10n+2$ , $10n+3$ , $10n+4$ , $10n+5$ , $10n+6$ , $10n+8$ , or $10n+9$ , with $n$ an integer value. Probe tones are used for transmission of pilot sequences. + +**3.2.11 Syncflag:** A sync symbol in which the sync frame bits modulated on the flag tones are inverted relative to the sync frame modulated by the most recently transmitted sync symbol (i.e., if the previous sync frame was all ZEROs modulated on the flag tones, the Syncflag would correspond to a sync frame of all ONEs modulated on the flag tones, and vice versa). The Syncflag is used to signal online reconfiguration transitions. + +**3.2.12 vectored group:** The set of lines over which transmission from the access node (AN) is eligible to be coordinated by pre-compensation (downstream vectoring), or over which reception at the AN is eligible to be coordinated by post-compensation (upstream vectoring), or both. + +Depending on the configuration of the vectored group, downstream vectoring, upstream vectoring, both or none may be enabled. + +**3.2.13 vectoring:** The coordinated transmission and/or coordinated reception of signals of multiple DSL transceivers using techniques to mitigate the adverse effects of crosstalk to improve performance. + +# 4 Abbreviations and acronyms + +This Recommendation adopts the abbreviations defined in [ITU-T G.993.2]. In addition, this Recommendation uses the following abbreviations: + +| | | +|----------|-------------------------------------------------| +| ACTATP | Actual Aggregate Transmit Power | +| AFE | Analogue Front End | +| AN | Access Node | +| ATP | Aggregate Transmit Power | +| BDR | Backchannel Data Rate | +| CO | Central Office | +| CO-MIB | Central Office-Management Information Base | +| CO-side | End of the line nearer to the Central Office | +| CP | Customer Premises | +| CP-side | End of the line nearer to the Customer Premises | +| DMT | Discrete Multi-Tone | +| DSE | Disorderly Shutdown Event | +| DSL | Digital Subscriber Line | +| EC | Echo Canceller | +| eoc | Embedded Operation Channel | +| ERB | Error Report Block | +| ETR | Expected Throughput | +| FEXT | Far-end crosstalk | +| HDLC | High-Level Data Link Control | +| IDFT | Inverse Discrete Fourier Transform | +| L2+ | Ethernet Layer 2 and above | +| ME | Management Entity (or Mean Error) | +| MIMO | Multiple Input Multiple Output | +| NEXT | Near-end crosstalk | +| NDR | Net Data Rate | +| NMS | Network Management System | +| NOMATPds | Nominal Aggregate Transmit Power in downstream | +| NOMATPus | Nominal Aggregate Transmit Power in upstream | +| NT | Network Termination | + +| | | +|----------|---------------------------------------------------------------------------------------------| +| PCB | Power Cut-Back | +| PDF | Probability Density Function | +| PDM | Physical Medium Dependent | +| PSD | Power Spectral Density | +| QAM | Quadrature Amplitude Modulation | +| OLR | On-Line Reconfiguration | +| ONU | Optical Network Unit | +| QLN | Quiet Line Noise | +| RT | Remote Terminal | +| RTX | Retransmission | +| SC | Segment Code | +| SNR | Signal-to-Noise Ratio | +| SOC | Special Operations Channel | +| SOS | Save Our Showtime | +| SRA | Seamless Rate Adaptation | +| SSC | Sync Symbol Counter | +| TA | Timing Advance | +| TEQ | Time Domain Equalizers | +| TID | TIGAV identification number | +| TIGAV | Transmitter Initiated Gain Adjustment for VDSL2 | +| UPBO | Upstream Power Back Off | +| VBB | Vectored Band Block | +| VCE | Vectoring Control Entity | +| VDSL2 | Very high-bit-rate Digital Subscriber Line 2 | +| VDSL2-LR | Long Reach mode for Vectored VDSL2 | +| VME | VDSL2 Management Entity | +| VTU | Very high-speed digital subscriber line Transceiver Unit | +| VTU-O | VTU at the ONU (or central office, exchange, cabinet, etc., i.e., operator end of the loop) | +| VTU-R | VTU at the Remote site (i.e., subscriber end of the loop) | +| XTU-C | X digital subscriber line Transceiver Unit at the Central office | +| XTU-R | X digital subscriber line Transceiver Unit at the Remote end | + +# 5 Reference models + +## 5.1 General + +A reference model for a vectored system is illustrated in Figure 5-1. In a vectored system, the access node (AN), located at a central office (CO) or remote terminal (RT) or other location, transmits to and receives from a number of network terminations (NTs). The common element of all + +forms of vectoring is coordinated transmission (downstream vectoring) or coordinated reception (upstream vectoring) of signals from lines in the vectored group at the AN. Thus, the signals may be represented as a vector where each component is the signal on one of the lines. This coordination is made possible through an interface between a very high-speed digital subscriber line transceiver unit (VTU) at the ONU (VTU-O) (here called VTU-O-1) and all other VTU-Os (here called VTU-O- $n$ , $n=2\dots N$ , where $N$ denotes the number of lines in the vectored group), which is here called $\varepsilon-1-n$ to indicate that the coordination takes place between line 1 and line $n$ . + +Coordinated management of the lines is performed by the network management system (NMS), passing management information to the management entity (ME) through the Q-interface (see clause 11). Both the NMS and the ME are defined in [ITU-T G.997.1]. Inside the AN, the ME further conveys the management information for a particular line (over an interface here called $\varepsilon-m$ ) to the vectoring control entities (VCEs) of the vectoring group that line belongs to. Each VCE controls a single vectored group, and controls VTU-O- $n$ (connected to line $n$ in the vectored group) over an interface here called $\varepsilon-c-n$ . Pre-coder data are exchanged between VTU-O- $n1$ and VTU-O- $n2$ over an interface here called $\varepsilon-n1-n2$ . + +Figure 5-1 shows the reference model for a vectored system (only line 1 out of a vectored group of $N$ lines is shown). The PHY blocks represent the physical layer of the AN interface towards the network and of the NT interface towards the customer premises (CP). These blocks are shown for completeness of the data flow but are out of scope of this Recommendation. The Ethernet layer 2 and above (L2+) blocks represent the Ethernet Layer 2 and above functionalities contained in the AN and NT. These blocks are shown for completeness of the data flow but are out of scope of this Recommendation, except for the encapsulation (at NT) and decapsulation (at AN) of the backchannel (see clause 7.4.1). + +![Figure 5-1: Reference model for a vectored system (shown for line 1 in a vectored group of N lines).](ff0952ef692c9d960ce5f6708bcc9711_img.jpg) + +``` + +graph LR + subgraph AN [Access Network] + NMS -- Q --> ME_AN[ME] + ME_AN -- ε-m --> VCE + PHY_AN[PHY] --- L2_AN[L2+] + L2_AN --- VTUO1[VTU-O-1] + VCE -- ε-c-1 --> VTUO1 + VCE -- ε-c-n --> VTUOn[to VTU-O-n, n=2...N] + VCE -- ε-1-n --> VTUOn + end + + VTUO1 -- U-O --- UR[U-R] + + subgraph NT1 [NT-1] + UR --- VTUR1[VTU-R-1] + VTUR1 --- L2_NT[L2+] + L2_NT --- PHY_NT[PHY] + ME_NT[ME] --- VTUR1 + end + + PHY_NT --- G1[G-1] + G1 --- TS[T/S] + +``` + +Figure 5-1: Reference model for a vectored system (shown for line 1 in a vectored group of N lines). + +**Figure 5-1 – Reference model for a vectored system (shown for line 1 in a vectored group of $N$ lines)** + +Using [b-ITU-T G.998.1], [b-ITU-T G.998.2] and [b-ITU-T G.998.3], data rates can be increased by deploying multiple lines to the same customer premises – a technique known as bonding. + +NOTE – Vectoring is not another name for bonding; bonding may be used with or without vectoring. The use of vectoring over bonded lines is often defined as bonded vectoring or as multiple input multiple output (MIMO) DSL. + +The focus of this Recommendation is the use of vectoring over lines that are not bonded, although it does not preclude the use of vectoring over bonded lines. + +A vectored VDSL2 system improves its performance from the use of joint signal processing in the downstream direction (coordinated transmission), or from the use of joint signal processing in the upstream direction (coordinated reception) which allows cancelling of self-FEXT (i.e., FEXT generated by the lines of the vectored group). The noise sources which are external to the group of vectored pairs in the vectored system (for example, alien crosstalk from lines operated by another service provider, interference from AM broadcast channels or interference from amateur radio ("HAM") transmitters above the AM broadcast band) reduce the benefits of FEXT cancellation and reduce the performance enhancement provided by a vectored system. + +## 5.2 Downstream vectoring + +For relatively short lines and high-bandwidth systems such as VDSL, self-FEXT is the limiting factor for downstream data rates. This Recommendation defines multi-line pre-coding at the AN to mitigate FEXT in the downstream direction, based on "pre-subtraction" or "pre-compensation" of the FEXT, while meeting transmitted power constraints. To accommodate for such pre-coding, the [ITU-T G.993.2] physical medium dependent (PMD) layer is modified as shown in Figure 5-2 (adapted from Figure 10-1 of [ITU-T G.993.2], with differences shown shaded). Figure 5-2 shows the VTU-O functional model for line 1 out of a vectored group of $N$ lines. For each line in the vectored group, the PMD sublayer includes an $N \times 1$ pre-coder. Over the vectored group, the $N$ pre-coders for each of the $N$ lines constitute the FEXT cancellation pre-coder shown in Figure 6-1. + +NOTE – The pre-coder may or may not be implemented in the same physical device as the other functional blocks shown in Figure 5-2. + +![Figure 5-2: VTU-O functional model of PMD sub-layer using N x 1 pre-coder for downstream vectoring.](bd671b21db63e6fdb2196e9b18502aac_img.jpg) + +The diagram illustrates the functional model of the PMD sub-layer for line 1 in a vectored group of $N$ lines. The signal flow is as follows: + +- VTU-O-1 PMS-TC** (shaded label) is at the **δ reference point**. It receives a **Data frame (input)** and sends a **Data frame (output)**. +- The **Data frame (input)** is processed by three encoders: **Data symbol encoder (10.3/ITU-T G.993.2)**, **Sync symbol encoder (10.5/ITU-T G.993.2)**, and **Initialization symbol encoder (10.6/ITU-T G.993.2)**. +- These encoders feed into the **Pre-coder ( $N \times 1$ )** (shaded). The pre-coder also receives inputs **$\varepsilon$ -c-1 (input)** and **$\varepsilon$ -1- $n$ (input) ( $Z_i$ from VTU-O- $n$ , $n=2 \dots N$ )**. A signal **$Z$** is shown entering the pre-coder area. +- The output of the pre-coder is **$Z'$** , which feeds into the **Modulation (10.4/ITU-T G.993.2)** block. +- This block contains sub-processes: **Modulation by IDFT (10.4.3/ITU-T G.993.2)**, **Cyclic extension (10.4.4/ITU-T G.993.2)**, and **Windowing (10.4.4/ITU-T G.993.2)**. +- The output of the windowing block goes to a **Hybrid** block. +- The Hybrid block is connected to the **U-O reference point**. +- For reception, the signal from the Hybrid block goes through a **Demodulation** block (dashed) and then a **Decoder** block to produce the final **Data frame (output)**. +- The **VTU-O-1 PMD** (shaded label) block encompasses the Pre-coder, Modulation, and Demodulation blocks. + +Figure 5-2: VTU-O functional model of PMD sub-layer using N x 1 pre-coder for downstream vectoring. + +G.993.5(15)\_F5-2 + +**Figure 5-2 – VTU-O functional model of PMD sub-layer using $N \times 1$ pre-coder for downstream vectoring (shown for line 1 in vectored group of $N$ lines)** + +The VTU at the remote site (VTU-R) functional model of PMD sublayers is as shown in Figure 10-1 of [ITU-T G.993.2], with an addition of vectoring-related control signals applied to the sync symbol encoder and initialization symbol encoder to provide pilot sequence modulation on sync symbols, similar to those shown in Figure 5-2 (see clauses 10.3 and 10.4). + +## 5.3 Upstream vectoring + +Upstream vectoring is mainly a receiver function at the end of the line nearer to the central office (CO-side), and therefore its implementation is vendor discretionary. This Recommendation only defines the VTU-R transmitter requirements to facilitate upstream FEXT cancellation at the CO-side (e.g., transmission of upstream pilot sequence with timing and content under VCE control). + +# 6 CO-side requirements in a vectored group + +This clause describes the CO-side steady-state behaviour to support operation of an $N$ -pair vectored group. + +## 6.1 General + +Figure 6-1 shows the functional model for the inclusion of downstream FEXT cancellation pre-coding at the AN for all lines in the vectored group, as a generalization of Figure 5-2 from a signal processing perspective. The model shows only the portion of an array of the downstream symbol encoders (which represent the data, sync or initialization symbol encoders shown in Figure 5-2) and the modulation by the inverse discrete Fourier transform (IDFT) functional blocks of the VTU-Os, with the FEXT cancellation pre-coder inserted between the symbol encoders and the modulation by the IDFT blocks. + +The VCE of the vectored group learns and manages the channel matrix per vectored subcarrier, which reflects the channel characteristics of the managed group of lines. In the functional model in Figure 6-1, the channel matrix for each vectored subcarrier is of size $N \times N$ where $N$ is the number of lines in the vectored group. + +From the channel matrix, a FEXT pre-coder matrix may be derived and used to compensate the FEXT from each line in the vectored group. In the functional model in Figure 6-1, this is shown by a matrix of FEXT cancellation pre-coders per vectored subcarrier of size $N \times N$ . This FEXT cancellation pre-coding matrix may be "sparse" (see Note). Knowing the transmit symbols on each disturbing channel, the pre-coder pre-compensates the actual transmit symbol such that at the far-end receiver input, the crosstalk is significantly reduced. + +NOTE – In typical cases, several of the pre-coder coefficients may be set to 0 for implementation reasons, or because the crosstalk coefficients are negligibly small. + +The channel matrix and the resulting FEXT cancellation pre-coder matrix are assumed to be entirely managed inside the AN. An information exchange between the VTU-O and VTU-R is required in each vectored line to learn, track, and maintain the channel matrix and associated FEXT cancellation pre-coder matrix (see backchannel definition in clause 7 and initialization in clause 10). The actual algorithms for processing this information to obtain the channel matrix and to generate the FEXT cancellation pre-coder are vendor discretionary. Depending on the implementation, it may be possible for the VCE to directly determine the FEXT cancellation pre-coder matrix and only have an implicit learning of the channel matrix. + +![Figure 6-1: Vectored group functional model of PMD sub-layer using N x N pre-coder for downstream vectoring. The diagram shows N VTU-O units (VTU-O #1 to VTU-O #N) in a 'Vectored group of N lines'. Each VTU-O contains a 'Symbol encoder' producing Z_i, which is then processed by a 'Pre-coder' (N x 1) and 'Modulation by IDFT' to produce 'Line #i'. A central 'FEXT cancellation pre-coder (N x N) per sub-carrier' block is connected to all pre-coders. Red dashed arrows indicate cross-talk cancellation signals from the pre-coder outputs back to the symbol encoders, labeled with coefficients like ε-1-n, ε-2-n, and ε-N-n. Below the main block, a 'Management entity in AN (ME)' and 'Management entities in transceivers (VMEs)' are connected to a 'Vectoring control entity (VCE) channel matrix (N x N) per sub-carrier'. The VCE is also connected to 'Backchannel line #1', 'Backchannel line #2', and 'Backchannel line #N'. A double-headed arrow labeled ε-m connects the ME to the VCE, and another labeled ε-c connects the VCE to the backchannels. A note at the bottom states: 'Symbol encoder represents the data, sync or initialization symbol encoder shown in Figure 5-2.' and 'G.993.5(15)_F6-1'.](fa859e4e468bfb2710a94527f2c504af_img.jpg) + +Figure 6-1: Vectored group functional model of PMD sub-layer using N x N pre-coder for downstream vectoring. The diagram shows N VTU-O units (VTU-O #1 to VTU-O #N) in a 'Vectored group of N lines'. Each VTU-O contains a 'Symbol encoder' producing Z\_i, which is then processed by a 'Pre-coder' (N x 1) and 'Modulation by IDFT' to produce 'Line #i'. A central 'FEXT cancellation pre-coder (N x N) per sub-carrier' block is connected to all pre-coders. Red dashed arrows indicate cross-talk cancellation signals from the pre-coder outputs back to the symbol encoders, labeled with coefficients like ε-1-n, ε-2-n, and ε-N-n. Below the main block, a 'Management entity in AN (ME)' and 'Management entities in transceivers (VMEs)' are connected to a 'Vectoring control entity (VCE) channel matrix (N x N) per sub-carrier'. The VCE is also connected to 'Backchannel line #1', 'Backchannel line #2', and 'Backchannel line #N'. A double-headed arrow labeled ε-m connects the ME to the VCE, and another labeled ε-c connects the VCE to the backchannels. A note at the bottom states: 'Symbol encoder represents the data, sync or initialization symbol encoder shown in Figure 5-2.' and 'G.993.5(15)\_F6-1'. + +**Figure 6-1 – Vectored group functional model of PMD sub-layer using $N \times N$ pre-coder for downstream vectoring** + +The VTU-O shall support downstream vectoring (see clause 6.2) and may support upstream vectoring (see clause 6.3). + +The VTU-O shall support seamless rate adaptation ((SRA), on-line reconfiguration (OLR) Type 3) in the downstream and upstream direction, including mandatory support within SRA of: + +- dynamic interleaver reconfiguration (change of $D_p$ ); +- framing reconfiguration (change of $T_p$ , $G_p$ and $B_{p0}$ ) + +as defined in clause 13.1 of [ITU-T G.993.2]. + +If [ITU-T G.998.4] is enabled in a particular direction, the VTU-O shall also support seamless rate adaptation (SRA, OLR Type 5) in this same direction, including mandatory support within SRA of all configurations specified in clause C.3.2 of [ITU-T G.998.4]. + +## 6.2 Downstream vectoring requirements for the VTU-O + +The VTU-O shall comply with [ITU-T G.993.2], with the exceptions and additional requirements contained in this Recommendation. + +In order to enable the VCE to fulfil the tasks described in clause 6.1, the VTU-O shall support the requirements in this clause and the following clauses. + +### 6.2.1 Synchronous mode + +Under VCE control, all VTU-Os in the vectored group shall use the same subcarrier spacing and symbol rate, and shall start transmission of discrete multi-tone (DMT) symbols at the same time on all of the lines in the vectored group. The transmit symbol clocks shall be phase-synchronous at all VTU-Os in the vectored group with a 1 $\mu\text{s}$ maximum phase error tolerance at the U-O2 reference point (defined in Figure 5-4 of [ITU-T G.993.2]). + +### 6.2.2 Sync symbol position + +The VTU-O shall have the capability to transmit sync symbols as defined in clause 10.2 of [ITU-T G.993.2]. The downstream sync symbol time positions are determined by the VCE. The VCE may configure all VTU-Os in the vectored group to transmit downstream sync symbols at the same time positions or use different time positions for one or more VTU-Os in the vectored group. + +The VTU-O shall keep a downstream sync symbol counter (SSC) (MODULO $N\_SSC$ ), counting continuously during Showtime. The value $N\_SSC$ shall be selected by the VCE and transmitted during initialization to the VTU-R in O-SIGNATURE (see clause 10.3.2.1). The counter value of the first downstream sync symbol transmitted after entering Showtime shall be set by the VCE and transmitted to VTU-R in the field First SSC of the Error Feedback command (see Table 8-3). + +NOTE – This setting at the start of Showtime synchronizes the downstream sync symbol counter with the VTU-R (see clause 7.3.3). + +### 6.2.3 Modulation of a pilot sequence + +The VTU-O shall have the capability to modulate a VCE-specified downstream pilot sequence on all probe tones of the downstream sync symbols during initialization (see e.g., clause 10.3.3.1) and on all probe tones (see clause 3.2.10) of the downstream sync symbols during Showtime. The downstream pilot sequence is vendor discretionary, determined by the VCE, and is a binary string of length $Npilot\_ds$ (with bits indexed from 0 to $Npilot\_ds - 1$ , and the bit with index 0 transmitted first). If the "pilot sequence length multiple of 4" is enabled (see clause 10.2), then valid values of $Npilot\_ds$ are all multiples of 4 in the range from 8 to 512. Otherwise, the valid values of $Npilot\_ds$ shall be all powers of 2 in the range from 8 to 512. The pilot sequence shall be cyclically repeated after $Npilot\_ds$ bits, except the case where the downstream pilot sequence is changed by the VCE. The downstream pilot sequence bits may be changed by the VCE at any time without notification to the VTU-R, while maintaining the length of the pilot sequence. During initialization, the VTU-O may modulate on all flag tones of the downstream sync symbols either the downstream pilot sequence (the same as modulated on the probe tones), or an all ONEs sequence. + +In Showtime, the first downstream sync symbol position shall be as defined in clause 10.6. Each sync symbol shall modulate a pilot sequence, which may be frequency independent or frequency dependent. + +The modulation of a frequency independent pilot sequence on the probe tones of sync symbols is defined as whether the sync frame bits modulated onto the probe tones are set to all ZEROs (if the pilot sequence bit is ZERO) or set to all ONEs (if the pilot sequence bit is ONE) (i.e., a 1-bit control per sync symbol). + +The modulation of a frequency dependent pilot sequence on a probe tone of sync symbols is defined as whether the sync frame bits modulated onto the probe tone shall be set to either 00 (if the pilot sequence bit for that probe tone is ZERO) or set to 11 (if the pilot sequence bit for that probe tone is ONE). Over the tones of a particular sync symbol, the pilot sequence bit shall have a periodicity of 10 tones (considering both probe and flag tones). + +The sync frame bits modulated on the flag tones (see clause 3.2.6) shall be used for the transmission of a Syncflag as defined in clause 10.5.3 of [ITU-T G.993.2]. The sync frame shall be modulated onto a sync symbol as defined in clause 10.5 of [ITU-T G.993.2] (including the quadrant scrambling of all MEDLEY subcarriers, regardless of being a flag or probe tone). + +### 6.2.4 Pre-coding + +A VTU-O, when enabled for downstream vectoring, shall support FEXT cancellation pre-coding, as shown in Figure 5-2 and Figure 6-1. The pre-coding coefficients for each individual VTU-O (see clause 6.1) shall be under VCE control. + +### 6.2.5 Transceiver states and transceiver state diagram (replaces clause 12.1.2 of [ITU-T G.993.2]) + +NOTE 1 – This clause replaces clause 12.1.2 of [ITU-T G.993.2] as applicable to the VTU-O. Transceiver states and transceiver state diagram requirements as applicable to the VTU-R are unchanged. + +State diagrams are given in Figure 6-2 for the VTU-O and in Figure 12-3 of [ITU-T G.993.2] for the VTU-R. States are indicated by ovals, with the name of the state given within the oval. The states are defined in Table 6-1 for the VTU-O and in Table 12-2 of [ITU-T G.993.2] for the VTU-R. Transitions between states are indicated by arrows, with the event causing the transition listed next to the arrow. All states are mandatory. + +A variety of "host controller" commands (events preceded by "c:" and "r:") are shown in either state diagram to provide example events and transitions between states. The way in which these events are implemented is left to the vendor. + +In the state diagram for the VTU-O, an O-IDLE state is intended to establish a quiet mode, that is necessary to allow to discontinue service or to perform certain tests (e.g., as defined in [ITU-T G.996.2]). + +In the state diagram for the VTU-R, a self-test function is desirable, but it may be a vendor/customer option to define when self-test occurs (e.g., always at power-up or only under VTU-O control), and which transition to take after successfully completing self-test (e.g., enter R-IDLE, or enter R-SILENT). + +IDLE is the state where the VTU is provisioned through a management interface for the service desired by the operator. In this state, the VTU does not transmit any signal. A VTU that receives a higher layer signal to activate (c: L0\_request for VTU-O or r: L0\_request for VTU-R) shall use the initialization procedure defined in clause 12.3 to transition the link from the L3 to the L0 state. A VTU that detects the signals of the initialization procedure at the U reference point, if enabled, shall respond by using the initialization procedure. If disabled, the VTU shall remain in the IDLE state. + +The link transitions to the L0 state once the initialization procedure has completed successfully and both VTUs are in the SHOWTIME state. A VTU-O shall return to the O-SILENT state upon a guided power management (c: L3\_request, see clause 11.2.3.9), or upon a re-initialization triggered by Re-Initialization Policy (see clause 12.1.4). A VTU-R shall return to the R-SILENT state upon a guided power management (r: L3\_request, see clause 11.2.3.9), or upon a re-initialization triggered by Re-Initialization Policy (see clause 12.1.4). With the former, a VTU-R shall set AUTO\_init=OFF to disable autonomous proceeding to the R-INIT/HS state. With the latter, a VTU-R shall set AUTO\_init=ON to enable autonomous proceeding to the R-INIT/HS state. + +The receiving VTU shall transition from the SHOWTIME state upon Persistent LOS and/or LOF failure (see clause 12.1.4). This implies that if no high\_BER-hs or high\_BER-fs events cause the receiving VTU to transition state earlier, then the persistency of the LOS and/or LOF failure allows the transmitting VTU to detect the LOS or LOF failure condition through the indicator bits, before the receiving VTU transitions state. + +NOTE 2 – High\_BER-fs event relates to fast start-up, which is for further study (see clause 12.5). + +The receiving VTU shall also transition state upon a high\_BER event (see clause 12.1.4). This event relates to near-end and/or far-end performance primitives and performance counters for which thresholds may be configured through the CO-MIB as to declare a high\_BER event upon threshold crossing. + +A VTU-O shall either enter the O-SILENT state via the O-DEACTIVATING state, upon a guided power management (c: L3\_request), or upon a re-initialization triggered by Re-Initialization Policy. + +NOTE 3 – Setting the duration of O-DEACTIVATING (vendor discretionary) to zero implements an immediate transition from O-SHOWTIME to O-SILENT. + +When the VTU-O transitions from the O-SHOWTIME state to the O-DEACTIVATING state followed by transition to the O-SILENT state, the VTU-R detects a Persistent LOS Failure. Upon detection, the VTU-R shall transition to the R-SILENT state followed by the R-INIT/HS state and shall start transmitting R-TONES-REQ within a maximum of 6 s after the VTU-O transitioning to the O-SILENT state. + +When the VTU-O transitions from the O-INIT/TRAIN state to the O-DEACTIVATING state followed by transition to the O-SILENT state, , the VTU-R detects a failure in the training. Upon detecting a failure in the training, the FTU-R shall transition to the R-SILENT state followed by transition to the R-INIT/HS state. + +NOTE 4 – The direct transition from the O-INIT/TRAIN state to the O-SILENT state is shown in Figure 6-2 as a transition via the O-DEACTIVATING state, the duration of which is vendor discretionary and may be zero DMT symbols. + +When the VTU-R transitions from the R-SHOWTIME state to the R-SILENT state, the VTU-O detects a Persistent LOS Failure. Upon detection, the VTU-O shall transition to the O-DEACTIVATING state followed by transition to the O-SILENT state, either followed by waiting to receive R-TONES-REQ (VTU-R initiated HS) or followed by the O-INIT/HS state (VTU-O initiated HS). + +NOTE 5 – While the VTU-O is in the O-DEACTIVATING state, the VCE may update the FEXT cancellation coefficients among the showtime lines. + +![State diagram for the VTU-O showing states O-IDLE, O-SELFTEST, O-UNIT-FAIL, O-SILENT, O-INIT/HS, O-INIT/DIAG, O-INIT/TRAIN, O-SHOWTIME, and O-DEACTIVATING with various transitions between them.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +``` + +stateDiagram-v2 + [*] --> O-SELFTEST : Power on + O-SELFTEST --> O-IDLE : o:_selftest, Pass + O-SELFTEST --> O-UNIT-FAIL : Fail + O-UNIT-FAIL --> O-SELFTEST : o:_selftest + O-IDLE --> O-SILENT : o:_L0_request + O-IDLE --> [*] : o:_idle_ignore, Any state + O-SILENT --> O-INIT/HS : o:_L0_request or r-tones-req + O-SILENT --> O-INIT/DIAG : Pass with silent or no mode selected + O-INIT/HS --> O-INIT/TRAIN : Pass with mode selected + O-INIT/HS --> O-INIT/DIAG : Diagnostics + O-INIT/TRAIN --> O-SHOWTIME : Pass + O-INIT/TRAIN --> O-INIT/HS : Fail + O-SHOWTIME --> O-INIT/HS : r:_L3_request and o:_L3_reject, o:_L3_request and r:_L3_reject + O-SHOWTIME --> O-INIT/TRAIN : high_BER-fs + O-SHOWTIME --> O-DEACTIVATING : Re-initialization triggered by Re-initialization policy, r:_L3_request and o:_L3_grant, o:_L3_request and r:_L3_grant + O-DEACTIVATING --> O-SILENT : Re-initialization + O-DEACTIVATING --> O-INIT/HS : Fail + +``` + +Legend: + +- denotes a state +- c denotes a transition under condition c + +G.993.5(15)-Amd.1(16)\_F6-2 + +State diagram for the VTU-O showing states O-IDLE, O-SELFTEST, O-UNIT-FAIL, O-SILENT, O-INIT/HS, O-INIT/DIAG, O-INIT/TRAIN, O-SHOWTIME, and O-DEACTIVATING with various transitions between them. + +Figure 6-2 – State diagram for the VTU-O + +**Table 6-1 – VTU-O state definitions** + +| State name | Description | +|-----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| O-SELFTEST
(mandatory) |
  • Temporary state entered after power-up in which the VTU performs a self-test;
  • Transmitter off (QUIET at U-O interface);
  • Receiver off (no response to R-TONES-REQ signal);
  • No response to host control channel;
  • If self-test pass then transition to O-IDLE;
  • If self-test fail then transition to O-UNIT-FAIL.
| +| O-UNIT-FAIL
(mandatory) |
  • Steady state entered after an unsuccessful VTU self-test;
  • Transmitter off (QUIET at U-O interface);
  • Receiver off (no response to R-TONES-REQ signal);
  • Monitor host control channel if possible (allows the host controller to retrieve self-test results).
| +| O-IDLE
(mandatory) |
  • Steady state entered after successful self-test;
  • Transmitter off (QUIET at U-O interface);
  • Receiver off (no response to R-TONES-REQ signal);
  • Monitor host control channel.
| +| O-SILENT
(mandatory) |
  • Steady state defined in [ITU-T G.994.1], entered upon host controller command;
  • Transmitter off (QUIET at U-O interface);
  • Receiver on (monitor for R-TONES-REQ signal, if detected, transition to O-INIT/HS state);
  • Monitor host control channel.
| +| O-INIT/HS
(mandatory) |
  • Temporary state entered to perform ITU-T G.994.1 phase of initialization;
  • Transmitter on (start with transmitting C-TONES signal);
  • Receiver on (start with monitoring for R-SILENT0 signal);
  • Monitor host control channel;
  • If silent period or no mode selected then transition to O-SILENT1;
  • If loop diagnostics mode then transition to O-INIT/DIAG;
  • If operating mode selected then transition to O-INIT/TRAIN.
| +| O-INIT/TRAIN
(mandatory) |
  • Temporary state entered to perform other phases of initialization;
  • Transmitter on (start with O-P-QUIET1);
  • Receiver on (start with monitoring for R-P-QUIET1);
  • If init pass then transition to O-SHOWTIME;
  • If init fail then transition to O-DEACTIVATING;
  • Monitor host control channel.
| +| O-INIT/DIAG
(mandatory) |
  • Temporary state entered to perform other phases of initialization in loop diagnostics mode;
  • Transmitter on (start with O-P-QUIET1);
  • Receiver on (start with monitoring for R-P-QUIET1);
  • Transition to O-SILENT;
  • Monitor host control channel.
| + +**Table 6-1 – VTU-O state definitions** + +| State name | Description | +|-------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| O-SHOWTIME
(mandatory) |
  • Steady state in which one or more bearer channels are active;
  • On-line reconfigurations occur within this state;
  • Upon conditions satisfying the Re-Initialization Policy (RIpolicy_n) then transition to O-DEACTIVATING;
  • If link transition to L3 state is granted, then transition to O-DEACTIVATING;
  • Monitor host control channel.
| +| O-DEACTIVATING
(mandatory) |
  • Temporary state entered upon line transition to L3 state. The duration of this state is vendor discretionary and may be zero;
  • Transmitter is on: VTU-O shall not transmit the direct signal (i.e, Z_i=0 for all sub-carriers) while it may transmit the pre-compensation signal Z_i' in downstream;
  • Receiver may be on: VTU-O may receive signals in upstream to support upstream FEXT cancellation;
  • VCE may update the downstream and upstream FEXT cancellation coefficients;
  • Controlled by the VCE, the VTU-O transitions to the O-SILENT state.
| + +## 6.3 Upstream vectoring requirements for the VTU-O + +The implementation at the CO-side is vendor discretionary, apart from the required ability to convey sync symbol timing and upstream vectoring control parameters from the VCE to the end of the line nearer to the customer premises (CP-side). These requirements are defined in clause 10 and apply to each VTU-O member of a vectored group. + +The VTU-O shall comply with [ITU-T G.993.2], with the exceptions and additional requirements contained in this Recommendation. + +During initialization, each VTU-O in a vectored group shall have the capability to transmit a time marker to the VTU-R to indicate which symbols are at a time position that coincides with Showtime sync symbols on active lines. The modulation method of such time marker on such symbols is defined in clause 10.3.3.5. + +The VTU-O shall have the capability to convey the control parameters of the upstream vectored group defined in clause 7 and clause 10 from the VCE to the CP-side. + +If upstream vectoring is enabled, the VTU-O shall support operation also in the case when not all probe tones of the upstream sync symbol have the same sign, but the sign pattern over the tones of the sync symbol has a periodicity of 10 tones (considering both probe and flag tones). + +## 6.4 Requirements for the VCE + +The VCE shall support downstream vectoring. + +The VCE shall include the capability to be controlled by the ME over the $\epsilon$ -m interface (shown in Figure 5-1) to use $B\_min=0$ (see Table 7-1 for the definition and Table 7-2 for valid values of $B\_min$ ). + +# 7 CP-side requirements in a vectored group + +This clause describes the CP-side steady-state behaviour as part of an N-pair vectored group. + +## 7.1 General + +The VTU-R shall send clipped error samples (defined in clause 7.2.1) to the VCE of the vectored group, through the backchannel (defined in clauses 7.2.2 through 7.2.4). The VTU-R shall support Layer 2 Ethernet encapsulation (defined in clause 7.4.1) and shall support embedded operation channel (eoc) encapsulation (defined in clause 7.4.2) of the backchannel information. The VCE shall select the encapsulation method to be used, and communicate this setting to the VTU-R during initialization (see clause 10.5.2.1). The set encapsulation method shall be kept unchanged during Showtime. + +Figure 7-1 shows the reference model for the Layer 2 encapsulated backchannel information flow. Within the NT, the clipped error samples are first sent from the VTU-R to the L2+ functional block (*streamBC.indicate* primitive), where they are encapsulated into the Layer 2 transport protocol (defined in clause 7.4.1) and further multiplexed into one of the upstream Ethernet (or Ethernet over ATM) data streams (*stream(n).confirm*, see Annex K of [ITU-T G.993.2]). At the AN, the Layer 2 encapsulation is terminated in the L2+ functional block and the clipped error samples are delivered to the VCE (*streamBC.indicate* primitive). + +![Figure 7-1: Reference model for the Layer 2 encapsulated backchannel information flow. The diagram shows the flow of data between an Access Network (AN) and a Network Termination (NT) unit. In the AN, the VTU-O receives downstream streams and sends upstream streams. The VCE sends backchannel information (StreamBC.indicate, StreamBC.request, StreamBC.confirm) to the VTU-O. The VTU-O encapsulates this information into an 'eoc' message and sends it to the VTU-R in the NT. In the NT, the VTU-R receives the 'eoc' message and sends it to the VME. The VME encapsulates the information into a Layer 2 transport protocol (L2enc) and sends it to the L2+ functional block. The L2+ functional block then sends the information to the VTU-R, which sends it to the VCE. The VCE then sends the information to the AN via the VTU-O. The diagram also shows the flow of downstream and upstream streams between the AN and the NT, and the internal components of the AN and NT.](eb03559a4d92ea9ebd63ea9be663c50a_img.jpg) + +The diagram illustrates the reference model for the Layer 2 encapsulated backchannel information flow. It is divided into two main sections: AN (Access Network) on the left and NT (Network Termination) on the right, connected by a dashed line representing the U-C (User-C) and U-R (User-R) interfaces. In the AN, the VTU-O (VDSL2 Transceiver) receives 'Downstream stream(n).confirm' and sends 'Upstream stream(n).indicate'. The VCE (Vectored Control Entity) sends 'StreamBC.indicate', 'StreamBC.request', and 'StreamBC.confirm' to the VTU-O. The VTU-O encapsulates these into an 'eoc' message and sends it to the VTU-R in the NT. In the NT, the VTU-R receives the 'eoc' message and sends it to the VME (VDSL2 Management Entity). The VME encapsulates the information into a Layer 2 transport protocol (L2enc) and sends it to the L2+ functional block. The L2+ functional block then sends the information to the VTU-R, which sends it to the VCE. The VCE then sends the information to the AN via the VTU-O. The diagram also shows the flow of downstream and upstream streams between the AN and the NT, and the internal components of the AN and NT, including L2dec and L2+ functional blocks. + +Figure 7-1: Reference model for the Layer 2 encapsulated backchannel information flow. The diagram shows the flow of data between an Access Network (AN) and a Network Termination (NT) unit. In the AN, the VTU-O receives downstream streams and sends upstream streams. The VCE sends backchannel information (StreamBC.indicate, StreamBC.request, StreamBC.confirm) to the VTU-O. The VTU-O encapsulates this information into an 'eoc' message and sends it to the VTU-R in the NT. In the NT, the VTU-R receives the 'eoc' message and sends it to the VME. The VME encapsulates the information into a Layer 2 transport protocol (L2enc) and sends it to the L2+ functional block. The L2+ functional block then sends the information to the VTU-R, which sends it to the VCE. The VCE then sends the information to the AN via the VTU-O. The diagram also shows the flow of downstream and upstream streams between the AN and the NT, and the internal components of the AN and NT. + +**Figure 7-1 – Reference model for the Layer 2 encapsulated backchannel information flow** + +Figure 7-2 shows the reference model for the eoc encapsulated backchannel information flow. Within the VTU-R, the clipped error samples are sent to the VDSL2 management entity (VME), where they are encapsulated into an eoc message, as defined in clause 8.1. At the VDSL2 management entity (VME, see clause 11.2 of [ITU-T G.993.2]) of the VTU-O, the eoc encapsulation is terminated and the clipped error samples are delivered to the VCE (*streamBC.indicate* primitive). + +![Figure 7-2: Reference model for the eoc encapsulated backchannel information flow. The diagram shows two main entities, AN (left) and NT (right), connected by a dashed line representing the U-C (Upstream Control) and U-R (Upstream Rate) interface points. AN contains an L2+ block, a VTU-O block, a VME block, and a VCE block. NT contains an L2+ block, a VTU-R block, and a VME block. Data flow includes: Downstream stream(n).confirm from L2+ to VTU-O; Upstream stream(n).indicate from VTU-O to L2+; Stream(n) from VTU-O to VTU-R; Stream(n) from VTU-R to VTU-O; eoc from VTU-R VME to VTU-O VME; StreamBC.indicate, StreamBC.request, and StreamBC.confirm from VCE to VME in AN; and StreamBC.confirm from VME to VCE in AN. A label 'ε-c' is present near the L2+ block in AN. A label 'G.993.5(15)_F7-2' is present in the bottom right corner of the diagram area.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg) + +Figure 7-2: Reference model for the eoc encapsulated backchannel information flow. The diagram shows two main entities, AN (left) and NT (right), connected by a dashed line representing the U-C (Upstream Control) and U-R (Upstream Rate) interface points. AN contains an L2+ block, a VTU-O block, a VME block, and a VCE block. NT contains an L2+ block, a VTU-R block, and a VME block. Data flow includes: Downstream stream(n).confirm from L2+ to VTU-O; Upstream stream(n).indicate from VTU-O to L2+; Stream(n) from VTU-O to VTU-R; Stream(n) from VTU-R to VTU-O; eoc from VTU-R VME to VTU-O VME; StreamBC.indicate, StreamBC.request, and StreamBC.confirm from VCE to VME in AN; and StreamBC.confirm from VME to VCE in AN. A label 'ε-c' is present near the L2+ block in AN. A label 'G.993.5(15)\_F7-2' is present in the bottom right corner of the diagram area. + +**Figure 7-2 – Reference model for the eoc encapsulated backchannel information flow** + +Regardless of the backchannel encapsulation method, the VCE communicates with the VTU-O VME to set the backchannel control parameters (defined in Table 7-1), e.g., for which subcarriers the VTU-R shall send clipped error samples through the backchannel (streamBC.request primitive). The VTU-O VME uses eoc commands (defined in clause 8.1) to communicate these backchannel control parameters to the VTU-R VME and delivers the information received from VTU-R VME eoc responses back to the VCE (streamBC.confirm primitive). + +The VTU-R shall support seamless rate adaptation (SRA, OLR Type 3) in the downstream and upstream direction, including mandatory support within SRA of: + +- dynamic interleaver reconfiguration (change of $D_p$ ); +- framing reconfiguration (change of $T_p$ , $G_p$ and $B_{p0}$ ). + +as defined in clause 13.1 of [ITU-T G.993.2], titled "Types of on-line reconfiguration". + +If [ITU-T G.998.4] is enabled in a particular direction, the VTU-R shall also support seamless rate adaptation (SRA, OLR Type 5) in this same direction, including mandatory support within SRA of all configurations specified in clause C.3.2 of [ITU-T G.998.4]. + +## 7.2 Downstream vectoring requirements for the VTU-R + +The VTU-R shall comply with [ITU-T G.993.2], with the exceptions and additional requirements contained in this Recommendation. + +This Recommendation defines that all probe tones of a sync symbol, both during initialization and during Showtime, may have the same sign (i.e., if a frequency independent pilot sequence is modulated, see clause 6.2.3) or may not have the same sign (i.e., if frequency dependent pilot sequence is modulated, see clause 6.2.3). The VTU-R shall support reception and all related functionalities required for computing error signals also in case when not all probe tones of the sync symbol have the same sign, but the sign pattern over the tones of the downstream sync symbol has a periodicity of 10 tones (considering both probe and flag tones). + +### 7.2.1 Definition of normalized error sample + +The VTU-R converts the received time domain signal into frequency domain samples, resulting in a complex value $Z$ for each of the received subcarriers. The subsequent constellation de-mapper associates each of these complex values $Z$ with a constellation point, represented by a value $\hat{C}$ . Figure 7-3 shows the computation of a normalized error sample $E$ for a particular subcarrier in a + +particular sync symbol. The normalized error sample represents the error between the received complex data sample $Z$ normalized to the 4-quadrature amplitude modulation (QAM) constellation point and the corresponding decision constellation point $\hat{C}$ associated with the received sync symbol in a VTU-R and referred to the input of the constellation descrambler. For illustration, in Figure 7-3, the received normalized complex data sample $Z$ is shown to occur within the constellation boundary of the decision constellation point $\hat{C} = (+1, +1)$ . + +For each of the subcarriers, the complex normalized error sample $E$ is defined as $E = Z - \hat{C}$ , where $E$ is the complex error defined as $E = e_x + j \times e_y$ with real component $e_x$ and imaginary component $e_y$ , and $Z$ is the received normalized data sample defined as $Z = z_x + j \times z_y$ with real component $z_x$ and imaginary component $z_y$ , and $\hat{C}$ is the decision constellation point associated with the received data sample $Z$ , defined as $\hat{C} = \hat{c}_x + j \times \hat{c}_y$ with real component $\hat{c}_x$ and imaginary component $\hat{c}_y$ (with $\hat{c}_x = \pm 1$ and $\hat{c}_y = \pm 1$ ). + +![Figure 7-3: Definition of the normalized error sample E. The diagram shows a 2D coordinate system with X and Y axes. A point C-hat is marked at (1, 1) and labeled 'Constellation expected point (referred to the input of the constellation descrambler)'. A point Z is marked at (z_x, z_y) and labeled 'Received complex normalized sample'. A vector E is drawn from C-hat to Z, labeled 'Complex normalized error sample'. The horizontal component of E is labeled 'Real error component e_x' and the vertical component is labeled 'Imaginary error component e_y'. The diagram also shows 'Constellation boundary' lines at X=1 and Y=1. The source G.993.5(15)_F7-3 is noted at the bottom right.](5500ab73cf84ccc0055eecf28889b4db_img.jpg) + +Figure 7-3: Definition of the normalized error sample E. The diagram shows a 2D coordinate system with X and Y axes. A point C-hat is marked at (1, 1) and labeled 'Constellation expected point (referred to the input of the constellation descrambler)'. A point Z is marked at (z\_x, z\_y) and labeled 'Received complex normalized sample'. A vector E is drawn from C-hat to Z, labeled 'Complex normalized error sample'. The horizontal component of E is labeled 'Real error component e\_x' and the vertical component is labeled 'Imaginary error component e\_y'. The diagram also shows 'Constellation boundary' lines at X=1 and Y=1. The source G.993.5(15)\_F7-3 is noted at the bottom right. + +**Figure 7-3 – Definition of the normalized error sample $E$** + +The real and imaginary components of each normalized error sample $E$ are clipped and quantized to integer values for the clipped error sample components $q_x$ and $q_y$ respectively, as follows: + +$$\begin{aligned} q_x &= \max\left(-2^{B_{\max}}, \min\left(\left\lfloor e_x \times 2^{N_{\max}-1} \right\rfloor, 2^{B_{\max}} - 1\right)\right) \\ q_y &= \max\left(-2^{B_{\max}}, \min\left(\left\lfloor e_y \times 2^{N_{\max}-1} \right\rfloor, 2^{B_{\max}} - 1\right)\right) \end{aligned}$$ + +where $Q = q_x + j \times q_y$ represents the clipped error sample and $N_{\max}$ represents the VTU-R's maximum quantization depth of normalized error samples and shall be set to 12, and $B_{\max}$ represents the upper bound of the bit index for reporting clipped error sample components $q_x$ and $q_y$ ( $B_{\max} < N_{\max}$ , with $B_{\max}$ configured by the VCE, see Tables 7-1 and 7-2). + +The values of both clipped error sample components $q_x$ and $q_y$ shall be represented using the two's-complement representation of $B_{\max}+1$ bits. The format of the clipped error sample for reporting over the backchannel is defined in clause 7.2.2. The particular subcarriers on which + +clipped error samples shall be reported during initialization and Showtime shall be configured as described in clauses 10.4.2.1, and in clause 8.1, respectively. + +### 7.2.2 Reporting of clipped error samples + +The VTU-R shall send clipped error samples (defined in clause 7.2.1) to the VTU-O through the backchannel established between the VTU-O and the VTU-R in each line of the vectored group, as defined in clause 7.4.1 (Layer 2 backchannel) or in clause 8.1 (eoc backchannel) or in clause 10 (special operations channel (SOC) backchannel). The VTU-O conveys the received clipped error samples to the VCE of the vectored group. + +#### 7.2.2.1 Control parameters for clipped error sample reporting + +The VCE communicates to the VTU-O a set of control parameters for clipped error sample reporting defined in Table 7-1. + +**Table 7-1 – Control parameters of clipped error samples** + +| Parameter name | Definition | +|-----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Vectored bands |

The downstream frequency bands for which the VTU-R shall send clipped error samples for the subcarriers through the backchannel.

The vectored downstream bands shall be defined by indices of the lowest frequency and the highest frequency subcarriers.

N\_band denotes the number of vectored bands configured. No more than eight bands shall be configured (i.e., N\_band \leq 8). The configured bands shall be identified by their numbers: vb = 0, 1, 2, 3, 4, 5, 6, 7 assigned in the ascending order of subcarrier indices associated with the band.

N\_carrier(vb) denotes the number of subcarriers in frequency band number vb, i.e., the index of the last subcarrier minus the index of the first subcarrier plus one.

The index of the first (lowest frequency) subcarrier of each vectored downstream band shall be an even value.

Each of the vectored downstream bands shall be assigned within the boundaries of a single ITU-T G.993.2 standard downstream band (as exchanged during the ITU-T G.994.1 phase) and possibly having more than one vectored band per such standard downstream band. The vectored bands shall not overlap one another.

| +| F_sub |

The sub-sampling factor to be applied to the vectored bands.

For every vectored downstream band, the clipped error sample of the subcarrier with the smallest index shall be transmitted first, followed by the clipped error sample of every F\_sub^{th} subcarrier within the vectored band.

Configured by the VCE for each vectored downstream band separately.

| +| F_block |

The block size (number of subcarriers) for grouping of clipped error samples.

Configured by the VCE. The same block size configuration shall be used for all vectored downstream bands (see Table 8-4).

| +| B_min |

Lower bound of the bit index for reporting of a clipped error sample component (see clause 7.2.2.2).

Configured by the VCE for each vectored downstream band separately.

| +| B_max |

Upper bound of the bit index for reporting of a clipped error sample component (see clause 7.2.1).

Configured by the VCE for each vectored downstream band separately.

| + +**Table 7-1 – Control parameters of clipped error samples** + +| Parameter name | Definition | +|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $L\_w$ | Maximum number of bits for reporting of a clipped error sample component.
Configured by the VCE for each vectored downstream band separately.
If $L\_w$ is set to 0 for a particular vectored downstream band, then that band shall not be reported. $L\_w$ shall be set to a non-zero value for at least one vectored downstream band. | +| padding | Indicates whether or not the VTU-R shall pad clipped error samples through sign extension or zero padding to maintain using $L\_w$ bits for reporting of a clipped error sample component if $S < L\_w - 1$ (see clause 7.2.2.2).
Configured by the VCE. The same padding configuration shall be used in all vectored downstream bands.
If padding is enabled, then $B\_min$ shall be set to 0. | + +Table 7-2 defines the optional and mandatory values for the clipped error samples control parameters. In particular, it defines the valid values for the VCE to configure and the mandatory values for the VTU-R to support. The VTU-O shall support all valid values for VCE to configure. The VTU-R shall indicate during initialization its capabilities to support optional values, and the VCE shall select the values accordingly (see clause 10). + +**Table 7-2 – Values of backchannel control parameters** + +| Parameter | Valid values for VCE | Mandatory values for VTU-R to support | +|----------------|---------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------| +| $F\_sub$ | 1, 2, 4, 8, 16, 32 and 64 | 2, 4, 8, 16, 32 and 64 | +| $F\_block$ | 1, 32, and $\left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$ | 1 and $\left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$ | +| $B\_min$ | 0, ... , 11 | All valid values | +| $B\_max$ | $B\_min$ , ... , 11 | All valid values | +| $L\_w$ | 0, 1, ... , $\min(8, B\_max - B\_min + 1)$ | 0, 1, ... , 8 | +| padding | 1 (enable);
0 (disable) with $F\_block = 32$ ;
0 (disable) with $F\_block = \left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$ | 1 (enable);
0 (disable) with $F\_block = \left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$ | + +For each vectored downstream band assigned by the VTU-O for clipped error sample reporting, the VTU-R shall report the clipped error samples for all subcarriers with indices $X = X\_L + n \times F\_sub$ , where $n$ gets all integer values 0, 1, 2, ... for which $X\_L \leq X \leq X\_H$ and with $X\_L$ and $X\_H$ respectively, the indices of the lowest frequency and the highest frequency subcarriers of the vectored downstream band. Clipped error samples of other subcarriers shall not be reported. + +On the subcarriers that are not used for transmission ( $b_i = 0$ , and $g_i = 0$ ) but assigned for clipped error sample reporting, the VTU-R shall report a dummy error sample. The value of this dummy error sample is vendor discretionary, but shall comply with error sample control parameters and shall not impact reports on other subcarriers. + +NOTE – It is the responsibility of the VTU-O and/or the VCE to identify and drop clipped error samples for subcarriers that are not intended for channel estimation. + +#### 7.2.2.2 Grouping of clipped error samples + +The VTU-R shall group clipped error samples into blocks. Valid block sizes for the parameter $F\_block$ are defined in Table 7-2. For each block, the VTU-R shall calculate parameters $B\_M$ and $B\_L$ . The parameters $B\_M$ and $B\_L$ represent the highest and the lowest bit indices of the reported clipped error sample, with the assumption that bit index is counted from the LSB to the MSB, starting from 0. + +Figure 7-4 depicts the example of $F\_block=1$ , $B\_min=2$ , $B\_max=10$ , $L\_w=4$ , and $padding=0$ . Two registers each ( $B\_max+L\_w$ ) bits wide contain a clipped error sample component in the bits labelled from $B\_max$ (clipped error sample MSB) down to 0 (clipped error sample LSB), while the $L\_w - 1 = 3$ remaining bits of each register are set to 0 and labelled with a negative bit index $-1$ down to $1 - L\_w = -3$ . For each component in the block, only the $B\_M - B\_L + 1$ bits with indices from $B\_M$ down to $B\_L$ inclusive are included in the error report block (ERB) format defined in clause 7.2.3.1. Parameters $B\_M$ and $B\_L$ shall be computed for each block as described below. The VTU-R shall examine all clipped error sample components in each block and determine for each component $ec$ ( $ec = 1$ to $2 \times F\_block$ ) a data-dependent scale parameter $s_{ec}$ , defined to be the sign bit index of the shortest 2's complement representation of the component. + +For example, as depicted in Figure 7-4, the first clipped error sample component, having the 11-bit 2's complement representation 11110010101, has shortest representation 10010101 and hence its scale is $s_1 = 7$ . Likewise, the second component 00000010010 has shortest representation 010010 and hence its scale is $s_2 = 5$ . + +The VTU-R then computes for each block a data-dependent block scale parameter $S = \max_{ec}(s_{ec})$ , where the maximization index $ec$ runs over all $2 \times F\_block$ clipped error sample components in the block. + +For example, as depicted in Figure 7-4, $F\_block = 1$ and the block scale parameter $S$ is the maximum of $s_1$ and $s_2$ , hence $S = 7$ . + +If $padding = 0$ , then for each block in the given vectored band, the VTU-R shall set + +$$B\_M = \max(S, B\_min), \quad B\_L = \max(B\_M - L\_w + 1, B\_min) \quad (7-1)$$ + +If $padding = 1$ , then for each block in all the vectored bands, the VTU-R shall set either $B\_M = \max(S, L\_w - 1)$ (sign extension) or $B\_M = S$ (zero padding); and + +$$B\_L = B\_M - L\_w + 1 \text{ (with bits set to 0 for bit indices } < 0\text{).} \quad (7-2)$$ + +The parameters $B\_M$ and $B\_L$ shall always satisfy the relations $B\_L \leq B\_M$ and $0 \leq B\_M \leq B\_max$ . + +![Diagram illustrating two registers representing clipped error sample components. The top register shows bits from MSB (B_max=10) to LSB (0), with negative bit indices -1 to -3. The bottom register shows bits from B_M to B_L, with L_w=4. Arrows indicate the scale parameters s1=7 and s2=5, and the block scale parameter S.](68ea9310fb829dd6007635a6cd4ea2ad_img.jpg) + +The diagram shows two horizontal registers, each 14 bits wide. The top register contains the bit sequence: 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0. Above the first bit (index 10) is the label 'MSB' and 'B\_max = 10'. Above the remaining bits are labels: 3, 2, 1, 0, -1, -2, -3, with 'LSB' above the 0. Below the 4th bit (index 7) is an arrow labeled 's1 = 7'. Below the 6th bit (index 5) is an arrow labeled 's2 = 5'. The bottom register contains the bit sequence: 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0. Above the 7th bit (index 2) is an arrow labeled 'B\_min = 2'. Above the 10th bit (index 5) is an arrow labeled 'B\_L'. Above the 14th bit (index 10) is an arrow labeled 'B\_M'. A bracket between the 10th and 6th bits is labeled 'L\_w = 4'. A bracket between the 14th and 7th bits is labeled 'S'. + +Diagram illustrating two registers representing clipped error sample components. The top register shows bits from MSB (B\_max=10) to LSB (0), with negative bit indices -1 to -3. The bottom register shows bits from B\_M to B\_L, with L\_w=4. Arrows indicate the scale parameters s1=7 and s2=5, and the block scale parameter S. + +G.993.5(15)\_F7-4 + +Figure 7-4 – Example of two registers, each representing a clipped error sample component + +Figure 7-5 depicts an example of the reported bits (shown shaded) for a block of clipped error samples for different padding types, with $F\_block=1$ , $B\_min=1$ , $B\_max=7$ , $L\_w=5$ . + +![Figure 7-5: Example of reported bits for a block of clipped error samples for different padding types. The diagram shows three examples of 8-bit blocks. Each block has a Most Significant Bit (MSB) at position 7 and a Least Significant Bit (LSB) at position 0. The first example shows a block with 5 bits (positions 3 to 0) shaded, with B_M=S=3, B_L=1, L_w=5, B_min=1, padding=0. The second example shows a block with 6 bits (positions 3 to 0) shaded, with B_M=4, S=3, B_L=0, L_w=5, B_min=1, padding=1 with sign-extension. The third example shows a block with 7 bits (positions 3 to 0) shaded, with B_M=S=3, B_L=-1, L_w=5, B_min=1, padding=1 with zero-padding. The shaded bits represent the reported bits for the block.](2bacc162a73d75c43a7f90715832bd13_img.jpg) + +MSB $B\_max = 7$      3   2   1   0      LSB + +| | | | | | | | | +|---|---|---|---|---|---|---|---| +| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | +| 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | + + $B\_M = S = 3$   $B\_L = 1$ + $L\_w = 5, B\_min = 1$ +padding = 0 + +MSB $B\_max = 7$      3   2   1   0      LSB + +| | | | | | | | | +|---|---|---|---|---|---|---|---| +| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | +| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | + + $B\_M = 4$   $S = 3$   $B\_L = 0$ + $L\_w = 5, B\_min = 1$ +padding = 1 with sign-extension + +MSB $B\_max = 7$      3   2   1   0   -1      LSB + +| | | | | | | | | +|---|---|---|---|---|---|---|---| +| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | +| 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | + + $B\_M = S = 3$   $B\_L = -1$ + $L\_w = 5, B\_min = 1$ +padding = 1 with zero-padding + +G.996.5(15)\_F7-5 + +Figure 7-5: Example of reported bits for a block of clipped error samples for different padding types. The diagram shows three examples of 8-bit blocks. Each block has a Most Significant Bit (MSB) at position 7 and a Least Significant Bit (LSB) at position 0. The first example shows a block with 5 bits (positions 3 to 0) shaded, with B\_M=S=3, B\_L=1, L\_w=5, B\_min=1, padding=0. The second example shows a block with 6 bits (positions 3 to 0) shaded, with B\_M=4, S=3, B\_L=0, L\_w=5, B\_min=1, padding=1 with sign-extension. The third example shows a block with 7 bits (positions 3 to 0) shaded, with B\_M=S=3, B\_L=-1, L\_w=5, B\_min=1, padding=1 with zero-padding. The shaded bits represent the reported bits for the block. + +**Figure 7-5 – Example of reported bits for a block of clipped error samples for different padding types** + +For the assigned value of $F\_block$ , the block consists of clipped error samples reported for $F\_block$ subsequent subcarriers from those assigned for reporting in the vectored downstream band. The subcarriers shall be assigned to blocks starting from the lowest frequency subcarrier of the vectored band, subsequently, in ascending order, $F\_block$ subcarriers in each block. The number of blocks in the vectored band $vb$ can be computed as: + +$$N\_block(vb) = \left\lceil \frac{\left\lceil \frac{N\_carrier(vb)}{F\_sub(vb)} \right\rceil}{F\_block} \right\rceil$$ + +The blocks shall be identified by their numbers: $eb = 0$ to $N\_block(vb) - 1$ , assigned in the ascending order of subcarrier indices associated with the block. The last components of the last block that do not belong to the subcarriers of the vectored downstream band (if any) shall be set to dummy values that represent the value of zero. + +### 7.2.3 Backchannel format + +For each sync symbol, an integer number of octets shall be sent through the backchannel. + +The number of bytes per symbol needed to report the clipped error samples depends on the values configured by the VCE for the backchannel control parameters (see clause 7.2.2). Blocks of clipped error samples (error blocks) of the vectored downstream bands are mapped into the ERB. + +Each ERB is associated with a particular symbol of the O-P-VECTOR 2-1 signal (see clause 10.4.3.7). The ERB has a single format that is further encapsulated into: + +- Ethernet format (for an L2-based backchannel); or +- eoc format (for an eoc-based backchannel); or +- SOC format (for an SOC-based backchannel). + +The sync symbol associated with the ERB is identified by the value of its sync symbol counter (for an L2 or an eoc backchannel during Showtime) or by the timing of the report (for an SOC backchannel during initialization). + +#### 7.2.3.1 Format of the ERB + +The format of the ERB is presented in Figure 7-6. The ERB starts from an 8-bit ERB\_ID field, followed by up to eight vectored band blocks (VBBs) fields. The VTU-R may set the MSB of the + +ERB\_ID field to '1' to indicate that the clipped error samples in the ERB are potentially corrupted (e.g., due to impulse noise, or RFI). Otherwise, the VTU-R shall set the MSB of the ERB\_ID field to '0'. The seven LSB of the ERB\_ID field shall be set to 0 and are reserved for ITU-T. The number of bytes in the ERB ( $N\_ERB$ ) is the sum of the number of bytes in each of the VBBs, plus one byte for the ERB\_ID field. The concatenation of VBBs in an ERB shall be in the ascending order of the vectored band numbers, i.e., starting from the vectored band associated with lowest subcarrier indices. Some vectored bands may not be reported on request of the VCE (i.e., the ERB shall not contain a VBB for the vectored bands for which VCE configures $L\_w=0$ ). + +![Figure 7-6: ERB format diagram showing ERB_ID (1 byte), VBB-1 (N_VBB(1) bytes), and VBB-3 (N_VBB(3) bytes). The total ERB consists of N_ERB bytes. Source: G.993.5(15)_F7-6](5414f65867392f05ba0063b208eeb5e1_img.jpg) + +| | | | +|--------------------------------|-------------------|-------------------| +| ERB_ID | VBB-1 | VBB-3 | +| 1 byte | $N\_VBB(1)$ bytes | $N\_VBB(3)$ bytes | +| ERB consists of $N\_ERB$ bytes | | | + +G.993.5(15)\_F7-6 + +Figure 7-6: ERB format diagram showing ERB\_ID (1 byte), VBB-1 (N\_VBB(1) bytes), and VBB-3 (N\_VBB(3) bytes). The total ERB consists of N\_ERB bytes. Source: G.993.5(15)\_F7-6 + +Figure 7-6 – ERB format (in case only vectored bands 1 and 3 are requested by the VCE) + +The format of the VBB is presented in Figure 7-7. Each VBB starts from an 8-bit VBB\_ID field, followed by a VBB\_Aux field, followed by concatenated error blocks, and ends with a pad of 0, 2, 4 or 6 bits to fit the length of the VBB to an integer number of bytes (odd number of padding bits is not applicable). The three MSBs of the VBB\_ID field shall include the number of the vectored band (000 for VBB-0, 001 for VBB-1, ... up to 111 for VBB-7). The five LSBs of the VBB\_ID field shall be set to '0' and be reserved for ITU-T. The error blocks shall be concatenated in a VBB in ascending order: the first block inside the vectored band is the one that contains clipped error samples for subcarriers with lowest indices and shall be transmitted first. + +![](744acfe8d4e31bcf03f95714c2f6e567_img.jpg) + +$F\_block = \lceil N\_carried/F\_sub \rceil$ + +| | | | | | +|---------------------------------------------------------------------------------------|---------|--------|-------------------------------------------|--------------------| +| VBB_ID | VBB_Aux | B_M | $F\_block$ error samples in error block 0 | Pad | +| 8 bits | 12 bits | 4 bits | | 0, 2, 4, or 6 bits | +| Error block 0 | | | | | +| (24 + $F\_block(vb) \times 2 \times (B\_M(vb) - B\_L(vb) + 1)$ ) bits without padding | | | | | +| (24 + $F\_block(vb) \times 2 \times L\_w(vb)$ ) bits with padding | | | | | + +$F\_block = 32$ + +| | | | | | | | | | +|------------------------------------------------------------------------------------------------|---------|--------|-----------------------------------|----------|---------------|-----------------------------------|-----|--------------------| +| VBB_ID | VBB_Aux | B_M | 32 error samples in error block 0 | Block ID | B_M | 32 error samples in error block 1 | ... | Pad | +| 8 bits | 12 bits | 4 bits | | 4 bits | 4 bits | | | 0, 2, 4, or 6 bits | +| Error block 0 | | | | | Error block 1 | | | | +| (16 + $\sum (8 + 32 \times 2 \times (B\_M(vb, eb) - B\_L(vb, eb) + 1))$ ) bits without padding | | | | | | | | | +| (16 + $N\_block(vb) \times (8 + 32 \times 2 \times L\_w)$ ) bits with padding | | | | | | | | | + +$F\_block = 1$ + +| | | | | | | | | | +|---------------------------------------------------|--------|---------------------------------|---------------|---------------------------------|--------|---------------------------------|-----|--------------------| +| VBB_ID | B_M | 1 error sample in error block 0 | B_M | 1 error sample in error block 1 | B_M | 1 error sample in error block 2 | ... | Pad | +| 8 bits | 4 bits | | 4 bits | | 4 bits | | | 0, 2, 4, or 6 bits | +| Error block 0 | | | Error block 1 | | | Error block 2 | | | +| (8 + $N\_block \times (4 + 2 \times L\_w)$ ) bits | | | | | | | | | +| Padding is mandatory with $F\_block = 1$ | | | | | | | | | + +G.993.5(15)\_F7-7 + +Figure 7-7 – VBB format depending on $F\_block$ + +The format of the error block is defined in clause 7.2.3.2. + +In case $F\_block = 32$ , a Block\_ID shall be pre-pended to each error block, starting with error block number 1. A Block\_ID shall not be inserted just before error block 0. The Block\_ID shall be 4 bits long, and shall represent modulo 16 the number of the error block it precedes as an unsigned integer, with the assumption that the first block in the vectored band has the number 0. + +In case $F\_block = 1$ or $\left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$ , a Block\_ID shall not be inserted. + +NOTE 1 – The VCE can identify VBB in the received ERB by its VBB\_ID and then compute the number of error blocks, $N\_block(vb)$ , in the VBB-vb as described in clause 7.2.2.2, since all the backchannel control parameters are known at the CO-side. The length of the error block is computed using the parameters ( $B\_M$ , $B\_L$ ) of the clipped error sample and the block size $F\_block$ . The first reported sample of the first error block in the vectored band is for the subcarrier with index $X\_L$ (which is always even). + +NOTE 2 – With $F\_block = 32$ , the end of each error block is byte aligned. No padding bits are added at the end of the VBB. + +The VBB\_Aux field shall be used to communicate the mean error value using the format defined in Table 7-3. The mean error ( $ME$ ) for vectored band $vb$ shall be computed as: + +$$ME(vb) = \left\lceil \frac{N\_carrier(vb)}{F\_sub(vb)} \right\rceil_{-1} \sum_{n=0} (|e\_x(X\_L(vb) + n \times F\_sub(vb))| + |e\_y(X\_L(vb) + n \times F\_sub(vb))|)$$ + +where $e\_x(sc)$ and $e\_y(sc)$ are real and imaginary components of the normalized error estimated on subcarrier $sc$ (see Figure 7-3). + +The clipped and quantized value of $ME(vb)$ shall be represented as: + +$$MEq(vb) = \min \left( \left\lfloor ME(vb) \times 2^{ME\_N\_max-1} \right\rfloor, 2^{ME\_B\_max} - 1 \right)$$ + +where $ME\_N\_max = 12$ and $ME\_B\_max = 22$ . + +The value of the $MEq$ shall be reported using a 4-bit exponent and an 8-bit mantissa, in the similar way as for the clipped error sample components. The VTU-R shall compute the scale $ME\_S$ as the index of the most significant bit of the $MEq$ that is not a sign extension bit. The mantissa shall consist of the 8 bits with indices $ME\_B\_M$ down to $ME\_B\_L$ . The values of $ME\_B\_M$ and $ME\_B\_L$ shall be computed at the VTU-R as: + +$$ME\_B\_M = \max(ME\_S, 7), \text{ and}$$ + +$$ME\_B\_L = ME\_B\_M - 7$$ + +**Table 7-3 – Format of the VBB\_Aux field** + +| Parameter | Bit numbers | Description | +|------------|-------------|-----------------------------| +| $ME\_EXP$ | [11:8] | 4-bit value of $ME\_B\_L$ | +| $ME\_MANT$ | [7:0] | 8-bit mantissa of the $MEq$ | + +#### 7.2.3.2 Format of the error block + +The representation for an error block containing $F\_block$ clipped error samples ( $2 \times F\_block$ clipped error sample components of $F\_block$ subcarriers) shall include a $B\_M$ field (4 bits), and an error field (variable length), see Figure 7-8. The error field includes $F\_block$ sub-fields, each carrying a complex clipped error sample of a subcarrier which is assigned for reporting during the backchannel configuration (see clause 7.2.2). + +For each clipped error sample component, the compressed representation, as defined in clause 7.2.2.2, includes only those bits of the clipped error sample component with indices $B\_L$ through $B\_M$ , using the convention that the MSB of the compressed representation of the component has index $B\_max$ and the least significant bit (LSB) of the compressed representation of the component has index $B\_min$ . Accordingly, the total number of bits in the error field of a block of clipped error samples in compressed representation shall be $2 \times F\_block \times (B\_M - B\_L + 1)$ . + +The $B\_M$ fields shall include parameter $B\_M$ represented as a 4-bit unsigned integer, in the range from 0 to 15. + +NOTE – The parameter $B\_L$ is not reported as it can be calculated by the VCE from the clipped error sample control parameters (see equations 7-1 and 7-2) and the value of the reported $B\_M$ parameter. + +The format of the error block is presented in Figure 7-8. All parameters and clipped error samples shall be mapped with the MSB at the left side so that the MSB is transmitted first (i.e., the first transmitted bit is the MSB of the $B\_M$ field). + +Clipped error samples in the error field shall be mapped in ascending order of subcarrier index from left to right. For each clipped error sample, the $q\_x$ (real) component shall be mapped left from the $q\_y$ (imaginary) component. + +![Figure 7-8: Format of an error block. The diagram shows a horizontal sequence of fields. The first field is 'B_M' (4 bits). This is followed by a series of error sample components. Each component consists of a 'q_x component' and a 'q_y component', each of size 'B_M - B_L + 1' bits. The first pair is labeled 'First error sample', the second 'Second error sample', and so on, indicated by ellipses. Below these, the first pair is also labeled 'First clipped error sample' and the second 'Second clipped error sample'. A bracket below the error samples indicates 'F_block clipped error samples'. At the very bottom, a long bracket indicates the total size: 'Error block consists of (4 + F_block x 2 x (B_M - B_L + 1)) bits'. The diagram is labeled G.993.5(15)_F7-8.](933ecd14c858bf3fc919222d8e357bc8_img.jpg) + +Figure 7-8: Format of an error block. The diagram shows a horizontal sequence of fields. The first field is 'B\_M' (4 bits). This is followed by a series of error sample components. Each component consists of a 'q\_x component' and a 'q\_y component', each of size 'B\_M - B\_L + 1' bits. The first pair is labeled 'First error sample', the second 'Second error sample', and so on, indicated by ellipses. Below these, the first pair is also labeled 'First clipped error sample' and the second 'Second clipped error sample'. A bracket below the error samples indicates 'F\_block clipped error samples'. At the very bottom, a long bracket indicates the total size: 'Error block consists of (4 + F\_block x 2 x (B\_M - B\_L + 1)) bits'. The diagram is labeled G.993.5(15)\_F7-8. + +**Figure 7-8 – Format of an error block** + +#### 7.2.3.3 Backchannel data rate (informative) + +In case $F\_block = \left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$ , the number of bytes in the VBB-vb, following from Figures 7-6, 7-7 and 7-8 is: + +$$N\_VBB(vb) = \left\lceil \frac{24 + F\_block(vb) \times 2 \times (B\_M(vb) - B\_L(vb) + 1)}{8} \right\rceil$$ + +where $B\_M(vb)$ represents the $B\_M$ parameter for the vectored band number $vb$ , and $B\_L(vb)$ represents the $B\_L$ parameter for the vectored band $vb$ . + +Note that in general this value is not fixed, but may be different from one error report to the next, depending on the exact values of the clipped error samples. If padding (see Table 7-1) is used, on the other hand, the number of bytes in the VBB-vb only depends on the clipped error sample control parameters and not on the values of the clipped error sample values: + +$$N\_VBB(vb) = \left\lceil \frac{24 + F\_block(vb) \times 2 \times L\_w(vb)}{8} \right\rceil$$ + +In case $F\_block = 32$ , the number of bytes in the VBB-vb, following from Figures 7-6 and 7-8 is: + +$$N\_VBB(vb) = 2 + \sum_{eb=0}^{N\_block(vb)-1} (1 + 8 \times (B\_M(vb, eb) - B\_L(vb, eb) + 1))$$ + +where $B\_M(vb,eb)$ represents the $B\_M$ parameter for the error block number $eb$ of vectored band number $vb$ , $B\_L(vb,eb)$ represents the $B\_L$ parameter for the error block number $eb$ of vectored band $vb$ . + +Note that in general this value is not fixed, but may be different from one error report to the next, depending on the exact values of the clipped error samples. If padding (see Table 7-1) is used, the number of bytes in the VBB- $vb$ only depends on the clipped error sample control parameters and not on the values of the clipped error sample values: + +$$N\_VBB(vb) = 2 + N\_block(vb) \times (1 + 8 \times L\_w(vb))$$ + +In case $F\_block = 1$ , padding is used and the number of bytes in the VBB- $vb$ only depends on the clipped error sample control parameters and not on the values of the clipped error sample values: + +$$N\_VBB(vb) = \left\lceil \frac{8 + N\_block(vb) \times (4 + 2 \times L\_w(vb))}{8} \right\rceil$$ + +The $N\_ERB$ can be calculated as: + +$$N\_ERB = 1 + \sum_{vb=0}^{N\_band-1} report(vb) \times N\_VBB(vb)$$ + +where $report(vb) = 1$ if the VBB- $vb$ is included in the ERB (i.e., $L\_w > 0$ for band number $vb$ ), and $report(vb) = 0$ if the VBB- $vb$ is not included in the ERB (i.e., $L\_w = 0$ for band number $vb$ ). + +The backchannel data rate (BDR) for transmission of the error report block for each sync symbol is: + +$$BDR = 8 \times N\_ERB \times (f_{DMT} / 257)$$ + +where $f_{DMT}$ is the symbol rate (in symbols/s) defined in clause 10.4.4 of [ITU-T G.993.2]. + +The BDR is not defined when padding is not used. In that case, $N\_ERB$ varies from error report to error report. + +### 7.2.4 Identification of the ERB during Showtime + +At each of the sync symbol counts indicated by the VTU-O, the VTU-R shall transmit a single ERB. With each ERB, the VTU-R shall also transmit the downstream sync symbol count (as defined in clause 7.3.2) as identification of the downstream sync symbol the ERB corresponds to. The VTU-O shall indicate such sync symbol counts using the following time identification control parameters: + +- the error sample update period ( $m$ ); +- the error sample shift period ( $z$ ). + +The error sample update period gets value of $m$ if the error sample has to be reported on every $m$ -th sync symbol, i.e., on the sync symbol positions with sync symbol counts $SSC = m \times P + k$ , where $P$ is any integer in the range from 0 to $\lfloor (N\_SSC - 1 - k) / m \rfloor$ , and $k$ is the offset, which is an integer in the range from 0 to $m-1$ . which is an integer in the range from 0 to $m-1$ . After the SSC counter wraps around at the value of $N\_SSC-1$ , the next sync symbol count at which ERB shall be reported is $SSC = k$ (this count is obtained by setting $P=0$ ). + +The VTU-R shall set $k=0$ for the first report after the VTU-O's Error Feedback request. This report shall be sent for the first available sync symbol with SSC count that is a multiple of $m$ after reception of the ERB request (see clause 8.1). If $z > 0$ , the VTU-R shall increase $k$ by 1 after each error sample shift period of $z$ reports, wrapping around $k$ at $m-1$ . + +If $m = 1$ , the VTU-R shall report on each sync symbol. The error sample update period value of $m = 0$ is special and shall be used to indicate that the VTU-R shall stop error sample reporting. The non-zero error sample shift period $z$ is valid only for $m > 1$ . The error sample shift period value of $z = 0$ shall be used if no error sample shift is to be done and if $m=1$ . + +NOTE 1 – The parameters $m$ and $z$ should be selected such that the error samples are reported at least once for all the bits of the pilot sequence after a certain time. + +NOTE 2 – For example, with $N\_SSC = 1024$ , $m = 3$ , and the first report sent at $SSC = 6$ , the reports are on the following sync symbol counts: + +$m = 3$ and $z = 0$ then $SSC = 6, 9, \dots, 1020, 1023, 0, 3, 6, 9, \dots$ + +$m = 3$ and $z = 128$ then $SSC = 6, 9, \dots, 128 \times 3, 129 \times 3, 130 \times 3 + 1, 131 \times 3 + 1, \dots, 257 \times 3 + 1, 258 \times 3 + 2, 259 \times 3 + 2, \dots, 340 \times 3 + 2, 2, 5, \dots, 44 \times 3 + 2, 45 \times 3, 46 \times 3, 47 \times 3, \dots$ + +The values for the time identification control parameters are defined in Table 7-4. + +**Table 7-4 – Values of time identification control parameters** + +| Parameter | Valid values for VCE | Mandatory values for VTU-R to support | +|-----------|------------------------------------------------------------|---------------------------------------| +| $m$ | 0, 1, 2, ..., 63, 64 | All valid values | +| $z$ | If $m > 1$ : 0, 2, ..., 254, 255, 256
If $m \leq 1$ : 0 | All valid values | + +## 7.3 Upstream vectoring requirements for the VTU-R + +The VTU-R shall comply with [ITU-T G.993.2], with the exceptions and additional requirements contained in this Recommendation. + +In order to enable the VCE to fulfil the tasks described in clause 6.1, the VTU-R shall support the requirements in the following clauses. + +### 7.3.1 Symbol alignment + +Under VCE control, all VTU-Rs in the vectored group shall use the same subcarrier spacing and symbol rate. + +NOTE – The VCE may control the alignment of symbols from different lines of the vectored group at the U-O2 reference point (defined in Figure 5-4 of [ITU-T G.993.2]) by adjusting the timing advance (TA) of these lines during initialization (see clause 10). + +### 7.3.2 Sync symbol position + +The VTU-R shall have the capability to transmit sync symbols as defined in clause 10.2 of [ITU-T G.993.2]. The VTU-R shall transmit sync symbols at time positions assigned by the VCE and communicated to the VTU-R during initialization. The time position of upstream sync symbols is defined by an offset between upstream and downstream sync symbol positions. + +The offset between the upstream and downstream sync symbol time positions is set by the VCE and sent to the VTU-R in the O-SIGNATURE message. + +The VCE may configure all VTU-Rs in the vectored group to transmit upstream sync symbols at the same time positions or at different time positions for one or more VTU-Rs in the vectored group. + +The VTU-R shall keep a downstream sync symbol counter (MODULO $N\_SSC$ ), counting continuously over Showtime. The counter value of the first downstream sync symbol transmitted in Showtime shall be set by the VTU-R to the value of the field First SSC of the first received Error Feedback command (see Table 8-3). Before receiving the first Error Feedback command, the value of the downstream sync symbol counter for the first downstream sync symbol transmitted in Showtime is vendor discretionary. + +NOTE – This setting at the start of Showtime synchronizes the downstream sync symbol counter with the VTU-O/VCE (see clause 6.2.2). + +### 7.3.3 Modulation of pilot sequence + +The VTU-R shall have the capability to modulate a VCE-specified upstream pilot sequence on all subcarriers of the upstream sync symbols during initialization (see clause 10.3.4.1) and on the probe tones (see clause 3.2.10) of the upstream sync symbols during Showtime. The upstream pilot sequence is vendor discretionary, determined by the VCE, with length $Npilot\_us$ and sent to the VTU-R at initialization in the O-SIGNATURE message. Pilot sequence bits are indexed from 0 to $Npilot\_us - 1$ . The bit with index 0 shall be transmitted first, followed by the bit with index 1, up to bit with index $Npilot\_us - 1$ . If the "pilot sequence length multiple of 4" is enabled (see clause 10.2), then valid values of $Npilot\_us$ are all multiples of 4 in the range from 8 to 512. Otherwise, the valid values of $Npilot\_us$ shall be all powers of 2 in the range from 8 to 512. The pilot sequence shall be cyclically repeated after $Npilot\_us$ bits, except for the case where the upstream pilot sequence is changed by the VCE through the procedure defined in clause 8.2. + +The time position of the upstream pilot sequence is determined by the VCE and communicated to VTU-R during the initialization by special markers (see clause 10.3.3.5). Subcarriers of upstream sync symbols shall be modulated by the upstream pilot sequence bits corresponding to the time position of the upstream pilot sequence. + +In Showtime, the first upstream sync symbol position shall be as defined in clause 10.6. + +The modulation of a pilot sequence on the probe tones (see clause 3.2.10) of sync symbols is defined as whether the sync frame bits modulated onto the probe tones are set to either 00 (if the pilot sequence bit is ZERO) or set to 11 (if the pilot sequence bit is ONE). Over the tones of a particular sync symbol, the pilot sequence bit shall have a periodicity of 10 tones (considering both probe and flag tones). + +If upstream frequency dependent pilot sequence (upstream FDPS) is enabled through ITU-T G.994.1, then eight pilot sequences with indices from 0 to 7 are defined. The pilot sequences #(0,1,2,3,4,5,6,7) shall be modulated onto tone indices $10n+(0,2,3,4,5,6,8,9)$ respectively. All eight pilot sequences shall have the same length $Npilot\_us$ . All pilot sequences shall start at the same sync symbol position. + +The sync frame bits modulated on the flag tones (see clause 3.2.6) shall be used for the transmission of a Syncflag as defined in clause 10.5.3 of [ITU-T G.993.2]. The sync frame shall be modulated onto a sync symbol as defined in clause 10.5 of [ITU-T G.993.2] (including the quadrant scrambling of all MEDLEY subcarriers, regardless of it being a flag or a probe tone). + +## 7.4 Requirements for the NT system + +The NT (see Figure 5-1) shall support downstream vectoring. + +### 7.4.1 Layer 2 Ethernet encapsulation of the backchannel data + +If the VCE selects to use this encapsulation type, the backchannel data shall be encapsulated as defined in this clause. + +Within the NT, the clipped error samples are first sent from the VTU-R to the L2+ functional block, where they are encapsulated into the Layer 2 transport protocol and multiplexed into one of the upstream Ethernet (or Ethernet over ATM) data streams. + +Ethernet encapsulation is based on [IEEE 802.3] and shall be as described in this clause. + +The Layer 2 Ethernet frame encapsulation shall consist of the following fields: + +- Destination MAC address shall be MAC address of the VCE; +- Source MAC address shall be the MAC address of the VTU-R; + +- Length field (as per the IEEE 802.3 MAC frame format [IEEE 802.3]); +- LLC PDU header coding for SNAP protocol (3 bytes, AA-AA-03); +- SNAP PDU header containing a 3-octet ITU OUI 00-19-A7 + 2-octet Protocol ID of ITU subtype 00-03 for a PRIVATE protocol; +- Protocol payload data (Line\_ID, Sync Symbol Count, Segment Code and Backchannel Data); +- Padding (only for the last segment and as per the IEEE 802.3 MAC frame format [IEEE 802.3]); +- Standard Ethernet 4-byte FCS (as per the IEEE 802.3 Ethernet frame FCS [IEEE 802.3]). + +The VCE MAC Address field shall contain the VCE MAC Address as configured by the VCE through O-PMS, see clause 10.5.2.1. The protocol payload data shall contain the Line\_ID (as configured by the VCE through O-PMS, see clause 10.5.2.1), the Sync Symbol Count (as defined in clause 7.2.4), the Segment Code (as defined in [ITU-T G.993.2]) and the backchannel data ERB (as defined in clause 7.2.3). The Length field shall equal the length of the protocol payload data, increased with the 8-byte LLC SNAP header length, and shall not exceed 1024+8=1032. If the protocol payload data exceeds 1024 bytes, the backchannel data ERB shall be segmented as defined in clause 11.2.3.1 of [ITU-T G.993.2]. For protocol payload data lengths shorter than or equal to 1024 bytes, the backchannel data ERB may also be segmented. If segmented, each segment of the backchannel data ERB shall be Layer 2 Ethernet encapsulated as shown in Figure 7-9, with the number of segments per backchannel data ERB not exceeding 16. + +The format of the Ethernet encapsulated backchannel data ERB is shown in Figure 7-9. + +![Diagram of the Ethernet encapsulation of backchannel data message. The diagram shows a vertical stack of fields. From top to bottom: VCE MAC ADDRESS (6 bytes), VTU-R MAC ADDRESS (6 bytes), LENGTH <= 1032 (2 bytes), LLC HEADER (3 bytes), ITU-T OUI (3 bytes), PROTOCOL ID (2 bytes), LINE ID (2 bytes), SYNC SYMBOL COUNT (2 bytes), SEGMENT CODE (2 bytes), Backchannel data / Error report block (ERB) (N_ERB bytes), PADDING, and FCS (4 bytes). A vertical double-headed arrow on the right side, labeled 'Protocol payload data', spans from the LINE ID field down to the end of the Backchannel data/ERB field. The diagram is labeled G.993.5(15)_F7-9 at the bottom right.](2837ffdadcdb1e5bababa56b564e56ed_img.jpg) + +Diagram of the Ethernet encapsulation of backchannel data message. The diagram shows a vertical stack of fields. From top to bottom: VCE MAC ADDRESS (6 bytes), VTU-R MAC ADDRESS (6 bytes), LENGTH <= 1032 (2 bytes), LLC HEADER (3 bytes), ITU-T OUI (3 bytes), PROTOCOL ID (2 bytes), LINE ID (2 bytes), SYNC SYMBOL COUNT (2 bytes), SEGMENT CODE (2 bytes), Backchannel data / Error report block (ERB) (N\_ERB bytes), PADDING, and FCS (4 bytes). A vertical double-headed arrow on the right side, labeled 'Protocol payload data', spans from the LINE ID field down to the end of the Backchannel data/ERB field. The diagram is labeled G.993.5(15)\_F7-9 at the bottom right. + +Figure 7-9 – Format of the Ethernet encapsulation of backchannel data message + +### 7.4.2 eoc encapsulation of the backchannel data + +If the VCE selects to use this encapsulation type, the backchannel data shall be communicated using the eoc protocol described in clause 8.1. + +# 8 Vectoring-specific eoc messages + +The VTU-O and VTU-R VME shall use the eoc commands and responses defined in this clause to support vectoring. For vectoring-related eoc commands and responses, both the VTU-O and VTU-R + +shall use the standard eoc protocol for message communication defined in clause 11.2.2 of [ITU-T G.993.2] and the protocol for commands and responses defined in clause 11.2.3 of [ITU-T G.993.2], except for the protocol for the Error Feedback command and responses, which shall be as defined in clause 8.1. + +The list of additional eoc commands to facilitate operation of vectored lines is presented in Table 8-1 (high priority) and Table 8-2 (normal priority). + +**Table 8-1 – High priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | +|------------------------------------------|----------------------|---------------------------------------------------------------------------------|-----------------------------------------------------------------------| +| Error Feedback
0001 1000 2 | From VTU-O to VTU-R | Request for error samples for the given vectored band and with the given format | eoc encapsulated error samples and associated parameters, ACK or NACK | + +**Table 8-2 – Normal priority commands and responses** + +| Command type and assigned value | Direction of command | Command content | Response content | +|-------------------------------------------------|----------------------|-------------------------------------------|------------------| +| Pilot sequence update
0001 0001 2 | From VTU-O to VTU-R | Request to update upstream pilot sequence | Acknowledgement | + +## 8.1 eoc messages for backchannel configuration + +The VTU-O VME shall use the Error Feedback command and responses for obtaining clipped error samples from the VTU-R VME and for updates of backchannel control parameters. The command (request for clipped error samples) may be initiated only by the VTU-O and shall use the format shown in Table 8-3; the VTU-R shall respond with clipped error samples for the requested subcarriers in the requested format, or with ACK (if error samples are communicated over L2-based backchannel), or with NACK. The NACK provides a rejection code describing the reason of the request denial. Prior to sending the NACK, the VTU-R VME shall suspend sending clipped error samples until it receives a new Error Feedback command with a valid set of backchannel and error report control parameters. The VTU-R shall use the format of the response message as described in Table 8-6 or Table 8-7. The rejection codes shall be as described in Table 8-8. + +The first octet of the command and the response shall be the assigned value of the Error Feedback command type, as shown in Table 8-1. The second and subsequent octets shall be as shown in Table 8-3 for the command and in Table 8-6 or Table 8-7 for responses. The communicated data octets shall be mapped using the generic format described in clause 11.2.3.1 of [ITU-T G.993.2]. + +The VTU-O sends an Error Feedback command to request the VTU-R to start sending clipped error samples with particular parameters. The command indicates: + +- the error sample update period (*m*); +- the error sample shift period (*z*); +- the range of subcarrier indices to be covered in the report (defined by vectored downstream bands); +- the error report control parameters (*F\_sub*, *F\_block*, *B\_min*, *B\_max*, *L\_w*, etc.). + +Upon reception of the command, the VTU-R shall either start sending clipped error samples (Error Feedback data messages as defined in Table 8-6 for the eoc backchannel, and in Table 8-7 for the L2 backchannel) or respond with a NACK (as defined in Table 8-8). The first Error Feedback data + +message is an ACK that the Error Feedback command was admitted. More Error Feedback data messages may be transmitted if necessary (either as subsequent eoc messages or as L2 Ethernet packets). Transmissions of Error Feedback data messages shall be triggered by every error sample update sync symbol counts requested in the Error Feedback command (update period and shift period). If the update period is more than 1, the VTU-R shall update error samples at the exact sync symbol counts indicated by the VTU-O. + +Error Feedback data messages shall not be acknowledged. If the Error Feedback data message exceeds 1024 bytes, it shall be segmented as defined in clause 11.2.3.1 of [ITU-T G.993.2] with the maximum number of segments not to exceed 16; segments shall be sent without waiting for IACK. The VTU-R shall not retransmit Error Feedback data messages or their segments. If the VTU-O does not receive the response (ACK), it may send another Error Feedback command, possibly with different control parameters. The VTU-R shall continue sending Error Feedback data messages while waiting for Syncflag after an OLR command. If in the time period allocated to send a particular Error Feedback data message the eoc channel is busy with another high-priority message (e.g., OLR command), the VTU-R shall drop this Error Feedback data message and continue with the next Error Feedback data message. + +At the start of Showtime, the VTU-R shall not send clipped error samples until it receives an Error Feedback command with a valid set of backchannel and error report control parameters. To start communication of clipped error samples, the VTU-O shall send a backchannel configuration eoc command within the first second of Showtime. To stop communication of clipped error samples, the VTU-O shall send an Error Feedback command that carries a special backchannel configuration (i.e., error sample update period $m=0$ , see Table 8-3). Upon reception of the command, the VTU-R shall first stop sending Error Feedback data messages and subsequently respond with NACK. + +**Table 8-3 – Error Feedback command transmitted by the VTU-O** + +| Name | Length (octets) | Octet number | Content | +|------------------------|------------------------------------------------|--------------------------------------------------|------------------------------------------------------------------------| +| Error Feedback request | $9 + 5 \times N\_band$
( $N\_band \leq 8$ ) | 2 | 01 16 (Note 1) | +| | | 3 to 4 | First SSC (see clause 6.2.2, clause 7.3.2 and Note 6) | +| | | 5 | Error sample update period ( $m$ ) (see clause 7.2.4 and Note 2) | +| | | 6 to 7 | Error sample shift period ( $z$ ) (see clause 7.2.4 and Note 3) | +| | | 8 to $8 + 3 \times N\_band$ | Vectored bands descriptor (see Table 12-18 of [ITU-T G.993.2], Note 4) | +| | | $9 + 3 \times N\_band$ to $9 + 5 \times N\_band$ | Error report configuration descriptor (Note 5) | + +NOTE 1 – All other values are reserved by ITU-T. + +NOTE 2 – The error sample update period ( $m$ ) shall be represented as an unsigned integer. + +NOTE 3 – The error sample shift period ( $z$ ) shall be represented as an unsigned integer. + +NOTE 4 – The value of $N\_band$ is defined as octet 1 of the ITU-T G.993.2 band descriptor + +NOTE 5 – This descriptor defines $N\_band$ sets of clipped error sample reporting parameters defined in clause 7.2.2 for each downstream vectored band (2 octets per band). It shall use the format defined in Table 8-4. + +NOTE 6 – The value of the First SSC shall be the same for all error feedback commands after entering Showtime. + +**Table 8-4 – Error report configuration descriptor** + +| Parameter | Bit | Octet number | Description | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|----------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| N_band | [7:4] | 0 | The number of configured vectored bands in the range from 1 to 8 represented as an unsigned integer | +| padding | 3 | | As defined in clause 7.2.2. | +| Reserved by ITU-T | 2 | | Shall be set to 0 2 . | +| F_block | [1:0] | | Block size, encoded as (see Note):
$00_2 - F\_block = \left\lceil \frac{N\_carrier}{F\_sub} \right\rceil$
$01_2 - F\_block = 1$
$10_2 - F\_block = 32$
11 2 – Reserved for use by ITU-T | +| Parameters for vectored band 1 | | 1-2 | See Table 8-5 | +| | | | | +| Parameters for vectored band N_band | | $2 \times N\_band - 1$ to $2 \times N\_band$ | See Table 8-5 | +| NOTE – If encoded 01 2 or 10 2 , then F_block has the same value for all vectored bands. If encoded 00 2 , then F_block may have a different value for each vectored band depending on the number of subcarriers ( N_carrier ) and subsampling ( F_sub ). | | | | + +**Table 8-5 – Vectored band control parameters** + +| Parameter | Bits | Octet number | Description | +|--------------|-------|--------------|-------------------------------------------------------------------------------------------------------------------------------------------------| +| F_sub | [7:4] | 0 | Sub-sampling rate F_sub as defined in clause 7.2.2, with $\log_2(F\_sub)$ represented as unsigned integer. | +| L_w | [3:0] | | Length of the clipped error sample in compressed representation as defined in clause 7.2.2, with L_w represented as an unsigned integer. | +| B_min | [7:4] | 1 | Parameter B_min as defined in clause 7.2.2, with B_min represented as an unsigned integer. | +| B_max | [3:0] | | Parameter B_max as defined in clause 7.2.2, with B_max represented as an unsigned integer. | + +**Table 8-6 – Error Feedback response transmitted by the VTU-R for eoc backchannel** + +| Name | Length (Octets) | Octet number | Content | +|-------------------------|-----------------|--------------------|---------------------------------------------------------------------------------------------------------------| +| Error Feedback data/ACK | $5 + N_{ERB}$ | 2 | $80_{16}$ (see Note 1) | +| | | 3-4 | Sync symbol count (SSC) represented as unsigned integer in the range as defined in clause 7.3.2 (see Note 2). | +| | | 5 | Segment code (SC), represented as defined in clause 11.2.3.3 of [ITU-T G.993.2]. | +| | | 6 to $5 + N_{ERB}$ | Backchannel data, represented with $N_{ERB}$ octets as defined in clause 7.2.3 (see Note 3). | +| NACK | 3 | 2 | $81_{16}$ (see Note 1) | +| | | 3 | 1 octet for reason code (see Table 8-8) | + +NOTE 1 – All other values for this octet are reserved by ITU-T. +NOTE 2 – This field identifies the downstream sync symbol for which clipped error samples are reported. +NOTE 3 – This field shall carry the ERB using the format described in clause 7.2.3. + +**Table 8-7 – Error Feedback response transmitted by the VTU-R for L2 backchannel** + +| Name | Length (Octets) | Octet number | Content | +|------|-----------------|--------------|-------------------------------------------------| +| ACK | 6 | 2 | $80_{16}$ (see Note 1) | +| | | 3-4 | Both octet shall be set to $00_{16}$ | +| | | 5 | Octet shall be set to $11000000_2$ (see Note 2) | +| | | 6 | Octet shall be set to $00_{16}$ (see Note 3). | +| NACK | 3 | 2 | $81_{16}$ (see Note 1) | +| | | 3 | 1 octet for reason code (see Table 8-8) | + +NOTE 1 – All other values for this octet are reserved by ITU-T. +NOTE 2 – This value corresponds with the segment code of a non-segmented eoc message as defined in clause 11.2.3.3 of [ITU-T G.993.2]. +NOTE 3 – This field shall serve as ACK indicating that the backchannel configuration required by Error Feedback command was accepted. + +**Table 8-8 – NACK reason codes** + +| Value | Definition | +|------------------------------------------------------|-------------------------------------------------------------------------------| +| $01_{16}$ | Invalid set of error sample parameters or clipped error sample report format. | +| $02_{16}$ | VTU-R stops sending error reports on the VCE's request. | +| NOTE – All other reason codes are reserved by ITU-T. | | + +## 8.2 Pilot sequence update command and response + +The VTU-O VME shall use the pilot sequence update command and response to force an update of the upstream pilot sequence(s) and communicate the updated pilot sequence(s) for the vectored line (see clause 7.3.3) to the VTU-R VME. Separate commands are defined for updating a single pilot sequence (in case upstream FDPS is disabled through ITU-T G.994.1) and for updating eight upstream pilot sequences (in case upstream FDPS is enabled through ITU-T G.994.1). These commands are shown in Table 8-9, and may be initiated only by the VTU-O; the VTU-R shall respond with the ACK, using the format shown in Table 8-10. + +The first octet of the command shall be the assigned value of the pilot sequence update command type, as shown in Table 8-2. The second and subsequent octets shall be as shown in Tables 8-9 for commands and in Table 8-10 for responses. The data octets shall be mapped using the format described in clause 11.2.3.1 of [ITU-T G.993.2]. + +Using the pilot sequence update message, the VCE may update the upstream pilot sequence(s). + +The command message length depends on the length of the upstream pilot sequence ( $N_{pilot\_us}$ bits, see clause 7.3.3). Only the upstream pilot sequence bits may be changed during Showtime. The newly assigned upstream pilot sequence length shall be the same as the length of the upstream pilot sequence that was set at initialization. + +The command message bytes shall be defined as shown in Table 8-9. + +**Table 8-9 – Pilot sequence update commands transmitted by the VTU-O** + +| Name | Length (Octets) | Octet number | Content | +|--------------------------------------------------------------------|------------------------------------------------------------|---------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Pilot sequence configuration (FDPS disabled through ITU-T G.994.1) | $3 + N_{pilot\_us}/8$ | 2 | 01 16 for change of upstream pilot sequence with upstream FDPS disabled through ITU-T G.994.1 (see Note) | +| | | 3 | 01 16 if interruption of current upstream pilot sequence is not allowed;
02 16 if interruption of current upstream pilot sequence is allowed (see Note) | +| | | 4 to $3 + \lceil N_{pilot\_us}/8 \rceil$ | Upstream pilot sequence bits, coded as defined for field #4 in Table 10-7. | +| Pilot sequence configuration (FDPS enabled through ITU-T G.994.1) | $11 + (N_{aips} + 1) \times \lceil N_{pilot\_us}/8 \rceil$ | 2 | 02 16 for change of upstream pilot sequences with upstream FDPS enabled through ITU-T G.994.1 (see Note) | +| | | 3 | 01 16 if interruption of current upstream pilot sequence is not allowed;
02 16 if interruption of current upstream pilot sequence is allowed (see Note) | +| | | 4 to $3 + \lceil N_{pilot\_us}/8 \rceil$ | Upstream pilot sequence bits, coded as defined for field #4 in Table 10-7. | +| | | $4 + \lceil N_{pilot\_us}/8 \rceil$ to $11 + (N_{aips} + 1) \times \lceil N_{pilot\_us}/8 \rceil$ | The upstream FDPS descriptor as defined in Table 10-9. | + +NOTE – All other values for this octet are reserved by ITU-T. + +The third octet of the pilot sequence update command defines the time at which the upstream pilot sequence change shall occur: + +- If interruption of the current upstream pilot sequence is not allowed (value $01_{16}$ ), the upstream pilot sequence change shall be applied starting from the next sync symbol position after the end of the current upstream pilot sequence, i.e., after the sync symbol that modulates the last bit of the old upstream pilot sequence, the next sync symbol shall modulate the first bit of the new upstream pilot sequence. +- If interruption of the current upstream pilot sequence is allowed (value $02_{16}$ ), the upstream pilot sequence change may occur at any sync symbol position, i.e., after the sync symbol that modulates bit $i$ of old upstream pilot sequence, the next sync symbol shall modulate bit $i+1$ of the new upstream pilot sequence. + +The only allowed response from the VTU-R is to acknowledge the correct reception of the command, as shown in Table 8-10. + +**Table 8-10 – Pilot sequence update response transmitted by the VTU-R** + +| Name | Length (Octets) | Octet number | Content | +|------|-----------------|--------------|------------------------------------------| +| ACK | 2 | 2 | $80_{16}$ (see Note) | +| NACK | 3 | 2 | $81_{16}$ (see Note) | +| | | 3 | 1 octet for reason code (see Table 8-11) | + +NOTE – All other values for this octet are reserved by ITU-T. + +**Table 8-11 – NACK reason codes** + +| Value | Definition | +|-----------|----------------------------| +| $01_{16}$ | Invalid set of parameters. | + +NOTE – All other reason codes are reserved by ITU-T. + +If the pilot sequence update command updates the upstream pilot sequence(s), the VTU-R shall apply the change only after sending the ACK message. If interruption of the current pilot sequence(s) is allowed, the update should occur as soon as possible, and shall occur within 200 ms after sending the ACK message. + +The timing diagram of the pilot sequence eoc command and response is shown in Figure 8-1. + +![Timing diagram showing the interaction between VTU-O and VTU-R. VTU-O sends a 'Command' to VTU-R. VTU-R responds with a 'Response' back to VTU-O. Between the Command and Response, VTU-R transmits the 'old upstream pilot sequence(s)'. After receiving the Response, VTU-R transmits the 'new upstream pilot sequence(s)'. The diagram includes vertical lines for VTU-O and VTU-R, and arrows for the Command and Response messages. A label G.993.5(15)_F8-1 is present at the bottom right.](23b48e0b60d0b6deb0cc9862ff4b8ead_img.jpg) + +Timing diagram showing the interaction between VTU-O and VTU-R. VTU-O sends a 'Command' to VTU-R. VTU-R responds with a 'Response' back to VTU-O. Between the Command and Response, VTU-R transmits the 'old upstream pilot sequence(s)'. After receiving the Response, VTU-R transmits the 'new upstream pilot sequence(s)'. The diagram includes vertical lines for VTU-O and VTU-R, and arrows for the Command and Response messages. A label G.993.5(15)\_F8-1 is present at the bottom right. + +**Figure 8-1 – Timing diagram of the pilot sequence update command and response** + +## **8.3 Power management commands and responses** + +The same power management commands and responses shall be used as defined in clause 11.2.3.9 of [ITU-T G.993.2]. The orderly shutdown procedures described in clauses 11.2.3.9.1 and 11.2.3.9.2 of [ITU-T G.993.2] shall be modified as defined in this clause. + +### **8.3.1 L3 Request by VTU-R (replaces clause 11.2.3.9.1 of [ITU-T G.993.2])** + +Upon receipt of the L3 Request command, the responding VTU-O shall send either the Grant or Reject response. The proposed link state shall be formatted as 0316 for the L3 link state. If any other link state is received, the Reject response shall be sent with the reason code 0216. + +The VTU-O may reject a request to move to link state L3 using reason code 0116 because it is temporarily busy, or reject it using code 0316 because it has local knowledge that the L3 state is not desired at this time. + +When the VTU-R receives the Grant response, the VTU-R shall transition from the R-SHOWTIME state to R-SILENT (see Figure 12-3). Upon entering the R-SILENT state, the VTU-R shall not yet change the input impedance as seen from the line at the U-R2 reference point. + +When the VTU-O detects that the VTU-R has stopped transmission (because the VTU-R transitioned to the R-SILENT state), the VTU-O shall transition from the O-SHOWTIME state to the O-DEACTIVATING state. + +Controlled by the VCE, the VTU-O shall transition from the O-DEACTIVATING state to the O-SILENT state. + +When the VTU-R detects that the VTU-O has stopped transmission (because the VTU-O transitioned to the O-DEACTIVATING state or the O-SILENT state), the VTU-R may change the characteristics of the transmission path. However, for the sake of vectoring stability of the vectored group, the VTU-R should maintain approximately the input impedance as seen from the line at the U-R2 reference point. + +### **8.3.2 L3 Request by VTU-O (replaces clause 11.2.3.9.2 of [ITU-T G.993.2])** + +Upon receipt of the L3 Request command, the responding VTU-R shall send either the Grant or Reject response. The proposed link state shall be formatted as 0316 for the L3 link state. If any other link state is received, the Reject response shall be sent with the reason code 0216. + +The VTU-R may reject a request to move to link state L3 using reason code 0116 because it is temporarily too busy, or reject it using code 0316 because it has local knowledge that the L3 state is not desired at this time. + +When the VTU-O receives the Grant response, the VTU-O shall transition from the O-SHOWTIME state to the O-DEACTIVATING state. In the O-DEACTIVATING state, the VTU-O shall not yet change the input impedance as seen from the line at the U-O2 reference point. + +Controlled by the VCE, the VTU-O shall transition from the O-DEACTIVATING state to the O-SILENT state. Upon entering the O-SILENT state, the VTU-O shall still not change the input impedance as seen from the line at the U-O2 reference point. + +When the VTU-R detects that the VTU-O has stopped transmission (because the VTU-O transitioned to the O-DEACTIVATING state or the O-SILENT state), the VTU-R shall transition from the R-SHOWTIME state to the R-SILENT state. + +When the VTU-O detects that the VTU-R has stopped transmission (because the VTU-R transitioned to the R-SILENT state), the VTU-O may change the characteristics of the transmission path. However, for the sake of vectoring stability of the vectored group, the VTU-O should maintain approximately the input impedance as seen from the line at the U-O2 reference point. + +# 9 Activation and deactivation of pairs in a vectored group + +The activation of a line in a vectored group is achieved through the initialization procedure defined in clause 10. + +The deactivation of a line from the vectored system also requires an orderly procedure. If the line to be deactivated is used in upstream or downstream FEXT cancellation, then the performance of the vectoring system may suffer from an abrupt disconnection. The procedures for an "Orderly shutdown event" and for a "Disorderly shutdown event" are described in this clause. + +## 9.1 Orderly shutdown event + +The orderly shutdown event shall consist of a power management transition to line state L3. The related power management commands and responses are defined in clause 8.3. + +## 9.2 Disorderly shutdown event + +Upon detection of a near-end *los* defect, (see clause 11.3.1.3 of [ITU-T G.993.2]), the VTU-O shall transition from the O-SHOWTIME state to the O-DEACTIVATING state. + +Controlled by the VCE, the VTU-O shall transition from the O-DEACTIVATING state to the O-SILENT state. + +NOTE – If errors on the other lines in the vectored group are acceptable, an additional and/or alternative technique to the switching-off of the transmit signal, is fast update of the coefficients. This may be effectuated as follows. When a disorderly shutdown event (DSE) or other disorderly event is detected on a line, the VTU-Os of the other lines should send error feedback requests preferably using robust eoc channel to their VTU-Rs. The VTU-Rs should then provide the requested error samples to the respective VTU-Os in the vectoring feedback channel. Upon receiving the error samples, it is sufficient that the VCE estimates only the changed channel coefficients, i.e., the channel coefficients associated with the line subject to DSE, in order to update an estimate of the full channel. This can be performed using error samples corresponding to a few sync symbols only. Then, the VCE uses the updated channel estimate comprising the estimated changed channel coefficients and the unchanged channel coefficients to update the pre-coder. The duration of the period of errors, before the pre-coder is updated using such a fast update mechanism, has an approximate length of a few superframes, and therefore may avoid the other lines to retrain due to the DSE. + +# 10 Initialization of a vectored group + +This clause defines the initialization of a vectored group. + +## 10.1 Overview + +The initialization procedure described in this clause is based on ITU-T G.993.2 initialization with addition of steps for FEXT channel estimation. The final mode of vectored operation (i.e., downstream and upstream vectoring, or downstream only vectoring) is determined during the ITU-T G.994.1 Phase of initialization. + +Figure 10-1 provides an overview of the initialization procedure for both upstream and downstream directions. For this Recommendation, the ITU-T G.993.2 initialization phases are adopted with some modifications to the SOC messages and addition of initialization signals for FEXT channel estimation. The initialization signals added to the ITU-T G.993.2 Channel Discovery phase and Training phase are highlighted in Figure 10-1. + +If several lines are initialized simultaneously, the initialization procedures of these lines have to be aligned in time, so that all lines pass the vectoring-related phases simultaneously (see clauses 10.3.3.6 and 10.4.3.9). + +![Figure 10-1 – ITU-T G.993.5 initialization overview. The diagram shows two vertical flowcharts for 'Downstream direction' and 'Upstream direction'. Both start with 'ITU-T G.994.1 handshake phase'. The downstream path goes through 'O-P-VECTOR 1 Estimation of FEXT channels from the initializing line into vectored lines', 'ITU-T G.993.2 channel discovery phase', 'O-P-VECTOR 1-1 Re-estimation of FEXT channels from the initializing line into vectored lines', 'O-P-TRAINING V1', 'ITU-T G.993.2 training phase', 'O-P-VECTOR 2', 'O-P-VECTOR 2-1 Estimation of FEXT channels from and into the initializing line', and ends with 'ITU-T G.993.2 channel analysis and exchange phase'. The upstream path goes through 'R-P-VECTOR 1 Estimation of FEXT channels from the initializing line into vectored lines', 'ITU-T G.993.2 channel discovery phase', 'R-P-QUIET V1', 'R-P-VECTOR 1-1 Re-estimation of FEXT channels from the initializing line into vectored lines', 'ITU-T G.993.2 training phase', 'R-P-VECTOR 1-2 Re-estimation of FEXT channels from the initializing line into vectored lines', 'R-P-VECTOR 2 Estimation of FEXT channels from and into the initializing line', and ends with 'ITU-T G.993.2 channel analysis and exchange phase'. A small note 'G.993.5(15)_F10-1' is at the bottom right.](e8e818455bb0d1a6153299a388b94868_img.jpg) + +Figure 10-1 – ITU-T G.993.5 initialization overview. The diagram shows two vertical flowcharts for 'Downstream direction' and 'Upstream direction'. Both start with 'ITU-T G.994.1 handshake phase'. The downstream path goes through 'O-P-VECTOR 1 Estimation of FEXT channels from the initializing line into vectored lines', 'ITU-T G.993.2 channel discovery phase', 'O-P-VECTOR 1-1 Re-estimation of FEXT channels from the initializing line into vectored lines', 'O-P-TRAINING V1', 'ITU-T G.993.2 training phase', 'O-P-VECTOR 2', 'O-P-VECTOR 2-1 Estimation of FEXT channels from and into the initializing line', and ends with 'ITU-T G.993.2 channel analysis and exchange phase'. The upstream path goes through 'R-P-VECTOR 1 Estimation of FEXT channels from the initializing line into vectored lines', 'ITU-T G.993.2 channel discovery phase', 'R-P-QUIET V1', 'R-P-VECTOR 1-1 Re-estimation of FEXT channels from the initializing line into vectored lines', 'ITU-T G.993.2 training phase', 'R-P-VECTOR 1-2 Re-estimation of FEXT channels from the initializing line into vectored lines', 'R-P-VECTOR 2 Estimation of FEXT channels from and into the initializing line', and ends with 'ITU-T G.993.2 channel analysis and exchange phase'. A small note 'G.993.5(15)\_F10-1' is at the bottom right. + +**Figure 10-1 – ITU-T G.993.5 initialization overview** + +In the downstream direction, at the beginning of the Channel Discovery phase, the VTU-O of the initializing line transmits O-P-VECTOR 1 signal which comprises only sync symbols modulated by the pilot sequence and which is aligned with sync symbols of vectored lines, see Figure 10-2. The O-P-VECTOR 1 signal allows the VCE to estimate FEXT channels from the initializing lines into the vectored lines. The VCE estimates these FEXT channels based on the reported clipped error samples from the VTU-Rs of the vectored lines and enables the pre-coding in the VTU-Os of these vectored lines to cancel FEXT from the initializing lines into these vectored lines during the remainder of the initialization of the initializing lines. + +At the beginning of the Training phase, the initializing VTU-O will transmit O-P-VECTOR 1-1 signal, which is the same as O-P-VECTOR 1 and allows the VCE to update the downstream FEXT channel estimates from the initializing lines into the vectored lines, prior to transitioning into the ITU-T G.993.2 Training phase. + +After the ITU-T G.993.2 Training phase, the VTU-O transmits the O-P-VECTOR 2 signal, followed by the O-P-VECTOR 2-1 signal, which both comprise sync symbols modulated by the pilot sequence and regular symbols carrying the SOC, see Figure 10-3. During the transmission of O-P-VECTOR 2-1, the VCE estimates FEXT channels from all vectored lines into each initializing + +line and vice versa. Finally, at the end of the transmission of O-P-VECTOR 2-1, the whole FEXT channel matrix, including FEXT coefficients from the initializing line into the vectored lines and FEXT coefficients from the vectored lines into each initializing line, is estimated by the VCE. At this point the initialization process is complete and the initializing lines may be included in the pre-coding operation. After O-P-VECTOR 2-1 transmission is complete, the VTU-O of the initializing line enters the Channel Analysis and Exchange phase for estimation of the signal-to-noise ratio (SNR) and determination of the bit loading to be used during Showtime. + +In the upstream direction, in order to avoid excessive FEXT into vectored lines, the VTU-R of an initializing line, after detection of the O-SIGNATURE message in the Channel Discovery phase, starts transmitting an R-P-VECTOR 1 signal, which has the same format as O-P-VECTOR 1, see Figure 10-2. During transmission of the R-P-VECTOR 1, the VCE estimates the FEXT channels from the initializing lines into all vectored lines, and enables the VTU-Os of the vectored lines to cancel FEXT from the initializing lines during the remainder of the initialization of the initializing lines. The time position of the upstream sync symbols and the upstream pilot sequence are assigned by the VCE and are indicated to the VTU-R in the O-SIGNATURE message and by special markers added to the O-P-CHANNEL DISCOVERY V1 signal. + +Furthermore, other optional parameters may be added to the O-P-SIGNATURE message for upstream transmit power reduction during the initial upstream phase (R-P-VECTOR 1). The upstream transmit power reduction can be used to reduce the crosstalk of the R-P-VECTOR 1 signals into non-vectored lines operating in the same binder and provides a flat attenuation of the upstream transmit PSD of R-P-VECTOR 1 in addition to the standard upstream power back-off as defined in [ITU-T G.993.2]. + +NOTE 1 – Parameters *a*, *b* that determine the limiting upstream PSD mask (UPBOMASK, see clause 7.2.1.3.2.2 of [ITU-T G.993.2]) are provided by the operator via the CO-MIB as specified in [ITU-T G.997.1]. The operator may provision or allow for default values of *a*, *b* that are different from those geographic region specific values defined in [ITU-T G.993.2] (e.g., Annexes A.2.3, B.3, and C.2.1.4), and thus allow higher upstream PSDs, since upstream FEXT is reduced through crosstalk cancellation. After UPBO has been applied (during the initialization), the VTU-R may further adjust its transmit PSD (while it remains below the UPBOMASK) during the Showtime by request from the VTU-O, via SRA, as per clause 7.2.1.3.1 of [ITU-T G.993.2], to improve upstream performance (under control of the VCE). The operator may also adjust the applied parameters *a*, *b* via a new initialization. + +At the beginning of the Training phase, the initializing VTU-R will transmit the R-P-VECTOR 1-1 signal, which is the same as R-P-VECTOR 1 and allows the VCE to update the upstream FEXT channel estimates from the initializing lines into the vectored lines, prior to transitioning into the ITU-T G.993.2 Training phase. The VTU-O transmits the O-P-TRAINING V1 signal as a time fill signal while the VTU-R transmits R-P-VECTOR 1-1. + +The initial value of timing advance is assigned by the VTU-O and is communicated in O-SIGNATURE, based on the provisional knowledge on the length of the line. If the timing advance is further re-adjusted during the Training phase, then the FEXT channel estimate in the upstream direction will be updated at the end of the Training phase to account for any resulting change in the FEXT channel (signal R-P-VECTOR 1-2 in Figure 10-1). The VTU-O transmits the O-P-VECTOR 2 signal as a time fill signal while the VTU-R transmits R-P-VECTOR 1-2. + +At the end of the Training phase, the VTU-R transmits R-P-VECTOR 2, which comprises sync symbols modulated by the pilot sequence and regular symbols carrying the SOC. During the transmission of R-P-VECTOR 2, the VCE estimates the FEXT channels from all vectored lines into the initializing lines and vice versa. Finally, at the end of the R-P-VECTOR 2 transmission, the whole FEXT channel matrix, including FEXT coefficients from the initializing lines into the vectored lines and FEXT coefficients from vectored lines into the initializing lines, are estimated by the VCE. At this point the initialization process is complete and the initializing lines become active members of the vectored group. After R-P-VECTOR 2 transmission is complete, the VTU-R enters + +the Channel Analysis and Exchange phase for estimation of the SNR and determination of the bit loading to be used during Showtime. + +During the transmission of R-P-VECTOR 2, the SOC parameters may be set to provide higher speed SOC, necessary to convey clipped error samples from the VTU-R to the VTU-O. Since both VTU-O and VTU-R already passed the Training phase, the number of repetitions in the SOC may be reduced (similarly to [ITU-T G.993.2] during the Channel Analysis and Exchange phase). This will provide a fast backchannel which is necessary for quick estimation of FEXT channels from vectored lines into the initializing line. + +Figures 10-2 and 10-3 show how positions of sync symbols modulated by pilot sequences are aligned during the initialization signals O-P-VECTOR and R-P-VECTOR; the downstream sync symbols of all lines are synchronized in time and upstream sync symbols of all lines are synchronized in time. A time shift between upstream and downstream sync symbols of one or more symbols is set during initialization (see clause 10.3.2.1). + +NOTE 2 – In some implementations, the transmit path of an initializing VTU may change during the Channel Discovery phase. The update of the downstream and upstream FEXT channel allows to capture any related change of the FEXT generated into the vectored lines. Any changes in the transmit path of the analogue front end (AFE) prior to the transmission of O-P-VECTOR 1-1 or R-P-VECTOR 1-1 may increase FEXT generated by the initializing line into vectored lines from the moment of the change until the start of O-P-VECTOR 1-1 or R-P-VECTOR 1-1. Therefore, implementations should minimize the modifications in AFE during the Channel Discovery phase. + +![Figure 10-2: Signal timing diagram showing the alignment of sync symbols and data symbols across multiple lines. The diagram illustrates the timing for Vectored lines (Downstream and Upstream SHOWTIME), the Initializing line (Downstream O-P-VECTOR 1, O-P-VECTOR 1-1, Upstream R-P-VECTOR 1, R-P-VECTOR 1-1, R-P-VECTOR 1-2), and the timing parameters Sync symbol offset and Superframe.](036ceaf207a7b289ca76e160892eb724_img.jpg) + +The diagram illustrates the signal timing for various communication lines. The vertical axis lists the lines: + + +- Vectored lines**: + - Downstream SHOWTIME**: Shows a sequence of symbols where green blocks represent 'Sync symbols carrying pilot sequence' and orange blocks represent 'Data symbols'. + - Upstream SHOWTIME**: Shows a similar sequence of symbols. +- Initializing line**: + - Downstream O-P-VECTOR 1 / O-P-VECTOR 1-1**: Shows green sync symbols. + - Upstream R-P-VECTOR 1 / R-P-VECTOR 1-1 / R-P-VECTOR 1-2**: Shows green sync symbols. + + Key timing parameters are indicated at the bottom: + + +- Sync symbol offset**: The time interval between the start of a sync symbol in the initializing line and the start of a sync symbol in the vectored lines. +- Superframe**: The time interval between the start of one superframe and the start of the next. + + The diagram uses vertical dashed lines to align the start of symbols across different lines. The text 'G.993.5(15)\_F10-2' is in the bottom right corner. + +Figure 10-2: Signal timing diagram showing the alignment of sync symbols and data symbols across multiple lines. The diagram illustrates the timing for Vectored lines (Downstream and Upstream SHOWTIME), the Initializing line (Downstream O-P-VECTOR 1, O-P-VECTOR 1-1, Upstream R-P-VECTOR 1, R-P-VECTOR 1-1, R-P-VECTOR 1-2), and the timing parameters Sync symbol offset and Superframe. + +**Figure 10-2 – Signal timing in the upstream and downstream directions (signals O-P-VECTOR 1 and R-P-VECTOR 1)** + +![Figure 10-3: Signal timing in the upstream and downstream directions. The diagram shows four signal lines: Downstream SHOWTIME, Upstream SHOWTIME, Downstream O-P-VECTOR 2 / O-P-VECTOR 2-1, and Upstream R-P-VECTOR 2. Each line has a sequence of symbols: orange 'Data symbols', green 'Sync symbols carrying pilot sequence', and orange 'Training symbols'. In the downstream direction, the sequence is Data-Sync-Data. In the upstream direction, the sequence is Sync-Data-Sync. The 'O-P-TRAINING 2 symbols active soc with O-IDLE' are shown in the downstream O-P-VECTOR 2 line. The 'R-P-TRAINING 2 symbols active extended soc with R-IDLE and R-ERROR-FEEDBACK' are shown in the upstream R-P-VECTOR 2 line. A 'Sync symbol offset' is indicated by a blue double-headed arrow between the start of a sync symbol in the downstream direction and the start of a sync symbol in the upstream direction. A 'Superframe' is indicated by a blue double-headed arrow spanning the duration of one superframe. The diagram is labeled G.993.5(15)_F10-3.](38cbce07f83fba6d5a7c46605bd5743f_img.jpg) + +Figure 10-3: Signal timing in the upstream and downstream directions. The diagram shows four signal lines: Downstream SHOWTIME, Upstream SHOWTIME, Downstream O-P-VECTOR 2 / O-P-VECTOR 2-1, and Upstream R-P-VECTOR 2. Each line has a sequence of symbols: orange 'Data symbols', green 'Sync symbols carrying pilot sequence', and orange 'Training symbols'. In the downstream direction, the sequence is Data-Sync-Data. In the upstream direction, the sequence is Sync-Data-Sync. The 'O-P-TRAINING 2 symbols active soc with O-IDLE' are shown in the downstream O-P-VECTOR 2 line. The 'R-P-TRAINING 2 symbols active extended soc with R-IDLE and R-ERROR-FEEDBACK' are shown in the upstream R-P-VECTOR 2 line. A 'Sync symbol offset' is indicated by a blue double-headed arrow between the start of a sync symbol in the downstream direction and the start of a sync symbol in the upstream direction. A 'Superframe' is indicated by a blue double-headed arrow spanning the duration of one superframe. The diagram is labeled G.993.5(15)\_F10-3. + +**Figure 10-3 – Signal timing in the upstream and downstream directions (signals O-P-VECTOR 2 and R-P-VECTOR 2)** + +In the following, various phases of the initialization procedure are discussed in more detail. + +## 10.2 ITU-T G.994.1 Handshake phase + +The initialization procedure starts with the ITU-T G.994.1 Handshake phase. During this phase, the VTU-O and the VTU-R shall exchange their enabled vectoring capabilities in addition to the parameters communicated in a regular Handshake phase of [ITU-T G.993.2]. The VTU-O shall support downstream vectoring and may support upstream vectoring. The VTU-R shall support downstream vectoring and shall support upstream vectoring. Based on these capabilities, the final mode of vectored operation (i.e., downstream and upstream vectoring, or downstream only vectoring) is determined during the ITU-T G.994.1 phase of initialization (see Tables 11.68.0.1 and 11.68.10 of [ITU-T G.994.1] and Tables 7-a/b/c/d). + +Before transmission of the MS message, the VTU-O shall verify whether all of the following conditions are TRUE (Note 1): + +- the CO-MIB parameter VECTORMODE\_ENABLE bit 0 is set to 0; +- the Annex X "ITU-T G 993.5-friendly ITU-T G.993.2 operation in the downstream direction" NPar(2) bit is set to ZERO in the CL message or in the CLR message; +- the Annex Y "Full ITU-T G.993.5-friendly ITU-T G.993.2 operation" NPar(2) bit is set to ZERO in the CL message or in the CLR message; +- the "ITU-T G.993.5" SPar(2) bit is set to ZERO in the CL message or in the CLR message. + +If all of the above conditions are TRUE, then the VTU-O shall ensure that the "ITU-T G.993.2" SPar(1) bit is set to ZERO in the last transmitted MS message before the ITU-T G.994.1 clearance procedure (Note 2). Otherwise, the operating mode shall be negotiated solely based on the VTU-O and VTU-R enabled capabilities indicated in the CL and CLR message respectively, as defined in Annex X of [ITU-T G.993.2], Annex Y of [ITU-T G.993.2], and in this clause. + +NOTE 1 – The verification of these conditions is for the VTU-O to ensure that the line will not initialize in "ITU-T G.993.2 mode with neither Annex X nor Annex Y enabled" if this mode is not allowed in the CO-MIB. + +NOTE 2 – This may require the use of the ITU-T G.994.1 extended transaction A:B as defined in Table 14 of [ITU-T G.994.1]. + +The VCE shall force the VTU-O to set the subcarrier spacing and symbol rate in the initializing line to the same value as used in the other vectored lines. + +NOTE 3 – The same symbol rate between all lines of the vectored group is achieved by setting the same ratio between the IDFT size and CE length in samples for upstream and downstream. + +NOTE 4 – During the Handshake phase, the VTU-O selects the value of CE based on the supported values indicated by the VTU-O and the VTU-R. Only the value $CE=5\times N/32$ (where $2\times N$ is the IDFT size) is mandatory. In the absence of other information about the CE capabilities of the VTU-R, this will be the only value that is guaranteed to be supported by a new initializing line. + +**Table 10-1 – VTU-O CL message SPar(2) and NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|--------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5 | This bit shall be set to ONE, if and only if the VTU-O supports ITU-T G.993.5 and ITU-T G.993.5 is allowed via the CO-MIB (i.e., VECTORMODE_ENABLE bit 3 set to 1, see clause 7.3.1.13.9 of [ITU-T G.997.1]). | +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +| Downstream vectoring | This bit shall be set to ONE, indicating the VTU-O supports downstream vectoring. | +| Upstream vectoring | If set to ONE, this bit indicates the VTU-O supports upstream vectoring. If set to ZERO, this bit indicates the VTU-O does not support upstream vectoring. | +| Pilot sequence length multiple of 4 | If set to ONE, this bit indicates the VTU-O supports pilot sequence lengths that are a multiple of 4. If set to ZERO, this bit indicates the VTU-O only supports pilot sequence lengths that are a power of 2. | +| Upstream FDPS | If set to ONE, this bit indicates the VTU-O supports upstream FDPS. If set to ZERO, this bit indicates the VTU-O does not support upstream FDPS. | +| 8192 superframes duration for O-P-VECTOR 1 | If set to ONE, this bit indicates the VTU-O supports extending of O-P-VECTOR 1 duration to 8192 superframes. If set to ZERO, this bit indicates the VTU-O does not support extending of O-P-VECTOR 1 duration to 8192 superframes. | +| Use of O-P-VECTOR 1 flag tones only |

If set to ONE, this bit indicates the VTU-O supports the use of O-P-VECTOR 1 flag tones only (see clause 10.3.3.1). If set to ZERO, this bit indicates that the VTU-O does not support use of O-P-VECTOR 1 flag tones only.

If bit "8192 superframes duration for O-P-VECTOR 1" is set to ZERO, then bit "Use of O-P-VECTOR 1 flag tones" shall also be set to ZERO.

| + +**Table 10-2 – VTU-O MS message SPar(2) and NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bits | +|--------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5 | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that both VTUs shall enter ITU-T G.993.5 initialization. | +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +| Downstream vectoring | This bit shall be set to ONE, indicating downstream vectoring. | +| Upstream vectoring | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates upstream vectoring is enabled. If set to ZERO, this bit indicates upstream vectoring is disabled. | +| Pilot sequence length multiple of 4 | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "pilot sequence length multiple of 4" is enabled. If set to ZERO, this bit indicates only pilot sequence lengths that are a power of 2 are enabled. | +| Upstream FDPS | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that upstream FDPS is enabled. If set to ZERO, this bit indicates that upstream FDPS is disabled. | +| 8192 superframes duration for O-P-VECTOR 1 | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "8192 superframes duration for O-P-VECTOR 1" is enabled. If set to ZERO, this bit indicates that "8192 superframes duration for O-P-VECTOR 1" is disabled. | +| Use of O-P-VECTOR 1 flag tones only | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "Use of O-P-VECTOR 1 flag tones only" is enabled. If set to ZERO, this bit indicates that "Use of O-P-VECTOR 1 flag tones only" is disabled. | + +**Table 10-3 – VTU-R CLR message SPar(2) and NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bits | +|--------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5 | This bit shall be set to ONE, if and only if the VTU-R supports ITU-T G.993.5. | +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +| Downstream vectoring | This bit shall be set to ONE, indicating the VTU-R supports downstream vectoring. | +| Upstream vectoring | This bit shall be set to ONE, indicating the VTU-R supports upstream vectoring. | +| Pilot sequence length multiple of 4 | If set to ONE, this bit indicates the VTU-R supports pilot sequence lengths that are a multiple of 4. If set to ZERO, this bit indicates the VTU-R only supports pilot sequence lengths that are a power of 2. | +| Upstream FDPS | If set to ONE, this bit indicates the VTU-R supports upstream FDPS. If set to ZERO, this bit indicates the VTU-R does not support upstream FDPS. | +| 8192 superframes duration for O-P-VECTOR 1 | If set to ONE, this bit indicates the VTU-R supports extending of O-P-VECTOR 1 duration to 8192 superframes. If set to ZERO, this bit indicates the VTU-R does not support extending of O-P-VECTOR 1 duration to 8 192 superframes. | +| Use of O-P-VECTOR 1 flag tones only |

If set to ONE, this bit indicates the VTU-R supports the use of O-P-VECTOR 1 flag tones only (see clause 10.3.3.1). If set to ZERO, this bit indicates that the VTU-R does not support use of O-P-VECTOR 1 flag tones only.

If bit "8192 superframes duration for O-P-VECTOR 1" is set to ZERO, then bit "Use of O-P-VECTOR 1 flag tones" shall also be set to ZERO.

| + +**Table 10-4 – VTU-R MS message SPar(2) and NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bits | +|--------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T G.993.5 | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that both VTUs shall enter ITU-T G.993.5 initialization. | +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +| Downstream vectoring | This bit shall be set to ONE, indicating downstream vectoring. | +| Upstream vectoring | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates upstream vectoring is enabled. If set to ZERO, this bit indicates upstream vectoring is disabled. | +| Pilot sequence length multiple of 4 | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "pilot sequence length multiple of 4" is enabled. If set to ZERO, this bit indicates only pilot sequence lengths that are a power of 2 are enabled. | +| Upstream FDPS | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that upstream FDPS is enabled. If set to ZERO, this bit indicates that upstream FDPS is disabled. | +| 8192 superframes duration for O-P-VECTOR 1 | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "8192 superframes duration for O-P-VECTOR 1" is enabled. If set to ZERO, this bit indicates that "8192 superframes duration for O-P-VECTOR 1" is disabled. | +| Use of O-P-VECTOR 1 flag tones only | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message. If set to ONE, this bit indicates that "Use of O-P-VECTOR 1 flag tones only" is enabled. If set to ZERO, this bit indicates that "Use of O-P-VECTOR 1 flag tones only" is disabled. | + +### 10.2.1 Avoidance of false initialization in crosstalk environment + +The functionality defined in this clause prevents one VTU-O from establishing communication with two VTU-Rs. Such communication would lead to two VTU-Rs sending the same upstream pilot sequence, with potential negative impact on the VCE learning the upstream channel matrix. + +Support of this functionality is optional for the VTU-O and is optional for the VTU-R. If supported, the functionality shall be implemented as defined in this clause. + +In the ITU-T G.994.1 identification field, two parameters are defined for the exchange of transceiver IDs (see [ITU-T G.994.1] Table 9.14, Tables 9.14.1.x, and Tables 9.14.2.x): + +- network side transceiver ID SPar(2) with associated 30-bit NPar(3) parameter; +- remote side transceiver ID SPar(2) with associated 30-bit NPar(3) parameter. + +The network side transceiver ID is the VTU-O ID. The VTU-O ID shall be generated by the VTU-O. + +The remote side transceiver ID is the VTU-R ID. The VTU-R ID shall be generated by the VTU-R. + +The 30 bit VTU ID shall consist of two parts: + +- a first part (the MSBs) derived from the serial number and vendor ID; + +– a second part (the LSBs) using a random number generator. + +The first part has length 16 bits and shall be calculated as the 16-bit high-level data link control (HDLC) frame check sequence (FCS), as specified in clause 6.4.3 of [ITU-T G.997.1], of the VTU vendor ID and the VTU serial number. + +The FCS shall be calculated over all bits of the VTU vendor ID followed by the VTU serial number. + +The FCS shall be calculated starting with bit 1 (LSB) of octet 1. The octets shall follow each other in ascending numerical order. Within an octet, the bits shall follow each other in ascending numerical order. + +The register used to calculate the CRC shall be initialized to the value $\text{FFFF}_{16}$ . + +The VTU vendor ID shall consist of the T.35 country code (2 octets) followed by the provider code (4 octets), as indicated in the Vendor ID information block during the ITU-T G.994.1 Handshake phase of initialization (see Table 7 of [ITU-T G.994.1]). + +NOTE – This is excluding the "Vendor-specific information" of the Vendor ID information block. + +The VTU-O serial number shall be the G.997.1 X digital subscriber line transceiver unit at the central office (XTU-C) serial number (see clause 7.4.7 of [ITU-T G.997.1]). + +The VTU-R serial number shall be the equipment serial number that is part of the G.997.1 X digital subscriber line transceiver unit at the remote end (XTU-R) serial number (see clause 7.4.8 of [ITU-T G.997.1]). + +NOTE – This is excluding the equipment model and the equipment firmware version that are also part of the G.997.1 XTU-R serial number. + +The second part has length 14 bits and shall be generated by the VTU by means of a vendor discretionary random number generator. The randomly generated number shall change from one ITU-T G.994.1 session to the next. + +If a transceiver sends any of the messages listed in Table 10-5, that message shall include the transceiver IDs as listed in Table 10-5. The "M" denotes "mandatory", the "CO" denotes "conditionally optional", and the "CM" denotes "conditionally mandatory", with the condition being that the far-end transceiver ID is included if and only if it has been received in a previous message during the same ITU-T G.994.1 session. + +**Table 10-5 – Transceiver IDs included in ITU-T G.994.1 and initialization messages** + +| | VTU-O ID | VTU-R ID | +|---------------|----------|----------| +| CLR | – | M | +| CL | M | CO | +| MP | CM | M | +| MS from VTU-O | M | CM | +| MS from VTU-R | CM | M | +| O-SIGNATURE | – | CM | + +If the VTU-R receives a CL or MS message that contains a VTU-R ID different from the VTU-R ID sent in the CLR message, then the VTU-R shall respond with a NAK-CD message followed by the ITU-T G.994.1 session teardown procedure specified in clause 11.3 of [ITU-T G.994.1]. + +If the VTU-O receives an MP or MS message that contains a VTU-O ID different from the VTU-O ID sent in the CL message, then the VTU-O shall respond with a NAK-CD message followed by the ITU-T G.994.1 session teardown procedure specified in clause 11.3 of [ITU-T G.994.1]. + +If the VTU-R receives an O-SIGNATURE message that contains a VTU-R ID different from the VTU-R ID sent in the CLR message, then the VTU-R shall return to the R-SILENT state. + +If the VTU-R receives an O-SIGNATURE message that contains a VTU-R ID equal to the VTU-R ID sent in the CLR message, then communication has been established only among transceivers with acknowledged transceiver IDs, and initialization shall proceed as defined in clause 10.3. + +NOTE 1 – The VTU-R transceiver ID is included in O-SIGNATURE to avoid false detection in the case a VTU-O decides to interrupt the communication during O-P-VECTOR-1. + +NOTE 2 – Even if communication has been established only among transceivers with acknowledged transceiver IDs, the resulting communication may be over a crosstalk path (i.e., not the direct path). If this should occur, the integrity of the upstream channel matrix is not compromised during the R-P-VECTOR 1 phase of channel discovery, since the VCE will see unique upstream pilot sequences on each initializing line. + +The VTU-O shall ensure that the ITU-T G.994.1 message sequence allows both the VTU-O and the VTU-R to get acknowledgement of their transceiver ID during the ITU-T G.994.1 session. Table 10-6 lists examples of such ITU-T G.994.1 message sequences. + +**Table 10-6 – Examples of ITU-T G.994.1 transaction sequences** + +| Example nr | ITU-T G.994.1 message sequence | +|------------|------------------------------------------------------------------------------------------------| +| 1 | Transaction C: CLR → CL → ACK(1);
Transaction D: MP → MS → ACK(1). | +| 2 | Transaction C: CLR → CL → ACK(1);
Extended transaction A:B: MS → REQ-MR → MR → MS → ACK(1). | +| 3 | Transaction C: CLR → CL (including the VTU-R ID) → ACK(1);
Transaction A: MS → ACK(1). | +| 4 | Transaction C: CLR → CL (including the VTU-R ID) → ACK(1);
Transaction B: MR → MS → ACK(1). | + +## 10.3 Channel Discovery phase + +### 10.3.1 Overview + +The Handshake phase shall be followed by the Channel Discovery phase. If both downstream and upstream vectoring are disabled after the ITU-T G.994.1 phase, then all vectoring-related parts of the initialization shall be skipped and the Channel Discovery phase shall be performed as defined in [ITU-T G.993.2]. + +If downstream vectoring or upstream vectoring is enabled, then the Channel Discovery phase is a modified version of the ITU-T G.993.2 Channel Discovery phase. Figures 10-4 and 10-5 highlight the signals added and the signals/messages modified in the ITU-T G.993.2 Channel Discovery phase for ITU-T G.993.5 transceivers. Non-highlighted signals and messages shall be as defined in [ITU-T G.993.2]. + +![Sequence diagram showing the early stages of the Channel Discovery phase between Downstream and Upstream entities. The diagram is divided into two vertical timelines. The Downstream timeline includes SOC messages (O-IDLE, O-SIGNATURE, O-IDLE) and ITU-T G.994.1 handshake signals (O-P-QUIET 1, O-P-VECTOR 1, O-P-CHANNEL-DISCOVERY V1, O-P-SYNCHRO V1, O-P-CHANNEL-DISCOVERY 1, O-P-SYNCHRO 1). The Upstream timeline includes ITU-T G.994.1 handshake signals (R-P-QUIET 1, R-P-VECTOR 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1) and SOC messages (R-IDLE, R-MSG 1). Vertical arrows on the far left and right are labeled 'CHANNEL DISCOVERY phase (VTU-O)' and 'CHANNEL DISCOVERY phase (VTU-R)' respectively. Dashed horizontal lines separate the different message stages.](89f8aefc01866631793087542316cef2_img.jpg) + +Sequence diagram showing the early stages of the Channel Discovery phase between Downstream and Upstream entities. The diagram is divided into two vertical timelines. The Downstream timeline includes SOC messages (O-IDLE, O-SIGNATURE, O-IDLE) and ITU-T G.994.1 handshake signals (O-P-QUIET 1, O-P-VECTOR 1, O-P-CHANNEL-DISCOVERY V1, O-P-SYNCHRO V1, O-P-CHANNEL-DISCOVERY 1, O-P-SYNCHRO 1). The Upstream timeline includes ITU-T G.994.1 handshake signals (R-P-QUIET 1, R-P-VECTOR 1, R-P-CHANNEL-DISCOVERY 1, R-P-SYNCHRO 1) and SOC messages (R-IDLE, R-MSG 1). Vertical arrows on the far left and right are labeled 'CHANNEL DISCOVERY phase (VTU-O)' and 'CHANNEL DISCOVERY phase (VTU-R)' respectively. Dashed horizontal lines separate the different message stages. + +G.993.5(15)\_F10-4 + +Figure 10-4 – Early stages of the Channel Discovery phase + +![Sequence diagram showing the last stages of the Channel Discovery phase between Downstream (VTU-O) and Upstream (VTU-R) units. The diagram is divided into four columns: Downstream SOC messages, Downstream Signals, Upstream Signals, and Upstream SOC messages. The sequence starts with Downstream sending O-P-SYNCHRO 1, followed by a shaded block containing O-P-QUIET 2 and O-P-PILOT 1. Then O-P-PERIODIC 1 and O-P-SYNCHRO 2 are sent. The Downstream SOC messages column contains O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, and O-IDLE. A large yellow block labeled O-P-CHANNEL-DISCOVERY 2 spans from the O-P-SYNCHRO 2 signal down to just before the O-P-SYNCHRO 3 signal. Upstream signals include R-P-SYNCHRO 1, a shaded block containing R-P-LINEPROBE, R-P-PERIODIC 1, R-P-SYNCHRO 2, R-P-CHANNEL-DISCOVERY 2, and R-P-SYNCHRO 3. Upstream SOC messages include R-IDLE, R-UPDATE, R-IDLE, R-PRM, and R-IDLE. Vertical arrows on the sides indicate the CHANNEL DISCOVERY phase (VTU-O) and CHANNEL DISCOVERY phase (VTU-R).](a2251e3bbfcd726b68cc50b091e53b02_img.jpg) + +Sequence diagram showing the last stages of the Channel Discovery phase between Downstream (VTU-O) and Upstream (VTU-R) units. The diagram is divided into four columns: Downstream SOC messages, Downstream Signals, Upstream Signals, and Upstream SOC messages. The sequence starts with Downstream sending O-P-SYNCHRO 1, followed by a shaded block containing O-P-QUIET 2 and O-P-PILOT 1. Then O-P-PERIODIC 1 and O-P-SYNCHRO 2 are sent. The Downstream SOC messages column contains O-IDLE, O-UPDATE, O-IDLE, O-PRM, O-IDLE, O-ACK, and O-IDLE. A large yellow block labeled O-P-CHANNEL-DISCOVERY 2 spans from the O-P-SYNCHRO 2 signal down to just before the O-P-SYNCHRO 3 signal. Upstream signals include R-P-SYNCHRO 1, a shaded block containing R-P-LINEPROBE, R-P-PERIODIC 1, R-P-SYNCHRO 2, R-P-CHANNEL-DISCOVERY 2, and R-P-SYNCHRO 3. Upstream SOC messages include R-IDLE, R-UPDATE, R-IDLE, R-PRM, and R-IDLE. Vertical arrows on the sides indicate the CHANNEL DISCOVERY phase (VTU-O) and CHANNEL DISCOVERY phase (VTU-R). + +G.993.5(15)\_F10-5 + +Figure 10-5 – Last stages of the Channel Discovery phase + +### 10.3.2 Modified SOC messages sent during Channel Discovery phase + +#### 10.3.2.1 O-SIGNATURE + +The O-SIGNATURE message which is transmitted during O-P-CHANNEL DISCOVERY V1 and O-P-CHANNEL DISCOVERY 1 contains an ITU-T G.993.5 parameter field A and an ITU-T G.993.5 parameter field B. The ITU-T G.993.5 parameter field A is of variable length and contains several parameters needed for the FEXT cancellation operation, as shown in Table 10-7. The ITU-T G.993.5 parameter field B includes parameters needed to define the upstream FDPS, as shown in Table 10-9. + +**Table 10-7 – ITU-T G.993.5 parameter field A in message O-SIGNATURE** + +| Field | Content of field | Format | +|-------|-----------------------------------------------------------|---------------------------------------| +| 1 | ITU-T G.993.5 parameter field A length | 1 byte | +| 2 | Vectored downstream bands | Bands descriptor | +| 3 | Upstream pilot sequence length | 2 bytes | +| 4 | Upstream pilot sequence | $\lceil N_{pilot\_us}/8 \rceil$ bytes | +| 5 | Upstream sync symbol offset | 1 bytes | +| 6 | Upstream R-P-VECTOR 1 PSD cutback | 1 bytes | +| 7 | Downstream sync symbol counter modulo value ( $N_{SSC}$ ) | 2 bytes | +| 8 | VCE vendor ID and version number | 10 bytes | +| 9 | VTU-R ID | 4 bytes | + +Field #1, "ITU-T G.993.5 parameter field A length", indicates the length of the ITU-T G.993.5 parameter field A in bytes, excluding the ITU-T G.993.5 parameter field A length field. All fields shown in Table 10-7 shall be included in the ITU-T G.993.5 parameter field A in the O-SIGNATURE message. The field shall be represented as an unsigned integer. + +Field #2, "Vectored downstream bands", defines frequency bands that are allocated by the VCE for vectoring in the downstream direction. This field shall be formatted as "Bands descriptor" (see Table 12-18 of [ITU-T G.993.2]). No more than eight bands shall be specified. The subcarrier indices that define band edges shall comply with the requirements in clause 7.2.2. + +Field #3, "Upstream pilot sequence length", defines the length of the upstream pilot sequence ( $N_{pilot\_us}$ , see clause 7.3.3) in bits. If the "pilot sequence length multiple of 4" is enabled (see clause 10.2), then valid values are all multiples of 4 in the range from 8 to 512. Otherwise, valid values are powers of 2 in the range from 8 to 512. The field shall be represented as an unsigned integer representing the length of the sequence. + +Field #4, "Upstream pilot sequence", defines the pilot sequence allocated by the VCE to be modulated on the sync symbols contained in the R-P-VECTOR signals. The format is a binary string of length $N_{pilot\_us}$ bits (see clause 7.3.3), with the first bit of the pilot sequence (bit index 0) mapped to the LSB of the first byte in this field and the last bit of the pilot sequence (bit index $N_{pilot\_us} - 1$ ) mapped on the MSB of the last byte of the field. The length of the field shall be derived from field #3 as $\lceil N_{pilot\_us}/8 \rceil$ . If $N_{pilot\_us}$ is not a multiple of 8 then the last octet of this field shall have the 4 MSBs set to 0. + +Field #5, "Upstream sync symbol offset", defines the time offset set by the VCE (expressed as a number of symbols) between the downstream sync symbol and the upstream sync symbol. The field shall be represented as an integer in 2's complement representation with valid range from -127 to +127, except 0, where negative offset indicates that the upstream sync symbols are delayed relatively to the downstream sync symbols. + +NOTE – The value of 0 is excluded from the valid range of offsets between sync symbols in upstream and downstream directions on the U-interface because it may influence vendor specific processing done on the sync symbols due to reduced randomness of the echo signal. + +Field #6, "Upstream R-P-VECTOR 1 PSD cutback", defines a flat attenuation set by the VCE for the upstream transmit PSD of R-P-VECTOR 1 in addition to the upstream power back-off. It is coded in steps of 0.1 dB in a 0 dB to 25.5 dB range. The field shall be represented as an unsigned integer in the 0 (0 dB) to 255 (25.5 dB) range. + +Field #7 "Downstream sync symbol counter modulo value (N\_SSC)", defines the modulo value to be used for maintaining the downstream sync symbols counter during Showtime. If the "pilot sequence length multiple of 4" is enabled (see clause 10.2), then this field is coded as an unsigned integer representing the value of $N\_SSC$ , with a single valid value being the lowest $(2^n \times N_{pilot\_ds}) \geq 1024$ , where $n$ is an integer. Otherwise, it is coded as an unsigned integer with a single valid value if $N\_SSC$ equal to 1024. + +NOTE – If $N\_SSC$ is an integer multiple of the downstream pilot sequence length, then the pilot sequence bit index may be derived from the downstream sync symbol counter through a modulo operation. + +Field #8 "VCE vendor ID and version number" defines the VCE vendor ID and version number. It consists of 10 bytes, with definition and format as depicted in Table 10-8. + +Field #9 "VTU-R ID", contains the 30-bit transceiver ID of the VTU-R (with the two MSBs of this field set to 002). If the VTU-O has received the VTU-R ID during the last previous ITU-T G.994.1 session, then this field shall contain that VTU-R ID, otherwise this field shall be set to 0000000016. + +**Table 10-8 – VCE Vendor ID information block (10 bytes)** + +| | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ITU-T T.35 country code (2 bytes – Note 1) | +| Provider code (vendor identification) (4 bytes – Note 2) | +| Vendor specific version number (4 bytes) | +|

NOTE 1 – If the bits in the first octet are not all set to binary ONE, the bits in the second octet shall be set to binary ZERO by the transmitter and ignored by the receiver. The only purpose of the country code is to identify the country of registry of the provider code.

NOTE 2 – Specification of the coding and order of transmission of this field is the responsibility of the regional standards body allocating the provider code. See Appendix II of [ITU-T G.994.1] for provider code contact information.

| + +**Table 10-9 – ITU-T G.993.5 parameter field B in message O-SIGNATURE** + +| Field | Content of field | Format | +|-------|----------------------------------------|--------------------------| +| 1 | ITU-T G.993.5 parameter field B length | 2 bytes | +| 2 | Upstream FDPS | Upstream FDPS descriptor | + +Field #1, "ITU-T G.993.5 parameter field B length", indicates the length of the ITU-T G.993.5 parameter field B in bytes, excluding the ITU-T G.993.5 parameter field B length field. If none of the fields following field #1 is included in the ITU-T G.993.5 parameter field B, then the ITU-T G.993.5 parameter field B shall be two bytes long with value 000016. The field shall be represented as an unsigned integer. + +Field #2, "Upstream FDPS", defines the additional independent pilot sequences allocated by the VCE and how the upstream pilot sequences to be modulated on the sync symbols contained in the R-P-VECTOR signals are derived. This field shall be formatted as "upstream FDPS descriptor" (see Table 10-10). If upstream FDPS is disabled through ITU-T G.994.1, then the upstream FDPS descriptor shall not be included in the ITU-T G.993.5 parameter field B. + +**Table 10-10 – Upstream FDPS descriptor** + +| Field | Content of field | Format | +|-------|--------------------------------------------------------------------------------|------------------------------------| +| 1 | Index of the associated independent pilot sequence | 3 bytes | +| 2 | Sign of the sequence relatively to the associated independent sequence | 1 byte | +| 3 | Cyclical shift of the sequence relative to the associated independent sequence | 3 bytes | +| 4 | Number of additional independent pilot sequences ( Naips ) | 1 byte | +| 5 | Bits of independent pilot sequence #1 | $\lceil Npilot\_us/8 \rceil$ bytes | +| | ... | ... | +| | Bits of independent pilot sequence # Naips | $\lceil Npilot\_us/8 \rceil$ bytes | + +Field #1, "Index of the associated independent pilot sequence", is a 24-bit field divided into eight 3-bit subfields. The first subfield (in the 3 LSB) represents the index of the independent pilot sequence to be the pilot sequence #0, the eighth subfield (in the 3 MSB) represents the index of the independent pilot sequence to be the pilot sequence #7. The index shall be represented as a 3-bit unsigned integer. + +Field #2, "Sign of the sequence relatively to the associated independent pilot sequence", is an 8-bit bitmap, where a 0 indicates that the pilot sequence with the given index has the same sign as the associated independent pilot sequence and a 1 indicates that it has an inverted sign relative to the associated independent pilot sequence. The LSB indicates whether the sign inversion shall be applied to pilot sequence #0, the MSB indicates whether the sign inversion shall be applied to pilot sequence #7. + +Field #3, "Cyclical shift of the sequence relative to the associated independent pilot sequence", is a 24-bit field divided into eight 3-bit subfields. The first subfield (in the 3 LSB) represents the cyclic shift of pilot sequence #0 relative to the associated independent pilot sequence, the eighth subfield (in the 3 MSB) represents the cyclic shift of pilot sequence #7 relative to the associated independent pilot sequence. The value of the subfield is the actual cyclic shift (*CyS*) represented as unsigned integer with values 0 to 7, where: + +Pilot sequence bit [*i*] = + +Associated independent pilot sequence bit $[(i + CyS \times Npilot\_us / 8) \text{ MOD } Npilot\_us]$ . + +If *Npilot\_us* is an odd multiple of 4, then the value of *CyS* shall be even. + +Field #4, "Number of additional independent pilot sequences (*Naips*)" is a 1-byte field representing the number of additional independent pilot sequences included in the Upstream FDPS descriptor. Valid *Naips* values are 0 to 7. + +Field #5, "Bits of additional independent pilot sequences", defines the bits of the *Naips* additional independent pilot sequences (i.e., independent pilot sequence #1 to independent pilot sequence #*Naips*) allocated by the VCE to be modulated on the upstream sync symbols. Each sequence is *Npilot\_us* bits long (see clause 7.3.3). Each sequence is mapped into $\lceil Npilot\_us/8 \rceil$ bytes as defined for field #4 in Table 10-7 (the last byte can be incomplete). The total length of the field shall be *Naips* $\times \lceil Npilot\_us/8 \rceil$ bytes. Bits of the independent pilot sequence #0 are communicated in the "Upstream pilot sequence" field #4 of the ITU-T G.993.5 parameter field A. + +#### 10.3.2.2 R-MSG1 + +The R-MSG1 message (defined in Table 12-24 of [ITU-T G.993.2]), which is transmitted during R-P-CHANNEL DISCOVERY 1, contains an ITU-T G.993.5 parameter field. The ITU-T G.993.5 + +parameter field contains several parameters needed for FEXT cancellation operation, as shown in Table 10-11. + +**Table 10-11 – ITU-T G.993.5 parameter field in message R-MSG1** + +| Field | Field name | Format | +|-------|----------------------------------------------------------|-----------------------| +| 1 | ITU-T G.993.5 parameter field length | 1 byte | +| 2 | Maximum number of FEXT estimation symbols per superframe | 1 byte | +| 3 | Support of optional backchannel control parameters | Parameters descriptor | + +Field #1, "ITU-T G.993.5 parameter field length", indicates the length of the vectoring descriptor field in bytes, excluding the ITU-T G.993.5 parameter field length field. All fields shown in Table 10-11 shall be included in the R-MSG1 message. The field shall be represented as an unsigned integer. + +Field #2, "Maximum number of FEXT estimation symbols per superframe", defines the maximum number ( $K_{max}$ ) of symbols in the superframe for which the VTU-R supports error sample reporting (see clause 10.4.2.1). The field shall be formatted as an unsigned integer with valid $K_{max}$ values = 1, 2, 4, 6, and 8. The VTU-R shall support the value $K_{max} = 1$ . Other values of $K_{max}$ are optional. + +Field #3, "Support of optional backchannel control parameters", indicate the optional values of control parameters supported by the VTU-R, as described in Table 10-12. + +**Table 10-12 – Optional backchannel control parameters descriptor** + +| Bit | Description | +|-----|------------------------------------------------------------------------------| +| 0 | Set to 1 if $F\_block = 32$ with $padding = 0$ is supported and 0 otherwise. | +| 1 | Set to 1 if $F\_block = 32$ with $padding = 1$ is supported and 0 otherwise. | +| 2 | Set to 1 if $F\_sub = 1$ is supported and 0 otherwise. | +| 3 | Set to 1 if $L\_w = 9$ is supported and 0 otherwise. | +| 4 | Set to 1 if $L\_w = 10$ is supported and 0 otherwise. | +| 5 | Set to 1 if $L\_w = 11$ is supported and 0 otherwise. | +| 6 | Set to 1 if $L\_w = 12$ is supported and 0 otherwise. | +| 7 | Reserved by ITU-T and shall be set to 0. | + +### 10.3.3 Vectoring-specific VTU-O signals transmitted during the Channel Discovery phase + +#### 10.3.3.1 O-P-VECTOR 1 + +The O-P-QUIET 1 signal shall be followed by the O-P-VECTOR 1 signal. + +The O-P-VECTOR 1 signal shall consist of sync symbols and quiet symbols only. sync symbols shall be transmitted at each downstream sync symbol position (as defined in clause 6.2.3). Quiet symbols shall be transmitted at all other symbol positions (see Figure 10-2). + +The O-P-VECTOR 1 sync symbols shall be generated as described in clause 10.5 of [ITU-T G.993.2]. These sync symbols shall modulate a pilot sequence. The pilot sequence is a repetitive sequence, as defined in clause 6.2.3, assigned to the initializing line by the VCE. Each probe tone of a sync symbol from the SUPPORTEDCARRIERs set with a pilot sequence bit equal to ZERO shall modulate a 00 constellation point, and with a pilot sequence bit equal to ONE shall modulate a 11 constellation point. The 00 and 11 constellation points shall be per the 4-QAM constellation defined in clause 10.3.3.2.1 of [ITU-T G.993.2]. The constellation points on + +subcarriers shall then be rotated by the quadrant scrambler defined in clause 12.3.6.2 of [ITU-T G.993.2]. + +If the bit "8192 superframes duration for O-P-VECTOR 1" is disabled in the ITU-T G.994.1 phase (see clause 10.2), then for sync symbols, the transmit PSD of all subcarriers shall be equal to CDPSDDs. + +If the bit "8192 superframes duration for O-P-VECTOR 1" is enabled and the bit "Use of O-P-VECTOR 1 flag tones only" is disabled in the ITU-T G.994.1 phase (see clause 10.2), then for sync symbols, the transmit PSD of all subcarriers shall be equal to CDPSDDs. + +If both the bit "8192 superframes duration for O-P-VECTOR 1" and the bit "Use of O-P-VECTOR 1 flag tones only" are enabled in the ITU-T G.994.1 phase (see clause 10.2), then for sync symbols, the transmit PSD of all subcarriers shall be equal to CDPSDDs, except that for the first N sync symbols, the transmit power of all probe tones shall be 0 (with N a value determined by the VCE, in the range from 0 to 2048 sync symbols). + +NOTE 1 – A way to identify the value of N is described in Appendix II. + +The duration of O-P-VECTOR 1 is vendor discretionary, but shall be minimum $4 \times 257$ symbols and maximum $M \times 1024 \times 257$ symbols. Valid values for $M$ are 1 and 8. Support of $M=1$ is mandatory for the VTU-O and the VTU-R. Support of $M=8$ is optional for both the VTU-O and the VTU-R. If the bit "8192 superframes duration for O-P-VECTOR 1" is enabled in the [ITU-T G.994.1] phase (see clause 10.2), then $M=8$ . Otherwise, $M=1$ . + +NOTE 2 – The O-P-VECTOR 1 signal should be shortened by the VCE to accelerate full system start-up. + +NOTE 3 – Appendix II provides examples of VCE control of the initialization process in the activation of multiple lines in the vectored group. Clause II.2 describes such VCE control using the "8192 superframes duration for O-P-VECTOR 1" capability in handling two groups of lines. Clause II.3 describes such VCE control using handshake capabilities. + +During transmission of the O-P-VECTOR 1 signal, the SOC is in its inactive state. + +During transmission of the O-P-VECTOR 1 signal, the VCE estimates the downstream FEXT channels from the initializing lines into the vectored lines based on the reported clipped error samples from the VTU-Rs of the vectored lines. From this point on, FEXT cancellation matrices are established in the VTU-Os for all vectored lines in the downstream direction and FEXT from the initializing line into vectored lines is cancelled. + +The O-P-VECTOR 1 signal shall be followed by the O-P-CHANNEL DISCOVERY V1 signal, which determines the actual duration of O-P-VECTOR 1. The start time of O-P-CHANNEL DISCOVERY V1 transmission is determined by the VCE. + +#### 10.3.3.2 O-P-CHANNEL DISCOVERY V1 + +The O-P-CHANNEL DISCOVERY V1 signal shall be identical to the O-P-CHANNEL DISCOVERY 1 signal defined in clause 12.3.3.3.1 of [ITU-T G.993.2], with the addition of markers to indicate the downstream sync symbol positions and upstream pilot sequence positions (as defined in clause 10.3.3.5). + +The addition of markers consists of modulating on all symbols the subcarriers with index $10n+9$ with constellation point 00 or 11, as defined in clause 10.3.3.5. + +During transmission of O-P-CHANNEL DISCOVERY V1, the SOC is in its active state, sending O-IDLE for a period of at least 1500 symbols and no more than 2000 symbols and followed by the O-SIGNATURE message, as defined in clause 12.3.3.2.1 of [ITU-T G.992.3] and clause 10.3.2.1. The O-SIGNATURE shall be sent in auto-repeat mode, the same as O-SIGNATURE in [ITU-T G.993.2]. + +The O-P-CHANNEL DISCOVERY V1 signal shall be followed by the O-P-SYNCHRO V1 signal, which determines the actual duration of the O-P-CHANNEL DISCOVERY V1. The start time of O-P-SYNCHRO V1 transmission is determined by the VCE. + +#### 10.3.3.3 O-P-SYNCHRO V1 + +The O-P-SYNCHRO V1 signal shall be identical to the O-P-SYNCHRO 1 signal defined in clause 12.3.3.3.1 of [ITU-T G.993.2]. + +During transmission of O-P-SYNCHRO V1, the SOC is in its inactive state. + +With the VTU-O transmitting the O-P-SYNCHRO V1 signal, the VCE notifies the VTU-R that the upstream FEXT channel estimation is completed, and that the VTU-R shall end the transmission of R-P-VECTOR 1. The VTU-O shall transmit O-P-SYNCHRO V1 only after VCE detects that R-P-VECTOR 1 is transmitted during at least $4 \times 257$ symbols. + +The O-P-SYNCHRO V1 signal shall be followed by the O-P-CHANNEL DISCOVERY 1 signal. + +#### 10.3.3.4 O-P-CHANNEL DISCOVERY 1 and O-P-CHANNEL DISCOVERY 2 + +These signals shall be identical to the O-P-CHANNEL DISCOVERY 1 and O-P-CHANNEL DISCOVERY 2 signals defined in clause 12.3.3.3.1 of [ITU-T G.993.2], respectively, with the addition of markers to indicate the downstream sync symbol positions and upstream pilot sequence position (as defined in clause 10.3.3.5). The pattern of markers shall be continued taking into account all downstream sync symbol positions from the beginning of O-P-CHANNEL DISCOVERY V1. + +NOTE – It is beneficial if O-P-SYNCHRO 1 and O-P-SYNCHRO 3 signals are not transmitted at downstream sync symbol positions. + +During the O-P-CHANNEL DISCOVERY 1, the VTU-O shall transmit O-IDLE; the transmission shall start after the last symbol of O-P-SYNCHRO V1. + +#### 10.3.3.5 Downstream sync symbol and upstream pilot sequence markers + +To indicate the time position of the downstream sync symbols and the required by VCE time position of the upstream sync symbols and upstream pilot sequence, the VTU-O shall modulate the subset of subcarriers with indices $10n+9$ with either the constellation point (00) or the constellation point (11) of the 4-QAM constellation, before the quadrant scrambler. All those subcarriers shall be modulated with the same information per symbol, i.e., either 00 or 11. Symbols whose subcarriers are modulated with either 00 or 11 are further noted in this clause as either ZERO or ONE symbols, respectively. A sequence of ZERO and ONE symbols forms a pattern that is used to indicate time positions of the sync symbol and pilot sequence. + +Figure 10-6 shows the symbol modulation pattern. The time position of a downstream sync symbol shall be indicated by eight consecutive ONE symbols, starting at the time position of the downstream sync symbol of the vectored lines. The VTU-R shall derive the time position of the upstream sync symbol from the indicated time position of the downstream sync symbol by applying the offset between upstream and downstream sync symbols, which is communicated to the VTU-R in O-SIGNATURE. + +The time position of the upstream pilot sequence shall be indicated by a 20-symbol pattern following the eight consecutive ONEs pattern, see Figure 10-6. This pattern of ONE and ZERO symbols shall represent the bit index of the upstream pilot sequence that modulates subcarriers of the upstream sync symbol associated (through the value of the offset) with this downstream sync symbol that precedes the mentioned 20-symbol pattern (as shown in Figure 10-6). + +The bit index of the upstream pilot sequence shall be represented as an unsigned integer, and each bit of this integer is represented by two consecutive symbols of the pattern, with symbols 7 and 8 in Figure 10-6 representing the LSB. A bit value 0 shall be represented by a ZERO symbol followed + +by a ONE symbol. A bit value 1 shall be represented by a ONE symbol followed by a ZERO symbol. All the symbols after the 20-symbol pattern shall be ZERO symbols until the time position of the next downstream sync symbol. + +NOTE – With this technique, the upstream sync symbol time position can be detected by looking for the pattern of eight consecutive ONEs and the bit index in the pilot sequence by decoding the 20 following symbols. This allows a quick detection of the time position of the upstream pilot sequence. The 10-bit pattern decoded from the 20 following symbols indicates the bit index in the upstream pilot sequence associated with the detected upstream sync symbol. + +![Figure 10-6: Waveform diagram showing a downstream sync symbol followed by a modulated pilot sequence. The diagram shows levels for ONE and ZERO. The downstream sync symbol is at time position 256 and 0 to 6. The pilot sequence starts at time position 7 and continues through 255. The 10-bit pattern [0011011010] corresponds to bit index 364 in the upstream pilot sequence. The bit index is indicated by a double-headed arrow spanning from the start of the pilot sequence to the start of the next downstream sync symbol.](e91d950121dbb814d5c91603c7cd146e_img.jpg) + +Downstream Sync symbol Time position + +ONE + +ZERO + +Downstream Symbol count + +256 and 0 to 6 + +7 8 + +9 10 + +11 12 + +13 14 + +15 16 + +17 18 + +19 20 + +21 22 + +23 24 + +25 26 + +27 to 255 + +Bit index in upstream pilot sequence +10 bits [0011011010] = bit index 364 + +G.993.5(15)\_F10-6 + +Figure 10-6: Waveform diagram showing a downstream sync symbol followed by a modulated pilot sequence. The diagram shows levels for ONE and ZERO. The downstream sync symbol is at time position 256 and 0 to 6. The pilot sequence starts at time position 7 and continues through 255. The 10-bit pattern [0011011010] corresponds to bit index 364 in the upstream pilot sequence. The bit index is indicated by a double-headed arrow spanning from the start of the pilot sequence to the start of the next downstream sync symbol. + +**Figure 10-6 – Pattern modulated on subcarriers $10n+9$ following the sync symbol position of the vectored lines** + +#### 10.3.3.6 Initialization of multiple initializing lines + +When the VCE initializes multiple lines: + +- The downstream crosstalk channels from the initializing lines into the active lines of the vector group should be estimated simultaneously by insuring that O-P-VECTOR 1 signals are sent on all initialization lines during the estimation. This can be done by controlling the end and the start of O-P-VECTOR 1 in each line. +- The upstream crosstalk channels between the initializing lines and the active lines of the vector group should be estimated simultaneously by insuring that R-P-VECTOR 1 signals are sent on all initialization lines during the estimation. This can be done by controlling the end of R-P-VECTOR 1 with the O-P-SYNCHRO V1 signal in each line. + +### 10.3.4 Vectoring specific VTU-R signals transmitted during Channel Discovery phase + +#### 10.3.4.1 R-P-VECTOR 1 + +The VTU-R shall transmit R-P-QUIET signal until it correctly receives the O-SIGNATURE message. + +Upon receiving the O-SIGNATURE message, the VTU-R shall transmit R-P-VECTOR 1. + +The VTU-R shall identify the downstream Sync symbols positions and derive the upstream sync symbol positions, by detecting the sync symbol markers on the O-P-CHANNEL DISCOVERY V1 signal. + +The R-P-VECTOR 1 shall consist of sync symbols and quiet symbols only. Sync symbols shall be transmitted at each upstream sync symbol position (as defined in clause 7.3.2). Upstream sync symbol positions shall be the downstream sync symbol positions (as indicated by the markers on the O-P-CHANNEL DISCOVERY V1 signal), advanced or delayed by the upstream sync symbol offset (contained in the O-SIGNATURE message). Quiet symbols shall be transmitted at all other time positions (see Figure 10-2). + +The R-P-VECTOR 1 sync symbols shall be generated as described in clause 10.4.4 of [ITU-T G.993.2]. These sync symbols shall modulate a pilot sequence. The transmission of sync symbols shall start from the sync symbol that carries the first identified reference point of the + +upstream pilot sequence. The timing of reference points of the pilot sequence is indicated by the markers in the O-P-CHANNEL DISCOVERY V1 signal, as described in clause 10.3.3.5. + +The pilot sequence is a repetitive sequence, as defined in clause 6.2.3, assigned to the initializing line by the VCE and communicated to the VTU-R in the O-SIGNATURE message. Each probe tone of a sync symbol from the SUPPORTEDCARRIERs set with a pilot sequence bit equal to ZERO shall modulate a 00 constellation point, and with a pilot sequence bit equal to ONE shall modulate a 11 constellation point (the SUPPORTEDCARRIERs set is also indicated in the O-SIGNATURE message). The 00 and 11 constellation points shall be per the 4-QAM constellation defined in clause 10.3.3.2.1 of [ITU-T G.993.2]. The constellation points on subcarriers shall then be rotated by the quadrant scrambler defined in clause 12.3.6.2 of [ITU-T G.993.2]. + +The transmit PSD of all subcarriers shall be equal to CDPSDus and shall follow the upstream PSD limit imposed by the VTU-O as indicated in the O-SIGNATURE message. + +During transmission of R-P-VECTOR 1, the SOC is in its inactive state. + +During R-P-VECTOR 1, the VCE estimates the upstream FEXT channels from the initializing lines into the vectored lines. From this point on, FEXT cancellation matrices are established in the VTU-Os for all vectored lines in the upstream direction and FEXT from the initializing lines into vectored lines is cancelled. + +The duration of R-P-VECTOR 1 is determined by the VTU-O. The VTU-R shall end the transmission of the R-P-VECTOR 1 signal within 64 symbols after the last symbol of the O-P-SYNCHRO V1 signal. The duration of the R-P-VECTOR 1 shall not exceed $1024 \times 257$ symbols. + +The R-P-VECTOR 1 signal shall be followed by the R-P-CHANNEL DISCOVERY 1 signal. + +## 10.4 Training phase + +### 10.4.1 Overview + +The Channel Discovery phase is followed by the Training phase. If both downstream and upstream vectoring are disabled after the ITU-T G.994.1 Phase, then all vectoring-related parts shall be skipped and the Training phase shall be as defined in [ITU-T G.993.2]. + +If downstream vectoring or upstream vectoring is enabled, then the Training phase shall be modified relative to the ITU-T G.993.2 Training phase as defined in this clause. + +Figure 10-7 and Figure 10-8 highlight the signals added and the signals/messages modified in the ITU-T G.993.2 Training phase for ITU-T G.993.5 transceivers. Non-highlighted signals and messages shall be as defined in [ITU-T G.993.2]. + +![Sequence diagram showing early stages of the Training phase between Downstream and Upstream entities. The diagram includes columns for SOC messages and Signals for both entities. The training phase (VTU-O) is indicated by a vertical arrow on the left, and the training phase (VTU-R) by one on the right. Yellow boxes highlight specific messages: O-P-VECTOR 1-1, O-P-TRAINING V1, O-P-SYNCHRO V2, O-P-TRAINING 1, O-TA-UPDATE, R-P-QUIET V1, and R-P-VECTOR 1-1.](352d21d1e740e4a58cb17ab8656cfad8_img.jpg) + +The diagram illustrates the message exchange during the early stages of the Training phase. The vertical axis represents time, with the 'TRAINING phase (VTU-O)' indicated by an upward arrow on the left and the 'TRAINING phase (VTU-R)' indicated by an upward arrow on the right. + +**Downstream Messages:** + +- SOC messages:** O-IDLE, O-TA-UPDATE (highlighted in yellow), O-IDLE. +- Signals:** O-P-SYNCHRO 3, O-P-VECTOR 1-1 (highlighted in yellow), O-P-TRAINING V1 (highlighted in yellow), O-P-SYNCHRO V2 (highlighted in yellow), O-P-TRAINING 1 (highlighted in yellow), O-P-SYNCHRO 4, O-P-PILOT 2, O-P-ECT, O-P-TEQ, O-P-PILOT 3, O-P-PERIODIC 2, O-P-TRAINING 2, O-P-SYNCHRO 5. + +**Upstream Messages:** + +- Signals:** R-P-SYNCHRO 3, R-P-QUIET V1 (highlighted in yellow), R-P-VECTOR 1-1 (highlighted in yellow), R-P-TRAINING 1, R-P-SYNCHRO 4, R-P-TEQ, R-P-QUIET 3, R-P-ECT, R-P-PERIODIC 2, R-P-TRAINING 2, R-P-SYNCHRO 5. +- SOC messages:** R-IDLE, R-TA\_UPDATE, R-IDLE, R-ACK, R-IDLE. + +Horizontal dashed lines indicate the sequence of message exchanges between the Downstream and Upstream entities. + +Sequence diagram showing early stages of the Training phase between Downstream and Upstream entities. The diagram includes columns for SOC messages and Signals for both entities. The training phase (VTU-O) is indicated by a vertical arrow on the left, and the training phase (VTU-R) by one on the right. Yellow boxes highlight specific messages: O-P-VECTOR 1-1, O-P-TRAINING V1, O-P-SYNCHRO V2, O-P-TRAINING 1, O-TA-UPDATE, R-P-QUIET V1, and R-P-VECTOR 1-1. + +Figure 10-7 – Early stages of the Training phase + +![Sequence diagram showing the last stages of the Training phase between Downstream and Upstream entities. The Downstream side includes SOC messages (O-IDLE) and Signals (O-P-SYNCHRO 5, O-P-VECTOR 2, O-P-SYNCHRO V3, O-P-VECTOR 2-1, O-P-SYNCHRO V4). The Upstream side includes Signals (R-P-SYNCHRO 5, R-P-VECTOR 1-2, R-P-SYNCHRO V1, R-P-VECTOR 2, R-P-SYNCHRO V2) and SOC messages (R-IDLE/R-ERROR-FEEDBACK). Both sides have a 'Channel analysis and exchange phase'. Vertical arrows on the sides indicate the 'TRAINING phase (VTU-O)' and 'TRAINING phase (VTU-R)'.](fd8f5da2b60cdca94896f3cde8ee81f0_img.jpg) + +Sequence diagram showing the last stages of the Training phase between Downstream and Upstream entities. The Downstream side includes SOC messages (O-IDLE) and Signals (O-P-SYNCHRO 5, O-P-VECTOR 2, O-P-SYNCHRO V3, O-P-VECTOR 2-1, O-P-SYNCHRO V4). The Upstream side includes Signals (R-P-SYNCHRO 5, R-P-VECTOR 1-2, R-P-SYNCHRO V1, R-P-VECTOR 2, R-P-SYNCHRO V2) and SOC messages (R-IDLE/R-ERROR-FEEDBACK). Both sides have a 'Channel analysis and exchange phase'. Vertical arrows on the sides indicate the 'TRAINING phase (VTU-O)' and 'TRAINING phase (VTU-R)'. + +G.993.5(15)\_F10-8 + +Figure 10-8 – Last stages of the Training phase + +### 10.4.2 Modified SOC messages sent during the Training phase + +#### 10.4.2.1 O-TA\_UPDATE + +The O-TA\_UPDATE message (defined in Table 12-32 of [ITU-T G.993.2]) which is transmitted during O-P-TRAINING 2 contains an ITU-T G.993.5 parameter field. The ITU-T G.993.5 parameter field contains several parameters needed for FEXT cancellation operation, as shown in Table 10-13. + +Table 10-13 – Parameter field in message O-TA\_UPDATE + +| Field | Field name | Format | +|-------|----------------------------------------|---------------------------------------| +| 1 | ITU-T G.993.5 parameter field length | 1 byte | +| 2 | Error report control parameters | Error report configuration descriptor | +| 3 | SOC repetition factor (1/R) | 1 byte | +| 4 | FEXT estimation symbols per superframe | 1 byte | + +Field #1, "ITU-T G.993.5 parameter field length", indicates the length of the ITU-T G.993.5 parameter field in bytes, excluding the ITU-T G.993.5 parameter field length field. All fields shown in Table 10-13 shall be included in the O-TA\_UPDATE message. The field shall be represented as an unsigned integer. + +Field #2, "error report control parameters", defines the control parameters for each of the vectored bands indicated in O-SIGNATURE. The control parameters are defined in Table 7-1 and valid values are defined in Table 7-2. The values defined in this field may include optional values indicated by the VTU-R in R-MSG1. Table 8-4 defines the mapping of the control parameters into the Error Report configuration descriptor. The VTU-O shall select control parameters so that in conjunction with the selected SOC repetition rate, the expected duration of the ERROR\_FEEDBACK message will not exceed the limits defined in clause 10.4.2.2. + +Field #3, "SOC Repetition Factor", defines the SOC repetition factor, $1/R$ , as set by the VCE. The valid $1/R$ values are all multiples of 10 in the [10, 120] range. This corresponds to the number of bits per symbol ( $N\_bits\_per\_symbol$ ) of the SOC being a multiple of 16 in the [16, 192] range. The field shall be represented as an unsigned integer. + +Field #4, "FEXT estimation symbols per superframe", defines the number of symbols ( $K$ ) in the superframe for which a clipped error sample shall be reported. The clipped error samples shall be reported in a format defined by Field #2. The field shall be formatted as an unsigned integer with valid values $K=1, 2, 4, 6, \text{ and } 8$ . The value of $K$ shall not exceed the VTU-R capability ( $K_{max}$ ) indicated in the R-MSG1 message. Clause 10.4.2.2 defines the symbol positions for which clipped error samples shall be reported for different values of $K$ . + +The O-TA\_UPDATE message may indicate a correction to the timing advance (TA) value. If the TA value contained in the O-TA\_UPDATE message is different from the TA value previously used by the VTU-R, then the TA value shall be updated starting with the first symbol following R-P-SYNCHRO 5. + +NOTE – This requirement is different from the way the TA value is updated in [ITU-T G.993.2]. + +#### 10.4.2.2 R-ERROR-FEEDBACK + +During transmission of R-P-VECTOR 2, the VTU-R shall report back to the VTU-O the clipped error samples through the SOC using R-ERROR-FEEDBACK messages (see Figure 10-8). The SOC message code for this message shall be 8B16. The VTU-O shall not acknowledge any of R-ERROR-FEEDBACK messages and the VTU-R shall not re-transmit any of them. + +The R-ERROR-FEEDBACK messages shall be alternated with R-IDLE. Figure 10-9 shows the timeline of R-IDLE and the R-ERROR-FEEDBACK message for subsequent symbols on which the clipped error samples are reported. The sequence shall start from R-IDLE. Both R-IDLE and the R-ERROR-FEEDBACK message shall use the extended SOC channel with settings as described in clause 10.4.4.4. The rest of R-IDLE parameters shall be the same as for R-IDLE defined in clause 12.2.4 of [ITU-T G.993.2]: it shall consist of HDLC flag 7E16 sent repeatedly. + +The first R-IDLE transmission (after completion of R-P-VECTOR 1-2) allows the receiver in the VTU-O to adjust to the extended SOC channel and shall be at least 16 symbols long. The duration of the other R-IDLE transmissions (denoted as $t_{IDLE}$ in Figure 10-9) shall be set by the VTU-R so that the VTU-R can complete the R-ERROR-FEEDBACK message during the time which is less than the time period between two adjacent symbols on which the clipped error samples have to be reported. Each time period $t_{IDLE}$ shall be at least two symbols long. Transmission of R-ERROR-FEEDBACK message shall start at the time $t_{START}$ that shall be inside the transmission window (see Figure 10-9). The transmission window starts three symbol periods (i.e., $3 / f_{DMT}$ ) after the start of the symbol on which the clipped error samples are reported. The transmission window ends $W_{max}$ symbol periods (i.e., $W_{max} / f_{DMT}$ ) after the start of the symbol on which the clipped error samples are reported. The maximum value of $t_{IDLE}$ depends on the length of the R-ERROR-FEEDBACK message. The total of the value of $t_{IDLE}$ and the duration of the transmission of the R-ERROR-FEEDBACK message shall not exceed the time-limit that will prevent the VTU-R to start transmission of the next R-ERROR-FEEDBACK message inside the next transmission window. + +![Figure 10-9 – Timeline of R-ERROR-FEEDBACK messages. The diagram shows a sequence of R-IDLE and R-ERROR-FEEDBACK messages over time. Below the messages, a timeline shows O-P-VECTOR 2-1 symbol reporting intervals. Each interval starts at t_START and has a duration of W_max / f_DMT. The first interval is labeled 'O-P-VECTOR 2-1 symbol reporting #i-1', the second '#i', and the third '#i+1'. The time between the start of one interval and the next is t_IDLE. The diagram also shows the relationship between the R-ERROR-FEEDBACK messages and the symbol reporting intervals, with the first R-ERROR-FEEDBACK message occurring during the first symbol reporting interval.](15de63f0b5df62e6ab9164f2a72e2e33_img.jpg) + +Figure 10-9 – Timeline of R-ERROR-FEEDBACK messages. The diagram shows a sequence of R-IDLE and R-ERROR-FEEDBACK messages over time. Below the messages, a timeline shows O-P-VECTOR 2-1 symbol reporting intervals. Each interval starts at t\_START and has a duration of W\_max / f\_DMT. The first interval is labeled 'O-P-VECTOR 2-1 symbol reporting #i-1', the second '#i', and the third '#i+1'. The time between the start of one interval and the next is t\_IDLE. The diagram also shows the relationship between the R-ERROR-FEEDBACK messages and the symbol reporting intervals, with the first R-ERROR-FEEDBACK message occurring during the first symbol reporting interval. + +G.993.5(15)\_F10-9 + +**Figure 10-9 – Timeline of R-ERROR-FEEDBACK messages** + +Through the O-TA\_UPDATE message, the VCE indicates how many FEXT estimation symbols per superframe (i.e., the value of $K$ determined by the O-TA\_UPDATE message) the clipped error samples shall be reported. For the given value of $K$ (assigned by O-TA\_UPDATE), the VTU-R shall report clipped error samples for all the O-P-VECTOR 2-1 symbols of each downstream superframe with symbol count $i(k) = (k+1) \times \lfloor 256/K \rfloor$ , where $k = 0, 1, 2, \dots, K-1$ . The value of $W\_max$ for the given value of $K$ shall be computed as $W\_max = \lfloor 257/K \rfloor - 2$ . + +NOTE 1 – If $K=1$ , the VTU-R reports clipped error samples on the O-P-VECTOR 2-1 downstream sync symbols only. + +The number of bytes used to report the clipped error samples in a single R-ERROR-FEEDBACK message depends on the backchannel control parameters indicated in the O-TA\_UPDATE message. The total number of bytes to be transmitted is equal to the number of bytes in the ERB, $N\_ERB$ , plus 3 (see Table 10-14). + +If the size of the R-ERROR\_FEEDBACK message is larger than the maximum allowed segment size, the message shall be segmented as defined in clause 12.2.6 of [ITU-T G.993.2] for AR mode, with the number of segments not to exceed 15. All segments except the last one shall be set to be of the maximum allowed segment size. + +NOTE 2 – Minimum gaps between segments reduce the overhead of error feedback transmission and thus save bandwidth of the backchannel. + +The number of symbols required to communicate this number of bytes can be calculated as: + +$$N\_symbol = \left\lceil \frac{8 \times (N\_ERB + 3 + N\_OH)}{N\_bits\_per\_symbol} \right\rceil = \left\lceil 5 \times \frac{N\_ERB + 3 + N\_OH}{1/R} \right\rceil$$ + +where $N\_OH$ is the SOC encapsulation overhead, equal to 6 octets plus the statistical overhead due to byte stuffing, as specified in [ITU-T G.997.1]. If the R-ERROR-FEEDBACK message is segmented, the $N\_OH$ (per segment) shall be multiplied by the number of segments. + +NOTE 3 – The 0.1% worst case statistical overhead due to byte stuffing for a message with randomized content that is longer than 512 bytes is not expected to be more than 3% and goes down for longer messages. + +NOTE 4 – When padding is not used, $N\_ERB$ will depend on the actual values of the error samples. In that case, the number of bytes per symbol should be calculated based on the worst-case assumption of the resolution needed for the error samples. + +The VCE shall configure the SOC bit rate, such that the value of $N\_symbol$ (including the statistical overhead due to byte stuffing) does not exceed $(\lfloor 257/K \rfloor - 2)$ symbols (with $K$ the number of symbols per superframe on which clipped error samples are reported, as indicated in the O-TA\_UPDATE message). The VTU-R shall terminate transmission of the R-ERROR- + +FEEDBACK message if its duration (due to unexpectedly high SOC overhead) will prevent the VTU-R to start transmission of the next R-ERROR-FEEDBACK message inside the next transmission window. + +The message R-ERROR\_FEEDBACK shall have the structure shown in Table 10-14. + +**Table 10-14 – Description of message R-ERROR\_FEEDBACK** + +| | Field name | Format | +|---|--------------------|------------------------| +| 1 | Message descriptor | Message code | +| 2 | Sync symbol count | 2 bytes | +| 3 | Error report block | N ERB bytes | + +Field #1, "Message descriptor", is a unique one-byte code that identifies the message. It shall be coded 8B16. + +Field #2, "Sync symbol count", contains the sync symbol count modulo 1024 of the last received downstream sync symbol and the sequence number $k = 0, \dots, K - 1$ of the report in the superframe. The VTU-R shall count sync symbols starting from the first downstream sync symbol after it receives O-P-SYNCHRO V3 (this sync symbol shall have count 0) through transmission of O-P-VECTOR 2-1. + +The four MSBs of the 2-byte field shall represent the sequence number $k$ of the report as an unsigned integer in the range from 0 to $K - 1$ . The ten LSBs shall represent the sync symbol count as an unsigned integer in the range from 0 to 1023. The bits 10 and 11 are reserved by ITU-T and shall be set to 0. + +NOTE 5 – If the ERB is reported for a sync symbol, the "sync symbol count" field has the four MSBs set to $K - 1$ and the ten LSBs set to the count of the sync symbol for which the ERB is reported. + +Field #3, "Error report block", contains the real and imaginary parts of the clipped error samples associated with the subcarriers of the indicated vectored band(s). If only a single band is reported in the R-ERROR-FEEDBACK message, then the NERB shall be calculated (see clause 7.2.3.3) as if $L_w=0$ for the other bands. The format is defined in clause 7.2.3. + +### 10.4.3 Vectoring specific VTU-O signals transmitted during the Training phase + +#### 10.4.3.1 O-P-VECTOR 1-1 + +The O-P-SYNCHRO 3 signal shall be followed by the O-P-VECTOR 1-1 signal. + +The O-P-VECTOR 1-1 signal shall be identical to the O-P-VECTOR 1 signal, except that the PSD shall be equal to MREFPSDds. + +The duration of O-P-VECTOR 1-1 is vendor discretionary, but shall be minimum $4 \times 257$ symbols and maximum $1024 \times 257$ symbols. + +During transmission of O-P-VECTOR 1-1, the SOC is in its inactive state. + +The O-P-VECTOR 1-1 signal allows the downstream FEXT channel re-estimation from the initializing line into the vectored lines. This re-estimation is to capture changes in the FEXT channels caused by possible modifications of the VTU-O AFE configurations during the Channel Discovery phase. + +The O-P-VECTOR 1-1 signal shall be followed by the O-P-TRAINING V1 signal, which determines the actual duration of O-P-VECTOR 1-1. + +#### **10.4.3.2 O-P-TRAINING V1** + +The O-P-TRAINING V1 signal shall be identical to the O-P-TRAINING 1 signal defined in clause 12.3.4.3.1.1 of [ITU-T G.993.2], with the addition of markers to indicate the downstream sync symbol positions and upstream pilot sequence position. Markers shall be added as defined in clause 10.3.3.5. The pattern of markers shall be continued taking into account all downstream sync symbol positions from the beginning of the O-P-CHANNEL DISCOVERY V1 signal. + +During the transmission of O-P-TRAINING V1, the SOC is in its inactive state. + +The O-P-TRAINING V1 signal shall be followed by the O-P-SYNCHRO-V2 signal, which determines the actual duration of the O-P-TRAINING V1. + +#### **10.4.3.3 O-P-SYNCHRO V2** + +The O-P-SYNCHRO V2 signal shall be identical to the O-P-SYNCHRO 4 signal described in clause 12.3.4.3.1 of [ITU-T G.993.2]. + +During transmission of O-P-SYNCHRO V2, the SOC is in its inactive state. + +With the VTU-O transmitting the O-P-SYNCHRO V2 signal, the VCE notifies the VTU-R that the upstream FEXT channel re-estimation from the initializing lines into other vectored lines is completed, and that the VTU-R shall stop transmission of the R-P-VECTOR 1-1 signal. + +The VTU-O shall transmit O-P-SYNCHRO V2 only after the VCE detects the R-P-VECTOR 1-1 signal transmitted during at least $4 \times 257$ symbols. + +The O-P-SYNCHRO V2 signal shall be followed by the O-P-TRAINING 1 signal. + +#### **10.4.3.4 O-P-TRAINING 1 and O-P-TRAINING 2** + +These signals shall be identical to the O-P-TRAINING 1 and O-P-TRAINING 2 signals defined in clause 12.3.4.3.1 of [ITU-T G.993.2], respectively, with the addition of markers to indicate the downstream sync symbol positions and upstream pilot sequence positions (as defined in clause 10.3.3.5). The pattern of markers shall be continued taking into account all downstream sync symbol positions from the beginning of O-P-CHANNEL DISCOVERY V1. + +NOTE – It is beneficial if O-P-SYNCHRO 4 and O-P-SYNCHRO 5 signals are not transmitted at downstream sync symbol positions. + +#### **10.4.3.5 O-P-VECTOR 2** + +The O-P-VECTOR 2 signal shall follow the O-P-SYNCHRO 5 signal. + +At sync symbol positions, the O-P-VECTOR 2 signal shall contain sync symbols, modulated as defined for the O-P-VECTOR 1 signal. At other symbol positions, the SOC channel shall be modulated using one byte per symbol mapping, as defined for the O-P-TRAINING 2 signal in [ITU-T G.993.2]. + +During the sync symbols, the SOC is in the inactive state. During the other symbols, the SOC is in the active state, and the VTU-O shall transmit O-IDLE. + +The minimum duration of O-P-VECTOR 2 is 128 symbols. + +The O-P-VECTOR 2 signal shall be followed by the O-P-SYNCHRO V3 signal, which determines the actual duration of O-P-VECTOR 2. + +The VTU-O shall transmit O-P-SYNCHRO V3 at least 70 symbols prior to transmission of the sync symbol (to avoid ambiguity in sync symbol count at the VTU-R). + +#### **10.4.3.6 O-P-SYNCHRO V3** + +The O-P-SYNCHRO V3 signal shall be identical to the O-P-SYNCHRO 5 signal, as defined in clause 12.3.4.3.1.9 of [ITU-T G.993.2]. + +During transmission of O-P-SYNCHRO V3, the SOC is in its inactive state. + +With the VTU-O transmitting the O-P-SYNCHRO-V3 signal, the VCE notifies the VTU-R that the upstream FEXT channel re-estimation from the initializing line into other vectored lines is completed, and that the VTU-R shall stop transmission of the R-P-VECTOR 1-2 signal. The VTU-O shall transmit O-P-SYNCHRO V3 only after the VCE detects the R-P-VECTOR 1-2 signal transmitted during at least $4 \times 257$ symbols. + +The O-P-SYNCHRO V3 signal shall be followed by the O-P-VECTOR 2-1 signal. + +#### **10.4.3.7 O-P-VECTOR 2-1** + +The O-P-VECTOR 2-1 signal shall be identical to the O-P-VECTOR 2 signal. + +During the sync symbols, the SOC is in the inactive state. During the other symbols, the SOC is in the active state, and the VTU-O shall transmit O-IDLE. + +Transmission of O-P-VECTOR 2-1 enables the VCE to estimate the downstream FEXT channels from the vectored lines into the initializing line, and to update the estimates of the downstream FEXT channels from the initializing lines into the vectored lines. + +The duration of O-P-VECTOR 2-1 is vendor discretionary, but shall be minimum 257 symbols and maximum $1024 \times 257$ symbols. + +The O-P-VECTOR 2-1 signal shall be followed by the O-P-SYNCHRO V4 signal, which determines the actual duration of the O-P-VECTOR 2-1. + +#### **10.4.3.8 O-P-SYNCHRO V4** + +The O-P-SYNCHRO V4 signal shall be identical to the O-P-SYNCHRO V3 signal, as defined in clause 10.4.3.6. + +During transmission of the O-P-SYNCHRO V4 signal, the SOC is in its inactive state. + +With the VTU-O transmitting the O-P-SYNCHRO-V4 signal, the VCE notifies the VTU-R that the downstream FEXT channel estimation from the other vectored lines into the initializing lines is completed, and that the VTU-R shall stop transmission of the R-P-VECTOR 2 signal. + +The Training phase is completed at this point, and the VTU-O shall transition into the Channel Analysis and Exchange phase, see Figure 10-8. + +#### **10.4.3.9 Initialization of multiple initializing lines** + +When the VCE initializes multiple lines: + +- The downstream crosstalk channel from the initializing lines into the active lines of the vector group should be estimated simultaneously by insuring that O-P-VECTOR 1-1 signals are sent on all initialization lines during the estimation. This can be done by controlling the start and the end of O-P-VECTOR 1-1 in each line. +- The upstream crosstalk channel between the initializing lines and the active lines of the vector group should be estimated simultaneously by insuring that R-P-VECTOR 1-1 signals are sent on all initialization lines during the estimation. This can be done by controlling the end of R-P-VECTOR 1-1 with the O-P-SYNCHRO V2 signal in each line. +- The upstream crosstalk channels between the initializing lines and the active lines of the vector group should be estimated simultaneously by insuring that R-P-VECTOR 1-2 signals are sent on all initialization lines during the estimation. This can be done by controlling the end of R-P-VECTOR 1-2 with the O-P-SYNCHRO V3 signal in each line. +- The downstream crosstalk channel from the active lines into the initializing lines of the vector group should be estimated simultaneously by insuring that O-P-VECTOR 2-1 + +signals are sent on all initialization lines during the estimation. This can be done by controlling the end of O-P-VECTOR 2-1 with the O-P-SYNCHRO V4 signal in each line. + +### **10.4.4 Vectoring specific VTU-R signals transmitted during the Training phase** + +#### **10.4.4.1 R-P-QUIET V1** + +The R-P-SYNCHRO 3 signal shall be followed by the R-P-QUIET V1 signal. + +The R-P-QUIET V1 signal shall be identical to the R-P-QUIET 2 signal. + +During the R-P-QUIET V1 signal, the SOC is in its inactive state. + +The duration of R-P-QUIET V1 signal is controlled by the VTU-O. The VTU-R shall end the transmission of R-P-QUIET V1 upon detection of the O-P-TRAINING V1 signal, and start transmission of R-P-VECTOR 1-1 signal. + +#### **10.4.4.2 R-P-VECTOR 1-1** + +The R-P-VECTOR 1-1 signal shall be identical to the R-P-VECTOR 1 signal, except its PSD shall be equal to MREFPSDus. + +During transmission of R-P-VECTOR 1-1, the SOC is in its inactive state. + +The VTU-R should use the timing advance value calculated in the Channel Discovery phase to ensure that the sync symbols of the initializing line are aligned at the VTU-O with the sync symbols of vectored lines. + +The R-P-VECTOR 1-1 signal allows the upstream FEXT channel re-estimation between the initializing line and the vectored lines. This re-estimation is to capture changes in the FEXT channels caused by possible modifications of the VTU-O AFE configurations during the Channel Discovery phase. + +The duration of R-P-VECTOR 1-1 signal is controlled by the VTU-O. Within 64 symbols after the last symbol of the O-P-SYNCHRO V2 signal, the VTU-R shall end the transmission of the R-P-VECTOR 1-1. The duration of R-P-VECTOR 1-1 shall not exceed $1024 \times 257$ symbols. + +The R-P-VECTOR 1-1 signal shall be followed by the R-P-TRAINING 1 signal. + +#### **10.4.4.3 R-P-VECTOR 1-2** + +The R-P-VECTOR 1-2 signal shall follow the R-P-SYNCHRO 5 signal. The R-P-VECTOR 1-2 signal shall be identical to the R-P-VECTOR 1-1 signal. + +During transmission of R-P-VECTOR 1-2, the SOC is in its inactive state. + +The R-P-VECTOR 1-2 signal allows the upstream FEXT channel re-estimation between the initializing line and the vectored lines. This re-estimation is to capture changes in the FEXT channels caused by possible modifications of the timing advance during the Training phase. + +The duration of R-P-VECTOR 1-2 signal is controlled by the VTU-O. Within 64 symbols after the last symbol of the O-P-SYNCHRO V3 signal, the VTU-R shall end the transmission of the R-P-VECTOR 1-2 signal. The duration of R-P-VECTOR 1-2 shall not exceed $1024 \times 257$ symbols. + +The R-P-VECTOR 1-2 signal shall be followed by the R-P-SYNCHRO V1 signal. + +#### **10.4.4.4 R-P-SYNCHRO V1** + +The R-P-SYNCHRO V1 signal shall be identical to the R-P-SYNCHRO 5 signal, as defined in clause 12.3.4.3.2.9 of [ITU-T G.993.2]. + +During transmission of the R-P-SYNCHRO V1 signal, the SOC is in its inactive state. + +The R-P-SYNCHRO V1 signal shall be followed by R-P-VECTOR 2 signal. + +#### 10.4.4.5 R-P-VECTOR 2 + +At sync symbol positions, the R-P-VECTOR 2 signal shall contain sync symbols, modulated as defined for the R-P-VECTOR 1 signal. At other symbol positions, the symbols shall be modulated as for the R-P-TRAINING 2 signal, with the extended SOC channel being established. + +Transmission of R-P-VECTOR 2 enables the VCE to estimate upstream FEXT channels from the vectored lines into the initializing line, and update the estimates of the upstream FEXT from the initializing lines into the vectored lines. + +During the sync symbols, the SOC is in the inactive state. During the other symbols, the SOC is in the active state, and the VTU-R shall transmit R-IDLE or the R-ERROR-FEEDBACK message. + +The duration of R-P-VECTOR 2 signal is controlled by the VTU-O. Within 64 symbols after the last symbol of the O-P-SYNCHRO V4 signal, the VTU-R shall end the transmission of the R-P-VECTOR 2 signal. + +The R-P-VECTOR 2 signal shall be followed by the R-P-SYNCHRO V2 signal. + +To establish the extended SOC, the R-P-VECTOR 2 symbols with active SOC shall be modulated with bit mapping as defined in Table 10-15, with the number of bits per symbol calculated as: + +$$N_{\text{bitspersymbol}} = \frac{16}{10 \cdot R}$$ + +with $1/R$ an integer multiple of 10 in the [10, 120] range, as indicated in the O-TA\_UPDATE message. + +**Table 10-15 – Bit mapping for R-P-VECTOR 2** + +| Subcarrier index | Constellation point | +|---------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $5, 10, 15, \dots, 5n, \dots$ | 00 | +| $1, 1/R+1, 2/R+1, \dots, n/R + 1, \dots$ | SOC message bits 0 and 1 | +| $2, 1/R+2, 2/R+2, \dots, n/R + 2, \dots$ | SOC message bits 2 and 3 | +| ... | ... | +| $10k+m, 1/R+10k+m, 2/R+10k+m, \dots, n/R+10k+m, \dots$
with $k = 0, 1, 2, \dots, \frac{1}{10 \cdot R} - 1$
and $m = 1, 2, 3, 4, 6, 7, 8, 9$ | SOC message bits $16k+f(m)$ and $16k+f(m)+1$ with
$f(m) = \begin{cases} 2m - 2 & \text{if } m = 1, 2, 3, 4 \\ 2m - 4 & \text{if } m = 6, 7, 8, 9 \end{cases}$ | +| ... | ... | +| $1/R-1, 2/R-1, 3/R-1, \dots, n + 1/R-1, \dots$ | SOC message bits $\frac{16}{10 \cdot R} - 2$ and $\frac{16}{10 \cdot R} - 1$ | + +NOTE – In [ITU-T G.993.2], the SOC bit mapping allows 16 bits per symbol. For faster reporting of clipped error samples, the VCE may increase the SOC bit mapping in steps of 16 bits per symbol, from 16 bits up to 192 bits per symbol, by reducing the number of repetitions of these bits within each symbol. For operation at 4000 symbols/s, this increases the SOC bit rate in steps of 64 kbit/s, from 64 kbit/s (as in [ITU-T G.993.2]) up to 768 kbit/s. For operation at 8000 symbols/s, this increases the SOC bit rate in steps of 128 kbit/s, from 128 kbit/s (as in [ITU-T G.993.2]) up to 1536 kbit/s. + +#### 10.4.4.6 R-P-SYNCHRO V2 + +The R-P-SYNCHRO V2 signal shall be identical to the R-P-SYNCHRO V1 signal. + +During transmission of the R-P-SYNCHRO V2 signal, the SOC is in its inactive state. + +The Training phase is completed at this point, and VTU-R shall transition into the Channel Analysis and Exchange phase, see Figure 10-8. + +## 10.5 Channel Analysis and Exchange phase + +### 10.5.1 Overview + +The Channel Analysis and Exchange phase does not require any changes with respect to [ITU-T G.993.2], other than the ITU-T G.993.5 parameter field defined for the O-PMS message. + +### 10.5.2 Modified SOC messages sent during Channel Analysis and Exchange phase + +#### 10.5.2.1 O-PMS + +The O-PMS message (defined in Table 12-46 of [ITU-T G.993.2]) which is transmitted during O-P-MEDLEY contains an ITU-T G.993.5 parameter field. The ITU-T G.993.5 parameter field contains several parameters needed for FEXT cancellation operation as shown in Table 10-16. + +**Table 10-16 – ITU-T G.993.5 parameter field in message O-PMS** + +| Field | Field name | Format | +|-------|--------------------------------------|---------| +| 1 | ITU-T G.993.5 parameter field length | 1 byte | +| 2 | Showtime backchannel encapsulation | 1 byte | +| 3 | Layer 2 VCE MAC address | 6 bytes | +| 4 | Layer 2 Line_ID | 2 bytes | + +Field #1, "ITU-T G.993.5 parameter field length", indicates the length of the ITU-T G.993.5 parameter field in bytes, excluding the ITU-T G.993.5 parameter field length field. All fields shown in Table 10-16 shall be included in the O-PMS message. The field shall be represented as an unsigned integer. + +Field #2, "Showtime backchannel encapsulation", defines whether the Showtime backchannel is encapsulated into eoc messages or into Layer 2 Ethernet packets. The field shall be set to 0016 for eoc encapsulation and shall be set to 0116 for Layer 2 Ethernet encapsulation. Other values are reserved for ITU-T. + +Field #3, "Layer 2 VCE MAC Address", defines the VCE MAC Address to be used by the NT as MAC destination address in case Layer 2 Ethernet encapsulation is used. The field shall be set to all 0016 bytes in case eoc encapsulation is used. + +Field #4, "Layer 2 Line\_ID", defines the Line\_ID to be used by the NT in case Layer 2 Ethernet encapsulation is used. The Line\_ID shall be inserted as the first two bytes of the Ethernet packet payload (see Figure 7-9). The field shall be set to 000016 in case eoc encapsulation is used. + +## 10.6 Transition from initialization to Showtime + +The last symbol of O-P-SYNCHRO 6 shall be transmitted at a downstream sync symbol position, such that the first symbol of Showtime is a data symbol transmitted at downstream symbol count 0. + +The first DMT symbol following O-P-SYNCHRO 6 of the Channel Analysis and Exchange phase shall be the first downstream symbol of Showtime. The PMD, PMS-TC and TPS-TC parameter settings negotiated during the Channel Analysis and Exchange phase shall be applied starting from the first symbol of Showtime. + +The last symbol of R-P-SYNCHRO 6 shall be transmitted at an upstream sync symbol position, such that the first symbol of Showtime is a data symbol transmitted at upstream symbol count 0. + +The first DMT symbol following R-P-SYNCHRO 6 shall be the first upstream symbol of Showtime. The PMD, PMS-TC and TPS-TC parameter settings negotiated during the Channel Analysis and Exchange phase shall be applied starting from the first symbol of Showtime. + +The last symbol of R-P-SYNCHRO 6 shall be transmitted at least 15 and no more than 15+64+257 symbols after transmission of the last symbol of O-P-SYNCHRO 6. + +The downstream sync symbol positions and the downstream pilot sequence shall be continued from initialization into Showtime. Each downstream sync symbol in Showtime shall be modulated by the downstream pilot sequence (see clause 6.2.3). + +The upstream sync symbol positions and the upstream pilot sequence shall be continued from initialization into Showtime. Each upstream sync symbol in Showtime shall be modulated by the upstream pilot sequence (see clause 7.3.3). + +## **10.7 Loop diagnostic mode procedures** + +### **10.7.1 Overview** + +The loop diagnostic mode procedure described in this clause is based on the initialization as described in clause 10.1 through 10.6, with addition of steps specific for loop diagnostic mode, and without sending R-ERROR-FEEDBACK messages. + +If the loop diagnostic mode codepoint in the MS message is set (see clauses 12.3.2.1.2 and 12.3.2.2.2 of [ITU-T G.993.2]), then the loop diagnostic mode shall be entered after completion of the ITU-T G.994.1 Handshake phase. Loop diagnostic mode shall be entered upon request by either VTU. Both VTUs shall support the loop diagnostic mode. + +The sequence of stages in the loop diagnostic mode shall be the same as for initialization (defined in clauses 10.1 through 10.6) up to the Channel Analysis and Exchange phase, where the test parameters listed in Table 12-64 of [ITU-T G.993.2] and defined in clause 11.4.1 of [ITU-T G.993.2] are exchanged. However, the test parameters for the quiet line noise (QLN) and the channel characteristics function (Hlog) shall be measured and exchanged during the Channel Discovery phase, as described in clause 12.4.3 of [ITU-T G.993.2]. + +The time-outs specified in clause 12.3.1 of [ITU-T G.993.2] do not apply to loop diagnostic mode. Time-out values are for further study. + +#### **10.7.1.1 SOC message mapping during loop diagnostic mode** + +See clause 12.4.1.1 of [ITU-T G.993.2]. + +### **10.7.2 Channel discovery and training phases of loop diagnostic mode** + +#### **10.7.2.1 SOC messages exchanged during the channel discovery and training phases of loop diagnostic mode** + +The SOC messages for the Channel Discovery phase and the Training phase of the loop diagnostic mode shall be the same as for the initialization procedure described in clauses 10.3 and 10.4, respectively, except for O-PRM, R-PRM, R-MSG1 and O-TA\_UPDATE. + +##### **10.7.2.1.1 O-PRM & R-PRM** + +The test parameters for the QLN and the channel characteristics function, Hlog, shall be measured and exchanged during the Channel Discovery phase in the O-PRM-LD and R-PRM-LD messages described in clause 12.4.2.1 of [ITU-T G.993.2], which replace O-PRM and R-PRM. + +NOTE – Field #13 and field #14 in O-PRM and R-PRM contain the ITU-T G.998.4 parameter field and the ITU-T G.993.5 parameter field. While field #13 and field #14 in O-PRM-LD and R-PRM-LD contain QLN and Hlog. + +##### **10.7.2.1.2 R-MSG1 (supplements clause 10.3.2.2)** + +Field #2, "maximum number of FEXT estimation symbols per superframe", defines the maximum number ( $K_{max}$ ) of symbols in the superframe for which the VTU-R supports error sample reporting. The field shall be formatted as an unsigned integer with value $K_{max} = 0$ . + +Field #3, "support of optional backchannel control parameters", indicate the optional values of control parameters supported by the VTU-R. The field shall be formatted as an unsigned integer with value $00_{16}$ . + +NOTE – This text is identical to Annex Y, clause Y.10.3.2.2 of [ITU-T G.993.2]. + +##### **10.7.2.1.3 O-TA\_UPDATE (supplements clause 10.4.2.1)** + +Field #2, "error report control parameters", defines the control parameters for each of the vectored bands indicated in O-SIGNATURE. The VTU-R shall ignore the error report control parameters. + +Field #3, "SOC Repetition Factor", defines the SOC repetition factor, $1/R$ , as set by the VCE. The VTU R shall ignore this field. + +Field #4, "FEXT estimation symbols per superframe", defines the number of symbols ( $K$ ) in the superframe for which a clipped error sample shall be reported. The field shall be formatted as an unsigned integer with value $K = 0$ . + +NOTE – This text is identical to clause Y.10.4.2.1, Annex Y of [ITU-T G.993.2], except for field #3. + +#### **10.7.2.2 Signals transmitted during the channel discovery and training phases** + +The signals transmitted during the channel discovery and training phases are the same as defined in clauses 10.3 and 10.4 for initialization, with the following exceptions: + +- the SOC message mapping shall be as defined in clause 12.4.1.1 of [ITU-T G.993.2]; +- the duration of O-P-QUIET 1 shall be at least 8192 symbols but not longer than 16384 symbols; +- R-P-VECTOR 2 definition. + +##### **10.7.2.2.1 R-P-VECTOR 2 (replaces clause 10.4.4.5)** + +At sync symbol positions, the R-P-VECTOR 2 signal shall contain sync symbols, modulated as defined for the R-P-VECTOR 1 signal. At other symbol positions, the symbols shall be modulated as for the R-P-TRAINING 2 signal, with the SOC message mapping as defined in clause 12.4.1.1 of [ITU-T G.993.2]. + +Transmission of R-P-VECTOR 2 enables the VCE to estimate upstream FEXT channels from the vectored lines into the initializing line, and update the estimates of the upstream FEXT from the initializing lines into the vectored lines. + +During the sync symbols, the SOC is in the inactive state. During the other symbols, the SOC is in the active state, and the VTU-R shall transmit the R-IDLE message. + +The duration of R-P-VECTOR 2 signal is controlled by the VTU-O. Within 64 symbols after the last symbol of the O-P-SYNCHRO V4 signal, the VTU-R shall end the transmission of the R-P-VECTOR 2 signal. + +The R-P-VECTOR 2 signal shall be followed by the R-P-SYNCHRO V2 signal. + +NOTE 1 – The R-P-VECTOR 2 signal in loop diagnostic mode is identical to the R-P-VECTOR 2 signal defined in clause 10.4.4.5 for initialization, without extended SOC and with the VTU-R transmitting R-IDLE messages instead of R-ERROR-FEEDBACK messages. + +NOTE 2 – This text is identical to clause Y.10.4.4.5, Annex Y of [ITU-T G.993.2], except for the SOC message mapping. + +### **10.7.3 Channel Analysis and Exchange phase of loop diagnostic mode** + +The Channel Analysis and Exchange phase of loop diagnostic mode in ITU-T G.993.5 does not require any changes in comparison to loop diagnostic mode in [ITU-T G.993.2]. + +# **11 Configuration and test parameters** + +This Recommendation defines configuration parameters and test parameters that shall be accessible through the central office-management information base (CO-MIB). The configuration parameters are defined in clause 11.1. The test parameters are defined in clause 11.2. Configuration parameters and test parameters are defined in [ITU-T G.997.1] as management objects accessible over the Q-interface. + +## **11.1 Configuration parameters** + +### **11.1.1 FEXT cancellation enable/disable** + +This configuration parameter shall be defined for each line in a group of vectored lines. It enables or disables FEXT cancellation from all the other vectored lines into a line in the vectored group. If FEXT cancellation is disabled for a line, then no FEXT cancellation shall occur from any other line in the vectored group into that line. + +This configuration parameter shall be defined independently for the upstream and downstream directions. + +### **11.1.2 FEXT cancellation not required frequency bands** + +This configuration parameter shall be an array of pairs of subcarrier indices. Each pair represents the start and stop subcarrier index of a frequency band in which FEXT cancellation is not required. Up to eight frequency bands may be configured. + +The same configuration shall be applied for all lines in the vectored group. + +This configuration parameter shall be defined independently for the upstream and downstream directions. + +### **11.1.3 Target NDR/target ETR** + +Both the target net data rate (target NDR) configuration parameter and the target expected throughput (target ETR) configuration parameter shall be defined for each line in a group of vectored lines. These configuration parameters assist a VCE to decide on allocating vectored AN resources among the lines in a vectored group for FEXT cancellation. Because of limited resources, the vectored AN may be unable to mitigate all the FEXT sources into every single line in the vectored group. Therefore, The VCE may choose to limit the number of crosstalk sources to cancel for each vectored line. + +#### **11.1.3.1 Target NDR** + +For each line, the target NDR configuration parameter should be set to the expected NDR achievable for the line when all lines in the vectored group are active and operating without ITU-T G.998.4 retransmission, or alternatively, it may be set to a special value indicating that no target NDR is configured by the operator. + +If the target NDR is configured by the operator and ITU-T G.998.4 retransmission is not selected during initialization for the applicable direction, the VCE should allocate sufficient resources in such a way that the NDR is higher than or equal to the target NDR. If at initialization time, the NDR is below the target NDR but above the minimum NDR (*net\_min*, see Annex K of [ITU-T G.993.2]), the VTU shall still transition to Showtime. + +This configuration parameter shall be defined independently for the upstream and downstream directions. + +This configuration parameter corresponds with the ITU-T G.997.1 parameter TARGET\_NDR (see clause 7.3.2.20.2 of [ITU-T G.997.1]) in the CO-MIB. + +#### 11.1.3.2 Target ETR + +For each line, the target ETR configuration parameter should be set to the expected ETR achievable for the line when all lines in the vectored group are active and operating with ITU-T G.998.4 retransmission, or alternatively, it may be set to a special value indicating that no target ETR is configured by the operator. + +If the target ETR is configured by the operator and ITU-T G.998.4 retransmission is selected during initialization for the applicable direction, the VCE should allocate sufficient resources in such a way that the ETR is higher than or equal to the target ETR. If at initialization time, the ETR is below the target ETR but above minimum ETR (*ETR\_min*, see clause 7 of [ITU-T G.998.4]), the VTU shall still transition to Showtime. + +This configuration parameter shall be defined independently for the upstream and downstream directions. + +This configuration parameter corresponds with the ITU-T G.997.1 parameter TARGET\_ETR (see clause 7.3.2.20.1 of [ITU-T G.997.1]) in the CO-MIB. + +### 11.1.4 Line priorities + +This configuration parameter assists a VCE to decide on allocating vectored AN resources among the lines in a vectored group for FEXT cancellation. Because of limited resources, the vectored AN may be unable to mitigate all the FEXT sources into every single line in the vectored group. Therefore, the VCE may choose to limit the number of crosstalk sources to cancel for each vectored line. + +Compliance with line priorities configuration parameter is optional. If supported, this configuration parameter shall be defined for each line in a group of vectored lines. For compliance, a VCE should initially allocate sufficient resources in such a way that the target NDR (if ITU-T G.998.4 retransmission is not selected for the applicable direction) or target ETR (if ITU-T G.998.4 retransmission is selected for the applicable direction) is met for all the lines in a vectored group. Subsequently, the VCE should exploit the configured line priority levels to allocate the remaining resources among the lines to further improve the NDRs/ETRs. + +For each line in the vectored group, the line priority is configured as either LOW or HIGH, or alternatively, it may be set to a special value indicating that no line priority is configured by the operator. The VCE should allocate more resources to a line with a line priority HIGH in order to further increase the NDR/ETR above the target NDR/target ETR (e.g., by further mitigating FEXT). The VCE should not allocate additional resources to a line with line priority HIGH if the maximum NDR (*net\_max*, see Annex K of [ITU-T G.993.2]) is already met on that line. If the maximum NDR condition is met for all the vectored lines with line priority HIGH, then the VCE may allocate its remaining resources to vectored lines with line priority LOW to improve the NDR/ETR above the target NDR/target ETR. + +NOTE – A VCE with sufficient resources may not need to use the configured line priorities for allocating its resources and in such cases, the VCE may ignore the configured line priorities. + +This configuration parameter shall be defined independently for the upstream and downstream directions. + +### 11.1.5 Requested Xlin subcarrier group size (XLINGREQ) + +This parameter represents the requested value of *XLING* (see clauses 11.2.1.2 and 11.2.2.2). The reported *XLING* value shall be the smallest supported value that is equal or greater than *XLINGREQ*. + +This configuration parameter shall be defined independently for the upstream and downstream directions. + +## 11.2 Test parameters + +### 11.2.1 FEXT downstream coupling coefficients (Xlinpsds) + +#### 11.2.1.1 Definition of downstream FEXT coupling coefficients (Xlinpsds) + +The FEXT insertion gain from line $L_2$ into line $L_1$ in the downstream direction over frequency $f$ , $FEXT\_IG\_DS_{L1,L2}(f)$ , is defined as the ratio of the received FEXT voltage into a 100-ohm load on line $L_1$ to the transmit voltage (into a 100-ohm load) on line $L_2$ . If the transmit voltage on line $L_2$ into a 100-ohm load is $V\_REFERENCE\_O(f)$ and the received FEXT voltage on line $L_1$ , while both ends are terminated with a 100-ohm load as shown in Figure 11-1, is $V\_FEXT\_R(f)$ , then the downstream FEXT insertion gain from line $L_2$ into line $L_1$ in linear scale is given by the equation below: + +$$FEXT\_IG\_DS_{L1,L2}(f) = \frac{V\_FEXT\_R(f)}{V\_REFERENCE\_O(f)}$$ + +The downstream FEXT coupling coefficient from line $L_2$ into line $L_1$ over the frequency $f$ is defined as the ratio of the FEXT insertion gain from line $L_2$ into line $L_1$ to the direct channel insertion gain of line $L_1$ (or the channel characteristic function, $H$ , of line $L_1$ ) as follows: + +$$Xlinds_{L1,L2}(f) = \frac{FEXT\_IG\_DS_{L1,L2}(f)}{H_{L1}(f)}$$ + +The downstream FEXT coupling coefficient can also be represented in terms of the direct channel $V\_DIRECT\_R(f)$ received on line $L_1$ , and the FEXT channel received voltage on line $L_1$ as: + +$$Xlinds_{L1,L2}(f) = \frac{V\_FEXT\_R(f)}{V\_DIRECT\_R(f)}$$ + +where, as shown in Figure 11-2, $V\_DIRECT\_R(f)$ is the received voltage into a 100-ohm load on line $L_1$ when a transmitter with a transmit voltage equal to $V\_REFERENCE\_O(f)$ (into 100 ohms) is frozen in its transmitting state and is connected to the same line. As shown in Figure 11-1, $V\_FEXT\_R(f)$ is the received voltage on line $L_1$ when this line is terminated with a 100-ohm load on both sides and the transmitter with the same transmit voltage is connected to line $L_2$ . + +NOTE 1 – The definition is independent of the value of $V\_REFERENCE\_O(f)$ . However, it should be of the same order as typical transmitting voltage values on the line. + +NOTE 2 – The above definition is independent of any receiver filter as the receiver filter effects of line $L_1$ are included in both the numerator and the denominator and cancel out. + +![Figure 11-1: Definition of downstream Xlin (FEXT channel received voltage). The diagram shows two horizontal lines representing transmission lines L1 and L2. Line L1 has a 100 Ω resistor at its left end and right end. A voltage V_FEXT_R is measured across the right 100 Ω resistor. Line L2 is below L1 and has a 100 Ω resistor at its right end. At the left end of L2, a 'Frozen transmitter' is connected to a voltage source V_s through a resistor R_s. A voltage V_REFERENCE_O is measured across the left end of L2.](f78d2e126f00fcc5d8d9797ca410cc09_img.jpg) + +Figure 11-1: Definition of downstream Xlin (FEXT channel received voltage). The diagram shows two horizontal lines representing transmission lines L1 and L2. Line L1 has a 100 Ω resistor at its left end and right end. A voltage V\_FEXT\_R is measured across the right 100 Ω resistor. Line L2 is below L1 and has a 100 Ω resistor at its right end. At the left end of L2, a 'Frozen transmitter' is connected to a voltage source V\_s through a resistor R\_s. A voltage V\_REFERENCE\_O is measured across the left end of L2. + +**Figure 11-1 – Definition of downstream Xlin (FEXT channel received voltage)** + +![Figure 11-2: Definition of downstream Xlin (direct channel received voltage). This diagram is similar to Figure 11-1 but with a different measurement point. Line L1 has a 100 Ω resistor at its right end. A voltage V_DIRECT_R is measured across this resistor. Line L2 is below L1 and has 100 Ω resistors at both its left and right ends. The 'Frozen transmitter' and voltage source V_s are connected to the left end of L2 through resistor R_s, with V_REFERENCE_O measured at the left end of L2.](cd3e29b6d40dce0580fa43b721157489_img.jpg) + +Figure 11-2: Definition of downstream Xlin (direct channel received voltage). This diagram is similar to Figure 11-1 but with a different measurement point. Line L1 has a 100 Ω resistor at its right end. A voltage V\_DIRECT\_R is measured across this resistor. Line L2 is below L1 and has 100 Ω resistors at both its left and right ends. The 'Frozen transmitter' and voltage source V\_s are connected to the left end of L2 through resistor R\_s, with V\_REFERENCE\_O measured at the left end of L2. + +**Figure 11-2 – Definition of downstream Xlin (direct channel received voltage)** + +#### 11.2.1.2 Reporting of downstream FEXT coupling coefficients (Xlinpsds) + +Each frequency band over which the downstream FEXT coupling coefficients $Xlinpsds_{i,k} (n \times \Delta f)$ are stored and reported shall be represented by a pair of (start\_subcarrier\_index, stop\_subcarrier\_index). The reported parameter *XLINBANDSds* shall represent an array of such pairs in increasing frequency order. + +NOTE – The start\_subcarrier\_index and stop\_subcarrier\_index may not coincide with the defined edges of the bandplan. + +The downstream FEXT coupling coefficients $Xlinpsds_{i,k} (n \times \Delta f)$ , shall be stored and reported to the management entity upon request at least for all pairs of line indices (*i*, *k*) in the vectored group and subcarrier indices *n* for which FEXT from line *k* into line *i* is estimated or cancelled in the downstream direction over a frequency band containing the subcarrier index *n* and + +$$n \in \bigcup_{\text{bands}} \{ \text{start\_subcarrier\_index} + m \times \text{XLINGds} : m = 0 \dots \lfloor (\text{stop\_subcarrier\_index} - \text{start\_subcarrier\_index}) / \text{XLINGds} \rfloor \}$$ + +where $\lfloor x \rfloor$ denotes rounding to the lower integer. + +In this description, *XLINGds* is the subcarrier group size for reporting the FEXT coupling and is restricted to powers of two, and shall be the smallest supported value that is equal to or greater than the *XLINGREQds* value (see clause 11.1.5) and less than or equal to 64, and shall be restricted to a maximum number of 511 subcarriers being reported. + +The channel characteristics function $Xlinpsds_{i,k} (n \times \Delta f)$ , shall be represented in linear format by a scale factor and a normalized complex number $a(n) + j \times b(n)$ , where *n* is the subcarrier index. The scale factor *XLINSCds* shall be coded as a 16-bit unsigned integer. Both *a(n)* and *b(n)* shall be coded as a 16-bit 2's-complement signed integers. The value of $Xlinpsus_{i,j} (n \times \Delta f)$ shall be defined as $Xlinpsus_{i,j} (n \times \Delta f) = (\text{XLINSCds}/2^{15}) \times (a(n) + j \times b(n))/2^{15}$ . In order to maximize precision, the *scale factor XLINSCds* shall be chosen such that $\max(|a(n)|, |b(n)|)$ over all *n* is equal to $2^{15} - 1$ . + +This data format supports an *Xlin(f)* granularity of $2^{-15}$ and an *Xlin(f)* dynamic range of approximately +6 dB to –90 dB. + +An $Xlinpsds_{i,j} (n \times \Delta f)$ value indicated as $a(n) = b(n) = -2^{15}$ is a special value. It indicates that no measurement could be done for done from line *k* into line *i* for subcarrier *n*. + +An $Xlinpsds_{i,j} (n \times \Delta f)$ value indicated with $a(n) \geq 0$ and $b(n) = 0$ for all reported $n$ is another special value meaning that there is no phase information and the magnitude of $Xlinpsus_{i,j} (n \times \Delta f)$ is $(XLINSCds/2^{15}) \times (a(n))/2^{15}$ . + +The magnitude of $Xlinpsds_{i,k} (n \times \Delta f)$ in dB is $Xlogpsds_{i,k} (n \times \Delta f)$ : + +$$Xlogpsus_{i,k} (n \times \Delta f) = 20 \log_{10} (|Xlinpsus_{i,k} (n \times \Delta f)|)$$ + +All accuracy requirements for $Xlinpsus$ will be formulated in terms of magnitude only ( $Xlogpsds$ ). + +Accuracy requirements for $Xlogpsds$ shall allow for $Xlogpsds$ to be the logarithm of the magnitude of the elements of the Taylor first-order approximation of the inverse of the pre-coder matrix (see Figure 6-1). Other accuracy requirements for $Xlogpsds$ are for further study. + +### 11.2.2 FEXT upstream coupling coefficients ( $Xlinpsus$ ) + +#### 11.2.2.1 Definition of upstream FEXT coupling coefficients ( $Xlinpsus$ ) + +The FEXT insertion gain from line $L_2$ into line $L_1$ in the upstream direction over the frequency $f$ , $FEXT\_IG\_US_{L1,L2}(f)$ , is defined as the ratio of the received FEXT voltage into a 100 ohm load on line $L_1$ to the transmit voltage (into a 100 ohm load) on line $L_2$ . If the transmit voltage on line $L_2$ into a 100 ohm load is $V\_REFERENCE\_R(f)$ and the received FEXT voltage on line $L_1$ , while both ends are terminated with 100 ohm load as is shown in Figure 11-3 is $V\_FEXT\_O(f)$ then the upstream FEXT insertion gain from line $L_2$ into line $L_1$ in linear scale is given by the equation below: + +$$FEXT\_IG\_US_{L1,L2}(f) = \frac{V\_FEXT\_O(f)}{V\_REFERENCE\_R(f)}$$ + +The upstream FEXT coupling coefficient from line $L_2$ into line $L_1$ over the frequency $f$ is defined as the ratio of the FEXT insertion gain from line $L_2$ into line $L_1$ to the direct channel insertion gain of line $L_2$ (or the channel characteristic function, $H$ , of line $L_2$ ) as in the following: + +$$Xlinus_{L1,L2}(f) = \frac{FEXT\_IG\_US_{L1,L2}(f)}{H_{L2}(f)}$$ + +The upstream FEXT coupling coefficient can also be represented in terms of the direct channel, $V\_DIRECT\_O(f)$ received on line $L_2$ and the FEXT channel received voltage on line $L_1$ as: + +$$Xlinus_{L1,L2}(f) = \frac{V\_FEXT\_O(f)}{V\_DIRECT\_O(f)}$$ + +where, as shown in Figure 11-4, $V\_DIRECT\_O(f)$ is the received voltage into a 100 ohm load on line $L_2$ when a transmitter with a transmit voltage equal to $V\_REFERENCE\_R(f)$ (into 100 ohm) is frozen in its transmitting state and is connected to the same line. As shown in Figure 11-3, $V\_FEXT\_O(f)$ is the received voltage on line $L_1$ when this line is terminated with 100 ohm loads on both sides and the transmitter with the same transmit voltage is connected to line $L_2$ . + +![Figure 11-3: Definition of upstream Xlin (FEXT channel received voltage). The diagram shows two transmission lines, L1 and L2. Line L1 is terminated with 100 Ω resistors at both ends and has a voltage V_FEXT_O measured across it. Line L2 is also terminated with 100 Ω resistors at both ends. At the right end of L2, there is a 'Frozen transmitter' connected to a voltage source V_s through a series resistor R_s. The voltage V_REFERENCE_R is measured at the right end of L2, between the line and the transmitter circuit. The diagram is labeled G.993.5(15)_F11-3.](24ba47df8be44ae91945d88ce2232df5_img.jpg) + +Figure 11-3: Definition of upstream Xlin (FEXT channel received voltage). The diagram shows two transmission lines, L1 and L2. Line L1 is terminated with 100 Ω resistors at both ends and has a voltage V\_FEXT\_O measured across it. Line L2 is also terminated with 100 Ω resistors at both ends. At the right end of L2, there is a 'Frozen transmitter' connected to a voltage source V\_s through a series resistor R\_s. The voltage V\_REFERENCE\_R is measured at the right end of L2, between the line and the transmitter circuit. The diagram is labeled G.993.5(15)\_F11-3. + +**Figure 11-3 – Definition of upstream Xlin (FEXT channel received voltage)** + +![Figure 11-4: Definition of upstream Xlin (direct channel received voltage). The diagram shows two transmission lines, L1 and L2. Line L1 is terminated with 100 Ω resistors at both ends and has a voltage V_DIRECT_O measured across it. Line L2 is also terminated with 100 Ω resistors at both ends. At the right end of L2, there is a 'Frozen transmitter' connected to a voltage source V_s through a series resistor R_s. The voltage V_REFERENCE_R is measured at the right end of L2, between the line and the transmitter circuit. The diagram is labeled G.993.5(15)_F11-4.](364054adcd1b427fa259450e006c6b38_img.jpg) + +Figure 11-4: Definition of upstream Xlin (direct channel received voltage). The diagram shows two transmission lines, L1 and L2. Line L1 is terminated with 100 Ω resistors at both ends and has a voltage V\_DIRECT\_O measured across it. Line L2 is also terminated with 100 Ω resistors at both ends. At the right end of L2, there is a 'Frozen transmitter' connected to a voltage source V\_s through a series resistor R\_s. The voltage V\_REFERENCE\_R is measured at the right end of L2, between the line and the transmitter circuit. The diagram is labeled G.993.5(15)\_F11-4. + +**Figure 11-4 – Definition of upstream Xlin (direct channel received voltage)** + +#### 11.2.2.2 Reporting of upstream FEXT coupling coefficients (Xlinpsus) + +Each frequency band over which the upstream FEXT coupling coefficients $Xlinpsus_{i,k} (n \times \Delta f)$ are stored and reported shall be represented by a pair of (start\_subcarrier\_index, stop\_subcarrier\_index). The reported parameter $XLINBANDSUs$ shall represent an array of such pairs in increasing frequency order. + +NOTE – The start\_subcarrier\_index and stop\_subcarrier\_index may not coincide with the defined edges of the bandplan. + +The upstream FEXT coupling coefficients, $Xlinpsus_{i,k} (n \times \Delta f)$ , shall be stored and reported to the management entity upon request at least for all pairs of line indices $(i, k)$ in the vectored group and subcarrier indices $n$ for which FEXT from line $k$ into line $i$ is estimated or cancelled in the upstream direction over a frequency band containing the subcarrier index $n$ and + +$$n \in \bigcup_{\text{bands}} \{ \text{start\_subcarrier\_index} + m \times XLINGus : m = 0 \dots \lfloor (\text{stop\_subcarrier\_index} - \text{start\_subcarrier\_index}) / XLINGus \rfloor \}$$ + +where $\lfloor x \rfloor$ denotes rounding to the lower integer. + +In this description, $XLINGus$ is the subcarrier group size for reporting the FEXT coupling and is restricted to powers of two, equal to or greater than the $XLINGREQus$ value (see clause 11.1.5) and less than or equal to 64, and restricted to a maximum number of 511 subcarriers being reported. + +The channel characteristics function $Xlinpsus_{i,k} (n \times \Delta f)$ , shall be represented in linear format by a scale factor and a normalized complex number $a(n) + j \times b(n)$ , where $n$ is the subcarrier index. The scale factor $XLINSCus$ shall be coded as a 16-bit unsigned integer. Both $a(n)$ and $b(n)$ shall be coded as a 16-bit 2's-complement signed integers. The value of $Xlinpsus_{i,j} (n \times \Delta f)$ shall be defined as $Xlinpsus_{i,j} (n \times \Delta f) = (XLINSCus/2^{15}) \times (a(n) + j \times b(n))/2^{15}$ . In order to maximize precision, the scale factor $XLINSCus$ shall be chosen such that $\max(|a(n)|, |b(n)|)$ over all reported $n$ is equal to $2^{15} - 1$ . + +This data format supports an $Xlin(f)$ granularity of $2^{-15}$ and an $Xlin(f)$ dynamic range of approximately +6 dB to -90 dB. + +An $Xlinpsus_{i,j} (n \times \Delta f)$ value indicated as $a(n) = b(n) = -2^{15}$ is a special value. It indicates that no measurement could be done for done from line $k$ into line $i$ for subcarrier $n$ . + +An $Xlinpsus_{i,j} (n \times \Delta f)$ value indicated with $a(n) \geq 0$ and $b(n) = 0$ for all reported $n$ is another special value meaning that there is no phase information and the magnitude of $Xlinpsus_{i,j} (n \times \Delta f)$ is the magnitude of $a(n)$ . + +The magnitude of $Xlinpsus_{i,k} (n \times \Delta f)$ in dB is $Xlogpsus_{i,k} (n \times \Delta f)$ : + +$$Xlogpsus_{i,k} (n \times \Delta f) = 20 \log_{10} (|Xlinpsus_{i,k} (n \times \Delta f)|)$$ + +All accuracy requirements for $Xlinpsus$ shall be formulated in terms of magnitude only ( $Xlogpsus$ ) and are for further study. + +# Annex A + +## Mitigating strong FEXT + +(This annex forms an integral part of this Recommendation.) + +## A.1 Introduction + +This annex defines a method for mitigating strong FEXT. + +This annex is an optional functionality, only applicable if the VTU is operating according to Annex Q of [ITU-T G.993.2]. + +The functionality defined in this annex includes: + +- transmitter initiated gain adjustment for VDSL2 transceiver (TIGAV) procedure; +- use of extended error clipping threshold. + +## A.2 Control parameters for the minimum message overhead data rate (amends clause 9.5.4 of [ITU-T G.993.2]) + +For operation according to this annex, the downstream $msg_{min}$ and the upstream $msg_{min}$ control parameters shall be derived from the MSGMINd and MSGMINu configuration parameters (defined in the CO-MIB, see clause 7.3.1.5 of [ITU-T G.997.1]) respectively, as follows: + +- for profile 35b: + - downstream: $\max(\text{MSGMINd}, 200 \text{ kbit/s}) \leq msg_{min} \leq 236 \text{ kbit/s}$ ; + - upstream: $\max(\text{MSGMINu}, 64 \text{ kbit/s}) \leq msg_{min} \leq 236 \text{ kbit/s}$ ; +- for profile 17a: + - downstream: $\max(\text{MSGMINd}, 64 \text{ kbit/s}) \leq msg_{min} \leq 236 \text{ kbit/s}$ ; + - upstream: $\max(\text{MSGMINu}, 64 \text{ kbit/s}) \leq msg_{min} \leq 236 \text{ kbit/s}$ ; + +## A.3 Clipped error samples + +### A.3.1 Definition of clipped error sample (replaces clause 3.2.4) + +**clipped error sample:** Is a normalized error sample that is further clipped by the VTU-R with control from the VCE (see clause A.3.3). + +### A.3.2 Control parameters for clipped error sample reporting (amends clause 7.2.2.1) + +For operation according to this annex, Table A.1 defines an additional mandatory value for the clipped error samples control parameters, in addition to the values in Table 7-2. This value is defined for the VCE to configure and for the VTU-O and VTU-R to support. + +**Table A.1 – Additional values of backchannel control parameters** + +| Parameter | Additional valid value for VCE | Additional mandatory value for VTU-O and VTU-R | +|-----------|--------------------------------|------------------------------------------------| +| $B_{max}$ | 13 | 13 | + +### A.3.3 Definition of normalized error sample (amends clause 7.2.1) + +For all values of $B\_max$ , the normalized error sample shall be as defined in clause 7.2.1. + +The real and imaginary components of each normalized error sample $E$ shall be clipped and quantized to integer values for the clipped error sample components $q\_x$ and $q\_y$ respectively, as follows: + +$$\begin{aligned} \text{for } B\_max \leq 11: \quad & q\_x = \max\left(-2^{B\_max}, \min\left(\left\lfloor e\_x \times 2^{N\_max-1} \right\rfloor, 2^{B\_max} - 1\right)\right) \\ & q\_y = \max\left(-2^{B\_max}, \min\left(\left\lfloor e\_y \times 2^{N\_max-1} \right\rfloor, 2^{B\_max} - 1\right)\right) \\ \text{for } B\_max = 13: \quad & q\_x = \max\left(-CT, \min\left(\left\lfloor e\_x \times 2^{N\_max-1} \right\rfloor, CT - 1\right)\right) \\ & q\_y = \max\left(-CT, \min\left(\left\lfloor e\_y \times 2^{N\_max-1} \right\rfloor, CT - 1\right)\right) \end{aligned}$$ + +where $Q = q\_x + j \times q\_y$ represents the clipped error sample and $N\_max$ represents the VTU-R's maximum quantization depth of normalized error samples and shall be set to 12, and $B\_max$ represents the upper bound of the bit index for reporting clipped error sample components $q\_x$ and $q\_y$ ( $B\_max < N\_max$ , with $B\_max$ configured by the VCE, see Tables 7-1 and 7-2). + +For the case $B\_max = 13$ , the parameter $CT$ represents the clipping threshold, which is a vendor discretionary value that shall be within the interval $[2^{B\_max} - 2^{(N\_max-1)}, 2^{B\_max}]$ . The value of $CT$ shall be determined by the VTU-R during initialization before sending the R-ERROR-FEEDBACK message, and shall remain identical for the remainder of initialization and the subsequent showtime (see Notes 1 and 2). + +NOTE 1 – Referring to the scaling shown in Figure 7-3, the equivalent clipping intervals for $e\_x$ and $e\_y$ are: + +$$\text{for } B\_max \leq 11: \quad \left[ -\left( \frac{2^{B\_max}}{2^{(N\_max-1)}} \right), \left( \frac{2^{B\_max} - 1}{2^{(N\_max-1)}} \right) \right], \text{ which approximately equals } [-1, 1) \text{ for } B\_max = 11;$$ + +$$\text{for } B\_max = 13: \quad \left[ -\frac{CT}{2^{(N\_max-1)}}, \frac{CT - 1}{2^{(N\_max-1)}} \right], \text{ with } \frac{CT}{2^{(N\_max-1)}} \text{ in the interval } [3, 4], \text{ which}$$ + +approximately equals $[-3, 3)$ for $CT = (2^{B\_max} - 2^{(N\_max-1)})$ . + +NOTE 2 – For $B\_max = 13$ , no vendor discretionary clipping is allowed for error samples within the range of $[-(2^{B\_max} - 2^{(N\_max-1)}), (2^{B\_max} - 2^{(N\_max-1)}) - 1]$ . + +For all values of $B\_max$ , the values of both clipped error sample components $q\_x$ and $q\_y$ shall be represented using the two's-complement representation of $B\_max+1$ bits. The format of the clipped error sample for reporting over the backchannel is defined in clause 7.2.2. The particular subcarriers on which clipped error samples shall be reported during initialization and Showtime shall be configured as described in clauses 10.4.2.1, and in clause 8.1, respectively. + +## A.4 OLR commands + +The VTU shall support OLR commands to facilitate operation of vectored lines according to this annex, (see Table A.2). + +**Table A.2 – OLR commands and responses** + +| Command type | Direction of command | Command content | Response content | +|--------------------------------|----------------------|------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------| +| OLR request type 7 (TIGAV) | From VTU-O to VTU-R | The relative gain compensation factor ( $r_i$ ) and the proposed bit loading ( $b_i$ ) to be applied to a set of downstream subcarriers. | TIGAV-ACK response or TIGAV-Reject response | +| OLR request type 8 (TIGAVRESP) | From VTU-R to VTU-O | The bit loading ( $b_i$ ) to be applied to the relevant set of downstream subcarriers and framing parameters. | TIGAVRESP-ACK response or TIGAVRESP-Reject response | + +## **A.5 ITU-T G.994.1 Handshake phase (amends clause 10.2)** + +The functionality defined in this annex shall be negotiated during the ITU-T G.994.1 Handshake phase of initialization, using the NPar(3) codepoint defined in Table 11.68.10.1 of [ITU-T G.994.1]. The use of this codepoint in the ITU-T G.994.1 CL, CLR and MS messages is defined in Tables A.3 to A.6. + +**Table A.3 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of strong FEXT mitigation | If set to ONE, this bit indicates that the VTU-O supports the functionality defined in this annex. If set to ZERO, this bit indicates that the VTU-O does not support the functionality defined in this annex. | + +**Table A.4 – VTU-O MS message NPar(3) bit definitions** + +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of strong FEXT mitigation | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message, and a profile is selected to which this annex applies. If set to ONE, this bit indicates that the functionality defined in this annex is enabled. If set to ZERO, this bit indicates that the functionality defined in this annex is disabled. | + +**Table A.5 – VTU-R CLR message NPar(3) bit definitions** + +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +|----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Suport of strong FEXT mitigation | If set to ONE, this bit indicates that the VTU-R supports the functionality defined in this Annex. If set to ZERO, this bit indicates that the VTU-R does not support the functionality defined in this annex. | + +**Table A.6 – VTU-R MS message NPar(3) bit definitions** + +| ITU-T G.994.1 NPar(3) Bit | Definition of NPar(3) bits | +|-----------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of strong FEXT mitigation | This bit shall be set to ONE if, and only if, it was set to ONE in both the last previous CL message and the last previous CLR message, and a profile is selected to which this annex applies. If set to ONE, this bit indicates that the functionality defined in this annex is enabled. If set to ZERO, this bit indicates that the functionality defined in this annex is disabled. | + +If the ITU-T G.994.1 CLR message has the "Support of strong FEXT mitigation" Npar(3) bit set to ONE, then it shall indicate support for profile 35b and may indicate support for any other profile. + +If the ITU-T G.994.1 CL message has the "Support of strong FEXT mitigation" Npar(3) bit set to ONE and the profile 35b is enabled in the CO-MIB, then it shall indicate support for profile 35b and may indicate support for any other profile. + +If the ITU-T G.994.1 MS message has the "Support of strong FEXT mitigation" Npar(3) bit set to ONE, then it shall operate according to Annex Q of [ITU-T G.993.2] and select operation according to either profile 17a or profile 35b. + +## A.6 TIGAV functionality + +The functionality associated with TIGAV procedure shall be supported by both the VTU-O and the VTU-R. + +The goal of the procedure is fast accommodation of precoder changes in high crosstalk environment by indicating to the VTU-R the associated changes of compensation gain and expected changes of bit loading on relevant downstream subcarriers. + +The VTU-O starts the procedure by sending a TIGAV command to the VTU-R that indicates the relative gain compensation factor ( $r_i$ ) and the proposed bit loading ( $b_i$ ) to be applied to the indicated set of downstream subcarriers. In response, based on the received $r_i$ values, the VTU-R computes the actual downstream bit loading and sends it back to the VTU-O in TIGAVRESP command. Further, the VTU-O sends to the VTU-R a time marker indicating the symbol position at which the new values of $r_i$ are applied by the VTU-R and the actual $b_i$ values requested by the VTU-R are applied by both VTUs. The details of the message exchange are in clause A.6.2. + +The VTU-R may either accept the actual bit loading to be as proposed in the TIGAV command, or request the actual bit loading to be different. In the latter case, the actual bit loading requested by the VTU-R in the TIGAVRESP shall follow the rules defined in clause A.6.1.2. + +### A.6.1 TIGAV and TIGAVRESP commands + +The TIGAV and TIGAVRESP are OLR commands and shall be used to facilitate the TIGAV procedure. Both commands are high priority; the first octets of commands and associated responses shall be an OLR commands type defined in Table 11-2 of [ITU-T G.993.2]. The subsequent octets of the commands shall be as defined in Table A.7. The subsequent octets of the responses shall be as defined in Table A.8. The octets of all commands and responses shall be sent using the format described in clause 11.2.3.1 of [ITU-T G.993.2]. Message segmentation shall be applied as defined in clause 11.2.3.3 of [ITU-T G.993.2]. + +The TIGAV command shall be sent by the VTU-O only. + +The TIGAVRESP command shall be sent by the VTU-R only. + +The 4-bit TIGAV identification number (TID) is used to identify the particular TIGAV command. The TID shall be incremented whenever a TIGAV containing a new set of parameters is initiated by the VTU-O and wrap around at count $1111_2$ , i.e., incrementing from $1111_2$ to $0000_2$ . + +The VTU-R shall indicate in the TIGAVRESP command the same TID value as indicated by the VTU-O in the corresponding TIGAV command. + +**Table A.7 – TIGAV and TIGAVRESP commands** + +| Name | Length (bytes) | Octet number | Content | Support | +|-------------------------------------|----------------|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| Request Type 7 (TIGAV) | Variable | 2 | 10 16 (Note 1) | Mandatory | +| | | 3 | The four MSBs represent the TID (with valid range 0 to 15, represented as unsigned integer).
The four LSBs represent the number of subcarrier band parameter subfields ( $1 \leq N_{scbt} \leq 15$ , represented as unsigned integer). | | +| | | Variable | Subcarrier bands parameter field, includes $N_{scbt}$ subcarrier band parameter subfields, see Table A.10. | | +| | | Variable | 1 octet for Segment Code (SC) | | +| Request Type 8 (TIGAVRESP) (Note 2) | Variable | 2 | 11 16 (Note 1) | Mandatory | +| | | 3-4 | two octets containing the new value for $L_1$ | | +| | | 5 | one octet containing the new value for $B_{10}$ | | +| | | 6 | one octet containing the new value for $M_1$ | | +| | | 7 | one octet containing the new value for $R_1$ | | +| | | 8 | one octet containing the new value for $Q$ | | +| | | 9 | one octet containing the new value for $V$ | | +| | | 10 | one octet containing the new value for $Q_{tx}$ | | +| | | 11 | one octet containing the new value for $lb$ | | +| | | 12 | The four MSBs represent the TID (with valid range 0 to 15, represented as unsigned integer).
The four LSBs represent the number of subcarrier band parameter subfields ( $0 \leq N_{scbr} \leq 15$ , represented as unsigned integer).
$N_{scbr} = 0$ : Accept the TIGAV proposed bit loading.
$N_{scbr} > 0$ : Response with the bit loading values requested by the VTU-R, indicated in the subcarrier bands parameter field. | | +| | | Variable | Subcarrier bands parameter field, includes $N_{scbr}$ subcarrier band parameter subfields, (see Table A.14). If $N_{scbr}=0$ , the length of this field shall be 0 bytes. | | +| | | Variable | 1 octet for Segment Code (SC) | | + +NOTE 1 – All other values are reserved by ITU-T. + +NOTE 2 – The framing parameters in octets 3 to 11 shall be represented as defined for request type 5 in clause C.3.2 of [ITU-T G.998.4]. + +The TIGAV-Reject and TIGAV-ACK, and TIGAVRESP-Reject and TIGAVRESP-ACK, are responses on TIGAV and TIGAVRESP commands, respectively (see Table A.8). The reason codes for the reject responses are defined in Table A.9. + +The TIGAV-Reject and TIGAV-ACK responses shall be sent by the VTU-R only. + +The TIGAVRESP-Reject and TIGAVRESP-ACK responses shall be sent by VTU-O only. + +**Table A.8 – TIGAV and TIGAVRESP responses** + +| Name | Length (octets) | Octet number | Content | Support | +|------------------------------------------|-----------------|--------------|-------------------------|-----------| +| Reject Type 7 request (TIGAV-Reject) | 3 | 2 | 87 16 (Note) | Mandatory | +| | | 3 | 1 octet for reason code | | +| ACK Type 7 request (TIGAV-ACK) | 2 | 2 | 89 16 (Note) | Mandatory | +| Reject Type 8 request (TIGAVRESP-Reject) | 3 | 2 | 88 16 (Note) | Mandatory | +| | | 3 | 1 octet for reason code | | +| ACK Type 8 request (TIGAVRESP-ACK) | 2 | 2 | 8A 16 (Note) | Mandatory | + +NOTE – All other values are reserved by ITU-T. + +**Table A.9 – Reason codes for TIGAV and TIGAVRESP responses** + +| Reason | Octet value | Applicable to Reject Type 7 | Applicable to Reject Type 8 | +|--------------------|-------------------------|-----------------------------|-----------------------------| +| Busy | 01 16 (Note) | No | Yes | +| Invalid parameters | 02 16 (Note) | Yes | Yes | + +NOTE – All other values are reserved by ITU-T. + +#### A.6.1.1 Parameters of the TIGAV command + +The subcarrier bands parameter field in the TIGAV command includes $N_{scbt}$ subcarrier band parameter subfields. The format of each subcarrier band parameter subfield is defined in Table A.10. + +Each of the subcarrier band parameter subfields identifies one TIGAV band. A TIGAV band is delimited by its *i\_start* and *i\_stop* subcarrier indices: + +- The *i\_start* may fall on an active or on an inactive subcarrier (i.e., $g_i=0$ ). The *i\_stop* may fall on an active or on an inactive subcarrier (i.e., $g_i=0$ ). There may also be inactive subcarriers within a TIGAV band. +- The *i\_start* and *i\_stop* determine the grid of control subcarrier indices for the "*ri*" interpolation (see clause A.6.1.3) as: + +$$i = i\_start + k \times F\_sub\_TIGAV, \text{ where } k = 0, 1, 2, \dots (N_r - 1),$$ + +with a constraint: $i\_stop = i\_start + (N_r - 1) \times F\_sub\_TIGAV$ , where $N_r$ is an integer larger than 1, and $F\_sub\_TIGAV$ is the applied *ri* sub-sampling, as defined in Table A.10. + +- The *i\_start* and *i\_stop* indices shall satisfy: + +$$\begin{aligned} i\_start &> i\_start\_DSx - F\_sub\_TIGAV, \\ i\_stop &< i\_stop\_DSx + F\_sub\_TIGAV, \end{aligned}$$ + +where *i\_start\_DSx* and *i\_stop\_DSx* are respectively the minimum and the maximum subcarrier index that belong to the particular downstream passband (see clause 7.1 of [ITU-T G.993.2]). + +NOTE – This allows freedom in choosing the location of TIGAV control point grid. + +- The *i\_start* and *i\_stop* are independent from the MEDLEYds set, i.e., *i\_start* can be smaller than, equal to, or larger than the minimum subcarrier index of MEDLEYds set and *i\_stop* can be smaller than, equal to, or larger than the maximum subcarrier index of MEDLEYds set, respectively. + +- The *i\_start* and *i\_stop* are independent from the vectored bands (as exchanged in the *vectored bands* field of the Error Feedback Command defined in Table 8-3). + +For each particular TIGAV band *n*, followed by TIGAV band *n*+1 (*n* = 1 to *Nscbt* – 1): + +- The *i\_stop(n)* shall be less than or equal to *i\_start(n+1)*, i.e., no or one common index; +- If *i\_stop(n)* = *i\_start(n+1)* (i.e., one common index), the *ri* and *bi* values shall satisfy following constraints: *r(i\_stop(n))* = *r(i\_start(n+1))* and *b(i\_stop(n))* = *b(i\_start(n+1))*. + +Both inactive and active subcarriers may exist outside the TIGAV bands. On these active subcarriers, the VTU-R shall assume an *ri* = 1 (i.e., FEQ will not be affected by TIGAV) and shall assume no change in *bi*. + +TIGAV bands shall be transmitted in the ascending order of their intervals of subcarrier indices. + +**Table A.10 – Subcarrier band parameter subfield of the TIGAV command** + +| Parameter | Length (byte) | Definition | +|-----------------------------------------------------------------------------------------------|------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Control byte | 1 | [c000 ffff]
Control bit c = 0 indicates that this subfield contains real ri parameters (see Note 2).
Control bit c = 1 indicates that this subfield contains complex ri parameters (see Note 2).
Control bits ffff = F_sub_TIGAV for this subfield, represented as unsigned integer. | +| i_start | 2 | TIGAV band start subcarrier index ( i_start ), represented as a 16-bit unsigned integer. | +| i_stop | 2 | TIGAV band stop subcarrier index ( i_stop ), represented as a 16-bit unsigned integer. | +| bi | $\text{ceil}(N_b / 2)$
(Note 1) | This field contains Nb TIGAV bi parameters (see Table A.11) for subcarriers with indices i_start to i_stop , in ascending order of subcarrier indices. | +| real ri | 2× Nr | This field is present if and only if the control bit c = 0.
This field contains Nr TIGAV real ri parameters (see Table A.13) for subcarriers with index i_start + k × F_sub_TIGAV , with k = 0 to Nr – 1, in ascending order of subcarrier indices. | +| complex ri | 3× Nr | This field is present if and only if the control bit c = 1.
This field contains Nr TIGAV complex ri parameters (see Table A.12) for subcarriers with index i_start + k × F_sub_TIGAV , with k = 0 to Nr – 1, in ascending order of subcarrier indices. | +| NOTE 1 – $N_b = i\_stop - i\_start + 1$ . | | | +| NOTE 2 – The bit c shall be set to the same value in all subcarrier band parameter subfields. | | | + +The valid values for *F\_sub\_TIGAV* are 1, 4, and 8 (i.e., the *ri* values may be subsampled). + +Both VTU-O and VTU-R shall support all valid values for *i\_start*, *i\_stop*, and *F\_sub\_TIGAV*. + +**Table A.11 – The $b_i$ parameter format in a TIGAV command** + +| Bit | Length (bits) | Parameter (see Notes 1 and 2) | Format | +|-----|---------------|-------------------------------|--------------------------------------| +| 3-0 | 4 | $b_i$ (of subcarrier $k$ ) | Unsigned integer in the [0:15] range | +| 7-4 | 4 | $b_i$ (of subcarrier $k+1$ ) | Unsigned integer in the [0:15] range | + +NOTE 1 – The values of $b_i$ for subcarriers that are in the specified range (i.e., from $i\_start$ to $i\_stop$ ) but not part of the MEDLEYds set shall be included. They shall be set to zero by the transmitter and ignored by the receiver. + +NOTE 2 – If the $N_b$ is odd, the bits 7-4 of the $b_i$ parameter associated with the highest subcarrier index shall be set to 00002. + +**Table A.12 – The complex $r_i$ parameter format of the TIGAV command** + +| Bit | Length (bits) | Content (see Notes 1 and 2) | Format | +|-------|---------------|-------------------------------------|-----------------------| +| 2-0 | 3 | Exponent of $r_i$ | E3/4 | +| 12-3 | 10 | Mantissa of real part of $r_i$ | M10(1Q9) signed | +| 22-13 | 10 | Mantissa of imaginary part of $r_i$ | M10(1Q9) signed | +| 23 | 1 | Reserved by ITU-T | Bit shall be set to 0 | + +NOTE 1 – The values of $r_i$ for subcarriers that are in the specified range (i.e., from $i\_start$ to $i\_stop$ ), but not part of the MEDLEYds set are set to a vendor discretionary non-zero value. + +NOTE 2 – The byte transmitted first shall contain bits 23(MSB) to 16(LSB). The byte transmitted second shall contain bits 15(MSB) to 8(LSB). The byte transmitted third shall contain bits 7(MSB) to 0(LSB). + +The format descriptor L M ML(iQf) E LE/B designates a floating point format with total wordlength L. It has mantissa wordlength of ML bits, with the binary point just to the right of the i-th most significant bit (including the sign bit if signed integer), and f bits are allocated behind the binary point (i.e., ML=i+f). The exponent is always unsigned and has wordlength LE. The exponent has unity gain when its value equals B. Letters M, Q and E are syntax-separators. + +The real and imaginary part of the complex gain $r_i$ value shall both be formatted as 13M10(1Q9) E3/4 with a signed mantissa, and a common exponent. + +A non-zero complex $r_i$ value shall be within the valid range expressed in dB as: + +$$-18 \text{ dB} < 20 \times \log_{10}(\text{abs}(r_i)) < +18 \text{ dB},$$ + +where $\text{abs}(x)$ is the modulus of a complex value $x$ . + +A special value of complex $r_i$ is $r_i = 0$ , which shall be coded with a mantissa=0 and exponent=0, for both real and imaginary part, and shall be accompanied with $b_i = 0$ . + +**Table A.13 – The real $r_i$ parameter format of the TIGAV command** + +| Bit | Length (bits) | Content (see Notes 1 and 2) | Format | +|-------|---------------|-----------------------------|-------------------------------| +| 2-0 | 3 | Exponent of $r_i$ | E3/4 | +| 12-3 | 9 | Mantissa of $r_i$ | M9(0Q9) unsigned (see Note 3) | +| 15-12 | 4 | Reserved by ITU-T | Bits shall be set to 0 | + +NOTE 1 – The values of $r_i$ for subcarriers that are in the specified range (i.e., from $i\_start$ to $i\_stop$ ), but not part of the MEDLEYds set are set to a vendor discretionary non-zero value. + +NOTE 2 – The byte transmitted first shall contain bits 15(MSB) to 8(LSB). The byte transmitted second shall contain bits 7(MSB) to 0(LSB). + +NOTE 3 – Real $r_i$ values shall be positive values only. + +A real $r_i$ value shall be formatted as floating point 12M9(0Q9) E3/4 unsigned. + +A non-zero real $r_i$ value shall be within the valid range expressed in dB as: + +$$-18 \text{ dB} < 20 \times \log_{10} (r_i) < +18 \text{ dB}.$$ + +A special value of real $r_i$ is $r_i = 0$ , which shall be coded with a mantissa=0 and exponent=0, and shall be accompanied with $b_i = 0$ . + +NOTE – The TIGAV procedure does not change the downstream $g_i$ -values. The changes in the transmit power of the downstream subcarriers associated with TIGAV is achieved by corresponding modification of the precoder. + +#### A.6.1.2 Parameters controlled by the TIGAVRESP command + +The subcarrier bands parameter field in TIGAVRESP command includes $N_{scbr}$ subcarrier band parameter subfields. The format of each subcarrier band parameter subfield is defined in Table A.14. + +Each of the subcarrier band parameter subfields identifies one TIGAVRESP band. The TIGAVRESP bands in the TIGAVRESP command shall follow the same requirements as defined for the TIGAV bands in the TIGAV command in clause A.6.1.1, and the following additional requirements: + +- 1) The $N_{scbt}$ is replaced with $N_{scbr}$ . +- 2) If $N_{scbr}$ is set to a non-zero value in TIGAVRESP command, the TIGAVRESP bands in TIGAVRESP command shall include at least all MEDLEY subcarriers addressed by the corresponding TIGAV command. +- 3) The $b_i$ values requested by TIGAVRESP command for all MEDLEY subcarriers addressed by corresponding TIGAV command shall not exceed the $b_i$ values proposed by the TIGAV command. In addition to this mandatory upper limit, the actual bit loading in the TIGAVRESP should be upper limited by the bit loading that is based on the change in the SNR expected from the new values of $r_i$ , and might be upper limited by other factors. +- 4) If TIGAVRESP bands in TIGAVRESP command include more MEDLEY subcarriers than the corresponding TIGAV command, the $b_i$ values on these additional MEDLEY subcarriers are determined solely by the VTU-R. + +**Table A.14 – Subcarrier band parameter subfield in a TIGAVRESP command** + +| Parameter | Length (byte) | Definition | +|-----------------------------------------|----------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $i\_start$ | 2 | TIGAVRESP band start subcarrier index ( $i\_start$ ), represented as a 16-bit unsigned integer. | +| $i\_stop$ | 2 | TIGAVRESP band stop subcarrier index ( $i\_stop$ ), represented as a 16-bit unsigned integer. | +| $b_i$ | $\text{ceil}(N_b / 2)$
(Note) | This field contains $N_b$ TIGAVRESP $b_i$ parameters (see Table A.15) for subcarriers with indices $i\_start$ to $i\_stop$ , in ascending order of subcarrier indices. | +| NOTE – $N_b = i\_stop - i\_start + 1$ . | | | + +**Table A.15 – The $b_i$ parameter format in a TIGAVRESP command** + +| Bit | Length (bits) | Parameter
(see Notes 1, 2 and 3) | Format | +|-----|---------------|-------------------------------------|--------------------------------------| +| 3-0 | 4 | $b_i$ (of subcarrier k) | Unsigned integer in the [0:15] range | +| 7-4 | 4 | $b_i$ (of subcarrier k+1) | Unsigned integer in the [0:15] range | + +NOTE 1 – The values of $b_i$ for subcarriers that are in the specified range (i.e., from $i\_start$ to $i\_stop$ ), but not part of the MEDLEY set, shall be included. They shall be set to zero by the transmitter and ignored by the receiver. + +NOTE 2 – The values of $b_i$ shall be transmitted in ascending order of the subcarrier indices. + +NOTE 3 – If the $N_b$ is odd, the bits 7-4 of the $b_i$ parameter associated with the highest subcarrier index shall be set to 00002. + +#### A.6.1.3 Interpolation of the $r_i$ values + +For each particular TIGAV band $n$ ( $n=1$ to $N_{scbl}$ ), the VTU-R should derive the $r_i$ values on all active subcarriers between $i\_start(n)$ and $i\_stop(n)$ (both inclusive), by linear interpolation in between the $r_i$ values at the control subcarrier indices communicated in the TIGAV message. Linear interpolation shall be on a linear scale over the $r_i$ axis and a linear scale over the index axis. + +NOTE 1 – The VCE should choose the $r_i$ values in a TIGAV command such that the linear interpolation at the VTU-R produces the desired output values on intermediate active subcarriers. The method to define these $r_i$ values (control points) is VCE vendor discretionary. + +NOTE 2 – The $i\_start$ and $i\_stop$ are allowed to fall on an inactive subcarrier. The VCE should choose the $r_i$ values on $i\_start$ and $i\_stop$ in a TIGAV command such that the linear interpolation at the VTU-R produces the desired output values on intermediate active subcarriers. + +NOTE 3 – The inactive subcarriers included in a TIGAV are known by the VTU-R. The VTU-R does not need to calculate the interpolation on these carriers. + +### A.6.2 TIGAV procedure + +The VTU-O shall not initiate a TIGAV if either an upstream or a downstream save our showtime (SOS) type 4 or 6 procedure is ongoing. + +The exchange between VTUs in the TIGAV procedure is illustrated in Figure A.1 and defined as follows: + +- 1) Upon the instruction of the VCE over the $\epsilon\_m$ interface, the VTU-O shall initiate a TIGAV procedure by sending an OLR request type 7 command. A TIGAV command may be segmented. After sending the last segment of the TIGAV command, during the following 100 ms the VTU-O shall expect to receive the TIGAV-ACK response or a TIGAV-Reject response. The last segment of the TIGAV command may be repeated if the response times out. + - a) If the VTU-O receives an OLR request type 1, 3 and 5 during or after transmission of an OLR request type 7 and prior to receiving a response, it shall reject the OLR request type 1, 3 and 5 (see Note 1). + - b) If the VTU-O receives an SOS OLR request type 4 or 6 during the TIGAV procedure, it shall abort the TIGAV procedure immediately and respond to the OLR SOS request. + - c) The VTU-O is allowed to initiate an SOS OLR request type 4 or 6 procedure at any time after the TIGAV is initiated but not completed. The initiated SOS request shall abort the TIGAV procedure (see Notes 2 and 3). + +NOTE 1 – It is expected that in the aim to speed up starting TIGAV, the VTU-O may discard any pending SRA request because the modification of transmission parameters implied by this request will anyway be overridden by TIGAV. + +NOTE 2 – Termination of the TIGAV procedure due to SOS OLR request is only for the line in which the SOS request takes place; other lines in the vectored group can continue their TIGAV procedures. + +NOTE 3 – Clause 11.2.2 of [ITU-T G.993.2] describes the possibility of a high priority message aborting a low priority message. This TIGAV abort by an SOS is a case when a high priority message is aborted by another high priority message, and is therefore an extension to clause 11.2.2 of [ITU-T G.993.2]. + +- 2) After reception of the last segment of a TIGAV command, the VTU-R shall either acknowledge the TIGAV command by sending the TIGAV-ACK response (see Table A.7) or reject the TIGAV command by sending a TIGAV-Reject response with a corresponding reason code. + - a) Upon receiving the first segment of a TIGAV command, the VTU-R shall reject any pending OLR command of type 1, 3 and 5 and shall not initiate any OLR request type 1, 3 and 5 procedure until the TIGAV procedure is complete. + - b) Upon receiving an SOS OLR request type 4 or 6 from the VTU-O at any time during the TIGAV procedure, it shall abort the TIGAV procedure immediately and respond to the OLR SOS request. + - c) The VTU-R is allowed to initiate an SOS OLR request type 4 or 6 procedure at any time after the TIGAV is initiated but before the start of sending the last segment of TIGAVRESP. The changes in bit loading contained in the SOS request shall be applied to the current active bit loading table (i.e., ignoring the bit loading sent in TIGAV). This initiated SOS request shall abort the TIGAV procedure. The VTU-O shall respond to the SOS OLR request with a SYNC FLAG. + - d) The VTU-R shall not initiate an SOS OLR request type 4 or 6 procedure after the start of sending the last segment of TIGAVRESP up until the end of the TIGAV procedure. +- 3) Within 300 ms after sending the TIGAV-ACK response, the VTU-R shall send a TIGAVRESP command. A TIGAVRESP command may be segmented. After sending the last segment of the TIGAVRESP command, during the following 100 ms the VTU-R shall expect receiving a TIGAVRESP-ACK response or a TIGAVRESP-Reject response. If the last segment of the TIGAVRESP command times out, the VTU-R shall repeat the last segment of the TIGAVRESP command. After sending the TIGAV-Reject response, the VTU-R shall exit the TIGAV procedure. +- 4) Upon reception of the TIGAV-ACK response, the VTU-O shall expect receiving the first segment of a TIGAVRESP command. The VTU-O shall either acknowledge the last segment of the TIGAVRESP command by sending a TIGAVRESP-ACK response, or reject the TIGAVRESP command by sending a TIGAVRESP-Reject response with a corresponding reason code. After sending the TIGAVRESP-ACK response, at the time determined by the VCE, the VTU-O shall send the TIGAV-SYNCHRO pattern. After sending the TIGAVRESP-Reject response, the VTU-O shall exit the TIGAV procedure. + +NOTE 4 – The TIGAV-SYNCHRO pattern has to be sent simultaneously over all relevant lines of the vectored group. For this the VCE needs to receive the TIGAVRESP command from all lines in the vectored group prior to sending TIGAV-SYNCHRO pattern. This should be within the global TIGAV timeout. + +- 5) Upon reception of a TIGAV-Reject response, the VTU-O shall exit the TIGAV procedure. The VTU-O may immediately start a new TIGAV procedure by sending a new TIGAV command. +- 6) Upon reception of a TIGAVRESP-Reject response, the VTU-R shall send a TIGAVRESP command again. If rejection persists, the VTU-R shall exit the TIGAV procedure. +- 7) Starting from the first symbol following the TIGAV-SYNCHRO pattern, both the VTU-O and the VTU-R shall synchronously apply the relative gain compensation factor indicated in the TIGAV command and the bit loading indicated in the TIGAVRESP command. + +Timing of changes in framing parameters shall be as specified in clause C.4 of [ITU-T G.998.4]. + +- 8) The procedure times out if TIGAV-SYNCHRO is not received within 4 seconds after the VTU-R sends TIGAV ACK. Upon this timeout, the VTU-R shall exit the TIGAV procedure. + +![Timing diagram of TIGAV procedure showing message exchanges between VTU-O and VTU-R with timing constraints.](b3d488012fdceacab867cf24c5efef05_img.jpg) + +The diagram illustrates the timing sequence for the TIGAV procedure between a VTU-O (Vendor Terminal Unit - Operator) and a VTU-R (Vendor Terminal Unit - Remote). The sequence of messages is as follows: + +- The VTU-O sends the **First segment of TIGAV** and **Last segment of TIGAV** to the VTU-R. The time interval between these two segments is less than 100 ms (< 100 ms). +- The VTU-R responds with an **ACK** message. The time interval from the start of the TIGAV segments to the receipt of the ACK at the VTU-O is less than 300 ms (< 300 ms). +- The VTU-O then sends the **First segment of TIGAVRESP** and **Last segment of TIGAVRESP** to the VTU-R. The time interval between these two segments is less than 100 ms (< 100 ms). +- The VTU-R responds with another **ACK** message. The time interval from the start of the TIGAVRESP segments to the receipt of this ACK at the VTU-O is less than 4 seconds (< 4 s). +- Finally, the VTU-O sends a **TIGAV-SYNCHRO** message to the VTU-R. The time interval from the receipt of the second ACK at the VTU-O to the receipt of the TIGAV-SYNCHRO at the VTU-R is less than 4 seconds (< 4 s). + +At the bottom of the diagram, a horizontal dashed line separates the 'Old settings' from the 'New settings'. + +G.993.5(15)-Amd.2(17)\_FA.1 + +Timing diagram of TIGAV procedure showing message exchanges between VTU-O and VTU-R with timing constraints. + +**Figure A.1 – Timing diagram of TIGAV procedure** + +NOTE 5 – Figure A.1 does not show the case of rejecting the TIGAV command and does not show the case of rejecting the TIGAVRESP command. + +#### A.6.2.1 Definition of TIGAV-SYNCHRO pattern + +The TIGAV-SYNCHRO pattern is defined as consisting of one sync symbol with inverted flag tones (transmitted at the end of the superframe, at the sync symbol position, see Figure 10-2 of [ITU-T G.993.2]), followed by a pattern of 9 sync symbols with non-inverted flag tones (transmitted at the first 9 symbol positions in the next superframe). + +The sync symbol is defined in clause 10.2 of [ITU-T G.993.2]. + +#### A.6.2.2 Implementing the TIGAV gain modification by the VTU-R + +To implement the relative gain compensation factor ( $r_i$ ) indicated in the TIGAV, the following rules shall apply: + +- For subcarriers with $r_i \neq 0$ , the VTU-R shall multiply its current settings of the gain stage in the receiver, for any subcarrier $i$ with $g_i > 0$ , by the value ( $r_i$ ): + +$$new\_gainstage_i = current\_gainstage_i \times r_i$$ + +NOTE – This scaling is to help the VTU-R to keep its receiver gain adjusted after a precoder update. + +- For subcarriers with $r_i = 0$ , the VTU-R shall set its receiver gain to a vendor discretionary non-zero value. + +#### A.6.2.3 Relation TIGAV and subsequent autonomous SRA in downstream + +An autonomous SRA requested by the VTU-R, subsequent to a TIGAV command, shall have bit loading values $b_i$ that are less than or equal to the $b_i$ values requested in the last TIGAV message preceding this SRA. + +## A.7 Main body amendments related to MREFPSD + +### A.7.1 Definitions (replaces clauses 3.31 and 3.32 of [ITU-T G.993.2]) + +**3.31 MEDLEY reference PSD:** The MEDLEY reference PSDs in the downstream and upstream directions are denoted as MREFPSDds and MREFPSDus, respectively. The MREFPSDus is the PSD of signals transmitted by a VTU-R at every frequency (i.e., in both the passband and the stopbands) during the training phase and the channel analysis and exchange phase of initialization. The MREFPSDds is the power spectral density (PSD) of signals transmitted by a VTU-O at every frequency (i.e., in both the passband and the stopbands) during the training phase only. + +NOTE – In this Recommendation, including in this Annex, the MREFPSDds refers to the VTU-O TXPSD of the direct signal only, without pre-compensation signals. In [b-ITU-T G.9701], the MREFPSDds refers to the FTU-O TXPSD of the total signal at the U-interface, including pre-compensation signals. + +**3.32 MEDLEY reference PSD mask:** The MEDLEY reference PSD mask is the transmit PSD mask limited at every frequency (i.e., in both the passband and the stopbands) by the PSD ceiling and limited to $-80$ dBm/Hz at frequencies corresponding to the designated RFI bands. In the upstream direction, the MEDLEY reference PSD mask is further reduced in accordance with the upstream power back off (UPBO) requirements. The MEDLEY reference PSD masks in the downstream and upstream directions are denoted as MREFMASKds and MREFMASKus, respectively. + +### A.7.2 Nominal aggregate transmit power (NOMATP) (replaces clause 10.3.4.2.1 of [ITU-T G.993.2]) + +NOTE – Unless otherwise specified, references in this clause refer to [ITU-T G.993.2]. + +The nominal aggregate transmit power in upstream (NOMATPus) shall be calculated at both the VTU-R and the VTU-O side as defined in clause 10.3.4.2.1 of [ITU-T G.993.2]. + +At the VTU-R side, the nominal aggregate transmit power in downstream (NOMATPds) shall be calculated as defined in clause 10.3.4.2.1 of [ITU-T G.993.2]. The $g_i$ settings determined by the VTU-R shall be such that the value of this NOMATPds (as defined for the VTU-R) does not exceed, the CO-MIB parameter MAXNOMATPds. At the VTU-O side, the nominal aggregate transmit power in downstream (NOMATPds) is an estimate of the total amount of output power delivered by the transmit PMD function to the U-O2 reference point (defined in Figure 5-4 of [ITU-T G.993.2]) in dBm into a 100 Ohm termination impedance. + +The nominal aggregate transmit power in downstream (NOMATPds) shall be computed by VTU-O, in cooperation with the VCE, according to the following equation: + +$$NOMATPds = 10 \log_{10} \left( \sum_{i \in MEDLEYds} P\_Zi' \right)$$ + +where $P\_Zi'$ is the power of the total transmitted signal at the output of the precoder for subcarrier $i$ , referred to the U-O interface, in milliWatts assuming the network input impedance is 100 Ohms resistive (see Note 1). + +NOTE 1 – In actual deployments, the network/loop input impedance may deviate from 100 Ohms resistive. + +NOTE 2 – NOMATPds includes the direct signal as well as the precoder compensation signals. + +The VTU-O, in cooperation with the VCE, shall ensure that the value of NOMATPds does not exceed, the CO-MIB parameter MAXNOMATPds. + +NOTE 3 – The definition of NOMATPds is different at the VTU-R and VTU-O side. At the VTU-R side, the definition of NOMATPds is unchanged compared to [ITU-T G.993.2], and therefore the VTU-R $g_i$ calculation is unchanged. At the VTU-O side, the definition of NOMATPds is changed compared to [ITU-T G.993.2]. + +The total amount of output power delivered by the transmit PMD function to the U-O2 reference point in dBm into a 100 Ohm termination impedance shall not deviate from the NOMATPds by more than 1 dB. + +### A.7.3 Frequency-domain transmit spectrum shaping ( $tss_i$ ) (replaces clause 10.3.4.3 of [ITU-T G.993.2]) + +NOTE – Unless otherwise specified, references in this clause refer to [ITU-T G.993.2]. + +The $tss_i$ are intended for frequency-domain spectrum shaping, both upstream and downstream. The $tss_i$ values are vendor discretionary and shall be in the range between 0 and 1 (linear) in steps of $\frac{1}{1024}$ . The $tss_i$ values shall be set such that the highest $tss_i$ value across all subcarriers is 1. Smaller values of $tss_i$ provide attenuation, and the value $tss_i = 0$ corresponds to no power transmitted on the particular subcarrier. If no frequency-domain spectrum shaping is applied, the $tss_i$ values shall be equal to 1 for all subcarriers. + +The $tss_i$ values in dB ( $\log\_tss_i$ ) are defined as $20 \times \log_{10}(tss_i)$ and shall be converted to linear values of $tss_i$ using the equation: + +$$tss_i = \frac{\text{Round} \left( 1024 \times 10^{\frac{\log\_tss_i}{20}} \right)}{1024}$$ + +The values of $tss_i$ for the given direction of transmission shall be determined by the transmitting VTU, and shall be defined as a set of breakpoints $\{(i_1, \log\_tss_{i1}), \dots, (i_n, \log\_tss_{in})\}$ , where $i$ is the subcarrier index. This set shall be communicated to the receiving VTU during the channel discovery phase of the initialization using O-PRM and R-PRM messages, as described in clause 12.3.3.2. Both transmitting and receiving VTUs shall derive the $tss_i$ values for subcarriers between the breakpoints using linear interpolation of the defined $\log\_tss_i$ values over the linear scale of subcarrier indexes. The receiving VTU shall assign $tss_i$ values equal to $tss_{in}$ for $i > i_n$ , and equal to $tss_{i1}$ for $i < i_1$ . + +The obtained values of $tss_i$ are relevant only for subcarriers that are actually transmitted. The receiver shall ignore the $tss_i$ values that are either received or obtained by interpolation for the subcarriers that are not used for transmission ( $Z_i=0$ , see Table 10-4). + +The combined accuracy of the linear interpolation of $\log\_tss_i$ values and of the conversion to linear $tss_i$ values shall be less than one half LSB for the 10-bit representation format of the linear $tss_i$ values. No error shall be introduced when $\log\_tss_i$ equals 0 dB or is interpolated between $\log\_tss_i$ values that equal 0 dB. + +The transmitter of the VTU-O shall set the $tss_i$ values such that the PSD of the transmit signal as measured in the reference impedance at the U-O2 reference point, during the training phase, shall not deviate from the values of MREFPSDds, communicated in O-PRM, by more than 1 dB (parameter "MEDLEY reference PSD", see clause 12.3.3.2). + +The transmitter of the VTU-R shall set the $tss_i$ values such that, prior to the gain adjustment (i.e., assuming $g_i=1$ ), the PSD of the transmit signal as measured in the reference impedance at the + +U interface, from the start of the training phase and for the remainder of initialization, shall not deviate from the values of MREFPSDus, communicated in R-PRM, respectively, by more than 1 dB (parameter "MEDLEY reference PSD", see clause 12.3.3.2). + +Thus, $t_{ss_i}$ settings shall take into consideration any additional spectrum shaping caused by time-domain filters and analog filters included in the transmission path between the output of the modulator and U interface. + +### A.7.4 General (amends clause 6.1 of ITU-T G.993.5) + +... + +As a part of the channel matrix or separately, the VCE shall set the precoder such that the precoder output signals ( $Z'$ values shown in Figure 6-1) shall not lead at the U-O2 reference point to violation of the MREFMASK, even with highest valid $g_i$ values (i.e., $g_i = +2.5$ dB) for all lines in the vectored group. + +### A.7.5 PSD and PSD mask summary (amends clause 7.2.3 of [ITU-T G.993.2]) + +NOTE – Unless otherwise specified, references in this clause refer to [ITU-T G.993.2]. + +... + +**Table 7-5 – Summary: Determination and use of PSDs and PSD masks** + +| Parameter | When determined | When communicated between VTUs (Note) | When used | +|---------------------------------------------|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------| +| MEDLEY reference PSD mask (MREFMASK) | At the end of channel discovery phase; VTU-O determines MREFMASKds, VTU-R determines MREFMASKus | Not communicated | From the beginning of training phase and thereafter during initialization and showtime | +| MEDLEY reference PSD downstream (MREFPSDds) | At the end of channel discovery phase; VTU-O determines MREFPSDds | MREFPSDds is sent by VTU-O to VTU-R in O-PRM | During the training phase | +| MEDLEY reference PSD upstream (MREFPSDus) | At the end of channel discovery phase, VTU-R determines MREFPSDus | MREFPSDus is sent by VTU-R to VTU-O in R-PRM | During the training phase and channel analysis and exchange phase | +| Showtime PSD | At the end of the channel analysis and exchange phase | Determined by the PSD of the channel analysis and exchange phase and the gain values ( $g_i$ ) communicated during the channel analysis and exchange phase (O-PMD and R-PMD messages). Shall not exceed MREFMASK. | During showtime | + +NOTE – Only the minimum set of relevant parameters characterizing PSDs and PSD masks is communicated during initialization. The communication protocols and formats are described in clause 12. + +### A.7.6 Channel characteristics function per subcarrier group (CCF-ps) (amends clause 11.4.1.1.1 of [ITU-T G.993.2]) + +NOTE – Unless otherwise specified, references in this clause refer to [ITU-T G.993.2]. + +... + +The measurement of a channel characteristics function is the result of the cascade of three functions: + +- the transmitter filter characteristics function; +- the channel characteristics function; and +- the receiver filter characteristics function. + +NOTE 1 – The channel characteristics function corresponds to the $H_{\text{channel}}(f)$ function used in the definition of the far-end crosstalk (see clause 7.4.1 of [ITU-T G.996.1]). + +The objective is to provide means by which the channel characteristics can be accurately identified. Therefore, it is necessary for the receive PMD function to report an estimate of the channel characteristics. This task may prove to be a difficult one given the fact that the receive PMD function only observes the cascade of all three elements of the channel. The passband part of the reported $H(f)$ , which is most essential to debug possible issues with the physical loop, is not expected to significantly depend upon the receiver filter characteristics (not including receiver AGC). The receive PMD function shall therefore invert the gain (AGC) it has applied to the received signal and do a best effort attempt to remove the impact of the near-end receiver filter characteristics. The result is then a best estimate of how the receiver views the passband channel characteristics plus the transmitter filter characteristics. As the in-band portion of the spectrum is also expected not to significantly depend upon the transmitter filter characteristics, this result is considered a sufficient estimate of the channel characteristics for desired loop conditioning applications. + +Two formats are defined for the channel characteristics as follows: + +- $H_{\text{lin}}(f)$ : a format providing complex values on a linear scale; and +- $H_{\text{log}}(f)$ : a format providing magnitude values on a base 10 logarithmic scale. + +For $H_{\text{log}}(f)$ , the receive PMD function shall also use the value of the PSD at the U interface of the transmit PMD function (as conveyed in messages during initialization) to remove the impact of the far-end transmit filter characteristics. + +NOTE 2 – The $H_{\text{log}}$ includes the effect of the precompensation signals related to that line sent on the other lines of the vectored group which are in the L0 link state. + +For $H_{\text{lin}}(f)$ , if the channel characteristics are reported over the VTU-O OAM interface (see Figure 5-3), the VTU-O shall do a best effort attempt to remove the impact of the near-end transmit filter characteristics from the channel characteristics measured at the VTU-R. If the channel characteristics are reported over the VTU-R OAM interface, the VTU-R shall do a best effort attempt to remove the impact of the near-end transmit filter characteristics from the channel characteristics measured at the VTU-O. + +NOTE 3 – The $H_{\text{lin}}$ includes the effect of the precompensation signals related to that line sent on the other lines of the vectored group which are in the L0 link state. + +$H_{\text{lin}}(f)$ shall be sent to the far-end VME during the loop diagnostic mode and shall be sent on request to the near-end VME during the loop diagnostic mode. + +... + +### **A.7.7 PMD Test Parameter Read commands and responses (replaces clause 11.2.3.11 of [ITU-T G.993.2])** + +NOTE – Revision marks in this clause show the changes relative to clause 11.2.3.11 of [ITU-T G.993.2]. + +Unless otherwise specified, references in this clause refer to [ITU-T G.993.2]. + +The PMD Test Parameter Read commands shall be used to retrieve the values of the PMD test parameters that are specified in clause 11.4.1 and maintained by the far-end VTU. The PMD Test Parameter Read commands are shown in Table 11-26, and may be initiated by either VTU. The + +responses shall be as shown in Table 11-27. The first octet of all PMD Test Parameter Read commands and responses shall be the assigned value for the PMD Test Parameter Read command type, as shown in Table 11-5. The subsequent octets of the commands shall be as shown in Table 11-26. The subsequent octets of the responses shall be as shown in Table 11-27. The octets shall be sent using the format described in clause 11.2.3.1. + +**Table 11-26 – PMD test parameter read commands sent by the requesting VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|---------------------------------|-----------------|----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------| +| Single Read | 2 | 2 | 01 16 (Note 1) | Mandatory | +| Next Multiple Read | 2 | 2 | 03 16 (Note 1) | Mandatory | +| Multiple Read | 4 | 2 | 04 16 (Note 1) | Mandatory | +| | | 3 to 4 | 2 octets describing the subcarrier group index | | +| Block Read | 6 | 2 | 05 16 (Note 1) | Mandatory | +| | | 3 to 4 | 2 octets describing the start subcarrier group index | | +| | | 5 to 6 | 2 octets describing the stop subcarrier group index | | +| Vector Block Read | 7 | 2 | 06 16 (Note 1) | Optional | +| | | 3 | 1 octet describing the type of test parameter to read (Note 2)
01 16 : Channel transfer function Hlog( f ) per subcarrier group
03 16 : Quiet Line Noise PSD QLN( f ) per subcarrier group
04 16 : Signal to noise ratio SNR( f ) per subcarrier group. | | +| | | 4 to 5 | 2 octets describing the start subcarrier group index | | +| | | 6 to 7 | 2 octets describing the stop subcarrier group index | | +| Scalar Read | 3 | 2 | 07 16 (Note 1) | Optional | +| | | 3 | 1 octet describing the type of scalar test parameters to be read (Note 2)
21 16 to 28 16 : the parameter index to read according to the ID of Table 11-28. | | +| SATN for G.993.5 Annex A | 12 | 2 | 0816 (Note 1) | Mandatory | +| | | 3 to 12 | Five 2-octet values of TXpower_dBm D(m) for 5 potentially available downstream bands. | | + +NOTE 1 – All other values for octet number 2 are reserved by the ITU-T. +NOTE 2 – All other values for octet number 3 are reserved by the ITU-T. + +**Table 11-27 – PMD test parameter read responses sent by the responding VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-------------|-----------------|--------------|---------------------------|-----------| +| Single Read | 42 | 2 | 81 16 (Note 2) | Mandatory | + +**Table 11-27 – PMD test parameter read responses sent by the responding VTU** + +| Name | Length (octets) | Octet number | Content | Support | +|-------------------------------------|------------------------------|----------------|----------------------------------------------------------------------|------------------| +| ACK | (Note 1) | 3 to 42 | Octets for the test parameters arranged for the single read format | | +| Multiple Read ACK | 12 (Note 1) | 2 | 82 16 (Note 2) | Mandatory | +| | | 3 to 12 | Octets for the test parameters arranged for the multiple read format | | +| NACK | 2 | 2 | 80 16 (Note 2) | Mandatory | +| Block Read ACK | Parameter-dependent (Note 1) | 2 | 84 16 (Note 2) | Mandatory | +| | | 3 + | Octets for the test parameters arranged for the block read format | | +| Vector Block Read ACK | Parameter-dependent (Note 1) | 2 | 86 16 (Note 2) | Optional | +| | | 3 + | Octets for the test parameters arranged for the block read format | | +| Scalar Read ACK | Parameter-dependent (Note 1) | 2 | 87 16 (Note 2) | Optional | +| | | 3 + | Octets for the test parameters arranged for the scalar read format | | +| SATN for G.993.5 Annex A ACK | 12 (Note 1) | 2 | 8816 (Note 2) | Mandatory | +| | | 3 to 12 | Octets for SATN arranged for the scalar read format | | + +NOTE 1 – Message length equals 2 octets plus the length shown in Table 11-28. +NOTE 2 – All other values for octet number 2 are reserved by the ITU-T. + +**Table 11-28 – PMD test parameter ID values and length of responses** + +| Test parameter ID (Note 1) | Test parameter name | Length for Single Read (octets) | Length for Multiple Read (octets) | Length for Block Read or Vector Block Read (octets) | Length for Scalar Read (octets) | Support | +|----------------------------|-----------------------------------------------------------------|---------------------------------|-----------------------------------|-----------------------------------------------------------------------------------|---------------------------------|-----------| +| 01 16 | Channel transfer function Hlog( f ) per subcarrier group | N/A | 4 | 2 + (stop subcarrier group index – start subcarrier group index + 1) × 2 (Note 2) | N/A | Mandatory | +| 03 16 | Quiet line noise PSD QLN( f ) per subcarrier group | N/A | 3 | 2 + (stop subcarrier group index – start subcarrier group index + 1) (Note 2) | N/A | Mandatory | +| 04 16 | Signal-to-noise ratio SNR( f ) per subcarrier group | N/A | 3 | 2 + (stop subcarrier group index – start subcarrier group index + 1) (Note 2) | N/A | Mandatory | + +**Table 11-28 – PMD test parameter ID values and length of responses** + +| Test parameter ID (Note 1) | Test parameter name | Length for Single Read (octets) | Length for Multiple Read (octets) | Length for Block Read or Vector Block Read (octets) | Length for Scalar Read (octets) | Support | +|----------------------------|--------------------------------------------------------------------------------------|---------------------------------|-----------------------------------|-----------------------------------------------------|---------------------------------|-----------| +| 21 16 | Loop attenuation LATN | 2 × 5 | N/A | N/A | 2 × 5 | Mandatory | +| 22 16 | Signal attenuation SATN | 2 × 5 | N/A | N/A | 2 × 5 | Mandatory | +| 23 16 | Signal-to-noise ratio margin SNRM and SNRM-pb | 2 × 6 | N/A | N/A | 2 × 6 | Mandatory | +| 24 16 | Attainable net data rate ATTNDR (basic method) | 4 | N/A | N/A | 4 | Mandatory | +| 24 16 | Attainable net data rate ATTNDR (improved method) | 8 | N/A | N/A | 8 | Optional | +| 25 16 | Near-end actual aggregate transmit power ACTATP | 2 | N/A | N/A | 2 | Mandatory | +| 26 16 | Far-end actual aggregate transmit power ACTATP | 2 | N/A | N/A | 2 | Mandatory | +| 27 16 | Far-end actual impulse noise protection INP_act | N/A | N/A | N/A | 2 | Optional | +| 28 16 | Far-end actual signal-to-noise ratio margin for the robust overhead channel SNRM-ROC | N/A | N/A | N/A | 2 | Optional | + +NOTE 1 – All other Test parameter ID values are reserved by the ITU-T. + +NOTE 2 – Since the number of subcarriers, $G$ , in the subcarrier group (see clause 11.4.1) may be different for QLN, Hlog, and SNR, the values of QLN, Hlog and SNR communicated by Multiple Read, Block Read, or Vector Block Read for the same subcarrier group index may correspond to different subcarrier indices. The subcarrier index for each parameter equals $G \times \text{subcarrier group\_index}$ , where the value of $G$ is as defined in Table 11-42 of clause 11.4.1 (for showtime) and subcarrier group index = 0 to 511. + +Upon reception of a PMD Test Parameter Read command, the responding VTU shall send the corresponding response. If the format of the Test Parameter Read command is incorrect, the VTU shall respond with the negative acknowledge (NACK). Any function of either the requesting or the responding VTU shall not be affected. + +The Single Read command shall be used to retrieve all test parameters with ID values from 2116 to 2616 inclusive. In response to a Single Read command, the values for the test parameters (one value per parameter) shall be transferred in numerically increasing order of the parameter ID shown in Table 11-28. The format of the octets for each parameter shall be as specified in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The LATN, SATN and SNRM format shall include five 2-octet values intended for 5 potentially available frequency bands for each transmission direction. The 2-octet values shall be sent in the order shown in Table 11-29. The value 0016 shall be used to indicate the disabled bands. Octets indicated as reserved shall be set to ZERO in the transmitter and ignored by the receiver. The SNRM test parameter shall, in addition to all SNRM-pb values (clause 11.4.1.1.6.3), include the overall SNRM value (clause 11.4.1.1.6.2). The first 2-octet value is the overall SNRM, followed by the five 2-octet values of the SNRM-pb as specified in Table 11-29. For the ATTNDR, the use of either the basic or the improved method is configured during initialization (see clause 11.4.1.1.7). The ATTNDR test parameter is specified in Table 11-30. + +If operating according to Annex A of [ITU-T G.993.5], the VTU-R response to a scalar read command for SATN and to a single read command shall have SATN values equal to the special value 1023. The VTU-O shall ignore this value (i.e., the VME shall not communicate this value to the EIA for storing in the CO-MIB SATNds object). + +**Table 11-29 – Order for sending LATN, SATN and SNRM-pb parameters** + +| Octet number | Upstream direction | Downstream direction | +|--------------|--------------------|----------------------| +| 1 | US0 | DS1 | +| 2 | | | +| 3 | US1 | DS2 | +| 4 | | | +| 5 | US2 | DS3 | +| 6 | | | +| 7 | US3 | DS4 | +| 8 | | | +| 9 | US4 | Reserved | +| 10 | | | + +**Table 11-30 – ATTNDR test parameter** + +| Octet number | Basic method | Improved method | +|------------------------------------------------------------------|---------------|--------------------------------------| +| 1-4 | ATTNDR | ATTNDR | +| 5 | N/A | Reserved and set to 00 16 | +| 6 | N/A | ATTNDR_INP_act0 | +| 7 | N/A | Reserved and set to 00 16 | +| 8 | N/A | ATTNDR_delay_act0 | +| NOTE – The format of the fields is defined in clause 11.4.1.1.7. | | | + +A Scalar Read command shall be used to retrieve a single test parameter. Support of this read command is optional. The ID of the test parameter to retrieve shall be indicated in the third octet of the read command as specified in Table 11-26. In response to a Scalar Read command, the VTU shall send the value of the test parameter if this command and the test parameter are supported by the VTU; otherwise the VTU shall send a NACK. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The format of the LATN, SATN, SNRM and ATTNDR shall be identical to the format used in Single Read Command. The Far-end actual impulse noise protection (ID=2716) shall include two 1-octet values and be sent in the order shown in Table 11-31. The value FF16 shall be used to indicate the disabled bearers. + +**Table 11-31 – Order for sending far-end actual impulse noise protection parameters** + +| Octet number | Parameter | +|--------------|------------------------------| +| 1 | INP_act for bearer channel 0 | +| 2 | INP_act for bearer channel 1 | + +The "SATN for G.993.5 Annex A" command shall be used to retrieve SATN in case of operation according to Annex A of [ITU-T G.993.5]. It shall include five 2-octet values of TXpower\_dBm\_D(m) for 5 potentially available downstream bands. The format of the octets for each parameter shall be as specified for the actual aggregate transmit power (ACTATP) in clause 11.4.1.1.8. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The 2-octet values shall be sent in the order shown in Table 11-29. The value 0016 shall be used to indicate the disabled bands. Octets indicated as reserved shall be set to ZERO in the transmitter and ignored by the receiver. + +In response to a "SATN for G.993.5 Annex A" command, the VTU shall send the value of SATN. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The format of the SATN shall be identical to the format used in Scalar Read Command. The VTU-O shall convey this value for storing in the CO-MIB SATNds object. + +In case the VTU-R detects a TIGAV or other OLR procedure after the SATN command and before the response, the VTU-R shall respond with SATN values equal to the special value 1023. The VTU-O shall convey this value for storing in the CO-MIB SATNds object and further reinitiate the SATN command. The VME-O shall communicate this value to the EIA for storing in the CO-MIB SATNds object. The VME-O shall reinitiate the SATN command. Timing for this reinitiation is vendor discretionary. + +Multiple Read and Next Multiple Read commands shall be used to retrieve test parameters of one subcarrier group. In response to a Multiple Read or Next Multiple Read command, the VTU shall send information for test parameters with ID 0116, 0316, and 0416 associated with the indicated subcarrier group. The Multiple Read command contains the index of the requested subcarrier group + +(see Table 11-26). If a Next Multiple Read command is to be sent, it shall only be sent after a Multiple Read command. In response to each subsequent Next Multiple Read command, the subcarrier group index shall be incremented by one. If the subcarrier group index exceeds 511 (see clause 11.4.1), the response shall be a NACK. The values of the PMD parameters per subcarrier group shall be inserted into the message in numerical order of the parameter ID shown in Table 11-28. The format of the octets for each parameter shall be as described in clause 11.4.1. Values that are formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. + +A Block Read command shall be used to retrieve test parameters over a range of subcarrier groups. In response to a Block Read command, the VTU shall send information for test parameters with ID 0116, 0316, and 0416 associated with the specified block of subcarrier groups. For test parameters specified per subcarrier group, all values for subcarrier groups with indices from #start to #stop are transferred in a single response. If the subcarrier group index exceeds 511, the response shall be a NACK. The values of the PMD parameters per subcarrier group shall be inserted into the message in increasing order of the parameter ID shown in Table 11-28. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. The number of octets in a Block Read command shall not exceed the maximum length P of the eoc message specified in clause 11.2.3.1. + +A Vector Block Read command shall be used to retrieve a single test parameter over a range of subcarrier groups. Support of this read command is optional. The ID of the test parameter to retrieve shall be indicated in the third octet of the read command as specified in Table 11-26. In response to a Vector Block Read command, the VTU shall send information for the test parameter associated with the specified block of subcarrier groups if this command is supported by the VTU; otherwise the VTU shall send a NACK. All values for subcarrier groups with indices from #start to #stop are transferred in a single response. If the subcarrier group index exceeds 511, the response shall be a NACK. The format of the octets for each parameter value shall be as described in clause 11.4.1. Values formatted as multiple octets shall be mapped to the response in order of most significant to least significant octet. + +When transferring values of the channel transfer function $H\log(f)$ , the quiet line noise $QLN(f)$ , and the signal-to-noise ratio $SNR(f)$ , the measurement time shall be included in the response for each test parameter. The ACK (see Table 11-27) is followed by the $H\log(f)$ measurement time and the value $m$ (see clause 11.4.1.1.1), followed by the $QLN(f)$ measurement time and value $n$ (see clause 11.4.1.1.2), followed by the $SNR(f)$ measurement time and value $SNR$ (see clause 11.4.1.1.3), respectively. The measurement time shall be included only once in a response to a Block Read or Vector Block Read command, and shall be included for each test parameter in each response to a Multiple Read or Next Multiple Read command. + +The values of some test parameters are represented using fewer bits than contained in the corresponding field defined for the response in Table 11-28. In the case that the field has more than one octet, the bits shall be mapped to the LSBs of the multi-octet field in the response. Unused MSBs in the multi-octet field shall be set to ZERO for unsigned quantities and to the value of the sign bit for signed quantities. + +### **A.7.8 Signal attenuation per band (SATN-pb) (replaces clause 11.4.1.1.5 of [ITU-T G.993.2])** + +The signal attenuation in the $m^{\text{th}}$ downstream band is denoted as $SATN\_D(m)$ , and the signal attenuation in the $m^{\text{th}}$ upstream band is denoted as $SATN\_U(m)$ . + +When operating in ITU-T G.993.5 Annex A, the signal attenuation of the $m^{\text{th}}$ upstream band, $SATN\_U(m)$ shall be calculated as specified in the main body of clause 11.4.1.1.5 of [ITU-T G.993.5]. + +When operating in accordance with Annex A of [ITU-T G.993.5], the signal attenuation of the $m^{\text{th}}$ downstream band, $\text{SATN\_D}(m)$ , is defined as the difference in dB between the power received at the near end and that transmitted from the far end in the $m^{\text{th}}$ downstream band. + +Mathematically, this corresponds to: + +$$\text{SATN\_D}(m) = \text{TXpower\_dBm\_D}(m) - \text{RXpower\_dBm\_D}(m)$$ + +During initialization and loop diagnostic mode, the received signal power in dBm, $\text{RXpower\_dBm\_D}(m)$ , shall be computed as the received subcarrier power, summed over those subcarriers of this band that are in the MEDLEYds set. The VTU-R shall assume that during transmission of O-P-MEDLEY, the transmit PSD for subcarriers in the MEDLEYds set is at the MREFPSDds level. Therefore, the received signal power shall be fine-tuned with the $g_i$ values for each subcarrier in the MEDLEYds set to estimate the signal power that will be received during showtime. + +Mathematically, this corresponds to: + +$$\text{RXpower\_dBm\_D}(m) = 10 \times \log_{10} \left( \sum_{i \in (\text{MEDLEYds} \cap \text{DS}(m))} (\text{Received\_subcarrier\_power\_mW}(i) \times g_i^2) \right)$$ + +During showtime, the received signal power in dBm, $\text{RXpower\_dBm\_D}(m)$ , shall be computed as the received subcarrier power in showtime, summed over those subcarriers of this band that are in the MEDLEYds set. + +Mathematically, this corresponds to: + +$$\text{RXpower\_dBm\_D}(m) = 10 \times \log_{10} \left( \sum_{i \in (\text{MEDLEYds} \cap \text{DS}(m))} (\text{Received\_subcarrier\_power\_mW}(i)) \right)$$ + +In both equations, $\text{MEDLEYds} \cap \text{DS}(m)$ denotes all subcarriers of the MEDLEYds set that fall into the $m^{\text{th}}$ downstream band, $\text{Received\_subcarrier\_power\_mW}$ is the received power on subcarrier $i$ expressed in milli-Watts, and $g_i$ is the gain (linear scale) for subcarrier $i$ . + +For the SATN value determined during initialization, the received signal power for each subcarrier $i$ in the MEDLEYds set shall be fine-tuned with the $g_i$ value conveyed in the O-PMD (for the upstream direction) and R-PMD (for the downstream direction) messages to estimate the signal power that will be received during showtime. During loop diagnostic mode, the fine tuning shall be restricted to using $g_i$ values 0 (for subcarriers to which no bits can be allocated) and 1 (for subcarriers to which at least one bit can be allocated). For the SATN value determined during Showtime, the received signal subcarrier power shall be taken as measured. + +For the SATN value determined during initialization and loop diagnostic mode, $\text{TXpower\_dBm\_D}(m)$ shall be computed by the VTU-R as the aggregate transmit power, summed over the subcarriers of this band that are in the MEDLEYds set. The VTU-R shall assume that during transmission of O-P-MEDLEY, the transmit PSD for subcarriers in the MEDLEYds set is at the MREFPSDds level. Therefore, the transmitted signal power shall be fine-tuned with the $g_i$ values for each subcarrier in the MEDLEYds set to estimate the signal power that will be transmitted during showtime. + +Mathematically, this corresponds to: + +$$\text{TXpower\_dBm\_D}(m) = 10 \times \log_{10} \Delta f + 10 \times \log_{10} \left( \sum_{i \in (\text{MEDLEYds} \cap \text{DS}(m))} \left( 10^{\frac{\text{MREFPSD}[i]}{10}} \times g_i^2 \right) \right)$$ + +where $MEDLEYds \cap DS(m)$ denotes all subcarriers of the MEDLEYds set that fall into the $m^{\text{th}}$ downstream band, $MREFPSD[i]$ is the value of MREFPSDds for subcarrier $i$ in dBm/Hz as conveyed by the O-PRM message, $g_i$ is the gain (linear scale) for subcarrier $i$ , and $\Delta f$ is the subcarrier spacing in Hz. + +The VTU-O, in cooperation with the VCE, shall update the downstream SATN value reported by the VTU-R during initialization using the correct TXpower\_dBm\_D(m) values. These shall be computed by the VTU-O, in cooperation with the VCE, as an estimate of the aggregate transmit power, summed over the subcarriers of this band that are in the MEDLEYds set, fine-tuned with the $g_i$ values for each subcarrier in the MEDLEYds set to estimate the signal power that will be transmitted during showtime. + +Mathematically, this corresponds to: + +$$TXpower\_dBm\_D(m) = 10 \log_{10} \left( \sum_{i \in (MEDLEYds \cap DS(m))} Pdirect\_Zi' \times g_i^2 \right)$$ + +where $MEDLEYds \cap DS(m)$ denotes all subcarriers of the MEDLEYds set that fall into the $m^{\text{th}}$ downstream band, and $Pdirect\_Zi'$ is the power of the direct signal at the output of the precoder for subcarrier $i$ , during O-P-MEDLEY, referred to the U-O interface, in milliWatts assuming the network input impedance is 100 Ohms resistive. + +NOTE 1 – In actual deployments, the network/loop input impedance may deviate from 100 Ohms resistive. + +NOTE 2 – In implementations using a precoder matrix $P_i$ for subcarrier $i$ , the $Pdirect\_Zi'$ may be computed using the diagonal coefficient of matrix $P_i$ , "diag( $P_i$ )", using the following equation: + +$$Pdirect\_Zi' = |diag(P_i)|^2 \times P_{Zi} = \Delta f \times 10^{\frac{MREFPSD(i)}{10}} \times (|diag(P_i)|)^2.$$ + +For the downstream SATN value determined during initialization, the transmit signal power for each subcarrier $i$ in the MEDLEYds set shall be fine-tuned with the $g_i$ value conveyed in the R-PMD (for the downstream direction) messages to estimate the transmit signal power during showtime. During loop diagnostic mode, the fine tuning shall be restricted to using $g_i$ values 0 (for subcarriers to which no bits can be allocated) and 1 (for subcarriers to which at least one bit can be allocated). + +For the downstream SATN value determined during showtime, the VTU-R shall use the TXpower\_dBm\_D(m) values as communicated by the VTU-O in the SATN test parameter request command. These shall be computed by the VTU-O, in cooperation with the VCE, as an estimate of the aggregate transmit power, summed over the subcarriers of this band that are in the MEDLEYds set. In showtime this power already incorporates the effect of the $g_i$ values. + +Mathematically, this corresponds to: + +$$TXpower\_dBm\_D(m) = 10 \log_{10} \left( \sum_{i \in (MEDLEYds \cap DS(m))} Pdirect\_Zi' \right)$$ + +where $MEDLEYds \cap DS(m)$ denotes all subcarriers of the MEDLEYds set that fall into the $m^{\text{th}}$ downstream band, and $Pdirect\_Zi'$ is the power of the direct signal at the output of the precoder for subcarrier $i$ , during showtime, referred to the U-O interface, in milliWatts assuming the network input impedance is 100 Ohms resistive. + +NOTE 3 – In actual deployments, the network/loop input impedance may deviate from 100 Ohms resistive. + +NOTE 4 – In implementations using a precoder matrix $P_i$ for subcarrier $i$ , the $Pdirect\_Zi'$ may be computed using the diagonal coefficient of matrix $P_i$ , "diag( $P_i$ )", using the following equation: + +$$Pdirect\_Zi' = |diag(P_i)|^2 \times P_{Zi} = \Delta f \times 10^{\frac{MREFPSD(i)}{10}} \times (|diag(P_i)| \times g_i)^2.$$ + +The signal attenuation shall be measured by the receive PMD function during loop diagnostic mode and initialization (i.e., estimate the signal attenuation at the start of showtime). The measurement shall be updated on request from the far-end during showtime. The signal attenuation shall be sent to the far-end on request during showtime. + +The signal attenuation per downstream band, $SATN\_D(m)$ , shall be represented as a 10-bit unsigned integer $satn$ , with the value of $SATN\_D(m)$ defined as $SATN\_D(m) = satn/10$ dB. This data format supports an $SATN\_D(m)$ granularity of 0.1 dB and an $SATN\_D(m)$ dynamic range of 102.2 dB (0 to 102.2 dB). + +An $SATN\_D(m)$ value indicated as $satn = 1023$ is a special value. It indicates that the signal attenuation is out of range to be represented or "undetermined". + +### A.7.9 Status parameter GAINSpds + +The status parameter $GAINSpds$ is defined as: + +$$GAINSpds_i = g_i \times 10^{\frac{(TXPSDdirect_{Zi'} - MREFPSDds(i))}{20}}$$ + +where: + +$TXPSDdirect\_Zi'$ is the PSD of the direct signal at the output of the precoder for subcarrier $i$ , referred to the U-O interface, in dBm/Hz assuming the network input impedance is 100 Ohms resistive; + +$MREFPSDds$ is the $MREFPSDds$ value as communicated in O-PRM in dBm/Hz. + +The $GAINSpds_i$ shall be updated by the VTU-O, in cooperation with the VCE, upon OLR that change the $g_i$ value, and upon TIGAV that change the $TXPSDdirect_{Zi'}$ value. + +NOTE 1 – The $GAINSpds$ is therefore only updated during the L0 link state. + +The valid values for $GAINSpds$ are from 0 to approximately 1.33 (i.e., maximum valid value of $g_i$ ). + +The $GAINSpds$ shall be represented as a 16-bit unsigned integer expressing the value of $GAINSpds$ in multiples of 1/512, with valid values from 0 to 682. All other values are reserved by ITU-T. + +NOTE 2 – If the VTU-O does not operate according to this annex, the $GAINSpds_i$ are the actual $g_i$ values. + +NOTE 3 – In implementations using a precoder matrix $P_i$ for subcarrier $i$ , the $GAINSpds$ may be computed using the diagonal coefficient of matrix $P_i$ , " $diag(P_i)$ ", using the following equation (see Figure 6-1): + +$$GAINSpds_i = g_i \times diag(P_i)$$ + +## A.8 Management + +This clause defines the CO-MIB configuration, status, and inventory parameters specific to Annex A operation. These parameters shall be supported if the VTU-O supports Annex A. + +### A.8.1 Configuration parameters + +#### A.8.1.1 STRONGFEXT mode (STRONGFEXT\_MODE) + +The configuration parameter STRONGFEXT\_MODE (see clause 7.3.1.17.1 of [ITU-T G.997.1]) is a configuration parameter used to control activation of ITU-T G.993.5 Annex A during initialization. + +This parameter has 4 valid values: + +0: DISABLED: ITU-T G.993.5 Annex A not allowed. The "Support of strong FEXT mitigation" Npar(3) bit in the ITU-T G.994.1 CL message shall be set to ZERO. + +1: PREFERRED: ITU-T G.993.5 Annex A is preferred by the operator. The "Support of strong FEXT mitigation" Npar(3) bit in the ITU-T G.994.1 CL message shall indicate whether the VTU-O supports this annex. + +2: FORCED: Force the use of the ITU-T G.993.5 Annex A. The "Support of strong FEXT mitigation" Npar(3) bit in the ITU-T G.994.1 CL message shall indicate whether the VTU-O + +supports this annex. If the "Support of strong FEXT mitigation" Npar(3) bit is not set to ONE in the ITU-T G.994.1 MS message or the "ITU-T G.993.5" Spar(2) bit is not set to ONE in the ITU-T G.994.1 MS message, then the "ITU-T G.993.2" Spar(1) bit shall be set to ZERO in the MS. + +###### 3: FORCED\_ABOVE\_17MHZ: + +- If the ITU-T G.994.1 MS message has the "ITU-T G.993.2" Spar(1) bit set to ONE and the "ITU-T G.993.5" Spar(2) bit set to ONE and the "Support of strong FEXT mitigation" Npar(3) bit set to ZERO, then the ITU-T G.994.1 MS message shall either + - select operation according to a profile other than 30a and 35b, or, + - select operation according to profile 35b, with a downstream and upstream SUPPORTEDCARRIERS set in O-SIGNATURE limited to subcarrier index 4095. +- If the ITU-T G.994.1 MS message has the "ITU-T G.993.2" Spar(1) bit is set to ONE and the "ITU-T G.993.5" Spar(2) bit set to ZERO, then the ITU-T G.994.1 MS message shall select operation according to any profile, with a downstream and upstream SUPPORTEDCARRIERS set in O-SIGNATURE limited to a vendor discretionary subcarrier index smaller than or equal to 4095. + +NOTE – The vendor discretionary highest subcarrier index should be chosen such that crosstalk generated to the other lines in the vectored group is sufficiently low, e.g., subcarrier 511 (which may correspond to ITU-T G.992.5 operation). + +If the STRONGFEXT\_MODE is set to PREFERRED, FORCED or FORCED\_ABOVE\_17MHz, then + +- the RA-MODEds shall be set to Mode 3 (DYNAMIC) or 4 (DYNAMIC with SOS); +- the RTX\_MODE\_ds shall be set to RTX\_FORCED, RTX\_PREFERRED or RTX\_TESTMODE. + +NOTE – This annex is only applicable if the VTU is operating according to Annex Q of [ITU-T G.993.2], which requires mandatory support of SRA and downstream retransmission. This annex assumes that SRA and downstream retransmission are enabled in the CO-MIB. + +If the STRONGFEXT\_MODE is set to FORCED or to FORCED\_ABOVE\_17MHz for one line in vectored group, it shall be set to the same mode for all lines in the vectored group (i.e., all or none). + +### A.8.2 Status parameters + +#### A.8.2.1 Actual STRONGFEXT mode (STRONGFEXT\_MODE\_ACTUAL) + +The STRONGFEXT\_MODE\_ACTUAL (see clause 7.5.1.45.1 of [ITU-T G.997.1]) status parameter reports for the line whether or not operation in accordance with Annex A of [ITU-T G.993.5] is selected in the ITU-T G.994.1 MS message (regardless whether this selection is autonomous by the VTUs or forced through the CO-MIB). + +The valid values are: + +- NOT-SELECTED: ITU-T G.993.5 Annex A operation *is not* selected. +- SELECTED: ITU-T G.993.5 Annex A operation *is* selected. + +### A.8.3 Inventory parameters + +#### A.8.3.1 STRONGFEXT mode support (STRONGFEXT\_MODE\_SUPPORT\_O/R) + +The STRONGFEXT\_MODE\_SUPPORT\_O (see clause 7.4.15.1 of [ITU-T G.997.1]) and STRONGFEXT\_MODE\_SUPPORT\_R (see clause 7.4.15.2 of [ITU-T G.997.1]) inventory parameters report, for the VTU-O and the VTU-R respectively, whether ITU-T G.993.5 Annex A operation is not supported (set to 0) or supported (set to 1). + +# Annex B + +## Vectored long reach VDSL2 + +(This annex forms an integral part of this Recommendation.) + +## B.1 Introduction + +This annex defines the long reach mode for vectored VDSL2 (VDSL2-LR). + +The VDSL2-LR mode is an optional functionality for both the VTU-O and VTU-R. This mode provides different behaviours for short loop, medium loop and long loop operation on different pairs in the same vectored group. The selection of short, medium, or long loop operation is autonomous, taking account of loop loss; unless the selection is overridden by network management. + +The behaviours include that: + +- 1) A deployment may host both VDSL2 and VDSL2-LR lines. The VDSL2-LR lines and the VDSL2 lines may be in the same vectored group. +- 2) If both VTU-O and VTU-R support VDSL2-LR mode, then operation according to this annex is selected during the ITU-T G.994.1 Handshake phase for both VTU-O and VTU-R. +- 3) Both VDSL2 lines and VDSL2-LR lines are configured to use a particular VDSL2 profile (e.g., 8a/b or 17a), depending on the desired service on VDSL2 lines. Both VDSL2 and VDSL2-LR lines start initialization according to the ITU-T G.993.5 procedure and the selected profile. +- 4) No overlapped spectrum is allowed in US0 – the frequency band from 25 to 138/276 kHz is used for US0 only and a regular VDSL2 bandplan is used above 138/276 kHz. +- 5) In VDSL2-LR mode, for the long loop operation, the spectrum is limited to US0 and DS1 up to subcarrier 511 (2.208 MHz). +- 6) Only the mandatory cyclic extension is supported in VDSL2-LR mode. +- 7) Unless explicitly stated otherwise in this annex, the VDSL2-LR mode supports all functionalities applicable to the main body of this Recommendation (e.g., DPBO). +- 8) Upstream crosstalk cancellation is not supported on lines where VDSL2-LR long loop operation is selected (since only the US0 band is used). + +## B.2 Overview of the initialization procedure + +The VDSL2-LR initialization procedure includes two parts: + +- 1) Regular ITU-T G.993.5 procedure (including ITU-T G.993.5 channel estimation) with minor modifications, and +- 2) Additional stages: + - PROBING: During this stage, the VTU-R determines the length of the line and indicates to the VTU-O whether to continue the VDSL2-LR initialization in short-medium loop operation or in long loop operation. Following the indication from the VTU-R, both the VTU-O and the VTU-R continue the initialization of the line either in short-medium loop operation or in long loop operation; + - TRAINING: This stage is present if the VTU-R selected to continue the initialization of the line in long loop operation. During this stage, the VTU-O and VTU-R train the line for long loop operation. + +The framework of the initialization procedure is presented in Figure B.1. It illustrates VDSL2-LR initialization (compared to regular ITU-T G.993.5 initialization), using the following notations for the exchanged signals: + +- G.993.5 signals – used if the line is a regular ITU-T G.993.5 line, i.e., not operating according to this annex (a regular ITU-T G.993.5 line); +- LR signals, short-medium – used if the line is selected during the PROBING stage to continue the VDSL2-LR initialization in short-medium loop operation (to become a short or medium VDSL2-LR line); +- LR signals, long – used if the line is selected during the PROBING stage to continue the VDSL2-LR initialization in long loop operation (for a long VDSL2-LR line). + +![](0f007a07756791edf7be50672cb010a4_img.jpg) + +| | Messages | LR signals, long | LR signals, short-medium | ITU-T G.993.5 signals | | ITU-T G.993.5 signals | LR signals, short-medium | LR signals, long | Messages | +|----------------------------------------------|----------------|--------------------------|--------------------------|-----------------------|--------------------------------------|-------------------------|--------------------------|-----------------------------------------|----------------| +| Regular part of ITU-T G.993.5 initialization | ITU-T G.994.1 | ITU-T G.994.1 handshake | | | | ITU-T G.994.1 handshake | | | ITU-T G.994.1 | +| | | O-P-QUIET 1 | | | | | | | | +| | | O-P-VECTOR 0 | | | | | | R-P-QUIET 1 | | +| Additional part performed in VDSL2-LR lines | O-P-MSG-PCB-LR | O-P-PROBING-LR | | | VTU-R obtained loop timing | | | R-P-PROBING-LR | R-P-MSG-PCB-LR | +| | | O-P-QUIET 1-LR | | | Decision short vs long | | | R-P-QUIET 1-LR | | +| | | O-P-VECTOR 1-LR | | O-P-VECTOR 1 | | R-P-QUIET 1 | | R-P-QUIET 2-LR | | +| | | O-P-TRAINING-LR | | O-P-VECTOR 1 | Regular ITU-T G.993.5 CD phase | | | R-P-TRAINING-LR | | +| Regular part of ITU-T G.993.5 initialization | O-IDLE | | | | | | | | | +| | O-SIGNATURE | O-P-CHANNEL DISCOVERY V1 | | | O-SIGNATURE received | | | R-P-QUIET 1 | | +| | | O-P-SYNCHRO V1 | | | | | | R-P-CHANNEL DISCOVERY 1 with SOC R-IDLE | | +| | O-IDLE | O-P-CHANNEL DISCOVERY 1 | | | Start of bi-directional transmission | | | | | +| | | O-P-SYNCHRO V1 | | | R-MSG 1 is received | | | R-P-CHANNEL DISCOVERY 1 | R-IDLE | +| | | | | | End of CD early stages | | | | R-MSG1 | +| | | O-P-PILOT 1 | O-P-QUIET 2 | | | | R-P-SYNCHRO 1 | | | +| | | | | | | | R-P-LINEPROBE | | | +| | .... | | .... | | | | .... | | | + +G.993.5(15)-Amd.2(17)\_FB.1 + +**Figure B.1 – Overview of the VDSL2-LR initialization (compared to regular ITU-T G.993.5 initialization)** + +## B.3 ITU-T G.994.1 Handshake phase + +During the ITU-T G.994.1 Handshake phase, it is determined whether the line is selected to be a VDSL2-LR line or selected to be a regular ITU-T G.993.5 line. The PROBING PSD (see clause B.6) in case the line is selected to be a VDSL2-LR line, is also indicated (via NOMPSD and *log\_tssi* values). The defined Spar(2) codepoints belongs to the ITU-T G.993.2 code-tree and defined in Table 11.68.0.1/G.994.1 (Standard information field – ITU-T G.993.2 SPar(2) coding – Octet 2). The use of these codepoints in the ITU-T G.994.1 CL, CLR and MS messages is defined in Tables B.1 to B.8. + +**Table B.1 – VTU-O CL message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|----------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR | Shall be set to ZERO if:
  • the VTU-O does not support VDSL2 Long Reach (VDSL2-LR) mode according to this annex, or,
  • none of short, medium or long loop operation type is allowed in the CO-MIB (see clause B.10.1.1), and
may be set to ONE otherwise. | +| Spectrum bounds downstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. If set to ONE, signifies that the VTU-O includes the spectrum bounds downstream defined in corresponding NPar(3). | +| Spectrum shaping downstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. If set to ONE, signifies that the VTU-O includes the spectrum shaping downstream defined in corresponding NPar(3). | +| Spectrum bounds upstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. If set to ONE, signifies that the VTU-O includes the spectrum bounds upstream defined in corresponding NPar(3). | +| Spectrum shaping upstream | Always set to ZERO. | +| Transmit signal images above the Nyquist frequency | Always set to ZERO. | +| Offset IDFT sample #0 downstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. | +| Offset IDFT sample #0 upstream | Always set to ZERO. | + +**Table B.2 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of NPar(3) bits | +|----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR | If the SPar(2) bit is set to ONE:
Bit 1: Short loop operation type: Shall be set to ONE if and only if VDSL2-LR short loop operation is allowed in the CO-MIB (see clause B.10.1.1).
Bit 2: Medium loop operation type: Shall be set to ONE if and only if VDSL2-LR medium loop operation is allowed in the CO-MIB (see clause B.10.1.1).
Bit 3: Long loop operation type: Shall be set to ONE if and only if VDSL2-LR long loop operation is allowed in the CO-MIB (see clause B.10.1.1).
Bit 4: Always set to ONE. | +| Spectrum bounds downstream | A parameter block indicating the nominal transmit PSD level. The parameter block length shall be 2 octets.
The nominal transmit PSD level ( NOMPSDds ) shall be represented as a 9-bit 2's-complement signed value in 0.1 dB steps, –25.6 to +25.5 dB, relative to the value of –40 dBm/Hz, and shall be coded in bits 3 down to 1 in octet 1, bits 6 down to 1 in octet 2. | + +**Table B.2 – VTU-O CL message NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of NPar(3) bits | +|----------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Spectrum shaping downstream |

A parameter block of pairs of a subcarrier index and the spectrum shaping \log\_tss_i value at that subcarrier. Pairs shall be transmitted in ascending subcarrier index order. Each pair shall be represented as 4 octets. The parameter block length shall be a multiple of 4 octets. The maximum number of breakpoints equals 32.

Codepoints shall be structured as:

The subcarrier index shall be a 9-bit unsigned value, indicating subcarrier index 1 to 2 \times NSCds - 1, coded in bits 3 down to 1 in octet 1, bits 6 down to 1 in octet 2;

The indication whether the subcarrier is included in the SUPPORTEDCARRIERS set (indication set to 1) or not included in the SUPPORTEDCARRIERSset (indication set to 0). This indication is coded in bit 6 of octet 3;

The spectrum shaping \log\_tss_i values shall be represented in logarithmic scale as a 7-bit unsigned value in -0.5 dB steps, ranging from 0 dB (value 0) to -62.5 dB (value 125), coded in bit 1 of octet 3 and bits 6 down to 1 in octet 4. Value 127 is a special value, indicating the subcarrier is not transmitted (i.e., tss_i = 0 in linear scale). Value 126 is a special value indicating that the \log\_tss_i value on this subcarrier shall be interpolated according to clause 8.13.2.4 of [ITU-T G.992.3]. At least one pair (of a subcarrier index and the spectrum shaping \log\_tss_i value at that subcarrier) indicated as included in the SUPPORTEDCARRIERS set, shall have the \log\_tss_i value set to 0 dB.

| +| Spectrum bounds upstream | Parameter block with same definition and structure as spectrum bounds downstream, with $NOMPSD=NOMPSDus$ . | +| Offset IDFT sample #0 downstream | Indicate the offset between the IDFT sample #0 of O-P-SEGUE 1-LR and O-P-CHANNEL DISCOVERY-V1 in samples at 4.416MHz. The value is coded as a 7-bits unsigned integer. | + +**Table B.3 – VTU-R CLR message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|-----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR | Shall be set to ONE if and only if the VTU-R supports VDSL2 Long Reach (VDSL2-LR) mode according to this annex. | +| Spectrum bounds downstream | Always set to ZERO. | +| Spectrum shaping downstream | Always set to ZERO. | +| Spectrum bounds upstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. If set to ONE, signifies that the VTU-R includes the spectrum bounds upstream defined in corresponding NPar(3). | +| Spectrum shaping upstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. If set to ONE, signifies that the VTU-R includes the spectrum shaping upstream defined in corresponding NPar(3). | + +**Table B.3 – VTU-R CLR message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|----------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmit signal images above the Nyquist frequency | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. If set to ONE, signifies that the VTU-R includes the transmit signal images above the Nyquist frequency defined in corresponding NPar(3). | +| Offset IDFT sample #0 downstream | Always set to ZERO. | +| Offset IDFT sample #0 upstream | Shall be set to ONE if and only if the "Support of VDSL2-LR" bit is set to ONE. | + +**Table B.4 – VTU-R CLR message NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of NPar(3) bits | +|----------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR |

Bit 1: Always set to ONE.

Bit 2: Always set to ONE.

Bit 3: Always set to ONE.

Bit 4: FMT-O-P-TREF2: If set to ONE, indicates that the VTU-R requests the VTU-O to transmit O-P-TREF symbols during O-P-ECT-LR. If set to ZERO, indicates that the VTU-R requests the VTU-O to transmit O-P-QUIET symbols during O-P-ECT-LR.

| +| Spectrum bounds upstream | Parameter block with same definition and structure as spectrum bounds upstream parameter block in CL message. | +| Spectrum shaping upstream | Parameter block with same definition and structure as spectrum shaping downstream parameter block in CL message, with $NSC=NSC_{us}$ and maximum number of breakpoints equals 16. | +| Transmit signal images above the Nyquist frequency |

A parameter block indicating the type of the transmit signal images above the Nyquist frequency. The parameter block shall consist of a single octet. Codepoints shall be structured as bits 6 to 3 indicating the N value (for a 2N point IDFT, see clause 10.4.3 of [ITU-T G.993.2]) and bits 2 and 1 indicating the definition of the transmit signal images above the Nyquist frequency (see clause 10.4.3 of [ITU-T G.993.2]). The coding shall be as follows:

  • • (b_6b_5b_4b_3) = n, with 1 \leq n \leq 15 indicates that N = 2^n.
  • • (b_2b_1 = 01): Complex conjugate of the base-band signal.
  • • (b_2b_1 = 10): Zero filled.
  • • (b_2b_1 = 00): Other (none of the above).
  • • (b_2b_1 = 11): Reserved.
| +| Offset IDFT sample #0 upstream | Indicate the offset between the IDFT sample #0 of R-P-SEGUE 1-LR and R-P-CHANNEL DISCOVERY 1 in samples at 276kHz. The value is coded as a 3-bits unsigned integer value. | + +**Table B.5 – VTU-O MS message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|---------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that both the VTU-O and the VTU-R shall continue initialization for VDSL2-LR mode as defined in this Annex. If set to | + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|----------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | ZERO, indicates that both the VTU-O and VTU-R shall continue initialization as defined in clause 10.
If this bit is set to ONE, then the CE length SPar(2) bit shall be set to ZERO. | +| Spectrum bounds upstream | Always set to ZERO. | +| Spectrum shaping upstream | Always set to ZERO. | +| Spectrum bounds downstream | Always set to ZERO. | +| Spectrum shaping downstream | Always set to ZERO. | +| Transmit signal images above the Nyquist frequency | Always set to ZERO. | +| Offset IDFT sample #0 downstream | Always set to ZERO. | +| Offset IDFT sample #0 upstream | Always set to ZERO. | + +**Table B.6 – VTU-O MS message NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of NPar(3) bits | +|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR |

Bit 1: Short loop: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, short loop operation shall be allowed.

Bit 2: Medium loop: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, medium loop operation shall be allowed.

Bit 3: Long loop: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, long loop operation shall be allowed.

Bit 4: FMT-O-P-TREF2: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, the VTU-O shall transmit O-P-TREF symbols during O-P-ECT-LR. If set to ZERO, the VTU-O shall transmit O-P-QUIET symbols during O-P-ECT-LR.

| + +**Table B.7 – VTU-R MS message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|----------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR | Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, indicates that both the VTU-O and the VTU-R shall continue initialization for VDSL2-LR mode as defined in this annex. If set to ZERO, indicates that both the VTU-O and VTU-R shall continue initialization as defined in clause 10. If this bit is set to ONE, then the CE length SPar(2) bit shall be set to ZERO. | +| Upstream spectrum bounds | Always set to ZERO. | +| Upstream spectrum shaping | Always set to ZERO. | +| Upstream spectrum bounds | Always set to ZERO. | +| Upstream spectrum shaping | Always set to ZERO. | +| Transmit signal images above the | Always set to ZERO. | + +**Table B.7 – VTU-R MS message SPar(2) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of SPar(2) bit | +|----------------------------------|---------------------------| +| Nyquist frequency | | +| Offset IDFT sample #0 downstream | Always set to ZERO. | +| Offset IDFT sample #0 upstream | Always set to ZERO. | + +**Table B.8 – VTU-R MS message NPar(3) bit definitions** + +| ITU-T G.994.1 SPar(2) Bit | Definition of NPar(3) bits | +|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Support of VDSL2-LR |

Bit 1: Short loop: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, short loop operation shall be allowed.

Bit 2: Medium loop: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, medium loop operation shall be allowed.

Bit 3: Long loop: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, long loop operation shall be allowed.

Bit 4: FMT-O-P-TREF2: Set to ONE if and only if both the last previous CLR and the last previous CL messages have set this bit to ONE. If set to ONE, the VTU-O shall transmit O-P-TREF symbols during O-P-ECT-LR. If set to ZERO, the VTU-O shall transmit O-P-QUIET symbols during O-P-ECT-LR.

| + +If the ITU-T G.994.1 MS message has the "Support of VDSL2-LR" SPar(2) bit set to ONE, then it shall: + +- indicate use of the mandatory CE Length; +- indicate operation according to a profile other than profile 30a (see Tables 6-1 and Q.1 of [ITU-T G.993.2]); +- have the annex B US0 SPar(2) set to ONE and have one of the 25-138 kHz (A), 25-276 kHz (M) or 120-276 kHz (B) NPar(3) set to ONE. + +Selection of the particular loop operation (short loop, medium loop, or long loop) occurs during the following stages of initialization, as described in clause B.2. The particular loop operation may be selected only if allowed (i.e., if the corresponding ITU-T G.994.1 MS message "Short loop", "Medium loop" or "Long loop" Npar(3) bit is set to ONE)." + +## B.4 Signals sent by the VTU-O during the Channel Discovery and Training phase + +The maximum duration of O-P-VECTOR 0, O-P-VECTOR 1-LR and O-P-VECTOR 1 is defined in clauses B.4.2, B.4.5 and B.4.7, respectively. In addition, if the bit "8192 superframes duration for O-P-VECTOR 1" is enabled in the ITU-T G.994.1 Handshake phase (see clause 10.2), then the sum of the durations of all stages starting from O-P-VECTOR 0 and up to but not including O-P-CHANNEL DISCOVERY V1 shall not exceed $8 \times 1024 \times 257$ symbols. + +A VTU-R indicating "Support of VDSL2-LR mode" in the ITU-T G.994.1 CLR message, shall also indicate support of "8192 superframes duration for O-P-VECTOR 1". + +NOTE – Regular ITU-T G.993.5 lines with the bit "8192 superframes duration for O-P-VECTOR 1" disabled in the ITU-T G.994.1 Handshake phase may initialize in a different joining group that does not include VDSL2-LR lines. + +### **B.4.1 O-P-QUIET 1** + +After the ITU-T G.994.1 Handshake phase, the VTU-O shall start initialization with the O-P-QUIET 1 signal defined in clause 12.3.3.3.1.1 of [ITU-T G.993.2]. + +The duration of O-P-QUIET 1 signal shall be at least 512 but not longer than 1024 symbol periods. + +The O-P-QUIET 1 signal shall be followed by the O-P-VECTOR 0 signal. + +### **B.4.2 O-P-VECTOR 0** + +The O-P-VECTOR 0 signal shall be identical to the O-P-VECTOR 1 signal defined in clause 10.3.3.1. It includes all subcarriers from the downstream SUPPORTEDCARRIERS set. The PSD of the O-P-VECTOR 0 signal shall be derived using the same rules as for the PSD of the O-P-VECTOR 1 signal (see clause 10.3.3.1), except that the aggregate transmit power for the O-P-VECTOR 0 signal shall not exceed the minimum of the maximum aggregate downstream transmit power, as defined for the selected profile in Table 6-1 of [ITU-T G.993.2], and the MAXNOMATPds value configured in the CO-MIB. + +During transmission of the O-P-VECTOR 0 signal, the VCE estimates the downstream FEXT channels from the initializing lines into the vectored lines based on the reported clipped error samples from the VTU-Rs of the vectored lines. From this point on, FEXT cancellation matrices are established in the VTU-Os for all vectored lines in the downstream direction and FEXT from the initializing line into vectored lines is cancelled. + +The duration of O-P-VECTOR 0 is determined by the VTU-O, under VCE control. The VCE may select the duration of O-P-VECTOR 0 appropriately, with the aim to synchronize the start of O-P-PROBING-LR signals on all the VDSL2-LR lines of the vectored group. + +The duration of O-P-VECTOR 0 shall not exceed $M \times 1024 \times 257$ symbols. If the bit "8192 superframes duration for O-P-VECTOR 1" is enabled in the ITU-T G.994.1 Handshake phase (see clause 10.2), then $M = 8$ . Otherwise, $M = 1$ . + +NOTE – With $M = 8$ , the maximum duration of O-P-VECTOR 0 will timeout the maximum duration over all stages starting from O-P-VECTOR 0 and up to but not including O-P-CHANNEL DISCOVERY V1 (see clause B.4). + +The O-P-VECTOR 0 signal shall be followed by the O-P-PROBING-LR signals. + +### **B.4.3 O-P-PROBING-LR** + +The O-P-PROBING-LR shall consist of a number of periodic signals, as defined in clause B.6. These signals are intended to synchronize the VTU-R, to allow it to estimate the length of the line so that it can indicate back to the VTU-O whether the initialization of the line shall continue either in short-medium loop operation (to become a short or medium VDSL2-LR line), or in a long loop operation (for a long VDSL2-LR line). If long loop operation is selected, the VTU-O also receives an indication of the pilot tone assigned by the VTU-R and the required downstream power cut-back (PCB) determined by the VTU-R. + +The O-P-PROBING-LR signals may be transmitted with an IDFT size that is different from the Initial IDFT size indicated in the ITU-T G.994.1 CL message. The IDFT size ( $2N$ ) shall be at least 2048 (i.e., $n \geq 11$ ). + +The PSD of the O-P-PROBING-LR signals shall be as defined in clause B.6.1.1. + +The O-P-PROBING-LR signals shall be followed by the O-P-QUIET 1-LR signal. + +NOTE – While the VTU-O transmits the O-P-PROBING-LR signals, it is recommended that the VCE freezes precoder updates for lines with the VTU-O in the O-SHOWTIME state. + +### **B.4.4 O-P-QUIET 1-LR** + +The O-P-QUIET 1-LR signal shall be identical to the O-P-QUIET 1 signal. + +While transmitting this signal, the VTU-O performs any reconfiguration necessary for the selected continuation of the initialization, either in short-medium loop operation (to become a short or medium VDSL2-LR line) or in long loop operation (for a long VDSL2-LR line). + +The duration of the O-P-QUIET 1-LR signal shall be 64 symbols. + +If the initialization of the line shall be continued in short-medium loop operation, then the O-P-QUIET 1-LR signal shall be followed by the O-P-VECTOR 1 signal defined in clause B.4.7. + +If the initialization of the line shall be continued in long loop operation, then the O-P-QUIET 1-LR signal shall be followed by the O-P-VECTOR 1-LR signal. + +NOTE – While the VTU-O transmits the O-P-QUIET 1-LR signal, it is recommended that the VCE freezes precoder updates for lines with the VTU-O in the O-SHOWTIME state. + +### **B.4.5 O-P-VECTOR 1-LR** + +The O-P-VECTOR 1-LR signal shall be identical to the O-P-VECTOR 1 signal defined in clause 10.3.3.1, except that: + +- it shall include only all subcarriers from the downstream SUPPORTEDCARRIERS set up to subcarrier index 511 (up to about 2.2 MHz); +- its PSD shall be the same as the PSD of the O-P-TRAINING-LR signals (see clause B.7.1.1); +- it is transmitted with an IDFT size ( $2N$ ) that may be different from the initial IDFT size indicated in the ITU-T G.994.1 CL message, but shall be at least 2048 (i.e., $n \geq 11$ ), so that there is no image above the subcarrier with index 511. + +The duration of O-P-VECTOR 1-LR is determined by the VTU-O, under VCE control. The VCE may select the duration of O-P-VECTOR 1-LR appropriately, with the aim to synchronize the start of O-P-TRAINING-LR signals on all the VDSL2-LR lines in long loop operation of the vectored group. + +The duration of O-P-VECTOR 1-LR shall not exceed $M \times 1024 \times 257$ symbols. If the bit "8192 superframes duration for O-P-VECTOR 1" is enabled in the ITU-T G.994.1 Handshake phase (see clause 10.2), then $M = 8$ . Otherwise, $M = 1$ . + +NOTE – With $M = 8$ , the maximum duration of O-P-VECTOR 1-LR will timeout the maximum duration over all stages starting from O-P-VECTOR 0 and up to but not including O-P-CHANNEL DISCOVERY V1 (see clause B.4). + +The O-P-VECTOR 1-LR signal shall be followed by the O-P-TRAINING-LR signals. + +The O-P-VECTOR 1-LR signal is necessary to adopt potential changes in impedance during reconfiguration of the VDSL2-LR line after it has been selected to be in long loop operation. + +NOTE – The VTU-R uses spectrum up to 2.2 MHz during the PROBING stage, and may need to re-configure for short-medium loop operation, which may change its impedance and thus impact precoder settings for lines with the VTU-O in the O-SHOWTIME state. The impact of these changes will be accommodated during transmission of O-P-VECTOR 1. + +### **B.4.6 O-P-TRAINING-LR** + +The O-P-TRAINING-LR signals are defined in clause B.7. + +While the VTU-O transmits the O-P-TRAINING-LR signals, the VTU-R transmits the R-P-TRAINING-LR signals. The O/R-P-TRAINING-LR signals allow the VTU-O and VTU-R to train their echo cancellers (EC) and time domain equalizers (TEQ). The PSD of the O-P-TRAINING-LR signals shall be as defined in clause B.7.1.1. + +After the EC and TEQ training, both VTUs are ready for SOC communications. Therefore, after O/R-P-TRAINING-LR signal exchange is complete, the line continues regular ITU-T G.993.5 initialization, exchanging corresponding messages over SOC. + +The IDFT size during O-P-TRAINING-LR shall be the same as during O-P-VECTOR 1-LR. + +NOTE – While the VTU-O transmits the O-P-TRAINING-LR signals, it is recommended that the VCE freezes precoder updates on subcarriers up to subcarrier index 511. + +The duration of O-P-TRAINING-LR is variable. The maximum duration of O-P-TRAINING-LR shall respect the rule defined in clause B.4. + +The O-P-TRAINING-LR signals shall be followed by the O-P-CHANNEL DISCOVERY V1 signal and the remainder of the channel discovery phase, as defined in clause B.4.8. + +### **B.4.7 O-P-VECTOR 1** + +The O-P-VECTOR 1 signal shall be identical to the O-P-VECTOR 0 signal defined in clause B.4.2. + +The duration of O-P-VECTOR 1 shall not exceed $M \times 1024 \times 257$ symbols. If the bit "8192 superframes duration for O-P-VECTOR 1" is enabled in the ITU-T G.994.1 Handshake phase (see clause 10.2), then $M = 8$ . Otherwise, $M = 1$ . + +NOTE – With $M = 8$ , the maximum duration of O-P-VECTOR 1 will timeout the maximum duration over all stages starting from O-P-VECTOR 0 and up to but not including O-P-CHANNEL DISCOVERY V1 (see clause B.4). + +The O-P-VECTOR 1 signal shall be followed by the O-P-CHANNEL DISCOVERY V1 signal and the remainder of the channel discovery phase, as defined in clause B.4.8. + +### **B.4.8 The G.993.5 Channel Discovery phase** + +If short-medium loop operation is selected in the PROBING stage, the ITU-T G.993.5 Channel Discovery phase shall be applied with the amendments defined in this clause. If long loop operation is selected in the PROBING stage, then the ITU-T G.993.5 Channel Discovery phase shall be applied with the amendments as specified in clause B.8. + +#### **B.4.8.1 O-SIGNATURE (amends clause 12.3.3.2.1.1 of [ITU-T G.993.2])** + +Field #8 "Downstream nominal maximum aggregate transmit power (MAXNOMATPds)" is used to calculate the value of control parameter *MAXNOMATPds*, which determines the maximum wide-band power that the VTU-O is allowed to transmit. The value of the MAXNOMATPds communicated in field #28 shall not exceed the minimum of 20.5 dBm and the MAXNOMATPds value configured in the CO-MIB, regardless of the particular [ITU-T G.993.2] profile selected during the ITU-T G.994.1 Handshake phase of initialization. + +The value of the control parameter *MAXNOMATPds* shall be calculated as the minimum of the maximum aggregate downstream transmit power as defined for the selected profile in Table 6-1 of [ITU-T G.993.2] and the MAXNOMATPds value indicated in the Field #8 of the O-SIGNATURE message. + +NOTE 1 – The attention of the reader is drawn to the fact that the value of the control parameter *MAXNOMATPds* may be different from the value of MAXNOMATPds communicated in O-SIGNATURE, which is not the case for [ITU-T G.993.2]. + +NOTE 2 – The value of the control parameter *MAXNOMATPds* is known to both the VTU-O and VTU-R and does not need to be exchanged from VTU-O to VTU-R. + +#### **B.4.8.2 O-UPDATE (amends clause 12.3.3.2.1.2 of [ITU-T G.993.2])** + +If the ITU-T G.994.1 MS message has the short loop bit set to ZERO, then the highest allowed upstream subcarrier indicated by the VTU-O in O-UPDATE (see Table 12-28 of [ITU-T G.993.2]) + +shall meet the condition for medium loop operation as defined in clause B.4.8.3 (i.e., forced medium loop operation). + +#### **B.4.8.3 O-PRM (amends clause 12.3.3.2.1.3 of [ITU-T G.993.2])** + +If the ITU-T G.994.1 MS message has the medium loop bit set to ONE and if the highest allowed upstream subcarrier indicated by the VTU-O in O-UPDATE (see Table 12-28 of [ITU-T G.993.2]) and the proposed highest downstream subcarrier indicated by the VTU-R in R-UPDATE (see Table 12-35 of [ITU-T G.993.2]) are both equal to or less than the highest subcarrier index defined for DS2 band in the applied bandplan and both do not exceed the value 1971 (8.5 MHz, see Table 6-1 of [ITU-T G.993.2]), then the VDSL2-LR line shall be in medium loop operation. Otherwise, the VDSL2-LR line shall be in short loop operation. + +If the VDSL2-LR line is in medium loop operation, the value of the control parameter *MAXNOMATPds* shall be changed to a value equal to the MAXNOMATPds value indicated in the Field #8 of O-SIGNATURE message. If the VDSL2-LR line is in short loop operation, the value of the control parameter *MAXNOMATPds* shall remain unchanged, as determined in clause B.4.8.1. + +The *MREFPSds* indicated in O-PRM (see Table 12-30 of [ITU-T G.993.2]) shall have an aggregate transmit power that shall not exceed this *MAXNOMATPds* value. + +NOTE – For medium loop operation, the *MREFPSDds* could have an aggregate transmit power that exceeds the maximum aggregate downstream transmit power (as defined in Tables 6-1 and Q.1 of [ITU-T G.993.2]) for the particular [ITU-T G.993.2] profile selected during the ITU-T G.994.1 Handshake phase of initialization. + +### **B.4.9 The ITU-T G.993.5 Training phase** + +If long loop operation is selected in the PROBING stage, then the ITU-T G.993.5 Training phase shall be applied with the amendments defined in clause B.8. If short-medium loop operation is selected in the PROBING stage, the original ITU-T G.993.5 training phase shall be used. + +## **B.5 Signals sent by the VTU-R during the Channel Discovery and Training phase** + +### **B.5.1 R-P-QUIET 1** + +After the ITU-T G.994.1 Handshake phase, the VTU-R shall start initialization with the R-P-QUIET 1 signal defined in clause 12.3.3.3.2.1 of [ITU-T G.993.2]. + +The duration of R-P-QUIET 1 is determined by the VTU-O. Within 64 symbols after the VTU-O ending the first signal of O-P-PROBING-LR (O-P-COMB 2-LR, see clause B.6.1.3), the VTU-R shall end the R-P-QUIET 1 signal. + +The R-P-QUIET 1 signal shall be followed by the R-P-PROBING-LR signals. + +### **B.5.2 R-P-PROBING-LR** + +The R-P-PROBING-LR consists of a number of periodic signals, as defined in clause B.6. + +While receiving the O-P-PROBING-LR signals, the VTU-R shall determine whether the initialization of the line shall continue either in short-medium loop operation (to become a short or medium VDSL2-LR line) or in long loop operation (for a long VDSL2-LR line). In the latter case, the VTU-R shall also assign the pilot tone and determine the minimum downstream power cut-back (PCBds, see Table B.10), if needed. + +The R-P-PROBING-LR signals shall be transmitted with the IDFT size and type of image as indicated by the VTU-R in the "Transmit signal images above the Nyquist frequency" block in the ITU-T G.994.1 CLR message. The IDFT size may be different from the Initial IDFT size indicated in the ITU-T G.994.1 CL message. + +The PSD of the R-P-PROBING-LR signals shall be as defined in clause B.6.2.1. + +The R-P-PROBING-LR signals shall be followed by the R-P-QUIET 1-LR signal. + +### **B.5.3 R-P-QUIET 1-LR** + +The R-P-QUIET 1-LR signal shall be identical to the R-P-QUIET 1 signal. + +While transmitting this signal, the VTU-R performs any reconfiguration necessary for the selected continuation of the initialization, either in short-medium loop operation (to become a short or medium VDSL2-LR line) or as a VDSL2-LR line (for a long VDSL2-LR line). + +The duration of R-P-QUIET 1-LR signal shall be 64 symbol periods. + +If the initialization shall be continued in short-medium loop operation, then the R-P-QUIET 1-LR signal shall be followed by the R-P-QUIET 1 signal defined in clause 10.3.4.1 and the remainder of the channel discovery phase shall be as defined in clause 10.3, except for the changes defined in clauses B.4.8 and B.10.4.1. + +If the initialization shall be continued in long loop operation, then the R-P-QUIET 1-LR signal shall be followed by the R-P-QUIET 2-LR signal. + +### **B.5.4 R-P-QUIET 2-LR** + +The R-P-QUIET 2-LR signal shall be identical to the R-P-QUIET 1 signal. + +The duration of R-P-QUIET 2-LR is determined by the VTU-O. Within 64 symbols after the VTU-O ending the first signal of O-P-TRAINING-LR (O-P-REVERB 1-LR, see clause B.7.1.1), the VTU-R shall end the R-P-QUIET 2-LR signal. + +The R-P-QUIET 2-LR signal shall be followed by the R-P-TRAINING-LR signals. + +### **B.5.5 R-P-TRAINING-LR** + +The R-P-TRAINING-LR signals are defined in clause B.7. + +While the VTU-R transmits the R-P-TRAINING-LR signals, the VTU-O transmits the O-P-TRAINING-LR signals. The O/R-P-TRAINING-LR signals allow the VTU-O and VTU-R to train their echo cancellers (EC) and time domain equalizers (TEQ). The PSD of the R-P-TRAINING-LR signals shall be the same as for the R-P-PROBING-LR signals (see clause B.6.1.1). + +After EC and TEQ training, both VTUs are ready for SOC communications. After O/R-P-TRAINING-LR signal exchange is complete, the line continues regular ITU-T G.993.5 initialization, exchanging corresponding messages over SOC. + +The IDFT size during R-P-TRAINING shall be as indicated by the VTU-R in the "Transmit signal images above the Nyquist frequency" block in the ITU-T G.994.1 CLR message. + +The R-P-TRAINING-LR signals shall be followed by the R-P-QUIET 1 signal defined in clause 10.3.4.1 and the remainder of the channel discovery phase defined in clause 10.3. + +### **B.5.6 The ITU-T G.993.5 Channel Discovery phase** + +If long loop operation is selected in the PROBING stage, then the ITU-T G.993.5 Channel Discovery phase shall be applied with the amendments defined in clause B.8. If short-medium loop operation is selected in the PROBING stage, the ITU-T G.993.5 Channel Discovery phase shall be applied with the amendments defined in clause B.5.6. + +In both cases, the value of the control parameter *MAXNOMATPus* shall be as defined in clause B.10.1.7. + +#### **B.5.6.1 R-UPDATE (amends clause 12.3.3.2.2.2 of [ITU-T G.993.2])** + +If the ITU-T G.994.1 MS message has the short loop bit set to ZERO, then the proposed highest downstream subcarrier indicated by the VTU-R in R-UPDATE (see Table 12-35 of [ITU-T G.993.2]) shall meet the condition for medium loop operation as defined in clause B.4.8.3 (i.e., forced medium loop operation). + +### **B.5.7 ITU-T G.993.5 Training phase** + +If long loop operation is selected in the PROBING stage, then the ITU-T G.993.5 Training phase shall be applied with amendments defined in the clause B.8. If short-medium loop operation is selected in the PROBING stage, the original ITU-T G.993.5 Training phase shall be applied. + +## **B.6 O/R-P-PROBING-LR signal exchange** + +The O/R-P-PROBING-LR signal exchange uses signals defined in ITU-T G.992.5, with the constraint that the duration of signals and the transitions between different signals occurs on boundaries of DMT symbols with CE. This constraint is identical to the constraint defined in clause 12.3.6.1 of [ITU-T G.993.2] to send the O/R-P-PERIODIC signals. Because only the mandatory CE is supported in the VDSL2-LR mode, the duration of each signal is a multiple of 64 symbols with CE (or 69 symbols without CE). + +The O/R-P-PROBING-LR signal exchange is depicted in Figure B.2. + +NOTE – The duration of the O/R-P-PROBING-LR signal exchange is between 1.5 s and 1.9 s. + +### **B.6.1 O-P-PROBING-LR signals** + +#### **B.6.1.1 Transmit PSD of the O-P-PROBING-LR signals** + +The O-P-PROBING-LR transmit PSD (*PROBINGPSDds*) shall be derived from the *NOMPSD* and *log\_tssi* values exchanged in the downstream spectrum bounds and downstream spectrum shaping parameter blocks of the ITU-T G.994.1 CL message during the ITU-T G.994.1 Handshake phase, as defined in clause 8.13.2.4 of [ITU-T G.992.3], and as: + +$$PROBINGPSDds(f) = CL\_NOMPSDds + log\_tssi\_ds(f)$$ + +where *CL\_NOMPSDds* is the *NOMPSDds* indicated by the VTU-O in the ITU-T G.994.1 CL message. The *CL\_NOMPSDds* shall be less than or equal to the *MAXNOMPSDds* configured in the CO-MIB (see clause B.10.1.2). + +The PSD limits for the O-P-PROBING-LR signals shall be the *PSDMASKds*. The *PROBINGPSDds(f)* shall not exceed *PSDMASKds(f)* minus 3.5dB, for all subcarriers in the *SUPPORTEDCARRIERsd* set with indices up to 511. The *PSDMASKds(f)* is defined in Table 7-4 of [ITU-T G.993.2] and shall be derived taking into account the *LIMITMASKds* as defined in clause B.9. + +All subcarriers included in the O-P-PROBING-LR signals shall be transmitted at the *PROBINGPSDds*, with an accuracy of $\pm 1$ dB at the U-O2 reference point. + +The aggregate transmit power for the O-P-PROBING-LR signals shall not exceed the minimum of the maximum aggregate downstream transmit power as defined in clause B.9 for the corresponding annex of [ITU-T G.993.2] and the *MAXNOMATPds* value configured in the CO-MIB. The VTU-O shall determine the value of *CL\_NOMPSDds* and *log\_tssi\_ds* such that the aggregate transmit power of the O-P-PROBING-LR signal shall not exceed the above value. + +NOTE – For long loop operation, the O-P-PROBING-LR signals could have an aggregate transmit power that exceeds the maximum aggregate downstream transmit power (as defined in Tables 6-1 and Q.1 of [ITU-T G.993.2]) for the particular ITU-T G.993.2 profile selected during the ITU-T G.994.1 Handshake phase of initialization. However, this is unlikely to happen since COMB symbols are used in the O-P-PROBING-LR signals. + +#### **B.6.1.2 Symbol definitions for the O-P-PROBING-LR signals** + +The O-P-QUIET symbol is defined as identical to the C-QUIET symbol defined in clause 8.13.3.1.1 of [ITU-T G.992.3]. + +The O-P-COMB symbol shall use the subcarrier set as defined in clause 8.13.3.1.2 of [ITU-T G.992.5]. For the purpose of defining the O-P-COMB subcarrier set, the value *NSCds* shall be set to 512. All O-P-COMB subcarriers with indices that are in the SUPPORTEDCARRIERSDs set with indices up 511 shall be used. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to those subcarriers. The constellation points on those subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2 of [ITU-T G.993.2]. The scrambler shall be used in reset mode (see clause 12.3.6.2.1 of [ITU-T G.993.2]). + +The O-P-ICOMB symbol is defined as identical to the O-P-COMB symbol, except with the value 00 mapped on the same subcarriers. + +All signals consisting of O-P-COMB or O-P-ICOMB symbols shall be implemented as periodic signals, such as O/R-P-PERIODIC 1 (see clause 12.3.6.1 of [ITU-T G.993.2]). + +#### **B.6.1.3 O-P-COMB 2-LR** + +The O-P-COMB 2-LR state is of fixed length. In the O-P-COMB 2-LR state, the VTU-O shall transmit 3648 O-P-COMB symbols. + +The O-P-COMB 2-LR state shall be followed by the O-P-QUIET 3-LR state. + +#### **B.6.1.4 O-P-QUIET 3-LR** + +The O-P-QUIET 3-LR state is of variable length. In the O-P-QUIET 3-LR state, the VTU-O shall transmit a multiple of 64 O-P-QUIET symbols, with a minimum of 256 and a maximum of 960 O-P-QUIET symbols. The O-P-QUIET 3-LR state shall be followed by the O-P-COMB 3-LR state. + +#### **B.6.1.5 O-P-COMB 3-LR** + +The O-P-COMB 3-LR state is of fixed length. In the O-P-COMB 3-LR state, the VTU-O shall transmit 64 O-P-COMB symbols. + +The O-P-COMB 3-LR state shall be followed by the O-P-ICOMB 2-LR state. + +#### **B.6.1.6 O-P-ICOMB 2-LR** + +The O-P-ICOMB 2-LR state is of fixed length. In the O-P-ICOMB 2-LR state, the VTU-O shall transmit 64 O-P-ICOMB symbols. + +The O-P-ICOMB 2-LR state shall be followed by the O-P-QUIET 4-LR state. + +#### **B.6.1.7 O-P-QUIET 4-LR** + +The O-P-QUIET 4-LR state is of variable length. In the O-P-QUIET 4-LR state, the VTU-O shall transmit a multiple of 64 O-P-QUIET symbols, with a minimum of 1152 and a maximum of 1408 O-P-QUIET symbols. + +The VTU-O shall receive and decode the content of the message R-MSG-PCB during this state. + +The VTU-O shall continue to transmit O-P-QUIET symbols until after the VTU-R transitioning to the R-P-QUIET 4-LR state. Within 128 symbols after the VTU-R transitioning to the R-P-QUIET4-LR state, the VTU-O shall transition to the next state. + +If the VTU-O has successfully received the R-P-MSG-PCB message, the O-P-QUIET 4-LR state shall be followed by the O-P-COMB 4-LR state. Otherwise, the VTU-O shall return to the O-SILENT state. + +#### B.6.1.8 O-P-COMB 4-LR + +The O-P-COMB 4-LR state is of fixed length. In the O-P-COMB 4-LR state, the VTU-O shall transmit 64 O-P-COMB symbols. + +The O-P-COMB 4-LR signal serves as an acknowledgement of the successful reception of the R-P-MSG-PCB message. + +The O-P-COMB 4-LR state shall be followed by the ICOMB 4-LR state. + +#### B.6.1.9 O-P-ICOMB 4-LR + +The O-P-ICOMB 4-LR state is of fixed length. In the O-P-ICOMB 4-LR state, the VTU-O shall transmit 64 O-P-ICOMB symbols. + +The O-P-ICOMB 4-LR state shall be followed by the O-P-MSG-PCB-LR state. + +#### B.6.1.10 O-P-MSG-PCB-LR + +In downstream direction, the transmit power shall be further adjusted by a power cutback value determined by the VTU-O during the PROBING stage, based on the maximal used downstream subcarriers requested by the VTU-R in the R-P-MSG-PCB-LR message. + +The O-P-MSG-PCB-LR state is of fixed length. In the O-P-MSG-PCB-LR state, the VTU-O shall transmit 512 symbols of O-P-COMB or O-P-ICOMB to modulate the O-P-MSG-PCB-LR message. The O-P-MSG-PCB-LR message conveys the VTU-O determined power cutback level for the downstream direction. + +The O-P-MSG-PCB-LR message $m$ is defined by: + +$$m = \{ m_7, \dots, m_0 \}$$ + +Bits shall be defined as shown in Table B.9. + +**Table B.9 – Bit definition for the O-P-MSG-PCB-LR message** + +| Bit index | Parameter | Definition | +|-----------|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 3...0 | O-PCB_DS | VTU-O final downstream power cutback in dB, represented as an unsigned integer in the 0 to 15 range (4-bit value with MSB in bit 3 and LSB in bit 0) (see Note). | +| 7...4 | Reserved by ITU-T | Shall be set to 0 and ignored by the receiver. | + +NOTE – This power cutback shall be further used instead of the minimum downstream power cutback indicated in R-MSG-PCB-LR message. The value shall be lower than or equal to the R-MIN\_PCB\_DS requested by the VTU-R. If the VTU-R indicated that the line shall continue the initialization in short-medium loop operation, this field shall be set to 0 and ignored by the VTU-R. + +The 8 bits $m_0$ – $m_7$ shall be transmitted in 512 symbol periods ( $m_0$ first and $m_7$ last). A ZERO bit shall be transmitted as 64 consecutive O-P-COMB symbols (1 bit per 69 symbols without CE). A ONE bit shall be transmitted as 64 consecutive O-P-ICOMB symbols. + +The O-P-MSG-PCB-LR state also indicates to the VTU-R that the PROBING stage is complete. + +The O-P-MSG-PCB-LR state shall be followed by the O-P-QUIET 1-LR state. + +### B.6.2 R-P-PROBING-LR signals + +#### B.6.2.1 Transmit PSD of the R-P-PROBING-LR signals + +The R-P-PROBING-LR transmit PSD (*PROBINGPSDus*) shall be derived from the *NOMPSD* and *log\_tssi* values exchanged in the upstream spectrum bounds and upstream spectrum shaping + +parameter blocks of the ITU-T G.994.1 CLR message during the ITU-T G.994.1 Handshake phase, as defined in clause 8.13.2.4 of [ITU-T G.992.3], and as: + +$$PROBINGPSDus(f) = MIN(CL\_NOMPSDus, CLR\_NOMPSDus) - PCBus + \log\_tssi\_us(f),$$ + +where *CL\_NOMPSDus* is the *NOMPSDus* indicated by the VTU-O in the CL message and *CLR\_NOMPSDus* is the *NOMPSDus* indicated by the VTU-R in the ITU-T G.994.1 CLR message. The *CL\_NOMPSDus* shall be less than or equal to the MAXNOMPSDus configured in the CO-MIB (see clause B.10.1.2). + +The PSD limits for the R-P-PROBING-LR signals shall be the PSDMASKus. The *PROBINGPSDus(f)* shall not exceed PSDMASKus(*f*) minus 3.5 dB for all subcarriers in the SUPPORTEDCARRIERus set in the US0 band [*foL*, *foH*]. The PSDMASKus(*f*) is defined in Table 7-4 of [ITU-T G.993.2] and shall be derived taking into account the LIMITMASKus as defined in clause B.9. + +The VTU-R shall apply a *PCBus* = 10dB if the VTU-R determines that the line is short or medium, and shall apply a *PCBus* = 0dB if the VTU-R determines that the line is long. The VTU-R shall evaluate the length of the line before sending the first active symbol of R-P-PROBING-LR signal (see Figure B.2). The VTU-R shall use these rules of setting the *PCBus* regardless whether or not short, medium or long loop operation is allowed during the ITU-T G.994.1 Handshake phase (see clause B.3). + +The transmit PSD of the R-P-LINEPROBE-LR signal shall not exceed the *PROBINGPSDus*. + +All subcarriers included in the R-P-PROBING-LR signals shall be transmitted at the *PROBINGPSDus* lowered with *PCBus*, with an accuracy of $\pm 1$ dB at the U-R2 reference point. + +The aggregate transmit power for the R-P-PROBING-LR signals shall not exceed the value of the control parameter *MAXNOMATPus* as defined in clause B.10.1.7. The VTU-O shall determine the value of *CL\_NOMPSDus* such that for any valid setting of *CLR\_NOMPSDus*, *PCBus* and *log\_tssi\_us* chosen by the VTU-R, the aggregate transmit power of the R-P-PROBING-LR signal shall not exceed the above value. + +#### **B.6.2.2 Symbol definitions for the R-P-PROBING-LR signals** + +The R-P-QUIET symbol is defined as identical to the R-QUIET symbol defined in clause 8.13.3.2.1 of [ITU-T G.992.3]. + +The R-P-COMB symbol shall use the subcarrier set as defined in clause 8.13.3.2.2 of [ITU-T G.992.5]. For the purpose of defining the R-P-COMB subcarrier set, the value *NSCus* shall be set to 32 or 64, in accordance with the US0 PSD mask defined in clause B.9.2.2. All R-P-COMB subcarriers with indices in the passband of the US0 PSD mask shall be used. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to those subcarriers. The constellation points on these subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2 of [ITU-T G.993.2]. The scrambler shall be used in reset mode (see clause 12.3.6.2.1 of [ITU-T G.993.2]). + +The R-P-ICOMB symbol is defined as identical to the R-P-COMB symbol, except with the value 00 mapped on the same subcarriers. + +All signals consisting of R-P-COMB or R-P-ICOMB symbols shall be implemented as periodic signals, such as O/R-P-PERIODIC 1 (see clause 12.3.6.1 of [ITU-T G.993.2]). + +#### **B.6.2.3 R-P-COMB 2-LR** + +The R-P-COMB 2-LR state is of fixed length. In the R-P-COMB 2-LR state, the VTU-R shall transmit 256 R-P-COMB symbols. + +The R-P-COMB 2-LR state shall be followed by the R-P-ICOMB 1-LR state if the VTU-R desires to use the R-P-LINEPROBE-LR state. Otherwise the R-P-COMB 2-LR state shall be followed by the R-P-QUIET 3-LR state. + +#### **B.6.2.4 R-P-ICOMB 1-LR** + +The R-P-ICOMB 1-LR state is of fixed length. In the R-P-COMB 1-LR state, the VTU-R shall transmit 64 R-P-ICOMB symbols. + +The R-P-ICOMB 1-LR state shall be followed by the R-P-LINEPROBE-LR state. + +#### **B.6.2.5 R-P-LINEPROBE-LR** + +The R-P-LINEPROBE-LR state is of fixed length. In the R-P-LINEPROBE-LR state, the VTU-R shall transmit a vendor-discretionary signal with a duration of 512 symbol periods. + +The R-P-LINEPROBE-LR state shall be followed by the R-P-QUIET 3-LR state. + +#### **B.6.2.6 R-P-QUIET 3-LR** + +The R-P-QUIET 3-LR state is of variable length. In the R-P-QUIET 3-LR state, the VTU-R shall transmit a multiple of 64 R-P-QUIET symbols, with a minimum of 128 and a maximum of 320 R-P-QUIET symbols. + +The VTU-R shall continue to transmit R-P-QUIET symbols until after the VTU-O transitioning to O-P-QUIET 4-LR. Within 128 symbols after the VTU-O transitioning to O-P-QUIET 4-LR, the VTU-R shall transition to the next state. + +The R-P-QUIET 3-LR state shall be followed by the R-P-COMB 3-LR state. + +#### **B.6.2.7 R-P-COMB 3-LR** + +The R-P-COMB 3-LR state is of fixed length. In the R-P-COMB 3-LR state, the VTU-R shall transmit 64 R-P-COMB symbols. + +The R-P-COMB 3-LR state shall be followed by the R-P-ICOMB 2-LR state. + +#### **B.6.2.8 R-P-ICOMB 2-LR** + +The R-P-ICOMB 2-LR state is of fixed length. In the R-P-ICOMB 2-LR state, the VTU-R shall transmit 64 R-P-ICOMB symbols. + +The R-P-ICOMB 2-LR state shall be followed by the R-P-MSG-PCB-LR state. + +#### **B.6.2.9 R-P-MSG-PCB-LR** + +In downstream direction, the transmit power shall be reduced by a power cutback value. The minimum downstream power cutback value is determined by the VTU-R during the PROBING stage. + +NOTE – The VTU-R can consider its receiver dynamic range as determined by observing O-P-COMB 2-LR, and the local line conditions determined by the optional R-P-LINEPROBE-LR when determining the minimum downstream power cutback value. + +The R-P-MSG-PCB-LR state is of fixed length. In the R-P-MSG-PCB-LR state, the VTU-R shall transmit 1536 symbols of R-P-COMB or R-P-ICOMB to modulate the R-P-MSG-PCB message. The R-P-MSG-PCB message conveys the VTU-R determined minimum downstream power cutback for the downstream direction, and the downstream pilot tone used for timing recovery during different states. + +The R-P-MSG-PCB message $m$ is defined by: + +$$m = \{ m_{23}, \dots, m_0 \},$$ + +where the bits shall be defined as shown in Table B.10. + +**Table B.10 – Bit definition for the R-P-MSG-PCB-LR message** + +| Bit index | Parameter | Definition | +|-----------|---------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| [3:0] | R-MIN_PCB_DS | VTU-R minimum downstream power cutback in dB, represented as an unsigned integer in the 0 to 15 range (4-bit value with MSB in bit 3 and LSB in bit 0). | +| [12:4] | O-P-PILOT | Subcarrier index of downstream pilot tone, represented as an unsigned integer in the 32 to 511 range (9-bit value with MSB in bit 12 and LSB in bit 4) (see Notes 1 and 4). | +| 13 | OPTYPE | Shall be set to 0 if the initialization of the line shall continue in short-medium loop operation (to become a short or medium VDSL2-LR line).
Shall be set to 1 if the initialization of the line shall continue in long loop operation (a long VDSL2-LR line).
(see Notes 2 and 3) | +| [22:14] | LAST_TONE_DS | Subcarrier index of the highest transmitted downstream frequency in the TRAINING stage expressed as unsigned integer (9-bit value with MSB in bit 22 and LSB in bit 14) (Notes 4 and 5). | +| 23 | Reserved by ITU-T | Shall be set to 0 and ignored by the receiver. | + +NOTE 1 – The indicated *O-P-PILOT* value shall be used as the index of the O-P-TREF pilot subcarrier (see clause B.7.1.4) to support/recovery of the VTU-R timing during the O-P-TRAINING stage. +NOTE 2 – If *OPTYPE* bit is set to 0, the VTU-O shall ignore all other parameters of the message. +NOTE 3 – If the ITU-T G.994.1 MS message has the long loop bit set to ZERO, then the *OPTYPE* bit shall be set to ZERO. If the ITU-T G.994.1 MS message has both the short loop bit and medium loop bit set to ZERO, then the *OPTYPE* bit shall be set to ONE (i.e., forced long loop operation). +NOTE 4 – If the *OPTYPE* bit is set to 0 (the line shall continue the initialization in short-medium loop operation), this field shall be set to 491. +NOTE 5 – The valid values of *LAST\_TONE\_DS* are those associated with subcarriers from the *O-P-COMB* symbol set, as defined in clause B.6.1.2, and the additional valid value of 511. + +The 24 bits $m_0$ – $m_{23}$ shall be transmitted in 1536 symbol periods ( $m_0$ first and $m_{23}$ last). A ZERO bit shall be transmitted as 64 consecutive R-P-COMB symbols (1 bit per 69 symbols without CE). A ONE bit shall be transmitted as 64 consecutive R-P-ICOMB symbols. + +The R-P-MSG-PCB-LR state shall be followed by the R-P-QUIET 4-LR state. + +#### B.6.2.10 R-P-QUIET 4-LR + +The R-P-QUIET 4-LR state is of variable length. In the R-P-QUIET 4-LR state, the VTU-R shall transmit a multiple of 64 R-P-QUIET symbols, with a minimum of 64 and a maximum of 192 R-P-QUIET symbols. + +If the VTU-R has successfully detected the O-P-COMB 4-LR signal, the R-P-QUIET 4-LR state shall be followed by the R-P-QUIET 1-LR state. Otherwise, the VTU-R shall return to the R-SILENT state. + +### B.6.3 Timeline of O/R-P-PROBING-LR signals + +The signal exchange is depicted in Figure B.2. + +![Timeline of O/R-P-PROBING-LR signals showing a sequence of signal blocks with durations in symbols with CE (values in parentheses are without CE).](f2b561f8d2d2b8402379552179d9fbef_img.jpg) + +| | | | | +|---------------|----------------|-------------|----------------------------------------------| +| | O-P-VECTOR 0 | | R-P-QUIET 1 | +| 3648 (3933) | O-P-COMB 2-LR | | | +| | O-P-QUIET 3-LR | ≤ 64 (69) | | +| ≥ 256 (276) | | | R-P-COMB 2-LR 256 (276) | +| ≤ 960 (1035) | | | R-P-ICOMB 1-LR 0 or 64 (69) | +| | | | R-P-LINEPROBE-LR 0 or 512 (552) | +| | | ≤ 64 (69) | R-P-QUIET 3-LR
≥ 128 (138)
≤ 320 (345) | +| 64 (69) | O-P-COMB 3-LR | | | +| 64 (69) | O-P-ICOMB 2-LR | | | +| | O-P-QUIET 4-LR | ≤ 128 (138) | R-P-COMB 3-LR 64 (69) | +| ≥ 1664 (1794) | | | R-P-ICOMB 2-LR 64 (69) | +| ≤ 1920 (2070) | | | R-P-MSG-PCB-LR 1536 (1656) | +| | | ≤ 128 (138) | R-P-QUIET 4-LR
≥ 640 (690)
≤ 768 (828) | +| 64 (69) | O-P-COMB 4-LR | | | +| 64 (69) | O-P-ICOMB 4 | | | +| 512 (552) | O-P-MSG-PCB-LR | | | +| | O-P-QUIET 1-LR | | R-P-QUIET 1-LR | + +Timeline of O/R-P-PROBING-LR signals showing a sequence of signal blocks with durations in symbols with CE (values in parentheses are without CE). + +G.993.5(15)-Amd.2(17)\_FB.2 + +**Figure B.2 – Timeline of O/R-P-PROBING-LR signals** + +In Figure B.2, signal durations are expressed in symbols with CE (values in parenthesis are the signal durations expressed in symbols without CE). Signals shaded in grey are parts of the previous and the following stages of initialization (see Figure B.1). + +## B.7 O/R-P-TRAINING-LR signal exchange + +The O/R-P-TRAINING-LR signal exchange is depicted in Figure B.4 and uses signals defined in [ITU-T G.992.5], with the constraint that the transitions between different signals occur on boundaries of DMT symbols with CE. The duration of each signal is a multiple of 64 symbols with CE (or 69 symbols without CE). + +NOTE – The O/R-P-TRAINING-LR signal exchange allows training of the TEQ and EC before full duplex transmission. The duration of that exchange is between 1.9s and 9.7s. + +### B.7.1 O-P-TRAINING-LR signals + +#### B.7.1.1 Transmit PSD of the O-P-TRAINING-LR signals + +The O-P-TRAINING-LR transmit PSD (*TRAININGPSDDs*) shall be derived from the *NOMPSD* and *log\_tssi* values exchanged in the downstream spectrum bounds and downstream spectrum + +shaping parameter blocks of the ITU-T G.994.1 CL message during the ITU-T G.994.1 Handshake phase, as defined in clause 8.13.2.4 of [ITU-T G.992.3], and the *O-PCB\_DS* value indicated by the VTU-O during the PROBING stage, as: + +$$TRAININGPSDds(f) = NOMPSDds - PCBds + ceiled\_log\_tssi\_ds(f),$$ + +with + +$$ceiled\_log\_tssi\_ds(f) = MIN(log\_tssi\_ds(f) + PCBds, 0 \text{ dB}),$$ + +and + +$$PCBds = O-PCB\_DS.$$ + +All subcarriers included in the O-P-TRAINING-LR signals shall be transmitted at the *TRAININGPSDds*, with an accuracy of $\pm 1\text{dB}$ at the U-O2 reference point. + +The PSD limits for the O-P-TRAINING-LR signals shall be the PSDMASKds. The *TRAININGPSDds(f)* shall not exceed PSDMASKds(*f*) minus 3.5dB, for all subcarriers in the SUPPORTEDCARRIERds set with indices up to 511. The PSDMASKds is defined in Table 7-4 of [ITU-T G.993.2] and shall be derived taking into account the LIMITMASKds as defined in clause B.9 using the highest sub-carrier with the index equal to *LAST\_TONE\_DS* value indicated by the VTU-R during the PROBING stage. + +The aggregate transmit power for the O-P-TRAINING-LR signals shall not exceed the minimum of the maximum aggregate downstream transmit power as defined in clause B.9 for corresponding annex of [ITU-T G.993.2] and the MAXNOMATPds value configured in the CO-MIB. + +The VTU-O shall determine the value of *CL\_NOMPSDds*, *log\_tssi\_ds*, and *PCBds*, such that the aggregate transmit power of the O-P-TRAINING-LR signals shall not exceed the above value. + +#### B.7.1.2 Symbol definitions for the O-P-TRAINING-LR signals + +The O-P-REVERB symbol shall contain all subcarriers up to index 511. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to these subcarriers. The constellation points on these subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2 of [ITU-T G.993.2]. The scrambler shall be used in reset mode (see clause 12.3.6.2.1 of [ITU-T G.993.2]). + +The O-P-QUIET symbol is the same as defined for the O-P-PROBING-LR. + +The O-P-TREF symbol shall be a single tone symbol. Only the *O-P-PILOT* subcarrier index specified by the VTU-R in the R-P-MSG-PCB message (i.e., the O-P-TREF pilot tone) shall be transmitted. The O-P-TREF pilot tone shall modulate the 4-QAM {0,0} constellation point. No power shall be transmitted on the other subcarriers (i.e., $X_i = Y_i = 0$ ). + +The O-P-SEGUE symbol is defined as identical to the O-P-REVERB symbol, except with the value 00 mapped to the same subcarriers. + +All signals consisting of O-P-REVERB, O-P-SEGUE or O-P-TREF symbols shall be implemented as periodic signals, such as O/R-P-PERIODIC 1 (see clause 12.3.6.1 of G.993.2). + +The O-P-PILOT symbol is defined as identical to the symbols transmitted during the O-P-PILOT 1 of [ITU-T G.993.2] (see clause 12.3.3.3.1.4 of [ITU-T G.993.2]). Only the *O-P-PILOT* subcarrier index specified by the VTU-R in the R-P-MSG-PCB-LR message (i.e., the O-P-TREF pilot tone) shall be transmitted during the O-P-PILOT symbol. + +#### B.7.1.3 O-P-REVERB 0-LR + +The O-P-REVERB 0-LR state is of fixed length. In the O-P-REVERB 0-LR state, the VTU-O shall transmit 3648 O-P-REVERB symbols. + +During the O-P-REVERB 0-LR state, the VTU-R restores loop timing, adjusts the AFE and acquires downstream symbol timing. + +The O-P-REVERB 0-LR state shall be followed by the O-P-QUIET 5-LR state. + +#### **B.7.1.4 O-P-QUIET 5-LR** + +The O-P-QUIET 5-LR state is of fixed length. In the O-P-QUIET 5-LR state, the VTU-O shall transmit 128 O-P-QUIET symbols. + +During the O-P-QUIET 5-LR state, the VTU-O detects R-P-REVERB 1-LR and then prepares for bidirectional transmission. + +The O-P-QUIET 5-LR state shall be followed by the O-P-REVERB 1-LR state. + +#### **B.7.1.5 O-P-REVERB 1-LR** + +The O-P-REVERB 1-LR state is of fixed length. In the O-P-REVERB 1-LR state, the VTU-O shall transmit 512 O-P-REVERB symbols. + +During the O-P-REVERB 1-LR state, the VTU-O may fine-tune its AGC (while the VTU-R is in the R-P-REVERB 1-LR state) and do adaptive AFE algorithms. + +The O-P-REVERB 1-LR state shall be followed by the O-P-TREF 1-LR state. + +#### **B.7.1.6 O-P-TREF 1-LR** + +The O-P-TREF 1-LR state is of variable length. In the O-P-TREF 1-LR state, the VTU-O shall transmit a minimum of 512 and a maximum of 15872 O-P-TREF symbols. + +During the O-P-TREF 1-LR state, VTU-O may train its TEQ. + +The O-P-TREF 1-LR state shall be followed by the O-P-REVERB 2-LR state. + +#### **B.7.1.7 O-P-REVERB 2-LR** + +The O-P-REVERB 2-LR state is of fixed length. In the O-P-REVERB 2-LR state, the VTU-O shall transmit 64 O-P-REVERB symbols. + +Transition to O-P-REVERB 2-LR state indicates to the VTU-R that VTU-O completed its TEQ training. + +The O-P-REVERB 2-LR state shall be followed by the O-P-ECT-LR state. + +#### **B.7.1.8 O-P-ECT-LR** + +The O-P-ECT-LR state is of fixed length. In the O-P-ECT-LR state, the VTU-O shall transmit a vendor-discretionary signal with a duration of 512 symbol periods. + +During this state, the VTU-O may train its echo canceller. + +The O-P-ECT-LR state shall be followed by the O-P-REVERB 3-LR state. + +#### **B.7.1.9 O-P-REVERB 3-LR** + +The O-P-REVERB 3-LR state is of variable length. In the O-P-REVERB 3-LR state, the VTU-O shall transmit a minimum of 448 and a maximum of 15936 O-P-REVERB symbols. + +The O-P-REVERB 3-LR state provides VTU-R with a training signal (presumably, for the TEQ). + +The VTU-O shall continue to transmit O-P-REVERB symbols until after the VTU-R transitioning to the R-P-REVERB 3-LR state. Within 64 symbols after the VTU-R transitioning to the R-P-REVERB 3-LR state, the VTU-O shall transition to the next state. + +In case the VTU-R has indicated in the ITU-T G.994.1 CLR message that it requires the VTU-O to transmit O-P-TREF symbols during the R-P-ECT-LR state (i.e., has set the "FMT-O-P-TREF2" bit to ONE), the O-P-REVERB 3-LR state shall be followed by the O-P-TREF 2-LR state. In case the VTU-R has indicated that it requires the VTU-O to transmit O-P-QUIET symbols during the R-P-ECT-LR state (i.e., has set the "FMT-O-P-TREF2" bit to ZERO), the O-P-REVERB 3-LR state shall be followed by the O-P-QUIET 6-LR state. + +#### **B.7.1.10 O-P-TREF 2-LR** + +The O-P-TREF 2-LR state is of fixed length. In the O-P-TREF 2-LR state, the VTU-O shall transmit 576 O-P-TREF symbols. + +The O-P-TREF 2-LR state facilitates EC training at the VTU-R. The VTU-O shall ignore the signal transmitted by the VTU-R during this state. + +The O-P-TREF 1-LR state shall be followed by the O-P-REVERB 4-LR state. + +#### **B.7.1.11 O-P-QUIET 6-LR** + +The O-P-QUIET 6-LR state is of fixed length. In the O-P-QUIET 6-LR state, the VTU-O shall transmit 576 O-P-QUIET symbols. + +The VTU-O shall ignore the signal transmitted by the VTU-R during this state. + +The O-P-QUIET 6-LR state shall be followed by the O-P-REVERB 4-LR state. + +#### **B.7.1.12 O-P-REVERB 4-LR** + +The O-P-REVERB 4-LR state is of fixed length. In the O-P-REVERB 4-LR state, the VTU-O shall transmit 1024 O-P-REVERB symbols. + +During the O-P-REVERB 4-LR state, the VTU-O can adjust its parameters for bidirectional transmission. + +The O-P-REVERB 4-LR state shall be followed by the O-P-SEGUE 1-LR state. + +#### **B.7.1.13 O-P-SEGUE 1-LR** + +The O-P-SEGUE 1-LR state is of fixed length. In the O-P-SEGUE1-LR state, the VTU-O shall transmit 64 O-P-SEGUE symbols. The first symbol of O-P-SEGUE 1-LR is used as reference time point to facilitate alignment between the timing of VDSL2-LR training and the G.993.5 Channel Discovery (see clause B.8.1). The O-P-SEGUE 1-LR state shall be followed by the O-P-PILOT-LR state. + +#### **B.7.1.14 O-P-PILOT-LR** + +The O-P-PILOT-LR phase is intended to equalize the duration of the TRAINING phase between different lines of the vectored group. In the O-P-PILOT-LR state, the VTU-O shall transmit an integer number of O-P-PILOT symbols. The duration of the O-P-PILOT-LR state is variable, under the control of the VCE, and can be in the range from 128 to 31360 symbols. + +The O-P-PILOT is a non-periodic signal. The alignment of the O-P-PILOT symbols and the O-P-SEGUE 1-LR state shall use two reference points associated with the IDFT sample #0 of specific symbols. The IDFT sample #0 is defined as the first sample of the block of 2N time samples generated by the IDFT. + +The first reference point shall be the IDFT sample #0 of the first symbol of the O-P-SEGUE 1-LR state, and the second reference point is the IDFT sample #0 of the first symbol of the O-P-PILOT-LR state, as shown in the Figure B.3. + +![Figure B.3: Reference samples for alignment of downstream symbols between the O-SEGUE 1-LR state and O-P-PILOT-LR state. The diagram shows two symbol structures. The top structure is for the O-P-SEGUE1-LR (First symbol) state, showing a block of 2N samples with a cyclic prefix of length beta. The IDFT sample #0 is marked at the start of the main block. The bottom structure is for the O-P-PILOT-LR state, showing a block of 2N samples with a cyclic prefix of length L_CP and a cyclic suffix of length L_CS. The IDFT sample #0 is marked at the start of the main block, with an offset of L_CP - beta from the start of the cyclic prefix.](199607ec43a5b7ad43b1896e152e742b_img.jpg) + +G.993.5(15)-Amd.2(17)\_FB.3 + +Figure B.3: Reference samples for alignment of downstream symbols between the O-SEGUE 1-LR state and O-P-PILOT-LR state. The diagram shows two symbol structures. The top structure is for the O-P-SEGUE1-LR (First symbol) state, showing a block of 2N samples with a cyclic prefix of length beta. The IDFT sample #0 is marked at the start of the main block. The bottom structure is for the O-P-PILOT-LR state, showing a block of 2N samples with a cyclic prefix of length L\_CP and a cyclic suffix of length L\_CS. The IDFT sample #0 is marked at the start of the main block, with an offset of L\_CP - beta from the start of the cyclic prefix. + +**Figure B.3 – Reference samples for alignment of downstream symbols between the O-SEGUE 1-LR state and O-P-PILOT-LR state** + +The time offset expressed in samples between those reference points modulo the period of a DMT symbol with CE, i.e., $2N+L_{CE}$ samples, shall be as indicated by the VTU-O in the ITU-T G.994.1 Spar(2) codepoint "offset IDFT sample #0" indicated by the VTU-O. The parameter "offset IDFT sample #0" shall be an integer number of samples at the rate of 4.416 MHz. + +NOTE – The value of this offset is equal to $L_{CP}-\beta$ which is always less than or equal to $L_{CE}$ , see Figure B.4. Knowledge of that offset by the receiver, allows VTU-R to derive the symbol timing during the O-P-PILOT-LR and transition into ITU-T G.993.5 Channel Discovery phase with timing acquired in the VDSL2-LR TRAINING stage. This, in turn, allows the re-use of TEQ settings and other transceiver settings obtained during the VDSL2-LR TRAINING stage. + +The VCE uses O-P-PILOT-LR state to align the start of O-P-CHANNEL DISCOVERY V1 on all VDSL2-LR lines (regardless of short, medium or long loop operation type) and the regular ITU-T G.993.5 lines. The actual duration of the O-P-PILOT-LR state depends on the durations of the O-P-TREF 1-LR and O-P-REVERB 3-LR states: the sum of the durations of O-P-PILOT-LR, O-P-TREF 1-LR, and O-P-REVERB 3-LR states shall not exceed the sum of the maximum durations of O-P-TREF 1-LR and O-P-REVERB 3-LR and the minimum duration of O-P-PILOT-LR, i.e., $15872+15936+128 = 31936$ symbols. + +The O-P-PILOT-LR state shall be followed by the O-P-CHANNEL DISCOVERY V1 signal and the remainder of the ITU-T G.993.5 Channel Discovery phase with the amendments as specified in clause B.8. + +### B.7.2 R-P-TRAINING-LR signals + +#### B.7.2.1 Transmit PSD of the R-P-TRAINING-LR signals + +The R-P-TRAINING-LR transmit PSD ( $TRAININGPSDus$ ) shall be identical to the $PROBINGPSDus$ : + +$$TRAININGPSDus(f) = PROBINGPSDus(f)$$ + +All subcarriers included in the R-P-TRAINING-LR signals shall be transmitted at the $TRAININGPSDus$ , with an accuracy of $\pm 1\text{dB}$ at the U-O2 reference point. + +The PSD limits for the R-P-TRAINING-LR signals shall be the PSDMASKus. The PSDMASKus is defined in Table 7-4 of [ITU-T G.993.2] and shall be derived taking into account the LIMITMASKus as defined in clause B.9. + +The maximum aggregate transmit power for the R-P-TRAINING-LR signals shall not exceed the value of the control parameter *MAXNOMATPus* as defined in clause B.10.1.7. The VTU-O shall determine the value of *CL\_NOMPSDus* such that for any valid setting of *CLR\_NOMPSDus*, *PCBus* and *log\_tssi\_us* chosen by the VTU-R, the aggregate transmit power of the R-P-TRAINING-LR signal shall not exceed the above value. + +#### **B.7.2.2 Symbol definitions for the R-P-TRAINING-LR signals** + +The R-P-QUIET symbol is the same as defined for the R-P-PROBING-LR. + +The R-P-REVERB symbol shall contain all subcarriers up to index *NSCus-1*, with *NSCus* as defined in clause B.6.2.2. These subcarriers shall be modulated by 4-QAM. The value 11 shall be mapped to these subcarriers. The constellation points on these subcarriers shall be rotated based on the 2-bit number provided by the quadrant scrambler described in clause 12.3.6.2 of [ITU-T G.993.2]. The scrambler shall be used in reset mode (see clause 12.3.6.2.1 of [ITU-T G.993.2]). + +The R-P-SEGUE symbol is defined as identical to the R-P-REVERB symbol, with the value 00 mapped to the same subcarriers. + +All signals consisting of R-P-REVERB or R-P-SEGUE symbols shall be implemented as periodic signals, such as O/R-P-PERIODIC 1 (see clause 12.3.6.1 of [ITU-T G.993.2]). + +#### **B.7.2.3 R-P-REVERB 1-LR** + +The R-P-REVERB 1-LR state is of fixed length. In the R-P-REVERB 1-LR state, the VTU-O shall transmit 640 R-P-REVERB symbols. + +During the R-P-REVERB 1-LR state, the VTU-R may fine-tune its AGC, does timing recovery and other adaptive AFE algorithms. + +The R-P-REVERB 1-LR state shall be followed by the R-P-REVERB 2-LR state. + +#### **B.7.2.4 R-P-REVERB 2-LR** + +The R-P-REVERB 2-LR state is of variable length. In the R-P-REVERB 2-LR state, the VTU-R shall transmit a minimum of 384 and a maximum of 16000 R-P-REVERB symbols. + +The R-P-REVERB 2-LR state provides VTU-O with a training signal (presumably, for the TEQ). + +The VTU-R shall continue to transmit R-P-REVERB symbols until after the VTU-O transitioning to the O-P-REVERB 2-LR state. Within 64 symbols after the VTU-O transitioning to the O-P-REVERB 2-LR state, the VTU-R shall transition to the next state. + +The R-P-REVERB 2-LR state shall be followed by the R-P-QUIET 5-LR state. + +#### **B.7.2.5 R-P-QUIET 5-LR** + +The R-P-QUIET 5-LR state is of variable length. In the R-P-QUIET 5-LR state, the VTU-R shall transmit a minimum of 1024 and a maximum of 16384 R-P-QUIET symbols. The number of symbols transmitted in the R-P-QUIET 5-LR state shall be a multiple of 512 symbols. However, the last R-P-QUIET symbol transmitted in the R-P-QUIET 5-LR state may be shortened by any integer number of samples (at the sample clock frequency $2N \times \Delta f$ , as defined in clause 10.4.4 of [ITU-T G.993.2]) to accommodate transmitter-to-receiver frame alignment. + +During this state, the VTU-R shall ignore the signal transmitted by the VTU-O during the O-P-ECT-LR state. While the VTU-O is in the O-P-REVERB 3-LR state, the VTU-R may measure the downstream channel characteristics and train its TEQ. The VTU-R transitions to the next state when it has completed the necessary training. + +The R-P-QUIET 5-LR state shall be followed by the R-P-REVERB 3-LR state. + +#### **B.7.2.6 R-P-REVERB 3-LR** + +The R-P-REVERB 3-LR state is of fixed length. In the R-P-REVERB 3-LR state, the VTU-R shall transmit 64 R-P-REVERB symbols. + +Transition to R-P-REVERB 3-LR state indicates to the VTU-O that the VTU-R completed its TEQ training. It also provides a time marker for the R-P-ECT-LR state. + +The R-P-REVERB 3-LR state shall be followed by the R-P-ECT-LR state. + +#### **B.7.2.7 R-P-ECT-LR** + +The R-P-ECT-LR state is of fixed length. In this state, the VTU-R shall transmit a vendor-discretionary signal with a duration of 512 symbol periods. + +During this state, the VTU-R may train its echo canceller. + +The R-P-ECT-LR state shall be followed by the R-P-REVERB 4-LR state. + +#### **B.7.2.8 R-P-REVERB 4-LR** + +The R-P-REVERB 4-LR state is of fixed length. In this state, the VTU-R shall transmit 1024 R-P-REVERB symbols. + +During the R-P-REVERB 4-LR state, the VTU-R can adjust its parameters for bidirectional transmission. + +The R-P-REVERB 4-LR state shall be followed by the R-P-SEGUE 1-LR state. The transition from the R-P-REVERB 4-LR state to the R-P-SEGUE 1-LR state is a time marker for the start time of R-P-QUIET 1 and for the VTU-R being ready to receive the O-SIGNATURE message. + +#### **B.7.2.9 R-P-SEGUE 1-LR** + +The R-P-SEGUE 1-LR state is of fixed length. In the R-P-SEGUE 1-LR state, the VTU-R shall transmit 64 R-P-SEGUE symbols. The first symbol of R-P-SEGUE 1-LR is used as reference point to keep the synchronization between VDSL-LR training and the ITU-T G.993.5 Channel Discovery (see clause B.8.3). + +The transition to the next state is a time marker for the end of the TRAINING stage and indicates that the VTU-R shall be ready to receive the O-SIGNATURE message. + +The R-P-SEGUE 1-LR state shall be followed by the ITU-T G.993.5 R-P-QUIET1 state. + +### B.7.3 Timeline of O/R-P-TRAINING-LR signals + +The signal exchange is depicted in Figure B.4. + +![Timeline diagram of O/R-P-TRAINING-LR signals showing signal exchange between O-P and R-P sides. The diagram consists of two vertical columns of signal blocks. The left column (O-P side) includes blocks for O-P-VECTOR 1-LR, O-P-REVERB 0-LR, O-P-QUIET 5-LR, O-P-REVERB 1-LR, O-P-TREF 1-LR, O-P-REVERB 2-LR, O-P-ECT-LR, O-P-REVERB 3-LR, O-P-TREF 2-LR/O-P-QUIET 6-LR, O-P-REVERB 4-LR, O-P-SEGUE 1-LR, O-P-PILOT-LR, and O-P-CHANNEL DISCOVERY V1. The right column (R-P side) includes blocks for R-P-QUIET 2-LR, R-P-REVERB 1-LR, R-P-REVERB 2-LR, R-P-QUIET 5-LR (last symbol may be shortened), R-P-REVERB 3-LR, R-P-ECT-LR, R-P-REVERB 4-LR, R-P-SEGUE 1-LR, R-P-QUIET 1, and R-P-CHANNEL DISCOVERY 1. Dashed lines indicate timing relationships and durations between signals. Grey shaded blocks represent parts of previous and following stages.](3c0be9369e1f99f7f820fda3f9d676e6_img.jpg) + +| | | | | | +|--------------------------------|----------------------------------|----------------------|--------------------------------------------------|--------------------------------------------| +| | O-P-VECTOR 1-LR | | R-P-QUIET 2-LR | | +| 3648 (3933) | O-P-REVERB 0-LR | | | | +| 128 (138) | O-P-QUIET 5-LR | ≤ 64 (69) | | | +| 512 (552) | O-P-REVERB 1-LR | | R-P-REVERB 1-LR | 640 (690) | +| ≥ 512 (552)
≤ 15872 (17112) | O-P-TREF 1-LR | | R-P-REVERB 2-LR | ≥ 384 (414)
≤ 16000 (17250) | +| 64 (69) | O-P-REVERB 2-LR | ≤ 64 (69) | | | +| 512 (552) | O-P-ECT-LR | | | | +| ≥ 448 (483)
≤ 15936 (17181) | O-P-REVERB 3-LR | | R-P-QUIET 5-LR
(last symbol may be shortened) | ≥ 1024 (1104)
≤ 16384 (17664) | +| | | ≤ 64 (69) | R-P-REVERB 3-LR | 64 (69) | +| 576 (621) | O-P-TREF 2-LR/
O-P-QUIET 6-LR | | R-P-ECT-LR | 512 (552) | +| 1024 (1104) | O-P-REVERB 4-LR | | R-P-REVERB 4-LR | 1024 (1104) | +| 64 (69) | O-P-SEGUE 1-LR | | R-P-SEGUE 1-LR | 64 (69) | +| ≥ 128 (138)
≤ 31360 (33810) | O-P-PILOT-LR | | | | +| | O-P-CHANNEL
DISCOVERY V1 | O-SIGNATURE received | R-P-QUIET 1 | Variable integer number of symbols with CE | +| | | | R-P-CHANNEL
DISCOVERY 1 | | + +Timeline diagram of O/R-P-TRAINING-LR signals showing signal exchange between O-P and R-P sides. The diagram consists of two vertical columns of signal blocks. The left column (O-P side) includes blocks for O-P-VECTOR 1-LR, O-P-REVERB 0-LR, O-P-QUIET 5-LR, O-P-REVERB 1-LR, O-P-TREF 1-LR, O-P-REVERB 2-LR, O-P-ECT-LR, O-P-REVERB 3-LR, O-P-TREF 2-LR/O-P-QUIET 6-LR, O-P-REVERB 4-LR, O-P-SEGUE 1-LR, O-P-PILOT-LR, and O-P-CHANNEL DISCOVERY V1. The right column (R-P side) includes blocks for R-P-QUIET 2-LR, R-P-REVERB 1-LR, R-P-REVERB 2-LR, R-P-QUIET 5-LR (last symbol may be shortened), R-P-REVERB 3-LR, R-P-ECT-LR, R-P-REVERB 4-LR, R-P-SEGUE 1-LR, R-P-QUIET 1, and R-P-CHANNEL DISCOVERY 1. Dashed lines indicate timing relationships and durations between signals. Grey shaded blocks represent parts of previous and following stages. + +G.993.5(15)-Amd.2(17)\_FB.4 + +Figure B.4 – Timeline of O/R-P-TRAINING-LR signals + +In Figure B.4, signals durations are expressed in symbols with CE (values in parenthesis are signals durations expressed in symbols without CE). Signals shaded in grey are parts of the previous and the following stages of initialization (see Figure B.1). + +NOTE – Training of TEQ can be shortened by the receiver in case TEQ is further trained during the VDSL2 initialization. With shortest TEQ training, the duration of this stage is about 1.9s. + +## B.8 ITU-T G.993.5 Channel Discovery phase and Training phase in long loop operation + +This clause contains additional requirements on the ITU-T G.993.5 Channel Discovery phase and Training phase that apply if the long loop operation of VDSL2-LR is selected (see clauses B.4.8, B.4.9, B.5.6 and B.5.7). + +The setting of the transmit path between the IDFT output and the corresponding U-interface of both the VTU-R and VTU-O that was established during the TRAINING stage shall be kept unchanged during the ITU-T G.993.5 Channel Discovery phase and Training phase. The IDFT size and type of image used during the ITU-T G.993.5 Channel Discovery and Training phases shall be the same as those used during the TRAINING stage. + +### B.8.1 ITU-T G.993.5 Channel Discovery phase in long loop operation + +The SUPPORTEDCARRIERsDs set shall be limited to subcarrier index 511. + +The SUPPORTEDCARRIERsUs set shall be limited to subcarrier index 31 for US0 type A, and to subcarrier index 63 for US0 types B and M. + +#### B.8.1.1 Transition to ITU-T G.993.5 Channel Discovery phase + +In the downstream direction, symbols in ITU-T G.993.5 Channel Discovery phase shall be aligned with symbols in O-P-PILOT-LR. + +In the upstream, the transition from VDSL2-LR TRAINING stage to ITU-T G.993.5 Channel Discovery phase shall be aligned using two reference points associated with the IDFT sample #0 of specific symbols. The IDFT sample #0 is defined as the first sample of the block of $2N$ time samples generated by the IDFT. + +The first reference point shall be the IDFT sample #0 of the first symbol of the R-P-SEGUE 1-LR state and the second reference point shall be the IDFT sample #0 of the first symbol of the R-P-CHANNEL DISCOVERY 1 signal, as shown in the Figure B.5. + +![Figure B.5: Reference samples for alignment of upstream symbols between the VDSL2-LR TRAINING stage and ITU-T G.993.5 Channel Discovery phase. The diagram shows two horizontal rectangular blocks representing DMT symbols. The top block is labeled 'O/R-P-SEGUE1-LR (First symbol)'. It has a total length indicated as 2N. A yellow vertical bar marks 'IDFT sample #0' at an offset of beta from the start of the block. The bottom block is labeled 'O-P-CHANNEL-DISCOVERY-V1 or R-P-CHANNEL-DISCOVERY 1'. It shows a cyclic prefix (L_CP), a main body (2N), and a cyclic suffix (L_CS). A yellow vertical bar marks 'IDFT sample #0' within the main body, at an offset of L_CP - beta from the start of the 2N block. Arrows indicate lengths for beta, 2N, L_CP, and L_CS.](0db2dd2a5c02140f5b395569f17ab91d_img.jpg) + +Figure B.5: Reference samples for alignment of upstream symbols between the VDSL2-LR TRAINING stage and ITU-T G.993.5 Channel Discovery phase. The diagram shows two horizontal rectangular blocks representing DMT symbols. The top block is labeled 'O/R-P-SEGUE1-LR (First symbol)'. It has a total length indicated as 2N. A yellow vertical bar marks 'IDFT sample #0' at an offset of beta from the start of the block. The bottom block is labeled 'O-P-CHANNEL-DISCOVERY-V1 or R-P-CHANNEL-DISCOVERY 1'. It shows a cyclic prefix (L\_CP), a main body (2N), and a cyclic suffix (L\_CS). A yellow vertical bar marks 'IDFT sample #0' within the main body, at an offset of L\_CP - beta from the start of the 2N block. Arrows indicate lengths for beta, 2N, L\_CP, and L\_CS. + +**Figure B.5 – Reference samples for alignment of upstream symbols between the VDSL2-LR TRAINING stage and ITU-T G.993.5 Channel Discovery phase** + +The time offset expressed in samples between those reference points modulo the period of a DMT symbol with CE, i.e., $2N+L_{CE}$ samples, shall be as indicated by the VTU-R in the ITU-T G.994.1 Spar(2) codepoint "offset IDFT sample #0". The parameter "offset IDFT sample #0" indicated by the VTU-R shall be an integer number of samples at the rate of 276 kHz. + +NOTE – The value of this offset is equal to $L_{CP}-\beta$ , which is always less than or equal to $L_{CE}$ , see Figure B.5. Knowledge of that offset by the VTU-O, allows to derive the symbol timing during the ITU-T G.993.5 Channel Discovery phase from the one acquired in the VDSL2-LR TRAINING stage. This, in turn, allows the re-use TEQ settings and other transceiver settings obtained during the VDSL2-LR TRAINING stage. + +#### **B.8.1.2 Use of PILOT during R-P-LINEPROBE** + +If the ITU-T G.993.5 R-P-LINEPROBE signal is requested, the VTU-O shall transmit O-P-PILOT 1 and transition to O-P-PERIODIC 1 640 symbols after the end of transmission of O-P-SYNCHRO 1. The O-P-PILOT 1 shall use the tone index indicated during the PROBING stage. + +#### **B.8.1.3 Replacement of R-P-VECTOR signals** + +As upstream crosstalk cancelling is not active when the long loop operation of VDSL2-LR is selected, the R-P-VECTOR signals are removed or replaced by other signals. + +The R-P-VECTOR 1 signal shall be replaced by R-P-CHANNEL DISCOVERY 1 with SOC sending R-IDLE until the O-P-SYNCHRO-V1 signal is received. After the O-P-SYNCHRO-V1 signal is received the VTU-R shall sent R-IDLE at least for the duration of 512 symbols before transmitting R-MSG 1. + +#### **B.8.1.4 O-SIGNATURE (amends clause 12.3.3.2.1.1 of [ITU-T G.993.2])** + +Field #8 "Downstream nominal maximum aggregate transmit power (MAXNOMATPds)" indicates the value of the control parameter *MAXNOMATPds*, which determines the maximum wide-band power that the VTU-O is allowed to transmit. The value of the *MAXNOMATPds* shall not exceed the minimum of the maximum aggregate downstream transmit power as defined in clause B.9 for the corresponding annex of [ITU-T G.993.2] and the MAXNOMATPds value configured in the CO-MIB, regardless of the particular [ITU-T G.993.2] profile selected during the ITU-T G.994.1 Handshake phase of initialization. + +#### **B.8.1.5 PSD adjustments during ITU-T G.993.5 Channel Discovery phase** + +The PSD adjustments defined in ITU-T G.993.5 Channel Discovery phase include potential changes of the downstream highest used subcarrier and the actual downstream transmit PSD, which may result in a different downstream transmit PSD than the one defined during the PROBING stage. To avoid changes in the transmission channel and corresponding degradations in the tuning of the TEQ, the mentioned adjustment of the PSD shall be done exclusively in frequency domain. + +### **B.8.2 ITU-T G.993.5 Training phase in long loop operation** + +During the transition to the ITU-T G.993.5 Training phase, the VTU-R shall keep symbol timing. To facilitate loop timing, the quiet symbols of O-P-VECTOR 1-1 shall be replaced by symbols containing a single subcarrier with the index of the downstream pilot tone indicated in the R-P-MSG-PCB message. The pilot tone shall be modulated with the constellation point (0,0). + +To keep the position of the IDFT sample #0 between the Channel Discovery and the Training phases in upstream, the duration of R-P-QUIET V1 shall be an integer number of DMT symbols. + +#### **B.8.2.1 Replacement of R-P-VECTOR signals** + +The R-P-VECTOR 1-1 signal shall not be sent, i.e, the first signal of transceiver training phase is R-P-TRAINING 1. + +The R-P-VECTOR 1-2 signal shall be replaced by R-P-TRAINING 1-2. The R-P-TRAINING 1-2 signal shall be identical to R-P-TRAINING 1. + +The sync symbols in the R-P-VECTOR 2 shall be replaced by R-P-TRAINING 2 symbols with the extended SOC channel activated. + +## B.9 Definition of limit PSD masks + +This clause defines limit PSD masks and maximum aggregate transmit power (ATP) requirements applicable to VDSL2-LR mode in long loop operation. These requirements apply to the TRAINING-LR stage, the remainder of initialization and the SHOWTIME state. + +### B.9.1 Operation according to Annex A [ITU-T G.993.2] + +VDSL2-LR mode according to Annex A of [ITU-T G.993.2] is not defined. + +### B.9.2 Operation according to Annex B of [ITU-T G.993.2] + +#### B.9.2.1 Downstream Limit PSD mask and maximum aggregate transmit power + +The US0 PSD type is selected in the ITU-T G.994.1 MS message. The corresponding LIMITMASKds for VDSL2-LR mode shall be as defined in Table B.7A of [ITU-T G.993.2] for PSD masks B8-11 (for US0 type A), B8-12 (for US0 type B) and B8-17 (for US0 type M), with flat extension at $-100$ dBm/Hz from 3.925 MHz to 30 MHz and flat extension at $-110$ dBm/Hz above 30 MHz, and with the modification defined in Table B.11. + +The maximum aggregate downstream transmit power (as referred in clauses B.6.1.1 and B.8.1.4) shall be 20.5 dBm, independent of the VDSL2 profile and US0 type selected in the ITU-T G.994.1 Handshake phase. + +**Table B.11 – Modification of the LIMITMASKds for VDSL2-LR mode** + +| Frequency (kHz) | VDSL2-LR LIMITMASKds (dBm/Hz) | +|-------------------------------------------------------------------------------------|-------------------------------| +| $f_i$ | $-36.50$ | +| $f_i + 138$ | $-33.50$ | +| 948.75 | $-33.50$ | +| 1104 | $-36.50$ | +| NOTE – The value $f_i$ is 138 kHz for US0 type A and 276 kHz for US0 types B and M. | | + +#### B.9.2.2 Upstream limit PSD mask + +The US0 PSD type is selected in the ITU-T G.994.1 MS message. The corresponding LIMITMASKus for VDSL2-LR mode shall be as defined in Table B.6A of [ITU-T G.993.2] for PSD masks B8-11 (for US0 type A), B8-12 (for US0 type B) and B8-17 (for US0 type M), with flat extension at $-100$ dBm/Hz from 686 kHz to 30 MHz and flat extension at $-110$ dBm/Hz above 30 MHz. + +The *NSCus* shall be set to 32 for US0 type A and to 64 for US0 types B and M. + +### B.9.3 Operation according to Annex C of [ITU-T G.993.2] + +VDSL2-LR mode according to Annex C of [ITU-T G.993.2] is not defined. + +### B.9.4 Operation according to Annex N of [ITU-T G.993.2] + +VDSL2-LR mode according to Annex N of [ITU-T G.993.2] is not defined. + +## B.10 Management + +This clause defines the CO-MIB configuration, status, and inventory parameters specific to the VDSL2-LR mode. These parameters shall be supported if the VTU-O supports VDSL2-LR mode. + +### **B.10.1 Configuration parameters** + +#### **B.10.1.1 VDSL2-LR enable (VDSL2-LR\_ENABLE)** + +The configuration parameter VDSL2-LR\_ENABLE (see clause 7.3.1.16.1 of [ITU-T G.997.1]) specifies for the line which VDSL2-LR operation types are allowed. It is defined as a bitmap, with following types: + +- Short loop: Short loop operation according to this annex is allowed. +- Medium loop: Medium loop operation according to this annex is allowed. +- Long loop: Long loop operation according to this annex is allowed. + +If none of the operation types are allowed, then the VDSL2-LR mode (i.e., operation according to this annex) is "disabled". If at least one of the operation types is allowed, then the VDSL2-LR mode (i.e., operation according to this annex) is "enabled" (see Table B.1). + +#### **B.10.1.2 Downstream maximum nominal power spectral density (MAXNOMPSDds)** + +The configuration parameter MAXNOMPSDds (see clause 7.3.1.2.1 of [ITU-T G.997.1]) specifies for the line the maximum value of the *NOMPSDds* (used to determine the *PROBINGPSDds*, see clause B.6.1.1) as indicated by the VTU-O in the downstream spectrum bounds in the ITU-T G.994.1 CL message. + +#### **B.10.1.3 Upstream maximum nominal power spectral density (MAXNOMPSDus)** + +The configuration parameter MAXNOMPSDus (see clause 7.3.1.2.2 of [ITU-T G.997.1]) specifies for the line the maximum value of the *NOMPSDus* (used to determine the *PROBINGPSDus*, see clause B.6.2.1) as indicated by the VTU-O in the upstream spectrum bounds in the ITU-T G.994.1 CL message. + +#### **B.10.1.4 Downstream PSD Mask (MIBMASKds) (amends clause 7.2.1.1 of [ITU-T G.993.2])** + +The configuration parameter MIBMASKds (see clause 7.3.1.2.9 of [ITU-T G.997.1]) represents the MIB PSD mask and shall lie at or below the maximum of the Limit PSD mask specified in the selected annex of [ITU-T G.993.2] and, if the VDSL2-LR mode is "enabled" (see clause B.10.1.1), the limit PSD mask defined in clause B.9. Its definition shall be under the network management control (a MIB-controlled mechanism), as defined in [ITU-T G.997.1]. + +The breakpoints used to construct the MIB PSD mask shall be specified so that the minimum of the limit PSD mask specified in the selected annex and the MIB PSD mask can be constructed using no more than 32 breakpoints in the frequency ranges in which the MIB PSD mask is specified. + +#### **B.10.1.5 VDSL2 PSD mask class selection (CLASSMASK)** + +If the VDSL2-LR mode is "enabled" (see clause B.10.1.1), then the configuration parameter CLASSMASK (see clause 7.3.1.2.15 of [ITU-T G.997.1]) shall be set to one of the Annex B classmasks 997-M2x, 998-M2x, 998ADE-M2x, 998E35-M2x or 998ADE35-M2x. + +#### **B.10.1.6 Downstream maximum nominal aggregate transmit power (MAXNOMATPds)** + +The configuration parameter MAXNOMATPds is defined in the CO-MIB (see clause 7.3.1.2.3 of [ITU-T G.997.1]) and specifies: + +- an upperbound to the downstream aggregate transmit power during PROBING for all operation types (short loop, medium loop and long loop operation); +- an upperbound to the downstream aggregate transmit power during TRAINING for long loop operation; +- an upperbound to the downstream aggregate transmit power during O-P-VECTOR 1 for short-medium loop operation; + +- an upperbound to the control parameter *MAXNOMATPds* in O-SIGNATURE for all operation types (short loop, medium loop and long loop operation); and +- an upperbound to the recalculated control parameter *MAXNOMATPds* for the determination of MREFPSDds in ITU-T G.993.5 Channel analysis and exchange phase for medium loop operation. + +The MAXNOMATPds setting in the CO-MIB shall not exceed 20.5 dBm. + +NOTE – In this annex, the MAXNOMATPds setting in the CO-MIB may exceed the maximum aggregate downstream transmit power specified in Table 6.1 of [ITU-T G.993.2]. + +#### **B.10.1.7 Upstream maximum nominal aggregate transmit power (*MAXNOMATPus*)** + +The control parameter *MAXNOMATPus* is determined by the maximum aggregate upstream transmit power specified in Table 6-1 of [ITU-T G.993.2]. + +NOTE – There is no configuration parameter MAXNOMATPus defined in the CO-MIB (see Table 7.15 of [ITU-T G.997.1]). + +### **B.10.2 Status parameters** + +#### **B.10.2.1 VDSL2-LR actual operation type (VDSL2-LR\_ACTOPTYPE)** + +The status parameter VDSL2-LR\_ACTOPTYPE (see clause 7.5.1.44.1 of [ITU-T G.997.1]) reports the line's actual operation type (regardless whether this selection is autonomous by the VTU-R or forced through the CO-MIB). + +The valid values are: + +- No operation type selected: Operation without this annex. +ITU-T G.994.1 MS message has VDSL2-LR Spar(2) bit set to 0. +- Short loop: Short loop operation according to this annex. +ITU-T G.994.1 MS message has VDSL2-LR Spar(2) bit set to 1 and short-medium loop operation is selected in the PROBING stage and the condition for short loop operation (defined in clause B.4.8.3) is met. +- Medium loop: Medium loop operation according to this annex. +ITU-T G.994.1 MS message has VDSL2-LR Spar(2) bit set to 1 and short-medium loop operation is selected in the PROBING stage and the condition for medium loop operation (defined in clause B.4.8.3) is met. +- Long loop: Long loop operation according to this annex. +ITU-T G.994.1 MS message has VDSL2-LR Spar(2) bit set to 1 and long loop operation is selected in the PROBING stage. + +### **B.10.3 Inventory parameters** + +#### **B.10.3.1 VDSL2-LR support (VDSL2-LR\_SUPPORT\_O/R)** + +The VDSL2-LR\_SUPPORT\_O (see clause 7.4.14.1 of [ITU-T G.997.1]) and VDSL2-LR\_SUPPORT\_R (see clause 7.4.14.1 of [ITU-T G.997.1]) inventory parameters report, for the VTU-O and the VTU-R respectively, whether VDSL2-LR mode is not supported (set to 0) or supported (set to 1). + +### **B.10.4 Test parameters** + +#### **B.10.4.1 Test parameter group size** + +If the "Support of VDSL2-LR" bit was set to ONE in the last previous ITU-T G.994.1 MS message, the group size shall be determined according to the equation in clause 11.4.1 of [ITU-T G.993.2], + +with $\theta$ equal to the highest subcarrier index in the MEDLEY set for test parameters measured during the Channel Discovery phase and for test parameters measured during other phases. + +NOTE – This clause applies to the VDSL2-LR mode, regardless whether short, medium or long loop operation is selected. + +## **B.11 Nominal aggregate transmit power (NOMATP) (replaces clause 10.3.4.2.1 of [ITU-G.993.2])** + +NOTE – Unless otherwise specified, references in this clause refer to [ITU-T G.993.2]. + +The nominal aggregate transmit power (NOMATP) shall be computed by the following equation: + +$$\text{NOMATP} = 10 \log_{10} \Delta f + 10 \log_{10} \left( \sum_{i \in \text{MEDLEY set}} \left( 10^{\frac{\text{MREFPSD}[i]}{10}} g_i^2 \right) \right),$$ + +where $\text{MREFPSD}[i]$ and $g_i$ are, respectively, the values of $\text{MREFPSD}$ in dBm/Hz and gain (linear scale) for subcarrier $i$ from the MEDLEY set (see clause 12.3.3.2.1.3), and $\Delta f$ is the subcarrier spacing in Hz. + +The downstream NOMATP (NOMATPds) shall be computed for subcarriers from the downstream MEDLEY set (MEDLEYds). The upstream NOMATP (NOMATPus) shall be computed for subcarriers from the upstream MEDLEY set (MEDLEYus). + +The maximum NOMATPds during ITU-T G.993.5 Channel analysis and exchange phase and during showtime is determined by the control parameter *MAXNOMATPds*. The value of this control parameter is derived during initialization based on the CO-MIB configuration parameter *MAXNOMATPds*, the value of the *MAXNOMATPds* indicated in the Field #8 of O-SIGNATURE message, as well as the operation type (short loop, medium loop, or long loop operation). + +The $g_i$ settings at the VTU-O and VTU-R shall be such that the values of NOMATPds and NOMATPus do not exceed, respectively, the control parameter *MAXNOMATPds* and *MAXNOMATPus*. + +# Appendix I + +## Crosstalk channel modelling + +(This appendix does not form an integral part of this Recommendation.) + +## I.1 Scope + +This appendix provides information on stochastic models for a MIMO FEXT coupling channel in digital subscriber line (DSL) transmission systems operating on twisted-pair cables. For a number of DSL systems, the FEXT coupling among them can be modelled as a MIMO system. + +The models are derived using a statistical analysis of measurements of ingress energy into pairs of a cable from other pairs in the same cable. The data on which the models are based was gathered from measurements of actual loop plant deployed in various regions in the world. + +## I.2 Purpose + +The purpose of this appendix is to provide the industry with a tool for simulating FEXT coupling among multiple DSL lines. + +## I.3 MIMO crosstalk channel model A + +A model for the crosstalk channel for North America and Europe can be found in [b-ATIS-0600024]. This model is based on data gathered from measurements of actual loop plant deployed in North America and Europe. [b-ATIS-0600024] defines a MIMO crosstalk channel model based on these measurements and includes justification for the model. + +## I.4 MIMO crosstalk channel model C + +The data on which this model is based was gathered from measurements of actual loop plant deployed in Japan. + +### I.4.1 Assumptions to crosstalk model + +The crosstalk model is based upon a 0.4 mm (in diameter) polyethylene (PE) insulated cable called a colour coded polyethylene (CCP) cable. The pair binding structure applied to the PE insulated cable is given in Figure I.1, where pair numbers, #1-#10, are attached. In the Figure, a quad is formed by twisting four insulated conductors (two pairs), and a binder group called a unit is formed by binding five quads (ten pairs). Although a PE insulated cable contains one to several units, we can ignore the effect of inter unit crosstalk for simplicity, as inter unit crosstalk is much smaller than intra unit crosstalk. Then, a single unit of ten pairs (five quads) of the PE insulated cable is applied to the crosstalk model. + +![Diagram of a cable model showing a 10-pair unit (5 quads) and a quad (2 pairs). The 10-pair unit contains pairs #1-#10 arranged in five quads: #1+#2, #3+#4, #5+#6, #7+#8, and #9+#10. The quad contains pairs #1a, #1b, #2a, and #2b. Dashed lines connect the 10-pair unit to the quad. Below the diagram, text labels identify the components: '10-pair unit (5 quads) #1-#10: pair number' and 'Quad (2 pairs) (a, b): one pair'. A reference code 'G.993.5(15)_FI.1' is also present.](5ee80a63ec53c60d7306b5a44984afcf_img.jpg) + +10-pair unit (5 quads) +#1-#10: pair number + +Quad (2 pairs) +(a, b): one pair +G.993.5(15)\_FI.1 + +10-pair unit (5 quads) +#1-#10: pair number + +Quad (2 pairs) +(a, b): one pair + +Diagram of a cable model showing a 10-pair unit (5 quads) and a quad (2 pairs). The 10-pair unit contains pairs #1-#10 arranged in five quads: #1+#2, #3+#4, #5+#6, #7+#8, and #9+#10. The quad contains pairs #1a, #1b, #2a, and #2b. Dashed lines connect the 10-pair unit to the quad. Below the diagram, text labels identify the components: '10-pair unit (5 quads) #1-#10: pair number' and 'Quad (2 pairs) (a, b): one pair'. A reference code 'G.993.5(15)\_FI.1' is also present. + +**Figure I.1 – Cable model (0.4 mm PE insulated cable)** + +It is known that the probability density function (PDF) of crosstalk coupling (attenuation) losses in dB is a normal distribution with an average expressed by $M$ (dB) and a standard deviation expressed by $\sigma$ (dB). There are three inter pair location relationships in the unit of the PE insulated cable, which are intra quad, adjacent quad, and every second quad. So, there are three kinds of the population of the crosstalk coupling losses in the unit. The average $M_k$ (dB) [ $k=1, 2, 3$ ] and the standard deviation $\sigma_k$ (dB) [ $k=1, 2, 3$ ] of the FEXT coupling losses are given in Table I.1, where the indices, $k=1, 2, 3$ , correspond to three inter pair location relationships in the unit that form each population. + +**Table I.1 – FEXT average and standard deviation** + +| Item | $k=1$ | $k=2$ | $k=3$ | +|------------------------------------|------------|---------------|-------------------| +| | Intra quad | Adjacent quad | Every second quad | +| FEXT average $M_k$ | 69.2 (dB) | 74.2 (dB) | 75.7 (dB) | +| FEXT standard deviation $\sigma_k$ | 6.56 (dB) | 8.15 (dB) | 7.38 (dB) | + +NOTE – The value of $M_k$ (dB) is given as the value of FEXT loss at $f=f_{FEXT}=160 \cdot 10^3$ (Hz) and $d=d_{FEXT}=1 \cdot 10^3$ (m). + +### I.4.2 Generation of a sample value for FEXT coupling loss + +FEXT coupling loss random samples, $XT_k(i)$ (dB) [ $k=1, 2, 3$ ], between any two pairs in the unit are given in Table I.2 in the form of the 10-by-10 matrix, where the index " $k$ " shows the same as in Table I.1, and the index " $i$ " shows that a different value can be given. It is assumed that the crosstalk from the interfering pair ( $\#m$ ) to the interfered pair ( $\#n$ ) is identical to the crosstalk from the interfering pair ( $\#n$ ) to the interfered pair ( $\#m$ ). Therefore, two sample group values are symmetric with respect to the diagonal line in Table I.2. Consequently, there can be a maximum of five different sample values for $XT_1(i)$ ( $k=1$ ), a maximum of twenty different sample values for $XT_2(i)$ ( $k=2$ ), and a maximum of twenty different sample values for $XT_3(i)$ ( $k=3$ ). + +**Table I.2 – FEXT loss sample** + +| I-ed \ I-ing | #1 | #2 | #3 | #4 | #5 | #6 | #7 | #8 | #9 | #10 | +|--------------|--------------------------|--------------------------|--------------------------|--------------------------|--------------------------|--------------------------|--------------------------|--------------------------|--------------------------|--------------------------| +| #1 | | XT1(1) | XT 2 (1) | XT 2 (2) | XT 3 (1) | XT 3 (2) | XT 3 (3) | XT 3 (4) | XT 2 (3) | XT 2 (4) | +| #2 | XT1(1) | | XT 2 (5) | XT 2 (6) | XT 3 (5) | XT 3 (6) | XT 3 (7) | XT 3 (8) | XT 2 (7) | XT 2 (8) | +| #3 | XT 2 (1) | XT 2 (5) | | XT1(2) | XT 2 (9) | XT 2 (10) | XT 3 (9) | XT 3 (10) | XT 3 (11) | XT 3 (12) | +| #4 | XT 2 (2) | XT 2 (6) | XT1(2) | | XT 2 (11) | XT 2 (12) | XT 3 (13) | XT 3 (14) | XT 3 (15) | XT 3 (16) | +| #5 | XT 3 (1) | XT 3 (5) | XT 2 (9) | XT 2 (11) | | XT1(3) | XT 2 (13) | XT 2 (14) | XT 3 (17) | XT 3 (18) | +| #6 | XT 3 (2) | XT 3 (6) | XT 2 (10) | XT 2 (12) | XT1(3) | | XT 2 (15) | XT 2 (16) | XT 3 (19) | XT 3 (20) | +| #7 | XT 3 (3) | XT 3 (7) | XT 3 (9) | XT 3 (13) | XT 2 (13) | XT 2 (15) | | XT1(4) | XT 2 (17) | XT 2 (18) | +| #8 | XT 3 (4) | XT 3 (8) | XT 3 (10) | XT 3 (14) | XT 2 (14) | XT 2 (16) | XT1(4) | | XT 2 (19) | XT 2 (20) | +| #9 | XT 2 (3) | XT 2 (7) | XT 3 (11) | XT 3 (15) | XT 3 (17) | XT 3 (19) | XT 2 (17) | XT 2 (19) | | XT1(5) | +| #10 | XT 2 (4) | XT 2 (8) | XT 3 (12) | XT 3 (16) | XT 3 (18) | XT 3 (20) | XT 2 (18) | XT 2 (20) | XT1(5) | | + +I-ed: Interfered pair number +I-ing: Interfering pair number + +When generating a random sample $XT_k(i)$ (dB), assuming the cumulative distribution point of $Q$ (%) of the generated sample value is useful. The $XT_k(i)$ (dB) with the cumulative distribution point of $Q$ (%) is given below, assuming a normal distribution with the average $M_k$ (dB) and the standard deviation $\sigma_k$ (dB) given in Table I.1. Table I.3 gives an example calculated by the equations below. + +$$XT_k(i) = M_k + \Delta_k(i)$$ + +$$\Delta_k(i) = \rho_i \sigma_k$$ + +$$pdf(u) = \frac{1}{\sqrt{2\pi}} e^{-\frac{u^2}{2}}$$ + +$$Q(\rho_i) = \int_{\rho_i}^{\infty} pdf(u) du$$ + +where $k = 1, 2, 3$ , + +when $k = 1, i = 1, 2, 3, \dots, \max(5)$ + +when $k = 2, i = 1, 2, 3, \dots, \max(20)$ + +when $k = 3, i = 1, 2, 3, \dots, \max(20)$ + +$M_k$ (dB): average of FEXT coupling losses at $f = f_{EXT}$ and $d = d_{EXT}$ , see Table I.1 + +$\sigma_k$ (dB): standard deviation of FEXT coupling losses, see Table I.3. + +**Table I.3 – Example of random sample $XT_k(i)$ with cumulative distribution point of $Q$ (%)** + +| Cumulative distribution point (%) | $\rho_i$ | $XT_k(i)$ (dB) | | | +|-----------------------------------|----------|-------------------------|-------------------------|-------------------------| +| | | k=1 | k=2 | k=3 | +| | | Intra quad | Adjacent quad | Every second quad | +| $Q(\rho_i)=0.01(\%)$ | 3.72 | 93.6(dB) | 104.5(dB) | 103.2(dB) | +| $Q(\rho_i)=0.1(\%)$ | 3.09 | 89.5(dB) | 99.4(dB) | 98.5(dB) | +| $Q(\rho_i)=1(\%)$ | 2.33 | 84.5(dB) | 93.2(dB) | 92.9(dB) | +| $Q(\rho_i)=5(\%)$ | 1.64 | 80.0(dB) | 87.6(dB) | 87.8(dB) | +| $Q(\rho_i)=10(\%)$ | 1.28 | 77.6(dB) | 84.6(dB) | 85.1(dB) | + +**Table I.3 – Example of random sample $XT_k(i)$ with cumulative distribution point of $Q$ (%)** + +| Cumulative distribution point (%) | $\rho_i$ | $XT_k(i)$ (dB) | | | +|-----------------------------------|----------|----------------|---------------|-------------------| +| | | $k=1$ | $k=2$ | $k=3$ | +| | | Intra quad | Adjacent quad | Every second quad | +| $Q(\rho_i)=20(\%)$ | 0.842 | 74.7(dB) | 81.1(dB) | 81.9(dB) | +| $Q(\rho_i)=30(\%)$ | 0.524 | 72.6(dB) | 78.5(dB) | 79.6(dB) | +| $Q(\rho_i)=40(\%)$ | 0.253 | 70.9(dB) | 76.3(dB) | 77.6(dB) | +| $Q(\rho_i)=50(\%)$ | 0 | 69.2(dB) | 74.2(dB) | 75.7(dB) | +| $Q(\rho_i)=60(\%)$ | -0.253 | 67.5(dB) | 72.1(dB) | 73.8(dB) | +| $Q(\rho_i)=70(\%)$ | -0.524 | 65.8(dB) | 69.9(dB) | 71.8(dB) | +| $Q(\rho_i)=80(\%)$ | -0.842 | 63.7(dB) | 67.3(dB) | 69.5(dB) | +| $Q(\rho_i)=90(\%)$ | -1.28 | 60.8(dB) | 63.8(dB) | 66.3(dB) | +| $Q(\rho_i)=95(\%)$ | -1.64 | 58.4(dB) | 60.8(dB) | 63.6(dB) | +| $Q(\rho_i)=99(\%)$ | -2.33 | 53.9(dB) | 55.2(dB) | 58.5(dB) | +| $Q(\rho_i)=99.9(\%)$ | -3.09 | 48.9(dB) | 49.0(dB) | 52.9(dB) | +| $Q(\rho_i)=99.99(\%)$ | -3.72 | 44.8(dB) | 43.9(dB) | 48.2(dB) | + +### I.4.3 FEXT coupling channel transfer function + +The voltage transfer function of FEXT coupling channel is required for simulating the self-FEXT cancellation. It is given below as $HFXT_{ki}(f, d)$ , where the indices "k" and "i" show the same as $XT_k(i)$ . $\Phi_k(i)$ gives a FEXT coupling phase variation, and the value of $\Phi_k(i)$ (rad/m) is given as an arbitrary value within the range of $0-2\pi$ for each sample, which means that there can be a maximum of forty-five different values in Table I.2. + +$$HFXT_{ki}(f, d) = e^{(-\gamma d - j\phi_k(i))} 10^{-XT_k(i)/20} \left(\frac{f}{f_{FXT}}\right) \left(\frac{d}{d_{FXT}}\right)^{1/2}$$ + +where + +$f$ (Hz), + +$d$ (m): FEXT coupling length (= line length) + +$\gamma$ : line propagation constant ( $= \alpha + j\beta$ , see ITU-T G.993.1 Annex F.3) + +$XT_k(i)$ (dB): FEXT sample (at $f = f_{FXT}$ and at $d = d_{FXT}$ ) + +$\phi_k(i)$ (rad/m): a uniformly distributed random variable over the range $[0, 2\pi]$ . + +A user of this model should populate the $10 \times 10$ coupling matrix described in Table I.2 using random draws from the tri-modal distributions for the geometric dependent couplings in Table I.1. These random draw values may be assessed to their relative likelihood by comparing them with the associated values provided in Table I.3. + +# Appendix II + +## Examples of VCE control of initialization process in the activation of multiple lines in the vectored group + +(This appendix does not form an integral part of this Recommendation.) + +## II.1 Introduction + +Vectoring is designed for the FEXT cancellation across multiple VDSL2 lines. In clause 10, the initialization is described in detail mainly from the viewpoint of a single line. This appendix provides two examples of methods allowing the VCE to handle activation of multiple lines that attempt to join the vectored group in arbitrary order. If the bit "8192 superframes duration for O-P-VECTOR 1" is enabled in the ITU-T G.994.1 phase (see clause 10.2), the VCE may use the first method based on the handling lines that became late for the current initialization cycle in a waiting group. Alternatively, the VCE may use the second method based on ITU-T G.994.1 handshake capabilities to control the time when line is ready for joining. + +## II.2 VCE handling two groups of initializing lines + +In this method, the VCE maintains initializing lines in two groups after the vectored group is started. One group is called "joining group" and the other is called "waiting group". Both of the groups have two states: the open state and the closed state. When a line enters the Channel Discovery phase of the initialization, it will be added to one of the groups. Table II.1 shows the decision to which group the line is added. + +**Table II.1 – VCE decision to which group the line is added** + +| | | | | | +|------------------------------------------|----------------------------|----------------------------|--------------------------------------------------|-----------| +| Joining group state | Open | Closed | Closed | Open | +| Waiting group state | Closed | Open | Closed | Open | +| Decision by the VCE for new lines | Added to the joining group | Added to the waiting group | Will be added to the waiting group when it opens | Not valid | + +Note that the joining group and the waiting group are never in the open state at the same time. The full mechanism is described as follows: + +1. The joining group is a group of lines which are controlled by the VCE for normal initialization. These lines are currently performing or about to perform a normal initialization process after the ITU-T G.994.1 phase. Initially, after the system power is on, the joining group is open and empty. Once the VCE starts FEXT channel coefficient estimation (VTU-O starts transmission O-P-VECTOR 1 signal), the joining group is closed. The joining group can be open again when the joining process is over (no lines remain in the joining group). When a line in the joining group drops during the initialization or reaches Showtime, it is removed from the joining group. +2. The waiting group is a group of lines which are controlled by the VCE to wait prior to beginning their normal initialization after the ITU-T G.994.1 phase, until lines in the joining group complete their initialization. Initially, after the system power is on, the waiting group is closed and empty. The VCE can add new lines that have completed ITU-T G.994.1 handshake to the waiting group as follows: + - if a line is ready to join the waiting group at an instant when the waiting group is open, it joins the waiting group and the VTU-O starts transmitting on the joining line the O-P-VECTOR 1 signal with all tones active until the lines in the joining group complete the initialization. + +- if a line is ready to join the waiting group at an instant when the waiting group is closed, then the VTU-O proceeds as follows: + - if the bit "Use of O-P-VECTOR 1 flag tones only" is enabled in the ITU-T G.994.1 phase, the line joins the waiting group and the VTU-O starts transmitting on the joining line the O-P-VECTOR 1 signal with only flag tones active, while other tones are masked. When the waiting group opens, the VTU-O continues transmitting the O-P-VECTOR 1 signal now with all tones active until the lines in the joining group complete the initialization; + - if the bit "Use of O-P-VECTOR 1 flag tones only" is disabled in the ITU-T G.994.1 phase, the line waits up to 512 symbols for the waiting group to open. If the waiting group opens within 512 symbols, the VTU-O starts transmitting O-P-VECTOR 1 with all tones active until the lines in the joining group complete the initialization. Otherwise, the VTU-O returns to the state O-SILENT. + +The waiting group can only be open when the joining group is closed. When the VCE estimates the FEXT channel coefficients, the waiting group is kept closed to avoid introducing non-orthogonal crosstalk from new lines. After the estimation of FEXT channel coefficients is finished, the waiting group can be open again. If a line in the waiting group drops during the initialization, it is removed from the waiting group. + +3. When the joining lines transmit the O-P-VECTOR 1-1 and O-P-VECTOR 2-1 signals, the VCE estimates the downstream FEXT coupling coefficients from the lines of the waiting group into the lines that are in Showtime and into the lines of the joining group. Thus, the FEXT from the waiting group lines can be cancelled such that the SNR of the joining group lines can be measured with no impact of downstream FEXT from the waiting lines. +4. When the lines in the joining group are in the Channel Analysis and Exchange phase of initialization, the waiting group should be kept closed to avoid any new lines being added to the waiting group until all the joining lines have completed the SNR measurements. New lines cannot therefore disturb measuring SNR in the joining group in the Channel Analysis and Exchange phase. +5. Once there are no lines remaining in the joining group, all lines of the waiting group are moved into the joining group, and the waiting group is closed. After that, if the joining group is not empty, the VCE can start the Channel Discovery phase of the new initialization process. Otherwise, the joining group is kept open for the new activating lines thereafter. + +The above procedure is illustrated in Figure II.1. + +| ITU-T G.993.5
Initialization phases | VCE | Joining group | Waiting group | New activating lines | +|------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------|---------------|-------------------------------------------------------------------------------------------------------------------| +| Handshake | ... .. | Open | Closed | Be added to the joining group and initialize as normal | +| O-P-QUIET 1 | | | | | +| O-P-VECTOR 1 | Receive error samples to estimate downstream coefficients from joining group lines to showtime lines | Closed | | Be added to waiting group and transmits O-P-VECTOR 1 with only flag tones active | +| ... .. | ... .. | | Open | Be added to the waiting group and transmits O-P-VECTOR 1 with all tones active | +| O-P-VECTOR 1-1 | Receive error samples to update downstream coefficients from joining group lines to showtime lines | | Closed | Be added to waiting group and transmits O-P-VECTOR 1 with only flag tones active | +| ... .. | ... .. | | Open | Be added to the waiting group and transmit O-P-VECTOR 1 with all tones active | +| O-P-VECTOR 2-1 | Receive error samples to estimate downstream coefficients from showtime and joining group lines and waiting group lines to joining group lines | | Closed | Be added to waiting group and transmits O-P-VECTOR 1 with only flag tones active | +| O-P- SYNCHRO V4 | ... .. | | | | +| Channel analysis and exchange | All line SNR estimation finished | | Closed | Be blocked to add to waiting group until time out to drop | +| | | | Open | Be added to the waiting group and transmit O-P-VECTOR 1 with all tones active | +| Case 1: Showtime
Case 2: O-P-VECTOR 1 | Prepare for the next initialization procedure if there is no joining group lines or receive error samples to estimate the downstream coefficients from joining group lines to showtime lines | Case 1 : Open
Case 2: Closed | Closed | Be added to the joining group and initialize as normal or be blocked to add to both groups until time out to drop | + +G.993.5(15)\_FII.1 + +**Figure II.1 – Status of joining and waiting groups, and the new activating lines during initialization (in the case where the bit "Use of O-P-VECTOR 1 flag tones only" is enabled in the ITU-T G.994.1 phase)** + +With this controlling mechanism by the VCE, at least the following three benefits can be achieved: + +1. For the waiting group lines, they can start transmission of the O-P-VECTOR 1 signal even if they complete the ITU-T G.994.1 phase after other joining lines entered the Channel Discovery phase. Thus, the time of the ITU-T G.994.1 phase is saved. The O-P-VECTOR 1 time may be significantly shortened because VCE already estimated crosstalk from the majority of lines in the waiting group into active lines. +2. In the multiple lines initialization scenarios, the majority of lines that enter the Channel Discovery phase after the VCE starts to estimate the FEXT coupling channel coefficients will be added to the waiting group. Hence, they can start their initialization process in a synchronized step after the current initialization process handled by the VCE is completed. All lines can go to Showtime in not more than two cycles of the vectoring initialization process (from channel discovery to Channel Analysis and Exchange). Thus, initialization + +time is substantially reduced compared to the current initialization process, in which lines that arrive after the beginning of initialization are dropped back to handshake and their initialization could last for multiple cycles of the vectoring initialization process. + +3. If there are no new lines added to the waiting group after the SNR estimation during the Channel Analysis and Exchange phase, then the downstream FEXT channel coefficients from the lines of the waiting group into Showtime lines are already handled by the VCE, and the O-P-VECTOR 1 stage can be passed straight forwardly by applying the minimum O-P-VECTOR 1 duration of $4 \times 257$ symbols. This further saves initialization time. + +## II.3 VCE using handshake capabilities + +The activation of multiple lines in the vectored group may be managed by the VCE through the use of ITU-T G.994.1 handshake capabilities as follows: + +1. When new lines in the vector group enter the ITU-T G.994.1 phase of initialization, the VTU-R may continually send R-TONES-REQ to initiate handshake as defined in [ITU-T G.994.1]. +2. The VCE knows the state of all of the transceivers undergoing ITU-T G.993.5 initialization. When the VCE detects completion or near-completion of the ITU-T G.993.5 initialization cycle for the current group of joining lines, the VCE enables the VTU-Os that are detecting R-TONES-REQ to respond with C-TONES to progress with handshake for constructing the next group of joining lines. +3. The timeout of the VTU-Rs to the detection of O-SIGNATURE is vendor specific. It is observed that the duration of O-P-QUIET 1 is 1024 symbols maximum, that the duration of O-P-VECTOR 1 is $1024 \times 257$ symbols, and that the duration of O-IDLE is a maximum of 2000 symbols; this corresponds to a time period of approximately 66.5 seconds. + +# Appendix III + +## SNR-based FEXT channel estimation method + +(This appendix does not form an integral part of this Recommendation.) + +## III.1 Tools + +The SNR-based FEXT channel estimation method described in this appendix uses the reported SNR-ps (reported by the VTU-R to the VTU-O), as defined in clause 11.4.1 of [ITU T G.993.2]. + +## III.2 Estimation of FEXT channels from a new line into existing lines + +### III.2.1 Introduction + +Assuming $K$ active lines (index $i$ going from 0 to $K-1$ ) and one initializing line with number $K$ , the downstream received signal at the CPE of victim line number $i=0$ can be written as: + +$$y_0 = \underbrace{H_{0,0}x_0}_{\text{Useful signal}} + \underbrace{\sum_{i=1}^{K-1} H_{0,i}x_i}_{\text{FEXT from active lines}} + \underbrace{H_{0,K}x_K}_{\text{FEXT from new line}} + \underbrace{n_0}_{\text{External noise}} \quad (\text{III-1})$$ + +where: + +$H_{0,0}$ : The direct channel transfer function of the victim line. + +$H_{0,i}$ : For $i=1 \dots K-1$ the FEXT crosstalk channel transfer function, from active line $i$ to the victim line. + +$H_{0,K}$ : The FEXT crosstalk channel transfer function, from the new line $K$ to the victim line. + +$x_0$ : The data symbols from the victim line, with variance $\sigma_0^2$ . + +$x_i$ : For $i=1 \dots K$ , the data symbols from the active lines, with variance $\sigma_i^2$ . + +$x_K$ : The data symbols from line $K$ , with variance $\sigma_K^2$ . + +$n_0$ : The external noise on the victim line, with variance $\sigma_n^2$ . + +NOTE – In equation III-1, it is assumed that the FEXT is not yet pre-compensated. The equations applicable in the presence of pre-compensation are presented in clause III.2.7. + +The pre-coding matrix $F$ is typically defined as $H^{-1} \text{diag}(H)$ . + +If $H = \text{diag}(H)(I + C)$ is defined, then $F$ can be approximated (first order) by $F = I - \hat{C}$ , + +with $\hat{C}$ being an estimate of $C$ . + +Hence, the goal of channel estimation is to find the elements of $C$ , with + +$$C_{v,i} = \frac{H_{v,i}}{H_{v,v}}, \quad v \neq i \quad \text{so in this case, with } v = 0, \text{ this becomes } C_{0,i} = \frac{H_{0,i}}{H_{0,0}}, \text{ for } i=1 \dots K$$ + +### III.2.2 Probing signal + +Under normal conditions, the following model can be used as: + +![Figure III.1: Crosstalk model – normal condition. A diagram showing a Central Office (CO) block on the left with two output lines. The top line is labeled x_0 and the bottom line is labeled x_K. Both lines enter a yellow oval representing a cable. Inside the cable, two dashed arrows point from the input lines to two CPE blocks on the right. The top arrow is labeled H_{0,0} and the bottom arrow is labeled H_{0,K}. Below the diagram is the text 'G.993.5(15)_FIII.1'.](55f11fbbe5ef616ee7a1814f932acbaa_img.jpg) + +Figure III.1: Crosstalk model – normal condition. A diagram showing a Central Office (CO) block on the left with two output lines. The top line is labeled x\_0 and the bottom line is labeled x\_K. Both lines enter a yellow oval representing a cable. Inside the cable, two dashed arrows point from the input lines to two CPE blocks on the right. The top arrow is labeled H\_{0,0} and the bottom arrow is labeled H\_{0,K}. Below the diagram is the text 'G.993.5(15)\_FIII.1'. + +**Figure III.1 – Crosstalk model – normal condition** + +Then, a special "probing" signal can be used to estimate the crosstalk channel. + +![Figure III.2: Probing signal model – normal condition. A diagram similar to Figure III.1, but the top input line from the CO is labeled x_0 + z \cdot x_K. The bottom input line is labeled x_K. The cable and CPE blocks are the same. The dashed arrows inside the cable are labeled H_{0,0} and H_{0,K}. Below the diagram is the text 'G.993.5(15)_FIII.2'.](93bc9e79386c488b5f130ab90aacf464_img.jpg) + +Figure III.2: Probing signal model – normal condition. A diagram similar to Figure III.1, but the top input line from the CO is labeled x\_0 + z \cdot x\_K. The bottom input line is labeled x\_K. The cable and CPE blocks are the same. The dashed arrows inside the cable are labeled H\_{0,0} and H\_{0,K}. Below the diagram is the text 'G.993.5(15)\_FIII.2'. + +**Figure III.2 – Probing signal model – normal condition** + +The probing signal consists of a copy of the disturbing line, which is added to the victim. This leads to some interesting properties for the SNR. + +Define $SNR_b$ as the signal-to-noise ratio before the new line $K$ is added: + +$$SNR_b = \frac{\sigma_0^2 |H_{0,0}|^2}{\sum_{i=1}^{K-1} \sigma_i^2 |H_{0,i}|^2 + \sigma_{n0}^2} \quad (\text{III-2})$$ + +When the new line $K$ is added, and depending on the probing factor $z$ , we can define $SNR_a(z)$ as the signal-to-noise ratio after the new line $K$ is added: + +$$SNR_a(z) = \frac{\sigma_0^2 |H_{0,0}|^2}{\sum_{i=1}^{K-1} \sigma_i^2 |H_{0,i}|^2 + \sigma_K^2 |H_{0,K} + z \cdot H_{0,0}|^2 + \sigma_{n0}^2} \quad (\text{III-3})$$ + +Hence, these equations can be combined into the following equation: + +$$\frac{1}{SNR_a(z)} = \frac{\sum_{i=1}^{K-1} \sigma_i^2 |H_{0,i}|^2 + \sigma_{n0}^2 + \sigma_K^2 |H_{0,K} + z \cdot H_{0,0}|^2}{\sigma_0^2 |H_{0,0}|^2} = \frac{1}{SNR_b} + \frac{\sigma_K^2 |H_{0,K} + z \cdot H_{0,0}|^2}{\sigma_0^2 |H_{0,0}|^2} \quad (\text{III-4})$$ + +The previous step assumes the background noise and the crosstalk from the other lines ( $1..K-1$ ) to be constant during a single iteration. + +$$\left| \frac{H_{0,K}}{H_{0,0}} + z \right|^2 = \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(z)} - \frac{1}{SNR_b} \right) \quad (\text{III-5})$$ + +### III.2.3 Graphical representation + +Graphically, the effect of such probing signal on a QAM constellation point, can be represented as follows: + +![Figure III.3: Effect of probing signal on constellation point. The diagram shows a 2D coordinate system with a constellation point at (1,0). A vector labeled '1' points from the origin to this point. A vector labeled 'z' points from the origin to a point on a dashed circle of radius 1. A vector labeled 'H_{0,K}/H_{0,0}' points from the point (1,0) to another point on the dashed circle. The angle between the vector 'z' and the vector 'H_{0,K}/H_{0,0}' is labeled 'theta'. The vector 'H_{sum}/H_{0,0}' points from the origin to the point on the dashed circle. The text 'G.993.5(15)_FIII.3' is visible in the bottom right corner of the diagram area.](d83e0b0c435c17b5ce611f38d50345e7_img.jpg) + +Figure III.3: Effect of probing signal on constellation point. The diagram shows a 2D coordinate system with a constellation point at (1,0). A vector labeled '1' points from the origin to this point. A vector labeled 'z' points from the origin to a point on a dashed circle of radius 1. A vector labeled 'H\_{0,K}/H\_{0,0}' points from the point (1,0) to another point on the dashed circle. The angle between the vector 'z' and the vector 'H\_{0,K}/H\_{0,0}' is labeled 'theta'. The vector 'H\_{sum}/H\_{0,0}' points from the origin to the point on the dashed circle. The text 'G.993.5(15)\_FIII.3' is visible in the bottom right corner of the diagram area. + +**Figure III.3 – Effect of probing signal on constellation point** + +This figure assumes $\sigma_0^2 = \sigma_K^2$ , in order not to be too complicated, but the result is easily generalized (in the equations) for the case where the signal variances on the victim and disturber lines are not identical. + +Only the crosstalk of line $K$ is shown. The crosstalk from lines $1..K-1$ , is not shown, because they would make the figure too complex. + +In the figure, we can identify the following elements: + +- the decoded constellation point (the FEQ scaled it back to a unity vector of size 1); +- the probing vector $z$ , which is added as noise on the direct channel of the victim line; +- the crosstalk channel, normalized by the FEQ; +- the angle $\theta$ between the probing vector $z$ , and the normalized crosstalk channel (both are modulated with the same user data symbol $x_k$ , therefore this angle remains constant); +- the normalized total noise $\frac{H_{sum}}{H_{0,0}}$ , which rotates around the constellation point. + +### III.2.4 Derivation of the equations for crosstalk channel estimation + +In order to calculate the crosstalk channel $C_{0,K} = \frac{H_{0,K}}{H_{0,0}}$ , we can derive the following equations. + +Starting from equation III-5: + +$$\left| \frac{H_{0,K}}{H_{0,0}} + z \right|^2 = \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(z)} - \frac{1}{SNR_b} \right) \quad (\text{III-6})$$ + +when + +$z = 0$ , this leads to: + +$$\left| \frac{H_{0,K}}{H_{0,0}} \right|^2 = \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(0)} - \frac{1}{SNR_b} \right) \quad (\text{III-7})$$ + +when + +$z = \varepsilon$ , and applying trigonometry, we get: + +![Figure III.4: Detail of constellation point with z = ε. The diagram shows a vector diagram in the complex plane. A horizontal vector labeled 'z' points to the right from a starting point. From the tip of this vector, a vector labeled H_{0,K}/H_{0,0} points upwards and to the right at an angle θ relative to the horizontal dashed line. A third vector, labeled H_{sum}/H_{0,0}, is drawn from the origin to the tip of the H_{0,K}/H_{0,0} vector. The label G.993.5(19)_FIII.4 is at the bottom right.](aa4292a45b815f068c34a618c0cde0a9_img.jpg) + +Figure III.4: Detail of constellation point with z = ε. The diagram shows a vector diagram in the complex plane. A horizontal vector labeled 'z' points to the right from a starting point. From the tip of this vector, a vector labeled H\_{0,K}/H\_{0,0} points upwards and to the right at an angle θ relative to the horizontal dashed line. A third vector, labeled H\_{sum}/H\_{0,0}, is drawn from the origin to the tip of the H\_{0,K}/H\_{0,0} vector. The label G.993.5(19)\_FIII.4 is at the bottom right. + +Figure III.4 – Detail of constellation point with $z = \varepsilon$ + +$$\begin{aligned} \left| \frac{H_{0,K}}{H_{0,0}} + \varepsilon \right|^2 &= \left| \frac{H_{0,K}}{H_{0,0}} \right|^2 + \varepsilon^2 - 2 \cdot \varepsilon \cdot \left| \frac{H_{0,K}}{H_{0,0}} \right| \cos(\pi - \theta) \\ 2 \cdot \varepsilon \cdot \left| \frac{H_{0,K}}{H_{0,0}} \right| \cos(\theta) &= \left| \frac{H_{0,K}}{H_{0,0}} + \varepsilon \right|^2 - \left| \frac{H_{0,K}}{H_{0,0}} \right|^2 - \varepsilon^2 \\ 2 \cdot \varepsilon \cdot \left| \frac{H_{0,K}}{H_{0,0}} \right| \cos(\theta) &= \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(\varepsilon)} - \frac{1}{SNR_b} \right) - \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(0)} - \frac{1}{SNR_b} \right) - \varepsilon^2 \end{aligned}$$ + +when + +$z = j\varepsilon$ , we get: + +![Figure III.5: Detail of constellation point with z = jε. The diagram shows a vector diagram in the complex plane. A vertical vector labeled 'z' points upwards from a starting point. From the tip of this vector, a vector labeled H_{0,K}/H_{0,0} points upwards and to the right at an angle θ relative to the horizontal dashed line. A third vector, labeled H_{sum}/H_{0,0}, is drawn from the origin to the tip of the H_{0,K}/H_{0,0} vector. The label G.993.5(19)_FIII.5 is at the bottom.](08c5de2d22d8c666fe7f404f16d52ab5_img.jpg) + +Figure III.5: Detail of constellation point with z = jε. The diagram shows a vector diagram in the complex plane. A vertical vector labeled 'z' points upwards from a starting point. From the tip of this vector, a vector labeled H\_{0,K}/H\_{0,0} points upwards and to the right at an angle θ relative to the horizontal dashed line. A third vector, labeled H\_{sum}/H\_{0,0}, is drawn from the origin to the tip of the H\_{0,K}/H\_{0,0} vector. The label G.993.5(19)\_FIII.5 is at the bottom. + +Figure III.5 – Detail of constellation point with $z = j\varepsilon$ + +### III.2.5 Equations for crosstalk channel estimation + +Result, for $Z = \varepsilon$ + +$$\left| \frac{H_{0,K}}{H_{0,0}} \right| \cos(\theta) = \frac{1}{2\varepsilon} \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(\varepsilon)} - \frac{1}{SNR_a(0)} \right) - \frac{\varepsilon}{2} \quad (\text{III-8})$$ + +Result, for $Z = j\varepsilon$ + +$$\left| \frac{H_{0,K}}{H_{0,0}} \right| \sin(\theta) = \frac{1}{2\varepsilon} \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{SNR_a(j\varepsilon)} - \frac{1}{SNR_a(0)} \right) - \frac{\varepsilon}{2} \quad (\text{III-9})$$ + +Conclusion: + +$$\frac{H_{0,K}}{H_{0,0}} = \left| \frac{H_{0,K}}{H_{0,0}} \right| \cos(\theta) + j \cdot \left| \frac{H_{0,K}}{H_{0,0}} \right| \sin(\theta) \quad (\text{III-10})$$ + +### III.2.6 Crosstalk channel estimation algorithm + +Based on the previous equations, it can be seen that in order to calculate $C_{0,K} = \frac{H_{0,K}}{H_{0,0}}$ , we need to calculate the amplitude and phase of this quantity, which are independent parameters. + +By using equations III-8 and III-9, we have two independent equations, based on three SNR measurements, to calculate the real and imaginary parts of $C_{0,K}$ (two independent variables). + +The following measurements are required: + +- $SNR_a(0)$ the SNR after the new line $K$ has initialized, without probing signal; +- $SNR_a(\varepsilon)$ the SNR after the new line $K$ has initialized, with probing signal $\varepsilon$ ; +- $SNR_a(j\varepsilon)$ the SNR after the new line $K$ has initialized, with probing signal $j\varepsilon$ . + +Hence, the algorithm consists of the following steps: + +- 1) start transmitting a MEDLEY-type signal on the new line $K$ , with a reduced transmit PSD (No initialization); +- 2) measure $SNR_a(0)$ ; +- 3) from this value, a suitable value of $\varepsilon$ can be chosen (such that the impact on the SNR is measurable, but not excessive), and a probing signal can be added (on every victim line simultaneously); +- 4) measure $SNR_a(\varepsilon)$ ; +- 5) change the probing signal to $j\varepsilon$ ; +- 6) measure $SNR_a(j\varepsilon)$ ; +- 7) calculate $\hat{C}_{0,K}$ , for each victim line; +- 8) start the pre-coding; +- 9) increase the PSD of the MEDLEY-type signal on the new line; +- 10) repeat from 2, until the MEDLEY-type signal PSD has reached the maximum allowed PSD of this line; + +11) the normal initialization sequence on this line can now start. + +Typically, the algorithm converges in a few iterations. + +### III.2.7 Extended equations applicable while performing pre-compensation + +In case pre-coding is active, there is no fundamental change to the equations. + +The basic equation is equation III-1: + +$$y = Hx + n$$ + +$$y_0 = \underbrace{H_{0,0}x_0}_{\text{Useful signal}} + \underbrace{\sum_{i=1}^{K-1} H_{0,i}x_i}_{\text{FEXT from active lines}} + \underbrace{H_{0,K}x_K}_{\text{FEXT from new line}} + \underbrace{n_0}_{\text{External noise}}$$ + +Knowing that $H = \text{diag}(H)(I + C)$ , and when applying pre-coding, $w = Fx = (I - \hat{C})x$ , this becomes: + +$$\begin{aligned} y &= H(I - \hat{C})x \\ &= Hx - H\hat{C}x \\ &= \text{diag}(H)(I + C)x - \text{diag}(H)(I + C)\hat{C}x \\ &\approx \text{diag}(H)x + \text{diag}(H)Cx - \text{diag}(H)\hat{C}x \\ y_0 &= \underbrace{H_{0,0}x_0}_{\text{Useful signal}} + \underbrace{\sum_{i=1}^{K-1} H_{0,i}(C_{0,i} - \hat{C}_{0,i})x_i}_{\text{Residual FEXT from active lines}} + \underbrace{H_{0,K}(C_{0,K} - \hat{C}_{0,K})x_K}_{\text{Residual FEXT from line K}} + \underbrace{n_0}_{\text{External noise}} \\ &= H_{0,0}x_0 + \sum_{i=1}^{K-1} H_{0,i}|_{\text{residual}} x_i + H_{0,K}|_{\text{residual}} x_K + n_0 \end{aligned}$$ + +Consequently, we can rewrite equations III-8 and III-9 as follows: + +$$\left| \frac{H_{0,K}|_{\text{residual}}}{H_{0,0}} \right| \cos(\theta) = \frac{1}{2\varepsilon} \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{\text{SNR}_a(\varepsilon)} - \frac{1}{\text{SNR}_a(0)} \right) - \frac{\varepsilon}{2} \quad (\text{III-11})$$ + +$$\left| \frac{H_{0,K}|_{\text{residual}}}{H_{0,0}} \right| \sin(\theta) = \frac{1}{2\varepsilon} \frac{\sigma_0^2}{\sigma_K^2} \left( \frac{1}{\text{SNR}_a(j\varepsilon)} - \frac{1}{\text{SNR}_a(0)} \right) - \frac{\varepsilon}{2} \quad (\text{III-12})$$ + +Therefore, the main effect of pre-coding lies in the fact that a different value for $\varepsilon$ needs to be chosen (see also step 4, in clause III.2.6) and that in fact for the residual crosstalk channel to be estimated: + +- $\varepsilon$ needs to be such that the impact on SNR is measurable, but not excessive; +- when one knows that the residual crosstalk is estimated, the updating equation becomes trivial: + +$$\hat{C}_{0,K}(t+1) = \hat{C}_{0,K}(t) + \frac{H_{0,K}|_{residual}}{H_{0,0}} \quad (\text{III-13})$$ + +This is also illustrated graphically, as in the previous figure: + +![Figure III.6 – Detail of constellation point with pre-coding. The diagram shows a vector diagram in the complex plane. A horizontal dashed line represents the real axis, with a point 'z' marked on it. A black vector labeled \hat{C}_{0,K}(t) points from the origin to a point. A red vector labeled \frac{H_{0,K}|_{residual}}{H_{0,0}} points from the tip of the black vector to another point. A black vector labeled \hat{C}_{0,K}(t+1) points from the origin to this final point. A black vector labeled \frac{H_{sum}}{H_{0,0}} points from the origin to a point on the real axis. An angle \theta is indicated between the real axis and the red vector. The text 'G.993.5(19)_FIII.6' is at the bottom right.](b9dc3e3a1dafbc5bcd30435478addb9d_img.jpg) + +Figure III.6 – Detail of constellation point with pre-coding. The diagram shows a vector diagram in the complex plane. A horizontal dashed line represents the real axis, with a point 'z' marked on it. A black vector labeled \hat{C}\_{0,K}(t) points from the origin to a point. A red vector labeled \frac{H\_{0,K}|\_{residual}}{H\_{0,0}} points from the tip of the black vector to another point. A black vector labeled \hat{C}\_{0,K}(t+1) points from the origin to this final point. A black vector labeled \frac{H\_{sum}}{H\_{0,0}} points from the origin to a point on the real axis. An angle \theta is indicated between the real axis and the red vector. The text 'G.993.5(19)\_FIII.6' is at the bottom right. + +**Figure III.6 – Detail of constellation point with pre-coding** + +The red vector indicates the residual normalized crosstalk channel, for which a similar triangle can be constructed like before by applying a probing signal. Hence, all equations remain valid. + +## III.3 Estimation of FEXT channels from existing lines into a new line + +### III.3.1 Introduction + +Denote the number of SNR measurements used for channel estimation as $N$ . Each SNR measurement occurs over $L$ DMT symbols and all lines are in Showtime when channel estimation takes place. Consider transmission on a single tone and denote the QAM data symbol intended for line $i$ on DMT symbol $l$ during SNR measurement $n$ as $s_i^{(n)}(l)$ . The actual signal transmitted by line $i$ is denoted as $x_i^{(n)}(l)$ . + +### III.3.2 Probing signal + +When the new line $K$ initializes, the existing lines continue to transmit their data as before + +$$x_i^{(n)}(l) = s_i^{(n)}(l), \forall i < K$$ + +Channel identification is enabled by superimposing a probing signal onto the signal transmitted by the new VTU-O $K$ + +$$x_K^{(n)}(l) = s_K^{(n)}(l) + \varepsilon \sum_{i=1}^{K-1} z_i^{(n)} s_i^{(n)}(l) \quad (\text{III-14})$$ + +Note that the probing signal consists of a linear combination of the signals transmitted on the existing lines 1 to $K-1$ . A step size $\varepsilon$ is chosen such that the impact of the probing signal on the SNR is less than 3.5 dB. This is done by first measuring the SNR of line $K$ in the absence of any probing signal, which we denote $SNR_K^{(0)}$ . The step size is then set as: + +$$\varepsilon = \min_i \frac{1}{2} \frac{1}{\sqrt{SNR_K^{(0)}}} \frac{\sigma_K}{\sigma_i}$$ + +where $\sigma_i^2$ denotes the transmit power of line $i$ . Note that $z_i^{(n)}$ is chosen such that + +$$\sum_{i=1}^{K-1} |z_i^{(n)}|^2 = 1$$ + +### III.3.3 Derivation of the equations for crosstalk channel estimation + +Using equation III-14, the received signal on line $K$ is: + +$$\begin{aligned} y_K^{(n)}(l) &= \sum_{i=1}^K h_{K,i} x_i^{(n)}(l) + w_K^{(n)}(l) \\ &= h_{K,K} s_K^{(n)}(l) + \sum_{i=1}^{K-1} (h_{K,i} + \varepsilon z_i^{(n)} h_{K,K}) s_i^{(n)}(l) + w_K^{(n)}(l) \end{aligned}$$ + +The signal power on line $K$ will be measured by the VTU-R as: + +$$\begin{aligned} \text{signal}_K &= \frac{1}{L} \sum_{l=1}^L |h_{K,K} s_K^{(n)}(l)|^2 \\ &\approx |h_{K,K}|^2 \sigma_K^2 \end{aligned} \quad (\text{III-15})$$ + +The noise power on line $K$ will be measured as: + +$$\begin{aligned} \text{noise}_K &= \frac{1}{L} \sum_{l=1}^L |y_K^{(n)}(l) - h_{K,K} s_K^{(n)}(l)|^2 \\ &\approx \sum_{i=1}^{K-1} |h_{K,i} + \varepsilon z_i^{(n)} h_{K,K}|^2 \sigma_i^2 + \sigma_{W_K}^2 \end{aligned} \quad (\text{III-16})$$ + +where $\sigma_{W_K}^2$ denotes the power of the background noise. The VTU-R will then report the measured SNR to the VTU-O as: + +$$\text{SNR}_K^{(n)} = \text{signal}_K / \text{noise}_K$$ + +From equations III-15 and III-16: + +$$\begin{aligned} \frac{1}{\text{SNR}_K^{(n)}} &= \frac{\text{noise}_K}{\text{signal}_K} \\ &\approx \frac{1}{\sigma_K^2} \left( \sum_{i=1}^{K-1} \left| \frac{h_{K,i}}{h_{K,K}} \sigma_i + \varepsilon z_i^{(n)} \sigma_i \right|^2 + \frac{\sigma_{W_K}^2}{|h_{K,K}|^2} \right) \\ &= \frac{1}{\sigma_K^2} \left( \left\| \bar{\mathbf{a}} + \varepsilon \bar{\mathbf{b}}^{(n)} \right\|^2 + \frac{\sigma_{W_K}^2}{|h_{K,K}|^2} \right) \end{aligned} \quad (\text{III-17})$$ + +where we have defined $\bar{\mathbf{a}} = [\bar{a}_1 \dots \bar{a}_{K-1}]^T$ , $\bar{\mathbf{b}}^{(n)} = [\bar{b}_1^{(n)} \dots \bar{b}_{K-1}^{(n)}]^T$ with + +$$\bar{a}_i = \frac{h_{K,i}}{h_{K,K}} \sigma_i \quad (\text{III-18})$$ + +and + +$$\bar{b}_i^{(n)} = z_i^{(n)} \sigma_i \quad (\text{III-19})$$ + +Applying the general form of Pythagoras' theorem: + +$$\|\bar{\mathbf{a}} + \varepsilon \bar{\mathbf{b}}^{(n)}\|^2 = \|\bar{\mathbf{a}}\|^2 + \|\varepsilon \bar{\mathbf{b}}^{(n)}\|^2 + 2\varepsilon \operatorname{Re}\{\bar{\mathbf{b}}^{(n)H} \bar{\mathbf{a}}\} \quad (\text{III-20})$$ + +Decompose $\bar{\mathbf{a}}$ and $\bar{\mathbf{b}}^{(n)}$ into their real and imaginary components $a_{R,i} = \operatorname{Re}\{\bar{a}_i\}$ , $a_{I,i} = \operatorname{Im}\{\bar{a}_i\}$ , $b_{R,i}^{(n)} = \operatorname{Re}\{\bar{b}_i^{(n)}\}$ , and $b_{I,i}^{(n)} = \operatorname{Im}\{\bar{b}_i^{(n)}\}$ . Now: + +$$\begin{aligned} \operatorname{Re}\{\bar{\mathbf{b}}^{(n)H} \bar{\mathbf{a}}\} &= \sum_{i=1}^{K-1} a_{R,i} b_{R,i}^{(n)} + a_{I,i} b_{I,i}^{(n)} \\ &= \mathbf{b}^{(n)H} \mathbf{a}, \end{aligned}$$ + +where we define + +$$\mathbf{a} = [a_{R,1} \dots a_{R,K-1} \ a_{I,1} \dots a_{I,K-1}]^T, \quad (\text{III-21})$$ + +and $\mathbf{b}^{(n)} = [b_{R,1}^{(n)} \dots b_{R,K-1}^{(n)} \ b_{I,1}^{(n)} \dots b_{I,K-1}^{(n)}]^T$ . For convenience we also define $a_i = [\mathbf{a}]_i$ and $b_i^{(n)} = [\mathbf{b}^{(n)}]_i$ . From equation III-20: + +$$\|\bar{\mathbf{a}} + \varepsilon \bar{\mathbf{b}}^{(n)}\|^2 = \|\bar{\mathbf{a}}\|^2 + \|\varepsilon \bar{\mathbf{b}}^{(n)}\|^2 + 2\varepsilon \mathbf{b}^{(n)H} \mathbf{a}.$$ + +Now, from equation III-17: + +$$\|\bar{\mathbf{a}}\|^2 + \|\varepsilon \bar{\mathbf{b}}^{(n)}\|^2 + 2\varepsilon \mathbf{b}^{(n)H} \mathbf{a} + \frac{s_{W_K}^2}{|h_{K,K}|^2} = \frac{s_K^2}{\text{SNR}_K^{(n)}}.$$ + +Therefore + +$$\varepsilon \mathbf{b}^{(n)H} \mathbf{a} + \frac{1}{2} \|\bar{\mathbf{a}}\|^2 + \frac{1}{2} \frac{\sigma_{W_K}^2}{|h_{K,K}|^2} = \frac{1}{2} \frac{\sigma_K^2}{\text{SNR}_K^{(n)}} - \frac{1}{2} \|\varepsilon \bar{\mathbf{b}}^{(n)}\|^2.$$ + +Applying equation III-19 gives: + +$$\varepsilon \mathbf{b}^{(n)H} \mathbf{a} + \frac{1}{2} \|\bar{\mathbf{a}}\|^2 + \frac{1}{2} \frac{\sigma_{W_K}^2}{|h_{K,K}|^2} = \frac{1}{2} \frac{\sigma_K^2}{\text{SNR}_K^{(n)}} - \frac{1}{2} \varepsilon^2 \sum_{i=1}^{K-1} |z_i^{(n)}|^2 \sigma_i^2.$$ + +Define + +$$c^{(n)} = \frac{1}{2} \frac{\sigma_K^2}{\text{SNR}_K^{(n)}} - \frac{1}{2} \varepsilon^2 \sum_{i=1}^{K-1} |z_i^{(n)}|^2 \sigma_i^2. \quad (\text{III-22})$$ + +Hence + +$$\varepsilon \mathbf{b}^{(n)H} \mathbf{a} + \frac{1}{2} \|\bar{\mathbf{a}}\|^2 + \frac{1}{2} \frac{\sigma_{W_K}^2}{|h_{K,K}|^2} = c^{(n)}, \forall n. \quad (\text{III-23})$$ + +Define an $M \times N$ matrix $\mathbf{P}$ with elements $p_{m,n} = [\mathbf{P}]_{m,n}$ that satisfies + +$$\sum_{n=1}^N p_{m,n} = 0, \forall m \quad (\text{III-24})$$ + +This will be referred to as the SNR combination matrix. Now, from equation III-23: + +$$\sum_n p_{m,n} c^{(n)} = \varepsilon \sum_n p_{m,n} \mathbf{b}^{(n)H} \mathbf{a} + \left( \frac{1}{2} \|\bar{\mathbf{a}}\|^2 + \frac{1}{2} \frac{\sigma_{WK}^2}{|h_{K,K}|^2} \right) \sum_n p_{m,n}, \forall m.$$ + +Applying equation III-24, we have + +$$\sum_n p_{m,n} c^{(n)} = \varepsilon \sum_n p_{m,n} \mathbf{b}^{(n)H} \mathbf{a}, \forall m. \quad (\text{III-25})$$ + +For each $n$ , we will have one equation of the form of equation III-25. Collecting all of these equations into a matrix gives + +$$\mathbf{P} \begin{bmatrix} c^{(1)} \\ \vdots \\ c^{(N)} \end{bmatrix} = \varepsilon \mathbf{P} \begin{bmatrix} \mathbf{b}^{(1)H} \\ \vdots \\ \mathbf{b}^{(N)H} \end{bmatrix} \mathbf{a}.$$ + +Define $\mathbf{c} = [c^{(1)} \dots c^{(N)}]^T$ and the probing matrix $\mathbf{B} = [\mathbf{b}^{(1)} \dots \mathbf{b}^{(N)}]^H$ . Hence + +$$\varepsilon \mathbf{P} \mathbf{B} \mathbf{a} = \mathbf{P} \mathbf{c}$$ + +We can now find the least squares solution for $\mathbf{a}$ as + +$$\mathbf{a} = \varepsilon^{-1} \text{pinv}(\mathbf{P} \mathbf{B}) \mathbf{P} \mathbf{c}$$ + +where $\text{pinv}(\cdot)$ denotes the pseudo-inverse operation. Using equations III-18 and III-21, the normalized crosstalk coefficients can now be found as: + +$$\frac{h_{K,i}}{h_{K,K}} = \frac{1}{\sigma_i} (a_i + j a_{K-1+i}) \quad (\text{III-26})$$ + +which can be used to design the first order diagonalizing precompensator + +$$\mathbf{F} = \mathbf{I}_K - \text{offdiag} \begin{bmatrix} \frac{h_{1,1}}{h_{1,1}} & \dots & \frac{h_{1,K}}{h_{1,1}} \\ \vdots & \ddots & \vdots \\ \frac{h_{K,1}}{h_{K,K}} & \dots & \frac{h_{K,K}}{h_{K,K}} \end{bmatrix}, \quad (\text{III-27})$$ + +where we define the function $\text{offdiag}(\mathbf{X}) = \mathbf{X} - \text{diag}(\mathbf{X})$ . + +Note that in order for the set of equations to be sufficient to form an estimate of $\mathbf{a}$ , it is necessary that $\text{rank}(\mathbf{P} \mathbf{B}) \geq 2(K-1)$ . There is an additional requirement that $\sum_n p_{m,n} = 0, \forall m$ , which effectively means that the size of $\mathbf{P}$ must be at least $2(K-1) \times (2K-1)$ . Hence using this algorithm, it is possible to form an estimate of the crosstalk channels after only $2K-1$ SNR measurements. + +### III.3.4 Crosstalk channel estimation algorithm + +The channel identification algorithm operates as follows: + +- precompute $\mathbf{G} = \text{pinv}(\mathbf{PB})\mathbf{P}$ +- precompute $d^{(n)} = \sum_{i=1}^{K-1} |z_i^{(n)}|^2 \sigma_i^2 / 2, \forall n$ +- for $i = 1 \dots \text{number of iterations}$ +- transmit $x_K^{(0)}(l) = s_K^{(0)}(l)$ on line $K$ +- VTU-R reports $\text{SNR}_K^{(0)}$ +- Set step size $\varepsilon = \min_i \frac{1}{2} \frac{1}{\sqrt{\text{SNR}_K^{(0)}}} \frac{\sigma_K}{\sigma_i}$ +- for $n = 1 \dots N$ +- transmit $x_K^{(n)}(l) = s_K^{(n)}(l) + \sum_{i < K} z_i^{(n)} s_i^{(n)}(l)$ on line $K$ +- VTU-R reports $\text{SNR}_K^{(n)}$ +- calculate $c^{(n)} = \frac{1}{2} \frac{\sigma_K^2}{\text{SNR}_K^{(n)}} - \varepsilon^2 d^{(n)}$ +- end +- $\mathbf{a} = \varepsilon^{-1} \mathbf{G} \mathbf{c}$ +- $\frac{h_{K,i}}{h_{K,K}} = (a_i + j a_{K-1+i}) / \sigma_i, \forall i$ +- update crosstalk precompensator using equation III-27 +- end + +Note that in order to speed up computations, we have precomputed the pseudo-inverse $\mathbf{G}$ and the term $d^{(n)}$ . + +# Bibliography + +- [b-ITU-T G.998.1] Recommendation ITU-T G.998.1 (2005), *ATM-based multi-pair bonding*. +- [b-ITU-T G.998.2] Recommendation ITU-T G.998.2 (2005), *Ethernet-based multi-pair bonding*. +- [b-ITU-T G.998.3] Recommendation ITU-T G.998.3 (2005), *Multi-pair bonding using time-division inverse multiplexing*. +- [b-ITU-T G.9701] Recommendation ITU-T G.9701 (2019), *Fast access to subscriber terminals (G.fast) – Physical layer specification*. +- [b-ATIS-0600024] ATIS Technical Report ATIS-0600024 (2009), *Multiple-Input Multiple-Output Crosstalk Channel Model*. + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git 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lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg) + +ITU logo: A globe with a lightning bolt and the letters ITU. + +INTERNATIONAL TELECOMMUNICATION UNION + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.989.3** + +(03/2003) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Optical line +systems for local and access networks + +--- + +**Phoneline networking transceivers – Isolation +function** + +ITU-T Recommendation G.989.3 + +--- + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TESTING EQUIPMENTS | G.500–G.599 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Access networks | G.990–G.999 | +| QUALITY OF SERVICE AND PERFORMANCE | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DIGITAL TERMINAL EQUIPMENTS | G.7000–G.7999 | +| DIGITAL NETWORKS | G.8000–G.8999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# **ITU-T Recommendation G.989.3** + +## **Phoneline networking transceivers – Isolation function** + +## **Summary** + +This Recommendation specifies the characteristics and applications of an isolation function for use with phoneline networking transceiver devices in accordance with ITU-T Recs G.989.1 and G.989.2. + +The Recommendation describes how the isolation function may apply in the system reference model for in-premises phoneline networking transceivers (PNT), provides examples of usage of the isolation function, and specifies the characteristics of an isolation function which performs spectral isolation by means of a filter. + +Requirements for the implementation and deployment of G.989.3 devices are outside the scope of this Recommendation. + +### **Source** + +ITU-T Recommendation G.989.3 was prepared by ITU-T Study Group 15 (2001-2004) and approved under the ITU-T Recommendation A.8 procedure on 16 March 2003. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. + +© ITU 2003 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## CONTENTS + +| | Page | +|---------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 1 | +| 4 Abbreviations..... | 1 | +| 5 System reference model for phoneline networking transceivers..... | 2 | +| 6 Isolation function usage models ..... | 3 | +| 7 Electrical characteristics of an IF filter..... | 5 | +| 7.1 Stress withstand ..... | 5 | +| 7.2 Isolation ..... | 5 | +| 7.3 DC resistance..... | 5 | +| 7.4 Reference impedance..... | 5 | +| 7.5 Differential insertion loss ..... | 5 | +| 7.6 Common mode insertion loss ..... | 6 | +| 7.7 Differential mode return loss..... | 7 | +| 7.8 Differential mode impedance ..... | 8 | +| 7.9 Balance ..... | 8 | +| 7.10 Noise..... | 9 | +| 7.11 Group delay distortion..... | 9 | +| 7.12 Distortion..... | 9 | +| 7.13 Physical properties..... | 9 | +| Appendix I – Example of basic filter design..... | 10 | +| Appendix II – Bibliography ..... | 12 | + + + +## ITU-T Recommendation G.989.3 + +## Phoneline networking transceivers – Isolation function + +# 1 Scope + +This Recommendation specifies the characteristics and applications of an isolation function for use with phoneline networking transceiver devices in accordance with ITU-T Recs G.989.1 and G.989.2. + +Requirements for the implementation and deployment of G.989.3 devices are outside the scope of this Recommendation. + +This Recommendation does not take into account the requirements of ITU-T Rec. G.992.5 (see Bibliography [3]); this item is for further study. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation + +- ITU-T Recommendation G.989.1 (2001), *Phoneline networking transceivers – Foundation*. +- ITU-T Recommendation G.989.2 (2001), *Phoneline networking transceivers – Payload format and link layer requirements*. + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 isolation function:** A device which provides spectral isolation between the in-premises wiring and the access network, such as a filter, gateway etc. + +**3.2 station:** A G.989.1 transceiver. + +**3.3 voiceband frequencies:** Unless otherwise specified, for the purposes of this Recommendation, voiceband frequencies shall be considered as being 200 Hz to 4 kHz. + +**3.4 PNT frequencies:** Unless otherwise specified, for the purposes of this Recommendation, PNT frequencies shall be considered as being 4 MHz to 30 MHz. + +# 4 Abbreviations + +This Recommendation uses the following abbreviations: + +| | | +|------|-----------------------------------------------------------------------------------| +| ADSL | Asymmetrical Digital Subscriber Line (see ITU-T Recs G.992.1 [1] and G.992.2 [2]) | +| AN | Access Network | +| CPE | Customer Premises Equipment | +| IF | Isolation Function | +| ISDN | Integrated Services Digital Network | +| MAC | Media Access Control | + +| | | +|------|----------------------------------------------------------------------------------------------------------------------------------| +| PHY | Physical Layer | +| PNT | Phoneline Networking Transceiver | +| POTS | Plain Old Telephone Service (one of the services using the voiceband; sometimes used as a descriptor for all voiceband services) | +| PSTN | Public Switched Telephone Network | +| VDSL | Very high speed Digital Subscriber Line (see ITU-T Rec. G.993.1 [4]) | +| xDSL | a collective term referring to any of the various types of DSL technologies | + +# 5 System reference model for phoneline networking transceivers + +The system reference model for in-premises phoneline networking transceivers (PNT) is shown in Figure 1. The reference model includes physical layer (PHY) and media access control (MAC) functionality between the phoneline interface and a host interface. The primary interface is the wire-side electrical and logical interface (W1) between a PNT station and the phone wire. Typically the in-premises wiring is connected to the access network (AN). An Isolation Function (IF) separates the in-premises wiring from the access network. + +![Figure 1/G.989.3 – Basic reference model diagram showing the stack of a PNT station (MAC and PHY) connected to an in-premises phonewire via a W1 interface, with an Isolation Function (IF) separating it from the access network.](d0abac95583b52a3b35f74a215567334_img.jpg) + +The diagram illustrates the basic reference model for a PNT station. At the top, a bracket labeled 'Host-side interface' points to the connection points of the MAC layer. The MAC layer is stacked on top of the PHY layer. This stack is labeled 'PNT station (ITU-T Recs G.989.1 and G.989.2)'. Below the PHY layer is a dashed line labeled 'W1', representing the wire-side interface. Below the W1 interface is a horizontal line representing the 'In-premises phonewire'. Below the phonewire is a box labeled 'IF' (Isolation function). Below the IF box is another horizontal line representing the 'Access network'. At the bottom, the text 'G.989.3\_F01' is present. + +Figure 1/G.989.3 – Basic reference model diagram showing the stack of a PNT station (MAC and PHY) connected to an in-premises phonewire via a W1 interface, with an Isolation Function (IF) separating it from the access network. + +**Figure 1/G.989.3 – Basic reference model** + +An Isolation Function (IF) shall be implemented, when necessary, to prevent interference between PNT devices operating on in-premises wiring and access network where technologies that use an overlapping frequency spectrum e.g., VDSL, are used. + +An Isolation Function (IF) may provide: + +- spectral isolation with wide area network access technologies; +- known termination impedance; +- additional lightning and over-voltage suppression. + +Requirements for the implementation and deployment of G.989.3 devices are outside the scope of this Recommendation. + +# 6 Isolation function usage models + +The following are examples of the use of an Isolation Function. + +Figure 2 shows the simplest G.989.3 configuration. Spectral isolation between the access network and premises wiring is achieved by means of a filter, and POTS and ADSL signals pass through the filter largely unaffected. Signals above the ADSL band should be blocked. In this configuration, ADSL transceivers present in the premises may be connected to either side of the filter. VDSL transceivers that use downstream frequency bands which overlap with PNT frequencies are not expected to be connected to the in-premises side of the IF, and further, are not recommended to be connected to the access network side of the IF without additional filtering (e.g., using a splitter). + +![Figure 2/G.989.3 – Basic configuration diagram](b3baf3a29b67c7425d2562ddbc52f0cc_img.jpg) + +This diagram illustrates the basic configuration for G.989.3. On the left, the 'Access network' is connected to an 'IF filter'. The output of the 'IF filter' is connected to 'In-premises wiring'. Two 'PNT device' blocks are connected to the 'In-premises wiring'. An 'ADSL modem (optional)' is also connected to the 'In-premises wiring'. The label 'G.989.3\_F02' is at the bottom right. + +Figure 2/G.989.3 – Basic configuration diagram + +Figure 2/G.989.3 – Basic configuration + +In Figure 3, an ADSL splitter is also present. Note, in many cases, the ADSL splitter itself will isolate signals above the ADSL band at the POTS port, in effect incorporating the functionality of a G.989.3 device. + +![Figure 3/G.989.3 – Splitted configuration diagram](dbe553cf16dd14073b89a8263a428664_img.jpg) + +This diagram illustrates the splitted configuration for G.989.3. The 'Access network' is connected to a 'Splitter'. The 'Splitter' has two outputs: 'POTS' and 'xDSL'. The 'POTS' output is connected to an 'IF filter', which is then connected to 'In-premises wiring'. The 'xDSL' output is connected directly to the 'In-premises wiring'. The label 'G.989.3\_F03' is at the bottom right. + +Figure 3/G.989.3 – Splitted configuration diagram + +Figure 3/G.989.3 – Splitted configuration + +In Figure 4, a Pass-through Gateway performs the IF function. If voice service is provided in-band over xDSL and POTS service is not supported, then the IF filter is not required and the xDSL to PNT Gateway itself performs the IF function. + +![Diagram of a Gateway (Figure 4/G.989.3)](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +This diagram shows a gateway configuration. On the left, an 'Access network' line connects to a dashed box containing two stacked rectangular blocks: 'xDSL to PNT gateway' on top and 'IF filter' on the bottom. From the right side of these blocks, a line labeled 'In-premises wiring' extends to the right. The label 'G.989.3\_F04' is located at the bottom right of the diagram. + +Diagram of a Gateway (Figure 4/G.989.3) + +**Figure 4/G.989.3 – Gateway** + +In Figure 5, a gateway along with an ADSL splitter is present. As was the case in Figure 3, in many cases, the ADSL splitter itself will isolate signals above the ADSL band at the POTS port, in effect incorporating the functionality of a G.989.3 device. + +![Diagram of a Splitter plus gateway (Figure 5/G.989.3)](e6df2733626a85205c1db682e6259c46_img.jpg) + +This diagram shows a splitter and gateway configuration. An 'Access network' line on the left connects to a 'Splitter' block. The 'Splitter' has two output lines labeled 'DSL' and 'POTS'. The 'DSL' line connects to an 'xDSL to PNT gateway' block, and the 'POTS' line connects to an 'IF filter' block. Both blocks are connected to a common 'In-premises wiring' line on the right. The label 'G.989.3\_F05' is located at the bottom right of the diagram. + +Diagram of a Splitter plus gateway (Figure 5/G.989.3) + +**Figure 5/G.989.3 – Splitter plus gateway** + +Figure 6 shows an IF used with a Cable to PNT Gateway. The IF filter provides isolation between signals placed on the premises wiring by the Cable Gateway and signals on the Telephone Access Network. Optionally, if the output from the Cable Gateway contains energy in the ADSL or POTS band, then the POTS or ADSL devices (if any) would need to connect to the Telephone Access Network side of the IF. + +![Diagram of an IF in conjunction with a cable gateway (Figure 6/G.989.3)](053f1077d592e6622cd21dc4bb4cb366_img.jpg) + +This diagram shows an IF filter in conjunction with a cable gateway. A 'Cable access network' line on the left connects to a 'Cable gateway' block. A 'Telephone access network' line on the left connects to an 'IF filter' block. Both blocks are connected to a common 'In-premises wiring' line on the right. A dashed box labeled 'PSTN/ISDN devices' is connected to the 'Telephone access network' side of the 'IF filter' block via a dashed line. The label 'G.989.3\_F06' is located at the bottom right of the diagram. + +Diagram of an IF in conjunction with a cable gateway (Figure 6/G.989.3) + +**Figure 6/G.989.3 – IF in conjunction with cable gateway** + +# **7 Electrical characteristics of an IF filter** + +An Isolation Function which performs spectral isolation by means of a filter shall have the following characteristics. + +## **7.1 Stress withstand** + +The following stress conditions should be applied at the access network port of the filter. + +### **7.1.1 Voltage** + +The filter shall remain functional with the following applied: + +- 100 V dc; +- 100 V ac rms 25-50 Hz. + +### **7.1.2 Current** + +The filter shall remain functional with the following applied: + +- 100 mA max continuous. + +## **7.2 Isolation** + +### **7.2.1 Between wires** + +The isolation between wires should be greater than 5 M $\Omega$ at 100 V. + +### **7.2.2 Wire-ground** + +The isolation between wire and ground shall be greater than 100 M $\Omega$ at 100 V. + +## **7.3 DC resistance** + +The loop resistance should be less than 5 $\Omega$ . + +NOTE – In a splitterless ADSL environment, the isolation filter will be in series with the individual in-line filters used to isolate each POTS device; therefore, the total DC resistance of the filter combination must be considered. Likewise, in a splitterred ADSL environment, the use of Phoneline Networking Technology may also require the use of in-line filters to isolate POTS devices from PNT devices. In either situation, these in-line filters may be filters that allow a maximum DC resistance of 25 $\Omega$ . For example, see Bibliography [5] in Appendix II. These in-line filters will be in series with the isolation filter; therefore, to keep the total DC resistance of the residential environment under a 30-ohm limit, the DC resistance of the isolation filter must be less than 5 ohms. + +## **7.4 Reference impedance** + +The nominal reference impedance for the filter design shall be $Z_{\text{ref}}$ . $Z_{\text{ref}}$ is 100 ohms. + +## **7.5 Differential insertion loss** + +### **7.5.1 At voiceband frequencies** + +The differential insertion loss shall have the following characteristics: + +- greater than 0; +- less than 0.5 dB in the band 200 Hz-4 kHz between 600-ohm loads; +- less than 0.5 dB in the band 200 Hz-4 kHz between loads of 150 nF // 750 ohms + 270 ohms, see Figure 7. (Bibliography [6].) + +![Circuit diagram for load impedance testing. It shows a 270 ohm resistor in series with a parallel combination of a 750 ohm resistor and a 150 nF capacitor. The input and output terminals are on the left and right respectively. The label G.989.3_F07 is present in the bottom right corner.](d4af765160d04ecef538e5066006dc77_img.jpg) + +Circuit diagram for load impedance testing. It shows a 270 ohm resistor in series with a parallel combination of a 750 ohm resistor and a 150 nF capacitor. The input and output terminals are on the left and right respectively. The label G.989.3\_F07 is present in the bottom right corner. + +**Figure 7/G.989.3 – Load impedance for insertion loss testing** + +### 7.5.2 Above voiceband up to 1104 kHz + +The differential insertion loss shall have the following characteristics: + +- greater than 0; +- less than 0.5 dB in the band 4 kHz-552 kHz between $Z_{\text{ref}}$ -ohm loads; +- less than an amount increasing linearly with the logarithm of frequency from 0.5 dB at 552 kHz and 1 dB at 1104 kHz, as shown in Figure 8. + +![Graph of Insertion loss [dB] versus Frequency [Hz] on a logarithmic scale. The y-axis ranges from -1.5 to 1. The x-axis ranges from 10,000 to 1,000,000 Hz. A red line shows the insertion loss: it is 0 dB from 10,000 Hz to 552,000 Hz, then decreases linearly to -1.0 dB at 1,104,000 Hz, and then drops vertically to -1.5 dB.](602ada2a012ff3cc38d91de2eec5b450_img.jpg) + +Graph of Insertion loss [dB] versus Frequency [Hz] on a logarithmic scale. The y-axis ranges from -1.5 to 1. The x-axis ranges from 10,000 to 1,000,000 Hz. A red line shows the insertion loss: it is 0 dB from 10,000 Hz to 552,000 Hz, then decreases linearly to -1.0 dB at 1,104,000 Hz, and then drops vertically to -1.5 dB. + +**Figure 8/G.989.3 – Differential insertion loss** + +### 7.5.3 At PNT frequencies + +The differential insertion loss shall be greater than 35 dB in the band 4-5.1 MHz, 41 dB in the band 5.1-8.5 MHz, 35 dB in the band 8.5-30 MHz, between $Z_{\text{ref}}$ -ohm loads. + +## 7.6 Common mode insertion loss + +### 7.6.1 At PNT frequencies + +The common mode insertion loss shall be greater than 20 dB in the band 4-30 MHz between 50-ohm loads, as shown in Figure 9. + +![Figure 9/G.989.3 – Common mode insertion loss measurement. The diagram shows a circuit with an AC voltage source ~Vs connected in series with a 50 ohm resistor to the 'Access network' port of a 'DUT'. The 'In-premises wiring' port of the 'DUT' is connected to a 50 ohm resistor, with the output voltage Vo measured across it. The formula for common mode insertion loss is IL_CM = 20 log10 (Vs/Vo/2). The diagram is labeled G.989.3_F09.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +$IL_{CM} = 20 \log_{10} (Vs/Vo/2)$ + +G.989.3\_F09 + +Figure 9/G.989.3 – Common mode insertion loss measurement. The diagram shows a circuit with an AC voltage source ~Vs connected in series with a 50 ohm resistor to the 'Access network' port of a 'DUT'. The 'In-premises wiring' port of the 'DUT' is connected to a 50 ohm resistor, with the output voltage Vo measured across it. The formula for common mode insertion loss is IL\_CM = 20 log10 (Vs/Vo/2). The diagram is labeled G.989.3\_F09. + +**Figure 9/G.989.3 – Common mode insertion loss measurement** + +## 7.7 Differential mode return loss + +Differential mode return loss requirements applies to both ports of the filter, see Figure 10. + +![Figure 10/G.989.3 – Differential mode return loss measurements. The diagram consists of two parts. The top part shows the 'DUT' with 'Access network' and 'In-premises wiring' ports. A 'Measured impedance, Zx' is indicated at the 'Access network' port, and a 'Test impedance, Zo' is connected to the 'In-premises wiring' port. The formula for return loss is RL = 20 log10 (|Zx+Zo|/|Zx-Zo|). The bottom part shows the same 'DUT' with 'Test impedance, Zo' connected to the 'Access network' port and 'Measured impedance, Zx' indicated at the 'In-premises wiring' port. The same formula for return loss is shown. The diagram is labeled G.989.3_F10.](cab0834804fb031b43865554cc8d06ab_img.jpg) + +$RL = 20 \log_{10} (|Zx+Zo|/|Zx-Zo|)$ + +G.989.3\_F10 + +Figure 10/G.989.3 – Differential mode return loss measurements. The diagram consists of two parts. The top part shows the 'DUT' with 'Access network' and 'In-premises wiring' ports. A 'Measured impedance, Zx' is indicated at the 'Access network' port, and a 'Test impedance, Zo' is connected to the 'In-premises wiring' port. The formula for return loss is RL = 20 log10 (|Zx+Zo|/|Zx-Zo|). The bottom part shows the same 'DUT' with 'Test impedance, Zo' connected to the 'Access network' port and 'Measured impedance, Zx' indicated at the 'In-premises wiring' port. The same formula for return loss is shown. The diagram is labeled G.989.3\_F10. + +**Figure 10/G.989.3 – Differential mode return loss measurements** + +### 7.7.1 At POTS frequencies + +The differential mode return loss shall have the following characteristics: + +- greater than 18 dB in the band 200 Hz-4 kHz between 600-ohm loads; +- greater than 18 dB in the band 200 Hz-4 kHz between loads of 150 nF // 750 ohms + 270 ohms (Bibliography [6]). + +### 7.7.2 Above voiceband up to 1104 kHz + +The differential mode return loss shall have the following characteristics: + +- greater than 18 dB in the band 10 kHz-552 kHz between $Z_{\text{ref}}$ -ohm loads; +- greater than 6 dB at 1104 kHz between $Z_{\text{ref}}$ -ohm loads; +- as shown in Figure 11. + +![Figure 11/G.989.3 – Differential mode return loss graph](0332672e127cd13bb6d2fc8d1e27bfa2_img.jpg) + +A line graph showing the differential mode return loss in dB versus frequency in Hz. The y-axis is labeled 'Return loss [dB]' and ranges from 0 to 30 in increments of 5. The x-axis is labeled 'Frequency [Hz]' and has major ticks at 10 000, 20 000, 50 000, 100 000, 200 000, 500 000, and 1 × 106. A red line represents the return loss, which starts at 10 000 Hz at approximately 18 dB, remains constant until 552 000 Hz, then decreases linearly to about 6 dB at 1 104 000 Hz, and finally drops sharply to 0 dB at 1 104 000 Hz. + +| Frequency [Hz] | Return loss [dB] | +|----------------|------------------| +| 10 000 | 18 | +| 552 000 | 18 | +| 1 104 000 | 6 | +| 1 104 000 | 0 | + +G.989.3\_F11 + +Figure 11/G.989.3 – Differential mode return loss graph + +Figure 11/G.989.3 – Differential mode return loss + +## 7.8 Differential mode impedance + +### 7.8.1 At PNT frequencies + +The differential mode impedance at the in premises wiring side of the IF shall be greater than 160 ohms in the band 4 MHz-30 MHz. + +## 7.9 Balance + +### 7.9.1 At voiceband frequencies + +The filter shall have the following balance characteristics: + +- greater than 40 dB in the band 15-50 Hz when terminated with 600 ohms; +- greater than 46 dB in the band 50-600 Hz when terminated with 600 ohms; +- greater than 52 dB in the band 600-3400 Hz when terminated with 600 ohms. + +### 7.9.2 Above voiceband up to 1104 kHz + +At the access side, the filter shall have the following balance characteristics: + +- greater than 46 dB in the band 10-552 kHz when terminated with $Z_{\text{ref}}$ -ohm centre tap grounded at the in premises wiring side; +- greater than 40 dB in the band 552-1104 kHz when terminated with $Z_{\text{ref}}$ -ohm centre tap grounded at the in premises wiring side. + +### **7.9.3 At PNT frequencies** + +At the line side, the filter shall have the following balance characteristics: + +- greater than 35 dB in the band 4-30 MHz when terminated with $Z_{\text{ref}}$ -ohm differential, and 100 ohms from one leg to ground at in premises wiring side. (i.e., deliberately unbalanced load). + +## **7.10 Noise** + +Noise levels shall be measured at the AN port of the filter. + +### **7.10.1 At POTS frequencies** + +Noise levels shall be less than $-80$ dBVp total into 600 ohms in the band 200 Hz-3.4 kHz. + +### **7.10.2 Between voiceband and PNT frequencies** + +Noise levels shall be less than $-80$ dBm total into $Z_{\text{ref}}$ ohms in the band 10 kHz-1104 kHz. + +### **7.10.3 At PNT frequencies** + +Noise levels shall be less than $-66$ dBm total into $Z_{\text{ref}}$ ohms in the band 4 MHz-30 MHz. + +## **7.11 Group delay distortion** + +### **7.11.1 Between voiceband and PNT frequencies** + +For further study. + +## **7.12 Distortion** + +### **7.12.1 Between voiceband and PNT frequencies** + +With a wideband test signal covering the band 160 kHz-1104 kHz with of level $+20$ dBm, and a power spectral density of $-40$ dBm/Hz, applied from a $Z_{\text{ref}}$ -ohm source at the line side of the filter, the total noise and intermodulation measured in the band 25 kHz to 138 kHz in a 100-ohm load on the in premises wiring side shall not exceed $-140$ dBm/Hz. + +With a wideband test signal covering the band 25 kHz-138 kHz with of level $+12.5$ dBm, and a power spectral density of $-38$ dBm/Hz, applied from a $Z_{\text{ref}}$ -ohm source at the in premises wiring side of the filter, the total noise and intermodulation measured in the band 160 kHz to 1104 kHz in a 100-ohm load at the line side shall not exceed $-140$ dBm/Hz. + +## **7.13 Physical properties** + +Physical properties of the filter are not defined in this Recommendation. + +# Appendix I + +## Example of basic filter design + +A schematic of a filter which could meet the requirements of clause 7, where $Z_{\text{ref}}$ is 100 ohms, is shown in Figure I.1 below. + +![Schematic diagram of a filter (Figure I.1/G.989.3). The circuit is a balanced filter. On the 'In premises wiring side', there are two 15.5 μH inductors, one on each line. Between these lines is a shunt branch consisting of a 0.68 μH inductor in series with a 1.9 nF capacitor. Following this, there is a common-mode choke labeled '100 μH common-mode with 15.5 μH leakage; fo ~7 MHz'. The output leads to the 'Access network side'.](1a827b10290f33d4fec04d0e8ef7a897_img.jpg) + +Schematic diagram of a filter (Figure I.1/G.989.3). The circuit is a balanced filter. On the 'In premises wiring side', there are two 15.5 μH inductors, one on each line. Between these lines is a shunt branch consisting of a 0.68 μH inductor in series with a 1.9 nF capacitor. Following this, there is a common-mode choke labeled '100 μH common-mode with 15.5 μH leakage; fo ~7 MHz'. The output leads to the 'Access network side'. + +Figure I.1/G.989.3 – Example filter schematic + +For example, the 100-ohm differential insertion loss would be as shown in Figure I.2. + +![Graph of Insertion loss [dB] versus Frequency [Hz] (Figure I.2/G.989.3). The y-axis ranges from -1.5 to 1 dB in increments of 0.5. The x-axis is logarithmic, showing values 10,000, 20,000, 50,000, 100,000, 200,000, 500,000, and 1,000,000 Hz. A black curve shows the insertion loss staying near 0 dB until ~700 kHz, then dropping sharply. A red line shows a mask: 0 dB from 10 kHz to 1 MHz, and a lower limit at -0.5 dB from 10 kHz to 500 kHz, then sloping down to -1.0 dB at 1 MHz.](011fecb4a85637472f0c697a6cbdb15d_img.jpg) + +| Frequency [Hz] | Insertion Loss [dB] (Actual) | Lower Mask Limit [dB] | +|----------------|------------------------------|-----------------------| +| 10,000 | ~ -0.05 | -0.5 | +| 100,000 | ~ -0.05 | -0.5 | +| 500,000 | ~ -0.1 | -0.5 | +| 800,000 | ~ -0.2 | ~ -0.8 | +| 1,000,000 | ~ -1.6 | -1.0 | + +Graph of Insertion loss [dB] versus Frequency [Hz] (Figure I.2/G.989.3). The y-axis ranges from -1.5 to 1 dB in increments of 0.5. The x-axis is logarithmic, showing values 10,000, 20,000, 50,000, 100,000, 200,000, 500,000, and 1,000,000 Hz. A black curve shows the insertion loss staying near 0 dB until ~700 kHz, then dropping sharply. A red line shows a mask: 0 dB from 10 kHz to 1 MHz, and a lower limit at -0.5 dB from 10 kHz to 500 kHz, then sloping down to -1.0 dB at 1 MHz. + +Figure I.2/G.989.3 – Example filter differential insertion loss + +The stop-band attenuation would be as shown in Figure I.3. + +![Figure I.3/G.989.3 – Example filter stop-band attenuation. A graph showing Attenuation [dB] on the y-axis (from -40 to 10) versus Frequency [10^6 Hz] on the x-axis (logarithmic scale from 1x10^6 to 1.5x10^7). A black curve shows a smooth transition from 0 dB to -40 dB. A red line shows a sharp drop to -35 dB, a step to -40 dB, and a return to -35 dB at higher frequencies.](af06598cfb31b517e79b50d74f72a0ca_img.jpg) + +This graph illustrates the stop-band attenuation for a filter. The y-axis represents Attenuation in dB, ranging from -40 to 10. The x-axis represents Frequency in units of $10^6$ Hz, with a logarithmic scale from $1 \times 10^6$ to $1.5 \times 10^7$ . A black curve shows a smooth, gradual increase in attenuation starting from 0 dB at low frequencies, reaching -40 dB at approximately $4 \times 10^6$ Hz, and then slightly rising to about -35 dB at $10^7$ Hz. A red line shows a sharp drop in attenuation at approximately $4 \times 10^6$ Hz, reaching -35 dB, then stepping down to -40 dB at $5 \times 10^6$ Hz, and finally stepping back up to -35 dB at $8 \times 10^6$ Hz. + +Figure I.3/G.989.3 – Example filter stop-band attenuation. A graph showing Attenuation [dB] on the y-axis (from -40 to 10) versus Frequency [10^6 Hz] on the x-axis (logarithmic scale from 1x10^6 to 1.5x10^7). A black curve shows a smooth transition from 0 dB to -40 dB. A red line shows a sharp drop to -35 dB, a step to -40 dB, and a return to -35 dB at higher frequencies. + +**Figure I.3/G.989.3 – Example filter stop-band attenuation** + +The 100-ohm return loss (at either port) would be as shown in Figure I.4. + +![Figure I.4/G.989.3 – Example filter return loss. A graph showing Return loss [dB] on the y-axis (from 5 to 30) versus Frequency [Hz] on the x-axis (logarithmic scale from 10 000 to 1 x 10^6). A black curve shows a sharp peak at 1 x 10^6 Hz. A red line shows a flat return loss of 18 dB from 10 000 Hz to 500 000 Hz, then a drop to 5 dB at 1 x 10^6 Hz.](fdcfba1180dc160c7d539c5fb2a6c1e6_img.jpg) + +This graph illustrates the 100-ohm return loss for a filter. The y-axis represents Return loss in dB, ranging from 5 to 30. The x-axis represents Frequency in Hz, with a logarithmic scale from 10 000 to $1 \times 10^6$ . A black curve shows a sharp peak in return loss at $1 \times 10^6$ Hz, reaching a value of 30 dB. A red line shows a flat return loss of 18 dB from 10 000 Hz to 500 000 Hz, then a drop to 5 dB at $1 \times 10^6$ Hz. + +Figure I.4/G.989.3 – Example filter return loss. A graph showing Return loss [dB] on the y-axis (from 5 to 30) versus Frequency [Hz] on the x-axis (logarithmic scale from 10 000 to 1 x 10^6). A black curve shows a sharp peak at 1 x 10^6 Hz. A red line shows a flat return loss of 18 dB from 10 000 Hz to 500 000 Hz, then a drop to 5 dB at 1 x 10^6 Hz. + +**Figure I.4/G.989.3 – Example filter return loss** + +# Appendix II + +## Bibliography + +The following references are intended for background information (i.e., they are informative not normative). + +- [1] ITU-T Recommendation G.992.1 (1999), *Asymmetrical digital subscriber line (ADSL) transceivers.* +- [2] ITU-T Recommendation G.992.2 (1999), *Splitterless asymmetric digital subscriber line (ADSL) transceivers.* +- [3] ITU-T Recommendation G.992.5 (2003), *Asymmetric Digital Subscriber Line (ADSL) Transceivers – Extended Bandwidth ADSL2 (ADSL2+).* +- [4] ITU-T Recommendation G.993.1 (2001), *Very high speed digital subscriber line foundation.* +- [5] Committee T1 T1.421-2001, *In-line Filter for Use with Voiceband Terminal Equipment Operating on the Same Wire Pair with High Frequency (up to 12 MHz) Devices.* +- [6] ETSI TBR 021, *Terminal Equipment (TE); Attachment requirements for pan-European approval for connection to the analogue Public Switched Telephone Networks (PSTNs) of TE (excluding TE supporting the voice telephony service) in which network addressing, if provided, is by means of Dual Tone Multi Frequency (DTMF) signalling.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|--------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series B | Means of expression: definitions, symbols, classification | +| Series C | General telecommunication statistics | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks and open system communications | +| Series Y | Global information infrastructure and Internet protocol aspects | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9963-202306-I_PDF-E/raw.md b/marked/G/T-REC-G.9963-202306-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..74f7ba7e628c8d221e49ba7add1956bea76fbf5f --- /dev/null +++ b/marked/G/T-REC-G.9963-202306-I_PDF-E/raw.md @@ -0,0 +1,3312 @@ + + +# Recommendation **ITU-T G.9963 (06/2023)** + +SERIES G: Transmission systems and media, digital +systems and networks + +Access networks – In premises networks + +--- + +## **Unified high-speed wireline-based home networking transceivers – Multiple input/multiple output specification** + +![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg) + +The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with white lines representing latitude and longitude, and the letters 'ITU' in a bold, blue, sans-serif font superimposed on the globe. + +ITU logo + +## ITU-T G-SERIES RECOMMENDATIONS **Transmission systems and media, digital systems and networks** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100-G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200-G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300-G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400-G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450-G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600-G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700-G.799 | +| DIGITAL NETWORKS | G.800-G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900-G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000-G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000-G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000-G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000-G.8999 | +| ACCESS NETWORKS | G.9000-G.9999 | +| Metallic access networks | G.9700-G.9799 | +| Optical line systems for local and access networks | G.9800-G.9899 | +| In premises networks | G.9900-G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +# Recommendation ITU-T G.9963 + +## Unified high-speed wireline-based home networking transceivers – Multiple input/multiple output specification + +## Summary + +Recommendation ITU-T G.9963 belongs to the family of ITU-T G.996x Recommendations. Recommendation ITU-T G.9963 specifies the additions and modifications to Recommendations ITU-T G.9960 and ITU-T G.9961 that are needed for a multiple input multiple output (MIMO) home networking transceiver capable of operating over premises power-line wiring. MIMO transceivers are able to transmit and receive over three power-line conductors (phase, neutral and ground). This Recommendation also specifies the means by which transceivers that comply with ITU-T G.9960, ITU-T G.9961 and ITU-T G.9963 interoperate when used on the same wires. + +## History \* + +| Edition | Recommendation | Approval | Study Group | Unique ID | +|---------|----------------------------|------------|-------------|--------------------| +| 1.0 | ITU-T G.9963 | 2011-12-16 | 15 | 11.1002/1000/11404 | +| 1.1 | ITU-T G.9963 (2011) Amd. 1 | 2014-01-13 | 15 | 11.1002/1000/12083 | +| 1.2 | ITU-T G.9963 (2011) Cor. 1 | 2014-04-04 | 15 | 11.1002/1000/12082 | +| 2.0 | ITU-T G.9963 | 2015-07-03 | 15 | 11.1002/1000/12402 | +| 2.1 | ITU-T G.9963 (2015) Cor. 1 | 2016-04-13 | 15 | 11.1002/1000/12819 | +| 2.2 | ITU-T G.9963 (2015) Amd. 1 | 2016-07-22 | 15 | 11.1002/1000/12820 | +| 3.0 | ITU-T G.9963 | 2018-11-29 | 15 | 11.1002/1000/13778 | +| 3.1 | ITU-T G.9963 (2018) Amd. 1 | 2021-04-23 | 15 | 11.1002/1000/14533 | +| 4.0 | ITU-T G.9963 | 2023-06-13 | 15 | 11.1002/1000/15557 | + +## Keywords + +Architecture, DLL layer, G.hn, MIMO, phoneline, PHY layer, powerline. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at . + +© ITU 2023 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|-------------------------------------------------------------------------------------------------|----| +| 1 | Scope ..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 2 | +| 3.1 | Terms defined elsewhere ..... | 2 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Home network architecture and reference models ..... | 4 | +| 6 | Profiles..... | 4 | +| 7 | Physical layer specification (PHY layer)..... | 4 | +| 7.1 | Medium independent specification..... | 4 | +| 7.2 | Medium dependent specification..... | 49 | +| 8 | Data link layer specification of the MIMO transceiver ..... | 49 | +| 8.1 | Functional model and frame formats..... | 49 | +| 8.2 | MAP controlled medium access..... | 49 | +| 8.3 | Transmission opportunities (TXOPs) and time slots (TSs)..... | 49 | +| 8.4 | Control parameters for APC, LLC and MAC ..... | 50 | +| 8.5 | Functions of the endpoint node ..... | 50 | +| 8.6 | Domain master node functional capabilities ..... | 50 | +| 8.7 | Addressing scheme..... | 51 | +| 8.8 | Medium access plan (MAP) frame..... | 51 | +| 8.9 | Retransmission and acknowledgement protocol ..... | 52 | +| 8.10 | Management and control message format..... | 52 | +| 8.11 | Channel estimation protocol..... | 54 | +| 8.12 | Connection management ..... | 85 | +| 8.13 | Message flooding..... | 85 | +| 8.14 | Operation in the presence of neighbouring domains – Distributed domain coordination (NDIM)..... | 85 | +| 8.15 | Coexistence with alien power-line networks..... | 85 | +| 8.16 | PHY multicast binding protocol..... | 85 | +| 8.17 | DLL multicast stream ..... | 86 | +| 8.18 | Inter-OFB interoperability..... | 86 | +| 8.19 | Node information and capabilities exchange ..... | 86 | +| 8.20 | Metrics acquisition ..... | 86 | +| 8.21 | Operation in power saving modes ..... | 86 | +| 8.22 | Layer 2 configuration and management protocol (LCMP) ..... | 86 | +| 8.23 | MIMO transmission..... | 86 | +| 8.24 | Run-length compression of fields of management messages..... | 88 | +| 8.25 | Payload compression in management messages ..... | 88 | + +| | Page | +|-------------------------------------------------------------------------------------|------| +| 8.26 TLV pool ..... | 88 | +| 9 Security ..... | 88 | +| Annex A – Regional requirements for North America ..... | 89 | +| Annex B ..... | 89 | +| Annex C – Regional requirements for Japan ..... | 89 | +| Annex D – International amateur radio bands ..... | 89 | +| Annex E – Impact of ITU-T G.9960 on VDSL2 service ..... | 89 | +| Annex F ..... | 90 | +| Annex G – Test vectors ..... | 90 | +| Annex H – Application protocol convergence sublayer ..... | 90 | +| Annex I – Interoperability between Profile 1 and Profile 2 OFB transmissions ..... | 90 | +| Annex J – IEEE 802.1X port-based network access control ..... | 90 | +| Annex K to Annex Q ..... | 91 | +| Annex R – Use of reverse power feeding techniques for G.hn over coaxial media ..... | 91 | +| Annex S to Annex W ..... | 91 | +| Annex X – Test vectors ..... | 91 | + +# Recommendation ITU-T G.9963 + +## Unified high-speed wireline-based home networking transceivers – Multiple input/multiple output specification + +# 1 Scope + +This Recommendation describes the modifications to [ITU-T G.9960] and [ITU-T G.9961] that are needed to define MIMO home networking transceivers for operation over power-line or telephone wiring. More specifically, this Recommendation includes the following: + +- the PHY functional models of the MIMO transceivers; +- detailed descriptions of the modifications (changes and additions) needed in the PHY and DLL sections relative to [ITU-T G.9960] and [ITU-T G.9961]; +- the means by which transceivers that comply with [ITU-T G.9960], [ITU-T G.9961] and this Recommendation interoperate when operating on the same wires; and +- the means by which transmissions from ITU-T G.9963 transceivers do not degrade the performance of transceivers that comply with [ITU-T G.9960] and [ITU-T G.9961] when operating on the same wires. + +An ITU-T G.9963 transceiver shall be fully compliant with [ITU-T G.9960] and [ITU-T G.9961]. + +NOTE – In those regions, or particular installations, where only two conductors are used for mains sockets in the case of powerline or a single pair of wires is used in the case of telephone cable, a modem equipped with a MIMO transceiver will behave as an [ITU-T G.9960] transceiver. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.9960] Recommendation ITU-T G.9960 (2019), *Unified high-speed wireline-based home networking transceivers – System architecture and physical layer specification*. +- [ITU-T G.9961] Recommendation ITU-T G.9961 (2018), *Unified high-speed wireline-based home networking transceivers – Data link layer specification*. +- [ITU-T G.9962] Recommendation ITU-T G.9962 (2018), *Unified high-speed wireline-based home networking transceivers – Management specification*. +- [ITU-T G.9964] Recommendation ITU-T G.9964 (2011), *Unified high-speed wireline-based home networking transceivers – Power spectral density specification*. +- [ITU-T G.9991] Recommendation ITU-T G.9991 (2019), *High-speed indoor visible light communication transceiver – System architecture, physical layer and data link layer specification*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +Unless otherwise noted, the definitions in [ITU-T G.9960] and [ITU-T G.9961] shall apply. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 ground conductor (G):** A conductor in an electrical branch circuit that does not carry mains current under normal operation. It provides a low-impedance return path for ground-fault current back to the service entrance panel for the purposes of protecting personnel and equipment and ensuring circuit breaker trip. At the service entrance panel, this conductor is bonded to an earthing (grounding) electrode. In regulations in some regions this is commonly referred to as the equipment grounding conductor (EGC). + +NOTE 1 – Some electrical appliances do not connect to the ground conductor. + +NOTE 2 – The neutral and ground conductors are commonly bonded together in the service entrance panel and nowhere else, by virtue of their common bonding to the earthing electrode. + +**3.2.2 MIMO channel:** A channel that has multiple input ports (Tx ports) and multiple output ports (Rx ports). A "2 X 2" MIMO channel has 2 Tx ports and 2 Rx ports. + +**3.2.3 MIMO transmission:** Transmission where one or two spatial streams are converted into two transmit streams. + +**3.2.4 neutral conductor (N):** A conductor in an electrical branch circuit that serves as the reference conductor and return path for current supplied by the circuit's phase conductor(s). At the service entrance panel, this conductor may be bonded to an earthing (ground) electrode. In such cases, regulations in some regions refer to it as the "grounded conductor". + +NOTE – Not all branch circuits include a neutral conductor. The term "grounded conductor" should not be confused with the term "ground conductor" or EGC. + +**3.2.5 phase conductor (P):** A conductor in an electrical branch circuit that is energized with mains' voltage with respect to the circuit's reference conductor. In regulations in some regions, this is commonly referred to as a "line conductor". + +**3.2.6 spatial stream:** A stream of data that may be mapped for transmission over one or more ports. + +**3.2.7 transmit stream:** A stream of symbols created by the Tx port mapper. Each transmit stream is assigned for transmission over a specific Tx port. + +**3.2.8 Tx (or Rx) port:** In powerline, a physical connection to the power-line medium using a combination of the available three conductors (phase (P), neutral (N), and ground (G)) for transmitting and receiving signals. An example of a port is a pair of conductors, such as P-N, N-G or P-G. In a telephone cable, a physical connection to a pair of conductors. A port used for transmission is called a "Tx port". A port used for reception is called an "Rx port". + +**3.2.9 Tx port mapper:** A function that maps pairs of constellation points assigned to the two spatial streams on the same sub-carrier, to a modified pair of signals that (after orthogonal frequency division multiplexing (OFDM) modulation, i.e., inverse discrete Fourier transform (IDFT) are connected to Tx ports. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|-----|-------------------------------| +| ACE | Additional Channel Estimation | +|-----|-------------------------------| + +| | | +|------|--------------------------------------------| +| APC | Application Protocol Convergence | +| BAT | Bit Allocation Table | +| BMAT | Bit and Tx port Mapping Allocation Table | +| DLL | Data Link Layer | +| DOD | Domain identifier | +| DSL | Digital Subscriber Line | +| EGC | Equipment Grounding Conductor | +| FEC | Forward Error Correction | +| IDFT | Inverse Discrete Fourier Transform | +| IDPS | Inter-Domain Presence Signal | +| ISC | Inactive Sub-Carrier | +| LFSR | Linear Feedback Shift Register | +| LSB | Least Significant Bit | +| MAC | Medium Access Control | +| MAP | Medium Access Plan | +| MAT | Mapping Allocation Table | +| MDI | Medium-Dependent Interface | +| MIMO | Multiple Input/Multiple Output | +| MPDU | Media access control Protocol Data Unit | +| MSC | Masked Sub-Carrier | +| OFB | Operational Frequency Band | +| OFDM | Orthogonal Frequency Division Multiplexing | +| PCS | Physical Coding Sub-layer | +| PG | Precoding Grouping | +| PHY | Physical layer | +| PMA | Physical Medium Attachment | +| PMD | Physical Medium Dependent | +| PMI | Physical Medium-independent Interface | +| PMSC | Permanently Masked Sub-Carrier | +| PR | Priority Resolution | +| PSD | Power Spectral Density | +| QoS | Quality of Service | +| RMAP | Relayed Medium Access Plan | +| RMSC | Regionally Masked Sub-Carrier | +| SM | Sub-carrier Mark | +| SS | Spatial Stream | +| SSC | Supported Sub-Carrier | + +| | | +|------|--------------------------| +| TPM | Tx Port Mapping | +| TS | Time Slot | +| TXOP | Transmission Opportunity | + +# 5 Home network architecture and reference models + +See clause 5 of [ITU-T G.9960]. + +# 6 Profiles + +See clause 6 of [ITU-T G.9960]. + +# 7 Physical layer specification (PHY layer) + +## 7.1 Medium independent specification + +### 7.1.1 Functional model of the PHY + +As stated in clause 1, an ITU-T G.9963 compliant transceiver (i.e., a MIMO transceiver) shall be fully compliant with [ITU-T G.9960] and [ITU-T G.9961]. As such, a MIMO transceiver is able to operate based upon the functional models described in clause 7.1.1 (general PHY model), clause 7.1.2 (PCS), clause 7.1.3 (PMA) and clause 7.1.4 (PMD) of [ITU-T G.9960]. Such an operation, resulting in ITU-T G.9960 transmission, may be used for certain transmission cases, as described in clause 7.1.2.1. + +The functional model of the PHY layer of a MIMO transceiver, for cases of MIMO transmission, is presented in Figure 7-1. The physical medium-independent interface (PMI) and the medium-dependent interface MDI are, respectively, two demarcation reference points between the PHY and the medium access control (MAC), and between the PHY and transmission medium. Internal reference points $\delta$ and $\alpha$ show separation between the physical medium dependent (PMD) and physical medium attachment (PMA), and between the physical coding sub-layer (PCS) and PMA, respectively. + +![Figure 7-1 – PHY functional model of the MIMO transceiver. The diagram shows the flow of data from the MAC (PMI) through the Physical coding (PCS), Physical media attachment (PMA), and Physical medium dependent (PMD) sublayers to the Transmission medium (MDI). It also shows the receive path and control signals from PHY management.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +The diagram illustrates the PHY functional model of a MIMO transceiver, showing the flow of data and control signals between the MAC and the Transmission medium (MDI). + +- PMI (Physical Medium Interface):** The interface between the MAC and the PCS. Data enters as **MPDU in** and exits as **MPDU out**. +- Physical coding (PCS) (generation of PHY-frame, mapping MAC frames into the PHY-frame):** The first sublayer. It receives **MPDU in** and sends **TX PHY frame** to the PMA. It receives **RX PHY frame** from the PMA and sends **MPDU out** to the MAC. It has a bidirectional control connection with **PHY management** labeled **PCS control data**. +- $\alpha$ -reference point:** The boundary between the PCS and the PMA. +- Physical media attachment (PMA) (scrambling, FEC, spatial stream parsing, segmentation to OFDM symbols, padding):** The second sublayer. It receives **TX PHY frame** from the PCS and sends **TX symbol frames** to the PMD. It receives **RX symbol frames** from the PMD and sends **RX PHY frame** to the PCS. It has a bidirectional control connection with **PHY management** labeled **PMA control data**. +- $\delta$ -reference point:** The boundary between the PMA and the PMD. +- Physical medium dependent (PMD) (tone mapping, constellation encoding, Tx ports mapping, OFDM modulation, preamble insertion, carrier sense generation):** The third sublayer. It receives **TX symbol frames** from the PMA and transmits them over the **Transmission medium**. It receives signals from the **Transmission medium** and sends **RX symbol frames** to the PMA. It has a bidirectional control connection with **PHY management** labeled **PMD control data**. +- MDI (Medium Dependent Interface):** The interface between the PMD and the **Transmission medium**. +- PHY management:** A vertical line on the right representing the management interface, connected to the PCS, PMA, and PMD sublayers. + +G.9963(15)-Amd.1(16)\_F7-1 + +Figure 7-1 – PHY functional model of the MIMO transceiver. The diagram shows the flow of data from the MAC (PMI) through the Physical coding (PCS), Physical media attachment (PMA), and Physical medium dependent (PMD) sublayers to the Transmission medium (MDI). It also shows the receive path and control signals from PHY management. + +**Figure 7-1 – PHY functional model of the MIMO transceiver** + +In the transmit direction, data enters the PHY from the MAC via the PMI in blocks of bytes called MAC protocol data units (MPDUs). The incoming MPDU is mapped into a PHY frame in the PCS. The PHY frame is scrambled, encoded and parsed into spatial streams (SS), which are then segmented into orthogonal frequency division multiplexing (OFDM) symbol frames in the PMA. The symbol frames of each of the spatial streams is mapped to OFDM sub-carriers, modulated and mapped to Tx ports in the PMD and transmitted over the medium using OFDM modulation with relevant parameters. In the PMD, a preamble is added to assist synchronization and channel estimation in the receiver. + +In the receive direction, frames entering from the medium (reception is also done via multiple Rx ports) via the MDI are demodulated and decoded. The recovered MPDUs are forwarded to the MAC via the PMI. The recovered PHY-frame headers (PFH) are processed in the PHY to extract the relevant frame parameters specified in clause 7.1.2.3. + +### 7.1.2 Physical coding sublayer (PCS) + +The functional model of the PCS is presented in Figure 7-2. It is intended to describe in more detail the PCS functional block presented in Figure 7-1. + +![Functional model of PCS diagram showing transmit and receive paths between PMI, MPDU mapper/de-mapper, Header generation/processing, MUX (TDM), and PHY management.](d4af765160d04ecef538e5066006dc77_img.jpg) + +The diagram illustrates the functional model of the Physical Coding Sublayer (PCS). It is divided into two main paths: transmit (left) and receive (right), separated by a vertical line representing the PHY management entity. + +Transmit path: An arrow labeled 'MPDU in' enters from the top (PMI) into an 'MPDU mapper' block. The output of the mapper goes to a 'MUX (TDM)' block. A 'Header generation' block is connected to the MPDU mapper and the MUX (TDM). The output of the MUX (TDM) is labeled 'TX PHY frame' and passes through a dashed line labeled 'α-reference point'. + +Receive path: An arrow labeled 'RX PHY frame' enters from the bottom (PHY management) through the 'α-reference point' into a 'Header processing' block. The output of the header processing block goes to an 'MPDU de-mapper' block. A 'PCS control data' arrow points from the header processing block to the PHY management. The output of the MPDU de-mapper is labeled 'MPDU out' and points to the PMI. + +Other labels: 'G.9963(11)\_F7-2' is at the bottom right. + +Functional model of PCS diagram showing transmit and receive paths between PMI, MPDU mapper/de-mapper, Header generation/processing, MUX (TDM), and PHY management. + +**Figure 7-2 – Functional model of PCS** + +In the transmit direction, the incoming MPDU is mapped into a payload field of a PHY frame (clause 7.1.2.1) as described in clause 7.1.2.2. The PHY-frame header (clause 7.1.2.3) is then added to form a TX PHY frame. The TX PHY frame is passed across the $\alpha$ -reference point for further processing in the PMA. + +In the receive direction, the decoded PHY-frame payload and header are processed and originally transmitted MPDUs are recovered from the payloads of received PHY frames and submitted to the PMI. Relevant control information conveyed in the PHY-frame header is processed and submitted to the PHY management entity. + +#### 7.1.2.1 PHY frame + +As stated in clause 7.1.1, a MIMO transceiver shall be capable of transmitting using the following two transmission schemes: + +- ITU-T G.9960 transmission based on the reference models and PHY frame format defined in [ITU-T G.9960]. +- MIMO transmission based on the reference models and PHY frame format defined in this Recommendation. + +The format of the PHY frame for ITU-T G.9960 transmission is presented in clause 7.1.2.1 of [ITU-T G.9960]. The format of the PHY frame for MIMO transmission is presented in this section. + +Table 7-1 specifies the transmission rule (PHY frame format) that shall be used by an ITU-T G.9963 node when it transmits to an ITU-T G.9960/G.9961 node or to an ITU-T G.9963 node, or both. + +**Table 7-1 – Transmission rule (PHY frame format) for an ITU-T G.9963 node depending on the type of intended receiver** + +| | Source devices | Destination devices | Number of spatial streams for payload | MIMO_IND | Transmission details | Transmission scheme | +|----|----------------|---------------------------------|---------------------------------------|----------|---------------------------------------------------------------------------------------------------------|-------------------------------------------------------| +| 1 | ITU-T G.9963 | ITU-T G.9963 | N/A | N/A | Frames without payload intended for ITU-T G.9963 receivers (e.g., RTS, CTS, ACK, ACKRQ) | MIMO transmission or ITU-T G.9960 transmission (Note) | +| 2 | ITU-T G.9963 | [ITU-T G.9960] | N/A | N/A | Frames without payload intended for ITU-T G.9960 receivers | MIMO transmission or ITU-T G.9960 transmission (Note) | +| 3 | ITU-T G.9963 | ITU-T G.9963 and [ITU-T G.9960] | N/A | N/A | Frames without payload intended for ITU-T G.9963 and ITU-T G.9960 receivers (no such frame type exists) | N/A | +| 4a | ITU-T G.9963 | ITU-T G.9963 | 2 | 1 | Frames with payload intended for ITU-T G.9963 receivers (e.g., MSG, BMSG, BACK, PROBE) | MIMO transmission | +| 4b | | | 1 | 0 | | MIMO transmission or ITU-T G.9960 transmission (Note) | +| 5 | ITU-T G.9963 | [ITU-T G.9960] | 1 | 0 | Frames with payload intended for ITU-T G.9960 receivers | MIMO transmission or ITU-T G.9960 transmission (Note) | +| 6 | ITU-T G.9963 | ITU-T G.9963 and [ITU-T G.9960] | 1 | 0 | Frames with payload intended for ITU-T G.9963 and ITU-T G.9960 receivers (e.g., broadcast, MAP) | MIMO transmission or ITU-T G.9960 transmission (Note) | +| 7 | ITU-T G.9963 | ITU-T G.9963 and [ITU-T G.9960] | N/A | N/A | Signals (e.g., INUSE, PR, NACK, IDPS) | MIMO transmission or ITU-T G.9960 transmission (Note) | + +NOTE – The decision concerning which scheme to use shall be made by the source device at the time of registration and shall not change as long as the device is still registered, regardless of the type of destination device it is communicating with. + +The format of the PHY frame for MIMO transmission is presented in Figure 7-3. The PHY frame at the $\alpha$ -reference point includes a header and a payload. The preamble and additional channel estimation (ACE) symbols are added to the PHY frame in the PMD. Both the preamble and ACE symbols do not carry any user or management data and are intended for synchronization and channel + +estimation. At the MDI interface the transmission shall adhere to the following (as described in detail in clause 7.1.4): + +- The preamble/header/ACE symbol(s)/payload shall be transmitted simultaneously on both Tx ports. +- The preamble and header symbol(s) to be transmitted on the second Tx port shall be copies of the preamble and header symbol(s) to be transmitted on the first Tx port. +- The payload may be created as either two spatial streams (indicated by setting the field MIMO\_IND in the PFH to one) or a single spatial stream (indicated by setting the field MIMO\_IND in the PFH to zero). +- ACE symbols: + - For the case where the transmission is created as two spatial streams (i.e., case "4a" in Table 7-1): + - The odd numbered ACE symbols (starting from the first ACE symbol, which is odd numbered) to be transmitted on the second Tx port shall be inverted versions of the same numbered ACE symbols to be transmitted on the first Tx port. + - The even numbered ACE symbols to be transmitted on the second Tx port shall be identical to the same numbered ACE symbols to be transmitted on the first Tx port. + For this case one ACE symbol is mandatory. Additional ACE symbols are optional. + - In all other cases where the transmission includes payload created as a single spatial stream (i.e., cases "4b", "5" and "6" in Table 7-1), the ACE symbols to be transmitted on the second Tx port shall be identical to the same numbered ACE symbols to be transmitted on the first Tx port. In these cases all ACE symbols are optional. +- Transmission on the second Tx port shall be done with a cyclic shift with respect to the transmission on the first TX port. + +![Diagram showing the format of the PHY frame in a MIMO transmission. It consists of two rows representing Tx port #1 and Tx port #2. Each row is divided into four colored segments: Preamble (blue), Header (green, 1, 2 or 4 symbols), ACE symbol(s) (orange), and Payload (white). For Tx port #2, the segments are labeled with '(with CS)' to indicate cyclic shift.](4ee27dbf5ef12e7b58b0ef0937bc5a5e_img.jpg) + +| | | | | | +|------------|--------------------|---------------------------------------|-------------------------|----------------------| +| Tx port #1 | Preamble | Header
1, 2 or 4 symbols | ACE symbol(s) | Payload #1 | +| Tx port #2 | Preamble (with CS) | Header (with CS)
1, 2 or 4 symbols | ACE symbol(s) (with CS) | Payload #2 (with CS) | + +G.9963(11)\_F7-3 + +Diagram showing the format of the PHY frame in a MIMO transmission. It consists of two rows representing Tx port #1 and Tx port #2. Each row is divided into four colored segments: Preamble (blue), Header (green, 1, 2 or 4 symbols), ACE symbol(s) (orange), and Payload (white). For Tx port #2, the segments are labeled with '(with CS)' to indicate cyclic shift. + +**Figure 7-3 – Format of the PHY frame in a MIMO transmission** + +The PHY-frame header and payload shall each contain an integer number of OFDM symbols. + +The PHY-frame header always fits into an integer number of OFDM symbols and is transmitted using a single predefined set of modulation and coding parameters (see clause 7.1.3.4). + +The presence of ACE symbols is frame type dependent (e.g., see clause 7.1.2.3.2.2.17). + +The length of the payload may vary from frame to frame; the payload may be of zero length. For the payload, different coding parameters and bit loading can be used in different frames, depending on the channel/noise characteristics and QoS requirements. + +For all of the cases shown in Table 7-1 where a node can choose either ITU-T G.9960 transmission or MIMO transmission, the node shall select one transmission rule at the time of registration and shall not change this decision as long as it is still registered. For example, if a node decides to use ITU-T G.9960 transmission rule, it shall use ITU-T G.9960 transmission rule for cases 1, 2, 4b, 5, 6 and 7. A node may select a different transmission rule if it resigns from a domain and re-registers to the domain. + +NOTE – Since the transmission rule for a given node for a single spatial stream does not change from frame to frame, the channels perceived by other nodes in the domain are consistent from frame to frame. + +The types of PHY frames used in this Recommendation are summarized in Table 7-1 of [ITU-T G.9960]. + +#### 7.1.2.2 MPDU mapping + +See clause 7.1.2.2 of [ITU-T G.9960]. + +#### 7.1.2.3 PHY-frame header + +See clause 7.1.2.3 of [ITU-T G.9960]. + +##### 7.1.2.3.1 Common part fields + +See clause 7.1.2.3.1 of [ITU-T G.9960]. + +##### 7.1.2.3.2 Variable part fields + +See clause 7.1.2.3.2 of [ITU-T G.9960]. + +###### 7.1.2.3.2.1 MAP and RMAP PHY-frame type specific fields + +See clause 7.1.2.3.2.1 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2 MSG PHY-frame type specific fields + +Table 7-2 lists the PHY-frame header fields specific to the MSG frame type. + +**Table 7-2 – MSG PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|----------------|---------|--------|----------------------------------------------------------------------------------------------|-----------------------| +| MSG_DUR | 0 and 1 | [15:0] | Duration for MSG frame | Clause 7.1.2.3.2.2.1 | +| BLKSZ | 2 | [1:0] | Block size of FEC codeword for MSG frame payload | Clause 7.1.2.3.2.2.2 | +| FEC_RATE | | [4:2] | FEC coding rate for MSG frame payload | Clause 7.1.2.3.2.2.3 | +| REP | | [7:5] | Number of repetitions used for encoding the MSG frame payload | Clause 7.1.2.3.2.2.4 | +| FCF | 3 | [2:0] | FEC concatenation factor | Clause 7.1.2.3.2.2.5 | +| SI | | [6:3] | Scrambler initialization | Clause 7.1.2.3.2.2.6 | +| MDET | | [7] | Master is detected | Clause 7.1.2.3.2.2.7 | +| BAT_ID/BMAT_ID | 4 | [4:0] | Bit allocation table identifier/Bit and Tx port mapping allocation table identifier for MIMO | Clause 7.1.2.3.2.2.8 | +| OFB/GRP_ID | | [7:5] | OFB identifier/sub-carrier grouping identifier | Clause 7.1.2.3.2.2.9 | +| GI_ID | 5 | [2:0] | Guard interval identifier | Clause 7.1.2.3.2.2.10 | +| APSD_MAX-M | | [7:3] | APSD_MAX-M of a MSG frame | Clause 7.1.2.3.2.2.11 | +| CONNECTION_ID | 6 | [7:0] | Connection identifier | Clause 7.1.2.3.2.2.12 | +| RPRQ | 7 | [1:0] | Reply required | Clause 7.1.2.3.2.2.13 | +| BRSTCnt | | [3:2] | Burst frame count | Clause 7.1.2.3.2.2.14 | + +**Table 7-2 – MSG PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|------------------|----------|--------|------------------------------------------------------------------------|----------------------------------| +| BEF | | [4] | Burst end flag | Clause 7.1.2.3.2.2.15 | +| AIFG_IND | | [5] | AIFG indication | clause 7.1.2.3.2.2.16 | +| MIMO_IND | | [6] | MIMO indication | Clause 7.1.2.3.2.2.24 | +| APSD_MAX_M_EXT | | [7] | APSD_MAX-M extension | Clause 7.1.2.3.2.2.26 | +| ACE_SYM | 8 | [2:0] | Number of ACE symbols | Clause 7.1.2.3.2.2.17 | +| CNN_MNGMT | | [6:3] | Connection management | Clause 7.1.2.3.2.2.18 | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note 1) | +| BRURQ | 9 and 10 | [15:0] | Bandwidth reservation update request | Clause 7.1.2.3.2.2.19 (Note 2) | +| START_SSN | 9 and 10 | [15:0] | Start segment sequence number | Clause 7.1.2.3.2.2.20 (Note 3) | +| CURRTS | 11 | [6:0] | Current TS | Clause 7.1.2.3.2.2.21 | +| BTXRQ | | [7] | Request for bidirectional transmission | Clause 7.1.2.3.2.2.22 | +| NUM_MCACK_SLOTS | 12 | [2:0] | Number of Mc-ACK slots | Clause 7.1.2.3.2.2.23 | +| ADVISED_WIN_SIZE | | [7:3] | In connection establishment this field may specify advised window size | Clause 7.1.2.3.2.2.25 (Note 4) | +| Reserved | 13 | [0] | Reserved | Reserved for use by ITU-T G.9991 | +| Reserved | | [7:1] | Reserved | Reserved by ITU-T (Note 1) | +| Reserved | 14 | [7:0] | Reserved | Reserved by ITU-T (Note 1) | + +NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. +NOTE 2 – The BRURQ field is defined when the START\_SSN field is not defined (see Note 3). +NOTE 3 – The START\_SSN field is defined only when CNN\_MNGMT = 0001, CNN\_MNGMT = 0011, CNN\_MNGMT = 0101 or CNN\_MNGMT = 0111. Otherwise, the meaning of this field is BRURQ. +NOTE 4 – The ADVISED\_WIN\_SIZE field is defined only when CNN\_MNGMT = 0101, otherwise these bits are reserved by ITU-T and shall be set to zero by the transmitter and ignored by the receiver. + +###### 7.1.2.3.2.2.1 Duration for MSG frame (MSG\_DUR) + +See clause 7.1.2.3.2.2.1 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.2 Block size (BLKSZ) + +See clause 7.1.2.3.2.2.2 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.3 FEC coding rate (FEC\_RATE) + +See clause 7.1.2.3.2.2.3 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.4 Repetitions (REP) + +See clause 7.1.2.3.2.2.4 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.5 FEC concatenation factor (FCF)** + +See clause 7.1.2.3.2.2.5 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.6 Scrambler initialization (SI)** + +See clause 7.1.2.3.2.2.6 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.7 Master is detected indication (MDET)** + +See clause 7.1.2.3.2.2.7 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.8 Bit allocation table identifier / Bit and Tx port mapping allocation table for MIMO (BAT\_ID/BMAT\_ID)** + +When this field is interpreted as BAT\_ID (i.e., when MIMO\_IND = 0), see clause 7.1.2.3.2.2.8 of [ITU-T G.9960]. + +When this field is interpreted as BMAT\_ID (i.e., when MIMO\_IND = 1), the BMAT\_ID field shall identify the BMAT, which is composed of the following elements: + +- The bit allocation tables (BATs) of the two spatial streams of the PHY frame (i.e., the BAT of spatial stream 1, BAT(1) and the BAT of spatial stream 2, BAT(2)). +- The Tx port mapping allocation table (MAT) of the PHY frame. + +The BMAT\_ID shall be represented as a 5-bit unsigned integer with valid values assigned as shown in Table 7-3. + +**Table 7-3 – Assignment of BMAT\_ID** + +| BMAT_ID | Type of MAT | Type of BAT (1) | Type of BAT (2) | Description | | +|---------|------------------------|----------------------------|----------------------------|--------------------------------------------------------|--| +| 0 | Predefined MAT, Type 0 | Predefined-BAT, Type 0 | Note 1 | Predefined BMAT, single port transmission on Tx port 1 | | +| 1 | Predefined MAT, Type 0 | Predefined-BAT, Type 1 | | | | +| 2 | Predefined MAT, Type 0 | Predefined-BAT, Type 3 | Note 2 | | | +| 3 | Predefined MAT, Type 0 | Predefined-BAT, Type 2 | | | | +| 4 | Predefined MAT, Type 1 | Note 1 | Predefined-BAT, Type 0 | Predefined BMAT, single port transmission on Tx port 2 | | +| 5 | Predefined MAT, Type 1 | | Predefined-BAT, Type 1 | | | +| 6 | Predefined MAT, Type 1 | Note 2 | Predefined-BAT, Type 3 | | | +| 7 | Predefined MAT, Type 1 | | Predefined-BAT, Type 2 | | | +| 8 | Predefined MAT, Type 2 | Predefined-BAT, Type 0 | Predefined-BAT, Type 0 | Predefined BMAT, MIMO, direct mapping (TPM #0) | | +| 9 | Predefined MAT, Type 2 | Predefined-BAT, Type 1 | Predefined-BAT, Type 1 | | | +| 10 | Predefined MAT, Type 2 | Predefined-BAT, Type 3 | Predefined-BAT, Type 3 | | | +| 11 | Predefined MAT, Type 2 | Predefined-BAT, Type 2 | Predefined-BAT, Type 2 | | | + +**Table 7-3 – Assignment of BMAT\_ID** + +| BMAT_ID | Type of MAT | Type of BAT(1) | Type of BAT(2) | Description | +|----------------|---------------------------------------|---------------------------------------|---------------------------------------|----------------------------------------| +| 12 to 15 | Reserved by ITU-T for predefined MATs | Reserved by ITU-T for predefined BATs | Reserved by ITU-T for predefined BATs | Reserved by ITU-T for predefined BMATs | +| 16 to 27 | Runtime MATs | Runtime BATs | Runtime BATs | Runtime BMATs, Runtime MATs and BATs | +| 28 to 31 | Reserved by ITU-T | Reserved by ITU-T | Reserved by ITU-T | Reserved by ITU-T | + +NOTE 1 – The BAT is a uniform 0-bit loading on all sub-carriers except the PMSC set (i.e., no data bits are loaded on this spatial stream). +NOTE 2 – The BAT is uniform 0-bit loading on all sub-carriers except the PMSC set and the RMSC sets (a complete SSC set) (i.e., no data bits are loaded on this spatial stream). + +One or more BMAT\_IDs can be assigned for each destination (per unicast DID, see clause 7.1.2.3.1.5 of [ITU-T G.9960]). + +###### **7.1.2.3.2.2.9 OFB identifier/sub-carrier grouping identifier (OFB\_ID/GRP\_ID)** + +If MIMO\_IND is set to zero, see clause 7.1.2.3.2.2.9 of [ITU-T G.9960]. + +If MIMO\_IND is set to one, the following applies. + +For predefined BMATs with uniform loading (using predefined BATs of type 0, type 1, type 2 or type 3), the OFB\_ID field shall contain the identifier for the operational frequency band used by the node and shall be coded as shown in Table 7-10 of [ITU-T G.9960]. + +For Runtime BMATs, this field shall be set at 0 by the transmitter and ignored by the receiver. + +###### **7.1.2.3.2.2.10 Guard interval identifier (GI\_ID)** + +See clause 7.1.2.3.2.2.10 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.11 Maximum Actual PSD of MSG frame (APSD\_MAX-M)** + +See clause 7.1.2.3.2.2.11 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.12 Connection identifier (CONNECTION\_ID)** + +See clause 7.1.2.3.2.2.12 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.13 Reply required (RPRQ)** + +See clause 7.1.2.3.2.2.13 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.14 Burst frame count (BRSTCnt)** + +See clause 7.1.2.3.2.2.14 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.15 Burst end flag (BEF)** + +See clause 7.1.2.3.2.2.15 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.16 AIFG indication (AIFG\_IND)** + +See clause 7.1.2.3.2.2.16 of [ITU-T G.9960]. + +###### **7.1.2.3.2.2.17 ACE symbols (ACE\_SYM)** + +See clause 7.1.2.3.2.2.17 of [ITU-T G.9960]. + +If MIMO\_IND is set to one, ACE\_SYM shall not be set to 0002. + +###### 7.1.2.3.2.2.18 Connection management (CNN\_MNGMT) + +See clause 7.1.2.3.2.2.18 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.19 Bandwidth reservation update request (BRURQ) + +See clause 7.1.2.3.2.2.19 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.20 Start segment sequence number (START\_SSN) + +See clause 7.1.2.3.2.2.20 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.21 Current TS (CURRTS) + +See clause 7.1.2.3.2.2.21 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.22 Request for bidirectional transmission (BTXRQ) + +See clause 7.1.2.3.2.2.22 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.23 Number of Mc-ACK slots (NUM\_MCACK\_SLOTS) + +See clause 7.1.2.3.2.2.23 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.24 MIMO indication (MIMO\_IND) + +The MIMO\_IND field indicates a MIMO transmission with the payload created as 2 spatial streams intended for ITU-T G.9963 receivers (i.e., case "4a" in Table 7-1). This requires at least one additional channel estimation (ACE) symbol after the PHY-frame header (PFH). + +It is a 1-bit field. It shall be set to one for case "4a" in Table 7-1. It shall be set to zero for all other applicable cases (i.e., cases "4b", "5" and "6" in Table 7-1). + +###### 7.1.2.3.2.2.25 Advised window size (ADVISED\_WIN\_SIZE) + +See clause 7.1.2.3.2.2.24 of [ITU-T G.9960]. + +###### 7.1.2.3.2.2.26 APSD\_MAX-M extension + +See clause 7.1.2.3.2.2.25 of [ITU-T G.9960]. + +###### 7.1.2.3.2.3 ACK PHY-frame type specific fields + +Table 7-4 lists the PHY-frame header fields specific to the core part of the PHY-frame header of the ACK frame type. + +**Table 7-4 – ACK PHY frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|-------------|-------|-------|------------------------------|-----------------------------------------| +| FLCTRL_CONN | 0 | [0] | Flow control connection flag | Clause 7.1.2.3.2.3.1 of [ITU-T G.9960] | +| FLCTRLT | | [1] | Flow control type | Clause 7.1.2.3.2.3.2 of [ITU-T G.9960] | +| FLCTRL | | [6:2] | Flow control | Clause 7.1.2.3.2.3.3 of [ITU-T G.9960] | +| FLCTRL_EXT | | [7] | Flow control extension | Clause 7.1.2.3.2.3.11 of [ITU-T G.9960] | +| RXRST_DATA | 1 | [0] | Data RX reset flag | Clause 7.1.2.3.2.3.5 of [ITU-T G.9960] | + +**Table 7-4 – ACK PHY frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|------------------------------|---------|---------|---------------------------------------------------------------------------------|-----------------------------------------| +| RXRST_MNGMT | | [1] | Management RX reset flag | Clause 7.1.2.3.2.3.6 of [ITU-T G.9960] | +| BAD_BURST | | [2] | Bad burst indication | Clause 7.1.2.3.2.3.7 of [ITU-T G.9960] | +| BTXRQ | | [3] | Request for bidirectional transmission | Clause 7.1.2.3.2.3.4 of [ITU-T G.9960] | +| EXTACKRQ | | [4] | Request for extended acknowledgement | Clause 7.1.2.3.2.3.10 of [ITU-T G.9960] | +| Reserved | | [7:5] | Reserved | Reserved for use by [ITU-T G.9991] | +| ACK_CE_CTRL/RX_CONN_WIN_SIZE | 2 | [7:0] | ACK channel estimation control/Receiver window size for the connection (Note 1) | Clause 7.1.2.3.2.3.1 | +| ACKDATA/MCACK_D | 3 to 14 | [90:0] | Acknowledgement data and Mc-ACK descriptor | Clause 7.1.2.3.2.3.9 of [ITU-T G.9960] | +| Reserved | | [95:91] | Reserved | Reserved by ITU-T (Note 2) | + +NOTE 1 – This field is interpreted as RX\_CONN\_WIN\_SIZE only when the ACK frame is sent as a reply for MSG frame requesting setup or reset of either a data or a management connection (i.e., when CNN\_MNGMT in the MSG frame is 01012, 00012, 00112 or 01112). + +NOTE 2 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +###### 7.1.2.3.2.3.1 ACK channel estimation control/Receiver window size for the connection (ACK\_CE\_CTRL/RX\_CONN\_WIN\_SIZE) + +In case of an ACK frame sent in response to a MSG frame requesting setup or reset of a data or management connection with acknowledgements (i.e., when CNN\_MNGMT in the MSG frame for connection setup is 01012, 00012, 00112 or 01112 see Table 7-17 of [ITU-T G.9960]), this parameter is called RX\_CONN\_WIN\_SIZE and the value of this parameter shall indicate the maximum acknowledge window size (i.e., ACK\_RX\_CONF\_WINDOW\_SIZE in clause 8.9.4.3 in [ITU-T G.9961]) that the receiver can support for the connection being setup. The maximum acknowledge window size shall be 8 times the value of (RX\_CONN\_WIN\_SIZE+1) LPDUs. The valid values for the maximum acknowledge window size shall be 8, 16, 24 ... 1024 LPDUs. The indicated value of maximum acknowledge window size shall be less than or equal to ACK\_MAX\_WINDOW\_SIZE (1024 for data connections, 32 for management connections – see clause 8.9.4.1 in [ITU-T G.9961]). + +For all other ACK frames, this field is called, ACK\_CE\_CTRL and is used for channel estimation control. It is an 8-bit field that consists of the ACK\_CE\_CTRL\_TYPE, the RUNTIME\_BAT\_ID/RUNTIME\_BMAT\_ID and the RUNTIME\_BMAT\_ID fields as shown in Table 7-5. + +**Table 7-5 – Interpretation of the ACK\_CE\_CTRL field** + +| Field | Octet | Bits | +|--------------------------------|-------|-------| +| ACK_CE_CTRL_TYPE | 0 | [1:0] | +| RUNTIME_BAT_ID/RUNTIME_BMAT_ID | | [6:2] | +| BMAT_ID_IND | | [7] | + +###### **7.1.2.3.2.3.1.1 ACK channel estimation control type (ACK\_CE\_CTRL\_TYPE)** + +When BMAT\_ID\_IND equals 0, ACK\_CE\_CTRL\_TYPE shall be coded as shown in Table 7-25 of [ITU-T G.9960] as specified in clause 7.1.2.3.2.3.8.1 of [ITU-T G.9960]. + +When BMAT\_ID\_IND equals 1, ACK\_CE\_CTRL\_TYPE shall be coded as shown in Table 7-6. + +**Table 7-6 – ACK\_CE\_CTRL\_TYPE field values when BMAT\_ID\_IND = 1** + +| ACK_CE_CTRL_TYPE value (b 1 b 0 ) | Interpretation | +|---------------------------------------------------------|-------------------------------------------| +| 00 | No ACK_CE_CTRL information is transmitted | +| 01 | RUNTIME_BMAT_ID is invalid | +| 10 | Request PROBE frame transmission. | +| 11 | Reserved by ITU-T | + +If the BMAT\_ID\_IND field equals 1 and the ACK\_CE\_CTRL\_TYPE field is set to 012, the runtime BMAT associated with the RUNTIME\_BMAT\_ID shall not be used for transmission, as specified in clause 8.11.1.5. + +If the BMAT\_ID\_IND field equals 1 and the ACK\_CE\_CTRL\_TYPE field is set to 102, transmission of a 2 SS channel estimation PROBE frame is requested. + +Otherwise, the ACK\_CE\_CTRL\_TYPE field shall be set to 002. + +###### **7.1.2.3.2.3.1.2 Runtime BAT\_ID (RUNTIME\_BAT\_ID)/Runtime BMAT ID (RUNTIME\_BMAT\_ID)** + +When this field is interpreted as RUNTIME\_BAT\_ID (i.e., when BMAT\_ID\_IND = 0), see clause 7.1.2.3.2.3.8.2 of [ITU-T G.9960]. + +When this field is interpreted as RUNTIME\_BMAT\_ID (i.e., when BMAT\_ID\_IND = 1), the following applies. + +If the ACK\_CE\_CTRL\_TYPE field is set to 012, this field shall contain a RUNTIME\_BMAT\_ID (see Table 7-3). Otherwise, it shall be set to 000002. + +###### **7.1.2.3.2.3.1.3 BMAT\_ID indication (BMAT\_ID\_IND)** + +If the BMAT\_ID\_IND field is set to 0, the interpretation of the other subfields in the ACK\_CE\_CTRL shall be as described in [ITU-T G.9960]. + +If the BMAT\_ID\_IND field is set to 1, the interpretation of the other subfields in the ACK\_CE\_CTRL shall be as described in this Recommendation. + +###### **7.1.2.3.2.4 RTS PHY-frame type specific fields** + +See clause 7.1.2.3.2.4 of [ITU-T G.9960]. + +###### **7.1.2.3.2.5 CTS PHY-frame type specific fields** + +See clause 7.1.2.3.2.5 of [ITU-T G.9960]. + +###### 7.1.2.3.2.6 CTMG PHY-frame type specific fields + +See clause 7.1.2.3.2.6 of [ITU-T G.9960]. + +###### 7.1.2.3.2.7 PROBE PHY-frame type specific fields + +The PROBE PHY-frame type specific field is composed of a common part and a variable part. The common part contains fields that are common for all PROBE PHY-frame types (PRBTYPES). The variable part contains fields that are specific to each PRBTYPE. + +The fields of the common part of the PROBE PHY-frame specific field are defined in Table 7-7. + +**Table 7-7 – PROBE PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|----------------|---------|--------|---------------------------------|--------------------------| +| Common part | | | | | +| PRB_DUR | 0 and 1 | [15:0] | Duration for PROBE frame | Clause 7.1.2.3.2.7.1.1 | +| PRBTYPE | 2 | [3:0] | PROBE frame type | Clause 7.1.2.3.2.7.1.2 | +| PRBSYM | | [7:4] | Probe symbols | Clause 7.1.2.3.2.7.1.3 | +| APSD_MAX-P | 3 | [4:0] | APSD_MAX-P of a PROBE frame | Clause 7.1.2.3.2.7.1.4 | +| PRBGI | | [7:5] | Probe symbol guard interval | Clause 7.1.2.3.2.7.1.5 | +| CURRTS | 4 | [6:0] | Current TS | Clause 7.1.2.3.2.7.1.6 | +| MIMO_IND | | [7] | MIMO indication | Clause 7.1.2.3.2.7.1.7 | +| APSD_MAX-P_EXT | 5 | [0] | APSD_MAX-P Extension | Clause 7.1.2.3.2.7.1.8 | +| Reserved | | [7:1] | Reserved | Reserved by ITU-T (Note) | +| Variable part | | | | | +| PFTSF | 6 to 14 | [71:0] | PROBE frame type specific field | Clause 7.1.2.3.2.7.2 | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +###### 7.1.2.3.2.7.1 Common part fields + +###### 7.1.2.3.2.7.1.1 Duration for PROBE frame (PRB\_DUR) + +See clause 7.1.2.3.2.7.1.1 of [ITU-T G.9960]. + +###### 7.1.2.3.2.7.1.2 PROBE frame type (PRBTYPE) + +The PRBTYPE field shall contain the type of the PROBE frame. It is a 4-bit field that shall be coded as shown in Table 7-8. + +**Table 7-8 – PRBTTYPE field values** + +| PRBTTYPE value
(b3b2b1b0) | Interpretation | Reference | MIMO_IND | +|----------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------|-----------------| +| 0000 | Silent PROBE frame – a PHY frame in which the probe symbols composing the payload shall all be silent symbols, as specified in clause 7.1.3.7. | Clause 7.1.2.3.2.7.2.1 | 0 | +| 0001 | 1 SS channel estimation PROBE frame – a PHY frame in which the probe symbols composing the payload shall all be 1 SS channel estimation probe symbols, as specified in clause 7.1.3.7. | Clause 7.1.2.3.2.7.2.2 | 0 | +| 0010 to 0111 | Reserved by ITU-T. | | Reserved | +| 1000 | 2 SS channel estimation PROBE frame – a PHY frame in which the probe symbols composing the payload shall all be 2 SS channel estimation probe symbols, as specified in clause 7.1.3.7. | Clause 7.1.2.3.2.7.2.3 | 1 | +| 1001 to 1111 | Reserved by ITU-T. | | Reserved | + +###### **7.1.2.3.2.7.1.3 Probe symbols (PRBSYM)** + +See clause 7.1.2.3.2.7.1.3 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.1.4 Maximum Actual PSD of PROBE frame (APSD\_MAX-P)** + +See clause 7.1.2.3.2.7.1.4 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.1.5 PROBE symbol guard interval (PRBGI)** + +See clause 7.1.2.3.2.7.1.5 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.1.6 Current TS (CURRTS)** + +See clause 7.1.2.3.2.7.6 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.1.7 MIMO indication (MIMO\_IND)** + +See clause 7.1.2.3.2.2.24. + +###### **7.1.2.3.2.7.1.8 APSD\_MAX-P Extension** + +See clause 7.1.2.3.2.7.1.7 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.2 PROBE frame type specific fields** + +###### **7.1.2.3.2.7.2.1 Silent PROBE frame specific fields** + +See clause 7.1.2.3.2.7.2.1 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.2.2 1 SS channel estimation PROBE frame specific fields** + +See clause 7.1.2.3.2.7.2.2 of [ITU-T G.9960]. + +###### **7.1.2.3.2.7.2.3 2 SS channel estimation PROBE frame specific fields** + +The fields of the specific part of the 2 SS channel estimation PROBE frame are defined in Table 7-9. + +**Table 7-9 – 2 SS channel estimation PROBE frame specific field values** + +| Field | Octet | Bits | Description | Reference | +|-------------------------------------------------------------------------------------------------------------|--------|--------|------------------------------------|--------------------------| +| PRB_BMAT_ID | 0 | [4:0] | BMAT_ID used to generate the PROBE | Clause 7.1.2.3.2.7.2.3.1 | +| ACE_SYM | 0 | [7:5] | Number of ACE symbols | Clause 7.1.2.3.2.7.2.3.2 | +| NUM_SILENT_SYM | 1 | [5:0] | Number of silent symbols | Clause 7.1.2.3.2.7.2.3.3 | +| Reserved | 1 | [7:6] | Reserved by ITU-T (Note) | | +| Reserved | 2 to 8 | [55:0] | Reserved by ITU-T (Note) | | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | | + +###### 7.1.2.3.2.7.2.3.1 PROBE frame BMAT\_ID (PRB\_BMAT\_ID) + +This field indicates the BMAT\_ID (predefined or runtime) whose mapping allocation table (MAT) is used in the Tx port mapper to generate this 2 SS channel estimation PROBE frame. The bit allocation tables (BATs) associated with the BMAT\_ID are only relevant to infer the Tx port mapping (TPMs) used per sub-carrier (see Table 8-27) for 2 SS channel estimation probe symbol generation (see clause 7.1.4.2.4.3). Therefore, if the PRB\_BMAT\_ID conveys a predefined BMAT\_ID, the valid values for channel estimation shall be 3, 7 and 11. + +NOTE – The PRB\_BMAT\_ID field allows transmitting PROBES using the precoding parameters associated with a given runtime BMAT\_ID. + +###### 7.1.2.3.2.7.2.3.2 ACE symbols (ACE\_SYM) + +See clause 7.1.2.3.2.2.17 of [ITU-T G.9960]. + +If MIMO\_IND is set to one, ACE\_SYM shall not be set to 0002. + +###### 7.1.2.3.2.7.2.3.3 Number of silent symbols (NUM\_SILENT\_SYM) + +This field indicates the number of silent symbols that shall be transmitted instead of probe symbols at the end of the 2 SS channel estimation PROBE frame. The valid range is from 0 (no silent symbol) to 63 (63 silent symbols). NUM\_SILENT\_SYM shall be less than or equal to PRBSYM. First (PRBSYM – NUM\_SILENT\_SYM) symbols of the 2 SS channel estimation PROBE frame are normal (non-silent) probe symbols. + +###### 7.1.2.3.2.8 ACKRQ PHY frame type specific fields + +See clause 7.1.2.3.2.8 of [ITU-T G.9960]. + +###### 7.1.2.3.2.9 BMSG PHY-frame type specific fields + +Table 7-10 lists the fields specific to the core part of the PHY-frame header of the BMSG frame type. + +**Table 7-10 – BMSG PHY-frame type specific fields – core part** + +| Field | Octet | Bits | Description | Reference | +|----------|---------|--------|---------------------------------------------------|----------------------| +| BMSG_DUR | 0 and 1 | [15:0] | Duration for BMSG frame | Clause 7.1.2.3.2.9.1 | +| BLKSZ | 2 | [1:0] | Block size of FEC codeword for BMSG frame payload | Clause 7.1.2.3.2.9.2 | +| FEC_RATE | | [4:2] | FEC coding rate for BMSG frame payload | Clause 7.1.2.3.2.9.3 | + +**Table 7-10 – BMSG PHY-frame type specific fields – core part** + +| Field | Octet | Bits | Description | Reference | +|--------------------|-----------|---------|---------------------------------------------------------------------------------------------------------|--------------------------------| +| REP | | [7:5] | Number of repetitions used for encoding the BMSG frame payload | Clause 7.1.2.3.2.9.4 | +| FCF | 3 | [2:0] | FEC concatenation factor | Clause 7.1.2.3.2.9.5 | +| SI | | [6:3] | Scrambler initialization | Clause 7.1.2.3.2.9.6 | +| MDET | | [7] | Master is detected | Clause 7.1.2.3.2.9.7 | +| BAT_ID/
BMAT_ID | 4 | [4:0] | Bit allocation table identifier/Bit allocation and Tx port mapping allocation table identifier for MIMO | Clause 7.1.2.3.2.9.8 | +| OFB_ID/GRP_ID | | [7:5] | Operational frequency band identifier/sub-carrier grouping identifier | Clause 7.1.2.3.2.9.9 | +| GI_ID | 5 | [2:0] | Guard interval identifier | Clause 7.1.2.3.2.9.10 | +| APSD_MAX-M | | [7:3] | APSD_MAX-M of a BMSG frame | Clause 7.1.2.3.2.9.11 | +| CONNECTION_ID | 6 | [7:0] | Connection identifier | Clause 7.1.2.3.2.9.12 | +| RPRQ | 7 | [1:0] | Reply required | Clause 7.1.2.3.2.9.13 | +| BRSTCnt | | [3:2] | Burst frame count | Clause 7.1.2.3.2.9.14 | +| BEF | | [4] | Burst end flag | Clause 7.1.2.3.2.9.15 | +| AIFG_IND | | [5] | AIFG indication | Clause 7.1.2.3.2.9.16 | +| MIMO_IND | | [6] | MIMO indication | Clause 7.1.2.3.2.9.25 | +| EXTACKGR | | [7] | Extended ACK granted | Clause 7.1.2.3.2.9.26 | +| ACE_SYM | 8 | [2:0] | Number of ACE symbols | Clause 7.1.2.3.2.9.17 | +| CNN_MNGMT | | [6:3] | Connection management | Clause 7.1.2.3.2.9.18 | +| APSD_MAX-M_EXT | | [7] | APSD_MAX-M Extension | Clause 7.1.2.3.2.9.28 | +| BRURQ | 9 and 10 | [15:0] | Bandwidth reservation update request | Clause 7.1.2.3.2.9.19 (Note 2) | +| START_SSN | 9 and 10 | [15:0] | Start segment sequence number | Clause 7.1.2.3.2.9.20 (Note 3) | +| CURRTS | 11 | [6:0] | Current TS | Clause 7.1.2.3.2.9.21 | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note 1) | +| Reserved | 12 and 13 | [0] | Reserved | Reserved by ITU-T (Note 1) | +| BTXGL | | [8:1] | Bidirectional transmission grant length | Clause 7.1.2.3.2.9.22 | +| BTXEF | | [9] | Bidirectional transmission end flag | Clause 7.1.2.3.2.9.23 | +| P-DACK | | [10] | Piggybacked delayed acknowledgement | Clause 7.1.2.3.2.9.27 | +| Reserved | | [15:11] | Reserved | Reserved by ITU-T (Note 1) | + +**Table 7-10 – BMSG PHY-frame type specific fields – core part** + +| Field | Octet | Bits | Description | Reference | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|-------|--------------------------------|-----------------------| +| ACK_CE_CTRL | 14 | [7:0] | ACK channel estimation control | Clause 7.1.2.3.2.9.24 | +| NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver.
NOTE 2 – The BRURQ field is defined when the START_SSN field is not defined.
NOTE 3 – The START_SSN field is defined only when CNN_MNGMT = 0001, CNN_MNGMT = 0011, CNN_MNGMT = 0101 or CNN_MNGMT = 0111. Otherwise the meaning of this field is BRURQ. | | | | | + +The PHY-frame header fields specific to the extended part of the header of the BMSG frame type are listed in Table 7-54 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.1 Duration for BMSG frame (BMSG\_DUR)** + +See clause 7.1.2.3.2.9.1 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.2 Block size (BLKSZ)** + +See clause 7.1.2.3.2.9.2 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.3 FEC coding rate (FEC\_RATE)** + +See clause 7.1.2.3.2.9.3 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.4 Repetitions (REP)** + +See clause 7.1.2.3.2.9.4 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.5 FEC concatenation factor (FCF)** + +See clause 7.1.2.3.2.9.5 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.6 Scrambler initialization (SI)** + +See clause 7.1.2.3.2.9.6 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.7 Master is detected indication (MDET)** + +See clause 7.1.2.3.2.9.7 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.8 Bit allocation table identifier / Bit and Tx port mapping allocation table for MIMO (BAT\_ID/BMAT\_ID)** + +See clause 7.1.2.3.2.2.8. + +###### **7.1.2.3.2.9.9 OFB identifier/sub-carrier grouping identifier (OFB\_ID/GRP\_ID)** + +See clause 7.1.2.3.2.2.9. + +###### **7.1.2.3.2.9.10 Guard interval identifier (GI\_ID)** + +See clause 7.1.2.3.2.9.10 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.11 Maximum Actual PSD of BMSG frame (APSD\_MAX-M)** + +See clause 7.1.2.3.2.9.11 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.12 Connection identifier (CONNECTION\_ID)** + +See clause 7.1.2.3.2.9.12 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.13 Reply required (RPRQ)** + +See clause 7.1.2.3.2.9.13 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.14 Burst frame count (BRSTCnt)** + +See clause 7.1.2.3.2.9.14 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.15 Burst end flag (BEF)** + +See clause 7.1.2.3.2.9.15 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.16 AIFG indication (AIFG\_IND)** + +See clause 7.1.2.3.2.9.16 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.17 ACE symbols (ACE\_SYM)** + +See clause 7.1.2.3.2.9.17 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.18 Connection management (CNN\_MNGMT)** + +See clause 7.1.2.3.2.9.18 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.19 Bandwidth reservation update request (BRURQ)** + +See clause 7.1.2.3.2.9.19 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.20 Start segment sequence number (START\_SSN)** + +See clause 7.1.2.3.2.9.20 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.21 Current TS (CURRTS)** + +See clause 7.1.2.3.2.9.21 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.22 Bidirectional transmission grant length (BTXGL)** + +See clause 7.1.2.3.2.9.22 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.23 Bidirectional transmission end flag (BTXEF)** + +See clause 7.1.2.3.2.9.23 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.24 ACK channel estimation control (ACK\_CE\_CTRL)** + +The interpretation of this field shall be as specified for the ACK\_CE\_CTRL field of the ACK frame in clause 7.1.2.3.2.3.1. + +###### **7.1.2.3.2.9.25 MIMO indication (MIMO\_IND)** + +See clause 7.1.2.3.2.2.24. + +###### **7.1.2.3.2.9.26 Extended ACK Granted (EXTACKGR)** + +See clause 7.1.2.3.2.9.25 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.27 Piggybacked delayed acknowledgement (P-DACK)** + +See clause 7.1.2.3.2.9.26 of [ITU-T G.9960]. + +###### **7.1.2.3.2.9.28 APSD\_MAX-M extension** + +See clause 7.1.2.3.2.9.27 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10 BACK PHY-frame type specific fields** + +Table 7-11 lists the fields specific to the core part of the PHY-frame header of the BACK frame type. + +**Table 7-11 – BACK PHY-frame type specific fields – core part** + +| Field | Octet | Bits | Description | Reference | +|----------------|----------|--------|---------------------------------------------------------------------------------------------------------|--------------------------| +| BACK_DUR | 0 and 1 | [15:0] | Duration for BACK frame | Clause 7.1.2.3.2.10.1 | +| BLKSZ | 2 | [1:0] | Block size of FEC codeword for BACK frame payload | Clause 7.1.2.3.2.10.2 | +| FEC_RATE | | [4:2] | FEC coding rate for BACK frame payload | Clause 7.1.2.3.2.10.3 | +| REP | | [7:5] | Number of repetitions used for encoding the BACK frame payload | Clause 7.1.2.3.2.10.4 | +| FCF | 3 | [2:0] | FEC concatenation factor | Clause 7.1.2.3.2.10.5 | +| SI | | [6:3] | Scrambler initialization | Clause 7.1.2.3.2.10.6 | +| MDET | | [7] | Master is detected | Clause 7.1.2.3.2.10.7 | +| BAT_ID/BMAT_ID | 4 | [4:0] | Bit allocation table identifier/Bit allocation and Tx port mapping allocation table identifier for MIMO | Clause 7.1.2.3.2.10.8 | +| OFB_ID/GRP_ID | | [7:5] | Operational frequency band identifier/sub-carrier grouping identifier | Clause 7.1.2.3.2.10.9 | +| GI_ID | 5 | [2:0] | Guard interval identifier | Clause 7.1.2.3.2.10.10 | +| APSD_MAX-M | | [7:3] | APSD_MAX-M of a BACK frame | Clause 7.1.2.3.2.10.11 | +| CONNECTION_ID | 6 | [7:0] | Connection identifier | Clause 7.1.2.3.2.10.12 | +| RPRQ | 7 | [1:0] | Reply required | Clause 7.1.2.3.2.10.13 | +| BRSTCnt | | [3:2] | Burst frame count | Clause 7.1.2.3.2.10.14 | +| BEF | | [4] | Burst end flag | Clause 7.1.2.3.2.10.15 | +| AIFG_IND | | [5] | AIFG indication | Clause 7.1.2.3.2.10.16 | +| MIMO_IND | | [6] | MIMO indication | Clause 7.1.2.3.2.10.21 | +| APSD_MAX-M_EXT | | [7] | APSD_MAX-M extension | Clause 7.1.2.3.2.10.22 | +| ACE_SYM | 8 | [2:0] | Number of ACE symbols | Clause 7.1.2.3.2.10.17 | +| CNN_MNGMT | | [6:3] | Connection management | Clause 7.1.2.3.2.10.18 | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note) | +| BTXRL | 9 | [7:0] | Bidirectional transmission request length | Clause 7.1.2.3.2.10.19 | +| ACK_CE_CTRL | 10 | [7:0] | ACK channel estimation control | Clause 7.1.2.3.2.10.20 | +| Reserved | 11 to 14 | [31:0] | Reserved | Reserved by ITU-T (Note) | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +The PHY-frame header fields specific to the extended part of the header of the BACK frame type are listed in Table 7-54 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.1 Duration for BACK frame (BACK\_DUR)** + +See clause 7.1.2.3.2.10.1 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.2 Block size (BLKSZ)** + +See clause 7.1.2.3.2.10.2 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.3 FEC coding rate (FEC\_RATE)** + +See clause 7.1.2.3.2.10.3 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.4 Repetitions (REP)** + +See clause 7.1.2.3.2.10.4 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.5 FEC concatenation factor (FCF)** + +See clause 7.1.2.3.2.10.5 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.6 Scrambler initialization (SI)** + +See clause 7.1.2.3.2.10.6 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.7 Master is detected indication (MDET)** + +See clause 7.1.2.3.2.10.7 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.8 Bit allocation table identifier / Bit and Tx port mapping allocation table for MIMO (BAT\_ID/BMAT\_ID)** + +See clause 7.1.2.3.2.2.8. + +###### **7.1.2.3.2.10.9 OFB identifier/sub-carrier grouping identifier (OFB\_ID/GRP\_ID)** + +See clause 7.1.2.3.2.2.9. + +###### **7.1.2.3.2.10.10 Guard interval identifier (GI\_ID)** + +See clause 7.1.2.3.2.10.10 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.11 Maximum Actual PSD of BACK frame (APSD\_MAX-M)** + +See clause 7.1.2.3.2.10.11 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.12 Connection identifier (CONNECTION\_ID)** + +See clause 7.1.2.3.2.10.12 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.13 Reply required (RPRQ)** + +See clause 7.1.2.3.2.10.13 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.14 Burst frame count (BRSTCnt)** + +See clause 7.1.2.3.2.10.14 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.15 Burst end flag (BEF)** + +See clause 7.1.2.3.2.10.15 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.16 AIFG indication (AIFG\_IND)** + +See clause 7.1.2.3.2.10.16 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.17 ACE symbols (ACE\_SYM)** + +See clause 7.1.2.3.2.10.17 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.18 Connection management (CNN\_MNGMT)** + +See clause 7.1.2.3.2.10.18 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.19 Bidirectional transmission request length (BTXRL)** + +See clause 7.1.2.3.2.10.19 of [ITU-T G.9960]. + +###### **7.1.2.3.2.10.20 ACK channel estimation control (ACK\_CE\_CTRL)** + +The interpretation of this field shall be as specified for the ACK\_CE\_CTRL field of the ACK frame in clause 7.1.2.3.2.3.1. + +###### **7.1.2.3.2.10.21 MIMO indication (MIMO\_IND)** + +See clause 7.1.2.3.2.2.24. + +###### **7.1.2.3.2.10.22 APSD\_MAX-M extension** + +See clause 7.1.2.3.2.10.21 of [ITU-T G.9960]. + +###### **7.1.2.3.2.11 ACTMG PHY-frame type specific fields** + +See clause 7.1.2.3.2.11 of [ITU-T G.9960]. + +###### **7.1.2.3.2.12 Reserved** + +Reserved by ITU-T. + +###### **7.1.2.3.2.13 Reserved** + +Reserved by ITU-T. + +###### **7.1.2.3.2.14 Reserved** + +Reserved by ITU-T. + +###### **7.1.2.3.2.15 Reserved** + +Reserved by ITU-T. + +###### **7.1.2.3.2.16 FTE PHY-frame type specific fields** + +See clause 7.1.2.3.2.16 of [ITU-T G.9960]. + +###### **7.1.2.3.2.17 Maximum actual PSD of MAP frame (APSD\_MAX-MAP\_LSB and APSD\_MAX-MAP\_MSB)** + +See clause 7.1.2.3.2.17 of [ITU-T G.9960]. + +##### **7.1.2.3.3 Extended header fields** + +See clause 7.1.2.3.3 of [ITU-T G.9960]. + +### **7.1.3 Physical medium attachment (PMA) sublayer** + +The functional model of the PMA is presented in Figure 7-4. It is intended to describe in more detail the PMA functional block presented in Figure 7-1. + +In the transmit direction, the incoming PHY frame (except for the preamble and the channel estimation symbols) at the $\alpha$ -reference point has a format as defined in clause 7.1.2. Both the header bits and the payload bits of the incoming frame are scrambled as described in clause 7.1.3.1. The header bits of the incoming frame are encoded as described in clause 7.1.3.4. The payload bits are + +encoded, as described in clause 7.1.3.3. The parameters of the payload encoder are controlled by the PHY management entity. + +After encoding, the payload is parsed into multiple spatial streams as described in clause 7.1.3.5. The header and payload are then each segmented into an integer number of symbol frames as described in clause 7.1.3.6. The obtained symbol frames of the header and the payload are submitted to the PMD (at the $\delta$ -reference point) for modulation and transmission over the medium. + +In the receive direction, all necessary inverse operations of payload spatial streams de-parsing, decoding and de-scrambling are performed on the received symbol frames. The recovered PHY-frame header and payload are submitted to the $\alpha$ -reference point for further processing in the PCS. + +![Functional model of PMA diagram showing TX and RX paths with various processing blocks like Scrambler, FEC encoders, and PHY management control data.](00504fc688ebcf131ccbeff94dfc9939_img.jpg) + +The diagram illustrates the functional model of the PMA (Physical Medium Attachment) for both transmission (TX) and reception (RX) directions, separated by a dashed line representing the $\delta$ -reference point. A vertical dashed line on the left marks the $\alpha$ -reference point. + +- TX Path:** A "TX PHY frame" enters from the top and passes through a "Scrambler". The output splits into two parallel blocks: "Header FEC encoder and repetition encoder" and "Payload FEC encoder and repetition encoder". Both outputs then pass through a "Spatial streams parser". The next stage is "Segmentation to OFDM symbols", which produces "TX header symbol frames" and "TX payload symbol frames" at the $\delta$ -reference point. +- RX Path:** "RX header symbol frames" and "RX payload symbol frames" enter from the bottom at the $\delta$ -reference point, passing through a "Spatial streams de-parser". The output then goes to a large block containing "De-scrambler", "Header decoder", "Payload decoder", and "Pad removal". The final output is an "RX PHY frame" at the $\alpha$ -reference point. +- PHY Management:** A vertical bar on the right represents the "PHY management" entity. It sends "PHY control data" to the "Scrambler" and the "De-scrambler/Decoder" block. +- Reference Points:** The $\alpha$ -reference point is at the top left, and the $\delta$ -reference point is a horizontal dashed line near the bottom. +- Diagram Label:** G.9963(11)\_F7-4 is located in the bottom right corner. + +Functional model of PMA diagram showing TX and RX paths with various processing blocks like Scrambler, FEC encoders, and PHY management control data. + +Figure 7-4 – Functional model of PMA + +#### 7.1.3.1 Scrambling + +See clause 7.1.3.1 of [ITU-T G.9960]. + +#### 7.1.3.2 FEC encoding + +See clause 7.1.3.2 of [ITU-T G.9960]. + +#### 7.1.3.3 Payload encoding + +See clause 7.1.3.3 of [ITU-T G.9960]. Whenever an ITU-T G.9963 node uses RCM, the payload is created as a single spatial stream, using the RCM scheme described in clause 7.1.3.3 of [ITU-T G.9960]. + +#### 7.1.3.4 Header encoding + +See clause 7.1.3.4 of [ITU-T G.9960]. The PHY-frame header shall be created as a single spatial stream. + +#### 7.1.3.5 Spatial stream parser + +The encoded payload block is the input of the spatial stream parser. Whenever the payload is to be created as two spatial streams, this block shall output the two spatial streams that will later be segmented into OFDM symbols. Whenever the payload is to be created as a single spatial stream, the encoded payload block is delivered to the output of this block as is (i.e., the stream parser is not operating in this case). + +The parsing operation shall assign bits alternatively to each stream at the sub-carrier level. Defining $b_j^{(i)}$ as the number of data bits to be loaded to the sub-carrier $j$ of spatial stream $i$ , the spatial stream parser shall: + +- Assign the first $b_0^{(1)}$ bits at its input to spatial stream 1 +- Assign the next $b_0^{(2)}$ bits at its input to spatial stream 2 +- Assign the next $b_1^{(1)}$ bits at its input to spatial stream 1 +- Assign the next $b_1^{(2)}$ bits at its input to spatial stream 2 +- And so on ... + +NOTE – If $b_j^{(i)}$ is zero, no data bits are assigned to sub-carrier $j$ of spatial stream $i$ . + +#### 7.1.3.6 Segmentation into symbol frames + +The parsed payload blocks for spatial streams 1 and 2 and the encoded header block from the output of the header encoder shall be segmented into symbol frames. The maximum number of bits in the payload symbol frame of spatial stream 1 shall not exceed the value of $k_p^{(1)}$ . In a similar way, the maximum number of bits in the payload symbol frame of spatial stream 2 shall not exceed the value of $k_p^{(2)}$ . $k_p^{(i)}$ is the total number of bits that can be loaded onto the payload OFDM symbol of spatial stream $i$ according to the current BAT of this spatial stream. The number of bits in the header symbol frame shall be $k_H$ . Payload and header symbol frames shall be passed to the PMD, as described in Figure 7-4. + +##### 7.1.3.6.1 Payload segmentation + +After parsing the encoded payload block, the set of bits assigned to spatial stream 1 and the set of bits assigned to spatial stream 2 shall each be segmented into one or more symbol frames, denoted hereafter as "symbol frames of spatial stream 1" and "symbol frames of spatial stream 2". + +In normal mode (see Figure 7-8 of [ITU-T G.9960]) and for each spatial stream, the first symbol frame of spatial stream $i$ ( $i$ , is the number of the spatial stream and is either 1 or 2) shall contain the first $k_p^{(i)}$ bits of the payload block of spatial stream $i$ . The second symbol frame of spatial stream $i$ shall contain the second $k_p^{(i)}$ bits of the payload block of spatial stream $i$ and so on, until the last symbol frame of spatial stream $i$ . If the number of bits in the last symbol frame is less than $k_p^{(i)}$ , the unloaded supported sub-carriers of the OFDM symbol for the last symbol frame shall be modulated by a pseudo-random sequence of bits, as described in clause 7.1.4.2.5. Payload segmentation is illustrated in Figure 7-5. + +In RCM the payload is created as a single spatial stream. In this case, the payload segmentation shall be as described for RCM in clause 7.1.3.5.1 of [ITU-T G.9960]. + +![Diagram of payload segmentation for spatial stream i. It shows a 'Payload block of spatial stream i' divided into segments of k_p^(i) bits. Below this, 'Symbol frame of spatial stream i' is shown, containing 'Symbol frame 1', 'Symbol frame 2', an ellipsis, 'Symbol frame N_sym-1', and 'Symbol frame N_sym'. An arrow labeled 'Unloaded sub-carriers' points to the right side of the diagram. The text 'LSB, octet 0' is at the top left, and 'G.9963(11)_F7-5' is at the bottom right.](08dce7ad4c512fdf0c0cde60415fade6_img.jpg) + +Diagram of payload segmentation for spatial stream i. It shows a 'Payload block of spatial stream i' divided into segments of k\_p^(i) bits. Below this, 'Symbol frame of spatial stream i' is shown, containing 'Symbol frame 1', 'Symbol frame 2', an ellipsis, 'Symbol frame N\_sym-1', and 'Symbol frame N\_sym'. An arrow labeled 'Unloaded sub-carriers' points to the right side of the diagram. The text 'LSB, octet 0' is at the top left, and 'G.9963(11)\_F7-5' is at the bottom right. + +**Figure 7-5 – Payload segmentation of the payload block of spatial stream $i$ ( $i = 1, 2$ )** + +##### 7.1.3.6.2 Header segmentation + +See clause 7.1.3.5.2 of [ITU-T G.9960]. + +#### 7.1.3.7 PROBE frame + +The PROBE frame is intended for the channel estimation procedure. The header of the PROBE frame shall be as defined in clause 7.1.2.3. Following the PFH, the PROBE frame may include ACE symbols as defined in clauses 7.1.4.2.4.4 (tone mapping) and 7.1.4.4.4.2 (Tx port mapping). The payload of the PROBE frame shall contain a number of probe symbols, i.e., symbol frames with no data, which can be of three types: + +- Silent symbols, which are symbols for which all sub-carriers are considered masked sub-carriers (MSCs). +- 1 SS channel estimation probe symbols, which are created as a single SS and for which all supported sub-carriers (SSCs) are considered inactive sub-carriers (ISCs) and are modulated by a pseudo-random sequence. +- 2 SS channel estimation probe symbols, which are created as two SSs and for which, for both SSs, all supported sub-carriers (SSCs) are considered inactive sub-carriers (ISCs) and are modulated by a pseudo-random sequence. + +The total number of probe symbols in each frame is indicated via the PRBSYM field in clause 7.1.2.3.2.7.1.3. + +Three PROBE frame types are identified by the PRBTYPE field as specified in clause 7.1.2.3.2.7.1.2 (Table 7-8): + +- The "Silent PROBE frame" (PRBTYPE 00002). The payload of this frame type shall be composed of silent symbols. +- The "1 SS channel estimation PROBE frame" (PRBTYPE 00012). The payload of this frame type shall be composed of channel estimation probe symbols. +- The "2 SS channel estimation PROBE frame" (PRBTYPE 10002). The payload of this frame type shall be composed of 2 SS channel estimation probe symbols followed by silent symbols (the number of silent symbols in the frame is between 0 and PRBSYM as identified by the NUM\_SILENT\_SYM field, specified in clause 7.1.2.3.2.7.2.3.3). + +These PROBE frame types can be categorized into two categories: + +- PROBE frame types which include probe symbols created as a single spatial stream (i.e., when MIMO\_IND=0). These frame types are intended for the channel estimation procedure for links with ITU-T G.9960/G.9961 nodes and links with ITU-T G.9963 nodes using a single SS (see clause 8.11). This category includes the "Silent PROBE frame" (PRBTYPE 00002) and the "1 SS channel estimation PROBE frame" (PRBTYPE 00012) PROBE frame types. The payload of these PROBE frame types includes probe symbols which can be generated in two ways: + +- When the PROBE frame is transmitted using the ITU-T G.9960 transmission, the probe symbols shall be generated as defined in clauses 7.1.4.2.5.3 of [ITU-T G.9960]. +- When the PROBE frame is transmitted using the MIMO transmission scheme (with the payload created as a single SS), the probe symbols shall be generated as defined in clauses 7.1.4.2.4.3 and 7.1.4.2.5 (tone mapping) and clause 7.1.4.4.4.3 (Tx port mapping). +- PROBE frame types which include probe symbols created as two spatial streams (i.e., when MIMO\_IND=1). These frame types are intended for the channel estimation procedure for links with ITU-T G.9963 nodes using two SSs described in clause 8.11.1. This category includes the "2 SS channel estimation PROBE frame" (PRBTTYPE 10002) PROBE frame type. The payload of this PROBE frame type may include both 2 SS channel estimation symbols and silent symbols, which are generated as defined in clauses 7.1.4.2.4.3 and 7.1.4.2.5 (tone mapping) and 7.1.4.4.4.3 (Tx port mapping). + +### 7.1.4 Physical medium dependent (PMD) sublayer + +The functional model of the PMD is presented in Figure 7-6. In the transmit direction, the tone mapper divides the incoming symbol frames (per each spatial stream) of the header and payload into groups of bits and associates each group of bits with a specific sub-carrier onto which this group shall be loaded, as specified in clause 7.1.4.2. The constellation encoder converts each incoming group of bits into a complex number that represents the constellation point for this sub-carrier. The constellation mapping process is described in clause 7.1.4.3.1. The unloaded supported sub-carriers are modulated by a pseudo-random bit sequence generated as described in clause 7.1.4.2.5. + +![Figure 7-6 – Functional model of the PMD. This block diagram illustrates the internal components and data flow of the Physical Medium Dependent (PMD) sublayer. At the top, 'Header Payload' data enters the system. In the transmit (TX) path, this data is processed through 'TX symbol frames', a 'Tone mapper', a 'Constellation mapper and scaler', a 'Constellation scrambler', 'Spatial streams', 'Tx ports mapper', and an 'OFDM modulator'. A 'Bit generator for unused sub-carriers' also feeds into the 'Constellation mapper and scaler'. A 'Preamble generation' block feeds into the 'Constellation scrambler'. The output of the OFDM modulator goes to an 'AFE' (Analog Front End) block. In the receive (RX) path, data from the AFE is processed through 'Preamble processing and carrier sense generation', a 'Demodulator', a 'MIMO decoder', and a 'Symbol frames recovery Constellation decoder', which then outputs the 'Header Payload'. A 'PHY management' block on the right is connected to the 'Preamble processing and carrier sense generation' and the 'AFE' via 'PMD control data' lines. The entire PMD sublayer is enclosed in a dashed box labeled 'δ-reference point'. Below the PMD sublayer, the 'AFE' is connected to the 'Transmission medium' via an 'MDI' (Medium Dependent Interface).](05eb72d372e4bf78e3d6a64949d77bcc_img.jpg) + +Figure 7-6 – Functional model of the PMD. This block diagram illustrates the internal components and data flow of the Physical Medium Dependent (PMD) sublayer. At the top, 'Header Payload' data enters the system. In the transmit (TX) path, this data is processed through 'TX symbol frames', a 'Tone mapper', a 'Constellation mapper and scaler', a 'Constellation scrambler', 'Spatial streams', 'Tx ports mapper', and an 'OFDM modulator'. A 'Bit generator for unused sub-carriers' also feeds into the 'Constellation mapper and scaler'. A 'Preamble generation' block feeds into the 'Constellation scrambler'. The output of the OFDM modulator goes to an 'AFE' (Analog Front End) block. In the receive (RX) path, data from the AFE is processed through 'Preamble processing and carrier sense generation', a 'Demodulator', a 'MIMO decoder', and a 'Symbol frames recovery Constellation decoder', which then outputs the 'Header Payload'. A 'PHY management' block on the right is connected to the 'Preamble processing and carrier sense generation' and the 'AFE' via 'PMD control data' lines. The entire PMD sublayer is enclosed in a dashed box labeled 'δ-reference point'. Below the PMD sublayer, the 'AFE' is connected to the 'Transmission medium' via an 'MDI' (Medium Dependent Interface). + +G.9963(15)-Amd.1(16)\_F7-6 + +Figure 7-6 – Functional model of the PMD + +The Tx port mapper, described in clause 7.1.4.4, maps the spatial streams, to transmit streams that are assigned for transmission in each of the Tx ports. Each of the OFDM modulators, described in clause 7.1.4.5, assigned to each Tx port, converts the stream of the $N$ complex numbers at its input into the stream of $N$ complex valued time-domain samples. After adding the preamble, the transmit signal of each Tx port is up-shifted by $F_{US}$ . The real part of the resultant signal assigned to each Tx port is transmitted onto the medium over a specific Tx port. Parameters of the preamble (clause 7.1.4.5) are determined by the PHY management and depend on the type of the transmitted PHY frame. + +Frames are output onto the medium with inter-frame gaps described in [ITU-T G.9961]. + +In the receive direction, the frames incoming from the medium are demodulated and decoded. The recovered symbol frames are transferred to the PMA via $\delta$ -reference point. The preamble is processed and preamble data are passed to the PHY management entity. + +#### 7.1.4.1 Sub-carrier spacing and logical indexing + +See clause 7.1.4.1 of [ITU-T G.9960]. Indexing rule #1 shall be used to relate the physical index and logical index. Indexing rule #2 shall not be used. + +#### 7.1.4.2 Tone mapper + +The tone mapper operates independently on each one of the incoming spatial streams. The tone mapper divides the incoming symbol frames of the header and payload (of each spatial stream) into groups of bits (according to the BATs and sub-carrier grouping being used for that spatial stream) and associates each group of bits with specific sub-carriers onto which these groups shall be loaded. This information, along with sub-carrier-specific gain scaling values (as described in clause 7.1.4.3.2.3 of [ITU-T G.9960]), is passed to the constellation encoder. + +##### 7.1.4.2.1 Summary of sub-carrier types + +For the purpose of tone mapping, the following types of sub-carriers are defined. + +- 1) Masked sub-carriers (MSC) are those on which transmission is not allowed, i.e., the gain on this sub-carrier shall be set to zero. Two types of MSC are defined: + - Permanently masked sub-carriers (PMSC) – those that are never allowed for transmission. The list of PMSC forms a PMSC mask, which depends on the type of medium and is defined in clause 7.2. Data bits are never mapped on PMSC. + - Regionally masked sub-carriers (RMSC) – those that are not allowed for data transmission in some regions, while may be allowed in other regions. The list of RMSC forms a RMSC mask, which depends on the type of media and on the region/application. The RMSC set consists of the sub-carriers corresponding to sub-carrier masks defined in SM descriptor and masked amateur radio bands defined in amateur radio band descriptor (see clause 8.8.5.5). The number of RMSC, $\#RMSC = \#MSC - \#PMSC$ . +- 2) Supported sub-carriers (SSC) are those on which transmission is allowed under restrictions of the relevant PSD mask. The number of SSC, $\#SSC = N - \#MSC$ . The following types of SSC are defined, per spatial stream: + - Active sub-carriers (ASC) of spatial stream $i$ (denoted $ASC^{(i)}$ , where $i = 1, 2$ ) – those that have loaded bits ( $b \geq 1$ ) for data transmission. ASC are subject to constellation point mapping, constellation scaling and constellation scrambling as described in clause 7.1.4.3. Data bits shall be mapped on ASC as described in clause 7.1.4.2.2. + - Inactive sub-carriers (ISC) of spatial stream $i$ (denoted $ISC^{(i)}$ , where $i = 1, 2$ ) – those that do not have any data bits loaded (e.g., because SNR is low). The number of ISC of spatial stream $i$ ( $i = 1, 2$ ), $\#ISC^{(i)} = \#SSC - \#ASC^{(i)}$ . ISC can be used for measurement purposes + +or other auxiliary purposes. ISC are subject to transmit power shaping. The signals transmitted on ISC are defined in clause 7.1.4.2.5. + +NOTE – Even though the MSC and SSC are the same for both spatial streams, the ASC and ISC of different spatial streams may be different. + +##### 7.1.4.2.2 Bit allocation tables (BATs) + +Tone mapping is defined by a bit allocation table (BAT) that associates sub-carrier indices with the number of bits to be loaded on the sub-carrier. This mapping is defined independently per each spatial stream. The order of sub-carrier indices in a BAT (per spatial stream) shall be in ascending order, from the smallest index to the largest index. Bits of the TX symbol frame shall be loaded on the sub-carriers in the order of indices in the BAT, according to sub-carrier indexing defined in clause 7.1.4.1. + +The BATs used by the node in the particular PHY frame, for each spatial stream, are part of the BMAT (specified in clause 7.1.4.4.3) and shall be indicated to the receiving node(s) in the BMAT\_ID field of the MSG/BMSG/BACK/PROBE PHY-frame type specific fields of the PHY-frame header, as described in clause 7.1.2.3.2.2.8. + +###### 7.1.4.2.2.1 Predefined BATs + +See clause 7.1.4.2.2.1 of [ITU-T G.9960]. + +###### 7.1.4.2.2.2 Runtime BATs + +A runtime BAT associates indices of SSCs with the number of bits to be loaded on each sub-carrier. When the payload is composed of two spatial streams and runtime BATs are used, each spatial stream is associated with its own runtime BAT. The subset of indices in the BAT associated with spatial stream $i$ with the number of loaded bits $b > 0$ identifies the $ASC^{(i)}$ (i.e., active sub-carriers of spatial stream $i$ ). In a MIMO transmission, the two BATs are selected together with the Tx port mapping allocation table (MAT), described in clause 7.1.4.4.2. This combination is called the BMAT (bit and Tx port mapping allocation table) and is described in clause 7.1.4.4.3. + +The number of bits loaded on any sub-carrier shall not exceed the maximum number of bits allowed (see clause 7.1.4.3). The number of bits shall also meet the bit loading capabilities of the communicating nodes, as advertised by them prior to communication. + +##### 7.1.4.2.3 BATs with sub-carrier grouping + +A node shall be capable of defining runtime BATs using sub-carrier grouping of $G = 1$ (no grouping), 2, 4, 8 and 16 sub-carriers with subsequent frequencies. The grouping, $G$ , applies to both spatial streams (i.e., both spatial streams use the same grouping). The default value of $G$ is 1. If grouping is used ( $G > 1$ ), all sub-carriers of the same group shall use the same bit loading. However, the bit loading for that group for different spatial streams may be different). The first group shall include $G$ sub-carriers in ascending order of sub-carrier indices defined in clause 7.1.4.1. If a group includes sub-carriers that are masked (e.g., MSC) or extends beyond the applicable sub-carrier set, the node shall apply the bit loading assigned for this group only to the applicable sub-carrier set. + +The group index $G$ shall be indicated when BATs are communicated (see clause 8.11). + +##### 7.1.4.2.4 Special mappings + +###### 7.1.4.2.4.1 Tone mapping for PHY-frame header + +See clause 7.1.4.2.5.1 of [ITU-T G.9960]. + +###### 7.1.4.2.4.2 Tone mapping for RCM + +See clause 7.1.4.2.5.2 of [ITU-T G.9960]. + +###### 7.1.4.2.4.3 Tone mapping for probe symbols + +The 1 SS channel estimation probe symbols shall be created as a single SS and modulated using a uniform loading of 2 bits per sub-carrier on the entire SSC set. For these symbols, the ISC set shall be equal to the SSC set. All ISC sub-carriers shall be modulated by a pseudo-random sequence of bits, as described in clause 7.1.4.2.5. + +The 2 SS channel estimation probe symbols shall be created as two SSs and modulated using a uniform loading of 2 bits per sub-carrier on the entire SSC set of each SS. For these symbols, the ISC set shall be equal to the SSC set. All ISC sub-carriers shall be modulated by a pseudo-random sequence of bits, as described in clause 7.1.4.2.5 + +For silent symbols, all sub-carriers shall be considered as MSCs (masked sub-carriers). + +###### 7.1.4.2.4.4 Tone mapping for ACE symbols + +The ACE symbol shall be modulated using a uniform loading of 2 bits per sub-carrier on the entire SSC set. ACE symbols shall be created as a single spatial stream. For the ACE, the ISC set shall be equal to the SSC set. All ISC sub-carriers shall be modulated by a pseudo-random sequence of bits, as described in clause 7.1.4.2.5. + +##### 7.1.4.2.5 Modulation of unloaded supported sub-carriers + +Supported sub-carriers (SSC) that are not loaded with encoded payload bits or that are partially loaded with encoded payload bits for spatial stream $i$ ( $i = 1, 2$ ) – that is, $ISC^{(i)}$ and unloaded or partially loaded $ASC^{(i)}$ (herein referred to as unloaded SSCs of spatial stream $i$ , $USSC^{(i)}$ ) – shall be loaded with a pseudo-random sequence defined by the linear feedback shift register (LFSR) generator with the polynomial $p(x) = x^{23} + x^{18} + 1$ shown in Figure 7-7. The LFSR shall operate on the sub-carriers of each spatial stream separately. In other words, the LFSR shall be initialized differently for each spatial stream as described hereafter and shall produce bits to load the sub-carriers of each spatial stream separately. The LFSR generator shall be initialized at the beginning of each OFDM symbol with a DM-generated seed received during registration of the node into the domain through the UnloadedSubcarrierInitialSeedStream1 and UnloadedSubcarrierInitialSeedStream2 fields of the additional MIMO domain information auxiliary information sub-field (see clause 8.8.7) for spatial streams 1 and 2, respectively. The $i$ -th payload symbol shall use the seed $S_k$ where $k$ is equal to $(i - 1, \text{ modulo } 64) + 1$ , where $i = 1, 2, 3, 4, \dots$ . $S_k$ is generated by advancing the LFSR by $8192 * (k - 1)$ from the original DM-generated seed. An example of LFSR seeds for an initial seed of $7\text{FFFFF}_{16}$ (stream 1) and $7\text{FFFFC}_{16}$ (spatial stream 2) is provided in Tables 7-14 and 7-15. + +NOTE – Seeds $S_1$ to $S_{64}$ are used to initialize the LFSR for payload symbols 1-64, 65-128 and so on. The LSB of the seed $S_k$ corresponds to $c_1$ . + +The DM-generated seeds shall be chosen among the pool of allowed seeds described in Tables 7-12 and 7-13, depending on the value of the domain identifier (DOD) of the domain and the spatial stream. + +**Table 7-12 – Pool of allowed DM-generated seeds for unloaded supported sub-carriers LFSR generator for spatial stream 1** + +| DOD | Allowed seeds | +|-----|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | $7\text{FFFFF}_{16}$ ; $003\text{FE0}_{16}$ ; $7\text{FC060}_{16}$ ; $7803\text{F9}_{16}$ ; $0\text{FF813}_{16}$ ; $7\text{EFE80}_{16}$ ; $01\text{FCF}_{16}$ ; $40202\text{F}_{16}$ ; $038638_{16}$ | +| 1 | $7\text{FFFFF}_{16}$ ; $7\text{DC2E0}_{16}$ ; $70874\text{D}_{16}$ ; $401\text{FB7}_{16}$ ; $61\text{F327}_{16}$ ; $0\text{F78B3}_{16}$ ; $3\text{FDFD7}_{16}$ ; $0\text{DC513}_{16}$ ; $1\text{E73E7}_{16}$ | +| 2 | $7\text{FFFFF}_{16}$ ; $1\text{EB138}_{16}$ ; $731\text{F9B}_{16}$ ; $057\text{B41}_{16}$ ; $4\text{DE53C}_{16}$ ; $7099\text{A3}_{16}$ ; $0080\text{A6}_{16}$ ; $07\text{BC5A}_{16}$ ; $0399\text{C8}_{16}$ | +| 3 | $7\text{FFFFF}_{16}$ ; $3027\text{C4}_{16}$ ; $1\text{F8F1B}_{16}$ ; $30\text{A762}_{16}$ ; $1\text{D8A1F}_{16}$ ; $6\text{FB79B}_{16}$ ; $6\text{E3675}_{16}$ ; $78\text{B9A1}_{16}$ ; $65\text{F92E}_{16}$ | +| 4 | $7\text{FFFFF}_{16}$ ; $5\text{EED10}_{16}$ ; $7\text{F3F09}_{16}$ ; $16\text{E6B5}_{16}$ ; $5\text{FD0FF}_{16}$ ; $1\text{EB13C}_{16}$ ; $6\text{B8DD5}_{16}$ ; $7795\text{D2}_{16}$ ; $3\text{D222E}_{16}$ | +| 5 | $7\text{FFFFF}_{16}$ ; $0174\text{B0}_{16}$ ; $79903\text{D}_{16}$ ; $604\text{F7B}_{16}$ ; $38638\text{D}_{16}$ ; $698\text{A2D}_{16}$ ; $7\text{CE688}_{16}$ ; $50281\text{F}_{16}$ ; $48\text{E4C4}_{16}$ | + +**Table 7-12 – Pool of allowed DM-generated seeds for unloaded supported sub-carriers LFSR generator for spatial stream 1** + +| DOD | Allowed seeds | +|-----|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 6 | 7FFFFF 16 ; 7ABE59 16 ; 785321 16 ; 26D2B1 16 ; 0207F8 16 ; 0B6CAA 16 ; 306764 16 ; 096B52 16 ; 12757B 16 | +| 7 | 7FFFFF 16 ; 734122 16 ; 1D29EE 16 ; 4D67BC 16 ; 073961 16 ; 763502 16 ; 7C58CE 16 ; 7B4816 16 ; 5E6F90 16 | +| 8 | 7FFFFF 16 ; 0AFC72 16 ; 198299 16 ; 5AABBE 16 ; 1E8EDC 16 ; 618E01 16 ; 6E289F 16 ; 5B22F8 16 ; 416B07 16 | +| 9 | 7FFFFF 16 ; 771574 16 ; 779791 16 ; 5D54B7 16 ; 479BCE 16 ; 1EBBF8 16 ; 09EBF4 16 ; 6926AD 16 ; 3B5461 16 | +| 10 | 7FFFFF 16 ; 06764F 16 ; 2EC96F 16 ; 3BFA45 16 ; 316B09 16 ; 6876D1 16 ; 7FEF7B 16 ; 0ABF31 16 ; 600E3B 16 | +| 11 | 7FFFFF 16 ; 5295BF 16 ; 3C064C 16 ; 48FB34 16 ; 272E4D 16 ; 32203C 16 ; 478CF6 16 ; 7330FC 16 ; 098416 16 | +| 12 | 7FFFFF 16 ; 40E0C4 16 ; 6A49F1 16 ; 620823 16 ; 44153E 16 ; 3BD438 16 ; 0878EA 16 ; 57EB86 16 ; 3DA277 16 | +| 13 | 7FFFFF 16 ; 12CF23 16 ; 730171 16 ; 164544 16 ; 1AB7C9 16 ; 74191A 16 ; 33A4AA 16 ; 68843A 16 ; 3CC639 16 | +| 14 | 7FFFFF 16 ; 1A6FB3 16 ; 068AF6 16 ; 79DC09 16 ; 2E8D44 16 ; 0733A1 16 ; 24E0D0 16 ; 3F4001 16 ; 1D56D2 16 | +| 15 | 7FFFFF 16 ; 68BC83 16 ; 612F91 16 ; 6E76A9 16 ; 51F4FC 16 ; 2B2C4D 16 ; 2C2B62 16 ; 05A54A 16 ; 28476E 16 | + +**Table 7-13 – Pool of allowed DM-generated seeds for unloaded supported sub-carriers LFSR generator for spatial stream 2** + +| DOD | Allowed Seeds | +|-----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0 | 7FFFFC 16 ; 23AA37 16 ; 7DEB20 16 ; 0E7807 16 ; 422436 16 ; 300E1C 16 ; 605098 16 ; 7FF53C 16 ; 0862AD 16 ; | +| 1 | 7FFFFC 16 ; 18BC69 16 ; 09ABAB 16 ; 07F1C5 16 ; 09E865 16 ; 2DFE39 16 ; 718D3B 16 ; 78861D 16 ; 6F8AD8 16 ; | +| 2 | 7FFFFC 16 ; 575445 16 ; 02C263 16 ; 1A717B 16 ; 40DCAB 16 ; 48F445 16 ; 65B11B 16 ; 4A639A 16 ; 411C38 16 ; | +| 3 | 7FFFFC 16 ; 35F937 16 ; 718D5C 16 ; 65F51E 16 ; 361B92 16 ; 121AD0 16 ; 2D4A2F 16 ; 1A4B85 16 ; 663275 16 ; | +| 4 | 7FFFFC 16 ; 2B63B6 16 ; 50C875 16 ; 57D522 16 ; 37E76E 16 ; 22E7A0 16 ; 6BC6D9 16 ; 638DB4 16 ; 577E3A 16 ; | +| 5 | 7FFFFC 16 ; 1E2A46 16 ; 28F7F3 16 ; 1597A0 16 ; 30FEA3 16 ; 7B6B6F 16 ; 5C5971 16 ; 733A55 16 ; 676D31 16 ; | +| 6 | 7FFFFC 16 ; 5979CF 16 ; 36D313 16 ; 47AD56 16 ; 5A00C9 16 ; 4636C2 16 ; 6D49B2 16 ; 4282E1 16 ; 1B35FF 16 ; | +| 7 | 7FFFFC 16 ; 4DBB71 16 ; 21C06E 16 ; 187B99 16 ; 3CE540 16 ; 49CED1 16 ; 43C4F6 16 ; 1CED71 16 ; 7CC353 16 ; | +| 8 | 7FFFFC 16 ; 56B9EE 16 ; 6DC0FF 16 ; 1143BD 16 ; 6DA9B9 16 ; 3D1B0B 16 ; 3C8027 16 ; 6878D1 16 ; 796EE2 16 ; | +| 9 | 7FFFFC 16 ; 5730B7 16 ; 07A508 16 ; 5C950A 16 ; 5AC4D5 16 ; 332E0B 16 ; 04B478 16 ; 068575 16 ; 276853 16 ; | +| 10 | 7FFFFC 16 ; 32BC04 16 ; 718EAA 16 ; 2D7E9F 16 ; 348B03 16 ; 7FFD87 16 ; 0CD6D5 16 ; 411EBB 16 ; 3FD43A 16 ; | +| 11 | 7FFFFC 16 ; 4225A7 16 ; 782501 16 ; 33C567 16 ; 337AC6 16 ; 07C3D0 16 ; 7615E2 16 ; 053D21 16 ; 1E0459 16 ; | +| 12 | 7FFFFC 16 ; 2C72B3 16 ; 161AE5 16 ; 495760 16 ; 11EE60 16 ; 5F4D85 16 ; 156B20 16 ; 42F91A 16 ; 78D261 16 ; | +| 13 | 7FFFFC 16 ; 753D0D 16 ; 2F8603 16 ; 29751B 16 ; 29DE16 16 ; 26AC1C 16 ; 3193F4 16 ; 1C5B5D 16 ; 0D3447 16 ; | +| 14 | 7FFFFC 16 ; 34D324 16 ; 7586CA 16 ; 6F43D9 16 ; 77FB03 16 ; 1170EA 16 ; 5D9297 16 ; 249A77 16 ; 1A76ED 16 ; | +| 15 | 7FFFFC 16 ; 127C77 16 ; 532AD6 16 ; 5ED02D 16 ; 40C4AC 16 ; 3CA7A7 16 ; 589E59 16 ; 41C05B 16 ; 0881D6 16 ; | + +The first allowed value for each spatial stream is common for all DODs and is called the default seed for unloaded supported sub-carrier LFSR generators for that spatial stream. The tuple composed of the two default seeds is called the default value for MIMO unloaded supported sub-carrier LFSR generators. + +The LFSR, for each spatial stream $i$ , shall be advanced by two bits for each sub-carrier (for both SSC and MSC) of each symbol of the payload. The two LFSR bits corresponding to the sub-carrier index 0, of each spatial stream, are $(c_1, c_2)$ of the initialization seed. The two LFSR bits corresponding to the sub-carrier index 1, of each spatial stream, are $(c_1, c_2)$ after two shifts and so on. For modulation of unloaded sub-carriers, ACE symbols shall be treated in the same manner as payload symbols with + +one difference compared to other payload symbols: ACE symbols are created as a single spatial stream, rather than two spatial streams. This means that only the LFSR operating on spatial stream 1 shall operate on the ACE symbols. + +![Diagram of an LFSR for modulation of unloaded and partially loaded sub-carriers. The diagram shows a sequence of sub-carriers C1, C2, ..., C16, C17, C18, C19, C20, C21, C22, C23. The first two sub-carriers C1 and C2 are followed by a gap (indicated by a dashed line) and then C16 through C23. Above the sub-carriers, a feedback loop labeled 'Lower m bits used for padding' connects the output of C23 through an XOR gate (+) back to the input of C1. Below the sub-carriers, an 'Initialization: (First payload symbol)' row shows the initial values: 1, 1, ..., 1, 1, 1, 1, 1, 1, 1, 1. Arrows point from this initialization row to each sub-carrier C1 through C23. The diagram is labeled G.9963(11)_F7-7.](cc72b4769f15fe33763025416c1e274d_img.jpg) + +Diagram of an LFSR for modulation of unloaded and partially loaded sub-carriers. The diagram shows a sequence of sub-carriers C1, C2, ..., C16, C17, C18, C19, C20, C21, C22, C23. The first two sub-carriers C1 and C2 are followed by a gap (indicated by a dashed line) and then C16 through C23. Above the sub-carriers, a feedback loop labeled 'Lower m bits used for padding' connects the output of C23 through an XOR gate (+) back to the input of C1. Below the sub-carriers, an 'Initialization: (First payload symbol)' row shows the initial values: 1, 1, ..., 1, 1, 1, 1, 1, 1, 1, 1. Arrows point from this initialization row to each sub-carrier C1 through C23. The diagram is labeled G.9963(11)\_F7-7. + +**Figure 7-7 – LFSR for modulation of unloaded and partially loaded sub-carriers for each of the two spatial streams** + +**Table 7-14 – Example LFSR seeds for an initial DM-generated seed of 7FFFFF16 for spatial stream 1** + +| Seed index $k$ | Seed ( $S_k$ ) | +|----------------|----------------------| +| 1 | 7FFFFF 16 | +| 2 | 26B489 16 | +| 3 | 278A91 16 | +| 4 | 15F4ED 16 | +| 5 | 5B4CB1 16 | +| 6 | 2F021F 16 | +| 7 | 7A64C1 16 | +| 8 | 414CD7 16 | +| 9 | 649D5E 16 | +| 10 | 134826 16 | +| 11 | 2A3DFC 16 | +| 12 | 2B9570 16 | +| 13 | 3C6777 16 | +| 14 | 757986 16 | +| 15 | 103962 16 | +| 16 | 0DB87B 16 | +| 17 | 076287 16 | +| 18 | 3E1A31 16 | +| 19 | 05DE6D 16 | +| 20 | 5C5B4E 16 | +| 21 | 596413 16 | +| 22 | 0613D9 16 | +| 23 | 19504A 16 | +| 24 | 50FDE0 16 | +| 25 | 5CD048 16 | +| 26 | 66C646 16 | + +**Table 7-14 – Example LFSR seeds for an initial DM-generated seed +of 7FFFF16 for spatial stream 1** + +| Seed index k | Seed ( Sk ) | +|---------------------|-------------------------------| +| 27 | 7169B3 16 | +| 28 | 480497 16 | +| 29 | 053FE3 16 | +| 30 | 51F1B1 16 | +| 31 | 7D2BA0 16 | +| 32 | 11E4D8 16 | +| 33 | 037144 16 | +| 34 | 278587 16 | +| 35 | 2CF7F7 16 | +| 36 | 027D46 16 | +| 37 | 70A7EB 16 | +| 38 | 4C622C 16 | +| 39 | 54DC68 16 | +| 40 | 01715E 16 | +| 41 | 274A7B 16 | +| 42 | 55238D 16 | +| 43 | 008B06 16 | +| 44 | 3FA255 16 | +| 45 | 777A6A 16 | +| 46 | 5154DD 16 | +| 47 | 55C203 16 | +| 48 | 0D21F9 16 | +| 49 | 1BEDE6 16 | +| 50 | 608D6B 16 | +| 51 | 4B75D3 16 | +| 52 | 22BA64 16 | +| 53 | 7D0646 16 | +| 54 | 7F56E6 16 | +| 55 | 614333 16 | +| 56 | 4F1368 16 | +| 57 | 7359EF 16 | +| 58 | 2D86A9 16 | +| 59 | 25373D 16 | +| 60 | 258466 16 | +| 61 | 4CE92A 16 | +| 62 | 6B7E3D 16 | +| 63 | 760B34 16 | +| 64 | 761EA6 16 | + +**Table 7-15 – Example LFSR seeds for an initial DM-generated seed +of 7FFFFC16 for spatial stream 2** + +| Seed index k | Seed (S k ) | +|--------------|------------------------| +| 1 | 7FFFFC 16 | +| 2 | 1AD227 16 | +| 3 | 1E2A46 16 | +| 4 | 57D3B5 16 | +| 5 | 6D32C5 16 | +| 6 | 3C087E 16 | +| 7 | 699305 16 | +| 8 | 05335F 16 | +| 9 | 12757B 16 | +| 10 | 4D209B 16 | +| 11 | 28F7F3 16 | +| 12 | 2E55C2 16 | +| 13 | 719DDD 16 | +| 14 | 55E61A 16 | +| 15 | 40E588 16 | +| 16 | 36E1ED 16 | +| 17 | 1D8A1F 16 | +| 18 | 7868C7 16 | +| 19 | 1779B5 16 | +| 20 | 716D3A 16 | +| 21 | 65904F 16 | +| 22 | 184F66 16 | +| 23 | 654129 16 | +| 24 | 43F782 16 | +| 25 | 734122 16 | +| 26 | 1B1919 16 | +| 27 | 45A6CE 16 | +| 28 | 20125E 16 | +| 29 | 14FF8D 16 | +| 30 | 47C6C7 16 | +| 31 | 74AE82 16 | +| 32 | 479361 16 | +| 33 | 0DC513 16 | +| 34 | 1E161E 16 | +| 35 | 33DFDD 16 | +| 36 | 09F51A 16 | +| 37 | 429FAF 16 | + +**Table 7-15 – Example LFSR seeds for an initial DM-generated seed of 7FFFFC16 for spatial stream 2** + +| Seed index k | Seed (S k ) | +|--------------|------------------------| +| 38 | 3188B2 16 | +| 39 | 5371A2 16 | +| 40 | 05C579 16 | +| 41 | 1D29EE 16 | +| 42 | 548E37 16 | +| 43 | 022C18 16 | +| 44 | 7E8956 16 | +| 45 | 5DE9A8 16 | +| 46 | 455377 16 | +| 47 | 57080F 16 | +| 48 | 3487E5 16 | +| 49 | 6FB79B 16 | +| 50 | 0235AF 16 | +| 51 | 2DD74D 16 | +| 52 | 0AE993 16 | +| 53 | 74191A 16 | +| 54 | 7D5B98 16 | +| 55 | 050CCE 16 | +| 56 | 3C4DA1 16 | +| 57 | 4D67BC 16 | +| 58 | 361AA4 16 | +| 59 | 14DCF4 16 | +| 60 | 161198 16 | +| 61 | 33A4AA 16 | +| 62 | 2DF8F4 16 | +| 63 | 582CD1 16 | +| 64 | 587A99 16 | + +For each spatial stream *i*, the modulation of sub-carriers that are not loaded with encoded payload bits shall be as follows: + +- 1) Starting at the beginning of the first payload OFDM symbol, each sub-carrier from the ISC(i) set (i.e., inactive sub-carriers of spatial stream *i*, *i* = 1,2) shall be modulated with two bits which are the LSBs of the LFSR, *c*1 and *c*2 using 2-bits constellation mapping defined in clause 7.1.4.3.1 (*c*1 is transmitted first). +- 2) In every OFDM symbol of payload, if the number of bits of spatial stream *i*, in the symbol frame does not fill the entire symbol, the bits from the LFSR shall be used to fill the remainder of the symbol frame of that spatial stream *i*, by taking groups of *m*(i) LSBs of the LFSR (bits *c*1 to *c**m*(i) of the LFSR, *c*1 is transmitted first) and mapping them onto the remaining sub-carriers, where *m*(i) is the number of bits allocated for a sub-carrier of spatial stream *i* as defined by the BAT of this spatial stream. For the first padded sub-carrier of spatial stream *i*, + +if $n^{(i)}$ bits of the $m^{(i)}$ loaded bits are data bits ( $n^{(i)} < m^{(i)}$ ), these $n^{(i)}$ data bits shall be loaded as the LSBs of the group of bits mapped on the constellation point and the $m^{(i)} - n^{(i)}$ bits of the LFSR (bits $c_1$ to $c_{m^{(i)}-n^{(i)}}$ of the LFSR, $c_1$ is transmitted first) shall be used as the MSBs of the group of bits mapped on the constellation point starting from LSB of LFSR. + +- 3) In the case of either the 1 SS channel estimation probe symbols or the 2 SS channel estimation probe symbols, starting at the beginning of the first payload OFDM symbol, each sub-carrier from the ISC(i) set (i.e., inactive sub-carriers of spatial stream $i$ , $i = 1, 2$ ) shall be modulated with two bits, which are the LSBs of the LFSR, $c_1$ and $c_2$ , using 2-bit constellation mapping defined in clause 7.1.4.3.1 ( $c_1$ is transmitted first). + +For each spatial stream $i$ , bits from the LFSR are loaded on sub-carriers in the order of logical indices (i.e., in the same way as data is loaded over payload symbols), according to sub-carrier indexing defined in clause 7.1.4.1. Modulation of unloaded sub-carriers shall start from the unloaded SSC of spatial stream $i$ , USSC(i), with the lowest logical index of the first payload symbol, continue in ascending order of logical indices till the unloaded SSC of spatial stream $i$ , USSC(i), with the highest logical index of the first payload symbol, continue with the unloaded SSC of spatial stream $i$ , USSC(i), with the lowest logical index of the second payload symbol, continue in ascending order of logical indices till the unloaded SSC of spatial stream $i$ , USSC(i), with the highest logical index of the second payload symbol and continue till the unloaded SSC of spatial stream $i$ , USSC(i), with the highest logical index of the last payload symbol. + +The ASCs of each spatial stream $i$ , ASC(i), from the SSC set are loaded according to the corresponding BAT of spatial stream $i$ as defined in clause 7.1.4.2.2. + +#### 7.1.4.3 Constellation encoder + +##### 7.1.4.3.1 Constellation mapping + +Constellation mapping is performed independently on each spatial stream. Constellation mapping associates every group of bits loaded onto a sub-carrier of a specific spatial stream, with the values of $I$ (in-phase component) and $Q$ (quadrature-phase component) of a constellation diagram. Each incoming group of $b$ bits $\{d_{b-1}, d_{b-2}, \dots, d_0\}$ shall be associated with a specific value of $I$ and $Q$ computed as described in this section. + +Each group of bits $\{d_{b-1}, d_{b-2}, \dots, d_0\}$ shall be mapped onto the constellation mapper with the LSB bit, $d_0$ , first. + +###### 7.1.4.3.1.1 Constellations for even number of bits + +See clause 7.1.4.3.1.1 of [ITU-T G.9960]. + +###### 7.1.4.3.1.2 Constellations for odd number of bits + +See clause 7.1.4.3.1.2 of [ITU-T G.9960]. + +##### 7.1.4.3.2 Constellation point scaling + +See clause 7.1.4.3.2 of [ITU-T G.9960]. + +##### 7.1.4.3.3 Constellation scrambler + +The phase of constellation points generated by the constellation mapper shall be shifted in accordance with the pseudo-random sequence generated by a linear feedback shift register (LFSR) generator, as shown in Figure 7-8. + +![Diagram of a Constellation scrambler showing an LFSR generator with 13 bits (s1 to s13). The first two bits, s1 and s2, are used to determine the phase shift. The LFSR is initialized with a seed of all 1s. Feedback is taken from bits s8, s11, and s12, combined via XOR gates, and the result is fed back to the input of the LFSR.](cbb2d311b20781a595488445ded48d0a_img.jpg) + +G.9963(11)\_F7-8 + +Diagram of a Constellation scrambler showing an LFSR generator with 13 bits (s1 to s13). The first two bits, s1 and s2, are used to determine the phase shift. The LFSR is initialized with a seed of all 1s. Feedback is taken from bits s8, s11, and s12, combined via XOR gates, and the result is fed back to the input of the LFSR. + +**Figure 7-8 – Constellation scrambler** + +The LFSR generator shall implement the polynomial $g(x) = x^{13} + x^{12} + x^{11} + x^8 + 1$ . + +The LFSR shall be advanced by 2 bits for each sub-carrier. For the header, ACE and payload, bits shall be assigned to sub-carriers of spatial streams in the following order: + +- Starting from the sub-carrier with the lowest logical index, the following shall be performed: + - The two LSBs, s1 and s2, of the register shall be taken to determine the phase shift applied to the constellation point of spatial stream 1 associated with this sub-carrier, according to Table 7-16. + - If the symbol comprises two spatial streams, the same two bits, s1 and s2, shall be used to determine the phase shift applied to the constellation point of spatial stream 2 associated with this sub-carrier, according to Table 7-16; otherwise this step shall be skipped. + - The LFSR shall then be advanced by two bits. +- Continue to the next sub-carrier in order of logical index (see clause 7.1.4.1). For this sub-carrier the same operations described in the previous bullet shall be performed. +- Continue till the sub-carrier with the highest logical index. Again, for this sub-carrier the same operations described in the previous bullet shall be performed. + +**Table 7-16 – Constellation phase shift versus LFSR output** + +| LFSR output | | Phase shift (rad) | +|-------------|----|-------------------| +| s2 | s1 | | +| 0 | 0 | 0 | +| 0 | 1 | $\pi/2$ | +| 1 | 0 | $\pi$ | +| 1 | 1 | $3\pi/2$ | + +For header, ACE and payload, the shift of the LFSR for sub-carrier index $i$ shall be $2i$ (for both SSC and MSC). Two LFSR bits corresponding to the sub-carrier index 0 are (s1, s2) of the initialization seed. Two LFSR bits corresponding to the sub-carrier index 1 are (s1, s2) after two shifts and so on. + +For preamble, INUSE, PR, NACK and IDPS signals, the shift of the LFSR for sub-carrier index $(i \times k_m)$ shall be $2i$ where $k_m$ denotes the sub-carrier spacing multiplier for preamble section $m$ (see clause 7.1.4.6.3). + +The LFSR generator shall be initialized with the seed $1FFF_{16}$ for each OFDM symbol. The LSB of the seed corresponds to $s_1$ . The constellation scrambling shall be applied to the PHY-frame header, ACE and all payload symbols by rotating the originally mapped constellation point $Z_{i,l}^0$ by the phase shift $\theta$ to obtain the complex value for the $Z_{i,l}$ for input to the IDFT (see clause 7.1.4.5.1). + +$$Z_{i,l} = Z_{i,l}^0 \cdot \exp(j\theta).$$ + +#### 7.1.4.4 Tx port mapper + +The Tx port mapper inputs are the spatial streams at the outputs of the constellation encoder. The outputs are the transmit streams which are transformed to time-domain samples by the OFDM modulator and connected to Tx ports. The Tx port mapper operates on a per sub-carrier basis. It maps pairs of constellation points assigned to the two spatial streams on the same sub-carrier, to modified pair of signals which are connected (after OFDM modulation, i.e., IDFT) to Tx ports, according to a Tx port mapping allocation table (MAT). The operation of the Tx port mapper is described hereafter. + +Let us denote: + +$S_{in,i}^{(j)}$ – the input signal point, associated with sub-carrier $i$ ( $i = 0, \dots, N-1$ ), of spatial stream $j$ ( $j = 1, 2$ ) + +$S_{out,i}^{(k)}$ – the output signal point, associated with sub-carrier $i$ ( $i = 0, \dots, N-1$ ), of transmit stream $k$ ( $k = 1, 2$ ) + +In cases where only a single spatial stream is used, $S_{in,i}^{(2)} = 0$ . + +The "Tx port mapping matrix" for sub-carrier $i$ is denoted: + +$$TPM_i = \begin{bmatrix} TPM_{11,i} & TPM_{12,i} \\ TPM_{21,i} & TPM_{22,i} \end{bmatrix}, i = 0, \dots, N-1,$$ + +where $TPM_{k,j,i}$ denotes the mapping from spatial stream $j$ to transmit stream $k$ for sub-carrier $i$ . + +The Tx port mapping operation, per sub-carrier $i$ , shall be performed according to the following: + +$$\begin{bmatrix} S_{out,i}^{(1)} \\ S_{out,i}^{(2)} \end{bmatrix} = \begin{bmatrix} TPM_{11,i} & TPM_{12,i} \\ TPM_{21,i} & TPM_{22,i} \end{bmatrix} \cdot \begin{bmatrix} S_{in,i}^{(1)} \\ S_{in,i}^{(2)} \end{bmatrix}, i = 0, \dots, N-1$$ + +The specific mapping is described by specific mapping matrices, defined in clause 7.1.4.4.1 and the MAT, as defined in clause 7.1.4.4.2. + +Mapping of Tx port (i.e., transmit stream) to an actual combination of conductors (e.g., In the powerline case, Tx port 1 connects to P-N terminal) is vendor discretionary. However, this mapping shall not change once a node is registered to a domain. + +##### 7.1.4.4.1 Specific Tx port mapping matrices + +###### 7.1.4.4.1.1 The "direct" mapping, $TPM \#0$ + +The matrix for the "direct" Tx port mapping for two spatial streams shall be the identity matrix: + +$$TPM \#0 = \frac{1}{\sqrt{2}} \begin{bmatrix} 1 & 0 \\ 0 & 1 \end{bmatrix}$$ + +###### 7.1.4.4.1.2 The "duplication" mapping, $TPM \#1$ + +The matrix for the "duplication" Tx port mapping for a single spatial stream shall be: + +$$TPM \#1 = \frac{1}{\sqrt{2}} \begin{bmatrix} 1 & 0 \\ 1 & 0 \end{bmatrix}$$ + +###### 7.1.4.4.1.3 The "duplicate and negate" mapping, *TPM #2* + +The matrix for the "duplicate and negate" Tx port mapping for a single spatial stream shall be: + +$$TPM \#2 = \frac{1}{\sqrt{2}} \begin{bmatrix} 1 & 0 \\ -1 & 0 \end{bmatrix}$$ + +###### 7.1.4.4.1.4 The "Tx port 1" mapping, *TPM #3* + +The matrix for the "Tx port 1" Tx port mapping for two spatial streams shall be: + +$$TPM \#3 = \begin{bmatrix} 1 & 0 \\ 0 & 0 \end{bmatrix}$$ + +###### 7.1.4.4.1.5 The "Tx port 2" mapping, *TPM #4* + +The matrix for the "Tx port 2" Tx port mapping for two spatial streams shall be: + +$$TPM \#4 = \begin{bmatrix} 0 & 0 \\ 0 & 1 \end{bmatrix}$$ + +###### 7.1.4.4.1.6 The "precoding" mapping, *TPM #5* + +The matrix for the "precoding" Tx port mapping for two spatial streams is defined by the angles $\theta$ and $\varphi$ , $0 \leq \theta \leq \pi/2$ ; $0 \leq \varphi < 2\pi$ . This matrix shall be: + +$$TPM \#5 = \frac{1}{\sqrt{2}} \begin{bmatrix} e^{j\varphi} \cos \theta & -e^{j\varphi} \sin \theta \\ \sin \theta & \cos \theta \end{bmatrix}; \quad 0 \leq \theta \leq \frac{\pi}{2}; \quad 0 \leq \varphi < 2\pi$$ + +The angles $\theta$ and $\varphi$ are quantized to $B_1$ and $B_2$ bits, respectively. These values are either $B_1 = B_2 = 4$ bit or $B_1 = B_2 = 8$ bit, as described in clauses 8.11.1.7.3 and 8.11.1.7.5. The communication of the angle indices is described in clause 8.11. Given phase indices $P_1$ and $P_2$ for $\theta$ and $\varphi$ , respectively, $0 \leq P_1 \leq 2^{B_1} - 1$ ; $0 \leq P_2 \leq 2^{B_2} - 1$ , for some sub-carrier, the transmitter shall use the Tx port mapping *TPM#5*, in which: + +$$\theta = \frac{\pi \cdot (2P_1 + 1)}{2^{B_1+2}} \text{ and } \varphi = \frac{\pi \cdot (2P_2 + 1)}{2^{B_2}}.$$ + +NOTE – The transmitter EVM requirements need to be taken into account when regenerating the precoding mapping matrix in the transmitter. + +###### 7.1.4.4.1.7 The "precoding without SS 2 input" mapping, *TPM #6* + +The matrix for the "precoding without SS 2 input" Tx port mapping for two spatial streams is defined by the angles $\theta$ and $\varphi$ , $0 \leq \theta \leq \pi/2$ ; $0 \leq \varphi < 2\pi$ . This matrix shall be: + +$$TPM \#6 = \begin{bmatrix} e^{j\varphi} \cos \theta & 0 \\ \sin \theta & 0 \end{bmatrix}; \quad 0 \leq \theta \leq \frac{\pi}{2}; \quad 0 \leq \varphi < 2\pi$$ + +The quantization of the angles $\theta$ and $\varphi$ is described in clause 7.1.4.4.1.6. + +###### 7.1.4.4.1.8 The "precoding without SS 1 input" mapping, *TPM #7* + +The Tx port mapping matrix for use with precoding with spatial stream 2 transmission is defined by the angles $\theta$ and $\varphi$ , $0 \leq \theta \leq \pi/2$ ; $0 \leq \varphi < 2\pi$ . This matrix shall be: + +$$TPM \#7 = \begin{bmatrix} 0 & -e^{j\varphi} \sin \theta \\ 0 & \cos \theta \end{bmatrix}; \quad 0 \leq \theta \leq \frac{\pi}{2}; \quad 0 \leq \varphi < 2\pi$$ + +The quantization of the angles $\theta$ and $\phi$ is described in clause 7.1.4.4.1.6. + +##### 7.1.4.4.2 Tx port mapping allocation table (MAT) + +Tx port mapping is defined by a Tx port mapping allocation table (MAT) that associates sub-carrier indices with specific Tx port mapping matrices applied to those sub-carriers. The order of sub-carrier indices in a MAT shall be in ascending order, from the smallest index to the largest index, according to sub-carrier indexing defined in clause 7.1.4.1 (same as in the BATs). + +The MAT used by the node in a particular PHY frame is part of the BMAT (specified in clause 7.1.4.4.3) and shall be indicated to the receiving node(s) in the BMAT\_ID field of the MSG/BMSG/BACK/PROBE PHY-frame type specific fields of the PHY-frame header, as described in clause 7.1.2.3.2.2.8. + +The MAT shall only be used for mapping two spatial streams and only with Tx port mapping matrices TPM#0, TPM#3, TPM#4, TPM#5, TPM#6 and TPM#7. Tx port mapping matrices TPM#1 and TPM#2 are defined for specifying port mapping for transmissions using a single spatial stream. In this case, the same Tx port mapping matrix applies to all sub-carriers. + +###### 7.1.4.4.2.1 Predefined MATs + +The following predefined MATs are defined: + +- 1) Predefined MAT Type 0: Uniform Tx port mapping using the "Tx port 1" mapping matrix (TPM#3), defined in clause 7.1.4.4.1.4 on the sub-carriers set used by the corresponding BATs of the two spatial streams (i.e., on all sub-carriers except for either the PMSC set or the PMSC and RMSC sets). +- 2) Predefined MAT Type 1: Uniform Tx port mapping using the "Tx port 2" mapping matrix (TPM#4), defined in clause 7.1.4.4.1.5 on the sub-carriers set used by the corresponding BATs of the two spatial streams (i.e., on all sub-carriers except for either the PMSC set or the PMSC and RMSC sets). +- 3) Predefined MAT Type 2: Uniform Tx port mapping using the direct mapping matrix (TPM#0), defined in clause 7.1.4.4.1.1 on the sub-carriers set used by the corresponding BATs of the two spatial streams (i.e., on all sub-carriers except for either the PMSC set or the PMSC and RMSC sets). + +Every node shall support predefined MATs of Type 0, 1 and 2. + +###### 7.1.4.4.2.2 Runtime MATs + +A runtime MAT associates indices of SSCs with the Tx port mapping associated with each sub-carrier. In a MIMO transmission, the MAT is selected together with the two BATs. This combined allocation is called the BMAT (bit and Tx port mapping allocation table) and is described in clause 7.1.4.4.3. + +###### 7.1.4.4.2.3 MAT with sub-carrier precoding grouping + +Whenever MIMO mode 1 or 2 is used (see clause 8.11), the receiver may use sub-carrier precoding grouping of $PG = 1$ (no grouping), 2, 4, 8 and 16 sub-carriers with subsequent frequencies for communicating the quantized precoding parameters (angles) to the transmitter. If precoding grouping is used ( $PG > 1$ ), all sub-carriers of the same group (the number of sub-carriers in a group is $PG$ ) shall use the same precoding parameters (angles). The first group shall include $PG$ sub-carriers in ascending order of sub-carrier indices defined in clause 7.1.4.1. If a group includes sub-carriers that are masked (e.g., MSC) or extends beyond the applicable sub-carrier set, the node shall apply the precoding parameters (angles) assigned for this group only to the applicable sub-carrier set. The default value is $PG = 1$ . + +The precoding grouping ( $PG$ ) can be negotiated during channel estimation initiation using the MCE\_Initiation.req and MCE\_Initiation.cnf messages, as specified in clause 8.11.1.1.1. In addition + +to these messages, *PG* shall also be indicated in the MCE\_ParamUpdate.req message, when the BMAT is communicated (if this BMAT contains the precoding parameters), as described in clause 8.11.1. + +##### 7.1.4.4.3 Bit and Tx port mapping allocation tables (BMAT) + +The BMAT is the combination of the following elements: + +- The bit allocation tables (BATs) for the payload of the PHY frame (see clause 7.1.4.2.2): + - The BAT of spatial stream 1, BAT(1). + - The BAT of spatial stream 2, BAT(2). +- The Tx port mapping allocation table (MAT) for the payload of the PHY frame (specified in clause 7.1.4.4.2). + +The BMAT used by the node in a particular PHY frame shall be indicated to the receiving node(s) in the BMAT\_ID field of the MSG/BMSG/BACK/PROBE PHY-frame type specific fields of the PHY-frame header, as described in clause 7.1.2.3.2.2.8. + +###### 7.1.4.4.3.1 Predefined and runtime BMATs + +Table 7-3 describes the various combinations of the two BATs and MAT composing the BMAT. The BMAT is composed of predefined allocations (BMAT\_IDs values in the range 0 to 11) and of runtime allocations (BMAT\_IDs values in the range 16 to 27). + +Runtime BMATs can be defined by the receiving node (receiver-defined BMAT) for a specific unicast channel or selected by the transmitting node (transmitter-determined BMAT) for a specific multicast channel. Runtime BMATs shall be communicated from the node that generates the BMAT to the peer (e.g., a node sourcing multicast transmission to several other nodes will communicate the BMAT to all receiving nodes prior to sending data) (see clause 8.11 and clause 8.16). + +Runtime BMATs shall be created such that the coding of the two BATs composing this BMAT conveys the Tx port mapping information as well as bit-loading information for each sub-carrier. Values either in the range 0 to 12 or a special value of 15 shall be assigned per sub-carrier for each spatial stream as per the following rules (see also Table 8-27): + +- For cases in which, for a specific sub-carrier, either a single Tx port mapping (i.e., *TPM#3* or *TPM#4*) or a precoding with single spatial stream mapping (i.e., *TPM#6* or *TPM#7*) is to be assigned, the value of 15 is assigned to the spatial stream that is not mapped to a Tx port. This stream is allocated with zero bit loading and is not loaded by pseudo-randomly LFSR-generated bits (although the LFSR is advanced for this stream and sub-carrier). The other spatial stream shall be assigned a value in the range 0 to 12. The value 0 indicates that bits are taken from the LFSR (the LFSR used to load "unloaded sub-carriers", see clause 7.1.4.2.5) and loaded onto this spatial stream. +- For cases in which, for a specific sub-carrier, mappings of two spatial streams to two Tx ports (i.e., *TPM#0* or *TPM#5*) is to be assigned, the values in the range 0 to 12 are assigned to the two spatial streams. The value 0 indicates that bits are taken from the LFSR used to load "unloaded sub-carriers" (see clause 7.1.4.2.5) and loaded onto the specific spatial stream and sub-carrier. Other values in the range 1 to 12 indicate the number of bits loaded on the sub-carrier. + +###### 7.1.4.4.3.2 Transmitter-determined and receiver-determined BMATs + +Two types of mapping are defined: transmitter-determined and receiver-determined. With transmitter-determined mapping, the BMAT is defined by the transmitter and shall be either a predefined BMAT or it shall be communicated to all destination nodes prior to transmission using the channel estimation protocol for unicast transmission (see clause 8.11) and in addition using the multicast binding protocol for multicast transmission (see clause 8.16). With receiver-determined + +mapping, the BMAT is defined by the receiver of the destination node and communicated to the transmitter using the channel estimation protocol. + +For unicast transmission, the node shall use either one of the predefined BMATs or a runtime BMAT determined by the receiver. + +PHY multicast transmissions from an ITU-T G.9963 node may use either of the following two transmission schemes (as specified in clause 8.16): + +- ITU-T G.9960 transmission. +- MIMO transmission with the payload created as a single SS. + +For multicast transmission using either of these schemes, only BATs are defined (and not BMATs). Both predefined BATs (transmitter determined) and runtime BATs can be used. If a runtime BAT is used, it shall be defined by the node sourcing the multicast (transmitter-determined); this node shall generate the BAT and communicate it to all multicast destinations (see clause 8.16). + +Both transmitter-determined and receiver-determined BMATs may be defined, that are valid for only specific portions of the MAC cycle. The portion of the MAC cycle for which a specific BMAT is valid for is called a BMAT region. In the case of receiver-determined BMATs the applicable BMAT region(s) including the starting point and ending point of each of the BMAT regions with respect to the MAC cycle are conveyed to the transmitter as a part of the channel estimation protocol. + +![Figure 7-9: A diagram showing a sinusoidal AC line cycle (50/60 Hz) and a MAC cycle (33.3/40 msec). The AC line cycle is shown as a purple sine wave. The MAC cycle is indicated by a horizontal double-headed arrow at the bottom, spanning approximately half an AC cycle. Vertical dashed lines divide the MAC cycle into segments. Above the sine wave, the segments are labeled T1 (red) and T2 (green) in alternating order: T1, T2, T1, T2, T1, T2, T1, T2. T1 segments correspond to the peaks of the AC cycle, and T2 segments correspond to the zero crossings. The diagram is labeled G.9963(11)_F7-9 in the bottom right corner.](308c247b6837fbd1b1bcfb0cba273afc_img.jpg) + +Figure 7-9: A diagram showing a sinusoidal AC line cycle (50/60 Hz) and a MAC cycle (33.3/40 msec). The AC line cycle is shown as a purple sine wave. The MAC cycle is indicated by a horizontal double-headed arrow at the bottom, spanning approximately half an AC cycle. Vertical dashed lines divide the MAC cycle into segments. Above the sine wave, the segments are labeled T1 (red) and T2 (green) in alternating order: T1, T2, T1, T2, T1, T2, T1, T2. T1 segments correspond to the peaks of the AC cycle, and T2 segments correspond to the zero crossings. The diagram is labeled G.9963(11)\_F7-9 in the bottom right corner. + +**Figure 7-9 – An example of BMAT regions in a MAC cycle for a power line** + +Figure 7-9 illustrates multiple BMAT regions for a power line. In this example, the BMAT regions are periodic about half an AC line cycle and it has two BMATs. BMAT T1 is used around the peaks of the AC line cycle and BMAT T2 is used around the zero crossings of the AC line cycle. The receiver shall inform the transmitter about the starting point and the ending point of each of the BMAT regions with respect to the MAC cycle as a part of the channel estimation protocol. + +A node shall support both transmitter-determined and receiver-determined types of mapping. + +##### 7.1.4.4.4 Specific Tx port mappings of PHY-frame elements + +###### 7.1.4.4.4.1 Tx port mapping of the PHY-frame header + +When an ITU-T G.9963 node uses MIMO transmission, the Tx port mapping of all header symbols shall be done using the "duplication" mapping matrix (i.e., *TPM#1*), defined in clause 7.1.4.4.1.2, on all sub-carriers except the PMSC set. + +###### 7.1.4.4.4.2 Tx port mapping of ACE symbols + +When an ITU-T G.9963 node uses MIMO transmission, the Tx port mapping of ACE symbols shall be done in the following way: + +- For the case where the transmission includes payload intended for an ITU-T G.9963 node and this payload is created as two spatial streams (i.e., MIMO\_IND = 1, case "4a" in Table 7-1): + - The odd numbered ACE symbols shall use the "duplicate and negate" mapping matrix (i.e., *TPM#2*), defined in clause 7.1.4.4.1.3, on the entire SSC set. + - The even numbered ACE symbols shall use the "duplication" mapping matrix (i.e., *TPM#1*), defined in clause 7.1.4.4.1.2, on the entire SSC set. + +For this case, one ACE symbol following the header shall be mandatory, additional ACE symbols are optional. + +- For all other cases where the transmission includes payload (i.e., MIMO\_IND = 0, cases "4b", "5" and "6" in Table 7-1): + - The ACE symbols shall use the "duplication" mapping matrix (i.e., *TPM#1*), defined in clause 7.1.4.4.1.2, on the entire SSC set. + +For these cases, all ACE symbols are optional. + +##### 7.1.4.4.3 Tx port mapping of probe symbols + +The Tx port mapping of the 1 SS channel estimation probe symbols shall be done using the "duplication" mapping matrix (i.e., *TPM#1*), defined in clause 7.1.4.4.1.2, on the entire SSC set. + +The Tx port mapping of the 2 SS channel estimation probe symbols shall be done using the MAT corresponding to the BMAT\_ID indicated in the field PRB\_BMAT\_ID of the PROBE frame. + +##### 7.1.4.4.4 Mappings of payload symbols for RCM + +When an ITU-T G.9963 node uses MIMO transmission in RCM, the Tx port mapping for the payload shall be done using the "duplication" mapping matrix (i.e., *TPM#1*), defined in clause 7.1.4.4.1.2, on all of the payload sub-carriers. + +#### 7.1.4.5 OFDM modulator + +A MIMO transceiver comprises two OFDM modulators, one for each one of the two Tx ports. An OFDM modulator of an individual Tx port consists of the following major parts: IDFT, cyclic shift, cyclic extension, windowing, overlap and add and frequency up-shift. The incoming signal to the modulator of the $q$ -th Tx port at the $l$ -th OFDM symbol in the present frame for a single sub-carrier, with index $i$ , is the complex value $Z_{i,l}^{(q)}$ generated by the Tx port mapper as described in clause 7.1.4.4 (for symbols of the header and the payload) or by the preamble generator as described in clause 7.1.4.6.3 (for symbols of the preamble). + +Time-domain samples generated by the IDFT ( $y_{n,l}^{(q)}$ ) are input to the cyclic shift. The output of the cyclic shift ( $x_{n,l}^{(q)}$ ) is input to the cyclic prefix. The output of the cyclic prefix ( $v_{n,l}^{(q)}$ ) is input to the windowing, overlap and add. The output of the windowing, overlap and add ( $u_n^{(q)}$ ) is then frequency up-shifted by $F_{US}$ to generate $s_n^{(q)}$ . The functional diagram of the OFDM modulator is presented in Figure 7-10. + +![Functional model of the OFDM modulator block diagram. The input Z_{i,l}^{(q)} enters an IDFT block, producing y_{n,l}^{(q)}. This is followed by a Cyclic shift block producing x_{n,l}^{(q)}, then a Cyclic prefix N_{CP} block producing v_{n,l}^{(q)}. Next is a Windowing, overlap and add block producing u_n^{(q)}, and finally a Frequency up-shift block producing the output s_n^{(q)}. The Frequency up-shift block also receives F_{US} as an input. The entire sequence of blocks is labeled 'OFDM modulator'. A reference code G.9963(11)_F7-10 is shown at the bottom right.](dbd074feb5cce1300f42f91da8f673d1_img.jpg) + +Functional model of the OFDM modulator block diagram. The input Z\_{i,l}^{(q)} enters an IDFT block, producing y\_{n,l}^{(q)}. This is followed by a Cyclic shift block producing x\_{n,l}^{(q)}, then a Cyclic prefix N\_{CP} block producing v\_{n,l}^{(q)}. Next is a Windowing, overlap and add block producing u\_n^{(q)}, and finally a Frequency up-shift block producing the output s\_n^{(q)}. The Frequency up-shift block also receives F\_{US} as an input. The entire sequence of blocks is labeled 'OFDM modulator'. A reference code G.9963(11)\_F7-10 is shown at the bottom right. + +**Figure 7-10 – Functional model of the OFDM modulator** + +The functional diagram presented above and other figures presented in this section do not imply any specific implementation. All aspects of signal processing used in the modulator shall comply with equations and textual descriptions. + +##### 7.1.4.5.1 IDFT + +The IDFT converts the stream of the $N$ complex numbers $Z_{i,l}^{(q)}$ at its input into the stream of $N$ complex time-domain samples $y_{n,l}^{(q)}$ . The input numbers represent the $N$ mapped blocks of data, where the $i$ -th block of data represents the complex value $Z_{i,l}^{(q)}$ of the $i$ -th modulated sub-carrier of the OFDM signal, where $i = 0, 1, \dots, N-1$ is the sub-carrier index, $l$ is the sequential number of the OFDM symbol within the current frame, excluding the preamble and $q = 1$ or $2$ is the Tx port index. The conversion shall be performed in accordance with the equation: + +$$y_{n,l}^{(q)} = \sum_{i=0}^{N-1} \exp\left(j \cdot 2\pi \cdot i \frac{n}{N}\right) \cdot Z_{i,l}^{(q)} \quad \text{for } n = 0 \text{ to } N-1, \quad l = 0 \text{ to } M_F - 1, \quad q = 1,2$$ + +where $M_F$ denotes the total number of OFDM symbols in the current frame excluding the preamble symbols and the value of $N$ represents the maximum number of possibly modulated sub-carriers in the OFDM spectrum and shall be a power of 2: $N = 2^k$ , where $k$ shall be an integer. The value of $Z_{i,l}^{(q)}$ for all masked sub-carriers shall be set to 0. If some non-masked sub-carriers with indices $i < N$ are not loaded with data bits, the corresponding values of $Z_{i,l}^{(q)}$ shall be generated as described in clause 7.1.4.2.5. + +##### 7.1.4.5.2 Cyclic shift + +The cyclic shift cyclically shifts the samples of an OFDM symbol at the output of the IDFT, $y_{n,l}^{(q)}$ , to generate a shifted-version of this sequence, $x_{n,l}^{(q)}$ . This shift depends on both the Tx port index and symbol type (preamble, PHY frame header, ACE and payload). This operation is defined by the following equation: + +$$x_{n,l}^{(q)} = y_{(n - CS_l^{(q)}) \bmod N, l}^{(q)} = \sum_{i=0}^{N-1} Z_{i,l}^{(q)} \times \exp\left(j \cdot 2\pi \cdot i \frac{n - CS_l^{(q)}}{N}\right), \text{ for } n = 0, 1, \dots, N-1 \text{ and } q = 1,2.$$ + +where $CS_l^{(q)}$ is the cyclic shift for power lines used for the $l$ -th OFDM symbol of the $q$ -th Tx port. The values of the cyclic shift for the two Tx ports and the different OFDM symbols are listed in Table 7-17. + +**Table 7-17 – Cyclic shift values for power lines (OFB Profile 1)** + +| Symbol type | Number of sub-carriers–( N ) | | | Cyclic shift for Tx Port 1 ( q = 1) [samples] | Cyclic shift for Tx Port 2 ( q = 2) [samples] | +|----------------------------------|-------------------------------------|--------|---------|------------------------------------------------------|------------------------------------------------------| +| | 25 MHz | 50 MHz | 100 MHz | | | +| Preamble | 128 | 256 | 512 | 0 | N /8 | +| INUSE, PR, NACK and IDPS signals | 128 | 256 | 512 | 0 | N /8 | +| Header | 1024 | 2048 | 4096 | 0 | N /64 | +| ACE symbol | 1024 | 2048 | 4096 | 0 | N /64 | +| Payload | 1024 | 2048 | 4096 | 0 | N /64 | + +In the phoneline cable case, a cyclic shift shall not be applied to either Tx port. + +NOTE – The cyclic shift is not needed in phoneline cables since the crosstalk between the two pairs is low compared to the direct signal. + +The use of MIMO for OFB Profile 2 is for further study. + +##### 7.1.4.5.3 Cyclic extension + +The cyclic extension provides a guard interval between adjacent OFDM symbols. This guard interval is intended to protect against inter-symbol interference (ISI). Symbols at Tx port #1 and Tx port #2 with the same number (as defined in clause 7.1.4.5.1) use the same GI value. + +In OFDM, the cyclic prefix of the *l*-th OFDM symbol in the frame shall be implemented by pre-pending the last *NCP(l)* samples of the IDFT output to its output *N* samples to create a pre-overlapped OFDM symbol, as presented in Figure 7-11. The order of samples in the symbol shall be as follows: + +- The first sample of the symbol is the cyclic shift output sample *N* – *NCP(l)*; +- The last sample of the cyclic prefix is the cyclic shift output sample *N* – 1; the next sample is the cyclic shift output sample 0. + +The *l*-th pre-overlapped OFDM symbol consists of *N* IDFT samples and *NCP(l)* cyclic extension, samples, in total: + +$$N_W(l) = N + N_{CP}(l) \text{ [samples]}.$$ + +After cyclic extension as described above, time-domain samples at the reference point $v_{n,l}^{(q)}$ in Figure 7-23 shall comply with the following equations: + +$$v_{n,l}^{(q)} = x_{n-N_{CP}(l),l}^{(q)} = \sum_{i=0}^{N-1} Z_{i,l}^{(q)} \times \exp\left(j \cdot 2\pi \cdot i \cdot \frac{n - CS_l^{(q)} - N_{CP}(l)}{N}\right). \quad \text{for } n = 0 \text{ to } N_W(l) - 1 = N + N_{CP}(l) - 1$$ + +The number of IDFT samples, *N* and the number of windowed samples, $\beta$ , shall be the same for all symbols of the same frame. The value of *NCP(l)* (and the duration of the pre-overlapped OFDM symbol *Nw(l)*, accordingly) may change during the course of the frame, as follows: + +- All symbols of the header shall have the value of *NGI-HD*+ $\beta$ defined in clause 7.1.4.7; +- The first two symbols following the header shall have the default value *NGI-DF*+ $\beta$ , defined in clause 7.1.4.7; +- All the rest of the payload symbols shall have the same value *NGI*+ $\beta$ , where *NGI* is selected from the valid values defined in clause 7.1.4.7 and indicated in the header, as described in clause 7.1.2.1. + +##### 7.1.4.5.4 Symbol timing + +The PHY frame consists of a preamble followed by an integer number, $M_F$ , of OFDM symbols. The first symbol following the preamble (the first symbol of the PHY-header) shall have symbol count 0 and the last symbol of the frame shall have symbol count $M_F - 1$ . The time position of each symbol in the frame is defined by sample count. The first sample of the symbol with symbol count 0 shall have sample count $M(0) = N_{pr} - \beta$ , where $N_{pr}$ is the number of samples in the preamble. The count of the first sample of the $l$ -th symbol ( $l = 1, 2, \dots, M_F - 1$ ) in the frame shall be: + +$$M(l) = N_{pr} - \beta + \sum_{k=0}^{l-1} N_S(k),$$ + +where $N_S(k) = N + N_{CP}(k) - \beta$ and $N_S(k)$ may be different for symbols of the header and payload, as described in clause 7.1.4.7. + +##### 7.1.4.5.5 Windowing, overlap and add + +![Figure 7-11: Structure of an OFDM symbol with cyclic extension and overlapped windowing. The diagram shows a time-domain signal with a bell-shaped window function overlaid on a rectangular pulse. The total duration of the OFDM symbol is labeled as N_s = N + N_cp(l) - beta. The duration of the guard interval is labeled as N_GI(l). The duration of the cyclic prefix is labeled as N_cp(l). The duration of the useful data is labeled as N. The duration of the pre-overlapped OFDM symbol is labeled as N_W(l) samples. The windowing function is applied to the first beta samples and the last beta samples of the symbol. The overlap between adjacent symbols is indicated by the beta samples at the beginning and end of the symbol.](df1966d80c74bc127f159a48f38b13ee_img.jpg) + +Figure 7-11: Structure of an OFDM symbol with cyclic extension and overlapped windowing. The diagram shows a time-domain signal with a bell-shaped window function overlaid on a rectangular pulse. The total duration of the OFDM symbol is labeled as N\_s = N + N\_cp(l) - beta. The duration of the guard interval is labeled as N\_GI(l). The duration of the cyclic prefix is labeled as N\_cp(l). The duration of the useful data is labeled as N. The duration of the pre-overlapped OFDM symbol is labeled as N\_W(l) samples. The windowing function is applied to the first beta samples and the last beta samples of the symbol. The overlap between adjacent symbols is indicated by the beta samples at the beginning and end of the symbol. + +**Figure 7-11 – Structure of an OFDM symbol with cyclic extension and overlapped windowing** + +The first $\beta$ samples of the cyclic prefix and last $\beta$ samples of the cyclic shift output shall be used for shaping the envelope of the transmitted signal (windowing). The window function facilitates PSD shaping: it allows sharp PSD roll-offs used to create deep spectral notches and reduction of the out-of-band PSD. The number of windowed samples, $\beta$ , shall be the same for all of the payload symbols of the same frame, as well as the PHY-header and preamble. + +To reduce the modulation overhead, the windowed samples of adjacent symbols shall overlap, as shown in Figure 7-11. The value of $N_{CP}(l) - \beta = N_{GI}(l)$ forms the guard interval. The duration of the $l$ -th OFDM symbol after overlap is thus $N_S(l) = N + N_{CP}(l) - \beta$ . + +After applying the windowing and the overlap and add functions, the time-domain samples at the reference point $u_n^{(q)}$ in Figure 7-10 shall comply with the following equations: + +$$u_n^{(q)} = u_n^{(pr,q)} + \sum_{l=0}^{M_F-1} w(n - M(l), l) \times u_{n-M(l),l}^{(q)} \quad \text{for } n = 0 \text{ to } M(M_F - 1) + N_W(M_F - 1) - 1,$$ + +where $u_n^{(pr,q)}$ is the $n$ -th sample of the preamble of the $q$ -th Tx port, as defined in clause 7.1.4.6 (the signal $u_n^{(pr,q)}$ already includes windowing as necessary), $w(n,l)$ is the windowing function defined on $N_W(l)$ samples of the pre-overlapped OFDM symbol in the following way: + +$$w(n,l) = \begin{cases} w_\beta(n) & 0 \leq n < \beta \\ 1 & \beta \leq n < N_W(l) - \beta \\ w_\beta(N_W(l) - 1 - n) & N_W(l) - \beta \leq n < N_W(l) \\ 0 & \text{otherwise} \end{cases}$$ + +where $w_\beta(n)$ is the function describing the roll-off section of the window. The roll-off function $w_\beta(n)$ shall be vendor discretionary. + +However, $w_\beta(n)$ shall comply with the following rules: + +- $w_\beta(n) + w_\beta(\beta-n-1) = 1$ for $0 \leq n < \beta$ . +- $0 \leq w_\beta(n) \leq 1$ . + +The symbol rate $f_{OFDM}$ (number of symbols per second) and symbol period $T_{OFDM}$ for the given value of $N_{CP}$ and $\beta$ shall be computed, respectively, as: + +$$f_{OFDM} = \frac{N \times F_{SC}}{N + N_{CP} - \beta},$$ + +and $T_{OFDM} = 1/f_{OFDM}$ . + +##### 7.1.4.5.6 Frequency up-shift + +The frequency up-shift offsets the spectrum of the transmit signal shifting it by $F_{US}$ . The value of $F_{US}$ shall be a multiple of the sub-carrier frequency $F_{SC}$ : + +$$F_{US} = N/2 * F_{SC}$$ + +The real and imaginary components of the signal after frequency up-shift (reference point $s_n^{(q)}$ in Figure 7-10) shall be as follows: + +$$\begin{aligned} s_n^{(q)} &= u_{n/p}^{(q)} \times \exp\left(j \frac{\pi n}{p}\right) = \operatorname{Re}(s_n^{(q)}) + j \operatorname{Im}(s_n^{(q)}) & \text{for } n = 0 \text{ to } [M(M_F - 1) + N_W(M_F - 1)] \times p - 1; \\ \operatorname{Re}(s_n^{(q)}) &= \operatorname{Re}(u_{n/p}^{(q)}) \cos\left(\frac{\pi n}{p}\right) - \operatorname{Im}(u_{n/p}^{(q)}) \sin\left(\frac{\pi n}{p}\right) \\ \operatorname{Im}(s_n^{(q)}) &= \operatorname{Re}(u_{n/p}^{(q)}) \sin\left(\frac{\pi n}{p}\right) + \operatorname{Im}(u_{n/p}^{(q)}) \cos\left(\frac{\pi n}{p}\right) \end{aligned}$$ + +where $u_{n/p}^{(q)}$ is $u_n^{(q)}$ after interpolation with factor $p$ . The interpolation factor $p$ is vendor discretionary and shall be equal to or higher than 2. + +NOTE 1 – The minimum value of $p$ sufficient to avoid distortions depends on the ratio between the up-shift frequency $F_{US}$ and the bandwidth of the transmit signal $BW = N * F_{SC}$ . It is assumed that an appropriate low-pass filter is included to reduce imaging. + +NOTE 2 – The phase of the up-shift should be initialized to zero at the first sample of the preamble and be advanced by $\frac{\pi}{p}$ per each sample (after interpolation). + +##### 7.1.4.5.7 Output signal + +The output signal of the modulator shall be the real component of $s_n^{(q)}$ : + +$$s_{\text{OUT-HF}}^{(q)} = \operatorname{Re}(s_n^{(q)}).$$ + +#### 7.1.4.6 Preamble, INUSE, PR, NACK and IDPS signals + +##### 7.1.4.6.1 General preamble structure + +See clause 7.1.4.5.1 of [ITU-T G.9960]. + +##### 7.1.4.6.2 INUSE, PR, NACK and IDPS signals general structure + +See clause 7.1.4.5.2 of [ITU-T G.9960]. + +##### **7.1.4.6.3 Preamble, INUSE, PR, NACK and IDPS signal generation** + +See clause 7.1.4.5.3 of [ITU-T G.9960] and its subclauses. When an ITU-T G.9963 node uses MIMO transmission, the preamble, INUSE, PR, NACK and IDPS signals shall each be created as a single spatial stream. In this case, the Tx port mapping shall be done using the "duplication" mapping matrix (i.e., *TPM#1*), defined in clause 7.1.4.4.1.2, on all of the signal's sub-carriers. + +#### **7.1.4.7 PMD control parameters** + +See clause 7.1.4.6 of [ITU-T G.9960]. + +#### **7.1.4.8 Symbol boost** + +See clause 7.1.4.7 of [ITU-T G.9960]. + +### **7.1.5 Transmit PSD mask** + +See clause 7.1.5 of [ITU-T G.9960]. + +### **7.1.6 Electrical specifications** + +See clause 7.1.6 of [ITU-T G.9960]. + +## **7.2 Medium dependent specification** + +### **7.2.1 Physical layer specification** + +See clause 7.2.1 of [ITU-T G.9960] and clause 6.1 of [ITU-T G.9964] for phoneline cables. + +See clause 7.2.2 of [ITU-T G.9960] and clause 6.2 of [ITU-T G.9964] for power lines. + +### **7.2.2 Transmitter EVM requirements** + +See clause 7.2.4 of [ITU-T G.9960]. + +### **7.2.3 Termination impedance** + +See clause 6.4 of [ITU-T G.9964]. + +### **7.2.4 Total transmit power** + +See clause 6.5 of [ITU-T G.9964]. + +### **7.2.5 Receiver input impedance** + +See clause 6.6 of [ITU-T G.9964]. + +### **7.2.6 Longitudinal conversion loss** + +See clause 7.2.8 of [ITU-T G.9960]. + +# **8 Data link layer specification of the MIMO transceiver** + +## **8.1 Functional model and frame formats** + +See clause 8.1 of [ITU-T G.9961]. + +## **8.2 MAP controlled medium access** + +See clause 8.2 of [ITU-T G.9961]. + +## **8.3 Transmission opportunities (TXOPs) and time slots (TSs)** + +See clause 8.3 of [ITU-T G.9961]. + +## 8.4 Control parameters for APC, LLC and MAC + +See clause 8.4 of [ITU-T G.9961] but with the following exceptions for power-line and phoneline cable baseband: + +- For transmissions using 2 spatial streams (i.e., MIMO\_IND = 1), the value of MIN\_SYM\_VAR\_AIFG\_DEFAULT shall be 3. +- For transmissions using 1 spatial stream, the value of MIN\_SYM\_VAR\_AIFG\_DEFAULT shall be 2. + +## 8.5 Functions of the endpoint node + +See clause 8.5 of [ITU-T G.9961]. + +## 8.6 Domain master node functional capabilities + +See clause 8.6 of [ITU-T G.9961]. + +### 8.6.1 Network admission + +See clause 8.6.1 of [ITU-T G.9961]. + +#### 8.6.1.1 Network admission protocol + +##### 8.6.1.1.1 Registration into the domain + +See clause 8.6.1.1.1 of [ITU-T G.9961]. + +##### 8.6.1.1.2 Periodic re-registrations + +See clause 8.6.1.1.2 of [ITU-T G.9961]. + +##### 8.6.1.1.3 Resignation from the domain + +See clause 8.6.1.1.3 of [ITU-T G.9961]. + +##### 8.6.1.1.4 Registration and resignation messages + +See clause 8.6.1.1.4 of [ITU-T G.9961] and its subclauses. + +Additionally, see clause 8.6.1.1.4.1 of [ITU-T G.9961] after replacing the references to Tables 8-16.8 by the following Table 8-0. + +**Table 8-0 – Run-length compression support** + +| Field | Octet | Bits | Description | +|------------------|-------|-------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| BAT compression | 0 | [0] | See Table 8-16.8 in [ITU-T G.9961] | +| BMAT compression | 0 | [1] | If set to one, it indicates the capability of the node to compress and decompress BMAT fields (BAT and Precoding parameters) of MCE_ParamUpdate.req messages making use of the run-length compression mechanism described in clause 8.24 of ITU-T G.9963, zero otherwise. If this bit is set to one, the BAT compression field shall also be set to one. | +| Reserved | 0 | [7:2] | See Table 8-16.8 in [ITU-T G.9961] | + +#### 8.6.1.2 Admission via proxy + +See clause 8.6.1.2 of [ITU-T G.9961]. + +#### **8.6.1.3 Domain information maintenance after node admission** + +In addition to the actions specified in clause 8.6.1.3 of [ITU-T G.9961], when a new node is admitted into the domain, the DM shall update the related MIMO domain wide information in order to take into account backward compatibility issues. + +If any of the information included in the additional domain information auxiliary information sub-field of the MAP needs to be updated based on the node-information of the registering node (see Table 8-16.1 of [ITU-T G.9961]), the DM shall send a MAP-A with an updated additional MIMO domain information auxiliary information sub-field. The domain master shall use the validity counter-based update (AUX\_VALID = 3 and ModificationFlag = 1). + +Whenever a registering node indicates in its node-information during registration that it does not support a DM-defined initial seed (see clause 7.1.4.2.6 of [ITU-T G.9960]) the DM shall update the UnloadedSubcarrierInitialSeedStream1 and UnloadedSubcarrierInitialSeedStream2 fields of the additional MIMO domain information auxiliary information sub-field to the default value. + +### **8.6.2 Bandwidth management** + +See clause 8.6.2 of [ITU-T G.9961]. + +### **8.6.3 Synchronization to an external source** + +See clause 8.6.3 of [ITU-T G.9961]. + +### **8.6.4 Routing and topology management** + +See clause 8.6.4 of [ITU-T G.9961]. + +### **8.6.5 Backup domain master** + +See clause 8.6.5 of [ITU-T G.9961]. + +### **8.6.6 Domain master selection** + +See clause 8.6.6 of [ITU-T G.9961]. + +## **8.7 Addressing scheme** + +See clause 8.7 of [ITU-T G.9961]. + +## **8.8 Medium access plan (MAP) frame** + +See clause 8.8 of [ITU-T G.9961]. + +### **8.8.1 MAP generation and distribution** + +See clause 8.8.1 of [ITU-T G.9961]. + +### **8.8.2 MAP frame transmission** + +See clause 8.8.2 of [ITU-T G.9961]. + +### **8.8.3 MAP header** + +See clause 8.8.3 of [ITU-T G.9961]. + +### **8.8.4 TXOP descriptor** + +See clause 8.8.4 of [ITU-T G.9961] and all its subclauses. + +### **8.8.5 Auxiliary information field** + +See clause 8.8.5 of [ITU-T G.9961]. + +Additionally, Table 8-1 provides additional types of auxiliary information sub-fields, valid for MIMO nodes. + +**Table 8-1 – Types of auxiliary information sub-fields** + +| Type | Value | Description | +|------------------------------------|------------------|-----------------------------------------------------------------------------| +| Additional MIMO Domain Information | 11 16 | A sub-field indicating additional MIMO domain information. See clause 8.8.7 | + +### 8.8.6 MAP schedule persistence publication + +See clause 8.8.6 of [ITU-T G.9961]. + +### 8.8.7 Additional MIMO domain information sub-field + +The format of the Domain Info sub-field shall be as presented in Table 8-2. The length of the sub-field data is 8 octets. + +**Table 8-2 – Format of additional MIMO domain information sub-field** + +| Field | Octet | Bits | Description | +|--------------------------------------|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Type | 0 | [6:0] | Set to 11 16 . | +| ModificationFlag | | [7] | This flag shall be set to one. | +| Length | 1 | [7:0] | Set to the length of the MIMO domain information sub-field (excluding the Type, ModificationFlag and Length) in octets (See Table 8-72 of [ITU-T G.9961]) | +| UnloadedSubcarrierInitialSeedStream1 | 2 to 5 | [22:0] | Value of the DM-generated seed to be used during modulation of unloaded supported sub-carriers for spatial stream 1(see clause 7.1.4.2.5) | +| Reserved | | [31:23] | Reserved by ITU-T (Note). | +| UnloadedSubcarrierInitialSeedStream2 | 6 to 9 | [22:0] | Value of the DM-generated seed to be used during modulation of unloaded supported sub-carriers for spatial stream 2(see clause 7.1.4.2.5) | +| Reserved | | [31:23] | Reserved by ITU-T (Note). | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +## 8.9 Retransmission and acknowledgement protocol + +See clause 8.9 of [ITU-T G.9961]. + +## 8.10 Management and control message format + +### 8.10.1 Management message format + +See clause 8.10.1 of [ITU-T G.9961]. + +#### 8.10.1.1 Management message OPCODEs + +Management message OPCODEs are formatted as 12-bit unsigned integers. Valid values of OPCODEs are presented in Table 8-3 as well as Table 8-88 of [ITU-T G.9961]. OPCODEs are categorized (typically by their associated protocol or procedure) according to the value of their 8 MSBs. + +**Table 8-3 – OPCODEs of management messages** + +| Category | Message name | OPCODE (hex) | Description | MMPL reference | +|-----------------------------------|----------------------------|--------------|-----------------------------------------------------------|------------------| +| MIMO Channel Estimation (80X-89X) | MCE_ProbeSlotAssign.req | 800 | MIMO channel estimation bandwidth assignment request | Clause 8.11.7.1 | +| | MCE_ProbeSlotRelease.req | 801 | MIMO channel estimation bandwidth release request | Clause 8.11.7.2 | +| | MCE_ParamUpdate.req | 802 | MIMO channel estimation parameters update request | Clause 8.11.7.3 | +| | MCE_ParamUpdateRequest.ind | 803 | Request for MIMO channel estimation parameter update | Clause 8.11.7.4 | +| | MCE_PartialBmatUpdate.req | 804 | Partial BMAT update request | Clause 8.11.7.5 | +| | MCE_ACESymbols.ind | 805 | Request for an ACE symbol attachment | Clause 8.11.7.6 | +| | MCE_ProbeSlotAssign.cnf | 806 | MIMO channel estimation bandwidth assignment confirmation | Clause 8.11.7.7 | +| | MCE_ProbeSlotRelease.cnf | 807 | MIMO channel estimation bandwidth release confirmation | Clause 8.11.7.8 | +| | MCE_ParamUpdate.cnf | 808 | MIMO channel estimation parameters update confirmation | Clause 8.11.7.9 | +| | MCE_PartialBmatUpdate.cnf | 809 | Partial BMAT update confirmation | Clause 8.11.7.10 | +| | MCE_Request.ind | 80A | MIMO channel estimation trigger | Clause 8.11.7.11 | +| | MCE_Initiation.req | 80B | MIMO channel estimation initiation request | Clause 8.11.7.12 | +| | MCE_Initiation.cnf | 80C | MIMO channel estimation initiation confirmation | Clause 8.11.7.13 | +| | MCE_ProbeRequest.ind | 80D | Request for PROBE frame transmission | Clause 8.11.7.14 | + +**Table 8-3 – OPCODEs of management messages** + +| Category | Message name | OPCODE (hex) | Description | MMPL reference | +|----------|------------------------|--------------|---------------------------------------------------|------------------| +| | MCE_Cancellation.req | 80E | MIMO channel estimation cancellation request | Clause 8.11.7.15 | +| | MCE_BmatIdMaintain.ind | 80F | BMAT ID maintenance | Clause 8.11.7.16 | +| | MCE_Cancellation.cnf | 810 | MIMO channel estimation cancellation confirmation | Clause 8.11.7.17 | +| Reserved | Reserved | 820-9FF | Reserved by ITU-T | | + +#### **8.10.1.2 Management of message sequence numbers and segmentation** + +See clause 8.10.1.2 of [ITU-T G.9961]. + +### **8.10.2 Control message format** + +See clause 8.10.2 of [ITU-T G.9961]. + +## **8.11 Channel estimation protocol** + +ITU-T G.9963 nodes shall use the channel estimation protocol specified in clause 8.11 of [ITU-T G.9961] for links with ITU-T G.9960/G.9961 nodes and links with ITU-T G.9963 nodes using a single SS. + +ITU-T G.9963 nodes shall use the channel estimation protocol specified in clause 8.11.1 for links with ITU-T G.9963 nodes using two SSs. + +### **8.11.1 Channel estimation with ITU-T G.9963 transceivers using two spatial streams** + +The channel estimation protocol describes the procedure of measuring the characteristics of the channel between the transmitter (source) and the receiver (destination) nodes. The procedure involves initiation of channel estimation, transmissions of PROBE frames and selection of parameters. + +Channel estimation can be done in two phases: + +- Channel discovery – initial channel estimation. +- Channel adaptation – subsequent channel estimation to adapt to a changing channel. + +The protocols used for channel discovery and channel adaptation can be started either by the transmitter or by the receiver. The core part of the channel estimation protocol is identical in these two cases and is always initiated by the receiver (receiver-initiated channel estimation). The transmitter can request the receiver to initiate channel estimation (transmitter-requested channel estimation). + +During the initiation process, the transmitter and receiver jointly determine input parameters for channel estimation such as channel estimation window (a fraction of a MAC cycle over which channel estimation should be executed), the value of $G$ (see clause 7.1.4.2.3 of [ITU-T G.9960]), the value of $PG$ (see clause 7.1.4.4.2.3) and parameters for the PROBE frame. The receiver selects the BMAT\_ID associated with the triplet of the two BATs (each associated with a different spatial stream) and MAT, termed BMAT, to be updated. This BMAT\_ID is used as an identifier for a particular channel estimation process throughout the rest of the process. The receiver shall consider its own frequency information (namely the StartSubCarrier & StopSubCarrier) and that of the transmitter when + +calculating the BMAT. More specifically, the range of sub-carriers of the BMAT sent in the MCE\_ParamUpdate.req message shall be within the intersection of the sub-carrier ranges determined by the StartSubCarrier & StopSubCarrier of both the receiver and transmitter. + +Once the channel estimation process is initiated, the receiver may request the transmitter to send one or more PROBE frames. The receiver can change parameters of a PROBE frame at each request. If the receiver requests a PROBE frame without specifying its parameters (e.g., request for PROBE frame transmission via ACK\_CE\_CTRL as described in clause 8.11.1.4), the transmitter transmits the PROBE frame using parameters previously selected by the receiver. The receiver is not required to request PROBE frames if it chooses other means such as MSG frames or PROBE frames transmitted to other nodes to estimate the channel. + +The receiver terminates the channel estimation process by sending the outcome of channel estimation to the transmitter. This may include, but is not limited to, the following parameters: + +- Bit allocation tables (BATs). A BAT for each one of the two possible spatial streams. +- MIMO mode indicator, indicating the MIMO mode used (see Table 8-6). +- Precoding feedback quantization indicator. +- Precoding parameters. +- FEC coding rate and block size. +- Guard interval for payload. +- PSD ceiling. + +The receiver may cancel the channel estimation process without generating new channel estimation parameters. + +The protocol provides several options to expedite the channel estimation process for faster channel adaptation. For example, the channel estimation initiation process (clause 8.11.1.1.1) can be omitted in case of channel adaptation where no new input parameter negotiation is necessary. The receiver can create a new BMAT by sending an unsolicited MCE\_ParamUpdate.req (clause 8.11.1.3.1) or update the existing BMAT by sending an MCE\_PartialBmatUpdate.req (clause 8.11.1.3.2). The receiver can request PROBE frame transmission without going through the channel estimation initiation process (clause 8.11.1.4). + +#### **8.11.1.1 Receiver-initiated channel estimation** + +The following procedure describes the receiver-initiated channel estimation process: + +- 1) The receiver initiates the channel estimation process by sending the transmitter an MCE\_Initiation.req message. The receiver may request a PROBE frame transmission in this message (channel estimation initiation, see clause 8.11.1.1.1). +- 2) Upon reception of the channel estimation initiation request, if the transmitter does not have transmit opportunities for a given channel estimation window, it shall request the domain master to allocate bandwidth for PROBE frame transmission by sending an MCE\_ProbeSlotAssign.req message. The domain master shall confirm that it received the bandwidth request by replying with the MCE\_ProbeSlotAssign.cnf message (bandwidth request, see clause 8.11.1.1.2). +- 3) Depending on the availability of bandwidth, the transmitter may grant or reject the channel estimation initiation request by sending the receiver an MCE\_Initiation.cnf message (channel estimation initiation confirmation, see clause 8.11.1.1.3). + +- 4) Upon reception of the MCE\_Initiation.cnf message indicating channel estimation initiation confirmation, the receiver may request the transmitter to send additional PROBE frames by sending an MCE\_ProbeRequest.ind message or through the ACK\_CE\_CTRL field in the PFH of an ACK frame (request for PROBE frame transmission, see clause 8.11.1.1.4). +- 5) Upon reception of the request for PROBE frame transmission, the transmitter shall transmit the PROBE frame as the receiver requested (PROBE frame transmission, see clause 8.11.1.1.5). +- 6) Steps 4 and 5 can repeat until the receiver sends the transmitter the final outcome of channel estimation using the MCE\_ParamUpdate.req message. The transmitter shall confirm reception of the new parameters by sending an MCE\_ParamUpdate.cnf message (channel estimation completion, see clause 8.11.1.1.6). Steps 4 and 5 may be skipped altogether if the receiver does not need additional PROBE frames. +- 7) The receiver may cancel the channel estimation process any time after it receives the channel estimation initiation confirmation by sending an MCE\_Cancellation.req message (channel estimation cancellation, see clause 8.11.1.1.7). +- 8) Upon reception of an MCE\_ParamUpdate.req message, if the transmitter has been allocated extra bandwidth for the PROBE frame transmission, it shall send an MCE\_ProbeSlotRelease.req message to the domain master to release the bandwidth used for PROBE frame transmission. The domain master shall confirm the bandwidth release request by replying with an MCE\_ProbeSlotRelease.cnf message (bandwidth release, see clause 8.11.1.1.8). + +The transmitter may send frames carrying payload with the existing settings (e.g., any valid runtime BMAT or predefined BMAT) at any time during this process. + +The receiver-initiated channel estimation process is illustrated in Figure 8-1. + +![Sequence diagram for Receiver-initiated channel estimation. The diagram shows three participants: Transmitter node, Receiver node, and Domain master. The process starts with User data transmission (BMAT_ID=X) from Transmitter to Receiver, followed by an Acknowledgment for ARQ. The Receiver then sends MCE_Initiation.req to the Transmitter, which is annotated as 'Channel estimation initiation'. The Transmitter responds with MCE_ProbeSlotAssign.req, annotated as 'Bandwidth request for PROBE frame transmission', which is sent to the Domain master. The Domain master returns MCE_ProbeSlotAssign.cnf to the Transmitter, which then sends MCE_Initiation.cnf to the Receiver, annotated as 'Channel estimation initiation confirmation'. The Receiver sends MCE_ProbeRequest.ind or ACK (ACK_CE_CTRL) to the Transmitter, annotated as 'PROBE frame request'. The Transmitter sends PROBE frame to the Receiver, which responds with MCE_ProbeRequest.ind or ACK (ACK_CE_CTRL). The Transmitter sends another PROBE frame to the Receiver. The Receiver then sends User data transmission (BMAT_ID=X) to the Transmitter, followed by an Acknowledgment for ARQ. The Receiver sends MCE_ParamUpdate.req (BMAT_ID=Y, ...) to the Transmitter. The Transmitter sends User data transmission (BMAT_ID=X) to the Receiver, followed by an Acknowledgment for ARQ. The Receiver sends MCE_ParamUpdate.cnf (BMAT_ID=Y, ...) to the Transmitter, annotated as 'Channel estimation completion (the transmitter and receiver are synchronized and BMAT_ID=X is released)'. The Transmitter sends User data transmission (BMAT_ID=Y) to the Receiver, followed by an Acknowledgment for ARQ. The Receiver sends MCE_ProbeSlotRelease.req to the Transmitter, annotated as 'Bandwidth release for PROBE frame transmission', which is sent to the Domain master. The Domain master returns MCE_ProbeSlotRelease.cnf to the Transmitter.](5a9cdc1fed33ae8fb871a8cd4d591729_img.jpg) + +``` + +sequenceDiagram + participant Transmitter node + participant Receiver node + participant Domain master + + Note left of Transmitter node: Dotted-lines indicate optional communications. + + Transmitter node->>Receiver node: User data transmission (BMAT_ID=X) + Receiver node-->>Transmitter node: Acknowledgment for ARQ + Note right of Receiver node: ... + Receiver node->>Transmitter node: MCE_Initiation.req + Note right of Receiver node: Channel estimation initiation + Transmitter node-->>Domain master: MCE_ProbeSlotAssign.req + Note right of Transmitter node: Bandwidth request for PROBE frame transmission + Domain master-->>Transmitter node: MCE_ProbeSlotAssign.cnf + Transmitter node->>Receiver node: MCE_Initiation.cnf + Note right of Transmitter node: Channel estimation initiation confirmation + Receiver node-->>Transmitter node: MCE_ProbeRequest.ind or ACK (ACK_CE_CTRL) + Note right of Receiver node: PROBE frame request + Transmitter node-->>Receiver node: PROBE frame + Receiver node-->>Transmitter node: MCE_ProbeRequest.ind or ACK (ACK_CE_CTRL) + Transmitter node-->>Receiver node: PROBE frame + Note right of Transmitter node: ... + Transmitter node->>Receiver node: User data transmission (BMAT_ID=X)1 + Receiver node-->>Transmitter node: Acknowledgment for ARQ + Receiver node->>Transmitter node: MCE_ParamUpdate.req (BMAT_ID=Y, ...) + Transmitter node->>Receiver node: User data transmission (BMAT_ID=X)2 + Receiver node-->>Transmitter node: Acknowledgment for ARQ + Receiver node->>Transmitter node: MCE_ParamUpdate.cnf (BMAT_ID=Y, ...) + Note right of Receiver node: Channel estimation completion +(the transmitter and receiver are synchronized and +BMAT_ID=X is released) + Transmitter node->>Receiver node: User data transmission (BMAT_ID=Y)3 + Receiver node-->>Transmitter node: Acknowledgment for ARQ + Receiver node-->>Domain master: MCE_ProbeSlotRelease.req + Note right of Receiver node: Bandwidth release for PROBE frame transmission + Domain master-->>Transmitter node: MCE_ProbeSlotRelease.cnf + +``` + +Sequence diagram for Receiver-initiated channel estimation. The diagram shows three participants: Transmitter node, Receiver node, and Domain master. The process starts with User data transmission (BMAT\_ID=X) from Transmitter to Receiver, followed by an Acknowledgment for ARQ. The Receiver then sends MCE\_Initiation.req to the Transmitter, which is annotated as 'Channel estimation initiation'. The Transmitter responds with MCE\_ProbeSlotAssign.req, annotated as 'Bandwidth request for PROBE frame transmission', which is sent to the Domain master. The Domain master returns MCE\_ProbeSlotAssign.cnf to the Transmitter, which then sends MCE\_Initiation.cnf to the Receiver, annotated as 'Channel estimation initiation confirmation'. The Receiver sends MCE\_ProbeRequest.ind or ACK (ACK\_CE\_CTRL) to the Transmitter, annotated as 'PROBE frame request'. The Transmitter sends PROBE frame to the Receiver, which responds with MCE\_ProbeRequest.ind or ACK (ACK\_CE\_CTRL). The Transmitter sends another PROBE frame to the Receiver. The Receiver then sends User data transmission (BMAT\_ID=X) to the Transmitter, followed by an Acknowledgment for ARQ. The Receiver sends MCE\_ParamUpdate.req (BMAT\_ID=Y, ...) to the Transmitter. The Transmitter sends User data transmission (BMAT\_ID=X) to the Receiver, followed by an Acknowledgment for ARQ. The Receiver sends MCE\_ParamUpdate.cnf (BMAT\_ID=Y, ...) to the Transmitter, annotated as 'Channel estimation completion (the transmitter and receiver are synchronized and BMAT\_ID=X is released)'. The Transmitter sends User data transmission (BMAT\_ID=Y) to the Receiver, followed by an Acknowledgment for ARQ. The Receiver sends MCE\_ProbeSlotRelease.req to the Transmitter, annotated as 'Bandwidth release for PROBE frame transmission', which is sent to the Domain master. The Domain master returns MCE\_ProbeSlotRelease.cnf to the Transmitter. + +G.9963(11)\_F8-1 + +Dotted-lines indicate optional communications. + +1 The transmitter can transmit data using the existing BMAT anytime during channel estimation process. + +2 1st user data transmission after MCE\_ParamUpdate.req may not use updated channel estimation parameters. + +3 The transmitter decides when to apply updated channel estimation parameters within a given constraint. + +**Figure 8-1 – Receiver-initiated channel estimation** + +##### 8.11.1.1.1 Channel estimation initiation + +The receiver initiates the channel estimation process by sending the transmitter an MCE\_Initiation.req message. + +The receiver shall select CE\_BAT\_GRP (*G*), which indicates the value of GRP\_ID (*G*) associated with the BATs to be updated (whenever two spatial streams are used, the same grouping applies to both streams). The receiver shall also select CE\_PR\_GRP, which indicates the value of precoding grouping (*PG*) associated with the precoding parameters to be updated. The receiver shall select CE\_STIME and CE\_ETIME, which determines the start and end time of the channel estimation window. During the rest of channel estimation process, the transmitter shall send PROBE frames inside this window. The receiver shall select CE\_BMAT\_ID from ones that are currently invalid. This value shall be used to differentiate multiple channel estimation processes being executed at the same time. The receiver may request PROBE frame transmission by setting CE\_PRB\_RQST field. The MCE\_PRB\_PARM field specifies parameters for the default PROBE frame. If the CE\_PRB\_RQST field is not set to one, parameters for the default PROBE frame shall be as follows: + +CE\_PR\_PRBTYPE = 10002; CE\_PR\_PRBFN = 00002; CE\_PR\_PRBSYM = 00112; CE\_PR\_PRBGI = 1112, CE\_PR\_APSD\_MAX = 31, CE\_PR\_APSD\_MAX\_EXT=0 and PRB\_BMAT\_ID = 11. + +The receiver may resend the MCE\_Initiation.req message, if it does not receive the MCE\_Initiation.cnf message within 200 ms. + +##### **8.11.1.1.2 Channel estimation bandwidth request** + +If the transmitter does not have transmit opportunities inside a given channel estimation window, it shall request the domain master to allocate bandwidth for PROBE frame transmission by sending MCE\_ProbeSlotAssign.req message. + +The transmitter shall provide the domain master the channel estimation identifier (i.e., CE\_BMAT\_ID, Transmitter\_ID and Receiver\_ID), channel estimation window (CE\_STIME and CE\_ETIME) and PROBE frame parameters (CE\_PRB\_PARM) as provided by MCE\_Initiation.req message. + +The transmitter shall provide the priority of the bandwidth request in the MCE\_ProbeSlotAssign.req message by setting the CE\_PRIORITY field to the highest priority of the user data traffic that the transmitter has to send to the specified receiver. + +The domain master shall confirm the bandwidth request by replying to the transmitter with an MCE\_ProbeSlotAssign.cnf indicating whether or not the request is granted within 100 ms after it receives the MCE\_ProbeSlotAssign.req message. + +The domain master should allocate bandwidth so that at least one PROBE frame with requested parameters can be transmitted during the channel estimation window. The additional TSs or TXOPs shall only be used for PROBE frame transmissions (see clause 8.8.4.1.1 of [ITU-T G.9961]). If the domain master has granted extra bandwidth for PROBE frame transmission, it should keep this bandwidth until it receives the bandwidth release request from the transmitter (see clause 8.11.1.1.8). + +If the transmitter does not receive the MCE\_ProbeSlotAssign.cnf message, it may resend the MCE\_ProbeSlotAssign.req message multiple times before it transmits the channel estimation initiation confirmation. + +##### **8.11.1.1.3 Channel estimation initiation confirmation** + +The transmitter shall confirm the channel estimation initiation request by sending the receiver an MCE\_Initiation.cnf message. + +The transmitter shall indicate whether it grants or rejects the channel estimation initiation request. The transmitter shall set CE\_BMAT\_ID to the value selected by the receiver in the MCE\_Initiation.req message. The transmitter shall finalize CE\_BAT\_GRP, which shall be equal to the one indicated by the receiver via channel estimation initiation request and CE\_PG\_GRP, which shall be larger than or equal to the one indicated by the receiver via channel estimation initiation request. + +The transmitter shall send an MCE\_Initiation.cnf message within 100 ms after it receives the MCE\_Initiation.req message. If the transmitter needs to request the bandwidth for PROBE frame transmission, the transmitter shall send an MCE\_Initiation.cnf message within 200 ms. + +##### **8.11.1.1.4 Request for PROBE frame transmission** + +Once a channel estimation initiation request has been confirmed, the receiver may request the transmitter to send additional PROBE frames by sending MCE\_ProbeRequest.ind message. + +The receiver can request specific parameters of the PROBE frame via the CE\_PRB\_PARM field of the MCE\_ProbeRequest.ind message. + +Alternatively, the receiver may request PROBE frames by using the ACK\_CE\_CTRL field in the PHY-frame header of an ACK frame addressed to the transmitter node (see clause 8.11.1.4). + +The receiver may not request PROBE frames at all if it uses other frames carrying payload (e.g., MSG, BMSG, BACK) to estimate the channel. + +##### **8.11.1.1.5 PROBE frame transmission** + +Upon reception of the request for PROBE frame transmission, the transmitter shall transmit PROBE frames as soon as possible as described in clause 8.11.1.4. + +##### **8.11.1.1.6 Channel estimation completion** + +At any time after channel estimation initiation request has been confirmed, the receiver may send the transmitter the outcome of channel estimation using the MCE\_ParamUpdate.req message. The transmitter shall confirm reception of the new parameters by replying with the MCE\_ParamUpdate.cnf message within 100 ms. + +Upon reception of the MCE\_ParamUpdate.req message, the transmitter shall incorporate the new channel estimation parameters (new BMATs, etc.) as soon as possible. + +If the transmitter does not receive a message that is related to channel estimation (i.e., MCE\_ProbeRequest.ind or MCE\_ParamUpdate.req), or does not receive a request for PROBE frame transmission via an ACK frame, within 200 ms after the channel estimation initiation request has been confirmed, it may send the receiver an MCE\_ParamUpdateRequest.ind message to request the receiver to resend the result of the specified channel estimation. + +If the transmitter does not receive either MCE\_ParamUpdate.req or MCE\_Cancellation.req within 400 ms after the channel estimation initiation request has been confirmed, it shall abort the channel estimation process. + +##### **8.11.1.1.7 Channel estimation cancellation** + +At any time after channel estimation initiation request has been confirmed, the receiver may cancel the channel estimation process using the MCE\_Cancellation.req message. The transmitter shall confirm receiving the cancellation request within 100 ms by replying with the MCE\_Cancellation.cnf message. If the receiver does not receive the MCE\_Cancellation.cnf message within 200 ms, it may resend the MCE\_Cancellation.req message. + +If the receiver does not receive either MCE\_ParamUpdate.cnf or MCE\_Cancellation.cnf within 400 ms after the channel estimation initiation request has been confirmed, it shall abort the channel estimation process and consider the CE\_BMAT ID as invalid (see clause 8.11.1.5). + +In this case, the channel estimation is finished without generating a new BMAT (i.e., new BATs and MAT). + +##### **8.11.1.1.8 Channel estimation bandwidth release** + +Upon reception of the MCE\_ParamUpdate.req or MCE\_Cancellation.req message, the transmitter shall request the domain master to release any bandwidth previously assigned for PROBE frame transmission by sending MCE\_ProbeSlotRelease.req message. + +The transmitter shall provide the domain master with the channel estimation identifier (i.e., CE\_BMAT\_ID, Transmitter\_ID and Receiver\_ID) and channel estimation window (CE\_STIME and CE\_ETIME) associated with the channel estimation process. + +The domain master shall confirm receiving the MCE\_ProbeSlotRelease.req message within 100 ms by replying with the MCE\_ProbeSlotRelease.cnf message. If the domain master does not receive a CE\_ProbeSlotRelease.req message from the transmitter within 800 ms after the bandwidth was assigned, it shall release the bandwidth allocated to the transmitter for PROBE frames. The domain master shall only release bandwidth additionally assigned to the transmitter for PROBE frame transmission for the associated channel estimation identifier. + +#### 8.11.1.2 Transmitter-requested channel estimation + +The following procedure describes the transmitter-requested channel estimation process: + +- 1) The transmitter requests channel estimation by sending the receiver MCE\_Request.ind message (channel estimation request, see clause 8.11.1.2.1). +- 2) The rest of the procedure is the same as described in clause 8.11.1.1 (step 1 through step 8). + +The transmitter may send frames carrying payload with the existing settings (e.g., any valid runtime BMAT or predefined BMAT) any time during this process. + +##### 8.11.1.2.1 Channel estimation request + +The transmitter triggers the channel estimation process by sending the receiver MCE\_Request.ind message. + +The transmitter can specify the channel estimation window (CE\_STIME and CE\_ETIME). In this case the receiver shall use the same channel estimation window as the transmitter requested in the MCE\_Initiation.req message. Otherwise, the receiver can determine the channel estimation window at its own discretion. + +The receiver shall respond to a MCE\_Request.ind message from the transmitter within 100 ms with either a MCE\_Initiation.req message or a MCE\_ParamUpdate.req message. + +If the transmitter does not receive either the MCE\_Initiation.req message or the MC\_ParamUpdate.req message within 200 ms after MCE\_Request.ind is sent, it may resend the channel estimation request message. + +#### 8.11.1.3 Shortened channel estimation processes + +##### 8.11.1.3.1 Unsolicited MCE\_ParamUpdate.req + +It is not required to exchange PROBE frames between transmitter and receiver in order to exchange a new BMAT between them. The receiver may send a new BMAT at any time to the transmitter by sending an MCE\_ParamUpdate.req message, provided that the BMAT\_ID is invalid at the time of sending the new BMAT. The receiver may use PROBE frames or other frames carrying payload (e.g., MSG, BMSG, BACK) transmitted to other nodes to estimate the channel. + +Upon receiving the MCE\_ParamUpdate.req message, the transmitter shall reply by sending the MCE\_ParamUpdate.cnf message within 100 ms indicating whether the transmitter adopts the new BMAT or rejects the new BMAT due to lack of resources. + +If the receiver does not receive MCE\_ParamUpdate.cnf within 200 ms, it may retry with the same or a different MCE\_ParamUpdate.req message. + +##### 8.11.1.3.2 Partial BMAT update + +The transmitter and receiver that communicate with each other by establishing a common runtime BMAT may update a portion of the BMAT at any time during its usage. The receiver may initiate the partial BMAT update (PBMU) by sending PBMU information in the management message. + +The process of partial BMAT update is described as follows: + +- 1) At any time during communication, the receiver may send the PBMU request for any valid BMAT used by the transmitter. The PBMU request contains the new valid BMAT\_ID (N\_BMAT\_ID), old BMAT\_ID (O\_BMAT\_ID) associated with the BMAT to be updated and bit allocation changes (see clause 8.11.1.3.2.1). +- 2) Upon reception of the PBMU request, the transmitter shall update the BMAT associated with the O\_BMAT\_ID and assign N\_BMAT\_ID to the updated BMAT and reply with the PBMU confirmation. After receiving the first frame carrying payload using the N\_BMAT\_ID, the receiver shall consider O\_BMAT\_ID as invalid (see clause 8.11.1.5). + +- 3) The receiver may send another PBMU request after confirming that the transmitter incorporated the previous PBMU request or after inferring that the previous PBMU request was lost. + +###### 8.11.1.3.2.1 PBMU request + +The receiver may send the PBMU request using the MCE\_PartialBmatUpdate.req message in which the receiver can request bit allocations, Tx port mapping allocations and precoding parameter changes for up to 1024 sub-carriers. Figure 8-2 illustrates an example of partial BAT update using this approach. Note that acknowledgement is disabled in this example. + +If the receiver does not receive MCE\_PartialBmatUpdate.cnf within 200 ms, it may retry with the same or a different MCE\_PartialBmatUpdate.req message. + +###### 8.11.1.3.2.2 PBMU confirmation + +Upon reception of the MCE\_PartialBmatUpdate.req message, the transmitter should incorporate the new channel estimation parameters as soon as possible and then send the MCE\_PartialBmatUpdate.cnf message to confirm the received MCE\_PartialBmatUpdate.req message within 100 ms. The receiver shall infer loss of the PBMU request if the PBMU confirmation is not received within 200 ms after it transmits MCE\_PartialBmatUpdate.req. The transmitter may switch to N\_BMAT\_ID before sending the MCE\_PartialBmatUpdate.cnf message. + +![Figure 8-2: Example of partial BMAT update using management message. The diagram shows a sequence of four MSG frames transmitted by a Transmitter node (CE source) to a Receiver node (CE destination). The frames are labeled from left to right: 1) MSG frame carrying user data with PRE, PFH, and Data (modulated with BMAT_ID=X). 2) MSG frame carrying user data / or MCE_PartialBmatUpdate.cnf with PRE, PFH, and Data / management (modulated with BMAT_ID=Y). 3) MSG frame carrying user data with PRE, PFH, and Data (modulated with BMAT_ID=Y). 4) MSG frame carrying user data with PRE, PFH, and Data (modulated with BMAT_ID=Y). Below the frames, the receiver node is shown with a Management frame (modulated with BMAT_ID=X) and a message label: MSG frame carrying MCE_PartialBmatUpdate.req (O_BMAT_ID=X, N_BMAT_ID=Y). Arrows indicate the flow of frames and the receiver's response.](9e26cd5584f423e1b2155fb341db579f_img.jpg) + +The diagram illustrates the sequence of frames for a partial BMAT update. The transmitter (CE source) sends four MSG frames. The first frame carries user data with BMAT\_ID=X. The second frame carries user data or an MCE\_PartialBmatUpdate.cnf message with BMAT\_ID=Y. The third and fourth frames carry user data with BMAT\_ID=Y. The receiver (CE destination) sends a Management frame with BMAT\_ID=X and a message label: MSG frame carrying MCE\_PartialBmatUpdate.req (O\_BMAT\_ID=X, N\_BMAT\_ID=Y). + +Figure 8-2: Example of partial BMAT update using management message. The diagram shows a sequence of four MSG frames transmitted by a Transmitter node (CE source) to a Receiver node (CE destination). The frames are labeled from left to right: 1) MSG frame carrying user data with PRE, PFH, and Data (modulated with BMAT\_ID=X). 2) MSG frame carrying user data / or MCE\_PartialBmatUpdate.cnf with PRE, PFH, and Data / management (modulated with BMAT\_ID=Y). 3) MSG frame carrying user data with PRE, PFH, and Data (modulated with BMAT\_ID=Y). 4) MSG frame carrying user data with PRE, PFH, and Data (modulated with BMAT\_ID=Y). Below the frames, the receiver node is shown with a Management frame (modulated with BMAT\_ID=X) and a message label: MSG frame carrying MCE\_PartialBmatUpdate.req (O\_BMAT\_ID=X, N\_BMAT\_ID=Y). Arrows indicate the flow of frames and the receiver's response. + +G.9963(11)\_F8-2 + +**Figure 8-2 – Example of partial BMAT update using management message** + +#### 8.11.1.4 Channel estimation using PROBE frames + +The receiver can request the transmitter for PROBE frame transmission at any time after registration without going through the channel estimation initiation process. + +To request PROBE frames, the receiver may use MCE\_ProbeRequest.ind messages or the ACK\_CE\_CTRL field in the PFH of an ACK frame (see clause 7.1.2.3.2.3.1). Upon reception of a request for PROBE frame transmission, the transmitter should transmit PROBE frames as soon as possible. + +If the receiver requests a PROBE frame through a specific management message, the transmitter shall transmit the PROBE frame using parameters selected by the receiver, that is, the parameters selected in the latest request for PROBE frame transmission (MCE\_ProbeRequest.ind) or channel estimation initiation (MCE\_Initiation.req). + +If the receiver requests a PROBE frame through an ACK frame, the transmitter shall use the default PROBE frame. The transmitter shall use the default PROBE frame for all ACK frame-based requests for PROBE frame transmission by the receiver regardless of the BAT\_ID. In this case, the transmitter may transmit PROBE frames anywhere in a MAC cycle, regardless of a particular channel estimation window associated with the BMAT\_ID under channel estimation. + +The parameters for the default PROBE frame are determined by the receiver through the MCE\_Initiation.req message as described in clause 8.11.2.1.1. Alternatively, they can be updated by setting a bit in the MCE\_ProbeRequest.ind message as described in Table 8-19. + +When a transmitter receives a request for PROBE frame transmission from a receiver while handling previous requests for PROBE frame transmission from the same receiver, it should ignore the new request if the requested parameters are the same as the old ones, regardless of the value of the BMAT\_ID under estimation. + +NOTE – The transmitter should try to cover as much of the channel estimation window as possible when generating PROBE frames. + +When the receiver requests a PROBE frame via ACK frames, it may request multiple times by sending multiple ACK frames by setting ACK\_CE\_CTRL until it receives the PROBE frame. The transmitter should ignore new requests for PROBE frame transmission coming from the receiver in order to avoid unnecessary PROBE frame transmissions. + +After PROBE frame transmissions, the receiver may send the outcome of channel estimation to the transmitter in case it is needed, using an unsolicited MCE\_ParamUpdate.req (clause 8.11.1.3.1) or a partial BMAT update (clause 8.11.1.3.2). + +A PROBE frame should be considered as having an MPDU priority equal to 7. + +##### 8.11.1.4.1 Channel estimation using PROBE frames transmitted by a node as requested by the domain master + +Since the domain master (DM) is in charge of the scheduling and is also aware of the routes between any two nodes of the domain, DM may allocate a special CFTXOP assigned to a single source node and a minimum user priority identified by the tuple (SID, PRI) (see clause 8.3.4 of [ITU-T G.9961]) with the value of PRI set by the DM where the assigned node shall transmit PROBE frames (if it has no data to transmit), which the neighbouring nodes can then use to estimate the SNR and measure throughput. This information can be useful for diagnostics. This allows measurement of SNRs and throughput even on the links that are not used for delivering traffic, where there is no need to generate and exchange BATs. + +This special CFTXOP is indicated by the DM setting the "TXOP Limitations" field in the "Additional TXOP attributes" descriptor set to 2 (see Table 8-65.1 of [ITU-T G.9961]) and the "Traffic Limitation" field in the "TXOP attributes" descriptor set to 0 (see Table 8-65 of [ITU-T G.9961]). + +The DM may allocate bandwidth to specific nodes (in the form of special TXOPs for probe transmissions, see clause 8.8.4.1.1 of [ITU-T G.9961]) so that at least one PROBE frame with default parameters can be transmitted during the channel estimation window of interest. These special TXOPs shall be used for PROBE frame transmissions unless there is data that needs to be transmitted by the node that is assigned the special TXOP. The node that is assigned this special TXOP shall: + +- transmit regular data traffic during the TXOP, if the node has data to transmit, or +- transmit PROBE frames if the node has no data to transmit. + +Probe frames shall be transmitted at the maximum power level that the node uses for data transmission. The DID in the PHY frame header of the probe frame shall be set to FF16. + +#### 8.11.1.5 BMAT\_ID maintenance + +The receiver is responsible for tracking the list of valid and invalid BMAT\_IDs. The receiver informs the transmitter of the valid BMAT\_IDs in the VALID\_BMAT\_ID field by sending an MCE\_BmatIdMaintain.ind message. The transmitter shall stop using BMAT\_IDs that are marked as invalid by the receiver as soon as possible. If all the BMAT\_IDs are marked as invalid, the transmitter may use RCM mode. In this case, the transmitter should use the parameters indicated in the MCE\_BmatIdMaintain.ind message. + +If a BMAT\_ID is marked as valid by the receiver but the transmitter does not have a BMAT (BATs and MAT) associated with it (e.g., the transmitter fails to receive MCE\_ParamUpdate.req), the transmitter shall send an MCE\_ParamUpdateRequest.ind message requesting the transmission of the BMAT. + +The receiver may instruct the transmitter to stop using a BMAT\_ID via the ACK\_CE\_CTRL field in the ACK frame (see clause 7.1.2.3.2.3.1). The transmitter shall then consider the BMAT\_ID as invalid. + +The receiver may invalidate a BMAT\_ID as part of the channel estimation cancellation process (see clause 8.11.1.1.7). + +#### 8.11.1.6 ACE symbol insertion + +MIMO transmission of MSG, BMSG and BACK PHY frame types where the payload is intended for ITU-T G.9963 receivers (i.e., case 4a in Table 7-1, indicated by the MIMO\_IND flag in the PFH set to one) and MIMO transmission of PROBE frames (PRBTYPE 10002) shall always include at least one ACE symbol in the frame. In this case, in addition to this ACE symbol, up to 6 additional ACE symbols may be attached. In all other MIMO transmission cases where the transmission includes payload (i.e., cases 4b, 5 and 6 in Table 7-1), up to 7 ACE symbols may be attached. + +The receiver may request the transmitter to attach up to 7 ACE symbols (see clause 7.1.2.1) at any time after registration by sending an MCE\_ACESymbols.ind message for case 4a in Table 7-1 (indicated by the MIMO\_IND flag in the PFH set to one) and a CE\_ACESymbols.ind message for cases 4b, 5 and 6 in Table 7-1. Within 100 ms after receiving this message, the transmitter shall attach ACE symbols as requested by the receiver to all frames sent to the receiver that are allowed to carry ACE symbols. The receiver may use the same procedure to change the number of ACE symbols. + +#### 8.11.1.7 Management message formats for channel estimation + +##### 8.11.1.7.1 Format of MCE\_ProbeSlotAssign.req + +The format of the MMPL of the MCE\_ProbeSlotAssign.req message shall be as shown in Table 8-4. + +**Table 8-4 – Format of the MMPL of the MCE\_ProbeSlotAssign.req message** + +| Field | Octet | Bits | Description | +|----------------|--------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmitter ID | 0 | [7:0] | The DEVICE_ID of the node requesting the bandwidth allocation for PROBE frame transmissions. | +| Receiver ID | 1 | [7:0] | The DEVICE ID of the receiver node in the channel estimation procedure. | +| CE_BMAT_ID | 2 | [4:0] | This field indicates the BMAT_ID associated with the runtime BMAT to be updated by channel estimation. It shall be formatted as shown in Table 7-3. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| CE_STIME | 3 | [7:0] | This field indicates time at which the transmitter can start PROBE frame transmissions and it shall be coded as shown in Table 8-98 of [ITU-T G.9961]. | +| CE_ETIME | 4 | [7:0] | This field indicates time at which the transmitter shall end PROBE frame transmissions and it shall be coded as shown in Table 8-99 of [ITU-T G.9961]. | +| CE_PRB_PARM | 5 to 9 | [39:0] | This field specifies a set of parameters for PROBE frame. It shall be coded as shown in Table 8-23. | + +**Table 8-4 – Format of the MMPL of the MCE\_ProbeSlotAssign.req message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|--------------------------------------------------------------------------------------------------------------------------| +| CE_PRIORITY | 10 | [2:0] | This field specifies the highest user priority of the traffic the transmitter has to transmit to the specified receiver. | +| Reserved | | [7:3] | Reserved by ITU-T (Note). | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### **8.11.1.7.2 Format of MCE\_ProbeSlotRelease.req** + +The format of the MMPL of the MCE\_ProbeSlotRelease.req message shall be as shown in Table 8-5. + +**Table 8-5 – Format of the MMPL of the MCE\_ProbeSlotRelease.req message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|--------------------------------------------------------------------------------------------------------------------------------------------------------| +| Transmitter ID | 0 | [7:0] | The DEVICE_ID of the node requesting the bandwidth allocation for PROBE frame transmissions. | +| Receiver ID | 1 | [7:0] | The DEVICE_ID of the receiver who initiated the channel estimation. | +| CE_BMAT_ID | 2 | [4:0] | This field indicates the BMAT_ID associated with the runtime BMAT to be updated by channel estimation. It shall be formatted as shown in Table 7-3. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| CE_STIME | 3 | [7:0] | This field indicates time at which the transmitter can start PROBE frame transmissions and it shall be coded as shown in Table 8-98 of [ITU-T G.9961]. | +| CE_ETIME | 4 | [7:0] | This field indicates time at which the transmitter shall end PROBE frame transmissions and it shall be coded as shown in Table 8-99 of [ITU-T G.9961]. | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### **8.11.1.7.3 Format of MCE\_ParamUpdate.req** + +The format of the MMPL of the MCE\_ParamUpdate.req message shall be as shown in Table 8-6. + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|-----------------|---------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| New BMAT ID | 0 and 1 | [4:0] | This field indicates the BMAT_ID associated with a new BMAT (CE_BMAT_ID). It shall be formatted as shown in Table 7-3. | +| Frequency range | | [7:5] | This field indicates the type of frequency range based on which the subsequent BAT entries are defined. It shall be formatted as shown in Table 7-10 of [ITU-T G.9960]. | +| CE_BAT_GRP | | [10:8] | This field indicates the BAT grouping (G) associated with the new BATs, and determined at the channel estimation initiation confirmation. It shall be formatted as shown in Table 8-7. | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|-------------------------------------------|-------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| MIMO mode indicator | | [12:11] | This field indicates the usage of one of the following MIMO modes, for the BMAT_ID associated with the new BMAT (CE_BMAT_ID) (Note 10):
0 – Mode 0
1 – Mode 1
2 – Mode 2
3 – Reserved by ITU-T
See clause 8.23.2.2 for a description of the above modes. | +| BAT update indicator | | [13] | 0, when the BATs of SS 1 and SS 2 are not updated in the message, i.e., when the BAT fields, $B_1^{(1)}, \dots, B_Z^{(1)}$ and $B_1^{(2)}, \dots, B_Z^{(2)}$ are not present in the message.
1, when the BATs of SS 1 and SS 2 are updated in the message, i.e., when the BAT fields are present in the message.
Z is defined in the TIDX MAX field. | +| Precoding feedback update indicator | | [14] | 0, when the precoding parameters are not updated in the message, i.e., when the precoding parameters fields, $P_{1,0}, P_{1,\phi}, \dots, P_{K,0}$ and $P_{K,\phi}$ are not present in the message.
1, the precoding parameters are updated in the message, i.e., when the precoding parameters fields are present in the message.
This field shall be set to 0 in case the "MIMO mode indicator" field is set to 0.
K is defined in the TIDX max field. | +| Precoding feedback quantization indicator | | [15] | 0, when $P_{i,0}$ and $P_{i,\phi}$ are quantized as 4-bit values.
1, when $P_{i,0}$ and $P_{i,\phi}$ are quantized as 8-bit values.
Whenever the "Precoding feedback update indicator" field is set to 0 this field shall be ignored by the receiver of the message. | +| CE_PR_GRP | 2 | [2:0] | This field indicates the precoding grouping (PG) associated with the precoding feedback update indicator and the feedback parameters $P_{i,j}$ , and determined at the channel estimation initiation confirmation. It shall be formatted as shown in Table 8-7 – Format of the CE_PR_GRP.
Whenever the "Precoding feedback update indicator" field is set to 0 this field shall be ignored by the receiver of the message. | +| BAT_COMPRESSION | | 3 | This bit indicates if a run-length compression mechanism is used for conveying the BAT information (fields $B_1^{(1)}$ to $B_Z^{(1)}$ and fields $B_1^{(2)}$ to $B_Z^{(2)}$ ).
When this bit is set to zero, no run-length compression mechanism is used for BAT compression.
When this bit is set to one, a run-length compression mechanism is used for BAT compression.
This bit shall only be set to one if the BMAT compression field (see Table 8-0) is also set to one. | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|----------------------------|---------|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| PRECODING_COMPRESSION | | 4 | This bit indicates if a run-length compression mechanism is used for conveying the precoding information (fields $P_{1,0}$ to $P_{K,0}$ and fields $P_{1,\phi}$ to $P_{K,\phi}$ ).
When this bit is set to zero, no run-length compression mechanism is used for precoding compression.
When this bit is set to one, a run-length compression mechanism is used for precoding compression.
This bit shall only be set to one if the BMAT compression field (see Table 8-0) is also set to one. | +| NUM_VALID_DUR_EXT | | [6:5] | This field contains the extended bits of NUM_VALID_DUR, and they are appended and used for the MSB of NUM_VALID_DUR. With this extension, the valid range of values for NUM_VALID_DUR is from 0 ( $V=1$ ) to 31 ( $V=32$ ) (Note 16). | +| APSD_MAX_EXT | | [7] | This field is the value of APSD_MAX_EXT in the PHY-frame header associated with the new BMAT. This field shall be formatted as shown in clause 7.1.2.3.2.2.25 of [ITU-T G.9960] (Note 15). | +| VALID_BMAT_ID | 3 and 4 | [15:0] | This field contains a bitmap indicating which runtime BMATs are valid (including the New BMAT ID) for this node (SID) when receiving from the destination node (DID). Each bit is associated with one runtime BMAT. Bit 0 of the VALID_BMAT_ID shall be set to one if runtime BMAT_ID 16 is valid. Bit 11 of the VALID_BMAT_ID shall be set to one if runtime BMAT_ID 27 is valid. | +| NUM_TX_AVAIL_BMATS_NO_PREC | 5 | [3:0] | This field contains the number of available runtime BMATs, assuming $G = 1$ and no precoding, that this node (SID) can support when transmitting to the destination node (DID). Valid values are from 0 to 12. | +| NUM_TX_AVAIL_BMATS_PREC | | [7:4] | This field contains the number of available runtime BMATs, assuming $G = 1$ and $PG = 1$ (with the precoding parameters quantized to 8 bits), that this node (SID) can support when transmitting to the destination node (DID). Valid values are from 0 to 12. | +| New block size | 6 | [1:0] | This field indicates the proposed BLKSZ associated with the new BMAT. It shall be formatted as shown in Table 7-7 of [ITU-T G.9960] (Note 2). | +| New FEC rate | | [4:2] | This field indicates the proposed FEC_RATE associated with the new BMAT. It shall be formatted as shown in Table 7-12 of [ITU-T G.9960] (Note 3). | +| New GI | | [7:5] | This field indicates the proposed GI_ID associated with the new BMAT. It shall be formatted as shown in Table 7-14 of [ITU-T G.9960] (Note 4). | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|----------------------------------------|-------------------------------------|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| APSD_MAX | 7 | [4:0] | This field is the value of APSD_MAX in the PHY-frame header associated with the new BMAT. This field shall be formatted as shown in clause 7.1.2.3.2.2.11 (Note 15). | +| NUM_VALID_DURATION | | [7:5] | This field indicates the number of valid durations specified for the new BMAT ( V ). The valid range of values for this field is from 0 ( V =1) to 7 ( V =8) without extension (Note 5). | +| CE_TIME 1 | 8 | [7:0] | This field indicates the start time of the first duration in which the new BMAT is valid. It shall be formatted as shown in Table 8-98 of [ITU-T G.9961]. | +| CE_ETIME 1 | 9 | [7:0] | This field indicates the end time of the first duration in which the new BMAT is valid. It shall be formatted as shown in Table 8-99 of [ITU-T G.9961]. | +| ... | ... | ... | ... | +| CE_TIME V | 2 V +6 | [7:0] | This field indicates the start time of the last duration in which the new BAT is valid. It shall be formatted as shown in Table 8-98 of [ITU-T G.9961]. | +| CE_ETIME V | 2 V +7 | [7:0] | This field indicates the end time of the last duration in which the new BMAT is valid. It shall be formatted as shown in Table 8-99 of [ITU-T G.9961]. | +| TIDX MIN for Profile 1 OFBs | (2 V +8) to (2 V +10) | [11:0] | 12-bit unsigned integer indicating the minimum of:
1) the first sub-carrier index of the first BAT group to which non-zero bits are assigned in spatial stream 1, and
2) the first sub-carrier index of the first BAT group to which non-zero bits are assigned in spatial stream 2.
It shall be an integer multiple of G (Note 6).
The value of this field shall be associated with the BMAT and shall be used during partial BMAT updates (see Table 8-9). | +| TIDX MAX for Profile 1 OFBs | | [23:11] | 12-bit unsigned integer indicating the maximum of:
1) the first sub-carrier index of the last BAT group to which non-zero bits are assigned in spatial stream 1, and
2) the first sub-carrier index of the last BAT group to which non-zero bits are assigned in spatial stream 2.
It shall be an integer multiple of G (Note 6) and if bit-loading grouping is used ( G >1) shall meet: $\text{TIDX}_{\text{MAX}} + G - 1 \leq \text{StopSubCarrier}$ , where StopSubCarrier is specified in Table 8-16.6 ("Bandplan Info Capability Value field") of [ITU-T G.9961].
Let W denote the number of BAT entries, which is $(\text{TIDX}_{\text{MAX}} - \text{TIDX}_{\text{MIN}})/G + 1$ .
Let Z denote the smallest integer larger than or equal to W /2.
Let K denote the number of precoding entries (i.e., the number of precoding groups), which is the smallest integer larger than or equal to $(\text{TIDX}_{\text{MAX}} + G - \text{TIDX}_{\text{MIN}})/PG$ . | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|-------------------------------|-----------|----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| B 1 (1) | 2V+11 | [3:0] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 1 for sub-carrier indices from TIDX MIN to TIDX MIN + G – 1 (Notes 6, 7).
This field only exists if BAT_COMPRESSION field is set to 0. | +| | | [7:4] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 1 for sub-carrier indices from TIDX MIN + G to TIDX MIN + 2G – 1 (Notes 6, 7, 8).
This field only exists if BAT_COMPRESSION field is set to 0. | +| ... | ... | ... | ... | +| B Z (1) | 2V+10 + Z | [3:0] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 1 for sub-carrier indices from TIDX MAX – G to TIDX MAX – 1 if W is even, or to sub-carrier indices TIDX MAX to TIDX MAX + G – 1 if W is odd (Notes 6, 7).
This field only exists if BAT_COMPRESSION field is set to 0. | +| | | [7:4] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 1 for sub-carrier indices from TIDX MAX to TIDX MAX + G – 1 if W is even (Notes 6, 7, 9).
This field only exists if BMAT_COMPRESSION field is set to 0. | +| COMPRESSED_BAT (1) | variable | variable | Compressed information that includes the Z fields B i (1) .
This field shall be filled using the mechanism described in clause 8.23 of [ITU-T G.9961] with a Pattern field formatted as field B i (1) of this message (N=8).
This field only exists if BAT_COMPRESSION field is set to one. | +| B 1 (2) | variable | [3:0] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 2 for sub-carrier indices from TIDX MIN to TIDX MIN + G – 1 (Notes 6, 7).
This field only exists if BAT_COMPRESSION field is set to 0. | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|----------------------------|----------|----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | [7:4] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 2 for sub-carrier indices from $TIDX_{MIN} + G$ to $TIDX_{MIN} + 2G - 1$ (Notes 6, 7, 8).
This field only exists if BAT_COMPRESSION field is set to 0. | +| ... | ... | ... | ... | +| $B_Z^{(2)}$ | variable | [3:0] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 2 for sub-carrier indices from $TIDX_{MAX} - G$ to $TIDX_{MAX} - 1$ if W is even, or to sub-carrier indices $TIDX_{MAX}$ to $TIDX_{MAX} + G - 1$ if W is odd (Notes 6, 7).
This field only exists if BAT_COMPRESSION field is set to 0. | +| | | [7:4] | This field shall be present if and only if the "BAT update indicator" field is set to one. It shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 2 for sub-carrier indices from $TIDX_{MAX}$ to $TIDX_{MAX} + G - 1$ if W is even (Notes 6, 7, 9).
This field only exists if BAT_COMPRESSION field is set to 0. | +| COMPRESSED_B
$AT^{(2)}$ | variable | variable | Compressed information that includes the Z fields $B_i^{(2)}$ .
This field shall be filled using the mechanism described in clause 8.23 of [ITU-T G.9961] with a Pattern field formatted as field $B_i^{(2)}$ of this message (N=8).
This field only exists if BAT_COMPRESSION field is set to one. | +| $P_{1,\theta}$ | variable | variable | This field shall be present if and only if the "precoding parameters update indicator" field is set to one (Note 13). It shall be represented as a 4-bit (Note 12) or 8-bit unsigned integer indicating the angle $\theta$ which is one of the parameters of the precoding matrix assigned to the first group of PG sub-carriers, having sub-carrier indices $TIDX_{MIN}$ to $TIDX_{MIN} + PG - 1$ . The value of $\theta$ , in units of radians, is equal to either (based on the Precoding feedback quantization indicator field):
$\theta = \pi(2P_\theta + 1)/64$ where: $P_\theta = P_{1,\theta} = 0 \dots 15$ (4-bit quantization), or
$\theta = \pi(2P_\theta + 1)/1024$ where: $P_\theta = P_{1,\theta} = 0 \dots 255$ (8-bit quantization).
This field only exists if PRECODING_COMPRESSION field is set to 0. | +| ... | ... | ... | ... | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|----------------|----------|----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $P_{K,\theta}$ | variable | variable | This field shall be present if and only if the "precoding parameters update indicator" field is set to one (Note 13). It shall be represented as a 4-bit (Note 12) or 8-bit unsigned integer indicating the angle $\theta$ which is one of the parameters of the precoding matrix assigned to the last group of $PG$ sub-carriers, having sub-carrier indices $TIDX_{MIN} + PG \times (K-1)$ to $TIDX_{MIN} + PG - 1 + PG \times (K-1)$ . The value of $\theta$ , in units of radians, is equal to either (based on the Precoding feedback quantization indicator field):
  • \theta = \pi(2P_\theta + 1)/64 where: P_\theta = P_{K,\theta} = 0 \dots 15 (4-bit quantization), or
  • \theta = \pi(2P_\theta + 1)/1024 where: P_\theta = P_{K,\theta} = 0 \dots 255 (8-bit quantization).
This field only exists if PRECODING_COMPRESSION field is set to 0. | +| COMPRESSED_θ | variable | variable | Compressed information that includes the $K$ fields $P_{i,\theta}$ . This field shall be filled using the mechanism described in clause 8.23 of [ITU-T G.9961] with a Pattern field formatted as field $P_{i,\theta}$ of this message ( $N=4$ or $N=8$ , depending on the value of the field Precoding feedback quantization indicator). This field only exists if PRECODING_COMPRESSION field is set to one. | +| $P_{1,\phi}$ | variable | variable | This field shall be present if and only if the "precoding parameters update indicator" field is set to one (Note 13). It shall be represented as a 4-bit (Note 12) or 8-bit unsigned integer indicating the angle $\phi$ which is one of the parameters of the precoding matrix assigned to the first group of $PG$ sub-carriers, having sub-carrier indices $TIDX_{MIN}$ to $TIDX_{MIN} + PG - 1$ . The value of $\phi$ , in units of radians, is equal to either (based on the Precoding feedback quantization indicator field) (Note 11):
  • \phi = \pi(2P_\phi + 1)/16 where: P_\phi = P_{1,\phi} = 0 \dots 15 (4-bit quantization), or
  • \phi = \pi(2P_\phi + 1)/256 where: P_\phi = P_{1,\phi} = 0 \dots 255 (8-bit quantization).
This field only exists if PRECODING_COMPRESSION field is set to 0. | +| ... | ... | ... | ... | +| $P_{K,\phi}$ | variable | variable | This field shall be present if and only if the "precoding parameters update indicator" field is set to one (Note 13). It shall be represented as a 4-bit (Note 12) or 8-bit unsigned integer indicating the angle $\phi$ which is one of the parameters of the precoding matrix assigned to the last group of $PG$ sub-carriers, having sub-carrier indices $TIDX_{MIN} + PG \times (K-1)$ to $TIDX_{MIN} + PG - 1 + PG \times (K-1)$ . The value of $\phi$ , in units of radians, is equal to either (based on the Precoding feedback quantization indicator field) (Note 11): | + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|--------------|----------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | |
  • \phi = \pi(2P_\phi + 1)/16 where: P_\phi = P_{K,\phi} = 0 \dots 15 (4-bit quantization), or
  • \varphi = \pi(2P_\phi + 1)/256 where: P_\phi = P_{K,\phi} = 0 \dots 255 (8-bit quantization).

This field only exists if PRECODING_COMPRESSION field is set to 0.

| +| COMPRESSED_φ | variable | variable |

Compressed information that includes the K fields P_{i,\phi}. This field shall be filled using the mechanism described in clause 8.23 of [ITU-T G.9961] with a Pattern field formatted as field P_{i,\phi} of this message (N=4 or N=8, depending on the value of the field Precoding feedback quantization indicator).

This field only exists if PRECODING_COMPRESSION field is set to one.

| + +NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +NOTE 2 – The transmitter shall use the proposed block size or larger block size for a new connection. Once the block size is selected for a connection, it shall not be changed throughout the lifetime of the connection (clause 8.1.3.2 of [ITU-T G.9960]). + +NOTE 3 – The transmitter shall use the proposed FEC rate or lower FEC rate. + +NOTE 4 – The transmitter shall use the proposed GI or longer GI value. + +NOTE 5 – A new BMAT shall only be used over specified non-overlapping durations (up to 8) within a MAC cycle, defined by CE\_STIMEi and CE\_ETIMEi without extension. + +NOTE 6 – Sub-carrier index represents the physical index (clause 7.1.4.1). All BMATs entries outside [TIDXMIN, TIDXMAX + $G - 1$ ] shall be considered as unloaded. + +NOTE 7 – If a sub-carrier is not loaded, the field shall be set to 0 or 15. + +NOTE 8 – If $W = 1$ , this field shall be set to zero. + +NOTE 9 – If $W$ is an odd number, this field shall be set to zero. + +NOTE 10 – The Tx port mapping matrix (*TPM*) that shall be used by each sub-carrier is indicated by the coding of bits in the BATs assigned to the two spatial streams of the sub-carrier, and the MIMO mode indicator, according to Table 8-2. + +NOTE 11 – In the powerline medium, the cyclic shift introduces a decrement of $2*\pi*T_{CS}*F_{SC}=0.098175$ radians (approximation of $\pi/32$ radians) to the angle $\varphi$ from one sub-carrier to the next When $PG > 1$ the value of $P_\phi$ shall be referred to the lowest frequency sub-carrier in the group. The transmitter shall calculate the value of $\varphi$ for each sub-carrier of the group $i$ ( $i = 0 \dots PG - 1$ ) as: + +- $\varphi = \pi(2P'_\phi + 1)/16$ , where $P'_\phi = (4P_\phi - i)/4$ for the case of 4 bit quantization +- $\varphi = \pi(2P'_\phi + 1)/256$ , where $P'_\phi = P_\phi - 4i$ for the case of 8 bit quantization. + +NOTE 12 – For 4-bit values, 2 values are packed into each octet with 4 LSBs corresponding to the lower sub-carrier index. If K is odd, the 4 MSBs of the octet containing $P_{K,\theta}$ and $P_{K,\phi}$ shall be set to zero. + +NOTE 13 – Precoding parameters are reported for all of the precoding groups, even those that include sub-carriers that are associated with Tx port mapping with no precoding. + +NOTE 14 – The constant phase rotation (see Note 11) from a group to the next group shall be removed from the field $P_{i,\phi}$ before applying the compression mechanism. The first group (of the K groups) is considered as the reference (no constant phase removal needed). + +NOTE 15 – It is the responsibility of the receiver to set APSD\_MAX and APSD\_MAX\_EXT taking into account the PSD limitations and capabilities of the transmitter that are known to the receiver (see clause 7.1.5 of [ITU-T G.9960]). + +**Table 8-6 – Format of the MMPL of the MCE\_ParamUpdate.req message** + +| Field | Octet | Bits | Description | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|------|-------------| +| NOTE 16 – A new BAT shall only be used over specified non-overlapping durations (up to 32) within a MAC cycle, defined by CE_STIME i and CE_ETIME i with extension of NUM_VALID_DUR. | | | | + +**Table 8-7 – Format of the CE\_BAT\_GRP** + +| BAT_GRP_ID value
(b 10 b 9 b 8 ) | Description | +|----------------------------------------------------------------------|----------------------------------------------------------| +| 000 | Default – No BAT sub-carrier grouping ( $G = 1$ ) | +| 001 | BAT sub-carrier grouping of 2 sub-carriers ( $G = 2$ ) | +| 010 | BAT sub-carrier grouping of 4 sub-carriers ( $G = 4$ ) | +| 011 | BAT sub-carrier grouping of 8 sub-carriers ( $G = 8$ ) | +| 100 | BAT sub-carrier grouping of 16 sub-carriers ( $G = 16$ ) | +| 101 to 111 | Reserved by ITU-T | + +**Table 8-8 – Format of the CE\_PR\_GRP** + +| PR_GRP_ID value
(b 2 b 1 b 0 ) | Description | +|--------------------------------------------------------------------|-----------------------------------------------------------------| +| 000 | Default – No precoding sub-carrier grouping ( $PG = 1$ ) | +| 001 | Precoding sub-carrier grouping of 2 sub-carriers ( $PG = 2$ ) | +| 010 | Precoding sub-carrier grouping of 4 sub-carriers ( $PG = 4$ ) | +| 011 | Precoding sub-carrier grouping of 8 sub-carriers ( $PG = 8$ ) | +| 100 | Precoding sub-carrier grouping of 16 sub-carriers ( $PG = 16$ ) | +| 101 to 111 | Reserved by ITU-T | + +##### 8.11.1.7.4 Format of MCE\_ParamUpdateRequest.ind + +The format of the MMPL of the MCE\_ParamUpdateRequest.ind message shall be as shown in Table 8-9. + +**Table 8-9 – Format of the MMPL of the MCE\_ParamUpdateRequest.ind message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Requested BMAT ID | 0 | [4:0] | This field indicates the BMAT_ID for which the transmitter requests retransmission of the channel estimation result. It shall be formatted as shown in Table 7-3. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### 8.11.1.7.5 Format of MCE\_PartialBmatUpdate.req + +The format of the MMPL of the MCE\_PartialBmatUpdate.req message shall be as shown in Table 8-10. + +**Table 8-10 – Format of the MMPL of the MCE\_PartialBmatUpdate.req message** + +| Field | Octet | Bits | Description | +|-------------------------------------------|---------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| O_BMAT_ID | 0 | [4:0] | This field indicates the BMAT_ID associated with the BMAT to be updated by the PBMU request. It shall be formatted as shown in Table 7-3. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| N_BMAT_ID | 1 | [4:0] | This field indicates the BMAT_ID associated with the BMAT updated by the PBMU request. It shall be formatted as shown in Table 7-3. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| NUM_BAT_ENT for Profile 1 OFBs | 2 and 3 | [9:0] | This field indicates the number of BAT entries to be updated ( V ). The valid range of this field is from 0 ( V =1) to 1023 ( V =1024).
For Profile 2 OFBs, this field shall be set to zero. | +| Reserved | | [15:10] | Reserved by ITU-T (Note). | +| NUM_PG_ENT | 4 and 5 | [9:0] | This field indicates the number of precoding group entries to be updated ( Q ). The valid range of this field is from 0 ( Q =1) to 1023 ( Q =1024).
Whenever the "Precoding feedback update indicator" field is set to 0 this field shall be ignored by the receiver of the message. | +| BAT SS 1 update indicator | | [10] | 0, when the BAT of SS 1 is not updated in the message, i.e., the BAT fields, $B_{T1}^{(1)}, \dots, B_{Tv}^{(1)}$ (including the reserved fields in the relevant octets) are not present in the message
1, when the BAT of SS 1 is updated in the message, i.e., the BAT fields are present in the message. | +| BAT SS 2 update indicator | | [11] | 0, when the BAT of SS 2 is not updated in the message, i.e., the BAT fields, $B_{T1}^{(2)}, \dots, B_{Tv}^{(2)}$ (including the reserved fields in the relevant octets) are not present in the message
1, when the BAT of SS 2 is updated in the message, i.e., the BAT fields are present in the message. | +| Precoding feedback update indicator | | [12] | 0, when the precoding parameters are not updated in the message, i.e., the precoding parameters fields, $PT_1, P_{0,PT1}, P_{\phi,PT1}, \dots, PT_Q, P_{0,PTQ}, P_{\phi,PTV}$ are not present in the message
1, when the precoding parameters are updated in the message, i.e., the precoding parameters fields are present in the message
This field shall be set to 0 in case the "MIMO mode indicator" field associated with the O_BMAT_ID is set to 0. | +| Precoding feedback quantization indicator | | [13] | 0, when $P_{i,0}$ and $P_{i,\phi}$ are quantized as 4-bit values
1, when $P_{i,0}$ and $P_{i,\phi}$ are quantized as 8-bit values
Whenever the "Precoding feedback update indicator" field is set to 0 this field shall be ignored by the receiver of the message.
The quantization value shall be the same as one associated with O_BMAT_ID. | +| Reserved | | [15:14] | Reserved by ITU-T (Note). | + +**Table 8-10 – Format of the MMPL of the MCE\_PartialBmatUpdate.req message** + +| Field | Octet | Bits | Description | +|----------------------------------------|----------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 2SS BAT entry descriptor[ V ] | variable | [23:0] | This field shall be present if and only if both the fields "BAT SS 1 update indicator" and "BAT SS 2 update indicator" are set to one. It shall be formatted as shown in Table 8-10. | +| 1SS BAT entry descriptor[ V ] | variable | [15:0] | This field shall be present if and only if exactly one of the fields "BAT SS 1 update indicator" and "BAT SS 2 update indicator" is set to one. It shall be formatted as shown in Table 8-11. | +| Precoding entry descriptor[ Q ] | variable | variable | This field shall be present if and only if the "precoding parameters update indicator" field is set to one. It shall be formatted as shown in Table 8-12. | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +**Table 8-11 – Format of the 2SS BAT entry descriptor** + +| Field | Octet | Bits | Description | +|----------------|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $T_i$ | 0 to 2 | [11:0] | This field shall be represented as a 12-bit unsigned integer indicating the sub-carrier index (Note 1). It shall be an integer multiple of $G$ .
$T_i = TID\text{Xmin} + \max(G, PG) * I$ ; where $I$ is an integer (Note 2) and $TID\text{Xmin}$ is the value associated with the $O\_BMAT\_ID$ (see Table 8-9). | +| $B_{Ti}^{(1)}$ | | [15:12] | This field shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 1 for sub-carrier indices from $T_i$ to $T_i + G - 1$ . | +| $B_{Ti}^{(2)}$ | | [19:16] | This field shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream 2 for sub-carrier indices from $T_i$ to $T_i + G - 1$ . | +| Reserved | | [23:20] | Reserved by ITU-T (Note 3). | + +NOTE 1 – Sub-carrier index represents the physical index (see clause 7.1.4.1). +NOTE 2 – Values of $T_i$ less than $TID\text{Xmin}$ may be selected by using a negative value of $I$ . +NOTE 3 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +**Table 8-12 – Format of the 1SS BAT entry descriptor** + +| Field | Octet | Bits | Description | +|----------------|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| $T_i$ | 0 to 1 | [11:0] | This field shall be represented as a 12-bit unsigned integer indicating the sub-carrier index (Note 1).
$T_i = TID\text{Xmin} + \max(G, PG) * I$ ; where $I$ is an integer (Note 2) and $TID\text{Xmin}$ is the value associated with the $O\_BMAT\_ID$ (see Table 8-5). | +| $B_{Ti}^{(k)}$ | | [15:12] | This field shall be represented as a 4-bit unsigned integer indicating the number of bits assigned to spatial stream $k$ for sub-carrier indices from $T_i$ to $T_i + G - 1$ .
The value of $k$ is:
1 if the field "BAT SS 1 update indicator" is set to one.
2 if the field "BAT SS 2 update indicator" is set to one. | + +NOTE 1 – Sub-carrier index represents the physical index (see clause 7.1.4.1). +NOTE 2 – Values of $T_i$ less than $TID\text{Xmin}$ may be selected by using a negative value of $I$ . + +**Table 8-13 – Format of the Precoding entry descriptor** + +| Field | Octet | Bits | Description | +|--------------------------------|----------|----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| PT i | 0 and 1 | [11:0] | This field shall represent 12-bit unsigned integer indicating the sub-carrier index (Note 1).
PT i =TIDXmin+PG*I; where I is an integer (Note 2) and TIDXmin is the value associated with the O_BMAT_ID (see Table 8-5). | +| Reserved | | [15:12] | Reserved by ITU-T. | +| P θ, PTi | Variable | variable | This field shall represent a 4-bit or 8-bit unsigned integer indicating the angle θ, which is one of the parameters of the precoding matrix assigned to a group of PG sub-carriers with indices PT i to PT i +PG-1. The value of θ, in units of radians, is equal to either (based on the Precoding feedback quantization indicator field) (Note 3):
  • • \theta = \pi(2P_\theta + 1)/64 where: Pθ= Pθ, PTi = 0...15 (4-bit quantization), or
  • • \theta = \pi(2P_\theta + 1)/1024 where: Pθ= Pθ, PTi = 0...255 (8-bit quantization).
| +| P φ, PTi | Variable | Variable | This field shall represent a 4-bit or 8-bit unsigned integer indicating the angle φ, which is one of the parameters of the precoding matrix assigned to a group of PG sub-carriers with indices PT i to PT i +PG-1. The value of φ, in units of radians, is equal to either (based on the Precoding feedback quantization indicator field) (Notes 3, 4):
  • • \phi = \pi(2P_\phi + 1)/16 where: Pφ= Pφ, PTi = 0...15 (4-bit quantization), or
  • • \phi = \pi(2P_\phi + 1)/256 where: Pφ= Pφ, PTi = 0...255 (8-bit quantization).
| + +NOTE 1 – Sub-carrier index represents the physical index (see clause 7.1.4.1). + +NOTE 2 – Values of PT less than TIDXmin may be selected by using a negative value of I. + +NOTE 3 – For 4-bit quantization, the size of precoding entry descriptor is 3 bytes. For 8-bit quantization, the size of precoding entry descriptor is 4 bytes. + +NOTE 4 – In the powerline medium, the cyclic shift introduces a decrement of $2\pi T_{CS} F_{SC} = 0.098175$ radians (approximation of $\pi/32$ radians) to the angle φ from one sub-carrier to the next When $PG > 1$ the value of Pφ shall be referred to the lowest frequency sub-carrier in the group. The transmitter shall calculate the value of φ for each sub-carrier of the group $i$ ( $i = 0 \dots PG-1$ ) as: + +- $\phi = \pi(2P'_\phi + 1)/16$ , where $P'_\phi = (4P_\phi - i)/4$ for the case of 4 bit quantization. +- $\phi = \pi(2P'_\phi + 1)/256$ , where $P'_\phi = P_\phi - 4i$ for the case of 8 bit quantization. + +##### 8.11.1.7.6 Format of MCE\_ACESymbols.ind + +The format of the MMPL of the MCE\_ACESymbols.ind message shall be as shown in Table 8-13. + +**Table 8-14 – Format of the MMPL of the MCE\_ACESymbols.ind message** + +| Field | Octet | Bits | Description | +|-------------|-------|-------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| ACE symbols | 0 | [2:0] | This field indicates the number of ACE symbols added to the beginning of the payload of all frames that are allowed to carry ACE symbols where the MIMO_IND flag in the PFH is set to one. It shall be formatted as shown in Table 7-16 of [ITU-T G.9960]. For MIMO transmission, the valid range is 1 to 7 (in MIMO transmission at least one ACE symbol is attached, as described in clause 7.1.4.4.4.3). | +| Reserved | | [7:3] | Reserved by ITU-T (Note). | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +##### 8.11.1.7.7 Format of MCE\_ProbeSlotAssign.cnf + +The format of the MMPL of the MCE\_ProbeSlotAssign.cnf message shall be as shown in Table 8-15. + +**Table 8-15 – Format of the MMPL of the MCE\_ProbeSlotAssign.cnf message** + +| Field | Octet | Bits | Description | +|----------------|-------|-------|----------------------------------------------------------------------------------------------------------------| +| Transmitter ID | 0 | [7:0] | The DEVICE_ID of the node requesting the bandwidth allocation for PROBE frame transmissions. | +| Receiver ID | 1 | [7:0] | The DEVICE_ID of the receiver that initiated the channel estimation procedure. | +| CE_BMAT_ID | 2 | [4:0] | This field indicates the BMAT_ID associated with the runtime BMAT to which bandwidth was required for probing. | +| Request Status | | [7:5] | 0 – Bandwidth request is confirmed (Note)
1 – Request is rejected
2 to 7 – Reserved by ITU-T. | + +NOTE – Bandwidth allocation will be identified in the MAP using the transmitter ID (SID), receiver ID (DID) and channel estimation only indication set in the TXOP attributes extension (see clause 8.8.4.1.1). + +##### 8.11.1.7.8 Format of MCE\_ProbeSlotRelease.cnf + +The format of the MMPL of the MCE\_ProbeSlotRelease.cnf message shall be as shown in Table 8-16. + +**Table 8-16 – Format of the MMPL of the MCE\_ProbeSlotRelease.cnf message** + +| Field | Octet | Bits | Description | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|-------|-------------------------------------------------------------------------------------------------------------------| +| Transmitter ID | 0 | [7:0] | The DEVICE_ID of the node requesting the bandwidth allocation for PROBE frame transmissions. | +| Receiver ID | 1 | [7:0] | The DEVICE_ID of the receiver node in the channel estimation procedure. | +| CE_BMAT_ID | 2 | [4:0] | This field indicates the BMAT_ID associated with the runtime BMAT for which the bandwidth has to be released. | +| Request Status | | [7:5] | 0 – Request is confirmed
1 – Request is rejected (unknown BMAT identity) (Note)
2 to 7 – Reserved by ITU-T. | +| NOTE – There is no bandwidth allocated for the identified channel estimation procedure. The identification is defined by the Transmitter_ID, Receiver_ID, CE_BMAT_ID. | | | | + +##### 8.11.1.7.9 Format of MCE\_ParamUpdate.cnf + +The format of the MMPL of the MCE\_ParamUpdate.cnf message shall be as shown in Table 8-17. + +**Table 8-17 – Format of the MMPL of the MCE\_ParamUpdate.cnf message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| New BMAT ID | 0 | [4:0] | This field indicates the BMAT_ID specified in the received MCE_ParamUpdate.req message. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| NUM_AVAIL_BMATS_NO_PREC | 1 | [3:0] | This field contains the number of available runtime BMATs, assuming $G = 1$ and no precoding, that this node (SID) can support when transmitting to the destination node (DID). It excludes the BMAT associated with the CE_BMAT_ID. Valid values are from 0 to 12. | +| NUM_AVAIL_BMATS_PREC | | [7:4] | This field contains the number of available runtime BMATs, assuming $G = 1$ and $PG = 1$ (with the precoding parameters quantized to 8 bits), that this node (SID) can support when transmitting to the destination node (DID). It excludes the BMAT associated with the New BMAT ID. Valid values are from 0 to 12. | +| Request Status | 2 | [2:0] | 0 – BMAT successfully updated
1 – Update is rejected (no more resources)
2 – Update is rejected (New BMAT ID already exists)
3 to 7 – Reserved by ITU-T. | +| Reserved | | [7:3] | Reserved by ITU-T (Note). | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### 8.11.1.7.10 Format of MCE\_PartialBmatUpdate.cnf + +The format of the MMPL of the MCE\_PartialBmatUpdate.cnf message shall be as shown in Table 8-18. + +**Table 8-18 – Format of the MMPL of the MCE\_PartialBmatUpdate.cnf message** + +| Field | Octet | Bits | Description | +|-------------------------|-------|-------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_BMAT_ID | 0 | [4:0] | This field indicates the CE_BMAT_ID specified in the MCE_PartialBmatUpdate.req message. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| NUM_AVAIL_BMATs_NO_PREC | 1 | [3:0] | This field contains the number of available runtime BMATs, assuming $G = 1$ and no precoding, that this node (SID) can support when transmitting to the destination node (DID). It excludes the BMAT associated with the CE_BMAT_ID. Valid values are from 0 to 12. | +| NUM_AVAIL_BMATs_PREC | | [7:4] | This field contains the number of available runtime BMATs, assuming $G = 1$ and $PG = 1$ (with the precoding parameters quantized to 8 bits), that this node (SID) can support when transmitting to the destination node (DID). It excludes the BMAT associated with the CE_BMAT_ID. Valid values are from 0 to 12. | +| Request Status | 2 | [2:0] | 0 – BMAT successfully updated
1 – Request rejected (no more resources)
2 – Request rejected (O_BMAT_ID does not exist)
3 – Request rejected (N_BMAT_ID already exist)
4 to 7 – Reserved by ITU-T. | +| Reserved | | [7:3] | Reserved by ITU-T (Note). | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +##### 8.11.1.7.11 Format of MCE\_Request.ind + +The format of the MMPL of the MCE\_Request.ind message shall be as shown in Table 8-19. + +**Table 8-19 – Format of the MMPL of the MCE\_Request.ind message** + +| Field | Octet | Bits | Description | +|---------------|-------|-------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_WINDOW_SEL | 0 | [0] | This field shall be set to one if the transmitter selects the channel estimation window. It shall be set to zero, otherwise. If this field is set to zero, then CE_STIME and CE_ETIME shall be set to 00 16 and these values shall be ignored by the receiver. | +| Reserved | | [7:1] | Reserved by ITU-T (Note). | +| CE_STIME | 1 | [7:0] | This field indicates time at which the transmitter can start PROBE frame transmissions and it shall be coded as shown in Table 8-98 of [ITU-T G.9961]. | +| CE_ETIME | 2 | [7:0] | This field indicates time at which the transmitter shall end PROBE frame transmissions and it shall be coded as shown in Table 8-99 of [ITU-T G.9961]. | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +##### 8.11.1.7.12 Format of MCE\_Initiation.req + +The format of the MMPL of the MCE\_Initiation.req message shall be as shown in Table 8-20. + +**Table 8-20 – Format of the MMPL of the MCE\_Initiation.req message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|---------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_BMAT_ID | 0 and 1 | [4:0] | This field indicates the BMAT_ID associated with the runtime BMAT to be created by channel estimation. It shall be formatted as shown in Table 7-3. | +| CE_BAT_GRP | | [7:5] | This field indicates the value of BAT sub-carrier grouping. It shall be formatted as shown in Table 8-7. | +| CE_PR_GRP | | [10:8] | This field indicates the value of precoding sub-carrier grouping. It shall be formatted as shown in Table 8-8. | +| Reserved | | [15:11] | Reserved by ITU-T (Note). | +| CE_STIME | 2 | [7:0] | This field indicates time at which the transmitter can start PROBE frame transmissions and it shall be coded as shown in Table 8-98 of [ITU-T G.9961]. | +| CE_ETIME | 3 | [7:0] | This field indicates time at which the transmitter shall end PROBE frame transmissions and it shall be coded as shown in Table 8-99 of [ITU-T G.9961]. | +| CE_PRB_RQST | 4 | [0] | This field shall be set to one if the receiver wants PROBE frames along with channel estimation initiation confirmation. It shall be set to zero otherwise. | +| Reserved | | [7:1] | Reserved by ITU-T (Note). | +| CE_PRB_PARM | 5 to 9 | [39:0] | This field specifies a set of parameters for PROBE frame. It shall be coded as shown in Table 8-23. This field shall be set to 000000 16 if CE_PRB_RQST is set to zero. | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### 8.11.1.7.13 Format of MCE\_Initiation.cnf + +The format of the MMPL of the MCE\_Initiation.cnf message is shown in Table 8-21. + +**Table 8-21 – Format of the MMPL of the MCE\_Initiation.cnf message** + +| Field | Octet | Bits | Description | +|-----------------------------|---------|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_BMAT_ID | 0 and 1 | [4:0] | This field indicates the BMAT_ID associated with the runtime BAT to be created by channel estimation. It shall be formatted as shown in Table 7-3. | +| CE_BAT_GRP | | [7:5] | This field indicates the value of BAT sub-carrier grouping. It shall be formatted as shown in Table 8-7. | +| CE_PR_GRP | | [10:8] | This field indicates the value of precoding sub-carrier grouping. It shall be formatted as shown in Table 8-8. | +| Reserved | | [15:11] | Reserved by ITU-T (Note). | +| NUM_AVAIL_B
MATS_NO_PREC | 2 | [3:0] | This field contains the number of available runtime BMATs, assuming $G = 1$ and no precoding, that this node (SID) can support when transmitting to the destination node (DID). It excludes the BMAT associated with the CE_BMAT_ID. Valid values are from 0 to 12. | + +**Table 8-21 – Format of the MMPL of the MCE\_Initiation.cnf message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| NUM_AVAIL_B
MATS_PREC | | [7:4] | This field contains the number of available runtime BMATs, assuming $G = 1$ and $PG = 1$ (with the precoding parameters quantized to 8 bits), that this node (SID) can support when transmitting to the destination node (DID). It excludes the BMAT associated with the CE_BMAT_ID. Valid values are from 0 to 12. | +| Request Status | 3 | [2:0] | 0 – Channel estimation initiation is confirmed
1 – Rejected (CE_BMAT_ID is valid and currently in use)
2 – Rejected (Bandwidth for PROBE frame transmission is not available)
3 – Rejected (Bandwidth request for probe frame transmission is pending)
4 – Rejected (Channel estimation window is currently not available)
5 to 7 – Reserved by ITU-T (Note). | +| Reserved | | [7:3] | Reserved by ITU-T (Note). | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### 8.11.1.7.14 Format of MCE\_ProbeRequest.ind + +The format of the MMPL of the MCE\_ProbeRequest.ind message shall be as shown in Table 8-22. + +**Table 8-22 – Format of the MMPL of the MCE\_ProbeRequest.ind message** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|--------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_BMAT_ID | 0 | [4:0] | This field indicates the BMAT_ID associated with the runtime BMAT to be created by channel estimation. It shall be formatted as shown in Table 7-3. | +| CE_PRB_DEFAULT
_IND | | [5] | When this field is set to one, the parameters provided in this message (CE_PRB_PARM) replace the existing parameters for the default PROBE frame for this node (SID) when receiving from the destination node (DID). | +| Reserved | | [7:6] | Reserved by ITU-T (Note). | +| CE_PRB_PARM | 1 to 5 | [39:0] | See Table 8-23. | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +**Table 8-23 – Format of the CE\_PRB\_PARM field** + +| Field | Octet | Bits | Description | +|----------------------|-------|-------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_PR_PRBTTYPE | 0 | [3:0] | This field indicates the PRBTTYPE requested by the receiver. It shall be formatted as shown in Table 7-8. | +| CE_PR_PRBFN | | [7:4] | This field indicates the number of PROBE frames that shall be sent by the transmitter at each request for PROBE frame transmission. The field shall be coded as shown in Table 8-103 of [ITU-T G.9961]. The transmitter may send multiple PROBE frames within a single channel estimation window. | +| CE_PR_PRBSYM | 1 | [3:0] | This field indicates the PRBSYM requested by the receiver. It shall be formatted as shown in Table 7-41 of [ITU-T G.9960]. | +| CE_PR_PRBGI | | [6:4] | This field indicates the PRBGI requested by the receiver. It shall be formatted as shown in Table 7-14 of [ITU-T G.9960]. | +| Reserved | | [7] | Reserved by ITU-T (Note 1). | +| CE_PR_APSD_MAX | 2 | [4:0] | This field indicates the APSD_MAX-P requested by the receiver. It shall be formatted as described in clause 7.1.2.3.2.7.4. (Note 3) | +| CE_PR_APSD_MAX_EXT | | [5] | This field indicates the APSD_MAX_EXT-P requested by the receiver. It shall be formatted as described in clause 7.1.2.3.2.7.1.7 of [ITU-T G.9960]. (Note 3) | +| Reserved | | [7:6] | Reserved by ITU-T (Note 1). | +| PRB_BMAT_ID | 3 | [4:0] | This field indicates the BMAT_ID (predefined or runtime) whose MAT shall be used by the transmitter of the PROBE frame in the Tx port mapper in case a 2 SS channel estimation PROBE frame is requested in the CE_PR_PRBTTYPE field.
The BMAT_ID indicated in this field shall be a valid BMAT_ID.
If this field conveys a predefined BMAT_ID, the valid values for channel estimation shall be 3, 7 and 11.
This field is only valid if 2 SS channel estimation PROBE is requested in the CE_PR_PRBTTYPE field (PRBTTYPE = 1000 2 ). Otherwise, this field shall be set to 0 and ignored by the receiver. | +| Reserved | | [7:5] | Reserved by ITU-T (Note). | +| CE_PR_NUM_SILENT_SYM | 4 | [5:0] | This field indicates the number of silent symbols requested by the receiver. It shall be formatted as described in clause 7.1.2.3.2.7.2.3.3.
This field is only valid if 2 SS channel estimation PROBE is requested in the CE_PR_PRBTTYPE field (PRBTTYPE = 1000 2 ). Otherwise, this field shall be set to 0 and ignored by the receiver (Note 2). | + +**Table 8-23 – Format of the CE\_PRB\_PARM field** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|-------|-----------------------------| +| Reserved | | [7:6] | Reserved by ITU-T (Note 1). | +| NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | +| NOTE 2 – First (CE_PR_PRBSYM – CE_PR_NUM_SILENT_SYM) symbols of the 2 SS channel estimation PROBE frame are normal (non-silent) probe symbols. | | | | +| NOTE 3 – It is the responsibility of the receiver to set CE_PR_APSD_MAX and CE_PR_APSD_MAX_EXT taking into account the PSD limitations and capabilities of the transmitter that are known to the receiver (see clause 7.1.5). | | | | + +##### 8.11.1.7.15 Format of MCE\_Cancellation.req + +The format of the MMPL of the MCE\_Cancellation.req message shall be as shown in Table 8-24. + +**Table 8-24 – Format of the MMPL of the MCE\_Cancellation.req message** + +| Field | Octet | Bits | Description | +|----------------|-------|-------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_BMAT_ID | 0 | [4:0] | This field indicates the channel estimation identifier that is cancelled. It shall be formatted as shown in Table 7-3. | +| USE_RCM | | [5] | When set to one it means the transmitter may use RCM with parameters communicated in the New block size, New FEC rate, Bandplan ID and Repetitions fields. It shall be set to zero otherwise. | +| Reserved | | [7:6] | Reserved by ITU-T (Note). | +| New block size | 1 | [1:0] | When USE_RCM is set to one this field indicates the proposed BLKSZ associated to RCM. It shall be formatted as shown in Table 7-7 of [ITU-T G.9960]. It shall be set to 00 2 otherwise. | +| New FEC rate | | [4:2] | When USE_RCM is set to one this field indicates the proposed FEC_RATE associated to RCM. It shall be formatted as shown in Table 7-12 of [ITU-T G.9960]. It shall be set to 000 2 otherwise. | +| OFB ID | | [7:5] | When USE_RCM is set to one this field indicates the OFB based on which the RCM parameters are proposed. It shall be formatted as shown in Table 7-11 of [ITU-T G.9960]. It shall be set to 000 2 otherwise. | +| Repetitions | 2 | [2:0] | When USE_RCM is set to one this field indicates the proposed number of repetitions associated with RCM. It shall be formatted as shown in Table 7-9 of [ITU-T G.9960]. It shall be set to 000 2 otherwise. | +| RCM_BAT_ID | | [3] | When USE_RCM is set to one, this field indicates the predefined BAT associated with RCM. It shall be set to the following value:
zero, when predefined BAT Type 1 is used
one, when predefined BAT Type 2 is used. | +| Reserved | | [7:4] | Reserved by ITU-T (Note). | + +**Table 8-24 – Format of the MMPL of the MCE\_Cancellation.req message** + +| Field | Octet | Bits | Description | +|-----------|-------|-------|-------------------------------------------------------------------------------------------------------------------------------------------------| +| RCM_GI_ID | 3 | [2:0] | When USE_RCM is set to one, this field indicates the GI_ID associated with RCM. It shall be formatted as shown in Table 7-14 of [ITU-T G.9960]. | +| Reserved | | [7:3] | Reserved by ITU-T (Note). | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +##### 8.11.1.7.16 Format of MCE\_BmatIdMaintain.ind + +The format of the MMPL of the MCE\_BmatIdMaintain.ind message shall be as shown in Table 8-25. + +**Table 8-25 – Format of the MMPL of the MCE\_BmatIdMaintain.ind message** + +| Field | Octet | Bits | Description | +|----------------------------|---------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| VALID_BMAT_ID | 0 and 1 | [15:0] | This field contains a bitmap indicating which runtime BMATs are valid for this node (SID) when receiving from the destination node (DID). Each bit is associated with one runtime BMAT. Bit 0 of the VALID_BMAT_ID shall be set if runtime BMAT_ID 16 is valid. Bit 11 of the VALID_BMAT_ID shall be set if runtime BMAT_ID 27 is valid. | +| NUM_TX_AVAIL_BMATS_NO_PREC | 2 | [3:0] | This field contains the number of available runtime BMATs, assuming $G = 1$ and no precoding, that this node (SID) can support when transmitting to the destination node (DID). Valid values are from 0 to 12. | +| NUM_TX_AVAIL_BMATS_PREC | | [7:4] | This field contains the number of available runtime BMATs, assuming $G = 1$ and $PG = 1$ (with the precoding parameters quantized to 8 bits), that this node (SID) can support when transmitting to the destination node (DID). Valid values are from 0 to 12. | +| New block size | 3 | [1:0] | This field indicates the proposed BLKSZ associated with RCM, if there is no available runtime BAT (Note 2). It shall be formatted as shown in Table 7-7 of [ITU-T G.9960]. It shall be set to 0 otherwise. | +| New FEC rate | | [4:2] | This field indicates the proposed FEC_RATE associated with RCM, if there is no available runtime BAT (Note 2). It shall be formatted as shown in Table 7-12 of [ITU-T G.9960]. It shall be set to 0 otherwise. | +| OFB ID | | [7:5] | This field indicates the OFB based on which the RCM parameters are proposed, if there is no available runtime BAT (Note 2). It shall be formatted as shown in Table 7-11 of [ITU-T G.9960]. It shall be set to 0 otherwise. | +| Repetitions | 4 | [2:0] | This field indicates the proposed number of repetitions associated with RCM, if there is no available runtime BAT (Note 2). It shall be formatted as shown in Table 7-9 of [ITU-T G.9960]. It shall be set to 0 otherwise. | + +**Table 8-25 – Format of the MMPL of the MCE\_BmatIdMaintain.ind message** + +| Field | Octet | Bits | Description | +|------------|-------|-------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| RCM_BAT_ID | | [3] | This field indicates the predefined BAT associated with RCM, if there is no available runtime BAT (Note 2). It shall be set to the following value:
zero, when predefined BAT Type 1 is used
one, when predefined BAT Type 2 is used. | +| Reserved | | [7:4] | Reserved by ITU-T (Note 1). | +| RCM_GI_ID | 5 | [2:0] | This field indicates the GI_ID associated with RCM, if there is no available runtime BAT (Note 2). It shall be formatted as shown in Table 7-14 of [ITU-T G.9960]. | +| Reserved | | [7:3] | Reserved by ITU-T (Note 1). | + +NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. +NOTE 2 – Runtime BATs might only be available for specified time periods (see Table 8-93). + +##### 8.11.1.7.17 Format of MCE\_Cancellation.cnf + +The format of the MMPL of the MCE\_Cancellation.cnf message shall be as shown in Table 8-26. + +**Table 8-26 – Format of the MMPL of the MCE\_Cancellation.cnf message** + +| Field | Octet | Bits | Description | +|----------------|-------|-------|---------------------------------------------------------------------------------------------------------------------------------------------------| +| CE_BMAT_ID | 0 | [4:0] | This field indicates the BMAT_ID specified in the received MCE_Cancellation.req message. | +| Request Status | | [7:5] | 0 – Channel estimation is successfully cancelled.
1 – No ongoing channel estimation for this CE_BMAT_ID.
2 to 7 – Reserved by ITU-T (Note). | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +## 8.12 Connection management + +See clause 8.12 of [ITU-T G.9961]. + +## 8.13 Message flooding + +See clause 8.13 of [ITU-T G.9961]. + +## 8.14 Operation in the presence of neighbouring domains – Distributed domain coordination (NDIM) + +See clause 8.14 of [ITU-T G.9961]. + +## 8.15 Coexistence with alien power-line networks + +See clause 8.15 of [ITU-T G.9961]. + +## 8.16 PHY multicast binding protocol + +PHY multicast binding is specified for the case of a single SS. The transmitter may use either of the following two transmission schemes when transmitting to the PHY multicast group (see Note in Table 7-1): + +- ITU-T G.9960 transmission +- MIMO transmission with the payload created as a single SS + +Transmissions to a PHY multicast group using two spatial streams (i.e., MIMO modes 0, 1 and 2) are for further study. + +See clause 8.16 of [ITU-T G.9961]. + +## **8.17 DLL multicast stream** + +See clause 8.17 of [ITU-T G.9961]. + +## **8.18 Inter-OFB interoperability** + +See clause 8.18 of [ITU-T G.9961]. + +## **8.19 Node information and capabilities exchange** + +See clause 8.19 of [ITU-T G.9961]. + +## **8.20 Metrics acquisition** + +See clause 8.20 of [ITU-T G.9961] + +## **8.21 Operation in power saving modes** + +See clause 8.21 of [ITU-T G.9961] + +## **8.22 Layer 2 configuration and management protocol (LCMP)** + +See clause 8.22 of [ITU-T G.9961] + +## **8.23 MIMO transmission** + +As stated in previous clauses, a MIMO transceiver shall be capable of transmitting using the following two transmission schemes: + +- ITU-T G.9960 transmission based on the reference models and PHY frame format defined in [ITU-T G.9960]. +- MIMO transmission based on the reference models and PHY frame format defined in ITU-T G.9963. + +The following subclauses deal with MIMO transmission only and describe the different operation modes in the two cases of MIMO transmission: the case where the payload is created as a single spatial stream (SS), and the case in which the payload is created as two SSs. + +### **8.23.1 MIMO transmission, payload created as one spatial stream** + +MIMO transmission with the payload created as a single SS (cases 4b, 5, 6, 7 in Table 7-1) can be done either by using predefined BATs or using runtime BATs. These transmissions are done using the MIMO transmission scheme with a single spatial stream as described in clause 7.1.2.1 and using *TPM#1* as defined in clause 7.1.4.4.1.2. + +### **8.23.2 MIMO transmission, payload created as two spatial streams** + +MIMO transmission with the payload created as two SSs can be done in one of two ways: either using predefined BMATs (which use a predefined BAT and a predefined Tx port mapping), or using runtime BMATs, as described in clause 7.1.2.3.2.2.8. + +The various options of MIMO transmission with the payload created as two SSs using predefined BMATs are specified in Table 7-3 of clause 7.1.2.3.2.2.8. This includes: + +- Single port transmissions, with *TPM#3* (for transmissions through Tx port 1) or *TPM#4* (for transmissions through Tx port 2), BMAT\_IDs 0 to 7. +- Transmissions over the two Tx ports, with *TPM#0*, BMAT\_IDs 8 to 11. + +MIMO transmission with the payload created as two SSs using runtime BMATs, is done using one of three modes of operation specified hereafter. These modes of operation specify the transmission parameters used to generate the transmitted signal. These modes refer to the entire set of sub-carriers and not a specific sub-carrier. Two of the specified modes require feedback from the receiver to the transmitter, hence are referred to as "closed loop" modes, while one mode does not require such a feedback, hence is referred to as an "open loop" mode. + +The following modes of operation are defined: + +- 1) Mode 0: + - Open loop + - Tx port mapping: In this case no precoding is applied. For sub-carriers with bits from either the encoded payload block or the LFSR loaded on two SSs, + - if both BATs use values in the range 0 to 12 for both spatial streams, *TPM#0* is used; or + - if the BAT for SS 1 uses the special value 15, *TPM #4* is used; or + - if the BAT for SS 2 uses the special value 15, *TPM #3* is used. +- 2) Mode 1: + - Closed loop + - Tx port mapping: For sub-carriers with bits from either the encoded payload block or the LFSR loaded on two SSs, + - if both BATs use values in the range 0 to 12 for both spatial streams, *TPM#5* is used; or + - if the BAT for SS 1 uses the special value 15, *TPM #7* is used; or + - if the BAT for SS 2 uses the special value 15, *TPM #6* is used. +- 3) Mode 2: + - Closed loop + - Tx port mapping: For sub-carriers with bits from either the encoded payload block or the LFSR loaded on two SSs, + - if both BATs use values in the range 0 to 12 for both spatial streams, *TPM#5* is used; or + - if the BAT for SS 1 uses the special value 15, *TPM #4* is used; or + - if the BAT for SS 2 uses the special value 15, *TPM #3* is used. + +The mode of operation, which is associated with a specific BMAT\_ID, is indicated by the "MIMO mode indicator" field in the MCE\_ParamUpdate.req message (see Table 8-6). + +The BATs for all of these modes are used to code the Tx port information for each sub-carrier, described above, for the three operational modes, in the way described in the following table: + +**Table 8-27 – Tx port mapping matrix for a specific sub-carrier** + +| Coding of the bit loading in the BAT | | MIMO mode | | | +|--------------------------------------|---------------------|-----------|--------|--------| +| Spatial stream 1 | Spatial stream 2 | Mode 0 | Mode 1 | Mode 2 | +| $0 \leq x1 \leq 12$ | $0 \leq x2 \leq 12$ | TPM #0 | TPM #5 | TPM #5 | +| 15 | $0 \leq x2 \leq 12$ | TPM #4 | TPM #7 | TPM #4 | +| $0 \leq x1 \leq 12$ | 15 | TPM #3 | TPM #6 | TPM #3 | + +NOTE – Combinations of $x1$ and $x2$ not listed in the table are not valid. + +The receiver determines the mode of operation. This mode is associated with a specific BMAT\_ID. + +When operating in Mode 0, the receiver sends to the transmitter an MCE\_ParamUpdate.req or MCE\_PartialBmatUpdate.req message (as part of the channel estimation procedure, see clause 8.11.1), which includes, the following parameters: + +- The "MIMO mode indicator" (included only in the MCE\_ParamUpdate.req message). +- BATs for the two SSs. +- BAT grouping ( $G$ ). + +When operating in Mode 1 or Mode 2, the receiver sends to the transmitter an MCE\_ParamUpdate.req or MCE\_PartialBmatUpdate.req message, which includes the following parameters in addition to the parameters mentioned previously for Mode 0: + +- Precoding angles. +- Precoding grouping ( $PG$ ). + +## **8.24 Run-length compression of fields of management messages** + +See clause 8.23 of [ITU-T G.9961]. + +## **8.25 Payload compression in management messages** + +See clause 8.24 of [ITU-T G.9961]. + +## **8.26 TLV pool** + +See clause 8.25 of [ITU-T G.9961]. + +# **9 Security** + +See clause 9 of [ITU-T G.9961]. + +# **Annex A** + +## **Regional requirements for North America** + +(This annex forms an integral part of this Recommendation.) + +See Annex A of [ITU-T G.9960]. + +# **Annex B** + +(This annex forms an integral part of this Recommendation.) + +See Annex B of [ITU-T G.9960]. + +NOTE – Annex B of [ITU-T G.9960] was intentionally left blank. + +# **Annex C** + +## **Regional requirements for Japan** + +(This annex forms an integral part of this Recommendation.) + +See Annex C of [ITU-T G.9960]. + +# **Annex D** + +## **International amateur radio bands** + +(This annex forms an integral part of this Recommendation.) + +See Annex D of [ITU-T G.9964]. + +# **Annex E** + +## **Impact of ITU-T G.9960 on VDSL2 service** + +(This annex forms an integral part of this Recommendation.) + +See Annex E of [ITU-T G.9964]. + +# **Annex F** + +(This annex has been intentionally left blank.) + +# **Annex G** + +## **Test vectors** + +(This annex forms an integral part of this Recommendation.) + +See Annex G of [ITU-T G.9960]. + +NOTE – Test vectors for OFB Profile 2 is for further study. + +# **Annex H** + +## **Application protocol convergence sublayer** + +(This annex forms an integral part of this Recommendation.) + +See Annex A of [ITU-T G.9961]. + +# **Annex I** + +## **Interoperability between Profile 1 and Profile 2 OFB transmissions** + +(This annex forms an integral part of this Recommendation.) + +See Annex J of [ITU-T G.9960]. + +# **Annex J** + +## **IEEE 802.1X port-based network access control** + +(This annex forms an integral part of this Recommendation.) + +See Annex D of [ITU-T G.9961]. + +# **Annex K to Annex Q** + +Annexes K to Q have been intentionally left blank. + +# **Annex R** + +## **Use of reverse power feeding techniques for G.hn over coaxial media** + +(This annex forms an integral part of this Recommendation.) + +See Annex R of [ITU-T G.9961]. + +# **Annex S to Annex W** + +Annexes S to W have been intentionally left blank. + +# **Annex X** + +## **Test vectors** + +(This annex forms an integral part of this Recommendation.) + +See Annex X of [ITU-T G.9961]. + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.997.2-201903-I_PDF-E/raw.md b/marked/G/T-REC-G.997.2-201903-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..3b514d609161fb3493b762998f3c34ae05eb3d50 --- /dev/null +++ b/marked/G/T-REC-G.997.2-201903-I_PDF-E/raw.md @@ -0,0 +1,6085 @@ + + +International Telecommunication Union + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.997.2** + +(03/2019) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Metallic access +networks + +--- + +**Physical layer management for G.fast +transceivers** + +Recommendation ITU-T G.997.2 + +ITU-T + +![ITU logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg) + +The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking across it. To the right of the globe, the text "International Telecommunication Union" is written in a blue, sans-serif font. + +ITU logo + +International +Telecommunication +Union + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.997.2 + +# Physical layer management for G.fast transceivers + +## Summary + +Recommendation ITU-T G.997.2 specifies the physical layer management for fast access to subscriber terminals (G.fast) transmission systems. It specifies managed objects for configuration, fault, status, inventory and performance management. + +The 2018 edition of this Recommendation integrates ITU-T G.997.2 (2015) and all its amendments and corrigenda. It adds the following new technical material: + +- correction on loss of power definition for reverse power feeding (RPF); +- correction to the special value of SNRps; +- inclusion of managed objects for showtime reconfiguration; +- correction to the range of valid values of LOM\_PERSISTENCYds/us; +- inclusion of managed objects CLASSMASKds/us. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.997.2 | 2015-05-22 | 15 | 11.1002/1000/12375 | +| 1.1 | ITU-T G.997.2 (2015) Cor. 1 | 2016-03-29 | 15 | 11.1002/1000/12800 | +| 1.2 | ITU-T G.997.2 (2015) Amd. 1 | 2016-05-07 | 15 | 11.1002/1000/12555 | +| 1.3 | ITU-T G.997.2 (2015) Amd. 2 | 2016-07-22 | 15 | 11.1002/1000/12799 | +| 1.4 | ITU-T G.997.2 (2015) Cor. 2 | 2016-12-22 | 15 | 11.1002/1000/13067 | +| 1.5 | ITU-T G.997.2 (2015) Amd. 3 | 2017-04-06 | 15 | 11.1002/1000/13066 | +| 1.6 | ITU-T G.997.2 (2015) Cor. 3 | 2017-08-13 | 15 | 11.1002/1000/13311 | +| 1.7 | ITU-T G.997.2 (2015) Amd. 4 | 2017-12-07 | 15 | 11.1002/1000/13310 | +| 1.8 | ITU-T G.997.2 (2015) Cor. 4 | 2018-03-16 | 15 | 11.1002/1000/13535 | +| 1.9 | ITU-T G.997.2 (2015) Amd. 5 | 2018-08-06 | 15 | 11.1002/1000/13534 | +| 2.0 | ITU-T G.997.2 | 2019-03-22 | 15 | 11.1002/1000/13752 | + +## Keywords + +Distribution point unit, DPU, G.fast transceivers, management, performance monitoring. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|------|--------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 1 | +| 3.1 | Terms defined elsewhere ..... | 1 | +| 3.2 | Terms defined in this Recommendation..... | 1 | +| 4 | Abbreviations and acronyms ..... | 2 | +| 5 | Management architecture..... | 4 | +| 6 | Network management protocol..... | 6 | +| 7 | Managed objects ..... | 6 | +| 7.1 | Line configuration objects ..... | 20 | +| 7.2 | Channel configuration objects ..... | 39 | +| 7.3 | Data path configuration objects ..... | 43 | +| 7.4 | Line failures ..... | 43 | +| 7.5 | Channel failures ..... | 44 | +| 7.6 | Data path failures ..... | 45 | +| 7.7 | Line performance monitoring objects ..... | 45 | +| 7.8 | Channel performance monitoring objects ..... | 50 | +| 7.9 | Data path performance monitoring objects ..... | 52 | +| 7.10 | Line test, diagnostics and status objects ..... | 53 | +| 7.11 | Channel test, diagnostics and status objects ..... | 67 | +| 7.12 | Data path test, diagnostics and status objects ..... | 72 | +| 7.13 | Inventory objects ..... | 72 | +| 7.14 | Link State related managed objects ..... | 75 | +| 8 | Procedures for performance monitoring functions ..... | 76 | +| 8.1 | Line transmission states ..... | 76 | +| 8.2 | Threshold reports ..... | 77 | +| 8.3 | Unavailable and available state filters ..... | 78 | +| 8.4 | TR1 filter ..... | 78 | +| 8.5 | TR2 filter ..... | 78 | +| 8.6 | Evaluation of TR1 ..... | 78 | +| 8.7 | Evaluation of TR2 ..... | 78 | +| 8.8 | Threshold report evaluation during transmission state changes..... | 79 | +| 8.9 | Performance history storage in network elements..... | 79 | +| 8.10 | Register size..... | 79 | +| 8.11 | Parameter counts ..... | 79 | +| 8.12 | Date/time-stamping of reports ..... | 80 | +| 8.13 | Inhibiting performance monitoring parameters ..... | 80 | + +| | | +|----------------------------------------------------------------------------------------------|-----| +| Annex A Physical layer management for reverse power feeding of remote access equipment ..... | 81 | +| A.1 Scope ..... | 81 | +| A.2 References ..... | 81 | +| A.3 Definitions ..... | 81 | +| A.4 Abbreviations and acronyms ..... | 82 | +| A.5 DPU and NT management architecture ..... | 82 | +| A.6 Network management protocol ..... | 83 | +| A.7 DPU Northbound managed objects ..... | 87 | +| Annex B to Annex R ..... | 98 | +| Annex S Management for network termination software upgrade process ..... | 99 | +| S.1 Scope ..... | 99 | +| S.2 References ..... | 99 | +| S.3 Definitions ..... | 99 | +| S.4 Abbreviations and acronyms ..... | 99 | +| S.5 DPU management architecture ..... | 99 | +| S.6 Network management protocol ..... | 99 | +| S.7 Managed objects ..... | 99 | +| Annex T Annex X, Annex D and Annex T of ITU-T G.9701 – Managed objects ..... | 104 | +| T.1 Overview of Annex X, Annex D and Annex T of ITU-T G.9701 managed objects ..... | 104 | +| T.2 Annex X, Annex D and Annex T of [ITU-T G.9701] configuration objects ..... | 105 | +| T.3 Annex X, Annex D and Annex T of ITU-T G.9701 status objects ..... | 108 | +| T.4 Annex X, Annex D and Annex T of ITU-T G.9701 inventory objects ..... | 109 | +| Annex U to Annex W ..... | 110 | +| Annex X Cross-layer link state objects ..... | 111 | +| X.1 Overview of cross-layer link state objects ..... | 111 | +| X.2 Cross-layer low power mode control ..... | 111 | +| Appendix I Broadband Forum considerations on the FTTdp deployment scenario ..... | 116 | +| Bibliography ..... | 117 | + +## Recommendation ITU-T G.997.2 + +# Physical layer management for G.fast transceivers + +# 1 Scope + +This Recommendation specifies the physical layer management for fast access to subscriber terminals (G.fast) transmission systems. + +It specifies managed objects for configuration, fault, status, inventory and performance management. The list of managed objects applies at the distribution point unit-Northbound (DPU-NB) interface, relating to the "DPU-MIB" nomenclature used in [ITU-T G.9701]. The managed objects are defined to provide, at least, all the information necessary for translation into a YANG data model [b-IETF RFC 6020], although this does not exclude translation to other formats such as an abstract syntax notation one (ASN.1) (ITU-T X.680 series) management information base (MIB) description used in connection with the simple network management protocol (SNMP) [b-IETF RFC 1157]. The definition of the YANG data model for G.fast-managed objects is outside the scope of this Recommendation. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.994.1] Recommendation ITU-T G.994.1 (2018), *Handshake procedures for digital subscriber line transceivers*. +- [ITU-T G.9700] Recommendation ITU-T G.9700 (2014), *Fast access to subscriber terminals (G.fast) – Power spectral density specification*. +- [ITU-T G.9701] Recommendation ITU-T G.9701 (2019), *Fast access to subscriber terminals (G.fast) – Physical layer specification*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following term defined elsewhere: + +- 3.1.1 managed resource** [b-ITU-T M.3010]: The abstraction of those aspects of a telecommunication resource (logical or physical) required for telecommunications management. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +- 3.2.1 AdminStatus** (Based on clause 12.1.1.7 of [ITU-T G.9701]): The AdminStatus represents the configured, desired state of the interface. The AdminStatus "up" is equivalent with the interface "enabled=true", where the desired link state is L0, L2.1N, L2.1B, or L2.2. The AdminStatus "down" is equivalent with the interface "enabled=false", where the desired link state is L3. + +NOTE – The relation between the AdminStatus ("up" or "down") and the interface (enabled="true" or "false") is defined in the IETF YANG Data Model for Interface Management [b-IETF RFC 7223]. + +**3.2.2 anomaly:** A discrepancy between the actual and desired characteristics of an item. + +The desired characteristic may be expressed in the form of a specification. + +An anomaly may or may not affect the ability of an item to perform a required function. + +**3.2.3 defect:** A limited interruption in the ability of an item to perform a required function. It may or may not lead to maintenance action depending on the results of additional analysis. + +Successive anomalies causing a decrease in the ability of an item to perform a required function are considered a defect. + +**3.2.4 empty array:** An array whose number of elements is zero. + +**3.2.5 failure:** A termination of the ability of an item to perform a required function. + +NOTE – After failure, the item has a fault. Analysis of successive anomalies or defects affecting the same item can lead to the item being considered as "failed". + +**3.2.6 managed object:** The management view of a managed resource. + +**3.2.7 DPU-NB interface:** The interface between the persistent management agent and the management entity of the distribution point unit. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------|-------------------------------------------------------------------------------------| +| AN | Access Node | +| ASN.1 | Abstract Syntax Notation one | +| cDTA | coordinated DTA | +| CE | Cyclic Extension | +| CRC | Cyclic Redundancy Check | +| CV | Code Violation | +| CV-C | Code Violation – Channel | +| DPU | Distribution Point Unit | +| DPU-NB | DPU Northbound | +| DRA | Dynamic Resource Allocation | +| DTA | Dynamic Time Assignment | +| eoc | embedded operations channel | +| ES | Errored Second | +| FAST | Fast Access to Subscriber Terminals | +| FE | Far-End | +| FRA | Fast Rate Adaptation | +| FTTdp | Fibre To The distribution point | +| FTTx | Fibre To The x | +| FTU | FAST Transceiver Unit | +| FTU-O | FAST Transceiver Unit – Central office end (i.e., network operator end of the loop) | +| FTU-R | FAST Transceiver Unit – Remote side (i.e., subscriber end of the loop) | +| GDR | Gamma Data Rate | + +| | | +|--------|----------------------------------------------------| +| G.fast | fast access to subscriber terminals | +| iDTA | independent DTA | +| LOM | Loss of Margin | +| LOM-FE | Far-End Loss of Margin | +| LOR | Loss of RMC | +| LOR-FE | Far-End Loss of RMC | +| LORS | LOR Second | +| LOS | Loss of Signal | +| LOS-FE | Far-End Loss of Signal | +| LOSS | LOS Second | +| LPR | Loss of Power | +| LPR-FE | Far-End Loss of Power | +| MIB | Management Information Base | +| MDU | Multi-Dwelling Unit | +| ME | Management Entity | +| NDR | Net Data Rate | +| NDRds | downstream Net Data Rate | +| NDRus | upstream Net Data Rate | +| NE | Network Element | +| NMS | Network Management System | +| NOI | Normal Operation Interval | +| NT | Network Termination | +| OLR | On-Line Reconfiguration | +| OSS | Operations Support Systems | +| PM | Performance Monitoring | +| PMA | Persistent Management Agent | +| PMD | Physical Media Dependent | +| PMS-TC | Physical Media Specific – Transmission Convergence | +| PSD | Power Spectral Density | +| REIN | Repetitive Electrical Impulse Noise | +| RMC | Robust Management Channel | +| RPF | Reverse Power Feeding | +| RPA | RMC Parameter Adjustment | +| SES | Severely Errored Second | +| SNMP | Simple Network Management Protocol | +| SNR | Signal-to-Noise Ratio | +| SRA | Seamless Rate Adaptation | + +| | | +|--------|-----------------------------------------------------------------| +| SREC | Showtime Reconfiguration | +| TDD | Time Division Multiplexing | +| TIGA | Transmitter-Initiated Gain Adjustment | +| TPS-TC | Transport Protocol Specific – Transmission Convergence | +| TR | Threshold Report | +| UAS | UnAvailable Second | +| U-O | Loop interface – Central office end | +| U-R | Loop interface – Remote side (i.e., subscriber end of the loop) | + +# 5 Management architecture + +The management of an access node (AN) or a distribution point unit (DPU) is performed by the network management system (NMS), passing management information over the Q reference point to each AN's management entity (ME) (see Figure 5-1a) or through a persistent management Agent (PMA) to the each DPU's ME (see Figure 5-1b). The NMS may also monitor each G.fast transceiver unit – remote side (FTU-R) via the related network termination's (NT's) ME and G reference point. The connection between the ME functions at the AN or DPU and at the NT is established over management channels provided by the G.fast transceiver unit – central office ends (FTU-Os) and FTU-Rs via the copper pairs. + +![Figure 5-1a: Reference model of traditional AN deployment. The diagram shows a network management system (NMS) connected to a Distribution Point Unit (DPU) and a Network Termination (NT-1) via a copper pair. The NMS is connected to the DPU's Management Entity (ME) via the Q reference point. The DPU contains a PHY, L2+, and FTU-O-1. The NT-1 contains a PHY, L2+, and FTU-R-1. The copper pair connects the FTU-O-1 to the FTU-R-1. The U-O (Loop interface – Central office end) is at the DPU side, and the U-R (Loop interface – Remote side) is at the NT-1 side. The G reference point is at the NT-1 side. The diagram also shows the HON (Home Office Network) and ODN (Optical Distribution Network) connected to the DPU. The reference points V, Q, G, and T/S are indicated by dashed lines.](e6df2733626a85205c1db682e6259c46_img.jpg) + +G.997.2(15)-Cor.1(16)\_F5-1a + +Figure 5-1a: Reference model of traditional AN deployment. The diagram shows a network management system (NMS) connected to a Distribution Point Unit (DPU) and a Network Termination (NT-1) via a copper pair. The NMS is connected to the DPU's Management Entity (ME) via the Q reference point. The DPU contains a PHY, L2+, and FTU-O-1. The NT-1 contains a PHY, L2+, and FTU-R-1. The copper pair connects the FTU-O-1 to the FTU-R-1. The U-O (Loop interface – Central office end) is at the DPU side, and the U-R (Loop interface – Remote side) is at the NT-1 side. The G reference point is at the NT-1 side. The diagram also shows the HON (Home Office Network) and ODN (Optical Distribution Network) connected to the DPU. The reference points V, Q, G, and T/S are indicated by dashed lines. + +**Figure 5-1a – Reference model of traditional AN deployment +(shown for line 1 in all N lines (N≥1) connected to an AN)** + +![Figure 5-1b: Reference model of FTTdp deployment with PMA and DPU. The diagram shows a network architecture where an NMS (Network Management System) is connected to a PMA (Power Management Assembly) via a Q interface. The PMA is connected to a DPU (Distribution Point Unit) via a DPU-NB interface. The DPU contains a ME (Management Entity), a PHY, an L2+ switch, and an FTU-O. The FTU-O is connected to a Copper-pair (U-O to U-R). The Copper-pair is connected to an NT-1 (Network Termination) which contains an FTU-R-1, an L2+ switch, and a PHY. The NT-1 is connected to a T/S (Terminal System) via a G interface. The diagram also shows a HON (Home Optical Network) connected to an ODN (Optical Distribution Network) which is connected to the DPU. The diagram is labeled G.997.2(15)-Cor.1(16)_F5-1b.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +Figure 5-1b: Reference model of FTTdp deployment with PMA and DPU. The diagram shows a network architecture where an NMS (Network Management System) is connected to a PMA (Power Management Assembly) via a Q interface. The PMA is connected to a DPU (Distribution Point Unit) via a DPU-NB interface. The DPU contains a ME (Management Entity), a PHY, an L2+ switch, and an FTU-O. The FTU-O is connected to a Copper-pair (U-O to U-R). The Copper-pair is connected to an NT-1 (Network Termination) which contains an FTU-R-1, an L2+ switch, and a PHY. The NT-1 is connected to a T/S (Terminal System) via a G interface. The diagram also shows a HON (Home Optical Network) connected to an ODN (Optical Distribution Network) which is connected to the DPU. The diagram is labeled G.997.2(15)-Cor.1(16)\_F5-1b. + +**Figure 5-1b – Reference model of FTTdp deployment with PMA and DPU +(shown for line 1 in all N lines (N≥1) connected to a DPU)** + +Appendix I contains additional information regarding the Broadband Forum considerations on the fibre to the distribution point (FTTdp) deployment scenario (see also [b-BBF TR-301]). + +The fundamental purpose of the PMA (see Appendix I) is to allow the operations support systems (OSS)/NMS to perform all operations on a given DPU whether or not that DPU is actually powered. This includes the following PMA functionality: + +- firmware download and management; +- initial provisioning; +- configuration, including rate control; +- test and diagnostics; +- statistics gathering; +- event reporting; +- performance monitoring (PM) history beyond current and previous interval counters; +- management protocol translation between Q interface and the DPU-Northbound interface (DPU-NB interface). + +Some of these operations have limited capabilities when the DPU is without power. For example, statistics gathering is limited to the history present in the PMA, since the current information is not available from the DPU. + +The OSS/NMS also still needs to be able to ascertain the true power state of the DPU as a whole, and of each given line, for example for diagnostics purposes. It can choose to take into account the power state of a DPU for various processes, e.g., a new firmware download, but does not have to. + +While distribution points are at locations where local power is typically not available, DPUs may also be deployed at locations where local powering or forward powering is available (e.g., in multi-dwelling unit (MDU) basements or in fibre to the x (FTTx) cabinets). In this case, a PMA could still exist as a separate entity to the DPU (if the DPU could still be unpowered at times). + +[ITU-T G.9701] defines the interfaces between the FTU-O (which is part of the AN or DPU) and the FTU-R (which is part of the NT). This Recommendation specifies the physical layer management for fast access to subscriber terminals (G.fast) transmission systems as seen by the NMS (if the FTU-O is in an AN, see Figure 5-1a) and as seen by the PMA (if the FTU-O is in a DPU, see Figure 5-1b). + +Clause 7 and 8 specifies managed objects for configuration, fault, test, diagnostics, status, and inventory management, and for performance monitoring. The list of managed objects applies at the DPU-NB interface shown in Figure 5-1b, relating to the "DPU-MIB" naming as used in + +[ITU-T G.9701]. The managed objects are defined to provide at least all the information necessary for translation into a YANG data model [b-IETF RFC 6020], although this does not exclude translation to other formats such as an ASN.1 (X.680 series) MIB description used in connection with SNMP [b-IETF RFC 1157]. + +The definitions of the managed objects defined in clause 7 provide the following information: + +- description; +- type; +- unit; +- valid values; +- default value (for configuration objects only); +- reference. + +The list of managed objects defined in clauses 7 and 8 also applies at the Q reference point shown in Figure 5-1a. + +# 6 Network management protocol + +This Recommendation makes no presumption about which management protocol is used between the NMS and the AN (see Figure 5-1a) or between the PMA and the DPU (see Figure 5-1b) for transport of the G.fast-managed objects. + +# 7 Managed objects + +The list of managed objects contains six types of information: + +- 1) configuration objects; +- 2) fault monitoring – failures (alarm indications); +- 3) fault monitoring – threshold crossing (alert messages); +- 4) performance monitoring objects (counters); +- 5) test, diagnostic and status objects; +- 6) inventory objects. + +Figure 7-1 shows the in-service performance monitoring process. The primitives are specified in [ITU-T G.9701]. + +![Flowchart of the in-service performance monitoring process. The process starts with 'Defect' and 'Anomaly' boxes. 'Defect' leads to 'Failure' and 'Generate parameters'. 'Anomaly' leads to 'Generate parameters'. 'Failure' leads to 'Alarm indications'. 'Generate parameters' leads to 'Current'. 'Current' leads to 'Thresholding' and 'Previous'. 'Thresholding' leads to 'Alert messages'. 'Previous' leads to 'Previous data'. A vertical double-headed arrow on the left is labeled 'Scope of ITU-T G.997.2'. A text box on the right says 'Primitives defined in ITU-TG.9701'. The diagram is labeled 'G.997.2(15)_F7-1' at the bottom right.](af6be343f0c0a8f155f965dcf337b8af_img.jpg) + +``` + +graph TD + Defect[Defect] --> Failure[Failure] + Defect --> GenParams[Generate parameters] + Anomaly[Anomaly] --> GenParams + Failure --> Alarm[Alarm indications] + GenParams --> Current[Current] + Current --> Thresholding[Thresholding] + Current --> Previous[Previous] + Thresholding --> Alert[Alert messages] + Previous --> PrevData[Previous data] + Current --> CurrData[Current data] + subgraph Scope [Scope of ITU-T G.997.2] + Defect + Anomaly + Failure + GenParams + Current + Thresholding + Previous + Alarm + Alert + CurrData + PrevData + end + Primitives[Primitives defined in ITU-TG.9701] + G9972F71[G.997.2(15)_F7-1] + +``` + +Flowchart of the in-service performance monitoring process. The process starts with 'Defect' and 'Anomaly' boxes. 'Defect' leads to 'Failure' and 'Generate parameters'. 'Anomaly' leads to 'Generate parameters'. 'Failure' leads to 'Alarm indications'. 'Generate parameters' leads to 'Current'. 'Current' leads to 'Thresholding' and 'Previous'. 'Thresholding' leads to 'Alert messages'. 'Previous' leads to 'Previous data'. A vertical double-headed arrow on the left is labeled 'Scope of ITU-T G.997.2'. A text box on the right says 'Primitives defined in ITU-TG.9701'. The diagram is labeled 'G.997.2(15)\_F7-1' at the bottom right. + +Figure 7-1 – In-service performance monitoring process + +As [ITU-T G.9701] supports a DPU with up to 128 lines, provisioning every managed object for every G.fast port on the DPU may become burdensome. Therefore, the DPU configuration management (as defined in the Broadband Forum) defines G.fast configuration profiles, as well as a mechanism to associate these profiles to the individual ports. The definition of G.fast configuration profiles is outside the scope of this Recommendation. The allocation of the individual G.fast-managed objects (as defined in this Recommendation) to G.fast configuration profiles is addressed within the scope of the Broadband Forum. + +NOTE – The "configuration profiles" are not the "Profiles" discussed in clause 6 of [ITU-T G.9701]. This clause uses the term "profile" for simplifying the configuration of [ITU-T G.9701] ports on a DPU in the field. Clause 6 of [ITU-T G.9701] is a discussion of a technique for defining the native capabilities (e.g., the particular subset of [ITU-T G.9701]) supported by a particular G.fast transceiver. + +At the DPU-NB interface, a line is configured through the following information: + +- line configuration objects (see Table 7-1) for the line; +- channel configuration objects (see Table 7-2) for the downstream channel; +- channel configuration objects (see Table 7-2) for the upstream channel; +- data path configuration objects (see Table 7-3) for the downstream data path; +- data path configuration objects (see Table 7-3) for the upstream data path. + +Line configuration objects relate to the physical media dependent (PMD) sublayer and the robust management channel (RMC). Channel configuration objects relate to the bearer channel-related aspects of the physical media specific – transmission convergence (PMS-TC) sublayer. Data path configuration objects relate to the transport protocol specific – transmission convergence (TPS-TC) sublayer. + +At the DPU-NB interface, a line is monitored through the following information: + +- line failures (see Table 7-4); +- channel failures (see Table 7-5); +- data path failures (see Table 7-6); +- line performance monitoring objects (see Table 7-7); +- channel performance monitoring objects (see Table 7-8) for the downstream channel; +- channel performance monitoring objects (see Table 7-8) for the upstream channel; +- data path performance monitoring objects (see Table 7-9) for the downstream data path; +- data path performance monitoring objects (see Table 7-9) for the upstream data path; +- line test, diagnostics and status objects (see Table 7-10); +- channel test, diagnostics and status objects (see Table 7-11) for the downstream channel; +- channel test, diagnostics and status objects (see Table 7-11) for the upstream channel; +- data path test, diagnostic and status objects (see Table 7-12) for the downstream channel; +- data path test, diagnostic and status objects (see Table 7-12) for the upstream channel; +- inventory objects (see Table 7-13). + +As [ITU-T G.9701] supports a DPU with up to 128 lines, maintaining the performance monitoring and the test, diagnostic and status information for every line may become burdensome. Although access to all mandatory managed objects shall be supported at all times for all ports on the DPU at the DPU-NB interface towards the PMA (see Figure 5-1), the objects may not be maintained within the management entity of the DPU simultaneously for all lines at all times. Although reasonable performance shall be provided at the DPU-NB interface for access to the managed objects of any line, this Recommendation does not define specific performance requirements at this interface. + +When the update request flag for a test parameter group (see clause 7.1.9) is set (its value is changed from 0 to 1), the parameters of the associated test parameter groups shall be updated in the DPU-MIB within the update time period specified in Table 7-0. The update request flag for the associated test parameter group is defined in the DPU-MIB and is independent of any autonomous update process in the system. The update request flag shall be reset (its value changed back to 0) by the DPU after the request parameter update is complete. The reset shall be within a period that is shorter than the reset time period specified in Table 7-0 to allow reception of another update request. The reset time period starts since the last time the update request flag was set (externally or by an autonomous process in the system). This applies only to the elements maintained in the DPU. + +Test parameters and status parameters shall be updated in L0, L2.1N, L2.1B and L2.2 link states, unless explicitly stated differently in [ITU-T G.9701]. The GDRds/us and ATTGDRds/us shall be updated only in L0 state. + +**Table 7-0 – Test parameter groups** + +| Test parameter group (Note) | Update time period | Reset time period | +|-------------------------------------------------------------------------------------------------------------|--------------------|-------------------| +| NE test parameter group 1 (NE-G1) | 10 seconds | 3 minutes | +| FE test parameter group 1 (FE-G1) | 15 seconds | 3 minutes | +| NE test parameter group 2 (NE-G2) | 3 minutes | 10 minutes | +| FE test parameter group 2 (FE-G2) | 3 minutes | 10 minutes | +| NOTE – The test parameters contained in each test parameter group are defined in Table 7-10 and Table 7-11. | | | + +Tables 7-1 to 7-11 indicate the status of each managed object over the DPU-NB interface: + +- R: Read only; +- W: Write only; +- R/W: Read and write; +- (M): Mandatory. If the functionality is optional in [ITU-T G.9701] and supported by the DPU, it is mandatory to include the managed object in the DPU-MIB; +- (O): Optional. + +Entries in Tables 7-1 to 7-11 labelled with names containing the separator "/" represent multiple objects whose names are obtained by considering all combinations of the elements isolated with the separator. For example, the entry labelled with the name A/B\_C/D\_E/F represents eight objects with names A\_C\_E, A\_C\_F, A\_D\_E, A\_D\_F, B\_C\_E, B\_C\_F, B\_D\_E, B\_D\_F. Also, the entry labelled with the name Ads/us represents two objects with names Ads and Aus. Near-end (-NE) objects apply to the FTU-O, while far-end (-FE) objects apply to the FTU-R. + +For each configuration managed object, a default value is defined. Configuring a managed object with a value different from the default may change the applicable valid values of other managed objects and therefore may require reconfiguration of these objects. + +**Table 7-1 – Line configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|---------------------------------------------|--------------------|------------------| +| Profiles | | | +| [ITU-T G.9701] profiles enabling (PROFILES) | 7.1.0.1 | R/W (M) | +| Time division Duplexing (TDD) | | | + +**Table 7-1 – Line configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|--------------------------------------------------------------------------|--------------------|------------------| +| Symbol periods per TDD frame (MF) | 7.1.1.1 | R/W (M) | +| Symbol periods per TDD frame dedicated for downstream transmission (Mds) | 7.1.1.2 | R/W (M) | +| Cyclic extension (CE) | 7.1.1.3 | R/W (M) | +| Power and spectrum usage | | | +| MAXATPds | 7.1.2.1 | R/W (M) | +| MAXATPus | 7.1.2.2 | R/W (M) | +| CARMASKds | 7.1.2.3 | R/W (M) | +| CARMASKus | 7.1.2.4 | R/W (M) | +| MIBPSDMASKds | 7.1.2.5 | R/W (M) | +| MIBPSDMASKus | 7.1.2.6 | R/W (M) | +| RFIBANDS | 7.1.2.7 | R/W (M) | +| IARBANDS | 7.1.2.8 | R/W (M) | +| UPBOPSDA | 7.1.2.9 | R/W (M) | +| UPBOPSDB | 7.1.2.10 | R/W (M) | +| UPBOKL | 7.1.2.11 | R/W (M) | +| UPBOKLF | 7.1.2.12 | R/W (M) | +| UPBOKLREF | 7.1.2.13 | R/W (M) | +| CLASSMASKds | 7.1.2.14 | R/W (O) | +| CLASSMASKus | 7.1.2.15 | R/W (O) | +| Noise margins | | | +| TARSNRMds | 7.1.3.1 | R/W (M) | +| TARSNRMus | 7.1.3.2 | R/W (M) | +| MAXSNRMus | 7.1.3.3 | R/W (M) | +| MINSNRMds | 7.1.3.4 | R/W (M) | +| MINSNRMus | 7.1.3.5 | R/W (M) | +| Seamless rate adaptation (SRA) | | | +| SRA-USNRMds | 7.1.4.1 | R/W (M) | +| SRA-UTIMEds | 7.1.4.2 | R/W (M) | +| SRA-USNRMus | 7.1.4.3 | R/W (M) | +| SRA-UTIMEus | 7.1.4.4 | R/W (M) | +| SRA-DSNRMds | 7.1.4.5 | R/W (M) | +| SRA-DTIMEds | 7.1.4.6 | R/W (M) | +| SRA-DSNRMus | 7.1.4.7 | R/W (M) | +| SRA-DTIMEus | 7.1.4.8 | R/W (M) | +| Fast rate adaptation (FRA) | | | +| FRA-TIMEds | 7.1.5.1 | R/W (M) | +| FRA-TIMEus | 7.1.5.2 | R/W (M) | + +**Table 7-1 – Line configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|---------------------------------------------------------------------------|--------------------|------------------| +| FRA-NTONESds | 7.1.5.3 | R/W (M) | +| FRA-NTONESus | 7.1.5.4 | R/W (M) | +| FRA-RTXUCds | 7.1.5.5 | R/W (M) | +| FRA-RTXUCus | 7.1.5.6 | R/W (M) | +| FRA-VENDISCds | 7.1.5.7 | R/W (M) | +| FRA-VENDISCus | 7.1.5.8 | R/W (M) | +| Robust management channel (RMC) | | | +| TARSNRM-RMCds | 7.1.6.1 | R/W (M) | +| TARSNRM-RMCus | 7.1.6.2 | R/W (M) | +| MINSNRM-RMCds | 7.1.6.3 | R/W (M) | +| MINSNRM-RMCus | 7.1.6.4 | R/W (M) | +| MAXBL-RMCds | 7.1.6.5 | R/W (M) | +| MAXBL-RMCus | 7.1.6.6 | R/W (M) | +| Vectoring | | | +| FEXT cancellation enabling/disabling downstream (FEXT_TO_CANCEL_ENABLEds) | 7.1.7.1 | R/W (M) | +| FEXT cancellation enabling/disabling upstream (FEXT_TO_CANCEL_ENABLEus) | 7.1.7.2 | R/W (M) | +| XLOG requested subcarrier group size (XLOGREQds) | 7.1.7.3 | R/W (O) | +| XLOG requested disturber index (XLOGDREQds) | 7.1.3.4 | R/W (O) | +| Fast-retrain policy | | | +| LOS-PERSISTENCYds | 7.1.8.1 | R/W (M) | +| LOS-PERSISTENCYus | 7.1.8.2 | R/W (M) | +| LOM-PERSISTENCYds | 7.1.8.3 | R/W (M) | +| LOM-PERSISTENCYus | 7.1.8.4 | R/W (M) | +| LOR-PERSISTENCYds | 7.1.8.5 | R/W (M) | +| LOR-PERSISTENCYus | 7.1.8.6 | R/W (M) | +| REINIT_TIME_THRESHOLDds | 7.1.8.7 | R/W (M) | +| REINIT_TIME_THRESHOLDus | 7.1.8.8 | R/W (M) | +| LOW_ETR_THRESHOLDds | 7.1.8.9 | R/W (M) | +| LOW_ETR_THRESHOLDus | 7.1.8.10 | R/W (M) | +| Update test parameters request | | | +| UPDATE-NE-TEST | 7.1.9.1 | R/W (M) | +| UPDATE-FE-TEST | 7.1.9.2 | R/W (M) | +| Low power modes | | | +| L2-TARSNRMds/us | 7.1.10.1 | R/W (M) | +| L2.1-MAXSNRMds/us | 7.1.10.2 | R/W (M) | +| L2-MAXPSDR | 7.1.10.3 | R/W (M) | + +**Table 7-1 – Line configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------|--------------------|------------------| +| L2.1-SRA-USNRMds | 7.1.10.4 | R/W(M) | +| L2.1-SRA-USNRMus | 7.1.10.5 | R/W(M) | +| L2.1-SRA-DSNRMds | 7.1.10.6 | R/W(M) | +| L2.1-SRA-DSNRMus | 7.1.10.7 | R/W(M) | +| Impulse noise monitoring (INM) | | | +| INMIATods/us | 7.1.11.1 | R/W(M) | +| INMIATSds/us | 7.1.11.2 | R/W(M) | +| INMCCds/us | 7.1.11.3 | R/W(M) | +| INM_INPEQ_FORMATds/us | 7.1.11.4 | R/W(M) | +| BRGNds/us | 7.1.11.5 | R/W(M) | +| INPEQ_SF | 7.1.11.6 | R/W(M) | +| IAT_SF | 7.1.11.7 | R/W(M) | +| INM_ENABLE | 7.1.11.8 | R/W(M) | +| RMC recovery (RMCR) | | | +| RMCR_LOR_TRIGGERds/us | 7.1.12.1 | R/W(M) | +| Showtime reconfiguration | | | +| SREC_ALLOWED | 7.1.13.1 | R/W(M) | + +**Table 7-2 – Channel configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------------|--------------------|------------------| +| Data rate (downstream/upstream) | | | +| Maximum net data rate (NDR) (MAXNDR ds/us) | 7.2.1.1 | R/W (M) | +| Minimum expected throughput (MINETRds/us) | 7.2.1.2 | R/W (M) | +| Maximum gamma data rate (GDR) (MAXGDRds/us) | 7.2.1.3 | R/W (M) | +| Minimum gamma data rate (MINGDRds/us) | 7.2.1.4 | R/W (M) | +| Retransmission (downstream/upstream) | | | +| DELAYMAXds/us | 7.2.2.1 | R/W (M) | +| INPMIN_SHINEDs/us | 7.2.2.2 | R/W (M) | +| SHINERATIods/us | 7.2.2.3 | R/W (M) | +| INPMIN_REINds/us | 7.2.2.4 | R/W (M) | +| IAT_REINds/us | 7.2.2.5 | R/W (M) | +| RNRATIods/us | 7.2.2.6 | R/W (M) | +| RTX_TESTMODE | 7.2.2.7 | R/W (M) | +| Low power modes | | | +| L2.1-MAXNDRds/us | 7.2.3.1 | R/W (M) | + +**Table 7-2 – Channel configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------------|--------------------|------------------| +| L2.2-MAXNDR | 7.2.3.2 | R/W (M) | +| L2.1-MINETRds/us | 7.2.3.3 | R/W (M) | +| L2.2-MINETR | 7.2.3.4 | R/W (M) | +| L2.1-MINETR-EXITds/us | 7.2.3.5 | R/W (M) | +| Rate threshold (downstream/upstream) | | | +| LOW-ANDEFTR-THRESHOLDds/us | 7.2.4.1 | R/W (M) | + +**Table 7-3 – Data path configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|-----------------|--------------------|------------------| +| TPS_TESTMODE | 7.3.1 | R/W (M) | +| DRA_TESTMODE | 7.3.2 | R/W (M) | + +**Table 7-4 – Line failures** + +| Category/object | Defined in clause: | DPU-NB interface | +|-----------------------------------------|--------------------|------------------| +| Near-end (FTU-O) failures | | | +| Loss of signal (LOS) | 7.4.1.1 | R (M) | +| Loss of margin (LOM) | 7.4.1.2 | R (M) | +| Loss of RMC (LOR) | 7.4.1.3 | R (M) | +| Loss of power (LPR) | 7.4.1.4 | R (M) | +| Far-end (FTU-R) failures | | | +| Far-end loss of signal (LOS-FE) failure | 7.4.2.1 | R (M) | +| Far-end loss of margin (LOM-FE) failure | 7.4.2.2 | R (M) | +| Far-end loss of RMC (LOR-FE) failure | 7.4.2.3 | R (M) | +| Far-end loss of power (LPR-FE) failure | 7.4.2.4 | R (M) | +| Initialization failures | | | +| Line init (LINIT) failure | 7.4.3.1 | R (M) | + +**Table 7-5 – Channel failures** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------|--------------------|------------------| +| Near-end (FTU-O) failures | | | +| | | | +| Far-end (FTU-R) failures | | | +| | | | + +**Table 7-6 – Data path failures** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------|--------------------|------------------| +| Near-end (FTU-O) failures | | | +| | | | +| Far-end (FTU-R) failures | | | +| | | | + +**Table 7-7 – Line performance monitoring objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|-----------------------------------------------------------------------------------------------------------------|--------------------|------------------| +| Near-end (FTU-O)/Far-end (FTU-R) performance monitoring counters (current/previous 15 min/24 h interval) | | | +| Measured time
(CURR/PREV_NE/FE_15/24_L_TIME) | 7.7.1 | R (M) | +| Invalid data flag
(PREV_NE/FE_15/24_L_INVALID) | 7.7.2 | R (M) | +| Time Stamp
(PREV_NE/FE_15/24_L_STAMP) | 7.7.3 | R (M) | +| LOS failure counter
(CURR/PREV_NE/FE_15/24_LOS) | 7.7.4 | R (M) | +| LOM failure counter
(CURR/PREV_NE/FE_15/24_LOM) | 7.7.5 | R (M) | +| LOR failure counter
(CURR/PREV_NE/FE_15/24_LOR) | 7.7.6 | R (M) | +| LPR failure counter
(CURR/PREV_NE/FE_15/24_LPR) | 7.7.7 | R (M) | +| ES counter
(CURR/PREV_NE/FE_15/24_ES) | 7.7.8 | R (M) | +| Severely errored second (SES) counter
(CURR/PREV_NE/FE_15/24_SES) | 7.7.9 | R (M) | +| LOSS counter
(CURR/PREV_NE/FE_15/24_LOSS) | 7.7.10 | R (M) | +| LOR second (LORS) counter
(CURR/PREV_NE/FE_15/24_LORS) | 7.7.11 | R (M) | + +**Table 7-7 – Line performance monitoring objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------|------------------| +| Unavailable second (UAS) counter
(CURR/PREV_NE/FE_15/24_UAS) | 7.7.12 | R (M) | +| Initialization performance monitoring counters (current/previous 15 min/24 h interval) | | | +| Full inits counter
(CURR/PREV_15/24_FULL_INITS) | 7.7.13 | R (M) | +| Failed full inits counter
(CURR/PREV_15/24_FAILEDFULL_INITS) | 7.7.14 | R (M) | +| Fast inits counter
(CURR/PREV_15/24_FAST_INITS) | 7.7.15 | R (M) | +| Failed Fast inits counter
(CURR/PREV_15/24_FAILEDFAST_INITS) | 7.7.16 | R (M) | +| Near-end (FTU-O) short interruption performance monitoring counters (current/previous 15 min/24 h interval) | | | +| LPR_INTRPT counter
(CURR/PREV_15/24_LPR_INTRPT) | 7.7.17 | R (M) | +| HRI_INTRPT counter
(CURR/PREV_15/24_HRI_INTRPT) | 7.7.18 | R (M) | +| SPONT_INTRPT counter
(CURR/PREV_15/24_SPONT_INTRPT) | 7.7.19 | R (M) | +| ME_O_INTRPT counter
(CURR/PREV_15/24_ME_O_INTRPT) | 7.7.29 | R (M) | +| Near-end (FTU-O)/far-end (FTU-R) initiated OLR/FRA performance monitoring counters (current and previous 15 min/24 h interval) | | | +| Successful bitswap counter
(CURR/PREV_NE/FE_15/24_BSW) | 7.7.20 | R (M) | +| Successful autonomous SRA counter
(CURR/PREV_NE/FE_15/24_SRA) | 7.7.21 | R (M) | +| Successful FRA counter
(CURR/PREV_NE/FE_15/24_FRA) | 7.7.22 | R (M) | +| Successful RPA counter (CURR/PREV_NE/FE_15/24_RPA) | 7.7.23 | R (M) | +| Near-end (FTU-O) performance monitoring counters (current and previous 15 min/24 h interval) | | | +| Successful transmitter-initiated gain adjustment (TIGA) counter
(CURR/PREV_15/24_TIGA) | 7.7.24 | R (M) | +| Successful SREC counter
CURR/PREV_15/24_SUCCESS_SREC | 7.7.30 | R (M) | +| Link State Usage (current and previous 15min/24h interval) | | | +| L2.1N usage counter (CURR/PREV_15/24_L2.1N) | 7.7.25 | R (M) | +| L2.1B usage counter (CURR/PREV_15/24_L2.1B) | 7.7.26 | R (M) | +| L2.2 usage counter (CURR/PREV_15/24_L2.2) | 7.7.27 | R (M) | +| Near-end (FTU-O)/far-end (FTU-R) INM performance monitoring counters (current and previous 15 min/24 h interval) | | | +| INM INPEQ histogram (CURR/PREV_NE/FE_15/24_INMINPEQ) | 7.7.28.1 | R (M) | + +**Table 7-7 – Line performance monitoring objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|--------------------------------------------------------------|--------------------|------------------| +| INM total measurement time
(CURR/PREV_NE/FE_15/24_INMAME) | 7.7.28.2 | R (M) | +| INM IAT histogram (CURR/PREV_NE/FE_15/24_INMIAT) | 7.7.28.3 | R (M) | +| INM blank frame counter (CURR/PREV_NE/FE_15/24_INMBLFC) | 7.7.28.4 | R (M) | + +**Table 7-8 – Channel performance monitoring objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------------------------------------------------------------------------------------------------------------|--------------------|------------------| +| Near-end (FTU-O)/far-end (FTU-R) performance monitoring counters (current/previous 15 min/24 h interval) | | | +| Measured Time
(CURR/PREV_NE/FE_15/24_C_TIME) | 7.8.1 | R (M) | +| Invalid Data Flag
(PREV_NE/FE_15/24_C_INVALID) | 7.8.2 | R (M) | +| Time Stamp
(PREV_NE/FE_15/24_C_STAMP) | 7.8.3 | R (M) | +| Code violation (CV) counter
(CURR/PREV_NE/FE_15/24_CV) | 7.8.4 | R (M) | +| RTXUC counter
(CURR/PREV_NE/FE_15/24_RTXUC) | 7.8.5 | R (M) | +| RTXTX counter
(CURR/PREV_NE/FE_15/24_RTXTX) | 7.8.6 | R (M) | +| LANDEFTRS counter
(CURR/PREV_NE/FE_15/24_LANDEFTRS) | 7.8.7 | R (M) | +| ANDEFTRDS counter
(CURR/PREV_NE/FE_15/24_ANDEFTRDS) | 7.8.8 | R (M) | +| Near-end (NE) and far-end (FE) rate parameters per time interval (current/previous 15 min/24 h time interval) | | | +| MINANDEFTR per time interval (MINANDEFTR
_CURR/PREV_NE/FE_15/24) | 7.8.9 | R (M) | +| MAXANDEFTR per time interval (MAXANDEFTR
_CURR/PREV_NE/FE_15/24) | 7.8.10 | R (M) | +| SUMANDEFTR per time interval (SUMANDEFTR
_CURR/PREV_NE/FE_15/24) | 7.8.11 | R (M) | +| NOTE – The Measured Time, Invalid Data Flag and Time Stamp objects may have the same values as the respective line performance monitoring objects. | | | + +**Table 7-9 – Data path performance monitoring objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|-----------------|--------------------|------------------| +| | | | + +**Table 7-10 – Line test, diagnostic and status objects** + +| Category/object | Defined in clause: | Test parameter group | DPU-NB interface | +|-----------------------------------------------------------------------|--------------------|----------------------|------------------| +| Profile | | | | +| ITU-T G.9701 profile (PROFILE) | 7.10.1.1 | Not applicable | R (M) | +| Initialization | | | | +| Initialization success/failure cause (INITSFCAUSE) | 7.10.2.1 | Not applicable | R (M) | +| Initialization last transmitted downstream signal (INITLASTSSIGNALds) | 7.10.2.2 | Not applicable | R (M) | +| Initialization last received upstream signal (INITLASTSIGNALus) | 7.10.2.3 | Not applicable | R (M) | +| Signal-to-noise ratio margin | | | | +| SNRMds | 7.10.3.1 | Not applicable | R (M) | +| SNRMus | 7.10.3.2 | Not applicable | R (M) | +| Upstream power back-off | | | | +| UPBOKLE | 7.10.4.1 | Not applicable | R (M) | +| UPBOKLE-R | 7.10.4.2 | Not applicable | R (M) | +| Actual aggregate transmit power | | | | +| ACTATPds | 7.10.5.1 | FE-G1 | R (M) | +| ACTATPus | 7.10.5.2 | NE-G1 | R (M) | +| Actual transmit power spectrum density per sub-carrier | | | | +| ACTPSDpsds | 7.10.6.1 | FE-G1 | R (M) | +| ACTPSDpsus | 7.10.6.2 | NE-G1 | R (M) | +| Channel characteristics per sub-carrier | | | | +| HLOGMTds | 7.10.1.1 | NE-G2 | R(M) | +| HLOGGds | 7.10.7.2 | NE-G2 | R(M) | +| HLOGpsds | 7.10.7.3 | NE-G2 | R(M) | +| HLOGMTus | 7.10.1.4 | NE-G2 | R (M) | +| HLOGGus | 7.10.7.5 | NE-G2 | R (M) | +| HLOGpsus | 7.10.7.6 | NE-G2 | R (M) | +| Signal-to-noise ratio per sub-carrier | | | | +| SNRMTds | 7.10.8.1 | FE-G1 | R (M) | +| SNRGds | 7.10.8.2 | FE-G1 | R (M) | +| SNRpsds | 7.10.8.3 | FE-G1 | R (M) | +| SNRMTus | 7.10.8.4 | NE-G1 | R (M) | +| SNRGus | 7.10.8.5 | NE-G1 | R (M) | +| SNRpsus | 7.10.8.6 | NE-G1 | R (M) | +| Quiet line noise per sub-carrier | | | | +| QLNMTds | 7.10.9.1 | FE-G2 | R (M) | +| QLNGds | 7.10.9.2 | FE-G2 | R (M) | +| QLNpsds | 7.10.9.3 | FE-G2 | R (M) | +| QLNMTus | 7.10.9.4 | NE-G2 | R (M) | +| QLNGus | 7.10.9.5 | NE-G2 | R (M) | +| QLNpsus | 7.10.9.6 | NE-G2 | R (M) | +| Active line noise per sub-carrier | | | | +| ALNMT | 7.10.10.1 | FE-G2 | R (M) | +| ALNG | 7.10.10.2 | FE-G2 | R (M) | + +**Table 7-10 – Line test, diagnostic and status objects** + +| Category/object | Defined in clause: | Test parameter group | DPU–NB interface | +|-------------------------------------------------------|--------------------|----------------------|------------------| +| ALNps | 7.10.10.3 | FE-G2 | R (M) | +| Low power modes | | | | +| L2.1-SNRMds | 7.10.16.1 | Not applicable | R(M) | +| L2.1-SNRMus | 7.10.16.2 | Not applicable | R(M) | +| L2.2-SNRMds | 7.10.16.3 | Not applicable | R(M) | +| L2.2-SNRMus | 7.10.16.4 | Not applicable | R(M) | +| L2-SNRM-RMCds | 7.10.16.5 | Not applicable | R(M) | +| L2-SNRM-RMCus | 7.10.16.6 | Not applicable | R(M) | +| Bit allocation per sub-carrier on data symbols | | | | +| BITSpsds | 7.10.11.1 | Not applicable | R (M) | +| BITSpsus | 7.10.11.2 | Not applicable | R (M) | +| RMC | | | | +| SNRM-RMCds | 7.10.12.1 | Not applicable | R (M) | +| SNRM-RMCus | 7.10.12.2 | Not applicable | R (M) | +| BITS-RMCpsds | 7.10.12.3 | Not applicable | R (M) | +| BITS-RMCpsus | 7.10.12.4 | Not applicable | R (M) | +| Test parameter time stamps | | | | +| STAMP-TEST-NE-G1 | 7.10.13.1 | Not applicable | R (M) | +| STAMP-TEST-FE-G1 | 7.10.13.2 | Not applicable | R (M) | +| STAMP-TEST-NE-G2 | 7.10.13.3 | Not applicable | R (M) | +| STAMP-TEST-FE-G2 | 7.10.13.4 | Not applicable | R (M) | +| OLR time stamps | | | | +| STAMP-BSWds | 7.10.14.1 | Not applicable | R (M) | +| STAMP-BSWus | 7.10.14.2 | Not applicable | R (M) | +| STAMP-SRAdS | 7.10.14.3 | Not applicable | R (M) | +| STAMP-SRAus | 7.10.14.4 | Not applicable | R (M) | +| STAMP-FRADs | 7.10.14.5 | Not applicable | R (M) | +| STAMP-FRAus | 7.10.14.6 | Not applicable | R (M) | +| STAMP-RPADs | 7.10.14.7 | Not applicable | R (M) | +| STAMP-RPAus | 7.10.14.8 | Not applicable | R (M) | +| STAMP-TIGA | 7.10.14.9 | Not applicable | R (M) | +| STAMP-SREC | 7.10.14.10 | Not applicable | R (O) | +| Signal attenuation | | | | +| SATNds | 7.10.15.1 | FE-G1 | R (M) | +| SATNus | 7.10.15.2 | NE-G1 | R (M) | +| Vectoring | | | | +| XLOGDISTds | 7.10.17.1 | NE-G2 | R (O) | +| XLOGBANDSds | 7.10.17.2 | NE-G2 | R (O) | +| XLOGpsds | 7.10.17.3 | NE-G2 | R (O) | + +**Table 7-11 – Channel test, diagnostic and status objects** + +| Category/object | Defined in clause: | Test parameter group | DPU–NB interface | +|-----------------------------------------------------------------------|--------------------|----------------------|------------------| +| Actual data rates(downstream/upstream) | | | | +| Net data rate (NDRds/us) | 7.11.1.1 | Not applicable | R (M) | +| Expected throughput (ETRds/us) | 7.11.1.2 | Not applicable | R (M) | +| Gamma data rate (GDRds/us) | 7.11.1.3 | Not applicable | R (M) | +| Attainable data rates (downstream/upstream) | | | | +| Attainable net data rate (ATTNDRds/us) | 7.11.2.1 | Not applicable | R (M) | +| Attainable expected throughput (ATTETRds/us) | 7.11.2.2 | Not applicable | R (M) | +| Attainable gamma data rate (ATTGDRds/us) | 7.11.2.3 | Not applicable | R (M) | +| Actual impulse noise protection (downstream/upstream) | | | | +| ACTINPds/us | 7.11.3.1 | Not applicable | R (M) | +| ACTINP_REINDs/us | 7.11.3.2 | Not applicable | R (M) | +| Actual framer setting (downstream/upstream) | | | | +| DTU–NFECds/us | 7.11.4.1 | Not applicable | R (M) | +| DTU–RFECds/us | 7.11.4.2 | Not applicable | R (M) | +| DTU–Qds/us | 7.11.4.3 | Not applicable | R (M) | +| Test parameters per time interval (downstream/upstream) | | | | +| Error–free bits current 15 minutes (EFB–C15Mds/us) | 7.11.5.1 | Not applicable | R (M) | +| Error–free bits previous 15 minutes (EFB–P15Mds/us) | 7.11.5.2 | Not applicable | R (M) | +| Error–free bits current 24 hours (EFB–C24Hds/us) | 7.11.5.3 | Not applicable | R (M) | +| Error–free bits previous 24 hours (EFB–P24Hds/us) | 7.11.5.4 | Not applicable | R (M) | +| MINEFTR current 15 minutes (MINEFTR_C15Mds/us) | 7.11.5.5 | Not applicable | R (M) | +| MINEFTR previous 15 minutes (MINEFTR_P15Mds/us) | 7.11.5.6 | Not applicable | R (M) | +| MINEFTR current 24 hours (MINEFTR_C24Hds/us) | 7.11.5.7 | Not applicable | R (M) | +| MINEFTR previous 24 hours (MINEFTR_P24Hds/us) | 7.11.5.8 | Not applicable | R (M) | +| Low power modes (downstream/upstream) | | | | +| L2.1-NDRds/us | 7.11.6.1 | Not applicable | R(M) | +| L2.2-NDRds/us | 7.11.6.2 | Not applicable | R(M) | +| L2.1-ETRds/us | 7.11.6.3 | Not applicable | R(M) | +| L2.2-ETRds/us | 7.11.6.4 | Not applicable | R(M) | + +**Table 7-12 – Data path test, diagnostic and status objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|-----------------|--------------------|------------------| +| | | | + +**Table 7-13 – Inventory objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|-------------------------------------------------|--------------------|------------------| +| FTU related inventory | | | +| FTU-O ITU-T G.994.1 vendor ID (FTUO_GHS_VENDOR) | 7.13.1.1 | R (M) | +| FTU-R ITU-T G.994.1 vendor ID (FTUR_GHS_VENDOR) | 7.13.1.2 | R (M) | +| FTU-O version number (FTUO_VERSION) | 7.13.1.3 | R (M) | +| FTU-R version number (FTU-R VERSION) | 7.13.1.4 | R (M) | +| FTU-O self-test result (FTUO-SELFTEST) | 7.13.1.5 | R (M) | +| FTU-R self-test result (FTUR_SELFTEST) | 7.13.1.6 | R (M) | +| ITU-T G.9701 profile support (FTUO_PROFILES) | 7.13.1.7 | R (M) | +| ITU-T G.9701 profile support (FTUR_PROFILES) | 7.13.1.8 | R (M) | +| SREC_SUPPORT_FTU_O | 7.13.1.9 | R (M) | +| SREC_SUPPORT_FTU_R | 7.13.1.10 | R (M) | +| System related inventory | | | +| DPU system vendor ID (DPU_SYSTEM_VENDOR) | 7.13.2.1 | R (M) | +| NT system vendor ID (NT_SYSTEM_VENDOR) | 7.13.2.2 | R (M) | +| DPU serial number (DPU_SYSTEM_SERIALNR) | 7.13.2.3 | R (M) | +| NT serial number (NT_SYSTEM_SERIALNR) | 7.13.2.4 | R (M) | +| VCE identifier (VCE_ID) | 7.13.2.5 | R (M) | +| VCE port index (VCE_PORT_INDEX) | 7.13.2.6 | R (M) | + +**Table 7-14 – Link state objects** + +| Category/object | Defined in clause: | DPU-NB | +|---------------------------------------------------------------------------------|--------------------|---------| +| Link State Test Configuration | | | +| Link State Force (LS-FORCED) | 7.14.1.1 | R/W (M) | +| Link State Enabling (LS-ENABLE) | 7.14.1.2 | R/W (M) | +| Link state reporting | | | +| Link State (LINK-STATE) | 7.14.2.1 | R (M) | +| Link State at update of near-end test parameter group 1 (LINK-STATE-TEST-NE-G1) | 7.14.2.2 | R (M) | +| Link State at update of far-end test parameter group 1 (LINK-STATE-TEST-FE-G1) | 7.14.2.3 | R (M) | + +## 7.1 Line configuration objects + +### 7.1.0 Profiles + +#### 7.1.0.1 ITU-T G.9701 profiles enabling (PROFILES) + +**Description:** Defines for each profile whether operation according to that profile is allowed or disallowed. + +**Type:** Array of PROFILEdescriptor[0..N-1] with N=5. + +##### PROFILEdescriptor + +**Type:** boolean. + +**Valid values:** false (disallowed) and true (allowed). + +##### Bit representation + +- 0 [ITU-T G.9701] profile 106a +- 1 [ITU-T G.9701] profile 106b +- 2 [ITU-T G.9701] profile 212a +- 3 [ITU-T G.9701] profile 106c +- 4 [ITU-T G.9701] profile 212c + +**Default value:** All elements of the array set to true (All profiles allowed). + +**Reference:** Clause 6 of [ITU-T G.9701]. + +### 7.1.1 Time division duplexing + +#### 7.1.1.1 Number of symbol periods in a TDD frame (MF) + +**Description:** Defines the total number of symbol periods in a TDD frame. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 23 and 36 + +**Default value:** 36 + +**Reference:** Clause 10.5 of [ITU-T G.9701]. + +#### 7.1.1.2 Number of downstream symbol periods in a TDD frame (Mds) + +**Description:** Defines the total number of symbol positions in a TDD frame allocated for downstream transmission. The total number of symbol positions in a TDD frame allocated for upstream transmission is calculated as $M_{us} = MF - 1 - M_{ds}$ . + +**Type:** 8-bit unsigned integer. + +**Valid values:** 10...32 (if $MF=36$ ) and 6...19 (if $MF=23$ ). + +**Default value:** 28 + +NOTE – If $MF=23$ , a value different from the default value needs to be configured (see clause 7.1). + +**Reference:** Clause 10.5 of [ITU-T G.9701]. + +#### 7.1.1.3 Cyclic extension (CE) + +**Description:** Defines the cyclic extension ( $L_{CP}$ ) to be used. + +**Type:** 8-bit unsigned integer. + +**Unit:** N/64 samples, with N = index of highest supported downstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]) plus one. + +**Valid values:** 4, 8, 10, 12, 14, 16, 20, 24, 30 and 33. + +**Default value:** 10 + +**Reference:** Clause 10.4.4 of [ITU-T G.9701]. + +### 7.1.2 Power and spectrum usage + +#### 7.1.2.1 Downstream maximum aggregate transmit power (MAXATPds) + +**Description:** Defines the maximum aggregate transmit power at the U-O2 reference point in the downstream direction during initialization and showtime (in dBm). + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dBm. + +**Valid values:** -310...+310 (-31 to +31 dBm). + +**Default value:** 40 (4 dBm). + +**Reference:** Clause 7.3.2 of [ITU-T G.9701]. + +#### 7.1.2.2 Upstream maximum aggregate transmit power (MAXATPus) + +**Description:** Defines the maximum aggregate transmit power at the U-R2 reference point in the upstream direction during initialization and showtime (in dBm). + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dBm. + +**Valid values:** -310...+310 (-31 to +31 dBm). + +**Default value:** 40 (4 dBm). + +**Reference:** Clause 7.3.2 of [ITU-T G.9701]. + +#### 7.1.2.3 Downstream sub-carrier masking (CARMASKds) + +**Description:** Defines the masked sub-carrier bands in the downstream direction. All sub-carriers within the band, i.e., with indices greater than or equal to the start sub-carrier index and less than or equal to the stop sub-carrier index, are masked, i.e., have a transmit power set to zero (linear scale). + +**Type:** Array of CARMASKdescriptor[0...N-1], with N <= 32. + +##### **CARMASKdescriptor:** + +**Type:** Record of a start sub-carrier index and a stop sub-carrier index. + +###### **Sub-carrier index:** + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0...4095 (sub-carrier index 0 to 4095). + +**Default value:** Empty array (No masked sub-carriers). + +**Reference:** Clause 6.3 of [ITU-T G.9700] and clause 7.3.1.3 of [ITU-T G.9701]. + +#### **7.1.2.4 Upstream sub-carrier masking (CARMASKus)** + +**Description:** Defines the masked sub-carrier bands in the upstream direction. All sub-carriers within the band, i.e., with indices greater than or equal to the start sub-carrier index and less than or equal to the stop sub-carrier index, have a transmit power set to zero (linear scale). + +**Type:** Array of CARMASKdescriptor[0...N-1], with N <= 32. + +**CARMASKdescriptor:** See CARMASKds in clause 7.1.2.3. + +**Default value:** Empty array (No masked sub-carriers). + +**Reference:** Clause 6.3 of [ITU-T G.9700] and clause 7.3.1.3 of [ITU-T G.9701]. + +#### **7.1.2.5 Downstream PSD mask (MIBPSDMASKds)** + +**Description:** Defines the downstream power spectral density (PSD) mask applicable at the U-O2 reference point. Requirements for a valid MIBPSDMASKds are defined in clauses 7.3.1.1.2.1 and 7.3.1.1.2.2 of [ITU-T G.9701]. + +**Type:** Array of MIBPSDMASKdescriptor[0...N-1], with N=0 or 2<=N <= 32. + +###### **PSDMASKdescriptor:** + +**Type:** Record of a sub-carrier index and a PSD level. + +###### **Sub-carrier index:** + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0...4095 (sub-carrier index 0 to 4095). + +###### **PSD level:** + +**Type:** 8-bit unsigned integer. + +**Unit:** -0.5 dBm/Hz. + +**Valid values:** 0...255 (0 to -127.5 dBm/Hz). + +**Default value:** Empty array (Limit PSD mask defined in [ITU-T G.9700]). + +**Reference:** Clause 7.3.1.1 of [ITU-T G.9701]. + +#### **7.1.2.6 Upstream PSD mask (MIBPSDMASKus)** + +**Description:** Defines the upstream PSD mask applicable at the U-R2 reference point. Requirements for a valid MIBPSDMASKus are defined in clauses 7.3.1.1.2.1 and 7.3.1.1.2.2 of [ITU-T G.9701]. + +**Type:** Array of MIBPSDMASKdescriptor[0...N-1], with N=0 or 2<=N <= 32. + +**PSDMASKdescriptor:** See MIBPSDMASKds in clause 7.1.2.5. + +**Default value:** Empty array (Limit PSD mask defined in [ITU-T G.9700]). + +**Reference:** Clause 7.3.1.1 of [ITU-T G.9701]. + +#### 7.1.2.7 RFI bands (RFIBANDS) + +**Description:** Defines the bands where the PSD shall be reduced as specified in clause 7.3.1.2 of [ITU-T G.9701]. + +**Type:** Array of RFIBANDdescriptor[0...N-1], with N $\leq$ 32. + +###### **RFIBANDdescriptor:** + +**Type:** Record of a start sub-carrier index and a stop sub-carrier index. + +###### **Sub-carrier index:** + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0...4095 (sub-carrier index 0 to 4095). + +**Default value:** Empty array (No RFI bands, no PSD reduction). + +**Reference:** Clauses 7.3.1.2 and 12.3.2.1.1 of [ITU-T G.9701]. + +#### 7.1.2.8 International amateur radio bands (IARBANDS) + +**Description:** Defines for each international amateur radio (IAR) band whether transmit PSD reduction is enabled or disabled in that band. + +**Type:** Array of IARBANDdescriptor[0...12]. + +##### **IARBANDdescriptor:** + +**Type:** boolean. + +**Valid values:** false (disabled) and true (enabled). + +###### **Bit representation:** + +| | | +|----|----------------------------------------------------| +| 0 | International amateur radio band 1800-2000 kHz | +| 1 | International amateur radio band 3500-4000 kHz | +| 2 | International amateur radio band 7000-7300 kHz | +| 3 | International amateur radio band 10100-10150 kHz | +| 4 | International amateur radio band 14000-14350 kHz | +| 5 | International amateur radio band 18068-18168 kHz | +| 6 | International amateur radio band 21000-21450 kHz | +| 7 | International amateur radio band 24890-24990 kHz | +| 8 | International amateur radio band 28000-29700 kHz | +| 9 | International amateur radio band 50000-54000 kHz | +| 10 | International amateur radio band 70000-70500 kHz | +| 11 | International amateur radio band 144000-148000 kHz | +| 12 | International amateur radio band 5351.5-5366.5 kHz | + +**Default value:** All elements of the array set to false (All IAR bands disabled, no PSD reduction). + +**Reference:** Clauses 7.3.1.2 and 12.3.2.1.1 of [ITU-T G.9701], Tables 11.70.8 and 11.70.8.1 of [ITU-T G.994.1]. + +#### 7.1.2.9 Upstream power back-off reference PSD (UPBOPSDA) + +**Description:** Defines the parameter *a* for the UPBO reference PSD used to compute the upstream power back-off for the upstream frequency band. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.01 dBm/Hz. + +**Offset:** 40 dBm/Hz. + +**Valid values:** 0...4095 (40 to 80.95 dBm/Hz). + +**Default value:** 0 (40 dBm/Hz). + +**Reference:** Clause 7.3.1.4 of [ITU-T G.9701]. + +#### **7.1.2.10 Upstream power back-off reference PSD (UPBOPSDB)** + +**Description:** Defines the parameter $b$ for the UPBO reference PSD used to compute the upstream power back-off for the upstream frequency band. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.01 dBm/Hz. + +**Valid values:** 0...4095 (0 to 40.95 dBm/Hz). + +**Default value:** 0 (0 dBm/Hz). + +**Reference:** Clause 7.3.1.4 of [ITU-T G.9701]. + +#### **7.1.2.11 Upstream electrical length (UPBOKL)** + +**Description:** Defines the electrical length $kl_0$ (expressed in dB at 1 MHz). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...1280 (0 to 128 dB). + +**Default value:** 0 (0 dB). + +**Reference:** Clause 7.3.1.4.2.1 of [ITU-T G.9701]. + +#### **7.1.2.12 Force electrical length (UPBOKLF)** + +**Description:** Defines whether or not the FTU-R is forced to use the electrical length $kl_0 = \text{UPBOKL}$ to compute the UPBOMASK. If not forced, the FTUs determine the electrical length $kl_0$ . + +**Type:** boolean. + +**Valid values:** false (not forced) and true (forced). + +**Default value:** false (not forced). + +**Reference:** Clause 7.3.1.4.2.1 of [ITU-T G.9701]. + +#### **7.1.2.13 UPBO reference electrical length per band (UPBOKLREF)** + +**Description:** Defines the UPBO reference electrical length $kl_{0\_REF}$ used to compute the upstream power back-off for the Equalized FEXT UPBO method. If $kl_{0\_REF} = 0$ (special value) then the Equal PSD UPBO method is used. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0 (special value) and 18...255 (1.8 to 25.5 dB). + +**Default value:** 0 (special value). + +**Reference:** Clause 7.3.1.4.2.2 of [ITU-T G.9701]. + +#### 7.1.2.14 Class of downstream limit masks (CLASSMASKds) + +**Description:** Defines, through a class, which limit mask can be used with each profile in the downstream direction. + +**Type:** enumeration. + +**Valid values:** 0 (classmask\_1), 1 (classmask\_2). + +**Default value:** 0 (classmask\_1). + +**Reference:** Clause 7.3.1.5 of [ITU-T G.9701]. + +#### 7.1.2.15 Class of upstream limit masks (CLASSMASKus) + +**Description:** Defines, through a class, which limit mask can be used with each profile in the upstream direction. + +**Type:** enumeration. + +**Valid values:** 0 (classmask\_1). + +**Default value:** 0 (classmask\_1). + +**Reference:** Clause 7.3.1.5 of [ITU-T G.9701]. + +### 7.1.3 Noise margin + +#### 7.1.3.1 Downstream target noise margin (TARSNRMds) + +**Description:** Defines the downstream target noise margin for the channel initialization policy. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 60 (6 dB). + +**Reference:** Clause 12.3.7 of [ITU-T G.9701]. + +#### 7.1.3.2 Upstream target noise margin (TARSNRMus) + +**Description:** Defines the upstream target noise margin used in the channel initialization policy. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 60 (6 dB). + +**Reference:** Clause 12.3.7 of [ITU-T G.9701]. + +#### 7.1.3.3 Upstream maximum noise margin (MAXSNRMus) + +**Description:** Defines the upstream maximum noise margin used in the channel initialization policy. The special value indicates there is no maximum bound for the upstream noise margin (i.e., the upstream maximum noise margin is infinite). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB) and 511 (special value). + +**Default value:** 511 (special value). + +**Reference:** Clause 12.3.7 of [ITU-T G.9701]. + +#### 7.1.3.4 Downstream minimum noise margin (MINSNRMds) + +**Description:** Defines the downstream minimum noise margin the FTU-R receiver shall tolerate. If the downstream noise margin (SNRMds) falls below this level, a loss-of-margin (*lom*) defect occurs. Upon persistency of the *lom* defect, the FTU-R triggers a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 0 (0 dB). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +#### 7.1.3.5 Upstream minimum noise margin (MINSNRMus) + +**Description:** Defines the upstream minimum noise margin the FTU-O receiver shall tolerate. If the upstream noise margin (SNRMus) falls below this level, the FTU-O requests the FTU-R to increase the FTU-R transmit power. If an increase to FTU-R transmit power is not possible, a *lom* defect occurs. Upon persistency of the *lom* defect, the FTU-O triggers a re-initialization (see clause 12.1.4.2 of [ITU-T G.9701]). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 0 (0 dB). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +### 7.1.4 Seamless rate adaptation + +#### 7.1.4.1 Downstream upshift noise margin (SRA-USNRMds) + +**Description:** If the downstream noise margin (SNRMds) is above the downstream upshift noise margin and stays above that for more than the time specified by the downstream minimum upshift rate adaptation interval (SRA-UTIMEds), the FTU-R autonomously attempts to increase the downstream net data rate (NDRds). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 70 (7 dB). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +#### 7.1.4.2 Upstream upshift noise margin (SRA-USNRMus) + +**Description:** If the upstream noise margin (SNRMus) is above the upstream upshift noise margin and stays above that for more than the time specified by the upstream minimum upshift rate adaptation interval (SRA-UTIMEus), the FTU-O autonomously attempts to increase the upstream net data rate (NDRus). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 70 (7 dB). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +#### 7.1.4.3 Downstream minimum time interval for upshift SRA (SRA-UTIMEds) + +**Description:** Defines the interval of time the downstream noise margin (SNRMds) should stay above the downstream upshift noise margin (SRA-USNRMds) before the FTU-R autonomously attempts to increase the NDRds. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 0...16383 (0 to $2^{14}-1$ s). + +**Default value:** 8 (8 s). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +#### 7.1.4.4 Upstream minimum time interval for upshift SRA (SRA-UTIMEus) + +**Description:** Defines the interval of time the upstream noise margin (SNRMus) should stay above the upstream upshift noise margin (SRA-USNRMus) before the FTU-O autonomously attempts to increase the NDRus. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 0...16383 (0 to $2^{14}-1$ s). + +**Default value:** 8 (8 s). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +##### 7.1.4.5 Downstream downshift noise margin (SRA-DSNRMds) + +**Description:** If the downstream noise margin (SNRMds) is below the downstream downshift noise margin and stays below that for more than the time specified by the downstream minimum downshift rate adaptation interval (SRA-DTIMEds), the FTU-R autonomously attempts to decrease the NDRds. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 50 (5 dB). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +##### 7.1.4.6 Upstream downshift noise margin (SRA-DSNRMus) + +**Description:** If the upstream noise margin (SNRMus) is below the upstream downshift noise margin and stays below that for more than the time specified by the upstream minimum downshift rate adaptation interval (SRA-DTIMEus), the FTU-O autonomously attempts to decrease the NDRus. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 50 (5 dB). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +##### 7.1.4.7 Downstream minimum time interval for downshift SRA (SRA-DTIMEds) + +**Description:** Defines the interval of time the downstream noise margin (SNRMds) should stay below the downstream downshift noise margin (SRA-DSNRMds) before the FTU-R autonomously attempts to decrease the NDRds. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 0...16383 (0 to $2^{14}-1$ s). + +**Default value:** 2 (2 s). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +#### 7.1.4.8 Upstream minimum time interval for downshift SRA (SRA-DTIMEus) + +**Description:** Defines the interval of time the upstream noise margin (SNRMus) should stay below the upstream downshift noise margin (SRA-DSNRMus) before the FTU-O autonomously attempts to decrease the NDRus. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 0...16383 (0 to $2^{14}-1$ s). + +**Default value:** 2 (2 s). + +**Reference:** Clause 12.3.4.2.1 of [ITU-T G.9701]. + +### 7.1.5 Fast rate adaptation + +#### 7.1.5.1 Downstream FRA time window (FRA-TIMEds) + +**Description:** Defines the duration of the time window used in the standard FRA triggering criteria (see clause 13.4.3.2 of [ITU-T G.9701]) for the downstream direction. The special value 0 indicates that vendor discretionary values for *fra-ntones*, *fra-rtx-uc* and *fra-time* may be used in the downstream direction. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 logical frame length. + +**Valid values:** 0 (special value) and (1...24 (if MF=36) or 1...36 (if MF=23)). + +**Default value:** 8 + +**Reference:** Clause 13.3.1.1.1.1 of [ITU-T G.9701]. + +#### 7.1.5.2 Upstream FRA time window (FRA-TIMEus) + +**Description:** Defines the duration of the time window used in the standard FRA triggering criteria (see clause 13.4.3.2 of [ITU-T G.9701]) for the upstream direction. The special value 0 indicates that vendor discretionary values for *fra-ntones*, *fra-rtx-uc* and *fra-time* may be used in the upstream direction. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 logical frame length. + +**Valid values:** 0 (special value) and (1...24 (if MF=36) or 1...36 (if MF=23)). + +**Default value:** 8 + +**Reference:** Clause 13.3.1.1.1.1 of [ITU-T G.9701]. + +#### 7.1.5.3 Downstream FRA minimum percentage of degraded tones (FRA-NTONESds) + +**Description:** Defines the minimum percentage of loaded sub-carriers that are detected as degraded throughout a time window equal to FRA-TIMEds in order to arm the first FRA triggering criteria (see clause 13.3.1.1.1.5 of [ITU-T G.9701]) in the downstream direction. The special value 0 indicates that monitoring of the percentage of degraded sub-carriers is disabled. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 0 and 1...100 + +**Default value:** 50 + +**Reference:** Clause 13.3.1.1.1.2 of [ITU-T G.9701]. + +#### 7.1.5.4 Upstream FRA minimum percentage of degraded tones (FRA-NTONESus) + +**Description:** Defines the minimum percentage of loaded sub-carriers (i.e., sub-carriers with $b_i > 0$ ) that are detected as degraded throughout a time window equal to FRA-TIMEus in order to arm the first FRA triggering criteria (see clause 13.3.1.1.1.5 of [ITU-T G.9701]) in the upstream direction. The special value 0 indicates that monitoring of the percentage of degraded sub-carriers is disabled. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 0 and 1...100 + +**Default value:** 50 + +**Reference:** Clause 13.3.1.1.1.2 of [ITU-T G.9701]. + +#### 7.1.5.5 Downstream FRA number of uncorrectable DTU (FRA-RTXUCds) + +**Description:** Defines the minimum number of *rtx-uc* anomalies received throughout a time window equal to FRA-TIMEds in order to arm the second FRA triggering criteria (see clause 13.3.1.1.1.5 of [ITU-T G.9701]) in the downstream direction. The special value 0 indicates that monitoring of the number of *rtx-uc* anomalies is disabled. + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0 and 1...1023 + +**Default value:** 150 + +**Reference:** Clause 13.3.1.1.1.3 of [ITU-T G.9701]. + +##### 7.1.5.6 Upstream FRA number of uncorrectable DTU (FRA-RTXUCus) + +**Description:** Defines the minimum number of *rtx-uc* anomalies received throughout a time window equal to FRA-TIMEus in order to arm the second FRA triggering criteria (see clause 13.3.1.1.1.5 of [ITU-T G.9701]) in the upstream direction. The special value 0 indicates that monitoring of the number of *rtx-uc* anomalies is disabled. + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0 and 1...1023 + +**Default value:** 150 + +**Reference:** Clause 13.3.1.1.1.3 of [ITU-T G.9701]. + +#### 7.1.5.7 Downstream vendor discretionary FRA triggering criteria (FRA-VENDISCds) + +**Description:** Defines whether vendor discretionary FRA triggering criteria may be used (enabled) or not (disabled) in the downstream direction. + +**Type:** boolean. + +**Valid values:** false (disabled) and true (enabled). + +**Default value:** false (disabled). + +**Reference:** Clause 13.3.1.1.1.4 of [ITU-T G.9701]. + +#### 7.1.5.8 Upstream vendor discretionary FRA triggering criteria (FRA-VENDISCus) + +**Description:** Defines whether vendor discretionary FRA triggering criteria may be used (enabled) or not (disabled) in the upstream direction. + +**Type:** boolean. + +**Valid values:** false (disabled) and true (enabled). + +**Default value:** false (disabled). + +**Reference:** Clause 13.3.1.1.1.4 of [ITU-T G.9701]. + +### 7.1.6 Robust management channel + +#### 7.1.6.1 Downstream target noise margin for RMC (TARSNRM-RMCds) + +**Description:** Defines the downstream RMC noise margin (SNRM-RMCds) that the FTU-R receiver shall achieve, relative to the BER requirement, or better, to successfully complete initialization. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 60 (6 dB). + +**Reference:** Clause 12.3.3.2.1 of [ITU-T G.9701]. + +#### 7.1.6.2 Upstream target noise margin (TARSNRM-RMCus) + +**Description:** Defines the upstream RMC noise margin (SNRM-RMCus) that the FTU-O receiver shall achieve, relative to the BER requirement, or better, to successfully complete initialization. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 60 (6 dB). + +**Reference:** Clause 12.3.3.2.1 of [ITU-T G.9701]. + +#### 7.1.6.3 Downstream minimum noise margin for RMC (MINSNRM-RMCds) + +**Description:** Defines the downstream minimum noise margin the FTU-R receiver tolerates for the RMC. If the downstream RMC noise margin (SNRM-RMCds) falls below this level, the FTU-R initiates the RMC parameter adjustment (RPA) procedure. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 0 (0 dB). + +**Reference:** Clause 13.2.1.3 of [ITU-T G.9701]. + +#### 7.1.6.4 Upstream minimum noise margin for RMC (MINSNRM-RMCus) + +**Description:** Defines the upstream minimum noise margin the FTU-O receiver tolerates for the RMC. If the downstream RMC noise margin (SNRM-RMCus) falls below this level, the FTU-O initiates the RPA procedure. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 0 (0 dB). + +**Reference:** Clause 13.2.1.3 of [ITU-T G.9701]. + +#### 7.1.6.5 Downstream maximum bitloading for RMC (MAXBL-RMCds) + +**Description:** Defines the maximum allowed bit-loading for the downstream RMC sub-carriers. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 2...6 + +**Default value:** 6 + +**Reference:** Clause 12.3.3.2.1 of [ITU-T G.9701]. + +#### 7.1.6.6 Upstream maximum bitloading for RMC (MAXBL-RMCus) + +**Description:** Defines the maximum allowed bit-loading for the upstream RMC sub-carriers. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 2...6 + +**Default value:** 6 + +**Reference:** Clause 12.3.3.2.1 of [ITU-T G.9701]. + +### 7.1.7 Vectoring + +#### 7.1.7.1 FEXT cancellation enabling/disabling downstream (FEXT\_TO\_CANCEL\_ENABLEds) + +**Description:** Defines whether FEXT cancellation in the downstream direction from all the other vectored lines into the line in the vectored group is enabled or disabled. + +**Type:** boolean. + +**Valid values:** false (disabled) or true (enabled). + +**Default value:** true (enabled). + +**Reference:** Clause 11.4.3.1 of [ITU-T G.9701]. + +#### 7.1.7.2 FEXT cancellation enabling/disabling upstream (FEXT\_TO\_CANCEL\_ENABLEus) + +**Description:** Defines whether FEXT cancellation in the upstream direction from all the other vectored lines into the line in the vectored group is enabled or disabled. + +**Type:** boolean. + +**Valid values:** false (disabled) or true (enabled). + +**Default value:** true (enabled). + +**Reference:** Clause 11.4.3.1 of [ITU-T G.9701]. + +#### 7.1.7.3 XLOG requested subcarrier group size (XLOGGREQds) + +**Description:** This parameter is the requested lower bound on the value of XLOGGds in the reporting of Xlogpsds + +**Type:** 8-bit signed integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4, 8, 16, 32, 64 + +**Default value:** 1 + +**Reference:** Clause 11.4.3.2 of [ITU-T G.9701]. + +#### 7.1.7.4 XLOG requested disturber index (XLOGDREQds) + +**Description:** This parameter is the requested value of the VCE\_port\_index (XLOGDISTds) for the disturber line in the reporting of XLOGpsds. + +**Type:** 16-bit unsigned integer. + +**Valid values:** 1..65535 + +**Default value:** 1 + +**Reference:** Clause 11.4.3.2 of [ITU-T G.9701]. + +### 7.1.8 Fast-retrain policy + +#### 7.1.8.1 Downstream *los* defect persistency (LOS\_PERSISTENCYds) + +**Description:** Defines the downstream *los* defect persistency for triggering a re-initialization (see clause 12.1.4.2) at the FTU-R receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 0.1 s. + +**Valid values:** 1...20 (0.1 to 2 s). + +**Default value:** 2 (0.2 s). + +**Reference:** Clause 12.1.4.3.1 of [ITU-T G.9701]. + +#### 7.1.8.2 Upstream *los* defect persistency (LOS\_PERSISTENCYus) + +**Description:** Defines the upstream *los* defect persistency for triggering a re-initialization (see clause 12.1.4.2) at the FTU-O receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 0.1 s. + +**Valid values:** 1...20 (0.1 to 2 s). + +**Default value:** 2 (0.2 s). + +**Reference:** Clause 12.1.4.3.1 of [ITU-T G.9701]. + +#### 7.1.8.3 Downstream *lom* defect persistency (LOM\_PERSISTENCYds) + +**Description:** Defines the downstream *lom* defect persistency for triggering a re-initialization (see clause 12.1.4.2) at the FTU-R receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 1...20 (1 to 20 s). + +**Default value:** 2 (2 s). + +**Reference:** Clause 12.1.4.3.2 of [ITU-T G.9701]. + +#### **7.1.8.4 Upstream *lom* defect persistency (LOM\_PERSISTENCYus)** + +**Description:** Defines the upstream *lom* defect persistency for triggering a re-initialization (see clause 12.1.4.2) at the FTU-O receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 1...20 (1 to 20 s). + +**Default value:** 2 (2 s). + +**Reference:** Clause 12.1.4.3.2 of [ITU-T G.9701]. + +#### **7.1.8.5 Downstream *lor* defect persistency (LOR\_PERSISTENCYds)** + +**Description:** Defines the downstream *lor* defect persistency for triggering a re-initialization (see clause 12.1.4.2) at the FTU-R receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 0.1 s. + +**Valid values:** 1...20 (0.1 to 2 s). + +**Default value:** 2 (0.2 s). + +**Reference:** Clause 12.1.4.3.3 of [ITU-T G.9701]. + +#### **7.1.8.6 Upstream *lor* defect persistency (LOR\_PERSISTENCYus)** + +**Description:** Defines the upstream *lor* defect persistency for triggering a re-initialization (see clause 12.1.4.2) at the FTU-O receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 0.1 s. + +**Valid values:** 1...20 (0.1 to 2 s). + +**Default value:** 2 (0.2 s). + +**Reference:** Clause 12.1.4.3.3 of [ITU-T G.9701]. + +#### **7.1.8.7 Downstream re-initialization time threshold (REINIT\_TIME\_THRESHOLDds)** + +**Description:** Defines the downstream threshold for the SES and embedded operations channel (eoc) timeout conditions for declaring a High\_BER event (see clause 12.1.4.3.4) at the FTU-R receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 5...31 (5 to 31 s). + +**Default value:** 10 (10 s). + +**Reference:** Clause 12.1.4.3.4 of [ITU-T G.9701]. + +#### **7.1.8.8 Upstream re-initialization time threshold (REINIT\_TIME\_THRESHOLDus)** + +**Description:** Defines the upstream threshold for the SES and eoc timeout conditions for declaring a High\_BER event (see clause 12.1.4.3.4) at the FTU-O receiver, as part of the fast-retrain policy. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 5...31 (5 to 31 s). + +**Default value:** 10 (10 s). + +**Reference:** Clause 12.1.4.3.4 of [ITU-T G.9701]. + +#### **7.1.8.9 Downstream low ETR threshold (LOW\_ETR\_THRESHOLDDs)** + +**Description:** Defines the downstream threshold for the low ETR condition for declaring a High\_BER event (see clause 12.1.4.3.4) at the FTU-R receiver, as part of the fast-retrain policy. The special value 0 indicates that no High\_BER event is declared based on *ETR* being below the *ETR\_min*. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 0 and 1...30 (1 to 30 s). + +**Default value:** 20 (20 s). + +**Reference:** Clause 12.1.4.3.4 of [ITU-T G.9701]. + +#### **7.1.8.10 Upstream low ETR threshold (LOW\_ETR\_THRESHOLDDus)** + +**Description:** Defines the upstream threshold for the low ETR condition for declaring a High\_BER event (see clause 12.1.4.3.4) at the FTU-O receiver, as part of the fast-retrain policy. The special value 0 indicates that no High\_BER event is declared based on *ETR* being below the *ETR\_min*. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 s. + +**Valid values:** 0 and 1...30 (1 to 30 s). + +**Default value:** 20 (20 s). + +**Reference:** Clause 12.1.4.3.4 of [ITU-T G.9701]. + +### **7.1.9 Update test parameters** + +#### **7.1.9.1 Update request flag for near-end test parameters (UPDATE-NE-TEST)** + +**Description:** Forces an update of one or more of the near-end test parameter groups that can be updated during showtime. See introductory text to clause 7. + +**Type:** Array of UPDATEREQUESTFLAGdescriptor[0..1]. + +**UPDATEREQUESTFLAGdescriptor:** + +**Type:** boolean. + +**Valid values:** false (no update forced) or true (update forced). + +**Bit representation:** + +0       Near-end test parameter group 1 (NE-G1) + +1       Near-end test parameter group 2 (NE-G2) + +**Default value:** All elements of the array set to false (no update forced). + +**Reference:** Clause 11.1 of ITU-T G.9701. + +#### 7.1.9.2 Update request flag for far-end test parameters (UPDATE-FE-TEST) + +**Description:** Forces an update of one or more of the far-end test parameter group that can be updated during showtime. See introductory text to clause 7. + +**Type:** Array of UPDATEREQUESTFLAGdescriptor[0...1]. + +**UPDATEREQUESTFLAGdescriptor:** see clause 7.1.9.1. + +###### Bit representation: + +0 Far-end test parameter group 1 (FE-G1) + +1 Far-end test parameter group 2 (FE-G2) + +**Default value:** All elements of the array set to false (no update forced). + +**Reference:** Clause 11.1 of [ITU-T G.9701]. + +### 7.1.10 Low power modes + +#### 7.1.10.1 Target noise margin in L2 (L2-TARSNRMds/us) + +**Description:** Defines the target noise margin used during the L2.1N, L2.1B and L2.2 link states. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 60 (6 dB). + +**Reference:** Clauses 13.4.1.5 and 13.4.2.5 of [ITU-T G.9701]. + +#### 7.1.10.2 Maximum noise margin in L2.1 (L2.1-MAXSNRMds/us) + +**Description:** Defines the maximum noise margin allowed during the L2.1N and L2.1B link states. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB) and 511 (special value). + +**Default value:** 511 (special value). + +**Reference:** Clauses 13.4.1.5 and 13.4.2.5 of [ITU-T G.9701]. + +#### 7.1.10.3 Maximum PSD reduction in L2 (L2-MAXPSDR) + +**Description:** Defines the maximum PSD reduction allowed during the L2.1N, L2.2B and L2.2 link states for both the upstream and downstream direction. The special value indicates there is no maximum bound for the PSD reduction (i.e., the maximum PSD reduction is infinite). + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 dB. + +**Valid values:** 0...10 (0 to 10 dB). + +**Default value:** 0 (0 dB). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +#### 7.1.10.4 Downstream upshift noise margin in L2.1 (L2.1-SRA-USNRMds) + +**Description:** If the downstream noise margin in the L2.1N and L2.1B link states (L2.1-SNRMds) is above the downstream upshift noise margin and stays above that for more than the time specified by + +the downstream minimum upshift rate adaptation interval (SRA-UTIMEds), the FTU-R autonomously attempts to increase the downstream net data rate in the L2.1 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 70 (7 dB). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +#### **7.1.10.5 Upstream upshift noise margin in L2.1 (L2.1-SRA-USNRMus)** + +**Description:** If the upstream noise margin in the L2.1N and L2.1B link states (L2.1-SNRMus) is above the upstream upshift noise margin and stays above that for more than the time specified by the upstream minimum upshift rate adaptation interval (SRA-UTIMEus), the FTU-O autonomously attempts to increase the upstream net data rate in the L2.1 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 70 (7 dB). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +#### **7.1.10.6 Downstream downshift noise margin in L2.1 (L2.1-SRA-DSNRMds)** + +**Description:** If the downstream noise margin in the L2.1N and L2.1B link states (L2.1-SNRMds) is below the downstream downshift noise margin and stays below that for more than the time specified by the downstream minimum downshift rate adaptation interval (SRA-DTIMEds), the FTU-R autonomously attempts to decrease the downstream net data rate in the L2.1 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 50 (5 dB). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +#### **7.1.10.7 Upstream downshift noise margin in L2.1 (L2.1-SRA-DSNRMus)** + +**Description:** If the upstream noise margin in the L2.1N and L2.1B link states (L2.1-SNRMus) is below the upstream downshift noise margin and stays below that for more than the time specified by the upstream minimum downshift rate adaptation interval (SRA-DTIMEus), the FTU-O autonomously attempts to decrease the upstream net data rate in the L2.1 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...310 (0 to 31 dB). + +**Default value:** 50 (5 dB). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +### 7.1.11 INM configuration objects + +The following configuration objects are defined to control the impulse noise monitor in the receive direction in the FTU. A downstream impulse noise monitor applies to the FTU-R, an upstream impulse noise monitor applies to the FTU-O. + +#### 7.1.11.1 INM inter arrival time offset (INMIATods/us) + +**Description:** Defines the inter arrival time offset per direction that the FTU receiver shall use to determine in which bin of the inter arrival time histogram the IAT is reported. + +**Type:** 16-bit unsigned integer. + +**Unit:** One IAT time unit (see clause 7.1.11.7). + +**Valid values:** 3...511 + +**Default value:** 3 + +**Reference:** Clause 11.4.4.7.2.1 of [ITU-T G.9701]. + +#### 7.1.11.2 INM inter arrival time step (INMIATSds/us) + +**Description:** Defines the inter arrival time step per direction that the FTU receiver shall use to determine in which bin of the inter arrival time histogram the IAT is reported. + +**Type:** 8-bit unsigned integer. + +**Unit:** One IAT time unit (see clause 7.1.11.7). + +**Valid values:** 0...7 + +**Default value:** 1 + +**Reference:** Clause 11.4.4.7.2.2 of [ITU-T G.9701]. + +#### 7.1.11.3 INM cluster continuation value (INMCCds/us) + +**Description:** Defines the cluster continuation value per direction that the FTU receiver shall use in the cluster indication process. + +**Type:** 8-bit unsigned integer. + +**Unit:** One DMT symbol. + +**Valid values:** 1...255. + +**Default value:** 1 + +**Reference:** Clause 11.4.4.7.2.3 of [ITU-T G.9701]. + +#### 7.1.11.4 INM equivalent INP format (INM\_INPEQ\_FORMATds/us) + +**Description:** Defines the way the scale is configured for the INM\_INPEQ histogram + +**Type:** enumeration + +**Valid values:** 0, 1 + +0        Linear scale + +1        Logarithmic scale + +**Default value:** 0 (linear scale). + +**Reference:** Clause 11.4.4.7.2.4 of [ITU-T G.9701]. + +#### 7.1.11.5 DTU cluster bridging (BRGNds/us) + +**Description:** Defines per direction whether the FTU receiver shall use bridging in the determination of the DTU cluster size. + +**Type:** Boolean. + +**Valid values:** False (disabled), True (enabled). + +**Default value:** False (disabled). + +**Reference:** Clause 11.4.4.7.2.5 of [ITU-T G.9701]. + +#### 7.1.11.6 INPEQ Time Unit Scaling Factor (INPEQ\_SF) + +**Description:** Defines time unit scaling factor for the line that the FTU receivers shall use for reporting INPEQ. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 4, 8, 12 + +**Default value:** 12 + +**Reference:** Clause 11.4.4.7.2.6 of [ITU-T G.9701]. + +#### 7.1.11.7 IAT time unit scaling factor (IAT\_SF) + +**Description:** Defines the time unit scaling factor for the line that the FTU receivers shall use for reporting IAT. One IAT time unit is defined as ST DMT symbols. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 4, 8, 12 + +**Default value:** 12 + +**Reference:** Clause 11.4.4.7.2.7 of [ITU-T G.9701]. + +#### 7.1.11.8 INM enable (INM\_ENABLE) + +**Description:** Defines whether the INM functionality is enabled or disabled. + +**Type:** Boolean + +**Valid values:** False (disabled), True (enabled). + +**Default value:** False (disabled). + +**Reference:** Clause 11.4.4.7 of [ITU-T G.9701]. + +### 7.1.12 RMCR configuration objects + +The following configuration objects are defined to control the RMCR procedure in the receive direction in the FTU. + +#### 7.1.12.1 RMCR *lor* persistency trigger (RMCR\_LOR\_TRIGGERds/us) + +**Description:** Defines the persistency period of a *lor* defect before the RMC is declared severely degraded. The value 0 is a special value that indicates that the RMCR procedure is disabled. It can only be set to 0 in one direction if the value is also set to 0 in the opposite direction. + +**Type:** 8-bit unsigned integer. + +**Unit:** 50 ms. + +**Valid values:** 0 (disabled), 1(50 ms), ..., 20 (1000 ms) + +**Default value:** (0disabled) + +**Reference:** Clause 13.3.1.2.1 of [ITU-T G.9701]. + +### 7.1.13 Showtime reconfiguration configuration objects + +The following configuration objects are defined to control the Showtime reconfiguration (SREC) procedures. + +#### 7.1.13.1 SRECalloed (SREC\_ALLOWED) + +**Description:** Indicates whether the SREC procedures shall not be used (SREC\_allowed = false), or the SREC procedures may be used (SREC\_allowed = true) to force a new configuration onto the line. The conditions to use the SREC procedures are specified in Annex R of [ITU-T G.9701]. + +**Type:** boolean. + +**Valid values:** false (not allowed) and true (allowed). + +**Default value:** false. + +**Reference:** Annex R of [ITU-T G.9701]. + +## 7.2 Channel configuration objects + +### 7.2.1 Data rates + +#### 7.2.1.1 Maximum net data rate (MAXNDRds/us) + +**Description:** Defines the value of the maximum NDR (see clause 11.4.2.2 of [ITU-T G.9701]). + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 4294967295 (4294967295 kbit/s). + +**Reference:** Clause 11.4.2.2 of [ITU-T G.9701]. + +#### 7.2.1.2 Minimum expected throughput (MINETRds/us) + +**Description:** Defines the value of the minimum expected throughput (see clause 11.4.2.1 of [ITU-T G.9701]). + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 bit/s). + +**Reference:** Clause 11.4.2.1 of [ITU-T G.9701]. + +#### 7.2.1.3 Maximum gamma data rate (MAXGDRds/us) + +**Description:** Defines the maximum value of the gamma data rate (GDR) (see clause 7.11.1.3). The GDR shall not exceed MAXGDR at the start of showtime and during showtime. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 4294967295 (4294967295 kbit/s). + +**Reference:** None. + +#### 7.2.1.4 Minimum gamma data rate (MINGDRds/us) + +**Description:** Defines the minimum value of the GDR (see clause 7.11.1.3). The GDR may be less than MINGDR. If the GDR is less than MINGDR at initialization or when GDR becomes less than MINGDR during showtime, a threshold crossing alert occurs. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 bits/second). + +**Reference:** None. + +### 7.2.2 Retransmission + +#### 7.2.2.1 Maximum delay (DELAYMAXds/us) + +**Description:** Defines the maximum allowed delay for retransmission (see clause 9.8 of [ITU-T G.9701]). The ITU-T G.9701 control parameter *delay\_max* is set to the same value as the maximum delay (see clause 11.4.2.3 of [ITU-T G.9701]). + +**Type:** 32-bit unsigned integer. + +**Unit:** 0.25 ms. + +**Valid values:** 4..64 (1 to 16 milliseconds). + +**Default value:** 40 (10 ms). + +**Reference:** Clause 11.4.2.3 of [ITU-T G.9701]. + +#### 7.2.2.2 Minimum impulse noise protection against SHINE (INPMIN\_SHINEds/us) + +**Description:** Defines the minimum impulse noise protection against SHINE (see clause 9.8 of [ITU-T G.9701]). The ITU-T G.9701 control parameter *INP\_min\_shine* is set to the same value as the minimum impulse noise protection against SHINE (see clause 11.4.2.4 of [ITU-T G.9701]). + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol period. + +**Valid values:** 0...520 (0 to 520 symbol periods). + +**Default value:** 0 (0 symbol periods). + +**Reference:** Clause 11.4.2.4 of [ITU-T G.9701]. + +#### 7.2.2.3 SHINE ratio (SHINERATIOds/us) + +**Description:** Defines the *SHINERatio* that is used in the definition of the expected throughput rate (*ETR*) (see clause 9.8 of [ITU-T G.9701]). The ITU-T G.9701 control parameter *SHINERatio* is set to the same value as the SHINE ratio (see clause 11.4.2.5 of [ITU-T G.9701]). + +**Type:** 8-bit unsigned integer. + +**Unit:** 0.001 + +**Valid values:** 0...100 (0 to 0.1) + +**Default value:** 0 (0) + +**Reference:** Clause 11.4.2.5 of [ITU-T G.9701]. + +#### 7.2.2.4 Minimum impulse noise protection against REIN (INPMIN\_REINds/us) + +**Description:** Defines the minimum impulse noise protection against repetitive electrical impulse noise (REIN) (see clause 9.8 of [ITU-T G.9701]). The ITU-T G.9701 control parameter *INP\_min\_rein* is set to the same value as the minimum impulse noise protection against REIN (see clause 11.4.2.6 of [ITU-T G.9701]). + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 symbol period. + +**Valid values:** 0...63 (0 to 63 symbol periods). + +**Default value:** 0 (0 symbol periods). + +**Reference:** Clause 11.4.2.6 of [ITU-T G.9701]. + +#### 7.2.2.5 REIN inter-arrival time (IAT\_REINds/us) + +**Description:** Defines the REIN inter-arrival time (see clause 9.8 of [ITU-T G.9701]). The ITU-T G.9701 control parameter *iat\_rein\_flag* is set to the same value as the REIN inter-arrival time (see clause 11.4.2.7 of [ITU-T G.9701]). + +**Type:** enumeration. + +**Valid values:** 0 (100 Hz), 1 (120 Hz), 2 (300 Hz), 3 (360 Hz). + +**Default value:** 0 (100 Hz) + +**Reference:** Clause 11.4.2.7 of [ITU-T G.9701]. + +#### 7.2.2.6 Minimum Reed-Solomon RFEC/NFEC ratio (RNRATIOds/us) + +**Description:** Defines the minimal required ratio, RFEC/NFEC, of Reed-Solomon code parameters. The ITU-T G.9701 control parameter *rnratio* is set to the same value as the minimum Reed-Solomon RFEC/NFEC ratio (see clause 11.4.2.8 of [ITU-T G.9701]). + +**Type:** 8-bit unsigned integer. + +**Unit:** 1/32 + +**Valid values:** 0...8 (0 to 1/4) + +**Default value:** 0 (0) + +**Reference:** Clause 11.4.2.8 of [ITU-T G.9701]. + +#### 7.2.2.7 RTX-TC testmode (RTX\_TESTMODE) + +**Description:** Defines whether the retransmission testmode defined in clause 9.8.3.1.2 of [ITU-T G.9701] is enabled or disabled in the upstream and downstream directions. The RTX\_TESTMODE setting may be changed during showtime. When changed, it shall take effect on the line within 2 s without re-initialization. + +**Type:** boolean. + +**Valid values:** false (disabled) or true (enabled). + +**Default value:** false (disabled). + +**Reference:** Clause 9.8.3.1.2 of [ITU-T G.9701]. + +### 7.2.3 Low power modes + +#### 7.2.3.1 Maximum net data rate in L2.1 (L2.1-MAXNDRds/us) + +**Description:** Defines the value of the maximum net data rate allowed during the L2.1N and L2.1B link states. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 4294967295 (4294967295 kbits/second). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +#### 7.2.3.2 Maximum net data rate in L2.2 (L2.2-MAXNDR) + +**Description:** Defines the value of the maximum net data rate allowed during the L2.2 link state for both the upstream and downstream direction. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbits/s). + +**Default value:** 4294967295 (4294967295 kbits/second). + +**Reference:** Clause 13.4.2.5 of [ITU-T G.9701]. + +#### 7.2.3.3 Minimum expected throughput in L2.1 (L2.1-MINETRds/us) + +**Description:** Defines the value of the minimum expected throughput allowed during the L2.1N and L2.1B link states. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 bits/second). + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +#### 7.2.3.4 Minimum expected throughput in L2.2 (L2.2-MINETR) + +**Description:** Defines the value of the minimum expected throughput allowed during the L2.2 link state for both the upstream and downstream direction. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 bits/second). + +**Reference:** Clause 13.4.2.5 of [ITU-T G.9701]. + +#### 7.2.3.5 Minimum expected throughput after exit from L2.1 (L2.1-MINETR-EXITds/us) + +**Description:** Defines the value of the minimum expected throughput allowed after exit from the L2.1N to the L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 bits/second) + +**Reference:** Clause 13.4.1.5 of [ITU-T G.9701]. + +### 7.2.4 Rate threshold + +#### 7.2.4.1 "landeftr" defect threshold (LOW-ANDEFTR-THRESHOLDDs/us) + +**Description:** Defines the value of the low all-normal operation interval (NOI) data error-free throughput rate threshold (see clause 11.3.1.3 of [ITU-T G.9701]). + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 kbit/s) + +**Reference:** Clause 11.3.1.3 of [ITU-T G.9701]. + +## 7.3 Data path configuration objects + +### 7.3.1 TPS-TC testmode (TPS\_TESTMODE) + +**Description:** Defines whether the TPS-TC testmode defined in clause 8.3.1 of [ITU-T G.9701] is enabled or disabled in the upstream and downstream directions. The TPS\_TESTMODE setting may be changed during showtime. When changed, it shall take effect on the line within 2 s without re-initialization. + +**Type:** boolean. + +**Valid values:** false (disabled) or true (enabled). + +**Default value:** false (disabled). + +**Reference:** Clause 8.3.1 of [ITU-T G.9701]. + +### 7.3.2 DRA testmode (DRA\_TESTMODE) + +**Description:** Defines whether the dynamic resource allocation (DRA) testmode defined in clause 9.8.3.1.2 of [ITU-T G.9701] is enabled or disabled in the upstream and downstream directions. The DRA\_TESTMODE setting may be changed during showtime. When changed, it shall take effect on the line within 2 s without re-initialization. + +**Type:** boolean. + +**Valid values:** false (disabled) or true (enabled). + +**Default value:** false (disabled). + +**Reference:** Clause 9.8.3.1.2 of [ITU-T G.9701]. + +## 7.4 Line failures + +Any failure defined in this clause shall be conveyed by the DPU over the DPU-NB interface and may be conveyed by the NT over the T-/S-interface after it is detected. + +The near-end failure detections shall be provided at the DPU and may be provided at the NT. + +The far-end failure detections shall be provided at the DPU (NT is at the far-end), and may be provided at the NT (DPU is at the far-end). + +### 7.4.1 Near end failures + +The LOS, LOR, and LOM failures are mutually exclusive and reflect the reason cause of the triggered re-initialization. If no LOS, LOR, or LOM failure is declared, then the re-initialization is triggered by a High\_BER event (see clause 12.1.4 of [ITU-T G.9701]). + +#### 7.4.1.1 Loss-of-signal (LOS) failure + +A LOS failure is declared when a re-initialization is triggered by a persistent near-end *los* defect. A LOS failure is cleared immediately at the start of showtime in the receiving direction. + +#### 7.4.1.2 Loss-of-RMC (LOR) failure + +A LOR failure is declared when a re-initialization is triggered by a persistent near-end *lor* defect. A LOR failure is cleared immediately at the start of showtime in the receiving direction. + +#### 7.4.1.3 Loss-of-margin (LOM) failure + +A LOM failure is declared when a re-initialization is triggered by a persistent near-end *lom* defect. A LOM failure is cleared immediately at the start of showtime in the receiving direction. + +#### 7.4.1.4 Loss of power failure + +A LPR failure is declared after $2.5 \pm 0.5$ s of contiguous near-end *lpr* primitive presence. An LPR failure is cleared after $10 \pm 0.5$ s of no near-end *lpr* primitive presence. + +### 7.4.2 Far-end failures + +#### 7.4.2.1 Far-end loss of signal failure + +A LOS-FE failure is declared when a re-initialization is triggered with a far-end *los* defect present. A LOS-FE failure is cleared immediately at the start of showtime in the transmitting direction. + +#### 7.4.2.2 Far-end loss of RMC failure + +A LOR-FE failure is declared when a re-initialization is triggered with a far-end *lor* defect present and no LOS-FE failure is present. A LOR-FE failure is cleared immediately at the start of showtime in the transmitting direction. + +#### 7.4.2.3 Far-end loss of margin failure + +A LOM-FE failure is declared when a re-initialization is triggered with a far-end *lom* defect present and no LOS-FE failure is present and no LOR-FE failure is present. A LOM-FE failure is cleared immediately at the start of showtime in the transmitting direction. + +#### 7.4.2.4 Far-end loss of power failure + +A LPR-FE failure is declared after the occurrence of a far-end *lpr* primitive followed by $2.5 \pm 0.5$ s of contiguous near-end *los* defect. A LPR-FE failure is cleared after $10 \pm 0.5$ s of no near-end *los* defect. + +### 7.4.3 Initialization failures + +#### 7.4.3.1 Line initialization (LINIT) failure + +When the near-end transmitter enters the SILENT state and fails to reach the SHOWTIME state (after a vendor discretionary number of retries and/or within a vendor discretionary timeout), then an initialization failure occurs. An initialization failure cause and last successful transmitted state are reported (see clause 7.10.2). + +## 7.5 Channel failures + +No channel failures are defined. + +## 7.6 Data path failures + +No data path failures are defined. + +## 7.7 Line performance monitoring objects + +The line performance monitoring objects defined in Table 7-7 are subject to the rules defined in clause 8. + +CURR/PREV means that the object may apply separately for the current interval and the previous interval, NE/FE means that the object may apply separately for network element (NE) and FE, and 15/24 means that the object may apply separately for 15 min and 24 h intervals. + +### 7.7.1 Measured Time (CURR/PREV\_NE/FE\_15/24\_L\_TIME) + +**Description:** Reports the amount of time, measured in seconds, that statistics for this interval have been counted. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0..900 (for 15 min interval) and 0..86400 (for 24 h interval). + +**Reference:** Clause 8.9. + +### 7.7.2 Invalid Data flag (PREV\_NE/FE\_15/24\_L\_INVALID) + +**Description:** Reports the validity of the corresponding PM data. Reported only with the previous interval PM counters. + +**Type:** boolean. + +**Valid values:** TRUE (PM data is incomplete or invalid) and FALSE (PM data is complete and valid). + +**Reference:** Clause 8.9. + +### 7.7.3 Time Stamp (PREV\_NE/FE\_15/24\_L\_STAMP) + +**Description:** Reports the start date/time for this interval. Reported only with the previous interval PM counters. + +**Type:** String (as defined in clause 8.12). + +**Reference:** None. + +### 7.7.4 LOS failure counter (CURR/PREV\_NE/FE\_15/24\_LOS) + +**Description:** For NE, reports a count of the LOS failures defined in clause 7.4.1.1. For FE, reports a count of the LOS-FE failures defined in clause 7.4.2.1. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0..4294967295 (event counter). + +**Reference:** Clauses 7.4.1.1 and 7.4.2.1. + +### 7.7.5 LOR failure counter (CURR/PREV\_NE/FE\_15/24\_LOR) + +**Description:** For NE, reports a count of the LOR failures defined in clause 7.4.1.2. For FE, reports a count of the LOR-FE failures defined in clause 7.4.2.2. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0..4294967295 (event counter). + +**Reference:** Clauses 7.4.1.2 and 7.4.2.2. + +### **7.7.6 LOM failure counter (CURR/PREV\_NE/FE\_15/24\_LOM)** + +**Description:** For NE, reports a count of the LOM failures defined in clause 7.4.1.3. For FE, reports a count of the LOM-FE failures defined in clause 7.4.2.3. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clauses 7.4.1.3 and 7.4.2.3. + +### **7.7.7 LPR failure counter (CURR/PREV\_NE/FE\_15/24\_LPR)** + +**Description:** For NE, reports a count of the LPR failures defined in clause 7.4.1.4. For FE, reports a count of the LPR-FE failures defined in clause 7.4.2.4. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clauses 7.4.1.4 and 7.4.2.4. + +### **7.7.8 ES counter (CURR/PREV\_NE/FE\_15/24\_ES)** + +**Description:** Reports the count of errored seconds (ESs). An ES is defined in clause 11.4.4.2 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.4.2 of [ITU-T G.9701]. + +### **7.7.9 SES counter (CURR/PREV\_NE/FE\_15/24\_SES)** + +**Description:** Reports the count of SESs. An SES is defined in clause 11.4.4.3 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.4.3 of [ITU-T G.9701]. + +### **7.7.10 LOSS counter (CURR/PREV\_NE/FE\_15/24\_LOSS)** + +**Description:** Reports the count of LOS seconds (LOSS). A LOSS is defined in clause 11.4.4.4 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.4.4 of [ITU-T G.9701]. + +### **7.7.11 LORS counter (CURR/PREV\_NE/FE\_15/24\_LORS)** + +**Description:** Reports the count of LORS. A LORS is defined in clause 11.4.4.5 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.4.5 of [ITU-T G.9701]. + +### **7.7.12 UAS counter (CURR/PREV\_NE/FE\_15/24\_UAS)** + +**Description:** Reports the count of unavailable seconds (UAS). An unavailable second (UAS) is defined in clause 11.4.4.6 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.4.6 of [ITU-T G.9701]. + +### **7.7.13 Full inits counter (CURR/PREV\_15/24\_FULL\_INITS)** + +**Description:** Reports a count of the full initialization primitives (*full\_init*). The full initialization primitive (*full\_init*) is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.5 of [ITU-T G.9701]. + +### **7.7.14 Failed full inits counter (CURR/PREV\_15/24\_FAILEDFULL\_INITS)** + +**Description:** Reports a count of the failed full initialization primitives (*failedfull\_init*). The failed full initialization primitive (*failedfull\_init*) is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.5 of [ITU-T G.9701]. + +### **7.7.15 Fast inits counter (CURR/PREV\_15/24\_FAST\_INITS)** + +**Description:** Reports a count of the fast initialization primitives (*fast\_init*). The fast initialization primitive (*fast\_init*) is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.5 of [ITU-T G.9701]. + +### **7.7.16 Failed fast inits counter (CURR/PREV\_15/24\_FAILEDFAST\_INITS)** + +**Description:** Reports a count of the failed fast initialization primitives (*failedfast\_init*). The failed fast initialization primitive (*failedfast\_init*) is defined in clause 11.3.1.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.5 of [ITU-T G.9701]. + +### **7.7.17 LPR\_INTRPT counter (CURR/PREV\_15/24\_LPR\_INTRPT)** + +**Description:** Reports a count of the loss-of-power interruption anomalies (*lpr\_intrpt*). The loss-of-power interruption anomaly (*lpr\_intrpt*) is defined in clause 11.3.1.1 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.1 of [ITU-T G.9701]. + +### 7.7.18 HRI\_INTRPT counter (CURR/PREV\_15/24\_HRI\_INTRPT) + +**Description:** Reports a count of the host-reinit interruption anomalies (*hri\_intrpt*). The host-reinit interruption anomaly (*hri\_intrpt*) is defined in clause 11.3.1.1 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.1 of [ITU-T G.9701]. + +### 7.7.19 SPONT\_INTRPT counter (CURR/PREV\_15/24\_SPONT\_INTRPT) + +**Description:** Reports a count of the spontaneous interruption anomalies (*spont\_intrpt*). The spontaneous interruption anomaly (*spont\_intrpt*) is defined in clause 11.3.1.1 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.1 of [ITU-T G.9701]. + +### 7.7.20 Successful bit swap counter (CURR/PREV\_NE/FE\_15/24\_BSW) + +**Description:** Reports a count of the successful bit swap primitives (*success\_BSW*). The successful bit swap primitive (*success\_BSW*) is defined in clause 11.3.1.6 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.6 of [ITU-T G.9701]. + +### 7.7.21 Successful autonomous SRA (CURR/PREV\_NE/FE\_15/24\_SRA) + +**Description:** Reports a count of the successful autonomous SRA primitives (*success\_SRA*). The successful autonomous SRA primitive (*success\_SRA*) is defined in clause 11.3.1.6 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.6 of [ITU-T G.9701]. + +### 7.7.22 Successful FRA counter (CURR/PREV\_NE/FE\_15/24\_FRA) + +**Description:** Reports a count of the successful FRA primitives (*success\_FRA*). The successful FRA primitive (*success\_FRA*) is defined in clause 11.3.1.6 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.6 of [ITU-T G.9701]. + +### 7.7.23 Successful RPA counter (CURR/PREV\_NE/FE\_15/24\_RPA) + +**Description:** Reports a count of the successful RPA primitives (*success\_RPA*). The successful RPA primitive (*success\_RPA*) is defined in clause 11.3.1.6 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.6 of [ITU-T G.9701]. + +### **7.7.24 Successful TIGA counter (CURR/PREV\_15/24\_TIGA)** + +**Description:** Reports a count of the successful TIGA primitives (*success\_TIGA*). The successful TIGA primitive (*success\_TIGA*) is defined in clause 11.3.1.6 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.6 of [ITU-T G.9701]. + +### **7.7.25 L2.1N usage counter (CURR/PREV\_15/24\_L2.1N)** + +**Description:** Reports the count of L2.1N link state seconds (L2.1NSs). An L2.1NS is defined in clause 12.1.1.1 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1 second. + +**Valid values:** 0...86400 (0 to 86400 s). + +**Reference:** Clause 12.1.1.1 of [ITU-T G.9701]. + +### **7.7.26 L2.1B usage counter (CURR/PREV\_15/24\_L2.1B)** + +**Description:** Reports the count of L2.1B link state seconds (L2.1BSs). An L2.1BS is defined in clause 12.1.1.1 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1 second. + +**Valid values:** 0...86400 (0 to 86400 s). + +**Reference:** Clause 12.1.1.1 of [ITU-T G.9701]. + +### **7.7.27 L2.2 usage counter (CURR/PREV\_15/24\_L2.2)** + +**Description:** Reports the count of L2.2 link state seconds (L2.2Ss). An L2.2S is defined in clause 12.1.1.1 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1 second. + +**Valid values:** 0...86400 (0 to 86400 s). + +**Reference:** Clause 12.1.1.1 of [ITU-T G.9701]. + +### **7.7.28 INM performance monitoring objects** + +#### **7.7.28.1 INM INPEQ histogram (CURR/PREV\_NE/FE\_15/24\_INMINPEQ)** + +**Description:** Reports the count of the INMAINPEQi anomalies occurring on the line during the accumulation period. + +**Type:** Array of INPEQBINdescriptor[1...17]. The bin with index i shall include the count of INMAINPEQi anomalies. + +**INPEQBINdescriptor:** + +- **Type:** 32-bit unsigned integer. +- **Valid values:** 0...232–1 + +**Reference:** Clause 11.4.4.7.3.1 of [ITU-T G.9701]. + +#### 7.7.28.2 INM total measurement (CURR/PREV\_NE/FE\_15/24\_INMAME) + +**Description:** Reports the count of the INMAME anomalies occurring on the line during the accumulation period. + +**Type:** 32-bit unsigned integer. + +**Valid values:** $0 \dots 2^{32}-1$ + +**Reference:** Clause 11.4.4.7.3.2 of [ITU-T G.9701]. + +#### 7.7.28.3 INM IAT histogram (CURR/PREV\_NE/FE\_15/24\_INMIAT) + +**Description:** Reports the count of the INMAIATi anomalies occurring on the line during the accumulation period. + +**Type:** Array of IATBINdescriptor[0...7]. The bin with index i shall include the count of INMAIATi anomalies. + +##### IATBINdescriptor: + +- **Type:** 32-bit unsigned integer. +- **Valid values:** $0 \dots 2^{32}-1$ + +**Reference:** Clause 11.4.4.7.3.3 of [ITU-T G.9701]. + +#### 7.7.28.4 INM blank frame counter (CURR/PREV\_NE/FE\_15/24\_INMBLFCds/us) + +**Description:** Reports the count of the INMBLFC anomalies occurring on the line during the accumulation period. + +**Type:** 32-bit unsigned integer. + +**Valid values:** $0 \dots 2^{32}-1$ + +**Reference:** Clause 11.4.4.7.3.4 of [ITU-T G.9701]. + +### 7.7.29 Reinitializations due to ME-O trigger counter (CURR/PREV\_15/24\_ME\_O\_INTRPT) + +**Description:** Reports a count of *me\_o\_intrpt* anomalies. The *me\_o\_intrpt* anomaly is defined in clause R.5 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** $0 \dots 2^{32}-1$ (event counter). + +**Reference:** Clause R.5 of [ITU-T G.9701]. + +### 7.7.30 Successful SREC counter (CURR/PREV\_15/24\_SUCCESS\_SREC) + +**Description:** Reports a count of *success\_srec* primitives. The *success\_srec* primitive is defined in clause R.3 of [ITU-T G.9701]. Reported only with the near-end PM counters. + +**Type:** 32-bit unsigned integer. + +**Valid values:** $0 \dots 2^{32}-1$ (event counter). + +**Reference:** Annex R of [ITU-T G.9701]. + +## 7.8 Channel performance monitoring objects + +The channel performance monitoring objects defined in Table 7-8 are subject to the rules defined in clause 8. + +### **7.8.1 Measured Time (CURR/PREV\_NE/FE\_15/24\_C\_TIME)** + +**Description:** Reports the amount of time, measured in seconds, that statistics for this interval have been counted. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (for 15 min interval) and 0...86400 (for 24 h interval). + +**Reference:** Clause 8.9. + +### **7.8.2 Invalid Data Flag (PREV\_NE/FE\_15/24\_C\_INVALID)** + +**Description:** Reports the validity of the corresponding PM data. Reported only with the previous interval PM counters. + +**Type:** boolean. + +**Valid values:** TRUE (PM data is incomplete or invalid) and FALSE (PM data is complete and valid). + +**Reference:** Clause 8.9. + +### **7.8.3 Time Stamp (PREV\_NE/FE\_15/24\_C\_STAMP)** + +**Description:** Reports the start date/time for this interval. Reported only with the previous interval PM counters. + +**Type:** String (as defined in clause 8.12). + +**Reference:** None. + +### **7.8.4 CV counter (CURR/PREV\_NE/FE\_15/24\_CV)** + +**Description:** Reports a count of cyclic redundancy check (CRC) anomalies. The CRC anomaly is defined in clause 11.3.1.1 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.1 of [ITU-T G.9701]. + +### **7.8.5 Uncorrected DTU counter (CURR/PREV\_NE/FE\_15/24\_RTXUC)** + +**Description:** Reports a count of the uncorrected DTU anomalies (*rtx-uc*). The uncorrected DTU anomaly (*rtx-uc*) is defined in clause 11.3.1.1 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.1 of [ITU-T G.9701]. + +### **7.8.6 Retransmitted DTU counter (CURR/PREV\_NE/FE\_15/24\_RTXX)** + +**Description:** Reports a count of the retransmitted DTU anomalies (*rtx-tx*). The retransmitted DTU anomaly (*rtx-tx*) is defined in clause 11.3.1.1 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (event counter). + +**Reference:** Clause 11.3.1.1 of [ITU-T G.9701]. + +### **7.8.7 LANDEFTRS counter (CURR/PREV\_NE/FE\_15/24\_LANDEFTRS)** + +**Description:** Reports the count of LANDEFTRS seconds. A LANDEFTRS second is defined in clause 11.4.4.8 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.4.8 of [ITU-T G.9701]. + +### **7.8.8 ANDEFTRDS counter (CURR/PREV\_NE/FE\_15/24\_ANDEFTRDS)** + +**Description:** Reports the count of All NOI with Data symbols EFTR defined seconds (ANDEFTRDSs). An ANDEFTRDS is defined in clause 11.4.1.1.25 of [ITU-T G.9701]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...900 (15 min interval) and 0...86400 (24 h interval). + +**Reference:** Clause 11.4.1.1.25 of [ITU-T G.9701]. + +### **7.8.9 Minimum All NOI with Data symbols EFTR per time interval (MINANDEFTR\_CURR/PREV\_NE/FE\_15/24)** + +**Description:** Reports the minimum All NOI with Data symbols EFTR (see clause 11.4.1.1.22 of [ITU-T G.9701]) over the associated time interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Reference:** Clause 11.4.1.1.22 of [ITU-T G.9701]. + +### **7.8.10 Maximum All NOI with Data symbols EFTR per time interval (MAXANDEFTR\_CURR/PREV\_NE/FE\_15/24)** + +**Description:** Reports the maximum All NOI with Data symbols EFTR (see clause 11.4.1.1.23 of [ITU-T G.9701]) over the associated time interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Reference:** Clause 11.4.1.1.23 of [ITU-T G.9701]. + +### **7.8.11 Sum All NOI with Data symbols EFTR per time interval (SUMANDEFTR\_CURR/PREV\_NE/FE\_15/24)** + +**Description:** Reports the sum of All NOI with Data symbols EFTR bits (see clause 11.4.1.1.24 of [ITU-T G.9701]), divided by 65536, over the associated time interval. + +Note – SUMANDEFTR and ANDEFTRDS can be used to compute the mean of ANDEFTR. + +**Type:** 32-bit unsigned integer. + +**Unit:** 65536 bits. + +**Valid values:** 0...4294967295 ((0 to $(2^{32}-1)$ ) x $2^{16}$ bits). + +**Reference:** Clause 11.4.1.1.24 of [ITU-T G.9701]. + +## **7.9 Data path performance monitoring objects** + +No data path performance monitoring objects are defined. + +## 7.10 Line test, diagnostics and status objects + +### 7.10.1 Profile + +#### 7.10.1.1 ITU-T G.9701 profile (PROFILE) + +**Description:** Reports for each profile whether operation according to that profile is enabled or disabled. Only one profile can be enabled. + +**Type:** Array of PROFILEdescriptor[0...N-1] with N=5. + +##### PROFILEdescriptor: + +**Type:** boolean. + +**Valid values:** 0 (disabled) and 1 (enabled). + +##### Bit representation + +- 0 [ITU-T G.9701] profile 106a +- 1 [ITU-T G.9701] profile 106b +- 2 [ITU-T G.9701] profile 212a +- 3 [ITU-T G.9701] profile 106c +- 4 [ITU-T G.9701] profile 212c + +**Reference:** Clause 6 of [ITU-T G.9701]. + +### 7.10.2 Initialization + +#### 7.10.2.1 Initialization success/failure cause (INTSFCAUSE) + +**Description:** Reports whether the last full or fast initialization procedure was successful. If the last initialization procedure was not successful, this parameter provides the reason. + +**Type:** enumeration. + +**Valid values:** 0...6 + +- 0 Successful. +- 1 Configuration error. +This error occurs if the line cannot reach the L0 state due to a mismatch of configuration and FTU capabilities. +- 2 Configuration not feasible on the line. +This error occurs if the line cannot reach the L0 state due to a mismatch of configuration and line and noise characteristics. +- 3 Communication problem. +This error occurs, for example, due to corrupted messages or bad syntax messages or if no common mode can be selected in the ITU-T G.994.1 handshaking procedure or due to a timeout. +- 4 No far-end FTU detected. +This error occurs if the far-end FTU is not powered or not connected or if the line is too long to allow detection of a far-end FTU. +- 5 Any other or unknown initialization failure cause. + +**Reference:** Clause 12.3.1 of [ITU-T G.9701]. + +#### 7.10.2.2 Initialization last transmitted downstream signal (INITLASTSIGNALds) + +**Description:** Reports the downstream signal count of the last transmitted initialization signal in the last full or fast initialization performed on the line. The downstream signal count is defined in clause 12.3.1 of [ITU-T G.9701]. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 0...21 + +**Reference:** Clause 12.3.1 of [ITU-T G.9701]. + +#### 7.10.2.3 Initialization last received upstream signal (INITLASTSIGNALus) + +**Description:** Reports the upstream signal count of the last received initialization signal in the last full or fast initialization performed on the line. The upstream signal count is defined in clause 12.3.1 of [ITU-T G.9701]. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 0...10 + +**Reference:** Clause 12.3.1 of [ITU-T G.9701]. + +### 7.10.3 Signal-to-noise ratio margin + +#### 7.10.3.1 Downstream signal-to-noise ratio margin (SNRMds) + +**Description:** Reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the downstream direction during the L0 link state. A first special value (−512) indicates that the signal-to-noise ratio margin is undetermined. A second special value (−511) indicates that the signal-to-noise ratio margin is less than or equal to −51.1 dB. A third special value (+511) indicates that the signal-to-noise ratio margin is greater than or equal to +51.1 dB. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −511, 511 (special values) and −510...+510 (−51.0 dB to +51.0 dB). + +**Reference:** Clauses 9.8.3.2 and 11.4.1.1.10 of [ITU-T G.9701]. + +#### 7.10.3.2 Upstream signal-to-noise ratio margin (SNRMus) + +**Description:** Reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the upstream direction during the L0 link state. The same special values as for SNRMds are defined. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −511, +511 (special value) and −510...+510 (−51.0 dB to +51.0 dB). + +**Reference:** Clauses 9.8.3.2 and 11.4.1.1.10 of [ITU-T G.9701]. + +### 7.10.4 Upstream power back-off + +#### 7.10.4.1 FTU-O estimated upstream power back-off electrical length (UPBOKLE) + +**Description:** Reports the electrical length that would have been sent from the FTU-O to the FTU-R if the electrical length was not forced by the DPU-MIB. If the electrical length is not forced by the DPU-MIB, then this object reports the final electrical length, as determined by the FTU-O (see clause 7.3.1.4.2.1 of [ITU-T G.9701]) and conveyed in the O-UPDATE initialization message (see clause 12.3.3.2.4 of [ITU-T G.9701]). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...1280 (0 dB to 128 dB). + +**Reference:** Clauses 7.3.1.4.2.1 and 12.3.3.2.3 of [ITU-T G.9701]. + +#### **7.10.4.2 FTU-R estimated upstream power back-off electrical length (UPBOKLE-R)** + +**Description:** Reports the estimate of the electrical length, as determined by the FTU-R (see clause 7.3.1.4.2.1 of [ITU-T G.9701]) and conveyed in the R-MSG1 initialization message (see clause 12.3.3.2.3 of [ITU-T G.9701]). + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...1280 (0 dB to 128 dB). + +**Reference:** See clauses 7.3.1.4.2.1 and 12.3.3.2.3 of [ITU-T G.9701]. + +### **7.10.5 Actual aggregate transmit power** + +#### **7.10.5.1 Downstream actual aggregate transmit power (ACTATPds)** + +**Description:** Reports the total amount of transmit power delivered by the FTU-O at the U-O2 reference point, at the instant of measurement. A first special value (−512) indicates that the transmit power is undetermined. A second special value (−311) indicates that the transmit power is less than or equal to −31.1 dBm. A third special value (+311) indicates that the transmit power is greater than or equal to +31.1 dBm. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −311, 311 (special values) and −310...310 (−31 dBm to +31 dBm). + +**Reference:** Clause 11.4.1.2.6 of [ITU-T G.9701]. + +#### **7.10.5.2 Upstream actual aggregate transmit power (ACTATPus)** + +**Description:** Reports the total amount of transmit power delivered by the FTU-R at the U-R2 reference point, at the instant of measurement. The same special values as for ACTATPds are defined. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −311, 311 (special values) and −310...310 (−31 dBm to +31 dBm). + +**Reference:** Clause 11.4.1.2.6 of [ITU-T G.9701]. + +### **7.10.6 Actual transmit PSD per sub-carrier** + +#### **7.10.6.1 Downstream actual transmit PSD per sub-carrier (ACTPSDpsds)** + +**Description:** Reports the transmit PSD per sub-carrier delivered by the FTU-O at the U-O2 reference point as calculated by the VCE from the downstream ACTPSDREF-ps. A special value indicates that no transmit PSD value is available for the sub-carrier, or its transmit power is zero, or is out of the range to be represented. + +**Type:** Array of PSDdescriptor[0...N−1], with N = index of highest supported downstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]). + +##### **PSDdescriptor:** + +**Type:** 8-bit unsigned integer. + +**Unit:** -0.5 dBm/Hz. + +**Valid values:** 0...254 (0 to -127 dBm/Hz) and 255 (special value). + +**Reference:** Clause 11.4.1.2.5 of [ITU-T G.9701]. + +#### **7.10.6.2 Upstream actual transmit PSD per sub-carrier (ACTPSDpsus)** + +**Description:** Reports the transmit PSD per sub-carrier delivered by the FTU-R at the U-R2 reference point, as calculated by the VCE from the upstream ACTPSDREF-ps. A special value indicates that no transmit PSD value is available for the sub-carrier, or its transmit power is zero, or is out of the range to be represented. + +**Type:** Array of PSDdescriptor[0...N-1], with N = index of highest supported upstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]). + +**PSDdescriptor:** See ACTPSDpsds in clause 7.10.6.1. + +**Reference:** Clause 11.4.1.2.5 of [ITU-T G.9701]. + +### **7.10.7 Channel characteristics function per sub-carrier (HLOG)** + +#### **7.10.7.1 Downstream HLOG measurement time (HLOGMTds)** + +**Description:** Reports the number of symbols used to measure the downstream Hlog(f) values. The object is updated only in L0 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...65535 + +**Reference:** Clause 11.4.1.2.1 of [ITU-T G.9701]. + +#### **7.10.7.2 Downstream HLOG sub-carrier group size (HLOGGds)** + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the downstream Hlog(f) values. The object is updated only in L0 link state. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4, 8 + +**Reference:** Clause 11.4.1.2.1 of [ITU-T G.9701]. + +#### **7.10.7.3 Downstream HLOG(f) (HLOGpsds)** + +**Description:** Reports the downstream Hlog(f) as one value per sub-carrier group. A first special value (1023) indicates that the Hlog(f) for this sub-carrier group is undetermined. A second special value (1022) indicates that no measurement could be done for this sub-carrier group because it is out of the MEDLEY set. A third special value (0) indicates that the Hlog(f) for this sub-carrier group is greater than or equal to +6.0 dB. A fourth special value (1020) indicates that the Hlog(f) for this sub-carrier group is less than or equal to -96.0 dB. The object is updated only in L0 link state. + +**Type:** Array of HLOGdescriptor[0...N-1], where N = index of highest sub-carrier index in the MEDLEY set, divided by HLOGG, rounded to the higher integer. + +##### **HLOGdescriptor:** + +**Type:** 16-bit unsigned integer. + +**Unit:** –0.1 dB. + +**Offset:** 6 dB. + +**Valid values:** 1...1019 (+5.9 to –95.9 dB) and 0,1020,1022,1023 (special values). + +**Reference:** Clause 11.4.1.2.1 of [ITU-T G.9701]. + +#### **7.10.7.4 Upstream HLOG measurement time (HLOGMTus)** + +**Description:** Reports the number of symbols used to measure the upstream Hlog(f) values. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...65535 + +**Reference:** Clause 11.4.1.2.1 of [ITU-T G.9701]. + +#### **7.10.7.5 Upstream HLOG sub-carrier group size (HLOGGus)** + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the upstream Hlog(f) values. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4 and 8 + +**Reference:** Clause 11.4.1.2.1 of [ITU-T G.9701]. + +#### **7.10.7.6 Upstream HLOG(f) (HLOGpsus)** + +**Description:** Reports the upstream Hlog(f) as one value per sub-carrier group. The same special values as for the HLOGpsds are defined. The object is updated only in L0 link state. + +**Type:** Array of HLOGdescriptor[0...N–1], where N = index of highest sub-carrier index in the MEDLEY set, divided by HLOGG, rounded to the higher integer. + +##### **HLOGdescriptor:** + +**Type:** 16-bit unsigned integer. + +**Unit:** –0.1 dB. + +**Offset:** 6 dB. + +**Valid values:** 1...1019 (+5.9 to –95.9 dB) and 0,1020,1022,1023 (special values). + +**Reference:** Clause 11.4.1.2.1 of [ITU-T G.9701]. + +### **7.10.8 Signal-to-noise ratio per sub-carrier (SNR)** + +#### **7.10.8.1 Downstream signal-to-noise ratio PSD measurement time (SNRMTds)** + +**Description:** Reports the number of symbols used to measure the downstream SNR(f) values. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...65535 + +**Reference:** Clause 11.4.1.2.2 of [ITU-T G.9701]. + +#### **7.10.8.2 Downstream SNR(f) sub-carrier group size (SNRGds)** + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the downstream SNR(f) values. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4, 8 + +**Reference:** Clause 11.4.1.2.2 of [ITU-T G.9701]. + +#### 7.10.8.3 Downstream SNR(f) (SNRpsds) + +**Description:** Reports the downstream SNR(f) values. A special value indicates the cases defined in clause 11.4.1.2.2 of [ITU-T G.9701]. + +**Type:** Array of SNRdescriptor[0..N-1], where N = index of highest supported downstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]), divided by SNRGds, rounded to the higher integer. + +##### SNRdescriptor: + +**Type:** 8-bit unsigned integer. + +**Unit:** 0.5 dB. + +**Offset:** -32 dB. + +**Valid values:** 0..254 (-32 to 95 dB) and 255 (special value). + +**Reference:** Clause 11.4.1.2.2 of [ITU-T G.9701]. + +#### 7.10.8.4 Upstream signal-to-noise ratio PSD measurement time (SNRMTus) + +**Description:** Reports the number of symbols used to measure the upstream SNR(f) values. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0..65535 (0 to $2^{16}-1$ symbols). + +**Reference:** Clause 11.4.1.2.2 of [ITU-T G.9701]. + +#### 7.10.8.5 Upstream SNR(f) sub-carrier group size (SNRGus) + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the upstream SNR(f) values. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4, 8 + +**Reference:** Clause 11.4.1.2.2 of [ITU-T G.9701]. + +#### 7.10.8.6 Upstream SNR(f) (SNRpsus) + +**Description:** Reports the upstream SNR(f) values. A special value indicates the cases defined in clause 11.4.1.2.2 of [ITU-T G.9701]. + +**Type:** Array of SNRdescriptor[0..N-1], where N = index of highest supported upstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]), divided by SNRGds, rounded to the higher integer. + +**SNRdescriptor:** See SNRpsds in clause 7.10.8.3. + +**Reference:** Clause 11.4.1.2.2 of [ITU-T G.9701]. + +### 7.10.9 Quiet line noise PSD per sub-carrier (QLN) + +#### 7.10.9.1 Downstream QLN measurement time (QLNMTds) + +**Description:** Reports the number of symbols used to measure the downstream QLN(f) values. The object is updated only in L0 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...65535 + +**Reference:** Clause 11.4.1.2.3 of [ITU-T G.9701]. + +#### 7.10.9.2 Downstream QLN sub-carrier group size (QLNGds) + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the downstream QLN(f) values. The object is updated only in L0 link state. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4, 8 + +**Reference:** Clause 11.4.1.2.3 of [ITU-T G.9701]. + +#### 7.10.9.3 Downstream QLN(f) (QLNpsds) + +**Description:** Reports the downstream QLN(f) as one value per sub-carrier group. A first special value (255) indicates that the QLN(f) for this sub-carrier group is undetermined. A second special value (254) indicates that no measurement could be done for this sub-carrier group because it is out of the downstream MEDLEY set. A third special value (0) indicates that the QLN(f) for this sub-carrier group is greater than or equal to $-35\text{ dBm/Hz}$ . A fourth special value (251) indicates that the QLN(f) for this sub-carrier group is less than or equal to $-160.5\text{ dBm/Hz}$ . The object is updated only in L0 link state. + +**Type:** Array of QLNdescriptor[0...N-1], where N = index of highest sub-carrier index in the downstream MEDLEY set, divided by QLNGds, rounded to the higher integer. + +##### QLNdescriptor: + +**Type:** 8-bit unsigned integer. + +**Unit:** $-0.5\text{ dBm/Hz}$ . + +**Offset:** $-35\text{ dBm/Hz}$ . + +**Valid values:** 1..250 ( $-35.5$ to $-160\text{ dBm/Hz}$ ), 0, 251, 254, 255 (special values). + +**Reference:** Clause 11.4.1.2.3 of [ITU-T G.9701]. + +#### 7.10.9.4 Upstream QLN measurement time (QLNMTus) + +**Description:** Reports the number of symbols used to measure the upstream QLN(f) values. The object is updated only in L0 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...65535 + +**Reference:** Clause 11.4.1.2.3 of [ITU-T G.9701]. + +#### 7.10.9.5 Upstream QLN sub-carrier group size (QLNGus) + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the upstream QLN(f) values. The object is updated only in L0 link state. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4 and 8 + +**Reference:** Clause 11.4.1.2.3 of [ITU-T G.9701]. + +#### 7.10.9.6 Upstream QLN(f) (QLNpsus) + +**Description:** Reports the upstream quiet line noise PSD QLN(f) as one value per sub-carrier group. The same special values as for the QLNpsds are defined. The object is updated only in L0 link state. + +**Type:** Array of QLNdescriptor[0...N-1], where N = index of highest sub-carrier index in the upstream MEDLEY set, divided by QLNGus, rounded to the higher integer. + +**QLNdescriptor:** See clause 7.10.9.3 + +**Reference:** Clause 11.4.1.2.3 of [ITU-T G.9701]. + +### 7.10.10 Active line noise PSD per sub-carrier (ALN) + +#### 7.10.10.1 ALN measurement time (ALNMT) + +**Description:** Reports the number of symbols used to measure the ALN(f) values. The object is updated only in L0 link state. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...65535 + +**Reference:** Clause 11.4.1.2.4 of [ITU-T G.9701]. + +#### 7.10.10.2 ALN sub-carrier group size (ALNG) + +**Description:** Reports the number of sub-carriers in any one sub-carrier group used to represent the ALN(f) values. The object is updated only in L0 link state. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 sub-carrier. + +**Valid values:** 1, 2, 4, 8 + +**Reference:** Clause 11.4.1.2.4 of [ITU-T G.9701]. + +#### 7.10.10.3 ALN(f) (ALNps) + +**Description:** Reports the ALN(f). A first special value (255) indicates that the ALN(f) for this sub-carrier is undetermined. A second special value (254) indicates that no measurement could be done for this sub-carrier because it is out of the downstream MEDLEY set. A third special value (0) indicates that the ALN(f) for this sub-carrier is greater than or equal to -35dBm/Hz. A fourth special value (251) indicates that the ALN(f) for this sub-carrier is less than or equal to -160.5 dBm/Hz. The object is updated only in L0 link state. + +**Type:** Array of ALNdescriptor[0...N-1], where N = index of highest sub-carrier index in the downstream MEDLEY set, divided by ALNG, rounded to the higher integer. + +**ALNdescriptor:** + +**Type:** 8-bit unsigned integer. + +**Unit:** -0.5 dBm/Hz. + +**Offset:** -35 dBm/Hz. + +**Valid values:** 1..250 (-35.5 to -160 dBm/Hz), 0, 251, 254 and 255 (special values). + +**Reference:** Clause 11.4.1.2.4 of [ITU-T G.9701]. + +### **7.10.11 Bit allocation per sub-carrier on data symbols** + +#### **7.10.11.1 Downstream bits allocation (BITSpsds)** + +**Description:** Reports the bit allocation values on data symbols in the normal operation interval (NOI) in the downstream direction. + +**Type:** Array of BITSdescriptor[0...N-1], where N = index of highest supported downstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]) plus one. + +##### **BITSdescriptor:** + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 bit. + +**Valid values:** 0..14 + +**Reference:** Clause 10.2.1.4 of [ITU-T G.9701]. + +#### **7.10.11.2 Upstream bits allocation (BITSpsus)** + +**Description:** Reports the bit allocation values on data symbols in the normal operation interval (NOI) in the upstream direction. + +**Type:** Array of BITSdescriptor[0...N-1], where N = index of highest supported upstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]) plus one. + +**BITSdescriptor:** See BITSpsds in clause 7.10.10.1. + +**Reference:** Clause 10.2.1.4 of [ITU-T G.9701]. + +### **7.10.12 Robust Management Channel (RMC)** + +#### **7.10.12.1 Downstream signal-to-noise ratio margin for RMC(SNRM-RMCds)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clause 11.4.1.1.11 of [ITU-T G.9701]) for the RMC in the downstream direction during the L0 link state. A first special value (-512) indicates that the signal-to-noise ratio margin is undetermined. A second special value (-511) indicates that the signal-to-noise ratio margin is less than or equal to -51.1 dB. A third special value (+511) indicates that the signal-to-noise ratio margin is greater than or equal to +51.1 dB. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** -512, -511, +511 (special values) and -510...+510 (-51.0 dB to +51.0 dB). + +**Reference:** Clause 11.4.1.1.11 of [ITU-T G.9701]. + +#### **7.10.12.2 Upstream signal-to-noise ratio margin for RMC(SNRM-RMCus)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clause 11.4.1.1.11 of [ITU-T G.9701]) for the RMC in the upstream direction during the L0 link state. The same special values as for SNRM-RMCds are defined. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** -512, -511, +511 (special values) and -510...+510 (-51.0 dB to +51.0 dB). + +**Reference:** Clause 11.4.1.1.11 of [ITU-T G.9701]. + +#### **7.10.12.3 Downstream bits allocation for RMC(BITS-RMCpsds)** + +**Description:** Reports the bit allocation values on RMC sub-carriers in RMC symbols in the downstream direction. + +**Type:** Array of BITSRMCdescriptor[0...N-1], where N <= 512 + +##### **BITS-RMCdescriptor:** + +**Type:** Record of a sub-carrier index and a bit allocation value. + +###### **Sub-carrier index:** + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0...4095 (sub-carrier index 0 to 4095). + +###### **Bit allocation value:** + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 bit. + +**Valid values:** 0 and 2...6 + +**Reference:** Clause 12.3.4.2.8 of [ITU-T G.9701]. + +#### **7.10.12.4 Upstream bits allocation for RMC(BITS-RMCpsus)** + +**Description:** Reports the bit allocation values on RMC sub-carriers in RMC symbols in the upstream direction. + +**Type:** Array of BITSRMCdescriptor[0...N-1], where N = index of highest supported upstream data-bearing sub-carrier as defined for the enabled profile (see Table 6-1 of [ITU-T G.9701]) plus one. + +**BITSRMCdescriptor:** See BITS-RMCpsds in clause 7.10.12.3. + +**Reference:** Clause 12.3.4.2.7 of [ITU-T G.9701]. + +### **7.10.13 Test parameter time stamps** + +#### **7.10.13.1 Date/time-stamping of near-end test parameter group 1 (STAMP-TEST-NE-G1)** + +**Description:** Reports the date/time when the near-end test parameter group 1 that can change during showtime was last updated. + +**Type:** string (as defined in clause 8.12) + +**Reference:** Clause 11.1 of [ITU-T G.9701]. + +#### **7.10.13.2 Date/time-stamping of far-end test parameter group 1 (STAMP-TEST-FE-G1)** + +**Description:** Reports the date/time when the far-end test parameter group 1 that can change during showtime was last updated. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.1 of [ITU-T G.9701]. + +#### **7.10.13.3 Date/time-stamping of near-end test parameter group 2 (STAMP-TEST-NE-G2)** + +**Description:** Reports the date/time when the near-end test parameter group 2 that can change during showtime was last updated. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.1 of [ITU-T G.9701]. + +#### **7.10.13.4 Date/time-stamping of far-end test parameter group 2 (STAMP-TEST-FE-G2)** + +**Description:** Reports the date/time when the far-end test parameter group 2 that can change during showtime was last updated. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.1 of [ITU-T G.9701]. + +### **7.10.14 On-line reconfiguration (OLR/FRA) time stamps** + +#### **7.10.14.1 Date/time-stamping of last successful downstream bit swap operation (STAMP-BSWds)** + +**Description:** Reports the date/time of the last successful FTU-R initiated bit swap execution that has modified the bits allocation. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.2 Date/time-stamping of last successful upstream bit swap operation (STAMP-BSWus)** + +**Description:** Reports the date/time of the last successful FTU-O initiated bit swap execution that has modified the bits allocation. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.3 Date/time-stamping of last successful downstream autonomous SRA operation (STAMP-SRAdS-)** + +**Description:** Reports the date/time of the last successful FTU-R initiated autonomous SRA execution (excluding SRAs in response to TIGA) that has modified the bits allocation. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.4 Date/time-stamping of last successful upstream autonomous SRA operation (STAMP-SRAus-)** + +**Description:** Reports the date/time of the last successful FTU-O initiated autonomous SRA execution that has modified the bits allocation. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.5 Date/time-stamping of last successful downstream FRA operation (STAMP-FRAdS-)** + +**Description:** Reports the date/time of the last successful FTU-R initiated FRA execution that has modified the bits allocation. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 13.3.1.1 of [ITU-T G.9701]. + +#### **7.10.14.6 Date/time-stamping of last successful upstream FRA operation (STAMP-FRAus-)** + +**Description:** Reports the date/time of the last successful FTU-O initiated FRA execution that has modified the bits allocation. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 13.3.1.1 of [ITU-T G.9701]. + +#### **7.10.14.7 Date/time-stamping of last successful downstream RPA operation (STAMP-RPAds)** + +**Description:** Reports the date/time of the last successful FTU-R initiated RPA execution that has modified the bits allocation for the RMC. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.8 Date/time-stamping of last successful upstream RPA operation (STAMP-RPAus)** + +**Description:** Reports the date/time of the last successful FTU-O initiated RPA execution that has modified the bits allocation for the RMC. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.9 Date/time-stamping of last successful downstream TIGA operation (STAMP-TIGA)** + +**Description:** Reports the date/time of the last successful FTU-O initiated TIGA execution. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Clause 11.2.2.5 of [ITU-T G.9701]. + +#### **7.10.14.10 Date/time-stamping of last successful SREC operation (STAMP-SREC)** + +**Description:** Reports the date/time of the last occurrence of the successful SREC (*success\_srec*) primitive. + +**Type:** string (as defined in clause 8.12). + +**Reference:** Annex R.3 of [ITU-T G.9701]. + +### **7.10.15 Signal attenuation (SATN)** + +#### **7.10.15.1 Downstream signal attenuation (SATNds)** + +**Description:** Reports the downstream SATN. A special value (1023) indicates that the value is undetermined. A second special value (0) indicates that the SATN is less than or equal to 0 dB. A third special value (1001) indicates that the SATN is greater than or equal to 100.1dB. The object is updated only in L0 link state. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** 1...1000 (0.1 dB to +100.0 dB), 0, 1001 and 1023 (special values). + +**Reference:** Clause 11.4.1.2.7.1 of [ITU-T G.9701]. + +#### **7.10.15.2 Upstream signal attenuation (SATNus)** + +**Description:** Reports the upstream SATN. The same special values as for SATNds are defined. The object is updated only in L0 link state. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** 0...1000 (0 dB to +100.0 dB) 0, 1001, 1023 (special values). + +**Reference:** Clause 11.4.1.2.7.2 of [ITU-T G.9701]. + +### **7.10.16 Low power modes** + +#### **7.10.16.1 L2.1 Downstream signal-to-noise ratio margin (L2.1-SNRMds)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the downstream direction during the L2.1N and L2.1B link states. A first special value (−512) indicates that the signal-to-noise ratio margin is undetermined. A second special value (−511) indicates that the signal-to-noise ratio margin is less than or equal to −51.1 dB. A third special value (+511) indicates that the signal-to-noise ratio margin is greater than or equal to +51.1 dB. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −511, +511 (special values) and −510...+510 (−51.0 dB to +51.0 dB). + +**Reference:** Clauses 9.8.3.2 and 11.4.1.1.10 of [ITU-T G.9701]. + +#### **7.10.16.2 L2.1 Upstream signal-to-noise ratio margin (L2.1-SNRMus)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the upstream direction during the L2.1N and L2.1B link states. The same special as for L2.1-SNRMds are defined. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −511, +511 (special values) and −510...+510 (−51.0 dB to +51.0 dB). + +**Reference:** Clauses 9.8.3.2 and 11.4.1.1.10 of [ITU-T G.9701]. + +#### **7.10.16.3 L2.2 Downstream signal-to-noise ratio margin (L2.2-SNRMds)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the downstream direction during the L2.2 link state. A first special value (−512) indicates that the signal-to-noise ratio margin is undetermined. A second special value (−511) indicates that the signal-to-noise ratio margin is less than or equal to −51.1 dB. A third special value (+511) indicates that the signal-to-noise ratio margin is greater than or equal to +51.1 dB. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** −512, −511,+511 (special values) and −510...+510 (−51.0 dB to +51.0 dB). + +**Reference:** Clauses 9.8.3.2 and 11.4.1.1.10 of [ITU-T G.9701]. + +#### **7.10.16.4 L2.2 Upstream signal-to-noise ratio margin (L2.2-SNRMus)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clauses 9.8.3.2 of [ITU-T G.9701] and 11.4.1.1.10 of [ITU-T G.9701]) in the upstream direction during the L2.2 link state. The same special values as for L2.2-SNRMds are defined. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** -512, -511, +511 (special values) and -510...+510 (-51.0 dB to +51.0 dB). + +**Reference:** Clauses 9.8.3.2 and 11.4.1.1.10 of [ITU-T G.9701]. + +#### **7.10.16.5 L2 Downstream signal-to-noise ratio margin for RMC (L2-SNRM-RMCds)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clause 11.4.1.4 of [ITU-T G.9701]) for the RMC in the downstream direction during the L2.1N, L2.1B and L2.2 link state. A first special value (-512) indicates that the signal-to-noise ratio margin is undetermined. A second special value (-511) indicates that the signal-to-noise ratio margin is less than or equal to -51.1 dB. A third special value (+511) indicates that the signal-to-noise ratio margin is greater than or equal to +51.1 dB. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** -512, -511, +511 (special values) and -510...+510 (-51.0 dB to +51.0 dB). + +**Reference:** Clause 11.4.1.1.11 of [ITU-T G.9701]. + +#### **7.10.16.6 L2 Upstream signal-to-noise ratio margin for RMC (L2-SNRM-RMCus)** + +**Description:** Reports the signal-to-noise ratio margin (as defined in clause 11.4.1.4 of [ITU-T G.9701]) for the RMC in the upstream direction during the L2.1N, L2.1B and L2.2 link state. The same special values as for L2-SNRM-RMCds are defined. + +**Type:** 16-bit signed integer. + +**Unit:** 0.1 dB. + +**Valid values:** -512, -511, +511 (special values) and -510...+510 (-51.0 dB to +51.0 dB). + +**Reference:** Clause 11.4.1.1.11 of [ITU-T G.9701]. + +### **7.10.17 Downstream FEXT coupling coefficients (XLOG)** + +#### **7.10.17.1 Downstream XLOG disturber index (XLOGDISTds)** + +**Description:** Reports the VCE\_port\_index of the disturber line to which the XLOGpsds values apply. A special value 0 indicates that the requested VCE\_port\_index (XLOGDREQds) is invalid. + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0 (special value) and 1...65535 + +**Reference:** Clause 11.4.3.2 of [ITU-T G.9701]. + +#### **7.10.17.2 Downstream XLOG bandedges (XLOGBANDSds)** + +**Description:** Defines the set of sub-carriers for which XLOGpsds is reported. For each band in which XLOGpsds is reported, XLOGBANDSds contains a triplet of (start\_subcarrier\_index, stop\_subcarrier\_index, group\_size). The XLOGpsds is reported for all sub-carriers in the band (start and stop subcarrier inclusive) with index equal to start\_subcarrier\_index+m\*group\_size, with m integer. The object is updated only in L0 link state. + +**Type:** Array of XLOGBANDSdescriptor[0...N-1], with 1<=N<= 8 or empty if XLOGDISTds=0 + +##### **XLOGBANDSdescriptor:** + +**Type:** Record of a start sub-carrier index, a stop sub-carrier index and a group size. + +###### **Start sub-carrier index** + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0...4095 (sub-carrier index 0 to 4095). + +###### **Stop sub-carrier index:** + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0...4095 (sub-carrier index 0 to 4095). + +###### **Group size:** + +**Type:** 8-bit unsigned integer. + +**Valid values:** 1, 2, 4, 8, 16, 32, 64 + +**Reference:** Clause 11.4.1.2.9 of [ITU-T G.9701]. + +#### 7.10.17.3 Downstream FEXT coupling (XLOGpsds) + +**Description:** Reports the downstream Xlog(f) as one value per sub-carrier group. A first special value (255) indicates that the Xlog(f) for this sub-carrier group is undetermined. A second special value (254) indicates that no measurement could be done for this sub-carrier group. A third special value (0) indicates that the Xlog(f) for this sub-carrier group is greater than or equal to +40.0 dB. A fourth special value (251) indicates that the Xlog(f) for this sub-carrier group is less than or equal to -85.5 dB. The object is updated only in L0 link state. + +**Type:** Array of XLOGdescriptor[0...N-1], with $1 \leq N \leq 512$ or empty if XLOGDISTds=0. + +##### **XLOGdescriptor:** + +**Type:** 8-bit unsigned integer. + +**Unit:** -0.5 dB. + +**Offset:** 40 dB. + +**Valid values:** 1...250 (39.5 to -85 dB) 0, 251, 254 and 255 (special values). + +**Reference:** Clause 11.4.1.2.8 of [ITU-T G.9701]. + +## 7.11 Channel test, diagnostics and status objects + +### 7.11.1 Actual data rates + +#### 7.11.1.1 Net data rate (NDRds/us) + +**Description:** Reports the NDR as defined in clause 11.4.1.1.1 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the NDR is undetermined. The object is updated only in L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.1 of [ITU-T G.9701]. + +#### 7.11.1.2 Expected throughput (ETRds/us) + +**Description:** Reports the expected throughput as defined in clause 11.4.1.1.3 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the ETR is undetermined. The object is updated only in L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.3 of [ITU-T G.9701]. + +#### 7.11.1.3 Gamma Data Rate (GDRds/us) + +**Description:** Reports the NDR as defined in clause 7.11.1.1, lowered by any throughput capability limitations remaining in the DRA or L2+ functions, assuming no user data is transmitted over all the other lines. A special value ( $2^{32}-1$ ) indicates that the GDR is undetermined. The object is updated only in L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** None. + +### 7.11.2 Attainable data rates + +#### 7.11.2.1 Attainable net data rate (ATTNDRds/us) + +**Description:** Reports the attainable NDR as defined in clause 11.4.1.1.2 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the attainable NDR is undetermined. The object is updated only in L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-1$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.2 of [ITU-T G.9701]. + +#### 7.11.2.2 Attainable expected throughput (ATTETRDs/us) + +**Description:** Reports the attainable expected throughput as defined in clause 11.4.1.1.4 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the attainable expected throughput is undetermined. The object is updated only in L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.4 of [ITU-T G.9701]. + +#### 7.11.2.3 Attainable gamma data rate (ATTGDRds/us) + +**Description:** Reports the attainable NDR (as defined in clause 7.11.2.1), lowered by any throughput capability limitations remaining in the DRA or L2+ functions, assuming no user data is transmitted over all the other Lines, and assuming MAXGDR (as defined in clause 7.2.1.3) is configured to its maximum valid value. A special value ( $2^{32}-1$ ) indicates that the attainable GDR is undetermined. The object is updated only in L0 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** None. + +### 7.11.3 Actual impulse noise protection + +#### 7.11.3.1 Actual INP against SHINE (ACTINPds/us) + +**Description:** Reports the actual INP against SHINE as defined in clause 11.4.1.1.7 of [ITU-T G.9701]. A special value indicates an actual INP against SHINE of 2047 symbols or higher. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...2046 (0 to 2046 symbols) and 2047 (special value). + +**Reference:** Clause 11.4.1.1. 7 of [ITU-T G.9701]. + +#### **7.11.3.2 Actual INP against REIN (ACTINP\_REINds/us)** + +**Description:** Reports the actual INP against REIN as defined in clause 11.4.1.1. 8 of [ITU-T G.9701]. A special value indicates an actual INP against REIN of 63 symbols or higher. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 symbol. + +**Valid values:** 0...62 (0 to 62 symbols) and 63 (special value). + +**Reference:** Clause 11.4.1.1. 8 of [ITU-T G.9701]. + +### **7.11.4 Actual framer settings** + +#### **7.11.4.1 DTU FEC codeword length (DTU-NFECds/us)** + +**Description:** Reports the DTU FEC codeword length as defined in clause 9.3 of [ITU-T G.9701]. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 byte. + +**Valid values:** 32...255 (32 to 255 bytes). + +**Reference:** Clause 9.3 of [ITU-T G.9701]. + +#### **7.11.4.2 DTU FEC redundancy (DTU-RFECds/us)** + +**Description:** Reports the DTU FEC codeword redundancy as defined in clause 9.3 of [ITU-T G.9701]. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 byte. + +**Valid values:** 2, 4, 6, 8, 10, 12, 16 (2, 4, 6, 8, 10, 12, 16 bytes). + +**Reference:** Clause 9.3 of [ITU-T G.9701]. + +#### **7.11.4.3 Number of FEC codewords per DTU (DTU-Qds/us)** + +**Description:** Reports the number of FEC codewords per DTU as defined in clause 9.3 of [ITU-T G.9701]. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 1...16 + +**Reference:** Clause 9.3 of [ITU-T G.9701]. + +### **7.11.5 Test parameters per time interval** + +#### **7.11.5.1 Error-free bits current 15 minutes (EFB-C15Mds/us)** + +**Description:** Reports the number of error-free bits (see clause 11.4.1.1.6 of [ITU-T G.9701]) passed over the alpha reference point at the receiver, divided by 65536, in the current 15 min interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 65536 bits. + +**Valid values:** 0...4294967295 (0 to $2^{16} \times (2^{32} - 1)$ bits). + +**Reference:** Clause 11.4.1.1.6 of [ITU-T G.9701]. + +#### **7.11.5.2 Error-free bits previous 15 minutes (EFB-P15Mds/us)** + +**Description:** Reports the number of error-free bits (see clause 11.4.1.1.6 of [ITU-T G.9701]) passed over the alpha reference point at the receiver, divided by 65536, in the previous 15 min interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 65536 bits. + +**Valid values:** 0...4294967295 (0 to $2^{16} \times (2^{32} - 1)$ bits). + +**Reference:** Clause 11.4.1.1.6 of [ITU-T G.9701]. + +#### **7.11.5.3 Error-free bits current 24 hours (EFB-C24Hds/us)** + +**Description:** Reports the number of error-free bits (see clause 11.4.1.1.6 of [ITU-T G.9701]) passed over the alpha reference point at the receiver, divided by 65536, in the current 24 h interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 65536 bits. + +**Valid values:** 0...4294967295 (0 to $2^{16} \times (2^{32} - 1)$ bits). + +**Reference:** Clause 11.4.1.1.6 of [ITU-T G.9701]. + +#### **7.11.5.4 Error-free bits previous 24 hours (EFB-P24Hds/us)** + +**Description:** Reports the number of error-free bits (see clause 11.4.1.1.6 of [ITU-T G.9701]) passed over the alpha reference point at the receiver, divided by 65536, in the previous 24 h interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 65536 bits. + +**Valid values:** 0...4294967295 (0 to $2^{16} \times (2^{32} - 1)$ bits). + +**Reference:** Clause 11.4.1.1.6 of [ITU-T G.9701]. + +#### **7.11.5.5 Minimum error-free throughput current 15 minutes (MINEFTR-C15Mds/us)** + +**Description:** Reports the minimum error-free throughput (see clause 11.4.1.1.3 of [ITU-T G.9701]) over the current 15 min interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32} - 1$ kbit/s). + +**Reference:** Clause 11.4.1.1.3 of [ITU-T G.9701]. + +#### **7.11.5.6 Minimum error-free throughput previous 15 minutes (MINEFTR-P15Mds/us)** + +**Description:** Reports the minimum error-free throughput (see clause 11.4.1.1.3 of [ITU-T G.9701]) over the previous 15 min interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32} - 1$ kbit/s). + +**Reference:** Clause 11.4.1.1.3 of [ITU-T G.9701]. + +#### 7.11.5.7 Minimum error-free throughput current 24 hours (MINEFTR-C24Hds/us) + +**Description:** Reports the minimum error-free throughput (see clause 11.4.1.1.3 of [ITU-T G.9701]) over the current 24 h interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Reference:** Clause 11.4.1.1.3 of [ITU-T G.9701]. + +#### 7.11.5.8 Minimum error-free throughput previous 24 hours (MINEFTR-P24Hds/us) + +**Description:** Reports the minimum error-free throughput (see clause 11.4.1.1.3 of [ITU-T G.9701]) over the previous 24 h interval. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Reference:** Clause 11.4.1.1.3 of [ITU-T G.9701]. + +### 7.11.6 Low power modes + +#### 7.11.6.1 L2.1 Net data rate (L2.1-NDRds/us) + +**Description:** Reports the NDR in L2.1N and L2.1B link states as defined in clause 11.4.1.1.12 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the NDR is undetermined. The object is updated only in L2.1N and L2.1B link states. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.12 of [ITU-T G.9701]. + +#### 7.11.6.2 L2.2 Net data rate (L2.2-NDRds/us) + +**Description:** Reports the NDR in L2.2 link state as defined in clause 11.4.1.1.13 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the NDR is undetermined. The object is updated only in L2.2 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.13 of [ITU-T G.9701]. + +#### 7.11.6.3 L2.1 Expected throughput (L2.1-ETRds/us) + +**Description:** Reports the expected throughput in L2.1N and L2.1B link state as defined in clause 11.4.1.1.14 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the expected throughput is undetermined. The object is updated only in L2.1N and L2.1B link states. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.14 of [ITU-T G.9701]. + +#### 7.11.6.4 L2.2 Expected throughput (L2.2\_ETRds/us) + +**Description:** Reports the expected throughput in L2.2 link state as defined in clause 11.4.1.1.15 of [ITU-T G.9701]. A special value ( $2^{32}-1$ ) indicates that the expected throughput is undetermined. The object is updated only in L2.2 link state. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967294 (0 to $2^{32}-2$ kbit/s) and 4294967295 ( $2^{32}-1$ special value). + +**Reference:** Clause 11.4.1.1.15 of [ITU-T G.9701]. + +## 7.12 Data path test, diagnostics and status objects + +No data path test, diagnostics and status objects are defined. + +## 7.13 Inventory objects + +## 7.13.1 FTU related inventory + +##### 7.13.1.1 FTU-O ITU-T G.994.1 vendor ID (FTUO\_GHS\_VENDOR) + +**Description:** Reports the FTU-O [ITU-T G.994.1] vendor ID as inserted by the FTU-O in the [ITU-T G.994.1] CL message and as defined in clause 9.3.3.1 of [ITU-T G.994.1]. + +**Type:** string (8 binary octets). + +**Reference:** Clause 9.3.3.1 of [ITU-T G.994.1]. + +##### 7.13.1.2 FTU-R ITU-T G.994.1 vendor ID (FTUR\_GHS\_VENDOR) + +**Description:** Reports the FTU-R [ITU-T G.994.1] vendor ID as inserted by the FTU-R in the [ITU-T G.994.1] CLR message and as defined in clause 9.3.3.1 of [ITU-T G.994.1]. + +**Type:** string (8 binary octets). + +**Reference:** Clause 9.3.3.1 of [ITU-T G.994.1]. + +##### 7.13.1.3 FTU-O version number (FTUO\_VERSION) + +**Description:** Reports the FTU-O version number as inserted by the FTU-O in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]). It is for version control and is vendor specific information. + +**Type:** string (up to 16 binary octets). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +##### 7.13.1.4 FTU-R version number (FTUR\_VERSION) + +**Description:** Reports the FTU-R version number as inserted by the FTU-R in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]). It is for version control. It shall contain the FTU-R firmware version and the FTU-R model. Both shall be encoded in this order and separated by a space character, i.e., "". + +**Type:** string (up to 16 ASCII characters). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +##### 7.13.1.5 FTU-O self-test result (FTUO\_SELFTEST) + +**Description:** Reports the results from the most recent self-test procedure, initiated at power-up (see clause 12.1.2 of [ITU-T G.9701]). The first octet of the self-test result is 00hex if the self-test passed and 01hex if the self-test failed. The interpretation of the other octets is vendor discretionary and can + +be interpreted in combination with the FTU-O [ITU-T G.994.1] vendor ID and DPU system vendor ID. + +**Type:** string (4 binary octets). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +#### **7.13.1.6 FTU-R self-test result (FTUR\_SELFTEST)** + +**Description:** Reports the results from the most recent self-test procedure, initiated either at power-up (see clause 12.1.2 of [ITU-T G.9701]) or by the perform self-test eoc command (see clause 12.2.2.6.1 of [ITU-T G.9701]). The first octet of the self-test result is 00hex if the self-test passed and 01hex if the self-test failed. The interpretation of the other octets is vendor discretionary and can be interpreted in combination with the FTU-R [ITU-T G.994.1] vendor ID and the NT system vendor ID. + +**Type:** string (4 binary octets). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +#### **7.13.1.7 ITU-T G.9701 profile support (FTUO\_PROFILES)** + +**Description:** Reports for each profile whether the FTU-O supports operation according to that profile. + +**Type:** Array of PROFILEdescriptor[0..N-1] with N=5. + +##### **PROFILEdescriptor:** + +**Type:** boolean. + +**Valid values:** false (not supported) and true (supported). + +##### **Bit representation** + +- 0 [ITU-T G.9701] profile 106a. +- 1 [ITU-T G.9701] profile 106b. +- 2 [ITU-T G.9701] profile 212a. +- 3 [ITU-T G.9701] profile 106c. +- 4 [ITU-T G.9701] profile 212c. + +**Reference:** Clause 6 of [ITU-T G.9701]. + +#### **7.13.1.8 ITU-T G.9701 profile support (FTUR\_PROFILES)** + +**Description:** Reports for each profile whether the FTU-R supports operation according to that profile. + +**Type:** Array of PROFILEdescriptor[0..N-1] with N=5. + +##### **PROFILEdescriptor:** + +**Type:** boolean. + +**Valid values:** false (not supported) and true (supported). + +##### **Bit representation** + +- 0 [ITU-T G.9701] profile 106a. +- 1 [ITU-T G.9701] profile 106b. +- 2 [ITU-T G.9701] profile 212a. +- 3 [ITU-T G.9701] profile 106c. +- 4 [ITU-T G.9701] profile 212c. + +**Reference:** Clause 6 of [ITU-T G.9701]. + +#### **7.13.1.9 SREC support (SREC\_SUPPORT\_FTU\_O)** + +**Description:** Indicates whether SREC, specified in Annex R, is supported by the FTU-O. + +**Type:** boolean. + +**Valid values:** false (not supported) and true (supported). + +**Reference:** Annex R of [ITU-T G.9701]. + +#### **7.13.1.10 SREC support (SREC\_SUPPORT\_FTU\_R)** + +**Description:** Indicates whether SREC, specified in Annex R is supported by the FTU-R. + +**Type:** boolean. + +**Valid values:** false (not supported) and true (supported). + +**Reference:** Annex R of [ITU-T G.9701]. + +### **7.13.2 System related inventory** + +#### **7.13.2.1 DPU system vendor ID (DPU\_SYSTEM\_VENDOR)** + +**Description:** Reports the DPU system vendor ID as inserted by the FTU-O in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]) and as defined in clause 9.3.3.1 of [ITU-T G.994.1]. + +**Type:** string (8 binary octets). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +#### **7.13.2.2 NT system vendor ID (NT\_SYSTEM\_VENDOR)** + +**Description:** Reports the NT system vendor ID as inserted by the FTU-R in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]) and as defined in clause 9.3.3.1 of [ITU-T G.994.1]. + +**Type:** string (8 binary octets). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +#### **7.13.2.3 DPU system serial number (DPU\_SYSTEM\_SERIALNR)** + +**Description:** Reports the DPU serial number as inserted by the FTU-O in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]). It is vendor specific information. The combination of DPU system vendor ID and DPU system serial number creates a unique number for each DPU. + +**Type:** string (up to 32 ASCII characters). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +#### **7.13.2.4 NT system serial number (NT\_SYSTEM\_SERIALNR)** + +**Description:** Reports the NT system serial number as inserted by the FTU-R in the embedded operations channel (see clause 11.2.2.10 of [ITU-T G.9701]). It shall contain the NT system serial number, the NT model and the NT firmware version. All shall be encoded in this order and separated by space characters, i.e., "". The combination of NT system vendor ID and NT system serial number creates a unique number for each NT. + +**Type:** string (up to 32 ASCII characters). + +**Reference:** Clause 11.2.2.10 of [ITU-T G.9701]. + +### 7.13.2.5 VCE ID (VCE\_ID) + +**Description:** For the line in a vectored group, the VCE ID uniquely identifies the VCE that manages and controls the vectored group to which the line belongs. It consists of one octet and valid ranges are from 1 to 255. A special value means the line is not in a vectored group. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 0 (special value) and 1..255 + +**Reference:** Clause 11.4.6.1.1 of [ITU-T G.9701]. + +### 7.13.2.6 VCE port index (VCE\_PORT\_INDEX) + +**Description:** For the line in a vectored group, the VCE port index is the physical index that uniquely identifies the VCE port to which the line is connected. It is an integer from 1 to the maximum number of lines supported by the VCE. The combination of VCE ID and VCE port index creates a unique identifier for each vectored FTU-O/-R. + +**Type:** 16-bit unsigned integer. + +**Valid values:** 0 (special value) and 1...65535. + +**Reference:** Clause 11.4.6.1.2 of [ITU-T G.9701]. + +## 7.14 Link State related managed objects + +### 7.14.1 Link State Configuration + +#### 7.14.1.1 Link state forced (LS-FORCED) + +**Description:** Forces the link to transition and to remain in the selected link state. + +**Type:** enumeration + +**Valid values:** 0...4 + +- 0 No link state forced +- 1 L0 link state forced +- 2 L2.1N link state forced +- 3 L2.1B link state forced +- 4 L2.2 link state forced + +**Default value:** 0 (no link state forced) + +**Reference:** Clause 12.1.1.7.1 of [ITU-T G.9701]. + +#### 7.14.1.2 Link state enabling (LS-ENABLE) + +**Description:** Selects the set of allowed low power mode states. + +**Type:** enumeration + +**Valid values:** 0...3 + +- 0 L0 and L3 enabled (L2.1N, L2.1B, L2.2 disabled). +- 1 L0, L3 and L2.1N enabled (L2.1B, L2.2 disabled). +- 2 L0, L3, L2.1N and L2.1B enabled (L2.2 disabled). +- 3 L0, L3, L2.1N, L2.1B and L2.2 enabled. + +**Default value:** 3 (L0, L3, L2.1N, L2.1B and L2.2 enabled) + +**Reference:** Clause 12.1.1.7.2 of [ITU-T G.9701]. + +## **7.14.2 Link State Status Reporting** + +### **7.14.2.1 Link state (LINK-STATE)** + +**Description:** Reports the actual link state + +**Type:** enumeration. + +**Valid values:** 1..5 + +- 1 L0 link state +- 2 L2.1N link state +- 3 L2.1B link state +- 4 L2.2 link state +- 5 L3 link state + +**Reference:** Clause 12.1.1.7.3 of [ITU-T G.9701]. + +### **7.14.2.2 Link state at update of near-end test parameter group 1 (LINK-STATE-TEST-NE-G1)** + +**Description:** Report the link state during which near-end test parameters group 1 were updated. + +**Type:** enumeration. + +**Valid values:** 1...4 + +- 1 L0 link state +- 2 L2.1N link state +- 3 L2.1B link state +- 4 L2.2 link state + +**Reference:** Clause 12.1.1.7.3 of [ITU-T G.9701]. + +### **7.14.2.3 Link state at update of far-end test parameter group 1 (LINK-STATE-TEST-FE-G1)** + +**Description:** Report the link state during which far-end test parameters group 1 were updated. + +**Type:** enumeration. + +**Valid values:** 1...4 + +- 1 L0 link state +- 2 L2.1N link state +- 3 L2.1B link state +- 4 L2.2 link state + +**Reference:** Clause 12.1.1.7.3 of [ITU-T G.9701]. + +## **8 Procedures for performance monitoring functions** + +The functions described in this clause can be performed inside or outside the network element. + +### **8.1 Line transmission states** + +A line can be in one of two transmission states: + +- 1) unavailable state; +- 2) available state. + +The transmission state is determined from SES/non-SES data and the transceiver state SHOWTIME/non-SHOWTIME. The unavailable state is defined in clause 11.4.4.5 of [ITU-T G.9701]. A G.fast line is in the available state when it is not in the unavailable state. + +## 8.2 Threshold reports + +A threshold report (TR) is an unsolicited error performance report from a DPU over its DPU-NB interface with respect to either a 15-minute or 24-hour evaluation period. TRs can only occur when the concerned direction is in the available state. The performance counter thresholds are listed in Table 8-1 and Table 8-2. The TRs related to near-end and far-end ES, SES and UAS are mandatory and other TRs are optional. Threshold reports are not provided at the T/S-interface. + +TR1s shall occur within 10 s after the 15 min threshold is reached or exceeded. + +TR2s shall occur within 10 s after the 24 h threshold is reached or exceeded. + +Entries in Tables 8-1 and 8-2 labelled with names containing the separator "/" represents multiple objects whose names are obtained by considering all combinations of the elements isolated with the separator. For example, the entry labelled with the name A/B\_C/D\_E/F represents eight objects with names A\_C\_E, A\_C\_F, A\_D\_E, A\_D\_F, B\_C\_E, B\_C\_F, B\_D\_E, B\_D\_F. + +**Table 8-1 – Line performance counter thresholds** + +| Category/object | Counter defined in clause: | DPU-NB interface | T/S interface | +|---------------------------------------------------------------------------------------------------------|----------------------------|------------------|---------------| +| Near-end (FTU-O)/far-end (FTU-R) performance monitoring thresholds (15 min/24 h interval) | | | | +| THRESHOLD_NE/FE_15/24_ES | 7.7.8 | R/W (M) | N/A | +| THRESHOLD_NE/FE_15/24_SES | 7.7.9 | R/W (M) | N/A | +| THRESHOLD_NE/FE_15/24_LOSS | 7.7.10 | R/W (O) | N/A | +| THRESHOLD_NE/FE_15/24_LORS | 7.7.11 | R/W (O) | N/A | +| THRESHOLD_NE/FE_15/24_UAS | 7.7.12 | R/W (M) | N/A | +| Initialization performance monitoring thresholds (15 min/24 h interval) | | | | +| THRESHOLD_15/24_FULL_INITS | 7.7.13 | R/W (O) | N/A | +| THRESHOLD_15/24_FAILEDFULL_INITS | 7.7.14 | R/W (O) | N/A | +| THRESHOLD_15/24_FAST_INITS | 7.7.15 | R/W (O) | N/A | +| THRESHOLD_15/24_FAILEDFAST_INITS | 7.7.16 | R/W (O) | N/A | +| Short interruption performance monitoring thresholds (15 min/24 h interval) | | | | +| THRESHOLD_15/24_SPONT_INTRPT | 7.7.19 | R/W (O) | N/A | + +**Table 8-2 – Channel performance monitoring thresholds** + +| Category/object | Counter defined in clause: | DPU-NB interface | T/S interface | +|--------------------------------------------------------------------------------------------------|----------------------------|------------------|---------------| +| Near-end (FTU-O)/far-end (FTU-R) performance monitoring thresholds (15 min/24 h interval) | | | | +| THRESHOLD_NE/FE_15/24_CV | 7.8.4 | R/W (O) | N/A | +| THRESHOLD_NE/FE_15/24_RTXUC | 7.8.6 | R/W (O) | N/A | +| THRESHOLD_NE/FE_15/24_RTXTX | 7.8.7 | R/W (O) | N/A | + +### 8.3 Unavailable and available state filters + +The unavailable state filter is a rectangular sliding window with a default length of 10 s and a 1 s granularity of the slide. The length of the sliding window is configured through the REINIT\_TIME\_THRESHOLD line configuration object (see clauses 7.1.8.7 and 7.1.8.8). + +The available state filter is also a rectangular sliding window with a default length of 10 s and a 1 s granularity of the slide. The length of the sliding window is configured through the REINIT\_TIME\_THRESHOLD line configuration object (see clauses 7.1.8.7 and 7.1.8.8). + +### 8.4 TR1 filter + +The TR1 filter is a 15 min rectangular fixed window. The start and end times for the 15 min rectangular fixed windows shall fall on the hour and at 15, 30 and 45 min after the hour. + +### 8.5 TR2 filter + +The TR2 filter is a 24 h rectangular fixed window. The start and end times for the 24 h rectangular fixed windows shall fall on a 15 min window boundary. + +### 8.6 Evaluation of TR1 + +For second counters, the parameters are counted separately, second by second, over each 15 min rectangular fixed window period. The threshold values shall be programmable over the range 0 to 900 with default value 0. A value of 0 indicates that the threshold is disabled. + +For event counters, the parameters are counted separately, one by one, over each 15 min rectangular fixed window period. The threshold values shall be programmable over the range 0 to the maximum value of the counter with default value 0. A value of 0 indicates that the threshold is disabled. + +A threshold can be crossed at any second within the 15 min rectangular fixed window. As soon as a threshold is crossed, a TR1 as appropriate should be sent on the DPU-NB interface together with a date/time-stamp. Moreover, performance events should continue to be counted to the end of the current 15 min period, at which time the current parameter counts are stored in the history registers and the current parameter registers are reset to zero. + +### 8.7 Evaluation of TR2 + +For second counters, the parameters are counted separately over each 24 h period. The threshold values shall be programmable over the range 0 to 86400 with default value 0. A value of 0 indicates that the threshold is disabled. + +For event counters, the parameters are counted separately over each 24 h period. The threshold values shall be programmable over the range 0 to the maximum value of the counter with default value 0. A value of 0 indicates that the threshold is disabled. + +The DPU shall recognize a 24 h threshold crossing within 15 min of its occurrence. The threshold crossing shall be given the date/time-stamp of the moment of recognition. A TR2 as appropriate should be sent to the NMS with the date/time-stamp. Moreover, performance events should continue to be counted to the end of the current 24 h period, at which time the parameter counts are stored in the history registers and the current parameter registers are reset to zero. + +## **8.8 Threshold report evaluation during transmission state changes** + +Care should be taken to ensure that threshold reports are correctly generated and parameter counters are correctly processed during changes in the transmission state. This implies that all threshold reports should be delayed by the length of the sliding window in the unavailable state filter (see clause 8.3). + +## **8.9 Performance history storage in network elements** + +Performance history storage at the DPU shall consist of the current and previous 15 min and 24 h parameter registers listed in clause 7. Support of performance history storage beyond the current and previous 15 min and 24 h parameter registers listed in clause 7 is not defined. + +It is expected that the PMA at appropriate times pulls parameter register values from the DPU in order to store a performance history beyond the current and previous 15 min and 24 h parameter registers listed in clause 7. + +As a minimum, a measured time and an invalid data flag shall be provided for each stored interval for each direction for each monitored transmission entity. For example, an invalid data flag is set to indicate that the data stored is incomplete or otherwise invalid when: + +- the data has been accumulated over a period of time that is less than the nominal accumulation period duration; +- the data in the current interval is suspect because a terminal is restarted or a register is reset in the middle of an accumulation period; +- the data is incomplete in an accumulation period. For example, an incoming transmission failure or defect may prevent complete collection of far-end performance reports; +- the line is not configured (in which case the PM data and measured time are set to ZERO). + +The invalid data flag is not set as a result of register saturation. + +## **8.10 Register size** + +The register size is 32 bits. When the maximum value of a register is reached, the register shall remain at that maximum value until it is reset, or the value is transferred or discarded, as described in this clause. + +## **8.11 Parameter counts** + +If the DPU-ME does not force the line is into the L3 state, then performance monitoring counters shall be active, irrespective of the actual link state of the line. + +If the DPU-ME forces the line is into the L3 state, then all performance monitoring counters shall be frozen, including the UAS counter. + +All active parameter counts shall be actual (within a tolerance of 1 s) counts for the 15 min and 24 h filtering period. + +The time when the PM counters are frozen shall be excluded from the measured time (see clause 8.9). + +NOTE – The DPU-ME may force the line into the L3 state, e.g., when the line is configured with AdminStatus="down", a SELT measurement is taking place (see G.996.2), or when the RPF PSE is in shutdown (see clause A.7.1.1.2). + +## 8.12 Date/time-stamping of reports + +The date/time-stamping accuracy of reports, together with the method of maintaining the accuracy, is for further study. + +The date/time-stamp is a string of ASCII characters formatted as "\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?" + "(Z|[+\-]\d{2}:\d{2})" (see [b-IETF RFC 6021] and [b-IETF RFC 3339]). + +Equipment clock accuracy requirements are for further study. + +## 8.13 Inhibiting performance monitoring parameters + +The accumulation of certain performance parameters is inhibited during certain periods. Inhibition of performance monitoring parameters is defined in clause 11.4.4.6 of [ITU-T G.9701]. + +## Annex A + +### Physical layer management for reverse power feeding of remote access equipment + +(This annex forms an integral part of this Recommendation.) + +#### A.1 Scope + +This annex specifies the physical layer management for RPF of remote access equipment, e.g., DPUs containing digital subscriber line (DSL) or G.fast transmission systems, consisting of: + +- the RPF operations, administration and maintenance (OAM) protocol between the NT ME (located in the network termination, see Figure 5-1 of [ITU-T G.9701]) and the DPU ME (located in the remote access equipment, like a DPU, see Figure 5-1 of [ITU-T G.9701]) (see clauses A.6.2.1 to A.6.2.4); +- the RPF indications and parameters exchanged between the NT ME and the DPU ME (see clauses A.6.2.1.1 and A.6.2.5, respectively); +- the RPF managed objects applicable at the Northbound interface of the remote access equipment, e.g., a DPU-NB interface towards an PMA (see clause A.7). + +The RPF OAM protocol and the RPF parameters exchanged using the RPF OAM protocol relate to [ETSI TS 101 548]. The RPF OAM protocol consists of RPF OAM messages mapped as information payload on the [ITU-T G.9701] clear embedded operations channel (eoc) (see clause 11.2.2.4 of [ITU-T G.9701]). + +NOTE – The RPF OAM messages defined in this annex may also be mapped as information payload on the [b-ITU-T G.993.2] clear eoc (see clause 11.2.3.8 of [b-ITU-T G.993.2]). + +#### A.2 References + +[ETSI TS 101 548] ETSI Technical Specification 101 548 (2016), *Access, terminals, transmission and multiplexing (ATM); European requirements for reverse powering of remote access equipment*. + +[IETF RFC 3986] IETF RFC 3986 (2005), *Uniform resource identifier (URI): Generic syntax*. + +#### A.3 Definitions + +**A.3.1 broadband bypass:** Broadband bypass refers to the scenario whereby the DPU supports "Reverse Power Feed Architecture – No POTS with Broadband Bypass" (RPFA NOP-BB) as defined in clause 5.8 of [ETSI TS 101 548]. Or, alternatively, the scenario whereby the DPU supports Zero Touch-Remote Copper Reconfiguration defined in clause 7.4 of [ETSI TS 101 548] whereby exchange POTS is not present on the line, but where there is an overlay DSL service (i.e., "naked" or "dry" DSL). + +**A.3.2 bypass mode:** Operational state of the POTS adapters or power splitter where there is a metallic connection to the exchange or to an ATA. And, specifically for RPFA-NOP-BB architecture option, the operational state of the stateless Switching Function (SF), whereby the non-ITU-T G.9701 xTU-R of the CPE is connected to an xTU-O of the CO/cabinet. + +**A.3.3 normal mode:** Operational state of the POTS adapters or power splitter where there is no metallic connection to the exchange or to an ATA. And, specifically for RPFA-NOP-BB architecture option, the operational state of the stateless Switching Function (SF), whereby the FTU-R of the CPE is connected to the FTU-O of the DPU. + +**A.3.4 POTS remote copper reconfiguration (RCR):** POTS RCR refers to the Scenario where POTS from the exchange may be provided to the subscriber and shall be disconnected by the DPU, prior to start-up of the DPU. Refer to clause 6.2.5.1 "PRP definition" of [ETSI TS 101 548]. + +#### **A.4 Abbreviations and acronyms** + +| | | +|--------|-----------------------------------------------------------------------------------| +| ACM | AC Mains | +| ATA | Analogue Telephone Adapter | +| BBA | Battery Backup Available | +| CPF | Common Power Feed | +| DGL | Dying Gasp Loss | +| IAR | International Amateur Radio | +| IFN | Intensity of current Feed Now | +| LLPF | Last reverse power feeding line Loss of Power Failure | +| NTE | Network Termination Equipment | +| OAM | Operations, Administration and Maintenance | +| OHP | Off-Hook Phone | +| PC | Power Class | +| PE | Power Extractor | +| POTS | Plain Old Telephony Service | +| PRP PS | Plain old telephony service Remote copper reconfiguration Protocol Power Splitter | +| PRP | POTS RCR Protocol | +| PSE | Power Source Equipment | +| RCR | Remote Copper Reconfiguration | +| RCS | ReConfiguration State | +| RPF | Reverse Power Feeding | +| VoIP | Voice over Internet Protocol | + +#### **A.5 DPU and NT management architecture** + +This annex extends the reference model of DPU and NT management for the management of RPF. See Figure A.1. On the FTU-O side, the DPU ME manages the power extractor (PE) and remotely manages the PSE. On the FTU-R side, the NT ME manages the power source equipment (PSE). In order to manage the PSE from the DPU-ME, two communication channels are used: + +- 1) a bidirectional channel using the clear eoc between the DPU ME and NT ME. This channel transports the RPF OAM messages; +- 2) a low latency unidirectional channel using indicator bits over the RMC from the FTU-R to the FTU-O side. This channel transports PSE indications that are time sensitive. + +![Figure A.1 – Reference model of DPU and NT management with RPF. The diagram shows two main components connected by a 'Copper pair' labeled 'U-O' and 'U-R'. On the left, the 'DPU' (Data Processing Unit) contains a 'PHY', 'L2+', 'FTU-O-1', 'DPU ME', and 'PE-1'. The 'FTU-O-1' is connected to the 'L2+' and 'DPU ME'. The 'DPU ME' is connected to the 'PE-1' and the 'FTU-O-1'. The 'FTU-O-1' is also connected to the 'Copper pair'. On the right, the 'NT' (Network Termination) contains a 'PHY', 'L2+', 'FTU-R-1', 'NT ME', and 'PSE'. The 'FTU-R-1' is connected to the 'L2+' and 'NT ME'. The 'NT ME' is connected to the 'PSE' and the 'FTU-R-1'. The 'FTU-R-1' is also connected to the 'Copper pair'. Between the 'FTU-O-1' and 'DPU ME', and between the 'FTU-R-1' and 'NT ME', there are bidirectional arrows labeled 'RPF OAM (clear eoc)' and 'PSE indications'. The diagram is labeled 'G.997.2(19)_FA.1' at the bottom right.](ec96d99a16edb981eb7defe41a79b57f_img.jpg) + +Figure A.1 – Reference model of DPU and NT management with RPF. The diagram shows two main components connected by a 'Copper pair' labeled 'U-O' and 'U-R'. On the left, the 'DPU' (Data Processing Unit) contains a 'PHY', 'L2+', 'FTU-O-1', 'DPU ME', and 'PE-1'. The 'FTU-O-1' is connected to the 'L2+' and 'DPU ME'. The 'DPU ME' is connected to the 'PE-1' and the 'FTU-O-1'. The 'FTU-O-1' is also connected to the 'Copper pair'. On the right, the 'NT' (Network Termination) contains a 'PHY', 'L2+', 'FTU-R-1', 'NT ME', and 'PSE'. The 'FTU-R-1' is connected to the 'L2+' and 'NT ME'. The 'NT ME' is connected to the 'PSE' and the 'FTU-R-1'. The 'FTU-R-1' is also connected to the 'Copper pair'. Between the 'FTU-O-1' and 'DPU ME', and between the 'FTU-R-1' and 'NT ME', there are bidirectional arrows labeled 'RPF OAM (clear eoc)' and 'PSE indications'. The diagram is labeled 'G.997.2(19)\_FA.1' at the bottom right. + +**Figure A.1 – Reference model of DPU and NT management with RPF** + +## A.6 Network management protocol + +### A.6.1 DPU Northbound management protocol + +This Annex makes no presumption about which management protocol is used between the PMA and the DPU for transport of the RPF-managed objects defined in clause A.7. + +### A.6.2 RPF OAM management protocol + +#### A.6.2.1 RPF OAM message structure + +The structure of the RPF OAM message is shown in Table A.1. The message contains five fields. Each RPF OAM message shall be mapped on the information payload of the clear eoc of clause 11.2.2.4 of [ITU-T G.9701]. + +NOTE – The RPF OAM messages may also be mapped as information payload on the [b-ITU-T G.993.2] clear eoc (see clause 11.2.3.8 of [b-ITU-T G.993.2]). + +**Table A.1 – RPF OAM message structure** + +| Octet number | Length (octets) | Description | +|--------------|-----------------|------------------------------------| +| 1-2 | 2 | Type (1548 16 for RPF) | +| 3 | 1 | Subtype (03 16 for OAM) | +| 4-5 | 2 | Flags (see clause A.6.2.1.1) | +| 6 | 1 | Code (see clause A.6.2.1.2) | +| 7-48 | 0-42 | Data (see clause A.6.2.2) | + +#### A.6.2.1.1 RPF OAM flags field + +The flags field of the RPF OAM message as sent by the DPU ME to the NT ME is defined in Table A.2. The flags field shall be sent by the DPU ME as part of an RPF OAM parameter request message (see clause A.6.2.4). + +**Table A.2 – RPF OAM flags field as sent by the DPU ME** + +| Bit(s) | Name | Description | +|--------|---------------------------|-------------------------------------| +| 15-0 | Reserved for use by ITU-T | Reserved bits shall be set to zero. | + +The flags field of the RPF OAM message as sent by the NT ME to the DPU ME is defined in Table A.3. The flags field shall be sent by the NT ME as part of an RPF OAM event notification message (see clause A.6.2.2) and as part of an RPF OAM parameter response message (see clause A.6.2.4). + +NOTE – The RPF OAM flag fields in Table A.3 are consistent with the indications defined in clause 6.3 of [ETSI TS 101 548]. Alternatively, the PSE may send these indications to the PE using the means defined in clause 6.3 of [ETSI TS 101 548]. + +**Table A.3 – RPF OAM flags field as sent by the NT ME** + +| Bit(s) | Name | Description | +|--------|---------------------------|----------------------------------------------------------------------------------------------------------------------------------| +| 15-5 | Reserved for use by ITU-T | Reserved bits shall be set to zero. | +| 4 | PSE-DGL (dying gasp loss) | Set to ONE for indication of a PSE lost power dying gasp (see Note).
Set to ZERO otherwise. | +| 3 | PSE-OHP (off-hook phone) | Set to ONE for indication of a PSE Power Fail with off-hook phone during NORMAL OPERATIONS (see Note).
Set to ZERO otherwise. | +| 2 | PSE-BAT | Set to ONE for indication of a PSE operation on a battery.
Set to ZERO otherwise. | +| 1 | PSE-ACM (AC mains) | Set to ONE for indication of a PSE operation on mains power with no battery backup (BBA) available.
Set to ZERO otherwise. | +| 0 | PSE-BBA | Set to ONE for indication of a PSE operating on mains power with BBA.
Set to ZERO otherwise. | + +NOTE – When this indication occurs, the NT could lose power before the RPF OAM message has been sent. This indication may be sent through the RPF OAM message. This indication shall be sent through the power-related far-end primitive defined in clause 11.3.3.2 of [ITU-T G.9701]. + +#### A.6.2.1.2 RPF OAM code field + +The code field of the RPF OAM message is defined in Table A.4. This field identifies the message code. + +**Table A.4 – RPF OAM code field** + +| Code | Description | Comment | Source | +|------------------------------------|---------------------------|----------------------------------------------|--------| +| 00 16 | Reserved for use by ITU-T | | | +| 01 16 | Event notification | Alerts the DPU of RPF events | NT ME | +| 02 16 | Parameter request | Requests one or more specific RPF parameters | DPU ME | +| 03 16 | Parameter response | Returns one or more specific RPF parameters | NT ME | +| 03 16 -FF 16 | Reserved for use by ITU-T | | | + +#### A.6.2.2 RPF OAM event notification message + +The RPF OAM event notification message is defined in Table A.5. + +**Table A.5 – RPF OAM event notification message** + +| Octets | Description | +|--------|------------------------------------------------| +| 2 | Type (1548 16 for RPF) | +| 1 | Subtype (03 16 for OAM) | +| 2 | Flags (see clause A.6.2.1.1) | +| 1 | Code (01 16 for event notification) | +| 0-42 | Data (see Note) | + +NOTE – For this version of the RPF OAM protocol, the transmitter shall not send any data octets. For compatibility with future definition of data octets, the receiver shall ignore all data octets sent by the transmitter. + +**A.6.2.3 RPF OAM parameter request message** + +The RPF OAM parameter request message is defined in Table A.6. + +**Table A.6 – RPF OAM parameter request message** + +| Octets | Description | +|--------|--------------------------------------------------------------------------------------------------------------------------------------------| +| 2 | Type (1548 16 for RPF) | +| 1 | Subtype (03 16 for OAM) | +| 2 | Flags (see clause A.6.2.1.1) | +| 1 | Code (02 16 for managed object request) | +| 3-42 | 1 to 14 parameter descriptors. Each descriptor consists of 3 octets (see tables of clause A.7):
– Branch (1 octet)
– Leaf (2 octets) | + +**A.6.2.4 RPF OAM parameter response message** + +The RPF OAM parameter response message is defined in Table A.7. A parameter response message shall be sent by the NT ME within 1 s of receipt of a parameter request message. + +**Table A.7 – RPF OAM parameter response message** + +| Octets | Description | +|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 2 | Type (1548 16 for RPF) | +| 1 | Subtype (03 16 for OAM) | +| 2 | Flags (see clause A.6.2.1.1) | +| 1 | Code (03 16 for managed object response) | +| 5-42 | A nonzero number of parameter containers. Each container is variable length (see tables of clause A.7):
– Branch (1 octet)
– Leaf (2 octets)
– Width (1 octet)
– Value ( width octets) | + +### A.6.2.5 RPF OAM parameters + +The RPF OAM parameters are defined in Table A.8. These parameters are exchanged through RPF OAM parameter request messages (see clause A.6.2.3) and RPF OAM parameter response messages (see clause A.6.2.4). + +NOTE – The RPF OAM parameters in Table A.8 are consistent with clause 6.4 of [ETSI TS 101 548]. + +**Table A.8 – RPF OAM parameters** + +| Name | Branch | Leaf | Width | Definition | +|--------------------------------------------------|------------------|--------------------|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Status | | | | | +| RPF-IFN
(intensity
of current
feed now) | 04 16 | 0001 16 | 02 16 | Average current feed now at the UR-2P reference point, expressed in milliamperes, and represented as a 16 bit unsigned integer with valid values 0 to 400 mA. The averaging time window and accuracy are defined in [ETSI TS 101 548]. | +| Diagnostics | | | | | +| PSE-SUF | 05 16 | 0001 16 | 01 16 | Latest PSE Start-Up Failure indication, detected during "Start-Up". The octet is formatted as a bitmap, with a bit set to ONE if and only if the corresponding failure is detected. The bits are defined as follows (bit 0 lsb to bit 7 msb):
bit 0: ELC-0 (Open tip-to-ring);
bit 1: ELC-1 (Short tip-to-ring);
bit 2: ELC-2 (POTS Exchange (foreign) DC voltage)
bit 3: ELC-3 (Off-hook phone);
bit 4: Mismatch of the PSE RPF Class with the DPU RPF Class;
bit 5: Unknown;
bit 6: Set to ZERO, reserved for use by the ITU-T;
bit 7: Set to ZERO, reserved for use by the ITU-T.
No more than 1 bit shall be set to ONE in the field. | +| PSE-SDC | 05 16 | 0002 16 | 01 16 | Latest PSE Shutdown Cause indication, detected during "Normal Operation". The octet is formatted as a bitmap, with a bit set to ONE if and only if the corresponding cause applies. The bits are defined as follows (bit 0 lsb to bit 7 msb):
bit 0: ELC-0 (Open tip-to-ring);
bit 1: ELC-1 (Short tip-to-ring);
bit 2: ELC-3 (Off-hook phone);
bit 3: Overload time violation (Note 1);
bit 4: Maintain power signature violation (Note 2);
bit 5: Unknown;
bit 6: Set to ZERO, reserved for use by the ITU-T;
bit 7: Set to ZERO, reserved for use by the ITU-T.
No more than 1 bit shall be set to ONE in the field. | +| PSE-IE | 05 16 | 0003 16 | 02 16 | Injected energy by the PSE at U-R2P reference point, while PSE is in the "Normal Operations" state, expressed in units of mWh and represented as a 16-bit unsigned integer. Valid values range from 0mWh to 65535 mWh. The value shall wrap on overflow. The accuracy is defined in [ETSI TS 101 548] (Note 3). | + +**Table A.8 – RPF OAM parameters** + +| Name | Branch | Leaf | Width | Definition | +|----------------------------------------------------------------------------------------------------------------------|------------------|--------------------|------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Inventory | | | | | +| NTE-CPF (network termination equipment - common power feed) | 06 16 | 0001 16 | 01 16 | 00 16 : PSE in physical entity separate from NT (not integrated).
01 16 : PSE in same physical entity with NT (integrated).
Other values are reserved for use by ITU-T. | +| PSE-PC (power class) | 06 16 | 0002 16 | 01 16 | 01 16 : Actual PSE-PC is SR1.
02 16 : Actual PSE-PC is SR2.
03 16 : Actual PSE-PC is SR3.
Other values are reserved for use by ITU-T. | +| PSE-PRP | 06 16 | 0002 16 | 01 16 | 00 16 : PRP not supported;
01 16 : PRP supported;
Other values are reserved for use by ITU-T. | +| NOTE 1 – Overload time is defined in Table 35 of [ETSI TS 101 548]. | | | | | +| NOTE 2 – Maintain power signature is defined in Table 37 of [ETSI TS 101 548]. | | | | | +| NOTE 3 – The parameter PSE-IE is read by the DPU periodically to construct current and previous 15 min DPU counters. | | | | | + +#### A.7 DPU Northbound managed objects + +The list of managed objects contains six types of information: + +- 1) configuration objects (see Table A.9); +- 2) fault monitoring – failures (alarm indications) (see Table A.10); +- 3) fault monitoring – threshold crossing (alert messages); +- 4) performance monitoring objects (counters) (see Table A.11); +- 5) test, diagnostic and status objects (see Tables A.12 and A.13); +- 6) inventory objects (see Table A.14). + +**Table A.9 – RPF configuration objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|-------------------------------------------------------------|--------------------|------------------| +| Per line near-end (DPU) configuration objects | | | +| Power extraction when PSE on battery (PE-PEB) | A.7.1.1.1 | R/W (M) | +| Service when PSE shutdown (FTU-SRV) | A.7.1.1.2 | R/W (M) | +| Forced ReConfiguration state (DPU-FRCS) | A.7.1.1.3 | R/W (M) | +| Conditional Forced ReConfiguration state (DPU-CFRCS) | A.7.1.1.4 | R/W (M) | +| Conditional Forced ReConfiguration state time (DPU-CFRCST) | A.7.1.1.5 | R/W (M) | +| Power extraction (PE-PWR) | A.7.1.1.6 | R/W (M) | +| Per line far-end (PSE) configuration objects | | | +| | | | +| Common near-end (DPU) configuration objects | | | +| | | | + +**Table A.10 – RPF failures and alarms** + +| Category/object | Defined in clause: | DPU-NB interface | +|-----------------------------------------------------------|--------------------|------------------| +| Per line near-end (DPU) failures and alarms | | | +| Loss of power alarm – unknown reason (PE-UKN) | A.7.2.1.1 | R (M) | +| ReConfiguration State Change alarm (DPU-RCSC) | A.7.2.1.2 | R (M) | +| PRP Error Status alarm (DPU-PRP-ERROR) | A.7.2.1.3 | R (M) | +| Line Error Status alarm (DPU-LES) | A.7.2.1.4 | R (O) | +| Per line far-end (PSE) failures and alarms | | | +| Loss of power alarm – off-hook phone (PSE-OHP) | A.7.2.2.1 | R (M) | +| Loss of power alarm – PSE lost input power (PSE-DLG) | A.7.2.2.2 | R (M) | +| Common near-end (DPU) failures and alarms | | | +| Loss of power failure – fault condition (DPU-LLPF) | A.7.2.3.1 | R (M) | +| Loss of power failure – insufficient power (DPU-MLPF) | A.7.2.3.2 | R (M) | +| Loss of power alarm – normal shutdown (DPU-LLPS) | A.7.2.3.3 | R (M) | + +**Table A.11 – RPF performance monitoring objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|---------------------------------------------------------------------------------------------------------------|--------------------|------------------| +| Per line near-end (DPU) performance monitoring counters (current/previous 15 min/24 h interval) | | | +| Measured Time (CURR/PREV_NE/FE_15_L_TIME) | A.7.3.1 | R (O) | +| Invalid Data flag (PREV_NE/FE_15_L_INVALID) | A.7.3.2 | R (O) | +| Time Stamp (PREV_NE/FE_15_L_STAMP) | A.7.3.3 | R (O) | +| DPU Extracted Energy counter (CURR/PREV_NE_15_EE) | A.7.3.4 | R (O) | +| Per line far-end (PSE) performance monitoring counters (current/previous 15 min/24 h interval) | | | +| Measured Time (CURR/PREV_NE/FE_15_L_TIME) | A.7.3.1 | R (O) | +| Invalid Data flag (PREV_NE/FE_15_L_INVALID) | A.7.3.2 | R (O) | +| Time Stamp (PREV_NE/FE_15_L_STAMP) | A.7.3.3 | R (O) | +| PSE Injected Energy counter (CURR/PREV_FE_15_IE) | A.7.3.5 | R (O) | +| Common near-end (DPU) performance monitoring counters (current/previous 15 min/24 h interval) | | | +| | | | + +**Table A.12 – RPF status objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|------------------------------------------------------|--------------------|------------------| +| Per line near-end (DPU) status objects | | | +| Actual power class (PE-PC) | A.7.4.1.1 | R (M) | +| Reverse power feeding state (PE-RPF) | A.7.4.1.2 | R (M) | +| ReConfiguration State (DPU-RCS) | A.7.4.1.3 | R (M) | +| PRP Error Status (DPU-PRP-ERROR) | A.7.4.1.4 | R (M) | +| Line Error Status (DPU-LES) | A.7.4.1.5 | R (M) | + +**Table A.12 – RPF status objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------|--------------------|------------------| +| Per line far-end (PSE) status objects | | | +| Actual power class (PSE-PC) | A.7.4.2.1 | R (M) | +| Reverse power feeding state (PSE-RPF) | A.7.4.2.2 | R (M) | +| Common near-end (DPU) status objects | | | +| | | | + +**Table A.13 – RPF diagnostics objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|----------------------------------------------------|--------------------|------------------| +| Per line near-end (DPU) diagnostics objects | | | +| | | | +| Per line far-end (PSE) diagnostics objects | | | +| Latest PSE Start-Up Failure cause (PSE-SUF) | A.7.5.2.1 | R (M) | +| Latest PSE ShutDown Cause (PSE-SDC) | A.7.5.2.2 | R (M) | +| Common near-end (DPU) diagnostics objects | | | +| | | | + +**Table A.14 – RPF inventory objects** + +| Category/object | Defined in clause: | DPU-NB interface | +|--------------------------------------------------|--------------------|------------------| +| Per line near-end (DPU) inventory objects | | | +| ReConfiguration Capability (DPU-RC) | A.7.6.1.1 | R (M) | +| Per line far-end (PSE) inventory objects | | | +| Integrated into NTE (NTE-CPF) | A.7.6.2.1 | R (M) | +| Battery backup available (PSE-BBA) | A.7.6.2.2 | R (M) | +| PRP Capability (PSE-PRP) | A.7.6.2.3 | R (M) | +| Common near-end (DPU) inventory objects | | | +| | | | + +## A.7.1 RPF configuration objects + +### A.7.1.1 Per line near-end (DPU) configuration objects + +#### A.7.1.1.1 Power extraction when PSE is on battery (PE-PEB) + +**Description:** Defines whether for the line, the PE is allowed to extract power from the line when the PSE-RPF is operating on battery power (see clause A.7.4.2.2) and sufficient power is available from one or more remaining RPF lines for normal operation of the DPU. + +**Type:** boolean. + +**Valid values:** false [only minimal power extraction, compliant with the maintain power signature current (see clause 7.5.2.2 of [ETSI TS 101 548]), allowed], true (power extraction allowed). + +**Default value:** false (only minimal power extraction, compliant with the maintain power signature current, allowed). + +**Reference:** Section 8.1 (R-22) of [b-BBF TR-301], clause 7.5.2.2 of [ETSI TS 101 548]. + +#### **A.7.1.1.2 Service when PSE shuts down (FTU-SRV)** + +**Description:** Defines for the line, the FTU/L2+ action when the PSE is in shutdown (PSE-RPF, see clause A.7.4.2.2). Values NL0, ESO and SRV are conditional on there being sufficient power from one or more remaining RPF lines available for normal operation of the DPU. If this condition is not met, value FL3 is applied instead. + +**Type:** Enumeration. + +**Valid values:** 0...3: + +- 0 FL3: Force the line to the L3 link state (no service). +- 1 NL0: Force the line to an enabled low power link state (limited service). +- 2 ESO: Force the line to support emergency services only (all link states allowed). +- 3 SRV: No service limitations forced on the line (all link states allowed). + +**Default value:** 0 (FL3 – no service). + +**Reference:** Section 8.1 (R-26) of [b-BBF TR-301]. + +#### **A.7.1.1.3 Forced ReConfiguration state (DPU-FRCS)** + +**Description:** Defines for the line, the Forced ReConfiguration state: either None, Normal or Bypass. + +**Type:** Enumeration. + +**Valid values:** 0...2 + +- 0 None: No Forced ReConfiguration State. The DPU-FRCS configuration object has no effect on the line's ReConfiguration State. +- 1 Normal: The line is forced to enter and maintain Normal mode. +- 2 Bypass: The line is forced to enter and maintain Bypass mode. This command is ignored for a given line if this line is solely reverse powering the DPU or attempting to start-up the DPU. + +**Default value:** 0 (None). + +**Reference:** Clauses 5.8 and 7.4 of [ETSI TS 101 548]. + +#### **A.7.1.1.4 Conditional Forced ReConfiguration State (DPU-CFRCS)** + +**Description:** Defines for the line, the Conditional Forced ReConfiguration State, to be applied upon either enforcing no service on the line (i.e., FTU-SRV value FL3 is applied, see clause A.7.1.1.2) for a time period T (DPU-CFRCS-T, see clause A.7.1.1.5) or upon DPU shutdown. + +**Type:** Enumeration. + +**Valid values:** 0...1 + +- 0 None: No Conditional Forced ReConfiguration State. The line maintains its current ReConfiguration State (see clause A.7.4.1.3). +- 1 Bypass: The line's ReConfiguration State is forced to Bypass mode. + +**Default value:** 0 (None). + +**Reference:** Clauses 5.8 and 7.4 of [ETSI TS 101 548]. + +#### **A.7.1.1.5 Conditional Forced ReConfiguration State Time (DPU-CFR CST)** + +**Description:** Defines the time period T to be used with configuration object DPU-CFRCS (see clause A.7.1.1.4). + +**Type:** 8-bit unsigned integer. + +**Units:** 1 second. + +**Valid values:** 0...255 + +**Default value:** 30 (30 seconds). + +**Reference:** Clause 5.8 of [ETSI TS 101 548]. + +#### **A.7.1.1.6 Power extraction (PE-PWR)** + +**Description:** Defines whether or not power extraction from the line is allowed. + +**Type:** Enumeration. + +**Valid values:** 0...1 + +0       Allowed: The PE may extract power from this line. + +1       Not allowed: The PE should not extract more than 35 mA at U-O interface (excluding start-up transients) unless the given line is solely reverse powering the DPU or attempting to start-up the DPU. + +**Default value:** 0 (Allowed). + +**Reference:** Clause 5.8 of [ETSI TS 101 548]. + +#### **A.7.1.2 Per line far-end (PSE) configuration objects** + +No per-line far-end (PSE) configuration objects are defined. + +#### **A.7.1.3 Common near-end (DPU) configuration objects** + +No common near-end (DPU) configuration objects are defined. + +### **A.7.2 RPF failures and alarms** + +#### **A.7.2.1 Per line near-end (DPU) failures and alarms** + +##### **A.7.2.1.1 Loss of power alarm – unknown reason (PE-UKN)** + +If the PMA has enabled the PE-UKN alarm notification, the DPU shall autonomously send a PE-UKN alarm to the PMA when the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-UKN. + +##### **A.7.2.1.2 Reconfiguration State Change alarm (DPU-RCSC)** + +If the PMA has enabled the DPU-RCSC alarm notification, the DPU shall autonomously send a Reconfiguration State Change (DPU-RCSC) alarm upon a state change of the line's Reconfiguration State (DPU-RCS, see clause A.7.4.1.3). + +##### **A.7.2.1.3 PRP Error Status alarm (DPU-PRP-ERROR)** + +If the PMA has enabled the DPU-PRP-ERROR alarm notification, the DPU shall autonomously send a PRP Error Status (DPU-PRP-ERROR) alarm upon the PRP Error Status (DPU-PRP-ERROR, see clause A.7.4.1.4) indicating an error condition on the line. + +##### **A.7.2.1.4 Line Error Status alarm (DPU-LES)** + +If the PMA has enabled the DPU-LES alarm notification and the DPU supports the Line Error Status object, the DPU shall autonomously send a Line Error Status (DPU-LES) alarm upon the Line Error Status (DPU-LES, see clause A.7.4.1.5) indicating an error condition on the line. + +#### **A.7.2.2 Per line far-end (PSE) failures and alarms** + +##### **A.7.2.2.1 Loss of power alarm – off-hook phone (PSE-OHP)** + +If the PMA has enabled the PSE-OHP alarm notification, the DPU shall autonomously send a PSE-OHP alarm to the PMA when the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-OHP. + +#### **A.7.2.2.2 Loss of power alarm – PSE lost input power (PSE-DGL)** + +If the PMA has enabled the PSE-DGL alarm notification, the DPU shall autonomously send a PSE-DGL alarm to the PMA when the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-DGL. + +#### **A.7.2.3 Common near-end (DPU) failures and alarms** + +##### **A.7.2.3.1 Last reverse power feeding line loss of power failure (LLPF) – fault condition (DPU-LLPF)** + +A DPU-LLPF failure is declared for the DPU when the DPU is about to shut down because the last RPF line has ceased providing power due to one of the following fault conditions: + +- the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-UKN; +- the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-OHP. + +If the PMA has enabled DPU-LLPF failure notification, the DPU shall autonomously indicate to the PMA when a DPU-LLPF failure is declared, thereby identifying the last RPF line that has ceased providing power and indicating for that line the PSE-RPF state (see clause A.7.4.2.2). + +##### **A.7.2.3.2 Loss of power failure – insufficient power (DPU-MLPF)** + +A DPU-MLPF failure is declared for the DPU when the DPU is about to shut down because one or more RPF lines have ceased providing power, each due to one of the following (fault) conditions: + +- the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-UKN; +- the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-OHP; +- the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-DGL. + +If the PMA has enabled DPU-MLPF failure notification, the DPU shall autonomously indicate to the PMA when a DPU-MLPF failure is declared, thereby identifying the one or more RPF lines that have ceased providing power and indicating for those lines the PSE-RPF state (see clause A.7.4.2.2). + +DPU-MLPF shall not be declared if the last reverse power feeding line has ceased providing power and DPU-LLPF or DPU-LLPS is declared. + +NOTE – DPU-MLPF may also be declared in case of a shutdown of multiple or all PSEs at once. In this event, the DPU may not have enough time before it loses power to process the PSE reverse power feeding state of each line to check whether or not PSE lost power dying gasp was received. + +##### **A.7.2.3.3 Loss of power alarm – normal shutdown (DPU-LLPS)** + +If the PMA has enabled the DPU-LLPS alarm notification, the DPU shall autonomously send a DPU-LLPS alarm to the PMA when the last RPF line has ceased providing power due to the following condition: + +- the PSE-RPF state (see clause A.7.4.2.2) becomes PSE-DGL, thereby identifying the last RPF line that has ceased providing power. + +#### **A.7.3 RPF performance monitoring objects** + +##### **A.7.3.1 Measured Time (CURR/PREV\_NE/FE\_15\_L\_TIME)** + +See clause 7.7.1 + +##### **A.7.3.2 Invalid Data flag (PREV\_NE/FE\_15\_L\_INVALID)** + +See clause 7.7.2 + +##### **A.7.3.3 Time Stamp (PREV\_NE/FE\_15\_L\_STAMP)** + +See clause 7.7.3 + +#### **A.7.3.4 DPU Extracted Energy counter (CURR/PREV\_NE\_15\_EE)** + +**Description:** Reports a count of the DPU extracted energy per line at U-O interface or at PSU input in current/previous 15 min interval, expressed in units of mWh. This PM object is optional. The accuracy is defined in [ETSI TS 101 548]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (counter of mWh units). + +**Reference:** None. + +NOTE – The PMA can calculate the average extracted power over current 15 minute interval by the DPU at the U-O interface or at the PSU input by reading out the current 15 minute value and dividing it by the measured time in the current 15 minute interval. + +#### **A.7.3.5 PSE Injected Energy counter (CURR/PREV\_FE\_15\_IE)** + +**Description:** Reports a count of the PSE injected energy per line in current/previous 15 min interval, expressed in units of mWh. This PM object is optional. It is constructed by the DPU by reading the RPF OAM parameter PSE-IE (see clause A.6.2.5). It can only be supported in case the PSE is integrated in the NT (see clause A.7.6.2.1, PSE-NTE equals 1). The accuracy is defined in [ETSI TS 101 548]. + +**Type:** 32-bit unsigned integer. + +**Valid values:** 0...4294967295 (counter of mWh units). + +**Reference:** Clause 6.4 of [ETSI TS 101 548] and clause A.6.2.5. + +NOTE – The PMA can calculate the average extracted power over current 15 minute interval by the DPU at the U-O interface or at the PSU input by reading out the current 15 minute value and dividing it by the measured time in the current 15 minute interval. + +### **A.7.4 RPF status objects** + +#### **A.7.4.1 Per line near-end (DPU) status objects** + +##### **A.7.4.1.1 Actual power class (PE-PC)** + +**Description:** Reports the actual PC of the PE for the line. + +**Type:** Enumeration. + +**Valid values:** 1 (SR1), 2 (SR2), 3 (SR3). + +**Reference:** Clause 7.2 of [ETSI TS 101 548]. + +##### **A.7.4.1.2 Reverse power feeding state (PE-RPF)** + +**Description:** Reports the RPF state of the PE for the line. + +**Type:** enumeration. + +**Valid values:** 0 (not operational), 1 (in START-UP MODE) and 2 (in NORMAL OPERATIONS). + +**Reference:** Clause 6.2.4 of [ETSI TS 101 548]. + +##### **A.7.4.1.3 ReConfiguration state (DPU-RCS)** + +**Description:** Reports the ReConfiguration State for the line. A state change alarm shall be raised indicating a change of the line's Reconfiguration State (see clause A.7.2.1.2). + +**Type:** Enumeration. + +**Valid values:** 0 (Normal mode), 1 (Bypass mode). + +**Reference:** Clause A.3.1 + +#### A.7.4.1.4 PRP Error Status (DPU-PRP-ERROR) + +**Description:** Reports that the DPU has deduced a PRP related ERROR while the DPU is powered on. An alarm shall be raised upon the PRP Error Status indicating an error condition on the line. + +**Type:** Enumeration + +**Valid values:** 0...2: + +- 0 None: no error detected by DPU or PRP completed successfully. +- 1 RPF Class Miss Match: DPU has decoded PRP disconnect trigger of a class that is not supported by the DPU for the given line. +- 2 POTS Reconnect trigger: POTS Reconnect trigger detected by DPU. + +**Reference:** Clause 6.2.5 of [ETSI TS 101 548]. + +#### A.7.4.1.5 Line error status (DPU-LES) + +**Description:** Reports an error condition for the line whereby the DPU is unable to draw continuous and sufficient power from the line. This status object is optional. If supported, an alarm shall be raised upon the Line Error Status indicating an error condition on the line. + +**Type:** Enumeration. + +**Valid values:** 0 (No error), 1 (Error). + +**Reference:** None. + +### A.7.4.2 Per line far-end (PSE) status objects + +#### A.7.4.2.1 Actual power class (PSE-PC) + +**Description:** Reports the actual PC of the PSE. Before the start-up protocol is successfully completed for the first time, the PC is undetermined. + +**Type:** Enumeration. + +**Valid values:** 0 (undetermined), 1 (SR1), 2 (SR2), 3 (SR3). + +**Reference:** Clause 7.2 of [ETSI TS 101 548]. + +#### A.7.4.2.2 Reverse power feeding state (PSE-RPF) + +**Description:** Reports the RPF state of the PSE. + +**Type:** enumeration. + +**Valid values:** 0...5 + +- 0 PSE-UKN: Shutdown for unknown reason + - as initial state; + - when for the line the PE transitions to START-UP MODE after the PE detects loss of voltage, and has not received a PSE-DGL or PSE-OHP indication ( see clause A.6.2.1.1) from the PSE. +- 1 PSE-DGL: Shutdown with dying gasp (normal shutdown) + - when for the line the PE transitions to START-UP MODE after the PE detects loss of voltage and has received a PSE-DGL indication (see clause A.6.2.1.1) from the PSE. +- 2 PSE-OHP: Shutdown with dying gasp with OHP + - when for the line the PE transitions to START-UP MODE after the PE detects loss of voltage and has received a PSE-OHP indication (see clause A.6.2.1.1) from the PSE. +- 3 PSE-PWR: Powered with unknown PSE powering method + +- when for the line the PE transitions to NORMAL OPERATIONS and it is yet unknown whether the PSE is battery or mains powered. + +#### 4 PSE-BAT: Battery powered + +- when for the line the PE transitions to NORMAL OPERATIONS and the PE receives an indication that the PSE is trying to start up the DPU while powered on battery {plain old telephony service remote copper reconfiguration protocol power splitter (PRP PS) field, see clause 6.2.5.1 of [ETSI TS 101 548]}; +- when for the line the PE is in NORMAL OPERATIONS and the PE receives a PSE-BAT indication (see clause 6.2.2) from the PSE. + +#### 5 PSE-ACM: Mains powered + +- when for the line the PE transitions to NORMAL OPERATIONS and the PE receives an indication that the PSE was trying to start up the DPU while powered on mains (PRP PS field, see clause 6.2.5.1 of [ETSI TS 101 548]); +- when for the line the PE is in NORMAL OPERATIONS and the PE receives a PSE-ACM or PSE-BBA indication (see clause A.6.2.1.1) from the PSE. + +**Reference:** Clauses 6.2.4, 6.2.5.1 and 6.3 of [ETSI TS 101 548] and clause A.6.2.1.1. + +#### A.7.4.3 Common near-end (DPU) status objects + +No common near-end (DPU) status objects are defined. + +#### A.7.5 RPF diagnostics objects + +##### A.7.5.1 Per line near-end (DPU) diagnostics objects + +No per line near-end diagnostics objects are defined. + +##### A.7.5.2 Per line far-end (PSE) diagnostics objects + +###### A.7.5.2.1 Latest PSE Start-Up Failure cause (PSE-SUF) + +**Description:** Reports the latest PSE Start-Up Failure indication, detected during "Start-Up". + +**Type:** Enumeration. + +**Valid values:** 0...7 + +- 0 No failure. +- 1 ELC-0 (Open tip-to-ring). +- 2 ELC-1 (Short tip-to-ring). +- 3 ELC-2 (POTS Exchange (foreign) DC voltage). +- 4 ELC-3 (Off-hook phone) (Note). +- 5 Mismatch of the PSE RPF Class with the DPU RPF Class. +- 6 Unknown. +- 7 Failure other than off-hook (Note). + +**Reference:** Clause 6.1.1 of [ETSI TS 101 548] and clause A.6.2.5. + +NOTE – In case the PSE is not integrated in the NT and with POTS RCR (PRP) capability supported (i.e., NT-CPF equals 2 and PSE-PRP equals 2), this indication is deduced by the DPU from the "Last Start Up" (LSU) state 1012 (see Table 20 of [ETSI TS 101 548]). + +###### A.7.5.2.2 Latest PSE ShutDown cause (PSE-SDC) + +**Description:** Reports the latest PSE ShutDown cause, detected during "Normal Operation". + +**Type:** Enumeration. + +**Valid values:** 0...6 + +- 0 No PSE Shutdown yet. +- 1 ELC-0 (Open tip-to-ring). +- 2 ELC-1 (Short tip-to-ring). +- 3 ELC-3 (Off-hook phone). +- 4 Overload time violation as defined in Table 35 of [ETSI TS 101 548]. +- 5 Maintain power signature violation as defined in Table 37 of [ETSI TS 101 548]. +- 6 Unknown. + +**Reference:** Clause 6.1.1 of [ETSI TS 101 548] and clause A.6.2.5. + +#### **A.7.5.3 Common near-end (DPU) diagnostics objects** + +No common near-end (DPU) diagnostics objects are defined. + +#### **A.7.6 RPF inventory objects** + +##### **A.7.6.1 Per line near-end (DPU) inventory objects** + +###### **A.7.6.1.1 Reconfiguration capability (DPU-RC)** + +**Description:** Reports the ReConfiguration capability for the line. + +**Type:** Enumeration. + +**Valid values:** 0 (None), 1 (Broadband Bypass), 2 (POTS RCR). + +**Reference:** Clause 3.1 of [ETSI TS 101 548]. + +##### **A.7.6.2 Per line far-end (PSE) inventory objects** + +###### **A.7.6.2.1 Integrated into NT (NTE-CPF)** + +**Description:** Reports whether the PSE is integrated into the NT, based on the RPF OAM parameter NTE-CPF (see clause A.6.2.5). Until the DPU ME receives an NTE-CPF indication for the first time, it is unknown whether the PSE is integrated into the NT. + +**Type:** Enumeration. + +**Valid values:** 0 (unknown), 1 (PSE not integrated into NT), 2 (PSE integrated into NT). + +**Reference:** Clause A.6.2.5. + +###### **A.7.6.2.2 Battery backup available (PSE-BBA)** + +**Description:** Reports whether battery backup is available at the PSE, based on the PSE trying to start up the PE while powered on battery (PRP PS field, see clause 6.2.5.1 of [ETSI TS 101 548]) and on the PSE-BAT, PSE-ACM and PSE-BBA indications (see clause 6.3 of [ETSI TS 101 548] and clause A.6.2.1.1). Until the PE receives the PRP PS field for the first time and until the PE or DPU ME receive a BAT, ACM, or BBA indication for the first time (whichever occurs first), it is unknown whether battery backup is available at the PSE. + +**Type:** Enumeration. + +**Valid values:** 0 (unknown), 1 (battery backup not available), 2 (BBA). + +**Reference:** Clause 6.3 of [ETSI TS 101 548] and clause A.6.2.1.1. + +###### **A.7.6.2.3 PRP capability (PSE-PRP)** + +**Description:** Reports the PSE PRP capability. In case the PSE is integrated in the NT (i.e., NT-CPF equals 2), the PSE-PRP capability is communicated through RPF OAM from PSE to + +DPU (see clause A.6.2.5). In case the PSE is not integrated in the NT (i.e., NT-CPF equals 2), it is deduced by the DPU from successful PRP start-up, whereby the DPU shall assume that the PRP disconnect trigger is sent by the PSE that is currently providing reverse power to the DPU. Until the PE receives the PRP PS field (see clause A.6.2.5) for the first time, or until the first successful PRP start-up, the PSE PRP capability is unknown. + +**Type:** Enumeration. + +**Valid values:** 0 (unknown), 1 (PRP not supported), 2 (PRP supported). + +**Reference:** Clause 6.2.5 of [ETSI TS 101 548] and clause A.6.2.5. + +#### **A.7.6.3 Common near-end (DPU) inventory objects** + +No common near-end (DPU) inventory objects are defined. + +## **Annex B to Annex R** + +Annexes B to R have been intentionally left blank. + +## Annex S + +### Management for network termination software upgrade process + +(This annex forms an integral part of this Recommendation.) + +#### S.1 Scope + +This annex specifies the management of the NT software upgrade process defined in Annex S of [ITU-T G.9701]. Two images (0 and 1) are maintained by the software management function, so that one can be upgraded while the other is executing. These two images are managed separately using the managed objects defined in clause S.7. + +#### S.2 References + +This annex does not contain any additional references. + +#### S.3 Definitions + +This annex does not contain any additional definitions. + +#### S.4 Abbreviations and acronyms + +This annex does not contain any additional abbreviations and acronyms. + +#### S.5 DPU management architecture + +This annex does not modify the DPU management architecture defined in clause 5. + +#### S.6 Network management protocol + +This annex makes no presumption about which management protocol is used between the PMA and the DPU for transport of G.fast-managed objects. + +#### S.7 Managed objects + +The list of managed objects contains two types of information: + +- 1) software image attributes; +- 2) software image configuration. + +At the DPU-NB interface, the NT software upgrade process is managed through the information given in Table S.1. + +When the software attribute update request flag for a software image (see clause S.7.1.1.7) is set (its value is changed from false to true), the attributes of the corresponding software image shall be updated in the DPU-MIB within 10 s. The update request flag shall be reset (its value changed back to false) by the DPU immediately after the request parameter update is complete. + +Similarly, to request an action (activate, commit, or download) for an NT software image (0 or 1), the corresponding request flag (NT\_SW\_ACTIVATE0/1, NT\_SW\_COMMIT0/1, NT\_SW\_DOWNLOAD0/1) shall be set. The corresponding request flag shall be reset (its value changed back to false) by the DPU immediately after the requested action is complete and the result of the action is available in the DPU-MIB (NT\_SW\_ACTIVATE\_RES0/1, NT\_SW\_COMMIT\_RES0/1, NT\_SW\_DOWNLOAD\_RES0/1). + +Table S.1 indicates the status of each managed object over the DPU-NB interface: + +- R: Read only +- W: Write only + +- R/W: Read and write +- (M): Mandatory +- (O): Optional + +Entries in Table S.1 labelled with names containing the separator "/" represent multiple objects whose names are obtained by considering all combinations of the elements isolated with the separator. For example, the entry labelled with the name A0/1 represents two objects, for the two managed software images (0 and 1), with names A0 and A1. + +**Table S.1 – NT software management objects** + +| Category/object | Defined in clause | DPU-NB interface | +|-------------------------------------|-------------------|------------------| +| Software image attributes | | | +| NT_SW_VERSION0/1 | S.7.1.1.1 | R (M) | +| NT_SW_COMMITTED0/1 | S.7.1.1.2 | R (M) | +| NT_SW_ACTIVE0/1 | S.7.1.1.3 | R (M) | +| NT_SW_VALID0/1 | S.7.1.1.4 | R (M) | +| NT_SW_PRODUCTCODE0/1 | S.7.1.1.5 | R (O) | +| NT_SW_HASH0/1 | S.7.1.1.6 | R (O) | +| UPDATE_NT_SW_ATTR0/1 | S.7.1.1.7 | R/W (M) | +| Software image configuration | | | +| NT_SW_ACTIVATE_COND0/1 | S.7.1.2.1 | R/W (O) | +| NT_SW_ACTIVATE0/1 | S.7.1.2.2 | R/W (M) | +| NT_SW_ACTIVATE_RES0/1 | S.7.1.2.3 | R (M) | +| NT_SW_COMMIT0/1 | S.7.1.2.4 | R/W (M) | +| NT_SW_COMMIT_RES0/1 | S.7.1.2.5 | R (M) | +| NT_SW_IMAGEFILE0/1 | S.7.1.2.6 | R/W (M) | +| NT_SW_DOWNLOAD0/1 | S.7.1.2.7 | R/W (M) | +| NT_SW_DOWNLOAD_RES0/1 | S.7.1.2.8 | R (M) | + +## S.7.1 NT software management objects + +### S.7.1.1 Software image attributes + +#### S.7.1.1.1 Software image version (NT\_SW\_VERSION0/1) + +**Description:** Reports the version of the software image (see clause S.4.1 of [ITU-T G.9701]). + +**Type:** string (14 binary octets). + +**Reference:** Clause S.4.1 of [ITU-T G.9701]. + +#### S.7.1.1.2 Software image committed (NT\_SW\_COMMITTED0/1) + +**Description:** Reports whether the associated software image is committed or uncommitted (see clause S.4.1 of [ITU-T G.9701]). + +**Type:** boolean. + +**Valid values:** false (uncommitted) and true (committed). + +**Reference:** Clause S.4.1 of [ITU-T G.9701]. + +#### S.7.1.1.3 Software image active (NT\_SW\_ACTIVE0/1) + +**Description:** Reports whether the associated software image is active or inactive (see clause S.4.1 of [ITU-T G.9701]). + +**Type:** boolean. + +**Valid values:** false (inactive) and true (active). + +**Reference:** Clause S.4.1 of [ITU-T G.9701]. + +#### S.7.1.1.4 Software image valid (NT\_SW\_VALID0/1) + +**Description:** Reports whether the associated software image is valid or invalid (see clause S.4.1 of [ITU-T G.9701]). + +**Type:** boolean. + +**Valid values:** false (invalid) and true (valid). + +**Reference:** Clause S.4.1 of [ITU-T G.9701]. + +#### S.7.1.1.5 Software product code (NT\_SW\_PRODUCTCODE0/1) + +**Description:** Reports the product code information of the software image (see clause S.4.1 of [ITU-T G.9701]). + +**Type:** string (25 binary octets). + +**Reference:** Clause S.4.1 of [ITU-T G.9701]. + +#### S.7.1.1.6 Software image hash (NT\_SW\_HASH0/1) + +**Description:** Reports the MD5 hash of the software image (see clause S.4.1 of [ITU-T G.9701]). + +**Type:** string (16 binary octets). + +**Reference:** Clause S.4.1 of [ITU-T G.9701]. + +#### S.7.1.1.7 Update request flag for software image attributes (UPDATE\_NT\_SW\_ATTR0/1) + +**Description:** Forces an update of the software image attributes, defined in clauses S.7.1.1.1 to S.7.1.1.6, of the corresponding software image to 0 or 1. See introductory text to clause S.7. + +**Type:** boolean. + +**Valid values:** false (no update forced) or true (update forced). + +**Default value:** false (no update forced). + +### S.7.1.2 Software image configuration + +#### S.7.1.2.1 Activate software conditions (NT\_SW\_ACTIVATE\_COND0/1) + +**Description:** Specifies the conditions under which the activation request for a software image shall be executed (see clauses S.7.1.2.2 and S.5.9 of [ITU-T G.9701]). + +**Type:** enumeration. + +**Valid values:** 0...2 + +0       Activate image unconditionally. + +1       Activate image only if no plain old telephony service/voice over Internet protocol (POTS/VoIP) calls are in progress. + +2       Activate image only if no emergency call is in progress. + +**Default value:** 0 (activate image unconditionally). + +**Reference:** Clause S.5.9 of [ITU-T G.9701]. + +#### **S.7.1.2.2 Request activate software flag (NT\_SW\_ACTIVATE0/1)** + +**Description:** Activate the downloaded software image (see clause S.5.9 of [ITU-T G.9701]). The flag shall be reset after the requested action is complete (see introductory text to clause S.7). + +**Type:** boolean. + +**Valid values:** false (no action) and true (activate software image). + +**Default value:** false (no action). + +**Reference:** Clause S.5.9 of [ITU-T G.9701]. + +#### **S.7.1.2.3 Result of activate software (NT\_SW\_ACTIVATE\_RES0/1)** + +**Description:** Reports the results from the most recent activate software image action (see clause S.5.10 of [ITU-T G.9701] and the introductory text to clause S.7). + +**Type:** enumeration. + +**Valid values:** 0...6, 256 + +- 0 Command processed successfully. +- 1 Command processing error. +- 2 Command not supported. +- 3 Parameter error. +- 4 Reserved for use by ITU-T. +- 5 Unknown managed software image instance. +- 6 Device busy. +- 256 No result available. + +**Reference:** Clause S.5.10 of [ITU-T G.9701]. + +#### **S.7.1.2.4 Request commit software flag (NT\_SW\_COMMIT0/1)** + +**Description:** Commit the downloaded software image (see clause S.5.11 of [ITU-T G.9701]). The flag shall be reset after the requested action is complete (see introductory text to clause S.7). + +**Type:** boolean. + +**Valid values:** false (no action) and true (commit software image). + +**Default value:** false (no action). + +**Reference:** Clause S.5.11 of [ITU-T G.9701]. + +#### **S.7.1.2.5 Result of commit software (NT\_SW\_COMMIT\_RES0/1)** + +**Description:** Reports the results from the most recent commit software image action (see clause S.5.12 of [ITU-T G.9701] and the introductory text to clause S.7). + +**Type:** enumeration. + +**Valid values:** 0...6, 256 + +- 0 Command processed successfully. +- 1 Command processing error. +- 2 Command not supported. +- 3 Parameter error. +- 4 Reserved for use by ITU-T. + +- 5 Unknown managed software image instance. +- 6 Device busy. +- 256 No result available. + +**Reference:** Clause S.5.12 of [ITU-T G.9701]. + +#### **S.7.1.2.6 Location of software image file (NT\_SW\_IMAGEFILE0/1)** + +**Description:** Defines the location of the software image file as Uniform Resource Identifier according to [IETF RFC 3986]. When a request software image download is initiated (see clause S.7.1.2.7), the image software image file is transferred from to the NT from the specified location. + +**Type:** string (up to 256 ASCII characters). + +#### **S.7.1.2.7 Request software image download (NT\_SW\_DOWNLOAD0/1)** + +**Description:** Start the download of the software image file to the NT (see clause S.5.3 of [ITU-T G.9701]). The flag shall be reset after the requested action is complete (see introductory text to clause S.7). + +**Type:** boolean. + +**Valid values:** false (no action) and true (start download software image). + +**Default value:** false (no action). + +**Reference:** Clause S.5.3 of [ITU-T G.9701]. + +#### **S.7.1.2.8 Result of software image download (NT\_SW\_DOWNLOAD\_RES0/1)** + +**Description:** Reports the results from the most recent software image download action (see clause S.5.8 of [ITU-T G.9701] and the introductory text to clause S.7). + +**Type:** enumeration. + +**Valid values:** 0...6, 256, 257 + +- 0 Command processed successfully (CRC correct). +- 1 Command processing error (CRC incorrect, in addition to the normal criteria). +- 2 Command not supported. +- 3 Parameter error. +- 4 Reserved for use by ITU-T. +- 5 Unknown managed software image instance. +- 6 Device busy. +- 256 No result available. +- 257 Software image file could not be accessed at the specified location. + +**Reference:** Clause S.5.8 of [ITU-T G.9701]. + +## Annex T + +### Annex X, Annex D and Annex T of ITU-T G.9701 – Managed objects + +(This annex forms an integral part of this Recommendation.) + +#### T.1 Overview of Annex X, Annex D and Annex T of ITU-T G.9701 managed objects + +Tables T.1, T.2 and T.3 give an overview of the managed objects used to manage the Annex X and Annex D of [ITU-T G.9701] and the DTA cross-layer aspects specified in Annex T of [ITU-T G.9701]. Tables T.1, T.2 and T.3 use the same convention as that used in the tables of the managed object of clause 7. Support of Annex T is optional. Different subsets of the objects shall be supported depending on which Annex (Annex X, Annex D or both) is supported as indicated in Tables T.1 to T.3. + +Table T.1 – Annex X, Annex D and Annex T of ITU-T G.9701 configuration objects + +| Category/object | Defined in clause: | DPU-NB | Supported together with: | +|-------------------------------------------------------|--------------------|---------|--------------------------| +| DTA, Annex X and Annex D management | | | | +| Annex X operation mode (ANNEX_X_MODE) | T.2.1.1 | R/W (M) | Annex X | +| iDTA allowed according to Annex X (IDTA_ALLOWED) | T.2.1.2 | R/W (M) | Annex X | +| Annex D operation mode (ANNEX_D_MODE) | T.2.1.3 | R/W (M) | Annex D | +| cDTA allowed according to Annex D (CDTA_ALLOWED) | T.2.1.4 | R/W (M) | Annex D | +| DRA configuration | | | | +| Preferred Mds for DTA (DTA_PREF_Mds) | T.2.2.1 | R/W (M) | Annex D or X | +| Maximum step size for DTA changes (DTA_SMAX) | T.2.2.2 | R/W (M) | Annex D or X | +| Minimum Mds for DTA (DTA_MIN_Mds) | T.2.2.3 | R/W (M) | Annex D or X | +| Maximum Mds for DTA (DTA_MAX_Mds) | T.2.2.4 | R/W (M) | Annex D or X | +| Minimum expected throughput for DTA (DTA_MINETRds/us) | T.2.2.5 | R/W (M) | Annex D or X | +| Maximum net data rate for DTA (DTA_MAXNDRds/us) | T.2.2.6 | R/W (M) | Annex D or X | +| cDTA procedure control (CDTA_PROC_CTRL) | T.2.2.7 | R/W (M) | Annex D | +| Minimum time between DTA updates (DTA_MIN_TIME) | T.2.2.8 | R/W (O) | Annex D or X | + +**Table T.2 – Annex X, Annex D and Annex T of ITU-T G.9701 status objects** + +| Category/object | Defined in clause: | DPU-NB | Supported together with: | +|--------------------------------------------------|--------------------|--------|--------------------------| +| Annex X operation enabled (ANNEX_X_ENABLED) | T.3.1 | R(M) | Annex X | +| iDTA enabled according to Annex X (IDTA_ENABLED) | T.3.2 | R(M) | Annex X | +| Annex D operation enabled (ANNEX_D_ENABLED) | T.3.3 | R(M) | Annex D | +| cDTA procedure actual type (CDTA_PROC_ACT) | T.3.4 | R(M) | Annex D | + +**Table T.3 – Annex X, Annex D and Annex T of ITU-T G.9701 inventory objects** + +| Category/object | Defined in clause: | DPU-NB | Supported together with: | +|-----------------------------------------------|--------------------|--------|--------------------------| +| FTU-O Annex X support (ANNEX_X_SUPPORT_FTU_O) | T.4.1 | R(M) | Annex X | +| FTU-R Annex X support (ANNEX_X_SUPPORT_FTU_R) | T.4.2 | R(M) | Annex X | +| FTU-O iDTA support (IDTA_SUPPORT_FTU_O) | T.4.3 | R(M) | Annex X | +| FTU-O Annex D support (ANNEX_D_SUPPORT_FTU_O) | T.4.4 | R(M) | Annex D | +| FTU-R Annex D support (ANNEX_D_SUPPORT_FTU_R) | T.4.5 | R(M) | Annex D | + +**T.2 Annex X, Annex D and Annex T of [ITU-T G.9701] configuration objects****T.2.1 DTA, Annex D and Annex X management****T.2.1.1 Annex X operation mode (ANNEX\_X\_MODE)** + +**Description:** Determines whether Annex X operation of [ITU-T G.9701] is enabled. If ANNEX\_D\_MODE is set to AnnexD\_FORCED or AnnexD\_PREFERRED, then ANNEX\_X\_MODE shall be set to AnnexX\_FORBIDDEN. + +**Type:** enumeration. + +**Valid values:** 0, 1, 2 + +- 0 AnnexX\_FORBIDDEN (Operation according to Annex X is not allowed). +- 1 AnnexX\_PREFERRED (Operation according to Annex X is preferred). +- 2 AnnexX\_FORCED (Operation according to Annex X is forced). + +**Default value:** 0 (AnnexX\_FORBIDDEN). + +**Reference:** Clauses X.6.7.1 and T.2.1 of [ITU-T G.9701]. + +**T.2.1.2 iDTA allowed according to Annex X (IDTA\_ALLOWED)** + +**Description:** Determines whether iDTA according to Annex X is allowed. If CDTA\_ALLOWED is set to true (allowed) or ANNEX\_X\_MODE is set to AnnexX\_FORBIDDEN, then IDTA\_ALLOWED shall be set to false (disallowed). + +**Type:** boolean. + +**Valid values:** false (disallowed), true (allowed). + +**Default value:** false (disallowed). + +**Reference:** Clauses X.6.7.2 and T.2.2 of [ITU-T G.9701]. + +#### **T.2.1.3 Annex D operation mode (ANNEX\_D\_MODE)** + +**Description:** Determines whether Annex D operation of [ITU-T G.9701] is enabled. If ANNEX\_X\_MODE is set to AnnexX\_FORCED or AnnexX\_PREFERRED, then ANNEX\_D\_MODE shall be set to AnnexD\_FORBIDDEN + +**Type:** enumeration. + +**Valid values:** 0, 1, 2 + +0 AnnexD\_FORBIDDEN (Operation according to Annex D is not allowed) + +1 AnnexD\_PREFERRED (Operation according to Annex D is preferred) + +2 AnnexD\_FORCED (Operation according to Annex D is forced) + +**Default value:** 0 (AnnexD\_FORBIDDEN). + +**Reference:** Clause D.5.7.1 and T.2.1.1 of [ITU-T G.9701]. + +#### **T.2.1.4 cDTA allowed according to Annex D (CDTA\_ALLOWED)** + +**Description:** Determines whether cDTA according to Annex D is allowed. If IDTA\_ALLOWED is set to true (allowed) or ANNEX\_D\_MODE is set to AnnexD\_FORBIDDEN, then CDTA\_ALLOWED shall be set to false (disallowed). + +**Type:** boolean + +**Valid values:** false (disallowed), true (allowed) + +**Default value:** false (disallowed) + +**Reference:** Clause D.5.7.2 and T.2.2.1 of [ITU-T G.9701]. + +### **T.2.2 DRA configuration** + +#### **T.2.2.1 Preferred Mds for DTA (DTA\_PREF\_Mds)** + +**Description:** Provides the number of downstream symbol positions in a TDD frame requested by the DRA at the first opportunity upon entering showtime of a line on which DTA operation is enabled. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 5...30 (if MF=36 and IDTA\_ALLOWED=True), 5...17 (if MF=23 and IDTA\_ALLOWED=True), 10...31 (if MF=36 and CDTA\_ALLOWED=True) and 6...19 (if MF=23 and CDTA\_ALLOWED=True). + +**Default value:** 28 + +NOTE – If MF=23, a value different from the default value needs to be configured (see 7.1). + +**Reference:** Clause T.2.3 of [ITU-T G.9701]. + +#### **T.2.2.2 Maximum step size for DTA changes (DTA\_SMAX)** + +**Description:** Defines the maximum step size for Mds requested by the DRA for a single DTA update. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 1...25 (if MF=36 and IDTA\_ALLOWED=True), 1...12 (if MF=23 and IDTA\_ALLOWED=True), 1...21 (if MF=36 and CDTA\_ALLOWED=True) and 1...13 (if MF=23 and CDTA\_ALLOWED=True). + +NOTE – If MF=23 or CDTA\_ALLOWED=True, a value different from the default value needs to be configured (see 7.1). + +**Default value:** 25 + +**Reference:** Clause T.2.4 of [ITU-T G.9701]. + +#### **T.2.2.3 Minimum Mds for DTA (DTA\_MIN\_Mds)** + +**Description:** Provides the minimum number of downstream symbol positions Mds in a TDD frame that shall be requested by the DRA. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 5...30 (if MF=36 and IDTA\_ALLOWED=True), 5...17 (if MF=23 and IDTA\_ALLOWED=True), 10...31 (if MF=36 and CDTA\_ALLOWED=True) and 6...19 (if MF=23 and CDTA\_ALLOWED=True). + +**Default value:** 5 + +NOTE – If CDTA\_ALLOWED=True, a value different from the default value needs to be configured (see 7.1). + +**Reference:** Clause T.2.5 of [ITU-T G.9701]. + +#### **T.2.2.4 Maximum Mds for DTA (DTA\_MAX\_Mds)** + +**Description:** Provides the maximum number of downstream symbol positions Mds in a TDD frame that shall be requested by the DRA. + +**Type:** 8-bit unsigned integer. + +**Valid values:** 5...30 (if MF=36 and IDTA\_ALLOWED=True), 5...17 (if MF=23 and IDTA\_ALLOWED=True), 10...31 (if MF=36 and CDTA\_ALLOWED=True) and 6...19 (if MF=23 and CDTA\_ALLOWED=True). + +**Default value:** 30. + +NOTE – If MF=23, a value different from the default value needs to be configured (see 7.1). + +**Reference:** Clauses X.6.7.4, D.5.7.4 and T.2.6 of [ITU-T G.9701]. + +#### **T.2.2.5 Minimum expected throughput for DTA (DTA\_MINETRds/us)** + +**Description:** Defines the value of the minimum expected throughput for DTA operation to constrain the dynamic range of Mds requested by the DRA. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 0 (0 bit/s). + +**Reference:** Clause T.2.7 of [ITU-T G.9701]. + +#### **T.2.2.6 Maximum net data rate for DTA (DTA\_MAXNDRds/us)** + +**Description:** Defines the value of the maximum NDR for DTA operation. + +**Type:** 32-bit unsigned integer. + +**Unit:** 1000 bits/second. + +**Valid values:** 0...4294967295 (0 to $2^{32}-1$ kbit/s). + +**Default value:** 4294967295 (4294967295 kbit/s). + +**Reference:** Clauses X.6.7.5, D.5.7.5 and T.2.8 of [ITU-T G.9701]. + +#### **T.2.2.7 cDTA procedure control (CDTA\_PROC\_CTRL)** + +**Description:** Determines the procedure type that the DRA is allowed to apply. + +**Type:** enumeration. + +**Valid values:** 0, 1, 2 + +0 DRA is allowed to use the one-step or two-step cDTA procedure (see clause D.5.6). + +1 DRA shall use the one-step procedure only (see clause D.5.6). + +2 DRA shall use the two-step procedure only (see clause D.5.6). This value is intended to be used for test purposes. + +**Default value:** 0 (one-step or two-step cDTA procedure). + +**Reference:** T.2.9 of [ITU-T G.9701]. + +#### **T.2.2.8 Minimum time between DTA updates (DTA\_MIN\_TIME)** + +**Description:** Determines the minimum time between any two successive DTA updates during showtime. + +**Type:** 16-bit unsigned integer. + +**Unit:** 0.01 seconds. + +**Valid values:** 0...16383 (0 to 163.83 seconds). + +**Default value:** 0 (0 seconds). + +**Reference:** T.2.10 of [ITU-T G.9701]. + +### **T.3 Annex X, Annex D and Annex T of ITU-T G.9701 status objects** + +#### **T.3.1 Annex X operation enabled (ANNEX\_X\_ENABLED)** + +**Description:** Indicates whether Annex X operation is enabled. + +**Type:** boolean + +**Valid values:** false (disabled), true (enabled) + +**Reference:** Clause X.6.8.1 of [ITU-T G.9701]. + +#### **T.3.2 iDTA enabled according to Annex X (iDTA\_ENABLED)** + +**Description:** Indicates whether iDTA according to Annex X is enabled. + +**Type:** boolean + +**Valid values:** false (disabled), true (enabled) + +**Reference:** Clause X.6.8.2 of [ITU-T G.9701]. + +#### **T.3.3 Annex D operation enabled (ANNEX\_D\_ENABLED)** + +**Description:** Indicates whether Annex D operation is enabled. + +**Type:** boolean + +**Valid values:** false (disabled), true (enabled) + +**Reference:** Clause D.5.8.1 of [ITU-T G.9701]. + +### **T.3.4 cDTA procedure actual type (CDTA\_PROC\_ACT)** + +**Description:** Indicates which cDTA procedure is used by the DRA according to Annex D. + +**Type:** enumeration + +**Valid values:** + +- 0 cDTA is disabled. +- 1 DRA uses one-step procedure. +- 2 DRA uses two-step procedure + +**Reference:** Clause D.5.8.2 of [ITU-T G.9701]. + +## **T.4 Annex X, Annex D and Annex T of ITU-T G.9701 inventory objects** + +### **T.4.1 FTU-O Annex X support (ANNEX\_X\_SUPPORT\_FTU\_O)** + +**Description:** Indicates whether Annex X is supported by the FTU-O. + +**Type:** boolean. + +**Valid values:** false (not supported), true (supported). + +**Reference:** Clause X.7.1.1.1 of [ITU-T G.9701]. + +### **T.4.2 FTU-R Annex X support (ANNEX\_X\_SUPPORT\_FTU\_R)** + +**Description:** Indicates whether Annex X is supported by the FTU-R. This implies support of iDTA according to Annex X. + +**Type:** boolean. + +**Valid values:** false (not supported), true (supported). + +**Reference:** Clause X.7.1.2.1 of [ITU-T G.9701]. + +### **T.4.3 FTU-O iDTA according to Annex X support (IDTA\_SUPPORT\_FTU\_O)** + +**Description:** Indicates whether iDTA according to Annex X is supported by the FTU-O. + +**Type:** boolean. + +**Valid values:** false (not supported), true (supported). + +**Reference:** Clause X.7.1.1.1 of [ITU-T G.9701]. + +### **T.4.4 FTU-O Annex D support (ANNEX\_D\_SUPPORT\_FTU\_O)** + +**Description:** Indicates whether Annex D is supported by the FTU-O. This implies support of cDTA according to Annex D. + +**Type:** boolean + +**Valid values:** false (not supported), true (supported) + +**Reference:** Clause D.6.1.1.1 of [ITU-T G.9701]. + +### **T.4.5 FTU-R Annex D support (ANNEX\_D\_SUPPORT\_FTU\_R)** + +**Description:** Indicates whether Annex D is supported by the FTU-R. This implies support of cDTA according to Annex D. + +**Type:** boolean + +**Valid values:** false (not supported), true (supported) + +**Reference:** Clause D.6.1.2.1 of [ITU-T G.9701]. + +## **Annex U to Annex W** + +Annexes U to W have been intentionally left blank. + +## Annex X + +### Cross-layer link state objects + +(This annex forms an integral part of this Recommendation.) + +#### X.1 Overview of cross-layer link state objects + +Table X.1 gives an overview of the managed objects used to manage the cross-layer functionality specified in Annex Z of [ITU-T G.9701]. It used the same convention as used in the tables of the managed object of the clause 7. + +**Table X.1 – Cross-layer link state objects** + +| Category/object | Defined in clause: | DPU-NB | +|----------------------------------------------|--------------------|---------| +| LRCC management | | | +| Link State Control (LINK_STATE_CTRL) | X.2.1.1 | R/W (O) | +| L0 to L2.1 trigger criteria | | | +| L0_L2.1N_TRIGR_THRESH_QAds/us | X.2.2.1 | R/W (O) | +| L0_L2.1N_TRIGR_PERIOD_QAds/us | X.2.2.2 | R/W (O) | +| L0_L2.1N_TRIGR_PERSIST_QAds/us | X.2.2.3 | R/W (O) | +| L2.1N to L0 trigger criteria | | | +| L2.1N_L0_TRIGR_THRESH_QFds/us | X.2.3.1 | R/W (O) | +| L2.1N_L0_TRIGR_PERSIST_QFds/us | X.2.3.2 | R/W (O) | +| L2.1B to L2.2 trigger criteria | | | +| L2.1B_L2.2_TRIGR_THRESH_QAds/us | X.2.4.1 | R/W (O) | +| L2.1B_L2.2_TRIGR_PERIOD_QAds/us | X.2.4.2 | R/W (O) | +| L2.1B_L2.2_TRIGR_PERSIST_QAds/us | X.2.4.3 | R/W (O) | +| L2.2 to L2.1B trigger criteria | | | +| L2.2_L2.1B_TRIGR_THRESH_QFds/us | X.2.5.1 | R/W (O) | +| L2.2_L2.1B_TRIGR_PERSIST_QFds/us | X.2.5.2 | R/W (O) | +| Addition battery criteria | | | +| L0_L2.1B_TRIGR_PERSIST_BAT | X.2.6.1 | R/W (O) | +| L2.1N_L2.1B_TRIGR_PERSIST_BAT | X.2.6.2 | R/W (O) | +| L2.1B_L2.1N_TRIGR_PERSIST_BAT | X.2.6.3 | R/W (O) | +| L2.2_L2.1N_TRIGR_PERSIST_BAT | X.2.6.4 | R/W (O) | + +#### X.2 Cross-layer low power mode control + +##### X.2.1 LRCC management + +###### X.2.1.1 Link State Control (LINK\_STATE\_CTRL) + +**Description:** Selects the operation mode for link state control. + +**Type:** enumeration. + +Valid values: 0,1 + +0 Vendor discretionary control. + +1 Control according to Annex Z of [ITU-T G.9701]. + +**Default value:** 0 (Vendor discretionary control). + +**Reference:** Table Z.14 of [ITU-T G.9701]. + +## **X.2.2 L0 to L2.1N trigger criteria** + +### **X.2.2.1 L0\_L2.1N\_TRIGR\_THRESH\_QAds/us** + +**Description:** Defines the L0\_L2.1N bytes arriving trigger criteria for the L0 to L2.1N trigger criteria: the threshold for bytes arriving (QADA or QAUA for downstream and upstream processing respectively) in trigger period L0\_L2.1N\_TRIGR\_PERIOD\_QA aggregated over all queues. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1000 bytes. + +**Valid values:** 1...127 (1 to 127 kbytes). + +**Default value:** 32 (32 kbytes). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +### **X.2.2.2 L0\_L2.1N\_TRIGR\_PERIOD\_QAds/us** + +**Description:** Defines the period over which the bytes arriving (QADA or QAUA for downstream and upstream processing respectively) metrics are accumulated for the L0 to L2.1N trigger criteria. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 6...255 (6 to 255 ms). + +**Default value:** 255 (255 ms). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +### **X.2.2.3 L0\_L2.1N\_TRIGR\_PERSIST\_QAds/us** + +**Description:** Defines the persistency guard time for the bytes arriving trigger criteria (QADA or QAUA for downstream and upstream processing respectively), for the L0 to L2.1N trigger criteria. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 second. + +**Valid values:** 1...4095 (1 to 4095 seconds). + +**Default value:** 1200 (1200 seconds). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +## **X.2.3 L2.1N to L0 trigger criteria** + +### **X.2.3.1 L2.1N\_L0\_TRIGR\_THRESH\_QFds/us** + +**Description:** Defines the L2.1N\_L0 queue fill trigger criteria: the threshold for queue fill (QFDA or QFUA for downstream and upstream processing respectively) aggregated over all queues. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 byte. + +**Valid values:** 64...65535 (bytes). + +**Default value:** 32768 (bytes). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +#### **X.2.3.2 L2.1N\_L0\_TRIGR\_PERSIST\_QFds/us** + +**Description:** Defines the persistency guard time for L2.1N to L0 trigger criteria. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 0...255 (0 to 255 ms). + +**Default value:** 100 (100 ms). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +#### **X.2.4 L2.1B to L2.2 trigger criteria** + +##### **X.2.4.1 L2.1B\_L2.2\_TRIGR\_THRESH\_QAds/us** + +**Description:** Defines the L2.1B\_L2.2 bytes arriving trigger criteria for the L2.1B to L2.2 trigger criteria: the threshold for bytes arriving (QADA or QAUA for downstream and upstream processing respectively) in trigger period L2.1B\_L2.2\_TRIGR\_PERIOD\_QA aggregated over all queues. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 byte. + +**Valid values:** 1...255 (1 to 255 bytes). + +**Default value:** 1 (1 byte). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +##### **X.2.4.2 L2.1B\_L2.2\_TRIGR\_PERIOD\_QAds/us** + +**Description:** Defines the period over which the bytes arriving (QADA or QAUA for downstream and upstream processing respectively) metrics are accumulated for the L2.1B to L2.2 trigger criteria. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 6...255 (6 to 255 ms in step of 1 ms). + +**Default value:** 6 (6 ms). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +##### **X.2.4.3 L2.1B\_L2.2\_TRIGR\_PERSIST\_QAds/us** + +**Description:** Defines the persistency guard time for the L2.1B to L2.2 trigger criteria. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 second. + +**Valid values:** 0...255 (0 to 255 s). + +**Default value:** 1 (1 s). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +#### **X.2.5 L2.2 to L2.1B trigger criteria** + +##### **X.2.5.1 L2.2\_L2.1B\_TRIGR\_THRESH\_QFds/us** + +**Description:** Defines the L2.2\_L2.1B queue fill trigger criteria: the threshold for queue fill (QFDA or QFUA for downstream and upstream processing respectively) aggregated over all queues. + +**Type:** 16-bit unsigned integer. + +**Unit:** 1 byte. + +**Valid values:** 64...65535 (64 to 65535 bytes). + +**Default value:** 255 (255 bytes). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +#### **X.2.5.2 L2.2\_L2.1B\_TRIGR\_PERSIST\_QFds/us** + +**Description:** Defines the persistency guard time for the L2.2 to L2.1B trigger criteria. + +**Type:** 8-bit unsigned integer. + +**Unit:** 10 milliseconds. + +**Valid values:** 1...255 (10 to 2550 ms in step of 10 ms). + +**Default value:** 60 (600 ms). + +**Reference:** Clause Z.6.2.3.1 of [ITU-T G.9701]. + +#### **X.2.6 Additional battery (BAT) criteria** + +##### **X.2.6.1 L0\_L2.1B\_TRIGR\_PERSIST\_BAT** + +**Description:** Defines the persistency guard time for the L0 to L2.1B battery trigger criterion. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 0...255 (0 to 255 ms). + +**Default value:** 1 (1 ms). + +**Reference:** Clause Z.6.2.3.2 of [ITU-T G.9701]. + +##### **X.2.6.2 L2.1N\_L2.1B\_TRIGR\_PERSIST\_BAT** + +**Description:** Defines the persistency guard time for the L2.1N to L2.1B battery trigger criterion. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 0...255 (0 to 255 ms). + +**Default value:** 1 (1 ms). + +**Reference:** Clause Z.6.2.3.2 of [ITU-T G.9701]. + +#### **X.2.6.3 L2.1B\_L2.1N\_TRIGR\_PERSIST\_BAT** + +**Description:** Defines the persistency guard time for the L2.1B to L2.1N battery trigger criterion. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 0...255 (0 to 255 ms). + +**Default value:** 1 (1 ms). + +**Reference:** Clause Z.6.2.3.2 of [ITU-T G.9701]. + +#### **X.2.6.4 L2.2\_L2.1N\_TRIGR\_PERSIST\_BAT** + +**Description:** Defines the persistency guard time for the L2.2 to L2.1N battery trigger criterion. + +**Type:** 8-bit unsigned integer. + +**Unit:** 1 millisecond. + +**Valid values:** 0...255 (0 to 255 ms). + +**Default value:** 1 (1 ms). + +**Reference:** Clause Z.6.2.3.2 of [ITU-T G.9701]. + +## Appendix I + +### Broadband Forum considerations on the FTTdp deployment scenario + +(This appendix does not form an integral part of this Recommendation.) + +As the DPU is deployed closer to the customer premises, the number of ports on a DPU gets smaller and more DPUs are deployed throughout the network. Distribution points are at locations where local power is not available. In this case, the DPU may be reverse powered where the power comes from the customer premises, sharing the same copper pair with the data service, or the DPU may be forward powered where the power comes from a nearby network power node via copper pairs to the DPU from the network power node. + +Reverse powering is one aspect of FTTdp that must be accounted for in the management architecture. Reverse powering of the DPU means that it can be powered down at any time without the network operator's advance knowledge or control. Most network management systems would treat such a spontaneous loss of power as a fault condition and raise an alarm, which is clearly not appropriate for FTTdp. This gave rise to the concept of a PMA, which acts as a management proxy for the DPU when it was unpowered. Figure I.1 shows the high-level PMA architecture as defined in the Broadband Forum + +![Figure I.1 – High-level PMA architecture diagram](7818b1bd115c04ee738bcf90f51d945b_img.jpg) + +The diagram illustrates the high-level PMA architecture. At the top, a purple circle labeled 'OSS' is connected via a double-headed arrow to a blue rectangle labeled 'NMS'. The 'NMS' is connected via a double-headed arrow to a pink rectangle labeled 'PMA aggregation'. The 'PMA aggregation' is connected via a double-headed arrow to a stack of three green rectangles, the front-most labeled 'PMA'. This 'PMA' is connected via a double-headed arrow to a green rectangle labeled 'DPU'. The 'DPU' is connected via a double-headed arrow to a green rectangle labeled 'CPE'. Below the 'CPE' rectangle, the text 'G.997.2(15)\_FI.1' is displayed. + +Figure I.1 – High-level PMA architecture diagram + +**Figure I.1 – High-level PMA architecture (source: Broadband Forum)** + +In this architecture, there is a one to one correspondence between a PMA instance and the DPU it manages. These instances are then aggregated up to higher order management systems. This aggregation function may be realized as part of a PMA server that manages multiple DPUs, an intermediate system that aggregates PMAs residing on lower order systems, or as part of the NMS function. + +The PMA uses NETCONF plus a Broadband Forum defined YANG model to manage the DPU. The definitions of the managed objects defined in clause 7 translate into YANG data model syntax (see [b-IETF RFC 6020]), for example as follows: + +``` +leaf { + description ""; + type { + range ""; + } + units ""; + default ""; + reference ""; +} +``` + +## Bibliography + +- [b-ITU-T G.993.2] Recommendation ITU-T G.993.2 (2015), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [b-ITU-T M.3010] Recommendation ITU-T M.3010 (2000), *Principles for a telecommunications management network*. +- [b-IETF RFC 1157] IETF RFC 1157 (1990), *A simple network management protocol (SNMP)*. +- [b-IETF RFC 3339] IETF RFC 3339 (2002), *Date and time on the Internet: Timestamps*. +- [b-IETF RFC 6020] IETF RFC 6020 (2010), *YANG – A data modelling language for the network configuration protocol (NETCONF)*. +- [b-IETF RFC 6021] IETF RFC 6021 (2010), *Common YANG data types*. +- [b-IETF RFC 7223] IETF RFC 7223 (2014), *A YANG Data Model for Interface Management*. +- [b-BBF TR-301] Broadband Forum TR-301 Issue 1 (2015), *Architecture and Requirements for Fiber to the Distribution Point*. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9971-201007-I_PDF-E/raw.md b/marked/G/T-REC-G.9971-201007-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..59076d1e8fd1921f5c25566b4d44b4fe73f319dc --- /dev/null +++ b/marked/G/T-REC-G.9971-201007-I_PDF-E/raw.md @@ -0,0 +1,899 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9971** + +(07/2010) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – In premises networks + +# --- **Requirements of transport functions in IP home networks** + +Recommendation ITU-T G.9971 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| In premises networks | G.9950–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +### Recommendation ITU-T G.9971 + +# Requirements of transport functions in IP home networks + +## Summary + +Recommendation ITU-T G.9971 specifies the functional requirements of transport functions in an IP home network associated with the wired access network based on the generic architecture described by Recommendation ITU-T G.9970: "Generic home network transport architecture". This Recommendation first clarifies the position of the home network in end-to-end transport networks as well as the home network functional architecture, and then provides the functional requirements for the transport capabilities of some key components in the home network, such as the access gateway (AGW), IP terminal, etc. Moreover, it mentions some other functional requirements, such as QoS control, management and security so that the operators can reliably provide their services all the way to the IP terminal. + +## History + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.9971 | 2010-07-29 | 15 | + +## Keywords + +Access gateway, control, Ethernet, home network, IP, management, NT, ONT, ONU, security. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2011 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-----------------------------------------------------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 4 Abbreviations and acronyms ..... | 2 | +| 5 Conventions ..... | 3 | +| 6 Position of home network in end-to-end networks..... | 3 | +| 7 Typical IP home network configurations ..... | 4 | +| 8 IP home network functional architecture..... | 5 | +| 9 IP network configuration and IP address assignment..... | 8 | +| 10 QoS control..... | 11 | +| 10.1 Two kinds of QoS guaranteed services ..... | 12 | +| 10.2 Three device types for QoS control..... | 12 | +| 10.3 Home network QoS control for each QoS service ..... | 13 | +| 10.4 Parameters for QoS control ..... | 14 | +| 10.5 Functional components for QoS control..... | 14 | +| 10.6 Typical QoS control functional components of each device for QoS
service type 2 and 3 ..... | 16 | +| 10.7 QoS control requirements for QoS service type 2..... | 19 | +| 11 Home network management..... | 20 | +| 11.1 Home network management architecture..... | 20 | +| 11.2 Requirements for RM-RA management interface..... | 22 | +| 11.3 Requirements for LM-LA management interface ..... | 23 | +| 12 Security management..... | 24 | +| Appendix I – Relationship among home network standards ..... | 25 | +| Bibliography..... | 27 | + + + +# Requirements of transport functions in IP home networks + +# 1 Scope + +This Recommendation specifies the functional requirements of transport functions in an IP home network associated with the wireline access network based on the generic architecture described by [ITU-T G.9970]: "Generic home network transport architecture". As popularity of broadband services such as FTTH, VDSL and DOCSIS 3.0 increases, this Recommendation covers the cases of home networks connecting to wireline access networks such as these. Services on this home network are triple play services, such as voice, video and data transfer services. However, incorporation of fixed mobile convergence (FMC) using in-home base station is for further study. Once a home network is connected to an access network, mechanisms need to exist that allow the network operator to manage fault, performance, transfer capability, addressing and security for the home network. In many cases, these will be the same as those used to manage the access network. Note that although the NT/ONT, which terminates an access network, is also studied in this Recommendation from the view point of the home network management, it is out of scope that devices are directly connected to NT/ONT without an AGW. Moreover, the scope only includes the case where Ethernet MAC service (which may be over a variety of physical layers) is provided at the WAN side of NT/ONT. + +While [ITU-T G.9960], [ITU-T G.9961] and [ITU-T G.9972] specify the physical layer, such as transceiver, and the mapping between the physical layer and Layer 2 protocols, this Recommendation studies the subject of IP and Ethernet bridging technologies, which does not overlap with the scope of these Recommendations. + +This Recommendation first clarifies the position of the home network in end-to-end transport networks as well as the home network functional architecture, and then provides the functional requirements for the transport capabilities of some key components in the home network, such as the access gateway (AGW), IP terminal, etc. Moreover, it mentions some other functional requirements, such as QoS control, management and security so that the operators can reliably provide their services all the way to the IP terminal. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.9960] Recommendation ITU-T G.9960 (2009), *Unified high-speed wire-line based home networking transceivers – Foundation*. +- [ITU-T G.9961] Recommendation ITU-T G.9961 (2010), *Data link layer (DLL) for unified high-speed wire-line based home networking transceivers*. +- [ITU-T G.9970] Recommendation ITU-T G.9970 (2009), *Generic home network transport architecture*. +- [ITU-T G.9972] Recommendation ITU-T G.9972 (2010), *Coexistence mechanism for wireline home networking transceivers*. + +- [ITU-T H.622] Recommendation ITU-T H.622 (2008), *A generic home network architecture with support for multimedia services.* +- [ITU-T I.371] Recommendation ITU-T I.371 (2004), *Traffic control and congestion control in B-ISDN.* +- [ITU-T Y.1541] Recommendation ITU-T Y.1541 (2006), *Network performance objectives for IP-based services.* +- [ITU-T Y.1563] Recommendation ITU-T Y.1563 (2009), *Ethernet frame transfer and availability performance.* +- [ITU-T Y.2001] Recommendation ITU-T Y.2001 (2004), *General overview of NGN.* +- [BBF TR-069] Broadband Forum TR-069 (2007), *CPE WAN Management Protocol v1.1, including its Amendment 2.* +- [MEF 10.2] Technical Specification MEF 10.2 (2009), *Ethernet Service Attributes Phase 2.0.* + +# 3 Definitions + +This Recommendation defines the following terms: + +**3.1 access gateway (AGW):** The AGW associates the access network with the IP home network and handles IP-related protocol packets for these networks. The AGW provides IP and/or Ethernet services to the home network side. Its definition in this Recommendation is equal to the Internet gateway device (IGD)/residential gateway (RG) in the Broadband Forum or the home gateway in the HGI. Note that it is different from the terminologies used in [b-ITU-T Y.2091]: its "access gateway" means edge router, while its "residential gateway" means terminal adaptor. + +**3.2 network termination/optical network termination (NT/ONT):** The NT/ONT terminates the optical access network and then generally provides the Layer 2 services to the home network side. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------|------------------------------------| +| AGW | Access Gateway | +| FMC | Fixed Mobile Convergence | +| FTTH | Fibre to The Home | +| ICMP | Internet Control Message Protocol | +| IP | Internet Protocol | +| IPCP | Internet Protocol Control Protocol | +| IPv6CP | IPv6 Control Protocol | +| LA | Local Agent | +| LLDP | Link Layer Discovery Protocol | +| LM | Local Manager | +| L2F | Layer 2 Forwarding | +| L3F | Layer 3 Forwarding | +| L1T | Layer 1 Termination | + +| | | +|--------|--------------------------------------| +| L2T | Layer 2 Termination | +| L2TP | Layer 2 Tunneling Protocol | +| L3T | Layer 3 Termination | +| MAC | Media Access Control | +| NAPT | Network Address and Port Translation | +| NAT | Network Address Translation | +| NAT-PT | NAT-Protocol Translation | +| NGN | Next Generation Networks | +| NSP | Network Service Provider | +| NT | Network Termination | +| ONT | Optical Network Termination | +| PD | Prefix Delegation | +| PPP | Point-to-Point Protocol | +| QoS | Quality of Service | +| RA | Remote Agent | +| RM | Remote Manager | +| RMS | Remote Management Server | +| RSVP | Resource Reservation Protocol | +| SIP | Session Initiation Protocol | +| SLAAC | StateLess Address AutoConfiguration | + +# 5 Conventions + +**local area network (LAN):** It represents the home network side of AGW. + +**wide area network (WAN):** It represents the access network side of AGW. + +# 6 Position of home network in end-to-end networks + +This clause describes a managed home network within the context of end-to-end transport networks as shown in Figure 6-1. The end-to-end network consists of the home network, the AGW, access networks, the core network and some application servers. + +![Diagram of end-to-end network management showing two home networks connected via access and core networks to application servers. The diagram shows two 'Home network' blocks (yellow) on the left and right. Each contains a 'Primary/IP terminal' (grey) and an 'IP home network' (pink) connected to an 'AGW' (grey). The AGW connects to an 'Access network' (blue) containing an 'NT/ONT' (white). The two access networks connect to a central 'Core network' (green). Above the core network are three 'Application servers' (grey). Red dashed lines with arrows indicate management paths from the application servers, through the core and access networks, to the primary terminals in both home networks. A label 'G.9971(10)_F6-1' is in the bottom right corner.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Diagram of end-to-end network management showing two home networks connected via access and core networks to application servers. The diagram shows two 'Home network' blocks (yellow) on the left and right. Each contains a 'Primary/IP terminal' (grey) and an 'IP home network' (pink) connected to an 'AGW' (grey). The AGW connects to an 'Access network' (blue) containing an 'NT/ONT' (white). The two access networks connect to a central 'Core network' (green). Above the core network are three 'Application servers' (grey). Red dashed lines with arrows indicate management paths from the application servers, through the core and access networks, to the primary terminals in both home networks. A label 'G.9971(10)\_F6-1' is in the bottom right corner. + +**Figure 6-1 – Home network to be managed in end-to-end networks** + +The primary terminal is the end-point where the service from the NSP is terminated, according to [ITU-T H.622]. That is, the end-to-end services are provided between two primary terminals or between each application server and each primary terminal. The AGW connects the IP home network with the access network, which is terminated by NT/ONT. Moreover, the primary terminal defined in the application layer normally attaches to the IP home network, in which case the primary terminal is called IP terminal in transport layer, according to [ITU-T G.9970]. Therefore, the IP terminal, the IP home network, the AGW, the access networks including NT/ONT, the core network and their relevant control networks could be managed by the NSPs. In order to achieve this, this Recommendation specifies the functions needed in each device within the IP home network, such as the IP terminal, the Ethernet bridge, the AGW as well as NT/ONT. The requirements in this Recommendation are more detailed than [ITU-T G.9970]. Note that the case is out of scope where the IP terminal is directly connected to NT/ONT without AGW. Moreover, only the case where Ethernet MAC is used at the WAN side of NT/ONT is included in this Recommendation. + +# 7 Typical IP home network configurations + +This clause describes configurations of the IP home network to be studied in this Recommendation. Figure 7-1 shows two kinds of IP home network configuration. Configuration 1 shows that one Ethernet bridge either aggregates the traffic from multiple IP terminals to the AGW or bridges the traffic between two IP terminals. Note that multiple Ethernet bridges can be put in cascade between the IP terminal and the AGW. On the other hand, configuration 2 shows that each IP terminal is directly connected to the AGW. Although this figure shows the separate type AGW, this Recommendation also studies the aggregate type AGW that combines NT/ONT. + +![Diagram of Configuration 1: Two IP terminals are connected to a central Ethernet bridge. The Ethernet bridge is connected to a Separate type AGW, which is in turn connected to an NT/ONT.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg) + +``` + +graph LR + IP1[IP terminal] --- EB[Ethernet bridge] + IP2[IP terminal] --- EB + EB --- STA[Separate type AGW] + STA --- NT[NT/ONT] + +``` + +Diagram of Configuration 1: Two IP terminals are connected to a central Ethernet bridge. The Ethernet bridge is connected to a Separate type AGW, which is in turn connected to an NT/ONT. + +Configuration 1: Each IP terminal is connected to AGW via Ethernet bridge. + +![Diagram of Configuration 2: Two IP terminals are connected directly to a Separate type AGW. The Separate type AGW is connected to an NT/ONT.](e9314c83043183351ed74908e9bf2f90_img.jpg) + +``` + +graph LR + IP1[IP terminal] --- STA[Separate type AGW] + IP2[IP terminal] --- STA + STA --- NT[NT/ONT] + +``` + +Diagram of Configuration 2: Two IP terminals are connected directly to a Separate type AGW. The Separate type AGW is connected to an NT/ONT. + +Configuration 2: Each IP terminal is directly connected to AGW. + +G.9971(10)\_F7-1 + +**Figure 7-1 – Typical IP home network configurations** + +# 8 IP home network functional architecture + +Key devices can be defined by using the following functional components: + +- Layer 1 termination (L1T): Termination functions of physical layer, such as Ethernet PHY. +- Layer 2 termination (L2T): Termination functions of Ethernet port, such as MAC address assignment. +- Layer 2 forwarding (L2F): Ethernet bridging functions using MAC forwarding table as well as L2 QoS processing, such as L2/L2 QoS mapping, which will be discussed in clause 10. Note that L2F of Ethernet bridge also contains L2/L2 mapping function between Ethernet and wireless within LAN, for example. +- Layer 3 termination (L3T): Termination functions of IP port, such as IP address assignment. +- Layer 3 forwarding (L3F): IP routing functions using IP routing table as well as L3 QoS processing, such as L3/L3 and L3/L2 QoS mappings, which will be discussed in clause 10. + +By using these functional components, IP terminal can be composed of L1T, L2F, L2T, L3F and L3T, as shown in Figure 8-1 (A). On the other hand, Ethernet bridge and NT/ONT can be composed of L1T and L2F, as shown in Figure 8-1 (B). + +![Diagram showing functional components of IP terminal and Ethernet bridge/NT/ONT. (A) IP terminal: A stack of functional blocks. L3T and L3F are at the top. Below them, L2T and L2F are shown. At the bottom, L1T is shown. (B) Ethernet bridge and NT/ONT: A stack of functional blocks. L2F is at the top. Below it, two L1T blocks are shown side-by-side.](18442e4e239480f0c3c95b547aa8fde2_img.jpg) + +(A) IP terminal + +(B) Ethernet bridge and NT/ONT + +Diagram showing functional components of IP terminal and Ethernet bridge/NT/ONT. (A) IP terminal: A stack of functional blocks. L3T and L3F are at the top. Below them, L2T and L2F are shown. At the bottom, L1T is shown. (B) Ethernet bridge and NT/ONT: A stack of functional blocks. L2F is at the top. Below it, two L1T blocks are shown side-by-side. + +G.9971(10)\_F8-1 + +**Figure 8-1 – Functional components of IP terminal, Ethernet bridge and NT/ONT** + +It is complicated to show transport layer functions of AGW in one figure, because there are various kinds of AGW. As shown in Figure 8-2, there are three fundamental types of separate type AGW, which does not combine NT/ONT. + +- a) NAT/NAPT type: Source or destination IP address of an IP packet is changed after being forwarded in AGW in accordance with NAT/NAPT. Note that a MAC address in Layer 2 is terminated in each port. + +- b) IP router type: An IP packet is just forwarded in AGW without changing its source and destination IP addresses. Note that a MAC address in Layer 2 is terminated in each port. +- c) Ethernet bridge type: An Ethernet packet is just forwarded in AGW without changing its source and destination MAC addresses. + +![Figure 8-2: Functional components of separate type AGW. (A) NAT/NAPT type: Shows two vertical stacks of layers. The left stack has L1T (green), L2T (purple), and L3T (light blue). The right stack has L1T (green), L2T (purple), and L3T (light blue). A central L3F (blue) block is positioned above the L3T blocks. (B) IP router type: Shows two vertical stacks. The left stack has L1T (green) and L2T (purple). The right stack has L1T (green) and L2T (purple). A central L3F (blue) block is positioned above the L2T blocks. (C) Ethernet bridge type: Shows two vertical stacks. The left stack has L1T (green). The right stack has L1T (green). A central L2F (purple) block is positioned above the L1T blocks. Below the diagrams is the text G.9971(10)_F8-2.](007b053fe94a8348f75128a584503fd0_img.jpg) + +Figure 8-2: Functional components of separate type AGW. (A) NAT/NAPT type: Shows two vertical stacks of layers. The left stack has L1T (green), L2T (purple), and L3T (light blue). The right stack has L1T (green), L2T (purple), and L3T (light blue). A central L3F (blue) block is positioned above the L3T blocks. (B) IP router type: Shows two vertical stacks. The left stack has L1T (green) and L2T (purple). The right stack has L1T (green) and L2T (purple). A central L3F (blue) block is positioned above the L2T blocks. (C) Ethernet bridge type: Shows two vertical stacks. The left stack has L1T (green). The right stack has L1T (green). A central L2F (purple) block is positioned above the L1T blocks. Below the diagrams is the text G.9971(10)\_F8-2. + +**Figure 8-2 – Functional components of separate type AGW** + +On the other hand, Figure 8-3 shows three types of aggregate type AGW combining NT/ONT. Each type in Figure 8-3 corresponds to that in Figure 8-2. For example, Figure 8-3 (B) shows that an IP packet received at the WAN-side of NT/ONT is forwarded in Layer 2 and then is forwarded in Layer 3 to the LAN-side of AGW. Moreover, Figure 8-3 (C), Ethernet bridge type AGW combined with NT/ONT, shows that IP packets directly flow from WAN to LAN or from LAN to WAN. Although this case is only similar to the NT/ONT case without the AGW, some security function is required for Figure 8-3 (C) case in the AGW. + +![Figure 8-3: Functional components of aggregate type AGW. (A) NAT/NAPT type: Shows a LAN-side stack (L1T, L2T, L3T) and a WAN-side stack (L1T, L2F). A central L3F (blue) block is positioned above the L3T and L2F blocks. (B) IP router type: Shows a LAN-side stack (L1T, L2T) and a WAN-side stack (L1T, L2F). A central L3F (blue) block is positioned above the L2T and L2F blocks. (C) Ethernet bridge type: Shows a LAN-side stack (L1T) and a WAN-side stack (L1T). A central L2F (purple) block is positioned above the L1T blocks. Below the diagrams is the text G.9971(10)_F8-3.](1439cb942d9e363bbb3161b5540dd8c6_img.jpg) + +Figure 8-3: Functional components of aggregate type AGW. (A) NAT/NAPT type: Shows a LAN-side stack (L1T, L2T, L3T) and a WAN-side stack (L1T, L2F). A central L3F (blue) block is positioned above the L3T and L2F blocks. (B) IP router type: Shows a LAN-side stack (L1T, L2T) and a WAN-side stack (L1T, L2F). A central L3F (blue) block is positioned above the L2T and L2F blocks. (C) Ethernet bridge type: Shows a LAN-side stack (L1T) and a WAN-side stack (L1T). A central L2F (purple) block is positioned above the L1T blocks. Below the diagrams is the text G.9971(10)\_F8-3. + +**Figure 8-3 – Functional components of aggregate type AGW** + +In contrast to the above WAN-side features of AGW, three types of LAN-side physical ports can be identified for AGW, as shown in Figure 8-4. Although Figure 8-4 depicts the configuration of LAN-side ports for NAT/NAPT separate type AGW, it is also applied to its corresponding aggregate type AGW as well as IP router separate/aggregate type AGWs. In each type, an IP packet from each LAN-side port can be forwarded to the WAN-side port in Layer 3. However, the following distinctions can be found in each type. Note that each type takes as an example that AGW has three LAN-side physical ports. + +- (X) Hub type: As LAN-side ports are physically connected with each other, an Ethernet packet from each LAN-side port is broadcast to all the LAN-side ports. +- (Y) Bridge type: As LAN-side ports are connected with each other through Layer 2 forwarding (L2F), an Ethernet packet from each LAN-side port is transported to the target LAN-side port based on its MAC forwarding table. +- (Z) Multiple segments type: As LAN-side ports are connected with each other through Layer 3 forwarding (L3F), an IP packet from each LAN-side port is routed to the target LAN-side port based on its IP routing table. + +![Figure 8-4: LAN side physical ports of NAT/NAPT separate type AGW. The diagram shows three types of connections: (X) Hub type where three L1T devices connect to a single L2T port; (Y) Bridge type where three L1T devices connect to an L2F bridge which then connects to an L2T port; and (Z) Multiple segments type where three L1T devices each connect to their own L2T and L3T modules, which all connect to a central L3F module. The output of the L3F module passes through another L3T, L2T, and L1T module. A label G.9971(10)_F8-4 is present.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Figure 8-4: LAN side physical ports of NAT/NAPT separate type AGW. The diagram shows three types of connections: (X) Hub type where three L1T devices connect to a single L2T port; (Y) Bridge type where three L1T devices connect to an L2F bridge which then connects to an L2T port; and (Z) Multiple segments type where three L1T devices each connect to their own L2T and L3T modules, which all connect to a central L3F module. The output of the L3F module passes through another L3T, L2T, and L1T module. A label G.9971(10)\_F8-4 is present. + +**Figure 8-4 – LAN side physical ports of NAT/NAPT separate type AGW** + +In order to help understanding, Figure 8-5 shows three key devices, such as IP terminal, Ethernet bridge and NAT/NAPT aggregate type AGW with bridge type LAN ports as well as their relationship with IP home network and Ethernet home network. + +![Figure 8-5: An example of home network functional architecture. The diagram shows an IP terminal, an Ethernet bridge, and a NAT/NAPT aggregate type AGW connected to an IP home network and an Ethernet home network. The IP terminal contains L1T, L2T, L2F, L3T, and L3F modules. The Ethernet bridge contains L1T and L2F modules. The NAT/NAPT aggregate type AGW contains L1T, L2T, L2F, L3T, and L3F modules. The IP home network is represented by a blue oval, and the Ethernet home network is represented by a grey oval. A label G.9971(10)_F8-5 is present.](ff0952ef692c9d960ce5f6708bcc9711_img.jpg) + +Figure 8-5: An example of home network functional architecture. The diagram shows an IP terminal, an Ethernet bridge, and a NAT/NAPT aggregate type AGW connected to an IP home network and an Ethernet home network. The IP terminal contains L1T, L2T, L2F, L3T, and L3F modules. The Ethernet bridge contains L1T and L2F modules. The NAT/NAPT aggregate type AGW contains L1T, L2T, L2F, L3T, and L3F modules. The IP home network is represented by a blue oval, and the Ethernet home network is represented by a grey oval. A label G.9971(10)\_F8-5 is present. + +**Figure 8-5 – An example of home network functional architecture** + +To summarize, the following transport layer functional requirements can be identified for the IP home network key devices, such as IP terminal, Ethernet bridge, AGW and NT/ONT. + +R8-1: IP terminal requires transport layer 1, 2 and 3 functions, as shown in Figure 8-1 (A). + +R8-2: Ethernet bridge and NT/ONT requires transport layer 1 and 2 functions, as shown in Figure 8-1 (B). + +R8-3: Separate type AGW, which is one of the three types shown in Figure 8-2, requires corresponding transport layer functions. + +R8-4: Aggregate type AGW, which is one of the three types shown in Figure 8-3, requires corresponding transport layer functions. + +R8-5: Separate/aggregate type AGWs may have LAN-side transport layer functions shown in Figure 8-4. + +![Figure 8-6: Functional architecture of separate type AGW. The diagram shows a layered model for an Access Gateway (AGW). At the top, a dashed red line separates the 'AGAF (Access gateway application layer function)' from the 'AGTF (Access gateway transport layer function)'. Above the line are two yellow boxes labeled 'Management' and 'Security'. Below the line, the 'AGTF' section contains a stack of layers: 'QoS control' (orange box) at the top, followed by a row of three boxes: 'L3T' (light blue), 'L3F' (dark blue), and 'L3T' (light blue). Below this is a row of three boxes: 'L2T' (purple), 'L2F' (dark purple), and 'L2T' (purple). At the bottom is a row of two boxes: 'L1T' (green) on the left and 'L1T' (green) on the right. A small label 'G.9971(10)_F8-6' is at the bottom right.](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg) + +Figure 8-6: Functional architecture of separate type AGW. The diagram shows a layered model for an Access Gateway (AGW). At the top, a dashed red line separates the 'AGAF (Access gateway application layer function)' from the 'AGTF (Access gateway transport layer function)'. Above the line are two yellow boxes labeled 'Management' and 'Security'. Below the line, the 'AGTF' section contains a stack of layers: 'QoS control' (orange box) at the top, followed by a row of three boxes: 'L3T' (light blue), 'L3F' (dark blue), and 'L3T' (light blue). Below this is a row of three boxes: 'L2T' (purple), 'L2F' (dark purple), and 'L2T' (purple). At the bottom is a row of two boxes: 'L1T' (green) on the left and 'L1T' (green) on the right. A small label 'G.9971(10)\_F8-6' is at the bottom right. + +**Figure 8-6 – Functional architecture of separate type AGW** + +In addition to the transport layer 1, 2 and 3 functions described above, some associated functions, such as QoS control, management and security, are also needed. This is illustrated in Figure 8-6, which shows separate type AGW as an example. Note that as this Recommendation focuses on transport layer 2 and 3, its scope of QoS control functions is only on layer 2 and 3. Moreover, although management and security functions are related to transport layer 1, 2 and 3 as well as the functions above layer 4, this Recommendation handles only layer 2 and 3 aspects for them. Accordingly, the following requirement can be identified. + +R8-6: Layer 2 and 3 of each device associated with the IP home network, such as IP terminal, Ethernet bridge, AGW and NT/ONT, require QoS control, management and security when needed. Figure 8-6 illustrates this for separate type AGW as an example. + +Before discussing these three issues, it is better to clarify IP network configuration in access and home network. Clause 9 describes IP configuration and its assignment in the IP home network, considering possible services. Based on it, clause 10 discusses QoS control for each key device, such as IP terminal, Ethernet bridge, AGW and NT/ONT. In the same manner, clause 11 discusses the remote and local management, while clause 12 discusses the security aspect. + +# 9 IP network configuration and IP address assignment + +This clause describes IP network configuration as well as how to assign IP addresses for each IP network configuration. IP network configuration in the IP home network can be categorized based on how IP connection is established in the access network and the home network by the end user or NSP. Note that this clause describes only IP address assignment that is necessary for transporting IP packets, which is described in clause 8. Some other IP addresses necessary for loopback or management purposes will be described in clause 11. + +According to its overview described in clause 8.3 of [ITU-T G.9970], the following three fundamental cases can be identified. + +- (A) Native IPv4/IPv6 connection to AGW (see Figure 9-1): The upper figure shows that a native IPv4 address is assigned at the WAN-side port of the AGW by using NSP's DHCPv4, while local IPv4 addresses are assigned at AGW's LAN-side port and at the IP terminal by using end-user's DHCPv4. The lower figure shows that NSP's DHCPv6-PD (prefix delegation) provides IPv6 prefix for the home network, while IPv6 addresses are assigned at the IP terminal by using the end-user's DHCPv6 or SLAAC (stateless address + +autoconfiguration) based on the provided IPv6 prefix. NAT/NAPT type AGW is used for the former, while IP Router type AGW is used for the latter. + +![Figure 9-1: Native IPv4/IPv6 connection to AGW. The diagram shows two cases: Native IPv4 and Native IPv6. In the IPv4 case, an IP terminal is connected to the LAN-side of a NAT/NAPT type AGW via an IP link flow. The terminal uses DHCPv4 for its IP address, and the AGW's LAN-side port also uses DHCPv4. The WAN-side of the AGW is connected to another network. In the IPv6 case, an IP terminal is connected to the LAN-side of an IP router type AGW via an IP link flow. The terminal uses SLAAC or DHCPv6 for its IP address, and the AGW's LAN-side port uses DHCPv6. The WAN-side of the AGW is connected to a network providing DHCPv6-PD. A legend indicates that a red circle represents an IP address.](bd0b93e7a46ede276d0a3b79ac487bd9_img.jpg) + +Native IPv4 case + +Native IPv6 case + +● IP address G.9971(10)\_F9-1 + +Figure 9-1: Native IPv4/IPv6 connection to AGW. The diagram shows two cases: Native IPv4 and Native IPv6. In the IPv4 case, an IP terminal is connected to the LAN-side of a NAT/NAPT type AGW via an IP link flow. The terminal uses DHCPv4 for its IP address, and the AGW's LAN-side port also uses DHCPv4. The WAN-side of the AGW is connected to another network. In the IPv6 case, an IP terminal is connected to the LAN-side of an IP router type AGW via an IP link flow. The terminal uses SLAAC or DHCPv6 for its IP address, and the AGW's LAN-side port uses DHCPv6. The WAN-side of the AGW is connected to a network providing DHCPv6-PD. A legend indicates that a red circle represents an IP address. + +**Figure 9-1 – Native IPv4/IPv6 connection to AGW** + +- (B) Either IPv4 over PPP or IPv6 over PPP connection to AGW (see Figure 9-2): The upper figure shows that an IPv4 address for IPv4 over a PPP connection is assigned at the WAN-side port of the AGW by using NSP's IPCP, while local IPv4 addresses are assigned at the AGW's LAN-side port and at the IP terminal by using the end-user's DHCPv4, the same as the above (A). The lower figure shows that unnumbered IPv6 over a PPP connection is established at the WAN-side port of the AGW by using NSP's IPv6CP. Moreover, NSP's DHCPv6-PD provides IPv6 prefix for the home network, while IPv6 addresses are assigned at the IP terminal by using the end-user's DHCPv6 or SLAAC based on the provided IPv6 prefix. As in case (A), NAT/NAPT type AGW is used for the former, while IP router type AGW is used for the latter. + +![Figure 9-2: Either IPv4 over PPP or IPv6 over PPP connection to AGW. The diagram shows two cases: IPv4 over PPP and IPv6 over PPP. In the IPv4 case, an IP terminal is connected to the LAN-side of a NAT/NAPT type AGW via an IP link flow. The terminal uses DHCPv4 for its IP address, and the AGW's LAN-side port also uses DHCPv4. The WAN-side of the AGW is connected to a network via an IPv4 PPP connection, where it uses IPCP. In the IPv6 case, an IP terminal is connected to the LAN-side of an IP router type AGW via an IP link flow. The terminal uses SLAAC or DHCPv6 for its IP address, and the AGW's LAN-side port uses DHCPv6. The WAN-side of the AGW is connected to a network via an IPv6 PPP connection, where it uses IPv6CP. The network also provides DHCPv6-PD. A legend indicates that a red circle represents an IP address.](75f0cb39f1cd165dfe4a6aa6c4d9388d_img.jpg) + +IPv4 over PPP case + +IPv6 over PPP case + +● IP address G.9971(10)\_F9-2 + +Figure 9-2: Either IPv4 over PPP or IPv6 over PPP connection to AGW. The diagram shows two cases: IPv4 over PPP and IPv6 over PPP. In the IPv4 case, an IP terminal is connected to the LAN-side of a NAT/NAPT type AGW via an IP link flow. The terminal uses DHCPv4 for its IP address, and the AGW's LAN-side port also uses DHCPv4. The WAN-side of the AGW is connected to a network via an IPv4 PPP connection, where it uses IPCP. In the IPv6 case, an IP terminal is connected to the LAN-side of an IP router type AGW via an IP link flow. The terminal uses SLAAC or DHCPv6 for its IP address, and the AGW's LAN-side port uses DHCPv6. The WAN-side of the AGW is connected to a network via an IPv6 PPP connection, where it uses IPv6CP. The network also provides DHCPv6-PD. A legend indicates that a red circle represents an IP address. + +**Figure 9-2 – Either IPv4 over PPP or IPv6 over PPP connection to AGW** + +- (C) Either IPv4 over PPP or IPv6 over PPP connection to IP terminal (see Figure 9-3): The upper figure shows that an IPv4 address for IPv4 over a PPP connection is assigned at the IP terminal by using NSP's IPCP. In the same way, the lower figure shows that an IPv6 address for IPv6 over a PPP connection is assigned at the IP terminal by using NSP's IPv6CP to establish the PPP session and either SLAAC or DHCPv6 for the IPv6 address. Ethernet bridge type AGW is used for both cases. + +![Figure 9-3: Two diagrams showing network configurations for IPv4 and IPv6 over PPP connections to an IP terminal via an Ethernet bridge type AGW.](5cab96b2d23174c25919840ecd50aa48_img.jpg) + +The diagram illustrates two network configurations for connecting an IP terminal to a WAN through an Ethernet bridge type AGW. + +**IPv4 over PPP case:** On the left, an 'IP terminal' (green box) is connected to the 'LAN-side' of an 'Ethernet bridge type AGW' (orange box) via an 'IP-link flow' (blue cylinder). The 'WAN-side' of the AGW is connected to an 'IPCP' (light blue box) via an 'IPv4 PPP' (blue cylinder) connection. An orange circle representing an 'IP address' is shown on the IP terminal. + +**IPv6 over PPP case:** On the left, an 'IP terminal' (green box) is connected to the 'LAN-side' of an 'Ethernet bridge type AGW' (orange box) via an 'IP-link flow' (blue cylinder). The 'WAN-side' of the AGW is connected to 'DHCPv6' (light blue box) and 'IPv6CP' (light blue box) via an 'IPv6 PPP' (blue cylinder) connection. An orange circle representing an 'IP address' is shown on the IP terminal, and a pink box labeled 'SLAAC' is also connected to it. + +A legend at the bottom left indicates that an orange circle represents an 'IP address'. The diagram is labeled 'G.9971(10)\_F9-3' at the bottom right. + +Figure 9-3: Two diagrams showing network configurations for IPv4 and IPv6 over PPP connections to an IP terminal via an Ethernet bridge type AGW. + +**Figure 9-3 – Either IPv4 over PPP or IPv6 over PPP connection to IP terminal** + +Moreover, there are some other types of IP network configuration, which can be derived from the fundamental three cases described above. The first case is IPv6 over IPv4 where IPv6 terminal wants to communicate with WAN-side IPv6 servers through IPv4 WAN. Figure 9-4 shows this in more detail where an IPv4 address of IPv4 over PPP is assigned at the WAN-side port of the AGW first, and then the NSP's DHCPv6-PD over L2TP over this IPv4 provides IPv6 prefix for the home network, while IPv6 addresses are assigned at the IP terminal by using the end-user's DHCPv6 or SLAAC based on the provided IPv6 prefix. IPv6 IP terminal can communicate with IPv6 servers in WAN by using IPv6 over IPv4 L2TP. The second case is IPv6/v4 NAT-PT (protocol translation) where the IPv4 terminal wants to communicate with IPv6 application servers in WAN. Figure 9-5 shows this in more detail where an IPv4 address of IPv4 over PPP is assigned at the WAN-side port of the AGW by using the NSP's IPCP, while local IPv4 addresses are assigned at the AGW's LAN-side port and at the IP terminal by using the end-user's DHCPv4. Moreover, as an IPv6 address over L2TP over IPv4 is assigned at the WAN-side port of the AGW, IPv4 IP terminal can communicate with IPv6 application servers in WAN by using this IPv6 over L2TP over IPv4. IP router type AGW is used for Figure 9-4, while NAT/NAPT type AGW is used for Figure 9-5. + +![Figure 9-4: IPv6 over L2TP over IPv4 to AGW with IPv6 to IP terminal. The diagram shows an IP terminal on the LAN-side connected to an IP router type AGW. The IP terminal has SLAAC and DHCPv6. The AGW has DHCPv6-PD and IPCP. The connection between the IP terminal and the AGW is an IP link flow. The connection between the AGW and the WAN-side is IPv6 over IPv4 L2TP and IPv4 PPP. A red circle indicates an IP address on the IP terminal.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +Figure 9-4: IPv6 over L2TP over IPv4 to AGW with IPv6 to IP terminal. The diagram shows an IP terminal on the LAN-side connected to an IP router type AGW. The IP terminal has SLAAC and DHCPv6. The AGW has DHCPv6-PD and IPCP. The connection between the IP terminal and the AGW is an IP link flow. The connection between the AGW and the WAN-side is IPv6 over IPv4 L2TP and IPv4 PPP. A red circle indicates an IP address on the IP terminal. + +**Figure 9-4 – IPv6 over L2TP over IPv4 to AGW with IPv6 to IP terminal** + +![Figure 9-5: IPv6 over L2TP over IPv4 to AGW with IPv4 to IP terminal. The diagram shows an IP terminal on the LAN-side connected to a NAT/NAPT type AGW. The IP terminal has DHCPv4. The AGW has SLAAC and DHCPv6. The connection between the IP terminal and the AGW is an IP link flow. The connection between the AGW and the WAN-side is IPv6 over IPv4 L2TP and IPv4 PPP. A red circle indicates an IP address on the IP terminal.](2cde062fd82833415971a8bd1a2cafab_img.jpg) + +Figure 9-5: IPv6 over L2TP over IPv4 to AGW with IPv4 to IP terminal. The diagram shows an IP terminal on the LAN-side connected to a NAT/NAPT type AGW. The IP terminal has DHCPv4. The AGW has SLAAC and DHCPv6. The connection between the IP terminal and the AGW is an IP link flow. The connection between the AGW and the WAN-side is IPv6 over IPv4 L2TP and IPv4 PPP. A red circle indicates an IP address on the IP terminal. + +**Figure 9-5 – IPv6 over L2TP over IPv4 to AGW with IPv4 to IP terminal** + +# 10 QoS control + +This clause describes the architecture for QoS control in the IP home network, and then lists the functional requirements for the AGW as well as other devices. QoS control can be discussed not only for the IP and Ethernet layers but also for other layer 2 protocols, e.g., IEEE 802.11, and lower layer protocols. Therefore, QoS mapping should be specified between each two layers. However, as the scope of this Recommendation is IP and Ethernet layers, it only discusses the QoS mapping between these two layers as shown in Figure 10-1. QoS mappings other than this should refer to other standard documents, such as DLNA, UPnP and [ITU-T G.9960]. For example, mapping between IP and Ethernet is applied to the interface between L3F and L2T within the IP terminal, and to the interface between L3T and L2T within the AGW in Figure 8-5. + +![Figure 10-1: Scope of QoS control. The diagram shows a yellow box labeled 'Scope of this Recommendation' containing 'IP' and 'Ethernet' layers with a 'Mapping' arrow between them. Below the box is 'Lower layer protocols' with a 'Mapping' arrow pointing to it. To the right is 'Other layer 2 protocols' with a 'Mapping' arrow pointing to it from the Ethernet layer.](21ad58fee90f2be50708ff541d225507_img.jpg) + +Figure 10-1: Scope of QoS control. The diagram shows a yellow box labeled 'Scope of this Recommendation' containing 'IP' and 'Ethernet' layers with a 'Mapping' arrow between them. Below the box is 'Lower layer protocols' with a 'Mapping' arrow pointing to it. To the right is 'Other layer 2 protocols' with a 'Mapping' arrow pointing to it from the Ethernet layer. + +**Figure 10-1 – Scope of QoS control** + +## 10.1 Two kinds of QoS guaranteed services + +There are two kinds of QoS guaranteed services: one is that the QoS is guaranteed in the end-to-end along the communication path between users or between a user and an application server in the WAN, the other is that the QoS is guaranteed by hop-by-hop in the network. The former, the end-to-end QoS guaranteed service, is realized by standardized parameterized QoS control protocols, such as SIP and RSVP for IP, as well as admission control. The parameterized QoS control protocols guaranteed end-to-end QoS after the communication path is admitted by admission control. Note that end-to-end QoS is guaranteed irrespective of network types, network configurations and the implementation of each network element. On the other hand, the latter, the hop-by-hop QoS guaranteed service, is realized by standardized prioritized QoS control protocols, such as Diffserv for IP and VLAN service for Ethernet. Note that as the prioritized QoS control protocols guaranteed only hop-by-hop QoS in the network, QoS cannot be guaranteed in the end-to-end of the network. + +## 10.2 Three device types for QoS control + +QoS control is performed in the Ethernet bridge, NT/ONT and IP terminal as well as in various kinds of AGW in the home network. These devices are grouped into three categories based on QoS control types in each layer, as shown in Figure 10-2. + +- a) Layer 3 QoS control device: Only IP packet QoS control is performed at L3F. Examples of this type are the following separate type AGWs: (A) NAT/NAPT type and (B) IP router type in Figure 8-2 as well as (X) Hub type and (Z) Multiple segments type in Figure 8-4. +- b) Layer 2 and 3 QoS control device: Both Ethernet and IP QoS control is performed at L2F and L3F, respectively. Examples of this type are (A) IP terminal in Figure 8-1 as well as (Y) bridge type of separate type AGW in Figure 8-4. In addition to these, this type of device also includes all the aggregate type AGWs that correspond to separate type AGWs described in the above Layer 3 QoS control device. +- c) Layer 2 QoS control device: Only Ethernet QoS control is performed at L2F. Examples of this type are (B) Ethernet bridge or NT/ONT in Figure 8-1. In addition to these, this type of device also includes (C) Ethernet bridge type of separate type AGW in Figure 8-2 as well as the aggregate type AGW corresponding to this separate type AGW. + +![Diagram illustrating three device types for QoS control based on network layers.](9cd90f495b95ad2116ff780248c26d95_img.jpg) + +The diagram shows three vertical stacks of network layers, each with a different QoS control configuration. Each stack consists of three layers: Layer 3 (IP) at the top, Layer 2 (Ethernet) in the middle, and Layer 1 at the bottom. In stack (a), only Layer 3 is highlighted in yellow. In stack (b), both Layer 3 and Layer 2 are highlighted in yellow. In stack (c), only Layer 2 is highlighted in yellow. A legend at the bottom left shows a yellow box labeled 'QoS control layer'. + +(a) Layer 3 QoS control + +(b) Layers 2 and 3 QoS control + +(c) Layer 2 QoS control + +QoS control layer + +G.9971(10)\_F10-2 + +Diagram illustrating three device types for QoS control based on network layers. + +**Figure 10-2 – Three device types for QoS control** + +## 10.3 Home network QoS control for each QoS service + +There are three methods to perform QoS control in the home network depending on the QoS services provided by WAN and the QoS control supported by LAN. These are shown in Figure 10-3. + +- 1) QoS service type 1: Best-effort services are provided by WAN, while LAN supports non-QoS control. In such a case, there is no way to provide for QoS guaranteed services between two IP terminals. +- 2) QoS service type 2: Multiple QoS guaranteed services are provided by the WAN. LAN also supports QoS control, but WAN cannot control it. It is noted that managed best-effort services (i.e., Class 5 specified in [ITU-T Y.1541]) are also one of the classes in the QoS guaranteed services in the WAN. Although QoS control is terminated at the AGW, QoS guaranteed services can be provided between two IP terminals if using QoS mapping at each AGW. Note that QoS mapping is for L2/L2 or L3/L3; it does not map across layers. This type of service corresponds to "NGN Release 1 model", which is specified by [ITU-T Y.2001]. +- 3) QoS service type 3: QoS guaranteed services are provided by WAN. Moreover, LAN supports QoS control, which WAN can also control. Accordingly, QoS guaranteed services can be terminated at the IP terminal. AGW, IP terminal and other devices in the home network will cooperatively perform QoS guaranteed control for the LAN-WAN traffic to use QoS guaranteed services in WAN, taking into account the traffic within the LAN. This type corresponds to "NGN Release 2 model" providing end-to-end NGN services, which is also specified by [ITU-T Y.2001]. + +Note that QoS guaranteed services mean either end-to-end QoS guaranteed service realized by parameterized QoS or hop-by-hop QoS guaranteed service realized by prioritized QoS. + +![Figure 10-3: Relationship between QoS service types and QoS control. The diagram illustrates three network architectures for QoS control between two IP terminals connected via a WAN through Access Gateways (AGWs).](10781f43062bf3e9601a1e086710556c_img.jpg) + +The diagram illustrates three network architectures for QoS control between two IP terminals connected via a WAN through Access Gateways (AGWs). + +**QoS service type 1:** The diagram shows a path from an IP terminal through a LAN (Non QoS control) to an AGW, then through a WAN (Best-effort service, Non QoS control) to another AGW, and finally through a LAN (Non QoS control) to another IP terminal. No QoS control is applied across the path. + +**QoS service type 2:** The diagram shows a path from an IP terminal through a LAN (QoS control) to an AGW. At the AGW, QoS mapping occurs. The path then enters the WAN (QoS guaranteed service) as a QoS controlled path. At the second AGW, another QoS mapping occurs, and the path continues through the LAN (QoS control) to the destination IP terminal. Multiple QoS controlled paths are shown within the WAN. + +**QoS service type 3:** The diagram shows a path from an IP terminal through a LAN (QoS control) to an AGW, then through a WAN (QoS guaranteed service) as a single QoS controlled path, and finally through a LAN (QoS control) to the destination IP terminal. The QoS control is maintained end-to-end. + +Figure 10-3: Relationship between QoS service types and QoS control. The diagram illustrates three network architectures for QoS control between two IP terminals connected via a WAN through Access Gateways (AGWs). + +G.9971(10)\_F10-3 + +Figure 10-3 – Relationship between QoS service types and QoS control + +## 10.4 Parameters for QoS control + +This clause describes two kinds of parameters used for QoS control: one is traffic descriptors characterizing user traffic flows; the other is QoS parameters representing quality objectives for the end-to-end QoS guaranteed services based on SLA. + +Recommended traffic descriptors are listed as follows. Although these parameters have been specified for [MEF 10.2], these can be also applied to IP. + +- CIR: Committed information rate +- CBS: Committed burst size +- EIR: Excess information rate +- EBS: Excess burst size + +Recommended QoS parameters can be identified in some ITU-T Recommendations. [ITU-T Y.1541] specifies QoS parameters for IP as follows: + +- IPTD: IP packet transfer delay +- IPDV: IP packet delay variation +- IPLR: IP packet loss ratio +- IPER: IP packet error ratio + +On the other hand, [ITU-T Y.1563] specifies QoS parameters for Ethernet as follows: + +- FTD: Frame transfer delay +- FDV: Frame delay variation +- FLR: Frame loss ratio +- FER: Frame error ratio + +### 10.5 Functional components for QoS control + +Based on [ITU-T I.371], this clause describes functional components for QoS control as follows. Figure 10-4 shows a functional architecture for QoS control, where the queuing block contains the functional components, such as 4), 5) and 6) below. Note that it is symmetric from LAN to WAN and from WAN to LAN in general. Traffic descriptors in clause 10.4 are used in 1), 5), 6) and 7) below, while QoS parameters are used in 7) below. Both traffic descriptors and QoS parameters from the control and/or management planes are first received by equipment manager, which then transfers them to admission control as well as sets them onto policing, bandwidth control and traffic shaping for the end-to-end QoS guaranteed services. Moreover, as a special case, the equipment manager also sets traffic descriptors onto bandwidth control and traffic shaping for the hop-by-hop QoS guaranteed services. + +- 1) **Policing:** Policing function detects traffic according to certain rules and applies rules to these traffic flows that may cause packets to be dropped, marked, or receive other treatment. Some traffic descriptors for Ethernet and/or IP are provisioned for detecting such traffic flows before user communication is initiated. This function can be located at the ingress of AGW LAN/WAN sides for example. +- 2) **Classification:** Classification function recognizes the type of each traffic flow and assigns "priority" to each. This recognition is performed according to values of specific fields in the Ethernet frame or IP packet or both of them. This function can be located at the ingress of AGW LAN/WAN sides for example. +- 3) **Marking:** Marking function writes "priority" in each Ethernet frame or IP packet according to the result of "classification". Otherwise, a specific "priority" value is provisioned. This function can be located at the ingress of AGW LAN/WAN sides for example. + +- 4) **Priority control:** Priority control function controls input of traffic flows to queues according to the priority level either assigned by "Classification" or written by "Marking". Strict priority (SP) is a typical mechanism for this function. +- 5) **Bandwidth control:** Bandwidth control function controls output of traffic flows from stored queues in order to guarantee a minimum bandwidth based on CIR and CBS of traffic descriptors. Bandwidth control function assigns bandwidth for traffic flows by using scheduling mechanisms, such as weighted fair queuing (WFQ), weighted round robin (WRR), deficit round robin (DRR), etc. +- 6) **Traffic shaping:** Traffic shaping function also controls output of traffic flows from stored queues, similar to bandwidth control. However, the purposes of this traffic shaping function are the restriction of traffic flows below the maximum transfer rate as well as the reduction of delay variation in every traffic flow. +- 7) **Admission control:** Admission control function manages and judges whether to accept or reject each managed traffic flow for the end-to-end QoS guaranteed services based on the traffic descriptors and QoS parameters before user communication is initiated. One example is the SIP case. The management plane provisions QoS parameters onto the admission control via equipment manager. After admission control receives the traffic descriptors from the control plane via the equipment manager, it judges to accept the traffic flow by comparing the received traffic descriptors with the already-provisioned QoS parameters as well as analysing whether or not the network resources can be used via another control plane. In case of acceptance, the admission control sends its acceptance message to the policing and queuing. Another example is RSVP case. After admission control receives the traffic descriptors and QoS parameters from the control plane via the equipment manager, it judges to accept the traffic flow by analysing whether or not the network resources can be used by using another control plane. In case of acceptance, the admission control sends its acceptance message to the policing and queuing. Judgement algorithms in admission control are out of scope in this Recommendation. +- 8) **Traffic measurement:** Based on [ITU-T Y.1540], traffic measurement function counts incoming and outgoing traffic to evaluate offered traffic load. Several counting units can be specified, such as the number of bytes, the number of Ethernet frames or IP packets. Examples of counting mechanisms are jumping window and sliding window as described in [ITU-T I.371]. + +![Functional architecture for QoS control diagram showing Management plane, Control plane, and QoS control components: Equipment manager, Admission control, Policing, Marking Classification, Queuing, and Traffic measurement.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg) + +The diagram illustrates the functional architecture for QoS control. At the top, a yellow box labeled 'Management plane' is connected to a central 'QoS control' block. Below the Management plane, a 'Control plane' (blue box) is shown on the left and right. The 'QoS control' block contains several functional components: 'Equipment manager' (orange box), 'Admission control' (orange box), 'Policing' (yellow box), 'Marking Classification' (blue box), 'Queuing' (green box), and 'Traffic measurement' (yellow box). Arrows indicate the flow of information: 'Traffic descriptors and/or QoS parameter' from the Management plane to the Equipment manager; 'Traffic descriptors and/or QoS parameter' from the Equipment manager to the Admission control; 'Setting of traffic descriptors' from the Equipment manager to the Policing, Marking Classification, and Queuing components; 'Acceptance/rejection' from the Admission control to the Queuing component; and 'Traffic shaping', 'Bandwidth control', and 'Priority control' from the Queuing component to the Traffic measurement component. The input traffic flow enters from the left, passes through the Policing, Marking Classification, and Queuing components, and exits as the output traffic flow on the right. The label 'G.9971(10)\_F10-4' is in the bottom right corner. + +Functional architecture for QoS control diagram showing Management plane, Control plane, and QoS control components: Equipment manager, Admission control, Policing, Marking Classification, Queuing, and Traffic measurement. + +**Figure 10-4 – Functional architecture for QoS control** + +All of these functional components are not always required for each device. Clause 10.6 describes the functional components necessary for each QoS service type in clause 10.3. Note that as QoS service type 1 "Best-effort service" requires only traffic measurement functions, it is not worthwhile studying it. Therefore, clause 10.6 focuses on QoS service type 2 and 3. + +### 10.6 Typical QoS control functional components of each device for QoS service type 2 and 3 + +This clause identifies QoS control functional components necessary for each device, which is categorized as device type (a), (b) and (c) in clause 10.2. Required functional components depend on QoS service type 2 and 3, as described in clause 10.3. Each QoS service type 2 and 3 is divided into two. One is end-to-end QoS guaranteed service, which is realized by using parameterized QoS control protocol. The other is hop-by-hop QoS guaranteed service, which is realized by using prioritized QoS control protocol. + +Table 10-1 shows control functional components for QoS service type 2 in case of (A) end-to-end QoS guaranteed service as well as in case of (B) hop-by-hop QoS guaranteed service. Moreover, Table 10-2 shows control functional components for QoS service type 3 in case of (A) end-to-end QoS guaranteed service as well as in case of (B) hop-by-hop QoS guaranteed service. Note that Tables 10-1 and 10-2 show only separate type AGWs. However, QoS control functional components necessary for aggregate type AGWs can be easily derived from these tables. For example, both aggregate type AGW (A) and (B) in Figure 8-3 correspond to separate type AGW (A) and (B) in Figure 8-2, while aggregate type AGW (C) in Figure 8-3 corresponds to separate type AGW (C) in Figure 8-2. + +**Table 10-1 – Control functional components for QoS service type 2** + +#### **(A) In case of end-to-end QoS guaranteed service** + +| Device | Separate type AGW | | | NT/ONT | +|-------------------------------|-------------------|-----------------------|-----------------|-----------------| +| | (a) | (b) | (c) | (c) | +| Device type (see clause 10.2) | | | | | +| Policing | R | R for L3;
O for L2 | R | R | +| Classification | R | R for L3;
O for L2 | R | R | +| Marking | O a) | O a) | O a) | O a) | +| Priority control | R | R for L3;
O for L2 | R | R | +| Bandwidth control | R | R for L3;
O for L2 | R | R | +| Traffic shaping | R | R for L3;
O for L2 | R | R | +| Admission control | R | R for L3;
O for L2 | R | R | +| Traffic measurement | O c) | O c) | O c) | O c) | + +#### **(B) In case of hop-by-hop QoS guaranteed service** + +| Device | Separate type AGW | | | NT/ONT | +|-------------------------------|-------------------|-----------------------|-----------------|-----------------| +| | (a) | (b) | (c) | (c) | +| Device type (see clause 10.2) | | | | | +| Policing | O | O | O | O | +| Classification | R | R for L3;
O for L2 | R | R | +| Marking | O a) | O a) | O a) | O a) | +| Priority control | R | R for L3;
O for L2 | R | R | +| Bandwidth control | O b) | O b) | O b) | O b) | +| Traffic shaping | O b) | O b) | O b) | O b) | +| Admission control | N/A | N/A | N/A | N/A | +| Traffic measurement | O c) | O c) | O c) | O c) | + +R Recommended + +O Optional + +N/A Not Applicable + +a) If specific value in Ethernet MAC and/or IP header has to be overwritten, the support of this functional component is recommended. + +b) If transfer bandwidth has to be limited and/or surplus bandwidth has to be shared with already provisioned traffic flows, the support of these functional components is recommended. + +c) If traffic flows have to be measured for traffic management, the support of this functional component is recommended. This function should not affect user traffic flows. + +**Table 10-2 – Control functional components for QoS service type 3** + +#### **(A) In case of end-to-end QoS guaranteed service** + +| Device | IP terminal | Ethernet bridge | Separate type AGW | | | NT/ONT | +|-------------------------------|-------------------------------------|-----------------|-------------------|-------------------------------------|-----------------|-----------------| +| | | | (a) | (b) | (c) | | +| Device type (see clause 10.2) | (b) | (c) | (a) | (b) | (c) | (c) | +| Policing | N/A | R | R | R for L3;
O for L2 | R | R | +| Classification | R for L3;
O for L2 | R | R | R for L3;
O for L2 | R | R | +| Marking | O a) | O a) | O a) | O a) | O a) | O a) | +| Priority control | R for L3;
O for L2 | R | R | R for L3;
O for L2 | R | R | +| Bandwidth control | R for L3;
O b) for L2 | R | R | R for L3;
O b) for L2 | R | R | +| Traffic shaping | R for L3;
O b) for L2 | R | R | R for L3;
O b) for L2 | R | R | +| Admission control | R for L3;
O for L2 | R | R | R for L3;
O for L2 | R | R | +| Traffic measurement | O c) | O c) | O c) | O c) | O c) | O c) | + +#### **(B) In case of hop-by-hop QoS guaranteed service** + +| Device | IP Terminal | Ethernet bridge | Separate type AGW | | | NT/ONT | +|-------------------------------|-----------------------|-----------------|-------------------|-----------------------|-----------------|-----------------| +| | | | (a) | (b) | (c) | | +| Device type (see clause 10.2) | (b) | (c) | (a) | (b) | (c) | (c) | +| Policing | N/A | O | O | O | O | O | +| Classification | R for L3;
O for L2 | R | R | R for L3;
O for L2 | R | R | +| Marking | O a) | O a) | O a) | O a) | O a) | O a) | +| Priority control | R for L3;
O for L2 | R | R | R for L3;
O for L2 | R | R | +| Bandwidth control | O b) | O b) | O b) | O b) | O b) | O b) | +| Traffic shaping | O b) | O b) | O b) | O b) | O b) | O b) | +| Admission control | N/A | N/A | N/A | N/A | N/A | N/A | +| Traffic measurement | O c) | O c) | O c) | O c) | O c) | O c) | + +R Recommended + +O Optional + +N/A Not Applicable + +a) If specific value in Ethernet MAC and/or IP header has to be overwritten, the support of this functional component is recommended. + +b) If transfer bandwidth has to be limited and/or surplus bandwidth has to be shared with already provisioned traffic flows, the support of these functional components is recommended. + +c) If traffic flows have to be measured for traffic management, the support of this functional component is recommended. This function should not affect user traffic flows. + +### 10.7 QoS control requirements for QoS service type 2 + +As a first step, this Recommendation discusses QoS control requirements focusing on QoS service type 2 (NGN release 1), as outlined in the previous clauses. The following requirement can be identified first. + +R10-1 AGW and NT/ONT should support L2 QoS control and/or L3 QoS control for NGN Release 1 services. Table 10-1 can be referred to for the required QoS control functional components for each device. + +At least L3 QoS control is required for offering L3 services. However, L3/L2 QoS mapping should be performed in L3F, in the case where L2 QoS control is provided. Therefore, the following requirements can be identified. + +R10-2: AGW should support L3 QoS control in the case where the network provides only L3 QoS control for NGN Release 1 services. + +R10-3: In the case where the network provides both L3 and L2 QoS control for NGN Release 1 services, AGW should support L3 and L2 QoS control including L3/L2 QoS mapping, while NT/ONT should support L2 QoS control. + +L2/L2 and/or L3/L3 QoS mapping should be performed in AGW when providing QoS guaranteed services to the IP terminal in NGN Release 1. As QoS guaranteed services are divided into end-to-end QoS guaranteed and hop-by-hop services, they are discussed separately as follows. + +Figure 10-5 shows an example for realizing hop-by-hop QoS guaranteed services. Note that WAN and LAN management planes may correspond to remote manager and local manager, respectively, which will be described in clause 11. Note that QoS mapping, such as mapping between LAN/WAN markings, is required in QoS control functional components other than admission control. The following scenario can be found: + +- LAN management plane sets proprietary LAN marking specifications onto AGW. +- After retrieving LAN marking specifications, WAN management plane sets the mapping between proprietary LAN and standardized WAN markings onto QoS control of AGW. +- QoS control components of IP terminal sends control messages containing proprietary marking #1. +- QoS control components of AGW maps the received marking #1 to the corresponding standardized marking #w in WAN and then sends control messages containing marking #w to WAN. + +![Diagram illustrating the realization of hop-by-hop QoS guaranteed services in QoS service type 2. It shows the interaction between an IP terminal, an AGW, and a WAN management plane. The IP terminal sends a proprietary marking #1 to the AGW. The LAN management plane sets proprietary LAN marking specifications onto the AGW. The WAN management plane retrieves LAN marking specifications and sets mapping between proprietary LAN and standardized WAN markings onto the AGW. The AGW then sends a standardized marking #w to the WAN management plane.](ea4fd10a9a501c602f2bea0f7f711877_img.jpg) + +The diagram illustrates the realization of hop-by-hop QoS guaranteed services. It features three main components: an IP terminal (green box), an AGW (orange box), and a WAN management plane (red box). The IP terminal contains a 'QoS control' component. The AGW contains a 'QoS control' component and is connected to both the IP terminal and the WAN management plane. The WAN management plane contains a 'QoS control' component. The diagram shows the following interactions: + +- The LAN management plane (part of the WAN management plane) sends a message to the AGW's QoS control component: "Set proprietary LAN marking specifications". +- The IP terminal's QoS control component sends a message to the AGW's QoS control component: "Proprietary marking #1". +- The WAN management plane's QoS control component sends a message to the AGW's QoS control component: "Retrieve LAN marking specifications" and "Set mapping between proprietary LAN and standardized WAN markings". +- The AGW's QoS control component sends a message to the WAN management plane's QoS control component: "Standardized marking #w". + +Legend: + +- Management plane (solid red line) +- Control plane (dashed black line) + +G.9971(10)\_F10-5 + +Diagram illustrating the realization of hop-by-hop QoS guaranteed services in QoS service type 2. It shows the interaction between an IP terminal, an AGW, and a WAN management plane. The IP terminal sends a proprietary marking #1 to the AGW. The LAN management plane sets proprietary LAN marking specifications onto the AGW. The WAN management plane retrieves LAN marking specifications and sets mapping between proprietary LAN and standardized WAN markings onto the AGW. The AGW then sends a standardized marking #w to the WAN management plane. + +**Figure 10-5 – A realization of hop-by-hop QoS guaranteed services in QoS service type 2** + +Figure 10-6 shows an example for realizing end-to-end QoS guaranteed services. Similar to hop-by-hop QoS service scenario, the mapping between proprietary LAN and standardized WAN markings is needed. Moreover, QoS mapping, such as mapping of LAN/WAN traffic descriptors and mapping of LAN/WAN markings, as well as QoS parameters are required in QoS control functional components, such as admission control, policing, bandwidth control and traffic shaping. The following scenario can be found. Note that the following scenario only describes the one other than marking mapping. + +- LAN management plane sets proprietary LAN traffic descriptor specifications onto AGW. +- After retrieving LAN traffic descriptor specifications, WAN management plane sets the mapping between proprietary LAN and standardized WAN traffic descriptors onto admission control of AGW. It also sets its QoS parameters. +- Admission control of the IP terminal sends control messages containing proprietary traffic descriptor #1. +- Admission control of AGW maps the received traffic descriptor #1 to the corresponding standardized traffic descriptor #w in WAN and then sends control messages containing traffic descriptor #w to WAN. + +![Diagram illustrating the realization of end-to-end QoS guaranteed services in QoS service type 2. It shows the interaction between LAN and WAN management planes, an IP terminal, an AGW, and a remote QoS control component.](5a1abd59a95fa47ae192807de151e9eb_img.jpg) + +The diagram illustrates the realization of end-to-end QoS guaranteed services in QoS service type 2. It features three main components: an IP terminal (green box), an AGW (orange box), and a remote QoS control component (green oval). Above the IP terminal and AGW are two management planes: the LAN management plane (red box) and the WAN management plane (red box). Solid red arrows represent the Management plane, and dashed black arrows represent the Control plane. + +**Management plane interactions:** + +- The LAN management plane sends proprietary LAN marking specifications and proprietary LAN traffic descriptor specifications to the AGW. +- The WAN management plane retrieves LAN marking specifications, sets the mapping between proprietary LAN and standardized WAN markings, retrieves LAN traffic descriptor specifications, sets the mapping between proprietary LAN and standardized WAN Traffic descriptors, and sets QoS parameters to the AGW. + +**Control plane interactions:** + +- The IP terminal's QoS control component sends Proprietary marking #1 and Proprietary traffic descriptor #1 to the AGW's QoS control component. +- The AGW's QoS control component sends Standardized marking #w and Standardized traffic descriptor #w to the remote QoS control component. + +Legend: + — Management plane (solid red line) + - - - Control plane (dashed black line) + +G.9971(10)\_F10-6 + +Diagram illustrating the realization of end-to-end QoS guaranteed services in QoS service type 2. It shows the interaction between LAN and WAN management planes, an IP terminal, an AGW, and a remote QoS control component. + +**Figure 10-6 – A realization of end-to-end QoS guaranteed services in QoS service type 2** + +# 11 Home network management + +## 11.1 Home network management architecture + +Clause 8.2 of [ITU-T G.9970] shows two kinds of management schemes by the remote management server (RMS). Scheme A is when RMS directly manages the home network end devices, such as the IP terminal, the non-IP GW and the non-IP terminal. On the other hand, Scheme B is when the RMS manages such devices through the AGW. Scheme A will be used when the IP terminal is supplied by the NSP in the future, while Scheme B will be used when some management protocols for the home network, such as UPnP, are used by the end users. Therefore, this Recommendation describes the requirements for home network management architecture focusing on Scheme B. Although Scheme B addresses the situation where AGW manages various kinds of home network end devices, this Recommendation analyses management of the IP terminal as well as the devices composing the IP home network, such as Ethernet bridge. This is shown in Figure 11-1. + +![Figure 11-1: Remote end device management configuration diagram. The diagram shows a flow from left to right: an 'IP terminal' (green box) connected to an 'IP home network' (orange rounded rectangle). The 'IP home network' is connected to an 'AGW' (green box). The 'AGW' is connected to an 'Access network' (blue rounded rectangle). Above the 'Access network' is a 'Remote management server (RMS)' (yellow box). Red arrows indicate management paths: from the RMS to the AGW, from the AGW to the IP home network, and from the IP home network to the IP terminal. A small text 'G.9971(10)_F11-1' is located at the bottom right of the diagram.](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg) + +Figure 11-1: Remote end device management configuration diagram. The diagram shows a flow from left to right: an 'IP terminal' (green box) connected to an 'IP home network' (orange rounded rectangle). The 'IP home network' is connected to an 'AGW' (green box). The 'AGW' is connected to an 'Access network' (blue rounded rectangle). Above the 'Access network' is a 'Remote management server (RMS)' (yellow box). Red arrows indicate management paths: from the RMS to the AGW, from the AGW to the IP home network, and from the IP home network to the IP terminal. A small text 'G.9971(10)\_F11-1' is located at the bottom right of the diagram. + +**Figure 11-1 – Remote end device management configuration** + +Scheme B has two kinds of management interfaces: one is the management interface between RMS and AGW, the other is the one between AGW and each device in the IP home network. Figure 11-2 shows the functional management architecture for Scheme B. Note that this figure shows the case of the NAT/NAPT aggregate type AGW with the bridge type LAN ports. The definition of each functional component can be described below: + +- Local agent (LA): According to the commands from the local manager, local L2 agent manages L2F of Ethernet bridge, while local L3 agent manages the IP terminal and the LAN-side parts of AGW. +- Local manager (LM): Management application functions for the IP home network, which interworks with the local agent. +- Remote agent (RA): According to the commands from the remote manager, it manages the WAN-side parts of the AGW. Moreover, it also interworks with the local manager in order to manage the IP home network. +- Remote manager (RM): Management application functions in the RMS, which interworks with the remote agent in the IP home network. + +This Recommendation assumes the following management applications for the local manager: + +- 1) Configuration management applications + - To show L3 (IP) network topology in the IP home network. + - To show L2 (Ethernet) network topology in the IP home network. + - To set, get and show the management information of each device in the IP home network. + - To upgrade the function of each device in the IP home network. + - To get specific information of each device in the IP home network, such as URLs for logging data. + - To reset or initialize each device in the IP home network. +- 2) Fault management applications + - To check whether the management interface is set up properly or not. + - To check whether each device in the IP home network is set up properly or not. +- 3) Performance management applications + - To check the network performance of the IP home network. + +Clause 11.2 describes the requirements for the RM-RA management interface, while clause 11.3 describes the requirements for the LM-LA management interface. Note that LM can reside in any device in the IP home network, although Figure 11-2 depicts the case where it resides in AGW. Moreover, there will be the case of only local M/A without remote M/A in order to manage the IP home network locally. + +![Figure 11-2: Functional management architecture for Scheme B. The diagram shows three main components: an IP terminal, an Ethernet bridge, and a NAT/NAPT aggregate type AGW with bridge type LAN ports. Above the AGW is an RMS (Remote manager) connected to a Remote agent. The Remote agent is connected to a Local management block, which in turn connects to Local L2 and L3 agents. The IP terminal contains a Local L3 agent and protocol blocks L3T, L3F, L2T, L2F, and L1T. The Ethernet bridge contains a Local L2 agent and protocol blocks L2F, L1T, and L1T. The AGW contains a Local L2 agent, a Local L3 agent, and protocol blocks L3T, L3F, L3T, L2F, L2T, L2F, and L1T. A red double-headed arrow indicates an external management interface between the Remote manager and the Remote agent. Blue dashed double-headed arrows indicate internal management interfaces between the Remote agent and Local management, and between Local management and the Local L2 and L3 agents. A red solid line connects the Local L3 agent in the IP terminal to the Local management block. A legend at the bottom defines the red double-headed arrow as an 'External management interface' and the blue dashed double-headed arrow as an 'Internal management interface'. The text 'G.9971(10)_F11-2' is in the bottom right corner.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg) + +Figure 11-2: Functional management architecture for Scheme B. The diagram shows three main components: an IP terminal, an Ethernet bridge, and a NAT/NAPT aggregate type AGW with bridge type LAN ports. Above the AGW is an RMS (Remote manager) connected to a Remote agent. The Remote agent is connected to a Local management block, which in turn connects to Local L2 and L3 agents. The IP terminal contains a Local L3 agent and protocol blocks L3T, L3F, L2T, L2F, and L1T. The Ethernet bridge contains a Local L2 agent and protocol blocks L2F, L1T, and L1T. The AGW contains a Local L2 agent, a Local L3 agent, and protocol blocks L3T, L3F, L3T, L2F, L2T, L2F, and L1T. A red double-headed arrow indicates an external management interface between the Remote manager and the Remote agent. Blue dashed double-headed arrows indicate internal management interfaces between the Remote agent and Local management, and between Local management and the Local L2 and L3 agents. A red solid line connects the Local L3 agent in the IP terminal to the Local management block. A legend at the bottom defines the red double-headed arrow as an 'External management interface' and the blue dashed double-headed arrow as an 'Internal management interface'. The text 'G.9971(10)\_F11-2' is in the bottom right corner. + +**Figure 11-2 – An example of functional management architecture for Scheme B** + +## 11.2 Requirements for RM-RA management interface + +Requirements for the management interface between RM and RA can be discussed from two aspects. One is the requirement for the management interface itself, while the other is the requirement for managing the WAN-side transport layer of the AGW. As this interface is already discussed in [BBF TR-069] and relevant documents, this Recommendation describes only the high-level requirements. + +The following requirements can be identified for the management interface: + +R11-R1: The standardized protocols should be used for the RM-RA management interface. [BBF TR-069] is recommended. + +R11-R2: IP address should be assigned to each RM and RA. + +R11-R3: It should be checked whether the RM-RA management interface protocol is set up properly or not, when needed. + +As shown in Figure 8-2, NAT/NAPT type AGW has L3T, while IP router type AGW does not have L3T. However, for the purpose of localizing the fault of the AGW WAN-side, IP address should be assigned to the WAN-side port of AGW. As described in clause 9, one has to keep in mind that there are several kinds of IP connection, such as native IPv4/v6, PPP, L2TP, etc. Therefore, the following requirements can be identified for managing transport layer of AGW. + +R11-R4: RA should notify RM of its managing IP address of the AGW WAN-side. Note that the IP address should be assigned to each IPv4/v6, PPP, L2TP connection at the AGW WAN-side. + +Moreover, as described at the end of clause 10, the following requirements can be identified for managing home network when providing NGN Release 1 services. + +R11-R5: RA should notify RM of its managing LAN traffic descriptors specifications in case of providing QoS guaranteed services to the IP terminal in the end-to-end QoS guaranteed services of NGN Release 1. + +R11-R6: RA should receive L2/L2 and/or L3/L3 QoS mapping, such as mapping between LAN/WAN traffic descriptors, as well as QoS parameters in case of providing QoS guaranteed services to the IP terminal in the end-to-end QoS guaranteed services of NGN Release 1. + +R11-R7: RA should notify RM of its managing marking specifications in case of providing QoS guaranteed services to the IP terminal in hop-by-hop QoS guaranteed services of NGN Release 1. + +R11-R8: RA should receive L2/L2 and/or L3/L3 QoS mapping, such as mapping between LAN/WAN marking in case of providing QoS guaranteed services to the IP terminal in hop-by-hop QoS guaranteed services of NGN Release 1. + +## **11.3 Requirements for LM-LA management interface** + +Requirements for the management interface between LM and LA can be discussed from two aspects. One is the requirement for management interface itself, while the other is the requirement for managing transport layer of the IP home network. + +The following requirements can be identified for the former: + +R11-L1: The standardized protocols should be used for the LM-LA management interface. The candidate protocols are ICMP, UPnP or LLDP. + +R11-L2: It should be checked whether the data link layer (Ethernet) between LM and local L2 agent, as well as the network layer (IP) between LM and Local L3 agent, is set up properly or not, when needed. + +As shown in Figure 8-2, NAT/NAPT type AGW has L3T, while IP router type AGW does not have L3T. However, for the purpose of localizing the fault of the AGW LAN-side, the IP address should be assigned to each LAN-side port of the AGW. Moreover, one must keep in mind that the IP address should be also assigned statically, although clause 9 is described in such a way that they are assigned automatically. Therefore, management requirements for the latter can be grouped into the following three categories. + +#### **1) Configuration management** + +R11-C1: Local L3 agent can notify LM of its managing IP address. + +R11-C2: Local L3 agent can notify LM of its managing MAC address. + +R11-C3: Local L2 agent can notify LM of its managing MAC forwarding table. + +R11-C4: Local L3 agent can notify LM of the management information of its managing device, such as the product class, the manufacturer's name, the device model name and the device model number. + +R11-C5: Local L2 agent can notify LM of the management information of its managing device, such as the product class, the manufacturer's name, the device model name and the device model number. + +R11-C6: Local L3 agent can perform the setting of the management information of its managing device based on the commands from LM, for example, when static IP address setting is needed for its managing device. + +R11-C7: Local L3 agent can send back the management information of its managing device based on the command from the LM. + +R11-C8: Local L3 agent can send back the URLs to log its managing device, based on the command from the LM. + +R11-C9: Local L3 agent can perform the reset or initialization of its managing device, based on the command from the LM. + +#### 2) Fault management + +R11-F1: Local L3 agent can notify the LM of the status of its managing device, periodically or when the device is in an abnormal state. + +R11-F2: Local L2 agent can notify the LM of the status of its managing device periodically or when the device is in an abnormal state. + +#### 3) Performance management + +R11-P1: Local L3 agent can send back the number of packets per port or flow etc., based on the command from the LM. + +# 12 Security management + +Although security management is categorized into authentication/authorization, encryption and defence, this Recommendation discusses requirements for encryption and defence relevant to home network transport layer 2 and 3. + +1) Encryption: The type of encryption and the key exchange protocol are relevant to this Recommendation. + +2) Defence: Packet filtering methods to prevent suspicious traffic from/to the AGW are relevant to this Recommendation. + +# Appendix I + +## Relationship among home network standards + +(This appendix does not form an integral part of this Recommendation) + +Figure I.1 shows which standardization bodies should be taken into account in order to study this Recommendation. As this Recommendation focuses on the architecture, QoS and management aspects of layer 2 and 3 in the home network, Broadband Forum, HGI, IEEE and UPnP are specifically the standardization bodies to coordinate with. + +![](4f148853ae68fdcf5e43f7604cab457d_img.jpg) + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------| +| Home Network System and Architecture
ITU-T, Broadband Forum, HGI | Middleware
OSGi | +| Transport protocol
IEEE 802.1 (802.1 AB, 802.1 AVB) | Terminal
UPnP, DLNA | +| Transmission technology
PLC: ITU-T, HPA, CEPCA, PUA, IEEE P1901
Phone line: ITU-T, Home PNA
Coaxial: ITU-T, CLINK/MoCA
Wireless: IEEE 802.11/WiFi
Ethernet: IEEE 802.3 | | + +**Figure I.1 – Major standardization bodies related to home network** + +Moreover, Figure I.2 shows the position of this Recommendation within ITU-T: + +- Layer 1 and layer 2 specifications of the home network are being studied in Study Group (SG) 9 and SG 15, while this Recommendation discusses the architecture and high-level requirements of layer 2 and 3 of the home network on the basis of [ITU-T G.9970]. As the layer 2 of this Recommendation focuses only on MAC bridge including VLAN, there is no overlap with other Recommendations, although some cooperation may be needed. +- As this Recommendation assumes only Ethernet for the access network, the relevant access network Recommendations are ITU-T G.983.x-series, etc. +- As this Recommendation handles QoS in transport layer, NGN and QoS Recommendations in SG 13 and in SG 12, respectively, are referred to. On the other hand, SG 16 is studying home network architecture as well as QoS in application layer. + +![Diagram showing the relationship among ITU-T SGs for home network. It illustrates the flow of data and control between various groups: SG12 (Application QoS/QoE), SG16 (Home network service and control), SG15 (Home network transport and physical layer), SG9 (IP cable and home networks), SG12 (Transport QoS), and SG13 (NGN).](692541e65db4dc852988ce77ebb60ce5_img.jpg) + +The diagram illustrates the relationship among ITU-T Study Groups (SGs) for a home network. It shows the flow of data and control between various groups: + +- SG12**: Application QoS/QoE, mainly on IPTV (e.g., ITU-T G.1010-G.1081) +- SG16**: Home network service and control (e.g., ITU-T H.622) +- SG15**: Home network transport (e.g., ITU-T G.9970, ITU-T G.9971) +- SG15**: Home network physical layer (e.g., ITU-T G.9960, ITU-T G.9954) +- SG9**: IP cable and home networks (e.g., ITU-T J.190) +- SG12**: Transport QoS (e.g., ITU-T Y.1540, Y.1541, Y.1563) +- SG13**: NGN (e.g., ITU-T Y.2111) +- SG15**: Access network (e.g., ITU-T G.983, G.984, G.985) + +Relationships are indicated by arrows: + +- A vertical double-headed orange arrow connects **SG16** and **SG15** (Home network transport). +- A vertical double-headed orange arrow connects **SG15** (Home network transport) and **SG15** (Home network physical layer). +- Horizontal double-headed orange arrows connect **SG15** (Home network transport) to **SG12** (Transport QoS) and **SG15** (Access network). +- A horizontal single-headed orange arrow points from **SG15** (Home network transport) to **SG13** (NGN). + +Diagram showing the relationship among ITU-T SGs for home network. It illustrates the flow of data and control between various groups: SG12 (Application QoS/QoE), SG16 (Home network service and control), SG15 (Home network transport and physical layer), SG9 (IP cable and home networks), SG12 (Transport QoS), and SG13 (NGN). + +G.9971(10)\_FI-2 + +**Figure I.2 – Relationship among ITU-T SGs for home network** + +## Bibliography + +- [b-BBF TR-124] Broadband Forum TR-124 (2006), *Functional Requirements for Broadband Residential Gateway Devices*, Version 1.0. +- [b-HGI] HGI (2008), *Home gateway technical requirement*, Version 1.0. +- [b-IEEE 802.1AB] IEEE Std. 802.1AB (2009), *Station and Media Access Control Connectivity Discovery*. +- [b-ISO/IEC 29341-1] ISO/IEC 29341-1:2008, *Information technology – UPnP Device Architecture – Part 1: UPnP Device Architecture*, Version 1.0. +- [b-ITU-T Y.1223] Recommendation ITU-T Y.1223 (2008), *Interworking guidelines for transporting assured IP flows*. +- [b-ITU-T Y.1540] Recommendation ITU-T Y.1540 (2007), *Internet protocol data communication service – IP packet transfer and availability performance parameters*. +- [b-ITU-T Y.2091] Recommendation ITU-T Y.2091 (2008), *Terms and definitions for next generation networks*. +- [b-ITU-T Y.2111] Recommendation ITU-T Y.2111 (2008), *Resource and admission control functions in next generation networks*. + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.998.2-201811-I_PDF-E/raw.md b/marked/G/T-REC-G.998.2-201811-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..0d97485b52995b6ef4b961e9c79b5ebe3880bbe5 --- /dev/null +++ b/marked/G/T-REC-G.998.2-201811-I_PDF-E/raw.md @@ -0,0 +1,1153 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.998.2** + +(11/2018) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Metallic access +networks + +# --- **Ethernet-based multi-pair bonding** + +Recommendation ITU-T G.998.2 + +## ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.998.2 + +# Ethernet-based multi-pair bonding + +## Summary + +Recommendation ITU-T G.998.2 describes a method for bonding of multiple digital subscriber lines (DSLs) for Ethernet transport. This Recommendation can support single-pair high-bit-rate digital subscriber line (SHDSL), very high-speed digital subscriber line (VDSL) and asymmetric digital subscriber line (ADSL) transport as well as future xDSL technologies as they emerge. + +This Recommendation builds on the IEEE 802.3ah-2004 methods and extends Ethernet transport over other xDSL technologies, including ADSL. The Recommendation does not describe the details of the specific xDSL transport technology, but rather, it focuses on the aspects of the physical coding sublayer (PCS) layer modifications required for bonding. + +This version of the Recommendation integrates all previous amendments and corrigenda with the 2005 version of ITU-T G.998.2. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.998.2 | 2005-01-13 | 15 | 11.1002/1000/7090 | +| 1.1 | ITU-T G.998.2 (2005) Amd. 1 | 2006-12-14 | 15 | 11.1002/1000/8996 | +| 1.2 | ITU-T G.998.2 (2005) Amd. 2 | 2007-12-07 | 15 | 11.1002/1000/9169 | +| 1.3 | ITU-T G.998.2 (2005) Amd. 3 | 2013-08-29 | 15 | 11.1002/1000/11998 | +| 1.4 | ITU-T G.998.2 (2005) Amd. 4 | 2015-08-29 | 15 | 11.1002/1000/12554 | +| 1.5 | ITU-T G.998.2 (2005) Cor. 1 | 2018-03-16 | 15 | 11.1002/1000/13537 | +| 2.0 | ITU-T G.998.2 | 2018-11-29 | 15 | 11.1002/1000/13753 | + +## Keywords + +Aggregation, bonding, DSL, encapsulation, Ethernet, IEEE 802.3ah. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-------------------------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 2 | +| 3.1 Terms defined elsewhere ..... | 2 | +| 3.2 Terms defined in this Recommendation ..... | 2 | +| 4 Abbreviations and acronyms ..... | 3 | +| 5 Technologies addressed and architecture ..... | 4 | +| 5.1 Technologies nomenclature ..... | 5 | +| 5.2 System considerations ..... | 5 | +| 5.3 Relationship between IEEE 802.3ah-2004 terminology and layering
(informative)..... | 5 | +| 5.4 Multiple bearers..... | 7 | +| 6 Exceptions to clause 61 of IEEE 802.3ah-2004 ..... | 7 | +| 6.1 Exceptions to clause 61.1 of 802.3ah-2004..... | 7 | +| 6.2 Exceptions to clause 61.2 of 802.3ah-2004..... | 8 | +| 6.3 Exceptions to clause 61.3 of 802.3ah-2004..... | 10 | +| 7 Management ..... | 11 | +| 8 Handshake..... | 11 | +| 9 Intentional temporary shutdown of some bonded lines ..... | 12 | +| Annex A – Ethernet bonding with 64/65-octet encapsulation ..... | 13 | +| Annex B – Ethernet bonding with HDLC encapsulation..... | 14 | +| Annex C – Frame-based protocol for discovery/aggregation and link management..... | 15 | +| C.1 Bonding control architecture ..... | 15 | +| C.2 Operational overview of bonding aggregation control protocol ..... | 16 | +| C.3 Protocol operation ..... | 19 | +| C.4 Bonding aggregation control protocol frame formats ..... | 26 | +| Annex D – Ethernet bonding with DTU encapsulation ..... | 30 | +| Bibliography..... | 31 | + + + +## Recommendation ITU-T G.998.2 + +# Ethernet-based multi-pair bonding + +# 1 Scope + +This Recommendation specifies portions of clause 61 of [IEEE 802.3ah]-2004 amendment to carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specification as a normative reference and identifies the requirements for multi-pair bonding in [IEEE 802.3ah]-2004 that are different in the United States. Further, this Recommendation specifies the requirements for extending the bonding methods in [IEEE 802.3ah]-2004 to xDSL technologies other than very high-speed digital subscriber line (VDSL) and single-pair high-bit-rate digital subscriber line (SHDSL). + +This Recommendation has the following four objectives: + +- 1) provide support for operation of xDSL technologies on multiple pairs of voice-grade twisted pair cable; +- 2) provide 100 Mbit/s burst data rate at the Ethernet media independent interface using rate matching; +- 3) provide full duplex operation; +- 4) provide a communication channel with a mean bit error rate (BER) at the $\alpha/\beta$ service interface of less than $10^{-7}$ . + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.991.2] Recommendation ITU-T G.991.2 (2003), *Single-pair high-speed digital subscriber line (SHDSL) transceivers*. +- [ITU-T G.992.1] Recommendation ITU-T G.992.1 (1999), *Asymmetric digital subscriber line (ADSL) transceivers*. +- [ITU-T G.992.3] Recommendation ITU-T G.992.3 (2009), *Asymmetric digital subscriber line transceivers 2 (ADSL2)*. +- [ITU-T G.992.5] Recommendation ITU-T G.992.5 (2009), *Asymmetric digital subscriber line transceivers 2 (ADSL2) – Extended bandwidth ADSL2 (ADSL2plus)*. +- [ITU-T G.993.1] Recommendation ITU-T G.993.1 (2004), *Very high speed digital subscriber line transceivers (VDSL)*. +- [ITU-T G.993.2] Recommendation ITU-T G.993.2 (2015), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [ITU-T G.994.1] Recommendation ITU-T G.994.1 (2017), *Handshake procedures for digital subscriber line transceivers*. + +- [ATIS T1.424] T1.424\* (2004), *Interface between Networks and Customer Installation – Very-high-bit-rate Digital Subscriber Lines (VDSL) Metallic Interface (DMT-Based)*. +- [IEEE 802.3-2002] IEEE 802.3-2002, *IEEE Standard for IT – Telecommunications and Information Exchange Between Systems – LAN/MAN – Specific Requirements – Part 3: CSMA/CD Access Method and Physical Layer Specifications*. +- [IEEE 802.3-2005] IEEE 802.3-2005, *IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications*. +- [IEEE 802.3ah] IEEE 802.3ah-2004, *IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specification – Amendment: Media Access Control Parameters, Physical Layers, and Management Parameters for Subscriber Access Networks*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +None. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following terms: + +**3.2.1 10PASS-TS:** The IEEE 802.3 standard for delivering single and multi-pair Ethernet transport over ITU-T G.993.1 (MCM) transceivers. + +**3.2.2 2BASE-TL:** The IEEE 802.3 standard for delivering single and multi-pair Ethernet transport over ITU-T G.991.2 transceivers. + +**3.2.3 aggregation group:** A collection of lines that may be aggregated into a single Ethernet interface. + +**3.2.4 carrier sense:** In a local area network, an ongoing activity of a data station to detect whether another station is transmitting. + +NOTE – The carrier sense signal indicates that one or more DTEs are currently transmitting. + +**3.2.5 collision:** A condition that results from concurrent transmissions from multiple data terminal equipment (DTE) sources within a single collision domain. + +**3.2.6 downstream:** Direction from central office to remote terminal. + +**3.2.7 media independent interface:** In IEEE 802.3, a transparent signal interface at the bottom of the Reconciliation sublayer. + +**3.2.8 physical medium attachment:** That portion of the physical layer that contains the functions for transmission, reception collision detection, clock recovery and skew alignment. + +--- + +\* T1 standards are maintained since November 2003 by ATIS. + +**3.2.9 physical medium dependent:** That portion of the physical layer responsible for interfacing to the transmission medium. The physical medium dependent (PMD) is located just above the medium dependent interface (MDI). + +**3.2.10 physical media entity:** In IEEE 802.3-2005, a reference to an individual transceiver contained within an aggregate group where a transceiver carries only one packet stream. This Recommendation also supports operation over transceivers carrying multiple (at gamma interface logically separated) packet streams. In this Recommendation, a physical media entity (PME) is a reference to one logical channel out of a set of one or more channels on the same individual transceiver. Each such PME carries a single packet stream and is contained within one aggregate group. + +NOTE 1 – In case preemption is used on a bearer channel, two PMEs each reference one of the two logical channels on the same bearer channel. In case pre-emption is not used on a bearer channel, a PME defaults to a reference to the one bearer channel. + +NOTE 2 – Although such a PME cannot be physically isolated within a transceiver carrying multiple packet streams, the naming PME is maintained for consistency with IEEE 802.3-2005 and for consistency in case the transceiver carries only one packet stream. + +**3.2.11 remote terminal:** A terminal located downstream from a central office switching system. + +**3.2.12 upstream:** Direction from remote terminal to central office. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations: + +| | | +|----------|------------------------------------------------------------| +| $\alpha$ | the interface between the PMS-TC and TPS-TC layers at a CO | +| $\beta$ | the interface between the PMS-TC and TPS-TC layers in CPE | +| $\gamma$ | the interface between the TPS-TC layer and the PCS layer | +| ADSL | Asymmetric Digital Subscriber Line | +| ANSI | American National Standards Institute | +| ATIS | Alliance for Telecommunications Industry Solutions | +| BACP | Bonding Allocation Control Protocol | +| BACPDU | BACP Data Unit | +| BCE | Bonding Control Engine | +| BER | Bit Error Rate | +| CL | Capabilities List | +| CLR | Capabilities List Request | +| CO | Central Office | +| CPE | Customer Premises Equipment | +| CRC | Cyclic Redundancy Check | +| CS | Carrier Sense | +| CSMA/CD | Carrier Sense Multiple Access/Collision Detection | +| DSL | Digital Subscriber Line | +| DSLAM | DSL Access Multiplexer | +| DTE | Data Terminal Equipment | + +| | | +|--------|-----------------------------------------------------------------------------| +| DTU | Data Transfer Unit | +| EFM | Ethernet in the First Mile | +| EMS | Element Management System | +| FEC | Forward Error Correction | +| FIFO | First In, First Out | +| GID | Group ID | +| HDLC | High-level Data Link Control | +| MAC | Media Access Control | +| MCM | Multi-Carrier Modulation | +| MII | Medium Independent Interface | +| MP | Mode Proposal | +| MS | Mode Select | +| MSB | Most Significant Bit | +| OAM | Operations, Administration, and Maintenance | +| PAF | PMA Aggregation Function | +| PCS | Physical Coding Sublayer | +| PHY | Physical Layer Entity Sublayer | +| PMA | Physical Medium Attachment | +| PMD | Physical Medium Dependent | +| PME | Physical Media Entity | +| PMS-TC | Physical Media-Specific TC Layer | +| PTM | Packet Transfer Mode | +| SFD | Start Frame Delimiter | +| SHDSL | Single-Pair High-bit-rate DSL | +| TC | Transmission Convergence layer | +| TC-CRC | Transmission Convergence – Cyclic Redundancy Check | +| TLV | Type Length Value | +| TPS-TC | Transmission Protocol-Specific TC Layer | +| VDSL | Very High-speed Digital Subscriber Line | +| xDSL | a collective term referring to any of the various types of DSL technologies | + +# 5 Technologies addressed and architecture + +This clause addresses technology specific parameters for some bonded physical layer entity sublayers (PHYs). The values presented here were derived from the rules set forth in clause 61 of [IEEE 802.3ah]-2004. Other PHYs may be addressed by following these rules. + +## 5.1 Technologies nomenclature + +Large portions of this Recommendation reference the IEEE 802.3ah-2004 specification. A cross-reference to the technology nomenclature, and a reference to the relevant standards, are given in Table 1. + +**Table 1 – Technology nomenclature** + +| Reference in this Recommendation | IEEE 802.3ah-2004 reference | Relevant standard | +|----------------------------------|-----------------------------|-------------------| +| VDSL | 10PASS-TS | [ATIS T1.424] | +| SHDSL | 2BASE-TL | [ITU-T G.991.2] | +| ADSL | N/A | [ITU-T G.992.1] | + +As shown in Table 1, the IEEE reference to 10PASS-TS is the IEEE 802.3 standard for transporting Ethernet using a multi-carrier modulation (MCM)-VDSL-based PHY. Likewise, 2BASE-TL is the IEEE 802.3 standard for transporting Ethernet using an SHDSL-based PHY. There is no IEEE standard for transporting Ethernet over asymmetric digital subscriber line (ADSL), though that operation is clarified in this Recommendation. + +## 5.2 System considerations + +The copper PHYs addressed by this Recommendation are only defined for full duplex operation as defined in the IEEE 802.3 specification. + +## 5.3 Relationship between IEEE 802.3ah-2004 terminology and layering (informative) + +The physical coding sublayer (PCS) contains two functions: media access control (MAC)-PHY rate matching and physical media entity (PME) aggregation. The functional position of the PCS is shown in Figure 1. + +The $\gamma$ -interface and the $\alpha(\beta)$ -interface are generic interfaces used in various digital subscriber line (xDSL) specifications such as the ones referenced in clause 2. The $\alpha(\beta)$ -interface is a simple octet-synchronous data interface; the $\gamma$ -interface add protocol-awareness. + +For physical medium dependent (PMD), the bit rates in the shaded area labelled "PMD rate domain" are derived from the DSL bit rates. Data is transferred across the $\gamma$ -interface at the rate imposed by the lower layers. The bit rates in the shaded area labelled "100 Mbit/s rate domain" are synchronous to the medium independent interface (MII) rate. Data is transferred across the MII at the rate of one nibble per MII clock cycle. The MAC-PHY rate matching function adjusts the inter-packet gap so that the net data rate across this interface matches the sum of rates across the $\gamma$ -interface.1 + +In the transmit direction, frames are transferred from the MAC to the PCS across the MII when the MAC-PHY rate matching function allows this. In the PCS, preamble and start frame delimiter (SFD) octets are removed. The data frame is fragmented by the physical medium attachment (PMA) aggregation function (PAF), and fragments are forwarded, optionally through a flexible cross-connect, towards each of the aggregated PME instances via the $\gamma$ -interface. The transmission convergence layer (TC) accepts data from the MAC-PHY rate matching function or the PAF, at the rate at which it can be processed by the TC sublayer, by asserting Tx-Enbl on the $\gamma$ -interface. + +The optional flexible cross-connect function may be present to provide access from a centralized bonding function (PAF) to TCs on lines distributed throughout a system. The method by which frames + +--- + +1 Bit domains and physical clock domains do not necessarily coincide. The TC sublayer receives as clock signal from the PMA via the $\alpha(\beta)$ -interface, and a clock signal from the optional PAF or the MAC-PHY Rate Matching function via the $\gamma$ -interface. The TC provides matching between the two clock domains. + +are transferred between the bonding function and the various TCs in the bonded group is outside the scope of this Recommendation. + +In the receiver direction the TC sublayer pushed data to the PAF (if present) or the MAC-PHY rate matching function by asserting Rx\_Enbl on the $\gamma$ -interface. The PAF reassembles the received fragments into data frames. Preamble and SFD octets are generated and prepended to the data frame prior to passing it up to the MAC across the MII. The MAC-PHY rate matching function may delay the transfer of the frame to avoid simultaneous transfer of transmit and receive frames if required. + +![Figure 1 – Overview of PCS functions. The diagram illustrates the protocol stack for a 100 Mbit/s domain and multiple optional additional TC clients. The stack is divided into three main sections: TC Client, Flexible Cross-Connect (optional), and PME. The TC Client section includes MAC, MII (Optional), PCS, MAC-PHY Rate Matching, and PME Aggregation (Optional). The Flexible Cross-Connect section connects the TC Client to the PME. The PME section includes TC (Packet encapsulation), PMA, and PMD. The diagram shows three parallel stacks for the TC Client and PME, connected by the Flexible Cross-Connect. The leftmost stack is labeled '100 Mbit/s domain' and the rightmost stacks are labeled 'Up to 31 optional additional TC clients (blocks above γ-interface)' and 'Up to 31 optional additional PME instances'. The interfaces between the TC Client and PME are labeled γ and α(β).](042733dc5e8e7f5f30b60adba3266cde_img.jpg) + +Figure 1 – Overview of PCS functions. The diagram illustrates the protocol stack for a 100 Mbit/s domain and multiple optional additional TC clients. The stack is divided into three main sections: TC Client, Flexible Cross-Connect (optional), and PME. The TC Client section includes MAC, MII (Optional), PCS, MAC-PHY Rate Matching, and PME Aggregation (Optional). The Flexible Cross-Connect section connects the TC Client to the PME. The PME section includes TC (Packet encapsulation), PMA, and PMD. The diagram shows three parallel stacks for the TC Client and PME, connected by the Flexible Cross-Connect. The leftmost stack is labeled '100 Mbit/s domain' and the rightmost stacks are labeled 'Up to 31 optional additional TC clients (blocks above γ-interface)' and 'Up to 31 optional additional PME instances'. The interfaces between the TC Client and PME are labeled γ and α(β). + +G.998.2\_F01 + +**Figure 1 – Overview of PCS functions** + +Figure 2 compares the ITU layering with the IEEE layering by showing the relative positions of the $\gamma$ and $\alpha(\beta)$ interfaces and the relevant architectural blocks. Some things to note include: + +- 1) In [IEEE 802.3ah]-2004, the entire function of a bonded group (taking in/out frames, fragmenting/reassembly across multiple lines, encapsulating fragments on a line, etc.) is referred to as the PCS function. In Figure 2, two lines are shown being aggregated into the leftmost PAF function in both protocol stacks. +- 2) Since [IEEE 802.3ah]-2004 has only a single TPS-TC (it defines only 64/65-octet encapsulation as the TPS-TC), the TPS-TC function is abbreviated TC. +- 3) [IEEE 802.3ah]-2004 requires a rate matching function to provide an interface between the well-defined 100 Mbit/s Ethernet MAC and the variable rate aggregation function. The ITU protocol stack does not require the use of the standard Ethernet MAC, and thus, no rate matching function is required. + +As shown in the diagram, the protocol stacks are very similar, but have terminology and architectural differences related to the historical terminology and architecture of the individual standards organization. + +![Figure 2 – Comparison of IEEE and ITU protocol stacks. The diagram shows two side-by-side protocol stacks. The left stack is labeled 'IEEE protocol stack' and consists of two parallel vertical columns. Each column has a box for 'Ethernet', followed by '802.3 MAC', 'Rate matching', and 'PAF'. Below the PAF boxes is a box labeled 'Optional cross-connect'. Below this are 'TC', 'PMA', and 'PMD' boxes. The right stack is labeled 'ITU protocol stack' and also has two parallel vertical columns. Each column has a box for 'Ethernet', followed by a note: 'Note that a rate matching algorithm may be implemented somewhere above the PAF - the IEEE rate matching algorithm is specifically designed for the Ethernet MAC'. Below the note is a 'PAF' box, then an 'Optional cross-connect' box, then 'TPS-TC', 'PMS-TC', and 'PMD' boxes. A dashed box labeled 'Bonded group' encloses the bottom three layers of both columns. Between the two stacks, there are labels 'Frames' and 'Fragments' with dashed lines pointing to the Ethernet and PAF layers respectively. There are also labels 'γ' and 'α(β)' with dashed lines pointing to the TC and PMA layers respectively. The text 'G.998.2_F02' is at the bottom right.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Figure 2 – Comparison of IEEE and ITU protocol stacks. The diagram shows two side-by-side protocol stacks. The left stack is labeled 'IEEE protocol stack' and consists of two parallel vertical columns. Each column has a box for 'Ethernet', followed by '802.3 MAC', 'Rate matching', and 'PAF'. Below the PAF boxes is a box labeled 'Optional cross-connect'. Below this are 'TC', 'PMA', and 'PMD' boxes. The right stack is labeled 'ITU protocol stack' and also has two parallel vertical columns. Each column has a box for 'Ethernet', followed by a note: 'Note that a rate matching algorithm may be implemented somewhere above the PAF - the IEEE rate matching algorithm is specifically designed for the Ethernet MAC'. Below the note is a 'PAF' box, then an 'Optional cross-connect' box, then 'TPS-TC', 'PMS-TC', and 'PMD' boxes. A dashed box labeled 'Bonded group' encloses the bottom three layers of both columns. Between the two stacks, there are labels 'Frames' and 'Fragments' with dashed lines pointing to the Ethernet and PAF layers respectively. There are also labels 'γ' and 'α(β)' with dashed lines pointing to the TC and PMA layers respectively. The text 'G.998.2\_F02' is at the bottom right. + +**Figure 2 – Comparison of IEEE and ITU protocol stacks** + +## 5.4 Multiple bearers + +For physical layers that support multiple bearers, the methods of this Recommendation can be applied to one or multiples of those bearers independently. As each bearer can independently carry individual fragments, multiple bearers can be aggregated across multiple lines. Multiple bearers on the same line should not be aggregated. + +# 6 Exceptions to clause 61 of IEEE 802.3ah-2004 + +xDSL systems bonding Ethernet TPS-TCs, in accordance with this Recommendation, shall comply with clause 61 of [IEEE 802.3ah]-2004, except as specifically detailed in the remainder of the clause. + +This clause details the exceptions to clauses 61.1 and 61.2 of [IEEE 802.3ah]-2004, for generalizing the Ethernet bonding function, known as the PAF in [IEEE 802.3ah]-2004, to xDSL technologies beyond SHDSL ([ITU-T G.991.2], 2BASE-TL) and VDSL ([ITU-T G.993.1], 10PASS-TS). + +This Recommendation does not specify the TC used for bonding. Clause 61.2 of [IEEE 802.3ah]-2004 defines a TC based on 64/65-octet encapsulation. However, other packet transfer mode (PTM) TCs are also supported by this Recommendation. + +Clauses 61.5 through 61.10 are not applicable to this Recommendation. + +## 6.1 Exceptions to clause 61.1 of 802.3ah-2004 + +Clause 61.1 provides an introduction and overview of the rest of clause 61. There is a general exception throughout clause 61.1 in that this Recommendation expands the scope of clause 61 beyond 10PASS-TS (VDSL) and 2BASE-TL (SHDSL). Throughout the descriptive text in clause 61.1.1, it should be noted that the specific references to 10PASS-TS and 2BASE-TL can be replaced with more generic references to multi-pair and physical layer systems as defined in this Recommendation. + +### 6.1.1 Exceptions to clause 61.1.1 of 802.3ah-2004 + +Clause 61.1.1 applies with the previously noted generalization. + +### 6.1.2 Exceptions to clause 61.1.2 of 802.3ah-2004 + +Clause 61.1.2 lists the objectives of Ethernet bonding as defined by [IEEE 802.3ah]-2004. This Recommendation includes the following added objective. + +- g) Operation of Ethernet multi-pair aggregation over xDSL technologies including ADSL, and future xDSL technologies. + +### **6.1.3 Exceptions to clause 61.1.3 of 802.3ah-2004** + +Clause 61.1.3 compares the IEEE 802.3 architecture to the traditional xDSL architecture and applies as is. + +### **6.1.4 Exceptions to clause 61.1.4 of 802.3ah-2004** + +Clause 61.1.4 overviews the entirety of clause 61. Only those clauses relevant to multi-pair operation are relevant to this Recommendation. The relevant clauses are 61.1.4.1.1 and 61.1.4.1.3. The other clauses of 61.1.4 are not relevant to this Recommendation. + +### **6.1.5 Exceptions to clause 61.1.5 of 802.3ah-2004** + +Clause 61.1.5 provides examples of multi-pair Ethernet configurations. Although the examples use hardware registers specific to [IEEE 802.3ah], the multi-pair bonding examples and possibilities are general to this Recommendation as well. + +## **6.2 Exceptions to clause 61.2 of 802.3ah-2004** + +This clause details the exceptions to clause 61.2 of [IEEE 802.3ah]. + +### **6.2.1 Exceptions to clause 61.2.1 of 802.3ah-2004** + +Clause 61.2.1 defines rate-matching procedures Ethernet-over-xDSL technologies when utilizing an existing Ethernet media access control. This clause is unchanged and is applicable whenever the system is using an IEEE 802.3-compliant MAC over an Ethernet bonding and/or TPS-TC technology as defined in this Recommendation. + +### **6.2.2 Exceptions to clause 61.2.2 of 802.3ah-2004** + +Clause 61.2.2 describes the PME aggregation function (PAF) which performs the multi-pair aggregation function for Ethernet-over-xDSL technologies. The PAF is responsible for segmenting a frame as received from the higher layer into multiple fragments, and transmitting them to the TPS-TCs on the individual loops. It is likewise responsible for reassembling fragments, as received from the TPS-TCs on the individual loops, into frames and handing them to the higher layer. + +The PAF is an optional layer in IEEE 802.3. When not implemented, or when the PAF function is disabled, there can be at most one pair in an aggregate, and the frames pass between the higher layer and the TPS-TC directly. + +The primary exceptions to clause 61.2.2, when generalizing the Ethernet transport methods of [IEEE 802.3ah], are in the control mechanisms for provisioning and discovering which pairs are in the same aggregate group. + +Clause 61.2.2.8.3 describes a set of registers for controlling the pairs in an aggregate group. These registers are: + +- 1) Capability register. Used so that a management or control entity may read from the physical layer whether multi-pair operation is supported, and if it is, whether it is enabled. +- 2) PMI\_Available\_register. Used to indicate what loops could be placed in an aggregate group. +- 3) PMI\_Aggregate\_register. Used to indicate what loops are in what aggregate groups. +- 4) Remote\_discovery\_register. Used to automatically discovery what loops are connected to the same remote device. +- 5) Aggregation\_link\_state\_register. Used to indicate link state to the aggregation and management layer. + +The underlying support for these registers is provided by [ITU-T G.994.1] handshaking messages. The mapping of these register settings to [ITU-T G.994.1] handshaking mechanisms is explained in clause 61.4 of [IEEE 802.3ah], specifically for VDSL-based and SHDSL-based PHYs. Both this + +Recommendation and the IEEE 802.3ah-2004 standard utilize handshake codepoints defined in [ITU-T G.994.1]. Clause 8 of this Recommendation supplies more information on using handshake to determine aggregation groups. + +The network side uses the PME\_ID of each link in the bonding group to retrieve management data through Ethernet operations, administration, and maintenance (OAM) (clause 30/57 of [IEEE 802.3-2002]). Each [ITU-T G.994.1] capabilities list request (CLR) message shall include the 48-bit remote discovery register and the 32-bit PME aggregate register. The network side may derive the PME\_IDs of each of the links in the bonding group by adding the links one-by-one to the bonding group during PME aggregation, and observing the change in the PME aggregate register with each addition. However, to allow parallel initialization of the links in the bonding group and, hence, to allow shortening of the bonding group initialization time, the remote side should also include the 5-bit PME\_ID in each CLR message. Corresponding ITU-T G.994.1 codepoints are defined for the PME\_ID as a supplement to clause 61 of [IEEE 802.3-2002]. + +### 6.2.3 Exceptions to clause 61.2.2.5 + +Clause 61.2.2.5 of [IEEE 802.3-2005] requires the receiving PCS to be able to handle a maxDifferentialDelay of 15000-bit times between the slowest link (i.e., link with the lowest net data rate) and the fastest link (i.e., link with the highest net data rate) in an N-pair bonding group. This allows to operate at a slowest link fragment size value (max. 512 octets) and at a fastest link speed value (max. $400/(N+3)$ Mbit/s) and at a speed ratio value (fastest to slowest net data rate ratio, max. 4:1), all close to their maximum allowed values, with the transmitting PCS assuring that: + +$$(8 \times \text{slowest\_link\_fragment\_size}) \times (\text{speed\_ratio}) \leq 15000$$ + +and in case the transceiver jitter does not significantly contribute to the differential delay to be handled by the receiving PCS. A low transceiver jitter is particularly achieved by [ITU-T G.992.1] (SHDSL) transceivers. + +However, in the case of ADSL2plus and VDSL2, transceiver jitter is caused e.g., by buffering inside the transmitting or receiving transceiver (number of octets jitter), by symbol rate (1 symbol jitter = 250 $\mu\text{s}$ ), by sync symbols (1 symbol jitter = 250 $\mu\text{s}$ ), and by forward error correction (FEC) ( $K_{\text{FEC}}$ octets jitter). Transceiver jitter is further increased by differences over the transceivers in the bonding group in interleaving delay (number of $\mu\text{s}$ jitter) and processing time (number of $\mu\text{s}$ jitter). + +While [ITU-T G.992.3], [ITU-T G.992.5] and [ITU-T G.993.2] provide means to reduce the interleaving delay difference over the links in the bonding group down to some low value depending on granularity, these Recommendations do not define transceiver jitter bounds. The remaining transceiver jitter can be estimated as an additional differential delay (in bit times) at the receiving PCS up to about: + +$$(K_{\text{FEC}} \times 8 / \text{slowest\_link\_net\_data\_rate} + 500 \mu\text{s}) \times \text{fastest\_link\_net\_data\_rate}$$ + +depending on whether or not the transceiver jitter is reduced by the receiving transceiver. + +If such differential delay is input to a receiving PCS capable of handling only 15000-bit times of differential delay, then the net data rate of each link in the bonding group is limited between 0 and 25 Mbit/s, depending on the transmitting PCS's choice of maximum or minimum fragment size and speed ratio, respectively. To avoid such limitations on the net data rate of ADSL2plus or VDSL2 links, the receiving PCS should be able to handle the additional differential delay introduced by the transceiver jitter. + +NOTE – For example, to support the full 100 Mbit/s aggregate net data rate for a 2-pair bonding group at a 4:1 speed ratio, the receiving PCS may need to be able to handle a total differential delay of approximately 65000-bit times, in case the receiving transceiver does not reduce the transceiver jitter. + +## 6.3 Exceptions to clause 61.3 of 802.3ah-2004 + +Clause 61.3 of [IEEE 802.3ah] defines 64/65-octet encapsulation, which is the required TPS-TC for Ethernet bonding as defined in [IEEE 802.3ah]. However, this Recommendation does not define a specific TPS-TC required for the Ethernet bonding function. Therefore, clause 61.3 is not required for this Recommendation. + +The operation of Ethernet bonding over two possible packet TPS-TCs is given in separate annexes – Annex A for 64/65-octet encapsulation, and Annex B for high-level data link control (HDLC) encapsulation. 64/65-octet encapsulation is the preferred packet TPS-TC for Ethernet bonding. + +Although the TPS-TC for Ethernet bonding is not specified in this Recommendation, there are requirements on whatever packet TPS-TC is used for this bonding Recommendation. Multi-pair operation requires a bound on the differential latency experienced between pairs in an aggregated group. The encapsulation method chosen for a specific implementation shall result in traffic over the $\gamma$ -interface meeting the restrictions of clauses 61.2.2.5 and 61.2.2.6. + +The functional model of packet data transport is presented in Figure 3. In the transmit direction, the PTM entity obtains data packets to be transported from the application interface. The PTM entity processes each packet and applies it in a byte format to the $\gamma$ -interface. The TPS-TC (PTM-TC) receives the packet from the $\gamma$ -interface, encapsulates it into a special frame (PTM-TC frame) and maps into the physical media-specific TC layer (PMS-TC) frame (transmission frame) for transmission over the physical connection. + +In the receive direction, the PTM-TC frame extracted from the received PMS-TC frame is directed into the PTM-TC. The PTM-TC recovers the transported packet and delivers it to the PTM entity via the $\gamma$ -interface. + +The PTM path-related OAM data, including information on errored packets, shall be presented to the TPS-TC management entity providing all necessary OAM functions to support the PTM-TC. + +![Functional model of PTM transport diagram](cb4cfa42ce34febde7bdb882f3fc3094_img.jpg) + +The diagram illustrates the functional model of PTM transport. It shows three main components: PTM-entity, PTM-TC, and TPS-TC management. The PTM-entity is at the top, connected to the PTM-TC via the $\gamma$ -interface (indicated by a dashed line). The PTM-TC is connected to the PMS-TC at the bottom via the $\alpha(\beta)$ -Interface (another dashed line). The TPS-TC management is connected to the PTM-TC and also to the OAM and PMS-TC & PMD components. A vertical double-headed arrow on the left indicates the TPS-TC sublayer. The diagram is labeled G.998.2\_F03. + +Functional model of PTM transport diagram + +**Figure 3 – Functional model of PTM transport** + +In the transmit direction, the TPS-TC sublayer accepts data from the PTM Entity at the rate at which it can be processed by the TPS-TC sublayer, by asserting Tx-Enbl on the $\gamma$ -interface. In the receiver direction, the TC sublayer pushes data to the PTM Entity by asserting Rx\_Enbl on the $\gamma$ -interface. + +For Ethernet bonding, the PTM entity is the PAF (PME aggregation function). + +# 7 Management + +Management is an optional layer in IEEE 802.3 Ethernet, and is therefore an optional layer in Ethernet bonding. However, when a management layer is present, the following attributes are recommended for each bonded Ethernet port: + +- Local aggregation capacity. The number of lines that may be aggregated by the bonding layer. +- Local lines available. The set of lines that may be put into this aggregate. Note that a line may appear to be potentially available to more than one aggregate port. +- Local lines aggregated. The set of lines that are currently in this aggregate. A line may be in at most one aggregate at a time. +- Local aggregate bandwidth. The current bandwidth of the aggregate Ethernet port (sum of the transmit data rates of the individual lines in the aggregate). + +The following attributes are additionally recommended for the STU-C, and reflect (at the STU-C) the above attributes of the STU-R. + +- Remote aggregation capacity. The number of lines that may be aggregated by the bonding layer at the peer port of the STU-R. +- Remote lines available. The set of lines that may be put into this aggregate at the peer port of the STU-R. Note that a line may appear to be potentially available to more than one aggregate port. +- Remote lines aggregated. The set of lines that are currently in this aggregate at the peer port of the STU-R. A line may be in at most one aggregate at a time. +- Remote aggregate bandwidth. The current bandwidth of the aggregate Ethernet port (sum of the transmit data rates of the individual lines in the aggregate) at the peer port of the STU-R. This is equivalent to the sum of the receive data rates at the STU-C. + +These management parameters echo those defined for the aggregation entity of [IEEE 802.3ah]-2004 (See clause 30.11 of [IEEE 802.3ah]). + +# 8 Handshake + +Clause 61.4 of [IEEE 802.3-2005] defines the handshake operation for the IEEE standards 2BASE-TL and 10PASS-TS. That clause defines handshake procedures for discovering which pairs are provisioned in which aggregate groups using the PME aggregation and PME aggregation discovery codepoints of the IEEE handshake tree. + +The procedures of that clause are followed in this Ethernet bonding Recommendation with the following exceptions: + +- There is no "PAF enable" parameter as described in clause 61.4 of [IEEE 802.3-2005]. That parameter is used to define whether bonding is performed. As this Recommendation references bonded operation only, that parameter is not required. +- The "PME identification" Spar(2) bit indicates that PME identification is included in the CLR message. The corresponding Npar(3) field contains the five-bit value (0 to 31) of the PME ID. +- The "BACP support" NPar(2) bit indicates support for the bonding allocation control protocol (BACP) protocol specified in Annex C. If this bit is set to ZERO in the CLR or capabilities list (CL) message, then the bit shall also be set to ZERO in the mode select (MS) message. If this bit is set to ONE in both the CLR and CL message, then this bit shall also be set to ONE in the MS message. +- Table 2 describes the meaning of the "BACP support" bit in the MS message. + +**Table 2 – Interpretation of MS message bits for BACP** + +| BACP support | Meaning | +|---------------------|------------------------------------------------------------------------------------------------------| +| 0 | Use the ITU-T G.994.1-based discovery/aggregation. Do not use BACP discovery/aggregation/management. | +| 1 | Use BACP for discovery/aggregation/management. Do not use ITU-T G.994.1-based discovery/aggregation. | + +Unlike the handshake operations of [IEEE 802.3-2005], this Recommendation defines the bonding layer to operate independently of the TPS-TC. Each line may select its TPS-TC independently of the others, as long as the maximum differential latency of the pairs is maintained as specified in this Recommendation. + +NOTE – This Ethernet bonding Recommendation uses the PME aggregation and PME aggregation discovery codepoints in [ITU-T G.994.1]. The definition of these variables is in clause 45.2.3.20 (PME aggregation) and 45.2.6.8 (PME aggregation discovery) of [IEEE 802.3-2005]. The transactions used to exchange these codepoints (e.g., "Get", "Set if Clear", "Clear if Same") are defined in clause 61.4 of [IEEE 802.3-2005]. An example of the aggregation discovery procedure is contained in clause 61A of [IEEE 802.3-2005]. + +# **9 Intentional temporary shutdown of some bonded lines** + +Customer premises equipment (CPE) with bonded DSL may temporarily shut down some lines in a bonded group of lines while keeping at least one other line of the group in operation. This could be done to reduce the power consumption of the CPE to extend the operating duration of a backup battery or to conserve energy during idle periods. The normal procedure for orderly shutdown of a DSL line may be used and later the DSL startup procedure may be used when all lines need to be active. The orderly shutdown procedure for VDSL2 is specified in clause 11.2.3.9 of [ITU-T G.993.2] and for ADSL2/2plus in clauses 9.5.3.1 and 9.5.3.5 of [ITU-T G.992.3]. When a portion, but not all, of the lines in a bonded group is shut down using the orderly shutdown procedure and later their operation resumes, the bonded group shall remain in service, without interruption of transmission. Furthermore, the service management function for the DSL access multiplexer (DSLAM) or the associated element management system (EMS) may need to be aware of the intentional shutdown of some lines so as to avoid unnecessary service alarms due to the resulting reduced bit-rate of the bonded DSL group. + +A service alarm should be reported if all lines in a bonded group are shut down or if a line has a disorderly shut down. + +For [ITU-T G.991.2], the behaviour in this situation is for further study. + +# Annex A + +## **Ethernet bonding with 64/65-octet encapsulation** + +(This annex forms an integral part of this Recommendation.) + +Clause 61.3.3 of [IEEE 802.3ah] specifies 64/65-octet encapsulation. This Recommendation shall be used in combination with the 64/65-octet encapsulation PTM-TC as defined in the individual ITU-T DSL transceiver Recommendations ITU-T G.99x-series. The normative references to clause 61.3.3 of [IEEE 802.3ah] are made in the applicable ITU-T Recommendation. + +NOTE – Clause 61.3.3.3 defines the 64/65-octet transmission convergence – cyclic redundancy check (TC-CRC) size. This may be either 16-bit or 32-bit depending on the error correcting capabilities of the underlying technology. The cyclic redundancy check (CRC) requirements are defined in the PTM-TC section of the applicable ITU-T Recommendation. + +# **Annex B** + +## **Ethernet bonding with HDLC encapsulation** + +(This annex forms an integral part of this Recommendation.) + +The specific normative requirements for HDLC encapsulation are contained in the applicable ITU-T Recommendation for the underlying transport technology. + +# Annex C + +## Frame-based protocol for discovery/aggregation and link management + +(This annex forms an integral part of this Recommendation.) + +This annex describes a frame-based protocol, referred to as the bonding aggregation control protocol (BACP) that exchanges information allowing two systems to control which PMEs are mapped to which PAFs in a simple and seamless manner. In this annex, a "system" is defined as a piece of equipment, such as a DSLAM or a CPE device, associated with a set of PAFs and PMEs. This protocol is used in lieu of the [ITU-T G.994.1] discovery/aggregation process defined in clause 8. + +This protocol is backward compatible with existing Ethernet bonding implementations and standards. + +## C.1 Bonding control architecture + +The bonding control architecture is shown in Figure C.1. A bonding control engine (BCE) sends and receives BACP data units (BACPDU). The BACPDU are Ethernet frames that are transmitted and received through a standard PAF function. A mux function between the MAC and MII interface is required to insert and remove BACPDU into the data path. BACPDU are identified by the headers of the Ethernet frame as discussed in clause C.4. + +NOTE – Architecturally the BCE is in a bonding control sublayer (BCS) similar to the Ethernet OAM sublayer shown in Figure 57-3 of [IEEE 802.3-2005]. + +![Figure C.1 – Bonding control architecture diagram showing three parallel paths. Each path consists of a MAC block at the top, followed by a dashed box labeled 'BCS' containing a 'Bonding control engine (access to all PAFs)' and a 'Mux' block. Below the BCS is a 'TC Client' section containing 'MII (optional)', 'MAC-PHY rate matching', and 'PME aggregation (optional)'. All three paths converge to a 'Flexible cross-connect (optional)' block, which is part of a 'PCS' section. Below this is a 'PME' section with 'TC (packet encapsulation)', 'PMA', and 'PMD' blocks. Vertical arrows on the right indicate the 'TC Client' and 'PME' layers. A label 'Control' is on the left, and a reference 'G.998.2(05)Amd.2_FC1' is at the bottom right.](75e4b78ee25f885d73120e3066a5253e_img.jpg) + +The diagram illustrates the bonding control architecture across three parallel lanes. At the top, each lane has a 'MAC' block. Below each 'MAC' is a 'Mux' block. A dashed box labeled 'BCS' (Bonding Control Sublayer) encloses the 'Bonding control engine (access to all PAFs)' and the 'Mux' blocks. Below the BCS is the 'TC Client' section, which includes 'MII (optional)', 'MAC-PHY rate matching', and 'PME aggregation (optional)'. All three lanes' 'PME aggregation' blocks connect to a common 'Flexible cross-connect (optional)' block. This block is part of the 'PCS' (Physical Coding Sublayer) section. Below the PCS is the 'PME' (Physical Medium Attachment) section, which includes 'TC (packet encapsulation)', 'PMA', and 'PMD' blocks. Vertical arrows on the right side of the diagram indicate the 'TC Client' and 'PME' layers. A label 'Control' is on the left side, and a reference 'G.998.2(05)Amd.2\_FC1' is at the bottom right. + +Figure C.1 – Bonding control architecture diagram showing three parallel paths. Each path consists of a MAC block at the top, followed by a dashed box labeled 'BCS' containing a 'Bonding control engine (access to all PAFs)' and a 'Mux' block. Below the BCS is a 'TC Client' section containing 'MII (optional)', 'MAC-PHY rate matching', and 'PME aggregation (optional)'. All three paths converge to a 'Flexible cross-connect (optional)' block, which is part of a 'PCS' section. Below this is a 'PME' section with 'TC (packet encapsulation)', 'PMA', and 'PMD' blocks. Vertical arrows on the right indicate the 'TC Client' and 'PME' layers. A label 'Control' is on the left, and a reference 'G.998.2(05)Amd.2\_FC1' is at the bottom right. + +Figure C.1 – Bonding control architecture + +The bonding control engine uses BACPDU to exchange information with a BCE on a remote system. The information in these frames is then used by the BCE to control the flexible cross-connect shown in Figure C.1, mapping specific PMEs to specific PAFs. All PMEs on which BACP is enabled are 'PAF enabled', meaning that the PAF function is always in use, and the PME carries fragments rather than full Ethernet frames. This ensures that the BCE simply controls the flexible cross-connect, and does not have to change encapsulations on the PMEs. + +Because the BCE essentially moves PMEs from one PAF to another, systems that implement BACP should be careful in that moving PMEs from PAFs that are carrying user (higher layer) data, such as an Internet service, since they would have a clear effect on that service. Implementations should take care in protecting higher layer services as the protocol operates and PME aggregation or removal occurs. + +To achieve seamless insertion and removal of PMEs into a bonded group, the cross-connect and PAF must support the ability to separately control the receive and transmit connectivity between a PME and a PAF. For example, it must (temporarily) be possible for a PME to be mapped to a PAF receive (reassembly) process, but not to the PAF transmit (segmentation) process. + +It is also assumed that the BCE has knowledge of when PMEs are activated and deactivated. Once a PME is activated (i.e., able to transmit and receive fragments), BACP can be used to control to which PAF the PME is connected, and provide smooth transitions of a PME into or out of a PAF. + +Because BACP uses standard Ethernet frames transmitted through the PAF, the BCE does not control over which PME(s) the BACPDU are sent. Thus BACP cannot be used for per-PME link monitoring. + +## C.2 Operational overview of bonding aggregation control protocol + +This clause provides an overview of the operational behaviour of the BCE and BACP protocol. Additional details are supplied in later clauses. + +### C.2.1 Group identification and bonding eligibility + +To determine which PMEs are eligible to be aggregated with other PMEs, a system assigns a group ID (GID) to each PME. The GID parameter is specified in clause C.3.1.1. + +Two PMEs are eligible to be aggregated if they have the same GID on both systems to which they are attached. Specifically, if the GIDs associated with PME1 on the local system and remote systems are G1local and G1remote, respectively, and if the GIDs associated with PME2 are G2local and G2remote, then PME1 and PME2 are eligible to be aggregated if G1local = G2local and G1remote = G2remote. In the typical environment, a CPE device would assign the same GID to all of the PMEs attached to it, in order to assert that all of its PMEs should be in the same bonded group. + +![Diagram illustrating Group eligibility example. It shows two systems (left and right) connected by four horizontal lines representing PMEs. The left system has GIDs 1, 1, 2, and 3 for the four PMEs. The right system has GIDs 100, 100, 1000, and 1000 for the same PMEs. Dashed ovals group the PMEs with matching GIDs on both sides: the top two (GID 1/100) and the bottom two (GID 2/1000 and 3/1000).](627c5195eaae3bc7e34cbc4dbdb6f9a8_img.jpg) + +The diagram shows two rectangular boxes representing network systems. The left box contains four entries for PMEs, each with a GID: GID = 1, GID = 1, GID = 2, and GID = 3. The right box contains four entries for PMEs, each with a GID: GID = 100, GID = 100, GID = 1000, and GID = 1000. Four horizontal lines connect the PMEs in the left box to the PMEs in the right box. Dashed ovals group the PMEs that have matching GIDs on both sides: the top two PMEs (GID 1 on the left, GID 100 on the right) and the bottom two PMEs (GID 2 and 3 on the left, GID 1000 on the right). Below the diagram is the text G.998.2(05)Amd.2\_FC2. + +Diagram illustrating Group eligibility example. It shows two systems (left and right) connected by four horizontal lines representing PMEs. The left system has GIDs 1, 1, 2, and 3 for the four PMEs. The right system has GIDs 100, 100, 1000, and 1000 for the same PMEs. Dashed ovals group the PMEs with matching GIDs on both sides: the top two (GID 1/100) and the bottom two (GID 2/1000 and 3/1000). + +Figure C.2 – Group eligibility example + +An example of determining group eligibility is given in Figure C.2. In this example, the top two PMEs both have GIDs of (1, 100), and are thus eligible to be aggregated. The bottom two PMEs have unique GIDs ((2, 1000) and (3, 1000)) and are thus not eligible for aggregation with any of the other PMEs. + +If each system uses a single GID across all PMEs, then all PMEs among the systems will be eligible to be aggregated together. Alternatively, "fixed" aggregation groups could be configured (most likely on a central office (CO) system), each with their own GID. For example, PMEs 1-4 could be given one GID, PMEs 5-8 a different GID, and PMEs 9-15 yet a different GID. The system would then ensure that no aggregation can occur across PMEs in these three different groups based on this GID assignment policy. These are expected to be two common methods of using the GIDs. + +Management operations can be used to configure group eligibility by means of the GID based on local policy and configuration. + +GIDs define *group eligibility*. GIDs do not define actual bonding groups. Group makeup is determined by the current connectivity of the cross-connect and the PME status. PMEs with different GIDs shall never be connected to the same PAF. PMEs with the same GID may be connected to different PAFs. + +### C.2.2 PME identification + +The PMEs require identification within two different contexts for BACP: within the group ID context (eligibility to be a member of a bonding group), and within the PAF context (role as actual member of a bonding group). + +The PME identification (PME ID) parameter identifies the PME within the context of a particular PAF. It is specified in clause C.3.1.3. PME identification is required for multiple reasons, e.g., when adding/removing PMEs from an aggregate it is vital that the correct PME be identified for that operation. In case the implementation supports IEEE 802.3 clause 57 OAM, and when the implementation desires to retrieve statistics or status on a particular PME within an aggregate, the PME ID is required to access the information on a particular PME. In this context, the PME ID is an integer in the range 0..31, and identifies which of the 32 potential PMEs in this aggregate the OAM request is targeting. + +The stream ID is an identifier that is unique within a group ID (i.e., PMEs with the same GID). The stream ID parameter is specified in clause C.3.1.2. Each PME is assigned a stream ID that uniquely identifies that PME within that group ID. The use of the stream ID allows group eligibility to extend beyond 32 streams. This is important in the following respect. Although any PAF is limited by this Recommendation (and IEEE 802.3) to at most 32 streams in a PAF, many implementations in the market allow those 32 streams to be selected from a much larger set. For example, a line card may have 48 ports and any of those ports could be aggregated with any other (up to at most 32 in any one PAF). Or a system may support hundreds of ports with a centralized bonding capability such that any stream can be aggregated with any other. Generalized discovery across a large number of potential streams is supported in BACP via the combination of the group and stream identifiers. This is useful for systems that are supposed to be plug-and-play interconnectable in a true grid network (e.g., on enterprise or campus scale) and where group eligibility is not restricted through network operator configuration to a maximum of 32 pairs. + +### C.2.3 PME and PAF initialization + +PMEs are initialized as the only PME in their PAF. When the PAF is able to transmit and receive fragments, the bonding control engine can begin the transmission of BACPDUs that advertise the local GID, PME ID and stream ID for that PME through the PAF for that PME. BACPDUs are transmitted through every PAF on which the protocol is enabled as specified in clause C.3.2.5. When the BCE receives a BACPDUs on a single-PME PAF, it knows the GID, PME ID and stream ID for that PME as defined by the remote system. This allows the local BCE to determine the group eligibility for that PME (e.g., can this PME be aggregated into some other PAF). This absolute PME identification mechanism requires that the size of a newly initialized PAF be limited to a single PME. + +After determining eligibility, the BCE may decide to initiate a PME transfer to another PAF. A PME transfer allows a PME in a single PAF to be transferred seamlessly to another PAF. The BCE is not required to initiate a PME transfer, and can reject or postpone a transfer request from a remote system. + +For example, a BCE may decide not to initiate a PME transfer because the desired target PAF already has a sufficient number of PMEs. This may be because of a physical limit of the PAF (e.g., it only supports 4-pair bonding and already has 4-pair in it), or because of a logical limitation (it was provisioned to only allow 4-pair in a PAF and the target PAF has 4-pair already). Other reasons a BCE may not initiate a PME transfer request after determining that the PME is eligible include that + +the PME is not of sufficient quality (too many errors), the PME is not of sufficient bandwidth (would violate the 4x rate differential), or that differential delay with other PMEs in the target PAF would be too great (violate the differential delay requirements of a bonded group). + +It is up to the local BCE policies to determine if a BCE transfer should be initiated, and up to the remote BCE policies to accept and progress a transfer request. + +### **C.2.4 Transferring a PME from a single-PME PAF to an existing PAF** + +Transferring a PME from one PAF to another PAF is a seamless process in which no data loss is incurred on the target PAF, but which can only be executed for a source PAF that is a single-PME PAF. The source PAF will of course lose its only PME. The source PAF PME is expected not to be carrying data traffic, but if it is, then that data traffic will all be dropped once the PME transfer begins. + +The following process outlines the procedure for transferring a PME from its single PAF to another PAF that has one or more existing PMEs. Within the scope of the source and target PAF, PMEs and streams have a one-to-one mapping. By transferring a PME, only the one related stream is transferred. Other streams carried on the same transceiver but aggregated through other PAFs remain unaffected by this process. + +- 1) The BCE decides to initiate a transfer of PME A in PAF X (a single-PME PAF) to PAF Y (which already has one or more PMEs). +- 2) The BCE selects a PME ID for the PME A within the target PAF Y. The BCE then transmits a BACPDU indicating the selected PME ID (as well as other parameters) through the target PAF Y. The BCE waits for the far end to acknowledge the local PME ID selection, and acknowledges the far end PME ID selection. At this point, both systems have selected a PME ID that is applicable to the target PAF Y, and both systems have received the selected PME ID from the remote system. +- 3) When the PME IDs have been exchanged and confirmed through PAF Y, the BCE disconnects PME A from its current PAF X. At this point, no frames will be transmitted through PAF X. This is signalled to the remote system via a BACPDU transmitted through PAF Y, and the local system waits for the confirmation that the remote system also has disconnected PME A. +- 4) Once both sides have disconnected PME A from the transmit path of any PAF, the receive side can be switched to PAF Y. When the local system has switched the receive path to PAF Y, it signals this status change via a BACPDU transmitted through PAF Y. At this point, PME A is ready to receive traffic on PAF Y, but neither side is transmitting on it. +- 5) After the local system receives confirmation that PME A is connected to the receive path of PAF Y on the remote system, it is free to connect PME A to the transmit path of PAF Y. + +At the end of this process, PME A is connected to PAF Y both locally and remotely. And because the receive path was activated before the transmit path was activated, there was no data loss on PAF Y because of the addition of PME A. + +### **C.2.5 Transferring a PME from an existing PAF to a single-PME PAF** + +Transferring a PME from a PAF with multiple PMEs is basically the reverse of the earlier process for adding a PME. The PME is transferred from its existing PAF to a PAF in which it is the only PME. + +Transferring a single PME out of an existing PAF is a seamless process in which no data loss is incurred on the current PAF if the offered traffic rate is supported by the remaining PMEs. Within the scope of the source and target PAF, PMEs and streams have a one-to-one mapping. By transferring a PME into a newly created PAF, only the one related stream is transferred. Other streams carried on the same transceiver but aggregated through other PAFs remain unaffected by this process. + +The following process outlines the procedure for removing a PME from an aggregate PAF to its single PAF: + +- 1) The BCE decides to initiate a transfer of PME A out of PAF Y (which has two or more PMEs) to an empty (no PME) PAF (PAF X). +- 2) The BCE disconnects PME A from the transmit path of PAF Y, and signals this status change to the remote BCE on PAF Y. The PME A remains connected for the receive path of PAF Y. +- 3) When the BCE receives confirmation from the remote side that it also has disconnected the transmit path for PME A in PAF Y and that the remote side has received the notification sent by the local BCE, the BCE disconnects the receive side of PME A from PAF Y and connects the transmit and receive paths of PME A to an empty PAF (PAF X). +- 4) The BCE signals the remote BCE on PAF X that the transmit and receive paths have been connected to PAF X. +- 5) When the BCE receives confirmation that the remote side has also connected PME A to PAF X, and that the remote side has received the notification sent by the local BCE, then PME A has been successfully transferred into its own PAF. + +NOTE – If the transfer was initiated because the PME has excessive errors on the related stream, such confirmation may not be received. If the transceiver is to be reinitialized, other streams carried on the same transceiver should be transferred to a single-PME PAF first to maintain seamlessness. + +At this point, PME A has been seamlessly removed from PAF Y and transferred into its own single-PME PAF X. + +## **C.3 Protocol operation** + +The following clauses describe BACP operation in more detail. + +### **C.3.1 Protocol variables and attributes** + +This clause identifies the primary variables and attributes of BACP. These attributes control the operation of the protocol, and the variables are communicated via BACPDUs. These parameters are necessary only within the context of this protocol. PMEs that are not eligible to be bonded, or PMEs on which this protocol is not enabled, do not require these parameters to be configured. + +##### **C.3.1.1 Group ID** + +The group ID (GID) is a universally unique 6-octet identifier assigned by each system that identifies a set of PMEs which are eligible to be aggregated on the local system. When two PMEs have the same GID on a system, they are eligible to be aggregated on that system. + +Clause C.2.1 describes how GIDs can be used to determine group eligibility. This value is initialized by management. + +The GID of a PME shall not be changed while that PME is aggregated with any other PME. The GID may be changed while the PME is in a single-PME PAF, either during BACP initialization (clause C.3.2.1) or after a PME has been transferred out of a bonded group (clause C.3.2.3). + +If a transceiver carries multiple logically separated data streams over the gamma reference point (e.g., in the case of dual latency operation), then each of those streams shall be assigned to a different GID. + +##### C.3.1.2 Stream ID + +As discussed in clause C.2.2, the stream ID is a 2-octet identifier that uniquely identifies a particular PME within a group ID (i.e., PMEs with the same GID). A group + stream ID is required for each PME under the control of this BCE. Each stream is assigned a stream ID that uniquely identifies that stream within its group ID, so the combination of GID and stream ID is a universally unique identifier for that PME. The allocation of the stream ID values is implementation-specific and no particular structure is specified. + +The stream ID shall not be changed while that PME is aggregated with any other PME. The stream ID may be changed while the PME is in a single-PME PAF, either during BACP initialization (clause C.3.2.1) or after a PME has been transferred out of a bonded group (clause C.3.2.3). + +If a transceiver carries multiple logically separated data streams over the gamma reference point (e.g., in the case of dual latency operation), then each of those streams may be assigned the same or a different stream ID. + +This value is initialized by management. + +##### C.3.1.3 PME ID + +The PME ID is an integer in the range 0..31, and identifies a particular PME out of the 32 potential PMEs in a PAF. This is the same value that would be used by IEEE 802.3 clause 57 OAM to retrieve statistics or status on a particular PME within an aggregate. This relative PME identifier (e.g., an identifier that has context only within a particular PAF) is referred to as the PME ID. + +This value is initialized by the BCE when the PME is selected to be mapped or moved to a specific PAF, and this value identifies this PME within the PAF over which the BACPDUs are sent or received. + +The allocation of the PME ID values is implementation-specific and no particular structure is specified. + +If a transceiver carries multiple logically separated data streams over the gamma reference point (e.g., in the case of dual latency operation), then each of those streams may be assigned the same or a different PME\_ID. + +##### C.3.1.4 PME status + +Each of the 32 potential PME positions within a PAF (representing PME IDs 0 to 31) has an associated PME status value. The valid PME status values are: + +- **Unknown (0):** Information about this PME is not yet known. +- **Unassigned (1):** The PAF does not have a PME in this position. +- **Assigned (2):** The PME has been assigned a PME ID for the PAF but is not connected to the PAF in either the transmit or receive direction. +- **Moving (3):** The PME is in the process of moving into this PAF. It is currently not connected to any PAF on the local side, and BCE is awaiting confirmation that the PME is not connected to any PAF on the remote side. +- **RxOnly (4):** The PME is connected to the advertising PAF reassembly process, but is not connected to the transmit path of any PAF. +- **TxRx (5):** The PME is fully connected to the transmit and receive paths of the advertising PAF. This is the normal fully operational status. + +The local PME status shall not take the value "Unknown". Only the remote PME status may take the value "Unknown" when the local BCE has not yet received information from the remote BCE on the PAF, which is then to be resolved through a type length value (TLV) exchange. + +The PME status is carried in a 4-bit field as an unsigned integer (e.g., RxOnly(4) is carried as 0100). + +##### C.3.1.5 PME status array + +The PME status is advertised as an array of 32 4-bit fields (16-octets) in the PME status array field of the local info TLV. The PME ID for a specific PME is used as the index into this array to identify the status of that specific PME. See Figure C.3. + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|--------|---|---|---|--------|---|---|---|--------|---|---|---|--------|---|---|---|--------|---|---|---|--------|---|---|---|--------|---|---|---|--------|---|---|---| +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | +| PME 0 | | | | PME 1 | | | | PME 2 | | | | PME 3 | | | | PME 4 | | | | PME 5 | | | | PME 6 | | | | PME 7 | | | | +| PME 8 | | | | PME 9 | | | | PME 10 | | | | PME 11 | | | | PME 12 | | | | PME 13 | | | | PME 14 | | | | PME 15 | | | | +| PME 16 | | | | PME 17 | | | | PME 18 | | | | PME 19 | | | | PME 20 | | | | PME 21 | | | | PME 22 | | | | PME 23 | | | | +| PME 24 | | | | PME 25 | | | | PME 26 | | | | PME 27 | | | | PME 28 | | | | PME 29 | | | | PME 30 | | | | PME 31 | | | | + +Figure C.3 – PME status array + +##### C.3.1.6 Remote group ID + +Each PAF has a remote group ID. The remote GID is the GID value in the local info TLV most recently received from the remote BCE on that PAF. This value is included in the remote group ID field of the remote info TLV in each BACPDUs transmitted on that PAF. + +##### C.3.1.7 Remote stream ID + +Each stream under the control of the BCE has an associated remote stream ID. The remote stream ID is the stream ID value in the assignment TLV from the remote BCE for this stream as discovered during the Initialization process. When an assignment TLV is received from a remote BCE, the association between the remote stream ID and local stream ID is stored. The BCE must be able to associate the PME ID received in that assignment TLV and the PAF over which it was received with that remote stream ID. + +Thus, from just its local stream ID, the BCE can associate a remote stream ID, the PME ID of that stream as identified by the remote system, and the PAF in which that stream is aggregated. + +###### C.3.1.7.1 Remote PME ID + +Each stream under the control of the BCE has an associated remote PME ID. The remote PME ID is the PME ID value in the assignment TLV most recently received from the remote BCE for this stream. When an assignment TLV is received from a remote BCE, the association between the remote PME ID and local stream ID is stored. + +##### C.3.1.8 Remote PME status array + +Each PAF has an associated remote PME status array. This array reflects the status of the PMEs as last communicated by the remote BCE and received by the local BCE. The remote PME ID for a specific PME is used as the index into the remote PME status array to identify the remote status of that specific PME. + +#### C.3.2 Protocol operation + +##### C.3.2.1 BACP initialization + +Each PME shall be initialized into a PAF with only that PME. The local BCE has no preceded information about the remote BCE, and BACP itself provides the discovery process. + +BACP initialization is described below. At the completion of the BACP initialization phase, the local BCE knows the stream ID, group ID and PME ID used by the remote BCE for each PME in the initialized PAF. At the completion of the BACP initialization, data flow can begin immediately on the PAF. + +The BACP initialization process happens separately for each PME. There is at most one initialization happening on a PAF because the PMEs are initialized as a single-PME PAF, and multiple PAFs may be initialized in parallel. + +A PME is initialized into its own PAF as the only PME in that PAF. The PME's initial local status is TxRx and its remote status is Unknown with that PAF and BACPDUs can be sent through the PAF over that single PME. The BCE transmits BACPDUs over that PAF until it receives BACPDUs from the remote entity that confirm it has received the local information. Each BACPDUs frame contains the local information to be communicated to the remote BCE, as well as a copy of the latest received information from the remote BCE, so that the remote BCE can confirm that the local BCE has received its information. + +Whenever there is a PME in the Initialize or WaitForInitConfirmation state, the assignment TLV must be included in the BACPDUs for that PME. The local TLV includes the group ID and the assignment TLV includes a stream ID and PME ID for the single PME. The group ID and stream ID are critical to the protocol operation as their combination is the only constant identifier for this stream in a multi-PME PAF. While a PME is being moved from one PAF to another (as defined in clauses C.3.2.2 and C.3.2.3), neither the group ID nor the stream ID is allowed to change as they are used to identify which PME is being moved. Only while a PME is part of a single-PME PAF, may its group ID and stream ID be changed (resulting in sending TLVs to notify the far-end BCE). + +Whenever an assignment TLV is received in a single-PME PAF, the BCE must store the relationship between the stream ID and that PME. The stream ID might be received in BACPDUs on any PAF, and the local BCE must be able to associate the stream ID with this PME. + +In the following state machines, [X,Y] is used to represent the local information about the PME status, where X is the current local status of the PME, and Y is the most recently received status of the PME on the far end. For example, [TxRx, Unknown] represents when the local system has the PME connected to its PAF in both the transmit and receive directions, and it has not yet heard the status of the PME on the remote BCE. + +![Figure C.4 – Single-PME PAF state machine diagram. The diagram shows three states: Initialize, WaitForInitConfirmation, and EligibleForAggregation. Transitions are triggered by BACPDUs (Tx or Rx) with specific status information [TxRx, Unknown] or [TxRx, TxRx].](eb5677b570ab2a3e9d8f5d35ca5b8a4d_img.jpg) + +``` + +stateDiagram-v2 + [*] --> Initialize : Link up + Initialize --> WaitForInitConfirmation : Rx BACPDUs[TxRx, Unknown] + Initialize --> EligibleForAggregation : Rx BACPDUs[TxRx, TxRx] + WaitForInitConfirmation --> Initialize : Rx BACPDUs[TxRx, Unknown] + WaitForInitConfirmation --> EligibleForAggregation : Rx BACPDUs[TxRx, TxRx] + EligibleForAggregation --> Initialize : Rx BACPDUs[TxRx, Unknown] + EligibleForAggregation --> WaitForInitConfirmation : Rx BACPDUs[TxRx, TxRx] + +``` + +The state machine starts at an initial state (represented by a circle) labeled 'Link up' leading to the 'Initialize' state. The 'Initialize' state contains the action 'Tx BACPDUs[TxRx, Unknown]'. From 'Initialize', there are two outgoing transitions: one to 'WaitForInitConfirmation' triggered by 'Rx BACPDUs[TxRx, Unknown]' and another to 'EligibleForAggregation' triggered by 'Rx BACPDUs[TxRx, TxRx]'. The 'WaitForInitConfirmation' state contains the action 'Tx BACPDUs[TxRx, TxRx]'. From 'WaitForInitConfirmation', there are two outgoing transitions: one back to 'Initialize' triggered by 'Rx BACPDUs[TxRx, Unknown]' and another to 'EligibleForAggregation' triggered by 'Rx BACPDUs[TxRx, TxRx]'. The 'EligibleForAggregation' state contains the action 'Tx BACPDUs[TxRx, TxRx]'. From 'EligibleForAggregation', there are two outgoing transitions: one back to 'Initialize' triggered by 'Rx BACPDUs[TxRx, Unknown]' and another back to 'WaitForInitConfirmation' triggered by 'Rx BACPDUs[TxRx, TxRx]'. A small note 'G.998.2(05)Amd.2\_FC4' is present at the bottom right of the diagram. + +Figure C.4 – Single-PME PAF state machine diagram. The diagram shows three states: Initialize, WaitForInitConfirmation, and EligibleForAggregation. Transitions are triggered by BACPDUs (Tx or Rx) with specific status information [TxRx, Unknown] or [TxRx, TxRx]. + +**Figure C.4 – Single-PME PAF state machine** + +The operation *Tx BACPDUs[TxRx, Unknown]* represents that the local BCE is transmitting BACPDUs with the PME status information [TxRx, Unknown] for the single PME in this PAF. In the BACPDUs, other local PME status values are set to Unassigned and other remote PME status values are also set to Unknown. The transitions *Rx BACPDUs[TxRx, TxRx]* occur when the local BCE receives a BACPDUs with the PME status information [TxRx, TxRx]. + +The target state for this phase is for the PME to be in the EligibleForAggregation state. At this point, the BCE is free to transition the PME into another PAF. + +##### C.3.2.2 PME transfer into a bonded group + +Transferring a PME into a bonded group consists of taking the PME through a series of phases, where each phase is complete when both the local and remote sides have confirmed, and received confirmation, that the status transition has been accomplished. + +All referenced BACPDUs transmissions occur on the target PAF to which the PME is being transferred. + +###### C.3.2.2.1 Assigning a PME ID for the stream on the target PAF + +Once the BCE decides to transfer a PME to a specific target PAF, the PME ID for that PME within the target PAF must be assigned and communicated with the remote BCE. + +Whenever a BCE transmits a BACPDU with the local PME status of Assigned, an assignment TLV must also be included. This TLV contains the stream ID of the transferring PME as well as the relative PME ID for that PME with this target PAF. + +Whenever a BCE receives an assignment TLV, it stores the relationship between the stream ID and PME ID as indicated by the remote BCE. The inclusion of the stream ID by the remote BCE allows the local BCE to know which PME the remote BCE is trying to transfer to this PAF. The local BCE can then find that PME and continue the PME transfer process if desired. + +![Figure C.5 – PME ID assignment state machine diagram](474a819357587e34949a3e110ff19b30_img.jpg) + +``` + +stateDiagram-v2 + [*] --> AssignPMeToBearer: BCE decides to transfer PME to this PAF + AssignPMeToBearer --> WaitForConfirmation: Tx BACPDU[Assigned, Unassigned] + AssignPMeToBearer --> EligibleToTransfer: Tx BACPDU[Assigned, Assigned] + WaitForConfirmation --> WaitForConfirmation: Rx BACPDU[Assigned, Unassigned] + WaitForConfirmation --> EligibleToTransfer: Rx BACPDU[Assigned, Assigned] + EligibleToTransfer --> WaitForConfirmation: Tx BACPDU[Assigned, Assigned] + EligibleToTransfer --> [*]: To disconnectingPME + +``` + +The state machine for PME ID assignment starts with an initial state where the BCE decides to transfer a PME. It then enters the **AssignPMeToBearer** state, transmitting a BACPDU with *[Assigned, Unassigned]* status. From here, it can either move to the **WaitForConfirmation** state (if the remote responds with *[Assigned, Unassigned]*) or the **EligibleToTransfer** state (if the remote responds with *[Assigned, Assigned]*). In **WaitForConfirmation**, it retransmits *[Assigned, Assigned]* upon receiving *[Assigned, Unassigned]* and moves to **EligibleToTransfer** upon receiving *[Assigned, Assigned]*. In **EligibleToTransfer**, it retransmits *[Assigned, Assigned]* upon receiving *[Assigned, Assigned]* and can transition to **To disconnectingPME**. + +Figure C.5 – PME ID assignment state machine diagram + +Figure C.5 – PME ID assignment state machine + +This assignment process is complete when the BCE has received confirmation that the remote system has received its transmitted assignment TLV information. + +##### C.3.2.2.2 Disconnecting the PAF from the single-PME PAF + +Once both the local and remote BCEs know the target PME to be moved as well as how that PME shall be identified within the target PAF, the BCE can begin to move the PME to this PAF. The first step in this process is for both the local and remote systems to disconnect the PME from its current PAF. Once the PME is disconnected locally from the local PAF, the PME moves to the DisconnectingPME state. This process is shown in Figure C.6. + +![Figure C.6 – PME disconnect state machine diagram](e9b43ac020435f8121e8592f31afdc52_img.jpg) + +``` + +stateDiagram-v2 + [*] --> DisconnectingPME: From EligibleToTransfer + DisconnectingPME --> WaitForConfirmation: Tx BACPDU[Moving, Assigned] + DisconnectingPME --> PMEDisconnected: Tx BACPDU[Moving, Moving] + WaitForConfirmation --> WaitForConfirmation: Rx BACPDU[Moving, Assigned] + WaitForConfirmation --> PMEDisconnected: Rx BACPDU[Moving, Moving] + PMEDisconnected --> [*]: To connectingPMERx + +``` + +The state machine for PME disconnect starts from the **EligibleToTransfer** state, entering **DisconnectingPME** and transmitting a BACPDU with *[Moving, Assigned]* status. It can then move to the **WaitForConfirmation** state (if the remote responds with *[Moving, Assigned]*) or the **PMEDisconnected** state (if the remote responds with *[Moving, Moving]*). In **WaitForConfirmation**, it retransmits *[Moving, Moving]* upon receiving *[Moving, Assigned]* and moves to **PMEDisconnected** upon receiving *[Moving, Moving]*. In **PMEDisconnected**, it can transition to **To connectingPMERx**. + +Figure C.6 – PME disconnect state machine diagram + +Figure C.6 – PME disconnect state machine + +Disconnecting the PME from the single-PME PAF is complete when the BCE has received confirmation that the remote system received the locally transmitted status information. At this point the PME is in the PMEDisconnected state. + +##### C.3.2.2.3 Connecting the PME Rx to the target PAF + +Once the PME has been disconnected from its previous PAF, the PME can be attached to the receive path of the target PAF. This basically sets up the receive process for this PME before the transmit process is established. By doing so, the PME transfer can be made in a seamless manner. Once the BCE locally connects the PME receive path to the target PAF, the PME can transfer into the ConnectingPMERx state. The process is shown in Figure C.7. + +![Figure C.7 – PME Rx connect state machine diagram](fa01531ea2c45beeb4036005da3037a4_img.jpg) + +``` + +stateDiagram-v2 + [*] --> ConnectingPMERx : From PMEDisconnected + state "ConnectingPMERx" as ConnectingPMERx { + Tx BACPDUs[RxOnly,Moving] + } + ConnectingPMERx --> WaitForConfirmation : Rx BACPDUs[RxOnly,Moving] + state "WaitForConfirmation" as WaitForConfirmation { + Tx BACPDUs[RxOnly,RxOnly] + } + WaitForConfirmation --> PMERxConnected : Rx BACPDUs[RxOnly,RxOnly] + state "PMERxConnected" as PMERxConnected { + Tx BACPDUs[RxOnly,RxOnly] + } + PMERxConnected --> [*] : To connectingPMETx + PMERxConnected --> WaitForConfirmation : Rx BACPDUs[RxOnly,RxOnly] + WaitForConfirmation --> WaitForConfirmation : Rx BACPDUs[RxOnly,Moving] + G.998.2(05)Amd._FC7 + +``` + +Figure C.7 – PME Rx connect state machine diagram + +Figure C.7 – PME Rx connect state machine + +Connecting the PME receive path to the target PAF is complete when the BCE has received confirmation that the remote system received the locally transmitted status information and has performed a similar connection. + +###### C.3.2.2.4 Connecting the PME Tx to the target PAF + +The final phase of the PME transfer is enabling the transmit path on the target PAF for the transferring PME. The BCE begins the process by locally connecting the transmit path of the PME to the target PAF. It then signals this change to the remote BCE and awaits confirmation that the remote BCE has made a similar connection and received the status information transmitted by the local BCE. + +![Figure C.8 – PME Tx connect state machine diagram](24c9e038a791677ed33100667b64f7e6_img.jpg) + +``` + +stateDiagram-v2 + [*] --> ConnectingPMETx : From PMERxConnected + state "ConnectingPMETx" as ConnectingPMETx { + Tx BACPDUs[TxRx,RxOnly] + } + ConnectingPMETx --> WaitForConfirmation : Rx BACPDUs[TxRx,RxOnly] + state "WaitForConfirmation" as WaitForConfirmation { + Tx BACPDUs[TxRx,TxRx] + } + WaitForConfirmation --> PMEConnected : Rx BACPDUs[TxRx,TxRx] + state "PMEConnected" as PMEConnected { + Tx BACPDUs[TxRx,TxRx] + } + PMEConnected --> [*] + PMEConnected --> WaitForConfirmation : Rx BACPDUs[TxRx,TxRx] + WaitForConfirmation --> WaitForConfirmation : Rx BACPDUs[TxRx,RxOnly] + G.998.2(05)Amd.2_FC8 + +``` + +Figure C.8 – PME Tx connect state machine diagram + +Figure C.8 – PME Tx connect state machine + +Connecting the PME transmit path to the PAF is complete when the BCE has received confirmation that the remote system received the locally transmitted status information. + +#### C.3.2.3 PME transfer out of a bonded group + +This clause details the process for seamlessly removing a PME from a bonded group. As with the process of transferring a PME into a bonded group, the basic philosophy is that the local BCE takes an action, communicates that action to the remote BCE via the status array in BACPDUs, and waits for the remote BCE to acknowledge that change and make a similar change. + +###### C.3.2.3.1 Disconnecting the PME Tx from the current PAF + +The first step in transferring a PME out of an existing PAF is to disconnect the transmit path of the PME from the existing PAF so that data no longer flows over this PME. Once the PME is locally disconnected from the transmit path of the PAF, the BCE enters the DisconnectingPME Tx state for this PME and follows the state machine of Figure C.9. + +![Figure C.9 – PME Tx disconnect state machine diagram](dcf37c460c66ec011dbe6ca08de44ff9_img.jpg) + +``` + +stateDiagram-v2 + [*] --> DisconnectingPME Tx + state "DisconnectingPME Tx" as DisconnectingPME Tx + state "WaitForConfirmation" as WaitForConfirmation + state "PME Tx Disconnected" as PMETxDisconnected + DisconnectingPME Tx --> WaitForConfirmation : Rx BACPDUs [RxOnly, TxRx] + DisconnectingPME Tx --> PMETxDisconnected : Rx BACPDUs [RxOnly, RxOnly] + WaitForConfirmation --> PMETxDisconnected : Rx BACPDUs [RxOnly, RxOnly] + PMETxDisconnected --> WaitForConfirmation : Rx BACPDUs [RxOnly, TxRx] + +``` + +The state machine starts at an initial state where the BCE decides to transfer the PME out. It enters the **DisconnectingPME Tx** state, where it transmits BACPDUs with *Tx BACPDUs [RxOnly, TxRx]*. From here, two transitions are possible based on received BACPDUs: if *Rx BACPDUs [RxOnly, TxRx]* are received, it moves to the **WaitForConfirmation** state; if *Rx BACPDUs [RxOnly, RxOnly]* are received, it moves to the **PME Tx Disconnected** state. In the **WaitForConfirmation** state, it transmits *Tx BACPDUs [RxOnly, RxOnly]*. A transition to the **PME Tx Disconnected** state occurs if *Rx BACPDUs [RxOnly, RxOnly]* are received. A return to the **WaitForConfirmation** state occurs if *Rx BACPDUs [RxOnly, TxRx]* are received. The **PME Tx Disconnected** state transmits *Tx BACPDUs [RxOnly, RxOnly]*. + +Figure C.9 – PME Tx disconnect state machine diagram + +Figure C.9 – PME Tx disconnect state machine + +At the end of this phase, the PME transfer path is not connected to any PAF. + +###### C.3.2.3.2 Disconnecting the PME Rx from the existing PAF + +Once the PME is no longer connected to any transmit path, the BCE can switch the receive path from the existing PAF to any 'empty' PAF. This is actually done in two parts – disconnecting the PME receive path from the current PAF, and then re-connecting it to a new (empty) PAF. For the disconnect process, the BACPDUs are transferred over the existing PAF, where the PME is switched from the RxOnly status to the Unassigned status. Once this status change has been communicated and confirmed on the existing PAF, the PME is no longer in the PAF. This is shown in Figure C.10. + +![Figure C.10 – PME Rx disconnect state machine diagram](fc0735d325f0ebd9214171975c68a888_img.jpg) + +``` + +stateDiagram-v2 + [*] --> DisconnectingPMERx + state "DisconnectingPMERx" as DisconnectingPMERx + state "WaitForConfirmation" as WaitForConfirmation + state "PME Disconnected" as PMEDisconnected + DisconnectingPMERx --> WaitForConfirmation : Rx BACPDUs [Unassigned, RxOnly] + DisconnectingPMERx --> PMEDisconnected : Rx BACPDUs [Unassigned, Unassigned] + WaitForConfirmation --> PMEDisconnected : Rx BACPDUs [Unassigned, Unassigned] + PMEDisconnected --> WaitForConfirmation : Rx BACPDUs [Unassigned, RxOnly] + +``` + +The state machine starts at an initial state labeled *From PMETxDisconnected*. It enters the **DisconnectingPMERx** state, where it transmits BACPDUs with *Tx BACPDUs [Unassigned, RxOnly]*. Two transitions are possible based on received BACPDUs: if *Rx BACPDUs [Unassigned, RxOnly]* are received, it moves to the **WaitForConfirmation** state; if *Rx BACPDUs [Unassigned, Unassigned]* are received, it moves to the **PME Disconnected** state. In the **WaitForConfirmation** state, it transmits *Tx BACPDUs [Unassigned, Unassigned]*. A transition to the **PME Disconnected** state occurs if *Rx BACPDUs [Unassigned, Unassigned]* are received. A return to the **WaitForConfirmation** state occurs if *Rx BACPDUs [Unassigned, RxOnly]* are received. The **PME Disconnected** state transmits *Tx BACPDUs [Unassigned, Unassigned]*. + +Figure C.10 – PME Rx disconnect state machine diagram + +Figure C.10 – PME Rx disconnect state machine + +When this phase is complete, the PME is not connected to any PAF. In particular, the PME ID associated with the removed PME is no longer in use or relevant in the PAF from which it was removed, and that PME ID may be used for other purposes. + +A PME shall not be disconnected if it is part of a single-PME PAF. + +###### C.3.2.3.3 Connecting the PME to an empty PAF + +Connecting the PME to an empty PAF consists of the BCE connecting the PME to the receive and transmit paths of any empty PAF, and starting with the initialization process as if this PME was just initialized into a single-PME PAF (clause C.3.2.1). + +#### C.3.2.4 Termination + +If the transceiver associated with a PME which is a member of an active PAF reinitializes, then after a vendor-discretionary timeout, the PME status shall be changed to "Unassigned" (i.e., removal from the active PAF, with notification TLVs sent to the far end BCE) and BACP initialization shall occur for this PME as specified in clause C.3.2.1. If the PME is able to transmit and receive fragments and the remote PME status has not been changed to "Unassigned" within the timeout period, then the local PME status remains as TxRx, without BACP reinitialization. To minimize data loss, the PAF should not send fragments to this PME while the PME is not able to transmit fragments on the line. + +#### C.3.2.5 BACPDU re-transmissions and frequency + +It is the responsibility of the BCE to ensure that all status changes are acknowledged by the remote BCE. If a BCE does not receive an acknowledgement of a transmitted status change, it should re-transmit that status several times until it becomes acknowledged, or until the BCE gives up on making that transition. + +It is recommended that, by default, a BCE retransmit three times and provide a window of one second for an acknowledgement to be received. + +There is no requirement to transmit BACPDU when the local and remote BCEs have synchronized information. BACPDU need only be exchanged to synchronize status change information. + +The local BCE shall send a BACPDU only when its local status changes (to indicate that local status change to the remote end) or when it receives a BACPDU with changed remote status (to indicate to the remote end it knows about that remote status change) or when the remote status is Unknown. + +## C.4 Bonding aggregation control protocol frame formats + +The bonding control engine transmits and receives frames over a PAF via the standard MII interface to the PAF as shown in Figure C.1. Bonding aggregation control protocol PDUs must therefore conform to the standard definition of an Ethernet frame. + +This clause describes the format in which BCEs communicate information in the BACPDU. + +#### C.4.1 Slow protocol format + +BACPDU are in fact an instance of an IEEE 802.3 slow protocol (see Annex 43B of [IEEE 802.3-2005]). ITU has been allocated an organizationally unique identifier (OUI), and BACP is a subtype allocated from that ITU OUI. BACP frames are subject to pause frames, i.e., stop and resume their transmission with pause frames just like other data or protocol traffic. + +It is the responsibility of the BCE to ensure that the BACPDU conform to the transmission rate requirements of slow protocols. No more than ten BACPDU can be sent over any PAF in one second. BACPDU can, in general, be sent immediately upon status changes as reflected in the earlier state descriptions, but must still overall live within the ten BACPDU-per-second limitation imposed by the slow protocols encapsulation. + +The BACPDU frame content is shown in Figure C.11. A BACPDU shall be padded to meet the minimum frame size restrictions for Ethernet frames. + +| | +|-------------------------| +| BACP PDU header | +| Variable number of TLVs | +| Ethernet FCS | + +**Figure C.11 – Generic BACPDU content** + +BACPDUs consist of a fixed BACPDUs header followed by a variable number of TLVs. A more detailed look at the BACPDUs header is given in Figure C.12. + +| | +|-----------------------------------------| +| Destination MAC
01:80:C2:00:00:02 | +| Source MAC
(local) | +| Slow protocols
Ethertype = 0x8809 | +| Organization specific
subtype = 0x0A | +| ITU OUI = 0x0019A7 | +| ITU subtype = 0x01
(BACP) | +| BACP version = 0x01 | +| BACP timestamp
(32-bits) | + +**Figure C.12 – BACP header – Slow protocols subtype** + +The fields in the BACP header (beyond the fixed MAC header) are: + +- BACP version. The BACP version number must be set to 0x01 on transmit. BACP frames received with version numbers other than 0x01 must be discarded. +- BACP timestamp. The BCE may choose to timestamp some or all BACPDUs. When timestamps are not in use, this field is all zeros (0x00000000). When timestamps are in use, this field contains the value of a local clock expressed in 0.1-ms units. + +Each TLV contains a one-octet type field and a one-octet length field, followed by the value parameter. The length field includes the length of the entire TLV, including the type and length fields. The rules for processing TLVs are as follows: + +- 1) Detection of the TLV type NULL TLV indicates that there are no additional TLVs to parse. The length and value of the NULL TLV can be ignored. +- 2) Other TLVs with lengths 0x00 or 0x01 must be ignored and considered invalid. The BACP frame should be considered to have no additional TLVs after the detection of a TLV of length 0x00 or 0x01. +- 3) TLVs with unknown types should be ignored. +- 4) If the length of the TLV is less than expected for a known type, the TLV should be ignored. +- 5) If the length of a TLV is greater than expected for a known type, the TLV is assumed to have been extended and the expected fields of that TLV can be processed in the expected locations. The data in the area greater than the expected length but less than the actual length can be ignored. +- 6) If a length field indicates that the TLV extends beyond the length of the actual frame, the TLV should be ignored and the frame discarded. + +The TLV types defined in this annex are given in Table C.1. A BACPDUs shall contain, at a minimum, a local info TLV and a remote info TLV and shall be terminated by a NULL TLV. + +**Table C.1 – Defined TLV types** + +| TLV type | TLV name | TLV length | TLV description | +|----------|---------------------------|------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 0x00 | NULL TLV | 0 | End-of-TLVs marker. | +| 0x01 | Local info TLV | 24 | Contains the status of all PMEs related to this PAF as well as the group ID for the PME as known by the transmitting BCE. | +| 0x02 | Remote info TLV | 24 | This TLV contains a copy of last received local info TLV from the remote BCE (thus reflecting a copy of the information back to the remote BCE, allowing the remote BCE to confirm that its information had been received). | +| 0x03 | Assignment TLV | 8 | Contains the stream ID and PME ID for this PME. The stream ID has context across all PAFs, while the PME ID is relative only to the current PAF. | +| 0xFF | Organization-specific TLV | N/A | Organization-Specific TLV. | + +### **C.4.2 BACP TLVs** + +This clause details the format of the TLVs that may be contained in a BACPDUs. If a remote GID, a remote PME ID or a remote stream ID is not known, then that field shall be set to all ones. + +##### **C.4.2.1 NULL TLV** + +The NULL TLV is used to indicate that this is the last TLV in the BACPDUs. TLV processing for the frame terminates when this TLV is processed. There is no length or value field for this TLV. + +The NULL TLV is required in every BACPDUs. BACPDUs without NULL TLVs should be discarded. + +##### **C.4.2.2 Local info TLV** + +The local info TLV contains two pieces of information as known by the local (transmitting) BCE: the group ID (see clause C.3.1.1) and PME status array (see clause C.3.1.5). These are, respectively, 6-octet and 16-octet fields. + +| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +|-------------|---|---|---|---|---|------------------------------|---|----------|---|---|---|---|---|---|---|---|---|---|---|----------|---|---|---|---|---|---|---|---|---|---|---|--|--|--|--|--|--|--|--|--|--|--| +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | | | | | | | | | | | | +| Type = 0x01 | | | | | | | | Len = 24 | | | | | | | | | | | | group ID | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | Group ID (continued) | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | PME status array | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | PME status array (continued) | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | PME status array (continued) | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | PME status array (continued) | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | + +Each PME known to this PAF has its status reflected in the PME status array. The PME assigned PME ID 'n' has its status carried in the nth location of the PME status array (n = 0..31), where each location identifies a 4-bit status field. + +##### C.4.2.3 Remote info TLV + +The remote info TLV is included to echo back to a BCE the values that the remote BCE is receiving from the local BCE on this PAF. This TLV is used to confirm that local status changes communicated by one BCE have been received by the other BCE. + +This TLV has the same format as the local info TLV. + +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | +|-------------|---|---|---|---|---|---|---|----------|---|-------------------------------------|---|---|---|---|---|---|---|-----------------|---|---|---|---|---|---|---|---|---|---|---|---|---| +| Type = 0x02 | | | | | | | | Len = 24 | | | | | | | | | | Remote group ID | | | | | | | | | | | | | | +| | | | | | | | | | | Remote group ID (continued) | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | Remote PME status array | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | Remote PME status array (continued) | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | Remote PME status array (continued) | | | | | | | | | | | | | | | | | | | | | | +| | | | | | | | | | | Remote PME status array (continued) | | | | | | | | | | | | | | | | | | | | | | + +When no information has been received from the remote BCE on this PAF, all remote PME status values are set to Unknown, i.e., the remote PME status array is returned as all zeros. + +##### C.4.2.4 Assignment TLV + +The assignment TLV is used to associate a stream with a relative PME ID within a specific PAF. The assignment TLV contains four values, the local stream ID and PME ID of that stream within this PAF, and the remote stream ID and PME ID of that stream within this PAF. It is used to communicate the association of these four values to the remote BCE. The format of the assignment TLV is given below. + +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | +|------------------|---|---|---|---|---|---|---|---------|---|---|---|---|---|---|---|--------|---|-----------|---|---|---|---|---|---|---|---------------|---|---|---|---|---| +| Type = 0x03 | | | | | | | | Len = 8 | | | | | | | | | | Stream ID | | | | | | | | | | | | | | +| Remote stream ID | | | | | | | | | | | | | | | | PME ID | | | | | | | | | | Remote PME ID | | | | | | + +The assignment TLV is included in a BACPDUs in two situations. First, whenever the PME is first initializing with BACP (see clause C.3.2.1). Second, when a PME is being transferred into a new PAF, the assignment TLV is used in the BACPDUs on that new PAF to associate a known stream with a PME ID for that PAF. + +##### C.4.2.5 Organization-specific TLV + +Organizations may extend this protocol by including additional TLV information in BACPDUs. This Recommendation does not restrict or control organization-specific TLVs – they are controlled by the organization identified within the TLV. The format of organization-specific TLVs is given below: + +| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | +|-------------|---|---|---|---|---|---|---|---------|---|------------------------------|---|---|---|---|---|---|---|-----|---|---|---|---|---|---|---|---|---|---|---|---|---| +| Type = 0xFF | | | | | | | | Len = ? | | | | | | | | | | OUI | | | | | | | | | | | | | | +| OUI (cont) | | | | | | | | | | Specified by organization... | | | | | | | | | | | | | | | | | | | | | | + +Organization-specific TLVs can be included in any BACPDUs. They can be of any length. An OUI is used to identify the organization that specified the syntax and semantics of the rest of the value field of the TLV. + +# Annex D + +## Ethernet bonding with DTU encapsulation + +(This annex forms an integral part of this Recommendation.) + +The specific normative requirements for data transfer unit (DTU) encapsulation are contained in the applicable ITU-T Recommendation for the underlying transport technology such as [b-ITU-T G.9701] (G.fast). The exception to clause 61.2.2.5 of [IEEE 802.3-2005] defined in clause 6.2.3 of this Recommendation is extended as follows (at the end of the paragraph before the Note): "The receiving PCS shall be able to handle a total differential delay of 1 623 000 bit times (approximately 1.6 ms at 1 Gbit/s) without the need to stop traffic flow on any of the bonded lines in order to achieve reliable bonding operation. The receiving PCS shall be able to apply flow control to the underlying transport technology when the PCS receive buffer is full." + +NOTE – Some implementations may be able to handle a total differential delay higher than 1 623 000 bit times and achieve higher bonding efficiency. + +The exception to clause 61.2.2 (PME aggregation functions) of IEEE 802.3-2005 defined in clause 6.2.2 of this Recommendation is extended as follows: "Instead of adding a 16-bit Frame Check Sequence, known as the TC-CRC, to each fragment by the TPS-TC sub-layer, fragments are encapsulated into DTUs and a 32-bit Frame Check Sequence, known as ECS, is added to each DTU by the TPS-TC sub-layer (see clause 8.2 of [b-ITU-T G.9701])." + +# Bibliography + +- [b-ITU-T G.9701] Recommendation ITU-T G.9701 (2014), *Fast access to subscriber terminals (G.fast) – Physical layer specification.* + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9980-201211-I_PDF-E/raw.md b/marked/G/T-REC-G.9980-201211-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..f2cc38a8375d9e9796baffa9f851d9ecc72f974d --- /dev/null +++ b/marked/G/T-REC-G.9980-201211-I_PDF-E/raw.md @@ -0,0 +1,876 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9980** + +(11/2012) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – In premises networks + +--- + +**Remote management of customer premises +equipment over broadband networks – +Customer premises equipment WAN +management protocol** + +Recommendation ITU-T G.9980 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## **Recommendation ITU-T G.9980** + +# **Remote management of customer premises equipment over broadband networks – Customer premises equipment WAN management protocol** + +## **Summary** + +Recommendation ITU-T G.9980 defines requirements for the remote management of networked devices by a service provider in a consumer's home. It provides an overview of, and the necessary normative references to, a family of technical specifications. It describes how the various technical specifications in this family are related. A glossary of the terms and definitions used in the technical specifications is included in clauses 3 and 4. + +## **History** + +| Edition | Recommendation | Approval | Study Group | +|---------|----------------|------------|-------------| +| 1.0 | ITU-T G.9980 | 2012-11-23 | 15 | + +## **Keywords** + +CWMP, TR-069. + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2013 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|----------------------------------------------------------|------| +| 1 Scope ..... | 1 | +| 2 References..... | 3 | +| 3 Definitions ..... | 3 | +| 3.1 Terms defined elsewhere ..... | 3 | +| 3.2 Terms defined in this Recommendation..... | 3 | +| 4 Abbreviations and acronyms ..... | 4 | +| 5 Conventions ..... | 4 | +| 6 Remote management of CPE over broadband networks ..... | 4 | +| 6.1 Elements of the CPE WAN management protocol ..... | 4 | +| 6.2 Data models ..... | 8 | +| Bibliography..... | 21 | + +# **Introduction** + +The basis of this Recommendation is the Broadband Forum CPE WAN management protocol (CWMP), commonly referred to as TR-069. + +The protocol is intended for communication between a CPE and an auto-configuration server (ACS). The CPE WAN management protocol defines a mechanism that encompasses secure auto-configuration of a CPE, and also incorporates other CPE management functions into a common framework. + +TR-069 specifies the generic requirements of the management protocol, and methods that can be applied to any TR-069 CPE. Other Broadband Forum technical reports (TRs) specify the managed objects, or data models, for specific types of devices or services. + +The protocol may be used to manage various types of CPE, including stand-alone routers and LAN-side client devices. It is agnostic to the specific access medium utilized by the service provider, although it does depend on IP-layer connectivity having first been established by the device. + +# Remote management of customer premises equipment over broadband networks – Customer premises equipment WAN management protocol + +# 1 Scope + +This Recommendation defines the requirements for the remote management of networked devices by a service provider in a consumer's home. It provides an overview of, and the necessary normative references to, a family of technical specifications (see Figure 1). It describes how the various technical specifications in this family are related. + +CPE such as G-PON ONUs may be partially managed by OMCI, as specified in [b-ITU-T G.988]. [b-ITU-T G.988] defines options for shared management of such devices. These options, and the OMCI management of CPE, are outside the scope of this Recommendation. + +The protocol is intended to provide flexibility in the connectivity model. + +- The protocol allows both CPE and ACS initiated connection establishment, avoiding the need for a persistent connection to be maintained between each CPE and an ACS. +- The functional interactions between the ACS and CPE should be independent of which end initiated the establishment of the connection. In particular, even where ACS initiated connectivity is not supported, all ACS initiated transactions should be able to take place over a connection initiated by the CPE. +- The protocol allows one or more ACSs to serve a population of CPE. Each CPE can only be associated with one ACS, while each ACS may be associated with one or more service providers. However, a single physical device may present more than one logical CPE device, each of which may be associated with a different ACS. +- The protocol provides mechanisms for a CPE to discover the appropriate ACS for a given service provider. +- The protocol provides mechanisms to allow an ACS to securely identify a CPE and associate it with a user/customer. + +Processes to support such association support models that incorporate user interaction as well as those that are fully automatic. + +The protocol allows an ACS to control and monitor various parameters associated with a CPE. The mechanisms provided to access these parameters are designed with the following premises. + +- Different CPE may have differing capability levels, implementing different subsets of optional functionality. Additionally, an ACS may manage a range of different device types delivering a range of different services. As a result, an ACS must be able to discover the capabilities of a particular CPE. +- An ACS must be able to control and monitor the current configuration of a CPE. +- Other entities besides an ACS may be able to control some parameters of a CPE's configuration (e.g., via LAN-side auto-configuration). As a result, the protocol must allow an ACS to account for external changes to a CPE's configuration. The ACS should also be able to control which configuration parameters can be controlled via means other than by the ACS. +- The protocol should allow vendor-specific parameters to be defined and accessed. + +The protocol is intended to minimize implementation complexity, while providing flexibility in trading off complexity vs. functionality. The protocol incorporates a number of optional components that come into play only if specific functionality is required. The protocol incorporates existing standards where appropriate, allowing leverage of off-the-shelf implementations. + +The protocol is agnostic to the underlying access network. + +The protocol is also extensible. It includes mechanisms to support future extensions to the standard, as well as explicit mechanisms for vendor-specific extensions. + +![Diagram of CPE WAN management protocol architecture showing ACS, Residential gateway, and various connected devices (IP STB, Storage, Femto access point, VoIP, Voice ATA, PC) with associated technical specifications.](d0abac95583b52a3b35f74a215567334_img.jpg) + +The diagram illustrates the CPE WAN management protocol architecture. On the left, an **ACS** (Auto-configuration server) is connected to a **Residential gateway**. The ACS is associated with three technical specifications in double-lined rectangles: **TR-157 component objects for CWMP**, **TR-069 CPE WAN management protocol**, and **TR-143: Throughput performance testing**. The Residential gateway is associated with **TR-181i2: Device data model for TR-069** in a double-lined rectangle. To the right of the gateway, various devices are connected, each with associated technical specifications in single-lined rectangles: + + +- IP STB** (IP Set-Top Box) is associated with **TR-104: VoIP**, **TR-135: STB**, and **TR-140: storage**. +- Storage** is associated with **TR-196: Femto cell**. +- Femto access point** is associated with **TR-106: Common data model template**. +- VoIP** (Voice over IP) is associated with **TR-106: Common data model template**. +- Voice ATA** (Analog Telephone Adapter) is associated with **TR-106: Common data model template**. +- PC** (Personal Computer) is associated with **TR-106: Common data model template**. + + At the bottom, a box lists the underlying networking technologies: **G.hn (ITU-T G.996x series)**, **Ethernet**, **Wireless**, and **Other home networking technologies**. The diagram is labeled **G.9980(12)\_F01** in the bottom right corner. + +Diagram of CPE WAN management protocol architecture showing ACS, Residential gateway, and various connected devices (IP STB, Storage, Femto access point, VoIP, Voice ATA, PC) with associated technical specifications. + +Technical reports for CWMP and data models (see clauses 6.1 and 6.2) are shown in double line rectangles. + +Technical reports that define service data models (see clauses 6.2.1) are shown in rectangles. + +**Figure 1 – CPE WAN management protocol and its related technical specifications** + +Any protocol describing remote configuration or software-/firmware modification of CPEs must provide the capabilities to comply with all applicable national and regional laws, regulations and policies. The implementation of mechanisms to ensure the explicit endorsement of the customer by means of opt-in permissions before remotely initiating any procedures on the CPE may be required by some specific national and regional laws, regulations and policies. Implementers and users of the described CWMP shall comply with all applicable national and regional laws, regulations and policies. + +Implementers and users of all ITU-T Recommendations, including ITU-T G.9980 and the underlying techniques, shall comply with all applicable national and regional laws, regulations and policies. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [BBF TR-069] Broadband Forum TR-069 Amendment 2 (2007), *CPE WAN Management Protocol v1.1*. +<[http://www.broadband-forum.org/technical/download/TR-069\\_Amendment-2.pdf](http://www.broadband-forum.org/technical/download/TR-069_Amendment-2.pdf)> +- [BBF TR-104] Broadband Forum TR-104 (2005), *DSLHome Provisioning Parameters for VOIP CPE*. +<> +- [BBF TR-106] Broadband Forum TR-106 Amendment 4 (2010), *Data Model Template for TR-069-Enabled Devices*. +<[http://www.broadband-forum.org/technical/download/TR-106\\_Amendment-4.pdf](http://www.broadband-forum.org/technical/download/TR-106_Amendment-4.pdf)> +- [BBF TR-135] Broadband Forum TR-135 (2007), *Data Model for a TR-069 Enabled STB*. +<> +- [BBF TR-140] Broadband Forum TR-140 (2007), *TR-069 Data Model for Storage Service Enabled Devices*. +<[http://www.broadband-forum.org/technical/download/TR-140\\_Issue1.1.pdf](http://www.broadband-forum.org/technical/download/TR-140_Issue1.1.pdf)> +- [BBF TR-143] Broadband Forum TR-143 Corrigendum 1 (2008), *Enabling Network Throughput Performance Tests and Statistical Monitoring*. +<[http://www.broadband-forum.org/technical/download/TR-143\\_Corrigendum-1.pdf](http://www.broadband-forum.org/technical/download/TR-143_Corrigendum-1.pdf)> +- [BBF TR-157] Broadband Forum TR-157 Amendment 1 (2009), *Component Objects for CWMP*. +<[http://www.broadband-forum.org/technical/download/TR-157\\_Amendment-1.pdf](http://www.broadband-forum.org/technical/download/TR-157_Amendment-1.pdf)> +- [BBF TR-181 Issue 2] Broadband Forum TR-181 Issue 2 (2010), *Device Data Model for TR-069*. +<[http://www.broadband-forum.org/technical/download/TR-181\\_Issue-2.pdf](http://www.broadband-forum.org/technical/download/TR-181_Issue-2.pdf)> +- [BBF TR-196] Broadband Forum TR-196 (2009), *Femto Access Point Service Data Model*. +<> + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +**3.1.1 customer premises equipment (CPE)** [b-ITU-T Y.101]: End-use system including private network elements connecting the customer applications to the access line. + +**3.1.2 technical report (TR)**: An approved technical specification of the Broadband Forum in accordance with [b-BBF01]. + +## 3.2 Terms defined in this Recommendation + +This Recommendation defines the following term: + +**3.2.1 remote management**: Management of CPE over a WAN by a service provider. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|---------|----------------------------------------------| +| ACS | Auto-Configuration Server | +| CPE | Customer Premises Equipment | +| CWMP | CPE WAN Management Protocol | +| FAP | Femto Access Point | +| FDD | Frequency-Division Duplexing | +| IPTV | Internet Protocol Television | +| NAS | Network Attached Storage | +| NAT | Network Address Translation | +| PVR | Personal Video Recorder | +| QoE | Quality of Experience | +| QoS | Quality of Service | +| RG | Residential Gateway | +| RPC | Remote Procedure Call | +| SIP | Session Initiation Protocol | +| SSL/TLS | Secure Socket Layer/Transport Layer Security | +| STB | Set-Top Box | +| TR | Technical Report | +| UMTS | Universal Mobile Telecommunication System | +| VoIP | Voice over Internet Protocol | +| WAN | Wide Area Network | + +# 5 Conventions + +There are no particular notations, styles, presentations, etc. used within the Recommendation. + +# 6 Remote management of CPE over broadband networks + +This clause lists the elements of the CPE WAN management protocol (see clause 6.1) and the data models for specific devices (see clause 6.2), which constitute a normative part of this Recommendation. + +## 6.1 Elements of the CPE WAN management protocol + +The requirements for the CPE WAN management protocol are defined in [BBF TR-069]. + +It is recognized that service provider policies or local regulations may restrict the use of CPE WAN management and its partner specifications for privacy and security reasons. Such restrictions could encompass one or more of the following: + +- CWMP communications only via mutually authenticated SSL/TLS channels; +- restrictions on the type of CPE to be managed remotely; + +- requirement for explicit individual endorsement by the subscriber, which must take place before remote management is established to retrieve information about the CPE configuration; +- requirement for asking of an explicit endorsement by the subscriber, which must take place before changing the CPE configuration; +- other. + +### **6.1.1 TR-069: CPE WAN management protocol (CWMP)** + +[BBF TR-069] is intended for communication between a CPE and an auto-configuration server (ACS). The CPE WAN management protocol defines a mechanism that encompasses secure auto-configuration of a CPE, and incorporates other CPE management functions into a common framework. + +To aid the technical alignment of the Recommendation with [BBF TR-069], the remainder of this clause (shown within a frame) is structured in accordance with [BBF TR-069]. The numbered titles refer to section numbers in [BBF TR-069] itself. + +#### **1 Introduction** + +The CWMP generic requirements of the management protocol methods may be applied to any CWMP enabled CPE. + +From a purely functional perspective, CWMP supports a variety of functionalities to manage a collection of CPE, including the following primary capabilities: + +- auto-configuration and dynamic service provisioning; +- software/firmware image management; +- status and performance monitoring; +- diagnostics. + +##### **1.2 Positioning in the end-to-end architecture** + +The ACS is a server that resides in the network. It manages devices in or at the subscriber premises via the CPE WAN management protocol. CWMP is agnostic to the specific access medium utilized by the service provider, although it does depend on IP-layer connectivity having been established. + +##### **1.3 Security goals** + +CWMP security is intended to be scalable to match a range of CPE, from very simple to very sophisticated. The security goals are: + +- prevent tampering with the management functions of a CPE or ACS, or transactions that take place between a CPE and ACS; +- provide confidentiality for the transactions that take place between CPE and ACS; +- allow appropriate authentication for each type of transaction; +- prevent theft of service. + +#### **2 Architecture** + +##### **2.1 Protocol components** + +CWMP applications are defined atop a stack that respectively comprises RPC methods, SOAP, HTTP, SSL/TLS, TCP and IP as specified in [BBF TR-069]. + +##### **2.2 Security mechanisms** + +Mechanisms available to CWMP include SSL/TLS and HTTP shared secrets. + +##### **2.3 Architectural components** + +CWMP is designed around the fundamental idea of remotely setting and retrieving named variables, creating and deleting remote objects, and invoking a small set of predefined methods. It builds on this foundation to support auto-discovery, notifications and file transfer mechanisms. + +Standard CWMP information models are specified in clause 6.2 of this Recommendation. The information model may also be extended in vendor-specific ways. + +CWMP sessions may be initiated by either ACS or CPE. When a CPE initializes, it may contact an ACS to obtain part or essentially all of its configuration, possibly even including its firmware load. + +#### **3 Procedures and requirements** + +##### **3.1 ACS discovery** + +The CPE may have a default ACS URL built into its configuration. The CPE may also learn the identity of the ACS through local configuration, or through a DHCP option. DHCP may also provide a provisioning code, to be used by the CPE in further identifying itself to the ACS. The ACS may itself modify the URL to be used by the CPE for subsequent contact with a different ACS. + +If the ACS URL specifies HTTPS, the CPE must use SSL/TLS to establish the session with the ACS. + +##### **3.2 Connection establishment** + +The CPE may initiate a session with the ACS when it initializes, when an ACS-configured periodic or scheduled inform time arrives, when it needs to send a provisioned value or state change notification or to recover a prematurely terminated earlier session. The CPE does not maintain an open session when it has no information to exchange with the ACS. + +The ACS may indirectly initiate a session with the CPE through an HTTP request that the CPE open a session with the ACS. + +##### **3.3 Use of SSL/TLS and TCP** + +SSL/TLS is recommended for all sessions, but not required. If SSL/TLS is used, the CPE must authenticate the ACS through certificate-based authentication. The ACS is also encouraged to authenticate the CPE. + +Other paragraphs in section 3 describe the details of message coding (SOAP), session establishment, operation and termination and file transfer operations. Additional authentication requirements are defined, including ACS HTTP authentication of CPE, if CPE authentication has not already been performed during the SSL/TLS negotiation. + +###### **Annex A – RPC methods** + +The data types and messages defined for CWMP remote procedure calls (RPC) are defined in Annex A of [BBF TR-069]. As well as the syntax of each message and its response, the annex specifies any special behavioural constraints that may apply to either ACS or CPE. + +A generic XML schema is included as part of this annex. + +###### **Annex B – Removed** + +(Removed from this edition of TR-069.) + +###### **Annex C – Signed vouchers** + +###### **Annex D – Web identity management** + +###### **Annex E – Signed package format** + +###### **Annex F – Device-gateway association** + +CWMP can be used to remotely manage CPE devices that are connected via a LAN through a gateway. When an ACS manages both a device and the gateway through which the device is connected, it can be useful for the ACS to be able to determine the identity of that particular gateway. + +The procedures defined in this annex allow an ACS to determine the identity of the gateway through which a given device is connected. The mechanism relies on the use of DHCP by both the device and the gateway. + +In an exemplary use case, an ACS establishing QoS for a particular service might need to provision both the device as well as the gateway through which that device is connected. To do the latter, the ACS would need to determine the identity of that particular gateway. + +To support this feature, both the gateway and device are expected to be managed via CWMP, and both managed by the same ACS, or by distinct ACSs that are appropriately coupled. + +###### **Annex G – Connection request via NAT gateway** + +Network address translation (NAT) in a gateway isolates the LAN-side IP address space from the WAN-side IP space. CPE behind a NAT gateway can use the previously defined methods to initiate sessions, but the procedures defined in this annex are needed for the ACS to be able to request a connection from the CPE. The NAT gateway does not need to support CWMP. + +#### **6.1.2 Auto-configuration and dynamic service provisioning** + +CWMP allows an ACS to provision a CPE or collection of CPE based on a variety of criteria. + +The provisioning mechanism allows CPE provisioning at the time of initial connection to the broadband access network, and the ability to re-provision or re-configure at any subsequent time. This includes support for asynchronous ACS-initiated re-provisioning of a CPE. + +The identification mechanisms included in the protocol allow CPE provisioning based either on the requirements of each specific CPE, or on collective criteria such as the CPE vendor, model or software version. + +The protocol also provides optional tools to manage the CPE-specific components of optional applications or services for which an additional level of security is required, such as those involving payments. + +The provisioning mechanism allows straightforward future extension to allow provisioning of services and capabilities not yet included in this version. + +#### **6.1.3 Software/firmware image management** + +CWMP provides a framework for managing the downloading of CPE software/firmware image files. The protocol provides mechanisms for version identification, file download initiation (ACS initiated downloads and optional CPE initiated downloads) and notification of the ACS of the success or failure of a file download. + +#### **6.1.4 Status and performance monitoring** + +CWMP provides support for a CPE to make available information that the ACS may use to monitor the CPE's status and performance statistics. It also defines a set of mechanisms that allow the CPE to actively notify the ACS of changes to its state. [BBF TR-143] facilitates throughput testing to be able to assess the subscribers experience in terms of broadband speed. + +#### **6.1.5 Diagnostics** + +CWMP provides support for a CPE to make available information that the ACS may use to diagnose and resolve connectivity or service issues as well as the ability to execute defined diagnostic tests. + +#### **6.1.6 Security** + +CWMP is designed to provide a high degree of security. The security model is also designed to be scalable. It allows for basic security to accommodate less robust CPE, while allowing greater security for CPE that can support more advanced security mechanisms. The security goals of the CPE WAN management protocol are as follows: + +- prevent tampering with the management functions of a CPE or ACS, or the transactions that take place between a CPE and ACS; +- allow for mutual strong authentication of CPE and ACS; +- provide confidentiality for transactions between CPE and ACS; +- allow appropriate authentication for each type of transaction; +- prevent theft of service. + +## **6.2 Data models** + +A key concept within CWMP is that of a data model. A data model provides objects and parameters that can be acted on by the CWMP generic method calls. These objects and parameters expose configuration, diagnostics or status data for various types of services and devices. For example, the data model for a VoIP device exposes parameters related to SIP configuration, among other VoIP- + +related capabilities. Data models define a superset of functionality that could be managed for a particular device or service; devices implement the portions of the data models that are relevant for their specific functionality. + +The requirements for the CPE WAN management data models are defined in [BBF TR-106], [BBF TR-143], [BBF TR-157], [BBF TR-181 Issue 2], [BBF TR-104], [BBF TR-135], [BBF TR-140] and [BBF TR-196]. + +[BBF TR-106] defines generic information for defining CWMP data models, including requirements around hierarchy, rules for obsolescence and deprecation, data types and the CWMP-DM XML schema, which is used for defining all data models. + +CPE, such as residential gateways (RG), set-top boxes (STB) and network attached storage (NAS) devices, are provisioned and managed using a common set of parameters, which make the device recognizable from the network ACS and allow auto-provisioning and ongoing management. + +Technical reports that establish these parameters are: + +- [BBF TR-181 Issue 2]: Device data model for TR-069 +- [BBF TR-157]: Component objects for CWMP +- [BBF TR-143]: Enabling network throughput performance tests and statistical monitoring + +Technical reports that define service data models are: + +- [BBF TR-104]: DSLHome provisioning parameters for VOIP CPE +- [BBF TR-135]: Data model for a TR-069 enabled STB +- [BBF TR-140]: TR-069 data model for storage service enabled devices +- [BBF TR-196]: Femto access point service data model + +### **6.2.1 TR-181 Issue 2: Device data model for TR-069** + +[BBF TR-181 Issue 2] defines version 2 of the TR-069 device data model. The data model applies to all types of TR-069-enabled devices, including end devices, Internet gateway devices and other network infrastructure devices. It represents a next generation evolution that supersedes both [b-BBF TR-181 Issue 1] (not included in the Recommendation) and [b-BBF TR-098] amendment 2 (not included in the Recommendation). Legacy installations may continue to make use of the InternetGatewayDevice:1 and Device:1 data models, which are still valid. + +NOTE – The evolution to Device:2 was necessary in order to resolve some fundamental limitations in the InternetGatewayDevice:1 data model, which proved to be inflexible and caused problems in representing complex device configurations. However, in defining this next generation data model, care has been taken to ensure that all InternetGatewayDevice:1 and Device:1 functionality has been covered. + +The Device:2 data model defined in [BBF TR-181 Issue 2] comprises a set of data objects covering things like basic device information, time-of-day configuration, network interface and protocol stack configuration, routing and bridging management and diagnostic tests. It also defines a baseline profile that specifies a minimum level of data model support. + +The cornerstone of the Device:2 data model is the interface stacking mechanism. Network interfaces and protocol layers are modelled as independent data objects that can be stacked, one on top of the other, into whatever configuration a device might support. + +To aid the technical alignment of the Recommendation with [BBF TR-181 Issue 2], the remainder of this clause (shown inside a frame) is structured in accordance with [BBF TR-181 Issue 2]. The numbered titles refer to section numbers in [BBF TR-181 Issue 2] itself. + +#### 4 Architecture + +##### 4.1 Interface layers + +This Technical Report models network interfaces and protocol layers as independent data objects, generally referred to as interface objects (or interfaces). Interface objects can be stacked, one on top of the other, using path references in order to dynamically define the relationships between interfaces. + +The interface object and interface stack are concepts inspired by [b-IETF RFC 2863]. + +Within the Device:2 data model, interface objects are arbitrarily restricted to definitions that operate at or below the IP network layer (i.e., layers 1 through 3 of the OSI model). However, vendor specific interface objects MAY be defined which fall outside this restricted scope. + +##### 4.2 Interface objects + +An interface object is a type of network interface or protocol layer. Each type of interface is modelled by a Device:2 data model table, with a row per interface instance (e.g., IP.Interface.{i} for IP Interfaces). + +Each interface object contains a core set of parameters and objects, which serves as the template for defining interface objects within the data model. Interface objects can also contain other parameters and sub-objects specific to the type of interface. + +##### 4.3 InterfaceStack table + +Although the interface stack can be traversed via LowerLayers parameters (as described in section 4.2.1 *Lower Layers*), an alternate mechanism is provided to aid in visualizing the overall stacking relationships and to quickly access objects within the stack. + +The InterfaceStack table is a Device:2 data model object, namely *Device.InterfaceStack.{i}*. This is a read-only table whose rows are auto-generated by the CPE based on the current relationships that are configured between interface objects (via each interface instance's LowerLayers parameter). Each table row represents a "link" between a higher-layer interface object (referenced by its HigherLayer parameter) and a lower-layer interface object (referenced by its LowerLayer parameter). This means that an InterfaceStack table row's HigherLayer and LowerLayer parameters will always both be non-null. + +NOTE – As a consequence, interface instances that have been stranded will not be represented within the InterfaceStack table. It is also likely that multiple, disjoint groups of stacked interface objects will coexist within the table (for example, each IP interface will be the root of a disjoint group; unused "fragments", e.g., a secondary DSL channel with a configured ATM PVC that is not attached to anything above, will linger if they remain interconnected; and finally, partially configured "fragments" can be present when an interface stack is being set up). + +#### 5 Parameter definitions + +The normative definition of the Device:2 data model is split between several DM instance documents (see [BBF TR-069] Annex A). Table 3 lists the Device:2 data model versions and DM instances that had been defined at the time of writing. It also indicates the corresponding technical reports and gives links to the associated XML and HTML files. The TR-181i2 XML document defines the Device:2 model itself, and imports additional components from the other XML documents listed. The TR-181i2 HTML document is a report generated from the XML files, and lists the entire Device:2 data model in human-readable form. + +##### Annex A – Bridging and queuing + +This annex defines the queuing and bridging model (the packet classification, the queuing and scheduling, and bridging), the default layer 2/3 QoS mapping and URN definitions for app and flow tables (App ProtocolIdentifier, Flow Type and Flow TypeParameters). + +### 6.2.2 TR-157: Component objects for CWMP + +[BBF TR-157] defines component objects for use in CWMP managed devices for all root data models. A component object is defined as an object and its contained parameters are intended for use in any applicable CWMP root data model. The object(s) may reside at the top level or an appropriate sub-object level. + +To support the functionality defined in [BBF TR-157], an extension to the device data model and InternetGatewayDevice data model is specified in Table 1 of [BBF TR-157]. For the device data model, this extension is considered part of Device:1.4 (version 1.4 of the device data model), which extends version 1.3 of the device data model defined in TR-157 Issue 1. For the InternetGatewayDevice data model, this extension is considered part of InternetGatewayDevice:1.6 (version 1.6 of the InternetGatewayDevice data model), which extends version 1.5 of the InternetGatewayDevice data model defined in TR-157 Issue 1. + +### **6.2.3 TR-143: Enabling network throughput performance tests and statistical monitoring** + +[BBF TR-143] defines an active monitoring test suite that can be leveraged by network service providers to monitor and/or diagnose the state of their broadband network paths serving populations of subscribers who have TR-069 compliant CPE. Active monitoring supports both network initiated diagnostics and CPE initiated diagnostics for monitoring and characterization of service paths in either an ongoing or on-demand fashion. These generic tools provide a platform for the validation of QoS objectives and service level agreements. + +To aid the technical alignment of the Recommendation with [BBF TR-143], the remainder of this clause (shown inside a frame) is structured in accordance with [BBF TR-143]. The numbered titles refer to section numbers in [BBF TR-143] itself. + +#### **4 Active monitoring** + +Active monitoring is the concept of introducing dummy TCP or UDP traffic into a network, in this case, a broadband access network that includes TR-069-enabled CPE, for the purpose of evaluating QoS. Test traffic may originate in the network or at CPE that supports [BBF TR-143]. + +#### **5 Parameter definitions** + +Section 5 defines the specific syntax and semantics of the parameters of a VoIP service. Parameters are grouped into packages, which are then further collected into profiles for various applications in section 7. + +#### **6 Notification requirements** + +#### **7 Profile definitions** + +##### **7.1 Notation** + +##### **7.2 Download profile** + +The download profile configures CPE to execute a download test and to record the results. Ethernet priority and DSCP fields may be configured as part of the profile. + +##### **7.3 DownloadTCP profile** + +The download TCP profile extends the download profile to record TCP request and response times, when the download uses TCP. + +##### **7.4 Upload profile** + +The upload profile configures CPE to execute an upload test and to record the results. Ethernet priority and DSCP fields may be configured as part of the profile. + +##### **7.5 UploadTCP profile** + +The upload TCP profile extends the upload profile to record TCP request and response times, when the upload uses TCP. + +##### **7.6 UDPEcho profile** + +The UDP echo profile configures the CPE to execute a UDP echo test. + +##### **7.7 UDPEchoPlus profile** + +The UDP echoplus profile extends the UDP echo profile by adding an echo-plus enabling parameter. + +##### **Appendix A – Theory of operations** + +###### **A.1 UDP echo plus** + +The UDP echoplus feature is an extension to the ordinary ICMP echo function. It allows both one way and round-trip measurements of packet performance. It is processed according to its DSCP or Ethernet priority markings, which makes a better measure of performance as seen by the subscriber. + +###### **A.2 DownloadDiagnostics utilizing FTP transport** + +This test is the FTP transfer of a test file from the test server to the CPE. It records the number of bytes received and several time stamps that allow evaluation of download performance. + +###### **A.3 UploadDiagnostics utilizing FTP transport** + +These tests are similar to the download test. + +###### **A.4 DownloadDiagnostics utilizing HTTP transport** + +These tests are similar to the corresponding FTP download test. + +###### **A.5 UploadDiagnostics utilizing HTTP transport** + +These tests are similar to the corresponding FTP upload test. + +### **6.2.4 TR-104: DSLHome provisioning parameters for VOIP CPE** + +[BBF TR-104] defines the data model for provisioning of a voice over IP (VoIP) CPE device by an auto-configuration server (ACS) using the mechanism defined in [BBF TR-069]. + +To aid the technical alignment of the Recommendation with [BBF TR-104], the remainder of this clause (shown inside a frame) is structured in accordance with [BBF TR-104]. The numbered titles refer to section numbers in [BBF TR-104] itself. + +#### 1 Introduction + +TR-104: + +- accommodates VoIP devices that are either embedded in an Internet gateway device or stand alone as independent devices; +- accommodates VoIP devices that support multiple distinct VoIP services, each potentially with multiple distinct lines; +- supports the use of both SIP and MGCP signalling protocols; +- supports various types of VoIP CPE including VoIP endpoints, SIP outbound proxies and SIP back-to-back user agents. + +#### 2 Architecture + +[BBF TR-104] defines a VoiceService as the container associated with the provisioning objects for VoIP CPE. In the context of [BBF TR-106], the VoiceService object defined in [BBF TR-104] is a service object. Individual CPE devices may contain zero or more instances of the VoiceService object. The presence of more than one VoiceService object might be appropriate, for example, where a CPE device serves as a management proxy for other non-TR-069 capable VoIP CPE. For example, an Internet gateway device might serve as a management proxy for one or more non-TR-069 capable VoIP phones. + +Each VoiceService object contains one or more VoiceProfile objects. A VoiceProfile corresponds to one or more phone lines that share the same basic configuration. Each VoiceProfile object contains one or more line objects, each of which represents a single distinct phone line. + +The VoiceProfile object allows a multi-line voice device to group lines with common characteristics under a single profile. By allowing more than one VoiceProfile, the model allows a single multi-line voice device to have groups of lines that are configured differently from others. One possible use of this structure could be to associate distinct groups of lines with completely separate service providers, each with distinct VoIP servers and configuration requirements. Another possible use could be to distinguish between different levels of service from a single service provider. For example, a single device could provide some consumer lines plus some business lines, each associated with a distinct VoiceProfile, and distinguished by their quality characteristics. + +#### 3 VoiceService version 1.0 data model + +Section 3 defines the specific syntax and semantics of the parameters of a VoIP service. Parameters are grouped into packages, which are then further collected into profiles for various applications in section 4. + +#### 4 Profile definitions + +##### 4.1 Notation + +##### 4.2 Endpoint profile + +The endpoint profile collects parameters that are appropriate to a VoIP endpoint into several groups. The capabilities group includes bounds on choice of codec and bit rate, the number of simultaneous sessions, the available signalling protocols, fax and modem detection and pass-through, numbering plan, tone, ringing and button map customization. The voice profile group is subdivided into several smaller groups, dealing with RTP, line status, the parameters of the codec in use, session timers and far-end addresses, and PM counters. + +The following three profiles contain similar information, but in forms tailored for their separate signalling protocols. + +##### 4.3 SIP endpoint profile + +The SIP endpoint profile extends the endpoint profile with specific parameters of importance to SIP signalling, specifically including SIP proxy, registration and subscriber authentication information. + +##### 4.4 MGCP endpoint profile + +The MGCP endpoint profile extends the endpoint profile with parameters of importance to MGCP signalling. Specifics include identity and registration information of the agent and the local user. + +##### **4.5 H323Endpoint profile** + +The H323 endpoint profile extends the endpoint profile with parameters of importance to ITU-T H.323 signalling. Specifics include identity and registration information of the gatekeeper and the local user. + +##### **4.6 TAEndpoint profile** + +The TA endpoint profile is intended to be used by a terminal endpoint. It extends the basic endpoint profile with lists of the associated physical ports and their identifiers that share the same parameters. + +##### **Appendix A – Facility actions** + +Appendix A defines the various VoIP signalling actions that can be triggered by subscriber dial plan prefixes or telephone set pushbuttons. Examples include activation or deactivation of features such as call forwarding, calling line identification, selective ringing and the like. Other actions include, for example, switching between multiple calls on hold. + +##### **Appendix B – Downloading tone and ringer files** + +Appendix B describes the details of using the TR-069 file download feature for the specific purpose of downloading VoIP tone and ringer files. + +### **6.2.5 TR-135: Data model for a TR-069 enabled set-top box** + +[BBF TR-135] provides the specifications for remote management of digital television (IPTV or broadcast) functionality on STB devices via CWMP. Access to network and PVR content is managed by an IPTV service platform, and is outside the scope of the ACS. The ACS may perform some initial configuration of a newly installed STB, but its main functions are configuration of STB parameters for trouble management and collection of statistics for QoS/QoE monitoring. Most parameters defined in [BBF TR-135] are therefore read-only to the ACS. + +NOTE – [BBF TR-135] defines the data model for describing a STB device as well as rules regarding notifications on parameter value change. This provides standard data model profiles that would typically be seen while remotely managing a device of this nature. + +To aid the technical alignment of the Recommendation with [BBF TR-135], the remainder of this clause (shown inside a frame) is structured in accordance with [BBF TR-135]. The numbered titles refer to section numbers in [BBF TR-135] itself. + +#### **5 Architecture** + +A set-top box (STB) is modelled as a collection of functions and capabilities, most of which are optional, and most of which can exist in more than one instance. As well as the basic STB infrastructure, the other components are those whose profiles are defined below in section 7. + +#### **6 Parameter definitions** + +Section 6 defines the specific syntax and semantics of the parameters of a STB. Parameters are grouped into packages, which are further collected into profiles for various applications in section 7. + +#### **7 Profile definitions** + +##### **7.1 Notation** + +##### **7.2 Baseline profile** + +The baseline profile provides read-only information about the capabilities of the STB, including the standards it supports and the maximum number of streams of various types that it can support simultaneously. Writeable parameters are limited to mute control and choice of language for audio and subtitle streams. + +##### **7.3 PVR profile** + +The personal video recorder profile returns the status of a possible PVR application. PVR storage is supported through a reference to a storageService defined in [BBF TR-140]. + +##### **7.4 DTT profile** + +The digital terrestrial television profile provides configuration parameters for digital video broadcasting, as well as read-only maintenance and PM parameters. + +##### **7.5 IPTVBaseline profile** + +The IPTV profile provides read-write QoS buffering parameters, and a set of read-only parameters that report the STB's capabilities and current status with regard to IPTV features. + +##### **7.6 RTCP profile** + +The real-time control protocol profile provides simple configuration control (enable, interval setting) and a status report. + +##### **7.7 RTPAVPF profile** + +The RTP real-time feedback profile configures the real-time RTP feedback feature, and reports its current status. + +##### **7.8 IPTVHomeNetwork profile** + +The IPTV home network profile reports status and capabilities of the STB's home network interfaces, as translated from the WAN-side stream. + +##### **7.9 IGMP profile** + +The IGMP profile provides a way to configure IGMP parameters such as VLAN tagging, robustness and reporting interval, as well as read-only status and PM statistics. + +##### **7.10 BasicPerfmon profile** + +The basic PM profile supports configuration of high-level PM parameters, for example, global enable, time and interval reference times, etc. It reports statistics across the STB as a whole, and high-level statistics for the major components at various levels, for example, RTP, MPEG and video decoder. + +##### **7.11 ECPprofile** + +The error correction PM profile reports statistics related to the RTP error correction capability. + +##### **7.12 VideoPerfmon profile** + +The video PM profile reports statistics associated with the quality of video playback. + +##### **7.13 AudioPerfmon profile** + +The audio PM profile reports statistics associated with the quality of audio playback. + +##### **7.14 AudienceStats profile** + +The audience statistics profile collects channel count and time statistics. + +##### **7.15 AnalogOutput profile** + +The analogue output profile reports the STB's capabilities to support external devices such as video displays. + +##### **7.16 DigitalOutput profile** + +The digital output profile reports whether high-bandwidth digital content protection (HDCP) is in use on the particular video output. + +##### **7.17 CA profile** + +The conditional access profile reports the existence of conditional access, which is modelled through a smart card reader. + +##### **7.18 DRM profile** + +The digital rights management profile provides read-only parameters on the current status of media streams in progress. + +##### **Appendix I – Theory of operations** + +This appendix describes a large number of use cases and explains the way in which they employ the STB information model. + +### **6.2.6 TR-140: TR-069 data model for storage service enabled devices** + +[BBF TR-140] allows for a basic storage service to be managed by an ACS. The following is a sample list of support capabilities an ACS can provide using CWMP: + +- basic configuration and set up during device activation (addressed by [BBF TR-140] and [BBF TR-181 Issue 2]); +- user credentials set up and file privilege access (addressed by [BBF TR-140] (folder access)); +- retrieval of device status (addressed by [BBF TR-140] (parameters) and [BBF TR-181 Issue 2]); +- wireless set up (e.g., WEP security) for a storage service device with Wi-Fi access; +- network diagnostics and troubleshooting, e.g., network connectivity to the Internet gateway device and to the Internet (addressed by [TR-181 Issue 2] (connection parameters)). + +NOTE – Not all of these capabilities are handled with this data model; some capabilities are part of the native CWMP protocol and some capabilities are handled via other data models. + +#### **4 Parameter definitions** + +Section 4 defines the specific syntax and semantics of the parameters of a storage device. Parameters are grouped into packages, which are further collected into profiles for various applications in section 6. + +#### **5 Notification requirements** + +#### **6 Profile definitions** + +##### **6.1 Notation** + +##### **6.2 Baseline profile** + +The baseline profile provides read-only information about a storage service, including its storage and access capabilities, physical devices, file systems and top-level folders. Writeable parameters are limited to configuring the storage service's external network identity. + +##### **6.3 User access profile** + +The user access profile allows the configuration of network and local users, together with their access rights and login credentials. + +##### **6.4 Group access profile** + +The group access profile extends the user access profile to user groups, and allows the definition of access privileges at the group level. + +##### **6.5 FTP server profile** + +The FTP server profile configures a possible FTP server associated with the storage service, including its willingness to serve anonymous users. + +##### **6.6 SFTP server profile** + +The SFTP server profile extends the FTP server profile to also configure a possible SFTP server associated with the storage service. + +##### **6.7 HTTP server profile** + +The HTTP server profile configures a possible HTTP server associated with the storage service, including its security policy. + +##### **6.8 HTTPS server profile** + +The HTTPS server profile extends the HTTP server profile to include additional HTTPS parameters. + +##### **6.9 Volume config profile** + +The volume config profile extends the baseline profile to manage logical volume and top-level folder configuration. + +##### **6.10 RAID profile** + +The RAID profile configures storage arrays and reports on the current status and capacity of the array. + +##### **6.11 Folder quota profile** + +The folder quota profile allows the configuration of folder capacity policies, including over-capacity warning threshold. + +##### **6.12 Volume threshold profile** + +The volume threshold profile configures capacity policies at the level of the logical volume. + +##### **6.13 Network server profile** + +The network server profile configures network access protocols that may be used to access the storage + +service remotely. + +#### **7 Use cases** + +The basic purpose of TR-069-managed storage service is to off-load storage management from the subscriber's responsibility. At the same time, some or all of the storage is accessible externally for use by a nomadic subscriber or by external servers such as the ACS itself (software upgrade) or personal video recorder (PVR) storage (see [BBF TR-135]). + +##### **Annex A – Theory of operations** + +Annex A covers details of storage device operation, including removable device management, access security and details of the use cases. + +##### **Annex B – RAID type descriptions** + +Annex B is a tutorial on the various ways in which disks can be combined under the RAID moniker. + +### **6.2.7 TR-196: Femto access point service data model** + +[BBF TR-196] specifies the data model for femto access point (FAP) for remote management using CWMP. The purpose of [BBF TR-196] is to permit an operator to offer a managed femto access service to subscribers. As such, most aspects of the service are controlled by the ACS. + +The scope of this FAP data model is UMTS FDD home nodeB (3G HNB). However, the structure and organization of the data model can be extended to cover other type(s) of FAP devices, based on other radio interface technologies. + +To aid the technical alignment of the Recommendation with [BBF TR-196], the remainder of this clause (shown inside a frame) is structured in accordance with [BBF TR-196]. The numbered titles refer to section numbers in [BBF TR-196] itself. + +#### **4 Data model definition** + +Section 4 defines the specific syntax and semantics of the parameters of a FAP. Parameters are grouped into packages, which are further collected into profiles for various applications in section 5. + +#### **5 Profile definitions** + +TR-196 defines a large number of profiles to group FAP features. A baseline profile specifies configuration details that are expected in any FAP. Additional profiles describe local access policies, security policy, the various wireless protocols that may be supported, and PM, alarm and diagnostics capabilities. + +The list of profiles includes: + +2. Baseline profile +3. ACL profile +4. Local IP access profile +5. REM WCDMA FDD profile +6. REM GSM profile +7. GPS profile +8. Transport SCTP profile +9. Transport real time profile +10. IPSec tunnel profile +11. UMTS baseline profile +12. UMTS self config profile +13. UMTS self config NL in use intra freq cell profile +14. UMTS self config NL in use inter freq cell profile +15. UMTS self config NL in use inter RAT cell profile +16. UMTS cell config baseline profile +17. UMTS cell config advanced profile +18. UMTS cell config freq measurement profile +19. UMTS cell config UE internal measurement profile +20. UMTS cell config NL intra freq cell profile +21. UMTS cell config NL inter freq cell profile +22. UMTS cell config NL inter RAT cell profile +23. Fault management supported alarms profile +24. Fault management active alarms profile +25. Fault management profile event history profile +26. Fault management profile expedited delivery profile +27. Fault management profile queued delivery profile +28. Performance management profile + +# Bibliography + +- [b-ITU-T G.988] Recommendation ITU-T G.988 (2010), *ONU management and control interface (OMCI) specification*. +- [b-ITU-T Y.101] Recommendation ITU-T Y.101 (2000), *Global Information Infrastructure terminology: Terms and definitions*. +- [b-BBF01] Broadband Forum Technical Report Approval Process. +<> +- [b-BBF TR-098] Broadband Forum TR-098 Amendment 2 (2008), *Internet Gateway Device Data Model for TR-069*. +<[http://www.broadband-forum.org/technical/download/TR-098\\_Amendment-2.pdf](http://www.broadband-forum.org/technical/download/TR-098_Amendment-2.pdf)> +- [b-BBF TR-181 Issue 1] Broadband Forum TR-181 Issue 1 (2010), *Device Data Model for TR-069*. +<[http://www.broadband-forum.org/technical/download/TR-181\\_Issue-1.pdf](http://www.broadband-forum.org/technical/download/TR-181_Issue-1.pdf)> +- [b-IETF RFC 2863] IETF RFC 2863 (2000), *The Interfaces Group MIB*. +- Other related documents +- [b-BBF TR-064] Broadband Forum TR-064 (2004), *LAN-side DSL CPE Configuration*. +<> +- [b-BBF TR-68] Broadband Forum TR-68 (2006), *Base Requirements for an ADSL Modem with Routing*. +<[http://www.broadband-forum.org/technical/download/TR-068\\_Issue-3.pdf](http://www.broadband-forum.org/technical/download/TR-068_Issue-3.pdf)> +- [b-BBF TR-122] Broadband Forum TR-122 Amendment 1 (2006), *Base Requirements for Consumer-Oriented Analog Terminal Adapter Functionality*. +<> +- [b-BBF TR-124] Broadband Forum TR-124 (2006), *Functional Requirements for Broadband Residential Gateway Devices*. +<> +- [b-BBF TR-131] Broadband Forum TR-131 (2009), *ACS Northbound Interface Requirements*. +<> +- [b-BBF TR-133] Broadband Forum TR-133 (2005), *DSLHome TR-064 Extensions for Service Differentiation*. +<> +- [b-BBF TR-142 Issue 2] Broadband Forum TR-142 Issue 2 (2010), *Framework for TR-069 enabled PON Devices*. +<[http://www.broadband-forum.org/technical/download/TR-142\\_Issue-2.pdf](http://www.broadband-forum.org/technical/download/TR-142_Issue-2.pdf)> + + + + + +# SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|---------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | General tariff principles | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Terminals and subjective and objective assessment methods | +| Series Q | Switching and signalling | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects and next-generation networks | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.999.1-201902-I_PDF-E/007b053fe94a8348f75128a584503fd0_img.jpg 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a/marked/G/T-REC-G.999.1-201902-I_PDF-E/raw.md b/marked/G/T-REC-G.999.1-201902-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..73b9e91debfdf69426091b6ffe1b112202bdd86e --- /dev/null +++ b/marked/G/T-REC-G.999.1-201902-I_PDF-E/raw.md @@ -0,0 +1,764 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.999.1** + +(02/2019) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Digital sections and digital line system – Metallic access +networks + +--- + +**Interface between the link layer and the physical +layer for digital subscriber line (DSL) +transceivers** + +Recommendation ITU-T G.999.1 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|--------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| General | G.900–G.909 | +| Parameters for optical fibre cable systems | G.910–G.919 | +| Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s | G.920–G.929 | +| Digital line transmission systems on cable at non-hierarchical bit rates | G.930–G.939 | +| Digital line systems provided by FDM transmission bearers | G.940–G.949 | +| Digital line systems | G.950–G.959 | +| Digital section and digital transmission systems for customer access to ISDN | G.960–G.969 | +| Optical fibre submarine cable systems | G.970–G.979 | +| Optical line systems for local and access networks | G.980–G.989 | +| Metallic access networks | G.990–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.999.1 + +## Interface between the link layer and the physical layer for digital subscriber line (DSL) transceivers + +## Summary + +Recommendation ITU-T G.999.1 defines a point-to-point interface between the LINK layer device such as a network processor and a PHY device supporting multiple DSL lines, such as VDSL2, ADSL2 and SHDSL. + +This revision adds support for 2.5 Gbit/s and 10 Gbit/s LINK/PHY physical interfaces. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|-----------------------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.999.1 | 2009-10-09 | 15 | 11.1002/1000/9677 | +| 1.1 | ITU-T G.999.1 (2009) Cor. 1 | 2010-04-22 | 15 | 11.1002/1000/10703 | +| 1.2 | ITU-T G.999.1 (2009) Amd.1 | 2014-04-04 | 15 | 11.1002/1000/12091 | +| 2.0 | ITU-T G.999.1 | 2019-02-22 | 15 | 11.1002/1000/13755 | + +## Keywords + +Broadband access, copper pairs, LINK/PHY interface, 1 Gbit/s, 2.5 Gbit/s, 10 Gbit/s + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +| | Page | +|-------------------------------------------------------------------------------------|------| +| 1 Scope..... | 1 | +| 2 References..... | 1 | +| 3 Definitions ..... | 1 | +| 4 Abbreviations and acronyms ..... | 1 | +| 5 Reference model ..... | 2 | +| 6 Encapsulation..... | 3 | +| 6.1 Fragmentation..... | 3 | +| 6.2 Identification..... | 5 | +| 6.3 Data flow control..... | 5 | +| 6.4 Ethernet adaptation..... | 7 | +| 6.5 Error detection ..... | 8 | +| 6.6 Resulting encapsulation format and bit-ordering ..... | 8 | +| 7 Configuration parameters ..... | 9 | +| Annex A – Stream identification with multi-line DSL PHY devices ..... | 11 | +| Annex B – LINK/PHY physical interface using 1000BASE-KX (1 Gbit/s Ethernet) ..... | 12 | +| Annex C – LINK/PHY physical interface using 2.5GBASE-KX (2.5 Gbit/s Ethernet) ..... | 15 | +| Annex D – LINK/PHY physical interface using 10GBASE-KR (10 Gbit/s Ethernet) ..... | 18 | +| Bibliography..... | 21 | + + + +## Recommendation ITU-T G.999.1 + +## Interface between the link layer and the physical layer for digital subscriber line (DSL) transceivers + +## 1 Scope + +This Recommendation defines an interface between a LINK device and a PHY device. The interface is a single point-to-point interconnection from the LINK layer device to a PHY device, and it is intended for use with all current and developing xDSL Recommendations (e.g., ADSL2, VDSL2, SHDSL, G.fast, etc.). + +## 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.992.3] Recommendation ITU-T G.992.3 (2009), *Asymmetric digital subscriber line transceivers 2 (ADSL2)*. +- [ITU-T G.992.5] Recommendation ITU-T G.992.5 (2009), *Asymmetric digital subscriber line (ADSL) transceivers – Extended bandwidth ADSL2 (ADSL2plus)*. +- [ITU-T G.9701] Recommendation ITU-T G.9701 (2019), *Fast access to subscriber terminals (G.fast) – Physical layer specification*. +- [IEEE 802.3] IEEE 802.3-2018, *IEEE Standard for Ethernet*. + +- [IEEE 802.3cb] IEEE 802.3cb-2018, *IEEE Standard for Ethernet – Amendment 1: Physical Layer Specifications and Management Parameters for 2.5 Gb/s and 5 Gb/s Operation over Backplane*. + + +## 3 Definitions + +No definitions are provided for this Recommendation. + +## 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|--------------|-------------------------------------| +| DEST MAC ADD | Destination MAC Address | +| DFC | Data Flow Control | +| EoF | End of Frame | +| ETH | Ethernet encapsulation function | +| FCS | Frame Check Sequence | +| GMII | Gigabit Media Independent Interface | +| IFG | Inter-Frame Gap | + +| | | +|----------------|---------------------------------------------------------------| +| MAC | Media Access Control | +| MDI | Media Dependent Interface | +| MII | Media Independent Interface | +| PCP | Priority Code Point | +| PRE | Preamble | +| RXC_MFS | Maximum Fragment data Size supported by near-end receiver | +| SFD | Start Frame Delimiter | +| SID | Stream Identification | +| SoF | Start of Frame | +| SOURCE MAC ADD | Source MAC Address | +| TCI | Tag Control Identifier | +| TPID | Tag Protocol Identifier | +| TX_MFS | Maximum Fragment data Size to be used by near-end transmitter | +| TXC_MFS | Maximum Fragment data Size supported by near-end transmitter | +| VLAN | Virtual Local Area Network | +| XGMII | 10 Gigabit Media Independent Interface | +| XOFF | Transmit Off | +| XON | Transmit On | + +## 5 Reference model + +The LINK/PHY interface reference model is shown in Figure 5-1. This reference model shows the following primitives defined in Annex K of [ITU-T G.992.3] and Annex K of [ITU-T G.992.5]. Primitives are labelled *n*, where *n* corresponds to an individual stream, with *n* = 0..N-1 for a LINK/PHY interface transporting N streams. + +- Stream(*n*).request: This primitive is used by the transmit PHY port to request one or more data units from the transmit LINK layer function to be transported. By the interworking of the request and confirm, the data flow is matched to the PHY port configuration (and underlying functions). +- Stream(*n*).confirm: The transmit LINK layer function passes one or more data units to the PHY port to be transported with this primitive. +- Stream(*n*).indicate: The transmit PHY port passes one or more data units to the receive LINK layer function that have been transported with this primitive. + +The data unit is a block of data consisting of an integer number of octets for transport between a PHY port and a link port. The contents of a data unit is vendor discretionary and outside the scope of this Recommendation. For example, a data unit may contain an Ethernet frame, an Ethernet bonding fragment, one or more ATM cells or an ATM AAL5 PDU. + +The LINK/PHY interface reference model adds the following blocks: + +- frag: Fragmentation of each data unit, with a tag control identification (TCI) field added to each fragment, and with each fragment not to exceed the configured maximum fragment length; +- tag: Identification of fragments through insertion of a data stream or pause identification tag into the TCI field; + +- ETH: Ethernet adaptation by adding fields for compliance with the IEEE 802.3 frame format; the ETH block is configurable to be used or not; +- FCS: Error detection through addition of frame-check-sequence; +- PAUSE: Data flow control through a single PAUSE unit containing the data flow control states of all N streams; +- dec: Decapsulation to recover data units (confirm and indicate primitives) and data flow control states (request primitives), comprising the reverse operation of the frag, tag, and ETH blocks. + +Data unit encapsulation is defined as the cascade of the frag, tag, ETH and FCS blocks. Pause init encapsulation is defined as the cascade of the PAUSE, ETH and FCS blocks. Encapsulation overhead depends on whether or not the ETH block is used. + +![Figure 5-1: Reference model for the LINK/PHY interface. The diagram shows data flow from the LINK PORT (n) on the left to the PHY PORT (n) on the right, separated by the LINK/PHY reference point. On the LINK side, data units (Stream(n).confirm) are processed through Frag(n) and Tag(n) blocks, then multiplexed (Tag mux) for n=0 to N-1. The multiplexed stream passes through Optional ETH and FCS blocks. On the PHY side, the stream is demultiplexed (Tag demux) and processed through dec(n) blocks to produce Stream(n).confirm. A PAUSE unit is shown with PAUSE Rx and PAUSE Tx blocks. The PAUSE Rx block receives Stream(n).request from the dec(n) blocks and sends it to the LINK PORT (n). The PAUSE Tx block receives Stream(n).request from the PHY PORT (n) and sends it to the dec(n) blocks. A note indicates that each pause unit transmits stream(n).request for n = 0...N-1.](562f471e8153729557e6a4ee6343c32c_img.jpg) + +Figure 5-1: Reference model for the LINK/PHY interface. The diagram shows data flow from the LINK PORT (n) on the left to the PHY PORT (n) on the right, separated by the LINK/PHY reference point. On the LINK side, data units (Stream(n).confirm) are processed through Frag(n) and Tag(n) blocks, then multiplexed (Tag mux) for n=0 to N-1. The multiplexed stream passes through Optional ETH and FCS blocks. On the PHY side, the stream is demultiplexed (Tag demux) and processed through dec(n) blocks to produce Stream(n).confirm. A PAUSE unit is shown with PAUSE Rx and PAUSE Tx blocks. The PAUSE Rx block receives Stream(n).request from the dec(n) blocks and sends it to the LINK PORT (n). The PAUSE Tx block receives Stream(n).request from the PHY PORT (n) and sends it to the dec(n) blocks. A note indicates that each pause unit transmits stream(n).request for n = 0...N-1. + +**Figure 5-1 – Reference model for the LINK/PHY interface** + +The LINK device and PHY device shall use a physical point-to-point interconnection. The LINK/PHY interface shall support a data rate of at least 1 Gbit/s for the encapsulated data units. The minimum required bit rate at the LINK/PHY reference point may be higher (e.g., 1.25 Gbit/s if 8B/10B encoding is used). + +## 6 Encapsulation + +### 6.1 Fragmentation + +The fragmentation block (see Figure 5-1) shall fragment each data unit as shown in Figure 6-1. The fragment format is shown in Figure 6-2. + +![Diagram illustrating data unit fragmentation. A large 'Data unit' is shown at the top. Below it, four fragments are shown, each consisting of a 'Header' and 'Fragment data'. Fragment 1 is labeled '(SoF=1 and EoF=0)'. Fragment 2 is labeled '(SoF=0 and EoF=0)'. Fragment n-1 is labeled '(SoF=0 and EoF=0)'. Fragment n is labeled '(SoF=0 and EoF=1)'. The fragments are shown as overlapping blocks, with Fragment 1 starting at the left edge of the data unit, and subsequent fragments starting further right. The last fragment, Fragment n, ends at the right edge of the data unit. A small label 'G.999.1(19)_F6-1' is at the bottom right.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg) + +Diagram illustrating data unit fragmentation. A large 'Data unit' is shown at the top. Below it, four fragments are shown, each consisting of a 'Header' and 'Fragment data'. Fragment 1 is labeled '(SoF=1 and EoF=0)'. Fragment 2 is labeled '(SoF=0 and EoF=0)'. Fragment n-1 is labeled '(SoF=0 and EoF=0)'. Fragment n is labeled '(SoF=0 and EoF=1)'. The fragments are shown as overlapping blocks, with Fragment 1 starting at the left edge of the data unit, and subsequent fragments starting further right. The last fragment, Fragment n, ends at the right edge of the data unit. A small label 'G.999.1(19)\_F6-1' is at the bottom right. + +Figure 6-1 – Data unit fragmentation + +![Diagram showing the non-tagged fragment format. It is a table with columns for field names and bit positions (LSB to MSB). The first row shows the TCI field (2 octets) with bits: 0, 0, 0, 0, 0, 1, EoF, SoF. The second row shows the LENGTH field (2 octets) with bits: 0, 0, 0, 0, 0, 0, 0, 0. The third row shows the Fragment data field (N octets) with bits: 0, 0, 0, 0, 0, 0, 0, 0. A small label 'G.999.1(19)_F6-2' is at the bottom right.](cfda9df1319e04207eb28bcefd1dab7b_img.jpg) + +| | | LSB MSB | | | | | | | | +|----------|---------------|---------|---|---|---|---|---|-----|-----| +| 2 octets | TCI | 0 | 0 | 0 | 0 | 0 | 1 | EoF | SoF | +| | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | +| 2 octets | LENGTH | | | | | | | | | +| | | | | | | | | | | +| N octets | Fragment data | | | | | | | | | +| | | | | | | | | | | +| | | | | | | | | | | +| | | | | | | | | | | + +Diagram showing the non-tagged fragment format. It is a table with columns for field names and bit positions (LSB to MSB). The first row shows the TCI field (2 octets) with bits: 0, 0, 0, 0, 0, 1, EoF, SoF. The second row shows the LENGTH field (2 octets) with bits: 0, 0, 0, 0, 0, 0, 0, 0. The third row shows the Fragment data field (N octets) with bits: 0, 0, 0, 0, 0, 0, 0, 0. A small label 'G.999.1(19)\_F6-2' is at the bottom right. + +Figure 6-2 – Non-tagged fragment format + +The fragment header shall consist of the tag control identifier (TCI) field and the LENGTH field. The capability to insert the LENGTH field is mandatory. When Ethernet encapsulation is enabled, the LENGTH field shall be inserted. When Ethernet encapsulation is disabled, the LENGTH field is configurable to be used or not (see Table 7-1). When the LENGTH MODE is set to 1, the LENGTH field shall be appended; otherwise, the LENGTH field shall not be appended. In the TCI field, the [SoF] and [EoF] bits shall be defined as shown in Table 6-1. The remaining TCI bits shall be as defined in Figure 6-2 and partly further defined by the tag function. The LENGTH field shall contain the number of data unit octets in the fragment data field. + +The LENGTH field, in which the value is encoded as a 16-bit unsigned integer, shall be transmitted with the high order (i.e., most significant) octet first. + +Table 6-1 – Definition of the data unit delimiters + +| [SoF] | [EoF] | Description | +|-------|-------|-----------------------------| +| 0 | 0 | Next fragment of data unit | +| 1 | 0 | First fragment of data unit | +| 0 | 1 | Last fragment of data unit | +| 1 | 1 | Single fragment data unit | + +For each fragment, the value of the length field shall not exceed the maximum fragment data size (TX\_MFS). If the length of a data unit is less than or equal to the TX\_MFS value (see Table 7-1), then that data unit shall be transmitted as a single fragment (i.e., SoF = 1 and EoF = 1). If the length of a data unit is higher than the TX\_MFS value, then that data unit shall be transmitted in multiple fragments, where fragments may have the same or a different length. + +The value of TX\_MFS shall be configurable and shall not exceed the near-end maximum transmit fragment data size (TXC\_MFS), and it shall not exceed the far-end maximum receive fragment data size (RXC\_MFS). If TX\_MFS is configured as ZERO, then each data unit shall be transmitted as a single fragment. The valid values of TX\_MFS, TXC\_MFS, and RXC\_MFS are all integers in the range from 0 to 2047 (included). For interface data rates > 1 Gbit/s, the PHY device shall indicate TXC\_MFS = 2047 and RXC\_MFS = 2047, i.e., all fragment sizes up to 2047 bytes shall be supported by the PHY device. + +NOTE – For interface data rates $\leq 1$ Gbit/s, there are no mandatory values defined for the TXC\_MFS and RXC\_MFS. + +### 6.2 Identification + +The tag block (see Figure 5-1) shall tag each data fragment's TCI field with the stream identification (SID) value, resulting in the tagged fragment format shown in Figure 6-3. + +![Figure 6-3 – Tagged fragment format diagram showing the structure of a fragment with TCI, LENGTH, and Fragment data fields. The TCI field is 2 octets and contains a 10-bit SID (sid0-sid9), EoF, and SoF bits. The LENGTH field is 2 octets. The Fragment data field is N octets.](7e670a2b556b53ea9002dfff3a420e08_img.jpg) + +| | | LSB | | | | MSB | | | | +|----------|---------------|------------------|------------------|------------------|------------------|------------------|------------------|------------------|------------------| +| 2 octets | TCI | sid 0 | sid 1 | 0 | 0 | 0 | 1 | EoF | SoF | +| | | sid 2 | sid 3 | sid 4 | sid 5 | sid 6 | sid 7 | sid 8 | sid 9 | +| 2 octets | LENGTH | | | | | | | | | +| | | | | | | | | | | +| N octets | Fragment data | | | | | | | | | +| | | | | | | | | | | +| | | | | | | | | | | +| | | | | | | | | | | + +G.999.1(19)\_F6-3 + +Figure 6-3 – Tagged fragment format diagram showing the structure of a fragment with TCI, LENGTH, and Fragment data fields. The TCI field is 2 octets and contains a 10-bit SID (sid0-sid9), EoF, and SoF bits. The LENGTH field is 2 octets. The Fragment data field is N octets. + +Figure 6-3 – Tagged fragment format + +The valid SID value is any 10-bit unsigned integer. Up to 1024 data streams can be identified. + +The allocation of a SID value to each data stream is technology dependent, and is defined in Annex A for DSL transceivers. + +### 6.3 Data flow control + +Data flow control (DFC) is a mechanism that prevents congestion by ensuring that transmitting devices do not overwhelm receiving devices with data. This is achieved by the receiving device informing in advance the transmitting device when no further data can be received (e.g., when the RX-Buffer-Filling becomes critical), after which the transmitter stops transmission (= Transmission-Off = XOFF = Active-Backpressure) until the receiver indicates in the same manner that it has regained ability to receive data (e.g., enough free RX-Buffer-Resources) and transmission may continue (= Transmission-On = XON = Inactive-Backpressure). + +For the LINK/PHY interface, data flow control is defined independently for both the transmission of data from the (transmitting) LINK device to the (receiving) PHY device and for the transmission of data from the (transmitting) PHY device to the (receiving) LINK device. Data flow control is defined per data stream to prevent loss of data units. + +To control the data flow from the transmitting device to the receiving device, the receiving device may transmit pause units to the transmitting device. The format of the pause unit is shown in Figure 6-4. + +![Figure 6-4 – Pause unit format diagram showing fields for Opcode, Time, and DFC with bit-level details.](007b053fe94a8348f75128a584503fd0_img.jpg) + +The diagram illustrates the format of a pause unit. It consists of three main fields: OPCODE, TIME, and DFC. The OPCODE field is 2 octets long and is shown with two rows of bits: the first row has all 0s (LSB to MSB) and the second row has a 1 followed by seven 0s. The TIME field is also 2 octets long and is shown with two rows of all 0s. The DFC field is N bits long, where N is a multiple of 8. It is shown with four rows of bits: the first row contains fc0 through fc7, the second and third rows contain ellipses, and the fourth row contains fcN-8 through fcN-1. The columns are labeled LSB at the top left and MSB at the top right. A small label 'G.999.1(19)\_F6-4' is at the bottom right. + +Figure 6-4 – Pause unit format diagram showing fields for Opcode, Time, and DFC with bit-level details. + +Figure 6-4 – Pause unit format + +The OPCODE field shall be set to 0x0001 (i.e., the Ethernet MAC control opcode for pause frame). The OPCODE value allows to uniquely distinguish pause units from tagged data fragments. + +The TIME field shall be set to 0x0000 (i.e., the Ethernet pause frame value for immediate resume of transmission). + +The DFC field shall contain N/8 octets, where N represents the highest used SID, incremented to the next multiple of 8. The N data flow control bits [fc0..fcN-1] represent the data flow control states for the stream with SID = 0 up to the stream with SID = N–1. A data flow control bit shall be set to 0 to indicate the XON-State and shall be set to 1 to indicate XOFF-State for the respective data stream. A data flow control bit corresponding to an unused SID shall be set to 0. + +Upon reception of a pause unit from a receiving device, the transmitting device shall stop transmission within the XOFF-latency as specified in Table 6-2 for the data streams with their flow control bit set to XOFF in this PAUSE unit. + +Upon reception of a pause unit from a receiving device, the transmitting device shall resume transmission for all the data streams with their flow control bit set to XON in this PAUSE unit and was set to XOFF in the last transmitted PAUSE unit and for which the last transmitted fragment was not the last fragment of a data unit. For the case when only one data stream is turned on, transmission of this data stream shall be resumed within the XON-latency as specified in Table 6-2. For the case when multiple data streams are turned on, transmission of data streams should be resumed within XON-latency, if the interface rate allows to transmit at least one fragment for each non-paused data stream within XON-latency. + +Table 6-2 – Specification of XON/XOFF-latencies + +| XOFF-latency | XON-latency | LINK/PHY physical interface | +|-----------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------|-----------------------------| +| 10 µs | 240 µs | Annex B (1000Base-KX) | +| 8 µs | T s – (XOFF-latency) | Annex C (2.5GBASE-KX) | +| 5 µs | T s – (XOFF-latency) | Annex D (10GBASE-KR) | +| NOTE – T s = 20 µs if one of the supported technologies is G.fast according to [ITU-T G. 9701], otherwise T s = 250 µs. | | | + +The XOFF-latency and XON-latency are referred to the LINK/PHY-reference point (see Figure 5-1). The XOFF-latency shall be measured from the last FCS bit of the PAUSE unit transmitted by the PHY device to the last FCS bit of the last fragment transmitted by the LINK-side for the concerned data stream. The XON-latency shall be measured from the last FCS bit of the PAUSE unit transmitted by the PHY device to the last FCS bit of the first fragment transmitted by the LINK-side for the concerned data stream. + +If a data stream is in the XON-state, then the transmitter shall manage the time in-between the transmission of consecutive data fragments belonging to the same data unit, so as to avoid data underflow in the reassembly of the data units at the receiving side. + +Operation with flow control on the PHY-to-LINK data stream (i.e., where the LINK device is the receiving device) is enabled only if the corresponding capability is indicated by both the LINK and PHY devices per the configuration parameter FCTL-us (see Table 7-1). + +### 6.4 Ethernet adaptation + +The ETH block shown in Figure 5-1 adds fields to tagged fragments and Pause Units for compliance with [IEEE 802.3] (data and pause) frame format (after addition of FCS, see clause 6.5). + +The ETH block shall be supported on the PHY-side and shall be configurable to be used or not. On the LINK-side, support of the ETH block is optional; however, if supported, it shall be configurable to be used or not. + +The ETH block shall prepend Source MAC Address field, Destination MAC Address field, VLAN TPID field and MAC TYPE field to tagged fragments and pause units as shown in Figure 6-5. + +The ETH block shall append a padding field to guarantee the frame contains at least 64 octets after addition of FCS. Padding octets shall be set to 0x00. + +![Diagram comparing 'Tagged data fragment' and 'Pause unit' frame structures. The 'Tagged data fragment' includes fields: DEST MAC ADD (6 octets), SOURCE MAC ADD (6 octets), VLAN TPID (2 octets), TCI (2 octets), LENGTH (2 octets), Fragment data, and Padding. The 'Pause unit' includes fields: DEST MAC ADD (6 octets), SOURCE MAC ADD (6 octets), MAC TYPE (2 octets), MAC OPCODE (2 octets), TIME (2 octets), DFC, and Padding. Fields in green (DEST MAC ADD, SOURCE MAC ADD, VLAN TPID, MAC TYPE, MAC OPCODE, TIME) are added by the ETH block. The diagram shows LSB and MSB for each field.](4636adff5682a064f0ae5f13a1d464a6_img.jpg) + +*Fields in green are added by the ETH block.* + +G.999.1(19)\_F6-5 + +Diagram comparing 'Tagged data fragment' and 'Pause unit' frame structures. The 'Tagged data fragment' includes fields: DEST MAC ADD (6 octets), SOURCE MAC ADD (6 octets), VLAN TPID (2 octets), TCI (2 octets), LENGTH (2 octets), Fragment data, and Padding. The 'Pause unit' includes fields: DEST MAC ADD (6 octets), SOURCE MAC ADD (6 octets), MAC TYPE (2 octets), MAC OPCODE (2 octets), TIME (2 octets), DFC, and Padding. Fields in green (DEST MAC ADD, SOURCE MAC ADD, VLAN TPID, MAC TYPE, MAC OPCODE, TIME) are added by the ETH block. The diagram shows LSB and MSB for each field. + +**Figure 6-5 – Ethernet adapted format** + +The destination MAC address shall be set to the MAC address of the far-end device. For pause frames, the destination MAC address may also be set to the globally assigned multicast address 0x0180C2000001. This multicast address has been reserved by [IEEE 802.3] for use in MAC-Control-PAUSE frames. + +The source MAC address shall be set to the near-end device MAC address. + +The VLAN TPID shall be set to 0x8100. This is the VLAN Tag Protocol Identifier, as defined in [IEEE 802.3]. + +The MAC TYPE shall be set to 0x8808. This is the MAC Control Type for pause frames, as defined in [IEEE 802.3]. + +The far-end (i.e., destination) MAC address shall be configurable at the LINK and PHY sides for all frames. For pause frames, it shall be configurable at the LINK side and PHY side whether to use the far-end MAC address or the multicast MAC address. + +### 6.5 Error detection + +The FCS block shown in Figure 5-1 shall append a 4-octet frame check sequence to each (Ethernet adapted) tagged data fragment or pause unit. The FCS shall be calculated over all octets in the (Ethernet adapted) tagged data fragment or pause unit. The FCS shall consist of the 32-bit CRC as defined in [IEEE 802.3] clause 3.2.9 for Ethernet frame FCS. + +The addition of the FCS field is shown in Figure 6-6. + +![Diagram of Figure 6-6: Addition of FCS. It shows a DATA block and an FCS block. The DATA block is part of an '(Ethernet adapted) Tagged data fragment or pause unit'. The FCS block is 4 octets long and contains bits X31, X30, X29, X28, ..., X3, X2, X1, X0. The diagram is labeled with LSB and MSB at the top, and G.999.1(19)_F6-6 at the bottom right.](a26e142d3df5bef41a84a9dd099d7825_img.jpg) + +The diagram illustrates the addition of the Frame Check Sequence (FCS) to a data unit. The top part shows a 'DATA' block within an '(Ethernet adapted) Tagged data fragment or pause unit', with 'LSB' (Least Significant Bit) on the left and 'MSB' (Most Significant Bit) on the right. Below the data block is the 'FCS' block, which is 4 octets long. The FCS contains 32 bits, labeled from $X_{31}$ to $X_0$ . The bits are arranged in a grid: the first row contains $X_{31}, X_{30}, X_{29}, X_{28}$ ; the second row has three empty cells followed by an ellipsis; the third row has three empty cells followed by an ellipsis; the fourth row contains $X_3, X_2, X_1, X_0$ . A bracket on the left indicates the '4 octets' size of the FCS. The label 'G.999.1(19)\_F6-6' is at the bottom right. + +Diagram of Figure 6-6: Addition of FCS. It shows a DATA block and an FCS block. The DATA block is part of an '(Ethernet adapted) Tagged data fragment or pause unit'. The FCS block is 4 octets long and contains bits X31, X30, X29, X28, ..., X3, X2, X1, X0. The diagram is labeled with LSB and MSB at the top, and G.999.1(19)\_F6-6 at the bottom right. + +Figure 6-6 – Addition of FCS + +### 6.6 Resulting encapsulation format and bit-ordering + +When Ethernet encapsulation is not used, i.e., the ETH block is disabled, the final encapsulation format is shown in Figure 6-7. When Ethernet encapsulation is used, i.e., the ETH block is enabled, the final encapsulation format is shown in Figure 6-8. Octets shall be transmitted top-to-bottom. + +![Diagram of Figure 6-7: Final encapsulation format without Ethernet encapsulation. It shows two side-by-side structures: 'Tagged data fragment' and 'Pause unit'. The 'Tagged data fragment' has fields TCI (2 octets), LENGTH (2 octets, green), Fragment data, and FCS (4 octets). The 'Pause unit' has fields MAC OPCODE, TIME, DFC, and FCS (4 octets). Arrows indicate bit transmission (left-to-right) and octet transmission (top-to-bottom). A note states 'Field in green is configurable to be used or not.' and the label 'G.999.1(19)_F6-7' is present.](c036e2540a94b31357ceb0002f0cacab_img.jpg) + +The diagram shows two encapsulation structures side-by-side. The left structure is a 'Tagged data fragment' with fields 'TCI' (2 octets), 'LENGTH' (2 octets, highlighted in green), 'Fragment data', and 'FCS' (4 octets). The right structure is a 'Pause unit' with fields 'MAC OPCODE', 'TIME', 'DFC', and 'FCS' (4 octets). Both structures have 'LSB' and 'MSB' labels at the top. A vertical double-headed arrow between the two structures is labeled 'FCS calculation'. A vertical arrow on the right points downwards, labeled 'Octets transmitted top-to-bottom'. Horizontal arrows at the bottom of each structure point to the right, labeled 'Bits transmitted left-to-right'. A note at the bottom states 'Field in green is configurable to be used or not.' The label 'G.999.1(19)\_F6-7' is at the bottom right. + +Diagram of Figure 6-7: Final encapsulation format without Ethernet encapsulation. It shows two side-by-side structures: 'Tagged data fragment' and 'Pause unit'. The 'Tagged data fragment' has fields TCI (2 octets), LENGTH (2 octets, green), Fragment data, and FCS (4 octets). The 'Pause unit' has fields MAC OPCODE, TIME, DFC, and FCS (4 octets). Arrows indicate bit transmission (left-to-right) and octet transmission (top-to-bottom). A note states 'Field in green is configurable to be used or not.' and the label 'G.999.1(19)\_F6-7' is present. + +Figure 6-7 – Final encapsulation format without Ethernet encapsulation + +![Diagram showing the final encapsulation format with Ethernet encapsulation for a Tagged data fragment and a Pause unit. The Tagged data fragment includes DEST MAC ADD, SOURCE MAC ADD, VLAN TPID, TCI, LENGTH, Fragment data, Padding, and FCS. The Pause unit includes DEST MAC ADD, SOURCE MAC ADD, MAC TYPE, MAC OPCODE, TIME, DFC, Padding, and FCS. Arrows indicate bit transmission direction (left-to-right) and octet transmission direction (top-to-bottom).](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +The diagram illustrates the final encapsulation format for two types of units: a **Tagged data fragment** and a **Pause unit**. Both units share a common header structure at the top, followed by data, padding, and a Frame Check Sequence (FCS). + +**Tagged data fragment structure:** + +- Header:** + - DEST MAC ADD (6 octets) + - SOURCE MAC ADD (6 octets) + - VLAN TPID (2 octets) + - TCI (2 octets) + - LENGTH (2 octets) +- Fragment data:** Variable length data. +- Padding:** Variable length padding. +- FCS:** 4 octets. + +**Pause unit structure:** + +- Header:** + - DEST MAC ADD (6 octets) + - SOURCE MAC ADD (6 octets) + - MAC TYPE (2 octets) + - MAC OPCODE (2 octets) + - TIME (2 octets) +- DFC:** Variable length data. +- Padding:** Variable length padding. +- FCS:** 4 octets. + +**Transmission Indicators:** + +- Bits transmitted left-to-right:** Indicated by a horizontal arrow at the bottom of each unit. +- Octets transmitted top-to-bottom:** Indicated by a vertical arrow on the right side of the Pause unit. +- FCS calculation:** Indicated by a vertical double-headed arrow between the LENGTH/DFC field and the FCS field in both units. + +G.999.1(19)\_F6-8 + +Diagram showing the final encapsulation format with Ethernet encapsulation for a Tagged data fragment and a Pause unit. The Tagged data fragment includes DEST MAC ADD, SOURCE MAC ADD, VLAN TPID, TCI, LENGTH, Fragment data, Padding, and FCS. The Pause unit includes DEST MAC ADD, SOURCE MAC ADD, MAC TYPE, MAC OPCODE, TIME, DFC, Padding, and FCS. Arrows indicate bit transmission direction (left-to-right) and octet transmission direction (top-to-bottom). + +Figure 6-8 – Final encapsulation format with Ethernet encapsulation + +## 7 Configuration parameters + +Table 7-1 summarizes the encapsulation configuration parameters defined in clause 6 and defines a detailed format. + +Table 7-1 – Configuration parameters for the encapsulation + +| NAME | SIZE | LINK | PHY | Definition | +|-----------------------------------------------------------------|--------|------|-----|----------------------------------------------------------------------------------------------------------------------------| +| FRAGMENTATION (clause 6.1) | | | | | +| TXC_MFS | [10:0] | R | R | Maximum fragment data size supported by near-end transmitter. | +| RXC_MFS | [10:0] | R | R | Maximum fragment data size supported by near-end receiver. | +| TX_MFS | [10:0] | R/W | R/W | Maximum fragment data size to be used by near-end transmitter. | +| LENGTH MODE | [0] | R/W | R/W | 0: LENGTH field shall not be appended.
1: LENGTH field shall be appended. | +| FLOW CONTROL on the PHY-to-LINK data stream (clause 6.3) | | | | | +| FCTL-us | [0] | R/W | R/W | 0: Flow Control on the PHY-to-LINK data stream Not Supported.
1: Flow Control on the PHY-to-LINK data stream Supported. | +| ETHERNET ADAPTATION (clause 6.4) | | | | | +| ETH | [0] | R/W | R/W | 0: Ethernet Adaptation shall not be used.
1: Ethernet Adaptation shall be used. | +| NE_MAC_ADDRESS | [47:0] | R/W | R/W | Near-end MAC Address | +| FE_MAC_ADDRESS | [47:0] | R/W | R/W | Far-end MAC Address | + +**Table 7-1 – Configuration parameters for the encapsulation** + +| NAME | SIZE | LINK | PHY | Definition | +|-----------------|-------------|-------------|------------|----------------------------------------------------------------------------------------------------------------------------------------------------------| +| PAUSE_MULTICAST | [0] | R/W | R/W | 0: Pause frame shall have far-end MAC address as destination MAC address.
1: Pause frame shall have multicast MAC address as destination MAC address. | + +If the ETH bit is set to ONE, then the LENGTH MODE bit shall also be set to ONE. + +## Annex A + +### Stream identification with multi-line DSL PHY devices + +(This annex forms an integral part of this Recommendation.) + +DSL transceivers are based on transparent transport of data streams. A TPS-TC data stream is an input to a TPS-TC, where a data unit equals a 53-octet ATM cell (ATM-TC) (see clause K.2 of [ITU-T G.992.3] or clause K.2 of [b-ITU-T G.993.2]) or a packet (PTM-TC) (see clause K.3 of [ITU-T G.992.3] or clause K.3 of [b-ITU-T G.993.2] or clause 8.3 of [ITU-T G.9701]). In the Link/PHY interface, a data unit may, for example, contain an Ethernet frame, an Ethernet bonding fragment, one or more ATM cells or an ATM AAL5 PDU (see clause 5). A TPS-TC connects to a bearer channel. In the case of PTM-TC with pre-emption, a bearer channel may carry a high priority data stream and low priority data stream. Hence, for DSL transceivers, the stream identification (SID) shall identify a particular DSL line, a particular bearer channel and a particular priority within the bearer in the DSL line. + +NOTE – The three primitives defined in clause 5 correspond to the TPS-TC primitives defined in the ADSL2 [ITU-T G.992.3] and VDSL2 [b-ITU-T G.993.2] Recommendations. + +This annex defines a mapping of the stream identifier (SID) for a multi-line DSL PHY device, with up to 256 DSL lines/transceivers, up to 2 bearer channels and possible use of pre-emption. + +The line/transceiver number (line[7:0], values 0 to 255), the bearer channel (BC, values 0 or 1), and the priority (PR, values 0 = low or 1 = high) shall be mapped into the stream identification (SID[9:0], values 0 to 1024) as shown in Figure A.1. + +| | | | | | | | | | | +|-------------------|-------------------|-------------------|-------------------|-------------------|-------------------|-------------------|-------------------|------------------|------------------| +| sid 9 | sid 8 | sid 7 | sid 6 | sid 5 | sid 4 | sid 3 | sid 2 | sid 1 | sid 0 | +| line 7 | line 6 | line 5 | line 4 | line 3 | line 2 | line 1 | line 0 | BC | PR | + +G.999.1(19)\_FA.1 + +Figure A.1 – Mapping of line, bearer and priority into the SID + +In general, for a PHY device supporting N transceivers, there are N\*4 SID values and $\left\lceil \frac{N}{2} \right\rceil = \left\lceil \frac{N \cdot 4}{8} \right\rceil$ octets in the DFC field of the pause unit. For example: + +- If the PHY device has 256 DSL transceivers, then the DFC field in the pause unit (see Figure 6-4) contains 128 octets. +- If the PHY device has 84 DSL transceivers, then the DFC field in the pause unit (see Figure 6-4) contains 42 octets. This is the maximum number of transceivers that keeps the encapsulated pause unit (including Ethernet adaptation) at the [IEEE 802.3] pause frame length of 64 octets. +- If the PHY device has only 12 DSL transceivers, then the DFC field in the pause unit (see Figure 6-4) contains only 6 octets. If Ethernet adaptation is used, the Ethernet frame contains 36 padding octets. + +## Annex B + +### LINK/PHY physical interface using 1000BASE-KX (1 Gbit/s Ethernet) + +(This annex forms an integral part of this Recommendation.) + +This annex defines the LINK/PHY physical interface, based on [IEEE 802.3] 1000BASE-KX Ethernet (also known as Backplane Ethernet). Compliance to this annex requires support of a relevant subset of [IEEE 802.3] 1000BASE-KX Ethernet (clause 70) below the GMII, which include the PCS, PMA, and PMD layers (see Table B.1 for relevant sections of 1000Base-KX). The sections of [IEEE 802.3] 1000Base-KX Ethernet (clause 70) that are not identified in Table B.1 are vendor discretionary. + +Note that the GMII is an optional interface. However, if the GMII is not implemented, a conforming implementation must behave functionally as though the GMII is present. + +Figure B.1 shows the LINK/PHY interface based on 1000BASE-KX. The encapsulation block is defined in the main body of this Recommendation. + +![Diagram of the LINK/PHY interface based on 1000BASE-KX. The diagram shows two identical protocol stacks connected by a physical interface. Each stack consists of 'Higher layers' (Data unit), 'Encapsulation/decapsulation' (OSI DATA-LINK layer), and 'Physical media independent layer'. Below this is the 'OSI PHY layer', which includes 'GMII' (1Gbit/s), '8B/10B PCS', 'PMA', 'PMD', and 'AN (Optional)'. The 'Physical media dependent layers' connect to an 'MDI'. The 'Physical interface' between the MDIs is labeled '1000BASE-KX' and '1.25Gbit/s'. A label 'Interface-media, signal-encoding and transmission rate' is also present. The entire interface is labeled 'Transmission rate'.](8592a32c2fdf17c1e562f0ba6b7e8e1a_img.jpg) + +G.999.1(09)\_FB.1 + +Diagram of the LINK/PHY interface based on 1000BASE-KX. The diagram shows two identical protocol stacks connected by a physical interface. Each stack consists of 'Higher layers' (Data unit), 'Encapsulation/decapsulation' (OSI DATA-LINK layer), and 'Physical media independent layer'. Below this is the 'OSI PHY layer', which includes 'GMII' (1Gbit/s), '8B/10B PCS', 'PMA', 'PMD', and 'AN (Optional)'. The 'Physical media dependent layers' connect to an 'MDI'. The 'Physical interface' between the MDIs is labeled '1000BASE-KX' and '1.25Gbit/s'. A label 'Interface-media, signal-encoding and transmission rate' is also present. The entire interface is labeled 'Transmission rate'. + +**Figure B.1 – LINK/PHY interface based on 1000BASE-KX** + +The OSI's PHY-Layer part of the LINK/PHY interface (see Figure B.1): + +- Shall be compliant with a relevant subset of [IEEE 802.3] 1000BASE-KX standard clause 70 per Table B.1. Note that Table B.1 lists the relevant section headings of [IEEE 802.3] clause 70 for which compliance is required: 'Req' means that full support of mandatory items in the section is required, and 'Partial' means partially supported with identification in the comment column of the appropriate elements required. Compliance to the other sections of [IEEE 802.3] clause 70 is optional. +- Shall operate in Full-Duplex mode and at 1 Gbit/s data rate at the GMII or equivalent interface (which is 1.25 Gbit/s at the MDI interface). The Auto-Negotiation capability is not necessary and therefore not required. +- The interface between the physical media independent layer and the physical media dependent layers (MII) is vendor discretionary. + +- Shall use PREamble (PRE), start frame delimiter (SFD) and inter-frame-gaps (IFG) for detecting byte and (Ethernet adapted) fragment boundaries; the following Ethernet CSMA/CD MAC parameters (clauses 3 and 4 of [IEEE 802.3]) shall be applied: + - PRE: 7 octets (clause 3.2.1) + - SFD: 1 octet (clause 3.2.2) + - IFG: 12 octets (clause 4.4.2) +- Optionally, the minimum number of IFG octets may be reduced to 3. If Ethernet adaptation is not used, then PREamble octets may optionally be reduced to 2. +- In general, all options can be used when both the LINK and the PHY devices are configured to support it; the means for enabling each option in the LINK and PHY devices are vendor discretionary. + +**Table B.1 – Subset of 1000Base-KX for Annex B compliance** + +| Section # | Section Title | Support | Comment | +|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|-------------------| +| 70.1 | Overview | Partial | w/o clause 45 | +| 70.2 | Physical media dependent (PMD) service interface | Req. | w/o Signal Detect | +| 70.4 | Delay constraints | Req. | | +| 70.6 | PMD functional specifications | Partial | w/o Signal Detect | +| 70.6.1 | Link block diagram | Partial | w/o Signal Detect | +| 70.6.2 | PMD transmit function | Req. | | +| 70.6.3 | PMD receive function | Req. | | +| 70.6.6 | Loopback mode | Req. | w/o clause 45 | +| 70.7.1 | Transmitter characteristics | Req. | | +| 70.7.1.1 | Test fixtures | Req. | | +| 70.7.1.2 | Test fixture impedance | Req. | | +| 70.7.1.3 | Signalling speed | Req. | | +| 70.7.1.4 | Differential output eye mask | Req. | | +| 70.7.1.5 | Output amplitude | Req. | – | +| 70.7.1.6 | Differential output return loss | Req. | | +| 70.7.1.7 | Transition time | Req. | | +| 70.7.1.8 | Transmit jitter | Req. | | +| 70.7.1.9 | Transmit jitter test requirements | Req. | | +| 70.7.2 | Receiver characteristics | Req. | | +| 70.7.2.1 | Receiver interference tolerance | Req. | | +| 70.7.2.2 | Signalling speed range | Req. | | +| 70.7.2.3 | AC-coupling | Req. | | +| 70.7.2.4 | Input signal amplitude | Req. | | +| 70.7.2.5 | Differential input return loss | Req. | | +| 70.9 | Environmental specifications | Req. | – | +| 70.10 | Protocol implementation conformance statement (PICS) proforma for clause 70, physical media dependent (PMD) sublayer and baseband medium, type 1000BASE-KX | | | +| 70.10.1 | Introduction | Req. | – | + +**Table B.1 – Subset of 1000Base-KX for Annex B compliance** + +| Section # | Section Title | Support | Comment | +|------------------|-----------------------------------------|----------------|---------------------------------------| +| 70.10.3 | Major capabilities/options | Partial | only PCS, FD, and DC | +| 70.10.4.2 | PMD functional specifications | Partial | only FS1, FS2, FS3, FS4, FS8, and FS9 | +| 70.10.4.4 | Transmitter electrical characteristics | Req. | – | +| 70.10.4.5 | Receiver electrical characteristics | Req. | – | +| 70.10.4.6 | Environmental and safety specifications | Req. | – | + +## Annex C + +### LINK/PHY physical interface using 2.5GBASE-KX (2.5 Gbit/s Ethernet) + +(This annex forms an integral part of this Recommendation.) + +This annex defines the LINK/PHY physical interface, based on [IEEE 802.3cb] 2.5GBASE-KX Ethernet (also known as 2.5 Gbit/s Backplane Ethernet). Compliance to this annex requires support of a relevant subset of [IEEE 802.3cb] 2.5GBASE-KX Ethernet (clause 128) below the XGMII, which include the PCS, PMA, and PMD layers (see Table C.1 for relevant sections of 2.5GBASE-KX). The sections of [IEEE 802.3cb] 2.5GBASE-KX Ethernet (clause 128) that are not identified in Table C.1 are vendor discretionary. + +Note that the XGMII is an optional interface. However, if the XGMII is not implemented, a conforming implementation must behave functionally as though the XGMII is present. + +Figure C.1 shows the LINK/PHY interface based on 2.5GBASE-KX. The encapsulation block is defined in the main body of this Recommendation. + +![Diagram of the LINK/PHY interface based on 2.5GBASE-KX. The diagram shows two communicating entities, each with a stack of layers. The top stack includes 'Higher layers', 'Data unit', 'Encapsulation/decapsulation', and 'Physical medium independent layer'. Below this is the 'XGMII 2.5 Gbit/s' interface. The bottom stack includes '8B/10B PCS', 'PMA', 'PMD', and 'AN (Optional)', which are part of the 'Physical medium dependent layers'. These layers connect to an 'MDI' (Medium Dependent Interface). The MDIs are connected by a 'Physical interface' labeled '2.5 GBASE-KX' and '3.125 Gbit/s'. The entire physical interface section is labeled 'Interface-media, signal-encoding and transmission rate' and 'Transmission rate'. Vertical double-headed arrows indicate the 'OSI DATA-LINK layer' and 'OSI PHY layer' boundaries between the two entities.](4cc7cdce3d498d8b0ba033a9be24ade5_img.jpg) + +Diagram of the LINK/PHY interface based on 2.5GBASE-KX. The diagram shows two communicating entities, each with a stack of layers. The top stack includes 'Higher layers', 'Data unit', 'Encapsulation/decapsulation', and 'Physical medium independent layer'. Below this is the 'XGMII 2.5 Gbit/s' interface. The bottom stack includes '8B/10B PCS', 'PMA', 'PMD', and 'AN (Optional)', which are part of the 'Physical medium dependent layers'. These layers connect to an 'MDI' (Medium Dependent Interface). The MDIs are connected by a 'Physical interface' labeled '2.5 GBASE-KX' and '3.125 Gbit/s'. The entire physical interface section is labeled 'Interface-media, signal-encoding and transmission rate' and 'Transmission rate'. Vertical double-headed arrows indicate the 'OSI DATA-LINK layer' and 'OSI PHY layer' boundaries between the two entities. + +G.999.1(19)\_FC-1 + +**Figure C.1 – LINK/PHY interface based on 2.5GBASE-KX** + +The OSI's PHY-Layer part of the LINK/PHY interface (see Figure C.1): + +- Shall be compliant with a relevant subset of [IEEE 802.3cb] 2.5GBASE-KX standard clause 128 according to Table C.1. Note that Table C.1 lists the relevant section headings of clause 128 of [IEEE 802.3cb] for which compliance is required. 'Req' means that full support of mandatory items in the section is required, and 'Partial' means partially supported with identification in the comment column of the appropriate elements required. Compliance to the other sections of clause 128 of [IEEE 802.3cb] is optional. +- Shall operate in full-duplex mode and at 2.5 Gbit/s data rate at the XGMII or equivalent interface (which is 3.125 Gbit/s at the MDI interface). The auto-negotiation capability is not necessary and therefore not required. +- The interface between the physical media independent layer and the physical media dependent layers (MII) is vendor discretionary. + +- Shall use Preamble (PRE), start frame delimiter (SFD) and inter-frame-gaps (IFG) for detecting byte and (Ethernet adapted) fragment boundaries. The following Ethernet CSMA/CD MAC parameters (clauses 3 and 4 of [IEEE 802.3]) shall be applied: + - PRE: 7 octets (clause 3.2.1) + - SFD: 1 octet (clause 3.2.2) + - IFG: 12 octets (clause 4.4.2) +- Optionally, the minimum number of IFG octets may be reduced to 3. If Ethernet adaptation is not used, then Preamble octets may optionally be reduced to 2. +- In general, all options can be used when both the LINK and the PHY devices are configured to support it. The means for enabling each option in the LINK and PHY devices are vendor discretionary. + +**Table C.1 – Subset of 2.5GBASE-KX for Annex C compliance** + +| Section # | Section Title | Support | Comment | +|-----------|--------------------------------------------------------------------------------------------------------|---------|-------------------| +| 128.1 | Overview | Partial | w/o clause 45 | +| 128.2 | Physical media dependent (PMD) service interface | Req. | w/o Signal Detect | +| 128.4 | Delay constraints | Req. | | +| 128.6 | PMD functional specifications | Partial | w/o Signal Detect | +| 128.6.1 | Link block diagram | Partial | w/o Signal Detect | +| 128.6.2 | PMD transmit function | Req. | | +| 128.6.3 | PMD receive function | Req. | | +| 128.6.6 | Loopback mode | Req. | w/o clause 45 | +| 128.7.1 | Transmitter characteristics | Req. | | +| 128.7.1.1 | Test fixtures | Req. | | +| 128.7.1.2 | Test fixture characteristics | Req. | | +| 128.7.1.3 | Signalling speed | Req. | | +| 128.7.1.4 | Output amplitude | Req. | – | +| 128.7.1.5 | Differential output return loss | Req. | | +| 128.7.1.6 | Common-mode output return loss | Req. | | +| 128.7.1.7 | Transition time | Req. | | +| 128.7.1.8 | Transmit jitter test requirements | Req. | | +| 128.7.1.9 | Transmit jitter | Req. | | +| 128.7.2 | Receiver characteristics | Req. | | +| 128.7.2.1 | Receiver interference tolerance | Req. | | +| 128.7.2.2 | Signalling speed range | Req. | | +| 128.7.2.3 | AC-coupling | Req. | | +| 128.7.2.4 | Input signal amplitude | Req. | | +| 128.7.2.5 | Differential input return loss | Req. | | +| 128.9 | Environmental specifications | Req. | – | +| 128.10 | Protocol implementation conformance statement (PICS) proforma for clause 128, physical media dependent | | | + +**Table C.1 – Subset of 2.5GBASE-KX for Annex C compliance** + +| Section # | Section Title | Support | Comment | +|------------------|------------------------------------------------------|----------------|-----------------------------------| +| | (PMD) sublayer and baseband medium, type 2.5GBASE-KX | | | +| 128.10.1 | Introduction | Req. | – | +| 128.10.3 | Major capabilities/options | Partial | only PCS and DC | +| 128.10.4.2 | PMD functional specifications | Partial | only FS3, FS4, FS5, FS6, and FS11 | +| 128.10.4.3 | Transmitter electrical characteristics | Req. | – | +| 128.10.4.4 | Receiver electrical characteristics | Req. | – | +| 128.10.4.5 | Environmental and safety specifications | Req. | – | + +## Annex D + +### LINK/PHY physical interface using 10GBASE-KR (10 Gbit/s Ethernet) + +(This annex forms an integral part of this Recommendation.) + +This annex defines the LINK/PHY physical interface, based on [IEEE 802.3] 10GBASE-KR Ethernet (also known as serial 10 Gbit/s Backplane Ethernet). Compliance to this annex requires support of a relevant subset of [IEEE 802.3] 10GBASE-KR Ethernet (clause 72) below the XGMII, which include the PCS, PMA, and PMD layers (see Table D.1 for relevant sections of 10GBASE-KR). The sections of [IEEE 802.3] 10GBASE-KR Ethernet (clause 72) that are not identified in Table D.1 are vendor discretionary. + +Note that the XGMII is an optional interface. However, if the XGMII is not implemented, a conforming implementation must behave functionally as though the XGMII is present. + +Figure D.1 shows the LINK/PHY interface based on 10GBASE-KR. The encapsulation block is defined in the main body of this Recommendation. + +![Diagram of the LINK/PHY interface based on 10GBASE-KR showing the OSI layers and data flow.](171115f072e42b379238ed0dd438e9d7_img.jpg) + +The diagram illustrates the LINK/PHY interface based on 10GBASE-KR, showing the flow of data through various layers and interfaces. On the left, 'Higher layers' provide a 'Data unit' to an 'Encapsulation/decapsulation' block, which sits above the 'Physical medium independent layer'. This layer connects to the 'XGMII 10 Gbit/s' interface. Below the XGMII, the 'Physical medium dependent layers' are shown, containing '64B/66B PCS', 'PMA', 'PMD', and an 'AN (Optional)' component. This is followed by an 'MDI' block. The bottom section represents the 'Physical interface' for '10 GBASE-KR' at a rate of '10.3125 Gbit/s', labeled as 'Interface-media, signal-encoding and transmission rate'. A central vertical double-headed arrow indicates the 'OSI DATA-LINK layer' between the encapsulation blocks and the 'OSI PHY layer' between the physical medium dependent layers. The right side of the diagram mirrors the left side, showing the same layers and interfaces for the receiving end. A long double-headed arrow at the bottom, spanning both sides, is labeled 'Transmission rate'. + +Diagram of the LINK/PHY interface based on 10GBASE-KR showing the OSI layers and data flow. + +G.999.1(19)\_FD-1 + +**Figure D.1 – LINK/PHY interface based on 10GBASE-KR** + +The OSI's PHY-Layer part of the LINK/PHY interface (see Figure D.1): + +- Shall be compliant with a relevant subset of [IEEE 802.3] 10GBASE-KR standard clause 72 according to Table D.1. Note that Table D.1 lists the relevant section headings of [IEEE 802.3] clause 72 for which compliance is required. 'Req' means that full support of mandatory items in the section is required, and 'Partial' means partially supported with identification in the comment column of the appropriate elements required. Compliance to the other sections of [IEEE 802.3] clause 72 is optional. +- Shall operate in full-duplex mode and at 10 Gbit/s data rate at the XGMII or equivalent interface (which is 10.3125 Gbit/s at the MDI interface). The auto-negotiation capability is not necessary and therefore not required. +- The interface between the physical media independent layer and the physical media dependent layers (MII) is vendor discretionary. + +- Shall use PREamble (PRE), start frame delimiter (SFD) and inter-frame-gaps (IFG) for detecting byte and (Ethernet adapted) fragment boundaries. The following Ethernet CSMA/CD MAC parameters (clauses 3 and 4 of [IEEE 802.3]) shall be applied: + - PRE: 7 octets (clause 3.2.1) + - SFD: 1 octet (clause 3.2.2) + - IFG: 12 octets (clause 4.4.2) +- Optionally, the minimum number of IFG octets may be reduced to 8. If Ethernet adaptation is not used, then PREamble octets may optionally be reduced to 3. +- In general, all options can be used when both the LINK and the PHY devices are configured to support it; the means for enabling each option in the LINK and PHY devices are vendor discretionary. + +**Table D.1 – Subset of 10GBASE-KR for Annex D compliance** + +| Section # | Section title | Support | Comment | +|-----------|--------------------------------------------------|---------|---------------| +| 72.1 | Overview | Partial | w/o clause 45 | +| 72.2 | Physical media dependent (PMD) service interface | Req. | | +| 72.4 | Delay constraints | Req. | | +| 72.6 | PMD functional specifications | Req. | | +| 72.6.1 | Link block diagram | Req. | | +| 72.6.2 | PMD transmit function | Req. | | +| 72.6.3 | PMD receive function | Req. | | +| 72.6.6 | Loopback mode | Partial | w/o clause 45 | +| 72.6.10 | PMD control function | Req. | | +| 72.7.1 | Transmitter characteristics | Req. | | +| 72.7.1.1 | Test fixtures | Req. | | +| 72.7.1.2 | Test fixture impedance | Req. | | +| 72.7.1.3 | Signalling speed | Req. | | +| 72.7.1.4 | Output amplitude | Req. | | +| 72.7.1.5 | Differential output return loss | Req. | – | +| 72.7.1.6 | Common-mode return loss | Req. | | +| 72.7.1.7 | Transition time | Partial | w/o clause 45 | +| 72.7.1.8 | Transmit jitter test requirements | Partial | w/o clause 45 | +| 72.7.1.9 | Transmit jitter | Req. | | +| 72.7.1.10 | Transmitter output waveform | Req. | | +| 72.7.1.11 | Transmitter output waveform requirements | Req. | | +| 72.7.2 | Receiver characteristics | Req. | | +| 72.7.2.1 | Receiver interference tolerance | Req. | | +| 72.7.2.2 | Signalling speed range | Req. | | +| 72.7.2.3 | AC-coupling | Req. | | +| 72.7.2.4 | Input signal amplitude | Req. | | +| 72.7.2.5 | Differential input return loss | Req. | | +| 72.9 | Environmental specifications | Req. | – | + +**Table D.1 – Subset of 10GBASE-KR for Annex D compliance** + +| Section # | Section title | Support | Comment | +|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|-------------------------------------------------| +| 72.10 | Protocol implementation conformance statement (PICS) proforma for clause 70, physical media dependent (PMD) sublayer and baseband medium, type 1000BASE-KX | | | +| 72.10.1 | Introduction | Req. | – | +| 72.10.3 | Major capabilities/options | Partial | only PCS, PMA, and DC | +| 72.10.4.2 | PMD functional specifications | Partial | only FS1, FS2, FS3, FS4, FS7, FS8, FS9 and FS12 | +| 72.10.4.4 | PMD Control functions | Req. | | +| 72.10.4.5 | Transmitter electrical characteristics | Req. | – | +| 72.10.4.6 | Receiver electrical characteristics | Req. | – | +| 72.10.4.7 | Environmental and safety specifications | Req. | – | + +## Bibliography + +- [b-ITU-T G.993.2] Recommendation ITU-T G.993.2 (2006), *Very high speed digital subscriber line transceivers 2 (VDSL2)*. +- [b-IEEE 802.1D] IEEE 802.1D-2004, *IEEE Standard for Local and metropolitan area networks Media Access Control (MAC) Bridges*, Revision of 802.1D-1998. + +- [b-IEEE 802.1Q] IEEE 802.1Q-2005, *IEEE standard for local and metropolitan area networks virtual bridged local area networks*. + + + + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file diff --git a/marked/G/T-REC-G.9991-201903-I_PDF-E/raw.md b/marked/G/T-REC-G.9991-201903-I_PDF-E/raw.md new file mode 100644 index 0000000000000000000000000000000000000000..b8e7ae7979fdd83f698c0f3886e68ab7db008519 --- /dev/null +++ b/marked/G/T-REC-G.9991-201903-I_PDF-E/raw.md @@ -0,0 +1,3077 @@ + + +**ITU-T** + +TELECOMMUNICATION +STANDARDIZATION SECTOR +OF ITU + +**G.9991** + +(03/2019) + +SERIES G: TRANSMISSION SYSTEMS AND MEDIA, +DIGITAL SYSTEMS AND NETWORKS + +Access networks – In premises networks + +--- + +**High-speed indoor visible light communication +transceiver – System architecture, physical +layer and data link layer specification** + +Recommendation ITU-T G.9991 + +# ITU-T G-SERIES RECOMMENDATIONS **TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS** + +| | | +|----------------------------------------------------------------------------------------------------------------------------------------------|----------------------| +| INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS | G.100–G.199 | +| GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS | G.200–G.299 | +| INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES | G.300–G.399 | +| GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES | G.400–G.449 | +| COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY | G.450–G.499 | +| TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS | G.600–G.699 | +| DIGITAL TERMINAL EQUIPMENTS | G.700–G.799 | +| DIGITAL NETWORKS | G.800–G.899 | +| DIGITAL SECTIONS AND DIGITAL LINE SYSTEM | G.900–G.999 | +| MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE – GENERIC AND USER-RELATED ASPECTS | G.1000–G.1999 | +| TRANSMISSION MEDIA CHARACTERISTICS | G.6000–G.6999 | +| DATA OVER TRANSPORT – GENERIC ASPECTS | G.7000–G.7999 | +| PACKET OVER TRANSPORT ASPECTS | G.8000–G.8999 | +| ACCESS NETWORKS | G.9000–G.9999 | +| Metallic access networks | G.9700–G.9799 | +| Optical line systems for local and access networks | G.9800–G.9899 | +| In premises networks | G.9900–G.9999 | + +*For further details, please refer to the list of ITU-T Recommendations.* + +## Recommendation ITU-T G.9991 + +## High-speed indoor visible light communication transceiver – System architecture, physical layer and data link layer specification + +## Summary + +Recommendation ITU-T G.9991 specifies the system architecture, physical (PHY) layer and data link layer (DLL) for high-speed indoor optical wireless communication transceiver using visible light. + +## History + +| Edition | Recommendation | Approval | Study Group | Unique ID* | +|---------|----------------|------------|-------------|---------------------------------------------------------------------------| +| 1.0 | ITU-T G.9991 | 2019-03-22 | 15 | 11.1002/1000/13781 | + +## Keywords + +Home network, light emitting diode, optical wireless communication, visible light communication. + +--- + +\* To access the Recommendation, type the URL in the address field of your web browser, followed by the Recommendation's unique ID. For example, . + +## FOREWORD + +The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. + +The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. + +The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. + +In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. + +## NOTE + +In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. + +Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. + +## INTELLECTUAL PROPERTY RIGHTS + +ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. + +As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at . + +© ITU 2019 + +All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. + +## Table of Contents + +###### Page + +| | | | +|-------|-----------------------------------------------------------------------|----| +| 1 | Scope..... | 1 | +| 2 | References..... | 1 | +| 3 | Definitions ..... | 1 | +| 3.1 | Terms defined elsewhere ..... | 1 | +| 3.2 | Terms defined in this Recommendation..... | 2 | +| 4 | Abbreviations and acronyms ..... | 4 | +| 5 | Conventions ..... | 6 | +| 5.1 | Bit ordering convention ..... | 6 | +| 6 | System architecture and reference models ..... | 6 | +| 6.1 | System architecture ..... | 6 | +| 6.2 | Reference models ..... | 13 | +| 6.3 | Management-plane model of a VLC system ..... | 15 | +| 7 | Topology profiles..... | 15 | +| 7.1 | Topology profiles based on the operational modes ..... | 16 | +| 8 | Physical layer specification I (PHY layer based on ITU-T G.9960)..... | 16 | +| 8.1 | Medium independent specification..... | 16 | +| 8.2 | Medium dependent specification..... | 32 | +| 9 | Physical layer specification II (ACO-OFDM)..... | 35 | +| 9.1 | Medium independent specification..... | 35 | +| 9.2 | Medium dependent specification..... | 41 | +| 10 | Data link layer specification ..... | 41 | +| 10.1 | Functional model and frame formats ..... | 41 | +| 10.2 | Medium access ..... | 46 | +| 10.3 | Control parameters for APC, LLC and MAC ..... | 57 | +| 10.4 | Functions of the end-point node ..... | 59 | +| 10.5 | Domain master node functional capabilities ..... | 60 | +| 10.6 | Addressing scheme ..... | 60 | +| 10.7 | Medium access plan (MAP) frame ..... | 61 | +| 10.8 | Retransmission and acknowledgement protocol ..... | 67 | +| 10.9 | Management and control message format ..... | 67 | +| 10.10 | Channel estimation protocol..... | 67 | +| 10.11 | Connection management ..... | 67 | +| 10.12 | Operation in the presence of neighbouring domains ..... | 67 | +| 10.13 | Inter-domain mobility support..... | 67 | +| 10.14 | Dimming support and flicker avoidance ..... | 70 | +| 10.15 | Inter-bandplan interoperability ..... | 70 | + +| | Page | | +|--------------|------------------------------------------------------------------------------------------------|----| +| 10.16 | MIMO transmission..... | 70 | +| 10.17 | Operation with non-VLC uplink ..... | 70 | +| 10.18 | DLL multicast stream ..... | 70 | +| 10.19 | Node information and capabilities exchange ..... | 70 | +| 10.20 | Metrics acquisition protocol ..... | 70 | +| 10.21 | Operation in power saving modes ..... | 70 | +| 10.22 | Layer 2 configuration and management protocol..... | 70 | +| 10.23 | Payload compression in management messages ..... | 70 | +| 10.24 | PHY multicast binding protocol ..... | 71 | +| 11 | Security ..... | 71 | +| 12 | Management of ITU-T G.9991 nodes ..... | 71 | +| 12.1 | Architecture and reference model ..... | 71 | +| 12.2 | ITU-T G.9991 interface data model ..... | 73 | +| Annex A | – LCMP communication through L1 interface ..... | 74 | +| A.1 | LCMP_CONTROL in L1 interface ..... | 74 | +| A.2 | Data model for L1 interface ..... | 74 | +| Annex B | – LCMP communication through L6 interface..... | 75 | +| B.1 | LCMP_CONTROL in L6 interface ..... | 75 | +| B.2 | Data model for L6 interface ..... | 75 | +| Annex C | – ITU-T G.9991 Capabilities ..... | 77 | +| C.1 | ITU-T G.9991 capabilities..... | 77 | +| C.2 | Excluded ITU-T G.9961 capabilities ..... | 78 | +| Appendix I | – Introducing a DC offset when using a PHY layer based on
Recommendation ITU-T G.9960 ..... | 79 | +| Bibliography | ..... | 80 | + +## Recommendation ITU-T G.9991 + +## High-speed indoor visible light communication transceiver – System architecture, physical layer and data link layer specification + +# 1 Scope + +This Recommendation specifies the system architecture and functionality for all components of the physical (PHY) layer and data link layer (DLL) of visible light communication (VLC) transceivers for in-premises applications designed for the high-speed optical wireless transmission of data using visible light and infrared communications. + +Specifically, this Recommendation defines: + +- high-speed VLC system architecture and reference models; +- the physical layer specifications of the different PHY layers accepted by this Recommendation; +- the data link layer specification; and +- the management layer specification. + +# 2 References + +The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. + +- [ITU-T G.9960] Recommendation ITU-T G.9960 (2018), *Unified high-speed wireline-based home networking transceivers – System architecture and physical layer specification*. +- [ITU-T G.9961] Recommendation ITU-T G.9961 (2018), *Unified high-speed wireline-based home networking transceivers – Data link layer specification*. +- [ITU-T G.9963] Recommendation ITU-T G.9963 (2018), *Unified high-speed wireline-based home networking transceivers – Multiple input/multiple output specification*. +- [ITU-T G.9964] Recommendation ITU-T G.9964 (2011), *Unified high-speed wireline-based home networking transceivers – Power spectral density specification*. +- [IEC 62471-5:2015] IEC 62471-5:2015, *Photobiological safety of lamps and lamp systems – Part 5: Image projectors*. + +# 3 Definitions + +## 3.1 Terms defined elsewhere + +This Recommendation uses the following terms defined elsewhere: + +**3.1.1 channel** [ITU-T G.9960]: A transmission path between nodes. One channel is considered to be one transmission path. Logically, a channel is an instance of a communication medium used for the purpose of passing data between two or more nodes. + +- 3.1.2 coding overhead** [ITU-T G.9960]: A part of the overhead used to carry the coding redundancy (such as redundancy bits of error correction coding or cyclic redundancy check (CRC)). +- 3.1.3 data** [ITU-T G.9960]: Bits or bytes transported over the medium or via a reference point that individually convey information. Data includes both user (application) data and any other auxiliary information (overhead, including control, management, etc.). Data does not include bits or bytes that, by themselves, do not convey any information, such as the preamble. +- 3.1.4 data rate** [ITU-T G.9960]: The average number of bits communicated (transmitted) in a unit of time. The usual unit of time for data rate is 1 second. +- 3.1.5 DEVICE\_ID** [ITU-T G.9960]: A unique identifier allocated to a node operating in the domain by the domain master during registration. +- 3.1.6 domain ID** [ITU-T G.9960]: A unique identifier of a domain. +- 3.1.7 domain master (DM)** [ITU-T G.9960]: A node supporting the domain master functionality that manages (coordinates) all other nodes of the same domain (i.e., assigns bandwidth resources and manages priorities). Only one active domain master is allowed in a domain, and all nodes within a domain are managed (coordinated) by a single domain master. +- 3.1.8 inter-domain bridge** [ITU-T G.9960]: A bridging function above the physical layer to interconnect nodes of two different domains. +- 3.1.9 logical (functional) interface** [ITU-T G.9960]: An interface in which the semantic, syntactic, and symbolic attributes of information flows are defined. Logical interfaces do not define the physical properties of signals used to represent the information. It is defined by a set of primitives. +- 3.1.10 net data rate** [ITU-T G.9960]: The data rate available at the A-interface of the transceiver reference model. +- 3.1.11 physical interface** [ITU-T G.9960]: An interface defined in terms of physical properties of the signals used to represent the information transfer. A physical interface is defined by signal parameters such as power (power spectrum density), timing, and connector type. +- 3.1.12 primitives** [ITU-T G.9960]: Basic measures of quantities obtained locally or reported by other nodes of the domain. Performance primitives are basic measurements of performance-related quantities, categorized as events, anomalies and defects. Primitives may also be basic measures of other quantities (e.g., a.c. or battery power). +- 3.1.13 priority** [ITU-T G.9960]: A value assigned to the specific frame(s) that determines the relative importance of transmitting frame(s) during the upcoming opportunity to use the medium. +- 3.1.14 reference point** [ITU-T G.9960]: A location in a signal flow, either logical or physical, that provides a common point for observation and/or measurement of the signal flow. +- 3.1.15 registration** [ITU-T G.9960]: The process used by a node to join the domain. +- 3.1.16 relay node** [ITU-T G.9960]: A node supporting relay functionality that acts as an intermediary node, through which other nodes of the same domain can pass their traffic (data, control, or management). + +## **3.2 Terms defined in this Recommendation** + +This Recommendation defines the following terms: + +- 3.2.1 alien domain**: Any group of non-ITU-T G.9991 nodes connected to the same medium or which operate in close proximity. +- 3.2.2 asymmetrical full duplex transmission**: A type of transmission where a node is transmitting to another node while it is receiving from a different node simultaneously. + +**3.2.3 bandplan:** A specific range of the frequency spectrum that is associated with a domain. The bandplans are confined to the modulation bandwidth of the optical source. Multiple bandplans may be used in the same domain provided that each bandplan used is a subset of the largest bandplan specified for the domain and a superset of the smallest bandplan specified for the domain. The bandplan is defined by a lower frequency and upper frequency. + +**3.2.4 central node:** The node that is transmitting to another node while receiving from a different node simultaneously of the asymmetrical full duplex transmission. + +**3.2.5 client:** An application entity distinguished in the network by its unique address (e.g., MAC address). + +**3.2.6 domain:** An ITU-T G.9991 network comprising the domain master and all those nodes that are registered with the same domain master. In the context of this Recommendation, use of the term "domain" without a qualifier means "ITU-T G.9991 domain". Additional qualifiers (e.g., "VLC") may be added to "domain". + +**3.2.7 downlink:** A unidirectional link from the domain master to one or more end-point nodes. This term only applies to the domain operating in centralized mode. + +**3.2.8 end-point node:** This term is used in this Recommendation according to the context to differentiate between the domain master node functionalities and non-domain master node functionalities. + +**3.2.9 global master (GM):** A function that provides coordination between different domains, and which may also convey management functions initiated by the remote management system to support broadband access. + +NOTE – Definition based on the one given in [ITU-T G.9960]. + +**3.2.10 home network:** A home network consists of one or more domains. In the context of this Recommendation, use of the term "home network" means "ITU-T G.9991 home network". + +**3.2.11 node:** Any network device that contains an ITU-T G.9991 transceiver. In the context of this Recommendation, use of the term "node" without a qualifier means "ITU-T G.9991 node". Additional qualifiers (e.g., "relay") may be added to either "node". + +**3.2.12 primary channel:** The channel between the primary transmitter and the primary receiver of the full duplex transmission. + +**3.2.13 primary receiver:** For an asymmetrical full duplex, the primary receiver is the node to which the central node transmits. For a symmetrical full duplex transmission, the primary receiver is the node that receives a request for the full duplex transmission. + +**3.2.14 primary transmission:** The transmission from the primary transmitter to the primary receiver. + +**3.2.15 primary transmitter:** For an asymmetrical full duplex transmission, the primary transmitter is the central node. For a symmetrical full duplex transmission, the primary transmitter is the node that requests to initiate the full duplex transmission. + +**3.2.16 secondary channel:** The channel between the secondary transmitter and the secondary receiver of the full duplex transmission. + +**3.2.17 secondary receiver:** For an asymmetrical full duplex transmission, the secondary receiver is the central node. For a symmetrical full duplex transmission, the secondary receiver is the node that requests to initiate the full duplex transmission, i.e., the primary transmitter. + +**3.2.18 secondary transmission:** The transmission from the secondary transmitter to the secondary receiver. + +**3.2.19 secondary transmitter:** For an asymmetrical full duplex transmission, the secondary transmitter is the node that transmits the MSG frame to the central node. For a symmetrical full duplex transmission, the secondary transmitter is the node that receives a request for the full duplex transmission, i.e., the primary receiver. + +**3.2.20 subcarrier index modulation:** For this modulation, the positions of used subcarriers in the frequency domain are utilized to transmit extra bits without additional power. + +**3.2.21 symmetrical full duplex transmission:** A type of transmission where a node is transmitting to another node while it is receiving from the same node simultaneously. + +**3.2.22 uplink:** A unidirectional link from an end-point node to the domain master. This term only applies to the domain operating in centralized mode. + +**3.2.23 wavelength band:** A specific range of the wavelength of light that is associated with a domain. Multiple wavelength bands may be used in the same domain. The wavelength band is defined by a lower wavelength and upper wavelength. + +# 4 Abbreviations and acronyms + +This Recommendation uses the following abbreviations and acronyms: + +| | | +|----------|-------------------------------------| +| AAT | Address Association Table | +| ACO-OFDM | Asymmetrically Clipped Optical OFDM | +| AE | Application Entity | +| APC | Application Protocol Convergence | +| APDU | APC Protocol Data Unit | +| AR | Access Request | +| ARQ | Automatic Repeat request | +| ASC | Active Subcarrier | +| BAT | Bit Allocation Table | +| BER | Bit Error Rate | +| CBTS | Contention-Based TS | +| CFTS | Contention-Free TS | +| CFTXOP | Contention-Free TXOP | +| CM | Centralized Mode | +| CRC | Cyclic Redundancy Check | +| CRQ | Collision Resolution Queue | +| CRS | Carrier Sense | +| CW | Contention Window | +| DAP | Domain Access Point | +| DLL | Data Link Layer | +| DM | Domain Master | +| DME | DLL Management Entity | +| DMME | Domain Master Management Entity | +| DQ | Distributed Queueing | + +| | | +|----------|-----------------------------------------------| +| DTQ | Data Transmission Queue | +| EHI | Extended Header Indication | +| EP | End Point | +| FDCFTXOP | Full Duplex Contention-Free TXOP | +| FDI | Full Duplex Indicator | +| FDSTXOP | Full Duplex Shared TXOP | +| FEC | Forward Error Correction | +| FT | Frame Type | +| GM | Global Master | +| GME | Global Master Entity | +| HAN | Home Area Network | +| IR | Infrared | +| ISC | Inactive Subcarrier | +| LAAT | Local Address Association Table | +| LCMP | Layer 2 Configuration and Management Protocol | +| LED | Light Emitting Diode | +| LLC | Logical Link Control | +| LCDU | link Control Data Unit | +| LPDU | LLC Protocol Data Unit | +| LPH | LPDU Header | +| LSB | Least Significant Bit | +| MAC | Medium Access Control | +| MPDU | MAC Protocol Data Unit | +| MAP | Medium Access Plan | +| MCS | Management, Control and Security | +| MDI | Medium-Dependent Interface | +| MIMO | Multiple Input/Multiple Output | +| MP2MP | Multipoint to Multipoint | +| MSB | Most Significant Bit | +| MSC | Masked Subcarrier | +| NME | Node Management Entity | +| NMS | Network Management System | +| OFDM | Orthogonal Frequency Division Multiplexing | +| P2MP | Point To Multipoint | +| P2P | Peer-To-Peer communication | +| PCS | Physical Coding Sub-layer | +| PD | Photodiode | + +| | | +|-------|---------------------------------------| +| PMA | Physical Medium Attachment | +| PMD | Physical Medium Dependent | +| PME | PHY Management Entity | +| PMI | Physical Medium-independent Interface | +| PMSC | Permanently Masked Subcarrier | +| PR | Priority Resolution | +| PSD | Power Spectral Density | +| QoS | Quality of Service | +| RG | Residential Gateway | +| RMSC | Regionally Masked Subcarrier | +| SC | Security Controller | +| SCE | Security Controller Entity | +| SIM | Subcarrier Index Modulation | +| SNR | Signal to Noise Ratio | +| SSC | Supported Subcarrier | +| STXOP | Shared TXOP | +| STW | Secondary Transmission Window | +| TCI | Transmission Channel Indicator | +| TS | Time Slot | +| TXOP | Transmission opportunity | +| UM | Unified Mode | +| VLC | Visible Light Communication | + +# 5 Conventions + +## 5.1 Bit ordering convention + +See clause 5.2.4 of [ITU-T G.9960]. + +# 6 System architecture and reference models + +## 6.1 System architecture + +An architectural model of the ITU-T G.9991 home network is shown in Figure 6-1. This model includes one or more domains and bridges to alien domains such as a PLC or Ethernet home network, or a DSL or PON access network. The global master function coordinates resources such as bandwidth reservations, inter-domain handover and operational characteristics between domains, and may convey the relevant functions initiated by a remote management system to support broadband access. Detailed specification and use of the global master function is specified in clause 6.1.4. The specification of bridges to alien domains and to the access network is beyond the scope of this Recommendation. + +NOTE 1 – Depending on the application, domains could use any topology specified in clause 6.1.1. + +NOTE 2 – It is possible to install multiple ITU-T G.9991 home networks (i.e., not connected by bridges to an alien domain) per dwelling. + +![Figure 6-1: ITU-T G.9991 home network architecture reference model. The diagram shows three domains (Domain 1, Domain 2, Domain S) connected to a central 'Any medium'. Each domain contains a 'Domain master' and one or more 'Nodes'. A 'Global master (logical function)' is shown connected to the 'Any medium'. A 'Bridge to alien domain (not in scope)' is also connected to the 'Any medium'. A legend at the bottom indicates that dashed lines represent 'Optical wireless media (i.e., visible light, infrared)'. The diagram is labeled G.9991(19)_F6-1.](af7916c89a458fdab6c3f443217388ae_img.jpg) + +Figure 6-1: ITU-T G.9991 home network architecture reference model. The diagram shows three domains (Domain 1, Domain 2, Domain S) connected to a central 'Any medium'. Each domain contains a 'Domain master' and one or more 'Nodes'. A 'Global master (logical function)' is shown connected to the 'Any medium'. A 'Bridge to alien domain (not in scope)' is also connected to the 'Any medium'. A legend at the bottom indicates that dashed lines represent 'Optical wireless media (i.e., visible light, infrared)'. The diagram is labeled G.9991(19)\_F6-1. + +**Figure 6-1 – ITU-T G.9991 home network architecture reference model** + +A domain comprises a domain master and may contain one or more nodes registered with it. Nodes in the same domain may connect through different media, i.e., visible light and infrared. The domain master considers bridges to alien domains as application entities (AEs) of a node with certain requirements. + +### 6.1.1 Topology + +While this specification does not preclude the use of ITU-T G.9991 in other topologies, it has been specifically designed to cope with the reference ones described in the following sections. + +#### 6.1.1.1 Peer to peer (or point to point) topology (P2P) + +This topology is represented by Figure 6-2. + +![Figure 6-2: P2P topology. The diagram shows two nodes, N1 and N2, connected by a double-headed arrow, indicating a peer-to-peer relationship. The diagram is labeled G.9991(19)_F6-2.](3ad00ce93ad9dea9ee0f47535e5355e6_img.jpg) + +Figure 6-2: P2P topology. The diagram shows two nodes, N1 and N2, connected by a double-headed arrow, indicating a peer-to-peer relationship. The diagram is labeled G.9991(19)\_F6-2. + +**Figure 6-2 – P2P topology** + +In this topology one of the nodes will act as the domain master (DM) and the other as the end point (EP). + +#### 6.1.1.2 Point to multipoint topology (P2MP) + +This topology, also known as "star" topology, is represented by Figure 6-3. + +![Figure 6-3: P2MP topology. The diagram shows a central node N1 connected to three other nodes, N2, N3, and N4, by double-headed arrows, forming a star topology. The diagram is labeled G.9991(19)_F6-3.](5dfc130b129ace4df375839020a5700d_img.jpg) + +Figure 6-3: P2MP topology. The diagram shows a central node N1 connected to three other nodes, N2, N3, and N4, by double-headed arrows, forming a star topology. The diagram is labeled G.9991(19)\_F6-3. + +**Figure 6-3 – P2MP topology** + +In this topology a node centralizes the communication. This node (usually the DM) is the only one authorized to exchange information with any node in the domain, and the other nodes cannot interact with each other. This is equivalent to the centralized mode (CM) of operation [ITU-T G.9960]. + +#### 6.1.1.3 Multipoint to multipoint (MP2MP) + +This topology, normally also called "mesh", is represented by Figure 6-4. + +![Figure 6-4: MP2MP topology diagram showing five nodes (N1, N2, N3, N4, N5) arranged in two rows. N1 and N2 are at the top, and N3, N4, and N5 are at the bottom. Every node is connected to every other node by a double-headed arrow, representing a fully connected mesh network. The label G.9991(19)_F6-4 is at the bottom right.](a33da0f14e456f92539ce3e9b7d81f9a_img.jpg) + +G.9991(19)\_F6-4 + +Figure 6-4: MP2MP topology diagram showing five nodes (N1, N2, N3, N4, N5) arranged in two rows. N1 and N2 are at the top, and N3, N4, and N5 are at the bottom. Every node is connected to every other node by a double-headed arrow, representing a fully connected mesh network. The label G.9991(19)\_F6-4 is at the bottom right. + +**Figure 6-4 – MP2MP topology** + +In this topology nodes are authorized to talk between themselves; however, visibility may be limited. The MP2MP topology is for further study. + +#### 6.1.1.4 Relayed mode + +This topology is represented by Figure 6-5. + +![Figure 6-5: Relayed topology diagram showing four nodes (N1, N2, N3, N4) arranged in a horizontal line. Each node is connected to the next one by a double-headed arrow, forming a chain. The label G.9991(19)_F6-5 is at the bottom right.](f6e8acf9f931452d01688d311b5c0364_img.jpg) + +G.9991(19)\_F6-5 + +Figure 6-5: Relayed topology diagram showing four nodes (N1, N2, N3, N4) arranged in a horizontal line. Each node is connected to the next one by a double-headed arrow, forming a chain. The label G.9991(19)\_F6-5 is at the bottom right. + +**Figure 6-5 – Relayed topology** + +In this topology, intermediate nodes are used as relay nodes in order to link nodes without direct visibility. + +Details of this mode are for further study. + +#### 6.1.1.5 Centralized topology + +This topology is represented by Figure 6-6. + +![Figure 6-6 – Centralized topology diagram. A central node labeled GM (Global Master) is at the top. Below it, a dashed horizontal line represents the 'M interface'. Below the interface, there are multiple domains. Domain 1 contains nodes N11 (domain master), N12, N13, and N14. Domain 2 contains nodes N21 (domain master), N22, N23, and N24. Domain k contains nodes Nk1 and Nk2 (domain masters), Nk3, Nk4, and Nk5. Solid arrows point from slave nodes (N12, N13, N14, N22, N23, N24, Nk3, Nk4, Nk5) to their respective domain masters (N11, N21, Nk1, Nk2). Dashed arrows point from each domain master (N11, N21, Nk1, Nk2) up to the GM node across the M interface. An ellipsis indicates additional domains between Domain 2 and Domain k. A small label 'G.9991(19)_F6-6' is in the bottom right corner of the diagram area.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg) + +Figure 6-6 – Centralized topology diagram. A central node labeled GM (Global Master) is at the top. Below it, a dashed horizontal line represents the 'M interface'. Below the interface, there are multiple domains. Domain 1 contains nodes N11 (domain master), N12, N13, and N14. Domain 2 contains nodes N21 (domain master), N22, N23, and N24. Domain k contains nodes Nk1 and Nk2 (domain masters), Nk3, Nk4, and Nk5. Solid arrows point from slave nodes (N12, N13, N14, N22, N23, N24, Nk3, Nk4, Nk5) to their respective domain masters (N11, N21, Nk1, Nk2). Dashed arrows point from each domain master (N11, N21, Nk1, Nk2) up to the GM node across the M interface. An ellipsis indicates additional domains between Domain 2 and Domain k. A small label 'G.9991(19)\_F6-6' is in the bottom right corner of the diagram area. + +**Figure 6-6 – Centralized topology** + +In this topology multiple domains operating in P2MP or MP2MP are coordinated by the same global master (see clause 6.1.3). There is no visibility between the nodes and the global master except for the case that the global master is co-located with a node. + +### 6.1.2 Domains + +#### 6.1.2.1 General rules of operation + +A domain, as depicted in Figure 6-1, may include nodes with a range of capabilities including extended capabilities such as relay and domain master. The function of the domain master is to assign and coordinate resources (bandwidth and priorities) of all nodes in its domain. The following rules apply for any domain: + +- 1) A home network may include one or more domains. +- 2) More than one domain may be established over the same medium, for example, by using orthogonal signals over different frequency bands. +- 3) The home network shall have a unique name. All domains of the same home network shall use this name. +- 4) The domain ID shall be used to identify a specific domain. Each domain in a home network shall have a unique domain ID. +- 5) Domains from the same home network established over the same medium may interfere with each other (e.g., if they use the same frequency band). Coordination between domains of the same home network sharing a common medium may be performed. +- 6) All nodes in a domain shall be managed by a single domain master. +- 7) There shall be one and only one active domain master per domain. +- 8) Nodes are not required to be domain master capable. That is, some nodes may not support the functionality necessary to become a domain master. +- 9) The domain master shall assign a DEVICE\_ID to a node during the node's registration process. + +#### 6.1.2.2 Relationship between domain and wavelength bands + +Two wavelength bands are defined in this Recommendation, which are visible light (380 nm-780 nm) and infrared (800 nm-1675 nm). An ITU-T G.9991 domain can be up-converted to any one of the wavelength bands or both. Figure 6-7 shows an example of the relationships between domains and + +wavelength bands. Domain A uses only visible light, Domain B uses only infrared, while Domain C uses both infrared and visible light. + +![Figure 6-7: Relationships between domain and medium. The diagram shows three domains: Domain A, Domain B, and Domain C. Each domain consists of a Domain Master (DM) and an End Point (EP) connected by arrows representing wavelength bands. Domain A shows visible light arrows between DM and EP, labeled 'Wavelength band'. Domain B shows infrared arrows between DM and EP, labeled 'Wavelength band'. Domain C shows both infrared and visible light arrows between DM and EP, labeled 'Wavelength band'. A small note 'G.9991(19)_F6-7' is present below Domain C.](5cab96b2d23174c25919840ecd50aa48_img.jpg) + +Figure 6-7: Relationships between domain and medium. The diagram shows three domains: Domain A, Domain B, and Domain C. Each domain consists of a Domain Master (DM) and an End Point (EP) connected by arrows representing wavelength bands. Domain A shows visible light arrows between DM and EP, labeled 'Wavelength band'. Domain B shows infrared arrows between DM and EP, labeled 'Wavelength band'. Domain C shows both infrared and visible light arrows between DM and EP, labeled 'Wavelength band'. A small note 'G.9991(19)\_F6-7' is present below Domain C. + +**Figure 6-7 – Relationships between domain and medium** + +NOTE – Besides infrared and visible light, other media, e.g., RF may be used for uplink. + +A node may be capable of supporting different wavelength bands. The capabilities of the transmitter and receiver to support different wavelength bands of a node are defined in Table 6-1. + +**Table 6-1 – Capabilities of the transceiver to support different wavelength bands** + +| | | +|--------------------------|----------------------------------------------------------------------------------------------------------| +| Transmitter capabilities | The node is only capable of transmitting visible light signals. | +| | The node is only capable of transmitting infrared signals. | +| | The node is capable of transmitting both visible light and infrared signals. | +| Receiver capabilities | The node is only capable of receiving visible light signals. | +| | The node is only capable of receiving infrared signals. | +| | The node is capable of receiving both visible light and infrared signals using a single photodiode (PD). | +| | The node is capable of receiving both visible light and infrared signals using different PDs. | + +A domain may include multiple classes of nodes that support different wavelength bands. A node can only communicate with another node when they use matched wavelength bands. A node can only join a domain when it supports the capability to receive signals from the domain master or a relay-capable node; meanwhile, the domain master and the relay-capable node shall also support the capability to receive signals from the node. + +#### 6.1.2.3 Modes of operation + +A domain can operate in one of two modes: centralized mode (CM) or unified mode (UM). Different domains within the home network can use different modes of operation, i.e., CM or UM. Broadcast and multicast shall be supported in any domain, independent of their operational mode (CM or UM). + +In CM the domain master can communicate with any end-point node in the domain directly while direct communication between end-point nodes are not allowed. The end-point nodes may communicate with each other through the domain master. A domain operating in CM may support bidirectional communication, broadcast-only (i.e., unidirectional link) and hybrid communication (e.g., using RF for uplink). Figure 6-8 shows the use of CM. + +![Figure 6-8: Domain operating in centralized mode (CM). It shows three sub-diagrams: a) DM connected to EP1 and EP2; b) DM connected to EP1 and EP2; c) DM connected to EP1 and EP2 via a relay node RF. The diagram is labeled G.9991(19)_F6-8.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg) + +Figure 6-8: Domain operating in centralized mode (CM). It shows three sub-diagrams: a) DM connected to EP1 and EP2; b) DM connected to EP1 and EP2; c) DM connected to EP1 and EP2 via a relay node RF. The diagram is labeled G.9991(19)\_F6-8. + +**Figure 6-8 – Domain operating in centralized mode (CM)** + +NOTE – Regarding the bidirectional communication, the transmitter and receiver may use different frequency bands (e.g., visible light communication (VLC) and infrared (IR)). + +In UM any node can communicate with another node directly or indirectly, via other nodes operating as relay nodes. Figure 6-9 shows the use of UM. In the example, the EP3 and DM that are hidden from each other communicate with each other via the relay node (EP2). + +![Figure 6-9: Domain operating in unified mode (UM). It shows a network where DM is connected to EP1 and EP2, EP3 is connected to EP2 and EP4, and EP2 acts as a relay between DM and EP3. The diagram is labeled G.9991(19)_F6-9.](df82d77a0d2637cbf2da9ea920a554fa_img.jpg) + +Figure 6-9: Domain operating in unified mode (UM). It shows a network where DM is connected to EP1 and EP2, EP3 is connected to EP2 and EP4, and EP2 acts as a relay between DM and EP3. The diagram is labeled G.9991(19)\_F6-9. + +**Figure 6-9 – Domain operating in unified mode (UM)** + +Details on UM are for further study. + +### **6.1.3 Node functionality** + +The main functions and capabilities of a node are summarized in Table 6-2. + +**Table 6-2 – Main functions and capabilities of a node** + +| Function | Description and parameters | +|----------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Medium access | Receives, interprets and acts upon the medium access plan (MAP) | +| Support of admission control protocol | Supports admission control protocol | +| Support of operational modes of the domain | Supports the operational mode (CM or UM) used by the domain
Complies with spectrum compatibility settings for the domain | +| Support of medium access rules | Accesses medium using medium access rules coordinated with the domain master | +| Support of security | Supports authentication and encryption key management procedures | +| Collection and reporting of node information | Provides statistics:
– list of visible nodes
– list of addresses (AAT)
– list of capabilities supported by the node
– performance statistics (data rate, error count, time stamps). | + +**Table 6-2 – Main functions and capabilities of a node** + +| Function | Description and parameters | +|----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Request of bandwidth allocation |
  • – Performs flow set up
  • – Requests bandwidth allocations from the domain master in order to meet QoS requirements of flows
| +| Support of retransmissions | Provides acknowledgment and retransmission of data units that were received with error | +| Support of extended capabilities |
  • – Domain master
  • – Domain access point (DAP)
  • – Domain master selection procedure
  • – Security controller (SC)
| +| Support of management | Support node management | +| Support of power saving modes | Support of optional power saving modes: L1, L2, L3, L4 | + +#### **6.1.3.1 Domain master functionality** + +A domain master controls operation of the nodes in the domain. In addition to the node functionality in Table 6-2, the main functions and capabilities of CM and UM domain masters are summarized in Table 6-3 and Table 6-4, respectively. + +**Table 6-3 – Main functions and capabilities of a domain master in CM** + +| Function | Description and parameters | +|----------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Indication of presence | Periodically communicates MAP to all nodes in the domain | +| Admission control | Admits new nodes to the domain
Limits the number of nodes in a domain
Facilitates departure of nodes from the domain | +| Determination of domain operation | Signals the operational mode inside the domain.
Facilitates spectrum compatibility for the domain by assigning relevant limits on:
  • – frequency band
  • – total transmit power (see clause 8.2.4)
  • – PSD mask.
| +| Bandwidth allocation and QoS support | Assigns medium access rules to all nodes of the domain to facilitate support of QoS | +| Monitor status of the domain | Collects statistics of domain operation:
  • – list of nodes in the domain
  • – topology
  • – performance statistics (data rate, error count).
| +| Communication with the global master (for further study) | Coordinates operation of the domain with other domains using the global master function | +| Support of management | Support domain master management | +| Support of power saving modes | Support of power saving modes: L1, L2, L3 and L4 | + +**Table 6-4 – Main functions and capabilities of a domain master in UM mode** + +| Function | Description and parameters | +|----------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Indication of presence | Periodically communicates MAP to all nodes in the domain | +| Admission control | Admits new nodes to the domain
Limits the number of nodes in a domain
Facilitates departure of nodes from the domain | +| Determination of domain operation | Signals the operational mode inside the domain
Supports hidden nodes by assigning MAP repeaters
Facilitates spectrum compatibility for the domain by assigning relevant limits on:
– frequency band
– total transmit power (see clause 8.2.4)
– PSD mask. | +| Bandwidth allocation and QoS support | Assigns medium access rules to all nodes of the domain to facilitate support of QoS | +| Monitor status of the domain | Collects statistics of domain operation:
– list of nodes in the domain
– topology
– performance statistics (data rate, error count). | +| Communication with the global master (for further study) | Coordinates operation of the domain with other domains using the global master function | +| Backup master assignment | Assigning of a backup domain master to take over the domain master role | +| Support of management | Support domain master management | +| Support of power saving modes | Support of power saving modes: L1, L2, L3 and L4 | + +### 6.1.4 Global master function + +See clause 5.1.3 of [ITU-T G.9961]. + +## 6.2 Reference models + +### 6.2.1 Protocol reference model of a VLC system + +The reference model used for ITU-T G.9991 follows the structure presented in clause 5.2.1 of [ITU-T G.9960]. + +Due to the adaptation of ITU-T G.9991 technology to different scenarios, different PHY layers are defined in this Recommendation. However, the DLL layer is common for all devices compliant with this Recommendation. + +A device is compliant with this Recommendation if it implements the common DLL layer and at least one of the PHY layers described in this Recommendation. + +All the different PHY layers described in this Recommendation are compliant to the PMI interface description described in clause 5.2.2.2 of [ITU-T G.9960]. + +Figure 6-10 shows the ITU-T G.9991 protocol reference model. + +![Figure 6-10 – Reference model. This diagram illustrates the functional architecture of a VLC transceiver. On the left, the OSI reference model is shown with layers: NETWORK LAYER, DATA LINK LAYER, and PHYSICAL LAYER. The DATA LINK LAYER is subdivided into MAC, LLC, and APC. The PHYSICAL LAYER is subdivided into PCS, PMA, and PMD. The diagram shows two physical layer implementations: ITU-T G.9960-based PHY and ACO-OFDM PHY. The ITU-T G.9960-based PHY connects to a Transmission medium via MDI1. The ACO-OFDM PHY connects to a Transmission medium via MDI2. Reference points are indicated: A-interface (between Application entity and APC), x1-reference point (between APC and LLC), x2-reference point (between LLC and MAC), PMI (between MAC and PHY), alpha-reference point (between PCS and PMA), and delta-reference point (between PMA and PMD). The diagram is labeled G.9991(19)_F6-10.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg) + +Figure 6-10 – Reference model. This diagram illustrates the functional architecture of a VLC transceiver. On the left, the OSI reference model is shown with layers: NETWORK LAYER, DATA LINK LAYER, and PHYSICAL LAYER. The DATA LINK LAYER is subdivided into MAC, LLC, and APC. The PHYSICAL LAYER is subdivided into PCS, PMA, and PMD. The diagram shows two physical layer implementations: ITU-T G.9960-based PHY and ACO-OFDM PHY. The ITU-T G.9960-based PHY connects to a Transmission medium via MDI1. The ACO-OFDM PHY connects to a Transmission medium via MDI2. Reference points are indicated: A-interface (between Application entity and APC), x1-reference point (between APC and LLC), x2-reference point (between LLC and MAC), PMI (between MAC and PHY), alpha-reference point (between PCS and PMA), and delta-reference point (between PMA and PMD). The diagram is labeled G.9991(19)\_F6-10. + +**Figure 6-10 – Reference model** + +### 6.2.2 Interfaces – functional description + +See clause 5.2.2 of [ITU-T G.9960]. + +#### 6.2.2.1 A-interface + +See clause 5.2.2.1 of [ITU-T G.9960]. + +#### 6.2.2.2 Physical medium-independent interface (PMI) + +See clause 5.2.2.2 of [ITU-T G.9960]. + +#### 6.2.2.3 Medium-dependent interface (MDI) + +Functional characteristics of the MDI are described by two signal flows: + +- transmit signal (TX DATA) is the flow of frames transmitted on to the medium; +- receive signal (RX DATA) is the flow of frames received from the medium. + +The implementation of these two primitives can be different depending on the physical layer used by the VLC device. + +### 6.2.3 Functional model of a VLC transceiver + +The functional model of a VLC transceiver is presented in Figure 6-11. It addresses nodes without extended capabilities, as well as nodes with extended capabilities such as domain master and relaying (including DAP), which differ by their medium access control (MAC), logical link control (LLC) and upper layer functionalities. + +The PHY layer function is dependent on the physical layer implementation but includes all functions necessary to encapsulate MPDUs into PHY frames (e.g. flow control, encapsulation, line coding, etc.). + +Clause 8 of this Recommendation describes the adaptation of an [ITU-T G.9960] PHY layer to the VLC system. Clause 9 of this Recommendation describes a PHY layer based on an asymmetrically clipped optical (ACO-OFDM) approach. + +![Functional model of a VLC transceiver diagram showing layers and interfaces.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg) + +The diagram illustrates the functional model of a VLC transceiver. At the top, 'Data primitives' and 'Control primitives' are shown entering through interface 'A'. Below this, the 'APC', 'LLC', and 'MAC' layers are stacked vertically. To the right of these layers is a 'DLL management' block. Below the MAC layer is the 'PMI' interface. The next layer is 'PHY1 or PHY2', which is connected to another 'DLL management' block on its right. Below the PHY layer is the 'MDI' interface, which connects to 'Tx-Rx frames' and then to the 'Medium'. The diagram is labeled 'G.9991(19)\_F6-11'. + +Functional model of a VLC transceiver diagram showing layers and interfaces. + +**Figure 6-11 – Functional model of a VLC transceiver** + +The detailed description of the functional model of the DLL is specified in clause 10. + +## 6.3 Management-plane model of a VLC system + +Figure 6-12 illustrates data, control and management-plane reference models for an ITU-T G.9991 transceiver. Details of data and control-plane reference models are shown in clause 6.2. The Q-interface provides the interface between the network management systems (NMS) and the node management entity (NME) at a node. The definition of parameters at the Q-interface and the transport of the management instrumentation over the Q-interface are outside the scope of this Recommendation. The X-interface provides the interface between the external dimmer function and the NME. + +![Management-plane reference model diagram showing entities and interfaces.](a24e89a6fe9bb70c83f8bf5202baba95_img.jpg) + +The diagram shows the management-plane reference model. It is divided into three vertical sections: 'Data-plane reference model', 'Control-plane reference model', and 'Management-plane reference model'. The Data-plane contains 'DLL' and 'PHY' blocks. The Control-plane contains 'DLL management entity' and 'PHY management entity' blocks. The Management-plane contains a 'Node management entity' block. The Data-plane and Control-plane are connected by a dashed line labeled 'A-interface'. The Control-plane and Management-plane are also connected by a dashed line labeled 'A-interface'. The Management-plane is connected to a 'Network management entity' (represented by a cloud) via a dashed line labeled 'Q-interface'. Below the Management-plane is an 'X-interface' leading to a 'Dimmer' block. A note at the bottom left states: 'NOTE – The dimmer function is only relevant when using visible light spectrum.' The diagram is labeled 'G.9991(19)\_F6-12'. + +Management-plane reference model diagram showing entities and interfaces. + +**Figure 6-12 – Management-plane reference model** + +# 7 Topology profiles + +Topology profiles are intended to specify nodes with significantly different levels of complexity and functionality. A node shall be classified into particular topology profiles according to its degree of + +complexity and functionality. For compliance with this Recommendation, a node is required to support one topology profile, at a minimum. + +## 7.1 Topology profiles based on the operational modes + +Based on the operational modes (see clause 6.1.2.3), a node shall be classified into two topology profiles: centralized-mode (CM) topology profile and unified-mode (UM) topology profile. A node shall support at least one topology profile. + +A node that supports only CM topology profile is not allowed to be a member of the domain operating in unified mode, while a node that supports only UM topology profile is not allowed to be a member of the domain operating in centralized mode. + +# 8 Physical layer specification I (PHY layer based on ITU-T G.9960) + +## 8.1 Medium independent specification + +### 8.1.1 Functional model of the PHY + +See clause 7.1.1 of [ITU-T G.9960]. + +### 8.1.2 Physical coding sublayer (PCS) + +See clause 7.1.2 of [ITU-T G.9960]. + +#### 8.1.2.1 PHY frame + +See clause 7.1.2.1 of [ITU-T G.9960]. + +#### 8.1.2.2 MPDU mapping + +See clause 7.1.2.2 of [ITU-T G.9960]. + +#### 8.1.2.3 PHY frame header + +See clause 7.1.2.3 of [ITU-T G.9960]. + +##### 8.1.2.3.1 Common part fields + +###### 8.1.2.3.1.1 Frame type (FT) + +The frame type (FT) field is a 4-bit field that indicates the type of PHY frame. + +Table 8-1 describes the PHY-frame types. + +**Table 8-1 – PHY-frame types** + +| Type | Value
(b 3 b 2 b 1 b 0 ) | Description | Reference | +|----------|-------------------------------------------------------------------------|----------------------------------|--------------------| +| MAP/RMAP | 0000 | MAP/RMAP frame | Clause 8.1.2.3.2.1 | +| MSG | 0001 | Data and management frame | Clause 8.1.2.3.2.2 | +| ACK | 0010 | ACK control frame | Clause 8.1.2.3.2.3 | +| RTS | 0011 | RTS control frame | Clause 8.1.2.3.2.4 | +| CTS | 0100 | CTS control frame | Clause 8.1.2.3.2.5 | +| CTMG | 0101 | Short control frame | Clause 8.1.2.3.2.6 | +| PROBE | 0110 | PROBE frame | Clause 8.1.2.3.2.7 | +| ACKRQ | 0111 | ACK retransmission request frame | Clause 8.1.2.3.2.8 | + +**Table 8-1 – PHY-frame types** + +| Type | Value
(b 3 b 2 b 1 b 0 ) | Description | Reference | +|----------|-------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------|--------------------------------------------| +| BMSG | 1000 | Bidirectional MSG frame; contains data and management frames in the payload and ACK | Clause 8.1.2.3.2.9 | +| BACK | 1001 | Bidirectional ACK frame; contains ACK and data and management frames in the payload | Clause 8.1.2.3.2.10 | +| ACTMG | 1010 | Acknowledgment for CTMG frame | Clause 8.1.2.3.2.11 | +| IND | 1011 | Indication frame for distributed queueing (DQ) based contention access mechanism for half duplex MAC | Clause 8.1.2.3.2.12 | +| Reserved | 1100 to 1110 | Reserved by ITU-T | Clause 8.1.2.3.2.13 to Clause 8.1.2.3.2.15 | +| FTE | 1111 | Frame type extension; this frame type is a pointer to a set of additional frame types. | Clause 8.1.2.3.2.16 | + +###### **8.1.2.3.1.2 Domain ID (DOD)** + +See clause 7.1.2.3.1.2 of [ITU-T G.9960]. + +###### **8.1.2.3.1.3 Source ID (SID)** + +See clause 7.1.2.3.1.3 of [ITU-T G.9960]. + +###### **8.1.2.3.1.4 Destination ID (DID)** + +See clause 7.1.2.3.1.4 of [ITU-T G.9960]. + +###### **8.1.2.3.1.5 Multicast indication (MI)** + +See clause 7.1.2.3.1.5 of [ITU-T G.9960]. + +###### **8.1.2.3.1.6 Duration indication (DRI)** + +See clause 7.1.2.3.1.6 of [ITU-T G.9960]. + +###### **8.1.2.3.1.7 Extended header indication (EHI)** + +If the EHI field is set to one, the PHY frame header shall contain $2 \times \text{PHY}_H$ information bits. The additional $\text{PHY}_H$ information bits of the extended part of the PHY-frame header are specified in clause 8.1.2.3.3. If the EHI field is set to zero, the PHY-frame header shall contain $\text{PHY}_H$ information bits. The EHI field shall be set according to the frame type as shown in Table 8-2. + +**Table 8-2 – Value of EHI for different frame types** + +| Frame type | Value of EHI | +|------------|--------------| +| MAP/RMAP | zero | +| MSG | zero or one | +| ACK | zero or one | +| RTS | zero | +| CTS | zero | + +**Table 8-2 – Value of EHI for different frame types** + +| Frame type | Value of EHI | +|------------|--------------| +| PROBE | zero | +| ACKRQ | zero | +| BMSG | zero or one | +| BACK | zero or one | +| CTMG | zero or one | +| FTE | zero or one | +| ACTMG | zero | +| IND | zero | + +###### 8.1.2.3.1.8 Header segmentation indication (HSI) + +See clause 7.1.2.3.1.8 of [ITU-T G.9960]. + +###### 8.1.2.3.1.9 Header check sequence (HCS) + +See clause 7.1.2.3.1.9 of [ITU-T G.9960]. + +##### 8.1.2.3.2 Variable part fields + +See clause 7.1.2.3.2 of [ITU-T G.9960]. + +###### 8.1.2.3.2.1 MAP and RMAP PHY-frame type specific fields + +See clause 7.1.2.3.2.1 of [ITU-T G.9960]. + +###### 8.1.2.3.2.2 MSG PHY-frame type specific fields + +Table 8-3 lists the PHY-frame header fields specific to the MSG frame type. + +**Table 8-3 – MSG PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|--------------|---------|--------|---------------------------------------------------------------|-----------------------| +| MSG_DUR | 0 and 1 | [15:0] | Duration for MSG frame | Clause 8.1.2.3.2.2.1 | +| BLKSZ | 2 | [1:0] | Block size of FEC codeword for MSG frame payload | Clause 8.1.2.3.2.2.2 | +| FEC_RATE | | [4:2] | FEC coding rate for MSG frame payload | Clause 8.1.2.3.2.2.3 | +| REP | | [7:5] | Number of repetitions used for encoding the MSG frame payload | Clause 8.1.2.3.2.2.4 | +| FCF | 3 | [2:0] | FEC concatenation factor | Clause 8.1.2.3.2.2.5 | +| SI | | [6:3] | Scrambler initialization | Clause 8.1.2.3.2.2.6 | +| MDET | | [7] | Master is detected | Clause 8.1.2.3.2.2.7 | +| BAT_ID | 4 | [4:0] | Bit allocation table identifier | Clause 8.1.2.3.2.2.8 | +| BNDPL/GRP_ID | | [7:5] | Bandplan identifier/subcarrier grouping identifier | Clause 8.1.2.3.2.2.9 | +| GI_ID | 5 | [2:0] | Guard interval identifier | Clause 8.1.2.3.2.2.10 | + +**Table 8-3 – MSG PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|------------------|----------|--------|-------------------------------------------------------------------------|-------------------------------------------| +| APSDC-M | | [7:3] | Actual PSD ceiling of MSG frame | Clause 8.1.2.3.2.2.11 | +| CONNECTION_ID | 6 | [7:0] | Connection identifier | Clause 8.1.2.3.2.2.12 | +| RPRQ | 7 | [1:0] | Reply required | Clause 8.1.2.3.2.2.13 | +| BRSTCnt | | [3:2] | Burst frame count | Clause 8.1.2.3.2.2.14 | +| BEF | | [4] | Burst end flag | Clause 8.1.2.3.2.2.15 | +| AIFG_IND | | [5] | AIFG indication | Clause 8.1.2.3.2.2.16 | +| Reserved | | [6] | Reserved | Reserved for use by ITU-T G.9963 (Note 1) | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note 1) | +| ACE_SYM | 8 | [2:0] | Number of ACE symbols | Clause 8.1.2.3.2.2.18 | +| CNN_MNGMT | | [6:3] | Connection management | Clause 8.1.2.3.2.2.19 | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note 1) | +| BRURQ | 9 and 10 | [15:0] | Bandwidth reservation update request | Clause 8.1.2.3.2.2.20 (Note 2) | +| START_SSN | 9 and 10 | [15:0] | Start segment sequence number | Clause 8.1.2.3.2.2.21 (Note 3) | +| CURRTS | 11 | [6:0] | Current TS | Clause 8.1.2.3.2.2.22 | +| BTXRQ | | [7] | Request for bidirectional transmission | Clause 8.1.2.3.2.2.23 | +| NUM_MCACK_SLOTS | 12 | [2:0] | Number of Mc-ACK slots | Clause 8.1.2.3.2.2.24 | +| ADVISED_WIN_SIZE | | [7:3] | In connection establishment this field may specify advised window size. | Clause 8.1.2.3.2.2.25 (Note 4) | +| FDI | 13 | [0] | Full duplex indication | Clause 8.1.2.3.2.2.17 | +| Reserved | | [7:1] | Reserved | Reserved by ITU-T (Note 1) | +| Reserved | 14 | [7:0] | Reserved | Reserved by ITU-T (Note 1) | + +NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. +NOTE 2 – The BRURQ field is defined when the START\_SSN field is not defined (see Note 3). +NOTE 3 – The START\_SSN field is defined only when CNN\_MNGMT = 0001, CNN\_MNGMT = 0011, CNN\_MNGMT = 0101 or CNN\_MNGMT = 0111. Otherwise, the meaning of this field is BRURQ. +NOTE 4 – The ADVISED\_WIN\_SIZE field is defined only when CNN\_MNGMT = 0101, otherwise these bits are reserved by ITU-T and shall be set to zero by the transmitter and ignored by the receiver. + +###### 8.1.2.3.2.2.1 Duration for MSG frame (MSG\_DUR) + +See clause 7.1.2.3.2.2.1 of [ITU-T G.9960]. + +###### 8.1.2.3.2.2.2 Block size (BLKSZ) + +See clause 7.1.2.3.2.2.2 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.3 FEC coding rate (FEC\_RATE)** + +See clause 7.1.2.3.2.2.3 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.4 Repetitions (REP)** + +See clause 7.1.2.3.2.2.4 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.5 FEC concatenation factor (FCF)** + +See clause 7.1.2.3.2.2.5 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.6 Scrambler initialization (SI)** + +See clause 7.1.2.3.2.2.6 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.7 Master is detected indication (MDET)** + +See clause 7.1.2.3.2.2.7 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.8 Bit allocation table identifier (BAT\_ID)** + +See clause 7.1.2.3.2.2.8 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.9 Bandplan identifier/subcarrier grouping identifier (BNDPL/GRP\_ID)** + +See clause 7.1.2.3.2.2.9 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.10 Guard interval identifier (GI\_ID)** + +See clause 7.1.2.3.2.2.10 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.11 Actual PSD ceiling of MSG frame (APSDC-M)** + +See clause 7.1.2.3.2.2.11 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.12 Connection identifier (CONNECTION\_ID)** + +See clause 7.1.2.3.2.2.12 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.13 Reply required (RPRQ)** + +See clause 7.1.2.3.2.2.13 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.14 Burst frame count (BRSTCnt)** + +See clause 7.1.2.3.2.2.14 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.15 Burst end flag (BEF)** + +See clause 7.1.2.3.2.2.15 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.16 AIFG indication (AIFG\_IND)** + +See clause 7.1.2.3.2.2.16 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.17 Full duplex indicator (FDI)** + +The FDI field shall indicate whether the frame header of this MSG frame contains the secondary transmission information. If the 'FDI' bit is set to one, the extended frame header of the MSG frame shall contain the secondary transmission information. The 'FDI' bit in the frame header of the MSG frames belonging to the primary transmission of the full duplex transmission in the FDSTXOP shall be set to one. + +###### **8.1.2.3.2.2.18 ACE symbols (ACE\_SYM)** + +See clause 7.1.2.3.2.2.17 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.19 Connection management (CNN\_MNGMT)** + +See clause 7.1.2.3.2.2.18 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.20 Bandwidth reservation update request (BRURQ)** + +See clause 7.1.2.3.2.2.19 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.21 Start segment sequence number (START\_SSN)** + +See clause 7.1.2.3.2.2.20 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.22 Current TS (CURRTS)** + +See clause 7.1.2.3.2.2.21 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.23 Request for bidirectional transmission (BTXRQ)** + +See clause 7.1.2.3.2.2.22 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.24 Number of Mc-ACK slots (NUM\_MCACK\_SLOTS)** + +See clause 7.1.2.3.2.2.23 of [ITU-T G.9960]. + +###### **8.1.2.3.2.2.25 Advised Window Size (ADVISED\_WIN\_SIZE)** + +See clause 7.1.2.3.2.2.24 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3 ACK PHY-frame type specific fields** + +Table 8-4 lists the PHY-frame header fields specific to the core part of the PHY-frame header of the ACK frame type. + +**Table 8-4 – ACK PHY frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|-------------|-------|-------|----------------------------------------------------------------------------------------------------|-----------------------| +| FLCTRL_CONN | 0 | [0] | Flow control connection flag | Clause 8.1.2.3.2.3.1 | +| FLCTRLT | | [1] | Flow control type | Clause 8.1.2.3.2.3.2 | +| FLCTRL | | [6:2] | Flow control | Clause 8.1.2.3.2.3.3 | +| FLCTRL_EXT | | [7] | Flow control extension | Clause 8.1.2.3.2.3.14 | +| RXRST_DATA | 1 | [0] | Data RX reset flag | Clause 8.1.2.3.2.3.5 | +| RXRST_MNGMT | | [1] | Management RX reset flag | Clause 8.1.2.3.2.3.6 | +| BAD_BURST | | [2] | Bad burst indication | Clause 8.1.2.3.2.3.7 | +| BTXRQ | | [3] | Request for bidirectional transmission | Clause 8.1.2.3.2.3.4 | +| EXTACKRQ | | [4] | Request for extended acknowledgement | Clause 8.1.2.3.2.3.13 | +| FDI | | [6:5] | Full duplex indicator | Clause 8.1.2.3.2.3.8 | +| TCI | | [7] | Transmission channel indicator, has applicable information only if the 'FDI' field is set to '10'. | Clause 8.1.2.3.2.3.9 | + +**Table 8-4 – ACK PHY frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|----------------------------------|---------|---------|----------------------------------------------------------------------------------|----------------------------| +| ACK_CE_CTRL/
RX_CONN_WIN_SIZE | 2 | [6:0] | ACK channel estimation control/Receiver window size for the connection. (Note 1) | Clause 8.1.2.3.2.3.10 | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note 2) | +| ACKDATA/MCACK_D | 3 to 14 | [90:0] | Acknowledgement data and Mc-ACK descriptor | Clause 8.1.2.3.2.3.11 | +| CRQLength | | [94:91] | The length of the CRQ | Clause 8.1.2.3.2.3.12 | +| Reserved | | [95] | Reserved | Reserved by ITU-T (Note 2) | + +NOTE 1 – This field is interpreted as RX\_CONN\_WIN\_SIZE only when the ACK frame is sent as a reply for an MSG frame requesting the set-up of either a data or a management connection (i.e., when CNN\_MNGMT in the MSG frame for connection set-up is 01012 or 00012). + +NOTE 2 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +###### **8.1.2.3.2.3.1 Flow control connection flag (FLCTRL\_CONN)** + +See clause 7.1.2.3.2.3.1 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.2 Flow control type (FLCTRLT)** + +See clause 7.1.2.3.2.3.2 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.3 Flow control (FLCTRL)** + +See clause 7.1.2.3.2.3.3 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.4 Request for bidirectional transmission (BTXRQ)** + +See clause 7.1.2.3.2.3.4 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.5 Data RX reset flag (RXRST\_DATA)** + +See clause 7.1.2.3.2.3.5 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.6 Management RX reset flag (RXRST\_MNGMT)** + +See clause 7.1.2.3.2.3.6 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.7 Bad burst indication (BAD\_BURST)** + +See clause 7.1.2.3.2.3.7 of [ITU-T G.9960]. + +###### **8.1.2.3.2.3.8 Full duplex indicator (FDI)** + +The FDI field shall indicate whether the frame is an ACK frame that includes the feedback notification for the full duplex transmission in FDSTXOP, or an ACK frame for the half duplex transmission in the CBTXOP as described in clause 10.2.2.3.8, or a regular ACK frame without extra indication. It is a 2-bit field that shall be coded as shown in Table 8-5. + +**Table 8-5 – Interpretation of the FDI field** + +| FDI value
(b 6 b 5 ) | Interpretation | +|-----------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| 00 | The ACK frame is a regular ACK frame without extra indication. | +| 01 | The feedback notification for the full duplex transmission in the FDSTXOP shall be encapsulated in the frame header of the ACK frame, and the acknowledgement data in the ACK frame shall be the acknowledgement to the MSG frame sent by the secondary transmitter identified by the 'HeadDTQ' on the transmission channel in the STW. | +| 10 | The frame is an ACK frame for the half duplex transmission in a CBTXOP (see clause 10.2.2.3.8), and the acknowledgement data in the ACK frame shall be the acknowledgement to the MSG frame sent by the node identified by the 'HeadDTQ' on the transmission channel | +| 11 | Reserved by ITU-T | + +If the FDI field is set to '01', the 'ACKDATA' field in the ACK frame shall indicate the reception status of the MSG frame sent on the transmission channel in the STW. If the FDI field is set to '10', the 'ACKDATA' field in the ACK frame shall indicate the reception status of the MSG frame sent on the transmission channel if there is a transmission channel in the STW. + +###### 8.1.2.3.2.3.9 Transmission channel indicator (TCI) + +The TCI field shall indicate whether the next TS shall contain a transmission channel or not. If this field is set to one, the next TS shall contain a transmission channel after the access channel; otherwise, if this field is set to zero, the next TS shall not contain a transmission channel. + +This field has applicable information only when the 'FDI' field is set to '10'. + +###### 8.1.2.3.2.3.10 ACK channel estimation control/Receiver window size for the connection (ACK\_CE\_CTRL/RX\_CONN\_WIN\_SIZE) + +See clause 7.1.2.3.2.3.8 of [ITU-T G.9960]. + +###### 8.1.2.3.2.3.11 Acknowledgement data and Mc-ACK descriptor (ACKDATA/MCACK\_D) + +See clause 7.1.2.3.2.3.9 of [ITU-T G.9960]. + +###### 8.1.2.3.2.3.12 CRQ length (CRQLength) + +The 'CRQLength' field shall indicate the value of the length of the CRQ, which is the number of collisions left to be resolved. One collision corresponds to one contention slot where at least two candidate secondary transmitters have sent their ARs and the collision has not been resolved yet. It shall be represented as a 4-bit unsigned integer with valid values in the range from 0 to 15. When calculating the length of the CRQ, the collisions newly occurred in the current STW have been taken into account. + +###### 8.1.2.3.2.3.13 Extended ACK Requested (EXTACKRQ) + +See clause 7.1.2.3.2.3.10 of [ITU-T G.9960]. + +###### 8.1.2.3.2.3.14 Flow control extension (FLCTRL\_EXT) + +See clause 7.1.2.3.2.3.11 of [ITU-T G.9960]. + +###### 8.1.2.3.2.4 RTS PHY-frame type specific fields + +Table 8-6 lists the PHY-frame header fields specific to the RTS frame type. + +**Table 8-6 – RTS PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|----------|---------|--------|------------------------|--------------------------| +| RTS_DUR | 0 and 1 | [15:0] | Duration for RTS frame | Clause 8.1.2.3.2.4.1 | +| CID | 2 | [7:0] | CTS proxy ID | Clause 8.1.2.3.2.4.2 | +| CURRTS | 3 | [6:0] | Current TS | Clause 8.1.2.3.2.4.3 | +| Reserved | | [7] | Reserved | Reserved by ITU-T (Note) | +| FDI | 4 | [1:0] | Full duplex indicator. | Clause 8.1.2.3.2.4.4 | +| Reserved | | [7:2] | Reserved | Reserved by ITU-T (Note) | +| Reserved | 5 to 14 | [87:0] | Reserved | Reserved by ITU-T (Note) | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +###### 8.1.2.3.2.4.1 Duration for RTS frame (RTS\_DUR) + +See clause 7.1.2.3.2.4.1 of [ITU-T G.9960]. + +###### 8.1.2.3.2.4.2 CTS proxy ID (CID) + +See clause 7.1.2.3.2.4.2 of [ITU-T G.9960]. + +###### 8.1.2.3.2.4.3 Current TS (CURRTS) + +See clause 7.1.2.3.2.4.3 of [ITU-T G.9960]. + +###### 8.1.2.3.2.4.4 Full duplex Indicator (FDI) + +The FDI field shall indicate whether this RTS frame is an AR frame in the case of the full duplex transmission in the FDSTXOP, or an AR frame for the half duplex transmission in the CBTXOP as described in clause 10.2.2.3.8, or is a regular RTS frame. It is a 2-bit field that shall be coded as shown in Table 8-7. + +**Table 8-7 – Interpretation of the FDI field** + +| FDI value (b 1 b 0 ) | Interpretation | +|--------------------------------------------|-------------------------------------------------------------------------------------| +| 00 | The RTS frame is a regular RTS frame | +| 01 | The RTS is an access request (AR) frame for full duplex transmission in the FDSTXOP | +| 10 | The RTS is an access request (AR) frame for transmission in the CBTXOP | +| 11 | Reserved by ITU-T | + +###### 8.1.2.3.2.5 CTS PHY-frame type specific fields + +See clause 8.1.2.3.2.5 of [ITU-T G.9960]. + +###### 8.1.2.3.2.6 CTMG PHY-frame type specific fields + +See clause 7.1.2.3.2.6 of [ITU-T G.9960]. + +###### 8.1.2.3.2.7 PROBE PHY-frame type specific fields + +See clause 7.1.2.3.2.7 of [ITU-T G.9960]. + +###### 8.1.2.3.2.8 ACKRQ PHY frame type specific fields + +See clause 7.1.2.3.2.8 of [ITU-T G.9960]. + +###### 8.1.2.3.2.9 BMSG PHY-frame type specific fields + +See clause 7.1.2.3.2.9 of [ITU-T G.9960]. + +###### 8.1.2.3.2.10 BACK PHY-frame type specific fields + +See clause 7.1.2.3.2.10 of [ITU-T G.9960]. + +###### 8.1.2.3.2.11 ACTMG PHY-frame type specific fields + +See clause 7.1.2.3.2.11 of [ITU-T G.9960]. + +###### 8.1.2.3.2.12 IND PHY-frame type specific fields + +Table 8-9 lists the PHY-frame header specific fields to the core part of the PHY-frame header of the IND frame type. + +**Table 8-8 – IND PHY-frame type specific fields** + +| Field | Octet | Bits | Description | Reference | +|----------|----------|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------| +| Node [0] | 0 | [7:0] | The DEVICE_ID of the node that has sent an AR that has been received successfully by the central node in contention slot 1 of the access channel. (Note 1). | Clause 8.1.2.3.2.12.1 | +| Node[1] | 1 | [7:0] | The DEVICE_ID of the node that has sent an AR that has been received successfully by the central node in contention slot 2 of the access channel. (Note 1). | Clause 8.1.2.3.2.12.1 | +| Node [2] | 2 | [7:0] | The DEVICE_ID of the node that has sent an AR that has been received successfully by the central node in contention slot 3 of the access channel. (Note 1). | Clause 8.1.2.3.2.12.1 | +| Reserved | 3 and 14 | [95:0] | Reserved | Reserved by ITU-T (Note 2) | + +NOTE 1 – This field shall be ignored if contention slot i of the access channel is not indicated as "successful" in the ACK frame. +NOTE 2 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +###### 8.1.2.3.2.12.1 Node [i] + +The Node [i] (i= 1, 2, 3) field shall indicate the DEVICE\_ID of the node which has sent an AR that has been received successfully by the DM in the contention slot i of the access channel when the DQ-based contention access mechanism specified in clause 10.2.2.3.8 is implemented in a CBTXOP. If contention slot i is indicated as "idle" or "collision" by the DM, Node [i] field in the IND frame shall be set to 0xFF and be ignored by the receiver. + +###### 8.1.2.3.2.13 Reserved + +Reserved by ITU-T. + +###### 8.1.2.3.2.14 Reserved + +Reserved by ITU-T. + +###### 8.1.2.3.2.15 Reserved + +Reserved by ITU-T. + +###### 8.1.2.3.2.16 FTE PHY-frame type specific fields + +See clause 8.1.2.3.2.16 of [ITU-T G.9960]. + +##### 8.1.2.3.3 Extended header fields + +See clause 7.1.2.3.3 of [ITU-T G.9960]. + +###### 8.1.2.3.3.1 Extended header frame-type specific fields (E\_FTSF) + +###### 8.1.2.3.3.1.1 E\_FTSF for a PHY frame + +If the 'EHI' field in the PHY-frame header of an MSG frame is set to one, the MSG frame shall include an extended PHY-frame header. If the 'FDI' field in the PHY frame header of an MSG frame is set to one, the 'E\_FTSF' field shall convey the secondary transmission information as described in clause 10.2.2.5. + +Table 8-9 lists the E\_FTSF for a PHY frame. + +**Table 8-9 – E\_FTSF for an MSG PHY frame type** + +| Field | Octet | Bits | Description | Reference | +|-----------------------|-------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------| +| End_Time | 0-1 | [15:0] | The latest end time of the secondary transmission | Clause 8.1.2.3.3.1.1.1 | +| EmptyCRQFlag | 2 | [0] | Whether the CRQ is empty or not
"0" indicates an empty CRQ
"1" indicates an non-empty CRQ | Clause 8.1.2.3.3.1.1.2 | +| NumberContentionSlots | | [1] | The number of contention slots in the access channel.
"0" indicates no access channel
"1" indicates a access channel with three contention slots | Clause 8.1.2.3.3.1.1.3 | +| Reserved | | [7:2] | Reserved | Reserved by ITU-T (Note 2) | +| HeadDTQ | | [7:0] | The DEVICE_ID of the secondary transmitter in the head of the DTQ | Clause 8.1.2.3.3.1.1.4 | +| NewSecTx[1] | 3 | [7:0] | The DEVICE_ID of the secondary transmitter that has sent an AR that has been received successfully by the central node in contention slot 1 of the previous access channel. (Note 1) | Clause 8.1.2.3.3.1.1.5 | +| NewSecTx[2] | 4 | [7:0] | The DEVICE_ID of the secondary transmitter that has sent an AR that has been received successfully by the central node in contention slot 2 of the previous access channel. (Note 1) | Clause 8.1.2.3.3.1.1.5 | +| NewSecTx[3] | 5 | [7:0] | The DEVICE_ID of the secondary transmitter that has sent an AR that has been received successfully by the central node in contention slot 3 of the previous access channel. (Note 1) | Clause 8.1.2.3.3.1.1.5 | + +**Table 8-9 – E\_FTSF for an MSG PHY frame type** + +| Field | Octet | Bits | Description | Reference | +|------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|---------|-------------|-------------------------------| +| Reserved | 4-18 | [128:0] | Reserved | Reserved by ITU-T
(Note 2) | +| NOTE 1 – This field shall be ignored if contention slot 1 of the previous access channel is not indicated as "successful" in the previous feedback notification. | | | | | +| NOTE 2 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | | + +###### 8.1.2.3.3.1.1.1 Ending time of the STW (Ending\_Time) + +The Ending\_Time field shall indicate the latest time no later than which the transmission of the MSG frame sent by the secondary transmitter to the central node shall end. The Ending\_Time should not exceed the ending time of the MSG frame sent by the central node to the primary receiver on the primary channel. It represents the time shift counted from the beginning of the current STW in TIME\_UNIT units where the size of a TIME\_UNIT is equal to the base TICK size multiplied by a constant factor defined in the MAP header. The values of TICK are defined in Table 10-1. + +###### 8.1.2.3.3.1.1.2 Empty CRQ flag (EmptyCRQFlag) + +The EmptyCRQFlag field shall indicate the candidate secondary transmitters that are allowed to send ARs to the central node by indicating whether the CRQ is empty or not. If the 'EmptyCRQFlag' field indicates the CRQ is empty, all candidate secondary transmitters identified by the FD contention group information extension are allowed to send ARs to the central node; otherwise, only the candidate secondary transmitters belonging to the head of the CRQ are allowed to send ARs to the central node. + +###### 8.1.2.3.3.1.1.3 Number of contention slots (NumberContentionSlots) + +This field is used to indicate the configuration of the secondary channel which could include an access channel or not. If there is an access channel on the secondary channel, then there are three contention slots in the STW; otherwise, if there is no access channel on the secondary channel, there is no contention slots in the STW. + +The number of contention slots which could be three or zero. If the central node determines that there is not enough time to transmit all of the accumulated MSG frames of the secondary transmitters in the DTQ by the end of the FDSTXOP, then the central node shall indicate there is no contention slot in the STW by setting the 'NumberContentionSlots' field to zero; otherwise, there are three contention slots in the STW. + +###### 8.1.2.3.3.1.1.4 Head of the DTQ (HeadDTQ) + +The HeadDTQ field shall indicate the DEVICE\_ID of the secondary transmitter that is scheduled to send an MSG frame to the central node on the transmission channel in the STW. According to the rule of first come first served, the oldest secondary transmitter that is pending to send the MSG frame on the transmission channel should be the head of the DTQ. + +###### 8.1.2.3.3.1.1.5 New secondary transmitter (NewSecTx[i]) + +The NewSecTx[i] (i=1, 2, 3) field shall indicate the DEVICE\_ID of the secondary transmitter which has sent an AR that has been received successfully by the central node in contention slot i of the previous access channel. This field shall be set to 0xFF and be ignored if contention slot i of the previous access channel is not indicated as "successful" in the previous feedback notification. + +###### 8.1.2.3.3.1.2 E\_FTSF for a CTMG PHY frame + +See clause 7.1.2.3.3.1.1 of [ITU-T G.9960]. + +###### 8.1.2.3.3.1.3 E\_FTSF for a BMSG PHY frame + +See clause 7.1.2.3.3.1.2 of [ITU-T G.9960]. + +###### 8.1.2.3.3.1.4 E\_FTSF for a BACK PHY frame + +See clause 7.1.2.3.3.1.3 of [ITU-T G.9960]. + +###### 8.1.2.3.3.1.5 E\_FTSF for ACK PHY frame + +If the 'FDI' field in the ACK PHY-frame type specific field is set to '01', the E\_FTSF for ACK PHY frame shall convey the 'DTQLength' information and the 'status' information for the full duplex transmission in the FDSTXOP. If the 'FDI' field in the ACK PHY-frame type specific field is set to '10', the E\_FTSF for ACK PHY frame shall convey the 'DTQLength' information and the 'status' information for the transmission in CBTXOP as described in clause 10.2.2.3.8. + +Table 8-10 lists the E\_FTSF for the ACK PHY frame. + +**Table 8-10 – E\_FTSF for ACK PHY frame type** + +| Field | Octet | Bits | Description | Reference | +|-----------|---------|---------|-----------------------------------------------|------------------------| +| ACKI_EXT | 0 to 17 | [143:0] | ACKI field extension | Clause 8.1.2.3.3.1.5.1 | +| DTQLength | 18 | [2:0] | The length of the DTQ | Clause 8.1.2.3.3.1.5.2 | +| Status | | [7:3] | The status of the contention slots in the STW | Clause 8.1.2.3.3.1.5.3 | + +###### 8.1.2.3.3.1.5.1 ACKI field extension (ACKI\_EXT) + +See clause 7.1.2.3.3.1.4.1 of [ITU-T G.9960]. + +###### 8.1.2.3.3.1.5.2 DTQ length (DTQLength) + +The 'DTQLength' field shall indicate the number of secondary transmitters that have sent the ARs to the central node successfully and line up the DTQ to send the MSG frames to the central node. It shall be represented as a 4-bit unsigned integer with valid values in the range from 0 to 15. + +When calculating the length of the DTQ, the newly arrived secondary transmitters which have successfully sent the ARs in the access channel have been taken into account. + +###### 8.1.2.3.3.1.5.3 Status + +This field shall indicate the status of the contention slots in the access channel. This field shall be coded as shown in Table 8-11, with 'S' representing 'successful', 'C' representing 'collision' and 'I' representing 'idle'. + +**Table 8-11 – Format of the Status field** + +| Status value
(b 7 b 6 b 5 b 4 b 3 ) | Status of contention
slot 1 | Status of contention
slot 2 | Status of contention
slot 3 | +|-----------------------------------------------------------------------------------------------|--------------------------------|--------------------------------|--------------------------------| +| 00000 | S | S | S | +| 00001 | S | S | C | +| 00010 | S | S | I | +| 00011 | S | C | S | +| 00100 | S | C | C | + +**Table 8-11 – Format of the Status field** + +| Status value
(b 7 b 6 b 5 b 4 b 3 ) | Status of contention
slot 1 | Status of contention
slot 2 | Status of contention
slot 3 | +|-----------------------------------------------------------------------------------------------|--------------------------------|--------------------------------|--------------------------------| +| 00101 | S | C | I | +| 00110 | S | I | S | +| 00111 | S | I | C | +| 01000 | S | I | I | +| 01001 | C | S | S | +| 01010 | C | S | C | +| 01011 | C | S | I | +| 01100 | C | C | S | +| 01101 | C | C | C | +| 01110 | C | C | I | +| 01111 | C | I | S | +| 10000 | C | I | C | +| 10001 | C | I | I | +| 10010 | I | S | S | +| 10011 | I | S | C | +| 10100 | I | S | I | +| 10101 | I | C | S | +| 10110 | I | C | C | +| 10111 | I | C | I | +| 11000 | I | I | S | +| 11001 | I | I | C | +| 11010 | I | I | I | +| 11011~11111 | Reserved | Reserved | Reserved | + +### 8.1.3 Physical medium attachment (PMA) sublayer + +See clause 7.1.3 of [ITU-T G.9960]. + +### 8.1.4 Physical medium dependent (PMD) sublayer + +The functional model of the PMD is presented in Figure 8-1. In the transmit direction, the tone mapper divides the incoming symbol frames of the header and payload into groups of bits and associates each group of bits with a specific subcarrier onto which this group shall be loaded, as specified in clause 8.1.4.2. The constellation encoder converts each incoming group of bits into a complex number that represents the constellation point for this subcarrier. The constellation mapping process is described in clause 8.1.4.3. The unloaded supported subcarriers are modulated by a pseudo-random bit sequence generated as described in clause 8.1.4.2. + +![Functional model of the PMD diagram showing TX and RX symbol frame processing paths, including bit generators, tone mappers, constellation encoders, OFDM modulators, and a medium-specific AFE connected to the MDI and Medium. It also shows PHY management and PMD control data interfaces.](e451401f8fa77b466f401d5fce15b26c_img.jpg) + +The diagram illustrates the functional model of the PMD. On the left, the TX (transmit) path starts with 'TX symbol frames' entering a dashed box labeled 'δ-reference point'. Inside, the frames are processed by a 'Bit generator for unused subcarriers' and a 'Tone mapper', then a 'Constellation mapper and scaler', followed by 'Preamble generation' and a 'Constellation scrambler', and finally an 'OFDM modulator'. The output of the OFDM modulator goes to a 'Medium-specific AFE', which is connected to the 'MDI' (indicated by a dashed line) and the 'Medium'. On the right, the RX (receive) path starts from the 'Medium' through the 'Medium-specific AFE', then to a 'Symbol frames recovery' block containing a 'Constellation decoder', 'Demodulator', and 'Preamble processing and carrier sense generation'. This block outputs 'RX symbol frames' above the 'δ-reference point' dashed line. Both TX and RX paths have 'PMD control data' lines connecting them to a vertical 'PHY management' line on the far right. The diagram is labeled 'G.9991(19)\_F8-1' at the bottom right. + +Functional model of the PMD diagram showing TX and RX symbol frame processing paths, including bit generators, tone mappers, constellation encoders, OFDM modulators, and a medium-specific AFE connected to the MDI and Medium. It also shows PHY management and PMD control data interfaces. + +**Figure 8-1 – Functional model of the PMD** + +The OFDM modulator (clause 8.1.4.4) converts the stream of the $N$ complex numbers at its input into the stream of $N$ complex valued time-domain samples. After adding the preamble, the transmit signal is up-shifted by $F_{US}$ . The real part of the resultant signal is transmitted on to the medium. Parameters of the preamble (clause 8.1.4.5) are determined by the PHY management and depend on the type of the transmitted PHY frame. + +Frames are output on to the medium with inter-frame gaps. + +In the receive direction, the frames incoming from the medium are demodulated and decoded. The recovered symbol frames are transferred to the PMA via the $\delta$ -reference point. The preamble is processed and preamble data are passed to the PHY management entity. + +An amplitude constant (DC offset) signal is added to the modulated signal in order to work within the LED operating range. This DC offset is removed in the receive path. The generation and characteristics of the DC offset will depend on the optical components and is therefore vendor discretionary. An example implementation of the addition of the DC offset to the modulated signal is shown in Annex A. + +#### 8.1.4.1 Subcarrier spacing and indexing + +See clause 7.1.4.1 of [ITU-T G.9960]. + +#### 8.1.4.2 Tone mapper + +See clause 7.1.4.2 of [ITU-T G.9960]. + +#### 8.1.4.3 Constellation encoder + +See clause 7.1.4.3 of [ITU-T G.9960]. + +#### 8.1.4.4 OFDM modulator + +The OFDM modulator consists of the following major parts: IDFT, cyclic extension, windowing, overlap and add and frequency up-shift. The incoming signal to the modulator at the $l$ th OFDM + +symbol in the present frame for a single subcarrier, with index $i$ , is the complex value $Z_{i,l}$ generated by the constellation encoder as described in clause 8.1.4.3 (for symbols of the header and the payload) or by preamble generator as described in clause 7.1.4.5.3 of [ITU-T G.9960] (for symbols of the preamble). Time-domain samples generated by the IDFT, after adding the cyclic prefix and windowing, are frequency up-shifted by $F_{US}$ . The functional diagram of the OFDM modulator is presented in Figure 8-2. + +![Functional model of the ITU-T G.9960-based OFDM modulator. The diagram shows a block diagram of the modulator. The input Z_{i,l} enters an IDFT block. The output of the IDFT block is X_{n,l}. This is followed by a 'Cyclic prefix N_{Cp}' block, which outputs V_{n,l}. This is followed by a 'Windowing, overlap and add' block, which outputs U_n. This is followed by a 'Frequency up-shift' block, which outputs S_{out}. The 'Frequency up-shift' block also receives an input F_{US}. The output S_{out} enters a 'DC-offset' block, which outputs the final signal s_n. The entire process from IDFT to Frequency up-shift is labeled 'OFDM modulator'. The diagram is labeled G.9991(19)_F8-2.](ed48e24e36ea0501953177401c900f86_img.jpg) + +Functional model of the ITU-T G.9960-based OFDM modulator. The diagram shows a block diagram of the modulator. The input Z\_{i,l} enters an IDFT block. The output of the IDFT block is X\_{n,l}. This is followed by a 'Cyclic prefix N\_{Cp}' block, which outputs V\_{n,l}. This is followed by a 'Windowing, overlap and add' block, which outputs U\_n. This is followed by a 'Frequency up-shift' block, which outputs S\_{out}. The 'Frequency up-shift' block also receives an input F\_{US}. The output S\_{out} enters a 'DC-offset' block, which outputs the final signal s\_n. The entire process from IDFT to Frequency up-shift is labeled 'OFDM modulator'. The diagram is labeled G.9991(19)\_F8-2. + +**Figure 8-2 – Functional model of the ITU-T G.9960-based OFDM modulator** + +An amplitude constant (DC offset) signal is added to the modulated signal in order to work within the LED operating range. + +The presented functional diagram and other figures presented in this clause do not imply any specific implementation. All aspects of signal processing used in the modulator shall comply with the equations and textual descriptions. + +##### 8.1.4.4.1 IDFT + +See clause 7.1.4.4.1 of [ITU-T G.9960]. + +##### 8.1.4.4.2 Cyclic extension + +See clause 7.1.4.4.2 of [ITU-T G.9960]. + +##### 8.1.4.4.3 Symbol timing + +See clause 7.1.4.4.3 of [ITU-T G.9960]. + +##### 8.1.4.4.4 Windowing, overlap and add + +See clause 7.1.4.4.4 of [ITU-T G.9960]. + +##### 8.1.4.4.5 Frequency up-shift + +The frequency up-shift offsets the spectrum of the transmit signal shifting it by $F_{US}$ . The value of $F_{US}$ shall be a multiple of the subcarrier frequency $F_{SC}$ : + +$$F_{US} = m * F_{SC}, \text{ where } m \text{ is an integer and } N/2 \leq m.$$ + +The valid values of $m$ are dependent on the source of light used and can be calculated from the values given in clause 8.2. + +The real and imaginary components of the signal after frequency up-shift (reference point $s_n$ in Figure 8-2) shall be as follows: + +$$s_n = u_{n/p} \times \exp\left(j \frac{2\pi mn}{Np}\right) = \text{Re}(s_n) + j \text{Im}(s_n) \quad \text{for } n = 0 \text{ to } [M(M_F - 1) + N_W(M_F - 1)] \times p - 1;$$ + +$$\text{Re}(s_n) = \text{Re}(u_{n/p}) \cos\left(\frac{2\pi mn}{Np}\right) - \text{Im}(u_{n/p}) \sin\left(\frac{2\pi mn}{Np}\right)$$ + +$$\text{Im}(s_n) = \text{Re}(u_{n/p}) \sin\left(\frac{2\pi mn}{Np}\right) + \text{Im}(u_{n/p}) \cos\left(\frac{2\pi mn}{Np}\right)$$ + +where $u_{n/p}$ is $u_n$ after interpolation with factor $p$ . The interpolation factor $p$ is vendor discretionary and shall be equal to or higher than 2. + +NOTE 1 – The minimum value of $p$ sufficient to avoid distortions depends on the ratio between the up-shift frequency $F_{US}$ and the bandwidth of the transmit signal $BW = N^*F_{sc}$ . It is assumed that an appropriate low-pass filter is included to reduce imaging. + +NOTE 2 – The phase of the up-shift should be initialized to zero at the first sample of the preamble and be advanced by $\frac{2\pi m}{Np}$ per each sample (after interpolation). + +##### 8.1.4.4.6 Output signal + +The output signal of the modulator shall be the real component of $s_n$ : + +$$S_{out} = \text{Re}(s_n).$$ + +##### 8.1.4.4.7 Improved supported dimming range + +If a wider range for dimming is supported, the following shall be performed together: + +- In the runtime BAT, the odd-index subcarriers shall be used for bit-loading and the number of loaded bits on every even-indexed subcarrier shall be set to zero. +- The values of the input to the IDFT (i.e., $Z_{i,l}$ ) for all even-indexed subcarriers shall be set to zero. + +#### 8.1.4.5 Preamble, INUSE, PR, NACK and IDPS signals + +See clause 7.1.4.5 of [ITU-T G.9960]. + +#### 8.1.4.6 PMD control parameters + +See clause 7.1.4.6 of [ITU-T G.9960]. + +#### 8.1.4.7 Symbol boost + +This Recommendation supports symbol boost as specified in clause 7.1.4.7 of [ITU-T G.9960]. + +### 8.1.5 Transmit PSD mask + +See clause 7.1.5 of [ITU-T G.9960]. + +### 8.1.6 Electrical specifications + +See clause 7.1.6 of [ITU-T G.9960]. + +## 8.2 Medium dependent specification + +### 8.2.1 Physical layer specification + +#### 8.2.1.1 Control parameters + +Table 8-12 shows the valid OFDM control parameters for various bandplans defined in VLC. + +**Table 8-12 – OFDM control parameters for VLC** + +| Domain type | VLC
(Note 2) | | | +|-----------------------------------|---------------------------------------------------------------|----------------------------------------------------------------|----------------------------------------------------------------| +| Bandplan name | 50 MHz
(Note 3) | 100 MHz
(Note 4) | 200 MHz
(Note 5) | +| Parameter | | | | +| $N$ | 256 | 512 | 1024 | +| $F_{SC}$ | 195.3125 kHz | 195.3125 kHz | 195.3125 kHz | +| $N_{GI}$ | $N/32 \times k$ for $k = 1, \dots, 8$ samples @ 50 Msamples/s | $N/32 \times k$ for $k = 1, \dots, 8$ samples @ 100 Msamples/s | $N/32 \times k$ for $k = 1, \dots, 8$ samples @ 200 Msamples/s | +| $N_{GI-HD}$ | $N/4 = 64$ samples @ 50 Msamples/s | $N/4 = 128$ samples @ 100 Msamples/s | $N/4 = 256$ samples @ 200 Msamples/s | +| $N_{GI-DF}$ | $N/4 = 64$ samples @ 50 Msamples/s | $N/4 = 128$ samples @ 100 Msamples/s | $N/4 = 256$ samples @ 200 Msamples/s | +| $\beta$ | $N/32 = 8$ samples @ 50 Msamples/s | $N/32 = 16$ samples @ 100 Msamples/s | $N/32 = 32$ samples @ 200 Msamples/s | +| $F_{US}$ | 25 MHz | 50 MHz | 100 MHz | +| $F_{UC}$ | 0 | 0 | 0 | +| Subcarrier indexing rule (Note 1) | Rule #1 | Rule #1 | Rule #1 | + +NOTE 1 – See clause 7.1.4.1 of [ITU-T G.9960] for more details on subcarrier indexing rules. +NOTE 2 – The 50 MHz, 100 MHz and 200 MHz bandplans may be used by nodes operating in the same domain. +NOTE 3 – The range of subcarrier frequencies is between 0 and 50 MHz. +NOTE 4 – The range of subcarrier frequencies is between 0 and 100 MHz. +NOTE 5 – The range of subcarrier frequencies is between 0 and 200 MHz. + +#### 8.2.1.2 Preamble, PR signal and INUSE signal + +##### 8.2.1.2.1 Preamble structure + +Table 8-13 illustrates the preamble structure for VLC. + +**Table 8-13 – Preamble structure for transmission over VLC** + +| | 1st section | 2nd section | 3rd section | +|--------------------------------------------|-------------|-------------|-------------| +| Number of symbols ( $N_i$ ) | 10 | 4 | 2.5 | +| Subcarrier spacing ( $k_i \times F_{SC}$ ) | $k_i = 4$ | $k_i = 4$ | $k_i = 1$ | + +##### 8.2.1.2.2 INUSE, PR and NACK signal generation parameters for VLC + +Table 8-14 illustrates the INUSE, PR and NACK signal generation parameters for VLC. + +**Table 8-14 – INUSE, PR and NACK signal generation parameters for VLC** + +| Parameter | Value | +|--------------------------------------------|-------| +| Number of symbols ( $N_{PRS}$ ) | 9 | +| Subcarrier spacing ( $k_i \times F_{SC}$ ) | 4 | + +##### 8.2.1.2.3 Modulation of the preamble for VLC + +When using a "default" seed, the constellation scrambler LFSR generator (see clause 7.1.4.3.3 of [ITU-T G.9960]) shall be initialized at the beginning of each one of the used preamble sections to a seed that is section dependent, as defined in Table 8-15. + +When using a "domain-specific" seed, the constellation scrambler LFSR generator (see clause 7.1.4.3.3 of [ITU-T G.9960]) shall be initialized at the beginning of each one of the used preamble sections to a set of seeds defined by the DM in the DM\_Defined\_Seed field of the additional domain information subfield (see clause 8.8.5.15 of [ITU-T G.9961]). + +**Table 8-15 – Default constellation scrambler initialization seed values +for the preamble, for VLC** + +| Medium | 1st section | 3rd section | +|---------------|--------------------|--------------------| +| VLC | 16E6 16 | 1105 16 | + +Domain-specific constellation scrambler initialization seed values for the preamble for VLC are for further study. + +##### **8.2.1.2.4 Modulation of the INUSE, PR and NACK signals for VLC** + +The constellation scrambler LFSR generator (see clause 7.1.4.3.3 of [ITU-T G.9960]) shall be initialized at the beginning of the INUSE, PR and NACK signals to the same seed used for the 1st preamble section, as defined in Table 8-15. + +#### **8.2.1.3 PSD mask specifications** + +No PSD mask is defined by this Recommendation since the power required to drive the emitting device may differ between implementations. + +#### **8.2.1.4 Permanently masked subcarriers** + +For baseband transmissions, subcarriers 0-10 (inclusive) shall be permanently masked over VLC. They shall not be used for transmission (neither data nor any auxiliary information). + +#### **8.2.1.5 Coexistence on VLC** + +This clause is for further study. + +### **8.2.2 Transmitter EVM requirements** + +No EVM requirements are specified for this Recommendation. + +### **8.2.3 Termination impedance** + +No termination impedance requirements are specified for this Recommendation. + +### **8.2.4 Total transmit power** + +No total transmit power is defined by this Recommendation since the power required to drive the emitting device may differ between implementations. + +### **8.2.5 Receiver input impedance** + +No receiver input impedance is specified for this Recommendation. + +### **8.2.6 Longitudinal conversion loss** + +No longitudinal conversion loss is specified for this Recommendation. + +# 9 Physical layer specification II (ACO-OFDM) + +## 9.1 Medium independent specification + +### 9.1.1 Functional model of the PHY + +The functional model of the PHY is presented in Figure 9-1. The PMI and MDI are, respectively, two demarcation reference points between the PHY and MAC and between the PHY and the transmission medium. Internal reference points $\delta$ and $\alpha$ show separation between the PMD and PMA, and between the PCS and PMA, respectively. + +![Functional model of the PHY diagram showing the flow of data from MPDU in to MPDU out through PCS, PMA, and PMD sublayers, with control data from PHY management.](13fde41de77bf026013a0b81684d1fc9_img.jpg) + +``` + +graph TD + subgraph PHY_Management [PHY management] + PM_CTRL[PHY management] + end + + MPDU_IN[MPDU in] --> PCS + PCS --> MPDU_OUT[MPDU out] + + subgraph PCS_Block [Physical coding sublayer - PCS] + PCS[generation of PHY-frame, mapping MAC frames into the PHY-frame] + end + + PCS <--> |PCS control data| PM_CTRL + + PCS -- TX PHY frame --> PMA + PMA -- RX PHY frame --> PCS + + subgraph PMA_Block [Physical media attachment - PMA] + PMA[scrambling, FEC, segmentation to OFDM symbols, padding] + end + + PMA <--> |PMA control data| PM_CTRL + + PMA -- TX symbol frames --> PMD + PMD -- RX symbol frames --> PMA + + subgraph PMD_Block [Physical medium dependent - PMD] + PMD[subcarrier mapping, constellation encoding, ACO-OFDM modulation, preamble insertion] + end + + PMD <--> |PMD control data| PM_CTRL + + PMD <--> MDI_Line[MDI] + MDI_Line <--> LEDs[LEDs] + + %% Reference Points + PMI_Ref[PMI] -.- PCS_Block + Alpha_Ref[alpha-reference point] -.- PMA_Block + Delta_Ref[delta-reference point] -.- PMD_Block + MDI_Ref[MDI] -.- MDI_Line + +``` + +The diagram illustrates the functional model of the PHY. It shows three main sublayers: Physical coding sublayer (PCS), Physical media attachment (PMA), and Physical medium dependent (PMD). Data flow is as follows: MPDU in enters the PCS from the MAC via the PMI. The PCS generates a PHY-frame and maps MAC frames into it. A TX PHY frame is sent from the PCS to the PMA at the $\alpha$ -reference point. The PMA performs scrambling, FEC, segmentation to OFDM symbols, and padding. TX symbol frames are sent from the PMA to the PMD at the $\delta$ -reference point. The PMD performs subcarrier mapping, constellation encoding, ACO-OFDM modulation, and preamble insertion. The output is transmitted over the medium via the MDI. RX symbol frames are received from the medium at the MDI and passed to the PMD. RX PHY frames are received from the PMD at the $\delta$ -reference point and passed to the PMA. RX PHY frames are received from the PMA at the $\alpha$ -reference point and passed to the PCS. The PCS generates the MPDU out to the MAC. Control data from PHY management is sent to each sublayer: PCS control data to the PCS, PMA control data to the PMA, and PMD control data to the PMD. LEDs are shown at the MDI interface. The diagram is labeled G.9991(19)\_F9-1. + +Functional model of the PHY diagram showing the flow of data from MPDU in to MPDU out through PCS, PMA, and PMD sublayers, with control data from PHY management. + +Figure 9-1 – Functional model of the PHY + +In the transmit direction, data enters the PHY from the MAC via the PMI in blocks of bytes called MAC protocol data units (MPDUs). The incoming MPDU is mapped into a PHY frame in the PCS, scrambled and encoded in the PMA, modulated in the PMD and transmitted over the medium using ACO-OFDM modulation with the relevant parameters specified in clause 9.1.4. In the PMD, a preamble is added to assist synchronization and channel estimation in the receiver. + +In the receive direction, frames entering from the medium via the MDI are demodulated and decoded. The recovered MPDUs are forwarded to the MAC via the PMI. The recovered PHY-frame headers are processed in the PHY to extract the relevant frame parameters specified in clause 9.1.2.3. + +### 9.1.2 Physical coding sublayer (PCS) + +The functional model of the PCS is presented in Figure 9-2. It is intended to describe in more detail the PCS functional block presented in Figure 9-1. + +![Figure 9-2 – Functional model of PCS. A block diagram showing the transmit and receive paths of the PCS. The transmit path starts with 'MPDU in' entering an 'MPDU mapper', which feeds into a 'MUX (TDM)'. A 'Header generation' block also feeds into the 'MUX (TDM)'. The output is 'TX PHY frame'. The receive path starts with 'RX PHY frame' entering 'Header processing', which feeds into an 'MPDU de-mapper' and outputs 'MPDU out'. 'Header processing' and 'Header generation' exchange 'PCS control data' with a 'PHY management' entity on the right. An 'α-reference point' dashed line separates the PCS from the lower layers.](0b7849dae424b0dd33e6386d2384643a_img.jpg) + +``` + +graph TD + subgraph PCS + MPDU_in[MPDU in] --> MPDU_mapper[MPDU mapper] + MPDU_mapper --> MUX[MUX TDM] + Header_gen[Header generation] --> MUX + MUX --> TX_PHY[TX PHY frame] + + RX_PHY[RX PHY frame] --> Header_proc[Header processing] + Header_proc --> MPDU_demapper[MPDU de-mapper] + MPDU_demapper --> MPDU_out[MPDU out] + end + + PHY_mgmt[PHY management] -- PCS control data --> Header_gen + Header_proc -- PCS control data --> PHY_mgmt + + PMI_line[--- PMI ---] -.-> MPDU_mapper + PMI_line -.-> MPDU_demapper + Alpha_line[--- α-reference point ---] -.-> TX_PHY + Alpha_line -.-> RX_PHY + +``` + +Figure 9-2 – Functional model of PCS. A block diagram showing the transmit and receive paths of the PCS. The transmit path starts with 'MPDU in' entering an 'MPDU mapper', which feeds into a 'MUX (TDM)'. A 'Header generation' block also feeds into the 'MUX (TDM)'. The output is 'TX PHY frame'. The receive path starts with 'RX PHY frame' entering 'Header processing', which feeds into an 'MPDU de-mapper' and outputs 'MPDU out'. 'Header processing' and 'Header generation' exchange 'PCS control data' with a 'PHY management' entity on the right. An 'α-reference point' dashed line separates the PCS from the lower layers. + +**Figure 9-2 – Functional model of PCS** + +In the transmit direction, the incoming MPDU is mapped into a payload field of a PHY frame (clause 9.1.2.1) as described in clause 9.1.2.2. The PHY-frame header (clause 9.1.2.3) is then added to form a TX PHY frame. The TX PHY frame is passed across the $\alpha$ -reference point for further processing in the PMA. + +In the receive direction, the decoded header and PHY-frame payload are processed and originally transmitted MPDUs are recovered from the payloads of received PHY frames and submitted to the PMI. Relevant control information conveyed in the PHY-frame header is processed and submitted to the PHY management entity. + +#### 9.1.2.1 PHY frame + +See clause 8.1.2.1. + +#### 9.1.2.2 MPDU mapping + +See clause 8.1.2.2. + +#### 9.1.2.3 PHY-frame header + +See clause 8.1.2.3. + +### 9.1.3 Physical medium attachment (PMA) sublayer + +See clause 8.1.3. + +### 9.1.4 Physical medium dependent (PMD) sublayer + +The functional model of the PMD is presented in Figure 8-1. In the transmit direction, the tone mapper divides the incoming symbol frames including header and payload into groups of bits and associates each group of bits with a specific subcarrier onto which this group shall be loaded, as specified in clause 9.1.4.2. The constellation encoder converts each incoming group of bits into a complex number that represents the constellation point for this subcarrier. The constellation mapping process is described in clause 9.1.4.3. The unloaded supported subcarriers are modulated by a pseudorandom bit sequence generated as described in clause 9.1.4.2. + +The asymmetrically clipped optical OFDM (ACO-OFDM) modulator (clause 9.1.4.4) converts the stream of the $N$ complex numbers with Hermitian conjugate symmetry at its input into the stream of $N$ real valued time-domain samples. After adding the preamble, the resultant signal is clipped at the zero level and only the positive part is used to transmit by the LED. Parameters of the preamble (clause 9.1.4.5) are determined by the PHY management and depend on the type of the transmitted PHY frame. + +Frames are output on to the LED with inter-frame gaps. + +In the receive direction, the frames incoming from the photodetector are demodulated and decoded. The recovered symbol frames are transferred to the PMA via the $\delta$ -reference point. The preamble is processed and preamble data are passed to the PHY management entity. + +NOTE – An amplitude constant (DC offset) signal may be added to the modulated signal to ensure the system working within the LED operating range. This DC offset is removed in the receive path. + +#### 9.1.4.1 Subcarrier spacing and indexing + +The subcarrier spacing $F_{sc}$ is the frequency spacing between any two adjacent subcarriers. Valid values of subcarrier spacing are presented in clause 9.1.4.6 (PMD control parameters). + +In an OFDM-based VLC system only the first half subcarriers are used for data transmission and the other half are used to impose Hermitian symmetry to ensure that the IDFT outputs are real valued time-domain samples (see clause 9.1.4.4). + +The physical index $i$ corresponds to the order of subcarriers in ascending frequency. The index $i$ goes from 0 to $N - 1$ . + +Table 9-1 lists three modes of subcarrier usage. One of the them shall be used. + +**Table 9-1 – Three modes of subcarrier usage** + +| Mode | Subcarrier usage | +|------|-----------------------------------------------------------------------------------------------------------------------------------| +| 1 | The $i$ th subcarrier is active if $i$ is odd and is inactive if $i$ is even. | +| 2 | The $i$ th subcarrier is active if $i \equiv 1, 2, \text{ or } 3 \pmod{4}$ and is inactive if $i \equiv 0 \pmod{4}$ . | +| 3 | The $i$ th subcarrier is active if $i \equiv 1, 2, 3, 4, 5, 6, \text{ or } 7 \pmod{8}$ and is inactive if $i \equiv 0 \pmod{8}$ . | + +The logical index $j$ indicates the order in which data is loaded on subcarriers. + +The indexing rules that relate the physical index and the logical index are defined: + +Mode 1: The index $j$ goes from 0 to $N/4 - 1$ and + +$$i = 2j + 1$$ + +Mode 2: The index $j$ goes from 0 to $3N/8 - 1$ and + +$$i = j + \left\lfloor \frac{j}{3} \right\rfloor + 1$$ + +Mode 3: The index $j$ goes from 0 to $7N/16 - 1$ and + +$$i = j + \left\lfloor \frac{j}{7} \right\rfloor + 1$$ + +Throughout this Recommendation, the term "subcarrier" refers to the valid subcarrier, unless otherwise noted. The term "subcarrier index" refers to the physical index, unless otherwise noted. + +Not all odd subcarriers may always be used for data transmission; some of them have to be switched off in special circumstances. Others may be only used with reduced power. The latter functions are performed by subcarrier masking and gain scaling (see clauses 5.1 and 5.2 of [ITU-T G.9964]). + +#### 9.1.4.2 Tone mapper + +The tone mapper divides the incoming symbol frames of the header and payload into groups of bits (according to the BATs and subcarrier grouping being used) and associates each group of bits with specific subcarriers onto which these groups shall be loaded. This information along with subcarrier-specific gain scaling values as described in clause 9.1.4.3 are passed to the constellation encoder. + +##### 9.1.4.2.1 Summary of subcarrier types + +For the purpose of tone mapping, the following types of valid subcarriers are defined. + +- 1) Masked subcarriers (MSCs) are those on which transmission is not allowed, i.e., the gain on this subcarrier shall be set to zero. Two types of MSC are defined: + - Permanently masked subcarriers (PMSCs) – those that are never allowed for transmission. The list of PMSCs includes all even subcarriers and the PMSC mask, which is defined in clause 9.2. Data bits are never mapped on PMSCs. + - Regionally masked subcarriers (RMSMs) – those that are not allowed for data transmission in some regions, while may be allowed in other regions. The list of RMSMs forms an RMSM mask, which consists of the subcarriers corresponding to subcarrier masks defined in the SM descriptor and masked amateur radio bands defined in the amateur radio band descriptor. The number of RMSMs, $\#RMSM = \#MSC - \#PMSC$ . In this Recommendation, the set of RMSMs shall be empty. +- 2) Supported subcarriers (SSCs) are those on which transmission is allowed under restrictions of the relevant PSD mask. The number of SSCs, $\#SSC = N/2 - 1 - \#MSC$ . The following types of SSC are defined: + - Active subcarriers (ASCs) – those that have loaded bits ( $b \geq 1$ ) for data transmission. ASCs are subject to constellation point mapping, constellation scaling and constellation scrambling as described in clause 9.1.4.3. Data bits shall be mapped on ASCs as described in clause 9.1.4.2.2. + - Inactive subcarriers (ISCs) – those that do not have any data bits loaded (e.g., because signal to noise ratio (SNR) is low). The number of ISCs, $\#ISC = \#SSC - \#ASC$ . ISCs can be used for measurement purposes or other auxiliary purposes. ISCs are subject to transmit power shaping. The signals transmitted on ISC are defined in clause 9.1.4.2.6. + +##### 9.1.4.2.2 Bit allocation tables (BATs) + +See clause 7.1.4.2.2 of [ITU-T G.9960]. + +##### 9.1.4.2.3 Transmitter-determined and receiver-determined mapping + +See clause 7.1.4.2.3 of [ITU-T G.9960]. + +##### 9.1.4.2.4 Special mappings + +See clause 7.1.4.2.4 of [ITU-T G.9960]. + +##### 9.1.4.2.5 BAT with subcarrier grouping + +See clause 7.1.4.2.5 of [ITU-T G.9960]. + +##### 9.1.4.2.6 Modulation of unloaded supported subcarriers + +See clause 7.1.4.2.6 of [ITU-T G.9960]. + +##### 9.1.4.2.7 Subcarrier index modulation + +In subcarrier index modulation (SIM), the positions of used subcarriers in the frequency domain are utilized to transmit extra bits without additional power. Assuming the same bit loading over all subcarriers, given a dimming level, the average signal power per subcarrier can be determined. The maximum number of supported subcarriers (denoted by $n_a$ ) is determined using the signal power for a given bit error rate (BER) and a given constellation size. + +$$n_a = \min \left\{ \left\lfloor \frac{r^2 * n}{2N_0\gamma} \right\rfloor, n \right\}$$ + +where $r$ denotes the RMS of total signal, $N_0$ denotes the noise power and the threshold $\gamma$ is determined by a particular BER and other modulation parameters. If $M$ -ary QAM modulation is adopted, the relationship between BER and SNR $\Gamma_{b(elec)}$ can be expressed as + +$$BER = \frac{4(\sqrt{M} - 1)}{\sqrt{M} \log_2(M)} Q\left(\sqrt{\frac{3 \log_2(M)}{M - 1} \Gamma_{b(elec)}}\right) + \frac{4(\sqrt{M} - 2)}{\sqrt{M} \log_2(M)} Q\left(3\sqrt{\frac{3 \log_2(M)}{M - 1} \Gamma_{b(elec)}}\right)$$ + +Then the threshold $\gamma$ is given by + +$$\gamma = \Gamma_{b(elec)} * \log_2(M)$$ + +- If the total number of subcarriers (denoted by $n$ ) is no greater than the maximum number of supported subcarriers $n_a$ , then the OFDM with all supported subcarriers shall be used. +- The equivalent number of subcarriers when SIM is used (denoted by $n_e$ ) is + +$$n_e = n_t + \frac{b_t}{\log_2(M)}$$ + +where $b_t$ denotes the extra transmission bits drawn from index modulation and the number of active subcarriers $n_t$ can be expressed as + +$$n_t = \min\left\{\left\lfloor \frac{r^2 * n}{2N_0\gamma_t} \right\rfloor, n\right\}$$ + +- If $n_e$ is smaller than the maximum number of supported subcarriers $n_a$ , then the OFDM with $n_a$ supported subcarriers shall be used without SIM. The values of the input to the IDFT (i.e., $Z_{i,l}$ ) for the unused subcarriers shall be set to zero. +- If $n_e$ is greater than $n_a$ , then the OFDM with SIM shall be used. The values of the input to the IDFT (i.e., $Z_{i,l}$ ) for the unused subcarriers shall be set to zero. + +The number of supported subcarriers shall be communicated from the transmitter to the receiver. + +SIM with variable bit loading over all subcarriers is for further study. + +#### 9.1.4.3 Constellation encoder + +See clause 8.1.4.3. + +#### 9.1.4.4 OFDM modulator + +The OFDM modulator consists of the following major parts: IDFT, clipping, cyclic extension, windowing, overlap and add. The incoming signal to the modulator at the $l$ th OFDM symbol in the present frame for a single subcarrier, with index $i$ , is the complex value $Z_{i,l}$ generated by the constellation encoder as described in clause 9.1.4.3 (for symbols of the header and the payload) or by preamble generator as described in clause 7.1.4.5.3 of [ITU-T G.9960] (for symbols of the preamble). Hermitian symmetry shall be applied to $Z_{i,l}$ as follows to ensure the IDFT outputs are real valued time-domain samples: + +$$Z_{0,l} = Z_{\frac{N}{2},l} = 0$$ + +$$Z_{i,l} = Z_{N-i,l}^* \quad \text{for } i = 1, 2, \dots, \frac{N}{2} - 1$$ + +where $*$ denotes complex conjugation. After time-domain samples generated by the IDFT, the real part of the resultant signal is clipped at the zero level. Then the cyclic prefix is added and windowing, overlap and add are processed. The functional diagram of the OFDM modulator is presented in Figure 9-3. + +![Functional model of the ACO-OFDM modulator block diagram. The input Z_{n,l} enters a block labeled 'OFDM modulator'. Inside, the signal passes through four stages: 'IDFT', 'Clipping', 'Cyclic prefix N_{CP}', and 'Windowing, overlap and add'. The output of the 'IDFT' stage is labeled X_{n,l}. The output of the 'Clipping' stage is labeled P_{n,l}. The output of the 'Cyclic prefix' stage is labeled V_n. The output of the 'Windowing, overlap and add' stage is labeled S_n. The final output of the 'OFDM modulator' block is S_{out}. A reference label G.9991(19)_F9-3 is at the bottom right.](0a42e05c07941450f34e4f7117725834_img.jpg) + +Functional model of the ACO-OFDM modulator block diagram. The input Z\_{n,l} enters a block labeled 'OFDM modulator'. Inside, the signal passes through four stages: 'IDFT', 'Clipping', 'Cyclic prefix N\_{CP}', and 'Windowing, overlap and add'. The output of the 'IDFT' stage is labeled X\_{n,l}. The output of the 'Clipping' stage is labeled P\_{n,l}. The output of the 'Cyclic prefix' stage is labeled V\_n. The output of the 'Windowing, overlap and add' stage is labeled S\_n. The final output of the 'OFDM modulator' block is S\_{out}. A reference label G.9991(19)\_F9-3 is at the bottom right. + +**Figure 9-3 – Functional model of the ACO-OFDM modulator** + +The presented functional diagram and other figures presented in this clause do not imply any specific implementation. All aspects of signal processing used in the modulator shall comply with the equations and textual descriptions. + +##### 9.1.4.4.1 IDFT + +See clause 8.1.4.4.1. + +##### 9.1.4.4.2 Clipping + +Because of Hermitian symmetry, the result of IDFT $x_{n,l}$ is a real valued sequence theoretically. The transmitted signal should be clipped at the zero level and only the positive part of $x_{n,l}$ is used for transmission. The clipping can be expressed as in the follow equation: + +$$P_{n,l} = (x_{n,l} + |x_{n,l}|)/2$$ + +Where $|\cdot|$ denotes the absolute value. To guarantee the real value, only the real parts of $x_{n,l}$ can be retained before clipping. + +##### 9.1.4.4.3 Cyclic extension + +See clause 8.1.4.4.2. + +##### 9.1.4.4.4 Symbol timing + +See clause 8.1.4.4.3. + +##### 9.1.4.4.5 Windowing, overlap and add + +See clause 8.1.4.4.4. + +##### 9.1.4.4.6 Output signal + +The output signal of the modulator shall be the real component of $s_n$ : + +$$S_{\text{out-BB}} = \text{Re}(S_n).$$ + +#### 9.1.4.5 Preamble, INUSE, PR, NACK and IDPS signals + +See clause 8.1.4.5. + +#### 9.1.4.6 PMD control parameters + +See clause 8.1.4.6. + +#### 9.1.4.7 Symbol boost + +See clause 8.1.4.7. + +### 9.1.5 Transmit PSD mask + +See clause 8.1.5. + +### 9.1.6 Electrical specifications + +See clause 8.1.6. + +## 9.2 Medium dependent specification + +See clause 8.2. + +# 10 Data link layer specification + +## 10.1 Functional model and frame formats + +### 10.1.1 Functional model of the data link layer (DLL) + +The functional model of the DLL is presented in Figure 10-1. The A-interface is the demarcation point between the application entity (AE) and the data link layer (DLL); the physical medium independent (PMI) interface is the demarcation point between the DLL and the physical (PHY) layer. Internal reference points x1 and x2 show logical separation between the application protocol convergence (APC) and LLC and between the LLC and MAC, respectively. + +![Functional model of the DLL diagram showing layers APC, LLC, and MAC with their interfaces and management entity connections.](a3083eec2a883ee8327b3c24174df6a9_img.jpg) + +The diagram illustrates the functional model of the Data Link Layer (DLL). It consists of three main layers stacked vertically, separated by dashed horizontal lines representing interfaces and reference points. At the top, the 'A-interface' is shown. Below it is the 'Application protocol convergence (APC)' layer, which handles 'ADP in' and 'ADP out' data. It also interacts with a 'DLL management entity' on the right, exchanging 'AAT data, classification data, high-level management messages'. Below the APC layer is the 'x1 reference point'. The next layer is the 'Logical link control (LLC)' layer, which handles 'APDU' data. It also interacts with the 'DLL management entity', exchanging 'LCDU data' and 'QoS parameters'. Below the LLC layer is the 'x2 reference point'. The bottom layer is the 'Media access control (MAC)' layer, which handles 'LPDU' data. It interacts with the 'DLL management entity', exchanging 'Media access control parameters'. At the very bottom, the 'PMI' (Physical Medium Independent) interface is shown, with 'MPDU' data entering and leaving the MAC layer. The diagram is labeled 'G.9991(19)\_F10-1' in the bottom right corner. + +Functional model of the DLL diagram showing layers APC, LLC, and MAC with their interfaces and management entity connections. + +Figure 10-1 – Functional model of the DLL + +In the transmit direction, application data primitive (ADP) sets enter the DLL from the AE across the A-interface. Every incoming ADP set meets the format defined by the particular application protocol; for an Ethernet type AE, the ADP set has one of the standard Ethernet formats, as presented in Annex A of [ITU-T G.9961] (Ethernet APC). Each incoming ADP set is converted by the APC into APC protocol data units (APDUs), which include all parts of the ADP set intended for communication to the destination node(s). The APC also identifies ADP classification primitives (e.g., priority tags), which can be used by the LLC to support QoS requirements assigned to the service delivered by the ADP. Furthermore, the APC is responsible for establishing flows of APDUs between peer APCs and assigning one or more queues for these flows according to the classification information associated with each APDU. The number of queues may depend on the profile of the device; for the Ethernet + +APC, mapping of user priorities to the same destination into priority queues (traffic classes) shall follow Table III.1 of [ITU-T G.9960]. + +The APDUs are transferred to the LLC across the x1 reference point, which is both application independent and medium independent. In addition, LLC receives management data primitives from the DLL management entity intended for LLC control frames, which are mapped into link control data units (LCDUs). The LLC is responsible for establishing flows of LCDU (control frames) between peer LLCs. + +In the LLC, the incoming APDU and LCDU are converted into LLC frames and may be encrypted using assigned encryption keys (see clause 11). LLC frames are subject to concatenation and segmentation, as described in clause 10.1.3.2. Segments are transformed into LLC protocol data units (LPDUs) by adding an LPDU header (LPH) and CRC. LPDUs are then passed to the MAC across the x2 reference point. The LLC is also responsible for retransmission and relay operations. + +The MAC is responsible for concatenating LPDUs into MAC protocol data units (MPDUs) and then conveying these MPDUs to the PHY in the order determined by the LLC (scheduling, using number of transmission queues) and applying medium access rules established in the domain. + +In the receive direction, MPDUs from the PHY enter the MAC across the PMI together with associated PHY frame error information. The MAC disassembles the received MPDU into LPDUs, which are passed over the x2 reference point to the LLC. The LLC recovers the original APDUs and LCDUs from the LPDUs, performs decryption if required and conveys them to the APC and LLC management entity, respectively. In the APC ADPs are generated from the received APDUs and conveyed to the AE. + +The LLC is responsible for the decision regarding errored LPDUs. It decides whether to request retransmission of errored LPDUs (and generates the ACK response to assist retransmission), or to discard the errored LPDUs. + +The functionality of the APC, LLC and MAC is the same for all types of medium, although some of their functions and control parameters may be adjusted for efficient operation of the transceiver over particular media. Specific control parameters for APC, LLC and MAC are described in clause 10.3. + +NOTE – No assumptions should be made on the partitioning of APC, LLC and MAC in particular implementations; x1 and x2 are reference points and serve for the convenience of system definition. + +### **10.1.2 Application protocol convergence (APC)** + +The functional model of the APC is presented in Figure 10-2. It is intended to describe in more detail the APC functional block presented in Figure 10-1. + +![Functional model of APC diagram showing data flow from ADP in to TX APDU and RX APDU to ADP out, with various processing blocks like ADP-to-APDU converter, Flow mapper, Classifier, AAT, Shaping/smoothing buffer, and Dispatcher. It also shows management paths for local and remote in-band management and DLL management.](12c19090355e19922e23044633b9d1ea_img.jpg) + +The diagram illustrates the functional model of the APC (Adaptation Protocol Control). It shows the flow of data units (ADP and APDU) through various processing stages. On the left, 'ADP in' enters from the top, passing through an 'ADP-to-APDU converter' and then a 'Flow mapper'. The 'Flow mapper' receives 'Classification', 'Destination DEVICE\_ID', and 'Flow management data' from a 'Classifier' and 'AAT (local and remote)' block. The output of the 'Flow mapper' is 'TX APDU', which exits at the bottom. On the right, 'RX APDU' enters from the bottom, passing through a 'Dispatcher' and then a 'Shaping/smoothing buffer'. The output of the buffer is 'APDU-to-ADP converter', which produces 'ADP out' at the top. A 'DLL management' entity on the far right interacts with 'Local in-band management' and 'Remote in-band management' paths. The 'AAT (local and remote)' block sends 'AAT data' to the 'DLL management' entity, and the 'Classifier' sends 'QoS data'. The 'Shaping/smoothing buffer' receives 'Shaping control' from the 'DLL management' entity. Dashed lines represent the 'A-interface' (top) and 'x1 reference point' (bottom). + +Functional model of APC diagram showing data flow from ADP in to TX APDU and RX APDU to ADP out, with various processing blocks like ADP-to-APDU converter, Flow mapper, Classifier, AAT, Shaping/smoothing buffer, and Dispatcher. It also shows management paths for local and remote in-band management and DLL management. + +G.9991(19)\_F10-2 + +**Figure 10-2 – Functional model of APC** + +In the transmit direction, the incoming ADP is converted into an APDU as defined in Annex A of [ITU-T G.9961]. The flow mapper maps APDUs into flows, depending on their destination DEVICE\_ID, class of service and QoS support capabilities of the communicating nodes. Flows are established in the APC by DLL management after receiving relevant data units from the AE, or during admission to the network, or by high-level management requests coming across the A-interface, or upon request from another node (by means of flow establishment protocol messages coming across the x1 reference point). After mapping, each APDU, tagged with its FLOW\_ID or PRI-Q, is sent across the x1 reference point to the LLC. The order of outgoing APDUs at the x1-reference point associated with a particular DID and a particular user priority and within a particular service flow shall be the same as the order of arrival of the ADPs sourcing these APDUs. + +The data units of the in-band management messages arriving across the A-interface and addressed to the local node are directed to the DLL management entity ("Local in-band management", at the bottom of Figure 10-2). The in-band management messages generated by DLL management entity for the remote AE are converted to APDUs and sent across the x1 reference point ("Remote in-band management" at the top of Figure 10-2). + +In the receive direction, the incoming APDUs crossing the x1 reference point are converted back into the ADP data unit primitives of the relevant application protocol. A shaping (smoothing) buffer, controlled by DLL management entity, may be included for traffic shaping of the outgoing (i.e., in the direction of the AE) ADP data units. + +If addressed to the node, APDUs carrying in-band management messages from the remote AE are dispatched to the DLL management entity ("Remote in-band management" at the bottom of Figure 10-2). If addressed to the local AE, APDUs carrying in-band management messages from the + +remote AE are converted to a standard ADP and passed to A-interface. The in-band management messages (e.g., responses) generated by DLL management entity for the local AE are sent to the AE across the A-interface as standard sets of data unit primitives ("Local in-band management" at the top of Figure 10-2). + +The classification information embedded in the ADP is extracted from the incoming data units and may be used to set an appropriate type of traffic (flow) or to assign a user priority, or both, to convey the corresponding APDU through the network. Classification parameters are presented in Annex A of [ITU-T G.9961]. + +The local address association table (LAAT) contains in its first entry the MAC address of the node itself (i.e., REGID) and, in the rest of the table, the MAC addresses of the clients associated with the node. This data is collected from the incoming ADP data units; LAAT data is passed to the DLL management entity for network management purposes (see clause 10.4.3). + +The remote address association table (RAAT) stores MAC addresses of other nodes in the domain and their associated clients that were advertised on the network. + +The address association table (AAT) is formed by the aggregation of LAAT and RAAT. + +### 10.1.3 Logical link control (LLC) + +The functional model of the LLC is presented in Figure 10-3. It is intended to describe in more detail the LLC functional block presented in Figure 10-1. + +![Functional model of LLC diagram showing data flow from APDU in to TX LPDU and from RX LPDU to APDU out, with various processing blocks and control signals.](fd76efce549d3713543bb5ed9b023c2e_img.jpg) + +The diagram illustrates the functional model of the Logical Link Control (LLC) layer. It shows the flow of data units (APDUs) through various processing stages, with reference points x1 and x2. + +- Reference Points:** + - x1 reference point:** Located between the 'APDU in' input and the 'Generation of LCDU' block. + - x2 reference point:** Located between the 'ARQ buffer' and 'TX LPDU' output on the left, and the 'Detection and replacement of errored LPDUs' and 'RX LPDU' input on the right. +- Transmit Path (Left Side):** + - APDU in:** Input data unit. + - Encryption:** Processes the APDU. + - Assembling of LLC frame:** Adds LLC headers/footers. + - Concatenation and segmentation:** Prepares data for transmission. + - ARQ buffer:** Stores data for error recovery. + - TX LPDU:** Output data unit. + - Control Signals:** + - Generation of LCDU:** Receives 'TX LCDU data' from the DLL management entity and provides input to the 'Encryption' block. + - Relay control:** Receives 'Relayed LLC frame' from the 'Relay function' block and provides input to the 'Concatenation and segmentation' block. + - ARQ control:** Connects the 'ARQ buffer' to the 'Concatenation and segmentation' block. +- Receive Path (Right Side):** + - RX LPDU:** Input data unit. + - Detection and replacement of errored LPDUs:** Processes incoming LPDUs and sends 'ACK' back to the 'ARQ buffer'. + - De-segmentation:** Processes the data unit. + - Process LFH:** Checks the Link Frame Header against the 'AAT check' from the DLL management entity. + - Decryption:** Decrypts the data unit, receiving 'RX LCDU data' from the DLL management entity. + - APDU out:** Output data unit. + - Control Signals:** + - Relay function:** Receives 'LLC frame' from 'Process LFH' and sends 'Relayed LLC frame' to the 'Relay control' block. + - ACK info and control:** Connects the 'Detection and replacement of errored LPDUs' block to the 'DLL management' entity. +- DLL management:** A central entity providing management and control data to both the transmit and receive paths. + +Functional model of LLC diagram showing data flow from APDU in to TX LPDU and from RX LPDU to APDU out, with various processing blocks and control signals. + +G.9991(19)\_F10-3 + +Figure 10-3 – Functional model of LLC + +In the transmit direction, an LLC frame is formed from each incoming APDU crossing the x1 reference point, which may be encrypted using the encryption rules defined in clause 11. One or more LLC frames are concatenated and further divided into segments of equal size. Each segment is prepended by an LPDU header and appended with an LPDU CRC, forming an LPDU. + +The LLC management data to be conveyed is assembled into an LCDU. The format of the LCDU is universal for all types of media and is described in clause 10.1.3.4. The LCDU is further mapped into an MPDU as described in clause 10.1.4.1. + +LPDUs that are subject to automatic repeat request (ARQ) (need to be retransmitted) are extracted from the ARQ buffer and passed to the MAC to be assembled into the outgoing MPDU. To assist retransmission, the receive part of the LLC generates ACKs, which are also passed to the MAC (see clause 10.8). The number of LLC frames to be concatenated, the size of the segment and other MPDU formatting parameters are controlled by the LLC. The LPDUs are passed to the MAC across the x2 reference point. + +In the receive direction, the incoming MPDU is disassembled into LPDUs in the MAC and passed over the x2 reference point. The LLC verifies the LPDUs, requests replacements for any errored ones if so instructed and recovers LLC frames from the LPDUs. The recovered LLC frames are decrypted and passed to APC as APDUs. Recovered LCDUs are passed to the DLL management entity. + +The relay function extracts LLC frames that are subject to relaying and passes them to the transmit side, which concatenates them into the traffic to the next hop. The DLL management controls flow and priority settings for the relayed LLC frames. Relayed LLC frames shall not be decrypted. + +#### **10.1.3.1 LLC frame format** + +See clause 8.1.3.1 of [ITU-T G.9961]. + +#### **10.1.3.2 Generation of LPDUs** + +See clause 8.1.3.2 of [ITU-T G.9961]. + +#### **10.1.3.3 Generation of LPDUs for retransmission** + +See clause 8.1.3.3 of [ITU-T G.9961]. + +#### **10.1.3.4 LCDU frame format** + +See clause 8.1.3.4 of [ITU-T G.9961]. + +### **10.1.4 Medium access control (MAC)** + +The functional model of the MAC is presented in Figure 10-4. It is intended to describe in more detail the MAC functional block presented in Figure 10-1. + +![Functional model of MAC diagram showing the flow of data from LPDU in to LPDU out through MPDU assembly, scheduling, and disassembly, with control signals from DLL management and PHY primitives like CRS and PMI.](2580688a4de0a29692805cc6ba4822d7_img.jpg) + +The diagram illustrates the functional model of the MAC. At the top, 'LPDU in' enters from above and passes through an 'MPDU assembler'. Below this is a dashed line labeled 'x2 reference point'. The 'MPDU assembler' outputs to a 'Scheduler'. To the right, 'LPDU out' exits upwards from an 'MPDU disassembler', which also sits below the 'x2 reference point'. The 'Scheduler' outputs to 'TX MPDU' below another dashed line labeled 'PMI'. The 'Scheduler' also receives input from 'CRS' (Carrier Sense) and 'RX MPDU' (Receive MPDU). A vertical line labeled 'Media access control' connects the 'MPDU disassembler' and the 'Scheduler' to 'DLL management' at the top right. The diagram is labeled 'G.9991(19)\_F10-4' at the bottom right. + +Functional model of MAC diagram showing the flow of data from LPDU in to LPDU out through MPDU assembly, scheduling, and disassembly, with control signals from DLL management and PHY primitives like CRS and PMI. + +**Figure 10-4 – Functional model of MAC** + +In the transmit direction, MPDUs are assembled from LPDUs passed over the x2 reference point. Then the MPDUs are scheduled for transmission using one of the medium access procedures described in clause 10.2. For scheduling, one or more transmission queues can be established. The carrier sense (CRS) primitive indicates whether the medium is busy or not. After being scheduled for transmission, the MPDU is passed to the PHY across the PMI. The octet 0 of the LPH of the LPDU#1 of the MPDU (see Figure 8-9 of [ITU-T G.9961]) shall be passed to the PHY first. + +When the MPDU transmission requires usage of the RTS/CTS protocol, the DLL management shall instruct the MAC to schedule an RTS prior to passing the MPDU to the PHY. The scheduled MPDU will be passed to the PHY only if a correct CTS PHY frame was received (see clause 8.3.3.4.4 of [ITU-T G.9961]). + +The MAC also schedules transmission of priority resolution (PR) and INUSE signals to support media access protocols described in clause 10.2 if these signals are required. + +The MAC is also responsible for scheduling an ACK frame transmission by the PHY if ACK is required. + +In the receive direction, the incoming MPDU is disassembled and the resulting LPDUs are passed to the LLC over the x2 reference point. + +#### 10.1.4.1 Assembling of an MPDU from LPDUs + +See clause 8.1.4.1 of [ITU-T G.9961]. + +## 10.2 Medium access + +### 10.2.1 MAP controlled medium access + +See clause 8.2 of [ITU-T G.9961]. + +### 10.2.2 Transmission opportunities (TXOPs) and time slots (TSs) + +The MAC cycle includes one or more transmission opportunities (TXOPs) of different types. The following types of TXOPs are defined: + +- contention-free TXOP (CFTXOP) +- shared TXOP (STXOP) +- full duplex contention-free TXOP (FDCFTXOP) +- full duplex shared TXOP (FDSTXOP). + +An STXOP is divided into one or more time slots (TSs) where each TS represents an opportunity to start transmitting for the node or nodes assigned to this TS. A node assigned to the TS may either use the opportunity to start transmitting during the TS, or pass on the opportunity to transmit. + +Transmission rules within a TS depend on the type of the TS. If the node passes on the opportunity, it shall wait until the next opportunity to transmit in a subsequent TS assigned for this node. The duration of a TS (TS\_DURATION) is medium-dependent and is defined in clause 8.4. + +An STXOP can contain the following types of TSs: + +- contention-free TS (CFTS) +- contention-based TS (CBTS). + +An STXOP can be composed of only CFTSs, only CBTSs, or both CFTSs and CBTSs. An STXOP that is composed of CBTSs only is denoted as CBTXOP. + +An example of a MAC cycle composed of TXOPs of different types is illustrated in Figure 10-5. + +![Figure 10-5 – Example of a MAC cycle structure. The diagram shows a horizontal sequence of blocks representing a MAC cycle. The blocks are: CFTXOP (orange), STXOP (light blue), MAP (yellow), CFTXOP (orange), STXOP (light blue), FDCFTXOP (orange), CBTXOP (light blue), FDSTXOP (light blue), and STXOP (light blue). A double-headed arrow labeled 'MAC cycle' spans the entire sequence. Below the first STXOP, a callout shows four small boxes, with the first three labeled 'STXOP with CFTSs'. Below the second STXOP, a callout shows four small boxes, with the first three labeled 'STXOP with CFTSs and CBTSs'. The text 'G.9991(19)_F10-5' is in the bottom right corner.](c0c7f65c51c83fbe595b47326f6b089a_img.jpg) + +Figure 10-5 – Example of a MAC cycle structure. The diagram shows a horizontal sequence of blocks representing a MAC cycle. The blocks are: CFTXOP (orange), STXOP (light blue), MAP (yellow), CFTXOP (orange), STXOP (light blue), FDCFTXOP (orange), CBTXOP (light blue), FDSTXOP (light blue), and STXOP (light blue). A double-headed arrow labeled 'MAC cycle' spans the entire sequence. Below the first STXOP, a callout shows four small boxes, with the first three labeled 'STXOP with CFTSs'. Below the second STXOP, a callout shows four small boxes, with the first three labeled 'STXOP with CFTSs and CBTSs'. The text 'G.9991(19)\_F10-5' is in the bottom right corner. + +**Figure 10-5 – Example of a MAC cycle structure** + +At least one MAP shall be sent each MAC cycle in a dedicated CFTXOP assigned by the domain master. This MAP shall be transmitted via a MAP-A frame (see clause 10.7.1). + +The domain master shall plan medium access during a MAC cycle by dividing the available medium access time within the MAC cycle time into TXOPs. The domain master shall partition the MAC cycle into CFTXOPs, STXOPs, optional FDCFTXOP and optional FDSTXOP. + +NOTE – The above partitioning should be done in accordance with service requirements of network nodes and domain scheduling decisions. + +Medium access within STXOPs shall be performed using CFTSs and CBTSs. Each STXOP may contain zero, one or more CFTSs, each assigned to a given node. Similarly, each STXOP may contain zero, one, or more CBTSs, and each CBTS is assigned to several nodes potentially contending for this CBTS. Within an STXOP with no CFTS (i.e., a CBTXOP), medium access in the CBTS could be implemented as described in clause 10.2.2.3.4, or could be implemented as described in clause 10.2.2.3.8. + +An FDCFTXOP shall be assigned to either a pair of nodes or three nodes. If an FDCFTXOP is assigned to a pair of nodes, simultaneous transmission and reception between these two nodes is allowed; if an FDCFTXOP is assigned to three nodes, one of these nodes is appointed as the central node, which is allowed to transmit to another node and receive from the third node simultaneously. All transmissions in the FDCFTXOP shall be contention-free. + +An FDSTXOP shall be assigned to a group of nodes, one of which is appointed as the central node, which is fixed and allowed to transmit to another node and receive from the third node simultaneously. In the transmit direction, the central node shall transmit in a contention-free manner, while in the receive direction, other nodes shall share the TXOP to transmit to the central node. + +The type, placement and duration of TXOPs within a MAC cycle and the order of the TSs inside a STXOP is assigned by the domain master according to internal scheduling decisions, which are beyond the scope of this Recommendation. + +The format for describing the TXOPs and TS assignments in the MAP is described in clause 10.7. + +#### **10.2.2.1 Assignment of nodes and connections to TXOPs and TSs** + +See clause 8.3.1 of [ITU-T G.9961]. + +#### **10.2.2.2 TXOP and TS attributes** + +See clause 8.3.2 of [ITU-T G.9961]. + +#### **10.2.2.3 Medium access in STXOPs** + +An STXOP may contain zero, one or more than one TSs of CFTS or CBTS type. + +Each TS inside an STXOP is identified by its order within the STXOP. Each CFTS may be assigned to: + +- a single source node and a minimum user priority identified by the tuple (SID, PRI); or +- a data connection that a single source node originates, identified by the tuple (SID, FLOW\_ID); or +- a single source node, a single destination node and a minimum user priority identified by the tuple (SID, DID, PRI). + +A CBTS is assigned to a group of nodes as described in clause 10.7.4.1.5 and a minimum user priority as described in clause 10.7.4.2. The order in which TSs appear, and how nodes, connections or user priorities are assigned to them, is based on a scheduling policy used by the domain master. Those scheduling policies are beyond the scope of this Recommendation. + +An STXOP is divided into a grid of TSs providing transmission opportunities to the nodes sharing the STXOP. The grid starts at the beginning of an STXOP and the grid timing is reset after each transmission as described in clause 10.2.2.3.1 below. + +Nodes that share an STXOP shall track the passage of TSs on the line using carrier sensing and transmit only within their assigned TS. + +In an STXOP with no CFTS (i.e., CBTXOP), if the 'CBTXOP indicator' in the basic TXOP descriptor is set to one, nodes assigned to each CBTS in the STXOP shall be the same group of nodes which is identified as described in clause 10.7.4.1.6, and nodes shall track the passage of TSs on the line using a different way from that described from clauses 10.2.2.3.1 to 10.2.2.3.6. + +##### **10.2.2.3.1 TS size and timing** + +See clause 8.3.3.1 of [ITU-T G.9961]. + +##### **10.2.2.3.2 TS assignment rules** + +See clause 8.3.3.2 of [ITU-T G.9961]. + +##### **10.2.2.3.3 Transmission in CFTS** + +See clause 8.3.3.3 of [ITU-T G.9961]. + +##### **10.2.2.3.4 Transmission in CBTS** + +See clause 8.3.3.4 of [ITU-T G.9961]. + +##### **10.2.2.3.5 Enhanced frame detection (EFD) TXOP** + +See clause 8.3.3.5 of [ITU-T G.9961]. + +##### 10.2.2.3.6 TS grid synchronization loss and recovery + +See clause 8.3.3.6 of [ITU-T G.9961]. + +##### 10.2.2.3.7 Silent TXOP or TS + +See clause 8.3.3.7 of [ITU-T G.9961]. + +##### 10.2.2.3.8 Medium access in CBTXOP using DQ-based mechanism + +If the STXOP contains CBTS only and the 'CBTXOP indicator' in the basic TXOP descriptor is set to one, nodes assigned to each CBTS in the CBTXOP shall be the same group of nodes and shall contend for the medium as described in this clause. + +A contending node shall first send an access request (AR) to the DM. The transmission of the contending node shall be allowed only after the AR is successfully received by the DM. + +Collisions may occur when a node is transmitting the AR to the DM. If collision occurs, the node shall enter the collision resolution queue (CRQ) and wait for its turn to retransmit the AR. Each node and the DM shall maintain a collision resolution queue (CRQ) to manage and resolve the collisions. + +After the AR is successfully received by the DM, the node shall enter the data transmission queue (DTQ) and wait its turn to send the MSG frame to the DM in a contention-free manner. Each node and the DM shall maintain a data transmission queue (DTQ) to manage the transmission of MSG frames. + +The detail of maintaining the CRQ and the DTQ shall be described in clause 10.2.2.3.8.2. + +The acknowledgement to the reception of the ARs and the MSG frame shall be broadcasted to the contending nodes by the DM in an ACK frame and an IND frame. The nodes assigned to the CBTXOP shall manage and update their CRQs and DTQs based on the ACK frame and the IND frame. + +###### 10.2.2.3.8.1 Transmissions in CBTXOP + +Transmission within the CBTXOP is illustrated as shown in Figure 10-6. The CBTXOP shall be divided into multiple TSs and each TS further includes one access channel, one (or zero) transmission channel and the transmission of one ACK frame and one IND frame. The access channel shall further contain three contention slots among which each node shall randomly choose one contention slot and send the access request (AR) to the DM on the chosen contention slot. The length of the contention slot shall be $T_{cshd}$ (see clause 10.3). + +![Figure 10-6: Half duplex transmission in the CBTXOP. The diagram shows two time slots, TS 1 and TS 2. TS 1 consists of an 'Access channel' with three 'Contention slot' units (labeled 1, 2, and 3) for sending 'AR' (Access Request) frames, followed by an 'AIFG' (Arbitration Interframe Gap) and an 'ACK 1' frame. Below the contention slots, a status box indicates: 'Contention slot 1: collision', 'Contention slot 2: collision', and 'Contention slot 3: idle'. TS 2 consists of an 'Access channel' with three 'Contention slot' units for 'AR' frames, followed by a 'Transmission channel' for a 'MSG' (Message) frame, then an 'AIFG', 'ACK 2', and 'IND' (Indication) frames. Below the contention slots in TS 2, a status box indicates: 'Contention slot 1: collision', 'Contention slot 2: successful', and 'Contention slot 3: idle'. Vertical red arrows point from the ACK frames to their respective status boxes. Timing parameters like T_{IFG\_MIN} are indicated between frames.](1a1484a99fee36bd3ca4e40fe1538bf8_img.jpg) + +Figure 10-6: Half duplex transmission in the CBTXOP. The diagram shows two time slots, TS 1 and TS 2. TS 1 consists of an 'Access channel' with three 'Contention slot' units (labeled 1, 2, and 3) for sending 'AR' (Access Request) frames, followed by an 'AIFG' (Arbitration Interframe Gap) and an 'ACK 1' frame. Below the contention slots, a status box indicates: 'Contention slot 1: collision', 'Contention slot 2: collision', and 'Contention slot 3: idle'. TS 2 consists of an 'Access channel' with three 'Contention slot' units for 'AR' frames, followed by a 'Transmission channel' for a 'MSG' (Message) frame, then an 'AIFG', 'ACK 2', and 'IND' (Indication) frames. Below the contention slots in TS 2, a status box indicates: 'Contention slot 1: collision', 'Contention slot 2: successful', and 'Contention slot 3: idle'. Vertical red arrows point from the ACK frames to their respective status boxes. Timing parameters like $T_{IFG\_MIN}$ are indicated between frames. + +G.9991(19)\_F10-6 + +**Figure 10-6 – Half duplex transmission in the CBTXOP** + +The transmission channel shall start following the end of the access channel if the access channel exists and shall contain one transmission slot where the node shall send one MSG frame to the DM in a contention free manner. The length of the transmission channel shall be accommodated to the duration of the MSG frame sent by the node and it may vary in each TS. + +The transmission channel shall exist only when the DTQ is not empty. The first TS in the CBTXOP shall always contain no transmission channel. For other TSs in the CBTXOP, the DM shall indicate to the nodes whether there is a transmission channel or not in the next TS in the current ACK frame. + +If the transmission channel exists in the TS (e.g., TS 2 in Figure 10-6), the transmission of the ACK frame shall begin one AIFG after the end of the transmission channel; otherwise, the transmission of the ACK frame shall begin one AIFG after the end of the access channel (e.g., TS 1 in Figure 10-6). The ACK frame shall be broadcasted by the DM to the nodes and shall indicate the acknowledgement to the ARs sent on the access channel, the acknowledgement to the MSG frame sent on the transmission channel (if there is a transmission channel in the TS) as well as the existence of the transmission channel in the next TS. If the status of at least one contention slot is indicated as "successful" by the DM in the ACK frame, then then DM shall begin the transmission of the IND frame one AIFG after the end of the transmission of the ACK frame. The IND frame shall indicate the DEVICE\_ID(s) of the node(s) which has (have) send the AR(s) that has (have) been received successfully by the DM in the contention slot(s) of which the status is indicated as "successful". Nodes shall update the CRQ and the DTQ accordingly based on the ACK frame and the IND frame as described in clause 10.2.2.4.2. + +Next TS shall always start one $T_{IFG\_MIN}$ after the end of the transmission of the IND frame (or the ACK frame). Nodes shall keep tracking the TSs by detecting the ACK frames and the IND frames. The DM shall make sure the last TS complete before the end of the CBTXOP. + +The AR sent on the access channel shall be an RTS frame with the 'FDI' field in the frame header set to '10' as described in clause 8.1.2.3.2.4.4. + +The 'FDI' field in the frame header of the ACK frame shall be set to '10' as described in clause 8.1.2.3.2.3.8. The 'ACKDATA' field in the ACK frame shall indicate the reception status of the MSG frame sent on the transmission channel if there is a transmission channel in the TS. + +###### **10.2.2.3.8.2 Operation of the CRQ and the DTQ** + +Transmissions in the CBTXOP shall be accompanied by the operation of the CRQ and DTQ. + +Both of the CRQ and DTQ shall be maintained by each node and the DM with two integer numbers: + +- the length of the queue, RQ counter for CRQ and TQ counter for DTQ respectively +- the position of each node in the queue, pRQ counter and pTQ counter respectively. + +Nodes and the DM shall initialize the RQ counter, TQ counter, pRQ counter and pTQ counter to zero at the beginning of each CBTXOP. + +A node shall enter the CRQ when collision occurs in the contention slot which is chosen by the node to send the AR. A node shall enter the DTQ when the node has sent the AR to the DM successfully. Nodes in the CRQ and nodes in the DTQ shall line up according to the rule of first come first served and update their RQ counters, TQ counters, pRQ counters and pTQ counters based on the ACK frame sent by the DM as follows. + +When a TS begins, if the 'CRQLength' field in the previous ACK frame is set to zero, all nodes identified by the CBTS nodes information extension are allowed to send ARs to the DM. If the nodes that are allowed to send ARs to the DM have MSG frames needed to be sent to the DM, they shall each choose a contention slot randomly among the 3 contention slots and send their ARs to the DM in the chosen slots. Otherwise, if the 'CRQLength' field in the previous ACK frame is set to a non-zero value, only nodes belonging to the head of the CRQ are allowed to retransmit ARs to the DM and other nodes queued in the CRQ shall decrease their pRQ counters by one. Nodes that are allowed to + +retransmit ARs to the DM shall each choose a contention slot randomly among the 3 contention slots and retransmit their ARs to the DM in the chosen slots. + +When the access channel ends, if the 'TCI' field in the previous ACK frame is set to '1', the transmission channel shall begin right after the end of the access channel and the node identified by the 'HeadDTQ' field in the previous ACK frame shall send an MSG frame to the DM on the transmission channel. Other nodes in the DTQ shall decrease their pTQ counters by one. + +After the transmission channel ends (or after the access channel ends if there is no transmission channel in the TS), the DM shall broadcast an ACK frame to the nodes with the 'FDI' field in the frame header set to '10'. + +The ACK frame shall convey the acknowledgement to the ARs sent on the access channel as well as the acknowledgement to the MSG frame sent on the transmission channel. If there is no transmission channel in the TS, the acknowledgement data to the MSG frame shall not be included in the ACK frame. + +Acknowledgement to the ARs shall be indicated by the status of each contention slots in the access channel which could be 'idle', 'successful' or 'collision'. If a valid preamble is detected by the DM in the contention slot but a valid PHY frame header is not detected by the DM, then the status of this contention slot shall be "collision". If a valid preamble is detected by the DM in the contention slot and a valid PHY frame header is also detected by the DM, then the status of this contention slot shall be "successful". If no valid preamble is detected by DM in the contention slot, then the status of this contention slot shall be "idle". + +The ACK frame shall also include an acknowledgement to the MSG frame sent by the node on the transmission channel (if the transmission channel exists in the TS) and the format of the acknowledgement shall be described in clause 8.1.2.3.2.3. + +The ACK frame shall also indicate the existence of the transmission channel in the next TS by setting the 'TCI' field. If the 'DTQLength' field indicates an empty DTQ, there shall be no transmission channel in the next TS and the 'TCI' field in the ACK frame shall be set to zero; otherwise, if the 'DTQLength' field indicates a non-empty DTQ, there shall be a transmission channel in the next TS and the 'TCI' field in the ACK frame shall be set to one. + +If the status of at least one contention slot is indicated as "successful" by the DM in the ACK frame, the DM shall broadcast an IND frame to the nodes one AIFG after the end of the transmission of the ACK frame. The IND frame shall indicate the DEVICE\_ID(s) of the specific node(s) which has (have) sent the AR(s) that has (have) been received successfully by the DM in the contention slot(s) of which the status is indicated as "successful". The node(s) which has (have) sent AR(s) in a contention slot of which the status is indicated as "successful" shall compare the DEVICE\_ID(s) with its (their) own DEVICE\_ID(s) so as to determine whether there is a detection error occurred at the DM. + +Nodes shall update their RQ counters and TQ counters based on the ACK frame and the IND frame. Each node shall set its RQ counter to 'CRQLength' and set its TQ counter to 'DTQLength'. If the 'Status' field in the ACK frame indicates there are $M$ ( $0 \leq M \leq 3$ ) contention slots of which the status is 'successful', $N$ ( $0 \leq N \leq 3$ ) contention slots of which the status is 'collision' and $K$ ( $0 \leq K \leq 3$ ) contention slots of which the status is 'idle', then each node which has sent an AR in contention slot $X$ ( $X = 1, 2, 3$ ) of the access channel in the current TS shall update its pRQ counter and pTQ counter according to the following rules: + +- If the chosen contention slot $X$ by the node is the $i^{\text{th}}$ ( $1 \leq i \leq M$ ) contention slot among the $M$ contention slots of which the status is 'successful', then the node shall wait to receive the following IND frame sent by the DM and determine whether the AR sent by itself is received successfully or not by comparing its own DEVICE\_ID with the value of 'Node[X]' field in the IND frame. The node shall set its pTQ counter to $DTQLength - M + i$ if the two DEVICE\_IDs are matched; otherwise, the node shall infer a detection error in the contention + +slot X of the channel and shall set its pRQ value based on the number of collisions newly occurred (N) and the CRQ status in the current TS. If N is equal to 0 and the CRQ is not empty, the node shall line up at the last place of the CRQ. If N is equal to 0 and the CRQ is empty, the node shall resend the AR in the next TS without entering the CRQ. If N is equal to one, the node shall have the same position in the CRQ as those nodes which have sent ARs in the only contention slot indicated as "collision" in current TS. If N is equal to two, the node shall have the same position in the CRQ as those nodes which have sent ARs in the contention slot of which the status is indicated as "collision" in the current TS and that is closer to contention slot X in the time axis among the two contention slots indicated. If the two contention slots have the same distance towards contention slot X in the time axis, the earlier one shall be chosen by the node. + +- If the chosen contention slot X by the node is the $j^{\text{th}}$ ( $1 \leq j \leq N$ ) contention slot among the N contention slots of which the status is 'collision', then the node shall set its pRQ counter to $\text{CRQLength} - N + j$ . +- If the chosen contention slot X by the node is indicated as 'idle', the node shall infer a detection error at the DM. The node shall set its pRQ value based on the number of collisions newly occurred (N) and the CRQ status in the current TS. If N is equal to 0 and the CRQ is not empty, the node shall line up at the last place of the CRQ. If N is equal to 0 and the CRQ is empty, the node shall resend the AR in the next TS without entering the CRQ. If N is equal to one, the node shall have the same position in the CRQ as those nodes which have sent ARs in the only contention slot indicated as "collision" in the current TS. If N is equal to two, the node shall have the same position in the CRQ as those nodes which have sent ARs in the contention slots of which the status is indicated as "collision" and that is closer to contention slot X in the time axis among the two contention slots indicated. If the two contention slots have the same distance towards contention slot X in the time axis, the earlier one shall be chosen by the node. + +The above steps shall repeat in each TS within the CBTXOP till the end of the CBTXOP. + +#### 10.2.2.4 Medium access in CFTXOPs + +See clause 8.3.4 of [ITU-T G.9961]. + +#### 10.2.2.5 Medium access in FDSTXOP + +The FDSTXOP shall be scheduled for asymmetrical full duplex transmissions, of which the primary transmission is contention-free and the secondary transmission is contention-based. + +The primary transmission within an FDSTXOP shall be assigned to the central node for contention free transmission to the primary receiver on the primary channel as described in clause 10.2.2.5.1. The secondary transmission shall be assigned to a group of candidate secondary transmitters identified by the FD contention group information extension in the FDSTXOP descriptor for contention-based transmission on the secondary channel. + +When a candidate secondary transmitter needs to send MSG frames to the central node, it shall first send an access request (AR) to the central node in a contention-base manner. The candidate secondary transmitter shall become the secondary transmitter and be allowed to transmit the MSG frame to the central node only after the AR is received successfully by the central node. Collisions may occur when the candidate secondary transmitter is transmitting the AR to the central node. If collision occurs, the candidate secondary transmitter shall enter the collision resolution queue (CRQ) to wait for its turn to retransmit the AR. If the AR is received successfully by the central node, the candidate secondary transmitter shall become the secondary transmitter and enter the data transmission queue (DTQ) to wait its turn to send the MSG frame to the central node in a contention-free manner. + +Each candidate secondary transmitter and the central node shall maintain a collision resolution queue (CRQ) to manage and resolve the collisions occurred. Each secondary transmitter and the central + +node shall maintain a data transmission queue (DTQ) to manage the transmission of MSG frames. The detail of maintaining the CRQ and the DTQ shall be as described in clause 10.2.2.5.2. + +The secondary channel in the FDSTXOP shall be divided into multiple secondary transmission windows (STWs) discontinuously. As shown in Figure 10-7, each STW corresponds to an MSG frame that is transmitted on the primary channel and the duration of each STW is constrained by the duration of the corresponding transmission of the MSG frame sent on the primary channel. The STW shall always start $T_0$ later than the starting time of the primary transmission and end no later than the ending time of the primary transmission. The ending time of the STW shall be indicated in the MSG frame header (see clause 8.1.2.3.3.1). + +![Figure 10-7: An example of full duplex transmission in FDSTXOP. The diagram illustrates the timing relationship between primary and secondary transmissions. It features three horizontal axes representing time (t). The top axis, 'Primary Rx', shows two blue-outlined boxes labeled 'ACK 1' and 'ACK 2'. The middle axis, 'Central node (primary Tx and secondary Rx)', shows two blue-outlined boxes labeled 'MSG 1' and 'MSG 2' on the primary channel, and two red-outlined boxes labeled 'ACK 3' and 'ACK 4' on the secondary channel. Below 'MSG 1' and 'MSG 2', there are indicators 'FDI = \'01\' '. The bottom axis, 'Secondary Txs', shows two 'STW' periods. Each STW starts after a delay 'T0' from the start of the corresponding primary MSG frame. Within each STW, there is an 'Access channel' containing three cross-hatched 'Contention slots' and a 'Transmission channel' containing a red-outlined box labeled 'MSG 3' or 'MSG 4'. Vertical dashed lines indicate the synchronization between the primary MSG frames, the secondary STWs, and the subsequent ACK frames. The diagram is labeled G.9991(19)_F10-7.](01832e59ebad7ada5e790de6f90cc9b6_img.jpg) + +Figure 10-7: An example of full duplex transmission in FDSTXOP. The diagram illustrates the timing relationship between primary and secondary transmissions. It features three horizontal axes representing time (t). The top axis, 'Primary Rx', shows two blue-outlined boxes labeled 'ACK 1' and 'ACK 2'. The middle axis, 'Central node (primary Tx and secondary Rx)', shows two blue-outlined boxes labeled 'MSG 1' and 'MSG 2' on the primary channel, and two red-outlined boxes labeled 'ACK 3' and 'ACK 4' on the secondary channel. Below 'MSG 1' and 'MSG 2', there are indicators 'FDI = \'01\' '. The bottom axis, 'Secondary Txs', shows two 'STW' periods. Each STW starts after a delay 'T0' from the start of the corresponding primary MSG frame. Within each STW, there is an 'Access channel' containing three cross-hatched 'Contention slots' and a 'Transmission channel' containing a red-outlined box labeled 'MSG 3' or 'MSG 4'. Vertical dashed lines indicate the synchronization between the primary MSG frames, the secondary STWs, and the subsequent ACK frames. The diagram is labeled G.9991(19)\_F10-7. + +**Figure 10-7 – An example of full duplex transmission in FDSTXOP** + +An STW may contain zero or one access channel and one transmission channel. The access channel shall further include three contention slots among which the candidate secondary transmitters shall choose one contention slot randomly and send their access requests (ARs) to the central node on the chosen contention slots. The length of the contention slot shall be $T_{csfd}$ (see clause 10.3). The transmission channel shall contain one transmission slot where the secondary transmitter shall send an MSG frame to the central node in a contention free manner. If the STW contains an access channel, the transmission channel shall begin at the same time as the access channel ends; otherwise, the transmission channel shall begin at the same time as that of the STW. The duration of the transmission channel in each STW may vary with the durations of the primary transmissions. + +The candidate secondary transmitters shall send the ARs to the central node on the access channel and the secondary transmitter shall send the MSG frame to the central node on the transmission channel within the STW while the primary transmission is ongoing. + +One AIFG after the ending time of the primary transmission, the primary receiver shall send an ACK frame to the central node, while the central node shall send an ACK frame to the candidate secondary transmitters and the secondary transmitters at the same time, with the feedback notification encapsulated in the frame header of the ACK frame. + +The above steps shall repeat in each STW within the FDSTXOP till the end of the FDSTXOP. + +The central node may transmit multiple MSG frames to the primary receiver on the primary channel within the FDSTXOP, thus there might be multiple STWs within the FDSTXOP. + +The central node shall make sure the last STW and the transmission of its corresponding ACK frame complete before the end of the FDSTXOP. + +##### 10.2.2.5.1 Primary transmission in FDSTXOP + +The primary transmission shall be assigned to the central node for contention free transmission and the connections belonging to the primary transmission shall be identified by the following tuples: + +- the DEVICE\_ID of the central node and a minimum user priority (SID, PRI); or +- the DEVICE\_ID of the central and the flow that the central node originates (SID, FLOW\_ID); or +- the DEVICE\_ID of the central node, a single destination node and a minimum user priority (SID, DID, PRI). + +The domain master shall indicate the tuple in the FDSTXOP descriptor by setting the 'FD TXOP descriptor' to one and the 'SID' field to the DEVICE\_ID of the central node. + +The DM shall guarantee the connection assigned to the primary transmission of the FDSTXOP be a connection using the Imm-ACK protocol. + +##### 10.2.2.5.2 Secondary transmission in FDSTXOP + +Secondary transmissions in the FDSTXOP shall be accompanied by the operation of the CRQ and DTQ. + +The CRQ shall be maintained by each candidate second transmitter and by the central node. The DTQ shall be maintained by each secondary transmitter and by the central node. Both the CRQ and the DTQ shall be maintained with two integer numbers: + +- the length of the queue, RQ counter for CRQ and TQ counter for DTQ respectively; +- the position of each node in the queue, pRQ counter and pTQ counter respectively. The pTQ counter maintained by the central node shall record each secondary transmitter's position in the DTQ counter. Note that the central node shall not maintain the pRQ counter. + +The RQ counter, TQ counter, pRQ counter and pTQ counter shall be initialized to zero at the beginning of each FDSTXOP. Once the candidate secondary transmitters enter the CRQ or the secondary transmitters enter the DTQ, they shall line up according to the rule of first come first served. The secondary transmitters (including the candidate secondary transmitters) and the central node shall track and update the RQ counter, TQ counter, pRQ counter and pTQ counter as follows. + +Candidate secondary transmitters and secondary transmitters shall keep tracking the STWs within the FDSTXOP by detecting the frame header of the MSG frame sent by the central node. When a valid frame header of the MSG frame sent by the central node is detected within the FDSTXOP, the candidate secondary transmitters and secondary transmitters shall parse the frame header to obtain the secondary transmission information encapsulated in the E\_FTSF field of the MSG frame (see clause 8.1.2.3.3.1.1). The secondary transmission information includes: the DEVICE\_ID of the candidate secondary transmitter that has sent an AR that has been received successfully by the central node, the configuration information of the STW which indicates the number of the contention slots (three or none) in the access channel, the ending time of the STW, the candidate secondary transmitters allowed to transmit ARs on the access channel and the DEVICE\_ID of the secondary transmitter which is scheduled to transmit the MSG frame to the central node on the transmission channel. + +The 'NewSecTx[i]' ( $i \leq i \leq 3$ ) field (see clause 8.1.2.3.3.1.1.5) shall indicate the DEVICE\_ID of the candidate secondary transmitter which has sent an AR that has been received successfully by the central node in contention slot $i$ of the previous access channel. If the feedback notification that corresponds to the previous access channel indicates the status of contention slot $i$ ( $i \leq i \leq 3$ ) is successful, the candidate secondary transmitters which have sent ARs in contention slot $i$ of the previous access channel shall compare their DEVICE\_IDs with the value of 'NewSecTx[i]'. The candidate secondary transmitter shall become a secondary transmitter and enter the DTQ if its own + +DEVICE\_ID matches NewSecTx[i]; otherwise, the candidate secondary transmitter shall infer a detection error occurred at the central node. + +If the 'NumberContentionSlots' field (see clause 8.1.2.3.3.1.1.3) in the MSG frame indicates 3 contention slots, then the STW shall begin with an access channel and the candidate secondary transmitters that are allowed to send ARs shall send ARs to the central node on the access channel. If the 'EmptyCRQFlag' field (see clause 8.1.2.3.3.1.1.2) indicates an empty CRQ, then all of the candidate secondary transmitters are allowed to send ARs to the central node in the access channel. Candidate secondary transmitters that are allowed to send ARs and have MSG frames needed to be sent to the central node shall each choose a contention slot randomly among the 3 contention slots and send their ARs to the central node in the chosen slot. If the 'EmptyCRQFlag' field (see clause 8.1.2.3.3.1.1.2) indicates a non-empty CRQ, then the candidate secondary transmitters belonging to the head of the CRQ are allowed to send ARs to the central node in the access channel and other candidate secondary transmitters queued in the CRQ shall decrease their pRQ counters by one. Candidate secondary transmitters that are allowed to send ARs shall each choose a contention slot randomly among the 3 contention slots and send their ARs to the central node in the chosen slots. + +If the 'NumberContentionSlots' field (see clause 8.1.2.3.3.1.1.3) in the detected secondary transmission information indicates zero contention slot, there shall be no access channel in the STW and no ARs shall be send in the current STW. + +The AR shall be an RTS frame with the 'FDI' field in the frame header set to '01' (see clause 8.1.2.3.2.4). + +The central node shall determine the status of each contention slot in the STW. The status of each contention slot could be 'idle', 'successful' or 'collision'. If a valid preamble is detected by the central node in the contention slot but a valid PHY frame header is not detected by the central node, then the status of this contention slot shall be "collision". If a valid preamble is detected by the central node in the contention slot and a valid PHY frame header is also detected by the central node, then the status of this contention slot shall be "successful". If no valid preamble is detected by the central node in the contention slot, then the status of this contention slot shall be "idle". + +When the secondary transmitters determine the transmission channel in the STW begins, the secondary transmitter indicated by the 'HeadDTQ' field shall send an MSG frame to the central node on the transmission channel. The secondary transmitter shall make sure that the transmission ends no later than the 'Ending\_Time'. Other secondary transmitters queued in the DTQ shall decrease their pTQ counters by one. + +One AIFG after the ending time of the primary transmission, when the primary receiver is sending the ACK frame to the central node on the primary channel, the central node shall send an ACK frame to the candidate secondary transmitters and the secondary transmitters on the secondary channel at the same time. The feedback notification shall be encapsulated in the frame header of the ACK frame sent by the central node, with the 'FDI' field in the frame header set to '01' and the 'DID' field in the frame header set to '252'. + +The feedback notification shall indicate the status of each contention slot of the access channel in the STW and the acknowledgement to the MSG frame sent by the secondary transmitter on the transmission channel. Each candidate secondary transmitter shall set its RQ counter to CRQLength and each secondary transmitter shall set its TQ counter to DTQLength. If the 'Status' field in the feedback notification indicates that there are $M$ ( $0 \leq M \leq 3$ ) contention slots of which the status is 'successful', $N$ ( $0 \leq N \leq 3$ ) contention slots of which the status is 'collision' and $K$ ( $0 \leq K \leq 3$ ) contention slots of which the status is 'idle', then each candidate secondary transmitter which has sent an AR in contention slot $X$ ( $X = 1, 2, 3$ ) shall update its pRQ counter and pTQ counter according to the following rules: + +- If the chosen slot by the candidate secondary transmitter is the $i^{\text{th}}$ ( $0 \leq i \leq M$ ) contention slot among the $M$ contention slots of which the status is indicated as 'successful', the candidate + +secondary transmitter shall wait to receive the next MSG frame sent by the central node and determine whether the AR sent by itself is received successfully or not by comparing its own DEVICE\_ID with the 'NewSecTx[X]' field encapsulated in the MSG frame. The candidate secondary transmitter shall become a secondary transmitter and shall set its pTQ to $DTQLength - M + i$ if its own DEVICE\_ID matches NewSecTx[X]; otherwise, the candidate secondary transmitter shall infer a detection error in contention slot X of the previous access channel and shall set its pRQ value based on the number of collisions newly occurred (N) in the previous access channel and the CRQ status in the current access channel. If N is equal to 0 and the CRQ is not empty, the candidate secondary transmitter shall line up at the last place of the CRQ. If N is equal to 0 and the CRQ is empty, the candidate secondary transmitter shall resend the AR in the current access STW without entering the CRQ. If N is equal to one, the candidate secondary transmitter shall have the same position in the CRQ as those candidate secondary transmitters which have sent ARs in the only contention slot of which the status is indicated as "collision" in the previous access channel. If N is equal to two, the candidate secondary transmitter shall have the same position in the CRQ as those candidate secondary transmitters which have sent ARs in the contention slot of which the status is indicated as "collision" in the previous access channel and that is closer to contention slot X in the time axis among the two contention slots indicated. If the two collisions have the same distance towards contention slot X in the time axis, the earlier one shall be chosen by the candidate secondary transmitter. + +- If the chosen slot by the candidate secondary transmitter is the $j^{\text{th}}$ ( $0 \leq j \leq N$ ) contention slot among the N contention slots of which the status is indicated as 'collision', then the candidate secondary transmitter shall set its pRQ to $CRQLength - N + j$ . If the chosen slot by the candidate secondary transmitter is indicated as 'idle', the candidate secondary transmitter shall infer a detection error at the central node. The candidate secondary transmitter shall set its pRQ value based on the number of collisions newly occurred (N) and the CRQ status in the current access channel. If N is equal to 0 and the CRQ is not empty, the candidate secondary transmitter shall line up at the last place of the CRQ. If N is equal to 0 and the CRQ is empty, the candidate secondary transmitter shall resend the AR in the next access channel without entering the CRQ. If N is equal to one, the candidate secondary transmitter shall have the same position in the CRQ as those candidate secondary transmitters which have sent ARs in the only contention slot of which the status is indicated as "collision" in the current access channel. If N is equal to two, the candidate secondary transmitter shall have the same position in the CRQ as those candidate secondary transmitters which have sent ARs in the contention slot of which the status is indicated as "collision" and that is closer to contention slot X in the time axis among the two contention slots indicated. If the two collisions have the same distance towards contention slot X in the time axis, the earlier one shall be chosen by the candidate secondary transmitter. +- If the central node finds out that there is not enough time to transmit all of the accumulated MSG frames of the secondary transmitters in the DTQ by the end of the FDSTXOP, then the central node may not assign contention slots in the STW anymore and the number of the contention slots could be zero. + +#### 10.2.2.6 Medium access in FDCFTXOP + +This clause is for further study. + +#### 10.2.2.7 Transmission using PHY frame bursting + +See clause 8.3.5 of [ITU-T G.9961]. + +#### 10.2.2.8 Scheduled inactivity + +See clause 8.3.6 of [ITU-T G.9961]. + +#### 10.2.2.9 Bidirectional transmissions + +See clause 8.3.7 of [ITU-T G.9961]. + +#### 10.2.2.10 Extended acknowledgements + +See clause 8.3.8 of [ITU-T G.9961]. + +## 10.3 Control parameters for APC, LLC and MAC + +Table 10-1 lists control parameters for the APC, LLC and MAC. + +**Table 10-1 – Parameters for APC, LLC and MAC** + +| Parameter | Description | Parameter value | +|------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------| +| $T_{IFG\_MIN}$ | Duration of inter-frame gap | 29 $\mu s$ | +| CYCLE_MIN | Minimum duration of MAC cycle | 5 ms | +| CYCLE_MAX | Maximum duration of MAC cycle | 100 ms | +| TX_ON | A time window after the start of TS during which a transmission can start | 1 $\mu s$ | +| TS_DURATION | Duration of time slot | 16.64 $\mu s$ | +| $T_{ITS}$ | Duration of idle time slot (ITS) composing the contention window (CW) in CBTS | 16.64 $\mu s$ | +| $T_{AIFG-D}$ | Default value of inter-frame gap before Imm-ACK | 39.68 $\mu s$ | +| $T_{AIFG}$ | Range of values for inter-frame gap before immediate acknowledgment (Note 2) | 5.12 to 39.68 $\mu s$ | +| MIN_SYM_VAR_AIFG | The minimum number of symbols following the header required in a frame to use receiver specific $T_{AIFG}$ , instead of $T_{AIFG-D}$ , as the AIFG gap, between the frame and the following immediate acknowledgment. | 5 | +| $T_{RCIFG}$ | Inter-frame gap between RTS and CTS | 29 $\mu s$ | +| $T_{CCIFG}$ | Inter-frame gap between CTS and MSG frame | 29 $\mu s$ | +| $T_{BM2BAIFG}$ | Inter-frame gap between BMSG and BACK frame | $T_{AIFG}$ | +| $T_{BA2BMIFG}$ | Inter-frame gap between BACK and BMSG frame | $T_{AIFG}$ | +| $T_{BIFG}$ | Inter-frame gap between MSG frames in PHY frame bursting | Note 1 | +| $T_{McAIFG}$ | Inter-frame gap between multicast ACK frames | 5.12 $\mu s$ | +| TICK | The basic MAC resolution (at TXOP level) | 10 ns | +| MAP_TX_SETUP_TIME | The minimum time between the MAP and the MAC cycle it describes | 2 ms | +| MAX_ARQ_SLOTS | Maximum number of Mc-ACK slots in multicast acknowledgment | 7 | +| DEFAULT_TBFFSS_TIMEOUT | Default timeout used for closing the CBTS in "Timeout-based from frame sequence start" mode | 2.5 ms | +| DEFAULT_TBFCSS_TIMEOUT | Default timeout used for closing the CBTS in "Timeout-based from CBTS start" mode | 2.5 ms | + +**Table 10-1 – Parameters for APC, LLC and MAC** + +| Parameter | Description | Parameter value | +|------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------| +| DEFAULT_ERR_CWOI_TIMEOUT | Default timeout for error conditions in "CBTS without INUSE" (see clause 8.3.3.4.5.3 of [ITU-T G.9961]) | 3.61 ms | +| REG_RESP_TIME | The maximum time within which the domain master shall respond to registration request (see clause 8.6.1.1.1 of [ITU-T G.9961]) | 200 ms | +| REG_RETRY_TIMEOUT | Timeout for node to retry registration (see clause 8.6.1.1.1 of [ITU-T G.9961]) | 1 s | +| MAX_REG_ATTEMPTS | Max registration attempts | 4 | +| RES_TIMEOUT | Timeout for resigning node to wait for response from the domain master (see clause 8.6.1.1.3.1 of [ITU-T G.9961]) | 200 ms | +| MAX_RES_ATTEMPTS | Max number of resignation attempts | 4 | +| CNM_TIMEOUT | Timeout associated with release of connections | 200 ms | +| T MCST | the maximum time the transmitter waits for MC_GrpInfoUpdate.cnf from the multicast group receivers, before it may re-transmit the MC_GrpInfoUpdate.ind message | 100 ms | +| N MCST | Maximum number of retransmissions of the MC_GrpInfoUpdate.ind message | 2 | +| TDM_UPDATE | The domain master broadcasts the updated topology information, within this time duration, after receiving topology updates. | 100 ms | +| TN_RSP | A node replies to the request for topology information from the domain master within this time duration, after receiving the request. | 100 ms | +| TUPDATE_MIN | The minimum time a node waits after receiving message TM_DomainRoutingChange.ind from the domain master, before it can send a TM_ReturnDomainTopology.req message to the domain master. | 100 ms | +| INTER_MAP_RMAP_GAP | The minimum gap between the end of a MAP or RMAP frame and the beginning of a subsequent relay of this MAP or RMAP frame. | 1 ms | +| JOIN_INTERVAL_T 0 | The time interval after a node's initialization, during which the node refrains from transmitting and tries to detect MAP frames or RMAP frames associated with the domain that the node intends to join. | 10 s | +| JOIN_INTERVAL_T 2 | The time interval after a node becomes DM, during which the node refrains from registering new nodes while sending MAP-Ds to signal its presence to other possible nodes. | 400 ms | +| SYM_BOOST_TYPE | Valid types of symbol boost | 00 2 , 01 2 | +| SYM_BOOST_AMOUNT | Valid amounts of symbol boost | 0.0 dB, 0.8 dB | +| MAX_RESP_TIME | The maximum time within which a node shall respond to the received management message. | 100 ms | +| MAX_WAIT_TIME | The time that a node shall wait for an expected response after transmitting a management | 200 ms | + +**Table 10-1 – Parameters for APC, LLC and MAC** + +| Parameter | Description | Parameter value | +|-------------------|----------------------------------------------------------------------------------------------------------------|------------------------| +| | message before inferring the loss of the transmitted message or the response from the responding node or both. | | +| $T_{\text{cshd}}$ | The duration of a contention slot in CBTXOP using DQ-based mechanism | 46.08 $\mu\text{s}$ | +| $T_{\text{csfd}}$ | The duration of a contention slot in FDSTXOP | 46.08 $\mu\text{s}$ | + +NOTE 1 – Use of PHY frame bursting for VLC is for further study. +NOTE 2 – A receiving node shall choose a value in this range at the time of registration (see clause 8.6.1.1.4.1 of [ITU-T G.9961]). + +### **10.3.1 General parameters for management message timeout** + +See clause 8.4.1 of [ITU-T G.9961]. + +## **10.4 Functions of the end-point node** + +The following paragraphs list the functions of an end-point node. + +### **10.4.1 MAC cycle synchronization and synchronized transmissions** + +See clause 8.5.1 of [ITU-T G.9961]. + +### **10.4.2 Bandwidth reservation** + +See clause 8.5.2 of [ITU-T G.9961]. + +### **10.4.3 Routing of ADPs** + +For domains operating in CM, see clause 8.5.3 of [ITU-T G.9961]. Domains operating in UM are for further study. + +### **10.4.4 Broadcast of LLC frames** + +The broadcast of LLC frames only applies to the domain operating in UM. + +See clause 8.5.4 of [ITU-T G.9961]. + +### **10.4.5 Reporting of detected neighbouring domains** + +See clause 8.5.5 of [ITU-T G.9961]. + +### **10.4.6 MAP relaying** + +Map relaying only applies to the domain operating in UM. + +See clause 8.5.6 of [ITU-T G.9961]. + +### **10.4.7 Relaying messages** + +Relaying messages only applies to the domain operating in UM. + +See clause 8.5.7 of [ITU-T G.9961]. + +### **10.4.8 Retransmissions and acknowledgement** + +See clause 8.5.8 of [ITU-T G.9961]. + +### **10.4.9 Bidirectional flows** + +See clause 8.5.9 of [ITU-T G.9961]. + +## **10.5 Domain master node functional capabilities** + +See clause 8.6 of [ITU-T G.9961]. + +### **10.5.1 Network admission** + +ITU-T G.9991 network admission shall follow the procedure specified in clause 8.6.1 of [ITU-T G.9961] with the revised capabilities described in Annex C. + +### **10.5.2 Bandwidth management** + +See clause 8.6.2 of [ITU-T G.9961]. + +### **10.5.3 Synchronization to an external source** + +See clause 8.6.3 of [ITU-T G.9961]. + +### **10.5.4 Routing and topology management** + +Routing and topology management only applies to the domain operating in UM. + +See clause 8.6.4 of [ITU-T G.9961]. + +### **10.5.5 Backup domain master** + +Backup domain master only applies to the domain operating in UM. + +See clause 8.6.5 of [ITU-T G.9961]. + +### **10.5.6 Domain master selection** + +Domain master selection only applies to the domain operating in UM. + +See clause 8.6.6 of [ITU-T G.9961]. + +### **10.5.7 Selection of PHY-frame header segmentation** + +See clause 8.6.7 of [ITU-T G.9961]. + +### **10.5.8 Selection of the DNI and the DOD** + +See clause 8.6.8 of [ITU-T G.9961]. + +### **10.5.9 Per-node transmit PSD shaping** + +See clause 8.6.9 of [ITU-T G.9961]. + +### **10.5.10 Selection of initialization seeds used for generating preamble, PR, INUSE, NACK and IDPS signals** + +See clause 8.6.10 of [ITU-T G.9961]. + +## **10.6 Addressing scheme** + +### **10.6.1 Node identifier** + +See clause 8.7.1 of [ITU-T G.9961]. + +#### **10.6.1.1 DEVICE\_ID** + +See clause 8.7.1.1 of [ITU-T G.9961]. + +#### 10.6.1.2 MULTICAST\_ID and BROADCAST\_ID + +MULTICAST\_IDs shall be generated autonomously by the nodes creating multicast groups for the multicast transmission. MULTICAST\_IDs only apply to multicast transmissions among nodes communicating directly (i.e., not via a relay node). A node shall generate a unique MULTICAST\_ID for each multicast group that it creates. The node creating the multicast group shall communicate the MULTICAST\_ID to all multicast destination nodes using the protocol described in clause 10.25 before starting the multicast transmission. As the multicast session is complete, nodes shall terminate the MULTICAST\_ID according to an explicit notification from the node creating the multicast group (see clause 8.16). + +A node may be addressed by multiple MULTICAST\_IDs generated by different nodes for a multicast transmission to this node. The same MULTICAST\_ID can be used as the DID by several nodes for different multicast groups. The differentiation in the receiver is by the SID of the node creating the multicast group. + +The MULTICAST\_ID shall be represented by an 8-bit unsigned integer with valid values in the range from 1 to 254. It is distinguished from a DEVICE\_ID in the PHY-frame header and in the MAP by the multicast indicator described in clause 7.1.2.3.1.5 of [ITU-T G.9960]. + +A BROADCAST\_ID is a MULTICAST\_ID with a fixed value of 255 and shall be used for broadcast transmission only. + +**Table 10-2 – Definition and valid values of node identification parameters** + +| Parameter | Valid values | Description | +|--------------|--------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| DEVICE_ID | 0 | The ID used by a new node joining the network before it is assigned a unique DEVICE_ID by the domain master. The domain master shall not assign the DEVICE_ID = 0 to any node admitted to the network. | +| | 1 to 250 | IDs reserved for assignment by the domain master to nodes admitted to the network. | +| | 251 | The ID used for inter-domain communication | +| | 252 | The ID used for the feedback notification transmitted in the FDSTXOP. | +| | 253 to 255 | Reserved by ITU-T | +| MULTICAST_ID | 0 | Reserved by ITU-T | +| | 1 to 254 | IDs reserved for assignment for multicast traffic | +| BROADCAST_ID | 255 | A special value of MULTICAST_ID reserved for broadcast traffic. | + +### 10.6.2 Flow identifier (FLOW\_ID) + +See clause 8.7.2 of [ITU-T G.9961]. + +## 10.7 Medium access plan (MAP) frame + +See clause 8.8 of [ITU-T G.9961]. + +### 10.7.1 MAP generation and distribution + +See clause 8.8.1 of [ITU-T G.9961]. + +### 10.7.2 MAP frame transmission + +See clause 8.8.2 of [ITU-T G.9961]. + +### 10.7.3 MAP header + +See clause 8.8.4 of [ITU-T G.9961]. + +### 10.7.4 TXOP descriptor + +Each TXOP is described by at least one TXOP descriptor. A TXOP descriptor is composed of a basic TXOP descriptor that may be extended by one or more additional TXOP descriptor extensions (see clauses 10.7.4.1.1 to 10.7.4.1.8). TXOP descriptor extensions supply additional information like scheduling information, timing information and TXOP attributes. + +Basic TXOP descriptors and TXOP descriptor extensions are each four octets in length. + +A TXOP descriptor represents the right of a certain node or a set of nodes to transmit within a certain TXOP. A CFTXOP shall be described using a single TXOP descriptor. A CBTXOP shall be described by either a single TXOP descriptor or by multiple TXOP descriptors (see clause 10.2.2.1). A STXOP shall be described using several TXOP descriptors representing the TSs within the STXOP. An FDSTXOP and an FDCFTXOP shall be described using a basic TXOP descriptor and an addition TXOP descriptor extensions. + +The domain master shall not assign more than 127 TXOP descriptors in the MAP, describing TSs, within a single STXOP (including CBTXOP). + +The differentiation between different TXOPs shall be done via the TXOP attributes extension, which shall be appended to the last TXOP descriptor of a TXOP. The TXOP attributes extension supplies the timing information for the TXOP (see clause 10.7.4.1). A node associated with a TXOP or a TS is uniquely identified in a TXOP descriptor by the *SID* field, which shall be set to the *DEVICE\_ID* of the node as was assigned by the domain master. + +A flow associated with a TXOP or a TS is uniquely identified in a TXOP descriptor by the combination (*SID*, *FLOW\_ID*). A *FLOW\_ID* is a unique identifier of a flow associated with the *SID*. + +A user priority associated with a TXOP or TS is uniquely identified in a TXOP descriptor by the tuple (*SID*, *PRI*). The *PRI* value shall represent the lowest MPDU priority that may be sent in the TXOP or TS. + +A special TXOP is specified for assignment to nodes for transmitting traffic associated with a bandwidth managed DLL multicast stream. These TXOPs are assigned to a DLL multicast stream by using the 'Multicast Indication' field in the basic TXOP descriptor, combined with the 'FLOW\_ID/PRI/MSID' field in the basic TXOP descriptor to identify the MSID of the stream and the 'SID' field in the basic TXOP descriptor to identify an intermediate node in the DLL multicast stream that is responsible for the transmission of data associated with the DLL multicast stream. The 'DID/Originating Node' field in the TXOP descriptor shall contain the originating node of the DLL multicast stream and together with the MSID field, uniquely identifies the DLL multicast stream in the domain. + +The differentiation between the full duplex TXOPs (FDSTXOP and FDCFTXOP) and the half duplex TXOPs shall be done via the 'FD TXOP Indicator' field in the basic TXOP descriptor. If the 'FD TXOP Indicator' field in the basic TXOP descriptor is set to '0', then it is a half duplex TXOP; otherwise, it is a full duplex TXOP. The differentiation between the FDSTXOP and the FDCFTXOP shall be done via the additional TXOP descriptor extensions (see clauses 10.7.4.1.6 and 10.7.4.1.7). + +Table 10-3 describes the basic TXOP descriptor. When the extension bit is set, the TXOP descriptor shall have an extension, as described in clause 10.7.4.1. Different types of TXOP descriptor extensions are distinguished by extension type. + +**Table 10-3 – Basic TXOP descriptor format** + +| Field | Octet | Bits | Description | +|-------------------------------|---------|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| SID | 0 | [7:0] | SID = 1-250 identifies the DEVICE_ID of the node assigned to the TXOP.
SID = 0, 255 indicates special values for the TXOP descriptor (see clause 10.7.4.2).
If this TXOP is an FDSTXOP, the SID is the DEVICE_ID of the central node. | +| DID/Originating Node | 1 | [7:0] | If Multicast Indication = 0:
  • DID = 0 indicates that the DID of the destination node of the flow is not known to the domain master.
  • DID > 0 indicates the destination node for the flow. DID shall be set to the DEVICE_ID.
If this TXOP is an FDSTXOP, the DID shall be set to 252.
If Multicast Indication = 1:
This field identifies the originating node of the DLL multicast stream for which this TXOP is assigned. | +| Multicast Indication/MAP type | 2 and 3 | [0] | If this field is a special TXOP descriptor of a MAP (see clause 10.7.4.2) it indicates the type of MAP that shall be transmitted:
0 indicates MAP-A, 1 indicates MAP-D.
If this field is not a special TXOP descriptor of a MAP this field contains the multicast indication:
1 indicates multicast/broadcast DID, 0 otherwise. | +| PR signal required | | [1] | This bit instructs nodes contending for transmission in a CBTS whether to use the PR signal:
0 – PR signal shall not be used.
1 – PR signal is required. | +| CBTS Closure Mode | | [3:2] | This field instructs nodes where to close a CBTS that was used for transmission (see in clause 10.2.2.1):
00 – Duration-based.
01 – Timeout-based from frame sequence start.
10 – Timeout-based from CBTS start.
11 – Reserved by ITU-T. | +| FD TXOP Indicator | | [4] | This field indicates whether this is a TXOP for half duplex transmission or a TXOP for full duplex transmission.
0 –CFTXOP or CBTXOP or STXOP.
1 –FDSTXOP or FDCFTXOP. | +| CBTXOP Indicator | | [5] | This field indicates whether this is a CBTXOP using the contention mechanism as described in clause 10.2.2.3.4 or using the contention mechanism as described in clause 10.2.2.3.8.
0 – using the contention mechanism as described in clause 10.2.2.3.4.
1 – using the contention mechanism as described in clause 10.2.2.3.8. | +| FlowID/PRI/MSID | | [13:6] | If Multicast Indication = 0: | + +**Table 10-3 – Basic TXOP descriptor format** + +| Field | Octet | Bits | Description | +|---------------|-------|------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| | | |
  • Identifies the flow or the user priority associated with the TXOP/TS.
  • Valid values for user priority assignments are 0-7
  • Valid values for FLOW_ID assignments are 8-250

If Multicast Indication = 1:

  • Valid values for MSID assignments are 1-250
  • Value 0 is reserved by ITU-T
  • Values 251- 254 are reserved by ITU-T
  • Value 255 indicates special values for the TXOP descriptor (see clause 10.7.4.2).

If this TXOP is an FDSTXOP or an FDCFTXOP, the FlowID/PRI corresponds to FlowID/PRI of the primary transmission.

If this TXOP is a CBTXOP with the CBTXOP indicator set to one, the FlowID/PRI shall set to zero.

| +| Last_in_Group | | [14] |

1 indicates the last TS of a group of TSs in STXOP, 0 otherwise.

Shall be set to zero for CFTXOP, CBTXOP using the contention mechanism as described in clause 10.2.2.3.8, FDCFTXOP and FDSTXOP.

| +| Extension | | [15] |

0 – No extension is present.

1 – This TXOP descriptor contains an extension.

| + +Several TSs within the same STXOP can be grouped together to specify common attributes for these TSs via a group information extension (see clause 10.7.4.1). Grouping of several TSs shall be done by setting the Last\_in\_Group indication in the TXOP descriptor of the last TS of the group. Groups are implicitly numbered according to their appearance in the MAP. The first group shall be identified as group number one and so on. If a group contains only one TS, the descriptor of this TS shall have its Last\_in\_Group bit set to one. + +#### 10.7.4.1 TXOP descriptor extension + +All TXOP descriptor extensions shall be of 4 octets and shall have the format described in Table 10-4. A TXOP descriptor may have more than one extension. + +**Table 10-4 – TXOP descriptor extension format** + +| Field | Octet | Bits | Description | +|----------------|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Extension data | 0 to 3 | [26:0] | Extension data (see clauses 10.7.4.1.1 to 10.7.4.1.8). | +| Extension Type | | [30:27] |

TXOP descriptor extension type:

  • 0 – TXOP attributes (see clause 10.7.4.1.2).
  • 1 – TXOP absolute timing (see clause 10.7.4.1.3).
  • 2 – Group information (see clause 10.7.4.1.4).
  • 3 – Maximum transmission limitation (see clause 10.7.4.1.5).
  • 4 – CBTS nodes information (see clause 10.7.4.1.6).
  • 5 – Additional TXOP attributes (see clause 10.7.4.1.7).
  • 6 – FD contention-free information (see clause 10.7.4.1.8).
| + +**Table 10-4 – TXOP descriptor extension format** + +| Field | Octet | Bits | Description | +|-----------|-------|------|-------------------------------------------------------------------------------------------| +| | | | 7 – FD contention group information (see clause 10.7.4.1.9).
8-15 – Reserved by ITU-T. | +| Extension | | [31] | 0 – No more extensions present.
1 – This TXOP descriptor contains more extensions. | + +##### 10.7.4.1.1 TXOP attributes extension data + +See clause 8.8.4.1.1 of [ITU-T G.9961]. + +##### 10.7.4.1.2 TXOP absolute timing extension data + +See clause 8.8.4.1.2 of [ITU-T G.9961]. + +##### 10.7.4.1.3 Group information extension data + +See clause 8.8.4.1.3 of [ITU-T G.9961]. + +##### 10.7.4.1.4 Maximum transmission limitation extension data + +See clause 8.8.4.1.4 of [ITU-T G.9961]. + +##### 10.7.4.1.5 CBTS nodes information extension data + +A CBTS nodes information extension shall be identified by extension type 4 and shall be used to specify the specific list of nodes that are allowed to contend in a particular CBTS as specified via a TXOP descriptor (see clause 10.7.4.1). The list of nodes shall be described by indicating the DEVICE\_IDs. Several CBTS nodes information extension may be used for a TXOP descriptor that describes a CBTS. + +In a CBTXOP using the contention mechanism described in clause 10.2.2.3.8, the specific list of nodes that are allowed to contend in each CBTS shall be the same, therefore only one CBTS nodes information extension shall be used for the CBTXOP descriptor. + +The CBTS nodes information extension is described in Table 10-5. + +**Table 10-5 – CBTS nodes information Extension Data format** + +| Field | Octet | Bits | Description | +|------------------------|-------|-------|----------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Include_Exclude | 0 | [0] | 0 – All nodes indicated in the following entries may contend in this CBTS
1 – All nodes indicated in the following entries shall not contend in this CBTS | +| Entry format | | [1] | 0 – byte map format
1 – bit map format | +| Reserved | | [7:2] | Reserved by ITU-T (Note) | +| Byte map format | | | | +| Entry number 1 | 1 | [7:0] | 0 = New nodes joining network
1 to 250 identifies the DEVICE_ID of a registered node
251 to 254 – Reserved by ITU-T
255 – This entry shall be ignored | +| Entry number 2 | 2 | [7:0] | 0 = New nodes joining network
1 to 250 identifies the DEVICE_ID of a registered node | + +**Table 10-5 – CBTS nodes information Extension Data format** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|---------------------------------------------------------------------------------------------------------------------------| +| | | | 251 to 254 – Reserved by ITU-T
255 – This entry shall be ignored | +| Reserved | 3 | [2:0] | Reserved by ITU-T (Note) | +| Extension Type and Extension | | [7:3] | See Table 8-64 | +| Bit map format | | | | +| Entry number 1 | 1 | [7:0] | 0 – New nodes joining network
1-250 identifies the DEVICE_ID of a registered node
251-255 – Reserved by ITU-T | +| Entry number 2 | 2 | [0] | Identifies status for DEVICE_ID= Entry number 1 +1
0 – Node included in the list
1 – Node not included in the list | +| Entry number 3 | | [1] | Identifies status for DEVICE_ID= Entry number 1 +2
0 – Node included in the list
1 – Node not included in the list | +| ... | | ... | ... | +| Entry number 8 | | [6] | Identifies status for DEVICE_ID= Entry number 1 + 7
0 – Node included in the list
1 – Node not included in the list | +| Entry number 9 | | [7] | Identifies status for DEVICE_ID= Entry number 1 + 8
0 – Node included in the list
1 – Node not included in the list | +| Reserved | 3 | [2:0] | Reserved by ITU-T (Note) | +| Extension Type and Extension | | [7:3] | See Table 8-64 | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +##### 10.7.4.1.6 Additional TXOP attributes extension data + +See clause 8.8.4.1.6 of [ITU-T G.9961]. + +##### 10.7.4.1.7 FD contention-free information extension data + +This clause is for further study. + +##### 10.7.4.1.8 FD contention group information extension data + +An FD contention group information extension shall be identified by extension type 8 and shall be used to specify the specific list of nodes that are allowed to contend in the FDSTXOP using the DQ contention access mechanism (see clause 10.2.2.5). The list of nodes shall be described by indicating the DEVICE\_IDs. Only nodes that are on this list shall be allowed to contend to be the secondary transmitter of the full duplex transmission and send MSG frames to the central node in this FDSTXOP. + +The FD contention group information extension is described in Table 10-6. + +**Table 10-6 – FD contention group information Extension Data format** + +| Field | Octet | Bits | Description | +|------------------------------|-------|-------|-------------------------------------------------------------------------------------| +| Entry Number | 0 | [7:0] | The total number that are allowed to contend in the FDSTXOP | +| Entry number 1 | 1 | [7:0] | The DEVICE_ID of the first node that is allowed to contend in the FDSTXOP | +| Entry number 2 | 2 | [7:0] | The DEVICE_ID of the second node that is allowed to contend in the FDSTXOP | +| ... | var | ... | ... | +| Entry number N | | [7:0] | The DEVICE_ID of the N th node that is allowed to contend in the FDSTXOP | +| Reserved | var | [2:0] | Reserved by ITU-T (Note) | +| Extension Type and Extension | | [7:3] | See Table 10-4 | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +#### 10.7.4.2 Special values for the TXOP descriptor + +See clause 8.8.4.2 of [ITU-T G.9961]. + +### 10.7.5 Auxiliary information field + +See clause 8.8.5 of [ITU-T G.9961]. + +### 10.7.6 MAP schedule persistence publication + +See clause 8.8.6 of [ITU-T G.9961]. + +## 10.8 Retransmission and acknowledgement protocol + +See clause 8.9 of [ITU-T G.9961]. + +## 10.9 Management and control message format + +See clause 8.10 of [ITU-T G.9961]. + +## 10.10 Channel estimation protocol + +See clause 8.11 of [ITU-T G.9961]. + +## 10.11 Connection management + +See clause 8.12 of [ITU-T G.9961]. + +## 10.12 Operation in the presence of neighbouring domains + +This clause is for further study. + +## 10.13 Inter-domain mobility support + +### 10.13.1 Inter-domain mobility through external control + +#### 10.13.1.1 Introduction + +In some network architectures, the mobility of an end point between different domain masters may be decided by an external controller. In this architecture, VLC nodes provide this external controller with all the information necessary to decide and perform the mobility of the VLC node from a domain to a different domain. + +![Diagram of Controller-based architecture for inter-mobility support. It shows a Controller connected to an external network (X) and two Agents. The Agents are connected to a Domain Master (DM) and a Candidate Domain Master (C-DM). The DM and C-DM are connected to End Points (EPs). The DM and C-DM have an overlapping area. The legend indicates: VLC link (red solid line), VLC control (red dashed line), Alien link (blue solid line), and Alien control (blue dashed line). The diagram is labeled G.9991(19)_F10-8.](29043c6ca27a7cfbc757a5d2eb029d33_img.jpg) + +``` + +graph TD + Controller[Controller] --- Switch[X] + Controller -.-> Agent1[Agent] + Controller -.-> Agent2[Agent] + Switch --- DM[DM] + Switch --- CDM[C-DM] + Agent1 <-.-> DM + Agent2 <-.-> CDM + DM --- EP1[EP] + DM --- EP2[EP] + CDM --- EP2 + CDM --- EP3[EP] + subgraph Overlap + EP2 + end + +``` + +The diagram illustrates a controller-based architecture for inter-mobility support. At the top, a **Controller** is connected via dashed blue lines (Alien control) to two **Agent** blocks and via a solid blue line (Alien link) to a network switch symbol (X). The switch is connected to a **DM** (Domain Master) and a **C-DM** (Candidate Domain Master) via solid blue lines. Each **Agent** has a bidirectional dashed red line (VLC control) to either the **DM** or **C-DM**. The **DM** and **C-DM** are connected to **EP** (End Point) blocks via solid red lines (VLC links). One **EP** is situated in an **Overlap** area between the dashed coverage boundaries of the **DM** and **C-DM**. The legend at the bottom defines: VLC link (solid red arrow), VLC control (dashed red double arrow), Alien link (solid blue arrow), and Alien control (dashed blue double arrow). The diagram is labeled G.9991(19)\_F10-8. + +Diagram of Controller-based architecture for inter-mobility support. It shows a Controller connected to an external network (X) and two Agents. The Agents are connected to a Domain Master (DM) and a Candidate Domain Master (C-DM). The DM and C-DM are connected to End Points (EPs). The DM and C-DM have an overlapping area. The legend indicates: VLC link (red solid line), VLC control (red dashed line), Alien link (blue solid line), and Alien control (blue dashed line). The diagram is labeled G.9991(19)\_F10-8. + +**Figure 10-8 – Controller-based architecture for inter-mobility support** + +The exchange of this information between the domain master and the controller may be done directly or through external agents. + +The definition of the external controllers and agents are out of scope of this Recommendation. + +The domain master of a domain that provides this inter-domain mobility shall provide to the external controller (or agents) the metrics for the following links (see clause 10.13.1.2): + +- link between the DM and each of the end points of its domain; +- link between the EPs in its domain and any other possible candidate DM that the end point may see. + +This information shall be made available through the LCMP protocol (see clause 10.23). + +#### 10.13.1.2 Metrics acquisition + +A DM shall measure the characteristics of the different links that are related to the inter-domain mobility support. + +![Diagram illustrating the metrics to be provided by the DM for each EP. The diagram shows a Controller connected to an X (switch), which is connected to two Agents. Each Agent is connected to a DM (Domain Manager). The DMs are connected to EPs (Edge Points). The DMs are also connected to the X via dashed blue lines. The DMs are connected to the EPs via red arrows labeled L-US_N ; L-DS_N. The DMs are also connected to the EPs via green arrows labeled C-US_N ; C-DS_N. The DMs are connected to the EPs via dashed lines. The DMs are connected to the EPs via a double-headed arrow labeled 'Overlap'. A legend at the bottom indicates that red arrows represent 'VLC link' and green arrows represent 'VLC candidate link'. The diagram is labeled G.9991(19)_F10-9.](d512ce4e3ac0de6c26d0e74a85ef2cbd_img.jpg) + +Diagram illustrating the metrics to be provided by the DM for each EP. The diagram shows a Controller connected to an X (switch), which is connected to two Agents. Each Agent is connected to a DM (Domain Manager). The DMs are connected to EPs (Edge Points). The DMs are also connected to the X via dashed blue lines. The DMs are connected to the EPs via red arrows labeled L-US\_N ; L-DS\_N. The DMs are also connected to the EPs via green arrows labeled C-US\_N ; C-DS\_N. The DMs are connected to the EPs via dashed lines. The DMs are connected to the EPs via a double-headed arrow labeled 'Overlap'. A legend at the bottom indicates that red arrows represent 'VLC link' and green arrows represent 'VLC candidate link'. The diagram is labeled G.9991(19)\_F10-9. + +**Figure 10-9 – Metrics to be provided by the DM for each EP** + +NOTE – In Figure 10-9 only one candidate DM is shown (DM2), however, several candidates and therefore several tuples C-US; C-DS may exist. + +- **L-USN**: *Estimation of the channel of the link between the EP that may need to roam and the DM*: In this case, it is a normal channel estimation within a domain, therefore, the DM may use any of the mechanisms described in this Recommendation for estimating the channel (see clause 10.10). +- **L-DSN**: *Estimation of the channel of the link between the DM and the DM that needs to roam*: In this case, it is a normal channel estimation within a domain. The DM can use any of the mechanisms described in the Recommendation for estimating the channel. However, it is likely that it will need a transmitter-triggered channel estimation (see clause 10.10). +- **C-USN**: *Estimation of the channel of the link between the EP that may need to roam and a new candidate DM*: In this case, the candidates DMs use the MAP-Ds sent in the IDCC channel by each of the EPs (on demand by the DM of their domain). The DM of the EPs in this transition zones should assign more MAP-D transmissions in the IDCC. +- **C-DSN**: *Estimation of the channel of the link between a candidate DM and an EP that needs to roam*: In this case, the EP may use the candidate DM MAP-D sent in the IDCC for channel estimation and report the measured information to its DM (see clause 10.4.5). + +#### 10.13.1.3 Fast transition of security mechanisms + +This clause is for further study. + +#### 10.13.1.4 Interface with alien controller + +The interface with alien controller shall be done through the L6 interface as defined in clause 10.23 and [ITU-T G.9962]. + +However, the data models to be used shall follow annexes A and B of this Recommendation for L1 and L6 interfaces, respectively. + +## **10.14 Dimming support and flicker avoidance** + +### **10.14.1 Dimming support** + +This Recommendation provides support for dimming technologies. However, this support varies depending on the PHY. + +When using a PHY based on [ITU-T G.9960] (see clause 8), the modulation does not guarantee a positive real modulated signal and therefore clipping may occur when using dimming techniques. However, this Recommendation specifies adaptive mechanisms that may be used to mitigate performance losses for deep levels of dimming. + +When using a PHY based on ACO-OFDM (see clause 9), the modulation used guarantees a positive real modulated signal that is added to the bias current in the LED. This way, during dimming no performance loss is coming from the modulation itself. + +### **10.14.2 Flicker avoidance** + +An ITU-T G.9991 system modulates the signal at very high frequency therefore no flicker is generated by the modulated signal itself. However, for low speed transitions between states (transmission state to non-transmission state), flicker shall be considered by the designer when implementing the scheduling if the average current injected into the medium is different for the two states. + +NOTE – ITU-T G.9991 systems should follow the guidelines provide in [b-IEEE 1789-2015] to avoid flicker. + +## **10.15 Inter-bandplan interoperability** + +See clause 8.18 of [ITU-T G.9961]. + +## **10.16 MIMO transmission** + +This clause is for further study. + +## **10.17 Operation with non-VLC uplink** + +For further study. + +## **10.18 DLL multicast stream** + +See clause 8.17 of [ITU-T G.9961]. + +## **10.19 Node information and capabilities exchange** + +See clause 8.19 of [ITU-T G.9961]. + +## **10.20 Metrics acquisition protocol** + +See clause 8.20 of [ITU-T G.9961]. + +## **10.21 Operation in power saving modes** + +See clause 8.21 of [ITU-T G.9961]. + +## **10.22 Layer 2 configuration and management protocol** + +See clause 8.22 of [ITU-T G.9961]. + +## **10.23 Payload compression in management messages** + +See clauses 8.24 and X.3 of [ITU-T G.9961]. + +## **10.24 PHY multicast binding protocol** + +See clause 8.16 of [ITU-T G.9961]. + +# **11 Security** + +See clause 9 of [ITU-T G.9961]. + +# **12 Management of ITU-T G.9991 nodes** + +## **12.1 Architecture and reference model** + +### **12.1.1 Architecture** + +A model of the ITU-T G.9991 management, control and security (MCS) architecture is depicted in Figure 12-1. The model consists of various entities located either within nodes, within a domain or external to the domain. MCS entities provide management, control and security of the layer they reside in as well as services and interfaces to enable MCS communications. + +The structure of MCS begins with the layers of the node; the physical (PHY) layer and the data link layer (DLL). Each of these has a specific MCS entity. Above these in the MCS hierarchy, but still within Layer 2, is the node management entity (NME), which is responsible for managing the node's overall functions. Outside of the node are two entities that reside in the same domain as the node. These are the security controller entity (SCE) and the domain master management entity (DMME). These manage and control their specific areas of responsibility (e.g., security for the SCE) within the domain. These two entities are still within Layer 2 as they are solely functioning to facilitate Layer 2 activities. These two entities are considered to operate at the domain level, unlike the node located ones that operate at the node or device level. The next entity is the global master entity (GME). This entity is defined as external to the domain, performing management and control functions for all domains within a specific home network. Global master (GM) functions are logical and able to be distributed among its managed domain masters (DMs). As GM functions concern actions that span multiple domains within a common network, it is referenced as operating at the network level for logical representation of its place in the MCS hierarchy. This is an arbitrary assignment given the logical nature of the GM. Entities that perform functions above the security controller (SC) and the GM or, in its absence the DM, are considered to be non-ITU-T G.9991 entities and out of scope. They are described in summary here as they may exist and effect the operation of the entities lower than them in the hierarchy. + +The SC and DM are depicted as separate entities as they might or might not be located within the same device and might or might not be associated with the same node. + +NOTE – The SC itself may be a proxy function versus a standalone entity, as it may be only a local presence of a remote authenticating system/entity that is out of scope of this Recommendation. The internal operation and structure of the SC is as well out of scope; only its operations facing into the domain are within scope of this Recommendation, such operations as represented by its messaging and functions as described in clauses 8 and 9. + +![Architecture of management, control and security diagram showing layers from Non-ITU-T G.9960 down to Node level, with various entities and logical links (L2, L3, L4, L5, L6, X).](32d36dfe7dc75b7c63f8edf0f28e4009_img.jpg) + +The diagram illustrates the architecture of management, control, and security across four layers: Non-ITU-T G.9960, Network level, Domain level, and Node. At the Non-ITU-T G.9960 layer, there are Remote authenticator entity and Remote management entity. The Network level contains Global master entity. The Domain level includes Security controller entity and Domain master management entity. The Node layer contains DLL, PHYs, DLL management entity, PHY management entity, and Node management entity. Logical links are labeled L2, L3, L4, L5, L6, and X. Notes 1 and 2 are present in the Network level. A Dimmer application entity is shown at the bottom right. A legend at the bottom defines the link types: Intra-node management links (solid line), Security links intra-domain (dotted line), Management and control intra-domain (dash-dot line), Management and control extra-domain (dashed line), and MCS links extra-domain (long dash-dot line). + +Architecture of management, control and security diagram showing layers from Non-ITU-T G.9960 down to Node level, with various entities and logical links (L2, L3, L4, L5, L6, X). + +NOTE 1 – In the absence of a GME or when the GM functions are distributed, the DMME may communicate directly with the remote management entity. + +NOTE 2 – The remote management entity may communicate with select nodes using specific read/write functions. + +**Figure 12-1 – Architecture of management, control and security** + +At the device level within the same domain, management and control messages are exchanged between node NMEs and between node NMEs and application entities (AEs). + +An AE may exchange management and control messages with the NME in its device or with another node's NME in the same domain (L1 interface) using the LCMP protocol (see clause 10.23). Nodes exchange management and control messages between NMEs to facilitate communications between nodes (L3 interface). These interactions are illustrated in Figure 12-2. + +Specific AE to AE communications are outside the scope of this Recommendation. + +![Figure 12-2: Device level management links diagram showing two devices, Device A and Device B, each containing a Node (Node A and Node B). Each node contains a Node management entity, a DLL management entity, and a PHY management entity. Application entities are shown above the nodes. Management links are labeled L1 (inter-device AE to/from far node), L2 (inter-device node to node), L3 (intra-device AE to/from far node), L4 (intra-device AE to/from far node), and L5 (intra-device AE to/from far node). Dimmer blocks are shown on the links between nodes.](c6212a3b14736d6a8c81ace75ae94ccf_img.jpg) + +Figure 12-2: Device level management links diagram showing two devices, Device A and Device B, each containing a Node (Node A and Node B). Each node contains a Node management entity, a DLL management entity, and a PHY management entity. Application entities are shown above the nodes. Management links are labeled L1 (inter-device AE to/from far node), L2 (inter-device node to node), L3 (intra-device AE to/from far node), L4 (intra-device AE to/from far node), and L5 (intra-device AE to/from far node). Dimmer blocks are shown on the links between nodes. + +G.9991(19)\_F12-2 + +Device level management links (logical) + +←·····→ Inter-device AE to/from far node + +←· · · ·→ Inter-device node to node + +← - - - -→ Intra-device AE to/from far node + +**Figure 12-2 – Device level management links** + +#### 12.1.1.1 Overall MCS structure + +See clause 6.1.1 of [ITU-T G.9962]. + +#### 12.1.1.2 Management and control entities + +See clause 6.1.2 of [ITU-T G.9962]. + +### 12.1.2 Reference model + +Figure 12-3 illustrates data-plane, control-plane and management-plane reference models for an ITU-T G.9991 transceiver. + +![Figure 12-3: ITU-T G.9991 reference model diagram. It shows three vertical reference models: Data-plane, Control-plane, and Management-plane. The Data-plane contains DLL and PHYs. The Control-plane contains a DLL management entity (DME) and a PHY management entity (PME). The Management-plane contains a Node management entity (NME). The Data-plane and Control-plane are separated by an A-interface, and the Control-plane and Management-plane are separated by an MDI.](c64555b7f91435b01997807dbb4bcc4c_img.jpg) + +Figure 12-3: ITU-T G.9991 reference model diagram. It shows three vertical reference models: Data-plane, Control-plane, and Management-plane. The Data-plane contains DLL and PHYs. The Control-plane contains a DLL management entity (DME) and a PHY management entity (PME). The Management-plane contains a Node management entity (NME). The Data-plane and Control-plane are separated by an A-interface, and the Control-plane and Management-plane are separated by an MDI. + +G.9991(19)\_F12-3 + +**Figure 12-3 – ITU-T G.9991 reference model** + +## 12.2 ITU-T G.9991 interface data model + +This clause is for further study. + +# **Annex A** + +## **LCMP communication through L1 interface** + +(This annex forms an integral part of this Recommendation.) + +## **A.1 LCMP\_CONTROL in L1 interface** + +LCMP frames conveying information via the L1 interface shall use 016 as LCMP\_CONTROL. + +## **A.2 Data model for L1 interface** + +For further study. + +# Annex B + +## LCMP communication through L6 interface + +(This annex forms an integral part of this Recommendation.) + +## B.1 LCMP\_CONTROL in L6 interface + +LCMP frames conveying information via the L6 interface shall use 516 as LCMP\_CONTROL. + +## B.2 Data model for L6 interface + +**Table B-1 – [ITU-T G.9961] L6 interface parameters** + +| Parameter | Param ID | Access type | Parameter value field | +|-----------|------------------|-------------|-----------------------| +| EPmetrics | 00 16 | R | See clause B.2.1 | + +### B.2.1 EP metrics + +**Table B-2 – Format of the EPMetrics parameter** + +| Field | Octet | Bits | Description | +|---------------------------|-------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Number of end points | 0 | [7:0] | Number of reported end point nodes (N). | +| EPIdentification[0] | 1 | [7:0] | Identification of the reported node.
It shall be formatted as described in Table B-3. | +| LocalLinkMetrics[0] | 2-5 | [31:0] | Reported performance metrics for the link between the reported end point and its DM. It shall be formatted as described in Table B-4. | +| CandidateLinkMetrics[0] | Var | Var | Reported performance metrics for the link between the reported end point and each of the candidate DMs. It shall be formatted as described in Table B-5. | +| ... | ... | ... | ... | +| EPIdentification[N-1] | Var | Var | Identification of the reported node.
It shall be formatted as described in Table B-3. | +| LinkMetrics[N-1] | Var | Var | Reported performance metrics for the link between the reported end point and its DM. It shall be formatted as described in Table B-4. | +| CandidateLinkMetrics[N-1] | Var | Var | Reported performance metrics for the link between the reported end point and each of the candidate DMs. It shall be formatted as described in Table B-5. | + +**Table B-3 – Format of EPIdentification field** + +| Field | Octet | Bits | Description | +|-----------|--------|--------|-------------------------| +| DEVICE_ID | 0 | [7:0] | DEVICE_ID of the node | +| MAC | 1 to 6 | [47:0] | MAC address of the node | + +**Table B-4 – Format of LinkMetrics fields** + +| Field | Octet | Bits | Description | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| BitsPerSecond | 0-3 | [31:0] | Bits [15:0] indicate the PHY data rate in bits per second from the reporting node to the detected node; Bits [31:16] indicate the PHY data rate from the detected node to the reporting node. (Note) | +| NOTE – Calculation shall follow the formula $\sum_{i=1}^N \text{BitsPerSecond}_i * \frac{T_i}{T_{Cycle}}$ where N is the number of channel estimation windows in the MAC cycle, BitsPerSecond i is the result of applying the same formula as Note 2 in Table 8-33 of [ITU-T G.9961] to the i -th channel estimation window, Ti is the duration of the i -th channel estimation window and TCycle is the duration of the MAC cycle. If no channel estimation is available for a particular window, RCM parameters shall be used for that window. If the data rate with the particular detected node is not available, the value of this parameter shall be set to FFFF 16 . | | | | + +**Table B-5 – Format of CandidateLinkMetrics fields** + +| Field | Octet | Bits | Description | +|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Number of candidate DMs | 0 | [7:0] | Number of candidates DMs reported by this node (M) | +| LinkIdentification[0] | 0-6 | [56:0] | Identification of the node with which the link is measured (detected node)
It shall be formatted as described in Table B-3 | +| BitsPerSecond[0] | 7-9 | [31:0] | Bits [15:0] indicate the PHY data rate in bits per second from the reporting node to the detected node; Bits [31:16] indicate the PHY data rate from the detected node to the reporting node. (Note) | +| ... | ... | ... | ... | +| LinkIdentification[M-1] | 0-6 | [56:0] | Identification of the node with which the link is measured (detected node)
It shall be formatted as described in Table B-3. | +| BitsPerSecond[M-1] | 7-9 | [31:0] | Bits [15:0] indicate the PHY data rate in bits per second from the reporting node to the detected node; Bits [31:16] indicate the PHY data rate from the detected node to the reporting node. (Note) | +| NOTE – Calculation shall follow the formula $\sum_{i=1}^N \text{BitsPerSecond}_i * \frac{T_i}{T_{Cycle}}$ where N is the number of channel estimation windows in the MAC cycle, BitsPerSecond i is the result of applying the same formula as Note 2 in Table 8-33 of [ITU-T G.9961] to the i -th channel estimation window, Ti is the duration of the i -th channel estimation window and TCycle is the duration of the MAC cycle. If no channel estimation is available for a particular window, RCM parameters shall be used for that window. If the data rate with the particular detected node is not available, the value of this parameter shall be set to FFFF 16 . | | | | + +# Annex C + +## ITU-T G.991 Capabilities + +(This annex forms an integral part of this Recommendation.) + +## C.1 ITU-T G.991 capabilities + +ITU-T G.991 specific capabilities shall be in the range A016 to AF16. + +**Table C.1 – List of ITU-TG.991-specific capabilities** + +| Capability type | Capability name | Capability length value | Capability value field | +|------------------------------------|--------------------|-------------------------|------------------------| +| A 016 | Wavelength support | Var | See Table C.1.1 | +| A 116 | Dimming support | 1 | See Table C.1.2 | +| A 216 | PHY support | 1 | See Table C.1.3 | +| A 316 | Spectrum support | 1 | See Table C.1.4 | +| A 416 -AF 16 | Reserved by ITU-T | | Reserved by ITU-T | + +NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +**Table C.1.1 – Wavelength support** + +| Field | Octet | Bits | Description | +|-------------------------------|-------|------|-----------------------------------------------------------------------------------------------------------| +| Transmission peak wavelengths | Var | Var | List of individual peak wavelengths attached to this device for transmission (Note)
See Table C.1.1.1. | +| Reception peak wavelengths | Var | Var | List of individual peak wavelengths attached to this device for reception (Note)
See Table C.1.1.1. | + +NOTE – See [b-IEC 62504:2014] for the definition of peak wavelength. + +**Table C.1.1.1 – Peak wavelength list** + +| Field | Octet | Bits | Description | +|----------------------------|---------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Number of peak wavelengths | 0 | [7:0] | Number of devices with individual peak wavelengths attached to this device (N) coded as an unsigned integer from 1 to 254.
Values 0 and 255 are reserved by ITU-T. | +| PeakWI[0] | 1 and 2 | [11:0] | First peak wavelength attached to this node (Note 2) coded as an unsigned integer representing nanometres. | +| Reserved | | [15:12] | Reserved by ITU-T (Note 1). | +| ... | ... | ... | ... | +| PeakWI[N-1] | Var | [11:0] | Last peak wavelength attached to this node (Note 2) coded as an unsigned integer representing nanometres. | +| Reserved | | [15:12] | Reserved by ITU-T (Note 1). | + +NOTE 1 – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. + +NOTE 2 – Peak wavelength is in the range of 200 nm to 1200 nm. + +**Table C.1.2 – Dimming support** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|---------------------------------------------------------------------------------------------------------------------------------------| +| ExtendedDimmingSupport | 0 | [0] | If set to one, the node supports the improved supported dimming range mechanism described in clause 8.1.4.4.7; set to zero otherwise. | +| Reserved | 0 | [7:1] | Reserved by ITU-T (Note). | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +**Table C.1.3 – PHY support** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| PHYSupport | 0 | [3:0] | Bitmap indicating the support of the PHY layers described in this Recommendation. If set to one, indicates support for that particular PHY layer.
Bit 0 (LSB): G.9961-based OFDM
Bit 1: ACO-OFDM
Bit 2: Reserved by ITU-T
Bit 3: Reserved by ITU-T | +| Reserved | 0 | [7:4] | Reserved by ITU-T (Note) | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +**Table C.1.4 – Spectrum support** + +| Field | Octet | Bits | Description | +|-------------------------------------------------------------------------------------------------------------|-------|-------|--------------------------------------------------------------------------------------| +| PMSCUsed | 0 | [0] | If set to one, this node allows the use of the subcarriers 0 to 10 for transmission. | +| Reserved | 0 | [7:1] | Reserved by ITU-T (Note). | +| NOTE – Bits that are reserved by ITU-T shall be set to zero by the transmitter and ignored by the receiver. | | | | + +## C.2 Excluded ITU-T G.9961 capabilities + +The ITU-T G.9961 capabilities (see Table 8-16.5 of [ITU-T G.9961]) listed in Table C.2 shall not be used in an ITU-T G.9991 network. + +**Table C.2 – List of ITU-T G.9961 capabilities not applicable to ITU-T G.9991** + +| Capability type | Capability name | +|------------------|--------------------------------| +| 05 16 | Run-Length Compression Support | + +# Appendix I + +## Introducing a DC offset when using a PHY layer based on Recommendation ITU-T G.9960 + +(This appendix does not form an integral part of this Recommendation.) + +Figures I.1 and I.2 show an example on how to introduce a DC component to the modulated signal in order to connect an ITU-T G.9991 system using a PHY layer based on [ITU-T G.9960] (see clause 8) to the optical transceivers. + +![Block diagram for the transmit side (Figure I.1)](18d7d8de298d79e7bc87af5217f11203_img.jpg) + +The diagram shows a transmit side circuit. On the right, a block labeled 'G.hn AFE' contains two output ports, 'TX\_P' and 'TX\_N'. Each output is connected through a series of a resistor and a capacitor to an LED. The two LEDs are connected in series between a VCC supply and ground. The VCC supply is connected to the top LED through a resistor, and the bottom LED is connected to ground through a resistor. The label 'G.9991(19)\_FI.1' is at the bottom right. + +Block diagram for the transmit side (Figure I.1) + +Figure I.1 – Block diagram for the transmit side + +![Block diagram for the receiver side (Figure I.2)](86bd357c573c9696393f5bde4d4cce4f_img.jpg) + +The diagram shows a receive side circuit. On the left, a block labeled 'G.9960-based AFE' contains two input ports, 'RX\_P' and 'RX\_N'. Each input is connected through a series of a capacitor and a resistor to a 'Transimpedance amplifier' block, which is represented by a triangle symbol. The output of the amplifier is connected to a photodetector (PD) through a series of a capacitor and a resistor. The PD is connected between a VCC supply and ground. The VCC supply is connected to the PD through a resistor, and the PD is connected to ground through a resistor. The label 'G.9991(19)\_FI.2' is at the bottom right. + +Block diagram for the receiver side (Figure I.2) + +Figure I.2 – Block diagram for the receiver side + +# Bibliography + +- [b-IEEE 1789] IEEE 1789-2015, *IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers.* +- [b-IEC 62504] IEC 62504-2014, *General lighting – Light emitting diode (LED) products and related equipment – Terms and definitions.* + + + +## SERIES OF ITU-T RECOMMENDATIONS + +| | | +|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------| +| Series A | Organization of the work of ITU-T | +| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues | +| Series E | Overall network operation, telephone service, service operation and human factors | +| Series F | Non-telephone telecommunication services | +| Series G | Transmission systems and media, digital systems and networks | +| Series H | Audiovisual and multimedia systems | +| Series I | Integrated services digital network | +| Series J | Cable networks and transmission of television, sound programme and other multimedia signals | +| Series K | Protection against interference | +| Series L | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant | +| Series M | Telecommunication management, including TMN and network maintenance | +| Series N | Maintenance: international sound programme and television transmission circuits | +| Series O | Specifications of measuring equipment | +| Series P | Telephone transmission quality, telephone installations, local line networks | +| Series Q | Switching and signalling, and associated measurements and tests | +| Series R | Telegraph transmission | +| Series S | Telegraph services terminal equipment | +| Series T | Terminals for telematic services | +| Series U | Telegraph switching | +| Series V | Data communication over the telephone network | +| Series X | Data networks, open system communications and security | +| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities | +| Series Z | Languages and general software aspects for telecommunication systems | \ No newline at end of file